8,836 research outputs found
New Darboux Transformation for Hirota-Satsuma coupled KdV System
A new Darboux transformation is presented for the Hirota-Satsuma coupled KdV
system. It is shown that this Darboux transformation can be constructed by
means of two methods: Painlev\'{e} analysis and reduction of a binary Darboux
transformation. By iteration of the Darboux transformation, the Grammian type
solutions are found for the coupled KdV system.Comment: LaTeX 2.09, 10 page
Holographic Algorithm with Matchgates Is Universal for Planar CSP Over Boolean Domain
We prove a complexity classification theorem that classifies all counting
constraint satisfaction problems (CSP) over Boolean variables into exactly
three categories: (1) Polynomial-time tractable; (2) P-hard for general
instances, but solvable in polynomial-time over planar graphs; and (3)
P-hard over planar graphs. The classification applies to all sets of local,
not necessarily symmetric, constraint functions on Boolean variables that take
complex values. It is shown that Valiant's holographic algorithm with
matchgates is a universal strategy for all problems in category (2).Comment: 94 page
Lensless high-resolution on-chip optofluidic microscopes for Caenorhabditis elegans and cell imaging
Low-cost and high-resolution on-chip microscopes are vital for reducing cost and improving efficiency for modern biomedicine and bioscience. Despite the needs, the conventional microscope design has proven difficult to miniaturize. Here, we report the implementation and application of two high-resolution (≈0.9 μm for the first and ≈0.8 μm for the second), lensless, and fully on-chip microscopes based on the optofluidic microscopy (OFM) method. These systems abandon the conventional microscope design, which requires expensive lenses and large space to magnify images, and instead utilizes microfluidic flow to deliver specimens across array(s) of micrometer-size apertures defined on a metal-coated CMOS sensor to generate direct projection images. The first system utilizes a gravity-driven microfluidic flow for sample scanning and is suited for imaging elongate objects, such as Caenorhabditis elegans; and the second system employs an electrokinetic drive for flow control and is suited for imaging cells and other spherical/ellipsoidal objects. As a demonstration of the OFM for bioscience research, we show that the prototypes can be used to perform automated phenotype characterization of different Caenorhabditis elegans mutant strains, and to image spores and single cellular entities. The optofluidic microscope design, readily fabricable with existing semiconductor and microfluidic technologies, offers low-cost and highly compact imaging solutions. More functionalities, such as on-chip phase and fluorescence imaging, can also be readily adapted into OFM systems. We anticipate that the OFM can significantly address a range of biomedical and bioscience needs, and engender new microscope applications
Towards a warped inflationary brane scanning
We present a detailed systematics for comparing warped brane inflation with
the observations, incorporating the effects of both moduli stabilization and
ultraviolet bulk physics. We explicitly construct an example of the inflaton
potential governing the motion of a mobile D3 brane in the entire warped
deformed conifold. This allows us to precisely identify the corresponding
scales of the cosmic microwave background. The effects due to bulk fluxes or
localized sources are parametrized using gauge/string duality. We next perform
some sample scannings to explore the parameter space of the complete potential,
and first demonstrate that without the bulk effects there can be large
degenerate sets of parameters with observationally consistent predictions. When
the bulk perturbations are included, however, the observational predictions are
generally spoiled. For them to remain consistent, the magnitudes of the bulk
effects need to be highly suppressed via fine tuning.Comment: (v1) 11 pages, 2 figures, 2 tables; (v2) more clarifications and
references added; (v3) 12 pages, more discussions, to appear in Physical
Review
Boundary effects to the entanglement entropy and two-site entanglement of the spin-1 valence-bond solid
We investigate the von Neumann entropy of a block of subsystem for the
valence-bond solid (VBS) state with general open boundary conditions. We show
that the effect of the boundary on the von Neumann entropy decays exponentially
fast in the distance between the subsystem considered and the boundary sites.
Further, we show that as the size of the subsystem increases, its von Neumann
entropy exponentially approaches the summation of the von Neumann entropies of
the two ends, the exponent being related to the size. In contrast to critical
systems, where boundary effects to the von Neumann entropy decay slowly, the
boundary effects in a VBS, a non-critical system, decay very quickly. We also
study the entanglement between two spins.
Curiously, while the boundary operators decrease the von Neumann entropy of L
spins, they increase the entanglement between two spins.Comment: 4 pages, 2 figures. Physical Review B (in press
Atmospheric Dynamics of Hot Exoplanets
The characterization of exoplanetary atmospheres has come of age in the last
decade, as astronomical techniques now allow for albedos, chemical abundances,
temperature profiles and maps, rotation periods and even wind speeds to be
measured. Atmospheric dynamics sets the background state of density,
temperature and velocity that determines or influences the spectral and
temporal appearance of an exoplanetary atmosphere. Hot exoplanets are most
amenable to these characterization techniques; in the present review, we focus
on highly-irradiated, large exoplanets (the "hot Jupiters"), as astronomical
data begin to confront theoretical questions. We summarize the basic
atmospheric quantities inferred from the astronomical observations. We review
the state of the art by addressing a series of current questions and look
towards the future by considering a separate set of exploratory questions.
Attaining the next level of understanding will require a concerted effort of
constructing multi-faceted, multi-wavelength datasets for benchmark objects.
Understanding clouds presents a formidable obstacle, as they introduce
degeneracies into the interpretation of spectra, yet their properties and
existence are directly influenced by atmospheric dynamics. Confronting general
circulation models with these multi-faceted, multi-wavelength datasets will
help us understand these and other degeneracies. The coming decade will witness
a decisive confrontation of theory and simulation by the next generation of
astronomical data.Comment: Accepted by Annual Review of Earth and Planetary Sciences. 32 pages,
9 figures, 1 table. Posted with permission from the Annual Review of Earth
and Planetary Sciences, Volume 43 by Annual Reviews,
http://www.annualreviews.or
Entanglement-assisted local operations and classical communications conversion in the quantum critical systems
Conversions between the ground states in quantum critical systems via
entanglement-assisted local operations and classical communications (eLOCC) are
studied. We propose a new method to reveal the different convertibility by
local operations when a quantum phase transition occurs. We have studied the
ground state local convertibility in the one dimensional transverse field Ising
model, XY model and XXZ model. It is found that the eLOCC convertibility sudden
changes at the phase transition points. In transverse field Ising model the
eLOCC convertibility between the first excited state and the ground state are
also distinct for different phases. The relation between the order of quantum
phase transitions and the local convertibility is discussed.Comment: 7 pages, 5 figures, 5 table
Null-stream veto for two co-located detectors: Implementation issues
Time-series data from multiple gravitational wave (GW) detectors can be
linearly combined to form a null-stream, in which all GW information will be
cancelled out. This null-stream can be used to distinguish between actual GW
triggers and spurious noise transients in a search for GW bursts using a
network of detectors. The biggest source of error in the null-stream analysis
comes from the fact that the detector data are not perfectly calibrated. In
this paper, we present an implementation of the null-stream veto in the
simplest network of two co-located detectors. The detectors are assumed to have
calibration uncertainties and correlated noise components. We estimate the
effect of calibration uncertainties in the null-stream veto analysis and
propose a new formulation to overcome this. This new formulation is
demonstrated by doing software injections in Gaussian noise.Comment: Minor changes; To appear in Class. Quantum Grav. (Proc. GWDAW10
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