text:
Tap water clean enough to treat wounds
Medical workers in disaster areas no longer have to wait for sterile equipment before they clean and dress wounds, thanks to Australian research.
Professor Rhonda Griffiths, of the University of Western Sydney's Centre for Applied Nursing, says as long as water is good enough to drink, evidence suggests it will be good enough to clean uninfected wounds.
"We've demonstrated that some of the traditional ways of doing dressings are unnecessarily expensive and labour intensive," says Griffiths.
She adds that if there is any doubt that the tap water is suitable for drinking, it can be boiled before use.
Griffiths and colleagues recently completed a systematic review of evidence for the Cochrane Collaboration comparing the use of saline versus tap water to clean uninfected wounds.
The review found that washing wounds, including leg ulcers, with water did not show an increase in infection or decrease in healing time, compared to using saline, she says.
As a result, the Cochrane Collaboration is now recommending tap water is used to clean wounds in developing countries and disaster zones, says Griffiths.
In the community
Community nurses, who treat people at home, first triggered the investigation into the use of tap water to clean wounds, says Griffiths.
While hospitals routinely use saline or sterilised water to clean uninfected wounds, community nurses have traditionally relied on people to simply shower before they dress their wounds.
"So in hospitals you had one practice," says Griffiths. "And the community had another."
Both practices were based on tradition rather than evidence, she says.
One of the studies included in Griffiths' Cochrane review was carried out by her team.
It was a six-week double blind, randomised controlled trial in southwestern Sydney that studied the healing and infection rate in 49 wounds of 35 patients washed with saline, compared with equivalent patients who were washed with tap water.
"We found that there was no difference," she says.
"That tells us that if you have got clean tap water that you can drink, it is perfectly safe to wash wounds with that tap water if those wounds aren't infected."
Griffith says the research is changing the way we think about managing some types of wounds.
"It's the cleanliness rather than the sterility [that's important]," she says.
Better for patients and cheaper
Griffiths says washing wounds with tap water would save money in hospitals, especially the cost of the disposable sterile equipment that is required when using saline.
Patients also prefer washing with water, she says, because they can get out of bed and take a shower.
While tap water may be safe and effective, Griffiths still wants to confirm the findings and find out if saline offers any advantages by carrying out a much larger randomised controlled trial.
She has applied for funding from the National Health and Medical Research Council to carry out a trial involving 400 wounds.

source: HuggingFaceFW/fineweb-edu


text:
SPLITTING TERRACED HOUSES INTO SINGLE UNITS USING OBLIQUE AERIAL IMAGERY
- Institute of Optical Sensor Systems, DLR Berlin, Germany
Keywords: Façade Splitting, Oblique True Ortho, Building Segmentation
Abstract. This paper introduces a method to subdivide complex building structures like terraced houses into single house units comparable to units available in a cadastral map. 3D line segments are detected with sub-pixel accuracy in traditional vertical true orthomosaics as well as in innovative oblique true orthomosaics and their respective surface models. Hereby high gradient strengths on roofs as well as fac¸ades are taken into account. By investigating the coplanarity and frequencies within a set of 3D line segments, individual cut lines for a building complex are found. The resulting regions ideally describe single houses and thus the object complexity is reduced for subsequent topological, semantical or geometrical considerations. For the chosen study area with 70 buidling outlines a hit rate of 80% for cut lines is achieved.

source: openbmb/Ultra-FineWeb


How Spicy Beef Tripe Soup Became a Mexican-American Breakfast Staple
This story is over 5 years old.
How Spicy Beef Tripe Soup Became a Mexican-American Breakfast Staple
Picky Mexican-American Millennials call menudo a comfort breakfast food, especially after a night of drinking. And the reason why may lie in its working-class roots.
September 2, 2015, 8:22pm
Does a pot of boiling tripe that smells like manure sound like your kind of hangover cure? If you grew up on menudo—the Mexican breakfast soup notoriously made with odorous chunks of stomach lining, hominy, and spices—it's the next best thing to some hair of the dog.
Menudo is the essential weekend breakfast for many Mexican-Americans in California, Texas, Arizona, and New Mexico of any generation; specifically, it's the go-to dish after a night of drinking.
But how exactly does a soup made of differently textured stomach lining stay at the top of the breakfast list for Millennial Mexican-Americans, who most likely grew up on Pop-Tarts, school pizza, and fast food?
READ: The Offal Osteria Is Putting the Guts Back into Florence's Former Red Light District
"Menudo is a working-class sopa," says Enrique Ochoa, Professor of History and Latin American Studies at Cal State LA, respected historian, and published author on Latin American issues.
Ochoa notes that menudo did not become popular until around the 1930s and 1940s, when migrant workers settled in urban hubs like San Antonio and East Los Angeles looking for work and establishing communities. At the time, Sinaloans and Michoacans—people from different Mexican states who would otherwise never speak to each other back home—became neighbors. Thus, they started to swap recipes.
Spoonful of stomach
Think of menudo as one of the first Mexican fusion foods on the West Coast.
In American culture, surrogate tías (aunts) soon came into play, making menudo as American as eggs and bacon for their families. The stereotypical Mexican señora image depicted on the labels of Juanita's canned menudo reminded many of their own moms or half-dozen aunties. This convenient Americanization of tripe soup beget the common Mexican family ritual of eating menudo on Sunday mornings, as well as the BYO pot system at establishments that serve menudo. Commercialization glossed over the details of what exactly menudo was, instead focusing on the vibrant colors and spicy flavors, propelling the red, palate-friendly broth of menudo into the mainstream.
Most people who grew up eating menudo can tell you that their own grandmother or abuelita has the tendency to add a lot of dried red chilies. But other regions of Mexico don't serve that same firewater-style soup. Sinaloans prefer a clear broth with hominy and no chile at all. People from DF like pancita, which is menudo under a different name, with no hominy filler but still crimson in color. Some cooks add cabeza (cow head) and pata (pork feet). These cuts of meat require hours to break down into gelatin, thus creating a savory, thick broth. The smell of it cooking is potent, like a cartoon aroma that can slap someone around if they're not careful.
Jesus Raya, the menudo cook in a Mexican restaurant in Los Angeles
Menudo is also the official food of any celebration in a Mexican-American household that takes place in the morning or early afternoon. Baby shower? The mom-to-be better be craving beef stomach. Funeral? No one is ever too sad to eat some tripe.
During the research phase of this article, I wanted to dive into the ethnological view of menudo, so I contacted Chicano Latino Research Center director Catherine Sue Ramírez at UC Santa Cruz. Instead, she referred me to her mother.
"I don't like stinky meat," Edna Ramirez tells me before sharing her recipe over the phone.
Ramirez, an LA Times Best Home Cook awardee, cautions me to thoroughly wash all the meat used in menudo with lemon juice. Tripe—both the bristled and the honeycomb cuts—can give off sulfuric smells that only a grandma can love. Those same compounds can also contaminate the broth and make it literally taste like the food that it was digesting a few weeks ago.
Oregano, crushed dried red chilies, and chopped onion are the traditional toppings for menudo.
I think of menudo as the persistent family member who keeps in touch no matter how far you may go in life. To give but one example, I recently proposed to my girlfriend and we moved to northern California, some 600 miles away from Los Angeles (and my favorite Mexican bakery). Soon after the proposal, my future mother-in-law made the trek up from LA just to celebrate.
You can probably guess what we celebrated with.
That awful boiling stomach stew odor found me like some sort of fugitive, dragging me kicking and screaming to the kitchen table. It has been here longer than I have and will continue long after I'm gone. And I have a feeling that I am not the only one that feels this way. Love it or hate it, menudo is here to stay.


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A circle hook is a type of fish hook which is sharply curved back in a circular shape. It has become widely used among anglers in recent years because the hook generally catches more fish and is rarely swallowed. Since the circle hook catches the fish on the lips at the corner of its mouth, it usually decreases the mortality rates of released fish as compared to J-hook (like O'Shaughnessy or Octopus hooks) which are often swallowed by the fish, causing damage to the gills or vital organs.
The circle hook's unique shape allows it to only hook onto an exposed surface, which in the case of a fish means the corner of its mouth. The fish takes the baited hook and swallows it, and as the hook is reeled in, it is safely pulled out of the fish until it reaches the mouth. At this point it will catch the corner of the mouth of the fish, resulting in fewer gut-hooked fish.
In terms of technique, it is important to not strike (or set the hook) when the fish bites, but rather just reel in. The act of striking while using a circle hook often results in the hook being pulled out of the fish altogether.
Studies have shown that circle hooks do much less damage to billfish than the traditional J-hooks, yet they are at just as effective for catching billfish. This is good for conservation, since it improves survival rates after release.


