Cost Effective Capture of multiple IQ streams for Phase Arrays

This paper introduces a new and affordable method of realising 10 IQ Software Defined receivers, and how to synchronise them. We first discuss the need for multiple IQ and the available techniques. We then introduce the RTL-SDR and Matlab as a very low cost prototype implementation of 10 IQ streams. This leads to the design and manufacture of a PCB to distribute a single clock to multiple RTL-SDRs. The required modifications to the RTL-SDRs to receive the distributed clock and other modifications to improve the overall performance are presented. We then describe how to attain raw IQ data and synchronise the receivers. Finally, we prove all 10 can maintain a phase lock over a frame of 7 seconds

Decreasing referrals to transient ischemic attack clinics during the COVID-19 outbreak: results from a multi-centre cross-sectional survey

Objective. The COVID-19 pandemic is having major implications for stroke care with a documented significant fall in hospital acute stroke admissions. We investigated whether COVID-19 has resulted in a decreased number of referrals to the Transient Ischemic Attack (TIA) clinics across the North West London region. Setting and Design. All the TIA clinical leads of the North West London region received an invitation by email to participate in an online survey in May 2020. The survey questionnaire aimed to assess the number of patients with suspected TIA consecutively referred to each of the TIA clinics of the North West London region between 1st March to 30th April 2020, the COVID-19 period, and between 1st March to 30th April 2019. Results. We had a response rate of 100%. During the COVID-19 period, the TIA clinics of the North West London region received 440 referrals compared to 616 referrals received between 1st March to 30th April 2019 with a fall in the number of the referrals by 28.6%. In April 2020 compared with April 2019, the number of the referrals declined by 40.1%. Conclusions. This multicentre analysis documented a significant reduction in the number of patients referred with suspected TIA to the specialised rapid access outpatient clinics in the North West London region during the COVID-19 pandemic. Future studies are needed to confirm our findings and to better characterise the incidence of cerebrovascular disease during the COVID-19 pandemic

Fast Light-Driven Motion of Polydopamine Nanomembranes

[Image: see text] The actuation of micro- and nanostructures controlled by external stimuli remains one of the exciting challenges in nanotechnology due to the wealth of fundamental questions and potential applications in energy harvesting, robotics, sensing, biomedicine, and tunable metamaterials. Photoactuation utilizes the conversion of light into motion through reversible chemical and physical processes and enables remote and spatiotemporal control of the actuation. Here, we report a fast light-to-motion conversion in few-nanometer thick bare polydopamine (PDA) membranes stimulated by visible light. Light-induced heating of PDA leads to desorption of water molecules and contraction of membranes in less than 140 μs. Switching off the light leads to a spontaneous expansion in less than 20 ms due to heat dissipation and water adsorption. Our findings demonstrate that pristine PDA membranes are multiresponsive materials that can be harnessed as robust building blocks for soft, micro-, and nanoscale actuators stimulated by light, temperature, and moisture level

Charged Particle Production in Proton-, Deuteron-, Oxygen- and Sulphur-Nucleus Collisions at 200 GeV per Nucleon

The transverse momentum and rapidity distributions of net protons and negatively charged hadrons have been measured for minimum bias proton-nucleus and deuteron-gold interactions, as well as central oxygen-gold and sulphur-nucleus collisions at 200 GeV per nucleon. The rapidity density of net protons at midrapidity in central nucleus-nucleus collisions increases both with target mass for sulphur projectiles and with the projectile mass for a gold target. The shape of the rapidity distributions of net protons forward of midrapidity for d+Au and central S+Au collisions is similar. The average rapidity loss is larger than 2 units of rapidity for reactions with the gold target. The transverse momentum spectra of net protons for all reactions can be described by a thermal distribution with `temperatures' between 145 +- 11 MeV (p+S interactions) and 244 +- 43 MeV (central S+Au collisions). The multiplicity of negatively charged hadrons increases with the mass of the colliding system. The shape of the transverse momentum spectra of negatively charged hadrons changes from minimum bias p+p and p+S interactions to p+Au and central nucleus-nucleus collisions. The mean transverse momentum is almost constant in the vicinity of midrapidity and shows little variation with the target and projectile masses. The average number of produced negatively charged hadrons per participant baryon increases slightly from p+p, p+A to central S+S,Ag collisions.Comment: 47 pages, submitted to Z. Phys.

NectarCAM : a camera for the medium size telescopes of the Cherenkov Telescope Array

NectarCAM is a camera proposed for the medium-sized telescopes of the Cherenkov Telescope Array (CTA) covering the central energy range of ~100 GeV to ~30 TeV. It has a modular design and is based on the NECTAr chip, at the heart of which is a GHz sampling Switched Capacitor Array and a 12-bit Analog to Digital converter. The camera will be equipped with 265 7-photomultiplier modules, covering a field of view of 8 degrees. Each module includes the photomultiplier bases, high voltage supply, pre-amplifier, trigger, readout and Ethernet transceiver. The recorded events last between a few nanoseconds and tens of nanoseconds. The camera trigger will be flexible so as to minimize the read-out dead-time of the NECTAr chips. NectarCAM is designed to sustain a data rate of more than 4 kHz with less than 5\% dead time. The camera concept, the design and tests of the various subcomponents and results of thermal and electrical prototypes are presented. The design includes the mechanical structure, cooling of the electronics, read-out, clock distribution, slow control, data-acquisition, triggering, monitoring and services.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

The camera of the fifth H.E.S.S. telescope. Part I: System description

In July 2012, as the four ground-based gamma-ray telescopes of the H.E.S.S. (High Energy Stereoscopic System) array reached their tenth year of operation in Khomas Highlands, Namibia, a fifth telescope took its first data as part of the system. This new Cherenkov detector, comprising a 614.5 m^2 reflector with a highly pixelized camera in its focal plane, improves the sensitivity of the current array by a factor two and extends its energy domain down to a few tens of GeV. The present part I of the paper gives a detailed description of the fifth H.E.S.S. telescope's camera, presenting the details of both the hardware and the software, emphasizing the main improvements as compared to previous H.E.S.S. camera technology.Comment: 16 pages, 13 figures, accepted for publication in NIM