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  • richardmitnick 8:00 am on October 11, 2017 Permalink | Reply
    Tags: , , , Confirmed: cosmic rays blast from supernovae, Cosmic rays – high energy subatomic particles – are produced within at least one supernova, , GHaFaS, Weizmann Institute of Science   

    From Weizmann via COSMOS: “Confirmed: cosmic rays blast from supernovae” 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    COSMOS
    11 October 2017
    Andrew Masterson

    An exploded star first seen by 500 years ago helps astrophysicists to solve a cosmic conundrum.

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    Left. Composite image of the remnant of Tycho Brahe’s supernova (1572) using data from the Chandra x-ray satellite observatory (yellow, green, blue (credits NASA/SAO), from the Spitzer infrared satellite observatory (red, credits, NASA/JPL-Caltech), and from the Calar Alto observatory (stars white, credit, Krause et al.). The transparent magenta box shows the field of the ACAM instrument at the Cassegrain focus of the William Herschel Telescope (WHT, ORM, La Palma). Centre, a zoom-in on the ACAM field with a green box showing the size of the field of the 2d spectrograph GHaFaS (WHT, ORM). Right. The reduced and integrated image of GHaFaS in the emission from ionized hydrogen (Ha). NASA/SAO, NASA/JPL-Caltech

    Ending an astronomical mystery, scientists have confirmed that cosmic rays – high energy subatomic particles – are produced within at least one supernova.

    The rays, which consist primarily of protons and atomic nuclei, continuously bombard the Earth’s atmosphere. It’s been known for decades that they originate from outside the solar system, even perhaps outside the galaxy, but how and where they are created has until now remained obscure.

    Now research published in The Astrophysical Journal finds that an as yet unknown mechanism within exploding stars is the likely source. The mechanism acts as an accelerator, producing an unexpectedly wide range of particle velocities that cannot be accounted for by the mass and temperature of the gases involved.

    The discovery was made by a team led by astrophysicist Sladjana Knežević of the Weizmann Institute of Science in Israel, using as instrument known as GHaFaS, mounted on the 4.2m William Herschel Telescope at the Roque de los Muchachos Observatory in the Canary Islands.


    ING 4 meter William Herschel Telescope at Roque de los Muchachos Observatory on La Palma in the Canary Islands, 2,396 m (7,861 ft)

    The team focussed the instrument’s attention on a supernova known formally as SN 1572, but more commonly as Tycho’s supernova, after the pioneering astronomer Tycho Brahe who first recorded its existence in in 1572.

    3
    Remnant of SN 1572 as seen in X-ray light from the Chandra X-ray Observatory

    NASA/Chandra Telescope

    The supernova – more correctly, a supernova remnant – has been studied several times in recent years, including by British radio-astronomers in the 1950s, and observers at the California’s Mount Palomar Observatory a decade later. NASA’s orbiting Chandra X-ray Observatory imaged it in 2002

    Caltech Palomar Observatory, located in San Diego County, California, US, at 1,712 m (5,617 ft)

    None of these investigations, however, had sufficient resolution to test the hypothesis that supernovae may be the source of cosmic rays.

    Using the Canary Islands facility, Knežević and his colleagues mapped a section of the dissipating cloud that surrounds the Tycho remnant, including a bright, visible filament. Measuring two levels of hydrogen emission spread, the team found that the results only made sense if somewhere in the remnant an accelerator was producing high energy particles.

    The finding is the first time evidence for such a mechanism has been found, and appears to confirm supernovae as the source of cosmic rays.

    The data has important implications for both astrophysics and particle physics.

    The researchers now intend to combine their results with other measurements of Tycho’s supernova already taken by another facility on the Canary Islands, the larger Gran Telescopio Canariasto, to gain a clearer picture of cosmic ray acceleration.


    Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level

    See the full article here .

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

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  • richardmitnick 12:29 pm on July 9, 2017 Permalink | Reply
    Tags: , , , Weizmann Institute of Science   

    From APS Physics: “Cooperating Lasers Make Topological Defects” 

    Physics LogoAbout Physics

    Physics Logo 2

    Physics

    July 7, 2017
    David Ehrenstein

    1
    A circle of ten interacting lasers (left) can cleanly synchronize their phases, as shown by the sharp distinctions between light and dark rings near the center. But using 20 lasers (right) leads to a 20% likelihood for topological defects, where each laser’s phase is offset from its neighbors’, leading to light and dark rings that are less sharply defined. V. Pal et al., Phys. Rev. Lett. (2017).

    If you cool molten iron slowly, the electron spins can gradually align in a single direction and produce a strong magnetic field. But rapid cooling leads to magnetic domains aligned in various directions, separated by thin boundaries called topological defects. A similar phenomenon may have occurred as the Universe rapidly cooled after the big bang. To study topological defect formation in the lab without the challenges of temperature control, Nir Davidson and colleagues at the Weizmann Institute, Israel, have now developed an experimental model involving interacting laser beams.

    Weizmann Institute Campus

    Imaging the laser intensities allows them to measure the likelihood for topological defects to form for a range of parameters such as the effective “cooling rate.”

    To create their experimental model, Davidson and colleagues placed a disk containing between 10 and 30 holes arranged in a circle inside a laser cavity. This “mask” produced a set of laser beams, each emerging from a different hole and leaking a bit into its two neighboring beams, generating interactions. These interactions caused the phase differences among the beams to change over time. The evolution was so rapid that the team simply observed the final state, by recording the resulting pattern of laser intensities.

    This state represented the combined effects of about 1000 different longitudinal modes in the cavity—essentially 1000 independent experiments running simultaneously, each with a different set of initial phase relationships among the lasers. In many cases, the beams quickly synchronized their phases, but for some initial phase relationships, the beams would get “stuck” in a state where each beam was a fixed phase away from its neighbors. The team showed that, with ten lasers, there are exactly eight of these topological defect states.

    Analysis of the laser patterns allowed the researchers to measure the likelihood of topological defect formation as they varied parameters such as the number of lasers in the ring and the power of the pump light inside the cavity. They found that, with increasing pump power, topological defects became increasingly likely. The team explains this result with simulations showing that the variations in intensity among the beams drop rapidly in time when the pump power is high, whereas low power is associated with slower intensity equilibration. They say that the slower equilibration is the equivalent of a slower cooling rate, and thus, a lower likelihood for topological defects.

    This research is published in Physical Review Letters

    See the full article here .

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    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments (physics@aps.org).

