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42,991,435 | https://en.wikipedia.org/wiki/Two-dimensional%20flow | In fluid mechanics, a two-dimensional flow is a form of fluid flow where the flow velocity at every point is parallel to a fixed plane. The velocity at any point on a given normal to that fixed plane should be constant.
Flow velocity in two dimensional flows
Flow velocity in Cartesian co-ordinates
Considering a two dimensional flow in the plane, the flow velocity at any point at time can be expressed as –
Velocity in cylindrical co-ordinates
Considering a two dimensional flow in the plane, the flow velocity at a point at a time can be expressed as –
Vorticity in two dimensional flows
Vorticity in Cartesian co-ordinates
Vorticity in two dimensional flows in the plane can be expressed as –
Vorticity in cylindrical co-ordinates
Vorticity in two dimensional flows in the plane can be expressed as –
Two dimensional sources and sinks
Line/point source
A line source is a line from which fluid appears and flows away on planes perpendicular to the line. When we consider 2-D flows on the perpendicular plane, a line source appears as a point source.
By symmetry, we can assume that the fluid flows radially outward from the source.
The strength of a source can be given by the volume flow rate that it generates.
Line/point sink
Similar to a line source, a line sink is a line which absorbs fluid flowing towards it, from planes perpendicular to it. When we consider 2-D flows on the perpendicular plane, it appears as a point sink.
By symmetry, we assume the fluid flows radially inwards towards the sink.
The strength of a sink is given by the volume flow rate of the fluid it absorbs.
Types of two-dimensional flows
Uniform source flow
A radially symmetrical flow field directed outwards from a common point is called a source flow. The central common point is the line source described above. Fluid is supplied at a constant rate from the source. As the fluid flows outward, the area of flow increases. As a result, to satisfy continuity equation, the velocity decreases and the streamlines spread out. The velocity at all points at a given distance from the source is the same.
The velocity of fluid flow can be given as -
We can derive the relation between flow rate and velocity of the flow. Consider a cylinder of unit height, coaxial with the source. The rate at which the source emits fluid should be equal to the rate at which fluid flows out of the surface of the cylinder.
The stream function associated with source flow is –
The steady flow from a point source is irrotational, and can be derived from velocity potential. The velocity potential is given by –
Uniform sink flow
Sink flow is the opposite of source flow. The streamlines are radial, directed inwards to the line source. As we get closer to the sink, area of flow decreases. In order to satisfy the continuity equation, the streamlines get bunched closer and the velocity increases as we get closer to the source. As with source flow, the velocity at all points equidistant from the sink is equal.
The velocity of the flow around the sink can be given by –
The stream function associated with sink flow is –
The flow around a line sink is irrotational and can be derived from velocity potential. The velocity potential around a sink can be given by –
Irrotational vortex
A vortex is a region where the fluid flows around an imaginary axis.
For an irrotational vortex, the flow at every point is such that a small particle placed there undergoes pure translation and does not rotate.
Velocity varies inversely with radius in this case. Velocity will tend to at that is the reason for center being a singular point. The velocity is mathematically expressed as –
Since the fluid flows around an axis,
The stream function for irrotational vortices is given by –
While the velocity potential is expressed as –
For the closed curve enclosing origin, circulation (line integral of velocity field) and for any other closed curves,
Doublet
A doublet can be thought of as a combination of a source and a sink of equal strengths kept at an infinitesimally small distance apart. Thus the streamlines can be seen to start and end at the same point.
The strength of a doublet made by a source and sink of strength kept a distance is given by –
The velocity of fluid flow can be expressed as –
The equations and the plot are for the limiting condition of
The concept of a doublet is very similar to that of electric dipoles and magnetic dipoles in electrodynamics.
References
External links
Two-dimensional sources and sinks
Flow regimes
Fluid dynamics
Planes (geometry) | Two-dimensional flow | [
"Chemistry",
"Mathematics",
"Engineering"
] | 950 | [
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"Mathematical objects",
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42,991,619 | https://en.wikipedia.org/wiki/National%20Anti-Bullying%20Centre | The National Anti-Bullying Research and Resource Centre (ABC) is a research and resource facility at Dublin City University, Ireland. The Centre is normally referred to as the Anti-Bullying Centre or ABC.
A centre dedicated to the study of bullying behaviour had previously existed at Trinity College Dublin where it was founded in 1996 by Professor Mona O'Moore at the School of Education, Trinity College Dublin. This Centre closed in 2011/12 upon the retirement of Prof. O'Moore from the full-time faculty at Trinity.
Designation as National Centre
In January 2014, following the appointment of Prof. O'Moore as an adjunct Professor at Dublin City University, an Anti-Bullying Centre opened at Dublin City University where it is under the academic leadership of Dr. James O'Higgins Norman.
In May 2014, the Centre was re-launched as the National Anti-Bullying Research and Resource Centre by the Minister for Education and Skills Ruairí Quinn TD and the Tánaiste Éamon Gilmore TD at a ceremony in Dublin City University. The Minister also announced on the same day that his Department would provide funding to the Anti-Bullying Centre.
The aims of the Centre are:
To conduct research into the multi-level and multi-factorial nature of workplace and school bullying.
The creation of greater awareness and understanding of bullying behaviour.
The promotion of ways and means by which bullying behaviour may be prevented or reduced.
To support the implementation of the National Action Plan on Bullying.
In September 2014, the Centre hosted the 1st National Cyberbullying Conference at Dublin Castle. The conference was supported by the Government of Ireland and was attended by representatives from all of the major social networks.
Research Activity
Researchers currently at the Centre undertook and published the first national studies on school, workplace, and homophobic bullying in Ireland and have contributed to ongoing initiatives to prevent and reduce bullying behaviour in schools, organisations and businesses including the Report of the Taskforce on Bullying in the Workplace (2000) and the National Action Plan on Bullying (2013).
The Centre's staff has received substantial funding from the Calouste Gulbenkian Foundation, the Department of Education, the Health & Safety Authority, the Irish Research Council, the Equality Authority and from the EU for research projects in the area of school bullying and violence. Staff at ABC have participated in more than 13 EU-funded research projects on bullying and cyberbullying prevention.
References
External links
National Anti-Bullying Centre
Organisations based in Dublin (city)
Dublin City University
Harassment and bullying
1996 establishments in Ireland | National Anti-Bullying Centre | [
"Biology"
] | 506 | [
"Harassment and bullying",
"Behavior",
"Aggression"
] |
42,992,543 | https://en.wikipedia.org/wiki/Students%20for%20the%20Exploration%20and%20Development%20of%20Space | Students for the Exploration and Development of Space (SEDS) is a non-profit international student organization whose purpose is to drive space advocacy of space exploration and development through educational and engineering projects.
History
Students for the Exploration and Development of Space was founded in 1980 at MIT by Peter Diamandis, Princeton University by Scott Scharfman, and Yale University by Richard Sorkin, and consists of an international group of undergraduate and graduate students from a diverse range of educational backgrounds and universities who are working to promote space. SEDS is a chapter-based organization with chapters in Italy, Canada, India, Israel, Mexico, Nepal, Nigeria, Philippines, South Africa, Spain, Turkey, United Kingdom, United States, Sri Lanka, and Zimbabwe. The permanent National Headquarters for SEDS-USA resides at MIT and that of SEDS-India resides at Vellore Institute of Technology. Though collaboration is frequent, each branch and chapter is independent and coordinates their own activities and projects.
1980s
SEDS was founded on September 17, 1980, primarily by Peter Diamandis, Scott Scharfman, Richard Sorkin, Robert D. Richards, and Todd B. Hawley and their first meeting was held on October 30, 1980. After the initial meetings in 1980, SEDS president Peter Diamandis wrote a letter to the editor of Omni magazine deploring the status of the space program and asking students to help make a difference. The letter, published in Omni in early 1981, attracted students from around the world to SEDS. This laid the foundations for the first SEDS international conference, held at George Washington University between July 15–19, 1982. As the decade progressed, SEDS continued to have more international conferences, which rotated among schools including George Washington University (again), University of Alabama in Huntsville, and Caltech. During the end of the decade, UKSEDS was founded at the Science Museum (London) and held their first conference at the University of Cambridge during November 25–26, 1989.
1990s
During the 1990s, SEDS continued to host a national conference each year, sometimes in conjunction with the International Space Development Conference through 1997, when the last "SEDS National Conference" was held (conferences would re-appear 7 years later as the "SEDS SpaceVision Conference"). UKSEDS continued to have national conferences at rotating locations each year. During the last years of the decade, there was a major decline in SEDS leadership and a connected drop in the number of member chapters around the United States.
2000s
In 2004, the SEDS National Conferences were re-established by MITSEDS and hosted on the campus of the Massachusetts Institute of Technology on November 11–14. The conference was renamed the SEDS SpaceVision conference and featured many speakers who would return year after year during this decade, including Loretta Hidalgo Whitesides, founder Dr. Robert Richards, Rick Tumlinson, George T. Whitesides, Robert Zubrin, and Pete Worden. The SpaceVision conference then visited University of Illinois at Urbana-Champaign (2005), University of Central Florida (2006), the Massachusetts Institute of Technology (2007), Texas A&M University (2008), University of Arizona (2009), University of Illinois at Urbana-Champaign (2010), University of Colorado at Boulder (2011), University at Buffalo (2012), Arizona State University (2013), UNC Chapel Hill (2014), Boston University (2015), Purdue (2016), University of Central Florida (2017), University of California, San Diego (2018), Arizona State University (2019), virtually for 2020, Rice University (2021), University of Chicago (2022) and Georgetown University (2023). During this time, UKSEDS continued to have one national conference each year. SEDS India, after hosting the SEDS International conference in 2007, continued with SEDS India National Conferences every year since 2009 at Vellore Institute of Technology, India. SEDS also began exploring innovative national projects such as fund-raising for a joint SEDS chapter Zero-G flight and designing an innovative national Rockoon competition modeled after the Ansari X PRIZE.
Active SEDS-USA projects
SEDS-USA organizes annual and rolling projects to engage its members in space-related activities. Two such projects are:
SEDS High-Power Rocketry Competition
This is a competition between chapters designed to challenge students in high-power rocketry. The goal of the competition is to launch a rocket, designed and built by the chapter members, to an altitude of 10,000 feet above sea-level. This competition has now successfully been running since 2011. The winner of the 2012 competition was Purdue-SEDS.
Student NewSpace Business Plan Competition
Started in 2011, this competition is co-organized with the Space Frontier Foundation and aims to provide students with a real-world experience in entrepreneurship applied to the space industry. Students are required to develop space-scalable business models that will advance the NewSpace movement and are judged by a panel of 5 experts who have had several years of experience in space entrepreneurship. The winners of the 2011 and 2012 competitions were Illinois State University and Iowa State University respectively.
International branches
SEDS is organized by country, region, and chapter. There is a large contingent of SEDS chapters in the United States, which are governed regionally and nationally by SEDS-USA. SEDS India has nine SEDS chapters under it and is headquartered at Vellore Institute of Technology. UKSEDS is composed of five regions across the United Kingdom and has its headquarters at the British Interplanetary Society HQ in London. There are other national sections of SEDS across the world, notably SEDS-Canada, SEDS South Africa, and SEDS Zimbabwe, which has four chapters and a junior chapter. Student leaders of the international groups convene as SEDS-Earth, the global governing body of SEDS. SEDS is an organization member of the Alliance for Space Development.
SEDS-USA
SEDS-USA is the governing body of all chapters in the United States, and is the largest and original branch of SEDS. It is overseen by a national Board of Directors, Board of Advisors and a Board of Trustees. An integral aspect of SEDS-USA is the Council of Chapters (CoC). This council consists of national representatives of each chapter and is led by the Chair of the Council of Chapters. The CoC meets via teleconference to exchange updates between individual chapters and the national board. The 2022–23 national directors of SEDS-USA are listed below.
UKSEDS
UK Students for the Exploration and Development of Space (UKSEDS) is the national student space society of the United Kingdom. Established in 1988, it is dedicated to promoting the exploration and development of space by inspiring, educating, and supporting students and young professionals interested in the space industry. UKSEDS provides a platform for student collaboration on space projects, organises high-profile conferences and workshops, and conducts outreach activities aimed at fostering interest in space science and engineering among young people. The organisation acts as a bridge, building strong links between students, academia, and the wider space industry, both within the UK and internationally.
Founding and Early History
UKSEDS was inspired by the efforts of students who attended the first International Space University (ISU) Space Studies Program held at MIT in 1988. Recognizing the potential to create a national community of space enthusiasts, these students organised a founding conference at London’s Science Museum in March 1989. Later that year, a full conference was held at Cambridge University, cementing UKSEDS as a key player in the UK's space community.
In 2013, UKSEDS celebrated its 25th anniversary. Former committee members shared insights into UKSEDS’ development and contributions over the years. Dr Chris Welch, UKSEDS Chair from 1993–1995, recalled his initial involvement with SEDS and ISU during the International Astronautical Congress (IAC) in Brighton in 1987, where he met key figures like Peter Diamandis and Todd Hawley.
Dr Ralph D. Lorenz, a founding committee member from 1988–1989, emphasised the importance of student-driven initiatives in sustaining UKSEDS amidst existing organisations like the British Interplanetary Society (BIS) and the Royal Aeronautical Society (RAeS). Similarly, Richard Osborne highlighted the critical roles of Chris Welch and Mark Bentley in ensuring the organisation's continuity during challenging periods in the early 1990s.
Activities and Initiatives
UKSEDS offers a wide range of activities designed to engage students and foster their development:
National Student Space Conference (NSSC): An annual event that brings together students, academics, and industry professionals to discuss the latest advancements in space exploration and development. The NSSC features keynote speeches, panel discussions, workshops, and a careers fair.
Competitions and Challenges: Regular events such as the Satellite Design Competition encourage students to apply theoretical knowledge to practical projects, fostering innovation and technical skills.
Workshops and Webinars: Hands-on training sessions and talks by industry leaders help members develop technical and professional skills. Topics range from rocketry and satellite design to leadership and project management.
Outreach Programmes: UKSEDS organises public engagement events to inspire the next generation of scientists and engineers. These include school visits, public lectures, and participation in STEM fairs.
Project Support: Provides funding, mentorship, and resources for student-led space projects across universities in the UK. This support enables students to undertake ambitious projects, from CubeSats to high-altitude balloons.
Notable Projects and Initiatives
UKSEDS has undertaken numerous technical space projects, including:
The Fluid Loop Actuator (FLA): Developed by UKSEDS members at the University of Kent and Canterbury High School, this device was designed to assist astronauts in zero gravity. It was test flown on parabolic flights by the European Space Agency (ESA) in 1993.
ASPIRE I: A sounding rocket developed by members from the Universities of Bath, Bristol, Cambridge, and Kent. Sponsored by Serco Space, British Airways, Irvin Parachutes, ICI, and Dynamit Nobel, ASPIRE I was launched in 1992 and once held UK amateur rocketry records for speed and altitude.
Espy Microsatellite: An educational microsatellite intended for Low Earth Orbit (LEO) launch, aimed at engaging educational organisations, particularly schools, with space projects. Although ultimately not launched, it represented an early attempt at integrating educational outreach with space technology.
UKube-1 Payload (myPocketQub442): Part of the UK’s first CubeSat mission, contributing to small-scale satellite research and development.
Asteroid Search Campaigns: Collaborations with the International Asteroid Search Collaboration (IASC) to engage students in asteroid detection and tracking initiatives.
Impact on the UK Space Community
With over 1,400 members, UKSEDS has become a vital part of the UK’s space ecosystem. It has nurtured countless students who have gone on to pursue successful careers in academia, industry, and government. Through its events and partnerships, UKSEDS has also helped to raise awareness of the importance of space in addressing global challenges, from climate change to technological innovation.
By acting as a hub for collaboration and innovation, UKSEDS continues to inspire and empower the next generation of space professionals in the United Kingdom.
Structure and Governance
UKSEDS operates under the guidance of an Executive Committee, elected annually at the organisation’s Annual General Meeting (AGM) during its flagship conference, the National Student Space Conference (NSSC). The committee is responsible for overseeing day-to-day operations, planning events, and ensuring alignment with the organisation’s goals.
In addition to the Executive Committee, UKSEDS is supported by a Board of External Trustees, who are appointed for three-year terms. The trustees provide strategic oversight and ensure the organisation remains sustainable and impactful.
The 2024/25 Executive Committee was elected during the 36th NSSC in March 2024 and includes the following members:
Partnerships and Affiliations
UKSEDS collaborates with various organisations to advance its mission, including:
British Interplanetary Society: A partnership that facilitates knowledge exchange and collaborative projects.
European Space Agency (ESA): Provides opportunities for UKSEDS members to engage with ESA missions and programs.
Industry Partners: Collaborations with companies like Serco Space, British Airways, and Dynamit Nobel support UKSEDS projects and competitions.
In 2013, UKSEDS formalised a Memorandum of Understanding with the British Interplanetary Society, enhancing cooperation between young members and experienced professionals.
Notable Alumni and Past Committee Members
UKSEDS has had many prominent individuals serve on its Executive Committee, contributing to its development and influence in the space sector. Some notable past committee members include:
Will Marshall – Co-founder and CEO of Planet Labs, served as a key member of the UKSEDS Executive Committee during his student days, going on to lead one of the most successful space-based Earth imaging companies.
Libby Jackson – Head of Human Spaceflight and Exploration at the UK Space Agency, was a former UKSEDS committee member who went on to become one of the UK's most influential figures in human spaceflight.
Mark Bentley – Former Chair (1999/2000), instrumental in revitalising UKSEDS during challenging periods.
Andrew Ball – Former Secretary (1994-1996), now working on Mars exploration for the European Space Agency in the Netherlands.
Jason Hatton – Vice Chair of the Founding Committee (1988-89), now Biology and Environmental Monitoring Science Coordinator in the ISS Utilisation and Astronaut Support Department at ESA ESTEC.
SEDS-Canada
SEDS-Canada is a federally incorporated not-for-profit organization based in Toronto, Canada, whose mandate is to advocate for the exploration and development of space through non-partisan political advocacy, conferences, student competitions, and chapter grants. The organization was initiated in early 1981 by entrepreneur Bob Richards, and it was re-established in 2014 by a group of students from the University of Toronto and the University of Western Ontario, after several years of inactivity. SEDS-Canada currently has eleven university chapters operating across the country.
As part of their advocacy goals, SEDS-Canada seeks to engage Canadian policy makers and electoral candidates at all levels of government in a multi-year effort with the aim of defending cuts to good space policy, and campaigning for new policies to ensure Canadian leadership in niche areas of space exploration and development.
SEDS-Turkey
Space Exploration and Development of Space Turkey, founded in March 2017 by Hadican Çatak at Hacettepe University, is the first and only national space, and entrepreneurial organization with its 350+ active members and branches in 8 universities as of January 2019.
SEDS TR's goal is to gather all interested undergraduates, master's degree students, and doctoral students and to carry out tasks that help them improve their career prospects in their field of activity by establishing a common working platform.
In order to reach this goal, SEDS TR has been working on engineering projects, organizing events and extending its area of effect by founding SEDS organizations in universities throughout Turkey and in respect to this, SEDS is trying to make operations and work done mentioned above accessible to every other student in Turkey.
SEDS-UAE
The SEDS-UAE Chapter is based at the Our Own English High School in Abu Dhabi. This chapter was founded by a high school student, Nishirth Khandwala. Members of SEDS UAE engage themselves in various activities and programs such as the International Asteroid Search Campaign.
SEDS South Africa
SEDS-South Africa is South Africa's national student Space society, and is the governing body of all SEDS chapters in South Africa. SEDS South Africa is made up of students and young professionals in Southern Africa who are interested in Space exploration and development. This includes engaging government policymakers, amateur satellite building, model rocketry, manufacturing in Space, student and young professionals collaboration, connecting with the Space industry, ham amateur radio, analogue Space missions, Space exploration, and Space technology to benefit humankind.
SEDS South Africa facilitates the education of people about the benefits of Space, by supporting a network of interested students and young professionals, and providing opportunities to inspire them and develop their leadership skills. SEDS South Africa's founding branch is the University of Cape Town, SEDS-SA-UCT. Branches include:
SEDS-SA-Wits,
SEDS-SA-UP, and
SEDS-SA-UCT.
SEDS India
SEDS-India is the governing body of SEDS in India with its headquarters at Vellore Institute of Technology. SEDS India was founded in 2004 by Pradeep Mohandas and Abhishek Ray. The first chapter was established in Mumbai at PIIT, New Panvel. SEDS India governs affiliated chapters in India at various universities, including Vellore Institute of Technology, Veltech University, Birla Institute of Technology & Science Pilani-Goa, Sri Ramakrishna Engineering College and SASTRA University. Chapter affairs are controlled by the Local Chapter Committee which reports to the Executive Board of SEDS India. The Executive Board of SEDS India consists of six Board Members who are selected through a voting process, with all individual members of SEDS India being eligible to vote. The Permanent Trustee of SEDS India is Geetha Manivasagam, Vellore Institute of Technology. The advisory panel has multiple dignitaries on its board, including the Associate Director of Vikram Sarabhai Space Center.
The main outreach program of SEDS India is called OneSpace. OneSpace was founded to spread awareness about and engagement with space among underprivileged children in rural India and children residing in local orphanages. Attempts have also been made by SEDS India to outreach to northeast India, where access to space education and technical projects is more difficult. These efforts were led with the help of Angaraj Duara, an alumnus of Maharishi Vidyamandir Shilpukhuri, Guwahati, and established seven chapters in Assam. They are the Army Public School Narangi, Sharla Birla Gyan Jyoti School Guwahati, IIT-Guwahati, Handique Girls College, Royal Global Institute - RSET Guwahati, Donbosco Public School Panbazar and Tezpur University. SEDS-APSN was the first chapter in northeast India. A separate SEDS-NorthEast governing body oversees activities in the northeast.
SEDS (Singapore)
SEDS (Singapore), founded in July 2019 by Vairavan Ramanathan and Nick Lee from National University of Singapore and the Nanyang Technological University respectively, is the first and only national space and entrepreneurial organization in Singapore. The goal of SEDS Singapore is to provide a platform for students of all backgrounds based in Singapore to actively participate in ushering in a new space age.
Currently, there are 3 SEDS chapters under SEDS (Singapore). NUS SEDS based in National University of Singapore. SEDS-NTU based in Nanyang Technological University. SEDS-SUTD based in Singapore University of Technology and Design.
Current Active Projects of SEDS (Singapore):
SEDS Sri Lanka
The most widespread astronomy related organization in Sri Lanka, SEDS Sri Lanka provides myriad opportunities to enthusiastic school children and university undergraduates alike. Founded in September 2018 by then graduate, Amila Sandun Basnayake and undergraduate, Thilan Harshana, currently the main organization SEDS Sri Lanka governs 16 chapters established under it. Hailing from a number of government and private universities, as well as a separate chapter for school children named SEDS Juniors, a wide range of activities are carried out throughout the year.
Evolving rapidly into an island-wide platform that serves to educate, provide opportunity for participation in multi-level events, further aspirations professionally and academically, as well as an ideal method to explore all aspects related to aviation and aerospace, SEDS Sri Lanka is a perfect place for anyone to develop their interests in this field.
These opportunities are represented in many ways such as both onsite and online workshops, SEDS Space Talks, competitions and citizen scientist ventures and educational programs for juniors. Among these, it is of importance to note the first high altitude balloon launched by Sri Lanka, under the project SERENDIB 1.0, the Hackathon, NASA Space Apps conducted in collaboration with NASA, and the numerous asteroid hunts held in collaboration with Pan-STARRS.
SEDS Philippines
SEDS Philippines (SEDSPH) is the official Philippine chapter of the Students for the Exploration and Development of Space or SEDS. It is a student-led, non-profit organization that functions to promote the idea of space exploration and space technology in the country, provide a community for students with a common interest in space, supply opportunities and networks that will enhance their skills, foster growth and confidence among them, and empower their impact in the space sector.
To reinforce these missions, SEDSPH aims to create local and international opportunities for Filipino students in the space industry.
Macedonian SEDS
Macedonian Students for the Exploration and Development of Space (MK-SEDS / МК-СИРК) is the national and regional governing body for SEDS Chapters in Macedonia and Europe.
MK-SEDS initially started in 2019 as a self-organized and student-run Macedonian Cosmic Institute at the Ss. Cyril and Methodius University in Skopje on the initiative of few students.
On October 18, 2020, students, alumni, alumnae and youth from Ss. Cyril and Methodius University of Skopje, Goce Delchev University of Shtip and St. Kliment Ohridski University of Bitola united in their intention to represent the force of Good, Beauty and Truth in the cosmic community of planet Earth adopted the Decision for registration of the Macedonian STUDENTS FOR THE EXPLORATION AND DEVELOPMENT OF SPACE.
The permanent Headquarters for MK-SEDS resides at the Faculty of Computer Science and Engineering, Ss. Cyril and Methodius University in Skopje.
SEDS Zimbabwe
Zimbabwe has multiple SEDS chapters at its major universities namely University of Zimbabwe, National University of Science and Technology, Midlands State University and Chinhoyi University of Technology. It also has a junior SEDS chapter that is aimed at introducing space education to students in high schools. In December 2021, SEDS MSU was one of the 10 teams in the world to be part of the Global Satellite Tracking Initiative where they were recipients of equipment to set up a ground station at Midlands State University.
Notable student leaders
Jeff Bezos, Princeton
Eric C. Anderson, Co-Founder and Chairman of Virginia-based Space Adventures, Ltd., the first commercial spaceflight company—whilst enrolled as a student at the University of Virginia, he started a chapter of Students for the Exploration and Development of Space.
See also
Outer space
Yuri's Night
Space Frontier Foundation
National Space Society
The Planetary Society
Mars Society
NewSpace
Peter Diamandis
Robert D. Richards
Todd B. Hawley
References
External links
Map of SEDS Chapters Worldwide
SEDS-APSN Website
Space organizations
Astronomy organizations
Space
Student organizations established in 1980
Space advocacy organizations
Space colonization
Human spaceflight | Students for the Exploration and Development of Space | [
"Astronomy"
] | 4,725 | [
"Space advocacy organizations",
"Astronomy organizations",
"Space organizations"
] |
42,992,666 | https://en.wikipedia.org/wiki/Command%20Query%20Responsibility%20Segregation | In information technology, Command Query Responsibility Segregation (CQRS) is a system architecture that extends the idea behind command–query separation (CQS) to the level of services. Such a system will have separate interfaces to send queries and to send commands. As in CQS, fulfilling a query request will only retrieve data and will not modify the state of the system (with some exceptions like logging access), while fulfilling a command request will modify the state of the system.
Many systems push the segregation to the data models used by the system. The models used to process queries are usually called read models and the models used to process commands write models.
Although its origin is usually attributed to Greg Young in 2010, everything indicates that the precursor of CQRS was Udi Dahan who in August 2008 published on his blog a training course that aimed to apply CQRS together with SOA and in more detail in December 2009 in the article Clarified CQRS.
References
External links
CQRS Journey by Microsoft patterns & practices
DDD/CQRS/Event Sourcing List
The CQRS Frequently Asked Questions
CQRS - a new architecture precept based on segregation of commands and queries
Systems architecture
Software architecture | Command Query Responsibility Segregation | [
"Engineering"
] | 251 | [
"Systems engineering",
"Design",
"Systems architecture"
] |
42,992,901 | https://en.wikipedia.org/wiki/Giosu%C3%A8%20Sangiovanni | Giosuè Edoard Sangiovanni (15 January 1775 – 17 May 1849) was an Italian zoologist, the first professor of comparative anatomy in Italy and an early exponent of evolution.
Born at Laurino in the kingdom of Naples, he followed his education in philosophy and mathematics at Naples with medical study at the Ospedale degli Incurabili there. With the fall of the Napoleonic Neapolitan Republic of 1799, Sangiovanni fled to exile in Paris. There, during the Napoleonic Empire he was a pupil of the prominent French zoologists Jean-Baptiste de Lamarck. In his distinguished career Sangiovanni was enrolled as a Chevalier of the Legion of Honor.
Sangiovanni was supportive of Lamarck and Erasmus Darwin's evolutionary ideas. He obtained a copy of Zoonomia and walked around Paris for several weeks with it in his pocket.
Called to Naples in 1806, at the reorganization of the university, he planned and brought to fruition the university's Museo Zoologico and held the first chair of comparative anatomy in the faculty of natural sciences.
He died after an extended illness, in retirement at Posillipo near Naples.
Notes
1775 births
1849 deaths
Italian zoologists
Proto-evolutionary biologists
People of the Parthenopean Republic
People from the Kingdom of Naples
Scientists from the Kingdom of the Two Sicilies | Giosuè Sangiovanni | [
"Biology"
] | 279 | [
"Non-Darwinian evolution",
"Biology theories",
"Proto-evolutionary biologists"
] |
42,992,981 | https://en.wikipedia.org/wiki/Module%20of%20covariants | In algebra, given an algebraic group G, a G-module M and a G-algebra A, all over a field k, the module of covariants of type M is the -module
where refers to taking the elements fixed by the action of G; thus, is the ring of invariants of A.
See also
Local cohomology
References
M. Brion, Sur les modules de covariants, Ann. Sci. École Norm. Sup. (4) 26 (1993), 1 21.
M. Van den Bergh, Modules of covariants, Proceedings of the International Congress of Mathematicians, Vol. 1, 2 (Zurich, 1994), Birkhauser, Basel, pp. 352–362, 1995.
Module theory | Module of covariants | [
"Mathematics"
] | 160 | [
"Fields of abstract algebra",
"Module theory"
] |
42,993,306 | https://en.wikipedia.org/wiki/Are%20Quanta%20Real%3F | Are Quanta Real?: A Galilean Dialogue (1973) is a book by Swiss-American physicist J.M. Jauch, in which the three main characters meet over the period of several days to discuss various interpretations and philosophical consequences of quantum mechanics. Are Quanta Real? was inspired by and written in the style of Galileo's Dialogue Concerning the Two Chief World Systems. In the book, Jauch "resurrects" Galileo's three characters, Salviati, Sagredo, and Simplicio, centuries after their deaths to resume their previous dialogue in light of new developments in natural philosophy, specifically, quantum mechanics. The three characters engage in a series of debates and dialectic discussions to better their understanding of quantum phenomena using a series of thought experiments.
In a foreword to the 1989 edition, Douglas Hofstadter explains how the book initially "electrified" him and offered a sense of encouragement while he was in the initial stages of writing Gödel, Escher, Bach: an Eternal Golden Braid.
Are Quanta Real? received positive reviews from scientific journals and popular science magazines, has inspired essays on philosophy and science and was a finalist for a National Book Award.
References
Popular physics books
Quantum mechanics
1973 books | Are Quanta Real? | [
"Physics"
] | 252 | [
"Quantum mechanics",
"Works about quantum mechanics"
] |
42,993,331 | https://en.wikipedia.org/wiki/Time-dependent%20viscosity | In continuum mechanics, time-dependent viscosity is a property of fluids whose viscosity changes as a function of time. The most common type of this is thixotropy, in which the viscosity of fluids under continuous shear decreases with time; the opposite is rheopecty, in which viscosity increases with time.
Thixotropic fluids
Some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity and a non-linear stress-strain behavior in which the longer the fluid undergoes shear stress, the lower its viscosity becomes. A thixotropic fluid is one that takes time to attain viscosity equilibrium when introduced to a step change in shear rate. When shearing in a thixotropic fluid exceeds a certain threshold, it results in a breakdown of the fluid's microstructure and the exhibition of a shear thinning property.
Certain gels or fluids that are thick (viscous) under static conditions will begin to thin and flow as they are shaken, agitated, or otherwise stressed. When stress ceases, they regress to their more viscous state after a passage of time. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids. Others, such as yogurt, take much longer and can become nearly solid. Many gels and colloids are thixotropic materials, exhibiting a stable form at rest but becoming increasingly fluid when agitated.
Examples and applications
Cytoplasm, synovial fluid (found in joints between some bones), and the ground substance in the human body are all thixotropic, as is semen. Some varieties of honey (e.g.heather honey)can exhibit thixotropy under certain conditions.
Some clays (including bentonite and montmorillonite) exhibit thixotropy, as do certain clay deposits found in caves (slow flowing underground streams tend to layer fine-grained sediment into mudbanks that initially appear dry and solid but then become moist and soupy when dug into or otherwise disturbed). Drilling muds used in geotechnical applications can be thixotropic.
Semi-solid casting processes such as thixomoulding use the thixotropic property of some alloys (mostly light metals, e.g. bismuth) to great advantage. Within certain temperature ranges and with appropriate preparation, these alloys can be injected into molds in a semi-solid state, resulting in a cast with less shrinkage and other superior properties than those cast in normal injection molding processes.
Solder pastes used in electronics manufacturing printing processes are thixotropic.
Many kinds of paints and inks (e.g. the plastisols used in silkscreen textile printing) exhibit thixotropic qualities. In many cases it is desirable for an ink or paint to flow sufficiently fast to form a uniform layer, but then resist further flow (which on vertical surfaces can result in sagging). Thixotropic inks that quickly regain a high viscosity are used in CMYK-type printing processes; this is necessary to protect the structure of the dots for accurate color reproduction.
Thread-locking fluid is a thixotropic adhesive that cures anaerobically.
Thixotropy has been proposed as a scientific explanation of blood liquefaction miracles such as that of Saint Januarius in Naples.
Other examples of thixotropic fluids are gelatine, shortening, cream, xanthan gum solutions, aqueous iron oxide gels, pectin gels, hydrogenated castor oil, carbon black suspension in molten tire rubber, many floc suspensions, and many colloidal suspensions.
Rheopectic fluids
Basically the mirror of thixotropy, rheopectic fluids are an even rarer class of non-Newtonian fluids that exhibit a time-dependent increase in viscosity; they thicken or solidify when shaken or agitated. The longer they undergo a shearing force, the higher their viscosity becomes, as the microstructure of a rheopectic fluid builds under continuous shearing (possibly due to shear-induced crystallization).
Examples and Applications
Examples of rheopectic fluids include some gypsum pastes, printer inks, and lubricants.
There is also aggressive ongoing research into rheopectic materials especially with regard to potential uses in shock absorption. In addition to obvious potential military applications, rheopectic padding and armor could offer significant advantages over alternative materials currently in use in a wide range of fields from sporting goods and athletic footwear to skydiving and automobile safety.
Additional insights into rheopecty and the possible uses of rheopectic fluids can be gained through further research into the physics of hysteresis.
See also
Fluid dynamics
Viscosity
Rheopecty: The longer the fluid is subjected to a shear force, the higher the viscosity. Time-dependent shear thickening behavior.
Thixotropy: The longer a fluid is subjected to a shear force, the lower its viscosity. It is a time-dependent shear thinning behavior.
Shear thickening: Similar to rheopecty, but independent of the passage of time.
Shear thinning: Similar to thixotropy, but independent of the passage of time.
Notes
References
J. R. Lister and H. A. Stone (1996). Time-dependent viscous deformation of a drop in a rapidly rotating denser fluid. Journal of Fluid Mechanics, 317, pp 275–299 doi:10.1017/S0022112096000754
Reiner, M., and Scott Blair, Rheology terminology, in Rheology, Vol. 4 pp. 461, (New York: Achedemic Press, 1967)
Viscosity | Time-dependent viscosity | [
"Physics"
] | 1,248 | [
"Physical phenomena",
"Physical quantities",
"Wikipedia categories named after physical quantities",
"Viscosity",
"Physical properties"
] |
42,993,804 | https://en.wikipedia.org/wiki/Rational%20series | In mathematics and computer science, a rational series is a generalisation of the concept of formal power series over a ring to the case when the basic algebraic structure is no longer a ring but a semiring, and the indeterminates adjoined are not assumed to commute. They can be regarded as algebraic expressions of a formal language over a finite alphabet.
