939 resultados para consistent evidence
Resumo:
Detrital zircon and metamorphic monazite ages from the Picuris Mountains, north central New Mexico, were used to confirm the depositional age of the Marquenas Formation, to document the depositional age of the Vadito Group, and to constrain the timing of metamorphism and deformation in the region. Detrital zircon 207Pb/206Pb ages were obtained with the LA-MC-ICPMS from quartzites collected from the type locality of the Marquenas Formation exposed at Cerro de las Marquenas, and from the lower Vadito Group in the southern and eastern Picuris Mountains. The Marquenas Formation sample yields 113 concordant ages including a Mesoproterozoic age population with four grains ca. 1470 Ga, a broad Paleoproterozoic age peak at 1695 Ma, and minor Archean age populations. Data confirm recent findings of Mesoproterozoic detrital zircons reported by Jones et al. (2011), and show that the Marquenas Formation is the youngest lithostratigraphic unit in the Picuris Mountains. Paleoproterozoic and Archean detrital grains in the Marquenas Formation are likely derived from local recycled Vadito Group rocks and ca. 1.75 Ga plutonic complexes, and ca. 1.46 detrital zircons were most likely derived from exposed Mesoproterozoic plutons south of the Picuris. Ninety-five concordant grains from each of two Vadito Group quartzites yield relatively identical unimodal Paleoproterozoic age distributions, with peaks at 1713-1707 Ma. Eastern exposures of quartzite mapped as Marquenas Formation yield detrital zircon age patterns and metamorphic mineral assemblages that are nearly identical to the Vadito Group. On this basis, I tentatively assigned the easternmost quartzite to the Vadito Group. Zircon grains in all samples show low U/Th ratios, welldeveloped concentric zoning, and no evidence of metamorphic overgrowth events, consistent with an igneous origin. North-directed paleocurrent indicators, such as tangential crossbeds (Soegaard & Eriksson, 1986) and other primary sedimentary structures, are preserved in the Marquenas Formation quartzite. Together with pebble-toboulder metaconglomerates in the Marquenas, these observations suggest that this formation was deposited in a braided alluvial plain environment in response to syntectonic uplift to the south of the Picuris Mountains. Metamorphic monazite from two Vadito Group quartzite samples were analyzed with an electron microprobe (EMP). Elemental compositional variation with respect to Th and Y define core and rim domains in monazite grains, and show lower concentrations of Th (1.46-1.52 wt%) and Y (0.67 wt%) in the cores, and higher concentrations of Th (1.98 wt%) and Y (1.06 wt%) in the rims. Results show that Mesoproterozoic core and rim ages from five grains overlap within uncertainty, ranging from 1395-1469 Ma with an average age of 1444 Ma. This 1.44 Ga average age is the dominant timing of metamorphic monazite growth in the region, and represents the timing of metamorphism experienced by the region. An older 1630 Ma core observed in sample CD10-12 may be interpreted as a result of low temperature metamorphism in lower Vadito Group rocks due to heat from ca. 1.65 Ga granitic intrusions. Core ages ca. 1.5 Ga are likely due to a mixing age of two different age domains during analyses. Confirmed sedimentation at 1.48-1.45 Ga and documented mid-crustal regional metamorphism in northern New Mexico ca. 1.44-1.40 are likely associated with a Mesoproterozoic orogenic event.
