39 research outputs found
Inflaton Fragmentation and Oscillon Formation in Three Dimensions
Analytical arguments suggest that a large class of scalar field potentials
permit the existence of oscillons -- pseudo-stable, non-topological solitons --
in three spatial dimensions. In this paper we numerically explore oscillon
solutions in three dimensions. We confirm the existence of these field
configurations as solutions to the Klein-Gorden equation in an expanding
background, and verify the predictions of Amin and Shirokoff for the
characteristics of individual oscillons for their model. Further, we
demonstrate that significant numbers of oscillons can be generated via
fragmentation of the inflaton condensate, consistent with the analysis of Amin.
These emergent oscillons can easily dominate the post-inflationary universe.
Finally, both analytic and numerical results suggest that oscillons are stable
on timescales longer than the post-inflationary Hubble time. Consequently, the
post-inflationary universe can contain an effective matter-dominated phase,
during which it is dominated by localized concentrations of scalar field
matter.Comment: See http://easther.physics.yale.edu/downloads.html for numerical
codes. Visualizations available at http://www.mit.edu/~mamin/oscillons.html
and http://easther.physics.yale.edu/fields.html V2 Minor fixes to reference
lis
Microbial Associations With Microscopic Colitis
INTRODUCTION: Microscopic colitis is a relatively common cause of chronic diarrhea and may be linked to luminal factors. Given the essential role of the microbiome in human gut health, analysis of microbiome changes associated with microscopic colitis could provide insights into the development of the disease. METHODS: We enrolled patients who underwent colonoscopy for diarrhea. An experienced pathologist classified patients as having microscopic colitis (n = 52) or controls (n = 153). Research biopsies were taken from the ascending (ASC) and descending (DES) colon, and the microbiome was characterized with Illumina sequencing. We analyzed the associations between microscopic colitis and microbiome with a series of increasingly complex models adjusted for a range of demographic and health factors. RESULTS: We found that alpha diversity was significantly lower in cases with microscopic colitis compared with that in controls in the DES colon microbiome. In the DES colon, a series of models that adjusted for an increasing number of covariates found taxa significantly associated with microscopic colitis, including Proteobacteria that was enriched in cases and Collinsella that was enriched in controls. While the alpha diversity and taxa were not significantly associated with microscopic colitis in the ASC colon microbiome, the inference P values based on ASC and DES microbiomes were highly correlated. DISCUSSION: Our study demonstrates an altered microbiome in cases with microscopic colitis compared with that in controls. Because both the cases and controls experienced diarrhea, we have identified candidate taxa that could be mechanistically responsible for the development of microscopic colitis independent of changes to the microbial community caused by diarrhea
Dietary calcium and risk of microscopic colitis
BACKGROUND: Microscopic colitis is an increasingly common cause of watery diarrhea particularly in older individuals. The role of diet in microscopic colitis has received little study. METHODS: We conducted a case-control study at a single institution enrolling patients referred for elective, outpatient colonoscopy for diarrhea. Patients were classified as microscopic colitis cases or non-microscopic colitis controls following review of colon biopsies by one research pathologist. Study subjects were interviewed by a trained telephone interviewer using a validated food frequency questionnaire. Adherent microbes were evaluated from colonic biopsies using 16s rRNA sequencing. RESULTS: The study population included 106 microscopic colitis cases and 215 controls. Compared to controls, the cases were older, better educated and more likely to be female. Microscopic colitis cases had lower body mass index (BMI) and were more likely to have lost weight. Subjects in the highest quartile of dietary calcium intake had a lower risk of microscopic colitis compared to the lowest quartile, adjusted odds ratio 0.22, 95% confidence interval 0.07-0.76). The findings were not explained by dairy intake, body mass index or weight loss. We found that dietary calcium intake had significant associations with the abundance of Actinobacteria and Coriobacteriales in the microbial community of colonic biopsies. CONCLUSIONS: Compared to patients with diarrhea, microscopic colitis cases had lower intake of dietary calcium. Diet can be associated with alterations in the gut microbiota and with luminal factors that could affect risk for microscopic colitis
Escape from washing out of baryon number in a two-zero-texture general Zee model compatible with the large mixing angle MSW solution
We propose a two-zero-texture general Zee model, compatible with the large
mixing angle Mikheyev-Smirnov-Wolfenstein solution. The washing out of the
baryon number does not occur in this model for an adequate parameter range. We
check the consistency of a model with the constraints coming from flavor
changing neutral current processes, the recent cosmic microwave background
observation, and the Z-burst scenario.Comment: 22 pages, 2 eps figures, Type set revtex
Direct comparison of phase-space distributions of K- and K+ mesons in heavy-ion collisions at SIS energies - evidence for in-medium modifications of kaons ?
The ratio of K- to K+ meson yields has been measured in the systems RuRu at
1.69 A GeV, Ru+Zr at 1.69 A GeV, and Ni+Ni at 1.93 A GeV incident beam kinetic
energy. The yield ratio is observed to vary across the measured phase space.
Relativistic transport-model calculations indicate that the data are best
understood if in-medium modifications of the kaons are taken into account.Comment: 14 pages including 3 figure
Sideward flow of K+ mesons in Ru+Ru and Ni+Ni reactions near threshold
Experimental data on K+ meson and proton sideward flow measured with the FOPI
detector at SIS/GSI in the reactions Ru+Ru at 1.69 AGeV and Ni+Ni at 1.93 AGeV
are presented. The K+ sideward flow is found to be anti-correlated (correlated)
with the one of protons at low (high) transverse momenta. When compared to the
predictions of a transport model, the data favour the existence of an in-medium
repulsive K+ nucleon potential.Comment: 16 pages Revtex, 3 ps-figures, submitted to Phys. Lett.
Hybrid Stars in a Strong Magnetic Field
We study the effects of high magnetic fields on the particle population and
equation of state of hybrid stars using an extended hadronic and quark SU(3)
non-linear realization of the sigma model. In this model the degrees of freedom
change naturally from hadrons to quarks as the density and/or temperature
increases. The effects of high magnetic fields and anomalous magnetic moment
are visible in the macroscopic properties of the star, such as mass, adiabatic
index, moment of inertia, and cooling curves. Moreover, at the same time that
the magnetic fields become high enough to modify those properties, they make
the star anisotropic.Comment: Revised version with updated reference
Formation of dense partonic matter in relativistic nucleus-nucleus collisions at RHIC: Experimental evaluation by the PHENIX collaboration
Extensive experimental data from high-energy nucleus-nucleus collisions were
recorded using the PHENIX detector at the Relativistic Heavy Ion Collider
(RHIC). The comprehensive set of measurements from the first three years of
RHIC operation includes charged particle multiplicities, transverse energy,
yield ratios and spectra of identified hadrons in a wide range of transverse
momenta (p_T), elliptic flow, two-particle correlations, non-statistical
fluctuations, and suppression of particle production at high p_T. The results
are examined with an emphasis on implications for the formation of a new state
of dense matter. We find that the state of matter created at RHIC cannot be
described in terms of ordinary color neutral hadrons.Comment: 510 authors, 127 pages text, 56 figures, 1 tables, LaTeX. Submitted
to Nuclear Physics A as a regular article; v3 has minor changes in response
to referee comments. Plain text data tables for the points plotted in figures
for this and previous PHENIX publications are (or will be) publicly available
at http://www.phenix.bnl.gov/papers.htm