To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We investigate the contribution of a local over- or under-density to linear estimates of the cosmic dipole. We focus on radio continuum surveys. Recently it was shown that the radio dipole amplitude is larger than expected from the corresponding dipole of the CMB. We show that a significant contribution to this excess could come from local structure.
We examined the light variations of AGB variables of the two Local Group members NGC 147 and NGC 185. A photometric monitoring in the i-band was carried out with the Nordic Optical Telescope at La Palma over ≈ 2.5 yrs resulting in roughly 35 data points for the period analysis. We found 513 long period variables (LPVs) in NGC 185 and 213 LPVs in NGC 147. Additional single-epoch Ks-band photometry was obtained for 387 (NGC 185, 323 with periods) and 182 (NGC 147, 147 with periods) LPVs, respectively. For a large fraction of these stars we also have an indication of the atmospheric chemistry (carbon- or oxygen-rich) from narrow band photometry (see Nowotny et al. 2003). The resulting Ks − logP diagrams for both systems show a well populated sequence of fundamental mode pulsators (sequence C, cf. Ita et al. 2004). In NGC 185 we also see a number of LPVs pulsating in the first overtone mode (sequence C’). Interestingly, such stars are missing in NGC 147. We speculate that this lack of shorter period variables in NGC 147 could originate from a difference in the star formation history (SFH) of the two galaxies, with NGC 147 containing a smaller population of intermediate-age stars.
We report on a measles outbreak originating in an anthroposophic community in Austria, 2008. A total of 394 (94·9%) cases fulfilled the outbreak case definition including 168 cases affiliated to the anthroposophic community. The source case was a school pupil from Switzerland. The Austrian outbreak strain was genotype D5, indistinguishable from the Swiss outbreak strain. A school-based retrospective cohort study in the anthroposophic school demonstrated a vaccine effectiveness of 97·3% in pupils who had received a single dose of measles-containing vaccine and 100% in those who had received two doses. The vaccination coverage of the cases in the anthroposophic community was 0·6%. Of the 226 outbreak cases not belonging to the anthroposophic community, the 10–24 years age group was the most affected. Our findings underline the epidemiological significance of suboptimal vaccination coverage in anthroposophic communities and in older age groups of the general population in facilitating measles virus circulation. The findings of this outbreak investigation suggest that the WHO European Region is unlikely to achieve its 2010 target for measles and rubella elimination.
Questions remain about the long-term health impacts of the 1991 Gulf War on its veterans.
To measure psychological disorders in Australian Gulf War veterans and a military comparison group and to explore any association with exposure to Gulf War-related psychological stressors.
Prevalences of DSM–IV psychological disorders were measured using the Composite International Diagnostic Interview. Gulf War-related psychological stressors were measured using a service experience questionnaire.
A total of 31% of male Gulf War veterans and 21% of the comparison group met criteria for a DSM–IVdisorder first present in the post-Gulf War period. The veterans were at greater risk of developing post-Gulf War anxiety disorders including post-traumatic stress disorder, affective disorders and substance use disorders. The prevalence of such disorders remained elevated a decade after deployment. The findings can be explained partly as a ‘war-deployment effect‘. There was a strong dose–response relationship between psychological disorders and number of reported Gulf War-related psychological stressors.
Service in the 1991 Gulf War is associated with increased risk of psychological disorders and these are related to stressful experiences.
We studied activity patterns and habitat use by insectivorous bats in Comoé National Park, Ivory Coast. Bat foraging activity was quantified along five transects representing three different habitat types using acoustic monitoring and captures with mist nets and harp traps. Aerial insect abundance was assessed using a light trap; in addition shrub and tree arthropods were sampled. Bat activity was significantly and positively related to insect availability and ambient temperature, whereas increased visibility of the moon had a negative influence on flight activity. Together, these factors best explained both total bat activity and activity of bats hunting in open space and edge habitats. The interaction between temperature and light intensity was the best predictor of activity by species foraging in obstacle-rich forest habitats, however, the regression model had a low predictive value. Overall, a large proportion (c. 50%) of the variation in bat activity appeared to be a consequence of transect- and/or habitat-specific influences. We found a significant non-linear relationship between the activity of QCF (quasi-constant frequency) and FM–QCF (frequency modulated – quasi-constant frequency) bats and the phase of the moon, with lowest levels of activity occurring near full moon. We interpret this lunar-phobic behaviour as a reflection of a higher predation risk during moonlit periods. For FM (steep frequency modulated) and CF (constant frequency) bats, no significant correlation was found, although there was a trend suggesting that these bats at least were not negatively affected by bright moonlight. Foraging activity of bats was positively correlated with the abundance of atympanate moths; however, no such correlation was found for tympanate moths.