Definition
Let R be a semiring and A a finite alphabet.
A non-commutative polynomial over A is a finite formal sum of words over A. They form a semiring .
A formal series is a R-valued function c, on the free monoid A*, which may be written as
The set of formal series is denoted and becomes a semiring under the operations
A non-commutative polynomial thus corresponds to a function c on A* of finite support.
In the case when R is a ring, then this is the Magnus ring over R.
If L is a language over A, regarded as a subset of A* we can form the characteristic series of L as the formal series
corresponding to the characteristic function of L.
In one can define an operation of iteration expressed as
and formalised as
The rational operations are the addition and multiplication of formal series, together with iteration.
A rational series is a formal series obtained by rational operations from
See also
Formal power series
Rational language
Rational set
Hahn series (Malcev–Neumann series)
Weighted automaton
References
Further reading
Droste, M., & Kuich, W. (2009). Semirings and Formal Power Series. Handbook of Weighted Automata, 3–28.
Sakarovitch, J. Rational and Recognisable Power Series. Handbook of Weighted Automata, 105–174 (2009).
W. Kuich. Semirings and formal power series: Their relevance to formal languages and automata theory. In G. Rozenberg and A. Salomaa, editors, Handbook of Formal Languages, volume 1, Chapter 9, pages 609–677. Springer, Berlin, 1997
Abstract algebra
Formal languages
Mathematical series | Rational series | [
"Mathematics"
] | 424 | [
"Sequences and series",
"Mathematical structures",
"Series (mathematics)",
"Calculus",
"Mathematical logic",
"Formal languages",
"Abstract algebra",
"Algebra"
] |
42,995,689 | https://en.wikipedia.org/wiki/Colorplexer | Color television as introduced in North America in 1954 is best described as being 'colored' television. The system used the existing black and white signal but with the addition of a component intended only for television receivers designed to show color. By careful application this 'colored' signal was ignored by ordinary TV sets and had negligible effect on the appearance of the black and white image. This meant that color programs were viewable on the many existing black and white receivers which fulfilled a requirement for 'compatibility' desired by the television industry. Once the so-called 'composite' video signal containing the color component had been generated it could be handled just as if it were a black and white signal, eliminating the need to replace much of the existing TV infrastructure. Colorplexer was the RCA name for the equipment that created this 'composite' color signal from three separate images each created in the primary colors, Red, Green and Blue supplied by a color video camera. This process was by the standards of the day quite complex and demanded accurate control of all the various parameters involved if an acceptable color image was to be achieved. The simplification afforded by this 'head end' approach became evident and contributed to the gradual acceptance of color programming over the following decades.
National standard
The National Television System Committee, NTSC, standard was the analog television system that was used in most of the North America from 1941 until the mandatory cutover to ATSC in 2009. However, low-power TV stations were permitted to operate with NTSC, for now, but many have since converted to ATSC. This national standard was later adopted (or, in some cases, adapted) in other jurisdictions, such as Japan.
The Second NTSC Standard (525/30, 1941 and later) anticipated that the extant monochrome TV system would eventually incorporate a provision for monochrome-compatible color television. The First NTSC Standard (441/30, pre-1941) had no such expectation, as even the extant motion picture 3-color system, "Three-Strip" Technicolor, was then only five years old. The Second NTSC Standard, as revised for color, sometimes called EIA RS-170a, was operational in North America and elsewhere from 1953 until this standard was replaced by ATSC in the early 21st century.
Central to this revised standard was a mandate for an information stream, at the transmitter, and broadcast to TV sets (receivers), which was independent of whether the signal was monochrome (already in existence since 1941) or color (adopted in 1953).
This significant mandate was satisfied by an encoding device which came to be known as a Colorplexer.
Signal management
Colorplexer (a portmanteau of "color" and "multiplexer") was the RCA trade name for its complex electronic device which encoded discrete red, green and blue 3-color images, as from a color camera, into a composite monochrome-compatible color information stream.
In RCA's recommendation for monochrome-compatible color TV, generally called "NTSC color", each color TV source (as, from a CCU) incorporated its own colorplexer, thereby providing the remaining equipment, all of which were presumed to have originated as a monochrome equipment system, with a signal which could be managed (generated, switched, transmitted, received, etcetera) as if the signal was not color at all, but was an ordinary composite monochrome signal.
This was a strategic decision on RCA's part, and this "one Colorplexer per color source" concept became part of RCA's color TV equipment marketing recommendations. While it made each color source significantly more complicated, hence more expensive, it also obviated the need for major changes to a TV station's signal management system, and the cost of signal management (particularly for networks involving widely separated sources and destinations, such as RCA's wholly owned NBC-TV network) was seen as considerably higher in cost than the color signal sources themselves, as otherwise it would have to be changed from a (composite) Y-only management system into a (component) R-, G- and B-management system (thereby effectively tripling the cost of color signal distribution).
Using today's three-phase electrical system in an analogy, overlaying an R-, G- and B-color TV signal management system upon an existing monochrome TV signal management system would be analogous to requiring public utility power systems to convert from three-phase to nine-phase electricity, an insurmountable cost penalty.
The Second NTSC Standard did not specifically mandate RCA's "one Colorplexer per color source" recommendation, as long as the signal actually transmitted to the signal's end user was monochrome-compatible, and this could have been satisfied by an R, G and B signal management system, and a single Colorplexer at the transmitter, and this would have been adequate for small-market TV stations, particularly those with video sources which were co-located at the station's transmitter site. However, the obvious high cost of R-, G- and B-signal management within a large-market TV station, with separate studio and transmitter sites (sources and destinations separated by perhaps one to tens of miles), or particularly within a TV network, with geographically widely separated sources and destinations (sources and destinations separated by perhaps hundreds to thousands of miles), resulted in adoption of RCA's "one Colorplexer per color source" recommendation almost universally, and particularly after Ampex's introduction of color videotape in 1958 (which was never a component system at all, but was always inherently a composite system), and Ampex's (and, later, RCA's) color videotape systems became essential subsystems of multi-time-zone (national, or, indeed, international) network color TV distribution and transmission.
Initially, the instability of the early Colorplexers caused many operational problems as no two Colorplexers were adjusted alike, and these had to be constantly "tweaked", as did the video sources themselves. Eventually, Colorplexer stability improved, as did the stability of the video sources, and NTSC color would go on to provide consistently good color, and it did so until 2009, nearly 56 years, a remarkable technological achievement, as, compared with "Three-Strip" Technicolor, perhaps the "exemplar" for color motion pictures, which lasted only 19 years (from 1936 to 1955).
Encoder
The R, G, and B primary color signals are weighted and then summed together into the Luma signal, Yʹ (Y prime), which is roughly equivalent to a monochrome signal.
With the addition of inputs from the synchronizing generator, which supplies the blanking and composite synch signals, and inputs from the color burst generator, which supplies the 3.579545 MHz color burst and the "burst gate" signals, the colorplexer, using an "encoder", synthesizes a compatible signal which includes luminance (described earlier) and chrominance (an amplitude-modulated suppressed-carrier signal with "I" and "Q" in quadrature, and which represents the differences between the color signals and the monochrome signal), the combination of which produces a monochrome-compatible color information stream.
The "burst gate" admits eight cycles of the 3.579545 MHz "color burst" and applies this to the "back porch" of each horizontal synch pulse (the vertical synch is unaffected). These eight cycles are just enough to supply a color TV receiver with a reference with which it can correct its own 3.579545 MHz local oscillator as to frequency and phase, phase being the most significant aspect of the process of recovering the "I" and "Q" signals.
The "matrix" adopted by RCA was Y = 0.30R + 0.59G + 0.11B; the three weighting factors were selected such that their sum was 1.0.
As with "prior art" two-color systems, such as pre-1932 Technicolor, the G signal predominates the R signal; and, as with "prior art" three-color systems, such as 1932 and later "Three-Strip" Technicolor, the G and R signals predominate the B signal.
RCA's color system was developed while "Three-Strip" Technicolor was the "gold standard", and Eastman Kodak's Eastmancolor would not completely displace "Three-Strip" Technicolor for another half-decade. Indeed, RCA's P22 CRT phosphor was intended to mimic Technicolor's dramatic color palette.
In most practical color systems, including RCA's, the G signal is taken to be the reference as it has the highest resolution. Indeed, in 1932 to 1944 "Three-Strip" Technicolor, the image was enhanced by printing a monochrome image which was taken from a 0.5G negative (called the "key" image, and hence that color system was really an RGBK system, not unlike graphic arts' YCMK system) on the film's "blank receiver" before the color dyes were applied, as an edge enhancement measure.
Edge enhancement is now a part of many electronically based color systems, but in "Three-Strip" Technicolor's day, it was accomplished photographically from the G image, the sharpest of the three.
Monochrome compatibility
Conventional monochrome TV sets will accept this signal as if there were no chrominance or burst signals at all. A monochrome image, Y, with minimal or no defects (such as moiré, etcetera) will be displayed.
The "I", "Q" and "color burst" signals will be ignored, leaving only the monochrome image.
Color Compatibility
Color TV sets will accept this signal and will, first, separate the monochrome image, Y, and will, second, decode the "I" and "Q" signals, using the extracted "color burst" 3.579545 MHz signal as a phase reference to decode these signals.
Applying the monochrome image and the decoded "I" and "Q" signals to the mathematical inverse of the "matrix" reverse synthesizes the R, G and B primary color signals, which were applied to a "shadow mask" or equivalent TV tube, and which displays a 3-color color image.
References
http://www.americanradiohistory.com/Archive-RCA-Broadcast-News/RCA-77.pdf
Television technology
Video signal | Colorplexer | [
"Technology"
] | 2,204 | [
"Information and communications technology",
"Television technology"
] |
74,475,978 | https://en.wikipedia.org/wiki/Ulrike%20Endesfelder | Ulrike Endesfelder (born 4 July 1983) is a German physicist known for her work in Single-Molecule Microbiology and Super-resolution microscopy. She is the Group Leader of the Research Group Endesfelder and full professor (W3) at the Institute for microbiology and biotechnology at the University of Bonn in Bonn, Germany.
Early life and education
Endesfelder was born on 4 July 1983. From 2002 to 2008, she studied Physics, Astronomy, and Microbiology at the University of Bonn in Bonn, Germany and Stony Brook University, NY, USA. In 2012, she earned her Ph.D. in Physics at the Department of Applied Laser Physics and Laser Spectroscopy at Bielefeld University, Germany.
Career and research
For her postgraduate work, Endesfelder worked as a postdoctoral researcher at the Department of Biotechnology and Biophysics, University of Würzburg (2012/13) and at the Department of Physical and Theoretical Chemistry, Goethe University Frankfurt (2013/14).
Between 2014 and 2020, Endesfelder was a Group Leader at the Department of Systems and Synthetic Microbiology at the Max Planck Institute for Terrestrial Microbiology in Marburg, Germany.
Subsequently, Endesfelder relocated to the United States to work as an Associate Professor (tenure track) at the Department of Physics at the Carnegie Mellon University in Pittsburgh, PA between 2020 and 2021.
Since 2021, Endesfelder has been a Full Professor (W3) at the Institute for Microbiology & Biotechnology at the University of Bonn, Germany.
Endesfelder's group uses tailored quantitative single-molecule tracking and structural super-resolution microscopy methods to understand molecular processes in cells. They are particularly keen on exploring microbial cell biology using fluorescence microscopy and biophysical methods.
Endesfelder is a well-known microscopist and biophysicist. Hence, she is frequently invited to speak at workshops and conferences in the field.
Since 2021, Endesfelder has been an associate editor of Biophysical Reports, an open-access journal run by the Biophysical Society.
Awards and honours
2015–2020 Member of Die Junge Akademie at the Berlin-Brandenburg Academy of Sciences and Humanities and German National Academy of Sciences Leopoldina.
References
Living people
Women in optics
Microscopists
Optical physicists
University of Bonn alumni
1983 births
21st-century German physicists
German women physicists
21st-century women physicists
Bielefeld University alumni | Ulrike Endesfelder | [
"Chemistry"
] | 497 | [
"Microscopists",
"Microscopy"
] |
74,476,808 | https://en.wikipedia.org/wiki/Sungai%20Kolok%20fireworks%20disaster | The Sungai Kolok fireworks disaster was a catastrophic fireworks explosion that occurred at a warehouse on 29 July 2023 in Sungai Kolok, Thailand, killing at least 12 and injuring at least 118, and destroying at least 200 homes and businesses.
References
Explosions in 2023
Explosions in Thailand
Fireworks accidents and incidents
2023 industrial disasters
2023 in Thailand
2023 fires in Asia
Industrial fires and explosions
Narathiwat province
July 2023 events in Thailand
Warehouse fires
Building and structure fires in Asia | Sungai Kolok fireworks disaster | [
"Chemistry"
] | 98 | [
"Industrial fires and explosions",
"Explosions"
] |
74,477,694 | https://en.wikipedia.org/wiki/Consortium%20for%20Execution%20of%20Rendezvous%20and%20Servicing%20Operations | The Consortium for Execution of Rendezvous and Servicing Operations (CONFERS) is a program started by the Defense Advanced Research Projects Agency (DARPA) in 2017. The goal was to address the lack of widely accepted technical and safety standards for on-orbit servicing activities involving commercial satellites. In partnership with NASA, the CONFERS program was to establish a permanent, self-sustaining, and independent forum where industry could engage with the U.S. Government to collaborate and create standards for on-orbit servicing.
In 2017, DARPA provided funding to Advanced Technology International to form the consortium as an industry-led initiative. Since 2018, CONFERS holds annual Global Satellite Servicing Forum conferences.
In 2022, International Standards Organization (ISO) adopted CONFERS’ standard as ISO 24330, Space systems — Rendezvous and Proximity Operations (RPO) and On Orbit Servicing (OOS).
DARPA has transitioned the leadership and funding to CONFERS, Inc., a nonprofit 501(c)(6) organization.
References
DARPA projects
NASA programs
2017 establishments in the United States
501(c)(6) nonprofit organizations
Standards of the United States
Satellites | Consortium for Execution of Rendezvous and Servicing Operations | [
"Astronomy"
] | 229 | [
"Satellites",
"Outer space"
] |
74,478,612 | https://en.wikipedia.org/wiki/Rhabdocline%20laricis | Rhabdocline laricis, also known as Meria laricis, is a hyphomycete fungus in the family Cenangiaceae. In larch conifer trees (Larix), it causes the plant disease larch needle cast, also known as meria needle blight. It is generally harmless in older trees. However, it causes browning of needles, which can slow growth, weaken overall resistance to opportunistic pathogens, and can sometimes outright kill seedlings, making Rhabdocline laricis a threat in tree nurseries.
The fungus is sometimes confused with the similar Hypodermella laricis, which causes larch needle blight. Both fungi can infest the same larch for a more virulent effect.
Taxonomy and nomenclature
The species is traditionally known as Meria laricis. Meria was first described by Jean Paul Vuillemin (Vuill.) in France in 1896. DNA analysis in the 1990s indicated its closest ancestor was the Rhabdocline genus, with the similarity significant enough for the genera of Meria, Hartigiella, and Rhabdocline to be combined as synonyms, with Rhabdocline chosen as the name of the merged genus.
Plant pathology
The needle cast and needle blight affects all species of larch, although it has been speculated that Japanese larches handle it better. It is detected by an appearance of yellow or brown spots on needles during or after wet weather. If moist conditions continue, colorless conidia develop on the lower surface of needles in clusters, and spores begin to grow, appearing as white spots. Browned needles consumed by Rhabdocline laricis eventually wither and drop off the larch.
The fungus is native to Europe, but has since spread elsewhere. Its first reported appearance in North America was in 1942, but probably spread there much earlier.
Disease cycle
Rhabdocline laricis overwinters in the dead terminal tufts of fallen needles that adhere to twigs as well as fallen needles in general. Spores splashed up from these can activate an infection in spring.
Dry weather suppresses Rhabdocline laricis, and moist weather favors it. Experiments suggest that it grows the most at 10–25°C; slight infection can occur from 0–5°C; and none at all over 30 °C.
Control
Rhabdocline laricis is a threat to tree nurseries that are attempting to grow larches such as the Western larch. Even if the infected tree ultimately survives, it may have reduced DBH (diameter) leading to culling by the maintainer for failing to meet the expected size. Fungicide can be used in nurseries, although control in a wider natural forest setting is generally not practical.
Damage from Rhabdocline laricis is not always recognized as such, as the results can be confused with damage from insects or from frost.
Interaction with Hypodermella laricis
The species becomes substantially more problematic when paired with Hypodermella laricis, an ascomycete fungus that lives on Larix, and can produce ill effects more substantial than either plant pathogen alone.
References
Helotiales
Fungal conifer pathogens and diseases
Fungus species | Rhabdocline laricis | [
"Biology"
] | 677 | [
"Fungi",
"Fungus species"
] |
74,479,627 | https://en.wikipedia.org/wiki/Reversible%20Michaelis%E2%80%93Menten%20kinetics | Enzymes are proteins that act as biological catalysts by accelerating chemical reactions. Enzymes act on small molecules called substrates, which an enzyme converts into products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. The study of how fast an enzyme can transform a substrate into a product is called enzyme kinetics.
The rate of reaction of many chemical reactions shows a linear response as function of the concentration of substrate molecules. Enzymes however display a saturation effect where,, as the substrate concentration is increased the reaction rate reaches a maximum value. Standard approaches to describing this behavior are based on models developed by Michaelis and Menten as well and Briggs and Haldane. Most elementary formulations of these models assume that the enzyme reaction is irreversible, that is product is not converted back to substrate. However, this is unrealistic when describing the kinetics of enzymes in an intact cell because there is product available. Reversible Michaelis–Menten kinetics, using the reversible form of the Michaelis–Menten equation, is therefore important when developing computer models of cellular processes involving enzymes.
In enzyme kinetics, the Michaelis–Menten kinetics kinetic rate law that describes the conversion of one substrate to one product, is often commonly depicted in its irreversible form as:
where is the reaction rate, is the maximum rate when saturating levels of the substrate are present, is the Michaelis constant and the substrate concentration.
In practice, this equation is used to predict the rate of reaction when little or no product is present. Such situations arise in enzyme assays. When used to model enzyme rates in vivo , for example, to model a metabolic pathway, this representation is inadequate because under these conditions product is present. As a result, when building computer models of metabolism or other enzymatic processes, it is better to use the reversible form of the Michaelis–Menten equation.
To model the reversible form of the Michaelis–Menten equation, the following reversible mechanism is considered:
{E} + {S}
<=>[k_{1}][k_{-1}]
ES
<=>[k_{2}][k_{-2}]
{E} + {P}
To derive the rate equation, it is assumed that the concentration of enzyme-substrate complex is at steady-state, that is .
Following current literature convention, we will be using lowercase Roman lettering to indicate concentrations (this avoids cluttering the equations with square brackets). Thus indicates the concentration of enzyme-substrate complex, ES.
The net rate of change of product (which is equal to ) is given by the difference in forward and reverse rates:
The total level of enzyme moiety is the sum total of free enzyme and enzyme-complex, that is . Hence the level of free is given by the difference in the total enzyme concentration, and the concentration of complex, that is:
Using mass conservation we can compute the rate of change of using the balance equation:
where has been replaced using . This leaves as the only unknown. Solving for gives:
Inserting into the rate equation and rearranging gives:
The following substitutions are now made:
and
after rearrangement, we obtain the reversible Michaelis–Menten equation in terms of four constants:
Haldane relationship
This is not the usual form in which the equation is used. Instead, the equation is set to zero, meaning , indicating we are at equilibrium and the concentrations and are now equilibrium concentrations, hence:
Rearranging this gives the so-called Haldane relationship:
The advantage of this is that one of the four constants can be eliminated and replaced with the equilibrium constant which is more likely to be known. In addition, it allows one to make a useful interpretation in terms of the thermodynamic and saturation effects (see next section). Most often the reverse maximum rate is eliminated to yield the final equation:
Decomposition of the rate law
The reversible Michaelis–Menten law, as with many enzymatic rate laws, can be decomposed into a capacity term, a thermodynamic term, and an enzyme saturation level. This is more easily seen when we write the reversible rate law as:
where is the capacity term, the thermodynamic term and
the saturation term. The separation can be even better appreciated if we look at the elasticity coefficient . According to elasticity algebra, the elasticity of a product is the sum of the sub-term elasticities, that is:
Hence the elasticity of the reversible Michaelis–Menten rate law can easily be shown to be:
Since the capacity term is a constant, the first elasticity is zero. The thermodynamic term can be easily shown to be:
where is the disequilibrium ratio and equals and the mass–action ratio
The saturation term becomes:
References
Enzyme kinetics
Chemical kinetics
Catalysis
Biochemistry methods
Metabolism
Mathematical and theoretical biology
Systems biology | Reversible Michaelis–Menten kinetics | [
"Chemistry",
"Mathematics",
"Biology"
] | 1,047 | [
"Catalysis",
"Biochemistry methods",
"Chemical reaction engineering",
"Enzyme kinetics",
"Mathematical and theoretical biology",
"Applied mathematics",
"Cellular processes",
"Biochemistry",
"Chemical kinetics",
"Metabolism",
"Systems biology"
] |
74,479,631 | https://en.wikipedia.org/wiki/Susan%20Lyons%20%28engineer%29 | Susan Mary Lyons (born September 1952) is a British engineer who was the Managing Director, Defence (Europe) at British aerospace company Rolls-Royce from 1998 to 2001. Lyons has been awarded an OBE for services to aero engineering.
Education and career
Lyons studied Production Engineering and Production Management at the University of Nottingham, graduating in 1975. After graduating, she began working as an engineer at Rolls-Royce, where she initially served until 1986. She then worked at Precision Castparts Corporation for three years, before returning to Rolls Royce. From 1998-2001 Lyons held the position of Managing Director, Defence (Europe). She also held the position of non-executive director of National Express Group, Investis Digital (beginning in 2001) and was a director at several other British aerospace companies.
Lyons retired from her professional career in 2007.
Recognition
In 1997 Lyons was elected a Fellow of the Royal Academy of Engineering and in 1998 was awarded an Order of the British Empire (OBE) for services to aero engineering. Other recognition includes being shortlisted for the 1997 Veuve Clicquot Business Woman of the Year award and winning the 1999 European Woman of Achievement award in the Business category.
Lyons is a visiting professor in Principles of Engineering Design at Imperial College London.
References
1952 births
Living people
20th-century British engineers
British women engineers
Academics of Imperial College London
Aerospace engineers
Fellows of the Royal Academy of Engineering
Female fellows of the Royal Academy of Engineering
Rolls-Royce people
Officers of the Order of the British Empire | Susan Lyons (engineer) | [
"Engineering"
] | 297 | [
"Aerospace engineers",
"Aerospace engineering"
] |
74,480,194 | https://en.wikipedia.org/wiki/NGC%203646 | NGC 3646 is a galaxy in the Leo constellation that has variously been described as "a strange spiral galaxy" of morphological classication Sc or SAa, or as "a ring-shaped galaxy". It was discovered by German-British astronomer William Herschel on 15 February 1784.
NGC 3646 has a structure consisting of three parts: an inner hub, a rapidly rotating spiral, and an irregular outer ring surrounding the spiral with an angular feature at one point of the ring. Although estimates vary for its distance, the NASA/IPAC Extragalactic Database lists its distance as .
Burbidge et al. estimated that their measurements of motion in the outer ring were not consistent with stable circular orbits. Afanas'ev et al. argue that this conclusion was erroneous, based on incorrect measurements. Instead, they find a galaxy rotation curve that "places the galaxy among the most rapidly rotating and massive systems", "one of the largest and most luminous spirals in the local universe".
NGC 3646 forms an isolated pair with a smaller companion galaxy, NGC 3649. The high rate of star formation in NGC 3646, the low rate in its companion, and the unusual shape of the outer ring in NGC 3646 may have resulted from interactions between these two galaxies.
Supernovae
Four supernovae have been observed in NGC 3646:
SN 1989N (type II, mag. 14.5) was discovered by Celina Mikolajczak et al. on 30 June 1989.
SN 1999cd (type II, mag. 17.9) was discovered by the Lick Observatory Supernova Search (LOSS) on 14 May 1999.
SN 2020abqw (type II, mag. 19.2) was discovered by the Automatic Learning for the Rapid Classification of Events (ALeRCE) on 5 December 2020.
SN 2021abqs (type II, mag. 19.8) was discovered by the ALeRCE on 17 October 2021.
References
External links
Unbarred spiral galaxies
Ring galaxies
Leo (constellation)
3646
06376
34836
Astronomical objects discovered in 1784
Discoveries by William Herschel | NGC 3646 | [
"Astronomy"
] | 436 | [
"Leo (constellation)",
"Constellations"
] |
74,480,273 | https://en.wikipedia.org/wiki/Tiefwerder%20Wiesen | The Tiefwerder Wiesen (lit. German: Tiefwerder meadows) in Berlin is the remnant of the former floodplain landscape in the Havel/Spreetal lowlands. It is situated in the Tiefwerder area and the lowland region of the Pichelswerder River peninsula in the Wilhelmstadt district of Spandau. These wet meadows contain historical Havel River arms and have been protected under Landschaftsschutzgebiet (LSG) (landscape conservation area) since 1960, covering an area of 66.7 hectares. Within the LSG lies the Faule See (Lazy Lake), which emerged from an old arm of the Havel.
The natural floodplain is the last pike spawning area in Berlin. However, due to the lowering of the Havel water level since 1990, the accessibility of the meadows for the pike has significantly deteriorated. Moreover, the German Unity 17 transport project, if implemented, would cause a further drop in the water level, posing an additional threat to the pike's habitat. Endangered species such as the bladder sedge grow in the wet meadows dominated by sedge in Berlin. The LSG serves as an important inner-city link in the Havel biotope network and functions as a flight path for bats and a migration route for the native beaver. Since 2007, Berlin has been considering extending its protected status to a nature reserve.
Territory boundaries
The highly dissected landscape conservation area lies between the Havel, the Havelchaussee, and the Heerstraße (Bundesstraßen B 2/B 5).
It starts in the north with a narrow east tip of the Freiheitswiesen on Tiefwerder. The western boundary runs southwest between an allotment/weekend settlement and a forest and meadow area, then continues along the Faulen See Lake, and finally crosses the Kleiner Jürgengraben ditch. In the lowland area south of the village of Tiefwerder, the boundary turns west and runs along the Kleiner Jürgengraben for a short distance to the Havel River. Along the river and the Havelseenweg, the western border stretches south almost to the Freybrücke (Frey bridge) and, after a short detour, it reaches the Heerstraße on Pichelswerder.
On the eastern side, the boundary starts from the narrow northern tip of the area, omitting the Tiefwerder waterworks. It runs southward along the Havelchaussee and the Havelaltarm Hohler Weg, which flows into the Stößensee Lake. Here, it also runs parallel to the district border with Charlottenburg-Wilmersdorf, which is marked by the S-Bahn embankment of the Spandauer Vorortbahn (Spandau Suburban Railway), located a few meters away from the Havelchaussee. Just before reaching the Stößensee Lake, the LSG border crosses the Hohlen Weg to the west towards the Steffenhorn and runs below the Schulzenwall and Langer Wall along the Hauptgraben back to the north. Then it circles the weekend settlement on the hill of Pichelswerder at the transverse ditch to the Toten Mantel, turns south again below the hill, and reaches the Heerstraße past the Pichelswerder natural gas storage facility. The southern boundary follows Heerstraße for about 300 meters. The landscape conservation area measures approximately 1.6 kilometers in length from north to south and about 900 meters in width, from west to east.
During the German division, the GDR claimed a small part of the Tiefwerder Wiesen as an exclave of the municipality of Seeburg. However, this claim had no consequences due to the opposition of the British authorities.
Geology, natural space, and climate
The Tiefwerder Wiesen is located in the southern part of the Spree where it meets the Havel River. This region is part of the Weichselian glacial valley in Berlin, characterized by thick sands that reach depths of over 20 meters. The Havel River follows a glacial channel in this area and does not extensively utilize the glacial valley.
On the eastern side, separated by the Havelchaussee and the S-Bahn embankment, lies the Schanzenwald forest, which also belongs to the valley sand area of the Spree lowlands. The Schanzenwald merges into the Murellenberge mountains, creating the Murellenschlucht canyon and Schanzenwald forest nature reserve. These hilly areas are part of the northwestern edge of the Teltow Plateau. Interestingly, the Tiefwerder Wiesen and the Schanzenwald forest run parallel to each other, separated by only a few meters, but are now divided by the S-Bahn embankment of the Spandauer Vorortbahn, also known as Olympic Railway. This railroad was built during preparations for the Summer Olympics, which were canceled due to the First World War, and eventually took place in Berlin 20 years later.
To the west of the Havel channel lies the former lowland Börnicker Lake, also known as Birnicker Lake. On its marshy meadows, the Spandauer Südpark (Spandau South Park) was established in 1923, featuring the Südparksee Lake. The channel continues to flow towards Scharfen Lanke and Grimnitzsee, which are located on the opposite side of the Havel, facing the Tiefwerder Wiesen. South of the Heerstrasse, the LSG Tiefwerder-Wiesen is followed by the landscape conservation area Pichelswerder, after which the Havel, which is canalized at Tiefwerder, opens into the southern Berlin Havel Lake chain. The Tiefwerder meadows are assigned to the Brandenburg-Potsdam Havel area (No. 812) in the natural space unit D 12a (East German Lowlands, Central Brandenburg Plates and Lowlands).
The Tiefwerder Wiesen is in a temperate climate zone, transitioning from the Atlantic-influenced climate of Northern/Western Europe to the continental climate of Eastern Europe, which is similar to the outskirts of Berlin.
Anthropogenic influences on flood dynamics
The biotope and landscape function of the Tiefwerder Wiesen also referred to as pike spawning meadows, relies heavily on their flood dynamics, which are greatly influenced by the water level of the Havel River and human activities. The Havel lakes play a significant role in regulating the water levels, resulting in a relatively stable environment. The river’s low gradient averaging about 0.05% (equivalent to 5 cm per kilometer), ensures a serene and tranquil flow through the country.
Middle ages
Archaeological discoveries of vessel fragments, belonging to the Prague type and dating back to the sixth to the eighth century, provide evidence of an early Slavic settlement on the eastern shore of the Faulen See (Lazy Lake), which was known as Wirchen Lake until the 19th century. The Middle Ages saw the presence of a Slavic settlement, although it did not significantly impact the water regime of the region. However, many of the Havel's old water names and the former lake name, likely derived from the settlement's name (Wirchen from Slavic verch/virch = height, elevation - referring to the neighboring Teltow slopes), trace back to this historical period.
Following German settlement, the water level of the Havel experienced a significant rise around 1180, attributed to a backwater in Spandau. This increase was primarily caused by the mill dam of the city of Brandenburg, which played a role in altering the flooding dynamics of the area. Despite water regulations implemented during the pre-industrial period between 1500 and 1750, the water balance of the region remained largely unaffected.
Havel regulations, and Elsgraben
Until the mid-19th century, the vast and intricate network of estuary branches from the Spree and numerous ramifications of the Havel would regularly flood the lowlands between the Spree and Pichelswerder. In 1880 and 1881, the canalization of the Havel, known for its strong meandering at Tiefwerder, and the river regulation during the expansion of the southern harbor at Tiefwerder in 1908 significantly altered the water network. However, the Elsgraben, built in 1832, played a crucial role in maintaining good flood dynamics. This canal diverted floodwaters from the Spree directly into the Tiefwerder Wiesen. Originally navigable until 1886, the Elsgraben gradually filled in around 1930. It connected the (old) Spree opposite the former Otternbucht (approximately at the location of today's Reuter combined heat and power plant) with the Faulen See. The primary purpose of the ditch was to protect Spandau by directing water away from the city through the Faulen See into the Havel in case of floods. Additionally, the Elsgraben facilitated the drainage of the Verlandungsmoor Fließwiese Ruhleben (Flow meadow Ruhleben), a former dead ice channel and the northern continuation of the dry valley Murellenschlucht canyon, into the Tiefwerder Wiesen.
Settlement construction and conflicts of interest
In the early 20th century, the floodplain area underwent significant changes due to settlement construction and industrial development. Embankments were built, narrowing the floodplain over time. In 1816, the fishing village of Tiefwerder was established in a higher and flood-free area, marking the first steps of human settlement in the region. As industrial facilities sprouted in the northern part of the area from 1910 onwards, further changes to the landscape were set in motion. The construction of the Heerstraße, between 1910 and 1912, further divided the Stößensee with an embankment, affecting the nearby Pichelswerder as well. The demand for drinking water from the Tiefwerder waterworks prompted the lowering of the groundwater level, starting in 1914. This change allowed for the construction of allotment colonies and weekend houses to the south of the village and along certain ditches. The freedom meadows (Freiheitswiesen) to the north were filled with rubble after the Second World War.
Today, the remaining floodplain in the Tiefwerder-Wiesen landscape conservation area consists only of a limited lowland area south of the village. To protect the delicate wet meadows, the state of Berlin undertook measures in the 1980s, removing road embankments and filled-in paths. Some of the pathways were replaced with footbridges and bridges, promoting a more sustainable approach to the preservation of the area's natural beauty. In 2005, the Naturschutzamt Spandau (Spandau Nature Conservation Office) issued notices of termination to 67 tenants who had allotment garden plots on state-owned land within the LSG. Though many plots have been cleared and their arbors dismantled, legal disputes arose, with some allotment gardeners successfully contesting the termination in court. Presently, certain residents are voicing opposition to the electric fences erected for the commercial keeping of water buffalo, goats, and sheep. These fences encompass several former recreational areas, and allotment gardeners have been granted the right to use them.
Transport project German Unity 17
Various factors such as the reduction of the Spree inflows in Lusatia (the water volume that the Spree fed to the Havel was more than twice as high as that of the Havel itself at its mouth until 1990, 38 m³/s compared to 15 m³/s) or the deepening of the Havel led to a lowering of the Havel water level since 1990. Additionally, the deteriorating flood dynamics have resulted in limited accessibility of the small remaining area for pike, making it possible only during specific years. For instance, prior to 1990, the water level of 29.55 meters above sea level was undercut on 220 days per year, whereas in the 2000s, it reached about 310 days per year. Meanwhile, the water level in the Havel has been reduced to a minimum.
The transport project "German Unity" 17 (VDE No. 17) has posed a major threat to the flood dynamics of the Tiefwerder Wiesen. This project involves the expansion of waterways to accommodate barges up to 2000 tons, with an unloading depth of up to 2.8 meters to access the western harbor. The federal waterway link Rühen - Magdeburg - Berlin - which is highly controversial for ecological reasons, includes expanding the Lower Havel Waterway, the Elbe-Havel Canal, and the straightening of a section of the Spree River. The entire stretch was to be dredged to a depth of four meters and, depending on the bank profile, to a water level width of 42–55 meters (up to 72 meters in curves).
