Distributed Adaptive Algorithms for Optimal Opportunistic Medium Access

We examine threshold-based transmission strategies for distributed opportunistic medium access in a scenario with fairly general probabilistic interference conditions. Specifically, collisions between concurrent transmissions are governed by arbitrary probabilities, allowing for a form of channel capture and covering binary interference constraints as an important special case. We address the problem of setting the threshold values so as to optimize the aggregate throughput utility of the various users, and particularly focus on a weighted logarithmic throughput utility function (Proportional Fairness). We provide an adaptive algorithm for finding the optimal threshold values in a distributed fashion, and rigorously establish the convergence of the proposed algorithm under mild statistical assumptions. Moreover, we discuss how the algorithm may be adapted to achieve packet-level stability with only limited exchange of queue length information among the various users. We also conduct extensive numerical experiments to corroborate the theoretical convergence results.14 page(s

Alteraciones a los Entornos de Permafrost Inducidas por el Cambio Climático

Permafrost environments currently cover approximately twenty-five percent of the Northern Hemisphere. However current empirical and theoretical evidence indicates that much of the existing permafrost is in thermal imbalance to the warming that has occurred over the last 150 years. Long-term increases of temperature in the polar regions has already led to a thickening of the active layer and the gaseous release of the once sequestered carbon and methane tundra stores; an event which is likely to amplify the changes foreseen and experienced in natural and human environments. Permafrost degradation has resulted in the complete restructuring of ecosystems and geomorphological and hydrological patterns and processes. Such changes have led to extensive thawing, removal of discontinuous permafrost and the growth of thermokarst. Collectively, all these climatic-induced alterations in the structure of permafrost environments has had a detrimental effect on wildlife populations, human settlement and infrastructure. The former has seen a transition from terrestrial to aquatic ecosystems whilst damage to the latter has led to some areas being officially classed as natural hazard zones. Therefore research and corresponding action must be undertaken at those locations where sequestered carbon is being released in sufficient quantities to be of concern to the wellbeing of the entire planet. Resumen Los entornos de permafrost actualmente cubren aproximadamente el veinticinco por ciento del hemisferio norte. Sin embargo, la evidencia empírica y teórica actual indica que gran parte del permafrost existente está en desequilibrio térmico por el calentamiento que se ha producido en los últimos 150 años. Los aumentos de la temperatura a largo plazo en las regiones polares ya han dado lugar a un engrosamiento de la capa activa y a la liberación gaseosa de los depósitos de carbono y el metano alguna vez secuestrados en la tundra; un evento que es probable que amplifique los cambios previstos y experimentados por los entornos naturales y humanos. La degradación del permafrost se ha traducido en la reestructuración completa de los ecosistemas y de los patrones y procesos geomorfológicos e hidrológicos. Tales cambios han conducido a un extenso descongelamiento, la eliminación del permafrost discontinuo y al crecimiento de termokarst. En conjunto, todas estas alteraciones climáticamente inducidas en la estructura de los ambientes de permafrost han tenido un efecto perjudicial sobre las poblaciones de la vida silvestre, los asentamientos humanos y la infraestructura. Las primeras formaciones han visto una transición de ecosistemas terrestre a acuáticos, mientras que el daño a estos últimos ha dado lugar a que algunas áreas sean clasificadas oficialmente como zonas de peligros naturales. Por lo tanto, la investigación y las acciones correspondientes deben llevarse a cabo en los lugares donde se está liberando el carbono secuestrado en cantidades suficientes como para ser motivo de preocupación para el bienestar de todo el planeta

Spontaneous and stimulated emission tuning characteristics of a Josephson junction in a microcavity

We have investigated theoretically the tuning characteristics of a Josephson junction within a microcavity for one-photon spontaneous emission and for one-photon and two-photon stimulated emission. For spontaneous emission, we have established the linear relationship between the magnetic induction and the voltage needed to tune the system to emit at resonant frequencies. For stimulated emission, we have found an oscillatory dependence of the emission rate on the initial Cooper pair phase difference and the phase of the applied field. Under specific conditions, we have also calculated the values of the applied radiation amplitude for the first few emission maxima of the system and for the first five junction-cavity resonances for each process. Since the emission of photons can be controlled, it may be possible to use such a system to produce photons on demand. Such sources will have applications in the fields of quantum cryptography, communications and computation

Beside the Sunset Trail

Illustration of trail that leads to house; Photograph of Guy Lombardohttps://scholarsjunction.msstate.edu/cht-sheet-music/9020/thumbnail.jp

