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  • richardmitnick 12:24 pm on October 21, 2021 Permalink | Reply
    Tags: "Need for Larger Space Telescope Inspires Lightweight Flexible Holographic Lens", , , , , Rensselaer Polytechnic Institute (US), The holographic optical element is a refined version of a Fresnel lens., The new method allows the designers to either focus light onto a single point or disperse it into its constituent colors.   

    From Rensselaer Polytechnic Institute (US) : “Need for Larger Space Telescope Inspires Lightweight Flexible Holographic Lens” 

    From Rensselaer Polytechnic Institute (US)

    October 21, 2021
    Mary L. Martialay

    1
    New technique produces lens for focused image or spectrum.

    Inspired by a concept for discovering exoplanets with a giant space telescope, a team of researchers is developing holographic lenses that render visible and infrared starlight into either a focused image or a spectrum. The experimental method, detailed in an article appearing today in Nature Scientific Reports, could be used to create a lightweight flexible lens, many meters in diameter, that could be rolled for launch and unfurled in space.

    “We use two spherical waves of light to produce the hologram, which gives us fine control over the diffractive grating recorded on the film, and the effect it has on light — either separating light with super sensitivity, or focusing light with high resolution,” said Mei-Li Hsieh, a visiting researcher at Rensselaer Polytechnic Institute and an expert in optics and photonics who established a mathematical solution to govern the output of the hologram. “We believe this model could be useful in applications that require extremely high spectral resolution spectroscopy, such as analysis of exoplanets.”

    Hsieh, who also holds a faculty position at National Yang Ming Chiao Tung University[國立陽明交通大學](TW) in Taiwain, along with Rensselaer physicists Shawn-Yu Lin and Heidi Jo Newberg, worked with Thomas D. Ditto, an artist and inventor who conceived the idea of an optical space telescope freed of conventional, and heavy, glass mirrors and lenses. Ditto first worked at Rensselaer in the 1970s and is currently a visiting researcher in astrophysics.

    Telescopes that must be launched into space (to benefit from a view unimpeded by Earth’s atmosphere) are limited by the weight and bulk of glass mirrors used to focus light, which can realistically span only a few meters in diameter. By contrast, the lightweight flexible holographic lens — more properly called a “holographic optical element” — used to focus light could be dozens of meters across. Such an instrument could be used to directly observe an exoplanet, a leap over current methods that detect exoplanets based on their effect on light coming from the star they orbit, said Newberg, a Rensselaer professor of physics, applied physics, and astronomy.

    “To find Earth 2.0, we really want to see exoplanets by direct imaging — we need to be able to look at the star and see the planet separate from the star. And for that, we need high resolution and a really big telescope,” said Newberg, an astrophysicist and expert in galactic structure.

    The holographic optical element is a refined version of a Fresnel lens, a category of lenses that use concentric rings of prisms arrayed in a flat plane to mimic the focusing ability of a curved lens without the bulk. The concept of the Fresnel lens — which was developed for use in lighthouses —dates to the 19th century, with modern-day Fresnel lenses of glass or plastic found in automobile lamps, micro-optics, and camera screens.

    But while Fresnel holographic optical elements — created by exposing a light-sensitive plastic film to two sources of light at different distances from the film — are not uncommon, existing methods were limited to lenses that could only focus light, rather than separating it into its constituent colors.

    The new method allows the designers to either focus light onto a single point or disperse it into its constituent colors, producing a spectrum of pure colors, said Lin, corresponding author and a Rensselaer professor of physics, applied physics, and astronomy. The method uses two sources of light, positioned very close to one another, which create concentric waves of light that — as they travel toward the film — either build or cancel each other out. This pattern of convergence or interference can be tuned based on the formulas Hsieh developed. It is printed, or “recorded,” onto the film as a holographic image and, depending on how the image is structured, light passing through the holographic optical element is either focused or stretched.

    “We wanted to stretch the light, so that we could separate it into different wavelengths. Any Fresnel lens will stretch the light a little, but not enough,” said Lin, an expert in photonic crystals and nano-photonics. “With our method, we can have super resolution on one end, or super sensitive — with each color separated. When the light is stretched like that, the color is very good, as pure and as vivid as you can get.”

    Hsieh, Newberg, Lin, and Ditto were joined in the research by Yi-Wen Lee and Shiuan-Huei Lin of National Yang Ming Chiao Tung University.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded in 1824, Rensselaer Polytechnic Institute (US) is America’s first technological research university. Rensselaer encompasses five schools, 32 research centers, more than 145 academic programs, and a dynamic community made up of more than 7,900 students and more than 100,000 living alumni. Rensselaer faculty and alumni include more than 145 National Academy members, six members of the National Inventors Hall of Fame, six National Medal of Technology winners, five National Medal of Science winners, and a Nobel Prize winner in Physics. With nearly 200 years of experience advancing scientific and technological knowledge, Rensselaer remains focused on addressing global challenges with a spirit of ingenuity and collaboration.

