A Discrete-Event Simulation Approach for Modeling Human Body Glucose Metabolism

This dissertation describes CarbMetSim (Carbohydrate Metabolism Simulator), a discrete-event simulator that tracks the blood glucose level of a person in response to a timed sequence of diet and exercise activities. CarbMetSim implements broader aspects of carbohydrate metabolism in human beings with the objective of capturing the average impact of various diet/exercise activities on the blood glucose level. Key organs (stomach, intestine, portal vein, liver, kidney, muscles, adipose tissue, brain and heart) are implemented to the extent necessary to capture their impact on the production and consumption of glucose. Key metabolic pathways (glucose oxidation, glycolysis and gluconeogenesis) are accounted for by using the published values of the average flux along these pathways in the operation of different organs. CarbMetSim has the ability to model different levels of insulin resistance and insulin production ability. The impact of insulin and insulin resistance on the operation of various organs and pathways is captured in accordance with published research. The protein and lipid metabolism are implemented only to the extent that they affect carbohydrate metabolism

Determinants of workers' remittances: The case of Turkey

Workers ' remittance flows to Turkey have dramatically increased since the 1960s, constituting a significant proportion of imports. The empirical evidence in this paper indicates that black market premium, interest rate differential, inflation rate, growth, home and host country income levels, and periods of military administration in Turkey have significantly affected these flows. Among them, the negatively significant effects of the black market premium, inflation, and a dummy for periods of military administration point at the importance of sound exchange rate policies and economic and political stability in attracting remittance flows. In addition, both investment and consumption-smoothing motives are observed, though the former of which appears more prevalent after the 1980s. © 2005 M.E. Sharpe, Inc. All rights reserved

Strategic Nurse Allocation Policies Under Dynamic Patient Demand

Several studies have shown a strong association between nurse staffing and patient outcomes. When a nursing unit is chronically short-staffed, nurses must maintain an intense pace to ensure that patients receive timely care. Over time this can result in nurse burnout, as well as dissatisfied patients and even medical errors. Improved accuracy in the allocation of nursing staff can mitigate these operational risks and improve patient outcomes. Nursing care is identified as the single biggest factor in both the cost of hospital care and patient satisfaction. Yet, there is widespread dissatisfaction with the current methods of determining nurse staffing levels, including the most common one of using minimum nurse-to-patient ratios. Nurse shortage implications go beyond healthcare quality, extending to health economics as well. In addition, implementation of mandatory nurse-to-patient ratios in some states creates a risk of under- or over-estimating required nurse resources. With this motivation, this dissertation aims to develop methodologies that generate feasible six-week nurse schedules and efficiently assign nurses from various profiles to these schedules while controlling staffing costs and understaffing ratios in the medical unit. First, we develop and test various medium-term staff allocation approaches using mixed-integer optimization and compare their performance with respect to a hypothetical full information scenario. Second, using stochastic integer programming approach, we develop a short-term staffing level adjustment model under a sizable list of patient admission scenarios. We begin by providing an overview of the organization of the dissertation. (Abstract shortened by ProQuest.

ESR dosimetric properties of window glass

The general dosimetric characteristics of commercially window glass were investigated with electron spin resonance (ESR) technique. Irradiated window glasses exhibit a paramagnetic oxygen hole center with an ESR signal at g = 2.0128. The study was carried out on g = 2.0128 signal because of the accuracy of measurements and the possibility of using it as ESR dosimeter. The thermal stability and kinetic features of the ESR signal were studied by annealing the samples at predetermined temperature for predetermined time over the temperature range of 60-150 degrees C. The response of the signal at g = 2.0128 to Co-60 gamma-ray doses ranging from 5 Gy to 20 kGy has been studied. Dose-response was found to be appropriate for dosimetry in the range 5 Gy-20 kGy, taking into account its thermal fading. The other ESR dosimetric parameters of window glass samples, like light effect, dose-rate dependence, reproducibility of measurement, batch uniformity and photon energy dependence, have also been studied in detail. Apart from its non-tissue equivalence character, it showed very good dosimetric properties with visible light independency, good reproducibility, batch uniformity, wide dose-response range (5 Gy 20 kGy), dose-rate independency and independency from photon energy above 100 keV. These features of window glass can open application fields for high-dose measurements and in accident dosimetry in near future. (c) 2005 Elsevier B.V. All rights reserved

Comment surmonter les difficultés des élèves : pistes d’actions

Professorat des lycées et collègesSur la base d’observations, d’expérimentations, d’informations et de réflexions relatives à des difficultés rencontrées limitant l’efficacité de notre enseignement, des pistes d’actions sont envisagées à deux niveaux. L’un est disciplinaire, et repose sur une pédagogie active dans la classe qui permet un partenariat entre l’élève et le professeur. L’autre, global, engage l’établissement à mettre en place des projets qui prennent en compte le contexte socioculturel de l’élève en élargissant la coopération tout en diversifiant les lieux et les activités. Nous aspirons ainsi à rendre l’élève acteur de sa réussite scolaire et personnelle en l’épaulant et l’équipant pour parer à ses difficultés

