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1

Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise  

USGS Publications Warehouse

Tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of SLR that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors, such as rising atmospheric CO2 concentration. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. Here, we present experimental evidence that plant response to elevated atmospheric [CO2] stimulates biogenic mechanisms of elevation gain in a brackish marsh. Elevated CO2 (ambient 340 ppm) accelerated soil elevation gain by 3.9 mm yr1 in this 2-year field study, an effect mediated by stimulation of below-ground plant productivity. Further, a companion greenhouse experiment revealed that the CO2 effect was enhanced under salinity and flooding conditions likely to accompany future SLR. Our results indicate that by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO2, may paradoxically aid some coastal wetlands in counterbalancing rising seas.

Langley, J.A.; McKee, K.L.; Cahoon, D.R.; Cherry, J.A.; Megonigala, J.P.

2009-01-01

2

Elevated CO2 stimulates marsh elevation gain, counterbalancing sea-level rise  

PubMed Central

Tidal wetlands experiencing increased rates of sea-level rise (SLR) must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of SLR that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors, such as rising atmospheric CO2 concentration. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. Here, we present experimental evidence that plant response to elevated atmospheric [CO2] stimulates biogenic mechanisms of elevation gain in a brackish marsh. Elevated CO2 (ambient + 340 ppm) accelerated soil elevation gain by 3.9 mm yr?1 in this 2-year field study, an effect mediated by stimulation of below-ground plant productivity. Further, a companion greenhouse experiment revealed that the CO2 effect was enhanced under salinity and flooding conditions likely to accompany future SLR. Our results indicate that by stimulating biogenic contributions to marsh elevation, increases in the greenhouse gas, CO2, may paradoxically aid some coastal wetlands in counterbalancing rising seas.

Langley, J. Adam; McKee, Karen L.; Cahoon, Donald R.; Cherry, Julia A.; Megonigal, J. Patrick

2009-01-01

3

Windmill having counterbalancing mechanism  

SciTech Connect

A windmill is disclosed having a counterbalancing mechanism which allows it to pump effectively under minimal wind velocity. The windmill includes blades which undergo rotational movement when actuated by the wind, a transmission for converting rotational movement of the blades to reciprocal motion of a pumping rod, a support structure or tower for supporting the blades, transmission, and rod, a counterbalancing mechanism functionally connected to the support structure and rod such that the weight of the rod and liquid column within the well is effectively counterbalanced, and a collar surrounding the rod and supported by the support structure to prevent vibration of the rod during reciprocation. The counterbalancing mechanism may include a pair of rods which are pivotably supported on the supporting structure of the windmill and pivotably mounted to the pumping rod. Weights are attached to the portions of the rods extending exteriorly from the supporting structure. The weights are appropriately positioned with respect to the pivot on the support structure to counterbalance the weight of the pumping rod and liquid column.

Cunningham, D. F.

1981-02-10

4

Counterbalancing in Smoking Cue Research: A Critical Analysis  

PubMed Central

Introduction: Cue exposure research has been used to examine key issues in smoking research, such as predicting relapse, testing new medications, investigating the neurobiology of nicotine dependence, and examining reactivity among smokers with comorbid psychopathologies. Determining the order that cues are presented is one of the most critical steps in the design of these investigations. It is widely assumed that cue exposure studies should counterbalance the order in which smoking and control (neutral) cues are presented. This article examines the premises underlying the use of counterbalancing in experimental research, and it evaluates the degree to which counterbalancing is appropriate in smoking cue exposure studies. Methods: We reviewed the available literature on the use of counterbalancing techniques in human smoking cue exposure research. Results: Many studies counterbalancing order of cues have not provided critical analyses to determine whether this approach was appropriate. Studies that have reported relevant data, however, suggest that order of cue presentation interacts with type of cue (smoking vs. control), which raises concerns about the utility of counterbalancing. Primarily, this concern arises from potential carryover effects, in which exposure to smoking cues affects subsequent responding to neutral cues. Conclusions: Cue type by order of cue interactions may compromise the utility of counterbalancing. Unfortunately, there is no obvious alternative that is optimal across studies. Strengths and limitations of several alternative designs are considered, and key questions are identified to advance understanding of the optimal conditions for conducting smoking cue exposure studies.

Griffin, Kasey M.; Sayers, W. Michael

2010-01-01

5

NK cell activation: distinct stimulatory pathways counterbalancing inhibitory signals  

Microsoft Academic Search

A delicate balance between positive and negative signals regulates NK cell effector function. Activation of NK cells may be initiated by the triggering of multiple adhesion or costimulatory molecules, and can be counterbalanced by inhibitory signals induced by receptors for MHC class I. A common pathway of inhibitory signaling is provided by immunoreceptor tyrosine-based inhibitory motifs (ITIMs) in the cytoplasmic

Alexander B. H Bakker; Jun Wu; Joseph H Phillips; Lewis L Lanier

2000-01-01

6

Overweight, gestational weight gain and elevated fasting plasma glucose and their association with macrosomia in chinese pregnant women.  

PubMed

To provide a current estimation of overweight, gestational weight gain(GWG), elevated fasting plasma glucose (FPG) in pregnant women in Kunshan, China and investigate their association with macrosomia using recommendations of IOM and International Association of Diabetes and Pregnancy Study Groups. We conducted a population-based retrospective study and analyzed routine data from Kunshan Maternity and Child Care Surveillance System of 27,322 women with singleton full-term birth from 2006 to 2010. The prevalence of maternal overweight at early pregnancy according to WHO BMI categories (BMI: 25.0-29.9 kg/m(2)) or the cutoffs for Chinese (BMI:24.0-27.9 kg/m(2)), elevated FPG (?5.1 mmol/L) were estimated. Proportions of women with GWG below, within and above 2009 IOM recommendations were used to evaluate the adequacy of GWG. The association between maternal overweight, GWG, elevated FPG and macrosomia was analyzed by multiple logistic regression. The prevalence of maternal overweight was 8.9 % according to WHO BMI categories and 11.9 % according to Chinese cutoffs. The rate of elevated FPG at first prenatal visit was 19.4 %. Overweight women gained, on average, 12.2 ± 5.3 or 13.0 ± 5.2 (kg) during gestation, 57.1 or 63.93 % of which had excessive weight gain above IOM recommendations (6.8-11.4 kg) according to WHO BMI categories or Chinese cutoffs, respectively. Maternal overweight, GWG and elevated FPG were positively and significantly associated with macrosomia after adjusting for maternal age and gestational weeks at delivery. Maternal overweight, excessive weight gain, elevated FPG are common in the Chinese population in Kunshan. These metabolic risk factors associated with macrosomia should be controlled under the recommendations for Chinese pregnant population. PMID:23784612

Shi, Peng; Yang, Wenhong; Yu, Qian; Zhao, Qian; Li, Chunying; Ma, Xiaoling; Jin, Lihua; Han, Xia; Zhang, Yi; Yan, Weili

2014-01-01

7

Zonisamide Prevents Olanzapine-Associated Hyperphagia, Weight Gain, and Elevated Blood Glucose in Rats  

Microsoft Academic Search

Olanzapine (OLZ), one of the second-generation atypical antipsychotics (SGAs), has shown relative advantages in patient adherence and outcomes. However, OLZ has also been associated with a higher incidence of weight gain than most other SGAs. Excessive weight gain may in turn contribute to long-term health concerns for some individuals. Zonisamide (ZNS), a medication approved in the United States as an

Nicholas M Wallingford; Puspha Sinnayah; Frank P Bymaster; Kishore M Gadde; Ranga K Krishnan; Anthony A McKinney; Ronald P Landbloom; Gary D Tollefson; Michael A Cowley

2008-01-01

8

Caffeine prevents weight gain and cognitive impairment caused by a high-fat diet while elevating hippocampal BDNF.  

PubMed

Obesity, high-fat diets, and subsequent type 2 diabetes (T2DM) are associated with cognitive impairment. Moreover, T2DM increases the risk of Alzheimer's disease (AD) and leads to abnormal elevation of brain beta-amyloid levels, one of the hallmarks of AD. The psychoactive alkaloid caffeine has been shown to have therapeutic potential in AD but the central impact of caffeine has not been well-studied in the context of a high-fat diet. Here we investigated the impact of caffeine administration on metabolism and cognitive performance, both in control rats and in rats placed on a high-fat diet. The effects of caffeine were significant: caffeine both (i) prevented the weight-gain associated with the high-fat diet and (ii) prevented cognitive impairment. Caffeine did not alter hippocampal metabolism or insulin signaling, likely because the high-fat-fed animals did not develop full-blown diabetes; however, caffeine did prevent or reverse a decrease in hippocampal brain-derived neurotrophic factor (BDNF) seen in high-fat-fed animals. These data confirm that caffeine may serve as a neuroprotective agent against cognitive impairment caused by obesity and/or a high-fat diet. Increased hippocampal BDNF following caffeine administration could explain, at least in part, the effects of caffeine on cognition and metabolism. PMID:23220362

Moy, Gregory A; McNay, Ewan C

2013-01-17

9

Do elevations in temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated silver birch seedlings?  

PubMed

Climate warming increases the risk of insect defoliation in boreal forests. Losses in photosynthetically active surfaces cause reduction in net primary productivity and often compromise carbon reserves of trees. The concurrent effects of climate change and removal of foliage on root growth responses and carbohydrate dynamics are poorly understood, especially in tree seedlings. We investigated if exposures to different combinations of elevated temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated 1-year-old silver birches (Betula pendula). We quantified nonstructural carbohydrates (insoluble starch as a storage compound; soluble sucrose, fructose, and glucose) singly and in combination in fine roots of plants under winter dormancy. Also the total mass, fine root proportion, water content, and length of roots were defined. We hypothesized that the measured properties are lower in defoliated birch seedlings that grow with ample resources than with scarce resources. On average, fertilization markedly decreased both the proportion and the carbohydrate concentrations of fine roots in all seedlings, whereas the effect of fertilization on root water content and dry mass was the opposite. However, defoliation mitigated the effect of fertilization on the root water content, as well as on the proportion of fine roots and their carbohydrate concentrations by reversing the outcomes. Elevation in temperature decreased and elevation in CO2 increased the absolute contents of total nonstructural carbohydrates, whereas fertilization alleviated both these effects. Also the root length and mass increased by CO2 elevation. This confirms that surplus carbon in birch tissues is used as a substrate for storage compounds and for cell wall synthesis. To conclude, our results indicate that some, but not all elements of climate change alter belowground carbon gain and root morphology in defoliated silver birch seedlings. PMID:24101972

Huttunen, Liisa; Saravesi, Karita; Markkola, Annamari; Niemelä, Pekka

2013-09-01

10

Do elevations in temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated silver birch seedlings?  

PubMed Central

Climate warming increases the risk of insect defoliation in boreal forests. Losses in photosynthetically active surfaces cause reduction in net primary productivity and often compromise carbon reserves of trees. The concurrent effects of climate change and removal of foliage on root growth responses and carbohydrate dynamics are poorly understood, especially in tree seedlings. We investigated if exposures to different combinations of elevated temperature, CO2, and nutrient availability modify belowground carbon gain and root morphology in artificially defoliated 1-year-old silver birches (Betula pendula). We quantified nonstructural carbohydrates (insoluble starch as a storage compound; soluble sucrose, fructose, and glucose) singly and in combination in fine roots of plants under winter dormancy. Also the total mass, fine root proportion, water content, and length of roots were defined. We hypothesized that the measured properties are lower in defoliated birch seedlings that grow with ample resources than with scarce resources. On average, fertilization markedly decreased both the proportion and the carbohydrate concentrations of fine roots in all seedlings, whereas the effect of fertilization on root water content and dry mass was the opposite. However, defoliation mitigated the effect of fertilization on the root water content, as well as on the proportion of fine roots and their carbohydrate concentrations by reversing the outcomes. Elevation in temperature decreased and elevation in CO2 increased the absolute contents of total nonstructural carbohydrates, whereas fertilization alleviated both these effects. Also the root length and mass increased by CO2 elevation. This confirms that surplus carbon in birch tissues is used as a substrate for storage compounds and for cell wall synthesis. To conclude, our results indicate that some, but not all elements of climate change alter belowground carbon gain and root morphology in defoliated silver birch seedlings.

Huttunen, Liisa; Saravesi, Karita; Markkola, Annamari; Niemela, Pekka

2013-01-01

11

Fundamentals of ionic conductivity relaxation gained from study of procaine hydrochloride and procainamide hydrochloride at ambient and elevated pressure.  

PubMed

The pharmaceuticals, procaine hydrochloride and procainamide hydrochloride, are glass-forming as well as ionically conducting materials. We have made dielectric measurements at ambient and elevated pressures to characterize the dynamics of the ion conductivity relaxation in these pharmaceuticals, and calorimetric measurements for the structural relaxation. Perhaps due to their special chemical and physical structures, novel features are found in the ionic conductivity relaxation of these pharmaceuticals. Data of conductivity relaxation in most ionic conductors when represented by the electric loss modulus usually show a single resolved peak in the electric modulus loss M(")(f) spectra. However, in procaine hydrochloride and procainamide hydrochloride we find in addition another resolved loss peak at higher frequencies over a temperature range spanning across T(g). The situation is analogous to many non-ionic glass-formers showing the presence of the structural ?-relaxation together with the Johari-Goldstein (JG) ?-relaxation. Naturally the analogy leads us to name the slower and faster processes resolved in procaine hydrochloride and procainamide hydrochloride as the primary ?-conductivity relaxation and the secondary ?-conductivity relaxation, respectively. The analogy of the ?-conductivity relaxation in procaine HCl and procainamide HCl with JG ?-relaxation in non-ionic glass-formers goes further by the finding that the ?-conductivity is strongly related to the ?-conductivity relaxation at temperatures above and below T(g). At elevated pressure but compensated by raising temperature to maintain ?-conductivity relaxation time constant, the data show invariance of the ratio between the ?- and the ?-conductivity relaxation times to changes of thermodynamic condition. This property indicates that the ?-conductivity relaxation has fundamental importance and is indispensable as the precursor of the ?-conductivity relaxation, analogous to the relation found between the Johari-Goldstein ?-relaxation and the structural ?-relaxation in non-ionic glass-forming systems. The novel features of the ionic conductivity relaxation are brought out by presenting the measurements in terms of the electric modulus or permittivity. If presented in terms of conductivity, the novel features are lost. This warns against insisting that a log-log plot of conductivity vs. frequency is optimal to reveal and interpret the dynamics of ionic conductors. PMID:22559496

Wojnarowska, Z; Swiety-Pospiech, A; Grzybowska, K; Hawelek, L; Paluch, M; Ngai, K L

2012-04-28

12

Dietary linoleic acid elevates endogenous 2-arachidonoylglycerol and anandamide in Atlantic salmon (Salmo salar L.) and mice, and induces weight gain and inflammation in mice.  

PubMed

Dietary intake of linoleic acid (LA) has increased dramatically during the twentieth century and is associated with a greater prevalence of obesity. Vegetable oils are recognised as suitable alternatives to fish oil (FO) in feed for Atlantic salmon (Salmo salar L.) but introduce high amounts of LA in the salmon fillet. The effect on fish consumers of such a replacement remains to be elucidated. Here, we investigate the effect of excessive dietary LA from soyabean oil (SO) on endocannabinoid levels in Atlantic salmon and mice, and study the metabolic effects in mice when SO replaces FO in feed for Atlantic salmon. Atlantic salmon were fed FO and SO for 6 months, and the salmon fillet was used to produce feed for mice. Male C57BL/6J mice were fed diets of 35% of energy as fat based on FO- and SO-enriched salmon for 16 weeks. We found that replacing FO with SO in feed for Atlantic salmon increased LA, arachidonic acid (AA), decreased EPA and DHA, elevated the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA), and increased TAG accumulation in the salmon liver. In mice, the SO salmon diet increased LA and AA and decreased EPA and DHA in the liver and erythrocyte phospholipids, and elevated 2-AG and AEA associated with increased feed efficiency, weight gain and adipose tissue inflammation compared with mice fed the FO salmon diet. In conclusion, excessive dietary LA elevates endocannabinoids in the liver of salmon and mice, and increases weight gain and counteracts the anti-inflammatory properties of EPA and DHA in mice. PMID:22883314

Alvheim, Anita R; Torstensen, Bente E; Lin, Yu Hong; Lillefosse, Haldis H; Lock, Erik-Jan; Madsen, Lise; Hibbeln, Joseph R; Malde, Marian K

2013-04-28

13

Dietary linoleic acid elevates endogenous 2-arachidonoylglycerol and anandamide in Atlantic salmon (Salmo salar L.) and mice, and induces weight gain and inflammation in mice  

PubMed Central

Dietary intake of linoleic acid (LA) has increased dramatically during the twentieth century and is associated with a greater prevalence of obesity. Vegetable oils are recognised as suitable alternatives to fish oil (FO) in feed for Atlantic salmon (Salmo salar L.) but introduce high amounts of LA in the salmon fillet. The effect on fish consumers of such a replacement remains to be elucidated. Here, we investigate the effect of excessive dietary LA from soyabean oil (SO) on endocannabinoid levels in Atlantic salmon and mice, and study the metabolic effects in mice when SO replaces FO in feed for Atlantic salmon. Atlantic salmon were fed FO and SO for 6 months, and the salmon fillet was used to produce feed for mice. Male C57BL/6J mice were fed diets of 35 % of energy as fat based on FO- and SO-enriched salmon for 16 weeks. We found that replacing FO with SO in feed for Atlantic salmon increased LA, arachidonic acid (AA), decreased EPA and DHA, elevated the endocannabinoids 2-arachidonoylglycerol (2-AG) and anandamide (AEA), and increased TAG accumulation in the salmon liver. In mice, the SO salmon diet increased LA and AA and decreased EPA and DHA in the liver and erythrocyte phospholipids, and elevated 2-AG and AEA associated with increased feed efficiency, weight gain and adipose tissue inflammation compared with mice fed the FO salmon diet. In conclusion, excessive dietary LA elevates endocannabinoids in the liver of salmon and mice, and increases weight gain and counteracts the anti-inflammatory properties of EPA and DHA in mice.

Alvheim, Anita R.; Torstensen, Bente E.; Lin, Yu Hong; Lillefosse, Haldis H.; Lock, Erik-Jan; Madsen, Lise; Hibbeln, Joseph R.; Malde, Marian K.

2012-01-01

14

Elevated PDGFRB gene copy number gain is prognostic for improved survival outcomes in resected malignant pleural mesothelioma.  

PubMed

PDGF/PDGFR pathway has been implicated in malignant pleural mesothelioma (MPM) carcinogenesis, and evidence suggests autocrine mechanisms of proliferation. We sought to evaluate the incidence of PDGFRB gene copy number gain (CNG) by fluorescence in situ hybridization and PDGFR pathway protein expression by immunohistochemistry (IHC) and correlate it to patient clinical outcome. Eighty-eight archived tumor blocks from resected MPM with full clinical information were used to perform IHC biomarkers (PDGFR?, PDGFR?, p-PDGFR?) and fluorescence in situ hybridization analysis of PDGFRB gene CNG. Spearman rank correlation, Wilcoxon rank-sum test, Kruskal-Wallis test, BLiP plots, and Kaplan-Meier method were used to analyze the biomarkers and correlation to clinical outcome. Several correlations between the IHC biomarkers were seen; however, none correlated to clinically relevant patient demographics or histology. In the CNG analysis, PDGFRB gene CNG in >10% of tumor cells had lower cytoplasmic p-PDGFR? (P=.029), while PDGFRB gene CNG in >40% of tumor cells had a higher cytoplasmic PDGFR? (P=.04). PDGFRB gene CNG status did not associate with patient demographics or tumor characteristics. PDGFR pathway IHC biomarkers did not associate with survival outcomes. However, patients with PDGFRB CNG >40% of tumor cells had improved relapse-free survival (HR 0.25 [95% CI 0.09-0.72], P=.0096) and improved overall survival (HR 0.32 [95% CI 0.11-0.89], P=.029). PDGFRB CNG >40% of MPM tumor cells is a potential prognostic biomarker for surgery and may identify a unique population of mesothelioma patients. Future validation of this biomarker in prospective trials is needed. From a retrospective review of archived tissue specimens from patients with resected malignant pleural mesothelioma tumors, we show that patients with PDGFRB CNG >40% of tumor cells had improved relapse-free survival (HR 0.25 [95% CI 0.09-0.72], P=.0096) and improved overall survival (HR 0.32 [95% CI 0.11-0.89], P=.029). PDGFRB CNG >40% of MPM tumor cells is a potential prognostic biomarker for surgery and may identify a unique population of mesothelioma patients. PMID:24747001

Tsao, Anne S; Harun, Nusrat; Fujimoto, Junya; Devito, Vikki; Lee, J Jack; Kuhn, Elisabetta; Mehran, Reza; Rice, David; Moran, Cesar; Hong, Waun Ki; Shen, Li; Suraokar, Milind; Wistuba, Ignacio

2014-06-01

15

Elevated CO2, nitrogen availability and marsh tolerance for sea-level rise  

NASA Astrophysics Data System (ADS)

Tidal wetlands experiencing increased rates of sea-level rise must increase rates of soil elevation gain to avoid permanent conversion to open water. The maximal rate of sea-level rise that these ecosystems can tolerate depends partly on mineral sediment deposition, but the accumulation of organic matter is equally important for many wetlands. Plant productivity drives organic matter dynamics and is sensitive to global change factors such as elevated atmospheric CO2 and nitrogen eutrophication. It remains unknown how global change will influence organic mechanisms that determine future tidal wetland viability. We manipulated atmospheric CO2 concentration and nitrogen availability (2 x 2 factorial) in a highly organic tidal marsh. Elevated CO2 (ambient + 340 ppm) accelerated soil elevation gain by 3.9 mm yr-1, an effect caused primarily by stimulating belowground plant productivity. Nitrogen additions, despite increasing aboveground productivity, tended to reverse elevation gains, perhaps by reducing root productivity and stimulating soil decomposition. Therefore, increases in the greenhouse gas, CO2, may paradoxically aid some coastal wetlands in counterbalancing rising seas, but nitrogen pollution may negate this effect regionally. These effects on the organic mechanisms of marsh elevation gain may help explain patterns marsh formation and disappearance worldwide.

Langley, J. A.; Cahoon, D. R.; Megonigal, J. P.

2008-12-01

16

Gaso-dynamic counterbalancer for pneumatically driven expander in rotary split Stirling cryocooler  

NASA Astrophysics Data System (ADS)

Numerous military thermal imagers operating under hostile environmental conditions rely on tactical rotary split Stirling cryocoolers, the pneumatically driven expanders of which are known to be the source of considerable vibration export. The cold tip temperature in such a cooler is typically stabilized by controlling the driving frequency in accordance with thermal loading and ambient temperature, leading to a frequency-swept harmonic vibration export into the optomechanical structure of the thermal imager. The active vibration cancellation systems are basically capable of suppressing such vibration, but are still quite bulky, complicated and expensive. In this paper, the authors report on the recent efforts towards developing a low cost vibration counterbalancer for a pneumatically driven expander in a rotary cryogenic cooler. In this approach, the flexurally suspended auxiliary mass - counterbalancer - is arranged to oscillate coaxially with the expander"s displacer and is driven pneumatically by the pulses of the working fluid produced by the compressor. Based on the results of analytical modeling and Sage optimization, the counterbalancer was designed and manufactured as an integral part of such an expander. The full-scale experimentation has shown essential cancellation of vibration export within the working frequency range from 30 to 60Hz without noticeable effect on cryocooler performance.

Riabzev, Sergey V.; Veprik, Alexander M.; Pundak, Nachman; Pratt, Uri; Vilenchik, Herman

2004-08-01

17

Dynamic counterbalancing the single-piston linear compressor of a Stirling cryogenic cooler  

NASA Astrophysics Data System (ADS)

Low vibration Stirling cryocoolers often rely on dual-piston linear compressors, the known disadvantages of which, as compared to their single-piston rivals, are: low reliability, increased power consumption, price, bulk, sensitivity to external vibration and g-forces. However, because of the inherently low level of vibration export, as required in numerous vibration sensitive electronic and electro-optic applications, the dual-piston approach has become prevalent in today's industrial practice. The authors report on the novel approach to the passive control of a fundamental component of a vibration export from a single-piston compressor down to the levels typical for the actively controlled dual-piston rival. The technique relies on the newly proposed principle of dynamic counterbalancing, where an auxiliary movable mass is flexibly attached to a movable piston assembly and to the stationary compressor casing using auxiliary mechanical springs. The proper design of such a "spring-mass-spring" counterbalancer yields zero vibration export at minimum electrical power and current consumed by the motor. Based on the theoretical analysis, the design of the single-piston compressor of 1 W@77 K Ricor model K529N Stirling cryocooler was enhanced by adding such a counterbalancer. The obtained experimental results are in full agreement with the theoretical prediction. From experiment, the vibration export at driving frequency was reduced 57-fold at practically the same electrical current and power consumed by the compressor actuator as compared with the basic cooler.

Veprik, A.; Nachman, I.; Pundak, N.

2009-05-01

18

Une porte optique intensificatrice picoseconde a gain eleve: Caracterisation et application potentielle en imagerie de petits objets places dans des milieux diffusants  

NASA Astrophysics Data System (ADS)

Dans cette etude, nous avons developpe un amplificateur a colorant possedant ces deux caracteristiques. Le colorant choisi, l'iodure de 3,3'-dimethyloxatricarbocyanine (methyl-DOTCI), possede un epaulement dans la bande d'absorption a 620 nm ce qui convient bien a notre pompe femtoseconde. De plus, son maximum de fluorescence est a 720 nm ce qui est particulierement interessant dans le cas des etudes avec des tissus biologiques humains. En effet, la fenetre dite "therapeutique" se situe dans les longueurs d'onde rouge et proche infrarouge. Le phenomene d'amplification, qui se produit dans des conditions experimentales precises, est en fait une emission stimulee du colorant qui est largement favorisee par rapport a sa fluorescence naturelle (emission spontanee). L'arrivee du signal incident, dont la longueur d'onde correspond au saut energetique entre l'etat fondamental et l'etat excite ou se trouvent les molecules, provoque une avalanche coherente de celles-ci vers l'etat fondamental generant ainsi l'emission stimulee. Une des conditions necessaires pour l'obtention d'un gain eleve est que la duree de l'impulsion de pompe soit inferieure au temps de relaxation des molecules ainsi qu'inferieure au temps requis pour effectuer un trajet dans la cellule de colorant. Ceci nous a permis d'amplifier un signal incident par un facteur entre 103 et 104. De plus, ce gain eleve n'est observe qu'a l'interieur d'une fenetre temporelle d'environ 10 picosecondes. Nous avons integre cet amplificateur a notre montage de transillumination afin d'acquerir des images d'un patron de lignes opaques immerge dans un milieu diffusant liquide. Des images de lignes ayant une resolution spatiale de 200 mum ont ete obtenues. La cible etait placee au centre d'un melange contenant des proportions variables de lait et d'eau. Deux longueurs de trajet optique dans la solution ont ete utilisees: 30 et 50 mm. Pour determiner les proprietes optiques de notre milieu diffusant, nous avons mis au point une technique de caracterisation basee sur la distribution radiale des photons transmis a travers le milieu. Deux parametres de transport, les coefficients de diffusion effectif (mus') et d'absorption (mu a), caracterisent la forme et l'amplitude du profil radial. Le fit des courbes experimentales a des courbes simulees nous a permis d'extraire ces coefficients. Les courbes simulees ont ete realisees grace a une simulation Monte Carlo qui incorpore les conditions experimentales de notre montage de caracterisation. (Abstract shortened by UMI.)

Marengo, Stephanie

19

A contractile and counterbalancing adhesion system controls the 3D shape of crawling cells.  

PubMed

How adherent and contractile systems coordinate to promote cell shape changes is unclear. Here, we define a counterbalanced adhesion/contraction model for cell shape control. Live-cell microscopy data showed a crucial role for a contractile meshwork at the top of the cell, which is composed of actin arcs and myosin IIA filaments. The contractile actin meshwork is organized like muscle sarcomeres, with repeating myosin II filaments separated by the actin bundling protein ?-actinin, and is mechanically coupled to noncontractile dorsal actin fibers that run from top to bottom in the cell. When the meshwork contracts, it pulls the dorsal fibers away from the substrate. This pulling force is counterbalanced by the dorsal fibers' attachment to focal adhesions, causing the fibers to bend downward and flattening the cell. This model is likely to be relevant for understanding how cells configure themselves to complex surfaces, protrude into tight spaces, and generate three-dimensional forces on the growth substrate under both healthy and diseased conditions. PMID:24711500

Burnette, Dylan T; Shao, Lin; Ott, Carolyn; Pasapera, Ana M; Fischer, Robert S; Baird, Michelle A; Der Loughian, Christelle; Delanoe-Ayari, Helene; Paszek, Matthew J; Davidson, Michael W; Betzig, Eric; Lippincott-Schwartz, Jennifer

2014-04-14

20

Compensator design for improved counterbalancing in high speed atomic force microscopy  

PubMed Central

High speed atomic force microscopy can provide the possibility of many new scientific observations and applications ranging from nano-manufacturing to the study of biological processes. However, the limited imaging speed has been an imperative drawback of the atomic force microscopes. One of the main reasons behind this limitation is the excitation of the AFM dynamics at high scan speeds, severely undermining the reliability of the acquired images. In this research, we propose a piezo based, feedforward controlled, counter actuation mechanism to compensate for the excited out-of-plane scanner dynamics. For this purpose, the AFM controller output is properly filtered via a linear compensator and then applied to a counter actuating piezo. An effective algorithm for estimating the compensator parameters is developed. The information required for compensator design is extracted from the cantilever deflection signal, hence eliminating the need for any additional sensors. The proposed approach is implemented and experimentally evaluated on the dynamic response of a custom made AFM. It is further assessed by comparing the imaging performance of the AFM with and without the application of the proposed technique and in comparison with the conventional counterbalancing methodology. The experimental results substantiate the effectiveness of the method in significantly improving the imaging performance of AFM at high scan speeds.

Bozchalooi, I. S.; Youcef-Toumi, K.; Burns, D. J.; Fantner, G. E.

2011-01-01

21

Moderating the interaction between procedural justice and decision frame: the counterbalancing effect of personality traits.  

PubMed

This study examined the framing effect of decision making in contexts in which the issue of social justice matters as well as the moderating effects of personality traits on the relationship between justice and framing effects. The authors manipulated procedural justice and outcome valence of the decision frame within two vignettes and measured two personality traits (self-efficacy and anxiety) of participants. The results from 363 participants showed that the moderating effects of personality traits counterbalanced the interaction between justice and framing, such that for individuals with high self-efficacy/low trait anxiety, justice effects were larger in negative framing than in positive framing; those with the opposite disposition exhibited the opposite pattern. These effects were interpreted in terms of an attribution process as the information processing strategy. The aforementioned findings suggest that the justice and decision theories can be developed to account for the moderating effects of personality traits. Some limitations of this study and the direction of future research are also discussed. PMID:23469475

Sasaki, Hiroyuki; Hayashi, Yoichiro

2013-01-01

22

Assessing the impact of user-centered research on a clinical trial eHealth tool via counterbalanced research design  

Microsoft Academic Search

ObjectiveInformatics applications have the potential to improve participation in clinical trials, but their design must be based on user-centered research. This research used a fully counterbalanced experimental design to investigate the effect of changes made to the original version of a website, http:\\/\\/BreastCancerTrials.org\\/, and confirm that the revised version addressed and reinforced patients' needs and expectations.DesignParticipants included women who had

Nancy L. Atkinson; Holly A. Massett; Christy Mylks; Lauren A. McCormack; Julia Kish-Doto; Bradford W. Hesse; Min Qi Wang

2011-01-01

23

Elevated expression of p53 gain-of-function mutation R175H in endometrial cancer cells can increase the invasive phenotypes by activation of the EGFR\\/PI3K\\/AKT pathway  

Microsoft Academic Search

BACKGROUND: p53 is the most commonly mutated tumor suppressor gene in human cancers. In addition to the loss of tumor suppression function and exertion of dominant-negative effects over the remaining wild-type protein, several p53 mutants can gain novel oncogenic functions (gain-of-function, GOF) that actively regulate cancer development and progression. In human endometrial cancer, p53 mutation is more often associated with

Peixin Dong; Zhujie Xu; Nan Jia; Dajin Li; Youji Feng

2009-01-01

24

Human iNKT and MAIT cells exhibit a PLZF-dependent proapoptotic propensity that is counterbalanced by XIAP  

PubMed Central

Invariant natural killer (iNKT) T cells and mucosal-associated invariant T (MAIT) cells represent peculiar T-lymphocyte subpopulations with innate-like properties that differ from conventional T cells. iNKT are reduced in the primary immunodeficiency caused by mutations in the X-linked inhibitor of apoptosis (XIAP). By studying the mechanism of this depletion, we herein report that iNKT cells exhibit a high susceptibility to apoptosis that is not observed with conventional T cells. Elevated expression of caspases 3 and 7 accounts for the proapoptotic phenotype of iNKT cells, which is inhibited by XIAP although it exerts a moderate effect in conventional T cells. Similarly, MAIT cells exhibit a proapoptotic propensity with elevated expression of activated caspases and are decreased in XIAP-deficient individuals. Knockdown of the transcription factor PLZF/ZBTB-16, which is involved in the effector program of iNKT cells, diminishes their proapoptotic phenotype. Conversely, overexpression of PLZF/ZBTB-16 in conventional T cells leads to a proapoptotic phenotype. Our findings identify a previously unknown pathway of regulation of innate-like T-cell homeostasis depending on XIAP and PLZF. The proapoptotic feature of iNKT cells also gives a reliable explanation of their exhaustion observed in different human conditions including the XIAP immunodeficiency.

Gerart, Stephane; Siberil, Sophie; Martin, Emmanuel; Lenoir, Christelle; Aguilar, Claire; Picard, Capucine; Lantz, Olivier; Fischer, Alain; Latour, Sylvain

2013-01-01

25

A hoist to the heavens [space elevators  

Microsoft Academic Search

This paper discusses the possibility of using space elevators as an alternative to rocket boosters for space exploration. With the advent of carbon nanotube composites, the space elevator concept has fast been gaining mainstream acceptance. With a space elevator providing cheap, easy, low-risk access to space, people's lives on Earth could be immeasurably enhanced as the wealth of the solar

B. C. Edwards

2005-01-01

26

Weight Gain during Pregnancy  

MedlinePLUS

... weight gain during pregnancy? Use our weight-gain tracking chart to follow your progress. For more information ... During Pregnancy Last reviewed September 2009 See also: Tracking your weight gain , How your baby grows Most ...

27

location plan, floor plan, west elevation, north elevation, north elevation ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

location plan, floor plan, west elevation, north elevation, north elevation with porch removed - Chopawamsic Recreational Demonstration Area - Cabin Camp 1, Staff Quarters, Prince William Forest Park, Triangle, Prince William County, VA

28

No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population.  

PubMed

It is often suggested that coffee causes dehydration and its consumption should be avoided or significantly reduced to maintain fluid balance. The aim of this study was to directly compare the effects of coffee consumption against water ingestion across a range of validated hydration assessment techniques. In a counterbalanced cross-over design, 50 male coffee drinkers (habitually consuming 3-6 cups per day) participated in two trials, each lasting three consecutive days. In addition to controlled physical activity, food and fluid intake, participants consumed either 4×200 mL of coffee containing 4 mg/kg caffeine (C) or water (W). Total body water (TBW) was calculated pre- and post-trial via ingestion of Deuterium Oxide. Urinary and haematological hydration markers were recorded daily in addition to nude body mass measurement (BM). Plasma was analysed for caffeine to confirm compliance. There were no significant changes in TBW from beginning to end of either trial and no differences between trials (51.5±1.4 vs. 51.4±1.3 kg, for C and W, respectively). No differences were observed between trials across any haematological markers or in 24 h urine volume (2409±660 vs. 2428±669 mL, for C and W, respectively), USG, osmolality or creatinine. Mean urinary Na(+) excretion was higher in C than W (p?=?0.02). No significant differences in BM were found between conditions, although a small progressive daily fall was observed within both trials (0.4±0.5 kg; p<0.05). Our data show that there were no significant differences across a wide range of haematological and urinary markers of hydration status between trials. These data suggest that coffee, when consumed in moderation by caffeine habituated males provides similar hydrating qualities to water. PMID:24416202

Killer, Sophie C; Blannin, Andrew K; Jeukendrup, Asker E

2014-01-01

29

Gain weighted eigenspace assignment  

NASA Technical Reports Server (NTRS)

This report presents the development of the gain weighted eigenspace assignment methodology. This provides a designer with a systematic methodology for trading off eigenvector placement versus gain magnitudes, while still maintaining desired closed-loop eigenvalue locations. This is accomplished by forming a cost function composed of a scalar measure of error between desired and achievable eigenvectors and a scalar measure of gain magnitude, determining analytical expressions for the gradients, and solving for the optimal solution by numerical iteration. For this development the scalar measure of gain magnitude is chosen to be a weighted sum of the squares of all the individual elements of the feedback gain matrix. An example is presented to demonstrate the method. In this example, solutions yielding achievable eigenvectors close to the desired eigenvectors are obtained with significant reductions in gain magnitude compared to a solution obtained using a previously developed eigenspace (eigenstructure) assignment method.

Davidson, John B.; Andrisani, Dominick, II

1994-01-01

30

Optimal Weight Gain  

Microsoft Academic Search

Optimal birth weight and outcome are influenced by maternal weight gain. Low gestational weight gain is associated with poor\\u000a fetal growth and risk of preterm delivery. Excessive weight gain affects infant growth, body fatness in childhood, and the\\u000a potential for postpartum weight retention and future obesity. Guidelines from the Institute of Medicine recommend that a woman\\u000a with a normal body

Grace A. Falciglia; Kristin H. Coppage

31

Preventing Weight Gain  

MedlinePLUS

... Calculator Children's BMI Tool for Schools Child and Teen - About BMI Measuring Children's Height and Weight Accurately At Home Balancing Calories Other Factors in Weight Gain Preventing Weight Gain Losing Weight Getting Started Improving Your Eating Habits Keeping it Off Healthy Eating for a Healthy ...

32

Invention and Gain Analysis.  

ERIC Educational Resources Information Center

Gain analysis is applied to the invention of the sewing needle as well as different sewing implements and modes of sewing. The analysis includes a two-subject experiment. To validate the generality of gain heuristics and underlying switching processes, the invention of the assembly line is also analyzed. (TJH)

Weber, Robert J.; Dixon, Stacey

1989-01-01

33

Weight gain - unintentional  

MedlinePLUS

... changes or medical problems can also cause unintentional weight gain. This may be due to: Cushing syndrome Underactive thyroid, or low thyroid (Hypothyroidism) Polycystic ovary syndrome Menopause Pregnancy Bloating, or swelling due to a ...

34

Antenna Height Gain Experiment.  

National Technical Information Service (NTIS)

The report presents the results of the antenna height gain experiment performed in the Chicago Region at four different sites. Two bands, VHF and UHF, are analyzed for their signal strength and occupancy variation versus antenna heights. These results are...

O. Efremov

1976-01-01

35

Pressure-gain combustion  

SciTech Connect

Pulse combustion has been proposed for gas turbine applications in many early articles and more recently has been demonstrated to produce so-called ``pressure-gain`` in a small gas turbine. The basic concept is that the oscillatory combustion occurs as a constant-volume process, producing a gain in the stagnation pressure of air flowing through the combustor, rather than the pressure loss associated with conventional, steady combustion. If properly utilized, this pressure-gain could enhance simple-cycle gas turbine efficiency several percent, depending on the operating conditions. In addition, pulse combustors have demonstrated relatively low NO{sub x} pollutant levels in some applications. The combined potential for higher cycle efficiency and lower pollutant levels is the basis for the present investigation. Tests in progress at the Morgantown Energy Technology Center (METC) have considered a baseline pulse combustor configuration that has shown good oscillating performance, low NO{sub x} emissions, but disappointing results in terms of pressure-gain. However, a combination of numeric simulations and test data suggest that pressure-gain can be produced by a select combination of operating conditions and combustor geometry, but is especially sensitive to the combustor inlet geometry. Tests in progress will evaluate the effect of inlet geometry and operating pressure on both pollutant emissions and pressure-gain.

Richards, G.A.; Yip, J.; Gemmen, R.S.; Janus, M.C.; Norton, T. [USDOE Morgantown Energy Technology Center, WV (United States); Rogers, W.A. [EG and G Washington Analytical Services Center, Inc., Morgantown, WV (United States)

1993-11-01

36

Receiver Gain Modulation Circuit  

NASA Technical Reports Server (NTRS)

A receiver gain modulation circuit (RGMC) was developed that modulates the power gain of the output of a radiometer receiver with a test signal. As the radiometer receiver switches between calibration noise references, the test signal is mixed with the calibrated noise and thus produces an ensemble set of measurements from which ensemble statistical analysis can be used to extract statistical information about the test signal. The RGMC is an enabling technology of the ensemble detector. As a key component for achieving ensemble detection and analysis, the RGMC has broad aeronautical and space applications. The RGMC can be used to test and develop new calibration algorithms, for example, to detect gain anomalies, and/or correct for slow drifts that affect climate-quality measurements over an accelerated time scale. A generalized approach to analyzing radiometer system designs yields a mathematical treatment of noise reference measurements in calibration algorithms. By treating the measurements from the different noise references as ensemble samples of the receiver state, i.e. receiver gain, a quantitative description of the non-stationary properties of the underlying receiver fluctuations can be derived. Excellent agreement has been obtained between model calculations and radiometric measurements. The mathematical formulation is equivalent to modulating the gain of a stable receiver with an externally generated signal and is the basis for ensemble detection and analysis (EDA). The concept of generating ensemble data sets using an ensemble detector is similar to the ensemble data sets generated as part of ensemble empirical mode decomposition (EEMD) with exception of a key distinguishing factor. EEMD adds noise to the signal under study whereas EDA mixes the signal with calibrated noise. It is mixing with calibrated noise that permits the measurement of temporal-functional variability of uncertainty in the underlying process. The RGMC permits the evaluation of EDA by modulating the receiver gain using an external signal. Without the RGMC, samples of calibrated references from radiometers form an ensemble data set of the natural occurring fluctuations within a receiver. By driving the gain of an otherwise stable receiver with an external signal, the conceptual framework and generalization of the mathematics of EDA can be tested. A series of measurements was conducted to evaluate and characterize the performance of the RGMC. Test signals stepped the RGMC across its dynamic range of performance using a radiometer that sampled four noise references; analysis indicates that the RGMC successfully modulated the receiver gain with an external signal. Calibration algorithms applied to four noise references demonstrate the RGMC produced ensemble data sets of the external signal.

Jones, Hollis; Racette, Paul; Walker, David; Gu, Dazhen

2011-01-01

37

Pressure-gain combustion.  

National Technical Information Service (NTIS)

Pulse combustion has been proposed for gas turbine applications in many early articles and more recently has been demonstrated to produce so-called ''pressure-gain'' in a small gas turbine. The basic concept is that the oscillatory combustion occurs as a ...

G. A. Richards J. Yip R. S. Gemmen M. C. Janus T. Norton

1993-01-01

38

Interferometer Design for Elevation Angle Estimation  

Microsoft Academic Search

Radars that are developed for the purpose of monitoring aircraft landings in the terminal air traffic control system can be designed to exploit the relatively high signal-to-noise ratio that characterizes the power budgets calculated for such a link. An interferometer using a pair of low gain antennas can be used to obtain passive coverage over a targe azimuth and elevation

Robert McAulay

1977-01-01

39

Receiver gain function: the actual NMR receiver gain  

PubMed Central

The observed NMR signal size depends on the receiver gain parameter. We propose a receiver gain function to characterize how much the raw FID is amplified by the receiver as a function of the receiver gain setting. Although the receiver is linear for a fixed gain setting, the actual gain of the receiver may differ from what the gain setting suggests. Nevertheless, for a given receiver, we demonstrate that the receiver gain function can be calibrated. Such a calibration enables accurate comparison of separately acquired NMR signals in quantitative analysis, which frequently requires different receiver gain settings to avoid receiver saturation or achieve optimum sensitivity. The application of receiver gain function, along with the definition of receiving efficiency, allows easy concentration determination by a single internal or external concentration reference.

Mo, Huaping; Harwood, John S.; Raftery, Daniel

2011-01-01

40

Helicopter high gain control  

NASA Technical Reports Server (NTRS)

High gain control is explored through a design study of the CH-47B helicopter. The plans are designed to obtain the maximum bandwidth possible given the hardware constraints. Controls are designed with modal control theory to specific bandwidths and closed loop mode shapes. Comparisons are made to an earlier complementary filter approach. Bandwidth improvement by removal of limitations is explored in order to establish hardware and mechanization options. Improvements in the pitch axis control system and in the rate gyro sensor noise characteristics in all axes are discussed. The use of rotor state feedback is assessed.

Cunningham, T. B.; Nunn, E. C.

1979-01-01

41

USGS Elevation Monument  

USGS Multimedia Gallery

USGS elevation monument for a level line run from Mojave, California to Keeler, California. The line ran through such places as 18-Mile Station, Dixie, Indan Wells, Little Lake, and Olancha. Elevations were based on Benecia datum....

2009-10-13

42

The Space Elevator  

NASA Astrophysics Data System (ADS)

The Space Elevator is conceived to be a carbon nanotube ribbon stretching from an Earth station in the ocean on the equator to far beyond geosynchronous altitude. This elevator co-rotates with the Earth. Climbers ascend the ribbon using power beamed from Earth to launch spacecraft in orbit or to other worlds. The requirements of the ribbon material, challenges to the building of the space elevator, deployment and the promise of the space elevator are briefly discussed in this paper.

