Flowing sand - a possible physical realization of Directed Percolation

A simple model for flowing sand on an inclined plane is introduced. The model is related to recent experiments by Douady and Daerr [Nature 399, 241 (1999)] and reproduces some of the experimentally observed features. Avalanches of intermediate size appear to be compact, placing the critical behavior of the model into the universality class of compact directed percolation. On very large scales, however, the avalanches break up into several branches leading to a crossover from compact to ordinary directed percolation. Thus, systems of flowing granular matter on an inclined plane could serve as a first physical realization of directed percolation.Comment: 9 pages, 12 eps figure

Percent in a Nutshell …

Ironically, the “learning of percent” is one of the most problematic aspects of school mathematics. In our view, these difficulties are not associated with the arithmetic aspects of the “percent problems”, but mostly with two methodological issues: firstly, providing students with a simple and accurate understanding of the rationale behind the use of percent, and secondly - overcoming the psychological complexities of the fluent and comprehensive understanding by the students of the sometimes specific wordings of “percent problems”. Before we talk about percent, it is necessary to acquaint students with a much more fundamental and important (regrettably, not covered by the school syllabus) classical concepts of quantitative and qualitative comparison of values, to give students the opportunity to learn the relevant standard terminology and become accustomed to conventional turns of speech. Further, it makes sense to briefly touch on the issue (important in its own right) of different representations of numbers. Percent is just one of the technical, but common forms of data representation: p% = p × % = p × 0.01 = p × 1/100 = p/100 = p × 10-2 "Percent problems” are involved in just two cases: I. The ratio of a variation m to the standard M II. The relative deviation of a variation m from the standard M The hardest and most essential in each specific "percent problem” is not the routine arithmetic actions involved, but the ability to figure out, to clearly understand which of the variables involved in the problem instructions is the standard and which is the variation. And in the first place, this is what teachers need to patiently and persistently teach their students. As a matter of fact, most primary school pupils are not yet quite ready for the lexical specificity of “percent problems”. ....Math teachers should closely, hand in hand with their students, carry out a linguistic analysis of the wording of each problem ... Schoolchildren must firmly understand that a comparison of objects is only meaningful when we speak about properties which can be objectively expressed in terms of actual numerical characteristics. In our opinion, an adequate acquisition of the teaching unit on percent cannot be achieved in primary school due to objective psychological specificities related to this age and because of the level of general training of students. Yet, if we want to make this topic truly accessible and practically useful, it should be taught in high school. A final question to the reader (quickly, please): What is greater: % of e or e% of P

CAD systems as a method of research of mechanical properties metal roof support

В работе представлена методика анализа металлических арочных крепей, позволяющая исследовать компьютерную трехмерную модель крепи при различных видах и величинах нагрузок.The paper presents a methodology for the analysis of metal roof support that allows with use of computer explore the three-dimensional model to be fixed for different types and magnitudes of loads

On Diurnal and Annual Variations of Directional Detection Rates of Dark Matter

Direction sensitive direct detection of Weakly Interacting Massive Particles (WIMPs) as dark matter would provide an unambiguous non-gravitational signature of dark matter (DM). The diurnal variation of DM signal due to earth's rotation around its own axis can be a significant signature for galactic WIMPs. Because of particular orientation of earth's axis of rotation with respect to WIMP wind direction, the apparent direction of WIMP wind as observed at a detector can alter widely over a day. In this work we calculate the directional detection rates with their daily and yearly modulations in earth-bound dark matter experiments considering detailed features of the geometry and dynamics of the earth-sun system along with the solar motion in galactic frame. A separate halo model namely the dark disc model other than the usual standard halo model for dark matter halo is also considered and the results for two models are compared. We demonstrate the results for two types of gas detectors namely DRIFT (target material CS2) and NEWAGE (target material CF4) that use Time Projection Chamber techniques for measuring directionality of the recoil nucleus. The WIMP mass and recoil energy dependence of the daily variation of event rates are computed for specific detector and the sensitive ranges of mass and recoil energies for the considered detector are probed.Comment: 11 pages, 17 figure

