Sunday, April 28, 2013

Virtual Evolution

A research team at Cornell University has created a computer algorithm that simulates evolution. The goal of the creatures is to move as fast and efficiently as possible. The creatures produced by the algorithm worked much better than those designed by humans. This program demonstrates the processes of natural selection because the creatures that can move farther are used as the basis for the next generation of creatures.

NOS Themes:
1. science is based on evidence - the algorithm is based on "developmental biology"
2. role of chance - the creatures that preformed better were used to create new creatures
3. role of curiosity - this program demonstrates evolution that normally takes thousands of years in seconds

Article: http://www.sciencedaily.com/releases/2013/04/130423135843.htm
Video: http://www.youtube.com/watch?v=z9ptOeByLA4&feature=youtu.be
 An interesting program that is similar: http://boxcar2d.com/

Shorter-winged swallows evolve around highways

Article:  http://www.sciencenews.org/view/generic/id/349028/description/Shorter-winged_swallows_evolve_around_highways

A cliff swallow.

Researchers Charles and Mary Bomberger Brown have been studying cliff swallows since the 1980s.  Over the years, they have traveled to many swallow colonies built under bridges, trying to learn more about the birds' behavior.  They have made an interesting discovery:  since the start of their study, the number of swallows killed by cars has gradually gone down, with only four found in 2012.  The average length of the birds' wings has also been decreasing.  The data suggest that cliff swallows have adapted to living near highways.  Shorter wings may give them greater agility and allow them to take off more quickly, decreasing their chances of becoming roadkill.

NOS Themes:
  • Science is tentative. Before concluding that the cliff swallows were better at surviving due to their shorter wing spans, the researchers eliminated other possible causes such as smaller swallow populations or an increase in scavengers eating the roadkill.  They have not ruled out the possibility of other characteristics being selected for, such as more cautious swallows.
  • Science is observable.  The team was able to back their findings with quantitative data giving the numbers of swallows they found hit by cars each year.
  • Science is consistent.  The trend of declining numbers of dead birds has continued all this time.

Thursday, April 25, 2013

Plumage Color Speeds Up Evolution

Recently, researchers found new evidence to support a 60-year-old evolution theory. A study conducted by University of Melbourne scientists Dr Devi Stuart-Fox and Dr Andrew Hugall was published in the journal Nature. It described the investigation into the supposed link between multiple color variations within a species and faster evolution of that species.

This idea was first proposed in the 1950s by scientists such as Julian Huxley. However, this is the first study that has come out to support it. It confirms a major theory of evolutionary biology using the combined work of geneticists and birdwatchers worldwide.

Although this study focused specifically on birds, it was intended to support the theory applied broadly to polymorphism in other animals, such as fish, lizards, or insects. The researchers chose to study birds for purely practical purposes - there was already a wealth of information regarding bird coloration.

Specifically, the study used an accumulation of genetic codes to conclude that color polymorphic species tend to evolve at a faster rate into color monomorphic species. Existing species with different color forms are relatively young and rare.

Now that this has been observed and supported with evidence, the next step that the scientists intend to take is to test explanations for this phenomenon.

Photo Credit: Andreas Trepte (Wikimedia Commons)

NOS Themes:
  1. Science is collaborative - The article made sure the mention that the study required a group effort that was global in scale. It also described how the study built upon information and theories that had come before in order to reach its conclusions. 
  2. Science is based on evidence - Although the idea was proposed 60 years ago, it has not been considered fact until now, when there is enough evidence for it to be supported. 
  3. Science is subject to debate and tentative - Until now, this idea has been discussed and treated as fair game to either be confirmed or dismissed. Now that there is evidence, it becomes harder to deny but not impossible, as new evidence could come out to disprove it. 

Further Reading:

The Brain and its linkage to Alcohol

Researchers at the University of Texas at Austin and the Pasteur Institute in France collaborated with each other and managed to link alcohol with the brain. Researchers at the University of Texas had recently created a paper on the key enabler of alcohol's affects on the brain, but couldn't produce enough evidence to back up their claim due to the brain proteins inability to crystallize to enough of a degree to be analyzed by X-ray crystallography. Pasteur Institute researchers came up with an alternative. By using a bacteria which had a similar protein sequence with that of the brain protein used, the researchers were able to properly crystalize the bacteria. This is important because with further examination of this protein sequence, hopefully researchers will be able to produce a cure for alcoholics.

http://www.sciencedaily.com/releases/2013/04/130425132804.htm

NOS:
Science is Collaborative, the researchers worked together even though they were on different continents at the time.
Role of Chance, researchers at Pasteur Institute were lucky to have come across a bacteria with a similar protein sequence with that of brain protein's.
Science is based on Evidence, even though the researchers had published a paper on the key enabler's, they had no hard evidence because they weren't able to crystalize the the brain protein.    

