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From a 45ks Chandra observation of V42G Oph we have obtained high-resolution X-ray spectra at moderate signal-to-noise, and a, good quality, uninterrupted lightcurve. The spectra are reasonably fit with a cooling flow model, similar to EX Hya and U Gem. Our analysis of the Chandra and additional X-ray/optical lightcurves reveals a persistent modulation at 4.2 hr from 1988 to 2003, likely the white dwarf spin period indicating an intermediate polar nature for V426 Oph.
Among young Samoan children, diet may not be optimal: in 2015, 16·1 % of 24–59-month-olds were overweight/obese, 20·3 % stunted and 34·1 % anaemic. The present study aimed to identify dietary patterns among 24–59-month-old Samoan children and evaluate their association with: (i) child, maternal and household characteristics; and (ii) nutritional status indicators (stunting, overweight/obesity, anaemia).
A community-based, cross-sectional study. Principal component analysis on 117 FFQ items was used to identify empirical dietary patterns. Distributions of child, maternal and household characteristics were examined by factor score quintiles. The regression of nutritional status indicators v. these quintiles was performed using logistic regression models.
Ten villages on the Samoan island of Upolu.
A convenience sample of mother–child pairs (n 305).
Two dietary patterns, modern and neo-traditional, emerged. The modern pattern was loaded with ‘westernized’ foods (red meat, condiments and snacks). The neo-traditional pattern included vegetables, local starches, coconuts, fish and poultry. Following the modern diet was associated with urban residence, greater maternal educational attainment, higher socio-economic status, lower vitamin C intake and higher sugar intake. Following the neo-traditional diet was associated with rural residence, lower socio-economic status, higher vitamin C intake and lower sugar intake. While dietary patterns were not related to stunting or anaemia, following the neo-traditional pattern was positively associated with child overweight/obesity (adjusted OR=4·23, 95 % CI 1·26, 14·17, for the highest quintile, P-trend=0·06).
Further longitudinal monitoring and evaluation of early childhood growth and development are needed to understand the influences of early diet on child health in Samoa.
Ice deformation and basal motion characterize the dynamical behavior of the Greenland ice sheet (GrIS). We evaluate the contribution of basal motion from ice deformation measurements in boreholes drilled to the bed at two sites in the western marginal zone of the GrIS. We find a sustained high amount of basal motion contribution to surface velocity of 44–73% in winter, and up to 90% in summer. Measured ice deformation rates show an unexpected variation with depth that can be explained with the help of an ice-flow model as a consequence of stress transfer from slippery to sticky areas. This effect necessitates the use of high-order ice-flow models, not only in regions of fast-flowing ice streams but in all temperate-based areas of the GrIS. The agreement between modeled and measured deformation rates confirms that the recommended values of the temperature-dependent flow rate factor A are a good choice for ice-sheet models.
Young children are particularly vulnerable to malnutrition as nutrition transition progresses. The present study aimed to document the prevalence, coexistence and correlates of nutritional status (stunting, overweight/obesity and anaemia) in Samoan children aged 24–59 months.
A cross-sectional community-based survey. Height and weight were used to determine prevalence of stunting (height-for-age Z-score <−2) and overweight/obesity (BMI-for-age Z-score >+2) based on WHO growth standards. Anaemia was determined using an AimStrip Hemoglobin test system (Hb <110 g/l).
Ten villages on the Samoan island of Upolu.
Mother–child pairs (n 305) recruited using convenience sampling.
Moderate or severe stunting was apparent in 20·3 % of children, 16·1 % were overweight/obese and 34·1 % were anaemic. Among the overweight/obese children, 28·6 % were also stunted and 42·9 % anaemic, indicating dual burden of malnutrition. Stunting was significantly less likely among girls (OR=0·41; 95 % CI 0·21, 0·79, P<0·01) than boys. Overweight/obesity was associated with higher family socio-economic status and decreased sugar intake (OR per 10 g/d=0·89, 95 % CI 0·80, 0·99, P=0·032). The odds of anaemia decreased with age and anaemia was more likely in children with an anaemic mother (OR=2·20; 95 % CI 1·22, 3·98, P=0·007). No child, maternal or household characteristic was associated with more than one of the nutritional status outcomes, highlighting the need for condition-specific interventions in this age group.
