Probing the Electronic Structure of Bilayer Graphene by Raman Scattering

The electronic structure of bilayer graphene is investigated from a resonant Raman study using different laser excitation energies. The values of the parameters of the Slonczewski-Weiss-McClure model for graphite are measured experimentally and some of them differ significantly from those reported previously for graphite, specially that associated with the difference of the effective mass of electrons and holes. The splitting of the two TO phonon branches in bilayer graphene is also obtained from the experimental data. Our results have implications for bilayer graphene electronic devices.Comment: 4 pages, 4 figure

Skyrmionic excitons

We investigate the properties of a Skyrmionic exciton consisting of a negatively charged Skyrmion bound to a mobile valence hole. A variational wave function is constructed which has the generalized total momentum P as a good quantum number. It is shown that the Skyrmionic exciton can have a larger binding energy than an ordinary magnetoexciton and should therefore dominate the photoluminescence spectrum in high-mobility quantum wells and heterojunctions where the electron-hole separation exceeds a critical value. The dispersion relation for the Skyrmionic exciton is discussed.Comment: 9 pages, RevTex, 2 PostScript figures. Replaced with version to appear in Phys. Rev. B Rapid Communications. Short discussion of variational state adde

Long-lived charged multiple-exciton complexes in strong magnetic fields

We consider the charged exciton complexes of an ideal two-dimensional electron-hole system in the limit of strong magnetic fields. A series of charged multiple-exciton states is identified and variational and finite-size exact diagonalization calculations are used to estimate their binding energies. We find that, because of a hidden symmetry, bound states of excitons and an additional electron cannot be created by direct optical absorption and, once created, have an infinite optical recombination lifetime. We also estimate the optical recombination rates when electron and hole layers are displaced and the hidden symmetry is violated.Comment: 12 pages + 2 PostScript figures, Revtex, Submitted to Phys. Rev. Let

Bradykinin or Acetylcholine as Vasodilators to Test Endothelial Venous Function in Healthy Subjects

INTRODUCTION: The evaluation of endothelial function has been performed in the arterial bed, but recently evaluation within the venous system has also been explored. Endothelial function studies employ different drugs that act as endothelium-dependent vasodilatory response inductors. OBJECTIVES: The aim of this study is to compare the endothelium-dependent venous vasodilator response mediated by either acetylcholine or bradykinin in healthy volunteers. METHODS AND RESULTS: Changes in vein diameter after phenylephrine-induced venoconstriction were measured to compare venodilation induced by acetylcholine or bradykinin (linear variable differential transformer dorsal hand vein technique). We studied 23 healthy volunteers; 31% were male, and the subject had a mean age of 33 ± 8 years and a mean body mass index of 23 ± 2 kg/m2. The maximum endothelium-dependent venodilation was similar for both drugs (p = 0.13), as well as the mean responses for each dose of both drugs (r = 0.96). The maximum responses to acetylcholine and bradykinin also had good agreement. CONCLUSION: There were no differences between acetylcholine and bradykinin as venodilators in this endothelial venous function investigation

Theory of Photoluminescence of the ν=1\nu=1 Quantum Hall State: Excitons, Spin-Waves and Spin-Textures

We study the theory of intrinsic photoluminescence of two-dimensional electron systems in the vicinity of the $\nu=1$ quantum Hall state. We focus predominantly on the recombination of a band of initial ``excitonic states'' that are the low-lying energy states of our model at $\nu=1$. It is shown that the recombination of excitonic states can account for recent observations of the polarization-resolved spectra of a high-mobility GaAs quantum well. The asymmetric broadening of the spectral line in the $\sigma_-$ polarization is explained to be the result of the ``shake-up'' of spin-waves upon radiative recombination of excitonic states. We derive line shapes for the recombination of excitonic states in the presence of long-range disorder that compare favourably with the experimental observations. We also discuss the stabilities and recombination spectra of other (``charged'') initial states of our model. An additional high-energy line observed in experiment is shown to be consistent with the recombination of a positively-charged state. The recombination spectrum of a negatively-charged initial state, predicted by our model but not observed in the present experiments, is shown to provide a direct measure of the formation energy of the smallest ``charged spin-texture'' of the $\nu=1$ state.Comment: 23 pages, 7 postscript figures included. Revtex with epsf.tex and multicol.sty. The revised version contains slightly improved numerical results and a few additional discussions of the result

Aging-related predictive factors for oxygenation improvement and mortality in COVID-19 and acute respiratory distress syndrome (ARDS) patients exposed to prone position: A multicenter cohort study

