1,869 research outputs found
Low-cost, aerial photographic inventory of tidal wetlands
There are no author-identified significant results in this report
High-pressure x-ray diffraction study of bulk and nanocrystalline PbMoO4
We studied the effects of high-pressure on the crystalline structure of bulk
and nanocrystalline scheelite-type PbMoO4. We found that in both cases the
compressibility of the materials is highly non-isotropic, being the c-axis the
most compressible one. We also observed that the volume compressibility of
nanocrystals becomes higher that the bulk one at 5 GPa. In addition, at 10.7(8)
GPa we observed the onset of an structural phase transition in bulk PbMoO4. The
high-pressure phase has a monoclinic structure similar to M-fergusonite. The
transition is reversible and not volume change is detected between the low- and
high-pressure phases. No additional structural changes or evidence of
decomposition are found up to 21.1 GPa. In contrast nanocrystalline PbMoO4
remains in the scheelite structure at least up to 16.1 GPa. Finally, the
equation of state for bulk and nanocrystalline PbMoO4 are also determined.Comment: 18 pages, 4 figure
Postmortem tissue distribution of morphine and its metabolites in a series of heroin related deaths
The abuse of heroin (diamorphine) and heroin deaths are growing around the world. The interpretation of the toxicological results from suspected heroin deaths is notoriously difficult especially in cases where there may be limited samples. In order to help forensic practitioners with heroin interpretation we determined the concentration of morphine (M), morphine‐3‐glucuronide (M3G) and morphine‐6‐glucuronide (M6G) in blood (femoral and cardiac), brain (thalamus), liver (deep right lobe), bone marrow (sternum), skeletal muscle (psoas) and vitreous humor in 44 heroin related deaths. The presence of 6‐monoacetylmorphine (6‐MAM) in any of the postmortem samples was used as confirmation of heroin use. Quantitation was carried out using a validated LC‐MS/MS method with solid phase extraction. We also determined the presence of papaverine, noscapine and codeine in the samples, substances often found in illicit heroin and that may help determine illicit heroin use. The results of this study show that vitreous is the best sample to detect 6‐MAM (100% of cases), and thus heroin use. The results of the M, M3G and M6G quantitation in this study allow a degree of interpretation when samples are limited. However in some cases it may not be possible to determine heroin/morphine use as in 4 cases in muscle (3 cases in bone marrow) no morphine, morphine‐3‐glucuronide or morphine‐6‐glucuronide was detected, even though they were detected in other case samples. As always postmortem cases of suspected morphine/heroin intoxication should be interpreted with care and with as much case knowledge as possible
Evolving the Technical Infrastructure of the Planetary Data System for the 21st Century
The Planetary Data System (PDS) was established in 1989 as a distributed system to assure scientific oversight. Initially the PDS followed guidelines recommended by the National Academies Committee on Data Management and Computation (CODMAC, 1982) and placed emphasis on archiving validated datasets. But overtime user demands, supported by increased computing capabilities and communication methods, have placed increasing demands on the PDS. The PDS must add additional services to better enable scientific analysis within distributed environments and to ensure that those services integrate with existing systems and data. To face these challenges the Planetary Data System (PDS) must modernize its architecture and technical implementation. The PDS 2010 project addresses these challenges. As part of this project, the PDS has three fundamental project goals that include: (1) Providing more efficient client delivery of data by data providers to the PDS (2) Enabling a stable, long-term usable planetary science data archive (3) Enabling services for the data consumer to find, access and use the data they require in contemporary data formats. In order to achieve these goals, the PDS 2010 project is upgrading both the technical infrastructure and the data standards to support increased efficiency in data delivery as well as usability of the PDS. Efforts are underway to interface with missions as early as possible and to streamline the preparation and delivery of data to the PDS. Likewise, the PDS is working to define and plan for data services that will help researchers to perform analysis in cost-constrained environments. This presentation will cover the PDS 2010 project including the goals, data standards and technical implementation plans that are underway within the Planetary Data System. It will discuss the plans for moving from the current system, version PDS 3, to version PDS 4
PDS4: Developing the Next Generation Planetary Data System
The Planetary Data System (PDS) is in the midst of a major upgrade to its system. This upgrade is a critical modernization of the PDS as it prepares to support the future needs of both the mission and scientific community. It entails improvements to the software system and the data standards, capitalizing on newer, data system approaches. The upgrade is important not only for the purpose of capturing results from NASA planetary science missions, but also for improving standards and interoperability among international planetary science data archives. As the demands of the missions and science community increase, PDS is positioning itself to evolve and meet those demands
From stars to patients: Lessons from space science and astrophysics for health care informatics
Big Data are revolutionizing nearly every aspect of the modern society. One area where this can have a profound positive societal impact is the field of Health Care Informatics (HCI), which faces many challenges. The key idea behind this study is: can we use some of the experience and technical and methodological solutions from the fields that have successfully adapted to the Big Data era, namely astronomy and space science, to help accelerate the progress of HCI? We illustrate this with examples from the Virtual Observatory framework, and the NCI EDRN project. An effective sharing and reuse of tools, methods, and experiences from different fields can save a lot of effort, time, and expense. HCI can thus benefit from the proven solutions to big data challenges from other domains
Trace formulae for non-equilibrium Casimir interactions, heat radiation and heat transfer for arbitrary objects
We present a detailed derivation of heat radiation, heat transfer and
(Casimir) interactions for N arbitrary objects in the framework of
fluctuational electrodynamics in thermal non-equilibrium. The results can be
expressed as basis-independent trace formulae in terms of the scattering
operators of the individual objects. We prove that heat radiation of a single
object is positive, and that heat transfer (for two arbitrary passive objects)
is from the hotter to a colder body. The heat transferred is also symmetric,
exactly reversed if the two temperatures are exchanged. Introducing partial
wave-expansions, we transform the results for radiation, transfer and forces
into traces of matrices that can be evaluated in any basis, analogous to the
equilibrium Casimir force. The method is illustrated by (re)deriving the heat
radiation of a plate, a sphere and a cylinder. We analyze the radiation of a
sphere for different materials, emphasizing that a simplification often
employed for metallic nano-spheres is typically invalid. We derive asymptotic
formulae for heat transfer and non-equilibrium interactions for the cases of a
sphere in front a plate and for two spheres, extending previous results. As an
example, we show that a hot nano-sphere can levitate above a plate with the
repulsive non-equilibrium force overcoming gravity -- an effect that is not due
to radiation pressure.Comment: 29 pages, 6 figures (v2: Sentence added in Sec. 1
Optical measurement of torque exerted on an elongated object by a non-circular laser beam
We have developed a scheme to measure the optical torque, exerted by a laser
beam on a phase object, by measuring the orbital angular momentum of the
transmitted beam. The experiment is a macroscopic simulation of a situation in
optical tweezers, as orbital angular momentum has been widely used to apply
torque to microscopic objects. A hologram designed to generate LG02 modes and a
CCD camera are used to detect the orbital component of the beam. Experimental
results agree with theoretical numerical calculations, and the strength of the
orbital component suggest its usefulness in optical tweezers for
micromanipulation.Comment: 6 pages, 7 figures, v2: minor typographical correction
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