Effect of annealing on the depth profile of hole concentration in (Ga,Mn)As

The effect of annealing at 250 C on the carrier depth profile, Mn distribution, electrical conductivity, and Curie temperature of (Ga,Mn)As layers with thicknesses > 200 nm, grown by molecular-beam epitaxy at low temperatures, is studied by a variety of analytical methods. The vertical gradient in hole concentration, revealed by electrochemical capacitance-voltage profiling, is shown to play a key role in the understanding of conductivity and magnetization data. The gradient, basically already present in as-grown samples, is strongly influenced by post-growth annealing. From secondary ion mass spectroscopy it can be concluded that, at least in thick layers, the change in carrier depth profile and thus in conductivity is not primarily due to out-diffusion of Mn interstitials during annealing. Two alternative possible models are discussed.Comment: 8 pages, 8 figures, to appear in Phys. Rev.

Curie temperature and carrier concentration gradients in MBE grown GaMnAs layers

We report on detailed investigations of the electronic and magnetic properties of ferromagnetic GaMnAs layers, which have been fabricated by low-temperature molecular-beam epitaxy. Superconducting quantum interference device measurements reveal a decrease of the Curie temperature from the surface to the GaMnAs/GaAs interface. While high resolution x-ray diffraction clearly shows a homogeneous Mn distribution, a pronounced decrease of the carrier concentration from the surface towards the GaMnAs/GaAs interface has been found by Raman spectroscopy as well as electrochemical capacitance-voltage profiling. The gradient in Curie temperature seems to be a general feature of GaMnAs layers grown at low-temperature. Possible explanations are discussed.Comment: 3 pages, 4 figures, submitted to AP

Subclinical thyroid function and cardiovascular events in patients with atrial fibrillation

Objective: To evaluate if subclinical thyroid dysfunction is associated with cardiovascular (CV) risk in patients with atrial fibrillation (AF). Methods: Swiss-AF is a prospective cohort of community-dwelling participants aged ≥ 65 years with AF. Primary outcome was a composite endpoint of CV events (myocardial infarctions, stroke/transitory ischemic events, systemic embolism, heart failure (HF) hospitalizations, CV deaths). Secondary outcomes were component endpoints, total mortality, and AF-progression. Exposures were thyroid dysfunction categories, TSH and fT4. Sensitivity analyses were performed for amiodarone use, thyroid hormones use, and competing events. Results: 2415 patients were included (mean age: 73.2 years; 27% women). 196 (8.4%) had subclinical hypothyroidism and 53 (2.3%) subclinical hyperthyroidism. Subclinical thyroid dysfunction was not associated with CV events, during a median follow-up of 2.1 years (max 5 years): age- and sex-adjusted hazard ratio (adjHR) of 0.99 (95% CI: 0.69-1.41) for subclinical hypothyroidism and 0.55 (95% CI: 0.23-1.32) for subclinical hyperthyroidism. Results remained robust following multivariable adjustment and sensitivity analyses. In euthyroid patients, fT4 levels were associated with an increased risk for the composite endpoint and HF (adjHR: 1.46, 95% CI: 1.04-2.05; adjHR: 1.70, 95% CI: 1.08-2.66, respectively, for the highest quintile vs the middle quintile). Results remained similar following multivariable adjustment and remained significant for HF in sensitivity analyses. No association between subclinical thyroid dysfunction and total mortality or AF-progression was found. Conclusions: Subclinical hypothyroidism was not associated with increased CV risk in AF patients. Higher levels of fT4 with normal TSH were associated with a higher risk for HF

Clientelism as civil society? Unpacking the relationship between clientelism and democracy at the local level in South Africa

This article, building on analyses from the global south, attempts to reframe democratic expectations by considering where previously maligned practices such as clientelism may hold moments of democracy. It does so by comparing the theory of civil society with that of clientelism, and its African counterpart neo-patrimonialism. It argues that clientelism as civil society may fulfil democratic tasks such as holding the (local) state accountable, strengthening civil and political liberties and providing channels of access for previously marginalised groups. Clientelism is not necessarily a reflection of imposed power relations but, at times, can demonstrate a conscious political strategy, to generate development, on the part of its protagonists.IS

Penumbral Rescue by normobaric O = O administration in patients with ischemic stroke and target mismatch proFile (PROOF): Study protocol of a phase IIb trial.

Oxygen is essential for cellular energy metabolism. Neurons are particularly vulnerable to hypoxia. Increasing oxygen supply shortly after stroke onset could preserve the ischemic penumbra until revascularization occurs. PROOF investigates the use of normobaric oxygen (NBO) therapy within 6 h of symptom onset/notice for brain-protective bridging until endovascular revascularization of acute intracranial anterior-circulation occlusion. Randomized (1:1), standard treatment-controlled, open-label, blinded endpoint, multicenter adaptive phase IIb trial. Primary outcome is ischemic core growth (mL) from baseline to 24 h (intention-to-treat analysis). Secondary efficacy outcomes include change in NIHSS from baseline to 24 h, mRS at 90 days, cognitive and emotional function, and quality of life. Safety outcomes include mortality, intracranial hemorrhage, and respiratory failure. Exploratory analyses of imaging and blood biomarkers will be conducted. Using an adaptive design with interim analysis at 80 patients per arm, up to 456 participants (228 per arm) would be needed for 80% power (one-sided alpha 0.05) to detect a mean reduction of ischemic core growth by 6.68 mL, assuming 21.4 mL standard deviation. By enrolling endovascular thrombectomy candidates in an early time window, the trial replicates insights from preclinical studies in which NBO showed beneficial effects, namely early initiation of near 100% inspired oxygen during short temporary ischemia. Primary outcome assessment at 24 h on follow-up imaging reduces variability due to withdrawal of care and early clinical confounders such as delayed extubation and aspiration pneumonia. ClinicalTrials.gov: NCT03500939; EudraCT: 2017-001355-31