Sparse Array DFT Beamformers for Wideband Sources

Sparse arrays are popular for performance optimization while keeping the hardware and computational costs down. In this paper, we consider sparse arrays design method for wideband source operating in a wideband jamming environment. Maximizing the signal-to-interference plus noise ratio (MaxSINR) is adopted as an optimization objective for wideband beamforming. Sparse array design problem is formulated in the DFT domain to process the source as parallel narrowband sources. The problem is formulated as quadratically constraint quadratic program (QCQP) alongside the weighted mixed $l_{1-\infty}$-norm squared penalization of the beamformer weight vector. The semidefinite relaxation (SDR) of QCQP promotes sparse solutions by iteratively re-weighting beamformer based on previous iteration. It is shown that the DFT approach reduces the computational cost considerably as compared to the delay line approach, while efficiently utilizing the degrees of freedom to harness the maximum output SINR offered by the given array aperture

Quantum phase communication channels assisted by non-deterministic noiseless amplifiers

We address quantum $M$-ary phase-shift keyed (PSK) communication channels in the presence of phase diffusion, and analyze the use of probabilistic noiseless linear amplifiers (NLA) to enhance performance of coherent signals. We consider both static and dynamical phase diffusion and assess the performances of the channel for ideal and realistic phase receivers. Our results show that NLA employed at the stage of signal preparations is a useful resource, especially in the regime of weak signals. We also discuss the interplay between the use of NLA, and the memory effects occurring with dynamical noise, in determining the capacity of the channel.Comment: to appear in JOSA

Evolution of Superconductivity in Electron-Doped Cuprates: Magneto-Raman Spectroscopy

The electron-doped cuprates Pr_{2-x}Ce_xCuO_4 and Nd_{2-x}Ce_xCuO_4 have been studied by electronic Raman spectroscopy across the entire region of the superconducting (SC) phase diagram. The SC pairing strength is found to be consistent with a weak-coupling regime except in the under-doped region where we observe an in-gap collective mode at 4.5 k_{B}T_c while the maximum amplitude of the SC gap is ~8 k_{B}T_{c}. In the normal state, doped carriers divide into coherent quasi-particles (QPs) and carriers that remain incoherent. The coherent QPs mainly reside in the vicinity of (\pi/2, \pi/2) regions of the Brillouin zone (BZ). We find that only coherent QPs contribute to the superfluid density in the B_{2g} channel. The persistence of SC coherence peaks in the B_{2g} channel for all dopings implies that superconductivity is mainly governed by interactions between the hole-like coherent QPs in the vicinity of (\pi/2, \pi/2) regions of the BZ. We establish that superconductivity in the electron-doped cuprates occurs primarily due to pairing and condensation of hole-like carriers. We have also studied the excitations across the SC gap by Raman spectroscopy as a function of temperature (T) and magnetic field (H) for several different cerium dopings (x). Effective upper critical field lines H*_{c2}(T, x) at which the superfluid stiffness vanishes and H^{2\Delta}_{c2}(T, x) at which the SC gap amplitude is suppressed by field have been determined; H^{2\Delta}_{c2}(T, x) is larger than H*_{c2}(T, x) for all doping concentrations. The difference between the two quantities suggests the presence of phase fluctuations that increase for x< 0.15. It is found that the magnetic field suppresses the magnitude of the SC gap linearly at surprisingly small fields.Comment: 13 pages, 8 figures; submitted to Phys. Rev.

Bacteriological Quality of Fresh Vegetables and Peeled Sugar-Cane Obtained from Selected Markets in Zaria, Nigeria

Fresh vegetables and peeled sugar-cane serves as an essential component of a healthy diet, but despite their benefit they are prompt to bacterial contamination. The bacteriological quality of four types of fresh vegetables and peeled sugar-cane obtained from selected markets in Zaria, Nigeria was determined using standard microbiological method. The fresh vegetables, peeled sugar-cane, water and hand-swab samples were collected from four different locations namely; Samaru, Sabon-gari, Tudun-wada and Zaria-city. The total bacteria plate counts ranged from 3.3 x 106 cfu/g to 1.6 x 107 cfu/g with Tudu-wada having the highest bacteria load in lettuce. The coliform count of fresh vegetables and peeled sugar-cane varies from 1.3 x 104 to 8.6 x 105 cfu/g in the entire markets with Tudu-wada having the highest value in cucumber, the counts were obviously above specified Standard of 105 cfu/g and  103 cfu/g (ICMSF, 1978). Pathogenic bacteria isolated include; Citrobacter fruendii, Escherichia coli, Enterobacter spp., Klebsiella. spp., Shigella spp., Serratia spp., Cronobacter sakazaki, Staphylococcus aureus, Pseudomonas spp., and others Staphylococci spp.. This study showed that, fresh vegetables and peeled sugar-cane are contaminated with pathogenic bacteria making them unsafe for human consumption; hence fresh produce should be pre- treated thoroughly, so as to reduce the risk of food- borne outbreaks. Keywords: Pathogenic bacteria · Bacteriological quality, Microbiological method, Coliform counts and food- borne outbreaks. DOI: 10.7176/JNSR/12-8-02 Publication date: April 30th 202

THE PREVALENCE OF PTSD AND DEPRESSION AMONG GAZA CHILDREN

Purpose: The purpose of this study is to investigate the prevalence of posttraumatic distress disorder (PTSD) and depression among children in Gaza, Palestine. Methodology:&nbsp; This study assessed the psychological effects of the Israeli-Palestinian conflict on children in the Gaza Strip. 286 children aged 9-14 years old, who were exposed to a wide range of war events, were selected from the Gaza Strip to participate in this study. All participants conducted the following scales: the child PTSD Reaction Index(CPTSD-RI), Beck Depression Inventory (BDI), and the Arabic version for PTSD and depression assessment. Finding: The results show that the mean number of participants witnessing home destroyed and people killed was (88%) and home invasion (76%). Approximately 70% of the participants reported that they witnessed war violence against at least one of their family members. Further, 44 % of the children have a least one death in their family due to the Israeli invasion. Using t-tests, we found that significantly more females have both PTSD and depression than males. Approximately 32.8% of the participants met the criteria for severe depression, and 42.6 % met the criteria for PTSD. Implications: Our results suggest that it is imperative to provide intervention programs to treat PTSD and depression symptoms among children in Gaza. These programs should take into account the cultural and religious background of the participants. Originality: This investigation of the Israeli-Palestinian conflict has led to an increase in PTSD and depression symptoms among children in the Gaza Strip