Step-on versus step-off signals in time-domain controlled source electromagnetic methods using a grounded electric dipole

The time‐domain controlled source electromagnetic method is a geophysical prospecting tool applied to image the subsurface resistivity distribution on land and in the marine environment. In its most general setup, a square‐wave current is fed into a grounded horizontal electric dipole, and several electric and magnetic field receivers at defined offsets to the imposed current measure the electromagnetic response of the Earth. In the marine environment, the application often uses only inline electric field receivers that, for a 50% duty‐cycle current waveform, include both step‐on and step‐off signals. Here, forward and inverse 1D modelling is used to demonstrate limited sensitivity towards shallow resistive layers in the step‐off electric field when transmitter and receivers are surrounded by conductive seawater. This observation is explained by a masking effect of the direct current signal that flows through the seawater and primarily affects step‐off data. During a step‐off measurement, this direct current is orders of magnitude larger than the inductive response at early and intermediate times, limiting the step‐off sensitivity towards shallow resistive layers in the seafloor. Step‐on data measure the resistive layer at times preceding the arrival of the direct current signal leading to higher sensitivity compared to step‐off data. Such dichotomous behaviour between step‐on and step‐off data is less obvious in onshore experiments due to the lack of a strong overlying conductive zone and corresponding masking effect from direct current flow. Supported by synthetic 1D inversion studies, we conclude that time‐domain controlled source electromagnetic measurements on land should apply both step‐on and step‐off data in a combined inversion approach to maximise signal‐to‐noise ratios and utilise the sensitivity characteristics of each signal. In an isotropic marine environment, step‐off electric fields have inferior sensitivity towards shallow resistive layers compared to step‐on data, resulting in an increase of non‐uniqueness when interpreting step‐off data in a single or combined inversion

The reliability of perinatal and neonatal mortality rates: Differential under-reporting in linked professional registers vs. Dutch civil registers

Official Dutch perinatal mortality rates are based on birth and death certificates. These civil registration data are not detailed enough for international comparisons or extensive epidemiological research. In this study, we linked and extrapolated three national incomplete, professional registers from midwives, obstetricians and paediatricians, containing detailed perinatal information. This linkage and extrapolation resulted in one detailed professional database which is representative of all Dutch births and from which gestational age-specific perinatal mortality rates could be calculated. The reliability of these calculated mortality rates was established by comparing them with the rates derived from the national civil registers. The professional database reported more perinatal deaths and fewer late neonatal deaths than the civil registers. The underreporting in the civil registers amounted to 1.2 fewer perinatal deaths per 1000 births and was most apparent in immature newborns. We concluded that under-reporting of perinatal and neonatal deaths depends on the data source used. Mortality rates for the purpose of national and international comparison should, therefore, be defined with caution. This study also demonstrated that combining different incomplete professional registers can result in a more reliable database containing detailed perinatal information. Such databases can be used as the basis for extensive perinatal epidemiological research

Models of quintessence coupled to the electromagnetic field and the cosmological evolution of alpha

We study the change of the effective fine structure constant in the cosmological models of a scalar field with a non-vanishing coupling to the electromagnetic field. Combining cosmological data and terrestrial observations we place empirical constraints on the size of the possible coupling and explore a large class of models that exhibit tracking behavior. The change of the fine structure constant implied by the quasar absorption spectra together with the requirement of tracking behavior impose a lower bound of the size of this coupling. Furthermore, the transition to the quintessence regime implies a narrow window for this coupling around $10^{-5}$ in units of the inverse Planck mass. We also propose a non-minimal coupling between electromagnetism and quintessence which has the effect of leading only to changes of alpha determined from atomic physics phenomena, but leaving no observable consequences through nuclear physics effects. In doing so we are able to reconcile the claimed cosmological evidence for a changing fine structure constant with the tight constraints emerging from the Oklo natural nuclear reactor.Comment: 13 pages, 10 figures, RevTex, new references adde

The detection of a strong episignature for Chung–Jansen syndrome, partially overlapping with Börjeson–Forssman–Lehmann and White–Kernohan syndromes

Chung-Jansen syndrome is a neurodevelopmental disorder characterized by intellectual disability, behavioral problems, obesity and dysmorphic features. It is caused by pathogenic variants in the PHIP gene that encodes for the Pleckstrin homology domain-interacting protein, which is part of an epigenetic modifier protein complex. Therefore, we hypothesized that PHIP haploinsufficiency may impact genome-wide DNA methylation (DNAm). We assessed the DNAm profiles of affected individuals with pathogenic and likely pathogenic PHIP variants with Infinium Methylation EPIC arrays and report a specific and sensitive DNAm episignature biomarker for Chung–Jansen syndrome. In addition, we observed similarities between the methylation profile of Chung–Jansen syndrome and that of functionally related and clinically partially overlapping genetic disorders, White–Kernohan syndrome (caused by variants in DDB1 gene) and Börjeson–Forssman–Lehmann syndrome (caused by variants in PHF6 gene). Based on these observations we also proceeded to develop a common episignature biomarker for these disorders. These newly defined episignatures can be used as part of a multiclass episignature classifier for screening of affected individuals with rare disorders and interpretation of genetic variants of unknown clinical significance, and provide further insights into the common molecular pathophysiology of the clinically-related Chung–Jansen, Börjeson–Forssman–Lehmann and White–Kernohan syndromes.</p

Controls of knowledge production, sharing and use in bureaucratized Professional Service Firms

