1,183 research outputs found
Summary and evaluation of the conceptual design study of a potential early commercial MHD power plant (CSPEC)
The conceptual design study of a potential early commercial MHD power plant (CSPEC) is described and the results are summarized. Each of two contractors did a conceptual design of an approximtely 1000 MWe open-cycle MHD/steam plant with oxygen enriched combustion air preheated to an intermediate temperatue in a metallic heat exchanger. The contractors were close in their overall plant efficiency estimates but differed in their capital cost and cost of electricity estimates, primarily because of differences in balance-of-plant material, contingency, and operating and maintenance cost estimates. One contractor concluded that its MHD plant design compared favorably in cost of electricity with conventional coal-fired steam plants. The other contractor is making such a comparison as part of a follow-on study. Each contractor did a preliminary investigation of part-load performance and plant availability. The results of NASA studies investigating the effect of plant size and oxidizer preheat temperature on the performance of CSPEC-type MHD plants are also described. The efficiency of a 1000 MWe plant is about three points higher than of a 200 MWe plant. Preheating to 1600 F gives an efficiency about one and one-half points higher than preheating to 800 F for all plant sizes. For each plant size and preheat temperature there is an oxidizer enrichment level and MHD generator length that gives the highest plant efficiency
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A gradual depth-dependent change of connectivity features of supragranular pyramidal cells in rat barrel cortex
Recent experimental evidence suggests a finer genetic, structural and functional subdivision of the layers which
form a cortical column. The classical layer II/III (LII/III) of rodent neocortex integrates ascending sensory information with contextual cortical information for behavioral read-out. We systematically investigated to which extent regular-spiking supragranular pyramidal neurons, located at different depths within the cortex,
show different input-output connectivity patterns. Combining glutamate-uncaging with whole-cell recordings
and biocytin filling, we revealed a novel cellular organization of LII/III: (i) “Lower LII/III” pyramidal cells receive a very strong excitatory input from lemniscal LIV and much fewer inputs from paralemniscal LVa. They project to all layers of the home column, including a feedback projection to LIV whereas transcolumnar projections are relatively sparse. (ii) “Upper LII/III” pyramidal cells also receive their strongest input from LIV, but in addition, a very strong and dense excitatory input from LVa. They project extensively to LII/III as well as LVa and Vb of their home and neighboring columns, (iii) “Middle LII/III” pyramidal cell show an intermediate connectivity phenotype that stands in many ways in-between the features described for lower versus upper LII/III. “Lower LII/III” intracolumnarly segregates and transcolumnarly integrates lemniscal information whereas “upper LII/III” seems to integrate lemniscal with paralemniscal information. This suggests a finegrained functional subdivision of the supragranular compartment containing multiple circuits without any obvious cytoarchitectonic, other structural or functional correlate of a laminar border in rodent barrel cortex
Hourly resolved cloud modification factors in the ultraviolet
Cloud impacts on the transfer of ultraviolet (UV) radiation through the atmosphere can be assessed by using a cloud modification factor (CMF). CMF, which is based on total global solar irradiation (SOL<sub>CMF</sub>), has proved to be a solid basis to derive CMFs for the UV radiation (UV<sub>CMF</sub>). This is an advantage, because total global irradiance, the basis for SOL<sub>CMF</sub>, is frequently measured and forecasted by numerical weather prediction systems and includes all relevant effects for radiation transmission, such as cloud optical depth, different cloud layers, multiple reflection, as well as the distinct difference as to whether the solar disc is obscured by clouds or not. In the UV range clouds decrease the irradiance to a lesser extent than in the visible and infrared spectral range. Thus the relationship between CMFs for solar radiation and for UV-radiation is not straight forward, but will depend on whether, for example, the solar zenith angle (SZA) and wavelength band or action spectrum in the UV have been taken into consideration. Den Outer et al. provide a UV<sub>CMF</sub> algorithm on a daily basis, which accounts for these influences. It requires as input a daily SOL<sub>CMF</sub> and the SZA at noon. The calculation of SOL<sub>CMF</sub> uses the clear-sky algorithm of the European Solar Radiation Atlas to account for varying turbidity impacts. The algorithm's capability to derive hourly UV<sub>CMFs</sub> based on the SZA at the corresponding hour and its worldwide applicability is validated for erythemal UV using observational data retrieved from the databases of the COST-Action 726 on "Long-term changes and climatology of UV radiation over Europe" and the USDA UV-B Monitoring Program. The clear-sky part of the models has proved to be of good quality. Accumulated to daily doses it forms a tight cluster of points to the highest measured daily sums. All sky model performances for hourly resolution are shown to be comparable in accuracy with the well performing daily models of the COST-726 model intercomparison
