Does Eating a Meal before Testing Alter the Percent Body Fat Measurement Determined by Bioelectrical Impedance Analysis?

Please view abstract in the attached PDF file

Generalized Unitarity and Six-Dimensional Helicity

We combine the unitarity method with the six-dimensional helicity formalism of Cheung and O'Connell to construct loop-level scattering amplitudes. As a first example, we construct dimensionally regularized QCD one-loop four-point amplitudes. As a nontrivial multiloop example, we confirm that the recently constructed four-loop four-point amplitude of N=4 super-Yang-Mills theory, including nonplanar contributions, is valid for dimensions less than or equal to six. We comment on the connection of our approach to the recently discussed Higgs infrared regulator and on dual conformal properties in six dimensions.Comment: 38 pages, 7 figures, typos correcte

Does a Physical Education Bout Alter Percent Body Fat and the Adiposity Health Risk Classification When Using Leg-to-leg Bioelectrical Impedance Analysis in Girls?

Purpose: The purposes of this investigation were to determine: 1) whether a structured in-school physical education exercise bout altered percent body fat (%BF) determined by leg-to-leg bioelectrical impedance analysis (LBIA); and 2) whether the potential exercise-induced %BF magnitude of change altered the health risk classification of the child. Methods: Seventy-six girls (age: 12.2 ± 1.0 yr; height: 153.9 ± 7.5 cm; body mass: 51.9 ± 15.5 kg; BMI: 21.7 ± 5.4 kg/m2) participated in this investigation. LBIA measured %BF values were obtained immediately before and within five minutes after completing a structured, in-school, physical education class. Results: Significant reductions (p \u3c 0.0001) in mean %BF (25.0 ± 10.2 vs. 24.4 ± 10.3 %) were observed for the group following the physical education class. For the majority of the girls (88%), the %BF alteration was less than ± 2.0 %BF. More specifically, the %BF magnitude of change was ± 1.0 %BF in 64.5% of the girls, between 1.1 and 2.0 %BF in 23.7% of the girls, and by more than 2.0 %BF in 11.8% of the girls. Regardless of the %BF magnitude of change, all girls remained in the same adiposity classification category (healthy vs. unhealthy body fat) following exercise. Conclusion: Adhering to the pre-test exercise guideline appears unnecessary when using LBIA to categorize the health risk of an adolescent girl

The Relationship between Aerobic Capacity and Bone Health in Young Women

International Journal of Exercise Science 9(1): 56-63, 2016. The purpose of the present investigation was to examine the relationship between maximal oxygen consumption (VO2max) and bone health in young women. Eighty-three participants (age=21.0±2.2 years; BMI=22.4±3.0 kg/m2) reported for testing on two occasions separated by 48 hours. During visit 1 body composition assessment via dual-energy X-ray absorptiometry (DXA) and during visit 2, a VO2max test performed on a motorized treadmill. Weak correlations were found between absolute VO2max (L/min) and whole-body bone mineral density (WB-BMD: r=0.24, p=0.031) and whole-body bone mineral content (WB-BMC: r=0.37, p\u3c0.001). No relation between variables were observed when VO2max was expressed relative to body mass (mL/kg/min). Moderate correlations were observed between bone variables and body mass (WB-BMD: r=0.36, p\u3c0.001; WB-BMC: r=0.62, p\u3c0.001), fat-free mass (WB-BMD: r=0.45, p\u3c0.001; WB-BMC: r=0.54, p\u3c0.001), and fat mass (WB-BMD: r=0.31, p=0.004; WB-BMC: r=0.60, p\u3c0.001). Body mass, regardless of composition, was a stronger predictor of bone health than aerobic capacity in this sample of young women

Evaluation of Hand-to-Hand Bioelectrical Impedance Analysis for Estimating Percent Body Fat in Young Adults

Purposes were to (a) to examine the validity and precision of a hand-to-hand bioelectrical impedance analyzer (HBIA) and (b) to determine the effect of an acute sub-maximal aerobic exercise bout on HBIA percent body fat (%BF) measures. Forty-one young adults (21 women; 20 men) visited the laboratory for body composition assessment on two separate occasions. During the control session, %BF was assessed by HBIA twice, before and immediately after 30 min of rest, and once by air-displacement plethysmography (ADP), using the BOD POD, which was considered the criterion method for comparison. During the exercise session, HBIA %BF measurements were determined prior-to and immediately after 30 minutes of moderate-intensity treadmill exercise. HBIA significantly underestimated %BF in the total sample (mean difference (MD) = 1.4 ± 4.3%) and, when examined by gender, in the women (MD = 2.4 ± 4.1%). The standard errors of estimate (range 4.1-4.3%) also exceeded the recommended range for accuracy (\u3c3.5%). Following exercise, there was minimal, but statistically significant reduction in HBIA-measured %BF pre- to post-exercise for the total sample (19.6 ± 6.0 vs. 19.3 ± 6.0%; p = 0.011). HBIA underestimated %BF when compared to ADP and the individual prediction error exceeded current recommendations when assessing young adults. In addition, performing sub-maximal aerobic exercise prior to the assessment decreased the %BF estimate. When one factors the exercise-induced alterations with the currently observed tendency for HBIA to underestimate %BF, it is apparent that exercise may further reduce the accuracy of this method

