What Is a Coma?

Coma is a state of unconsciousness in which a person cannot be awakened; fails to respond normally to painful stimuli, light, or sound; lacks a normal wake-sleep cycle; and does not initiate voluntary actions. A person in a state of coma is described as being comatose. A distinction is made in the medical community between a real coma and a medically induced coma, the former is a result of circumstances beyond the control of the medical community, while the latter is a means by which medical professionals may allow a patient's injuries to heal in a controlled environment.

A comatose person exhibits a complete absence of wakefulness and is unable to consciously feel, speak, hear, or move. For a patient to maintain consciousness, two important neurological components must function. The first is the cerebral cortex—the gray matter that forms the outer layer of the brain. The other is a structure located in the brainstem, called reticular activating system (RAS).

Injury to either or both of these components is sufficient to cause a patient to experience a coma. The cerebral cortex is a group of tight, dense, "gray matter" composed of the nuclei of the neurons whose axons then form the "white matter," and is responsible for perception, relay of the sensory input via the thalamic pathway, and many other neurological functions, including complex thinking.

RAS, on the other hand, is a more primitive structure in the brainstem which includes the reticular formation (RF). The RAS area of the brain has two tracts, the ascending and descending tract. Made up of a system of acetylcholine-producing neurons, the ascending track, or ascending reticular activating system (ARAS), works to arouse and wake up the brain, from the RF, through the thalamus, and then finally to the cerebral cortex. A failure in ARAS functioning may then lead to a coma. The word is from the Greek κῶμα koma, meaning "deep sleep.”

Signs and Symptoms of a Coma

Generally, a person who is unable to voluntarily open the eyes, does not have a sleep-wake cycle, is unresponsive in spite of strong tactile (painful) or verbal stimuli, and who generally scores between 3 and 8 on the Glasgow Coma Scale is considered in a coma. Coma may have developed in humans as a response to injury to allow the body to pause bodily actions and heal the most immediate injuries before waking. It therefore could be a compensatory state in which the body's expenditure of energy is not superfluous. The severity and mode of onset of coma depends on the underlying cause. For instance, severe hypoglycemia (low blood sugar) or hypercapnia (increased carbon dioxide levels in the blood) initially cause mild agitation and confusion, but progress to obtundation, stupor, and finally, complete unconsciousness. In contrast, coma resulting from a severe traumatic brain injury or subarachnoid hemorrhage can be instantaneous. The mode of onset may therefore be indicative of the underlying cause.

Causes of a Coma

Coma may result from a variety of conditions, including intoxication (such as drug abuse, overdose or misuse of over the counter medications, prescribed medication, or controlled substances), metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as strokes or herniations, hypoxia, hypothermia, hypoglycemia, eclampsia or traumatic injuries such as head trauma caused by falls, drowning accidents, or vehicle collisions. It may also be deliberately induced by pharmaceutical agents during major neurosurgery, to preserve higher brain functions following brain trauma, or to save the patient from extreme pain during healing of injuries or diseases.

Forty percent of comatose states result from drug poisoning. Drugs damage or weaken the synaptic functioning in the ARAS and keep the system from properly functioning to arouse the brain. Secondary effects of drugs, which include abnormal heart rate and blood pressure, as well as abnormal breathing and sweating, may also indirectly harm the functioning of the ARAS and lead to a coma. Seizures and hallucinations have shown to also play a major role in ARAS malfunction. Given that drug poisoning is the cause for a large portion of patients in a coma, hospitals first test all comatose patients by observing pupil size and eye movement, through the vestibular-ocular reflex.

The second most common cause of coma, which makes up about 25% of comatose patients, occurs from lack of oxygen, generally resulting from cardiac arrest. The Central Nervous System (CNS) requires a great deal of oxygen for its neurons. Oxygen deprivation in the brain, also known as hypoxia, causes neuronal extracellular sodium and calcium to decrease and intracellular calcium to increase, which harms neuron communication. Lack of oxygen in the brain also causes ATP exhaustion and cellular breakdown from cytoskeleton damage and nitric oxide production.

Twenty percent of comatose states result from the side effects of a stroke. During a stroke, blood flow to part of the brain is restricted or blocked. An ischemic stroke, brain hemorrhage, or tumor may cause such cessation of blood flow. Lack of blood to cells in the brain prevents oxygen from getting to the neurons, and consequently causes cells to become disrupted and eventually die. As brain cells die, brain tissue continues to deteriorate, which may affect functioning of the ARAS.

The remaining 15% of comatose cases result from trauma, excessive blood loss, malnutrition, hypothermia, hyperthermia, abnormal glucose levels, and many other biological disorders.

Prognosis

Comas can last from several days to several weeks. In more severe cases a coma may last for over five weeks, while some have lasted as long as several years. After this time, some patients gradually come out of the coma, some progress to a vegetative state, and others die. Some patients who have entered a vegetative state go on to regain a degree of awareness. Others remain in a vegetative state for years or even decades (the longest recorded period being 42 years).

The outcome for coma and vegetative state depends on the cause, location, severity and extent of neurological damage. A deeper coma alone does not necessarily mean a slimmer chance of recovery, because some people in deep coma recover well while others in a so-called milder coma sometimes fail to improve.

People may emerge from a coma with a combination of physical, intellectual, and psychological difficulties that need special attention. Recovery usually occurs gradually—patients acquire more and more ability to respond. Some patients never progress beyond very basic responses, but many recover full awareness. Regaining consciousness is not instant: in the first days, patients are only awake for a few minutes, and duration of time awake gradually increases. This is unlike the situation in many movies where people who awake from comas are instantly able to continue their normal lives. In reality, the coma patient awakes sometimes in a profound state of confusion, not knowing how they got there and sometimes suffering from dysarthria, the inability to articulate any speech, and with many other disabilities.

Predicted chances of recovery are variable owing to different techniques used to measure the extent of neurological damage. All the predictions are based on statistical rates with some level of chance for recovery present: a person with a low chance of recovery may still awaken. Time is the best general predictor of a chance of recovery: after four months of coma caused by brain damage, the chance of partial recovery is less than 15%, and the chance of full recovery is very low.

The most common cause of death for a person in a vegetative state is secondary infection such as pneumonia, which can occur in patients who lie still for extended periods.

There are reports of patients coming out of coma after long periods of time. After 19 years in a minimally conscious state, Terry Wallis spontaneously began speaking and regained awareness of his surroundings.

A brain-damaged man, trapped in a coma-like state for six years, was brought back to consciousness in 2003 by doctors who planted electrodes deep inside his brain. The method, called deep brain stimulation (DBS) successfully roused communication, complex movement and eating ability in the 38-year-old American man who suffered a traumatic brain injury. His injuries left him in a minimally conscious state (MCS), a condition akin to a coma but characterized by occasional, but brief, evidence of environmental and self-awareness that coma patients lack.

