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The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural–geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status.
Mycobacterium marinum, a bacterium found in freshwater and saltwater, can infect persons with direct exposure to fish or aquariums. During December 2013, the New York City Department of Health and Mental Hygiene learned of four suspected or confirmed M. marinum skin or soft tissue infections (SSTIs) among persons who purchased whole fish from Chinese markets. Ninety-eight case-patients with non-tuberculous mycobacteria (NTM) SSTIs were identified with onset June 2013–March 2014. Of these, 77 (79%) were female. The median age was 62 years (range 30–91). Whole genome sequencing of clinical isolates revealed two main clusters and marked genetic diversity. Environmental samples from distributors yielded NTM though not M. marinum. We compared 56 case-patients with 185 control subjects who shopped in Chinese markets, frequency-matched by age group and sex. Risk factors for infection included skin injury to the finger or hand (odds ratio [OR]: 15·5; 95% confidence interval [CI]: 6·9–37·3), hand injury while preparing fish or seafood (OR 8·3; 95% CI 3·8–19·1), and purchasing tilapia (OR 3·6; 95% CI 1·1–13·9) or whiting (OR 2·7; 95% CI 1·1–6·6). A definitive environmental outbreak source was not identified.
The Antarctic Roadmap Challenges (ARC) project identified critical requirements to deliver high priority Antarctic research in the 21st century. The ARC project addressed the challenges of enabling technologies, facilitating access, providing logistics and infrastructure, and capitalizing on international co-operation. Technological requirements include: i) innovative automated in situ observing systems, sensors and interoperable platforms (including power demands), ii) realistic and holistic numerical models, iii) enhanced remote sensing and sensors, iv) expanded sample collection and retrieval technologies, and v) greater cyber-infrastructure to process ‘big data’ collection, transmission and analyses while promoting data accessibility. These technologies must be widely available, performance and reliability must be improved and technologies used elsewhere must be applied to the Antarctic. Considerable Antarctic research is field-based, making access to vital geographical targets essential. Future research will require continent- and ocean-wide environmentally responsible access to coastal and interior Antarctica and the Southern Ocean. Year-round access is indispensable. The cost of future Antarctic science is great but there are opportunities for all to participate commensurate with national resources, expertise and interests. The scope of future Antarctic research will necessitate enhanced and inventive interdisciplinary and international collaborations. The full promise of Antarctic science will only be realized if nations act together.
We present new multiband photometric results for ROTSE-I δ Sct stars and the Fourier decomposition analysis. Our result shows that most of the stars classified as ROTSE-I δ Sct stars seem to be W UMa type eclipsing variable stars.
This paper describes a multidisciplinary robust optimisation framework for UAV conceptual design. An in-house configuration designer system is implemented to generate the full sets of configuration data for a well-developed advanced UAV analysis tool. A fully integrated configuration designer along with the UAV analysis tool ensures that full sets of configuration data are provided simultaneously while the UAV configuration changes during optimisation. The computational strategy for probabilistic analysis is proposed by implementing a central difference method and fitting distribution for a reduced number of Monte Carlo Simulation sampling points. The minimisation of a new robust design objective function helps to enhance the reliability while other UAV performance criteria are satisfied. In addition, the fully integrated process and a probabilistic analysis strategy method demonstrate a reduction in the probability of failure under noise factors without any noticeable increase in design turnaround time. The proposed robust optimisation framework for UAV conceptual design case study yields a more trustworthy prediction of the optimal configuration and is preferable to the traditional deterministic design approach. The high fidelity analysis ANSYS Fluent 13 is performed to demonstrate the accuracy of proposed framework on baseline, deterministic and RDO configuration.
