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Detecting gastrointestinal (GI) infection transmission among men who have sex with men (MSM) in England is complicated by a lack of routine sexual behavioural data. We investigated whether gender distributions might generate signals for increased transmission of GI pathogens among MSM. We examined the percentage male of laboratory-confirmed patient-episodes for patients with no known travel history for 10 GI infections of public health interest in England between 2003 and 2013, stratified by age and region. An adult male excess was observed for Shigella spp. (annual maximum 71% male); most pronounced for those aged 25–49 years and living in London, Brighton and Manchester. An adult male excess was observed every year for Entamoeba histolytica (range 59.8–76.1% male), Giardia (53.1–57.6%) and Campylobacter (52.1–53.5%) and for a minority of years for hepatitis A (max. 69.8%) and typhoidal salmonella (max. 65.7%). This approach generated a signal for excess male episodes for six GI pathogens, including a characterised outbreak of Shigella among MSM. Stratified analyses by geography and age group were consistent with MSM transmission for Shigella. Optimisation and routine application of this technique by public health authorities elsewhere might help identify potential GI infection outbreaks due to sexual transmission among MSM, for further investigation.
Current star-forming galaxies (SFGs) with CO measurements at z ~ 2 suffer from a bias toward high star formation rates (SFR) and high stellar masses (M*). It is yet essential to extend the CO measurements to the more numerous z ~ 2 SFGs with LIR < L⋆ = 4× 1011 L⊙ and M* < 2.5× 1010 M⊙. We have achieved CO, stars, and dust measurements in 8 such sub-L⋆ SFGs with the help of gravitational lensing. Combined with CO-detected galaxies from the literature, we find that the LIR, L′CO(1−0) data are best-fitted with a single relation that favours a universal star formation. This picture emerges because of the enlarged star formation efficiency spread of the current z>1 SFGs sample. We show that this spread is mostly triggered by the combination of redshift, specific SFR, and M*. Finally, we find evidence for a non-universal dust-to-gas ratio (DGR) with a clear trend for a lower DGR mean in z>1 SFGs by a factor of 2 with respect to local galaxies and high-redshift sub-mm galaxies at fixed about solar metallicity.
We present an X-ray diffraction study of a semiconductor symmetric tilt grain boundary. The theory of crystal truncation rod scattering is extended to bicrystal interfaces and compared with experimental data measured at the Diamond Light Source.
We present some notes concerning recent achievements in observational
and theoretical cosmology, especially CMB cosmology. We emphasize
that some cosmological processes could be more complicated than the standard
cosmological scenario. In this case we need additional parameters for their
description. Taking into account these new “missing” parameters we
obtain alternative values for the old standard cosmological parameters to provide
the best fit to the observational data. As an example we show that the more
complicated models of the kinetics of recombination (with a few new
“missing” parameters describing the recombination processes at z ≃ 103)
provide better agreement between measured and expected characteristics of
the CMB anisotropy.
The Low Frequency Array is a new radio telescope based on phased array
principles that will operate at frequencies from 10–240 MHz. The vast
improvement in sensitivity and resolution over previous instruments
that have worked at these frequencies, together with the increased
flexibility that results from the phased array approach
(multi-beaming, no moving parts) make LOFAR an extremely versatile and
powerful new instrument. We present some of the scientific drivers and
give an overview of the current design.
The plasma concentrations of cortisol and progesterone during reproductive maturation in the heifer calf were examined. Six beef heifer calves were handled and bled every 2 weeks (control), 30 were left unhandled (naive). At 13, 21, 30, 39 and 47 weeks of age, a different group of naive heifers and the control heifers were bled every day for 5 days (puberty seen at 57·4 (s.e. 1·3) weeks). Thirty-nine dairy heifer calves were allocated to seven groups to receive adrenocorticotropic hormone (ACTH) at either 4, 7, 9, 16, 26, 36 or 46 weeks of age (puberty expected around 43 weeks of age). Plasma concentrations of cortisol increased at 21, 30 and 39 weeks of age in frequently handled and naive beef heifers; the increase was greater at these ages in the naive beef heifers (age and treatment P < 0·01). No age trend was apparent for plasma concentrations of cortisol and progesterone prior to ACTH injections (t = 0) in frequently handled dairy heifers. Adrenal progesterone secretion did not change with age in beef heifers, but naive beef heifers had greater plasma concentrations than frequently handled beef heifers. ACTH induced cortisol release in dairy heifers as early as 4 weeks of age (P < 0·05), but the response was greater in dairy heifers 16 weeks old and older (P < 0·05). A progesterone response to ACTH in dairy heifers was not seen until animals were 9 weeks old. It is concluded that as heifers mature reproductively, there is a parallel increase in the sensitivity of the adrenal gland to ACTH and handling stress.
