Spin-dependent transport in metal/semiconductor tunnel junctions

This paper describes a model as well as experiments on spin-polarized tunnelling with the aid of optical spin orientation. This involves tunnel junctions between a magnetic material and gallium arsenide (GaAs), where the latter is optically excited with circularly polarized light in order to generate spin-polarized carriers. A transport model is presented that takes account of carrier capture in the semiconductor surface states, and describes the semiconductor surface in terms of a spin-dependent energy distribution function. The so-called surface spin-splitting can be calculated from the balance of the polarized electron and hole flow in the semiconductor subsurface region, the polarized tunnelling current across the tunnel barrier between the magnetic material and the semiconductor surface, and the spin relaxation at the semiconductor surface. Measurements are presented of the circular-polarization-dependent photocurrent (the so-called helicity asymmetry) in thin-film tunnel junctions of Co/Al2O3/GaAs. In the absence of a tunnel barrier, the helicity asymmetry is caused by magneto-optical effects (magnetic circular dichroism). In the case where a tunnel barrier is present, the data cannot be explained by magneto-optical effects alone; the deviations provide evidence that spin-polarized tunnelling due to optical spin orientation occurs. In Co/τ-MnAl/AlAs/GaAs junctions no deviations from the magneto-optical effects are observed, most probably due to the weak spin polarization of τ-MnAl along the tunnelling direction; the latter is corroborated by bandstructure calculations. Finally, the application of photoexcited GaAs for spin-polarized tunnelling in a scanning tunnelling microscope is discussed.

Follow-Up of Offspring Born to Parents With a Solid Organ Transplantation:A Systematic Review

Pregnancy after solid organ transplantation (SOT) has potential risks for the offspring. Most existing research focused on short-term pregnancy outcomes. The aim of this systematic review was to evaluate available data concerning longer term outcomes (>1 year) of these children. A systematic literature search, following PRISMA guidelines, of PubMed and Embase was performed from the earliest date of inception through to 6th April 2022. Publications on all types of (combined) SOT were eligible for inclusion. In total, 53 articles were included. The majority assessed offspring after kidney (78% of offspring) or liver transplantation (17% of offspring). 33 studies included offspring aged >4 years and five offspring aged >18 years. One study was included on fathers with SOT. The majority of the 1,664 included children after maternal SOT had normal intellectual, psychomotor, and behavioral development. Although prematurity and low birth weight were commonly present, regular growth after 1 year of age was described. No studies reported opportunistic or chronic infections or abnormal response to vaccinations. In general, pregnancy after SOT appears to have reassuring longer term outcomes for the offspring. However, existing information is predominantly limited to studies with young children. Longer prospective studies with follow-up into adulthood of these children are warranted

Validation of active forest fires detected by MSG-SEVIRI by means of MODIS hot spots and AWiFS images.

The detection of forest fires and the determination of their parameters have been usually carried out by polar-orbit sensors: AVHRR, (A)ATSR, BIRD and MODIS mainly. However, their time resolution prevents them from operating in real time. In contrast, the new geostationary sensors have very appropriate capacities for the observation of the Earth and monitoring of forest fires, as is being proved. GOES, MSG and MTSAT are already operative and they have led the international community to think that the global observation network in real time may become a reality. The implementation of this network is the aim of the Global Observations of Forest Cover and Land Cover Dynamics (GOFC/GOLD) FIRE Mapping and Monitoring program, focused internationally on taking decisions concerning the research of the Global Change. In this paper, the operation in real time by the MSG-SEVIRI sensor over the Iberian Peninsula is studied. On the other hand, the reliability of validation results by means of polar sensors, with better spatial resolution, is difficult to analyze due to errors caused by confused location of fires. This paper tries to find the most appropriate spatial scale to carry out comparison between Terra/Aqua-MODIS and Resourcesat1-AWiFS image

Role of Protein Biomarkers in the Detection of High-Grade Disease in Cervical Cancer Screening Programs

Since the Pap test was introduced in the 1940s, there has been an approximately 70% reduction in the incidence of squamous cell cervical cancers in many developed countries by the application of organized and opportunistic screening programs. The efficacy of the Pap test, however, is hampered by high interobserver variability and high false-negative and false-positive rates. The use of biomarkers has demonstrated the ability to overcome these issues, leading to improved positive predictive value of cervical screening results. In addition, the introduction of HPV primary screening programs will necessitate the use of a follow-up test with high specificity to triage the high number of HPV-positive tests. This paper will focus on protein biomarkers currently available for use in cervical cancer screening, which appear to improve the detection of women at greatest risk for developing cervical cancer, including Ki-67, p16INK4a, BD ProEx C, and Cytoactiv HPV L1

Formative peer assessment in a CSCL environment

In this case study our aim was to gain more insight in the possibilities of qualitative formative peer assessment in a computer supported collaborative learning (CSCL) environment. An approach was chosen in which peer assessment was operationalised in assessment assignments and assessment tools that were embedded in the course material. The course concerned a higher education case-based virtual seminar, in which students were asked to conduct research and write a report in small multidisciplinary teams. The assessment assignments contained the discussion of assessment criteria, the assessment of a group report of a fellow group, and writing an assessment report. A list of feedback rules was one of the assessment tools. A qualitative oriented study was conducted, focussing on the attitude of students towards peer assessment and practical use of peer assessment assignments and tools. Results showed that students’ attitude towards peer assessment was positive and that assessment assignments had added value. However, not all students fulfilled all assessment assignments. Recommendations for implementation of peer assessment in CSCL environments as well as suggestions for future research are discussed

Effectiveness and cost-effectiveness of a nurse-delivered intervention to improve adherence to treatment for HIV : a pragmatic, multicentre, open-label, randomised clinical trial