Comas lasting seconds to minutes result in post-traumatic amnesia (PTA) that lasts hours to days; recovery plateau occurs over days to weeks. Comas that last hours to days result in PTA lasting days to weeks; recovery plateau occurs over months. Comas lasting weeks result in PTA that lasts months; recovery plateau occurs over months to years.

                                            https://en.wikipedia.org/wiki/Coma

Nearest Star Emits Deathly Flare

Powerful Flare from Star Proxima Centauri Detected with ALMA
Puts habitability of nearby system into question

National Radio Astronomy Observatory – February 26, 2018 -- Space weather emitted by Proxima Centauri, the star closest to our sun, may make that system rather inhospitable to life after all.

Using data from the Atacama Large Millimeter/submillimeter Array (ALMA), a team of astronomers discovered that a powerful stellar flare erupted from Proxima Centauri last March. This finding, published in the Astrophysical Journal Letters, raises questions about the habitability of our solar system’s nearest exoplanetary neighbor, Proxima b, which orbits Proxima Centauri.

At its peak, the newly recognized flare was 10 times brighter than our sun’s largest flares, when observed at similar wavelengths. Stellar flares have not been well studied at the millimeter and submillimeter wavelengths detected by ALMA, especially around stars of Proxima Centauri’s type, called M dwarfs, which are the most common in our galaxy.

“March 24, 2017, was no ordinary day for Proxima Cen,” said Meredith MacGregor, an astronomer at the Carnegie Institution for Science, Department of Terrestrial Magnetism in Washington, D.C., who led the research with fellow Carnegie astronomer Alycia Weinberger. Along with colleagues from the Harvard-Smithsonian Center for Astrophysics, David Wilner and Adam Kowalski, and Steven Cranmer of the University of Colorado Boulder — they discovered the enormous flare when they reanalyzed ALMA observations taken last year.

The flare increased Proxima Centauri’s brightness by 1,000 times over 10 seconds. This was preceded by a smaller flare; taken together, the whole event lasted fewer than two minutes of the 10 hours that ALMA observed the star between January and March of last year.

Stellar flares happen when a shift in the star’s magnetic field accelerates electrons to speeds approaching that of light. The accelerated electrons interact with the highly charged plasma that makes up most of the star, causing an eruption that produces emission across the entire electromagnetic spectrum.

“It’s likely that Proxima b was blasted by high energy radiation during this flare,” MacGregor explained, adding that it was already known that Proxima Centauri experienced regular, although smaller, X-ray flares. “Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water.”

An earlier paper that also used the same ALMA data interpreted its average brightness, which included the light output of both the star and the flare together, as being caused by multiple disks of dust encircling Proxima Centauri, not unlike our own solar system’s asteroid and Kuiper belts.

But when MacGregor, Weinberger, and their team looked at the ALMA data as a function of observing time, instead of averaging it all together, they were able to see the transient explosion of radiation emitted from Proxima Centauri for what it truly was.

“There is now no reason to think that there is a substantial amount of dust around Proxima Cen,” Weinberger said. “Nor is there any information yet that indicates the star has a rich planetary system like ours.”

The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

https://public.nrao.edu/news/2018-alma-flare-proxima/

Coming: Solid State Lithium Batteries

Charging Ahead to Higher Energy Batteries
Summary: Researchers have developed a new way to improve lithium ion battery efficiency. Through the growth of a cubic crystal layer, the scientists have created a thin and dense connecting layer between the electrodes of the battery.

Shinshu University, February 23, 2018 -- Professor Nobuyuki Zettsu from the Center for Energy and Environmental Science in the Department of Materials Chemistry of Shinshu University in Japan and the director of the center, Professor Katsuya Teshima, led the research.

The authors published their results online in January this year in Scientific Reports.

"Owing to some intrinsic characteristics of liquid electrolytes, such as low lithium transport number, complex reaction at the solid/liquid interface, and thermal instability, it has not been possible to simultaneously achieve high energy and power in any of the current electrochemical devices," said Nobuyuki Zettsu, as first author on the paper.

Lithium ion batteries are rechargeable and power such devices as cell phones, laptops, power tools, and even store power for the electrical grid. They're particularly sensitive to temperature fluxes, and have been known to cause fires or even explosions. In response to the problems with liquid electrolytes, scientists are working toward developing a better all-solid-state battery without liquid.

"Despite the expected advantages of all-solid-state batteries, their power characteristic and energy densities must be improved to allow their application in such technologies as long-range electric vehicles," Zettsu said. "The low rate capabilities and low energy densities of the all-solid-state batteries are partly due to a lack of suitable solid-solid heterogeneous interface formation technologies that exhibit high iconic conductivity comparable to liquid electrolyte systems."

Zettsu and his team grew garnet-type oxide solid electrolyte crystals in molten LiOH used as a solvent (flux) on a substrate that bonded the electrode into a solid state as they grew. A specific crystal compound known to grow cubically allowed the researchers to control the thickness and connection area within the layer, which acts as a ceramic separator.

"Electron microscopy observations revealed that the surface is densely covered with well-defined polyhedral crystals. Each crystal is connected to neighboring ones," wrote Zettsu.

Zettsu also said that the newly grown crystal layer could be the ideal ceramic separator when stacking the electrolyte layer on the electrode layer.

"We believe that our approach having robustness against side reactions at the interface could possibly lead to the production of ideal ceramic separators with a thin and dense interface," wrote Zettsu, noting that the ceramics used in this particular experiment were too thick to be used in solid batteries. "However, as long as the electrode layer can be made as thin as 100 microns, the stacking layer will operate as a solid battery."

One hundred microns is about the width of a human hair, and slightly less than twice the thickness of a standard electrode layer in contemporary lithium-ion batteries.

"All-solid-state batteries are promising candidates for energy storage devices," Zettsu said, noting that several collaborations between researchers and private companies are already underway with the ultimate goal of displaying all-solid-state battery samples at the 2020 Olympic games in Tokyo.

Zettsu and other researchers plan to fabricate prototype cells for electric vehicle use and for wearable devices by 2022.

Other collaborators on this project include researchers from the Institute for Materials Research at Tohoku University, Frontier Research Institute for Materials Science at Nagoya Institute of Technology, and the National Institute for Materials Science.

https://www.sciencedaily.com/releases/2018/02/180223151901.htm

Watson-Watt Invents RADAR

Sir Robert Alexander Watson-Watt, KCB, FRS, FRAeS (13 April 1892 – 5 December 1973) was a Scottish pioneer of radio direction finding and radar technology.

Watt began his career in radio physics with a job at the Met Office, where he began looking for ways to accurately track thunderstorms using the radio signals given off by lightning. This led to the 1920s development of a system later known as huff-duff. Although well publicized at the time, the system's enormous military potential was not developed until the late 1930s. Huff-duff allowed operators to determine the location of an enemy radio in seconds and it became a major part of the network of systems that helped defeat the U-boat threat. It is estimated that huff-duff was used in about a quarter of all attacks on U-boats.

