Collaborative Randomized Beamforming for Phased Array Radio Interferometers

The Square Kilometre Array (SKA) will form the largest radio telescope ever built and such a huge instrument in the desert poses enormous engineering and logistic challenges. Algorithmic and architectural breakthroughs are needed. Data is collected and processed in groups of antennas before transport for central processing. This processing includes beamforming, primarily so as to reduce the amount of data sent. The principal existing technique points to a region of interest independently of the sky model and how the other stations beamform. We propose a new collaborative beamforming algorithm in order to maximize information captured at the stations (thus reducing the amount of data transported). The method increases the diversity in measurements through randomized beam- forming. We demonstrate through numerical simulation the effectiveness of the method. In particular, we show that randomized beamforming can achieve the same image quality while producing 40% less data when compared to the prevailing method matched beamforming.Comment: 9 pages, 8 figure

Risk factors related to COVID-19 survival and mortality: a cross-sectional-descriptive study in regional COVID-19 registry in Fasa, Iran

INTRODUCTION: The COVID-19 pandemic, as the most important health challenge in the world today, has made numerous irretrievable damages to the social, economic, and health dimensions of societies, especially in developing countries. An essential measure that can be taken to prevent and control the disease is to identify risk factors related to its prognosis and mortality rate. Therefore, this study aimed at investigating COVID-19 survival and mortality risk factors and their relationship with the demographic characteristics of the subjects diagnosed with the disease. MATERIAL AND METHODS: The present study is cross-sectional and descriptive. The samples consist of 1395 patients diagnosed with COVID-19 admitted to medical centers affiliated with Fasa University of Medical Sciences. The subjects were selected by census sampling. Data were collected using demographic information forms, paraclinical and radiological tests, and clinical examinations. Data were analyzed using SPSS version 18 via descriptive tests, paired t-tests, one-way ANOVA, and post hoc tests. RESULTS: According to the data, the participants’ average age was 57.72 ± 4.63 years, and most of them (56.41%) were male. The mortality rate among the participants was estimated to be 13.19%. The results of the study showed a significant relationship between the survival status of patients with COVID-19 and underlying chronic diseases such as diabetes and cardiovascular and renal diseases (p < 0.05). CONCLUSIONS: Identifying high-risk groups is an important measure that health professionals should consider in controlling epidemics. The findings of this study showed that the presence of underlying chronic diseases such as diabetes and cardiac and renal conditions, which are associated with immune system defects, are among the most important factors related to the COVID-19 mortality

Constraining the epoch of reionization with the variance statistic: simulations of the LOFAR case

Several experiments are underway to detect the cosmic redshifted 21-cm signal from neutral hydrogen from the Epoch of Reionization (EoR). Due to their very low signal-to-noise ratio, these observations aim for a statistical detection of the signal by measuring its power spectrum. We investigate the extraction of the variance of the signal as a first step towards detecting and constraining the global history of the EoR. Signal variance is the integral of the signal's power spectrum, and it is expected to be measured with a high significance. We demonstrate this through results from a simulation and parameter estimation pipeline developed for the Low Frequency Array (LOFAR)-EoR experiment. We show that LOFAR should be able to detect the EoR in 600 hours of integration using the variance statistic. Additionally, the redshift ($z_r$) and duration ($\Delta z$) of reionization can be constrained assuming a parametrization. We use an EoR simulation of $z_r = 7.68$ and $\Delta z = 0.43$ to test the pipeline. We are able to detect the simulated signal with a significance of 4 standard deviations and extract the EoR parameters as $z_r = 7.72^{+0.37}_{-0.18}$ and $\Delta z = 0.53^{+0.12}_{-0.23}$ in 600 hours, assuming that systematic errors can be adequately controlled. We further show that the significance of detection and constraints on EoR parameters can be improved by measuring the cross-variance of the signal by cross-correlating consecutive redshift bins.Comment: 13 pages, 14 figures, Accepted for publication in MNRA

