Validation of a sports nutrition knowledge questionnaire for athletes in the United Kingdom and Ireland.

Sound general and sports nutrition knowledge in athletes is essential for making appropriate dietary choices. Assessment of nutrition knowledge enables evaluation and tailoring of nutrition education. However, few well-validated tools are available to assess nutrition knowledge in athletes. The objective of the present study was to establish the validity of the Platform to Evaluate Athlete Knowledge Sports - Nutrition Questionnaire (PEAKS-NQ) for use in the United Kingdom and Irish (UK-I) athletes. To confirm content validity, twenty-three sports nutritionists (SNs) from elite, UK-I sports institutes provided feedback on the PEAKS-NQ via a modified Delphi method. After minor changes, the UK-I version of the PEAKS-NQ was administered to UK-I SN from the British Dietetic Association Sport and Exercise Nutrition Register, and elite athletes (EA) training at elite sports institutes in the UK and Ireland. Independent samples -test and independent samples median tests were used to compare PEAKS-NQ total and subsection scores between EA and SN (to assess construct validity). Cronbach's alpha (good ≥ 0⋅7) was used to establish internal consistency. The SN achieved greater overall [SN ( 23) 92⋅3 (9⋅3) EA ( 154): 71⋅4 (10⋅0)%; < 0⋅001] and individual section scores ( < 0⋅001) except Section B, Identification of Food Groups ( = 0⋅07). Largest knowledge differences between SN and EA were in Section D, Applied Sports Nutrition [SN: 88⋅5 (8⋅9) EA: 56⋅7 (14⋅5)%; < 0⋅00]. Overall ES was large (2⋅1), with subsections ranging from 0⋅6 to 2⋅3. Cronbach's alpha was good (0⋅83). The PEAKS-NQ had good content and construct validity, supporting its use to assess nutrition knowledge of UK-I athletes

Response of a CMS HGCAL silicon-pad electromagnetic calorimeter prototype to 20-300 GeV positrons

The Compact Muon Solenoid Collaboration is designing a new high-granularity endcap calorimeter, HGCAL, to be installed later this decade. As part of this development work, a prototype system was built, with an electromagnetic section consisting of 14 double-sided structures, providing 28 sampling layers. Each sampling layer has an hexagonal module, where a multipad large-area silicon sensor is glued between an electronics circuit board and a metal baseplate. The sensor pads of approximately 1 cm$^2$ are wire-bonded to the circuit board and are readout by custom integrated circuits. The prototype was extensively tested with beams at CERN's Super Proton Synchrotron in 2018. Based on the data collected with beams of positrons, with energies ranging from 20 to 300 GeV, measurements of the energy resolution and linearity, the position and angular resolutions, and the shower shapes are presented and compared to a detailed Geant4 simulation

Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20−-300 GeV/c

The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing medium and silicon sensors as an active medium in the regions of high radiation exposure, and scintillator tiles directly readout by silicon photomultipliers in the remaining regions. As part of the development of the detector and its readout electronic components, a section of a silicon-based HGCAL prototype detector along with a section of the CALICE AHCAL prototype was exposed to muons, electrons and charged pions in beam test experiments at the H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology as foreseen for the HGCAL but with much finer longitudinal segmentation. The performance of the calorimeters in terms of energy response and resolution, longitudinal and transverse shower profiles is studied using negatively charged pions, and is compared to GEANT4 predictions. This is the first report summarizing results of hadronic showers measured by the HGCAL prototype using beam test data.Comment: To be submitted to JINS

Model selection in a stochastic setting.

The given data is a set of observations on functionals of a trajectory of a system of differential equations. The a priori information is that the system is a member of a parametric family of systems of increasing complexity. The problem is to use the data to identify the particular member of this family which generated the observed data. The method associates each candidate model with the analogue of a generalised smoothing spline fitted to the given data. The resulting values of the smoothing parameter as well as graphical inspection of fit provide a basis for model selection

The Use of diagnostics in web-based learning for introductory statistics courses

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Applications of L1 regularisation

