The dressed nonrelativistic electron in a magnetic field

We consider a nonrelativistic electron interacting with a classical magnetic field pointing along the $x_{3}$-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 $x_{3}$-axis, we consider the reduced Hamiltonian associated with the total momentum along the $x_{3}$-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 $x_{3}$-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

We consider the Schr\"odinger operator on $[0,1]$ with potential in $L^1$. We prove that two potentials already known on $[a,1]$ ($a\in(0,{1/2}]$) and having their difference in $L^p$ 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 $p$ (and $a$) showing the role of $p$

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

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

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

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

Health and (other) Asset Holdings

The empirical literature on the asset allocation and medical expenditures of U.S. households consistently shows that risky portfolio shares are increasing in both wealth and health whereas health investment shares are decreasing in these same variables. Despite this evidence, most of the existing models treat financial and health-related choices separately. This paper bridges this gap by proposing a tractable framework for the joint determination of optimal consumption, portfolio and health investments. We solve for the optimal rules in closed form and show that the model can theoretically reproduce the empirical facts. Capitalizing on this closed-form solution, we perform a structural estimation of the model on HRS data. Our parameter estimates are reasonable and confirm the relevance of all the main characteristics of the model

A Structural Analysis of the Health Expenditures and Portfolio Choices of Retired Agents

Richer and healthier agents tend to hold riskier portfolios and spend proportionally less on health expenditures. Potential explanations include health and wealth effects on preferences, expected longevity or disposable total wealth. Using HRS data, we perform a structural estimation of a dynamic model of consumption, portfolio and health expenditure choices with recursive utility, as well as health-dependent income and mortality risk. Our estimates of the deep parameters highlight the importance of health capital, mortality risk control, convex health and mortality adjustment costs and binding liquidity constraints to rationalize the stylized facts. They also provide new perspectives on expected longevity and on the values of life and health

Non-traumatic chest pain in patients presenting to an urban emergency Department in sub Saharan Africa: a prospective cohort study in Tanzania.

BACKGROUND:Non-traumatic chest pain (NTCP) is a common reason for emergency department (ED) attendance in high-income countries, with the primary concern focused on life threatening cardiovascular diseases. There is general lack of data on aetiologies, diagnosis and management of NTPC in Sub Sahara African (SSA) countries. We aimed to describe evaluation, diagnosis and outcomes of adult patients presenting with NTCP to an urban ED in Tanzania. METHOD:This was a prospective observational cohort study of consecutive adult (≥18 years) patients presenting with non-traumatic chest pain to the Emergency Medicine Department (EMD) of Muhimbili National Hospital (MNH) in Dar es salaam from September 2017 to April 2018. Structured case report form was used to collected demographics, clinical presentation, investigations, diagnosis, and EMD disposition and in hospital mortality. We determined frequency of NTCP among our patients, aetiologies, 24-h and 7-day in-hospital mortality, and predictors for mortality. RESULTS:We screened 29,495 adults attending EMD-MNH during the study and 389 (1.3%) presented with NTCP of these, 349 (90%) were enrolled. The median age was 45 (IQR 29-60) years and 177 (50.7%) were female. Overall, 69.1% patients received electrocardiography (ECG) in the EMD and 34.1% had a troponin test. Heart failure and pulmonary tuberculosis (PTB) were the leading hospital diagnoses (12.6% each), followed by chronic kidney disease (10%) and acute coronary syndrome (ACS) (9.6%). Total of 167 (48%) patients were admitted, and the 24-h and 7-day in-hospital mortality were 5 (3%) and 16 (9.6%) respectively. Univariate risk factors for mortality were a Glasgow Coma Scale of < 15 [RR = 3.4 (95%CI 3.2-23)], Acute Coronary Syndrome [RR = 5.7 (95% CI 1.7-11.8) and Troponin > 0.04 ng/ml [RR 2.9 (95%CI 1.2-7.3)]. Features distinguishing cardiovascular from other causes were: bradycardia [RR = 2.6 (95%CI 2.1-3.2)], heart beat awareness [RR = 2.3 (95%CI 1.7-3.2)] and history of diabetic mellitus [RR = 2.2 (95% CI 1.6-3.0)]. CONCLUSION:In this ED of SSA country, heart failure and pulmonary tuberculosis were the leading causes of NCTP, and ACS was present in 9.6%. NTCP in this setting carries high mortality, and ACS was the leading risk factor for death. ED providers in SSA must increasingly consider cardiovascular causes of NTCP

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

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

Delivering new technologies to the Tanzanian sweetpotato crop through its informal seed system

The concept of integrated seed sector development (ISSD) for sweetpotato was tested in Shinyanga and Meatu districts of the Lake Zone of Tanzania. Agricultural Research Institute (ARI)–Ukiriguru documented the informal system. It comprised male and female vine multipliers with land close to water sources growing sweetpotato during the dry season. They sold vines during the rainy season, with male multipliers and those with larger crops selling more. The average multiplier supplied approximately 50 farmers who commonly travelled 20 km, each buying approximately 1–2 bundles of vine and provided an entry point for disseminating technologies. ARI–Ukiriguru organized demonstrations of rapid multiplication, inorganic and organic fertilizers and new cultivars on multipliers’ land. Fertilizer could economically more than double vine yields with huge potential benefits for an area where production is constrained by planting material; some multipliers immediately began using it. Multipliers took rapid multiplication and new cultivars to their home gardens for further experimentation, seeming likely to adopt especially the cultivar NASPOT 1. A strategy of growing large quantities of irrigated sweetpotato in Misungwi and selling the vines long-distance in Shinyanga, a marketing strategy derived from Uganda, was also adopted. These successes confirm the value of formal-informal seed sector interactions in ISSD