Estimation from quantized Gaussian measurements: when and how to use dither

Subtractive dither is a powerful method for removing the signal dependence of quantization noise for coarsely quantized signals. However, estimation from dithered measurements often naively applies the sample mean or midrange, even when the total noise is not well described with a Gaussian or uniform distribution. We show that the generalized Gaussian distribution approximately describes subtractively dithered, quantized samples of a Gaussian signal. Furthermore, a generalized Gaussian fit leads to simple estimators based on order statistics that match the performance of more complicated maximum likelihood estimators requiring iterative solvers. The order statistics-based estimators outperform both the sample mean and midrange for nontrivial sums of Gaussian and uniform noise. Additional analysis of the generalized Gaussian approximation yields rules of thumb for determining when and how to apply dither to quantized measurements. Specifically, we find subtractive dither to be beneficial when the ratio between the Gaussian standard deviation and quantization interval length is roughly less than one-third. When that ratio is also greater than 0.822/K^0.930 for the number of measurements K > 20, estimators we present are more efficient than the midrange.https://arxiv.org/abs/1811.06856Accepted manuscrip

Dead Time Compensation for High-Flux Ranging

Dead time effects have been considered a major limitation for fast data acquisition in various time-correlated single photon counting applications, since a commonly adopted approach for dead time mitigation is to operate in the low-flux regime where dead time effects can be ignored. Through the application of lidar ranging, this work explores the empirical distribution of detection times in the presence of dead time and demonstrates that an accurate statistical model can result in reduced ranging error with shorter data acquisition time when operating in the high-flux regime. Specifically, we show that the empirical distribution of detection times converges to the stationary distribution of a Markov chain. Depth estimation can then be performed by passing the empirical distribution through a filter matched to the stationary distribution. Moreover, based on the Markov chain model, we formulate the recovery of arrival distribution from detection distribution as a nonlinear inverse problem and solve it via provably convergent mathematical optimization. By comparing per-detection Fisher information for depth estimation from high- and low-flux detection time distributions, we provide an analytical basis for possible improvement of ranging performance resulting from the presence of dead time. Finally, we demonstrate the effectiveness of our formulation and algorithm via simulations of lidar ranging.Comment: Revision with added estimation results, references, and figures, and modified appendice

Evaluating Study Procedure Training Methods for a Remote Daily Diary Study of Sexual Minority Women

Background: Ecological momentary assessment (EMA) methods can be used to remotely assess physical and mental health in daily life for hard-to-reach, marginalized, and geographically dispersed populations in the U.S., such as sexual minority women (e.g., lesbian, bisexual). However, EMA studies are often complex, and engaging participants from afar can be a challenge. This study experimentally examined whether adding videos to written recruitment materials would improve consent rates, reduce dropout rates, and improve survey completion rates for an online daily diary study. Methods: As part of a 2-week study of same-sex female couples\u27 health, 376 women ages 18-35 were recruited from across the U.S. using a market research firm. Couples were randomized to an introductory information condition (written + video materials or written-only materials) prior to informed consent. Results: Overall, 97.1% of eligible women reviewed introductory materials and of these 96.7% consented; consent rates did not differ by condition (written + video: 97.1%, written-only: 97.1%). Dropout rates were low (5.4%) and survey completion rates were high (90.4% of surveys completed); there were no group differences for study dropout (written + video: 3.6%, written-only: 7.0%) or survey completion (written + video: 92.5%, written-only: 88.4%). Data from women randomized to receive videos indicated more than half (53.3%) did not watch any of the five videos in full. However, among those who viewed the videos, time spent watching videos, watching more videos in full, and watching at least one video in full were each positive associated with survey completion rates. Conclusions: In summary, we had high consent rates, low dropout rates, and high survey completion rates regardless of video instructions. Although sexual minority women can be hard to reach, our potential participants appeared highly motivated to take part in research, and thus video recruitment materials were not necessary to improve participation. Future experimental research to maximize EMA study design and implementation could be important for populations less inclined to participate in EMA studies, or who are less familiar with research

Refining an Ecological Momentary Assessment Study of Binge Eating Among Sexual Minority and Heterosexual Young Women: A Mixed Methods Pilot Study