Undoped 69GaAs/71GaAs isotope superlattice structures grown by MBE on n-type GaAs substrates, doped by Si to ∼3×1018 cm−3, have been used to study Ga self-diffusion in GaAs by disordering reactions. In the temperature range of 850–960°C, the SIMS measured Ga self-diffusivity values showed an activation enthalpy of 4 eV, and are larger than previously compiled Ga self-diffusivity and Al-Ga interdiffusivity values obtained under thermal equilibrium and intrinsic conditions, which are characterized by a 6 eV activation enthalpy. SIMS, CV, and TEM characterizations showed that the as-grown superlattice layers were intrinsic which became p-type with hole concentrations up to ∼2×1017 cm−3 after annealing, because the layers contain carbon. Dislocations of a density of ∼106-107 cm−2 were also present. However, the factor responsible for the presently observed larger Ga self-diffusivity values appears to be Si outdiffusion from the substrate, which was determined using CV measurements. Outdiffusion of Si decreases the n value in the substrate which causes the release of excess Ga vacancies into the superlattice layers where the supersaturated Ga vacancies enhance Ga self-diffusion.
A total of 245 patients with confirmed 2009 H1N1 influenza were admitted to the intensive-care units of 28 hospitals (South Korea). Their mean age was 55·3 years with 68·6% aged >50 years, and 54·7% male. Nine were obese and three were pregnant. One or more comorbidities were present in 83·7%, and nosocomial acquisition occurred in 14·3%. In total, 107 (43·7%) patients received corticosteroids and 66·1% required mechanical ventilation. Eighty (32·7%) patients died within 30 days after onset of symptoms and 99 (40·4%) within 90 days. Multivariate logistic regression analysis showed that the clinician's decision to prescribe corticosteroids, older age, Sequential Organ Failure Assessment score and nosocomial bacterial pneumonia were independent risk factors for 90-day mortality. In contrast with Western countries, critical illness in Korea in relation to 2009 H1N1 was most common in older patients with chronic comorbidities; nosocomial acquisition occurred occasionally but disease in obese or pregnant patients was uncommon.
To understand paths towards higher efficiency (η) for copper-indium-gallium-(sulfur)-selenide [CIG(S)Se] solar cells, we investigated a variety of absorber composition grading schemes for various back-side gallium (Ga), front-side sulfur (S), and double-graded Ga composition depth profiles in TCAD 1D/2D simulations. We fitted experimental results of a Back-Side Graded (BSG) solar cell with our TCAD models, prior to investigating other grading and interface schemes. The BSG solar cell was fabricated on a High Productivity Combinatorial (HPC™) platform based on sputtering Cu(In,Ga) followed by selenization. Our TCAD simulation methodology for optimizing CIG(S)Se solar cells started with a sensitivity analysis using 1D Solar-cell CAPacitance Simulator (SCAPS)  by selecting a typical range of key model parameters and analyzing the impact on η. We then used a 2D commercially-available Sentaurus simulation tool  to incorporate wavelength-dependent optical characteristics. As a result, we provide insight in the impact of grading schemes on efficiency for a fixed ‘material quality’ equal to an in-house BSG solar cell. We also quantify the effects of interface layers like MoSe2 at the Mo/CIG(S)Se interface, and an inverted surface layer at the CIG(S)Se/CdS interface.
We present a new observational project to study the hierarchical triple stellar system Algol, concentrating on the semidetached eclipsing binary at the heart of the system. Over 140 high-resolution and high-S/N spectra have been secured, of which 80 are from FIES at the Nordic Optical Telescope, La Palma, and the remainder were obtained with BOES at the Bohyunsan Optical Astronomy Observatory in Korea. All three components were successfully detected by the method of spectral disentangling, which yields the individual spectra of the three stars and also high-quality spectroscopic elements for both the inner and outer orbits. We present a detailed abundance study for the mass-accreting component in the inner orbit, which holds information on the history of mass transfer in the close inner binary system. We also reveal the atmospheric parameters and chemical composition of the tertiary component in the outer orbit.
New CCD photometric observations of SZ Her were obtained between February and May 2008. More than 1,100 times of minimum light spanning more than one century were used for the period analysis. We find that the orbital period of SZ Her has varied due to a combination of two periodic variations, with cycle lengths of P3 = 85.8 yr and P4 = 42.5 yr and semi-amplitudes of K3 = 0.013 days and K4 = 0.007 days, respectively. The most reasonable explanation for them is a pair of light-time-travel (LTT) effects driven by the existence of two M-type companions with minimum masses of M3 = 0.22 M⊙ and M4 = 0.19 M⊙, located at nearly 2:1 mean motion resonance. Then, SZ Her is a quadruple system and the 3rd and 4th components would stay in the stable orbital resonance.