This trial was funded from public money by the Netherlands Organisation for Health Research and Development (ZonMW; grant number 171002208). Aardex provided support on the development of the study website. We thank all the HIV nurses and physicians from the seven HIV clinics involved in the AIMS study for their input and collaboration (Academic Medical Centre, Slotervaart hospital, and St. Lucas-Andreas hospital, all in Amsterdam; the Leiden University Medical Centre, Leiden; HAGA hospital, The Hague; Erasmus Medical Centre, Rotterdam; and Isala clinic, Zwolle), the study participants, and the Stichting HIV Monitoring (SHM) for their support in accessing the SHM database for identifying patient inclusion criteria and developing the Markov model. Finally, we thank and remember Herman Schaalma (deceased) for his contribution to the study design and grant application.Peer reviewedPostprin

Unified description of ballistic and diffusive carrier transport in semiconductor structures

A unified theoretical description of ballistic and diffusive carrier transport in parallel-plane semiconductor structures is developed within the semiclassical model. The approach is based on the introduction of a thermo-ballistic current consisting of carriers which move ballistically in the electric field provided by the band edge potential, and are thermalized at certain randomly distributed equilibration points by coupling to the background of impurity atoms and carriers in equilibrium. The sum of the thermo-ballistic and background currents is conserved, and is identified with the physical current. The current-voltage characteristic for nondegenerate systems and the zero-bias conductance for degenerate systems are expressed in terms of a reduced resistance. For arbitrary mean free path and arbitrary shape of the band edge potential profile, this quantity is determined from the solution of an integral equation, which also provides the quasi-Fermi level and the thermo-ballistic current. To illustrate the formalism, a number of simple examples are considered explicitly. The present work is compared with previous attempts towards a unified description of ballistic and diffusive transport.Comment: 23 pages, 10 figures, REVTEX

Handmade Wellbeing Handbook : Facilitating art and craft workshops for older people in care settings

This handbook was developed during international Handmade Wellbeing project, coordinated by the University of Helsinki, Sirpa Kokko. The project was Funded by European Union Erasmus+ Programme. The European Commission accepts no responsibility for the contents of the publication.Making crafts can enhance the wellbeing of older people. Research shows that engaging in arts and crafts improves the mood, gives the feeling of ability and provides opportunities for socialising. Making crafts also activates and sustains abilities that are necessary in activities of daily living, such as cognitive skills, memory and hand function. Therefore, creative arts and crafts activities should be included in wellbeing services for older people, both for those who live at home and for those who live in care homes. But what aspects should be considered in the planning and facilitation of craft activities for older people? The purpose of the Handmade Wellbeing Handbook is to provide the arts and crafts facilitator with information and ideas about developing pedagogical thinking and practical arrangements of the craft workshops. The handbook explores the special features of working with older people, for example, choosing suitable materials, techniques and working methods as well as communication, the importance of feedback and cooperation with care settings. In addition, the handbook presents practical examples of craft workshops that have been conducted in care settings. The publication is intended to be a resource for educational purposes especially in the fields of arts, culture, social and health care, as well as for professionals working with older people. The Handmade Wellbeing Handbook has been created during the Handmade Wellbeing project. The aim of this Erasmus+ project was to enhance and expand the professional competences of arts and crafts practitioners to facilitate craft activities in elderly care contexts. During the project (1.9.2015 – 31.8.2017), students and professionals from partner countries Finland, UK, Austria and Estonia conducted arts and crafts workshops in care settings in their respective countries. Experiences and practices of facilitating crafts for older people were shared in international training sessions, and now they have been compiled into a practical and inspirational Handmade Wellbeing Handbook

Non-nucleoside reverse transcriptase inhibitor-based combination antiretroviral therapy is associated with lower cell-associated hiv rna and dna levels as compared with therapy based on protease inhibitors

BACKGROUND: It remains unclear whether combination antiretroviral therapy (ART) regimens differ in their ability to fully suppress HIV replication. Here, we report the results of two crosssectional studies that compared levels of cell-associated (CA) HIV markers between individuals receiving suppressive ART containing either a non-nucleoside reverse transcriptase inhibitor (NNRTI) or a protease inhibitor (PI). METHODS: CA HIV unspliced RNA and total HIV DNA were quantified in two cohorts (n=100, n=124) of individuals treated with triple ART regimens consisting of two nucleoside reverse transcriptase inhibitors (NRTIs) plus either a NNRTI or a PI. To compare CA HIV RNA and DNA levels between the regimens, we built multivariable models adjusting for age, gender, current and nadir CD4+ count, plasma viral load zenith, duration of virological suppression, NRTI backbone composition, low-level plasma HIV RNA detectability, and electronically-measured adherence to ART. RESULTS: In both cohorts, levels of CA HIV RNA and DNA strongly correlated (rho=0.70 and rho=0.54) and both markers were lower in NNRTI-treated than in PI-treated individuals. In the multivariable analysis, CA RNA in both cohorts remained significantly reduced in NNRTI-treated individuals (padj=0.02 in both cohorts), with a similar but weaker association between the ART regimen and total HIV DNA (padj=0.048 and padj=0.10). No differences in CA HIV RNA or DNA levels were observed between individual NNRTIs or individual PIs, but CA HIV RNA was lower in individuals treated with either nevirapine or efavirenz, compared to PI-treated individuals CONCLUSIONS: All current classes of antiretroviral drugs only prevent infection of new cells but do not inhibit HIV RNA transcription in long-lived reservoir cells. Therefore, these differences in CA HIV RNA and DNA levels by treatment regimen suggest that NNRTIs are more potent in suppressing HIV residual replication than PIs, which may result in a smaller viral reservoir size