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We have conducted a series of VLBI observations of the gravitational-lens images of the quasar Q0957+561 (Walsh et al., 1979), utilizing the Mark III VLBI data acquisition system (Rogers et al., 1983). The goals of our observations are to (1) map the milliarcsecond structure of the A and B images, (2) detect the predicted third image of the quasar, and (3) determine the time delay between the images. We will use these results to constrain the mass distribution of the lens and, possibly, cosmological constants.
A series of VLBI observations of the gravitational lens system 0957+561 at λ13 cm has yielded the positions of the A and B images, the relative magnification of their largest discernible radio structures, and the time variability of their smallest discernible radio structures. These observations have also allowed upper limits to be placed on the flux density of an expected third image. The positions and relative magnification of the A and B images provide new information with which to constrain models of the lens that forms the images. The detection of variations in the flux densities of the cores of A and B suggests that observations at shorter wavelengths may reveal superluminal motion, which may in turn provide a means to measure the relative time delay.
The Learning Health System Network clinical data research network includes academic medical centers, health-care systems, public health departments, and health plans, and is designed to facilitate outcomes research, pragmatic trials, comparative effectiveness research, and evaluation of population health interventions.
The Learning Health System Network is 1 of 13 clinical data research networks assembled to create, in partnership with 20 patient-powered research networks, a National Patient-Centered Clinical Research Network.
Results and Conclusions
Herein, we describe the Learning Health System Network as an emerging resource for translational research, providing details on the governance and organizational structure of the network, the key milestones of the current funding period, and challenges and opportunities for collaborative science leveraging the network.
Two broad aims drive weed science research: improved management and improved understanding of weed biology and ecology. In recent years, agricultural weed research addressing these two aims has effectively split into separate subdisciplines despite repeated calls for greater integration. Although some excellent work is being done, agricultural weed research has developed a very high level of repetitiveness, a preponderance of purely descriptive studies, and has failed to clearly articulate novel hypotheses linked to established bodies of ecological and evolutionary theory. In contrast, invasive plant research attracts a diverse cadre of nonweed scientists using invasions to explore broader and more integrated biological questions grounded in theory. We propose that although studies focused on weed management remain vitally important, agricultural weed research would benefit from deeper theoretical justification, a broader vision, and increased collaboration across diverse disciplines. To initiate change in this direction, we call for more emphasis on interdisciplinary training for weed scientists, and for focused workshops and working groups to develop specific areas of research and promote interactions among weed scientists and with the wider scientific community.
The integration of biopolymers into hybrid electronics is one of the up to date issues in view of the achievement of fully bio-compatible devices. Among ‘hot topics’ in bio-polymer research, synthetic melanin or, briefly, “melanin”, has been recently recognized as a quite intriguing macromolecule thanks to its multifunctional optoelectronic properties. To date, melanin transport properties have been mainly enlightened on pellets, while optical absorption and conductivity properties have been investigated on melanin layers deposited on quartz and indium tin oxide/glass. The unavailability of suitable procedures to improve or promote adequate self assembling of melanin layer deposition onto substrate of interest in organic and solid state electronics (hybrid) like silicon substrates, prevent interesting studies on such structures. The reason stems basically on the difference between the hydrophilic nature of the melanin and the hydrophobic one of the supports (mostly of silicon). However, our group solved this issue and was able to tailor a melanin based metal/insulator/metal and metal/insulator/silicon structures, where synthetic melanin was embedded as the insulating part. This allowed to disclose interesting features related to data storage capabilities of melanin layers deposited on indium tin oxide/glass and silicon never investigated so far. In this work we show an overview on our recent mentioned results, and particular attention is paid on structures on silicon substrates. The use of pSi and nSi substrates and measurements under different environment conditions has enabled to gain insight into ambipolar electrical transport mechanisms, still unexplored. These results constitute a first important basic insight into melanin-based bio inspired structures and represent a significant step towards their integration in several kinds of hybrid organic polymer-based devices.