     
  • richardmitnick 11:55 am on June 11, 2017 Permalink | Reply
    Tags: , Dr. Binghai Yan, , Topological materials, Weizmann Institute of Science   

    From Weizmann: “Physics on the edge” 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    1
    Dr. Binghai Yan

    Dr. Binghai Yan is taking topological materials higher.

    Creating new materials for everyday life—think bendable electronics, quantum computers, life-saving medical devices and things we haven’t yet dreamed of—requires understanding and creatively brainstorming new possibilities at the atomic level.

    This is the essence Dr. Binghai Yan’s research. His field is topological materials, which is fusing theoretical science with practical engineering and taking the physics world by storm. And yes, his name gives away the other special news: he is the first principal investigator from China hired by the Weizmann Institute.

    Topological materials and states involve a kind of order very different from conventional bulk materials in that electrons (and their lattices of atoms and molecules) on the surface of a crystal or other material behave differently than those in the material itself. In is the special nature of such topological materials and states that can be leveraged for the creation of new materials. He straddles the world of theory—how such states could work—and experimentation—trying out the materials to synthesize new materials and devices such as quantum computers.

    From rural fields to topology

    So how did a Chinese physicist who grew up in a remote farming village in Shandong Province in eastern China make his way to the Weizmann Institute?

    After completing his BSc at Xi’an Jiatong University in Xi’an in 2003, he earned a PhD in physics at the Tsinghua University in Beijing in 2008. He did postdoctoral research at the University of Bremen in Germany, when the field of topological research was beginning to take off. But it was still a relatively niche subject in which few physicists were working. Thanks to a flexible postdoc grant, the prestigious Humboldt Research Fellowship, which allowed him to spend time at other institutions, he spent eight months at Stanford University learning from a leading expert in the field.

    He returned to Germany to become a group leader (the equivalent of a principal investigator) at the Max Planck Institute for Chemical Physics and Solids in Dresden. It was then that he began collaborating with Weizmann Institute colleagues—thanks to an introduction by Prof. Ady Stern at a conference in Germany—including Prof. Erez Berg and Dr. Haim Beidenkopf, all from the Department of Condensed Matter Physics. The collaboration was enabled by an ARCHES Award given by Germany’s Minerva Foundation, which stimulates collaborative projects by German and Israeli scientists. He visited the Weizmann Institute for the first time in 2013 to advance this work.

    The project and the visit were a “fantastic opportunity,” he says, because his Weizmann collaborators were both theoreticians and experimentalists who were eager to learn about the material he was working on—and Dr. Yan needed feedback from theory to advance his investigations by predicting possible new materials and actualize his ideas in experiments. “I immediately realized that we have lots to do,” he says. “Together, we are able to bridge fundamental physics and experimentation.”

    Last year, he received a competing offer from a university in China, but took the Weizmann offer “because of my existing collaborations and potential collaborations, the depth of theory and experiment work here, and the fact that Weizmann is one of the few places that is advancing this field,” he says.

    Dr. Yan has already discovered a new class of topological materials: a three-dimensional, layered, metallic insulating material which he grows in the lab. He has done so by way of his expertise in electron charge and spin, and so this research has implications for the new, hot field of “spintronics”. Spintronics differs from traditional electronics in that it leverages the way in which electrons spin—not only their charge—to find better efficiency with data storage and transfer. This, in turn, has relevance for the new age of quantum computing, and he hopes to collaborate with quantum computing pioneers at the Institute.

    For his wife, Huanhuan Wang, the decision to make a potentially permanent move to Israel—a country she’d never before visited and about which she had little knowledge—was not as obvious as it was for Dr. Yan. “It took a little bit of convincing my wife to come; if you’ve never been here, all you think is political strife,” says Dr. Yan. “But the reality is different. We are really happy here and it is quickly starting to feel like home.”

    The family arrived in February and moved into campus housing. His wife is now pursuing a PhD under the guidance of Prof. Dan Yakir in the Department of Plant and Environmental Sciences. They have two kids, a boy and a girl, who just began learning German, and now are getting used to Hebrew—and they speak Chinese at home.

    Dr. Yan is finding opportunities to collaborate with scientists in Germany and China, and has already begun organizing a workshop on topological systems at the Weizmann Institute (together with Dr. Haim Beidenkopf and Dr. Nurit Avraham, also of the Department of Physics of Condensed Matter Physics), to which he has invited leading European and Chinese physicists and other leaders in the field.

    “Being in Israel, at Weizmann, is not something that I would have anticipated five or 10 years ago,” he says. “But life—like the materials of the future—holds many mysteries.”

    Dr. Yan is supported by the Ruth and Herman Albert Scholars Program for New Scientists.

    See the full article here .

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
  • richardmitnick 3:13 pm on May 22, 2017 Permalink | Reply
    Tags: A lack of the protein citrin slows children's growth; blocking it in cancer slows tumor growth., , , Dr. Ayelet Erez, , Weizmann Institute of Science,   

    From Weizmann: Women in STEM – “Rare Genetic Defect May Lead to Cancer Drug” Dr. Ayelet Erez 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    17.05.2017
    No writer credit found

    1
    Dr. Ayelet Erez says rare genetic diseases provide a lens on cancer.

    A lack of the protein citrin slows children’s growth; blocking it in cancer slows tumor growth.

    The path to understanding what goes wrong in cancer could benefit from a detour through studies of rare childhood diseases. Dr. Ayelet Erez explains that cancer generally involves dozens – if not hundreds – of mutations, and sorting out the various functions and malfunctions of each may be nearly impossible. Rare childhood diseases, in contrast, generally involve mutations to a single gene. Erez, a geneticist and medical doctor who treats families with genetic cancer in addition to heading a research lab in the Weizmann Institute of Science’s Biological Regulation Department, says that children with rare genetic syndromes may serve as a “lens” when trying to understand the role of a specific gene in a complex disease such as cancer. She and her team have been focusing their sights on a protein they discovered in this way; promising lab tests indicate that blocking this protein might slow the progression of some cancers.

    Her findings place this research in the new field of “cancer metabolism,” which seeks to understand how the aberrant, or uncontrolled metabolic processes in cancers might turned against them to stop their growth.

    She and her team studied cells from children suffering from an extremely rare disease, citrullinemia type II, who are missing the gene for a protein called citrin. Clinically, children with this disease tend to be smaller than average, and to avoid candy. Her research revealed that this protein normally helps keep the body supplied with an amino acid called aspartate which is required to produce DNA and RNA in addition to the breakdown of glucose; so deficiency in this protein causes the cells to divide less.

