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We present the requirements, design, and evaluation of the cryogenic continuously rotating half-wave plate (CHWP) for the Simons Observatory (SO). SO is a cosmic microwave background polarization experiment at Parque Astronómico de Atacama in northern Chile that covers a wide range of angular scales using both small (⌀0.42 m) and large (⌀6 m) aperture telescopes. In particular, the small aperture telescopes (SATs) focus on large angular scales for primordial B-mode polarization. To this end, the SATs employ a CHWP to modulate the polarization of the incident light at 8 Hz, suppressing atmospheric 1/f noise and mitigating systematic uncertainties that would otherwise arise due to the differential response of detectors sensitive to orthogonal polarizations. The CHWP consists of a 505 mm diameter achromatic sapphire HWP and a cryogenic rotation mechanism, both of which are cooled down to ∼50 K to reduce detector thermal loading. Under normal operation, the HWP is suspended by a superconducting magnetic bearing and rotates with a constant 2 Hz frequency, controlled by an electromagnetic synchronous motor. We find that the number of superconductors and the number of magnets that make up the superconducting magnetic bearing are important design parameters, especially for the rotation mechanism's vibration performance. The rotation angle is detected through an angular encoder with a noise level of 0.07 μrad s. During a cooldown process, the rotor is held in place by a grip-and-release mechanism that serves as both an alignment device and a thermal path. In this paper, we provide an overview of the SO SAT CHWP: its requirements, hardware design, and laboratory performance.

BackgroundWe aimed to understand the association between maternal stress in the first year of life and childhood body mass index (BMI) from 2 to 4 years of age in a large, prospective United States-based consortium of cohorts.MethodsWe used data from the Environmental influences on Child Health Outcomes program. The main exposure was maternal stress in the first year of life measured with the Perceived Stress Scale (PSS). The main outcome was the first childhood BMI percentile after age 2 until age 4 years. We used an adjusted linear mixed effects model to examine associations between BMI and PSS quartile.ResultsThe mean BMI percentile in children was 59.8 (SD 30) measured at 3.0 years (SD 1) on average. In both crude models and models adjusted for maternal BMI, age, race, ethnicity, infant birthweight, and health insurance status, no linear associations were observed between maternal stress and child BMI.ConclusionsAmong 1694 maternal-infant dyads, we found no statistically significant relationships between maternal perceived stress in the first year of life and child BMI after 2 through 4 years.ImpactAlthough existing literature suggests relationships between parental stress and childhood BMI, we found no linear associations between maternal stress in the first year of life and childhood BMI at 2-4 years of age among participants in ECHO cohorts. Higher maternal stress was significantly associated with Hispanic ethnicity, Black race, and public health insurance. Our analysis of a large, nationally representative sample challenges assumptions that maternal stress in the first year of life, as measured by a widely used scale, is associated with offspring BMI.

ObjectivesThe aim of the study was to examine self-rated health (SRH) of Middle Eastern immigrants in the US compared with US-born non-Hispanic whites and to examine factors associated with fair/poor SRH among Middle Eastern immigrants in the US.Study designWe used a cross-sectional design to analyze the National Health Interview Survey from 2001 to 2015.MethodsSecondary survey analysis procedures were conducted using the SAS program, with a total of 3,966 Middle Eastern and 731,285 US-born non-Hispanic whites. Descriptive statistics and regression analyses were used.ResultsMiddle Eastern immigrants had significantly higher rates of fair/poor SRH than US-born whites across the three survey waves. Reporting symptoms of serious psychological distress, older age (60+ years), current alcohol-drinking status, and having a family member with disability were the factors associated significantly with higher odds of reporting fair/poor SRH in Middle Eastern immigrants, whereas education was a protecting factor of fair/poor SRH.ConclusionsThis study indicates that Middle Eastern immigrants are one of the US immigrant populations that report poor health status, which reveals the need for health policy attention to reduce health disparities.

ObjectivesThe aim of the study was to examine self-rated health (SRH) of Middle Eastern immigrants in the US compared with US-born non-Hispanic whites and to examine factors associated with fair/poor SRH among Middle Eastern immigrants in the US.Study designWe used a cross-sectional design to analyze the National Health Interview Survey from 2001 to 2015.MethodsSecondary survey analysis procedures were conducted using the SAS program, with a total of 3,966 Middle Eastern and 731,285 US-born non-Hispanic whites. Descriptive statistics and regression analyses were used.ResultsMiddle Eastern immigrants had significantly higher rates of fair/poor SRH than US-born whites across the three survey waves. Reporting symptoms of serious psychological distress, older age (60+ years), current alcohol-drinking status, and having a family member with disability were the factors associated significantly with higher odds of reporting fair/poor SRH in Middle Eastern immigrants, whereas education was a protecting factor of fair/poor SRH.ConclusionsThis study indicates that Middle Eastern immigrants are one of the US immigrant populations that report poor health status, which reveals the need for health policy attention to reduce health disparities.

Single-molecule Förster resonance energy transfer (smFRET) is a powerful technique for nanometer-scale studies of single molecules. Solution-based smFRET, in particular, can be used to study equilibrium intra- and intermolecular conformations, binding/unbinding events and conformational changes under biologically relevant conditions without ensemble averaging. However, single-spot smFRET measurements in solution are slow. Here, we detail a high-throughput smFRET approach that extends the traditional single-spot confocal geometry to a multispot one. The excitation spots are optically conjugated to two custom silicon single photon avalanche diode (SPAD) arrays. Two-color excitation is implemented using a periodic acceptor excitation (PAX), allowing distinguishing between singly- and doubly-labeled molecules. We demonstrate the ability of this setup to rapidly and accurately determine FRET efficiencies and population stoichiometries by pooling the data collected independently from the multiple spots. We also show how the high throughput of this approach can be used o increase the temporal resolution of single-molecule FRET population characterization from minutes to seconds. Combined with microfluidics, this high-throughput approach will enable simple real-time kinetic studies as well as powerful molecular screening applications.