According to an interim report from the Berlin House of Representatives in February 2009, the transport project could lead to a drop in water levels, resulting in changes to the flooding dynamics of the Tiefwerder Wiesen. It is predicted that water levels might decrease by 1 to a maximum of 13 cm, depending on the discharge situation of low, medium, or high water. As a result, the meadows might no longer experience the same natural flooding patterns they currently do. Despite facing opposition and objections, there are plans to proceed with the project. In response, the state of Berlin aims to protect the Tiefwerder Wiesen by implementing compensatory measures, including artificial irrigation using water from the Havel and the construction of fish ladders. The Federal Waterways and Shipping Administration planned to do this:
Flora and fauna
The description of the species-rich flora and fauna of the Tiefwerder Wiesen refers to the population of the 2000s.
Plants and plant communities
Sedge reeds and reeds
The flooded tall sedge meadows that long dominated the Tiefwerder Wiesen are declining due to increasingly infrequent flooding. However, the riparian sedge, growing up to two meters tall, can still be found along the water bodies' edges. Instead, the wet meadow areas and fallows are now characterized by slender sedge meadows from the sedge genus. The main plant in this community is the slender sedge, a perennial, herbaceous plant that can reach heights between 30 and 150 cm. In the siltation areas, it is joined by the bladder sedge, which is endangered in Berlin and occasionally forms a hybrid with the slender sedge. The slender sedge reed has a long survival capacity with increasing drainage but is displaced by reed canary grass in areas of better-aerated soils. Extensive water swath reeds, also known as giant swaths or sweetgrass, dominate the wetter parts of the meadow, often forming pure stands. These sweetgrass plants can grow up to two meters high. From May to July, the cuckoo campion adds pink flowers and stands up to 60 cm tall in the sedge and reed-rich areas of the meadow. Pennywort and yellow-flowered marsh marigolds also bloom in this period, while the marsh marigold might also have a weaker second flowering phase between July and October. Later in the season, the meadow rue with yellow buttercups (June to August) and poison buttercups, especially in June, contribute to the yellow flowering display. From July to September, the dark purple flowers of the marsh thistle add contrast to the yellow blooms. In early summer, wild rose shrubs like the dog rose showcase many light pink flowers along the paths and shrubbery edges.
Reed belt and floodplain forest relics
In the vast reed and cattail belts of the river arms and ditches, one can experience a beautiful array of colors provided by sporadic purple loosestrife, marsh zest, and the water iris, which is classified as species protected under the Bundesartenschutzverordnung (BArtSchV) (Federal Species Protection Ordinance). The delicate hues of violet-red, burgundy, whitish, and yellow color create a picturesque landscape. The open riparian areas and watercourse edges are characterized by willow bushes and floodplain forest relics, including silver willow and fluttering elm. Especially at the Havelaltarm Toter Mantel, which extends to Heerstraße, a softwood floodplain is preserved. In the zones with rich herbaceous flora, plants like the marsh fern (Theylpteris palustris), marsh ragwort, stiff sedge, and common loosestrife, which was formerly administered in folk medicine for scurvy, diarrhea, and fever. Originally from the Himalayas, the balsam is spreading strongly on wet, nutrient-rich meadows, forming dense stands of dominance. The fast-growing and rapidly multiplying neophyte was first imported to England from Kashmir in 1839, from where it reached the European continent as an ornamental plant. It belongs to the heterosporous plants, which were deliberately introduced ethelochor. Similar to other water lily plants, the yellow pond lily, which is protected in Germany, covers large areas of open water with floating foliage. Rich yellow, hermaphroditic flowers 4 to 12 cm in diameter protrude from its sea of green leaves.
Animals
The Tiefwerder-Wiesen biotope provides a diverse habitat for fish, amphibians, reptiles, insects, birds, and mammals such as bats and the beaver, which has now become a permanent resident after several guest visits.
Fishes
The significance of the Tiefwerder Wiesen as a pike spawning ground lies in the oviposition of the predatory fish. From March to May, the substrate spawner seeks out flooded floodplain meadows or shallow shore areas of standing waters. Here, the pike carefully attaches its eggs to water plants, roots, or branches. While the second traditional Berlin pike spawning meadow at Parschenkessel on Pfaueninsel became inaccessible to the pike years ago, the fish have also been unable to reach Tiefwerder Wiesen since 1990. "With water depths of less than 5 centimeters, it is only possible for juvenile fish to swim through the connection from the main ditch. However, in wetter years, some old fish can manage to do this, ensuring successful spawning in the Tiefwerder Wiesen."
Measuring up to 1.5 meters long, the pike preys on whitefish species such as roach, white bream, and rudd, which are known for peacefully coexisting and spawning in abundance in the ditches and river oxbow lakes, just like river perch. Similarly, the protected turbot, under Annex II of the Fauna-Flora-Habitat (FFH) (Habitats Directive), searches for food only at night and burrows into the bottom during the day, with only its head and tail protruding. Another species of concern, the asp, a member of the carp family, gather in small schools as juveniles but develops into solitary fish as adults. For this fish, survival relies on the accessibility and patency of waterways.
Mammals
The otter, occasionally spotted in the Tiefwerder Wiesen, finds its ideal habitat in the shallow, fish-rich Havelaltarms and the flood plains. This aquatic marten species is listed as threatened on the Berlin Red List of Endangered Species (as of 2003) and is strictly protected under the Bundesartenschutzverordnung (BArtSchV) (Federal Ordinance on the Protection of Species). Despite special surveys and conversation efforts by the state of Berlin to safeguard its population, uncertainties persist about the otter's ability to establish a stable presence in Berlin. Their habitats are constrained by bank construction, water pollution, recreational pressure, and potential losses from traffic and fish traps. Similarly, the beaver also holds the same protection status and has been native to the Upper Havel and Lake Tegel since 1994 as a "true new citizen" with several beaver burrows. From Lake Tegel, the rodent visited the Tiefwerder Wiesen down the Havel several times as a guest. In the meantime (as of 2008), beavers are said to have settled permanently in Tiefwerder.
The Tiefwerder Wiesen serves as a nurturing ground for various wildlife, including foxes and badgers. However, the abundant presence of wild boars has become a concern, with the Senate Department for Urban Development citing their burrowing activity as a contributing factor to the decline of the tall sedge meadows. For the planned designation of the landscape conservation area as a nature reserve, the state of Berlin conducted investigations on the bat fauna in the Tiefwerder Wiesen and Pichelswerder in 2007. Bats such as the greater mouse-eared bat (strictly protected according to the BArtSchV and listed in Annex II of the Fauna-Flora-Habitat-Richtlinie (FFH) (Habitats Directive); downgraded in Berlin 2003 from endangered to critically endangered) and the water bat (upgraded in Berlin 2003 from endangered to critically endangered) frequently use the Havel channel as a flight path and hunting ground. These nocturnal and highly social bats seek out the insect-rich Tiefwerder Wiesen for hunting, starting from their roosts in places like the Citadel or the old walls on Pfaueninsel.
Insects
Among the insects, the presence of the black cobwater beetle (Hydrophilus aterrimus) in the Tiefwerder is noteworthy, as it is highly endangered in Berlin. This heat-loving water beetle, strictly protected under the Bundesartenschutzverordnung (BNatSchG), strongly resembles the large water beetle, and prefers larger, mostly perennial waters in sunny areas. Although many waters are suitable for adult large beetles (length up to five centimeters), they are not suitable for their larvae. Especially the 1st and 2nd larval stages require extremely shallow, vegetated, and undisturbed shallow water areas. The young larvae, supported by plant growth, lift their food (small aquatic snails) out of the water to predigest it outside their body.
Several weevil species were last recorded in the Tiefwerder Wiesen in the 1980s and early 1990s. Since intensive searches did not yield any further findings, the small beetles (1.3–20 mm) are mostly considered lost in Berlin. Among them are the shore weevil (Ceutorhynchus scapularis; last record August 1985, one specimen), the hollow-toothed weevil (Datonychus angulosus; May 1990, four specimens), the suture-striped catkin weevil (Dorytomus hirtipennis; February 1991, fifteen specimens found in the bark scales of a silver willow), and the broad silky weevil (Smicronyx smreczynskii; June 1989, one specimen). The silt weevil (Pelenomus velaris), which prefers vegetation-free, periodically flooded, waterlogged sand and mud areas, and its developing plant is not known. It was recorded in Berlin for the first and last time in May 1990 with one specimen. In December 2003, a specimen of the brown-red willow weevil (Ellescus infirmus) was found for the first time on the sieve (soil sample) of a willow in the Tiefwerder Wiesen.
Other animals
The reedbeds of the Tiefwerder Wiesen are home to the grass frog, which is specially protected under the BNatSchG, but since a good population trend was noted as early as 1991, it is no longer classified as endangered on the current Berlin Red List of 2003. The grass snake, however, remains endangered in Berlin. It also finds its preferred habitat in the area: structurally rich wetlands, both aquatic and terrestrial.
Grey herons are a common sight as they linger in the meadows before their autumn migration south to feed. The Tiefwerder Wiesen also serves rare and endangered bird species as breeding, migratory, and wintering grounds. For example, the kingfisher, which is highly endangered in Berlin, can occasionally be seen. Due to its endangerment, this species, which is strictly protected under the BNatSchG, has already been voted Bird of the Year twice in Germany, in 1973 and 2009. The sedge meadows, reeds, and tall grasses are home to pond warbler, marsh warbler, dunnock, coot, and little grebe, among others. The bird of the year 1983, the sand martin, is also found in the Tiefwerder Wiesen. Its young birds congregate in large numbers on roosts in the reeds and willow thickets after leaving the breeding burrows.
Nature conservation and trails
Protected areas and maintenance measures
With the Ordinance for the Protection of Landscape Parts in the District of Spandau of Berlin, the Tieferwerder Wiesen has been designated as a Landschaftsschutz or LSG (protected landscape area). Today, it is listed as No.24 and it covers an area of 66.69 ha. Since 2007, the state has been considering raising its protection status as a nature reserve. Due to its proximity to the Tiefwerder waterworks, which supply drinking water to six Berlin districts, significant portions of the LSG are part of the narrower water protection zone II.
The Senate Department of Urban Development and Environmental Protection stated the target in the 1994 Landscape Program and Species Conservation Program:
The main focus of preservation and protection measures within the landscape conservation area is to maintain flood dynamics. This may involve artificial irrigation of the Tiefwerder Wiesen with Havel water and the construction of fish ladders if necessary. Another priority is preserving the softwood meadows, especially for the beaver population after removing dams, roads, arbors, and bank obstructions. Since 2014, regular maintenance mowing has stopped, and instead, a conservation approach using Asian water buffalo, sheep, and goats has been adopted to manage the meadows and conserve the ecosystem. These animals are protected and kept effective by enclosing the meadows with electric fences, preventing access by residents and visitors. Additionally, forestry measures are planned to develop the adjacent Pichelswerder forest into a near-natural mixed oak forest.
Road network and connection to Berlin's green corridors
A circular trail provides access to the central wetland. A plank footbridge about 200 meters long, built in 1996, leads through the wet meadows, while wooden bridges guide over several ditches and the Totes Mantel. An additional long footbridge over the Kleiner Jürgengraben connects the meadows with the Dorfstraße in Tiefwerder and two footpaths with the Heerstraße.
Towards the south, the area is linked to the Havel Heights Trail via Pichelswerder and the Grunewald, while to the east, it connects to the natural area of the Murellenberge and the Ruhleben flowing meadow at the Teltownord edge. In 2004, the Senate Department for Urban Development proposed an elevated path on the edge of the Teltownord as part of a plan for the western region of Berlin. This path would create an almost continuous green corridor, starting from the Tiefwerder Wiesen, passing via Charlottenburg Palace and the Großer Tiergarten to the western part of the city. In 2007, DB ProjektBau also completed the Bullengraben Green Corridor as a nature conservation compensation measure for the adverse effects on nature and the landscape caused by the construction project for the high-speed rail line between Hanover and Berlin. The Bullengraben green corridor runs about 4.5 kilometers west of Staaken along the Havel River. To further enhance the green corridor and connect it to Tiefwerder and the Tiefwerdre Wiesen, the Senate administration proposed the construction of a pedestrian footbridge across the river, as the Bullengraben green corridor meets the Havel only about one kilometer north of the village of Tiefwerder.
The Tiefwerder meadows in the Havel biotope network
The biotope network is recognized for its vital role in linking habitats for the conservation of endangered species and has been anchored as a new conservation goal in the Naturschutzgesetz or NSG (Nature Conservation Act). The Havel River and its continuity are of immense importance for migrating fish, as a flight path for bats, as a breeding, migration, and wintering area for birds, and as a migration route for beavers and otters. Recognizing its significance, Berlin's nature conservation associations included the Havel as a connecting landscape element in their list of proposals for the re-registration of protected areas under Article 10 of the European Fauna-Flora-Habitat Directive (FFH) for the state of Berlin in 2000. In Berlin alone, the Havel River links ten landscape protection areas and three nature conservation areas, including the Imchen Island near Kladow NSG, the Pfaueninsel NSG, and the Spandauer Forst LSG. Along its course, it connects existing FFH areas such as the Uckermärkische Seenlandschaft or the Tegeler Fließ, as well as designated SPA areas like the Havelländisches Luch or the lowlands of the lower Havel. Together with the adjacent luch landscapes such as Rhinluch, Havelländisches Luch, Dossebruch and Jäglitzniederung, the lower Havel lowlands form the largest contiguous inland wetland in western-Central Europe. Within this extensive biotope network, the centrally located Tiefwerder Wiesen plays a crucial role as an inner-city link and acts as a " stepping stone for crossing the urban area" for many species.
See also
Pichelswerder
Tiefwerder
References
Further reading
Biotoptypen- und FFH-Lebenraumtypenkartierung für das NSG Murellenschlucht und Schanzenwald, NSG Fließwiese Ruhleben und angrenzende Bereiche. Auftraggeber: Senatsverwaltung für Stadtentwicklung, Planland (Planungsgruppe Landschaftsentwicklung), Berlin 2006.
.
.
H. J. Mahnkopf: Tiefwerder – Hechtlaichwiesen. Der Hecht als „Umweltschützer“. In: Berliner Naturschutzblätter, Berlin 1988, Jg. 32, pp. 10–12.
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External links
Commons: Tiefwerder Wiesen - Collection of images, videos and audio files.
Landscape protection area Tiefwerder Wiesen. Senate Department for Urban Development.
Ordinance for the protection of parts of the landscape in the Spandau district of Berlin (Tiefwerder Wiesen). From September 12, 1960. Senate Department for Urban Development.
VDE 17 – A chance for the Tiefwerder meadows. Press release of the Federal Waterways and Shipping Administration, Waterways New Construction Office Berlin, June 26, 2008.
Havel basin
Spree basin
Endangered species
Charlottenburg
Floodplains of Europe | Tiefwerder Wiesen | [
"Biology"
] | 6,461 | [
"Biota by conservation status",
"Endangered species"
] |
74,483,424 | https://en.wikipedia.org/wiki/Hydration%20isomerism | In coordination chemistry, hydration isomerism is a kind of isomerism that is observed in some solids. Hydration isomers have identical formula but differ with respect to the numbers of water ligands.
Examples
One example is the pair . The former has one water of crystallization but the latter does not.
Another example is the pair of titanium(III) chlorides, . The former is violet and the latter, with two molecules of water of crystallization, is green.
References
Isomerism
Coordination chemistry | Hydration isomerism | [
"Chemistry"
] | 105 | [
"Isomerism",
"Stereochemistry",
"Coordination chemistry"
] |
74,484,291 | https://en.wikipedia.org/wiki/3-%28Difluoromethyl%29-1-methyl-1H-pyrazole-4-carboxylic%20acid | 3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid is a chemical compound which is used commercially as an intermediate to seven fungicides which act by inhibition of succinate dehydrogenase (SDHI). It consists of a pyrazole ring with difluoromethyl, methyl and carboxylic acid groups attached in specific positions.
Background
Inhibition of succinate dehydrogenase, the complex II in the mitochondrial respiration chain, has been known as a fungicidal mechanism of action since the first examples were marketed in the 1960s. By 2016, at least 18 examples were developed by crop protection companies, with the market leader being boscalid, owing to its broad spectrum of fungal species controlled. However, it lacked full control of important cereal diseases, especially septoria leaf blotch Zymoseptoria tritici.
A group of compounds which did control septoria were 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic amides, as shown below, ordered by year of their first registration.
Synthesis
The first reported synthesis of the pyrazole acid was in 1993, by chemists at Monsanto.
The ethyl ester of difluoroacetoacetic acid is treated with triethyl orthoformate in the presence of acetic anhydride and then with methyl hydrazine, which forms mainly the required pyrazole ring, in addition to its isomer with the methyl group on the alternative nitrogen atom. This ester is then hydrolysed with sodium hydroxide to give the pyrazole acid.
Manufacture of the acid at large scale has been optimised by chemists at Syngenta, Bayer Crop Science and BASF.
Uses
, amides of the acid were commercialised in seven SDHI fungicides. The US Geological Survey for 2018 reported that the most heavily used there were fluxapyroxad, at , followed by benzovindiflupyr at . The acid has been reported as a metabolite of fluxapyroxad and pydiflumetofen and thus may be present in the environment where these materials are used. The most recently registered example of this class is Sumitomo's inpyrfluxam. Two further compounds, pyrapropoyne (Nissan Chemical Corporation) and flubeneteram (Dongguan Hec Tech) are under development.
This group of pyrazole carboxamide fungicides are very effective against major crop pests such as Alternaria species, including early blight of tomato and potato. However, none display commercial levels of activity against oomycetes, fungal-related organisms which include important diseases like Phytophthora infestans, late blight of potato.
References
Difluoromethyl compounds
Pyrazoles
Carboxylic acids | 3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid | [
"Chemistry"
] | 624 | [
"Carboxylic acids",
"Functional groups"
] |
62,988,782 | https://en.wikipedia.org/wiki/Ekpoma%20virus | Ekpoma viruses, including Ekpoma 1 tibrovirus (EKV-1) and Ekpoma 2 tibrovirus (EKV-2), are orphan viruses not associated with any disease. They are negative-sense RNA viruses and members of the rhabdovirus family. Both viruses were discovered in 2015 in blood samples collected from two healthy women living in Ekpoma, Nigeria. EKV-2 appears to be widespread and ~45% of people living in and around Ekpoma have been previously exposed. Both viruses have very broad cellular tropism and the ability to infect a wide range of human cancer cell lines. Neither virus has been isolated, hindering research.
Discovery
EKV-1 and EKV-2 were discovered in plasma samples from a 45-year-old female and in a 19-year-old female, respectively. Neither woman presented with any indication of illness and according to a 2015 report, the samples were collected as controls in a larger metagenomics study. The viruses were identified using next-generation sequencing.
Clinical Disease
EKV-1 and EKV-2 are orphan viruses not associated with any disease. According to the 2015 report, the woman infected with EKV-1 could not recall any episode of illness in the weeks or months following the collection of her sample. The woman infected with EKV-2 recalled a fever that occurred several weeks after the sample collection. She was diagnosed and treated for malaria.
Viremia
The titers of viremia observed in the women ranged from 45,000 RNA copies/mL plasma (EKV-2) to 4.5 million RNA copies/mL plasma (EKV-1).
Prevalence
Researchers used an enzyme-linked immunosorbent assay (ELISA) to detect antibodies that recognize the nucleocapsid protein of EKV-1/2. They reported that 5% of people living in and around Ekpoma had been exposed to EKV-1 and 45% to EKV-2.
Transmission
The natural reservoir and mode of transmission for EKV-1/2 are not known. Based on the natural reservoir and vector for other tibroviruses, researchers have hypothesized that biting midges may transmit the viruses to humans.
Genome
The published genomes of EKV-1 and EKV-2 are not complete. However, based on the sequence available, the genome contains the typical five open reading frames present in all rhabdoviruses (N, P, M, G, and L). The viruses also include three open reading frames of unknown function (U1, U2 and U3). U3 has been hypothesized to be a viroporin based on sequence similarity to other viroporins.
Genetic divergence
Although EKV-1 and EKV-2 were discovered in the same village in southwestern Nigeria, they only share 33% overall homology at the amino acid level.
One notable difference between the two viruses is in the length of the phosphoprotein (P). The EKV-1 phosphoprotein contains 115 more amino acids than the EKV-2 phosphoprotein.
Also notable are the differences in the envelope glycoprotein. The EKV-1 and EKV-2 envelop glycoproteins are only 27% identical at the amino acid level.
Replication
The EKV-1 and EKV-2 cellular receptors have not been identified. However, tropism of EKV-1 and EKV-2 has been studied using recombinant vesicular stomatitis virus (VSV) that express the EKV-1 or EKV-2 glycoproteins. VSV particles that express the EKV-1 and EKV-2 glycoproteins outperform the native VSV glycoprotein. These particles are able to enter a wide range of human and non-human cells.
The steps in the replication lifecycle after particle entry have not be elucidated.
References
Rhabdoviridae
Unaccepted virus taxa | Ekpoma virus | [
"Biology"
] | 855 | [
"Biological hypotheses",
"Unaccepted virus taxa",
"Controversial taxa"
] |
62,989,733 | https://en.wikipedia.org/wiki/Dental%20cermet | Dental cermets, or silver cermets, are a type of restorative material dentists use to fill tooth cavities.
Silver cermets were created to improve the wear resistance and hardness of another type of filling material, glass ionomer cements, through the addition of silver. While the incorporation of silver achieved this, cermets have poorer aesthetics, appearing metallic rather than white. Cermets also have a similar compressive strength, flexural strength, and solubility as glass ionomer cements, some of the main limiting factors for both materials. Therefore, silver cermets are not a popular choice of restorative material.
Composition
Silver cermets can come in two forms:
Two bottles, one containing a powder and the other containing a liquid. The powder and liquid must be measured out individually and mixed together by hand.
A capsule in which the cermet components have already been proportioned correctly. The capsule is shaken in an amalgamator to mix the components.
The powder contains silver and fluoroaluminosilicate glass particles; the silver and glass particles may be fused together or separate. Other components in the powder include titanium oxide which acts as a whitening agent to improve aesthetics.
The liquid is an aqueous solution of a co-polymer of either 37% acrylic or maleic acid, or both, and 9% tartaric acid.
When the liquid and powder are mixed, an acid-base reaction occurs, initiating setting of the cermet.
Properties
Fluoride release
Like glass ionomer cements and dental compomers, silver cermets are able to release fluoride over a sustained period of time. However, the evidence suggests the fluoride releasing abilities of cermets are poorer than glass ionomer cements.
Adhesion
Cermets are able to bond to tooth tissue similar to glass ionomer cements. Like glass ionomer cements, it is recommended that the tooth tissue is conditioned with polyacrylic acid (a weak acid) before application.
Wear resistance
There is evidence that cermets have poor wear resistance when used to restore a large surface area. Therefore, it is advisable to limit their use to small restorations, particularly Class I cavities (see Green Vardiman Black Classification section on the Wiki page for Dental Restoration).
Radiopacity
The added silver imparts radio-opacity to cermets which aids radiographic detection of recurrent caries at a future date.
Clinical application
Silver cermets have performed poorly in clinical practice despite their theorised advantages over glass ionomer cements. As such, they are no longer a popular choice of material and it is unclear whether cermets will continue to be used.
Summary
References
Dental materials | Dental cermet | [
"Physics"
] | 579 | [
"Materials",
"Dental materials",
"Matter"
] |
62,989,815 | https://en.wikipedia.org/wiki/NGC%203664 | NGC 3664 is a magellanic barred spiral galaxy in the constellation of Leo. It is located about 80 million light years away from Earth, which means, given its apparent dimensions, that NGC 3664 is approximately 50,000 light years across. It was discovered by Wilhelm Tempel on March 14, 1879. It is a member of the NGC 3640 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.
The galaxy is characterised by its asymmetric shape, which features a single spiral arm and an off-centre bar. The distribution of HI is equally asymmetric.
Nearby galaxies
NGC 3664 has a smaller satellite galaxy, known as NGC 3664A or UGC 6418, which lies 6.2 arcminutes to the south, at a projected distance of 25 to 30 kiloparsecs from NGC 3664. The HI mass of NGC 3664A is , which means that the system has similar masses as the system of the Large and Small Magellanic Cloud. A HI bridge has been detected to connect the two galaxies in images obtained by the Very Large Array. The HI also appears warped at the side of NGC 3664 opposite of NGC 3664A, indicating an ongoing interaction. The bar of NGC 3664 could have developed due to this interaction.
NGC 3664 and its satellite belong to the NGC 3640 group, named after the galaxy NGC 3640. Other members of the galaxy group include NGC 3630, NGC 3641, and NGC 3643. The group belongs to the Leo II groups, a large collection of galaxies belonging to the Virgo Supercluster scattered across 30 million light years of space west of the Virgo Cluster.
See also
NGC 4027 - a similar spiral galaxy
References
External links
NGC 3664 on SIMBAD
Barred spiral galaxies
Peculiar galaxies
Interacting galaxies
Leo (constellation)
Discoveries by Wilhelm Tempel
Astronomical objects discovered in 1789
3664
06419
35041
005
Magellanic spiral galaxies | NGC 3664 | [
"Astronomy"
] | 423 | [
"Leo (constellation)",
"Constellations"
] |
62,990,925 | https://en.wikipedia.org/wiki/B%C3%A9la%20Paizs | Béla Paizs is a Hungarian bioinformatician.
His research interests revolve around fragmentation of peptides in mass spectrometry. In top-down proteomics, the interpretation of fragment ion spectra of peptides is a crucial step. The research of Béla Paizs have led to detailed characterization of peptide fragment ion structures and dissociation mechanisms, and have shown underlying fundamental physical and chemical principles. His work has been recognized with the American Society for Mass Spectrometry Biemann Medal in 2011.
Paizs received his Ph.D. in Chemistry in 1998 from Eötvös University in Budapest and graduated with summa cum laude honors. He worked as postdoctoral fellow there and later at the DKFZ in Heidelberg. He held a position as group leader since 2004 at the German Cancer Research Center in Heidelberg until 2013 when he moved to Bangor University.
References
21st-century chemists
Mass spectrometrists
Living people
Year of birth missing (living people) | Béla Paizs | [
"Physics",
"Chemistry"
] | 203 | [
"Biochemists",
"Mass spectrometry",
"Spectrum (physical sciences)",
"Mass spectrometrists"
] |
62,991,271 | https://en.wikipedia.org/wiki/Attention%20inequality | Attention inequality is the inequality of distribution of attention across users on social networks, people in general, and for scientific papers. Yun Family Foundation introduced "Attention Inequality Coefficient" as a measure of inequality in attention and arguments it by the close interconnection with wealth inequality.
Relationship to economic inequality
Attention inequality is related to economic inequality since attention is an economically scarce good. The same measures and concepts as in classical economy can be applied for attention economy. The relationship develops also beyond the conceptual level—considering the AIDA process, attention is the prerequisite for real monetary income on the Internet. On data of 2018, a significant relationship between likes and comments on Facebook to donations is proven for non-profit organizations.
Extent
As data of 2008 shows, 50% of the attention is concentrated on approximately 0.2% of all hostnames, and 80% on 5% of hostnames. The Gini coefficient of attention distribution lay in 2008 at over 0.921 for such commercial domains names as ac.jp and at 0.985 for .org-domains.
The Gini coefficient was measured on Twitter in 2016 for the number of followers as 0.9412, for the number of mentions as 0.9133, and for the number of retweets as 0.9034. For comparison, the world's income Gini coefficient was 0.68 in 2005 and 0.904 in 2018. More than 96% of all followers, 93% of the retweets, and 93% of all mentions are owned by 20% of Twitter.
Causes
At least for scientific papers, today's consensus states that inequality is unexplainable by variations of quality and individual talent. The Matthew effect plays a significant role in the emergence of attention inequality—those who already enjoy large amounts of attention get even more attention, and those who do not lose even more. Ranking algorithms based on relevance to the user have been found to alleviate the inequality of the number of posts across topics.
See also
Attention economy
Cumulative advantage
Cumulative inequality theory
Dominant narrative
Doomscrolling
Egotism
Empathy gap
Famous for being famous
Filter bubble
First World privilege
Kardashian index
Knowledge gap hypothesis
Law of triviality
Ortega hypothesis
Overconsumption
Pareto distribution
Privilege hazard
Rational expectations
Social invisibility
References
External links
Attention inequality by Yun Family Foundation
Social media
Attention
Popularity
Social influence
Social inequality
Cognitive biases
Economic inequality
Information Age
Matthew effect | Attention inequality | [
"Technology"
] | 491 | [
"Information Age",
"Computing and society",
"Social media"
] |
62,991,333 | https://en.wikipedia.org/wiki/Ferrophosphorus | Ferrophosphorus is a ferroalloy, an alloy of iron and phosphorus. It contains high proportion of iron phosphides, Fe2P and Fe3P. Its CAS number is 8049-19-2. The usual grades contain either 18 or 25% of phosphorus. It is a gray solid material with melting point between 1050-1100 °C. It may liberate phosphine in contact with water. Very fine powder can be combustible.
Ferrophosphorus is used in metallurgy as a source of phosphorus for alloying, for deoxidizing the melt and for removal of unwanted compounds into slag.
Ferrophosphorus is a byproduct of phosphorus production in submerged-arc furnaces from apatites, by their reduction with carbon. It is formed from the iron oxide impurities.
Addition of ferrophosphorus is used to produce powder metallurgy (P/M) steels with favorable magnetic properties, e.g. high saturation induction. Iron phosphide acts here as a solid solution hardener and a sintering aid. Usually about 0.45 w/o of phosphorus is added to iron; higher amount can improve magnetic properties but at above about 0.8 w/o the process parameters have to be too tightly controlled to prevent phosphorus segregation on grain boundaries and resulting excessive brittleness.
Ferrophosphorus can be added to cast iron, where the phosphorus improves fluidity and therefore quality of the castings, can increase wear resistance and cutability. In steels its addition to some alloys can improve corrosion resistance.
Ferrophosphorus can be used as a construction aggregate for production of high-density concrete for radiation shielding, as an alternative to usually used steel punchings and shot. It can be used with both Portland cement and magnesia cement.
Ferrophosphorus, reacted with sulfur or pyrite, is used for production of phosphorus pentasulfide.
Ferrophosphorus can be used for production of lithium iron phosphate, necessary as electrode material for LiFePO4 batteries.
Ferrophosphorus can be used instead of zinc powder in some paints and coatings. It has good adhesion, anticorrosive properties, electrical and thermal conductivity, and wear resistance.
Ferrophosphorus can be used as a reducing agent to produce sodium or potassium from sodium carbonate or potassium carbonate.
References
Ferroalloys
Iron
Deoxidizers
Iron compounds
Phosphides | Ferrophosphorus | [
"Chemistry",
"Materials_science"
] | 523 | [
"Deoxidizers",
"Metallurgy"
] |
62,991,617 | https://en.wikipedia.org/wiki/Nazanin%20Bassiri-Gharb | Nazanin Bassiri-Gharb is a mechanical engineer in the field of micro and nano engineering and mechanics of materials. She is the Harris Saunders, Jr. Chair and Professor in the George W. Woodruff School of Mechanical Engineering at the Georgia Institute of Technology in Atlanta, Georgia. Bassiri-Gharb leads the Smart Materials, Advanced Research and Technology (SMART) Laboratory at Georgia Tech. Her research seeks to characterize and optimize the optical and electric response of interferometric modulator (IMOD) displays. She also investigates novel materials to improve reliability and processing of IMOD.
Education
Bassiri-Gharb obtained her Laurea Degree from the University of Padua in Italy in 2001. She graduated with a Doctorate of Philosophy in Materials Science and Engineering from Pennsylvania State University in 2005. Her thesis was entitled Dielectric and Piezoelectric Nonlinearities in Oriented Pb(Yb1/2Nb1/2)03-PbTiO3 Thin Films.
Career
Research interests
Bassiri-Gharb is interested in applying ferroelectric and multiferroic materials to micro- and nano- electromechanical systems. She is also interested in using these materials to develop novel sensors and actuators for the fields of environmental energy harvesting, tunable photonic crystals, and ultrasonic transducers. Additionally, Bassiri-Gharb researches peizoelectric MEMS devices to manipulate nanoscale materials.
Professional societies
Institute of Electrical and Electronics Engineers - Ultrasonics, Ferroelectrics, and Frequency Control Society (IEEE UFFC-S)
Institute of Electrical and Electronics Engineers (IEEE)- Women in Engineering
Society of Women Engineers
Professional committees
Bassiri-Gharb has sat and sits on several professional committees.
Scientific Reports, Editorial Board: 2014–present
IEEE UFFC-S, President: 2018-2019
IEEE UFFC-S, President-Elect: 2016-2017
IEEE UFFC-S, Newsletter Editor-in-Chief: 2012-2013
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Associate Editor: 2011–present
IEEE Nanotechnology Council, AdCom Representative: 2008-2013
IEEE Women in Engineering, Society Liaison: 2008-2013
IEEE Educational Committee Officer: 2006–present
Journal of Electroceramics, Editorial Board, 2007–present
Awards and patents
Awards
IEEE-Ultrasonics, Ferroelectrics and Frequency Control (UFFC) Ferroelectrics Young Investigator Award, 2013
NSF Career Award, 2013
Georgia Institute of Technology, Class of 1969 Teaching Fellow, 2012
Bennett Aerospace, Researcher of the year award, 2011
Patents
Soft Template Manufacturing of Nanomaterials, U.S. Patent 20130149500A1 with A. Bernal, 2011
References
Living people
Year of birth missing (living people)
University of Padua alumni
Penn State College of Engineering alumni
Georgia Tech faculty
Mechanical engineers | Nazanin Bassiri-Gharb | [
"Engineering"
] | 597 | [
"Mechanical engineers",
"Mechanical engineering"
] |
62,991,864 | https://en.wikipedia.org/wiki/NGC%202227 | NGC 2227 is a barred spiral galaxy with a morphological type of SB(rs)c located in the direction of the Canis Major constellation. It was discovered on January 27, 1835, by John Herschel.
One supernova has been observed in NGC 2227: SN1986O (typeIa, mag. 14) was discovered by Carlton Pennypacker et al. on 24 December 1986.
See also
Extragalactic astronomy
List of galaxies
New General Catalogue
References
External links
Catalog of NGC 2227
NGC 2227 – SEDS.org (Revised NGC)
Deep Sky Browser – NGC2227
VizieR Service
Aladin previewer – image
Imagem de NGC2227 – SkyView
Barred spiral galaxies
Canis Major
2227
019030 | NGC 2227 | [
"Astronomy"
] | 152 | [
"Canis Major",
"Constellations"
] |
62,993,355 | https://en.wikipedia.org/wiki/Peanut%20allergen%20powder | Peanut allergen powder, sold under the brand name Palforzia, is an oral medication used for the treatment of children who have confirmed cases of peanut allergy. It is taken by mouth.
Peanut allergen powder is a powder that is manufactured from peanuts (Arachis hypogaea) and packaged in pull-apart color-coded capsules for dose escalation and up-dosing, and in a sachet for maintenance treatment.
The most common side effects of peanut allergen powder are abdominal pain, vomiting, nausea, tingling in the mouth, itching (including in the mouth and ears), cough, runny nose, throat irritation and tightness, hives, wheezing and shortness of breath and anaphylaxis. Peanut allergen powder should not be administered to those with uncontrolled asthma.
In January 2020, the FDA approved the drug to Aimmune Therapeutics for mitigating "allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanuts." It is the first drug approved for treating peanut allergies.
