A Predator-Prey Model with an Application to Lake Victoria Fisheries

Greater complexity in renewable resource models is achieved by acknowledging that species interact through a predator-prey relationship in which both species are harvested. The price of greater complexity is that traditional concepts, such as maximum sustained yield (MSY), have to be revised dramatically. Moreover, having chosen greater complexity, fishery biologists and other researchers must choose an explicit value for each fish, a rate of exchange of one species for every other species. Policy makers and social scientists in Tanzania, Kenya, and Uganda with a keen interest in Lake Victoria fisheries regard the resource as a tool for furthering socioeconomic goals, such as foreign exchange earnings, employment for women, and nutrition. Comparative analysis allows policy makers to understand the consequences of choosing these goals in addition to economically efficient resource use. Foreign exchange earnings, employment for women, and healthy people are other goals promulgated by Tanzania, Kenya, and Uganda in the management of Lake Victoria Fisheries. The conflicts among social goals are evident in the bioeconomic predator-prey model: a goal favoring a particular species reduces the sustainable harvest of another species. Data from Kenya are used to estimate the population dynamics equations.predator-prey, bioeconomic model, Lake Victoria, Resource /Energy Economics and Policy, Q22, Q28,

Contingency power for small turboshaft engines using water injection into turbine cooling air

Because of one engine inoperative requirements, together with hot-gas reingestion and hot day, high altitude takeoff situations, power augmentation for multiengine rotorcraft has always been of critical interest. However, power augmentation using overtemperature at the turbine inlet will shorten turbine life unless a method of limiting thermal and mechanical stresses is found. A possible solution involves allowing the turbine inlet temperature to rise to augment power while injecting water into the turbine cooling air to limit hot-section metal temperatures. An experimental water injection device was installed in an engine and successfully tested. Although concern for unprotected subcomponents in the engine hot section prevented demonstration of the technique's maximum potential, it was still possible to demonstrate increases in power while maintaining nearly constant turbine rotor blade temperature

Values of sleep/wake, activity/rest, circadian rhythms, and fatigue prior to adjuvant breast cancer chemotherapy.

Fatigue is the most prevalent and distressing symptom experienced by patients receiving adjuvant chemotherapy for early stage breast cancer. Higher fatigue levels have been related to sleep maintenance problems and low daytime activity in patients who have received chemotherapy, but knowledge describing these relationships prior to chemotherapy is sparse. The Piper Integrated Fatigue Model guided this study, which describes sleep/wake, activity/rest, circadian rhythms, and fatigue and how they interrelate in women with Stage I, II, or IIIA breast cancer during the 48 hours prior to the first adjuvant chemotherapy treatment. The present report describes these variables in 130 females, mean age=51.4 years; the majority were married and employed. Subjective sleep was measured by the Pittsburgh Sleep Quality Index and fatigue was measured by the Piper Fatigue Scale. Wrist actigraphy was used to objectively measure sleep/wake, activity/rest, and circadian rhythms. Mean Pittsburgh Sleep Quality Index score was 6.73+/-3.4, indicating poor sleep. Objective sleep/wake results were within normal limits established for healthy individuals, except for the number and length of night awakenings. Objective activity/rest results were within normal limits except for low mean daytime activity. Circadian rhythm mesor was 132.3 (24.6) and amplitude was 97.2 (22.8). Mean Piper Fatigue Scale score was 2.56+/-2, with 72% reporting mild fatigue. There were significant relationships between subjective and objective sleep, but no consistent patterns. Higher total and subscale fatigue scores were correlated with most components of poorer subjective sleep quality (r=0.25-0.42, P\u3c or =0.005)

SIGMA: Bulletin of European statistics No 2-3 1994. Statistics of services

We present the fabrication and characterization of an aluminum transmon qubit on a silicon-on-insulator substrate. Key to the qubit fabrication is the use of an anhydrous hydrofluoric vapor process which selectively removes the lossy silicon oxide buried underneath the silicon device layer. For a 5.6 GHz qubit measured dispersively by a 7.1 GHz resonator, we find T_1 = 3.5 μs and T_2* = 2.2 μs. This process in principle permits the co-fabrication of silicon photonic and mechanical elements, providing a route towards chip-scale integration of electro-opto-mechanical transducers for quantum networking of superconducting microwave quantum circuits. The additional processing steps are compatible with established fabrication techniques for aluminum transmon qubits on silicon