    With 7,900 students and more than 100,000 living alumni, Rensselaer is addressing the global challenges facing the 21st century—to change lives, to advance society, and to change the world.

    RPI is organized into six main schools which contain 37 departments, with emphasis on science and technology It is recognized for its degree programs in engineering, computing, business and management, information technology, the sciences, design, and liberal arts. As of 2017, RPI’s faculty and alumni include six members of the National Inventors Hall of Fame (US), six National Medal of Technology winners, five National Medal of Science winners, eight Fulbright Scholarship recipients, and a Nobel Prize winner in Physics; in addition, 86 faculty or alumni are members of the National Academy of Engineering (US), 17 of the National Academy of Sciences (US), 25 of the American Academy of Arts and Sciences (US), eight of the National Academy of Medicine (US), one of the National Academy of Public Administration (US), and nine of the National Academy of Inventors (US).

    From renewable energy to cybersecurity, from biotechnology to materials science, from big data to nanotechnology, the world needs problem solvers—exactly the kind of talent Rensselaer produces—to address the urgent issues of today and the emerging issues of tomorrow.

    Research and development

    Rensselaer is classified among “R1: Doctoral Universities – Very High Research Activity”. Rensselaer has established six areas of research as institute priorities: biotechnology, energy and the environment, nanotechnology, computation and information technology, and media and the arts. Research is organized under the Office of the Vice President for Research. In 2018, Rensselaer operated 34 research centers and maintained annual sponsored research expenditures of $100.8 million.
    Center for Biotechnology and Interdisciplinary Studies

    One of the most recent of Rensselaer’s research centers is the Center for Biotechnology and Interdisciplinary Studies, a 218,000 square-foot research facility and a national pacesetter for fundamental and applied research in biotechnology. The primary target of the research center is biologics, a research priority based on data-driven understanding of proteomics, protein regulation, and gene regulation. It involves using biocatalysis and synthetic biology tools to block or supplement the actions of specific cells or proteins in the immune system. Over the past decade, CBIS has produced over 2,000 peer-reviewed publications with over 30,000 citations and currently employs over 200 scientists and engineers. The center is also used primarily to train undergraduate and graduate students, with over 1,000 undergraduates and 200 doctoral students trained.

    The center also has numerous academic and industry partners including the Icahn School of Medicine at Mount Sinai. These partnerships have resulted in numerous advances over the last decade through new commercial developments in diagnostics, therapeutics, medical devices, and regenerative medicine which are a direct result of research at the center. Examples of advancements include the creation of synthetic heparin, antimicrobial coatings, detoxification chemotherapy, on-demand bio-medicine, implantable sensors, and 3D cellular array chips.

    Rensselaer also hosts the Tetherless World Constellation (US), a multidisciplinary research institution focused on theories, methods, and applications of the World Wide Web. Research is carried out in three inter-connected themes: Future Web, Semantic Foundations and Xinformatics. At Rensselaer, a constellation is a multidisciplinary team composed of senior and junior faculty members, research scientists, and postdoctoral, graduate, and undergraduate students. Faculty alumni of TWC includes Heng Ji (Natural Language Processing). In 2016, the Constellation received a one million dollar grant from the Bill & Melinda Gates Foundation (US) for continuing work on a novel data visualization platform that will harness and accelerate the analysis of vast amounts of data for the foundation’s Healthy Birth, Growth, and Development Knowledge Integration initiative.

    In conjunction with the constellation, Rensselaer operates the Center for Computational Innovations which is the result of a $100 million collaboration between Rensselaer, IBM, and New York State to further nanotechnology innovations. The center’s main focus is on reducing the cost associated with the development of nanoscale materials and devices, such as used in the semiconductor industry. The university also utilizes the center for interdisciplinary research in biotechnology, medicine, energy, and other fields. Rensselaer additionally operates a nuclear reactor and testing facility – the only university-run reactor in New York State – as well as the Gaerttner Linear Accelerator, which is currently being upgraded under a $9.44 million grant from the Department of Energy (US).

     
  • richardmitnick 11:42 am on June 3, 2021 Permalink | Reply
    Tags: "World’s Lakes Losing Oxygen Rapidly as Planet Warms", , , , , , Rensselaer Polytechnic Institute (US)   

    From Rensselaer Polytechnic Institute (US) : “World’s Lakes Losing Oxygen Rapidly as Planet Warms” 

    From Rensselaer Polytechnic Institute (US)

    June 2, 2021
    Mary L. Martialay

    Changes threaten biodiversity and drinking water quality.

