4,701 research outputs found
The thermo-mechanical performance of glass-fibre reinforced Polyamide 66 during glycol-water hydrolysis conditioning
Injection moulded glass-fibre reinforced polyamide 66 composites based on two glass fibre products with different sizing formulations and unreinforced polymer samples have been characterised by dynamic mechanical analysis and unnotched Charpy impact testing both dry as moulded and during conditioning in a glycol-water mixture at 70°C for a range of times up to 400 hours. Simultaneously weight and dimension changes of these materials have been recorded. The results reveal that hydrothermal ageing in glycol-water mixtures causes significant changes in the thermo-mechanical performance of these materials. It is shown that mechanical performance obtained after conditioning at different temperatures can be superimposed when considered as a function of the level of fluid absorbed by the composite polymer matrix
Characterisation of the transverse thermoelastic properties of natural fibres used in composites
To predict the properties of a composite, it is necessary to identify the properties of the constituent materials, especially those of the fibre. Mechanical properties of natural fibres (NF) are anisotropic and cannot be characterised in the same way as isotropic materials. Therefore further characterisation of the natural fibres is needed to determine their transverse thermo-mechanical behaviour. An understanding of the thermoelastic anisotropy of natural fibres is important for defining their performance in potential composite applications. In this study, thermoelastic properties of flax and sisal fibres where determined through a combination of experimental measurements and micromechanical modelling. Dynamic mechanical thermal analysis and thermal mechanical analysis techniques were employed to characterise model unidirectional NF-epoxy composites over a range off-axis loading angles. These results were input into a number of micromechanical and semi-empirical models to determine the transverse and longitudinal thermoelastic properties of the fibre. The results confirm the high degree of anisotropy in properties of the flax and sisal fibres
Unitarity Restoration in the Presence of Closed Timelike Curves
A proposal is made for a mathematically unambiguous treatment of evolution in
the presence of closed timelike curves. In constrast to other proposals for
handling the naively nonunitary evolution that is often present in such
situations, this proposal is causal, linear in the initial density matrix and
preserves probability. It provides a physically reasonable interpretation of
invertible nonunitary evolution by redefining the final Hilbert space so that
the evolution is unitary or equivalently by removing the nonunitary part of the
evolution operator using a polar decomposition.Comment: LaTeX, 17pp, Revisions: Title change, expanded and clarified
presentation of original proposal, esp. with regard to Heisenberg picture and
remaining in original Hilbert spac
Duchenne Muscular Dystrophy and Brain Function
Muscular dystrophies have historically been characterised according to clinical criteria, however in the genomic age the muscular dystrophies are now subdivided into groups according to the primary gene defect. Currently identified are 29 different loci and encoded proteins, giving rise to 34 distinct forms of muscular dystrophy (Dalkilic & Kunkel 2003;Hsu 2004). The majority of these types of muscular dystrophy are caused by perturbations of different components of the dystrophin-glycoprotein complex (DGC) an integral component of the cellular cytoskeleton (see below). Dystrophin is the largest component of the DGC and is absent in Duchenne muscular dystrophy (DMD), and severely truncated with decreased levels in Becker muscular dystrophy (BMD) (Hoffman & Kunkel 1989). DMD and the allelic BMD are the most common forms of muscular dystrophy in humans and together they are termed dystrophinopathies (Kingston et al. 1984; Shaw & Dreifuss1969). DMD alone accounts for approximately 80% of all the myopathies in the muscular dystrophy group (Culligan et al. 1998).The dystrophin gene is the second largest described to date, totalling 1.5% of the X chromosome, 0.1% of the entire genome. The DMD gene is 99% introns, with a coding sequence of 86 exons (including the promoters) and remains the only known human metagene (Blake et al. 2002; Burmeister et al. 1988; Hamed & Hoffmann 2006; Kenwrick et al. 1987; Koenig et al. 1987; Kunkel et al. 1986; Muntoni et al. 2003; Roberts et al. 1993; Smith et al. 2006; Van Ommen et al. 1987; Wallis et al. 2004). Dystrophin wasdemonstrated to be localised at the sarcolemma in human skeletal muscle after its’ genetic characterisation (Arahata et al. 1988; Sugita et al. 1988; Zubrzycka-Gaarn et al. 1988). This discovery was followed by a report of dystrophin messenger RNA in brain, with the protein being specifically localised at postsynaptic densities (PSD) in the CNS, in particular in the hippocampus, cerebral cortex and in cerebellar Purkinje cells (PC) (Chamberlain et al. 1988; Chelly et al. 1988, 1989; Lidov et al. 1990, Nudel et al. 1988)
Clinical Utility of the MMPI-2-RF Hierarchical Description:An Illustration in Cluster C Personality Disorder Patients
Several studies have addressed the associations between the Minnesota Multiphasic Personality Inventory-2 Restructured form (MMPI-2-RF; Ben-Porath & Tellegen, 2008) scale scores and the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association, 2013) Section II personality disorder (PD) criterion counts. While these studies showed which variables were associated with the PDs as well as their combined predictive potency, no information is available on mean patterns of elevation associated with these conditions. To illustrate how the MMPI-2-RF information may amplify categorical diagnostic information, we describe the mean RF profiles of a psychiatric sample with a Cluster C PD diagnosis. PD classification was based on the Structured Clinical Interview for the DSM-IV (SCID-II). Patterns of elevation across the three levels of the MMPI-2-RF scale sets were consistently in line with theoretical expectation. In addition, elevated scores on somatic/cognitive scales were noted. It is concluded that the MMPI-2-RF can enhance DSM Personality disorder model description.</p
Performance of early weaned calves fed lasalocid
Twenty-two newborn, bull calves were used to determine the effects of
lasalocid on growth and feed intake of early-weaned calves from week 1 to 12.
