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Quantifying the physical mechanisms responsible for the transport of sediments, nutrients and pollutants in the abyssal sea is a long-standing problem, with internal waves regularly invoked as the relevant mechanism for particle advection near the sea bottom. This study focuses on internal-wave-induced particle transport in the vicinity of (almost) vertical walls. We report a series of laboratory experiments revealing that particles sinking slowly through a monochromatic internal wave beam experience significant horizontal advection. Extending the theoretical analysis by Beckebanze et al. (J. Fluid Mech., vol. 841, 2018, pp. 614–635), we attribute the observed particle advection to a peculiar and previously unrecognized streaming mechanism in the stratified boundary layer originating at the lateral walls. This vertical boundary layer streaming mechanism is most efficient for significantly inclined wave beams, when vertical and horizontal velocity components are of comparable magnitude. We find good agreement between our theoretical prediction and experimental results.
Geomorphic evidence of past glaciation, such as U-shaped valleys, aretes, glacial lakes, and moraines, is preserved in the highland surrounding Cerro Chirripó in the Cordillera de Talamanca, Costa Rica. Previous work to establish a glacial chronology has focused on relative age dating of moraines and on radiocarbon dating of basal lake sediments to infer the timing of deglaciation. We used cosmogenic 36Cl surface exposure dating to constrain the ages of moraines within two formerly glaciated valleys, the Morrenas and Talari valleys. Forty-nine boulder samples were processed and measured from four moraine complexes in the Morrenas Valley and two moraine complexes in the Talari Valley. The exposure ages of these samples indicate a major glacial event occurred in this area from ~25 to 23 ka, broadly synchronous with the global last glacial maximum. Our results also indicate periods of glacial retreats and standstills from the deglacial period to the Early Holocene (~16–10 ka) before the complete disappearance of glaciers in this highland. These findings provide important insights into the glacial chronology and paleoclimate of tropical America.
Thin-section (micromorphological) analysis of samples from the upper 1.5 m of a core obtained in 2007 from Anderson Pond, Tennessee, reveals a coherent but discontinuous record of late Pleistocene and Holocene climate change that supports some interpretations from previous pollen and charcoal analyses but indicates a revised Holocene chronology for this classic pollen site. Legacy sediments recording anthropogenic disturbance compose the upper 65 cm of the core (<160 cal yr BP) and are characterized by mixed, darker-colored, and coarser-grained deposits containing reworked soil aggregates, which sharply overlie finer-grained and lighter-colored, rooted middle Holocene sediments interpreted as a paleosol. These mid-Holocene sediments (95–65 cm; 7100–5600 cal yr BP) record extensive warm-dry subaerial soil conditions during the middle Holocene thermal maximum, manifested by illuviated clay lining root pores, and also contain abundant charcoal. Late Pleistocene sediments (150–95 cm), dark-colored and organic-rich, record open-water conditions and include siliceous aggregate grains at 143–116 cm (14,300–13,900 cal yr BP), recording intense fires. Thin sections are not commonly used in studies of paleoclimate from Quaternary lacustrine sediments, but we advocate for their inclusion in multianalytical approaches because they enhance resolution of depositional and pedogenic processes.
Il est aujourd’hui clairement établi que les patients souffrant de schizophrénie présente un risque plus élevé de violence que la population générale. Différents facteurs de risque de violence ont été mis en évidence chez ces patients, tels que l’impulsivité, le trouble de personnalité antisociale, les comorbidités addictives. Néanmoins, les études ayant tenté d’identifier le risque de violence des patients schizophrènes ont abouti à des résultats variables. L’hétérogénéité des gestes de violence commis, ainsi que la variabilité des profils de ces patients contribuent certainement à la divergence de ces résultats. Par ailleurs, différents auteurs ont montré que les patients présentant un délire d’identification des personnes constituaient une sous-catégorie de patients à risque de comportements violents, devenant agressifs et violents du fait du thème de leur délire. Cependant, aucune étude n’a exploré l’association entre délire d’identification et type de geste violent. Nous nous sommes donc intéressés à l’étude des caractéristiques cliniques de patients schizophrènes ayant commis des gestes de violence, à partir d’une étude descriptive réalisée sur une population de patients schizophrènes détenus. Nous avons évalué l’intensité des symptômes grâce à la Positive and Negative Symptom Scale (PANSS), la coexistence d’un trouble de personnalité antisociale et les comorbidités addictives grâce au Mini International Neuropsychiatric Interview (MINI). Le niveau d’impulsivité et les comportements violents ont été estimés par la Baratt Impulsivity Scale (BIS) et la MacArthur Community Violence Interview. Enfin, l’existence de troubles de la familiarité, tels que ceux qui caractérisent les délires d’identification des personnes, a été systématiquement recherchée. Notre objectif est, d’une part, d’évaluer de manière systématique les troubles de familiarité des patients schizophrènes, et leur association avec les comportements violents, et d’autre part, d’objectiver l’hétérogénéité des profils des patients schizophrènes ayant commis des gestes de violence.