Medical uses
In the United States, peanut allergen powder is indicated for the mitigation of allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanut.
In the European Union, peanut allergen powder is indicated for the treatment of people aged 4 to 17 years of age with a confirmed diagnosis of peanut allergy.
History
The effectiveness of peanut allergen powder is supported by a randomized, double-blind, placebo-controlled study conducted in the US, Canada, and Europe in approximately 500 peanut-allergic individuals. Effectiveness was assessed by evaluating the percentage of study participants tolerating an oral challenge with a single 600 mg dose of peanut protein (twice the daily maintenance dose of peanut allergen powder) with no more than mild allergic symptoms after six months of maintenance treatment. The results showed that 67.2% of peanut allergen powder recipients tolerated a 600 mg dose of peanut protein in the challenge, compared to 4.0% of placebo recipients. The safety of peanut allergen powder was assessed in two double-blind, placebo-controlled studies in approximately 700 peanut-allergic individuals.
In December 2018, Aimmune Therapeutics applied Biologics License Application for peanut allergen powder-dnfp to the US Food and Drug Administration. In September 2019, the FDA Allergenic Products Advisory Committee decided seven to two in favor of the approval. The final approval was issued in January 2020.
Society and culture
Legal status
Peanut allergen powder was approved for medical use in the United States in January 2020, and in the European Union in December 2020.
The US Food and Drug Administration (FDA) requires a risk evaluation and mitigation strategy (REMS). Peanut allergen powder is only available through specially certified healthcare providers, health care settings, and pharmacies to those who are enrolled in the REMS program.
In October 2020, the Committee for Medicinal Products for Human Use of the European Medicines Agency adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Palforzia, intended for desensitizing children and adolescents to peanut allergy. It was approved for medical use in the European Union in December 2020.
Controversy
Although the US Food and Drug Administration (FDA) had decided the approval of peanut allergen powder in 2019, the Institute for Clinical and Economic Review (ICER) reported that the clinical evidence is still insufficient. A 2019 systematic review and meta-analysis of twelve clinical trials consisting of 1041 cases questioned the safety of oral peanut allergen treatment. The study concluded that the treatments "increase allergic and anaphylactic reactions over avoidance or placebo, despite effectively inducing desensitisation."
References
Further reading
Allergy, peanuts
Food allergies
Immunotherapy
Powders | Peanut allergen powder | [
"Physics"
] | 802 | [
"Materials",
"Powders",
"Matter"
] |
62,994,633 | https://en.wikipedia.org/wiki/EthioTrees | The EthioTrees Ecosystem Restoration Association, in short EthioTrees, established in 2016, is a project for environmental rehabilitation and woodland restoration in Dogu’a Tembien (Ethiopia).
Context
For many years, there has been severe land degradation and desertification in Tigray and the area became also impoverished; however, a lot of efforts are done to rehabilitate these semi-arid mountain landscapes. Since 1994, researchers, students, and field assistants have studied the environment of Dogu’a Tembien. To contribute to the ongoing effort for rehabilitation, they initiated development projects that addressed in the first place land conservation, ecosystem services, and livelihood. EthioTrees is one of these projects.
Objectives
EthioTrees has as objectives:
to enhance community-driven woodland restoration in exclosures
to sequester carbon in exclosures, both as above-ground biomass and soil organic matter
to develop and valorise ecosystem services, including:
* ground water availability
* honey production
* incense (oil) production
Associations of landless farmers
EthioTrees not only improves soil organic carbon, biomass, groundwater recharge, or biodiversity but also cash income for landless farmers. Most farmers estimate that lack of access to water is the main problem for their livelihood. In addition, landless youngsters derive much less income from sales of livestock or agricultural produce, in comparison to farmers with land. The communities are invited to design and implement the project themselves; for this purpose, EthioTrees uses a participatory mapping approach during all phases of the project.
EthioTrees’ exclosures
The EthioTrees project manages these exclosures:
Addi Lihtsi, near the village of Addi Lihtsi (412 ha)
Addi Meles, near the village of Migichi (65 ha)
Addilal, near the village of Addilal (144.81 ha)
Afedena, near the village of Afedena (70 ha)
Ch'elaqo, near the village of Ch'elaqo (50 ha)
Gemgema, near the village of Tsigaba (92 ha)
Kidmi Gestet, near the village of Gestet (46 ha)
Lafa, near the village of Lafa in Mizane Birhan municipality (45.25 ha)
May Be'ati, near the village of May Be'ati (46 ha)
Mi'am Atali, near the village of Mi'am Atali (83 ha)
May Genet, near the village of May Genet (60 ha)
May Hib'o, near the village of Addi Lihtsi (50 ha)
Sesemat, near the village of Tahtay Sesemat (46 ha)
Togogwa, near the village of Togogwa (196 ha)
Tukhul, near the village of Tukhul, in Addi Azmera municipality (36 ha)
Ziban Dake, near the village of Didiben (300 ha)
Gojam Sfra, near the village of Migichi (275 ha)
Katina Ruba, near the village of Didiben (48 ha)
Ecosystem restoration and valorisation
EthioTrees manages 18 exclosures with a total area of 1174 hectares in 2017 and 1596 ha in 2018. The older the exclosures, the higher is the total carbon content in vegetation and soil. EthioTrees has calculated that they manage to sequester 9.2 tonnes CO2 per year per hectare.
Carbon offset
The sequestered carbon is certified using the Plan Vivo voluntary carbon standard, after which carbon credits are sold, among others to Davines, an Italian producer of beauty products. This company at the same time wishes to create a virtuous impact on people and the environment. The revenues are then reinvested in the villages, according to the priorities of the communities; it may be for an additional class in the village school, a water pond, conservation in the exclosures, or a store for incense.
Partners
Main partners of Ethiotrees are
Dogu’a Tembien District Administration (Ethiopia)
Municipal administrations (Ethiopia)
Incense producing cooperatives (Ethiopia)
Plan Vivo (U.K.)
Mekelle University (Ethiopia)
VLIR-UOS (Belgium)
Davines (Italy)
Ghent University (Belgium)
Province East Flanders (Belgium)
King Baudouin Foundation (Belgium)
Bos Plus (Belgium)
Province West Flanders (Belgium)
Ñangareko Consultores (Bolivia)
Association Tesfay (Liége, Belgium)
References
External links
EthioTrees on Davines website
EthioTrees project website
EthioTrees on Plan Vivo website
Link For Forestry Projects
Land management
Environmental conservation
Greenhouse gas emissions
Emissions reduction
Carbon finance
2016 establishments in Ethiopia
Tigray Region
Dogu'a Tembien
Nature conservation in Ethiopia
Exclosures of Tigray Region | EthioTrees | [
"Chemistry"
] | 1,042 | [
"Greenhouse gases",
"Greenhouse gas emissions",
"Emissions reduction"
] |
62,996,604 | https://en.wikipedia.org/wiki/Econyl | Econyl regenerated nylon is a material and a brand introduced in 2011 by Aquafil. It is made entirely from waste otherwise polluting the Earth, such as industrial discards, fabric scraps from clothing manufacturing companies, old carpets and fishing nets (mainly from the aquaculture industry). The material has been used by Stella McCartney (handbag linings, backpacks, outerware, etc.), Kelly Slater's label Outerknown, Adidas and Speedo swimwear, Levi's, Breitling (watch straps), and many other brands from the fashion and interior industries.
Aquafil began nylon recycling in the 1990s, but did not begin exploration of a comprehensive nylon reuse cycle until 2007, which ultimately led to the development of Econyl Regeneration System and the associated closed-loop process in 2011.
For every 10,000 tons of Econyl raw material, it is possible to save 70,000 barrels of crude oil . Further, the material can be continuously recycled without loss of quality.
Aquafil facilities for the collection and recycling of nylon materials include a carpet recycling plant in the United States (in Phoenix, Arizona). Recycling involves breaking down the nylon polymer into monomers, and then re-polymerizing the nylon them into brend-new nylon; the breakdown process is done with temperature, steam and catalysts, in a renewable energy-driven process.
References
Further reading
External links
Synthetic fibers | Econyl | [
"Chemistry"
] | 297 | [
"Synthetic materials",
"Synthetic fibers"
] |
62,997,637 | https://en.wikipedia.org/wiki/ASIL%20accuracy | ASIL accuracy describes the maximum possible deviation of a measurement in a system in which a single point fault occurred before some diagnostic detects this fault. This concept applies to automotive systems designed under the ISO-26262 methodology for automotive functional safety, which defines Automotive Safety Integrity Levels (ASILs) to classify risks.
While accuracy refers to a single measurement, ASIL accuracy considers variation in the primary measurement being assessed as well as variation in the diagnostic measurement or measurements used to detect single point faults.
How to calculate
A conceptually simple implementation incorporates a fully redundant measurement. A fault in the primary measurement can be detected by comparing the primary and diagnostic measurements, and signaling a fault if the difference is outside the expected operating range. If the two measurements are truly independent and uncorrelated, in normal operation they can be at opposite ends of their operating ranges. If the primary measurement has an accuracy V1, and if the redundant diagnostic measurement has an accuracy V2, then the fault detection limit should be set to at least VLIM=V1+V2 to avoid false positives. The system shall flag a fault if the difference between V1 and V2 is greater than VLIM. The fault detection limit, however, should not be confused with ASIL accuracy. Consider the case of a single point fault in which the primary measurement drifts to an incorrect value. ASIL accuracy describes the maximum such drift before the fault is flagged. If the diagnostic measurement V2 is at the maximum of its operating range, the primary measurement can drift VLIM further before the fault is raised. The maximum possible drift in the primary measurement V1, then, is V2+VLIM, and so the ASIL accuracy VASIL=V2+VLIM.
References
Automotive engineering | ASIL accuracy | [
"Engineering"
] | 359 | [
"Automotive engineering",
"Mechanical engineering by discipline"
] |
62,998,740 | https://en.wikipedia.org/wiki/2MASS%20J11011926%E2%88%927732383 | 2MASS J11011926–7732383 AB (abbreviated 2M1101AB; LUH 1) is a brown dwarf binary about 600 light-years distant in the Chamaeleon. constellation. The wide binary pair is separated by about 240 astronomical units. The system was the first discovery of a brown dwarf binary with a separation greater than 20 au. The discovery gave fundamental insights into the formation of brown dwarfs. Previously it was thought that such wide binary brown dwarfs are not formed or at least are disrupted at ages of 1-10 Myrs. Together with other wide binaries, such as Oph 162225-240515 or UScoCTIO 108, the existence of this system was inconsistent with the ejection hypothesis, a proposed hypothesis in which brown dwarfs form in a multiple system, but are ejected before they gain enough mass to burn hydrogen. The ejection hypothesis predicted a maximum separation of 10 au for brown dwarf binaries.
The system was discovered by Kevin Luhman in 2004 during observations of candidate young brown dwarfs in Chamaeleon I, using the Magellan I telescope.
The primary 2M1101A has a spectral type of M7.25 ± 0.25, with a mass of about 52 and a temperature of 2838 K (2565 °C; 4649 °F). The secondary 2M1101B has a spectral type of M8.25 ± 0.25, with a mass of about 26 and a temperature of 2632 K (2359 °C; 4279 °F). Based on spectral features, such as sodium and potassium absorption lines it was concluded that both brown dwarfs are young and part of Chamaeleon I. The brown dwarfs in 2M1101AB belong to the youngest substellar members of Chamaeleon I with an approximate age of 1 million years. Measurements by ESA's Gaia satellite show a similar parallax and proper motion for both brown dwarfs. The system has a relatively low binding energy of ergs.
The system was detected in x-rays with Chandra and XMM-Newton. While XMM-Newton could not resolve the binary it detected the primary. Chandra resolved the binary and detected the secondary in the system. These apparently contradictory results were interpreted as strong variability of the x-ray emissions by this system.
See also
SDSS J1416+1348
UScoCTIO 108
Oph 162225-240515
Binary brown dwarfs
W2150AB
References
Astronomical objects discovered in 2004
Chamaeleon
Brown dwarfs
Binary stars
J11011926–7732383
M-type brown dwarfs | 2MASS J11011926−7732383 | [
"Astronomy"
] | 535 | [
"Chamaeleon",
"Constellations"
] |
71,644,793 | https://en.wikipedia.org/wiki/NGC%201624-2 | NGC 1624-2 is a massive O-type star located in the star cluster NGC 1624, in the constellation of Perseus, about 16,800 light years away. NGC 1624-2 is notable for being most strongly magnetised O-type star known, with a magnetic field strength of 20 kG, or about 20,000 times the Sun's magnetic field strength. It hosts a large and dense magnetosphere, formed from the interaction between its very strong magnetic field and its dense, radiatively-driven stellar wind, which also absorbs up to 95% of x-rays generated from around the star.
Properties
NGC 1624-2 is a very massive, young, blue star no more than 4 million years old. It is an Of?p star a type of highly magnetic star that has unusual emission lines of multiply-ionized carbon and nitrogen. In NGC 1624-2, the carbon emission is particularly extreme. The luminosity class is uncertain because of the unusual spectrum; it is most commonly given as V (main sequence), but has also been given as I (supergiant).
Analysis of its spectral energy distribution with CHORIZOS modelling yields an effective temperature of 35,000 K, a luminosity of (105.1 L☉) and a radius of about . Assuming a log g of 4.0 yields a mass of , but evolutionary models tend towards a current mass of , given the results from the modelling. However, this assumes that NGC 1624-2 is a normal star, while it is not, so it should only be taken as an indication of its true mass. NGC 1624-2 is currently losing mass at a rate of /year, through a stellar wind with a terminal velocity of 2,875 km/s.
Rotation
NGC 1624-2 rotates very slowly, only once every 316 days. This slow rotation is typical for very magnetic O-type stars as their magnetic fields slow down their rotation in a process known as magnetic braking, where angular momentum is quickly shed by the stellar wind via the strong magnetic field, which also minimises mass loss throughout the main sequence.
References
O-type main-sequence stars
Perseus (constellation)
J04403728+5027410 | NGC 1624-2 | [
"Astronomy"
] | 458 | [
"Perseus (constellation)",
"Constellations"
] |
71,645,045 | https://en.wikipedia.org/wiki/Joseph%20Melia | Joseph Melia is a philosopher working in the areas of philosophy of mathematics, modal logic and possible worlds. He has made important contributions to the debate over the Quine–Putnam indispensability argument, where he argues for a "weaseling" approach to mathematical nominalism. He has also argued against modalism and the modal realism of David Lewis.
References
Philosophers of mathematics
20th-century British philosophers
Year of birth missing (living people)
Living people
21st-century British philosophers | Joseph Melia | [
"Mathematics"
] | 101 | [
"Philosophers of mathematics"
] |
71,645,454 | https://en.wikipedia.org/wiki/International%20Methane%20Emissions%20Observatory | The International Methane Emissions Observatory (IMEO) of the UN Environment Programme is an initiative which tackles the problem of methane emissions by collecting, integrating, and reconciling methane data from different sources, including scientific measurement studies, satellites, industry reporting through the Oil and Gas Methane Partnership 2.0, and national inventories. It was presented by the United Nations Environment Programme (UNEP) at the G20 Leaders' Summit in 2021. IMEO creates a public global dataset of empirically verified methane emissions, with an initial focus on fossil fuel sources, and interconnects this data with actions on research, reporting, and regulation. Manfredi Caltagirone is the Head of IMEO since its creation.
IMEO serves as an implementing vehicle for the Global Methane Pledge and has the European Commission as one of its founding members.
Methane emissions
Methane is an important greenhouse gas, and its atmospheric concentration has nearly tripled since pre-industrial times. It is responsible for about a quarter of current anthropogenic climate warming. Its relatively short atmospheric lifespan – 10 to 12 years – means that reducing methane emissions can yield near-term reductions in the rate of warming, as well as air quality benefits. In its special report in 2019, the Intergovernmental Panel on Climate Change (IPCC) noted that deep reductions in methane emissions must be achieved by 2030 to limit warming to 1.5 or even 2 degrees. Building upon this conclusion, in 2021 the IPCC highlighted in the IPCC 6th Assessment report the important role of methane and other short-lived climate pollutants, recognizing robust evidence that drastic cuts in methane are important for near-term climate benefits, improved air quality, and achieving the Paris Agreement temperature targets. The fossil fuel industry is responsible for an estimated one-third of anthropogenic methane emissions and is the sector with the highest potential for rapid and cost-effective reductions, slowing the rate of warming in the near term even as decarbonisation of the global energy system progresses.
An Eye On Methane
In October 2021, IMEO published its first annual report: "An Eye on Methane: International Methane Emissions Observatory 2021 Report". It describes how state actors can take action to curb methane emissions from the fossil fuel industry, and what progress has been made as part of the decarbonization process, particularly in the energy sector. The document provided a framework of action to track and monitor methane emissions to plan mitigation action.
Core functions
Core functions are:
Integrate methane data from all available sources into a platform, accounting for the confidence of each data element, that improves the characterization of global methane emissions.
Collate proprietary asset emissions data through OGMP 2.0, report aggregated company data and verify progress towards announced targets using a range of data sources.
Hold companies accountable for their emission performance and encourage companies to increase their performance targets, making rigorous methane emissions management integral to their operational practices.
Fund scientific measurement studies to improve the characterization of methane emissions from human activities globally.
Evaluate measurement methodologies and technologies to encourage the adoption at scale.
Engage countries through capacity building by developing policy-relevant science, strengthening the science-policy interface, and deepening the understanding of the climate importance of methane mitigation.
Provide early warning services for extraordinary anthropogenic methane emissions.
References
External links
United Nations Environment Programme - Methane
Global Methane Pledge
OGMP 2.0
Methane
United Nations Environment Programme | International Methane Emissions Observatory | [
"Chemistry"
] | 690 | [
"Greenhouse gases",
"Methane"
] |
71,645,948 | https://en.wikipedia.org/wiki/Code%20property%20graph | In computer science, a code property graph (CPG) is a computer program representation that captures syntactic structure, control flow, and data dependencies in a property graph. The concept was originally introduced to identify security vulnerabilities in C and C++ system code, but has since been employed to analyze web applications, cloud deployments, and smart contracts. Beyond vulnerability discovery, code property graphs find applications in code clone detection, attack-surface detection, exploit generation, measuring code testability, and backporting of security patches.
Definition
A code property graph of a program is a graph representation of the program obtained by merging its abstract syntax trees (AST), control-flow graphs (CFG) and program dependence graphs (PDG) at statement and predicate nodes. The resulting graph is a property graph, which is the underlying graph model of graph databases such as Neo4j, JanusGraph and OrientDB where data is stored in the nodes and edges as key-value pairs. In effect, code property graphs can be stored in graph databases and queried using graph query languages.
Example
Consider the function of a C program:
void foo() {
int x = source();
if (x < MAX) {
int y = 2 * x;
sink(y);
}
}
The code property graph of the function is obtained by merging its abstract syntax tree, control-flow graph, and program dependence graph at statements and predicates as seen in the following figure:
Implementations
Joern CPG. The original code property graph was implemented for C/C++ in 2013 at University of Göttingen as part of the open-source code analysis tool Joern. This original version has been discontinued and superseded by the open-source Joern Project, which provides a formal code property graph specification applicable to multiple programming languages. The project provides code property graph generators for C/C++, Java, Java bytecode, Kotlin, Python, JavaScript, TypeScript, LLVM bitcode, and x86 binaries (via the Ghidra disassembler).
Plume CPG. Developed at Stellenbosch University in 2020 and sponsored by Amazon Science, the open-source Plume project provides a code property graph for Java bytecode compatible with the code property graph specification provided by the Joern project. The two projects merged in 2021.
Fraunhofer AISEC CPG. The provides open-source code property graph generators for C/C++, Java, Golang, Python, TypeScript and LLVM-IR. It also includes a formal specification of the graph and its various node types. Furthermore, it provides the Cloud Property Graph, an extension of the code property graph concept that models details of cloud deployments.
Galois’ CPG for LLVM. Galois Inc. provides a code property graph based on the LLVM compiler. The graph represents code at different stages of the compilation and a mapping between these representations. It follows a custom schema that is defined in its documentation.
Machine learning on code property graphs
Code property graphs provide the basis for several machine-learning-based approaches to vulnerability discovery. In particular, graph neural networks (GNN) have been employed to derive vulnerability detectors.
See also
Abstract syntax tree (AST)
Control-flow graph (CFG)
Program dependence graph (PDG)
Graph database
References
Computer security software
Application-specific graphs | Code property graph | [
"Engineering"
] | 701 | [
"Cybersecurity engineering",
"Computer security software"
] |
71,646,030 | https://en.wikipedia.org/wiki/Tamara%20Loos | Tamara Loos is an American historian and gender studies scholar at Cornell University.
Biography
Tamara Loos is Professor of Southeast Asian history at Cornell University and has served as Chair of the History Department and Director of the Southeast Asia Program. Her first book, Subject Siam: Family, Law, and Colonial Modernity in Thailand, explores the implications of Siam's position as both a colonized and colonizing power in Southeast Asia. It is the first study that integrates the Malay Muslim south and the gendered core of law into Thai history. Her most recent book, Bones Around My Neck, offers a critical history of Siam during the era of high colonialism through the dramatic and tragic life of a pariah prince, Prisdang Chumsai. Her teaching and articles focus on an array of topics including sex and politics, subversion and foreign policy, sexology, transnational sexualities, comparative law, sodomy, and gender in Asia. She has been interviewed by The New York Times, The Washington Post, The Financial Times, and other global media outlets about political protests in Thailand.
Radio interviews
NPR: Thai Palace Officials Ousted Following Demotion Of Royal Consort
BBC: The Inquiry: Why are Thai students risking jail to call for reform of the monarchy?
Background Briefing with Ian Masters: Turmoil In Thailand As Subjects Question the King's Excesses and Entitlement
Selected publications
References
21st-century American historians
Historians of Southeast Asia
Historians of Thailand
Historians of sexuality
Cornell University Department of History faculty
Cornell University alumni
Pomona College alumni
21st-century American women writers
Living people
Year of birth missing (living people) | Tamara Loos | [
"Biology"
] | 323 | [
"Behavior",
"Sexuality",
"Historians of sexuality"
] |
71,649,659 | https://en.wikipedia.org/wiki/FARSIDE%20telescope | FARSIDE (Farside Array for Radio Science Investigations of the Dark Ages and Exoplanets) is a concept for a low-frequency interferometric array that would be placed on the farside of the Moon.
FarView
FarView is another concept for a 20x20 km radio observatory with a total collecting area of 400 kilometers that would also be located on the Moon's far side.
References
Proposed telescopes
Telescopes | FARSIDE telescope | [
"Astronomy"
] | 86 | [
"Telescopes",
"Astronomical instruments"
] |
71,649,685 | https://en.wikipedia.org/wiki/L%C3%A1szl%C3%B3%20Szebell%C3%A9dy | László Szebellédy (20 April 1901 – 23 January 1944) was a Hungarian chemist who contributed to electrochemistry with the development of Coulometric analytical techniques for detecting small quantities of chemicals with precision. He served as a professor at the Pázmány Péter University.
Szebellédy was born in Rétság and went to the Pázmány Péter University where he studied pharmacy, and obtained a doctorate in 1926. He then joined as an assistant to Professor Lajos Winkler (1863–1939). In 1933 he became an assistant professor. He went to Zurich, Dresden and Leipzig, working at the laboratories of W. D. Treadwell, Max Le Blanc (1865-1943) and Wilhelm Böttger (1871–1949). In 1935-36 he taught chemical analysis and worked on microanalysis techniques involving dyes, fluorescence, indicators and catalysts. He developed coulombetric (or coulometric) titration analysis along with Zoltan Somogyi (1915–1945) in 1938 where the volume of a chemical could be calculated using Faraday's laws. He died at the age of 43, publishing more than a hundred papers.
References
1901 births
1944 deaths
Electrochemists
Hungarian chemists | László Szebellédy | [
"Chemistry"
] | 253 | [
"Electrochemistry",
"Electrochemists"
] |
71,651,194 | https://en.wikipedia.org/wiki/Silver%27s%20dichotomy | In descriptive set theory, a branch of mathematics, Silver's dichotomy (also known as Silver's theorem) is a statement about equivalence relations, named after Jack Silver.
Statement and history
A relation is said to be coanalytic if its complement is an analytic set. Silver's dichotomy is a statement about the equivalence classes of a coanalytic equivalence relation, stating any coanalytic equivalence relation either has countably many equivalence classes, or else there is a perfect set of reals that are each incomparable to each other. In the latter case, there must be continuum many equivalence classes of the relation.
The first published proof of Silver's dichotomy was by Jack Silver, appearing in 1980 in order to answer a question posed by Harvey Friedman. One application of Silver's dichotomy appearing in recursive set theory is since equality restricted to a set is coanalytic, there is no Borel equivalence relation such that , where denotes Borel equivalence relation. Some later results motivated by Silver's dichotomy founded a new field known as invariant descriptive set theory, which studies definable equivalence relations. Silver's dichotomy also admits several weaker recursive versions, which have been compared in strength with subsystems of second-order arithmetic from reverse mathematics, while Silver's dichotomy itself is provably equivalent to over .
References
Set theory | Silver's dichotomy | [
"Mathematics"
] | 295 | [
"Mathematical logic",
"Set theory"
] |
71,652,129 | https://en.wikipedia.org/wiki/Weak%20stability%20boundary | Weak stability boundary (WSB), including low-energy transfer, is a concept introduced by Edward Belbruno in 1987. The concept explained how a spacecraft could change orbits using very little fuel.
Weak stability boundary is defined for the three-body problem. This problem considers the motion of a particle P of negligible mass moving with respect to two larger bodies, P1, P2, modeled as point masses, where these bodies move in circular or elliptical orbits with respect to each other, and P2 is smaller than P1.
The force between the three bodies is the classical Newtonian gravitational force. For example, P1 is the Earth, P2 is the Moon and P is a spacecraft; or P1 is the Sun, P2 is Jupiter and P is a comet, etc. This model is called the restricted three-body problem. The weak stability boundary defines a region about P2 where P is temporarily captured. This region is in position-velocity space. Capture means that the Kepler energy between P and P2 is negative. This is also called weak capture.
Background
This boundary was defined for the first time by Edward Belbruno of Princeton University in 1987. He described a Low-energy transfer which would allow a spacecraft to change orbits using very little fuel. It was for motion about Moon (P2) with P1 = Earth. It is defined algorithmically by monitoring cycling motion of P about the Moon and finding the region where cycling motion transitions between stable and unstable after one cycle. Stable motion means P can completely cycle about the Moon for one cycle relative to a reference section, starting in weak capture. P needs to return to the reference section with negative Kepler energy. Otherwise, the motion is called unstable, where P does not return to the reference section within one cycle or if it returns, it has non-negative Kepler energy.
The set of all transition points about the Moon comprises the weak stability boundary, . The motion of is sensitive or chaotic as it moves about the Moon within . A mathematical proof that the motion within is chaotic was given in 2004. This is accomplished by showing that the set about an arbitrary body P2 in the restricted three-body problem contains a hyperbolic invariant set of fractional dimension consisting of the infinitely many intersections Hyperbolic manifolds.
The weak stability boundary was originally referred to as the fuzzy boundary. This term was used since the transition between capture and escape defined in the algorithm is not well defined and limited by the numerical accuracy. This defines a "fuzzy" location for the transition points. It is also due the inherent chaos in the motion of P near the transition points. It can be thought of as a fuzzy chaos region. As is described in an article in Discover magazine, the WSB can be roughly viewed as the fuzzy edge of a region, referred to as a gravity well, about a body (the Moon), where its force of gravity becomes small enough to be dominated by force of gravity of another body (the Earth) and the motion there is chaotic.
A much more general algorithm defining was given in 2007. It defines relative to -cycles, where = 1,2,3,..., yielding boundaries of order n. This gives a much more complex region consisting of the union of all the weak stability boundaries of order n. This definition was explored further in 2010. The results suggested that W consists, in part, of the hyperbolic network of invariant manifolds associated to the Lyapunov orbits about the L1, L2 Lagrange points near P2. The explicit determination of the set about P2 = Jupiter, where P1 is the Sun, is described in "Computation of Weak Stability Boundaries: Sun-Jupiter Case". It turns out that a weak stability region can also be defined relative to the larger mass point, P1. A proof of the existence of the weak stability boundary about P1 was given in 2012, but a different definition is used. The chaos of the motion is analytically proven in "Geometry of Weak Stability Boundaries". The boundary is studied in "Applicability and Dynamical Characterization of the Associated Sets of the Algorithmic Weak Stability Boundary in the Lunar Sphere of Influence".
Applications
There are a number of important applications for the weak stability boundary (WSB). Since the WSB defines a region of temporary capture, it can be used, for example, to find transfer trajectories from the Earth to the Moon that arrive at the Moon within the WSB region in weak capture, which is called ballistic capture for a spacecraft. No fuel is required for capture in this case. This was numerically demonstrated in 1987. This is the first reference for ballistic capture for spacecraft and definition of the weak stability boundary. The boundary was operationally demonstrated to exist in 1991 when it was used to find a ballistic capture transfer to the Moon for Japan's Hiten spacecraft. Other missions have used the same transfer type as Hiten, including Grail, Capstone, Danuri, Hakuto-R Mission 1 and SLIM. The WSB for Mars is studied in "Earth-Mars Transfers with Ballistic Capture" and ballistic capture transfers to Mars are computed. The BepiColombo mission of ESA will achieve ballistic capture at the WSB of Mercury in 2025.
The WSB region can be used in the field of Astrophysics. It can be defined for stars within open star clusters. This is done in "Chaotic Exchange of Solid Material Between Planetary Systems: Implications for the Lithopanspermia Hypothesis" to analyze the capture of solid material that may have arrived on the Earth early in the age of the Solar System to study the validity of the lithopanspermia hypothesis.
Numerical explorations of trajectories for P starting in the WSB region about P2 show that after the particle P escapes P2 at the end of weak capture, it moves about the primary body, P1, in a near resonant orbit, in resonance with P2 about P1. This property was used to study comets that move in orbits about the Sun in orbital resonance with Jupiter, which change resonance orbits by becoming weakly captured by Jupiter. An example of such a comet is 39P/Oterma.
This property of change of resonance of orbits about P1 when P is weakly captured by the WSB of P2 has an interesting application to the field of quantum mechanics to the motion of an electron about the proton in a hydrogen atom. The transition motion of an electron about the proton between different energy states described by the Schrödinger equation is shown to be equivalent to the change of resonance of P about P1 via weak capture by P2 for a family of transitioning resonance orbits. This gives a classical model using chaotic dynamics with Newtonian gravity for the motion of an electron.
References
Further reading
Belbruno, E.; Green, J (2022). “When Leaving the Solar System: Dark Matter Makes a Difference”, Monthly Notices of the Royal Astronomical Society, V510, 5154.
Belbruno, Edward (2007) Fly Me to the Moon. Princeton University Press. ISBN 9780691128221
Adler, Robert (Nov. 30, 2000) “To the Planets on a Shoe String”, Nature, V408, No. 6812, 510-512
Osserman, J (April 2005) “Mathematics of the Heavens”, Notices of the American Mathematical Society, V52, No. 4
Ross, Shane (April 2008) Book Review of Fly me to the Moon, Notices of American Mathematical Society, Volume 55, No. 4, 478-430
Casselman, R (April 2008). “Chaos in the Weak Stability Boundary”, Cover of Notices of American Mathematical Society, p549
Mathematics of Planet Earth "Low Fuel Spacecraft Trajectories to the Moon"
Physics theorems
Algorithms | Weak stability boundary | [
"Physics",
"Mathematics"
] | 1,598 | [
"Equations of physics",
"Algorithms",
"Mathematical logic",
"Applied mathematics",
"Physics theorems"
] |
71,652,174 | https://en.wikipedia.org/wiki/Trans-European%20Drug%20Information | The Trans-European Drug Information (TEDI) project is a European database compiling information from different drug checking services located on the European continent. The non-governmental organizations feeding into the database are referred to as the TEDI network.
History
The first drug checking service in Europe opened in 1986 in Amsterdam, allowing drug users to analyze the chemical composition of illicit substances that they consume. In the following years, a number of nonprofit organizations present in various other drug scenes in several countries (including in Austria, France, Germany, the Netherlands, Portugal, Spain, and Switzerland) set up drug checking services.
In 2011, a database was created for to centralize information from these services and allow for the sharing of alerts (for example on new adulterants in illicit substances or circulation of novel psychoactive substance) and the monitoring of drug markets across borders.
Between 2008 and 2013, organizations member of the TEDI network analyzed more than 45,000 samples of recreational drugs, showing similarities and discrepancies between areas of the European continent in terms of purity, formulation, or prices.
The TEDI project
The project and the network are hosted by the Polish nonprofit TEDI Nightlife Empowerment & Well-being Network (also known as NEW net or SaferNightlife).
Network
As of 2022, the TEDI network was integrated by 20 organizations across 13 countries (Austria, Belgium, Finland, France, Germany, Italy, Luxembourg, the Netherlands, Portugal, Slovenia, Spain, Switzerland, and the United Kingdom). A team of professionals from various fields (substance use disorder prevention workers, pharmacists, chemists, etc.) across network member organizations constitutes the TEDI project's team.
Database
The aims of the Trans-European Drug Information project are to collect, monitor and analyze the evolution of the European recreational drug market trends, and to regularly report the findings. Since 2011, the database has facilitated the centralization and comparison of information collected at the local level.
The TEDI database also feeds into the early warning system of the European Union Drugs Agency (EUDA, formerly EMCDDA). EUDA and the TEDI network also collaborate on the organization of conferences and trainings.
In 2019, the mobile application TripApp was launched by a consortium or organizations, sharing in real-time alerts from the TEDI database, in addition to connecting app users with local harm reduction providers. The app received an award from the Council of Europe in 2021.
Guidelines
As part of the project, guidelines and methodological recommendations have been published, such as:
Factsheets on drug checking services,
Guidance for organizations willing to create a drug checking service,
Training on personal support and counselling in nightlife settings, etc.
See also
Drug checking
Harm reduction
Substance use disorder
Drug policy
European Monitoring Centre for Drugs and Drug Addiction
Early warning system
Reagent testing
References
External links
(Official website)
Drug checking information page of the EMCDDA
Addiction and substance abuse organizations
Addiction medicine
Drug culture
Drug policy organizations
Drug safety
Early warning systems
Harm reduction
Organizations established in 2011
Public health organizations
Substance intoxication
Substance abuse | Trans-European Drug Information | [
"Chemistry",
"Technology"
] | 623 | [
"Warning systems",
"Drug safety",
"Early warning systems"
] |
71,652,539 | https://en.wikipedia.org/wiki/Endemixit | Endemixit is a project that studies the effects of reduced population size in five Italian endemic species at risk of extinction. The final objective is to estimate the risk of extinction from genomic data and contribute to the preservation of these species. The project was funded by the MUR (Italian Ministry for Research) and coordinated by the Department of Life Sciences and Biotechnology of the University of Ferrara with the involvement of five other Italian universities: Ancona, Florence, Padua, Rome Tor Vergata and Trieste.
Species under study
The species considered are all classified in danger or in critical danger of extinction in the IUCN Red List:
Podarcis raffonei (Aeolian wall lizard), a lizard with a current range restricted to three Aeolian Islands and subdivided into isolated and relatively distant populations.
Hipparchia sbordonii (Ponza grayling), currently only found on some Pontine Islands.
