1,761 research outputs found
Phase control and photocatalytic properties of nano-sized titania particles by gas-phase pyrolysis of TiCl4
No full textNanometer size titania particles smaller than 60 nm were prepared by gas-phase pyrolysis of TiCl(4). The rutile content of nano-sized titania particles was controlled by changing the preparation temperature from 700 to 1100 degreesC. It was found that mixed-phase titania nanoparticles containing about 11% of rutile, which were prepared at 810 degreesC showed higher photoactivity than that of as-prepared pure anatase one as well as Degussa P25. Pure anatase titania nanoparticles prepared at 700 degreesC had much lower photoactivity compared with Degussa P25 or lab-made other samples which have some rutile phase since they have low crystallinity. So, the anatase titania nanoparticles prepared at 700 degreesC was thermally post-treated in order to improve the crystallinity. As a result, the photoactivity was improved as the post-treatment temperature increases up to 800 degreesC by which no significant rutile phase was formed. However, the improved photoactivity of pure anatase nanoparticles by the post-treatment was still smaller than all lab-made others which were not post-treated and had some rutile phase. From this result, it was concluded that the post heat treatment of pure anatase nanoparticles obtained by the gas-phase reaction at a low temperature is not helpful to prepare high photoactive titania nanoparticles. So, when titania nanoparticles are prepared by a gas-phase synthetic route, the direct preparation of high crystalline nanoparticles at high reaction temperature is recommended to obtain high photoactivity as long as no significant rutile phase is formed. (C) 2004 Published by Elsevier B.V.Center for Ultramicrochemical Process System
Short-interval observational data to inform clinical trial design in Huntington's disease.
No full textOBJECTIVES: To evaluate candidate outcomes for disease-modifying trials in Huntington's disease (HD) over 6-month, 9-month and 15-month intervals, across multiple domains. To present guidelines on rapid efficacy readouts for disease-modifying trials. METHODS: 40 controls and 61 patients with HD, recruited from four EU sites, underwent 3 T MRI and standard clinical and cognitive assessments at baseline, 6 and 15 months. Neuroimaging analysis included global and regional change in macrostructure (atrophy and cortical thinning), and microstructure (diffusion metrics). The main outcome was longitudinal effect size (ES) for each outcome. Such ESs can be used to calculate sample-size requirements for clinical trials for hypothesised treatment efficacies. RESULTS: Longitudinal changes in macrostructural neuroimaging measures such as caudate atrophy and ventricular expansion were significantly larger in HD than controls, giving rise to consistently large ES over the 6-month, 9-month and 15-month intervals. Analogous ESs for cortical metrics were smaller with wide CIs. Microstructural (diffusion) neuroimaging metrics ESs were also typically smaller over the shorter intervals, although caudate diffusivity metrics performed strongly over 9 and 15 months. Clinical and cognitive outcomes exhibited small longitudinal ESs, particularly over 6-month and 9-month intervals, with wide CIs, indicating a lack of precision. CONCLUSIONS: To exploit the potential power of specific neuroimaging measures such as caudate atrophy in disease-modifying trials, we propose their use as (1) initial short-term readouts in early phase/proof-of-concept studies over 6 or 9 months, and (2) secondary end points in efficacy studies over longer periods such as 15 months
A new HgMn star HD 196821
No full textIn this study, we present the chemical abundance analysis of HD 196821. The spectra of HD 196821 was obtained at the TUBITAK National Observatory using the Coude Echelle spectrograph attached to the 1.5 m telescope. We determined the atmospheric parameters of HD 196821: T-eff=10600K, log g=3.6, nu(mic)=0 km/s, and [Fe/H]=0.16 dex. HD 196821 shows an overabundance of 85 times solar for Mn and 208,930 times solar for Hg. This strongly suggests that the star should be classified as an HgMn star
Lumbar radiculopathy and fracture risk: A Korean nationwide population-based cohort study
