Visualization of nano-plasmons in graphene

We study localized plasmons at the nanoscale (nano-plasmons) in graphene. The collective excitations of induced charge density modulations in graphene are drastically changed in the vicinity of a single impurity compared to graphene's bulk behavior. The dispersion of nano-plasmons depends on the number of electrons and the sign, strength and size of the impurity potential. Due to this rich parameter space the calculated dispersions are intrinsically multidimensional requiring an advanced visualization tool for their efficient analysis, which can be achieved with parallel rendering. To overcome the problem of analyzing thousands of very complex spatial patterns of nano-plasmonic modes, we take a combined visual and quantitative approach to investigate the excitations on the two-dimensional graphene lattice. Our visual and quantitative analysis shows that impurities trigger the formation of localized plasmonic excitations of various symmetries. We visually identify dipolar, quadrupolar and radial modes, and quantify the spatial distributions of induced charges.Comment: 14 pages, 9 figure

Analysing cognitive test data: Distributions and non-parametric random effects

An important assumption in many linear mixed models is that the conditional distribution of the response variable is normal. This assumption is violated when the models are fitted to an outcome variable that counts the number of correctly answered questions in a questionnaire. Examples include investigations of cognitive decline where models are fitted to Mini Mental State Examination scores, the most widely used test to measure global cognition. Mini Mental State Examination scores take integer values in the 0–30 range, and its distribution has strong ceiling and floor effects. This article explores alternative distributions for the outcome variable in mixed models fitted to mini mental state examination scores from a longitudinal study of ageing. Model fit improved when a beta-binomial distribution was chosen as the distribution for the response variable

Interference of functional dual-tasks on gait in untrained people with Parkinson's disease and healthy controls: a cross-sectional study