    1
    Credit: Gretchen Hansen, University of Minnesota (US)

    Oxygen levels in the world’s temperate freshwater lakes are declining rapidly — faster than in the oceans — a trend driven largely by climate change that threatens freshwater biodiversity and drinking water quality.

    Research published today in Nature found that oxygen levels in surveyed lakes across the temperate zone have declined 5.5% at the surface and 18.6% in deep waters since 1980. Meanwhile, in a large subset of mostly nutrient-polluted lakes, surface oxygen levels increased as water temperatures crossed a threshold favoring cyanobacteria, which can create toxins when they flourish in the form of harmful algal blooms.

    “All complex life depends on oxygen. It’s the support system for aquatic food webs. And when you start losing oxygen, you have the potential to lose species,” said Kevin Rose, author and professor at Rensselaer Polytechnic Institute. “Lakes are losing oxygen 2.75-9.3 times faster than the oceans, a decline that will have impacts throughout the ecosystem.”

    Researchers analyzed a combined total of over 45,000 dissolved oxygen and temperature profiles collected since 1941 from nearly 400 lakes around the globe. Most long-term records were collected in the temperate zone, which spans 23 to 66 degrees north and south latitude. In addition to biodiversity, the concentration of dissolved oxygen in aquatic ecosystems influences greenhouse gas emissions, nutrient biogeochemistry, and ultimately, human health.

    Although lakes make up only about 3% of Earth’s land surface, they contain a disproportionate concentration of the planet’s biodiversity. Lead author Stephen F. Jane, who completed his Ph.D. with Rose, said the changes are concerning both for their potential impact on freshwater ecosystems and for what they suggest about environmental change in general.

    “Lakes are indicators or ‘sentinels’ of environmental change and potential threats to the environment because they respond to signals from the surrounding landscape and atmosphere. We found that these disproportionally more biodiverse systems are changing rapidly, indicating the extent to which ongoing atmospheric changes have already impacted ecosystems,” Jane said.


    World’s Lakes Losing Oxygen Rapidly as Planet Warms.

    Although widespread losses in dissolved oxygen across the studied lakes are linked to climate change, the path between warming climate and changing freshwater oxygen levels is driven by different mechanisms between surface and deep waters.

    Deoxygenation of surface waters was mostly driven by the most direct path: physics. As surface water temperatures increased by .38 degrees Centigrade per decade, surface water dissolved oxygen concentrations declined by .11 milligrams per liter per decade.

    “Oxygen saturation, or the amount of oxygen that water can hold, goes down as temperatures go up. That’s a known physical relationship and it explains most of the trend in surface oxygen that we see,” said Rose.

    However, some lakes experienced simultaneously increasing dissolved oxygen concentrations and warming temperatures. These lakes tended to be more polluted with nutrient-rich runoff from agricultural and developed watersheds and have high chlorophyll concentrations. Although the study did not include phytoplankton taxonomic measurements, warm temperatures and elevated nutrient content favor cyanobacteria blooms, whose photosynthesis is known to cause dissolved oxygen supersaturation in surface waters.

    “The fact that we’re seeing increasing dissolved oxygen in those types of lakes is potentially an indicator of widespread increases in algal blooms, some of which produce toxins and are harmful. Absent taxonomic data, however, we can’t say that definitively, but nothing else we’re aware of can explain this pattern,” Rose said.

    The loss of oxygen in deeper waters, where water temperatures have remained largely stable, follows a more complex path most likely tied to increasing surface water temperatures and a longer warm period each year. Warming surface waters combined with stable deep-water temperatures means that the difference in density between these layers, known as “stratification,” is increasing. The stronger this stratification, the less likely mixing is to occur between layers. The result is that oxygen in deep waters is less likely to get replenished during the warm stratified season, as oxygenation usually comes from processes that occur near the water surface.

    “The increase in stratification makes the mixing or renewal of oxygen from the atmosphere to deep waters more difficult and less frequent, and deep-water dissolved oxygen drops as a result,” said Rose. Water clarity losses were also associated with deep-water dissolved oxygen losses in some lakes. However, there was no overarching decline in clarity across lakes.

    Oxygen concentrations regulate many other characteristics of water quality. When oxygen levels decline, bacteria that thrive in environments without oxygen, such as those that produce the powerful greenhouse gas methane, begin to proliferate. This suggests the potential that lakes are releasing increased amounts of methane to the atmosphere as a result of oxygen loss. Additionally, sediments release more phosphorous under low oxygen conditions, adding nutrients to already stressed waters.