Skulls Shed New Light On the Evolution of the Cat



http://www.sciencedaily.com/releases/2012/07/120711141010.htm
In this article scientists hypothesize the evolution of modern domestic cats and modern big cats like lions, tigers, and lynxes from prehistoric saber-toothed cats.  They found that modern ccats diverged from sabre toothed cats early on and then split again into modern domestic cats and big cats.  To back up their claims they studied the skulls of modern cats and preserved fossils of sabre toothed cats.  They took measurements of the teeth and skull parts and compared the specimens to each other.

NOS Themes:
*Science is collaborative.  The scientists in this article were building on different theories of feline evolution from before and hoping to gather evidence for it with a new approach.
*Role of chance.  The scientists were surprised at how much data they were able to collect and interpret just by simple measurements.
*Role of motivation and curiosity.  The scientists in this study were interested in feline evolution and thus motivated to study the three types of cats.

Humpback Whales are Learning from One Another

      Humpback whales off the coast of New England have been observed hunting prey in a peculiar way. Due to the shortage of herring, which started in 1980, whales were forced to find new prey, and also a new way to hunt.

       The whales now hunt by blowing bubbles underwater or slapping their tail on the surface of the water, creating bubble nets and effectively trapping the prey. This is called 'lobtail feeding'. In the past 30 years, nearly 40% of the population has learned about this neat trick. It has also been proven that whales can teach other their 'songs'.

        These observations about whales sharing and teaching information within the community lead scientists to believe that whales and dolphins have evolved sophisticated cultural capabilities.



Website:  http://www.sciencedaily.com/releases/2013/04/130425142353.htm

Themes of Nature of Science:
1. Science is based on evidence
2. Role of motivation and curiosity


Galapagos Corals May Predict the Future of Reefs Worldwide

Galapagos Corals May Predict the Future of Reefs Worldwide

Galapagos coral
Although the corals around the Galapagos Islands are quite scarce, researchers have discovered them and have been using them to direct their research on how coral growth will be affected in the future. A team of researchers with the Khaled bin Sultan Living Oceans Foundation’s Global Reef Expedition, a six-year survey of coral reefs worldwide, spent 18 days aboard the Golden Shadow research vessel in the Galapagos, surveying the corals of eight islands. Along with fascination from the beauty of the Islands, they were able to discover that the amount of CO2 in the water also plays a giant role on coral growth, as well as the temperature changes of the water and the seasons. Derek Manzello, a team member, learns that CO2 conducts a negative effect on coral reefs. CO2 creates acid in the water, and highly acidic water leads to the poor growth of coral reefs. High acidic waters or waters of a very high temperature, cause the symbiotic algae on the reefs to fade creating great damage to the coral reefs. So why does any of this really matter? Well, the answer is simple : You may already know that many organisms in the water rely on coral reefs for shelter or food, but they're also involved in assisting with the reproduction process of an organism. Some organisms, like the  Porites lobata, actually release sperm or egg into the water, which then travels to create new coral. Coral reefs have been valuable to our environment for ages. Up till now, scientists believed that coral reefs were tangled in dangerous situations, now they are beginning to uncover the news that there may be a chance for recovery.




 Link to the Article:

http://ens-newswire.com/2012/11/20/galapagos-coral-may-predict-the-future-of-reefs-worldwide/ 

NOS Themes:

1. Science is collaborative
2. Science is experimental
3. Science is based on evidence 

Primates' Vocal Lip Smacks Resemble Human Speech?



