Validating Accelerometry and Skinfold Measures in Youth with Down Syndrome.

Current methods for measuring quantity and intensity of physical activity based on accelerometer output have been studied and validated in youth. These methods have been applied to youth with Down syndrome (DS) with no empirical research done to validate these measures. Similarly, individuals with DS have unique body proportions not represented by current methods used to estimate body composition. The purpose of this dissertation was (a) to examine the physical activity patterns in a large sample of youth with DS, (b) to examine the validity of the Actical accelerometer for measuring physical activity and (c) to investigate the accuracy of three published skinfold and anthropometric equations (Lohman, 1987; Slaughter et al., 1988; Kelly & Rimmer, 1987) used to estimate body composition in a sample of youth with DS. A total of 53 participants (27 with DS [15 males], 26 without DS [17 males]), between the ages of 8 and18 years were included in the present study. The Actical accelerometer was validated using a graded treadmill protocol. During the protocol participants wore a portable metabolic system. Heart rate, expired gases, and data counts from the Actical were collected, analyzed, and compared against current thresholds used for determining physical activity intensity. Anthropometric and skinfold measures were compared to results from a criterion measure (Bod Pod ®). Results of this study indicate (a) youth with DS engage in disproportional amounts of sedentary activity and spend very little time in moderate-to-vigorous activity, (b) the Actical ® accelerometer is a valid device for objectively measuring physical activity. However, current cut-points associated with physical activity intensities are likely to underestimate physical activity in youth with DS, and (c) Kelly and Rimmer’s (1987) anthropometric equation demonstrated the most accuracy when compared to the criterion measure. When measuring physical activity and body composition in this sample of youth with DS, considering the unique characteristics of individuals with DS improved measurement accuracy. Based on these results, future research should be directed toward developing population specific methods of measuring and interpreting physical activity and body composition data in a practical way.Ph.D.KinesiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/91414/1/philespo_1.pd

Concurrent Validity of the Sahara Portable Bone Sonometer

Osteoporosis is a contemporary health issue in today’s society. Bone mineral density tests have the ability to detect low bone density before a fracture occurs. Presently, dual-energy X-ray absorptiometry (DXA) is a common method used to measure bone mineral density. In recent years, quantitative ultrasonography (ultrasound) has been used as a screening device at health fairs and other venues to estimate bone mineral density. The use of ultrasound offers several advantages: it exposes individuals to no radiation, it is inexpensive, and requires less tester skill and oversight than DXA. PURPOSE: To assess the accuracy of calcaneal ultrasound as a bone mineral density screening method compared to total body dual-energy X-ray absorptiometry. METHODS: A total of 44 men between the ages of 18-25 years (21.6 ± 1.41) completed both a total body dual-energy X-ray absorptiometry (DXA) (GE Lunar) scan and an ultrasound (Hologic Sahara) calcaneus scan in a single visit. Correlation coefficients were calculated to determine the relationship between the two devices. Independent sample t-tests were used to determine if the two devices produced significantly different raw values. Bland-Altman plots were used to visually display agreement between devices. RESULTS: The ultrasound device had a weak relationship to the DXA (r = 0.514, p \u3c 0.01). Comparing the absolute agreement between the two devices, the ultrasound device was consistently conservative. It provided mean values of 0.689g/cm2 less than the DXA. It produced values significantly lower (1.31± 0.13 g/cm2 vs. 0.62 ± 0.14 g/cm2 , p \u3c 0.01). CONCLUSIONS: In this study, the ultrasound device produced values significantly lower than the values produced by the DXA. Ultrasound should not be used for individuals requiring a high degree of precision in their measurement. It could be useful, however, as a field device in the screening and estimating of bone mineral density

Acute and Chronic Effects of 12 Weeks of Combined Exercise Training on Plasma IL-6 in Post-Menopausal Women

