309 research outputs found

    Is technical analysis in the foreign exchange market profitable? a genetic programming approach

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    Using genetic programming techniques to find technical trading rules, we find strong evidence of economically significant out-of-sample excess returns to those rules for each of six exchange rates, over the period 1981-1995. Further, when the dollar/deutschemark rules are allowed to determine trades in the other markets, there is a significant improvement in performance in all cases, except for the deutschemark/yen. Betas calculated for the returns according to various benchmark portfolios provide no evidence that the returns to these rules are compensation for bearing systematic risk. Bootstrapping results on the dollar/deutschemark indicate that the trading rules are detecting patterns in the data that are not captured by standard statistical models.Programming (Mathematics) ; Foreign exchange

    The BsaHI restriction-modification system: Cloning, sequencing and analysis of conserved motifs

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    <p>Abstract</p> <p>Background</p> <p>Restriction and modification enzymes typically recognise short DNA sequences of between two and eight bases in length. Understanding the mechanism of this recognition represents a significant challenge that we begin to address for the BsaHI restriction-modification system, which recognises the six base sequence GRCGYC.</p> <p>Results</p> <p>The DNA sequences of the genes for the BsaHI methyltransferase, bsaHIM, and restriction endonuclease, bsaHIR, have been determined (GenBank accession <ext-link ext-link-type="gen" ext-link-id="#EU386360">#EU386360</ext-link>), cloned and expressed in <it>E. coli</it>. Both the restriction endonuclease and methyltransferase enzymes share significant similarity with a group of 6 other enzymes comprising the restriction-modification systems HgiDI and HgiGI and the putative HindVP, NlaCORFDP, NpuORFC228P and SplZORFNP restriction-modification systems. A sequence alignment of these homologues shows that their amino acid sequences are largely conserved and highlights several motifs of interest. We target one such conserved motif, reading SPERRFD, at the C-terminal end of the bsaHIR gene. A mutational analysis of these amino acids indicates that the motif is crucial for enzymatic activity. Sequence alignment of the methyltransferase gene reveals a short motif within the target recognition domain that is conserved among enzymes recognising the same sequences. Thus, this motif may be used as a diagnostic tool to define the recognition sequences of the cytosine C5 methyltransferases.</p> <p>Conclusion</p> <p>We have cloned and sequenced the BsaHI restriction and modification enzymes. We have identified a region of the R. BsaHI enzyme that is crucial for its activity. Analysis of the amino acid sequence of the BsaHI methyltransferase enzyme led us to propose two new motifs that can be used in the diagnosis of the recognition sequence of the cytosine C5-methyltransferases.</p

    Assessing precipitation from a dual-polarisation X-band radar campaign using the Grid-to-Grid hydrological model

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    A set of Quantitative Precipitation Estimates (QPEs) from a dual-polarisation X-band radar observation campaign in a mountainous area of Northern Scotland is assessed with reference to observed river flows as well as being compared to estimates from the UK C-band radar and raingauge networks. Employing estimation methods of varying complexity, the X-band QPEs are trialled as alternative inputs to Grid-to-Grid (G2G), a distributed hydrological model, to produce simulated river flows for comparison with observations. This hydrological assessment complements and extends a previous meteorological assessment that used point raingauge data only. Precipitation estimates for two periods over the observation campaign in 2016 (March to April and June to August) are assessed. During the second period, increased incorporation of dual-polarisation variables into the radar processing chain is found to be of considerable benefit, whereas during the first period the low height of the melting layer often restricts their use. As a result of the complex topography in Northern Scotland, the Lowest Usable Elevation (LUE) of the X-band radar observations is found to be a stronger indicator of the hydrological model performance than range from the radar. For catchments with an LUE of less than 3 km, the best X-band QPE typically performs better for modelling river flow than using an estimate from the UK C-band radar network. The hydrological assessment framework used here brings fresh insights into the performance of the different QPEs, as well as providing a stimulus for targeted improvements to dual-polarisation radar-based QPEs that have wider relevance beyond the case study situation

    Predictors of Ventriculostomy Infection in a Large Cohort

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    Introduction: External ventricular drains (EVDs) are neurosurgical devices used to treat hydrocephalus and monitor intracranial pressure. Ventriculostomy-associated infections (VAIs) are a complication of EVD placement associated with increased morbidity and mortality, as well as cost. A previous study at Jefferson reported a decrease in VAI’s with the use of antibiotic-coated catheters. Objective: The aim of this study was to assess the current rate of VAI’s and determine risk factors associated with infections. Methods: Using Epic, the electronic medical records software, we conducted a retrospective review of patients who underwent EVD placement at Thomas Jefferson University Hospital and Jefferson Hospital for Neuroscience between January 2010 and January 2018. Results: During this time period, 1107 EVD’s were placed in 1034 patients. The most common indications for placement were acute subarachnoid hemorrhage (51%), intraparenchymal hemorrhage (15.4%), and brain tumors (9.7%). 38 patients suffered from a VAI, for an infection rate of 0.03%. Patients with VAI’s had a significantly longer duration of EVD placement (19.4 vs. 11.1 days). Risk factors for VAI included CSF leak (OR 2.35), EVD placement greater than 11 days (OR 2.14), and concurrent infection (OR 1.74). There was no association with patient age, sex, initial diagnosis, drain replacement, number of samples drawn, or prophylactic antibiotics. Discussion: Despite the use of antibiotic-coated catheters, VAI’s still remain a prevalent complication of EVD placement. By working to prevent CSF leaks, minimize the duration of EVD placement, and appropriately treat concurrent infections, it may be possible to further lower VAI rates

