Quantum interference and Klein tunneling in graphene heterojunctions

The observation of quantum conductance oscillations in mesoscopic systems has traditionally required the confinement of the carriers to a phase space of reduced dimensionality. While electron optics such as lensing and focusing have been demonstrated experimentally, building a collimated electron interferometer in two unconfined dimensions has remained a challenge due to the difficulty of creating electrostatic barriers that are sharp on the order of the electron wavelength. Here, we report the observation of conductance oscillations in extremely narrow graphene heterostructures where a resonant cavity is formed between two electrostatically created bipolar junctions. Analysis of the oscillations confirms that p-n junctions have a collimating effect on ballistically transmitted carriers. The phase shift observed in the conductance fringes at low magnetic fields is a signature of the perfect transmission of carriers normally incident on the junctions and thus constitutes a direct experimental observation of ``Klein Tunneling.''Comment: 13 pages and 6 figures including supplementary information. The paper has been modified in light of new theoretical results available at arXiv:0808.048

Scintigraphic assessment of bone status at one year following hip resurfacing : comparison of two surgical approaches using SPECT-CT scan

Objectives: To study the vascularity and bone metabolism of the femoral head/neck following hip resurfacing arthroplasty, and to use these results to compare the posterior and the trochanteric-flip approaches. Methods: In our previous work, we reported changes to intra-operative blood flow during hip resurfacing arthroplasty comparing two surgical approaches. In this study, we report the vascularity and the metabolic bone function in the proximal femur in these same patients at one year after the surgery. Vascularity and bone function was assessed using scintigraphic techniques. Of the 13 patients who agreed to take part, eight had their arthroplasty through a posterior approach and five through a trochanteric-flip approach. Results: One year after surgery, we found no difference in the vascularity (vascular phase) and metabolic bone function (delayed phase) at the junction of the femoral head/neck between the two groups of patients. Higher radiopharmaceutical uptake was found in the region of the greater trochanter in the trochanteric-flip group, related to the healing osteotomy. Conclusions: Our findings using scintigraphic techniques suggest that the greater intra-operative reduction in blood flow to the junction of the femoral head/neck, which is seen with the posterior approach compared with trochanteric flip, does not result in any difference in vascularity or metabolic bone function one year after surgery

Troppo - A Python framework for the reconstruction of context-specific metabolic models

The surge in high-throughput technology availability for molecular biology has enabled the development of powerful predictive tools for use in many applications, including (but not limited to) the diagnosis and treatment of human diseases such as cancer. Genome-scale metabolic models have shown some promise in clearing a path towards precise and personalized medicine, although some challenges still persist. The integration of omics data and subsequent creation of context-specific models for specific cells/tissues still poses a significant hurdle, and most current tools for this purpose have been implemented using proprietary software. Here, we present a new software tool developed in Python, troppo - Tissue-specific RecOnstruction and Phenotype Prediction using Omics data, implementing a large variety of context-specific reconstruction algorithms. Our framework and workflow are modular, which facilitates the development of newer algorithms or omics data sources.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2019 unit and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. The authors also thank the PhD scholarships funded by national funds through Fundacao para a Ciencia e Tecnologia, with references: SFRH/BD/133248/2017 (J.F.), SFRH/BD/118657/2016 (V.V.).info:eu-repo/semantics/publishedVersio

Catheter-associated bacteremia by Mycobacterium senegalense in Korea

BACKGROUND: Rapidly growing mycobacteria is recognized as one of the causative agents of catheter-related infections, especially in immunocompromised hosts. To date, however, Mycobacterium senegalense, which was known as the principal pathogen of bovine farcy, has not been reported in human infection. CASE PRESENTATION: We describe the first case of human infection by M. senegalense, which has caused catheter-related bloodstream infection in a cancer patient in Korea. The microorganism was identified by the 16S rRNA gene, rpoB, and 16S-23S rRNA gene internal transcribed spacer (ITS) sequence analyses. CONCLUSION: Our first report of catheter-associated bacteremia caused by M. senegalense suggests the zoonotic nature of this species and indicates the expansion of mycobacterial species relating to human infection. M. senegalense should be considered as one of the causes of human infections in the clinical practice

