Automatic detection of discordant outliers via the Ueda's method

The importance of identifying outliers in a data set is well known. Although variousoutlier detection methods have been proposed in order to enable reliable inferencesregarding a data set, a simple but less known method has been proposed by Ueda(1996/2009). Since this new method, called Uedas method, has not been systematicallyanalysed in previous research, a simulation study addressing its performance androbustness is presented. Although the method was derived assuming that theunderlying data is normally distributed, its performance was analysed using data fromvarious outlier-prone distributions commonly found in several research fields. Theresults obtained enable us to define the strengths and weaknesses of the methodalong with its limits of applicability. Furthermore, an unforeseen field of application ofthe method, which requires further studies was also identified

The effect of the sixth sulfur ligand in the catalytic mechanism of periplasmic nitrate reductase

The catalytic mechanism of nitrate reduction by periplasmic nitrate reductases has been investigated using theoretical and computational means. We have found that the nitrate molecule binds to the active site with the Mo ion in the +6 oxidation state. Electron transfer to the active site occurs only in the proton-electron transfer stage, where the MoV species plays an important role in catalysis. The presence of the sulfur atom in the molybdenum coordination sphere creates a pseudo-dithiolene ligand that protects it from any direct attack from the solvent. Upon the nitrate binding there is a conformational rearrangement of this ring that allows the direct contact of the nitrate with MoVI ion. This rearrangement is stabilized by the conserved methionines Met141 and Met308. The reduction of nitrate into nitrite occurs in the second step of the mechanism where the two dimethyl-dithiolene ligands have a key role in spreading the excess of negative charge near the Mo atom to make it available for the chemical reaction. The reaction involves the oxidation of the sulfur atoms and not of the molybdenum as previously suggested. The mechanism involves a molybdenum and sulfur-based redox chemistry instead of the currently accepted redox chemistry based only on the Mo ion. The second part of the mechanism involves two protonation steps that are promoted by the presence of MoV species. MoVI intermediates might also be present in this stage depending on the availability of protons and electrons. Once the water molecule is generated only the MoVI species allow water molecule dissociation, and, the concomitant enzymatic turnover.Fil: Cerqueira, N.M.F.S.A.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Gonzalez, P.J.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Brondino, Carlos Dante. Universidad Nacional del Litoral; ArgentinaFil: Romão, M.J.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Romão, C.C.. Instituto de Tecnologia Qu&Fil: Moura, I.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; PortugalFil: Moura, J.J.G.. Faculdade de Ciências E Tecnologia, Universidade Nova de Lisboa; Portuga

Protecting police officers against burnout: Overcoming a fragmented research field

This study aims to identify the determinants of burnout in police officers. We considered a wide range of psychosocial risk factors, individual variables that have been previously found to be associated with burnout in police officers (affective and cognitive empathy, self-care), and variables whose unique impact on burnout of police officers needs further clarification (organizational justice and organizational identification). The study was conducted in Portugal, and the sample was constituted by 573 members of the National Republican Guard (GNR—Guarda Nacional Republicana). The participants were invited to answer an online anonymous survey, which included previously validated measures of the following variables: burnout (exhaustion and disengagement), psychosocial risk factors, self-care, empathy (cognitive and affective), organizational justice, and organizational identification. Furthermore, we controlled for the potential impact of demographic variables (age, gender, years of professional experience, religiosity, political orientation, and income). Multiple regression analysis showed that when taken together, only a few of the variables associated with burnout had a unique impact on both exhaustion and disengagement: quantitative demands and affective empathy were burnout risk factors; meaningful work, organizational justice (distributive justice, procedural justice, and interactional justice), and organizational identification were burnout protective factors. Our results highlight the importance of developing theoretical models and planning interventions to prevent burnout in police officers, focusing mainly on the above-mentioned variables.info:eu-repo/semantics/publishedVersio

Slow Schroedinger dynamics of gauged vortices

Multivortex dynamics in Manton's Schroedinger--Chern--Simons variant of the Landau-Ginzburg model of thin superconductors is studied within a moduli space approximation. It is shown that the reduced flow on M_N, the N vortex moduli space, is hamiltonian with respect to \omega_{L^2}, the L^2 Kaehler form on \M_N. A purely hamiltonian discussion of the conserved momenta associated with the euclidean symmetry of the model is given, and it is shown that the euclidean action on (M_N,\omega_{L^2}) is not hamiltonian. It is argued that the N=3 flow is integrable in the sense of Liouville. Asymptotic formulae for \omega_{L^2} and the reduced Hamiltonian for large intervortex separation are conjectured. Using these, a qualitative analysis of internal 3-vortex dynamics is given and a spectral stability analysis of certain rotating vortex polygons is performed. Comparison is made with the dynamics of classical fluid point vortices and geostrophic vortices.Comment: 22 pages, 2 figure