No full textIntroduction: Lumbar radiculopathy is a common disease with a high economic burden, and fractures in adults are a significant public health problem. However, studies of the relationship between lumbar radiculopathy and fractures are scarce. We investigated the fracture risk in patients with lumbar radiculopathy. Methods: This nationwide retrospective cohort study identified 815,101 patients with lumbar radiculopathy and randomly matched individuals without lumbar radiculopathy (1:1) who were included in the Korean National Health Insurance System in 2012. Cox proportional hazards regression analyses were performed to calculate the hazard ratio (HR) for fracture risk in patients with lumbar radiculopathy. Results: The study included 301,347 patients with lumbar radiculopathy and matched 289,618 individuals without lumbar radiculopathy. Compared to individuals without lumbar radiculopathy, patients with lumbar radiculopathy had a 27 % increased fracture risk (adjusted HR = 1.27, 95 % confidence interval = 1.24–1.31). The Kaplan-Meier plot showed a significantly higher fracture incidence in patients with lumbar radiculopathy than in individuals without lumbar radiculopathy at all times. Conclusion: Lumbar radiculopathy is significantly associated with fracture risk
Anonymous HD video streaming
No full textNo scalable privacy-enhancing technologies exists that is capable of anonymous HD video streaming. Our paper discusses the new anonymizer built into Tribler, a social content-sharing client. With anonymous HD-video streaming as the main objective requirements as at least 10 Mbit/s throughput, user bandwidth donations and NAT-traversal are defined. Using the Tribler API and related tools as Dispersy the ProxyCommunity is designed. This community of proxies provides peer discovery, onion routing and multi-tunnel proxying. Our system evolved through various stages. From the initial standalone routing prototype, to the first Tribler version. This was followed by profiling to achieve performance improvements. Finally the version with libtorrent and cryptography-readyness was implemented. Our performance evaluation shows that the proxy community is able to discover others on the network effectively and built circuits with them. Over these circuits the required 10 Mbit/s throughput for HD streaming has been achieved. Preliminary real-world testing shows that the system works in the wild. However more testing needs to be done and important work on our security model remains.Parallel and Distributed SystemsElectrical Engineering, Mathematics and Computer Scienc
Haploinsufficiency of the ESCRT Component HD-PTP Predisposes to Cancer
No full textSummaryEndosomal sorting complexes required for transport (ESCRT) drive cell surface receptor degradation resulting in attenuation of oncogenic signaling and pointing to a tumor suppressor function. Here, we show that loss of function of an ESCRT protein (HD-PTP encoded by the PTPN23 gene, located on the tumor suppressor gene cluster 3p21.3) drives tumorigenesis in vivo. Indeed, Ptpn23+/− loss predisposes mice to sporadic lung adenoma, B cell lymphoma, and promotes Myc-driven lymphoma onset, dissemination, and aggressiveness. Ptpn23+/−-derived tumors exhibit an unaltered remaining allele and maintain 50% of HD-PTP expression. Consistent with the role of HD-PTP in attenuation of integrin recycling, cell migration, and invasion, hemizygous Ptpn23+/− loss increases integrin β1-dependent B cell lymphoma survival and dissemination. Finally, we reveal frequent PTPN23 deletion and downregulation in human tumors that correlates with poor survival. Altogether, we establish HD-PTP/PTPN23 as a prominent haploinsufficient tumor suppressor gene preventing tumor progression through control of integrin trafficking
The effect of hydra mutations on HD-START domain genes in Arabidopsis thaliana
No full textThe study of sterol defective mutants of Arabidopsis thaliana has provided an invaluable opportunity to investigate the importance of sterols in plant development. The hydra mutants in particular - seedling lethal mutations - exhibit great phenotypic variation, leading to the supposition that sterols have a far more complex role in plant development than previously anticipated. It has been postulated that some sterol molecules are directly involved in the regulation of gene transcription during plant development. The binding of some sterols to START domains (sterol binding domains) found in some mammalian proteins has been noted, and it is possible that plant transcription factors containing START domains could be localised to the nucleus by the binding o f specific sterols. This hypothesis may be tested by creating HD-START::GFP fusion proteins to act as a reporter, permitting the subcellular localisation o f the produced protein to be viewed using confocal scanning laser microscopy. In order to determine if the expression of START domain transcription factors is itselfregulated by sterols, independent of possible roles for sterols in their localization to the nucleus, the comparative steady state transcription levels of five HD-START domain transcription factors were studied by real-time RT-PCR. A comparison of hydra mutant mRNA levels to their wild type counterparts was carried out to determine whether there is a requirement for sterols in the regulation o f the tested genes. Although the results do appear to suggest this to be the case, the data and the conclusions require further validation
