Observation of a Cs-induced state in the band gap of GaP(110): Alkali-metal bonding and Fermi-level pinning

The deposition of submonolayer quantities of Cs onto GaP(110) causes strong photoemission features in the region of the semiconductor fundamental band gap. This observation is interpreted in terms of emission from a hybrid state caused by the interaction of the Cs 6s level with the unoccupied dangling-bond state. This hybrid state has long been postulated in descriptions of the metal-semiconductor surface bond, and is responsible for the pinning of the Fermi level. The absence of dispersion in the state suggests that Cs/GaP(110) represents a realization of a Mott-Hubbard insulator, by comparison with results from other alkali-metal/compound-semiconductor systems

Transport, magnetic, and structural properties of La0.7_{0.7}Ce0.3_{0.3}MnO3_3 thin films. Evidence for hole-doping

Cerium-doped manganite thin films were grown epitaxially by pulsed laser deposition at $720 ^\circ$C and oxygen pressure $p_{O_2}=1-25$Pa and were subjected to different annealing steps. According to x-ray diffraction (XRD) data, the formation of CeO$_2$ as a secondary phase could be avoided for $p_{O_2}\ge 8$Pa. However, transmission electron microscopy shows the presence of CeO$_2$ nanoclusters, even in those films which appear to be single phase in XRD. With O$_2$ annealing, the metal-to-insulator transition temperature increases, while the saturation magnetization decreases and stays well below the theoretical value for electron-doped La$_{0.7}$Ce$_{0.3}$MnO$_3$ with mixed Mn$^{3+}$/Mn$^{2+}$ valences. The same trend is observed with decreasing film thickness from 100 to 20 nm, indicating a higher oxygen content for thinner films. Hall measurements on a film which shows a metal-to-insulator transition clearly reveal holes as dominating charge carriers. Combining data from x-ray photoemission spectroscopy, for determination of the oxygen content, and x-ray absorption spectroscopy (XAS), for determination of the hole concentration and cation valences, we find that with increasing oxygen content the hole concentration increases and Mn valences are shifted from 2+ to 4+. The dominating Mn valences in the films are Mn$^{3+}$ and Mn$^{4+}$, and only a small amount of Mn$^{2+}$ ions can be observed by XAS. Mn$^{2+}$ and Ce$^{4+}$ XAS signals obtained in surface-sensitive total electron yield mode are strongly reduced in the bulk-sensitive fluorescence mode, which indicates hole-doping in the bulk for those films which do show a metal-to-insulator transition.Comment: 8 pages, 10 figure

YBa2_2Cu3_3O7_7/La0.7_{0.7}Ca0.3_{0.3}MnO3_3 bilayers: Interface coupling and electric transport properties

Heteroepitaxially grown bilayers of ferromagnetic La$_{0.7}$Ca$_{0.3}$MnO$_3$ (LCMO) on top of superconducting YBa$_2$Cu$_3$O$_7$ (YBCO) thin films were investigated by focusing on electric transport properties as well as on magnetism and orbital occupation at the interface. Transport measurements on YBCO single layers and on YBCO/LCMO bilayers, with different YBCO thickness $d_Y$ and constant LCMO thickness $d_L=50$\,nm, show a significant reduction of the superconducting transition temperature $T_c$ only for $d_Y<10$\,nm,with only a slightly stronger $T_c$ suppression in the bilayers, as compared to the single layers. X-ray magnetic circular dichroism (XMCD) measurements confirm recently published data of an induced magnetic moment on the interfacial Cu by the ferromagnetically ordered Mn ions, with antiparallel alignment between Cu and Mn moments. However, we observe a significantely larger Cu moment than previously reported, indicating stronger coupling between Cu and Mn at the interface. This in turn could result in an interface with lower transparency, and hence smaller spin diffusion length, that would explain our electric transport data, i.e.smaller $T_c$ suppression. Moreover, linear dichroism measurements did not show any evidence for orbital reconstruction at the interface, indicating that a large change in orbital occupancies through hybridization is not necessary to induce a measurable ferromagnetic moment on the Cu atoms.Comment: 8 Figure

An analysis of photoemission and inverse photoemission spectra of Si(111) and sulphur-passivated InP(001) surfaces

Photoemission (PES) and inverse-photoemission spectra (IPES) for the sulphur-passivated InP(001) surface are compared with theoretical predictions based on density-functional calculations. As a test case for our methods, we also present a corresponding study of the better known Si(111) surface. The reported spectra for InP(001)-S agree well with the calculated ones if the surface is assumed to consist of a mixture of two phases, namely, the fully S-covered $(2\times2)$-reconstructed structure, which contains four S atoms in the surface unit-cell, and a $(2\times2)$ structure containing two S and two P atoms per unit cell. The latter has recently been identified in total-energy calculations as well as in core-level spectra of S-passivated Si(111)-$(2\times1)$ is in excellent agreement with the calculations. The comparison of the experimental-PES with our calculations provides additional considerations regarding the nature of the sample surface. It is also found that the commonly-used density-of-states approximation to the photo- and inverse- photoemission spectra is not valid for these systems.Comment: Submitted to Phys. Rev. B; 6 postscript formatted pages; 7 figures in gif format; postscript figures available upon reques

Enabling nursing students to focus on the Ottawa Charter and the nurses role in tackling inequalities in health through international exchange

Student nurses in a transatlantic exchange program explored the role of registered nurses in five countries’ public health systems. The Ottawa Charter provided a framework for students to examine the nurse’s responsibilities in public health. Students took practice placements in geographically rural areas on another continent and explored inequalities in health care. If nurses are to understand their role in the health care system then they must be taught the scope of their practice including their role in health promotion, public health practice and community development. For this project nursing instructors developed an assignment relevant to the aims and suitable for students in all five nursing programs. Only three of 48 students offered an assignment which focused on building healthy public policy. Nurse educators need to explore this further to ensure nurses of the future are aware of their role and responsibilities in this area and have skills to work effectively to influence and build healthy policy. The international student exchange supported the students’ developing understanding of the breadth of initiatives around the globe where nurses are actively engaged in addressing inequalities of health. Findings from an analysis of their assignments are presented in this evaluative report

