Hydrology of an Evaporite Aquitard Permian Evaporite

Permian evaporite strata of the Palo Duro Basin, Texas Panhandle, are considered to have low permeabilities but are capable of some leakage. Cross-sectional and areal modeling of regional groundwater flow in the Palo Duro Basin indicates leakage from the Upper aquifer through the Evaporite aquitard that contributes approximately 30 percent of the water in the underlying Deep-Basin Brine aquifer. The regional estimate of permeability of the aquitard (˜ 10^-4 md) is in general agreement with laboratory testing of salt permeability. Oxygen and hydrogen isotopic composition and the Cl/Br ratio of the deep-basin brines also suggest leakage through the aquitard. Isotopically nonequilibrated meteoric waters are found to depths of 8,000 ft. Leakage through the aquitard may occur as either matrix or fracture flow. According to petrographic and geochemical studies of the evaporite strata, halite dissolution and minor recrystallization occurred predominantly during Permian time. Post-Permian waters may have altered the top of the Evaporite aquitard. Fracturing is prevalent in the rock strata in the basin; the greatest density of fracturing occurs in areas with tectonic deformation. The potential for leakage may be greatest in these areas.Bureau of Economic Geolog

A disk census for the nearest group of young stars: Mid-infrared observations of the TW Hydrae Association

A group of young, active stars in the vicinity of TW Hydrae has recently been identified as a possible physical association with a common origin. Given its proximity ($\sim$50 pc), age ($\sim$10 Myr) and abundance of binary systems, the TW Hya Association is ideally suited to studies of diversity and evolution of circumstellar disks. Here we present mid-infrared observations of 15 candidate members of the group, 11 of which have no previous flux measurements at wavelengths longer than 2$\mu$m. We report the discovery of a possible 10$\mu$m excess in CD -33$^{\circ}$7795, which may be due to a circumstellar disk or a faint, as yet undetected binary companion. Of the other stars, only TW Hya, HD 98800, Hen 3-600A, and HR 4796A -- all of which were detected by IRAS -- show excess thermal emission. Our 10$\mu$m flux measurements for the remaining members of the Association are consistent with photospheric emission, allowing us to rule out dusty inner disks. In light of these findings, we discuss the origin and age of the TW Hya Association as well as implications for disk evolution timescales.Comment: 10 pages and 1 PostScript figure, accepted for publication in The Astrophysical Journal Letter

Identity Reconfiguration and the Core Needs Framework: Exit Narratives among Former Far-Right Extremists

This empirical study examines intensive interview data collected from eight (N=8) former members of white supremacist organizations in order to understand the meanings of exit – that is, disengagement and deradicalization – from the extremist’s perspective.  Using a thematic analysis approach, our findings build on the distinction in the existing exit literature between push and pull factors and the process of role exit identified by Ebaugh (1988).  These push and pull factors as well as social identity, we argue, are subsumed within a complex exit process, which includes disengagement, identity deconstruction, and transgressive and transitional relationships. For some, this process culminated in an accomplished identity reconstruction and deradicalization.  Most importantly, our findings suggest that exit is linked to entry by a developmental drive that we call the participant’s core need.  The core need was the background motivator of entry, disengagement, exit, and ultimately deradicalization.  We think that this identity reconfiguration and core needs framework may help make heterogenous exit trajectories that have remained puzzling for researchers more understandable

Treatment Retention Strategies in Transition Age Youth

This study tests Motivational Interviewing as a treatment retention intervention in transition age youth to determine whether sufficient evidence can be found to justify a full scale clinical trial

Observations on the temperature regulation and water economy of the galah (Cacatua roseicapilla)

1. 1. Galahs (Cacatua roseicapilla), like many other birds, undergo controlled hyperthermia in hot environments.2. 2. Basal metabolism of galahs (271 g) at night during summer averages 0.93 cm3O2 (g-hr)-1 vs 0.90 predicted.3. 3. They can evaporatively dissipate heat at 1.4-1.7 times the rate of metabolic heat production at high ambient temperatures (Ta).4. 4. Under moderate Ta and humidity, galahs must minimally drink 7.3 g H2O/24hr. Without water they lose 2.2% body mass/24 hr. Some of these birds benefited from drinking 0.3 M NaCl.5. 5. Galahs occupy arid Australia through good powers of heat defense, some resistance to dehydrating conditions, and mobility allowing them to reach both water and food.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24081/1/0000334.pd

Mid-infrared imaging of the young binary star Hen 3-600: Evidence for a dust disk around the primary

We present high-resolution mid-infrared observations of the nearby late-type young binary system Hen 3-600. The binary, at a distance of $\sim$ 50 pc, could be a member of the TW Hydrae Association, the nearest known group of young stars, with an age of a few million years. Our images make it possible for the first time to determine which star in the pair, separated by 1.4'', harbors the mid-infrared excess detected by IRAS. In the near-infrared, where the radiation is primarily photospheric, Hen 3-600A (M3) and Hen 3-600B (M3.5) have a flux ratio of 1.6. At 4.8$\mu$m, 10.8$\mu$m, and 18.2$\mu$m, the primary becomes increasingly dominant over the secondary, suggesting that most of the circumstellar dust in the system resides around Hen 3-600A. Comparison of the spectral energy distribution (SED) of Hen 3-600A to the median SED of classical T Tauri stars suggests that its disk may be truncated by the secondary and provides tentative evidence for a central disk hole. The distribution of dust in the Hen 3-600 system may provide important clues to the formation and evolution of protoplanetary disks in close binaries.Comment: 9 pages, 2 PostScript figures, accepted for publication in The Astrophysical Journal Letter

Modeling the Mutualistic Interactions between Tubeworms and Microbial Consortia

The deep-sea vestimentiferan tubeworm Lamellibrachia luymesi forms large aggregations at hydrocarbon seeps in the Gulf of Mexico that may persist for over 250 y. Here, we present the results of a diagenetic model in which tubeworm aggregation persistence is achieved through augmentation of the supply of sulfate to hydrocarbon seep sediments. In the model, L. luymesi releases the sulfate generated by its internal, chemoautotrophic, sulfide-oxidizing symbionts through posterior root-like extensions of its body. The sulfate fuels sulfate reduction, commonly coupled to anaerobic methane oxidation and hydrocarbon degradation by bacterial–archaeal consortia. If sulfate is released by the tubeworms, sulfide generation mainly by hydrocarbon degradation is sufficient to support moderate-sized aggregations of L. luymesi for hundreds of years. The results of this model expand our concept of the potential benefits derived from complex interspecific relationships, in this case involving members of all three domains of life