Guidelines concerning early stage breast cancer do not clearly recommend tumour bed boost dose after breast conserving surgery and irradiation when the resection margins are negative. Because the number of these patients is expected to increase, we evaluated the results of our treatment scheme in which the additional tumour bed dose was omitted. One hundred consecutive individuals with ductal carcinoma in-situ or stage I or II cancer of the breast were identified for this retrospective analysis. The observed ipsilateral breast tumour recurrence and 10-year disease-free survival rates were 4% and 91% respectively. Univariate analysis indicated that triple receptor negative tumour is the most independent prognostic risk factor. In conclusion, the observed low rate of local recurrence and many long-term survivors in this study seem to legitimize the omission of the tumour bed boost dose after whole breast irradiation in women with early carcinoma of the breast and free breast conserving surgical margins.
Atomic Layer Deposition (ALD) is a gas phase deposition technique for depositing very high quality thin films with an unsurpassed conformality. The main drawback of ALD however is the very low deposition rate (~ 1 nm/min). Recently, record deposition rates for alumina of up to 1 nm/s were reached using spatial ALD, while maintaining the typical assets regarding film quality as obtained by conventional, slow ALD . This allows for ALD at high throughput numbers.
One interesting application is passivation of crystalline silicon solar cells. Applying a thin alumina layer is reported to increase solar cell efficiency and enables the use of thinner wafers, thus reducing the main cost factor . In this paper we report on the latest progress made by SoLayTec that delivered a working prototype of a system realizing full area single sided deposition of alumina on 156 x 156 mm2, mono- and multi crystalline silicon wafers for solar cell applications. The alumina layers showed excellent passivation. Based on this concept, a high-throughput ALD deposition tool is being developed targeting throughput numbers of up to 3000 wafers/hr, making ALD ready for mass production. This will bring on new opportunities in other applications.
A new solid-state embedding approach has been developed which focuses on modelling the surfaces of polar materials. The method is applied to investigate the chemisorption of pre- methanol species on the polar (000-1) surface of zincite (a major phase of zinc oxide having the wurtzite structure). Initial results include the geometries of active sites and adsorbates in different charge states.
We developed a fabrication process of regular arrays of Si nanopillars using self-formation of etching masks with metal clusters as formation nuclei. When Si substrates deposited with metal clusters are subjected to electron cyclotron plasma etching with SF6 at around -130 °C, reaction products in the plasma, SxFy, condense preferentially at the clusters, leading to the self-formation of nanoscale etching masks. As a result, Si pillars, about 10 nm in diameter and 100 nm tall, are formed with remarkably narrow size-distributions when Au clusters of 1-3 nm diameter are used. This method can be easily combined with electron beam lithography technique, which enables us to define pillar positions. Using this process, we have fabricated 2 dimensional photonic crystals (square and triangular lattices of Si nanopillars) with photonic band gaps in the visible and near infrared regions. We measured reflection spectra of the photonic crystals and observed polarization-dependent reflection bands in the wavelength range consistent with theoretical calculations.
Synchrotron photoemission measurements of the Si(2p) and N(ls) levels have been made on Si3N4 thin films grown in-situ by high temperature reaction of Si(100) with NH3. The tunability of the excitation photons allowed the mean-free-path of the emitted photoelectrons to be varied, thereby providing the capability to determine not only the types of chemical species present, but their location within the film as well. The structure of these films consists of an outer monolayer (ML) of Si atoms on top of stoichiometric Si3N4. In addition, there are a smaller number (1/2 ML) of Si atoms with intermediate oxidation states at the Si3N4/Si interface.
The speciation of radionuclides and toxic metals in wastes subjected to microbial action is important in determining the extent of stabilization in a disposal environment. As part of an ongoing study, we investigated the reduction of uranium by a Clostridium sp. using X-ray absorption near edge spectroscopy (XANES) at the National Synchrotron Light Source (NSLS) and X-ray photoelectron spectroscopy (XPS). XPS analysis of uranyl acetate containing hexavalent uranium exhibited a binding energy of 382.0eV at the U 4f7/2 peak. The sample incubated in the presence of bacteria was shifted to lower binding energy (380.6eV), confirming the reduction of U6+ to U4+ at the bacterial surface. XANES analysis, using an electron yield detector, was performed at the Mv absorption edge (3d--> 5f). The absorption peak energy of the sample exhibited a shift from 3551.1eV to 3550.1eV which is higher than uranium metal (3549.6eV) but lower than U4+ (3550.4eV). This indicates the presence of U3+ which is probably located beneath the surface within the biomass. Anaerobic bacterial treatment of wastes containing uranyl ion can result in the stabilization of uranium.