Theoretical predictions of a bucky-diamond SiC cluster

A study of structural relaxations of Si(n)C(m) clusters corresponding to different compositions, different relative arrangements of Si/C atoms, and different types of initial structure, reveals that the Si(n)C(m) bucky-diamond structure can be obtained for an initial network structure constructed from a truncated bulk 3C-SiC for a magic composition corresponding to n?=?68 and m?=?79. This study was performed using a semi-empirical Hamiltonian (SCED-LCAO) since it allowed an extensive search of different types of initial structures. However, the bucky-diamond structure predicted by this method was also confirmed by a more accurate density functional theory (DFT) based method. The bucky-diamond structure exhibited by a SiC-based system represents an interesting paradigm where a Si atom can form three-coordinated as well as four-coordinated networks with carbon atoms and vice versa and with both types of network co-existing in the same structure. Specifically, the bucky-diamond structure of the Si(68)C(79) cluster consists of a 35-atom diamond-like inner core (four-atom coordinations) suspended inside a 112-atom fullerene-like shell (three-atom coordinations).     

Design of Six Element MIMO Antenna with Enhanced Gain for 28/38 GHz mm-Wave 5G Wireless Application

The fifth-generation (5G) wireless technology is the most recent standardization in communication services of interest across the globe. The concept of Multiple-Input-Multiple-Output antenna (MIMO) systems has recently been incorporated to operate at higher frequencies without limitations. This paper addresses, design of a high-gain MIMO antenna that offers a bandwidth of 400 MHz and 2.58 GHz by resonating at 28 and 38 GHz, respectively for 5G millimeter (mm)-wave applications. The proposed design is developed on a RT Duroid 5880 substrate with a single elemental dimension of 9.53 × 7.85 × 0.8 mm³. The patch antenna is fully grounded and is fed with a 50-ohm stepped impedance microstrip line. It also has an I-shaped slot and two electromagnetically coupled parasitic slotted components. This design is initially constructed as a single-element structure and proceeded to a six-element MIMO antenna configuration with overall dimensions of 50 × 35 × 0.8 mm³. The simulated prototype is fabricated and measured for analyzing its performance characteristics, along with MIMO antenna diversity performance factors making the proposed antenna suitable for 5G mm-wave and 5G-operated handheld devices.     

A Simulation Approach to Study the Effect of SiC Polytypism Factor on Sensitivity of Piezoresistive MEMS Pressure Sensor

Silicon - SiC is a well known wide band gap semiconductor explored for realizing the piezoresistive micro-electro-mechanical systems (MEMS) pressure sensors for harsh environments. In this work a...     

Restless leg syndrome presenting as chronic severe limb pain in a dialysis patient

“Chronic pain” is a commonly reported symptom among hemodialysis patients. Despite its high prevalence and the poor health-related quality of life associated with it, chronic pain remains an ineffectively assessed and managed entity in dialysis patients. We report a case of a 55-year-old gentleman on maintenance hemodialysis who presented with 3 months history of “excruciating flitting and fleeting type” of pain largely involving both lower limbs and occasionally neck, shoulder, chest, and upper limbs. The pain was so intolerable that it even triggered suicidal intentions in the patient. Common causes of chronic pain in dialysis patients were considered, but the initial history and clinical examination remained elusive. The patient was empirically started on oral analgesics, benzodiazepines, calcitriol, and levocarnitine supplementation but had no significant effect on his symptoms. A comprehensive repeat clinical history revealed the nocturnal periodicity of symptoms, specific aggravation of pain with inactivity, and its temporary relief with movement. This helped us narrow down the diagnosis to restless leg syndrome (RLS) amidst the myriad causes of chronic pain in dialysis patients. The “constant urge to move the legs” which is the defining characteristic of RLS was inconspicuous in our patient and excruciating pain was the predominant manifestation. This atypical presentation of RLS with agonizing pain involving multiple sites of the body led to a delay in the diagnosis and initiation of appropriate therapeutic measures. The patient had a dramatic response to therapy with dopamine agonists and withdrawal of the drug led to reappearance of his symptoms which further confirmed the diagnosis of RLS. RLS should be considered in the evaluation of chronic pain in dialysis patients and renal health care providers should familiarize themselves with the varied atypical, forme fruste manifestations of RLS to avoid diagnostic delay of this disabling but treatable condition.     