Multiwavelength observations of polars are essential for developing the big picture of these systems, particularly to gain understanding of the relevant accretion-induced heating and cooling processes. Eclipsing polars are prime targets for such studies since different radiation processes can be disentangled by observations with high-time resolution. We present a preliminary combined analysis of space-based observations (XMM-Newton, ROSAT, HST) with ground-based high-speed photometry (MCCP, OPTIMA, ULTRACAM) of DP Leo, HU Aqr and UZ For. We determine the location and extent of different emission components and find secular and short-term changes in the accretion geometries. We find displaced optical and X-ray emission regions in DP Leo and HU Aqr as well as mini-bursts and accretion arcs of variable size in HU Aqr. We report marked changes in the X-ray eclipse length of UZ For between high and low states.
Alluvial rubies and sapphires are found in palaeodrainage deposits along the Cudgegong-Macquarie River system, central eastern New South Wales, Australia. A pink to red suite contains Cr (up to 0.6 wt.% Cr2O3) as the main chromophore, exceeding Fe (up to 0.5 wt.%Fe2O3). Corrosive etching suggests a prior xenocrystic Mesozoic-Cenozoic basaltic transport, while Cr2O3/Ga2O3 to Fe2O3/TiO2 ratios indicate an original metamorphic source. Syngenetic mineral inclusions include Al-rich diopside, meionite and anatase. The Al-rich diopside (‘fassaite’) contains extremely high Al2O3 (20–21 wt.%). A blue-green suite contains Fe (up to 0.8 wt.% Fe2O3) as a dominant chromophore, while a rare nepheline-anorthoclase composite inclusion supports a magmatic phonolitic origin. The Cudgegong- Macquarie ruby formation is compared with a garnet granulite origin proposed for Thailand rubies and a xenolith of corundum-bearing garnet granulite from Ruby Hill, Bingara, Australia. Clinopyroxenecorundum thermometry suggests the Cudgegong-Macquarie rubies formed at T >1000–1300ºC, a high equilibration T for proposed lithospheric granulites. These rubies form a distinctive suite compared to other rubies from Australian and SE Asian basalt fields, but have some similarities with eastern Thailand rubies.
This paper briefly describes the principle of operation and science goals of the AMANDA high energy neutrino telescope located at the South Pole, Antarctica. Results from an earlier phase of the telescope, called AMANDA-BIO, demonstrate both reliable operation and the broad astrophysical reach of this device, which includes searches for a variety of sources of ultrahigh energy neutrinos: generic point sources, Gamma-Ray Bursts and diffuse sources. The predicted sensitivity and angular resolution of the telescope were confirmed by studies of atmospheric muon and neutrino backgrounds. We also report on the status of the analysis from AMANDA-II, a larger version with far greater capabilities. At this stage of analysis, details of the ice properties and other systematic uncertainties of the AMANDA-II telescope are under study, but we have made progress toward critical science objectives. In particular, we present the first preliminary flux limits from AMANDA-II on the search for continuous emission from astrophysical point sources, and report on the search for correlated neutrino emission from Gamma Ray Bursts detected by BATSE before decommissioning in May 2000. During the next two years, we expect to exploit the full potential of AMANDA-II with the installation of a new data acquisition system that records full waveforms from the in-ice optical sensors.
