Application of the CINGEN program a thermal network data generator

The application of the CINGEN computer program and two of its supporting programs for the evaluation of structural and thermal performance of physical systems was described. The CINGEN program was written and implemented to avoid the duplication effort of performing a finite element approach for structural analysis and a finite differencing technique for thermal analysis, as well as the desire for a geometrical representation of the thermal model to reduce modeling errors. The program simplifies the thermal modeling process by performing all of the capacitance and conductance calculations normally done by the analyst. Each solid element is divided into five tetrahedrons, allowing the total volume to be calculated precisely. A sample problem was illustrated

High-performance light-weight electrodes for hydrogen-oxygen fuel cells

High performance light weight electrodes for hydrogen oxygen fuel cell

Correlation between electric-field-induced phase transition and piezoelectricity in lead zirconate titanate films

We observed that electric field induces phase transition from tetragonal to rhombohedral in polycrystalline morphotropic lead zirconate titanate (PZT) films, as reported in 2011 for bulk PZT. Moreover, we evidenced that this field-induced phase transition is strongly correlated with PZT film piezoelectric properties, that is to say the larger the phase transition, the larger the longitudinal piezoelectric coefficient d 33,eff . Although d 33,eff is already comprised between as 150 to 170 pm/V, our observation suggests that one could obtain larger d 33,eff values, namely 250 pm/V, by optimizing the field-induced phase transition thanks to composition fine tuning

New Results from NA49

We present recent results of the SPS experiment NA49 on production of strange particles and event-by-event fluctuations of mean $p_t$ and of charged particle ratios in central Pb+Pb collisions at various beam energies (40, 80, 158 AGeV) as well as in different collisions at 158 AGeV, going from p+p over light-ion collisions to peripheral and central Pb+Pb.Comment: 5 pages, 6 figures (in eps) talk given at XXXI International Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China URL http://ismd31.ccnu.edu.cn

Development of the Nursing Community Apgar Questionnaire (NCAQ): A Rural Nurse Recruitment and Retention Tool

Introduction: Health professional shortages are a significant issue throughout the USA, particularly in rural communities. Filling nurse vacancies is a costly concern for many critical access hospitals (CAH), which serve as the primary source of health care for rural communities. CAHs and rural communities have strengths and weaknesses that affect their recruitment and retention of rural nurses. The purpose of this study was to develop a tool that rural communities and CAHs can utilize to assess their strengths and weaknesses related to nurse recruitment and retention. Methods: The Nursing Community Apgar Questionnaire (NCAQ) was developed based on an extensive literature review, visits to multiple rural sites, and consultations with rural nurses, rural nurse administrators and content experts. Results: A quantitative interview tool consisting of 50 factors that affect rural nurse recruitment and retention was developed. The tool allows participants to rate each factor in terms of advantage and importance level. The tool also includes three open-ended questions for qualitative analysis. Conclusions: The NCAQ was designed to identify rural communities’ and CAHs’ strengths and challenges related to rural nurse recruitment and retention. The NCAQ will be piloted and a database developed for CAHs to compare their results with those in the database. Furthermore, the NCAQ results may be utilized to prioritize resource allocation and tailor rural nurse recruitment and retention efforts to highlight a community’s strengths. The NCAQ will function as a useful real-time tool for CAHs looking to assess and improve their rural nurse recruitment and retention practices and compare their results with those of their peers. Longitudinal results will allow CAHs and their communities to evaluate their progress over time. As the database grows in size, state, regional, and national results can be compared, trends may be discovered and best practices identified

Phase Separation in Charge-Stabilized Colloidal Suspensions: Influence of Nonlinear Screening

