Reliability of the Omron HBF-500 Body Composition Monitor

The Omron HBF-500 incorporates both hand-to-hand and foot-to-foot electrical impedance technology. At this time, the authors are not aware of any studies examining the consistency of this monitor. PURPOSE: To assess the reliability of the Omron HBF-500 body composition monitor. METHODS: Twelve men and six women signed an informed consent and participated in the study (32.4±8.7 years, 169.9±7.5 cm, 81.4±15.9 kg, 28.2±5.5 kg.m-2). Participants reported to the laboratory on three separate occasions separated by at least one day and within one week. Participants were asked to refrain from exercise and caffeine on the days of testing and, were asked to not eat a heavy meal three hours prior and to remain normally hydrated. For each trial, height was measured on a Seca 214 portable height rod (Hamburg, Germany) and weight on a Detecto DR 400 digital platform scale (Webb City, MO) without shoes or socks and with one layer of light clothing. Participants then had their body weight and body fat percent (BF%) assessed on the Omron HBF-500 body composition monitor. On the second day of testing, body BF% was also assessed using a Biodynamics 450 bioimpedance analyzer (Seattle, WA). RESULTS: There were no significant differences between the trials for weight assessed on the digital platform scale, F(2,17) = 1.2, p = 0.308, and on the Omron HBF-500, F(2,17) = 2.6, p = 0.086 (Table 1). There were also no significant differences between the trials for body fat assessed on the Omron F(2,17) = 1.0, p = 0.351. Reliability assessed with Cronbach’s alpha was high between the trials of each of the measures (Digital scale (kg), α = 0.999, Omron (kg), α = 0.999, Omron (BF%), α = 0.998). A dependent t-test indicated a significant difference in BF% between the Omron and Biodynamics analyzer (34.2±9.6 and 38.8±12.8, respectively), t(15) = -2.9, p = 0.011. Finally, dependent t-tests revealed body weight measured by the Omron was significantly greater than the Detecto scale in trial 2, t(17) = -6.9, p = 0.001, and in trial 3, t(17) = -7.9, p = 0.001. CONCLUSIONS: The Omron HBF-500 seems to consistently measure body weight and body composition. Although the HBF-500 can be questioned as an accurate measure of body composition, it seems to be a useful tool if one is interested in tracking changes in body weight and BF%

Accuracy of the Omron HBF-500 Body Composition Monitor in Male and Female College Students

The Omron HBF-500 is an inexpensive body composition monitor that incorporates both hand-to-hand and foot-to-foot electrical impedance technology. At this time, studies examining the accuracy of the HBF-500 when estimating percent body fat (%BF) are scarce and if this instrument gains popularity due to its claimed precision, comparisons against validated techniques should be conducted. The purpose of this study was to assess the accuracy of the Omron HBF-500 body composition monitor using the BOD POD as a criterion. Forty-eight men and 33 women participated in the study (24.3±6.9 years, 171.0±10.0 cm, 78.4±18.0 kg, 26.6±5.1 kg/m2). Participants were asked to refrain from exercise and caffeine on the day of testing, not eat a heavy meal three hours prior to measurement (a meal that would typically constitute breakfast, lunch or dinner), and to remain normally hydrated. Participants removed all jewelry and garments down to skintight clothing such as swimsuits or cycling shorts and were assessed on the BOD POD and Omron according to manufacturer’s guidelines. The Omron significantly overestimated %BF compared to the BOD POD in males (24.4±8.0 % and 22.9±9.1 %, respectively), and females (35.5±7.7 % and 30.1±7.9 %), p = .001. The Omron was significantly correlated with the BOD POD when assessing body fat, r= .95. The estimates of %BF produced by the BOD POD and HBF-500 differ considerably. Consequently, caution should be taken when using the Omron HBF-500 as a measure of body fat. However, given the difference of only 1.5% BF between the two methods, perhaps males could use the HBF-500 to gain a general idea of body composition status. For females, the degree of overestimation is too high to be suitable for this purpose and incorrect categorization of %BF status could result. In cases where an accurate estimate of %BF is crucial, using a more established method than the Omron is recommended