Using molecular dynamics and a modified embedded atom potential developed by our group we studied the diffusivity and viscosity of molten Ni1-xZrx alloys as a function of composition, temperature, and cooling rate. Previous results indicate that these potentials represent the Ni-Zr system quite well. Liquid alloys were quenched at rates of 5 × 1011 and 1012 K/s. For x > 0.04 the solidified alloys were crystalline. For higher x values, the solidified alloys were amorphous. For the amorphous alloys, the composition dependence of the calculated glass transition temperature Tg follows the general trend of experimental Tg values. The calculated viscosity and diffusivity show systematic variation with composition. For the undercooled Ni-6 at.% Zr melt the calculated viscosity shows the Vogel-Fulcher-Tammann (VFT) behavior characteristic of a “fragile” glass.
Buried dislocation superlattices are obtained by bonding ultra-thin single crystal Si (001) films on Si (001) wafers. The twist of two Si wafers induces a regular square grid of dissociated screw dislocations and the tilt a 1-D array of mixed dislocation. The Burgers vector is a/2 <110> for both types of dislocation. The atomic displacements and deformations of pure screw and edge dislocations are calculated with an isotropic elasticity approximation taking into account the free surface and the thickness of the upper crystal. It is shown by these calculations that the elastic strain field propagates up to the surface, and quantitative arguments are given to choose the network period / film thickness ratio.
Discrete and coalesced monocrystalline GaN and AlxGa1−xN layers grown via pendeo-epitaxy (PE) originated from side walls of GaN seed stripes with and without SiNx top masks have been grown via organometallic vapor phase deposition on GaN/AlN/6H-SiC(0001) and GaN(0001)/AlN(0001)/3C-SiC(111)/Si(111) substrates. Scanning and transmission electron microscopies were used to evaluate the external microstructures and the distribution of dislocations, respectively. The dislocation density in the laterally grown sidewall regions and in the regions grown over the SiNx masks was reduced by at least five orders of magnitude relative to the initial GaN seed layers. Tilting of 0.2° in the coalesced GaN epilayers grown over the SiNx masks was determined via X-ray and selected area diffraction; however, tilting was not observed in the material suspended above the SiC substrate and that grown on unmasked stripes. A strong, low-temperature photoluminescence band-edge peak at ~3.45 eV with a FWHM of <300 µeV was determined on the overgrowth material grown on the silicon carbide substrates. The band-edge in the GaN grown on silicon substrates was shifted to a lower energy by 10 meV, indicative of a greater tensile stress.
This investigation was designed to estimate the Co requirement of growing cattle on the basis of plasma and liver levels of vitamin B12 and folate, plasma levels of homocysteine and methylmalonic acid (MMA) and haematological variables. For this purpose thirty-four male intact cattle of the German Simmental breed (236 kg) were assigned randomly to ten groups and were fed corn silage-based diets which contained 70, 90, 109, 147, 184, 257, 327, 421, 589 or 689 μg Co/kg DM for 40 weeks. One-slope broken-line model analysis and a quadratic model with plateau were used to estimate the Co requirement. The broken-line model estimated the dietary Co requirement of growing cattle to be 257 (SE 29) ΜG/KG DIETARY DM BASED ON PLASMA VITAMIN B12 AS RESPONSE CRITERION. THE DIETARY CO LEVELS NEEDED TO MAXIMISE THE LIVER VITAMIN B12 AND LIVER FOLATE WERE 236 (se 8) and 190 (se 8) μg/kg dietary DM respectively. Plasma folate did not show any response to the different Co levels. The dietary Co was inversely correlated with the plasma concentrations of homocysteine and MMA. Estimates of the dietary Co concentration required to minimise homocysteine were 161 (se 10) μg/kg DM. When MMA was used as response criterion, the linear model yielded a Co requirement of 124 (se 3) μg/kg dietary DM. The quadratic model did not provide a better closeness of regression fit and yielded similar requirements to the linear model. Haemoglobin concentration and haematocrit tended to have a slight response to increasing dietary Co and were only decreased in cattle on diets containing less than 100 μg Co/kg DM. On the basis of the present data, recommended levels of dietary Co for normal folate metabolism and minimum homocysteine and MMA levels can be set to be 150–200 μg/kg DM; for maximum vitamin B12 levels, the desired Co content in the diet seems to be 250 μg/kg DM.
