4,855 research outputs found
The SF-36: a simple, effective measure of mobility disability for epidemiological studies
No full textBackgroundMobility disability is a major problem in older people. Numerous scales exist for the measurement of disability but often these do not permit comparisons between study groups. The physical functioning (PF) domain of the established and widely used Short Form-36 (SF-36) questionnaire asks about limitations on ten mobility activities.ObjectivesTo describe prevalence of mobility disability in an elderly population, investigate the validity of the SF-36 PF score as a measure of mobility disability, and to establish age and sex specific norms for the PF score.MethodsWe explored relationships between the SF-36 PF score and objectively measured physical performance variables among 349 men and 280 women, 59-72 years of age, who participated in the Hertfordshire Cohort Study (HCS). Normative data were derived from the Health Survey for England (HSE) 1996.Results32% of men and 46% of women had at least some limitation in PF scale items. Poor SF-36 PF scores (lowest fifth of the gender-specific distribution) were related to: lower grip strength; longer timed-up-and-go, 3m walk, and chair rises test times in men and women; and lower quadriceps peak torque in women but not men. HSE normative data showed that median PF scores declined with increasing age in men and women.ConclusionOur results are consistent with the SF-36 PF score being a valid measure of mobility disability in epidemiological studies. This approach might be a first step towards enabling simple comparisons of prevalence of mobility disability between different studies of older people. The SF-36 PF score could usefully complement existing detailed schemes for classification of disability and it now requires validation against them
First-order system least squares for the Stokes and linear elasticity equations: Further results
No full textFirst-order system least squares (FOSLS) was developed in [SIAM J. Numer. Anal., 34 (1997), pp. 1727-1741; SIAM J. Numer. Anal., 35 (1998), pp. 320-335] for Stokes and elasticity equations. Several new results for these methods are obtained here. First, the inverse-norm FOSLS scheme that was introduced but not analyzed in [SIAM J. Numer. Anal., 34 ( 1997), pp. 1727-1741] is shown to be continuous and coercive in the L-2 norm. This result is shown to hold for pure displacement or pure traction boundary conditions in two or three dimensions, and for mixed boundary conditions in two dimensions. Next, the FOSLS schemes developed in [SIAM J. Numer. Anal., 35 (1998), pp. 320-335] are applied to the pure displacement problem in planar and spatial linear elasticity by eliminating the pressure variable in the FOSLS formulations of [SIAM J. Numer. Anal., 34 (1997), pp. 1727-1741]. The idea of two-dimensional variable rotation is then extended to three dimensions to make the intervariable coupling subdominant (uniformly so in the Poisson ratio for elasticity). This decoupling ensures optimal (uniform) performance of finite element discretization and multigrid solution methods. It also allows special treatment of the new trace variable, which corresponds to the divergence of velocity in the case of Stokes, so that conservation can be easily imposed, for example. Numerical results for various boundary value problems of planar linear elasticity are studied in a companion paper [SIAM J. Sci. Comput., 21 (2000), pp. 1706-1727].Z Cai: This author was sponsored by the National Science Foundation under grant DMS-9619792;
C.-O. Lee: This author was sponsored by BSRI-97-1436 and KOSEF 97-0701-01-01-3.
T. A. Manteuffel and S. F. McCormick: These
authors were sponsored by the National Science Foundation under grant DMS-9706866 and the Department of Energy under grant DE-FG03-93ER2516
SF Gospel: Blog contents, 2006-2015
No full textSF Gospel (2006-2015) was a blog exploring religious and theological themes in science fiction and popular culture by Gabriel Mckee, author of The Gospel According to Science Fiction. The primary PDF contains the textual content of the blog, along with most images that accompanied the original posts. The appendix PDF contains guest posts written by Mckee for other blogs and websites (including SF Signal, Holy Heroes, Nerve.com, and Religion Dispatches) during the course of SF Gospel's existence
Additional Files for Master Thesis "Framing Diets for Policy to Fight Climate Change"
No full textAdditional files for Master Thesis "Framing Diets for Policy to Fight Climate Change: Using video messages to measure the effect of goal framing on attitudes and intentions to reduce beef and dairy consumption to fight climate change"
Datasets
Intervention Framed Videos
Written within the M.Sc. Public Policy and Human Development at Maastricht University MGSoG/UNU-MERIT
Author: Sten Ritterfeld
Supervisor: Michelle González Amador
Submission date: July 12, 202
Phonological Neighborhood Density Affects Word Production: Corpus, computational and neurophysiological evidence
No full textPhonological neighbourhood density (PND): Words in our mental dictionaries that have many close “neighbours” (other words that sound similar) have High-PND (cat, mat, hat). Words with few neighbours have Low-PND (cow). By 2, most children understand and say High- and Low-PND words. But Late Talker’s (LT) understand, but do not say, words of Low-PND1.
