964 research outputs found
Stress and Strain in Flat Piling of Disks
We have created a flat piling of disks in a numerical experiment using the
Distinct Element Method (DEM) by depositing them under gravity. In the
resulting pile, we then measured increments in stress and strain that were
associated with a small decrease in gravity. We first describe the stress in
terms of the strain using isotropic elasticity theory. Then, from a
micro-mechanical view point, we calculate the relation between the stress and
strain using the mean strain assumption. We compare the predicted values of
Young's modulus and Poisson's ratio with those that were measured in the
numerical experiment.Comment: 9 pages, 1 table, 8 figures, and 2 pages for captions of figure
Smoothed Particle Hydrodynamics for Relativistic Heavy Ion Collisions
The method of smoothed particle hydrodynamics (SPH) is developped
appropriately for the study of relativistic heavy ion collision processes. In
order to describe the flow of a high energy but low baryon number density
fluid, the entropy is taken as the SPH base. We formulate the method in terms
of the variational principle. Several examples show that the method is very
promising for the study of hadronic flow in RHIC physics.Comment: 14 pages, 8figure
Force correlations and arches formation in granular assemblies
In the context of a simple microscopic schematic scalar model we study the
effects of spatial correlations in force transmission in granular assemblies.
We show that the parameters of the normalized weights distribution function,
, strongly depend on the spatial extensions,
, of such correlations. We show, then, the connections between
measurable macroscopic quantities and microscopic mechanisms enhancing
correlations. In particular we evaluate how the exponential cut-off,
, and the small forces power law exponent, , depend
on the correlation length, . If correlations go to infinity, weights are
power law distributed.Comment: 6 page
Fluctuations of the Initial Conditions and the Continuous Emission in Hydrodynamic Description of Two-Pion Interferometry
Within hydrodynamic approach, we study the Bose-Einstein correlation of
identical pions by taking into account both event-by-event fluctuating initial
conditions and continuous pion emission during the whole development of the hot
and dense matter formed in high-energy collisions. Considerable deviations
occur, compared to the usual hydro calculations with smooth initial conditions
and a sudden freeze-out on a well defined hypersurface. Comparison with data at
RHIC shows that, despite rather rough approximation we used here, this
description can give account of the dependence of and and
improves considerably the one for with respect to the usual version.Comment: 5 pages, 4 figure
Consistent Treatment of Soft and Hard Processes in Hadronic Interactions
The QCD improved parton model is a very successful concept to treat processes
in hadronic interactions, whenever large partonic transverse momenta are
involved. However, cross sections diverge in the limit p_T -> 0, and the usual
treatment is the definition of a lower cutoff p_T_min, such that processes with
a smaller p_T -- so-called soft processes -- are simply ignored, which is
certainly not correct for example at RHIC energies. A more consistent procedure
amounts to introduce a technical parameter Q_0^2, referred to as soft
virtuality scale, which is nothing but an artificial borderline between soft
and hard physics. We will discuss such a formalism, which coincides with the
improved parton model for high p_T processes and with the phenomenological
treatment of soft scattering, when only small virtualities are involved. The
most important aspect of our approach is that it allows to obtain a smooth
transition between soft and hard scattering, and therefore no artificial
dependence on a cutoff parameter should appear.Comment: 19 pages, 19 figure
Upregulation of virulence genes promotes Vibrio cholerae biofilm hyperinfectivity
Vibrio cholerae remains a major global health threat, disproportionately impacting parts of the world without adequate infrastructure and sanitation resources. In aquatic environments, V. cholerae exists both as planktonic cells and as biofilms, which are held together by an extracellular matrix. V. cholerae biofilms have been shown to be hyperinfective, but the mechanism of hyperinfectivity is unclear. Here we show that biofilm-grown cells, irrespective of the surfaces on which they are formed, are able to markedly outcompete planktonic-grown cells in the infant mouse. Using an imaging technique designed to render intestinal tissue optically transparent and preserve the spatial integrity of infected intestines, we reveal and compare three-dimensional V. cholerae colonization patterns of planktonic-grown and biofilm-grown cells. Quantitative image analyses show that V. cholerae colonizes mainly the medial portion of the small intestine and that both the abundance and localization patterns of biofilm-grown cells differ from that of planktonic-grown cells. In vitro biofilm-grown cells activate expression of the virulence cascade, including the toxin coregulated pilus (TCP), and are able to acquire the cholera toxin-carrying CTXĐ€ phage. Overall, virulence factor gene expression is also higher in vivo when infected with biofilm-grown cells, and modulation of their regulation is sufficient to cause the biofilm hyperinfectivity phenotype. Together, these results indicate that the altered biogeography of biofilm-grown cells and their enhanced production of virulence factors in the intestine underpin the biofilm hyperinfectivity phenotype