We optimized the performance of quantum-confined Stark effect (QCSE)-based voltage nanosensors. A high-throughput approach for single-particle QCSE characterization was developed and utilized to screen a library of such nanosensors. Type-II ZnSe/CdS-seeded nanorods were found to have the best performance among the different nanosensors evaluated in this work. The degree of correlation between intensity changes and spectral changes of the exciton's emission under an applied field was characterized. An upper limit for the temporal response of individual ZnSe/CdS nanorods to voltage modulation was characterized by high-throughput, high temporal resolution intensity measurements using a novel photon-counting camera. The measured 3.5 μs response time is limited by the voltage modulation electronics and represents ∼30 times higher bandwidth than needed for recording an action potential in a neuron.

Steven Weiss,1 Muhammad Qureshi2 1Quality and Support Services, Atlantic Dialysis Management Services, Ridgewood, New York, USA; 2Clinical Research, Mattoo & Bhat Medical Associates, P.C., College Point, New York, USACorrespondence: Steven WeissQuality and Support Services, Atlantic Dialysis Management Services, 385 Seneca Ave, Ridgewood, NY, 11385, USATel +1 347-512-9090Fax +1 718-366-2936Email sweiss@atlanticdialysis.comPurpose: Central line-associated bloodstream infection (CLABSI) is the second leading cause of death in hemodialysis patients. Patients dialyzed via central venous catheters (CVCs) are more susceptible to vascular access-related bloodstream infection (VRBSI), sepsis, and mortality when compared to patients with other dialysis accesses.Patients and Methods: A retrospective observational data analysis was conducted from 13 outpatient dialysis clinics in the United States to compare novel chlorhexidine-coated end caps to standard needlefree connectors for differences in CLABSI rates when utilizing CVCs for hemodialysis. There were two periods in this study: in the first study period over a 5-month period (May 2018 to September 2018), data were evaluated from a group of patients undergoing hemodialysis using chlorhexidine end-caps (‘chlorhexidine group’) as well as a group using standard needlefree connectors (‘standard group’). An initial assessment found that a substantial CLABSI rate reduction was seen with use of chlorhexidine-coated end caps; therefore, most patients were switched to chlorhexidine by February 2019 and data continued to be collected till June 2019. The second study period spanned 9 months from October 2018 to June 2019.Results: Across 13 dialysis centers, anonymized health records of 5934 patients who were dialyzed via CVCs between May 2018 and June 2019 were analyzed. The mean age was 61.3 and 47.1% of all patients were female. Study period one included 967 patients with chlorhexidine and 1044 patients with standard end caps, while there were 3647 chlorhexidine and 276 standard patients in the second period. The combined CLABSI rate in the chlorhexidine group was 0.09/1000 CVC days versus 0.63/1000 CVC days in the standard group (p< 0.0001).Conclusion: Chlorhexidine-coated CVC caps may provide a therapeutic improvement in CVC hemodialysis management.Keywords: catheter-related infection, renal dialysis, quality improvement, infection control, chronic kidney failure, chlorhexidine-coated CVC caps

We describe an 8-spot confocal setup for high-throughput smFRET assays and illustrate its performance with two characteristic experiments. First, measurements on a series of freely diffusing doubly-labeled dsDNA samples allow us to demonstrate that data acquired in multiple spots in parallel can be properly corrected and result in measured sample characteristics identical to those obtained with a standard single-spot setup. We then take advantage of the higher throughput provided by parallel acquisition to address an outstanding question about the kinetics of the initial steps of bacterial RNA transcription. Our real-time kinetic analysis of promoter escape by bacterial RNA polymerase confirms results obtained by a more indirect route, shedding additional light on the initial steps of transcription. Finally, we discuss the advantages of our multispot setup, while pointing potential limitations of the current single laser excitation design, as well as analysis challenges and their solutions.

Nitrogen (N) pollution is increasingly recognized as a threat to biodiversity. However, our understanding of how N is affecting vulnerable species across taxa and broad spatial scales is limited. We surveyed approximately 1400 species in the continental United States listed as candidate, threatened, or endangered under the US Endangered Species Act (ESA) to assess the extent of recognized N-pollution effects on biodiversity in both terrestrial and aquatic ecosystems. We found 78 federally listed species recognized as affected by N pollution. To illustrate the complexity of tracing N impacts on listed species, we describe an interdisciplinary case study that addressed the threat of N pollution to California Bay Area serpentine grasslands. We demonstrate that N pollution has affected threatened species via multiple pathways and argue that existing legal and policy regulations can be applied to address the biodiversity consequences of N pollution in conjunction with scientific evidence tracing N impact pathways.

We introduce Photon-HDF5, an open and efficient file format to simplify exchange and long term accessibility of data from single-molecule fluorescence experiments based on photon-counting detectors such as single-photon avalanche diode (SPAD), photomultiplier tube (PMT) or arrays of such detectors. The format is based on HDF5, a widely used platform- and language-independent hierarchical file format for which user-friendly viewers are available. Photon-HDF5 can store raw photon data (timestamp, channel number, etc) from any acquisition hardware, but also setup and sample description, information on provenance, authorship and other metadata, and is flexible enough to include any kind of custom data. The format specifications are hosted on a public website, which is open to contributions by the biophysics community. As an initial resource, the website provides code examples to read Photon-HDF5 files in several programming languages and a reference python library (phconvert), to create new Photon-HDF5 files and convert several existing file formats into Photon-HDF5. To encourage adoption by the academic and commercial communities, all software is released under the MIT open source license.