Enhancing TCP Performance over Wireless Networks

TCP flow control algorithms have been designed for wireline networks where congestion is measured by packet loss due to buffer overflow. However, wireless networks also suffer from significant packet losses due to bit errors and handoffs. TCP responds to all the packet losses by invoking congestion control and avoidance algorithms and this results in degraded end-to-end performance in wireless networks. In this paper, we describe a Wireless Random Exponential Marking (WREM) scheme which effectively improves TCP performance over wireless networks by decoupling loss recovery from congestion control. Moreover, WREM is capable of handling the coexistence of both ECN-Capable and Non-ECN-Capable routers. We present simulation results to show its effectiveness and compatibility

Using AQM to improve TCP performance over wireless networks

TCP flow control algorithms have been designed for wireline networks where congestion is measured by packet loss due to buffer overflow. However, wireless networks also suffer from significant packet losses due to bit errors and handoffs. TCP responds to all the packet losses by invoking congestion control and avoidance algorithms and this results in degraded end-to-end performance in wireless networks. In this paper, we describe an Wireless Random Exponential Marking(WREM) scheme which effectively improves TCP performance over wireless networks by decoupling loss recovery from congestion control. Moreover, WREM is capable of handling the coexistence of both ECN-Capable and Non-ECN-Capable routers. We present simulation results to show its effectiveness and compatibility

Modeling the consequences of regional heterogeneity in human papillomavirus (HPV) vaccination uptake on transmission in Switzerland

Background: Completed human papillomavirus (HPV) vaccination by age 16 years among women in Switzerland ranges from 17 to 75% across 26 cantons. The consequences of regional heterogeneity in vaccination coverage on transmission and prevalence of HPV-16 are unclear. Methods: We developed a deterministic, population-based model that describes HPV-16 transmission among young adults within and between the 26 cantons of Switzerland. We parameterized the model using sexual behavior data from Switzerland and data from the Swiss National Vaccination Coverage Survey. First, we investigated the general consequences of heterogeneity in vaccination uptake between two sub-populations. We then compared the predicted prevalence of HPV-16 resulting from heterogeneous HPV vaccination uptake in all of Switzerland with homogeneous vaccination at an uptake that is identical to the national average (52%). Results: In our baseline scenario, HPV-16 prevalence in women is 3.34% when vaccination is introduced and begins to diverge across cantons, ranging from 0.19 to 1.20% after 15 years of vaccination. After the same time period, overall prevalence of HPV-16 in Switzerland is only marginally higher (0.63%) with heterogeneous vaccination uptake than with homogeneous uptake (0.59%). Assuming inter-cantonal sexual mixing, cantons with low vaccination uptake benefit from a reduction in prevalence at the expense of cantons with high vaccination uptake. Conclusions: Regional variations in uptake diminish the overall effect of vaccination on HPV-16 prevalence in Switzerland, but the effect size is small. Cantonal efforts towards HPV-prevalence reduction by increasing vaccination uptake are impaired by cantons with low vaccination uptake. Although the expected impact on national prevalence would be relatively small, harmonization of cantonal vaccination programs would reduce inter-cantonal differences in HPV-16 prevalence

De novo mutations drive the spread of macrolide resistant Mycoplasma genitalium : mathematical modelling study

The rapid spread of antimicrobial resistance in sexually transmitted infections caused by Mycoplasma genitalium is a growing concern. It is not yet clear to what degree macrolide resistance in M. genitalium results from the emergence of de novo mutations or the transmission of resistant strains. We analysed epidemiological data and developed a compartmental model to investigate the contribution of de novo macrolide resistance mutations to the spread of antimicrobial resistant M. genitalium. We fitted the model to data from France, Sweden and Denmark and estimated treatment rates and the time point of azithromycin introduction. In a meta-analysis of six studies, we estimated that de novo resistance develops in 12% (95% CI 7-17%, I2 44%) of azithromycin treated M. genitalium infections. Our model shows that the high probability of de novo resistance accelerates the spread of antimicrobial resistant M. genitalium in comparison with lower probabilities. The estimated per capita treatment rate in France was lower than in Denmark and Sweden but confidence intervals for the three estimates overlap. The estimated dates of introduction of azithromycin in each country are consistent with published reports. We conclude that clinical management strategies for M. genitalium should seek to limit the unnecessary use of macrolides

Understanding the spread of de novo and transmitted macrolide-resistance in Mycoplasma genitalium.

