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Achieving a high degree of exfoliation in epoxy-based polymer layered silicate (PLS) nanocomposites is crucial to their successful industrial application, but has hitherto proved elusive. In this work, a system is presented which shows significant promise in this respect. The isothermal cure of PLS nanocomposites based upon a tri-functional epoxy resin (TGAP) has been studied by DSC, and displays two exothermic peaks. The first peak, very rapid, relates to a homopolymerization reaction within the intra-gallery regions, while the second peak reflects the bulk crosslinking reaction. The occurrence of the intra-gallery reaction before the bulk reaction enhances the degree of exfoliation in the cured nanocomposite. Furthermore, pre-conditioning the resin/clay mixture before adding the curing agent and effecting the isothermal cure also allows a greater extent of intra-gallery reaction to occur before the extra-gallery epoxy-amine reaction. Consequently, this system results in a high degree of exfoliation, as revealed by transmission electron microscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

We present the first quantitative data on the genetic breeding system of a lark (Alaudidae), the Skylark Alauda arvensis. Using a set of eight microsatellite loci isolated in a variety of passerine species, we genotyped 171 offspring from 52 broods of Skylark and detected 35 extra-pair offspring (20%), in 14 different broods (27%). All offspring matched their putative mother, so there was no evidence of intraspecific brood parasitism. Previous non-genetic studies had suggested that the species was predominantly socially monogamous, with only rare occurrences of social polygyny and polyandry, although some behaviours, such as mate guarding, did suggest the possibility of extra-pair copulations. The relatively high level of extra-pair paternity in this species is likely to affect the variation in male reproductive success because extra-pair paternity was non-randomly distributed amongst males, with those with shorter wings more likely to be cuckolded. [ABSTRACT FROM AUTHOR]

Mating in Deroceras consists of an investigation phase (precourtship), then a long courtship involving mutual stroking with the extruded sarcobelum, then sperm exchange (copulation). The penial gland, if present, everts over the partner's skin during copulation: this is hypothesised to apply a secretion manipulating the partner to use received sperm. Deroceras gorgonium has a particularly large penial gland divided into many finger-like branches. We studied D. gorgonium mating behaviour in the hope of further indications of the gland's function. Precourtship and courtship together last longer than in other Deroceras (ca. 6 h to >9 h); precourtship is highly variable, often with many bouts of different behaviours, including seemingly inactive phases. During most of the courtship partners remain apart waving their particularly long, pointed sarcobela; only at a later stage do the tips of these contact the partner. This waving alternates with circling for half a turn. For the first time in Deroceras we observed the sarcobelum transferring a secretion. The copulation is amongst the fastest: genital eversion and sperm exchange occur within 1 s, and slugs separate 18-25 s later. The penial gland is everted immediately after sperm exchange, but, surprisingly, is often spread underneath the partner rather than over its back and, if on top, is not always fully spread over the partner's body. We discuss these observations with respect to penial gland morphology and in the light of possible sexual conflicts. The long courtship and distant sarcobelum waving might reflect attempts to transfer, but not receive, secretion, and the circling might serve for size assessment. [ABSTRACT FROM AUTHOR]

I used optimality modelling to compare two of the most plausible and general explanations for the dawn and dusk peaks in bird song output. Kacelnik''s explanation is that foraging is inefficient in poor light, but that social interactions are less affected, making singing more worthwhile than foraging. McNamara et al.''s explanation is based on stochasticity in foraging success and overnight energy requirements; it has been extensively analysed with stochastic dynamic programming models. Both explanations are now incorporated into this sort of model. I used various functions to link success of foraging and singing to time of day, but assumed that above some light level there is no further effect. Kacelnik''s explanation has as strong an effect as stochasticity in generating dawn and dusk choruses. It also predicts short pauses in the singing output just after the dawn chorus and before the dusk chorus. The former arises because birds delay foraging when it will become more profitable later, until foraging success reaches a plateau, when the energetic debt accumulated makes them forage. The principle of this see-saw double switch in behaviours may apply to other explanations for the dawn chorus, and to other shifts in behaviour when conditions change gradually. The model predicts that from day to day cloud cover determines when a dawn chorus starts, but that overnight temperature and wind strength have more effect on chorus intensity and duration. I discuss what sort of observational and experimental data on singing routines would better test this model. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved. [Copyright &y& Elsevier]

The article presents a study in the U.S. which examines the hypernasility of mentally retarded persons. The researchers evaluated the acoustic and perceptual correlates of velophryngeal competency in two groups of retarded and one group of nonretarded individuals. Results if perceptual and acoustic analyses revealed that those persons with Down Syndrome were significantly hypernasal than the other group.

