Influence of modulation frequency in rubidium cell frequency standards

The error signal which is used to control the frequency of the quartz crystal oscillator of a passive rubidium cell frequency standard is considered. The value of the slope of this signal, for an interrogation frequency close to the atomic transition frequency is calculated and measured for various phase (or frequency) modulation waveforms, and for several values of the modulation frequency. A theoretical analysis is made using a model which applies to a system in which the optical pumping rate, the relaxation rates and the RF field are homogeneous. Results are given for sine-wave phase modulation, square-wave frequency modulation and square-wave phase modulation. The influence of the modulation frequency on the slope of the error signal is specified. It is shown that the modulation frequency can be chosen as large as twice the non-saturated full-width at half-maximum without a drastic loss of the sensitivity to an offset of the interrogation frequency from center line, provided that the power saturation factor and the amplitude of modulation are properly adjusted

A Literature Review on Substance Related Grief and Expressive Art Therapy Support Groups

In the year of 2017, 18.7 million Americans aged 18 years or older were reported to have a substance use disorder and the pervasiveness of substance related deaths escalated (McCance- Katz, 2017). Researchers have examined how grief experienced by substance users and their loved ones is often disenfranchised by social stigmatization, loss of support, and feelings of regret, blame, humiliation, and shame. According to Valentine, Bauld, and Walter, (2016) “bereavement following a drug or alcohol related death has been largely neglected in research and service provision, despite its global prevalence and potentially devastating consequences for those concerned,” (p. 283). Studies demonstrate a need for further research on death and loss within contemporary societies, while highlighting the demand for psychological support and resources for the bereaved impacted by substance abuse. The purpose of this literature review aimed to contribute a better understanding of this population and connect existing research to piece together the best practices to better serve them. This critical literature review consists of three sections examining the individualized grief experiences of this population within western cultures, the consequences of addiction, and drug use stigmatization. Lastly, the literature on grief support groups, substance abuse resources, and expressive art therapy practices will be summarized. Results uncovered certain themes and areas of complex grief within this population to consider for clinical applications in expressive art therapy support groups. For example, expressing secret and negative feelings about addictions in a safe, non-threatening way within a therapeutic group setting can bring victims out of the isolating effects of stigmatized loss (Mayton and Wester, 2018). Furthermore, this thesis discovered gaps in the literature for interventions designed to provide assistance for healing after drug-related losses

Sterile neutrino dark matter: A tale of weak interactions in the strong coupling epoch

We perform a detailed study of the weak interactions of standard model neutrinos with the primordial plasma and their effect on the resonant production of sterile neutrino dark matter. Motivated by issues in cosmological structure formation on small scales, and reported X-ray signals that could be due to sterile neutrino decay, we consider $7$ keV-scale sterile neutrinos. Oscillation-driven production of such sterile neutrinos occurs at temperatures $T \gtrsim 100$ MeV, where we study two significant effects of weakly charged species in the primordial plasma: (1) the redistribution of an input lepton asymmetry; (2) the opacity for active neutrinos. We calculate the redistribution analytically above and below the quark-hadron transition, and match with lattice QCD calculations through the transition. We estimate opacities due to tree level processes involving leptons and quarks above the quark-hadron transition, and the most important mesons below the transition. We report final sterile neutrino dark matter phase space densities that are significantly influenced by these effects, and yet relatively robust to remaining uncertainties in the nature of the quark-hadron transition. We also provide transfer functions for cosmological density fluctuations with cutoffs at $k \simeq 10 \ h \ {\rm Mpc}^{-1}$, that are relevant to galactic structure formation.Comment: 28 pages, 11 figures, code repository at https://github.com/ntveem/sterile-d

Two types of nematicity in the phase diagram of the cuprate superconductor YBa2_2Cu3_3Oy_y

Nematicity has emerged as a key feature of cuprate superconductors, but its link to other fundamental properties such as superconductivity, charge order and the pseudogap remains unclear. Here we use measurements of transport anisotropy in YBa$_2$Cu$_3$O$_y$ to distinguish two types of nematicity. The first is associated with short-range charge-density-wave modulations in a doping region near $p = 0.12$. It is detected in the Nernst coefficient, but not in the resistivity. The second type prevails at lower doping, where there are spin modulations but no charge modulations. In this case, the onset of in-plane anisotropy - detected in both the Nernst coefficient and the resistivity - follows a line in the temperature-doping phase diagram that tracks the pseudogap energy. We discuss two possible scenarios for the latter nematicity.Comment: 8 pages and 7 figures. Main text and supplementary material now combined into single articl

Competency Corner, Part Three: Practice-based Weightings of the CBPS

The first two articles in this series outlined the task, research, terminology and processes the Competence Committee used to develop the Competency-based Performance Standards (CBPS). These standards were designed as a framework for revision of the Canadian Standard Assessment in Optometry (CSAO) to directly link the exam and practice requirements of Canadian Optometrists. This linkage required determination of the relative weight to be assigned to each of the various competencies. Working groups of practising optometrists rated the frequency and criticality of performance of each of the competencies using a standardized rating system. Results indicated that the majority of a revised CSAO would focus on providing comprehensive eye and vision care (78%), followed by management (11%) and collaboration (10%). The ratings also allowed calculation of the appropriate weighting of the underlying general attributes. The heaviest weighting was assigned to candidates’ professional optometric knowledge and the ability to apply this knowledge (41%), followed by communication (27%), planning (13%), ethics (11%) and self-directed learning (8%). The last article in this series will describe work to evaluate the competence-based weightings of the current CSAO and to describe plans for future versions of the CSAO

Sexual abuse of intellectually disabled youth : a review

Intellectual disability (ID) is a condition characterized by significant limitations in intellectual functioning and adaptive behavior, which affects various everyday social and practical skills. This disability manifests itself before the age of 18 (American Association on Intellectual and Developmental Disabilities [AAIDD], 2010). While the global prevalence of ID is only 1% (Maulik, Mascarenhas, Mathers, Dua & Saxena, 2011), research shows that the risk of being sexually abused is 2 to 6 times greater among intellectually disabled youth than among typically developing youth (Dion, Bouchard, Gaudreault & Mercier, 2012). It is also argued that the prevalence of sexual abuse may be underestimated among intellectually disabled youth, as disclosure may be more difficult for them because of their limited vocabulary and communicative abilities (Murphy, 2007). Despite this higher risk, professionals who work with this population have little information on the issue. Myths and prejudices which devalue intellectually disabled people in our society, such as the notions that they are asexual or that they do not suffer, may increase their vulnerability to sexual abuse (Mansell & Sobsey, 2001). Expanding our knowledge in the field of ID and sexual abuse may help dispel these myths and break down these prejudices. This article presents a literature review that aims to 1) provide an overview of sexual abuse of intellectually disabled youth, and 2) discuss the implications for prevention and intervention for these vulnerable youth

Hsp70 in mitochondrial biogenesis

The family of hsp70 (70 kilodalton heat shock protein) molecular chaperones plays an essential and diverse role in cellular physiology, Hsp70 proteins appear to elicit their effects by interacting with polypeptides that present domains which exhibit non-native conformations at distinct stages during their life in the cell. In this paper we review work pertaining to the functions of hsp70 proteins in chaperoning mitochondrial protein biogenesis. Hsp70 proteins function in protein synthesis, protein translocation across mitochondrial membranes, protein folding and finally the delivery of misfolded proteins to proteolytic enzymes in the mitochondrial matrix