On the curvature of vortex moduli spaces

We use algebraic topology to investigate local curvature properties of the moduli spaces of gauged vortices on a closed Riemann surface. After computing the homotopy type of the universal cover of the moduli spaces (which are symmetric powers of the surface), we prove that, for genus g>1, the holomorphic bisectional curvature of the vortex metrics cannot always be nonnegative in the multivortex case, and this property extends to all Kaehler metrics on certain symmetric powers. Our result rules out an established and natural conjecture on the geometry of the moduli spaces.Comment: 25 pages; final version, to appear in Math.

A non-randomized study in consecutive patients with postcholecystectomy refractory biliary leaks who were managed endoscopically with the use of multiple plastic stents or fully covered self-expandable metal stents (with videos).

BACKGROUND: Endoscopic management of postcholecystectomy biliary leaks is widely accepted as the treatment of choice. However, refractory biliary leaks after a combination of biliary sphincterotomy and the placement of a large-bore (10F) plastic stent can occur, and the optimal rescue endotherapy for this situation is unclear. OBJECTIVE: To compare the clinical effectiveness of the use of a fully covered self-expandable metal stent (FCSEMS) with the placement of multiple plastic stents (MPS) for the treatment of postcholecystectomy refractory biliary leaks. DESIGN: Prospective study. SETTING: Two tertiary-care referral academic centers and one general district hospital. PATIENTS: Forty consecutive patients with refractory biliary leaks who underwent endoscopic management. INTERVENTIONS: Temporary placement of MPS (n = 20) or FCSEMSs (n = 20). MAIN OUTCOME MEASUREMENTS: Clinical outcomes of endotherapy as well as the technical success, adverse events, need for reinterventions, and prognostic factors for clinical success. RESULTS: Endotherapy was possible in all patients. After endotherapy, closure of the leak was accomplished in 13 patients (65%) who received MPS and in 20 patients (100%) who received FCSEMSs (P = .004). The Kaplan-Meier (log-rank) leak-free survival analysis showed a statistically significant difference between the 2 patient populations (χ2 [1] = 8.30; P < .01) in favor of the FCSEMS group. Use of <3 plastic stents (P = .024), a plastic stent diameter <20F (P = .006), and a high-grade biliary leak (P = .015) were shown to be significant predictors of treatment failure with MPS. The 7 patients in whom placement of MPS failed were retreated with FCSEMSs, resulting in closure of the leaks in all cases. LIMITATIONS: Non-randomized design. CONCLUSION: In our series, the results of the temporary placement of FCSEMSs for postcholecystectomy refractory biliary leaks were superior to those from the use of MPS. A randomized study is needed to confirm our results before further recommendations

Metabolic composition of the cyanobacterium Nostoc muscorum as a function of culture time: a 1H NMR metabolomics study

Cyanobacteria are considered a factory of added-value compounds. However, knowledge about the array of interesting compounds that could be extracted from these prokaryotic organisms is still very limited. Nuclear Magnetic Resonance (NMR) spectroscopy is a widely used technique for metabolic profiling that allows an overview of the main metabolites present in complex biological matrices. In this work, high resolution 1H NMR was employed to screen the metabolic composition of the freshwater cyanobacterium Nostoc muscorum. This species showed high longevity, being able to grow for more than one hundred days without any medium supplementation. During the period of study, several interesting metabolites were detected, such as several sugars and oligosaccharides, lipids (e.g., glycolipids, ω-3 and ω-6 fatty acids), amino acids, including mycosporin-like, peptides, and pigments (e.g., chlorophyll a and carotenoids). Owing to the long-term monitoring implemented in this study, the production of these compounds could be associated to specific moments of the growth of N. muscorum, providing new insights into the most appropriate harvesting time points for the biotechnological exploitation of specific molecules.publishe

Pre-operative predictors of red blood cell transfusion in liver transplantation

info:eu-repo/semantics/publishedVersio