178,093 research outputs found
Effect of phasic contractions and tone of the proximal stomach on triggering of transient lower esophageal sphincter relaxation
No full textWe hypothesized that transient lower esophageal sphincter relaxation (TLESR) is triggered by a discrete motor event, i.e., a phasic contraction or a tonic change of the proximal stomach. The combined esophageal manometry-gastric barostat tracings obtained from 11 healthy subjects during 2-hr continuous isobaric gastric distension were reviewed. Volume waves, i.e., phasic contractions, were analyzed in the 1 and 5 min before onset of each TLESR and in corresponding control periods. Intrabag volume, i.e., proximal gastric tone, was also measured in the 5-min periods. The number of volume waves was similar in the 1- and 5-min pre-TLESR and control periods (0 [0-1], median [IQ range], vs 0 [0-1] and 4 [0.8-5] vs 3 [2-4], respectively], and so were their amplitude, duration, and frequency distribution. Five-minute intrabag volume was also similar (529 ± 77 [mean ± SE] vs 532 ± 74 ml). Our observations suggest that TLESR is not triggered by a preceding phasic contraction or by a different tone of the proximal stomach
Is transient lower esophageal sphincter relaxation triggered by phasic contractions or tonic changes of the proximal stomach?
No full textEffect of prolonged gastric distension on motor function of LES and of proximal stomach
No full textGastric distension is a potent stimulus of transient lower esophageal sphincter (LES) relaxation. To investigate the time effect of prolonged gastric distension on the rate of transient LES relaxations, LES pressure, and the motor and sensory functions of the proximal stomach, we performed a continuous isobaric distension of the proximal stomach at the 75% threshold pressure for discomfort for 2 h in seven healthy subjects. A multilumen assembly incorporating a sleeve and an electronic barostat was used. The rate of transient LES relaxations (n/30 min) was constant during the first hour [4.1 ± 1.2 (0-30 min) and 5.4 ± 1.1 (30-60 min)] but markedly decreased (P < 0.05) in the second hour [2.1 ± 0.5 (60-90 min) and 2.3 ± 0.9 (90-120 min)], whereas LES pressure, baseline volume and volume waves within the gastric bag, hunger, and fullness did not change throughout the experiment. It is concluded that the rate of transient LES relaxations decreases with time during prolonged gastric distension, thus suggesting that this type of stimulus should not be used in sequential experimental conditions
La carta idrogeologica dell'Italia meridonale. Metodi ed analisi territoriali per l'identificazione e la caratterizzazione dei corpi idrici sotterranei (Direttiva 2000/60/CE)
No full textNel presente lavoro è illustrata la sintesi dei risultati di uno studio sulle risorse idriche sotterranee dell’Italia Meridionale (Allocca et alii, 2007), sviluppato nell’ambito del programma INTERREG IIC e finanziato dalla CEE. Le analisi condotte sono state finalizzate a ricostruire un quadro sintetico, ma dettagliato, dello stato delle conoscenze delle risorse idriche sotterranee dell’Italia meridionale continentale e della sua attuale utilizzazione. I principali prodotti interpretativi conseguiti sono: 1) carta idrogeologica, alla scala 1:250.000, rappresentativa di tutte le unità/strutture idrogeologiche che, per estensione e tipologia, hanno rilevanza a livello regionale; 2) note illustrative che sintetizzano lo stato delle conoscenze per ciascuna unità/struttura idrogeologica. I metodi di analisi e i risultati ottenuti rappresentano la base conoscitiva attualmente richiesta dalla Direttiva 2000/60/CE, agli Stati Membri, riguardante l’identificazione e la caratterizzazione idrogeologica dei corpi idrici sotterranei, che abbiamo considerato non come volumi di acque sotterranee (sensu Direttiva 2000/60/CE), bensì come corpi geologici acquiferi (Meinzer, 1923)
Assessing the impact of seasonal rainfall anomalies on catchment-scale water balance components.
No full textAlthough water balance components at the catchment scale are strongly related to annual rainfall, the availability of water resources in Mediterranean catchments also depends on rainfall seasonality. Observed seasonal anomalies in historical records are fairly episodic, but an increase in their frequency might exacerbate water deficit or water excess if the rainy season shortens or extends its duration, e.g., due to climate change. This study evaluates the sensitivity of water yield, evapotranspiration, and groundwater recharge to changes in rainfall seasonality by using the Soil Water Assessment Tool (SWAT) model applied to the upper Alento River catchment (UARC) in southern Italy, where a long time series of daily rainfall is available from 1920 to 2018. We compare two distinct approaches: (i) a “static” approach, where three seasonal features (namely rainy, dry, and transition fixed-duration 4-month seasons) are identified through the standardized precipitation index (SPI) and (ii) a “dynamic” approach based on a stochastic framework, where the duration of two seasons (rainy and dry seasons) varies from year to year according to a probability distribution. Seasonal anomalies occur when the transition season is replaced by the rainy or dry season in the first approach and when season duration occurs in the tails of its normal distribution in the second approach. Results are presented within a probabilistic framework. We also show that the Budyko curve is sensitive to the rainfall seasonality regime in UARC by questioning the implicit assumption of a temporal steady state between annual average dryness and the evaporative index. Although the duration of the rainy season does not exert a major control on water balance, we were able to identify season-dependent regression equations linking water yield to the dryness index in the rainy season
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Higher-order Laguerre-Gauss interferometry for gravitational-wave detectors with in situ mirror defects compensation HIGHER-ORDER LAGUERRE-GAUSS INTERFEROMETRY ... A. ALLOCCA et al
No full textThe use of higher-order Laguerre-Gauss modes has been proposed to decrease the influence of thermal noise in future generation gravitational-wave interferometric detectors. The main obstacle for their implementation is the degeneracy of modes with same order, which highly increases the requirements on the mirror defects, beyond the state-of-the-art polishing and coating techniques. In order to increase the mirror surface quality, it is also possible to act in situ, using a thermal source, sent on the mirrors after a proper shaping. In this paper we present the results obtained on a tabletop Fabry-Pérot Michelson interferometer illuminated with a LG3,3 mode. We show how an incoherent light source can reduce the astigmatism of one of the mirrors, increasing the quality of the beam in one of the Fabry-Pérot cavities and then the contrast of the interferometer. The system has the potential to reduce more complex defects and also to be used in future gravitational-wave detectors using conventional Gaussian beams
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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