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The role that vitamin D plays in pulmonary function remains uncertain. Epidemiological studies reported mixed findings for serum 25-hydroxyvitamin D (25(OH)D)–pulmonary function association. We conducted the largest cross-sectional meta-analysis of the 25(OH)D–pulmonary function association to date, based on nine European ancestry (EA) cohorts (n 22 838) and five African ancestry (AA) cohorts (n 4290) in the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium. Data were analysed using linear models by cohort and ancestry. Effect modification by smoking status (current/former/never) was tested. Results were combined using fixed-effects meta-analysis. Mean serum 25(OH)D was 68 (sd 29) nmol/l for EA and 49 (sd 21) nmol/l for AA. For each 1 nmol/l higher 25(OH)D, forced expiratory volume in the 1st second (FEV1) was higher by 1·1 ml in EA (95 % CI 0·9, 1·3; P<0·0001) and 1·8 ml (95 % CI 1·1, 2·5; P<0·0001) in AA (Prace difference=0·06), and forced vital capacity (FVC) was higher by 1·3 ml in EA (95 % CI 1·0, 1·6; P<0·0001) and 1·5 ml (95 % CI 0·8, 2·3; P=0·0001) in AA (Prace difference=0·56). Among EA, the 25(OH)D–FVC association was stronger in smokers: per 1 nmol/l higher 25(OH)D, FVC was higher by 1·7 ml (95 % CI 1·1, 2·3) for current smokers and 1·7 ml (95 % CI 1·2, 2·1) for former smokers, compared with 0·8 ml (95 % CI 0·4, 1·2) for never smokers. In summary, the 25(OH)D associations with FEV1 and FVC were positive in both ancestries. In EA, a stronger association was observed for smokers compared with never smokers, which supports the importance of vitamin D in vulnerable populations.
It has been suggested that cattle have a greater ability to digest fibrous feeds and a lower ability to digest non-fibrous feeds than sheep (Mc Donald et al., 1995). This statement applies mainly to forages and few direct comparisons have been conducted using concentrate ingredients. The digestibility of concentrate ingredients may be influenced by the level of consumption since an increase in intake of a complete diet resulted in a decrease in digestibility (El Khidir and Vestergaard Thomsen, 1983). The aims of this study were (a) to determine the effect of level of consumption by cattle and (b) to examine the effect of animal species (sheep and cattle) on the digestibility of concentrate ingredients.
Empirical models relate nutrient inputs and outputs statistically, without considering the intervening metabolism of the animal (France and Thornley, 1984). Current rationing systems (e.g. ARC, 1980; Jarrige, 1988) are based on empirical models of energy and protein utilisation within the animal and do not enable prediction of responses to changes in nutrient inputs (Beever et al., 1991). Rook et al. (1990) had limited success in attempting to develop empirical regression models to describe the effect of nutrient input on milk constituent yields in dairy cows. The aim of the current study was therefore to use data from the literature to develop more appropriate empirical models that would allow the prediction of response in milk output and its constituent, to changes in energy intake.
In the majority of farming systems in Ireland and the UK, grass silage is supplemented with varying types and levels of concentrates when offered to lactating dairy cows (Keady et al., 1998). This supplementation results in a reduction in the intake of the silage. The aim of the current study was therefore to use data from the literature to develop empirical models that would allow the prediction of grass silage dry matter intake with increasing amounts of concentrate intake.
Poor reproductive performance is a major problem on dairy farms throughout the United Kingdom, resulting in reduced financial returns for the farmer. As the genetic merit of the cow increases, an increasing proportion of nutrients are partitioned towards milk production and this can result in the cow entering into a more severe negative energy balance (NEB). Previous studies have shown that the extent of NEB may influence the expression of oestrous behaviour (Orihuela, 2000). The aim of the current study was to examine the effect of offering a high or low proportion of concentrate (70% and 40% respectively, with the balance being grass silage) in the total diet, on the expression of oestrous behaviour of high genetic merit Holstein Friesian lactating dairy cows, using optical electronic oestrous detection equipment.
