Status of the PICASSO Project

The Picasso project is a dark matter search experiment based on the superheated droplet technique. Preliminary runs performed at the Picasso Lab in Montreal have showed the suitability of this detection technique to the search for weakly interacting cold dark matter particles. In July 2002, a new phase of the project started. A batch of six 1-liter detectors with an active mass of approximately 40g was installed in a gallery of the SNO observatory in Sudbury, Ontario, Canada at a depth of 6,800 feet (2,070m). We give a status report on the new experimental setup, data analysis, and preliminary limits on spin-dependent neutralino interaction cross section.Comment: 3 pages, 2 figures. To appear in the Proceedings of the TAUP 2003 conference, 5-9 September, 2003, University of Washington, Seattle, US

Evidence of selection for resistance to paralytic shellfish toxins during the early life history of soft-shell clam (Mya arenaria) populations

Abstract This study identifies early, postmetamorphic soft-shell clams, Mya arenaria, as the life-history stage most susceptible to effects of blooms of paralytic shellfish poisoning (PSP) toxin-producing Alexandrium spp. Laboratory experiments used progeny from predominantly susceptible (naïve) or resistant (annually exposed) NW Atlantic populations. Growth and survival of toxified veliger larvae did not differ from those fed nontoxic algae. In contrast, postlarvae (4-12-mm shell length) from both populations exposed to a highly toxic Alexandrium tamarense isolate (, 100 cells mL 21 , 64-69 pg saxitoxin equivalents [STXeq] cell 21 ) suffered burrowing incapacitation, toxin accumulation, and mortalities within 1 week of toxin exposure. These effects were greater and occurred sooner in the naïve population. Short-term toxification in the laboratory caused a significant shift in the genotypic composition of this population, determined with a molecular marker for sodium-channel resistance. Clams with the sensitive genotype were selectively eliminated relative to resistant or heterozygote clams. Ingestion of toxic cells (too large for larval capture) is thus required to elicit toxic effects. Exposure to mixed, toxic, and nontoxic algal suspensions demonstrated that adverse effects to fitness (survival and growth) were dose-dependent, occurring only at $ 50 cells mL 21 of the isolate used (PR18b). Paralysis and thus increased predatory risk occurred even at 10 cells mL 21 . Postlarvae , 12 mm, which can co-occur with red tides throughout the Atlantic range of M. arenaria, were more susceptible to PSP than large (. 30 mm) juveniles. Natural selection for resistance in Atlantic populations will thus vary latitudinally with the timing, duration, and intensity of toxic blooms

A Model of Vertical Oligopolistic Competition

This paper develops a model of successive oligopolies with endogenous market entry, allowing for varying degrees of product differentiation and entry costs in both markets. Our analysis shows that the downstream conditions dominate the overall profitability of the two-tier structure while the upstream conditions mainly affect the distribution of profits. We compare the welfare effects of upstream versus downstream deregulation policies and show that the impact of deregulation may be overvalued when ignoring feedback effects from the other market. Furthermore, we analyze how different forms of vertical restraints influence the endogenous market structure and show when they are welfare enhancing

Women We Loved: Paradoxes of public and private in the biographical television drama

Broadcast to critical acclaim and relatively large audiences for its niche channel, the Women We Loved season consisted of biographical dramatisations of three prominent female figures of 20th-century British culture. These dramas shared in common narratives that centre on the two aspects of ‘the public’ and ‘the private’: the tension between public career and personal life and the discrepancy between celebrity persona and private individual. Combining theoretical insights from feminist studies of biography with close textual analysis, this article analyses how performance, aesthetics and narrative express the ambivalent placement of their protagonists between public and private spheres

Ordering of droplets and light scattering in polymer dispersed liquid crystal films

We study the effects of droplet ordering in initial optical transmittance through polymer dispersed liquid crystal (PDLC) films prepared in the presence of an electrical field. The experimental data are interpreted by using a theoretical approach to light scattering in PDLC films that explicitly relates optical transmittance and the order parameters characterizing both the orientational structures inside bipolar droplets and orientational distribution of the droplets. The theory relies on the Rayleigh-Gans approximation and uses the Percus-Yevick approximation to take into account the effects due to droplet positional correlations.Comment: revtex4, 18 pages, 8 figure

An Investigation of sexuality and life satisfaction of institutionalized aged

One concern of this study is sexuality among the aged, since every person, regardless of age, is a sexual being. Society, however, has been slow to recognize this fact and has not accepted sexual activity among the aged. Along with the lack of social sanctioning, elderly persons are very susceptible to the myriad of myths, half-truths, misinformation, and incomplete data which affect their attitudes toward sexuality. Furthermore, older persons are susceptible to negative stereotypes of themselves as sexual beings. However, the effect of actual sexual activity upon overall life satisfaction among the aged has yet to be determined. Because there has been no empirical evidence concerning this, the degree of relationship between sexual activity and life satisfaction remains unknown. Since human beings remain sexual throughout life, and a large proportion of the elderly are institutionalized, this study will focus attention on the relationship between life satisfaction and sexuality among the institutionalized aged. It is important for social workers to explore these concepts, as empirically validated knowledge can be used as guidelines for professional values and practice

The Supercooling of a Nematic Liquid Crystal

We investigate the supercooling of a nematic liquid crystal using fluctuating non-linear hydrodynamic equations. The Martin-Siggia-Rose formalism is used to calculate renormalized transport coefficients to one-loop order. Similar theories for isotropic liquids have shown substantial increases of the viscosities as the liquid is supercooled or compressed due to feedback from the density fluctuations which are freezing. We find similar results here for the longitudinal and various shear viscosities of the nematic. However, the two viscosities associated with the nematic director motion do not grow in any dramatic way; i.e.\ there is no apparent freezing of the director modes within this hydrodynamic formalism. Instead a glassy state of the nematic may arise from a ``random anisotropy" coupling of the director to the frozen density.Comment: Late

Topological Defects and Interactions in Nematic Emulsions

Inverse nematic emulsions in which surfactant-coated water droplets are dispersed in a nematic host fluid have distinctive properties that set them apart from dispersions of two isotropic fluids or of nematic droplets in an isotropic fluid. We present a comprehensive theoretical study of the distortions produced in the nematic host by the dispersed droplets and of solvent mediated dipolar interactions between droplets that lead to their experimentally observed chaining. A single droplet in a nematic host acts like a macroscopic hedgehog defect. Global boundary conditions force the nucleation of compensating topological defects in the nematic host. Using variational techniques, we show that in the lowest energy configuration, a single water droplet draws a single hedgehog out of the nematic host to form a tightly bound dipole. Configurations in which the water droplet is encircled by a disclination ring have higher energy. The droplet-dipole induces distortions in the nematic host that lead to an effective dipole-dipole interaction between droplets and hence to chaining.Comment: 17 double column pages prepared by RevTex, 15 eps figures included in text, 2 gif figures for Fig. 1