An optical mechanism for aberration of starlight

We present a physical-optics based theory of the physical mechanism for aberration of starlight. We apply non-relativistic and relativistic theories for wavefront image formation and include the effects of optically transmitting media within the sensor. We show that the sensors imaging properties combined with finite velocity of light fully accounts for aberration. That is, the influence of the moving sensor on the incident wavefront from the star fully explains aberration. Our treatment differs from all previous derivations because we include wavefront-imaging physics within the sensor model. Our predictions match Earth-sensor based measurements, but differ at larger sensor speeds from predictions of the special relativistic-based theory. While experimental uncertainty resulting from the low Earth-orbital velocity prevents experimental confirmation of the special relativistic model of aberration, we find that Earth-based sensors containing refractive optical media could experimentally differentiate between these competing descriptions and, in addition, yield an independent test of time dilation. We derive and present the details of such an experiment

Identifying the Azobenzene/Aniline reaction intermediate on TiO2-(110) : a DFT Study

Density functional theory (DFT) calculations, both with and without dispersion corrections, have been performed to investigate the nature of the common surface reaction intermediate that has been shown to exist on TiO2(110) as a result of exposure to either azobenzene (C6H5N═NC6H5) or aniline (C6H5NH2). Our results confirm the results of a previous DFT study that dissociation of azobenzene into two adsorbed phenyl imide (C6H5N) fragments, as was originally proposed, is not energetically favorable. We also find that deprotonation of aniline to produce this surface species is even more strongly energetically disfavored. A range of alternative surface species has been considered, and while dissociation of azobenzene to form surface C6H4NH species is energetically favored, the same surface species cannot form from adsorbed aniline. On the contrary, adsorbed aniline is much the most stable surface species. Comparisons with experimental determinations of the local adsorption site, the Ti–N bond length, the molecular orientation, and the associated C 1s and N 1s photoelectron core level shifts are all consistent with the DFT results for adsorbed aniline and are inconsistent with other adsorbed species considered. Possible mechanisms for the hydrogenation of azobenzene required to produce this surface species are discussed

Evaluation of the effectiveness of stainless steel cooking pots in reducing iron-deficiency anaemia in food aid-dependent populations

AbstractObjectiveTo evaluate the effectiveness of stainless steel (Fe alloy) cooking pots in reducing Fe-deficiency anaemia in food aid-dependent populations.DesignRepeated cross-sectional surveys. Between December 2001 and January 2003, three surveys among children aged 6–59 months and their mothers were conducted in 110 households randomly selected from each camp. The primary outcomes were changes in Hb concentration and Fe status.SettingTwo long-term refugee camps in western Tanzania.SubjectsChildren (6–59 months) and their mothers were surveyed at 0, 6 and 12 months post-intervention. Stainless steel pots were distributed to all households in Nduta camp (intervention); households in Mtendeli camp (control) continued to cook with aluminium or clay pots.ResultsAmong children, there was no change in Hb concentration at 1 year; however, Fe status was lower in the intervention camp than the control camp (serum transferrin receptor (sTfR) concentration: 6·8v. 5·9 μg/ml;P< 0·001). There was no change in Hb concentration among non-pregnant mothers at 1 year. Subjects in the intervention camp had lower Fe status than those in the control camp (sTfR concentration: 5·8v. 4·7 μg/ml;P= 0·003).ConclusionsDistribution of stainless steel pots did not increase Hb concentration or improve Fe status in children or their mothers. The use of stainless steel prevents rusting but may not provide sufficient amounts of Fe and strong educational campaigns may be required to maximize use. The distribution of stainless steel pots in refugee contexts is not recommended as a strategy to control Fe deficiency

Anaemia, iron status and vitamin A deficiency among adolescent refugees in Kenya and Nepal