Laboratory observation of a nonlinear interaction between shear Alfv\'{e}n waves

An experimental investigation of nonlinear interactions between shear Alfv\'{e}n waves in a laboratory plasma is presented. Two Alfv\'{e}n waves, generated by a resonant cavity, are observed to beat together, driving a low frequency nonlinear psuedo-mode at the beat frequency. The psuedo-mode then scatters the Alfv\'{e}n waves, generating a series of sidebands. The observed interaction is very strong, with the normalized amplitude of the driven psuedo-mode comparable to the normalized magnetic field amplitude ($\delta B/B$) of the interacting Alfv\'{e}n waves.Comment: 10 pages, 4 figures, submitted to Phys. Rev. Let

Laboratory measurements of electrostatic solitary structures generated by electron beam injection

Electrostatic solitary structures are generated by injection of a suprathermal electron beam parallel to the magnetic field in a laboratory plasma. Electric microprobes with tips smaller than the Debye length ($\lambda_{De}$) enabled the measurement of positive potential pulses with half-widths 4 to 25$\lambda_{De}$ and velocities 1 to 3 times the background electron thermal speed. Nonlinear wave packets of similar velocities and scales are also observed, indicating that the two descend from the same mode which is consistent with the electrostatic whistler mode and result from an instability likely to be driven by field-aligned currents.Comment: 5 pages, 4 figures http://link.aps.org/doi/10.1103/PhysRevLett.105.11500

Accuracy of the Omron HBF-500 Body Composition Monitor

The Omron HBF-500 is a relatively new and inexpensive body composition monitor that incorporates both hand-to-hand and foot-to-foot electrical impedance technology. At this time, the authors are not aware of any studies examining the accuracy of this monitor. PURPOSE: To assess the accuracy of the Omron HBF-500 body composition monitor using the BOD POD as a criterion. METHODS: Sixteen men and 23 women signed an informed consent and participated in the study (22.7±3.7 years, 168.8±9.1 cm, 73.8±17.8 kg, 25.7±5.6 kg.m-2). Participants were asked to refrain from exercise and caffeine on the day of testing, and were asked not eat a heavy meal three hours prior and to remain normally hydrated. Participants removed all jewelry and garments down to tight fitting clothing (swim suits or running tights) and were assessed on the BOD POD and Omron according to manufacturer’s guidelines. RESULTS: The Omron HBF-500 significantly overestimated percent body fat (%BF) by 3.5% compared to the BOD POD (31.7±9.6% and 28.6±9.6%, respectively), t(38) = -6.05, p = 0.001. The Omron HBF-500 also measured weight significantly higher than the BODPOD (74.4±17.7kg and 73.8±17.8kg, respectively), t(38) = -11.2, p = 0.001. Finally, the Omron HBF-500 was significantly correlated with the BOD POD when assessing body fat, r = .93. CONCLUSIONS: Caution should be taken when using the Omron HBF-500 as a measure of body fat. Those who choose to use this instrument should be aware the 3.5% higher reading compared to the BOD POD

Experimental Study of Convective Cells and RF Sheaths Ex- cited by a Fast Wave Antenna in the LAPD

C

Ion acoustic wave experiments in a high school plasma physics laboratory

We describe a successful alliance between a university and several high schools. The alliance is centered on a laboratory experiment constructed by students and faculty. The experiment involves sophisticated concepts and equipment not readily available in high schools. Much of the experiment is directly related to the science and mathematics learned in high school, with opportunities to extend their understanding by applying it to a research experience. The experiment is in plasma physics, but a similar alliance can be implemented in any area of science. Although the number of high school students affected by any one alliance is small, the impact is potentially large in the scientific life of a participating student or teacher

Region-Specific Myelin Pathology in Mice Lacking the Golli Products of the Myelin Basic Protein Gene