In 1935 Watt was asked to comment on reports of a German death ray based on radio. Watt and his assistant Arnold Frederic Wilkins quickly determined it was not possible, but Wilkins suggested using radio signals to locate aircraft at long distances. This led to a February 1935 demonstration where signals from a BBC short-wave transmitter were bounced off a Handley Page Heyford aircraft. Watt led the development of a practical version of this device, which entered service in 1938 under the code name Chain Home. This system provided the vital advance information that helped the Royal Air Force win the Battle of Britain.

                                                               Robert Watson-Watt

After the success of his invention, Watson-Watt was sent to the US in 1941 to advise on air defence after Japan’s attack on Pearl Harbor. He returned and continued to lead radar development for the War Ministry and Ministry of Supply. He was elected a Fellow of the Royal Society in 1941, was given a knighthood in 1942 and was awarded the US Medal for Merit in 1946.

RADAR: The Air Defense Problem

During the First World War, the Germans had used Zeppelins as long-range bombers over London and other cities and defences had struggled to counter the threat. Since that time aircraft capabilities had improved considerably and the prospect of widespread aerial bombardment of civilian areas was causing the government anxiety. Heavy bombers were now able to approach at altitudes that anti-aircraft guns of the day were unable to reach. With enemy airfields across the English Channel potentially only 20 minutes’ flying-time away, bombers would have dropped their bombs and be returning to base before any intercepting fighters could get to altitude. The only answer seemed to be to have standing patrols of fighters in the air at all times but, with the limited cruising time of a fighter, this would require a huge air force. An alternative solution was urgently needed and in 1934, the Air Ministry set up a committee, the CSSAD (Committee for the Scientific Survey of Air Defence), chaired by Sir Henry Tizard to find ways to improve air defence in the UK.

Nazi Germany was rumoured to have a "death ray" using radio waves that was capable of destroying towns, cities and people. In January 1935, Harry Wimperis, Director of Scientific Research at the Air Ministry, asked Watson-Watt about the possibility of building their version of a death-ray, specifically to be used against aircraft. Watson-Watt quickly returned a calculation carried out by his young colleague, Arnold Wilkins, showing that the device was impossible to construct, and fears of a Nazi version soon vanished. However, he also mentioned in the same report a suggestion that was originally made to him by Wilkins, who had recently heard of aircraft disturbing shortwave communications, that radio waves may be capable of detecting aircraft: "Meanwhile attention is being turned to the still difficult, but less unpromising, problem of radio detection and numerical considerations on the method of detection by reflected radio waves will be submitted when required." Wilkins's idea, checked by Watt, was promptly presented by Tizard to the CSSAD on 28 January.

RADAR: Aircraft Detection and Location

On 12 February 1935, Watson-Watt sent the secret memo of the proposed system to the Air Ministry, Detection and location of aircraft by radio methods. Although not as exciting as a death-ray, the concept clearly had potential but the Air Ministry, before giving funding, asked for a demonstration proving that radio waves could be reflected by an aircraft. This was ready by 26 February and consisted of two receiving antennas located about 6 miles (9.7 km) away from one of the BBC's shortwave broadcast stations at Daventry. The two antennas were phased such that signals travelling directly from the station cancelled themselves out, but signals arriving from other angles were admitted, thereby deflecting the trace on a CRT indicator (passive radar). Such was the secrecy of this test that only three people witnessed it: Watson-Watt, his colleague Arnold Wilkins, and a single member of the committee, A. P. Rowe. The demonstration was a success; on several occasions a clear signal was seen from a Handley Page Heyford bomber being flown around the site. Most importantly, the Prime Minister, Stanley Baldwin, was kept quietly informed of radar's progress. On 2 April 1935, Watson-Watt received a patent on a radio device for detecting and locating an aircraft.

In mid-May 1935, Wilkins left the Radio Research Station with a small party, including Edward George Bowen, to start further research at Orford Ness, an isolated peninsula on the Suffolk coast of the North Sea. By June they were detecting aircraft at a distance of 16 miles (26 km), which was enough for scientists and engineers to stop all work on competing sound-based detection systems. By the end of the year the range was up to 60 miles (97 km), at which point plans were made in December to set up five stations covering the approaches to London.

One of these stations was to be located on the coast near Orford Ness, and Bawdsey Manor was selected to become the main centre for all radar research. In an effort to put a radar defence in place as quickly as possible, Watson-Watt and his team created devices using existing available components, rather than creating new components for the project, and the team did not take additional time to refine and improve the devices. So long as the prototype radars were in workable condition they were put into production. They soon conducted "full scale" tests of a fixed radar radio tower system that would soon be known as Chain Home, an early detection system that attempted to detect an incoming bomber by radio signals. The tests were a complete failure, with the fighter only seeing the bomber after it had passed its target. The problem was not the radar, but the flow of information from trackers from the Observer Corps to the fighters, which took many steps and was very slow. Henry Tizard with Patrick Blackett and Hugh Dowding immediately set to work on this problem, designing a 'command and control air defence reporting system' with several layers of reporting that were eventually sent to a single large room for mapping. Observers watching the maps would then tell the fighter groups what to do via direct communications.

By 1937 the first three stations were ready, and the associated system was put to the test. The results were encouraging, and an immediate order by the government to commission an additional 17 stations was given, resulting in a chain of fixed radar towers along the east and south coast of England. By the start of the Second World War, 19 were ready to play a key part in the Battle of Britain, and by the end of the war over 50 had been built. The Germans were aware of the construction of Chain Home but were not sure of its purpose. They tested their theories with a flight of the Zeppelin LZ 130, but concluded the stations were a new long-range naval communications system.

As early as 1936, it was realized that the Luftwaffe would turn to night bombing if the day campaign did not go well, and Watson-Watt had put another of the staff from the Radio Research Station, Edward Bowen, in charge of developing a radar that could be carried by a fighter. Night time visual detection of a bomber was good to about 300 m, and the existing Chain Home systems simply did not have the accuracy needed to get the fighters that close. Bowen decided that an airborne radar should not exceed 90 kg (200 lb) in weight, 8 ft³ (230 L) in volume, and require no more than 500 watts of power. To reduce the drag of the antennas the operating wavelength could not be much greater than one m, difficult for the day's electronics. "AI" - Airborne Interception, was perfected by 1940, and was instrumental in eventually ending the Blitz of 1941.

Watson-Watt justified his choice of a non-optimal frequency for his radar, with his often-quoted “cult of the imperfect,” which he stated as “Give them the third-best to go on with; the second-best comes too late, [and] the best never comes.”