Ventriculi cerebrali mariti fathers day 2016
Definition of ventriculi in the the-test.de dictionary. Meaning of ventriculi. What does ventriculi mean? Information and translations of ventriculi in the most comprehensive dictionary definitions resource on . Define ventriculi. ventriculi synonyms, ventriculi pronunciation, ventriculi translation, English dictionary definition of ventriculi. n. pl. ven·tric·u·li A hollow digestive organ, especially the stomach of certain insects or the gizzard of a bird. Jan. 28, Ventricular arrhythmia is a rare occurrence in the pediatric population and is often an unexpected finding in patients with otherwise normal hearts. However, when a child does present with ventricular arrhythmia, specific causes warrant consideration and guide the subsequent work-up and treatment strategy.
Ventriculi cerebrali mariti fathers day 2016
If you are looking ventriculus]: FilterCopy - Things Fathers Do (Father's Day Special) - Ft. Rajat Kapoor, Rohan Shah and Madhu Gudi
Ventricular arrhythmia is a rare occurrence in the pediatric population and is often an unexpected finding in dayy with otherwise normal hearts. Xerox workcentre 3119 paperport, when a child does present venntriculi ventricular lyric walls vybe firefox, specific causes warrant consideration and guide the subsequent work-up and treatment strategy. Patients with known heart disease for example, congenital heart disease, cardiomyopathy or channelopathies may be at risk of ventricular arrhythmia and require a different mriti compared with patients who have normal hearts. Ventricular arrhythmia in a normal ventriculi cerebrali mariti fathers day 2016 can range from infrequent ectopy to incessant ventricular tachycardia VT. Premature ventricular complexes PVCs are a common finding in pediatric patients of all ages and may be seen on a Holter monitor in about 40 percent of otherwise healthy children. When PVCs are rare, isolated and monomorphic, they usually do not require extensive evaluation in an otherwise healthy child and have an excellent prognosis. Spontaneous resolution over time is quite possible and is more likely the centriculi the patient is at the time of presentation. However, when the PVC burden is more frequent or more complex that is, multiform PVCs, couplets or nonsustained VTit necessitates further work-up and possibly longitudinal follow-up.
Oct 10, · Atlas de neuroanatomie - Ventriculi cerebrali 1. VENTRICOLII CEREBRALI VENTRICOL LATERAL VENTRICOLUL III APEDUCTUL LUI SYLVIUS VENTRICOL IV Corn frontal Corn occipital Raspantie ventriculara Corn temporal Gaura lui Monro Gaura lui Luschka (12) Canal ependimar 2. Recently, Fr. Wade Menezes did a "Live" Radio Interview with Mater Dei Radio out of Portland, OR. Dina Marie Hale, Program Director, interviewed Fr. Wade during her show "In Person with Dina Marie." In this podcast, they talk about three things: The Closing of the Jubilee Year of Mercy, Advent, and the Immaculate Conception. Definition of ventriculi in the the-test.de dictionary. Meaning of ventriculi. What does ventriculi mean? Information and translations of ventriculi in the most comprehensive dictionary definitions resource on . Synonyms for os ventriculi in Free Thesaurus. Antonyms for os ventriculi. 5 synonyms for os: atomic number 76, osmium, operating system, oculus sinister, bone. What are synonyms for os ventriculi? On World Food Day, Oct. 16, , a team of three St. Joseph High School students won first place in the Super Chef Competition, which was one of the activities that took place during the World Food Day events at the St. Croix campus of the University of the Virgin Islands. The three students on the team were Xiaxiang Washington, Kezia Williams and. Define os ventriculi. os ventriculi synonyms, os ventriculi pronunciation, os ventriculi translation, English dictionary definition of os ventriculi. The symbol for osmium. abbr. 1. or O/S Old Style 2. operating system 3. ordinary seaman n. pl. o·ra A mouth or an opening. Cancer of the stomach (Cancer Ventriculi) Definition and causes Cancer of the stomach was previously a very frequent form of cancer, but in the last 40 years, the number of new cases, with no known cause, dropped to third. Now diagnosed around. new cases per. years, and slightly more die from the disease each year. Week 1 Term 3 Dear Parents, Students, Staff and Friends of the Magdalene Community, Magdalene Feast Day was celebrated today which saw our community come together to celebrate a special Mass for the feast day of Mary Magdalene followed by a school fair which raised money for the Care Fund that supports families within the school. Cost: $20 for the day BIO: David Vincent Meconi, S.J., the-test.de (Oxon.) is Associate Professor of Historical Theology, as well as the Director of the Edmund Campion Center for Catholic Studies at Saint Louis University; he is also the editor of Homiletic and Pastoral Review. Cavitate a encefalului, umplută cu lichid cefalorahidian. Acestea sunt numerotate de la 1 la 4, dar primul şi al doilea sunt denumite mai curând.Kropj, Ovulation, Vlcm ventriculi, LungenphthiM, Wurmfortsatz- entzundung, GaMeriblasenentzundung . Labor, maritime, Luc-sur-Mer. e dei vertebrati (n «m cranici, meseneefalo, rombeneefalo, circonwlmioni cerebrali, morfol. Curtois, Father, Keeper, Mus. .. JMtan. o Day, Cameron Donald (), Prof., and Dir. Jhon Day, Bulwarke of Defence againste all Sicknes, Sornes, and Woundes, that dooe daily Collinson (Peter), Memoirs: Lettsom ; Father gilVs Works. *De Ventriculi et intestinorum ratione in morbis. A Maritime State considered, as to the health of Seamen. De Tuberculosi Cerebrali commentatio. [A criticism ou Kramer's Aural Surgery of the present day.] 8vo. I Seni e le Vene Cerebrali in relazioue alle varie forme delle Alienazioni .. *De Polypis Ventriculi et de setiologia Polyporura. De I'influeuce de I'age relatif des Parents sur le sexe des enfants. A Maritime State considered, as to the health of Seamen. Infarctus vasorum ventriculi.. Wounds and Fistula of the . Implications of Sight — Double Vision, Half Visions, Apparitions, Day and Night Vi- sion, &c. .. Feyjoo (The Father) Considerations on the use and abuse of physic. Tr. Span. —31 99 History of the Maritime Wars of the Turks. Translated. Digitized by the Internet Archive in https://arch i ve. o rg/detai Is/b2 1 L' ag- glutinabilitS du bacillog^ne du tcJtanos, dernier vestige de sa parents .. Tids we 11 (H.H) Amildcaseof tetanus; recovery in four days. Le iniezioni cerebrali nel te- tano. Coldevin (O. A.) To tilfaelde af tetani ved dilatatio ventriculi. '^De Polypis Ventriculi et de ^Etiologia Polv- porum. Jiion Day, Bulwarke of Defence againste all Sicknes, Sornes, and Wou rides, A Maritime State considered, as to the health of Seamen. De Tuberculosi Cerebrali commentatio. Liverpool, Advice to Parents on the management of children in Inocu-. Antoni (L. J.) Actio Ventriculi in comminuendis cibis. Davy (Sir Humphry) Salmonia, or days of Fly-fishing, in a series of History of the Maritime Wars of the Turks. Sangermano (Father) The Burmese Empire. cepbalica nervi sympathici ejusque conjunctionibus cum nervis cerebrali- bus. monthly the-test.de peru monthly the-test.de monthly .. monthly the-test.de monthly. - Use ventriculi cerebrali mariti fathers day 2016 and enjoy
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Slow movement resistance training increases muscle thickness and strengthPosted on Tuesday, 8 January, 2013 by anthony
Recent research has provided further evidence for the support of slow movement repetitions for muscle building. In this study older men and women performed low intensity (50% of 1 rep max) resistance exercises (leg extensions and flexion) to working the quadriceps and hamstring muscle groups. One group completed the repetitions at a normal speed (1-second concentric phase [lifting phase], 1-second eccentric phase [lowering phase] and 1-second rest between each repetition) whilst the experimental group completed the repetitions at a much slower speed (3-second concentric phase, 3-second eccentric phase, and 1-second isometric with no rest between the repetitions).
The effect of slow movement resistance training on muscle size and strength
The researchers found that whilst both groups increased strength it was only the slow repetition group that showed significant increases in thigh muscle thickness. Therefore, for older individuals the combination of low intensity resistance exercise (i.e. 50% of 1RM) with slow movement speed (3-second concentric and eccentric with 1-second isometrics) appears to effective for muscle building.
Watanabe Y, Tanimoto M, Ohgane A, Sanada K, Miyachi M, Ishii N. (2013) Increased muscle size and strength from slow-movement, low-intensity resistance exercise and tonic force generation. J Aging Phys Act. 2013 Jan;21(1):71-84.Back to Muscle Building News


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Ghimbav Masterplan
Following the analysis of the main urban indicators, our team diagnosed the Brasov metropolitan area and Ghimbav's position, with strong points, weaknesses, opportunities and vulnerabilities. The following steps were: creating a sustainable city development strategy with a focus on priorities, formulating a vision and a concept for city development appropriate to the conclusions of the previous stages.
The concept for the spatial development was designed in relation to the main attractors and their evolution in time: intensifying economic and social exchanges with Codlea and Brașov, while connecting the airport and the innovation hub with the existing city.
The objectives when designing the urban planning concept were: Mobility and accessibility at a metropolitan level, increasing life quality, a balanced development of production and services, a connected, open and participative administrative system, sustainability for the pilot-projects, therefore for the whole development.
The last step of the strategy is the description of a series of pilot projects for the city in order to facilitate and strengthen the development in the direction of the stated vision.
Client: Municipality of Ghimbav
Year, location: 2017, Ghimbav, Ro
Type, program: International urban planning competition
Outcome: 3rd Prize
Size: XXL / 2500 ha
Team: Wolfhouse Productions + urb. Cristina Pavelescu
Second Prize – Competition for the Spatial Development in Ghimbav


How long do beef sausages take to cook?
How do you cook beef sausages?
Just bring a saucepan of water to the boil, and then place the uncooked sausages in the water. Make sure they're completely submerged in the water, and reduce the heat to a gentle simmer. Let the sausages simmer for about 10 minutes, then remove them from the water and dry them off with a paper towel.
How do you tell if beef sausages are cooked?
To determine whether it's done, you can measure the internal temperature with a meat thermometer. Sausages should reach 155–165°F (68–74°C). Alternatively, boiling them before cooking in a pan or on a grill can ensure that they're thoroughly cooked and remain moist.
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How do you cook beef sausage on the stove?
 1. PAN FRY. Cut Smoked Sausage sections in half lengthwise or into 1'2″ slices. Add to non-stick skillet over medium heat. Cook 6-9 minutes, turning frequently.
 2. STOVE TOP. Add sausage to 2-3 inches of boiling water.
 3. GRILL. Grill over medium-high heat for 12-14 minutes, turning frequently.
How long do sausages take to cook?
What is the best way to cook sausages?
Pan-frying is probably the most popular way to cook sausage. What makes it so effective is the fact that you can fry other ingredients alongside the sausage, which will acquire their flavors during cooking. Set your stove to medium heat and heat your pan or skillet for a couple of minutes, until it gets hot.
How do you tell if a sausage is cooked?
Use a meat thermometer. Insert the needle tip into the end of the sausage and measure the internal temperature of the meat. When the internal temperature has reached 160°F (70°C) for pork and beef or 165°F (74°C) for chicken and turkey for at least 30 seconds, the sausage is fully cooked and ready to serve.
Is a little pink in sausage OK?
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How do you know when sausages are cooked in a frying pan?
Fried sausages recipe
Should you boil sausages before frying them?
When you cook raw or fresh sausage, pre-boiling can bring the meat to a safe internal temperature faster, which helps eliminate any foodborne pathogens in the meat. However, while you can boil sausage before frying, it is usually not necessary.
How do you cook sausage in a frying pan?
 1. Spray a skillet with cooking spray.
 2. Add sausage.
 3. Cook over medium-high heat until browned, about 5 minutes, turning links often.
 4. Reduce heat to medium-low.
 5. Carefully add ½ cup water to skillet.
Can you bake sausages instead of frying?
There are many ways to cook sausages, but cooking them in the oven is often the simplest method. You don't have to stand over them, turning them in a frying pan or on the grill. And cooking them on foil means easy clean-up. … Then, depending on their size, bake them for 20 to 40 minutes in the oven at 350 °F (177 °C).
Should you pierce sausages?
Never, ever prick a sausage. … Cook sausages slowly over low heat on a greased grill, turning several times. High heat will simply cause them to split their skins and expunge their precious bodily fluids. Sausages also like a little rest after cooking.
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Is it better to fry or bake sausages?
Don't bake your sausages
While this seems like the healthy option, it doesn't provide the fry-up experience that pan cooking does. Baking prevents the exterior from developing that lovely umami taste we all crave.
Is it safe to eat undercooked sausage?
Yes, you can get severely sick by eating undercooked sausage, but then again it depends on what type of sausage you're eating. … They're not magicians or psychics and they can't see if the sausage contains a harmful bacteria such as Trichinosis.
How long does it take to cook sausage at 350?
I'm cooking


