Classical Lagrangian Model of the Pauli Principle

A classical Lagrangian model of the Pauli potential is introduced. It is shown that the kinematic kinetic energy ($\sum \frac{1}{2} m v^2$) in the model approximately reproduces the energy of a free Fermi gas at low temperatures and at densities relevant in nuclear collisions with moderate beam energies. Differences between canonical and kinematic quantities are pointed out. The Pauli potential can be used in transport simulations.Comment: Latex, 8 pages, 3 figures available on request from the authors, KSUCNR-012-9

Listening to music at home and at school

This study investigated the differences between the functions of music listening at home and at school, and the potential effects of age and nationality on these differences. 120 participants completed an individual structured interview schedule, which consisted of ten open-ended questions. These covered the role of music listening in young people's leisure interests as a whole, and more speci®c aspects of listening at home and at school. Sixty participants were from schools in the UK, and sixty from schools in Portugal: within each nationality group, thirty were aged 9±10 years and thirty aged 13±14 years. The ®ndings showed that music listening was an important leisure activity, especially for the older children, and that most children showed moderate positive attitudes towards school music. Home music listening and school music ful®lled different functions: participants reported that home listening was linked with enjoyment, emotional mood and social relationships, whereas school music was associated with motivation for learning and being active, and particular lesson content. There were few clear-cut national differences, and music was generally undervalued in both countries.info:eu-repo/semantics/publishedVersio

Interpersonal Influences on Children's Emotional Responses to New Age Music

This study investigated the effects of interpersonal context and age on children's emotional responses to new age music. One hundred and twenty participants aged 9-10 and 13-14 years listened to four excerpts either alone, or in groups of three. Immediately after listening, they rated the emotions aroused by the excerpts on eight five point-scales based on a circumplex model which conceives of four quadrants of emotional response: positive/negative affect, and high/low arousal. The results showed that participants gave significantly higher ratings on four of the eight scales when listening in groups rather than when listening alone, and that the younger children gave significantly higher ratings on positive emotional states (relaxed, excited, energetic) and liking, whereas the older children gave significantly higher ratings on negative emotions (irritated, bored). These findings suggest the influence of both social and developmental factors upon children 's emotional responses to music; namely group effects, and younger children 's higher tolerance for unfamiliar styles.info:eu-repo/semantics/publishedVersio

Children"s Modes of Listening to Music at Home and at School

This study investigated how children listen to music, by examining relationships different modes of listening and different contexts, home and school. It also looked tal and cultural perspectives, by comparing children from different age levels and The 120 participants were British and Portuguese children aged 9-10 years, attending schools, and 13-14 years, attending secondary schools. Children responded interview with open-ended questions, concerning their modes of listening to music at school. Findings showed that children's modes of listening imply various levels emotional involvement with music, and depend on the context, which may be related junctions of music. At home, few children listened to music as a main activity. listening and performing (singing, dancing), or accompanying a variety of non-(studying, playing games). At school, children listened to music often while doing ties (analysis, performing), moderately as a main activity, but rarely while doing activities. There were no relevant national differences, and age differences resulted specific teaching strategies at each school level.info:eu-repo/semantics/publishedVersio

Non-local fluctuation correlations in active gels

Many active materials and biological systems are driven far from equilibrium by embedded agents that spontaneously generate forces and distort the surrounding material. Probing and characterizing these athermal fluctuations is essential for understanding the properties and behaviors of such systems. Here we present a mathematical procedure to estimate the local action of force-generating agents from the observed fluctuating displacement fields. The active agents are modeled as oriented force dipoles or isotropic compression foci, and the matrix on which they act is assumed to be either a compressible elastic continuum or a coupled network-solvent system. Correlations at a single point and between points separated by an arbitrary distance are obtained, giving a total of three independent fluctuation modes that can be tested with microrheology experiments. Since oriented dipoles and isotropic compression foci give different contributions to these fluctuation modes, ratiometric analysis allows us characterize the force generators. We also predict and experimentally find a high-frequency ballistic regime, arising from individual force generating events in the form of the slow build-up of stress followed by rapid but finite decay. Finally, we provide a quantitative statistical model to estimate the mean filament tension from these athermal fluctuations, which leads to stiffening of active networks.Comment: 12 pages, 7 figures; some clarifications and ammended figure notation