Linguistic validation of cystic fibrosis quality of life questionnaires

OBJECTIVE: The purpose of this study was to validate the Portuguese translations of four cystic fibrosis quality of life questionnaires (CFQ). The first three were developed for patients with cystic fibrosis aged from 6 to 11 years, from 12 to 13 years and 14 years or more, while the fourth was developed for the parents of patients aged 6 to 13 years. MATERIAL AND METHODS: The four CFQ translations contained from 35 to 50 questions covering nine domains and were validated as follows: translation from English to Portuguese, pilot application, back translation and then approval by the author of the English versions. The four translations were applied to 90 stable patients (30 from each age group) and the parents of patients aged 6-13 years (n = 60), on two occasions with a 13 to 17 day interval. Intraclass Correlation Coefficients (ICC) were used to measure reproducibility. This study was approved by the Commission for Ethics in Research at the institution. RESULTS:Reproducibility was good (ICC = 0.62 to 0.99) for the four translations in all domains, with the exceptions of the Digestion domain for the 6 to 11 and 12 to 13 years age groups with ICC = 0.59 and 0.47, respectively and the Social Role domain for the 14 and over age group (ICC = -0.19 ) CONCLUSION: The translation and cultural adaptation for Brazil resulted in four CFQ versions that are easy to understand and offer good reproducibility.OBJETIVO: O propósito deste estudo foi validar em português as quatro versões de questionários de qualidade de vida em fibrose cística, desenvolvidos para pacientes com fibrose cística de 6 a 11 anos, de 12 a 13 e mais de 14 anos, e para os pais de pacientes de 6 a 13 anos. MATERIAL E MÉTODOS: A validação das quatro versões de questionários de qualidade de vida em fibrose cística (de 35 e 50 questões, abrangendo nove domínios) constou de: versão inglês-português, aplicação-piloto, tradução retrógrada e aprovação da autora da versão inglesa. As quatro versões foram aplicadas a 90 pacientes estáveis (30 de cada grupo etário) e aos pais de doentes de 6-13 anos (n = 60), em duas entrevistas, com intervalo de 13-17 dias. Foi avaliada a reprodutibilidade pelo coeficiente de correlação intraclasse (CCI). O estudo foi aprovado pela comissão de ética em pesquisa da instituição. RESULTADOS: A reprodutibilidade foi boa (CCI = 0,62 a 0,99) para as quatro versões, em todos os domínios, exceto o digestivo (CCI = 0,59 e CCI = 0,47) para os grupos etários de 6 a 11 e 12 a 13 anos, respectivamente, e domínio papel social (CCI = -0,19 ) para o grupo acima de 14 anos. CONCLUSÃO: A tradução e a adaptação à língua e à cultura brasileiras das quatro versões de questionários de qualidade de vida em fibrose cística mostraram-se de fácil entendimento e boa reprodutibilidade.Universidade de São Paulo Faculdade de Medicina Departamento de PediatriaUniversidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaFaculdade de Medicina do ABCUNIFESP-EPM Centro de Reabilitação PulmonarUniversidade de São Paulo Faculdade de Medicina Hospital das ClínicasUniversity of Miami Department of PsychologyUNIFESP, EPM, Centro de Reabilitação PulmonarSciEL

Uptake of Radium during barite recrystallization

In recent safety assessments for the direct disposal of spent nuclear fuel, Ra has been identified as a main contributor to dose after 100,000 years [1]. Due to the likely presence of BaSO4 which is formed by a reaction of Ba present as a fission product and sulfate ubiquitous in ground waters, it is expected that Ra will form a RaxBa1-xSO4 solid solution via recrystallization, which would lower the Ra concentration in solution significantly. However, due to a lack of reliable data, this solid solution system is currently not considered in long term safety assessments for nuclear waste repositories. For instance, the solubility of the pure RaSO4 endmember is not well defined. Furthermore, available literature data for the interaction parameter a0, which describes the non-ideality of the solid solution, vary by about one order of magnitude [2, 3]. The final Ra concentration in solution in this system is extremely sensitive to the amount of barite present, the difference in the solubility products of the end-member phases, and the degree of non-ideality of the solid solution phase. The EU-funded SKIN project investigates slow processes in close-to-equilibrium conditions for radionuclides in water/solid systems of relevance to nuclear waste management. Within the SKIN project we have combined a macroscopic experimental approach with ToF-SIMS and thermodynamic modelling to study in detail how a Ra containing solution will equilibrate with solid BaSO4 under repository relevant conditions. Batch experiments at close to equilibrium conditions show a final Ra concentration which is several orders of magnitude lower than the solubility of pure RaSO4. For the first time, the spatial distribution of Ra and Ba within the recrystallized barite powders - analysed using an ION-TOF TOF-SIMS - confirms the uptake of Ra into the solid. Solid-solution aqueous-solution equilibrium calculations were carried out for the BaSO4 – RaSO4 – H2O system with the GEMS – PSI code [4] in combination with the NAGRA – PSI thermodynamic database [10]. Thermodynamic modelling fits the experimental data best with an interaction parameter a0 = 0.6 and a solubility product KRaSO4 = -10.41.[1] Norrby, S.; Andersson, J.; Dverstorp, B.; Kautsky, F.; Lilja, C.; Sjöblom, R.; Sundström, B.; Toverud, Ö. & Wingefors, S. SKB 1997[2] Zhu, C. Geochimica et Cosmochimica Acta, 2004, 68, 3327-3337[3] Curti, E.; Fujiwara, K.; Iijima, K.; Tits, J.; Cuesta, C.; Kitamura, A.; Glaus, M. & Müller, W. Geochimica et Cosmochimica Acta, 2010, 74, 3553-3570[4] Wagner, T.; Kulik, D.; Hingerl, F. & Dmytrieva, S. Canadian Mineralogist, 2012, 50, 701 - 723[5] Hummel, W.; Berner, U.; Curti, E.; Pearson, F. J. & Thoenen, T.; Nagra technical report 02-16 200