Post-menopausal women exhibit higher levels of IL-6, a pro-inflammatory cytokine and anti-inflammatory myokine, and up-regulation of cellular receptors and cofactors for IL-6. Exercise is associated with an acute elevation of IL-6, but consistent exercise training diminishes this response. PURPOSE: to analyze the acute and chronic effects of 12 weeks of combined resistance and aerobic exercise training on plasma IL-6 in overweight or obese, post-menopausal women (55-75 years). METHODS: Forty-three women were randomly assigned to an exercise (EX, n=22) or an education (ED, n=21) group. EX completed resistance training (2 sets of 8 resistance exercises at 80% of 1RM) followed by aerobic training (25-minute treadmill walk at 70-80% of HRR) three times per week for 12 weeks. ED attended classes and activities two times per week for 12 weeks to control for seasonal variation and social interaction. Blood samples were collected a total of 8 times: 4 times before training (BT) (before the acute exercise bout (PRE), immediately after exercise (PO), 1 hour after exercise (1HR), and 2 hours after exercise (2HR)) and 4 times after training (AT). Lean, post-menopausal, and age-matched women were recruited for collection of one resting blood sample to serve as healthy controls (LN, n=11). Plasma IL-6 was determined using an ELISA kit according to manufacturer instructions. RESULTS: Baseline IL-6 concentration was significantly lower in the LN group compared to the EX (LN BT PRE: 1.0 ± 0.5; EX BT PRE: 2.8 ± 1.3 pg/mL; p\u3c0.001) and ED (LN BT PRE: 1.0 ± 0.5; ED BT PRE: 3.8 ± 1.7 pg/mL; p\u3c0.001) groups. No statistically significant BT/AT x group interaction was observed (p\u3e0.05) when the BT and AT PRE time points of the EX and ED groups were compared. In the EX group, PO was significantly higher than PRE (PRE 2.6 ± 1.2; PO 4.3 ± 1.8 pg/mL; p\u3c0.001), and PO was significantly higher than 1 HR (PO 4.3 ± 1.8; 1HR 3.4 ± 1.2 pg/mL; p=0.038) and 2HR (PO 4.3 ± 1.8; 2 HR 3.9 ± 1.6 pg/mL; p=0.005). No statistically significant differences were observed when corresponding time points before and after the intervention within a group were compared (i.e., EX BT PRE to EX AT PRE) (p\u3e0.05). CONCLUSION:The training intervention may not have been long enough and/or intense enough to observe a chronic effect of combined exercise training on plasma IL-6. Significant elevation of IL-6 immediately post-exercise was observed in the EX group, but this response was not blunted by consistent exercise training

Speckle statistics in adaptive optics images at visible wavelengths

Residual speckles in adaptive optics (AO) images represent a well-known limitation on the achievement of the contrast needed for faint source detection. Speckles in AO imagery can be the result of either residual atmospheric aberrations, not corrected by the AO, or slowly evolving aberrations induced by the optical system. We take advantage of the high temporal cadence (1 ms) of the data acquired by the System for Coronagraphy with High-order Adaptive Optics from R to K bands-VIS forerunner experiment at the Large Binocular Telescope to characterize the AO residual speckles at visible wavelengths. An accurate knowledge of the speckle pattern and its dynamics is of paramount importance for the application of methods aimed at their mitigation. By means of both an automatic identification software and information theory, we study the main statistical properties of AO residuals and their dynamics. We therefore provide a speckle characterization that can be incorporated into numerical simulations to increase their realism and to optimize the performances of both real-time and postprocessing techniques aimed at the reduction of the speckle noise

Magellan Adaptive Optics first-light observations of the exoplanet beta Pic b. II. 3-5 micron direct imaging with MagAO+Clio, and the empirical bolometric luminosity of a self-luminous giant planet

Young giant exoplanets are a unique laboratory for understanding cool, low-gravity atmospheres. A quintessential example is the massive extrasolar planet $\beta$ Pic b, which is 9 AU from and embedded in the debris disk of the young nearby A6V star $\beta$ Pictoris. We observed the system with first light of the Magellan Adaptive Optics (MagAO) system. In Paper I we presented the first CCD detection of this planet with MagAO+VisAO. Here we present four MagAO+Clio images of $\beta$ Pic b at 3.1 $\mu$m, 3.3 $\mu$m, $L^\prime$, and $M^\prime$, including the first observation in the fundamental CH$_4$ band. To remove systematic errors from the spectral energy distribution (SED), we re-calibrate the literature photometry and combine it with our own data, for a total of 22 independent measurements at 16 passbands from 0.99--4.8 $\mu$m. Atmosphere models demonstrate the planet is cloudy but are degenerate in effective temperature and radius. The measured SED now covers $>$80\% of the planet's energy, so we approach the bolometric luminosity empirically. We calculate the luminosity by extending the measured SED with a blackbody and integrating to find log($L_{bol}$/$L_{Sun}$) $= -3.78\pm0.03$. From our bolometric luminosity and an age of 23$\pm$3 Myr, hot-start evolutionary tracks give a mass of 12.7$\pm$0.3 $M_{Jup}$, radius of 1.45$\pm$0.02 $R_{Jup}$, and $T_{eff}$ of 1708$\pm$23 K (model-dependent errors not included). Our empirically-determined luminosity is in agreement with values from atmospheric models (typically $-3.8$ dex), but brighter than values from the field-dwarf bolometric correction (typically $-3.9$ dex), illustrating the limitations in comparing young exoplanets to old brown dwarfs.Comment: Accepted to ApJ. 27 pages, 22 figures, 19 table

