Superconductivity and Electronic Structure of Perovskite MgCNi3

The electronic structure, stability, electron phonon coupling and superconductivity of the non-oxide perovskite MgCNi$_3$ are studied using density functional calculations. The band structure is dominated by a Ni $d$ derived density of states peak just below the Fermi energy, which leads to a moderate Stoner enhancement, placing MgCNi$_3$ in the range where spin fluctuations may noticeably affect transport, specific heat and superconductivity, providing a mechanism for reconciling various measures of the coupling $\lambda$. Strong electron phonon interactions are found for the octahedral rotation mode and may exist for other bond angle bending modes. The Fermi surface contains nearly cancelling hole and electron sheets that give unusual behavior of transport quantities particularly the thermopower. The results are discussed in relation to the superconductivity of MgCNi$_3$.Comment: 4 pages, RevTex, 5 ps figure

Theoretical search for Chevrel phase based thermoelectric materials

We investigate the thermoelectric properties of some semiconducting Chevrel phases. Band structure calculations are used to compute thermopowers and to estimate of the effects of alloying and disorder on carrier mobility. Alloying on the Mo site with transition metals like Re, Ru or Tc to reach a semiconducting composition causes large changes in the electronic structure at the Fermi level. Such alloys are expected to have low carrier mobilities. Filling with transition metals was also found to be incompatible with high thermoelectric performance based on the calculated electronic structures. Filling with Zn, Cu, and especially with Li was found to be favorable. The calculated electronic structures of these filled Chevrel phases are consistent with low scattering of carriers by defects associated with the filling. We expect good mobility and high thermopower in materials with the composition close to (Li,Cu)$_4$Mo$_6$Se$_8$, particularly when Li-rich, and recommend this system for experimental investigation.Comment: 4 two-column pages, 4 embedded ps figure

Specific heat study of the Na(0.3)CoO(2).1.3H(2)O superconductor: influence of the complex chemistry

We report results of specific heat measurements on polycrystalline samples of the layered superconductor, Na(0.3)CoO(2).1.3H(2)O. The electronic contribution to the specific heat, gamma, is found to be 12.2 mJ/mol-K2. The feature at the superconducting transition is rather sharp, becoming broad and strongly suppressed in an applied magnetic field. The data indicate a residual normal state electronic specific heat at low temperatures, implying that there is a sizable population of normal state electrons in the samples even below Tc. Inhomogeneity in the Na content, to which the superconducting state is exquisitely sensitive, appears to be the most likely explanation for these results. These results further indicate that special sample handling is required for an accurate characterization of the superconducting state in this material.Comment: publication information adde

A Capital Adequacy Buffer Model

__Abstract__ In this paper, we develop a new capital adequacy buffer model (CABM) which is sensitive to dynamic economic circumstances. The model, which measures additional bank capital required to compensate for fluctuating credit risk, is a novel combination of the Merton structural model which measures distance to default and the timeless capital asset pricing model (CAPM) which measures additional returns to compensate for additional share price risk

Nonparametric Multiple Change Point Analysis of the Global Financial Crisis

This paper presents an application of a recently developed approach by Matteson and James (2012) for the analysis of change points in a data set, namely major financial market indices converted to financial return series. The general problem concerns the inference of a change in the distribution of a set of time-ordered variables. The approach involves the nonparametric estimation of both the number of change points and the positions at which they occur. The approach is general and does not involve assumptions about the nature of the distributions involved or the type of change beyond the assumption of the existence of the α absolute moment, for some α ε (0,2). The estimation procedure is based on hierarchical clustering and the application of both divisive and agglomerative algorithms. The method is used to evaluate the impact of the Global Financial Crisis (GFC) on the US, French, German, UK, Japanese and Chinese markets, as represented by the S&P500, CAC, DAX, FTSE All Share, Nikkei 225 and Shanghai A share Indices, respectively, from 2003 to 2013. The approach is used to explore the timing and number of change points in the datasets corresponding to the GFC and subsequent European Debt Crisis

An Independently Tunable Tri-band Antenna Design for Concurrent Multi-band Single Chain Radio Receivers