Prospectus, January 18, 1974

VOTE ENDS IN TIE: SPARKS, WYLIE IN SPECIAL RUNOFF; Both Amendments Passed By Voters; Bob Waldon Wins Vice-Presidency; Sparks Defeats Wylie For StuGo President; SARP Awards Worth $1350; Energy Crisis Discussion Held At Parkland; Gwendolyn Brooks to Appear On Woman\u27s Day; Musical Coming; The Short Circuit; Cruisin\u27 \u2774: The Energy Crisis, Inflation; Prospectus In Perspectice; Letter To Editor; HEW Financial Aids Available; Inclement Weather Policies And Procedures; SIU\u27s Transfer Day To Be Feb. 2; Authorization To Issue Parking Tickets Granted; A Column By And For Women; Growing Up Female ; Nursing School Accredited For Four More Years; \u27Women\u27s Work, Women\u27s Way\u27 To Be Theme Of Jan. 22 Woman\u27s Day; Behind the Books; 50 Hour Documentary The History of Rock & Roll To Be Broadcasted On WLRW; Education: How Practical?; Oregon High School Students Earn Credit In National Guard; Mutt and Mortie; Bio 210 Relates To Earth Day ; Con Men Abound In \u27The Sting\u27; Rules For Safe Winter Driving; MTD Seeks To Serve P/C Better; Fuel Saver Of The State Of Illinois; Bus Survey; Classified Ads; Variety of Tests Available at Parkland Testing Center; Snow Days To Be Made Up In Feb.; Monday\u27s Coach; \u27Super Sunday\u27 Belongs To Miami; Bowling Bulletin Board; Pep Buses; Basketball and Volleyball Are IM Winter Sports; Snowfall Cancels Wrestling Meets; Attention Vets!; Bouncing Bob\u27s Basketball Bonanza; Cobras Even Conference Record At 1-1; Cobra Cager Profiles; Spring Pre-Registration Open January 22 Thru 31; Callboard; Parkland Events; Gardening Class Offered Spring Quarter at P/C; Attention Winter Quarter Graduateshttps://spark.parkland.edu/prospectus_1974/1022/thumbnail.jp

Prospectus, February 11, 1974

EFFECTIVE MARCH 11…PROSPECTUS TO GO WEEKLY; Publication Board Passes All Resolutions At Feb. 14 Meeting; Conveniamus 74 To Be Out May 1; Parkland Enters NIU Meet; Hulsizer Resigns; Prospectus In Perspective; Cruisin\u27 \u2774; The Short Circuit; Parkland Security Force Eligibility Examination; Old FBI Men Don\u27t Die, They Just...; Final Examination Schedule Winter Quarter, 1973-1974; Women Teachers Win Maternity Rights On Supreme Court Ruling; Financial Report; County Clerk Bing: Obey The Laws ; Behind The Books; Bookstore Renovations For Students; If You\u27re Neurotic.....\u27The Exorcist\u27 Great Horror Film; Three Sisters: Into The Depths; Kipnis: Angles Of Vision; Academic Calendar Committee\u27s Report; Gekko Lizard Gets The Silent Treatment At P/C; David Bromberg Provides Good Times; Musical Still In Question At P/C; What Your Gov\u27t Didn\u27t Do For You; A Column By And For Women: Waiting For The Equal Rights Amendment; Classified Ads; Two Gardening Classes Offered; 14 Days Of Sunshine, Friends And Surfing; Night Students\u27 Registration Set; NSS FNS To Sponsor Chicago College Day; Monday\u27s Coach; Cobra Cager; Cobras Dominated By Lake Land; Wrestlers In State Meet Today; Blood Freezing Helps Endurance; Regional Game Tournament; Table Tennis; Chicago Bulls; Canoe Trip; Basketball Team; Biking, Tennis, And Golf Are Coming In Spring; Jackson Sidelined With Broken Foot At Western Illinois; Bouncing Bob\u27s Basketball Bonanza; Bowling Bulletin Board; Callboard; Students Paid For Drinking; Parkland Events; No Shows To Increase; Abbie Loses 1st Cocaine Trial; Miss California Contest Stopped By 17-Year-Old; Bowling Champshttps://spark.parkland.edu/prospectus_1974/1020/thumbnail.jp

Access and utilisation of primary health care services comparing urban and rural areas of Riyadh Providence, Kingdom of Saudi Arabia

The Kingdom of Saudi Arabia (KSA) has seen an increase in chronic diseases. International evidence suggests that early intervention is the best approach to reduce the burden of chronic disease. However, the limited research available suggests that health care access remains unequal, with rural populations having the poorest access to and utilisation of primary health care centres and, consequently, the poorest health outcomes. This study aimed to examine the factors influencing the access to and utilisation of primary health care centres in urban and rural areas of Riyadh province of the KSA