The observed prevalences of stunting, overweight/obesity and anaemia suggest that it is critical to invest in nutrition and develop health programmes targeting early childhood growth and development in Samoa.
Started its regular, daily operational phase in 2011, by the occasion of the Symp264 in the XXVII IAU GA at Rio de Janeiro, the results so far obtained show that the Heliometer of the Observatorio Nacional fulfilled its planed performance of single measurement to the level of few tens of milli-arcsecond, freely pivoting around the heliolatitudes without systematic deviations or error enhancement. We present and discuss the astrometric additions required on ground based astronomic programs. We also discuss instrumental and observations terms, namely the constancy of the basic heliometric angle, against which the measurements are made, and the independence to meteorological and pointing conditions.
We show that CSD processing can be optimized in order to achieve columnar structured BaTiO3 and SrTiO3 thin films at elevated temperatures. In addition to these, columnar grain growth was also obtained for films of the solid solution (Ba0.7Sr0.3)TiO3 By controlling the film formation process, polycrystalline and columnar grained thin films were grown on Pt coated Si substrates at temperatures between 750° and 800°. The films were analyzed by glancing incidence X-ray diffraction and scanning electron microscopy. Detailed analysis on the thin films’ microstructure was performed by means of transmission electron microscopy. Based on these data, the film formation process is discussed with respect to process control and precursor chemistry. Differences in the crystallization process of BaTiO3 thin films compared to SrTiO3 films are pointed out.
The relationship between structural distortions and resistivity in pulsed laser deposited La2/3Ca1/3MnO3 (LCMO) and La2/3Ca1/3MnO3 (LSMO) thin films was investigated by x-ray diffraction (XRD), transmission electron microscopy (TEM) and resistivity measurements. The growth defects inherent to annealed films were characterized, and then additional defects were introduced by radiation damage. Epitaxially grown films on (100) LaA1O3 substrates exhibited three primary types of growth defects: interface strain, column boundary mismatch, and column rotation. High resolution TEM measurements show well-ordered regions of film that offer low resistance paths for current flow around growth defects. A series of annealed samples were irradiated with 6 Mev Si+3 ions to produce 0.006 to 0.024 displacements per atom (dpa) in LCMO films, and 0.028 to 0.14 dpa in LSMO films. The peak resistance temperature (Tp) was found to depend strongly on defect concentration, varying from 235K ± 15K for the unirradiated LCMO films to 95K for 0.018 dpa. At 0.024 dpa, the LCMO film was insulating at all temperatures. LSMO films showed a downward shift in Tp from 300K for an unirradiated film to 250K for 0.028 dpa, and complete insulating behavior for 0.14 dpa.
The structure of epitaxial BaTiO3 thin films prepared by hydrothermal synthesis on (001) SrTiO3 substrates was studied by transmission electron microscopy (TEM). The growth evolution was followed from initial island formation, through island impingement and fusion. Plan view and cross-section imaging demonstrated that the films grew by an unusual islanding mechanism. Electron diffraction showed the islands and the fully formed film are single crystal with mosaic character and in all cases strain relaxed. Cross-section TEM of the early growth films showed a several monolayer thick interfacial layer and the film/substrate region had no misfit dislocations. In the fully formed films, this interfacial layer was not observed, however a clear misfit dislocation network was observed. Defects analysis shows that the misfit dislocations have pure edge character with <100> Une directions, and <010> Burgers vectors (parallel to the film/substrate interface).
Possible equilibrium domain structures due to elastic interactions between the film and the substrate as a result of a cubic-tetragonal transformation observed in epitaxial perovskite ferroelectric films are analyzed. The formation of both two- and three-domain states is taken into account. A stability map which shows domain stability regions as a function of temperature is developed in coordinates of misfit strain and tetragonality of the lattice of the ferroelectric phase. Misfit dislocation generation at the growth temperature is found to have a profound effect on domain selection. As an example a PbTiO3(001) film grown on a MgO(001) substrate is considered and theoretical findings are compared with experimental results in the literature.