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Preliminary detrital zircon age distributions from Mazatzal crustal province quartzite and schist exposed in the Manzano Mountains and Pedernal Hills of central New Mexico are consistent with a mixture of detritus from Mazatzal age (ca. 1650 Ma), Yavapai age (ca. 1720 Ma.), and older sources. A quartzite sample from the Blue Springs Formation in the Manzano Mountains yielding 67 concordant grain analyses shows two dominant age peaks of 1737 Ma and 1791 Ma with a minimum peak age of 1652 Ma. Quartzite and micaceous quartzite samples from near Pedernal Peak give unimodal peak ages of ca. 1695 Ma and 1738 Ma with minimum detrital zircon ages of ca. 1625 Ma and 1680 Ma, respectively. A schist sample from the southern exposures of the Pedernal Hills area gives a unimodal peak age of 1680 Ma with a minimum age of ca. 1635 Ma. Minor amounts of older detritus (>1800 Ma) possibly reflect Trans-Hudson, Wyoming, Mojave Province, and older Archean sources and aid in locating potential source terrains for these detrital zircon. The Blue Springs Formation metarhyolite from near the top of the Proterozoic section in the Manzano Mountains yields 71 concordant grains that show a preliminary U-Pb zircon crystallization age of 1621 ¿ 5 Ma, which provides a minimum age constraint for deposition in the Manzano Mountains. Normalized probability plots from this study are similar to previously reported age distributions in the Burro and San Andres Mountains in southern New Mexico and suggest that Yavapai Province age detritus was deposited and intermingled with Mazatzal Province age detritus across much of the Mazatzal crustal province in New Mexico. This data shows that the tectonic evolution of southwestern Laurentia is associated with multiple orogenic events. Regional metamorphism and deformation in the area must postdate the Mazatzal Orogeny and ca. 1610 Ma ¿ 1620 Ma rhyolite crystallization and is attributed to the Mesoproterozoic ca. 1400 ¿ 1480 Ma Picuris Orogeny.
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Nitric oxide mediates a wide array of cellular functions in many tissues. It is generated by three known isoforms of nitric oxide synthases (NOS). Recently, the endothelial isoform, NOSIII, was shown to be abundantly expressed in the rat thyroid gland and its expression increased in goitrous glands. In this study, we analyzed whether NOSIII is expressed in human thyroid tissue and whether levels of expression vary in different states of thyroid gland function. Semiquantitative RT-PCR was used to assess variations in NOSIII gene expression in seven patients with Graves' disease, one with a TSH-receptor germline mutation and six hypothyroid patients (Hashimoto's thyroiditis). Protein expression and subcellular localization were determined by immunohistochemistry (two normal thyroids, five multinodular goiters, ten hyperthyroid patients and two hypothyroid patients). NOSIII mRNA was detected in all samples: the levels were significantly higher in tissues from hyperthyroid patients compared with euthyroid and hypothyroid patients. NOSIII immunoreactivity was detected in vascular endothelial cells, but was also found in thyroid follicular cells. In patients with Graves' disease, the immunostaining was diffusely enhanced in all follicular cells. A more intense signal was observed in toxic adenomas and in samples obtained from a patient with severe hyperthyroidism due to an activating mutation in the TSH receptor. In multinodular goiters, large follicles displayed a weak signal whereas small proliferative follicles showed intense immunoreactivity near the apical plasma membrane. In hypothyroid patients, NOSIII immunoreactivity was barely detectable. In summary, NOSIII is expressed both in endothelial cells and thyroid follicular cells. The endothelial localization of NOSIII is consistent with a role for nitric oxide in the vascular control of the thyroid. NOSIII expression in thyroid follicular cells and the variations in its immunoreactivity suggest a possible role for nitric oxide in thyrocyte function and/or growth.
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Recent evidence suggests that managers establish a positive link between management accounting system (MAS) integration and controllership effectiveness, which is fully mediated by the perceived consistency of financial language. Our paper extends this research by analyzing whether controllers have similar perceptions on MAS design. Testing a series of multi-group structural equation models, we find evidence for a preparer-user perception gap with respect to the mediating impact of a consistent financial language. Our results contribute to the still-ongoing controversial debate on MAS integration by indicating that the effectiveness of MAS design cannot be evaluated solely from an instrumental perspective independent from users’ perceptions.