AbstractObjectiveTo investigate the prevalence of anaemia (haemoglobin 8.3 μg ml−1) and vitamin A deficiency (serum retinol < 0.7 μmoll−1) in adolescent refugees.DesignCross-sectional surveys.SettingKakuma refugee camp in Kenya and seven refugee camps in Nepal.SubjectsAdolescent refugee residents in these camps.ResultsAnaemia was present in 46% (95% confidence interval (CI): 42–51) of adolescents in Kenya and in 24% (95% CI: 20–28) of adolescents in Nepal. The sensitivity of palmar pallor in detecting anaemia was 21%. In addition, 43% (95% CI: 36–50) and 53% (95% CI: 46–61) of adolescents in Kenya and Nepal, respectively, had iron deficiency. In both surveys, anaemia occurred more commonly among adolescents with iron deficiency. Vitamin A deficiency was found in 15% (95% CI: 10–20) of adolescents in Kenya and 30% (95% CI: 24–37) of adolescents in Nepal. Night blindness was not more common in adolescents with vitamin A deficiency than in those without vitamin A deficiency. In Kenya, one of the seven adolescents with Bitot's spots had vitamin A deficiency.ConclusionsAnaemia, iron deficiency and vitamin A deficiency are common among adolescents in refugee populations. Such adolescents need to increase intakes of these nutrients; however, the lack of routine access makes programmes targeting adolescents difficult. Adolescent refugees should be considered for assessment along with other at-risk groups in displaced populations

Acceptability and use of iron and iron-alloy cooking pots: implications for anaemia control programmes

Abstract Objective To evaluate the acceptability of iron and iron-alloy cooking pots prior to an intervention trial and to investigate factors affecting retention and use. Design Pre-trial research was conducted on five types of iron and iron-alloy pots using focus group discussions and a laboratory evaluation of Fe transfer during cooking was undertaken. Usage and retention during the subsequent intervention trial were investigated using focus group discussions and market monitoring. Setting Three refugee camps in western Tanzania. Subjects Refugee health workers were selected for pre-trial research. Mothers of children aged 6-59 months participated in the investigation of retention and use. Results Pre-trial research indicated that the stainless steel pot would be the only acceptable type for use in this population due to excessive rusting and/or the high weight of other types. Cooking three typical refugee dishes in stainless steel pots led to an increase in Fe content of 3·2 to 17·1 mg/100 g food (P < 0·001). During the trial, the acceptability of the stainless steel pots was lower than expected owing to difficulties with using, cleaning and their utility for other purposes. Households also continued to use their pre-existing pots, and stainless steel pots were sold to increase household income. Conclusions Pre-trial research led to the selection of a stainless steel pot that met basic acceptability criteria. The relatively low usage reported during the trial highlights the limitations of using high-value iron-alloy cooking pots as an intervention in populations where poverty and the availability of other pots may lead to sellin

National Prevalence of Micronutrient Deficiencies, Anaemia, Genetic Blood Disorders and Over- and Undernutrition in Omani Women of Reproductive Age and Preschool Children

A national cross-sectional survey was conducted to estimate the prevalence of anaemia, micronutrient deficiencies, haemoglobin disorders and over- and undernutrition in children and women of reproductive age in Oman. Wasting and stunting were found in 9.3% and 11.4% of children aged 0–59 months, respectively, while 4.2% were overweight or obese. In addition, 23.8% were anaemic and 10.2%, 9.5% and 10.6% had iron, vitamin A and vitamin D deficiencies, respectively. Sickle cell and β-thalassaemia genetic traits were present in 5.3% and 4.2% of children and 4.7% and 2.8% of women, respectively. Overall, 9.1% of Omani women were underweight and 59.2% were overweight or obese. The prevalence of anaemia was 27.8%, while iron, folate, vitamin B12 and vitamin D deficiencies affected 24.8%, 11.6%, 8.9% and 16.2%, respectively. Anaemia among both children and women and the prevalence of overweight and obesity in women are the most concerning nutritional problems in Oman.Keywords: Nutrition Disorders; Malnutrition; Micronutrients; Iron-Deficiency Anemia; Avitaminosis; Vitamin D Deficiency; Vitamin B 12 Deficiency; Oman

