Epitaxial gallium arsenide wafers

The preparation of GaAs epitaxial layers by a vapor transport process using AsCl3, Ga and H2 was pursued to provide epitaxial wafers suitable for the fabrication of transferred electron oscillators and amplifiers operating in the subcritical region. Both n-n(+) structures, and n(++)-n-n(+) sandwich structures were grown using n(+) (Si-doped) GaAs substrates. Process variables such as the input AsCl3 concentration, gallium temperature, and substrate temperature and temperature gradient and their effects on properties are presented and discussed

The short-term impact of the alcohol act on alcohol-related deaths and hospital admissions in Scotland: a natural experiment

Background and aim: The introduction of the Alcohol Act in Scotland on 1 October 2011, which included a ban on multi-buy promotions, was likely associated with a fall in off-trade alcohol sales in the year after its implementation. The aim of this study was to test if the same legislation was associated with reduced levels of alcohol-related deaths and hospital admissions in the 3-year period after its introduction. Design: A natural experiment design using time series data to assess the impact of the Alcohol Act legislation in Scotland. Comparisons were made with unexposed populations in the rest of Great Britain. Setting Scotland with comparable data obtained for geographical control groups in other parts of Great Britain. Participants: For alcohol-related deaths, a total of 17,732 in Scotland and 88,001 in England/Wales across 169 four-week periods between January 2001 and December 2013. For alcohol-related hospital admissions, a total of 121,314 in Scotland and 696,892 in England across 182 four-week periods between January 2001 and December 2014. Measurements: Deaths and hospital admissions in Scotland and control groups that were wholly attributable to alcohol for consecutive four-week periods between January 2001 and December 2014. Data were obtained by age, sex and area-based socioeconomic position. Findings: There was no evidence to suggest that the Alcohol Act was associated with changes in the overall rate of alcohol-related deaths [incidence rate ratio (IRR) 0.99, 95% confidence interval (0.91 to 1.07)] or hospital admissions [IRR 0.98 (0.95 to 1.02)] in Scotland. In control group analyses, the pseudo intervention variable was not associated with a change in alcohol-related death rates in England/Wales [IRR 0.99 (0.95 to 1.02)], but was associated with an increase in alcohol-related hospital admission rates in England [IRR 1.05 (1.03 to 1.07)]. In combined models, the interaction analysis did not provide support for a ‘net effect’ of the legislation on alcohol-related deaths in Scotland compared with England/Wales [IRR 0.99 (0.95 to 1.04)], but suggested a net reduction in hospital admissions for Scotland compared with England [IRR 0.93 (0.87 to 0.98)]. Conclusion: The implementation of the Alcohol Act in Scotland has not been associated clearly with a reduction in alcohol-related deaths or hospital admissions in the 3-year period after it was implemented in October 2011

Viral infections and asthma: An inflammatory interface?

© 2014 ERS. Asthma is a chronic inflammatory disease of the airways in which the majority of patients respond to treatment with corticosteroids and β2-adrenoceptor agonists. Acute exacerbations of asthma substantially contribute to disease morbidity, mortality and healthcare costs, and are not restricted to patients who are not compliant with their treatment regimens. Given that respiratory viral infections are the principal cause of asthma exacerbations, this review article will explore the relationship between viral infections and asthma, and will put forward hypotheses as to why virus-induced exacerbations occur. Potential mechanisms that may explain why current therapeutics do not fully inhibit virus-induced exacerbations, for example, β2-adrenergic desensitisation and corticosteroid insensitivity, are explored, as well as which aspects of virus-induced inflammation are likely to be attenuated by current therapy

Cold preservation of the human colon and ileum with University of Wisconsin solution

The inclusion of the colon in the intestinal graft resulted in worsening patient and graft outcome and increased the incidence of infection and rejection. In this study, we examine the role of ischemia on the barrier function of the epithelium during cold ischemia. Samples were collected from 15 harvested and transplanted human donor grafts (colon, 10; ileum, 6), which were immersed in University of Wisconsin (UW) solution. Ischemia (6, 12, 24, and 45 h) and reoxygenation were performed to evaluate the mucosal electrical status using the Ussing chamber technique. The functions of enterocytes and crypt cells were tested by glucose and theophylline challenge. Modified Park's classification was applied to evaluate the severity of mucosal damage under light microscopy. The colon had higher levels of baseline potential difference, short-circuit current, and resistance than the ileum during 6-48 h of ischemia. Colonic epithelial cells responded well to theophylline stimulation at 24 h of ischemia, while there was no ileal response. The colonic mucosa was histopathologically well preserved in UW solution for 48 h, and mucosal damage induced by reoxygenation was less than in the ileum. In conclusion, electrophysiologically and histopathologically, the colon is less susceptible to cold preservation damage than the ileum during storage with UW solution