Acipenser naccarii (Adriatic sturgeon), once widespread in the Northern Adriatic Sea and in many rivers of Northern Italy, but today almost extinct in nature.
Bombina pachypus (Apennine yellow-bellied toad), an endemic and endangered species of the Italian Peninsula closely related to the most common European yellow-bellied toad (B. variegata).
Ursus arctos marsicanus (Marsican, or Apennine, brown bear), a subspecies of brown bear (U. arctos), present exclusively in a small region of the central Apennines Mountains.
Applications and innovative aspects
Endemixit is a genomic project applied to the conservation of biodiversity. Five reference genomes will be produced (one for each endemic species/subspecies), and 20 to 30 individuals per species will be re-sequenced (whole genomes at intermediate coverage). Population genomics analyses will be used to reconstruct past demographic processes and to estimate the genetic load possibly accumulated due to genetic drift. The results will be theoretically important to understand the genetic load dynamic. Practically, they will provide guidelines and priorities for the conservation of these endemics.
Endemixit is a partner of the European Reference Genome Atlas (ERGA), a pan-European consortium that aims to produce reference genomes of high quality for all European biodiversity to contribute to the protection of the same. Endemixit is also affiliated to the Earth Biogenome Project (EBP), an international project that aims to sequence the complete genome of all eukaryotic living beings in 10 years.
References
Bioinformatics
Conservation biology
Genetics | Endemixit | [
"Engineering",
"Biology"
] | 525 | [
"Bioinformatics",
"Biological engineering",
"Conservation biology",
"Genetics"
] |
71,652,983 | https://en.wikipedia.org/wiki/Cobalt%20oleate | Cobalt oleate is an organometallic compound with the formula Co(C18H33O2)2. When cobalt oleate is added to non-polar solvents, the viscosity rapidly increases, and then continues increasing over time. This unusual viscosity effect is caused by the formation of a weak coordination complex with the solvent molecules.
Preparation
Cobalt oleate can be synthesized by heating a solution of sodium oleate and cobalt(II) chloride to 70 °C.
2NaC18H33O2 + CoCl2 -> 2NaCl + Co(C18H33O2)2
See also
Oleic acid
References
Cobalt(II) compounds
Organocobalt compounds | Cobalt oleate | [
"Chemistry"
] | 142 | [
"Organic chemistry stubs"
] |
71,655,029 | https://en.wikipedia.org/wiki/Xx%20messenger | xx messenger is a cross-platform decentralized encrypted instant messaging service developed by PrivaTegrity Corporation and running on a blockchain called xx network. Messages are delivered over a variety of mix network first described in 2016. Users can send one-to-one and group messages, which can include voice notes and images.
xx messenger uses usernames as identifiers which can be optionally attached to standard cellular telephone numbers or email addresses for contact discovery. All communications between users are secured with quantum-resistant end-to-end encryption.
xx messenger's software is free and open-source. Its mobile clients are published under the 2-clause BSD License, while its server software is published under a modified, patent-protected Business Source License.
History
An alpha version of xx messenger was first presented on January 6, 2016 by David Chaum at the Real World Crypto conference with the stated goal of demonstrating a new type of mix network encryption scheme. The encryption scheme, known as PrivaTegrity, was described by Chaum and team of academic partners at Purdue University, Radboud University Nijmegen, University of Birmingham, and other schools.
xx messenger was released to the public as a mobile app on Android and IOS on 25 January 2022.
Architecture
cMix
xx messenger uses cMix - a network of decentralized servers called xx network that are run by independent operators in approximately 80 countries - for data transmission. cMix attempts to address traditional latency and scalability limitations of mix networks by performing computationally expensive public-key operations between mix nodes prior to any client data being transmitted over the network. Messages sent by users of xx messenger are grouped in batches of 1,000 and routed through a subset of cMix nodes. Once the mixing process is complete, each message can be retrieved and decrypted by their recipient.
Encryption protocols
The cMix protocol uses XChaCha20, BLAKE2b, HMAC-SHA-256, Diffie–Hellman key exchange, and Supersingular isogeny key exchange as cryptographic primitives. Messages are encrypted in two layers. The inner layer is encrypted with ChaCha20 symmetric encryption. This payload is then encrypted once more for transmission over the mixnet using multi-party ElGamal encryption. The encryption protocols, in addition to the properties provided by the mixnet, allow both anonymity preservation and traditional end-to-end security guarantees, as well as preliminary post-quantum security with a traditional fallback mechanism.
See also
Comparison of cross-platform instant messaging clients
Internet privacy
Secure communication
References
External links
Cross-platform software
Cryptographic software
Free and open-source Android software
Free instant messaging clients
Free security software
Free VoIP software
Internet privacy software
IOS software
Secure communication | Xx messenger | [
"Mathematics"
] | 570 | [
"Cryptographic software",
"Mathematical software"
] |
71,655,197 | https://en.wikipedia.org/wiki/Hiroko%20Nagahara | Hiroko Nagahara (, born 1952) is a Japanese cosmochemist and astromineralogist whose research studies the chemical composition and formation of chondrules, the molten mineral droplets that accrete to form asteroids and meteoroids. She is a fellow of the Earth–Life Science Institute of the Tokyo Institute of Technology, a professor emerita of Tokyo University, and a former president of the Meteoritical Society.
Education and career
Nagahara was born in 1952 in Tokyo, and studied in the faculty of science and engineering at Waseda University, graduating in 1970, earning a master's degree in 1976. She completing a doctorate in 1983 through the University of Tokyo, supervised by Ikuo Kushiro.
She joined the University of Tokyo as an assistant professor in 1984, and became a full professor there in 2001.
Recognition
Nagahara was the 2001 winner of the Saruhashi Prize. She was the 2015 winner of the J. Lawrence Smith Medal of the National Academy of Sciences "for her work on the kinetics of evaporation and condensation processes in the early Solar System and her fundamental contributions to one of the most enduring mysteries in meteoritics, the formation of the chondrules that constitute the characteristic component of the most abundant group of meteorites." In 2016 the Meteoritical Society gave Nagahara the Leonard Medal, its highest award.
In 2018, Nagahara was named as a Fellow of the Japan Geoscience Union (JpGU), "for pioneering and innovative contributions to cosmochemistry, meteoritics, and planetary science, and also for outstanding contributions to the Earth and planetary science community".
Asteroid 6225 Hiroko, discovered in 1981, was named for her.
References
1952 births
Living people
Mineralogists
Women mineralogists
Planetary scientists
Women planetary scientists
Japanese geochemists
Meteorite researchers
Waseda University alumni
University of Tokyo alumni
Academic staff of the University of Tokyo | Hiroko Nagahara | [
"Chemistry"
] | 391 | [
"Geochemists",
"Japanese geochemists"
] |
71,656,162 | https://en.wikipedia.org/wiki/Optical%20material | Optical materials are transparent materials from which optical lenses, prisms, windows, waveguides, and second-surface mirrors can be made. They are required in most optical instruments.
Most optical materials are rigid solids, but flexible and elastic materials are used for special functions. Contained liquids can also be used as optical materials.
Known optical materials include amorphous materials and crystalline materials:
Glass
Plastics
Polycarbonate
Poly(methyl methacrylate)
Sodium chloride
Strontium fluoride
Synthetic diamond
Zinc sulfide
Optical materials useful with infrared light include:
Silicon (1.2–7 μm)
Zinc selenide
Non-linear optical materials or nonlinear media transform light in various ways in nonlinear optics.
Non-linear optical materials include:
Barium borate
Some materials (optical and non-optical) can be made into first-surface mirrors, by silvering them or plating them with metal. Some metals can be highly polished, providing both support and the reflective surface of first-surface mirrors.
See also
Optical coating
References
Material
Materials | Optical material | [
"Physics",
"Chemistry"
] | 211 | [
"Applied and interdisciplinary physics",
"Optics",
"Materials",
" molecular",
"Atomic",
"Matter",
" and optical physics"
] |
71,657,761 | https://en.wikipedia.org/wiki/BIOTECanada | BIOTECanada, previously the Industrial Biotechnology Association of Canada, is a Canadian biotechnology industry association based in Ottawa, Ontario. It is an industry-funded membership organization composed of over 250 national and international pharmaceutical and gene therapy companies, medical device manufacturers, agricultural science businesses, law firms, academic institutions, research and development networks, advertising agencies, insurance companies and financial services firms.
BIOTECanada and the University of Western Ontario jointly administer the Gold Leaf Awards, presented annually to individuals and organizations who are deemed to have made significant contributions to Canada's biotechnology sector.
History
The organization was incorporated in 1987 as the Industrial Biotechnology Association of Canada.
Health Canada partnered with BIOTECanada in May 2012 to organize a summit on clinical and regulatory topics associated with biosimilars. The event was held in association with the International Alliance for Biological Standardization, and was observed by representatives from the Patented Medicine Prices Review Board and the Canadian Agency for Drugs and Technologies in Health. Panelists included representatives from academia, regulatory bodies and industry, such as UMass Memorial Health, Janssen Pharmaceuticals, the Robarts Research Institute, Alberta Blue Cross, Mount Sinai Hospital and Sunnybrook Health Sciences Centre.
In 2017, BIOTECanada published a report detailing proposed initiatives to use biotechnology to address issues including population growth, climate change, food security, health, and economic instability. President and CEO Andrew Casey sent a letter in July 2017 to Innovation, Science and Economic Development Canada proposing measures to offset costs of patent filings, and to reduce taxation on intellectual property revenues.
COVID-19
Several representatives of BIOTECanada participated as members and advisors in the COVID-19 Therapeutics Task Force convened by Innovation, Science and Economic Development Canada.
In June 2022, BIOTECanada hosted the Canada Pavilion at the BIO International Convention, an annual biotechnology conference led by the Biotechnology Innovation Organization (BIO).
Organization
Partners
BIOTECanada is partnered with Avantor, Borden Ladner Gervais, Silicon Valley Bank, and Wilson Sonsini Goodrich & Rosati. The organization is a supporting member of BioTalent Canada, a professional network for the biotechnology community. It is also a member of the Biotechnology Innovation Organization (BIO), and a founding institution of Clinical Trials Ontario. It is a participating organization of the Virtual Biosecurity Center, an initiative of the Federation of American Scientists.
Members
BIOTECanada's current membership includes:
Former members include the Agricultural Institute of Canada, BioAlberta, Centre for the Commercialization of Antibodies and Biologics, Ernst & Young, Genzyme, Innovation PEI, International Centre for Infectious Disease, Johnson & Johnson, KPMG, Life Sciences Association of Manitoba, McKesson Corporation, National Research Council Canada, Pan-Provincial Vaccine Enterprise, PricewaterhouseCoopers, Sanofi Pasteur, Shoppers Drug Mart Specialty Health Network, University of Guelph, University of Manitoba and University of Waterloo.
References
Biotechnology organizations
Scientific organizations based in Canada
Lobbying organizations in Canada | BIOTECanada | [
"Engineering",
"Biology"
] | 609 | [
"Biotechnology organizations"
] |
71,657,788 | https://en.wikipedia.org/wiki/Malaria%20therapy | The malaria therapy (or malaria inoculation, and sometimes malariotherapy) is an archaic medical procedure of treating diseases using artificial injection of malaria parasites. It is a type of pyrotherapy (or pyretotherapy) by which high fever is induced to stop or eliminate symptoms of certain diseases. In malaria therapy, malarial parasites (Plasmodium) are specifically used to cause fever, and an elevated body temperature reduces the symptoms of or cure the diseases. As the primary disease is treated, the malaria is then cured using antimalarial drugs. The method was developed by Austrian physician Julius Wagner-Jauregg in 1917 for the treatment of neurosyphilis for which he received the 1927 Nobel Prize in Physiology or Medicine.
Background
The beneficial effects of infections in mental problems were known in the Ancient world. Hippocrates in the 4th century BCE recorded bacterial infections such as dysentery and dropsy reducing the symptoms of madness; and that malaria (quartan fever) could stop epileptic convulsions. Galen in the 2nd century CE described a case of mental illness that ended after malarial infection. There are medical records from the 19th century which indicate that insanity stopped temporarily or permanently when the individuals had severe infections.
Russian psychiatrist was the first to experimentally use infections for the treatment of psychosis. In 1876, he induced fever in psychotic individuals using malaria, typhoid, and relapsing fever. He claimed that he cured 50% of all those he treated. However, his work was not widely known as his publication in 1877 was in a small journal in Odesa, Ukraine, and written in Russian. He also preferred not to spread his findings. He understood that it was a dangerous experiment and potentially controversial. It was, however, reported by J. Motschukoffsky in a German medical journal Centralblatt für die Medicinischen Wissenschaften, but the underlying cause of how malaria cured psychosis was not understood, and Rosenblum's experiment remained unknown for several decades. Rosenblum never repeated the study or tried to develop specific method for the medical treatment. The importance of the study was realised only in 1938 when Austrian physician Julius Wagner-Jauregg discussed the research at the International Neurological Congress in London.
In 1943, Samuel J. Zakon at the Northwestern University Medical School in Chicago, US, acquired the original paper of Rosenblum and published an English translation with commentary in the Journal of the American Medical Association. The commentary concluded:Rosenblium [alternative spelling] was certainly the first to appreciate the curative effect of fever itself on the psychoses. He understood and reported on the value of malaria and typhoid in the treatment of mental disease. He was the first to inoculate psychotic patients with a febrile disease. Rosenblium, though practically forgotten for over half a century, must be acknowledged as the true pioneer in this field.
Rediscovery and clinical application
Although the priority of using malaria therapy in brain disorders is generally attributed to Rosenblum, the credit of developing malaria therapy as a standard medical practice and explaining the underlying scientific principle is to Austrian physician Julius Wagner-Jauregg. Wagner-Jauregg, working at the First Psychiatry Clinic at the Asylum of Lower Austria, investigated cases of brain disorders since 1883, publishing his first paper on psychosis in 1887 titled "Über die Einwirkung fieberhafter Erkrankungen auf Psychosen" ("The Effect of Feverish Disease on Psychoses"). He soon realised that a severe type of psychosis was related to neurosyphilis, an infection of the central nervous system with syphilis (caused by a bacterium identified in 1905 as Spirochaeta pallida, later renamed Treponema pallidum). Syphilis was at the time a deadly disease characterised by delusions, paralysis, and dementia; and known as "The Great Pox" and the "disease of the century." Neurosyphilis was prevalent in Europe during the 19th century, leading to an increased asylum population during this period.
Wagner-Jauregg came to the conclusion that fever could cure psychosis after reviewing his own experiments and the historical accounts based on three phenomena: (a) the appearance of fever coincided with the disappearance of the symptoms of psychosis in medical history; (b) his findings that fever was the only possible cause for the cure of psychosis; and (c) although all psychotic individuals were not cured, the number of cures increased whenever malaria spread. He made three postulates:
The agent of treatment, febrile disease, while curing mental disorder, can still induce disease in healthy people.
Febrile disease strengthens (makes healthier) individuals with mental disorder.
Elevation of body temperature due to febrile disease is key to suppressing psychotic symptoms.
References
History of medicine
Neuroscience
Medical procedures
Physical therapy
Malaria | Malaria therapy | [
"Biology"
] | 1,010 | [
"Neuroscience"
] |
65,842,439 | https://en.wikipedia.org/wiki/Castle%20Rock%20%28Utah%29 | Castle Rock is a 4,321-foot (1,317 meter) elevation sandstone summit located in Glen Canyon National Recreation Area, in Kane County of southern Utah. It is situated north of the town of Page, and northeast of the Wahweap marina. Castle Rock towers over 600 feet above Lake Powell, and becomes an island when the lake is full. This iconic landmark of the Lake Powell area is composed primarily of Entrada Sandstone. This sandstone, which was originally deposited as sandy mud on a tidal flat, is believed to have formed about 160 million years ago during the Jurassic period as a giant sand sea, the largest in Earth's history.
Climate
According to the Köppen climate classification system, Castle Rock is located in an arid climate zone with hot, very dry summers, and chilly winters with very little snow. Spring and fall are the most favorable seasons to visit.
These data are for the Wahweap climate station on Lake Powell, two miles southwest of Castle Rock.
Gallery
See also
Colorado Plateau
List of rock formations in the United States
References
External links
National Weather Service forecast: Castle Rock
Colorado Plateau
Landforms of Kane County, Utah
Glen Canyon National Recreation Area
Lake Powell
One-thousanders of the United States
Sandstone formations of the United States | Castle Rock (Utah) | [
"Engineering"
] | 252 | [
"Colorado River Storage Project",
"Lake Powell"
] |
65,843,268 | https://en.wikipedia.org/wiki/SHIFT%20%28company%29 | SHIFT is a German smartphone and phablet manufacturer with its headquarters with design and development department in Wabern in Northern Hesse Germany and Production in China. The company focuses on fairness in manufacturing and sustainability through a modular design.
Products
Its smartphone products are called shiftphones.
Following the same principles as the phones, a modular 13.3" tablet is also in the works, scheduled for release in 2022. It uses a Tiger Lake i5-processor, features a swappable battery and two M.2 slots, and will support Windows 10 and Linux.
History
SHIFT has been developing smartphones since 2014. In the beginning Carsten and his brother Samuel Waldeck realized the project SHIFT7 through German crowdfunding platform . The brothers founded Shift GmbH, a company with limited liability regulated under German law. Further Shiftphones were launched with model series SHIFT4 and SHIFT5 in 2015.
The foundation of Shift was preceded by the crowdfunding of the smartphone shift7. The financing period was from April to July 2014 and was expected to raise €77,700, which was exceeded by one third and was therefore successful.
The company was officially founded in November of the same year and entered into the commercial register at the Amtsgericht Fritzlar.
In 2016 Shift became the first telecommunications equipment manufacturer to introduce a device deposit for all Shift products. In order to avoid waste, end users are to return defective devices to the company to ensure that they are disposed of properly or reused by second or third parties.
In June 2018, the company employs eleven people at its headquarters in Wabern and ten in Hangzhou, earning four times as much as the industry average in China.
By June 2019 Shift had sold 30,000 units.
The project grew into a small company with 15 employees in Germany, which collaborated with the Chinese production coordinator company "Vstar and Weihuaxin" in Shenzhen. Since 2018 the company has employed 10 workers in their own manufacturing facility in Hangzhou.
Critiques
Doubts in the c't
Initially, doubts were expressed about the credibility of SHIFT GmbH's corporate goals, which were formulated as fair. The computer magazine c't, for example, raised doubts about the fairness of the companies smartphone Shift5.1 in its 9/2016 issue. The article points out that the founder Carsten Waldeck did not provide any documents to support his statements. Also, statements of the Fair Production Manifesto on the manufacturer's website are remarkably vague. Furthermore, the manifesto was written by Waldeck and "signed by 'Aaron, the founder and CEO of Vstar and Weihuaxin', a company based in Shenzen, China". The company, which according to c't von Waldeck is referred to as the "main partner", in turn has the shiftphones manufactured by another company. According to c't, the manifesto is thus merely "a declaration of intent by the shift-maker, not an investigation report by an at least halfway independent third party. The conclusion of the article is correspondingly harsh on Shift5.1: it should not be considered a fairphone alternative, but merely a typical cheap smartphone.
Mixed representation at Utopia
The german ecology online portal Utopia.de also described the efforts towards more sustainable production as "intransparent". Nevertheless, Shift5 was then included in a top list of ecological smartphones.
Further representations
In contrast, the magazine Digitale Welt writes that the company attaches just as much importance to environmentally friendly measures as it does to fair working conditions and reparability. The latter is achieved through the concept of modular construction of the devices, whose individual parts can be ordered by the user and repaired with commercially available tools and tutorials.
Reports after 2017
More recent reports paint a clearer picture. Articles in other magazines have also been able to capture Carsten Waldeck's statements and prove their credibility accordingly. In June 2018, for example, golem.de of Computec Media reported in detail about the company and its efforts in the areas of sustainability and fairness. ProSieben magazine Galileo also tested - also in June 2018 - the newly published Shift6m and used video recordings to illuminate the production conditions of the in-house Shift factory on site in China. In September 2018, N-tv described the initial efforts towards fairness and sustainability as well as the history of the Shift phone's development. The computer magazine c't found more positive words about the German smartphone manufacturer in issue 15/2018, although the reporting in the context of other European providers is very brief. The ecology portal Utopia.de also no longer mentions intransparency in an article from August 2018. On December 7, 2018, Deutsche Welle headlines: "Smartphone and sustainability - is that possible? With the shiftphone it is!".
References
External links
Fair trade brands
Smartphones
Mobile phone manufacturers
Modular smartphones
Electronics companies of Germany
Privately held companies of Germany | SHIFT (company) | [
"Engineering"
] | 996 | [
"Modular design",
"Modular smartphones"
] |
65,843,361 | https://en.wikipedia.org/wiki/Comparison%20of%20PlayStation%20consoles |
2013–present
1994–2006
References
PlayStation (console)
Technological comparisons | Comparison of PlayStation consoles | [
"Technology"
] | 15 | [
"nan"
] |
65,843,625 | https://en.wikipedia.org/wiki/SN-2 | SN-2 is a chemical compound which acts as an "agonist" (i.e. channel opener) for the TRPML3 calcium channel, with high selectivity for TRPML3 and no significant activity at the related TRPML1 and TRPML2 channels. It has demonstrated antiviral activity in an in vitro model.
See also
MK6-83
ML2-SA1
References
Tricyclic compounds
Calcium channel openers
Nitrogen heterocycles
Oxygen heterocycles | SN-2 | [
"Chemistry"
] | 106 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
65,843,744 | https://en.wikipedia.org/wiki/ML2-SA1 | ML2-SA1 (EVP-22) is a chemical compound which acts as an "agonist" (i.e. channel opener) for the TRPML2 calcium channel, with high selectivity for TRPML2 and no significant activity at the related TRPML1 and TRPML3 channels. It has been used to demonstrate the role of TRPM2 in immune system function, both triggering release of the chemokine CCL2 from macrophages and stimulating macrophage migration and endolysosomal trafficking.
See also
MK6-83
SN-2
References
Calcium channel openers
Heterocyclic compounds with 3 rings
Nitrogen heterocycles
Chloroarenes
Isoxazoles | ML2-SA1 | [
"Chemistry"
] | 153 | [
"Pharmacology",
"Pharmacology stubs",
"Medicinal chemistry stubs"
] |
65,843,787 | https://en.wikipedia.org/wiki/Vivo%20Y3 | The Vivo Y3 was launched in May 2019 by Vivo. The Vivo Y3s phone served as an even more budget friendly variant, reducing prices by cutting out the Ultra-wide camera, and launched much later, on October 26, 2020. The pricing for the Vivo Y3 was around €190 (¥1500), and the Vivo Y3s launched with a price of €150 (¥1170).
References
Y3
Mobile phones introduced in 2019
Mobile phones with multiple rear cameras
Android (operating system) devices
Discontinued smartphones | Vivo Y3 | [
"Technology"
] | 112 | [
"Mobile technology stubs",
"Mobile phone stubs"
] |
65,844,491 | https://en.wikipedia.org/wiki/Waste%20light%20concrete | Waste light concrete (WLC) is a type of lightweight concrete where the traditional construction aggregates are replaced by a mix of shredded waste materials (thermoplastics, thermosetting plastics, glass, tires, incinerator bottom ash, solid agricultural waste etc.) and a special group of additives. Used in infrastructure and building construction.
History
Concrete products contain a different mix of cement + water + aggregates, depending on desired product quality. With the cost of aggregates and the waste awareness rising, a need to decrease aggregate usage and an alternative way to dispose solid waste arose. Extensive research and development around the early 1960s lead to the realization of the first samples of polystyrene based light concrete products, where the aggregates (rocks and sand mostly) had been largely or in 100% replaced by granulates of plastic materials, or plastic waste. The main problem of this concrete was its soft consistency.
By 1990, a group of engineers formulated (and later patented) the first industrially stable version of the polystyrene concrete by mixing in certain additives. The initially used additives were not health-friendly and cost too much for the product to be financially viable, but the product reached a 3-4 N/mm2 compressive strength, which was enough for wall insulation filling. It also proved that the process is possible.
In 2001, in an attempt to commercialize the technology they replaced the binding materials with a health-neutral polymer additive. Laboratory tests were completed on fire resistance and compressive tests. This light polystyrene concrete turned out to be structurally stable, light weight (from 100 to 300 kg/m3) and 100% fire retardant. A request from Argentine lead to the final formulation of the product, where they identified a big problem in pine tree leaf waste and they were interested if it could be used as aggregates. This led to the realisation in 2004 that it is not only polystyrene that could fulfill the purpose, but any small enough solid waste type, therefore any shredded mix of solid wastes.
The patent had been filed in 2015 and awarded in 2017/2018 that covers any possible additive that enables the replacement (fully or partially) of natural aggregates by mixed shredded solid waste granules.
The resulting waste light concrete product covers a group of about 3000 possible final products. Including polystyrene concrete, heavy plastic concrete, incinerated bottom ash concrete, desert sand concrete and many more, which at the time of writing resulted in around 400 samples with different physical qualities. In general, the compressive strength of the final products is between 3 N/mm2 to 12 N/mm2 with a weight of 100 kg/m3 to 800 kg/m3. Traditional gravel-concrete can be 40 N/mm2 strong and weigh over 2.000 kg/m3.
Technology
The special additive is produced in a factory and shipped to the site of application in 5–25 kg bags. It is mixed together with cement (100–300 kg/m3), waste materials (1.1-1.2 m3) and water (100-300 liters), plus 5 kg/m3 of the additive powder.
Potential waste materials include: ocean waste, fire retardant plastics, thermosetting plastics, computer and phone motherboards, polyfoam, nylon bags, crops, glass and rubber products, incinerated bottom ash and other energy production waste, industrial processing byproducts, packaging materials and many more. Raw materials are shredded to less than 10 mm, do not have to be selected or washed. It is possible to use desert sand or low quality aggregates as main or filling materials.
On the working site, only the traditionally used concrete processing tools are needed for mixing, pumping or casting, which means no extra costs and a very high rate of market availability. The technology replacement cost is nearly zero.
Circular economy
The produced waste light concrete can be 100% recyclable at the end of the product life cycle (or in case of force majeure) by simply shredding the concrete on-site and remixing it into a new batch of waste light concrete for an indefinite number of times.
Laboratory results showed no leeching or other environment polluting effects of the process or the product.
General usage
Not applicable for: weight bearing structural concrete, high-friction contact surface.
Waste plastic road / highway base
House base
Insulating walls
Bricks and blocks
Pre-cast walls
Comparable waste processing technologies
Plastic asphalt / plastic road
For decades (unknown), asphalt producers include about 0.5% soft plastic in the asphalt mix to increase durability of the road and to decrease at least very little the cost of building road surfaces. Probably the most well known 'plastic road' technology to date, it improves the quality of the top layer of the road. The input plastic types are very limited as they have to melt into the asphalt mix at 165 degree Celsius (thermoplastics), and the technology has a high initial investment and low expandability. As a comparison, plastic road claims to dispose 8–10 kg (or 4-6%) of selected and washed plastic waste in the road surface per tons of asphalt, while waste light concrete can dispose around 800 kg / tons of road base concrete with only low energy consumption shredding and mixing at room temperature. However, these two technologies can be combined in the same stretch of road. It is possible to build plastic blocks as road building units from soft plastics, which is a complex process, and leads to a recyclable road material that has fire hazard risks as it is made from flammable plastic.
Plastic bricks
Some thermoplastics can be melt and compressed together into solid plastic bricks. The raw materials are very limited, the machinery can be costly and the output speed is also limited by technology. It is possible to DIY hand-compress and oven-melt the bricks, which results in low cost and low output. Another method to store soft household plastic is to compress it by hand into a plastic drink bottle and stack them as building blocks as a no-cost building material.
Rubber road base
Car tire granulates are used in road base as a stabilizing layer or in small quantities as a binding agent in asphalt. The concrete volume ratio is very small.
Research
There is a large variety of research that has been and continues to be carried out to study the feasibility of waste plastic and other waste materials for usage in lightweight concrete. This only becomes more important as the demand for concrete increases, and continues to exacerbate the catastrophic effects of sand and gravel mining, along with the general carbon emissions that result from concrete production.
Plastic-infused concrete
The replacement of fine aggregates in concrete (e.g. sand) with plastic naturally will decrease the Young’s Modulus and compressive strength of the material, as plastics have lower strength than typical fine aggregates, and their hydrophobic properties decrease their adhesion to the concrete matrix at the interfacial transition zone. This makes plastics suitable for use in lightweight concrete, where compressive strength is less important.
Research has generally shown that a replacement of fine aggregates with plastic by about 10% is optimal for minimizing the strength reduction caused by adding plastic. Other benefits of adding plastic aggregates to concrete include reduction in heat conduction, reduction in density, and increase in fracture energy.
Several studies have been conducted to address the issue of plastic’s adhesion with the concrete matrix. Studies show that treating plastic aggregate with gamma radiation before adding to the concrete improves compressive strength of the material. MIT students were able to produce concrete that is up to 20% stronger than conventional concrete with this method. Similarly, microwave radiation pre-treatment of PET was shown to improve adhesion with cement paste. Research is also being done to assess the use of air reducing agents to increase adhesion.
Other waste materials
Aside from plastic, other waste materials can be useful for replacing fine aggregates in concrete, depending on the requirements for specifications such as specific gravity, specific strength, and particle size distribution. Researchers have demonstrated the viability of materials including coconut shell, glass powder, oil palm shell, waste clay brick, and various types of ash for this purpose.
References
Concrete
Waste minimisation | Waste light concrete | [
"Engineering"
] | 1,687 | [
"Structural engineering",
"Concrete"
] |
65,847,542 | https://en.wikipedia.org/wiki/Antheridiogen | Antheridiogens are a class of chemicals secreted by fern gametophytes that have "been shown to influence production of male gametangia and thus mating systems in a large number of terrestrial fern species". Antheridiogens are only observed in homosporous fern species, as all gametophytes are potentially bisexual (have the ability to produce both archegonia and antheridia).
Background
The first study regarding antheridiogen was published by Walter Döpp in 1950. In this article, he explains the discovery of a molecule, which he titled "A-substanz", that caused premature formation of antheridia when agar media was reused after cultivation of Pteridium aquilinum. A majority of the studies regarding antheridiogen were done by two researchers, Ulrich Näf and H. Schraudolf.
Sex-determination pathway
The way in which antheridiogen determines sex in ferns is a "spatiotemporally split gibberellin synthesis pathway". Gibberellin is a group of hormones that control plant processes. In the first step of this process, gametophytes, or prothalli, express gibberellin (GA) specific genes, which produces a GA intermediate molecule that is then secreted into the external environment. In the second step, antheridiogens are taken up by neighboring gametophytes in the colony and undergoes a series of molecular changes that allow it to finally induce or suppress formation of antheridia or archegonia. This helps regulate the sex ratio of the colony.
The timing with which antheridiogen affects the gender of growing gametophytes is still under study. One theory states that "the spores that germinate first develop as hermaphrodites and secrete antheridiogen, while those that germinate later or develop more slowly become male under the influence of the secreted antheridiogen". Depending on the ratio of males to hermaphrodites, either outcrossing or inbreeding is selected for by the population.
Studies performed on Ceratopteris richardii have proven that a growing gametophyte is only able to respond to its own antheridiogen for a brief period of time in very early stages of growth, and that if exposure is removed, undifferentiated cells can revert from male to hermaphrodite. The reversibility of male expression proves that levels of antheridiogen must be maintained in order to keep male expression from disappearing.
Antheridiogen has also been shown to allow spores that are grown in complete darkness to grow. Spores that are buried underground, if reached by antheridiogen, can form gametophytes that reach the surface. Or, they form a small amount of antheridia, and the sperm produced can reach the female gametophytes above ground.
The way in which the sex of each individual is determined is a form of environmental sex determination (ESD). In contrast to chromosomal sex determination, sex determination through ESD is extremely flexible, allowing for sex changes throughout the individual's life in response to colony or environmental changes. One study performed on the fern species Woodwardia radicans found that sex expression of mature gametophytes is dependent on stress conditions. In good conditions, gametophytes reached sexual maturity at a larger size and became females and then bisexuals, whereas in stressful conditions, gametophytes reached sexual maturity at a smaller size and became males.
Connections
The idea of an antheridiogen is very similar to that of pheromones, which exist in some mammals. Although mammalian sex determination is decided by chromosomes, chemicals called pheromones are released, detected by the olfactory system, and can control social behaviors and hormone levels. The presence of human pheromones remains a long-contested topic, as there have not been any studies that completely prove the existence of pheromones or of a possible pathway of detection.
References
Plant reproduction
Plant hormones
Ferns | Antheridiogen | [
"Biology"
] | 837 | [
"Behavior",
"Plant reproduction",
"Plants",
"Reproduction",
"Ferns"
] |
65,848,187 | https://en.wikipedia.org/wiki/Madagascar%20henipavirus | Madagascar henipavirus (MadV) is a poorly characterized henipavirus type. Currently it has only been detected serologically among Madagascan rousettes. High cross reactivity was observed with Hendra and Nipah henipaviruses.
References
Henipavirus | Madagascar henipavirus | [
"Biology"
] | 61 | [
"Virus stubs",
"Viruses"
] |
65,851,158 | https://en.wikipedia.org/wiki/Una%20D.%20McCann | Una D. McCann (born 1958) is a board certified psychiatrist and researcher at Johns Hopkins School of Medicine in the Department of Psychiatry. She is also the Director of the Anxiety Disorders Program, and Co-Director of the Center for Interdisciplinary Sleep Medicine and Research, and Associate Program Director at the Johns Hopkins Bayview Medical Center. McCann is considered to be an expert in anxiety and stress disorders and her primary areas research revolves around amphetamine-induced monoamine neurotoxicity and neurobiology of anxiety disorders.
Education
McCann graduated from Princeton University in 1980 with a Bachelors of Science while on a four year academic scholarship. After graduating, McCann went on to attended Duke University school of Medicine in 1984 and completed residency at Stanford University School of Medicine and Walter Reed Army Medical Center in 1988. In 1985, she became board certified in California and in 1990 in Maryland.
Career
Prior to working at Johns Hopkins School of Medicine, McCann was a psychiatrist at Walter Reed Army Medical Center and was Chief of the Unit on Anxiety at the National Institute of Mental Health at the NIH. Currently she is a practicing physician, professor of Neurology and Psychiatry, and holds many executive roles within Johns Hopkins School of Medicine and at Johns Hopkins Bayview Medical Center. She is an editorial board member of the Journal of Women’s Health and Gender Based Medicine, Women in Medicine, Adicciones, Journal of Addiction, Journal of Sleep Disorders: Treatment and Care, WebmedCentral Plus, and Psychotherapy and Psychological Disorders and also holds a membership with the Society for Neuroscience, since 1988.
MDMA research
McCann has written many research articles studying the effects of MDMA, including adverse reactions of MDMA and how it leads to serotonin neuron damage. She and her husband, fellow Johns Hopkins Professor and Physician George A. Ricaurte, have also linked abnormalities such as altered sleep, neuroendocrine function, altered behavior to 5-HT receptor drugs, and increased impulsiveness with MDMA users. In addition, she has also done research on neurotoxicity MDMA using functional magnetic resonance imaging comparing the neurocognitive capabilities of MDMA users and nonusers, as studies on animals using MDMA have shown negative effects. McCann and her husband Ricaurte have had one study published in the journal Science subject to retraction. In 2002, Ricaurte's primate study of MDMA usage and brain damage did not use ecstasy and that ten squirrel monkeys and baboons were injected with overdoses of methamphetamine, instead of MDMA, resulting in two animals dying and the withdrawal of four other academic papers. Ricaurte, McCann, and other scientist involved wrote a response to the retraction addressing the errors made in their research.
