Independent Eigenstates of Angular Momentum in a Quantum N-body System

The global rotational degrees of freedom in the Schr\"{o}dinger equation for an $N$-body system are completely separated from the internal ones. After removing the motion of center of mass, we find a complete set of $(2\ell+1)$ independent base functions with the angular momentum $\ell$. These are homogeneous polynomials in the components of the coordinate vectors and the solutions of the Laplace equation, where the Euler angles do not appear explicitly. Any function with given angular momentum and given parity in the system can be expanded with respect to the base functions, where the coefficients are the functions of the internal variables. With the right choice of the base functions and the internal variables, we explicitly establish the equations for those functions. Only (3N-6) internal variables are involved both in the functions and in the equations. The permutation symmetry of the wave functions for identical particles is discussed.Comment: 24 pages, no figure, one Table, RevTex, Will be published in Phys. Rev. A 64, 0421xx (Oct. 2001

Low-lying spectrum of the Y-string three-quark potential using hyper-spherical coordinates

We calculate the energies of three-quark states with definite permutation symmetry (i.e. of SU(6) multiplets) in the N=0,1,2 shells, confined by the Y-string three-quark potential. The exact Y-string potential consists of one, so-called three-string term, and three angle-dependent two-string terms. Due to this technical complication we treat the problem at three increasingly accurate levels of approximation: 1) the (approximate) three-string potential expanded to first order in trigonometric functions of hyper-spherical angles; 2) the (approximate) three-string potential to all orders in the power expansion in hyper-spherical harmonics, but without taking into account the transition(s) to two-string potentials; 3) the exact minimal-length string potential to all orders in power expansion in hyper-spherical harmonics, and taking into account the transition(s) to two-string potentials. We show the general trend of improvement %convergence of these approximations: The exact non-perturbative corrections to the total energy are of the order of one per cent, as compared with approximation 2), yet the exact energy differences between the $[20,1^{+}], [70,2^{+}], [56,2^{+}], [70,0^{+}]$-plets are shifted to 2:2:0.9, from the Bowler and Tynemouth separation rule 2:2:1, which is obeyed by approximation 2) at the one per cent level. The precise value of the energy separation of the first radial excitation ("Roper") $[56^{\prime},0^{+}]$-plet from the $[70,1^{-}]$-plet depends on the approximation, but does not become negative, i.e. the "Roper" remains heavier than the odd-parity $[70,1^{-}]$-plet in all of our approximations.Comment: 19 pages, 6 figure

Factors associated with FEV1 decline in cystic fibrosis : analysis of the ECFS patient registry

Pulmonary insufficiency is the main cause of death in cystic fibrosis (CF). We analysed forced expiratory volume in 1 s (FEV1) data of 14 732 patients registered in the European Cystic Fibrosis Society Patient Registry (ECFSPR) database in 2007. We used linear and logistic regressions to investigate associations between FEV1 % predicted and clinical outcomes. Body mass index (BMI), chronic infection by Pseudomonas aeruginosa, pancreatic status and CF-related diabetes (CFRD) showed a statistically significant (all p<0.0001) and clinically relevant effect on FEV1 % pred after adjusting for age. Patients with a lower BMI experience a six-fold increased odds ratio (95% CI 5.0-7.3) of having severe lung disease (FEV1 <40% pred) compared to patients with normal BMI. Being chronically infected with P. aeruginosa increases the odds ratio of severe lung disease by 2.4 (95% CI 2.0-2.7), and patients with pancreatic insufficiency experience a 2.0-fold increased odds ratio (95% CI 1.6-2.5) of severe lung disease compared to pancreatic sufficient patients. Patients with CFRD have a 1.8-fold increased odds ratio (95% CI 1.6-2.2) compared to patients not affected. These potential risk factors for pulmonary disease in patients with CF are to some degree preventable or treatable. We emphasise the importance of their early identification through frequent routine tests, the implementation of infection control measures, and a timely initiation of relevant therapies

Human Bocavirus as the Cause of a Life-Threatening Infection▿

Human bocavirus is a recently described respiratory pathogen. A case of a life-threatening human bocavirus infection of a previously healthy pediatric patient is described. An initial clinical presentation of acute bronchiolitis developed into an extremely severe course of disease characterized by pneumothorax, pneumomediastinum, and acute respiratory failure with pronounced air-leak syndrome