Clusters of galaxies : observational properties of the diffuse radio emission

Clusters of galaxies, as the largest virialized systems in the Universe, are ideal laboratories to study the formation and evolution of cosmic structures...(abridged)... Most of the detailed knowledge of galaxy clusters has been obtained in recent years from the study of ICM through X-ray Astronomy. At the same time, radio observations have proved that the ICM is mixed with non-thermal components, i.e. highly relativistic particles and large-scale magnetic fields, detected through their synchrotron emission. The knowledge of the properties of these non-thermal ICM components has increased significantly, owing to sensitive radio images and to the development of theoretical models. Diffuse synchrotron radio emission in the central and peripheral cluster regions has been found in many clusters. Moreover large-scale magnetic fields appear to be present in all galaxy clusters, as derived from Rotation Measure (RM) studies. Non-thermal components are linked to the cluster X-ray properties, and to the cluster evolutionary stage, and are crucial for a comprehensive physical description of the intracluster medium. They play an important role in the cluster formation and evolution. We review here the observational properties of diffuse non-thermal sources detected in galaxy clusters: halos, relics and mini-halos. We discuss their classification and properties. We report published results up to date and obtain and discuss statistical properties. We present the properties of large-scale magnetic fields in clusters and in even larger structures: filaments connecting galaxy clusters. We summarize the current models of the origin of these cluster components, and outline the improvements that are expected in this area from future developments thanks to the new generation of radio telescopes.Comment: Accepted for the publication in The Astronomy and Astrophysics Review. 58 pages, 26 figure

Comparison of inpatient vs. outpatient anterior cervical discectomy and fusion: a retrospective case series

<p>Abstract</p> <p>Background</p> <p>Spinal surgery is increasingly being done in the outpatient setting. We reviewed our experience with inpatient and outpatient single-level anterior cervical discectomy and fusion with plating (ACDF+P).</p> <p>Methods</p> <p>All patients undergoing single-level anterior cervical discectomy and fusion with plating between August 2005 and May 2007 by two surgeons (RPB or JAF) were retrospectively reviewed. All patients underwent anterior cervical microdiscectomy, arthrodesis using structural allograft, and titanium plating. A planned change from doing ACDF+P on an inpatient basis to doing ACDF+P on an outpatient basis was instituted at the midpoint of the study. There were no other changes in technique, patient selection, instrumentation, facility, or other factors. All procedures were done in full-service hospitals accommodating outpatient and inpatient care.</p> <p>Results</p> <p>64 patients underwent ACDF+P as inpatients, while 45 underwent ACDF+P as outpatients. When outpatient surgery was planned, 17 patients were treated as inpatients due to medical comorbidities (14), older age (1), and patient preference (2). At a mean follow-up of 62.4 days, 90 patients had an excellent outcome, 19 patients had a good outcome, and no patients had a fair or poor outcome. There was no significant difference in outcome between inpatients and outpatients. There were 4 complications, all occurring in inpatients: a hematoma one week post-operatively requiring drainage, a cerebrospinal fluid leak treated with lumbar drainage, syncope of unknown etiology, and moderate dysphagia.</p> <p>Conclusion</p> <p>In this series, outpatient ACDF+P was safe and was not associated with a significant difference in outcome compared with inpatient ACDF+P.</p

Response of the primary auditory and non-auditory cortices to acoustic stimulation: A manganese-enhanced MRI study

Structural and functional features of various cerebral cortices have been extensively explored in neuroscience research. We used manganese-enhanced MRI, a non-invasive method for examining stimulus-dependent activity in the whole brain, to investigate the activity in the layers of primary cortices and sensory, such as auditory and olfactory, pathways under acoustic stimulation. Male Sprague-Dawley rats, either with or without exposure to auditory stimulation, were scanned before and 24-29 hour after systemic MnCl2 injection. Cortex linearization and layer-dependent signal extraction were subsequently performed for detecting layer-specific cortical activity. We found stimulus-dependent activity in the deep layers of the primary auditory cortex and the auditory pathways. The primary sensory and visual cortices also showed the enhanced activity, whereas the olfactory pathways did not. Further, we performed correlation analysis of the signal intensity ratios among different layers of each cortex, and compared the strength of correlations between with and without the auditory stimulation. In the primary auditory cortex, the correlation strength between left and right hemisphere showed a slight but not significant increase with the acoustic simulation, whereas, in the primary sensory and visual cortex, the correlation coefficients were significantly smaller. These results suggest the possibility that even though the primary auditory, sensory, and visual cortices showed enhanced activity to the auditory stimulation, these cortices had different associations for auditory processing in the brain network.open0

