Inferring landscape effects on dispersal from genetic distances: how far can we go?

Functional connectivity affects demography and gene dynamics in fragmented populations. Besides species-specific dispersal ability, the connectivity between local populations is affected by the landscape elements encountered during dispersal. Documenting these effects is thus a central issue for the conservation and management of fragmented populations. In this study, we compare the power and accuracy of three methods (partial correlations, regressions and Approximate Bayesian Computations) that use genetic distances to infer the effect of landscape upon dispersal. We use stochastic individual-based simulations of fragmented populations surrounded by landscape elements that differ in their permeability to dispersal. The power and accuracy of all three methods are good when there is a strong contrast between the permeability of different landscape elements. The power and accuracy can be further improved by restricting analyses to adjacent pairs of populations. Landscape elements that strongly impede dispersal are the easiest to identify. However, power and accuracy decrease drastically when landscape complexity increases and the contrast between the permeability of landscape elements decreases. We provide guidelines for future studies and underline the needs to evaluate or develop approaches that are more powerful.

Low molecular weight carboxylic acids in oxidizing porphyry copper tailings

The distribution of low molecular weight carboxylic acids (LMWCA) was investigated in pore water profiles from two porphyry copper tailings impoundments in Chile (Piuquenes at La Andina and Cauquenes at El Teniente mine). The objectives of this study were (1) to determine the distribution of LMWCA, which are interpreted to be the metabolic byproducts of the autotroph microbial community in this low organic carbon system, and (2) to infer the potential role of these acids in cycling of Fe and other elements in the tailings impoundments. The speciation and mobility of iron, and potential for the release of H+ via hydrolysis of the ferric iron, are key factors in the formation of acid mine drainage in sulfidic mine wastes. In the low-pH oxidation zone of the Piuquenes tailings, Fe(III) is the dominant iron species and shows high mobility. LMWCA, which occur mainly between the oxidation front down to 300 cm below the tailings surface at both locations (e.g., max concentrations of 0.12 mmol/L formate, 0.17 mmol/L acetate, and 0.01 mmol/L pyruvate at Piuquenes and 0.14 mmol/L formate, 0.14 mmol/L acetate, and 0.006 mmol/L pyruvate at Cauquenes), are observed at the same location as high Fe concentrations (up to 71.2 mmol/L Fe(II) and 16.1 mmol/L Fe(III), respectively). In this zone, secondary Fe(111) hydroxides are depleted. Our data suggest that LMWCA may influence the mobility of iron in two ways. First, complexation of Fe(III), through formation of bidentate Fe(III)-LMWCA complexes (e.g., pyruvate, oxalate), may enhance the dissolution of Fe(III) (oxy)hydroxides or may prevent precipitation of Fe(III) (oxy)hydroxides. Soluble Fe(III) chelate complexes which may be mobilized downward and convert to Fe(II) by Fe(III) reducing bacteria. Second, monodentate LMWCA (e.g., acetate and formate) can be used by iron-reducing bacteria as electron donors (e.g., Acidophilum spp.), with ferric iron as the electron acceptor. These processes may, in part, explain the low abundances of secondary Fe(III) hydroxide precipitates below the oxidation front and the high concentrations of Fe(II) observed in the pore waters of some low-sulfide systems. The reduction of Fe(III) and the subsequent increase of iron mobility and potential acidity transfer (Fe(II) oxidation can result in the release of H+ in an oxic environment) should be taken in account in mine waste management strategies.

MHC class I-related chain A conjugated to antitumor antibodies can sensitize tumor cells to specific lysis by natural killer cells.

PURPOSE: As a first step for the development of a new cancer immunotherapy strategy, we evaluated whether antibody-mediated coating by MHC class I-related chain A (MICA) could sensitize tumor cells to lysis by natural killer (NK) cells. EXPERIMENTAL DESIGN: Recombinant MICA (rMICA) was chemically conjugated to Fab' fragments from monoclonal antibodies specific for tumor-associated antigens, such as carcinoembryonic antigen, HER2, or CD20. RESULTS: Flow cytometry analysis showed an efficient coating of MICA-negative human cancer cell lines with the Fab-rMICA conjugates. This was strictly dependent on the expression of the appropriate tumor-associated antigens in the target cells. Importantly, preincubation of the tumor cells with the appropriate Fab-rMICA conjugate resulted in NK cell-mediated tumor cell lysis. Antibody blocking of the NKG2D receptor in NK cells prevented conjugate-mediated tumor cell lysis. CONCLUSIONS: These results open the way to the development of immunotherapy strategies based on antibody-mediated targeting of MICA.

Can postictal memory predict postoperative memory in patients with temporal lobe epilepsy?

We investigated the contribution of postictal memory testing for lateralizing the epileptic focus and predicting memory outcome after surgery for temporal lobe epilepsy (TLE). Forty-five patients with TLE underwent interictal, postictal, and postoperative assessment of verbal and nonverbal memory. Surgery consisted of anterior temporal lobectomy (36), selective isolated amygdalohippocampectomy (6), or amygdalohippocampectomy coupled to lesionectomy (3). Postictal and postoperative but not interictal memory were significantly lower in left TLE than in right TLE. Nonverbal memory showed no significant difference in left TLE versus right TLE in all conditions. Postictal memory was significantly correlated with postoperative memory, but the effect disappeared when the lateralization of the focus was considered. Postictal verbal memory is a useful bedside tool that can help lateralize the epileptic focus. Larger studies are needed to further estimate its predictive value of the postoperative outcome.

