Effects of experimental tail shortening on the phenotypic condition of barn swallows Hirundo rustica: Implications for tail-length evolution

Some studies have suggested that tail streamers in the barn swallow Hirundo rustica may have been elongated 10-12 mm by sexual selection, but according to other studies, the length of these feathers is at the aerodynamic optimum or very close to it. To shed light on this issue, outermost tail feathers were experimentally shortened in male and female barn swallows by 1, 11 or 21 mm. Changes in four physiological parameters commonly used to estimate phenotypic condition in birds (weight, erythrocyte sedimentation rate, blood leukocyte concentration and heterophil/lymphocyte ratio) were checked one month later. Health improved (blood leukocyte concentration decreased) in the group of birds with tails shortened by 11 mm (both males and females), but body condition deteriorated (weight decreased) compared to the other two experimental groups. There was no significant effect of tail-length manipulation on the other two physiological parameters. These contradictory results suggest trade-offs between components of phenotypic condition. Possible negative relationships between condition-related traits imply that using one or very few physiological parameters to estimate phenotypic condition might not be appropriate. The most plausible explanation for the turning point in phenotypic condition when streamers were shortened by 11 mm is that these feathers are 7-15 mm longer than the aerodynamic optimum in both sexes. Therefore, our results are consistent with the hypothesis that tail streamers have been elongated 10-12 mm by sexual selection. This conclusion disagrees with a previous study on the effect of experimental tail shortening on haematocrit, but the complexity of interpreting changes in haematocrit might account for this discrepancy. © 2014 The Authors.The study was funded by the Andalusian Regional Government (Acc. Coord. 2001) and by the Spanish Ministry of Science and Technology and the European Regional Development Fund (projects BOS2001-1717 and CGL2008-00137/BOS).Peer Reviewe

Decreasing Sleep-Time Blood Pressure Determined by Ambulatory Monitoring Reduces Cardiovascular Risk

ObjectivesWe investigated whether reduced cardiovascular risk is more related to the progressive decrease of asleep or awake blood pressure.BackgroundIndependent studies have concluded that elevated sleep-time blood pressure is a better predictor of cardiovascular risk than awake or 24-h blood pressure means. However, the impact on cardiovascular risk of changes in these ambulatory blood pressure characteristics has not been properly investigated.MethodsWe prospectively studied 3,344 subjects (1,718 men and 1,626 women), 52.6 ± 14.5 years of age, during a median follow-up of 5.6 years. Those with hypertension at baseline were randomized to ingest all their prescribed hypertension medications upon awakening or ≥1 of them at bedtime. Blood pressure was measured for 48 h at baseline and again annually or more frequently (quarterly) if treatment adjustment was required.ResultsWith data collected at baseline, when asleep blood pressure was adjusted by awake mean, only the former was a significant predictor of outcome in a Cox proportional hazards model also adjusted for sex, age, and diabetes. Analyses of changes in ambulatory blood pressure during follow-up revealed a 17% reduction in cardiovascular risk for each 5-mm Hg decrease in asleep systolic blood pressure mean (p < 0.001), independently of changes in any other ambulatory blood pressure parameter.ConclusionsThe sleep-time blood pressure mean is the most significant prognostic marker of cardiovascular morbidity and mortality. Most importantly, the progressive decrease in asleep blood pressure, a novel therapeutic target that requires proper patient evaluation by ambulatory monitoring, was the most significant predictor of event-free survival. (Prognostic Value of Ambulatory Blood Pressure Monitoring in the Prediction of Cardiovascular Events and Effects of Chronotherapy in Relation to Risk [the MAPEC Study]; NCT00295542

Study of the stabilization energies of halide-water clusters: An application of first-principles interaction potentials based on a polarizable and flexible model

The aim of this work is to compute the stabilization energy Estab(n) of [ X(H2O)n ]- (X=F, Br, and I for n=1 – 60) clusters from Monte Carlo simulations using first-principles ab initio potentials. Stabilization energy of [ X(H2O)n ]- clusters is defined as the difference between the vertical photodeachment energy of the cluster and the electron affinity of the isolated halide. On one hand, a study about the relation between cluster structure and the Estab(n) value, as well as the dependence of the latter with temperature is performed, on the other hand, a test on the reliability of our recently developed first-principles halide ion-water interaction potentials is carried out. Two different approximations were applied: (1) the Koopmans’ theorem and (2) calculation of the difference between the interaction energy of [ X(H2O)n ]- and [ X(H2O)n ] clusters using the same ab initio interaction potentials. The developed methodology allows for using the same interaction potentials in the case of the ionic and neutral clusters with the proviso that the charge of the halide anion was switched off in the latter. That is, no specific parametrization of the interaction potentials to fit the magnitude under study was done. The good agreement between our predicted Estab(n) and experimental data allows us to validate the first-principles interaction potentials developed elsewhere and used in this study, and supports the fact that this magnitude is mainly determined by electrostatic factors, which can be described by our interaction potentials. No relation between the value of Estab(n) and the structure of clusters has been found. The diversity of Estab(n) values found for different clusters with similar interaction energy indicates the need for statistical information to properly estimate the stabilization energy of the halide anions. The effect of temperature in the prediction of the Estab(n) is not significant as long as it was high enough to avoid cluster trapping into local equilibrium configurations which guarantees an appropriate sampling of the configurational space. Parallel tempering method was applied in particular cases to guarantee satisfactory sampling of clusters at low temperatureDirección General de Investigaciones Científicas y Técnicas BQU2002- 0221

