Evolution of Relativistic Effects in the Photoionization of Free and Confined Heavy Atoms

At high enough Z relativistic effects become important contributors to even the qualitative nature of atomic properties. This is likely to be true for confined atoms as well. To explore extent of relativistic effects in the photoionization of both free and confined heavy atoms, a theoretical study of the outer subshells of mercury (Z= 80), radon (Z=86), radium (Z=88), and nobelium (Z=102) have been performed using the relativistic random phase approximation (RRPA) methodology in both the free and confined cases. The effects of the C60 potential modeled by a static spherical well are reasonable in the energy region well above the C60 plasmons. In order to determine which features in the photoionization cross section are due to relativistic effects, calculations using the (nonrelativistic) random phase approximation with exchange method (RPAE) are performed for comparison. It is found that relativistic interactions shift and split the nonrelativistic thresholds very considerably, and these changes in thresholds translate into very significant alterations to the nonrelativistic cross section. Relativity also alter the wave functions, contracting the s and p orbital significantly for example. These dynamic changes have considerable effects on the relativistic cross sections

The Influence of Medicare Home Health Payment Incentives: Does Payer Source Matter?

During the late 1990s, an interim payment system (IPS) was instituted to constrain Medicare home health care expenditures. Previous research has largely focused on the implications of the IPS for Medicare patients, but our study broadens the analysis to consider patients with other payer sources. Using the National Home and Hospice Care Survey, we found similar effects of the IPS across payer types. Specifically, the IPS was associated with a decrease in access to care for the sickest patients, less agency assistance with activities of daily living, and shorter length-of-use. However, these changes did not translate into worse discharge outcomes.Medicare, health, incentives

Relativistic calculations of angular dependent photoemission time delay

Angular dependence of photoemission time delay for the valence $np_{3/2}$ and $np_{1/2}$ subshells of Ar, Kr and Xe is studied in the dipole relativistic random phase approximation. Strong angular anisotropy of the time delay is reproduced near respective Cooper minima while the spin-orbit splitting affects the time delay near threshold

A systematic review of mobility instruments and their measurement properties for older acute medical patients

<p>Abstract</p> <p>Background</p> <p>Independent mobility is a key factor in determining readiness for discharge for older patients following acute hospitalisation and has also been identified as a predictor of many important outcomes for this patient group. This review aimed to identify a physical performance instrument that is not disease specific that has the properties required to accurately measure and monitor the mobility of older medical patients in the acute hospital setting.</p> <p>Methods</p> <p>Databases initially searched were Medline, Cinahl, Embase, Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials without language restriction or limits on year of publication until July 2005. After analysis of this yield, a second step was the systematic search of Medline, Cinahl and Embase until August 2005 for evidence of the clinical utility of each potentially suitable instrument. Reports were included in this review if instruments described had face validity for measuring from bed bound to independent levels of ambulation, the items were suitable for application in an acute hospital setting and the instrument required observation (rather than self-report) of physical performance. Evidence of the clinical utility of each potentially suitable instrument was considered if data on measurement properties were reported.</p> <p>Results</p> <p>Three instruments, the Elderly Mobility Scale (EMS), Hierarchical Assessment of Balance and Mobility (HABAM) and the Physical Performance Mobility Examination (PPME) were identified as potentially relevant. Clinimetric evaluation indicated that the HABAM has the most desirable properties of these three instruments. However, the HABAM has the limitation of a ceiling effect in an older acute medical patient population and reliability and minimally clinically important difference (MCID) estimates have not been reported for the Rasch refined HABAM. These limitations support the proposal that a new mobility instrument is required for older acute medical patients.</p> <p>Conclusion</p> <p>No existing instrument has the properties required to accurately measure and monitor mobility of older acute medical patients.</p

Identification of a rhythmic firing pattern in the enteric nervous system that generates rhythmic electrical activity in smooth muscle

The enteric nervous system (ENS) contains millions of neurons essential for organization of motor behavior of the intestine. It is well established that the large intestine requires ENS activity to drive propulsive motor behaviors. However, the firing pattern of the ENS underlying propagating neurogenic contractions of the large intestine remains unknown. To identify this, we used high-resolution neuronal imaging with electrophysiology from neighboring smooth muscle. Myoelectric activity underlying propagating neurogenic contractions along murine large intestine [also referred to as colonic migrating motor complexes, (CMMCs)] consisted of prolonged bursts of rhythmic depolarizations at a frequency of ∼2 Hz. Temporal coordination of this activity in the smooth muscle over large spatial fields (∼7 mm, longitudinally) was dependent on the ENS. During quiescent periods between neurogenic contractions, recordings from large populations of enteric neurons, in mice of either sex, revealed ongoing activity. The onset of neurogenic contractions was characterized by the emergence of temporally synchronized activity across large populations of excitatory and inhibitory neurons. This neuronal firing pattern was rhythmic and temporally synchronized across large numbers of ganglia at ∼2 Hz. ENS activation preceded smooth muscle depolarization, indicating rhythmic depolarizations in smooth muscle were controlled by firing of enteric neurons. The cyclical emergence of temporally coordinated firing of large populations of enteric neurons represents a unique neural motor pattern outside the CNS. This is the first direct observation of rhythmic firing in the ENS underlying rhythmic electrical depolarizations in smooth muscle. The pattern of neuronal activity we identified underlies the generation of CMMCs

The Unreasonable Effectiveness of Contact Tracing on Networks with Cliques

Contact tracing, the practice of isolating individuals who have been in contact with infected individuals, is an effective and practical way of containing disease spread. Here, we show that this strategy is particularly effective in the presence of social groups: Once the disease enters a group, contact tracing not only cuts direct infection paths but can also pre-emptively quarantine group members such that it will cut indirect spreading routes. We show these results by using a deliberately stylized model that allows us to isolate the effect of contact tracing within the clique structure of the network where the contagion is spreading. This will enable us to derive mean-field approximations and epidemic thresholds to demonstrate the efficiency of contact tracing in social networks with small groups. This analysis shows that contact tracing in networks with groups is more efficient the larger the groups are. We show how these results can be understood by approximating the combination of disease spreading and contact tracing with a complex contagion process where every failed infection attempt will lead to a lower infection probability in the next attempts. Our results illustrate how contract tracing in real-world settings can be more efficient than predicted by models that treat the system as fully mixed or the network structure as locally tree-like.Comment: 15 pages, 13 figures, 4 table