The myelin basic protein (MBP) gene encodes two families of proteins, the classic MBP constituents of myelin and the golli-MBPs, the function of which is less well understood. In this study, targeted ablation of the golli-MBPs, but not the classic MBPs, resulted in a distinct phenotype unlike that of knock-outs (KOs) of the classic MBPs or other myelin proteins. Although the golli KO animals did not display an overt dysmyelinating phenotype, they did exhibit delayed and/or hypomyelination in selected areas of the brain, such as the visual cortex and the optic nerve, as determined by Northern and Western blots and immunohistochemical analysis with myelin protein markers. Hypomyelination in some areas, such as the visual cortex, persisted into adulthood. Ultrastructural analysis of the KOs confirmed both the delay and hypomyelination and revealed abnormalities in myelin structure and in some oligodendrocytes. Abnormal visual-evoked potentials indicated that the hypomyelination in the visual cortex had functional consequences in the golli KO brain. Evidence that the abnormal myelination in these animals was a consequence of intrinsic problems with the oligodendrocyte was indicated by an impaired ability of oligodendrocytes to form myelin sheets in culture and by the presence of abnormal Ca^(2+) transients in purified cortical oligodendrocytes studied in vitro. The Ca^(2+) results reported in this study complement previous results implicating golli proteins in modulating intracellular signaling in T-cells. Together, all these findings suggest a role for golli proteins in oligodendrocyte differentiation, migration, and/or myelin elaboration in the brain

Predicting Phenotypic Diversity and the Underlying Quantitative Molecular Transitions

During development, signaling networks control the formation of multicellular patterns. To what extent quantitative fluctuations in these complex networks may affect multicellular phenotype remains unclear. Here, we describe a computational approach to predict and analyze the phenotypic diversity that is accessible to a developmental signaling network. Applying this framework to vulval development in C. elegans, we demonstrate that quantitative changes in the regulatory network can render ~500 multicellular phenotypes. This phenotypic capacity is an order-of-magnitude below the theoretical upper limit for this system but yet is large enough to demonstrate that the system is not restricted to a select few outcomes. Using metrics to gauge the robustness of these phenotypes to parameter perturbations, we identify a select subset of novel phenotypes that are the most promising for experimental validation. In addition, our model calculations provide a layout of these phenotypes in network parameter space. Analyzing this landscape of multicellular phenotypes yielded two significant insights. First, we show that experimentally well-established mutant phenotypes may be rendered using non-canonical network perturbations. Second, we show that the predicted multicellular patterns include not only those observed in C. elegans, but also those occurring exclusively in other species of the Caenorhabditis genus. This result demonstrates that quantitative diversification of a common regulatory network is indeed demonstrably sufficient to generate the phenotypic differences observed across three major species within the Caenorhabditis genus. Using our computational framework, we systematically identify the quantitative changes that may have occurred in the regulatory network during the evolution of these species. Our model predictions show that significant phenotypic diversity may be sampled through quantitative variations in the regulatory network without overhauling the core network architecture. Furthermore, by comparing the predicted landscape of phenotypes to multicellular patterns that have been experimentally observed across multiple species, we systematically trace the quantitative regulatory changes that may have occurred during the evolution of the Caenorhabditis genus

Impurity generation during intense lower hybrid heating experiments on the Alcator C tokamak

and disposal, in whole or in part by or for the United States govern-ment is permitted. By acceptance of this article, the publisher and/or recipient ac-knowledges the U.S. Government's right to retain a non-exclusive, royalty-free license in and to any copyright covering this paper. Experiments are underway on the Alcator C Tokamak with over 1 MW of RF power injected into the plasma at a frequency of 4.6 GHz to study both heating and current drive effects. During these studies, impurity genera-tion from limiter structures has been observed. The RF induced impurity influx is a strongly nonlinear function of net injected power. For Prf < 500 kW, only small effects are seen. As Prf approaches 1 MW, however, sharp increases in impurity influxes and Zeff are observed. Three different lim-iter materials have been used during these studies: molybdenum, graphite, and silicon-carbide coated graphite. In each case, the materials of the limiter structure are seen to dominate the increased impurity influx. In a typical case, with Prf = 1.0 MW e = 1.3 x 1014 cm- 3, and the SiC coated limiters, Zeff is seen to increase from 1.5 before the RF pulse to about 4 during the heating. At the same time, central Te increases from 2000 eV to 3000 eV and central Ti from 1200 eV to 1800 eV. Similar effects are seen in both H2 and D2 working gas discharges. The contribution to impurity genera-tion of nonthermal electrons, which are produced by the RF, is under investi-gation. Changes in edge plasma temperature and density, as well as the possibility that the particle transport is affected by the RF, are also being examined. Results of the experiments with the three different limiter materials are compared, and contributions of impurity radiation to the overall power balance are estimated