text:
A friction hinge is also referred to as a torque hinge, friction clutch or friction engine. A friction hinge is usually used to hold a pivoting member in a set position until acted upon by another force which exceeds its' rated torque rating. Common applications are all around us in our everyday lives, but they are embedded in a host system to hide them. We design them for use in notebook computers, lcd applications, cell phones,medical devices, aerospace systems, computer racks, advertising components, recreational vehicles, cabinet doors, gate systems and automotive components like armrests and visors. What differentiates friction hinges is the mechanical means in which the friction is engineered to hold the pivoting member in place. Most applications create frictional hold by having interference between 2 components which exert a force on each other to impede movement. The amount of torque produced is a function of the interference among other variables such as material, lubrication, contact area and temperature of the environment it is used. Of course different applications require different materials for their construction. Extreme high temperatures might require a steel or carbon impregnated friction element. A hinge for a laptop might need high cycle life of 50,000+ without loosing appreciable torque. Clean room applications need a hinge which must not particulate past a certain criteria. Some hinges must not conduct electricity, have any backlash or produce any noise over their useful life. At Mechanical Motion Technologies we can design for your specific application and specifications. Contact us to discuss your application at _URL_
What is a friction hinge?
By Mechanical Motion Tech LLC|2019-11-08T13:52:13+00:00October 9th, 2013|damping, manufacturing, mechanical engineering, patents, rotary viscous damping, Uncategorized|
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source: m-a-p/FineFineWeb


Take the 2-minute tour ×
Let M = (Q,∑, q0,A, δ) be an FA. Below are other conceivable methods of defining the extended transition function δ∗. In each case, determine whether it is in fact a valid definition of a function on the set Q × ∑∗, and why. If it is, show using mathematical induction
a. For every q ∈ Q, δ ∗ (q,) = q; for every y ∈ ∗, σ ∈, and q ∈ Q, δ ∗ (q, yσ ) = δ ∗ (δ ∗ (q, y), σ ).
b. For every q ∈ Q, δ ∗ (q,) = q; for every y ∈ ∗, σ ∈, and q ∈ Q, δ ∗ (q, σy) = δ ∗ (δ(q, σ ), y).
c. For every q ∈ Q, δ ∗ (q,) = q; for every q ∈ Q and every σ ∈, δ ∗ (q, σ ) = δ(q, σ); for every q ∈ Q, and every x and y in ∗, δ ∗ (q, xy) = δ ∗ (δ ∗ (q, x), y).
I stark at the first(a), if i need to proof in induction what is the initial step
and n step to n+1 step? can you show me the proof?
share|improve this question
This is extremely hard to read. I started to format it for you but got hung up on (a). I guessed what you meant by $\delta^*(q,\ )=q$, but I was lost at the next part: $y\in *,\sigma\in$. At that point I simply gave up. Could you attempt to reformat it or at least explain what your notation means? – Rick Decker Oct 11 '12 at 1:19
1 Answer 1
You should probably edit your question with the work you've done.
First, your question seems ill-specified because you claim that $\delta^*$ is a function on $Q \times \Sigma^*$ but I really think you mean it's a function from $Q \times \Sigma^*$ to $Q$.
Next you need to consider what you might do induction on. You want to show that this function correctly produces some $q \in Q$ given any input $(q, w)$ with $q \in Q$ and $w \in \Sigma^*$. This may or may not be intuitive but since the definition of $\delta^*$ (in (a)) does not really make any assumptions about $q$ then it makes sense to induct on the length of $w$.
This leads to another issue which is how $\delta^*$ is defined on a single character or even the empty string (for your base case), but you can probably assume it's defined similarly to the definition of $\delta^*$ given in class. The induction step should follow naturally because the definition of $\delta^*$ is inductive...
share|improve this answer
Sorry for type error. I take a picture of the question and the definition (_URL_.png) thanks! – Dyson Liu Oct 11 '12 at 10:25
You still need to update your original post with the work you've done. Honestly that question in the image is ill-specified in my head (maybe I'm crazy?). The intention seems relatively clear though, so you should still be able to work off it. Did you understand the basic approach I outlined in my answer? – roliu Oct 11 '12 at 22:12
Your Answer


KLM Royal Dutch Airlines KLM Royal Dutch Airlines
Historical sites & holiday destinations
Stroll through ancient sites
Looking for a destination with a fascinating past? Discover the most beautiful historical destinations in the world with KLM. Stroll around ancient excavated villages in Europe. Or spend a few days with your children exploring the American Museum of Natural History in New York where evolution comes to life. History fascinates!
Historic treasures
From the kilometres-long Chinese Wall in China to the stone city of Petra in Jordan: the world is full of historical sites. Take Italy for example. Visit famous cities such as Pompeii, unearthed after years hidden under a layer of ash. Visit the Colosseum in Rome or admire the Spanish Steps. Would you like to learn more about the Mayan culture? Mexico offers a wealth of historical sites. Visit the city of Chitzen Itza, full of famous Mayan ruins. This is one of the 7 modern wonders of the world! Expect to be surprised: book a flight to some amazing historical destinations now!
Learn from history
There are also important sites around the world that show the dark side of history. Concentration camp Auschwitz in Poland is one of the most moving monuments remembering victims of World War 2. Words cannot express what happened here. Another chilling monument can be found at the Killing Fields in Cambodia where horrific cruelties took place not that long ago. Fortunately there are also less sombre monuments, such as the world-famous temple complex packed with history at Angkor Wat.
Flights to an impressive historical holiday
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Groat (coin)
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For the hulled and crushed grains of various cereals, see groats. For the surname, see Groat (surname).
Edward I of England
AR Groat. _PHONE_.
The groat is the traditional name of a long-defunct English silver coin worth four English pennies, and also a Scottish coin originally worth fourpence, with later issues being valued at eightpence and one shilling.
The name has also been applied to any thick or large coin, such as the Groschen (grosso), a silver coin issued by Tyrol in 1271 and Venice in the 13th century, which was the first of this general size to circulate in the Holy Roman Empire and other parts of Europe. The immediate ancestor to the groat was the French gros tournois or groat of Tours, which was known as the groot (Dutch for "great" or "large") in the Netherlands.
The name groat also refers to a range of other European coins such as those of the Italian peninsula known as a grosso including the grosso of Venice and the Kraków grosz. Marco Polo referred to the groat in recounts of his travels to East Asia when describing the currencies of the Yuan Empire.[1] His descriptions were based on the conversion of 1 bezant = 20 groats = 133⅓ tornesel.[2]
David II of Scotland
++DAVID x REX x SCOTORVm Crowned bust left holding sceptre before; star at base of sceptre Outer circle: +DNS PTECTOR MS F LIBATOR MS - inner circle: VILL A ED InBV RGh Long cross quartered with of five points mullets.
AR Groat (3.11 g). Light coinage, _PHONE_. Edinburgh mint.
Henry VIII: Irish groat
Henry VIII minted these irish groats, crowned coat-of-arms over cross fourchee; mm: trefoil FRAnCIE ET hIBERnIE REX, crowned harp; crowned h and crowned R flanking (henricus Rex).
AR Groat (25 mm, 2.32 g, 12h). Second harp issue, as king of Ireland, _PHONE_. London mint (exported).
It was after the French silver coin had circulated in England that an English groat was first minted under King Edward I.
Scots groats were not issued until the reign of David II. Scots groats were originally also worth fourpence, but later issues were valued at eightpence and a shilling.[3][4]
Irish groats were minted first in 1425 and the last ones were minted under the reign of Elizabeth I of England. There were also two more issues, both emergency coinage.[5]
While strictly speaking, the English groat should have contained four pennyweights or 96 grains (6.2 grams) of sterling silver, the first ones issued weighed 89 grains (5.8 g) and later issues became progressively lighter. The weight was reduced to 72 grains (three pennyweights or 4.7 g) under Edward III, 60 grains (3.9 g) under Henry IV, and 48 grains (3.1 g) under Edward IV. From 1544 to 1560 (the weight being reduced to 32 grains (2.1 g) in 1559) the silver fineness was less than sterling, and after the 1561 issue they were not generally issued for circulation again for about a hundred years.
From the reigns of Charles II to George III, groats (by now often known as fourpences) were issued on an irregular basis for general circulation, the only years of mintage after 1786 being in 1792, 1795, and 1800. After this the only circulating issues were from 1836 to 1855, with proofs known from 1857 and 1862 and a colonial issue of 1888. These last coins had the weight further reduced to about 27 grains (1.9 grams) and were the same diameter as the silver threepenny pieces of the day although thicker. They also had Britannia on the reverse, while all other silver fourpenny pieces since the reign of William and Mary have had a crowned numeral "4" as the reverse, including the silver fourpenny Maundy money coins of the present. Some groats continued to circulate in Scotland until the 20th century.
At times in the past, silver twopenny coins have been called "half-groats."
The groat ceased to be minted in the United Kingdom in 1856, but in 1888 a special request was made for a colonial variety to be minted for use in British Guiana and the British West Indies. The groat remained in circulation in British Guiana right up until that territory adopted the decimal system in 1955.
Royal Navy chaplains[edit]
In the 1600s and 1700s, chaplains were employed in English Navy ships of war by the Captain, and paid out of a "groat" per month deducted from the wages of the seamen. The Navy's wages did not rise between 1653 and 1797 (see Spithead and Nore mutinies), during which time the Ordinary Seaman was paid 19 shillings, as was the chaplain.[6]
Cultural references[edit]
The word "groat" has entered into a number of English and Scottish expressions, many of them now archaic.
In the north of England, there is the saying "Blood without groats is nothing" meaning "family without fortune is worthless." The allusion is to black pudding, which consists chiefly of blood and oats formed into a patty. "Not worth a groat" is an old saying meaning "not worth a penny", i.e. worthless.
Benjamin Franklin, in his book, Necessary Hints gives the following thrifty advice:
He that spends a groat a day idly, spends idly above six pounds a year." (actually £6 plus one shilling eightpence)
In Beatrix Potter's The Tale of Squirrel Nutkin, there is the following riddle:
"Riddle me, riddle me, rot-tot-tote! A little wee man in a red red coat! A staff in his hand, and a stone in his throat; If you'll tell me this riddle, I'll give you a groat."
The answer is "a cherry."[7]
According to Hawkins' History of the Silver Coins of England,[8] groats were also known as "Joeys",
"so called from Joseph Hume, M.P., who strongly recommended the coinage for the sake of paying short cab-fares, etc."
This refers to the Victorian fourpenny piece. The mention of cab fares is related to the fact that the standard minimum was fourpence, so many passengers paid with a sixpenny piece, allowing the cabbie to keep the twopence change as a tip. The slang name "Joey" was transferred to the silver/cupronickel threepenny pieces in use in the first third of the twentieth century.
In A Little Princess by Frances Hodgson Burnett, Sara Crewe picks up a fourpenny piece from the street and uses it to buy buns. The original story was set in 1888.
John o' Groats, a place name in the north of Scotland, is not derived from "groat" but is a corruption of "Jan de Groot", the name of a Dutchman who migrated there in the reign of James IV.[9][10]
The monetary unit of Federation, the forerunner of the currently active Federation II text-based roleplaying game, was the groat.
Terry Pratchett's first book in the Moist von Lipwig series of novels, Going Postal, introduced a supporting character named Tolliver Groat.
As Anne Boleyn is being crowned in the film Anne of a Thousand Days, the gathered crowd give her a negative reception. Thomas Cromwell asks Thomas Boleyn: "How much did you pay them to cheer?", to which he responds: "A groat each".
Although not used in the monetary system of his fictional world of Westeros, author George R. R. Martin uses the term to refer to things of little worth in his series, A Song of Ice and Fire. For example, in the fourth book, A Feast for Crows, Cersei Lannister, in reference to Margaery Tyrell, thinks: "For half a groat she would have slapped the blushing bride right there upon the dais, in view of half the court."
See also[edit]
 1. ^ Yule, Henry; Cordier, Henri. The Travels of Marco Polo: The Complete Yule-Cordier Edition. Third edition (1903), revised and updated by Henri Cordier. Plain Label Books. p. 1226-27. (ISBN _PHONE_)
 2. ^ Henry Yule. The Travels of Marco Polo: The Complete Yule-Cordier Edition. Third edition (1903), revised and updated by Henri Cordier. Plain Label Books. p. 1229-30. (Note) (ISBN _PHONE_)
 3. ^ Mackay: Coin...
 4. ^ Stewart: Scottish...
 5. ^ Gr


