382 research outputs found

    Hyperfine splitting of the dressed hydrogen atom ground state in non-relativistic QED

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    We consider a spin-1/2 electron and a spin-1/2 nucleus interacting with the quantized electromagnetic field in the standard model of non-relativistic QED. For a fixed total momentum sufficiently small, we study the multiplicity of the ground state of the reduced Hamiltonian. We prove that the coupling between the spins of the charged particles and the electromagnetic field splits the degeneracy of the ground state.Comment: 22 page

    The dressed nonrelativistic electron in a magnetic field

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    We consider a nonrelativistic electron interacting with a classical magnetic field pointing along the x3x_{3}-axis and with a quantized electromagnetic field. When the interaction between the electron and photons is turned off, the electronic system is assumed to have a ground state of finite multiplicity. Because of the translation invariance along the x3x_{3}-axis, we consider the reduced Hamiltonian associated with the total momentum along the x3x_{3}-axis and, after introducing an ultraviolet cutoff and an infrared regularization, we prove that the reduced Hamiltonian has a ground state if the coupling constant and the total momentum along the x3x_{3}-axis are sufficiently small. Finally we determine the absolutely continuous spectrum of the reduced Hamiltonian.Comment: typos correction

    Inverse spectral results for Schr\"odinger operators on the unit interval with potentials in L^P spaces

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    We consider the Schr\"odinger operator on [0,1][0,1] with potential in L1L^1. We prove that two potentials already known on [a,1][a,1] (a∈(0,1/2]a\in(0,{1/2}]) and having their difference in LpL^p are equal if the number of their common eigenvalues is sufficiently large. The result here is to write down explicitly this number in terms of pp (and aa) showing the role of pp

    Hyperfine splitting in non-relativistic QED: uniqueness of the dressed hydrogen atom ground state

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    We consider a free hydrogen atom composed of a spin-1/2 nucleus and a spin-1/2 electron in the standard model of non-relativistic QED. We study the Pauli-Fierz Hamiltonian associated with this system at a fixed total momentum. For small enough values of the fine-structure constant, we prove that the ground state is unique. This result reflects the hyperfine structure of the hydrogen atom ground state.Comment: 22 pages, 3 figure

    A GATE-based Monte Carlo simulation of a dual-layer pixelized gadolinium oxyorthosilicate (GSO) detector performance and response for micro PET scanner

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    The purpose of this study was to simulate the GSO detector of a micro PET using GATE simulation platform. The performance and responses of the simulated GSO detector assembly were evaluated by comparing the simulated data to the experimental and XCOM data to validate the simulation platform and procedure. Based on NEMA NU-4 2008 protocols, the performance of GSO detector in terms of sensitivity was simulated and compared to the experimental data. Similarly, the GSO detector response to photons interaction was simulated and compared against the XCOM data for absorbed intensity ratio in the GSO detector and survived intensity ratio in Pb blocks. Results showed that simulated and experimental sensitivities agreed well with R2 of 0.995 and two overlapping bands at 95% confidence. An agreement with R2 of 0.972 and 0.973 as well as with overlapping bands at 95% confidence was obtained in simulated and XCOM data for absorbed and survived intensity ratio in the GSO detector and Pb blocks, respectively. The observed agreements demonstrate the accuracy of the simulation method to mimic the behaviour of the GSO detector. The validated GATE algorithm for micro PET scanner is therefore recommended for simulation and optimisation of collimator design in further studies. Keywords: GATE simulation, Experimental data, XCOM data, GSO detector, micro PET. &nbsp

    The potential for autonomic neuromodulation to reduce perioperative complications and pain: a systematic review and meta-analysis

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    BACKGROUND: Autonomic dysfunction promotes organ injury after major surgery through numerous pathological mechanisms. Vagal withdrawal is a key feature of autonomic dysfunction, and it may increase the severity of pain. We systematically evaluated studies that examined whether vagal neuromodulation can reduce perioperative complications and pain. METHODS: Two independent reviewers searched PubMed, EMBASE, and the Cochrane Register of Controlled Clinical Trials for studies of vagal neuromodulation in humans. Risk of bias was assessed; I2 index quantified heterogeneity. Primary outcomes were organ dysfunction (assessed by measures of cognition, cardiovascular function, and inflammation) and pain. Secondary outcomes were autonomic measures. Standardised mean difference (SMD) using the inverse variance random-effects model with 95% confidence interval (CI) summarised effect sizes for continuous outcomes. RESULTS: From 1258 records, 166 full-text articles were retrieved, of which 31 studies involving patients (n=721) or volunteers (n=679) met the inclusion criteria. Six studies involved interventional cardiology or surgical patients. Indirect stimulation modalities (auricular [n=23] or cervical transcutaneous [n=5]) were most common. Vagal neuromodulation reduced pain (n=10 studies; SMD=2.29 [95% CI, 1.08-3.50]; P=0.0002; I2=97%) and inflammation (n=6 studies; SMD=1.31 [0.45-2.18]; P=0.003; I2=91%), and improved cognition (n=11 studies; SMD=1.74 [0.96-2.52]; P<0.0001; I2=94%) and cardiovascular function (n=6 studies; SMD=3.28 [1.96-4.59]; P<0.00001; I2=96%). Five of six studies demonstrated autonomic changes after vagal neuromodulation by measuring heart rate variability, muscle sympathetic nerve activity, or both. CONCLUSIONS: Indirect vagal neuromodulation improves physiological measures associated with limiting organ dysfunction, although studies are of low quality, are susceptible to bias and lack specific focus on perioperative patients