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Following field observations of wild Agassiz's desert tortoises (Gopherus agassizii) with oral lesions similar to those seen in captive tortoises with herpesvirus infection, we measured the prevalence of antibodies to Testudinid herpesvirus (TeHV) 3 in wild populations of desert tortoises in California. The survey revealed 30.9% antibody prevalence. In 2009 and 2010, two wild adult male desert tortoises, with gross lesions consistent with trauma and puncture wounds, respectively, were necropsied. Tortoise 1 was from the central Mojave Desert and tortoise 2 was from the northeastern Mojave Desert. We extracted DNA from the tongue of tortoise 1 and from the tongue and nasal mucosa of tortoise 2. Sequencing of polymerase chain reaction products of the herpesviral DNA-dependent DNA polymerase gene and the UL39 gene respectively showed 100% nucleotide identity with TeHV2, which was previously detected in an ill captive desert tortoise in California. Although several cases of herpesvirus infection have been described in captive desert tortoises, our findings represent the first conclusive molecular evidence of TeHV2 infection in wild desert tortoises. The serologic findings support cross-reactivity between TeHV2 and TeHV3. Further studies to determine the ecology, prevalence, and clinical significance of this virus in tortoise populations are needed.
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This article explores societal culture as an antecedent of public service motivation. Culture can be a major factor in developing an institution-based theory of public service motivation. In the field of organization theory, culture is considered a fundamental factor for explaining organization behavior. But our review of the literature reveals that culture has not been fully integrated into public service motivation theory or carefully investigated in this research stream. This study starts to fill this gap in the literature by using institutionalism and social-identity theory to predict how the sub-national Germanic and Latin cultures of Switzerland, which are measured through the mother tongues of public employees and the regional locations of public offices, affect their levels of public service motivation. Our analysis centers on two large data sets of federal and municipal employees, and produces evidence that culture has a consistent impact on public service motivation. The results show that Swiss German public employees have a significantly higher level of public service motivation on the whole, while Swiss French public employees have a significantly lower level overall. Implications for theory development and future research are discussed.
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North temperate fish in post-glacial lakes are textbook examples for rapid parallel adaptive radiation into multiple trophic specialists within individual lakes. Speciation repeatedly proceeded along the benthic – limnetic habitat axis, and benthic – limnetic sister species diverge in the number of gill rakers. Yet, the utility of different numbers of gill rakers for consuming benthic vs. limnetic food has only very rarely been experimentally demonstrated. We bred and raised families of a benthic – limnetic species pair of whitefish under common garden conditions to test whether these species (i) show heritable differentiation in feeding efficiency on zooplankton, and (ii) whether varia- tion in feeding efficiency is predicted by variation in gill raker numbers. We used zooplankton of three different size classes to investigate prey size dependency of divergence in feeding efficiency and to investigate the effect strength of variation in the number of gill rakers. Our results show strong interspecific differences in feeding efficiency. These differences are largest when fish were tested with the smallest zooplankton. Importantly, feeding efficiency is significantly positively correlated with the number of gill rakers when using small zooplankton, also when species identity is statistically controlled for. Our results support the hypothesis that a larger number of gill rakers are of adaptive significance for feeding on zooplankton and pro- vide one of the first experimental demonstrations of trait utility of gill raker number when fish feed on zooplankton. These results are consistent with the suggested importance of divergent selection driven feeding adaptation during adaptive radiation of fish in post-glacial lakes.
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We investigated high temperature Mo isotope fractionation in a hydrous supra-subduction volcano-plutonic system (Kos, Aegean Arc, Greece) in order to address the debate on the δ98/95Mo variability of the continental crust. In this igneous system, where differentiation is interpreted to be dominated by fractional crystallization, bulk rock data from olivine basalt to dacite show δ98/95Mo ratios increasing from +0.3 to +0.6‰ along with Mo concentrations increasing from 0.8 to 4.1 μg g−1. Data for hornblende and biotite mineral separates reveal the extraction of light Mo into crystallizing silicates, with minimum partition coefficients between hornblende- silicate melt and biotite-silicate melt of 0.6 and 0.4 δ98/95Mo, respectively. Our data document significant Mo isotope fractionation at magmatic temperatures, hence, the igneous contribution to continental runoff is variable, besides probable source-related variability. Based on these results and published data an average continental δ98/95Mo of +0.3 to +0.4‰ can be derived. This signature corresponds more closely to the average of published data of dissolved Mo loads of large rivers than previous estimates and is consistent with an upper limit of δ98/95Mo = 0.4‰ of the Earth's upper crust as derived from the analysis of molybdenites.
