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Fixed Time Interval (fixed + time_interval)
Selected AbstractsNeural-network-based finite-time H, control for extended Markov jump nonlinear systemsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 7 2010Xiaoli Luan Abstract This paper presents a neural-network-based finite-time H, control design technique for a class of extended Markov jump nonlinear systems. The considered stochastic character is described by a Markov process, but with only partially known transition jump rates. The sufficient conditions for the existence of the desired controller are derived in terms of linear matrix inequalities such that the closed-loop system trajectory stays within a prescribed bound in a fixed time interval and has a guaranteed H, noise attenuation performance for all admissible uncertainties and approximation errors of the neural networks. A numerical example is used to illustrate the effectiveness of the developed theoretic results. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effect of count duration on abundance estimates of Black-capped VireosJOURNAL OF FIELD ORNITHOLOGY, Issue 1 2009David A. Cimprich ABSTRACT Distance sampling applied to point count surveys (point transects) has become a common method for estimating the absolute abundance of birds. When conducting point transects, detections of focal species are typically recorded during a fixed time interval. However, count duration has varied among studies and the effect of such variation on the resulting abundance estimates is unclear. My objective was to examine the effect of count duration on abundance estimates of male Black-capped Vireos (Vireo atricapilla). The abundance of these vireos in a 349-ha area in central Texas was estimated using 3-, 5-, and 6-min point transects and results were then compared to actual number present as determined by banding and territory mapping. The 3-min counts provided an estimate that was 26% greater than the actual number of male Vireos present (N= 201), but this number was within the corresponding 95% confidence interval (N= 157,413). Confidence intervals for the 5- and 6-min counts did not include the actual number of vireos present. The shortest count duration may have provided the most accurate abundance estimate because male Black-capped Vireos are typically active, sing intermittently, and sometimes move tens of meters between songs. Thus, shorter-duration counts may also yield the most accurate abundance estimates for other species that exhibit similar behavior. However, because behavior varies among species, I recommend that investigators collect preliminary data to establish an appropriate count duration when accurate estimates of absolute, rather than relative, abundance are important. RESUMEN El muestreo a distancia aplicado a conteos de punto (transectos de punto) se ha convertido en un método común para estimar la abundancia absoluta de aves. Cuando se conducen conteos de punto, la detección de especies focales, típicamente, se lleva a cabo durante un periodo de tiempo definido. Sin embargo, la duración de tiempo del conteo, varía en diferentes estudios y el efecto de dicha variación, en los estimados de abundancia, no está definido. Mi objetivo fue examinar el efecto del periodo de tiempo usado en los conteos utilizando como objeto de estudio a Vireo atricapilla. La abundancia de dichas aves en 349 ha en la parte central de Texas, fue estimada utilizando periodos de 3, 5 y 6 minutos en cada punto del transecto. Los resultados fueron comparados a números obtenidos con recobro de animales anillados y mapas de territorios. Los conteos de 3 minutos dieron como resultado un 26% más alto que el número de machos presentes en la localidad (N= 201). Pero dichos resultados estuvieron dentro del intérvalo de confiabilidad de 95% (N= 157,413). Intérvalos de 5 y 6 minutos no estimaron adecuadamente el número de vireos presentes. El conteo más corto (3 minutos) suministró los números más exactos, aparentemente porque el ave estudiada, típicamente está activa, canta de forma intermitente y en ocasiones se mueve de lugar (decenas de metros) entre canciones. Por lo tanto los conteos más cortos deben de proveer los estimados de abundancia más precisos para otras especies de aves con hábitos similares. Sin embargo, dado el caso de que la conducta entre especies varía, recomendamos a otros investigadores, que tomen datos preliminares para establecer la duración más apropiada de conteos, cuando se necesiten estimados de absoluta exactitud, en vez de estimados relativos de abundancia. [source] Optimal control of innate immune responseOPTIMAL CONTROL APPLICATIONS AND METHODS, Issue 2 2002Robert F. Stengel Abstract Treatment of a pathogenic disease process is interpreted as the optimal control of a dynamic system. Evolution of the disease is characterized by a non-linear, fourth-order ordinary differential equation that describes concentrations of pathogens, plasma cells, and antibodies, as well as a numerical indication of patient health. Without control, the dynamic model evidences sub-clinical or clinical decay, chronic stabilization, or unrestrained lethal growth of the pathogen, depending on the initial conditions for the infection. The dynamic equations are controlled by therapeutic agents that affect the rate of change of system variables. Control histories that minimize a quadratic cost function are generated by numerical optimization over a fixed time interval, given otherwise lethal initial conditions. Tradeoffs between cost function