Anxiety and stress research
McCann has been involved in a broad array of stress and anxiety research revolving around PTSD, depression, and traumatic brain injury. In regards to depression, McCann has worked on studying on the neuroanatomical markers of depression after traumatic brain injury through the use of diffusion tensor imaging (DTI) which measures the translational motion of water molecules and on individuals with depression after suffering from myocardial infarction. She has investigated assessing depression symptoms among patients hospitalized with acute myocardial infarction, coming to the conclusion that depression screening should be utilized in order to prevent depression among patients. She has also been involved with associating a link between heart hart and posttraumatic stress disorders with severe burn patients. McCann has investigated the association between mild traumatic brain injury and sleep disturbances through the use of sleep polysomnograms (PSG) and sleep EEG power spectra (PS), which could become a possible diagnostic marker for brain injury.
Psilocybin research
McCann has been a part of psilocybin research, a naturally occurring psychedelic drug, in partnership with other Johns Hopkins scientist, including working with Roland Griffiths, who was featured on 60 Minutes regarding the studies done. The psilocybin research has focused on the mystical experiences associated with individuals taking psilocybin for religious purpose and observing the psychological effects. McCann has also contributed to studies regarding psilocybin's use among cancer patients and healthy volunteers in two separate studies, investigating whether the use of this psychedelic increased psychological coping and decreased depression due to spirituality being associated with the two.
Awards
McCann has published more than 140 peer-reviewed manuscripts and over 9,000 citations.
Her awards include:
(1980) Phi Beta Kappa society;
(1980) Sigma Xi Society and Sigma Xi award in Psychology;
(1980) Howard Hughes Foundation Student Scholar;
(1995) U.S. Army Commissioned Officers Award.
References
Princeton University alumni
Duke University School of Medicine alumni
Sleep researchers
Johns Hopkins University faculty
1958 births
American physicians
Walter Reed Army Medical Center
American psychiatrists
Living people | Una D. McCann | [
"Biology"
] | 980 | [
"Sleep researchers",
"Behavior",
"Sleep"
] |
65,853,439 | https://en.wikipedia.org/wiki/Piezospectroscopy | Piezospectroscopy (also known as photoluminescence piezospectroscopy) is an analytical technique that reveals internal stresses in alumina-containing materials, particularly thermal barrier coatings (TBCs). A typical procedure involves illuminating the sample with laser light of a known wavelength, causing the material to release its own radiation in response (see fluorescence). By measuring the emitted radiation and comparing the location of the peaks to a stress-free sample, stresses in the material can be revealed without any destructive interaction.
Piezospectroscopy can be used on any material that exhibits fluorescence, but is almost exclusively used on samples containing alumina because of the presence of chromium ions, either as part of the composition or as an impurity, that greatly increase the fluorescent response. As opposed to other methods of stress measurement, such as powder diffraction or the use of a strain gauge, piezospectroscopy can measure internal stresses at higher resolution, on the order of 1 μm, and can measure very quickly, with most systems taking less than one second to acquire data.
Theory
Piezospectroscopy takes advantage of both the microstructure and composition of TBCs to generate accurate results.
A typical candidate for piezospectroscopy contains three layers:
Ceramic topcoat – A thick, highly porous layer, usually composed of yttria-stabilized zirconia (YSZ), which displays low thermal conductivity and stability at high operating temperatures
Thermally grown oxide (TGO) – A thin layer that results from oxidation of the bond coat. Because oxidation is inevitable at high temperatures, the goal of an effective TBC is slow and uniform growth of an oxide.
Metallic bond coat – A metallic layer directly above the substrate intended to prevent corrosion and oxidation
Coating failure is usually a result of spalling or cracking of the TGO layer. Because the TGO is buried beneath a thick layer of ceramic, subsurface stresses are generally difficult to detect. The use of an argon-ion laser makes this possible. The optical band gap (threshold for photon absorption) of the ceramic topcoat is much greater than the energy of argon laser light, effectively making the topcoat translucent and allowing for interaction with the TGO layer. Within the TGO, it is the chromium (Cr3+) ions that produce strong emission spectra and allow for piezospectroscopic analysis.
At the subatomic level, the laser light of known wavelength (usually 5149Å) causes the outer electron in the Cr3+ ions to absorb the incoming radiation, which raises it to a higher energy level. Upon returning to a lower energy state, the electron releases its own radiation. Because the energy levels are discrete, the spectrum for stress-free aluminum oxide always exhibits two peaks at wavelengths 14,402 cm−1 and 14,432 cm−1. The wavelength and frequency are related through:
where v is the frequency, λ is the wavelength, and c is the speed of light. If the coating is under a compressive stress, the peaks will be shifted downward while a tensile stress will shift them upward.
The frequency shift is given by the equation:
where is the piezospectroscopic tensor and is the residual stress within the coating.
Instrumentation
In order to obtain accurate results, a few finely tuned instruments must work in tandem:
Laser
A light source, such as a laser, is instrumental to piezospectroscopy. Narrow bandwidth lasers are preferred due to the increased resolution of the resulting spectrum. The fluorescent response is stronger at lower frequencies, but excessively low frequency light can cause sample degradation and interference with the ceramic surface of the coating.
Microscope
A microscope is generally used to isolate a certain section of a sample. Because TBC failure can begin at microscopic scales, magnification is often essential to accurately detect stresses.
Monochromator
A monochromator is used to filter out weakly scattered light and permit the strong emission peaks from the fluorescent response. In addition, notch or long-pass optical filters are used to filter the peak from the laser wavelength itself.
Detector
Many types of detectors are used with piezospectroscopy, the two most common being dispersion through a spectrograph or an interferometer. The resulting signal can be analyzed through Fourier Transform (FT) methods. Array detectors such as CCDs are also common, with many different types being suited for different ranges of wavelengths.
Procedure
The laser beam is directed through a lens and focused on the sample
The reflected beam is sent through a set of filters, which remove signal noise and isolate the desired range of the signal
The filtered beam is once again focused through a lens and split into several beams with a diffraction grading
The diffracted signal is reflected onto a detector, which converts the optical information into digital samples that are sent to a computer for further analysis
Applications
Piezospectroscopy is used in industry to ensure safe operation of TBCs.
Quality control
It is critical that TBCs be applied properly in order to prevent premature microfractures, delamination, and other structural failure. Through piezospectroscopy, parts can be put into service with the assurance of a properly protected substrate.
Nondestructive inspection/remaining lifetime assessment
Piezospectroscopy can accurately describe the extent of any discovered damage and provide accurate lifetime estimates in actual use. In addition, piezospectroscopy can be set up in situ. This, along with its noninvasive nature, makes piezospectroscopy an efficient method of onsite damage assessment.
References
Materials science | Piezospectroscopy | [
"Physics",
"Materials_science",
"Engineering"
] | 1,167 | [
"Applied and interdisciplinary physics",
"Materials science",
"nan"
] |
65,853,962 | https://en.wikipedia.org/wiki/Hoffmann%20Institute%20of%20Advanced%20Materials | The Hoffmann Institute of Advanced Materials (HIAM) is a science research institute affiliated to Shenzhen Polytechnic in Shenzhen, China. As the eighth institute at Shenzhen named after a Nobel laureate, it was founded in February 2018 under the tutelage of the theoretical chemist Roald Hoffmann. The institute was officially opened with a formal ceremony in May 2019.
Its research topics cover novel functional materials, with an emphasis on their properties and applications in new energy and renewable energy fields. The institute's key research areas are photo-electric materials, energy-storage materials, and energy-efficient materials. The institute consists of three departments: a computational laboratory, a materials research laboratory, and a device commercialization laboratory.
The institute holds strong ties with other international laboratories dealing with energy-related research, including those from Kyoto and Osaka (Japan), Aachen and Düsseldorf (Germany), NIST (U.S.), and Skoltech (Russia). Likewise, the institute collaborates in regard to the chemistry, physics, and materials science of complex mixed-anion inorganic compounds with universities and research institutions in Kyoto (Japan), Oxford (UK), Antwerp (Belgium), and Bordeaux (France).
Advisory board
The institute is supported by a high-level advisory board, which currently includes Lin Jianhua, Francis J. DiSalvo, Galen Stucky, Maochun Hong, Xiaoming Chen, Robert Cava, and Markus Antonietti.
Research accomplishments
Recent characteristic research with the institute as first affiliation has been dealing with the encapsulation of multiple dyes into nanocrystalline metal-organic frameworks for energy-efficient lighting devices, the clarification of the real-time formation mechanism of quantum wells for stable and efficient perovskite photovoltaics, the encapsulation of a porous organic cage into the pores of a metal-organic framework for enhanced CO2 separation, the design of metal-organic frameworks for alkane separation and adsorption of noble gases such as xenon, the synthesis of a chemically stable cucurbit[6]uril-based hydrogen-bonded organic framework for SO2/CO2 separation, the first-principles prediction of nitrogen-based transition-metal guanidinates TCN3 and ortho-nitrido carbonates T2CN4 for photoelectrochemistry, the mechanochemical one-pot fabrication of a
monolithic cucurbituril−encapsulating metal−organic framework from a flowing gel, and the prediction of BeCN2 as the lightest representative of II–IV–V2 compounds.
By the end of 2021, the institute had published several key papers in outstanding international journals such as the Journal of the American Chemical Society. Based on this achievement, the Shenzhen Polytechnic already made it into the top 200 Chinese institutions within Nature's publication index.
References
External links
Materials science institutes
Research institutes in China | Hoffmann Institute of Advanced Materials | [
"Materials_science"
] | 608 | [
"Materials science organizations",
"Materials science institutes"
] |
54,464,966 | https://en.wikipedia.org/wiki/Bedding%20ceremony | The bedding ceremony refers to the wedding custom of putting the newlywed couple together in the marital bed in front of numerous witnesses, usually family, friends, and neighbors, thereby completing the marriage.
The purpose of the ritual was to establish the consummation of the marriage, either by actually witnessing the couple's first sexual intercourse, or far more often symbolically, by leaving before consummation. It symbolized the community's involvement in the marriage. The legally binding nature of the ceremony varied greatly from place to place and through time.
Traditions
Bedding rituals have been practised in various European cultures, the ceremony differing from place to place. The people putting the newlyweds in bed have usually included their family, friends and wider community. The ritual is often associated with music, bawdy songs and jokes. It symbolised the community's involvement in the marriage and especially in the couple's sexual intimacy, but also their marital fidelity. The consummation itself, i.e. the couple's first sexual intercourse, was not witnessed in most of Western Europe.
In England, the ceremony usually began with a priest blessing the bed, after which the newlyweds prepared themselves for bed and drank sweet and spicy wine. The groomsmen and the bridesmaids then sat on the sides of the bed and threw the couple's stockings at them; a hit was believed to indicate that the thrower would soon marry. Finally the curtains were drawn around the bed and the couple was left alone. Some newlyweds refused to take part in the bedding ceremony. King Charles I of England () notably barred the door of his bedroom; however, despite his rejection, the custom remained prevalent for another century among all social classes, including the royal family.
In the 16th century, in what is now Germany, the bedding ceremony was performed to the sound of pipes, drums and "obscene noises", after which the couple was left alone and the guests continued celebrating loudly enough for the newlyweds not to be heard. In many places, the newlyweds were dressed for bed separately by their family or community and then led to the bedroom. In others, the couple was expected to rejoin the party afterwards. During the Reformation era, the bedding ceremony was associated with rituals that assigned socioeconomic rights and duties to the bride as housewife.
In Scandinavia, it was the most distinguished wedding guest who led the bride to bed in a festive procession. After putting them in bed, the guests offered dishes to the newlyweds and quickly ate with them before leaving them alone. Due to the ritual's importance, specially decorated wedding beds were sometimes borrowed from friends, family or neighbours. The bedding eventually became merely symbolic, with the bride's parents covering the newlyweds with a blanket and then uncovering them.
Legal consequences
The original purpose of the bedding ceremony was to establish the consummation of the marriage, without which the union could be annulled. The legally binding nature of the ritual was unclear to many, particularly to lower classes. One marriage in Britain was annulled on the pretext that the bride had run away within 15 minutes of the ritual, and in another case, a clandestine marriage was made public when the pregnant wife shared her husband's deathbed. Public bedding in 18th-century Britain was widely believed to give additional legitimacy to the marriage. In Scotland, although marriage was formed by simple consent and required no formalities or consummation, the bedding rituals were widespread but unstructured; a couple simply wanted someone to see them in bed together. A couple could also be pressured into marriage in this way: a person stumbling upon an unmarried couple in bed could pronounce them man and wife on the spot.
In medieval Scandinavia, the bedding ceremony was of great legal importance. Laws in many Swedish provinces regarded public bedding as essential to the completion of a marriage, but the legal importance later diminished due to new royal laws. In Iceland, a marriage was only valid if it included the bedding ritual witnessed by at least six men.
In the case of royal marriages, the ceremony took on added significance.
In popular culture
The bedding ritual has featured in popular culture for centuries. It has been hinted at in The Penny Wedding, an 1818 painting by David Wilkie, and possibly also in the homonymous 1819 painting by Alexander Carse.
A bedding ceremony takes place in the film The Wedding Banquet.
Numerous songs also make references to the ceremony.
In the television series Game of Thrones, a bedding ceremony features in several episodes. It is conceived as a "Westerosi tradition following the wedding feast", wherein the attendees forcibly undress and carry the newlyweds to their bed. The intention is to "celebrate a marriage's consummation".
See also
Beilager
Consummation
Yichud
Notes
References
Bibliography
Wedding traditions
Beds
Sex and the law | Bedding ceremony | [
"Biology"
] | 1,003 | [
"Beds",
"Behavior",
"Sleep"
] |
54,466,482 | https://en.wikipedia.org/wiki/Fluorochromasia | Fluorochromasia (Greek flōr χρῶμα- Pronunciation: flu̇r·ō·krəmā·zhə), is a cellular phenomenon characterized by immediate appearance of bright green fluorescence inside viable cells upon exposure to certain membrane-permeable fluorogenic substrates such as fluorescein diacetate, fluorescein dibutyrate and fluorescein dipropionate.
The phenomenon is widely used to measure cellular viability of many different species including animals, plants, and microorganisms. Moreover, fluorochromasia has been observed within organs, embryos, and zebrafish. Fluorochromasia has many applications including histocompatibility testing, measurement of cytotoxic antibodies, in vitro chemo sensitivity testing of tumors, and fluorochrome intercellular translocation. It has been applied with plants, bacteria, mammalian oocytes, mouse embryos, and human tumor cells.
History
In 1966, Rotman and Papermaster accidentally discovered fluorochromasia while studying intracellular enzymes using fluorogenic substrates. They studied its mode of action and presented a molecular model in which intracellular retention of fluorescein depends on the integrity of the cell membrane. Non- polar molecules of fluorescein-esters, such as fluorescein diacetate, readily enter the cell and are hydrolyzed
by non-specific esterases producing fluorescein, as the polar compound. In viable cells, the intracellular fluorescein is unable to readily pass through the intact membrane (i.e., it leaks slowly), accumulating in the cytoplasm of the cell. Their model is illustrated in Figure 1.
References
Cell biology | Fluorochromasia | [
"Biology"
] | 364 | [
"Cell biology"
] |
54,468,621 | https://en.wikipedia.org/wiki/Alaxala%20Networks | , commonly known as its brand Alaxala, is a Japanese company headquartered in Kawasaki, Kanagawa, Japan, that offers networking hardware products.
Overview
In 2004, Alaxala Networks Corp. was originally established, as the merger between Hitachi and NEC networking hardware divisions. The name of Alaxala was derived from "ALL Access for eXpert and Latent Association", and more that "Ala" in Latin means "Wing", and "X" means "networking eXchange", so the company intended the two "Ala" (Hitachi and NEC) connected and collaborated by "X" tightly.
The company is basically fabless company, designing the products, mostly ordering to manufacture them to Hitachi enterprise servers division factory in Hadano, Kanagawa, Japan. The company offers networking hardware products, network router and network switch etc. Alaxala products are sold and installed mostly in Japanese domestic market and for enterprises, but we can find several products at some online shopping, Amazon.com etc.. The business type and scope is same as Allied Telesis, that is also the company in Japan. And they are collaborated for producing networking hardware sold in both brands.
Alaxala official agencies are Hitachi, NEC, Itochu Techno-Solutions, Net One Systems, and Alaxala has contributed to offer the various networking hardware products to major communication companies in Japan, such as NTT, KDDI and Softbank etc..
On August 24, 2012, Alaxala was known that Tokyo Stock Exchange (TSE) announced that TSE core system outage happened due to the software bugs on Alaxala networking hardware.
Alaxala also sponsors IT professional certifications for Alaxala products, like Cisco and Oracle etc..
See also
List of companies of Japan
List of networking hardware vendors
References
External links
Official website
Computer companies of Japan
Computer hardware companies
Companies based in Kawasaki, Kanagawa
Computer companies established in 2004
Electronics companies of Japan
Networking hardware companies
Japanese brands
Japanese companies established in 2004 | Alaxala Networks | [
"Technology"
] | 406 | [
"Computer hardware companies",
"Computers"
] |
54,469,695 | https://en.wikipedia.org/wiki/Watson%20Davis%20and%20Helen%20Miles%20Davis%20Prize | This prize should not be confused with the Watson Davis Award from the Association for Information Science and Technology.
The Watson Davis and Helen Miles Davis Prize of the History of Science Society is awarded yearly for a book published, during the past three years, on the history of science for a wide public. The book should "introduce an entire field, a chronological period, a national tradition, or the work of a noteworthy individual." The book can be written by multiple authors or editors and is required to be written in English and suitable for an audience including undergraduates and readers without specialized, technical knowledge. The author (or collective author) receives 1,000 U.S. dollars and a certificate. The prize, established in 1985, is named in honor of Watson Davis and Helen Miles Davis who were science popularizers in the USA.
Prize winners of the Watson Davis and Helen Miles Davis Prize
1986 Daniel J. Boorstin, The Discoverers: A History of Man’s Search to Know His World and Himself (New York: Random House, 1983).
1987 Thomas L. Hankins, Science in the Enlightenment (Cambridge: Cambridge University Press, 1985).
1988 John Heilbron, The Dilemmas of an Upright Man: Max Planck as Spokesman for German Science (Berkeley: University of California Press, 1986).
1989 Joan Mark, A Stranger in Her Native Land: Alice Fletcher and the American Indians (Lincoln: University of Nebraska Press, 1988). biography of Alice Fletcher.
1990 Robert W. Smith, The Space Telescope: A Study of NASA Science, Technology, and Policy (Cambridge: Cambridge University Press, 1989).
1991 Nancy G. Siraisi, Medieval and Early Modern Medicine: An Introduction to Knowledge and Practice (Chicago: University of Chicago Press, 1990).
1992 John Hedley Brooke, Science and Religion: Some Historical Perspectives (Cambridge: Cambridge University Press, 1991).
1993 James Moore and Adrian Desmond, Darwin: The Life of a Tormented Evolutionist (London: Michael Joseph, 1991).
1994 David C. Lindberg, The Beginnings of Western Science: The European Scientific Tradition in Philosophical, Religious, and Institutional Context, 600 B.C. to A.D. 1450 (Chicago: University of Chicago Press, 1992).
1995 Victor J. Katz, History of Mathematics: An Introduction (New York: Harper Collins, 1993).
1996 Betty Jo Teeter Dobbs and Margaret C. Jacob, Newton and the Culture of Newtonianism (Humanities Press, 1995).
1997 Richard Rhodes, Dark Sun: The Making of the Hydrogen Bomb (Simon & Schuster, 1995).
1998 Ruth Lewin Sime, Lise Meitner: A Life in Physics (Berkeley: University of California Press, 1996).
1999 Daniel J. Kevles, The Baltimore Case: A Trial of Politics, Science and Character (W.W. Norton & Company, 1998).
2000 Gregg Mitman, Reel Nature: America’s Romance with Wildlife on Film (Harvard University Press, 1999).
2001 Nancy Tomes, The Gospel of Germs: Men, Women, and the Microbe in American Life (Harvard University Press, 2000).
2002 Peter Dear, Revolutionizing the Sciences: European Knowledge and Its Ambitions, 1500-1700 (Princeton University Press, 2001).
2003 Ken Alder, The Measure of All Things: The Seven Year Odyssey and Hidden Error that Transformed the World (The Free Press, 2002, on Jean-Baptiste Joseph Delambre's meridian expedition in France in the 1790s)
2004 Jeff Hughes, The Manhattan Project: Big Science and the Atomic Bomb (Columbia University Press/Icon Books, 2003)
2005 Alan M. Kraut, Goldberger’s War: The Life and Work of a Public Health Crusader (Hill and Wang, 2004). biography of Joseph Goldberger.
2006 Robin Marantz Henig, Pandora’s Baby: How the First Test Tube Babies Sparked the Reproductive Revolution (Houghton Mifflin Press, 2004).
2007 Matt Ridley, Francis Crick: Discoverer of the Genetic Code (Atlas Books, Harper Collins Publishers, 2006).
2008 Helen Rozwadowski, Fathoming the Ocean: The Discovery and Exploration of the Deep Sea (Belknap Press, 2005).
2009 Charles Seife, Sun in a Bottle: The Strange History of Fusion and the Science of Wishful Thinking (Viking Adult, 2008).
2010 Marcia Bartusiak, The Day We Found the Universe (Pantheon Books, 2009).
2011 Naomi Oreskes and Erik M. Conway, Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming (Bloomsbury Press, 2010).
2012 Mark Barrow, Nature’s Ghosts: Confronting Extinction from the Age of Jefferson to the Age of Ecology (University of Chicago Press, 2009).
2013 David Kaiser, How the Hippies Saved Physics: Science, Counterculture and the Quantum Revival (W.W. Norton & Company, 2011).
2014 W. Patrick McCray, The Visioneers: How a Group of Elite Scientists Pursued Space Colonies, Nanotechnologies, and a Limitless Future (Princeton University Press, 2012).
2015 Martin Rudwick, Earth's Deep History: How It Was Discovered and Why It Matters (The University of Chicago Press, 2014).
2016 Jacob Darwin Hamblin, Arming Mother Nature: The Birth of Catastrophic Environmentalism (Oxford University Press, 2013).
2017 Tania Munz, The Dancing Bees: Karl von Frisch and the Discovery of the Honeybee Language (University Of Chicago Press, 2016).
2018 Jim Endersby, Orchid: A Cultural History (University of Chicago Press, 2016).
2019 Michael F. Robinson, The Lost White Tribe: Explorers, Scientists, and the Theory that Changed a Continent (Oxford University Press, 2016).
2020 Cathy Gere, Pain, Pleasure and the Greater Good, from the Panopticon to the Skinner Box and Beyond (University of Chicago Press, 2017).
2021 Matthew Stanley, Einstein's War: How Relativity Triumphed Amid the Vicious Nationalism of World War I (Dutton, 2019).
2022 Marga Vicedo, Intelligent Love: The Story of Clara Park, Her Autistic Daughter, and the Myth of the Refrigerator Mother (Beacon Press, 2021).
2023 Jo Marchant, The Human Cosmos: Civilization and the Stars (Penguin Random House, 2020).
References
Awards established in 1985
History of science awards
1985 establishments in the United States | Watson Davis and Helen Miles Davis Prize | [
"Technology"
] | 1,325 | [
"Science and technology awards",
"History of science awards"
] |
54,470,224 | https://en.wikipedia.org/wiki/3D%20nowcasting | 3D nowcasting refers to an experimental technology of nowcasting in meteorology that uses a rapid phased-array radar to predict precipitation several minutes in advance. The phased-array radar takes a scan of the sky in anywhere from 10 to 30 seconds, viewing 100 vertical levels in a range of 60 km. thus providing inputs every 30 seconds. It divides the sky into several "layers" and uses a new algorithm for forecasting very quickly. The models use the K computer, requiring a large amount of observational data, and a large amount of computational power. The radar produces 100 times more data than the conventional parabolic antenna radar.
Current research
Current research is being led by the RIKEN Advanced Institute for Computational Science (AICS) with the National Institute of Information and Communications Technology (NICT), Tokyo Metropolitan University, and Osaka University. The technology is in experimental form as of July 4, 2017.
Past research
Since 2003, the U.S. National Oceanic and Atmospheric Administration has been experimenting with phased-array weather radar as a replacement for conventional parabolic antenna to provide more time resolution in atmospheric sounding. This could be significant with severe thunderstorms, as their evolution can be better evaluated with more timely data.
Availability
3D nowcasting is being tested in Osaka, Kyoto and Kobe, all in Japan.
Alternatives
Parabolic-antenna radar, which scans every 5 minutes for 15 scan levels.
References
Weather prediction
Radar meteorology | 3D nowcasting | [
"Physics"
] | 290 | [
"Weather",
"Weather prediction",
"Physical phenomena"
] |
54,470,446 | https://en.wikipedia.org/wiki/Sarantaporo.gr | Sarantaporo.gr is a non-profit wireless network community founded in 2013 in Elassona Municipality in Greece. The network helps locals organize cooperative work to deploy and operate the wireless network infrastructure, organized as a commons.
The WCN participated in the CONFINE, the netCommons and the MAZI research projects. A documentary presents the networks in the Sarantaporo area.
References
Community networks
Wireless community networks
Wireless network organizations | Sarantaporo.gr | [
"Technology"
] | 90 | [
"Wireless networking",
"Wireless network organizations"
] |
54,470,471 | https://en.wikipedia.org/wiki/KOSMICA | KOSMICA is an institute that runs poetical and critical projects about outer space activities and their impact on Earth. Its central activity is a series of curated festivals worldwide with over 20 editions in countries like UK, France, Mexico and Belgium. KOSMICA also counts with other activities such as educational programmes, publishing and other curated activities. It has local offices in Berlin (Germany) and Mexico City (Mexico), with partner organisations in London (UK) and Montreal (Canada).
History
KOSMICA Institute was founded in 2011 by Berlin-based artist Nahum in partnership with The Art Catalyst in London. It started as ¨a series of galactic gatherings for earth-bound artists, space engineers, performers, astronomers, musicians and anyone interested, explore and share space in original ways. Every session is unique: bringing together the cosmically curious and culturally quirky space community.¨
Today KOSMICA organises regular festival with over 20 international editions and 180 guests from all around the globe. Its curated programmes have included topics such as feminism, queer culture, climate change, colonialism and art in outer space.
KOSMICA is endorsed by ITACCUS, the International Astronautical Federation Technical Committee for the Cultural Utilizations of Space.
“KOSMICA created an open, affable environment where the topics ranged from philosophy to the social importance of Star Trek.”
"KOSMICA opens new frontiers for artistic experimentation" - Rolling Stone Magazine
Participants
KOSMICA activities have put together an international network of artists, cultural practitioners and space professionals. Among the 180 participants are Kevin Fong, Tomás Saraceno, Ariel Guzik, Aleksandra Mir, Empress Stah, Yuri Suzuki, Honor Harger, Roger Malina, Marko Peljhan, Nelly Ben Hayoun, Katie Paterson, Agnes Meyer-Brandis, Kapwani Kiwanga, Bompas & Parr, Frederik De Wilde, Nicola Triscott, Anais Toneur, Carey Young, Christopher Riley, Dragan Živadinov, Sarah Jane Pell, Semiconductor, Angelo Vermaulen (Seeker), Richard Clar, Patricio Guzmán, Tania Candiani and Nahum.
Institutions and Collaborators
The KOSMICA Institute has collaborated with museums and institutions such as The Arts Catalyst (London), Foundation for Art and Creative Technology, FACT (Liverpool), Z33 (Hasselt), Oboro (Montreal), Laboratorio Arte Alameda (Mexico City), Centro de Cultura Digital (Mexico City), Centro Multimedia (Mexico City), Mexican Space Agency (Mexico), International Space University (Strasbourg), International Astronautical Federation, IAF (Paris), Hangar 1 (Berlin), La Colonie (Paris), amongst others.
KOSMICA Journeys
In 2017 KOSMICA partnered up with local organisations and governmental bodies to start a new strand of projects aimed at those who have flown away from their homes for safety and survival reasons. KOSMICA Journeys offers a series of activities for refugees and immigrants to use the outer space perspective and reframe our understanding of Earth as the home of humanity and all its life beyond nations and states.
KOSMICA Journeys started with a collaboration with Hangar 1 in Berlin. Over a month KOSMICA delivered weekly workshops at the refugee center located at the Tempelhofer Feld in Berlin.
Past Editions
2017, KOSMICA Paris, La Colonie, Paris, France
2016, KOSMICA Mexico, Cosmovitral, Laboratorio Arte Alameda, Cine Tonalá, Toluca & Mexico City, Mexico.
2015, KOSMICA Mexico, Laboratorio Arte Alameda, Cine Tonalá, Ovnibus, Mexico City, Mexico
2014, KOSMICA Mexico, Laboratorio Arte Alameda, Centro Multimedia - CENART, Centro de Cultura Digital, Mexico City, Mexico
2014, KOSMICA London, Bargehouse, London, UK
2013, KOSMICA Mexico, Laboratorio Arte Alameda, Centro Multimedia - CENART, Mexico City, Mexico
2013, KOSMICA London, The Arts Catalyst, London, UK
2013, KOSMICA Belgium, Z33, Hasselt, Belgium
2013, KOSMICA Paris, La Société de Curiosités, Paris, France
2012, KOSMICA London, The Arts Catalyst, London, UK
2012, KOSMICA Mexico, Laboratorio Arte Alameda, Centro Multimedia - CENART, Mexico City, Mexico
2012, KOSMICA Paris, La Société de Curiosités, Paris, France
2012, KOSMICA Liverpool, Foundation for Art and Technology (FACT), Liverpool, UK
2011, KOSMICA London, The Arts Catalyst, London UK
References
Works about outer space
Performance art festivals
Art and design organizations
International festivals | KOSMICA | [
"Astronomy",
"Engineering"
] | 979 | [
"Works about outer space",
"Art and design organizations",
"Design",
"Outer space"
] |
54,473,571 | https://en.wikipedia.org/wiki/Immersive%20commerce | Immersive commerce is an extension of e-commerce that focuses on improving customer experience by using augmented reality, virtual reality and immersive technology to create virtual smart stores from existing brick and mortar locations.
Rather than an iteration of traditional e-commerce, immersive commerce is a form of online shopping that blends physical elements of traditional stores (i.e. rows, shelves, racks, counters, etc.) with digital elements of traditional e-commerce web sites (i.e. mobile commerce, electronic funds transfer, supply chain management, digital marketing, online transaction processing, electronic data interchange, inventory management systems, automated data collection systems and CRM). Immersive commerce platforms give consumers the ability to browse and shop aisles of a virtual store using any online device.
References
E-commerce
User interface techniques
Augmented reality | Immersive commerce | [
"Technology"
] | 170 | [
"Information technology",
"E-commerce"
] |
54,473,907 | https://en.wikipedia.org/wiki/NGC%207059 | NGC 7059 is a nearby spiral galaxy located about 70 million light-years away in the constellation of Pavo. NGC 7059 was discovered by astronomer John Herschel on July 22, 1835.
See also
List of NGC objects (7001–7840)
NGC 224
References
External links
Spiral galaxies
Pavo (constellation)
7059
66784
Astronomical objects discovered in 1835 | NGC 7059 | [
"Astronomy"
] | 77 | [
"Constellations",
"Pavo (constellation)"
] |
54,474,084 | https://en.wikipedia.org/wiki/The%20Tissue-Culture%20King | The Tissue-Culture King (1926 in Cornhill Magazine and in The Yale Review, reprinted 1927 in Amazing Stories and many times afterwards) is a science fiction short story by biologist Julian Huxley.
The story tells of a biologist captured by an African tribe. It incorporates the idea of immortality based on reproduction from a tissue culture and genetic engineering, and an early mention of tin foil hats and their supposed anti-telepathic properties.
Plot
A group of explorers of Africa stumble upon a strange two-headed toad, and that leads them to meet an endocrinologist, Dr. Hascombe. Captured by an African tribe, Dr. Hascombe saves himself by using "magical" powers of modern biology.
Critical evaluation
Patrick Parrinder considers the story as an allegory to the servile place of science within a capitalist political world.
References
External links
"The Tissue-Culture King" at the Internet Archive
British science fiction
Science fiction short stories
Fiction about genetic engineering
1926 short stories
Works originally published in Amazing Stories
Africa in fiction
Works originally published in The Yale Review
Allegory | The Tissue-Culture King | [
"Engineering",
"Biology"
] | 218 | [
"Genetic engineering",
"Fiction about genetic engineering"
] |
54,474,095 | https://en.wikipedia.org/wiki/Contained%20earth | Contained earth (CE) is a structurally designed natural building material that combines containment, inexpensive reinforcement, and strongly cohesive earthen walls. CE is earthbag construction that can be calibrated for several seismic risk levels based on building soil strength and plan standards for adequate bracing.
There is a recognized need for structural understanding of alternative building materials. Construction guidelines for CE are currently under development, based on the New Zealand's performance-based code for adobe and rammed earth.
CE is differentiated from contained gravel (CG) or contained sand (CS) by the use of damp, tamped, cured cohesive fill. CE can be modular, built in poly-propylene rice bag material containers, or solid, built in mesh tubing that allows earthen fill to solidify between courses.
CG, filled with pumice or ordinary gravel and/ or small stones, is often used as water-resistant base walls under CE, which also provides an effective capillary break. Soil bags used mostly in horizontal applications by civil engineers contain loose fill which includes both CG and CS. CG courses, like soil bags, may contribute base isolation and/or vibration damping qualities, although out-of-plane strength needs research.
For clarity, earthbag built with a low cohesion fill, or filled with dry soil that does not solidify, is not CE but CS. Uncured CE also performs structurally like CS.
Earthbag variations
Builders used to working without engineers are proud of earthbag's unlimited variations. Few trainers discuss risk levels of building sites, or recommend accurate tests of soil strength, even though soil strength is a key factor of improved seismic performance for earthen walls.
Need for or use of metal components are disputed, including rebar hammered into walls and barbed wire between courses, although static friction of smooth bag-to-bag surfaces of heavy modular CE walls is 0.4 with no adhesion.
Engineering knowledge of earthbag has been growing. More is known about the performance of walls made with sand or dry or uncured soil than about the overwhelming majority of earthbag buildings which have used damp, cohesive soil fill. Reports based on tests of soil bags and loose or granular fill (or uncured fill) assumes that soil strength is less important to wall strength than bag fabric strength for. However, shear tests show clearly that stronger cured, cohesive fill increases contained earth wall strength substantially.
Earthbag for high risk environments
Earthbag developed gradually without structural analysis, first for small domes, then for vertical wall buildings of many shapes. Although domes passed structural testing in California, no structural information was extracted from tests of the inherently stable shapes. Builders borrowed guidelines for adobe to recommend plan details, but code developed in low seismic risk New Mexico does not address issues for higher risk areas. California's seismic risk levels are almost three times as high as New Mexico's, and risk worldwide rises much higher.
Earthbag is often tried after disasters in the developing world, including Sri Lanka's 2004 tsunami, Haiti's 2010 earthquake and Nepal's 2015 earthquake.
