Evidence for Localized High Temperature Hydrothermal Fluid Flow within the Sub-Crater Environment of the Rochechouart Impact Structure: Observations from a Polymict Breccia Dike

Hypervelocity impacts into volatilebearing terrestrial targets can initiate hydrothermal circulation for a finite period of time; evidence for this is preserved in approximately one-third of impact structures on Earth [1, 2]. Hydrothermal environments can host extremophile life, and microbial communities have been found to colonize impact craters [3, 4]. The majority of impact structures on Earth have yet to be studied in great detail; many aspects of the post-impact environment such as the extent and duration hydrothermal circulation with respect to location within the structure as well as crater diameter, target composition and external influences, (paleogeography) are not fully understood. <p></p>We present evidence for high temperature hydrothermal fluid circulation within the sub-crater environment of the highly eroded, 23km diameter, Mesozoic Rochechouart impact structure located in west-central France [5]. This evidence is a new impact lithology that was found during a recent field campaign at a collection site located approximately 7.5km north-east of the structure's center. It is a highly porous, polymict lithic impact breccia dike containing carbonate mineralization found below the transient crater floor. Secondary hydrothermal mineral assemblages are diagnostic of a range of temperatures (>100°C to low temperature diagenetic).<p></p&gt

Impact-generated hydrothermal circulation and metasomatism of the rochechouart astrobleme: mineralogy and major and trace element distribution

The energy released during a hypervelocity impact on Earth can generate high temperatures in the target rock. There are currently 170 known impact structures worldwide, of which over one-third contain fossil hydrothermal systems [1]. Results from the analysis of these hydrothermal systems have many implications for the study of the origin of life on Earth and potential thereof on Mars. Hypervelocity impacts are also of particular economic interest as they may produce, expose or concentrate high commodity resources such as hydrocarbons, precious metals and ore minerals

Impact fracturing and aqueous alteration of the CM carbonaceous chondrites

Aqueous alteration of the CM carbonaceous chondrites has produced a suite of secondary minerals, and differences between meteorites in their abundance defines a progressive alteration sequence [e.g. 1, 2]. The means by which this water gained access to the original anhydrous constituents of the meteorites is the subject of considerable debate. Studies of rock texture, mineralogy and bulk chemical composition have concluded that solutions were generated by the melting of water ice in situ, and remained essentially static as a consequence very low intergranular permeabilities [e.g. 3, 4]. By contrast, results of oxygen isotope work and modelling have suggested that the fluids moved considerable distances within the parent body [5, 6]. Given the intergranular permeability of the CMs, an extensive fracture network would be required to support such flow. Clues to how the two very different models for aqueous alteration of the CMs can be reconciled have been recently provided by Rubin [7]. He recognised a good correlation between the magnitude of impact-induced compaction of CM meteorites and their degree of aqueous processing, with the more highly deformed meteorites being more altered. Here we have asked whether compaction was accompanied by the development of fracture networks that could have provided the conduits for aqueous solutions that mediated all or some of the alteration

Community-level characteristics of high infant mortality: A tool to identify at-risk communities

Infant mortality (IM) rate is a key indicator of population health and has been gradually improving in the United States. However, it is still a public health problem among minority and low-income communities. Maternal factors explain some of the variation, but community-level factors may also be a contributor. This study examines measures to identify a set of indicators that explain variations in IM at the community-level. Data for 77 communities in a city were obtained from local health databases. We used multivariable linear regression models to examine the strength of the association between IM and maternal, population, community wealth, and social capital characteristics. Community-level IM rates ranged from 2.1 – 25.6 deaths per 1,000 live births in 2000-2002. The final model explained 75% of the variation in IM rates at the community-level (R2=0.75). The model included a high percentage of low birth weight babies, a decline in mothers who began prenatal care in the second trimester, an increase in the percentage of Hispanics, increased unemployment rates, an increase in the percentage of veterans, an increased rate of foreign-born residents, and smaller average family sizes. Social capital variables, homicide rate and vacant housing, were also significant in the final model. Identifying communities at risk for high IM rates is imperative to improve maternal and child health outcomes because of shortages in public health resources. The development of a parsimonious set of community-level indicators can assist public health practitioners in targeting their resources to prevent infant mortality in high-risk communities