The phase behavior of charge-stabilized colloidal suspensions is modeled by a combination of response theory for electrostatic interparticle interactions and variational theory for free energies. Integrating out degrees of freedom of the microions (counterions, salt ions), the macroion-microion mixture is mapped onto a one-component system governed by effective macroion interactions. Linear response of microions to the electrostatic potential of the macroions results in a screened-Coulomb (Yukawa) effective pair potential and a one-body volume energy, while nonlinear response modifies the effective interactions [A. R. Denton, \PR E {\bf 70}, 031404 (2004)]. The volume energy and effective pair potential are taken as input to a variational free energy, based on thermodynamic perturbation theory. For both linear and first-order nonlinear effective interactions, a coexistence analysis applied to aqueous suspensions of highly charged macroions and monovalent microions yields bulk separation of macroion-rich and macroion-poor phases below a critical salt concentration, in qualitative agreement with predictions of related linearized theories [R. van Roij, M. Dijkstra, and J.-P. Hansen, \PR E {\bf 59}, 2010 (1999); P. B. Warren, \JCP {\bf 112}, 4683 (2000)]. It is concluded that nonlinear screening can modify phase behavior but does not necessarily suppress bulk phase separation of deionized suspensions.Comment: 14 pages of text + 9 figure

Nonlinear Screening and Effective Electrostatic Interactions in Charge-Stabilized Colloidal Suspensions

A nonlinear response theory is developed and applied to electrostatic interactions between spherical macroions, screened by surrounding microions, in charge-stabilized colloidal suspensions. The theory describes leading-order nonlinear response of the microions (counterions, salt ions) to the electrostatic potential of the macroions and predicts microion-induced effective many-body interactions between macroions. A linear response approximation [Phys. Rev. E 62, 3855 (2000)] yields an effective pair potential of screened-Coulomb (Yukawa) form, as well as a one-body volume energy, which contributes to the free energy. Nonlinear response generates effective many-body interactions and essential corrections to both the effective pair potential and the volume energy. By adopting a random-phase approximation (RPA) for the response functions, and thus neglecting microion correlations, practical expressions are derived for the effective pair and triplet potentials and for the volume energy. Nonlinear screening is found to weaken repulsive pair interactions, induce attractive triplet interactions, and modify the volume energy. Numerical results for monovalent microions are in good agreement with available ab initio simulation data and demonstrate that nonlinear effects grow with increasing macroion charge and concentration and with decreasing salt concentration. In the dilute limit of zero macroion concentration, leading-order nonlinear corrections vanish. Finally, it is shown that nonlinear response theory, when combined with the RPA, is formally equivalent to the mean-field Poisson-Boltzmann theory and that the linear response approximation corresponds, within integral-equation theory, to a linearized hypernetted-chain closure.Comment: 30 pages, 8 figures, Phys. Rev. E (in press

Intrinsic and extrinsic x-ray absorption effects in soft x-ray diffraction from the superstructure in magnetite

We studied the (001/2) diffraction peak in the low-temperature phase of magnetite (Fe3O4) using resonant soft x-ray diffraction (RSXD) at the Fe-L2,3 and O-K resonance. We studied both molecular-beam-epitaxy (MBE) grown thin films and in-situ cleaved single crystals. From the comparison we have been able to determine quantitatively the contribution of intrinsic absorption effects, thereby arriving at a consistent result for the (001/2) diffraction peak spectrum. Our data also allow for the identification of extrinsic effects, e.g. for a detailed modeling of the spectra in case a "dead" surface layer is present that is only absorbing photons but does not contribute to the scattering signal.Comment: to appear in Phys. Rev.

Viewing stomata in action: Autonomous in planta imaging of individual stomatal movement links morphology and kinetics

Stomata regulate plant gas exchange with the environment, balancing between water loss and CO2 uptake. Gas exchange dynamics are influenced by traits such as stomatal morphology, size and density, which are commonly investigated using imprints and manual microscopy, methods that are destructive and time consuming. Moreover, these microscopic properties are statically sampled and related to the dynamic ensemble behavior: gas exchange of an entire plant or part of a leaf. Knowledge on how morphology, size and density of stomata influence the movement of individual stomata is limited. We developed a compact microscope system that can measure the kinetics of tens of stomata in vivo simultaneously, with sub-minute time resolution. The system can be deployed in the plant’s growth environment, at minimal impact on leaf microclimate. The characteristics of our microscope and data analyses are described, and we demonstrate its capabilities on Chrysanthemum morifolium with novel insight into individual stomata’s contribution to water-use efficienc