Picture Source:
http://www.redorbit.com/media/uploads/2013/04/gelada-baboon-shutterstock_58545874-617x416.jpg

Article Link:
http://www.biologynews.net/archives/2013/04/08/rare_primates_vocal_lipsmacks_share_features_of_human_speech.html

Geladas, a rare primate species, only live in the remote mountains of Ethiopia. This species has a rare call that closely resembles human speech. The behavior of lip smacking, present among many primates, hints at an evolutionary step towards human speech. Most primates who display this behavior lack syllables and rapid fluctuation in pitch that are present in human speech. Thore Bergman of the University of Michigan in Ann Arbor first began his research on Geladas in 2006. He states, "I would find myself frequently looking over my shoulder to see who was talking to me, but it was just the geladas" (article). He has now analyzed recordings of their lip smacking to identify similarities with human speech. The rhythm in both lip smacking and human speech corresponds with the actions of opening and closing the mouth.

I believe that the hints from the gelada species are a good indication that evolution helped develop the human body structure and our abilities. This topic really relates to what we are learning about right now, that each species has their own set of rituals and behaviors that shape how they evolve and how their later generations will behave. The sounds made by the geladas may just be coincidental, although resemblance of human speech is absolutely amazing coming from another species. 

NOS Themes:
  • Role of motivation and curiosity- Bergman was interested in the topic and began to research it because of that.
  • Role of chance- it is possible that it is just a coincidence that the geladas sound like human speech, and not actually a hint at evolution.
  • Person's view and experience can influence data- Bergman alone can be partially influenced by his want to have the gelada species speech resemble human speech.


Scientists Create Phantom Sensations in Non-Amputees

Summary:
File:Belgrade hand.JPG
Belgrade Hand

Neuroscientists at the Karolinska Institute in Sweden have suggested that is it possible to evoke the feeling of having a phantom limb on a healthy, normal person. Experiencing a phantom limb is a vivid sensation that the missing limb is still present. It is like imagining a body part that you do not have, or have lost. The elaborate study includes eleven different experiments and over two-hundred volunteers. The way for scientist to prove that non-amputees can experience a phantom limb is to hide the limb from the volunteers sight and to do something, like tickling, to their real limb, while also doing the same thing in the clear sight of the person. In less than a minute, the participant's brain transferred the sensation of touch, on their real limb, to the region of empty space, their phantom limb. The brain is an amazing organ, and the researchers are hoping their results will offer insight into future research on phantom pain in amputees.

NOS Themes:
  • Science is collaborative- many scientists have been working on this.
  • Science is base on evidence- the neuroscientists have collected tons of data.
  • Person's view and experience can influence data- everyone's brain is different, so they might perceive the sense of touch differently.
  • Conflicts within the scientific community- there are many people in the world that are amputees.
  • Role of motivation and curiosity- many people are very curious to see if the experience of having a phantom limb can be replicated.
Article Link: Biologynews.net

Explaining the Bio-toxin Ricin

Ricin is a poison that comes from the seeds of the castor plant. In the past, malicious groups have sent envelopes of this toxin along with letters to attack their targets. Recently, the United States Postal Service has intercepted 2 letters laced with ricin addressed to Senator Roger Wicker  and President Barack Obama. Also in 2011, four Americans were arrested on accounts that they were planning to poison many with ricin and destroy key government buildings. It is know that ricin is deadly, but how does it work?

Proteins are the building blocks of the human body; coded for by our RNA and created by the ribosomes, these key elements  help to transport many important nutrients, regulate systems, as well as create blood. Ricin interrupts the synthesis of proteins
 by binding to the ribosomes and breaking them open. This results in adverse effects such as organ failure. Even though risin can severely damage the body, it needs to be ingested or injected to cause immediate and dangerous symptoms. Thankfully, the risin sent by letter probably would not have accomplished the sender's goals even if it had reached the oval office. Dan Brown, a nutritional toxicologist at Cornell University says that, "the letter openers would have had to place their faces almost directly into the envelopes while opening them to experience negative effects." This is because the chemical needs to enter the bloodstream in order interrupt ribosome function. 

This article demonstrates themes of science because:
 ~Science is collaborative. Brown worked with many other scientists to understand risin.
~Science is based on evidence. Researchers studied those exposed to risin as well as performing experiments on mice to determine the molecular effects of the poison.  

