9,017 research outputs found
Carbon isotopes in bulk carbonaceous chondrites
The chemical and physical processes involved in the formation of the solar system are examined. Primitive matter has been found on a microscopic scale in a variety of meteorites: fragments of small solar system bodies that were never part of a large planet. This primitive matter has, in most cases, been identified by the presence of anomalous abundances of some isotopes of the chemical elements. Of particular interest for carbon isotope studies are the primitive meteorites known as carbonaceous chondrites. Using a selective oxidation technique to sort out the carbon contained in different chemical forms (graphite, carbonates, and organic matter), four carbonaceous chondrites are analyzed. The presence of the (13) C-rich component was confirmed and additional carbon components with different, but characteristic, isotopic signatures were resolved
Is the iPhone an accurate and useful tool for the monitoring of spinal deformity?
The progression of spinal deformity is traditionally monitored by spinal surgeons using the Cobb method on hardcopy radiographs with a protractor and pencil. The rotation of the spine and ribcage (rib hump) in scoliosis is measured with a simple hand-held inclinometer (Scoliometer). The iPhone and other smart phones have the capability to accurately sense inclination, and can therefore be used to measure Cobb angles and rib hump angulation. The purpose of this study was to quantify the performance of the iPhone compared to a standard protractor for measuring Cobb angles and the Scoliometer for measuring rib humps. The study concluded that the iPhone is a clinically equivalent measuring tool to the traditional protractor and Scoliomete
Resolving Conflict on Campus: A Case Study on Free Speech and Controversial Speakers
By their very charge, institutions of higher education are intended to serve as venues for exploring personal ideologies, promoting intellectual curiosity, and en-couraging vigorous debate about contested issues. However, when an institution and its core values come into direct conflict with viewpoints that are fundamentally inconsistent with those values, the dissonance created by the clash of perspectives can be profound. Fundamental differences in perspective on highly charged issues and topics have become recurring themes for universities in the United States. From campus speakers, to speaker protests, to demonstrations in support of free speech and a range of other inclusion and diversity-related topics, the work of managing diversity related to conflict has become a high priority issue for campuses nation-wide
Spin-1 Particles with Light-Front Approach
For the vector sector, i.e, mesons with spin-1, the electromagnetic form
factors and anothers observables are calculated with the light-front approach.
However, the light-front quantum field theory have some problems, for example,
the rotational symmetry breaking. We solve that problem added the zero modes
contribuition to the matrix elements of the electromagnetic current, besides
the valence contribuition. We found that among the four independent matrix
elements of the plus component in the light-front helicity basis only the one carries zero mode contributions.Comment: 5 pages. 3 Figures, use latex and EPJ styl
The Fabry disease-associated lipid Lyso-Gb3 enhances voltage-gated calcium currents in sensory neurons and causes pain
Fabry disease is an X-linked lysosomal storage disorder characterised by accumulation of glycosphingolipids, and accompanied by clinical manifestations, such as cardiac disorders, renal failure, pain and peripheral neuropathy. Globotriaosylsphingosine (lyso-Gb3), a deacylated form of globotriaosylceramide (Gb3), has emerged as a marker of Fabry disease. We investigated the link between Gb3, lyso-Gb3 and pain. Plantar administration of lyso-Gb3 or Gb3 caused mechanical allodynia in healthy mice. In vitro application of 100nM lyso-Gb3 caused uptake of extracellular calcium in 10% of sensory neurons expressing nociceptor markers, rising to 40% of neurons at 1μM, a concentration that may occur in Fabry disease patients. Peak current densities of voltage-dependent Ca(2+) channels were substantially enhanced by application of 1μM lyso-Gb3. These studies suggest a direct role for lyso-Gb3 in the sensitisation of peripheral nociceptive neurons that may provide an opportunity for therapeutic intervention in the treatment of Fabry disease-associated pain
Homothetic Wyman Spacetimes
The time-dependent, spherically symmetric, Wyman sector of the Unified Field
Theory is shown to be equivalent to a self-gravitating scalar field with a
positive-definite, repulsive self-interaction potential. A homothetic symmetry
is imposed on the fundamental tensor, and the resulting autonomous system is
numerically integrated. Near the critical point (between the collapsing and
non-collapsing spacetimes) the system displays an approximately periodic
alternation between collapsing and dispersive epochs.Comment: 15 pages with 6 figures; requires amsart, amssymb, amsmath, graphicx;
formatted for publication in Int. J. Mod. Phys.
Mission description and in-flight operations of ERBE instruments on ERBS, NOAA 9, and NOAA 10 spacecraft
Instruments of the Earth Radiation Budget Experiment (ERBE) are operating on three different Earth-orbiting spacecraft. The Earth Radiation Budget Satellite (ERBS) is operated by NASA, and NOAA 9 and NOAA 10 weather satellites are operated by the National Oceanic and Atmospheric Administration (NOAA). This paper is the second in a series that describes the ERBE mission, and data processing and validation procedures. This paper describes the spacecraft and instrument operations for the second full year of in-orbit operations, which extend from February 1986 through January 1987. Validation and archival of radiation measurements made by ERBE instruments during this second year of operation were completed in July 1991. This period includes the only time, November 1986 through January 1987, during which all ERBE instruments aboard the ERBE, NOAA 9, and NOAA 10 spacecraft were simultaneously operational. This paper covers normal and special operations of the spacecraft and instruments, operational anomalies, and the responses of the instruments to in-orbit and seasonal variations in the solar environment
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