University of Costa Rica

About: University of Costa Rica is a education organization based out in San José, Costa Rica. It is known for research contribution in the topics: Population & Venom. The organization has 9817 authors who have published 16781 publications receiving 238208 citations. The organization is also known as: UCR & Universidad de Costa Rica.

Bulk Universality for Wigner Matrices

Abstract: We consider N × N Hermitian Wigner random matrices H where the probability density for each matrix element is given by the density ν(x) = e−U(x). We prove that the eigenvalue statistics in the bulk are given by the Dyson sine kernel provided that U ∈ C6( \input amssym $\Bbb R$) with at most polynomially growing derivatives and ν(x) ≥ Ce−C|x| for x large. The proof is based upon an approximate time reversal of the Dyson Brownian motion combined with the convergence of the eigenvalue density to the Wigner semicircle law on short scales. © 2010 Wiley Periodicals, Inc.

Studies of nucleon resonance structure in exclusive meson electroproduction

Abstract: Studies of the structure of excited baryons are key factors to the N* program at Jefferson Lab (JLab). Within the first year of data taking with the Hall B CLAS12 detector following the 12 GeV upgrade, a dedicated experiment will aim to extract the N* electrocouplings at high photon virtualities Q2. This experiment will allow exploration of the structure of N* resonances at the highest photon virtualities ever achieved, with a kinematic reach up to Q2 = 12 GeV2. This high-Q2 reach will make it possible to probe the excited nucleon structures at distance scales ranging from where effective degrees of freedom, such as constituent quarks, are dominant through the transition to where nearly massless bare-quark degrees of freedom are relevant. In this document, we present a detailed description of the physics that can be addressed through N* structure studies in exclusive meson electroproduction. The discussion includes recent advances in reaction theory for extracting N* electrocouplings from meson electropro...

Systematics of the Trichoderma harzianum species complex and the re-identification of commercial biocontrol strains

Abstract: Trichoderma harzianum is known as a cosmopolitan, ubiquitous species associated with a wide variety of substrates. It is possibly the most commonly used name in agricultural applications involving Trichoderma, including biological control of plant diseases. While various studies have suggested that T. harzianum is a species complex, only a few cryptic species are named. In the present study the taxonomy of the T. harzianum species complex is revised to include at least 14 species. Previously named species included in the complex are T. guizhouense, T. harzianum, and T. inhamatum. Two new combinations are proposed, T. lentiforme and T. lixii. Nine species are described as new, T. afarasin, T. afroharzianum, T. atrobrunneum, T. camerunense, T. endophyticum, T. neotropicale, T. pyramidale, T. rifaii and T. simmonsii. We isolated Trichoderma cultures from four commercial biocontrol products reported to contain T. harzianum. None of the biocontrol strains were identified as T. harzianum s. str. In addition, the widely applied culture 'T. harzianum T22' was determined to be T. afroharzianum. Some species in the T. harzianum complex appear to be exclusively endophytic, while others were only isolated from soil. Sexual states are rare. Descriptions and illustrations are provided. A secondary barcode, nuc translation elongation factor 1-α (TEF1) is needed to identify species in this complex.

Treatment blood pressure targets for hypertension

Abstract: Background When treating elevated blood pressure, doctors need to know what blood pressure (BP) target they should try to achieve. The standard of clinical practice for some time has been ≤ 140 - 160/ 90 - 100 mmHg. New guidelines are recommending BP targets lower than this standard. It is not known whether attempting to achieve targets lower than the standard reduces mortality and morbidity. Objectives To determine if lower BP targets (≤ 135/85 mmHg) are associated with reduction in mortality and morbidity as compared with standard BP targets (≤ 140-160/ 90-100 mmHg). Search methods Electronic search of MEDLINE (1966-2008), EMBASE (1980-2008), and CENTRAL (up to June 2008); references from review articles, clinical guidelines, and clinical trials. Selection criteria Randomized controlled trials comparing patients randomized to lower or to standard BP targets and providing data on any of the primary outcomes below. Data collection and analysis Two reviewers (JAA, MIP) independently assessed the included trials and data entry. Primary outcomes were total mortality; total serious adverse events; total cardiovascular events; myocardial infarction, stroke, congestive heart failure and end stage renal disease. Secondary outcomes were achieved mean systolic and diastolic BP and withdrawals due to adverse effects. Main results No trials comparing different systolic BP targets were found. Seven trials (22,089 subjects) comparing different diastolic BP targets were included. Despite a -4/-3 mmHg greater achieved reduction in systolic/diastolic BP, p< 0.001, attempting to achieve "lower targets" instead of "standard targets" did not change total mortality (RR 0.92, 95% CI 0.86-1.15), myocardial infarction (RR 0.90, 95% CI 0.74-1.09), stroke (RR 0.99, 95% CI 0.79-1.25) , congestive heart failure (RR 0.88, 95% CI 0.59-1.32), major cardiovascular events (RR 0.94, 95% CI 0.83-1.07), or end-stage renal disease (RR 1.01, 95% CI 0.81-1.27). The net health effect of lower targets cannot be fully assessed due to lack of information regarding all total serious adverse events and withdrawals due to adverse effects in 6 of 7 trials. A sensitivity analysis in diabetic patients and in patients with chronic renal disease also did not show a reduction in any of the mortality and morbidity outcomes with lower targets as compared to standard targets. Authors' conclusions Treating patients to lower than standard BP targets, ≤140-160/90-100 mmHg, does not reduce mortality or morbidity. Because guidelines are recommending even lower targets for diabetes mellitus and chronic renal disease, we are currently conducting systematic reviews in those groups of patients.