Temperature dependent negative capacitance behavior in (Ni/Au)/AlGaN/AIN/GaN heterostructures

Cataloged from PDF version of article.The temperature dependent capacitance voltage (C-V) and conductance voltage (G/omega-V) characteristics of (Ni/Au)/Al(0.22)Ga(0.78)N/AlN/GaN heterostructures were investigated by considering the series resistance (R(s)) effect in the temperature range of 80-390 K. The experimental results show that the values of C and G/omega are strongly functioning of temperature and bias voltage. The values of C cross at a certain forward bias voltage point (similar to 2.8 V) and then change to negative values for each temperature, which is known as negative capacitance (NC) behavior. In order to explain the NC behavior, we drawn the C vs I and G/omega vs I plots for various temperatures at the same bias voltage. The negativity of the C decreases with increasing temperature at the forward bias voltage, and this decrement in the NC corresponds to the increment of the conductance. When the temperature was increased, the value of C decreased and the intersection point shifted towards the zero bias direction. This behavior of the C and G/omega values can be attributed to an increase in the polarization and the introduction of more carriers in the structure. R(s) values increase with increasing temperature. Such temperature dependence is in obvious disagreement with the negative temperature coefficient of R or G reported in the literature. The intersection behavior of C-V curves and the increase in R(s) with temperature can be explained by the lack of free charge carriers, especially at low temperatures. (C) 2010 Elsevier B.V. All rights reserve

Association between mean platelet volume levels and inflammation in SLE patients presented with arthritis

Background: Systemic lupus erythematosus (SLE) may be characterized by periods of remissions and chronic or acute relapses. The complexity of clinical presentation of the SLE patients leads to incorrect evaluation of disease activity. Mean platelet volume (MPV) has been studied as a simple inflammatory marker in several diseases. There is no study in the literature about MPV levels in adult SLE patients with arthritis.Objectives: We aimed to investigate the MPV levels in the SLE population with arthritis during and between activations.Methods: The study consisted of 44 SLE patients with arthritis in activation period (Group 1), the same 44 SLE patients with arthritis in remission period (Group 2) and 44 healthy controls (Group 3). Erythrocyte sedimentation rate (ESR), creactive protein (CRP), white blood cell count, platelet count, and mean platelet volume (MPV) levels were retrospectively recorded from patient files.Results: The mean ages of the SLE subjects were 42 ± 16 years, while the mean ages of controls was 41 ± 17 years. MPV was significantly lower in Group 1(7.66±0.89fL) than in Group 2 (8.61±1.06 fL) and Group 3(8.62±1.11fL) (p<0.0001). The differences between groups reached statistical significance.Conclusions: We suggest that MPV levels decrease in patients with arthritis of SLE activation when compared to the same patients in remission and healthy controls.Key words: Systemic lupus erythematosus, Arthritis, Mean platelet volum

Infection by agnoprotein-negative mutants of polyomavirus JC and SV40 results in the release of virions that are mostly deficient in DNA content

<p>Abstract</p> <p>Background</p> <p>Human polyomavirus JC (JCV) is the etiologic agent of a brain disease, known as progressive multifocal leukoencephalopathy (PML). The JCV genome encodes a small multifunctional phospho-protein, agnoprotein, from the late coding region of the virus, whose regulatory functions in viral replication cycle remain elusive. In this work, the functional role of JCV and SV40 agnoproteins in virion release was investigated using a point mutant (Pt) of each virus, where the ATG codon of agnoprotein was mutated to abrogate its expression.</p> <p>Results</p> <p>Analysis of both viral protein expression and replication using Pt mutant of each virus revealed that both processes were substantially down-regulated in the absence of agnoprotein compared to wild-type (WT) virus. Complementation studies in cells, which are constitutively expressing JCV agnoprotein and transfected with the JCV Pt mutant genome, showed an elevation in the level of viral DNA replication near to that observed for WT. Constitutive expression of large T antigen was found to be not sufficient to compensate the loss of agnoprotein for efficient replication of neither JCV nor SV40 in vivo. Examination of the viral release process for both JCV and SV40 Pt mutants showed that viral particles are efficiently released from the infected cells in the absence of agnoprotein but were found to be mostly deficient in viral DNA content.</p> <p>Conclusions</p> <p>The results of this study provide evidence that agnoprotein plays an important role in the polyomavirus JC and SV40 life cycle. Infection by agnoprotein-negative mutants of both viruses results in the release of virions that are mostly deficient in DNA content.</p

iRsp1095: A genome-scale reconstruction of the Rhodobacter sphaeroides metabolic network