Gonadotrophin Releasing Hormone (GnRH) is secreted in a pulsatile manner by the hypothalamus. GnRH is the major hormone controlling the pituitary-testicular axis and therefore influences aggressive and sexual behaviour in bulls. In 6 to 10 week old bull calves an increase in GnRH pulse frequency is responsible for a short-lived rise in circulating levels of LH. It has been shown that bulls with a higher rise in LH attain puberty at younger ages and have comparatively enhanced semen quality once they mature (Evans et al., 1995). Furthermore testicular growth has been enhanced in calves with a premature increase in LH brought about by GnRH treatment (Chandolia et al., 1997). This experiment tests the hypothesis that bull calves with increased GnRH pulsatility engage in more male-male mounting behaviour during this early period while the pattern of hormone secretion is becoming established. Studying this behaviour may give an indication of reproductive potential from as early as 8 weeks of age.
Wheat is often the largest single ingredient in piglet diets and therefore variation in quality may have a large effect on piglet performance. Currently there is no rapid method for the nutritive assessment of wheat. The livestock feed industry traditionally uses bushel weight as a predictor of nutritive value; however this assumption has recently been challenged by a literature review (Miller and Wilkinson, 1998) and by a weaner trial (Miller, Toplis, Arnold, Cook and Marshall, 2000). The aim of this experiment was to compare two more extreme bushel weights of Riband (64 v 78 kg/hl) than used in the previous experiment (Miller et al., 2000) when fed to weaned piglets with and without a xylanase enzyme. In order to amplify possible differences wheats were uncooked and included in the test diets at an atypically high level. We hypothesised that 78 kg/hl bushel weight would outperform 64kg/hl bushel weight (which is below the standard accepted by feed mills for feed wheat) and that enzyme supplementation would improve the performance of both wheats.
African horse sickness (AHS) was diagnosed for the first time in southern Portugal in autumn
1989, following outbreaks in Spain. AHS virus presence was confirmed by virus isolation and
serotyping. An eradication campaign with four sanitary zones was set up by Central Veterinary
Services in close collaboration with private organizations. Vaccination began on 6 October. In
February 1990, vaccination was extended to all Portuguese equines (170000 animals). There
were 137 outbreaks on 104 farms: 206 of the equidae present died (16%) or were slaughtered
(14%); 81·5% were horses, 10·7% were donkeys and 7·8% were mules. Clinical AHS occurred
more frequently in horses than donkeys and mules. In the vaccinated population, 82 animals
(62·2% horses and 37·8% mules and donkeys), died or were slaughtered due to suspected or
confirmed AHS. One year after ending vaccination, December 1991, Portugal was declared free
of AHS. Cost of eradication was US$1955513 (US$11·5/Portuguese equine).
Culicoides variipennis sonorensis Wirth & Jones and C. nubeculosus (Meigen) were orally infected with African horse sickness virus (AHSV) type 9 and subsequently incubated at 10, 15, 20 and 25°C (R.H. 80%±10%). A time course of infection rates and virus titres was recorded by assaying flies individually or in pools, and survival rates of flies were also estimated. Survival rates at 10, 15 and 20°C were very similar and 80–90% of flies remained alive after 14 days; at 25°C after the same period survival was reduced to 40%. None of the C. nubeculosus became persistently infected with AHSV, but the virus took longer to clear as the incubation temperature dropped. At temperatures of 10, 15, 20 and 25°C virus was undetectable on days 12, 8, 5, and 4 days post infection (dpi), respectively. In C. v. sonorensis both the infection rate and rate of virogenesis were related to temperature. At 25°C a maximum mean titre of 104.3 TCID50/fly was reached by 9 dpi and the infection rate remained between 60 and 80%. At 20°C virogenesis was slower and a maximum mean titre of 104.3 TCID50/fly was reached only after 23 days; the infection rate was also reduced to 50–70%. At 15°C there was an overall decline in virus titre with time, although between 12 and 15 dpi some pools of flies contained 103.0–104.0 TCID50/fly, demonstrating that virogenesis can occur. The infection rate at this temperature decreased dramatically to 0–15% after 9 dpi. At 10°C there was no detectable virogenesis and all pools tested at 13 dpi were negative. The apparent infection rate dropped to 0–5% between 13 and 35 days post infection. However, when surviving flies were then returned to 25 °C for 3 days the infection rate increased to 15.5%. It therefore appears that at low temperatures the virus does not replicate but infectious virus may persist at a level below that detectable by the usual assay systems. The implications of these findings for the epidemiology of AHS are discussed.
