4,913 research outputs found
Evolution of the Pancaking Effect in a LCDM Cosmology
We explore the evolution of the large-scale anisotropy in the velocity field
caused by the gravitational pancaking effect assuming a LCDM universe. The
Millennium Run halo catalogs at four different redshifts, z=0, 0.5, 1 and z=2
are analyzed to find that the pancaking effect starts to intervene the
hierarchical structure formation at redshift z=2 when a characteristic pancake
scale is around 3 Mpc/h. It is also clearly shown how the degree and scale of
the pancaking effect changes with time. An analytic model based on the
Zel'dovich approximation is presented to explain quantitatively the evolution
of the velocity-pancake alignment. A cosmological implication of our finding
and a possibility of detecting a signal in real universe are discussed.Comment: accepted by ApJ, 21 pages, 6 figures, discussion and error analysis
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Concise Review: The Potential Use of Intestinal Stem Cells to Treat Patients With Intestinal Failure.
: Intestinal failure is a rare life-threatening condition that results in the inability to maintain normal growth and hydration status by enteral nutrition alone. Although parenteral nutrition and whole organ allogeneic transplantation have improved the survival of these patients, current therapies are associated with a high risk for morbidity and mortality. Development of methods to propagate adult human intestinal stem cells (ISCs) and pluripotent stem cells raises the possibility of using stem cell-based therapy for patients with monogenic and polygenic forms of intestinal failure. Organoids have demonstrated the capacity to proliferate indefinitely and differentiate into the various cellular lineages of the gut. Genome-editing techniques, including the overexpression of the corrected form of the defective gene, or the use of CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 to selectively correct the monogenic disease-causing variant within the stem cell, make autologous ISC transplantation a feasible approach. However, numerous techniques still need to be further optimized, including more robust ex vivo ISC expansion, native ISC ablation, and engraftment protocols. Large-animal models can to be used to develop such techniques and protocols and to establish the safety of autologous ISC transplantation because outcomes in such models can be extrapolated more readily to humans.The field of intestinal stem cell biology has exploded over the past 5 years with discoveries related to in vivo and in vitro stem cell identity and function. The goal of this review article is to highlight the potential use of these cells to treat various epithelial disorders of the gut and discuss the various roadblocks that will be encountered in the coming years
Direct sampling of the Susskind-Glogower phase distributions
Coarse-grained phase distributions are introduced that approximate to the
Susskind--Glogower cosine and sine phase distributions. The integral relations
between the phase distributions and the phase-parametrized field-strength
distributions observable in balanced homodyning are derived and the integral
kernels are analyzed. It is shown that the phase distributions can be directly
sampled from the field-strength distributions which offers the possibility of
measuring the Susskind--Glogower cosine and sine phase distributions with
sufficiently well accuracy. Numerical simulations are performed to demonstrate
the applicability of the method.Comment: 10 figures using a4.st
Detecting the degree of macroscopic quantumness using an overlap measurement
We investigate how to experimentally detect a recently proposed measure to
quantify macroscopic quantum superpositions [Phys. Rev. Lett. 106, 220401
(2011)], namely, "macroscopic quantumness" . Schemes based on
overlap measurements for harmonic oscillator states and for qubit states are
extensively investigated. Effects of detection inefficiency and coarse-graining
are analyzed in order to assess feasibility of the schemes.Comment: 12 pages, 8 figures, to be published in J. Opt. Soc. Am.
Position-dependent diffusion of light in disordered waveguides
Diffusion has been widely used to describe a random walk of particles or
waves, and it requires only one parameter -- the diffusion constant. For waves,
however, diffusion is an approximation that disregards the possibility of
interference. Anderson localization, which manifests itself through a vanishing
diffusion coefficient in an infinite system, originates from constructive
interference of waves traveling in loop trajectories -- pairs of time-reversed
paths returning to the same point. In an open system of finite size, the return
probability through such paths is reduced, particularly near the boundary where
waves may escape. Based on this argument, the self-consistent theory of
localization and the supersymmetric field theory predict that the diffusion
coefficient varies spatially inside the system. A direct experimental
observation of this effect is a challenge because it requires monitoring wave
transport inside the system. Here, we fabricate two-dimensional photonic random
media and probe position-dependent diffusion inside the sample from the third
dimension. By varying the geometry of the system or the dissipation which also
limits the size of loop trajectories, we are able to control the
renormalization of the diffusion coefficient. This work shows the possibility
of manipulating diffusion via the interplay of localization and dissipation.Comment: 24 pages, 6 figure
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