1,694 research outputs found
Quantum lattice models at intermediate temperatures
We analyze the free energy and construct the Gibbs-KMS states for a class of
quantum lattice systems, at low temperatures and when the interactions are
almost diagonal in a suitable basis. We study systems with continuous symmetry,
but our results are valid for discrete symmetry breaking only. Such phase
transitions occur at intermediate temperatures where the continuous symmetry is
not broken, while at very low temperature continuous symmetry breaking may
occur.Comment: 25 pages, 6 figure
Methods of Expressing Purpose in Romans, First Corinthians, Second Corinthians, Galatians, and Hebrews
The purpose of this paper is to investigate and compare the methods of expressing purpose in four letters written by the Apostle Paul and in the Epistle to the Hebrews. The four epistles of St. Paul which have been studied are the one to the Romans, both letters to the Corinthians, and the one to the Galatians. It is hoped that some light might be shed on the probability or improbability of the Pauline authorship of the Epistle to the Hebrews
3D gravity and non-linear cosmology
By the inclusion of an additional term, non-linear in the scalar curvature
, it is tested if dark energy could rise as a geometrical effect in 3D
gravitational formulations. We investigate a cosmological fluid obeying a
non-polytropic equation of state (the van der Waals equation) that is used to
construct the energy-momentum tensor of the sources, representing the
hypothetical inflaton in gravitational interaction with a matter contribution.
Following the evolution in time of the scale factor, its acceleration, and
the energy densities of constituents it is possible to construct the
description of an inflationary 3D universe, followed by a matter dominated era.
For later times it is verified that, under certain conditions, the non-linear
term in can generate the old 3D universe in accelerated expansion, where
the ordinary matter is represented by the barotropic limit of the van der Waals
constituent.Comment: 7 pages, to appear in Mod. Phys. Let
Non-linear terms in 2D cosmology
In this work we investigate the behavior of two-dimensional (2D) cosmological
models, starting with the Jackiw-Teitelboim (JT) theory of gravitation. A
geometrical term, non-linear in the scalar curvature , is added to the JT
dynamics to test if it could play the role of dark energy in a 2D expanding
universe. This formulation makes possible, first, the description of an early
(inflationary) 2D universe, when the van der Waals (vdW) equation of state is
used to construct the energy-momentum tensor of the gravitational sources.
Second, it is found that for later times the non-linear term in can
generate an old 2D universe in accelerated expansion, where an ordinary matter
dominated era evolves into a decelerated/accelerated transition, giving to the
dark energy effects a geometrical origin. The results emerge through numerical
analysis, following the evolution in time of the scale factor, its
acceleration, and the energy densities of constituents.Comment: tex file plus figures in two zipped files. To appear in Europhys.
Let
Micro-optic lens for data storage
A new type of microlens for data storage applications that has improved off-axis performance is described. The lens consists of a micro Fresnel pattern on a curved substrate. The radius of the substrate is equal to the focal length of the lens. If the pattern and substrate are thin, the combination satisfies the Abbe sine condition. Therefore, the lens is free of coma. We analyze a 0.5 numerical aperture, 0.50 mm focal length lens in detail. A 0.16 numerical aperture lens was fabricated holographically, and results are presented
A near-field scanning optical microscope for analysis of magneto-optic media
The design of a near-field scanning optical microscope (NSOM) is described. Applications to the study of magneto-optic media and domain detection are discussed
Prazosin + Naltrexone Decreases Alcohol Drinking More Effectively Than Does Either Drug Alone in P Rats with a Protracted History of Extensive Voluntary Alcohol Drinking, Dependence, and Multiple Withdrawals
Background
Prazosin (PRZ, an α1-adrenergic receptor antagonist) and naltrexone (NTX, a non-specific opioid receptor antagonist) each decrease alcohol drinking when administered to rats selectively-bred for high voluntary alcohol drinking (alcohol-preferring, or “P”), and the combination of PRZ+NTX decreases alcohol drinking more effectively than does either drug alone. Since drug responsiveness can depend on history of alcohol drinking and dependence, we investigated whether various schedules of PRZ and NTX administration, alone or in combination, are effective in decreasing alcohol drinking in male P rats with a history of protracted voluntary alcohol drinking, dependence and repeated withdrawals closely resembling human alcoholism.
Methods
Male P rats became alcohol-dependent during 1 year of ad libitum 24 h/day access to food, water and 20% alcohol with repetitive temporary alcohol withdrawals. Four sequential studies then addressed effects of oral PRZ (2 mg/kg) and NTX (10 mg/kg), alone or together, on alcohol drinking during: 1) daily alcohol access with daily drug treatment, 2) intermittent alcohol access with daily drug treatment, 3) intermittent alcohol access with occasional drug treatment, and 4) post-deprivation reinstatement of alcohol access.
Results
The combination of PRZ+NTX consistently suppressed alcohol drinking during daily or intermittent alcohol access conditions and when drug treatment was either daily or occasional. PRZ+NTX was consistently more effective than either drug alone. The reduction in alcohol drinking was not due to sedation, motor effects or malaise.
Conclusions
Both daily and “as-needed” treatment with PRZ+NTX are highly effective in suppressing daily, intermittent and post-deprivation alcohol drinking in male P rats with a protracted history of alcohol dependence and repeated withdrawals. This drug combination may be especially effective for treating individuals with long histories of heavy alcohol abuse, dependence and repeated relapse, as commonly encountered in clinical practice
Nonlocal Effects on the Magnetic Penetration Depth in d-wave Superconductors
We show that, under certain conditions, the low temperature behavior of the
magnetic penetration depth of a pure d-wave superconductor is
determined by nonlocal electrodynamics and, contrary to the general belief, the
deviation is proportional to T^2 and
not T. We predict that the dependence, due to
nonlocality, should be observable experimentally in nominally clean high-T_c
superconductors below a crossover temperature . Possible complications due to impurities, surface quality and
crystal axes orientation are discussed.Comment: REVTeX3.0; 4 pages, 1 EPS figure (included); Submitted to Phys. Rev.
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An informed thought experiment exploring the potential for a paradigm shift in aquatic food production
The Neolithic Revolution began c. 10000 years ago and is characterised by the
ultimate, near complete transition from hunting and gathering to agricultural
food production on land. The Neolithic Revolution is thought to have been
catalysed by a combination of local population pressure, cultural diffusion,
property rights and climate change. We undertake a thought experiment that
examines trends in these key hypothesised catalysts and patters of today to
explore whether society could be on a path towards another paradigm shift in
food production: away from hunting of wild fish towards a transition to mostly
fish farming. We find similar environmental and cultural pressures have driven
the rapid rise of aquaculture, during a period that has now been coined the
Blue Revolution, providing impetus for such a transition in coming decades to
centuries. We also highlight the interacting and often mutually reinforcing
impacts of 1)technological and scientific advancement, 2)environmental
awareness and collective action and 3)globalisation and trade influencing the
trajectory and momentum of the Blue Revolution. We present two qualitative
narratives that broadly fall within two future trajectories: 1)a ubiquitous
aquaculture transition and 20commercial aquaculture and fisheries coexistence.
This scenarios approach aims to encourage logical, forward thinking, and
innovative solutions to complex systems dynamics. Scenario-based thought
experiments are useful to explore large scale questions, increase the
accessibility to a wider readership and ideally catalyse discussion around
proactive governance mechanisms. We argue the future is not fixed and society
now has greater foresight and capacity to choose the workable balance between
fisheries sand aquaculture that supports economic, environmental, cultural and
social objectives through combined planning, policies and management
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