Segmentation and Evaluation of Adipose Tissue from Whole Body MRI Scans

Accurate quantification of total body and the distribution of regional adipose tissue using manual segmentation is a challenging problem due to the high variation between manual delineations. Manual segmentation also requires highly trained experts with knowledge of anatomy. We present a hybrid segmentation method that provides robust delineation results for adipose tissue from whole body MRI scans. A formal evaluation of accuracy of the segmentation method is performed. This semi-automatic segmentation algorithm reduces significantly the time required for quantification of adipose tissue, and the accuracy measurements show that the results are close to the ground truth obtained from manual segmentations

A WARNING ABOUT USING PREDICTED VALUES TO ESTIMATE DESCRIPTIVE MEASURES

In a recent article in the Journal, Ogburn et al. highlighted the issues with using predicted values when estimating associations or effects. While the authors cautioned against using predicted values to estimate associations or effects, they noted that predictions can be useful for descriptive purposes. In this work, we highlight the issues with using individual-level predicted values to estimate population-level descriptive parameter

Polyacrylamide effects on infiltration in irrigated agriculture

Using polyacrylamide (PAM) following the NRCS conservation practice standard increases infiltration in furrow irrigation. PAM at 10 g in-' (10 ppm) during water advance nearly precludes detachment and transport of soil in furrows. If any sediment is entrained in the flow, it is readily flocculated in the presence of PAM and settles to the furrow-bottom in loose pervious structures. It was hypothesized that depositional surface seals that block pores are reduced or made more permeable with PAM. On Portneuf silt beams (coarse-silty, mixed, superactive, Durinodic Xeric Haplocalcid) furrow irrigation net infiltration increased 15%. Net increases on finer textured soils were generally higher. Furrow streams containing more than 5 g L (5,000 ppm) sediment reduced infiltration and infiltration rate more than fivefold compared to streams of clean water. Tension infiltrometry confirmed that PAM's maintenance of open pores to the furrow surface provides the infiltration increase mechanism. Infiltration rates at 40 and 100 min (1.6 and 3.9 inches) tension in PAM-treated furrows were double the rates of control furrows. Recirculating infiltrometer data showed a 30% infiltration increase with PAM use and infiltration was inversely related to maximum sediment concentration in the flow. Furrow inflow of 45 L min-1 (12 gal min-1 ) with PAM treatment decreased stream advance time 13% while reducing sediment loss 76% compared to untreated 23 L min-1 (6 gal min-1) inflows. Use of PAM in sprinkler irrigation streams reduced runoff 70% and sediment loss 75%, but tension infiltration measurements were inconsistent, suggesting changes in surface-sealing effects with sprinkler application of PAM are transient

Consistent Anisotropic Repulsions for Simple Molecules

We extract atom-atom potentials from the effective spherical potentials that suc cessfully model Hugoniot experiments on molecular fluids, e.g., $O_2$ and $N_2$. In the case of $O_2$ the resulting potentials compare very well with the atom-atom potentials used in studies of solid-state propertie s, while for $N_2$ they are considerably softer at short distances. Ground state (T=0K) and room temperatu re calculations performed with the new $N-N$ potential resolve the previous discrepancy between experimental and theoretical results.Comment: RevTeX, 5 figure

Missing Outcome Data in Epidemiologic Studies

Missing data are pandemic and a central problem for epidemiology. Missing data reduce precision and can cause notable bias. There remain too few simple published examples detailing types of missing data and illustrating their possible impact on results. Here we take an example randomized trial that was not subject to missing data and induce missing data to illustrate 4 scenarios in which outcomes are 1) missing completely at random, 2) missing at random with positivity, 3) missing at random without positivity, and 4) missing not at random. We demonstrate that accounting for missing data is generally a better strategy than ignoring missing data, which unfortunately remains a standard approach in epidemiology

Polyacrylamide (PAM) - A one million acre progress report

Water soluble polyacrylamide (PAM) was recognized in the early 1990s as an environmentally safe and highly effective erosion-preventing and infiltration-enhancing chemical, when applied in very dilute concentrations in furrow irrigation water (Lentz et al., 1992; Lentz and Sojka, 1994; McCutchan et al., 1994; Trout et al., 1995; Sojka and Lentz, 1997; Sojka et al., 1998a,b). The mode of action involves surface soil structure stabilization and maintenance of pore continuity. A recommended conservation practice standard was published by NRCS in 1995 (Anonymous, 1995) and is being revised in 1999. It delineates considerations and specifies methodology for. PAM-use. Commercial sales of erosion-preventing PAMs began in 1995. Approximately one million acres were treated in the United States in 1999. Extent of adoption of the practice outside the US is less certain, but interest is growing in several countries and continents. Key aspects of this PAM technology development are presented below

Evaluation of the prognostic value of computed tomography-derived body composition in patients undergoing endovascular aneurysm repair