Robust time-averaged molecular dynamics has been developed to calculate finite-temperature elastic constants of a single crystal. We find that when the averaging time exceeds a certain threshold, the statistical errors in the calculated elastic constants become very small. We applied this method to compare the elastic constants of Pd and PdH0.6 at representative low (10 K) and high (500 K) temperatures. The values predicted for Pd match reasonably well with ultrasonic experimental data at both temperatures. In contrast, the predicted elastic constants for PdH0.6 only match well with ultrasonic data at 10 K; whereas, at 500 K, the predicted values are significantly lower. We hypothesize that at 500 K, the facile hydrogen diffusion in PdH0.6 alters the speed of sound, resulting in significantly reduced values of predicted elastic constants as compared to the ultrasonic experimental data. Literature mechanical testing experiments seem to support this hypothesis.
We present the first results from multi-site observations of the δ Scuti star XX Pyx (CD–24°7599). The observations were carried out as the 17th run of the Delta Scuti Network. We collected 583 hr of B, V time-series photometry, resulting in a detection level (4σ) in the amplitude spectrum of 0.5 mmag. We detect 6 new pulsation frequencies, bringing the total number of frequencies known in this star up 19.
The cold, dry, and stable air above the summits of the Antarctic plateau provides the best ground-based observing conditions from optical to sub-millimetre wavelengths to be found on the Earth. Pathfinder for an International Large Optical Telescope (PILOT) is a proposed 2 m telescope, to be built at Dome C in Antarctica, able to exploit these conditions for conducting astronomy at optical and infrared wavelengths. While PILOT is intended as a pathfinder towards the construction of future grand-design facilities, it will also be able to undertake a range of fundamental science investigations in its own right. This paper provides the performance specifications for PILOT, including its instrumentation. It then describes the kinds of projects that it could best conduct. These range from planetary science to the search for other solar systems, from star formation within the Galaxy to the star formation history of the Universe, and from gravitational lensing caused by exo-planets to that produced by the cosmic web of dark matter. PILOT would be particularly powerful for wide-field imaging at infrared wavelengths, achieving near diffraction-limited performance with simple tip–tilt wavefront correction. PILOT would also be capable of near diffraction-limited performance in the optical wavebands, as well be able to open new wavebands for regular ground-based observation, in the mid-IR from 17 to 40 μm and in the sub-millimetre at 200 μm.
The Magellanic System represents one of the best places to study the formation and evolution of galaxies. Photometric surveys of various depths, areas and wavelengths have had a significant impact on our understanding of the system; however, a complete picture is still lacking. VMC (the VISTA near-infrared YJKs survey of the Magellanic System) will provide new data to derive the spatially resolved star formation history and to construct a three-dimensional map of the system. These data combined with those from other ongoing and planned surveys will give us an absolutely unique view of the system opening up the doors to truly new science!
Herpes virus infections can cause cognitive impairment during and after acute encephalitis. Although chronic, latent/persistent infection is considered to be relatively benign, some studies have documented cognitive impairment in exposed persons that is untraceable to encephalitis. These studies were conducted among schizophrenia (SZ) patients or older community dwellers, among whom it is difficult to control for the effects of co-morbid illness and medications. To determine whether the associations can be generalized to other groups, we examined a large sample of younger control individuals, SZ patients and their non-psychotic relatives (n=1852).
Using multivariate models, cognitive performance was evaluated in relation to exposures to herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2) and cytomegalovirus (CMV), controlling for familial and diagnostic status and sociodemographic variables, including occupation and educational status. Composite cognitive measures were derived from nine cognitive domains using principal components of heritability (PCH). Exposure was indexed by antibodies to viral antigens.
