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[en] A damage test procedure was established for optical components that have large incident beam footprints. The procedure was applied on coated samples for a high-powered 1053-nm, 3-ns pulse-length laser system
[en] Although many new nuclear power plants have been brought on line in that time, resulting in a capacity of 110 plants with operating permits and another twelve in the last stages of completion, all of these plants were authorized before 1978. The fundamental reason for this moratorium in new orders was the precipitous reduction in electricity demand, arising from the OPEC embargo and Iran revolution, which created excess electric capacity throughout the United States. In fact, many nuclear and coal plants were cancelled to minimize the over capacity problem and no large base load generating units have been ordered of any kind in the past decade. So the 'moratorium' is not really unique to nuclear power. Progress, coupled with increased awareness that nuclear power is one of the keys to solving atmospheric environmental problems, will swing political and public acceptance back to being favorable. Successful progress in these matters will be of benefit to public acceptance around the world and, conversely, serious technical difficulties, particularly entailing any major incident with a nuclear power plants anywhere in the world, will adversely affect the improvement in political and public acceptance in the United States. It is vitally important, therefore, that we continue to further enhance international cooperation in nuclear power. We are pleased the Korea Electric power Corporation and the Korea Advanced Energy Research Institute are participating in EPRI development programs, and hope that cooperation will increase in the future. We're most encouraged by the formation of the World Association of Nuclear Operators, which will be initiated in Moscow next month. The nuclear electric utilities and their governments around the world, the International Atomic Energy Agency, and the Nuclear Energy Agency of OECD should be commended for their initiative in international cooperation
[en] Silver (Ag) inoculation was found to significantly reduce the average grain size of cast zinc (Zn) by up to 90%. The mechanism of such grain refinement in cast Zn was investigated through varying the addition level of this peritectic-forming solute. The reduction in grain size was sensitive to Ag content due to its large growth restriction factor. When the Ag content was over its maximum solid solubility in Zn, the in situ formed nucleation particles, with dendritic morphology (different from the previously reported faceted/spherical shape), were reproducibly observed near the grain centres in the refined alloys. These particles were determined to be pro-peritectic AgZn3 phase based on the information from the Zn–Ag phase diagram, results from thermal analysis, phase identification and chemical composition. The high potency of the in situ formed AgZn3 particles, as nucleation sites for Zn grains, was further verified by electron backscattered diffraction analysis and crystallographic calculation using the edge-to-edge matching model. A new reproducible hexagonal close packed–hexagonal close packed orientation relationship between AgZn3 particles and Zn matrix was experimentally determined for the first time. In addition, the effect of the particle size and size distribution on the microstructural refinement was also investigated. Finally, the grain refinement mechanism was elucidated in terms of the nucleation crystallography and the interdependence theory
[en] The forests play an important paper in the global cycle of the carbon. At the moment, the deforestation is responsible for approximately 1.8GtC (gigatons of carbon), 20% of the global annual emissions of carbonic gas caused by the human activity. However, it is calculated that the reforestation could retain from 50 to 150 GtC along next 50 years. Concepts related with the retention of carbon are discussed. The necessity is commented of carrying out the regulation of an international market in retention of carbon with the purpose of being able to maintain acceptable norms in the reforestation projects that are executed under this program
[en] I examine the arguments which have been given for quantum fluctuation-dissipation theorems. I distinguish between a weak form of the theorem, which is true under rather general conditions, and a strong form which requires a Langevin equation for its statement. I argue that the latter has not been reliably derived in general
[en] During the winter of 2008, daily time series of images of five 'unit-cell chequerboard' targets were acquired using a digital camera. The camera and targets were located in the Majura Valley approximately 3 km from Canberra airport. We show how the contrast between the black and white sections of the targets is related to the meteorological range (or standard visual range), and compare estimates of this quantity derived from images acquired during fog and mist conditions with those from the Vaisala FD-12 visibility meter operated by the Bureau of Meteorology at Canberra Airport. The two sets of ranges are consistent but show the variability of visibility in the patchy fog conditions that often prevail in the Majura Valley. Significant spatial variations of the light extinction coefficient were found to occur over the longest 570 m optical path sampled by the imaging system. Visual ranges could be estimated out to ten times the distance to the furthest target, or approximately 6 km, in these experiments. Image saturation of the white sections of the targets was the major limitation on the quantitative interpretation of the images. In the future, the camera images will be processed in real time so that the camera exposure can be adjusted to avoid saturation.
[en] The sensitivity of the remotely-sensed water reflectance to variations in water depth and bottom albedo is investigated using a semianalytical model and the radiative transfer numerical model HYDROLIGHT. Properties of the water column are taken from published observations made on 14 Feb 2001 in the coastal waters of Moreton Bay (southeast Queensland). The sensitivities of reflectance to depth and albedo are computed using partial derivatives derived from the semianalytical model, and with finite differences using the numerical model. These are compared for various depths and bottom conditions, and also to the instrumental resolution of the Hyperion satellite remote sensing system. Sensitivity to albedo is found to be greater than sensitivity to depth under some situations making the depth signal in reflectance ambiguous. These sensitivities are then applied to bathymetry algorithms to produce error bars for depth retrievals under variable bottom albedo conditions. This is done for both the standard algorithm that uses reflectances at 550 and 650 nm corrected for optically deep water reflectance, and a blue/green ratio algorithm intended for use over low albedo areas. In the standard algorithm variations of 10% in albedo produce errors in depth estimates of approximately 0.05m over sandy bottoms which is small compared with the 2m depth resolution required to reach the bottom in the Moreton Bay experiment. The blue/green ratio algorithm showed no skill for bathymetric mapping with this dataset.