Article link: http://www.scientificamerican.com/article.cfm?id=murderous-mail-how-dangerous-ricin-attacks

Mysterious Hot Spots in Cool Red Supergiant


Mysterious Hot Spots in Cool Red Supergiant

        
  Scientists have recently discovered, via a radio telescope, e-MERLIN, mysterious hot spots on the cool red supergiant star, Betelgeuse. Betelgeuse is the nearest red supergiant to earth, and it is estimated to be 1000 times larger than our sun. It is 650 light years away from earth, but through new telescoping capabilities, scientists recently released a photo of the star, revealing hot spots surrounding the sun. Although no one knows exactly why these hot spots are there or how they are so hot, Dr. Anita Richards guessed, "One possibility is that shock waves, caused either by the star pulsating or by convection in its outer layers, are compressing and heating the gas. Another is that the outer atmosphere is patchy and we are seeing through to hotter regions within. The arc of cool gas is thought to be the result of a period of increased mass loss from the star at some point in the last century but its relationship to structures like the hot spots, which lie much closer in, within the star's outer atmosphere, is unknown."

NoS Themes
-Science is based on evidence
-Role of motivation and curiosity

 http://www.sciencedaily.com/releases/2013/04/130424222432.htm

Sam Pahl
Hour 1

Endangered Deer Making a Notable Comeback

The Huemal Deer Lives in a region known as Patagonia in South America. Since the early 19th century the population of this naturally tame and docile iconic Chilean figure has dropped almost 99%. This is mostly because of overhunting and the deer's competition for its natural habitat with cattle ranching. Within the last 9 years or so the population has made a dramatic recovery from it's endangered status. It has also been able to move down out of the mountains where it took refuge from hunters and ranching, and back into its natural forested habitat in which it thrives. If it had not been to a group of dedicated park rangers and a team of scientists the deer may be facing extinction. For a very long time the area in which the Huemal lives has been a nation park, but only recently has it been patrolled by government officials to enforce environmental regulations there (i.e. no hunting). The scattered stations are positioned around the wide expanse of unpopulated land, in fact, It can take up to two days by river to reach one of the park ranger stations. With luck and persistence, the Chilean government can sustain their efforts to monitor the parks and enforce conservation. Things look to be getting much better for the Huemal, as well as hundreds of other species living in the land. 
(Huemal Deer lives in the blue range)

Bedbugs Raise Their Defences

Link: http://www.sciencenews.org/view/generic/id/348961/description/News_in_Brief_Bedbugs_raise_genetic_defense_against_pesticides

download

In a recent study done at the University of Kentucky, scientists looked to see how bedbugs were escaping death from a common pesticide.  Researchers collected 21 groups of these bedbugs from around the country and used the pesticide on the groups of bedbugs to see how they were not dying from it.  They found that the bedbugs could turn on diverse genes on their outer covering, and the genes would help to keep the pesticide out, and they would also help to pump the pesticides away from the bedbug's nerve cells.  Scientists have not found any other insect that uses this kind of defense against pesticides.
NOS Themes:
  • Science is Collaborative: The researchers worked together to figure out how the bedbug was escaping unharmed from the pesticides.
  • Science is Based on Evidence: The researchers collected many samples to be sure that this is the defense that the bedbugs were using.
  • Role of Motivation and Curiosity: The scientists must have been curious once they decided to conduct this experiment.
Mitchell Gardner Hour:2

Monkeys Conform to Social Norms

http://www.sciencedaily.com/releases/2013/04/130425142351.htm

A new study done on monkeys show that they will conform to the social norms of another group. A group of researchers at the University of St. Andrews performed tests on monkeys where they would dye corn two different colors and make one of the colors taste repulsive. The two different groups of monkeys would have the opposite colors tasting bad. Once the monkeys had figured out that only one color tasted good, the scientists mixed the two groups and gave them both colors of corn. The group that moved instantly accepted that because their hosts were eating the "bad" corn, they should eat it too. This behavior surprised the scientists and showed them that monkeys can be as socially intelligent as humans.

NOS Themes
Role of Skepticism
Role of motivation and curiosity




Alex Olawsky
Hr 3

"Melting" Away the Fat.

     We all dream about having the flattest bellys or the best six pack but these are not easy things to maintain. Or are they? Scientists believe they are getting the closer to being able to convert white fat cells (the bad stuff) to brown fat cells (the heat makers). They look at rats closely because rats are believed to be able to control their fat burning. This may turn out to not work in humans like it does in rats so until then I guess we are stuck working out and eating healthy.

