Low-temperature geothermal ground water in the Hosston/Cotton Valley hydrogeologic unit, Falls County area, Texas

In the Falls County study area in east-central Texas, the Cotton Valley/Schuler Member and the overlying Hosston Sand (Late Jurassic to Early Cretaceous?) act as a single hydrogeologic unit (aquifer) that contains low-temperature geothermal ground water. The hydrogeologic unit consists of coarse- to very-fine-grained sandstone which becomes more fine-grained to the east, or basinward. Minor amounts of red and black shale are also present, and chert conglomerates become less common basinward. The unit was probably deposited as a bedload-dominated fluvial system in the western part of the study area, as shallow shelf sands or other sand-rich marginal-marine sediments in the central part of the study area, and possibly as sand-rich submarine-fan systems in the eastern part. Both the depositional history and the Balcones/Ouachita structural hinge control the hydrology of the aquifer. Where Balcones faulting interrupts the continuity of the aquifer, ground-water movement may be channelled along the faults. Transmissivity and hydraulic conductivity are enhanced along the Balcones Fault Zone as well. Where faulting is absent or less evident, transmissivity and hydraulic conductivity are controlled by net-sand thickness (depositional axes) and ground-water movement is downdip or radially toward a cone of depression centered in McLennan County. This cone of depression, which has resulted from years of ground-water withdrawal, influences ground-water movement throughout most of the meteoric part of the aquifer. In the eastern half of the study area, the ground water in the Hosston/Cotton Valley is saline and the pressure heads are much higher than in the western part of the aquifer, suggesting there is potential for updip movement of the saline ground water. Along the Mexia Fault Zone, which is approximately parallel to and east of the Balcones Fault Zone, pressure heads are somewhat lower than surrounding heads, suggesting that the Fault Zone is the locus of groundwater discharge from the Hosston/Cotton Valley, and possibly from aquifers beneath the Hosston/Cotton Valley. The Balcones/Ouachita hinge also appears to control the geothermal regime in the study area. In the west, the aquifer overlies Ouachita rocks and is relatively thin. East of the Balcones Fault Zone, where the Ouachita rocks begin to dip steeply into the basin, the aquifer thickens rapidly. These two regions correspond to areas of conductive and forced-convective heat flow, respectively. Geothermal gradients are high (40°C/km) along the Balcones Fault Zone, presumably due to conductive heat flow from the basement rocks, and are probably higher than normal along the Mexia Fault Zone to the east, where the faults may be acting as loci for upwelling ground water.Geological Science

Gauged Fermionic Q-balls

We present a new model for a non-topological soliton (NTS) that contains interacting fermions, scalar particles and a gauge field. Using a variational approach, we estimate the energy of the localized configuration, showing that it can be the lowest energy state of the system for a wide range of parameters.Comment: 5 pages, 2 figures; revised version to appear in Phys. Rev.

Stability of Neutral Fermi Balls with Multi-Flavor Fermions

A Fermi ball is a kind of non-topological soliton, which is thought to arise from the spontaneous breaking of an approximate $Z_2$ symmetry and to contribute to cold dark matter. We consider a simple model in which fermion fields with multi-flavors are coupled to a scalar field through Yukawa coupling, and examine how the number of the fermion flavors affects the stability of the Fermi ball against the fragmentation. (1)We find that the Fermi ball is stable against the fragmentation in most cases even in the lowest order thin-wall approximation. (2)We then find that in the other specific cases, the stability is marginal in the lowest order thin-wall approximation, and the next-to-leading order correction determines the stable region of the coupling constants; We examine the simplest case where the total fermion number $N_i$ and the Yukawa coupling constant $G_i$ of each flavor $i$ are common to the flavor, and find that the Fermi ball is stable in the limited region of the parameters and has the broader region for the larger number of the flavors.Comment: 10 pages, 3 eps figures, ReVTeX

Gauged Dimension Bubbles

Some of the peculiar electrodynamical effects associated with gauged ``dimension bubbles'' are presented. Such bubbles, which effectively enclose a region of 5d spacetime, can arise from a 5d theory with a compact extra dimension. Bubbles with thin domain walls can be stabilized against total collapse by the entrapment of light charged scalar bosons inside the bubble, extending the idea of a neutral dimension bubble to accommodate the case of a gauged U(1) symmetry. Using a dielectric approach to the 4d dilaton-Maxwell theory, it is seen that the bubble wall is almost totally opaque to photons, leading to a new stabilization mechanism due to trapped photons. Photon dominated bubbles very slowly shrink, resulting in a temperature increase inside the bubble. At some critical temperature, however, these bubbles explode, with a release of radiation.Comment: 14 pages, no figures; to appear in Phys.Rev.

