Electroabsorption spectroscopy of single walled nanotubes

ManuscriptWe have measured the electric field modulated absorption of a sample of single-walled nanotubes (SWNT) suspended in a solid polyvinyl alcohol matrix. The electroabsorption (EA) spectrum roughly follows the first derivative of the absorption with respect to photon energy, scales quadratically with the electric field strength, and shows a pronounced anisotropy of light polarization with respect to the applied electric field direction. These findings indicate a quadratic Stark effect caused by a change in the polarizability of the excited states, which is common to quasi-one dimensional (1D) excitons in organic semiconductors. The EA spectrum is well described by calculations involving electron-electron interaction in the model Hamiltonian of both zigzag and chiral nanotubes. We have calculated the EA spectra for both zigzag and chiral nanotubes within a model Hamiltonian that includes electron-electron interactions. The calculations reproduce the observed quadratic Stark shift of the lowest optical exciton, as well as the more complicated behavior of the EA spectrum in the energy region that corresponds to the next higher exciton. Our findings show that the low-lying absorption bands in semiconducting SWNT are excitonic in origin, in agreement with transient optical measurements that identify the primary photoexcitations in SWNT as quasi-1D excitons with a substantial binding energy

Concordant cues in faces and voices: testing the backup signal hypothesis

Information from faces and voices combines to provide multimodal signals about a person. Faces and voices may offer redundant, overlapping (backup signals), or complementary information (multiple messages). This article reports two experiments which investigated the extent to which faces and voices deliver concordant information about dimensions of fitness and quality. In Experiment 1, participants rated faces and voices on scales for masculinity/femininity, age, health, height, and weight. The results showed that people make similar judgments from faces and voices, with particularly strong correlations for masculinity/femininity, health, and height. If, as these results suggest, faces and voices constitute backup signals for various dimensions, it is hypothetically possible that people would be able to accurately match novel faces and voices for identity. However, previous investigations into novel face–voice matching offer contradictory results. In Experiment 2, participants saw a face and heard a voice and were required to decide whether the face and voice belonged to the same person. Matching accuracy was significantly above chance level, suggesting that judgments made independently from faces and voices are sufficiently similar that people can match the two. Both sets of results were analyzed using multilevel modeling and are interpreted as being consistent with the backup signal hypothesis

Estimating the duration of speciation from phylogenies

Speciation is not instantaneous but takes time. The protracted birth-death diversification model incorporates this fact and predicts the often observed slowdown of lineage accumulation toward the present. The mathematical complexity of the protracted speciation model has barred estimation of its parameters until recently a method to compute the likelihood of phylogenetic branching times under this model was outlined (Lambert et al. ). Here, we implement this method and study using simulated phylogenies of extant species how well we can estimate the model parameters (rate of initiation of speciation, rate of extinction of incipient and good species, and rate of completion of speciation) as well as the duration of speciation, which is a combination of the aforementioned parameters. We illustrate our approach by applying it to a primate phylogeny. The simulations show that phylogenies often do not contain enough information to provide unbiased estimates of the speciation-initiation rate and the extinction rate, but the duration of speciation can be estimated without much bias. The estimate of the duration of speciation for the primate clade is consistent with literature estimates. We conclude that phylogenies combined with the protracted speciation model provide a promising way to estimate the duration of speciation.</p

Evaluating the clinical and economic burden of healthcare-associated infections during hospitalization for surgery in France

Over 4 million patients suffer nosocomial infections annually in the European Union. This study aimed to estimate the healthcare burden associated with healthcare-associated infections (HAIs) following surgery in France, and explore the potential impact of infection control strategies and interventions on the clinical and economic burden of disease. Data on the frequency of HAIs were gathered from the 2010 Programme de Médicalisation des Systèmes d'Information (PMSI), and cost data were taken from the 2009 Echelle Nationale de Coûts à Méthodologie Commune (ENCC). It was estimated that 3% of surgical procedures performed in 2010 in France resulted in infection, resulting in an annual cost of €57892715. Patients experiencing a HAI had a significantly increased mortality risk (4·15-fold) and an increased length of hospital stay (threefold). Scenario analysis in which HAI incidence following surgery was reduced by 8% (based on a study of the effectiveness of triclosan-coated sutures), suggested that, annually, 20205 hospital days and €4588519 could be saved. Analyses of 20% and 30% reductions in incidence (based on an estimate of the number of preventable nosocomial infections) suggested that annual savings of €11548057 and €17334696, respectively, could be made. New infection control interventions which reduce HAI incidence during hospitalization for surgery have the potential to provide valuable cost savings to healthcare provider

Molecular and morphometric variation in European populations of the articulate brachiopod <i>Terebeatulina retusa</i>

Molecular and morphometric variation within and between population samples of the articulate brachiopod &lt;i&gt;Terebratulina&lt;/i&gt; spp., collected in 1985-1987 from a Norwegian fjord, sea lochs and costal sites in western Scotland, the southern English Channel (Brittany) and the western Mediterranean, were measured by the analysis of variation in the lengths of mitochondrial DNA (mtDNA) fragments produced by digestion with nine restriction endonucleases and by multivariate statistical analysis of six selected morphometric parameters. Nucleotide difference within each population sample was high. Nucleotide difference between population samples from the Scottish sites, both those that are tidally contiguous and those that appear to be geographically isolated, were not significantly different from zero. Nucleotide differences between the populations samples from Norway, Brittany, Scotland and the western Mediterranean were also very low. Morphometric analysis confirmed the absence of substantial differentiation

Hydrodynamic and Aerodynamic Tests of Models of Flying-boat Hulls Designed Flow Aerodynamic Drag - NACA Models 74, 74-A, and 75

The present tests illustrate how the aerodynamic drag of a flying boat hull may be reduced by following closely the form of a low drag aerodynamic body and the manner in which the extent of the aerodynamic refinement is limited by poorer hydrodynamic performance. This limit is not sharply defined but is first evidenced by an abnormal flow of water over certain parts of the form accompanied by a sharp increase in resistance. In the case of models 74-A and 75, the resistance (sticking) occurs only at certain combinations of speed, load, and trim and can be avoided by proper control of the trim at high water speeds. Model 75 has higher water resistance at very high speeds than does model 74-A. With constant speed propellers and high takeoff speeds, it appears that the form of model 75 would give slightly better takeoff performance. Model 74-A, however, has lower aerodynamic drag than does model 75 for the same volume of hull

Confident, fearful and hopeless cooks: Findings from the development of a food-skills initiative

One of the many barriers to a healthier diet in low-income communities is a presumed lack of practical food skills. This article reports findings from exploratory qualitative research conducted with potential participants in a cooking skills intervention, in low income communities in Scotland. The research found widely varying levels of skill and confidence regarding cooking, supported the need for a community-based intervention approach, and demonstrated the importance of consumer research to inform the content of interventions. Challenges the view that low income communities lack skills, suggesting that food skills should be defined more broadly than “cooking from scratch”. Other barriers to healthy eating, such as poverty, food access and taste preferences, remain important