After the War

Ten years after his knighthood, Watson-Watt was awarded £50,000 by the UK government for his contributions in the development of radar. He established a practice as a consulting engineer. In the 1950s, he moved to Canada and later he lived in the US, where he published Three Steps to Victory in 1958. Around 1958, he appeared as a mystery challenger on the American television programme To Tell The Truth.

Watson-Watt reportedly was pulled over for speeding in Canada by a radar gun-toting policeman. His remark was, "Had I known what you were going to do with it I would never have invented it!". He wrote an ironic poem ("Rough Justice") afterwards:

Pity Sir Robert Watson-Watt,

strange target of this radar plot

And thus, with others I can mention,

the victim of his own invention.

His magical all-seeing eye

enabled cloud-bound planes to fly

but now by some ironic twist

it spots the speeding motorist

and bites, no doubt with legal wit,

the hand that once created it.

https://en.wikipedia.org/wiki/Robert_Watson-Watt

The "MacGuffin" Plot Device

In fiction, a MacGuffin (sometimes McGuffin or maguffin) is a plot device in the form of some goal, desired object, or other motivator that the protagonist pursues, often with little or no narrative explanation. The MacGuffin's importance to the plot is not the object itself, but rather its effect on the characters and their motivations. The most common type of MacGuffin is a person, place, or thing (such as money or an object of value). Other more abstract types include victory, glory, survival, power, love, or some unexplained driving force.

The MacGuffin technique is common in films, especially thrillers. Usually the MacGuffin is the central focus of the film in the first act, and thereafter declines in importance. It may reappear at the climax of the story but sometimes is actually forgotten by the end of the story. Multiple MacGuffins are sometimes derisively identified as plot coupons.

History and Use

The use of a MacGuffin as a plot device predates the name "MacGuffin". The Holy Grail of Arthurian Legend has been cited as an example of an early MacGuffin, as a desired object that serves to advance the plot. The World War I-era actress Pearl White used weenie to identify whatever object (a roll of film, a rare coin, expensive diamonds, etc.) impelled the heroes, and often the villains as well, to pursue each other through the convoluted plots of The Perils of Pauline and the other silent film serials in which she starred. In the 1929 detective novel The Maltese Falcon, a small statuette provides both the book's eponymous title and its motive for intrigue.

The name "MacGuffin" was coined by the English screenwriter Angus MacPhail, and was popularized by Alfred Hitchcock in the 1930s.

Alfred Hitchcock

The director and producer Alfred Hitchcock popularized the term "MacGuffin" and the technique with his 1935 film The 39 Steps, an early example of the concept. Hitchcock explained the term "MacGuffin" in a 1939 lecture at Columbia University in New York:

It might be a Scottish name, taken from a story about two men on a train. One man says, 'What's that package up there in the baggage rack?' And the other answers, 'Oh, that's a MacGuffin'. The first one asks, 'What's a MacGuffin?' 'Well,' the other man says, 'it's an apparatus for trapping lions in the Scottish Highlands.' The first man says, 'But there are no lions in the Scottish Highlands,' and the other one answers, 'Well then, that's no MacGuffin!' So you see that a MacGuffin is actually nothing at all.

Interviewed in 1966 by François Truffaut, Hitchcock explained the term "MacGuffin" using the same story.

Hitchcock also said, "The MacGuffin is the thing that the spies are after but the audience don't care."

Hitchcock's term "MacGuffin" helped him to assert that his films were in fact not what they appeared to be on the surface. Hitchcock also related this anecdote in a television interview for Richard Schickel's documentary The Men Who Made the Movies, and in an interview with Dick Cavett.

Screenwriter Angus MacPhail, a friend of Hitchcock, may have originally coined the term, according to author Ken Mogg

George Lucas

On the commentary soundtrack to the 2004 DVD release of Star Wars Episode IV: A New Hope, writer and director George Lucas describes R2-D2 as "the main driving force of the movie … what you say in the movie business is the MacGuffin … the object of everybody's search". In TV interviews, Hitchcock defined a MacGuffin as the object around which the plot revolves, but as to what that object specifically is, he declared, "The audience don't care". In contrast, Lucas believes that the MacGuffin should be powerful and that "the audience should care about it almost as much as the dueling heroes and villains on screen".

Yves Lavandier

For filmmaker and drama writing theorist Yves Lavandier, in the strictly Hitchcockian sense, a MacGuffin is a secret that motivates the villains. North by Northwest's supposed MacGuffin is nothing that motivates the protagonist; Roger Thornhill's objective is to extricate himself from the predicament that the mistaken identity has created, and what matters to Vandamm and the CIA is of little importance to Thornhill. A similar lack of motivating power applies to the alleged MacGuffins of The Lady Vanishes, The 39 Steps, and Foreign Correspondent. In a broader sense, says Lavandier, a MacGuffin denotes any justification for the external conflictual premises of a work.

Examples

Film is a particular user of the MacGuffin technique. Examples from Hitchcock films include plans for a silent plane engine in The 39 Steps, radioactive uranium ore in Notorious, and a clause from a secret peace treaty in Foreign Correspondent. Examples from wider film include the Maltese Falcon in the 1941 film of the same name, the meaning of "Rosebud" in Citizen Kane (1941), the Heart of the Ocean necklace in 1997's Titanic, and the "Rabbit's Foot" in Mission: Impossible III (2006).  Emphasizing the point that the nature of the MacGuffin is not important, in the film Ronin (1998), the MacGuffin is a metallic briefcase whose contents are never revealed. In discussing the mixed critical reception of Indiana Jones and the Kingdom of the Crystal Skull (2008) in which a primary criticism was that the crystal skull in the film was seen as an unsatisfying MacGuffin, director Steven Spielberg said, "I sympathize with people who didn't like the MacGuffin because I never liked the MacGuffin".

In both film and literature, the Holy Grail is often used as a MacGuffin. The 1975 cult classic surreal comedic film Monty Python and the Holy Grail is loosely structured around a knightly quest for the sacred relic. Another well-known example is the infamous briefcase essential throughout 1994's Pulp Fiction. This device closely adheres to the characteristic of "little to no narrative explanation" by never revealing the glowing contents of the briefcase, despite being quintessentially priceless and violently coveted by many major characters.

Examples in television include various Rambaldi artifacts in Alias; the orb in The Adventures of Brisco County, Jr.; and Krieger Waves in the Star Trek: The Next Generation episode "A Matter of Perspective". Carl Macek created protoculture as a MacGuffin to unite the storylines of the three separate anime that composed Robotech. The Hellmouth in Buffy the Vampire Slayer has been described as a kind of topological MacGuffin: "a shortcut, in lieu of scientific explanation", as Joss Whedon put it.

Examples in literature include the television set in Wu Ming's novel 54 and the container in William Gibson's Spook Country.