In ruminants, Co is required for the synthesis of vitamin B12, which in turn is needed for the resynthesis of methionine by methylation of homocysteine and thus, cobalamin deficiency may induce hyperhomocysteinaemia which is brought into context with perturbations of the antioxidative–prooxidative balance. The present study was conducted to explore whether Co deficiency in cattle is also associated with homocysteine-induced disturbances of oxidative status. Co deficiency was induced in cattle by feeding two groups of animals on either a basal maize-silage-based diet that was moderately low in Co (83 μg Co/kg DM), or the same diet supplemented with Co to a total of 200 μg Co/kg DM, for 43 weeks. Co deficiency was apparent from a reduced vitamin B12 status in serum and liver and an accumulation of homocysteine in plasma which was in excess of 4·8 times higher in Co-deprived cattle than in controls. The much increased level of circulating homocysteine did not indicate severe disturbances in antioxidant–prooxidant balance as measured by individual markers of lipid peroxidation, protein oxidation, and the antioxidative defence system. There were no quantitative difference in plasma thiol groups, nor were there significant changes in concentrations of α-tocopherol, microsomal thiobarbituric acid-reactive substances and carbonyl groups in liver. However, there was a trend toward increased plasma carbonyl levels indicating a slight degradation of plasma proteins in the hyperhomocysteinaemic cattle. Analysis of the hepatic catalase (EC 188.8.131.52) activity revealed an 11 % reduction in Co-deficient cattle relative to the controls. These results indicate that long-term moderate Co deficiency may induce a severe accumulation of plasma homocysteine in cattle, but considerable abnormalities in oxidative status failed to appear.
Nature and origin of the high-velocity clouds (HVCs) remain enigmatic after thirty years (Wakker & van Woerden 1997, ARA&A, 35, 217), owing to lack of distance information. Hypotheses range from supernova shells at 100 pc to intergalactic clouds at 1 Mpc. On statistical grounds, Blitz et al. (1996, BAAS, 28, 1349) claim that the HVCs are “remnants of Local Group formation, best explained as members of the Local Group of galaxies”. Reliable distances must come from the presence or absence of absorption at the HVC's velocity in spectra of stars at different distances. For Complex A, MgII absorption is seen in HST spectra of the Seyfert galaxy Mrk 106, but not in the star PG0859+593 at 4 kpc (Wakker et al. 1996, ApJ, 473, 834). La Palma spectra of the RR Lyr star AD UMa at 11 kpc distance show CaII absorption by Complex A at both K and H, which is lacking at 4 kpc. These absorptions are not confused with stellar metal lines. Our distance bracket 4 < d < 11 kpc places Complex A in the Galactic Halo, at 2.5 < z < 7.5 kpc above the plane; a distance similar to Local Group galaxies is excluded. The HI mass implied lies between 0.15 and 1.2 times 106M⊙. Our result precludes local origins for this HVC. It allows an origin in a Galactic Fountain, or in interaction of infalling intergalactic material (from the Magellanic System or the Local Group) with the Galactic Halo.
We report on electroabsorption spectra for plasma deposited thin films of hydrogenated silicon ranging from amorphous (a-Si:H) to microcrystalline (μc-Si-H) structures. The EA spectrum of a-Si:H deposited from silane with low hydrogen dilution were consistent with previous works; material prepared with high hydrogen dilution showed a 0.07 eV blue shift of the spectrum and somewhat stronger electroabsorption. μc-Si-H specimens have a sharp peak at 1.19eV; the spectrum is blue shifted by 0.03 eV and is significantly stronger than electroabsorption reported in single crystal silicon. Spectral features which have no correspondence to single crystal silicon were also observed in μc-Si-H. Specimens deposited using “cyclic” deposition and chemical annealing had electroabsorption spectra with both the 1.19 eV, crystalline feature and a band peaking at 2.02 eV which we attribute to strongly hydrogenated a-Si:H. We discuss applications of electroabsorption to determining the crystal fraction of microcrystalline material and to determining grain size distributions.
