Terahertz quantum Hall effect for spin-split heavy-hole gases in strained Ge quantum wells

Spin-split heavy-hole gases in strained germanium quantum wells were characterized by polarisation-resolved terahertz time-domain spectroscopy. Effective masses, carrier densities, g-factors, transport lifetimes, mobilities and Rashba spin-splitting energies were evaluated, giving quantitative insights into the influence of strain. The Rashba coefficient was found to lower for samples with higher biaxial compressive strain, while heavy-hole mobilities were enhanced to over $1.5\times {10}^{6}$ cm2 V−1 s−1 at 3 K. This high mobility enabled the observation of the optical quantum Hall effect at terahertz frequencies for spin-split two-dimensional heavy-holes, evidenced as plateaux in the transverse magnetoconductivity at even and odd filling factors

Central extensions of groups of sections

If q : P -> M is a principal K-bundle over the compact manifold M, then any invariant symmetric V-valued bilinear form on the Lie algebra k of K defines a Lie algebra extension of the gauge algebra by a space of bundle-valued 1-forms modulo exact forms. In the present paper we analyze the integrability of this extension to a Lie group extension for non-connected, possibly infinite-dimensional Lie groups K. If K has finitely many connected components we give a complete characterization of the integrable extensions. Our results on gauge groups are obtained by specialization of more general results on extensions of Lie groups of smooth sections of Lie group bundles. In this more general context we provide sufficient conditions for integrability in terms of data related only to the group K.Comment: 54 pages, revised version, to appear in Ann. Glob. Anal. Geo

Portable Infrared Pupillometer in Patients With Subarachnoid Hemorrhage: Prognostic Value and Circadian Rhythm of the Neurological Pupil Index (NPi)

Background: Portable automated infrared pupillometry is becoming increasingly popular. To generate an objective reference base, the Neurological Pupil index (NPi) which combines different values of the pupillary light reflex is being introduced into clinical practice. In this explorative study, we examined different aspects of the NPi in relation to clinical severity and outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). Materials and Methods: Patients with serial assessment of the NPi (NeurOptics pupillometer NPi-200, Irvine, CA) starting no later than day 2 after aSAH onset were included in the study. Relative numbers of pathologic NPi’s, absolute NPi values, and their variances were compared according to aSAH clinical severity grade, functional outcome, and case fatality. The correlation between NPi and intracranial pressure, and NPi periodicity, were also examined. Results: In total, 18 patients with 4456 NPi values were eligible for inclusion in the analysis. The general trend of the NPi over time reflected the course of the neurological illness. Mean NPi tended to be lower in patients with clinically severe compared with nonsevere aSAH (3.75±0.40 vs. 4.56±0.06; P=0.171), and in patients with unfavorable compared with favorable outcomes (3.64±0.48 vs. 4.50±0.08; P=0.198). The mean variance of the NPi was higher in patients with severe compared with nonsevere aSAH (0.49±0.17 vs. 0.06±0.02; P=0.025). Pathologic NPi values were recorded more frequently in patients with severe compared with nonsevere aSAH (16.3%±8.8% vs. 0.0%±0.0%; P=0.002), and in those with unfavorable compared with favorable outcomes (19.2%±10.6% vs. 0.7%±0.6%; P=0.017). NPi was inversely correlated with intracranial pressure (Spearman r=−0.551, P<0.001). We observed a circadian pattern of NPi’s which was seemingly disrupted in patients with fatal outcome. Conclusions: On the basis of this preliminary study, the assessment of NPi by pupillometry is feasible and might complement multimodal neuromonitoring in patients with aSAH

Ultrastrong light-matter coupling at terahertz frequencies with split ring resonators and inter-Landau level transitions

We study strong light-matter coupling at terahertz frequencies employing a system based on an array of deeply subwavelength split ring resonators deposited on top of an ensemble of modulation-doped quantum wells. By applying a magnetic field parallel to the epitaxial growth axis, at low temperatures, Landau Levels are formed. We probe the interaction of the inter-Landau level transitions with the resonators modes, measuring a normalized coupling ratio Ωωc=0.58 between the inter-Landau level frequency ωc and the Rabi frequency Ω of the system. The physics of the system is studied as a function of the metasurface composition and of the number of quantum wells. We demonstrate that the light-matter coupling strength is basically independent from the metamaterial lattice spacing

A short purification process for quantitative isolation of PrP(Sc) from naturally occurring and experimental transmissible spongiform encephalopathies

BACKGROUND: Transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases affecting both humans and animals. They are associated with post-translational conversion of the normal cellular prion protein (PrP(C)) into a heat- and protease-resistant abnormal isoform (PrP(Sc)). Detection of PrP(Sc) in individuals is widely utilized for the diagnosis of prion diseases. METHODS: TSE brain tissue samples have been processed in order to quantitatively isolate PrP(Sc). The protocol includes an initial homogenization, digestion with proteinase K and salt precipitation. RESULTS: Here we show that over 97 percent of the PrP(Sc) present can be precipitated from infected brain material using this simple salting-out procedure for proteins. No chemically harsh conditions are used during the process in order to conserve the native quality of the isolated protein. CONCLUSION: The resulting PrP(Sc)-enriched preparation should provide a suitable substrate for analyzing the structure of the prion agent and for scavenging for other molecules with which it may associate. In comparison with most methods that exist today, the one described in this study is rapid, cost-effective and does not demand expensive laboratory equipment

Dengue-2 Structural Proteins Associate with Human Proteins to Produce a Coagulation and Innate Immune Response Biased Interactome

<p>Abstract</p> <p>Background</p> <p>Dengue virus infection is a public health threat to hundreds of millions of individuals in the tropical regions of the globe. Although Dengue infection usually manifests itself in its mildest, though often debilitating clinical form, dengue fever, life-threatening complications commonly arise in the form of hemorrhagic shock and encephalitis. The etiological basis for the virus-induced pathology in general, and the different clinical manifestations in particular, are not well understood. We reasoned that a detailed knowledge of the global biological processes affected by virus entry into a cell might help shed new light on this long-standing problem.</p> <p>Methods</p> <p>A bacterial two-hybrid screen using DENV2 structural proteins as bait was performed, and the results were used to feed a manually curated, global dengue-human protein interaction network. Gene ontology and pathway enrichment, along with network topology and microarray meta-analysis, were used to generate hypothesis regarding dengue disease biology.</p> <p>Results</p> <p>Combining bioinformatic tools with two-hybrid technology, we screened human cDNA libraries to catalogue proteins physically interacting with the DENV2 virus structural proteins, Env, cap and PrM. We identified 31 interacting human proteins representing distinct biological processes that are closely related to the major clinical diagnostic feature of dengue infection: haemostatic imbalance. In addition, we found dengue-binding human proteins involved with additional key aspects, previously described as fundamental for virus entry into cells and the innate immune response to infection. Construction of a DENV2-human global protein interaction network revealed interesting biological properties suggested by simple network topology analysis.</p> <p>Conclusions</p> <p>Our experimental strategy revealed that dengue structural proteins interact with human protein targets involved in the maintenance of blood coagulation and innate anti-viral response processes, and predicts that the interaction of dengue proteins with a proposed human protein interaction network produces a modified biological outcome that may be behind the hallmark pathologies of dengue infection.</p