3,848 research outputs found

    Characterisation of the genetic diversity of Brucella by multilocus sequencing

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    <p>Abstract</p> <p>Background</p> <p><it>Brucella </it>species include economically important zoonotic pathogens that can infect a wide range of animals. There are currently six classically recognised species of <it>Brucella </it>although, as yet unnamed, isolates from various marine mammal species have been reported. In order to investigate genetic relationships within the group and identify potential diagnostic markers we have sequenced multiple genetic loci from a large sample of <it>Brucella </it>isolates representing the known diversity of the genus.</p> <p>Results</p> <p>Nine discrete genomic loci corresponding to 4,396 bp of sequence were examined from 160 <it>Brucella </it>isolates. By assigning each distinct allele at a locus an arbitrary numerical designation the population was found to represent 27 distinct sequence types (STs). Diversity at each locus ranged from 1.03–2.45% while overall genetic diversity equated to 1.5%. Most loci examined represent housekeeping gene loci and, in all but one case, the ratio of non-synonymous to synonymous change was substantially <1. Analysis of linkage equilibrium between loci indicated a strongly clonal overall population structure. Concatenated sequence data were used to construct an unrooted neighbour-joining tree representing the relationships between STs. This shows that four previously characterized classical <it>Brucella </it>species, <it>B. abortus</it>, <it>B. melitensis</it>, <it>B. ovis </it>and <it>B. neotomae </it>correspond to well-separated clusters. With the exception of biovar 5, <it>B. suis </it>isolates cluster together, although they form a more diverse group than other classical species with a number of distinct STs corresponding to the remaining four biovars. <it>B. canis </it>isolates are located on the same branch very closely related to, but distinguishable from, <it>B. suis </it>biovar 3 and 4 isolates. Marine mammal isolates represent a distinct, though rather weakly supported, cluster within which individual STs display one of three clear host preferences.</p> <p>Conclusion</p> <p>The sequence database provides a powerful dataset for addressing ongoing controversies in <it>Brucella </it>taxonomy and a tool for unambiguously placing atypical, phenotypically discordant or newly emerging <it>Brucella </it>isolates. Furthermore, by using the phylogenetic backbone described here, robust and rationally selected markers for use in diagnostic assay development can be identified.</p

    Evaluation of sex differences in health-related quality of life outcomes associated with child abuse: Results from the Ontario Child Health Study

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    Aims. Despite the advances in child maltreatment research, there is still the need for comprehensive information about how abuse affects a broad range of categories of young adult functioning, and the extent to which these vary by sex. We examined the associations between child physical abuse (PA) and sexual abuse (SA) and six areas of functioning (mental health, physical health, life satisfaction, illegal substance use, alcohol problems and daily smoking). Methods. Data were obtained from the 1983 Ontario Child Health Study and follow-up in 2000/2001 (n = 1893). Multilevel regression estimated the adjusted associations for PA (with severity) and SA with each of the outcomes. Estimates with an entire sample were presented with sex-by-abuse interactions to examine sex differences and then presented separately by sex. Results. In the adjusted model, severe PA and SA were associated with impairment in mental health, and both forms of PA (severe and non-severe) and SA were associated with low life satisfaction. In addition, severe PA was associated with illegal substance use. Child abuse variables were not associated with poor physical health, alcohol problems or smoking. Although sex-stratified analyses revealed different patterns, there was no significant sex difference in the integrated sample. Conclusions. This is among the first community-based studies to show a strong association between child PA and SA and low life satisfaction in young adults. The abuse effects were similar for both sexes

    Progress toward a 30 percent-efficient, monolithic, three-junction, two-terminal concentrator solar cell for space applications

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    Component efficiencies of 0.2/sq cm cells at approximately 100x AMO light concentration and 80 C temperatures are not at 15.3 percent for a 1.9 eV AlGaAs top cell, 9.9 percent for a 1.4 eV GaAs middle cell under a 1.9 eV AlGaAs filter, and 2.4 percent for a bottom 1.0 eV InGaAs cell under a GaAs substrate. The goal is to continue improvement in these performance levels and to sequentially grow these devices on a single substrate to give 30 percent efficient, monolithic, two-terminal, three-junction space concentrator cells. The broad objective is a 30 percent efficient monolithic two-terminal cell that can operate under 25 to 100x AMO light concentrations and at 75 to 100 C cell temperatures. Detailed modeling predicts that this requires three junctions. Two options are being pursued, and both use a 1.9 eV AlGaAs top junction and a 1.4 eV GaAs middle junction grown by a 1 atm OMVPE on a lattice matched substrate. Option 1 uses a low-doped GaAs substrate with a lattice mismatched 1.0 eV InGaAs cell formed on the back of the substrate. Option 2 uses a Ge substrate to which the AlGaAs and GaAs top junctions are lattice matched, with a bottom 0.7 eV Ge junction formed near the substrate interface with the GaAs growth. The projected efficiency contributions are near 16, 11, and 3 percent, respectively, from the top, middle, and bottom junctions

    Is copyright blind to the visual?

