Time filter

Source Type

San Jose, Costa Rica

For the association football club, see Club de Futbol Universidad de Costa Rica.The University of Costa Rica is a public university in the Republic of Costa Rica, in Central America. Its main campus, Ciudad Universitaria Rodrigo Facio, is located in San Pedro Montes de Oca, in the province of San José. It is the oldest, largest, and most prestigious institution of higher learning in Costa Rica, originally established as the Universidad de Santo Tomás in 1843. It is also the most important research university in the country, and Central America. Approximately 39,000 students attend UCR throughout the year.Within the Webometrics ranking, the UCR ranks at #580 worldwide, and at #21 in Latin America. Wikipedia.

Aguero-Valverde J.,University of Costa Rica
Accident Analysis and Prevention | Year: 2013

Recently, areal models of crash frequency have being used in the analysis of various area-wide factors affecting road crashes. On the other hand, disease mapping methods are commonly used in epidemiology to assess the relative risk of the population at different spatial units. A natural next step is to combine these two approaches to estimate the excess crash frequency at area level as a measure of absolute crash risk. Furthermore, multivariate spatial models of crash severity are explored in order to account for both frequency and severity of crashes and control for the spatial correlation frequently found in crash data. This paper aims to extent the concept of safety performance functions to be used in areal models of crash frequency. A multivariate spatial model is used for that purpose and compared to its univariate counterpart. Full Bayes hierarchical approach is used to estimate the models of crash frequency at canton level for Costa Rica. An intrinsic multivariate conditional autoregressive model is used for modeling spatial random effects. The results show that the multivariate spatial model performs better than its univariate counterpart in terms of the penalized goodness-of-fit measure Deviance Information Criteria. Additionally, the effects of the spatial smoothing due to the multivariate spatial random effects are evident in the estimation of excess equivalent property damage only crashes. © 2013 Elsevier Ltd. All rights reserved. Source

Arguedas J.A.,University of Costa Rica
The Cochrane database of systematic reviews | Year: 2013

When treating elevated blood pressure (BP), doctors often want to know what blood pressure target they should try to achieve. The standard blood pressure target in clinical practice for some time has been less than 140 - 160/90 - 100 mmHg for the general population of people with elevated blood pressure. Several clinical guidelines published in recent years have recommended lower targets (less than 130/80 mmHg) for people with diabetes mellitus. It is not known whether attempting to achieve targets lower than the standard target reduces mortality and morbidity in those with elevated blood pressure and diabetes. To determine if 'lower' BP targets (any target less than 130/85 mmHg) are associated with reduction in mortality and morbidity compared with 'standard' BP targets (less than 140 - 160/90 - 100 mmHg) in people with diabetes. We searched the Database of Abstracts of Reviews of Effectiveness (DARE) and the Cochrane Database of Systematic Reviews for related reviews. We conducted electronic searches of the Hypertension Group Specialised Register (January 1946 - October 2013), the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 9), MEDLINE (January 1946 - October 2013), EMBASE (January 1974 - October 2013) and ClinicalTrials.gov. The most recent search was performed on October 4, 2013.Other search sources were the International Clinical Trials Registry Platform (WHO ICTRP), and reference lists of all papers and relevant reviews. Randomized controlled trials comparing people with diabetes randomized to lower or to standard BP targets as previously defined, and providing data on any of the primary outcomes below. Two review authors independently assessed and established the included trials and data entry. Primary outcomes were total mortality; total serious adverse 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. We found five randomized trials, recruiting a total of 7314 participants and with a mean follow-up of 4.5 years. Only one trial (ACCORD) compared outcomes associated with 'lower' (< 120 mmHg) or 'standard' (< 140 mmHg) systolic blood pressure targets in 4734 participants. Despite achieving a significantly lower BP (119.3/64.4 mmHg vs 133.5/70.5 mmHg, P < 0.0001), and using more antihypertensive medications, the only significant benefit in the group assigned to 'lower' systolic blood pressure (SBP) was a reduction in the incidence of stroke: risk ratio (RR) 0.58, 95% confidence interval (CI) 0.39 to 0.88, P = 0.009, absolute risk reduction 1.1%. The effect of SBP targets on mortality was compatible with both a reduction and increase in risk: RR 1.05 CI 0.84 to 1.30, low quality evidence. Trying to achieve the 'lower' SBP target was associated with a significant increase in the number of other serious adverse events: RR 2.58, 95% CI 1.70 to 3.91, P < 0.00001, absolute risk increase 2.0%.Four trials (ABCD-H, ABCD-N, ABCD-2V, and a subgroup of HOT) specifically compared clinical outcomes associated with 'lower' versus 'standard' targets for diastolic blood pressure (DBP) in people with diabetes. The total number of participants included in the DBP target analysis was 2580. Participants assigned to 'lower' DBP had a significantly lower achieved BP: 128/76 mmHg vs 135/83 mmHg, P < 0.0001. There was a trend towards reduction in total mortality in the group assigned to the 'lower' DBP target (RR 0.73, 95% CI 0.53 to 1.01), mainly due to a trend to lower non-cardiovascular mortality. There was no difference in stroke (RR 0.67, 95% CI 0.42 to 1.05), in myocardial infarction (RR 0.95, 95% CI 0.64 to 1.40) or in congestive heart failure (RR 1.06, 95% CI 0.58 to 1.92), low quality evidence. End-stage renal failure and total serious adverse events were not reported in any of the trials. A sensitivity analysis of trials comparing DBP targets < 80 mmHg (as suggested in clinical guidelines) versus < 90 mmHg showed similar results. There was a high risk of selection bias for every outcome analyzed in favor of the 'lower' target in the trials included for the analysis of DBP targets. At the present time, evidence from randomized trials does not support blood pressure targets lower than the standard targets in people with elevated blood pressure and diabetes. More randomized controlled trials are needed, with future trials reporting total mortality, total serious adverse events as well as cardiovascular and renal events. Source