text:
Colleges everywhere have work-study programs where students can work on campus and earn a bit of cash to pay for books, lab fees or whatever else they may need. You might think these programs are helping out lower-income students, but that is not necessarily the case.
According to The Hechinger Report, a lot of the work-study money (which is funded by federal taxpayers) goes to children of better-off families at expensive private universities. Much of this $1 billion in work-study funds goes to these "richer" students instead of students who perhaps need it more.
Approximately one in four work-study students come from families that earn more than $80,000 a year, and almost half of work-study students attend private, nonprofit universities and colleges. However, fewer than half meet the federal definition of financial need.
For more information on this story, click here.


text:
Sometimes one needs to simulate a Poisson point process on a disk. I know I often do. A disk or disc, depending on your spelling preference, is isotropic or rotationally-invariant, so a lot of my simulations of a Poisson point process happen in a circular simulation window when I am considering such a setting. For example, maybe you want to consider a single wireless receiver in a Poisson network of wireless transmitters, which only cares about the distance to a transmitter. Alternatively, maybe you want to randomly sprinkle a virtual cake. What to do? A Poisson point process on a disk is the answer.
I will simulate a Poisson point process with intensity \(\lambda>0\) on a disk with radius \(r>0\). The simulation steps are very similar to those in the previous post where I simulated a homogeneous Poisson point process on a rectangle, and I suggest going back to that post if you are not familiar with the material. The main difference between simulation on a rectangle and a disk is the positioning of the points, but first we'll look at the number of points.
Number of points
The number of points of a Poisson point process falling within a circle of radius \(r>0\) is a Poisson random variable with mean \(\lambda A\), where \(A=\pi r^2\) is the area of the disk. As in the rectangular case, this is the most complicated part of the simulation procedure. But as long as your preferred programming language can produce (pseudo-)random numbers according to a Poisson distribution, you can simulate a homogeneous Poisson point process on a disk.
To do this in MATLAB, use the poissrnd function with the argument \(\lambda A\). In R, it is done similarly with the standard function rpois. In Python, we can use either the scipy.stats.poisson or numpy.random.poisson function from the SciPy or NumPy libraries.
Locations of points
We need to position all the points randomly and uniformly on a disk. In the case of the rectangle, we worked in Cartesian coordinates. It is then natural that we now work in polar coordinates. I'll denote the angular and radial coordinate respectively by \(\theta\) and \(\rho\). To generate the random angular (or \(\theta\)) values, we simply produce uniform random variables between zero and one, which is what all standard (pseudo-)random number generators do in programming languages. But we then multiply all these numbers by \(2\pi\), meaning that all the numbers now fall between \(0\) and \(2\pi\).
To generate the random radial (or \(\rho\)) values, a reasonable guess would be to do the same as before and generate uniform random variables between zero and one, and then multiply them by the disk radius \(r\). But that would be wrong.
Before multiplying uniform random variables by the radius, we must take the square root of all the random numbers. We then multiply them by the radius, generating random variables between \(0\) and \(r\). (We must take the square root because the area element of a sector or disk is proportional to the radius squared, and not the radius.) These random numbers do not have a uniform distribution, due to the square root, but in fact their distribution is an example of the triangular distribution, which is defined with three real-valued parameters \(a\), \(b\) and \(c\), and for our case, set \(a=0\) and \(b=c=r\).
In summary, if \(U\) and \(V\) are two independent uniform random variables on \((0,1)\), then random point located uniformly on a disk of radius \(r\) has the polar coordinates \((r\sqrt(U), 2\pi V)\).
From polar to Cartesian coordinates
That's it. We have generated polar coordinates for points randomly and uniformly located in a disk. But to plot the points, often we have to convert coordinates back to Cartesian form. This is easily done in MATLAB with the pol2cart function. In languages without such a function, trigonometry comes to the rescue: \(x=\rho\cos(\theta)\) and \(y=\rho\sin(\theta)\).
Equal x and y axes
Sometimes the plotted points more resemble points on an ellipse than a disk due to the different scaling of the x and y axes. To fix this in MATLAB, run the command: axis square. In Python, set axis('equal') in your plot; see this page for a demonstration.
I'll now give some code in MATLAB, R and Python, which you can see are all very similar
%Simulation window parameters r=1; %radius of disk xx0=0; yy0=0; %centre of disk areaTotal=pi*r^2; %area of disk %Point process parameters lambda=100; %intensity (ie mean density) of the Poisson process %Simulate Poisson point process numbPoints=poissrnd(areaTotal*lambda);%Poisson number of points theta=2*pi*(rand(numbPoints,1)); %angular coordinates rho=r*sqrt(rand(numbPoints,1)); %radial coordinates %Convert from polar to Cartesian coordinates [xx,yy]=pol2cart(theta,rho); %x/y coordinates of Poisson points %Shift centre of disk to (xx0,yy0) xx=xx+xx0; yy=yy+yy0; %Plotting scatter(xx,yy); xlabel('x');ylabel('y'); axis square;
Note: it is a bit tricky to write "<-" in the R code (as it automatically changes to the html equivalent in the HTML editor I am using), so I have usually used "=" instead of the usual "<-".
_TAG_ window parameters r=1; _TAG_ of disk xx0=0; yy0=0; _TAG_ of disk areaTotal=pi*r^2; _TAG_ of disk _TAG_ process parameters lambda=100; _TAG_ (ie mean density) of the Poisson process _TAG_ Poisson point process numbPoints=rpois(1,areaTotal*lambda);_TAG_ number of points theta=2*pi*runif(numbPoints);_TAG_ of Poisson points rho=r*sqrt(runif(numbPoints));_TAG_ coordinates of Poisson points _TAG_ from polar to Cartesian coordinates xx=rho*cos(theta); yy=rho*sin(theta); _TAG_ centre of disk to (xx0,yy0) xx=xx+xx0; yy=yy+yy0; _TAG_ par(pty="s") plot(xx,yy,'p',xlab='x',ylab='y',col='blue');
Of course, with the amazing spatial statistics library spatstat, simulating a Poisson point process in R is even easier.
library("spatstat"); _TAG_ spatial statistics library _TAG_ Poisson "point pattern" object ppPoisson=rpoispp(lambda,win=disc(radius=r,centre=c(xx0,yy0))) plot(ppPoisson); _TAG_ point pattern object _TAG_ x/y values from point pattern object xx=ppPoisson$x; yy=ppPoisson$y;
Actually, you can even do it all in two lines: one for loading the spatstat library and one for creating and plotting the point pattern object.
Note: "lambda" is a reserved word in Python (and other languages), so I have used "lambda0" instead.
import numpy as np; _TAG_ package for arrays, random number generation, etc import matplotlib.pyplot as plt _TAG_ plotting _TAG_ window parameters r=1; _TAG_ of disk xx0=0; yy0=0; _TAG_ of disk areaTotal=np.pi*r**2; _TAG_ of disk _TAG_ process parameters lambda0=100; _TAG_ (ie mean density) of the Poisson process _TAG_ Poisson point process numbPoints = np.random.poisson(lambda0*areaTotal);_TAG_ number of points theta=2*np.pi*np.random.uniform(0,1,numbPoints); _TAG_ coordinates rho=r*np.sqrt(np.random.uniform(0,1,numbPoints)); _TAG_ coordinates _TAG_ from polar to Cartesian coordinates xx = rho * np.cos(theta); yy = rho * np.sin(theta); _TAG_ centre of disk to (xx0,yy0) xx=xx+xx0; yy=yy+yy0; _TAG_ plt.scatter(xx,yy, edgecolor='b', facecolor='none', alpha=0.5 ); plt.xlabel("x"); plt.ylabel("y"); plt.axis('equal');
The third edition of the classic book Stochastic Geometry and its Applications by Chiu, Stoyan, Kendall and Mecke details on page 54 how to uniformly place points on a disk, which they call the radial way. The same simulation section appears in the previous edition by Stoyan, Kendall and Mecke (Chiu didn't appear as an author until the current edition), though these books in general have little material on simulation methods. There is the book Spatial Point Patterns: Methodology and Applications with R written by spatial statistics experts Baddeley, Rubak and Turner, which covers the spatial statistics (and point process simulation) R-package spatstat.