L’association entre schizophrénie et violence a longtemps été controversée, mais les données issues des études les plus récentes établissent un lien clair entre schizophrénie et risque de violence. Néanmoins, tous les patients schizophrènes ne présentent pas un risque égal de passage à l’acte violent. Différents facteurs de risque ont ainsi pu être identifiés, tels l’intensité de la symptomatologie psychotique, l’impulsivité ou les comorbidités addictives. Récemment, différents auteurs ont émis l’hypothèse de différents sous-groupes de patients schizophrènes à risque de comportements violents : la majorité des actes commis par les patients schizophrènes représenteraient des gestes de violence mineure alors que les actes de violence majeure ne seraient commis que par une faible proportion de ces patients. Pour l’ensemble de ces patients, des difficultés persistent dans l’établissement de leur responsabilité pénale. Le code pénal français prévoit l’irresponsabilité pénale pour les personnes atteintes, au moment des faits, d’un trouble psychique ou neuropsychique ayant aboli leur discernement ou le contrôle de leurs actes. Pour autant, la reconnaissance de la responsabilité pénale des personnes atteintes de troubles mentaux semble en augmentation, augmentant ainsi le nombre de patients schizophrènes en détention. Une première partie aura pour objectif d’approfondir l’étude des facteurs de risque des comportements violents, en intégrant l’hétérogénéité des gestes de violence, à partir d’une étude descriptive de patients schizophrènes incarcérés. Une attention particulière sera portée sur les liens existant entre troubles de la familiarité et passages à l’acte violents. Une deuxième partie s’intéressera aux facteurs neurobiologiques des comportements violents des patients schizophrènes, grâce à l’étude du lien entre impulsivité et violence en imagerie par résonance magnétique fonctionnelle (IRMf). Enfin, une troisième partie abordera la question de la responsabilité de ces patients souffrant de troubles mentaux et présentant des comportements violents, et s’intéressera notamment aux nouvelles techniques d’approches expertales de la responsabilité.
The Mediterranean diet has been reported to be inversely associated with incident metabolic syndrome (MetSyn) among older adults; however, this association has not been studied in young African American and white adults. The objective of the present study was to evaluate the association of a modified Mediterranean diet (mMedDiet) score with the 25-year incidence of the MetSyn in 4713 African American and white adults enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. A diet history questionnaire was used to assess dietary intake at baseline, year 7 and year 20 and a mMedDiet score was created. Cardiovascular risk factors were measured at multiple examinations over 25 years. The MetSyn was defined according to the National Cholesterol Education Program Adult Treatment Panel III (ATP III) criteria. Cox proportional-hazards regression analysis was use to evaluate associations for incident MetSyn across the mMedDiet score categories adjusting for demographic characteristics, lifestyle factors and BMI. Higher mMedDiet scores represented adherence to a dietary pattern rich in fruit, vegetables, whole grains, nuts and fish, but poor in red and processed meat and snack foods. The incidence of MetSyn components (abdominal obesity, elevated TAG concentrations and low HDL-cholesterol concentrations) was lower in those with higher mMedDiet scores than in those with lower scores. Furthermore, the incidence of the MetSyn was lower across the five mMedDiet score categories; the hazard ratios and 95 % CI from category 1 to category 5 were 1·0; 0·94 (0·76, 1·15); 0·84 (0·68, 1·04); 0·73 (0·58, 0·92); and 0·72 (0·54, 0·96), respectively (Ptrend= 0·005). These findings suggest that the risk of developing the MetSyn is lower when consuming a diet rich in fruit, vegetables, whole grains, nuts and fish.
