Collision of One-Dimensional Nonlinear Chains

We investigate one-dimensional collisions of unharmonic chains and a rigid wall. We find that the coefficient of restitution (COR) is strongly dependent on the velocity of colliding chains and has a minimum value at a certain velocity. The relationship between COR and collision velocity is derived for low-velocity collisions using perturbation methods. We found that the velocity dependence is characterized by the exponent of the lowest unharmonic term of interparticle potential energy

Variación estacional de las taxocenosis de Odonatos, Coleópteros y Heterópteros acuaticos en algunos ecosistemas del bajo Guadalquivir (Sw. España) durante un ciclo anual

Se describe, cualitativa y cuantitativamente, la estructura de las taxocenosis de larvas de Odonatos y larvas y adultos de Heterópteros y Coleópteros acuáticos en relación con el medio abiótico en el que se desarrollan, así como la variación estacional de la misma. El estudio se realizó en los años 1977 y 1978 de una fuma comparativa para cuatro estaciones de muestreo (Lucio del Aro, Caiio Travieso, Laguna de Santa Olalla y 'Laguna de Medina), con diferencias en: permanencia de las aguas, rangos de clorosidad y relaciones de localizacion geogrzífica con cuerpos de agua vecinos. Las tres primeras estaciones pertenecen al Parque Nacional de Doñana. Finalmente, se resumen de forma genera1 algunos aspectos ecológicos en relación con la estructura estacional de los cuatro medios acuáticos considerados.On a étudié, de maniere qualitative et quantitative, la structure des populations de larves d'Odonates et larves et images de Heteropteres et Coleoptéres aquatiques, en rapport avec le milieu abiotique, ainsi que la variation saisonniére de cette structure biotique. Le période d'étude á compris le cycle annuel entre les années 1977 et 1978. L'étude a été réalisé, de fafon comparative, dans quatre statlons d'échantillonnage (Lucio du Aro, Caño Travieso, Lacune de Sta. Olíala et Lacune de Medina) oü les différences plus importances sont: la longueur de la permanence de l'eau, les ranges de la clorosité et las relations de localisation géographique avec milieux aquatiques prochains. Les trois premieres stations d'échantillonnage appartiennent au Pare National de Doñana. Finalement, on resume en general quelques aspects écologiques, qui ont rapport á la structure saisonniére des quatre ecosystémes aquatiques consideres

Las taxocenosis de coleópteros acuáticos como indicadores ecológicos en el río Rivera de Huelva (Sevilla): Aspectos metodológicos

Se ha realizado un estudio ecológico descriptivo, con técnicas de muestreo estratificado y selectivo, de los biotopos acuáticos del río Rivera de Huelva (Sevilla), mediante la aplicación de técnicas de análisis factorial a las abundancias relativas de las taxocenosis de coleópteros acuáticos y a las medidas de nueve factores físico-químicos del medio (altura sobre el nivel del mar, corriente, profundidad, trainsparencia, temperatura del agua, pH, alcalinidad, cloruros y oxígeno). Se han determinado un total de 59 especies, pertenecientes a ocho familias de coleópteros acuáticos. Los biotopos acuáticos estudiados presentan un gradiente de variación, cuyos extremos vienen, marcados por la altura, corriente, contenido en oxígeno y transparencia, frente a profundidad, temperatura del agua, pH, alcalinidad y cloruros. No ha sido posible obtener grupos de coleópteros acuáticos de claro valor indicador, debido a que los biotopos acuáticos estudiados muestran una marcada diversificación en microhabitats a la que responden, fundamentalmente en cuanto a disponibilidad del alimento, los organismos estudiados. El muestreo homogeneizado en todo el biotopo no ha permitido detectar estas características. Se insiste en los aspectos metodológicos referentes al muestreo, al tratamiento de la información y a la selección de la unidad ecológica en la que realizar medidas de factores físico-químicos y estimas de abundancia de las taxocenosis que van a ser estudiadas.On a fait une étude écologique descriptive des biotopos aquatiques du fleuve Rivera de Huelva (Séville), par des techniques d'échantillonnage stratifié et sélectif, moyennant l'application de techniques d'analyses factorielles («factor analysis») aux abondances relatives des taxocénoses de coléoptéres aquatiques et aux mesures de neuf facteurs physico-chimiques du milieu (hauteur sur le niveau de la mer, courants, profondeur, transparence, température de l'eau, pH, alcalinité, chlorures et oxygéne). Les biotopos aquatiques étudiés présentent un gradient de variation dont les extremes sont marqués par la hauteur, les courants, la quantité d'oxygéne et la transparence face a la profondeur, la température de l'eau, pH, l'alcalinité et les chlorures. II nous a été impossible d'obtenir des groupes de coléoptéres aquatiques d'une claire valeur indicative, dü á ce que les biotopos aquatiques étudiés montrent une diversification tres marquée en microhabitats. Les organismes étudiés répondent a la dite diversification quant a la disponibilité de la nourriture fondamentalement. L'échantillonnage homogéneisé dans tout le biotopo nous a empéché de détecter ees caractéristiques. On a insiste sur les aspects méthodologiques, référants a l'échantillonnage, sur le traitement de l'information et sur la sélection de l'unité écologique oü l'on réalise des mesures de facteurs physico-chimiques et des estimes d'abondance des taxocénosesétudiées

