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1.
PAPER OA
A finite set of equilibria for the indeterminacy of linear rational expectations models (2014)
ZBW - Deutsche Zentralbibliothek für Wirtschaftswissenschaften, Leibniz-Informationszentrum Wirtschaft Kiel und Hamburg
Publication Date: 2014-07-26
Description: This paper demonstrates the existence of a finite set of equilibria in the case of the indeterminacy of linear rational expectations models. The number of equilibria corresponds to the number of ways to select n eigenvectors among a larger set of eigenvectors related to stable eigenvalues. A finite set of equilibria is a substitute to continuous (uncountable) sets of sunspots equilibria, when the number of independent eigenvectors for each stable eigenvalue is equal to one.
Keywords: C60 ; C61 ; C62 ; E13 ; E60 ; ddc:330 ; linear rational expectations models ; sunspots ; indeterminacy ; multiple equilibria ; matrix Riccati equation
Repository Name: EconStor: OA server of the German National Library of Economics - Leibniz Information Centre for Economics
Language: eng
Type: doc-type:preprint
2.
PAPER CURRENT
Depositional facies and platform architecture of microbialite-dominated carbonate reservoirs, Ediacaran-Cambrian Ara Group, Sultanate of Oman (2014)
Publication Date: 2014-07-26
Description: Intrasalt carbonates of the Ediacaran–Cambrian Ara Group constitute a significant reservoir element of the intrasalt "stringer" play in Oman, in which dolomitic carbonates are encased in salt at depths of 3 to 7 km (1.9 to 4.3 mi). These reservoir carbonates have significant microbial influences. Although Ara Group reservoirs are mostly latest Precambrian, the models developed here may be applicable to younger microbially dominated carbonate reservoirs in basins of higher salinity when higher organisms are excluded, in lacustrine settings where calcified invertebrates are not a significant source of carbonate, or after periods of mass extinction before faunal recovery. A broad range of carbonate facies provides the context in which to understand the origin of the microbialite-dominated reservoirs developed across both ramp and rimmed shelf profiles. Major facies associations include carbonate-evaporite transition zone, deep ramp and slope, subtidal microbialites, clastic-textured carbonates, and restricted peritidal carbonates. Microbialites are subdivisible into a number of facies that all have significance in terms of understanding environmental history as well as reservoir properties, and that help in predicting the location of reservoir fairways. Microbially influenced facies include shallow subtidal thrombolites with massive clotted textures and very high initial porosities ( $$ > 50\%$$ ), shallow subtidal pustular laminites with cm-scale variability of lamina morphology, deeper subtidal crinkly laminites that show mm-scale variability of lamina morphology, and intertidal tufted laminates that show mm- to cm-scale tufted textures. Other reservoir facies are more conventional grainy carbonates including ripple cross-stratified grainstone–packstone, hummocky cross-stratified grainstone–packstone, flat pebble conglomerate, ooid and intraclast grainstone–packstone, and Cloudina grainstone–packstone. These facies are almost invariably dolomitized and all have moderate to excellent reservoir quality. These facies comprise carbonate platforms, broken up during salt tectonics, that range up to 160 m (525 ft) in thickness and extended laterally, prior to halokinesis, for tens to over 50 km (31 mi). The distribution of reservoir facies follows sequence stratigraphic predictions, with microbialites occurring in every accommodation profile. Late highstand and early transgressive systems tracts favor greater lateral extent of thrombolite build-ups, whereas later transgressive to early highstand system tracts favor greater lateral discontinuity and compartmentalization of buildup reservoir facies. Pustular laminites occur in close association with thrombolite buildups but form laterally extensive sheets in late transgressive to late highstand periods. Crinkly laminites form during late transgressive to early highstand systems tracts and may represent maximum flooding intervals when the flux of carbonate sediment was greatly reduced allowing pelagically derived organics to accumulate.
Print ISSN: 0149-1423
Electronic ISSN: 0149-1423
Topics: Geosciences
3.