Calves were assigned to lasalocid or control groups on day 3. Lasalocid-fed group
received lasalocid in milk from day 4 to 7 and in milk and pre-starter from days 7
to 14 and in starter feed from weeks 2 to 12. Lasalocid-fed calves had a
significantly higher feed consumption and greater weight gain than calves that did
not receive lasalocid. The difference became apparent only after 6 wk of age.
Lasalocid appears to be a beneficial feed additive for newborn calves
Centennial-scale vegetation and North Atlantic Oscillation changes during the Late Holocene in the southern Iberia
High-reso CE to lution pollen analysis, charcoal, non-pollen palynomorphs and magnetic susceptibility have been analyzed in the sediment record of a peat bog in Sierra Nevada in southern Iberia. The study of these proxies provided the reconstruction of vegetation, climate, fire and human activity of the last ∼4500 cal yr BP. A progressive trend towards aridification during the late Holocene is observed in this record. This trend is interrupted by millennial- and centennial-scale variability of relatively more humid and arid periods. Arid conditions are recorded between ∼4000 and 3100 cal yr BP, being characterized by a decline in arboreal pollen and with a spike in magnetic susceptibility. This is followed by a relatively humid period from ∼3100 to 1600 cal yr BP, coinciding partially with the Iberian-Roman Humid Period, and is indicated by the increase of Pinus and the decrease in xerophytic taxa. The last 1500 cal yr BP are characterized by several centennial-scale climatic oscillations. Generally arid conditions from ∼450 to 1300 CE, depicted by a decrease in Pinus and an increase in Artemisia, comprise the Dark Ages and the Medieval Climate Anomaly. Since ∼ 1300 to 1850 CE pronounced oscillations occur between relatively humid and arid conditions. Four periods depicted by relatively higher Pinus coinciding with the beginning and end of the Little Ice Age are interrupted by three arid events characterized by an increase in Artemisia. These alternating arid and humid shifts could be explained by centennial-scale changes in the North Atlantic Oscillation and solar activity
An Ensemble Kalman-Particle Predictor-Corrector Filter for Non-Gaussian Data Assimilation
An Ensemble Kalman Filter (EnKF, the predictor) is used make a large change
in the state, followed by a Particle Filer (PF, the corrector) which assigns
importance weights to describe non-Gaussian distribution. The weights are
obtained by nonparametric density estimation. It is demonstrated on several
numerical examples that the new predictor-corrector filter combines the
advantages of the EnKF and the PF and that it is suitable for high dimensional
states which are discretizations of solutions of partial differential
equations.Comment: ICCS 2009, to appear; 9 pages; minor edit
Effect of ruminal protozoa on performance of early-weaned calves
Twenty newborn bull calves assigned to two groups, protozoa-free or protozoa-inoculated, were used to determine the effects of ruminal protozoa on performance of early weaned calves. Calves in the protozoa group were inoculated via stomach tube with a suspension of ruminal protozoa at weekly intervals until a viable population was established. Calves were evaluated weekly for weight gain and feed intake. Feed intake and weight gain were not significantly different between the groups but tended to be higher in protozoa-inoculated than protozoa-free calves.; Dairy Day, 1987, Kansas State University, Manhattan, KS, 1987
Performance of early weaned calves fed lasalocid
Twenty-two newborn, bull calves were used to determine the effects of lasalocid on growth and feed intake of early-weaned calves from week 1 to 12. Calves were assigned to lasalocid or control groups on day 3. Lasalocid-fed group received lasalocid in milk from day 4 to 7 and in milk and pre-starter from days 7 to 14 and in starter feed from weeks 2 to 12. Lasalocid-fed calves had a significantly higher feed consumption and greater weight gain than calves that did not receive lasalocid. The difference became apparent only after 6 wk of age. Lasalocid appears to be a beneficial feed additive for newborn calves.; Dairy Day, 1987, Kansas State University, Manhattan, KS, 1987
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