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This article presents the results of a program of radiocarbon dating and Bayesian modeling from the precontact Yup'ik site of Nunalleq (GDN-248) in subarctic southwestern Alaska. Nunalleq is deeply stratified, presenting a robust relative chronological framework of well-defined individual house floors abundant in ecofacts suitable for radiocarbon dating. Capitalizing on this potential, we present the results of one of the first applications of Bayesian statistical modeling of radiocarbon data from an archaeological site in the North American Arctic. Using these methods, we demonstrate that it is possible to generate robust, high-resolution chronological models from Arctic archaeology. Radiocarbon dates, procured prior to the program of dating and modeling presented here, suggested an approximately three-century duration of occupation at the site. The results of Bayesian modeling nuance this interpretation. While it is possible that there may have been activity for almost three centuries (beginning in the late fourteenth century), occupation of the dwelling complex, which dominates the site, was more likely to have endured for no more than a century. The results presented here suggest that the occupation of Nunalleq likely encompassed three generations beginning cal AD 1570–1630 before being curtailed by conflict around cal AD 1645–1675.
To outline the development of a smartphone-based tool to collect thrice-repeated 24 h dietary recall data in rural Nepal, and to describe energy intakes, common errors and researchers’ experiences using the tool.
We designed a novel tool to collect multi-pass 24 h dietary recalls in rural Nepal by combining the use of a CommCare questionnaire on smartphones, a paper form, a QR (quick response)-coded list of foods and a photographic atlas of portion sizes. Twenty interviewers collected dietary data on three non-consecutive days per respondent, with three respondents per household. Intakes were converted into nutrients using databases on nutritional composition of foods, recipes and portion sizes.
Dhanusha and Mahottari districts, Nepal.
Pregnant women, their mothers-in-law and male household heads. Energy intakes assessed in 150 households; data corrections and our experiences reported from 805 households and 6765 individual recalls.
Dietary intake estimates gave plausible values, with male household heads appearing to have higher energy intakes (median (25th–75th centile): 12 079 (9293–14 108) kJ/d) than female members (8979 (7234–11 042) kJ/d for pregnant women). Manual editing of data was required when interviewers mistook portions for food codes and for coding items not on the food list. Smartphones enabled quick monitoring of data and interviewer performance, but we initially faced technical challenges with CommCare forms crashing.
With sufficient time dedicated to development and pre-testing, this novel smartphone-based tool provides a useful method to collect data. Future work is needed to further validate this tool and adapt it for other contexts.
The problem of determining the intrinsic shapes of elliptical galaxies cannot be solved using photometry alone. Measuring rotation on the apparent major and minor axes adds a kinematic constraint, but does not significantly improve the situation. We find that having two more spectra, at the ±45° position angles, gives enough kinematic information that much tighter limits can be placed on the intrinsic axis ratios than are possible otherwise.
Public Health England conducts enhanced national surveillance of tetanus, a potentially life-threatening vaccine-preventable disease. A standardized questionnaire was used to ascertain clinical and demographic details of individuals reported with clinically suspected tetanus. The 96 cases identified between 2001 and 2014 were analysed. The average annual incidence was 0·13/million (95% confidence interval 0·10–0·16) of which 50·0% were male. Where reported, 70·3% of injuries occurred in the home/garden (45/64). Overall, 40·3% (31/77) cases were in people who inject drugs (PWID), including a cluster of 22 cases during 2003–2004. Where known (n = 68), only 8·8% were age-appropriately immunized. The overall case-fatality rate was 11·0% (9/82). All tetanus-associated deaths occurred in adults aged >45 years, none of whom were fully immunized. Due to the success of the childhood immunization programme, tetanus remains a rare disease in England with the majority of cases occurring in older unimmunized or partially immunized adults. Minor injuries in the home/garden were the most commonly reported likely sources of infection, although cases in PWID increased during this period. It is essential that high routine vaccine coverage is maintained and that susceptible individuals, particularly older adults, are protected through vaccination and are offered timely post-exposure management following a tetanus-prone wound.
