7,410 research outputs found
Laser-heated rocket studies
CW laser heated rocket propulsion was investigated in both the flowing core and stationary core configurations. The laser radiation considered was 10.6 micrometers, and the working gas was unseeded hydrogen. The areas investigated included initiation of a hydrogen plasma capable of absorbing laser radiation, the radiation emission properties of hot, ionized hydrogen, the flow of hot hydrogen while absorbing and radiating, the heat losses from the gas and the rocket performance. The stationary core configuration was investigated qualitatively and semi-quantitatively. It was found that the flowing core rockets can have specific impulses between 1,500 and 3,300 sec. They are small devices, whose heating zone is only a millimeter to a few centimeters long, and millimeters to centimeters in radius, for laser power levels varying from 10 to 5,000 kW, and pressure levels of 3 to 10 atm. Heat protection of the walls is a vital necessity, though the fraction of laser power lost to the walls can be as low as 10% for larger powers, making the rockets thermally efficient
Law's Looking Glass: Expert Identification Evidence Derived from Photographic and Video Images
This article offers a critical overview of expert identification evidence based on images. It reviews the Australian case law and then, in an interdisciplinary manner, endeavours to explain methodological, technical and theoretical problems with facial mapping evidence. It suggests that extant admissibility jurisprudence and traditional safeguards associated with expert opinion evidence and the adversarial trial might not adequately protect those accused of committing criminal acts when they are confronted with incriminating expert identification evidence
Trace multi-element analysis of biological tissue by protoninduced X-ray fluorescence spectroscopy
1RXS J232953.9+062814: A Dwarf Nova with a 64-minute Orbital Period and a Conspicuous Secondary Star
We present spectroscopy and time-series photometry of the newly discovered
dwarf nova 1RXS J232953.9+062814. Photometry in superoutburst reveals a
superhump with a period of 66.06(6) minutes. The low state spectrum shows
Balmer and HeI emission on a blue continuum, and in addition shows a rich
absorption spectrum of type K4 +- 2. The absorption velocity is modulated
sinusoidally at P_orb = 64.176(5) min, with semi-amplitude K = 348(4) km/s. The
low-state light curve is double-humped at this period, and phased as expected
for ellipsoidal variations. The absorption strength does not vary appreciably
around the orbit. The orbital period is shorter than any other cataclysmic
variable save for a handful of helium-star systems and V485 Centauri (59
minutes). The secondary is much hotter than main sequence stars of similar
mass, but is well-matched by helium-enriched models, indicating that the
secondary evolved from a more massive progenitor. A preliminary calculation in
which a 1.2 solar-mass star begins mass transfer near the end of H burning
matches this system's characteristics remarkably well.Comment: accepted to Astrophysical Journal Letters; 14 pages, 3 eps figures +
1 jpg greyscale figur
Reconstruction of metabolic networks from high-throughput metabolite profiling data: in silico analysis of red blood cell metabolism
We investigate the ability of algorithms developed for reverse engineering of
transcriptional regulatory networks to reconstruct metabolic networks from
high-throughput metabolite profiling data. For this, we generate synthetic
metabolic profiles for benchmarking purposes based on a well-established model
for red blood cell metabolism. A variety of data sets is generated, accounting
for different properties of real metabolic networks, such as experimental
noise, metabolite correlations, and temporal dynamics. These data sets are made
available online. We apply ARACNE, a mainstream transcriptional networks
reverse engineering algorithm, to these data sets and observe performance
comparable to that obtained in the transcriptional domain, for which the
algorithm was originally designed.Comment: 14 pages, 3 figures. Presented at the DIMACS Workshop on Dialogue on
Reverse Engineering Assessment and Methods (DREAM), Sep 200
High levels of brain-type creatine kinase activity in human platelets and leukocytes: a genetic anomaly with autosomal dominant inheritance
