University of Los Andes

About: University of Los Andes is a education organization based out in Bogotá, Colombia. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 17616 authors who have published 25555 publications receiving 413463 citations.

Regulation of water flux through trunks, branches, and leaves in trees of a lowland tropical forest

Abstract: We studied regulation of whole-tree water use in individuals of five diverse canopy tree species growing in a Panamanian seasonal forest. A construction crane equipped with a gondola was used to access the upper crowns and points along the branches and trunks of the study trees for making concurrent measurements of sap flow at the whole-tree and branch levels, and vapor phase conductances and water status at the leaf level. These measurements were integrated to assess physiological regulation of water use from the whole-tree to the single-leaf scale. Whole-tree water use ranged from 379 kg day-1 in a 35 m-tall Anacardium excelsum tree to 46 kg day-1 in an 18 m-tall Cecropia longipes tree. The dependence of whole-tree and branch sap velocity and sap flow on sapwood area was essentially identical in the five trees studied. However, large differences in transpiration per unit leaf area (E) among individuals and among branches on the same individual were observed. These differences were substantially reduced when E was normalized by the corresponding branch leaf area:sapwood area ratio (LA/SA). Variation in stomatal conductance (g s) and crown conductance (g c), a total vapor phase conductance that includes stomatal and boundary layer components, was closely associated with variation in the leaf area-specific total hydraulic conductance of the soil/leaf pathway (G t). Vapor phase conductance in all five trees responded similarly to variation in G t. Large diurnal variations in G t were associated with diurnal variation in exchange of water between the transpiration stream and internal stem storage compartments. Differences in stomatal regulation of transpiration on a leaf area basis appeared to be governed largely by tree size and hydraulic architectural features rather than physiological differences in the responsiveness of stomata. We suggest that reliance on measurements gathered at a single scale or inadequate range of scale may result in misleading conclusions concerning physiological differences in regulation of transpiration.

Aldosterone Promotes Autoimmune Damage by Enhancing Th17-Mediated Immunity

Abstract: Excessive production of aldosterone leads to the development of hypertension and cardiovascular disease by generating an inflammatory state that can be promoted by T cell immunity. Because nature and intensity of T cell responses is controlled by dendritic cells (DCs), it is important to evaluate whether the function of these cells can be modulated by aldosterone. In this study we show that aldosterone augmented the activation of CD8(+) T cells in a DC-dependent fashion. Consistently, the mineralocorticoid receptor was expressed by DCs, which showed activation of MAPK pathway and secreted IL-6 and TGF-beta in response to aldosterone. In addition, DCs stimulated with aldosterone impose a Th17 phenotype to CD4(+) T cells, which have recently been associated with the promotion of inflammatory and autoimmune diseases. Accordingly, we observed that aldosterone enhances the progression of experimental autoimmune encephalomyelitis, an autoimmune disease promoted by Th17 cells. In addition, blockade of the mineralocorticoid receptor prevented all aldosterone effects on DCs and attenuated experimental autoimmune encephalomyelitis development in aldosterone-treated mice. Our data suggest that modulation of DC function by aldosterone enhances CD8(+) T cell activation and promotes Th17-polarized immune responses, which might contribute to the inflammatory damage leading to hypertension and cardiovascular disease.

A twenty-first century assessment of values across the global workforce

Abstract: This article provides current Schwartz Values Survey (SVS) data from samples of business managers and professionals across 50 societies that are culturally and socioeconomically diverse. We report the society scores for SVS values dimensions for both individual- and societal-level analyses. At the individual-level, we report on the ten circumplex values sub-dimensions and two sets of values dimensions (collectivism and individualism; openness to change, conservation, self-enhancement, and self-transcendence). At the societal-level, we report on the values dimensions of embeddedness, hierarchy, mastery, affective autonomy, intellectual autonomy, egalitarianism, and harmony. For each society, we report the Cronbach’s α statistics for each values dimension scale to assess their internal consistency (reliability) as well as report interrater agreement (IRA) analyses to assess the acceptability of using aggregated individual level values scores to represent country values. We also examined whether societal development level is related to systematic variation in the measurement and importance of values. Thus, the contributions of our evaluation of the SVS values dimensions are two-fold. First, we identify the SVS dimensions that have cross-culturally internally reliable structures and within-society agreement for business professionals. Second, we report the society cultural values scores developed from the twenty-first century data that can be used as macro-level predictors in multilevel and single-level international business research.

Evidence for a B-s(0)pi(+/-) State

Abstract: We report evidence for a narrow structure, X(5568), in the decay sequence X(5568) -> B-s(0)pi(+/-), B-s(0) -> J/psi phi, J/psi -> mu(+)mu(-), phi -> K+K-. This is evidence for the first instance of a hadronic state with valence quarks of four different flavors. The mass and natural width of this state are measured to be m = 5567.8 +/- 2.9(stat)(-1.9)(+0.9) (syst) MeV/c(2) and Gamma = 21.9 +/- 6.4(stat)(-2.5)(+5.0) (syst) MeV/c(2). If the decay is X(5568) -> B-s*pi(+/-). B-s(0)gamma pi(+/-) with an unseen gamma, m(X(5568)) will be shifted up by m(B-s*) - m(B-s(0)) similar to 49 MeV/c(2). This measurement is based on 10.4 fb(-1) of p (p) over bar collision data at root s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron collider.