Characterizations of the sphere by means of visual cones: an alternative proof of Matsuura's theorem

In this work we prove that if there exists a smooth convex body $M$ in the Euclidean space $\mathbb{R}^n$, $n\geq 3$, contained in the interior of the unit ball $\mathbb{S}^{n-1}$ of $\mathbb{R}^n$, and point $p\in \mathbb{R}^n$ such that, for each point of $\mathbb{S}^{n-1}$, $M$ looks centrally symmetric and $p$ appears as the centre, then $M$ is an sphere

A process centred virtual approach to support cost estimating along product life cycle

The application of engineering practices and scientific principles to the creation of cost estimates along a product life cycle is one of the basic aspects of Cost Engineering. Cost estimates are used as fundamental criteria to make design decisions in the development stage and also to make business decisions in collaboration between OEMs and their supply chain. The achievement of an estimate requires experience and knowledge of different techniques and methodologies. Key aspects on its creation are the adoption of a cost estimating process, the availability of the needed data and the proper management of the information used during the process. The collaboration between the OEM and its supplier can be facilitated by having a better common understanding of how the cost estimates have been created. The cost estimating process used is then a fundamental piece of trust. In this context, the main purpose of this paper is to present the research conducted in the definition of cost estimating processes and the virtual framework selected. They are the key elements in the development of a prototype set of virtual tools to support the creation of cost estimates, the improvement of competences of the Cost Engineering Community, and the common understanding on cost between OEMs and their supply chain

Signatures of Planets in Spatially Unresolved Disks

Main sequence stars are commonly surrounded by debris disks, composed of cold dust continuously replenished by a reservoir of undetected dust-producing planetesimals. In a planetary system with a belt of planetesimals (like the Solar System's Kuiper Belt) and one or more interior giant planets, the trapping of dust particles in the mean motion resonances with the planets can create structure in the dust disk, as the particles accumulate at certain semimajor axes. Sufficiently massive planets may also scatter and eject dust particles out of a planetary system, creating a dust depleted region inside the orbit of the planet. In anticipation of future observations of spatially unresolved debris disks with the Spitzer Space Telescope, we are interested in studying how the structure carved by planets affects the shape of the disk's spectral energy distribution (SED), and consequently if the SED can be used to infer the presence of planets. We numerically calculate the equilibrium spatial density distributions and SEDs of dust disks originated by a belt of planetesimals in the presence of interior giant planets in different planetary configurations, and for a representative sample of chemical compositions. The dynamical models are necessary to estimate the enhancement of particles near the mean motion resonances with the planets, and to determine how many particles drift inside the planet's orbit. Based on the SEDs and predicted $\it{Spitzer}$ colors we discuss what types of planetary systems can be distinguishable from one another and the main parameter degeneracies in the model SEDs.Comment: 40 pages (pre-print form), including 16 figures. Published in ApJ 200

Construction and validation of a questionnaire to assess student satisfaction with mathematics learning materials

Sixth Edition Technological Ecosystems for Enhancing MulticulturalityMathematics is an essential branch for the scientific development and its study is mandatory in most university degrees. However, currently the level of academic performance and motivation of students to learn this science is not the desired one. The students can use different learning tools inside and outside the math classroom, enhancing the quality of the learning materials that are designed essentially to facilitate the learning of mathematics. The present research project aims to determine the validity and reliability of a measurement instrument that allows theassessment of the satisfaction of the students with the availablelearning materials. To fulfill the objectives of this research, the method of survey was used. A study with a quantitative approach was developed, which led to the design and validation of a questionnaire by a group of 7 experts. The validation closed after applying a pilot study with 728 students. It concluded positively, obtaining nine factors that coincide with the revision of the literature: technological quality, quality of content, visual quality, didactic significance, adequacy of content, relationship between theory and practice, involvement, contribution to learning, relevance and interaction between educational actors. The results of this questionnaire provide to the international scientific community with relevant information for the design, selection, and use of study materials in the classrooms, which will contribute to raising the levels of student engagement, and their academic performance in mathematics, secondaril

Integral representation of one dimensional three particle scattering for delta function interactions