Laubscher, Bryan E.

2005-09-01

43

National Elevation Dataset  

USGS Publications Warehouse

The National Elevation Dataset (NED) is a new raster product assembled by the U.S. Geological Survey (USGS). The NED is designed to provide national elevation data in a seamless form with a consistent datum, elevation unit, and projection. Data corrections were made in the NED assembly process to minimize artifacts, permit edge matching, and fill sliver areas of missing data.

Geological Survey (U.S.)

1999-01-01

44

High gain observers with updated gain and homogeneous correction terms  

Microsoft Academic Search

Exploiting dynamic scaling and homogeneity in the bi-limit, we develop a new class of high gain observers which incorporate a gain update law and nonlinear output error injection terms. A broader class of systems can be addressed and the observer gain is better fitted to the incremental rate of the nonlinearities. The expected improved performance is illustrated.

V. Andrieu; L. Praly; Alessandro Astolfi

2009-01-01

45

26 CFR Net - in gain.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false in gain. Net Example: Net recognized built Internal Revenue INTERNAL REVENUE...Corporations and Their Shareholders § 1.1374-2 Net recognized built-in gain. (a) In general....

2011-04-01

46

Acting to gain information  

NASA Technical Reports Server (NTRS)

This report is concerned with agents that act to gain information. In previous work, we developed agent models combining qualitative modeling with real-time control. That work, however, focused primarily on actions that affect physical states of the environment. The current study extends that work by explicitly considering problems of active information-gathering and by exploring specialized aspects of information-gathering in computational perception, learning, and language. In our theoretical investigations, we analyzed agents into their perceptual and action components and identified these with elements of a state-machine model of control. The mathematical properties of each was developed in isolation and interactions were then studied. We considered the complexity dimension and the uncertainty dimension and related these to intelligent-agent design issues. We also explored active information gathering in visual processing. Working within the active vision paradigm, we developed a concept of 'minimal meaningful measurements' suitable for demand-driven vision. We then developed and tested an architecture for ongoing recognition and interpretation of visual information. In the area of information gathering through learning, we explored techniques for coping with combinatorial complexity. We also explored information gathering through explicit linguistic action by considering the nature of conversational rules, coordination, and situated communication behavior.

Rosenchein, Stanley J.; Burns, J. Brian; Chapman, David; Kaelbling, Leslie P.; Kahn, Philip; Nishihara, H. Keith; Turk, Matthew

1993-01-01

47

Gravity Deformation and Gain Loss of 12m Reflector Antenna  

Microsoft Academic Search

Based on the structural analysis, a gravity deformation model is derived by superposition that described the main reflector distortions over the entire range of elevation angles. The aperture efficiency and gain loss is calculated using Ruze formula. To simulate the gravity deformation, a finite element model of antenna structure is created and input to the ANSYS program. The displacements of

Wei Wang; Baoyan Duan

2007-01-01

48

emGain: Determination of EM gain of CCD  

NASA Astrophysics Data System (ADS)

The determination of the EM gain of the CCD is best done by fitting the histogram of many low-light frames. Typically, the dark+CIC noise of a 30ms frame itself is a sufficient amount of signal to determine accurately the EM gain with about 200 512x512 frames. The IDL code emGain takes as an input a cube of frames and fit the histogram of all the pixels with the EM stage output probability function. The function returns the EM gain of the frames as well as the read-out noise and the mean signal level of the frames.

Daigle, Olivier; Carignan, Claude; Blais-Ouellette, Sebastien

2012-01-01

49

Space Elevator: Stability  

Microsoft Academic Search

Many papers have been published on engineering and economic aspects of the Space Elevator. The Elevator, however, is a very special and unusual astronomical body. Its behavior in space is affected not only by the attraction of the Earth and by the “centrifugal force” but also by the attraction of the Sun and the Moon, by the detailed shape of

Lubos Perek

2008-01-01

50

Predicting Gains in Dementia Caregiving  

Microsoft Academic Search

Background: Caregiver gain is an important yet less-explored phenomenon. Being conceptually distinct from burden, factors associated with burden and gain can differ. This study aims to explore factors associated with the experience of gains in dementia caregiving. Method: Cross-sectional study involving caregivers recruited from a tertiary hospital dementia clinic and the local Alzheimer’s Association. Caregivers completed a questionnaire containing the

Tau Ming Liew; Nan Luo; Wai Yee Ng; Hui Ling Chionh; Jenny Goh; Philip Yap

2010-01-01

51

Hearing Aid Evaluation: Predicting Speech Gain from Insertion Gain.  

ERIC Educational Resources Information Center

This study, involving 11 older males with mild or moderate sensorineural loss, tested whether speech gain that results from a hearing aid fitting is predictable on the basis of unaided performance intensity curve, unaided narrow-band sound field thresholds, hearing aid insertion gain as a function of frequency, ambient noise, and internal hearing…

Dillon, Harvey

1993-01-01

52

Pregnancy weight gain and breast cancer risk  

PubMed Central

Background Elevated pregnancy estrogen levels are associated with increased risk of developing breast cancer in mothers. We studied whether pregnancy weight gain that has been linked to high circulating estrogen levels, affects a mother's breast cancer risk. Methods Our cohort consisted of women who were pregnant between 1954–1963 in Helsinki, Finland, 2,089 of which were eligible for the study. Pregnancy data were collected from patient records of maternity centers. 123 subsequent breast cancer cases were identified through a record linkage to the Finnish Cancer Registry, and the mean age at diagnosis was 56 years (range 35 – 74). A sample of 979 women (123 cases, 856 controls) from the cohort was linked to the Hospital Inpatient Registry to obtain information on the women's stay in hospitals. Results Mothers in the upper tertile of pregnancy weight gain (>15 kg) had a 1.62-fold (95% CI 1.03–2.53) higher breast cancer risk than mothers who gained the recommended amount (the middle tertile, mean: 12.9 kg, range 11–15 kg), after adjusting for mother's age at menarche, age at first birth, age at index pregnancy, parity at the index birth, and body mass index (BMI) before the index pregnancy. In a separate nested case-control study (n = 65 cases and 431 controls), adjustment for BMI at the time of breast cancer diagnosis did not modify the findings. Conclusions Our study suggests that high pregnancy weight gain increases later breast cancer risk, independently from body weight at the time of diagnosis.

Kinnunen, Tarja I; Luoto, Riitta; Gissler, Mika; Hemminki, Elina; Hilakivi-Clarke, Leena

2004-01-01

53

Dynamic high gain observer design  

Microsoft Academic Search

A dynamic high gain based observer is proposed for the class of uniformly observable systems which are observable for any inputs. The main feature of this observer consists in an appropriate calibration of the observation gain through a single parameter governed by some scalar Riccati equation. Simulation results are given in order to highlight the performances of the proposed observer,

M. Farza; M. M'Saad; M. Oueder; L. Sellami; R. Ben Abdennour

2009-01-01

54

Gain control in reflex pathways  

Microsoft Academic Search

Summary form only given. A series of experiments was undertaken to determine the gain of the stretch reflex in decerebrate cats. Stretches are applied through a servo-controlled motor that receives length and velocity feedback which are adjusted so that it behaves like a spring of a particular stiffness. As the stiffness decreases the gain of the reflex increases until the

R. B. Stein; S. DeSerres; D. J. Bennett

1992-01-01

55

Gain-Spread-Excitation Theorem.  

National Technical Information Service (NTIS)

This paper proposed an extension of the Madey gain-spread theorem to two-dimensional wigglers and shown it to be quite generally valid. It has the important consequence that an Free Electron Laser(FEL) wiggler which yields gain must at the same time gener...

N. Kroll M. Rosenbluth

1984-01-01

56

A Nanotube Space Elevator  

NSDL National Science Digital Library

In this video adapted from NOVA scienceNOW, find out about the discovery of a new building material, the carbon nanotube, whose physical properties could theoretically enable the creation of a 22,000-mile elevator to space.

Foundation, Wgbh E.

2008-09-08

57

Elevated Temperature Biaxial Fatigue.  

National Technical Information Service (NTIS)

A three year experimental program for studying elevated temperature biaxial fatigue of a nickel based alloy Hastelloy-X has been completed. A new high temperature fatigue test facility with unique capabilities has been developed. Effort was directed towar...

E. H. Jordan

1984-01-01

58

Light: Isometric Casing with Lens, South Elevation, North Elevation, Top ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Light: Isometric Casing with Lens, South Elevation, North Elevation, Top Plan, Base Plan; Fresnel Lens: Isometric, Elevation, Plan - Fort Washington, Fort Washington Light, Northeast side of Potomac River at Fort Washington Park, Fort Washington, Prince George's County, MD

59

location map, floor plan, north elevation, north elevation with porch ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

location map, floor plan, north elevation, north elevation with porch removed, south elevation, building section - Chopawamsic Recreational Demonstration Area - Cabin Camp 1, Help's Quarters, Prince William Forest Park, Triangle, Prince William County, VA

60

Elevators or stairs?  

PubMed Central

Background: Staff in hospitals frequently travel between floors and choose between taking the stairs or elevator. We compared the time savings with these two options. Methods: Four people aged 26–67 years completed 14 trips ranging from one to six floors, both ascending and descending. We compared the amount of time per floor travelled by stairs and by two banks of elevators. Participants reported their fatigue levels using a modified Borg scale. We performed two-way analysis of variance to compare the log-transformed data, with participant and time of day as independent variables. Results: The mean time taken to travel between each floor was 13.1 (standard deviation [SD] 1.7) seconds by stairs and 37.5 (SD 19.0) and 35.6 (SD 23.1) seconds by the two elevators (F = 8.61, p < 0.001). The difference in time taken to travel by stairs and elevator equaled about 15 minutes a day. Self-reported fatigue was less than 13 (out of 20) on the Borg scale for all participants, and they all stated that they were able to continue their duties without resting. The extra time associated with elevator use was because of waiting for its arrival. There was a difference in the amount of time taken to travel by elevator depending on the time of day and day of the week. Interpretation: Taking the stairs rather than the elevator saved about 15 minutes each workday. This 3% savings per workday could translate into improved productivity as well as increased fitness.

Shah, Sachin; O'Byrne, Michael; Wilson, Merne; Wilson, Thomas

2011-01-01

61

Space Elevator: Stability  

NASA Astrophysics Data System (ADS)

Many papers have been published on engineering and economic aspects of the Space Elevator. The Elevator, however, is a very special and unusual astronomical body. Its behavior in space is affected not only by the attraction of the Earth and by the "centrifugal force" but also by the attraction of the Sun and the Moon, by the detailed shape of the Earth, by the presence of space debris, etc. Not all of the minor effects have been adequately studied. The size of the Space Elevator and its lack of resistance against buckling or bending require a detailed study of its stability, both in its initial phase as a geostationary (GEO) satellite as well as in its operational phase as a "sling". Lunisolar perturbations and other minor forces may affect the stability in the initial phase and will cause oscillations in the operational phase. Station-keeping thrusters will have to be mounted at selected points along the cable in order to maintain stability. In addition, the thrusters will perform local maneuvers for avoiding collisions with passing space debris. The control system of thrusters has to be adaptive, reacting fast to actual situation and rectifying the attitude of the Elevator whenever necessary. A further advantage of the thrusters is a possibility to locate the Elevator at any longitude, possibly looking for a region with minimum traffic at GEO distance. Extensive numerical simulations will have to be performed in order to determine elements of the thrusters and their control system.

Perek, Lubos

2008-04-01

62

Severe obesity, gestational weight gain, and adverse birth outcomes123  

PubMed Central

Background: The 2009 Institute of Medicine (IOM) Committee to Reevaluate Gestational Weight Gain Guidelines concluded that there were too few data to inform weight-gain guidelines by obesity severity. Therefore, the committee recommended a single range, 5–9 kg at term, for all obese women. Objective: We explored associations between gestational weight gain and small-for-gestational-age (SGA) births, large-for-gestational-age (LGA) births, spontaneous preterm births (sPTBs), and medically indicated preterm births (iPTBs) among obese women who were stratified by severity of obesity. Design: We studied a cohort of singleton, live-born infants without congenital anomalies born to obesity class 1 (prepregnancy body mass index [BMI (in kg/m2)]: 30–34.9; n = 3254), class 2 (BMI: 35–39.9; n = 1451), and class 3 (BMI: ?40; n = 845) mothers. We defined the adequacy of gestational weight gain as the ratio of observed weight gain to IOM-recommended gestational weight gain. Results: The prevalence of excessive gestational weight gain declined, and weight loss increased, as obesity became more severe. Generally, weight loss was associated with an elevated risk of SGA, iPTB, and sPTB, and a high weight gain tended to increase the risk of LGA and iPTB. Weight gains associated with probabilities of SGA and LGA of ?10% and a minimal risk of iPTB and sPTB were as follows: 9.1–13.5 kg (obesity class 1), 5.0–9 kg (obesity class 2), 2.2 to <5.0 kg (obesity class 3 white women), and <2.2 kg (obesity class 3 black women). Conclusion: These data suggest that the range of gestational weight gain to balance risks of SGA, LGA, sPTB, and iPTB may vary by severity of obesity.

Bodnar, Lisa M; Siega-Riz, Anna Maria; Simhan, Hyagriv N; Himes, Katherine P; Abrams, Barbara

2010-01-01

63

Storms as agents of wetland elevation change: their impact on surface and subsurface sediment processes  

USGS Publications Warehouse

Direct measures of the impact of major storms on wetland sediment elevation are rare. Recently developed techniques have enabled simultaneous, quantitative observations of surface and subsurface processes affecting sediment elevation. An analysis of ten wetland sites revealed the following patterns of sediment elevation change after storm passage: (1) elevation change equivalent to sediment accretion or erosion, (2) elevation loss in spite of sediment deposition, or in excess of erosion, and (3) elevation gain greater than the amount of sediment accretion. These observations suggest that storms influence sediment elevation not only by sediment deposition and erosion but also through subsurface processes of sediment compaction, root growth and decomposition, and water flux. Wetlands receiving a substantial deposit of sediment did not always realize an equivalent elevation gain. Some realized a net loss in elevation as a result of sediment compaction apparently caused by the weight of the sediment deposit or the tidal surge waters, or both. Sediment elevation collapsed in two mangrove forests with highly organic substrate when the storm killed the forest. In two marshes, elevation gain exceeded deposition apparently through increased sediment water storage or plant root growth via nutrient enrichment from storm sediment deposits. The elevation responses were either temporary or permanent on an ecological time scale (> 8 years). In one organic marsh substrate, compaction was followed by expansion, only to be compacted again by another storm. Thus the elevation response of coastal wetlands to major storms varied depending on local substrate conditions and degree of storm impact.

Cahoon, D.R.

2003-01-01

64

Modal Analysis and Gain Estimation  

NASA Technical Reports Server (NTRS)

Interactive program yields eigenvectors, eigenvalues, and gains for feedback-control systems. Interactive Modal Analysis and Gain Estimation System (IMAGES) provides eigensystem synthesis capability to control-system engineer. IMAGES modular and flexible. Capable of both modal and spectral synthesis of multi-input control systems. IMAGES user-oriented, interactive program that frees engineer to concentrate on eigensystem synthesis. Engineer provided with scratch-pad capability that speeds control-system design.

Jones, R. L.

1986-01-01

65

The Lloyd L. Gaines Collection  

NSDL National Science Digital Library

Born in 1911, Lloyd Lionel Gaines was one of eleven children. Gaines excelled in his studies and applied to the University of Missouri School of Law in 1936. He was denied admission solely on the grounds that Missouri's state constitution called for "separate education of the races." Gaines did not back down from this injustice, and he sought legal assistance from the NAACP. In 1938, Gaines won his case before the United States Supreme Court, but tragically Gaines disappeared at age 28 in Chicago and was never seen or heard from again. This engaging collection from the University of Missouri Law Library brings together documents related to Gaines's life, including photographs, family correspondence, materials related to his Supreme Court case, and related secondary materials. Visitors to the site can perform a simple search across all the materials, or dig in deeper by perform a citation search. Legal scholars will find the Case Materials area particularly engaging, as it includes links to the trial briefs, respondents' statements, and so on.

66

National Elevation Dataset  

USGS Publications Warehouse

The National Elevation Dataset (NED) is a new raster product assembled by the U.S. Geological Survey. NED is designed to provide National elevation data in a seamless form with a consistent datum, elevation unit, and projection. Data corrections were made in the NED assembly process to minimize artifacts, perform edge matching, and fill sliver areas of missing data. NED has a resolution of one arc-second (approximately 30 meters) for the conterminous United States, Hawaii, Puerto Rico and the island territories and a resolution of two arc-seconds for Alaska. NED data sources have a variety of elevation units, horizontal datums, and map projections. In the NED assembly process the elevation values are converted to decimal meters as a consistent unit of measure, NAD83 is consistently used as horizontal datum, and all the data are recast in a geographic projection. Older DEM's produced by methods that are now obsolete have been filtered during the NED assembly process to minimize artifacts that are commonly found in data produced by these methods. Artifact removal greatly improves the quality of the slope, shaded-relief, and synthetic drainage information that can be derived from the elevation data. Figure 2 illustrates the results of this artifact removal filtering. NED processing also includes steps to adjust values where adjacent DEM's do not match well, and to fill sliver areas of missing data between DEM's. These processing steps ensure that NED has no void areas and artificial discontinuities have been minimized. The artifact removal filtering process does not eliminate all of the artifacts. In areas where the only available DEM is produced by older methods, then "striping" may still occur.

U.S Geological Survey

2002-01-01

67

Gain estimation of RT-APD devices by means of TCAD numerical simulations  

Microsoft Academic Search

The design of Reach-Through Avalanche Photodiodes (RT-APD) for medium energy X-ray detection requires a previous optimization to guarantee elevated gain at the required operation conditions. A simple methodology to estimate the gain in RT-APD devices by using TCAD numerical simulations is proposed in this work. This technique offers the possibility to predict the gain in RT-APDs as a function of

I. Cortes; P. Fernandez-Martinez; D. Flores; S. Hidalgo; J. Rebollo

2011-01-01

68

Developmental Gains in Visuospatial Memory Predict Gains in Mathematics Achievement  

PubMed Central

Visuospatial competencies are related to performance in mathematical domains in adulthood, but are not consistently related to mathematics achievement in children. We confirmed the latter for first graders and demonstrated that children who show above average first-to-fifth grade gains in visuospatial memory have an advantage over other children in mathematics. The study involved the assessment of the mathematics and reading achievement of 177 children in kindergarten to fifth grade, inclusive, and their working memory capacity and processing speed in first and fifth grade. Intelligence was assessed in first grade and their second to fourth grade teachers reported on their in-class attentive behavior. Developmental gains in visuospatial memory span (d?=?2.4) were larger than gains in the capacity of the central executive (d?=?1.6) that in turn were larger than gains in phonological memory span (d?=?1.1). First to fifth grade gains in visuospatial memory and in speed of numeral processing predicted end of fifth grade mathematics achievement, as did first grade central executive scores, intelligence, and in-class attentive behavior. The results suggest there are important individual differences in the rate of growth of visuospatial memory during childhood and that these differences become increasingly important for mathematics learning.

Li, Yaoran; Geary, David C.

2013-01-01

69

Gain degradation and amplitude scintillation due to tropospheric turbulence  

NASA Technical Reports Server (NTRS)

It is shown that a simple physical model is adequate for the prediction of the long term statistics of both the reduced signal levels and increased peak-to-peak fluctuations. The model is based on conventional atmospheric turbulence theory and incorporates both amplitude and angle of arrival fluctuations. This model predicts the average variance of signals observed under clear air conditions at low elevation angles on earth-space paths at 2, 7.3, 20 and 30 GHz. Design curves based on this model for gain degradation, realizable gain, amplitude fluctuation as a function of antenna aperture size, frequency, and either terrestrial path length or earth-space path elevation angle are presented.

Theobold, D. M.; Hodge, D. B.

1978-01-01

70

Elevational spatial compounding.  

PubMed

Spatial compounding has long been explored to reduce coherent speckle noise in medical ultrasound. By laterally translating a one-dimensional array, partially correlated measurements made at different look directions can be obtained and incoherently averaged. The lateral resolution, however, is limited by the sub-array length used for each independent measurement. To reduce speckle contrast without compromising lateral resolution, a new spatial compounding technique using two-dimensional, anisotropic arrays is proposed. This technique obtains partially correlated measurements by steering the image plane elevationally with small inclinations. Incoherent averaging is then performed by adding image magnitudes. Therefore, contrast resolution is improved only at the price of a slightly wider elevational beam. Note that although anisotropic arrays have limited steering capability in elevation, grating lobes are not considered influential since only small inclinations are needed between measurements. Simulations have been performed to show both the change in spatial resolution and the improvement in contrast resolution. Results indicated minimal increase in the correlation length both laterally and axially. It was also shown that detectability can be significantly enhanced by increasing the number of measurements or increasing the differential inclination between measurements. This technique is therefore effective for reducing speckle noise while maintaining in-plane spatial resolution. Furthermore, it demonstrates a new application of two-dimensional anisotropic arrays in spite of their limited elevational steering capability. PMID:7839557

Li, P C; O'Donnell, M

1994-07-01

71

Commutated automatic gain control system  

NASA Technical Reports Server (NTRS)

A commutated automatic gain control system (AGC) was designed and constructed for the prototype Loran C receiver. The AGC is designed to improve the signal-to-signal ratio of the received Loran signals. The AGC design does not require any analog to digital conversion and it utilizes commonly available components. The AGC consists of: (1) a circuit which samples the peak of the envelope of the Loran signal to obtain an AGC voltage for each of three Loran stations, (2) a dc gain circuit to control the overall gain of the AGC system, and (3) an AGC amplification of the input RF signal. The performance of the AGC system was observed in bench and flight tests; it has improved the overall accuracy of the receiver. Improvements in the accuracy of the time difference calculations to within approx. + or - 1.5 microseconds of the observed time differnces for a given position are reported.

Yost, S. R.

1981-01-01

72

Welfare Gains from Financial Liberalization  

PubMed Central

Financial liberalization has been a controversial issue, as empirical evidence for growth enhancing effects is mixed. Here, we find sizable welfare gains from liberalization (cost to repression), though the gain in economic growth is ambiguous. We take the view that financial liberalization is a government policy that alters the path of financial deepening, while financial deepening is endogenously chosen by agents given a policy and occurs in transition towards a distant steady state. This history-dependent view necessitates the use of simulation analysis based on a growth model. Our application is a specific episode: Thailand from 1976 to 1996.

Townsend, Robert M.; Ueda, Kenichi

2010-01-01

73

Elevated temperature crack growth  

NASA Technical Reports Server (NTRS)

The objective of the Elevated Temperature Crack Growth Project is to evaluate proposed nonlinear fracture mechanics methods for application to combustor liners of aircraft gas turbine engines. During the first year of this program, proposed path-independent (P-I) integrals were reviewed for such applications. Several P-I integrals were implemented into a finite-element postprocessor which was developed and verified as part of the work. Alloy 718 was selected as the analog material for use in the forthcoming experimental work. A buttonhead, single-edge notch specimen was designed and verified for use in elevated-temperature strain control testing with significant inelastic strains. A crack mouth opening displacement measurement device was developed for further use.

Yau, J. F.; Malik, S. N.; Kim, K. S.; Vanstone, R. H.; Laflen, J. H.

1985-01-01

74

Elevated temperature envelope forming  

NASA Technical Reports Server (NTRS)

Elevated temperature envelope forming includes enclosing a part blank and form tool within an envelope sealed against the atmosphere, heat treating the combination while forming pressure holds the envelope and part against the form tool, and allowing part cool down to occur in an inert atmosphere with forming pressure removed. The forming pressure is provided by evacuating the envelope and may be aided by differential force applied between the envelope and the form tool.

Burg, Bruce M. (Inventor); Gane, David H. (Inventor); Starowski, Robert M. (Inventor)

1992-01-01

75

Gaining Perspective on Parenting Groups.  

ERIC Educational Resources Information Center

This theme issue offers a collection of articles focusing on support groups for parents of infants and toddlers, including the following: (1) "Gaining Perspective on Parenting Groups" (Nick Carter and Cathie Harvey) which reviews the purposes, history, and essential ingredients of such groups; (2) "The MELD Experience with Parent Groups" (Joyce…

Fenichel, Emily, Ed.

1996-01-01

76

The Gains from Vertical Scaling  

ERIC Educational Resources Information Center

It is often assumed that a vertical scale is necessary when value-added models depend upon the gain scores of students across two or more points in time. This article examines the conditions under which the scale transformations associated with the vertical scaling process would be expected to have a significant impact on normative interpretations…

Briggs, Derek C.; Domingue, Ben

2013-01-01

77

north elevation, south elevation, building section, window details Chopawamsic ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

north elevation, south elevation, building section, window details - Chopawamsic Recreational Demonstration Area - Cabin Camp 1, Main Arts and Crafts Lodge, Prince William Forest Park, Triangle, Prince William County, VA

78

location map, floor plan, building section, north elevation, west elevation, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

location map, floor plan, building section, north elevation, west elevation, door and window details - Chopawamsic Recreational Demonstration Area - Cabin Camp 1, Central Bath House, Prince William Forest Park, Triangle, Prince William County, VA

79

location plan, floor plan, building section, north elevation, west elevation, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

location plan, floor plan, building section, north elevation, west elevation, louver window detail, mechanical room door profile, partition profile - Chopawamsic Recreational Demonstration Area - Cabin Camp 1, Staff Bath House, Prince William Forest Park, Triangle, Prince William County, VA

80

44. VIEW OF ELEVATOR MOTOR LOCATED ABOVE TOP OF ELEVATOR ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

44. VIEW OF ELEVATOR MOTOR LOCATED ABOVE TOP OF ELEVATOR NEAR WEST WALL OF MST STATION 111 ANTEROOM - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 West, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

81

Refrigeration Plant, North Elevation, Second Floor Plan, East Elevation, Ground ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Refrigeration Plant, North Elevation, Second Floor Plan, East Elevation, Ground Floor Plan, Section A-A - Kennecott Copper Corporation, On Copper River & Northwestern Railroad, Kennicott, Valdez-Cordova Census Area, AK

82

33. Coal Fuel Elevator (diagonal in foreground), Fuel Elevator (left), ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

33. Coal Fuel Elevator (diagonal in foreground), Fuel Elevator (left), Fuel Storage Bins (center), and Power Plant (right) Photographs taken by Joseph E.B. Elliot - Huber Coal Breaker, 101 South Main Street, Ashley, Luzerne County, PA

83

2. Building 5 west elevation, showing Building 4 west elevation ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. Building 5 west elevation, showing Building 4 west elevation and stack associated with Building 3 to right. View looking SEE. - John & James Dobson Carpet Mill (West Parcel), Building No. 5, 4041-4055 Ridge Avenue, Philadelphia, Philadelphia County, PA

84

Space Station Tethered Elevator System.  

National Technical Information Service (NTIS)

The optimized conceptual engineering design of a space station tethered elevator is presented. The elevator is an unmanned mobile structure which operates on a ten kilometer tether spanning the distance between the Space Station and a tethered platform. E...

L. A. Anderson

1989-01-01

85

Digital Elevation Models  

USGS Publications Warehouse

The Earth Science Information Center (ESIC) distributes digital cartographic/geographic data files produced by the U.S. Geological Survey (USGS) as part of the National Mapping Program. Digital cartographic data files may be grouped into four basic types. The first of these, called a Digital Line Graph (DLG), is the line map information in digital form. These data files include information on base data categories, such as transportation, hypsography, hydrography, and boundaries. The second type, called a Digital Elevation Model (DEM), consists of a sampled array of elevations for a number of ground positions at regularly spaced intervals. The third type is Land Use and Land Cover digital data which provides information on nine major classes of land use such as urban, agricultural, or forest as well as associated map data such as political units and Federal land ownership. The fourth type, the Geographic Names Information System, provides primary information for all known places, features, and areas in the United States identified by a proper name.

U.S. Geological Survey

1993-01-01

86

The NIAC Space Elevator Program  

Microsoft Academic Search

The NASA Institute for Advanced Concepts (NIAC) has been supporting a space elevator development program to investigate the initial design, deployment and operations scenario. The work has produced a plan for the construction and operation of a small (20 ton capacity) space elevator within the next couple decades. The elevator cable is composed of a carbon nanotube composite extending 100,000

Bradley Carl Edwards

87

A gain-coefficient switched Alexandrite laser  

NASA Astrophysics Data System (ADS)

We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.

Lee, Chris J.; van der Slot, Peter J. M.; Boller, Klaus-J.

2013-01-01

88

Linear Gain - Standard Antennas Below 1000 MHz.  

National Technical Information Service (NTIS)

Gain and antenna parameters related to input impedance are calculated using a computer program called HVD6. The program uses well documented equations to compute these parameters for gain-standard antennas used in relative-gain or gain-transfer measuremen...

R. G. FitzGerrell

1986-01-01

89

The Flynn effect in Korea: Large gains  

Microsoft Academic Search

Secular gains in IQ test scores have been reported for many Western countries. This is the first study of secular IQ gains in South Korea, using various datasets. The first question is what the size of the Flynn effect in South Korea is. The gains per decade are 7.7 points for persons born between 1970 and 1990. These gains on

Jan te Nijenhuis; Sun Hee Cho; Raegan Murphy; Kun Ho Lee

90

Elevated temperature crack growth  

NASA Technical Reports Server (NTRS)

The purpose of this program was to extend the work performed in the base program (CR 182247) into the regime of time-dependent crack growth under isothermal and thermal mechanical fatigue (TMF) loading, where creep deformation also influences the crack growth behavior. The investigation was performed in a two-year, six-task, combined experimental and analytical program. The path-independent integrals for application to time-dependent crack growth were critically reviewed. The crack growth was simulated using a finite element method. The path-independent integrals were computed from the results of finite-element analyses. The ability of these integrals to correlate experimental crack growth data were evaluated under various loading and temperature conditions. The results indicate that some of these integrals are viable parameters for crack growth prediction at elevated temperatures.

Kim, K. S.; Vanstone, R. H.

1992-01-01

91

Elevated temperature biaxial fatigue  

NASA Technical Reports Server (NTRS)

A three year experimental program for studying elevated temperature biaxial fatigue of a nickel based alloy Hastelloy-X has been completed. A new high temperature fatigue test facility with unique capabilities has been developed. Effort was directed toward understanding multiaxial fatigue and correlating the experimental data to the existing theories of fatigue failure. The difficult task of predicting fatigue lives for non-proportional loading was used as an ultimate test for various life prediction methods being considered. The primary means of reaching improved undertanding were through several critical non-proportional loading experiments. It was discovered that the cracking mode switched from primarily cracking on the maximum shear planes at room temperature to cracking on the maximum normal strain planes at 649 C.

Jordan, E. H.

1984-01-01

92

Crown carbon gain and elevated (CO 2 ) responses of understorey saplings with differing allometry and architecture  

Microsoft Academic Search

Summary 1. Attempts at determining the physiological basis of species' differences, such as the ability to grow in deep shade, have been of limited success. However, this basis is fundamental to predicting species' responses to rising atmospheric CO 2 in the forest understorey. We linked a leaf photosynthesis and a tree architecture model to predict the effects of dynamic and

E. NAUMBURG; D. S. ELLSWORTH; R. W. PEARCY

93

Elevated temperature biaxial fatigue  

NASA Technical Reports Server (NTRS)

A 3 year experimental program for studying elevated temperature biaxial fatigue of a nickel based alloy Hastelloy-X has been completed. A new high temperature fatigue test facility with unique capabilities has been developed. Effort was directed toward understanding multiaxial fatigue and correlating the experimental data to the existing theories of fatigue failure. The difficult task of predicting fatigue lives for nonproportional loading was used as an ultimate test for various life prediction methods being considered. The primary means of reaching improved understanding were through several critical nonproportional loading experiments. The direction of cracking observed on failed specimens was also recorded and used to guide the development of the theory. Cyclic deformation responses were permanently recorded digitally during each test. It was discovered that the cracking mode switched from primarily cracking on the maximum shear planes at room temperature to cracking on the maximum normal strain planes at 649 C. In contrast to some other metals, loading path in nonproportional loading had little effect on fatigue lives. Strain rate had a small effect on fatigue lives at 649 C. Of the various correlating parameters the modified plastic work and octahedral shear stress were the most successful.

Jordan, E. H.

1985-01-01

94

Investigation of the gain regimes and gain parameters of the free electron laser dispersion equation  

Microsoft Academic Search

The small signal gain curve and various gain parameters have been computed by solving numerically the generalized gain-dispersion equation of free electron lasers (FEL), which characterizes the conventional magnetic bremsstrahlung FEL, as well as a large number of other FEL devices. The method includes high gain, collective, and axial velocity spread effects, and some waveguide effects. The FEL gain regimes

E. Jerby; A. Gover

1985-01-01

95

Unidirectional high gain brake stop  

NASA Technical Reports Server (NTRS)

This invention relates to a unidirectional high gain brake arrangement that includes in combination a shaft mounted for rotation within a housing. The shaft is rotatable in either direction. A brake is selectively releasably coupled to the housing and to the shaft. The brake has a first member. An intermittent motion device is respectively coupled through the first member to the housing and through a one-way clutch to the shaft. The brake also has a second member that is mechanically coupled to the first brake member and to the housing. The intermittent motion device causes the brake to be activated by movement imparted to the first brake member after a preset number of revolutions of the shaft in one direction. The brake is released by rotation of the shaft in an opposite direction whereby torque transmitted through the one-way clutch to the first brake member is removed.

Lang, David J. (Inventor)

1987-01-01

96

Optical gain in planar waveguides  

NASA Astrophysics Data System (ADS)

Description of optical waveguides is commonly restricted to propagation at distances much larger than the width of the waveguide core and therefore only guided modes are taken into account in theory. Effects connected with leaking of the waves into the substrate may be, however, very important for possible applications in microelectronics. In this paper, we overview our model of photoluminescence of an active planar waveguide and we extend it in order to describe mode formation during propagation in the waveguide. We also include optical amplification into our model and derive formula for description of the Variable Stripe Length (VSL) method widely used for measurement of the net gain coefficient. We demonstrate necessity for corrections of VSL results since their straightforward interpretation may be misleading.

Ostatnický, T.; Janda, P.; Valenta, J.; Pelant, I.

2007-05-01

97

Height Gain, Location Gain, and Correlation in Irregular Terrain at 20, 50, and 100 Mhz.  

National Technical Information Service (NTIS)

Further results on height gain, location gain, and correlation are presented which are based on data obtained from a comprehensive measurement program in irregular terrain at frequencies of 20, 50, and 100 MHz. Specifically, it was found that height gain,...

A. P. Barsis M. J. Miles

1967-01-01

98

High Gain Observer Design for Eth Helicopter  

Microsoft Academic Search

This paper deals with the design of a high gain observer (HGO) for the ETH helicopter laboratory process. The standard format of high gain observer is used and the parameters of the observer are selected in such away that the observer gain matrix H0 becomes Hurwitz. The observer not only estimates the angular positions and velocities of the system but

Naeem Ullah; A. Qayyum Khan; Ghulam Mustafa; M. Yousuf

2006-01-01

99

Modeling gain saturation in neodymium laser glasses  

Microsoft Academic Search

Gain saturation in neodymium laser glasses was modeled using a simplified treatment of the spectroscopic inhomogeneities and experimental parameters obtained from broadband- and laser-excited fluorescence spectroscopy. The predicted large-signal gain behavior for two silicate and two phosphate glasses agrees with measured gain saturation within the experimental uncertainties. The results are extended to treat saturation of other Nd-doped glasses.

D. W. Hall; M. J. Weber

1984-01-01

100

A remote gain control for photomultiplier tubes  

Microsoft Academic Search

Measurements were made on Burle C83062 and Hamamatsu R2497 type photomultiplier tubes (PMTs) to determine an optimum method for remotely controlling their gain. The tubes' gain was varied by three different methods and energy and time measurements were done to determine the tube performance of each method. One method was chosen as optimum for its 10:1 gain range with only

B. E. Williams; D. M. Binkley; M. E. Casey; J. M. Rochelle

1992-01-01

101

Nicotine Replacement: Effects on Postcessation Weight Gain.  

ERIC Educational Resources Information Center

Examined nicotine replacement effects on postcessation weight gain in smoking cessation volunteers. Randomly assigned abstinent subjects to active nicotine or placebo gum conditions for 10 weeks. Analyses revealed strong evidence for gum effect on weight gain, with active gum users gaining mean total of 3.8 pounds compared with 7.8 pounds for…

Gross, Janet; And Others

1989-01-01

102

Determination of optimal gains for constrained controllers  

SciTech Connect

In this report, we consider the determination of optimal gains, with respect to a certain performance index, for state feedback controllers where some elements in the gain matrix are constrained to be zero. Two iterative schemes for systematically finding the constrained gain matrix are presented. An example is included to demonstrate the procedures.

Kwan, C.M.; Mestha, L.K.

1993-08-01

103

Small signal gain in DPAL systems  

Microsoft Academic Search

In this paper we describe a platform for small signal gain measurements for alkali atom laser systems based on the DPAL excitation method. We present initial results that clearly show the transition from absorption on the alkali atom D1 lines in Cs and Rb to optical transparency and positive gain. The achievement of optical gain is critically dependent upon alkali

Kristin L. Galbally-Kinney; Daniel L. Maser; William J. Kessler; Wilson T. Rawlins; Steven J. Davis

2011-01-01

104

78 FR 6745 - Final Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...Elevation in feet (NGVD) + Elevation in feet (NAVD) ...Flooding source(s) elevation above ground Communities affected [caret] Elevation in meters (MSL) modified...upstream of T-303. Marshalls Creek...National Geodetic Vertical...

2013-01-31

105

Achieving yield gains in wheat.  

PubMed

Wheat provides 20% of calories and protein consumed by humans. Recent genetic gains are <1% per annum (p.a.), insufficient to meet future demand. The Wheat Yield Consortium brings expertise in photosynthesis, crop adaptation and genetics to a common breeding platform. Theory suggest radiation use efficiency (RUE) of wheat could be increased ~50%; strategies include modifying specificity, catalytic rate and regulation of Rubisco, up-regulating Calvin cycle enzymes, introducing chloroplast CO(2) concentrating mechanisms, optimizing light and N distribution of canopies while minimizing photoinhibition, and increasing spike photosynthesis. Maximum yield expression will also require dynamic optimization of source: sink so that dry matter partitioning to reproductive structures is not at the cost of the roots, stems and leaves needed to maintain physiological and structural integrity. Crop development should favour spike fertility to maximize harvest index so phenology must be tailored to different photoperiods, and sensitivity to unpredictable weather must be modulated to reduce conservative responses that reduce harvest index. Strategic crossing of complementary physiological traits will be augmented with wide crossing, while genome-wide selection and high throughput phenotyping and genotyping will increase efficiency of progeny screening. To ensure investment in breeding achieves agronomic impact, sustainable crop management must also be promoted through crop improvement networks. PMID:22860982

Reynolds, Matthew; Foulkes, John; Furbank, Robert; Griffiths, Simon; King, Julie; Murchie, Erik; Parry, Martin; Slafer, Gustavo

2012-10-01

106

Gestational weight gain among Hispanic women.  

PubMed

To describe gestational weight gain among Hispanic women and to examine psychological, social, and cultural contexts affecting weight gain. A total of 282 Hispanic women were surveyed post-partum before leaving the hospital. Women were queried about their prepregnancy weight and weight gained during pregnancy. Adequacy of gestational weight gain was based on guidelines set by the Institute of Medicine in 2009. Independent risk factors for excessive or insufficient weight gain were examined by logistic regression. Most women were unmarried (59 %), with a mean age of 28.4 ± 6.6 years and an average weight gain of 27.9 ± 13.3 lbs. Approximately 45 % of women had gained too much, 32 % too little, and only 24 % had an adequate amount of weight gain. The mean birth weight was 7.3, 7.9, and 6.8 lbs among the adequate, excessive, and insufficient weight gain groups. Among women who exercised before pregnancy, two-thirds continued to do so during pregnancy; the mean gestational weight gain of those who continued was lower than those who stopped (26.8 vs. 31.4 lbs, p = 0.04). Independent risk factors for excessive weight gain were being unmarried, U.S. born, higher prepregnancy body mass index, and having indifferent or negative views about weight gain. Independent risk factors for insufficient weight gain were low levels of support and late initiation of prenatal care. Depression, stress, and a woman's or her partner's happiness regarding pregnancy were unrelated to weight gain. The results of this study can be used by prenatal programs to identify Hispanic women at risk for excessive or insufficient gestational weight gain. PMID:23456347

Sangi-Haghpeykar, Haleh; Lam, Kim; Raine, Susan P

2014-01-01

107

The Space Elevator Feasibility Condition  

Microsoft Academic Search

Abstract This paper ties together parameters pertaining to tetherspecific strength and to power system mass density to arrive at an inequality that determines whether a Space Elevator system is viable. The principle for the feasibility condition (FC) is that a Space Elevator must be able to lift its own weight fast enough – fast enough to grow by bootstrapping, fast

Ben Shelef

108

Science on a space elevator  

Microsoft Academic Search

The Space Elevator (SE) represents a major paradigm shift in space access. If the SE's promise of low cost access can be realized, everything becomes economically more feasible to accomplish in space. In this paper we describe in-situ science stations mounted on a science-dedicated space elevator tether. The concept presented here involves a carbon nanotube ribbon that is constructed by

B. E. Laubscher; A. M. Jorgensen

2004-01-01

109

Small signal gain in DPAL systems  

NASA Astrophysics Data System (ADS)

In this paper we describe a platform for small signal gain measurements for alkali atom laser systems based on the DPAL excitation method. We present initial results that clearly show the transition from absorption on the alkali atom D1 lines in Cs and Rb to optical transparency and positive gain. The achievement of optical gain is critically dependent upon alkali cell conditions and collision partners. We also present the first spatially resolved gain measurements in a DPAL system. The small signal gain methods described will be valuable tools for power scaling of these laser systems.

Galbally-Kinney, Kristin L.; Maser, Daniel L.; Kessler, William J.; Rawlins, Wilson T.; Davis, Steven J.

2011-02-01

110

Space Station tethered elevator system  

NASA Technical Reports Server (NTRS)

The optimized conceptual engineering design of a space station tethered elevator is presented. The tethered elevator is an unmanned, mobile structure which operates on a ten-kilometer tether spanning the distance between Space Station Freedom and a platform. Its capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The report discusses the potential uses, parameters, and evolution of the spacecraft design. Emphasis is placed on the elevator's structural configuration and three major subsystem designs. First, the design of elevator robotics used to aid in elevator operations and tethered experimentation is presented. Second, the design of drive mechanisms used to propel the vehicle is discussed. Third, the design of an onboard self-sufficient power generation and transmission system is addressed.

Haddock, Michael H.; Anderson, Loren A.; Hosterman, K.; Decresie, E.; Miranda, P.; Hamilton, R.

1989-01-01

111

Monoamine oxidase inhibitors and weight gain.  

PubMed

Weight gain associated with antidepressant therapy is a common problem that often results in noncompliance. Some authors suggest that monoamine oxidase inhibitors (MAOI) are less likely to produce weight gain than tricyclic antidepressants. This paper addresses the relative potential for weight gain with the MAOI. Assessing the potential for antidepressant-induced weight gain necessitates separating the weight changes associated with alterations in mood disorders from those due to drug-induced alterations in appetite control. The mechanisms of appetite control are reviewed briefly followed by proposed mechanisms by which the MAOI may alter this control. A literature review suggests that phenelzine is the MAOI most likely to induce weight gain; reports of isocarboxazid-induced weight gain are less common. There are no cases of tranylcypromine-induced weight gain in the literature that are clearly associated with the drug. The MAOI probably have different effects on the mechanisms of appetite control. PMID:3068037

Cantú, T G; Korek, J S

1988-10-01

112

Controlling gain one photon at a time  

PubMed Central

Adaptation is a salient property of sensory processing. All adaptational or gain control mechanisms face the challenge of obtaining a reliable estimate of the property of the input to be adapted to and obtaining this estimate sufficiently rapidly to be useful. Here, we explore how the primate retina balances the need to change gain rapidly and reliably when photons arrive rarely at individual rod photoreceptors. We find that the weakest backgrounds that decrease the gain of the retinal output signals are similar to those that increase human behavioral threshold, and identify a novel site of gain control in the retinal circuitry. Thus, surprisingly, the gain of retinal signals begins to decrease essentially as soon as background lights are detectable; under these conditions, gain control does not rely on a highly averaged estimate of the photon count, but instead signals from individual photon absorptions trigger changes in gain. DOI: http://dx.doi.org/10.7554/eLife.00467.001

Schwartz, Gregory W; Rieke, Fred

2013-01-01

113

Effects of local terrain and obstacles upon near horizon gain of L-band beacon antennas  

Microsoft Academic Search

Models are given of the mechanisms that determine the effective gain of an L-band ground based antenna at near horizon elevation angles. Primary emphasis is given to the environment of typical Air Traffic Control Radar Beacon System (ATCRBS) sites.

A. Spiridon

1975-01-01

114

High-Gain, Long-Period Seismograph Station Installation Report, Eilat, Israel.  

National Technical Information Service (NTIS)

The report describes the installation of a high-gain, long-period seismograph system at Eilat, Israel. The station is located at 29.33 degrees North latitude, 34.57 degrees East longitude at an elevation of about 200 m above sea level in the same tunnel a...

