Towards Rapid Parameter Estimation on Gravitational Waves from Compact Binaries using Interpolated Waveforms

Accurate parameter estimation of gravitational waves from coalescing compact binary sources is a key requirement for gravitational-wave astronomy. Evaluating the posterior probability density function of the binary's parameters (component masses, sky location, distance, etc.) requires computing millions of waveforms. The computational expense of parameter estimation is dominated by waveform generation and scales linearly with the waveform computational cost. Previous work showed that gravitational waveforms from non-spinning compact binary sources are amenable to a truncated singular value decomposition, which allows them to be reconstructed via interpolation at fixed computational cost. However, the accuracy requirement for parameter estimation is typically higher than for searches, so it is crucial to ascertain that interpolation does not lead to significant errors. Here we provide a proof of principle to show that interpolated waveforms can be used to recover posterior probability density functions with negligible loss in accuracy with respect to non-interpolated waveforms. This technique has the potential to significantly increase the efficiency of parameter estimation.Comment: 7 pages, 2 figure

Geogenomic segregation and temporal trends of human pathogenic Escherichia coli o157:H7, Washington, USA, 2005-2014

The often-noted and persistent increased incidence of Escherichia coli O157:H7 infections in rural areas is not well understood. We used a cohort of E. coli O157:H7 cases reported in Washington, USA, during 2005–2014, along with phylogenomic characterization of the infecting isolates, to identify geographic segregation of and temporal trends in specific phylogenetic lineages of E. coli O157:H7. Kernel estimation and generalized additive models demonstrated that pathogen lineages were spatially segregated during the period of analysis and identified a focus of segregation spanning multiple, predominantly rural, counties for each of the main clinical lineages, Ib, IIa, and IIb. These results suggest the existence of local reservoirs from which humans are infected. We also noted a secular increase in the proportion of lineage IIa and IIb isolates. Spatial segregation by phylogenetic lineage offers the potential to identify local reservoirs and intervene to prevent continued transmission

A new spatially and temporally variable sigma parameter in degree-day melt modelling of the Greenland Ice Sheet 1870–2013

The degree-day based method of calculating ice-/snow-melt across the Greenland Ice Sheet (GrIS) commonly includes the temperature parameter sigma (σ) accounting for temperature variability on short (sub-monthly down to hourly) timescales, in order to capture melt in months where the mean temperature is below 0 °C. Sigma is typically assumed to be constant in space and time, with values ranging from ~ 2.5 to 5.5 °C. It is unclear in many cases how these values were derived and little sensitivity analysis or validation has been conducted. Here we determine spatially and temporally varying monthly values of σ for the unique, extended 1870–2013 timescale based on downscaled, corrected European Centre for Medium-Range Weather Forecasts (ECMWF) Interim (ERA-I) and Twentieth Century Reanalysis (20CR) meteorological reanalysis 2 m air temperatures on a 5 km × 5 km polar stereographic grid for the GrIS. The resulting monthly σ values reveal a distinct seasonal cycle. The mean summer σ value for the study period is ~ 3.2 °C, around 1 °C lower than the value of 4.2 °C commonly used in the literature. Sigma values for individual summers range from 1.7 to 5.9 °C. Since the summer months dominate the melt calculation, use of the new variable σ parameter would lead to a smaller melt area and a more positive surface mass balance for the GrIS. Validation of our new variable σ dataset shows good agreement with standard deviations calculated from automatic weather station observations across the ice sheet. Trend analysis shows large areas of the ice sheet exhibit statistically significant increasing temperature variability from 1870–2013 in all seasons, with notable exceptions around Summit in spring, and Summit and South Dome in winter. More recently, since 1990, σ has been decreasing, significantly so in the north-west during July. These interannual σ trends reflect climate change and variability processes operating across the ice sheet, several mechanisms of which are briefly discussed

Rapidly evaluating the compact-binary likelihood function via interpolation

Bayesian parameter estimation on gravitational waves from compact-binary coalescences (CBCs) typically requires millions of template waveform computations at different values of the parameters describing the binary. Sampling techniques such as Markov chain Monte Carlo and nested sampling evaluate likelihoods and, hence, compute template waveforms, serially; thus, the total computational time of the analysis scales linearly with that of template generation. Here we address the issue of rapidly computing the likelihood function of CBC sources with nonspinning components. We show how to efficiently compute the continuous likelihood function on the three-dimensional subspace of parameters on which it has a nontrivial dependence—the chirp mass, symmetric mass ratio and coalescence time—via interpolation. Subsequently, sampling this interpolated likelihood function is a significantly cheaper computational process than directly evaluating the likelihood; we report improvements in computational time of two to three orders of magnitude while keeping likelihoods accurate to ≲0.025%. Generating the interpolant of the likelihood function over a significant portion of the CBC mass space is computationally expensive but highly parallelizable, so the wall time can be very small relative to the time of a full parameter-estimation analysis