In the online game The Kingdom of Loathing,  the player's character must eventually complete a long and convoluted quest named "player name and The Quest for the Holy MacGuffin". It involves going to several locations while following clues from the character's father's diary and collecting various items. Eventually it ends in a boss battle and the MacGuffin is returned to the council. The game never reveals what exactly it is or how it will aid in saving the kingdom.

In the Marvel Cinematic Universe, the Infinity Stones serve as MacGuffins.

https://en.wikipedia.org/wiki/MacGuffin#George_Lucas

Treatment of Pimples

A pimple, zit or spot is a kind of comedo and one of the many results of excess oil getting trapped in the pores. Some of the varieties are pustules or papules. Pimples can be treated by various acne medications prescribed by a physician or purchased at a pharmacy with a wide variety of treatments.

Causes of Pimples

Inside the pore are sebaceous glands which produce sebum. When the outer layers of skin shed (as they do continuously), the dead skin cells left behind may become "glued" together by the sebum. This causes a blockage in the pore, especially when the skin becomes thicker at puberty. The sebaceous glands produce more sebum which builds up behind the blockage, and this sebum allows bacteria to grow, including the species Staphylococcus aureus and Propionibacterium acnes, which causes inflammation and infection.

Treatment through over-the-counter medications

Common over-the-counter medications for pimples are benzoyl peroxide and/or salicylic acid and antibacterial agents such as triclosan. Both medications can be found in many creams and gels used to treat acne (acne vulgaris) through topical application. Both medications help skin slough off more easily, which helps to remove bacteria faster. Before applying them the patient needs to wash his or her face with warm water and dry. A cleanser may also be used for that purpose. Acne rosacea is not caused by bacterial infection. It is commonly treated with tretinoin. A regimen of keeping the affected skin area clean plus the regular application of these topical medications is usually enough to keep acne under control, if not at bay altogether. The most common product is a topical treatment of benzoyl peroxide, which has minimal risk apart from minor skin irritation that may present similar as a mild allergy. Recently nicotinamide (vitamin B₃), applied topically, has been shown to be more effective in treatment of pimples than antibiotics such as clindamycin. Nicotinamide is not an antibiotic and has no side effects typically associated with antibiotics. It has the added advantage of reducing skin hyperpigmentation which results in pimple scars.

Treatment through prescription medications

Severe acne usually indicates the necessity of prescription medication to treat the pimples. Prescription medications used to treat acne and pimples include isotretinoin, which is a retinoid. Historically, antibiotics such as tetracyclines and erythromycin were prescribed. While they were more effective than topical applications of benzoyl peroxide, the bacteria eventually grew resistant to the antibiotics and the treatments became less and less effective. Also, antibiotics had more side effects than topical applications, such as stomach cramps and severe discoloration of teeth. Common antibiotics prescribed by dermatologists include doxycycline and minocycline. For more severe cases of acne dermatologists might recommend accutane, a retinoid that is the most potent of acne treatments. However, accutane can cause various side effects including vomiting, diarrhea, and birth defects if taken during pregnancy.

Treatment through hygiene

Practicing good hygiene, including regularly washing skin areas with neutral cleansers, can reduce the amount of dead skin cells and other external contaminants on the skin that can contribute to the development of pimples. However, it is not always possible to completely prevent pimples, even with good hygiene practices as a number of externalities such as hormones and genetics are at play.

Pimple-Popping

Pimple-popping, or zit-popping, is the act of bursting or popping pimples with one's finger. Pimple-popping can lead to the introduction of bacteria into the pimple, infection, the creation of more pimples, and permanent scarring. Thus, popping is usually deprecated by dermatologists and estheticians and it is recommended to let the pimples run through their life span.

                                    https://en.wikipedia.org/wiki/Pimple

Domesticated Horses' Unknown History

Unsaddling Old Theory on Origin of Horses

CNRS, Paris, February 22, 2018 -- Botai horses were tamed in Kazakhstan 5,500 years ago and thought to be the ancestors of today's domesticated horses . . . until a team led by researchers from the CNRS and Université Toulouse III–Paul Sabatier sequenced their genome. Their findings published on 22 February 2018 in Science are startling: these equids are the progenitors not of the modern domesticated horse, but rather of Przewalski's horses—previously presumed wild!

The earliest proof of equine domestication points to the steppes of Central Asia roughly 5,500 years ago. Current models suggest that all modern domesticated horses living now descend from those first tamed in Botai, in the north of present-day Kazakhstan. For CNRS scientist Ludovic Orlando—from the Anthropologie Moléculaire et Imagerie de Synthèse research lab (CNRS / Université Toulouse III – Paul Sabatier / Paris Descartes University)—and his team, sequencing the genomes of 20 of these horses provided a snapshot of biological evolution associated with domestication. Indeed, it is nearly impossible to uncover the earliest stages of domestication through analysis of modern horse genomes, which have been considerably transformed by humans through selective horse breeding.

Yet this genomic analysis yielded unexpected results. Though Botai horses did not give rise to today's domesticated horses, they turn out to be direct ancestors of Przewalski's horses. Thus the latter, commonly thought to be the last wild horses on our planet, are actually the feral descendants of the first horses ever to have been domesticated. The study highlighted certain changes that occurred with this return to a wild state, including the loss of leopard spotting characteristic of the Botai horse. The allele responsible for this coloration was probably eliminated by natural selection as it also caused night blindness.

The team's genomic analysis of twenty-two Eurasian horses, whose lives collectively span the last 4,100 years, has revealed that none are related to the Botai horse. So the origin of modern domestic horses must be sought elsewhere. The researchers are now focusing on other candidate locations in Central Asia as well as on the Pontic-Caspian steppe of southern Russia, in Anatolia, and at various European sites that are refuges for these animals.

                                                     http://www2.cnrs.fr/en/3063.htm

Exploding Star Captured on Film

Amateur Astronomer Captures Rare
First Light of Massive Exploding Star

Keck Observatory,Maunakea, Hawaii – February 21, 2018 -- Thanks to lucky snapshots taken by an amateur astronomer in Argentina, scientists have obtained their first view of the initial burst of light from the explosion of a massive star. 

During tests of a new camera, Víctor Buso captured images of a distant galaxy before and after the supernova's "shock breakout" – when a supersonic pressure wave from the exploding core of the star hits and heats gas at the star’s surface to a very high temperature, causing it to emit light and rapidly brighten. 

To date, no one has been able to capture the "first optical light" from a normal supernova (one not associated with a gamma-ray or x-ray burst), since stars explode seemingly at random in the sky and the light from shock breakout is fleeting. The new data provide important clues to the physical structure of the star just before its catastrophic demise and to the nature of the explosion itself. 

"Professional astronomers have long been searching for such an event," said UC Berkeley astronomer Alex Filippenko, who followed up the discovery with observations at the Lick and Keck observatories that proved critical to a detailed analysis of explosion, called SN 2016gkg. "Observations of stars in the first moments they begin exploding provide information that cannot be directly obtained in any other way." 