Wnt expression is not correlated with β-catenin dysregulation in Dupuytren's Disease

BACKGROUND: Dupuytren's contracture or disease (DD) is a fibro-proliferative disease of the hand that results in finger flexion contractures. Increased cellular β-catenin levels have been identified as characteristic of this disease. As Wnts are the most widely recognized upstream regulators of cellular β-catenin accumulation, we have examined Wnt gene expression in surgical specimens and in DD-derived primary cell cultures grown in two-dimensional monolayer culture or in three-dimensional FPCL collagen lattice cultures. RESULTS: The Wnt expression profile of patient-matched DD and unaffected control palmar fascia tissue was determined by a variety of complimentary methods; Affymetrix Microarray analysis, specific Wnt and degenerative primer-based Reverse Transcriptase (RT)-PCR, and Real Time PCR. Microarray analysis identified 13 Wnts associated with DD and control tissues. Degenerate Wnt RT-PCR analysis identified Wnts 10b and 11, and to a lesser extent 5a and 9a, as the major Wnt family members expressed in our patient samples. Competitive RT-PCR analysis identified significant differences between the levels of expression of Wnts 9a, 10b and 11 in tissue samples and in primary cell cultures grown as monolayer or in FPCL, where the mRNA levels in tissue > FPCL cultures > monolayer cultures. Real Time PCR data confirmed the down-regulation of Wnt 11 mRNA in DD while Wnt 10b, the most frequently isolated Wnt in DD and control palmar fascia, displayed widely variable expression between the methods of analysis. CONCLUSION: These data indicate that changes in Wnt expression per se are unlikely to be the cause of the observed dysregulation of β-catenin expression in DD

Dual Mechanism for the Translation of Subgenomic mRNA from Sindbis Virus in Infected and Uninfected Cells

Infection of BHK cells by Sindbis virus (SV) gives rise to a profound inhibition of cellular protein synthesis, whereas translation of viral subgenomic mRNA that encodes viral structural proteins, continues for hours. To gain further knowledge on the mechanism by which this subgenomic mRNA is translated, the requirements for some initiation factors (eIFs) and for the presence of the initiator AUG were examined both in infected and in uninfected cells. To this end, BHK cells were transfected with different SV replicons or with in vitro made SV subgenomic mRNAs after inactivation of some eIFs. Specifically, eIF4G was cleaved by expression of the poliovirus 2A protease (2Apro) and the alpha subunit of eIF2 was inactivated by phosphorylation induced by arsenite treatment. Moreover, cellular location of these and other translation components was analyzed in BHK infected cells by confocal microscopy. Cleavage of eIF4G by poliovirus 2Apro does not hamper translation of subgenomic mRNA in SV infected cells, but bisection of this factor blocks subgenomic mRNA translation in uninfected cells or in cell-free systems. SV infection induces phosphorylation of eIF2α, a process that is increased by arsenite treatment. Under these conditions, translation of subgenomic mRNA occurs to almost the same extent as controls in the infected cells but is drastically inhibited in uninfected cells. Notably, the correct initiation site on the subgenomic mRNA is still partially recognized when the initiation codon AUG is modified to other codons only in infected cells. Finally, immunolocalization of different eIFs reveals that eIF2 α and eIF4G are excluded from the foci, where viral RNA replication occurs, while eIF3, eEF2 and ribosomes concentrate in these regions. These findings support the notion that canonical initiation takes place when the subgenomic mRNA is translated out of the infection context, while initiation can occur without some eIFs and even at non-AUG codons in infected cells