2,026 research outputs found
Radio-satelllite telemetry of a territorial bearded vulture Gypaetus barbatus in the Caucasus
No Abstract. Vulture News Vol. 56 () 2007: pp. 4-1
Micro and macro approaches to tough polymers for composites
The progress to date on the development of techniques to toughen continuous thermoplastic composites is summarized. The work, using the approach of toughening the polycarbonate composite matrix with rubber particles, has focused on determining the differences between Double Cantilever Beam (DCB) samples molded inhouse and those molded by NASA. Specifically, an effort was made to account for the differences in fracture toughness observed between the various specimens. In addition, preliminary results of tensile dilatometry tests are described; these tests suggest that processes leading to increased volume and enhanced shear banding are occurring within the rubber toughened system. The results of the effort using another approach, the preparation of random block copolycarbonates, are presented. The synthetic route to these species was modified so that higher molecular weights of these materials can be obtained. In addition, an attempt is being made to determine the exact block length or the number of functional groups in the oligomers since this procedure also should lead to high molecular weight materials. Dynamic mechanical analysis of the copolymer prepared so far indicates that the scale of cooperative molecular motion of the PBA polycarbonate at sub-Tg temperatures is larger than five monomer units. Efforts to find a suitable rubber-toughener for a thermoset system (bismaleimides) is also discussed. Included is a description of the various tougheners intended for use or currently being used
Marital Status and Religious Commitment Predict Prenatal Tobacco, Alcohol, and Illicit Substance Use in Southern Appalachia
Abstract available through the Annals of Behavioral Medicine
Religious Commitment and Depression During Pregnancy
Abstract available through the Annals of Behavioral Medicine
Sampling Local Fungal Diversity in an Undergraduate Laboratory using DNA Barcoding
Traditional methods for fungal species identification require diagnostic morphological characters and are often limited by the availability of fresh fruiting bodies and local identification resources. DNA barcoding offers an additional method of species identification and is rapidly developing as a critical tool in fungal taxonomy. As an exercise in an undergraduate biology course, we identified 9 specimens collected from the Hendrix College campus in Conway, Arkansas, USA to the genus or species level using morphology. We report that DNA barcoding targeting the internal transcribed spacer (ITS) region supported several of our taxonomic determinations and we were able to contribute 5 ITS sequences to GenBank that were supported by vouchered collection information. We suggest that small-scale barcoding projects are possible and that they have value for documenting fungal diversity
High intensity exercise decreases IP6K1 muscle content & improves insulin sensitivity in glucose intolerant individuals
Context
Insulin resistance in skeletal muscle contributes to whole body hyperglycaemia and the secondary complications associated with type 2 diabetes. Inositol hexakisphosphate kinase-1 (IP6K1) may inhibit insulin-stimulated glucose transport in this tissue type.
Objective
Muscle and plasma IP6K1 were correlated with two-compartment models of glucose control in insulin-resistant hyperinsulimic individuals. Muscle IP6K1 was also compared following two different exercise trials.
Methods
Nine pre-diabetic [HbA1c; 6.1 (0.2) %)] were recruited to take part in a resting control, a continuous exercise (90% of lactate threshold) and a high-intensity exercise trial (6 x 30 sec sprints). Muscle biopsies were drawn pre- and post each 60-minute trial. A labeled ([6,62H2]glucose) intravenous glucose tolerance test (IVGTT) was performed immediately after the second muscle sample.
Results
Fasting muscle IP6K1 content did not correlate with SI2* (P = 0.961). High-intensity exercise reduced IP6K1 muscle protein and mRNA expression (P = 0.001). There was no effect on protein IP6K1 content following continuous exercise. Akt308 phosphorylation of was significantly greater following high-intensity exercise. Intermittent exercise reduced hepatic glucose production (HGP) following the same trial. The same intervention also improved SI2* and this was significantly greater compared to the continuous exercise improvements. Our in vitro experiment demonstrated that the chemical inhibition of IP6K1 increased insulin signaling in C2C12 myotubes.
Conclusions
The in vivo and in vitro approaches used in the current study suggest that a decrease in muscle IP6K1 may be linked to whole body improvements in SI2*. In addition, high-intensity exercise reduces HPG in insulin-resistant individuals
Evolution of Vibrational Spectra in the Manganese-Silicon Clusters Mn<sub>2</sub>Si<sub>n</sub>, n = 10, 12, and 13, and Cationic [Mn<sub>2</sub>Si<sub>13</sub>]<sup>+</sup>
A comparison of DFT-computed and measured infrared spectra reveals the ground state structures of a series of gas-phase silicon clusters containing a common Mn2 unit. Mn2Si12 and [Mn2Si13]+ are both axially symmetric, allowing for a clean separation of the vibrational modes into parallel (a1) and perpendicular (e1) components. Information about the Mn–Mn and Mn–Si bonding can be extracted by tracing the evolution of these modes as the cluster increases in size. In [Mn2Si13]+ where the antiprismatic core is capped on both hexagonal faces, a relatively simple spectrum emerges that reflects a pseudo-D6d geometry. In cases where the cluster is more polar, either because there is no capping atom in the lower face (Mn2Si12) or the capping atom is present but displaced off the principal axis (Mn2Si13), the spectra include additional features derived from vibrational modes that are forbidden in the parent antiprism
Dental fluorosis in populations from Chiang Mai, Thailand with different fluoride exposures - Paper 2: The ability of fluorescence imaging to detect differences in fluorosis prevalence and severity for different fluoride intakes from water
BACKGROUND: To assess the ability of fluorescence imaging to detect a dose response relationship between fluorosis severity and different levels of fluoride in water supplies compared to remote photographic scoring in selected populations participating in an observational, epidemiological survey in Chiang Mai, Thailand. METHODS: Subjects were male and female lifetime residents aged 8-13 years. For each child the fluoride content of cooking water samples (CWS) was assessed to create categorical intervals of water fluoride concentration. Fluorescence images were taken of the maxillary central incisors and analyzed for dental fluorosis using two different software techniques. Output metrics for the fluorescence imaging techniques were compared to TF scores from blinded photographic scores obtained from the survey. RESULTS: Data from 553 subjects were available. Both software analysis techniques demonstrated significant correlations with the photographic scores. The metrics for area effected by fluorosis and the overall fluorescence loss had the strongest association with the photographic TF score (Spearman’s rho 0.664 and 0.652 respectively). Both software techniques performed well for comparison of repeat fluorescence images with ICC values of 0.95 and 0.85 respectively. CONCLUSIONS: This study supports the potential use of fluorescence imaging for the objective quantification of dental fluorosis. Fluorescence imaging was able to discriminate between populations with different fluoride exposures on a comparable level to remote photographic scoring with acceptable levels of repeatability
Scaling in Plasticity-Induced Cell-Boundary Microstructure: Fragmentation and Rotational Diffusion
We develop a simple computational model for cell boundary evolution in
plastic deformation. We study the cell boundary size distribution and cell
boundary misorientation distribution that experimentally have been found to
have scaling forms that are largely material independent. The cell division
acts as a source term in the misorientation distribution which significantly
alters the scaling form, giving it a linear slope at small misorientation
angles as observed in the experiments. We compare the results of our simulation
to two closely related exactly solvable models which exhibit scaling behavior
at late times: (i) fragmentation theory and (ii) a random walk in rotation
space with a source term. We find that the scaling exponents in our simulation
agree with those of the theories, and that the scaling collapses obey the same
equations, but that the shape of the scaling functions depend upon the methods
used to measure sizes and to weight averages and histograms
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