Entropy maximising spatial interaction models have been widely exploited in a range of disciplines and applications: from trade and migration flows to the spread of riots and the understanding of spatial patterns in archaeological sites of interest. When embedded into a dynamic system and framed in the context of a retail model, the dynamics of centre growth poses an interesting mathematical problem, with bifurcations and phase changes, which may be addressed analytically. In this paper, we present some analysis of the continuous retail model and the corresponding discrete version, which yields insights into the effect of space on the evolving system, and an understanding of why certain retail centres are more successful than others. The slowly developing growths and the fast explosive growths that are of particular concern are explained in detail.
We apply the Barnes–Evans variant of the Baade–Wesselink method to Cepheids in the LMC and SMC in an attempt to determine the distance directly to individual stars in these galaxies and to determine the metallicity effect on the Cepheid period–luminosity relation. We now have K-band light curves for a sample of SMC stars as well as for many Cepheids in young clusters in the LMC. Using the FV, (V – K) calibration of Fouqué & Gieren (1997) we find preliminary evidence for a metallicity effect which makes metal poor Cepheids brighter. This is at odds with earlier results based on optical photometry and the reason is not entirely understood yet.
Within the field of environmental management and conservation, the concept of well-being is starting to gain traction in monitoring the socio-economic and cultural impact of interventions on local people. Here we consider the practical trade-offs policy makers and practitioners must navigate when utilizing the concept of well-being in environmental interventions. We first review current concepts of well-being before considering the need to balance the complexity and practical applicability of the definition used and to consider both positive and negative components of well-being. A key determinant of how well-being is operationalized is the identity of the organization wishing to monitor it. We describe the trade-offs around the external and internal validity of different approaches to measuring well-being and the relative contributions of qualitative and quantitative information to understanding well-being. We explore how these trade-offs may be decided as a result of a power struggle between stakeholders. Well-being is a complex, multi-dimensional, dynamic concept that cannot be easily defined and measured. Local perspectives are often missed during the project design process as a result of the more powerful voices of national governments and international NGOs, so for equity and local relevance it is important to ensure these perspectives are represented at a high level in project design and implementation.
This review summarises evidence for an association between vitamin D status and CVD and the mechanisms involved. Vitamin D3 is predominantly provided by the action of UVB from sunlight on skin. Average UK diets supply 2–3 μg/d vitamin D but diets containing at least one portion of oily fish per week supply about 7 μg/d. Pharmacological doses of vitamin D2 (bolus injection of 7500 μg or intakes >50 μg/d) result in a smaller increase in plasma 25(OH)D than those of D3 but physiological doses 5–25 μg/d seem equivalent. Plasma 25(OH)D concentrations are also influenced by clothing, obesity and skin pigmentation. Up to 40 % of the population have plasma 25(OH)D concentrations <25 nmol/l in the winter compared with <10 % in the summer. The relative risk of CVD death is 1·41 (95 % CI 1·18, 1·68) greater in the lowest quintile of plasma 25(OH)D according to meta-analysis of prospective cohort studies. Acute deficiency may inhibit insulin secretion and promote inflammation thus increasing the risk of plaque rupture and arterial thrombosis. Chronic insufficiency may increase arterial stiffness. There is no evidence to support claims of reduced CVD from existing trials with bone-related health outcomes where vitamin D was usually co-administered with calcium. Although several trials with cardiovascular endpoints are in progress, these are using pharmacological doses. In view of the potential toxicity of pharmacological doses, there remains a need for long-term trials of physiological doses of D2 and D3 with CVD incidence as the primary outcome.
Death certificate reports and laboratory-confirmed influenza deaths probably underestimate paediatric deaths attributable to influenza. Using US mortality data for persons aged <18 years who died during 28 September 2003 to 2 October 2010, we estimated influenza-attributable deaths using a generalized linear regression model based on seasonal covariates, influenza-certified deaths (deaths for which influenza was a reported cause of death), and occurrence during the 2009 pandemic period. Of 32 783 paediatric deaths in the death categories examined, 853 (3%) were influenza-certified. The estimated number of influenza-attributable deaths over the study period was 1·8 [95% confidence interval (CI) 1·3–2·8] times higher than the number of influenza-certified deaths. Influenza-attributable deaths were 2·1 (95% CI 1·5–3·4) times higher than influenza-certified deaths during the non-pandemic period and 1·1 (95% CI 1·0–1·8) times higher during the pandemic. Overall, US paediatric deaths attributable to influenza were almost twice the number reported by death certificate codes in the seasons prior to the 2009 pandemic.