"Buso’s data are exceptional," he added. "This is an outstanding example of a partnership between amateur and professional astronomers."

The discovery and results of follow-up observations from around the world will be published in the Feb. 22 issue of the journal Nature (and published online on Feb. 21).

On Sept. 20, 2016, Buso of Rosario, Argentina, was testing a new camera on his 16-inch telescope by taking a series of short-exposure photographs of the spiral galaxy NGC 613, which is about 80 million light years from Earth and located within the southern constellation Sculptor. 

Luckily, he examined these images immediately and noticed a faint point of light quickly brightening near the end of a spiral arm that was not visible in his first set of images. 

Astronomer Melina Bersten and her colleagues at the Instituto de Astrofísica de La Plata in Argentina soon learned of the serendipitous discovery and realized that Buso had caught a rare event, part of the first hour after light emerges from a massive exploding star. 

She estimated Buso's chances of such a discovery, his first supernova, at one in 10 million or perhaps even as low as one in 100 million. 

“It’s like winning the cosmic lottery,” said Filippenko. 

Bersten immediately contacted an international group of astronomers to help conduct additional frequent observations of SN 2016gkg over the next two months, revealing more about the type of star that exploded and the nature of the explosion. 

Filippenko and his colleagues obtained a series of seven spectra, where the light is broken up into its component colors, as in a rainbow, with the Shane 3-meter telescope at the University of California’s Lick Observatory near San Jose, California.

The researchers also performed spectroscopic observations using the Low Resolution Imaging Spectrometer (LRIS) and the DEep Imaging and Multi-Object Spectrograph (DEIMOS) at W. M. Keck Observatory on Maunakea, Hawaii.

The data allowed the international team to determine that the explosion was a Type IIb supernova: the explosion of a massive star that had previously lost most of its hydrogen envelope, a species of exploding star first observationally identified by Filippenko in 1987. 

Combining the data with theoretical models, the team estimated that the initial mass of the star was about 20 times the mass of our sun, though it lost most of its mass, probably to a companion star, and slimmed down to about five solar masses prior to exploding. 

Filippenko’s team continued to monitor the supernova’s changing brightness over two months with other Lick telescopes: the 0.76-meter Katzman Automatic Imaging Telescope and the 1- meter Nickel telescope.

“The Lick spectra, obtained with just a 3-meter telescope, are of outstanding quality in part because of a recent major upgrade to the Kast spectrograph, made possible by the Heising- Simons Foundation as well as William and Marina Kast,” Filippenko said. 

Filippenko’s group, which included numerous undergraduate students, is supported by the Christopher R. Redlich Fund, Gary and Cynthia Bengier, the TABASGO Foundation, the Sylvia and Jim Katzman Foundation, many individual donors, the Miller Institute for Basic Research in Science and NASA through the Space Telescope Science Institute. Research at Lick Observatory is partially supported by a generous gift from Google.

       Link with pictures:  http://www.keckobservatory.org/recent/entry/shock_breakout

Observing Ultra-Fast Ionization

A Quadrillionth of a Second in Slow Motion
Observing and controlling ultrafast processes with attosecond resolution

Technical University of Munich – February 20, 2018 -- Many chemical processes run so fast that they are only roughly understood. To clarify these processes, a team from the Technical University of Munich (TUM) has now developed a methodology with a resolution of quintillionths of a second. The new technology stands to help better understand processes like photosynthesis and develop faster computer chips.

An important intermediary step in many chemical processes is ionization. A typical example of this is photosynthesis. The reactions take only a few femtoseconds (quadrillionths of a second) or even merely a few hundred attoseconds (quintillionths of a second). Because they run so extremely fast, only the initial and final products are known, but not the reaction paths or the intermediate products.

To observe such ultrafast processes, science needs a measurement technology that is faster than the observed process itself. So-called “pump-probe spectroscopy” makes this possible.

Here, the sample is excited using an initial laser pulse, which sets the reaction into motion. A second, time-delayed pulse queries the momentary state of the process. Multiple repetitions of the reaction with different time delays result in individual stop-motion images, which can then be compiled into a “film clip”.

Two eyes see more than one

Now, a team of scientists headed by Birgitta Bernhardt, a former staff member at the Chair of Laser and X-ray Physics at TU Munich and meanwhile junior professor at the Institute of Applied Physics at the University of Jena, have for the first time succeeded in combining two pump-probe spectroscopy techniques using the inert gas krypton. This allowed them to shed light on the ultrafast ionization processes in a precision that has simply not been possible hitherto.

“Prior to our experiment, one could observe either which part of the exciting light was absorbed by the sample over time or measure what kind of and how many ions were created in the process,” explains Bernhardt. “We have now combined the two techniques, which allows us to observe the precise steps by which the ionization takes place, how long these intermediate products exist and what precisely the exciting laser pulse causes in the sample.”

Ultrafast processes under control

The combination of the two measuring techniques allows the scientists not only to record the ultrafast ionization processes. Thanks to the variation in the intensity of the second, probing laser pulse, they can now, for the first time, also control and in this way also influence the ionization dynamics.

“This kind of control is a very powerful instrument,” explains Bernhardt. “If we can precisely understand and even influence fast ionization processes, we are able to learn a lot about light-driven processes like photosynthesis – especially about the initial moments in which this complex machinery is set into motion and which is hardly understood to date.”

Ultrafast computers

The technology developed by Bernhardt and her colleagues is also interesting for the development of new, faster computer chips in which the ionization of silicon plays a significant role. If the ionization states of silicon can not only be sampled on such a short time scale, but can also be set – as the first experiments with krypton suggest – scientists might one day be able to use this to develop novel and even faster computer technologies.

https://www.tum.de/nc/en/about-tum/news/press-releases/detail/article/34499/

Neuromancer Author William Gibson

William Ford Gibson (born March 17, 1948) is a Canadian-American speculative fiction writer and essayist widely credited with pioneering the science fiction subgenre known as cyberpunk. Beginning his writing career in the late 1970s, his early works were noir, near-future stories that explored the effects of technology, cybernetics, and computer networks on humans—a "combination of lowlife and high tech"—and helped to create an iconography for the information age before the ubiquity of the Internet in the 1990s. Gibson notably coined the term "cyberspace" in his short story "Burning Chrome" (1982) and later popularized the concept in his acclaimed debut novel Neuromancer (1984). These early works have been credited with "renovating" science fiction literature after it had fallen largely into insignificance in the 1970s.

