Thermochemical conditions for the formation of Archean lode gold mineralization at Atlantic City-South Pass, Wyoming

Sediment-hosted gold mineralization of Archean age is found in the Wyoming Province and is geologically and geochemically more similar to the Phanerozoic turbidite-hosted or mesothermal type of gold deposit than to the more typically Archean greenstone-hosted type. Approximately 335,000 oz of gold have been produced from the Atlantic City-South Pass district from quartz veins in shear zones localized along the contacts of metaigneous rocks of the Miners Delight Amphibolite Belt with the surrounding metagreywackes;Rare earth element patterns for Miners Delight metagreywackes have strong LREE enrichments, Eu depletions, and more closely resemble post-Archean than Archean sediments. The widespread occurrence of similar metasediments throughout the Wyoming Province indicates that a significant source of evolved continental material existed during the Archean. Trace element data for metaigneous rocks of the Miners Delight Amphibolite Belt also supports the presence of thick continental crust during formation of the South Pass Supracrustal Belt;Lode gold deposits were emplaced in zones of structural competence contrast at the contacts of metaigneous rocks with the surrounding metasediments by multiple generations of CO[subscript]2-CH[subscript]4-H[subscript]2O-NaCl-CaCl[subscript]2 fluids in which phase separation occurred. Deposition occurred post-peak metamorphism. Sulfur isotope data does not indicate an equivocal source, but does suggest leaching of sulfur from the older Goldman Meadows Formation by reduced fluids. Carbon isotopes indicate an organic carbon component, probably derived from graphitic sediments of the district. Oxygen and hydrogen isotope and fluid inclusion compositional data suggest that the ore fluids were probably evolved formation waters. The most likely source of gold was leaching of the sedimentary pile. The deposits were formed in a subduction-related tectonic environment similar to that responsible for younger turbidite-hosted gold deposits such as those of southern Alaska, and in contrast to the volcanic-dominated environment of greenstone-hosted deposits where thick, evolved continental crust was lacking

Refusing to Endorse. A must Explanation for Pejoratives.

In her analysis of pejoratives, Eva Picardi rejects a too sharp separation between descriptive and expressive content. I reconstruct some of her arguments, endorsing Eva’s criticism of Williamson’s analysis of Dummett and developing a suggestion by Manuel Garcia Carpintero on a speech act analysis of pejoratives. Eva’s main concern is accounting for our instinctive refusal to endorse an assertion containing pejoratives because it suggests a picture of reality we do not share. Her stance might be further developed claiming that uses of pejoratives not only suggest, but also promote a wrong picture of reality. Our refusal to endorse implies rejecting not only a wrong picture of reality but also a call for participation to what that picture promotes

Interactive voice response system (IVRS): Data quality considerations and lessons learned during a microbicide placebo adherence trial with young men who have sex with men.

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106616/1/Interactive voice response system IVRS Data quality considerations and lessons learned during a microbicide placebo adherence trial with young men who have sex with men.pd

Helium Nova on a Very Massive White Dwarf -- A Light Curve Model of V445 Puppis (2000) Revised

V445 Pup (2000) is a unique object identified as a helium nova. Color indexes during the outburst are consistent with those of free-free emission. We present a free-free emission dominated light curve model of V445 Pup on the basis of the optically thick wind theory. Our light curve fitting shows that (1) the white dwarf (WD) mass is very massive (M_WD \gtrsim 1.35 M_\sun), and (2) a half of the accreted matter remains on the WD, both of which suggest that the increasing WD mass. Therefore, V445 Pup is a strong candidate of Type Ia supernova progenitor. The estimated distance to V445 Pup is now consistent with the recent observational suggestions, 3.5 < d < 6.5 kpc. A helium star companion is consistent with the brightness of m_v=14.5 mag just before the outburst, if it is a little bit evolved hot (\log T (K) \gtrsim 4.5) star with the mass of M_He \gtrsim 0.8 M_\sun. We then emphasize importance of observations in the near future quiescent phase after the thick circumstellar dust dissipates away, especially its color and magnitude to specify the nature of the companion star. We have also calculated helium ignition masses for helium shell flashes against various helium accretion rates and discussed the recurrence period of helium novae.Comment: 8 pages including 12 figures, to appear in Ap

Barrier potential for laser written graphitic wires in diamond

Diamond substrates supporting an internal array of conductive graphitic wires inscribed by a femtosecond pulse laser, are useful for the detection of ionising radiation in a range of applications. Various parameters involved in the laser fabrication process were investigated in this paper to understand their impact on the electrical properties of the wires. The study revealed an effect, whereby the wires exhibit insulating behaviour until a barrier potential is overcome. When high enough voltages are applied, the wires display ohmic behaviour. The magnitude of the barrier potential, which in some cases exceeds 300 V, is shown to be strongly dependent on the laser fabrication parameters. Through process optimisation, the potential barrier may be minimised and effectively removed, coinciding with reduced values of the wire resistance

Regulation of scleral cell contraction by transforming growth factor-β and stress competing roles in myopic growth