A Novel Soft Clustering Approach for Gene Expression Data

Gene expression data represents a condition matrix where each row represents the gene and the column shows the condition. Micro array used to detect gene expression in lab for thousands of gene at a time. Genes encode proteins which in turn will dictate the cell function. The production of messenger RNA along with processing the same are the two main stages involved in the process of gene expression. The biological networks complexity added with the volume of data containing imprecision and outliers increases the challenges in dealing with them. Clustering methods are hence essential to identify the patterns present in massive gene data. Many techniques involve hierarchical, partitioning, grid based, density based, model based and soft clustering approaches for dealing with the gene expression data. Understanding the gene regulation and other useful information from this data can be possible only through effective clustering algorithms. Though many methods are discussed in the literature, we concentrate on providing a soft clustering approach for analyzing the gene expression data. The population elements are grouped based on the fuzziness principle and a degree of membership is assigned to all the elements. An improved Fuzzy clustering by Local Approximation of Memberships (FLAME) is proposed in this work which overcomes the limitations of the other approaches while dealing with the non-linear relationships and provide better segregation of biological functions.     

Analysis of two-stage address coding scheme for FFH/MFSK systemsover Rician fading channels

The author investigates the effect of fade distributions on various FH/MFSK systems, and subsequently provides a fair comparison between the performance of the dual FH/MFSK system proposed by Park and Lee (1996) with that of the conventional system suggested by Goodman et al. (1980)     

On adaptive go-back-N ARQ protocol for variable-error rate channels

This letter presents a simple method to simultaneously optimize a multiplicity of design parameters for the adaptive automatic repeat request strategy previously reported, and subsequently provides a quantitative measurement that reflects the appropriateness of the selected parameters. An exact analytical expression that allows us to compute the throughput crossover probability between the two different protocols is derived. The results provide fundamental insights into how these key parameters interact and determine the system performance     

Analysis of Generalized Selection Diversity Systems in Wireless Channels

Motivated by practical considerations in the design of low-complexity receiver structures for wideband cellular code division multiple access, millimeter wave, and ultrawideband communications, the study on the generalized selection combining (GSC) receiver that adaptively combines a subset of M "strongest" paths out of L available paths has intensified over the past few years. This paper derives concise analytical expressions for the moment generating function (MGF) of the GSC(M,L) output signal-to-noise ratio when the fading statistics are independent and identically distributed. The novelty of this mathematical framework in computing the MGF relies on the fact that it allows all common multipath fading channel models (Rayleigh, Rician, Nakagami-m, and Nakagami-q) to be treated in a unified sense. It also leads to a much more computationally efficient formula than those available in the literature and is valid for any combinations of M and L values. Using these newly derived MGFs, a unified error probability analysis for many coherent and noncoherent digital-modulation/detection schemes in a myriad of fading environments was provided     

Analysis of equal gain diversity receivers in correlated Rayleigh fading channels

Utilizing a desirable exponential integral representation of Gaussian probability integral, this letter derives the average bit error rate (ABER) expressions for coherent binary signals that employ a dual branch equal gain combining receiver. Our numerical results reveal that the branch correlations do not affect the ABER significantly provided power correlation coefficient is less than 0.3 in Rayleigh fading.     

Ergodic capacity analysis of cooperative amplify‐and‐forward relay networks over generalized fading channels

This paper presents two new methods for evaluating the ergodic channel capacities of cooperative non‐regenerative multirelay networks in a myriad of fading environments and under three distinct source‐adaptive transmission policies: (i) optimal rate adaptation with a fixed transmit power; (ii) optimal joint power‐and‐rate adaptation; and (iii) truncated channel inversion with fixed rate. In contrast to the previous related works, our proposed unified analytical frameworks that are based on the moment generating function and/or the cumulative distribution function of end‐to‐end signal‐to‐noise ratio allow us to gain insights into how power assignment during different transmission phases, relay node placement, fade distributions, and dissimilar fading statistics across the distinct communication links impact the ergodic capacity, without imposing any restrictions on the channel fading parameters. Copyright © 2013 John Wiley & Sons, Ltd.