<p>Abstract</p> <p>Background</p> <p><it>Rhodobacter sphaeroides </it>is one of the best studied purple non-sulfur photosynthetic bacteria and serves as an excellent model for the study of photosynthesis and the metabolic capabilities of this and related facultative organisms. The ability of <it>R. sphaeroides </it>to produce hydrogen (H₂), polyhydroxybutyrate (PHB) or other hydrocarbons, as well as its ability to utilize atmospheric carbon dioxide (CO₂) as a carbon source under defined conditions, make it an excellent candidate for use in a wide variety of biotechnological applications. A genome-level understanding of its metabolic capabilities should help realize this biotechnological potential.</p> <p>Results</p> <p>Here we present a genome-scale metabolic network model for <it>R. sphaeroides </it>strain 2.4.1, designated iRsp1095, consisting of 1,095 genes, 796 metabolites and 1158 reactions, including <it>R. sphaeroides</it>-specific biomass reactions developed in this study. Constraint-based analysis showed that iRsp1095 agreed well with experimental observations when modeling growth under respiratory and phototrophic conditions. Genes essential for phototrophic growth were predicted by single gene deletion analysis. During pathway-level analyses of <it>R. sphaeroides </it>metabolism, an alternative route for CO₂assimilation was identified. Evaluation of photoheterotrophic H₂production using iRsp1095 indicated that maximal yield would be obtained from growing cells, with this predicted maximum ~50% higher than that observed experimentally from wild type cells. Competing pathways that might prevent the achievement of this theoretical maximum were identified to guide future genetic studies.</p> <p>Conclusions</p> <p>iRsp1095 provides a robust framework for future metabolic engineering efforts to optimize the solar- and nutrient-powered production of biofuels and other valuable products by <it>R. sphaeroides </it>and closely related organisms.</p

Keynote Lecture – The Interplay of Multiple Hazards and Urban Development: The context of Istanbul

Tomorrow’s Cities is the UK Research and Innovation (UKRI) Global Challenges Research Fund (GCRF) Urban Disaster Risk Hub – an interdisciplinary research hub with the aim to catalyse a transition from crisis management to multi-hazard risk-informed and inclusive planning in four cities in low-and-middle income countries. Istanbul in Turkey is one of the four cities investigated. It is one of the largest urban agglomerations in Europe where more than 15 million people reside in more than 1 million buildings. Considering that the population was 4.75 million in 1980, Istanbul’s urban sprawl was inevitable. Due to an imbalance between the population growth and housing supply, Istanbul’s urbanization was shaped by illegal construction processes producing the gecekondus in almost every part of the city (Gencer and Mentese, 2016). Unplanned urban expansion was so rapid that the urban master plan of 1980, which set the limits and strategies for urban development, became completely invalid by 1989 (Tapan, 1998). This situation led to the development of a new urban master plan in 1994 that included geoscientific analysis, and which highlighted the possibility of losses due to an earthquake on the segments of the North Anatolian Fault in the Marmara Sea. Uncontrolled and unplanned development continued in Istanbul until 1999 when two major earthquakes hit the region causing at least 18.000 deaths and $16 billion economic loss. These events changed the authorities’ perspective to earthquake risk and its mitigation. As a result, the 1998 earthquake resistant design code (published one year before the 1999 earthquakes) was widely embraced and implemented. Furthermore, several urban transformation projects have taken place in the last 20 years for reducing disaster risk. These have had varied success, with research to date showing that areas selected for urban transformation were often chosen on the basis of land value rather than hazard risk, and that a pro-poor approach is missing. Despite these efforts, Istanbul’s earthquake risk remains high. Furthermore, recent urban development plans are seeing the city expand into undeveloped lands to the west, increasing exposure to new hazards, namely flash flooding and landslides. The combined impact of these hazards is not evenly distributed, and the associated risks are heightened by poor infrastructural resilience and social vulnerabilities. Therefore, it is crucial to integrate different types of hazards and risks into the urban development context for future scenarios, so that a physically and socio-economically safer development that prioritizes the wellbeing of local communities can be facilitated. This presentation summarises the research conducted in Istanbul over the first 18 months of the Tomorrow’s Cities Project by a consortium of Turkish and UK researchers. This research spans the better characterisation of earthquake and landslide hazards, development of analysis methods for predicting the response of case study buildings to multiple hazards and a Bayesian network based approach for assessing road infrastructure resilience under multiple hazard scenarios. Furthermore, plans for building a Resilient Urban Development Decision Support Environment (RUD-DSE) for communicating the relevance of this research on future urban planning is described