Background: Ecological momentary assessment (EMA) is used to capture daily lived experiences, states, and environments. Although EMA is commonly used in behavioral health research, there remains a dearth of literature on how researchers account for design considerations of EMA techniques when designing studies. The goal of this formative mixed methods study was to elicit feedback on EMA study procedures and materials from the target populations for a larger study about binge eating among sexual minority and heterosexual young women, in which data are collected entirely remotely. Methods: Sexual minority (n=12) and heterosexual (n=9) women ages 18–30 who binge ate took part in a pilot EMA study and exit interview and survey. As part of the consent and orientation process, participants reviewed video and written materials describing the study purpose and procedures. Using a smartphone app, for seven consecutive days they completed a survey each morning, 5 random surveys per day, and self-initiated a survey each time they binge ate. Participants then provided feedback on the study via a 1-hour virtual interview and online survey. Interviews were transcribed and reviewed by two coders to identify themes on the acceptability and feasibility of the EMA procedures with a focus on: (I) the training and study description materials; (II) general smartphone app and survey preferences; and (III) specific EMA survey question content and wording. Results: The qualitative and quantitative data converged to suggest participants were able to easily download and use the app to complete surveys and report on binge eating events. Participants provided feedback that was incorporated into revisions on general study procedures, the training video content, and EMA question content for binge eating, identity-related stressors, and appearance-related pressures. No systematic themes in the quantitative or qualitative data emerged to suggest questions were perceived differently by sexual minority and heterosexual young women. Conclusions: These findings provide evidence for the feasibility of conducting a remote EMA study to assess young women’s experiences around binge eating. This formative study provides an example of how a mixed methods approach can be used to refine EMA study methods and questions to improve study design

Projecting the effect of crop yield increases, dietary change and different price scenarios on land use under two different state security regimes

Peer reviewedPublisher PD

Rationale and Design of an Ecological Momentary Assessment Study Examining Predictors of Binge Eating Among Sexual Minority and Heterosexual Young Women: Protocol for the Health and Experiences in Real Life (HER Life) Study

Background: Previous research has identified health disparities between sexual minority and heterosexual women, including increased rates of obesity and binge eating in sexual minority women. Established predictors of binge eating behavior include negative emotions and sociocultural processes; however, these studies are generally conducted in samples of young women where sexual identity is not known or reported. There is a dearth of research evaluating how sexual minority–specific factors (eg, minority stress and connectedness to the lesbian, gay, bisexual, transgender, and queer community) may affect binge eating in sexual minority women. In addition, no studies have examined these processes in racially diverse samples or considered how intersecting minority identities (eg, Black and sexual minority) may affect eating behaviors. Objective: The Health and Experiences in Real Life (HER Life) Project aims to clarify real-world predictors of binge eating in young heterosexual and sexual minority women using ecological momentary assessment. The role of affective, social, and health behavior factors in binge eating will be examined for all women (aim 1), and sexual minority–specific predictors will also be considered for sexual minority women participants (aim 2). Person-level moderators of race, body- and eating-related factors, and sexual minority–specific factors will also be examined to better understand how real-world binge eating predictors may differ for various demographic groups (aim 3). Methods: Researchers aim to recruit 150 sexual minority and 150 heterosexual women from across the United States, including at least 50 Black women for each group, using web-based recruitment methods. The eligibility criteria include identifying as a woman, being aged between 18 and 30 years, and having had at least two binge eating episodes in the last 2 weeks. Participants must endorse being only or mostly attracted to men (considered heterosexual) or only or mostly attracted to women or having a current or most recent female partner (considered sexual minority). Eligible participants complete an initial web-based baseline survey and then 14 days of ecological momentary assessment involving the completion of a morning and before-bed survey and 5 prompted surveys per day as well as a user-initiated survey after binge eating episodes. The data will be analyzed using a series of multilevel models. Results: Data collection started in February 2021. We have currently enrolled 129 sexual minority women and 146 heterosexual women. Data collection is expected to conclude in fall 2022. Conclusions: The Health and Experiences in Real Life Project aims to elucidate potential differences between sexual minority and heterosexual women in within-person factors predicting binge eating and inform eating disorder interventions for sexual minority women. The challenges in recruiting sexual minority women, including the determination of eligibility criteria and considerations for remote data collection, are discussed. International Registered Report Identifier (IRRID): DERR1-10.2196/4119

