Superradiance and exciton delocalization in bacterial photosynthetic light-harvesting systems.

LH-2 complexes of Rhodobacter sphaeroides and on the isolated B820 subunit of Rhodospirillum rubrum. From these measurements the superradiance is calculated, which is related to the delocalization of excitations in these complexes. In the B820 preparation we find a radiative rate that is 30 % higher than that of monomeric bacteriochlorophyll, in agreement with a dimer model of this subunit. At room temperature both LH-1 and LH-2 are superradiant relative to monomeric Bchl-a with enhancement factors of 3.8 and 2.8, respectively. In LH-2 the radiative rate does not change significantly upon lowering the temperature to 4 K. LH-1 however exhibits a strong temperature dependence, giving rise to a 2.4 times higher radiative rate at 4 K relative to room temperature. From modeling of the superradiance using a Hamiltonian based on the LH-2 structure and including site inhomogeneity, we conclude that the ratio of inhomogeneity over the coupling betwee

Context Effects of Alcohol Availability at Home: Implicit Alcohol Associations and the Prediction of Adolescents' Drinking Behavior

OBJECTIVE: Recent studies suggest that the predictive effect of implicit alcohol associations is context dependent. Findings indicate that implicit associations are more easily retrieved in an alcohol-associated setting or context (e.g., bar) compared with a neutral setting. In line with this reasoning, we hypothesized that alcohol availability at home might moderate the relationship between implicit alcohol associations and future drinking behavior of adolescents. METHOD: Participants were 262 at-risk adolescents (235 boys, 27 girls, adolescents with externalizing behavioral problems) with a mean age of 14.11 years (SD = 0.86, age range: 12-16 years) at baseline. Adolescents completed a questionnaire and a modified version of the Implicit Association Test (i.e., Single Category Implicit Association Test; SC-IAT). RESULTS: Stronger implicit alcohol associations predicted increase in frequency of alcohol use, only in adolescents who indicated that alcohol was available at home. No moderating effects were found for increase in quantity of alcohol use and problematic alcohol use, suggesting that implicit alcohol associations particularly influence the decision of whether to drink in adolescence. CONCLUSIONS: The findings illustrate that the availability of alcohol in the home setting influences adolescents' implicit alcohol associations and consequently affects the frequency of alcohol use. In this way, alcohol availability at home may be an important contextual factor to consider when examining the effect of implicit alcohol associations on the future drinking behavior of adolescents

Дії, що дезорганізують роботу установ виконання покарань: співрозмірність злочину та покарання

Досліджується співрозмірність покарання за дії, що дезорганізують роботу уста­нов виконання покарань (ст. 392 КК України), із характером та ступенем суспільної небезпеки цього злочину, а також співрозмірність покарання за злочин, що розгля­дається, із покараннями за окремі злочини із суміжними складами.Исследуется соразмерность наказания за действия, которые дезорганизуют рабо­ту учреждений исполнения наказаний (ст. 392 УК Украины), с характером и уровнем общественной опасности этого преступления, а также с соразмерность наказания за расматриваемое преступление с наказаними за отдельные преступления со смежными составами.The article contains the study of adequacy of punishment for actions disorganizing work of penitentiary institutions (art. 392 of Criminal Code of Ukraine) and public danger of this crime also punishments for other crimes

Excitons in a Photosynthetic Light-Harvesting System: A Combined Molecular Dynamics/Quantum Chemistry and Polaron Model Study

The dynamics of pigment-pigment and pigment-protein interactions in light-harvesting complexes is studied with a novel approach which combines molecular dynamics (MD) simulations with quantum chemistry (QC) calculations. The MD simulations of an LH-II complex, solvated and embedded in a lipid bilayer at physiological conditions (with total system size of 87,055 atoms) revealed a pathway of a water molecule into the B800 binding site, as well as increased dimerization within the B850 BChl ring, as compared to the dimerization found for the crystal structure. The fluctuations of pigment (B850 BChl) excitation energies, as a function of time, were determined via ab initio QC calculations based on the geometries that emerged from the MD simulations. From the results of these calculations we constructed a time-dependent Hamiltonian of the B850 exciton system from which we determined the linear absorption spectrum. Finally, a polaron model is introduced to describe quantum mechanically both the excitonic and vibrational (phonon) degrees of freedom. The exciton-phonon coupling that enters into the polaron model, and the corresponding phonon spectral function are derived from the MD/QC simulations. It is demonstrated that, in the framework of the polaron model, the absorption spectrum of the B850 excitons can be calculated from the autocorrelation function of the excitation energies of individual BChls, which is readily available from the combined MD/QC simulations. The obtained result is in good agreement with the experimentally measured absorption spectrum.Comment: REVTeX3.1, 23 pages, 13 (EPS) figures included. A high quality PDF file of the paper is available at http://www.ks.uiuc.edu/Publications/Papers/PDF/DAMJ2001/DAMJ2001.pd

Which forms of child/adolescent externalizing behaviors account for late adolescent risky sexual behavior and substance use?