Background: Endovascular aneurysm repair (EVAR) is the most common mode of repair of abdominal aortic aneurysms (AAA) in the UK. EVAR ranges from standard infrarenal repair to complex fenestrated and branched EVAR (F/B-EVAR). Sarcopenia is defined by lower muscle mass and function, which is associated with inferior perioperative outcomes. Computed tomography-derived body composition analysis offers prognostic value in patients with cancer. Several authors have evaluated the role of body composition analysis in predicting outcomes in patients undergoing EVAR; however, the evidence base is limited by heterogeneous methodology. Methods: Six hundred seventy-four consecutive patients (58 (8.6%) female, mean (SD) age 74.4 (6.8) years) undergoing EVAR and F/B-EVAR at three large tertiary centres were retrospectively recruited. Subcutaneous and visceral fat indices (SFI and VFI), psoas and skeletal muscle indices, and skeletal muscle density were measured at the L3 vertebral level from pre-operative computed tomographies. The maximally selected rank statistic technique was used to define optimal thresholds to predict mortality. Results: There were 191 deaths during the median follow-up period of 60.0 months. Mean (95% CI) survival in the low SMI versus high SMI subgroups was 62.6 (58.5–66.7) versus 82.0 (78.7–85.3) months (P < 0.001). Mean (95% CI) survival in the low SFI versus high SFI subgroups was 56.4 (48.2–64.7) versus 77.1 (74.2–80.1) months (P < 0.001). One-year mortality in the low SMI versus high SMI subgroups was 10% versus 3% (P < 0.001). Low SMI was associated with increased odds of one-year mortality (OR 3.19, 95% CI 1.60–6.34, P < 0.001). Five-year mortality in the low SMI versus high SMI subgroups was 55% versus 28% (P < 0.001). Low SMI was associated with increased odds of five-year mortality (OR 1.54, 95% CI 1.11–2.14, P < 0.01). On multivariate analysis of all patients, low SFI (HR 1.90, 95% CI 1.30–2.76, P < 0.001) and low SMI (HR 1.88, 95% CI 1.34–2.63, P < 0.001) were associated with poorer survival. On multivariate analysis of asymptomatic AAA patients, low SFI (HR 1.54, 95% CI 1.01–2.35, P < 0.05) and low SMI (HR 1.71, 95% CI 1.20–2.42, P < 0.01) were associated with poorer survival. Conclusions: Low SMI and SFI are associated with poorer long-term survival following EVAR and F/B-EVAR. The relationship between body composition and prognosis requires further evaluation, and external validation of the thresholds proposed in patients with AAA is required

Muon Track Reconstruction and Data Selection Techniques in AMANDA

The Antarctic Muon And Neutrino Detector Array (AMANDA) is a high-energy neutrino telescope operating at the geographic South Pole. It is a lattice of photo-multiplier tubes buried deep in the polar ice between 1500m and 2000m. The primary goal of this detector is to discover astrophysical sources of high energy neutrinos. A high-energy muon neutrino coming through the earth from the Northern Hemisphere can be identified by the secondary muon moving upward through the detector. The muon tracks are reconstructed with a maximum likelihood method. It models the arrival times and amplitudes of Cherenkov photons registered by the photo-multipliers. This paper describes the different methods of reconstruction, which have been successfully implemented within AMANDA. Strategies for optimizing the reconstruction performance and rejecting background are presented. For a typical analysis procedure the direction of tracks are reconstructed with about 2 degree accuracy.Comment: 40 pages, 16 Postscript figures, uses elsart.st

CAMELS-GB: hydrometeorological time series and landscape attributes for 671 catchments in Great Britain

We present the first large-sample catchment hydrology dataset for Great Britain, CAMELS-GB (Catchment Attributes and MEteorology for Large-sample Studies). CAMELS-GB collates river flows, catchment attributes and catchment boundaries from the UK National River Flow Archive together with a suite of new meteorological time series and catchment attributes. These data are provided for 671 catchments that cover a wide range of climatic, hydrological, landscape, and human management characteristics across Great Britain. Daily time series covering 1970–2015 (a period including several hydrological extreme events) are provided for a range of hydro-meteorological variables including rainfall, potential evapotranspiration, temperature, radiation, humidity, and river flow. A comprehensive set of catchment attributes is quantified including topography, climate, hydrology, land cover, soils, and hydrogeology. Importantly, we also derive human management attributes (including attributes summarising abstractions, returns, and reservoir capacity in each catchment), as well as attributes describing the quality of the flow data including the first set of discharge uncertainty estimates (provided at multiple flow quantiles) for Great Britain. CAMELS-GB (Coxon et al., 2020; available at https://doi.org/10.5285/8344e4f3-d2ea-44f5-8afa-86d2987543a9) is intended for the community as a publicly available, easily accessible dataset to use in a wide range of environmental and modelling analyses