An assessment of scup (Stenotomus chrysops) and black sea bass (Centropristas striata) discards in the directed otter trawl fisheries in the Mid-Atlantic Bight

This study was undertaken to re-assess the level of scup (Stenotomus chrysops) discards by weight and to evaluate the effect of various codend mesh sizes on the level of scup discards in the winter-trawl scup fishery. Scup discards were high in directed scup tows regardless of codend mesh — typically one to five times the weight of landings. The weight of scup discards in the present study did not differ significantly from that recorded in scup-targeted tows in the NMFS observer database. Most discards were required as such by the 22.86 cm TL (total length) fish-size limit for catches. Mesh sizes ≤12.7 cm, including the current legal mesh size (11.43 cm) did not adequately filter out scup smaller than 22.86 cm. The median length of scup discards was about 19.83 cm TL. Lowering the legal size for scup from 22.86 to 19.83 cm TL would greatly reduce discard mortality. Scup discards were a small fraction (0.4%) of black sea bass (Centropristis striata) landings in blacksea-bass−targeted tows. The black sea bass fishery is currently regulated under the small-mesh fishery gearrestricted area plan in which fishing is prohibited in some areas to reduce scup mortality. Our study found no evidence to support the efficacy of this management approach. The expectations that discarding would increase disproportionately as the trip limit (limit [in kilograms] on catch for a species) was reached towards the end of the trip and that discards would increase when the trip limit was reduced from 4536 kg to 454 kg at the end of the directed fishing season were not supported. Trip limits did not significantly affect discard mortality

Crystal Structure and Magnetism of the Linear-Chain Copper Oxides Sr5Pb3-xBixCuO12

The title quasi-1D copper oxides (0=< x =<0.4) were investigated by neutron diffraction and magnetic susceptibility studies. Polyhedral CuO4 units in the compounds were found to comprise linear-chains at inter-chain distance of approximately 10 A. The parent chain compound (x = 0), however, shows less anisotropic magnetic behavior above 2 K, although it is of substantially antiferromagnetic (mu_{eff}= 1.85 mu_{B} and Theta_{W} = -46.4 K) spin-chain system. A magnetic cusp gradually appears at about 100 K in T vs chi with the Bi substitution. The cusp (x = 0.4) is fairly characterized by and therefore suggests the spin gap nature at Delta/k_{B} ~ 80 K. The chain compounds hold electrically insulating in the composition range.Comment: To be published in PR

Proportion Regulation in Globally Coupled Nonlinear Systems

As a model of proportion regulation in differentiation process of biological system, globally coupled activator-inhibitor systems are studied. Formation and destabilization of one and two cluster state are predicted analytically. Numerical simulations show that the proportion of units of clusters is chosen within a finite range and it is selected depend on the initial condition.Comment: 11 pages (revtex format) and 5 figures (PostScript)

Exploring online health seeking's potential via social search

Online Health Seeking (OHS) is widespread and widely studied, but its ideal fit in healthcare is still unclear. OHS is seemingly emblematic of patient self-interest and control and is an intuitive fit with the tenets of patient-centered care (PCC). Researchers have made only a few attempts to evidence or leverage this connection, focusing instead on describing the figures and typical characteristics of OHS. Finding, consuming and sharing online health and wellness information is one of the common online activities, and consumers are generally satisfied with their results despite using simple and error-prone search strategies. Physicians are interested in their patients' OHS, but for a variety of constraints including time, compensation and traditional roles in medicine, most patient OHS goes unshared with doctors. Healthcare facilitators, a relatively new class of health professional that works to bridge the gap between their client's health and personal life, may be an ideal partner for patients in OHS. In this dissertation I share my investigation of the OHS-PCC connection, presenting a case study of a type of healthcare facilitator that has embraced OHS. By studying OHS, I was also able to contribute to the collaborative information seeking (CIS) community. CIS theory and social search tools have pointed to social factors that can influence the entire process of information seeking. In this dissertation I argue that nearly any social search design can be seen as situated or embedded in a unique socio-environmental context. I suggest that social search tools can be used as probes to understand the environment, and that interactions with a search tool can illustrate phenomena far beyond direct search motivations and goals. I also hypothesize that social search field studies can produce changes in their environment, producing changes in user relationships outside of the experimental search system. My study of OHS is an opportunity to test these hypotheses by creating a collaborative search tool that seeks to use OHS as a tool to improve patient-provider relationships. In this dissertation I present the results of a series of field studies at a local clinic that centers on a unique form of health facilitator. Drawing on several formative investigations and related work I synthesize design guidelines for a collaborative OHS tool and describe Snack, a collaborative search tool for OHS customized to my field site. I also present results from Snack's field study and an analysis of email messages between advisors and clients at the clinic. My results show that these health facilitators embraced OHS as a tool to guide and connect with their clients, but fell from this practice after a change at their clinic. After analyzing these results I discuss what makes health facilitators good OHS partners and cover implications for future OHS-based interventions. I also report the positive connections I found between OHS and other quality of care indicators like patient-centered care and the Multidimensional Health Locus of Control. Finally, I consider social search's utility as a probe and intervention in light of my results.Ph.D

Renormalization group and other calculations for the one‐dimensional spin‐1/2 dimerized Heisenberg antiferromagnet

A zero-temperature renormalization group (RG) approach is applied to the one-dimensional, spin-1/2 anti ferromagnetic Heisenberg dimerized (alternating) chain. Specifically, the ground state energy and lowest-lying spectral excitations are examined. The calculation indicates the existence of a gap in the spectrum of the dimerized chain which vanishes only in the limit of a uniform spin chain in contrast to a recent Green\u27s function approach. The RG results are in reasonable agreement with numerical extrapolations on the exact eigenvalue spectrum of finite chains of up to 12 spins. Both methods are compared with several other approximate treatments of the Heisenberg system. and tested by comparison with exact results for the spin-1/2 XY dimerized chain