Mapping the X-Ray Emission Region in a Laser-Plasma Accelerator

The x-ray emission in laser-plasma accelerators can be a powerful tool to understand the physics of relativistic laser-plasma interaction. It is shown here that the mapping of betatron x-ray radiation can be obtained from the x-ray beam profile when an aperture mask is positioned just beyond the end of the emission region. The influence of the plasma density on the position and the longitudinal profile of the x-ray emission is investigated and compared to particle-in-cell simulations. The measurement of the x-ray emission position and length provides insight on the dynamics of the interaction, including the electron self-injection region, possible multiple injection, and the role of the electron beam driven wakefield.Comment: 5 pages, 4 figure

p-type Bi2Se3 for topological insulator and low temperature thermoelectric applications

The growth and elementary properties of p-type Bi2Se3 single crystals are reported. Based on a hypothesis about the defect chemistry of Bi2Se3, the p-type behavior has been induced through low level substitutions (1 percent or less) of Ca for Bi. Scanning tunneling microscopy is employed to image the defects and establish their charge. Tunneling and angle resolved photoemission spectra show that the Fermi level has been lowered into the valence band by about 400 meV in Bi1.98Ca0.02Se3 relative to the n-type material. p-type single crystals with ab plane Seebeck coefficients of +180 microVK-1 at room temperature are reported. These crystals show a giant anomalous peak in the Seebeck coefficient at low temperatures, reaching +120 microVK-1 at 7 K, giving them a high thermoelectric power factor at low temperatures. In addition to its interesting thermoelectric properties, p-type Bi2Se3 is of substantial interest for studies of technologies and phenomena proposed for topological insulators.Comment: v2: STM characterization of n and p type Bi2Se3 is adde

The development of ferromagnetism in the doped topological insulator Bi2-xMnxTe3

The development of ferromagnetism in Mn-doped Bi2Te3 is characterized through measurements on a series of single crystals with different Mn content. Scanning tunneling microscopy analysis shows that the Mn substitutes on the Bi sites, forming compounds of the type Bi2-xMnxTe3, and that the Mn substitutions are randomly distributed, not clustered. Mn doping first gives rise to local magnetic moments with Curie-like behavior, but by the compositions Bi1.96Mn0.04Te3 and Bi1.91Mn0.09Te3 a second order ferromagnetic transition is observed, with Tc ~ 9-12 K. The easy axis of magnetization in the ferromagnetic phase is perpendicular to the Bi2Te3 basal plane. Thermoelectric power and Hall effect measurements show that the Mn-doped Bi2Te3 crystals are p-type. Angle resolved photoemission spectroscopy measurements show that the topological surface states that are present in pristine Bi2Te3 are also present in ferromagnetic Mn-doped Bi2-xMnxTe3, and that the dispersion relations of the surface states are changed in a subtle fashion

Thermoelectric transport in Bi2Te3/Sb2Te3\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3 superlattices

The thermoelectric transport properties of $\text{Bi}_2\text{Te}_3/\text{Sb}_2\text{Te}_3$superlattices are analyzed on the basis of first-principles calculations and semi-classical Boltzmann theory. The anisotropy of the thermoelectric transport under electron and hole-doping was studied in detail for different superlattice periods at changing temperature and charge carrier concentrations. A clear preference for thermoelectric transport under hole-doping, as well as for the in-plane transport direction was found for all superlattice periods. At hole-doping the electrical transport anisotropies remain bulk-like for all investigated systems, while under electron-doping quantum confinement leads to strong suppression of the cross-plane thermoelectric transport at several superlattice periods. In addition, insights on the Lorenz function, the electronic contribution to the thermal conductivity and the resulting figure of merit are given

Organizational configuration of hospitals succeeding in attracting and retaining nurses

Organizational configuration of hospitals succeeding in attracting and retaining nurses. This paper contrasts structural and managerial characteristics of low- and high-turnover hospitals, and describes the organizational configuration of attractive hospitals. In countries facing nurse shortages and turnover, some hospitals succeed in recruiting and retaining nurses. In Magnet Hospitals, managerial practices and environmental characteristics increase nurses\u2019 job satisfaction and their commitment to the organization, which in turn decreases nurse turnover. Such an approach suggests that organizations are best understood as clusters of interconnected structures and practices, i.e. organizational configurations rather than entities whose components can be understood in isolation. From a sample of 12 hospitals whose nurse turnover was studied for 1 year, structural and organizational features of hospitals in the first and fourth quartiles, i.e. attractive (turnover11\uc68%) were contrasted. A questionnaire, including perceptions of health-related factors, job demands, stressors, work schedules, organizational climate, and work adjustments antecedent to turnover, was received from 401 nurses working in attractive hospitals (response rate - 53\uc68%) and 774 nurses in conventional hospitals (response rate \ubc 54\uc65%). Structural characteristics did not differentiate attractive and conventional hospitals, but employee perceptions towards the organization differed strikingly. Differences were observed for risk exposure, emotional demands, role ambiguity and conflicts, work-family conflicts, effort-reward imbalance and the meaning of work, all in favour of attractive hospitals (P < 0.01). Relationships with nursing management, work ability and satisfaction with working time, handover shifts and schedules were also better in attractive hospitals (P < 0.001). Job satisfaction and commitment were higher in attractive hospitals, whereas burnout and intention to leave were lower (P < 0.001). Organizational characteristics are key factors in nurse attraction and retention. Nurses face difficulties in their work situations, but some hospitals are perceived as healthy organizations. The concept of attractive institutions could serve as a catalyst for improvement in nurses\u2019 work environments in Europe

An integrative review of the factors influencing older nurses’ timing of retirement

