Free surface flows emerging from beneath a semi-infinite plate with constant vorticity

The free surface flow past a semi-infinite horizontal plate in a finite-depth fluid is considered. It is assumed that the fluid is incompressible and inviscid and that the flow approaches a uniform shear flow downstream. Exact relations are derived using conservation of mass and momentum for the case where the downstream free surface is flat. The complete nonlinear problem is solved numerically using a boundary integral method and these waveless solutions are shown to exist only when the height of the plate above the bottom is greater than the height of the uniform shear flow. Interesting results are found for various values of the constant vorticity. Solutions with downstream surface waves are also considered, and nonlinear results of this type are compared with linear results found previously. These solutions can be used to model the flow near the stern of a (two-dimensional) ship

Genetic Diversity and Population Parameters of Sea Otters, Enhydra lutris, before Fur Trade Extirpation from 1741–1911

All existing sea otter, Enhydra lutris, populations have suffered at least one historic population bottleneck stemming from the fur trade extirpations of the eighteenth and nineteenth centuries. We examined genetic variation, gene flow, and population structure at five microsatellite loci in samples from five pre-fur trade populations throughout the sea otter's historical range: California, Oregon, Washington, Alaska, and Russia. We then compared those values to genetic diversity and population structure found within five modern sea otter populations throughout their current range: California, Prince William Sound, Amchitka Island, Southeast Alaska and Washington. We found twice the genetic diversity in the pre-fur trade populations when compared to modern sea otters, a level of diversity that was similar to levels that are found in other mammal populations that have not experienced population bottlenecks. Even with the significant loss in genetic diversity modern sea otters have retained historical structure. There was greater gene flow before extirpation than that found among modern sea otter populations but the difference was not statistically significant. The most dramatic effect of pre fur trade population extirpation was the loss of genetic diversity. For long term conservation of these populations increasing gene flow and the maintenance of remnant genetic diversity should be encouraged

Tending to Society, Tending to Yourself: The Roles of Culture

Abstract: This paper addresses the role that cultural activities may play in the lives of youth. First, it reviews the general roles that culture is argued to play in society. It then looks at a schema of communications in an individual's life, hinting at the roles culture may play in this and arguing that studying culture and youth is part of a more comprehensive research framework in order to place the particular role of culture and youth into a larger picture. It ends by reviewing concrete examples of research on youth and culture, highlighting existing strategic constraints and proposing the need for a more intensive and more broadly based research of the impacts of culture on individuals which would contribute to better understanding and, ultimately, more appropriate culture policies and programs. Résumé: Cette étude adresse le rôle que les activités culturelles peuvent jouer dans la vie des jeunes. D'abord, elle passe en revue les rôles généraux que la culture est censée jouer dans la société. Ensuite, elle examine un schéma de communications dans la vie de l'individu, suggérant quels rôles la culture peut jouer dans une telle situation et soutenant que l'étude de la culture et de la jeunesse devraient faire partie d'un cadre de recherche élargi de manière à situer le rôle particulier de la culture et de la jeunesse dans un contexte plus large. L'étude conclut en examinant des exemples concrets de recherche sur culture et jeunesse, soulignant les contraintes stratégiques actuelles et affirmant le besoin d'étudier les effets de la culture sur les individus de manière plus intensive et mieux assise. Une telle recherche pourrait contribuer à une meilleure compréhension de ces effets et, finalement, à des politiques et des programmes culturels plus appropriés

Australian guideline on wound healing interventions to enhance healing of foot ulcers: part of the 2021 Australian evidence-based guidelines for diabetes-related foot disease

Background: Diabetes-related foot ulceration (DFU) has a substantial burden on both individuals and healthcaresystems both globally and in Australia. There is a pressing need for updated guidelines on wound healinginterventions to improve outcomes for people living with DFU. A national expert panel was convened to developnew Australian evidence-based guidelines on wound healing interventions for people with DFU by adaptingsuitable international guidelines to the Australian context.Methods: The panel followed National Health and Medical Research Council (NHMRC) procedures to adapt suitableinternational guidelines by the International Working Group of the Diabetic Foot (IWGDF) to the Australian context.The panel systematically screened, assessed and judged all IWGDF wound healing recommendations using ADAPTEand GRADE frameworks for adapting guidelines to decide which recommendations should be adopted, adapted orexcluded in the Australian context. Each recommendation had their wording, quality of evidence, and strength ofrecommendation re-evaluated, plus rationale, justifications and implementation considerations provided for theAustralian context. This guideline underwent public consultation, further revision and approval by ten national peakbodies.Results: Thirteen IWGDF wound healing recommendations were evaluated in this process. After screening, ninerecommendations were adopted and four were adapted after full assessment. Two recommendations had theirstrength of recommendations downgraded, one intervention was not currently approved for use in Australia, oneintervention specified the need to obtain informed consent to be acceptable in Australia, and another wasreworded to clarify best standard of care. Overall, five wound healing interventions have been recommended ashaving the evidence-based potential to improve wound healing in specific types of DFU when used in conjunctionwith other best standards of DFU care, including sucrose-octasulfate impregnated dressing, systemic hyperbaricoxygen therapy, negative pressure wound therapy, placental-derived products, and the autologous combinedleucocyte, platelet and fibrin dressing. The six new guidelines and the full protocol can be found at: https://diabetesfeetaustralia.org/new-guidelines/Conclusions: The IWGDF guideline for wound healing interventions has been adapted to suit the Australiancontext, and in particular for geographically remote and Aboriginal and Torres Strait Islander people. This newnational wound healing guideline, endorsed by ten national peak bodies, also highlights important considerationsfor implementation, monitoring, and future research priorities in Australia

Defective endogenous proviruses are expressed in feline lymphoid cells: evidence for a role in natural resistance to subgroup B feline leukemia viruses.

Endogenous feline leukemia virus (FeLV)-related sequences (enFeLV) are a family of proviral elements found in domestic cats and their close relatives. These elements can recombine with exogenous, infectious FeLVs of subgroup A (FeLV-A), giving rise to host range variants of FeLV-B. We found that a subset of defective enFeLV proviruses is highly expressed in lymphoma cell lines and in a variety of primary tissues, including lymphoid tissues from healthy specific-pathogen-free cats. At least two RNA species were detected, a 4.5-kb RNA containing gag, env, and long terminal repeat sequences and a 2-kb RNA containing env and long terminal repeat sequences. Cloning of enFeLV cDNA from two FeLV-free lymphoma cell lines (3201 and MCC) revealed a long open reading frame (ORF) encoding a truncated env gene product corresponding to the N-terminal portion of gp70env. Interestingly, all of three natural FeLV-B isolates include 3' env sequences which are missing from the highly transcribed subset and hence must be derived from other enFeLV elements. The enFeLV env ORF cDNA clones were closely similar to a previously characterized enFeLV provirus, CFE-16, but were polymorphic at a site corresponding to an exogenous FeLV neutralization epitope. Site-specific antiserum raised to a C-terminal 30-amino-acid peptide of the enFeLV env ORF detected an intracellular product of 35 kDa which was also shed from cells in stable form. Expression of the 35-kDa protein correlated with enFeLV RNA levels and was negatively correlated with susceptibility to infection with FeLV-B. Cell culture supernatant containing the 35-kDa protein specifically blocked infection of permissive fibroblast cells with FeLV-B isolates. We suggest that the truncated env protein mediates resistance by receptor blockade and that this form of enFeLV expression mediates the natural resistance of cats to infection with FeLV-B in the absence of FeLV-A