Depigmented-polymerised allergoids favour regulatory over effector T cells: enhancement by 1α, 25-dihydroxyvitamin D3

Background: Allergen immunotherapy (SIT) is the only treatment for allergic disease capable of modifying disease long term. To reduce the risk of anaphylaxis from SIT, allergen-extracts have been modified by polymerisation with glutaraldehyde to reduce IgE binding. It is suggested that these allergoid extracts also have reduced T cell activity, which could compromise clinical efficacy. Effective SIT is thought to act through regulatory T cells (Tregs) rather than activation of effector T cells. There is no published data on the activity of modified extracts on Tregs.Results: We compared the capacity of modified (depigmented-polymerised) versus unmodified (native) allergen extracts of grass pollen and house dust mite to stimulate proliferation/cytokine production and to modulate Treg/effector T cell frequency in cultures of peripheral blood mononuclear cells (PBMC), from volunteers sensitised to both allergens in vitro. Depigmented-polymerised allergen extracts stimulated less proliferation of PBMC, and reduced effector cell numbers after 7 days in culture than did native extracts. However, the frequency of Foxp3+ Tregs in cultures were similar to those seen with native extract so that ratios of regulatory to effector T cells were significantly increased in cultures stimulated with depigmented-polymerised extracts. Addition of 1 alpha, 25-dihydroxyvitamin D3 further favoured Treg, and reduced effector cytokine production, but not interleukin-10.Conclusions: Depigmented-polymerised allergen extracts appear to favour Treg expansion over activation of effector T cells and this may relate to their demonstrated efficacy and safety in SIT. 1 alpha, 25-dihydroxyvitamin D3 further reduces effector T cell activation by allergen extracts and may be a useful adjuvant for SIT.</p

Peer feedback content and sender’s competence level in academic writing revision tasks: Are they critical for feedback perceptions and efficiency?

Peer feedback content is a core component of peer assessment, but the impact of various contents of feedback is hardly studied. Participants in the study were 89 graduate students who were assigned to four experimental and a control group. Experimental groups received a scenario with Concise General (CGF) or Elaborated Specific (ESF) feedback by a high or low competent peer. ESF by a high competent peer was perceived as more adequate, but led to more negative affect. Students in CGF groups outperformed ESF groups during treatment. Groups with a low competent peer outperformed groups with a high competent peer during the posttest. Feedback perceptions and performance were uncorrelated

Ground-state ammonia and water in absorption towards Sgr B2

We have used the Odin submillimetre-wave satellite telescope to observe the ground state transitions of ortho-ammonia and ortho-water, including their 15N, 18O, and 17O isotopologues, towards Sgr B2. The extensive simultaneous velocity coverage of the observations, >500 km/s, ensures that we can probe the conditions of both the warm, dense gas of the molecular cloud Sgr B2 near the Galactic centre, and the more diffuse gas in the Galactic disk clouds along the line-of-sight. We present ground-state NH3 absorption in seven distinct velocity features along the line-of-sight towards Sgr B2. We find a nearly linear correlation between the column densities of NH3 and CS, and a square-root relation to N2H+. The ammonia abundance in these diffuse Galactic disk clouds is estimated to be about (0.5-1)e-8, similar to that observed for diffuse clouds in the outer Galaxy. On the basis of the detection of H218O absorption in the 3 kpc arm, and the absence of such a feature in the H217O spectrum, we conclude that the water abundance is around 1e-7, compared to ~1e-8 for NH3. The Sgr B2 molecular cloud itself is seen in absorption in NH3, 15NH3, H2O, H218O, and H217O, with emission superimposed on the absorption in the main isotopologues. The non-LTE excitation of NH3 in the environment of Sgr B2 can be explained without invoking an unusually hot (500 K) molecular layer. A hot layer is similarly not required to explain the line profiles of the 1_{1,0}-1_{0,1} transition from H2O and its isotopologues. The relatively weak 15NH3 absorption in the Sgr B2 molecular cloud indicates a high [14N/15N] isotopic ratio >600. The abundance ratio of H218O and H217O is found to be relatively low, 2.5--3. These results together indicate that the dominant nucleosynthesis process in the Galactic centre is CNO hydrogen burning.Comment: 10 pages, 5 figure

Measuring Inequalities in the Distribution of Health Workers: The case of Tanzania.