Teaching Indigenous children : listening to and learning from indigenous teachers

This article is based on the findings of a qualitative case study that examined the professional experiences and career pathways of fifty current and former Australian Indigenous teachers. Here, we draw on data obtained from semi-structured interviews with the teachers to highlight their knowledge in three key areas: ‘Indigenous ways of knowing’, ‘Indigenous learners’ lives beyond the classroom’ and ‘Building relationships with Indigenous students and communities’. We suggest that Indigenous teachers can potentially play important roles as teacher educators and as mentors to non-Indigenous teachers and preservice teachers. We argue that it is important for schooling systems and teacher education to create and formalise opportunities for non-Indigenous teachers and preservice teachers to listen to, and learn from their Indigenous colleagues

Evidence for an impact-induced biosphere from the δ34S signature of sulphides in the Rochechouart impact structure, France

The highly eroded 23 km diameter Rochechouart impact structure, France, has extensive evidence for post-impact hydrothermal alteration and sulphide mineralization. The sulphides can be divided into four types on the basis of their mineralogy and host rock. They range from pyrites and chalcopyrite in the underlying coherent crystalline basement to pyrites hosted in the impactites. Sulphur isotopic results show that δ34S values vary over a wide range, from -35.8‰ to +0.4‰. The highest values, δ34S -3.7‰ to +0.4‰, are recorded in the coherent basement, and likely represent a primary terrestrial sulphur reservoir. Sulphides with the lowest values, δ34S -35.8‰ to -5.2‰, are hosted within locally brecciated and displaced parautochthonous and autochthonous impactites. Intermediate δ34S values of -10.7‰ to -1.2‰ are recorded in the semi-continuous monomict lithic breccia unit, differing between carbonate-hosted sulphides and intraclastic and clastic matrix-hosted sulphides. Such variable isotope values are consistent with a biological origin, via bacterial sulphate reduction, for sulphides in the parautochthonous and autochthonous units; these minerals formed in the shallow subsurface and are probably related to the post impact hydrothermal system. The source of the sulphate is likely to have been seawater, penecontemporaneous to the impact, as inferred from the marginal marine paleogeography of the structure. In other eroded impact craters that show evidence for impact-induced hydrothermal circulation, indirect evidence for life may be sought isotopically within late-stage (≤120°C) secondary sulphides and within the shocked and brecciated basement immediately beneath the transient crater floor

A qualitative study of enduring relationships with Alcoholics Anonymous

This study explores long term relationships with the program of Alcoholics Anonymous. Utilizing a qualitative model identified as theory-led thematic analysis, the focus is on the transfer of dependency from the substance to the program. Theory-led thematic analysis is a three-stage process of extracting causal attributions from transcripted interviews, separating the causal attributions into emergent themes, and then further dividing the emergent themes into thematic categories. This process produced the four thematic categories of Need and Commitment, Enjoyment, Connection, and AA as a Way of Living. Each thematic category indicated varying manners through which the participants tied their lives into enduring relationships with the program. Five volunteers who are active members in Alcoholics Anonymous were interviewed for this project. Three of the participants were male and two were female. Lengths of sobriety for these participants ranged from eighteen months to over fourteen years. Although three of the five participants had relationships with Alcoholics Anonymous extending past their present lengths of sobriety, each participant has been active and attending multiple meetings weekly throughout their current sobriety. The study indicates that each of the participants maintains a moderate to strong dependence on the program in order to maintain sobriety. Balance and honesty are suggested as areas for future research. Honesty with themselves and the program, and the ability to balance outside lifestyles with Alcoholics Anonymous, appear to be key factors towards the acquisition and intensity of program dependence