The impact of body composition on energy expenditure during walking and running in young adults

The purpose of this study was to examine the impact of body composition on energy expenditure (EE) of 164 young adults during a 1-mile walk and a 1-mile run on a treadmill. Segmental bioimpedance was used to measure body composition variables. The EE in men (108.3 ± 17.6 kcal) was greater than (P \u3c 0.05) women (80.3 ± 10.6 kcal) during the 1-mile walk, and the difference increased in magnitude during the 1-mile run (144.9 ± 23.2 kcal vs. 105.1 ± 14.9 kcal, respectively). When EE was expressed per unit of body mass, men and women were similar. However, women had a higher EE per unit of fat-free mass (FFM). Regardless of gender, running 1-mile resulted in a greater EE than walking 1-mile. In addition, men expended more absolute calories than women due to a higher body mass. When EE was examined relative to FFM, women were found to be less economical than men, which was most likely due to carrying larger amounts of inactive adipose tissue

Why hyperbolic theories of dissipation cannot be ignored: Comments on a paper by Kostadt and Liu

Contrary to what is asserted in a recent paper by Kostadt and Liu ("Causality and stability of the relativistic diffusion equation"), experiments can tell apart (and in fact do) hyperbolic theories from parabolic theories of dissipation. It is stressed that the existence of a non--negligible relaxation time does not imply for the system to be out of the hydrodynamic regime.Comment: 8 pages Latex, to appear in Phys.Rev.

Aerodynamic roughness of glacial ice surfaces derived from high-resolution topographic data

This paper presents new methods of estimating the aerodynamic roughness (z0) of glacier ice directly from three-dimensional point clouds and digital elevation models (DEMs), examines temporal variability of z0, and presents the first fully distributed map of z0 estimates across the ablation zone of an Arctic glacier. The aerodynamic roughness of glacier ice surfaces is an important component of energy balance models and meltwater runoff estimates through its influence on turbulent fluxes of latent and sensible heat. In a warming climate these fluxes are predicted to become more significant in contributing to overall melt volumes. Ice z0 is commonly estimated from measurements of ice surface microtopography, typically from topographic profiles taken perpendicular to the prevailing wind direction. Recent advances in surveying permit rapid acquisition of high-resolution topographic data allowing revision of assumptions underlying conventional z0 measurement. Using Structure from Motion (SfM) photogrammetry with Multi-View Stereo (MVS) to survey ice surfaces with millimeter-scale accuracy, z0 variation over 3 orders of magnitude was observed. Different surface types demonstrated different temporal trajectories in z0 through 3 days of intense melt. A glacier-scale 2 m resolution DEM was obtained through terrestrial laser scanning (TLS), and subgrid roughness was significantly related to plot-scale z0. Thus, we show for the first time that glacier-scale TLS or SfM-MVS surveys can characterize z0 variability over a glacier surface potentially leading to distributed representations of z0 in surface energy balance models

The CoQ oxidoreductase FSP1 acts parallel to GPX4 to inhibit ferroptosis.

Ferroptosis is a form of regulated cell death that is caused by the iron-dependent peroxidation of lipids1,2. The glutathione-dependent lipid hydroperoxidase glutathione peroxidase 4 (GPX4) prevents ferroptosis by converting lipid hydroperoxides into non-toxic lipid alcohols3,4. Ferroptosis has previously been implicated in the cell death that underlies several degenerative conditions2, and induction of ferroptosis by the inhibition of GPX4 has emerged as a therapeutic strategy to trigger cancer cell death5. However, sensitivity to GPX4 inhibitors varies greatly across cancer cell lines6, which suggests that additional factors govern resistance to ferroptosis. Here, using a synthetic lethal CRISPR-Cas9 screen, we identify ferroptosis suppressor protein 1 (FSP1) (previously known as apoptosis-inducing factor mitochondrial 2 (AIFM2)) as a potent ferroptosis-resistance factor. Our data indicate that myristoylation recruits FSP1 to the plasma membrane where it functions as an oxidoreductase that reduces coenzyme Q10 (CoQ) (also known as ubiquinone-10), which acts as a lipophilic radical-trapping antioxidant that halts the propagation of lipid peroxides. We further find that FSP1 expression positively correlates with ferroptosis resistance across hundreds of cancer cell lines, and that FSP1 mediates resistance to ferroptosis in lung cancer cells in culture and in mouse tumour xenografts. Thus, our data identify FSP1 as a key component of a non-mitochondrial CoQ antioxidant system that acts in parallel to the canonical glutathione-based GPX4 pathway. These findings define a ferroptosis suppression pathway and indicate that pharmacological inhibition of FSP1 may provide an effective strategy to sensitize cancer cells to ferroptosis-inducing chemotherapeutic agents