text:
The DI2 Loop Powered process Indicator is a self powered 4-20mA input panel mounting process indicator which is housed in a 48 x 96mm impact resistant aluminium enclosure with weatherproof front. The instrument incorporates a 3.5 digit 12.5mm high LCD display with a wide viewing angle. It is user programmable in engineering units.
The DI2 instruments have been designed to accept an input signal of 4-20mA or 10-50mA and be powered from that signal. The input measurement is shown on a 12.5mm digit height 3.5 digit liquid crystal display (LCD).
They are user programmable in percent or engineering units for such process variables as flow, level, pressure and temperature.
The instruments have been designed to reject electrical interference that normally abounds in industrial environments.
The DI2 is supplied in a 48 x 96mm panel mount enclosure.
A 3.5 digit high contrast liquid crystal display (LCD) on a reflective background with a wide viewing angle and a viewing distance of 5 metres.
Three (3) position user selectable by dip switch for formats: 100.0; 10.00 and 1.000.
Most significant digit '1' and the three least significant digits blank.
0 to 2000 counts adjustable. For field adjustments the zero and span potentiometers are accessible from the rear of the instrument (DI2 only).
0.1% of reading +/- 1 count.
The operating power for the DI2 is obtained directly from the input signal current loop.
DI2 is 200 grams.
Panel mounting with a panel cut out of 93mm wide by 45mm high.
Led backlighting is available to operate from 24VDC.


text:
GREEN GUN LASERS ARE MUCH BRIGHTER
As many know, laser sights can be very beneficial; but there is one major flaw... ordinary red lasers can be next to impossible to see in most daylight conditions. The benefit of a green laser is that it is much more visible, allowing for it to be used anytime, day or night, indoors or outdoors, permitting you to track your target quicker and more accurately. Additionally, because green lasers are so much more visible to the human eye, you can actually see a very intimidating visible beam in low-light conditions.
The Difference is Clear
Which is more visible to you? On the left we see a traditional red laser sight, compared to the green Viridian in broad daylight. The lasers were at a distance of 25 feet from the wall.
On the left you can see how visible the beam can actually get during dark or dimmer conditions.
Shown to the left is an additional day shot, which again shows the dramatic difference.
Why Green Lasers are More Visible
Green is closer to the center of the visible spectrum, at 532 Nanometers, so it's easier for our eyes to perceive the color vs. a red laser at 635 Nanometers. In fact, a green laser can appear as much as 50 times brighter than the red equivalent and as can be seen from the below charts 532 nm is the ideal wavelength to maximize visibility during day or night.
In Daytime Conditions the human eye has maximum sensitivity
at the 555 nm wavelength
In Nighttime Conditions the human eye has maximum sensitivity
of 512 nm wavelength


09/08/2012
What is the "error 500: Internal error"?
Error 500
Josep Sanz
The 500 error is an error generated by the server when it encounters an error condition that can not resolve automatically. That is, if a file is not found, the error is 404 (Not found), if you can not lists a directory, the error 403 will be launched (Forbidden). For errors that do not have an explicit definition, will raise the error 500 (Internal error). This error usually occurs in Apache: when used in the .htaccess file some unsupported directives. in some hostings…
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* 1 beyond buffer pointed to by utf */
 UV uv; /* Note: a UV, not a U8, not a char */
 STRLEN len; /* length of character in bytes */
 if (!UTF8_IS_INVARIANT(*utf))
 /* Must treat this as UTF-8 */
 uv = utf8_to_uvchr_buf(utf, utf_end, &len);
 else
 /* OK to treat this character as a byte */
 uv = *utf;
You can also see in that example that we use "utf8_to_uvchr_buf" to get the value of the character; the inverse function "uvchr_to_utf8" is available for putting a UV into UTF-8:
 if (!UVCHR_IS_INVARIANT(uv))
 /* Must treat this as UTF8 */
 utf8 = uvchr_to_utf8(utf8, uv);
 else
 /* OK to treat this character as a byte */
 *utf8++ = uv;
You must convert characters to UVs using the above functions if you're ever in a situation where you have to match UTF-8 and non-UTF-8 characters. You may not skip over UTF-8 characters in this case. If you do this, you'll lose the ability to match hi-bit non-UTF-8 characters; for instance, if your UTF-8 string contains "v196.172", and you skip that character, you can never match a "chr(200)" in a non-UTF-8 string. So don't do that!
(Note that we don't have to test for invariant characters in the examples above. The functions work on any well-formed UTF-8 input. It's just that its faster to avoid the function overhead when it's not needed.)
How does Perl store UTF-8 strings?
Currently, Perl deals with UTF-8 strings and non-UTF-8 strings slightly differently. A flag in the SV, "SVf_UTF8", indicates that the string is internally encoded as UTF-8. Without it, the byte value is the codepoint number and vice versa. This flag is only meaningful if the SV is "SvPOK" or immediately after stringification via "SvPV" or a similar macro. You can check and manipulate this flag with the following macros:
 SvUTF8(sv)
 SvUTF8_on(sv)
 SvUTF8_off(sv)
This flag has an important effect on Perl's treatment of the string: if UTF-8 data is not properly distinguished, regular expressions, "length", "substr" and other string handling operations will have undesirable (wrong) results.
The problem comes when you have, for instance, a string that isn't flagged as UTF-8, and contains a byte sequence that could be UTF-8 --- especially when combining non-UTF-8 and UTF-8 strings.
Never forget that the "SVf_UTF8" flag is separate from the PV value; you need to be sure you don't accidentally knock it off while you're manipulating SVs. More specifically, you cannot expect to do this:
 SV *sv;
 SV *nsv;
 STRLEN len;
 char *p;
 p = SvPV(sv, len);
 frobnicate(p);
 nsv = newSVpvn(p, len);
The "char*" string does not tell you the whole story, and you can't copy or reconstruct an SV just by copying the string value. Check if the old SV has the UTF8 flag set (after the "SvPV" call), and act accordingly:
 p = SvPV(sv, len);
 is_utf8 = SvUTF8(sv);
 frobnicate(p, is_utf8);
 nsv = newSVpvn(p, len);
 if (is_utf8)
 SvUTF8_on(nsv);
In the above, your "frobnicate" function has been changed to be made aware of whether or not it's dealing with UTF-8 data, so that it can handle the string appropriately.
Since just passing an SV to an XS function and copying the data of the SV is not enough to copy the UTF8 flags, even less right is just passing a "char *" to an XS function.
For full generality, use the "DO_UTF8" macro to see if the string in an SV is to be treated as UTF-8. This takes into account if the call to the XS function is being made from within the scope of "use bytes". If so, the underlying bytes that comprise the UTF-8 string are to be exposed, rather than the character they represent. But this pragma should only really be used for debugging and perhaps low-level testing at the byte level. Hence most XS code need not concern itself with this, but various areas of the perl core do need to support it.
And this isn't the whole story. Starting in Perl v5.12, strings that aren't encoded in UTF-8 may also be treated as Unicode under various conditions (see ''ASCII Rules versus Unicode Rules'' in perlunicode). This is only really a problem for characters whose ordinals are between 128 and 255, and their behavior varies under ASCII versus Unicode rules in ways that your code cares about (see ''The ''Unicode Bug"" in perlunicode). There is no published API for dealing with this, as it is subject to change, but you can look at the code for "pp_lc" in pp.c for an example as to how it's currently done.
How do I convert a string to UTF-8?
If you're mixing UTF-8 and non-UTF-8 strings, it is necessary to upgrade the non-UTF-8 strings to UTF-8. If you've got an SV, the easiest way to do this is:
 sv_utf8_upgrade(sv);
However, you must not do this, for example:
 if (!SvUTF8(left))
 sv_utf8_upgrade(left);
If you do this in a binary operator, you will actually change one of the strings that came into the operator, and, while it shouldn't be noticeable by the end user, it can cause problems in deficient code.
Instead, "bytes_to_utf8" will give you a UTF-8-encoded copy of its string argument. This is useful for having the data available for comparisons and so on, without harming the original SV. There's also "utf8_to_bytes" to go the other way, but naturally, this will fail if the string contains any characters above 255 that can't be represented in a single byte.
How do I compare strings?
''sv_cmp'' in perlapi and ''sv_cmp_flags'' in perlapi do a lexigraphic comparison of two SV's, and handle UTF-8ness properly. Note, however, that Unicode specifies a much fancier mechanism for collation, available via the Unicode::Collate module.
To just compare two strings for equality/non-equality, you can just use "memEQ()" and "memNE()" as usual, except the strings must be both UTF-8 or not UTF-8 encoded.
To compare two strings case-insensitively, use "foldEQ_utf8()" (the strings don't have to have the same UTF-8ness).
Is there anything else I need to know?
Not really. Just remember these things:
*
There's no way to tell if a "char *" or "U8 *" string is UTF-8 or not. But you can tell if an SV is to be treated as UTF-8 by calling "DO_UTF8" on it, after stringifying it with "SvPV" or a similar macro. And, you can tell if SV is actually UTF-8 (even if it is not to be treated as such) by looking at its "SvUTF8" flag (again after stringifying it). Don't forget to set the flag if something should be UTF-8. Treat the flag as part of the PV, even though it's not --- if you pass on the PV to somewhere, pass on the flag too.
*
If a string is UTF-8, always use "utf8_to_uvchr_buf" to get at the value, unless "UTF8_IS_INVARIANT(*s)" in which case you can use *s.
*
When writing a character UV to a UTF-8 string, always use "uvchr_to_utf8", unless "UVCHR_IS_INVARIANT(uv))" in which case you can use "*