Growth rates for homoepitaxy of diamond (100) and (111) by hot-filament chemical vapor deposition were measured via in situ Fizeau interferometry and the surface morphologies were subsequently characterized by atomic force microscopy (AFM). (100)-oriented growth from 0.5% CH4 in H2 exhibited pure Arrhenius behavior, with an activation energy of 17±1 kcal/mol, up to a substrate temperature of 1100°C. Addition of oxygen to the feed gas resulted in an increased growth rate below 900°C, a maximum growth rate between 900 and 1000°C, and etching (of diamond) above 1050 - 1100°C. However, the presence of oxygen apparently had less effect on the surface morphology than did the (100)-to-(111) growth rate parameter α, determined directly from the relative growth rates of (100) and (111) substrates mounted side by side. During homoepitaxial growth from 0.5% CH4 in H2 at 875°C of ca. 1-micron-thick films,α = was 2.2 without oxygen and 1.3 for growth with 0.14% O2. The (100) film grown with α = 2.2 was quite smooth, while that with α = 1.3 was covered by numerous hillocks and penetration twins. AFM analysis revealed surprisingly little difference between the (111) films despite the considerable difference in α. Implications of these results for the growth mechanism are discussed.
As-polished and homoepitaxial diamond (100)- and (111)-oriented single crystals, natural diamond powders of 0.12-6 μm diameter, and high-pressure/hightemperature (HPHT) diamond powders of 50-100 μm diameter were treated in a microwave hydrogen plasma under four sets of conditions. Negligible changes in the weights (±10 μg) of the as-polished and homoepitaxial diamonds were observed.Post-treatment atomic force microscopy (AFM) showed a combination of smoothing and pit formation on (100) surfaces, the details of which were sensitive to the structure of the starting surface. Asymmetric pits formed on an as-polished (111) surface, but no qualitative changes in the structure of highly defective (100) and (111) films were observed. Natural diamond powders, which were quite irregular and rough prior to treatment, became markedly smoother and well-faceted, as observed by scanning electron microscopy (SEM). The degree of faceting was sensitive to plasma power level but was independent of H2 flow rate. The size and degree of faceting appeared to be the same after plasma treatment for isolated and closelypacked particles; however, the latter fused into a quasi-continuous film. “Regrown” crystallites were observed on the surfaces of synthetic type Ib diamond particles following plasma treatment. We argue that surface diffusion is the dominant mechanism for the observed morphological changes.
The severity of the trypanosomiasis problem in a particular location is traditionally assessed in terms of a challenge index – the product of some measure of tsetse abundance and infection rate – which is assumed to be proportional to the force of infection. However, this index masks variation in the force of infection between herds and among individuals within herds. It is also not comparable between sites since the relative abundance of tsetse to hosts may vary. We have studied spatial distribution of herds of cattle in relation to tsetse in The Gambia and calculated an index of challenge based on the ratio of vectors to hosts over the livestock ranging area. This index is strongly correlated with estimates of the force of infection calculated from the incidence of infection in susceptible zebu; and it provides information on heterogeneity in exposure of different herds to tsetse.