Critical incidents relating to high school dropout of identified young adult Black males

textThis research, a qualitative phenomenological study, identified, and analyzed critical incidents of perceptions of young adult Black male drop-outs believed to be directly related to their departure from high schools without graduating. The focus of the study was to find possible connections between school programs, policies, and practices of the senior high school level and the drop-out problem. Devised methods analyzed reported critical incidents from several perspectives within the school setting. Some cases were referenced by using cross-matrix analyses to compare and contrast patterns of happenings. What do young Black male students having “failed”, whether personally and/or by their high schools, perceive in later years, as adults, to have been critical incidents discouraging and/or alienating them from completing a program that leads to graduation? Critical incidents will focus on four questions: 1. What are there things that happened to them at school that made them want to dropout? 2. What are the varieties of critical incidents reported as those that bear some relevance to dropping out? 3. What is the in-school context reported in their critical incidents? 4. What are the given titles of dominant persons, programs or policies related to the recalled incidents? Interview respondents were tape recorded as they gave detailed descriptions of their inschool perceptions of critical incidents. The identity of respondents, school personnel and the district remained completely anonymous. Tape recorded reports were analyzed to extract critical incidents and specifics related to the research questions. Critical incidents were coded and categorized to produce themes of types of incidents. Hearing first-hand from dropouts, of a “failed” system is the first step in a process of efforts to make it widely known and to prevent such “critical incidents” from continuing to occur when high school students forfeit a diploma and full K-12 education. This study provides alterable factors with implications for school policy, teaching and leadership practices that relate to the whole child theory of learning at every stage and level. This research supports the “whole child” concept of cultural sensitivity, diverse learning and multiculturalism. It contributes to established basics for further research and theory on institutionalized malpractices.Educational Administratio

The synthesis of an analogue of the locust CRF-like diuretic peptide, and the biological activities of this and some C-terminal fragments.

The synthesis is described of an analogue of the locust CRF-like diuretic peptide in which methionine in positions 1,3, and 13 is replaced by isosteric methyl-homoserine residues. This analogue has been tested for biological activity on Malpighian tubules in vitro, and feeding behavior in vivo. It is highly active in stimulating fluid secretion and accumulation of cAMP in tubules, and on increasing the latency to feed and reducing meal duration. A 15 residue fragment from the C-terminus of the CRF-like peptide, Locmi-DP32–46, is fully active in the feeding assay, but has only weak ability to stimulate the accumulation of cAMP in tubules. Two smaller fragments, Locmi-DP32–37 and Locmi-DP41–46, were tested but neither had consistent biological activity in any of the assays used here. None of the peptides tested have any substantive activity in increasing cGMP in tubules

Stress and Redox-dependent Chaperone Interactions in the Endoplasmic Reticulum in Barrett's Oesophagus

Barrett’s Oesophagus (BO) is an acquired condition which alters the normal structure of the distal oesophagus. BO is important as it is the only known precursor lesion for Oesophageal Adenocarcinoma (OAC) with an annual conversion rate of approximately 0.3%. There is a strong correlation between acid-reflux and the development of BO, with patients with BO having a high incidence of bile acids in their refluxate, bile acids have been implicated in ER stress and disruption of protein folding which may be important in the transition from BO to OAC. Over-expression GPx7 has been shown to protect oesophageal cells from bile acid induced stress. However, there is evidence to suggest that GPx7 is down regulated by hypermethylation of its promoter in BO. Prdx4 also has an antioxidant role but has not been investigated fully in BO and OAC, Finally AGR2 is a member of the PDI family which has been implicated in a number of cancers and may play a role in the development of OAC. This thesis did not find any noticeable expression of GPx7 in OE cells or in tissue samples of BO and OAC. Western blotting of OE cells showed a difference in redox poise between OE19 and OE33 cells and IHC showed expression of Prdx4 is gastric-like cells in BO but none in OAC tumour cells. AGR2 did not appear to be expressed in the normal oesophagus but was present in gastric-like secretory cells in BO which appeared to remain closely associated with tumour cells in OAC. Cellular experiments showed that AGR2 forms redox dependant interactions within OE cells. Taken together this may suggest a relationship between Prdx4 and AGR2 and the transition of BO to OAC