655 research outputs found
Vibrational origin of the fast relaxation processes in molecular glass-formers
We study the interaction of the relaxation processes with the density
fluctuations by molecular dynamics simulation of a flexible molecule model for
o-terphenyl (oTP) in the liquid and supercooled phases. We find evidence,
besides the structural relaxation, of a secondary vibrational relaxation whose
characteristic time, few ps, is slightly temperature dependent. This i)
confirms the result by Monaco et al. [Phys. Rev, E 62, 7595 (2000)] of the
vibrational nature of the fast relaxation observed in Brillouin Light
Scattering (BLS) experiments in oTP; and ii) poses a caveat on the
interpretation of the BLS spectra of molecular systems in terms of a purely
center of mass dynamics.Comment: RevTeX, 5 pages, 4 eps figure
Statistical-mechanical theory of ultrasonic absorption in molecular liquids
We present results of theoretical description of ultrasonic phenomena in
molecular liquids. In particular, we are interested in the development of
microscopical, i.e., statistical-mechanical framework capable to explain the
long living puzzle of the excess ultrasonic absorption in liquids. Typically,
ultrasonic wave in a liquid can be generated by applying the periodically
alternating external pressure with the angular frequency that corresponds to
the ultrasound. If the perturbation introduced by such process is weak - its
statistical-mechanical treatment can be done with the use of the linear
response theory. We treat the liquid as a system of interacting sites, so that
all the response/aftereffect functions as well as the energy dissipation and
generalized (wave-vector and frequency dependent) ultrasonic absorption
coefficient are obtained in terms of familiar site-site static and time
correlation functions such as static structure factors or intermediate
scattering functions. To express the site-site intermediate scattering
functions we refer to the site-site memory equations in the mode-coupling
approximation for the first-order memory kernels, while equilibrium properties
such as site-site static structure factors, direct and total correlation
functions are deduced from the integral equation theory of molecular liquids
known as RISM or one of its generalizations. All the formalism is phrased in a
general manner, hence the obtained results are expected to work for arbitrary
type of molecular liquid including simple, ionic, polar, and non-polar liquids.Comment: 14 pages, 1 eps-figure, RevTeX4-forma
Metallic Xenon, Molecular Condensates, and Superconductivity
A possibility of explaining the light absorption observed to occur under
pressure-induced xenon metallization as due to the transition to the
superconducting state is analyzed. The mechanism of the van der Waals bonding
is discussed.Comment: LaTeX 2.09 (RevTeX), 4 pages, 4 PostScript figures included in tex
Murder in Jerba : honour, shame and hospitality among Maltese in Ottoman Tunisia
Little is known about the sizeable Maltese communities developing along the southern and eastern shores of the Mediterranean in the mid-nineteenth century and the extent to which the migrants reproduced Maltese cultural traditions and practices overseas. This article considers this question through a microhistorical analysis of events culminating in the murder of a Maltese woman in the Ottoman Regency of Tunis in 1866. A close reading of transcripts from the interrogation of witnesses and the accused, all members of a Maltese community in Jerba reveals their shared cultural practices and beliefs surrounding the provision of hospitality, honour and shame. Viewed from this perspective, the curious responses of the witnesses to the murder of their compatriot become meaningful, and the crime is reframed as an honour killing.peer-reviewe
Coastal Ocean Forecasting: science foundation and user benefits
The advancement of Coastal Ocean Forecasting Systems (COFS) requires the support of continuous scientific progress addressing: (a) the primary mechanisms driving coastal circulation; (b) methods to achieve fully integrated coastal systems (observations and models), that are dynamically embedded in larger scale systems; and (c) methods to adequately represent air-sea and biophysical interactions. Issues of downscaling, data assimilation, atmosphere-wave-ocean couplings and ecosystem dynamics in the coastal ocean are discussed. These science topics are fundamental for successful COFS, which are connected to evolving downstream applications, dictated by the socioeconomic needs of rapidly increasing coastal populations
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Kitchens and PantriesâHelping or Hindering? The Perspectives of Emergency Food Users in Victoria, Australia
In high-income countries, people affected by food insecurity may seek out free/subsidized food from charities. Their perceptions of the food programs provided and preferences for alternative strategies are underresearched. The aim of this study was to develop an understanding of the usersâ experiences of food insecurity and gain evidence for effective responses in the future. Twelve semistructured interviews with a sample of users, who were also charity volunteers, were conducted in Victoria, Australia. A thematic analysis of the interview transcripts was undertaken. The results show that users have complex needs. Charities have both the capacity to hinder and help people maintain dignity, social inclusion, and health. Alternative community and policy food security strategies were proposed by interviewees. In the future, perspectives of affected community members must inform strategies that seek to improve peopleâs access to safe, nutritious, and affordable food. A human right to food framework is discussed as a mechanism to help realize food security in Australia
Quasi Harmonic Lattice Dynamics and Molecular Dynamics calculations for the Lennard-Jones solids
We present Molecular Dynamics (MD), Quasi Harmonic Lattice Dynamics (QHLD)
and Energy Minimization (EM) calculations for the crystal structure of Ne, Ar,
Kr and Xe as a function of pressure and temperature. New Lennard-Jones (LJ)
parameters are obtained for Ne, Kr and Xe to reproduce the experimental
pressure dependence of the density. We employ a simple method which combines
results of QHLD and MD calculations to achieve densities in good agreement with
experiment from 0 K to melting. Melting is discussed in connection with
intrinsic instability of the solid as given by the QHLD approximation. (See
http://www.fci.unibo.it/~valle for related papers)Comment: 7 pages, 5 figures, REVte
Iphigeniaâs sacrifice: generational historicity as a structure of feeling in times of austerity
Iphi, an unemployed actor in austerity-ridden Greece, imagines a theatre adaptation of a classic tragedy, Iphigenia at Aulis, in which the heroine is sacrificed on the altar of austerity by politicians. While writing her play-script, Iphi has a dream: she is taken to the sacrificial altar, not by politicians, but by her own parents, the generation who lived through the affluent years before austerity. Iphiâs generational-analogical thinking introduces a politically inspiring historicity, which offers insights into the accountability of austerity. It also allows us to reassess the notion of generations as a local category and an anthropological analytical construct. The article indicates the emergence of an as yet not fully articulated generational awarenessâa new structure of feelingâabout austerity, which is outlined here as it develops in an incipient form. I argue that the emerging generational historicity communicates a critical message, but also hides from view less visible inequalities
Brownian motion: a paradigm of soft matter and biological physics
This is a pedagogical introduction to Brownian motion on the occasion of the
100th anniversary of Einstein's 1905 paper on the subject. After briefly
reviewing Einstein's work in its contemporary context, we pursue some lines of
further developments and applications in soft condensed matter and biology.
Over the last century Brownian motion became promoted from an odd curiosity of
marginal scientific interest to a guiding theme pervading all of the modern
(live) sciences.Comment: 30 pages, revie
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