2,122 research outputs found
NASA Lidar system support and MOPA technology demonstration
A series of lidar design and technology demonstration tasks in support of a CO2 lidar program is discussed. The first of these tasks is discussed in Section VI of this report under the heading of NASA Optical Lidar Design and it consists of detailed recommendations for the layout of a CO2 Doppler lidar incorporating then existing NASA optical components and mounts. The second phase of this work consisted of the design, development, and delivery to NASA of a novel acousto-optic laser frequency stabilization system for use with the existing NASA ring laser transmitter. The second major task in this program encompasses the design and experimental demonstration of a master oscillator-power amplifier (MOPA) laser transmitter utilizing a commercially available laser as the amplifier. The MOPA design including the low chirp master oscillator is discussed in detail. Experimental results are given for one, two and three pass amplification. The report includes operating procedures for the MOPA system
A Medieval Catalan Horticultural Treatise, "Memòria de les maneres de les llaurons" : Introduction, Critical Edition, Translation, Notes and Glossary
The seven known witnesses to a hitherto unpublished medieval Catalan horticultural treatise, Memòria de les maneres de les llaurons, are compared and analyzed. A critical edition is presented, with introduction, notes, English translation and glossary. In an appendix, a synoptic edition provides transcriptions of all accessible witnesses to this text
Star-dust geometries in galaxies: The effect of interstellar matter distributions on optical and infrared properties of late-type galaxies
The presence of substantial amounts of interstellar dust in late-type galaxies affects observable parameters such as the optical surface brightness, the color, and the ratio of far-infrared to optical luminosity of these galaxies. We conducted radiative transfer calculations for late-type galaxy environments to examine two different scenarios: (1) the effects of increasing amounts of dust in two fixed geometries with different star distributions; and (2) the effects of an evolving dust-star geometry in which the total amount of dust is held constant, for three different star distributions. The calculations were done for ten photometric bands, ranging from the far-ultraviolet to the near-infrared (K), and scattered light was included in the galactic surface brightness at each wavelength. The energy absorbed throughout these ten photometric bands was assumed to re-emerge in the far-infrared as thermal dust emission. We also considered the evolutionary contraction of a constant amount of dust relative to pre-existing star distributions
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Chemical Wastes Disposed of by Deep Well Injection and Their Subsurface Reactions
More than 8.6 billion gallons of liquid industrial waste are disposed of by deep-well injection each year (Mankin and Moffett, 1987). This constitutes more than half of the approximately 15 billion gallons of liquid hazardous waste that must be disposed. About 90 percent of these wastes are injected into deep aquifers in the Gulf Coast Region (Gordon and Bloom, 1986). In recent years, the proportion of waste managed by deep well injection has increased because of the limitations on other methods of disposal such as landfills, surface impoundments, and mixing with surface soil. Therefore, until methods of waste minimization adequately limit the production of liquid hazardous waste, deep well injection is a much-needed method for disposal.
Recent legislation limits deep well injection unless the injector demonstrates that there will be no migration of hazardous constituents from the injection zone for as long as the waste remains hazardous (Federal Register 40 FR 146). To prove that injected waste does not migrate from the vicinity of the wellbore, it must be shown that the fluid or chemical constituents in the fluid are immobile or that the hazardous material degrades to a nonhazardous form before the fluid migrates from the area. It is unlikely that fluids are immobile in deep Texas aquifers, as indicated by the large gradients in fluid potential produced around injection zones (Kreitler et al., 1988). In addition, improperly sealed abandoned wells and deep growth faults, which are both common in the Gulf Coast area, can provide unexpected pathways to the surface. Instead, it needs to be shown that the hazardous chemicals are immobilized through reactions with the sediments or are transformed into nonhazardous substances.Bureau of Economic Geolog
Lossy Multi/Hyperspectral Compression HW Implementation at high data rate
Image compression is becoming more and more important, as new multispectral and hyperspectral instruments are going to generate very high data rates due to the increased spatial and spectral resolutions. Transmitting all the acquired data to the ground segment is a serious bottleneck, and compression techniques are a feasible solution to this problem. The CCSDS has established a working group (WG) on multispectral and Hyperspectral Data Compression (MHDC), which has the purpose of standardizing compression techniques to be used onboard. The WG has already standardized a lossless compression algorithm for multispectral and hyperspectral images, and has started working on a lossy compression algorithm. The complexity of lossless compression algorithms is typically larger than that of lossy ones, leading to potentially lower throughputs. Therefore, a careful assessment is required in order to identify techniques that are able to sustain very high data rates. The increased complexity can also lead to increased resource occupancy on a hardware device such as an FPGA. Lossy compression introduces information losses in the images, and these losses must be accurately characterized, and their effect on the applications investigated. For these reasons, developing a lossy algorithm requires a more elaborate process. Under an ESA contract primed by Politecnico of Torino, TSD is currently designing an IP core for FPGA and/or ASIC implementation of a lossy compression algorithm that is being proposed for CCSDS standardization. In addition to the IP core, TSD is developing a HW platform based on the Xilinx Virtex-5 XQR5VFX130, the industry's first high performance rad-hard reconfigurable FPGA for processing-intensive for space systems. Advanced results along with details of electronic platform design will be presented in this paper
Therapeutic advances in ADPKD: the future awaits
Autosomal dominant polycystic kidney disease (ADPKD) is a heterogeneous genetic disorder included in ciliopathies, representing the fourth cause of end stage renal disease (ESRD), with an estimated prevalence between 1:1000 and 1:2500. It is mainly caused by mutations in the PKD1 and PKD2 genes encoding for polycystin 1 (PC1) and polycystin 2 (PC2), which regulate differentiation, proliferation, survival, apoptosis, and autophagy. The advances in the knowledge of multiple molecular pathways involved in the pathophysiology of ADPKD led to the development of several treatments which are currently under investigation. Recently, the widespread approval of tolvaptan and, in Italy, of long-acting release octreotide (octreotide-LAR), represents but the beginning of the new therapeutic management of ADPKD patients. Encouraging results are expected from ongoing randomized controlled trials (RCTs), which are investigating not only drugs acting on the calcium/cyclic adenosin monoposphate (cAMP) pathway, the most studied target so far, but also molecules targeting specific pathophysiological pathways (e.g. epidermal growth factor (EGF) receptor, AMP-activated protein kinase (AMPK) and KEAP1-Nrf2) and sphingolipids. Moreover, studies on animal models and cultured cells have also provided further promising therapeutic strategies based on the role of intracellular calcium, cell cycle regulation, MAPK pathway, epigenetic DNA, interstitial inflammation, and cell therapy. Thus, in a near future, tailored therapy could be the key to changing the natural history of ADPKD thanks to the vigorous efforts that are being made to implement clinical and preclinical studies in this field. Our review aimed to summarize the spectrum of drugs that are available in the clinical practice and the most promising molecules undergoing clinical, animal, and cultured cell studies. Graphical abstract: [Figure not available: see fulltext.
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