An Experiment and Detection Scheme for Cavity-based Cold Dark Matter Searches

A resonance detection scheme and some useful ideas for cavity-based searches of light cold dark matter particles (such as axions) are presented, as an effort to aid in the on-going endeavors in this direction as well as for future experiments, especially in possibly developing a table-top experiment. The scheme is based on our idea of a resonant detector, incorporating an integrated Tunnel Diode (TD) and a GaAs HEMT/HFET (High Electron Mobility Transistor/Heterogenous FET) transistor amplifier, weakly coupled to a cavity in a strong transverse magnetic field. The TD-amplifier combination is suggested as a sensitive and simple technique to facilitate resonance detection within the cavity while maintaining excellent noise performance, whereas our proposed Halbach magnet array could serve as a low-noise and permanent solution replacing the conventional electromagnets scheme. We present some preliminary test results which demonstrate resonance detection from simulated test signals in a small optimal axion mass range with superior Signal-to-Noise Ratios (SNR). Our suggested design also contains an overview of a simpler on-resonance dc signal read-out scheme replacing the complicated heterodyne readout. We believe that all these factors and our propositions could possibly improve or at least simplify the resonance detection and read-out in cavity-based DM particle detection searches (and other spectroscopy applications) and reduce the complications (and associated costs), in addition to reducing the electromagnetic interference and background.Comment: 22 pages, 7 figure

Honoring Don Whitley, pioneer of innovative scientific instruments for Anaerobic Microbiology (1929-2019)

Don Whitley Scientific Limited announced the sad news of the death of its founder and chairman, Don Whitley on February 28, 2019. We mourn the loss of this great scientific entrepreneur who was born in London in June 1929. With his family’s relocation to Leeds in 1940, Don attended Leeds’s prestigious Morley Grammar School where he envisioned a career as a medical doctor. Family’s opposition led him to medical technology, working for a decade at Leeds Maternity Hospital and Killingbeck Hospital before moving to industry

A functional description of the Buffered Telemetry Demodulator (BTD)

This article gives a functional description of the buffered telemetry demodulator (BTD), which operates on recorded digital samples to extract the symbols from the received signal. The key advantages of the BTD are as follows: (1) its ability to reprocess the signal to reduce acquisition time; (2) its ability to use future information about the signal and to perform smoothing on past samples; and (3) its minimum transmission bandwidth requirement as each sub carrier harmonic is processed individually. The first application of the BTD would be the Galileo S-band contingency mission, where the signal is so weak that reprocessing to reduce the acquisition time is crucial. Moreover, in the event of employing antenna arraying with full spectrum combining, only the sub carrier harmonics need to be transmitted between sites, resulting in significant reduction in data rate transmission requirements. Software implementation of the BTD is described for various general-purpose computers

Deformed Complex Hermite Polynomials

We study a class of bivariate deformed Hermite polynomials and some of their properties using classical analytic techniques and the Wigner map. We also prove the positivity of certain determinants formed by the deformed polynomials. Along the way we also work out some additional properties of the (undeformed) complex Hermite polynomials and their relationships to the standard Hermite polynomials (of a single real variable).Comment: 12 page

STD Services Delivery Arrangements in Georgia County Health Departments

Background: Uniformity, standardization, and evidence-based public health practice are needed to improve the efficiency and quality of services in local health departments (LHDs). Among the highest priority and most common public health services delivered by LHDs are services related to sexually transmitted diseases (STDs) and sexually transmitted infections (STIs).Objective: The purpose of this study was to examine potential variations in the delivery of sexually transmitted disease (STD) services among county health departments (CHD) in Georgia, to determine if potential variations were due to varied administrative practices, and to understand delivery arrangements so that future cost studies can be supported.Methods: Web-based surveys were collected from 134 county health departments in Georgia in 2015.Results: Screening for gonorrhea, chlamydia and syphilis occurred in all the surveyed CHDs. Sixty-eight percent of the CHDs had one or more staff who performed investigations for persons already screened positive for STDs. Partner notification services provided by the CHD staff occurred in only 35 percent of the surveyed CHDs.Conclusions: Variances regarding diagnostic methodologies, work time expenditures, and staff responsibilities likely had an influence on the delivery of STD services across Georgia's CHDs. There are opportunities for uniformity and standardization of administrative practices

MATLAB Simulink model of a photovoltaic cell

Материалы XVIII Междунар. науч.-техн. конф. студентов, аспирантов и молодых ученых, Гомель, 26–27 апр. 2018 г

Multiband monopole antenna for mobile applications

— In this paper, a multiband monopole antenna has been proposed for mobile applications. The monopole antenna has simple structure with a physical size of 15 cm × 7 cm. The antenna consists of monopole shape loaded by a set of folded arms with a varying length which lead to a better impedance matching result and multiband performance. The simulated results show that the proposed antenna provide multiband frequency operation of 0.8 GHz, 1.8 GHz 2.1 GHz, 2.6 GHz and 3.5 GHz which covers the range from 0 to 4 GHz. The antenna is designed to operate at sub-6 GHz which proposed as lower frequency band to deliver 5G in early stage. The designed antenna has been fabricated and measured to validate the simulated results. RF Coaxial U.FL Connector was used as the port connector. The measurement results agrees well with the simulated ones for all frequency bands

Energy relaxation of an excited electron gas in quantum wires: many-body electron LO-phonon coupling

We theoretically study energy relaxation via LO-phonon emission in an excited one-dimensional electron gas confined in a GaAs quantum wire structure. We find that the inclusion of phonon renormalization effects in the theory extends the LO-phonon dominated loss regime down to substantially lower temperatures. We show that a simple plasmon-pole approximation works well for this problem, and discuss implications of our results for low temperature electron heating experiments in quantum wires.Comment: 10 pages, RevTex, 4 figures included. Also available at http://www-cmg.physics.umd.edu/~lzheng

An alternative explanation for the density depletions observed by Freja and Viking satellites

In this paper, we have studied the linear and nonlinear propagation of ion acoustic waves in the presence of electrons that follow the generalized (r,q) distribution. It has been shown that for positive values of r, which correspond to a flat-topped electron velocity distribution, the nonlinear ion acoustic waves admit rarefactive solitary structures or density depletions. It has been shown that the generalized (r,q) distribution function provides another way to explicate the density depletions observed by Freja and Viking satellites previously explained by proposing Cairns distribution function.In this paper, we have studied the linear and nonlinear propagation of ion acoustic waves in the presence of electrons that follow the generalized (r,q) distribution. It has been shown that for positive values of r, which correspond to a flat-topped electron velocity distribution, the nonlinear ion acoustic waves admit rarefactive solitary structures or density depletions. It has been shown that the generalized (r,q) distribution function provides another way to explicate the density depletions observed by Freja and Viking satellites previously explained by proposing Cairns distribution function