Aims: To summarise the international empirical literature to provide a comprehensive understanding of older nurses’ decision making surrounding the timing of their retirement. Background: The global nursing shortage is increasing. Amongst some countries it has become an economic imperative to consider raising the state pension age and to extend working lives. Design: An integrative literature review using an integrated design. Data sources: MEDLINE, CINAHL and Business Source Premier databases were searched for studies between January 2007 ‐ October 2019. Review Methods: Quality appraisal of the studies were conducted. Findings were summarised, grouped into categories and themes extracted. Two models were developed for data representation. Results: 132 studies were identified by the search strategy. Of these, 27 articles were included for appraisal and synthesis. 16 papers were quantitative, seven qualitative and four mixed methods. The research took place in 13 different geographical locations. Most studies were of a questionnaire design, followed by interviews and focus groups. The total participant sample was 35,460. Through a synthesis of the studies, four themes were identified: Health, Well‐being and Family factors; Employer factors; Professional factors; Financial factors. Conclusion: This review revealed the heterogeneity of studies on this subject and confirmed previous findings but also established a ranking of criteria that influences nurses’ decision making: age, followed by personal and organisational factors. Four extracted themes of push and pull factors map onto these factors. No ‘one‐size‐fits‐all’ strategy exists to ensure the extension of older nurses’ working lives. Organisations need to foster an environment where older nurses feel respected and heard and where personal and professional needs are addressed

Structural, Vibrational, and Electronic Study of α‑As2Te3 under Compression

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry C, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acs.jpcc.6b06049We report a study of the structural, vibrational, and electronic properties of layered monoclinic arsenic telluride (α-As2Te3) at high pressures. Powder X-ray diffraction and Raman scattering measurements up to 17 GPa have been complemented with ab initio total-energy, lattice dynamics, and electronic band structure calculations. Our measurements, which include previously unreported Raman scattering measurements for crystalline α-As2Te3, show that this compound undergoes a reversible phase transition above 14 GPa at room temperature. The monoclinic crystalline structure of α-As2Te3 and its behavior under compression are analyzed by means of the compressibility tensor. Major structural and vibrational changes are observed in the range between 2 and 4 GPa and can be ascribed to the strengthening of interlayer bonds. No evidence of any isostructural phase transition has been observed in α-As2Te3. A comparison with other group 15 sesquichalcogenides allows understanding the structure of α-As2Te3 and its behavior under compression based on the activity of the cation lone electron pair in these compounds. Finally, our electronic band structure calculations show that α-As2Te3 is a semiconductor at 1 atm, which undergoes a trivial semiconducting−metal transition above 4 GPa. The absence of a pressure-induced electronic topological transition in α-As2Te3 is discussed.This work has been performed under financial support from Projects MAT2013-46649-C4-2-P, MAT2013-46649-C4-3-P, MAT2015-71070-REDC, FIS2013-48286-C2-1-P, and FIS2013-48286-C2-2-P of the Spanish Ministry of Economy and Competitiveness (MINECO), and the Department of Education, Universities and Research of the Basque Government and UPV/EHU (Grant No. IT756-13). This publication is also fruit of "Programa de Valoracion y Recursos Conjuntos de I+D+i VLC/CAMPUS" and has been financed by the Spanish Ministerio de Educacion, Cultura y Deporte as part of "Programa Campus de Excelencia Internacional" through Projects SP20140701 and SP20140871. Finally, authors thank ALBA Light Source for beam allocation at beamline MSPD.Cuenca Gotor, VP.; Sans-Tresserras, JÁ.; Ibáñez, J.; Popescu, C.; Gomis, O.; Vilaplana Cerda, RI.; Manjón Herrera, FJ.... (2016). Structural, Vibrational, and Electronic Study of α‑As2Te3 under Compression. Journal of Physical Chemistry C. 120(34):19340-19352. https://doi.org/10.1021/acs.jpcc.6b06049S19340193521203

Challenges in physician supply planning: the case of Belgium

<p>Abstract</p> <p>Introduction</p> <p>Planning human resources for health (HRH) is a complex process for policy-makers and, as a result, many countries worldwide swing from surplus to shortage. In-depth case studies can help appraising the challenges encountered and the solutions implemented. This paper has two objectives: to identify the key challenges in HRH planning in Belgium and to formulate recommendations for an effective HRH planning, on the basis of the Belgian case study and lessons drawn from an international benchmarking.</p> <p>Case description</p> <p>In Belgium, a numerus clausus set up in 1997 and effective in 2004, aims to limit the total number of physicians working in the curative sector. The assumption of a positive relationship between physician densities and health care utilization was a major argument in favor of medical supply restrictions. This new regulation did not improve recurrent challenges such as specialty imbalances, with uncovered needs particularly among general practitioners, and geographical maldistribution. New difficulties also emerged. In particular, limiting national training of HRH turned out to be ineffective within the open European workforce market. The lack of integration of policies affecting HRH was noteworthy. We described in the paper what strategies were developed to address those challenges in Belgium and in neighboring countries.</p> <p>Discussion and evaluation</p> <p>Planning the medical workforce involves determining the numbers, mix, and distribution of health providers that will be required at some identified future point in time. To succeed in their task, health policy planners have to take a broader perspective on the healthcare system. Focusing on numbers is too restrictive and adopting innovative policies learned from benchmarking without integration and coordination is unfruitful. Evolving towards a strategic planning is essential to control the effects of the complex factors impacting on human resources. This evolution requires an effective monitoring of all key factors affecting supply and demand, a dynamic approach, and a system-level perspective, considering all healthcare professionals, and integrating manpower planning with workforce development.</p> <p>Conclusion</p> <p>To engage in an evidence-based action, policy-makers need a global manpower picture, from their own country and abroad, as well as reliable and comparable manpower databases allowing proper analysis and planning of the workforce.</p