    Research into another genetic childhood disease, citrullinemia type I, had already given the team the lens they needed to understand how cancer cells rely on aspartate to divide and migrate. Children born with this disease are missing a gene called ASS1; the lack of ASS1 connects the disease to particularly aggressive, hard-to-treat cancers in which this gene tends to be silenced or mutated. Since this gene also requires aspartate to function, Erez and her team surmised that the silencing had less to do with the gene’s function and more with competition for aspartate and the cancer cells’ craving for ever more of this amino acid to help them divide and spread. Interestingly, the dependence on citrin for aspartate supplementation is seen in cancers both with and without ASS1 expression.

    Ayelet and her team realized that citrin – the protein that helps regulate childhood growth – could present a possible target for anticancer therapies. Blocking this protein would hopefully disrupt the cancer’s overactive metabolic cycle, diminish the cancer cells’ aspartate supply and slow their growth, thus making them less aggressive, less likely to spread and possibly more treatable with other, conventional means. To that end, Erez and her group have been developing a molecule to block citrin, and testing it in the lab. Yeda Research and Development Co., Ltd., the technology transfer arm of the Weizmann Institute of Science, is working with Erez to advance her research to the point that it can be developed for biomedical application.

    Dr. Ayelet Erez’s research is supported by the Moross Integrated Cancer Center; the Irving B. Harris Fund; the Adelis Foundation; the Rising Tide Foundation; the Comisaroff Family Trust; and the European Research Council. Dr. Erez is the incumbent of the Leah Omenn Career Development Chair.

    See the full article here .

    Please help promote STEM in your local schools.

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
  • richardmitnick 11:37 am on March 14, 2017 Permalink | Reply
    Tags: , , , , , Weizmann Institute of Science   

    From Weizmann: “Explosive Material: The Making of a Supernova” 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    Pre-supernova stars may show signs of instability for months before the big explosion

    14.03.2017

    In the most common type of supernova, the iron core of a massive star suddenly collapses in on itself and the outer layers are thrown out into space in a spectacular explosion. New research led by Weizmann Institute of Science researchers shows that the stars that become so-called core-collapse supernovae might already exhibit instability for several months before the big event, spewing material into space and creating a dense gas shell around themselves. They think that many massive stars, including the red super-giants that are the most common progenitors of these supernovae, may begin the process this way.

    This insight into the conditions leading up to core collapse arose from a unique collaboration called the Palomar Transient Factory, a fully automated sky survey using the telescopes of the Palomar observatory in southern California.


    Palomar Transient Factory, located in San Diego County, California

    Astrophysicists halfway around the globe, in Israel, are on call for the telescope, which scans the California night sky for the sudden appearance of new astronomical “transients” that were not visible before – which can indicate new supernovae. In October, 2013, Dr. Ofer Yaron, in the Weizmann Institute’s Particle Physics and Astrophysics Department, got the message that a potential supernova had been sighted, and he immediately alerted Dr. Dan Perley who was observing that night with the Keck telescope in Hawaii, and NASA’s Swift Satellite.


    Keck Observatory, Mauna Kea, Hawaii, USA


    NASA/SWIFT Telescope

    At Keck, the researchers soon began to record the spectra of the event. Because they had started observing only three hours into the blast, the picture the team managed to assemble was the most detailed ever of the core collapse process. “We had x-rays, ultraviolet, four spectroscopic measurements from between six and ten hours post-explosion to work with,” says Yaron.

    In the most common type of supernova, the iron core of a massive star suddenly collapses in on itself and the outer layers are thrown out into space in a spectacular explosion. New research led by Weizmann Institute of Science researchers shows that the stars that become so-called core-collapse supernovae might already exhibit instability for several months before the big event, spewing material into space and creating a dense gas shell around themselves. They think that many massive stars, including the red super-giants that are the most common progenitors of these supernovae, may begin the process this way.

    This insight into the conditions leading up to core collapse arose from a unique collaboration called the Palomar Transient Factory, a fully automated sky survey using the telescopes of the Palomar observatory in southern California. Astrophysicists halfway around the globe, in Israel, are on call for the telescope, which scans the California night sky for the sudden appearance of new astronomical “transients” that were not visible before – which can indicate new supernovae. In October, 2013, Dr. Ofer Yaron, in the Weizmann Institute’s Particle Physics and Astrophysics Department, got the message that a potential supernova had been sighted, and he immediately alerted Dr. Dan Perley who was observing that night with the Keck telescope in Hawaii, and NASA’s Swift Satellite. At Keck, the researchers soon began to record the spectra of the event. Because they had started observing only three hours into the blast, the picture the team managed to assemble was the most detailed ever of the core collapse process. “We had x-rays, ultraviolet, four spectroscopic measurements from between six and ten hours post-explosion to work with,” says Yaron.

    In a study recently published in Nature Physics, Yaron, Weizmann Institute researchers Profs. Avishay Gal-Yam and Eran Ofek, and their teams, together with researchers from the California Institute of Technology and other institutes in the United States, Denmark, Sweden, Ireland, Israel and the UK, analyzed the unique dataset they had collected from the very first days of the supernova.

    The time window was crucial: It enabled the team to detect material that had surrounded the star pre- explosion, as it heated up and became ionized and was eventually overtaken by the expanding cloud of stellar matter. Comparing the observed early spectra and light-curve data with existing models, accompanied by later radio observations, led the researchers to conclude that the explosion was preceded by a period of instability lasting for around a year. This instability caused material to be expelled from the surface layers of the star, forming the circumstellar shell of gas that was observed in the data. Because this was found to be a relatively standard type II supernova, the researchers believe that the instability they revealed may be a regular warm up act to the immanent explosion.

    “We still don’t really understand the process by which a star explodes as a supernova,” says Yaron, “These findings are raising new questions, for example, about the final trigger that tips the star from merely unstable to explosive. With our globe-spanning collaboration that enables us to alert various telescopes to train their sights on the event, we are getting closer and closer to understanding what happens in that instant, how massive stars end their life and what leads up to the final explosion.”

    2

    Prof. Avishay Gal-Yam’s research is supported by the Benoziyo Endowment Fund for the Advancement of Science; the Yeda-Sela Center for Basic Research; the Deloro Institute for Advanced Research in Space and Optics; and Paul and Tina Gardner. Prof. Gal-Yam is the recipient of the Helen and Martin Kimmel Award for Innovative Investigation.