    “Ongoing research has shown that oxygen levels are declining rapidly in the world’s oceans. This study now proves that the problem is even more severe in fresh waters, threatening our drinking water supplies and the delicate balance that enables complex freshwater ecosystems to thrive,” said Curt Breneman, dean of the School of Science. “We hope this finding brings greater urgency to efforts to address the progressively detrimental effects of climate change.”

    “Widespread deoxygenation of temperate lakes” was published with support from the National Science Foundation. Rose and Jane were joined by dozens of collaborators in GLEON, the Global Lake Ecological Observatory Network, and based in universities, environmental consulting firms, and government agencies around the world.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded in 1824, Rensselaer Polytechnic Institute (US) is America’s first technological research university.

    With 7,900 students and more than 100,000 living alumni, Rensselaer is addressing the global challenges facing the 21st century—to change lives, to advance society, and to change the world.

    RPI is organized into six main schools which contain 37 departments, with emphasis on science and technology It is recognized for its degree programs in engineering, computing, business and management, information technology, the sciences, design, and liberal arts. As of 2017, RPI’s faculty and alumni include six members of the National Inventors Hall of Fame (US), six National Medal of Technology winners, five National Medal of Science winners, eight Fulbright Scholarship recipients, and a Nobel Prize winner in Physics; in addition, 86 faculty or alumni are members of the National Academy of Engineering (US), 17 of the National Academy of Sciences (US), 25 of the American Academy of Arts and Sciences (US), eight of the National Academy of Medicine (US), one of the National Academy of Public Administration (US), and nine of the National Academy of Inventors (US).

    From renewable energy to cybersecurity, from biotechnology to materials science, from big data to nanotechnology, the world needs problem solvers—exactly the kind of talent Rensselaer produces—to address the urgent issues of today and the emerging issues of tomorrow.

    Research and development

    Rensselaer is classified among “R1: Doctoral Universities – Very High Research Activity”. Rensselaer has established six areas of research as institute priorities: biotechnology, energy and the environment, nanotechnology, computation and information technology, and media and the arts. Research is organized under the Office of the Vice President for Research. In 2018, Rensselaer operated 34 research centers and maintained annual sponsored research expenditures of $100.8 million.
    Center for Biotechnology and Interdisciplinary Studies

    One of the most recent of Rensselaer’s research centers is the Center for Biotechnology and Interdisciplinary Studies, a 218,000 square-foot research facility and a national pacesetter for fundamental and applied research in biotechnology. The primary target of the research center is biologics, a research priority based on data-driven understanding of proteomics, protein regulation, and gene regulation. It involves using biocatalysis and synthetic biology tools to block or supplement the actions of specific cells or proteins in the immune system. Over the past decade, CBIS has produced over 2,000 peer-reviewed publications with over 30,000 citations and currently employs over 200 scientists and engineers. The center is also used primarily to train undergraduate and graduate students, with over 1,000 undergraduates and 200 doctoral students trained.

    The center also has numerous academic and industry partners including the Icahn School of Medicine at Mount Sinai. These partnerships have resulted in numerous advances over the last decade through new commercial developments in diagnostics, therapeutics, medical devices, and regenerative medicine which are a direct result of research at the center. Examples of advancements include the creation of synthetic heparin, antimicrobial coatings, detoxification chemotherapy, on-demand bio-medicine, implantable sensors, and 3D cellular array chips.

    Rensselaer also hosts the Tetherless World Constellation (US), a multidisciplinary research institution focused on theories, methods, and applications of the World Wide Web. Research is carried out in three inter-connected themes: Future Web, Semantic Foundations and Xinformatics. At Rensselaer, a constellation is a multidisciplinary team composed of senior and junior faculty members, research scientists, and postdoctoral, graduate, and undergraduate students. Faculty alumni of TWC includes Heng Ji (Natural Language Processing). In 2016, the Constellation received a one million dollar grant from the Bill & Melinda Gates Foundation (US) for continuing work on a novel data visualization platform that will harness and accelerate the analysis of vast amounts of data for the foundation’s Healthy Birth, Growth, and Development Knowledge Integration initiative.

    In conjunction with the constellation, Rensselaer operates the Center for Computational Innovations which is the result of a $100 million collaboration between Rensselaer, IBM, and New York State to further nanotechnology innovations. The center’s main focus is on reducing the cost associated with the development of nanoscale materials and devices, such as used in the semiconductor industry. The university also utilizes the center for interdisciplinary research in biotechnology, medicine, energy, and other fields. Rensselaer additionally operates a nuclear reactor and testing facility – the only university-run reactor in New York State – as well as the Gaerttner Linear Accelerator, which is currently being upgraded under a $9.44 million grant from the Department of Energy (US).

     
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