Glycemia Determines the Effect of Type 2 Diabetes Risk Genes on Insulin Secretion
OBJECTIVE—Several single nucleotide polymorphisms (SNPs) in diabetes risk genes reduce glucose- and/or incretin-induced insulin secretion. Here, we investigated interactions between glycemia and such diabetes risk polymorphisms. RESEARCH DESIGN AND METHODS—Insulin secretion was assessed by insulinogenic index and areas under the curve of C-peptide/glucose in 1,576 subjects using an oral glucose toler-ance test (OGTT). Participants were genotyped for 10 diabetes risk SNPs associated with -cell dysfunction: rs5215 (KCNJ11), rs13266634 (SLC30A8), rs7754840 (CDKAL1), rs10811661 (CDKN2A/2B), rs10830963 (MTNR1B), rs7903146 (TCF7L2), rs10010131 (WFS1), rs7923837 (HHEX), rs151290 (KCNQ1), an
(EIN)FACH? : Komplexität, Wissen, Fortschritt und die Grenzen der Germanistik
Spätestens seit den gesellschaftlichen Modernisierungsschüben in den sechziger Jahren identifiziert auch die Germanistik Erkenntnis- und Wissenszuwachs, ja allgemeiner den "Fortschritt" ihres Fachs, mit Komplexitätserhöhung. Vor diesem Hintergrund erscheint es mir wenig plausibel, die seitdem erfolgten inneren Ausdifferenzierungen und interdisziplinären Grenzüberschreitungen als durch Identitätsverlust, Zerstreuung und Desintegration gekennzeichnete Niedergangsszenarien zu beschreiben. Die Veränderungen gehorchen der immanenten Logik germanistischer Forschung, einer "disziplinierten", auf Leistung ausgerichteten, an kooperativen Großforschungsvorhaben partizipierenden Wissensproduktion
Allele Summation of Diabetes Risk Genes Predicts Impaired Glucose Tolerance in Female and Obese Individuals
INTRODUCTION: Single nucleotide polymorphisms (SNPs) in approximately 40 genes have been associated with an increased risk for type 2 diabetes (T2D) in genome-wide association studies. It is not known whether a similar genetic impact on the risk of prediabetes (impaired glucose tolerance [IGT] or impaired fasting glycemia [IFG]) exists. METHODS: In our cohort of 1442 non-diabetic subjects of European origin (normal glucose tolerance [NGT] n = 1046, isolated IFG n = 142, isolated IGT n = 140, IFG+IGT n = 114), an impact on glucose homeostasis has been shown for 9 SNPs in previous studies in this specific cohort. We analyzed these SNPs (within or in the vicinity of the genes TCF7L2, KCNJ11, HHEX, SLC30A8, WFS1, KCNQ1, MTNR1B, FTO, PPARG) for association with prediabetes. RESULTS: The genetic risk load was significantly associated with the risk for IGT (p = 0.0006) in a model including gender, age, BMI and insulin sensitivity. To further evaluate potential confounding effects, we stratified the population on gender, BMI and insulin sensitivity. The association of the risk score with IGT was present in female participants (p = 0.008), but not in male participants. The risk score was significantly associated with IGT (p = 0.008) in subjects with a body mass index higher than 30 kg/m(2) but not in non-obese individuals. Furthermore, only in insulin resistant subjects a significant association between the genetic load and the risk for IGT (p = 0.01) was found. DISCUSSION: We found that T2D genetic risk alleles cause an increased risk for IGT. This effect was not present in male, lean and insulin sensitive subjects, suggesting a protective role of beneficial environmental factors on the genetic risk
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ICPP Tank Farm planning through 2012
Historically, liquid high-level waste (HLW) generated at the Idaho Chemical Processing Plant has been stored in the Tank Farm after which it is calcined with the calcine being stored in stainless steel bins. Following the curtailment of spent nuclear fuel reprocessing in 1992, the HLW treatment methods were re-evaluated to establish a path forward for producing a final waste form from the liquid sodium bearing wastes (SBW) and the HLW calcine. Projections for significant improvements in waste generation, waste blending and evaporation, and calcination were incorporated into the Tank Farm modeling. This optimized modeling shows that all of the SBW can be calcined by the end of 2012 as required by the Idaho Settlement Agreement. This Tank Farm plan discusses the use of each of the eleven HLW tanks and shows that two tanks can be emptied, allowing them to be Resource Conservation and Recovery Act closed by 2006. In addition, it describes the construction of each tank and vault, gives the chemical concentrations of the contents of each tank, based on historical input and some sampling, and discusses the regulatory drivers important to Tank Farm operation. It also discusses new waste generation, the computer model used for the Tank Farm planning, the operating schedule for each tank, and the schedule for when each tank will be empty and closed
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