Into the Blue: AO Science with MagAO in the Visible

We review astronomical results in the visible ({\lambda}<1{\mu}m) with adaptive optics. Other than a brief period in the early 1990s, there has been little astronomical science done in the visible with AO until recently. The most productive visible AO system to date is our 6.5m Magellan telescope AO system (MagAO). MagAO is an advanced Adaptive Secondary system at the Magellan 6.5m in Chile. This secondary has 585 actuators with < 1 msec response times (0.7 ms typically). We use a pyramid wavefront sensor. The relatively small actuator pitch (~23 cm/subap) allows moderate Strehls to be obtained in the visible (0.63-1.05 microns). We use a CCD AO science camera called "VisAO". On-sky long exposures (60s) achieve <30mas resolutions, 30% Strehls at 0.62 microns (r') with the VisAO camera in 0.5" seeing with bright R < 8 mag stars. These relatively high visible wavelength Strehls are made possible by our powerful combination of a next generation ASM and a Pyramid WFS with 378 controlled modes and 1000 Hz loop frequency. We'll review the key steps to having good performance in the visible and review the exciting new AO visible science opportunities and refereed publications in both broad-band (r,i,z,Y) and at Halpha for exoplanets, protoplanetary disks, young stars, and emission line jets. These examples highlight the power of visible AO to probe circumstellar regions/spatial resolutions that would otherwise require much larger diameter telescopes with classical infrared AO cameras.Comment: 14 pages, 8 figures, to appear in Proc. SPIE 914

Assembly, apparatus, system and method (PRaVDA range telescope)

Some embodiments of the present invention provide apparatus for detecting particles of radiation comprising: a plurality of solid state semiconductor detector devices provided at spaced apart locations along a beam axis, the detector devices each being configured to generate an electrical signal indicative of passage of a particle through or absorption of a particle by the device; and at least one absorber portion configured to absorb at least a portion of an energy of a particle, wherein one said at least one absorber portion is provided in a particle path between at least one pair of adjacent detector devices, the apparatus being configured to provide an output signal indicative of the energy of a particle, the output signal provided being dependent on the electrical signals indicative of passage of a particle through or absorption of a particle by the devices

Assembly, apparatus, system and method (PRaVDA strip detector)

Some embodiments of the present invention provide a 2D position-sensitive detector assembly comprising at least three substantially planar detector portions arranged in overlapping relationship as viewed normal to a plane of the detector portions, each detector portion comprising an array of substantially parallel, linear detector elements, the detector elements of respective detector portions being mutually non-parallel, the detector elements each being configured to generate one or more electrical signals in response to interaction of a particle of radiation therewith

PRaVDA: The First Solid-State System for Proton Computed Tomography

Proton CT is widely recognised as a beneficial alternative to con- ventional X-ray CT for treatment planning in proton beam radiotherapy. A novel proton CT imaging system, based entirely on solid-state detec- tor technology, is presented. Compared to conventional scintillator-based calorimeters, positional sensitive detectors allow for multiple protons to be tracked per read out cycle, leading to a potential reduction in proton CT scan time. Design and characterisation of its components are discussed. An early proton CT image obtained with a fully solid-state imaging sys- tem is shown and accuracy (as defined in Section IV) in Relative Stopping Power to water (RSP) quantified. A solid-state imaging system for proton CT, based on silicon strip detectors, has been developed by the PRaVDA collaboration. The sys- tem comprises a tracking system that infers individual proton trajecto- ries through an imaging phantom, and a Range Telescope (RT) which records the corresponding residual energy (range) for each proton. A back-projection-then-filtering algorithm is used for CT reconstruction of an experimentally acquired proton CT scan. An initial experimental result for proton CT imaging with a fully solid-state system is shown for an imaging phantom, namely a 75 mm diameter PMMA sphere containing tissue substitute inserts,imaged with a passively-scattered 125 MeV beam. Accuracy in RSP is measured to be ≤1.6% for all the inserts shown. A fully solid-state imaging system for proton CT has been shown capable of imaging a phantom with protons and successfully improving RSP accuracy. These promising results, together with system the capabil- ity to cope with high proton fluences (2×108 protons/s), suggests that this research platform could improve current standards in treatment planning for proton beam radiotherapy