579 research outputs found
Mixing and condensation in a wet granular medium
We have studied the effect of small amounts of added liquid on the dynamic
behavior of a granular system consisting of a mixture of glass beads of two
different sizes. Segregation of the large beads to the top of the sample is
found to depend in a nontrivial way on the liquid content. A transition to
viscoplastic behavior occurs at a critical liquid content, which depends upon
the bead size. We show that this transition can be interpreted as a
condensation due to the hysteretic liquid bridge forces connecting the beads,
and provide the corresponding phase diagram.Comment: submitted to PR
Effect of Pions in Cosmic Rays
The effects of pions for vacuum polarization in background magnetic fields
are considered. The effects of quark condensates is also briefly addresses.
Although these effects are out of the measurement accuracy of laboratory
experiments they may be relevant for gamma-ray burst propagation. In
particular, for emissions from the center of the galaxy, we show that the
mixing between the neutral pion and photons results in a deviation of the
gamma-ray spectrum from the standard power-law in the TeV range.Comment: 6 pages, 3 figures; Based in arXiv:0707.4200 with a new very short
discussion in qq condensates. To appear in the Proceedings of Scadron'7
Precise analysis of pion-pion scattering data from Roy equations and forward dispersion relations
We review our recent analysis of pion-pion scattering data in terms of Roy
equations and Forward Dispersion Relations, and present some preliminary
results in terms of a new set of once-subtracted coupled equations for partial
waves. The first analysis consists of independent fits to the different
pion-pion channels that satisfies rather well the dispersive representation. In
the second analysis we constrain the fit with the dispersion relations. The
latter provides a very precise and model independent description of data using
just analyticity, causality and crossing.Comment: 6 pages, two figures. To appear in the proceedings of the Workshop on
Scalar Mesons and Related Topics, Lisbon, Portugal, 11-16 Feb 200
Precise determination of the sigma pole location from a dispersive analysis
We review how the use of recent precise data on kaon decays together with
forward dispersion relations (FDR) and Roy's equations allow us to determine
the sigma resonance pole position very precisely, by using only experimental
input. In addition, we present preliminary results for a modified set of
Roy-like equations with only one subtraction, that show a remarkable
improvement in the precision around the sigma resonance region. For practical
applications, these results are shown to be very well approximated by a very
simple conformal expansion.Comment: 5 pages, 2 figures. To appear in the proceedings of the Workshop on
Scalar Mesons and Related Topics, Lisbon, Portugal, 11-16 Feb 200
NJL with eight quark interactions: Chiral phases at finite T
The thermodynamic potential and thermal dependence of low lying mass spectra
of scalars and pseudoscalars are evaluated in a generalized Nambu --
Jona-Lasinio model, which incorporates eight-quark interactions. These are
necessary to stabilize the scalar effective potential for the light and strange
quark flavors, which would be otherwise unbounded from below. In addition it
turns out that they are also crucial to i) lower the temperature of the chiral
transition, in conformity with lattice calculations, ii) sharpen the
temperature interval in which the crossover occurs, iii) or even allow for
first order transitions to occur with realistic quark mass values, from certain
critical values of the parameters. These are unprecedented results which cannot
be obtained within the NJL approaches restricted to quartic and six-quark
interactions.Comment: 6 pages, 3 figures, Talk presented at SCADRON 70 Workshop on Scalar
Mesons and Related Topics, Lisbon, 11-16 February 200
Novel population pharmacokinetic approach to explain the differences between cystic fibrosis patients and healthy volunteers via protein binding
The pharmacokinetics in patients with cystic fibrosis (CF) has long been thought to differ considerably from that in healthy volunteers. For highly protein bound beta -lactams, profound pharmacokinetic differences were observed between comparatively morbid patients with CF and healthy volunteers. These differences could be explained by body weight and body composition for beta -lactams with low protein binding. This study aimed to develop a novel population modeling approach to describe the pharmacokinetic differences between both subject groups by estimating protein binding. Eight patients with CF (lean body mass [LBM]: 39.8 +/- 5.4kg) and six healthy volunteers (LBM: 53.1 +/- 9.5kg) received 1027.5 mg cefotiam intravenously. Plasma concentrations and amounts in urine were simultaneously modelled. Unscaled total clearance and volume of distribution were 3% smaller in patients with CF compared to those in healthy volunteers. After allometric scaling by LBM to account for body size and composition, the remaining pharmacokinetic differences were explained by estimating the unbound fraction of cefotiam in plasma. The latter was fixed to 50% in male and estimated as 54.5% in female healthy volunteers as well as 56.3% in male and 74.4% in female patients with CF. This novel approach holds promise for characterizing the pharmacokinetics in special patient populations with altered protein binding
