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

Long time motion of NLS solitary waves in a confining potential

We study the motion of solitary-wave solutions of a family of focusing generalized nonlinear Schroedinger equations with a confining, slowly varying external potential, $V(x)$. A Lyapunov-Schmidt decomposition of the solution combined with energy estimates allows us to control the motion of the solitary wave over a long, but finite, time interval. We show that the center of mass of the solitary wave follows a trajectory close to that of a Newtonian point particle in the external potential $V(x)$ over a long time interval.Comment: 42 pages, 2 figure

Investigation of the old Cumberland House trading post (FIMn-8) : an analysis of the artifact and faunal assemblages

The Old Cumberland House site (FIMn-8) is a fur trading post site located in the vicinity of the Cumberland House settlement in east central Saskatchewan. This site contains the remains of the first Hudson's Bay Company western inland trading post. In the fall of 1774, Samuel Hearne established this post on the southern shore of Cumberland Lake. This post remained in use until 1794 when operations were moved 1.5 km northwest to the location of the (New) Cumberland House fur trade post. Old Cumberland house was excavated during the field seasons of 1991, 1992, and 1994 in an effort to establish whether it was the true location of the Hudson's Bay Company post. This project was a joint effort between the Department of Anthropology and Archaeology at the University of Saskatchewan and the Cumberland House Historical Society. Funding was provided by the Access to Archaeology Program of the Department of Communications, the Cumberland House Development Corporation, and the Saskatchewan Heritage Foundation. Excavations at the Old Cumberland House site focused on existing features. The excavation of this site provides the opportunity for analysis of the physical layout of the first Hudson's Bay Company western inland trading post as no maps exist. Information obtained during excavation will be compared with historical textual documents. An in depth analysis of the Cumberland House journals provides a more complete picture of the structural and functional components of the post. The presence or absence of specific faunal and artifact materials in each area will help to deduce the function of each structure. Finally, an examination of faunal materials from the Old Cumberland House site and information from the Cumberland House journals will provide evidence to suggest that a diverse array of local resources was available to the occupants of Old Cumberland House

3D gravity and non-linear cosmology

By the inclusion of an additional term, non-linear in the scalar curvature $R$, 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 $R$ 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 $R$, 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 $R$ 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

The Effects of Long-Term Varenicline Administration on Ethanol and Sucrose Seeking and Self-Administration in Male P Rats

Background Varenicline, a partial agonist at α4β2 and full agonist at α7 nicotinic cholinergic receptors, is FDA-approved for treatment of smoking cessation and has been found to reduce alcohol craving in clinical populations. In rodents, varenicline decreases free-choice ethanol (EtOH) intake with somewhat mixed findings in operant paradigms that utilize a combined appetitive/consummatory response. Methods The present experiment utilized an operant paradigm that procedurally separates appetitive from consummatory responding and a “reward-blocking” approach (i.e., rats were able to consume EtOH during treatment) to better understand the efficacy of varenicline as a treatment for EtOH self-administration and subsequent EtOH seeking. Separate groups of EtOH- and sucrose-reinforced alcohol-preferring, male P rats experienced alternating cycles of vehicle (2-week cycles) and varenicline (0.3, 1.0, and 2.0 mg/kg self-administered in a gelatin preparation) treatment (3-week cycles) prior to daily sessions where a single lever press resulted in 20 minutes of reinforcer access. At the end of each cycle, a single extinction session assessed the seeking response in the absence of drug pretreatment. Results Varenicline dose dependently decreased EtOH intake. Sucrose intake was largely unaffected, with no overall treatment effects and only sporadic days where the medium and high dose differed from vehicle. Neither sucrose nor EtOH seeking was significantly decreased by varenicline, and there were no treatment effects on either lick or lever-press latency. Overall effect sizes were much greater for both drinking and seeking in the EtOH group as compared to the sucrose group. Conclusions Varenicline effectively attenuates EtOH self-administration during treatment, but the experience with EtOH consumption while varenicline is “on board” is not sufficient to alter subsequent EtOH seeking. The overall pattern of findings indicates that varenicline blocks the rewarding properties of EtOH while not substituting for EtOH, that the nonspecific effects on an alternate reinforcer are negligible, and that blood levels of varenicline need to be maintained in order for treatment to remain effective

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

Combining the α1-Adrenergic Receptor Antagonist, Prazosin, with the β-Adrenergic Receptor Antagonist, Propranolol, Reduces Alcohol Drinking More Effectively Than Either Drug Alone

Background Evidence suggests that activation of the noradrenergic system may contribute to alcohol drinking in animals and humans. Our previous studies demonstrated that blocking α1-adrenergic receptors with the antagonist, prazosin, decreased alcohol drinking in rats under various conditions. Since noradrenergic activation is also regulated by β-adrenergic receptors, we now examine the effects of the β-adrenergic receptor antagonist, propranolol, alone or in combination with prazosin, on alcohol drinking in rats selectively bred for high voluntary alcohol intake and alcohol preference (P line). Methods Two studies were conducted with male P rats. In study one, rats were allowed to become alcohol-dependent during 14 weeks of ad libitum access to food, water and 20% alcohol and the effect of propranolol (5–15 mg/kg, IP) and prazosin (1–2 mg/kg, IP) on alcohol intake during withdrawal were assessed. In study two, the effect of propranolol (5 mg/kg, IP) and prazosin (2 mg/kg, IP) on alcohol intake following prolonged imposed abstinence was assessed. Results Alcohol drinking following propranolol treatment was variable, but the combination of propranolol + prazosin consistently suppressed alcohol drinking during both alcohol withdrawal and following prolonged imposed abstinence, and the combination of these two drugs was more effective than was treatment with either drug alone. Conclusions Treatment with prazosin + propranolol, or a combination of other centrally active α1- and β-adrenergic receptor antagonists, may assist in preventing alcohol relapse in some individuals

Social evaluation at a distance – facets of stereotype content about student groups in higher distance education

In the academic domain, belonging to a negatively stereotyped group can impair performance and peer relationships. In higher distance education, stereotypes may be particularly influential as face-to-face contact is limited and non-traditional students who are at risk of being stereotyped are overrepresented. Still, research on stereotypes in higher distance education is sparse. The current research addresses this gap by investigating the Big Two of social perception (warmth, competence) and subordinate facets (friendliness, morality, assertiveness, ability, conscientiousness) in the context of higher distance education. It tests a) how well models with warmth/competence or the facets fit the data, b) whether stereotypes in higher distance education depend on the student group, and c) how the Big Two and subordinate facets predict intergroup emotions and behavioral intentions in higher distance education. An online survey with N = 626 students (74% female) of a large distance university showed that a measurement model with four facets (i.e., friendliness, morality, ability, conscientiousness) reveals adequate model fit for 12 student groups. Perceived stereotypes were positive for female students, older students, and students with children. However, migrant as well as younger students were perceived negatively. Across groups, stereotype content facets predicted intergroup emotions and behavioral intentions of facilitation or harm. Implications for the influence of negative stereotypes in higher distance education are discussed