We present firm evidence that one of the major high velocity clouds (HVCs), Complex A, lies in the Milky Way Halo, at a vertical distance z = 3 - 7 kpc from the Galactic plane. For clouds MII/MIII, Danly et al. and Keenan et al. had already found z < 5 kpc. We further report that the metallicity in the largest HVC, Complex C, is at least 0.1 solar. Call/Hi ratios in 6 HVCs, ranging from 0.002 to 0.07 times solar, set lower limits to their metallicities.
Blitz et al. have recently suggested that most of the HVCs are relatively unprocessed, extragalactic remnants of the gas which formed the Local Group of galaxies. However, the results mentioned above indicate that several major HVC complexes are neither primordial nor extragalactic. For the smaller HVCs, some of which have much higher velocities, a location in the Local Group remains a possibility.
Concentrations of growth hormone (GH), insulin-like growth factor (IGF-1), insulin and glucagon were determined in the plasma of growing bulls, steers and heifers (no. = 138 in total, German Simmental breed). The animals were offered either a high level or a low level of energy resulting in relatively high and low average daily gain. Trials were subdivided into two experimental series and started at approximately 3 months of age at an average live weight of 110 kg. The animals were slaughtered at different body weights from 200 to 510 kg (heifers) or 660 kg (bulls, steers). Blood samples (needle puncture) were collected at biweekly intervals. Frequent samples time-course analysis of GH were taken by catheter from nine animals in total. Concentrations of GH declined during growth in steers and heifers as well as in bulls in blood samples collected by means of a catheter. IGF-1 and insulin concentrations increased from the start of the trial onwards up to different ages among the groups. Concentrations of glucagon constantly decreased from the start of the trial until slaughter. Significant differences (P < 0·05) in concentrations ofGH, IGF-1 and insulin could be observed between sexes and levels of nutrition, with the highest GH and IGF-1 levels in bulls followed by steers and heifers. In contrast insulin values were highest in heifers followed by steers and bulls. A high level of nutrition increased concentrations of IGF-1 and insulin in all sexes.
Microstructural differences in copper deposited by four techniques commonly used in the microelectronics industry were previously reported.  The reaction rates were predicted using either grain size or grain orientation as the dominant microstructure characteristic. A practical method to monitor copper speciation was developed. This technique was used to measure the reaction rates for the different copper films under two different etching conditions. The results are explained using grain size, grain orientation and near surface region composition.
Hydrogenated amorphous silicon, a-Si:H, is deposited from silane (SiH4) and hydrogen (H2) using a tungsten wire at low filament temperatures (Tfil = 1200°C) by catalytic chemical vapor deposition.
The deposition rate increases monotonically with the depositions pressures and shows a maximum at an H2 : SiH4 flow ratio of unity. Vanishingly small deposition rates were observed for silane-only depositions and for H2-to-SiH4 flow ratios of 2.5 and above. The optoelectronic properties show complex dependence on substrate temperature (Tsub). Three intervals of Tsub with distinct optoelectronic were observed: as Tsub increases from 180 to 220°C, the optical bandgap, EgTauc increases from 1.9 to 2.4eV, the dark conductivity,σd, decreases from 10-10 to 10-15 Ω-1cm-1and the photoconductivity, σph, decreases from 10-5 to 10-10Ω-1cm-1 (region (i)). As Tsub increases from 220 to 250 °C, EgTauc decreases to 1.8eV and the photosensitivity, σph/σd decreases to ~ 1 due to an increase of both σd and σph (region (ii)). Throughout these two regions, the photoconductivity γ factor remains between 0.6 and 0.9 and the activation energy of the dark conductivity, Ea,σd, remains between 0.7 and 0.9eV. Above 250°C, the σph and σd remain approximately constant at 10-4 Ω-1cm-1 and γ decreases to below 0.5 and Ea,σd ~ 0.3eV.