A Perfect Tidal Storm: HD 104067 Planetary Architecture Creating an Incandescent World
No full textThe discovery of planetary systems beyond the solar system has revealed a diversity of architectures, most of which differ significantly from our system. The initial detection of an exoplanet is often followed by subsequent discoveries within the same system as observations continue, measurement precision is improved, or additional techniques are employed. The HD 104067 system is known to consist of a bright K-dwarf host star and a giant planet in a ?55 days period eccentric orbit. Here we report the discovery of an additional planet within the HD 104067 system, detected through the combined analysis of radial velocity (RV) data from the High Resolution Echelle Spectrometer and High Accuracy Radial velocity Planet Searcher instruments. The new planet has a mass similar to Uranus and is in an eccentric ?14 days orbit. Our injection-recovery analysis of the RV data exclude Saturn-mass and Jupiter-mass planets out to 3 au and 8 au, respectively. We further present Transiting Exoplanet Survey Satellite observations that reveal a terrestrial planet candidate (R p = 1.30 ± 0.12 R ?) in a ?2.2 days period orbit. Our dynamical analysis of the three planet model shows that the two outer planets produce significant eccentricity excitation of the inner planet, resulting in tidally induced surface temperatures as high as ?2600 K for an emissivity of unity. The terrestrial planet candidate may therefore be caught in a tidal storm, potentially resulting in its surface radiating at optical wavelengths. © 2024. The Author(s). Published by the American Astronomical Society
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Polarized disk emission from Herbig AE/BE stars observed using Gemini planet imager: HD 144432, HD 150193, HD 163296, and HD 169142
No full textThis is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.In order to look for signs of on-going planet formation in young disks, we carried out the first J-band polarized emission imaging of the Herbig Ae/Be stars HD 150193, HD 163296, and HD 169142 using
the Gemini Planet Imager (GPI), along with new H band observations of HD 144432. We confirm the complex “double ring” structure for the nearly face-on system HD 169142 first seen in H-band, finding
the outer ring to be substantially redder than the inner one in polarized intensity. Using radiative transfer modeling, we developed a physical model that explains the full spectral energy distribution (SED) and J- and H-band surface brightness profiles, suggesting that the di↵erential color of the two rings could come from reddened starlight traversing the inner wall and may not require di↵erences in grain properties. In addition, we clearly detect an elongated, o↵-center ring in HD 163296 (MWC 275), locating the scattering surface to be 18 AU above the midplane at a radial distance of 77 AU, cospatial with a ring seen at 1.3mm by ALMA linked to the CO snow line. Lastly, we report a weak tentative detection of scattered light for HD 150193 (MWC 863) and a non-detection for HD 144432; the stellar companion known for each of these targets has likely disrupted the material in the outer disk of the primary star. For HD 163296 and HD 169142, the prominent outer rings we detect could be evidence for giant planet formation in the outer disk or a manifestation of large-scale dust growth processes possibly related to snow-line chemistry.Exeter’s STFC Consolidated Grant (ST/J001627/1). SK acknowledges support from an STFC Rutherford Fellowship
(ST/J004030/1) and a European Research Council (ERC) Starting Grant (Grant agreement No 639889).
This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of
the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology,
funded by the National Aeronautics and Space Administration and the National Science Foundation. Based on
observations obtained at the Gemini Observatory (programs GS-2014A-SV-412, GS-2015A-Q-49), which is operated
by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on
behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council
(Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnologa e Innovacin Productiva (Argentina), and Ministrio da
Cincia, Tecnologia e Inovao (Brazil)
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