One of the main obstacles to the current bureaucratization trend in large professional service firms (PSFs) is the organic nature of professional knowledge production, sharing and use. Centralized knowledge management (KM) systems aimed at codifying ‘best practice’ solutions to recurrent client questions for large-scale reuse are a common strategy increasingly employed to overcome this obstacle. Using a socio-ethnographic case study of a business law firm in Paris, this research examines whether the use of centralized KM systems in bureaucratized PSFs contributes to a shift in power from professionals to managers. More specifically, are administrative controls over knowledge resources increasing, or do professionals retain power (i.e. some level of social and self-control) over knowledge production, sharing and use? The results of this study indicate that, far from losing ground, professionals’ social and self-controls have been reinvented and reformed in a bureaucratized context

Updated Nucleosynthesis Constraints on Unstable Relic Particles

We revisit the upper limits on the abundance of unstable massive relic particles provided by the success of Big-Bang Nucleosynthesis calculations. We use the cosmic microwave background data to constrain the baryon-to-photon ratio, and incorporate an extensively updated compilation of cross sections into a new calculation of the network of reactions induced by electromagnetic showers that create and destroy the light elements deuterium, he3, he4, li6 and li7. We derive analytic approximations that complement and check the full numerical calculations. Considerations of the abundances of he4 and li6 exclude exceptional regions of parameter space that would otherwise have been permitted by deuterium alone. We illustrate our results by applying them to massive gravitinos. If they weigh ~100 GeV, their primordial abundance should have been below about 10^{-13} of the total entropy. This would imply an upper limit on the reheating temperature of a few times 10^7 GeV, which could be a potential difficulty for some models of inflation. We discuss possible ways of evading this problem.Comment: 40 pages LaTeX, 18 eps figure

A case-only study to identify genetic modifiers of breast cancer risk for BRCA1/BRCA2 mutation carriers

Breast cancer (BC) risk for BRCA1 and BRCA2 mutation carriers varies by genetic and familial factors. About 50 common variants have been shown to modify BC risk for mutation carriers. All but three, were identified in general population studies. Other mutation carrier-specific susceptibility variants may exist but studies of mutation carriers have so far been underpowered. We conduct a novel case-only genome-wide association study comparing genotype frequencies between 60,212 general population BC cases and 13,007 cases with BRCA1 or BRCA2 mutations. We identify robust novel associations for 2 variants with BC for BRCA1 and 3 for BRCA2 mutation carriers, P < 10−8, at 5 loci, which are not associated with risk in the general population. They include rs60882887 at 11p11.2 where MADD, SP11 and EIF1, genes previously implicated in BC biology, are predicted as potential targets. These findings will contribute towards customising BC polygenic risk scores for BRCA1 and BRCA2 mutation carriers

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Correlation of Quantitative Measurements with Diabetic Disease Severity Utilizing Multiple En-Face OCTA Image Averaging

Purpose: To evaluate the effect of averaging en-face optical coherence tomography angiography (OCTA) images on quantitative measurements of the retinal microvasculature and their correlation to diabetic retinopathy (DR) disease severity. Design: Cross-sectional cohort study PARTICIPANTS: 105 eyes (65 patients) with 28 eyes from 19 healthy, aged-matched controls, 14 eyes from 9 diabetics without DR and 63 eyes from 37 diabetics with varying levels of DR. Methods: Spectral-domain OCTA images with uniform illumination, good foveal centration, and no macular edema or significant motion artifact were acquired 5 times with the 3x3 mm scan pattern on the CIRRUSTM 5000 HD-OCT with AngioPlex (Carl Zeiss Meditec, Dublin, CA) software. En-face images of the superficial retinal layer (SRL) and deep retinal layer (DRL) were registered and averaged. Included eyes had a signal strength 657. Vessel length density (VLD), perfusion density (PD) and foveal avascular zone (FAZ) parameters were measured on averaged versus single OCTA images. Pearson correlation coefficient compared the two groups. Univariate and multivariate linear regression correlated quantitative metrics to DR severity and best corrected visual acuity (BCVA). Results: 84 eyes (55 patients) met the inclusion criteria. Almost uniformly, lower VLD and PD parameters were significantly associated with worse DR severity and BCVA. Multivariable linear regression for DR severity resulted in an R2 value of 0.82 and 0.77 for single and averaged groups, respectively. No variables remained significantly associated with DR severity in multivariate analysis with single images but in averaged images, increased superior SRL PD significantly predicted worse DR severity (coefficient 52.7, p=0.026). Multivariate linear regression for BCVA had an R2 value of 0.42 and 0.47 for single and averaged groups, respectively. FAZ size was not associated with DR severity when single OCTA images (p=0.98) were considered, but was highly associated when using averaged images (coefficient 6.18, p&lt;0.001). FAZ size was predictive for logMAR BCVA with averaged images (0.21, p=0.004), but not with single images (p=0.31). Conclusions: Averaging of en-face OCTA images improves the visualization of capillaries, particularly increasing the clarity of the FAZ borders, and therefore improves the correlation of vessel density and FAZ-specific parameters to DR severity and BCVA

Teaching Note—Enhancing Social Work Education in Mental Health, Addictions, and Suicide Risk Assessment

Social workers play a critical role in assessing and treating individuals and families with mental health and addiction concerns. Although social workers are key professionals in the mental health workforce, there are gaps in the training and education of mental health, addictions, and suicide, and many students are inadequately prepared for field education. Simulation-based learning is an exemplar method of teaching and assessing practice competencies across several health-care professions including social work. This teaching note describes a simulation-based learning activity in which MSW students build competence in mental health, substance use, and suicide risk assessments with standardized clients. This innovation is integrated in a social work practice in mental health course and was developed in partnership with a community mental health and addiction treatment center. Through this partnership, we developed core competencies, case scenarios, as well as teaching resources and assessment instruments. An advisory committee consisting of MSW students, faculty members, and field instructors evaluated the simulation-based learning innovation and made recommendations for the next iteration. Implications for teaching social work practice in mental health are discussed