PARAS program: Phased array radio astronomy from space

An orbiting radio telescope is proposed which, when operated in a Very Long Baseline Interferometry (VLBLI) scheme, would allow higher (than currently available) angular resolution and dynamic range in the maps, and the ability of observing rapidly changing astronomical sources. Using a passive phases array technology, the proposed design consists of 656 hexagonal modules forming a 150 meter diameter dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data is transmitted to telemetry stations on the ground. The truss frame supporting each observatory pane is a hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and bottom triangle. Attitude control and stationkeeping functions are performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and six hydrazine arcjets, the latter supported by a nuclear reactor. The total mass of the spacecraft is 22,060 kg

Contemporaneous Trachyandesitic and Calc-alkaline Volcanism of the Huerto Andesite, San Juan Volcanic Field, Colorado, USA

Locally, voluminous andesitic volcanism both preceded and followed large eruptions of silicic ash-flow tuff from many calderas in the San Juan volcanic field. The most voluminous post-collapse lava suite of the central San Juan caldera cluster is the 28 Ma Huerto Andesite, a diverse assemblage erupted from at least 5-6 volcanic centres that were active around the southern margins of the La Garita caldera shortly after eruption of the Fish Canyon Tuff. These andesitic centres are inferred, in part, to represent eruptions of magma that ponded and differentiated within the crust below the La Garita caldera, thereby providing the thermal energy necessary for rejuvenation and remobilization of the Fish Canyon magma body. The multiple Huerto eruptive centres produced two magmatic series that differ in phenocryst mineralogy (hydrous vs anhydrous assemblages), whole-rock major and trace element chemistry and isotopic compositions. Hornblende-bearing lavas from three volcanic centres located close to the southeastern margin of the La Garita caldera (Eagle Mountain-Fourmile Creek, West Fork of the San Juan River, Table Mountain) define a high-K calc-alkaline series (57-65 wt % SiO2) that is oxidized, hydrous and sulphur rich. Trachyandesitic lavas from widely separated centres at Baldy Mountain-Red Lake (western margin), Sugarloaf Mountain (southern margin) and Ribbon Mesa (20 km east of the La Garita caldera) are mutually indistinguishable (55-61 wt % SiO2); they are characterized by higher and more variable concentrations of alkalis and many incompatible trace elements (e.g. Zr, Nb, heavy rare earth elements), and they contain anhydrous phenocryst assemblages (including olivine). These mildly alkaline magmas were less water rich and oxidized than the hornblende-bearing calc-alkaline suite. The same distinctions characterize the voluminous precaldera andesitic lavas of the Conejos Formation, indicating that these contrasting suites are long-term manifestations of San Juan volcanism. The favoured model for their origin involves contrasting ascent paths and differentiation histories through crustal columns with different thermal and density gradients. Magmas ascending into the main focus of the La Garita caldera were impeded, and they evolved at greater depths, retaining more of their primary volatile load. This model is supported by systematic differences in isotopic compositions suggestive of crust-magma interactions with contrasting lithologie

Numerical analysis concepts for balloon analysis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77240/1/AIAA-1994-511-453.pd

Project PARAS: Phased array radio astronomy from space

An orbiting radio telescope is proposed which, when operated in a very long baseline interferometry (VLBI) scheme, would allow higher than currently available angular resolution and dynamic range in the maps and the ability to observe rapidly changing astronomical sources. Using passive phased array technology, the proposed design consists of 656 hexagonal modules forming a 150-m diameter antenna dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data are transmitted to telemetry stations on the ground. The truss frame supporting each observatory panel is a novel hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and the bottom triangle. Attitude control and station keeping functions will be performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and four hydrazine arcjets, the latter supported by either a photovoltaic array or a radioisotope thermoelectric generator. The total mass of the spacecraft is about 20,500 kg

Adakitic Dacites Formed by Intracrustal Crystal Fractionation of Water-rich Parent Magmas at Nevado de Longaví Volcano (36·2°S; Andean Southern Volcanic Zone, Central Chile)