PAPER CURRENT
Meteoric diagenesis and fluid-rock interaction in the Middle Permian Capitan backreef: Yates Formation, Slaughter Canyon, New Mexico (2014)
Publication Date: 2014-07-26
Description: This study examines the geochemical record of diagenesis in the Middle Permian Yates shelf, exposed in Slaughter Canyon, New Mexico. This diagenetic history significantly modified lithologies, depositional fabrics, and pore systems. Early diagenesis was dominated during sea level highstands by marine cementation and reflux dolomitization, and during sea level lowstands by meteoric cementation and stabilization—the focus of this study. This early diagenesis variably overprinted primary marine isotopic signatures, potentially leading to erroneous chemostratigraphic correlations or paleoclimate reconstructions. Four correlative sections through one m-scale cycle were analyzed for their $${{\updelta }}^{13}\mathrm{C}$$ and $${{\updelta }}^{18}\mathrm{O}$$ values. They show significant (2–4) $${{\updelta }}^{13}\mathrm{C}$$ and $${{\updelta }}^{18}\mathrm{O}$$ variability in coeval, texturally well-preserved calcites. The $${{\updelta }}^{13}\mathrm{C}$$ and $${{\updelta }}^{18}\mathrm{O}$$ values of marine cements, brachiopods, bulk carbonate, micritic matrix, and the first generation of meteoric spar (from high to low values) delineate an "inverted J curve," indicating the variable alteration of components by diagenetic fluids. Numerical models indicate that the observed stable isotope trend is most consistent with diagenetic alteration in a partially closed system by meteoric fluids mixed with a progressively diminishing contribution of recycled marine waters. In the Yates shelf, marine cements provide a more robust primary isotopic record than micritic matrix; however, neither preserves primary seawater isotopic values. Furthermore, common criteria used to diagenetically screen samples proved inadequate (e.g., textural preservation, staining, luminescence, depletion near sequence boundaries). Instead, diagenetic resetting is resolved by analyzing multiple, closely spaced, independently correlated sections, and by delineating trends between primary and later diagenetic components in populations of isotopic data.
Print ISSN: 0149-1423
Electronic ISSN: 0149-1423
Topics: Geosciences
4.
PAPER CURRENT
Agricultural wetland restorations on the USA Atlantic Coastal Plain achieve diverse native wetland plant communities but differ from natural wetlands (2014)
Publication Date: 2014-07-26
Description: Publication date: 1 December 2014 Source:Agriculture, Ecosystems & Environment, Volume 197 Author(s): Metthea Yepsen , Andrew H. Baldwin , Dennis F. Whigham , Eliza McFarland , Marina LaForgia , Megan Lang Wetland restoration is globally important for offsetting effects of wetland loss and degradation but is not consistently successful. Vegetation studies provide insight into the effectiveness of restoring wetland ecosystem functions. We compared plant community composition in 47 non-tidal wetlands under different management (natural, restored, and former wetlands that had been converted to cropland) in the Atlantic Coastal Plain of the USA. As expected, drained cropland sites were dominated by conventional upland row crops, had low species richness and evenness, and were highly disturbed. Plant communities in restored sites were more like natural sites based on the percentage of species that were native and hydrophytic, plant community evenness, and floristic quality. However, natural sites were forested, while restored and drained cropland sites were primarily herbaceous. Restored sites continued to be impacted by anthropogenic disturbance compared to natural sites. Our findings demonstrate that restored wetlands in agricultural settings can develop diverse native wetland plant communities within a decade but they remain very different from natural wetlands, raising questions about restoration goals, ecosystem service tradeoffs, and our ability to restore wetlands to ecological conditions found in reference sites.
Print ISSN: 0167-8809
Electronic ISSN: 1873-2305
Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Published by Elsevier
5.
PAPER CURRENT
Publication Date: 2014-07-26
Description: ACS Sustainable Chemistry & EngineeringDOI: 10.1021/sc5001594
Electronic ISSN: 2168-0485
Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
6.
PAPER CURRENT
High-resolution sequence stratigraphy of the Upper Ordovician Montoya Group, southern New Mexico and western Texas: Outcrop analog of an unconventional chert and carbonate reservoir (2014)
Publication Date: 2014-07-26
Description: The Upper Ordovician Montoya Group crops out in southern New Mexico and westernmost Texas and records predominantly subtidal deposition on a gently dipping carbonate ramp that was subsequently almost entirely dolomitized. The Montoya Group is a third-order composite sequence composed of six regionally correlative, shallowing-upward, third-order depositional sequences (M0–M5). Sequence M0 has sandstone at its base that is overlain by skeletal packstone-grainstone. Sequence M0 occurs only locally and was likely deposited in a topographic low formed during regional development of the unconformity following El Paso Group deposition. Sequence M1, marking the initial widespread transgression over the Ellenburger unconformity, consists of sandstone updip that passes downramp into skeletal packstone. The highstand systems tract (HST) of M1 consists of a prograding skeletal grainstone that was subaerially exposed upramp. Sequence M2, which contains the second-order maximum flooding surface, has abundant subtidal cherty carbonate at its base, which shallows upward into a widespread, prograding coral packstone-grainstone in the HST. Sequence M3 also contains abundant downramp chert that passes upramp into an aggrading crinoidal shoal and farther upramp into peritidal mudstone. Sequence M4 records an extensive basinward shift in facies as peritidal burrowed and cryptalgalaminated mudstone prograded over subtidal carbonate. Sequence M5 is only locally developed downramp and consists of crinoidal grainstone with abundant evidence of subaerial exposure. A regional unconformity separates the Montoya Group from the Silurian Fusselman Dolostone or younger units. Parasequences (meter-scale cycles) recording low- to moderate-amplitude relative sea level fluctuations are ubiquituous features at individual outcrops but are difficult to correlate regionally. The abundance of syn- or early depositional chert in the subtidal facies indicates that the Montoya Group was deposited within a region of strong regional upwelling along southern Laurentia. This early formed chert was the reservoir facies in a successful Upper Ordovician gas play in Ward and Reeves Counties, Texas.
