344 research outputs found
Large-Scale Spectroscopic Mapping of the Ophiuchi Molecular Cloud Complex I. The CH to NH Ratio as a Signpost of Cloud Characteristics
We present 2.5-square-degree CH N=1-0 and NH J=1-0 maps of the
Ophiuchi molecular cloud complex. These are the first large-scale maps
of the Ophiuchi molecular cloud complex with these two tracers. The
CH emission is spatially more extended than the NH emission. One
faint NH clump Oph-M and one CH ring Oph-RingSW are identified
for the first time. The observed CH to NH abundance ratio
([CH]/[NH]) varies between 5 and 110. We modeled the CH
and NH abundances with 1-D chemical models which show a clear decline
of [CH]/[NH] with chemical age. Such an evolutionary trend is
little affected by temperatures when they are below 40 K. At high density
(n 10 cm), however, the time it takes for the abundance
ratio to drop at least one order of magnitude becomes less than the dynamical
time (e.g., turbulence crossing time 10 years). The observed
[CH]/[NH] difference between L1688 and L1689 can be explained by
L1688 having chemically younger gas in relatively less dense regions. The
observed [CH]/[NH] values are the results of time evolution,
accelerated at higher densities. For the relative low density regions in L1688
where only CH emission was detected, the gas should be chemically younger.Comment: Accepted by ApJ, 45 pages, 10 figure
Signaling Network Assessment of Mutations and Copy Number Variations Predicts Breast Cancer Subtype-specific Drug Targets
Individual cancer cells carry a bewildering number of distinct genomic
alterations i.e., copy number variations and mutations, making it a challenge
to uncover genomic-driven mechanisms governing tumorigenesis. Here we performed
exome-sequencing on several breast cancer cell lines which represent two
subtypes, luminal and basal. We integrated this sequencing data, and functional
RNAi screening data (i.e., for identifying genes which are essential for cell
proliferation and survival), onto a human signaling network. Two
subtype-specific networks were identified, which potentially represent
core-signaling mechanisms underlying tumorigenesis. Within both networks, we
found that genes were differentially affected in different cell lines; i.e., in
some cell lines a gene was identified through RNAi screening whereas in others
it was genomically altered. Interestingly, we found that highly connected
network genes could be used to correctly classify breast tumors into subtypes
based on genomic alterations. Further, the networks effectively predicted
subtype-specific drug targets, which were experimentally validated.Comment: 4 figs, more related papers at http://www.cancer-systemsbiology.org,
appears in Cell Reports, 201
Magnetic field control of the near-field radiative heat transfer in three-body planar systems
Recently, the application of an external magnetic field to actively control
the near-field heat transfer has emerged as an appealing and promising
technique. Existing studies have shown that an external static magnetic field
tends to reduce the subwavelength radiative flux exchanged between two planar
structures containing magneto-optical (MO) materials, but so far the nearfield
thermomagnetic effects in systems with more such structures at different
temperatures have not been reported. Here, we are focused on examining how the
presence of an external magnetic field modifies the radiative energy transfer
in a many-body configuration consisting of three MO n-doped semiconductors
slabs, separated by subwavelength vacuum gaps. To exactly calculate the
radiative flux transferred in such an anisotropic planar system, a general
Green-function-based approach is offered, which allows one to investigate the
radiative heat transfer in arbitrary manybody systems with planar geometry. We
demonstrate that, under specific choices of the geometrical and thermal
parameters, the applied magnetic field is able to either reduce or enhance the
near-field energy transfer in three-element MO planar systems, depending on the
interplay between the damped evanescent fields of the zero-field surface waves
and the propagating hyperbolic modes induced by magnetic fields. Our study
broadens the understanding concerning to the use of external fields to actively
control the heat transfer in subwavelength regimes, and may be leveraged for
potential applications in the realm of nanoscale thermal management.Comment: 18 pages, 7 figure
Deep Supervised Hashing using Symmetric Relative Entropy
By virtue of their simplicity and efficiency, hashing algorithms have achieved significant success on large-scale approximate nearest neighbor search. Recently, many deep neural network based hashing methods have been proposed to improve the search accuracy by simultaneously learning both the feature representation and the binary hash functions. Most deep hashing methods depend on supervised semantic label information for preserving the distance or similarity between local structures, which unfortunately ignores the global distribution of the learned hash codes. We propose a novel deep supervised hashing method that aims to minimize the information loss generated during the embedding process. Specifically, the information loss is measured by the Jensen-Shannon divergence to ensure that compact hash codes have a similar distribution with those from the original images. Experimental results show that our method outperforms current state-of-the-art approaches on two benchmark datasets
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