Force generation in small ensembles of Brownian motors

The motility of certain gram-negative bacteria is mediated by retraction of type IV pili surface filaments, which are essential for infectivity. The retraction is powered by a strong molecular motor protein, PilT, producing very high forces that can exceed 150 pN. The molecular details of the motor mechanism are still largely unknown, while other features have been identified, such as the ring-shaped protein structure of the PilT motor. The surprisingly high forces generated by the PilT system motivate a model investigation of the generation of large forces in molecular motors. We propose a simple model, involving a small ensemble of motor subunits interacting through the deformations on a circular backbone with finite stiffness. The model describes the motor subunits in terms of diffusing particles in an asymmetric, time-dependent binding potential (flashing ratchet potential), roughly corresponding to the ATP hydrolysis cycle. We compute force-velocity relations in a subset of the parameter space and explore how the maximum force (stall force) is determined by stiffness, binding strength, ensemble size, and degree of asymmetry. We identify two qualitatively different regimes of operation depending on the relation between ensemble size and asymmetry. In the transition between these two regimes, the stall force depends nonlinearly on the number of motor subunits. Compared to its constituents without interactions, we find higher efficiency and qualitatively different force-velocity relations. The model captures several of the qualitative features obtained in experiments on pilus retraction forces, such as roughly constant velocity at low applied forces and insensitivity in the stall force to changes in the ATP concentration.Comment: RevTex 9 pages, 4 figures. Revised version, new subsections in Sec. III, removed typo

Some observations on the renormalization of membrane rigidity by long-range interactions

We consider the renormalization of the bending and Gaussian rigidity of model membranes induced by long-range interactions between the components making up the membrane. In particular we analyze the effect of a finite membrane thickness on the renormalization of the bending and Gaussian rigidity by long-range interactions. Particular attention is paid to the case where the interactions are of a van der Waals type.Comment: 11 pages RexTex, no figure

Monotherapy with major antihypertensive drug classes and risk of hospital admissions for mood disorders

Major depressive and bipolar disorders predispose to atherosclerosis, and there is accruing data from animal model, epidemiological, and genomic studies that commonly used antihypertensive drugs may have a role in the pathogenesis or course of mood disorders. In this study, we propose to determine whether antihypertensive drugs have an impact on mood disorders through the analysis of patients on monotherapy with different classes of antihypertensive drugs from a large hospital database of 525 046 patients with follow-up for 5 years. There were 144 066 eligible patients fulfilling the inclusion criteria: age 40 to 80 years old at time of antihypertensive prescription and medication exposure >90 days. The burden of comorbidity assessed by Charlson and Elixhauser scores showed an independent linear association with mood disorder diagnosis. The median time to hospital admission with mood disorder was 847 days for the 299 admissions (641 685 person-years of follow-up). Patients on angiotensin-converting enzyme inhibitors or angiotensin receptor blockers had the lowest risk for mood disorder admissions, and compared with this group, those on β-blockers (hazard ratio=2.11; [95% confidence interval, 1.12–3.98]; P=0.02) and calcium antagonists (2.28 [95% confidence interval, 1.13–4.58]; P=0.02) showed higher risk, whereas those on no antihypertensives (1.63 [95% confidence interval, 0.94–2.82]; P=0.08) and thiazide diuretics (1.56 [95% confidence interval, 0.65–3.73]; P=0.32) showed no significant difference. Overall, our exploratory findings suggest possible differential effects of antihypertensive medications on mood that merits further study: calcium antagonists and β-blockers may be associated with increased risk, whereas angiotensin-converting enzyme inhibitors and angiotensin receptor blockers may be associated with a decreased risk of mood disorders

The thermal Casimir effect in lipid bilayer tubules

We calculate the thermal Casimir effect for a dielectric tube of radius $R$ and thickness delta formed from a membrane in water. The method uses a field-theoretic approach in the grand canonical ensemble. The leading contribution to the Casimir free energy behaves as -k_BTL kappa_C/R giving rise to an attractive force which tends to contract the tube. We find that kappa_C ~ 0.3 for the case of typical lipid membrane t-tubules. We conclude that except in the case of a very soft membrane this force is insufficient to stabilize such tubes against the bending stress which tends to increase the radius.Comment: 4 pages no figures RevTe

Specific Functions of BIG1 and BIG2 in Endomembrane Organization

Background: Transport of molecules from one subcellular compartment to another involves the recruitment of cytosolic coat protein complexes to a donor membrane to concentrate cargo, deform the membrane and ultimately to form an independent carrier. Small-GTP-binding proteins of the Arf family are central to many membrane trafficking events. Arfs are activated by guanine nucleotide exchange factors (GEFs) which results in their recruitment to membranes and subsequent engagement with Arf-effectors, many of which are coat proteins. Among the human BFA-sensitive large Arf-GEFs, the function of the two closely related BIG1 and BIG2 is still not clear, and recent studies have raised the question of functional redundancy between the two proteins. Methodology/Principal Findings: Here we have used small-interfering RNA on human cells and a combination of fixed and live-cell imaging to investigate the differential functions of BIG1 and BIG2 in endomembrane organization and function. Importantly, in this direct comparative study, we show discrete functions for BIG1 and BIG2. Our results show that depletion of BIG2 but not of BIG1 induces a tubulation of the recycling endosomal compartment, consistent with a specific role for BIG2 here. In contrast, suppression of BIG1 induces the formation of Golgi mini-stacks still polarized and functional in terms of cargo export. Conclusions: A key finding from our work is that suppression of BIG1 expression results in a fragmentation of the Golg