T. L. Johnson

1971-01-01

115

Estimated Effect of the Teacher Advancement Program on Student Test Score Gains  

ERIC Educational Resources Information Center

This article presents findings from the first independent, third-party appraisal of the impact of the Teacher Advancement Program (TAP) on student test score gains in mathematics. TAP is a comprehensive school reform model designed to attract highly effective teachers, improve instructional effectiveness, and elevate student achievement. We use a…

Springer, Matthew G.; Ballou, Dale; Peng, Art

2014-01-01

116

High-gain observers in the presence of measurement noise: A nonlinear gain approach  

Microsoft Academic Search

This paper studies a high-gain observer with a nonlinear gain. The nonlinearity is chosen to have a higher observer gain during the transient period and a lower gain afterwards, thus overcoming the tradeoff between fast state reconstruction and measurement noise attenuation. The observer is designed such that the behavior of the innovation process can be controlled separately from the other

Alexis Amanda Ball; Hassan K. Khalil

2008-01-01

117

Elevation Derivatives for National Applications  

USGS Publications Warehouse

The Elevation Derivatives for National Applications (EDNA) project is a multi-agency effort to develop standard topographically derived layers for use in hydrologic and environmental modeling. The EDNA takes advantage of the seamless and filtered characteristics for the National Elevation Dataset (NED) to create a hydrologically conditioned Digital Elevation Model (DEM) useful for modeling applications. The goals of the project are to create a hydrologically conditioned DEM and systematically extract a set of standard derivatives that can be used to facilitate data integration with other U.S. Geological Survey (USGS) framework data sets such as the National Hydrography Dataset (NHD) and the Watershed Boundaries Dataset (WBD).

Geological Survey (U.S.)

2005-01-01

118

Actinide Thermodynamics at Elevated Temperatures  

SciTech Connect

The postclosure chemical environment in the proposed Yucca Mountain repository is expected to experience elevated temperatures. Predicting migration of actinides is possible if sufficient, reliable thermodynamic data on hydrolysis and complexation are available for these temperatures. Data are scarce and scattered for 25 degrees C, and nonexistent for elevated temperatures. This collaborative project between LBNL and PNNL collects thermodynamic data at elevated temperatures on actinide complexes with inorganic ligands that may be present in Yucca Mountain. The ligands include hydroxide, fluoride, sulfate, phosphate and carbonate. Thermodynamic parameters of complexation, including stability constants, enthalpy, entropy and heat capacity of complexation, are measured with a variety of techniques including solvent extraction, potentiometry, spectrophotometry and calorimetry

Friese, Judah I.; Rao, Linfeng; Xia, Yuanxian; Bachelor, Paula P.; Tian, Guoxin

2007-11-16

119

Microchannel plate modal gain variations with temperature  

NASA Technical Reports Server (NTRS)

Measurements of the modal gain of two high-gain curved-channel microchannel plates (MCPs) at various operating temperatures are presented. Both MCPs were fabricated from the Long Life glass with 12-micron diam channels on 15-micron centers. The modal gain was found to decrease with increasing temperature at a rate of -0.1 percent C. This reduction of gain with temperature is attributed primarily to an axial temperature gradient along each MCP channel creating a nonuniform electric field within the channel that lowers the effective output gain. A lowering of the secondary electron yield resulting from increased phonon scattering of secondary electrons released within the walls of the MCP channels was assessed, but was found to have a negligible contribution to the drop in gain with temperature.

Slater, David C.; Timothy, J. G.

1993-01-01

120

Space Elevator: Path to Space  

NASA Astrophysics Data System (ADS)

The Space Elevator is the most promising Space Transportation system on the drawing boards today, combining scalability, qualify of ride, and safety to deliver truly commercial-grade space access-practically comparable to a train ride to space.

Kaushal, A. K.

2012-05-01

121

Space Elevators Preliminary Architectural View  

NASA Astrophysics Data System (ADS)

Space Systems Architecture has been expanded into a process by the US Department of Defense for their large scale systems of systems development programs. This paper uses the steps in the process to establishes a framework for Space Elevator systems to be developed and provides a methodology to manage complexity. This new approach to developing a family of systems is based upon three architectural views: Operational View OV), Systems View (SV), and Technical Standards View (TV). The top level view of the process establishes the stages for the development of the first Space Elevator and is called Architectural View - 1, Overview and Summary. This paper will show the guidelines and steps of the process while focusing upon components of the Space Elevator Preliminary Architecture View. This Preliminary Architecture View is presented as a draft starting point for the Space Elevator Project.

Pullum, L.; Swan, P. A.

122

ConcepTest: Elevated Terraces  

NSDL National Science Digital Library

A series of elevated terraces (former wave-cut platforms) along an active plate boundary coast is evidence for ______________. a. Sea level rise b. Uplift of continental crust c. Subsidence (sinking) of crust

123

Space Elevator Base Leg Architecture  

NASA Astrophysics Data System (ADS)

While the Space Elevator stretches for 104,000 kilometers, the region of most concern, from the survival perspective, is 2,500 kms and below. The threats inside this dangerous arena include debris, spacecraft, meteorites, lightening, winds, rogue waves, aircraft, and intentional human acts. Two major questions will be addressed that will influence the overall systems architecture of a Space Elevator. While the deployment phase of the development of the Space Elevator will only have a single ribbon from the surface of the Earth to well beyond the Geosynchronous altitude, a mature Space Elevator must never allow a complete sever of the system. Design approaches, materials selections, international policy development and assembly must ensure that the integrity of the Space Elevator be maintained. The trade space analysis will address the probability of an individual ribbon being severed, the length of time to repair, and the potential for a catastrophic Space Elevator cut. The architecture proposed for the base leg portion will address two questions: Shall there be multiple base legs to 2,500 kms altitude? And Should the anchor be based on land or at sea?

Swan, C.; Swan, P. A.

124

Error margin for antenna gain measurements  

NASA Technical Reports Server (NTRS)

The specification of measured antenna gain is incomplete without knowing the error of the measurement. Also, unless gain is measured many times for a single antenna or over many identical antennas, the uncertainty or error in a single measurement is only an estimate. In this paper, we will examine in detail a typical error budget for common antenna gain measurements. We will also compute the gain uncertainty for a specific UHF horn test that was recently performed on the Jet Propulsion Laboratory (JPL) antenna range. The paper concludes with comments on these results and how they compare with the 'unofficial' JPL range standard of +/- ?.

Cable, V.

2002-01-01

125

Expected ICESat measurement of glacier elevation change  

Microsoft Academic Search

The Ice, Cloud, and land Elevation Satellite (ICESat), part of NASA's Earth Observing System, was launched on 01-12-03. ICESat will measure, among other things, ice sheet elevations and changes in elevation through time [{Zwally et al.,} 2002]. ICESat elevation profiles will consist of the centroid elevations of {symbol{\\

D. Mitchell; J. Sauber; D. Harding; C. Carabajal; W. Krabill; S. Manizade; J. Bufton

2003-01-01

126

Etude d'un multiplicateur a galettes de microcanaux a gain eleve et presentant de tres faibles fluctuations statistiques de gain. (Study of a high gain microchannel plate photomultiplier having low statistical gain fluctuations).  

National Technical Information Service (NTIS)

A new photomultiplier configuration which synthesizes the performances of several models is proposed. The principles of microchannel plate photomultipliers are reviewed. The physical phenomena which limit the electron multiplication process in a microchan...

M. Audier

1980-01-01

127

Elevated CO2 enhances biological contributions to elevation change in coastal wetlands by offsetting stressors associated with sea-level rise  

USGS Publications Warehouse

1. Sea-level rise, one indirect consequence of increasing atmospheric CO2, poses a major challenge to long-term stability of coastal wetlands. An important question is whether direct effects of elevated CO 2 on the capacity of marsh plants to accrete organic material and to maintain surface elevations outweigh indirect negative effects of stressors associated with sea-level rise (salinity and flooding). 2. In this study, we used a mesocosm approach to examine potential direct and indirect effects of atmospheric CO2 concentration, salinity and flooding on elevation change in a brackish marsh community dominated by a C3 species, Schoenoplectus americanus, and a C4 grass, Spartina patens. This experimental design permitted identification of mechanisms and their role in controlling elevation change, and the development of models that can be tested in the field. 3. To test hypotheses related to CO2 and sea-level rise, we used conventional anova procedures in conjunction with structural equation modelling (SEM). SEM explained 78% of the variability in elevation change and showed the direct, positive effect of S. americanus production on elevation. The SEM indicated that C3 plant response was influenced by interactive effects between CO2 and salinity on plant growth, not a direct CO2 fertilization effect. Elevated CO2 ameliorated negative effects of salinity on S. americanus and enhanced biomass contribution to elevation. 4. The positive relationship between S. americanus production and elevation change can be explained by shoot-base expansion under elevated CO 2 conditions, which led to vertical soil displacement. While the response of this species may differ under other environmental conditions, shoot-base expansion and the general contribution of C3 plant production to elevation change may be an important mechanism contributing to soil expansion and elevation gain in other coastal wetlands. 5. Synthesis. Our results revealed previously unrecognized interactions and mechanisms contributing to marsh elevation change, including amelioration of salt stress by elevated CO2 and the importance of plant production and shoot-base expansion for elevation gain. Identification of biological processes contributing to elevation change is an important first step in developing comprehensive models that permit more accurate predictions of whether coastal marshes will persist with continued sea-level rise or become submerged. ?? 2008 The Authors.

Cherry, J. A.; McKee, K. L.; Grace, J. B.

2009-01-01

128

GaInNAs Laser Gain.  

National Technical Information Service (NTIS)

The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of ...

W. E. Chow E. D. Jones N. A. Modine S. R. Kurtz A. A. Allerman

2000-01-01

129

Teacher predictions versus actual student gains  

NSDL National Science Digital Library

Presents a study where astronomy teachers (n=66) try to predict student (n=330) outcomes on astronomy and related topics pre- and posttest. Suggested findings include a course in astronomy did not result in an overall knowledge gain, teachers fared well at predicting prior student knowledge, and teachers vastly overestimated student gain in knowledge during the course.

Sadler, Philip M.; Lightman, Alan

2005-10-27

130

GaInNAs laser gain  

SciTech Connect

The optical gain spectra for GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of the lasing threshold current density of GaInNAs/GaAs quantum well structures.

CHOW,WENG W.; JONES,ERIC D.; MODINE,NORMAND A.; KURTZ,STEVEN R.; ALLERMAN,ANDREW A.

2000-05-23

131

Gain scheduling: potential hazards and possible remedies  

Microsoft Academic Search

Current gain scheduling control of nonlinear practice is limited to slow variations in the scheduling variable. These limitations are revealed to be consequences of fundamental control concepts. It is shown how a reformulation of the gain scheduling procedure can lead to the ultimate removal of these restrictions

Jeff S. Shamma; Michael Athans

1992-01-01

132

Meaningful Reading Gains by Adult Literacy Learners  

ERIC Educational Resources Information Center

To obtain a fuller picture of the efficacy of reading instruction programs for adult literacy learners, gains by individual students were examined in a sample (n = 148) in which weak to moderate gains at the group level had been obtained in response to tutoring interventions that focused on strengthening basic decoding and fluency skills of low…

Scarborough, Hollis S.; Sabatini, John P.; Shore, Jane; Cutting, Laurie E.; Pugh, Kenneth; Katz, Leonard

2013-01-01

133

Gain Margins of Adaptive Control Systems  

Microsoft Academic Search

This paper presents a systematic study of the gain margins (GM) of adaptive control systems: the specification of the parameter range of a control gain matrix in a designed adaptive control system for maintaining the desired closed-loop signal boundedness and asymptotic tracking performance. It is proved that the GM is infinity for continuous-time direct model reference adaptive control (MRAC) schemes

Qian Sang; Gang Tao

2010-01-01

134

Weight gain associated with valproate in childhood  

Microsoft Academic Search

Weight gain is a common side effect of valproate treatment. Several mechanisms have been suggested for its pathophysiology; of these, impairment of beta-oxidation of fatty acids and increased insulin secretion have been supported by clinical studies. To investigate whether changes in carnitine and insulin levels had a role in the weight gain occurring with valproate treatment in children, 20 patients

Ercan Demir; Sabiha Aysun

2000-01-01

135

Can Free Trade Guarantee Gains from Trade?  

Microsoft Academic Search

Static and dynamic gains from trade are the reasons why countries embark on the path of free trade, expecting this to promote industrialization and development. There is nothing, however, in the conventional theory of international trade that guarantees that these gains will materialize and even if they do, they may not accelerate industrialization and growth. This is because there are

Moritz Cruz

2008-01-01

136

77 FR 74610 - Final Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...in feet (NGVD) + Elevation in feet (NAVD...Communities affected elevation above ground [caret] Elevation in meters (MSL...Geodetic Vertical Datum. + North American...with +708 City of Marshall, North Fork...

2012-12-17

137

Elevated CO2 effects on plant carbon, nitrogen, and water relations: six important lessons from FACE.  

PubMed

Plant responses to the projected future levels of CO(2) were first characterized in short-term experiments lasting days to weeks. However, longer term acclimation responses to elevated CO(2) were subsequently discovered to be very important in determining plant and ecosystem function. Free-Air CO(2) Enrichment (FACE) experiments are the culmination of efforts to assess the impact of elevated CO(2) on plants over multiple seasons and, in the case of crops, over their entire lifetime. FACE has been used to expose vegetation to elevated concentrations of atmospheric CO(2) under completely open-air conditions for nearly two decades. This review describes some of the lessons learned from the long-term investment in these experiments. First, elevated CO(2) stimulates photosynthetic carbon gain and net primary production over the long term despite down-regulation of Rubisco activity. Second, elevated CO(2) improves nitrogen use efficiency and, third, decreases water use at both the leaf and canopy scale. Fourth, elevated CO(2) stimulates dark respiration via a transcriptional reprogramming of metabolism. Fifth, elevated CO(2) does not directly stimulate C(4) photosynthesis, but can indirectly stimulate carbon gain in times and places of drought. Finally, the stimulation of yield by elevated CO(2) in crop species is much smaller than expected. While many of these lessons have been most clearly demonstrated in crop systems, all of the lessons have important implications for natural systems. PMID:19401412

Leakey, Andrew D B; Ainsworth, Elizabeth A; Bernacchi, Carl J; Rogers, Alistair; Long, Stephen P; Ort, Donald R

2009-01-01

138

Tether Elevator Crawler Systems (TECS)  

NASA Technical Reports Server (NTRS)

One of the needs of the experimenters on the space station is access to steady and controlled-variation microgravity environments. A method of providing these environments is to place the experiment on a tether attached to the space station. This provides a high degree of isolation from structural oscillations and vibrations. Crawlers can move these experiments along the tethers to preferred locations, much like an elevator. This report describes the motion control laws developed for these crawlers and the testing of laboratory models of these tether elevator crawlers.

Swenson, Frank R.

1987-01-01

139

Analysis of a Space Elevator  

NASA Astrophysics Data System (ADS)

This paper investigates the engineering principles that govern the design of a Space Elevator. The presentation includes extensive mathematical analysis of several basic approaches, reviews historical approaches and looks at some novel implementations. The technical challenges that must be overcome and the potential application of new technology to meet these challenges are discussed. While the paper focuses on the engineering aspects of the space elevator concept, some space is devoted to the potential use and benefit of a successful implementation. The primary objective of this paper is to show that no fundamental physical principles preclude the concept, but that technology development is required before a practical implementation can be realized.

Langston, J. L.

2003-12-01

140

Controlling gain one photon at a time.  

PubMed

Adaptation is a salient property of sensory processing. All adaptational or gain control mechanisms face the challenge of obtaining a reliable estimate of the property of the input to be adapted to and obtaining this estimate sufficiently rapidly to be useful. Here, we explore how the primate retina balances the need to change gain rapidly and reliably when photons arrive rarely at individual rod photoreceptors. We find that the weakest backgrounds that decrease the gain of the retinal output signals are similar to those that increase human behavioral threshold, and identify a novel site of gain control in the retinal circuitry. Thus, surprisingly, the gain of retinal signals begins to decrease essentially as soon as background lights are detectable; under these conditions, gain control does not rely on a highly averaged estimate of the photon count, but instead signals from individual photon absorptions trigger changes in gain. DOI:http://dx.doi.org/10.7554/eLife.00467.001. PMID:23682314

Schwartz, Gregory W; Rieke, Fred

2013-01-01

141

High gain observer with updated gain for a class of MIMO nonlinear systems  

Microsoft Academic Search

A high gain like observer with an updated gain is proposed for a class of MIMO nonlinear systems that are observable for any inputs. The main contribution of this article lies in the nature of the observer gain that involves a scalar time-varying design parameter governed by some scalar Riccati equation. This time-varying design parameter, chosen constant in standard high

M. Farza; M. Oueder; R. Ben Abdennour; M. MSaad

2011-01-01

142

20 CFR 220.141 - Substantial gainful activity, defined.  

Code of Federal Regulations, 2013 CFR

...2012-04-01 true Substantial gainful activity, defined. 220.141 Section 220.141...DETERMINING DISABILITY Substantial Gainful Activity § 220.141 Substantial gainful activity, defined. Substantial gainful...

2013-04-01

143

Poor Weight Gain in Infants and Children (Beyond the Basics)  

MedlinePLUS

... calorie fortifiers PI POOR WEIGHT GAIN OVERVIEW During infancy and childhood, children gain weight and grow more ... Weight gain normally follows a predictable course from infancy through adolescence. However, some children do not gain ...

144

Defense of a space elevator  

Microsoft Academic Search

The Space Elevator (SE) represents a major paradigm shift in space access. If the SE's promise of low-cost access is to be realized, everything becomes economically more feasible to accomplish in space. In this paper we describe a defensive system of the SE. The primary scenario adopted for this analysis is the SE based on a floating platform in the

Laubscher

2004-01-01

145

Analysis of a Space Elevator  

Microsoft Academic Search

This paper investigates the engineering principles that govern the design of a Space Elevator. The presentation includes extensive mathematical analysis of several basic approaches, reviews historical approaches and looks at some novel implementations. The technical challenges that must be overcome and the potential application of new technology to meet these challenges are discussed. While the paper focuses on the engineering

J. L. Langston

2003-01-01

146

Space elevator systems level analysis  

Microsoft Academic Search

The Space Elevator (SE) represents a major paradigm shift in space access. It involves new, untried technologies in most of its subsystems. Thus the successful construction of the SE requires a significant amount of development, This in turn implies a high level of risk for the SE. This paper will present a systems level analysis of the SE by subdividing

Laubscher

2004-01-01

147

Gain bandwidth characterization of surface-emitting quantum well laser gain structures for femtosecond operation.  

PubMed

We present a method to experimentally characterize the gain filter and calculate a corresponding parabolic gain bandwidth of lasers that are described by "class A" dynamics by solving the master equation of spectral condensation for Gaussian spectra. We experimentally determine the gain filter, with an equivalent parabolic gain bandwidth of up to 51 nm, for broad-band InGaAs/GaAs quantum well gain surface-emitting semiconductor laser structures capable of producing pulses down to 60 fs width when mode-locked with an optical Stark saturable absorber mirror. PMID:20941029

Barnes, M E; Mihoubi, Z; Wilcox, K G; Quarterman, A H; Farrer, I; Ritchie, D A; Garnache, A; Hoogland, S; Apostolopoulos, V; Tropper, A C

2010-09-27

148

Experience Matters: Information Acquisition Optimizes Probability Gain  

PubMed Central

Deciding which piece of information to acquire or attend to is fundamental to perception, categorization, medical diagnosis, and scientific inference. Four statistical theories of the value of information—information gain, Kullback-Liebler distance, probability gain (error minimization), and impact—are equally consistent with extant data on human information acquisition. Three experiments, designed via computer optimization to be maximally informative, tested which of these theories best describes human information search. Experiment 1, which used natural sampling and experience-based learning to convey environmental probabilities, found that probability gain explained subjects’ information search better than the other statistical theories or the probability-of-certainty heuristic. Experiments 1 and 2 found that subjects behaved differently when the standard method of verbally presented summary statistics (rather than experience-based learning) was used to convey environmental probabilities. Experiment 3 found that subjects’ preference for probability gain is robust, suggesting that the other models contribute little to subjects’ search behavior.

Nelson, Jonathan D.; McKenzie, Craig R.M.; Cottrell, Garrison W.; Sejnowski, Terrence J.

2010-01-01

149

High-gain magnetized inertial fusion.  

PubMed

Magnetized inertial fusion (MIF) could substantially ease the difficulty of reaching plasma conditions required for significant fusion yields, but it has been widely accepted that the gain is not sufficient for fusion energy. Numerical simulations are presented showing that high-gain MIF is possible in cylindrical liner implosions based on the MagLIF concept [S. A. Slutz et al Phys. Plasmas 17, 056303 (2010)] with the addition of a cryogenic layer of deuterium-tritium (DT). These simulations show that a burn wave propagates radially from the magnetized hot spot into the surrounding much denser cold DT given sufficient hot-spot areal density. For a drive current of 60 MA the simulated gain exceeds 100, which is more than adequate for fusion energy applications. The simulated gain exceeds 1000 for a drive current of 70 MA. PMID:22324693

Slutz, Stephen A; Vesey, Roger A

2012-01-13

150

High-Gain Magnetized Inertial Fusion  

NASA Astrophysics Data System (ADS)

Magnetized inertial fusion (MIF) could substantially ease the difficulty of reaching plasma conditions required for significant fusion yields, but it has been widely accepted that the gain is not sufficient for fusion energy. Numerical simulations are presented showing that high-gain MIF is possible in cylindrical liner implosions based on the MagLIF concept [S. A. Slutz et al Phys. Plasmas 17, 056303 (2010)PHPAEN1070-664X10.1063/1.3333505] with the addition of a cryogenic layer of deuterium-tritium (DT). These simulations show that a burn wave propagates radially from the magnetized hot spot into the surrounding much denser cold DT given sufficient hot-spot areal density. For a drive current of 60 MA the simulated gain exceeds 100, which is more than adequate for fusion energy applications. The simulated gain exceeds 1000 for a drive current of 70 MA.

Slutz, Stephen A.; Vesey, Roger A.

2012-01-01

151

Organic Causes of Weight Gain and Obesity  

MedlinePLUS

... gain an ounce, and which kids face a lifelong struggle to keep their weight in check. Insulin ... Urinary Tract Head Neck & Nervous System Heart Infections Learning Disabilities Obesity Orthopedic Prevention Sexually Transmitted Skin Tobacco ...

152

Integrated High-Gain Active Radar Augmentor.  

National Technical Information Service (NTIS)

A compact and integrated high-gain radar augmented system, including: a cylindrical microstrip receive antenna mounted on a cylinder for providing nominal omni-directional coverage, a transmit antenna similar to the receive antenna mounted on the same cyl...

J. M. DeVries

1983-01-01

153

'Breast Milk Banks' Gain in Popularity  

MedlinePLUS

... on this page, please enable JavaScript. 'Breast Milk Banks' Gain in Popularity Experts say they're safer ... News) -- A wave of new nonprofit breast milk banks are opening across North America, driven by research ...

154

Numerical differentiation using high-gain observers  

Microsoft Academic Search

High-gain observers have been used in nonlinear control to estimate the derivatives of the output. In this paper, we study discrete-time implementation of high-gain observers and their use as numerical differentiators. We show that discretization using the bilinear transformation method gives results better than other discretization methods. We also show that many of the available numerical differentiators are special cases

Ahmed Dabroom; H. K. Khalil

1997-01-01

155

Gain saturation in phosphate laser glasses  

Microsoft Academic Search

Saturation of gain at 1053 nm was studied in seven Nd-doped phosphate glasses. Values of saturation fluence measured with 1.4-ns pulses were slightly less than those measured with 20-ns pulses. At both pulse lengths, saturation fluence increased with output fluence. For the seven glasses, the product of saturation fluence and gain cross section was constant to within +6 percent.

S. M. Yarema; D. Milam

1982-01-01

156

Context-specific adaptation of saccade gain  

NASA Technical Reports Server (NTRS)

Previous studies established that vestibular reflexes can have two adapted states (e.g., gain) simultaneously, and that a context cue (e.g., vertical eye position) can switch between the two states. The present study examined this phenomenon of context-specific adaptationfor horizontal saccades, using a variety of contexts. Our overall goal was to assess the efficacy of different context cues in switching between adapted states. A standard double-step paradigm was used to adapt saccade gain. In each experiment, we asked for a simultaneous gain decrease in one context and gain increase in another context, and then determined if a change in the context would invoke switching between the adapted states. Horizontal eye position worked well as a context cue: saccades with the eyes deviated to the right could be made to have higher gains while saccades with the eyes deviated to the left could be made to have lower gains. Vertical eye position was less effective. This suggests that the more closely related a context cue is to the response being adapted, the more effective it is. Roll tilt of the head, and upright versus supine orientations, were somewhat effective in context switching; these paradigms contain orientation of gravity with respect to the head as part of the context.

Shelhamer, Mark; Clendaniel, Richard A.

2002-01-01

157

Exponential Tethers for Accelerated Space Elevator Deployment  

Microsoft Academic Search

An exponential space elevator is a space elevator with a tether cross-section that varies exponentially with altitude. With such an elevator it is possible to reel in tether material at one end of the elevator while reeling out at the other end, without changing the overall taper prole. I show how to use this property to build up or clone

Blaise Gassendy

158

ST elevation without myocardial infarction.  

PubMed

Acute myocarditis may mimic myocardial infarction because the affected patients report 'classical' chest pain; the ECG changes and echocardiography are identical to those observed in acute coronary syndromes, and serum markers are increased. We describe a case with ST segment elevation on admission ECG, and coronary angiography was normal. Cardiac magnetic resonance with myocardial delayed enhancement sequences is a non-invasive alternative for diagnosing myocarditis. PMID:24711464

Bitar, Zouheir Ibrahim; Swede, Mohammad; Almerri, Khaled

2014-01-01

159

Tapered InAs/InGaAs quantum dot semiconductor optical amplifier design for enhanced gain and beam quality.  

PubMed

In this Letter, a design for a tapered InAs/InGaAs quantum dot semiconductor optical amplifier is proposed and experimentally evaluated. The amplifier's geometry was optimized in order to reduce gain saturation effects and improve gain efficiency and beam quality. The experimental measurements confirm that the proposed amplifier allows for an elevated optical gain in the saturation regime, whereas a five-fold increase in the coupling efficiency to a standard single mode optical fiber is observed, due to the improvement in the beam quality factor M² of the emitted beam. PMID:23939062

Mesaritakis, Charis; Kapsalis, Alexandros; Simos, Hercules; Simos, Christos; Krakowski, Michel; Krestnikov, Igor; Syvridis, Dimitris

2013-07-15

160

Gain and energy storage in holmium YLF  

NASA Technical Reports Server (NTRS)

It is demonstrated that Q-switched holmium lasers are capable of high-gain and high-energy operation at 300 K. Small-signal gain coefficients of 0.50 and 0.12/cm have been measured in YLF and YAG, respectively. Small-signal gains of 0.50/cm are comparable to those achievable in Nd:YAG and are not typical of low-gain materials. This large gain in the Ho:YLF material is made possible by operating the amplifier in the ground state depletion mode. The amplifier performance data and associated analysis presented demonstrate that efficient energy storage is possible with very high excited state ion densities of the Ho 5I7 upper laser level. This is an important result since upconversion can limit the 5I7 population. Although upconversion was still present in this experiment, it was possible to achieve efficient energy storage, demonstrating that the problem is manageable even at high excitation densities in YLF.

Storm, Mark E.; Deyst, John P.

1991-01-01

161

High-gain 1310-nm reflective semiconductor optical amplifiers with low-gain uncertainty  

Microsoft Academic Search

A 1310-nm reflective semiconductor optical amplifier with a gain uncertainty of only 0.8 dB at an average gain level of over 30 dB has been demonstrated using a microoptic polarization reversing retroreflector. For this amplifier 3-dB saturation output powers of up to 10 dBm and a noise figure of 7.5 dB have been obtained. A low gain uncertainty for undefined

L. F. Tiemeijer; G. N. van den Hoven; P. J. A. Thijs; T. van Dongen; J. J. M. Binsma; E. J. Jansen; A. J. M. Verboven

1997-01-01

162

Pressure-gain combustion for gas turbines  

SciTech Connect

As part of the Department of Energy`s Advanced Gas Turbine Systems Program, an investigation has been performed to evaluate {open_quotes}pressure-gain{close_quotes} combustion systems for gas turbine applications. Results from the investigation have shown that, due to the oscillatory combustion process, a pressure boost can be achieved for suitable combustor geometries. The pressure gains achieved thus far have been as high as 1 percent. It has also been shown that for some combustor designs operating under typical gas turbine conditions, NO{sub x} and CO emissions are about 30 ppmv and 8 ppmv, respectively. It is believed that with optimized designs, further improvements in both pressure gain and emissions may be possible. We have concluded that this technology remains a candidate for improving the efficiency of a gas turbine while reducing pollutant emissions.

Gemmen, R.; Richards, G.; Janus, M.

1995-12-01

163

Neutron intensity gains for converging guide systems  

NASA Astrophysics Data System (ADS)

Neutron focusing, or increased current density at the expense of increased beam divergence, can be obtained by the addition of a converging guide at the end of a straight guide. The greatest gains are achieved when the critical angle of the coating of the converging guide is much greater than that of the straight guide. The gain is limited, however, by the increase in angle that the neutron trajectory makes with the axis upon successive reflections. Acceptance diagrams are used for deriving analytical expressions for describing the transmission properties of such systems. The results can be reduced to nine basic formulae depending on the geometric configuration and the coatings of the guides. A graphical method is presented for determining the appropriate expression for the current density gain for a particular guide configuration and relative surface coatings, as a function of wavelength. The results are in agreement with earlier measurements obtained with a straight-converging guide system.

Mildner, D. F. R.

1991-03-01

164

Gain Narrowing in Few-Atom Systems  

SciTech Connect

Using a density matrix approach, we study the simplest systems that display both gain and feedback: clusters of 2 to 5 atoms, one of which is pumped. The other atoms supply feedback through multiple scattering of light. We show that, if the atoms are in each other's near field, the system exhibits large gain narrowing and spectral mode redistribution. The observed phenomena are more pronounced if the feedback is enhanced. Our system is to our knowledge the simplest exactly solvable microscopic system which shows the approach to laser oscillation.

Savels, Tom [FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam (Netherlands); Mosk, Allard P. [Complex Photonic Systems, MESA Research Institute, University of Twente, Post Office Box 217, 7500 AE Enschede (Netherlands); Lagendijk, Ad [FOM Institute for Atomic and Molecular Physics, Kruislaan 407, 1098 SJ, Amsterdam (Netherlands); Complex Photonic Systems, MESA Research Institute, University of Twente, Post Office Box 217, 7500 AE Enschede (Netherlands)

2007-03-09

165

High-gain MOS tunnel emitter transistors  

NASA Astrophysics Data System (ADS)

Tunnel emitter transistors (TETs) are promising devices for high-current-density, high-frequency applications. The excellent CMOS compatibility of the TET makes it an ideal candidate to replace the bipolar junction transistors in BiCMOS technology; however, many properties of the TET are still under investigation. In this paper we present TETs with the highest current gain ever reported, 500-800. The effect of oxide quality on device performance is also described, and how the device characteristics can be improved by post-metallization annealing. Finally, we observe enhanced gain due to collector-emitter avalanching.

Aderstedt, Erik; Medugorac, Igor; Lundgren, Per

2002-04-01

166

An ISS small gain theorem for general networks  

Microsoft Academic Search

We provide a generalized version of the nonlinear small gain theorem for the case of more than two coupled input-to-state stable systems. For this result the interconnection gains are described in a nonlinear gain matrix, and the small gain condition requires bounds on the image of this gain matrix. The condition may be interpreted as a nonlinear generalization of the

Sergey Dashkovskiy; Björn S. Rüffer; Fabian R. Wirth

2007-01-01

167

Elevation forces and resilience of the sinus membrane during sinus floor elevation: preliminary measurements using a balloon method on ex vivo pig heads.  

PubMed

Purpose: Because the maxilla and its alveolar process are prone to resorption after tooth loss, it is often necessary to perform a bone augmentation procedure to successfully carry out implant treatment in that region. The aim of this study was to determine the adhesive force between the sinus membrane and the osseous sinus floor that occurs during sinus floor elevation with a balloon lift system. Materials and Methods: Twenty-two ex vivo pig heads were used for this study. Access to the maxillary sinus was gained via the lateral sinus wall. Sinus elevation was performed using an inflatable balloon, which was consecutively filled with 3 mL of a radiopaque fluid. Pressure was monitored directly and continuously during the elevation procedure with an electronic pressure gauge. The integrity of the membrane was checked microscopically and macroscopically. Results: The average adhesion force of the sinus membrane was found to be 748 ± 65.56 mmHg. On microscopic and macroscopic inspection, no mucosal tearing occurred during sinus floor elevation. Underwood septa, when present, did not significantly influence the adhesion forces. Conclusions: The balloon system allowed for reproducible real-time measurement of the elevation forces and soft tissue resilience of the sinus membrane during the elevation process in this animal model. No mucosal ruptures were caused with this technical setup, in which effective elevation pressure ranging from 660 to 880 mmHg was not exceeded. A possible transfer of this technical setup to clinical procedures in humans requires investigation. PMID:24818193

Stelzle, Florian; Rohde, Maximilian

2014-01-01

168

On the performance of high-gain observers with gain adaptation under measurement noise  

Microsoft Academic Search

We address the problem of state observation for a system whose dynamics may involve poorly known, perhaps even nonlocally Lipschitz functions and whose output measurement may be corrupted by noise. It is known that one way to cope with all these uncertainties and noise is to use a high-gain observer with a gain adapted on-line. The proposed method, while presented

Ricardo G. Sanfelice; Laurent Praly

2011-01-01

169

High-gain observers in the presence of measurement noise: A switched-gain approach  

Microsoft Academic Search

This paper considers output feedback control using high-gain observers in the presence of measurement noise for a class of nonlinear systems. We study stability in the presence of measurement noise and illustrate the tradeoff when selecting the observer gain between state reconstruction speed and robustness to model uncertainty on the one hand versus amplification of noise on the other. Based

Jeffrey H. Ahrens; Hassan K. Khalil

2009-01-01

170

Water Quality in Gaines Creek and Gaines Creek Arm of Eufaula Lake, Oklahoma.  

National Technical Information Service (NTIS)

Based on samples collected from May 1978 to May 1980 and analyzed for major anions, nitrogen, trace elements, phytoplankton, and bacteria, the water in Gaines Creek and the Gaines Creek arm of Eufaula Lake was similar with respect to suitability for munic...

J. K. Kurklin

1990-01-01

171

High gain observers based on immersion technics  

Microsoft Academic Search

The high gain observer based on normal forms is initially proposed in. These normal forms characterize single input uniformly observable systems (systems which are observable independently on the input). Next, in, this observable normal form together with observer synthesis have been extended to a class of MIMO nonlinear systems by assuming that some regular flag of co-distribution does not depend

Hassan Hammouri; Basil Ucchueddu

2010-01-01

172

GAIN Appraisal Program IV. Fourth Report.  

ERIC Educational Resources Information Center

The Greater Avenues for Independence (GAIN) legislation in California mandated a full range of employment-related training and supportive services designed to provide welfare program applicants and recipients with the skills needed to acquire unsubsidized employment through education and training. Tests to assess the basic reading, mathematics,…

Simon, June; And Others

173

Adaptive Filtering Algorithms with Automatic Gain Control.  

National Technical Information Service (NTIS)

In this paper we introduce an automatic gain control (AGC) scheme for adaptive algorithms that are used extensively in many applications. The proposed AGC scheme is realized by using an estimate of the cross correlation between adaptive error and the inpu...

T. J. Shan T. Kailath

1985-01-01

174

The High Gain Free Electron Lasers  

Microsoft Academic Search

This dissertation is composed of two independent parts on a theoretical study of the high gain free electron laser. In the first part (Chapters 2-4) a non-linear (saturation) regime of the free electron lasers (FELs) with electromagnetic wigglers is described. Two opposite configurations for the wiggler field propagation direction are considered in a unified manner. The wiggler field propagating counter

Yoonho Seo; Yoonho

1989-01-01

175

High gain flux compression generator fabrication issues  

Microsoft Academic Search

The fabrication issues involved with a high gain helical flux compression generator are discussed. The generator is 20 cm in diameter, 76 cm long, contains 4500 gm of explosives, and its desired output is 2 million amperes into a 200-nH load. The goal is to attain better than 1000 X current multiplication. To achieve this goal great attention must be

J. L. Cutting; D. K. Abe; J. B. Chase; R. S. Hawke; P. A. Pincosy; H. T. Takemori; M. L. Fillipucci

1989-01-01

176

Women's Gains at Risk in Afghanistan.  

National Technical Information Service (NTIS)

M. Ashraf Haidari describes the gains Afghan women have made since the Taliban government ended 7 years ago. They have regained most of the freedoms they lost under the Taliban, and the Afghan government under President Karzai is committed to furthering t...

M. A. Haidari

2008-01-01

177

Gain without inversion in semiconductor nanostructures  

Microsoft Academic Search

When Einstein showed that light amplification needed a collection of atoms in `population inversion' (that is, where more than half the atoms are in an excited state, ready to emit light rather than absorb it) he was using thermodynamic arguments. Later on, quantum theory predicted that matter-wave interference effects inside the atoms could, in principle, allow gain without inversion (GWI).

M. D. Frogley; J. F. Dynes; M. Beck; J. Faist; C. C. Phillips

2006-01-01

178

Locus of Cognitive Gains from Tutoring.  

ERIC Educational Resources Information Center

An experiment was conducted to determine whether tutoring is a learning activity from which the tutor, as well as the tutee, gains cognitively. Undergraduate students (N=80) participated in the study. Half of the subjects studied selected material to tutor another subject. The other half studied material to prepare for a test that they would take.…

McKellar, Nancy A.

179

Automatic gain control for Raman lidar signals  

Microsoft Academic Search

Electronic component improvements allow everyone to use them for performing new features in different applications. Lidar signal control is matter of continuous design and it can be studied in order to increase signal-to-noise ratio. Fortunately, the advent, of programmable gain amplifiers, switching capacitor filters and specific AD converters, is the stimulus of improving lidar signal quality. The main scope of

Aimé Lay-Ekuakille; Giuseppe Vendramin; Amerigo Trotta

2008-01-01

180

Quantum well lasers - Gain, spectra, dynamics  

Microsoft Academic Search

The present consideration of theoretical and experimental issues in the field of quantum well laser development emphasizes the basic behavior of such aspects of laser operation as the gain, the field spectrum, and the modulation dynamics. The use of quantum well structures is noted to yield improvements in these properties, and brings several novel concepts to bear on the field

Y. Arakawa; A. Yariv

1986-01-01

181

Gain-assisted superluminal light propagation  

Microsoft Academic Search

Einstein's theory of special relativity and the principle of causality imply that the speed of any moving object cannot exceed that of light in a vacuum (c). Nevertheless, there exist various proposals for observing faster-than- c propagation of light pulses, using anomalous dispersion near an absorption line, nonlinear and linear gain lines, or tunnelling barriers. However, in all previous experimental

L. J. Wang; A. Kuzmich; A. Dogariu

2000-01-01

182

Sudden Gains during Therapy of Social Phobia  

ERIC Educational Resources Information Center

The present study investigated the phenomenon of sudden gains in 107 participants with social phobia (social anxiety disorder) who received either cognitive-behavioral group therapy or exposure group therapy without explicit cognitive interventions, which primarily used public speaking situations as exposure tasks. Twenty-two out of 967…

Hofmann, Stefan G.; Schultz, Stefan M.; Meuret, Alicia E.; Moscovitch, David A.; Suvak, Michael

2006-01-01

183

Weight Gain during Pregnancy: Reexamining the Guidelines.  

National Technical Information Service (NTIS)

Since 1990, the last time the Institute of Medicine (IOM) released guidelines for weight gain during pregnancy, many key aspects of the health of women of childbearing age have changed. This population now includes a higher proportion of women from racial...

A. L. Yaktine K. M. Rasmussen

2009-01-01

184

Pole assignment by gain output feedback  

Microsoft Academic Search

This short paper deals with the problem of pole assignment with incomplete state observation. It is shown that if the system is controllable and observable, and ifn leq r + m - 1, an almost arbitrary set of distinct closed-loop poles is assignable by gain output feedback, wheren, r, andmare the numbers of state variables, inputs and outputs, respectively. This

H. Kimura

1975-01-01

185

Harvesting Energy from the Counterbalancing (Weaving) Movement in Bicycle Riding  

PubMed Central

Bicycles are known to be rich source of kinetic energy, some of which is available for harvesting during speedy and balanced maneuvers by the user. A conventional dynamo attached to the rim can generate a large amount of output power at an expense of extra energy input from the user. However, when applying energy conversion technology to human powered equipments, it is important to minimize the increase in extra muscular activity and to maximize the efficiency of human movements. This study proposes a novel energy harvesting methodology that utilizes lateral oscillation of bicycle frame (weaving) caused by user weight shifting movements in order to increase the pedaling force in uphill riding or during quick speed-up. Based on the 3D motion analysis, we designed and implemented the prototype of an electro-dynamic energy harvester that can be mounted on the bicycle's handlebar to collect energy from the side-to-side movement. The harvester was found to generate substantial electric output power of 6.6 mW from normal road riding. It was able to generate power even during uphill riding which has never been shown with other approaches. Moreover, harvesting of energy from weaving motion seems to increase the economy of cycling by helping efficient usage of human power.

Yang, Yoonseok; Yeo, Jeongjin; Priya, Shashank

2012-01-01

186

78 FR 9600 - Final Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...Elevation in feet (NGVD) + Elevation in feet (NAVD) Flooding source(s) Location of referenced Depth in feet Communities...of Great Bend. Approximately 1.2 miles +1036 upstream of Steam Hollow Road. Dundaff...

2013-02-11

187

Repeatability of elevation measurements: Apollo photography  

NASA Technical Reports Server (NTRS)

Sun elevation angle effects on repeatability, using Apollo 15 photographs are analyzed and results extended to slope related effects. Preliminary results indicate repeatibility of elevation measurement is related to contrast in the stereoscopic image.

Wu, S. S. C.; Schafer, F. J.; Nakata, G. M.; Jordon, R.

1973-01-01

188

Diffusion rates for elevated releases  

SciTech Connect

A search of the literature related to diffusion from elevated sources has determined that an adequate data base exists for use in developing parameterizations for estimating diffusion rates for material released from free standing stacks at nuclear power plants. A review of published data analyses indicates that a new parameterization of horizontal diffusion rates specifically for elevated releases is not likely to significantly change the magnitudes of horizontal diffusion coefficients on the average. However, the uncertainties associated with horizontal diffusion coefficient estimates under any given set of atmospheric conditions could be reduced by a new parameterization. Similarly, a new parameterization of vertical diffusion rates would be unlikely to significantly alter the magnitudes of diffusion coefficients for unstable atmospheric conditons. However, for neutral and stable atmospheric conditions, a new parameterization of vertical diffusion rates might increase vertical diffusion coefficients significantly. The increase would move ground-level time-integrated concentration maxima closer to the plant and would increase the maxima. 55 references, 2 figures, 4 tables.

Ramsdell, J.V.

1983-11-01

189

Approach to managing elevated creatinine.  

PubMed Central

OBJECTIVE: To describe a systematic approach to finding the underlying cause of an elevated creatinine level. QUALITY OF EVIDENCE: This diagnostic approach is based on a synthesis of information from reference works on nephrology, articles found through a MEDLINE search, and the author's personal experience. MAIN MESSAGE: Elevated creatinine levels suggest the differential diagnosis of renal failure (RF). History and a complete physical examination are important, keeping in mind that RF is often asymptomatic in the early stages. After repeating the creatinine test to verify results, baseline tests should be ordered to identify the cause of the RF. Comparing results of serial tests is essential for determining whether RF is acute or chronic, stable or progressive. An ultrasound scan is particularly useful for eliminating an obstructive cause; the size of the kidney can indicate whether disease is acute or chronic. Complementary blood tests and imaging studies might be useful. CONCLUSION: Diagnosing and managing RF can appear complex, but a systematic approach will help you find the cause and treat the condition.

Tremblay, Richard

2004-01-01

190

18 CFR 11.13 - Energy gains calculations.  

Code of Federal Regulations, 2010 CFR

...ACT Charges for Headwater Benefits § 11.13 Energy gains calculations. (a...application of the Headwater Benefits Energy Gains Model, as presented in The Headwater Benefits Energy Gains (HWBEG) Model...

2010-04-01

191

18 CFR 11.13 - Energy gains calculations.  

Code of Federal Regulations, 2010 CFR

...ACT Charges for Headwater Benefits § 11.13 Energy gains calculations. (a...application of the Headwater Benefits Energy Gains Model, as presented in The Headwater Benefits Energy Gains (HWBEG) Model...

