3,708 research outputs found
Share of nations in 37 international public health journals : an equity and diversity perspective towards health research capacity building.
Background: This paper contributes to further exploration of inequity in access to health research capacity development by examining the representation of different nations in international public health journals. It also aims to examine the degree of diversity that exists in these journals.Methods: This study is a descriptive survey. It was done with objective sampling on 37 ISI health journals on October of 2008.The number and nationality of people in different editorial positions of the journals was identified. The second analysis involved recalculating the numbers obtained for each nation to the population size of nations per million inhabitants. In order to better compare countries in terms of presence in editorial team of the journals, a ‘public health editor equity gap ratio' (PHEEGR) was developed.Results: Low income countries have occupied none of the leadership positions of chief editor or associate /assistant chief editors and middle income countries at maximum shared less than 5 percent. The PHEEGR gap in access to the different editorial positions between highest to the lowest representation of countries was 16/1 for chief editors, 12/1 for associate editors , 335/1 for editorial boards and 202/1 for associate editorial boards. However, after normalizing the data to the country's population, the gap increased significantly.Conclusion: There is an imbalance and possibly even inequity in the composition of editorial boards and offices of international health journals that should be paid significant attention. This can contribute to fill the equity gap exists between health in developing and developed countries
Post-Stroke Working Memory Dysfunction: A Meta-Analysis and Systematic Review:A Meta-Analysis and Systematic Review
Risk factors for ischemic stroke and transient ischemic attack in patients under age 50
To analyze risk factors for ischemic stroke and transient ischemic attack (TIA) in young adults under the age of 50. To make recommendations for additional research and practical consequences. From 97 patients with ischemic stroke or TIA under the age of 50, classical cardiovascular risk factors, coagulation disorders, history of migraine, use of oral contraceptives, cardiac abnormalities on ECG and echocardiography, and the results of duplex ultrasound were retrospectively analyzed. Literature was reviewed and compared to the results. 56.4% of the patients had hypertension, 12.1% increased total cholesterol, 20% hypertriglyceridemia, 31.5% an increased LDL-level, 32.6% a decreased HDL-level and 7.2% a disturbed glucose tolerance. Thrombophilia investigation was abnormal in 21 patients and auto-immune serology was abnormal in 15 patients. Ten of these patients were already known with a systemic disease associated with an increased risk for ischemic stroke (i.e. systemic lupus erythematosus). The ECG was abnormal in 16.7% of the cases, the echocardiography in 12.1% and duplex ultrasound of the carotid arteries was in 31.8% of the cases abnormal. Conventional cardiovascular risk factors are not only important in patients over the age of 50 with ischemic stroke or TIA, but also in this younger population under the age of 50. Thrombophilia investigation and/ or autoimmune serology should be restricted to patients without conventional cardiovascular risk factors and a history or other clinical symptoms associated with hypercoagulability and/ or autoimmune diseases
Theory of Current-Driven Domain Wall Motion: A Poorman's Approach
A self-contained theory of the domain wall dynamics in ferromagnets under
finite electric current is presented.
The current is shown to have two effects; one is momentum transfer, which is
proportional to the charge current and wall resistivity (\rhow), and the
other is spin transfer, proportional to spin current.
For thick walls, as in metallic wires, the latter dominates and the threshold
current for wall motion is determined by the hard-axis magnetic anisotropy,
except for the case of very strong pinning.
For thin walls, as in nanocontacts and magnetic semiconductors, the
momentum-transfer effect dominates, and the threshold current is proportional
to \Vz/\rhow, \Vz being the pinning potential
Douchen in privé-huishoudens.
Onderzocht is hoe groot het watergebruik bij het douchen thuis is en of twee meetmethoden verschillende resultaten opleveren. Ook is gekeken naar het verschil in gebruik van conventionele en spaardouchekoppe
Gate-bias assisted charge injection in organic field-effect transistors
The charge injection barriers in organic field-effect transistors (OFETs) seem to be far less critical as compared to organic light-emitting diodes (OLEDs). Counter intuitively; we show that the origin is image-force lowering of the barrier due to the gate bias at the source contact; although the corresponding gate field is perpendicular to the channel current. In coplanar OFETs; injection barriers up to 1 eV can be surmounted by increasing the gate bias; enabling extraction of bulk transport parameters in this regime. For staggered transistors; however; the injection is gate-assisted only until the gate bias is screened by the accumulation channel opposite to the source contact. The gate-assisted injection is supported by two-dimensional numerical charge transport simulations that reproduce the gate-bias dependence of the contact resistance and the typical S-shaped output curves as observed for OFETs with high injection barriers.
Transfer Learning for Domain Adaptation in MRI: Application in Brain Lesion Segmentation
Magnetic Resonance Imaging (MRI) is widely used in routine clinical diagnosis
and treatment. However, variations in MRI acquisition protocols result in
different appearances of normal and diseased tissue in the images.