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The frequency of large-scale heavy precipitation events in the European Alps is expected to undergo substantial changes with current climate change. Hence, knowledge about the past natural variability of floods caused by heavy precipitation constitutes important input for climate projections. We present a comprehensive Holocene (10,000 years) reconstruction of the flood frequency in the Central European Alps combining 15 lacustrine sediment records. These records provide an extensive catalog of flood deposits, which were generated by flood-induced underflows delivering terrestrial material to the lake floors. The multi-archive approach allows suppressing local weather patterns, such as thunderstorms, from the obtained climate signal. We reconstructed mainly late spring to fall events since ice cover and precipitation in form of snow in winter at high-altitude study sites do inhibit the generation of flood layers. We found that flood frequency was higher during cool periods, coinciding with lows in solar activity. In addition, flood occurrence shows periodicities that are also observed in reconstructions of solar activity from C-14 and Be-10 records (2500-3000, 900-1200, as well as of about 710, 500, 350, 208 (Suess cycle), 150, 104 and 87 (Gleissberg cycle) years). As atmospheric mechanism, we propose an expansion/shrinking of the Hadley cell with increasing/decreasing air temperature, causing dry/wet conditions in Central Europe during phases of high/low solar activity. Furthermore, differences between the flood patterns from the Northern Alps and the Southern Alps indicate changes in North Atlantic circulation. Enhanced flood occurrence in the South compared to the North suggests a pronounced southward position of the Westerlies and/or blocking over the northern North Atlantic, hence resembling a negative NAO state (most distinct from 4.2 to 2.4 kyr BP and during the Little Ice Age). South-Alpine flood activity therefore provides a qualitative record of variations in a paleo-NAO pattern during the Holocene. Additionally, increased South Alpine flood activity contrasts to low precipitation in tropical Central America (Cariaco Basin) on the Holocene and centennial time scale. This observation is consistent with a Holocene southward migration of the Atlantic circulation system, and hence of the ITCZ, driven by decreasing summer insolation in the Northern hemisphere, as well as with shorter-term fluctuations probably driven by solar activity. (C) 2013 Elsevier Ltd. All rights reserved.
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This dissertation presents structural, immunochemical and neurochemical evidence for glutamatergic retinotectal synaptic transmission, augmenting and extending previous physiological and anatomical studies. The evidence is especially striking when the laminar patterns of ($\sp3$H) L-glutamate receptor binding, ($\sp3$H) L-glutamate high affinity uptake (HAU) and glutamate immunoreactivity (GLIR) of the dorsal tectum are compared. All show high activity in the tectal SGFS, with a peak in the most superficial laminae of SGFS followed by dip in the b-c region, and a second broad peak in deeper SGFS. Uptake and immunoreactivity bear a stronger resemblance to one another than either does to receptor binding, consistent with the fact that HAU and GLIR are localized in the same structures: glutamatergic terminals, intrinsic cell bodies and their processes. Receptor binding, as attested by the lack of enucleation effects, is a marker of postsynaptic receptors. In summary, these results are consistent with the hypothesis that most of the retinal projection to the optic tectum is glutamatergic: (1) A glutamate/aspartate HAU system exists in the superficial laminae, and it is dependent upon an intact retinal input, as shown developmentally and by retinal ablation; (2) Glutamate-like immunoreactivity appears in retinorecipient tectal regions (partially responsive to enucleation), in cell bodies of retinal ganglion cells and displaced ganglion cells, and in a non-tectal ganglion cell projection, the ectomammilary nucleus; (3) Sodium-independent glutamate receptor binding (which remains unchanged by enucleation) is most intense in the retinorecipient regions of the tectum and the ectomammilary nucleus. This binding is pharmacologically typical of a CNS sensory structure, being dominated by the quisqualate/kainate receptor subclass. Thus, as with other sensory systems, a portion of the retinotectal projection has been shown to include glutamatergic afferents with the distribution and properties expected of the primary projection ^
Resumo:
