Experimental tests of reaction rate theory: Mu+H2 and Mu+D2

Copyright @ 1987 American Institute of Physics.Bimolecular rate constants for the thermal chemical reactions of muonium (Mu) with hydrogen and deuterium—Mu+H2→MuH+H and Mu+D2→MuD+D—over the temperature range 473–843 K are reported. The Arrhenius parameters and 1σ uncertainties for the H2 reaction are log A (cm3 molecule-1 s-1)=-9.605±0.074 and Ea =13.29±0.22 kcal mol-1, while for D2 the values are -9.67±0.12 and 14.73±0.40, respectively. These results are significantly more precise than those reported earlier by Garner et al. For the Mu reaction with H2 our results are in excellent agreement with the 3D quantum mechanical calculations of Schatz on the Liu–Siegbahn–Truhlar–Horowitz potential surface, but the data for both reactions compare less favorably with variational transition-state theory, particularly at the lower temperatures.NSERC (Canada) and the Petroleum Research Foundation of the Americal Chemical Society

Reaction kinetics of muonium with the halogen gases (F2, Cl2, and Br2)

Copyright @ 1989 American Institute of PhysicsBimolecular rate constants for the thermal chemical reactions of muonium (Mu) with the halogen gases—Mu+X2→MuX+X—are reported over the temperature ranges from 500 down to 100, 160, and 200 K for X2=F2,Cl2, and Br2, respectively. The Arrhenius plots for both the chlorine and fluorine reactions show positive activation energies Ea over the whole temperature ranges studied, but which decrease to near zero at low temperature, indicative of the dominant role played by quantum tunneling of the ultralight muonium atom. In the case of Mu+F2, the bimolecular rate constant k(T) is essentially independent of temperature below 150 K, likely the first observation of Wigner threshold tunneling in gas phase (H atom) kinetics. A similar trend is seen in the Mu+Cl2 reaction. The Br2 data exhibit an apparent negative activation energy [Ea=(−0.095±0.020) kcal mol−1], constant over the temperature range of ∼200–400 K, but which decreases at higher temperatures, indicative of a highly attractive potential energy surface. This result is consistent with the energy dependence in the reactive cross section found some years ago in the atomic beam data of Hepburn et al. [J. Chem. Phys. 69, 4311 (1978)]. In comparing the present Mu data with the corresponding H atom kinetic data, it is found that Mu invariably reacts considerably faster than H at all temperatures, but particularly so at low temperatures in the cases of F2 and Cl2. The current transition state calculations of Steckler, Garrett, and Truhlar [Hyperfine Interact. 32, 779 (986)] for Mu+X2 account reasonably well for the rate constants for F2 and Cl2 near room temperature, but their calculated value for Mu+Br2 is much too high. Moreover, these calculations seemingly fail to account for the trend in the Mu+F2 and Mu+Cl2 data toward pronounced quantum tunneling at low temperatures. It is noted that the Mu kinetics provide a crucial test of the accuracy of transition state treatments of tunneling on these early barrier HX2 potential energy surfaces.NSERC (Canada), Donors of the Petroleum Research Fund, administered by the American Chemical Society, for their partial support of this research and the Canada Council

Antiepileptic drugs for the primary and secondary prevention of seizures after intracranial venous thrombosis

Reviewpublished_or_final_versio

Antiepileptic drugs for the primary and secondary prevention of seizures after intracranial venous thrombosis

BACKGROUND: Intracranial venous thrombosis (ICVT) commonly presents with seizures in the acute period, and some people may develop recurrent seizures in the long term. The prophylactic use of antiepileptic drugs (AEDs) for the management of post-ICVT seizures is controversial, and there is currently no consensus on the optimal management of post-ICVT seizures. This is an updated version of the original Cochrane review published in The Cochrane Library 2006, Issue 3. OBJECTIVES: To assess the effects of AEDs for the primary and secondary prevention of seizures related to ICVT.(1) For the question of primary prevention, we aimed to examine whether AEDs reduce the likelihood of seizures in people who have had an ICVT but have not had a seizure.(2) For the question of secondary prevention, we aimed to examine whether AEDs reduce the likelihood of further seizures in people who have had an ICVT and at least one seizure. SEARCH METHODS: We aimed to identify relevant studies in the Cochrane Epilepsy Group and Cochrane Stroke Group Specialised Registers. We also undertook specialised searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library 2013, Issue 7) and MEDLINE (Ovid 1946 to 22 August 2013) and checked the reference lists of articles retrieved from the searches. SELECTION CRITERIA: We considered all randomised and quasi-randomised controlled trials in which participants were assigned to a treatment group (that is, receiving at least one AED) or control group (receiving placebo or no drug). DATA COLLECTION AND ANALYSIS: Both review authors independently screened and assessed the methodological quality of the studies. If studies had been included in the review, then one review author would have extracted the data and the other would have checked the extracted data. MAIN RESULTS: No relevant studies were found. AUTHORS' CONCLUSIONS: There is no evidence to support or refute the use of antiepileptic drugs for the primary or secondary prevention of seizures related to intracranial venous thrombosis. Well-designed randomised controlled trials are urgently needed to inform practice. Since the last version of this review no new studies have been found.published_or_final_versio

