Spectroscopic evidence of odd frequency superconducting order

Spin filter superconducting S/I/N tunnel junctions (NbN/GdN/TiN) show a robust and pronounced zero bias conductance peak at low temperatures, the magnitude of which is several times the normal state conductance of the junction. Such a conductance anomaly is representative of unconventional superconductivity and is interpreted as a direct signature of an odd frequency superconducting order.Comment: 5 pages, 3 figures + supplementary informatio

Reverse engineering synthetic antiviral amyloids

Human amyloids have been shown to interact with viruses and interfere with viral replication. Based on this observation, we employed a synthetic biology approach in which we engineered virus-specific amyloids against influenza A and Zika proteins. Each amyloid shares a homologous aggregation-prone fragment with a specific viral target protein. For influenza we demonstrate that a designer amyloid against PB2 accumulates in influenza A-infected tissue in vivo. Moreover, this amyloid acts specifically against influenza A and its common PB2 polymorphisms, but not influenza B, which lacks the homologous fragment. Our model amyloid demonstrates that the sequence specificity of amyloid interactions has the capacity to tune amyloid-virus interactions while allowing for the flexibility to maintain activity on evolutionary diverging variants. Some human amyloid proteins have been shown to interact with viral proteins, suggesting that they may have potential as therapeutic agents. Here the authors design synthetic amyloids specific for influenza A and Zika virus proteins, respectively, and show that they can inhibit viral replication

Computer-aided characterisation of solar cell from a single illuminated current(I)-voltage(V) curve

A computer aided characterization technique has been proposed to calculate the five parameters of a solar cell represented by one diode model. The nonlinear I-V relation is linearized by Taylor series expansion. The cell parameters Iph, I,, A, R, and Rsh are obtained by solving five analytical expressions simultaneously. The influence of fixing the values to these parameters on the I-V charccteristics has been studie

A survey of error-correction methods for next-generation sequencing

Error Correction is important for most next-generation sequencing applications because highly accurate sequenced reads will likely lead to higher quality results. Many techniques for error correction of sequencing data from next-gen platforms have been developed in the recent years. However, compared with the fast development of sequencing technologies, there is a lack of standardized evaluation procedure for different error-correction methods, making it difficult to assess their relative merits and demerits. In this article, we provide a comprehensive review of many error-correction methods, and establish a common set of benchmark data and evaluation criteria to provide a comparative assessment. We present experimental results on quality, run-time, memory usage and scalability of several error-correction methods. Apart from providing explicit recommendations useful to practitioners, the review serves to identify the current state of the art and promising directions for future research. Availability: All error-correction programs used in this article are downloaded from hosting websites. The evaluation tool kit is publicly available at: http://aluru-sun.ece.iastate.edu/doku.php?id=ecr

Generalized Spatial Modulation in Indoor Wireless Visible Light Communication

In this paper, we investigate the performance of generalized spatial modulation (GSM) in indoor wireless visible light communication (VLC) systems. GSM uses N-t light emitting diodes (LED), but activates only N-a of them at a given time. Spatial modulation and spatial multiplexing are special cases of GSM with N-a = 1 and N-a = N-t, respectively. We first derive an analytical upper bound on the bit error rate (BER) for maximum likelihood (ML) detection of GSM in VLC systems. Analysis and simulation results show that the derived upper bound is very tight at medium to high signal-to-noise ratios (SNR). The channel gains and channel correlations influence the GSM performance such that the best BER is achieved at an optimum LED spacing. Also, for a fixed transmission efficiency, the performance of GSM in VLC improves as the half-power semi-angle of the LEDs is decreased. We then compare the performance of GSM in VLC systems with those of other MIMO schemes such as spatial multiplexing (SMP), space shift keying (SSK), generalized space shift keying (GSSK), and spatial modulation (SM). Analysis and simulation results show that GSM in VLC outperforms the other considered MIMO schemes at moderate to high SNRs; for example, for 8 bits per channel use, GSM outperforms SMP and GSSK by about 21 dB, and SM by about 10 dB at 10(-4) BER

Coded Index Modulation for Non-DC-Biased OFDM in Multiple LED Visible Light Communication

