693 research outputs found

    Polynomial diffeomorphisms of C^2, IV: The measure of maximal entropy and laminar currents

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    This paper concerns the dynamics of polynomial automorphisms of C2{\bf C}^2. One can associate to such an automorphism two currents μ±\mu^\pm and the equilibrium measure μ=μ+μ\mu=\mu^+\wedge\mu^-. In this paper we study some geometric and dynamical properties of these objects. First, we characterize μ\mu as the unique measure of maximal entropy. Then we show that the measure μ\mu has a local product structure and that the currents μ±\mu^\pm have a laminar structure. This allows us to deduce information about periodic points and heteroclinic intersections. For example, we prove that the support of μ\mu coincides with the closure of the set of saddle points. The methods used combine the pluripotential theory with the theory of non-uniformly hyperbolic dynamical systems

    Mapping Patent Classifications: Portfolio and Statistical Analysis, and the Comparison of Strengths and Weaknesses

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    The Cooperative Patent Classifications (CPC) jointly developed by the European and US Patent Offices provide a new basis for mapping and portfolio analysis. This update provides an occasion for rethinking the parameter choices. The new maps are significantly different from previous ones, although this may not always be obvious on visual inspection. Since these maps are statistical constructs based on index terms, their quality--as different from utility--can only be controlled discursively. We provide nested maps online and a routine for portfolio overlays and further statistical analysis. We add a new tool for "difference maps" which is illustrated by comparing the portfolios of patents granted to Novartis and MSD in 2016.Comment: Scientometrics 112(3) (2017) 1573-1591; http://link.springer.com/article/10.1007/s11192-017-2449-

    Behavior and Impact of Zirconium in the Soil–Plant System: Plant Uptake and Phytotoxicity

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    Because of the large number of sites they pollute, toxic metals that contaminate terrestrial ecosystems are increasingly of environmental and sanitary concern (Uzu et al. 2010, 2011; Shahid et al. 2011a, b, 2012a). Among such metals is zirconium (Zr), which has the atomic number 40 and is a transition metal that resembles titanium in physical and chemical properties (Zaccone et al. 2008). Zr is widely used in many chemical industry processes and in nuclear reactors (Sandoval et al. 2011; Kamal et al. 2011), owing to its useful properties like hardness, corrosion-resistance and permeable to neutrons (Mushtaq 2012). Hence, the recent increased use of Zr by industry, and the occurrence of the Chernobyl and Fukashima catastrophe have enhanced environmental levels in soil and waters (Yirchenko and Agapkina 1993; Mosulishvili et al. 1994 ; Kruglov et al. 1996)

    A Schistosome cAMP-Dependent Protein Kinase Catalytic Subunit Is Essential for Parasite Viability

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    Eukaryotes, protozoan, and helminth parasites make extensive use of protein kinases to control cellular functions, suggesting that protein kinases may represent novel targets for the development of anti-parasitic drugs. Because of their central role in intracellular signaling pathways, cyclic nucleotide–dependent kinases such as cAMP-dependent protein kinase (PKA) represent promising new targets for the treatment of parasitic infections and neoplastic disorders. However, the role of these kinases in schistosome biology has not been characterized and the genes encoding schistosome PKAs have not been identified. Here we provide biochemical evidence for the presence of a PKA signaling pathway in adult Schistosoma mansoni and show that PKA activity is required for parasite viability in vitro. We also provide the first full description of a gene that encodes a PKA catalytic subunit in S. mansoni, named SmPKA-C. Finally we demonstrate, through RNA interference, that SmPKA-C contributes to the PKA activity we detected biochemically and that inhibition of SmPKA-C expression in adult schistosomes results in parasite death. Together our data show that SmPKA-C is a critically important gene product and may represent an attractive therapeutic target for the treatment and control of schistosomiasis

    Acceptability of the 6-PACK falls prevention program: A pre-implementation study in hospitals participating in a cluster randomized controlled trial

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    There is limited evidence to support the effectiveness of falls prevention interventions in the acute hospital setting. The 6-PACK falls prevention program includes a fall-risk tool; 'falls alert' signs; supervision of patients in the bathroom; ensuring patients' walking AIDS are within reach; toileting regimes; low-low beds; and bed/chair alarms. This study explored the acceptability of the 6-PACK program from the perspective of nurses and senior staff prior to its implementation in a randomised controlled trial. A mixed-methods approach was applied involving 24 acute wards from six Australian hospitals. Participants were nurses working on participating wards and senior hospital staff including: Nurse Unit Managers; senior physicians; Directors of Nursing; and senior personnel involved in quality and safety or falls prevention. Information on program acceptability (suitability, practicality and benefits) was obtained by surveys, focus groups and interviews. Survey data were analysed descriptively, and focus group and interview data thematically. The survey response rate was 60%. Twelve focus groups (n = 96 nurses) and 24 interviews with senior staff were conducted. Falls were identified as a priority patient safety issue and nurses as key players in falls prevention. The 6-PACK program was perceived to offer practical benefits compared to current practice. Nurses agreed fall-risk tools, low-low beds and alert signs were useful for preventing falls (>70%). Views were mixed regarding positioning patients' walking aid within reach. Practical issues raised included access to equipment; and risk of staff injury with low-low bed use. Bathroom supervision was seen to be beneficial, however not always practical. Views on the program appropriateness and benefits were consistent across nurses and senior staff. Staff perceived the 6-PACK program as suitable, practical and beneficial, and were open to adopting the program. Some practical concerns were raised highlighting issues to be addressed by the implementation plan

    Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

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    Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

    Striving to promote male involvement in maternal health care in rural and urban settings in Malawi - a qualitative study