Efficient and accurate calibration for radio interferometers

Optische telescopen hebben detectoren die gevoelig zijn voor individuele fotonen die het detectoroppervlak raken. Hiermee kan de helderheid van een lichtbron aan de hemel gemeten worden. Optische telescopen zijn gevoelig voor fotonen met een golflengte tussen de 400 nanometer (paars) en 700 nanometer (rood), maar ook op andere golflengtes zijn fascinerende dingen aan de hemel zichtbaar. Om ook straling op andere golflengtes waar te nemen, waaronder rontgenstraling, gammastraling, ultraviolet, infrarood en radiogolven, gebruiken astronomen verschillende andere typen telescopen. Van al deze typen straling beslaat het radiogebied het grootste golflengtebereik, van ongeveer 1 millimeter tot honderden meters (zie figuur 7.1). Radiogolflengtes worden waargenomen met radiotelescopen, waarmee astronomische kennis kan worden vergaard die ontoegankelijk is op elk ander golflengtegebied. Een voorbeeld hiervan is de vorming van de eerste objecten in het vroege universumen hun invloed op het intergalactischmedium, iets wat zelfsmet demeest geavanceerde optische telescopen niet kan worden waargenomen. Zodoende spelen radiotelescopen een cruciale rol in fundamenteel astronomisch onderzoek en hebben bijgedragen aan de ontdekking van quasars, pulsars, zwarte gate en vele andere astronomische objecten. De eerst radio antenne ontvanger werd in 1933 geconstrueerd door de Amerikaanse elektrotechnisch ingenieur Karl Jansky, met als doel het opsporen van bronnen voor telefooninterferentie. Hij ontdekte een radiosignaal met onbekende bron dat zichzelf dagelijks herhaalde, waarmee hij uiteindelijk het centrum van de Melkweg kon traceren. Voortbouwend op zijn werk werden vele schotelvormige radiotelescopen ontworpen, de eerste daarvan was een schotel van 9 meter in 1935 gemaakt door Grote Reber, een andere Amerikaanse elektrotechnisch ingenieur. Toenemende eisen aan de resolutie maakte schotelvormige antennes onpraktisch, waarmee de weg werd vrijgemaakt voor radio-interferometrische telescopen met meerdere ontvangers. Elk van deze ontvangers was nog steeds een schotelvormige radiotelescoop, maar door een array van zulke telescopen te linken ontstaat een virtuele telescoop die veel groter is dan elk van de aparte schotels. Het gebruik van een array van antennes heeft als extra voordeel dat door slim combineren van de signalen van de aparte antennes de hoeveelheid ruis drastisch kan worden gereduceerd. De eerste radio-interferometer werd in 1946 geconstrueerd door Marin Ryle en had slechts twee stuurbare dipoolantenneswiens onderlinge afstand kon vari˘A≪ren tussen de 17 en 240meter. Sindsdien zijn er vele radio-interferometers gebouwd. Prominente voorbeelden zijn de Very Long Baseline Array (VLBA, zie figuur 7.2), een van ’s werelds grootste radio-interferometers met 25 meter grote schotelvormige ontvangers in voornamelijk Noord Amerika en de LOw Frequency ARray (LOFAR, zie figuur 7.3), een array van ongeveer 1000 kilometer met bijna 20000 dipool antenne-ontvangers verspreid over voornamelijk Nederland.

Safety and Therapeutic Effects of Repetitive Transcranial Magnetic Stimulation and Behavior Therapy in a Pregnant Woman: Case Report

In this study, the authors reported a case of woman with severe compulsion who became pregnant during the Repetitive transcranial magnetic stimulation. We carried out Repetitive transcranial magnetic stimulation and behavior therapy simultaneously after repeated medications' refraction. The patient received 20 sessions 1 Hz Repetitive transcranial magnetic stimulation in right dorsolateral prefrontal cortex and behavior therapy at the same time in repetitive transcranial magnetic stimulation room. We asked the patient to exposure her fear and without permission of doing usual behavior (washing), she was receiving repetitive transcranial magnetic stimulation. Repetitive transcranial magnetic stimulation and Behavior Therapy could reduce her symptoms significantly. Although her baby was healthy physically but some areas of Age and Stage Questionnaire were below than the average. Repetitive transcranial magnetic stimulation with an additional psychotherapy as behavior therapy could accelerate the improvement of Obsessive compulsive disorder's symptoms. Furthermore, using Repetitive transcranial magnetic stimulation during the first of trimester probably couldn’t be safe for pregnant woman