The lasso algorithm for variable selection in linear models, introduced by Tibshirani, works by imposing an $l_1$~norm bound constraint on the variables in a least squares model and then tuning the model estimation calculation using this bound. This introduction of the bound is interpreted as a form of regularisation step. It leads to a form of quadratic program which is solved by a straight-forward modification of a standard active set algorithm for each value of this bound. Considerable interest was generated by the discovery that the complete solution trajectory parametrised by this bound is piecewise linear and can be calculated very efficiently. Essentially it takes no more work than the solution of either the unconstrained least squares problem or the quadratic program at a single bound value. This has resulted in the study both of the selection problem for different objective and constraint choices and of applications to such areas as data compression and the generation of sparse solutions of very under-determined systems. One important class of generalisation is to quantile regression estimation problems. The original continuation idea extends to these polyhedral objectives in an interesting two phase procedure which involves both the constrained and Lagrangian forms of the problem at each step. However, it is significantly less computationally effective than is the original algorithm for least squares objectives. In contrast, the piecewise linear estimation problem can be solved for each value of the $l_1$~bound by a relatively efficient simplicial descent algorithm, and that this can be used to explore trajectory information in a manner which is at least competitive with the homotopy algorithm in this context. The form of line search used in the descent steps has an important bearing on the effectiveness of the algorithm. A comparison is given between the relative performance of the simplicial descent algorithm used and an interior point method on the piecewise linear estimation problem. References I. Barrodale and F. D. K. Roberts. An improved algorithm for $l_1$ linear approximation. SIAM J. Numer. Anal., 10:839--848, 1973. P. Bloomfield and W. L. Steiger. Least Absolute Deviations. Birkhauser, Boston, 1983. H. D. Bondell and B. J. Reich. Simultaneous regression shrinkage, variable selection, and supervising clustering of predictors with {OSCAR}. Biometrics, 64:115--123, 2008. doi:10.1111/j.1541-0420.2007.00843.x E. Candes and T. Tao. The Dantzig selector: statistical estimation when $p$ is much larger than $n$. Ann. Statist., 35(6):2313--2351, 2007. doi:10.1214/009053606000001523 D. L. Donoho and Y. Tsaig. Fast solution of $l_1$-norm minimization problems when the solution may be sparse. IEEE Trans. Inf. Theory, 54:4789--4812, 2008. doi:10.1109/TIT.2008.929958 R. Koenker. Quantile Regression. Cambridge University Press, 2005. Y. Li and J. Zhu. {$L_1$}-norm quantile regression. J. Comp. Graph. Stat., 17(1):163--185, 2008. doi:10.1198/106186008X289155 M. R. Osborne. Simplicial algorithms for minimizing polyhedral functions. Cambridge University Press, 2001. M. R. Osborne, Brett Presnell, and B. A. Turlach. On the Lasso and its dual. J. Comp. Graph. Stat., 9(2):319--337, 2000. http://www.jstor.org/stable/1390657 M. R. Osborne and B. A. Turlach. A homotopy algorithm for the quantile regression lasso and related piecewise linear problems. J. Comp. Graph. Stat., 2010. Accepted for publication. doi:10.1198/jcgs.2011.09184 S. Portnoy and R. Koenker. The Gaussian hare and the Laplacian tortoise: computability of squared error vs absolute error estimates. Stat. Sci., 12:279--300, 1997. http://www.jstor.org/stable/2246216 S. Rosset and Ji Zhu. Piecewise linear regularised solution paths. Ann. Stat., 35(3):1012--1030, 2007. doi:10.1214/009053606000001370 R. Tibshirani. Regression shrinkage and selection via the lasso. J. R. Stat. Soc., Ser. B, 58(1):267--288, 1996. http://www.jstor.org/stable/2346178 B. A. Turlach, W. N. Venables, and S. J. Wright. Simultaneous variable selection. Technometrics, 47(3):349--363, 2005. doi:10.1198/004017005000000139 Y. Yao and Y. Lee. Another look at linear programming for feature selection via methods of regularization. Technical Report 800, Department of Statistics, Ohio State University, 2007. M. Yuan and H. Zou. Efficient global approximation of generalised nonlinear {$\ell _1$} regularised solution paths and its applications. J. Am. Stat. Assoc., 104:1562--1573, 2009. doi:10.1198/jasa.2009.tm08287 J. Zhu, T. Hastie, S. Rosset, and R. Tibshirani. $l_1$-norm support vector machines. Adv. Neural Inf. Process. Syst., 16:49--56, 2004. http://books.nips.cc/papers/files/nips16/NIPS2003_AA07.pdf H. Zou and T. Hastie. Regularization and variable selection via the elastic net. J. R. Stat. Soc., Ser. B, 67:301--320, 2005. http://www.jstor.org/stable/3647580 H. Zou and M. Yuan. Regularised simultaneous model selection in multiple quantiles regression. Comp. Stat. Data Anal., 52:5296--5304, 2008. doi:10.1016/j.csda.2008.05.01

Thin film models in a stochastic setting

Dunn and Tichenor (1988) proposed a class of differential equation models to describe the phenomenon of transient sink behaviour for organic emissions exhibited by interior surface films in state-of-the-art emission test chambers. Data from a particular application is used to exemplify the use of a model selection scheme which embeds the derived models within a class of stochastic differential equations. These embeddings have the property that the quality of model fit varies inversely with the strength of the stochastic forcing term. Results of this modelling application are discussed

Psychometric properties of two measures of childhood internalizing problems in a Bangladeshi sample

Objectives: In order to assist mental health services in developing countries, a key issue is the availability of psychometrically sound, brief, and cost-effective measures that have been tested within the relevant context. The present study was designed to evaluate within a young Bangladeshi population, the psychometric properties of two widely used Western measures of internalizing distress in young people: the short form of the Spence Children's Anxiety Scale and the Short Moods and Feelings Questionnaire. Method: The sample included 1,360 children and adolescents aged 9-17 years (M = 12.3 years, SD = 2.12) recruited from six districts of Bangladesh, including both community and emotionally at-risk participants. A total of 179 children were re-tested on the measures within 3-4 weeks. Results: Confirmatory factor analyses showed single-factor structures for both scales in the total sample and in both community and at-risk participants separately. Multiple group analyses across gender and age-group within the at-risk and community samples showed that the single-factor structure was suitable regardless of subgroup. Analyses also indicated acceptable internal consistency, test-retest reliability and construct validity for both scales. Conclusion: The two measures show promise as brief, reliable, and valid instruments for the assessment of internalizing distress among young people from Bangla-speaking communities. Practitioner points Positive clinical implications These two measures of internalizing distress in young people showed solid psychometric properties within samples collected from various parts of Bangladesh. The measures can therefore be used to assess anxiety and depression in Bangla-speaking youth. These measures should be of value in both clinical settings and at a community level to assess the need for services. Cautions and limitations Resource limitations did not allow comparison against diagnostic criteria and therefore cut-off scores to indicate clinical status among Bangladeshi youth will require further research.19 page(s