Here we present our recent work on the fabrication of high crystalline and optical quality ZnO films on sapphire (001) by pulsed laser deposition. The influence of deposition parameters such as the substrate temperature, oxygen pressure, laser fluence, and pulse repetition rate on the crystalline quality of ZnO layers has been studied. The Ω-rocking curve FWHM of the (002) peak for the films grown at 750°, oxygen pressure 10−5 Torr was 0.17°. The XRD-Ф scans studies revealed that the films were epitaxial with a 30° rotation of the unit cell with respect to the sapphire to achieve a low energy configuration for epitaxial growth. The high degree of crystallinity was confirmed by ion channeling technique providing a minimum Rutherford backscattering yield of 2–3% in the near surface region (-2000Å). The atomic force microscopy revealed smooth hexagonal faceting of the films. The optical absorption edge measured by UV-Visible spectroscopy was sharp at 383 nm. Excellent crystalline properties of these epi-ZnO/sapphire heterostractures are thus promising for III-V nitride heteroepitaxy.
The relationship between the magnetic and crystalline microstructure of SrRu03 thin films is analyzed using transmission electron microscopy. Regions with a stripe magnetic domain structure in different orientations are observed in Lorentz imaging mode when the specimens are zero-field-cooled through the ferromagnetic transition temperature, Tc ≈ 150K. The different orientations of the stripe regions correspond to different crystallographic domains as determined by electron diffraction and magnetic image contrast; all of the six possible orientations of the orthorhombic SrRuO3 structure grown epitaxially on a SrTiO3 cubic substrate are identified. The results show that the uniaxial anisotropy indicated for these multi(crystal)domain films is the same as that determined for single crystal films by bulk magnetization measurements, and is therefore primarily magnetocrystalline in nature.
Multicomponent oxide films are needed to meet the increasing demands of the electronics industry. Three main methods that involve oxidation of a metallic substrate are thermal, anodic and plasma oxidation. Today we do not have an adequate fundamental physical-chemical model of how multicomponent oxides evolve on alloys under these oxidizing conditions to design a wide range of materials for electronic devices. The three methods will be discussed in terms of physical/chemical parameters that influence the chemical nature and structure of the resulting oxides. By using surface studies of the oxidation behavior of numerous metals and alloys we have been able to delineate the factors which are most important to the oxide formation process and provide insight into the prediction of oxide layer structures. The electrochemical processes that occur during the materials reaction with a chosen environment will be used to discuss the physical and chemical mechanisms involved. Intrinsic and extrinsic electric fields will be shown to influence the chemical and structural nature of the resulting oxide structures. Examples will be presented from a number of metal and alloy systems that have been examined in our laboratory. These include Al, Ti, Zr, Nb, Mn, Cu and Ni and some of their selected alloys. The models that have developed from these studies are providing some predictive power in how the complex oxide overlayer will be chemically speciated and on its structure.
The ability to fabricate sensitive and stable gas sensors which can detect low concentrations of gaseous species is necessary for many critical applications such as environmental safety monitoring. Although highly sensitive gas sensors have been produced by dispersion of catalytic metals on oxide sensing films, fouling of catalysts can cause instability in sensor performance. We have examined an approach which involves fine tuning the microstructure of tin oxide sensing films by vapor depositing an ultra-thin film of seed layer metals prior to tin oxide deposition. Metals including Fe, Sn and Pt have been investigated for their influence on tin oxide growth. Systematic studies of the growth mechanism and microstructure of CVD tin oxide using four-element arrays of “microhotplates” have revealed a number of different film morphologies which result from seeding. Enhancements in sensitivity for seeded growth relative to unseeded growth suggest a method of producing sensitive gas sensors which may not require the addition of surface catalytic layers. In this study we also demonstrate the use of microhotplates not only as sensing devices, but as excellent platforms for materials research.
Within Beck's cognitive model of depression, little is known about the mechanism(s) by which activated self-schemas result in the production of negative thoughts. Recent research has demonstrated that inhibitory dysfunction is present in depression, and this deficit is likely valence-specific. However, whether valence-specific inhibitory deficits are associated with increased negative cognition and whether such deficits are specific to depression per se remains unexamined. The authors posit the theory that inhibitory dysfunction may influence the degree to which activated self-schemas result in the production of depressive cognition.
Individuals with major depressive disorder (MDD, n=43) versus healthy (n=36) and non-depressed anxious (n=32) controls were assessed on the Prose Distraction Task (PDT), a measure of cognitive inhibition, and the Stop-Signal Task (SST), a measure of motor response inhibition. These two tasks were modified in order to present emotionally valenced semantic stimuli (i.e. negative, neutral, positive).