We analysed a cross-sectional telephone survey of U.S. adults to assess the impact of selected characteristics on healthcare-seeking behaviours and treatment practices of people with influenza-like illness (ILI) from September 2009 to March 2010. Of 216 431 respondents, 8·1% reported ILI. After adjusting for selected characteristics, respondents aged 18–64 years with the following factors were more likely to report ILI: a diagnosis of asthma [adjusted odds ratio (aOR) 1·88, 95% CI 1·67–2·13] or heart disease (aOR 1·41, 95% CI 1·17–1·70), being disabled (aOR 1·75, 95% CI 1·57–1·96), and reporting financial barriers to healthcare access (aOR 1·63, 95% CI 1·45–1·82). Similar associations were seen in respondents aged ⩾65 years. Forty percent of respondents with ILI sought healthcare, and 14% who sought healthcare reported receiving influenza antiviral treatment. Treatment was not more frequent in patients with high-risk conditions, except those aged 18–64 years with heart disease (aOR 1·90, 95% CI 1·03–3·51). Of patients at high risk for influenza complications, self-reported ILI was greater but receipt of antiviral treatment was not, despite guidelines recommending their use in this population.
Evidence has accumulated over the past twenty years to suggest that the deep-sea environment is not as constant as was at one time thought, but exhibits temporal variations related to the seasonally in the overlying surface waters. Recent results from deep-moored sediment traps suggest that this coupling is mediated through the sedimentation of organic material, while observations in the Porcupine Seabight indicate that in this region, at least, there is a major and rapid seasonal deposition of aggregated phytodetritus to the sea-floor at slope and abyssal depths.
This paper summarises the results of the Porcupine Seabight studies over the past five years or so, using time-lapse sea-bed photography and microscopic, microbiological and chemical analyses of samples of phytodetritus and of the underlying sediment. The data are to some extent equivocal, but they suggest that the seasonal deposition is a regular and dramatic phenomenon and that the material undergoes relatively little degradation during its passage through the water column. The mechanisms leading to the aggregation of the phytodetritus have not been identified, and it is not yet known whether the phenomenon is geographically widespread nor whether it is of significance to the deep-living mid-water and benthic communities.
Magnetic nanocomposites have been successfully prepared by encapsulating nanosized entities of iron, cobalt, and nickel compounds in poly(amido-amine) (PAMAM) dendrimer hosts. Problems related to the instability of the magnetic structures under the influence of an external electromagnetic field have been overcome by using a solid polystyrene matrix to embed the dendrimer hosts containing the magnetic guests. SQUID magnetometry measurements on these nanocomposites showed that after subtraction of the diamagnetic polymer background, at 300 K all samples exhibited paramagnetic behavior, with susceptibilities of 1.14, 1.68, and 0.70 × 10−6 m3/kg for Fe-, Co-, and Ni-containing samples respectively. The temperature dependence for T<300 K showed typical paramagnetic behavior, with the susceptibility increasing for decreasing temperatures. Curie-Weiss (1/M vs. T) graphs displayed a linear behavior at high temperatures, with temperature axis intercepts (θ) occurring at –139 K (Fe), –16 K (Co), and 0 K (Ni). Negative deviations from Curie-Weiss behavior occurred at T<175 K for the Fe and T<25 K for the Co samples. Magnetic moments calculated from the high temperature Curie constant indicated that Fe, Co, and Ni possessed effective moments of 3.5, 4.4, and 2.8μB. The negative intercepts and the fact that these moments are larger than those expected for metallic transition metals are indicative that these species are probably present in an oxidized form. The low-temperature behavior indicates either superparamagnetic or soft ferromagnetic behavior.