Growth and etch rates for diamond homoepitaxy have been measured in situ using Fizeau interferometry. Experiments were conducted in a hot-filament reactor using hydrogen, methane, and oxygen feed gases at a reactor pressure of 25 torr. The substrate temperature dependence for growth on diamond(lOO) was studied for 0.5% and 1% CH4 and 0–0.44% O2. Apparent activation energies of 17 and 5 kcal/mol were determined for growth from 0.5% and 1% CH4 in hydrogen, over the ranges of 700 – 1000 °C and 800 – 1050 °C, respectively. When a minimal amount of Oxygen was added to the feedstock, the growth-rate behavior was similar for that with pure methane. With greater amounts of added oxygen, growth rates were higher than those without Oxygen at low temperatures, proceeded through a maximum, and then decreased until etching was observed at high temperatures. Similar behavior was observed for growth from 1% CH4 with and without oxygen. We also measured the temperature dependence for etching of homoepitaxial diamond films in hydrogen with 0–0.1% O2, and observed etch rates of 0.01 – 0.1 microns/hr in the range of 950 – 1150 °C. We propose that oxygen facilitates diamond growth at low temperatures by enhancing the removal of both sp2- and sp3-bonded “errors” and/or by increasing the efficiency of carbon incorporation by roughening the diamond surface, and that these etching processes become dominant at high temperatures.
Application of surface science methods to single crystal diamond surfaces requires the preparation of clean, well-ordered surfaces and accurate measurement of substrate temperature. Cleaning of diamond (100) in H2SO4/HNO3/HClO4 produced several infrared absorption features between 1025 and 1275 cm-1, as observed by infrared multiple-internal-reflection spectroscopy. These modes are assigned to surface hydroxyl and bridge-bonded oxygen. Heating an oxidized surface to ca. 1130 °C caused disappearance of a surface hydroxyl mode centered at 1080 cm-1. We show by atomic force microscopy that an as-polished diamond (100) sample is covered by grooves and ridges several nm in height, implying a modest density of atomic steps. The surface of a diamond that underwent etching via numerous adsorption/desorption experiments in ultrahigh vacuum and was acid cleaned several times was essentially unchanged, indicating a minimal perturbation of the surface topography. The capability of Fizeau interferometry for accurate measurement of single-crystal diamond temperatures is demonstrated.
A country-wide survey of the distribution of tsetse flies Glossina morsitans submorsitans Newstead and G. palpalis gambiensis Vanderplank was carried out in The Gambia, during 1989–1990, using box traps at 1654 sites over an area of 10,000 km2 The general distribution of tsetse had changed little during the last 45 years. G. m. submorsitans was present in dry, canopied woodland throughout most of the country, but was absent from an area south of the River Gambia stretching from the coast to some 100 km inland. G. p. gambiensis occurred in evergreen forest and woodland near the coast, and in riparian habitats along the length of the River Gambia and its major tributaries. Nowhere in the country was more than 20 km from tsetse-infested areas. Five major foci of G. m. submorsitans infestation were identified. Demographic, climatic and environmental factors affect tsetse populations in The Gambia, but it is expected that these foci of infestation will persist for at least the next 5–10 years. The numbers of tsetse trapped, expressed as relative densities, were used to assess the extent and severity of losses from trypanosomiasis to different categories of livestock. Survey results such as these could be used to assess whether control measures to reduce tsetse challenge are likely to be economically viable by using techniques such as insecticide-impregnated targets, pour-ons or chemotherapy.
This paper commences by outlining the developments expected in en-route navigation capabilities in Western Europe and describes the current provision of surveillance employing monopulse SSRS. Following a brief review of GPS characteristics, it then considers the use of ADS, in conjunction with GPS, as an alternative and/or supplement to these ground-based systems. In the light of a simple cost comparison, it suggests that the space-based system could be very advantageous, particularly where new routes are to be established in areas with little or no ATS infrastructure. A final section discusses the possibility of using GPS for height-monitoring purposes as will be necessary when a reduced vertical separation minimum of iooo ft, is employed above FL290 in Europe, and elsewhere.
A novel method for chemical vapor deposition and atomic layer epitaxyusing radical precursors under medium vacuum conditions is being developed. Fluorine atoms are generated by thermal dissociation in a hot tube and abstract hydrogen atoms from precursor molecules injected immediately downstream of the source, generating radicals with completechemical specificity. The radical precursors are then transported to the growing substrate surface under nearly collision-free conditions. To date we have grown diamond films from CCl3 or CH3 radicals together with atomic hydrogen, generated by injecting CHCI3 or CH4 and H2 into the F atom stream at reactor pressures between 10−4 and 10−2 Torn This approach should be ideal for low-temperature growth and atomic layer epitaxy: growth rates remain relatively high because activation energies for radical reactions are typically small and because the cycle times for atomic layer epitaxy can be reduced to die msec range by fast gas-stream switching, and contamination and segregation are minimized by keeping the surface “capped” by chemisorbed intermediates.