2009-04-01

192

Why we need a space elevator  

Microsoft Academic Search

The goals of and vision for development of a space elevator have been discussed repeatedly. However, why we should develop one has been glossed over. This paper will focus upon the major issue—why build a space elevator infrastructure? It considers why we need a space elevator, what missions it would enable and how far it would reduce costs. There is

Cathy W. Swan; Peter A. Swan

2006-01-01

193

Hurricane Katrina sediment slowed elevation loss in subsiding brackish marshes of the Mississippi River delta  

USGS Publications Warehouse

Although hurricanes can damage or destroy coastal wetlands, they may play a beneficial role in reinvigorating marshes by delivering sediments that raise soil elevations and stimulate organic matter production. Hurricane Katrina altered elevation dynamics of two subsiding brackish marshes in the Mississippi River deltaic plain by adding 3 to 8 cm of sediment to the soil surface in August 2005. Soil elevations at both sites subsequently declined due to continued subsidence, but net elevation gain was still positive at both Pearl River (+1.7 cm) and Big Branch (+0.7 cm) marshes two years after the hurricane. At Big Branch where storm sediments had higher organic matter and water contents, post-storm elevation loss was more rapid due to initial compaction of the storm layer in combination with root-zone collapse. In contrast, elevation loss was slower at Pearl River where the storm deposit (high sand content) did not compact and the root zone did not collapse. Vegetation at both sites fully recovered within one year, and accumulation of root matter at Big Branch increased 10-fold from 2005 to 2006, suggesting that the hurricane stimulated belowground productivity. Results of this study imply that hurricane sediment may benefit subsiding marshes by slowing elevation loss. However, long-term effects of hurricane sediment on elevation dynamics will depend not only on the amount of sediment deposited, but on sediment texture and resistance to compaction as well as on changes in organic matter accumulation in the years following the hurricane.

McKee, K. L.; Cherry, J. A.

2009-01-01

194

[Unexplained, subclinical chronically elevated transaminases].  

PubMed

Unexplained, subclinical chronically elevated transaminases is mainly a marker of non-alcoholic fatty liver disease, metabolic syndrome, alcoholism and diabetes, which are very common situations but viral hepatitis and iatrogenic origin must also be considered. Before looking for hepatic or genetic rare diseases, it is worth considering hypertransaminasemia as a clue for muscular disease, particularly in paediatric settings, and creatine phosphokinase is a specific marker. Then, patient history, examination and appropriate biologic requests can permit the identification of less frequent disorders where isolated hypertransaminasemia is possibly the unique marker of the disease for a long while: hemochromatosis, celiac disease, autoimmune hepatitis, Wilson's disease, ?1-anti-trypsine deficiency, thyroid dysfunctions, Addison's disease. Liver biopsy should be performed only in patients with aspartate aminotransferases upper the normal range or alanine aminotransferases higher than twice the normal range after 6 months delay with dietetic corrections. PMID:23623710

Vital Durand, D; Lega, J-C; Fassier, T; Zenone, T; Durieu, I

2013-08-01

195

Magnetization dynamics at elevated temperatures  

NASA Astrophysics Data System (ADS)

The conventional Landau-Lifshitz (LL) equation is the basis for simulation of magnetic structure and dynamics as long as the temperature is not too close to Curie temperature. In order to model the magnetization dynamics at elevated temperatures, one needs to extend the LL equation by including a finite longitudinal relaxation. Here within the self-consistent mean-field treatment of ferromagnetism, we propose an effective equation which is capable of addressing magnetization dynamics for a wide range of temperatures. At low temperatures, the equation reduces to the Landau-Lifshitz equation, namely, the transverse relaxation governs the dynamics. At high temperatures, it reduces to paramagnetic Block equation. Near the Curie temperature, the longitudinal relaxations play a more important role on the magnetization reversal. We present numerical calculations to simulate a heat-assisted-magnetic-recording process when the temperature is heated and cooled through the Curie temperature.

Xu, Lei; Zhang, Shufeng

2012-02-01

196

Elevation Map of Kathmandu, Nepal  

NASA Technical Reports Server (NTRS)

These Shuttle Radar Topgraphy Mission (SRTM) images show the basin of Kathmandu, the capital of Nepal: On the left a detail (27 km x 20.5 km) of the X-SAR digital elevation model (shown below), on the right the corresponding radar amplitude image. The amplitude is a measure of the backscattering of the transmitted microwaves. In the amplitude image the 'Bagmati-River' is visible south of the city center and the international Airport in the eastern part. The runway appears as a dark stripe. The airport is infamous for its difficult landing/takeoff conditions due to the close vicinity of the surrounding high mountains. For more information and a image of the region around Kathmandu, visit the German Remote Sensing Data Center SRTM Treasure Vault. Image courtesy German Remote Sensing Data Center

2002-01-01

197

NOVA: A Nanotube Space Elevator  

NSDL National Science Digital Library

This 5-minute video adapted from NOVA scienceNOW explores the potential of carbon nanotubes, whose strength and unique properties make them useful for a variety of applications. See animations of how carbon atoms bond to one another in different ways to make diamond, graphite, buckyballs, and nanotubes. Consider how a seemingly impossible application, such as an elevator from the surface of Earth to space, is now theoretically possible given this revolutionary new building material. Hosted by Neil Degrasse Tyson. Editor's Note: Carbon nanotubes are members of the fullerene structural family, which includes buckyballs. They are the strongest material yet discovered in terms of tensile strength, though product development is still in its infancy. The potential applications for carbon nanotubes are impressive, especially in fibers, electrical circuits, optics, and medicine. This resource includes background information for teachers and suggested discussion questions.

2011-08-19

198

RAGE Control: Regulate and Gain Emotional Control.  

PubMed

Advances in neurobiology and computer science make possible interventions designed to strengthen basic processes behind emotional control. We present one such computer-based intervention, RAGE Control (Regulate And Gain Emotional Control). This extends the usual paradigm of biofeedback by requiring relaxation in the midst of engaging executive processes in a quick reaction task. RAGE Control teaches children to simultaneously focus, react, inhibit impulses, and keep their heart rate down in the context of a traditional space battle game. The program is grounded in the theory of Cognitive Behavioral Therapy and is currently in clinical use by psychotherapists at Children's Hospital in Boston. It aims to reduce the need for psychotropic medication to help children gain emotional control. Clinical trials to test the promise of this technology are warranted. PMID:19745492

Kahn, Jason; Ducharme, Peter; Travers, Brian; Gonzalez-Heydrich, Joseph

2009-01-01

199

Metamaterials driven by gain and special configurations  

NASA Astrophysics Data System (ADS)

Negative phase velocity materials are engineered media that are currently enjoying a surge of interest due to their interesting properties and potential applications, through negative refraction, to achieve cloaking that makes things invisible. The literature is alive with papers devoted to the design of suitable metamaterials and there is a particular desire to operate at THz frequencies and above. A full theory of gain control up to the THz frequency range is presented together with a comprehensive study of diffraction-managed solitons. There are aspects of control that can be achieved through externally imposed influences such as gyroelectromagnetic effects. Nonlinear behaviour is also intrinsic to the Holy Grail quest for complete control, coupled to the possibility of beneficial competition between damping and gain.

Boardman, A. D.; King, N.; Rapoport, Yu.

2007-06-01

200

Contrast Gain Control Model Fits Masking Data  

NASA Technical Reports Server (NTRS)

We studied the fit of a contrast gain control model to data of Foley (JOSA 1994), consisting of thresholds for a Gabor patch masked by gratings of various orientations, or by compounds of two orientations. Our general model includes models of Foley and Teo & Heeger (IEEE 1994). Our specific model used a bank of Gabor filters with octave bandwidths at 8 orientations. Excitatory and inhibitory nonlinearities were power functions with exponents of 2.4 and 2. Inhibitory pooling was broad in orientation, but narrow in spatial frequency and space. Minkowski pooling used an exponent of 4. All of the data for observer KMF were well fit by the model. We have developed a contrast gain control model that fits masking data. Unlike Foley's, our model accepts images as inputs. Unlike Teo & Heeger's, our model did not require multiple channels for different dynamic ranges.

Watson, Andrew B.; Solomon, Joshua A.; Null, Cynthia H. (Technical Monitor)

1994-01-01

201

Mispredicting the Hedonic Benefits of Segregated Gains  

Microsoft Academic Search

The hedonic benefit of a gain (e.g., receiving $100) may be increased by segregating it into smaller units that are distributed over time (e.g., receiving $50 on each of 2 days). However, if these units are too small (e.g., receiving 1¢ on each of 10,000 days), they may fall beneath the person's hedonic limen and have no hedonic benefit at

Carey K. Morewedge; Daniel T. Gilbert; Boaz Keysar; Michael J. Berkovits; Timothy D. Wilson

2007-01-01

202

Mispredicting the Hedonic Benefits of Segregated Gains  

ERIC Educational Resources Information Center

The hedonic benefit of a gain (e.g., receiving $100) may be increased by segregating it into smaller units that are distributed over time (e.g., receiving $50 on each of 2 days). However, if these units are too small (e.g., receiving 1 cent on each of 10,000 days), they may fall beneath the person's hedonic limen and have no hedonic benefit at…

Morewedge, Carey K.; Gilbert, Daniel T.; Keysar, Boaz; Berkovits, Michael J.; Wilson, Timothy D.

2007-01-01

203

Optoacoustic Raman gain spectroscopy of liquids  

Microsoft Academic Search

We report the first optoacoustic Raman gain spectroscopy (OARS) of liquids, using two synchronized pulsed dye lasers, and gated optoacoustic detection of the energy deposited in the liquid due to the stimulated Raman (Stokes) scattering. We demonstrate this sensitive technique with several neat liquids, including benzene, acetone, 1,1,1-trichloroethane, toluene, and n-hexane. This technique seems competitive or superior to other techniques

C. K. N. Patel; A. C. Tam

1979-01-01

204

Fuzzy Gain Scheduling for Flight Control Laws  

Microsoft Academic Search

The state-of-the-art methodology for the design of digital flight-by-wire flight control laws is based on dimming and linearization of a nonlinear aircraft model at selected operating points and subsequent tuning of linear control laws. Despite recent advances in the development of computer-aided control design toots, selection of the operating points and the design of the gain schedule still has to

Marcel Oosterom; Robert Babuska

2001-01-01

205

Coherence Related Gain Phenomena in Potassium -  

Microsoft Academic Search

This work focuses on the theoretical and experimental investigations of coherence related gain phenomena in a collisionally assisted, four-level Raman-driven system, where atomic collisions provide incoherent population to the probed excited state. The theory, as originally envisioned by Narducci and coworkers(1) (without collisions), is first introduced and discussed. Modifications to this theory are made to allow for the addition of

Jeffrey A. Kleinfeld

1995-01-01

206

The Comstar D/3 gain degradation experiment  

NASA Technical Reports Server (NTRS)

The results of gain degradation measurements using the Comstar D/3 19.04 GHz beacon are reported. This experiment utilized 0.6 and 5 m aperture antennas aligned along the same propagation path to examine propagation effects which are related to the antenna aperture size. Sample data for clear air, scintillation in clear air, and precipitation fading are presented. Distributions of the received signal levels and variances for both antennas are also presented.

Lee, T. C.; Hodge, D. B.

1981-01-01

207

[Against CRRT: hybrid treatments are gaining ground].  

PubMed

Renal replacement therapies (RRT) are a key component of the therapeutic approach to acute kidney injury in the ICU. They are usually performed as intermittent hemodialysis (IHD) or continuous RRT (CRRT). Each of these therapies has its advantages and disadvantages. The so-called ''hybrid'' therapies have been gaining popularity in recent years. This kind of treatment, known as ''sustained low-efficiency dialysis'' or SLED, has most of the advantages of IHD and CRRT, without sharing their disadvantages and limitations. PMID:19255960

Basile, C

2009-01-01

208

Etiology and therapeutic approach to elevated lactate  

PubMed Central

Lactate levels are commonly evaluated in acutely ill patients. Although most commonly used in the context of evaluating shock, lactate can be elevated for many reasons. While tissue hypoperfusion is probably the most common cause of elevation, many other etiologies or contributing factors exist. Clinicians need to be aware of the many potential causes of lactate elevation as the clinical and prognostic importance of an elevated lactate varies widely by disease state. Moreover, specific therapy may need to be tailored to the underlying cause of elevation. The current review is based on a comprehensive PubMed search and contains an overview of the pathophysiology of lactate elevation followed by an in-depth look at the varied etiologies, including medication-related causes. The strengths and weaknesses of lactate as a diagnostic/prognostic tool and its potential use as a clinical endpoint of resuscitation will be discussed. The review ends with some general recommendations on management of patients with elevated lactate.

Andersen, Lars W.; Mackenhauer, Julie; Roberts, Jonathan C.; Berg, Katherine M.; Cocchi, Michael N.; Donnino, Michael W.

2014-01-01

209

Effects of Gain Changes on RPM Performance  

SciTech Connect

The mission of the U.S. Department of Energy/National Nuclear Security Administration's (DOE/NNSA's) Office of the Second Line of Defense (SLD) is to strengthen the capability of foreign governments to deter, detect, and interdict the illicit trafficking of special nuclear and other radioactive materials across international borders and through the global maritime shipping system. The goal of this mission is to reduce the probability of these materials being fashioned into a weapon of mass destruction or radiological dispersal device that could be used against the United States or its international partners. This goal is achieved primarily through the installation and operation of radiation detection equipment at border crossings, airports, seaports, and other strategic locations around the world. In order to effectively detect the movement of radioactive material, the response of these radiation detectors to various materials in various configurations must be well characterized. Oak Ridge National Laboratory (ORNL) investigated two aspects of Radiation Portal Monitor (RPM) settings, based on a preliminary investigation done by the Los Alamos National Laboratory (LANL): source-to-detector distance effect on amplifier gain and optimized discriminator settings. This report discusses this investigation. A number of conclusions can be drawn from the ORNL testing. First, for increased distance between the source and the detector, thus illuminating the entire detector rather than just the center of the detector (as is done during detector alignments), an increase in gain may provide a 5-15% increase in sensitivity (Fig. 4). However, increasing the gain without adjusting the discriminator settings is not recommended as this makes the monitor more sensitive to electronic noise and temperature-induced fluctuations. Furthermore, if the discriminators are adjusted in relation to the increase in gain, thus appropriately discriminating against electronic noise, the sensitivity gains are less than 5% (Fig. 6). ORNL does not consider this slight increase in sensitivity to be a worthwhile pursuit. Second, increasing the ULD will increase sensitivity a few percent (Fig. 7); however, it is not clear that the slight increase in sensitivity is worth the effort required to make the change (e.g., reliability, cost, etc.). Additionally, while the monitor would be more sensitive to HEU, it would also be more sensitive to NORM. Third, the sensitivity of the system remains approximately the same whether it is calibrated to a small source on contact or a large source far away (Fig. 6). This affirms that no changes to the existing calibration procedure are necessary.

Lousteau, Angela L [ORNL; York, Robbie Lynn [ORNL; Livesay, Jake [ORNL

2012-03-01

210

ICESat Estimates of Elevation and Volume Changes of Greenland Ice Caps  

NASA Astrophysics Data System (ADS)

ICESat Laser Altimetry acquired over the period 2003-2008 has been processed to provide estimates of changes in elevation for each aligned laser footprint. These are then interpolated, geographically, yielding estimates of volume change on nearly two dozen peripheral ice caps, mostly located in northern Greenland. Definition of ice cap edges are provided by the Greenland Mapping Project 90m, high-resolution, ice mask (GIMP). The results provide a geometric measure of sub-decadal ice cap gain or loss, with the outcome being that more ice caps are losing volume than gaining. Ice caps ranging in size from 200 to 7500 square km have been considered. Over the five-years, ice cap volume changes range from -1.586 cubic km for the Ikke Opmålt cap (2965.1 sq. km areal extent) to +0.582 cubic km on the Kronprins Christian Land cap (7414.6 sq. km). The corresponding averaged rates of elevation change range from -0.535 m/yr to +0.079 m/yr, respectively. Estimates of elevation changes from variations in the rate of firn compaction are also applied. Additionally, examination of time histories of ICESat elevation profiles crossing select ice caps reveal seasonal losses and gains.

Robbins, J. W.; Zwally, J.; Yi, D.; Li, J.; Saba, J. L.

2012-12-01

211

Updating the gain of global finite-time high gain observers  

Microsoft Academic Search

Recently, new results about semi-global and global finite-time observation have been obtained by the use of continuous high gain observers. In this paper, we propose to extend these results by studying “time-varying high gain” observers and by providing new update laws: first, we adapt the law introduced by L. Praly in the case of asymptotic observation to the finite-time case

Laurent Burlion; Tarek Ahmed-Ali; Francoise Lamnabhi-Lagarrigue

2011-01-01

212

Boreal feather mosses secrete chemical signals to gain nitrogen.  

PubMed

The mechanistic basis of feather moss-cyanobacteria associations, a main driver of nitrogen (N) input into boreal forests, remains unknown. Here, we studied colonization by Nostoc sp. on two feather mosses that form these associations (Pleurozium schreberi and Hylocomium splendens) and two acrocarpous mosses that do not (Dicranum polysetum and Polytrichum commune). We also determined how N availability and moss reproductive stage affects colonization, and measured N transfer from cyanobacteria to mosses. The ability of mosses to induce differentiation of cyanobacterial hormogonia, and of hormogonia to then colonize mosses and re-establish a functional symbiosis was determined through microcosm experiments, microscopy and acetylene reduction assays. Nitrogen transfer between cyanobacteria and Pleurozium schreberi was monitored by secondary ion mass spectrometry (SIMS). All mosses induced hormogonia differentiation but only feather mosses were subsequently colonized. Colonization on Pleurozium schreberi was enhanced during the moss reproductive phase but impaired by elevated N. Transfer of N from cyanobacteria to their host moss was observed. Our results reveal that feather mosses likely secrete species-specific chemo-attractants when N-limited, which guide cyanobacteria towards them and from which they gain N. We conclude that this signalling is regulated by N demands of mosses, and serves as a control of N input into boreal forests. PMID:23795916

Bay, Guillaume; Nahar, Nurun; Oubre, Matthieu; Whitehouse, Martin J; Wardle, David A; Zackrisson, Olle; Nilsson, Marie-Charlotte; Rasmussen, Ulla

2013-10-01

213

Prepregnancy body mass index, gestational weight gain and the likelihood of major depression during pregnancy  

PubMed Central

Objective We assessed the relation between prepregnancy body mass index (BMI) and the likelihood of major depressive disorder (MDD) during pregnancy and test whether this association was modified by gestational weight gain. Method Women (n=242) were enrolled at <20 weeks gestation into a prospective cohort study. Diagnosis of MDD was made with the Structured Clinical Interview for DSM-IV at 20, 30, and 36 weeks. Gestational weight gain was compared with the 1990 Institute of Medicine weight gain recommendations. To assess the independent association between prepregnancy BMI and the odds of MDD, MDD at each time point was used as the dependent measure in a multivariable longitudinal logistic regression model employing generalized estimating equations. Results There was a strong, positive dose-response association between prepregnancy BMI and the likelihood of MDD (p=0.002). Compared with a BMI of 18, the adjusted odds ratios (95% confidence interval) for BMIs of 23, 28, and 33 were 1.4 (1.1, 1.7), 1.9 (1.3, 2.9), and 2.6 (1.4, 4.3), respectively. Gestational weight gain significantly modified this effect. Among women with weight gains within and above the 1990 IOM recommendations, pregravid overweight was associated with a greater likelihood of major depression. In contrast, all women with weight gains below recommended levels had an elevated odds of depression, regardless of their pregravid BMI (p<0.05). Conclusions Because pregravid overweight, poor gestational weight gain, and major depression all pose substantial risks for fetal development and birth outcomes, health care providers should monitor depression levels in these women to facilitate appropriate depression intervention.

Bodnar, Lisa M.; Wisner, Katherine L.; Moses-Kolko, Eydie; Sit, Dorothy K.Y.; Hanusa, Barbara H.

2009-01-01

214

Development of hyperinsulinemia and insulin resistance during the early stage of weight gain.  

PubMed

Obesity is associated with insulin resistance and hyperinsulinemia, which is considered to be a core component in the pathophysiology of obesity-related comorbidities. As yet it is unknown whether insulin resistance and hyperinsulinemia already develop during weight gain within the normal range. In 10 healthy male subjects the effect of intentional weight gain by 2 BMI points was examined on insulin. C-peptide and glucose levels following a meal, 75 g of glucose, and a two-step hyperglycemic clamp increased plasma glucose by 1.38 and 2.75 mmol/l, respectively. Baseline insulin, C-peptide, and glucose concentrations were significantly higher after weight gain from 21.8 to 23.8 kg/m(2) BMI within 4(1/2) mo. Calculations of insulin secretion and clearance indicate that reduced insulin clearance contributes more to post-weight gain basal hyperinsulinemia than insulin secretion. Following oral or intravenous stimulation insulin concentrations were significantly higher post-weight gain during all three test conditions, whereas C-peptide and glucose levels did not differ. Calculations of insulin secretion and clearance demonstrated that higher stimulated insulin concentrations are entirely due to clearance but not secretion. Despite significantly higher insulin levels, the rate of intravenous glucose required to maintain the defined elevation of glucose levels was either identical (1.38 mmol/l) or even significantly lower (2.75 mmol/l) following weight gain. The present study demonstrates for the first time that insulin resistance already develops during weight gain within the normal range of body weight. The associated basal and stimulated hyperinsulinemia is the result of differentiated changes of insulin secretion and clearance, respectively. PMID:18171910

Erdmann, Johannes; Kallabis, Bianca; Oppel, Ulrich; Sypchenko, Oleg; Wagenpfeil, Stefan; Schusdziarra, Volker

2008-03-01

215

Addressing women's concerns about weight gain due to smoking cessation  

Microsoft Academic Search

Specific concerns about weight gain following smoking cessation inhibit attempts to quit smoking, especially in women. However, adjunct interventions to prevent weight gain after cessation have generally been successful only in attenuating, rather than preventing, weight gain. More aggressive weight control adjuncts may be necessary to prevent cessation-induced weight gain. On the other hand, weight control programs have not been

Kenneth A. Perkins; Michele D. Levine; Marsha D. Marcus; Saul Shiffman

1997-01-01

216

Modal analysis of a planar waveguide with gain and losses  

Microsoft Academic Search

In this study, we analyze the waveguiding properties of a planar waveguide amplifier in which losses and gain can be present simultaneously. It is found that the subsequent modes comprise both loss and gain modes. Also, the dependence of the gain on the state of polarization turns out to be significant for realistic dielectric structures. For strong losses or gain,

T. D. Visser; H. Blok; D. Lenstra

1995-01-01

217

Gain calculation for Er\\/Yb-doped fiber amplifiers  

Microsoft Academic Search

Gain and output power as a function of pump power has been calculated for short Er\\/Yb doped single mode fibers for various fiber parameters. The calculation shows (i) small signal gain increases with increasing Er concentration, (ii) long fiber lengths provide both higher gain and higher output, (iii) calculated gain is larger for higher Er emission cross section, and, (iv)

Qiang Wang; Robert G. Ahrens; Niloy K. Dutta

2004-01-01

218

Dynamic multibody modeling for tethered space elevators  

NASA Astrophysics Data System (ADS)

This paper presents a fundamental modeling strategy for dealing with powered and propelled bodies moving along space tethers. The tether is divided into a large number of discrete masses, which are connected by viscoelastic springs. The tether is subject to the full range of forces expected in Earth orbit in a relatively simple manner. Two different models of the elevator dynamics are presented. In order to capture the effect of the elevator moving along the tether, the elevator dynamics are included as a separate body in both models. One model treats the elevator's motion dynamically, where propulsive and friction forces are applied to the elevator body. The second model treats the elevator's motion kinematically, where the distance along the tether is determined by adjusting the lengths of tether on either side of the elevator. The tether model is used to determine optimal configurations for the space elevator. A modal analysis of two different configurations is presented which show that the fundamental mode of oscillation is a pendular one around the anchor point with a period on the order of 160 h for the in-plane motion, and 24 h for the out-of-plane motion. Numerical simulation results of the effects of the elevator moving along the cable are presented for different travel velocities and different elevator masses.

Williams, Paul

2009-08-01

219

The space station tethered elevator system  

NASA Technical Reports Server (NTRS)

The optimized conceptual engineering design of a space station tethered elevator is presented. The elevator is an unmanned mobile structure which operates on a ten kilometer tether spanning the distance between the Space Station and a tethered platform. Elevator capabilities include providing access to residual gravity levels, remote servicing, and transportation to any point along a tether. The potential uses, parameters, and evolution of the spacecraft design are discussed. Engineering development of the tethered elevator is the result of work conducted in the following areas: structural configurations; robotics, drive mechanisms; and power generation and transmission systems. The structural configuration of the elevator is presented. The structure supports, houses, and protects all systems on board the elevator. The implementation of robotics on board the elevator is discussed. Elevator robotics allow for the deployment, retrieval, and manipulation of tethered objects. Robotic manipulators also aid in hooking the elevator on a tether. Critical to the operation of the tethered elevator is the design of its drive mechanisms, which are discussed. Two drivers, located internal to the elevator, propel the vehicle along a tether. These modular components consist of endless toothed belts, shunt-wound motors, regenerative power braking, and computer controlled linear actuators. The designs of self-sufficient power generation and transmission systems are reviewed. Thorough research indicates all components of the elevator will operate under power provided by fuel cells. The fuel cell systems will power the vehicle at seven kilowatts continuously and twelve kilowatts maximally. A set of secondary fuel cells provides redundancy in the unlikely event of a primary system failure. Power storage exists in the form of Nickel-Hydrogen batteries capable of powering the elevator under maximum loads.

Anderson, Loren A.

1989-01-01

220

Operational Amplifier with Two-Stage Gain-Boost  

Microsoft Academic Search

In this paper we present a three-stage fully differential operational amplifier in 120nm digital CMOS. To reach high gain gain-boosted cascodes in the first stage are used. The gain-boost amplifiers are realized as two-stage amplifiers with self cascodes. A DC gain of 108dB and an unity-gain frequency of 1.06GHz are achieved at 1.2V supply. The operational amplifier is appropriate for

FRANZ SCHLÖGL; HORST DIETRICH; HORST ZIMMERMANN

2006-01-01

221

Semiconductor radiation detector with internal gain  

DOEpatents

An avalanche drift photodetector (ADP) incorporates extremely low capacitance of a silicon drift photodetector (SDP) and internal gain that mitigates the surface leakage current noise of an avalanche photodetector (APD). The ADP can be coupled with scintillators such as CsI(Tl), NaI(Tl), LSO or others to form large volume scintillation type gamma ray detectors for gamma ray spectroscopy, photon counting, gamma ray counting, etc. Arrays of the ADPs can be used to replace the photomultiplier tubes (PMTs) used in conjunction with scintillation crystals in conventional gamma cameras for nuclear medical imaging.

Iwanczyk, Jan (Los Angeles, CA); Patt, Bradley E. (Sherman Oaks, CA); Vilkelis, Gintas (Westlake Village, CA)

2003-04-01

222

Neuronal Plasticity: Increasing the Gain in Pain  

NASA Astrophysics Data System (ADS)

We describe those sensations that are unpleasant, intense, or distressing as painful. Pain is not homogeneous, however, and comprises three categories: physiological, inflammatory, and neuropathic pain. Multiple mechanisms contribute, each of which is subject to or an expression of neural plasticity-the capacity of neurons to change their function, chemical profile, or structure. Here, we develop a conceptual framework for the contribution of plasticity in primary sensory and dorsal horn neurons to the pathogenesis of pain, identifying distinct forms of plasticity, which we term activation, modulation, and modification, that by increasing gain, elicit pain hypersensitivity.

Woolf, Clifford J.; Salter, Michael W.

2000-06-01

223

Estimates of infrasonic array gain patterns  

SciTech Connect

Infrasonic array gain patterns are discussed and estimated for the infrasonic frequency range and array geometries under consideration by the Conference on Disarmament in the International Monitoring System (IMS). The larger array spacing being considered for the IMS infrasonic arrays is found to be appropriate in maintaining directivity of the steered beam at lower frequencies. A modestly filled array is found to offer great improvement in narrow band side- lobe suppression at higher frequencies, allowing the benefit of greater directivity of the steered beam at these higher frequencies. Narrow band side-lobe suppression is considered of importance in mitigating frequent, naturally occurring `micro-barom` signals in the southern hemisphere.

Armstrong, W.T.; Whitaker, R.W.

1996-10-01

224

Origin of the highly elevated Pyrenean peneplain  

Microsoft Academic Search

Peneplanation of mountain ranges is generally considered the result of long-term erosional processes that smooth relief and lower elevation near sea level. Therefore peneplain remnants at high elevation in mountain ranges are used to infer posttectonic surface uplift. Such an interpretation has been proposed for the Pyrenees where high-elevation, low-relief erosional surfaces rose up to more than 2000 m. Because

Julien Babault; Jean Van Den Driessche; Stéphane Bonnet; Sébastien Castelltort; Alain Crave

2005-01-01

225

Ding! Going Up? Elevators and Engineering  

NSDL National Science Digital Library

Students create model elevator carriages and calibrate them, similar to the work of design and quality control engineers. Students use measurements from rotary encoders to recreate the task of calibrating elevators for a high-rise building. They translate the rotations from an encoder to correspond to the heights of different floors in a hypothetical multi-story building. Students also determine the accuracy of their model elevators in getting passengers to their correct destinations.

Applying Mechatronics to Promote Science (AMPS) GK-12 Program,

226

Gain control in the sonar of odontocetes.  

PubMed

The sonar of odontocetes processes echo-signals within a wide range of echo levels. The level of echoes varies widely by tens of decibels depending on the level of the emitted sonar pulse, the target strength, the distance to the target, and the sound absorption by the water media. The auditory system of odontocetes must be capable of effective perception, analysis, and discrimination of echo-signals within all this variability. The sonar of odontocetes has several mechanisms to compensate for the echo-level variation (gain control). To date, several mechanisms of the biosonar gain control have been revealed in odontocetes: (1) adjustment of emitted sonar pulse levels (the longer the distance to the target, the higher the level of the emitted pulse), (2) short-term variation of hearing sensitivity based on forward masking of the echo by the preceding self-heard emitted pulse and subsequent release from the masking, and (3) active long-term control of hearing sensitivity. Recent investigations with the use of the auditory evoked-potential technique have demonstrated that these mechanisms effectively minimize the variation of the response to the echo when either the emitted sonar pulse level, or the target distance, or both vary within a wide range. A short review of these data is presented herein. PMID:23132646

Ya Supin, Alexander; Nachtigall, Paul E

2013-06-01

227

Risk Insights Gained from Fire Incidents  

SciTech Connect

There now exist close to 20 years of history in the application of Probabilistic Risk Assessment (PRA) for the analysis of fire risk at nuclear power plants. The current methods are based on various assumptions regarding fire phenomena, the impact of fire on equipment and operator response, and the overall progression of a fire event from initiation through final resolution. Over this same time period, a number of significant fire incidents have occurred at nuclear power plants around the world. Insights gained from US experience have been used in US studies as the statistical basis for establishing fire initiation frequencies both as a function of the plant area and the initiating fire source.To a lesser extent, the fire experience has also been used to assess the general severity and duration of fires. However, aside from these statistical analyses, the incidents have rarely been scrutinized in detail to verify the underlying assumptions of fire PRAs. This paper discusses an effort, under which a set of fire incidents are being reviewed in order to gain insights directly relevant to the methods, data, and assumptions that form the basis for current fire PRAs. The paper focuses on the objectives of the effort, the specific fire events being reviews methodology, and anticipated follow-on activities.

Kazarians, Mardy; Nowlen, Steven P.

1999-06-10

228

Automatic gain control for Raman lidar signals  

NASA Astrophysics Data System (ADS)

Electronic component improvements allow everyone to use them for performing new features in different applications. Lidar signal control is matter of continuous design and it can be studied in order to increase signal-to-noise ratio. Fortunately, the advent, of programmable gain amplifiers, switching capacitor filters and specific AD converters, is the stimulus of improving lidar signal quality. The main scope of this paper is to design and to realize a hardware simulator capable of reproducing the behavior of lidar signal control. This paper aims at describing the results of an automatic control system for Raman lidar signals. The system is based on the following units: laser source, damper, PMT (Photomultiplier), current - to - voltage converter, switched capacitor filter, programmable gain amplifier, A/D converter and FIR filter. This configuration allows the use of FIR filter that is not strictly necessary but it can help in adapting signal according to the amplitude. One of the main advantage of this system is to obtain a flexible and programmable board.

Lay-Ekuakille, Aimé; Vendramin, Giuseppe; Trotta, Amerigo

2008-12-01

229

On a lunar space elevator  

NASA Astrophysics Data System (ADS)

We consider a space elevator system for lunar surface access that consists of a space station in circumlunar orbit, a cable reaching down to some meters above the surface and a magnetically levitated vehicle driven by a linear motor. It accelerates the load to be lifted to the speed of the cable end. Loads to be delivered are either put on the vehicle and slowed down by it or they are slowed down by a sand braking technique in a mare terrain. It is technically possible to operate this transport system nearly without fuel supply from Earth. We calculate various steel cable dimensions for a static stress maximum of 1/5th of the tensile strength. The process of takeover is considered in detail. Five ways of eliminating the adverse large cable elongation due to the load are described. The touchdown process and behaviour of the cable after disconnection are analysed. The positive difference between the speed of the load at takeover and cable end can excite a large inplane swing motion. We propose to damp it by a dissipative pulley that hangs in a loop of wire leading to the ends of two beams mounted on the space station tangentially to the orbit, the pulley's core being connected with the load. Roll librations are damped by energy losses in the elastic beams; damping can be reinforced by viscous beam elements and/or controlled out-of-plane motions of the beams. We argue in favour of the possibility of fast deployment. The problems of vehicle vibrations and agglutination at sand braking blades are underlined and their combined experimental investigation is suggested.

Lemke, E. H.

230

Cholecystokinin Elevates Mouse Plasma Lipids  

PubMed Central

Cholecystokinin (CCK) is a peptide hormone that induces bile release into the intestinal lumen which in turn aids in fat digestion and absorption in the intestine. While excretion of bile acids and cholesterol into the feces eliminates cholesterol from the body, this report examined the effect of CCK on increasing plasma cholesterol and triglycerides in mice. Our data demonstrated that intravenous injection of [Thr28, Nle31]-CCK at a dose of 50 ng/kg significantly increased plasma triglyceride and cholesterol levels by 22 and 31%, respectively, in fasting low-density lipoprotein receptor knockout (LDLR?/?) mice. The same dose of [Thr28, Nle31]-CCK induced 6 and 13% increases in plasma triglyceride and cholesterol, respectively, in wild-type mice. However, these particular before and after CCK treatment values did not achieve statistical significance. Oral feeding of olive oil further elevated plasma triglycerides, but did not alter plasma cholesterol levels in CCK-treated mice. The increased plasma cholesterol in CCK-treated mice was distributed in very-low, low and high density lipoproteins (VLDL, LDL and HDL) with less of an increase in HDL. Correspondingly, the plasma apolipoprotein (apo) B48, B100, apoE and apoAI levels were significantly higher in the CCK-treated mice than in untreated control mice. Ligation of the bile duct, blocking CCK receptors with proglumide or inhibition of Niemann-Pick C1 Like 1 transporter with ezetimibe reduced the hypercholesterolemic effect of [Thr28, Nle31]-CCK in LDLR?/? mice. These findings suggest that CCK-increased plasma cholesterol and triglycerides as a result of the reabsorption of biliary lipids from the intestine.

Zhou, Lichun; Yang, Hong; Lin, Xinghua; Okoro, Emmanuel U.; Guo, Zhongmao

2012-01-01

231

National requirements for improved elevation data  

USGS Publications Warehouse

This report presents the results of surveys, structured interviews, and workshops conducted to identify key national requirements for improved elevation data for the United States and its territories, including coastlines. Organizations also identified and reported the expected economic benefits that would be realized if their requirements for improved elevation were met (appendixes 1–3). This report describes the data collection methodology and summarizes the findings. Participating organizations included 34 Federal agencies, 50 States and two territories, and a sampling of local governments, tribes, and nongovernmental orgnizations. The nongovernmental organizations included The Nature Conservancy and a sampling of private sector businesses. These data were collected in 2010-2011 as part of the National Enhanced Elevation Assessment (NEEA), a study to identify program alternatives for better meeting the Nation’s elevation data needs. NEEA tasks included the collection of national elevation requirements; analysis of the benefits and costs of meeting these requirements; assessment of emerging elevation technologies, lifecycle data management needs, and costs for managing and distributing a national-scale dataset and derived products; and candidate national elevation program alternatives that balance costs and benefits in meeting the Nation’s elevation requirements. The NEEA was sponsored by the National Digital Elevation Program (NDEP), a government coordination body with the U.S. Geological Survey (USGS) as managing partner that includes the National Geospatial-Intelligence Agency (NGA), the Federal Emergency Management Agency (FEMA), the Natural Resources Conservation Service (NRCS), the U.S. Army Corps of Engineers (USACE), and the National Oceanic and Atmospheric Administration (NOAA), among the more than a dozen agencies and organizations. The term enhanced elevation data as used in this report refers broadly to three-dimensional measurements of land or submerged topography, built features, vegetation structure, and other landscape detail. Additional information about NEEA and its later use in the development of a 3D Elevation Program (3DEP) can be found at http://nationalmap.gov/3DEP/index.html.

Snyder, Gregory I.; Sugarbaker, Larry J.; Jason, Allyson L.; Maune, David F.

2014-01-01

232

Changes in wetland sediment elevation following major storms: implications for estimating trends in relative sea-level rise  

USGS Publications Warehouse

Hurricanes can be important agents of geomorphic change in coastal marshes and mangrove forests. Hurricanes can cause large-scale redistribution of sediments within the coastal environment resulting in sedimentation, erosion, disruption of vegetated substrates, or some combination of these processes in coastal wetlands. It has been proposed that such sediment pulsing events are important at maintaining wetland sediment elevations in sediment-poor settings with high rates of relative sea-level rise, such as the Mississippi River Delta. But do these pulsing events result in a net gain in sediment elevation even when substantial amounts of sediment are deposited? Clearly sediment erosion and scour would result in a loss of elevation. But will a substantial sediment deposit on poorly consolidated sediments always result in a net gain in elevation? If the wetland vegetation is killed by wind, tidal surge, or the introduction of saline water, will there be a collapse of sediment elevation in the absence of root production and ongoing decomposition of root matter? During the past decade several wetlands where my colleagues and I have monitored sedimentation and elevation change have been struck by one to several hurricanes. This paper describes the range of sediment elevation responses to hurricane strikes, the suggested mechanisms driving those responses, the implications for estimating long-term trends in relative sea-level rise, and future research needs for improving our understanding of the role that major storms play in wetland sediment elevation dynamics. For many wetlands the change in sediment elevation was directly proportional to the amount of sediment deposited by the storm. But surprisingly, there was a loss of elevation in some wetlands with substantial sediment deposits. In these wetlands, the impact of the storm was either direct (sedimentation and compaction) or indirect (vegetation death), and the effect on sediment elevation was either permanent or temporary. For example, 2 cm of sediment deposited by Hurricane Andrew on a healthy salt marsh in south Louisiana had a direct and positive effect on sediment elevation. But in a deteriorated salt marsh a 3 cm thick sediment deposit was associated with a permanent loss in elevation (we have monitored this site for 10 years). The apparent mechanism driving elevation loss was compaction of the weakened substrate by the weight of the sediment deposit, the storm surge waters, or both. Clearly, storm-related sediment pulses are not going to save this marsh from becoming submerged by rising sea level. A temporary loss in elevation, as much as 2 cm, was observed in a North Carolina salt marsh with a highly organic substrate after each of 3 successive hurricanes even when sediment was deposited. The loss in elevation was apparently related to degassing of the chronically flooded substrate while the rebound in elevation was apparently related to a temporary drawdown of marsh water levels. Interestingly, sediment elevation increased after Hurricane Dennis in 1999, although the increase was less than the thickness of the sediment deposit. Further research is required to determine the mechanisms driving storm-related elevation change (i.e., compaction and expansion) in this marsh. There were two marshes where the gain in sediment elevation was greater than the thickness of the sediment deposit, but the effect was short-lived. In a high salt marsh in southern California, we hypothesize that the temporary spike in elevation was related to the flushing of salts from the hypersaline soils, which enhanced root growth that led to an increase in elevation. In a marsh with a highly organic substrate in north Florida, temporary increases in elevation (as much as 2 cm) greater than the thickness of the sediment deposit were apparently related to groundwater fluxes, which may have been influenced by enhanced runoff from storm rainfall. Lastly, Hurricane Mitch

Cahoon, D.R.

2003-01-01

233

Robust Gain-Scheduled Fault Tolerant Control for a Transport Aircraft  

NASA Technical Reports Server (NTRS)

This paper presents an application of robust gain-scheduled control concepts using a linear parameter-varying (LPV) control synthesis method to design fault tolerant controllers for a civil transport aircraft. To apply the robust LPV control synthesis method, the nonlinear dynamics must be represented by an LPV model, which is developed using the function substitution method over the entire flight envelope. The developed LPV model associated with the aerodynamic coefficient uncertainties represents nonlinear dynamics including those outside the equilibrium manifold. Passive and active fault tolerant controllers (FTC) are designed for the longitudinal dynamics of the Boeing 747-100/200 aircraft in the presence of elevator failure. Both FTC laws are evaluated in the full nonlinear aircraft simulation in the presence of the elevator fault and the results are compared to show pros and cons of each control law.

Shin, Jong-Yeob; Gregory, Irene

2007-01-01

234

Unconventional modes in lasers with spatially varying gain and loss  

SciTech Connect

We discuss a class of lasing modes created by a spatially inhomogeneous gain profile. These lasing modes are ''extra modes,'' in addition to, and very different from, conventional lasing modes, which arise from the passive cavity resonances. These new modes do not have high intensity across the entire gain region, but instead are localized at the gain boundary and throughout the gain-free region. They are surface modes, originating from the transmission resonances of the gain-free region. Using an S-matrix description we connect these surface modes to the lasing modes in PT-symmetric (balanced gain-loss) cavities.

Ge Li; Tuereci, H. E. [Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544 (United States); Chong, Y. D.; Stone, A. D. [Department of Applied Physics, Yale University, New Haven, Connecticut 06520 (United States); Rotter, S. [Institute for Theoretical Physics, Vienna University of Technology, A-1040 Vienna (Austria)

2011-08-15

235

Rapid Postnatal Weight Gain and Visceral Adiposity in Adulthood: The Fels Longitudinal Study  

PubMed Central

Rapid infant weight gain is associated with increased abdominal adiposity, but there is no published report of the relationship of early infant growth to differences in specific adipose tissue depots in the abdomen, including visceral adipose tissue (VAT). In this study, we tested the associations of birth weight, infant weight gain, and other early life traits with VAT, abdominal subcutaneous adipose tissue (ASAT), and other body composition measures using magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry in middle adulthood (mean age = 46.5 years). The sample included 233 appropriate for gestational age singleton white children (114 males) enrolled in the Fels Longitudinal Study. Multivariate-adjusted general linear models were used to test the association of infant weight gain (from 0 to 2 years), maternal BMI, gestational age, parity, maternal age, and other covariates with adulthood body composition. Compared to infants with slow weight gain, rapid weight gain was associated with elevated risk of obesity (adjusted odds ratio = 4.1, 95% confidence interval = 1.4, 11.1), higher total body fat (+7 kg, P = 0.0002), percent body fat (+5%, P = 0.0006), logVAT mass (+0.43 kg, P = 0.02), logASAT mass (+0.47 kg, P = 0.001), and percent abdominal fat (+5%, P = 0.03). There was no evidence that the increased abdominal adipose tissue was due to a preferential deposition of VAT. In conclusion, rapid infant weight gain is associated with increases in both VAT and ASAT, as well as total adiposity and the risk of obesity in middle adulthood.

Demerath, Ellen W.; Reed, Derek; Choh, Audrey C.; Soloway, Laura; Lee, Miryoung; Czerwinski, Stefan A.; Chumlea, William C.; Siervogel, Rogers M.; Towne, Bradford

2009-01-01

236

DESIGN AND DEPLOYMENT OF A SPACE ELEVATOR  

Microsoft Academic Search

The space elevator was first proposed in the 1960s as a method of getting into space. The initial studies of a space elevator outlined the basic concept of a cable strung between Earth and space but concluded that no material available at the time had the required properties to feasibly construct such a cable. With the discovery of carbon nanotubes

Bradley C. Edwards

2000-01-01

237

Space Elevator Ribbon Mass and Taper Ratio  

Microsoft Academic Search

Assumptions about tensile strength and density aect the space elevator ribbon taper ratio, and therefore its mass. We examine the technical trade-os between material properties and total mass of a modern space elevator ribbon, and the economic trade-os between ribbon mass, the number of rocket launches required to loft the initial ribbon, and the time required to build the ribbon

Tom Nugent

238

Satellite Placement Using a Partial Space Elevator  

Microsoft Academic Search

The space elevator has been proposed as an alternate method for launching cargo into space. However, the construction of such a structure requires a material much stronger than any currently in existence. Instead, a partial elevator is considered for satellite placement. In the first part of the thesis, the fundamentals of very long tethered systems are studied. From static analysis

Pamela Woo

2009-01-01

239

A Space Elevator Based Exploration Strategy  

NASA Astrophysics Data System (ADS)

Technological advances and recent studies have laid the groundwork for eventual construction of a space elevator. Within 15 years an operational space elevator could be running from Earth to beyond geosynchronous. The basic mechanical operation allows for low operational cost ($250/kg), high capacity (>13tons, >5tons/day/elevator), a range of destinations (LEO, GEO, Moon, Mars, Asteroids, and Venus), and minimal launch forces. The low risk operation of the space elevator would allow large scale robotic and human exploration of the solar system. An operational elevator will immediately move primary interest from LEO to GEO for many activities and open commercial space activities such as solar power satellite arrays for beaming power to Earth. Robotic exploration to all destinations would be able to use larger, fixed structures, more massive platforms and be launched for a fraction of current costs. Human exploration could start at GEO for maintaining commercial assets, and enhanced Earth-observing systems and then step to Mars where a receiving elevator could also be established. This paper will cover the basics of a space elevator and a comprehensive strategy for human and exploratory use of space based on the space elevator.