    Dr. Eran Ofek’s research is supported by the Helen Kimmel Center for Planetary Science; Paul and Tina Gardner, Austin, TX; Ilan Gluzman, Secaucus, NJ; and the estate of Raymond Lapon.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
  • richardmitnick 10:11 am on March 1, 2017 Permalink | Reply
    Tags: , , , , , MOND - Modified Newtonian Dynamics, , , Weizmann Institute of Science   

    From Nautilus: “The Physicist Who Denies that Dark Matter Exists” 

    Nautilus

    Nautilus

    3.1.17
    Oded Carmeli

    1
    Mordehai Milgrom Credit: Weizmann Institute

    Maybe Newtonian physics doesn’t need dark matter to work, but Mordehai Milgrom instead.

    He is one of those dark matter people,” Mordehai Milgrom said about a colleague stopping by his office at the Weizmann Institute of Science. Milgrom introduced us, telling me that his friend is searching for evidence of dark matter in a project taking place just down the hall.

    “There are no ‘dark matter people’ and ‘MOND people,’” his colleague retorted.

    “I am ‘MOND people,’” Milgrom proudly proclaimed, referring to Modified Newtonian Dynamics, his theory that fixes Newtonian physics instead of postulating the existence of dark matter and dark energy—two things that, according to the standard model of cosmology, constitute 95.1% of the total mass-energy content of the universe.

    This friendly incident is indicative of (“Moti”) Milgrom’s calmly quixotic character. There is something almost misleading about the 70-year-old physicist wearing shorts in the hot Israeli summer, whose soft voice breaks whenever he gets excited. Nothing about his pleasant demeanor reveals that this man claims to be the third person to correct Newtonian physics: First Max Planck (with quantum theory), then Einstein (with relativity), now Milgrom.

    This year marks Milgrom’s 50th year at the Weizmann. I visited him there to learn more about how it feels to be a science maverick, what he appreciates about Thomas Kuhn’s The Structure of Scientific Revolutions, and why he thinks dark matter and dark energy don’t exist.

    What inspired you to dedicate your life to the motion of stars?

    I remember very vividly the way physics struck me. I was 16 and I thought: Here is a way to understand how things work, far beyond the understanding of my peers. I was drawn to the beauty of finding deeper reasons for events, to the aesthetics of discovering hidden symmetries. It wasn’t a long-term plan. It was a daily attraction. I simply loved physics, the same way other people love art or sports. I never dreamed of one day making a major discovery, like correcting Newton.

    I had a terrific physics teacher at school, but when you study textbook material, you’re studying done deals. You still don’t see the effort that goes into making breakthrough science, when things are unclear and advances are made intuitively and often go wrong. They don’t teach you that at school. They teach you that science always goes forward: You have a body of knowledge, and then someone discovers something and expands that body of knowledge. But it doesn’t really work that way. The progress of science is never linear.

    How did you get involved with the problem of dark matter?

    Toward the end of my Ph.D., the physics department here wanted to expand. So they asked three top Ph.D. students working on particle physics to choose a new field. We chose astrophysics, and the Weizmann Institute pulled some strings with institutions abroad so they would accept us as postdocs. And so I went to Cornell to fill my gaps in astrophysics.

    After a few years in high energy astrophysics, working on the physics of X-ray radiation in space, I decided to move to yet another field: The dynamics of galaxies. It was a few years after the first detailed measurements of the speed of stars orbiting spiral galaxies came in. And, well, there was a problem with the measurements.

    To understand this problem, one needs to wrap one’s head around some celestial rotations. Our planet orbits the sun, which, in turn, orbits the center of the Milky Way galaxy. Inside solar systems, the gravitational pull from the mass of the sun and the speed of the planets are in balance. By Newton’s laws, this is why Mercury, the innermost planet in our solar system, orbits the sun at over 100,000 miles per hour, while the outermost plant, Neptune, is crawling at just over 10,000 miles per hour.

    Now, you might assume that the same logic would apply to galaxies: The farther away the star is from the galaxy’s center, the slower it revolves around it; however, while at smaller radiuses the measurements were as predicted by Newtonian physics, farther stars proved to move much faster than predicted from the gravitational pull of the mass we see in these galaxies. The observed gap got a lot wider when, in the late 1970s, radio telescopes were able to detect and measure the cold gas clouds at the outskirts of galaxies. These clouds orbit the galactic center five times farther than the stars, and thus the anomaly grew to become a major scientific puzzle.

    One way to solve this puzzle is to simply add more matter. If there is too little visible mass at the center of galaxies to account for the speed of stars and gas, perhaps there is more matter than meets the eye, matter that we cannot see, dark matter.

    2
    MOND in the MakingMilgrom’s notes from 1981. On the left, each line represents the data from a separate galaxy. On the right is the MOND prediction, which is the line going through the data points.
    Mordehai Milgrom

    What made you first question the very existence of dark matter?

    What struck me was some regularity in the anomaly. The rotational velocities were not just larger than expected, they became constant with radius. Why? Sure, if there was dark matter, the speed of stars would be greater, but the rotation curves, meaning the rotational speed drawn as a function of the radius, could still go up and down depending on its distribution. But they didn’t. That really struck me as odd. So, in 1980, I went on my Sabbatical in the Institute for Advance Studies in Princeton with the following hunch: If the rotational speeds are constant, then perhaps we’re looking at a new law of nature. If Newtonian physics can’t predict the fixed curves, perhaps we should fix Newton, instead of making up a whole new class of matter just to fit our measurements.

    If you’re going to change the laws of nature that work so well in our own solar system, you need to find a property that differentiates solar systems from galaxies. So I made up a chart of different properties, such as size, mass, speed of rotation, etc. For each parameter, I put in the Earth, the solar system and some galaxies. For example, galaxies are bigger than solar systems, so perhaps Newton’s laws don’t work over large distances? But if this was the case, you would expect the rotation anomaly to grow bigger in bigger galaxies, while, in fact, it is not. So I crossed that one out and moved on to the next properties.

    I finally struck gold with acceleration: The pace at which the velocity of objects changes.

    We usually think of earthbound cars that accelerate in the same direction, but imagine a merry-go-round. You could be going in circles and still accelerate. Otherwise, you would simply fall off. The same goes for celestial merry-go-rounds. And it’s in acceleration that we find a big difference in scales, one that justifies modifying Newton: The normal acceleration for a star orbiting the center of a galaxy is about a hundred million times smaller than that of the Earth orbiting the sun.