Imidazoles present a tunable, versatile and economical platform for the development of novel liquid solvents and polymer membranes for CO2 capture. An overview of our studies in this area is presented, with emphasis on characterization of structure-property relationships in imidazole-based materials through both experimental and computational studies. To this end, a growing library of systematically varied imidazole compounds has been synthesized using only commercial available starting materials and straightforward reactions. Using this library of compounds, we have sought to understand and develop predictive models for thermophysical properties relating to process design, including: density, viscosity, vapor pressure, pKa and CO2 absorption capacity. Furthermore, we have discovered that imidazoles are stable in the presence of SO2 and can form reversible 1:1 adducts, which can be beneficial as SO2 is typically present at ppm levels alongside CO2 in flue gas from coal-fired power plants.
The availability of genome sequence data has facilitated the development of high-throughput genetic screening approaches in microbial pathogens. In the African trypanosome, Trypanosoma brucei, genome-scale RNA interference screens have proven particularly effective in this regard. These genetic screens allow for identification of the genes that contribute to a particular pathway or mechanisms of interest. The approach has been used to assess loss-of-fitness, revealing the genes and proteins required for parasite viability and growth. The outputs from these screens predict essential and dispensable genes and facilitate drug target prioritization efforts. The approach has also been used to assess resistance to anti-trypanosomal drugs, revealing the genes and proteins that facilitate drug uptake and action. These outputs also highlight likely mechanisms underlying clinically relevant drug resistance. I first review these findings in the context of what we know about current drugs. I then describe potential contributions that these high-throughput approaches could make to the development and implementation of new drugs.
We summarize the status of a computer simulator for microlens planet surveys. The simulator generates synthetic light curves of microlensing events observed with specified networks of telescopes over specified periods of time. Particular attention is paid to models for sky brightness and seeing, calibrated by fitting to data from the OGLE survey and RoboNet observations in 2011. Time intervals during which events are observable are identified by accounting for positions of the Sun and the Moon, and other restrictions on telescope pointing. Simulated observations are then generated for an algorithm that adjusts target priorities in real time with the aim of maximizing planet detection zone area summed over all the available events. The exoplanet detection capability of observations was compared for several telescopes.
The effect of different weaning ages, that is, 21 (G21), 28 (G28) or 35 (G35) days, on growth and certain parameters of the digestive tract was examined in rabbits to assess the risk of early weaning attributable to the less-developed digestive system. On days 35 and 42, G35 rabbits had 10% to 14% and 10% higher BW, respectively (P < 0.05), than those weaned at days 21 and 28. In the 4th week of life, early weaned animals had 75% higher feed intake than G28 and G35 rabbits (P < 0.05). The relative weight of the liver increased by 62% between 21 and 28 days of age, and thereafter it decreased by 76% between 35 and 42 days of age (P < 0.05), with G21 rabbits having 29% higher weight compared with G35 animals on day 35 (P < 0.05). The relative weight of the whole gastrointestinal (GI) tract increased by 49% and 22% after weaning in G21 and G28 rabbits, respectively (P < 0.05). On day 28, the relative weight of the GI tract was 19% higher in G21 than in G28 rabbits, whereas on day 35 G21 and G28 animals had a 12% heavier GI tract compared with G35 rabbits (P < 0.05). Age influenced the ratio of stomach, small intestine and caecum within the GI tract; however, no effect of different weaning age was demonstrated. The pH value of the stomach and caecum decreased from 5.7 to 1.6 and from 7.1 to 6.3, respectively, whereas that of the small intestine increased from 6.8 to 8.4 (P < 0.05); the differences between groups were not statistically significant. Strictly anaerobic culturable bacteria were present in the caecum in high amounts (108), already at 14 days of age; no significant difference attributable to weaning age was demonstrable. The concentration of total volatile fatty acids (tVFA) was higher in G21 than in G28 and G35 throughout the experimental period (P < 0.05). The proportion of acetic and butyric acid within tVFA increased, whereas that of propionic acid decreased, resulting in a C3 : C4 ratio decreasing with age. Early weaning (G21) resulted in higher butyric acid and lower propionic acid proportions on day 28 (P < 0.05). No interaction between age and treatment was found, except in relative weight of the GI tract and caecal content. In conclusion, early weaning did not cause considerable changes in the digestive physiological parameters measured, but it resulted in 10% lower growth in rabbits.