Edwards, Bradley C.

2004-02-01

240

Energy gain induced by boundary crisis  

NASA Astrophysics Data System (ADS)

We consider a nonlinear system and show the unexpected and surprising result that, even for high dissipation, the mean energy of a particle can attain higher values than when there is no dissipation in the system. We reconsider the time-dependent annular billiard in the presence of inelastic collisions with the boundaries. For some magnitudes of dissipation, we observe the phenomenon of boundary crisis, which drives the particles to an asymptotic attractive fixed point located at a value of energy that is higher than the mean energy of the nondissipative case and so much higher than the mean energy just before the crisis. We should emphasize that the unexpected results presented here reveal the importance of a nonlinear dynamics analysis to explain the paradoxical strategy of introducing dissipation in the system in order to gain energy.

Abud, C. Vieira; de Carvalho, R. Egydio

2011-09-01

241

High gain selective metal organic framework preconcentrators  

US Patent & Trademark Office Database

Novel metal organic framework (MOF) molecules and methods of synthesizing them are described. MOFs are organometallic crystalline structures that have high sorption capacity due to high surface area, tailorable selectivity, an inert nature, and thermal stability at high temperatures. MOFs may be used as sorbents in preconcentrators for analytical devices to provide orders of magnitude of improved sensitivity in analyte detection. MOFs are also useful as sorbents in new compact and portable micropreconcentrator designs such as a modified purge and trap system and a multi-valve microelectromechanical system (MEMS) to achieve high gain in analyte detection. Further, MOFs may be used as coatings for novel microstructure arrays in micropreconcentrators where the microstructures are designed to increase the surface area to volume ratio inside the micropreconcentrator while minimizing the pressure drop across the micropreconcentrator.

2012-02-28

242

The gamma efficiency of the GAINS spectrometer  

NASA Astrophysics Data System (ADS)

The GAINS (Germanium Array for Inelastic Neutron Scattering) setup was recently installed at the GELINA (Geel Linear Accelerator) neutron source of EC-JRC-IRMM. In order to produce reliable neutron inelastic cross-section data the setup requires a precise efficiency calibration for each sample under investigation. These samples represent extended sources in non-standard orientations and with significant self-attenuation of gamma rays. We present in detail the efficiency calibration procedure performed with two Monte Carlo simulations using MCNP and GEANT4. A good agreement is found between the two independent approaches. The general features of the simulations are discussed together with an in-depth description of the various factors influencing the efficiency.

Deleanu, D.; Borcea, C.; Dessagne, Ph.; Kerveno, M.; Negret, A.; Plompen, A. J. M.; Thiry, J. C.

2010-12-01

243

North Elevation: LowLift Pumping Station (East) 2008; West Elevation and ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

North Elevation: Low-Lift Pumping Station (East) 2008; West Elevation and Floor Plan: Outbuilding - Robert B. Morse Water Filtration Plant, 10700 and 10701 Columbia Pike, Silver Spring, Montgomery County, MD

244

83. Credit PG&E. Front (east) elevation and south (tailrace) elevation. ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

83. Credit PG&E. Front (east) elevation and south (tailrace) elevation. Note cornice on facade and new roof. Photo taken 10 November 1927. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

245

Antipsychotic-induced insulin resistance and postprandial hormonal dysregulation independent of weight gain or psychiatric disease.  

PubMed

Atypical antipsychotic (AAP) medications that have revolutionized the treatment of mental illness have become stigmatized by metabolic side effects, including obesity and diabetes. It remains controversial whether the defects are treatment induced or disease related. Although the mechanisms underlying these metabolic defects are not understood, it is assumed that the initiating pathophysiology is weight gain, secondary to centrally mediated increases in appetite. To determine if the AAPs have detrimental metabolic effects independent of weight gain or psychiatric disease, we administered olanzapine, aripiprazole, or placebo for 9 days to healthy subjects (n = 10, each group) under controlled in-patient conditions while maintaining activity levels. Prior to and after the interventions, we conducted a meal challenge and a euglycemic-hyperinsulinemic clamp to evaluate insulin sensitivity and glucose disposal. We found that olanzapine, an AAP highly associated with weight gain, causes significant elevations in postprandial insulin, glucagon-like peptide 1 (GLP-1), and glucagon coincident with insulin resistance compared with placebo. Aripiprazole, an AAP considered metabolically sparing, induces insulin resistance but has no effect on postprandial hormones. Importantly, the metabolic changes occur in the absence of weight gain, increases in food intake and hunger, or psychiatric disease, suggesting that AAPs exert direct effects on tissues independent of mechanisms regulating eating behavior. PMID:23835329

Teff, Karen L; Rickels, Michael R; Grudziak, Joanna; Fuller, Carissa; Nguyen, Huong-Lan; Rickels, Karl

2013-09-01

246

Biological Determinants Linking Infant Weight Gain and Child Obesity: Current Knowledge and Future Directions12  

PubMed Central

Childhood obesity rates have reached epidemic proportions. Excessive weight gain in infancy is associated with persistence of elevated weight status and later obesity. In this review, we make the case that weight gain in the first 6 mo is especially predictive of later obesity risk due to the metabolic programming that can occur early postpartum. The current state of knowledge regarding the biological determinants of excess infant weight gain is reviewed, with particular focus on infant feeding choice. Potential mechanisms by which different feeding approaches may program the metabolic profile of the infant, causing the link between early weight gain and later obesity are proposed. These mechanisms are likely highly complex and involve synergistic interactions between endocrine effects and factors that alter the inflammatory and oxidative stress status of the infant. Gaps in current knowledge are highlighted. These include a lack of data describing 1) what type of infant body fat distribution may impart risk and 2) how maternal metabolic dysfunction (obesity and/or diabetes) may affect milk composition and exert downstream effects on infant metabolism. Improved understanding and management of these early postnatal determinants of childhood obesity may have great impact on reducing its prevalence.

Young, Bridget E.; Johnson, Susan L.; Krebs, Nancy F.

2012-01-01

247

Path loss and antenna gain considerations for unattended ground sensor (UGS) systems  

NASA Astrophysics Data System (ADS)

Unatttended Ground Sensor (UGS) systems are adversely affected by the physics of RF propagation at low elevations. Units are often located at or below ground level in an effort to reduce the visual signature. Two key elements of the link budget work are compromised by the ground level antenna height: path loss and antenna gain. A two-ray reflected path model predicts that path loss increases by R4 with distance separating units and is inversely related to the height of the antennas. Strict adherence to this model indicates that infinite path loss is incurred by antennas located at the ground (height = 0). Ground wave propagation allows for a minimum effective antenna height to be assigned thereby eliminating this theoretical anomaly. Regardless, ground reflections for low elevation RF propagation result in up to 40 dB or more of extra path losses when compared to the free space model. Antenna modeling programs used to predict antenna patterns also paint a grim picture for UGS units. Monopole antennas have a null at the horizon and can be predicted to have antenna gains less than -20 dBi at low takeoff angles. Combining path loss and antenna gain to obtain an overall picture of the decrease in signal level is not straightforward. Simply combining the two sources of signal loss results in predicted performance that is much less than what is measured with real hardware. This paper examines the interaction of path loss and antenna gain and presents a reasonable approach for accounting for both in the link budget. Experimental results are presented to support the models.

Bruns, Thomas

2004-09-01

248

DEVELOPMENT & ASSESSMENT OF THE GLOBAL LAND ONE-KM BASE ELEVATION DIGITAL ELEVATION MODEL (GLOBE)  

Microsoft Academic Search

The Global Land One-kilometer Base Elevation (GLOBE) digital elevation model is the most thoroughly designed, reviewed, and documented global digital elevation dataset to date. GLOBE was developed by an international group of specialists, cooperating with the Committee on Earth Observation Satellites (CEOS) Working Group on Information Systems and Services (WGISS), International Geosphere-Biosphere Programme's Data and Information System (IGBP- DIS), and

David A. Hastings; P. K. Dunbar

249

Dual AMP features variable gain and high bandwidth  

NASA Astrophysics Data System (ADS)

Variable-gain amplifiers (VGAs) are important components in many receiver systems. One such VGA design intended for lightwave transmission systems operating at gigabit-per-second rates provides 2.5-GHz bandwidth and 40-dB gain.

Pfund, George; Zhang, Jim; Wu, Jieh-Tsorng

1992-02-01

250

Giant modal gain in a metal-semiconductor waveguide  

Microsoft Academic Search

We show that a giant modal gain is achievable near surface plasmon resonance for guided modes in a metal-semiconductor-metal plasmonic waveguide. The giant gain is shown to originate from a reduction of average energy velocity.

D. Li; C. Z. Ning

2009-01-01

251

TV in Child's Bedroom Tied to Weight Gain  

MedlinePLUS

... Child's Bedroom Tied to Weight Gain But 'active' video games might help youngsters stay slim, researchers stay (*this ... to gain weight. But kids who play active video games might lose unwanted pounds, according to two new ...

252

Some Measurements of Height Gain at V.H.F.  

National Technical Information Service (NTIS)

Some of the published work on antenna height gain is reviewed and limitations of the currently available information are highlighted. Comparison is then made with the results of height gain experiments undertaken in southeastern England at frequencies of ...

J. Fairbrother K. A. Hughes D. M. Holden

1987-01-01

253

Time-varying high-gain observers for numerical differentiation  

Microsoft Academic Search

In this paper, we propose high-gain numerical differentiators for estimating the higher derivatives of a given signal. We consider time varying high-gain vectors converging exponentially to the high-gain vectors introduced by F. Esfandiari and K.H. Khalil (1992) in an earlier paper. The dynamics of these time-varying high-gain vectors can be chosen in order to achieve specific objectives, such as peaking

Yacine Chitour

2002-01-01

254

Gain for neutron polycapillary lens as a function of wavelength  

NASA Astrophysics Data System (ADS)

A focusing lens using glass polycapillary fibers has achieved a current density gain of 80 for a polychromatic beam from a cold-neutron guide. The intensity gain of a lens depends on both the wavelength and the divergence of the incoming beam, and a simulation is required to determine the trends in the gain as a function of wavelength. However, measurement has shown that the gain is relatively insensitive to wavelength.

Mildner, D. F. R.; Chen, H.; Sharov, V. A.; Downing, R. G.; Xiao, Q. F.

1995-02-01

255

External rotation during elevation of the arm  

PubMed Central

Background Knowledge about the pattern of rotation during arm elevation is necessary for a full understanding of shoulder function, and it is also useful for planning of rehabilitation protocols to restore range of motion in shoulders in disorder. However, there are insufficient in vivo data available. Methods We investigated dynamic arm rotation during elevation in different planes using 30 shoulders in 15 healthy men (age range 21–33 years). Both arms were moved from neutral dependent position to maximum elevated position in 4 planes from laterally to anteriorly, and each dynamic course of motion was traced using a 3-dimensional motion capture system. Results Patterns of rotation were categorized as being one of 2 types, depending on whether or not external rotation peaked before the arm reached the maximum elevated position. External rotation peaked at 122? (SD14) of abduction, then decreased according to the arm movement in the lateral planes, but increased gradually to maximum elevated position in the anterior planes. Mean maximal angles of external rotation (in degrees) during elevation were 27 (SD11), 13 (SD13), 3 (SD9), and 3 (SD5), from laterally to anteriorly. Interpretation There were differences in rotational patterns, and more external rotation was needed to reach maximum elevation in lateral planes than in anterior planes.

Hashimoto, Takashi; Nobuhara, Katsuya

2009-01-01

256

26 CFR 1.737-1 - Recognition of precontribution gain.  

Code of Federal Regulations, 2013 CFR

...Property A2 is long-term, U.S.-source capital gain or loss. The character of...Property A3 is long-term, foreign-source capital gain. B contributes Property...of the net positive amounts. U.S.-source and foreign-source gains must be...

2013-04-01

257

Gain for neutron polycapillary lens as a function of wavelength  

Microsoft Academic Search

A focusing lens using glass polycapillary fibers has achieved a current density gain of 80 for a polychromatic beam from a cold-neutron guide. The intensity gain of a lens depends on both the wavelength and the divergence of the incoming beam, and a simulation is required to determine the trends in the gain as a function of wavelength. However, measurement

D. F. R. Mildner; H. Chen; V. A. Sharov; R. G. Downing; Q. F. Xiao

1995-01-01

258

Design gain characteristic of dual-pump fiber Raman amplifier  

NASA Astrophysics Data System (ADS)

To design gain characteristic of dual-pump fiber Raman amplifier, an effect optimal model is investigated under different conditions, such as maximal gain and minimal gain ripper. Impact of pumps interaction, pump wavelength selection, signals interaction and signal saturation are discussed.

Chen, Jian; Zhang, Wei; Liu, Xiaoming; Peng, Jiangde; Zhou, BingKun

2001-10-01

259

Measurements and modeling of gain coefficients for neodymium laser glasses  

Microsoft Academic Search

Small-signal gain coefficients are reported for neodymium in silicate, phosphate, fluorophosphate, and fluoroberyllate laser glasses. Measurements were made in a disk amplifier under identical conditions. Using spectroscopic data as the input, amplifier gain is calculated as a function of flashlamp energy, pumping pulse duration, disk thickness, and Nd-doping. The agreement between predicted and measured gains is generally with ±10 percent,

GARY J. LINFORD; R. ALLYN SAROYAN; JOHN B. TRENHOLME; MARVIN J. WEBER

1979-01-01

260

Modeling of gain in erbium-doped fiber amplifiers  

Microsoft Academic Search

An analytic method is described for fully characterizing the gain of an erbium-doped fiber amplifier (EDFA) that is based on easily measured monochromatic absorption data. The analytic expressions presented, which involve the solution of one transcendental equation, can predict signal gains and pump absorptions in an amplifier containing an arbitrary number of pumps and signals from arbitrary directions. The gain

A. A. M. Saleh; R. M. Jopson; J. D. Evankow; J. Aspell

1990-01-01

261

Gain-dependent polarization properties of vertical-cavity lasers  

Microsoft Academic Search

We show that the partitioning of power into the two orthogonal eigen polarizations of infra-red gain-guided vertical cavity lasers depends upon the relative spectral overlap of the nondegenerate polarization cavity resonances with the laser gain spectrum. Furthermore, at the condition where the polarization resonances and the peak laser gain are aligned, abrupt switching of power between the eigen polarizations is

Kent D. Choquette; Richard P. Schneider; K. L. Lear; Ronald E. Leibenguth

1995-01-01

262

Compensation-Based Optimization Methodology for Gain-Boosted OPAMP.  

National Technical Information Service (NTIS)

A gain-boosted OPAMP design methodology is presented. The methodology provides a systematic way of gain-boosted OPAMP optimization in terms of AC response and settling performance. The evolution of the major poles and zeros of the gain-boosted OPAMP is st...

J. Yuan N. Farhat

2001-01-01

263

Studies on pressure-gain combustion engines  

NASA Astrophysics Data System (ADS)

Various aspects of the pressure-gain combustion engine are investigated analytically and experimentally in the current study. A lumped parameter model is developed to characterize the operation of a valveless pulse detonation engine. The model identified the function of flame quenching process through gas dynamic process. By adjusting fuel manifold pressure and geometries, the duration of the air buffer can be effectively varied. The parametric study with the lumped parameter model has shown that engine frequency of up to approximately 15 Hz is attainable. However, requirements for upstream air pressure increases significantly with higher engine frequency. The higher pressure requirement indicates pressure loss in the system and lower overall engine performance. The loss of performance due to the pressure loss is a critical issue for the integrated pressure-gain combustors. Two types of transitional methods are examined using entropy-based models. An accumulator based transition has obvious loss due to sudden area expansion, but it can be minimized by utilizing the gas dynamics in the combustion tube. An ejector type transition has potential to achieve performance beyond the limit specified by a single flow path Humphrey cycle. The performance of an ejector was discussed in terms of apparent entropy and mixed flow entropy. Through an ideal ejector, the apparent part of entropy increases due to the reduction in flow unsteadiness, but entropy of the mixed flow remains constant. The method is applied to a CFD simulation with a simple manifold for qualitative evaluation. The operation of the wave rotor constant volume combustion rig is experimentally examined. The rig has shown versatility of operation for wide range of conditions. Large pressure rise in the rotor channel and in a section of the exhaust duct are observed even with relatively large leakage gaps on the rotor. The simplified analysis indicated that inconsistent combustion is likely due to insufficient fuel near the ignition source. However, it is difficult to conclude its fuel distribution with the current setup. Additional measurement near the rotor interfaces and better fuel control are required for the future test.

Matsutomi, Yu

264

US GeoData digital elevation models  

USGS Publications Warehouse

Digital elevation model (DEM) data consist of a sampled array of regularly spaced elevation values referenced horizontally either to a Universal Transverse Mercator (UTM) projection or to a geographic coordinate system. The grid cells are spaced at regular intervals along south to north profiles that are ordered from west to east. the U.S> Geological Survey (USGS) produces five primary types of elevation data: 7.5-minute DEM, 30-minute DEM, 1-degree DEM, 7.5-minute Alaska DEM, and 15-minute Alaska DEM.

Geological Survey (U.S.)

1997-01-01

265

US GeoData Digital Elevation Models  

USGS Publications Warehouse

Digital elevation model (DEM) data are arrays of regularly spaced elevation values referenced horizontally either to a Universal Transverse Mercator (UTM) projection or to a geographic coordinate system. The grid cells are spaced at regular intervals along south to north profiles that are ordered from west to east. The U.S. Geological Survey (USGS) produces five primary types of elevation data: 7.5-minute DEM, 30-minute DEM, 1-degree DEM, 7.5-minute Alaska DEM, and 15-minute Alaska DEM.

Geological Survey (U.S.)

2000-01-01

266

Electric top drives gain wide industry acceptance  

SciTech Connect

Since its introduction, the top drive drilling system has gained acceptance as a productive and safe method for drilling oil and gas wells. Originally, the system was used mostly for offshore and higher cost land drilling, and it had to be installed as a permanent installation because of its enormous weight and size. Essentially, a top drive replaces the kelly and rotary table as the means of rotating drillpipe on oil, gas and geothermal rigs and is considered to be 15% to 40% more efficient than a kelly drive. Top drive systems allow the operator to drill and maintain directional orientation for triple stands and provide tripping efficiency because of the ability to ream and circulate with triple stands, to reduce the risk of stuck pipe or lost wells, and to improve well control and pipe handling safety. The paper describes electric top drives with DC motors, top drives with AC motors, top drives with permanent magnet motors, and top drives with permanent magnet brushless synchronous motors.

Riahi, M.L.

1998-05-01

267

GD SDR Automatic Gain Control Characterization Testing  

NASA Technical Reports Server (NTRS)

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showi ng how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

268

GD SDR Automatic Gain Control Characterization Testing  

NASA Technical Reports Server (NTRS)

The General Dynamics (GD) S-Band software defined radio (SDR) in the Space Communications and Navigation (SCAN) Testbed on the International Space Station (ISS) will provide experimenters an opportunity to develop and demonstrate experimental waveforms in space. The GD SDR platform and initial waveform were characterized on the ground before launch and the data will be compared to the data that will be collected during on-orbit operations. A desired function of the SDR is to estimate the received signal to noise ratio (SNR), which would enable experimenters to better determine on-orbit link conditions. The GD SDR does not have an SNR estimator, but it does have an analog and a digital automatic gain control (AGC). The AGCs can be used to estimate the SDR input power which can be converted into a SNR. Tests were conducted to characterize the AGC response to changes in SDR input power and temperature. This purpose of this paper is to describe the tests that were conducted, discuss the results showing how the AGCs relate to the SDR input power, and provide recommendations for AGC testing and characterization.

Nappier, Jennifer M.; Briones, Janette C.

2013-01-01

269

Ignition and high gain with ultrapowerful lasers  

SciTech Connect

Ultrahigh intensity lasers can potentially be used in conjunction with conventional fusion lasers to ignite inertial confinement fusion (ICF) capsules with a total energy of a few tens of kilojoules of laser light, and can possibly lead to high gain with as little as 100 kJ. A scheme is proposed with three phases. First, a capsule is imploded as in the conventional approach to inertial fusion to assemble a high-density fuel configuration. Second, a hole is bored through the capsule corona composed of ablated material, as the critical density is pushed close to the high-density core of the capsule by the ponderomotive force associated with high-intensity laser light. Finally, the fuel is ignited by suprathermal electrons, produced in the high-intensity laser--plasma interactions, which then propagate from critical density to this high-density core. This new scheme also drastically reduces the difficulty of the implosion, and thereby allows lower quality fabrication and less stringent beam quality and symmetry requirements from the implosion driver. The difficulty of the fusion scheme is transferred to the technological difficulty of producing the ultrahigh-intensity laser and of transporting this energy to the fuel.

Tabak, M.; Hammer, J.; Glinsky, M.E.; Kruer, W.L.; Wilks, S.C.; Woodworth, J.; Campbell, E.M.; Perry, M.D. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)); Mason, R.J. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

1994-05-01

270

Enhancement of stimulated Raman scattering of weak-gain Raman modes in a pendant drop by dye-lasing gain  

Microsoft Academic Search

The enhancement of stimulated Raman scattering (SRS) of weak-gain Raman modes in pendant drops is accomplished by overlapping Stokes wavelengths of the Raman modes with the Rhodamine 640 dye-lasing gain region (called the gain-overlap method). The dye concentration and the pumping intensity of frequency-doubled Nd:YAG lasers determine the efficiency of the enhancement. We apply the gain-overlap technique at optimal dye

Xiao-Yun Pu; Zheng Yang; Wing-Kee Lee

2004-01-01

271

Elevated blood pressure in offspring of rats exposed to diverse chemicals during pregnancy.  

PubMed

Adverse intrauterine environments have been associated with increased risk of later cardiovascular disease and hypertension. In an animal model using diverse developmental toxicants, we measured blood pressure (BP), renal nephron endowment, renal glucocorticoid receptor (GR) gene expression, and serum aldosterone in offspring of pregnant Sprague Dawley rats exposed to dexamethasone (Dex), perfluorooctane sulfonate (PFOS), atrazine, perfluorononanoic acid (PFNA), arsenic, or nicotine. BP was assessed by tail cuff photoplethysmography, nephron endowment by confocal microscopy, and renal GR mRNA by qPCR. BP was also measured by telemetry, and corticosterone (CORT) was measured in resting or restrained Dex and atrazine offspring. Treated dams gained less weight during treatment in all groups except arsenic. There were chemical- and sex-specific effects on birth weight, but offspring body weights were similar by weaning. BP was higher in Dex, PFOS, atrazine, and PFNA male offspring by 7-10 weeks. Female offspring exhibited elevated BP at 10 weeks for PFNA and arsenic, and at 37 weeks for Dex, PFOS, and atrazine. Dex, PFOS, and atrazine offspring still exhibited elevated BP at 52-65 weeks of age; others did not. Elevated BP was associated with lower nephron counts. Dex, PFOS, and atrazine offspring had elevated renal GR gene expression. Elevations in BP were also observed in Dex and atrazine offspring by radiotelemetry. Atrazine offspring exhibited enhanced CORT response to restraint. Elevated offspring BP was induced by maternal exposure to toxicants. Because all treatments affected maternal gestational weight gain, maternal stress may be a common underlying factor in these observations. PMID:24218149

Rogers, John M; Ellis-Hutchings, Robert G; Grey, Brian E; Zucker, Robert M; Norwood, Joel; Grace, Curtis E; Gordon, Christopher J; Lau, Christopher

2014-02-01

272

GAIN in the Community Colleges: A Report on the 1992-93 Survey on GAIN Participants and Funding.  

ERIC Educational Resources Information Center

California's Greater Avenues for Independence (GAIN) program is designed to provide education, job training, and support services to help welfare recipients enter the workforce. As part of an effort to monitor the California Community Colleges' (CCC's) GAIN effort, the Office of the Chancellor conducted a study of GAIN student characteristics,…

Eissa, Debbie

273

Gain-phase grating based on spatial modulation of active Raman gain in cold atoms  

SciTech Connect

In order to obtain an atomic grating which can diffract light into the high-order directions more efficiently, a gain-phase grating (GPG) based on the spatial modulation of active Raman gain is theoretically presented. This grating is induced by a pump field and a standing wave in ultracold atoms, and it not only diffracts a weak probe field propagating along a direction normal to the standing wave into the high-order directions, but also amplifies the amplitude of the zero-order diffraction. In contrast with electromagnetically induced grating or electromagnetically induced phase grating, the GPG has larger diffraction efficiencies in the high-order directions. Hence it is more suitable to be utilized as an all-optical router in optical networking and communication.

Kuang Shangqi; Jin Chunshui; Li Chun [Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2011-09-15

274

Polarization-dependent gain and gain saturation in strained semiconductor lasers  

NASA Astrophysics Data System (ADS)

Various power-versus-current characteristics of TE and TM emission from 1.3-pm InGaAsP/InP semiconductor lasers are observed. They are categorized into the single-plarization lasers, the two-polarization coexisting lasers, and the two-polarization switching lasers. A polarization-related rate-equation model with self-saturation and crosssaturation terms are proposed to simulate these measurements. Emission of only one polarization is explained by large difference of gain and loss between the two polarization modes. Coexisting or switching of both polarizations is determined by the self-saturation and cross-saturation of the gain of the two polarization. The rate equation model is justified by the strain-dependent susceptibility. Several possible sources of strain are the slight lattice-mismatch, the superficial silicon-dioxide, and the die bonding and handling.

Yu, Ben-mou; Liu, Jia-ming; LaCourse, Joanne S.

1990-05-01

275

[The variability of functional gain and insertion gain in hearing aid fitting].  

PubMed

Functional gain (FG) and insertion gain (IG) are currently used as real ear gain measurement of hearing aids. The gain differences observed with hearing aid modifications made in order to achieve the desired prescriptive target must be greater than the variability associated with repetition of measurement in order to be really useful. Limited research is available on FG and IG intratester variability. In order to evaluate single variability factors, some studies use experimental designs not common in clinical work-up while others use equipment mot available commercially. The present study evaluates intratester variability of FG and IG (Madsen IGO 1500 equipment) in a typical clinical configuration in 42 users of behind-ear hearing aids. Mean standard deviation of FG test-retest differences was 5.19 dB. Range of variability was expressed in term of centiles. 5-- and 95-- centiles were -9.8 and 8.7 dB respectively. Mean s.d. of IG test-retest differences was 3.18 dB; 5-- and 95-- centiles were -5.2 and 6.05 dB respectively. Major variability was found at higher frequencies. High variability at lower frequencies was also found probably due to sealing problems of ear molds in the ear canal. Accord between FG and IG was also examined. A good mean correspondence in mid frequency range was found (FG-IG mean difference less than 5 dB) with large inter-subject differences between the two measurements (s.d. 11 dB). PMID:1414323

Cuda, D; De Benedetto, M; Leante, M

1992-01-01

276

Gain enhancement in a two-frequency high-gain waveguide free-electron laser  

Microsoft Academic Search

In a waveguide monomode free-electron laser (FEL), two resonant frequencies can be amplified by the electron beam. At the CEA\\/CESTA facility, single-pass high-gain FEL experiments have been performed over the last five years using relativistic electron beams provided by induction linacs. Most of the work was done in the amplifier regime (at the higher frequency) with the aim of producing

T. Lefevre; J. Gardelle; J. L. Rullier; P. Gouard; J. T. Donohue

2002-01-01

277

Moral elevation reduces prejudice against gay men.  

PubMed

Disgust is linked to social evaluation. People with higher disgust sensitivity exhibit more sexual prejudice, and inducing disgust increases sexual prejudice. We tested whether inducing moral elevation, the theoretical opposite of disgust, would reduce sexual prejudice. In four studies (N = 3622), we induced elevation with inspiring videos and then measured sexual prejudice with implicit and explicit measures. Compared to control videos that elicited no particular affective state, we found that elevation reduced implicit and explicit sexual prejudice, albeit very slightly. No effect was observed when the target of social evaluation was changed to race (Black-White). Inducing amusement, another positive emotion, did not significantly affect sexual prejudice. We conclude that elevation weakly but reliably reduces prejudice towards gay men. PMID:24320065

Lai, Calvin K; Haidt, Jonathan; Nosek, Brian A

2014-08-01

278

Atmospheric deposition to high-elevation forests  

SciTech Connect

Three important phenomena characterize atmospheric deposition to high-elevation forests: (1) multiple deposition mechanisms (wet, dry, and cloud deposition), (2) high rates of deposition, and (3) high spatial variability. The high rates of deposition are caused by changes in meteorological conditions with elevation, especially increasing wind speed and cloud immersion frequency. The high spatial variability of deposition is a result of the regulation of cloud and dry deposition rates by microclimatic and canopy structure conditions, which can be extremely heterogeneous in mountain landscapes. Spruce-fir forests are often [open quotes]hot spots[close quotes] of deposition when viewed in a landscape or regional context because of their elevation, exposure, and evergreen canopy. In this talk we will consider atmospheric depositions to high-elevation forests in both the northeastern and southeastern U.S., using field data and geographic information systems to illustrate deposition patterns.

Lovett, G.M.; Weathers, K.C.; Lindberg, S.E. (Institute of Ecosystem Studies, Millbrook, NY (United States) Oak Ridge National Lab., TN (United States))

1994-06-01

279

78 FR 10066 - Final Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...Base (1% annual-chance) Flood Elevations (BFEs) and modified BFEs are made final...encouraged to review the proof Flood Insurance Study and FIRM available at the address...67 Administrative practice and procedure, Flood insurance, Reporting...

2013-02-13

280

76 FR 16722 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...70944. The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Deener Creek, Gum Creek Flooding Effects, Little Red River, Overflow...

2011-03-25

281

78 FR 22221 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Pea Branch and Reedy Branch...Incorporated Areas'' did not address the flooding sources Pea Branch and Reedy...

2013-04-15

282

77 FR 15664 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Kentucky. Specifically, it addresses the flooding sources Little River (backwater effects...of Cadiz, Kentucky'' addressed the flooding sources Little River (backwater...

2012-03-16

283

76 FR 13571 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Areas. Specifically, it addresses the flooding source Shoal Creek. DATES: Comments...Incorporated Areas'' addressed the flooding source Shoal Creek. That table...

2011-03-14

284

76 FR 13570 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Areas. Specifically, it addresses the flooding source South Creek. DATES: Comments...Incorporated Areas'' addressed the flooding source South Creek. That table...

2011-03-14

285

77 FR 73398 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Bailey Ditch (backwater effects...Incorporated Areas'' addressed the following flooding sources: Bailey Ditch (backwater...

2012-12-10

286

76 FR 26981 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Cache Creek, Cache Creek Left...County, California'' addressed the flooding source Cache Creek Settling Basin....

2011-05-10

287

77 FR 67325 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Baraboo River, Devil's Lake...Incorporated Areas'' addressed the flooding sources: Baraboo River, Devil's...

2012-11-09

288

76 FR 45215 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Dry Run Creek, Illinois River...Incorporated Areas'' addressed the flooding source Illinois River. That table...

2011-07-28

289

76 FR 12665 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Hungry Hollow Gulch, Ice House...Incorporated Areas'' addressed the following flooding sources: Hungry Hollow Gulch, Ice...

2011-03-08

290

76 FR 26982 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Areas. Specifically, it addresses the flooding source Licking River (Cave Run Lake...Incorporated Areas,'' addressed the flooding source Licking River (Cave Run...

2011-05-10

291

76 FR 43637 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...The table provided here represents the flooding sources, location of referenced elevations...Specifically, it addresses the following flooding sources: Bailey Branch (backwater effects...Incorporated Areas'' addressed the flooding source Cumberland River. That...

2011-07-21

292

77 FR 73324 - Final Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...Elevation in feet (NAVD) State City/town/county Source of flooding...the Chesterfield *20 County/City of Colonial Heights/City of Petersburg boundary. Blackman...of * 185 Unincorporated Areas of Hull Street (U.S. Route...

2012-12-10

293

Accuracy of Gravity Gradients at Elevations.  

National Technical Information Service (NTIS)

Formulas are derived for the computation of accuracy of the three components of gravity disturbance gradient at elevations as determined from surface anomalies. The earth is replaced by its tangent plane. (Author)

E. Groten

1965-01-01

294

75 FR 61371 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...or to show evidence of having in effect in order to qualify or remain qualified for participation in the National Flood Insurance Program (NFIP). In addition, these elevations, once finalized, will be used by insurance agents and...

2010-10-05

295

Evaluation of Experimental Data from the Gains Balloon GPS Surface Reflection Instrument  

NASA Technical Reports Server (NTRS)

The GPS Surface Reflection Instrument was integrated as an experiment on the GAINS (Global Airocean IN-situ System) 48-hour balloon mission flown in June 2002. The data collected by similar instruments in the past has been used to measure sea state from which ocean surface winds can be accurately estimated. The GPS signal has also been shown to be reflected from wetland areas and even from subsurface moisture. The current version of the instrument has been redesigned to be more compact, use less power, and withstand a greater variation in environmental conditions than previous versions. This instrument has also incorporated a new data collection mode to track 5 direct satellites (providing a continuous navigation solution) and multiplex the remaining 7 channels to track the reflected signal of the satellite tracked in channel 0. The new software mode has been shown to increase the signal to noise ratio of the collected data and enhance the science return of the instrument. During the GAINS balloon flight over the Northwest US, the instrument measured surface reflections as they were detected over the balloon's ground track. Since ground surface elevations in this area vary widely from the WGS-84 ellipsoid altitude, the instrument software has been modified to incorporate a surface altitude correction based on USGS 30-minute Digital Elevation Models. Information presented will include facts about instrument design goals, data collection methodologies and algorithms, and will focus on results of the science data analyses for the mission.

Ganoe, George G.; Johnson, Thomas A.; Somero, John Ryan

2002-01-01

296

Elevations and Distances in the United States  

NSDL National Science Digital Library

Using surveys and topographic maps, the United States Geological Survey (USGS) has determined distances between points and elevations of features, and put them into a data format at this website. Elevations of the 50 largest cities, highest and lowest points in each state, summits over 14,000 feet, summits east of the Rocky Mountains, geographic centers of each state, length of US boundaries, and extreme distances are covered at this site.

297

HYDRO 1K Elevation Derivative Database  

NSDL National Science Digital Library

The Earth Resources Observation Systems' Data Center at the US Geological Survey developed this database from the 30 arc-second digital elevation model of the world. The database contains six raster data sets in tar file format: elevation data, shaded relief, slope, aspect, flow direction, and flow accumulation; and two vector data sets in tar or gzipped ARC/INFO Export file formats: drainage basins and streams.

1998-01-01

298

Energy considerations in the partial space elevator  

NASA Astrophysics Data System (ADS)

The space elevator has been proposed as an alternate method for space transportation. A partial elevator is composed of a tether of several hundreds of kilometres, held vertically in tension between two end masses, with its centre of orbit placed at the geosynchronous orbit. A spacecraft can dock at the lower end, and then use the climber on the elevator to ascend to higher altitudes. In this paper, energy calculations are performed, to determine whether a partial elevator can provide sufficient savings in operational costs, compared to the traditional rocket-powered launch. The energy required to launch a spacecraft from a Low Earth Orbit (LEO) to the geostationary orbit (GEO) is calculated for two trajectories. In the first trajectory, the spacecraft travels from LEO to GEO via a Hohmann transfer. In the second trajectory, the spacecraft travels from LEO to the lower end of the partial space elevator with a Hohmann transfer, and then uses the elevator to climb to GEO. The total energy required is compared between the two trajectories. The effects of tether length, spacecraft-to-climber mass ratio, altitude of LEO, and tether material are investigated.

Woo, Pamela; Misra, Arun K.

2014-06-01

299

Are videogame training gains specific or general?  

PubMed Central

Many recent studies using healthy adults document enhancements in perception and cognition from playing commercial action videogames (AVGs). Playing action games (e.g., Call of Duty, Medal of Honor) is associated with improved bottom-up lower-level information processing skills like visual-perceptual and attentional processes. One proposal states a general improvement in the ability to interpret and gather statistical information to predict future actions which then leads to better performance across different perceptual/attentional tasks. Another proposal claims all the tasks are separately trained in the AVGs because the AVGs and laboratory tasks contain similar demands. We review studies of action and non-AVGs to show support for the latter proposal. To explain transfer in AVGs, we argue that the perceptual and attention tasks share common demands with the trained videogames (e.g., multiple object tracking (MOT), rapid attentional switches, and peripheral vision). In non-AVGs, several studies also demonstrate specific, limited transfer. One instance of specific transfer is the specific enhancement to mental rotation after training in games with a spatial emphasis (e.g., Tetris). In contrast, the evidence for transfer is equivocal where the game and task do not share common demands (e.g., executive functioning). Thus, the “common demands” hypothesis of transfer not only characterizes transfer effects in AVGs, but also non-action games. Furthermore, such a theory provides specific predictions, which can help in the selection of games to train human cognition as well as in the design of videogames purposed for human cognitive and perceptual enhancement. Finally this hypothesis is consistent with the cognitive training literature where most post-training gains are for tasks similar to the training rather than general, non-specific improvements.

Patterson, Michael D.

2014-01-01

300

Are videogame training gains specific or general?  

PubMed

Many recent studies using healthy adults document enhancements in perception and cognition from playing commercial action videogames (AVGs). Playing action games (e.g., Call of Duty, Medal of Honor) is associated with improved bottom-up lower-level information processing skills like visual-perceptual and attentional processes. One proposal states a general improvement in the ability to interpret and gather statistical information to predict future actions which then leads to better performance across different perceptual/attentional tasks. Another proposal claims all the tasks are separately trained in the AVGs because the AVGs and laboratory tasks contain similar demands. We review studies of action and non-AVGs to show support for the latter proposal. To explain transfer in AVGs, we argue that the perceptual and attention tasks share common demands with the trained videogames (e.g., multiple object tracking (MOT), rapid attentional switches, and peripheral vision). In non-AVGs, several studies also demonstrate specific, limited transfer. One instance of specific transfer is the specific enhancement to mental rotation after training in games with a spatial emphasis (e.g., Tetris). In contrast, the evidence for transfer is equivocal where the game and task do not share common demands (e.g., executive functioning). Thus, the "common demands" hypothesis of transfer not only characterizes transfer effects in AVGs, but also non-action games. Furthermore, such a theory provides specific predictions, which can help in the selection of games to train human cognition as well as in the design of videogames purposed for human cognitive and perceptual enhancement. Finally this hypothesis is consistent with the cognitive training literature where most post-training gains are for tasks similar to the training rather than general, non-specific improvements. PMID:24782722

Oei, Adam C; Patterson, Michael D

2014-01-01

301

Elevation Change of Greenland's Jakobshavn Glacier from ICESat, IceBridge Altimetry and TerraSAR-X DEMs  

NASA Astrophysics Data System (ADS)

The recent accelerated ice mass loss of the Greenland ice sheet, and its outlet glacier in particular, has been widely documented. The Jakobshavn Isbrae/Glacier is one of the fastest melting and retreating glaciers in Greenland. Recent observations from the laser altimetry mission ICESat (2003-2009) and the airborne campaigns of the IceBridge project (2009-2011) were used to determine Jakobshavn's total elevation change for those time periods as well as annual elevation change rates. TerraSAR-X data acquired in 2009 were processed to form 3 m horizontal resolution digital elevation models (DEM), which were constrained using ICESat measurements. The elevation change results confirm previously determined rates of several decimeters per year of elevation loss. More specifically, while the outlet glacier shows elevation loss of up to several meters per year, the higher elevation areas of the ice sheet exhibit only a few decimeters per year loss and even elevation gain for some years. The study area below 1500 m elevation shows elevation change rates between -0.5 to -2.5 m/yr, the higher elevation area exhibits a much decreased rate between +0.34 and -0.55 m/yr. The Jakobshavn outlet glacier showed a consistently increasing elevation change rate of -3.0 to -5.0 m/yr between 2003 and 2011. It demonstrates that both ICESat and IceBridge observations allow for the accurate estimation of elevation change rates with uncertainties of less than 0.5 m/yr standard deviation. The major contributor to the uncertainty is the slope correction needed to project two footprints at different epochs onto a common location. The slope correction was applied based on the DEMs from ICESat and TerraSAR-X data or the IceBridge slope measurements. Both ICESat and IceBridge observations are able to demonstrate the variations in annual and seasonal elevation change rates exceeding 0.5 m/yr, a rate which is by far exceeded for low-elevation areas below 1500 m. By having an improved understanding of annual and seasonal variability of elevation change, the mass balance of the Jakobshavn glacier can be better assessed towards quantifying its contribution to sea level change.otal elevation change between early-summer 2009 and early-summer 2011 from IceBridge data along the flight tracks.

Qi, W.; Braun, A.

2012-12-01

302

Lunar transportation scenarios utilising the Space Elevator  

NASA Astrophysics Data System (ADS)

The Space Elevator (SE) concept has begun to receive an increasing amount of attention within the space community over the past couple of years and is no longer widely dismissed as pure science fiction. In light of the renewed interest in a, possibly sustained, human presence on the Moon and the fact that transportation and logistics form the bottleneck of many conceivable lunar missions, it is interesting to investigate what role the SE could eventually play in implementing an efficient Earth to Moon transportation system. The elevator allows vehicles to ascend from Earth and be injected into a trans-lunar trajectory without the use of chemical thrusters, thus eliminating gravity loss, aerodynamic loss and the need of high thrust multistage launch systems. Such a system therefore promises substantial savings of propellant and structural mass and could greatly increase the efficiency of Earth to Moon transportation. This paper analyzes different elevator-based trans-lunar transportation scenarios and characterizes them in terms of a number of benchmark figures. The transportation scenarios include direct elevator-launched trans-lunar trajectories, elevator-launched trajectories via L1 and L2, as well as launch from an Earth-based elevator and subsequent rendezvous with lunar elevators placed either on the near or on the far side of the Moon. The benchmark figures by which the different transfer options are characterized and evaluated include release radius (RR), required ?v, transfer times as well as other factors such as accessibility of different lunar latitudes, frequency of launch opportunities and mission complexity. The performances of the different lunar transfer options are compared with each other as well as with the performance of conventional mission concepts, represented by Apollo.

Engel, Kilian A.

2005-07-01

303

Elevated Vitamin B12 Levels in Autoimmune Lymphoproliferative Syndrome Attributable to Elevated Haptocorrin in Lymphocytes  

PubMed Central

Objective Identify the etiology of elevated B12 in autoimmune lymphoproliferative syndrome (ALPS). Design Peripheral blood of ALPS patients with elevated B12 and controls were evaluated. Results Total and holo-haptocorrin (HC) levels were 26- and 23-fold higher in ALPS patients, respectively. No abnormal B12-binding proteins were found. Western blot revealed HC in lymphocyte lysates only from ALPS patients. Conclusion Elevated concentrations of B12 found in ALPS patients were due to increased lymphocyte expression of HC.

Bowen, Raffick A.R.; Dowdell, Kennichi C.; Dale, Janet K.; Drake, Steven K.; Fleisher, Thomas A.; Hortin, Glen L.; Remaley, Alan T.; Nexo, Ebba; Rao, V. Koneti

2012-01-01

304

Quantification of glacier elevation changes using ICESat and SRTM elevation data in the Upper Indus Basin  

NASA Astrophysics Data System (ADS)

Recent studies carried out in the Karakoram Himalayas suggest an expansion of glaciers. Many studies conducted in the Himalayan region have focused on monitoring changes in the aerial extent of individual glaciers from remotely sensed data or through field surveys. Limited work, however, has been done in this region to estimate glacier volume changes using measurements of elevation change over time, particularly at a large scale. Here we used Ice, Cloud and Land Elevation Satellite (ICESat) and the Shuttle Radar Topography Mission (SRTM) data to estimate glacier elevation changes within the Upper Indus River Basin (UIB). The elevation changes were estimated within snow-covered and clean-ice zones which were delineated using historic Land Remote-Sensing Satellite (Landsat) images. ICESat/GLA06 elevations data from spring campaigns, release 28 were used to estimate ice elevation changes for the period of 2004-2008 relative to 2000. The accuracy of elevation change was assessed by analyzing non-glacier elevation difference points within different categories of a Terrain Ruggedness Index (TRI). This comparison showed that elevations precision decreased with increasing TRI, so using TRI to categorize glacier areas helps to identify data points with higher accuracy. Our analysis of elevation changes estimated from the ICESat altimeter identified two clear patterns in elevation changes. Firstly, glaciers in the northern half of the Upper Indus valley have thickened in the last decade, while those in the southern sub-watersheds are thinning. Secondly, glacier thickening occurred on the higher elevation snow-covered ice zone, while more thinning rates were observed within the clean ice zone for all sub-watersheds of the UIB, except in the Hunza river basin. Such results showed the potential of ICESat data for assessing relief changes on mountain glaciers and could be used in the estimation of glacier mass balance at higher temporal resolutions.

Naz, B. S.; Bowling, L. C.; Crawford, M. M.

2010-12-01

305

Training children in pedestrian safety: distinguishing gains in knowledge from gains in safe behavior.  