Reduced extracellular matrix accumulation in the sclera of myopic eyes leads to increased ocular extensibility and is related to reduced levels of scleral transforming growth factor-&beta; (TGF-&beta;). The current study investigated the impact of this extracellular environment on scleral cell phenotype and cellular biomechanical characteristics. Scleral cell phenotype was investigated in vivo in a mammalian model of myopia using the myofibroblast marker, &alpha;-smooth muscle actin (&alpha;-SMA). In eyes developing myopia &alpha;-SMA levels were increased, suggesting increased numbers of contractile myofibroblasts, and decreased in eyes recovering from myopia. To understand the factors regulating this change in scleral phenotype, the competing roles of TGF-&beta; and mechanical stress were investigated in scleral cells cultured in three-dimensional collagen gels. All three mammalian isoforms of TGF-&beta; altered scleral cell phenotype to produce highly contractile, &alpha;-SMA-expressing myofibroblasts (TGF-&beta;3 &gt; TGF-&beta;2 &gt; TGF-&beta;1). Exposure of cells to the reduced levels of TGF-&beta; found in the sclera in myopia produced decreased cell-mediated contraction and reduced &alpha;-SMA expression. These findings are contrary to the in vivo gene expression data. However, when cells were exposed to both the increased stress and the reduced levels of TGF-&beta; found in myopia, increased &alpha;-SMA expression was observed, replicating in vivo findings. These results show that although reduced scleral TGF-&beta; is a major contributor to the extracellular matrix remodeling in the myopic eye, it is the resulting increase in scleral stress that dominates the competing TGF-&beta; effect, inducing increased &alpha;-SMA expression and, hence, producing a larger population of contractile cells in the myopic eye

INTEGRAL observations of the Small Magellanic Cloud

The first INTEGRAL observations of the Small Magellanic Cloud (carried out in 2003) are reported in which two sources are clearly detected. The first source, SMC X-1, shows a hard X-ray eclipse and measurements of its pulse period indicate a continuation of the long-term spin-up now covering ~30 years. The second source is likely to be a high mass X-ray binary, and shows a potential periodicity of 6.8s in the IBIS lightcurve. An exact X-ray or optical counterpart cannot be designated, but a number of proposed counterparts are discussed. One of these possible counterparts shows a strong coherent optical modulation at ~2.7d, which, together with the measured hard X-ray pulse period, would lead to this INTEGRAL source being classified as the fourth known high mass Roche lobe overflow system.Comment: Accepted for publication in MNRA

Functional Analysis of the VirSR Phosphorelay from Clostridium perfringens

Toxin production in Clostridium perfringens is controlled by the VirSR two-component signal transduction system, which comprises the VirS sensor histidine kinase and the VirR response regulator. Other studies have concentrated on the elucidation of the genes controlled by this network; there is little information regarding the phosphorelay cascade that is the hallmark of such regulatory systems. In this study, we have examined each step in this cascade, beginning with autophosphorylation of VirS, followed by phosphotransfer from VirS to VirR. We also have studied the effects of gene dosage and phosphorylation in vivo. We have used random and site-directed mutagenesis to identify residues in VirS that are important for its function and have identified a region in the putative sensory domain of VirS that appeared to be essential for function. In vitro phosphorylation studies showed that VirSc, a truncated VirS protein that lacked the N-terminal sensory domain, was capable of autophosphorylation and could subsequently act as a phosphodonor for its cognate response regulator, VirR. Conserved residues of both VirS and VirR, including the D57 residue of VirR, were shown to be essential for this process. By use of Targetron technology, we were able to introduce a single copy of virR or virRD57N onto the chromosome of a virR mutant of C. perfringens. The results showed that in vivo, when virR was present in single copy, the production of wild-type levels of perfringolysin O was dependent on the presence of virS and an unaltered D57 residue in VirR. These results provide good evidence that phosphorylation is critical for VirR function

The predictive power of depression screening procedures for veterans with coronary artery disease

Depression leads to a worse outcome for patients with coronary artery disease (CAD). Thus, accurately identifying depression in CAD patients is imperative. In many veterans affairs (VA) hospitals, patients are screened for depression once a year using the patient health questionnaire (PHQ-9). Although the PHQ-9 is generally considered a specific and sensitive measure of depression, there is reason to believe that these screening procedures may miss a large number of cases of depression within CAD patients and cardiology patients more generally. The goal of this study was to provide data as to the predictive power of this depression screening procedure by (a) comparing the prevalence rate of depression identified by the PHQ-9 to known prevalence rates and (b) examining whether patients identified as “depressed” also had conditions that consistently co-occur with depression (eg, post-traumatic stress disorder [PTSD], other medical issues). Participants were 813 consecutive patients who received an angiogram in the cardiac catheterization laboratory at a large VA Medical Center. Prevalence of depression was 6.9% in the overall sample and less than 6% when the sample was restricted to CAD patients with significant stenosis. Depression was significantly associated with PTSD, smoking, and alcohol problems. However, depression was not associated with other medical problems such as diabetes, renal failure, peripheral vascular disease, or anemia. In conclusion, the low prevalence rate of depression and lack of associations with comorbid medical problems may suggest that the VA’s depression screening procedures have low sensitivity for identifying depression in CAD patients. It is recommended that clinicians treating CAD regularly screen for depression and do not rely on archival depression screens