LANDSAT 4 and 5: Emergency

The primary purpose of LANDSAT is to study Earth resources. Each satellite contains a Thematic Mapper (TM) and a Multispectral Scanner (MSS) imaging device plus mission unique hardware. The flight profile is presented, and information is presented in tabular form on the following topics: Deep Space Network support, frequency assignments, telemetry, command, and tracking support responsibility

Non-Newtonian Rheology of Igneous Melts at High Stresses and Strain Rates: Experimental Results for Rhyolite, Andesite, Basalt, and Nephelinite

The stress-strain rate relationships of four silicate melt compositions (high-silica rhyolite, andesite, tholeiitic basalt, and nephelinite) have been studied using the fiber elongation method. Measurements were conducted in a stress range of 10–400 MPa and a strain rate range of 10−6 to 10−3 s−1. The stress-strain rate relationships for all the melts exhibit Newtonian behavior at low strain rates, but non-Newtonian (nonlinear stress-strain rate) behavior at higher strain rates, with strain rate increasing faster than the applied stress. The decrease in calculated shear viscosity with increasing strain rate precedes brittle failure of the fiber as the applied stress approaches the tensile strength of the melt. The decrease in viscosity observed at the high strain rates of the present study ranges from 0.25 to 2.54 log10 Pa s. The shear relaxation times τ of these melts have been estimated from the low strain rate, Newtonian, shear viscosity, using the Maxwell relationship τ = η s /G ∞. Non-Newtonian shear viscosity is observed at strain rates ( ɛ ˙ = time - 1 ) equivalent to time scales that lie 3 log10 units of time above the calculated relaxation time. Brittle failure of the fibers occurs 2 log10 units of time above the relaxation time. This study illustrates that the occurrence of non-Newtonian viscous flow in geological melts can be predicted to within a log10 unit of strain rate. High-silica rhyolite melts involved in ash flow eruptions are expected to undergo a non-Newtonian phase of deformation immediately prior to brittle failure

The fluxing effect of fluorine at magmatic temperatures (600-800 °C): A scanning calorimetric study

The effect of F on the glass transition behavior of albite, diopside, and four other silicate melts has been investigated using scanning calorimetry. The addition of F to all silicate melts investigated results in a strong, nonlinear decrease of the glass transition temperature (Z' as recorded by the peak temperatures of heat capacity). The decreases observed extrapolate consistently to published fluoride glass transition temperatures. The largest Z, decrease is observed for albite-FrO-, melts (AT = 250 °C at 6 wt%F ). The effect of F is similar to that previously observed for HrO (Taniguchi, 1981). Physical properties of low-temperature silicate liquids are a valuable constraint on lowtemperature petrogenetic processes in granite and pegmatite petrogenesis. Low-temperature wiscosities can be estimated from the glass transition data. These data are combined with previously published high-temperature, concentric-cylinder viscosity data to obtain a much more complete description of the temperature dependence of viscosity for these melts. The present data, obtained on supercooled liquids close to the glass transition, are of special significance because it is at the glass transition that silicate glass structures are frozen. A separate multinuclear NMR study of glasses quenched from these experiments has shown that the predominant coordination of F in albite glass is octahedral to Al. The coordination state of F does not appear to be concentration dependent, and thus the structural origin of the nonlinear Z, decrease does not arise from such a mechanism

Characterizing Transgender Health Issues in Twitter

Although there are millions of transgender people in the world, a lack of information exists about their health issues. This issue has consequences for the medical field, which only has a nascent understanding of how to identify and meet this population's health-related needs. Social media sites like Twitter provide new opportunities for transgender people to overcome these barriers by sharing their personal health experiences. Our research employs a computational framework to collect tweets from self-identified transgender users, detect those that are health-related, and identify their information needs. This framework is significant because it provides a macro-scale perspective on an issue that lacks investigation at national or demographic levels. Our findings identified 54 distinct health-related topics that we grouped into 7 broader categories. Further, we found both linguistic and topical differences in the health-related information shared by transgender men (TM) as com-pared to transgender women (TW). These findings can help inform medical and policy-based strategies for health interventions within transgender communities. Also, our proposed approach can inform the development of computational strategies to identify the health-related information needs of other marginalized populations