Thermoplastic rubberlike material produced at low cost

Thermoplastic rubberlike material is prepared by blending a copolymer of ethylene and vinyl acetate with asphalt and a petroleum distillate. This low cost material is easily molded or extruded and is compatible with a variety of fillers

Thermoplastic rubber comprising ethylene-vinyl acetate copolymer, asphalt and fluxing oil

A thermoplastic rubber is made from a mixture of between about 10 percent and about 50 percent of asphalt, between about 5 percent and about 30 percent fluxing oil, and between about 35 percent and about 70 percent of a copolymer of polyethylene and vinyl acetate

Cold solid propellant motor has stop-restart capability

Solid propellant rocket is kept and fired at low temperatures in launch vehicles or spacecraft. The motor is capable of developing a specific impulse comparable to that of liquid propellant motors, is started, stopped, and restarted, and is stored in space without solar radiation causing hot spots on the motor casing

Addition of solid oxidizer increases liquid fuel specific impulse

Adding soluble solid oxidizers to hydrazine and similar fuels makes them useful in low temperature bipropellant systems. These oxidizers improve the low specific impulse, high freezing point, low boiling point, and low density of the fuels

Review of solid propellants for space exploration

Solid propellants for space vehicles and spacecraft fuel application

Resistance values under transformations in regular triangular grids

In [Evans, Francis 2022; Hendel] the authors investigated resistance distance in triangular grid graphs and observed several types of asymptotic behavior. This paper extends this work by studying the initial, non-asymptotic, behavior found when equivalent circuit transformations are performed, thus reducing the rows in the triangular grid graph one row at a time. The main conjecture characterizes when edge resistance values are less than, equal to, or greater than one after reducing an arbitrary number of times a triangular grid all of whose edge resistances are identically one. A special case of the conjecture is shown. The main theorem identifies patterns of repeating edge labels arising in diagonals of a triangular grid reduced $s$ times provided the original grid had at least $4s$ rows of triangles. This paper also improves upon the notation and concepts introduced by the authors previously, and provides improved proof techniques.Comment: Intent to submit to Discrete Applied Mathematic

SMHASH: anatomy of the Orphan Stream using RR Lyrae stars

Stellar tidal streams provide an opportunity to study the motion and structure of the disrupting galaxy as well as the gravitational potential of its host. Streams around the Milky Way are especially promising as phase space positions of individual stars will be measured by ongoing or upcoming surveys. Nevertheless, it remains a challenge to accurately assess distances to stars farther than 10 kpc from the Sun, where we have the poorest knowledge of the Galaxy’s mass distribution. To address this, we present observations of 32 candidate RR Lyrae stars in the Orphan tidal stream taken as part of the Spitzer Merger History and Shape of the Galactic Halo (SMHASH) program. The extremely tight correlation between the periods, luminosities, and metallicities of RR Lyrae variable stars in the Spitzer IRAC 3.6μm band allows the determination of precise distances to individual stars; the median statistical relative distance uncertainty to each RR Lyrae star is 2.5 per cent. By fitting orbits in an example potential, we obtain an upper limit on the mass of the Milky Way interior to 60 kpc of 5.6^(+1.2)_(−1.1)×10^(11) M⊙, bringing estimates based on the Orphan Stream in line with those using other tracers. The SMHASH data also resolve the stream in line-of-sight depth, allowing a new perspective on the internal structure of the disrupted dwarf galaxy. Comparing with N–body models, we find that the progenitor had an initial dark halo mass of approximately 3.2 × 109 M⊙, placing the Orphan Stream’s progenitor amongst the classical dwarf spheroidals

ECO and RESOLVE: Galaxy Disk Growth in Environmental Context

We study the relationships between galaxy environments and galaxy properties related to disk (re)growth, considering two highly complete samples that are approximately baryonic mass limited into the high-mass dwarf galaxy regime, the Environmental COntext (ECO) catalog (data release herein) and the B-semester region of the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey. We quantify galaxy environments using both group identification and smoothed galaxy density field methods. We use by-eye and quantitative morphological classifications plus atomic gas content measurements and estimates. We find that blue early-type (E/S0) galaxies, gas-dominated galaxies, and UV-bright disk host galaxies all become distinctly more common below group halo mass ~10^11.5 Msun, implying that this low group halo mass regime may be a preferred regime for significant disk growth activity. We also find that blue early-type and blue late-type galaxies inhabit environments of similar group halo mass at fixed baryonic mass, consistent with a scenario in which blue early types can regrow late-type disks. In fact, we find that the only significant difference in the typical group halo mass inhabited by different galaxy classes is for satellite galaxies with different colors, where at fixed baryonic mass red early and late types have higher typical group halo masses than blue early and late types. More generally, we argue that the traditional morphology-environment relation (i.e., that denser environments tend to have more early types) can be largely attributed to the morphology-galaxy mass relation for centrals and the color-environment relation for satellites.Comment: 26 pages and 28 figures; v2 contains minor figure and text updates to match final published version in ApJ; ECO data table release now available at http://resolve.astro.unc.edu/pages/data.ph

The Use of a Learning Community and Online Evaluation of Utilization for SPECT Myocardial Perfusion Imaging

Resource-sensitive and quality-centered imaging begins with the selection of the appropriate patient and test. Appropriate use criteria have been developed to aid clinicians but are often not available in an easily accessible format. FOCUS (Formation of Optimal Cardiovascular Utilization Strategies), a Web-based community and quality improvement instrument, was developed to increase the feasibility of measuring and improving practice patterns based on the appropriate use criteria. The FOCUS instrument proposed to reduce inappropriate imaging by 15% in 1 year and by 50% within 3 years. Between April 2010 and December 2011, data were voluntarily collected through the FOCUS radionuclide imaging performance improvement module (PIM). Appropriateness rates were compared between phases of the PIM. For the 55 participating sites that had completed the PIM by December 2011, the proportion of inappropriate cases decreased from 10% to 5% (p < 0.0001). These preliminary data from initial participating sites suggest that through the use of a self-directed, quality improvement software and an interactive community, physicians may be able to significantly decrease the proportion of tests not meeting appropriate use criteria