When two magnetic films are separated by a nonmagnetic film, pinholes in the nonmagnetic film can allow direct contact and, thereby, direct magnetic exchange coupling between the two magnetic films. We have studied this coupling by having one of the magnetic films pinned and leaving the other free to switch at low field. The pinning is accomplished with test structures based on exchange bias and synthetic antiferromagnetic layers. Since the pinning strength increases sharply at low temperatures but orange-peel coupling does not, low-temperature (77 K) measurements appear to identify whether an observed coupling arises primarily from magnetic coupling through pinholes or primarily from orange-peel roughness. Our measurements appear to indicate that the observed coupling arises primarily from magnetic coupling through pinholes for Cu films less than 2.1 nm thick and for Al2O3films less than 0.6 nm thick but primarily from roughness-induced (orange-peel) magnetostatic coupling for larger thicknesses.
Recent experiments have confirmed the main features of the interlayer coupling we calculated for Fe/Cr multilayers. We discuss the origins of these features and present new results on the interlayer coupling for Fe/Mo(100) multilayered structures. We find they share many of the features seen in Fe/Cr structures; in particular the rapid oscillations of the coupling which are suppressed by the roughness of the interfaces in sputtered superlattices.
Two complementary techniques are used to study the electrical transport properties related to the use of diamonds as materials for ionizing radiation detectors. Transient photoconductivity using soft x-rays is used to probe the first few microns of the material, while ionizing particle-excited conductivity is used to probe the entire bulk of the material (1 millimeter). Both techniques measure the mean drift distance of free carriers, or the collection distance d. In addition, transient photoconductivity is able to extract the lifetimes and mobilities of the excited carriers. The collection distance measured by the two methods are in agreement, suggesting the material is homogeneous. At an applied field of 10 kV/cm, d is 25 to 30 microns, and, up to a field of 25 kV/cm, d has not saturated. The lifetime varies between 100 and 600 ps, and the mobility varies between 1000 and 4000 cm2/V-s, the range due to natural variations from sample to sample. The primary defects limiting the lifetime are believed to be nitrogen impurities and dislocations.
The electrical properties associated with carrier mobility, μ, and lifetime, τ, have been investigated for the chemical vapor deposited (CVD) diamond films using charged particle-induced conductivity and time resolved transient photo-induced conductivity. The collection distance, d, the average distance which electron and hole depart when driven by an applied electric field E, was measured by both methods. The collection distance is related to the carrier mobility and lifetime by d = μEτ Our measurements show that the collection distance increases linearly with sample thickness for CVD diamond films. The collection distance at the growth side of the CVD diamond film is comparable to that of single crystal natural type IIa diamond; at the substrate side of the film, the collection distance is near zero. No saturation of the collection distance is observed for film thickness up to 500 microns.
Plasma treatment and deposition techniques have been used to facilitate the covalent attachment of DNA to polymer surfaces. The variety of surface functional groups that can be created by plasma techniques enables different chemical conjugation routes to be explored. For example, a phosphodiester linkage can be used for surfaces with hydroxyl groups. Likewise, a carboxyamide linkage can be used for surfaces with carboxyl or amine groups. The primary application of the engineered materials has been the hybridization-based separation of multiplexed DNA sequencing products. Traditionally, sequencing reactions are performed individually on single templates. Multiplex sequencing offers reagent and time savings by permitting multiple sequencing reactions on single or multiple templates. The method developed uses recoverable DNA sequencing primers with additional “capture sequences” attached to the 5' end. The capture sequences are designed to be complementary to “binding sequences” covalently attached to the plasma-treated polymer supports. When a solution of the extended recoverable primers is exposed to a polymer support, primers with complementary capture sequences hybridize to the immobilized binding sequences. Contacting a multiplexed sample with a series of solid supports (each having a different binding sequence) selectively removes each set of sequencing products from the mixture. Washing each solid support, followed by releasing the hybridized DNA, results in isolated and purified sequencing products that are amenable to analysis by gel or capillary electrophoresis.
Photocurrent spectroscopy of InAs/GaAs self-assembled quantum dots, studied as a function of applied electric field, is used to probe the nature of the confined electronic states. A field asymmetry of the quantum confined Stark effect is observed, consistent with the dots possessing a permanent dipole moment. The sign of this dipole indicates that for zero field the hole wavefunction lies above that of the electron, in disagreement with the predictions of all recent calculations. Comparison with a theoretical model demonstrates that the experimentally determined alignment of the electron and hole can only be explained if the dots contain a nonzero and non-uniform Ga content. The role of two different carrier escape mechanisms, tunneling and thermal excitation, is studied.