Explaining the Higgs Decays at the LHC with an Extended Electroweak Model

We show that the recent discovery of a new boson at the LHC, which we assume to be a Higgs boson, and the observed enhancement in its diphoton decays compared to the SM prediction, can be explained by a new doublet of charged vector bosons from an extended electroweak gauge sector model with SU(3)_C\otimesSU(3)_L\otimesU(1)_X symmetry. Our results show a good agreement between our theoretical expected sensitivity to a 126--125 GeV Higgs boson and the experimental significance observed in the diphoton channel at the 8 TeV LHC. Effects of an invisible decay channel for the Higgs boson are also taken into account, in order to anticipate a possible confirmation of deficits in the branching ratios into $ZZ^*$, $WW^*$, bottom quarks, and tau leptons.Comment: 16 pages, 5 figure

Subtelomeric I-scei-mediated Double-strand Breaks Are Repaired By Homologous Recombination In Trypanosoma Cruzi

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Trypanosoma cruzi chromosome ends are enriched in surface protein genes and pseudogenes (e.g., trans-sialidases) surrounded by repetitive sequences. It has been proposed that the extensive sequence variability among members of these protein families could play a role in parasite infectivity and evasion of host immune response. In previous reports we showed evidence suggesting that sequences located in these regions are subjected to recombination. To support this hypothesis we introduced a double-strand break (DSB) at a specific target site in a T. cruzi subtelomeric region cloned into an artificial chromosome (pTAC). This construct was used to transfect T. cruzi epimastigotes expressing the I-SceI meganuclease. Examination of the repaired sequences showed that DNA repair occurred only through homologous recombination (HR) with endogenous subtelomeric sequences. Our findings suggest that DSBs in subtelomeric repetitive sequences followed by HR between them may contribute to increased variability in T. cruzi multigene families. © 2016 Chiurillo, Moraes Barros, Souza, Marini, Antonio, Cortez, Curto, Lorenzi, Schijman, Ramirez and da Silveira.7DEC11/51475-3, FAPESP, Fundação de Amparo à Pesquisa do Estado de São Paulo11/51693-0, FAPESP, Fundação de Amparo à Pesquisa do Estado de São Paulo306591/2015-4, CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Dietary patterns in an elderly population and their relation with bone mineral density: the Rotterdam Study