    Kagera Regional and District Projections

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    This report presents population projections for the period 2003 to 2025 for the Kagera Region and its districts. The projections were made using a Cohort Component Method (Spectrum System), whereby three components responsible for population change, namely: mortality, fertility and migration were projected separately as well as HIV/AIDS prevalence. The projected components were then applied to 2002 midyear base population in order to come up with the desired projections from 2003 to 2025. The report gives mortality, fertility, migration and HIV/AIDS assumptions, which depicts Kagera’s demographic and socio-economic future trends. The results include estimated population by sex in single years and five-year age groups as well as some demographic indicators. Population growth for the period 2003 to 2025 shows an increase in growth rates. The projections show that population growth rate will increase from 3.1 percent in 2003 (with a population of 1,982,612) to 3.7 percent in 2025 (with a population of 4,511,927). Sex Ratio at birth is projected to increase from 96 male births per 100 females in 2003 to 99 male births per 100 females in 2025. Mortality estimates show that Infant Mortality Rate (IMR) is expected to decline for both sexes from 117 deaths per 1,000 live births in 2003 to 72 deaths per 1,000 live births in 2025. Under Five Mortality Rate (U5MR) for both sexes will also decline from 195 deaths per 1,000 live births in 2003 to 113 deaths per 1,000 live births in the year 2025. The mortality projected estimates further show that the life expectancy at birth for females is higher compared to that of males, which is expected. Life expectancy at birth for Kagera will increase from 48 years in 2003 to 55 years in 2025 for both sexes. For male population, life expectancy at birth will increase from 46 years in year 2003 to 54 years in 2025, while for female population the life expectancy at birth will increase from 49 years in 2003 to 56 years in 2025

    Iringa Regional and District Projections.

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    This report presents population projections for the period 2003 to 2025 for Iringa Region and its districts. The projections were made using a Cohort Component Method (Spectrum System), whereby three components responsible for population change, namely: mortality, fertility and migration were projected separately as well as HIV/AIDS prevalence. The projected components were then applied to 2002 midyear base population in order to come up with the desired projections from 2003 to 2025. The report gives mortality, fertility, migration and HIV/AIDS assumptions, and shows Iringa’s demographic and socio-economic future trends. The results include estimated population by sex in single years and five-year age groups as well as some demographic indicators. Population growth for the period 2003 to 2025 shows a decrease in growth rates. The projections show that population growth rate will decrease from 1.6 percent in 2003 (with a population of 1,520,891) to 0.4 percent in 2025 (with a population of 2,019,217). Sex Ratio at birth is projected to increase from 90 male births per 100 females in 2003 to 99 male births per 100 females in 2025. Mortality estimates show that Infant Mortality Rate (IMR) is expected to decline for both sexes from 127 deaths per 1,000 live births in 2003 to 78 deaths per 1,000 live births in 2025. Under Five Mortality Rate (U5MR) for both sexes will also decline from 207 deaths per 1,000 live births in 2003 to 122 deaths per 1,000 live births in the year 2025. The mortality projected estimates further show that the life expectancy at birth for both males and females stands at 45 years in 2003. Life expectancy at birth for Iringa will decline from 45 years in 2003 to 44 years in 2025 for both sexes. For male population, life expectancy at birth will remain at the same level of 45 years in year 2003 and year 2025, while for female population the life expectancy at birth will decline from 45 years in 2003 to 43 years in 2025. On fertility, TFR will decline from 4.9 children per woman in 2003 to 2.6 children per woman in 2025.\u

    Dar es Salaam Regional and District Projections.

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    This report presents population projections for the period 2003 to 2025 for Dar es Salaam Region. The projections were made using a Cohort Component Method (Spectrum System), whereby three components responsible for population change, namely: mortality, fertility and migration were projected separately as well as HIV/AIDS prevalence. The projected components were then applied to 2002 midyear base population in order to come up with the desired projections from 2003 to 2025. The report gives mortality, fertility, migration and HIV/AIDS assumptions, and shows Dar es Salaam’s demographic and socio-economic future trends. The results include estimated population by sex in single years and five-year age groups as well as some demographic indicators. Population growth for the period 2003 to 2025 shows a decrease in growth rates. The projections show that population growth rate will decrease from 1.99 percent in 2003 (with a population of 2,535,594) to 0.27 percent in 2025 (with a population of 3,055,456). Sex Ratio at birth is projected to increase slightly from 102 male per 100 females in 2003 to 103 male per 100 females in 2025. Mortality estimates show that Infant Mortality Rate (IMR) is expected to decline for both sexes from 80 deaths per 1,000 live births in 2003 to 49 deaths per 1,000 live births in 2025. Under Five Mortality Rate (U5MR) for both sexes will also decline from 122 deaths per 1,000 live births in 2003 to 71 deaths per 1,000 live births in the year 2025. As expected, the mortality projected estimates further show that the life expectancy at birth for females is higher compared to that of males. Life expectancy at birth for Dar es Salaam will decline from 55 years in 2003 to 52 years in 2025 for both sexes. For male population, life expectancy at birth will almost remain at 53 years for the whole period. For female population, the life expectancy at birth will decline from 57 years in 2003 to 52 years in 2025. On fertility, TFR will decline from 2.7 children per woman in 2003 to about 2 children per woman in 2025.\u
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