The purpose of this study was to assess the effects of oral sensory deprivation upon the aerodynamic characteristics of consonant production. Three adult males with normal speech served as subjects and read a prose passage containing at least three occurences of 13 different stops and fricatives in a syllable-initial stressed position. Sensory deprivation was achieved through a series of nerve-block injections. Intraoral air pressure was obtained using a catheter passed through the nasal cavity. Air flow rate data were obtained using a tightly fitting face mask coupled to a pneumotachograph and a differential pressure transducer system. The results indicated that, during sensory deprivation, the intraoral air pressures, intraoral air pressure durations, and air flow rates were consistently higher than during the control condition. Very few qualitative changes in the aerodynamic patterns were observed during oral anesthesia. These results were interpreted as evidence of a mixed motor control model of speech. The temporal sequencing aspect of speech appears to be feedback independent. However, the elevated aerodynamic parameters were conceived as executive adjustments to provide increased sensory data necessary for precision in reaching appropriate articulatory targets. [ABSTRACT FROM AUTHOR]

A technique has been developed to measure the linear mass density of fibers and ribbons, and adapted to the study of stress/strain coupled diffusion in polymeric materials. The technique overcomes the limitations of sensitivity and range, typical of traditional diffusion measurement techniques, and can be used for a wide range of fiber densities. It is also possible to monitor stress or strain within the fiber while measuring the change in mass, without requiring the fiber to be at equilibrium or interrupting the experiment. Estimates of material property changes, as exemplified by tensile modulus changes, can also be made during the course of the experiment. The mass per unit length, at any given time, of polymer fibers or ribbons under known stresses and strains can be determined by this technique. From this it is possible to estimate the gain or loss in weight in the sample due to permeants diffusion. Some preliminary result of constant strain and constant stress experiments on ribbons of polycarbonate, polyimide, and precured epoxy, and KevlarR monofilaments, are discussed and the scope and resolution of the apparatus are indicated. [ABSTRACT FROM AUTHOR]

To quantify the resource use of revising breast cancer screening guidelines to include average-risk women aged 40–49 years across Canada from 2024 to 2043 using a validated microsimulation model.OncoSim-Breast microsimulation platform was used to simulate the entire Canadian population in 2015–2051.We compared resource use between current screening guidelines (biennial screening ages 50–74) and alternate screening scenarios, which included annual and biennial screening for ages 40–49 and ages 45–49, followed by biennial screening ages 50–74. We estimated absolute and relative differences in number of screens, abnormal screening recalls without cancer, total and negative biopsies, screen-detected cancers, stage of diagnosis, and breast cancer deaths averted.Compared with current guidelines in Canada, the most intensive screening scenario (annual screening ages 40–49) would result in 13.3% increases in the number of screens and abnormal screening recalls without cancer whereas the least intensive scenario (biennial screening ages 45–49) would result in a 3.4% increase in number of screens and 3.8% increase in number of abnormal screening recalls without cancer. More intensive screening would be associated with fewer stage II, III, and IV diagnoses, and more breast cancer deaths averted.Revising breast cancer screening in Canada to include average-risk women aged 40–49 would detect cancers earlier leading to fewer breast cancer deaths. To realize this potential clinical benefit, a considerable increase in screening resources would be required in terms of number of screens and screen follow-ups. Further economic analyses are required to fully understand cost and budget implications. [ABSTRACT FROM AUTHOR]

The use of coupling agents to enhance the thermal conductivity of composites of epoxy and boron nitride (BN) has been investigated. Two types of BN particles, lightly aggregated platelets with an average size of 6 µm and agglomerates with an average size of 120 µm, have been used. Different proportions of these BN particles, up to a volume percentage of approximately 34%, were mixed with a stoichiometric epoxy–thiol system and cured either isothermally or non-isothermally. The cure kinetics was investigated by differential scanning calorimetry, and the thermal conductivity of isothermally fully cured samples was measured. The effect of surface treatment of the particles was extensively investigated, with respect to the characteristics of the particles themselves, the cure kinetics and the thermal conductivity of the cured composites. The BN particles were treated with a silane coupling agent, both with and without previously treating the BN with a sodium hydroxide solution. Infrared spectroscopy and thermogravimetric analysis were used to assess whether or not the silane had been attached to the BN particles, and the effect of the surface treatment on the cure kinetics was studied. Although the cure kinetics suggested that the surface treatment was more effective for the 6 µm particles than for the 120 µm agglomerates, it did not generally lead to an increase in the thermal conductivity, while scanning electron microscopy showed that the coupling agent was not attached to the BN particles. It is concluded that truly platelet-shaped particles are necessary for effective surface treatment. [ABSTRACT FROM AUTHOR]