H3K36 Methylation Promotes Longevity by Enhancing Transcriptional Fidelity

Epigenetic mechanisms, including histone post-translational modifications, control longevity in diverse organisms. Relatedly, loss of proper transcriptional regulation on a global scale is an emerging phenomenon of shortened life span, but the specific mechanisms linking these observations remain to be uncovered. Here, we describe a life span screen in Saccharomyces cerevisiae that is designed to identify amino acid residues of histones that regulate yeast replicative aging. Our results reveal that lack of sustained histone H3K36 methylation is commensurate with increased cryptic transcription in a subset of genes in old cells and with shorter life span. In contrast, deletion of the K36me2/3 demethylase Rph1 increases H3K36me3 within these genes, suppresses cryptic transcript initiation, and extends life span. We show that this aging phenomenon is conserved, as cryptic transcription also increases in old worms. We propose that epigenetic misregulation in aging cells leads to loss of transcriptional precision that is detrimental to life span, and, importantly, this acceleration in aging can be reversed by restoring transcriptional fidelity

M dwarfs: effective temperatures, radii and metallicities

We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a new technique which exploits the flux ratio in different bands as a proxy of both effective temperature and metallicity. Our temperature scale for late type dwarfs extends well below 3000 K (almost to the brown dwarf limit) and is supported by interferometric angular diameter measurements above 3000 K. Our metallicities are in excellent agreement (usually within 0.2 dex) with recent determinations via independent techniques. A subsample of cool M dwarfs with metallicity estimates based on hotter Hipparcos common proper-motion companions indicates our metallicities are also reliable below 3000 K, a temperature range unexplored until now. The high quality of our data allow us to identify a striking feature in the bolometric luminosity versus temperature plane, around the transition from K to M dwarfs. We have compared our sample of stars with theoretical models and conclude that this transition is due to an increase in the radii of the M dwarfs, a feature which is not reproduced by theoretical models.Comment: 26 pages, 14 figures. Accepted by MNRAS. Landscape table available online at http://users.utu.fi/luccas/MOITE

Resource utilization and costs before and after total joint arthroplasty

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to compare pre- and post-surgical healthcare costs in commercially insured total joint arthroplasty (TJA) patients with osteoarthritis (OA) in the United States (U.S.).</p> <p>Methods</p> <p>Using a large healthcare claims database, we identified patients over age 39 with hip or knee OA who underwent unilateral primary TJA (hip or knee) between 1/1/2006 and 9/30/2007. Utilization of healthcare services and costs were aggregated into three periods: 12 months "pre-surgery," 91 days "peri-operative," and 3 to 15 month "follow-up," Mean total pre-surgery costs were compared with follow-up costs using Wilcoxon signed-rank test.</p> <p>Results</p> <p>14,912 patients met inclusion criteria for the study. The mean total number of outpatient visits declined from pre-surgery to follow-up (18.0 visits vs 17.1), while the percentage of patients hospitalized increased (from 7.5% to 9.8%) (both <it>p </it>< 0.01). Mean total costs during the follow-up period were 18% higher than during pre-surgery ($11,043 vs.$9,632, <it>p </it>< 0.01), largely due to an increase in the costs of inpatient care associated with hospital readmissions ($3,300 vs.$1,817, p < 0.01). Pharmacotherapy costs were similar for both periods ($2013 [follow-up] vs.$1922 [pre-surgery], p = 0.33); outpatient care costs were slightly lower in the follow-up period ($4338 vs.$4571, <it>p </it>< 0.01). Mean total costs for the peri-operative period were $36,553.</p> <p>Conclusions</p> <p>Mean total utilization of outpatient healthcare services declined slightly in the first year following TJA (exclusive of the peri-operative period), while mean total healthcare costs increased during the same time period, largely due to increased costs associated with hospital readmissions. Further study is necessary to determine whether healthcare costs decrease in subsequent years.</p

Law professors want hearing, vote on Garland

Dear Senator Fischer and Senator Sasse, We write this as citizens, but we all teach at the University of Nebraska College of Law. We hold different political viewpoints and disagree frequentIy with each other on political and legal issues. As law professors, however, we share a deep commitment to the rule of law and an impartial judiciary. We therefore urge you to hold confirmation hearings and a vote on President Obama\u27s Supreme Court nominee, Chief Judge Merrick B. Garland