Systematic review with meta-analysis: the accuracy of serological tests to support the diagnosis of coeliac disease

BACKGROUND: There is growing support for a biopsy avoidant approach to diagnose coeliac disease in both children and adults, using a serological diagnosis instead. AIMS: To assess the diagnostic accuracy of serological tests for coeliac disease in adults and children. METHODS: Seven electronic databases were searched between January 1990 and August 2020. Eligible diagnostic studies evaluated the accuracy of serological tests for coeliac disease against duodenal biopsy. Risk of bias assessment was performed using QUADAS-2. Bivariate random-effects meta-analyses were used to estimate serology sensitivity and specificity at the most commonly reported thresholds. RESULTS: 113 studies (n = 28,338) were included, all in secondary care populations. A subset of studies were included in meta-analyses due to variations in diagnostic thresholds. Summary sensitivity and specificity of immunoglobulin A (IgA) anti-tissue transglutaminase were 90.7% (95% confidence interval: 87.3%, 93.2%) and 87.4% (84.4%, 90.0%) in adults (5 studies) and 97.7% (91.0%, 99.4%) and 70.2% (39.3%, 89.6%) in children (6 studies); and of IgA endomysial antibodies were 88.0% (75.2%, 94.7%) and 99.6% (92.3%, 100%) in adults (5 studies) and 94.5% (88.9%, 97.3%) and 93.8% (85.2%, 97.5%) in children (5 studies). CONCLUSIONS: Anti-tissue transglutaminase sensitivity appears to be sufficient to rule out coeliac disease in children. The high specificity of endomysial antibody in adults supports its use to rule in coeliac disease. This evidence underpins the current development of clinical guidelines for a serological diagnosis of coeliac disease. Studies in primary care are needed to evaluate serological testing strategies in this setting

No role for quality scores in systematic reviews of diagnostic accuracy studies

BACKGROUND: There is a lack of consensus regarding the use of quality scores in diagnostic systematic reviews. The objective of this study was to use different methods of weighting items included in a quality assessment tool for diagnostic accuracy studies (QUADAS) to produce an overall quality score, and to examine the effects of incorporating these into a systematic review. METHODS: We developed five schemes for weighting QUADAS to produce quality scores. We used three methods to investigate the effects of quality scores on test performance. We used a set of 28 studies that assessed the accuracy of ultrasound for the diagnosis of vesico-ureteral reflux in children. RESULTS: The different methods of weighting individual items from the same quality assessment tool produced different quality scores. The different scoring schemes ranked different studies in different orders; this was especially evident for the intermediate quality studies. Comparing the results of studies stratified as "high" and "low" quality based on quality scores resulted in different conclusions regarding the effects of quality on estimates of diagnostic accuracy depending on the method used to produce the quality score. A similar effect was observed when quality scores were included in meta-regression analysis as continuous variables, although the differences were less apparent. CONCLUSION: Quality scores should not be incorporated into diagnostic systematic reviews. Incorporation of the results of the quality assessment into the systematic review should involve investigation of the association of individual quality items with estimates of diagnostic accuracy, rather than using a combined quality score

Forecasting the burden of type 2 diabetes mellitus in Qatar to 2050: A novel modeling approach.

AIMS: We developed and demonstrated a novel mathematical modeling approach to forecast the burden of type 2 diabetes mellitus (T2DM) and to investigate T2DM epidemiology for the purpose of informing public health policy and programming. METHODS: A population-level compartmental mathematical model was constructed and applied to Qatar. The model was stratified according to sex, age group, risk factor status, and T2DM status, and was parameterized by nationally-representative data. RESULTS: T2DM prevalence increased from 16.7% in 2012 to at least 24.0% by 2050. The rise in T2DM was most prominent among 45-54 years old. T2DM health expenditure was estimated to increase by 200-600% and to account for up to 32% of total health expenditure by 2050. Prevalence of obesity, smoking, and physical inactivity was predicted to increase from 41.4% to 51.0%, from 16.4% to 19.4%, and from 45.9% to 53.0%, respectively. The proportion of T2DM incidence attributed to obesity, smoking and physical inactivity was estimated at 57.5%, 1.8%, and 5.4%, respectively in 2012, and 65.7%, 2.1%, and 6.0%, respectively in 2050. Exploring different scenarios for the trends in risk factors, T2DM prevalence reached up to 37.7% by 2050. CONCLUSIONS: Using our innovative approach, a rising T2DM epidemic is predicted to continue in the next decades, driven by population growth, ageing and adverse trends in risk factors. Obesity was the principal risk factor explaining two-thirds of T2DM incidence. T2DM must be a national priority addressed by preventive and therapeutic interventions targeting T2DM and its modifiable risk factors