Post-Meiotic Intra-Testicular Sperm Senescence in a Wild Vertebrate

There is growing interest in sperm senescence, both in its underlying mechanisms and evolutionary consequences, because it can impact the evolution of numerous life history traits. Previous studies have documented various types of sperm senescence, but evidence of post-meiotic intra-testicular sperm senescence in wild animals is lacking. To assess such senescence, we studied within-season changes in sperm motility in the common toad (Bufo bufo), where males produce all sperm prior to the breeding season. We found that males exposed to experimentally induced re-hibernation at the start of the breeding season, that is to experimentally lowered metabolic rates, stored sperm of significantly higher motility than males that were kept under seminatural conditions without females throughout the breeding season. This finding indicates that re-hibernation slows normal rates of sperm ageing and constitutes the first evidence to our knowledge of post-meiotic intra-testicular sperm senescence in a wild vertebrate. We also found that in males kept in seminatural conditions, sperm motility was positively related to the number of matings a male achieved. Thus, our results suggest that post-meiotic intratesticular sperm senescence does not have a genetically fixed rate and may be modulated by temperature and possibly by mating opportunities

My Little Sue In Blue

https://digitalcommons.library.umaine.edu/mmb-vp/2206/thumbnail.jp

Removal of luminal content protects the small intestine during hemorrhagic shock but is not sufficient to prevent lung injury.

The small intestine plays a key role in the pathogenesis of multiple organ failure following circulatory shock. Current results show that reduced perfusion of the small intestine compromises the mucosal epithelial barrier, and the intestinal contents (including pancreatic digestive enzymes and partially digested food) can enter the intestinal wall and transport through the circulation or mesenteric lymph to other organs such as the lung. The extent to which the luminal contents of the small intestine mediate tissue damage in the intestine and lung is poorly understood in shock. Therefore, rats were assigned to three groups: No-hemorrhagic shock (HS) control and HS with or without a flushed intestine. HS was induced by reducing the mean arterial pressure (30 mmHg; 90 min) followed by return of shed blood and observation (3 h). The small intestine and lung were analyzed for hemorrhage, neutrophil accumulation, and cellular membrane protein degradation. After HS, animals with luminal contents had increased neutrophil accumulation, bleeding, and destruction of E-cadherin in the intestine. Serine protease activity was elevated in mesenteric lymph fluid collected from a separate group of animals subjected to intestinal ischemia/reperfusion. Serine protease activity was elevated in the plasma after HS but was detected in lungs only in animals with nonflushed lumens. Despite removal of the luminal contents, lung injury occurred in both groups as determined by elevated neutrophil accumulation, permeability, and lung protein destruction. In conclusion, luminal contents significantly increase intestinal damage during experimental HS, suggesting transport of luminal contents across the intestinal wall should be minimized

Cyclic-routing of Unmanned Aerial Vehicles

© 2019 Various missions carried out by Unmanned Aerial Vehicles (UAVs) are concerned with permanent monitoring of a predefined set of ground targets under relative deadline constraints, i.e., the targets have to be revisited ‘indefinitely’ and there is an upper bound on the time between two consecutive successful scans of each target. A solution to the problem is a set of routes—one for each UAV—that jointly satisfy these constraints. Our goal is to find a solution with the least number of UAVs. We show that the decision version of the problem (given k, is there a solution with k UAVs?) is PSPACE-complete. On the practical side, we propose a portfolio approach that combines the strengths of constraint solving and model checking. We present an empirical evaluation of the different solution methods on several hundred randomly generated instances

On Metal-Insulator Transitions due to Self-Doping

We investigate the influence of an unoccupied band on the transport properties of a strongly correlated electron system. For that purpose, additional orbitals are coupled to a Hubbard model via hybridization. The filling is one electron per site. Depending on the position of the additional band, both, a metal--to--insulator and an insulator--to--metal transition occur with increasing hybridization. The latter transition from a Mott insulator into a metal via ``self--doping'' was recently proposed to explain the low carrier concentration in $\rm Yb_4As_3$. We suggest a restrictive parameter regime for this transition making use of exact results in various limits. The predicted absence of the self--doping transition for nested Fermi surfaces is confirmed by means of an unrestricted Hartree--Fock approximation and an exact diagonalization study in one dimension. In the general case metal--insulator phase diagrams are obtained within the slave--boson mean--field and the alloy--analog approximation.Comment: 9 pages, Revtex, 6 postscript figure

Educational aspirations in inner city schools

The research aimed to assess the nature and level of pupils’ educational aspirations and to elucidate the factors that influence these aspirations. A sample of five inner city comprehensive secondary schools were selected by their Local Authority because of poor pupil attendance, below average examination results and low rates of continuing in full-time education after the age of 16. Schools were all ethnically mixed and co-educational. Over 800 pupils aged 12-14 completed a questionnaire assessing pupils’ experience of home, school and their peers. A sub-sample of 48 pupils selected by teachers to reflect ethnicity and ability levels in individual schools also participated in detailed focus group interviews. There were no significant differences in aspirations by gender or year group, but differences between ethnic groups were marked. Black African, Asian Other and Pakistani groups had significantly higher educational aspirations than the White British group, who had the lowest aspirations. The results suggest the high aspirations of Black African, Asian Other and Pakistani pupils are mediated through strong academic self-concept, positive peer support, a commitment to schooling and high educational aspirations in the home. They also suggest that low educational aspirations may have different mediating influences in different ethnic groups. The low aspirations of White British pupils seem to relate most strongly to poor academic self-concept and low educational aspirations in the home, while for Black Caribbean pupils disaffection, negative peers and low commitment to schooling appear more relevant. Interviews with pupils corroborated the above findings and further illuminated the factors students described as important in their educational aspirations. The results are discussed in relation to theories of aspiration which stress its nature as a cultural capacity

Management information systems for community based interventions to improve health::Qualitative study of stakeholder perspectives

Abstract Background Community based providers are well place to deliver behavioural interventions to improve health. Good project management and reliable outcome data are needed to efficiently deliver and evaluate such interventions, and Management information systems (MIS) can facilitate these processes. We explored stakeholders perspectives on the use of MIS in community based behavioural interventions. Methods Stakeholders, purposively selected to provide a range of MIS experience in the delivery of community based behavioural interventions to improve health (public health commissioners, intervention service managers, project officers, health researchers and MIS designers), were invited to participate in individual semi-structured interviews. We used a topic guide and encouraged stakeholders to reflect on their experiences.: Interviews were recorded, transcribed and analysed using five steps of Framework analysis. We applied an agreed coding framework and completed the interviews when no new themes emerged. Results We interviewed 15 stakeholders. Key themes identified were: (i) MIS access; (ii) data and its function; (iii) MIS development and updating. Within these themes the different experiences, needs, use, training and expertise of stakeholders and the variation and potential of MIS were evidenced. Interviews advised the need to involve stakeholders in MIS design and development, build-in flexibility to accommodate MIS refinement and build on effective MIS. Conclusions Findings advised involving stakeholders, early in the design process. Designs should build on existing MIS of proven utility and ensure flexibility in the design, to incorporate adaptations and ongoing system development in response to early MIS use and evolving stakeholder needs