Here is a link to the cite so you can read more
http://www.biologynews.net/archives/2013/04/23/love_handles_melt_away_at_the_push_of_a_button.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+biologynews%2Fheadlines+%28Biology+News+Net%29



NOS Themes

Role of motivation and curiosity
Role of skeptiscism
Role of credibility

Something's Fishy in the Tree of Life


Something's Fishy in the Tree of Life

This article is about a recent study published by researchers at the university of Oklahoma. The study provides new insight on relationships and the evolution of fish species. The researchers used genetic data and physical characteristics to organize species of fish into a "tree of life". This extensive DNA analysis is the most complete study of the evolution of fish ever. The study both supported previous hypotheses about fish relationships as well as showed new groupings of species. The article gives the example of the streamlined tuna and marlin, who were once thought to be closely related. It appears that tuna are actually more related to seahorses, and marlins to flatfish. This new information could be helpful to disease research and climate change research, now that scientists know which species of fish are actually more closely related.

NOS Themes:

  • Science is collaborative
  • Science is based on evidence
  • Role of motivation and curiosity

Article found here

Dinosaur Egg supports Evolutionary Link Between Birds And Dinosaurs

This article is about a recent discovery that a dinosaur called Troodon laid their eggs almost vertically, resulting in only the egg bottoms to be buried in mud. Based on the researchers calculations, the eggshells were very similar to those of brooding birds, which indicates that the eggs weren't completely buried in nesting material. Both the eggs and the surrounding sediments left on the eggs support partial burial, and thus an adult dinosaur would have covered the exposed eggs during incubation. While the nesting style for the Troodon is strange, there are similarities with a bird called the Egyptian Plover. Another factor of evidence is the number of pores in the eggshell that allow respiration, and the lesser number support the fact that the egg was exposed to the open air. This particular study helps substantiate that bird like nesting behavior patterns evolved from the meat eating dinosaurs, and it evolved prior to the origin of birds. This adds to a growing collection of evidence that shows a close connection between birds and dinosaurs.


NOS themes:
Science is based on evidence
Role of credibility
Role of skepticism

http://current.biologyguild.com/birds-and-dinosaurs/

Nic McKenney, Hour 1

Humpback Whales Learn Hunting Technique From Peers


For a long time, we have believed that developing new skills through learning from peers was a uniquely human characteristic. Recently, however, marine biologists have made a very interesting discovery about the behavior of humpback whales off the coast of Maine. For 27 years teams have been observing the hunting techniques of the whales. Since then, a new trend has become more and more popular. Believed to have originated from one resourceful whale and spread throughout the population, this technique is something the biologists have only recently begun to see. This method involves the whale slapping the surface of the water four times with his tail, and proceeding to dive underneath, feeding off the schools of sand lance fish that have been organized by the tail-pounds. After performing statistical analysis, the biologists have concluded that the humpback whales were a million times more likely to have learned this technique from their peers, rather than  each developing it on their own. This discovery will hopefully help biologists discover other instances of collective animal-teaching like this.

NOS Themes
  • Science is collaborative
  • Science is based off evidence
  • Role of motivation and curiosity

Controling Cardiovascular Disease



Atherosclerosis is the leading cause of death in most Western countries. Another work for Cardiovascular Disease, Atherosclerosis occurs when inflammatory compounds such as nuclear factor-B (NF-ĸB) allow fatty plaque to stick to artery walls, eventually causing stroke or heart attack. An international team of scientists from Spain, the United States, England, and Germany studied the anti-inflamatory effects of an NLS Peptide, which is a protein specifically coded to fight the inflamatory effects of NF-kB. So far, treatment of Cardiovascular disease using the NLS peptide have greatly reduced plaque build-up in the cardiovascular systems of mice. Even better, the treatment has been succesful both in the early stage (if the disease was discovered early in the patient) and in late stages of plaque development. Although NF-kB only inflames the artery, as lead investigator Carmen Gomez-Guerrero said, "[NF-kB effects] early phases characterized by lipid modification, chemotaxis, adhesion of leukocytes, monocyte differentiation, foam cell formation, and inflammatory cytokine expression [all the way] to more advanced lesions involving cell death, migration and proliferation of VSMCs, and fibrous cap formation." The good news is, this new protein looks like it can neutrilize the threat that NF-kB poses.