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    <p>Abstract</p> <p>Background</p> <p>Understanding the strategies that health care providers employ in order to invite men to participate in maternal health care is very vital especially in today's dynamic cultural environment. Effective utilization of such strategies is dependent on uncovering the salient issues that facilitate male participation in maternal health care. This paper examines and describes the strategies that were used by different health care facilities to invite husbands to participate in maternal health care in rural and urban settings of southern Malawi.</p> <p>Methods</p> <p>The data was collected through in-depth interviews from sixteen of the twenty health care providers from five different health facilities in rural and urban settings of Malawi. The health facilities comprised two health centres, one district hospital, one mission hospital, one private hospital and one central hospital. A semi-structured interview guide was used to collect data from health care providers with the aim of understanding strategies they used to invite men to participate in maternal health care.</p> <p>Results</p> <p>Four main strategies were used to invite men to participate in maternal health care. The strategies were; health care provider initiative, partner notification, couple initiative and community mobilization. The health care provider initiative and partner notification were at health facility level, while the couple initiative was at family level and community mobilization was at village (community) level. The community mobilization had three sub-themes namely; male peer initiative, use of incentives and community sensitization. The sustainability of each strategy to significantly influence behaviour change for male participation in maternal health care is discussed.</p> <p>Conclusion</p> <p>Strategies to invite men to participate in maternal health care were at health facility, family and community levels. The couple strategy was most appropriate but was mostly used by educated and city residents. The male peer strategy was effective and sustainable at community level. There is need for creation of awareness in men so that they sustain their participation in maternal health care activities of their female partners even in the absence of incentives, coercion or invitation.</p

    Developing a Text Messaging Risk Reduction Intervention for Methamphetamine-Using MSM: Research Note

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    Men who have sex with men (MSM) who use methamphetamine experience high risks for HIV infection due to sexual transmission behaviors often engaged in when under the influence of methamphetamine. Methamphetamine-using MSM use various forms of information technology (IT) communication such as instant messaging, social networking sites, and websites to facilitate a sexual and/or drug “hook up.” Given the acceptability of IT communication in their daily lives, an IT intervention represents an appropriate strategy to reach and intervene with out-of-treatment, methamphetamine-using MSM. The aim of this study was to conduct formative work to develop a text messaging intervention to reduce methamphetamine use and high-risk sexual behaviors among out-of-treatment MSM, which involved conducting focus groups, community partners’ meetings, and a pre-test intervention. These activities culminated in the development of a two-week, text-messaging intervention that delivered real-time electronic correspondence based on the behavioral change theories of Social Support Theory, Health Belief Model, and Social Cognitive Theory. The focus groups, community meetings, and pre-test were used to identify the IT communication device, the text messages that best support risk reduction and healthier behavioral choices, and logo, flyer and website development. The input and feedback from the target population and community partners were critical to the successful development of a culturally appropriate intervention. The knowledge gleaned from the formative work of this study will be vitally helpful in designing future IT studies

    Small-Scale Fisheries Bycatch Jeopardizes Endangered Pacific Loggerhead Turtles

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    Background. Although bycatch of industrial-scale fisheries can cause declines in migratory megafauna including seabirds, marine mammals, and sea turtles, the impacts of small-scale fisheries have been largely overlooked. Small-scale fisheries occur in coastal waters worldwide, employing over 99 % of the world’s 51 million fishers. New telemetry data reveal that migratory megafauna frequent coastal habitats well within the range of small-scale fisheries, potentially producing high bycatch. These fisheries occur primarily in developing nations, and their documentation and management are limited or non-existent, precluding evaluation of their impacts on non-target megafauna. Principal Findings/Methodology. 30 North Pacific loggerhead turtles that we satellite-tracked from 1996–2005 ranged oceanwide, but juveniles spent 70 % of their time at a high use area coincident with small-scale fisheries in Baja California Sur, Mexico (BCS). We assessed loggerhead bycatch mortality in this area by partnering with local fishers to 1) observe two small-scale fleets that operated closest to the high use area and 2) through shoreline surveys for discarded carcasses. Minimum annual bycatch mortality in just these two fleets at the high use area exceeded 1000 loggerheads year 21, rivaling that of oceanwide industrial-scale fisheries, and threatening the persistence of this critically endangered population. As a result of fisher participation in this study and a bycatch awareness campaign, a consortium of local fishers and other citizens are working to eliminate their bycatch and to establish a national loggerhea

    Dual Function of the NK Cell Receptor 2B4 (CD244) in the Regulation of HCV-Specific CD8+ T Cells

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    The outcome of viral infections is dependent on the function of CD8+ T cells which are tightly regulated by costimulatory molecules. The NK cell receptor 2B4 (CD244) is a transmembrane protein belonging to the Ig superfamily which can also be expressed by CD8+ T cells. The aim of this study was to analyze the role of 2B4 as an additional costimulatory receptor regulating CD8+ T cell function and in particular to investigate its implication for exhaustion of hepatitis C virus (HCV)-specific CD8+ T cells during persistent infection. We demonstrate that (i) 2B4 is expressed on virus-specific CD8+ T cells during acute and chronic hepatitis C, (ii) that 2B4 cross-linking can lead to both inhibition and activation of HCV-specific CD8+ T cell function, depending on expression levels of 2B4 and the intracellular adaptor molecule SAP and (iii) that 2B4 stimulation may counteract enhanced proliferation of HCV-specific CD8+ T cells induced by PD1 blockade. We suggest that 2B4 is another important molecule within the network of costimulatory/inhibitory receptors regulating CD8+ T cell function in acute and chronic hepatitis C and that 2B4 expression levels could also be a marker of CD8+ T cell dysfunction. Understanding in more detail how 2B4 exerts its differential effects could have implications for the development of novel immunotherapies of HCV infection aiming to achieve immune control
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