CE walls fail in shear tests when barbs flex or bend back or (with weak soil fill) by chipping cured bag fill. CS walls or uncured CE walls fail differently, by slitting bag fabric as barbs move through loose fill.
Because no earthbag buildings were seriously damaged by seismic motion up to 0.8 g in Nepal's 2015 quakes, Nepal's building code recognizes earthbag, although the code does not discuss soil strengths or improved reinforcement. Nepal requires buildings to resist 1.5 g risk although hazard maps show higher values. Better trainers assume the use of cohesive soil and barbed wire, and recommend vertical rebar, buttresses, and bond beams, but rule of thumb earthbag techniques should be differentiated from contained earth that follows more complete guidelines.
CE compared to New Zealand wall strengths
Earthquake damage results confirm the validity of New Zealand's detailed standards for non-engineered adobe and rammed earth which allow unreinforced buildings to 0.6 g force levels.
Although earthbag without specific guidelines may often be this strong, conventional adobe can have severe damage at levels below 0.2 g forces. Non-traditional earthbag built with barbed wire, barely cohesive soil and no rebar can have half the shear strength of NZ's unreinforced adobe. Somewhere between 0.3 and 0.6 g forces, CE guidelines become important.
Based on static shear testing (Stouter, P. May 2017):
The following approximate guidelines assume a single story of wide walls with 2 strands of 4 point barbed wire per course. Check NZS 4299 for bracing wall spacing and size of bracing walls and/ or buttresses. Vertical rebar must be spaced on center average and embedded in wall fill while damp. Follow NZS 4299 restrictions on building size, site slope, climate, and uses.
Discuss foundation concerns with an engineer, since NZS 4299 assumes a full reinforced concrete footing.
For comparison to NZS 4299 the following risk levels are based roughly on 0.2 second spectral acceleration (Ss) from 2% probability of exceedance in 50 years. Builders may refer to the Unified Facilities Handbook online for these values for some cities worldwide. These risk levels are based on ultimate strength, but deformation limits may require stiffer detailing or lower risk levels.
Medium strength soil: unconfined compressive strength
±0.75 g risk if 2 separate pieces of rebar are inserted, overlapped
1.6 g risk if an entire internal rebar extends from base to bond beam
Strong soil: unconfined compressive strength
±1.6 g risk if 2 separate pieces of rebar are inserted, overlapped
±2.1 g risk if a single rebar extends from base to bond beam
Additional research and engineering analysis is needed to create valid CE manuals.
References
Natural materials
Building materials | Contained earth | [
"Physics",
"Engineering"
] | 1,206 | [
"Natural materials",
"Building engineering",
"Construction",
"Materials",
"Building materials",
"Matter",
"Architecture"
] |
54,474,403 | https://en.wikipedia.org/wiki/LEDA%2083677 | LEDA 83677 is a lenticular galaxy located about 290 million light-years away in the constellation Coma Berenices. It is a member of the Coma cluster of galaxies. LEDA 83677 is also classified as a type 1 Seyfert galaxy. The core of the galaxy is emitting high-energy X-rays and ultraviolet light, probably caused by a massive black hole lurking in the core.
See also
NGC 4477
NGC 6814
References
External links
Lenticular galaxies
Coma Berenices
83677
Coma Cluster
Seyfert galaxies | LEDA 83677 | [
"Astronomy"
] | 119 | [
"Coma Berenices",
"Constellations"
] |
54,474,556 | https://en.wikipedia.org/wiki/Sampson%20flow | Sampson flow is defined as fluid flow through an infinitely thin orifice in the viscous flow regime for low Reynolds number. It is derived from an analytical solution to the Navier-Stokes equations. The below equation can be used to calculate the total volumetric flowrate through such an orifice:
Here, is the volumetric flowrate in , is the pressure difference in Pa, is the pore diameter in m, and is the fluid's dynamic viscosity in Pa·s. The flow can also be expressed as a molecular flux as:
Here, is the molecular flux in atoms/m2·sec, is the average of the pressures on either side of the orifice, is the Boltzmann constant, ( J/K), and is the absolute temperature in K.
Sampson flow is the macroscopic analog of effusion flow, which describes stochastic diffusion of molecules through an orifice much smaller than the mean-free-path of the gas molecules. For pore diameters on the order of the mean-free-path of the fluid, flow will occur with contributions from the molecular regime as well as the viscous regime, obeying the dusty gas model according to the following equation:
Here, is the total volumetric flowrate and is the volumetric flowrate according to the law of effusion. As it turns out, for many gasses, we notice equal contributions from molecular and viscous regimes when the pore size is significantly larger than the mean-free-path of the fluid, for nitrogen this occurs at a pore diameter of 393 nm, 6.0× larger than the mean-free-path.
References
Fluid dynamics | Sampson flow | [
"Chemistry",
"Engineering"
] | 342 | [
"Piping",
"Chemical engineering",
"Fluid dynamics"
] |
44,427,919 | https://en.wikipedia.org/wiki/Vitamin%20K-dependent%20protein | A Vitamin K-dependent protein (VKDP) is a protein that can bind calcium ions but only after being carboxylated at a certain glutamic residue. This carboxylation, said to activate the protein, is facilitated by some form of vitamin K1 or vitamin K2. The relevant part of a vitamin K-dependent protein is a Gla domain, and such a protein is informally called a Gla protein. Some Gla proteins have "Gla" in their name, for example Matrix Gla protein, but many don't, such as osteocalcin.
References
Proteins
Vitamin K | Vitamin K-dependent protein | [
"Chemistry"
] | 130 | [
"Biomolecules by chemical classification",
"Protein stubs",
"Biochemistry stubs",
"Molecular biology",
"Proteins"
] |
44,428,769 | https://en.wikipedia.org/wiki/Radio%20Science | Radio Science is a quarterly peer-reviewed scientific journal published by Wiley-Blackwell on behalf of the American Geophysical Union and co-sponsored by the International Union of Radio Science. It contains original scientific contributions on radio-frequency electromagnetic propagation and its applications (radio science). Its full aims and scope read:
Volumes for the years 1966 through 1968 were issued by the Environmental Science Services Administration (ESSA), the precursor of the National Oceanic and Atmospheric Administration (NOAA), in cooperation with the United States National Committee of the International Scientific Radio Union.
Abstracting and indexing
The journal is abstracted and indexed in:
According to the Journal Citation Reports, the journal has a 2023 impact factor of 1.6.
See also
Advances in Radio Science
References
External links
Academic journals established in 1966
English-language journals
American Geophysical Union academic journals
Wiley (publisher) academic journals
Wiley-Blackwell academic journals
Electrical and electronic engineering journals
Electromagnetism journals
Remote sensing journals | Radio Science | [
"Engineering"
] | 194 | [
"Electrical engineering",
"Electronic engineering",
"Electrical and electronic engineering journals"
] |
44,429,458 | https://en.wikipedia.org/wiki/Advances%20in%20Radio%20Science | Advances in Radio Science is a peer-reviewed open access scientific journal published by the German National Committee of the International Union of Radio Science. It covers radio science and radio-frequency engineering. It was established in 2003 and its current editors-in-chief is Ludger Klinkenbusch (Kiel University).
Abstracting and indexing
The journal is abstracted and indexed in:
According to the Journal Citation Reports, the journal has a 2023 impact factor of 2.2.
See also
Radio Science
References
External links
Electrical and electronic engineering journals
Academic journals established in 2003
Copernicus Publications academic journals
Creative Commons Attribution-licensed journals
Electromagnetism journals
English-German multilingual journals | Advances in Radio Science | [
"Engineering"
] | 143 | [
"Electrical engineering",
"Electronic engineering",
"Electrical and electronic engineering journals"
] |
44,429,959 | https://en.wikipedia.org/wiki/Temporal%20network | A temporal network, also known as a time-varying network, is a network whose links are active only at certain points in time. Each link carries information on when it is active, along with other possible characteristics such as a weight. Time-varying networks are of particular relevance to spreading processes, like the spread of information and disease, since each link is a contact opportunity and the time ordering of contacts is included.
Examples of time-varying networks include communication networks where each link is relatively short or instantaneous, such as phone calls or e-mails. Information spreads over both networks, and some computer viruses spread over the second. Networks of physical proximity, encoding who encounters whom and when, can be represented as time-varying networks. Some diseases, such as airborne pathogens, spread through physical proximity. Real-world data on time resolved physical proximity networks has been used to improve epidemic modeling. Neural networks and brain networks can be represented as time-varying networks since the activation of neurons are time-correlated.
Time-varying networks are characterized by intermittent activation at the scale of individual links. This is in contrast to various models of network evolution, which may include an overall time dependence at the scale of the network as a whole.
Applicability
Time-varying networks are inherently dynamic, and used for modeling spreading processes on networks. Whether using time-varying networks will be worth the added complexity depends on the relative time scales in question. Time-varying networks are most useful in describing systems where the spreading process on a network and the network itself evolve at similar timescales.
Let the characteristic timescale for the evolution of the network be , and the characteristic timescale for the evolution of the spreading process be . A process on a network will fall into one of three categories:
Static approximation – where . The network evolves relatively slowly, so the dynamics of the process can be approximated using a static version of the network.
Time-varying network – where . The network and the process evolve at comparable timescales so the interplay between them becomes important.
Annealed approximation – where . The network evolves relatively rapidly, so the dynamics of the process can be approximated using a time averaged version of the network.
The flow of data over the internet is an example for the first case, where the network changes very little in the fraction of a second it takes for a network packet to traverse it. The spread of sexually transmitted diseases is an example of the second, where the prevalence of the disease spreads in direct correlation to the rate of evolution of the sexual contact network itself. Behavioral contagion is an example of the third case, where behaviors spread through a population over the combined network of many day-to-day social interactions.
Representations
There are three common representations for time-varying network data.
Contact sequences – if the duration of interactions are negligible, the network can be represented as a set of contacts where and are the nodes and the time of the interaction. Alternatively, it can be represented as an edge list where each edge is a pair of nodes and has a set of active times .
Interval graphs – if the duration of interactions are non-negligible, becomes a set of intervals over which the edge is active.
Snapshots – time-varying networks can also be represented as a series of static networks, one for each time step.
Properties
The measures used to characterize static networks are not immediately transferable to time-varying networks. See Path, Connectedness, Distance, Centrality. However, these network concepts have been adapted to apply to time-varying networks.
Time respecting paths
Time respecting paths are the sequences of links that can be traversed in a time-varying network under the constraint that the next link to be traversed is activated at some point after the current one. Like in a directed graph, a path from to does not mean there is a path from to . In contrast to paths in static and evolving networks, however, time respecting paths are also non-transitive. That is to say, just because there is a path from to and from to does not mean that there is a path from to . Furthermore, time respecting paths are themselves time-varying, and are only valid paths during a specific time interval.
Reachability
While analogous to connectedness in static networks, reachability is a time-varying property best defined for each node in the network. The set of influence of a node is the set of all nodes that can be reached from via time respecting paths, note that it is dependent on the start time . The source set of a node is the set of all nodes that can reach via time respecting paths within a given time interval. The reachability ratio can be defined as the average over all nodes of the fraction of nodes within the set of influence of .
Connectedness of an entire network is less conclusively defined, although some have been proposed. A component may be defined as strongly connected if there is a directed time respecting path connecting all nodes in the component in both directions. A component may be defined as weakly connected if there is an undirected time respecting path connecting all nodes in the component in both directions. Also, a component may be defined as transitively connected if transitivity holds for the subset of nodes in that component.
Causal fidelity
Causal fidelity quantifies the goodness of the static approximation of a temporal network. Such a static approximation is generated by aggregating the edges of a temporal network over time. The idea of causal fidelity is to compare the number of paths between all node pairs in the temporal network (that is, all time respecting paths) with the number of paths between all nodes in the static approximation of the network. The causal fidelity is then defined by
.
Since in only time respecting paths are considered, , and consequently . A high causal fidelity means that the considered temporal network is well approximated by its static (aggregated) counterpart. If , then most node pairs that are reachable in the static representation are not connected by time respecting paths in the temporal network.
Latency
Also called temporal distance, latency is the time-varying equivalent to distance. In a time-varying network any time respecting path has a duration, namely the time it takes to follow that path. The fastest such path between two nodes is the latency, note that it is also dependent on the start time. The latency from node to node beginning at time is denoted by .
Centrality measures
Measuring centrality on time-varying networks involves a straightforward replacement of distance with latency. For discussions of the centrality measures on a static network see Centrality.
Closeness centrality is large for nodes that are close to all other nodes (i.e. have small latency for all )
Betweenness centrality is large for nodes that are often a part of the smallest latency paths between other pairs of nodes. It is defined as the ratio of the number of smallest latency paths from and that pass through to the total number of smallest latency paths from and
The time-varying nature of latency, specifically that it will become infinity for all node pairs as the time approaches the end of the network interval used, makes an alternative measure of closeness useful. Efficiency uses instead the reciprocal of the latency, so the efficiency approaches zero instead of diverging. Higher values for efficiency correspond to more central nodes in the network.
Temporal patterns
Time-varying network allow for analysis of explicit time dependent properties of the network. It is possible to extract recurring and persistent patterns of contact from time-varying data in many ways. This is an area of ongoing research.
Characteristic times of the system can be found by looking for distinct changes in a variable, such as the reachability ratio. For example, if one allows only a finite waiting time at all nodes in calculating latency, one can find interesting patterns in the resulting reachability ratio. For a mobile call network, the reachability ratio has been found to increase dramatically if one allows delays of at least two days, and for the airline network the same effect has been found at around 30 minutes. Moreover, the characteristic time scale of a temporal network is given by the mode of the distribution of shortest path durations. This distribution can be calculated using the reachability between all node pairs in the network.
Persistent patterns are ones that reoccur frequently in the system. They can be discovered by averaging over different across the time interval of the system and looking for patterns that reoccur over a specified threshold.
Motifs are specific temporal patterns that occur more often the expected in a system. The time-varying network of Facebook wall postings, for example, has higher frequency of chains, stars, and back and forth interactions that could be expected for a randomized network.
Egocentric Temporal motifs can be used to exploit temporal ego-networks. Due to their first-order complexity can be counted in large graphs in a reasonable execution time. For example, Longa et al. show how to use Egocentric Temporal Motifs for measuring distances among face-to-face interaction networks in different social contexts.
Detecting missing links
Dynamics
Time-varying networks allow for the analysis of an entirely new dimension of dynamic processes on networks. In cases where the time scales of evolution of the network and the process are similar, the temporal structure of time-varying networks has a dramatic impact on the spread of the process over the network.
Burstiness
The time between two consecutive events, for an individual node or link, is called the inter-event time. The distribution of inter-event times of a growing number of important, real-world, time-varying networks have been found to be bursty, meaning inter-event times are very heterogeneous – they have a heavy-tailed distribution. This translates to a pattern of activation where activity comes in bursts separated by longer stretches of inactivity.
Burstiness of inter-event times can dramatically slow spreading processes on networks, which has implications for the spread of disease, information, ideas, and computer viruses. However, burstiness can also accelerate spreading processes, and other network properties also have an effect on spreading speed. Real-world time-varying networks may thus promote spreading processes despite having a bursty inter-event time distribution.
Burstiness as an empirical quantity can be calculated for any sequence of inter-event times, , by comparing the sequence to one generated by a Poisson process. The ratio of the standard deviation, , to the mean, , of a Poisson process is 1. This measure compares to 1.
Burstiness varies from −1 to 1. B = 1 indicates a maximally bursty sequence, B = 0 indicates a Poisson distribution, and B = −1 indicates a periodic sequence.
See also
Complex contagion
Complex network
Epidemic model
Directed percolation
Dynamic network analysis
Exponential random graph models
Link-centric preferential attachment
Scale-free network
Percolation theory
References
Network theory | Temporal network | [
"Mathematics"
] | 2,202 | [
"Network theory",
"Mathematical relations",
"Graph theory"
] |
44,430,287 | https://en.wikipedia.org/wiki/Transformer%20oil%20testing | Transformer oil, a type of insulating and cooling oil used in transformers and other electrical equipment, needs to be tested periodically to ensure that it is still fit for purpose. This is because it tends to deteriorate over time. Testing sequences and procedures are defined by various international standards, many of them set by ASTM. Transformer oil testing consists of measuring breakdown voltage and other physical and chemical properties of samples of the oil, either in a laboratory or using portable test equipment on-site.
Motivation for testing
The transformer oil (insulation oil) of voltage transformers and current transformers fulfills the purpose of insulating as well as cooling. Thus, the dielectric quality of transformer oil is essential to secure operation of a transformer.
As transformer oil deteriorates through aging and moisture ingress, transformer oil should, depending on economics, transformer duty and other factors, be tested periodically. Electric utility companies have a vested interest in periodic oil testing because transformers represent a large proportion of their total assets. Through such testing, transformers' life can be substantially increased, thus delaying new investment of replacement transformer assets.
On-site testing
Recently time-consuming testing procedures in test labs have been replaced by on-site oil testing procedures. There are various manufacturers of portable oil testers. With low weight devices in the range of 20 to 40 kg, tests up to 100 kV rms can be performed and reported on-site automatically. Some of them are even battery-powered and come with accessories.
Breakdown voltage testing procedure
To assess the insulating property of dielectric transformer oil, a sample of the transformer oil is taken and its breakdown voltage is measured. The lower the resulting breakdown voltage, the poorer the quality of the transformer oil.
The transformer oil is filled in the vessel of the testing device. Two standard-compliant test electrodes with a typical clearance of 2.5 mm are surrounded by the dielectric oil.
A test voltage is applied to the electrodes and is continuously increased up to the breakdown voltage with a constant, standard-compliant slew rate of e.g. 2 kV/s.
At a certain voltage level breakdown occurs in an electric arc, leading to a collapse of the test voltage.
An instant after ignition of the arc, the test voltage is switched off automatically by the testing device. Ultra fast switch off is highly desirable, as the carbonisation due to the electric arc must be limited to keep the additional pollution as low as possible.
The transformer oil testing device measures and reports the root mean square value of the breakdown voltage.
After the transformer oil test is completed, the insulation oil is stirred automatically and the test sequence is performed repeatedly: typically 5 repetitions, depending on the standard.
As a result the breakdown voltage is calculated as mean value of the individual measurements.
Types of test
Color; e.g., ASTM D1500.
Dielectric breakdown voltage; e.g., D 877, ASTM D1816
Dissolved gas analysis; e.g., ASTM D3612
Dissolved metals; e.g., ASTM D7151
Flash point, fire point; e.g., ASTM D92
Interfacial tension; e.g. D 971
Furanic compounds; e.g., ASTM D5837
Karl Fischer moisture; e.g., ASTM D1533
Liquid power factor; e.g., ASTM D924
Neutralization number; e.g., ASTM D974
Oxidation inhibitor content; e.g., ASTM D2668
Polychlorinated biphenyls content; e.g., ASTM D4059
Relative density (specific gravity); e.g., D 1298, ASTM D1524
Resistivity; e.g., ASTM D1169
Visual examination; e.g., D1524
International transformer oil testing standards
VDE370-5/96
OVE EN60156
IEC 60156/97,
ASTM1816-04-1
ASTM1816-04-2
ASTM877-02
ASTM877-02B
AS1767.2.1
BS EN60156
NEN 10 156
NF EN60156
PA SEV EN60156
SABS EN60156
UNE EN60156
IS:6792
IS 335
See also
Electrical measurements
Severity factor
References
Electric transformers
Electrical tests | Transformer oil testing | [
"Engineering"
] | 922 | [
"Electrical engineering",
"Electrical tests"
] |
44,430,316 | https://en.wikipedia.org/wiki/Host%20adaptation | When considering pathogens, host adaptation can have varying descriptions. For example, in the case of Salmonella, host adaptation is used to describe the "ability of a pathogen to circulate and cause disease in a particular host population." Another usage of host adaptation, still considering the case of Salmonella, refers to the evolution of a pathogen such that it can infect, cause disease, and circulate in another host species.
Description
While there might be pathogens that can infect other hosts and cause disease, the inability to pervade, or spread, throughout the infected host species indicates that the pathogen is not adapted to that host species. In this case, the ability or lack thereof of a pathogen to adapt to its host environment is an indicator of the pathogen's fitness or virulence. If a pathogen has high fitness in the host environment, or is virulent, it will be able to grow and spread quickly within its host. Conversely, if the pathogen is not well adapted to its host environment, then it will not spread or infect the way a well adapted pathogen would.
Pathogens like Salmonella, which is a food borne pathogen, are able to adapt to the host environment and maintain virulence via several pathways. In a paper by Baumler et al. 1998, characters of Salmonella, such as its ability to cause intestinal infection were attributed to virulence factors like its ability to invade intestinal epithelial cells, induce neutrophil recruitment and interfere with the secretion of intestinal fluid. Phylogenetic analysis also revealed that many strains or lineages of Salmonella exist, which is advantageous for the pathogen because its genetic diversity can acts as fodder for natural selection to tinder with. For instance, if a particular Salmonella strain is more fit in the host stomach environment, compared to other Salmonella strains, then the former will be positively selected for and increase in prevalence. Eventually this strain will colonize and infect the stomach. The other less fit strains will be selected against and will thus not persist. Another major host adaptation on the part of Salmonella was its adaptation to host blood temperatures. Because Salmonella can thrive at the human host temperature, 98.6 degrees F, it is fit for the host environment and hence survives well in it. Adaptations like these are simple yet very effective ways of infecting hosts because they use the host's body and important feature of its body as a stepping stone in the infection process.
Another intestinal pathogen in the genus Cryptosporidium, which was not always a human pathogen, "recently" adapted to the human host environment. Numerous phylogenetic analyses in a paper by Xiao et al. 2002 indicated that the Cryptosporidium parvum bovine genotype and Cryptosporidium meleagridis were originally parasites of rodents and mammals, respectively. However, this parasite 'recently' expanded into humans. As was previously mentioned, the ability to survive in different host species is an adaptation that is highly advantageous to pathogens because it increases their chances for survival and circulation. Some pathogens can evolve to become resistant to the body's natural immune defenses and/or to outside interventions like drugs. For instance, Clostridioides difficile is the most frequent cause of nosocomial diarrhea worldwide, and reports in the early 2000s indicated the advent of a hypervirulent strain in North America and Europe. In study by Stabler et al. 2006, comparative phylogenomics (whole-genome comparisons using DNA microarrays combined with Bayesian phylogenies) were used to model the phylogeny of C. difficile. Phylogenetic analysis identified four distinct statistically significant 'clusters' making a hypervirulent clade, a toxin A− B+ clade, and two clades with human and animal isolates. Genetic differences between the four groups revealed significant findings related to virulence. The authors saw that hypervirulent strains had undergone various types of niche adaptation like antibiotic resistance, motility, adhesion, and enteric metabolism.
Some commensal organisms, or organisms that occur in the body naturally and benefit from living in the host without causing it harm or conferring any significant benefit, also have the potential to become pathogens. This specific type of commensal/pathogen hybrid is called an opportunistic pathogen. Not all commensals are opportunistic pathogens. However, opportunistic pathogens are commensals by nature. They are not harmful to the body when the body's immune system is functioning normally, but if the host immune system becomes compromised, or loses its ability to function at its full or near-full potential, opportunistic pathogens switch from being a commensal organism to a pathogen. This is where the name opportunistic pathogen comes from: they are only pathogens when the opportunity to infect the host is there. An example of an opportunistic pathogen is Candida albicans. Candida albicans is a type of fungus/yeast found in the intestines and mucous membranes (like the vagina and throat) of healthy humans. It is also found on the skin of healthy humans. In healthy humans- meaning humans with functioning immune systems- Candida will not cause infections. It will simply co-exist with the host. However, if a person receives chemotherapy or has HIV/AIDS, which weakens the immune system (thus compromising it), Candida albicans will cause infections. It can cause infections as innocuous as yeast infections or thrush and it can cause infections as serious as systemic candidiasis which is fatal in about 50% of cases. Though the mechanisms Candida albicans uses to switch from being a commensal to a pathogen are largely unknown, the reasons for its strength as a pathogen are broadly known. Candida has plenty of phenotypic and genotypic plasticity which means it generates change quickly. As a result of constant diversification, candida has many opportunities to make advantageous mutations. Additionally, Candida can change morphology. It can convert from the yeast for to the filamentous form and vice versa, depending on which stage of infection it is in. In the beginning stages of infection, Candida is more likely to be in the filamentous form because this allows it to adhere to and infect cells more efficiently. Other adaptations of the commensal pathogen include the ability to grow at host temperature, create biofilms, resist reactive oxygen species (ROS) created as part of the human immune response to fight off infection, adapt to different pHs (relevant for being carried in the blood in different parts of the body) and adapt to low nutrient or low glucose environments like the liver Because Candida albicans is very good at adapting to the fluctuating environments of the humans body (i.e. its changing temperature, pH, oxygen reactivity and more) candida albicans is a good pathogen.
Host adaptation can also be used in reference to the host. Hosts have the ability to adapt to protect themselves against pathogens. For instance, the innate and acquired immune responses are adaptations of the human body that exist for the sole purpose of warding off disease. Additionally, as was previously mentioned with the case of reactive oxygen species, the body has various other ways off warding off threats. Sexual reproduction is also a feature that humans and other sexually reproducing organisms have to protect themselves against pathogens. For instance, in what's called the red queen hypothesis, hosts are constantly shifting genetically via sexual reproduction in order to continue changing so pathogens have less of a chance to be well adjusted to the host. If the host keeps changing via gene shuffling in the form of reproduction, then hosts will have to continuously evolve with the host to keep up with its changes. This sets up a moving target for co-evolving pathogens.
References
Parasitism
Pathology | Host adaptation | [
"Biology"
] | 1,642 | [
"Parasitism",
"Symbiosis",
"Pathology"
] |
44,430,846 | https://en.wikipedia.org/wiki/Mucor%20plumbeus | Mucor plumbeus is a fungus in the family Mucoraceae (subphylum Mucoromycotina) that is very common, abundant and distributed worldwide. Mucor plumbeus is not known to be a plant or animal pathogen; however it is able to elicit an immune response in humans by activating the complement system. This species is commonly found in various types of soils over a range of pH, although alkaline soils seem more conducive to its growth. It is also known from the roots of wheat, oat and barley. In addition, M. plumbeus is a common fungal contaminant of indoor built environments. This species shares many similarities with M. racemosus, another fungus that belongs to the family Mucoraceae which is known to cause mucormycosis. Mucor plumbeus is a common spoilage agent of cheese, apples, apple cider and yogurt.
Morphology and reproduction
Mucor plumbeus produces columella with distinctive, darkly pigmented, finger-like apical projections. Sporangiophores (structures bearing asexual spores) exhibit sympodial and monopodial branching. The appearance of sporangia of M. plumbeus changes throughout development from hyaline at first becoming dark brown colour at maturity. Sporangiospores are spherical, ranging from 5–7 to 8–10 μm in diameter. Zygospores are also darkly coloured, though much larger than sporangiospores with an average diameter of approximately 85 μm. Zygospores are ornamented with short star-shaped spines (length of 3 μm). The mating system is heterothallic.
Growth on Czapek Yeast Extract Agar (CYA) and Malt Extract Agar (MEA) produces colonies at least 50 mm in diameter, often spreading across the petri dish. The mycelium appear colourless with an overall colour of pale to deep grey from the sporangia. Growth on G25N medium produces colonies 20–35 mm in diameter, which appear white to pale yellow brown. Mucor plumbeus spores are commonly airborne, which could explain their vast distribution. Chlamydospores have at times been found within sporangiophores.
Physiology
Mucor plumbeus colonies grown in culture were found to develop in the presence of ammonium chloride, L-histidine and urea, suggesting that these compounds are utilised as a nitrogen source. Mucor plumbeus can also use sucrose, D-mannose, D-sorbitol and citric acid as sources of carbon. Zygospores were found to be unable to grow in culture. Mucor plumbeus is capable of growing from to . The optimal temperature range for growth and sporulation to occur at was found to be . It does not grow at . Primary growth of M. plumbeus was found to be greatly suppressed by garlic extract in in-vivo growth studies. Sporulation can be suppressed by rubratoxin B. Mucor plumbeus can cause self inhibition of its germinating spores with the production of certain factors such as nonanoic acid. In a study conducted to determine the antifungal capabilities of different mixtures of cinnamon and clove oil against various important spoilage microorganisms, M. plumbeus was discovered to be amongst the most resistant organisms. This study also revealed that thymol has effective inhibitory action against M. plumbeus. In nature, M. plumbeus can be found in soils with a wide range in pH - particularly into the alkaline range. The minimum water activity (aw) for growth was reported to be 0.93. The growth of M. plumbeus varied with different gas concentrations. Growth in N was 80% of that in air. Growth also occurred in an atmosphere of more than 97% CO with trace amounts of O. Growth on cheddar cheese in an atmosphere of: 20% CO and 5% O was 50% of that in air; 20% CO and 1% O was 40% of that in air; 40% CO and 5% O was 50% of that in air; 40% CO and 1% O was 30% of that in air.
Symbiotic interactions
Hyphae of Mucor plumbeus have been found to be invaded by the hyperparasitic fungi Trichoderma viride and Synchephalis californica. In addition, Mucor plumbeus produces a gas that stimulates the growth of Phytophthora citrophthora, a plant pathogen. The presence of M. plumbeus stimulates the fruiting of Pilobolus kleinii due to the production of ammonia.
Health implications
As of yet, there have not been any reported cases of mycosis associated with M. plumbeus. However, studies have revealed that the spores of M. plumbeus have the ability to activate the complement system in humans via the alternative pathway. In addition, studies involving various complement proteins on fungal surfaces suggest that M. plumbeus spores can activate all pathways of the complement system. Mucor plumbeus is not known to produce any mycotoxins.
Distribution
Mucor plumbeus is distributed worldwide. Samples of M. plumbeus have been collected in numerous countries: as far north as Germany, Austria, Switzerland; as far east as Philippines, Indonesia; as far west as California and far south as South Africa. It is found in dust, soil and hypersaline water. Mucor plumbeus tolerates many soil types: including grassland, desert soils and heathland and has been isolated from the roots of alfalfa, oats, barley, Holcus mollis and other Australian heathland plants. In addition, it has been isolated from bird feathers, hay, decomposing plant debris, dung from different animals, fresh water, wood pulp, beech bark, wood timbers used in a copper mine, seeds of wheat and oat, and pecans. In the indoor built environment, M. plumbeus has been isolated from HVAC filters and has been detected in hospital air. In addition, M. plumbeus has been found to be associated with mould growth on concrete and other floor related materials and house dust. It is also known from foods such as meat, nuts and cereals, and has been isolated in low levels from black rice in Thailand, soybeans in the Philippines and from coriander in Indonesia.
Chemistry
A range of polysaccharides have been found in the extracellular and intracellular compartments of M. plumbeus including fucose, glucose, galactose and mannose. Glucuronic acid, a carbohydrate with a similar structure to glucose, is located specifically in the extracellular region of M. plumbeus. The monosaccharide glucosamine was found only in the intracellular regions of M. plumbeus. Mucor plumbeus has the ability to detoxify pentachlorophenol and has been used in the biotransformation of other products. Incubation of M. plumbeus with the natural product maalioxide produces three metabolites (1,7 and 9 β-hydroxymaalioxide). Mucor plumbeus activity towards camphorquinone is stereoselective. Extracts of Mucor plumbeus have shown acetylcholinesterase enzyme inhibition activity. Mucor plumbeus is able to biocatalyze the hydroxylation of terpenes and steroids by cytochrome p450 enzymes in the presence of O and cofactor NADPH. Mucor plumbeus also transforms sesquiterpene into a series of 12 degradation products of 10,15-epoxidation. As well, squamulosone (aromadendr-1(10)-en-9-one) is biotransformed by M. plumbeus to yield an array of terpenes.
References
External links
Index Fungorum
USDA ARS Fungal Database
Fungi described in 1878
Mucoraceae
Fungus species
Taxa named by Hermann Friedrich Bonorden | Mucor plumbeus | [
"Biology"
] | 1,708 | [
"Fungi",
"Fungus species"
] |
44,431,245 | https://en.wikipedia.org/wiki/Efficiency%20%28network%20science%29 | In network science, the efficiency of a network is a measure of how efficiently it exchanges information and it is also called communication efficiency. The underlying idea (and main assumption) is that the more distant two nodes are in the network, the less efficient their communication will be. The concept of efficiency can be applied to both local and global scales in a network. On a global scale, efficiency quantifies the exchange of information across the whole network where information is concurrently exchanged. The local efficiency quantifies a network's resistance to failure on a small scale. That is the local efficiency of a node characterizes how well information is exchanged by its neighbors when it is removed.
Definition
The definition of communication efficiency assumes that the efficiency is inversely proportional to the distance, so in mathematical terms
where is the pairwise efficiency of nodes in network and is their distance.
The average communication efficiency of the network is then defined as the average over the pairwise efficiencies:
where denotes the number of nodes in the network.
Distances can be measured in different ways, depending on the type of networks. The most natural distance for unweighted networks is the length of a shortest path between a nodes and , i.e. a shortest path between is a path with minimum number of edges and the number of edges is its length. Observe that if then —and that is why the sum above is over — while if there is no path connecting and , and their pairwise efficiency is zero. Being a count, for and so is bounded between 0 and 1, i.e. it is a normalised descriptor.
Weighted networks
The shortest path distance can also be generalised to weighted networks, see the weighted shortest path distance, but in this case and the average communication efficiency needs to be properly normalised in order to be comparable among different networks.
In the authors proposed to normalise dividing it by the efficiency of an idealised version of the network :
is the "ideal" graph on nodes wherein all possible edges are present. In the unweighted case every edge has unitary weight, is a clique, a full network, and . When the edges are weighted, a sufficient condition (for having a proper normalisation, i.e. ) on the distances in the ideal network, called this time , is
for . should be known (and different from zero) for all node pairs.
A common choice is to take them as the geographical or physical distances in spatial networks or as the maximum cost over all links, e.g. where indicates the maximum interaction strength in the network. However, in the authors highlight the issues of these choices when dealing with real world networks, which are characterised by heterogeneous structure and flows. For instance, choosing makes the global measure very sensitive to outliers in the distribution of weights and tends to under-estimate the actual efficiency of a network. The authors also propose a normalising procedure, i.e. a way for building using all and only the information contained in the edge weights (and no other meta-data such as geographical distances), which is statistically robust and physically grounded.
Efficiency and small-world behaviour
The global efficiency of a network is a measure comparable to , rather than just the average path length itself. The key distinction is that, while measures efficiency in a system where only one packet of information is being moved through the network, measures the efficiency of parallel communication, that is when all the nodes are exchanging packets of information with each other concurrently.
A local average of pairwise communication efficiencies can be used as an alternative to the clustering coefficient of a network. The local efficiency of a network is defined as:
where is the local subgraph consisting only of a node 's immediate neighbors, but not the node itself.
Applications
Broadly speaking, the efficiency of a network can be used to quantify small world behavior in networks. Efficiency can also be used to determine cost-effective structures in weighted and unweighted networks. Comparing the two measures of efficiency in a network to a random network of the same size to see how economically a network is constructed. Furthermore, global efficiency is easier to use numerically than its counterpart, path length.
For these reasons the concept of efficiency has been used across the many diverse applications of network science.