                                                            William Gibson in 2008

After expanding on Neuromancer with two more novels to complete the dystopic Sprawl trilogy, Gibson collaborated with Bruce Sterling on the alternate history novel The Difference Engine (1990), which became an important work of the science fiction subgenre steampunk. In the 1990s, Gibson composed the Bridge trilogy of novels, which explored the sociological developments of near-future urban environments, postindustrial society, and late capitalism. Following the turn of the century and the events of 9/11, Gibson emerged with a string of increasingly realist novels—Pattern Recognition (2003), Spook Country (2007), and Zero History (2010)—set in a roughly contemporary world. These works saw his name reach mainstream bestseller lists for the first time. His more recent novel, The Peripheral (2014), returned to a more overt engagement with technology and recognizable science fiction concerns.

In 1999, The Guardian described Gibson as "probably the most important novelist of the past two decades," while the Sydney Morning Herald called him the "noir prophet" of cyberpunk. Throughout his career, Gibson has written more than 20 short stories and 10 critically acclaimed novels (one in collaboration), contributed articles to several major publications, and collaborated extensively with performance artists, filmmakers, and musicians. His work has been cited as an influence across a variety of disciplines spanning academia, design, film, literature, music, cyberculture, and technology.

Writing Neuromancer

Neuromancer was commissioned by Terry Carr for the second series of Ace Science Fiction Specials, which was intended to exclusively feature debut novels. Given a year to complete the work, Gibson undertook the actual writing out of "blind animal terror" at the obligation to write an entire novel – a feat which he felt he was "four or five years away from". After viewing the first 20 minutes of landmark cyberpunk film Blade Runner (1982) which was released when Gibson had written a third of the novel, he "figured [Neuromancer] was sunk, done for. Everyone would assume I'd copped my visual texture from this astonishingly fine-looking film." He re-wrote the first two-thirds of the book twelve times, feared losing the reader's attention and was convinced that he would be "permanently shamed" following its publication; yet what resulted was a major imaginative leap forward for a first-time novelist.

Neuromancer's release was not greeted with fanfare, but it hit a cultural nerve, quickly becoming an underground word-of-mouth hit. It became the first winner of one science fiction "triple crown" —both Nebula and Hugo Awards as the year's best novel and Philip K. Dick Award as the best paperback original— eventually selling more than 6.5 million copies worldwide.

Lawrence Person in his "Notes Toward a Postcyberpunk Manifesto" (1998) identified Neuromancer as "the archetypal cyberpunk work", and in 2005, Time included it in its list of the 100 best English-language novels written since 1923, opining that "[t]here is no way to overstate how radical [Neuromancer] was when it first appeared." Literary critic Larry McCaffery described the concept of the matrix in Neuromancer as a place where "data dance with human consciousness... human memory is literalized and mechanized... multi-national information systems mutate and breed into startling new structures whose beauty and complexity are unimaginable, mystical, and above all nonhuman." Gibson later commented on himself as an author, circa Neuromancer, that "I'd buy him a drink, but I don't know if I'd loan him any money," and referred to the novel as "an adolescent's book". The success of Neuromancer was to effect the 35-year-old Gibson's emergence from obscurity.

                                https://en.wikipedia.org/wiki/William_Gibson

Volcano Forms in Cornfield

Parícutin (or Volcán de Parícutin, also accented Paricutín) is a cinder cone volcano located in the Mexican state of Michoacán, near the city of Uruapan and about 322 kilometres (200 mi) west of Mexico City. The volcano surged suddenly from the cornfield of local farmer Dionisio Pulido in 1943, attracting both popular and scientific attention.

                                                           Paricutin erupting in 1943 
Paricutín presented the first occasion for modern science to document the full life cycle of an eruption of this type. During the volcano's nine years of activity, scientists sketched and mapped it and took thousands of samples and photographs. By 1952, the eruption had left a 424-meter-high (1,391 ft) cone and significantly damaged an area of more than 233 square kilometres (90 sq mi) with the ejection of stone, volcanic ash and lava. Three people were killed, two towns were completely evacuated, and buried by lava and three others were heavily affected. Hundreds of people had to be permanently relocated, and two new towns were created to accommodate their migration. Although the larger region still remains highly active volcanically, Parícutin is now dormant and has become a tourist attraction with people climbing the volcano and visiting the hardened lava-covered ruins of the San Juan Parangaricutiro Church. In 1997, CNN included Parícutin in its list of the Seven Natural Wonders of the World.

Detailed Description

Parícutin is located in the Mexican municipality of Nuevo Parangaricutiro, Michoacán, 29 kilometres (18 mi) west of the city of Uruapan and about 322 km west of Mexico City. It lies on the northern flank of the Cerros de Tancítaro, which itself lies on top of an old shield volcano and extends 3,170 meters (10,400 ft) above sea level and 424 meters (1,391 ft) above the Valley of Quitzocho-Cuiyusuru, wedged against old volcanic mountain chains and surrounded by small volcanic cones with the intervening valleys occupied by small fields and orchards or small settlements, from groups of a few houses to those the size of towns.

The volcano lies on, and is a product of, the Trans-Mexican Volcanic Belt, which runs 900 kilometres (560 mi) west-to-east across central Mexico. It includes the Sierra Nevada mountain range (a set of extinct volcanoes) as well as thousands of cinder cones and volcanic events. Volcanic activity here has created the Central Mexican Plateau and rock deposits up to 1.8 kilometres (1.1 mi) deep. It has also created fertile soils by the widespread deposition of ash and thereby some of Mexico’s most productive farmland. The volcanic activity here is a result of the subduction of the Rivera and Cocos plates along the Middle America Trench. More specifically, the volcano is the youngest of the approximately 1,400 volcanic vents of the Michoacán-Guanajuato volcanic field, a 40,000 square kilometres (15,000 sq mi) basalt plateau filled with scoria cones like Parícutin, along with small shield volcanoes, maars, tuff rings and lava domes. Scoria cones are the most common type of volcano in Mexico, appearing suddenly and building a cone-shaped mountain with steep slopes before going extinct. Parícutin's immediate predecessor was El Jorullo, also in Michoacán, which erupted in 1759.

Currently the crater of the volcano is about 200 meters (660 ft) across and it is possible to both climb the volcano and walk around the entire perimeter. Although classified as extinct by scientists, Parícutin is still hot, and seeping rainwater reacts with this heat so that the cone still emits steam in various streams. The forces that created the volcano are still active. In 1997 there was a vigorous swarm of 230 earthquakes in the Parícutin area due to tectonic movement, with five above 3.9 on the moment magnitude scale. There were also some reports of rumbling in 1995 and of black steam and rumbling in 1998. In the summer of 2006, there was another major volcanic earthquake swarm, with over 300 located near the volcano, indicating magma movement, but with no eruption at Parícutin or anywhere else.

Formation of Paricutin

Parícutin erupted from 1943 to 1952, unusually long for this type of volcano, and with several eruptive phases. For weeks prior, residents of the area reported hearing noises similar to thunder but without clouds in the sky. This sound is consistent with deep earthquakes from the movement of magma. A later study indicated that the eruption was preceded by 21 earthquakes over 3.2 in intensity starting five weeks before the eruption. One week prior to the eruption, newspapers reported 25–30 per day. The day before the eruption, the number is estimated at 300.