El Índice Cartera Vencida como Medida de Riesgo de Crédito: Análisis y Aplicación al Caso de Chile

This paper proposes the non-performing loans (NPL) ratio, defined as the change in the stock of NPL adjusted by write-offs and standardized by loans, as the main measure to be used for modeling the credit risk of the Chilean banking system. In particular, the paper identifies certain statistical and conceptual advantages of this measure with respect to loan loss provisions (LLP), which support this idea. First, the NPL ratio by type of credit covers a greater time span than LLP. Second, the forward-looking nature of LLP –one of its main advantages over the NPL ratio– is applicable only from 2004 onward due to various changes in Chilean reporting standards. Third, LLP is discretionary because provisioning is made on the basis of relative risk aversion of banks. Fourth, the NPL ratio produces smoother series than LLP for consumer and mortgage loans. In addition, the dynamic structure observed in both time series does not differ significantly. The econometric model estimated for the period January 1997 to June 2010 shows that the NPL ratio has statistically significant relations with macroeconomic aggregates such as the annual output growth, the short and long term interest rates, the annual inflation rate, the peso-dollar exchange rate, and the surprises in credit growth. Finally, the out-of-sample forecasts indicate differences between the actual and projected NPL ratios that are economically significant only in the case of mortgage credit. For the remaining portfolios, the evolution of this ratio during the period of July 2008 to June 2010 does not differ significantly from that predicted by the econometric model.

Investigación, políticas y desarrollo en el Perú

El propósito de este trabajo es analizar la siguiente proposición: las diferencias en la calidad de vida y, más específicamente, las que afectan el desarrollo psicobiológico entre los 0 y los 5 años de edad de niñas, niños y adolescentes en el Perú, contribuyen a la variación de sus logros educativos. Nos motiva la preocupación ante el riesgo de que la actual situación socioeconómica del Perú —y, concretamente, la extensión de la pobreza crónica— afecte el desarrollo infantil de forma tal que interfiera con los fines del sistema educativo estatal.Child development, Academic achievement, Education, Peru

Coupled BE/FE/BE approach for scattering from fluid-filled structures

NASHUA is a coupled finite element/boundary element capability built around NASTRAN for calculating the low frequency far-field acoustic pressure field radiated or scattered by an arbitrary, submerged, three-dimensional, elastic structure subjected to either internal time-harmonic mechanical loads or external time-harmonic incident loadings. Described here are the formulation and use of NASHUA for solving such structural acoustics problems when the structure is fluid-filled. NASTRAN is used to generate the structural finite element model and to perform most of the required matrix operations. Both fluid domains are modeled using the boundary element capability in NASHUA, whose matrix formulation (and the associated NASTRAN DMAP) for evacuated structures can be used with suitable interpretation of the matrix definitions. After computing surface pressures and normal velocities, far-field pressures are evaluated using an asymptotic form of the Helmholtz exterior integral equation. The proposed numerical approach is validated by comparing the acoustic field scattered from a submerged fluid-filled spherical thin shell to that obtained with a series solution, which is also derived here

Porcine circovirus 3 is highly prevalent in serum and tissues and may persistently infect wild boar (Sus scrofa scrofa)

Porcine circovirus 3 (PCV‐3) prevalence has been minimally investigated in wild boar; dynamics of infection and viral tissue distribution are currently unknown. In this study, serum samples from 518 wild boar (from years 2004 to 2018) were used to study frequency of infection. Also, serum samples from 19 boar captured and recaptured at least two times for a period of time from 1 month to 1 year were collected to determine PCV‐3 infection dynamics. Finally, to elucidate PCV‐3 DNA organic distribution, sera, different tissues and faeces were obtained from 35 additional wild boar. PCV‐3 DNA was extracted and amplified with a conventional PCR. For the PCV‐3 PCR‐positive sera from the longitudinally sampled and different tissue types, a quantitative PCR was performed. Genome sequence was obtained from a number of PCV‐3 PCR‐positive samples from different years, different time‐points of infection and tissues. Obtained results confirmed the susceptibility of wild boar to the virus, showing high frequency of PCV‐3 detection (221 out of 518, 42.66%) and demonstrating circulation at least since 2004. Compiled data indicate the possibility of long‐term infections, since 5 out of 10 PCV‐3 PCR‐positive boars longitudinally sampled showed positivity in samplings separated for more than 5 months. All tested tissue types' harboured PCV‐3 genome, with the highest percentage of PCR positivity in submandibular lymph node, tonsil, lung, liver, spleen and kidney. The amount of DNA in all tested PCV‐3 PCR‐positive samples was moderate to low. All partial and complete PCV‐3 sequences obtained from wild boar displayed high nucleotide identity, higher than 98%. In conclusion, this study further confirms that wild boar is susceptible to PCV‐3 infection, showing high frequency of detection in this animal species. Furthermore, PCV‐3 can be found in different tissues of wild boar and is apparently able to cause persistent infection.Instituto Nacional de Investigación y Tecnologia Agraria y Alimentaria. Grant Number: E‐RTA2017‐00007‐00‐0