The KATRIN Pre-Spectrometer at reduced Filter Energy
The KArlsruhe TRItium Neutrino experiment, KATRIN, will determine the mass of
the electron neutrino with a sensitivity of 0.2 eV (90% C.L.) via a measurement
of the beta-spectrum of gaseous tritium near its endpoint of E_0 =18.57 keV. An
ultra-low background of about b = 10 mHz is among the requirements to reach
this sensitivity. In the KATRIN main beam-line two spectrometers of MAC-E
filter type are used in a tandem configuration. This setup, however, produces a
Penning trap which could lead to increased background. We have performed test
measurements showing that the filter energy of the pre-spectrometer can be
reduced by several keV in order to diminish this trap. These measurements were
analyzed with the help of a complex computer simulation, modeling multiple
electron reflections both from the detector and the photoelectric electron
source used in our test setup.Comment: 22 pages, 12 figure
Gender incongruence of adolescence and adulthood: acceptability and clinical utility of the World Health Organizationâs proposed ICD-11 criteria
The World Health Organization (WHO) is currently updating the tenth version of their diagnostic tool, the International Classification of Diseases (ICD, WHO, 1992). Changes have been proposed for the diagnosis of Transsexualism (ICD-10) with regard to terminology, placement and content. The aim of this study was to gather the opinions of transgender individuals (and their relatives/partners) and clinicians in the Netherlands, Flanders (Belgium) and the United Kingdom regarding the proposed changes and the clinical applicability and utility of the ICD-11 criteria of âGender Incongruence of Adolescence and Adulthoodâ (GIAA). A total of 628 participants were included in the study: 284 from the Netherlands (45.2%), 8 from Flanders (Belgium) (1.3%), and 336 (53.5%) from the UK. Most participants were transgender people (or their partners/relatives) (n = 522), 89 participants were healthcare providers (HCPs) and 17 were both healthcare providers and (partners/relatives of) transgender people. Participants completed an online survey developed for this study. Most participants were in favor of the proposed diagnostic term of âGender Incongruenceâ and thought that this was an improvement on the ICD-10 diagnostic term of âTranssexualismâ. Placement in a separate chapter dealing with Sexual- and Gender-related Health or as a Z-code was preferred by many and only a small number of participants stated that this diagnosis should be excluded from the ICD-11. In the UK, most transgender participants thought there should be a diagnosis related to being trans. However, if it were to be removed from the chapter on âpsychiatric disordersâ, many transgender respondents indicated that they would prefer it to be removed from the ICD in its entirety. There were no large differences between the responses of the transgender participants (or their partners and relatives) and HCPs. HCPs were generally positive about the GIAA diagnosis; most thought the diagnosis was clearly defined and easy to use in their practice or work. The duration of gender incongruence (several months) was seen by many as too short and required a clearer definition. If the new diagnostic term of GIAA is retained, it should not be stigmatizing to individuals. Moving this diagnosis away from the mental and behavioral chapter was generally supported. Access to healthcare was one area where retaining a diagnosis seemed to be of benefit
Overpopulation of in pp collisions: a way to distinguish statistical hadronization from string dynamics
The ratio originating from string decays is predicted
to be larger than unity in proton proton interactions at SPS energies (=160 GeV). The anti-omega dominance increases with decreasing beam energy.
This surprising behavior is caused by the combinatorics of quark-antiquark
production in small and low-mass strings. Since this behavior is not found in a
statistical description of hadron production in proton proton collisions, it
may serve as a key observable to probe the hadronization mechanism in such
collisions.Comment: 4 pages, 4 figure
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