    For those small accelerations, MOND introduces a new constant of nature, called a0. If you studied physics in high school, you probably remember Newton’s second law: force equals mass times acceleration, or F=ma. While this is a perfectly good tool when dealing with accelerations much greater than a0, such as those of the planets around our sun, I suggested that at significantly lower accelerations, lower even than that of our sun around the galactic center, force becomes proportional to the square of the acceleration, or F=ma2/a0.

    To put it in other words: According to Newton’s laws, the rotation speed of stars around galactic centers should decrease the farther the star is from the center of mass. If MOND is correct, it should reach a constant value, thus eliminating the need for dark matter.

    What did your colleagues at Princeton think about all this?

    I didn’t share these thoughts with my colleagues at Princeton. I was afraid to come across as, well, crazy. And then, in 1981, when I already had a clear idea of MOND, I didn’t want anyone to jump on my wagon, so to speak, which is even crazier when you think about it. Needless to say,” he laughs, “no one jumped on my wagon, even when I desperately wanted them to.

    Well, you were 35 and you proposed to fix Newton.

    Why not? What’s the big deal? If something doesn’t work, fix it. I wasn’t trying to be bold. I was very naïve at the time. I didn’t understand that scientists are just as swayed as other people by conventions and interests.

    Like Thomas Kuhn’s The Structure of Scientific Revolutions.

    I love that book. I read it several times. It showed me how my life’s story has happened to so many others scientists throughout history. Sure, it’s easy to make fun of people who once objected to what we now know is good science, but are we any different? Kuhn stresses that these objectors are usually good scientists with good reasons to object. It is just that the dissenters usually have a unique point of view of things that is not shared by most others. I laugh about it now, because MOND has made such progress, but there were times when I felt depressed and isolated.

    What’s it like being a science maverick?

    By and large, the last 35 years have been exciting and rewarding exactly because I have been advocating a maverick paradigm. I am a loner by nature, and despite the daunting and doubting times, I much prefer this to being carried with the general flow. I was quite confident in the basic validity of MOND from the very start, which helped me a lot in taking all this in stride, but there are two great advantages to the lingering opposition to MOND: Firstly, it gave me time to make more contributions to MOND than I would had the community jumped on the MOND wagon early on. Secondly, once MOND is accepted, the long and wide resistance to it will only have proven how nontrivial an idea it is.

    By the end of my sabbatical in Princeton, I had secretly written three papers introducing MOND to the world. Publishing them, however, was a whole different story. At first I sent my kernel paper to journals such as Nature and Astrophysical Journal Letters, and it got rejected almost off-hand. It took a long time until all three papers were published, side by side, in Astrophysical Journal.

    The first person to hear about MOND was my wife Yvonne. Frankly, tears come to my eyes when I say this. Yvonne is not a scientist, but she has been my greatest supporter.

    The first scientist to back MOND was another physics maverick: The late Professor Jacob Bekenstein, who was the first to suggest that black holes should have a well-defined entropy, later dubbed the Bekenstein-Hawking entropy. After I submitted the initial MOND trilogy, I sent the preprints to several astrophysicists, but Jacob was the first scientist I discussed MOND with. He was enthusiastic and encouraging from the very start.

    Slowly but surely, this tiny opposition to dark matter grew from just two physicists to several hundred proponents, or at least scientists who take MOND seriously. Dark matter is still the scientific consensus, but MOND is now a formidable opponent that proclaims the emperor has no clothes, that dark matter is our generation’s ether.

    So what happened? As far as dark matter is concerned, nothing really. A host of experiments searching for dark matter, including the Large Hadron Collider, many underground experiments and several space missions, have failed to directly observe its very existence. Meanwhile, MOND was able to accurately predict the rotation of more and more spiral galaxies—over 150 galaxies to date, to be precise.

    All of them? Some papers claim that MOND wasn’t able to predict the dynamics of certain galaxies.

    That’s true and it’s perfectly fine, because MOND’s predictions are based on measurements. Given the distribution of regular, visible matter alone, MOND can predict the dynamics of galaxies. But that prediction is based on our initial measurements. We measure the light coming in from a galaxy to calculate its mass, but we often don’t know the distance to that galaxy for sure, so we don’t know for certain just how massive that galaxy really is. And there are other variables, such as molecular gas, that we can’t observe at all. So yes, some galaxies don’t perfectly match MOND’s predictions, but all in all, it’s almost a miracle that we have enough data on galaxies to prove MOND right, over and over again.

    Your opponents say MOND’s greatest flaw is its incompatibility with relativistic physics.

    In 2004, Bekenstein proposed his TeVeS, or Relativistic Gravitational Theory for MOND. Since then, several different relativistic MOND formulations have been put forth, including one by me, called Bimetric MOND, or BIMOND.

    So, no, incorporating MOND into Einsteinian physics is no longer a challenge. I hear this statement still made, but only from people who parrot others, who themselves are not abreast with the developments of the last 10 years. There are several relativistic versions of MOND. What remains a challenge is demonstrating that MOND can account for the mass anomalies in cosmology.

    Another argument that cosmologists often make is that dark matter is needed not just for motion within galaxies, but on even larger scales. What does MOND have to say about that?

    According to the Big Bang theory, the universe began as a uniform singularity 13.8 billion years ago. And, just as in galaxies, observations made of the cosmic background radiation from the early universe suggest that the gravity of all the matter in the universe is simply not enough to form the different patterns we currently see, like galaxies and stars, in just 13.8 billion years. Once again, dark matter was called to the rescue: It does not emit radiation, but it does engage visible material with gravitation. And so, starting from the 1980s, the new cosmological dogma was that dark matter constituted a staggering 95 percent of all matter in the universe. That lasted, well, right until the bomb hit us in 1998.

    It turned out that the expansion of the universe is accelerating, not decelerating like all of us originally thought. Any form of genuine matter, dark or not, should have slowed down acceleration. And so a whole new type of entity was invented: Dark energy. Now the accepted cosmology is that the universe is made up of 70 percent dark energy, 25 percent dark matter, and 5 percent regular matter.

    But dark energy is just a quick fix, the same as dark matter is. And just as in galaxies, you can either invent a whole new type of energy and then spend years trying to understand its properties, or you can try fixing your theory.

