393 research outputs found
Moduli of quantum Riemannian geometries on <= 4 points
We classify parallelizable noncommutative manifold structures on finite sets
of small size in the general formalism of framed quantum manifolds and
vielbeins introduced previously. The full moduli space is found for
points, and a restricted moduli space for 4 points. The topological part of the
moduli space is found for points based on the known atlas of regular
graphs. We also discuss aspects of the quantum theory defined by functional
integration.Comment: 34 pages ams-latex, 4 figure
Electromagnetism and Gauge Theory on the Permutation Group
Using noncommutative geometry we do U(1) gauge theory on the permutation
group . Unlike usual lattice gauge theories the use of a nonAbelian group
here as spacetime corresponds to a background Riemannian curvature. In this
background we solve spin 0, 1/2 and spin 1 equations of motion, including the
spin 1 or `photon' case in the presence of sources, i.e. a theory of classical
electromagnetism. Moreover, we solve the U(1) Yang-Mills theory (this differs
from the U(1) Maxwell theory in noncommutative geometry), including the moduli
spaces of flat connections. We show that the Yang-Mills action has a simple
form in terms of Wilson loops in the permutation group, and we discuss aspects
of the quantum theory.Comment: 28 pages, LaTex as revised March 2001 -- expanded remarks in last
section on the quantum theory, but no sig. change
The expected neutral frequency spectrum of linked sites
We present an exact, closed expression for the expected neutral Site
Frequency Spectrum for two neutral sites, 2-SFS, without recombination. This
spectrum is the immediate extension of the well known single site
neutral SFS. Similar formulae are also provided for the case of the expected
SFS of sites that are linked to a focal neutral mutation of known frequency.
Formulae for finite samples are obtained by coalescent methods and remarkably
simple expressions are derived for the SFS of a large population, which are
also solutions of the multi-allelic Kolmogorov equations. Besides the general
interest of these new spectra, they relate to interesting biological cases such
as structural variants and introgressions. As an example, we present the
expected neutral frequency spectrum of regions with a chromosomal inversion.Comment: 26 pages, 5 figure
Field Localization and Enhancement of Phase Locked Second and Third Harmonic Generation in Absorbing Semiconductor Cavities
We predict and experimentally observe the enhancement by three orders of
magnitude of phase mismatched second and third harmonic generation in a GaAs
cavity at 650nm and 433nm, respectively, well above the absorption edge. Phase
locking between the pump and the harmonics changes the effective dispersion of
the medium and inhibits absorption. Despite hostile conditions the harmonics
become localized inside the cavity leading to relatively large conversion
efficiencies. Field localization plays a pivotal role and ushers in a new class
of semiconductor-based devices in the visible and UV ranges
Field theory for size- and charge asymmetric primitive model of electrolytes. Mean-field stability analysis and pretransitional effects
The primitive model of ionic systems is investigated within a field-theoretic
description for the whole range of size-, \lambda, and charge, Z, ratios of the
two ionic species. Two order parameters (OP) are identified, and their
relations to physically relevant quantities are described for various values of
\lambda and Z. Instabilities of the disordered phase associated with the two
OP's are determined in the mean-field approximation.
A gas-liquid separation occurs for any Z and \lambda different from 1. In
addition, an instability with respect to various types of periodic ordering of
the two kinds of ions is found
Palaeoclimatic and palaeoenvironmental evolution of the Lower Pleistocene Arda River succession
The Arda River marine succession, cropping out in western Emilia (northern Italy) represents an excellent site to study past ecosystems dynamics in the frame of Early Pleistocene climate change and tectonic activity. This one-day excursion leads the participants to discover the palaeoclimatic and palaeoenvironmental evolution of the Lower Pleistocene Arda River marine section, unraveled through an integrated use of sedimentological, palaeoecological (molluscs and trace fossils) and geochemical tools. Upsection, the succession was deposited in progressively shallower water and colder climate during phases of advance of fan deltas affected by hyperpycnal flows. It culminates at the top with clast supported alluvial conglomerates and freshwater/terrestrial biota indicating a sea level drop and the establishment of a continental environment. It is very rich in fossils: in the marine part molluscs, brachiopods, corals and echinoderms, besides well preserved trace fossils, are abundant; whereas in the continental part a mammal fauna and freshwater/terrestrial molluscs are occasionally found. Sclerochemical analyses undertaken on bivalve shells indicate that seawater temperature seasonality was the main variable of climate change within the study area during the Early Pleistocene. In particular, strong seasonality and low winter palaeotemperatures were assumed to be the main drivers for the widespread establishment of Arctica islandica populations in the palaeo-Adriatic Sea around 1.80 Ma. During the excursion not only fossils are shown, but also interesting biocalcarenitic bodies with a complex geometry cropping out in the town of Castell\u2019Arquato. The excursion is complemented by the visit to the Giuseppe Cortesi geological and palaeontological museum, housing vertebrate and invertebrate fossil collections
