Long-term effects of social stress exposure during adolescence in impulsivity : toward a new model of aggression

Adolescent male hamsters exposed to chronic social stress become themselves aggressive adults, evidenced by increased frequency of attacks and shorter latencies to attack opponents. Perhaps, this enhanced aggression is associated with a lack of impulse control, in particular with the ability to inhibit responses (i.e. action inhibition) and wait to respond (i.e. waiting impulsivity). Male golden hamsters were exposed daily to aggressive adults from postnatal day 28 to 42. Later, the animals were trained in conditioning chambers and tested in a Go-NoGo task to evaluate action inhibition. Overall, previously stressed hamsters were less likely to inhibit a conditioned lever pressing response during NoGo trials. These results show that animals exposed to social stress in early adolescence, have a decrease ability to withhold responses, which could possible explain why as adults, they have higher frequency of attacks. To test waiting impulsivity, animals learned to respond to a main house-light by nose-poking in any of two, adjacent illuminated ports in a modified version of a 5-choice-serial-reaction-time task (5-CSRTT). During testing, random and varying delays were introduced between the main house-light presentation and illumination of the ports, and premature nose-poking responses, (i.e. responses before the ports were illuminated) were considered an indicator of waiting impulsivity. As delays grew longer, animals performed more premature responses. However, previously stressed animals were 25% less likely to perform such actions by the longest delay. These studies show that early stress exposure enhanced the capacity to wait to perform a response, which is unrelated to aggression. Aspects of perseverance were tested in additional studies. In summary, chronic social stress exposure in early adolescence causes a variety of behavioral changes including enhanced aggression, decreased action inhibition and improved waiting impulsivity. This ambiguous relation between aggressive and impulsive behaviors suggests that perhaps there are multiple types of impulsive-aggression profiles related to different brain mechanisms. Thus, it is proposed that the concept of aggression should be reconsidered as a multidimensional construct mediating aspects of personality.Psycholog

Historia de la agroecología en México

A mediados del siglo pasado, existían dos tipos de científicos de la agronomía en México. Unos, que veían una agricultura atrasada y que había, ciegamente, que llevar hacia los avances tec- nológicos más modernos. Otros, que salían al campo y exploraban intensivamente los sistemas indígenas y campesinos. El estudiar y dar a conocer la riqueza tanto biológica como humana que albergaban estos sistemas, dio pie a la agroecología en este país. Sobra decir que varios de los pioneros de esa ciencia a nivel mundial, fueron aprendices de sistemas indígenas mexicanos. En este trabajo se hace el esfuerzo por narrar los hitos históricos más importantes en la investigación y la enseñanza de la agroecología en el pasado y en la actualidad; además, hacemos también una reflexión sobre los desafíos que enfrenta esa disciplina

Eating competence of elderly Spanish adults is associated with a healthy diet and a favorable cardiovascular disease risk profile

Eating competence (EC), a bio-psychosocial model for intrapersonal approaches to eating and food-related behaviors, is associated with less weight dissatisfaction, lower BMI, and increased HDL-cholesterol in small U.S. studies, but its relationship to nutrient quality and overall cardiovascular risk have not been examined. Prevención con Dieta Mediterránea (PREDIMED) is a 5-y controlled clinical trial evaluating Mediterranean diet efficacy on the primary prevention of cardiovascular diseases (CVD) in Spain. In a cross-sectional study, 638 PREDIMED participants (62% women, mean age 67 y) well phenotyped for cardiovascular risk factors were assessed for food intake and EC using validated questionnaires. Overall, 45.6% were eating-competent. EC was associated with being male and energy intake (P 5.6 mmol/L (0.71; 95% CI 0.51-0.98) and HDL-cholesterol or =3.4 mmol/L were 0.1). Our findings support further examination of EC as a strategy for enhancing diet quality and CVD prevention

Planck intermediate results. VIII. Filaments between interacting clusters

About half of the baryons of the Universe are expected to be in the form of filaments of hot and low density intergalactic medium. Most of these baryons remain undetected even by the most advanced X-ray observatories which are limited in sensitivity to the diffuse low density medium. The Planck satellite has provided hundreds of detections of the hot gas in clusters of galaxies via the thermal Sunyaev-Zel'dovich (tSZ) effect and is an ideal instrument for studying extended low density media through the tSZ effect. In this paper we use the Planck data to search for signatures of a fraction of these missing baryons between pairs of galaxy clusters. Cluster pairs are good candidates for searching for the hotter and denser phase of the intergalactic medium (which is more easily observed through the SZ effect). Using an X-ray catalogue of clusters and the Planck data, we select physical pairs of clusters as candidates. Using the Planck data we construct a local map of the tSZ effect centered on each pair of galaxy clusters. ROSAT data is used to construct X-ray maps of these pairs. After having modelled and subtracted the tSZ effect and X-ray emission for each cluster in the pair we study the residuals on both the SZ and X-ray maps. For the merging cluster pair A399-A401 we observe a significant tSZ effect signal in the intercluster region beyond the virial radii of the clusters. A joint X-ray SZ analysis allows us to constrain the temperature and density of this intercluster medium. We obtain a temperature of kT = 7.1 +- 0.9, keV (consistent with previous estimates) and a baryon density of (3.7 +- 0.2)x10^-4, cm^-3. The Planck satellite mission has provided the first SZ detection of the hot and diffuse intercluster gas.Comment: Accepted by A&