Drift by drift: effective population size is limited by advection

<p>Abstract</p> <p>Background</p> <p>Genetic estimates of effective population size often generate surprising results, including dramatically low ratios of effective population size to census size. This is particularly true for many marine species, and this effect has been associated with hypotheses of "sweepstakes" reproduction and selective hitchhiking.</p> <p>Results</p> <p>Here we show that in advective environments such as oceans and rivers, the mean asymmetric transport of passively dispersed reproductive propagules will act to limit the effective population size in species with a drifting developmental stage. As advection increases, effective population size becomes decoupled from census size as the persistence of novel genetic lineages is restricted to those that arise in a small upstream portion of the species domain.</p> <p>Conclusion</p> <p>This result leads to predictions about the maintenance of diversity in advective systems, and complements the "sweepstakes" hypothesis and other hypotheses proposed to explain cases of low allelic diversity in species with high fecundity. We describe the spatial extent of the species domain in which novel allelic diversity will be retained, thus determining how large an appropriately placed marine reserve must be to allow the persistence of endemic allelic diversity.</p

Extinction hazards in experimental Daphnia magna populations: effects of genotype diversity and environmental variation

Extinction is ubiquitous in natural systems and the ultimate fate of all biological populations. However, the factors that contribute to population extinction are still poorly understood, particularly genetic diversity and composition. A laboratory experiment was conducted to examine the influences of environmental variation and genotype diversity on persistence in experimental Daphnia magna populations. Populations were initiated in two blocks with one, two, three, or six randomly selected and equally represented genotypes, fed and checked for extinction daily, and censused twice weekly over a period of 170 days. Our results show no evidence for an effect of the number of genotypes in a population on extinction hazard. Environmental variation had a strong effect on hazards in both experimental blocks, but the direction of the effect differed between blocks. In the first block, variable environments hastened extinction, while in the second block, hazards were reduced under variable food input. This occurred despite greater fluctuations in population size in variable environments in the second block of our experiment. Our results conflict with previous studies, where environmental variation consistently increased extinction risk. They are also at odds with previous studies in other systems that documented significant effects of genetic diversity on population persistence. We speculate that the lack of sexual reproduction, or the phenotypic similarity among our experimental lines, might underlie the lack of a significant effect of genotype diversity in our study

A 15-year-old boy with huge facial swelling, recurrent severe epistaxis, progressive proptosis, nasal obstruction and impaired hearing on right side

This article has no abstract. The first 100 words appear below: A 15-year-old male hailing from Khagrachhari was admitted into the department with the complaints of swelling on the right side of face for 10 months with recurrent severe epistaxis, progressive proptosis, unilateral nasal obstruction and impairment of hearing for two months. On extraoral examination, there was a firm non-tender, nonmobile, fixed swelling on the right side of cheek causing facial asymmetry measuring about 10 × 12 cm in size extending from upper eyelid to middle of the right cheek supero-inferiorly and pre-auricular area to the medial wall of nose postero-anteriorl

A 15-year-old boy with huge facial swelling, recurrent severe epistaxis, progressive proptosis, nasal obstruction and impaired hearing on right side

This article has no abstract. The first 100 words appear below: A 15-year-old male hailing from Khagrachhari was admitted into the department with the complaints of swelling on the right side of face for 10 months with recurrent severe epistaxis, progressive proptosis, unilateral nasal obstruction and impairment of hearing for two months. On extraoral examination, there was a firm non-tender, nonmobile, fixed swelling on the right side of cheek causing facial asymmetry measuring about 10 × 12 cm in size extending from upper eyelid to middle of the right cheek supero-inferiorly and pre-auricular area to the medial wall of nose postero-anteriorl

Resources for Supporting Mathematics and Data Science Instructors During COVID-19

In late May of 2020, a few months after the raging COVID-19 pandemic forced university faculty to quickly switch to online teaching, the Associated Colleges of the South (ACS) released a call for grant applications to support working groups to help faculty within our consortium who will be teaching during the pandemic (e.g., from hybrid courses with some remote/online components to fully remote/online courses; socially distanced face-to-face courses). We replied to this call and the ACS awarded the six of us (from four ACS schools) a Summer Rapid Response Grant in early June. The grant funded our efforts to create and provide to other faculty Mathematics and Data Science Resources to Support Socially Relevant Teaching in the Time of COVID-19. This paper summarizes our efforts and includes the resources that we developed

Water budgets of cave crickets, Hadenoecus subterraneus and camel crickets, Ceuthophilus stygius

1. 1. Studies of cave and camel crickets from cave entrances in Mammoth Cave National Park have produced estimates of total water budgets and component contributions to water balance.2. 2. Weight specific (mg/g crop-free live weight/hr) total water loss (3.200 vs 2.220) and water gained in food (2.393 vs 1.902) are greater in cave than in camel crickets, respectively.3. 3. Weight specific evaporative water loss in both humid, still air (2.269 vs 1.325) and dry, moving air (15.28 vs 9.85) is greater in cave than in camel crickets, respectively.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26939/1/0000505.pd