DEV Community
Cover image for Implementing a Simple LRU Cache in JavaScript
Sean Welsh Brown
Sean Welsh Brown
Posted on
Implementing a Simple LRU Cache in JavaScript
In your travels as a software engineer, you're likely to come across instances where every possible data structure gets a chance to shine. One in particular doesn't get quite as much spotlight as the others, but can be just as useful (if not more so) in certain situations. That data structure in question is the LRU Cache.
What is an LRU Cache?
An LRU Cache, or Least Recently Used Cache, is a data structure that stores information in the order that it has most recently been added or accessed.
A popular analogy is a clothes rack in a closet: as clothes are worn and hung back up, they go on the right side of the rack. As time goes on, one can easily tell which clothes haven't been worn in a longer period of time by looking at the left side of the rack.
Why would I want to use one?
The main advantage of using an LRU Cache versus other data structures to store information comes in the form of added functionality.
A Cache in computer science terms can be thought of as a block of recently used data stored in a quickly accessible location in memory, resulting in faster performance when that same data is repeatedly pulled up.
If we consider an LRU Cache, it could be useful in an application that has users searching through a database for information. Normally every time a user looks something up, the app would ping its database with a request, taking precious time to do so. If, however, we store the most recently (or most commonly) searched-for items in an LRU cache, we can quickly check to see if the searched-for item exists in the cache, and if so we can retrieve it in significantly less time! Super useful.
Sounds great, how do we build one?
I'm glad you asked! Traditionally LRU Caches are built by combining a Hash Map with a Doubly Linked List, in order to maintain fast lookup of items and retrieval of most-recently-used and least-recently-used items in constant O(1) time.
However, if quickly implementing an LRU Cache from scratch in a small scale project is of interest to you, then one can be built out simply using nothing more than a JavaScript Class and a Map() object, at a cost to retrieval runtime.
The Least/Most Recently Used functionality will remain the same, which in practice is the key aspect of the data structure. If you're interested in learning how to create this version of an LRU Cache, then read on!
1. Establish the Class and Constructor
We'll be building out our LRU Cache using a JavaScript ES6 class, like so:
class LRUCache {
}
Within this class, we'll set a constructor so that every instance of an LRU Cache maintains the same structure. Our cache will take in a capacity as an argument, which will set the maximum size that our cache can grow to before we remove the least recently used item from its storage in order to save space and keep the structure organized.
We'll use this constructor to also establish the cache itself, using a JavaScript Map object:
class LRUCache {
 constructor(capacity) {
 this.cache = new Map();
 this.capacity = capacity;
 }
}
The reason we're using a Map object here is that JavaScript Maps maintain the order in which keys and values have been inserted. This does most of the work for us!
2. Build out the Get and Put methods of the Cache
Now, we're going to implement our two vital functions within the class: Get and Put, which will retrieve a value and insert a key/value pair into the cache respectively.
Let's start with Get:
class LRUCache {
 constructor(capacity) {
 this.cache = new Map();
 this.capacity = capacity;
 }
 // Implementing Get method
 get(key) {
 if (!this.cache.has(key)) return undefined;
 let val = this.cache.get(key);
 this.cache.delete(key);
 this.cache.set(key, val);
 return val;
 }
}
Let's break down what we just did above.
 1. We check to see if the key exists in our Map. If it doesn't, we return "undefined" (this could be any return value that represents a failed retrieval, such as -1 or an error message.)
 2. Next we declare a variable "val", get the value associated with that key, and assign it to the variable.
 3. We delete that key/value pair from our cache, and then set it again. Since our map keeps the order in which we insert things, this puts our retrieved key/value pair back at the front (most recently used) spot.
 4. We return the value for use in our program wherever this method was called.
And that's all there is to the Get method!
Now, we'll implement our Put method:
class LRUCache {
 constructor(capacity) {
 this.cache = new Map();
 this.capacity = capacity;
 }
 get(key) {
 if (!this.cache.has(key)) return -1;
 let val = this.cache.get(key);
 this.cache.delete(key);
 this.cache.set(key, val);
 return val;
 }
 // Implementing Put method
 put(key, value) {
 this.cache.delete(key);
 if (this.cache.size === this.capacity) {
 this.cache.delete(this.cache.keys().next().value);
 this.cache.set(key, value);
 } else {
 this.cache.set(key, value);
 }
 }
}
Let's break it down into steps:
 1. The first line checks if the key already exists in the Map and deletes it if so; calling .delete() either deletes the key/value pair if it exists OR returns undefined and continues if it doesn't.
 2. If our cache is currently at its maximum capacity ( cache.size === this.capacity ), we delete our least recently used key/value pair by using this.cache.keys().next().value to get the first key of the Map using an iterator object and passing it as an argument to this.cache.delete() . We then set a new key/value pair in the cache using the arguments passed into the Put method.
 3. If we're not currently at maximum capacity, we simply add the new key/value pair as normal.
And there's our Set method!
3. Implement getLeastRecent and getMostRecent methods
At this point we've created the fundamental functionality of an LRU Cache, but there's one step to go in order to have a complete data structure. We might want to retrieve the Least Recently Used (LRU) or Most Recently Used (MRU) values!
In order to do so, we're going to convert our Map into an array, then retrieve the first (LRU) and last (MRU) values of the array respectively:
class LRUCache {
 constructor(capacity) {
 this.cache = new Map();
 this.capacity = capacity;
 }
 get(key) {
 if (!this.cache.has(key)) return -1;
 let val = this.cache.get(key);
 this.cache.delete(key);
 this.cache.set(key, val);
 return val;
 }
 put(key, value) {
 this.cache.delete(key);
 if (this.cache.size === this.capacity) {
 this.cache.delete(this.cache.keys().next().value);
 this.cache.set(key, value);
 } else {
 this.cache.set(key, value);
 }
 }
 // Implement LRU/MRU retrieval methods
 getLeastRecent() {
 return Array.from(this.cache)[0];
 }
 getMostRecent() {
 return Array.from(this.cache)[this.cache.size - 1];
 }
}
And there we go! If you wanted to, you could use this same Array-from-Map concept to find second-least-recently-used, third-most-recently-used, etc.
That's our LRU Cache!
If you've read this far, thanks so much for taking the time to check out my post!
I hope it's been helpful to those of you trying to learn and understand data structures, or those of you trying to implement them in JavaScript. 😄
Discussion (6)
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bias profile image
Tobias Nickel
when get a key and it is not there, I would return undefined or an error. -1 could also be the value. It reminds me to the time when we needed if (array.indexOf(needle)===-1)；{...} and today we have array.includes.
It is very interesting how you are using the iterator from cache.keys().
also, it would be interesting to add a time-to-life, but that can be a good homework 😊
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seanwelshbrown profile image
Sean Welsh Brown Author
Thanks for your feedback Tobias! I


text:
This report describes the results of a study in response to the FY2014 Vehicle Technologies program DE-FOA-_PHONE_ solicitation for fuel economy improvement of cars and trucks (Area of interest 11: powertrain friction and wear reduction). It stated, "parasitic losses within vehicle engines and drivetrains are responsible for approximately two million barrels of oil consumption per day in the US. These losses are caused by friction between components, movement of components through fluids, and movement of fluids through components". The objective of the study is to develop and demonstrate friction and wear reduction technologies for light duty vehicles that improve fuel efficiency of legacy vehicles by at least 2%, without adverse impacts on vehicle performance or durability.
- Contact us


text:
Domain-Specific Modeling with MetaEdit+: 10 Times Faster Than UML
Domain-Specific Modeling (DSM) raises the level of abstraction beyond programming by specifying the solution directly using domain concepts. The final products are generated from these high-level specifications. This automation is possible because both the language and generators must fit the requirements of only one company and one domain. In this paper we describe why DSM is faster and explain how to build a DSM language and generator using MetaEdit+.