Araya M.,University of Costa Rica
Monthly Notices of the Royal Astronomical Society | Year: 2013

52 months of accumulated observations by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope in the region of the supernova remnants G296.5+10.0 (PKS 1209-51/52) and G166.0+4.3 (VRO 42.05.01) are analysed. GeV emission is detected coincident with the position of the sources at the {minus tilde}5σ and 11σ levels above the background, respectively, for the best-fitting spectral and spatial scenarios. The gamma-ray spectrum of the sources can be described with a power law in energy. G166.0+4.3 shows a soft GeV spectrum while that of G296.5+10.0 is flat (in the νFν representation). The origin of the gamma-ray emission from the sources is explored. Both leptonic and hadronic mechanisms can account for the high-energy emission from G296.5+10.0, while a leptonic scenario is preferred for G166.0+4.3. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

The larva of the ichneumonid wasp Polysphincta gutfreundi induces its host, the orb-weaving spider Allocyclosa bifurca, to build a highly modified, physically stable orb web, to which the larva then attaches its pupal cocoon, and to add an otherwise unusual linear silk stabilimentum to this web that may camouflage the cocoon. The effects of the larva are apparently due to a chemical product or products that it introduces into the spider. Behavioural modification is gradual, and various behavioural effects arise in a consistent order. If the wasp larva is experimentally removed just before it kills the spider, the spider's behaviour recovers gradually in the reverse order. In addition, a greater delay in removing the larva leads to more pronounced and enduring behavioural changes, so the larval effects may depend on a cumulative or dose-dependent process. Changes in numbers and lengths of radii and numbers of sticky spiral loops could result from correlated larval effects on the reduction in the amount of silk in the spider's sticky spiral silk glands (or a signal thereof), but several other types of behavioural change are probably under separate controls; multiple larval products may be involved. The larvae may affect higher levels of behavioural decisions by spiders that determine overall web 'design', rather than lower levels, such as control of particular behaviour patterns, as may be affected by related wasps. The larva's effects are fine-tuned to details of the host's natural history. Source

Eberhard W.G.,University of Costa Rica
Animal Behaviour | Year: 2011

Because of scaling trends in physiology and morphology, very small animals are expected to suffer especially strong selection to reduce the cost of the central nervous system, which may make them more likely to sacrifice behavioural capacities to economize on nervous tissue. This 'size-limitation' hypothesis predicts reduced behavioural capabilities in smaller animals. I tested this hypothesis by comparing web construction behaviour of young nymphs and adults of a very small orb-weaving spider, Anapisona simoni (young nymphs ∼0.005mg, adults ∼0.8mg), with those of relatives up to 10 4 times larger. In these comparisons I took advantage of the special opportunities offered by orb webs to study fine behavioural details during web construction, because the webs represent precise records of large numbers of behavioural decisions. Combining these results with those of a previous study, the size-limitation hypothesis was not supported: very small spiders failed to show three predicted trends, and they showed four other trends that were in directions opposite to those predicted by the hypothesis. Two additional intraweb comparisons (at least one of which was probably biased against equal performance by the smallest species) gave a mix of support and lack of support for the predictions, while only one interspecific difference supported the predictions. Other studies have shown that small spiders have relatively large central nervous systems for their body sizes, suggesting that they may maintain behavioural capabilities comparable to those of larger orb weavers by paying the material and metabolic costs of building and maintaining large volumes of nervous tissue. These considerations may have general consequences for the probability of evolving small body sizes and egg sizes in spiders and other animals. © 2011. Source

Discover hidden collaborations