Background: Health risk behaviors like substance use (alcohol, tobacco, soft/hard drugs) and risky sexual behavior become more prevalent in adolescence. Children with behavior problems are thought to be prone to engage in health risk behaviors later in life. It is, however, unclear which problems within the externalizing spectrum account for these outcomes. Methods: Three hundred and nine children were followed from age 4/5 years to 18 years (14-year follow-up). Level and course of parent-rated opposition, physical aggression, status violations and property violations were used to predict adolescent-reported substance use and risky sexual behavior at age 18 years. Results: Both level and change in physical aggression were unique predictors of all forms of adolescent health risk behavior. Levels of status violations predicted smoking and soft drug use only, while change in property violations predicted each of the health risk behaviors. The links between opposition and health risk behaviors were accounted for by co-occurring problem behaviors. Conclusions: Of externalizing problems, physical aggression is the best predictor of adolescent substance use and risky sexual behavior from childhood onwards. Possible explanations and implications of these findings, and future research directions are discussed. © 2007 The Authors

Народное образование крымских татар в конце XIX - начале XX вв.: история и опыт в свете модернизации высшего образования Украины

Процесс модернизации высшего образования Украины проходит параллельно с процессом интеграции крымскотатарского населения в гражданское общество Украины.Процес модернізації вищого утворення України проходить паралельно з процесом інтеграції кримськотатарського населення в цивільне суспільство України

Quantum entanglement in photosynthetic light harvesting complexes

Light harvesting components of photosynthetic organisms are complex, coupled, many-body quantum systems, in which electronic coherence has recently been shown to survive for relatively long time scales despite the decohering effects of their environments. Within this context, we analyze entanglement in multi-chromophoric light harvesting complexes, and establish methods for quantification of entanglement by presenting necessary and sufficient conditions for entanglement and by deriving a measure of global entanglement. These methods are then applied to the Fenna-Matthews-Olson (FMO) protein to extract the initial state and temperature dependencies of entanglement. We show that while FMO in natural conditions largely contains bipartite entanglement between dimerized chromophores, a small amount of long-range and multipartite entanglement exists even at physiological temperatures. This constitutes the first rigorous quantification of entanglement in a biological system. Finally, we discuss the practical utilization of entanglement in densely packed molecular aggregates such as light harvesting complexes.Comment: 14 pages, 7 figures. Improved presentation, published versio

Effectiveness of the universal prevention program 'Healthy School and Drugs': Study protocol of a randomized clustered trial

Contains fulltext : 90260.pdf (publisher's version ) (Open Access)Background: Substance use is highly prevalent among Dutch adolescents. The Healthy School and Drugs program is a nationally implemented school-based prevention program aimed at reducing early and excessive substance use among adolescents. Although the program's effectiveness was tested in a quasi-experimental design before, many program changes were made afterwards. The present study, therefore, aims to test the effects of this widely used, renewed universal prevention program. Methods/Design: A randomized clustered trial will be conducted among 3,784 adolescents of 23 secondary schools in The Netherlands. The trial has three conditions; two intervention conditions (i.e., e-learning and integral) and a control condition. The e-learning condition consists of three digital learning modules (i.e., about alcohol, tobacco, and marijuana) that are sequentially offered over the course of three school years (i.e., grade 1, grade 2, and grade 3). The integral condition consists of parental participation in a parental meeting on substance use, regulation of substance use, and monitoring and counseling of students' substance use at school, over and above the three digital modules. The control condition is characterized as business as usual. Participating schools were randomly assigned to either an intervention or control condition. Participants filled out a digital questionnaire at baseline and will fill out the same questionnaire three more times at follow-up measurements (8, 20, and 32 months after baseline). Outcome variables included in the questionnaire are the percentage of binge drinking (more than five drinks per occasion), the average weekly number of drinks, and the percentage of adolescents who ever drunk a glass of alcohol and the percentage of adolescents who ever smoked a cigarette or a joint respectively for tobacco and marijuana. Discussion: This study protocol describes the design of a randomized clustered trial that evaluates the effectiveness of a school-based prevention program. We expect that significantly fewer adolescents will engage in early or excessive substance use behaviors in the intervention conditions compared to the control condition as a direct result of the intervention. We expect that the integral condition will yield most positive results, compared with the e-learning condition and control condition.10 p

A COUP-TFII Human Embryonic Stem Cell Reporter Line to Identify and Select Atrial Cardiomyocytes

Stem cells & developmental biolog