Background: Elderly patients are more susceptible to Coronavirus Disease-2019 (COVID-19) and are more likely to develop it in severe forms, (e.g., Acute Respiratory Distress Syndrome [ARDS]). Prone positioning is a treatment strategy for severe ARDS; however, its response in the elderly population remains poorly understood. The main objective was to evaluate the predictive response and mortality of elderly patients exposed to prone positioning due to ARDS-COVID-19. Methods: This retrospective multicenter cohort study involved 223 patients aged ≥ 65 years, who received prone position sessions for severe ARDS due to COVID-19, using invasive mechanical ventilation. The PaO2/FiO2 ratio was used to assess the oxygenation response. The 20-point improvement in PaO2/FiO2 after the first prone session was considered for good response. Data were collected from electronic medical records, including demographic data, laboratory/image exams, complications, comorbidities, SAPS III and SOFA scores, use of anticoagulants and vasopressors, ventilator settings, and respiratory system mechanics. Mortality was defined as deaths that occurred until hospital discharge. Results: Most patients were male, with arterial hypertension and diabetes mellitus as the most prevalent comorbidities. The non-responders group had higher SAPS III and SOFA scores, and a higher incidence of complications. There was no difference in mortality rate. A lower SAPS III score was a predictor of oxygenation response, and the male sex was a risk predictor of mortality. Conclusion: The present study suggests the oxygenation response to prone positioning in elderly patients with severe COVID-19-ARDS correlates with the SAPS III score. Furthermore, the male sex is a risk predictor of mortality

Muscle Phenotypic Variability in Limb Girdle Muscular Dystrophy 2 G

Abstract Limb girdle muscular dystrophy type 2 G (LGMD2G) is caused by mutations in the telethonin gene. Only few families were described presenting this disease, and they are mainly Brazilians. Here, we identified one additional case carrying the same common c.157C > T mutation in the telethonin gene but with an atypical histopathological muscle pattern. In a female patient with a long duration of symptoms (46 years), muscle biopsy showed, in addition to telethonin deficiency, the presence of nemaline rods, type 1 fiber predominance, nuclear internalization, lobulated fibers, and mitochondrial paracrystalline inclusions. Her first clinical signs were identified at 8 years old, which include tiptoe walking, left lower limb deformity, and frequent falls. Ambulation loss occurred at 41 years old, and now, at 54 years old, she presented pelvic girdle atrophy, winging scapula, foot deformity with incapacity to perform ankle dorsiflexion, and absent tendon reflexes. The presence of nemaline bodies could be a secondary phenomenon, possibly associated with focal Z-line abnormalities of a long-standing disease. However, these new histopathological findings, characteristic of congenital myopathies, expand muscle phenotypic variability of telethoninopathy

A Mouse to Human Search for Plasma Proteome Changes Associated with Pancreatic Tumor Development

Background: The complexity and heterogeneity of the human plasma proteome have presented significant challenges in the identification of protein changes associated with tumor development. Refined genetically engineered mouse (GEM) models of human cancer have been shown to faithfully recapitulate the molecular, biological, and clinical features of human disease. Here, we sought to exploit the merits of a well-characterized GEM model of pancreatic cancer to determine whether proteomics technologies allow identification of protein changes associated with tumor development and whether such changes are relevant to human pancreatic cancer. Methods and Findings: Plasma was sampled from mice at early and advanced stages of tumor development and from matched controls. Using a proteomic approach based on extensive protein fractionation, we confidently identified 1,442 proteins that were distributed across seven orders of magnitude of abundance in plasma. Analysis of proteins chosen on the basis of increased levels in plasma from tumor-bearing mice and corroborating protein or RNA expression in tissue documented concordance in the blood from 30 newly diagnosed patients with pancreatic cancer relative to 30 control specimens. A panel of five proteins selected on the basis of their increased level at an early stage of tumor development in the mouse was tested in a blinded study in 26 humans from the CARET (Carotene and Retinol Efficacy Trial) cohort. The panel discriminated pancreatic cancer cases from matched controls in blood specimens obtained between 7 and 13 mo prior to the development of symptoms and clinical diagnosis of pancreatic cancer. Conclusions: Our findings indicate that GEM models of cancer, in combination with in-depth proteomic analysis, provide a useful strategy to identify candidate markers applicable to human cancer with potential utility for early detection

Octreotide treatment of patients with hepatocellular carcinoma - a retrospective single centre controlled study

<p>Abstract</p> <p>Background</p> <p>Studies of treatment with octreotide of patients with hepatocellular carcinoma (HCC) gave conflicting results. We analyzed retrospectively the survival of our patients treated with octreotide monotherapy and compared it to stage-matched patients who received either TACE, multimodal therapy or palliative care.</p> <p>Methods</p> <p>95 patients seen at the department of Gastroenterology and Hepatology, Medical University of Vienna with HCC in BCLC stage A or B, who received either TACE, multimodal therapy, long-acting octreotide or palliative care were reviewed for this retrospective study.</p> <p>Results</p> <p>Survival rates of patients with BCLC stage B and any "active" treatment (long-acting octreotide, TACE or multimodal therapy) were significantly higher (22.4, 22.0, 35.5 months) compared to patients who received palliative care only (2.9 months). Survival rates of patients with BCLC stage A and "active" treatment (31.4, 37.3, 40.2 months) compared to patients who received only palliative care (15.1 months) did not show statistically significant differences. Octreotide monotherapy showed a similar outcome compared to patients who received TACE or multimodal therapy.</p> <p>Conclusion</p> <p>Survival under octreotide treatment was not different compared to TACE or multimodal therapy and might be a therapeutic option for patients with HCC.</p