[EN] Background In Parkinson's disease (PD) population, performing secondary tasks while walking further deteriorates gait and restrict mobility in functional contexts of daily life. This study (1) analyzed the interference of functional cognitive and motor secondary task on untrained people with PD and (2) compared their walking with healthy subjects. Methods Forty people with PD (aged 66.72 [7.5] years, Hoehn and Yahr stage I-II-III, on-medication) composed the PD group (PDG) and 43 participants (aged 66.60 [8.75] years) formed the group of healthy counterparts (HG). Gait was evaluated through spatiotemporal, kinematic and kinetic outcomes in five conditions: single task (ST) and visual, verbal, auditory and motor dual-task (DT). Results The velocity, stride length, and braking force performance of both groups was statistically higher in the ST condition than in verbal, auditory and motor DT (p.05). Conclusions: In untrained participants with PD, verbal and motor secondary tasks affect gait significantly, while auditory and visual tasks interfere to a lesser extent. Untrained people with PD have a poorer gait performance than their healthy counterparts, but in different grades according to the analyzed variables. Trial registration The data in this paper are part of a single-blind, randomized, controlled trial and correspond to the evaluations performed before a physical rehabilitation program, retrospectively registered with the number at clinicaltrial.govNCT04038866.San Martín Valenzuela, C.; Dueñas Moscardó, L.; Lopez Pascual, J.; Serra-Añó, P.; Tomás, JM. (2020). Interference of functional dual-tasks on gait in untrained people with Parkinson's disease and healthy controls: a cross-sectional study. BMC Musculoskeletal Disorders. 21(1):1-11. https://doi.org/10.1186/s12891-020-03431-xS111211Jankovic J. Parkinson’s disease: clinical features and diagnosis. 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Psychologie et NeuroPsychiatrie du Vieillissement. 2006;4:215–25.Raffegeau TE, Krehbiel LM, Kang N, Thijs FJ, Altmann LJP, Cauraugh JH, et al. A meta-analysis: Parkinson’s disease and dual-task walking. Parkinsonism Relat Disord. 2019 May;62:28–35.Eric R. Kandel, James H. Schwartz, Thomas M. Jessell, Steven a. Siegelbaum, A. J. Hudspeth. Principles of neural science. Fifth edition. McGraw-Hill Medical: United States of America; 2013.Eisinger RS, Cernera S, Gittis A, Gunduz A, Okun MS. A review of basal ganglia circuits and physiology: application to deep brain stimulation. Parkinsonism Relat Disord. 2019 Feb;59:9–20.Isella V, Mapelli C, Morielli N, De Gaspari D, Siri C, Pezzoli G, et al. Validity and metric of MiniMental Parkinson and MiniMental state examination in Parkinson’s disease. Neurol Sci. 2013;34:1751–8.Morris ME, McGinley J, Huxham F, Collier J, Iansek R. Constraints on the kinetic, kinematic and spatiotemporal parameters of gait in Parkinson’s disease. Hum Mov Sci. 1999;18:461–83.Brauer SG, Morris ME. Can people with Parkinson’s disease improve dual tasking when walking? Gait & Posture. 2010;31:229–33.Baron EI, Miller Koop M, Streicher MC, Rosenfeldt AB, Alberts JL. Altered kinematics of arm swing in Parkinson’s disease patients indicates declines in gait under dual-task conditions. Parkinsonism Relat Disord. 2018;48:61–7.Rochester L, Galna B, Lord S, Burn D. The nature of dual-task interference during gait in incident Parkinson’s disease. Neuroscience. 2014;265:83–94.Logan D, Kiemel T, Dominici N, Cappellini G, Ivanenko Y, Lacquaniti F, et al. The many roles of vision during walking. Exp Brain Res. 2010;206:337–50.de Luna RA, Mihailovic A, Nguyen AM, Friedman DS, Gitlin LN, Ramulu PY. The Association of Glaucomatous Visual Field Loss and Balance. Transl Vis Sci Technol. 2017 May 22;6(3):8.Suarez H, Geisinger D, Ferreira ED, Nogueira S, Arocena S, Roman CS, et al. Balance in Parkinson’s disease patients changing the visual input. Brazilian Journal of Otorhinolaryngology. 2011;77:651–5.Wu T, Hallett M. Neural correlates of dual task performance in patients with Parkinson’s disease. J Neurol Neurosurg Psychiatry. 2008;79:760–6.Canning CG. The effect of directing attention during walking under dual-task conditions in Parkinson’s disease. Parkinsonism Relat Disord. 2005;11:95–9.Wu T, Liu J, Zhang H, Hallett M, Zheng Z, Chan P. Attention to automatic movements in Parkinson’s disease: modified automatic mode in the striatum. Cereb Cortex. 2015;25:3330–42.de Roiz R. M, Cacho EWA, Pazinatto MM, Reis JG, Cliquet a. Barasnevicius-Quagliato EMA Gait analysis comparing Parkinson’s disease with healthy elderly subjects Arq Neuropsiquiatr. 2010;68:81–6.Grabli D, Karachi C, Welter M-L, Lau B, Hirsch EC, Vidailhet M, et al. Normal and pathological gait: what we learn from Parkinson’s disease. J Neurol Neurosurg Psychiatry. 2012 Oct;83(10):979–85.Anna C, Serena F, Maurizio F. Del Sorbo Francesca, Romito Luigi M., Elia Antonio E., et al. quantitative gait analysis in parkin disease: possible role of dystonia. Mov Disord. 2016;31:1720–8.Morris M, Iansek R, McGinley J, Matyas T, Huxham F. Three-dimensional gait biomechanics in Parkinson’s disease: evidence for a centrally mediated amplitude regulation disorder. Mov Disord. 2005;20:40–50.Peterson CL, Kautz SA, Neptune RR. Braking and propulsive impulses increase with speed during accelerated and decelerated walking. Gait Posture. 2011;33:562–7.Chiu M-C, Wang M-J. The effect of gait speed and gender on perceived exertion, muscle activity, joint motion of lower extremity, ground reaction force and heart rate during normal walking. Gait & Posture. 2007;25:385–92.Muniz AMS, Liu H, Lyons KE, Pahwa R, Liu W, Nobre FF, et al. Comparison among probabilistic neural network, support vector machine and logistic regression for evaluating the effect of subthalamic stimulation in Parkinson disease on ground reaction force during gait. J Biomech. 2010;43:720–6.Chastan N, Do MC, Bonneville F, Torny F, Bloch F, Westby GWM, et al. Gait and balance disorders in Parkinson’s disease: impaired active braking of the fall of Centre of gravity. Mov Disord. 2009;24:188–95.Perneger T. What's wrong with Bonferroni adjustments. BMJ. 1998 Apr 18;316(7139):1236–8