The Schr\"{o}dinger equation, in hyperspherical coordinates, is solved in closed form for a system of three particles on a line, interacting via pair delta functions. This is for the case of equal masses and potential strengths. The interactions are replaced by appropriate boundary conditions. This leads then to requiring the solution of a free-particle Schr\"{o}dinger equation subject to these boundary conditions. A generalized Kontorovich - Lebedev transformation is used to write this solution as an integral involving a product of Bessel functions and pseudo-Sturmian functions. The coefficient of the product is obtained from a three-term recurrence relation, derived from the boundary condition. The contours of the Kontorovich-Lebedev representation are fixed by the asymptotic conditions. The scattering matrix is then derived from the exact solution of the recurrence relation. The wavefunctions that are obtained are shown to be equivalent to those derived by McGuire. The method can clearly be applied to a larger number of particles and hopefully might be useful for unequal masses and potentials.Comment: 18 pages, 2 figures, to be published in J. Math. Phy

Probing for Exoplanets Hiding in Dusty Debris Disks: Disk Imaging, Characterization, and Exploration with HST/STIS Multi-Roll Coronagraphy

Spatially resolved scattered-light images of circumstellar (CS) debris in exoplanetary systems constrain the physical properties and orbits of the dust particles in these systems. They also inform on co-orbiting (but unseen) planets, systemic architectures, and forces perturbing starlight-scattering CS material. Using HST/STIS optical coronagraphy, we have completed the observational phase of a program to study the spatial distribution of dust in ten CS debris systems, and one "mature" protoplanetrary disk all with HST pedigree, using PSF-subtracted multi-roll coronagraphy. These observations probe stellocentric distances > 5 AU for the nearest stars, and simultaneously resolve disk substructures well beyond, corresponding to the giant planet and Kuiper belt regions in our Solar System. They also disclose diffuse very low-surface brightness dust at larger stellocentric distances. We present new results inclusive of fainter disks such as HD92945 confirming, and better revealing, the existence of a narrow inner debris ring within a larger diffuse dust disk. Other disks with ring-like sub-structures, significant asymmetries and complex morphologies include: HD181327 with a posited spray of ejecta from a recent massive collision in an exo-Kuiper belt; HD61005 suggested interacting with the local ISM; HD15115 & HD32297, discussed also in the context of environmental interactions. These disks, and HD15745, suggest debris system evolution cannot be treated in isolation. For AU Mic's edge-on disk, out-of-plane surface brightness asymmetries at > 5 AU may implicate one or more planetary perturbers. Time resolved images of the MP Mus proto-planetary disk provide spatially resolved temporal variability in the disk illumination. These and other new images from our program enable direct inter-comparison of the architectures of these exoplanetary debris systems in the context of our own Solar System.Comment: 109 pages, 43 figures, accepted for publication in the Astronomical Journa

Physicochemical Characterization And Antioxidant Capacity Of Pitanga Fruits (eugenia Uniflora L.) [caracterização Fisico-química E Capacidade Antioxidante De Pitangas (eugenia Uniflora L.)]