Tag Archives: fuel
Dirty shipping: Low sulfur standards in marine fuels
The most energy efficient way to move things around the world is stick something in a 40 by 8 foot foot shipping container that is hauled to port by an 18 wheel truck and loaded on a gigantic container ship. These ships piled high with goods from all over the world can be as large as 400 by 59 meters and can carry up to 9000 of these 40 foot shipping containers at a time.
These ships are often designed to burn the dirtiest type of fuel, which is the residual sludge left over after oil distillation that is called heavy fuel oil. This sludge is so viscous that it has to be heated just to pump it into the ship engines to be burned. Most large ships operating today use a type of fuel known as intermediate fuel oil, which is a mixture of heavy fuel oil which has a viscosity up to 700 mm2 per second and marine gas oil, which is No. 2 distillate with a viscosity between 1.5 and 6 mm2/sec. This intermediate fuel oil is generally sold as IFO180 or IFO360, meaning it has a viscosity of 180 mm2/sec or 360 mm2/sec.
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You are viewing documentation for a release that is no longer supported. The latest supported version of version 3 is [3.11]. For the most recent version 4, see [4]
You are viewing documentation for a release that is no longer supported. The latest supported version of version 3 is [3.11]. For the most recent version 4, see [4]
Before you begin
Configuring authorization for Google Cloud Platform
Roles
Configuring GCP for OpenShift Container Platform requires the following GCP role:
roles/owner
Needed for creating service accounts, cloud storage, instances, images, templates, Cloud DNS entries, and to deploy load balancers and health checks.
delete permissions might also be required if the user is expected to redeploy the environment during testing phases.
You can also create a service account to avoid using personal users when deploying GCP objects.
See the Understanding roles section of the GCP documentation for more information, including steps for how to configure roles.
Scopes and service accounts
GCP uses scopes to determine if an authenticated identity is authorized to perform operations within a resource. For example, if application A with a read-only scope access token can only read, while application B with a read-write scope access token can read and modify data.
The scopes are defined at the GCP API level as _URL_
You can specify scopes using the --scopes=[SCOPE,…] option when creating instances, or you can use the --no-scopes option to create the instance without scopes if you don't want the instance accessing the GCP API.
All GCP projects include a default [PROJECT_NUMBER]_EMAIL_ service account with project editor permissions.
By default, a newly created instance is automatically enabled to run as the default service account with the following access scopes:
You can specify another service account with the --service-account=SERVICE_ACCOUNT option when creating the instance, or explicitly disabling service accounts for the instance using the --no-service-account option using the gcloud CLI.
Google Compute Engine objects
Integrating OpenShift Container Platform with Google Compute Engine (GCE) requires the following components or services.
A GCP project
A GCP project is the base level organizing entity that forms the basis for creating, enabling, and using all GCP services. This includes managing APIs, enabling billing, adding and removing collaborators, and managing permissions.
Project IDs are unique identifiers, and project IDs must be unique across all of Google Cloud Engine. This means you cannot use myproject as a project ID if someone else has created a project with that ID before.
Billing
You cannot create new resources unless billing is attached to an account. The new project can be linked to an existing project or new information can be entered.
Cloud identity and access management
Deploying OpenShift Container Platform requires the proper permissions. A user must be able to create service accounts, cloud storage, instances, images, templates, Cloud DNS entries, and deploy load balancers and health checks. Delete permissions are also helpful in order to be able to redeploy the environment while testing.
You can create service accounts with specific permissions, then use them to deploy infrastructure components instead of regular users. You can also create roles to limit access to different users or service accounts.
GCP instances use service accounts to allow applications to call GCP APIs. For example, OpenShift Container Platform node hosts can call the GCP disk API to provide a persistent volume to an application.
Access control to the various infrastructure, service resources, and fine-grained roles are available using the IAM service. For more information, see the Access cloud overview section of the GCP documentation.
SSH keys
GCP injects SSH public keys as authorized keys so you can log in using SSH in the created instances. You can configure the SSH keys per instance or per project.
You can use existing SSH keys. GCP metadata can help with storing the SSH keys that are injected at boot time in the instances to allow SSH access.
GCP regions and zones
GCP has a global infrastructure that covers regions and availability zones. While deploying OpenShift Container Platform in GCP on different zones can help avoid single-point-of-failures, there are some caveats regarding storage.
GCP disks are created within a zone. Therefore, if a OpenShift Container Platform node host goes down in zone "A" and the pods move to zone "B", the persistent storage cannot be attached to those pods because the disks are in a different zone.
Deploying a single zone of multizone OpenShift Container Platform environment is an important decision to make before installing OpenShift Container Platform. If deploying a multizone environment, the recommended setup is to use three different zones in a single region.
External IP address
So that GCP instances can communicate with the Internet, you must attach an external IP address to the instance. Also, an external IP address is required to communicate with instances deployed in GCP from outside the Virtual Private Cloud (VPC) Network.
Requiring an External IP address for internet access is a limitation of the provider. You can configure firewall rules to block incoming external traffic in instances if not needed.
Cloud DNS
GCP cloud DNS is a DNS service used to publish domain names to the global DNS using GCP DNS servers.
The public cloud DNS zone requires a domain name that you purchased either through Google's "Domains" service or through a third-party provider. When you create the zone, you must add the name servers provided by Google to the registrar.
See the GCP documentation on Cloud DNS for more information.
GCP VPC networks have an internal DNS service that automatically resolves internal host names.
The internal fully qualified domain name (FQDN) for an instance follows the [HOST_NAME].c.[PROJECT_ID].internal format.
See the GCP documentation on Internal DNS for more information.
Load balancing
The GCP load balancing service enables the distribution of traffic across multiple instances in the GCP cloud.
There are five types of Load Balancing:
HTTPS and TCP proxy load balancing are the only options for using HTTPS health checks for master nodes, which checks the status of /healthz.
Because HTTPS load balancing requires a custom certificate, this implementation uses TCP Proxy load balancing to simplify the process.
See the GCP documentation on Load balancing for more information.
Instances sizes
A successful OpenShift Container Platform environment requires some minimum hardware requirements:
Table 1. Instances sizes
Role Size
Master
n1-standard-8
Node
n1-standard-4
GCP allows you to create custom instance sizes to fit different requirements. See Creating an Instance with a Custom Machine Type for more information, or see Machine types and OpenShift Container Platform Minimum Hardware Requirements for more information about instance sizes.
Storage Options
By default, each GCP instance has a small root persistent disk that contains the operating system. When applications running on the instance require more storage space, you can add additional storage options to the instance:
 - Standard persistent disks
 - SSD persistent disks
 - Local SSDs
 - Cloud storage buckets
For more information, see the GCP documentation on Storage options.
Configuring OpenShift Container Platform for GCE
You can configure OpenShift Container Platform for GCE in two ways:
Option 1: Configuring OpenShift Container Platform for GCP using Ansible
You can configure OpenShift Container Platform for Google Compute Platform (GCP) by modifying the Ansible inventory file at installation time or after installation.
Procedure
 1. At minimum, you must define the openshift_cloudprovider_kind, openshift_gcp_project and openshift_gcp_prefix parameters, as well as the optional openshift_gcp_multizone for multizone deployments and openshift_gcp_network_name if you are not using the default network name.
 Add the following section to the Ansible inventory file at installation to configure your OpenShift Container Platform environment for GCP:
 [OSEv3:vars]
 openshift_cloudprovider_kind=gce
 openshift_gcp_project=<projectid> (1)
 openshift_gcp_prefix=<uid> (2)
 openshift_gcp_multizone=False (3)
 openshift_gcp_network_name=<network name> (4)
 1 Provide the GCP project ID where the existing instances are running. This ID is generated when you create the project in the Google Cloud Platform Console.
 2 Provide a unique string to identify each OpenShift Container Platform cluster. This must be unique across GCP.
 3 Optionally, set to True to trigger multizone deployments on GCP. Set to False by default.
 4 Optionally, provide the network name if not using default network.
 Installing with Ansible also creates and configures the following files to fit your GCP environment:
 - /etc/origin/cloudprovider/gce.conf
 - /etc/origin/master/master-config.yaml
 - /etc/origin/node/node-config.yaml
 2. If you are running load balancer services using GCP, the Compute Engine VM node instances require the ocp suffix. For example, if the value of the openshift_gcp_prefix parameter is set to myclust


text:
The Benefits of Joining a Syndicate for Big Rewards
Are you tired of playing the lottery alone and never winning big? It's time to consider joining a syndicate for big rewards. Syndicates are groups of people who pool their money together to buy more lottery tickets, increasing their chances of winning. In this article, we will explore the benefits of joining a syndicate and how it can lead to big rewards.
One of the most significant advantages of joining a syndicate is the increased probability of winning. When you play the lottery alone, your chances of hitting the jackpot are slim. However, by joining a syndicate, you are pooling your resources with others, allowing you to purchase more tickets. With more tickets, your odds of winning increase significantly. It's a simple concept, but it can make a world of difference in your lottery experience.
Not only does joining a syndicate increase your chances of winning, but it also allows you to play more games. Lottery tickets can be expensive, especially if you want to play multiple games or participate in different draws. By joining a syndicate, you can split the cost of tickets with other members, enabling you to play more games without breaking the bank. This means more opportunities to win big rewards and potentially change your life forever.
Another benefit of joining a syndicate is the sense of community it provides. Playing the lottery can be a solitary activity, but being part of a syndicate brings people together who share a common goal – winning big. You can discuss strategies, share excitement, and support each other through the ups and downs of the lottery journey. It's a great way to connect with like-minded individuals and build lasting friendships.
In addition to the increased chances of winning and the sense of community, joining a syndicate also allows you to participate in larger lottery draws. Some lotteries offer special promotions or exclusive draws that are only available to syndicates. These draws often have bigger jackpots and better odds of winning. By joining a syndicate, you gain access to these exclusive opportunities, giving you a shot at even bigger rewards.
One concern that some people may have when considering joining a syndicate is the fear of having to share the winnings. While it's true that you will have to split the prize with other members, the potential rewards far outweigh this drawback. Winning a smaller share of a big jackpot is still a life-changing event. Plus, the joy of winning together and celebrating as a group can be incredibly fulfilling.
In conclusion, joining a syndicate is a smart move for anyone looking to increase their chances of winning big rewards in the lottery. By pooling your money with others, you can buy more tickets, play more games, and participate in exclusive draws. The sense of community and the potential for life-changing winnings make joining a syndicate an exciting and rewarding experience. So, why play the lottery alone when you can join a syndicate and increase your odds of hitting the jackpot? Take the leap and join a syndicate today – your big reward could be just around the corner.


text:
MIAMI (CBS4) — Florida's gopher tortoise population deserves to be added to the nation's list of endangered and threatened species but funding shortages could delay the listing for years, federal wildlife officials said on Tuesday.
There is sufficient scientific data to list the gopher tortoise as threatened in parts of Florida, Alabama, Georgia, and South Carolina, said Cindy Dohner, the U.S. Fish and Wildlife Service's regional director for the Southeast.
"But we do not have the resources to pursue the listing process at this time," she told reporters during a conference call, noting the process can cost $300,000 or more.
The gopher tortoise, which is sandy brown in color and can grow to up to 15 pounds, will instead join a list of 251 other species designated as candidates for federal protection, meaning wildlife managers acknowledge their survival is in danger but they don't have the money to do anything about it.
It's unclear how long it will take to draw up a full recovery plan, which includes mapping out critical habitat, much of which is in Florida, particularly Central and North Florida. State wildlife managers designated the turtle as a "threatened" species in 2007 and, after public outcry, banned a cold-hearted practice that had allowed developers to bury more than 70,000 of them alive.
The tortoise is threatened by habitat loss, herbicides used in forestry and other factors, federal officials said.
Scientists consider the turtle, which can live a half century, a "keystone species" because its deep network of burrows help support some 360 other species, including snakes, rodents, skunks and rabbits. But some landowners consider it a nuisance because they see it as a potentially expensive hurdle to development plans.
Under a Florida Fish and Wildlife Conservation Commission plan adopted in 2008, builders must obtain a permit to build in gopher tortoise habitat and agree to relocate any found. As an incentive, the state will reduce permit costs if developers place them in high-quality habitat or set aside other areas for turtle use. It's illegal to kill or move the tortoises or eggs without a state permit.
(©2011 CBS Local Media, a division of CBS Radio Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed. CBS4 news partner The Miami Herald contributed material for this report)


text:
This paper describes the use of indirect microwave holographic together with inverse scattering techniques for the reconstruction of the dielectric properties of unknown objects. The use of indirect microwave holography enables the complex field scattered from the object under imaging to be recovered from intensity-only scalar microwave measurements and therefore removes the requirement of using expensive vector measurement equipment. This significantly reduces the cost of the imaging system and simplifies the hardware implementation. Following the successful implementation of indirect holography method for shape and position reconstruction, we have explored an algorithm which combines indirect holography method and CSI method to solve the phaseless data reconstruction problem. Results presented here indicate that the material properties of composite dielectric objects can be accurately reconstructed using scalar measurements from indirect holography.
|Title of host publication||Proceedings of 2014 Mediterranean Microwave Symposium (MMS2014)|
|Place of Publication||Piscataway, NJ|
|Publication status||Published - 2014|
|Event||14th Mediterranean Microwave Symposium (MMS) - Marrakech|
Duration: 1 Jan 2014 → …
|Conference||14th Mediterranean Microwave Symposium (MMS)|
|Period||1/01/14 → …|