Case report – ancient schwannoma of the scrotum

BACKGROUND: Scrotal schwannoma is a rare neoplasm and poses a diagnostic challenge to urologists. This article describes a rare case of ancient scrotal schwannoma and reviews the current modality of investigation and treatment of this tumour. CASE REPORT: A 28 year old man presented with a 3-month history of an asymptomatic scrotal swelling. Ultrasonography and computer topography revealed an intra-scrotal and extra-testicular mass without local invasion. Surgical excision was undertaken and histology was an ancient schwannoma of the scrotum. CONCLUSION: Schwannoma is a benign encapsulating neoplasm with an overall low incidence, occurring mostly in the head and neck region and seldom in the scrotum. Histology shows two distinctive patterns, Antoni type A and B areas. Variations of schwannoma such as cellular, ancient, glandular and epithelioid are observed based on the appearances. Ancient schwannoma exhibits pleomorphism without mitosis as the result of cellular degeneration, which can lead to an erroneous diagnosis of malignancy. Imaging modalities are non-specific for schwannomas, but can define tumour size, site and extension. The mainstay treatment is complete excision, although local recurrence may occur in large and incompletely excised lesions. Malignant change is exceedingly rare

Hypoxia induces dilated cardiomyopathy in the chick embryo: mechanism, intervention, and long-term consequences

Background: Intrauterine growth restriction is associated with an increased future risk for developing cardiovascular diseases. Hypoxia in utero is a common clinical cause of fetal growth restriction. We have previously shown that chronic hypoxia alters cardiovascular development in chick embryos. The aim of this study was to further characterize cardiac disease in hypoxic chick embryos. Methods: Chick embryos were exposed to hypoxia and cardiac structure was examined by histological methods one day prior to hatching (E20) and at adulthood. Cardiac function was assessed in vivo by echocardiography and ex vivo by contractility measurements in isolated heart muscle bundles and isolated cardiomyocytes. Chick embryos were exposed to vascular endothelial growth factor (VEGF) and its scavenger soluble VEGF receptor-1 (sFlt-1) to investigate the potential role of this hypoxia-regulated cytokine. Principal Findings: Growth restricted hypoxic chick embryos showed cardiomyopathy as evidenced by left ventricular (LV) dilatation, reduced ventricular wall mass and increased apoptosis. Hypoxic hearts displayed pump dysfunction with decreased LV ejection fractions, accompanied by signs of diastolic dysfunction. Cardiomyopathy caused by hypoxia persisted into adulthood. Hypoxic embryonic hearts showed increases in VEGF expression. Systemic administration of rhVEGF165 to normoxic chick embryos resulted in LV dilatation and a dose-dependent loss of LV wall mass. Lowering VEGF levels in hypoxic embryonic chick hearts by systemic administration of sFlt-1 yielded an almost complete normalization of the phenotype. Conclusions/Significance: Our data show that hypoxia causes a decreased cardiac performance and cardiomyopathy in chick embryos, involving a significant VEGF-mediated component. This cardiomyopathy persists into adulthood

Analysis of Error-Correcting Codes for Lattice-Based Key Exchange

Lattice problems allow the construction of very efficient key exchange and public-key encryption schemes. When using the Learning with Errors (LWE) or Ring-LWE (RLWE) problem such schemes exhibit an interesting trade-off between decryption error rate and security. The reason is that secret and error distributions with a larger standard deviation lead to better security but also increase the chance of decryption failures. As a consequence, various message/key encoding or reconciliation techniques have been proposed that usually encode one payload bit into several coefficients. In this work, we analyze how error-correcting codes can be used to enhance the error resilience of protocols like NewHope, Frodo, or Kyber. For our case study, we focus on the recently introduced NewHope Simple and propose and analyze four different options for error correction: i) BCH code; ii) combination of BCH code and additive threshold encoding; iii) LDPC code; and iv) combination of BCH and LDPC code. We show that lattice-based cryptography can profit from classical and modern codes by combining BCH and LDPC codes. This way we achieve quasi-error-free communication and an increase of the estimated post-quantum bit-security level by 20.39% and a decrease of the communication overhead by 12.8%