Las Cumbres Observatory Global Telescope Network (LCOGT) is currently building a new kind of general-purpose astronomical facility: a fully robotic network of telescopes of 2m, 1m and 0.4m apertures and homogeneous instrumentation. A pan-network approach to scheduling (rather than per individual telescope) offers redundancy in the event of poor weather or technical failure, as well as the ability to observe a target around the clock. Here we describe the network design and instrumentation under development, together with the main science programmes already being lead by LCOGT staff.
Climate change during the so-called Little Ice Age (LIA) of the 15th to 19th centuries was once thought to be limited to the high northern latitudes, but increasing evidence reflects significant climate change in the tropics. One of the hypothesized features of LIA climate in the low latitudes is a more southerly mean annual position of the Intertropical Convergence Zone (ITCZ), which produced more arid conditions through much of the northern tropics. High-resolution stable oxygen isotope data and other sedimentary evidence from Laguna de Felipe, located on the Caribbean slope of the Cordillera Central of the Dominican Republic, support the hypothesis that the mean annual position of the ITCZ was displaced significantly southward during much of the LIA. Placed within the context of regional paleoclimate and paleoceanographic records, and reconstructions of global LIA climate, this shift in mean annual ITCZ position appears to have been induced by lower solar insolation and internal dynamical responses of the global climate system. Our results from Hispaniola further emphasize the global nature of LIA climate change and the sensitivity of circum-Caribbean climate conditions to what are hypothesized to be relatively small variations in global energy budgets.
Staphylococcus aureus is a leading cause of infections in deployed service members. Based on a molecular epidemiological study of 182 MRSA isolates from patients in three U.S. Army combat support hospitals in separate regions in Iraq, USA300 clone was the most predominant (80%) pulsotype. This finding suggested that strain carriage from the home country by military personnel is epidemiologically more important than local acquisition.
This study examines consumer preferences for three socially responsible products: minimal-pesticide strawberries, fair-trade bananas, and milk from pasture-fed cows. In-person survey data were collected in four states. Understanding preferences for these characteristics is difficult because they may appeal to different individuals depending on their personal attitudes and values. To address this issue, health, environmental and other attitudes are measured based on survey questions. Responses to these questions are used to produce explanatory factor scores. Stated preference models, both with and without factor scores, are estimated to evaluate the relative strengths of consumer preferences and motivations to purchase these products.
Experimental and theoretical studies were made of the decrease in the degree of ionization of shock-heated agron resulting from radiative emission. the studies were based on measurment of the time history of the electron density by means of optical interferometry used in conjunction with a rotating mirror camera. These measurments apply to the quasi-euilibrium region which follows the short electronic relaxation zone behind strong shocks. Loss of energy by rediation led to cooling of the gas as evidenced by the decreasing electron density. The analytical studies were based on the assumption that the dense plasma readiated throught both continuu, emission and emission from spectral lines. Comparison was made with experimental results, and theory and experiment were in good agreement, for a realistic choice of the parameters contained in the continuum theory. The analysis indicated that line radiation losses could not be disregarded. Sizeable loss resulted from lower level bound-bound transitions even though these lines experienced absorption.
Analyses of pollen and other terrestrial microfossils in sediment profiles from neotropical lakes can complement and extend archaeological studies by documenting the timing of prehistoric human disturbances within watersheds. However, assessing the scale of prehistoric human impact from sedimentary microfossil assemblages alone is often difficult. We explore here the utility of combining stable carbon isotope (δ13C) analyses of lake sediments and isotopie mixing models to improve our ability to gauge the extent of prehistoric human disturbance recorded in sediment profiles. Our test case involves the analysis o f a sediment core from Laguna Bonillita on the central Caribbean slope of Costa Rica that spans approximately the last 2,700 calendar years. Variations in the δ13C values of the Laguna Bonillita sediments suggest that human population growth and environmental impacts in the watershed were at their maximum ~cal yr 300 B.C. This finding is in keeping with archaeological evidence of rapid regional population growth at this time but differs from initial interpretations of the sediment record that were based on pollen and charcoal analyses alone. We believe that the use of stable carbon isotope data from sediment profiles can improve estimates of the scale of prehistoric human impact and in doing so improve the contributions of paleoecological research to archaeology.