PubMed

Pedestrian injuries contribute greatly to child morbidity and mortality. Recent evidence suggests that training within virtual pedestrian environments may improve children's street crossing skills, but may not convey knowledge about safety in street environments. We hypothesized that (a) children will gain pedestrian safety knowledge via videos/software/internet websites, but not when trained by virtual pedestrian environment or other strategies; (b) pedestrian safety knowledge will be associated with safe pedestrian behavior both before and after training; and (c) increases in knowledge will be associated with increases in safe behavior among children trained individually at streetside locations, but not those trained by means of other strategies. We analyzed data from a randomized controlled trial evaluating pedestrian safety training. We randomly assigned 240 children ages 7-8 to one of four training conditions: videos/software/internet, virtual reality (VR), individualized streetside instruction, or a no-contact control. Both virtual and field simulations of street crossing at 2-lane bi-directional mid-block locations assessed pedestrian behavior at baseline, post-training, and 6-month follow-up. Pedestrian knowledge was assessed orally on all three occasions. Children trained by videos/software/internet, and those trained individually, showed increased knowledge following training relative to children in the other groups (ps < 0.01). Correlations between pedestrian safety knowledge and pedestrian behavior were mostly non-significant. Correlations between change in knowledge and change in behavior from pre- to post-intervention also were non-significant, both for the full sample and within conditions. Children trained using videos/software/internet gained knowledge but did not change their behavior. Children trained individually gained in both knowledge and safer behavior. Children trained virtually gained in safer behavior but not knowledge. If VR is used for training, tools like videos/internet might effectively supplement training. We discovered few associations between knowledge and behavior, and none between changes in knowledge and behavior. Pedestrian safety knowledge and safe pedestrian behavior may be orthogonal constructs that should be considered independently for research and training purposes. PMID:24573688

Schwebel, David C; McClure, Leslie A

2014-06-01

306

The effects of neural gain on attention and learning  

PubMed Central

Attention is commonly thought to be manifest through local variations in neural gain. However, what would be the effects of brain-wide changes in gain? Here, we hypothesize that global fluctuations in gain modulate the breadth of attention, and thus, the degree to which processing is focused on aspects of the environment to which one is predisposed to attend. In accordance with this hypothesis, we show that measures of pupil diameter, which are thought to track levels of LC-NE activity and neural gain, are correlated with the degree to which learning is focused on stimulus dimensions that individual human participants are more predisposed to process. In support of our interpretation of this effect in terms of global changes in gain, we further show that the measured pupillary and behavioral variables are strongly correlated with global changes in the strength and clustering of functional connectivity, as brain-wide fluctuations of gain would predict.

Eldar, Eran; Cohen, Jonathan D.; Niv, Yael

2013-01-01

307

WFC3 Cycle 20 Proposal 13168: UVIS Gain  

NASA Astrophysics Data System (ADS)

This report summarizes the absolute gain results from HST Cycle 20 proposal 13168: UVIS Gain and compares results to previous on orbit and ground measurements. The gain values were measured for each quadrant using internal calibration unbinned flat field data with nominal gain setting (1.5 e-/DN). The gain for cycle 20 was measured twice during the cycle; once in December 2012 and again in June 2013. Measurements from the both epochs of data yielded gain values of: 1.56, 1.55, 1.58, and 1.57 e-/DN with errors 0.01 e-/DN, for quadrants A, B, C, and D, respectively. These measurements are within 1-2% of previous values from TV3 through Cycle 19 and thus remain stable.

Gunning, H.; Baggett, S.

2014-04-01

308

Space Elevator Concept Considered a Reality  

NASA Technical Reports Server (NTRS)

The `once upon a time' science fiction concept of a space elevator has been envisioned and studied as a real mass transportation system in the latter part of the 21st century. David Smitherman of NASA's Marshall Space Flight Center's Advanced Projects Office has compiled plans for such an elevator. The space elevator concept is a structure extending from the surface of the Earth to geostationary Earth orbit (GEO) at 35,786 km in altitude. The tower would be approximately 50 km tall with a cable tethered to the top. Its center mass would be at GEO such that the entire structure orbits the Earth in sync with the Earth's rotation maintaining a stationary position over its base attachment at the equator. Electromagnetic vehicles traveling along the cable could serve as a mass transportation system for transporting people, payloads, and power between space and Earth. This illustration by artist Pat Rawling shows the concept of a space elevator as viewed from the geostationary transfer station looking down the length of the elevator towards the Earth.

2000-01-01

309

Design and Deployment of a Space Elevator  

NASA Astrophysics Data System (ADS)

The space elevator was first proposed in the 1960s as a method of getting into space. The initial studies of a space elevator outlined the basic concept of a cable strung between Earth and space but concluded that no material available at the time had the required properties to feasibly construct such a cable. With the discovery of carbon nanotubes in 1991 it is now possible to realistically discuss the construction of a space elevator. Although currently produced only in small quantities, carbon nanotubes appear to have the strength-to-mass ratio required for this endeavor. However, fabrication of the cable required is only one of the challenges in construction of a space elevator. Powering the climbers, surviving micrometeor impacts, lightning strikes and low-Earth-orbit debris collisions are some of the problems that are now as important to consider as the production of the carbon nanotube cable. We consider various aspects of a space elevator and find each of the problems that this endeavor will encounter can be solved with current or near-future technology.

Edwards, Bradley C.

2000-11-01

310

Feasibility Study of a Stratospheric Elevator  

NASA Astrophysics Data System (ADS)

As a first step in the development of a space elevator, we focused on the stratospheric platform that would be used as a relay station of communication and high-resolution earth observation base at 20~30 km altitude. We propose a new system for connecting the platform to the ground by a tether that would allow the payload to be transported by a climber moving along the tether. We call this system a stratospheric elevator. The stratospheric elevator offers not only the chance to verify the space elevator technology but also the chance to extend the life of the platform by making its maintenance easy. The result of our initial study of the system showed that we can build a stratospheric elevator using currently available materials and technology. The total tether system, including a 200 kg payload and a 200 kg climber, would weigh about 2 tons with considering the effect of the high-speed airstream when we built the system at 20 km altitude, and a platform of about 80 m diameter could sustain the total system.

Yamagiwa, Yoshiki; Nakata, Masafumi; Miwa, Toru; Matsui, Makoto

311

Amplified Warming Rates in High Elevation Regions  

NASA Astrophysics Data System (ADS)

We use ground-based and satellite-retrieved observations in conjunction with output from global climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to determine whether warming rates in high elevation regions are significantly different than in their lower elevation surroundings. In addition, for regions where there is enhanced warming at higher elevations, we investigate several of the potential mechanisms that may contribute to this enhancement. For the mid-latitudes in the Northern Hemisphere, the multi-model ensemble indicates that warming rates during the 21st century will be enhanced at high elevations relative to their lower elevation counterparts at the same latitude. This effect is most pronounced for daily minimum temperatures during the cold season in the Tibetan Plateau/Himalayan region. A neural network analysis is used to identify and quantify some of the potential mechanisms responsible for enhanced warming rates, including the effects of variables such as atmospheric water vapor, clouds, snow cover, and aerosols on the radiation and surface heat budgets. We also demonstrate that satellite retrievals can be used to expand the often sparse ground-based observations in such regions and that they provide the correct relationships between variables. Please fill in your abstract text.

Miller, James; Naud, Catherine; Chen, Yonghua; Ghatak, Debjani; Rangwala, Imtiaz; Sinsky, Eric

2014-05-01

312

7 CFR 800.25 - Required elevator and merchandising records.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 2010-01-01 false Required elevator and merchandising records. 800.25 Section 800.25 Agriculture ...Access to Facilities § 800.25 Required elevator and merchandising records. (a) Elevator and merchandiser...

2010-01-01

313

7 CFR 800.25 - Required elevator and merchandising records.  

Code of Federal Regulations, 2010 CFR

...2009-01-01 2009-01-01 false Required elevator and merchandising records. 800.25 Section 800.25 Agriculture ...Access to Facilities § 800.25 Required elevator and merchandising records. (a) Elevator and merchandiser...

2009-01-01

314

2. GLF, north elevation. Visible from left to right ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. GLF, north elevation. Visible from left to right - elevator C, and B, feed mill in foreground, and former molasses storage tanks. - Cooperative Grange League Federation Elevator, 385 Ganson Street, Buffalo, Erie County, NY

315

46 CFR 116.438 - Stairtowers, stairways, ladders, and elevators.  

Code of Federal Regulations, 2010 CFR

...ladders, elevators, and landings within machinery spaces and cargo holds...with severe space constraints...stairway or elevator exceeds one deck...enclosure. In spaces containing a...stairways or elevators need not...

2010-10-01

316

46 CFR 72.05-20 - Stairways, ladders, and elevators.  

Code of Federal Regulations, 2010 CFR

...Stairways, ladders, and elevators within main machinery spaces or cargo holds are...Stairways, ladders, and elevators within main machinery spaces and cargo holds shall...provided the stairway or elevator serves only the space and the balcony...

2009-10-01

317

46 CFR 116.438 - Stairtowers, stairways, ladders, and elevators.  

Code of Federal Regulations, 2010 CFR

...ladders, elevators, and landings within machinery spaces and cargo holds...with severe space constraints...stairway or elevator exceeds one deck...enclosure. In spaces containing a...stairways or elevators need not...

2009-10-01

318

49 CFR 213.59 - Elevation of curved track; runoff.  

Code of Federal Regulations, 2010 CFR

...Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Geometry § 213.59 Elevation of curved track; runoff. (a) If a curve is elevated, the full elevation shall be...

2009-10-01

319

19. View of elevated Mainline structure looking Southeast ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

19. View of elevated Mainline structure - looking Southeast - across Franklin Square park with the Franklin Square House in the background. - Boston Elevated Railway, Elevated Mainline, Washington Street, Boston, Suffolk County, MA

320

High-gain observers in nonlinear feedback control  

Microsoft Academic Search

The theory of high-gain observers has been developed for about twenty years. This paper is a brief introduction to high-gain observers in nonlinear feedback control, with emphasis on the peaking phenomenon and the role of control saturation in dealing with it. The paper surveys recent results on the nonlinear separation principle, conditional servo compensators, extended high-gain observers, performance in the

Hassan K. Khalil

2008-01-01

321

An adaptive high-gain observer for nonlinear systems  

Microsoft Academic Search

In this paper the authors provide a solution to the noise sensitivity of high-gain observers. The resulting nonlinear observer possesses simultaneously (1) extended Kalman filter’s good noise filtering properties, and (2) the reactivity of the high-gain extended Kalman filter with respect to large perturbations.The authors introduce innovation as the quantity that drives the gain adaptation. They prove a general convergence

Nicolas Boizot; Eric Busvelle; Jean-Paul Gauthier

2010-01-01

322

High-gain observers in nonlinear feedback control  

Microsoft Academic Search

Summary form only given. The theory of high-gain observers has been developed for about twenty years. This talk is a brief introduction to high-gain observers in nonlinear feedback control, with emphasis on the peaking phenomenon and the role of control saturation in dealing with it. The talk surveys recent results on the nonlinear separation principle, extended high-gain observers, performance in

Hassan K. Khalil

2009-01-01

323

Design of a high-gain flux-compression generator  

Microsoft Academic Search

The current gain of a high gain, high explosive helical magnetic-flux-compression generator (HEG) is limited both by nonuniformities in stator expansion and by armature-stator misalignment. Three goals were explored: (1) an output current of at least 2 MA with a current gain greater than 1000 to drive a 150- to 300-nH load; (2) a generator with an acceptably small volume

P. A. Pincosy; D. K. Abe; J. B. Chase

1989-01-01

324

Liquid crystal as laser medium with tunable gain spectra.  

PubMed

Amplified spontaneous emission intensity and gain spectra in polarized light have been measured in a dye doped nematic liquid crystal for different orientation of its optical axis and pump intensity. A possibility for switching the gain of the liquid crystal by an external electric field is shown experimentally. The liquid crystal materials with field controlled gain can be used in microlasers and light micro-amplifiers in both planar and waveguiding geometry. PMID:18545366

Blinov, L M; Cipparrone, G; Lazarev, V V; Pagliusi, P; Rugiero, T

2008-04-28

325

Gain enhancement in a XeCl-pumped Raman amplifier  

SciTech Connect

A comparison of the theoretical predictions of a multimode broadband model with the experimentally measured gain enhancement in a Raman amplifier is presented. The results show that the multimode theory with fixed and totally random phases is in agreement with the data obtained from an excimer-laser-pumped Raman amplifier. Additionally, this theory indicates that the correlated gain can be larger than the gain for a monochromatic laser, as might be expected for a model with amplitude modulation.

Rifkin, J.; Bernt, M.L.; MacPherson, D.C.; Carlsten, J.L.

1988-08-01

326

Effects of prescribed burning on marsh-elevation change and the risk of wetland loss  

USGS Publications Warehouse

Marsh-elevation change is the net effect of biophysical processes controlling inputs versus losses of soil volume. In many marshes, accumulation of organic matter is an important contributor to soil volume and vertical land building. In this study, we examined how prescribed burning, a common marsh-management practice, may affect elevation dynamics in the McFaddin National Wildlife Refuge, Texas by altering organic-matter accumulation. Experimental plots were established in a brackish marsh dominated by Spartina patens, a grass found throughout the Gulf of Mexico and Atlantic marshes. Experimental plots were subjected to burning and nutrient-addition treatments and monitored for 3.5 years (April 2005 – November 2008). Half of the plots were burned once in 2006; half of the plots were fertilized seasonally with nitrogen, phosphorus, and potassium. Before and after the burns, seasonal measurements were made of soil physicochemistry, vegetation structure, standing and fallen plant biomass, aboveground and belowground production, decomposition, and accretion and elevation change (measured with Surface Elevation Tables (SET)). Movements in different soil strata (surface, root zone, subroot zone) were evaluated to identify which processes were contributing to elevation change. Because several hurricanes occurred during the study period, we also assessed how these storms affected elevation change rates. The main findings of this study were as follows: 1. The main drivers of elevation change were accretion on the marsh surface and subsurface movement below the root zone, but the relative influence of these processes varied temporally. Prior to Hurricanes Gustav and Ike (September 2008), the main driver was subsurface movement; after the hurricane, both accretion and subsurface movement were important. 2. Prior to Hurricanes Gustav and Ike, rates of elevation gain and accretion above a marker horizon were higher in burned plots compared to nonburned plots, whereas nutrient addition had no detectable influence on elevation dynamics. 3. Burning decreased standing and fallen plant litter, reducing fuel load. Hurricanes Gustav and Ike also removed fallen litter from all plots. 4. Aboveground and belowground production rates varied annually but were unaffected by burning and nutrient treatments. 5. Decomposition (of a standard cellulose material) in upper soil layers was increased in burned plots but was unaffected by nutrient treatments. 6. Soil physicochemistry was unaffected by burning or nutrient treatments. 7. The elevation deficit (difference between rate of submergence and vertical land development) prior to hurricanes was less in burned plots (6.2 millimeters per year [mm yr-1]) compared to nonburned plots (7.2 mm yr-1). 8. Storm sediments delivered by Hurricane Ike raised elevations an average of 7.4 centimeters (cm), which countered an elevation deficit that had accrued over 11 years. Our findings provide preliminary insights into elevation dynamics occurring in brackish marshes of the Texas Chenier Plain under prescribed fire management. The results of this study indicate that prescribed burning conducted at 3- to 5-year intervals is not likely to negatively impact the long-term sustainability of S. patens-dominated brackish marshes at McFaddin National Wildlife Refuge and may offset existing elevation deficits by ? 1 mm yr-1. The primary drivers of elevation change varied in time and space, leading to a more complex situation in terms of predicting how disturbances may alter elevation trajectories. The potential effect of burning on elevation change in other marshes will depend on several site-specific factors, including geomorphic/ sedimentary setting, tide range, local rate of relative sea level rise, plant species composition, additional management practices (for example, for flood control), and disturbance types and frequency (for example, hurricanes or herbivore grazing). Increasing the scope of inference would require installation of SETs in replicate marshes undergoing different prescribed fire intervals

McKee, Karen L.; Grace, James B.

2012-01-01

327

Gain-clamped fibre amplifier using an ASE end reflector  

NASA Astrophysics Data System (ADS)

All-optical gain clamping in an erbium-doped fibre amplifier is demonstrated using a broadband fibre Bragg grating that reflects the amplified spontaneous emission centred at 1530 nm with a 14 nm bandwidth. Experiments on an eight-channel wavelength division multiplexing system show promise when the gain is clamped at 21 dB. Gain flatness is less than 0.6 dB across all channels and gain variation is about 0.2 dB over the input signal power range.

Mahdi, M. A.; Mahamd Adikan, F. R.; Poopalan, P.; Selvakennedy, S.; Chan, W. Y.; Ahmad, H.

2000-04-01

328

Diverse Women's Beliefs about Weight Gain in Pregnancy  

PubMed Central

This research was conducted to describe ethnically diverse new mothers’ perceptions of gestational weight gain. Forty-nine low-income women of diverse racial and ethnic origins who birthed an infant within the past year completed a semi-structured interview in a pediatric clinic waiting room. Interviews were designed to elicit views on gestational weight gain, including expectations and perceived consequences. Data were analyzed using content analysis techniques. Women believed that others like themselves were concerned about pregnancy weight gain. Many focused on the effects of insufficient pregnancy weight gain on the infant but were not aware of the infant risks of excessive gain. Several had inaccurate knowledge of appropriate gestational weight gain, and many suggested an amount below current recommendations. One-third of the women believed women will weigh more following pregnancy, yet others assumed that even with excessive weight gain there would be a return to pre-pregnant weight following pregnancy. Pregnancy-related weight gain is disturbing to women. Health care providers have the opportunity to intervene by acknowledging these concerns and providing information and support to help women make positive choices and achieve appropriate weight gain.

Groth, Susan W.; Kearney, Margaret H.

2009-01-01

329

The physics of the space elevator  

NASA Astrophysics Data System (ADS)

A space elevator is a tall tower rising from a point on the Earth's equator to a height well above a geostationary orbit, where it terminates in a counterweight. Although the concept is more than a century old, it was only with the discovery of carbon nanotubes that it began to receive serious scientific attention. NASA commissioned a study of the space elevator in the late 1990s that examined the feasibility of such a structure and explored many of its applications. I explain the basic mechanical principles underlying the construction of a space elevator and discuss several of its applications: the transport of payload into space and the launching of spacecraft on voyages to other planets.

Aravind, P. K.

2007-02-01

330

Vertical vibration analysis for elevator compensating sheave  

NASA Astrophysics Data System (ADS)

Most elevators applied to tall buildings include compensating ropes to satisfy the balanced rope tension between the car and the counter weight. The compensating ropes receive tension by the compensating sheave, which is installed at the bottom space of the elevator shaft. The compensating sheave is only suspended by the compensating ropes, therefore, the sheave can move vertically while the car is traveling. This paper shows the elevator dynamic model to evaluate the vertical motion of the compensating sheave. Especially, behavior in emergency cases, such as brake activation and buffer strike, was investigated to evaluate the maximum upward motion of the sheave. The simulation results were validated by experiments and the most influenced factor for the sheave vertical motion was clarified.

Watanabe, Seiji; Okawa, Takeya; Nakazawa, Daisuke; Fukui, Daiki

2013-07-01

331

Advanced composite elevator for Boeing 727 aircraft  

NASA Technical Reports Server (NTRS)

Detail design activities are reported for a program to develop an advanced composites elevator for the Boeing 727 commercial transport. Design activities include discussion of the full scale ground test and flight test activities, the ancillary test programs, sustaining efforts, weight status, and the production status. Prior to flight testing of the advanced composites elevator, ground, flight flutter, and stability and control test plans were reviewed and approved by the FAA. Both the ground test and the flight test were conducted according to the approved plan, and were witnessed by the FAA. Three and one half shipsets have now been fabricated without any significant difficulty being encountered. Two elevator system shipsets were weighed, and results validated the 26% predicted weight reduction. The program is on schedule.

1979-01-01

332

23. VIEW SECOND FLOOR, ELEVATOR SHAFT SAFETY NET ACCESS, NORTHWEST ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. VIEW SECOND FLOOR, ELEVATOR SHAFT SAFETY NET ACCESS, NORTHWEST ELEVATOR LOADING DOOR. - Bates Manufacturing Company, Storehouse, Northeast corner of Chestnut Street & Hines Alley, Lewiston, Androscoggin County, ME

333

Effective Gain Measurement in Quantum Cascade Lasers: A new method to measure gain in Quantum Cascade Lasers  

NSDL National Science Digital Library

Gain and Loss are the fundamental factors contributing to laser effectiveness. Simply put, the gain is the light produced by stimulated emission and loss is then the light lost. This can happen if a photon hits an electron in a low energy level state and the electron absorbs the energy and moves to a higher energy level state. It can also happen when light escapes the laser cavity. Lasing is the condition when the gain exceeds the loss. It is very important to know the gain to see how effective your laser really is. The traditional Hakki-Paoli Method was found to be ineffective for measuring gain in quantum cascade lasers. A new, more effective method of measuring gain in quantum cascade lasers was developed and tested.

Haslam, Bryan

2005-08-05

334

Forest succession at elevated CO2  

SciTech Connect

We tested hypotheses concerning the response of forest succession to elevated CO2 in the FACTS-1 site at the Duke Forest. We quantified growth and survival of naturally recruited seedlings, tree saplings, vines, and shrubs under ambient and elevated CO2. We planted seeds and seedlings to augment sample sites. We augmented CO2 treatments with estimates of shade tolerance and nutrient limitation while controlling for soil and light effects to place CO2 treatments within the context of natural variability at the site. Results are now being analyzed and used to parameterize forest models of CO2 response.

Clark, James S.; Schlesinger, William H.

2002-02-01

335

1. SOUTH (FRONT) ELEVATION, SHOWING FRONT ELEVATIONS OF 501511 14th ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. SOUTH (FRONT) ELEVATION, SHOWING FRONT ELEVATIONS OF 501-511 14th STREET (THE LOCKER ROOM) (HABS No. DC-356) TO WEST AND WILLIAM J. STONE BUILDING (FRISCO'S) TO EAST. - Loughran Building, 1347 E Street Northwest, Washington, District of Columbia, DC

336

Gains and overexpression identify DEK and E2F3 as targets of chromosome 6p gains in retinoblastoma  

Microsoft Academic Search

The paediatric eye tumour retinoblastoma is initiated by inactivation of RB1, a tumour suppressor on chromosome 13q. In addition to RB1 loss, many retinoblastomas show other genetic alterations including gains on chromosomes 6p21–pter and 1q31–q32. Recently, the minimal region of gains on chromosome 6 was narrowed to band p22. We examined genomic gains and expression changes in primary retinoblastomas to

Corinna Grasemann; Sandrine Gratias; Harald Stephan; Andreas Schüler; Alexander Schramm; Ludger Klein-Hitpass; Harald Rieder; Stephanie Schneider; Ferdinand Kappes; Angelika Eggert; Dietmar R Lohmann

2005-01-01

337

Waveguides with a silver lining: Low threshold gain and giant modal gain in active cylindrical and coaxial plasmonic devices  

NASA Astrophysics Data System (ADS)

Loss is one of the most substantial impediments to integrated plasmonics. In this paper, we present a theoretical analysis of active cylindrical plasmon slot waveguides, including their modal characteristics, gain spectra, and lasing threshold. Particular attention is given to two classes of waveguide geometries composed of various core/channel/cladding materials: a dielectric/dielectric/metal (DDM) waveguide and a metal/dielectric/metal (MDM) waveguide. Using empirically determined optical constants, we systematically study the dispersion, propagation length, threshold gain, modal gain, and confinement factor of these slot structures. For DDM waveguides, we show that introducing the gain in the channel rather than the core is of paramount importance for reduced threshold gain and increased modal gain. Confinement factor enhancement is even more pronounced in MDM waveguides, where modal gain can exceed threshold gain by 10× to 100× across visible and near-infrared frequencies. By carefully tuning the core/channel relative dimensions along with the lasing frequency, we show that threshold gain as low as 500 cm-1 is achievable in cylindrical plasmonic devices with overall diameters less than 200 nm. Our results indicate the promise of plasmonic slot structures for low-loss optical networking, and provide a roadmap for the design of optimized nanoscale plasmonic laser cavities.

Saleh, Amr A. E.; Dionne, Jennifer A.

2012-01-01

338

Gains and overexpression identify DEK and E2F3 as targets of chromosome 6p gains in retinoblastoma.  

PubMed

The paediatric eye tumour retinoblastoma is initiated by inactivation of RB1, a tumour suppressor on chromosome 13q. In addition to RB1 loss, many retinoblastomas show other genetic alterations including gains on chromosomes 6p21-pter and 1q31-q32. Recently, the minimal region of gains on chromosome 6 was narrowed to band p22. We examined genomic gains and expression changes in primary retinoblastomas to identify potential target genes in 6p22. Quantitative multiplex PCR detected copy numbers > or = 3 in 25 (33%) tumours and no gains in 31 of 76 (40%) tumours. The remaining 20 (26%) samples showed gains only at some loci, most often including E2F3 and DEK in 6p22.3. Analysis of RNA from 21 primary retinoblastomas showed that expression levels of these and some other genes in 6p22 correspond to DNA gains. However, KIF 13A, a reported candidate oncogene on 6p, was expressed at low levels or absent. Clinical manifestation of tumours with gains at all 6p22 loci was distinct in that distribution of age at diagnosis was markedly shifted to older age compared to tumours with no or partial gains. In summary, our results suggest that DEK and E2F3 are potential targets of 6p gains in retinoblastoma. PMID:16007192

Grasemann, Corinna; Gratias, Sandrine; Stephan, Harald; Schüler, Andreas; Schramm, Alexander; Klein-Hitpass, Ludger; Rieder, Harald; Schneider, Stephanie; Kappes, Ferdinand; Eggert, Angelika; Lohmann, Dietmar R

2005-09-22

339

Angiotensin AT2 Receptor Contributes towards Gender Bias in Weight Gain  

PubMed Central

Obesity is a major disease condition, in turn leading to pathological changes collectively recognized as metabolic syndrome. Recently angiotensin receptor AT2R has been associated negatively with body weight (BW) gain in male mice. However, the gender differences in AT2R and BW changes have not been studied. To understand the gender based role of AT2R involving BW changes, we fed male and female wild type (WT) and AT2R knock out (AT2KO) mice with C57BL6 background with high fat diet (HFD) for 16 weeks. The male AT2KO had higher HFD calorie intake (WT: 1280±80; AT2KO:1680±80 kcal) but gained less BW compared with the WT (WT: 13; AT2KO: 6 g). Contrary to the male animals, the female AT2KO mice with equivalent caloric intake (WT: 1424±48; AT2KO:1456±80 kcal) gained significantly more BW than the WT mice (WT: 9 g; AT2KO: 15 g). The male AT2KO on HFD displayed lower plasma insulin level, less impaired glucose tolerance (GT), and higher plasma T3 compared with WT males on HFD; whereas the female AT2KO mice on HFD showed elevated levels of plasma insulin, more impaired GT, lower plasma T3 and higher free fatty acid and hepatic triglycerides compared with WT females on HFD. Interestingly, compared with WT, AT2KO female mice had significantly lower estrogen, which was further reduced by HFD. These results suggest that AT2R in female mice via potentially regulating estrogen may have protective role against BW gain and impaired glucose tolerance and lipid metabolism.

Samuel, Preethi; Khan, Mohammad Azhar; Nag, Sourashish; Inagami, Tadashi; Hussain, Tahir

2013-01-01

340

Hurricane Wilma's impact on overall soil elevation and zones within the soil profile in a mangrove forest  

USGS Publications Warehouse

Soil elevation affects tidal inundation period, inundation frequency, and overall hydroperiod, all of which are important ecological factors affecting species recruitment, composition, and survival in wetlands. Hurricanes can dramatically affect a site's soil elevation. We assessed the impact of Hurricane Wilma (2005) on soil elevation at a mangrove forest location along the Shark River in Everglades National Park, Florida, USA. Using multiple depth surface elevation tables (SETs) and marker horizons we measured soil accretion, erosion, and soil elevation. We partitioned the effect of Hurricane Wilma's storm deposit into four constituent soil zones: surface (accretion) zone, shallow zone (0–0.35 m), middle zone (0.35–4 m), and deep zone (4–6 m). We report expansion and contraction of each soil zone. Hurricane Wilma deposited 37.0 (± 3.0 SE) mm of material; however, the absolute soil elevation change was + 42.8 mm due to expansion in the shallow soil zone. One year post-hurricane, the soil profile had lost 10.0 mm in soil elevation, with 8.5 mm of the loss due to erosion. The remaining soil elevation loss was due to compaction from shallow subsidence. We found prolific growth of new fine rootlets (209 ± 34 SE g m?2) in the storm deposited material suggesting that deposits may become more stable in the near future (i.e., erosion rate will decrease). Surficial erosion and belowground processes both played an important role in determining the overall soil elevation. Expansion and contraction in the shallow soil zone may be due to hydrology, and in the middle and bottom soil zones due to shallow subsidence. Findings thus far indicate that soil elevation has made substantial gains compared to site specific relative sea-level rise, but data trends suggest that belowground processes, which differ by soil zone, may come to dominate the long term ecological impact of storm deposit.

Whelan, K. R. T.; Smith, III, T. J.; Anderson, G. H.; Ouellette, M. L.

2009-01-01

341

Nonlinear sliding mode high-gain observers for fault estimation  

Microsoft Academic Search

A robust high gain observer for state and unknown inputs\\/faults estimations for a special class of nonlinear systems is developed in this article. Ensuring the observability of the faults\\/unknown inputs with respect to the outputs, the faults can be estimated from the sliding surface. Under a Lipschitz condition for the nonlinear part, the high gain observers are designed under some

K. C. Veluvolu; M. Y. Kim; D. Lee

2011-01-01

342

Nonlinear sliding mode high-gain observers for fault detection  

Microsoft Academic Search

A robust high gain observer for state and faults estimations for a special class of nonlinear systems is developed in this article. Ensuring the observability of the faults with respect to the outputs, the faults can be estimated from the sliding surface. Under a Lipschitz condition for the nonlinear part, the high gain observers are designed under some regularity assumptions.

K. C. Veluvolu; F. Zhe; Y. C. Soh

2010-01-01

343

High gain observer: attenuation of the peak phenomena  

Microsoft Academic Search

In many problems of estimation, the high gain technique is used to compensate for nonlinear terms in order to guarantee the convergence of the estimator. However, the use of the high gain generally generates the so-called peak phenomena (at the beginning, the estimated trajectory deviates from the desired one). We extend the observer stated in J. P. Gauthier et al.

E. H. El Yaagoubi; A. El Assoudi; H. Hammouri

2004-01-01

344

Gains and Losses from Regional Trading Agreements: A Survey  

Microsoft Academic Search

This paper provides a survey of aspects of the theory of regional trading agreements and of empirical evidence relating to estimates of country gains and losses. It begins with a survey of the predictions of trade theory relating to the gains and losses to member and to non-member countries of liberalising goods trade preferentially by the formation of a free

PETER J. LLOYD; DONALD MACLAREN

2004-01-01

345

Headwater Benefits Energy Gains (HWBEG) model description and users manual  

Microsoft Academic Search

The Headwater Benefits Energy Gains (HWBEG) Model was developed for computing energy gains in complex regulated river basins. The model requires daily data on streamflows, storage changes at reservoirs, and power generation at hydroelectric plants. Mathematical relationships are derived from these data to explain the operation of storage reservoirs and the rating of hydropower plants. The HWBEG model assembles streamflows

R. D. Perlack; A. F. Jr. Turhollow; S. M. Cohn; S. Das; C. G. Rizy; J. H. Jr. Tulley; R. D. Kraemer

1984-01-01

346

Weight Gain during Pregnancy: Importance for Maternal and Child Health  

Microsoft Academic Search

Gestational weight gain is a strong predictor of short- and long-term health outcomes for both childbearing women and their offspring. Epidemiologic studies have found that higher maternal gestational weight gains are associated with abnormalities in maternal prenatal glycemia, hypertensive disorders of pregnancy and delivery complications, along with an increased risk of postpartum weight retention, incident obesity and adverse cardiometabolic sequelae

Sharon J. Herring; Emily Oken

2010-01-01

347

What Do Students Gain by Engaging in Socioscientific Inquiry?  

Microsoft Academic Search

The question of what students gain by engaging in socioscientific inquiry is addressed in two ways. First, relevant literature is surveyed to build the case that socioscientific issues (SSI) can serve as useful contexts for teaching and learning science content. Studies are reviewed which document student gains in discipline specific content knowledge as well as understandings of the nature of

Troy D. Sadler; Sasha A. Barab; Brianna Scott

2007-01-01

348

18 CFR 11.13 - Energy gains calculations.  

Code of Federal Regulations, 2013 CFR

...of Commerce, 5285 Port Royal Road, Springfield, VA 22161. (2) If more than one headwater project provide energy gains to a downstream...downstream project or group of projects. A net loss in one calendar year will be subtracted from net gains...

2013-04-01

349

Spectrum broadening and reshaping via gain compensation of fiber amplifier  

Microsoft Academic Search

We report a novel technique to broaden and reshape the spectrum of picosecond laser pulse based on the seeder of gain switch laser diode and Yb3+-doped fiber amplifier (YDFA). From compensating the seed spectrum with the gain of YDFA, the seed pulse of 7 nm bandwidth is broadened to 20 nm, and the flat top spectral shape is obtained as

C. X. Gao; H. Liu; J. Tao; B. Caussat; W. Zhao

2009-01-01

350

A Low Noise High Gain Bandwidth Charge Sensitive Preamplifier  

Microsoft Academic Search

The concept of the charge sensitive amplifier is discussed and a novel method for obtaining a high gain amplifier stage through the use of a positive current feedback dynamic plate load is described. It is shown that under certain conditions this type of feedback can provide increased bandwidth as well as increased low frequency gain. The schematic of a preamplifier

Jack Hahn; Ralph Mayer

1962-01-01

351

Stimulated Raman gain scattering in planar dielectric waveguides  

NASA Astrophysics Data System (ADS)

We have measured the vibrational Raman spectrum of a 1.2- mu m -thick polystyrene film by using this film as an optical waveguide in a waveguide-stimulated Raman gain experiment. A gain factor of 1.3% was measured for the strong benzene mode at 1002 cm-1 . This value is in reasonable agreement with theoretical predictions.

Kanger, Johannes Sake; Tukker, Teunis W.; Otto, Cees; Greve, Jan

1996-05-01

352

Optical Gain and Stimulated Emission in Nanocrystal Quantum Dots  

Microsoft Academic Search

The development of optical gain in chemically synthesized semiconductor nanoparticles (nanocrystal quantum dots) has been intensely studied as the first step toward nanocrystal quantum dot lasers. We examined the competing dynamical processes involved in optical amplification and lasing in nanocrystal quantum dots and found that, despite a highly efficient intrinsic nonradiative Auger recombination, large optical gain can be developed at

V. I. Klimov; A. A. Mikhailovsky; Su Xu; A. Malko; J. A. Hollingsworth; C. A. Leatherdale; H.-J. Eisler; M. G. Bawendi

2000-01-01

353

A subspace method for estimating sensor gains and phases  

Microsoft Academic Search

The problem of array signal processing under model errors is studied. A signal subspace constraint is used to obtain a simple way for computing a set of sensor gains and phases consistent with a given set of DOA angles. Then the issue of uniqueness of the set of sensor gains and phases and DOA angles is addressed

V. C. Soon; L. Tong; Y. F. Huang; R. Liu

1994-01-01

354

Power gain in a quantum-dot cellular automata latch  

Microsoft Academic Search

We present an experimental demonstration of power gain in quantum-dot cellular automata (QCA) devices. Power gain is necessary in all practical electronic circuits where power dissipation leads to decay of logic levels. In QCA devices, charge configurations in quantum dots are used to encode and process binary information. The energy required to restore logic levels in QCA devices is drawn

Ravi K. Kummamuru; John Timler; Geza Toth; Craig S. Lent; Rajagopal Ramasubramaniam; Alexei O. Orlov; Gary H. Bernstein; Gregory L. Snider

2002-01-01

355

Long-period fiber-grating-based gain equalizers  

Microsoft Academic Search

Long-period fiber gratings are used to flatten the gain spectrum of erbium-doped fiber amplifiers. A broadband amplifier with >0.2-dB gain variation over 30 nm is presented. We also show that a chain of amplifiers can be equalized, leading to a bandwidth enhancement by a factor of 3. {copyright} {ital 1996 Optical Society of America.}

Ashish M. Vengsarkar; J. Renee Pedrazzani; Justin B. Judkins; Paul J. Lemaire; Neal S. Bergano; Carl R. Davidson

1996-01-01

356

A high gain array antenna with serially fed dipole elements  

Microsoft Academic Search

In this paper, a planar array antenna is proposed to maximize its gain performance, which is critical to point-to-point communications. Comparing to conventional parabolic reflectors, the planar array antenna is a cost effective alternative since the printed circuit board fabrication process can be adopted. However, the major drawback in the design of high gain array antenna is the losses in

Wen-Jiao Liao; Shen-Je You

2010-01-01

357

Concomitant DDX1 and MYCN gain in neuroblastoma.  

PubMed

DDX1, a gene mapping to the 2p24 region, has been observed to be co-amplified with MYCN in neuroblastoma. Co-amplification of the DDX1 gene is a consequence of the short physical distance between the two genes. Recently, it has been found that neuroblastoma cells can show a low increase in MYCN gene copy number, defined as MYCN gain. We studied 13 neuroblastomas with MYCN gain to evaluate the status of the DDX1 gene. We investigated DDX1/MYCN gain by double-colour FISH on interphase nuclei. All cases showed concomitant low extra copy number of DDX1 and MYCN. Heterogeneous distribution of nuclei displaying DDX1/MYCN gain was observed in almost all tumours, suggesting a clonal evolution of cells with DDX1/MYCN gain. This is the first report that shows DDX1 co-gained with MYCN in neuroblastoma and indicates that DDX1 over-representation is closely associated with an increase in MYCN copy number in neuroblastoma cells. Since DDX1 has already been found co-amplified with MYCN, DDX1 gain seems to be a further rearrangement due to the physical proximity of the two genes. Moreover, all patients with DDX1/MYCN gain show a good overall survival but a high frequency of adverse events. PMID:17611020

Defferrari, Raffaella; Tonini, Gian Paolo; Conte, Massimo; Papio, Filippo; Sementa, Angela Rita; Valent, Alexander; Schena, Francesca; Perri, Patrizia; Mazzocco, Katia

2007-10-18

358

Stimulated Rayleigh-Brillouin gain spectroscopy in pure gases  

NASA Technical Reports Server (NTRS)

Stimulated Rayleigh-Brillouin gain spectra of pure gases are reported. Stimulated Rayleigh scattering is now clearly distinguishable from stimulated Brillouin scattering without the aid of induced absorption. As examples, spectral line shapes of Ar and SF6 at various pressures and the associated gain asymmetry are discussed. Potential applications of coherent Rayleigh-Brillouin spectroscopy are suggested.

She, C. Y.; Herring, G. C.; Moosmuller, H.; Lee, S. A.

1983-01-01

359

Association between Reduced Sleep and Weight Gain in Women  

Microsoft Academic Search

Physiologic studies suggest that sleep restriction has metabolic effects that predispose to weight gain. The authors investigated the association between self-reported usual sleep duration and subsequent weight gain in the Nurses' Health Study. The 68,183 women who reported habitual sleep duration in 1986 were followed for 16 years. In analyses adjusted for age and body mass index, women sleeping 5

Sanjay R. Patel; Atul Malhotra; David P. White; Daniel J. Gottlieb; Frank B. Hu

2006-01-01

360

High gain and high peak power in planar waveguide lasers  

Microsoft Academic Search

We report enhanced peak power and gain for pulses in the 10-100 ?sec range, with specific peak power to 240 kW m-2 of electrode area at frequencies to 4 kHz. Pulsed small signal gain is increased by a factor of 7 relative to cw\\/long pulse excitation

F. J. Villarreal; Q. Cao; R. J. Ramirez; H. J. Baker; D. R. Hall

2001-01-01

361

A variable-gain output feedback control design methodology  

NASA Technical Reports Server (NTRS)

A digital control system design technique is developed in which the control system gain matrix varies with the plant operating point parameters. The design technique is obtained by formulating the problem as an optimal stochastic output feedback control law with variable gains. This approach provides a control theory framework within which the operating range of a control law can be significantly extended. Furthermore, the approach avoids the major shortcomings of the conventional gain-scheduling techniques. The optimal variable gain output feedback control problem is solved by embedding the Multi-Configuration Control (MCC) problem, previously solved at ICS. An algorithm to compute the optimal variable gain output feedback control gain matrices is developed. The algorithm is a modified version of the MCC algorithm improved so as to handle the large dimensionality which arises particularly in variable-gain control problems. The design methodology developed is applied to a reconfigurable aircraft control problem. A variable-gain output feedback control problem was formulated to design a flight control law for an AFTI F-16 aircraft which can automatically reconfigure its control strategy to accommodate failures in the horizontal tail control surface. Simulations of the closed-loop reconfigurable system show that the approach produces a control design which can accommodate such failures with relative ease. The technique can be applied to many other problems including sensor failure accommodation, mode switching control laws and super agility.

Halyo, Nesim; Moerder, Daniel D.; Broussard, John R.; Taylor, Deborah B.

1989-01-01

362

Cognitive and Achievement Gains for Kindergartners Instructed in Piagetian Operations.  

ERIC Educational Resources Information Center

Researchers taught unidimensional classification, unidimensional seriation, and number conversion to kindergartners lagging in cognitive development. The instruction resulted in significant gains on their achievement test scores. The gains seemed to result from mastery of key cognitive operations at a stage shift in cognitive development by…

Pasnak, Robert; And Others

1991-01-01

363

Amisulpride is an “atypical” antipsychotic associated with low weight gain  

Microsoft Academic Search

Rationale It is possible that amisulpride, with its unique receptor binding profile, is not associated with significant weight gain, a serious side effect of most “atypical” antipsychotic drugs. While most “atypicals” have a high affinity for both dopamine and serotonin receptors, amisulpride has only dopamine receptor action. Objectives To analyse the weight gain associated with amisulpride. Methods A pooled database

Stefan Leucht; Stefan Wagenpfeil; Johannes Hamann; Werner Kissling

2004-01-01

364

Consequences of Weight Gain Associated With Insulin Therapy in Adolescents  

Microsoft Academic Search

Intensive insulin therapy is associated with the delayed onset and reduced risk of the development of microvascular com- plications in type 1 diabetes and is therefore recommended for most patients, including children and adolescents. Intensification of insu- lin therapy can be accompanied by increased weight gain, and fear of weight gain can represent a major barrier to adherence to intensive

Francine Ratner Kaufman

2006-01-01

365

Gain stabilization of phototubes using a LED diode scheme  

NASA Astrophysics Data System (ADS)

The performance of LED diode gain stabilization schemes for RCA 4522 phototubes is evaluated. Under normal experimental conditions the use of a green Litronix GL56 LED and an ORTEC surface barrier detector provide the best results. An overall gain stabilization of ±0.5% over several months has been achieved.

Holm, L.; Fielding, H. W.; Neilson, G. C.

1985-02-01

366

Validity of Sudden Gains in Acute Phase Treatment of Depression  

ERIC Educational Resources Information Center

The authors examined the validity of sudden gains identified with T. Z. Tang and R. J. DeRubeis's (1999) method in 2 clinical data sets that involved treatment of major depressive disorder (N=227). Sudden gains replicated among self- and clinician reports of depressive symptoms and predicted better psychosocial functioning at the acute phase…

Vittengl, Jeffrey R.; Clark, Lee Anna; Jarrett, Robin B.

2005-01-01

367

High gain multigap avalanche detectors for Cerenkov ring imaging  

Microsoft Academic Search

We report on a continuing study of multigap parallel plate avalanche chambers, primarily as photoelectron detectors for use with Cerenkov ring imaging counters. By suitable control of the fields in successive gaps and by introducing screens to reduce photon feedback to the cathode the gain many be increased considerably. We have obtained gains in excess of 6 x 10 for

R. S. Gilmore; W. M. Lavender; D. W. G. S. Leith; S. H. Williams

1980-01-01

368

Gain and recombination dynamics of quantum-dot infrared photodetectors  

Microsoft Academic Search

The high photoconductive gain observed in semiconductor quantum dot infrared detectors (QDIPs) constitutes one of the most exciting recent topics in nanotechnology. In this paper we present a theory of diffusion and recombination in QDIPs which is an attempt to explain the recently reported values of gain in these devices. We allow the kinetics to encompass both the diffusion and

H. Lim; B. Movaghar; S. Tsao; M. Taguchi; W. Zhang; A. A. Quivy; M. Razeghi

2006-01-01

369

Effects of Elevated Temperature on Carcinogenesis.  

National Technical Information Service (NTIS)

To study the effects of elevated temperatures on carcinogenesis, 7 to 9 week old C3H-mice maintained at either 23 or 30 degrees-C were divided into four groups: a no treatment control; high level carcinogen, 2.0 milligrams/week (mg/wk) benzo(a)pyrene (503...

H. S. Weiss K. M. Kerr

1975-01-01

370

[Elevation of hepatic enzyme values in hyperthyroidism].  

PubMed

Serum or plasma alanine aminotransferase (ALAT) activity may sometimes exhibit even considerable increases in connection with hyperthyroidism and present a diagnostic as well as a therapeutic problem. Open questions include whether the hepatic change is related to a primary disease, and how to select treatment. We report two patients, in whom carbimazole medication initiated for Graves' disease normalized elevated ALAT values. PMID:21553506

Soppi, Esa; Paul, Robert

2011-01-01

371

76 FR 72661 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...above State City/town/county Source of flooding Location ** ground [caret] Elevation...in feet (NAVD) Depth in feet above Flooding source(s) Location of referenced ground...1.2 miles +1038 +1036 upstream of Steam Hollow Road. Dundaff...

