5,125 research outputs found
Phase separation driven by surface diffusion: a Monte Carlo study
We propose a kinetic Ising model to study phase separation driven by surface
diffusion. This model is referred to as "Model S", and consists of the usual
Kawasaki spin-exchange kinetics ("Model B") in conjunction with a kinetic
constraint. We use novel multi-spin coding techniques to develop fast
algorithms for Monte Carlo simulations of Models B and S. We use these
algorithms to study the late stages of pattern dynamics in these systems.Comment: 25 pages, 9 figure
Quantum Entanglement Initiated Super Raman Scattering
It has now been possible to prepare chain of ions in an entangled state and
thus question arises --- how the optical properties of a chain of entangled
ions differ from say a chain of independent particles. We investigate nonlinear
optical processes in such chains. We explicitly demonstrate the possibility of
entanglement produced super Raman scattering. Our results in contrast to
Dicke's work on superradiance are applicable to stimulated processes and are
thus free from the standard complications of multimode quantum electrodynamics.
Our results suggest the possibility of similar enhancement factors in other
nonlinear processes like four wave mixing.Comment: 4 pages, 1 figur
Kinetics of Phase Separation in Fluids: A Molecular Dynamics Study
We present results from extensive 3-d molecular dynamics (MD) simulations of
phase separation kinetics in fluids. A coarse-graining procedure is used to
obtain state-of-the-art MD results. We observe an extended period of temporally
linear growth in the viscous hydrodynamic regime. The morphological similarity
of coarsening in fluids and solids is also quantified. The velocity field is
characterized by the presence of monopole-like defects, which yield a
generalized Porod tail in the corresponding structure factor.Comment: 4 pages, 4 figure
Mass independence and asymmetry of the reaction: Multi-fragmentation as an example
We present our recent results on the fragmentation by varying the mass
asymmetry of the reaction between 0.2 and 0.7 at an incident energy of 250
MeV/nucleon. For the present study, the total mass of the system is kept
constant (ATOT = 152) and mass asymmetry of the reaction is defined by the
asymmetry parameter (? = | (AT - AP)/(AT + AP) |). The measured distributions
are shown as a function of the total charge of all projectile fragments,
Zbound. We see an interesting outcome for rise and fall in the production of
intermediate mass fragments (IMFs) for large asymmetric colliding nuclei. This
trend, however, is completely missing for large asymmetric nuclei. Therefore,
experiments are needed to verify this prediction
Association of Chorioamnionitis with Aberrant Neonatal Gut Colonization and Adverse Clinical Outcomes.
ObjectiveChorioamnionitis (inflammation of the placenta and fetal membranes) and abnormal gastrointestinal colonization have been associated with an increased risk of sepsis and death in preterm infants, but whether chorioamnionitis causes abnormal pioneering gastrointestinal colonization in infants is not known. We determined the relationship between chorioamnionitis, altered infant fecal microbiome indicating abnormal gastrointestinal colonization, and adverse outcomes.Study designPreterm infants ≤ 28 weeks at birth were enrolled from 3 level III NICUs in Cincinnati, Ohio and Birmingham, Alabama. Sequencing for 16S microbial gene was performed on stool samples in the first 3 weeks of life. Chorioamnionitis was diagnosed by placental histology. Late onset sepsis and death outcomes were analyzed in relation to fecal microbiota and chorioamnionitis with or without funisitis (inflammation of the umbilical cord).ResultsOf the 106 enrolled infants, 48 infants had no chorioamnionitis, 32 infants had chorioamnionitis but no funisitis (AC), and 26 infants had chorioamnionitis with funisitis (ACF). The fecal samples from ACF infants collected by day of life 7 had higher relative abundance of family Mycoplasmataceae (phylum Tenericutes), genus Prevotella (phylum Bacteroidetes) and genus Sneathia (phylum Fusobacteria). Further, AC and ACF infants had higher incidence of late-onset sepsis/death as a combined outcome. Presence of specific clades in fecal samples, specifically, order Fusobacteria, genus Sneathia or family Mycoplasmataceae, were significantly associated with higher risk of sepsis or death.ConclusionThe results support the hypothesis that specific alterations in the pioneering infant gastrointestinal microbiota induced by chorioamnionitis predispose to neonatal sepsis or death
A comparison of neuroimaging abnormalities in multiple sclerosis, major depression and chronic fatigue syndrome (Myalgic Encephalomyelitis): is there a common cause?
There is copious evidence of abnormalities in resting-state functional network connectivity states, grey and white matter pathology and impaired cerebral perfusion in patients afforded a diagnosis of multiple sclerosis, major depression or chronic fatigue syndrome (CFS) (myalgic encephalomyelitis). Systemic inflammation may well be a major element explaining such findings. Inter-patient and inter-illness variations in neuroimaging findings may arise at least in part from regional genetic, epigenetic and environmental variations in the functions of microglia and astrocytes. Regional differences in neuronal resistance to oxidative and inflammatory insults and in the performance of antioxidant defences in the central nervous system may also play a role. Importantly, replicated experimental findings suggest that the use of high-resolution SPECT imaging may have the capacity to differentiate patients afforded a diagnosis of CFS from those with a diagnosis of depression. Further research involving this form of neuroimaging appears warranted in an attempt to overcome the problem of aetiologically heterogeneous cohorts which probably explain conflicting findings produced by investigative teams active in this field. However, the ionising radiation and relative lack of sensitivity involved probably preclude its use as a routine diagnostic tool
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