The formation of boundary clinopyroxenes and associated glass veins in type B1 CAIs

We used focused ion beam thin section preparation and scanning transmission electron microscopy (FIB/STEM) to examine the interfacial region between spinel and host melilite for spinel grains in type B1 inclusions from the Allende and Leoville carbonaceous chondrites. Boundary clinopyroxenes decorating spinel surfaces have compositions similar to those of coarser clinopyroxenes from the same region of the inclusion, suggesting little movement after formation. Host melilite displays no anomalous compositions near the interface and late-stage minerals are not observed, suggesting that boundary pyroxenes did not form by crystallization of residual liquid. Allende spinels display either direct spinel-melilite contact or an intervening boundary clinopyroxene between the two phases. Spinel-melilite interfacial regions in a Leoville B1 are more complex, with boundary clinopyroxene, as observed in Allende, but also variable amounts of glass, secondary calcite, perovskite, and an Mg-, Al-, OH-rich and Ca-, Si-poor crystalline phase that may be a layered double hydrate. One possible scenario of formation for the glass veins is that open system alteration of melilite produced a porous, hydrated aggregate of Mg-carpholite or sudoite + aluminous diopside that was shock melted and quenched to a glass. The hydrated crystalline phase we observed may have been a shocked remnant of the precursor phase assemblage, but is more likely to have formed later by alteration of the glass. In the mantle, boundary clinopyroxenes may have been crystallized from Ti-rich liquids formed by the direct dissolution of perovskite and an associated Sc-Zr-rich phase or as a reaction product between dissolving perovskite and liquid. In the core, any perovskite and associated Ti-enriched liquids that may have originally been present disappeared before the growth of boundary clinopyroxene, and the observed boundary clinopyroxene may have nucleated and grown from the liquid, along with the larger core clinopyroxene

A Critical Examination of the X-Wind Model for Chondrule and Calcium-rich, Aluminum-rich Inclusion Formation and Radionuclide Production

Meteoritic data, especially regarding chondrules and calcium-rich, aluminum-rich inclusions (CAIs), and isotopic evidence for short-lived radionuclides (SLRs) in the solar nebula, potentially can constrain how planetary systems form. Intepretation of these data demands an astrophysical model, and the "X-wind" model of Shu et al. (1996) and collaborators has been advanced to explain the origin of chondrules, CAIs and SLRs. It posits that chondrules and CAIs were thermally processed < 0.1 AU from the protostar, then flung by a magnetocentrifugal outflow to the 2-3 AU region to be incorporated into chondrites. Here we critically examine key assumptions and predictions of the X-wind model. We find a number of internal inconsistencies: theory and observation show no solid material exists at 0.1 AU; particles at 0.1 AU cannot escape being accreted into the star; particles at 0.1 AU will collide at speeds high enough to destroy them; thermal sputtering will prevent growth of particles; and launching of particles in magnetocentrifugal outflows is not modeled, and may not be possible. We also identify a number of incorrect predictions of the X-wind model: the oxygen fugacity where CAIs form is orders of magnitude too oxidizing; chondrule cooling rates are orders of magnitude lower than those experienced by barred olivine chondrules; chondrule-matrix complementarity is not predicted; and the SLRs are not produced in their observed proportions. We conclude that the X-wind model is not relevant to chondrule and CAI formation and SLR production. We discuss more plausible models for chondrule and CAI formation and SLR production.Comment: Accepted for publication in The Astrophysical Journa

Burning Cold: Involvement of TRPA1 in Noxious Cold Sensation

Soon after its discovery ten years ago, the ion channel TRPA1 was proposed as a sensor of noxious cold. Evidence for its activation by painfully cold temperatures (below ~15° C) has been mixed, however. Some groups found that cold elicits a nonselective conductance in cells expressing TRPA1; others found no activation, or argued that activation is an indirect effect of elevated $Ca^{ 2+}$ . Sensory cells from the trigeminal and dorsal root ganglia that are activated by cold were sometimes correlated with those cells expressing TRPA1; other times not. Mice lacking TRPA1 showed behavioral defi cits for some assays of painful cold sensation, but not others. New evidence tends to support direct activation of TRPA1 by cold, and the slow and relatively weak activation of TRPA1 by cold helps reconcile some confl icting studies

Development that works, March 31, 2011

This repository item contains a single issue of the Pardee Conference Series, On March 31, 2011, more than 100 people participated in a conference titled “Development That Works,” sponsored by Boston University’s Frederick S. Pardee Center for the Study of the Longer-Range Future in collaboration with the BU Global Development program. In the pages that follow, four essays written by Boston University graduate students capture the salient points and overarching themes from the four sessions, each of which featured presentations by outstanding scholars and practitioners working in the field of development. The conference agenda and speakers’ biographies are included following the essays.The theme and the title of the conference—”Development That Works”—stemmed from the conference organizers’ desire to explore, from a groundlevel perspective, what programs, policies, and practices have been shown—or appear to have the potential—to achieve sustained, long-term advances in development in various parts of the world. The intent was not to simply showcase “success stories,” but rather to explore the larger concepts and opportunities that have resulted in development that is meaningful and sustainable over time. The presentations and discussions focused on critical assessments of why and how some programs take hold, and what can be learned from them. From the influence of global economic structures to innovative private sector programs and the need to evaluate development programs at the “granular” level, the expert panelists provided well-informed and often provocative perspectives on what is and isn’t working in development programs today, and what could work better in the future

Malaysian educative leadership : interim research findings

This article summarizes the policy context, the methodology and the interim findings of a research project intended to produce an indigenous theory of educative leadership in Malaysia. Educative leadership services were defined as the forms of leadership that help improve the quality of teaching and learning. A practical theory was needed to develop leadership considered appropriate in the Malaysian context of rapid economic and social development, national unity and Islamic revivalism. The practical outcomes of the study will include a validated diagnostic instrument that will measure the perceived extent to which school communities are receiving educative leadership services and implications for professional development, school development and management educa- tion. The findings from the first phase of the project are reported here, and specifically the forms of leadership service valued in Malaysian school communities as adjudged by exemplary principals and headteachers. They were assembled using iterative, qualita- tive and quantitative methods