    Among other things, MOND points to a very deep connection between structure and dynamics in galaxies and cosmology. This is not expected in accepted physics. Galaxies are tiny structures within the grand scale of the universe, and those structures can behave differently without contradicting the current cosmological consensus. However, MOND creates this connection, binding the two.

    This connection is surprising: For whatever reason, the MOND constant of a0 is close to the acceleration that characterizes the Universe itself. In fact, MOND’s constant equals the speed of light squared, divided by the radius of universe.

    So, indeed, to your question, the conundrum pointed to is valid at present. MOND doesn’t have a sufficient cosmology yet, but we’re working on it. And once we fully understand MOND, I believe we’ll also fully understand the expansion of the universe, and vice versa: A new cosmological theory would explain MOND. Wouldn’t that be amazing?

    What do you think about the proposed unified theories of physics, which merge MOND with quantum mechanics?

    These all hark back to my 1999 paper on ‘MOND as a vacuum effect’, where it was pointed out that the quantum vacuum in a universe such as ours may produce MOND behavior within galaxies, with the cosmological constant appearing in the guise of the MOND acceleration constant, a0. But I am greatly gratified to see these propositions put forth, especially because they are made by people outside the traditional MOND community. It is very important that researchers from other backgrounds become interested in MOND and bring new ideas to further our understanding of its origin.

    And what if you had a unified theory of physics that explains everything? What then?

    You know, I’m not a religious person, but I often think about our tiny blue dot, and the painstaking work we physicists do here. Who knows? Perhaps somewhere out there, in one of those galaxies I spent my life researching, there already is a known unified theory of physics, with a variation of MOND built into it. But then I think: So what? We still had fun doing the math. We still had the thrill of trying to wrap our heads around the universe, even if the universe never noticed it at all.

    See the full article here .

    Please help promote STEM in your local schools.

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 2:48 pm on January 30, 2017 Permalink | Reply
    Tags: , , , Dr. Miriam Eisenstein, GSK-3, Modeling of molecules on the computer, , Weizmann Institute of Science,   

    From Weizmann: Women in STEM – “Staff Scientist: Dr. Miriam Eisenstein” 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    30.01.2017
    No writer credit found

    1
    Name: Dr. Miriam Eisenstein
    Department: Chemical Research Support

    “The modeling of molecules on the computer,” says Dr. Miriam Eisenstein, Head of the Macromolecular Modeling Unit of the Weizmann Institute of Science’s Chemical Research Support Department, “is sometimes the only way to understand exactly how such complex molecules as proteins interact.”

    Eisenstein was one of the first to develop molecular docking methods while working with Prof. Ephraim Katzir – over two decades ago – and she has worked in collaboration with many groups at the Weizmann Institute.

    But even with all her experience, protein interactions can still surprise her. This was the case in a recent collaboration with the lab group of Prof. Hagit Eldar-Finkelman of Tel Aviv University, in research that was hailed as a promising new direction for finding treatments for Alzheimer’s disease. Eldar-Finkelman and her group were investigating an enzyme known as GSK-3, which affects the activity of various proteins by clipping a particular type of chemical tag, known as a phosphate group, onto them. GSK-3 thus performs quite a few crucial functions in the body, but it can also become overactive, and this extra activity has been implicated in a number of diseases, including diabetes and Alzheimer’s.

    The Tel Aviv group, explains Eisenstein, was exploring a new way of blocking, or at least damping down, the activity of this enzyme. GSK-3 uses ATP — a small, phosphate-containing molecule — in the chemical tagging process, transferring one of the ATP phosphate groups to a substrate. The ATP binding site on the enzyme is often targeted with ATP-like drug compounds that by themselves binding prevent the ATP from binding, thus blocking the enzyme’s activity. But such compounds are not discriminating enough, often blocking related enzymes in the process, which is an undesired side effect. This is why Eldar-Finkelman and her team looked for molecules that would compete with the substrate and occupy its binding cavity, so that the enzyme’s normal substrates cannot attach to GSK-3 and clip onto the phosphate groups.

    After identifying one molecule – a short piece of protein, or peptide – that substituted for GSK-3’s substrates in experiments, Eldar-Finkelman turned to Eisenstein to design peptides that would be better at competing with the substrate. At first Eisenstein computed model structures of the enzyme with an attached protein substrate and the enzyme with an attached peptide; she then characterized the way in which the enzyme binds either the substrate or the competing peptide. The model structures pinpointed the contacts, and these were verified experimentally by Eldar-Finkelman.

    This led to the next phase, a collaborative effort to introduce alterations to the peptide so as to improve its binding capabilities. One of the new peptides was predicted by Eisenstein to be a good substrate, and Eldar-Finkelman’s experiments showed that it indeed was. Once chemically tagged, the new peptide proved to be excellent at binding to GSK-3 – many times better than the original – and this was the surprise, because normally, once they are tagged, such substrates are repelled from the substrate-binding cavity and end up dissociating from the enzyme. Molecular modeling explained what was happening. After initially binding as a substrate and attaining a phosphate group, the peptide slid within the substrate-binding cavity, changing its conformation in the process, and attached tightly to a position normally occupied by the protein substrate.

    Experiments in Eldar-Finkelman’s group showed that this peptide is also active in vivo and, moreover, was able to reduce the symptoms of an Alzheimer-like condition in mice. The results of this research appeared in Science Signaling.

    “This experiment is a great example of the synergy between biologists and computer modelers,” says Eisenstein. “Hagit understands the function of this enzyme in the body, and she had this great insight on a possible way to control its actions. I am interested in the way that two proteins fit together and influence one another at the molecular and atomic levels, so I can provide the complementary insight.”

    “Molecular modeling is such a useful tool, it has enabled me to work with a great many groups and take part in a lot of interesting, exciting work, over the years,” she adds. “Computers have become much stronger in that time, but the basic, chemical principles of attraction and binding between complex molecules remain the same, and our work is as relevant as ever.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
  • richardmitnick 8:50 am on January 24, 2017 Permalink | Reply
    Tags: , , Endoplasmic reticulum, , Snd2, SRP pathway, Weizmann Institute of Science   

    From Weizman: “Outward-Bound Proteins Have a Third Way” 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    22.01.2017
    No writer credit found

    A newly discovered “shuttle” for proteins is a “safety net” for vital communication between cells.

    1
    Snd2 was tagged with a green fluorescent protein, and the endoplasmic reticulum was marked with a red fluorescent protein. The overlap between the green and red microscopy signals indicates that the newly discovered Snd2 is a receptor on the endoplasmic reticulum membrane. No image credit.