High awareness butlow coverage of a locally produced fortified complementary food in Abidjan, Côte d'Ivoire : findings from a cross-sectional survey

Poor complementary feeding practices among infants and young children in Côte d'Ivoire are major contributing factors to the country's high burden of malnutrition. As part of a broad effort to address this issue, an affordable, nutritious, and locally produced fortified complementary food product was launched in the Côte d'Ivoire in 2011. The objective of the current research was to assess various levels of coverage of the program and to identify coverage barriers. A cross-sectional household survey was conducted among caregivers of children less than 2-years of age living in Abidjan, Côte d'Ivoire. Four measures of coverage were assessed: "message coverage" (i.e., has the caregiver ever heard of the product?), "contact coverage" (i.e., has the caregiver ever fed the child the product?), "partial coverage" (i.e., has the caregiver fed the child the product in the previous month?), and "effective coverage" (i.e., has the caregiver fed the child the product in the previous 7 days?). A total of 1,113 caregivers with children between 0 and 23 months of age were interviewed. Results showed high message coverage (85.0%), moderate contact coverage (37.8%), and poor partial and effective coverages (8.8% and 4.6%, respectively). Product awareness was lower among caregivers from poorer households, but partial and effective coverages were comparable in both poor and non-poor groups. Infant and young child feeding (IYCF) practices were generally poor and did not appear to have improved since previous assessments. In conclusion, the results from the present study indicate that availability on the market and high awareness among the target population is not sufficient to achieve high and effective coverage. With market-based delivery models, significant efforts are needed to improve demand. Moreover, given the high prevalence of malnutrition and poor IYCF practices, additional modes of delivering IYCF interventions and improving IYCF practices should be considered

Users' Guides to the Medical Literature: How to Use an Article About Mortality in a Humanitarian Emergency

The accurate interpretation of mortality surveys in humanitarian crises is useful for both public health responses and security responses. Recent examples suggest that few medical personnel and researchers can accurately interpret the validity of a mortality survey in these settings. Using an example of a mortality survey from the Democratic Republic of Congo (DRC), we demonstrate important methodological considerations that readers should keep in mind when reading a mortality survey to determine the validity of the study and the applicability of the findings to their settings

Clinical Significance of Bronchodilator Responsiveness Evaluated by Forced Vital Capacity in COPD: SPIROMICS Cohort Analysis.

ObjectiveBronchodilator responsiveness (BDR) is prevalent in COPD, but its clinical implications remain unclear. We explored the significance of BDR, defined by post-bronchodilator change in FEV1 (BDRFEV1) as a measure reflecting the change in flow and in FVC (BDRFVC) reflecting the change in volume.MethodsWe analyzed 2974 participants from a multicenter observational study designed to identify varying COPD phenotypes (SPIROMICS). We evaluated the association of BDR with baseline clinical characteristics, rate of prospective exacerbations and mortality using negative binomial regression and Cox proportional hazards models.ResultsA majority of COPD participants exhibited BDR (52.7%). BDRFEV1 occurred more often in earlier stages of COPD, while BDRFVC occurred more frequently in more advanced disease. When defined by increases in either FEV1 or FVC, BDR was associated with a self-reported history of asthma, but not with blood eosinophil counts. BDRFVC was more prevalent in subjects with greater emphysema and small airway disease on CT. In a univariate analysis, BDRFVC was associated with increased exacerbations and mortality, although no significance was found in a model adjusted for post-bronchodilator FEV1.ConclusionWith advanced airflow obstruction in COPD, BDRFVC is more prevalent in comparison to BDRFEV1 and correlates with the extent of emphysema and degree of small airway disease. Since these associations appear to be related to the impairment of FEV1, BDRFVC itself does not define a distinct phenotype nor can it be more predictive of outcomes, but it can offer additional insights into the pathophysiologic mechanism in advanced COPD.Clinical trials registrationClinicalTrials.gov: NCT01969344T4