Development of a Symptom Management Intervention: Qualitative Feedback from Advanced Lung Cancer Patients and their Family Caregivers

Background: Little is known about cancer patient and family caregiver preferences for the content and format of nonpharmacologic interventions. Revising interventions based on patient and caregiver feedback before implementation may improve intervention feasibility and acceptability, especially in the context of advanced-stage cancer. Objectives: The aim of the study was to obtain feedback from patients with advanced-stage, symptomatic lung cancer and their family caregivers on the content and format of a nonpharmacologic symptom management intervention under development. The intervention blended evidence-based cognitive-behavioral and emotion-focused strategies to reduce physical and psychological symptoms. Methods: Semistructured qualitative interviews were conducted with 21 patients with advanced-stage, symptomatic lung cancer and caregivers. Participants reviewed handouts regarding intervention components and provided feedback. Results: Patients and caregivers desired intervention components that addressed the patient's high symptom burden such as education regarding treatment adverse effects and the provision of various coping tools. Offering interventions with a brief or flexible length and delivering them via telephone were other suggestions for enhancing intervention acceptability. Participants also preferred an equal focus on patient and caregiver concerns and a more positive intervention framework. Conclusions: Intervention preferences of patients with advanced-stage lung cancer and caregivers underscore the severity of the disease and treatment process and the need to adapt interventions to patients with high symptom burden. These preferences may be incorporated into future intervention trials to improve participant recruitment and retention. Implications for Practice: Nurses can modify interventions to meet the needs of patients with advanced-stage, symptomatic lung cancer and caregivers. For example, flexibility regarding intervention content and length may accommodate those with significant symptoms

Coping with physical and psychological symptoms: a qualitative study of advanced lung cancer patients and their family caregivers

PURPOSE: Advanced lung cancer patients have high rates of multiple physical and psychological symptoms, and many of their family caregivers experience significant distress. However, little is known about strategies that these patients and their family caregivers employ to cope with physical and psychological symptoms. This study aimed to identify strategies for coping with various physical and psychological symptoms among advanced, symptomatic lung cancer patients and their primary family caregivers. METHODS: Patients identified their primary family caregiver. Individual semi-structured qualitative interviews were conducted with 21 advanced, symptomatic lung cancer patients and primary family caregivers. Thematic analysis of interview data was framed by stress and coping theory. RESULTS: Patients and caregivers reported maintaining a normal routine and turning to family and friends for support with symptom management, which often varied in its effectiveness. Whereas support from health-care professionals and complementary and alternative medicine were viewed favorably, reactions to Internet and in-person support groups were mixed due to the tragic nature of participants' stories. Several cognitive coping strategies were frequently reported (i.e., changing expectations, maintaining positivity, and avoiding illness-related thoughts) as well as religious coping strategies. CONCLUSIONS: Results suggest that advanced lung cancer patients and caregivers may be more receptive to cognitive and religious approaches to symptom management and less receptive to peer support. Interventions should address the perceived effectiveness of support from family and friends

Global urinary volatolomics with (GC×)GC-TOF-MS

Urinary volatolomics offers a noninvasive approach for disease detection and monitoring. Herein we present an improved methodology for global volatolomic profiling. Wide coverage was achieved by utilizing a multiphase sorbent for volatile organic compound (VOC) extraction. A single, midpolar column gas chromatography (GC) assay yielded substantially higher numbers of monitored VOCs compared to our previously reported single-sorbent method. Multidimensional GC (GC×GC) enhanced further biomarker discovery while data analysis was simplified by using a tile-based approach. At the same time, the required urine volume was reduced 5-fold from 2 to 0.4 mL. The applicability of the methodology was demonstrated in a pancreatic ductal adenocarcinoma cohort where previous findings were confirmed while a series of additional VOCs with diagnostic potential were discovered

The long exercise test as a functional marker of periodic paralysis

Aims: The aim of this study was to evaluate the sensitivity of the long exercise test (LET) in the diagnosis of periodic paralysis (PP) and assess correlations with clinical phenotypes and genotypes. // Methods: From an unselected cohort of 335 patients who had an LET we analyzed 67 patients with genetic confirmation of PP and/or a positive LET. // Results: 32/45 patients with genetically confirmed PP had a significant decrement after exercise (sensitivity of 71%). Performing the short exercise test before the LET in the same hand confounded results in four patients. Sensitivity was highest in patients with frequent (daily or weekly) attacks (8/8, 100%), intermediate with up to monthly attacks (15/21, 71%) and lowest in those with rare attacks (9/16, 56%) (p = .035, Mann–Whitney U-test). Patients with a positive LET without confirmed PP mutation comprised those with typical PP phenotype and a group with atypical features. // Discussion: In our cohort, the LET is strongly correlated with the frequency of paralytic attacks suggesting a role as a functional marker. A negative test in the context of frequent attacks makes a diagnosis of PP unlikely but it does not rule out the condition in less severely affected patients