The overall human resource shortages and the distributional inequalities in the health workforce in many developing countries are well acknowledged. However, little has been done to measure the degree of inequality systematically. Moreover, few attempts have been made to analyse the implications of using alternative measures of health care needs in the measurement of health workforce distributional inequalities. Most studies have implicitly relied on population levels as the only criterion for measuring health care needs. This paper attempts to achieve two objectives. First, it describes and measures health worker distributional inequalities in Tanzania on a per capita basis; second, it suggests and applies additional health care needs indicators in the measurement of distributional inequalities. We plotted Lorenz and concentration curves to illustrate graphically the distribution of the total health workforce and the cadre-specific (skill mix) distributions. Alternative indicators of health care needs were illustrated by concentration curves. Inequalities were measured by calculating Gini and concentration indices.\ud There are significant inequalities in the distribution of health workers per capita. Overall, the population quintile with the fewest health workers per capita accounts for only 8% of all health workers, while the quintile with the most health workers accounts for 46%. Inequality is perceptible across both urban and rural districts. Skill mix inequalities are also large. Districts with a small share of the health workforce (relative to their population levels have an even smaller share of highly trained medical personnel. A small share of highly trained personnel is compensated by a larger share of clinical officers (a middle-level cadre) but not by a larger share of untrained health workers. Clinical officers are relatively equally distributed. Distributional inequalities tend to be more pronounced when under-five deaths are used as an indicator of health care needs. Conversely, if health care needs are measured by HIV prevalence, the distributional inequalities appear to decline. The measure of inequality in the distribution of the health workforce may depend strongly on the underlying measure of health care needs. In cases of a non-uniform distribution of health care needs across geographical areas, other measures of health care needs than population levels may have to be developed in order to ensure a more meaningful measurement of distributional inequalities of the health workforce

Correlation of Nav1.8 and Nav1.9 sodium channel expression with neuropathic pain in human subjects with lingual nerve neuromas

Background: Voltage-gated sodium channels Nav1.8 and Nav1.9 are expressed preferentially in small diameter sensory neurons, and are thought to play a role in the generation of ectopic activity in neuronal cell bodies and/or their axons following peripheral nerve injury. The expression of Nav1.8 and Nav1.9 has been quantified in human lingual nerves that have been previously injured inadvertently during lower third molar removal, and any correlation between the expression of these ion channels and the presence or absence of dysaesthesia investigated. Results: Immunohistochemical processing and quantitative image analysis revealed that Nav1.8 and Nav1.9 were expressed in human lingual nerve neuromas from patients with or without symptoms of dysaesthesia. The level of Nav1.8 expression was significantly higher in patients reporting pain compared with no pain, and a significant positive correlation was observed between levels of Nav1.8 expression and VAS scores for the symptom of tingling. No significant differences were recorded in the level of expression of Nav1.9 between patients with or without pain. Conclusions: These results demonstrate that Nav1.8 and Nav1.9 are present in human lingual nerve neuromas, with significant correlations between the level of expression of Nav1.8 and symptoms of pain. These data provide further evidence that changes in expression of Nav1.8 are important in the development and/or maintenance of nerve injury-induced pain, and suggest that Nav1.8 may be a potential therapeutic target

‘Axis of evil or access to diesel?: spaces of new imperialism and the Iraq war’

The invasion of Iraq in 2003 was waged by the so-called ‘Coalition of the Willing’. This paper will examine how the war was a space in the ongoing geographical extension of global capitalism linked to U.S. foreign policy. Was it simply the decision by a unitary, hegemonic actor in the inter-state system overriding concerns by other states? Was it an imperialist move to secure the ‘global oil spigot’? Alternatively, did the use of military force reflect the interests and emergence of a transnational state apparatus? In this paper, we argue that the U.S. needs to be conceptualised as a specific form of state, within which and through which national and transnational capital operate to establish the interests of a national fraction of an Atlantic ruling class. It is these processes of class struggle and their relation to wider struggles over spaces of imperialism, which need to be at the centre of analysis