Hypothesis: Low-PND words may place greater demands on cognitive processes than High-PND words during speech production.
Corpus evidence: Parent completed vocabulary checklists for 2-year-olds (English2 n=222, French3 n=200, Danish4 n=894). PND and frequency values for each child’s words came from corpus databases (CELEX, Lexique 3, Odese Twin Corpus).
Result: In regressions 41%-53% and 3%-14% of the variance in expressive vocabulary size was accounted for by PND and word frequency respectively. LTs had higher mean PND values than their TD peers.
Computational evidence: A Simple Recurrent Network (SRN) computer program was exposed to the meaning and phonological form of 268 monosyllabic English words that varied on PND, and the phonological form only of 2320 words. Input frequency to the SRN was controlled.
Result: The SRN (computer) learning pattern resembled that of children; smaller lexicons and first-learned words were of High-PND.
Neurophysiological evidence: 7-year olds (N=25) named 40 pictures of High- and Low-PND objects (cat, cow) while EEG data were collected. Results: Low-PND pictures had greater voltage amplitudes at the time of phonological encoding (N2-P3 ERP components) and were named slower than High-PND pictures. Greater neural effort was needed to put together the speech sounds that make up low PND words.
Conclusions: It is easier to say High-PND words than Low-PND words, presumably because of a neural spreading activation effect (neural networks firing together).
References 1.Stokes, S. F. (2014). The impact of phonological neighborhood density on typical and atypical emerging lexicons. Journal of Child Language, 41(3), 634-657. 2.Stokes, S. F. (2010). Neighborhood density and word frequency predict vocabulary size in toddlers. Journal of Speech, Language, and Hearing Research, 53, 670-683. 3.Stokes, S. F., Kern, S., & dos Santos, C. (2012). Extended statistical learning as an account for slow vocabulary growth. Journal of Child Language, 39, 105-129. 4.Stokes, S.F., Bleses, D., BasbÌüll, & Lambertsen, C. (2012). Statistical learning in emerging lexicons: The case of Danish. Journal of Speech, Language, and Hearing Research, 55, 1265-1273.
5.Takac, M., Knott, A., & Stokes, S. F. (2016). A simple recurrent network model of neighbourhood density effects in vocabulary development. Journal of Child Language. 6.Hansmann, D., Gavin, W. J. & Stokes, S. F. (2015). Influence of phonological neighbourhood density on word production in children: An ERP study. Paper presented at the ASHA convention, Denver Nov.
7.Dell, G. S. (1986). A spreading activation theory of retrieval in sentence production. Psychological Review, 93(3), 283-321
Development of a rotor model for the numerical simulation of helicopter exterior flow-fields
No full textIncludes bibliographical references (leaves 84-85).A numerical methodology is developed to model the effect of a rotor on the surrounding flow-field. The model calculates the time-averaged aerodynamic forces exerted on the air by the fan blades within the blade-swept region, and permits the user to specify blade properties such as cross-sectional profile and orientation at a particular radial and azimuthal location. The calculated forces are included as source terms within the Reynolds-averaged Navier-Stokes equations for an incompressible fluid, which are solved by the commercial CFD solver, FLUENT. The effects of turbulence are incorporated through the use of Launder and Spalding's k-g turbulence model. This method is selected as being the most efficient use of the resources available, giving the economic advantages of a steady simulation, while allowing radial and azimuthal variations of rotor characteristics. In order to validate the accuracy of the numerical model for both aligned and non-aligned inflow conditions, results are compared with experimental data reported for an axial flow fan. Agreement between experimental and numerical results is excellent to good. Fan static pressure rise is closely predicted by the numerical solution, while fan power consumption and fan static efficiency are under and over-predicted respectively. This error may be attributed to frictional losses not accounted for in the numerical model. These include physical rotational instabilities, leading to increased mechanical losses, and tip effects due to the clearance between the fan blade tips and the fan casing. Trends are nevertheless consistently predicted by the numerical model for inflow angles up to 45°, and for the range of blade pitch settings used. The adverse effect of off-axis inflow on the fan static pressure rise is numerically predicted, while fan power consumption is found to remain independent of inflow angle, as had been experimentally observed. The rotor model is finally integrated with the fuselage of the CIRSTEL (Combined Infra-Red Suppression and Tail rotor Elimination) prototype in an analysis of the helicopter exterior flow-field. No experimental data for this configuration was available for validation purposes. However, the model is used in the simulation of several common helicopter flight conditions. Results are presented graphically, and generally indicate good agreement with physically observed phenomena
Anterior thigh composition measured using ultrasound imaging to quantify relative thickness of muscle and non-contractile tissue: a potential biomarker for musculoskeletal health