Micro- and nanoparticle generation during nanosecond laser ablation: correlation between mass and optical emissions

The particulate emission during nanosecond ablation of gold targets was investigated at various fluences (10-100 Jcm(-2)) and vacuum levels (0.05-750 Torr). Atomic emission spectra were acquired during the ablation process and post-mortem characterization of particle spatial distribution was performed using scanning electron microscopy. The discussion of the results in the context of existing theoretical models permitted the identification of four distinct mass removal mechanisms. While the presence, shape and intensity of atomic emission lines is a telltale of the nanoparticle formation process, the fluctuations of the emission signal over a number of laser shots was linked to the production of microscopic debris

On the halide hydration study: Development of first-principles halide ion-water interaction potential based on a polarizable model

The development of first-principles halide-water interaction potentials for fluoride and iodide anions is presented. The model adopted is the mobile charge densities in harmonic oscillator that allows for a flexible and polarizable character of the interacting particles. The set of points of the quantum mechanical potential energy surfaces are calculated up to the MP2 level. The nonadditive many-body contributions were included explicitly at the three-body terms. Structural and energetic properties of the [ X(H2O)n ]- clusters (n=1 – 6) are studied with the new interaction potentials developed. Halide aqueous solutions are also studied by means of Monte Carlo simulations. The agreement between experimental and our predicted estimations shows the good behavior of the proposed potentials. The developed potentials are able to properly describe both the microsolvation of clusters in gas phase and their hydration in aqueous solutions. The different nature of the interactions among F-, Br-, I- and water appears in the set of studied properties, thus giving a gradual change in the behavior along the group.Dirección General de Investigaciones Científicas y Técnicas BQU2002-0221

Wheat Straw Open Burning: Emissions and Impact on Climate Change

The state of Baja California, Mexico, is the second national wheat producer. Mexicali, the capital of Baja California, is the primary wheat producer, and it represents the most significant crop in the valley, with 90,609 ha of a cultivated surface by 2015; it leads to a wheat production of 585,334 t and a generation of 661,446 t of wheat straw as agricultural residue. The 15% of this waste has various uses. The 85% of wheat straw is open burnt in situ to prepare the farmland for the next agricultural cycle. Through the development of an emissions and energy model on iThink®, the emissions of 6,185 t of PM, 35,983 t of CO, and 1,125 t of CH4 considering a headfire burning or 3,373 t of PM, 30,360 t of CO, and 731 t of CH4 by backfire burning were estimated. Also, the wheat straw wasted energy was estimated at 8.15 PJ by 2015, with a lower heating value of 14.50 MJ/kg determined experimentally. The results highlight that for each hectare of harvested wheat, 6.205 t of wheat straw are generated and burnt. It represents the emission of pollutants and 89,972.50 MJ of wasted energy

Interplay of computer simulations and x-ray absorption spectra in the study of the bromide hydration structure

X-ray absorption spectra (EXAFS and XANES) were generated from snapshots of a Monte Carlo (MC) simulation of a bromide ion aqueous solution and from model structures. The MC simulation relies on a recently developed and tested polarizable potential based on ab initio potential energy surfaces. A comparison with the experimental K-edge Br spectrum of a 0.3 M YBr3 aqueous solution was performed. XANES spectra are reproduced acceptably only if statistical fluctuations are included, which is performed in this work by using snapshots from computer simulation. As expected, single scattering BrO contributions are dominant in the case of the EXAFS region. Due to this fact, Br- in water is a good model system for studying the influence of the distribution of distances on the determination of structural parameters. Then, a parallel study of the data analysis procedure of the experimental EXAFS spectrum and those theoretically computed from the structures supplied by the MC simulation, was carried out. The shape of the distribution function and its asymmetry must be taken into account in a practical way to obtain a more accurate determination of the BrO first-shell distance. A further refinement consists in using the computer simulation to extrapolate the BrO distance from the experimental EXAFS spectrum. In this way, a BrO distance of 3.44±0.07 Å and a coordination number of 6±0.5 were determine

Development of first-principles interaction model potentials. An application to the study of the bromide hydration

This work presents the development of first-principles bromide ion–water interaction potentials using the mobile charge density in harmonic oscillators-type model. This model allows for a flexible and polarizable character of the interacting molecules and has already been parametrized for water– water interactions. The prospected potential energy surfaces of the bromide ion-water system were computed quantum-mechanically at Hartree–Fock and Møller–Plesset second-order perturbation levels. In addition to the ion–solvent molecule pair, structures formed by the anion and two or three water molecules were considered in order to include many body effects. Minimizations of hydrated bromide clusters in gas phase [ Br(H2O)n ]- (n=1 – 6,10,15,20) and Monte Carlo computations of bromide aqueous solutions were performed to test the new potentials. Both structural and thermodynamic properties have been studied in detail and compared to the available experimental and theoretical values. From these comparisons, it was concluded the importance of including basis set superposition error corrections for the two-body interactions, and the small role of both electron correlation on the three-body terms and the four-body terms. Monte Carlo simulation results have also been used to investigate if the presence of the anion significantly affects the intramolecular geometry of the water molecules and the degree of disruption of the water solvent structure in its vicinityDirección General de Investigaciones Científicas y Técnicas PB98-1153Junta de Andalucía FQM 282DGAPA-UNAM IN110399CONACYT G33362-