NOS themes:
-Collaboration: Scientists from all over the world collaborated on this study
-Motivation: Cardiovascular disease is a dangerous ailment that kills thousands of people every year

http://www.biologynews.net/archives/2013/04/17/cellpermeable_peptide_shows_promise_for_controlling_cardiovascular_disease.html

New Immune Cells Hint at the Cause of Eczema

A new type of immune cell designated to fighting off parasitic invaders has been discovered by researchers from the Immune Imaging and T cell Laboratories at the Centenary Institute. The cell is a part of a family of cells known as the innate lymphoid cells. This family was discovered a little under five years ago and only found in the gut and lungs. This new cell, however, has been found in quite large numbers in the skin. This cells show what could be a link to allergic skin diseases. After testing, the cells were discovered to be able, when stimulated,to spread quickly and cause an inflammatory skin disease known as Eczema.
 
 ^^^^This is a false color image of the skin showing the newly discovered immune cells, which have shown a potential link to allergic skin diseases like eczema.

Source: http://www.biologynews.net/archives/2013/04/22/new_immune_cells_hint_at_eczema_cause.html

Exotic cat found to have lived in the UK

In the article that I read it talked about an exotic cat that was found in England and was stuffed, and put in a museum in England. When scientists were able to analyze it they found that it was actually a Canada Lynx, and it was the earliest evidence they had found of an escaped exotic cat in England. The lynx was actually shot in the early 1900's and was donated to a museum where it was thought that it was a Eurasian lynx. Scientists thought that the animal was one of 4 modern lynx species, and using it's color, leg length, and markings, it was determined that it is a Canadian lynx. Lynx's hadn't been found in England since the 9th century, but now there is a record of at least one being there.

Photo: A lynx in Canada’s Yukon Territory

Link: http://www.livescience.com/29008-exotic-cat-prowled-british-countryside.html

NOS Themes: Science is collaborative - Many scientists analyzed this cat to be able to determine what type of lynx it was.
Science is based on evidence - The scientists used different characteristics of the lynx to be able to see what it really was.
Science is subject to debate - There was a 99.9% chance that the lynx is Canadian, but you could argue that it could be part of the 0.1%, and that its not actually a Canadian lynx.

A New and Easy Way to Burn Loose Extra Weight?

There are different kinds of fat cells including white fat cells and brown fat cells. Excess weight comes from white fat cells which store extra food, but brown fat cells burn the extra energy, resulting in losing more weight. Now, Professor Dr. Alexander Pfeifer and other scientists working with him are developing new ways of turning the white cells into brown cells. They discovered a way to "switch" microRNA in mice to turn the white cells into brown cells. MicroRNA is very important because it controls gene activity. The specific gene if microRNA 155 that controls brown fat function (biology news). When microRNA is controlling the production of brown white cells, it is limiting the amount being made, but they found a way to to make the transcription produce brown fat faster to make themice burn fat quicker. When the proportions are off, the cell will read it, and they will keep making more brown fat cells. The scientists are now looking toward the future, and they want to start developing drugs to lower the obesity rate. They are confident that it will work in humans, just as it did with the mice, but it will be a while until they develop a suitable drugs.

NOS Themes:
Role of motivation and curiosity because scientists want to combat obesity by trying to make it easer to lose weight.
Science is collaborative because Pfeifer and other scientists are working together to solve the problem.

http://www.biologynews.net/archives/2013/04/23/love_handles_melt_away_at_the_push_of_a_button.html

Trees Role in Smog Production

After years of hard working, researchers at the University of North Carolina discovered precisely how trees play a role in air pollution. Trees produce and emit isoprene, a molecule which helps protect the leaves from oxygen damage. But, earlier in 2004, researchers found that isoprene was likely involved in the production of tiny matter which can get lodged on to your lungs and lead to asthma of lung cancer. It can also cause harm to other tissues along with the environment! The study that was conducted found that when isoprene was exposed to the sun, it reacts with human made nitrogen-oxides to create particulate matter. Isoprene's original intentions was to  protect trees, but since it became present with nitrogen oxide, it has started to become a negative effect on health and the environment

NOS Themes:

  • Role of motivation and curiosity 
  • Science is based on evidence
  • Science is collaborative 

Link to the article: 

Jack Nermyr