Dissociation of CH4 by electron impact: Production of metastable hydrogen and carbon fragments

Metastable fragments produced by electron impact excitation of CH4 have been investigated for incident electron energies from threshold to 300 eV. Only metastable hydrogen and carbon atoms were observed. Onset energies for the production of metastable hydrogen atoms were observed at electron impact energies of 22.0 + or - .5 eV, 25.5 + or - .6 eV, 36.7 + or - .6 eV and 66 + or - 3 eV, and at 26.6 + or - .6 eV for the production of metastable carbon atoms. Most of the fragments appear to have been formed in high-lying Rydberg states. The total metastable hydrogen cross section reaches a maximum value of approximately 1 X 10 to the minus 18th power sq cm at 100 eV. At the same energy, the metastable carbon cross section is 2 x 10 to the minus 19th power sq cm

Discharge Education for Residents: A Study of Trainee Preparedness for Hospital Discharge

BACKGROUND: Safe hospital discharges have become a major focus in the national discussion on transitions of care and care coordination. Education on the hospital discharge process is evolving as the needs of trainees are better understood. PURPOSE: This study is a cross-sectional survey of residents in a Midwestern residency program about their confidence in safely discharging patients from the hospital, including how they have or have not learned to do so. METHODS: An anonymous paper questionnaire was distributed to a convenience sample of interns and residents at a weekly meeting of the residency program. RESULTS: Most residents reported a general confidence in their abilities to safely discharge patients from the hospital; however, further probing revealed that their confidence breaks down when required to competently perform specific tasks of the discharge process such as activity restrictions or facilitation of home care. More than 50% of house staff surveyed responded that their education in many specific aspects of the discharge process are lacking. CONCLUSION: Interdisciplinary care education, and the discharge summary in particular, warrant further scrutiny as a care transition tool and means of teaching safe hospital discharge to trainees. We present a questionnaire that may serve useful as an anonymous tool to gauge residents' educational needs

Chemical Association via Exact Thermodynamic Formulations

It can be fruitful to view two-component physical systems of attractive monomers, A and B, ``chemically'' in terms of a reaction A + B C, where C = AB is an associated pair or complex. We show how to construct free energies in the three-component or chemical picture which, under mass-action equilibration, exactly reproduce any given two-component or ``physical'' thermodynamics. Order-by-order matching conditions and closed-form chemical representations reveal the freedom available to modify the A-C, B-C, and C-C interactions and to adjust the association constant. The theory (in the simpler one-component, i.e., A = B, case) is illustrated by treating a van der Waals fluid.Comment: 15 double-spaced pages (RevTeX), including 1 eps figur

Derivation of Hebb's rule

On the basis of the general form for the energy needed to adapt the connection strengths of a network in which learning takes place, a local learning rule is found for the changes of the weights. This biologically realizable learning rule turns out to comply with Hebb's neuro-physiological postulate, but is not of the form of any of the learning rules proposed in the literature. It is shown that, if a finite set of the same patterns is presented over and over again to the network, the weights of the synapses converge to finite values. Furthermore, it is proved that the final values found in this biologically realizable limit are the same as those found via a mathematical approach to the problem of finding the weights of a partially connected neural network that can store a collection of patterns. The mathematical solution is obtained via a modified version of the so-called method of the pseudo-inverse, and has the inverse of a reduced correlation matrix, rather than the usual correlation matrix, as its basic ingredient. Thus, a biological network might realize the final results of the mathematician by the energetically economic rule for the adaption of the synapses found in this article.Comment: 29 pages, LaTeX, 3 figure

Pipeline column separation flow regimes

A generalized set of pipeline column separation equations is presented describing all conventional types of low-pressure regions. These include water hammer zones, distributed vaporous cavitation, vapor cavities, and shocks (that eliminate distributed vaporous cavitation zones). Numerical methods for solving these equations are then considered, leading to a review of three numerical models of column separation. These include the discrete vapor cavity model, the discrete gas cavity model, and the generalized interface vaporous cavitation model. The generalized interface vaporous cavitation model enables direct tracking of actual column separation phenomena (e.g., discrete cavities, vaporous cavitation zones), and consequently, better insight into the transient event. Numerical results from the three column separation models are compared with results of measurements for a number of flow regimes initiated by a rapid closure of a downstream valve in a sloping pipeline laboratory apparatus. Finally, conclusions are drawn about the accuracy of the modeling approaches. A new classification of column separation (active or passive) is proposed based on whether the maximum pressure in a pipeline following column separation results in a short-duration pressure pulse that exceeds the magnitude of the Joukowsky pressure rise for rapid valve closure.Anton Bergant and Angus R. Simpso

Phase separation in mixtures of colloids and long ideal polymer coils

Colloidal suspensions with free polymer coils which are larger than the colloidal particles are considered. The polymer-colloid interaction is modeled by an extension of the Asakura-Oosawa model. Phase separation occurs into dilute and dense fluid phases of colloidal particles when polymer is added. The critical density of this transition tends to zero as the size of the polymer coils diverges.Comment: 5 pages, 3 figure

Investigating the Avoidability of Hospitalizations of Long Stay Nursing Home Residents: Opportunities for Improvement

Background and Objectives: To examine the relationship between hospital diagnoses associated with hospital transfers of long stay nursing home residents, ratings of avoidability of transfer, and RN-identified quality improvement opportunities. Research Design and Methods: Prospective clinical demonstration project, named OPTIMISTIC, with trained RNs embedded in nursing homes that performed root cause analyses for 1,931 transfers to the hospital between November 2014 and July 2016. OPTIMISTIC RNs also rated whether transfers were avoidable, identified quality improvement opportunities, and recorded hospital diagnoses. Resident characteristics were obtained from Minimum Data Set assessments. Relationships between six hospital diagnoses commonly considered "potentially avoidable" and OPTIMISTIC RN root cause analysis findings were examined. Facilities were participating in the OPTIMISTIC demonstration project designed to reduce hospital transfers during the study period. Results: Twenty-five percent of acute transfers associated with six common diagnoses were considered definitely or probably avoidable by project RNs versus 22% of transfers associated with other diagnoses. The most common quality improvement opportunity identified for transfers rated as avoidable was that the condition could have been managed safely if appropriate resources were available, a factor cited in 45% of transfers associated with any of the six diagnoses. Problems with communication among stakeholders were the most commonly noted area for improvement (48%) for transfers associated with other diagnoses. Many other areas for quality improvement were noted, including earlier detection of change in status and the need for understanding patient preferences or a palliative care plan. Discussion and Implications: Although some nursing home transfers may later be deemed potentially avoidable based on post-transfer hospital diagnosis from Medicare claims data, OPTIMISTIC nurses caring for these residents at time of transfer categorized the majority of these transfers as unavoidable irrespective of the hospital diagnosis. Multiple quality improvement opportunities were identified associated with these hospital transfers, whether the transfer was considered potentially avoidable or unavoidable

Phase transitions in a ferrofluid at magnetic field induced microphase separation

In the presence of a magnetic field applied perpendicular to a thin sample layer, a suspension of magnetic colloidal particles (ferrofluid) can form spatially modulated phases with a characteristic length determined by the competition between dipolar forces and short-range forces opposing density variations. We introduce models for thin-film ferrofluids in which magnetization and particle density are viewed as independent variables and in which the non-magnetic properties of the colloidal particles are described either by a lattice-gas entropy or by the Carnahan-Starling free energy. Our description is particularly well suited to the low-particle density regions studied in many experiments. Within mean-field theory, we find isotropic, hexagonal and stripe phases, separated in general by first-order phase boundaries.Comment: 12 pages, RevTex, to appear in PR