Bioenergetics of the cave cricket, Hadenoecus subterraneus

1. 1. In late spring, cave crickets in Mammoth Cave National Park were investigated in order that their bioenergetics might be elucidated.2. 2. A predictive relation between crop-empty live weight and hind femur length independent of sex was found.3. 3. Long-term weight loss patterns were 1.55 and 1.19mg/hr for females and males, respectively, suggesting feeding intervals of 11.5 and 9.9 days.4. 4. Calorific assimilation efficiencies were found to be 80.4% for females and 82.5% for males.5. 5. The estimated maximal metabolic rates were half that expected for insects of similar mass.6. 6. The mixed waste calorific levels were found to be exceptionally low.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26417/1/0000504.pd

Perceptions of tuberculosis patients about private providers before and after implementation of Revised National Tuberculosis Control Programme

Background: Most of the persons with chest symptoms in India approach private providers (PPs) for health care. It has been observed that patients who start treatment with PPs for tuberculosis (TB) frequently switch over subsequently to the public sector. The reasons for this discontinuation and their perceptions of the TB care provided by the PPs are unknown. Objective: To document the perceptions about PPs India’s Revised National TB Control Programme (RNTCP) and the reasons for discontinuation of treatment with PPs and subsequent attendance at a public provider. Methods: This was a cross sectional study on patients registered under TB programme during 1997 and 2005in rural and urban areas. During this period patients who were initially diagnosed and treated for TB in a private clinic and subsequently shifted to public health facility were considered for the study. A semi-structured interview schedule was used to collect the factors related to patient’s perceptions on PPs, the factors responsible for initiating treatment with PPs, reasons for discontinuing treatment with PPs, and their willingness to continue treatment from government health facilities were collected. This data was compared with data collected in 1997 before implementation of the RNTCP. Results: A total of 1000 and 1311 TB patients were registered during 1997 and 2005 respectively. Among them, 203 (20%) and 104 (8%) patients were identified as having been initially diagnosed and started on TB treatment by PPs and subsequently shifted to government health facilities. There were significant changes in reasons for selecting PPs between the two periods: being convenient (47% vs 10%; p<0.001), quality care (41% vs 19%; p<0.001), motivated by others (49% vs 19%; p<0.001), confidentiality (19% vs 9%; p<0.05) and known doctor (6% vs 28%; p<0.001) respectively. Financial problems were the most common reason for discontinuation of treatment in both periods. The use of sputum test for diagnosing TB by PPs was significantly increased after RNTCP implementation. Conclusion: This study suggests that slowly perceptions of patients have changed towards PPs, and RNTCP has begun to gain acceptance amongst patients in terms of convenience, confidentiality and personal care

Care Seeking Behavior of Chest Symptomatics: A Community Based Study Done in South India after the Implementation of the RNTCP

INTRODUCTION: With the creation of the Revised National TB Control Programme (RNTCP), tuberculosis services have become decentralized and more accessible. A 1997 study prior to RNTCP implementation reported that most chest symptomatics accessed first private health care facilities and a general dissatisfaction with government health facilities. The study was repeated post-RNTCP implementation to gain insight into the current care seeking behavior of chest symptomatics. METHODOLOGY: A cross-sectional community-based study carried out between March-August 2008 in 4 sites (2 rural [R] and 2 urban [U]) from the same two districts of Chennai and Madurai, southern India, as in the 1997 study. Six hundred and forty chest symptomatics were identified (R 314; U 326), and detailed interviews were done for 606 (R311; U295). RESULTS: Prevalence of chest symptomatics in the urban and rural areas were 2.7% and 4.9% respectively (p<0.01), and was found to increase with age (Chi-square for trend, p<0.01). Longer delays in seeking care were seen amongst symptomatics above 45 years of age (p 0.01), and those who had taken previous TB treatment (p=0.05). Overall, 50% (222/444) of the chest symptomatics approached a government health care facility first (R 142 (61%); U 80 (38%), p=or  <0.001). This was significantly (p<0.001) more than were observed in the 1997 study, where only 38.4% approached a government facility first. Sixty two (28%) of the 222 made a second visit to a government facility (R26%; U31%), while 17% shifted to a private facility (R14%; U21%). Dissatisfaction with the health care facility was one of the major reasons expressed. CONCLUSIONS: It appears that the RNTCP has had an impact in the community with regard to the availability and accessibility of TB services in government health facilities. However the relatively high levels of subsequent shifting to private health facilities calls for urgent action to make government facilities more patients friendly with quality care facilities in the delivery of RNTCP services

Programmatic Management of Drug-Resistant Tuberculosis: An Updated Research Agenda.

There are numerous challenges in delivering appropriate treatment for multidrug-resistant tuberculosis (MDR-TB) and the evidence base to guide those practices remains limited. We present the third updated Research Agenda for the programmatic management of drug-resistant TB (PMDT), assembled through a literature review and survey