[en] New software tools are introduced to facilitate diffraction experiments involving large numbers of crystals. While existing programs have long provided a framework for lattice indexing, Bragg spot integration, and symmetry determination, these initial data processing steps often require significant manual effort. This limits the timely availability of data analysis needed for high-throughput procedures, including the selection of the best crystals from a large sample pool, and the calculation of optimal data collection parameters to assure complete spot coverage with minimal radiation damage. To make these protocols more efficient, we developed a network of software applications and application servers, collectively known as Web-Ice. When the package is installed at a crystallography beamline, a programming interface allows the beamline control software (e.g., Blu-Ice/DCSS) to trigger data analysis automatically. Results are organized based on a list of samples that the user provides, and are examined within a Web page, accessible both locally at the beamline or remotely. Optional programming interfaces permit the user to control data acquisition through the Web browser. The system as a whole is implemented to support multiple users and multiple processors, and can be expanded to provide additional scientific functionality. Web-Ice has a distributed architecture consisting of several stand-alone software components working together via a well defined interface. Other synchrotrons or institutions may integrate selected components or the whole of Web-Ice with their own data acquisition software. Updated information about current developments may be obtained at http://smb.slac.stanford.edu/research/developments/webice
[en] Multilayer coating results are discussed for the primary and secondarymirrors of the micro-exposure tool (MET): a 0.30 NA lithographici maging system with a 200 μm x 600 μm field of view at the wafer plane, operating in the extreme ultraviolet (EUV) region at an illumination wavelength around 13.4 nm. Mo/Simultilayers were deposited by DC-magnetron sputtering on large-area, curved METcamera substrates. A velocity modulation technique was implemented to consistentlyachieve multilayer thickness profiles with added figure errors below0.1 nm rmsdemonstrating sub-diffraction-limited performance, as defined by the classical diffraction limit of Rayleigh (0.25 waves peak to valley) or Marechal (0.07 waves rms). This work is an experimental demonstration of sub-diffraction-limited multilayer coatings for high-NA EUV imaging systems, which resulted in the highest resolution microfield EUV images to date
[en] Although the Advanced Light Source (ALS) was initially conceived primarily as a low energy (1.9GeV) 3rd generation source of VUV and soft x-ray radiation it was realized very early in the development of the facility that a multipole wiggler source coupled with high quality, (brightness preserving), optics would result in a beamline whose performance across the optimal energy range (5-15keV) for macromolecular crystallography (MX) would be comparable to, or even exceed, that of many existing crystallography beamlines at higher energy facilities. Hence, starting in 1996, a suite of three beamlines, branching off a single wiggler source, was constructed, which together formed the ALS Macromolecular Crystallography Facility. From the outset this facility was designed to cater equally to the needs of both academic and industrial users with a heavy emphasis placed on the development and introduction of high throughput crystallographic tools, techniques, and facilities--such as large area CCD detectors, robotic sample handling and automounting facilities, a service crystallography program, and a tightly integrated, centralized, and highly automated beamline control environment for users. This facility was immediately successful, with the primary Multiwavelength Anomalous Diffraction beamline (5.0.2) in particular rapidly becoming one of the foremost crystallographic facilities in the US--responsible for structures such as the 70S ribosome. This success in-turn triggered enormous growth of the ALS macromolecular crystallography community and spurred the development of five additional ALS MX beamlines all utilizing the newly developed superconducting bending magnets ('superbends') as sources. However in the years since the original Sector 5.0 beamlines were built the performance demands of macromolecular crystallography users have become ever more exacting; with growing emphasis placed on studying larger complexes, more difficult structures, weakly diffracting or smaller crystals, and on more rapidly screening larger numbers of candidate crystals; all of these requirements translate directly into a pressing need for increased flux, a tighter beam focus and faster detectors. With these growing demands in mind a major program of beamline and detector upgrades was initiated in 2004 with the goal of dramatically enhancing all aspects of beamline performance. Approximately $3 million in funding from diverse sources including NIH, LBL, the ALS, and the industrial and academic members of the beamline Participating Research Team (PRT), has been employed to develop and install new high performance beamline optics and to purchase the latest generation of CCD detectors. This project, which reached fruition in early 2007, has now fulfilled all of its original goals--boosting the flux on all three beamlines by up to 20-fold--with a commensurate reduction in exposure and data acquisition times for users. The performance of the Sector 5.0 beamlines is now comparable to that of the latest generation ALS superbend beamlines and, in the case of beamline 5.0.2, even surpasses it by a considerable margin. Indeed, the present performance of this beamline is now, once again, comparable to that envisioned for many MX beamlines planned or under construction on newer or higher energy machines