The ectopic expression in peripheral blood cells of the brain-type creatine kinase (CKB) is an autosomal dominant inherited anomaly named CKBE (MIM ID 123270). Here, we characterized the CK activity in serum, platelets (PLT) and leukocytes (WBC) of 22 probands (from 8 unrelated families) and 10 controls. CK activity was measured by standard UV-photometry. Expression of the CKB gene was analyzed by real-time PCR and Western blotting. DNA sequencing including bisulfite treatment was used for molecular analysis of the CKB gene. Serum CK levels were comparable between probands and controls. CKBE probands revealed significantly higher CK activity in PLT (3.7 +/- 2.7 versus 179.2 +/- 83.0 U/10(12) PLT; p<0.001) and WBC (0.4 +/- 0.3 versus 2.6 +/- 2.1 U/10(9) WBC; p=0.004). Inhibitory anti-CKM antibodies did not affect CK activity indicating that the CK activity is generated exclusively by the CK-BB isoenzyme. CKB mRNA and protein levels were significantly higher in PLT and WBC from probands compared to controls. Re-sequencing of the entire CKB gene and methylation analysis of a CpG island revealed no alteration in CKBE probands. The genetic basis of CKBE remains unclear, however, we propose that a de-methylated CKB gene is inherited that leads to high CKB expression levels in myeloic precursor cells in the bone marrow
Physics Analysis Expert PAX: First Applications
PAX (Physics Analysis Expert) is a novel, C++ based toolkit designed to
assist teams in particle physics data analysis issues. The core of PAX are
event interpretation containers, holding relevant information about and
possible interpretations of a physics event. Providing this new level of
abstraction beyond the results of the detector reconstruction programs, PAX
facilitates the buildup and use of modern analysis factories. Class structure
and user command syntax of PAX are set up to support expert teams as well as
newcomers in preparing for the challenges expected to arise in the data
analysis at future hadron colliders.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, LaTeX, 10 eps figures. PSN
THLT00
Energy-efficiency evaluation of computation offloading in personal computing
Cloud computing has become common practice for a wide variety of user communities. Yet, the energy efficiency and end-to-end performance benefits of cloud computing are not fully understood. Here, we focus specifically on the trade-off between local power saving and increased execution time when work is offloaded from a user’s PC to a cloud environment. We have set up a 14-node private cloud and have executed a variety of applications with different processing demands. We have measured the energy cost at the level of the individual user’s PC, at the level of the cloud, as well as at the two combined, contrasted to the execution time for each application when running on the PC and when running on the cloud. Our results indicate that the tradeoff between energy cost and performance differs considerably between applications of different types. In most cases investigated, the total increase in energy consumption, incurred by running that additional application, was reduced significantly. This shows that research on using cloud computing as a means to reduce the overall carbon footprint of IT is warranted. Of course, the energy gains were more pronounced for energy-selfish users, who are only interested in reducing their own carbon footprint, but these savings came at the expense of performance, with execution time increase ranging from 1% to 84% for different applications
Modelling the Long-Term Impact on Herder Incomes and Environmental Services in an Uncertain World
Environmental, market and political influences affect herders’ livelihoods with the expectation that they maintain biologically and economically resilient systems. To balance these external influences and the trade-offs within a grassland system it involves the consideration of interactions between grassland ecology, technology use, environmental externalities, utilisation by grazing animals for food and fibre production, and the long-term profitability of the farming system. Many of these variables are slow-moving and are trade-offs are most efficiently studied with models. The StageTHREE Sustainable Grasslands Model, which utilizes the core functions and dynamics of more mechanistic tools, has been designed to minimize the skill and data required for parameterisation. It allows the key dynamics of the grassland systems to be incorporated along with the stochasticity of the system, in terms of both the uncertainty of the production and market environment. This enables an investigation into the sustainability and environmental impacts of alternative livestock management practices, so that these can be evaluated in relation to policy options. This paper presents an insight into the integration of herder level bioeconomic modelling for the analysis of grassland policy impacts in Mongolia and China. The research highlights that policy settings that reduce stocking rates can improve the environmental services from grasslands, and in most cases, also improve herder livelihoods and resilience
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