Detection of gamma irradiated fig seeds by analysing electron spin resonance

Seeds of fig produced in Turkey were studied by electron spin resonance (ESR) technique for detection purposes. Unirradiated fig seeds (control) exhibited a weak ESR singlet at g = 2.0052 +/- 0.0003 (native signal). Irradiation induced at least one additional intense singlet overlapping to the control signal and caused a significant increase in signal intensity without any changes in spectral patterns. Variation of ESR signal intensity of irradiated samples at room temperature with time in a long-term showed that free radicals responsible from the ESR spectrum of fig seeds were not stable but detectable after 80 days. Annealing studies at five different temperatures were used to determine the kinetic behaviour and activation energy of the radiation-induced radicals in fig seeds. A study on microwave saturation characteristics and thermal behaviour of the ESR singlet (g = 2.0052) in irradiated and unirradiated fig seed samples was also carried out by using ESR technique. These preliminary results indicate that microwave saturation characteristics of the ESR signal at room and low temperatures may be useful method to distinguish irradiated fig seeds from unirradiated ones. (c) 2010 Elsevier Ltd. All rights reserved

Study of the thermoluminescence dosimetric properties of window glass

This paper presents the main thermoluminescence (TL) dosimetric characteristics of commercial Turkish transparent window glass. The structure of the glow curves, including the number of peaks, was found to be dose-dependent. A low-temperature glow peak that at 160 degrees C shifts to higher temperatures was also observed with increasing storage time at room temperature. This result suggests that this TL glow peak is actually made up of two or more overlapping peaks. These we have attributed to the glow peaks at lower temperatures, which decay faster than the ones at higher temperatures with storage time. The thermal fading of the window glass sample at room temperature showed a relatively sharp decay of about 60% occurring over a period of 28 days, after which the decay rate is small for a measured period of 250 days. In order to the improve the post-irradiation stability of the glow curve, the glass samples were heated after irradiation. To remove the unstable TL peaks responsible for the initial rapid fading, post-irradiation heating at 160 degrees C for 10 min was found to be the most suitable procedure. The dosimetric characteristics of the post-irradiation heated window glass examined in this study include fading, gamma photon dose-response, reproducibility, batch sensitivity, humidity influence, a dose-rate effect and photon energy response. Dose-response was found to be appropriate for dosimetry in the range 5Gy to 10 kGy. The post-irradiation heating procedure did not affect the main dosimetric characteristics of the window glass samples. The results in this work suggest that the materials could, by using the TL technique, be a suitable candidate for alternative dose measurements in radiation processing, provided that a judicious choice of the post-irradiation heat temperature is made to minimize fading

Electron spin resonance study of gamma-irradiated Anatolian chickpea (Cicer arietinum L.)

In this study, an electron spin resonance (ESR) investigation on gamma-irradiated chickpea cultivated in Turkey is reported in detail. ESR spectra of unirradiated (control) chickpea were composed of an equally spaced sextet originating from the presence of Mn2+ ions and a single weak resonance signal both centered at g = 2.0054 +/- 0.0006. Although irradiation was found to have no effect on the Mn2+ signals, it caused a noteworthy increase in free radical signal intensity of chickpea in the studied dose range of (0.1-4.5 kGy). In addition, the ESR spectrum of irradiated chickpea recorded at low scan range (10 mT) showed that there were more than one radical species, having different spectral features, contributing to the central resonance signal. From this point of view, we focussed on the free radical signal in the present study. The area under the ESR absorption curve which is related to the free radical concentration was determined from the experimental spectra recorded throughout the study, and its variation with microwave power, radiation dose, storage time and temperature was investigated in detail. Free radical concentration was observed to decay very fast within the first 15 days after the irradiation cessation and little thereafter. At the end of the storage period (60 days), the free radical concentration is still higher than that of the control (unirradiated) sample. The decay of free radical concentration at room and high temperatures were described well by the sum of three second-order decay functions representing three different radical species (A, B and C). The activation energies of these radicals, evaluated by Arrhenius analysis, are in the order E-C > E-B > E-A. Simulation calculations have shown that three radical species (A, B and C) of different spectral parameters were found to best explain the experimental values

CarbMetSim: A discrete-event simulator for carbohydrate metabolism in humans.

This paper describes CarbMetSim, a discrete-event simulator that tracks the blood glucose level of a person in response to a timed sequence of diet and exercise activities. CarbMetSim implements broader aspects of carbohydrate metabolism in human beings with the objective of capturing the average impact of various diet/exercise activities on the blood glucose level. Key organs (stomach, intestine, portal vein, liver, kidney, muscles, adipose tissue, brain and heart) are implemented to the extent necessary to capture their impact on the production and consumption of glucose. Key metabolic pathways (glucose oxidation, glycolysis and gluconeogenesis) are accounted for in the operation of different organs. The impact of insulin and insulin resistance on the operation of various organs and pathways is captured in accordance with published research. CarbMetSim provides broad flexibility to configure the insulin production ability, the average flux along various metabolic pathways and the impact of insulin resistance on different aspects of carbohydrate metabolism. The simulator does not yet have a detailed implementation of protein and lipid metabolism. This paper contains a preliminary validation of the simulator's behavior. Significant additional validation is required before the simulator can be considered ready for use by people with Diabetes