The eruption began on February 20, 1943, at about 4:00 PM local time. The center of the activity was a cornfield near the town of Parícutin, owned by Dionisio Pulido. During that day, he and his family had been working their land, clearing it to prepare for spring planting. Suddenly the ground nearby where they were working swelled upward and formed a fissure between 2 and 2.5 meters across. They reported that they heard hissing sounds, and smoke which smelled like rotten eggs, indicating the presence of hydrogen sulfide. Within hours, the fissure would develop into a small crater.

Pulido reported:

At 4 p.m., I left my wife to set fire to a pile of branches when I noticed that a crack, which was situated on one of the knolls of my farm, had opened . . . and I saw that it was a kind of fissure that had a depth of only half a meter. I set about to ignite the branches again when I felt a thunder, the trees trembled, and I turned to speak to Paula; and it was then I saw how, in the hole, the ground swelled and raised itself 2 or 2.5 meters high, and a kind of smoke or fine dust – grey, like ashes – began to rise up in a portion of the crack that I had not previously seen . . . Immediately more smoke began to rise with a hiss or whistle, loud and continuous; and there was a smell of sulfur.

He tried to find his family and oxen but they had disappeared so he rode his horse to town where he found his family and friends, happy to see him alive. The volcano grew fast and furiously after this. Witness Celedonio Gutierrez, who witnessed the eruption on the first night reported:

…when night began to fall, we heard noises like the surge of the sea, and red flames of fire rose into the darkened sky, some rising 800 meters or more into the air, that burst like golden marigolds, and a rain like artificial fire fell to the ground.

On that first day, the volcano had begun strombolian pyroclastic activity and within 24 hours, there was a scorian cone fifty meters high, created by the ejection of lapilli fragments up to the size of a walnut and larger, semi-molten volcanic bombs. By the end of the week, reports had the cone between 100 and 150 meters high. Soon after the start, the valley was covered in smoke and ash. The nine-year activity of the volcano is divided into four stages with names that come from the Purépecha language. The first phase (Quitzocho) extended from February 22 to October 18, 1943, with activity concentrated in the cracks that formed in the Cuiyusuro Valley, forming the initial cone. During this time, the ejected material was mostly lapilli and bombs. In March, the eruption became more powerful, with eruptive columns that extended for several kilometers. In four months, the cone reached 200 meters and in eight months 365 meters. During this time period, there was some lava flow. On June 12, lava began to advance towards the village of Parícutin, forcing evacuations the next day. The second phase went from October 18, 1943 to January 8, 1944 and is called Sapichi, meaning "child", referring to the formation of a lateral vent and other openings on the north side of the cone. Ash and bombs continued to be ejected but the new vent sent lava towards the town of San Juan Parangaricutiro, forcing its permanent evacuation. By August, the town was completely covered in lava and ash, with only the upper portions of the main church still visible. The evacuations of Parícutin and San Juan were able to be accomplished without loss of life due to the slow movement of the lava. These two phases lasted just over a year and account for more than 90% of the total material ejected from the cone, as well as almost four-fifths (330 meters) of the final height of 424 meters from the valley floor. It also sent ash as far as Mexico City.

https://en.wikipedia.org/wiki/Par%C3%ADcutin

Malacidins Kill Deadly Bacteria

Malacidins are a class of chemicals made by bacteria found in soil that kill Gram-positive bacteria. Their activity appears to be dependent on calcium. The discovery of malacidins was published in 2018.

The malacidin family were discovered using a new method of soil microbiome screening, which allowed researchers to identify genetic components necessary to produce the chemical. Malacidin A was shown to kill Staphylococcus aureus and other Gram-positive bacteria.

At the time of the publication it was not certain if the discovery would lead to any new antibiotic drugs because large investments of time and money are required to determine if a drug is safe and effective.

 

Chemical Structure

Malacidins are macrocycle lipopeptides. The 2018 paper described two chemicals in the malacidin family, differing only by a methylene at their lipid tails. Their peptide cores include four non-proteinogenic amino acids. The name "malacidin" is derived from the abbreviation of metagenomic acidic lipopeptide antibiotic and the suffix –cidin.

Mechanism of Action

Malacidins appear to take on their active conformation after they bind to calcium; the calcium-bound molecule then appears to bind to lipid II, a bacterial cell wall precursor molecule, leading to destruction of the cell wall and death of the bacteria. Therefore, they would be a new member of the class of calcium-dependent antibiotics. The discovery of malacidins supported the view that the calcium-dependent antibiotics are a larger class than previously thought.

History

Malacidins were discovered by researchers at Rockefeller University, led by Brad Hover and Sean Brady. The group had been looking into antibiotics related to daptomycin and their calcium-dependent nature, but determined that it would be impractical to culture variations in lab conditions. Instead, the team used a genetics approach that was more scalable. They focused on searching for novel biosynthetic gene clusters (BGCs) – genes that are usually expressed together, that bacteria use to make secondary metabolites. To do this, they extracted DNA from around 2,000 soil samples to build metagenomic libraries that captured the genetic diversity of the environmental microbiome. They then designed degenerate primers to amplify genes likely to be similar to the BGC that make daptomycin by using a polymerase chain reaction (PCR) procedure, sequenced the amplified genes, and then used metagenomics to confirm that these genes were indeed likely to be the kind of BGCs they sought. One of the novel BGCs they found was present in around 19% of the screened soil samples but not readily found in cultured microbial collections, so they took that BGC, put it into other host bacteria, and then isolated and analyzed the secondary metabolites.  The work was published in Nature Microbiology in February 2018.

Research Directions

The approach of screening the soil for useful compounds using genomics has been done by others, and is likely to continue to be pursued as a method to further explore primary metabolites and secondary metabolites made by microrganisms.

As of 2018, the malacidins have not been tested on humans. At the time of their discovery it was unknown whether the discovery would lead to any new antibiotic drugs; showing that a potential drug is safe and effective takes years of work and millions of dollars, and the scientists said at the time that they had no plans to try to develop a drug based on the work. In the 2018 paper, malacidins were shown to kill only Gram-positive bacteria and not Gram-negative bacteria. They were, however, able to kill multidrug-resistant pathogens, including bacteria resistant to vancomycin in the laboratory, and methicillin-resistant Staphylococcus aureus (MRSA) skin infections in an animal wound model.

Brady, Hover, and two other authors disclosed in the 2018 paper that they had "competing financial interests as they are employees or consultants of Lodo Therapeutics." Lodo was founded in 2016 out of Brady's lab, to discover new chemicals in nature as starting points for drug discovery.

See also

• Teixobactin
• Daptomycin
• Friulimicin

                                https://en.wikipedia.org/wiki/Malacidin