    Innate Immune Cell Recovery Is Positively Regulated by NLRP12 during Emergency Hematopoiesis

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    With enhanced concerns of terrorist attacks, dual exposure to radiation and thermal combined injury (RCI) has become a real threat with devastating immunosuppression. NLRP12, a member of the NOD-like receptor family, is expressed in myeloid and bone marrow cells and has been implicated as a checkpoint regulator of inflammatory cytokines as well as an inflammasome activator. We show that NLRP12 has a profound impact on hematopoietic recovery during RCI by serving as a checkpoint of TNF signaling and preventing hematopoietic apoptosis. Using a mouse model of RCI, increased NLRP12 expression was detected in target tissues. Nlrp12−/− mice exhibited significantly greater mortality, inability to fight bacterial infection, heightened levels of pro-inflammatory cytokines, overt granulocyte/monocyte progenitor cell apoptosis and failure to reconstitute peripheral myeloid populations. Anti-TNF antibody administration improved peripheral immune recovery. These data suggest that NLRP12 is essential for survival after RCI by regulating myelopoiesis and immune reconstitution

    Functional Modularity of the Arginine Catabolic Mobile Element Contributes to the Success of USA300 Methicillin-Resistant Staphylococcus aureus

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    The successful USA300 Community-Associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) lineage predominantly causes skin and soft tissue infections (SSTIs) and is highly associated with carriage of the Arginine Catabolic Mobile Element (ACME). However, the contribution of ACME to USA300 fitness during SSTIs remains incompletely understood. We show that the constitutive ACME-encoded arginine-deiminase system (Arc) allows USA300 to thrive in acidic environments that mimic human skin. Consequently, ACME-Arc drives excessive production of host polyamines, compounds uniquely toxic to S. aureus. To mitigate this, ACME also encodes SpeG, a polyamine-resistance enzyme that is essential for combating excess host polyamines in a murine SSTI model. Inhibiting host polyamine production not only restored ΔspeG persistence within infected wounds but also severely altered the host healing process, implying that polyamines play integral roles in coordinating the wound-healing response. Together, these data underscore the functional modularity of ACME and its contribution to the success of USA300 CA-MRSA

    Flagellin Treatment Prevents Increased Susceptibility to Systemic Bacterial Infection after Injury by Inhibiting Anti-Inflammatory IL-10+ IL-12- Neutrophil Polarization

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    Severe trauma renders patients susceptible to infection. In sepsis, defective bacterial clearance has been linked to specific deviations in the innate immune response. We hypothesized that innate immune modulations observed during sepsis also contribute to increased bacterial susceptibility after severe trauma. A well-established murine model of burn injury, used to replicate infection following trauma, showed that wound inoculation with P. aeruginosa quickly spreads systemically. The systemic IL-10/IL-12 axis was skewed after burn injury with infection as indicated by a significant elevation in serum IL-10 and polarization of neutrophils into an anti-inflammatory (“N2”; IL-10+ IL-12−) phenotype. Infection with an attenuated P. aeruginosa strain (ΔCyaB) was cleared better than the wildtype strain and was associated with an increased pro-inflammatory neutrophil (“N1”; IL-10−IL-12+) response in burn mice. This suggests that neutrophil polarization influences bacterial clearance after burn injury. Administration of a TLR5 agonist, flagellin, after burn injury restored the neutrophil response towards a N1 phenotype resulting in an increased clearance of wildtype P. aeruginosa after wound inoculation. This study details specific alterations in innate cell populations after burn injury that contribute to increased susceptibility to bacterial infection. In addition, for the first time, it identifies neutrophil polarization as a therapeutic target for the reversal of bacterial susceptibility after injury

    Positive psychology of Malaysian students: impacts of engagement, motivation, self-compassion and wellbeing on mental health

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    Malaysia plays a key role in education of the Asia Pacific, expanding its scholarly output rapidly. However, mental health of Malaysian students is challenging, and their help-seeking is low because of stigma. This study explored the relationships between mental health and positive psychological constructs (academic engagement, motivation, self-compassion, and wellbeing), and evaluated the relative contribution of each positive psychological construct to mental health in Malaysian students. An opportunity sample of 153 students completed the measures regarding these constructs. Correlation, regression, and mediation analyses were conducted. Engagement, amotivation, self-compassion, and wellbeing were associated with, and predicted large variance in mental health. Self-compassion was the strongest independent predictor of mental health among all the positive psychological constructs. Findings can imply the strong links between mental health and positive psychology, especially selfcompassion. Moreover, intervention studies to examine the effects of self-compassion training on mental health of Malaysian students appear to be warranted.N/
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