Purpose: Our aim was to identify dietary patterns that are associated with bone mineral density (BMD) against a background of relatively high dairy intake in elderly Dutch subjects. Methods: Participants were 55 years of age and older (n = 5144) who were enrolled in The Rotterdam Study, a population-based prospective cohort study. Baseline intake of 28 pre-defined food groups was determined using a validated food frequency questionnaire. Dietary patterns were identified using principal component analysis. BMD was measured using dual-energy X-ray absorptiometry at baseline and at three subsequent visits (between 1993 and 2004). Linear mixed modelling was used to longitudinally analyse associations of adherence to each pattern with repeatedly measured BMD (both in Z scores). Results: After adjustment for confounders, two dietary patterns were associated with high BMD: a “Traditional” pattern, characterized by high intake of potatoes, meat and fat (β = 0.06; 95 % CI 0.03, 0.09) and a “Health conscious” pattern, characterized by high intake of fruits, vegetables, poultry and fish (β = 0.06; 95 % CI 0.04, 0.08). The “Processed” pattern, characterized by high intake of processed meat and alcohol, was associated with low BMD (β = −0.03; 95 % CI −0.06, −0.01). Associations of adherence to the “Health conscious” and “Processed” pattern with BMD were independent of body weight and height, whereas the association between adherence to the “Traditional” pattern with BMD was not. Conclusions: Against a background of high dairy intake and independent of anthropometrics, a “Health conscious” dietary pattern may have benefits for BMD, whereas a “Processed” dietary pattern may pose a risk for low BMD

Association between an insulin-like growth factor I gene promoter polymorphism and bone mineral density in the elderly: the Rotterdam Study

Studies of the roles of variants of the IGF-I gene in the regulation of bone mineral density (BMD) have yielded conflicting results. We examined the role of a microsatellite repeat polymorphism in one of the promoter regions of the IGF-I gene in relation to femoral BMD in elderly women and men from the Rotterdam Study. We studied 5648 and 4134 individuals at baseline and follow-up ( approximately 2 yr later), respectively. Femoral BMD measurements were performed using dual energy x-ray absorptiometry. In women, baseline BMD levels were, on the average, 0.02 g/cm(2) [95% confidence interval (CI) for difference, -0.03, -0.00 g/cm(2)] lower in individuals without the 192-bp allele as compared with the homozygotes for the allele (P = 0.03). The mean rate of BMD change from baseline to follow-up was -6.9 mg/cm(2) (95% CI, -10.8, -3.0), -4.5 mg/cm(2) (95% CI, -6.4, -2.5), and -2.3 mg/cm(2) (95% CI, -4.2, 0.3) in noncarriers, heterozygotes, and homozygotes for the 192-bp allele, respectively (P trend = 0.03). Adjustment for age and body mass index did not essentially change this relation. No such effects were observed in men. Our findings suggest that this promoter polymorphism or another functional polymorphism in linkage disequilibrium may be a genetic determinant of BMD levels and rate of bone loss in postmenopausal women

Bone health and coronary artery calcification: The Rotterdam Study

Objectives: Vascular calcification has been associated inconsistently to low bone mineral density and fractures. The aims of the present study were to investigate the associations between coronary artery calcification (CAC) and BMD change, BMD and fracture risk in elderly subjects of the population-based Rotterdam Study. Methods: BMD was assessed through dual-energy X-ray absorptiometry and CAC through Electron-Beam Computed Tomography in 582 men and 694 women. We investigated the associations between BMD change (6.4 years follow-up) and CAC at follow-up and between BMD and CAC (measured simultaneously). In sensitivity analyses we stratified analyses for estradiol levels in women. The association between CAC and fracture risk (9 years follow-up) was tested through competing-risks models. Models were sex-stratified and adjusted for age, body mass index, smoking, bisphosphonate use and age at menopause. Results: There was no association between BMD change and CAC in men. In women, each 1% increase in annual BMD loss was significantly associated with higher follow-up CAC [β = 0.22 (0.06-0.38), p. =. 0.006; prevalence ratio: 4%]. Stratified analyses showed significant associations between BMD loss and follow-up CAC only in women with lower estradiol levels. We found no association between CAC and fracture risk and no association between BMD and CAC cross-sectionally. Conclusions: BMD loss was associated with higher follow-up CAC in women, which might be related to low estrogen levels. No association between CAC and BMD or fracture risk was found. Further studies are required to elucidate the mechanisms that might underlie the association between BMD change and coronary calcification in women

De genetica van ondernemerschap

genetiGenoombreed associatieonderzoek is een moderne onderzoeksmethode die het mogelijk maakt genen te vinden die geassocieerd zijn met allerlei ziekten en menselijke eigenschappen. Een samenwerkingsverband tussen de Erasmus School of Economics en het Erasmus Medisch Centrum probeert deze veelbelovende methode toe te passen op de keuze voor ondernemerschap