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    This article argues that, with respect to the copyright protection of works of visual art, the general uneasiness that has always pervaded the relationship between copyright law and concepts of creativity produces three anomalous results. One of these is that copyright lacks much in the way of a central concept of 'visual art' and, to the extent that it embraces any concept of the 'visual', it is rooted in the rhetorical discourse of the Renaissance. This means that copyright is poorly equipped to deal with modern developments in the visual arts. Secondly, the pervasive effect of rhetorical discourse appears to have made it particularly difficult for copyright law to strike a meaningful balance between protecting creativity and permitting its use in further creative works. Thirdly, just when rhetorical discourse might have been useful in identifying the significance and materiality of the unique one-off work of visual art, copyright law chooses to ignore its implications

    The 25 percent-efficient GaAs Cassegrainian concentrator cell

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    Very high-efficiency GaAs Cassegrainian solar cells have been fabricated in both the n-p and p-n configurations. The n-p configuration exhibits the highest efficiency at concentration, the best cells having an efficiency eta of 24.5 percent (100X, AM0, temperature T = 28 C). Although the cells are designed for operation at this concentration, peak efficiency is observed near 300 suns (eta = 25.1 percent). To our knowledge, this is the highest reported solar cell efficiency for space applications. The improvement in efficiency over that reported at the previous SPRAT conference is attributed primarily to lower series resistance and improved grid-line plating procedures. Using previously measured temperature coefficients, researchers estimate that the n-p GaAs cells should deliver approximately 22.5 percent efficiency at the operating conditions of 100 suns and T = 80 C. This performance exceeds the NASA program goal of 22 percent for the Cassegrainian cell. One hundred Cassegrainian cells have been sent to NASA as deliverables, sixty-eight in the n-p configuration and thirty-two in the p-n configuration

    Mothers\u27 Experiences in the Nurse-Family Partnership Program: A Qualitative Case Study

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    BACKGROUND:Few studies have explored the experiences of low income mothers participating in nurse home visiting programs. Our study explores and describes mothers\u27 experiences participating in the Nurse-Family Partnership (NFP) Program, an intensive home visiting program with demonstrated effectiveness, from the time of program entry before 29 weeks gestation until their infant\u27s first birthday.METHODS:A qualitative case study approach was implemented. A purposeful sample of 18 low income, young first time mothers participating in a pilot study of the NFP program in Hamilton, Ontario, Canada partook in one to two face to face in-depth interviews exploring their experiences in the program. All interviews were digitally recorded and transcribed verbatim. Conventional content analysis procedures were used to analyze all interviews. Data collection and initial analysis were implemented concurrently.RESULTS:The mothers participating in the NFP program were very positive about their experiences in the program. Three overarching themes emerged from the data: 1. Getting into the NFP program; 2. The NFP nurse is an expert, but also like a friend providing support; and 3. Participating in the NFP program is making me a better parent.CONCLUSIONS:Our findings provide vital information to home visiting nurses and to planners of home visiting programs about mothers\u27 perspectives on what is important to them in their relationships with their nurses, how nurses and women are able to develop positive therapeutic relationships, and how nurses respond to mothers\u27 unique life situations while home visiting within the NFP Program. In addition our findings offer insights into why and under what circumstances low income mothers will engage in nurse home visiting and how they expect to benefit from their participation

    Twenty Years of Unrelated Donor Bone Marrow Transplantation for Pediatric Acute Leukemia Facilitated by the National Marrow Donor Program

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    AbstractThe National Marrow Donor Program (NMDP) has facilitated unrelated donor hematopoietic cell transplants for more than 20 years. In this time period, there have been many changes in clinical practice, including improvements in HLA typing and supportive care, and changes in the source of stem cells. Availability of banked unrelated donor cord blood (incorporated into the NMDP registry in 2000) as a source of stem cells has become an important option for children with leukemia, offering the advantages of immediate availability for children with high-risk disease, the need for a lesser degree of HLA match, and expanding access for those with infrequent HLA haplotypes. Overall survival (OS) in children with acute leukemia transplanted with unrelated donor bone marrow (BM) is markedly better in more recent years, largely attributable to less treatment-related mortality (TRM). Within this cohort, 2-year survival was markedly better for patients with acute lymphoblastic leukemia (ALL) in first complete response (CR1) (74%) versus second complete response (CR2) (62%) or more advanced disease (33%). Similar findings are observed with patients with AML, suggesting earlier referral to bone marrow transplant (BMT) is optimal for survival. Notably, this improvement over time was not observed in unmodified peripheral blood stem cell (PBSC) recipients, suggesting unmodified PBSC may not be the optimal stem cell source for children
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