2011-11-25

372

Management of ST-elevation myocardial infarction  

Microsoft Academic Search

Ischaemic heart disease, and myocardial infarction (MI) in particular, remains a common cause of morbidity and mortality worldwide. Acute ST-elevation MI (STEMI) usually results from occlusive thrombus formation following coronary plaque rupture. Immediate measures, such as the administration of aspirin and early defibrillation, can be lifesaving in STEMI. Prompt and appropriate reperfusion therapy plays a major role in improving short-term

Rhidian J. Shelton; Daniel J. Blackman

2010-01-01

373

Elevation correction factor for absolute pressure measurements  

NASA Technical Reports Server (NTRS)

With the arrival of highly accurate multi-port pressure measurement systems, conditions that previously did not affect overall system accuracy must now be scrutinized closely. Errors caused by elevation differences between pressure sensing elements and model pressure taps can be quantified and corrected. With multi-port pressure measurement systems, the sensing elements are connected to pressure taps that may be many feet away. The measurement system may be at a different elevation than the pressure taps due to laboratory space or test article constraints. This difference produces a pressure gradient that is inversely proportional to height within the interface tube. The pressure at the bottom of the tube will be higher than the pressure at the top due to the weight of the tube's column of air. Tubes with higher pressures will exhibit larger absolute errors due to the higher air density. The above effect is well documented but has generally been taken into account with large elevations only. With error analysis techniques, the loss in accuracy from elevation can be easily quantified. Correction factors can be applied to maintain the high accuracies of new pressure measurement systems.

Panek, Joseph W.; Sorrells, Mark R.

1996-01-01

374

Climatic Change at High Elevation Sites.  

National Technical Information Service (NTIS)

A Workshop on climatic change at high elevation sites was held September 11-15, 1995 in Wengen, Switzerland. The meeting was sponsored by both U.S. (Department of Energy, National Science Foundation and National Oceanic & Atmospheric Administration) and E...

H. F. Diaz

2002-01-01

375

Elevation correction and the geoid tutorial  

NSDL National Science Digital Library

The Earth is not a perfect sphere, but is instead more like a slightly squashed sphere called an ellipsoid. Because of this, GPS receivers must use a correction model (called a geoid) to calculate true elevation above sea level. UNAVCO has prepared this explanation for both teachers and students to learn more about accuracy, scientific models, and how GPS receivers work.

Unavco

376

Dynamic multibody modeling for tethered space elevators  

Microsoft Academic Search

This paper presents a fundamental modeling strategy for dealing with powered and propelled bodies moving along space tethers. The tether is divided into a large number of discrete masses, which are connected by viscoelastic springs. The tether is subject to the full range of forces expected in Earth orbit in a relatively simple manner. Two different models of the elevator

Paul Williams

2009-01-01

377

Lunar transportation scenarios utilising the Space Elevator  

Microsoft Academic Search

The Space Elevator (SE) concept has begun to receive an increasing amount of attention within the space community over the past couple of years and is no longer widely dismissed as pure science fiction. In light of the renewed interest in a, possibly sustained, human presence on the Moon and the fact that transportation and logistics form the bottleneck of

Kilian A. Engel

2005-01-01

378

The physics of the space elevator  

Microsoft Academic Search

A space elevator is a tall tower rising from a point on the Earth's equator to a height well above a geostationary orbit, where it terminates in a counterweight. Although the concept is more than a century old, it was only with the discovery of carbon nanotubes that it began to receive serious scientific attention. NASA commissioned a study of

P. K. Aravind

2007-01-01

379

75 FR 3171 - Final Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...Depth in feet above ground. [caret]Elevation in meters (MSL). ADDRESSES City of Afton Maps are available for inspection at 3033 St. Croix Trail South, Afton, MN 55001. City of Bayport Maps are available for inspection at 294 North 3rd Street,...

2010-01-20

380

Satellite Placement Using a Partial Space Elevator  

NASA Astrophysics Data System (ADS)

The space elevator has been proposed as an alternate method for launching cargo into space. However, the construction of such a structure requires a material much stronger than any currently in existence. Instead, a partial elevator is considered for satellite placement. In the first part of the thesis, the fundamentals of very long tethered systems are studied. From static analysis on a simple two-body system, it is demonstrated that an assumption made in the conventional analysis does not apply to very long tethered systems. For a uniform tether, the axial stress distribution is obtained. Following the Lagrangian approach, the equations of motion governing the planar librations of a multi-body tethered system are derived. From a linearization of these equations, the libration frequencies are found. Then, by solving the nonlinear equations numerically, the responses to various changes in the system parameters are determined. In the second part of the thesis, the use of a partial elevator in satellite placement is studied. In the case of single climber transit, residual librations occur, which alter the shape and size of the orbit of a satellite launched from the climber. An approach using two climbers is investigated in order to decrease the residual libration and thereby reduce orbit placement errors. Also, some energy calculations are done to determine whether the partial elevator offers significant advantages.

Woo, Pamela

381

Tethered space elevator Possible applications & demonstrative experiments  

NASA Astrophysics Data System (ADS)

The scenario for the next decades of human activities in space is characterized by the Space Station. Besides the manned core station, several facilities are already being studied with the purpose of expanding the capabilities of the Space Station itself. The use of tethers on the core station is an intriguing possibility which is receiving increased attention. Among the various uses considered for tethers, particular attention has been paid to a Tethered Space Elevator System. Interest in such a facility, able to move between the ends of a deployed tether, depends on the broad range of new capabilities opened by this element. In particular, the Elevator utilization as a mobile microgravity laboratory presents unique possibilities for a new variable microgravity environment. This paper reviews Aeritalia studies of the Tethered Space Elevator. A survey of possible applications is presented; system topics are discussed; and a description is provided of the key elements and related technologies of the Elevator system. Finally, a presentation is given of the planned activities leading to the demonstration of the key features of this new space system.

Bevilacqua, F.; Merlina, P.; Ciardo, S.

382

ELEVATION DATA FOR OREGON AND WASHINGTON  

EPA Science Inventory

The WA 1:24,000 scale data have an elevation at approx. every 30 meters. The 1:250,000 scale data are gathered at intervals of approx. every 85 meters along the ground. These data may be used in the generation of graphics such as isometric projections displaying slope, directio...

383

ELEVATING FRC MATERIAL DUCTILITY TO INFRASTRUCTURE DURABILITY  

Microsoft Academic Search

Concrete is a brittle material. The lack of durability of concrete infrastructure has been a recognized concern. Research in fiber reinforced concrete (FRC) often addresses the issue of material brittleness. However, the translation of improved ductility of FRC into infrastructure durability is often overlooked. This paper explores the concept of elevating the ductility of high performance fiber reinforced concretes (HPFRCC)

Victor C. Li; Henrik Stang

2004-01-01

384

76 FR 14359 - Proposed Flood Elevation Determinations  

Federal Register 2010, 2011, 2012, 2013

...Elevation (BFE) location descriptions for Pollard Creek Tributary No. 5 in Palo Pinto County...pertaining to the location descriptions for the Pollard Creek Tributary No. 5 BFEs are to be...Areas'' addressed the flooding source Pollard Creek Tributary No. 5. The...

2011-03-16

385

Physiology of Respiration of High Elevations.  

National Technical Information Service (NTIS)

A hypoxic isocapnic test was used to study 40 sea level (SL) subjects. The data suggest that a high elevation environment produces a sensitization of the peripheral chemorreceptors in SL subjects. The lower the response at SL the higher the response at HA...

J. C. Cruz-Jibaja

1970-01-01

386

Advanced composite elevator for Boeing 727 aircraft  

NASA Technical Reports Server (NTRS)

Detail design activities are reported for a program to develop an advanced composites elevator for the Boeing 727 commercial transport. Design activities include discussion and results of the ancillary test programs, sustaining efforts, weight status, manufacturing producibility studies, quality assurance development, and production status.

1978-01-01

387

Performance of metakaolin concrete at elevated temperatures  

Microsoft Academic Search

An experimental investigation was conducted to evaluate the performance of metakaolin (MK) concrete at elevated temperatures up to 800 °C. Eight normal and high strength concrete (HSC) mixes incorporating 0%, 5%, 10% and 20% MK were prepared. The residual compressive strength, chloride-ion penetration, porosity and average pore sizes were measured and compared with silica fume (SF), fly ash (FA) and

Chi-Sun Poon; Salman Azhar; Mike Anson; Yuk-Lung Wong

2003-01-01

388

Some measurements of height gain at V.H.P.  

NASA Astrophysics Data System (ADS)

Some of the published work on antenna height gain is reviewed and limitations of the currently available information are highlighted. Comparison is then made with the results of height gain experiments undertaken in southeastern England at frequencies of approximately 95 MHz and 200 MHz. The variation of height gain is investigated, as is a relationship between height gain and the location variability of received field strength within a given environmental area. It was suggested that within the range investigated (experiments done at 95 MHz used vertical polarization and path lengths varying from about 25 km to 105 km) height gain may be represented as n dB for each doubling of antenna height. The value of n varies with the local environment at the receiving site.

Fairbrother, John; Hughes, Kevin A.; Holden, Douglas M.

1987-11-01

389

Gain curves and hydrodynamic modeling for shock ignition  

SciTech Connect

Ignition of a precompressed thermonuclear fuel by means of a converging shock is now considered as a credible scheme to obtain high gains for inertial fusion energy. This work aims at modeling the successive stages of the fuel time history, from compression to final thermonuclear combustion, in order to provide the gain curves of shock ignition (SI). The leading physical mechanism at work in SI is pressure amplification, at first by spherical convergence, and by collision with the shock reflected at center during the stagnation process. These two effects are analyzed, and ignition conditions are provided as functions of the shock pressure and implosion velocity. Ignition conditions are obtained from a non-isobaric fuel assembly, for which we present a gain model. The corresponding gain curves exhibit a significantly lower ignition threshold and higher target gains than conventional central ignition.

Lafon, M.; Ribeyre, X.; Schurtz, G. [Centre Lasers Intenses et Applications, Universite Bordeaux 1-CNRS-CEA, 351 Cours de la Liberation, Talence 33405 (France)

2010-05-15

390

Relationship Between Optimal Gain and Coherence Zone in Flight Simulation  

NASA Technical Reports Server (NTRS)

In motion simulation the inertial information generated by the motion platform is most of the times different from the visual information in the simulator displays. This occurs due to the physical limits of the motion platform. However, for small motions that are within the physical limits of the motion platform, one-to-one motion, i.e. visual information equal to inertial information, is possible. It has been shown in previous studies that one-to-one motion is often judged as too strong, causing researchers to lower the inertial amplitude. When trying to measure the optimal inertial gain for a visual amplitude, we found a zone of optimal gains instead of a single value. Such result seems related with the coherence zones that have been measured in flight simulation studies. However, the optimal gain results were never directly related with the coherence zones. In this study we investigated whether the optimal gain measurements are the same as the coherence zone measurements. We also try to infer if the results obtained from the two measurements can be used to differentiate between simulators with different configurations. An experiment was conducted at the NASA Langley Research Center which used both the Cockpit Motion Facility and the Visual Motion Simulator. The results show that the inertial gains obtained with the optimal gain are different than the ones obtained with the coherence zone measurements. The optimal gain is within the coherence zone.The point of mean optimal gain was lower and further away from the one-to-one line than the point of mean coherence. The zone width obtained for the coherence zone measurements was dependent on the visual amplitude and frequency. For the optimal gain, the zone width remained constant when the visual amplitude and frequency were varied. We found no effect of the simulator configuration in both the coherence zone and optimal gain measurements.

Gracio, Bruno Jorge Correia; Pais, Ana Rita Valente; vanPaassen, M. M.; Mulder, Max; Kely, Lon C.; Houck, Jacob A.

2011-01-01

391

Reducing elevator energy use: A comparison of posted feedback and reduced elevator convenience  

PubMed Central

The effects of two different procedures for reducing elevator energy use were assessed using a multiple-baseline design. In the first procedure, feedback about the amount of energy consumed by the elevators each week was posted on each elevator door. Later, signs advocating the use of stairs to save energy and improve health were posted next to the feedback signs. In the second procedure, the time required to travel between floors was increased by adding a delay to the elevator door closing mechanisms. Results indicated that neither feedback alone nor feedback plus educational signs reduced the amount of energy consumed by the elevators. However, use of the door delay reduced consumption by one-third in all elevators. A second experiment replicated the effect of the door delay on energy consumption and, in addition, demonstrated that the door delay also produced a reduction in the number of persons using the elevator. The second experiment also showed that, following an initial period during which a full delay was in effect, a gradual reduction of the delay interval resulted in continued energy conservation. Reduced convenience as a general strategy for energy conservation is discussed.

Houten, Ron Van; Nau, Paul A.; Merrigan, Michael

1981-01-01

392

West and south elevations, view to northeast. Proximity of house ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

West and south elevations, view to northeast. Proximity of house and trees precluded photography of north and east elevations, but building is symmetrical. Entry is in east elevation; windmill was mounted at third story level on north elevation. - Drew-Sherwood Farm, Tank House, 7927 Elk Grove Boulevard, Elk Grove, Sacramento County, CA

393

Procedures and Use of Time in Reading Classes in High-Gain and Low-Gain Elementary Schools in Chicago.  

ERIC Educational Resources Information Center

A study of 39 elementary schools in Chicago was conducted to compare two sets of schools, those whose students made above average yearly gains in reading comprehension and those whose students' reading gains were below average. These schools were compared on the proportion of time spent on task, on what the teacher and pupils did during reading…

Fredrick, Wayne; And Others

394

A weight-gain-for-gestational-age z score chart for the assessment of maternal weight gain in pregnancy123  

PubMed Central

Background: To establish the unbiased relation between maternal weight gain in pregnancy and perinatal health, a classification for maternal weight gain is needed that is uncorrelated with gestational age. Objective: The goal of this study was to create a weight-gain-for-gestational-age percentile and z score chart to describe the mean, SD, and selected percentiles of maternal weight gain throughout pregnancy in a contemporary cohort of US women. Design: The study population was drawn from normal-weight women with uncomplicated, singleton pregnancies who delivered at the Magee-Womens Hospital in Pittsburgh, PA, 1998–2008. Analyses were based on a randomly selected subset of 648 women for whom serial prenatal weight measurements were available through medical chart record abstraction (6727 weight measurements). Results: The pattern of maternal weight gain throughout gestation was estimated by using a random-effects regression model. The estimates were used to create a chart with the smoothed means, percentiles, and SDs of gestational weight gain for each week of pregnancy. Conclusion: This chart allows researchers to express total weight gain as an age-standardized z score, which can be used in epidemiologic analyses to study the association between pregnancy weight gain and adverse or physiologic pregnancy outcomes independent of gestational age.

Platt, Robert W; Abrams, Barbara; Himes, Katherine P; Simhan, Hyagriv N; Bodnar, Lisa M

2013-01-01

395

Elevated expression of activins promotes muscle wasting and cachexia.  

PubMed

In models of cancer cachexia, inhibiting type IIB activin receptors (ActRIIBs) reverse muscle wasting and prolongs survival, even with continued tumor growth. ActRIIB mediates signaling of numerous TGF-? proteins; of these, we demonstrate that activins are the most potent negative regulators of muscle mass. To determine whether activin signaling in the absence of tumor-derived factors induces cachexia, we used recombinant serotype 6 adeno-associated virus (rAAV6) vectors to increase circulating activin A levels in C57BL/6 mice. While mice injected with control vector gained ~10% of their starting body mass (3.8±0.4 g) over 10 wk, mice injected with increasing doses of rAAV6:activin A exhibited weight loss in a dose-dependent manner, to a maximum of -12.4% (-4.2±1.1 g). These reductions in body mass in rAAV6:activin-injected mice correlated inversely with elevated serum activin A levels (7- to 24-fold). Mechanistically, we show that activin A reduces muscle mass and function by stimulating the ActRIIB pathway, leading to deleterious consequences, including increased transcription of atrophy-related ubiquitin ligases, decreased Akt/mTOR-mediated protein synthesis, and a profibrotic response. Critically, we demonstrate that the muscle wasting and fibrosis that ensues in response to excessive activin levels is fully reversible. These findings highlight the therapeutic potential of targeting activins in cachexia. PMID:24378873

Chen, Justin L; Walton, Kelly L; Winbanks, Catherine E; Murphy, Kate T; Thomson, Rachel E; Makanji, Yogeshwar; Qian, Hongwei; Lynch, Gordon S; Harrison, Craig A; Gregorevic, Paul

2014-04-01

396

Effect of intermittent kangaroo mother care on weight gain of low birth weight neonates with delayed weight gain.  

PubMed

Objective: To evaluate intermittent Kangaroo Mother Care (KMC) with additional opportunities to breastfeed on weight gain of low birth weight (LBW) neonates with delayed weight gain. Methods: 40 LBW neonates were followed to see whether KMC with additional opportunities to breastfeed improved weight gain. Results: In the KMC group, the mean age of regaining birth weight was significantly less (15.68 vs. 24.56 days) and the average daily weight gain was significantly higher (22.09 vs. 10.39 g, p < .001) than controls. Conclusion: KMC with additional opportunities to breastfeed was found to be an effective intervention for LBWs with delayed weight gain and should be considered to be an effective strategy. PMID:24868132

Samra, Nashwa M; Taweel, Amal El; Cadwell, Karin

2013-01-01

397

Gain Scheduling for the Orion Launch Abort Vehicle Controller  

NASA Technical Reports Server (NTRS)

One of NASAs challenges for the Orion vehicle is the control system design for the Launch Abort Vehicle (LAV), which is required to abort safely at any time during the atmospheric ascent portion of ight. The focus of this paper is the gain design and scheduling process for a controller that covers the wide range of vehicle configurations and flight conditions experienced during the full envelope of potential abort trajectories from the pad to exo-atmospheric flight. Several factors are taken into account in the automation process for tuning the gains including the abort effectors, the environmental changes and the autopilot modes. Gain scheduling is accomplished using a linear quadratic regulator (LQR) approach for the decoupled, simplified linear model throughout the operational envelope in time, altitude and Mach number. The derived gains are then implemented into the full linear model for controller requirement validation. Finally, the gains are tested and evaluated in a non-linear simulation using the vehicles ight software to ensure performance requirements are met. An overview of the LAV controller design and a description of the linear plant models are presented. Examples of the most significant challenges with the automation of the gain tuning process are then discussed. In conclusion, the paper will consider the lessons learned through out the process, especially in regards to automation, and examine the usefulness of the gain scheduling tool and process developed as applicable to non-Orion vehicles.

McNamara, Sara J.; Restrepo, Carolina I.; Madsen, Jennifer M.; Medina, Edgar A.; Proud, Ryan W.; Whitley, Ryan J.

2011-01-01

398

Addressing women's concerns about weight gain due to smoking cessation.  

PubMed

Specific concerns about weight gain following smoking cessation inhibit attempts to quit smoking, especially in women. However, adjunct interventions to prevent weight gain after cessation have generally been successful only in attenuating, rather than preventing, weight gain. More aggressive weight control adjuncts may be necessary to prevent cessation-induced weight gain. On the other hand, weight control programs have not been found to improve long-term smoking abstinence and, in fact, may actually impede abstinence, necessitating a search for alternative approaches to addressing weight concerns. Since the typical amount of weight gain is essentially trivial from a health standpoint, particularly when compared with the health benefits of quitting smoking, the most appropriate clinical strategy may be to combat the weight concerns themselves rather than the weight gain. A second alternative approach is to focus all treatment efforts on smoking cessation alone, to avoid placing excessive burdens on participants resulting from attempting simultaneous changes in multiple health behaviors (i.e., smoking and those related to weight). The rationales for these three clinical approaches to addressing concerns about weight gain-more effective weight control, direct reduction in weight concerns by cognitive-behavioral treatment, and smoking cessation only-are presented, followed by descriptions of the adjunct treatments based on these approaches currently being evaluated in a clinical outcome study with women trying to quit smoking. PMID:9258862

Perkins, K A; Levine, M D; Marcus, M D; Shiffman, S

1997-01-01

399

Caribbean mangroves adjust to rising sea level through biotic controls on change in soil elevation  

USGS Publications Warehouse

Aim The long-term stability of coastal ecosystems such as mangroves and salt marshes depends upon the maintenance of soil elevations within the intertidal habitat as sea level changes. We examined the rates and processes of peat formation by mangroves of the Caribbean Region to better understand biological controls on habitat stability. Location Mangrove-dominated islands on the Caribbean coasts of Belize, Honduras and Panama were selected as study sites. Methods Biological processes controlling mangrove peat formation were manipulated (in Belize) by the addition of nutrients (nitrogen or phosphorus) to Rhizophora mangle (red mangrove), and the effects on the dynamics of soil elevation were determined over a 3-year period using rod surface elevation tables (RSET) and marker horizons. Peat composition and geological accretion rates were determined at all sites using radiocarbon-dated cores. Results The addition of nutrients to mangroves caused significant changes in rates of mangrove root accumulation, which influenced both the rate and direction of change in elevation. Areas with low root input lost elevation and those with high rates gained elevation. These findings were consistent with peat analyses at multiple Caribbean sites showing that deposits (up to 10 m in depth) were composed primarily of mangrove root matter. Comparison of radiocarbon-dated cores at the study sites with a sea-level curve for the western Atlantic indicated a tight coupling between peat building in Caribbean mangroves and sea-level rise over the Holocene. Main conclusions Mangroves common to the Caribbean region have adjusted to changing sea level mainly through subsurface accumulation of refractory mangrove roots. Without root and other organic inputs, submergence of these tidal forests is inevitable due to peat decomposition, physical compaction and eustatic sea-level rise. These findings have relevance for predicting the effects of sea-level rise and biophysical processes on tropical mangrove ecosystems.

McKee, K.L.; Cahoon, D.R.; Feller, I.C.

2007-01-01

400

20 CFR 404.1572 - What we mean by substantial gainful activity.  

Code of Federal Regulations, 2013 CFR

... What we mean by substantial gainful activity. 404.1572 Section 404.1572...Disability and Blindness Substantial Gainful Activity § 404.1572 What we mean by substantial gainful activity. Substantial gainful activity is...

2013-04-01

401

20 CFR 416.972 - What we mean by substantial gainful activity.  

Code of Federal Regulations, 2013 CFR

... What we mean by substantial gainful activity. 416.972 Section 416.972 ...Disability and Blindness Substantial Gainful Activity § 416.972 What we mean by substantial gainful activity. Substantial gainful activity is...

2013-04-01

402

The effect of wiggler errors on FEL gain  

SciTech Connect

For an FEL operating in the exponential regime before saturation, we present an analytic description of the effect on the gain of longitudinal velocity variations arising from wiggler field errors. The average gain reduction and the width of the output power distribution are expressed in terms of the mean square average of the ponderomotive phase shift per gain length. A scheme for correcting the electron trajectory using position monitors and dipole correctors is analyzed. Our work is directly applicable to the design of FEL amplifiers and the results are encouraging for their feasibility. 13 refs., 3 figs.

Yu, L.H.; Krinsky, S. (Brookhaven National Lab., Upton, NY (United States)); Gluckstern, R.L.; van Zeijts, J.B.J. (Maryland Univ., College Park, MD (United States). Dept. of Physics)

1991-01-01

403

Gain saturation in semiconductor lasers - Theory and experiment  

NASA Technical Reports Server (NTRS)

The semiconductor stimulated gain saturation model of Zee has been extended using reasonable approximations to obtain an analytical solution for the gain saturation process in PbSnTe and to determine the limit to single mode power directly from the gain expression, the intraband relaxation time, and device and material parameters. The theoretical results are compared with experimental observations for single transverse mode cavity narrow stripe buried heterostructure PbSnTe lasers. Those results are interpreted in terms of an intraband relaxation time on the order of 2 x 10 to the -12th s in the temperature range 20-80 K.

Kasemset, D.; Fonstad, C. G., Jr.

1982-01-01

404

Concept for an off-line gain stabilisation method.  

PubMed

Conceptual ideas are presented for an off-line gain stabilisation method for spectrometry, in particular for alpha-particle spectrometry at low count rate. The method involves list mode storage of individual energy and time stamp data pairs. The 'Stieltjes integral' of measured spectra with respect to a reference spectrum is proposed as an indicator for gain instability. 'Exponentially moving averages' of the latter show the gain shift as a function of time. With this information, the data are relocated stochastically on a point-by-point basis. PMID:14987634

Pommé, S; Sibbens, G

2004-01-01

405

Achieving improved cycle efficiency via pressure gain combustors  

SciTech Connect

As part of the Department of Energy`s Advanced Gas Turbine Systems Program, an investigation is being performed to evaluate ``pressure gain`` combustion systems for gas turbine applications. This paper presents experimental pressure gain and pollutant emission data from such combustion systems. Numerical predictions for certain combustor geometries are also presented. It is reported that for suitable aerovalved pulse combustor geometries studied experimentally, an overall combustor pressure gain of nearly 1 percent can be achieved. It is also shown that for one combustion system operating under typical gas turbine conditions, NO{sub x} and CO emmissions, are about 30 ppmv and 8 ppmv, respectively.

Gemmen, R.S.; Janus, M.C.; Richards, G.A.; Norton, T.S. [USDOE Morgantown Energy Technology Center, WV (United States); Rogers, W.A. [EG& G Technical Services of West Virginia, Morgantown, WV (United States)

1995-04-01

406

Proton and gamma ray induced gain degradation in bipolar transistor  

NASA Astrophysics Data System (ADS)

This paper describes the results of the effect of 24 MeV proton and (CO)-C-60 gamma-irradiation on the collector characteristic., and forward current gain of commercial bipolar transistor (npn 2N2219A). The transistor has been exposed to these radiations in the biased condition and the collector characteristics and forward current gain have been measured as a function of proton fluence and gamma-dose. The observation is that both the proton and gamma-irradiation induce significant gain degradation in the transistor. The results are discussed in terms of displacement damage produced by energetic protons and gamma-radiation in the bulk of the semiconductor.

Kulkarni, S. R.; Sarma, A.; Joshi, G. R.; Ravindra, M.; Damle, R.

2003-09-01

407

Fresnel reflection from a cavity with net roundtrip gain  

NASA Astrophysics Data System (ADS)

A planewave incident on an active etalon with net roundtrip gain may be expected to diverge in field amplitude, yet applying the Fresnel formalism to Maxwell's equations admits a convergent solution. We describe this solution mathematically and provide additional insight by demonstrating the response of such a cavity to an incident beam of light. Cavities with net roundtrip gain have often been overlooked in the literature, and a clear understanding of their behavior yields insight to negative refraction in nonmagnetic media, a duality between loss and gain, amplified total internal reflection, and the negative-index lens.

Mansuripur, Tobias S.; Mansuripur, Masud

2014-03-01

408

Superluminal propagation via coherent manipulation of the Raman gain process  

SciTech Connect

We present a method of manipulating the Raman process by using a coherent control field which leads to splitting of the Raman gain peak into a doublet and anomalous dispersion in the region between the gain peaks. We show how the region of almost no Raman gain and strong anomalous dispersion is ideally suited for producing superluminal propagation. In particular, we show that the group index for a {sup 23}Na condensate could be in the range -10{sup 3} to -10{sup 4}.

Agarwal, G.S.; Dasgupta, Shubhrangshu [Physical Research Laboratory, Navrangpura, Ahmedabad 380 009 (India)

2004-08-01

409

LPV Controller Interpolation for Improved Gain-Scheduling Control Performance  

NASA Technical Reports Server (NTRS)

In this paper, a new gain-scheduling control design approach is proposed by combining LPV (linear parameter-varying) control theory with interpolation techniques. The improvement of gain-scheduled controllers can be achieved from local synthesis of Lyapunov functions and continuous construction of a global Lyapunov function by interpolation. It has been shown that this combined LPV control design scheme is capable of improving closed-loop performance derived from local performance improvement. The gain of the LPV controller will also change continuously across parameter space. The advantages of the newly proposed LPV control is demonstrated through a detailed AMB controller design example.

Wu, Fen; Kim, SungWan

2002-01-01

410

Recovery of elevation from estimated gradient fields constrained by digital elevation maps of lower lateral resolution  

NASA Astrophysics Data System (ADS)

Depth measurement techniques like stereo analysis and laser range scanning often yield a lateral resolution below image resolution. In contrast, shading-based methods estimate the elevation model at image resolution. We present a computationally efficient approach to recover a surface of high vertical and high lateral resolution from a noisy gradient field and independently measured elevation data of lower lateral resolution, relying on a minimization of the mean squared difference between the low-pass component of the surface obtained based on shading information and that of the independently measured elevation data. The presented method is compared to a reference approach that minimizes a weighted sum comprised of the mean squared difference between the low-pass components of the estimated gradient field and the optimized model, respectively. The presented algorithm is applied using lunar orbital image data and stereo elevation data and is evaluated regarding orbital laser altimeter measurements of high vertical accuracy.

Grumpe, Arne; Wöhler, Christian

2014-08-01

411

Sensitivity of the South Asian monsoon to elevated and non-elevated heating  

PubMed Central

Elevated heating by the Tibetan Plateau was long thought to drive the South Asian summer monsoon, but recent work showed this monsoon was largely unaffected by removal of the plateau in a climate model, provided the narrow orography of adjacent mountain ranges was preserved. There is debate about whether those mountain ranges generate a strong monsoon by insulating the thermal maximum from cold and dry extratropical air or by providing a source of elevated heating. Here we show that the strength of the monsoon in a climate model is more sensitive to changes in surface heat fluxes from non-elevated parts of India than it is to changes in heat fluxes from adjacent elevated terrain. This result is consistent with the hypothesis that orography creates a strong monsoon by serving as a thermal insulator, and suggests that monsoons respond most strongly to heat sources coincident with the thermal maximum.

Boos, William R.; Kuang, Zhiming

2013-01-01

412

Elevational dependence of projected hydrologic changes in the San Francisco Estuary and watershed  

USGS Publications Warehouse

California's primary hydrologic system, the San Francisco Estuary and its upstream watershed, is vulnerable to the regional hydrologic consequences of projected global climate change. Previous work has shown that a projected warming would result in a reduction of snowpack storage leading to higher winter and lower spring-summer streamflows and increased spring-summer salinities in the estuary. The present work shows that these hydrologic changes exhibit a strong dependence on elevation, with the greatest loss of snowpack volume in the 1300-2700 m elevation range. Exploiting hydrologic and estuarine modeling capabilities to trace water as it moves through the system reveals that the shift of water in mid-elevations of the Sacramento river basin from snowmelt to rainfall runoff is the dominant cause of projected changes in estuarine inflows and salinity. Additionally, although spring-summer losses of estuarine inflows are balanced by winter gains, the losses have a stronger influence on salinity since longer spring-summer residence times allow the inflow changes to accumulate in the estuary. The changes in inflows sourced in the Sacramento River basin in approximately the 1300-2200 m elevation range thereby lead to a net increase in estuarine salinity under the projected warming. Such changes would impact ecosystems throughout the watershed and threaten to contaminate much of California's freshwater supply.

Knowles, N.; Cayan, D. R.

2004-01-01

413

Schneiderian membrane perforation rate during sinus elevation using piezosurgery: clinical results of 100 consecutive cases.  

PubMed

The lateral window sinus elevation procedure has become a routine and highly successful preprosthetic procedure that is used to increase bone volume in the posterior maxilla for the placement of dental implants. Many surgical techniques have been proposed that provide access to the maxillary sinus through the lateral wall to allow for elevation of the sinus membrane. Among these are the multiple variations of the hinge and complete osteotomy techniques, which make use of rotary cutting instruments for the antrostomy. The most common intraoperative complication with these surgical approaches is perforation of the schneiderian membrane, with perforation rates of 14% to 56% reported in the literature. In most instances, perforation occurs either while using rotary instruments to make the window or when using hand instruments to gain initial access to begin the elevation of the membrane from the sinus walls. This article presents an alternative approach that uses a piezoelectric instrument for the sinus elevation procedure. Although new to the United States, this approach has been used successfully in Europe for many years. The membrane perforation rate in this series of 100 consecutive cases using the piezoelectric technique has been reduced from the average reported rate of 30% with rotary instrumentation to 7%. Furthermore, all perforations with the piezoelectric technique occurred during the hand instrumentation phase and not with the piezoelectric inserts. PMID:17990437

Wallace, Stephen S; Mazor, Ziv; Froum, Stuart J; Cho, Sang-Choon; Tarnow, Dennis P

2007-10-01

414

Plasma viscosity elevations with simulated weightlessness  

NASA Technical Reports Server (NTRS)

A hypothesis correlating an increase in blood viscosity during bed rest to a decrease in aerobic capacity during simulated weightlessness is tested. Eight human subjects were studied on the sixth day of bed rest during two consecutive 10-d bed rest periods separated by a 14-d recovery interval designed to simulate the flight-layover schedule of Shuttle astronauts. Plasma viscosity and volume were measured, together with maximal aerobic capacity (VO2max). An increase in hematocrit, plasma protein, and fibrinogen concentrations was found, contributing to an elevation in plasma viscosity. VO2max decreased significantly in the first, but not the second bed rest cycle, and though many individuals exhibited a decrease in plasma volume and aerobic capacity coupled with elevated plasma viscosity, correlations between these variables were lacking. It is concluded that the decrease in VO2max observed following simulated weightlessness cannot be attributed to alterations in muscle blood flow resulting from increased blood viscosity.

Martin, D. G.; Convertino, V. A.; Goldwater, D.; Ferguson, E. W.; Schoomaker, E. B.

1986-01-01

415

Plastic responses to elevated temperature in low and high elevation populations of three grassland species.  

PubMed

Local persistence of plant species in the face of climate change is largely mediated by genetic adaptation and phenotypic plasticity. In species with a wide altitudinal range, population responses to global warming are likely to differ at contrasting elevations. In controlled climate chambers, we investigated the responses of low and high elevation populations (1200 and 1800 m a.s.l.) of three nutrient-poor grassland species, Trifolium montanum, Ranunculus bulbosus, and Briza media, to ambient and elevated temperature. We measured growth-related, reproductive and phenological traits, evaluated differences in trait plasticity and examined whether trait values or plasticities were positively related to approximate fitness and thus under selection. Elevated temperature induced plastic responses in several growth-related traits of all three species. Although flowering phenology was advanced in T. montanum and R. bulbosus, number of flowers and reproductive allocation were not increased under elevated temperature. Plasticity differed between low and high elevation populations only in leaf traits of T. montanum and B. media. Some growth-related and phenological traits were under selection. Moreover, plasticities were not correlated with approximate fitness indicating selectively neutral plastic responses to elevated temperature. The observed plasticity in growth-related and phenological traits, albeit variable among species, suggests that plasticity is an important mechanism in mediating plant responses to elevated temperature. However, the capacity of species to respond to climate change through phenotypic plasticity is limited suggesting that the species additionally need evolutionary adaptation to adjust to climate change. The observed selection on several growth-related and phenological traits indicates that the study species have the potential for future evolution in the context of a warming climate. PMID:24901500

Frei, Esther R; Ghazoul, Jaboury; Pluess, Andrea R

2014-01-01

416

Plastic Responses to Elevated Temperature in Low and High Elevation Populations of Three Grassland Species  

PubMed Central

Local persistence of plant species in the face of climate change is largely mediated by genetic adaptation and phenotypic plasticity. In species with a wide altitudinal range, population responses to global warming are likely to differ at contrasting elevations. In controlled climate chambers, we investigated the responses of low and high elevation populations (1200 and 1800 m a.s.l.) of three nutrient-poor grassland species, Trifolium montanum, Ranunculus bulbosus, and Briza media, to ambient and elevated temperature. We measured growth-related, reproductive and phenological traits, evaluated differences in trait plasticity and examined whether trait values or plasticities were positively related to approximate fitness and thus under selection. Elevated temperature induced plastic responses in several growth-related traits of all three species. Although flowering phenology was advanced in T. montanum and R. bulbosus, number of flowers and reproductive allocation were not increased under elevated temperature. Plasticity differed between low and high elevation populations only in leaf traits of T. montanum and B. media. Some growth-related and phenological traits were under selection. Moreover, plasticities were not correlated with approximate fitness indicating selectively neutral plastic responses to elevated temperature. The observed plasticity in growth-related and phenological traits, albeit variable among species, suggests that plasticity is an important mechanism in mediating plant responses to elevated temperature. However, the capacity of species to respond to climate change through phenotypic plasticity is limited suggesting that the species additionally need evolutionary adaptation to adjust to climate change. The observed selection on several growth-related and phenological traits indicates that the study species have the potential for future evolution in the context of a warming climate.

Frei, Esther R.; Ghazoul, Jaboury; Pluess, Andrea R.

2014-01-01

417

Clozapine-associated elevation of plasma cholinesterase  

Microsoft Academic Search

Objective The goal of this study was to identify adverse effects of the atypical neuroleptic clozapine on liver function and lipid\\u000a metabolism. Methods Data which included serum levels of clozapine and its hepatic metabolite N-desmethyl clozapine were collected from medical\\u000a records of patients treated with clozapine and controls. Results We identified a clozapine-associated marked elevation of plasma cholinesterase (ChE) with

Jens Wiltfang; Bettina Schenk-Daprá; Gerthild Stiens; Stefan Bleich; Borwin Bandelow; Peter Müller; Paul Dieter Niedmann; Victor William Armstrong; Eckart Rüther

2001-01-01

418

Refractivity estimation using multiple elevation angles  

Microsoft Academic Search

Estimation of the atmospheric refractivity is important for the prediction of radar performance. Surface or elevated trapping layers formed by the outflow of relatively dry and warm air over a cooler body of water often result in the refractive structure-supporting-convergence-zone-like behavior and multimodal effects. The propagation under such conditions can be very sensitive to even small changes in the vertical

Peter Gerstoft; L. Ted Rogers; William S. Hodgkiss; Lee J. Wagner

2003-01-01

419

Electrostatic Climber for Space Elevator and Launcher  

Microsoft Academic Search

Author details research on the new, very prospective, electrostatic Space Elevator climber based on a new electrostatic linear engine previously offered at the 42nd Joint Propulsion Conference (AIAA-2006-5229) and published in AEAT, Vol.78, No.6, 2006, pp. 502-508. The electrostatic climber discussed can have any speed (and braking), the energy for climber movement is delivered by a lightweight high-voltage line into

Alexander Bolonkin

2007-01-01

420

Digital Elevation Model Mosaic of Mercury  

NASA Technical Reports Server (NTRS)

At CEPS (Center for Earth and Planetary Studies) work has been underway since 2000 to semi-automatically stereo match all Mariner 10 stereo pairs. The resulting matched image coordinates are converted into longitude, latitude, and height points and then combined to form a map projected Digital Elevation Model (DEM) mosaic of the planet's surface. Stereo images from Mariner 10 cover one quarter of the planet's surface, mostly in the southern hemisphere. Additional information is contained in the original extended abstract.

Cook, A. C.; Watters, T. R.; Robinson, M. S.

2001-01-01

421

Optimized Global Digital Elevation Data Records (Invited)  

NASA Astrophysics Data System (ADS)

The Shuttle Radar Topography Mission (SRTM) used radar interferometry to map the Earth's topography between ±60° latitude - representing 80% of the land surface. The resulting digital elevation models bettered existing topographic data sets (including restricted military data) in accuracy, areal coverage and uniformity by several orders of magnitude, and the resulting data records have found broad application in most of the geosciences, military operations, even Google Earth. Despite their popularity the SRTM data have several limitations, including lack of coverage in polar regions and occasional small voids, or areas of no data in regions of high slope of low radar backscatter. Fortunately additional data sets have become available that, although lacking SRTM's data quality, are sufficient to mitigate many of these limitations. Primary among these is the Global Digital Elevation Model (GDEM) produced from ASTER stereo pairs. The MEaSUREs program is sponsoring an effort to merge these sets to produce and distribute an improved collection of data records that will optimize the topographic data, as well as make available additional non-topographic data products from the SRTM mission. There are four main areas of effort: (1) A systematic program to combine SRTM elevation data with those from other sensors, principally GDEM but also including SPOT stereo, the USGS’s National Elevation Data Set and others, to fill voids in the DEMs according to a prioritized plan, as well as extend the coverage beyond the current 60° latitude limit. (2) Combine the topographic data records with ICESat laser altimeter topography profiles to produce and distribute data records with enhanced ground control. (3) Document the existing SRTM radar image and ancillary data records, as well as generate image mosaics at multiple scales and distribute them via the world wide web. (4) Generate, document and distribute a standard and representative set of SRTM raw radar echo data, along with the appropriate ancillary tracking and pointing data necessary to process the echoes into DEMS using improved algorithms or

Kobrick, M.; Farr, T.; Crippen, R. E.

2009-12-01

422

Methods for structural design at elevated temperatures  

NASA Technical Reports Server (NTRS)

A procedure which can be used to design elevated temperature structures is discussed. The desired goal is to have the same confidence in the structural integrity at elevated temperature as the factor of safety gives on mechanical loads at room temperature. Methods of design and analysis for creep, creep rupture, and creep buckling are presented. Example problems are included to illustrate the analytical methods. Creep data for some common structural materials are presented. Appendix B is description, user's manual, and listing for the creep analysis program. The program predicts time to a given creep or to creep rupture for a material subjected to a specified stress-temperature-time spectrum. Fatigue at elevated temperature is discussed. Methods of analysis for high stress-low cycle fatigue, fatigue below the creep range, and fatigue in the creep range are included. The interaction of thermal fatigue and mechanical loads is considered, and a detailed approach to fatigue analysis is given for structures operating below the creep range.

Ellison, A. M.; Jones, W. E., Jr.; Leimbach, K. R.

1973-01-01

423

Elevated-Temperature Tribology of Metallic Materials  

SciTech Connect

The wear of metals and alloys takes place in many forms, and the type of wear that dominates in each instance is influenced by the mechanics of contact, material properties, the interfacial temperature, and the surrounding environment. The control of elevated-temperature friction and wear is important for applications like internal combustion engines, aerospace propulsion systems, and metalworking equipment. The progression of interacting, often synergistic processes produces surface deformation, subsurface damage accumulation, the formation of tribolayers, and the creation of free particles. Reaction products, particularly oxides, play a primary role in debris formation and microstructural evolution. Chemical reactions are known to be influenced by the energetic state of the exposed surfaces, and that surface energy is in turn affected by localized deformation and fracture. At relatively low temperatures, work-hardening can occur beneath tribo-contacts, but exposure to high temperatures can modify the resultant defect density and grain structure to affect the mechanisms of re-oxidation. As research by others has shown, the rate of wear at elevated temperatures can either be enhanced or reduced, depending on contact conditions and nature of oxide layer formation. Furthermore, the thermodynamic driving force for certain chemical reactions is moderated by kinetics and microstructure. The role of deformation, oxidation, and tribo-corrosion in the elevated temperature tribology of metallic alloys will be exemplified by three examples involving sliding wear, single-point abrasion, and repetitive impact plus slip.

Blau, Peter Julian [ORNL

2010-01-01

424

Groundwave Height-Gain Functions Near a Shoreline.  

National Technical Information Service (NTIS)

A saddlepoint approximation to a Kirchhoff integration over the surface of the Earth is used to derive formulas for the groundwave field for an elevated observer near a shoreline. It is shown that the transition from homogeneous groundwave propagation to ...

R. M. Jones

1984-01-01

425

Nucleus accumbens response to gains in reputation for the self relative to gains for others predicts social media use  

PubMed Central

Our reputation is important to us; we've experienced natural selection to care about our reputation. Recently, the neural processing of gains in reputation (positive social feedback concerning one's character) has been shown to occur in the human ventral striatum. It is still unclear, however, how individual differences in the processing of gains in reputation may lead to individual differences in real-world behavior. For example, in the real-world, one way that people currently maintain their reputation is by using social media websites, like Facebook. Furthermore, Facebook use consists of a social comparison component, where users observe others' behavior and can compare it to their own. Therefore, we hypothesized a relationship between the way the brain processes specifically self-relevant gains in reputation and one's degree of Facebook use. We recorded functional neuroimaging data while participants received gains in reputation, observed the gains in reputation of another person, or received monetary reward. We demonstrate that across participants, when responding to gains in reputation for the self, relative to observing gains for others, reward-related activity in the left nucleus accumbens predicts Facebook use. However, nucleus accumbens activity in response to monetary reward did not predict Facebook use. Finally, a control step-wise regression analysis showed that Facebook use primarily explains our results in the nucleus accumbens. Overall, our results demonstrate how individual sensitivity of the nucleus accumbens to the receipt of self-relevant social information leads to differences in real-world behavior.

Meshi, Dar; Morawetz, Carmen; Heekeren, Hauke R.

2013-01-01

426

High-gain observer design for loop transfer recovery  

Microsoft Academic Search

A systematic procedure of designing a high-gain observer which achieves asymptotic loop transfer recovery is given. The method allows assignment of different time-scales to an observer while permitting a chosen eigenstructure in each time-scale.

A. Saberi; P. Sannuti

1987-01-01

427

Raman gain measurements of thallium-tellurium oxide glasses  

NASA Astrophysics Data System (ADS)

Several different compositions of tellurium-thallium oxide glasses were fabricated and tested for their Raman gain performance. The addition of PbO to the glass matrix increased the surface optical damage threshold by 60-230%. The maximum material Raman gain coefficient experimentally obtained was (58 ± 3) times higher than the peak Raman gain of a 3.18 mm thick Corning 7980-2F fused silica sample (?? = 13.2 THz). The highest peak in the Raman gain spectrum of the tellurium-thallium glass is attributed to the presence of TeO3 and TeO3+1 structural units with thallium ions in the vicinity at a frequency shift near 21.3 THz.