text:
Difference between Merge Raster Layers and Build Virtual Raster in QGis?Geographic Information Systems
What is a virtual raster QGIS?
A virtual raster (VRT) is a special type of file that references one or more existing raster datasets and combines them into a single virtual layer.
Can you merge raster layers in QGIS?
QGIS uses the the GDAL merge tool, which is a very fast and efficient tool, to merge multiple raster layers. To merge raster layers in QGIS open the Merge tool from the raster menu, then select the raster layers to merge together, specify an output location and click run.
How do I merge raster in QGIS?
QGIS: Raster Merging
- In the QGIS Browser Panel, select the GeoTiffs you want to merge and right click to add them to the main window.
- Select Raster > Miscellaneous > Merge.
- In the Merge dialogue window, for Input files, browse to your directory containing your GeoTiff tiles.
How do I combine two raster layers?
Open the Mosaic To New Raster tool by navigating to ArcToolbox > Data Management Tools > Raster > Raster Dataset.
- Insert the raster files.
- Select the output location.
- Specify a name and extension for the output.
- Specify the pixel type.
- Specify the number of bands.
What is a virtual raster?
A virtual raster is a special type of raster whose pixel values are created upon request during data processing or visualization. Its memory footprint includes a reference to a source raster along with details of how the source pixel values will be modified in order to create new pixels.
What are the two types of raster data?
There are two types of raster data: continuous and discrete. An example of discrete raster data is population density. Continuous data examples are temperature and elevation measurements. There are also three types of raster datasets: thematic data, spectral data, and pictures (imagery).
What is the difference between merge and mosaic raster?
In the case of MERGE, the sequence of input grids determines the values assigned to cells, giving priority to those entered first. For MOSAIC, overlapping areas were blended to make a smooth transition and the sequence of entry is irrelevant (if on each overlapping area no more than two grids intersect).
What is merge in QGIS?
QGIS Introduction: Merge Shapefiles
Merging data can be necessary when you obtain vector data from multiple sources. In QGIS, the data need to be the data same type (i.e. all polygons or all points) and in one folder with no other data.
How do I merge layers in QGIS?
Quote from video: Okay often in qgis we might may find ourselves with a situation where we have four different layers. These are just countries and they just come in my background mapping. And so it's not really that
What is a virtual field in QGIS?
Virtual fields are a pure QGIS concept. The data provider (your database) does not know the slightest bit about their existence. Virtual fields are just put "on top of" the real data, their values are temporarily regenerated by QGIS every time they are required somewhere.
What is a virtual layer in QGIS?
A special kind of vector layer allows you to define a layer as the result of an advanced query, using the SQL language on any number of other vector layers that QGIS is able to open. These layers are called virtual layers: they do not carry data by themselves and can be seen as views to other layers.
What is VRT in QGIS?
Description. Builds a VRT (Virtual Dataset) that is a mosaic of the list of input GDAL-supported rasters. With a mosaic you can merge several raster files. The algorithm is derived from the GDAL buildvrt utility.
- Compaction in the Rock Cycle: Understanding the Process Behind Sedimentary Rock Formation
- Crystallization in the Water Cycle: A Fundamental Process in Water Distribution and Purification
- Understanding Crystallization in the Rock Cycle: A Fundamental Process in Rock Formation
- SQL Server to Google Maps
- Stereo-pair Image Registration
- Extracting Lat/Lng from Shapefile using OGR2OGR/GDAL
- Constructing query in Nominatim
- In Ogr2OGR: what is SRS?
- Identifying port numbers for ArcGIS Online Basemap?
- Remove unwanted regions from map data QGIS
- Waiting for Vector & WFS loading
- Adding TravelTime as Impedance in ArcGIS Network Analyst?
- Listing total number of features into an ArcGIS Online feature pop-up
- Tile large raster file in QGIS


text: 1347 Ha size in total (2 portions) 700 Ha High Potential Dry Lands Grazing camps - 477Ha Pan - 137 Ha Wasteland and Homestead - 33Ha Average rainfall between 350mm and 400mm Water is obtained from 4 equipped boreholes and stored in cement or zinc dams and 1 earth dam. Water appears to be more than adequate with the necessary watering infrastructure in place. Bio resource information indicates that the average carrying capacity for this area is around 7 Ha per large stock unit without supplementary feeding. The soils consist of a combination of medium/high and high potential soils. Sandy loam soils typical of the area with the long term yields on maize of >5,5t per hectare. The farm is improved a modern dwelling, with related stores and outbuildings. The buildings are functional and contributes to the overall production of the farm. Sundry improvements consist of dams, fences, boreholes etc. Viewing by appointment only.


Sunburnt Aloe Vera Plant from Too Much Sun – Signs + Fixes
One of the most overlooked habits most people growing an aloe vera plant do is letting it bathe in the scorching sun for more extended periods. While the sun is essential for the healthy growth of aloe, too much of it can burn its leaves. Like any other houseplant, an aloe is sensitive to sudden temperature changes and negligence.
Signs for a sunburnt aloe vera plant
A healthy aloe vera should be fleshy, firm, and green. However, determine if your aloe's leaves are wilting or changing color due to overwatering, pests and diseases, potting shock, or too much sun because the symptoms are almost similar. If you suspect that sun scorch is the problem, watch out for the signs.
Here are the signs of a sunburnt aloe plant:
Burn spots on the leaves
Sunburnt aloe plants have burn spots that may appear darkish brown, greyish or black depending on how much of the sun's intensity it has received. Some spots may protrude on the surface of the leaves.
If you notice this symptom, it's time you removed it away from the sun.
Brown leaf tips
The green-colouring matter should be evenly distributed from the base to the tip of the leaf. A sign of brown to fading green signifies sunburn. It's the plant's way of crying for help, prompting you to make a few adjustments.
Even browning of leaves
While browning leaves may be a sign of overwatering or pests and diseases, sunburn can also cause. It's easy to know if the latter is the culprit, mainly if you haven't watered your plant for a while and you're sure that pests or diseases haven't attacked it.
For the first few days, the aloe plant's leaves will start turning yellow but will quickly progress into a darker shade to indicate that the leaves are losing too much water due to sunburn.
Total soil dryness
Take note that soil gets drier during summer and winter. If the soil in your garden or pot is visibly drier than the rest of the days, chances are there is no moisture left in the soil for the plant to feed on.
Therefore, water the roots through the soil at least twice a month during the summer months because the high temperatures increase water loss through leaves and even evaporation from the soil in the pot. The plant doesn't need too much watering during winter.
Droopy and wilting leaves
Aloe vera leaves might lose moisture causing them to become droopy when exposed to too much sunlight. At this point, your succulent is thirsty and if you don't provide water, it will show signs of drooping leaves (wilting) then die if the lack of water is prolonged.
However, sometimes wilting or droopiness of the plant can be caused by other reasons such as the plant being top-heavy, too much moisture, pests, and diseases. Overwatering in aloe vera plants is in most cases the major cause of drooping leaves and not due to sunburn.
Can an aloe plant recover from sunburn?
An aloe can recover from sunburn if you move the plant to a shaded area and water it lightly. Remove the affected leaves and leave the healthy ones to acclimate. If the plant is in a pot, place it in a room that only receives bright indirect light.
Here are a few tips to help your sunburnt aloe recover faster:
 - Since the soil in the pot is dry, add just enough water to make it moist instead of making it too wet. Too much water can lead to root rot that can also kill the succulent.
 - Keep an eye on it for three to four days.
 - If the adjustments fail to revive the scorched aloe, move it to another room until you see positive changes.
For aloes planted in gardens, consider mounting a shade-like structure to it. For example, you can construct the shade using four wooden sticks and dried grass. Dip the sticks into the soil so that it forms a wall-like structure. Use three extra posts to support the dried grass. Now mount the dried grass on top of the four sticks.
Alternatively, you can uproot the plant and re-plant it in a pot using a fresh potting mix. Finally, place the pot in an area with shade.
How to Revive a Sunburnt Aloe Plant
Now that you've known the symptoms of a sunburnt aloe plant, it's time to revive it. The trick to save your aloe plant is to remove anything that increases its chances of wilting due to sunburn.
Here's how to revive a sunburnt aloe plant:
1. Move the pot away from direct sunlight
Assuming your aloe vera plant got sunburns because the pot was in a room allowing direct sunlight, simply move the pot somewhere with indirect sunlight. Ensure the new area receives as little sunlight as possible.
For example, move the plant from an east-facing window to a south facing window, or any window that receives few hours of indirect sunlight. With time, you should see some improvement.
2. Water the succulent to keep the root zone moist
A sunburnt aloe vera plant signifies thirst. That means you have to water it from the roots by placing it in a bowl of water. Leave it there for two to three days. On the third day, you should see the brown leaves turning green again.
From here, you can re-pot it and place it in a room receiving indirect sunlight.
3. Adjust the watering frequency with the seasons
If previously you were used to watering your aloe once a month, it would be best to readjust the watering pattern to two to three week to prevent aloe leaves from being sunburnt during summer.
Slightly increasing the amount of water will help revive the sunburn on your aloe vera plant as soon as the signs start to appear and also while they are still reversible.
4. Cut off the sunburnt leaves
Unfortunately, not all leaves will recover or fade into a tan no matter what you do. If your plant is burnt beyond measure, your only option is to cut off the damaged leaves.
But if they are showing signs of improvement, you can trim them. Use a sharp knife or clippers to avoid damaging the entire leaf structure.
How to prevent aloe plant from sunburn
It's important to note that aloe can survive harsh weather conditions, but that doesn't mean it's immune to the side effects of sunburns. Whether you are a beginner in planting aloes or a professional gardening enthusiast, learning how to prevent an aloe plant from sunburn can save you from heartaches in the future.
The secret is to allow your aloe vera to build up to stronger sun exposure slowly. Let it acclimate to different light settings than they are in.
Prevention of sunburns also involves getting your plant to harden off. This works by placing it outside for full shade for five to six days, then slowly introducing it to two to three hours of the morning sun.
Avoid the afternoon sun as much as you can then from there, increase your plant's sun exposure to over two to three weeks.
Suppose you notice your aloe is struggling with symptoms like browning or wilting away, then there might be other underlying causes other than sun scorch. If the leaves appear mushier and brown than before, your plant could be low on moisture because water should reach the tips last.
You're probably thinking of overwatering as a last resort when in the real sense, you could be doing more harm than good. Consider changing the soil and pot and repeat the process. If it still doesn't revive, it's time to start over with a new plant.
One of the perks that come with planting aloe vera is its resilient nature. It's the reason it grows even in the harshest conditions. However, no matter how tolerant your plant may be, learn from your mistakes. Your watering pattern should neither be obsessive or negligent. Only ensure the plant receives adequate water and sunlight so that you can reap the benefits of having it as a houseplant.
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