weighting of pathogens, organ health, and use of therapeutics are evaluated. Optimal control solutions that defeat the pathogen and preserve organ health are demonstrated for four different approaches to therapy. It is shown that control theory can point the way toward new protocols for treatment and remediation of human diseases. Copyright © 2002 John Wiley & Sons, Ltd. [source] Neurological recovery in obstetric brachial plexus injuries: an historical cohort studyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2004Agnes F Hoeksma MD An historical cohort study was conducted to investigate the rate and extent of neurological recovery in obstetric brachial plexus injury (OBPI) and to identify possible prognostic factors in a cohort of children with OBPI from birth to 7 years. All children (n=56; 31 females, 25 males) with OBPI were evaluated at fixed time intervals by one examiner. They underwent a final neurological examination at a mean age of 3 years 10 months (range 1 to 7 years). Neurological outcome was not as favourable as is often reported: complete neurological recovery occurred in 37 out of 56 children (66%). In half of these there was delayed recovery, in which case complete neurological recovery was assessed from 1.5 to 16 months of age (median age 6.5 months, SD 4.2 months). External rotation and supination were the last to recover and recovered the least. Although biceps function at three months was considered to be the best indicator for operative treatment, external rotation and supination were found to be better in predicting eventual complete recovery. Initial symptoms directly post partum were not found to be prognostic. Functional outcome was mainly reported to be good. [source] ESSENTIAL OIL AND OLEORESINS OF CINNAMOMUM TAMALA (TEJPAT) AS NATURAL FOOD PRESERVATIVES FOR PINEAPPLE FRUIT JUICEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 5 2008I.P.S. KAPOOR ABSTRACT The essential oil and oleoresins (methanol, ethanol, isooctane and CCl4) from tejpat have been used as a natural food preservative for pineapple juice. The stored samples were studied for pH, total and reducing sugars, ascorbic acid, peroxide value, titrable acidity and microbiological count at fixed time intervals of 7 days. Significant changes were observed during the storage period. The essential oil showed better preservative effect than the oleoresins did. PRACTICAL APPLICATIONS Essential oils and oleoresins derived from spices are considered luxurious items because of their uses in aromatherapy, confectionary, beverages and pharmaceutical industries. Moreover, they also possess antioxidant and antimicrobial efficiency. Essential oil and oleoresins extracted from tejpat are used in the preservation of pineapple juice, which is better and safer than synthetic conservers. This characteristic is of great interest for the food industries. [source] Cocaine and Ethanol: Combined Effects on Coronary Artery Blood Flow and Myocardial Function in DogsACADEMIC EMERGENCY MEDICINE, Issue 7 2009Lance D. Wilson MD Abstract Objectives:, In combination, cocaine and ethanol are more cardiotoxic than is either substance alone. These substances together constitute a drug abuse combination that commonly results in fatality. Previously the authors have demonstrated that cardiotoxicity of cocaine and ethanol is in part due to synergistic myocardial-depressant effects. However, it remains unclear whether this myocardial depression is associated with concomitant adverse effects on coronary blood flow in relation to these substances. The aim of this study was to investigate combined effects of cocaine and ethanol on myocardial blood flow, in relation to indices of myocardial function. Methods:, Anesthetized dogs were instrumented for hemodynamic monitoring with Doppler flow probes placed on the circumflex and left anterior descending (LAD) coronary arteries. Dogs were randomized to three groups (each n = 6): ethanol (E, 1.5 g/kg followed by placebo), cocaine (C, placebo followed by cocaine, 7.5 mg/kg IV), or cocaine plus ethanol (C + E). All measurements were made at control, after placebo or ethanol, and then at fixed time intervals after cocaine or placebo bolus over 3 hours. Results:, In both the C + E and the C groups, circumflex blood flow (CBF) decreased by 71% (95% confidence interval [CI] = 56% to 85%) and 57% (95% CI = 43% to 72%, both p < 0.04 vs. baseline) immediately after cocaine bolus. This was associated with transient depression of cardiac output, myocardial contractile function, and rate-pressure product (RPP), all indices of myocardial oxygen demand. A subsequent rebound increase of coronary sinus blood flow (CSBF) of 56% (95% CI = 26% to 137%, p < 0.03) compared to baseline occurred only in the C group and was associated with increases of myocardial contractile function and RPP. In the C + E group, 2 hours after drug administration, there was a decrease in CSBF of 49% (95% CI = 32% to 67%; p < 0.01) compared to baseline, which was associated with concomitant numerical decreases of the indices of myocardial oxygen demand and accumulation of cocaethylene. Conclusions:, Acute decreases in myocardial flow secondary to cocaine, and cocaine and ethanol in combination, were similar and temporally associated with cocaine's direct myocardial-depressant effects. Rebound increases in myocardial function and blood flow due to cocaine were attenuated by ethanol. Delayed myocardial depression and decreases in myocardial blood flow were observed only with coadministration of cocaine and ethanol. [source] | |||||||||||||