PCH1, the most heritable component of cognitive performance, declines with exposure to CMV or HSV-1 regardless of case/relative/control group status (p = 1.09 × 10−5 and 0.01 respectively), with stronger association with exposure to multiple herpes viruses (β = −0.25, p = 7.28 × 10−10). There were no significant interactions between exposure and group status.
Latent/persistent herpes virus infections can be associated with cognitive impairments regardless of other health status.
We report on the growth and quality of plasma enhanced molecular beam epitaxy (PEMBE) of an n-GaN layer grown on a 6H-SiC substrate, which was prepared to be half nanoporous. A layer of nanoporous SiC was fabricated on a half section of n-type, on-axis (0001)Si face 41 mm commercial wafer by surface anodization. Following H-plasma surface cleaning and in-situ thermal annealing, a 0.7µm thick silicon doped GaN film was deposited at a growth rate of 0.35µm/hr. Substrate temperature during GaN growth was 709oC with a chamber pressure of 1.9 × 10−5Torr. Results of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) characterization suggest improved chemical quality of the film grown on the nanoporous section. Photoluminescence (PL) data indicate greatly reduced nonradiative recombination in the epi layer grown on the nanoporous as compared to the control surface.
Among metallic systems, titanium alloys are prime candidate materials for biomedical applications in view of their apparent properties in the body environment. While machined and forged parts of CPTi, or Ti-6Al-4V, are suitable for many applications, they are not economical for one-off objects or artefacts of extreme intricacy. Titanium castings are an obvious solution to the problem but these are extremely difficult to process without contamination. Alloying allows a lowering of the melting point and significantly reduces the risk of contamination but the resultant alloys are normally brittle due to networks of intermetallics forming. This paper describes a process of semi-solid casting using a powder titanium feedstock for making one-off castings of artefacts like those required in dentistry. The process will be described and the mechanical and corrosion properties of several alloys which are compatible with this technique are assessed. The basic process is relatively inexpensive and provides a useful tool for examining a wide range of potential titanium base alloys.
Here we present our recent work on the fabrication of high crystalline and optical quality ZnO films on sapphire (001) by pulsed laser deposition. The influence of deposition parameters such as the substrate temperature, oxygen pressure, laser fluence, and pulse repetition rate on the crystalline quality of ZnO layers has been studied. The Ω-rocking curve FWHM of the (002) peak for the films grown at 750°, oxygen pressure 10−5 Torr was 0.17°. The XRD-Ф scans studies revealed that the films were epitaxial with a 30° rotation of the unit cell with respect to the sapphire to achieve a low energy configuration for epitaxial growth. The high degree of crystallinity was confirmed by ion channeling technique providing a minimum Rutherford backscattering yield of 2–3% in the near surface region (-2000Å). The atomic force microscopy revealed smooth hexagonal faceting of the films. The optical absorption edge measured by UV-Visible spectroscopy was sharp at 383 nm. Excellent crystalline properties of these epi-ZnO/sapphire heterostractures are thus promising for III-V nitride heteroepitaxy.
Using micro-capillaries and capillary arrays, we have fabricated dye- and C60-doped liquid crystal cored fibers and image transmission plates of various core diameters and lengths. We have observed nonlinear pulse propagation and limiting effect using nanosecond 0.53 μm Nd:Yag laser. Typical threshold fluence is on the order of < 1 J/cm2 in a 7 mm long fiber. A theoretical modelling of the observed effect is also presented.
We have grown YBa2Cu3O7 (YBCO) and Pr1.85Ce0.15CuO4 (PCCO) polycrystalline films on n-type GaN using pulsed laser deposition. The diodes fabricated out of these heterostructures exhibited a strong rectifying behavior with transport characteristics that were found to fit well to the thermionic emission model. The effective barrier heights for YBCO and PCCO based diodes were found to be 788 meV and 236 meV, respectively. Rutherford Backscattering structural analysis of the heterostructures is also discussed.