No full textThis study aimed to use ultrasound imaging to provide objective data on the effects of ageing and gender on relative thickness of quadriceps muscle and non-contractile tissue thickness (subcutaneous fat, SF, combined with perimuscular fascia). In 136 healthy males and females (aged 18-90 years n=63 aged 18-35 years; n=73 aged 65-90). Images of the anterior thigh (dominant) were taken in relaxed supine using B-mode ultrasound imaging. Thickness of muscle, SF and perimuscular fascia were measured, and percentage thickness of total anterior thigh thickness calculated. Independent t-tests compared groups. Correlation between tissue thickness and BMI was examined using Pearson’s coefficient. Muscle thickness was: 39±8mm in young males, 29±6mm in females, 25±4mm in older males and 20±5mm in females. Percentage muscle to thigh thickness was greater in young participants (p=0.001). Percentage SF and fascia was 17±6% in young and 26±8% in older males, 32±7% in young and 44±7% in older females. BMI was similar for age and correlated moderately with non-contractile tissue (r=0.54; p<0.001) and poorly with muscle (r=-0.01; p=0.93). In conclusion, this novel application of ultrasound imaging as a simple and rapid means of assessing thigh composition (relative thickness of muscle and non-contractile tissue) may help inform health status, e.g. in older people at risk of frailty and loss of mobility, and aid monitoring effects of weight loss or gain, deconditioning and exercise
Ultrasound imaging for measuring muscle and subcutaneous fat tissue thickness of the anterior thigh: A two-year longitudinal study in middle age
No full textBackground Ultrasound (US) imaging technique is widely used in research and clinical settings to assess the morphology and morphometry of neuromusculoskeletal structures. The technique has reported validity and reliability in measuring the size of various muscles under controlled conditions. The aim of the present study was to assess anterior thigh thickness using US imaging, in a healthy cohort of middle-aged older adults.Methods Participants included seventeen healthy older adults involved in regular moderate-vigorous activities (age range 39-66 years). US imaging scans of the anterior thighs two years since baseline measurements were performed. Images were analyzed off-line to compare US imaging measurements of muscle thickness and subcutaneous fat (SF) of the anterior thigh taken at baseline and after two years.Results There was no significant difference between muscle thickness measurements taken at baseline and after two years (Mean, standard deviation; baseline=2.80±0.71cm; follow-up=2.77±0.72cm, p=0.33). There was also no significant change in SF thickness (baseline=1.04±0.41cm; follow-up=1.06±0.40, p=0.33).Conclusions The results show there was no decline in anterior thigh muscle thickness or increase in SF in the healthy cohort studied using US imaging over a two-year period. These findings demonstrate the robustness of US imaging measurements over time
Impact of moderate pump–Stokes chirp on femtosecond coherent anti‐Stokes Raman scattering spectra
No full textThe effects of inducing moderate chirp in the pump and Stokes beams in chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering (CARS) spectroscopy are discussed. This is an important issue for measurements in high-pressure systems where the CARS beams must be transmitted through glass of significant thickness to reach the probe volume of interest. The effects were investigated both experimentally, by inserting disks of SF-11 glass into the pump and Stokes beam paths, and theoretically, by incorporating pulse chirp into our time-dependent density matrix (TDDM) simulations. Experimentally, we found that inducing moderate pump and Stokes chirp produced significant spectral narrowing of the nonresonant four-wave mixing contribution to the CARS signal, and this allowed us to control the resonant excitation bandwidth to eliminate interferences from neighboring species. The temperature measurement accuracy and precision were essentially unchanged with respect to the unchirped pump and Stokes case. The effect of moderate pump and Stokes chirp on the narrowing of the Raman excitation efficiency envelope was investigated by solving the full set of TDDM through direct numerical integration. The numerical efficiency of the solutions was enhanced dramatically by developing a parallel version of the TDDM code. The calculated Raman excitation efficiency profile was incorporated in our phenomenological spectral fitting codes.The author would like to thank Dr. Carlo Scalo for his great help on the parallelization of the numerical code. Funding for this research program was provided by the U.S. Department of Energy, Division of Chemical Sciences, Geosciences and Biosciences (Grant DE-FG02-03ER15391); Basic Energy Sciences fundation (DE-FG02-03ER15391), and by the King Abdullah University of Science and Technology, CCF subaward (No. 1975-01)
Additional Files for Master Thesis "Framing Diets for Policy to Fight Climate Change"
No full textAdditional files for Master Thesis "Framing Diets for Policy to Fight Climate Change: Using video messages to measure the effect of goal framing on attitudes and intentions to reduce beef and dairy consumption to fight climate change"
Datasets
Intervention Framed Videos
Written within the M.Sc. Public Policy and Human Development at Maastricht University MGSoG/UNU-MERIT
Author: Sten Ritterfeld
Supervisor: Michelle González Amador
Submission date: July 12, 202
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