Use of multiple light emitting diodes (LED) is an attractive way to increase spectral efficiency in visible light communications (VLC). A non-DC-biased OFDM (NDC OFDM) scheme that uses two LEDs has been proposed in the literature recently. NDC OFDM has been shown to perform better than other OFDM schemes for VLC like DC-biased OFDM (DCO OFDM) and asymmetrically clipped OFDM (ACO OFDM) in multiple LEDs settings. In this paper, we propose an efficient multiple LED OFDM scheme for VLC which uses coded index modulation. The proposed scheme uses two transmitter blocks, each having a pair of LEDs. Within each block, NDC OFDM signaling is done. The selection of which block is activated in a signaling interval is decided by information bits (i.e., index bits). In order to improve the reliability of the index bits at the receiver (which is critical because of high channel correlation in multiple LEDs settings), we propose to use coding on the index bits alone. We call the proposed scheme as CI-NDC OFDM (coded index NDC OFDM) scheme. We present the performance results of CI-NDC OFDM scheme with the index bits coded by (i) LDPC and (ii) Walsh-Hadamard codes. Simulation results show that, for the same spectral efficiency, CI-NDC OFDM that uses coding on the index bits performs better than NDC OFDM

ALFRED: A Practical Method for Alignment-Free Distance Computation

Alignment-free approaches are gaining persistent interest in many sequence analysis applications such as phylogenetic inference and metagenomic classification/clustering, especially for large-scale sequence datasets. Besides the widely used k-mer methods, the average common substring (ACS) approach has emerged to be one of the well-known alignment-free approaches. Two recent works further generalize this ACS approach by allowing a bounded number k of mismatches in the common substrings, relying on approximation (linear time) and exact computation, respectively. Albeit having a good worst-case time complexity O(n log(k) n), the exact approach is complex and unlikely to be efficient in practice. Herein, we present ALFRED, an alignment-free distance computation method, which solves the generalized common substring search problem via exact computation. Compared to the theoretical approach, our algorithm is easier to implement and more practical to use, while still providing highly competitive theoretical performances with an expected run-time of O(n logk n). By applying our program to phylogenetic inference as a case study, we find that our program facilitates to exactly reconstruct the topology of the reference phylogenetic tree for a set of 27 primate mitochondrial genomes, at reasonably acceptable speed. ALFRED is implemented in C++ programming language and the source code is freely available online

Equipartition of Current in Parallel Conductors on Cooling Through the Superconducting Transition

Our experiments show that for two or more pieces of different lengths of a wire combined in parallel and connected to a dc source, the current ratio evolves towards unity as the combination is cooled to the superconducting transition temperature Tc, and remains pinned at that value below it. This equipartition of the total current is a surprise, but can be understood in terms of the progressive depression of superconducting fluctuations in the transition region due to the transport current. This equipartition without fine tuning is derived analytically from the Onsager-Rayleigh least dissipation principle governing the self organization (redistribution) of the current

Studies on ac losses in Bi2Sr2CaCu2O8Bi_2Sr_2CaCu_2O_8 single crystals

Using a novel technique of measuring absolute ac losses at radio frequencies, the temperature, magnetic field and angle dependence of rf losses in superconducting single crystals of $Bi_2Sr_2CaCu_2O_8$ is studied. An unexpected, larger than normal state ac loss is observed below $T_c$. We provide an explanation for this observation in terms of the energy required to decouple the intrinsic Josephson junctions in the crystals. The studies are carried out both at zero magnetic field and at different values of magnetic fields applied at different angles θ between the field and the c-axis of the crystal. We observe two maxima in ac loss as a function of temperature. The amplitude, width and the position of the first maximum (peak A) change with the magnitude and orientation of the applied magnetic field. These results are discussed in terms of the critical current density of the Josephson junctions, which decreases with the increasing field and changes with the orientation. The second maximum (peak B) appears just below $T_c$ only in the presence of the magnetic field and has been attributed to the vortex motion. The amplitude of this peak as well changes with the magnetic field and with the angle of orientation. The analysis shows that the loss is due to pancake vortices

Angular dependence of direct rf power absorption studies in Bi2Sr2CaCu2O8Bi_{2}Sr_{2}CaCu_{2}O_{8} single crystals

We have studied rf power dissipation in $Bi_{2}Sr_{2}CaCu_{2}O_{8}$ single crystals as a function of angle \Theta between the applied field and c-axis of the crystal by using a novel technique of measuring direct rf power absorption. We observed two peaks in power absorption as a function of temperature. The amplitude and position of the first peak (peak A) change with orientation and attributed to Josephson junctions decoupling. The second peak (peak B) appears just below $T_{c}$ has been attributed to the vortex motion and its amplitude depends on the angle of orientation