    The cells in our bodies must constantly communicate with one another. For many, it is a matter of survival; for others, it is the way they keep our bodies healthy and functioning efficiently. Communications are carried out by proteins – both the numerous proteins that are situated on the cells’ outer membranes to receive the messages and the messengers themselves, which are secreted to the outside of the cell. For most of these proteins, getting to the outside of the cell involves passage through an organelle called the endoplasmic reticulum. This first entails getting across the membrane of this organelle, to which the proteins are targeted, with the help of a special “shuttle” that conducts them to a sort of “transit area,” checking them first to see if they have the proper “passports.”

    How many different shuttles are needed to move all these proteins – in effect, around 30% of all the proteins in each cell? Previous studies of the past few decades have identified two – sort of couriers, like FedEx or DHL for proteins. Now, a new study [Nature], conducted in the lab of Prof. Maya Schuldiner of the Institute’s Molecular Genetics Department, has uncovered a third shuttle, and raised the possibility that more might be awaiting discovery.

    2
    (l-r) Naama Aviram and Prof. Maya Schuldiner describe a ‘safety net’ for communication proteins. No image credit.

    The study was led by research student Naama Aviram, in collaboration with the labs of Prof. Richard Zimmerman of Saarland University, Germany, Prof. Blanche Schwappach of Göttingen University, also inGermany, and Prof. Jonathan Weissman of the University of California, San Francisco. “The first pathway for transferring proteins into the endoplasmic reticulum was discovered in the 1980s,” says Schuldiner. “Scientists found that this shuttle, called SRP, identifies the protein to be transported by reading a tag that is a sort of ‘passport’.”

    But this finding was not the whole story: Although many proteins use the SRP pathway to get to the endoplasmic reticulum membrane, this shuttle system seemed to have trouble identifying other outward-bound proteins. The reason eventually became clear: SRP easily identifies the tag when it is situated at one end of the protein, but has a hard time with tags at the other end. “This suggested that there was another pathway to catch the proteins that SRP misses,” says Schuldiner. “We identified that pathway in 2008 and named it GET.”

    3
    The “shuttles” that lead proteins to the endoplasmic reticulum: the two previously known SRP and GET pathways, together with the newly discovered SND pathway, each caters for proteins with a different position of their “passports”. No image credit.

    But even with two shuttle services, the scientists noted there were still proteins that were not easily recognized by the pathways. “These are proteins that, if they are not efficiently transported to the endoplasmic reticulum, the cell dies. So we undertook a search for yet another pathway,” says Aviram.

    The team began their experiments in yeast cells, whose basic functions are nearly identical to those of human cells, and then tested their results in human cells. To begin, the researchers identified proteins that need to pass through the endoplasmic reticulum transit area, but do not receive assistance from either known pathway.

    Then, using the advanced robotic system in Schuldiner’s lab, they systematically looked at the ability of a protein to reach the endoplasmic reticulum membrane in the absence of each gene in the yeast cell, finding three that appeared to be necessary to the process of transporting these particular “problematic” proteins. When these genes were missing, the researchers observed accumulations of protein within the cell – proteins that had not managed to reach their destination outside of it.

    The three genes, which the team called SND1, SND2 and SND3, work together; one on the ribosome (the cell’s protein-manufacturing complex) and the other two at the “gates” of the endoplasmic reticulum.

    Together with the Weissman lab in San Francisco, the scientists revealed that this third pathway is active when the “passport” is closer to the center of the protein – the region the other two pathways have a hard time reading. “The new pathway functions as a ‘safety net’ for crucial proteins that may need to catch the next shuttle, but have their tags in inconvenient places,” says Schuldiner.

    Together with the Zimmerman lab, the researchers then asked whether this was occurring in a similar way in human cells. The scientists silenced the human SND2 gene – which they found has been conserved throughout evolution – and showed that here, too, the passage into the endoplasmic reticulum was defective, suggesting that this third pathway is at work in human cells as it is in yeast.

    “Many diseases, for example diabetes, involve disruption to intercellular communications,” says Schuldiner. “And we don’t always know just where the message goes astray. Maybe, in the future, understanding this pathway might help us figure out how to treat disease and save lives.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
  • richardmitnick 11:20 am on December 4, 2016 Permalink | Reply
    Tags: , , , , Weizmann Institute of Science   

    From Weizmann: “When Cells Are Fit” 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    07.11.2016 [I guess this has just ben in hiding.]
    No writer credit found

    How do the expression levels of numerous proteins affect a cell’s fitness?

    Tracking protein activity levels in a cell is essential to the study of such diseases as cancer which, alongside changes in the genes, involves changes in the activity levels of numerous proteins. However, deducing function, fitness and cellular well-being from the growing number of protein level measurements is still a major challenge. For example, is a two-fold – or 100-fold – range in activity for a particular protein tolerable over the population, or does it herald differences in the way that the cells carry out their tasks? Charting this connection could transform the way we diagnose, monitor and treat patients.

    1
    (l-r) Maya Lotan-Pompan, Leeat Yankielowicz Keren and Prof. Eran Segal can now look at multiple protein expression levels at once

    “Most experiments examining ranging protein activity levels have, until now, focused on single proteins. What we did was to develop a way to systematically vary activity levels for hundreds of different proteins – all in a single experiment – and accurately measure how this affects the function of the cells,” says Leeat Yankielowicz Keren, a research student in the group of Prof. Eran Segal of the Computer Science and Applied Mathematics, and Molecular Cell Biology Departments at the Weizmann Institute of Science.

    The basic idea of the experiment in Segal’s lab was to create a competition in which common bakers’ yeast cells are pitted against one another. Each cell was nearly identical to its neighbors, except for a tweak to the activity level of one of its proteins. Thousands of these genetically engineered yeast cells were grown together in lab dishes; the “winners” were those in which expression levels boosted their fitness, basically enabling the yeast to eat more, grow and divide faster.

    Segal and his group developed a high-throughput genetic engineering technique that enabled them to manipulate the activity levels of different protein levels within thousands of cells simultaneously, precisely controlling, for each, the amounts of one particular protein. With 130 different activity levels – the highest 500 times the lowest – attached to 81 different protein-encoding sequences, the researchers created something like 10,000 different variations on the basic yeast cell, assigning each a “barcode” for convenient identification. With a combination of DNA sequencing techniques and an algorithm they created to reconstruct the growth rates of the various yeast cells, the team was then able to accurately map the connections between protein levels and the fitness of the cell.