Amorphous GaN films have been deposited onto various substrates by ion-assisted deposition. The films were deposited at room temperature using nitrogen ion energies in the range 40-900 eV. Rutherford backscattering spectroscopy and nuclear reaction analysis show that the Ga:N atomic ratio is approximately one for films grown with ion energy near 500 eV; these films have the highest transparency. Films grown with ion energies below 300 eV are Ga rich, and show reduced transparency across the visible. Raman spectroscopy, x-ray diffraction, and transmission electron microscopy confirm the amorphous nature of the films. Annealing studies on a-GaN establish that the films begin to crystallise at a temperature of about 700 C. To investigate the local bonding environment of the Ga or N atoms, we have measured the extended x-ray absorption fine structure (EXAFS) of the transparent GaN films. The EXAFS results indicate that the films are dominated by heteropolar tetrahedral bonding, with a low density of homopolar bonds.
We report on a high transparency low resistance contact to p-GaN composed of a thin oxidized Ni/Au bilayer overcoated with indium tin oxide (NiO/Au/ITO). The NiO/Au/ITO layer shows a specific contact resistivity, c, of 1.8 × 10−3 Ωcm2 that is nearly ten times lower than conventional Ni/Au annealed under N2. Measurements on fully processed LEDs with a NiO/Au/ITO current spreading layer (CSL) show an operating voltage of around 4 V at 20 mA that is comparable to LEDs fabricated with a conventional Ni/Au CSL and a dramatic improvement over the previous ITO data. LED top surface light emission through the NiO/Au/ITO CSL is shown to be greater than that from LEDs with a conventional semi-transparent Ni/Au CSL. Taken together, these results demonstrate the feasibility of using NiO/Au/ITO as a CSL for high performance GaN LEDs.
This work investigates dislocation etch pits in epitaxial lateral overgrowth (ELO) GaN by wet chemical etching. A mixture of H2SO4 and H3PO4 was used as a dislocation etchant, and SEM and AFM were employed to observe the surface topography. For the as-grown sample, SEM images present the flat, smooth surface without any pits or hillocks. After the chemical etching, hexagonal shaped etch pits were observed at the edge of ELO GaN. AFM observation of etched ELO GaN displayed high densities of etch pits clustered in the “window” region and the coalescent line of two growing fronts. In contrast, the overgrowth region was nearly free of etch pits. Moreover, we observed that different sizes of etch pits dominated in “window” region and coalescent region. This implied different types dislocations dominated in these regions.
The growth mechanism of epitaxial BaTiO3 films on vicinal Nb-doped SrTiO3 (SrTiO3:Nb) (001) substrate surfaces was studied in terms of surface morphology, crystalline orientation, microstructure, and film/substrate interface. Well-oriented BaTiO3 thin films were grown on SrTiO3 substrates with well-defined terraces by pulsed laser deposition. The regularly terraced TiO2-terminated surfaces of vicinal SrTiO3:Nb (001) substrates were prepared by a definite chemical and thermal treatment. Under our conditions, BaTiO3 seems to grow with a layer-then-island (Stranski-Krastanov) growth mechanism. In order to investigate the orientation and crystallinity of the BaTiO3 films, x-ray diffraction and high-resolution transmission electron microscopy were performed. Ferroelectricity of the BaTiO3 films was proved by electrical measurements performed on Pt/BaTiO3/SrTiO3:Nb heterostructures.
Highly porous silica films with pore size in the nanometer scale are being extensively studied as potential candidates for interlevel dielectrics. Because these dielectric materials appear in the form of thin films with a thickness of only several thousand Angstroms, conventional techniques are difficult to be readily applied to study their structure and porosity. We employed small angle scattering in the grazing incidence geometry in this study. Using high resolution xray beamline with synchrotron radiation source, we demonstrate that the small angle x-ray scatteirng (SAXS) data of the porous films can be obtained. The structure of sol-gel derived silica - xerogel films on silicon substrate studied by specular reflectivity and grazing incidence small angle x-ray scattering (GISAXS) will be presented.
