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.

Seasonal prediction of extreme precipitation events and frequency of rainy days over Costa Rica, Central America, using Canonical Correlation Analysis

Abstract: . High mountains divide Costa Rica, Central America, into two main climate regions, the Pacific and Caribbean slopes, which are lee and windward, respectively, according to the North Atlantic trade winds – the dominant wind regime. The rain over the Pacific slope has a bimodal annual cycle, having two maxima, one in May–June and the other in August-September-October (ASO), separated by the mid-summer drought in July. A first maximum of deep convection activity, and hence a first maximum of precipitation, is reached when sea surface temperature (SST) exceeds 29 °C (around May). Then, the SST decreases to around 1 °C due to diminished downwelling solar radiation and stronger easterly winds (during July and August), resulting in a decrease in deep convection activity. Such a reduction in deep convection activity allows an increase in down welling solar radiation and a slight increase in SST (about 28.5 °C) by the end of August and early September, resulting once again in an enhanced deep convection activity, and, consequently, in a second maximum of precipitation. Most of the extreme events are found during ASO. Central American National Meteorological and Hydrological Services (NMHS) have periodic Regional Climate Outlook Fora (RCOF) to elaborate seasonal predictions. Recently, meetings after RCOF with different socioeconomic stakeholders took place to translate the probable climate impacts from predictions. From the feedback processes of these meetings has emerged that extreme event and rainy days seasonal predictions are necessary for different sectors. As is shown in this work, these predictions can be tailored using Canonical Correlation Analysis for rain during ASO, showing that extreme events and rainy days in Central America are influenced by interannual variability related to El Nino-Southern Oscillation and decadal variability associated mainly with Atlantic Multidecadal Oscillation. Analyzing the geographical distribution of the ASO-2010 disaster reports, we noticed that they did not necessarily agree with the geographical extreme precipitation event distribution, meaning that social variables, like population vulnerability, should be included in the extreme events impact analysis.

Diabetes-related lower-extremity amputation incidence and risk factors: a prospective seven-year study in Costa Rica

Abstract: OBJECTIVE: To analyze the incidence and determinants of lower-extremity amputation (LEA) in people with diabetes in a low-income community in Costa Rica. METHODS: Data on LEA incidence were collected during a seven-year follow-up (2001-2007) in a diabetes patient cohort (n = 572). Risk factors were analyzed using the Cox proportional hazards regression model and baseline variables from the year 2000 (socio- demographic characteristics, comorbidity, metabolic control, treatment, and chronic microvascular complications). RESULTS: LEA incidence was 6.02 per 1 000 person-years (8.65 in men and 4.50 in women). Known risk factors (sex, years of diabetes, elevated glycated hemoglobin [HbA1c], retinopathy, insulin therapy, and prior amputation) were highly significant. CONCLUSIONS: Those most likely to undergo LEA among Costa Rican diabetic patients were men with 10 or more years of diabetes and average HbA1c > 8% who used insulin and had diabetic retinopathy. Patients on insulin therapy were at greatest risk, especially those with a previous amputation. Diabetic patients with the above-mentioned profile should be considered to be at very high risk of LEA and followed closely by the health care system.

Incorporation of basic side chains into cryptolepine scaffold: structure-antimalarial activity relationships and mechanistic studies.

Abstract: The synthesis of cryptolepine derivatives containing basic side-chains at the C-11 position and their evaluations for antiplasmodial and cytotoxicity properties are reported. Propyl, butyl, and cycloalkyl diamine side chains significantly increased activity against chloroquine-resistant Plasmodium falciparum strains while reducing cytotoxicity when compared with the parent compound. Localization studies inside parasite blood stages by fluorescence microscopy showed that these derivatives accumulate inside the nucleus, indicating that the incorporation of a basic side chain is not sufficient enough to promote selective accumulation in the acidic digestive vacuole of the parasite. Most of the compounds within this series showed the ability to bind to a double-stranded DNA duplex as well to monomeric hematin, suggesting that these are possible targets associated with the observed antimalarial activity. Overall, these novel cryptolepine analogues with substantially improved antiplasmodial activity and selectivity index provide a promising starting point for development of potent and highly selective agents against drug-resistant malaria parasites.

Connecting Pairs of Dimetal Units To Form Molecular Loops

Abstract: Four compounds consisting of molecular loops formed from two quadruply bonded Mo2(DAniF)2 (DAniF = N,N'-di-p-anisylformamidinate) units linked by two dicarboxylate anions have been prepared in high purity and essentially quantitative yields. These compounds have been characterized by crystallography and NMR spectroscopy and display electrochemical behavior dependent on the nature of the dicarboxylate anion. However, the electronic communication between the two Mo2(4+) units is not strong. As denoted by the dicarboxylate linkers, the compounds are malonate, 1, 1,4-phenylendiacetate, 2, homophthalate, 3, and trans-cyclopentane-1,2-dicarboxylate, 4.

Decisions during courtship by male and female medflies (diptera, tephritidae): correlated changes in male behavior and female acceptance criteria in mass-reared flies

Abstract: Analyses of more than 300 videotaped courtships of wild and mass-reared medflies from Costa Rica showed that the tendency for male and female to align themselves facing directly toward each other increased, and that the distance between them decreased as courtship proceeded. More direct alignments and shorter distances between the flies at the moment the male jumped onto the female were correlated with greater female acceptance of copulation. There were no consistent differences in durations of components of intermittent buzzing songs or male size between successful and unsuccessful courtship in either strain. Several possible cues may release different courtship responses: males of both strains tend to initiate both continuous vibration and intermittent buzzing after reduction of the distance to the female; slow creeping toward the female was associated with longer courtships that had failed to lure the female close; and females tended to turn to face more directly toward the male soon after the male began continuous vibration, and especially after he began intermittent buzzing. Females became progressively more immobile as courtship progressed, especially soon after intermittent buzzing began. There were numerous differences between strains. Mass-reared males were more likely to mount females without previous courtship than were wild males. Wild males initiated continuous wing vibration when farther from the female and when the female was looking less directly toward them, but the two strains did not differ in the distances and angles at which males initiated intermittent buzzing and jumped. Wild males were more likely to creep toward the female during intermittent buzzing. Mass-reared females but not wild females were more likely to copulate when the proportion of time the male had spent in intermittent buzzing was low, and if the courtship began when the flies were nearer each other. Wild but not mass-reared females were less likely to copulate if courtship was shorter. Possible coevolution of female responses with the five different male courtship traits that differ between mass-reared and wild flies are discussed.