This study was carried out to obtain more information about the physicochemical properties, composition, and antioxidant activity of pitanga fruits (Eugenia uniflora L.), particularly fruits from the State of Rio Grande do Sul, Brazil. Pitanga with different flesh colors (purple, red, and orange) from tree selections cultivated at Embrapa Clima Temperado (RS-Brazil) were analyzed. Only slight differences were observed in the quality parameters and in the proximate and fatty acid compositions among the fruits studied. The extracts from purple-fleshed pitanga had the highest total phenolic and anthocyanin contents along with the highest antioxidant capacity. The antioxidant capacity (DPPH and FRAP assays) of methanolic pitanga extracts was highly correlated with the total phenolic content, but in ethanolic extracts, the anthocyanin content was correlated only with the FRAP antioxidant capacity. Orange fleshed pitanga had higher β-cryptoxanthin and β-carotene levels than those of the red fruit, which had higher lycopene content. The results indicate that the purple-fleshed pitanga, cultivated in Rio Grande do Sul, is a rich source of phenolic compounds and has high antioxidant capacity. The red and orange-fleshed pitanga, on the other hand, are rich sources of carotenoids.311147154Abidille, M.D.H., Antioxidant activity of the extracts from Dillenia indica fruits (2005) Food Chemistry, 90 (4), pp. 891-896Adebajo, A.C., Oloki, K.J., Aladesanmi, A., Antimicrobial activity of the leaf extract of Eugenia uniflora (1989) Journal of Phytotherapy Resource, 3 (6), pp. 258-259Aherne, S.A., O'Brien, N.M., Dietary flavonols: Chemistry, food content, and metabolism (2002) Nutrition, 18 (1), pp. 75-81(1995) Official methods of analysis of the Association of the Official Analytical Chemists, , ASSOCIATION OF OFFICIAL ANALYTICAL CHEMISTS-AOAC, 16th ed. Arlington, Virginia: AOACAzevedo-Meleiro, C.H., Rodriguez-Amaya, D.B., Confirmation of the identity of the carotenoids of tropical fruits by HPLC-DAD and HPLC-MS (2004) Journal of Food Composition and Analysis, 17 (3-4), pp. 385-396Bagetti, M., Antioxidant capacity and composition of pitanga seeds (2009) Ciência Rural, 39 (8), pp. 204-2510Beekwilder, J., Antioxidant in raspberry: On-line analysis links antioxidant activity to a diversity of individual metabolites (2005) Journal of Agricultural and Food Chemistry, 53 (9), pp. 3313-3320Benzie, F.F.I., Strain, J.J., The ferric reducing ability of plasma (FRAP) as a measure of "antioxidant power": The FRAP assay (1996) Analytical Biochemistry, 239 (1), pp. 70-76Bligh, E.G., Dyer, W.J., A rapid method of total lipid extraction and purification (1959) Journal of Biochemistry and Physiology, 37 (8), pp. 911-917Block, G., Patterson, B., Subar, A., Fruits, vegetables and cancer prevention: A review of the epidemiological evidence (1992) Nutrition and Cancer, 18 (1), pp. 1-29Bors, W., Flavonoids as antioxidants: Determination of radical scavenging efficiencies (1990) Methods in Enzymology, 186, pp. 343-355Brand-Williams, W., Cuvelier, M.E., Berset, C., Use of a free radical method to evaluated antioxidant activity (1995) Lebensmittel-Wissenschaft und-Technologie, 28 (1), pp. 25-30Regulamento técnico geral para fixação dos padrões de identidade e qualidade para polpa de fruta (2000) Diário Oficial da República Federativa do Brasil, p. 54. , http://extranet.agricultura.gov.br/sislegisconsulta/consultarLegislacao. do?operacao=visualizar&id=7777, BRASIL. Instrução Normativa, no 1, de 7 de janeiro de 2000, Brasília, DF, 10 jan, Seção 1, Disponível em:, Acesso em: 18 dez. 2008Cavalcante, M.L., Rodriguez-Amaya, D.B., Carotenoid composition of the tropical fruits Eugenia uniflora and Malpighia glabra (1992) Food Science and Human Nutrition, pp. 643-650. , In: CHARALAMBOUS, G. (Ed.), Amsterdam: Elsevier Science PublishersClinton, S.K., Lycopene: Chemistry, biology, and implications for human health and disease (1998) Nutrition Reviews, 56 (2), pp. 35-51Consolini, A.E., Sarubbio, M., Pharmacological effects of Eugenia uniflora L. (Myrtaceae) aqueous extract on rat's heart (2002) Journal of Ethnopharmacology, 81 (1), pp. 57-63di Mascio, P., Kaiser, S., Sies, H., Lycopene as the most efficient biological carotenoid singlet oxygen quencher (1989) Archives of