We have been investigating conversion of syngas (CO: H2) to higher alkanes [Fischer-Tropsch (F-T) Process] in 5 μm and 25 μm channel microreactors coated with sol-gel encapsulated Fe/Co-nanocatalysts. These nano-metal-catalysts were incorporated into the sol-gel matrix by two methods: 1) metal nitrate solutions; 2) metal oxide nanoparticles. Characterization of these catalysts containing Co and Fe in alumina and silica sol-gel has been carried out by several techniques. The surface area measurements by BET method show an average specific surface area of 285 m2/g for alumina and 300 m2/g for silica sol-gel encapsulated catalysts. In order to optimize the sol-gel preparation and deposition in the microchannels, the elemental composition of sol-gel encapsulated catalyst was examined by EDX. The SEM and AFM images of the reactors before and after deposition of the catalysts have also been studied. Hydrogenation-reduction efficiency of the activated Fe-Co catalysts and the level of poisoning after the reaction were estimated using a vibrating sample magnetometer (VSM). The result suggests more efficient reduction in the case of the nano-particle metal oxides compared to that derived from metal nitrate solutions. In overall, 85% of the catalyst is poisoned after 25 hrs of catalytic reaction. The surface area and the syngas conversion results indicate that silica sol-gel matrix may be a better catalyst support. For alumina sol-gel support, higher conversion of syn-gas is observed with 25 μm microreactor channels. For silica sol-gel, syngas conversion as high as 73% has been achieved by adding Ru as a promoter to the Fe/Co catalyst mixture.
Epitaxial TiC Ohmic and Schottky contacts to 4H-SiC were formed by a new deposition method, UHV co-evaporation with Ti and C60, at low temperature (< 500°C). We achieved a contact resistivity of 2 × 10−5Δcm2 at 25°C for as deposited Ohmic contacts on Al ion implanted 4H-Silicon carbide. The rectifying behavior of TiC Schottky contacts was also investigated using I-V and C-V. The measured Schottky barrier height (SBH) was 1.26 eV for n-type and 1.65 eV for p-type 4H-SiC using C-V measurements for frequencies ranging from 1kHz to 1MHz. LEED, RBS, XPS, and XRD measurements were performed to analyze composition ratio, interface reaction, and structural properties of the TiC epitaxial layer.
AℓN deposited by D.C. triode sputtering and spin-on, phosphorus-doped glass (PSG) layers on GaAs and InP were investigated as encapsulants. These films have similar expansion coefficients to both GaAs and InP, minimizing the amount of strain induced in the near-surface region of the underlying wafer. We have quantified this effect by direct measurements of the stress in the films and by using secondary ion mass spectrometry profiling to measure the redistribution of Cr and Fe in encapsulated GaAs and InP respectively during high temperature processing. The dopant redistribution is considerably less for the AℓN and PSG films compared to the more conventional SiO2 and Si3N4 layers. The interaction of the films with the substrate at elevated temperatures is minimal as determined by Auger profiling and the electrical properties of the surface after removal of the encapsulants. The composition of the films remains essentially constant after annealing, as measured by Rutherford backscattering, and the thickness uniformity over large wafer diameters (2″) can be excellent with close control of the deposition parameters. The activation characteristics of low dose, Si-implanted layers in GaAs using either PSG or AℓN are comparable to those obtained using capless annealing or SiO2 or Si3N4 encapsulation.
Using optical emission spectroscopy (OES), mass spectrometry (MS), and laser-induced fluorescence (LIF), we are investigating a number of glow-discharge reactions as a function of RF power, flow rates, partial pressures, and H2 dilution under realistic thin-film deposition conditions.In this paper we report on the preliminary results of two studies:
1)The formation of radical and polymeric species in SiH4 and Si2H6 plasmas, and
2)The characterization of SiF4 + H2 plasmas and the detection of HSiCl and HSiF in the plasmas of SiH2Cl2 and SiH2F2, respectively.