Efficiency is useful in analysis of man-made networks such as transportation networks and communications networks. It is used to help determine how cost-efficient a particular network construction is, as well as how fault tolerant it is. Studies of such networks reveal that they tend to have high global efficiency, implying good use of resources, but low local efficiency. This is because, for example, a subway network is not closed, and passengers can be re-routed, by buses for example, even if a particular line in the network is down.
Beyond human constructed networks, efficiency is a useful metric when talking about physical biological networks. In any facet of biology, the scarcity of resource plays a key role, and biological networks are no exception. Efficiency is used in neuroscience to discuss information transfer across neural networks, where the physical space and resource constraints are a major factor. Efficiency has also been used in the study of ant colony tunnel systems, which are usually composed of large rooms as well as many sprawling tunnels. This application to ant colonies is not too surprising because the large structure of a colony must serve as a transportation network for various resources, most namely food.
References
Network theory | Efficiency (network science) | [
"Mathematics"
] | 1,101 | [
"Network theory",
"Mathematical relations",
"Graph theory"
] |
44,431,852 | https://en.wikipedia.org/wiki/Cyclooctatetraenide%20anion | In chemistry, the cyclooctatetraenide anion or cyclooctatetraenide, more precisely cyclooctatetraenediide, is an aromatic species with a formula of [C8H8]2− and abbreviated as COT2−. It is the dianion of cyclooctatetraene. Salts of the cyclooctatetraenide anion can be stable, e.g., Dipotassium cyclooctatetraenide or disodium cyclooctatetraenide. More complex coordination compounds are known as cyclooctatetraenide complexes, such as the actinocenes.
The structure is a planar symmetric octagon stabilized by resonance, meaning each atom bears a charge of −. The length of the bond between carbon atoms is 1.432 Å. There are 10 π electrons. The structure can serve as a ligand with various metals.
List of salts
See also
Tropylium ion
Cyclopentadienyl anion
References
Simple aromatic rings
Anions
Non-benzenoid aromatic carbocycles | Cyclooctatetraenide anion | [
"Physics",
"Chemistry"
] | 237 | [
"Ions",
"Matter",
"Anions"
] |
44,431,955 | https://en.wikipedia.org/wiki/Partial%20dominance%20hypothesis | In genetics, the partial dominance hypothesis states that inbreeding depression is the result of the frequency increase of homozygous deleterious recessive or partially recessive alleles. The hypothesis can be explained by looking at a population that is divided into a large number of separately inbred lines. Deleterious alleles will eventually be eliminated from some lines and become fixed in other lines, while some lines disappear because of fixation of deleterious alleles. This will cause an overall decline in population and trait value, but then increase to a trait value that is equal to or greater than the trait value in the original population. Crossing inbred lines restores fitness in the overdominance hypothesis and a fitness increase in the partial dominance hypothesis.
References
Genetics | Partial dominance hypothesis | [
"Biology"
] | 158 | [
"Genetics"
] |
44,432,122 | https://en.wikipedia.org/wiki/Rittenhouse%20Medal | The Rittenhouse Medal is awarded by the Rittenhouse Astronomical Society for outstanding achievement in the science of Astronomy. The medal was one of those originally minted to commemorate the Bi-Centenary of the birth of David Rittenhouse on April 8, 1932. In 1952 the Society decided to establish a silver medal to be awarded to astronomers for noteworthy achievement in astronomical science. The silver medal is cast from the die (obverse) used for the Bi-Centennial Rittenhouse Medal.
See also
List of astronomy awards
References
Astronomy prizes
Awards established in 1932
1932 establishments in the United States | Rittenhouse Medal | [
"Astronomy",
"Technology"
] | 118 | [
"Science and technology awards",
"Astronomy prizes"
] |
44,432,370 | https://en.wikipedia.org/wiki/Woeseian%20revolution | The Woeseian revolution was the progression of the phylogenetic tree of life concept from two main divisions, known as the Prokarya and Eukarya, into three domains now classified as Bacteria, Archaea, and Eukaryotes. The discovery of the new domain stemmed from the work of biophysicist Carl Woese in 1977 from a principle of evolutionary biology designated as Woese's dogma. It states that the evolution of ribosomal RNA (rRNA) was a necessary precursor to the evolution of modern life forms. Although the three-domain system has been widely accepted, the initial introduction of Woese’s discovery received criticism from the scientific community.
Phylogenetic implications
The basis of phylogenetics was limited by the technology of the time, which led to a greater dependence on phenotypic classification before advances that would allow for molecular organization methods. This was a major reason why the dichotomy of all living things, being either animal or plant in nature, was deemed an acceptable theory. Without truly understanding the genetic implication of each organismal classification in phylogenies via nucleic acid sequencing of shared molecular material, the phylogenetic tree of life and other such phylogenies would no doubt be incorrect. Woese’s advances in molecular sequencing and phylogenetic organization allowed for a better understanding of the three domains of life - the Bacteria, Archaea, and Eukaryotes. Regarding their varying types of shared rRNA, the small subunit rRNA was deemed as the best molecule to sequence to distinguish phylogenetic relationships because of its relatively small size, ease of isolation, and universal distribution.
Controversy
This reorganization caused an initial pushback: it wasn't accepted until nearly a decade after its publication. Possible factors that led to initial criticisms of his discovery included Woese's oligonucleotide cataloging, of which he was one of "only two or three people in the world" to be able to execute this method, let alone read the films. Further, Woese's background was in physics, whereas most of the research was being done in microbiology.
References
Further reading
Biological classification
High-level systems of taxonomy
Carl Woese | Woeseian revolution | [
"Biology"
] | 436 | [
"nan"
] |
44,432,406 | https://en.wikipedia.org/wiki/LeRoy%20E.%20Doggett%20Prize | The LeRoy E. Doggett Prize is Awarded biennially by the Historical Astronomy Division of the American Astronomical Society for individuals who have significantly influenced the field of the history of astronomy by a career-long effort. The prize is a memorial to LeRoy Doggett, who was an active and highly regarded member of the Division and was serving as Secretary-Treasurer at the time of his untimely death.
See also
List of astronomy awards
References
Astronomy prizes
American science and technology awards | LeRoy E. Doggett Prize | [
"Astronomy",
"Technology"
] | 95 | [
"Science and technology awards",
"Science award stubs",
"Astronomy prizes",
"Astronomy stubs"
] |
44,432,474 | https://en.wikipedia.org/wiki/Chambliss%20Astronomical%20Writing%20Award | The Chambliss Astronomical Writing Award is awarded by the American Astronomical Society for astronomy writing for an academic audience, specifically textbooks at either the upper-division undergraduate level or the graduate level. Books suitable for this award must be currently available in North America. A single gold medal will be given, and if the winning book has multiple authors, the $1,000 monetary award will be divided, and multiple certificates will be issued.
References
See also
List of astronomy awards
Astronomy prizes
American science and technology awards
Science communication awards
Science writing awards
American education awards | Chambliss Astronomical Writing Award | [
"Astronomy",
"Technology"
] | 111 | [
"Astronomy prizes",
"Science writing awards",
"Science award stubs",
"Science communication awards",
"Science and technology awards"
] |
44,432,921 | https://en.wikipedia.org/wiki/Amicus%20Therapeutics | Amicus Therapeutics, Inc. is a public American biopharmaceutical company based in Philadelphia, PA. The company went public in 2007 under the NASDAQ trading symbol FOLD. This followed a 2006 planned offering and subsequent withdrawal, which would have established the trading symbol as AMTX Prior to their IPO, Amicus was funded by a variety of venture capital firms including Radius Ventures, Canaan Partners and New Enterprise Associates.
History
The therapeutic focus of Amicus is on rare and orphan diseases, particularly disorders collectively called lysosomal storage disorders. The company has focused on pharmacological chaperones and enzyme replacement therapy.
In 2008, the company expanded from its single site in New Jersey to a second research site in San Diego.
In late 2009, the company faced a major financial setback with the termination of a multi-year collaboration agreement with Shire for its lead compound, migalastat, and two other products. Amicus cut 20% of its workforce.
The next year, the company signed an exclusive license agreement with GlaxoSmithKline for migalastat; GSK paid $60 million in upfront and equity payments while promising up to $170 million to help develop their products, GSK terminated the arrangement in 2013.
In November 2013, Amicus acquired competitor Callidus Biopharma for its enzyme replacement therapy treatment for Pompe disease.
In September 2015, the company acquired Scioderm for $229 million in cash and stock, with potentially $618 million more in biodollars. Scioderm had a drug in Phase III trials for epidermolysis bullosa; additionally, if the drug was approved the FDA would give its owner a priority review voucher, which itself can be sold to another company. That drug failed its Phase III trial in 2017 and Amicus abandoned it. It had paid out around half of the milestones to Scioderm's shareholders prior to closing down the program.
Also in September 2015, Amicus announced that it would submit a new drug application (NDA) for accelerated approval of migalastat to the FDA by the end of 2015. An FDA committee recommended approval in April 2016, but the FDA rejected the application in November for having insufficient data in November 2016. The drug was approved in the European Union in May 2016.
In 2016 Amicus acquired MiaMed which was working on drugs to treat CDKL5 deficiency; Amicus paid $1.8M in cash and around $4.7M in stock, with $83M in biodollars.
After Scott Gottlieb became FDA commissioner in 2017, the CEO of Amicus began lobbying him directly for the FDA to accept the NDA and in February 2018 the FDA accepted it and promised a response by August 2018.
In September 2018, Amicus announced that it had acquired Celenex, which had ten early stage gene therapies. Amicus paid $100 million upfront and could pay an additional $352 million if developmental milestones are achieved.
References
2002 establishments in New Jersey
Drug discovery companies
Pharmaceutical companies based in New Jersey
Gene therapy
Biotechnology companies of the United States
Companies listed on the Nasdaq | Amicus Therapeutics | [
"Chemistry",
"Engineering",
"Biology"
] | 650 | [
"Drug discovery companies",
"Gene therapy",
"Genetic engineering",
"Drug discovery"
] |
44,433,271 | https://en.wikipedia.org/wiki/Space%20Flight%20Award | The Space Flight Award is an award given by the American Astronautical Society most years since 1955. It is presented to "the person whose outstanding efforts and achievements have contributed most significantly to the advancement of space flight and space exploration". The Society refers to the Space Flight Award as its "highest award".
See also
List of space technology awards
References
Spaceflight
Awards of the American Astronautical Society | Space Flight Award | [
"Astronomy"
] | 80 | [
"Spaceflight",
"Outer space"
] |
44,433,500 | https://en.wikipedia.org/wiki/Gas%20hydrate%20stability%20zone | Gas hydrate stability zone, abbreviated GHSZ, also referred to as methane hydrate stability zone (MHSZ) or hydrate stability zone (HSZ), refers to a zone and depth of the marine environment at which methane clathrates naturally exist in the Earth's crust.
Description
Gas hydrate stability primarily depends upon temperature and pressure, however other variables such as gas composition and ionic impurities in water influence stability boundaries. The existence and depth of a hydrate deposit is often indicated by the presence of a bottom-simulating reflector (BSR). A BSR is a seismic reflection indicating the lower limit of hydrate stability in sediments due to the different densities of hydrate saturated sediments, normal sediments and those containing free gas.
Limits
The upper and lower limits of the HSZ, as well as its thickness, depend upon the local conditions in which the hydrate occurs. The conditions for hydrate stability generally restrict natural deposits to polar regions and deep oceanic regions. In polar regions, due to low temperatures, the upper limit of the hydrate stability zone occurs at a depth of approximately 150 meters.1 The maximal depth of the hydrate stability zone is limited by the geothermal gradient. Along continental margins the average thickness of the HSZ is about 500 m. The upper limit in oceanic sediments occurs when bottom water temperatures are at or near 0 °C, and at a water depth of approximately 300 meters.1 The lower limit of the HSZ is bounded by the geothermal gradient. As depth below seafloor increases, the temperature eventually becomes too high for hydrates to exist. In areas of high geothermal heat flow, the lower limit of the HSZ may become shallower, therefore decreasing the thickness of the HSZ. Conversely, the thickest hydrate layers and widest HSZ are observed in areas of low geothermal heat flow. Generally, the maximum depth of HSZ extension is 2000 meters below the Earth's surface.1,3 Using the location of a BSR, as well as the pressure-temperature regimen necessary for hydrate stability, the HSZ may be used to determine geothermal gradients.2
Transport
If processes such as sedimentation or subduction transport hydrates below the lower limit of the HSZ, the hydrate becomes unstable and disassociates, releasing gas. This free gas may become trapped beneath the overlying hydrate layer, forming gas pockets, or reservoirs. The pressure from the presence of gas reservoirs impacts the stability of the hydrate layer. If this pressure is substantially changed, the stability of the methane layer above will be altered and may result in significant destabilization and disassociation of the hydrate deposit. Landslides of rock or sediment above the hydrate stability zone may also impact the hydrate stability. A sudden decrease in pressure can release gasses or destabilize portions of the hydrate deposit. Changing atmospheric and oceanic temperatures may impact the presence and depth of the hydrate stability zone, however, is still uncertain to what extent. In oceanic sediments, increasing pressure due to a rise in sea level may offset some of the impact of increasing temperature upon the hydrate stability equilibrium.1
References
Clathrate hydrates
Hydrates
Hydrocarbons
Methane
Oceanographical terminology
Physical oceanography | Gas hydrate stability zone | [
"Physics",
"Chemistry"
] | 669 | [
"Hydrocarbons",
"Applied and interdisciplinary physics",
"Methane",
"Hydrates",
"Organic compounds",
"Physical oceanography",
"Clathrates",
"Clathrate hydrates",
"Greenhouse gases"
] |
44,433,562 | https://en.wikipedia.org/wiki/AAAS%20Philip%20Hauge%20Abelson%20Prize | The AAAS Philip Hauge Abelson Prize is awarded by The American Association for the Advancement of Science for public servants, recognized for sustained exceptional contributions to advancing science or scientists, whose career has been distinguished both for scientific achievement and for other notable services to the scientific community. The prize is named after nuclear physicist Philip Abelson.The award consists of an engraved medallion and an honorarium of $5,000.
See also
AAAS Award for Science Diplomacy
AAAS Award for Scientific Freedom and Responsibility
AAAS Prize for Behavioral Science Research
Newcomb Cleveland Prize
References
Awards established in 1990
Science and technology awards
Philip Hauge Abelson Prize
American science and technology awards | AAAS Philip Hauge Abelson Prize | [
"Technology"
] | 131 | [
"Science and technology awards"
] |
44,433,870 | https://en.wikipedia.org/wiki/Quantum%20complex%20network | Quantum complex networks are complex networks whose nodes are quantum computing devices. Quantum mechanics has been used to create secure quantum communications channels that are protected from hacking. Quantum communications offer the potential for secure enterprise-scale solutions.
Motivation
In theory, it is possible to take advantage of quantum mechanics to create secure communications using features such as quantum key distribution is an application of quantum cryptography that enables secure communications Quantum teleportation can transfer data at a higher rate than classical channels.
History
Successful quantum teleportation experiments in 1998. Prototypical quantum communication networks arrived in 2004. Large scale communication networks tend to have non-trivial topologies and characteristics, such as small world effect, community structure, or scale-free.
Concepts
Qubits
In quantum information theory, qubits are analogous to bits in classical systems. A qubit is a quantum object that, when measured, can be found to be in one of only two states, and that is used to transmit information. Photon polarization or nuclear spin are examples of binary phenomena that can be used as qubits.
Entanglement
Quantum entanglement is a physical phenomenon characterized by correlation between the quantum states of two or more physically separate qubits. Maximally entangled states are those that maximize the entropy of entanglement. In the context of quantum communication, entangled qubits are used as a quantum channel.
Bell measurement
Bell measurement is a kind of joint quantum-mechanical measurement of two qubits such that, after the measurement, the two qubits are maximally entangled.
Entanglement swapping
Entanglement swapping is a strategy used in the study of quantum networks that allows connections in the network to change. For example, given 4 qubits, A, B, C and D, such that qubits C and D belong to the same station, while A and C belong to two different stations, and where qubit A is entangled with qubit C and qubit B is entangled with qubit D. Performing a Bell measurement for qubits A and B, entangles qubits A and B. It is also possible to entangle qubits C and D, despite the fact that these two qubits never interact directly with each other. Following this process, the entanglement between qubits A and C, and qubits B and D are lost. This strategy can be used to define network topology.
Network structure
While models for quantum complex networks are not of identical structure, usually a node represents a set of qubits in the same station (where operations like Bell measurements and entanglement swapping can be applied) and an edge between node and means that a qubit in node is entangled to a qubit in node , although those two qubits are in different places and so cannot physically interact. Quantum networks where the links are interaction terms instead of entanglement are also of interest.
Notation
Each node in the network contains a set of qubits in different states. To represent the quantum state of these qubits, it is convenient to use Dirac notation and represent the two possible states of each qubit as and . In this notation, two particles are entangled if the joint wave function, , cannot be decomposed as
where represents the quantum state of the qubit at node i and represents the quantum state of the qubit at node j.
Another important concept is maximally entangled states. The four states (the Bell states) that maximize the entropy of entanglement between two qubits can be written as follows:
Models
Quantum random networks
The quantum random network model proposed by Perseguers et al. (2009) can be thought of as a quantum version of the Erdős–Rényi model. In this model, each node contains qubits, one for each other node. The degree of entanglement between a pair of nodes, represented by , plays a similar role to the parameter in the Erdős–Rényi model in which two nodes form a connection with probability , whereas in the context of quantum random networks, refers to the probability of converting an entangled pair of qubits to a maximally entangled state using only local operations and classical communication.
Using Dirac notation, a pair of entangled qubits connecting the nodes and is represented as
For , the two qubits are not entangled:
and for , we obtain the maximally entangled state:
.
For intermediate values of , , any entangled state is, with probability , successfully converted to the maximally entangled state using LOCC operations.
One feature that distinguishes this model from its classical analogue is the fact that, in quantum random networks, links are only truly established after they are measured, and it is possible to exploit this fact to shape the final state of the network. For an initial quantum complex network with an infinite number of nodes, Perseguers et al. showed that, the right measurements and entanglement swapping, make it possible to collapse the initial network to a network containing any finite subgraph, provided that scales with as , where . This result is contrary to classical graph theory, where the type of subgraphs contained in a network is bounded by the value of .
Entanglement percolation
Entanglement percolation models attempt to determine whether a quantum network is capable of establishing a connection between two arbitrary nodes through entanglement, and to find the best strategies to create such connections.
Cirac et al. (2007) applied a model to complex networks by Cuquet et al. (2009), in which nodes are distributed in a lattice or in a complex network, and each pair of neighbors share two pairs of entangled qubits that can be converted to a maximally entangled qubit pair with probability . We can think of maximally entangled qubits as the true links between nodes. In classical percolation theory, with a probability that two nodes are connected, has a critical value (denoted by ), so that if a path between two randomly selected nodes exists with a finite probability, and for the probability of such a path existing is asymptotically zero. depends only on the network topology.
A similar phenomenon was found in the model proposed by Cirac et al. (2007), where the probability of forming a maximally entangled state between two randomly selected nodes is zero if and finite if . The main difference between classical and entangled percolation is that, in quantum networks, it is possible to change the links in the network, in a way changing the effective topology of the network. As a result, depends on the strategy used to convert partially entangled qubits to maximally connected qubits. With a naïve approach, for a quantum network is equal to for a classic network with the same topology. Nevertheless, it was shown that is possible to take advantage of quantum swapping to lower both in regular lattices and complex networks.
See also
Erdős–Rényi model
Gradient network
Network dynamics
Network topology
Quantum key distribution
Quantum teleportation
References
External links
LOCC operations
Network theory
Quantum information theory | Quantum complex network | [
"Mathematics"
] | 1,453 | [
"Network theory",
"Mathematical relations",
"Graph theory"
] |
44,434,900 | https://en.wikipedia.org/wiki/Australian%20Sport%20Aviation%20Confederation | Australian Sport Aviation Confederation is the governing body for the sport of Air sports in Australia.
History
Structure
The national body has eight state member associations:
Australian Aerobatic Club
Australian Ballooning Federation
Australian Parachute Federation
Hang Gliding Federation of Australia
Gliding Federation of Australia
Model Aeronautical Association of Australia
References
External links
1989 establishments in Australia
Sports organizations established in 1989
Sports governing bodies in Australia
Aviation organisations based in Australia
Fédération Aéronautique Internationale | Australian Sport Aviation Confederation | [
"Engineering"
] | 83 | [
"Fédération Aéronautique Internationale",
"Aeronautics organizations"
] |
44,435,343 | https://en.wikipedia.org/wiki/Checkout%20divider | A checkout divider is a small sign or bar meant for placement between items on a conveyor belt at a checkout in a supermarket or other retail store. Its purpose is to separate one customer's items from another customer's.
Checkout dividers are usually next to the conveyor belt on the side where the cashier is sitting or standing. Most checkout dividers display the store's name or some advertising.
Checkout dividers have been the subject of numerous internet debates, mainly regarding who is responsible for placing the checkout dividers.
References
See also
Bagger
Retail store elements
Etiquette by situation | Checkout divider | [
"Technology"
] | 129 | [
"Components",
"Retail store elements"
] |
44,436,398 | https://en.wikipedia.org/wiki/Kosmos%202499 | Kosmos 2499 was a Russian satellite orbiting the Earth, before breaking up on January 4, 2023.
Mission
The satellite was launched on May 23, 2014, from Plesetsk, Russia on a Rokot/Briz-KM launch vehicle along with 3 Rodnik-S satellites. Following launch the spacecraft was provisionally described by the NASA Orbital Debris Program Office as Object E until its identity was confirmed. USSPACECOM tracked it under satellite catalog number 39765.
Some reports have speculated, based on its unusual powered maneuvers, that it may be an experimental anti-satellite weapon, satellite maintenance vehicle, or collector of space debris. Chatham House research director and space security expert Patricia Lewis stated that "whatever it is, [Object 2014-028E] looks experimental."
According to an article published on the official Moscow Institute of Physics and Technology website, congratulating the developers on the successful launch and deployment, the satellite is designed to test experimental plasma propulsion engines/ion thrusters, designed by the JSC Reshetnev Company and the Keldysh Research Center. The article states that the engines are part of a new generation of Hall effect thrusters and are designed to be able to shift a spacecraft on an east-west and north-south axis using a fraction of the energy required by current propulsion systems.
Post-mission
In December 2021 USSPACECOM catalogued 18 debris associated with Kosmos 2499.
On February 6, 2023, US Space Command confirmed that the breakup of Kosmos 2499 had occurred on January 4, 2023, at 03:57 UTC. They catalogued 85 associated pieces, orbiting at altitude.
See also
2014 in spaceflight
Cold War II
Istrebitel Sputnikov
X-37B
References
External links
Kosmos satellites
Spacecraft launched in 2014
2014 in Russia
Spacecraft that broke apart in space | Kosmos 2499 | [
"Technology"
] | 379 | [
"Space debris",
"Spacecraft that broke apart in space"
] |
44,436,862 | https://en.wikipedia.org/wiki/Quadrature%20based%20moment%20methods | Quadrature-based moment methods (QBMM) are a class of computational fluid dynamics (CFD) methods for solving Kinetic theory and is optimal for simulating phases such as rarefied gases or dispersed phases of a multiphase flow. The smallest "particle" entities which are tracked may be molecules of a single phase or granular "particles" such as aerosols, droplets, bubbles, precipitates, powders, dust, soot, etc. Moments of the Boltzmann equation are solved to predict the phase behavior as a continuous (Eulerian) medium, and is applicable for arbitrary Knudsen number and arbitrary Stokes number . Source terms for collision models such as Bhatnagar-Gross-Krook (BGK) and models for evaporation, coalescence, breakage, and aggregation are also available. By retaining a quadrature approximation of a probability density function (PDF), a set of abscissas and weights retain the physical solution and allow for the construction of moments that generate a set of partial differential equations (PDE's). QBMM has shown promising preliminary results for modeling granular gases or dispersed phases within carrier fluids and offers an alternative to Lagrangian methods such as Discrete Particle Simulation (DPS). The Lattice Boltzmann Method (LBM) shares some strong similarities in concept, but it relies on fixed abscissas whereas quadrature-based methods are more adaptive. Additionally, the Navier–Stokes equations(N-S) can be derived from the moment method approach.
Method
QBMM is a relatively new simulation technique for granular systems and has attracted interest from researchers in computational physics, chemistry, and engineering. QBMM is similar to traditional CFD methods, which solve the conservation equations of macroscopic properties (i.e., mass, momentum, and energy) numerically, but QBMM accomplishes this by modeling the fluid as consisting of fictive particles, or nodes, that constitute a discretized PDF. A node consists of an abscissa/weight pair and the weight defines the probability of finding a particle that has the value of its abscissa. This quadrature approximation may also be adaptive, meaning that the number of nodes can increase/decrease to accommodate appropriately complex/simple PDF's. Due to its statistical nature, QBMM has several advantages over other conventional Lagrangian methods, especially in dealing with complex boundaries, incorporating microscopic interactions (such as collisions), parallelization of the algorithm, and computational costs being largely independent of particle population. The numerical methods for solving the system of partial differential equations can be interpreted as the propagation (with a flux term) and interactions (source terms) of fictitious particle probabilities in an Eulerian framework.
Implementations
QBMM is a family of methods encompassing a variety of models, some of which are designed specifically to handle PDF's of passive variables, and others more complex, capable of multidimensional PDF's of active variables (such as velocity). Note that the full representation of the PDF is , where the parameters and represent the external coordinates of time and space respectively, while the internal coordinate vector, , may contain any additional desired degrees of freedom to represent the particles, e.g., temperature , diameter , velocity , angular velocity, etc.
The applicability of these methods depends upon which particle parameters are important (velocity, diameter, temperature, etc.), and importantly upon two values of the phase: and . For example, a monokinetic fluid will have a single velocity vector at each point in space, ; therefore, its corresponding PDF, , is a Dirac Delta function at every point in space. Similarly, a monodisperse phase has a constant diameter for all particles so that is also a Delta function at every point in space. In those cases a PDF is superfluous and can instead be modeled by just tracking a single value corresponding to the abscissa of the Delta function, and the Navier-Stokes equations may be far more optimal to implement.
QMOM
One of the earliest applications of QBMM was the Quadrature Method of Moments (QMOM) by McGraw in 1997. This method was used mainly for aerosol sprays and droplets by tracking their diameters through phenomenon such as breakage, coalescence, evaporation, etc.
DQMOM
Direct QMOM (DQMOM) is a mathematical simplification of QMOM that works best for dispersed phases with low Stokes numbers. DQMOM is a very efficient model because the weights and abscissas appear directly in the transport equations alleviating any need for moment construction and inversion. When dealing with low inertia particles where tracking few passive variables is of concern, DQMOM is very advantageous; however, because a large set of unknowns (abscissas and weights) is solved simultaneously, the matrix inversions cannot guaranteed realizable results in some circumstances, even with expensive iterative processes.
CQMOM
In 2011 the Conditional QMOM (CQMOM) method was published by Yuan and Fox and this comprehensive method is applicable to modeling very general problems by tracking moments of the PDF, , with an arbitrary number of internal parameters. This requires a moment construction and inversion process that converts the set of moments into nodes, and vice versa. The inversion process is the main source of computational costs, but overall CQMOM offers realizable results that DQMOM cannot guarantee.
Polykinetic
CQMOM has the ability to model a fully 3D velocity PDF, known as a polykinetic approach where is not assumed to be a single Delta function. The method is computationally expensive, but very cost-effective when collisions are considered or in dense particle regimes, , which cannot be modeled using N-S and where DPS is computationally restrictive. CQMOM is also applicable for a dispersed phase where .
The specialized Boltzmann Equation for is
where is the acceleration source term (drag, gravity, etc.) and is the collision source term. The velocity moment of in 3D space is defined as
where is the velocity in the d'th dimension, are the multiplicities (arbitrary integer exponents) used to "weight" the PDF integration, and is the order of the moment . Similarly, by taking moments of the entire Boltzmann equation, any number of arbitrary integro-differential equations may be generated,
where is a vector of the arbitrary integer indices and is the element-wise scalar multiplication of the vectors. The convective term includes moments of order and requires closure. Moment closure is achieved using the quadrature approximation of the moments,
where are the velocity abscissas, the weight for the 'th node, and the total number of nodes in the quadrature approximation.
EQMOM
Extended QMOM (EQMOM) gives the quadrature representation of the PDF more flexibility. Instead of relying solely on Dirac delta functions as the basis functions, it uses a Gaussian distribution, thus allowing more complex PDF's to be represented with fewer quadrature nodes.
Limitations
Despite the increasing popularity of QBMM in solving the kinetic equations of granular gases, this novel approach has some limitations. At present, CQMOM's computational costs are significantly higher than that of the N-S Equations when or the DPS costs when or . Additionally, the finite-volume flux methods introduce errors that can lead to instabilities in the moment-inversion process. Nevertheless, the wide applications of this method show its potential in computational physics, including microfluidics. QBMM demonstrates promising results in the area of high Knudsen number and high Stokes number flows.
Further reading
Notes
External links
: ECQMOM presentation
: QMOM presentation
Computational fluid dynamics | Quadrature based moment methods | [
"Physics",
"Chemistry"
] | 1,602 | [
"Computational fluid dynamics",
"Fluid dynamics",
"Computational physics"
] |
67,319,144 | https://en.wikipedia.org/wiki/William%20Edward%20Gibbs | William Edward Gibbs (1890 – 18 January 1934) was the second Ramsay Memorial Professor of Chemical Engineering at University College London. He was the second head of the department replacing the first, E. C. Williams.
Career
Gibbs completed his graduation at the University of Liverpool taking his first post with the Straits Trading Company in Singapore as an Assistant Chemist. He returned to the University of Liverpool as a lecturer in Metallurgy, where he researched the issue of the recovery of tin from the waste material by using electro chemical recovery. He was also made an investigator with the Corrosion Committee at the Institute of Metals.
During the First World War, Gibbs held the post of chief examiner of the Aeronautical Inspection Department, before becoming the chief chemist at the Royal Navy's rolling mill at Weston, Southampton. At the end of the war, he was appointed the chief chemist at the Salt Union, where he gained great experience in the methods and problems of evaporation and crystallisation.
In 1924, Gibbs gave the general name aerosol to the dispers systems in air. See in this context Clouds and Smokes, page 8.
In 1928, Gibbs was appointed as the successor to E. C. Williams, as Ramsay professor for chemical engineering at University College, London. Due to his predecessor's fund raising activities with British chemical companies, the university was planning a large expansion of the department, which Gibbs designed and carried out, concluding with the opening of the new Ramsey Laboratory in 1932. In 1930, Gibbs was an expert witness in the case of United Lamp Black Works vs. Greenwich Borough Council.
Death
In January 1934, Gibbs died suddenly at the age of 44. He was replaced as the Ramsay professor by H. E. Watson.
Publications
Gibbs, William E. (1924): Clouds and Smokes. The properties of disperse systems in gases and their practical applications.
References
British chemical engineers
1890 births
1934 deaths
Alumni of the University of Liverpool
Chemical engineering academics
Academics of University College London | William Edward Gibbs | [
"Chemistry"
] | 397 | [
"Chemical engineering academics",
"Chemical engineers"
] |
67,319,458 | https://en.wikipedia.org/wiki/A.%20W.%20Faber%20Model%20366 | The A. W. Faber Model 366 was an unusual model of slide rule, manufactured in Germany by the A. W. Faber Company around 1909, with scales that followed a system invented by Johannes Schumacher (1858-1930) that used discrete logarithms to calculate products of integers without approximation.
The Model 366 is notable for its table of numbers, mapping the numbers 1 to 100 to a permutation of the numbers 0 to 99 in a pattern based on discrete logarithms. The markings on the table are:
{| style="text-align: right; font-size: 90%;"
| N || || 0 || 1 || 2 || 3 || 4 || 5 || 6 || 7 || 8 || 9
|-
|
|-
| || || || 0 || 1 || 69 || 2 || 24 || 70 || 9 || 3 || 38
|-
| 1 || || 25 || 13 || 71 || 66 || 10 || 93 || 4 || 30 || 39 || 96
|-
| 2 || || 26 || 78 || 14 || 86 || 72 || 48 || 67 || 7 || 11 || 91
|-
| 3 || || 94 || 84 || 5 || 82 || 31 || 33 || 40 || 56 || 97 || 35
|-
| 4 || || 27 || 45 || 79 || 42 || 15 || 62 || 87 || 58 || 73 || 18
|-
| 5 || || 49 || 99 || 68 || 23 || 8 || 37 || 12 || 65 || 92 || 29
|-
| 6 || || 95 || 77 || 85 || 47 || 6 || 90 || 83 || 81 || 32 || 55
|-
| 7 || || 34 || 44 || 41 || 61 || 57 || 17 || 98 || 22 || 36 || 64
|-
| 8 || || 28 || 76 || 46 || 89 || 80 || 54 || 43 || 60 || 16 || 21
|-
| 9 || || 63 || 75 || 88 || 53 || 59 || 20 || 74 || 52 || 19 || 51
|-
| 10 || || 50
|}
The slide rule has two scales on each side of the upper edge of the slider marked with the integers 1 to 100 in a different permuted order, evenly spaced apart. The ordering of the numbers on these scales is
1, 2, 4, 8, 16, 32, 64, 27, 54, 7, 14, 28, 56, 11, 22, 44, 88, 75, 49, 98, 95, 89, 77, 53, 5, 10, 20, 40, 80, 59, 17, 34, 68, 35, 70, 39, 78, 55, 9, 18, 36, 72, 43, 86, 71, 41, 82, 63, 25, 50, 100, 99, 97, 93, 85, 69, 37, 74, 47, 94, 87, 73, 45, 90, 79, 57, 13, 26, 52, 3, 6, 12, 24, 48, 96, 91, 81, 61, 21, 42, 84, 67, 33, 66, 31, 62, 23, 46, 92, 83, 65, 29, 58, 15, 30, 60, 19, 38, 76, 51
which corresponds to the inverse permutation to the one given by the number table.
There are also two scales on each side of the lower edge of the slider, consisting of the integers 0 to 100 similarly spaced, but in ascending order, with the zero on the lower scales lining up with the 1 on the upper scales.
Schumacher's indices are an example of Jacobi indices, generated with p = 101 and g = 2. Schumacher's system of indices correctly generates the desired products, but is not unique: several other similar systems have been created by others, including systems by Ludgate, Remak and Korn.
An elaborate system of rules had to be used to compute products of numbers larger than 101.
Very few of the Model 366 slide rules remain, with only five known to have survived.
See also
Irish logarithms, a similar scheme intended for use in a mechanical calculation machine, introduced in 1909 by Percy Ludgate
Canon arithmeticus, a table of indices and powers with respect to primitive roots originally published by Carl Gustav Jacob Jacobi
References
External links
Ein Rechenschieber mit Teilung in gleiche Intervalle auf der Grundlage der zahlentheoretischen Indizes. Für den Unterricht konstruiert (English: "A slide rule with division into equal intervals based on number theoretic indices. Designed for teaching."), Dr. Joh. Schumacher, Munich, 1909 (in German)
Rechnerlexikon article on discrete logarithms, including use in the Schumacher slide rule (in German)
High resolution images of the Model 366 slide rule at the Oughtred Society
A Model 366 slide rule made in 1921
Close-up of the number table attached to the cursor
Mechanical calculators
Discrete mathematics
Multiplication | A. W. Faber Model 366 | [
"Mathematics"
] | 1,151 | [
"Discrete mathematics"
] |
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