Political Skill Moderates the Success of Psychopaths at the Workplace
On one hand, psychopaths tend to be callous, emotionally deficient, aggressive, self promoting, impulsive, and pursuant of unmitigated agency regardless of the extent to which it comes at the expense of others. On the other hand, by all accounts, psychopaths tend to be charming, seductive, self-confident, composed, risk-seeking, and adept at impression management (Babiak & Hare, 2006; Paulhus & Williams, 2002). Therefore, the purpose of this study was to reconcile these contrasting positions by examining whether (non-violent) psychopaths truly can be âsuccessfulâ in the workplace. Drawing on socioanalytic theory (Hogan, 1983), we hypothesized that psychopaths in possession of political skill would be better able to package, conceal, and/or restrain their desires to get ahead in such a way as to be perceived as less counterproductive and more adaptive. Results provided support for these hypotheses. Implications for theory, practice, and future research are provided in light of a number of notable strengths and limitations
Spherical probes for simultaneous measurement of rotational and translational diffusion in 3 dimensions
Real time visualization and tracking of colloidal particles with 3D
resolution is essential for probing the local structure and dynamics in complex
fluids. Although tracking translational motion of spherical colloids is
well-known, accessing rotational dynamics of such particles remains a great
challenge. Here, we report a novel approach of using fluorescently labeled
raspberry-like colloids with an optical anisotropy to concurrently track
translational and rotational dynamics in 3 dimensions. The raspberry-like
particles are coated by a silica layer of adjustable thickness, which allows
tuning the surface roughness. The synthesis and applicability of the proposed
method is demonstrated by two types of probes: rough and smoothened. The
accuracy of measuring Mean Squared (Angular) Displacements are also
demonstrated by using these 2 probes dispersed in 2 different solvents. The
presented 3D trackable colloids offer a high potential for wide range of
applications and studies, such as probing crystallization dynamics, phase
transitions and the effect of surface roughness on diffusion
Milk fatty acid profile related to energy balance in dairy cows
Milk fatty acid (FA) profile is a dynamic pattern influenced by lactational stage, energy balance and dietary composition. In the first part of this study, effects of the energy balance during the proceeding lactation [weeks 1-21 post partum (pp)] on milk FA profile of 30 dairy cows were evaluated under a constant feeding regimen. In the second part, effects of a negative energy balance (NEB) induced by feed restriction on milk FA profile were studied in 40 multiparous dairy cows (20 feed-restricted and 20 control). Feed restriction (energy balance of â63 MJ NEL/d, restriction of 49 % of energy requirements) lasted 3 weeks starting at around 100 days in milk. Milk FA profile changed markedly from week 1 pp up to week 12 pp and remained unchanged thereafter. The proportion of saturated FA (predominantly 10:0, 12:0, 14:0 and 16:0) increased from week 1 pp up to week 12 pp, whereas monounsaturated FA, predominantly the proportion of 18:1,9c decreased as NEB in early lactation became less severe. During the induced NEB, milk FA profile showed a similarly directed pattern as during the NEB in early lactation, although changes were less marked for most FA. Milk FA composition changed rapidly within one week after initiation of feed restriction and tended to adjust to the initial composition despite maintenance of a high NEB. C18:1,9c was increased significantly during the induced NEB indicating mobilization of a considerable amount of adipose tissue. Besides 18:1,9c, changes in saturated FA, monounsaturated FA, de-novo synthesized and preformed FA (sum of FA >C16) reflected energy status in dairy cows and indicated the NEB in early lactation as well as the induced NEB by feed restrictio
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