The analysis of manufacturing techniques of tubular products made of steel 20X17H2 by hydraulic forging on smooth work holder

В даній роботі чисельним моделюванням методом кінцевих елементів проведено аналіз, гідропресування на гладкій оправці, показана можливість одержання заготовок для ствола пістолет-кулемета із сталі 20Х17Н2. Моделювання процесу виконувалось в програмному пакеті DEFORM, як вісесиметрична задача. Визначено можливість реалізації процесу, необхідний гідростатичний тиск, який прикладається на вільну поверхню заготовки при гідропресуванні та розподіл ступеня використання пластичності. Отримано кінцеву геометричну форму заготовки, що деформується та параметри напружено-деформованого стану, визначено зусилля необхідне для вибору обладнання та розподіл нормальних напружень на інструменті, що деформує.Purpose. Determination of hydraulic forging’s parameters of manufacturing of tubular workpieces made of steel 20Х17Н2 for firearm barrels by finite element method. Design/ methodology/ approach. The analysis of existing methods of manufacturing submachine gun’s barrels was made and as result of which more efficient and productive method of manufacturing of tubular products by hydraulic forging on smooth work holder was chosen. The mathematical model of process was worked out for analysis and numerical modeling was carried out by FEM. The possibility of realization of hydraulic forging of workpieces made of steel 20Х17Н2 and required parameters were determined. The final workpieces geometry, which are deformed, and mode of deformation were obtained. For the selection of equipment the load of process and normal stress distribution on tool were determined. Findings. As result of analysis, data with physical-mechanical characteristics of material after deformation, data for designing and constructing of die tooling and selection of required equipment were determined. Originality/value. Present work is actual in different branches of industry, and especially, in defence industry.В данной работе численным моделированием методом конечных элементов проведено анализ, гидропрессования на гладкой оправке, показана возможность получения заготовок для ствола пистолет-пулемета из стали 20Х17Н2. Моделирование процесса осуществлялось в программном пакете DEFORM, как осесимметричная задача. Определено возможность реализации процесса, необходимое гидростатическое давление, что прикладывается на свободную поверхность заготовки при гидропрессовании и распределение степени использования пластичности. Получено конечную геометрию деформируемой заготовки та параметры напряженно-деформированного состояния, определено усилие необходимое для выбора оборудования и распределение нормальных напряжений на инструменте

Electromagnetic wave refraction at an interface of a double wire medium

Plane-wave reflection and refraction at an interface with a double wire medium is considered. The problem of additional boundary conditions (ABC) in application to wire media is discussed and an ABC-free approach, known in the solid state physics, is used. Expressions for the fields and Poynting vectors of the refracted waves are derived. Directions and values of the power density flow of the refracted waves are found and the conservation of the power flow through the interface is checked. The difference between the results, given by the conventional model of wire media and the model, properly taking into account spatial dispersion, is discussed.Comment: 17 pages, 11 figure

Effects of Pilates mat exercises on muscle strength and on pulmonary function in patients with cystic fibrosis

Objective: To analyze the effects of Pilates mat exercises in patients with cystic fibrosis (CF). Methods: This was a clinical trial involving 19 CF patients recruited from either the CF Outpatient Clinic of the State University at Campinas Hospital de Clinicas or the Children's Institute of the University of So Paulo School of Medicine Hospital das Clinicas. All of the patients performed Pilates mat exercises for four months (one 60-min session per week). the variables studied (before and after the intervention) were respiratory muscle strength, MIP, MEP, FVC, and FEV1. Results: After the intervention, MIP was significantly higher in the male patients (p = 0.017), as were MIP and MEP in the female patients (p = 0.005 and p = 0.007, respectively). There were no significant differences between the pre- and post-intervention values of FVC or FEV1, neither in the sample as a whole nor among the patients of either gender. Conclusions: Our results show that Pilates mat exercises have beneficial effects on respiratory muscle strength in CF patients.Univ Estadual Campinas, Campinas, SP, BrazilUniv Estadual Campinas, Programa Posgrad Saude Crianca & Adolescente, Campinas, SP, BrazilUniv Estadual Campinas, Dept Pediat, Fac Ciencias Med, Campinas, SP, BrazilUniv São Paulo, Fac Med, Inst Crianca, Unidade Pneumol Pediat, São Paulo, BrazilUniversidade Federal de São Paulo, Programa Posgrad Reabilitacao, São Paulo, BrazilUniversidade Federal de São Paulo, Programa Posgrad Reabilitacao, São Paulo, BrazilWeb of Scienc