Participants with MDD demonstrated performance impairments on the PDT, which were most pronounced for negatively valenced adjectives, relative to both control groups. Moreover, these impairments correlated with self-report measures of negative thinking and rumination. Conversely, the performance of the MDD participants did not differ from either control group on the SST.
Implications of these findings for understanding the mechanisms underlying the development and maintenance of depressive cognition are discussed.
We present the first results from our next-generation microlensing survey, the SuperMACHO project. We are using the CTIO 4m Blanco telescope and the MOSAIC imager to carry out a search for microlensing toward the Large Magellanic Cloud (LMC). We plan to ascertain the nature of the population responsible for the excess microlensing rate seen by the MACHO project. Our observing strategy is optimized to measure the differential microlensing rate across the face of the LMC. We find this derivative to be relatively insensitive to the details of the LMC's internal structure but a strong discriminant between Galactic halo and LMC self lensing. In December 2003 we completed our third year of survey operations. 2003 also marked the first year of real-time microlensing alerts and photometric and spectroscopic followup. We have extracted several dozen microlensing candidates, and we present some preliminary light curves and related information. Similar to the MACHO project, we find SNe behind the LMC to be a significant contaminant - this background has not been completely removed from our current single-color candidate sample. Our follow-up strategy is optimized to discriminate between SNe and true microlensing.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html
Spectroscopic Properties, Fundamental Parameters and Modelling
S. L. Hawley, Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA,
I. N. Reid, Palomar Observatory, Caltech, Pasadena, CA 91125, USA,
J. G. Tourtellot, Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
We report on magnetic activity and luminosity function results from our field and cluster surveys of low mass stars. Magnetic activity in M dwarfs has several notable effects on the colors, magnitudes and molecular bandstrengths. The presence of activity only up to a limiting mass (color, magnitude) in a coeval population can be used as an age indicator. We have calibrated several age-activity relations using new observations of dMe stars in M67 to anchor the relations at large age. The changes in activity strength along the M dwarf sequence are discussed. The luminosity functions for several clusters show evidence for mass segregation and two clusters appear to have lost their low mass population. Unusually rapid dynamical evolution or a skewed initial mass function could account for these results. Either explanation would have implications for the number of brown dwarfs and very low mass stars expected in the field at the present epoch.
We have been carrying out large surveys of M dwarfs in the field (Reid et al. 1995, hereafter PMSU1, Hawley, Gizis & Reid 1996, hereafter PMSU2) and in nearby open clusters (Hawley, Tourtellot & Reid 1998, hereafter HTR98). Although these stars, on the whole, might not qualify as “very low mass” (VLM) stars for this conference, they are interesting to study in order to understand the properties that might affect stars even further down the main sequence.
Conductive SrRuO3 thin films were epitaxially grown on (100) LaAlO3 substrates by pulsed laser deposition over a temperature range from 650 °C to 825 °C. Well-textured films exhibiting a strong orientation relationship to the underlying substrate could be obtained at a deposition temperature as low as 450 °C. The degree of crystallinity of the films improved with increasing deposition temperature as confirmed by x-ray diffraction, transmission electron microscopy, and scanning tunneling microscopy. Scanning electron microscopy revealed no particulates on the film surface. The resistivity of the SrRuO3 thin films was found to be a strong function of the crystallinity of the film and hence the substrate temperature during film deposition. A residual resistivity ratio (RRR = ρ300 K/ρ4.2 K) of more than 8 was obtained for the SrRuO3 thin films deposited under optimized processing conditions.
A prospective study was conducted of all referrals to the emergency psychiatric service of an inner-London hospital over one year. There were 53 individuals who presented with the specific and spontaneous complaint of suicidal ideation without any accompanying act of self-harm. The main diagnoses in this group were personality disorders (40%) and alcohol dependence (15%); only 13% were suffering from depressive illness. Members of the group differed from the other 369 presenters to the service in that they were less likely to be accorded a diagnosis of a defined mental illness, twice as likely to have a criminal record, and more likely to have a previous history of deliberate self-harm. A quarter of the suicidal complainants were admitted to hospital following assessment.
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