10,032 research outputs found

    2015 Eugene Kuntz Award Ceremony: Introductory Remarks

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    Dinosaur tracks from the Kilmaluag Formation (Bathonian, Middle Jurassic) of Score Bay, Isle of Skye, Scotland, UK

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    Tracks of a juvenile theropod dinosaur with footprint lengths of between 2 and 9 cm as well as adults of the same ichnospecies with footprints of about 15–25 cm in length were found in the Bathonian (Middle Jurassic) Kilmaluag Formation of Score Bay, northwestern Trotternish Peninsula, Isle of Skye, Scotland, UK. Two footprint sizes occur together on the same bedding plane in the central portion of Score Bay, both in situ and on loose blocks. Another horizon containing footprints above this was also identified. The footprints from the lowest horizon were produced in a desiccated silty mud that was covered with sand. A close association of both adults and juveniles with similar travel direction indicated by the footprints may suggest post-hatching care in theropod dinosaurs. Other footprints, produced on a rippled sandy substrate, have been found on the slightly higher bedding plane at this locality. Loose blocks found 130 m to the northeast in the central part of Score Bay have not been correlated with any in situ sediments, but were preserved in a similar manner to those from the higher bedding plane. These tracks represent the youngest dinosaur remains yet found in Scotland

    Optimal threshold density in a stochastic resource management model with pulse intervention

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    Human activities and agricultural practices are having huge impacts on the development of fishery and land resources through different ways. To model such systems that involve harvesting, an impulsive model of natural resources with a stochastic noise perturbation element is formulated to study the relationship between (a) the maximal expectation of biomass after harvesting or fishing events and (b) the minimal expectation of pest biomass and the number of times pesticide is applied. Using a detailed analytical treatment, time estimation, and numerical demonstrations, we establish that the proposed mechanism is capable of maximizing fish populations at the end of a fishing season and minimizing pest numbers after a crop harvesting season once the intensity of the noise is relatively small. Investigations of the effects of different parameters reveal that theoretical predictions from the new stochastic model accord with those from the deterministic case

    Deaf individuals’ bilingual abilities: American Sign Language proficiency, reading skills, and family characteristics

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    The current study investigated the bilingual abilities of 55 Deaf individuals, examining both American Sign Language (ASL) competency and English reading skills. Results revealed a positive relationship between ASL competency and English skills, with highly competent signers scoring higher on a measure of reading comprehension. Additionally, family characteristics (e.g., parental education level, family hearing status) were entered into the analysis to ascertain their effect on Deaf individuals’ bilingual abilities. The findings support the theory that competency in ASL may serve as a bridge to the acquisition of English print. Moreover, the findings provide support for the critical period hypothesis for first language acquisition and its later impact on other cognitive and academic skills

    iScience: A Computer-Supported Collaborative Inquiry Learning Project for Science Students in Secondary and Tertiary Science Education

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    Pre-service teachers come to teacher education programs with a range of experiences and understandings about inquiry in Science. The iScience project aims to assist pre-service teachers develop their understanding of the issues and skills required to guide students through an open inquiry process. In addition, the project provides opportunities for pre-service teachers at the beginning of their teacher training to develop their skills in mentoring high school science students in an open-ended inquiry process. Wikis were used to support the interactions among the pre-service teachers and school students from several different geographical locations to enable collaboration on an open inquiry project. The impact of the project on the pre-service teachers’ understanding of how to teach science by inquiry will be discussed

    Probing the progenitors of Type Ia supernovae using circumstellar material interaction signatures

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    This work aims to study different probes of Type Ia supernova (SN Ia) progenitors that have been suggested to be linked to the presence of circumstellar material (CSM). In particular, we have investigated, for the first time, the link between narrow blueshifted Na i D absorption profiles and the presence and strength of the broad high-velocity Ca ii near-infrared triplet absorption features seen in SNe Ia around maximum light. With the probes exploring different distances from the SN; Na i D > 1017cm, high-velocity Ca ii features < 1015cm. For this, we have used a new intermediate-resolution X-shooter spectral sample of 15 SNe Ia. We do not identify a link between these two probes, implying either that, one (or both) is not physically related to the presence of CSM or that the occurrence of CSM at the distance explored by one probe is not linked to its presence at the distance probed by the other. However, the previously identified statistical excess in the presence of blueshifted (over redshifted) Na i D absorption is confirmed in this sample at high significance and is found to be stronger in SNe Ia hosted by late-type galaxies. This excess is difficult to explain as being from an interstellar-medium origin as has been suggested by some recent modelling, as such an origin is not expected to show a bias for blueshifted absorption. However, a circumstellar origin for these features also appears unsatisfactory based on our new results, given the lack of link between the two probes of CSM investigated

    The Major Histocompatibility Complex–related Fc Receptor for IgG (FcRn) Binds Albumin and Prolongs Its Lifespan

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    The inverse relationship between serum albumin concentration and its half-life suggested to early workers that albumin would be protected from a catabolic fate by a receptor-mediated mechanism much like that proposed for IgG. We show here that albumin binds FcRn in a pH dependent fashion, that the lifespan of albumin is shortened in FcRn-deficient mice, and that the plasma albumin concentration of FcRn-deficient mice is less than half that of wild-type mice. These results affirm the hypothesis that the major histocompatibility complex–related Fc receptor protects albumin from degradation just as it does IgG, prolonging the half-lives of both
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