Stegeman, Robert; Rivero, Clara; Richardson, Kathleen; Stegeman, George; Delfyett, Peter, Jr.; Guo, Yu; Pope, April; Schulte, Alfons; Cardinal, Thierry; Thomas, Philippe; Champarnaud-Mesjard, Jean-Claude

2005-02-01

428

Raman gain measurements of thallium-tellurium oxide glasses.  

PubMed

Several different compositions of tellurium-thallium oxide glasses were fabricated and tested for their Raman gain performance. The addition of PbO to the glass matrix increased the surface optical damage threshold by 60-230%. The maximum material Raman gain coefficient experimentally obtained was (58 +/- 3) times higher than the peak Raman gain of a 3.18 mm thick Corning 7980-2F fused silica sample (Deltanu = 13.2 THz). The highest peak in the Raman gain spectrum of the tellurium-thallium glass is attributed to the presence of TeO3 and TeO3+1 structural units with thallium ions in the vicinity at a frequency shift near 21.3 THz. PMID:19494983

Stegeman, Robert; Rivero, Clara; Richardson, Kathleen; Stegeman, George; Delfyett, Peter; Guo, Yu; Pope, April; Schulte, Alfons; Cardinal, Thierry; Thomas, Philippe; Champarnaud-Mesjard, Jean-Claude

2005-02-21

429

Perspective methods for the generation of COIL gain medium  

NASA Astrophysics Data System (ADS)

An ejector nozzle bank powered by centrifugal bubbling SOG is considered like highly efficient gain generating system for COIL. A high potential recovered pressure ~100 torr of the gain medium flow with a small signal gain higher than 1% cm -1 and low oxygen plenum pressure has been demonstrated. A centrifugal bubbling SOG is an efficient source of oxygen at high pressure with high depletion of the BHP in the single burn dawn. A high 0 II(1?) yield and chlorine utilization higher than 90% have been obtained at chlorine gas loading up to 6 mmole/s per 1 cm2 of the bubbler surface. The ejector COIL powered by centrifugal bubbling SOG demonstrated ~25% of chemical efficiency with specific power 6 kJ per 1 litre of the BHP in the single burn dawn. The combination of centrifugal bubble SOG with ejector nozzle bank can be considered as a promising gain medium flow generation system for COIL.

Zagidullin, Marsel V.; Nikolaev, Valery D.; Svistun, Michael I.; Khvatov, Nikolay A.

2007-04-01

430

Predicting FCI gain with a nonverbal intelligence test  

NSDL National Science Digital Library

We have administered both a commercial, nonverbal intelligence test (the GAMA) and Lawsonâs Classroom Test of Scientific Reasoning to students in two introductory physics classes to determine if either test can successfully predict normalized gains on the Force Concept Inventory. Since gain on the FCI is known to be related to gender, we adopted a linear model with gain on the FCI as the dependent variable and gender and a test score as the independent variables. We found that the GAMA score did not predict a significant amount of variation beyond gender. Lawsonâs test, however, did predict a small but significant variation beyond gender. When simple linear regressions were run separately for males and females with the Lawson score as a predictor, we found that the Lawson score did not significantly predict gains for females but was a marginally significant predictor for males.

Semak, M. R.; Dietz, R. D.; Pearson, R. H.; Willis, C. W.

2014-02-01

431

Gain Issues for Fast Ignition. Heavy Ion Fusion Symposium.  

National Technical Information Service (NTIS)

The authors constructed a fast ignitor gain model based a few ingredients: atzeni ignition power, intensity, energy model; hydrodynamic efficiency, in-flight-aspect-ratio (IFAR) from rocket equation using degenerate gas DT EOS; Ponderomotive scaling model...

M. Tabak D. Callahan

2004-01-01

432

Avalanche Multiplication as a Gain Mechanism in Photodiodes.  

National Technical Information Service (NTIS)

The feasibility of a fast, high-gain photodetector based on the phenomenon of avalanche multiplication in semiconductors has been investigated. Such a detector would be a definite requirement for communication systems using light as a carrier, as well as ...

H. W. Ruegg

1966-01-01

433

Gain-assisted control of the Goos-Haenchen shift  

SciTech Connect

A gain-assisted model is considered to study the Goos-Haenchen (GH) shift behavior in the reflected and transmitted light. In this model, a probe light is incident on a cavity containing three-level dilute gaseous atomic medium. The atom-field interaction follows two-photon Raman transitions, and the dielectric susceptibility of the medium exhibits dispersion and gain properties [L. J. Wang, A. Kuzmich, and A. Dogariu, Nature (London) 406, 227 (2000)]. Under appropriate conditions, two gain peaks are observed with anomalous dispersion between the peaks, whereas normal dispersion can be observed at and around the gain maxima. The manipulation of the detuning associated with the probe light field which interacts with the intracavity medium during its propagation through the cavity can lead to a control over negative and positive GH shift in the reflected and transmitted light beam via the anomalous and normal dispersion of the medium.

Ziauddin,; Qamar, Sajid [Centre for Quantum Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan)

2011-11-15

434

Losing it: The Influence of Losses on Individuals' Normalized Gains  

NSDL National Science Digital Library

Researchers and practitioners routinely use the normalized gain (Hake, 1998) to evaluate the effectiveness of instruction. Normalized gain (g) has been useful in distinguishing active engagement from traditional instruction. Recently, concerns were raised about normalized gain because it implicitly neglects retention (or, equivalently, "losses"). That is to say, g assumes no right answers become wrong after instruction. We analyze individual standardized gain (G) and loss (L) in data collected at Harvard University during the first five years that Peer Instruction was developed. We find that losses are non-zero, and that losses are larger among students with lower pre-test performances. These preliminary results warrant further research, particularly with different student populations, to establish whether the failure to address loss changes the conclusions drawn from g.

Miller, Kelly; Lasry, Nathaniel; Reshef, Orad; Dowd, Jason E.; Araujo, Ives; Mazur, Eric

2010-12-31

435

Neonatal Outcome and Weight Gain of Black Adolescents.  

National Technical Information Service (NTIS)

The study investigated the relationship between maternal weight gain and neonatal outcome (primarily birthweight and gestational age) for black adolescent and adult women of lower socioeconomic status. By comparing young adolescents (YA), older adolescent...

E. R. McAnarney

1989-01-01

436

1300-nm gain obtained with dysprosium-doped chloride crystals  

SciTech Connect

Dy{sup 3+} - doped chloride crystals have high 1300-nm emission quantum yields. Pump - probe experiments on La Cl{sub 3}:Dy{sup 3+} demonstrate optical gain consistent with predictions based on spectroscopic cross sections and lifetimes.

Page, R.H.; Schaffers, K.I.; Beach, R.J.; Payne, S.A.; Krupke, W.F.

1996-03-01

437

34 CFR 462.43 - How is educational gain measured?  

Code of Federal Regulations, 2013 CFR

...OFFICE OF VOCATIONAL AND ADULT EDUCATION, DEPARTMENT OF EDUCATION MEASURING EDUCATIONAL GAIN...REPORTING SYSTEM FOR ADULT EDUCATION What Requirements Must...providers to test students in reading and numeracy. The...

2013-07-01

438

Gain-Assisted Superluminal Propagation in Coupled Optical Resonators  

NASA Technical Reports Server (NTRS)

We predict superluminal pulse propagation in co-resonant coupled optical resonators, when a gain element is placed in the resonator closest to the excitation waveguide, provided the resonator farthest from the excitation waveguide is under-coupled.

Chang, Hong-Rok; Smith, David D.

2004-01-01

439

Pinned modes in lossy lattices with local gain and nonlinearity.  

PubMed

We introduce a discrete linear lossy system with an embedded "hot spot" (HS), i.e., a site carrying linear gain and complex cubic nonlinearity. The system can be used to model an array of optical or plasmonic waveguides, where selective excitation of particular cores is possible. Localized modes pinned to the HS are constructed in an implicit analytical form, and their stability is investigated numerically. Stability regions for the modes are obtained in the parameter space of the linear gain and cubic gain or loss. An essential result is that the interaction of the unsaturated cubic gain and self-defocusing nonlinearity can produce stable modes, although they may be destabilized by finite-amplitude perturbations. On the other hand, the interplay of the cubic loss and self-defocusing gives rise to a bistability. PMID:23031046

Malomed, Boris A; Ding, Edwin; Chow, K W; Lai, S K

2012-09-01

440

ADHD Drugs Linked to Later Weight Gain in Kids  

MedlinePLUS

... ADHD Drugs Linked to Later Weight Gain in Kids Study found 'rebound' effect in children who stopped ... weight differences seem to be most pronounced for kids who had taken stimulant medications to control their ...

441

Mother's Pregnancy Weight Gain May Influence Child's Obesity Risk  

MedlinePLUS

... JavaScript. Mother's Pregnancy Weight Gain May Influence Child's Obesity Risk Study found that either too few or ... Preidt Tuesday, April 15, 2014 Related MedlinePlus Pages Obesity in Children Pregnancy Weight Control TUESDAY, April 15, ...

442

Anthropogenic Elevation Change in the Pacific Northwest  

NASA Astrophysics Data System (ADS)

Over the past few decades, interferometric synthetic aperture radar (InSAR) has emerged as a valuable tool for studying crustal deformation signals. Its applications to studies of tectonic and non-tectonic sources are varied, including earthquakes and fault-related processes, volcanic deformation, vegetation structure, and anthropogenic signals. In addition to studies of crustal deformation, the sensitivity of interferometric phase to topography makes InSAR a superb tool for the generation of digital elevation models (DEMs). While much of the focus of InSAR research in recent years has been on deformation, changes in the elevation of the ground surface can be of great scientific or societal interest as well. Examples include elevation and volume change due to anthropogenic processes such as landfill and open-pit mining operations, and natural processes such as glacier thinning or terrain alteration resulting from effusive volcanic eruptions. Our study describes two elevation change signals observed in the Pacific Northwest that are of anthropogenic origin. Using the baseline-dependent nature of the topographic component of interferometric phase, we have determined a proxy for canopy height using coherent interferometric phase differences between adjacent logged and forested regions, as well as a means for determining estimates of the amount and time history of material displaced during mining operations at the Centralia Coal Mine in Centralia, Washington. Quantifying the amount of surface change due to anthropogenic activities is not only critical for tracking the altering landscape of the Pacific Northwest and reducing the observed error in interferograms attributable to elevation change. Deforestation is one of the most significant contributors to global carbon emissions, and quantifying changes in vegetation structure can assist in efforts to monitor and mitigate the effects of deforestation on climate change. Similarly, mining operations can have a lasting impact on surrounding communities due to triggered seismicity, landslides, and groundwater disruption or contamination. In both examples, our focus on phase differences across short spatial scales reduces the impact of some of the main sources of error in interferograms, such as atmospheric water vapor variations and errors in the satellite orbital positions.

Prush, V. B.; Lohman, R. B.

2013-12-01

443

An adaptive high-gain observer for nonlinear systems  

Microsoft Academic Search

In this paper we present a high-gain observer for a general class of nonlinear SISO systems for which the high-gain parameter is determined on-line in an adaptive fashion. The adaptation scheme is simple and universal in the sense that it is independent of the system the observer is designed for. We prove that the observer output error becomes smaller than

Eric Bullinger; Frank Allgower

1997-01-01

444

Gain-guided and dispersion-managed soliton fiber lasers  

Microsoft Academic Search

Gain-guided solitons are experimentally observed in dispersion-managed fiber lasers with net positive group velocity dispersion. In contrast to the conventional solitons generated in fiber lasers with net negative dispersion, gain-guided solitons have steep spectral edge(s), large pulse width and broader bandwidth, which are also different to the dispersion-managed solitons generated in fiber lasers with net positive but near zero dispersion

L. M. Zhao; D. Y. Tang; T. H. Cheng; C. Lu

2006-01-01

445

What Do Students Gain by Engaging in Socioscientific Inquiry?  

Microsoft Academic Search

The question of what students gain by engaging in socioscientific inquiry is addressed in two ways. First, relevant literature\\u000a is surveyed to build the case that socioscientific issues (SSI) can serve as useful contexts for teaching and learning science\\u000a content. Studies are reviewed which document student gains in discipline specific content knowledge as well as understandings\\u000a of the nature of

Troy D. Sadler; Sasha A. Barab; Brianna Scott

2007-01-01

446

Motor memory in childhood: early expression of consolidation phase gains.  

PubMed

Are children faster than adults in consolidating procedural knowledge? In adults, the expression of the full benefits of motor practice requires a few hours of consolidation and sleep. Here we show that, although the processes generating the delayed gains continued beyond the first few hours post-training, children expressed significant gains as early as 1 h post-training, in the awake state. PMID:23867636

Ashtamker, Lilach; Karni, Avi

2013-11-01

447

The bias in current measures of gestational weight gain  

PubMed Central

Summary Conventional measures of gestational weight gain (GWG), such as average rate of weight gain, are likely correlated with gestational duration. Such correlation could introduce bias to epidemiologic studies of GWG and adverse perinatal outcomes because many perinatal outcomes are also correlated with gestational duration. This study aimed to quantify the extent to which currently-used GWG measures may bias the apparent relation between maternal weight gain and risk of preterm birth. For each woman in a provincial perinatal database registry (British Columbia, Canada, 2000–2009), a total GWG was simulated such that it was uncorrelated with risk of preterm birth. The simulation was based on serial antenatal GWG measurements from a sample of term pregnancies. Simulated GWGs were classified using 3 approaches: total weight gain (kg), average rate of weight gain (kg/week) or adequacy of gestational weight gain in relation to Institute of Medicine recommendations, and their association with preterm birth ? 32 weeks was explored using logistic regression. All measures of GWG induced an apparent association between GWG and preterm birth ?32 weeks even when, by design, none existed. Odds ratios in the lowest fifths of each GWG measure compared with the middle fifths ranged from 4.4 [95% CI 3.6, 5.4] (total weight gain) to 1.6 [95% CI 1.3, 2.0] (Institute of Medicine adequacy ratio). Conventional measures of GWG introduce serious bias to the study of maternal weight gain and preterm birth. A new measure of GWG that is uncorrelated with gestational duration is needed.

Hutcheon, Jennifer A; Bodnar, Lisa M; Joseph, KS; Abrams, Barbara; Simhan, Hyagriv N; Platt, Robert W

2014-01-01

448

A Bandpass Filter With Inherent Gain Adaptation for Hearing Applications  

Microsoft Academic Search

In this paper, we propose a novel bandpass filter design that incorporates automatic gain control (AGC). The gain control in the filter reduces the performance requirements of a wide-band AGC, and allows for low-power multichannel compression. The filter achieves up to 15 dB of compression on a 55-dB input dynamic range and is tunable over the audio frequency range, with

Kofi M. Odame; David V. Anderson; Paul Hasler

2008-01-01

449

Gain lever characterization in monolithically integrated diode lasers  

Microsoft Academic Search

Gain Lever, an effect for enhancing amplitude modulation (AM) efficiency in multisection laser diodes1, has been characterized in InGaAs DQW edge emitting lasers that are integrated with passive waveguides. Specifically designed structures which give a range of split ratios from 1:1 to 9:1 have been fabricated and measured to fully characterize the parameter space for operation in the gain lever

Michael Pocha; Tiziana Bond; Rebecca Welty; Stephen Vernon; Jeffrey Kallman; Elaine Behymer

2005-01-01

450

Recent Progress in High-Gain FEL Theory  

SciTech Connect

High-gain free electron lasers (FEL) are being developed as extremely bright x-ray sources of a next-generation radiation facility. In this paper, we review the basic theory and the recent progress in understanding the startup, the exponential growth and the saturation of the high-gain process, emphasizing the self-amplified spontaneous emission (SASE). We will also discuss how the FEL performance may be affected by various errors and wakefield effects in the undulator.

Huang, Z.; /SLAC

2005-09-30

451

Low voltage gain boosting schemes for one stage operational amplifiers  

Microsoft Academic Search

Two simple schemes for boosting significantly the open loop gain of one stage op-amps without essential degradation of the phase margin are discussed. These are based on low voltage active current mirrors using multiple cascoded auxiliary amplifiers to achieve extremely high output resistance. Post-layout simulations show that open loop gain greater than 300 dB with phase margin greater 60deg can

Jaime Ramírez-Angulo; Annajirao Garimella; L. M. Kalyani-Garimella Milind Sawant; A. Lopez-Martin; R. G. Carvajal

2007-01-01

452

Soft-switching interleaved boost converter with high voltage gain  

Microsoft Academic Search

In this paper a soft-switching interleaved boost converter with high voltage gain is presented. The high voltage gain converter is far suitable for applications where a high step-up voltage is required, as in some renewable energy systems, which use, for example, photovoltaic panels and\\/or fuel cells. Besides, in order to guarantee small switching losses and, consequently, a high efficiency, a

R. N. A. L. Silva; G. A. L. Henn; P. P. Praca; L. H. S. C. Barreto; D. S. Oliveira Jr; F. L. M. Antunes

2008-01-01

453

Superradiance in the high-gain free-electron laser  

Microsoft Academic Search

In this paper we describe the effects of slippage on the single-pass high-gain free-electron laser (FEL) amplifier. We use a one-dimensional computational code to show the existence of two new dynamical regimes characterized by a dimensionless parameter K, which is a measure of the slippage in one gain length. We define the long-pulse limit to be when K<<1 or the

R. Bonifacio; B. W. J. McNeil; P. Pierini

1989-01-01

454

Neighborhood socioeconomic disadvantage and gestational weight gain and loss.  

PubMed

We explored the relationship between neighborhood socioeconomic disadvantage (NSED) and gestational weight gain and loss and if the association differed by race. A census tract level NSED index (categorized as low, mid-low, mid-high, and high) was generated from 12 measures from the 2000 US Census data. Gestational weight gain and other individual-level characteristics were derived from vital birth records for Allegheny County, PA for 2003-2010 (n = 55,608). Crude and adjusted relative risks were estimated using modified multilevel Poisson regression models to estimate the association between NSED and excessive and inadequate gestational weight gain (GWG) and weight loss (versus adequate GWG). Black women lived in neighborhoods that were more likely to be socioeconomically disadvantaged compared to white women. Almost 55 % of women gained an excessive amount of weight during pregnancy, and 2 % lost weight during pregnancy. Black women were more likely than white women to have inadequate weight gain or weight loss. Mid-high (aRR = 1.3, 95 % CI 1.2, 1.3) and high (aRR = 1.5, 95 % CI 1.5, 1.6) NSED compared to low NSED was associated with inadequate weight gain while NSED was not associated with excessive weight gain. Among black women, high versus low NSED was associated with weight loss during pregnancy (RR = 1.6, 95 % CI 1.1, 2.5). Among white women, each level of NSED compared to low NSED was associated with weight loss during pregnancy. This study demonstrates how neighborhood socioeconomic characteristics can contribute to our understanding of inadequate weight gain and weight loss during pregnancy, having implications for future research and interventions designed to advance pregnancy outcomes. PMID:24026397

Mendez, Dara D; Doebler, Donna Almario; Kim, Kevin H; Amutah, Ndidi N; Fabio, Anthony; Bodnar, Lisa M

2014-07-01

455

Highly charged ion energy gain spectroscopy of molecular excitations  

NASA Astrophysics Data System (ADS)

We show that the measurement at high resolution of the kinetic-energy gain spectrum of a highly charged ion (HCI) scattered and partly neutralised by a molecule, a nanocluster or a surface can reveal the excitation spectrum of the target. As a first application of the analysis, we demonstrate that the periodic oscillations in the measured energy gain spectra of energetic Ar q+ ions flying by C 60 molecules arise from the coherent multiple excitations of C 60 plasmons.

Lucas, A. A.; Benedek, G.; Sunjic, M.; Echenique, P. M.

2010-06-01

456

Gain-scheduled wheel slip control in automotive brake systems  

Microsoft Academic Search

A wheel slip controller is developed and experimentally tested in a car equipped with electromechanical brake actuators and a brake-by-wire system. A gain scheduling approach is taken, where the vehicle speed is viewed as a slowly time-varying parameter and the model is linearized about the nominal wheel slip. Gain matrices for the different operating conditions are designed using an LQR

Tor A. Johansen; Idar Petersen; Jens Kalkkuhl; Jens Ludemann

2003-01-01

457

Evaluation of Experimental Data from the GAINS Balloon GPS Surface Reflection Instrument  

NASA Technical Reports Server (NTRS)

The GPS Surface Reflection Instrument was integrated as an experiment on the GAINS (Global Airocean IN-situ System) 48-hour balloon mission flown in September 2001. The data collected by similar instruments in the past has been used to measure sea state from which ocean surface winds can be accurately estimated. The GPS signal has also been shown to be reflected from wetland areas and even from subsurface moisture. The current version of the instrument has been redesigned to be more compact, use less power, and withstand a greater variation in environmental conditions than previous versions. This instrument has also incorporated a new data collection mode to track 5 direct satellites (providing a continuous navigation solution) and multiplex the remaining 7 channels to track the reflected signal of the satellite tracked in channel 0. The new software mode has been shown to increase the signal to noise ratio of the collected data and enhance the science return of the instrument. During the 48-hour flight over the Northwest US, the instrument will measure surface reflections that can be detected over the balloon's ground track. Since ground surface elevations in this area vary widely from the WGS-84 ellipsoid altitude, the instrument software has been modified to incorporate a surface altitude correction based on USGS 30-minute Digital Elevation Models. Information presented will include facts about instrument design goals, data collection methodologies and algorithms, and results of the science data analyses for the 48-hour mission.

Gance, George G.; Johnson, Thomas A.

2004-01-01

458

Physiologic and metabolic responses of wheat seedlings to elevated and super-elevated carbon dioxide  

NASA Astrophysics Data System (ADS)

The metabolic consequence of suboptimal (400 ?mol mol -1 or ppm), near-optimal (1500 ppm) and supra-optimal (10,000 ppm) atmospheric carbon dioxide concentrations [CO 2] was investigated in an attempt to reveal plausible underlying mechanisms for the differential physiological and developmental responses to increasing [CO 2]. Both non-targeted and targeted metabolite profiling by GC-MS and LC-MS were employed to examine primary and secondary metabolites in wheat ( Triticum aestivum, cv Yocoro rojo) continuously exposed to these [CO 2] levels for 14, 21 and 28 days. Metabolite profile was altered by both [CO 2] and physiological age. In general, plants grown under high [CO 2] exhibited a metabolite profile characteristic of older plants under ambient CO 2. Elevated [CO 2] resulted in higher levels of phosphorylated sugar intermediates, though no clear trend in the content of reducing sugars was observed. Transient starch content was enhanced by increasing [CO 2] to a much greater extent at 10,000 ppm CO 2 than at 1500 ppm CO 2. The percentage increase of starch content resulting from CO 2 enrichment declined as plants develope. In contrast, elevated [CO 2] promoted the accumulation of secondary metabolites (flavonoids) progressively to a greater extent as plants became mature. Elevated [CO 2] to 1500 ppm induced a higher initial growth rate, while super-elevated [CO 2] appeared to negate such initial growth promotion. However, after 4 weeks, there was no difference in vegetative growth between 1500 and 10,000 ppm CO 2-grown plants, both elevated CO 2 levels resulted in an overall 25% increase in biomass over the control plants. More interestingly, elevated atmospheric [CO 2] reduced evapotranspiration rate (ET), but further increase to the supra-optimal level resulted in increased ET (a reversed trend), i.e. ET at 1500 ppm < ET at 10,000 ppm < ET at 400 ppm. The differential effect of elevated and super-elevated CO 2 on plants was further reflected in the nitrogen dynamics. These results provide the potential metabolic basis for the differential productivity and stomatal function of plants grown under elevated and super-elevated CO 2 levels.

Levine, Lanfang H.; Kasahara, Hirokazu; Kopka, Joachim; Erban, Alexander; Fehrl, Ines; Kaplan, Fatma; Zhao, Wei; Littell, Ramon C.; Guy, Charles; Wheeler, Raymond; Sager, John; Mills, Aaron; Levine, Howard G.

2008-12-01

459

Tissue microarray analysis of cyclin D1 gene amplification and gain in colorectal carcinomas.  

PubMed

Colorectal cancer is one of the most common neoplastic diseases and one of the leading causes of cancer-related deaths. Elevated beta-catenin levels in colorectal cancer result in the binding of beta-catenin to LEF-1 and increased transcriptional activation of the CCND1 gene. Overexpression of cyclin D1 is observed in one third of colorectal tumors. CCND1 amplification is the main cause of protein overexpression in numerous human carcinomas. In colorectal cancer, however, no CCND1 amplification has been reported so far. The aim of this study was to determine the frequency of CCND1 amplifications and gains in a large number of colorectal carcinomas, arranged in a tissue microarray, in order to assess their role in colorectal cancer development. The copy number changes, detected by fluorescence in situ hybridization, were predominantly gains (7.6%) and only rarely amplifications (2.5%). In colorectal cancer, the CCND1 copy number increase was neither associated with the tumor phenotype (stage and grade) nor with the tumor localization (colon, rectum or sigmoid colon). In conclusion, even in a small number of colorectal tumors, CCND1 gene amplification is a possible mechanism for the increase in cyclin D1 oncoprotein. PMID:15557752

Toncheva, D; Petrova, D; Tzenova, V; Dimova, I; Yankova, R; Yordanov, V; Damjanov, D; Todorov, T; Zaharieva, B

2004-01-01

460

Radiation force corrections to planar wiggler FEL gain  

NASA Astrophysics Data System (ADS)

The longitudinal electron dynamics in an FEL are governed by the coupling of the electrons transverse velocity, V?, to the combined magnetic fields of the wiggler and radiation in the Lorentz force equation. The derivation of the "standard" gain expression neglects the radiation contribution to V? and assumes V? results from the wiggler field alone [1]. We show, however, that the radiation contribution to V? couples with the wiggler field to produce a force of the same order as that from the wiggler field coupling with the radiation field [2]. When this former force, the "radiation force", is included in the electron dymanics, the "difference of Bessel function factor" in the pendulum equation differs significantly from that of the standard expression, being given by: {1}/{2}1+ {1}/{f}J {(f-1)}/{2}(f?)- 1- {1}/{f}J {(f+1)}/{2}(f?) (-1) {(f-1)}/{2} instead of {J {(f-1)}/{2}(f?)-J {(f+1)}/{2}(f?)}(-1) {(f-1)}/{2} The gain is then proportional to the product of these two factors, rather than the square of the latter. The corrections to the pendulum/gain expressions result in approximately a 20% increase in gain at the fundamental but a 20% decrease in gain at the third harmonic for deflection parameter K = 2. The standard expressions for helical wiggler gain and spontaneous emission cross-sections are unaffected by inclusion of the radiation force term.

McNeil, B. W. J.; Firth, W. J.

1986-09-01

461

Gains in accuracy from averaging ratings of abnormality  

NASA Astrophysics Data System (ADS)

Six radiologists used continuous scales to rate 529 chest-film cases for likelihood of five separate types of abnormalities (interstitial disease, nodules, pneumothorax, alveolar infiltrates and rib fractures) in each of six replicated readings, yielding 36 separate ratings of each case for the five abnormalities. Analyses for each type of abnormality estimated the relative gains in accuracy (area below the ROC curve) obtained by averaging the case-ratings across: (1) six independent replications by each reader (30% gain), (2) six different readers within each replication (39% gain) or (3) all 36 readings (58% gain). Although accuracy differed among both readers and abnormalities, ROC curves for the median ratings showed similar relative gains in accuracy. From a latent-variable model for these gains, we estimate that about 51% of a reader's total decision variance consisted of random (within-reader) errors that were uncorrelated between replications, another 14% came from that reader's consistent (but idiosyncratic) responses to different cases, and only about 35% could be attributed to systematic variations among the sampled cases that were consistent across different readers.

Swensson, Richard G.; King, Jill L.; Gur, David; Good, Walter F.

1999-05-01

462

A neurochemical approach to valuation sensitivity over gains and losses  

PubMed Central

Prospect theory proposes the hypothesis that people have diminishing sensitivity in valuing increases in the size of monetary outcomes, for both gains and losses. For decision-making under risk, this implies a tendency to be risk-tolerant over losses while being generally risk averse over gains. We offer a neurochemistry-based model of the diminishing valuation sensitivity hypothesis. Specifically, we propose that dopamine tone modulates the sensitivity towards valuation of gains while serotonin tone modulates the sensitivity towards valuation of losses. Consequently, higher dopamine tone would yield a more concave valuation function over gains while higher serotonin tone would yield a more convex valuation function over losses. Using a neurogenetics strategy to test our neurochemical model, we find that subjects with the 9-repeat allele of DAT1 (lower DA tone) are more risk-tolerant over gains than subjects with the 10-repeat allele, and that subjects with the 10-repeat allele of STin2 (higher 5HT tone) are more risk-tolerant over losses than subjects with the 12-repeat allele. Overall, our results support the implications of our model and provide the first neurogenetics evidence that risk attitudes are partially hard-wired in differentiating between gain- and loss-oriented risks.

Zhong, Songfa; Israel, Salomon; Xue, Hong; Sham, Pak C.; Ebstein, Richard P.; Chew, Soo Hong

2009-01-01

463

Gain saturation in InGaN superluminescent diodes  

NASA Astrophysics Data System (ADS)

The gain saturation is a crucial factor limiting achievable output power of superluminescent diodes (SLD), as it exponentially depends on optical gain value. Contrary to laser diodes, in SLDs gain is increasing with the increasing current even much above the transparency conditions. Therefore, SLDs provide us with an unique possibility to examine gain under high current densities (high carrier injection). In our work we examined SLDs fabricated in a "j-shape" ridge-waveguide geometry having chips of the length of 700 ?m and 1000 ?m, emitting in the blue-violet region. By comparing the amplified spontaneous emission measured along the device waveguide with true spontaneous emission measured in perpendicular direction, we are able to extract optical gain as a function of injected current. We show, that in our devices spontaneous emission exhibits a square-root-like dependence on current which is commonly associated with the presence of "droop" in case of nitride light emitting diodes. However, along the waveguide axis, fast processes of stimulated recombination dominate which eliminates the efficiency reduction. Calculated optical gain shows a substantial saturation for current densities above 8 kA/cm2.

Kafar, Anna; Stanczyk, Szymon; Targowski, Grzegorz; Suski, Tadek; Perlin, Piotr

2014-03-01

464

Gain Control Network Conditions in Early Sensory Coding  

PubMed Central

Gain control is essential for the proper function of any sensory system. However, the precise mechanisms for achieving effective gain control in the brain are unknown. Based on our understanding of the existence and strength of connections in the insect olfactory system, we analyze the conditions that lead to controlled gain in a randomly connected network of excitatory and inhibitory neurons. We consider two scenarios for the variation of input into the system. In the first case, the intensity of the sensory input controls the input currents to a fixed proportion of neurons of the excitatory and inhibitory populations. In the second case, increasing intensity of the sensory stimulus will both, recruit an increasing number of neurons that receive input and change the input current that they receive. Using a mean field approximation for the network activity we derive relationships between the parameters of the network that ensure that the overall level of activity of the excitatory population remains unchanged for increasing intensity of the external stimulation. We find that, first, the main parameters that regulate network gain are the probabilities of connections from the inhibitory population to the excitatory population and of the connections within the inhibitory population. Second, we show that strict gain control is not achievable in a random network in the second case, when the input recruits an increasing number of neurons. Finally, we confirm that the gain control conditions derived from the mean field approximation are valid in simulations of firing rate models and Hodgkin-Huxley conductance based models.

Serrano, Eduardo; Nowotny, Thomas; Levi, Rafael; Smith, Brian H.; Huerta, Ramon

2013-01-01

465

What controls gain in gain control? Mismatch negativity (MMN), priors and system biases.  

PubMed

Repetitious patterns enable the auditory system to form prediction models specifying the most likely characteristics of subsequent sounds. Pattern deviations elicit mismatch negativity (MMN), the amplitude of which is modulated by the size of the deviation and confidence in the model. Todd et al. (Neuropsychologia 49:3399-3405, 2011; J Neurophysiol 109:99-105, 2013) demonstrated that a multi-timescale sequence reveals a bias that profoundly distorts the impact of local sound statistics on the MMN amplitude. Two sounds alternate roles as repetitious "standard" and rare "deviant" rapidly (every 0.8 min) or slowly (every 2.4 min). The bias manifests as larger MMN to the sound first encountered as deviant in slow compared to fast changing sequences, but no difference for the sound first encountered as a standard. We propose that the bias is due to how Bayesian priors shape filters of sound relevance. By examining the time-course of change in MMN amplitude we show that the bias manifests immediately after roles change but rapidly disappears thereafter. The bias was reflected in the response to deviant sounds only (not in response to standards), consistent with precision estimates extracted from second order patterns modulating gain differentially for the two sounds. Evoked responses to deviants suggest that pattern extraction and reactivation of priors can operate over tens of minutes or longer. Both MMN and deviant responses establish that: (1) priors are defined by the most proximally encountered probability distribution when one exists but; (2) when no prior exists, one is instantiated by sequence onset characteristics; and (3) priors require context interruption to be updated. PMID:24343248

Todd, Juanita; Heathcote, Andrew; Mullens, Daniel; Whitson, Lisa R; Provost, Alexander; Winkler, István

2014-07-01

466

Gain-of-function mutant p53 upregulates CXC chemokines and enhances cell migration.  

PubMed

The role of dominant transforming p53 in carcinogenesis is poorly understood. Our previous data suggested that aberrant p53 proteins can enhance tumorigenesis and metastasis. Here, we examined potential mechanisms through which gain-of-function (GOF) p53 proteins can induce motility. Cells expressing GOF p53 -R175H, -R273H and -D281G showed enhanced migration, which was reversed by RNA interference (RNAi) or transactivation-deficient mutants. In cells with engineered or endogenous p53 mutants, enhanced migration was reduced by downregulation of nuclear factor-kappaB2, a GOF p53 target. We found that GOF p53 proteins upregulate CXC-chemokine expression, the inflammatory mediators that contribute to multiple aspects of tumorigenesis. Elevated expression of CXCL5, CXCL8 and CXCL12 was found in cells expressing oncogenic p53. Transcription was elevated as CXCL5 and CXCL8 promoter activity was higher in cells expressing GOF p53, whereas wild-type p53 repressed promoter activity. Chromatin immunoprecipitation assays revealed enhanced presence of acetylated histone H3 on the CXCL5 promoter in H1299/R273H cells, in agreement with increased transcriptional activity of the promoter, whereas RNAi-mediated repression of CXCL5 inhibited cell migration. Consistent with this, knockdown of the endogenous mutant p53 in lung cancer or melanoma cells reduced CXCL5 expression and cell migration. Furthermore, short hairpin RNA knockdown of mutant p53 in MDA-MB-231 cells reduced expression of a number of key targets, including several chemokines and other inflammatory mediators. Finally, CXCL5 expression was also elevated in lung tumor samples containing GOF p53, indicating relevance to human cancer. The data suggest a mechanistic link between GOF p53 proteins and chemokines in enhanced cell motility. PMID:22114072

Yeudall, W Andrew; Vaughan, Catherine A; Miyazaki, Hiroshi; Ramamoorthy, Mahesh; Choi, Mi-Yon; Chapman, Christopher G; Wang, Huixin; Black, Elena; Bulysheva, Anna A; Deb, Swati Palit; Windle, Brad; Deb, Sumitra

2012-02-01

467

The associations of viral and mycoplasmal antibody titers with respiratory disease and weight gain in feedlot calves.  

PubMed Central

Blood samples from 32 groups of calves (n = 700) were taken on arrival and after 28-35 days at the feedlot. Eleven groups were housed in feedlots in Ontario, and 21 groups in feedlots in Alberta. Serum antibody titers to bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), parainfluenza virus type 3 (PIV-3), infectious bovine rhinotracheitis virus (IBRV), Mycoplasma dispar and M. bovis, plus data on bovine corona virus (BCV) from a previous study were investigated for their association with the risk of bovine respiratory disease (BRD), and with 28-day weight change, both before and after controlling for titers to Pasteurella haemolytica and Haemophilus somnus. Exposure to IBRV and M. bovis was infrequent, and although exposure to PIV-3 was more common, none of these agents had important associations with BRD. Higher titers to BVDV, BRSV, and BCV on arrival were associated with reduced risks of BRD and increased weight gains. However, there was some variation in these relationships and higher arrival titers to BVDV and BRSV in a subset of the calves were associated with increased risks of BRD. Titer increases to BVDV were associated with a higher risk of BRD and lower weight gains. Titer increases to BRSV were not usually associated with the occurrence of BRD, but titer increases to BRSV in a subset of calves that were vaccinated against BRSV, on arrival, were associated with an elevated risk of BRD. Of all the agents studied, BVDV had the most consistent associations with elevated risk of BRD and lower weight gains. Higher BRSV arrival titers were related to lower risk of BRD and higher weight gains; in some instances titer increases to BRSV were associated with higher BRD risk. Higher titers to BCV on arrival were related to reduced risks of BRD. Practical ways of adequately preventing the negative effects of these agents are still needed.

Martin, S W; Nagy, E; Armstrong, D; Rosendal, S

1999-01-01

468

Surface elevation change and susceptibility of different mangrove zones to sea-level rise on Pacific high islands of Micronesia  

USGS Publications Warehouse

Mangroves on Pacific high islands offer a number of important ecosystem services to both natural ecological communities and human societies. High islands are subjected to constant erosion over geologic time, which establishes an important source of terrigeneous sediment for nearby marine communities. Many of these sediments are deposited in mangrove forests and offer mangroves a potentially important means for adjusting surface elevation with rising sea level. In this study, we investigated sedimentation and elevation dynamics of mangrove forests in three hydrogeomorphic settings on the islands of Kosrae and Pohnpei, Federated States of Micronesia (FSM). Surface accretion rates ranged from 2.9 to 20.8 mm y-1, and are high for naturally occurring mangroves. Although mangrove forests in Micronesian high islands appear to have a strong capacity to offset elevation losses by way of sedimentation, elevation change over 61/2 years ranged from -3.2 to 4.1 mm y-1, depending on the location. Mangrove surface elevation change also varied by hydrogeomorphic setting and river, and suggested differential, and not uniformly bleak, susceptibilities among Pacific high island mangroves to sea-level rise. Fringe, riverine, and interior settings registered elevation changes of -1.30, 0.46, and 1.56 mm y-1, respectively, with the greatest elevation deficit (-3.2 mm y-1) from a fringe zone on Pohnpei and the highest rate of elevation gain (4.1 mm y-1) from an interior zone on Kosrae. Relative to sea-level rise estimates for FSM (0.8-1.8 mm y-1) and assuming a consistent linear trend in these estimates, soil elevations in mangroves on Kosrae and Pohnpei are experiencing between an annual deficit of 4.95 mm and an annual surplus of 3.28 mm. Although natural disturbances are important in mediating elevation gain in some situations, constant allochthonous sediment deposition probably matters most on these Pacific high islands, and is especially helpful in certain hydrogeomorphic zones. Fringe mangrove forests are most susceptible to sea-level rise, such that protection of these outer zones from anthropogenic disturbances (for example, harvesting) may slow the rate at which these zones convert to open water. ?? 2010 GovernmentEmployee: U.S. Geological Survey, National Wetlands Research Center.

Krauss, K. W.; Cahoon, D. R.; Allen, J. A.; Ewel, K. C.; Lynch, J. C.; Cormier, N.

2010-01-01

469

Enhancement of stimulated Raman scattering of weak-gain Raman modes in a pendant drop by dye-lasing gain  

NASA Astrophysics Data System (ADS)

The enhancement of stimulated Raman scattering (SRS) of weak-gain Raman modes in pendant drops is accomplished by overlapping Stokes wavelengths of the Raman modes with the Rhodamine 640 dye-lasing gain region (called the gain-overlap method). The dye concentration and the pumping intensity of frequency-doubled Nd:YAG lasers determine the efficiency of the enhancement. We apply the gain-overlap technique at optimal dye concentration and pump intensity to probe minority species in pendant drops formed by binary mixtures. The limits of detectable concentrations of the minority species, methanol in methanol-ethanol and ethanol in ethanol-water (dye-doped) mixtures, are much less than those in undoped mixtures. The smooth fluorescence-lasing spectral curves emitted from dye-doped pendant drops reduce complications in distinguishing SRS signals from quasi-periodic fluorescence-lasing spectra in microdroplets.

Pu, Xiao-Yun; Yang, Zheng; Lee, Wing-Kee

2004-02-01

470

Weight gain in smokers after quitting cigarettes: meta-analysis  

PubMed Central

Objective To describe weight gain and its variation in smokers who achieve prolonged abstinence for up to 12 months and who quit without treatment or use drugs to assist cessation. Design Meta-analysis. Data sources We searched the Central Register of Controlled Trials (CENTRAL) and trials listed in Cochrane reviews of smoking cessation interventions (nicotine replacement therapy, nicotinic partial agonists, antidepressants, and exercise) for randomised trials of first line treatments (nicotine replacement therapy, bupropion, and varenicline) and exercise that reported weight change. We also searched CENTRAL for trials of interventions for weight gain after cessation. Review methods Trials were included if they recorded weight change from baseline to follow-up in abstinent smokers. We used a random effects inverse variance model to calculate the mean and 95% confidence intervals and the mean of the standard deviation for weight change from baseline to one, two, three, six, and 12 months after quitting. We explored subgroup differences using random effects meta-regression. Results 62 studies were included. In untreated quitters, mean weight gain was 1.12 kg (95% confidence interval 0.76 to 1.47), 2.26 kg (1.98 to 2.54), 2.85 kg (2.42 to 3.28), 4.23 kg (3.69 to 4.77), and 4.67 kg (3.96 to 5.38) at one, two, three, six, and 12 months after quitting, respectively. Using the means and weighted standard deviations, we calculated that at 12 months after cessation, 16%, 37%, 34%, and 13% of untreated quitters lost weight, and gained less than 5 kg, gained 5-10 kg, and gained more than 10 kg, respectively. Estimates of weight gain were similar for people using different pharmacotherapies to support cessation. Estimates were also similar between people especially concerned about weight gain and those not concerned. Conclusion Smoking cessation is associated with a mean increase of 4-5 kg in body weight after 12 months of abstinence, and most weight gain occurs within three months of quitting. Variation in weight change is large, with about 16% of quitters losing weight and 13% gaining more than 10 kg.

2012-01-01

471

Corticotropin-releasing factor-binding protein ligand inhibitor blunts excessive weight gain in genetically obese Zucker rats and rats during nicotine withdrawal  

PubMed Central

Elevation of the neuropeptide corticotropin-releasing factor (CRF) in the brain is associated with a reduction of food intake and body weight gain in normal and obese animals. A protein that binds CRF and the related peptide, urocortin, with high affinity, CRF-binding protein (CRF-BP), may play a role in energy homeostasis by inactivating members of this peptide family in ingestive and metabolic regulatory brain regions. Intracerebroventricular administration in rats of the high-affinity CRF-BP ligand inhibitor, rat/human CRF (6-33), which dissociates CRF or urocortin from CRF-BP and increases endogenous brain levels of “free” CRF or urocortin significantly blunted exaggerated weight gain in Zucker obese subjects and in animals withdrawn from chronic nicotine. Chronic administration of CRF suppressed weight gain nonselectively by 60% in both Zucker obese and lean control rats, whereas CRF-BP ligand inhibitor treatment significantly reduced weight gain in obese subjects, without altering weight gain in lean control subjects. Nicotine abstinent subjects, but not nicotine-naive controls, experienced a 35% appetite suppression and a 25% weight gain reduction following acute and chronic administration, respectively, of CRF-BP ligand inhibitor. In marked contrast to the effects of a CRF-receptor agonist, the CRF-BP ligand inhibitor did not stimulate adrenocorticotropic hormone secretion or elevate heart rate and blood pressure. These results provide support for the hypothesis that the CRF-BP may function within the brain to limit selected actions of CRF and/or urocortin. Furthermore, CRF-BP may represent a novel and functionally selective target for the symptomatic treatment of excessive weight gain associated with obesity of multiple etiology.

Heinrichs, Stephen C.; Lapsansky, Jeannette; Behan, Dominic P.; Chan, Raymond K. W.; Sawchenko, Paul E.; Lorang, Marge; Ling, Nicholas; Vale, Wylie W.; De Souza, Errol B.

1996-01-01

472

New insight into the atmospheric chloromethane budget gained using gained using  

NASA Astrophysics Data System (ADS)

Atmospheric chloromethane (CH3Cl) plays an important role in stratospheric ozone destruction, but many uncertainties still exist regarding strengths of both sources and sinks and the processes leading to formation of this naturally occurring gas. Recent work has identified a novel chemical origin for CH3Cl, which can explain its production in a variety of terrestrial environments: The widespread structural component of plants, pectin, reacts readily with chloride ion to form CH3Cl at both ambient and elevated temperatures (Hamilton et al., 2003). It has been proposed that this abiotic chloride methylation process in terrestrial environments could be responsible for formation of a large proportion of atmospheric CH3Cl. However, more information is required to determine the global importance of this new source and its contribution to the atmospheric CH3Cl budget. A potentially powerful tool in studying the atmospheric CH3Cl budget is the use of stable carbon isotope ratios. In an accompanying paper it is reported that the reaction of CH3Cl with OH radical, the dominant sink for atmospheric CH3Cl, is accompanied by an unexpectedly large fractionation factor (Gola et al., 2005). Another recently published study shows that CH3Cl formed by the abiotic methylation process at ambient temperatures has a unique stable carbon isotope signature, extremely depleted in 1