Effect of Convalescent Plasma on Organ Support-Free Days in Critically Ill Patients With COVID-19: A Randomized Clinical Trial

Importance: The evidence for benefit of convalescent plasma for critically ill patients with COVID-19 is inconclusive. Objective: To determine whether convalescent plasma would improve outcomes for critically ill adults with COVID-19. Design, Setting, and Participants: The ongoing Randomized, Embedded, Multifactorial, Adaptive Platform Trial for Community-Acquired Pneumonia (REMAP-CAP) enrolled and randomized 4763 adults with suspected or confirmed COVID-19 between March 9, 2020, and January 18, 2021, within at least 1 domain; 2011 critically ill adults were randomized to open-label interventions in the immunoglobulin domain at 129 sites in 4 countries. Follow-up ended on April 19, 2021. Interventions: The immunoglobulin domain randomized participants to receive 2 units of high-titer, ABO-compatible convalescent plasma (total volume of 550 mL ± 150 mL) within 48 hours of randomization (n = 1084) or no convalescent plasma (n = 916). Main Outcomes and Measures: The primary ordinal end point was organ support-free days (days alive and free of intensive care unit-based organ support) up to day 21 (range, -1 to 21 days; patients who died were assigned -1 day). The primary analysis was an adjusted bayesian cumulative logistic model. Superiority was defined as the posterior probability of an odds ratio (OR) greater than 1 (threshold for trial conclusion of superiority &gt;99%). Futility was defined as the posterior probability of an OR less than 1.2 (threshold for trial conclusion of futility &gt;95%). An OR greater than 1 represented improved survival, more organ support-free days, or both. The prespecified secondary outcomes included in-hospital survival; 28-day survival; 90-day survival; respiratory support-free days; cardiovascular support-free days; progression to invasive mechanical ventilation, extracorporeal mechanical oxygenation, or death; intensive care unit length of stay; hospital length of stay; World Health Organization ordinal scale score at day 14; venous thromboembolic events at 90 days; and serious adverse events. Results: Among the 2011 participants who were randomized (median age, 61 [IQR, 52 to 70] years and 645/1998 [32.3%] women), 1990 (99%) completed the trial. The convalescent plasma intervention was stopped after the prespecified criterion for futility was met. The median number of organ support-free days was 0 (IQR, -1 to 16) in the convalescent plasma group and 3 (IQR, -1 to 16) in the no convalescent plasma group. The in-hospital mortality rate was 37.3% (401/1075) for the convalescent plasma group and 38.4% (347/904) for the no convalescent plasma group and the median number of days alive and free of organ support was 14 (IQR, 3 to 18) and 14 (IQR, 7 to 18), respectively. The median-adjusted OR was 0.97 (95% credible interval, 0.83 to 1.15) and the posterior probability of futility (O

Interactions between Natural Populations of Human and Rodent Schistosomes in the Lake Victoria Region of Kenya: A Molecular Epidemiological Approach

One of the world's most prevalent neglected diseases is schistosomiasis, which infects approximately 200 million people worldwide. Schistosoma mansoni is transmitted to humans by skin penetration by free-living larvae that develop in freshwater snails. The origin of this species is East Africa, where it coexists with its sister species, S. rodhaini. Interactions between these species potentially influence their epidemiology, ecology, and evolutionary biology, because they infect the same species of hosts and can hybridize. Over two years, we examined their distribution in Kenya to determine their degree of overlap geographically, within snail hosts, and in the water column as infective stages. Both species were spatially and temporally patchy, although S. mansoni was eight times more common than S. rodhaini. Both species overlap in the time of day they were present in the water column, which increases the potential for the species to coinfect the same host and interbreed. Peak infective time for S. mansoni was midday and dawn and dusk for S. rodhaini. Three snails were coinfected, which was more common than expected by chance. These findings indicate a lack of obvious isolating mechanisms to prevent hybridization, raising the intriguing question of how the two species retain separate identities

Low-value clinical practices in adult traumatic brain injury : an umbrella review

Despite numerous interventions and treatment options, the outcomes of traumatic brain injury (TBI) have improved little over the last 3 decades, which raises concern about the value of care in this patient population. We aimed to synthesize the evidence on 14 potentially low-value clinical practices in TBI care. Using umbrella review methodology, we identified systematic reviews evaluating the effectiveness of 14 potentially low-value practices in adults with acute TBI. We present data on methodological quality (Assessing the Methodological Quality of Systematic Reviews), reported effect sizes, and credibility of evidence (I to IV). The only clinical practice with evidence of benefit was therapeutic hypothermia (credibility of evidence II to IV). However, the most recent meta-analysis on hypothermia based on high-quality trials suggested harm (credibility of evidence IV). Meta-analyses on platelet transfusion for patients on antiplatelet therapy were all consistent with harm but were statistically non-significant. For the following practices, effect estimates were consistently close to the null: computed tomography (CT) in adults with mild TBI who are low-risk on a validated clinical decision rule; repeat CT in adults with mild TBI on anticoagulant therapy with no clinical deterioration; antibiotic prophylaxis for external ventricular drain placement; and decompressive craniectomy for refractory intracranial hypertension. We identified five clinical practices with evidence of lack of benefit or harm. However, evidence could not be considered to be strong for any clinical practice as effect measures were imprecise and heterogeneous, systematic reviews were often of low quality, and most included studies had a high risk of bias