5,904 research outputs found

    Process reconstruction from incomplete and/or inconsistent data

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    We analyze how an action of a qubit channel (map) can be estimated from the measured data that are incomplete or even inconsistent. That is, we consider situations when measurement statistics is insufficient to determine consistent probability distributions. As a consequence either the estimation (reconstruction) of the channel completely fails or it results in an unphysical channel (i.e., the corresponding map is not completely positive). We present a regularization procedure that allows us to derive physically reasonable estimates (approximations) of quantum channels. We illustrate our procedure on specific examples and we show that the procedure can be also used for a derivation of optimal approximations of operations that are forbidden by the laws of quantum mechanics (e.g., the universal NOT gate).Comment: 9pages, 5 figure

    Significant familial differences in the frequency of abortion and Toxoplasma gondii infection within a flock of Charollais sheep

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    A study was carried out to investigate the frequencies of abortion and congenital Toxoplasma gondii infection within 27 families (765 individuals) of a pedigree Charollais sheep flock maintained on a working farm in Worcestershire, UK, since 1992. Pedigree lambing records were analysed to establish the frequency of abortion for each family. The frequency of congenital infection was determined for each family by PCR analysis of tissue samples taken from newborn lambs. Atotal of 155 lambs were tested for congenital T. gondii infection, which were all born during the study period 2000–2003. Significant differences in the frequency of abortion between sheep families within this flock were observed with frequencies ranging between 0% and 48% (P<0.01). Significantly different infection frequencies with T. gondii were also observed for different families and ranged between 0% and 100% (P<0.01). Although the actual cause of each abortion was not verified, a highly significant positive correlation was found to exist between the frequency of abortion and the frequency of T. gondii infection in the same families (P<0.01). The data presented here raise further questions regarding the significance of congenital transmission of T. gondii within sheep populations, the possible successive vertical transmission of T. gondii within families of sheep, and the potential role of inherited genetic susceptibility to abortion with respect to T. gondii infection. This work invites further study into the epidemiology of ovine toxoplasmosis and may have implications for sheep husbandry methods in the future. Key words: Toxoplasma gondii, ovine, toxoplasmosis, congenital, transmission, pedigree, sheep

    High levels of congenital transmission of toxoplasma gondii in longitudinal and cross-sectional studies on sheep farms provides evidence of vertical transmission in ovine hosts

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    Recent research suggests that vertical transmission may play an important role in sustaining Toxoplasma gondii infection in some species. We report here that congenital transmission occurs at consistently high levels in pedigree Charollais and outbred sheep flocks sampled over a 3-year period. Overall rates of transmission per pregnancy determined by PCR based diagnosis, were consistent over time in a commercial sheep flock (69%) and in sympatric (60%) and allopatric (41%) populations of Charollais sheep. The result of this was that 53·7% of lambs were acquiring an infection prior to birth: 46·4% of live lambs and 90·0% of dead lambs (in agreement with the association made between T. gondii and abortion). No significant differences were observed between lamb sexes. Although we cannot distinguish between congenital transmission occurring due to primary infection at pregnancy or reactivation of chronic infection during pregnancy, our observations of consistently high levels of congenital transmission over successive lambings favour the latter

    The prevalence of Neospora caninum and co-infection with Toxoplasma gondii by PCR analysis in naturally occurring mammal populations

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    Neospora caninum and Toxoplasma gondii are closely related intracellular protozoan parasites associated with bovine and ovine abortion respectively. Little is known about the extent of Neospora/Toxoplasma co-infection in naturally infected populations of animals. Using nested PCR techniques, based on primers from the Nc5 region of N. caninum and SAG1 for T. gondii, the prevalence of N. caninum and its co-infection with T. gondii were investigated in populations of Mus domesticus, Rattus norvegicus and aborted lambs (Ovis aries). A low frequency of infection with N. caninum was detected in the Mus domesticus (3%) and Rattus norvegicus (4·4%) populations. A relatively high frequency of infection with N. caninum was detected in the brains of aborted lambs (18·9%). There was no significant relationship between N. caninum and T. gondii co-infection. Investigation of the tissue distribution of Neospora, in aborted lambs, showed that Neospora could not be detected in tissues other than brain and this was in contrast to Toxoplasma where the parasite could be frequently detected in a range of tissues

    Searching for candidate genes for male infertility

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    Aim: We describe an approach to search for candidate genes for male infertility using the two human genome databases: the public University of California at Santa Cruz (UCSC) and private Celera databases which list known and predicted gene sequences and provide related information such as gene function, tissue expression, known mutations and single nucleotide polymorphisms (SNPs). Methods and Results: To demonstrate this in silico research, the following male infertility candidate genes were selected: (1) human BOULE, mutations of which may lead to germ cell arrest at the primary spermatocyte stage, (2) mutations of casein kinase 2 alpha genes which may cause globozoospermia, (3) DMR-N9 which is possibly involved in the spermatogenic defect of myotonic dystrophy and (4) several testes expressed genes at or near the breakpoints of a balanced translocation associated with hypospermatogenesis. We indicate how information derived from the human genome databases can be used to confirm these candidate genes may be pathogenic by studying RNA expression in tissue arrays using in situ hybridization and gene sequencing. Conclusion: The paper explains the new approach to discovering genetic causes of male infertility using information about the human genome

    Long-Distance Wind-Dispersal of Spores in a Fungal Plant Pathogen: Estimation of Anisotropic Dispersal Kernels from an Extensive Field Experiment

