Controllability on infinite-dimensional manifolds

Following the unified approach of A. Kriegl and P.W. Michor (1997) for a treatment of global analysis on a class of locally convex spaces known as convenient, we give a generalization of Rashevsky-Chow's theorem for control systems in regular connected manifolds modelled on convenient (infinite-dimensional) locally convex spaces which are not necessarily normable.Comment: 19 pages, 1 figur

Exact eigenstates of the pairing-force Hamiltonian

The problem of determining the eigenstates of the pairing-force Hamiltonian is reformulated in terms of the eigenstates of a many-boson system with an N-body interaction. The N-body interaction includes the effects of the Pauli principle on the eigenstates of the pairing-force Hamiltonian. Explicit expressions for four types of eigenstates are derived. These four types are the eigenstates of N pairs in one or two multiply degenerate single-particle levels, the one-pair eigenstates and a new restricted class of N-pair eigenstates.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32140/1/0000194.pd

Interatomic potentials for atomistic simulations of the Ti-Al system

Semi-empirical interatomic potentials have been developed for Al, alpha-Ti, and gamma-TiAl within the embedded atomic method (EAM) by fitting to a large database of experimental as well as ab-initio data. The ab-initio calculations were performed by the linear augmented plane wave (LAPW) method within the density functional theory to obtain the equations of state for a number of crystal structures of the Ti-Al system. Some of the calculated LAPW energies were used for fitting the potentials while others for examining their quality. The potentials correctly predict the equilibrium crystal structures of the phases and accurately reproduce their basic lattice properties. The potentials are applied to calculate the energies of point defects, surfaces, planar faults in the equilibrium structures. Unlike earlier EAM potentials for the Ti-Al system, the proposed potentials provide reasonable description of the lattice thermal expansion, demonstrating their usefulness in the molecular dynamics or Monte Carlo studies at high temperatures. The energy along the tetragonal deformation path (Bain transformation) in gamma-TiAl calculated with the EAM potential is in a fairly good agreement with LAPW calculations. Equilibrium point defect concentrations in gamma-TiAl are studied using the EAM potential. It is found that antisite defects strongly dominate over vacancies at all compositions around stoichiometry, indicating that gamm-TiAl is an antisite disorder compound in agreement with experimental data.Comment: 46 pages, 6 figures (Physical Review B, in press

Nontuberculous mycobacteria: I: Multicenter prevalence study in cystic fibrosis

Nontuberculous mycobacteria (NTM) are potential respiratory pathogens in cystic fibrosis (CF). To assess the species-specific prevalence and risk factors for acquisition, we conducted a prospective, cross-sectional study of the prevalence of NTM and clinical features of patients at 21 U.S. centers. Almost 10% of patients with CF who were 10 years or older were included (n = 986). The overall prevalence of NTM in sputum was 13.0% (range by center, 7-24%). Mycobacterium avium complex (72%) and Mycobacterium abscessus (16%) were the most common species. When compared with patients with CF without NTM, culture-positive subjects were older (26 vs. 22 years, p < 0.001), had a higher FEV1 (60 vs. 54%, p 0.01), higher frequency of Staphylococcus aureus (43 vs. 31%, p 0.01), and lower frequency of Pseudomonas aeruginosa (71 vs. 82%, p < 0.01). Molecular typing revealed that almost all patients within each center had unique NTM strains. In summary, NTM are common in patients with CF, but neither person-to-person nor nosocomial acquisition explained the high prevalence. Older age was the most significant predictor for isolation of NTM. The clinical significance of NTM in CF is incompletely defined, but patients with these organisms should be monitored with repeat cultures

Safety and efficacy of diaphragm pacing in patients with respiratory insufficiency due to amyotrophic lateral sclerosis (DiPALS): a multicentre, open-label, randomised controlled trial

Background: Non-invasive ventilation is part of the standard of care for treatment of respiratory failure in patients with amyotrophic lateral sclerosis (ALS). The NeuRx RA/4 Diaphragm Pacing System has received Humanitarian Device Exemption approval from the US Food and Drug Administration for treatment of respiratory failure in patients with ALS. We aimed to establish the safety and efficacy of diaphragm pacing with this system in patients with respiratory muscle weakness due to ALS. Methods: We undertook a multicentre, open-label, randomised controlled trial at seven specialist ALS and respiratory centres in the UK. Eligible participants were aged 18 years or older with laboratory supported probable, clinically probable, or clinically definite ALS; stable riluzole treatment for at least 30 days; and respiratory insufficiency. We randomly assigned participants (1:1), via a centralised web-based randomisation system with minimisation that balanced patients for age, sex, forced vital capacity, and bulbar function, to receive either non-invasive ventilation plus pacing with the NeuRx RA/4 Diaphragm Pacing System or non-invasive ventilation alone. Patients, carers, and outcome assessors were not masked to treatment allocation. The primary outcome was overall survival, defined as the time from randomisation to death from any cause. Analysis was by intention to treat. This trial is registered, ISRCTN number 53817913. Findings: Between Dec 5, 2011, and Dec 18, 2013, we randomly assigned 74 participants to receive either non-invasive ventilation alone (n=37) or non-invasive ventilation plus diaphragm pacing (n=37). On Dec 18, 2013, the Data Monitoring and Ethics Committee (DMEC) recommended suspension of recruitment on the basis of overall survival figures. Randomly assigned participants continued as per the study protocol until June 23, 2014, when the DMEC advised discontinuation of pacing in all patients. Follow-up assessments continued until the planned end of the study in December, 2014. Survival was shorter in the non-invasive ventilation plus pacing group than in the non-invasive ventilation alone group (median 11·0 months [95% CI 8·3-13·6] vs 22·5 months [13·6-not reached]; adjusted hazard ratio 2·27, 95% CI 1·22-4·25; p=0·009). 28 (76%) patients died in the pacing group and 19 (51%) patients died in the non-invasive ventilation alone group. We recorded 162 adverse events (5·9 events per person-year) in the pacing group, of which 46 events were serious, compared with 81 events (2·5 events per person-year) in the non-invasive ventilation alone group, of which 31 events were serious. Interpretation: Addition of diaphragm pacing to standard care with non-invasive ventilation was associated with decreased survival in patients with ALS. Our results suggest that diaphragmatic pacing should not be used as a routine treatment for patients with ALS in respiratory failure