Background The rapid spread of azithromycin resistance in sexually transmitted Mycoplasma genitalium infections is a growing concern. It is not yet clear to what degree macrolide resistance in M. genitalium results from the emergence of de novo mutations or the transmission of resistant strains. Methods We developed a compartmental transmission model to investigate the contribution of de novo macrolide resistance mutations to the spread of antimicrobial-resistant M. genitalium. We fitted the model to resistance data from France, Denmark and Sweden, estimated the time point of azithromycin introduction and the rates at which infected individuals receive treatment, and projected the future spread of resistance. Results The high probability of de novo resistance in M. genitalium accelerates the early spread of antimicrobial resistance. The relative contribution of de novo resistance subsequently decreases, and the spread of resistant infections in France, Denmark and Sweden is now mainly driven by transmitted resistance. If treatment with single-dose azithromycin continues at current rates, macrolide-resistant M. genitalium infections will reach 25% (95% confidence interval, CI [9-30]%) in France, 84% (95% CI [36-98]%) in Denmark and 62% (95% CI [48-76]%) in Sweden by 2025. Conclusions Blind treatment of urethritis with single-dose azithromycin continues to select for the spread of macrolide resistant M. genitalium. Clinical management strategies for M. genitalium should limit the unnecessary use of macrolides

Pricing Link by Time

The combination of loss-based TCP and drop-tail routers often results in full buffers, creating large queueing delays. The challenge with parameter tuning and the drastic consequence of improper tuning have discouraged network administrators from enabling AQM even when routers support it. To address this problem, we propose a novel design principle for AQM, called the pricing-link-by-time (PLT) principle. PLT increases the link price as the backlog stays above a threshold β, and resets the price once the backlog goes below β. We prove that such a system exhibits cyclic behavior that is robust against changes in network environment and protocol parameters. While β approximately controls the level of backlog, the backlog dynamics are invariant for β across a wide range of values. Therefore, β can be chosen to reduce delay without undermining system performance. We validate these analytical results using packet-level simulation

Urban square dance in Haidian District of Beijing: Issues and suggestions

With the remarkable success of the 2008 Beijing Olympic Games, the country vigorously advocated the people to actively participate in fitness and exercising nationwide. People responded to the call of government by actively participating in Square Dances, pushing the development of square dance to a climax. Following the development of recent years, such mass culture has prospered among public. There are a lot of parks in Haidian District, Beijing, with a total of 24 parks located around the city center and countryside. The 8 parks mentioned in this paper have high green coverage rate, wide open spaces, and suitable environment for the public to conduct fitness activities. Since these parks are located near residential areas, citizens make them as their first choice to develop leisure and entertainment activities. It is not a rare to have square dance teams occupying the open spaces in the parks. These square dance teams have been established for 2 to 20 years, spontaneously made up by public with different genders, ages and professional background. This paper focuses on the development of square dances in the parks of Haidian District, Beijing and collects its first-hand data through field survey method, thus showing a more comprehensive grasp to the development of square dances in Haidian District. During the organization of such square dance activities, site disputations were occurred as the park was relatively small for the large participating crowd. The level of the square dance teams was uneven, because of lacking professional instructors. Aiming to create an organized and sustainable square dance environment in Haidian District, it is suggested that national and governmental systems and policies should make full use of the social resources available to improve outdoor fitness sites, increase professional square dance instructors and support volunteers, to create a harmonious environment for the society

Core Competencies for Integrative Medicine Fellowship Training Programs

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140347/1/acm.2014.5258.abstract.pd

Congestion window control based on queuing delay and packet loss

A method of controlling size of a congestion window, includes, at a transmitting device, transmitting a plurality of data packets over a communication channel from the transmitting device to a receiver, determining a queuing delay and a loss rate of the transmission, comparing the queuing delay to a threshold queuing delay, comparing the loss rate to a threshold loss rate, and in response to a determination that the queuing delay is greater than the threshold queuing delay and the loss rate is greater than the threshold loss rate, resetting the size of the congestion window in accordance with a function of the current size of the congestion window, the queuing delay, and the loss rate, wherein at equilibrium the function generates a value inversely proportional to a weighted sum of an excess queuing delay and an excess loss rate

Integrative analysis workflow for the structural and functional classification of C-type lectins

<p>Abstract</p> <p>Background</p> <p>It is important to understand the roles of C-type lectins in the immune system due to their ubiquity and diverse range of functions in animal cells. It has been observed that currently confirmed C-type lectins share a highly conserved domain known as the C-type carbohydrate recognition domain (CRD). Using the sequence profile of the CRD, an increasing number of putative C-type lectins have been identified. Hence, it is highly needed to develop a systematic framework that enables us to elucidate their carbohydrate (glycan) recognition function, and discover their physiological and pathological roles.</p> <p>Results</p> <p>Presented herein is an integrated workflow for characterizing the sequence and structural features of novel C-type lectins. Our workflow utilizes web-based queries and available software suites to annotate features that can be found on the C-type lectin, given its amino acid sequence. At the same time, it incorporates modeling and analysis of glycans - a major class of ligands that interact with C-type lectins. Thereafter, the results are analyzed together with context-specific knowledge to filter off unlikely predictions. This allows researchers to design their subsequent experiments to confirm the functions of the C-type lectins in a systematic manner.</p> <p>Conclusions</p> <p>The efficacy and usefulness of our proposed immunoinformatics workflow was demonstrated by applying our integrated workflow to a novel C-type lectin -CLEC17A - and we report some of its possible functions that warrants further validation through wet-lab experiments.</p