Von Hippel-Lindau (VHL) disease is an autosomal dominant disorder characterized by the development of retinal and central nervous system hemangioblastoma, renal cell carcinoma (RCC), pheochromocytoma and pancreatic islet cell tumors (PICT). The VHL gene maps to chromosome 3p25 and has been shown to be mutated in 57% of sporadic cases of RCC, implicating VHL in the genesis of RCC. We report a multigeneration VHL kindred in which four affected female siblings developed PICT at early ages. Analysis of the three coding exons of the VHL gene in this family revealed a single, missense mutation in codon 238. Inheritance of the 238 mutation has been reported to correlate with a 62% risk of pheochromocytoma development. In this kindred, all affected individuals carried the mutation as well as one additional sibling who showed no evidence of disease. Clinical screening of this individual indicated small ($<$1 cm) pancreatic and kidney tumors. Results suggest that inheritance of the codon 238 mutation does not correlate with early onset pheochromocytoma. Rather, the only individual in the pedigree with pheochromocytoma was the proband's mother who developed bilateral pheochromocytoma at the age of 62. Thus, the VHL codon 238 mutation may predispose to late onset pheochromocytoma in this family; however, it does not explain the preponderance of PICT in the third generation since this mutation has not been reported to increase the risk of developing pancreatic lesions. This suggests that inheritance of the codon 238 mutation and subsequent somatic inactivation of the wild type allele of the VHL gene may not be sufficient to explain the initiation and subsequent progression to malignancy in VHL-associated neoplasms. Since the two tumor types that most frequently progress to malignancy are RCC and PICT, we asked whether loss of heterozygosity (LOH) could be detected proximal to the VHL gene on chromosome 3 in distinct regions of 3p previously implicated by LOH and cytogenetic studies to contain tumor suppressor loci for RCC. LOH was performed on high molecular weight DNA isolated from peripheral blood and frozen tumor tissue of family members using microsatellite markers spanning 3p. Results indicated LOH for all informative 3p loci in tumor tissue from affected individuals with PICT. LOH was detected along the entire length of the chromosome arm and included the proximal region of 3p13-14.2 implicated in the hereditary form of renal cell carcinoma.^ If 3p LOH were a critical event in pancreatic islet cell tumorigenesis, then it should be expected that LOH in sporadic islet cell tumors would also be observed. We expanded LOH studies to include sporadic cases of PICT. Consistent LOH was observed on 3p with a highest frequency LOH in the region 3p21.2. This is the first evidence for an association between chromosome 3 loci and pancreatic islet cell tumorigenesis. (Abstract shortened by UMI.) ^
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OBJECTIVES This study sought to determine whether high intestinal cholesterol absorption represents a cardiovascular risk factor and to link ABCG8 and ABO variants to cardiovascular disease (CVD). BACKGROUND Plant sterol-enriched functional foods are widely used for cholesterol lowering. Their regular intake yields a 2-fold increase in circulating plant sterol levels that equally represent markers of cholesterol absorption. Variants in ABCG8 and ABO have been associated with circulating plant sterol levels and CVD, thereby suggesting atherogenic effects of plant sterols or of cholesterol uptake. METHODS The cholestanol-to-cholesterol ratio (CR) was used as an estimate of cholesterol absorption because it is independent of plant sterols. First, we investigated the associations of 6 single nucleotide polymorphisms in ABCG8 and ABO with CR in the LURIC (LUdwisghafen RIsk and Cardiovascular health study) and the YFS (Young Finns Study) cohorts. Second, we conducted a systematic review and meta-analysis to investigate whether CR might be related to CVD. RESULTS In LURIC, the minor alleles of rs4245791 and rs4299376 and the major alleles of rs41360247, rs6576629, and rs4953023 of the ABCG8 gene and the minor allele of rs657152 of the ABO gene were significantly associated with higher CR. Consistent results were obtained for rs4245791, rs4299376, rs6576629, and rs4953023 in YFS. The meta-analysis, including 6 studies and 4,362 individuals, found that CR was significantly increased in individuals with CVD. CONCLUSIONS High cholesterol absorption is associated with risk alleles in ABCG8 and ABO and with CVD. Harm caused by elevated cholesterol absorption rather than by plant sterols may therefore mediate the relationships of ABCG8 and ABO variants with CVD.
