25,127 research outputs found
Introductory workshops on remote sensing as related to geological problems in Georgia
There are no author-identified significant results in this report
Observation of a possible superflare on Proxima Centauri
We report the observation on UT 2017 July 1 of an unusually powerful flare detected in near-infrared continuum photometry of Proxima Centauri. During a campaign monitoring the star for possible exoplanet transits, we identified an increase in Sloan i' flux leading to an observed peak at BJD 2457935.996 that was at least 10 per cent over pre-flare flux in this band. It was followed by a two-component rapid decline in the first 100 s that became a slower exponential decay with time constant of 1350 s. A smaller flare event 1300 s after the first added an incremental peak flux increase of 1 per cent of pre-flare flux. Since the onset of the flare was not fully time resolved at a cadence of 62 s, its actual peak value is unknown but greater than the time average over a single exposure of 20 s. The i' band is representative of broad optical and near-IR continuum flux over which the integrated energy of the flare is 100 times the stellar luminosity. This meets the criteria that established the concept of superflares on similar stars. The resulting implied ultraviolet flux and space weather could have had an extreme effect on the atmospheres of planets within the star's otherwise habitable zone
SYSTEMS ANALYSIS OF LIVESTOCK WASTE MANAGEMENT: A STUDY OF LARGE-SCALE DAIRYING
The analytical approach to studying waste management is investigated here in the context of large scale dairying. The typical short-run approach that regards waste management as separable from primary production is contrasted with a longer-run systems approach in which waste management is regarded as an interdependent stage of production. Failure to consider interdependencies between waste management and agricultural production could compromise potential efficiencies in the overall system. Furthermore, cooperative waste treatment and disposal among livestock producers may contribute to greater efficiency and afford opportunities for resource conservation and recovery through waste utilization.Environmental Economics and Policy, Livestock Production/Industries,
Analysis of β-globin chromatin micro-environment using a novel 3C variant, 4Cv
Copyright: © 2010 Pink et al.Higher order chromatin folding is critical to a number of developmental processes, including the regulation of gene expression. Recently developed biochemical techniques such as RNA TRAP and chromosome conformation capture (3C) have provided us with the tools to probe chromosomal structures. These techniques have been applied to the β-globin locus, revealing a complex pattern of interactions with regions along the chromosome that the gene resides on. However, biochemical and microscopy data on the nature of β-globin interactions with other chromosomes is contradictory. Therefore we developed a novel 4C variant, Complete-genome 3C by vectorette amplification (4Cv), which allows an unbiased and quantitative method to examine chromosomal structure. We have used 4Cv to study the microenvironment of the β-globin locus in mice and show that a significant proportion of the interactions of β-globin are inter-chromosomal. Furthermore, our data show that in the liver, where the gene is active, β-globin is more likely to interact with other chromosomes, compared to the brain where the gene is silent and is more likely to interact with other regions along the same chromosome. Our data suggest that transcriptional activation of the β-globin locus leads to a change in nuclear position relative to the chromosome territory.Ryan Pink is supported by a grant from Action Medical Research; Daniel Caley is supported by a grant from The Dunhill Medical Trust; David Carter is supported by a grant from the British Society for Haematology
A Puzzling Merger in A3266: the Hydrodynamic Picture from XMM-Newton
Using the mosaic of nine XMM-Newton observations, we study the hydrodynamic
state of the merging cluster of galaxies Abell 3266. The high quality of the
spectroscopic data and large field of view of XMM-Netwon allow us to determine
the thermodynamic conditions of the intracluster medium on scales of order of
50 kpc. A high quality entropy map reveals the presence of an extended region
of low entropy gas, running from the primary cluster core toward the northeast
along the nominal merger axis. The mass of the low entropy gas amounts to
approximately 2e13 solar masses, which is comparable to the baryonic mass of
the core of a rich cluster. We test the possibility that the origin of the
observed low entropy gas is either related to the disruption a preexisting
cooling core in Abell 3266 or to the stripping of gas from an infalling
subcluster companion. We find that both the radial pressure and entropy
profiles as well as the iron abundance of Abell 3266 do not resemble those in
other known cooling core clusters (Abell 478). Thus we conclude that the low
entropy region is subcluster gas in the process of being stripped off from its
dark matter halo. In this scenario the subcluster would be falling onto the
core of A3266 from the foreground. This would also help interpret the observed
high velocity dispersion of the galaxies in the cluster center, provided that
the mass of the subcluster is at most a tenth of the mass of the main cluster.Comment: 6 pages, ApJ sub
Fractal universe and quantum gravity
We propose a field theory which lives in fractal spacetime and is argued to
be Lorentz invariant, power-counting renormalizable, ultraviolet finite, and
causal. The system flows from an ultraviolet fixed point, where spacetime has
Hausdorff dimension 2, to an infrared limit coinciding with a standard
four-dimensional field theory. Classically, the fractal world where fields live
exchanges energy momentum with the bulk with integer topological dimension.
However, the total energy momentum is conserved. We consider the dynamics and
the propagator of a scalar field. Implications for quantum gravity, cosmology,
and the cosmological constant are discussed.Comment: 4 pages. v2: typos corrected; v3: discussion improved, intuitive
introduction added, matches the published versio
Magnetic properties and spin dynamics in single molecule paramagnets Cu6Fe and Cu6Co
The magnetic properties and the spin dynamics of two molecular magnets have
been investigated by magnetization and d.c. susceptibility measurements,
Electron Paramagnetic Resonance (EPR) and proton Nuclear Magnetic Resonance
(NMR) over a wide range of temperature (1.6-300K) at applied magnetic fields,
H=0.5 and 1.5 Tesla. The two molecular magnets consist of
CuII(saldmen)(H2O)}6{FeIII(CN)6}](ClO4)38H2O in short Cu6Fe and the analog
compound with cobalt, Cu6Co. It is found that in Cu6Fe whose magnetic core is
constituted by six Cu2+ ions and one Fe3+ ion all with s=1/2, a weak
ferromagnetic interaction between Cu2+ moments through the central Fe3+ ion
with J = 0.14 K is present, while in Cu6Co the Co3+ ion is diamagnetic and the
weak interaction is antiferromagnetic with J = -1.12 K. The NMR spectra show
the presence of non equivalent groups of protons with a measurable contact
hyperfine interaction consistent with a small admixture of s-wave function with
the d-function of the magnetic ion. The NMR relaxation results are explained in
terms of a single ion (Cu2+, Fe3+, Co3+) uncorrelated spin dynamics with an
almost temperature independent correlation time due to the weak magnetic
exchange interaction. We conclude that the two molecular magnets studied here
behave as single molecule paramagnets with a very weak intramolecular
interaction, almost of the order of the dipolar intermolecular interaction.
Thus they represent a new class of molecular magnets which differ from the
single molecule magnets investigated up to now, where the intramolecular
interaction is much larger than the intermolecular one
Modeling and Analysis of Power Processing Systems (MAPPS). Volume 2: Appendices
The computer programs and derivations generated in support of the modeling and design optimization program are presented. Programs for the buck regulator, boost regulator, and buck-boost regulator are described. The computer program for the design optimization calculations is presented. Constraints for the boost and buck-boost converter were derived. Derivations of state-space equations and transfer functions are presented. Computer lists for the converters are presented, and the input parameters justified
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