The mid-Holocene eruptive products of Nevado de Longaví volcano (36·2°S, Chile) are the only reported occurrence of adakitic volcanic rocks in the Quaternary Andean Southern Volcanic Zone (33-46°S). Dacites of this volcano are chemically distinct from other evolved magmas of the region in that they have high La/Yb (15-20) and Sr/Y (60-90) ratios and systematically lower incompatible element contents. An origin by partial melting of high-pressure crustal sources seems unlikely from isotopic and trace element considerations. Mafic enclaves quenched into one of the dacites, on the other hand, constitute plausible parental magmas. Dacites and mafic enclaves share several characteristics such as mineral chemistry, whole-rock isotope and trace element ratios, highly oxidizing conditions (NNO + 1·5 to >NNO + 2, where NNO is the nickel-nickel oxide buffer), and elevated boron contents. A two-stage mass-balance crystal fractionation model that matches both major and trace elements is proposed to explain magmatic evolution from the least evolved mafic enclave to the dacites. Amphibole is the main ferromagnesian phase in both stages of this model, in agreement with the mineralogy of the magmas. We also describe cumulate-textured xenoliths that correspond very closely to the solid assemblages predicted by the model. We conclude that Nevado de Longaví adakitic dacites are the products of polybaric fractional crystallization from exceptionally water-rich parent magmas. These basaltic magmas are inferred to be related to an exceptionally high, but transient input of slab-derived fluids released from serpentinite bodies hosted in the oceanic Mocha Fracture Zone, which projects beneath Nevado de Longaví. Fractional crystallization that is modally dominated by amphibole, with very minor garnet extraction, is a mechanism for generating adakitic magmas in cold subduction zones where a high flux of slab-derived fluids is presen

Acoustic vibration model for a composite shell with sound absorption material

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76741/1/AIAA-1996-1348-145.pd

Gastrocnemius Mass Is Lower 28 Days After Recovery From A Cycle Of Cisplatin In Mice

Platinum-based chemotherapeutic agents, such as cisplatin, are widely employed as a primary treatment modality for various cancer types. Despite their efficacy, cisplatin\u27s mechanism of action involves inducing DNA damage in cells, leading to pronounced acute and long-term side effects. One well established side effect is rapid loss in muscle mass. However, very little is known about the long-term effects of chemotherapy treatment on muscle size. PURPOSE: of this study was to analyze the long-term effects of cisplatin on muscle mass recovery. We hypothesized that cisplatin would have a negative long-term effect on muscle recovery. METHODS: 5-6 month-old CD2F1 mice were divided into two groups receiving injections of either Cisplatin (Cis) or Vehicle (Veh); n = 10 per group. A clinically relevant chemotherapy cycle was completed by a once weekly injection of 5mg/kg body weight of cisplatin for four weeks. Veh mice received an equal volume of saline. Following the cycle, mice recovered in their cage for 28 days and then hindlimb muscles were taken. Data were analyzed using independent t-test and presented as mean ± standard error. RESULTS: The gastrocnemius mass was significantly lower (p=0.008) in cisplatin-treated mice (139.20 ± 4.98) compared to the vehicle-treated group (147.50 ± 2.26). Conversely, the soleus did not show a significant difference (p=0.756) between Cis (9.90 ± 0.46) and Veh (10.10 ± 0.44) groups. Similarly, the Plantaris did not demonstrate a significant difference (p=0.950) in Cis treatment (18.65 ± 0.57) compared to Veh (18.65 ± 0.54). CONCLUSION: These data indicate a diminished ability of the gastrocnemius, the primary hindlimb flexor, to recover after a bout of cisplatin drug treatment. Further research is needed to better understand the mechanisms behind muscle specific differences and failed muscle mass recovery in the gastrocnemius

E. coli contamination of mountain springs used for drinking water and drilled well alternatives

Millions of people in developing communities drink water from springs on bedrock mountain slopes. Previous studies show E. coli causing many sampled springs on populated mountain slopes in southwest China to provide unsafe drinking water (Chitwood 2007a). Such studies are rare, but recently a reconnaissance study was initiated in a watershed in the Dominican Republic where more than 25,000 people, spread out across small communities and one town, rely on mountain springs. E. coli testing shows many of these springs to be unsafe. Water users live downslope and distant from the springs and receive spring water via pipelines. Likely, the E. coli originates from sparse livestock grazing up-slope from springs. Small wells drilled using portable rock coring machines and completed using novel continuous seals attached above the water intake zone are proposed to access safe drinking water drawn from permeable fractures tens of meters below ground, avoiding contamination near surface