Allergy to polyethilenglicole of anti-sars cov2 vaccine recipient: A case report of young adult recipient and the management of future exposure to sars-cov2
The main contraindication to the anti-SARS CoV2 vaccine is an anaphylactic reaction to a vaccine component. The need to vaccinate allergic people who are at higher risk can be of public health interest and this report shows a case of an allergic reaction to PEG of a HCW who had received the first dose of anti-SARS CoV2 vaccine. For 5 h after the administration of the vaccine, she had the appearance of erythematous spots on the face and neck, and a feeling of a slurred mouth and hoarseness. In order to treat the event, she was administered 8 mg intravenous dexamethasone, 1 vial intravenous chlorphenamine maleate, 250 mL intravenous 0.9% NaCl, and conventional oxygen therapy (2 L/min) with complete resolution of the suspected adverse drug reaction. According to the contraindication to the cutaneous test for this patient, BAT was used for further investigations. The patient who suffered the adverse reaction to the COVID-19 vaccine and other five allergic patients who did not report any adverse reaction after the vaccination were tested. There was a significant activation of the vaccine-reactive patientâs basophils with 14.79 CD203chigh% at the concentration of 0.2 mg/mL, while other patients were negative. People who have a confirmed reaction to a vaccine component should undergo further investigation to discover other possible cross-reactions and select the right vaccine to immunize them
Theory of solvation in polar nematics
We develop a linear response theory of solvation of ionic and dipolar solutes
in anisotropic, axially symmetric polar solvents. The theory is applied to
solvation in polar nematic liquid crystals. The formal theory constructs the
solvation response function from projections of the solvent dipolar
susceptibility on rotational invariants. These projections are obtained from
Monte Carlo simulations of a fluid of dipolar spherocylinders which can exist
both in the isotropic and nematic phase. Based on the properties of the solvent
susceptibility from simulations and the formal solution, we have obtained a
formula for the solvation free energy which incorporates experimentally
available properties of nematics and the length of correlation between the
dipoles in the liquid crystal. Illustrative calculations are presented for the
Stokes shift and Stokes shift correlation function of coumarin-153 in
4-n-pentyl-4'-cyanobiphenyl (5CB) and 4,4-n-heptyl-cyanopiphenyl (7CB) solvents
as a function of temperature in both the nematic and isotropic phase.Comment: 19 pages, 9 figure
Mesoscopic theory for size- and charge- asymmetric ionic systems. I. Case of extreme asymmetry
A mesoscopic theory for the primitive model of ionic systems is developed for
arbitrary size, , and charge, ,
asymmetry. Our theory is an extension of the theory we developed earlier for
the restricted primitive model. The case of extreme asymmetries
and is studied in some detail in a mean-field
approximation. The phase diagram and correlation functions are obtained in the
asymptotic regime and , and for infinite
dilution of the larger ions (volume fraction or less). We find a
coexistence between a very dilute 'gas' phase and a crystalline phase in which
the macroions form a bcc structure with the lattice constant . Such coexistence was observed experimentally in deionized aqueous
solutions of highly charged colloidal particles
Asymmetric Primitive-Model Electrolytes: Debye-Huckel Theory, Criticality and Energy Bounds
Debye-Huckel (DH) theory is extended to treat two-component size- and
charge-asymmetric primitive models, focussing primarily on the 1:1 additive
hard-sphere electrolyte with, say, negative ion diameters, a--, larger than the
positive ion diameters, a++. The treatment highlights the crucial importance of
the charge-unbalanced ``border zones'' around each ion into which other ions of
only one species may penetrate. Extensions of the DH approach which describe
the border zones in a physically reasonable way are exact at high and low
density, , and, furthermore, are also in substantial agreement with
recent simulation predictions for \emph{trends} in the critical parameters,
and , with increasing size asymmetry. Conversely, the simplest
linear asymmetric DH description, which fails to account for physically
expected behavior in the border zones at low , can violate a new lower bound
on the energy (which applies generally to models asymmetric in both charge and
size). Other recent theories, including those based on the mean spherical
approximation, have predicted trends in the critical parameters quite opposite
to those established by the simulations.Comment: to appear in Physical Review
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