Convolutional neural networks (CNNs), which have shown to be successful in many
medical image analysis tasks, are typically sensitive to the variations in
imaging protocols. Therefore, in many cases, networks trained on data acquired
with one MRI protocol, do not perform satisfactorily on data acquired with
different protocols. This limits the use of models trained with large annotated
legacy datasets on a new dataset with a different domain which is often a
recurring situation in clinical settings. In this study, we aim to answer the
following central questions regarding domain adaptation in medical image
analysis: Given a fitted legacy model, 1) How much data from the new domain is
required for a decent adaptation of the original network?; and, 2) What portion
of the pre-trained model parameters should be retrained given a certain number
of the new domain training samples? To address these questions, we conducted
extensive experiments in white matter hyperintensity segmentation task. We
trained a CNN on legacy MR images of brain and evaluated the performance of the
domain-adapted network on the same task with images from a different domain. We
then compared the performance of the model to the surrogate scenarios where
either the same trained network is used or a new network is trained from
scratch on the new dataset.The domain-adapted network tuned only by two
training examples achieved a Dice score of 0.63 substantially outperforming a
similar network trained on the same set of examples from scratch.Comment: 8 pages, 3 figure
Relation between physical activity and cerebral small vessel disease: A nine-year prospective cohort study.
BACKGROUND AND AIMS: Given the unexplored potential of physical activity to reduce the progression of cerebral small vessel disease (cSVD, the purpose of this study was to prospectively (across nine-year follow-up) examine the relation between (baseline) physical activity and the (clinical and imaging) consequences of the whole spectrum of cerebral small vessel disease. METHODS: Five hundred and three patients with cerebral small vessel disease from the RUNDMC study were followed for nine years. Physical activity was assessed using a questionnaire in 2006, 2011, and 2015. Clinical events (i.e. all-cause mortality, cerebrovascular events (by stroke subtype)) were collected with a structured questionnaire. Patients underwent magnetic resonance imaging scanning for the assessment of magnetic resonance imaging markers of cerebral small vessel disease (i.e. white matter hyperintensities, lacunes, and microbleeds) and microstructural integrity of the white matter at three timepoints. RESULTS: The mean age at baseline was 66 (SD 9.0) years; 44% were women. A higher baseline physical activity level was independently associated with a lower all-cause mortality (HR: 0.69, 95%CI: 0.49-0.98, p = 0.03) and incidence of cerebrovascular disease (HR: 0.58, 95%CI: 0.36-0.96, p = 0.03). However, we found no relation between physical activity and incident lacunar stroke or progression of magnetic resonance imaging markers of cerebral small vessel disease. CONCLUSIONS: Whilst regular physical activity was not related to the progression of magnetic resonance imaging markers of cerebral small vessel disease across a nine-year follow-up, results from our study prove that high levels of physical activity in patients with cerebral small vessel disease are associated with a lower all-cause mortality and lower incidence of cerebrovascular events
Ab initio study of vacancy formation in cubic LaMnO3 and SmCoO3 as cathode materials in solid oxide fuel cells
© 2016 Author(s). Doped LaMnO3 and SmCoO3 are important solid oxide fuel cell cathode materials. The main difference between these two perovskites is that SmCoO3 has proven to be a more efficient cathode material than LaMnO3 at lower temperatures. In order to explain the difference in efficiency, we need to gain insight into the materials' properties at the atomic level. However, while LaMnO3 has been widely studied, ab initio studies on SmCoO3 are rare. Hence, in this paper, we perform a comparative DFT + U study of the structural, electronic, and magnetic properties of these two perovskites. To that end, we first determined a suitable Hubbard parameter for the Co d-electrons to obtain a proper description of SmCoO3 that fully agrees with the available experimental data. We next evaluated the impact of oxygen and cation vacancies on the geometry, electronic, and magnetic properties. Oxygen vacancies strongly alter the electronic and magnetic structures of SmCoO3, but barely affect LaMnO3. However, due to their high formation energy, their concentrations in the material are very low and need to be induced by doping. Studying the cation vacancy concentration showed that the formation of cation vacancies is less energetically favorable than oxygen vacancies and would thus not markedly influence the performance of the cathode
The Impact of Mixing Modes on Reliability in Longitudinal Studies
Mixed-mode designs are increasingly important in surveys, and large longitudinal studies are progressively moving to or considering such a design. In this context, our knowledge regarding the impact of mixing modes on data quality indicators in longitudinal studies is sparse. This study tries to ameliorate this situation by taking advantage of a quasi-experimental design in a longitudinal survey. Using models that estimate reliability for repeated measures, quasi-simplex models, 33 variables are analyzed by comparing a single-mode CAPI design to a sequential CATI-CAPI design. Results show no differences in reliabilities and stabilities across mixed modes either in the wave when the switch was made or in the subsequent waves. Implications and limitations are discussed. </jats:p
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