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We present new interpretations of deglaciation in McMurdo Sound and the western Ross Sea, with observationally based reconstructions of interactions between East and West Antarctic ice at the last glacial maximum (LGM), 16 000, 12 000, 8000 and 4000 sp. At the LGM? East Antarctic ice from Mulock Glacier split, one branch turned westward south of Ross Island but the other branch rounded Ross Island before flowing southwest into McMurdo Sound. This flow regime, constrained by an ice saddle north of Ross Island, is consistent with the reconstruction of Stuiver and others (1981a). After the LGM, grounding-line retreat was most rapid in areas with greatest water depth, especially along the Victoria Land coast. By 12 000 sp, the ice-now regime in McMurdo Sound changed to through-flowing Mulock Glacier ice, with lesser contributions from Koettlitz, Blue and Ferrar Glaciers, because the former ice saddle north of Ross Island was replaced by a dome. The modern flew regime was established similar to 4000 BP. Ice derived from high elevations on the Polar Plateau but now stranded on the McMurdo Ice Shelf, and the pattern of the Transantarctic Mountains erratics support our reconstructions of Mulock Glacier ice rounding Minna Bluff but with all ice from Skelton Glacier ablating south of the bluff. They are inconsistent with Drewry's (1979) LGM reconstruction that includes Skelton Glacier ice in the McMurdo-Sound through-flow. Drewry's (1979) model closely approximates our results for 12 000-4000 BP. Ice-sheet modeling holds promise for determining whether deglaciation proceeded by grounding-line retreat of an ice sheet that was largely stagnant, because it never approached equilibrium flowline profiles after the Ross Ice Shelf, grounded, or of a dynamic ice sheet with flowline profiles kept low by active ice streams that extended northward from present-day outlet glaciers after the Ross Ice Shelf grounded.
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Predicting the response of species to environmental changes is a great and on-going challenge for ecologists, and this requires a more in-depth understanding of the importance of biotic interactions and the population structuration in the landscape. Using a reciprocal transplantation experiment, we tested the response of five species to an elevational gradient. This was combined to a neighbour removal treatment to test the importance of local adaptation and biotic interactions. The trait studied was performance measured as survival and biomass. Species response varied along the elevational gradient, but with no consistent pattern. Performance of species was influenced by environmental conditions occurring locally at each site, as well as by positive or negative effects of the surrounding vegetation. Indeed, we observed a shift from competition for biomass to facilitation for survival as a response to the increase in environmental stress occurring in the different sites. Unlike previous studies pointing out an increase of stress along the elevation gradient, our results supported a stress gradient related to water availability, which was not strictly parallel to the elevational gradient. For three of our species, we observed a greater biomass production for the population coming from the site where the species was dominant (central population) compared to population sampled at the limit of the distribution (marginal population). Nevertheless, we did not observe any pattern of local adaptation that could indicate adaptation of populations to a particular habitat. Altogether, our results highlighted the great ability of plant species to cope with environmental changes, with no local adaptation and great variability in response to local conditions. Our study confirms the importance of taking into account biotic interactions and population structure occurring at local scale in the prediction of communities’ responses to global environmental changes.
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This paper explores the reaction of compensation components awarded to executive directors of UK financial institutions following the adoption of the bonus tax in December 2009. Excessive bonuses are blamed for encouraging risk taking and are regarded as one of the pull factors of the financial crisis. The British government attempted to reduce bonuses and accordingly corporate risk-taking by means of a special tax on cashbased bonuses. Using a comprehensive dataset on executive compensation we show that the introduction of the bonus tax decreased the net cash bonuses awarded to directors by about 43%, accompanied however by a simultaneous increase in other compensation components leaving both variable as well as total compensation unaffected. Hence, the incidence of the bonus tax was borne by the firms which compensated their managers for the decrease in cash-based compensation by awarding them different forms of pay. Consistent with this finding our data also suggests that firms reduced dividend pay-outs as a consequence of the bonus tax.