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    Given its biological significance, determining the dispersal kernel (i.e., the distribution of dispersal distances) of spore-producing pathogens is essential. Here, we report two field experiments designed to measure disease gradients caused by sexually- and asexually-produced spores of the wind-dispersed banana plant fungus Mycosphaerella fijiensis. Gradients were measured during a single generation and over 272 traps installed up to 1000 m along eight directions radiating from a traceable source of inoculum composed of fungicide-resistant strains. We adjusted several kernels differing in the shape of their tail and tested for two types of anisotropy. Contrasting dispersal kernels were observed between the two types of spores. For sexual spores (ascospores), we characterized both a steep gradient in the first few metres in all directions and rare long-distance dispersal (LDD) events up to 1000 m from the source in two directions. A heavy-tailed kernel best fitted the disease gradient. Although ascospores distributed evenly in all directions, average dispersal distance was greater in two different directions without obvious correlation with wind patterns. For asexual spores (conidia), few dispersal events occurred outside of the source plot. A gradient up to 12.5 m from the source was observed in one direction only. Accordingly, a thin-tailed kernel best fitted the disease gradient, and anisotropy in both density and distance was correlated with averaged daily wind gust. We discuss the validity of our results as well as their implications in terms of disease diffusion and management strategy

    One novel virus, different beliefs as playmakers towards disease spread in Africa: looking at COVID-19 from a religious lens.

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    Religious and spiritual observances that draw large people together are pervasive in many parts of the world, including Africa. With the recent emergence of COVID-19, these mass religious gatherings may pose significant threats to human health. Given the compromised healthcare systems in many parts of Africa, faith-based institutions have a huge responsibility towards the management of the potential spread of the virus through effective organizational strategies or interventions. This essay sheds light on what the novel virus has to do with religion, the role of religious practices in inhibiting or spreading COVID-19, and what appropriate evidence-based interventions religious or faith-based organizations could adopt to help prevent the spread of the disease in Africa through a unity of thoughts for religious action

    Africa's COVID-19 Situation in Focus and Recent Happenings: A Mini Review.

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    Given that COVID-19 (SARS-CoV-2) has crept into Africa, a major public health crisis or threat continues to linger on the continent. Many local governments and various stakeholders have stepped up efforts for early detection and management of COVID-19. This mini review highlights the current trend in Africa, history and general epidemiological information on the virus. Current ongoing efforts (e.g., improving testing capacity) and some effective ways (e.g., intensified surveillance, quick detection, contact tracing, isolation measures [e.g., quarantine], and social distancing) of preventing and managing COVID-19 in Africa are described. The review concludes by emphasizing the need for public health infrastructure development (e.g., laboratories, infectious disease centers, regional hospitals) and human capacity building for combating COVID-19 and potential future outbreaks. Additionally, regular public health educational campaigns are urgently required. Future epidemiological studies to ascertain case fatality and mortality trends across the continent for policy directions are necessary

    COVID-19 Pandemic Worsening Gender Inequalities for Women and Girls in Sub-Saharan Africa

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    Pandemics such as COVID-19 have often resulted in international, national and sub-regional crises, with considerable inequities across many societies. With the already existing structural and socio-economic inequalities in sub-Saharan Africa, the stay-at-home orders, lockdowns, and shutdowns across the sub-regional states could worsen and have a tremendous impact on vulnerable groups. Numerous studies across a variety of contexts have well-documented gender, and cultures on varied health outcomes. However, these have not been contextualized in sub-Saharan Africa in the light of the COVID-19 pandemic. This mini review discusses the ways by which COVID-19 has impacted the lives of girls and women across sub-Saharan Africa and the strategies that can help mitigate these challenges. The mini review specifically shares light on a wide array of dimensions where the inequities exist. These include the disproportionate areas affected by COVID-19; household inequities; educational inequalities; work/employment inequalities; disparities related to healthcare, sexual and reproductive health as well as housing inequities. Conclusively, the review accentuates the need for sub-Saharan African countries to adopt low-cost preventive measures such as discouraging mass gatherings (e.g., local community gatherings), and face masking with non-medical cloth like masks for the local populace as these are crucial in managing the spread of the virus among disproportionate women population. For localities with limited access to handwashing facilities, alternative strategies like alcohol-based hand rub solutions could be deployed. The complex interrelated disparities require a broad set of policy actions to lessen the current burden faced by many women in sub-Saharan Africa

    Mapping Evidence of Impacts of COVID-19 Outbreak on Sexual and Reproductive Health: A Scoping Review

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    Introduction: The emergence of the coronavirus disease 2019 (COVID-19) pandemic has rapidly transformed the pre-existing worldwide sexual and reproductive health environment. The provision and supply of contraceptives, and a wide variety of sexual health, new-born, and maternal health services have been seriously affected. Thus, this scoping review mapped the available evidence on the impacts of the COVID-19 outbreak on sexual and reproductive health. Methods: Arksey and O’Malley’s methodological framework guided this scoping review. A search was conducted from the following databases: Embase, PubMed, CINAHL, Scopus, WOS, and AJOL. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) chart and PRISMA extension for scoping reviews (PRISMA-ScR) checklist were used to document the review process. The McMaster critical review checklist was used to determine the quality of the included studies. Thematic analyses were conducted using NVivo version 12. Results: Three studies showed evidence on the impact of COVID-19 and family planning services, six studies reported on maternal and child services and eleven studies reported on sexual health (sexual behavior). Limited access to family planning use, reduction in multiple sexual partnership, decreased transactional sex, and maternal and child services disruption were some impacts reported in the included studies. Conclusion: This study has demonstrated the impacts of COVID-19 on family planning access, multiple sexual partnership, transactional sex, and disruption of maternal and child health services. Interventions that will consider the immediate availability of and access to all sexual and reproductive health services should be prioritized
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