Effect of Arginine, Protamine, and Aqueous Extracts of Green Tea and Aloe Vera Against Enterococcus faecalis

Background and Aim: Because of complexity in root canals, irrigating solutions are needed in addition to mechanical instrumentation for thorough cleansing of the root canal system. This in-vitro study was designed to determine the inhibitory effect of arginine, protamine, and aqueous extracts of green tea and aloe vera against Enterococcus faecalis (E. faecalis), which causes endodontic failure. Materials and Methods: In this experimental study, aqueous extracts of green tea and aloe vera and protamine at a concentration of 400 mg/ml and arginine at a concentra-tion of 160 mg/ml were used. E. faecalis was cultured on Mueller-Hinton broth, and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the test materials against these microorganisms were determined using serial dilutions and according to the microdilution test. The positive control was 2.5% sodium hypochlorite (NaOCl). Results: Aqueous extract of aloe vera has high antibacterial activity against E. faecalis (MIC=12.5 mg/ml and MBC=100 mg/ml), and protamine had the least effect (MIC=400 mg/ml and MBC>400 mg/ml) compared to other test materials. NaOCl, with MIC and MBC of 0.25 mg/ml against E. faecalis, showed higher antibacterial activity compared to other test materials. Conclusion: Among the tested materials, except for NaOCl as a positive control, aqueous extract of aloe vera showed better antibacterial properties against E. faecalis

Imaging in radio interferometry by iterative subset scanning using a modified AMP algorithm

Imaging techniques in radio interferometry often face a significant challenge posed by the large number of antenna signals received, from which the image information needs to be extracted. Beamforming is envisaged to reduce the rate required for transporting data from groups of antennas to a central site for further processing. We propose a novel method for image reconstruction based on the iterative scanning of a region of interest, combined with randomized beamforming. A modified approximate message-passing algorithm is adopted to extract relevant image information from beamformed signals received at the antenna stations. The method is illustrated by simulations, with reference to the LOFAR radio interferometer, and compared with the CLEAN algorithm

Iterative image subset scanning for image reconstruction from sensor signals

Image reconstruction techniques from signals received by sensors find application in several fields, including radio interferometry for astronomical investigations and magnetic resonance imaging for medical applications. This paper presents a novel method for image reconstruction based on the iterative scanning of a region of interest. A modified approximate message passing (AMP) algorithm is adopted to extract relevant image information with low computational complexity from signals received by sensors. The method is illustrated by simulations, with reference to the LOFAR radio interferometer, and compared in the case of radio astronomy with the CLEAN algorithm

Effect of Triple Antibiotic Paste on Bond Strength of Composite to Dentin: An In Vitro Study

Background and Aim: Considering the increasing use of antibiotics in root canal therapy and the possible effects of intracanal medicaments on the bond strength of composite restorations, the aim of this study was to evaluate the effect of triple antibiotic paste (TAP) on shear bond strength of three types of composite resins to dentin. Materials and Methods: In this in-vitro, experimental study, the enamel of 60 extracted premolars was ground parallel to the longitudinal axis of the teeth in order to produce flat dentin surfaces (5 mm2 minimum surface area). The samples were divided into six groups. In the control group, dentin surfaces were stored in saline solution and in the experimental groups dentin surfaces were exposed to TAP for 10 days. After washing and drying, Single Bond was applied for dentin bond to Z100 and Z350 composites. Adhesive resin was used for bond to P90 composite. Composites were applied on the dentin surfaces in six groups and cured in four directions. The shear bond strength was measured by Instron machine. The data were analyzed by t-test, one-way ANOVA and Tukey’s test. Results: The highest mean shear bond strength was found in Z350 composite group following the use of TAP (38.75 MPa) and the lowest mean strength was found in Z100 composite group following the use of TAP (14.64 MPa). The mean shear bond strength of P90 and Z100 composites (in contrast to Z350 composite) was higher in the saline compared to the TAP groups (p=0.1). The differences between saline and antibiotic groups were not significant (p=0.959) but the difference in this regard among the three types of composites was significant. Conclusion: The results of this study showed that use of TAP has no effect on the shear bond strength of composite to dentin but the type of composite significantly affects the shear bond strength