    The competition took place in two different “arenas.” In one, the yeast were fed the glucose sugar they prefer; in the second, they were fed a different kind of sugar, galactose. The team found that when the competition took place on the kind of sugar it prefers, the original, untouched version of the yeast cell was the overall winner – testimony to the efficiency of evolution. But on the second kind of sugar, others came out on top. These results showed that around 20% of the yeast’s natural protein activity levels are too low or too high for growing on this sugar. This could be relevant to biotechnology: The second sugar is cheaply and abundantly found in seaweed, and the yeast break it down into ethanol, which can be burned in place of fossil fuels. The study suggests that genetically engineering yeast to alter some of these protein levels could significantly increase the efficiency of this process.

    Mapping all the activity patterns together enabled the group to begin to see patterns in the chaos. Similar activity patterns, for example, pointed to proteins that work together. Further analysis even revealed the “math” that cells use to produce these proteins in the right ratios, for example, for the construction of complexes that require exact proportions of their various proteins.

    Some of the proteins appeared to operate in a very narrow range – levels even a bit below or above this range drastically affected the fitness of the yeast. Others seemed to be much more flexible – a little or a lot did not affect the cell’s fitness, at least for the particular growing conditions. Those showing the larger ranges in the fitness competition turned out to be proteins that ordinarily vary widely from cell to cell in the natural yeast population. These findings suggest that understanding this flexibility can shed light on how activity levels are selected in evolution.

    2
    Gene fitness profiles are different when yeast are grown on a sugar they normally prefer less

    For Segal and his team, the future goal is to create similar maps for protein activity levels in human cells. Such maps could form the basis of future diagnostic techniques that would be much more refined and precise than those of today, based on blood tests that already exist or can easily be developed. They might reveal the effects of diet or medications; and they could provide early diagnosis of cancer. Keren: “We want to eventually create a ‘chart’ that doctors can use to know which protein levels to check, and what levels should, ideally, be appearing in order to prevent disease.”

    Also participating in this study were Maya Lotan-Pompan and Dr. Adina Weinberger of Prof. Segal’s group, Dr. Jean Hausser and Prof. Uri Alon of the department of Molecular Cell Biology and Prof. Ron Milo of the department of Plant and Environmental Sciences.

    Science paper:
    Massively Parallel Interrogation of the Effects of Gene Expression Levels on Fitness, Cell

    See the full article here .

    Please help promote STEM in your local schools.

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
  • richardmitnick 10:42 am on September 19, 2016 Permalink | Reply
    Tags: , , , , Weizmann Institute of Science   

    From Weizmann: “Israeli Instrument Bound for Jupiter” 

    Weizmann Institute of Science logo

    Weizmann Institute of Science

    07.01.2016 [This just appeared in social media.]
    No writer credit found

    Sometime in the year 2030, if all goes according to plan, some dozen groups around the world will begin receiving unique data streams sent from just above the planet Jupiter. Their instruments, which will include a device designed and constructed in Israel, will arrive there aboard the JUICE (JUpiter ICy satellite Explorer) spacecraft, a mission planned by the European Space Agency (ESA) to investigate the properties of the Solar System’s largest planet and several of its moons.

    ESA JUICE
    esa-juice-spacecraft
    ESA JUICE

    Among other things, the research groups participating in JUICE hope to discover whether the conditions for life exist anywhere in the vicinity of the planet.

    “This is the first time that an Israeli-built device will be carried beyond the Earth’s orbit,” says Dr. Yohai Kaspi of the Weizmann Institute’s Earth and Planetary Sciences Department, who is the principal investigator on this effort. The project, conducted in collaboration with an Italian team from the University of Rome, is called 3GM (Gravity & Geophysics of Jupiter and Galilean Moons).

    The Israeli contribution to the project is an atomic clock that will measure tiny vacillations in a radio beam provided by the Italian team. This clock must be so accurate it would lose less than a second in 100,000 years, so Kaspi has turned to the Israeli firm AccuBeat, which manufactures clocks that are used in high-tech aircraft, among other things. Its engineers, together with Kaspi and his team, including Dr. Eli Galanti and Dr. Marzia Parisi, have spent the last two years in research and development to design a device that should not only meet the strict demands of the experiment but survive the eight-year trip and function in the conditions of space. Their design was recently approved for flight by the European Space Agency. Israel’s Ministry of Science and Technology will fund the research, building and assembly of the device.

    For around two and a half years as JUICE orbits Jupiter, the 3GM team will investigate the planet’s atmosphere by intercepting radio waves traveling through the gas, timing them and measuring the angle at which the waves are deflected. This will enable them to decipher the atmosphere’s makeup.

    During flybys of three of the planet’s moons – Europa, Ganymede and Callisto – the 3GM instruments will help search for tides. Researchers observing these moons have noted fluctuations in the gravity of these moons, suggesting the large mass of Jupiter is creating tides in liquid oceans beneath their hard, icy exteriors. By measuring the variations in gravity, the researchers hope to learn how large these oceans are, what they are made of, and even whether their conditions might harbor life.

    The JUICE teams are preparing for a launch in 2022. That gives them three years to get the various instruments ready and another three to assemble and test the craft. In the long wait – eight years – from launch to arrival, Kaspi intends to work on building theoretical models that can be tested against the data they will receive from their instruments.

    See the full article here .

    Please help promote STEM in your local schools.

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    Weizmann Institute Campus

    The Weizmann Institute of Science is one of the world’s leading multidisciplinary research institutions. Hundreds of scientists, laboratory technicians and research students working on its lushly landscaped campus embark daily on fascinating journeys into the unknown, seeking to improve our understanding of nature and our place within it.

    Guiding these scientists is the spirit of inquiry so characteristic of the human race. It is this spirit that propelled humans upward along the evolutionary ladder, helping them reach their utmost heights. It prompted humankind to pursue agriculture, learn to build lodgings, invent writing, harness electricity to power emerging technologies, observe distant galaxies, design drugs to combat various diseases, develop new materials and decipher the genetic code embedded in all the plants and animals on Earth.

    The quest to maintain this increasing momentum compels Weizmann Institute scientists to seek out places that have not yet been reached by the human mind. What awaits us in these places? No one has the answer to this question. But one thing is certain – the journey fired by curiosity will lead onward to a better future.

     
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