Source Mechanism of Small Long-Period Events at Mount St. Helens in July 2005 Using Template Matching, Phase-Weighted Stacking, and Full-Waveform Inversion

Long-period (LP, 0.5-5 Hz) seismicity, observed at volcanoes worldwide, is a recognized signature of unrest and eruption. Cyclic LP “drumbeating” was the characteristic seismicity accompanying the sustained dome-building phase of the 2004–2008 eruption of Mount St. Helens (MSH), WA. However, together with the LP drumbeating was a near-continuous, randomly occurring series of tiny LP seismic events (LP “subevents”), which may hold important additional information on the mechanism of seismogenesis at restless volcanoes. We employ template matching, phase-weighted stacking, and full-waveform inversion to image the source mechanism of one multiplet of these LP subevents at MSH in July 2005. The signal-to-noise ratios of the individual events are too low to produce reliable waveform inversion results, but the events are repetitive and can be stacked. We apply network-based template matching to 8 days of continuous velocity waveform data from 29 June to 7 July 2005 using a master event to detect 822 network triggers. We stack waveforms for 359 high-quality triggers at each station and component, using a combination of linear and phase-weighted stacking to produce clean stacks for use in waveform inversion. The derived source mechanism points to the volumetric oscillation (∼10 m3) of a subhorizontal crack located at shallow depth (∼30 m) in an area to the south of Crater Glacier in the southern portion of the breached MSH crater. A possible excitation mechanism is the sudden condensation of metastable steam from a shallow pressurized hydrothermal system as it encounters cool meteoric water in the outer parts of the edifice, perhaps supplied from snow melt

The effects of a protein enriched diet with lean red meat combined with a multi-modal exercise program on muscle and cognitive health and function in older adults: study protocol for a randomised controlled trial

BACKGROUND: Age-related muscle wasting has been strongly implicated with falls and fractures in the elderly, but it has also been associated with cognitive decline and dementia. Progressive resistance training (PRT) and adequate dietary protein are recognised as important contributors to the maintenance of muscle health and function in older adults. However, both factors also have the potential to improve brain function and prevent cognitive decline via several pathways, including the regulation of various growth and neurotrophic factors [insulin-like growth factor-1 (IGF-1)]; brain-derived growth factor (BDNF)] and/or the modulation of systemic inflammation. The primary aim of this study is to investigate whether a modest increase in dietary protein achieved through the consumption of lean red meat three days per week, when combined with PRT, can enhance muscle mass, size and strength and cognitive function in community-dwelling older people. METHODS/DESIGN: The study design is a 48-week randomised controlled trial consisting of a 24-week intervention with a 24-week follow-up. Men and women (n=152) aged 65 years and over residing in the community will be randomly allocated to: 1) PRT and provided with 220 g (raw weight) of lean red meat to be cooked and divided into two 80 g servings on each of the three days that they complete their exercise session, or 2) control PRT in which participants will be provided with and advised to consume ≥1 serving (~1/2 cup) of rice and/or pasta or 1 medium potato on each of the three training days. The primary outcome measures will be muscle mass, size and strength and cognitive function. Secondary outcomes will include changes in: muscle function, neural health (corticospinal excitability and inhibition and voluntary activation), serum IGF-1 and BDNF, adipokines and inflammatory markers, fat mass and inter-/intra-muscular fat, blood pressure, lipids and health-related quality of life. All outcome measures will be assessed at baseline and 24 weeks, with the exception of cognitive function and the various neurobiological and inflammatory markers which will also be assessed at week 12. DISCUSSION: The findings from this study will provide important new information on whether a modest increase in dietary protein achieved through the ingestion of lean red meat can enhance the effects of PRT on muscle mass, size and strength as well as cognitive function in community-dwelling older adults. If successful, the findings will form the basis for more precise exercise and nutrition guidelines for the management and prevention of age-related changes in muscle and neural health and cognitive function in the elderly. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12613001153707 . Date registered 16(th) October, 2013

The discovery of an M4+T8.5 binary system

The original article can be found at: http://www3.interscience.wiley.com Copyright Blackwell Publishing / Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.14620.xWe report the discovery of a T8.5 dwarf, which is a companion to the M4 dwarf Wolf 940. [Please see original online abstract for complete version with correct notation]Peer reviewe

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13