Can we identify Walrasian allocations?

[eng] We consider a discrete time, pure exchange infinite horizon economy with two or more consumers and at least one concumption good per period. Within the framework of decentralized mechanisms, we show that for a given consumption trade at any period of time, say at time one, the consumers will need, in general, an infinite dimensional (informational) space to identigy such a trade as an intemporal Walrasian one. However, we show and characterize a set of enviroments where the Walrasian trades at each period of time can be achieved as the equilibrium trades of a sequence of decentralized competitive mechanisms, using only both current prices and quantities to coordinate decisions.

"¿Es necesario un Código Ético de la Comunidad Universitaria?"

Voy a plantear una serie de preguntas sencillas y claras, e intentaré proporcionar las respuestas que considero que pueden sernos útiles en este momento. No voy a navegar por lugares muy altos de la ética, ni de la filosofía, porque en este caso entiendo que mi aportación consiste en proporcionar una posible manera de abordar un conflicto, es decir una pauta.Voy a tratar de analizar las cuestiones que seplantean y cómo podemos enfocarlas.

Fruits et légumes: peuvent-ils être dangereux? [Fruits and vegetables: can they be dangerous?].

Fruits, vegetables and spices are found in our everyday food consumption. However, some contain potentially toxic substances, particularly when consumed in large amounts. These risks may be greater for certain susceptible individuals and may depend on how the ingredients are prepared. Food poisoning is generally speaking self-limiting, but may be life threatening. This article discusses the possible toxic effects of certain common foodstuffs, as described in the current medical literature.

Can Valproic Acid be an Inducer of Clozapine Metabolism?

Introduction: Prior clozapine studies indicated no effects, mild inhibition or induction of valproic acid (VPA) on clozapine metabolism. The hypotheses that (i) VPA is a net inducer of clozapine metabolism, and (ii) smoking modifies this inductive effect were tested in a therapeutic drug monitoring study. Methods: After excluding strong inhibitors and inducers, 353 steady-state total clozapine (clozapine plus norclozapine) concentrations provided by 151 patients were analyzed using a random intercept linear model. Results: VPA appeared to be an inducer of clozapine metabolism since total plasma clozapine concentrations in subjects taking VPA were significantly lower (27% lower; 95% confidence interval, 14-39%) after controlling for confounding variables including smoking (35% lower, 28-56%). Discussion: Prospective studies are needed to definitively establish that VPA may (i) be an inducer of clozapine metabolism when induction prevails over competitive inhibition, and (ii) be an inducer even in smokers who are under the influence of smoking inductive effects on clozapine metabolism.

Breus notes sobre els escarabeus i escaraboides de la necròpolis de Can Canyís

Al Congreso Nacional de Arqueología de Barcelona, Vilaseca, Solé i Mañé van donar la notícia del descobriment de la necrópolis de Can Canyís, l'agost de 1960, la qual havia estat completament destruida feia poc pels treballs agrícoles.! Per aquest motiu, els objectes trobats no estaven relacionats en concret amb els fragments d'urnes i no es va poder reconstruir l'aixovar complet de cap enterrament. La cronologia atribUIda al conjunt de la necrópolis pels seus excavadors va del 600 al 450. La memoria deIs treballs va ser publicada uns anys més tard pels mateixos autors incorporant l'excavació d'una tomba intacta de guerrer.

Pédiatrie. 1. Comment favoriser le développement de l'oralité en néonatologie [Pediatrics. How can we improve oral feeding in the neonatal intensive care unit?].

Preterm or sick neonates are frequently hampered in establishing a safe and efficient oral feeding. This can delay hospital discharge and impact on parent-child bonding, growth or neurodevelopment. Recent researches identified a pattern of interventions that could allow to reduce these troubles and to shorten hospital stays.

Can we disentangle predator-prey interactions from species distributions at a macro-scale? A case study with a raptor species.

There is a debate on whether an influence of biotic interactions on species distributions can be reflected at macro-scale levels. Whereas the influence of biotic interactions on spatial arrangements is beginning to be studied at local scales, similar studies at macro-scale levels are scarce. There is no example disentangling, from other similarities with related species, the influence of predator-prey interactions on species distributions at macro-scale levels. In this study we aimed to disentangle predator-prey interactions from species distribution data following an experimental approach including a factorial design. As a case of study we selected the short-toed eagle because of its known specialization on certain prey reptiles. We used presence-absence data at a 100 Km2 spatial resolution to extract the explanatory capacity of different environmental predictors (five abiotic and two biotic predictors) on the short-toed eagle species distribution in Peninsular Spain. Abiotic predictors were relevant climatic and topographic variables, and relevant biotic predictors were prey richness and forest density. In addition to the short-toed eagle, we also obtained the predictor's explanatory capacities for i) species of the same family Accipitridae (as a reference), ii) for other birds of different families (as controls) and iii) species with randomly selected presences (as null models). We run 650 models to test for similarities of the short-toed eagle, controls and null models with reference species, assessed by regressions of explanatory capacities. We found higher similarities between the short-toed eagle and other species of the family Accipitridae than for the other two groups. Once corrected by the family effect, our analyses revealed a signal of predator-prey interaction embedded in species distribution data. This result was corroborated with additional analyses testing for differences in the concordance between the distributions of different bird categories and the distributions of either prey or non-prey species of the short-toed eagle. Our analyses were useful to disentangle a signal of predator-prey interactions from species distribution data at a macro-scale. This study highlights the importance of disentangling specific features from the variation shared with a given taxonomic level.