Print ISSN: 0149-1423
Electronic ISSN: 0149-1423
Topics: Geosciences
7.
PAPER CURRENT
Development of a high-throughput assay for aldosterone synthase inhibitors using high-performance liquid chromatography–tandem mass spectrometry (2014)
Publication Date: 2014-07-26
Description: Publication date: 1 October 2014 Source:Analytical Biochemistry, Volume 462 Author(s): David Yurek , Lan Yu , James Schrementi , Michael G. Bell , James McGee , Mark Kowala , Ming-shang Kuo , Jian Wang Aldosterone plays a key role in the pathogenesis of hypertension, congestive heart failure, and chronic kidney disease. Aldosterone biosynthesis involves three membrane-bound enzymes: aldosterone synthase, adrenodoxin, and adrenodoxin reductase. Here, we report the development of a mass spectrometry-based high-throughput whole cell-based assay for aldosterone synthesis. A human adrenal carcinoma cell line (H295R) overexpressing human aldosterone synthase cDNA was established. The production of aldosterone in these cells was initiated with the addition of 11-deoxycorticosterone, the immediate substrate of aldosterone synthase. An automatic liquid handler was used to gently distribute cells uniformly to well plates. The adaption of a second automated liquid handling system to extract aldosterone from the cell culture medium into organic solvent enabled the development of 96- and 384-well plate formats for this cellular assay. A high-performance liquid chromatography–tandem mass spectrometry method was established for the detection of aldosterone. Production of aldosterone was linear with time and saturable with increasing substrate concentration. The assay was highly reproducible with an overall average Z′ value=0.49. This high-throughput assay would enable high-throughput screening for inhibitors of aldosterone biosynthesis.
Print ISSN: 0003-2697
Electronic ISSN: 1096-0309
Topics: Biology , Chemistry and Pharmacology
Published by Elsevier
8.
PAPER CURRENT
Facies, stratigraphy, and evolution of a middle Ediacaran carbonate ramp: Khufai Formation, Sultanate of Oman (2014)
Publication Date: 2014-07-26
Description: The Khufai Formation is the oldest carbonate platform of the Cryogenian to lowermost Cambrian Huqf Supergroup. A stratigraphic characterization of this unit includes detailed facies descriptions, a sequence-stratigraphic interpretation, and evaluation of lateral heterogeneity and overall ramp evolution. The Khufai Formation comprises one and one-half depositional sequences with a maximum flooding interval near the base of the formation and a sequence boundary within the upper peritidal facies. Most of the deposition occurred during highstand progradation of a carbonate ramp. Facies tracts include outer-ramp and midramp mudstones and wackestones, ramp-crest grainstone shoal deposits, and extensive inner-ramp, microbially dominated peritidal deposits. Outcrops in the Oman Mountains are deep-water deposits, including turbiditic grainstone and wackestone interbedded with siliciclastic-rich siltstone and crinkly laminite. Facies patterns and parasequence composition are variable both laterally across the outcrop area and vertically through time because of a combination of ramp morphology, siliciclastic supply, and possible syndepositional faulting. The lithostratigraphic boundary between the Khufai Formation and the overlying Shuram Formation is gradational and represents significant flooding of the carbonate platform. The stratigraphic characterization presented here along with the identification of key facies and diagenetic features will help further future exploration and production of hydrocarbons from the Khufai Formation.
Print ISSN: 0149-1423
Electronic ISSN: 0149-1423
Topics: Geosciences
9.
PAPER CURRENT
A colorimetric sandwich-type assay for sensitive thrombin detection based on enzyme-linked aptamer assay (2014)
Publication Date: 2014-07-26
Description: Publication date: 1 October 2014 Source:Analytical Biochemistry, Volume 462 Author(s): Jun Hee Park , Yea Seul Cho , Sungmuk Kang , Eun Jeong Lee , Gwan-Ho Lee , Sang Soo Hah A colorimetric sandwich-type assay based on enzyme-linked aptamer assay has been developed for the fast and sensitive detection of as low as 25fM of thrombin with high linearity. Aptamer-immobilized glass was used to capture the target analyte, whereas a second aptamer, functionalized with horseradish peroxidase (HRP), was employed for the conventional 3,5,3′,5′-tetramethylbenzidine (TMB)-based colorimetric detection. Without the troublesome antibody requirement of the conventional enzyme-linked immunosorbent assay (ELISA), as low as 25fM of thrombin could be rapidly and reproducibly detected. This assay has superior, or at least equal, recovery and accuracy to that of conventional antibody-based ELISA.
Print ISSN: 0003-2697
Electronic ISSN: 1096-0309
Topics: Biology , Chemistry and Pharmacology
Published by Elsevier
10.
PAPER CURRENT
Introduction: Honoring J. Fred Read (2014)
Publication Date: 2014-07-26
Print ISSN: 0149-1423
Electronic ISSN: 0149-1423
Topics: Geosciences