In this paper, a novel tunable tri-band antenna is presented for concurrent, multi-band, single chain radio receivers. The antenna is manufactured on a 50×100 mm FR4 printed circuit board (PCB), and is able to provide three concurrent, independently tunable operating bands covering a frequency range from 600 MHz to 2.7 GHz. The antenna performance is investigated for both numerical and experimental methods when using, first, varactor diodes and, second, digitally tunable capacitors (DTCs) to tune frequencies, which shows the antenna gain can be improved by up to 2.6 dBi by using DTCs. A hardware-in-the-loop test-bed provides a system level evaluation of the proposed antenna in a direct RF digitized, concurrent, tri-band radio receiver. By measuring the receiver’s error vector magnitude, we demonstrate sufficient isolation between concurrent bands achieving 30 MHz of aggregated bandwidth as well as strong resilience to adjacent blockers next to each band. The data reported in this article are available from the ORDA digital repository (https://doi.org/10.15131/shef.data.5346295)

Concurrent, Multi-band, Single-Chain Radio Receiver for High Data-Rate HetNets

A concurrent, tunable, triple-band, single chain radio receiver for 5G radio access networks is presented and its performance is evaluated in a hardware-in-the-loop test-bed. The test-bed emulates a 5G heterogeneous network supporting three independently tunable, wideband, simultaneous connections over a frequency range from 600 MHz to 2.7 GHz. The single chain receiver is able to achieve an aggregate bandwidth of 93.75 MHz, 31.25 MHz per band, and a net data rate of 187.5 Mbit/s through the use of single-carrier QPSK transmissions. The receiver demonstrate sufficient isolation between the concurrent transmissions as well as strong resilience to adjacent blockers through the use of a small guard band

Role of MMP-2, MMP-9 and VEGF as serum biomarker in early prognosis of renal cell carcinoma

Introduction: Renal cell carcinoma epitomizes a diversified group of tumors which contributes more than 15,000 deaths annually worldwide. In spite of tremendous efforts to identify prognostic factors apart from grade, histology and tumor size, they are not so obvious yet to fulfill the requirement. In this study, the prognostic role of serum matrix metalloproteinase (MMP)-2, 9, and vascular endothelial growth factor (VEGF) levels in patients with pre and postoperative renal cell carcinoma are evaluated to use as biomarker.Patients and methods: A total of 100 patients with a diagnosis of renal cell carcinoma included in the study. Additionally, hundred healthy kidney donors enrolled as control, serum MMP-2, MMP-9, and VEGF levels were analyzed in the serum of post and preoperative patients and parallel in control serum samples by ELISA method.Result: Most of the patients with RCC were found to have high concentrations of serum MMP-2, MMP-9, and VEGF. The levels of MMP-2 in the serum of preoperative patients ranged from 627 to 1117 ng/ml (833.90 ± 111.91), postoperative MMP-2 range 302–913 (553.02 ± 150.08), control range 122–384 (228.33 ± 72.52). In MMP-9 pre-operative range 619–1233 (862.32 ± 119.77), post-operative range 124–909 (552.88 ± 151.91) and control range 42–467 (245.44 ± 116.52 and in VEGF preoperative range was 0.792–2.214 (1.35 ± 0.36), postoperative range was 0.315–1.917 (0.81 ± 0.46) and in control it was 0.01–0.39 (0.10 ± 0.09). We observed that preoperative levels of all three markers, were significantly increased if compared with postoperative and control levels (P = 0.001) however, no any significant correlation found when the levels correlated with grade, stage, size, and type for MMP-2 and MMP-9, but VEGF shows some significance in comparison

Tubular solid oxide fuel cell developments

An overview of the tubular solid oxide fuel cell (SOFC) development at Westinghouse is presented in this paper. The basic operating principles of SOFCs, evolution in tubular cell design and performance improvement, selection criteria for cell component materials, and cell processing techniques are discussed. The commercial goal is to develop a cell that can operate for 5 to 10 years. Results of cell test operated for more than 50,000 hours are presented. Since 1986, significant progress has been made in the evolution of cells with higher power, lower cost and improved thermal cyclic capability. Also in this period, successively larger multi-kilowatt electrical generators systems have been built and successfully operated for more than 7000 hours