Underlying Factors Associated with Anemia in Amazonian Children: A Population-Based, Cross-Sectional Study

Background: Although iron deficiency is considered to be the main cause of anemia in children worldwide, other contributors to childhood anemia remain little studied in developing countries. We estimated the relative contributions of different factors to anemia in a population-based, cross-sectional survey. Methodology: We obtained venous blood samples from 1111 children aged 6 months to 10 years living in the frontier town of Acrelandia, northwest Brazil, to estimate the prevalence of anemia and iron deficiency by measuring hemoglobin, erythrocyte indices, ferritin, soluble transferrin receptor, and C-reactive protein concentrations. Children were simultaneously screened for vitamin A, vitamin B-12, and folate deficiencies; intestinal parasite infections; glucose-6-phosphate dehydrogenase deficiency; and sickle cell trait carriage. Multiple Poisson regression and adjusted prevalence ratios (aPR) were used to describe associations between anemia and the independent variables. Principal Findings: The prevalence of anemia, iron deficiency, and iron-deficiency anemia were 13.6%, 45.4%, and 10.3%, respectively. Children whose families were in the highest income quartile, compared with the lowest, had a lower risk of anemia (aPR, 0.60; 95% CI, 0.37-0.98). Child age (<24 months, 2.90; 2.01-4.20) and maternal parity (>2 pregnancies, 2.01; 1.40-2.87) were positively associated with anemia. Other associated correlates were iron deficiency (2.1; 1.4-3.0), vitamin B-12 (1.4; 1.0-2.2), and folate (2.0; 1.3-3.1) deficiencies, and C-reactive protein concentrations (>5 mg/L, 1.5; 1.1-2.2). Conclusions: Addressing morbidities and multiple nutritional deficiencies in children and mothers and improving the purchasing power of poorer families are potentially important interventions to reduce the burden of anemia.Sao Paulo State Research Agency [FAPESP 07/53042-1]Sao Paulo State Research AgencyNational Research Agency of BrazilNational Research Agency of Brazil [CNPq 470573/2007-4

Measurement of the Forward-Backward Asymmetry in the B -> K(*) mu+ mu- Decay and First Observation of the Bs -> phi mu+ mu- Decay

We reconstruct the rare decays $B^+ \to K^+\mu^+\mu^-$, $B^0 \to K^{*}(892)^0\mu^+\mu^-$, and $B^0_s \to \phi(1020)\mu^+\mu^-$ in a data sample corresponding to $4.4 {\rm fb^{-1}}$ collected in $p\bar{p}$ collisions at $\sqrt{s}=1.96 {\rm TeV}$ by the CDF II detector at the Fermilab Tevatron Collider. Using $121 \pm 16$ $B^+ \to K^+\mu^+\mu^-$ and $101 \pm 12$ $B^0 \to K^{*0}\mu^+\mu^-$ decays we report the branching ratios. In addition, we report the measurement of the differential branching ratio and the muon forward-backward asymmetry in the $B^+$ and $B^0$ decay modes, and the $K^{*0}$ longitudinal polarization in the $B^0$ decay mode with respect to the squared dimuon mass. These are consistent with the theoretical prediction from the standard model, and most recent determinations from other experiments and of comparable accuracy. We also report the first observation of the $B^0_s \to \phi\mu^+\mu^- decay and measure its branching ratio${\mathcal{B}}(B^0_s \to \phi\mu^+\mu^-) = [1.44 \pm 0.33 \pm 0.46] \times 10^{-6}$using$27 \pm 6$signal events. This is currently the most rare$B^0_s$ decay observed.Comment: 7 pages, 2 figures, 3 tables. Submitted to Phys. Rev. Let