21,098 research outputs found
Thermal effects in perturbative noncommutative gauge theories
The thermodynamics of gauge theories on the noncommutative plane is studied
in perturbation theory. For U(1) noncommutative Yang-Mills we compute the first
quantum correction to the ideal gas free energy density and study their
behavior in the low and high temperature regimes. Since the noncommutativity
scale effectively cutoff interactions at large distances, the theory is regular
in the infrared. In the case of U(N) noncommutative Yang-Mills we evaluate the
two-loop free energy density and find that it depends on the noncommutativity
parameter through the contribution of non-planar diagrams.Comment: 15 pages, harvmac. Minor changes with respect to v2. Footnote
expanded, remark added in Section 3, typos corrected and references added.
Final version to be published in JHE
Large-scale CFD simulations of the transitional and turbulent regime for the large human airways during rapid inhalation
Stanilov-Tsankov-Videv Theory
We survey some recent results concerning Stanilov-Tsankov-Videv theory,
conformal Osserman geometry, and Walker geometry which relate algebraic
properties of the curvature operator to the underlying geometry of the
manifold.Comment: This is a contribution to the Proceedings of the 2007 Midwest
Geometry Conference in honor of Thomas P. Branson, published in SIGMA
(Symmetry, Integrability and Geometry: Methods and Applications) at
http://www.emis.de/journals/SIGMA
A Knowledge Gradient Policy for Sequencing Experiments to Identify the Structure of RNA Molecules Using a Sparse Additive Belief Model
We present a sparse knowledge gradient (SpKG) algorithm for adaptively
selecting the targeted regions within a large RNA molecule to identify which
regions are most amenable to interactions with other molecules. Experimentally,
such regions can be inferred from fluorescence measurements obtained by binding
a complementary probe with fluorescence markers to the targeted regions. We use
a biophysical model which shows that the fluorescence ratio under the log scale
has a sparse linear relationship with the coefficients describing the
accessibility of each nucleotide, since not all sites are accessible (due to
the folding of the molecule). The SpKG algorithm uniquely combines the Bayesian
ranking and selection problem with the frequentist regularized
regression approach Lasso. We use this algorithm to identify the sparsity
pattern of the linear model as well as sequentially decide the best regions to
test before experimental budget is exhausted. Besides, we also develop two
other new algorithms: batch SpKG algorithm, which generates more suggestions
sequentially to run parallel experiments; and batch SpKG with a procedure which
we call length mutagenesis. It dynamically adds in new alternatives, in the
form of types of probes, are created by inserting, deleting or mutating
nucleotides within existing probes. In simulation, we demonstrate these
algorithms on the Group I intron (a mid-size RNA molecule), showing that they
efficiently learn the correct sparsity pattern, identify the most accessible
region, and outperform several other policies
CMOS-3D smart imager architectures for feature detection
This paper reports a multi-layered smart image sensor architecture for feature extraction based on detection of interest points. The architecture is conceived for 3-D integrated circuit technologies consisting of two layers (tiers) plus memory. The top tier includes sensing and processing circuitry aimed to perform Gaussian filtering and generate Gaussian pyramids in fully concurrent way. The circuitry in this tier operates in mixed-signal domain. It embeds in-pixel correlated double sampling, a switched-capacitor network for Gaussian pyramid generation, analog memories and a comparator for in-pixel analog-to-digital conversion. This tier can be further split into two for improved resolution; one containing the sensors and another containing a capacitor per sensor plus the mixed-signal processing circuitry. Regarding the bottom tier, it embeds digital circuitry entitled for the calculation of Harris, Hessian, and difference-of-Gaussian detectors. The overall system can hence be configured by the user to detect interest points by using the algorithm out of these three better suited to practical applications. The paper describes the different kind of algorithms featured and the circuitry employed at top and bottom tiers. The Gaussian pyramid is implemented with a switched-capacitor network in less than 50 μs, outperforming more conventional solutions.Xunta de Galicia 10PXIB206037PRMinisterio de Ciencia e Innovación TEC2009-12686, IPT-2011-1625-430000Office of Naval Research N00014111031
Characterization of femtosecond laser written waveguides for integrated biochemical sensing
Fluorescence detection is known to be one of the most sensitive among the different optical sensing techniques. This work focuses on excitation and detection of fluorescence emitted by DNA strands labeled with fluorescent dye molecules that can be excited at a specific wavelength. Excitation occurs via optical channel waveguides written with femtosecond laser pulses applied coplanar with a microfluidic channel on a glass chip. The waveguides are optically characterized in order to facilitate the design of sensing structures which can be applied for monitoring the spatial separation of biochemical\ud
species as a result of capillary electrophoresis
Radiation hardness of small-pitch 3D pixel sensors up to HL-LHC fluences
A new generation of 3D silicon pixel detectors with a small pixel size of
5050 and 25100 m is being developed for the HL-LHC
tracker upgrades. The radiation hardness of such detectors was studied in beam
tests after irradiation to HL-LHC fluences up to
n/cm. At this fluence, an operation voltage of only 100 V
is needed to achieve 97% hit efficiency, with a power dissipation of 13
mW/cm at -25C, considerably lower than for previous 3D sensor
generations and planar sensors.Comment: 5 pages, 2 figures, Proceedings of TIPP 2017, Beijing (International
Conference on The Technology and Instrumentation in Particle Physics 2017
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