Biochemistry and Biophysics, 274 (2), pp. 532-538Dillard, C.J., German, J.B., Phytochemicals: Neutraceuticals and human health (2000) Journal of the Science of Food and Agriculture, 80 (12), pp. 1744-1756Diplock, A.T., Functional food sciences and defense against reactive oxidative species (1998) British Journal of Nutrition, 80 (1), pp. 77-112Escarpa, A., Gonzalez, M.C., Approach to the content of total extractable phenolic compounds from different food samples by comparison of chromatographic and spectrophotometric methods (2001) Analytica Chimica Acta, 427 (1), pp. 119-127Gemtchüjnicov, I.D., (1976) Manual de taxonomia vegetal: Plantas de interesse econômico, agrícola, ornamentais e medicinais, p. 368. , São Paulo: CeresGenovese, M.I., Bioactive compounds and antioxidant capacity of exotic fruits commercial frozen pulps from Brazil (2008) Food Science and Technology International, 4 (3), pp. 207-214Hartman, L., Lago, B.C., A rapid preparation of fatty methyl esters from lipids (1973) Laboratory Practice, 22 (6), pp. 475-477Hassimotto, N.M.A., Genovese, M.I., Lajolo, F.M., Antioxidant activity of dietary fruits, vegetables, and commercial frozen fruit pulps (2005) Journal of Agricultural and Food Chemistry, 53 (8), pp. 2928-2935Kaur, C., Kapoor, H., Antioxidants in fruits and vegetables-the millennium's health (2001) International Journal of Food Science and Technology, 36 (7), pp. 703-725Kimura, M., Rodriguez-Amaya, D.B., Yokoyama, S.M., Cultivar differences and geographic effects on the carotenoid composition and vitamin A value of papaya (1991) Lebensmittel-Wissenschaft und-Technologie, 24 (5), pp. 415-418Krinsky, N.I., Johnson, E.J., Carotenoid actions and their relation to health and disease (2005) Molecular Aspects of Medicine, 26 (6), pp. 459-516Kris-Etherton, P.M., Bioactive compounds in foods: Their role in the prevention of cardiovascular disease and cancer (2002) American Journal of Medicine, 113 (9), pp. 71-88Kuskoski, M.E., Frutas tropicais silvestres e polpas de frutas congeladas: Atividade antioxidante, polifenóis e antocianinas (2006) Ciência Rural, 36 (4), pp. 1283-1287Lees, D.H., Francis, F.J., Standardization of pigment analyses in cranberries (1972) Hortscience, 7 (1), pp. 83-84Lima, V.L.A.G., Mélo, E.A., Lima, D.E.S., Fenólicos e carotenóides totais em pitanga (2002) Scientia Agricola, 59 (3), pp. 447-450Niizu, P.Y., Rodriguez-Amaya, D.B., A melancia como fonte de licopeno (2003) Revista do Instituto Adolfo Lutz, 62 (3), pp. 195-199Oliveira, A.L., Volatile compounds from pitanga fruit (Eugenia uniflora L.) (2006) Food Chemistry, 99 (1), pp. 1-5Padula, M., Rodriguez-Amaya, D.B., Characterization of the carotenoids and assessment of the vitamin A value of Brazilian guavas (Psidium guajava L.) (1986) Food Chemistry, 20 (1), pp. 11-19Pellegrini, N., Evaluation of antioxidant capacity of some fruit and vegetable foods: Efficiency of extraction of a sequence of solvents (2007) Journal of the Science of Food and Agriculture, 87 (1), pp. 103-111Pietta, P.G., Flavonoids as antioxidants (2000) Journal of Natural Products, 63 (7), pp. 1035-1042Pinto, M.S., Lajolo, F.M., Genovese, M.I., Bioactive compounds and quantification of total ellagic acid in strawberries (Fragaria × ananassa Duch.) (2007) Food Chemistry, 107 (4), pp. 1629-1635Porcu, O.M., Rodriguez-Amaya, D.B., Variation in the carotenoid composition of the lycopene-rich Brazilian fruit Eugenia uniflora L (2008) Plant Foods for Human Nutrition, 63 (4), pp. 195-199Prior, R.L., Cao, G., Antioxidant phytochemicals in fruits and vegetables: Diet and health implications (2000) Horticulture Science, 35 (4), pp. 588-592Rahman, I., Adcock, I.M., Oxidative stress and redox regulation of lung inflammation in COPD (2006) European Respiratory Journal, 28 (1), pp. 219-242Reynerston, K.A., Quantitative analysis of antiradical phenolic constituents from fourteen edible Myrtaceae fruits (2008) Food Chemistry, 109 (4), pp. 883-890Robards, K., Antolovich, M., Analytical chemistry of fruit bioflavonoids (1997) Analyst, 122, pp. 11R-34RRodriguez-Amaya, D.B., (1999) A guide to carotenoid analysis in foods, , Washington, D.C.: ILSI PressSalgado, S.M., Guerra, N.B., Melo Filho, A.B., Frozen fruit pulps: Effects of the processing on dietary fiber contents (1999) Brazilian Journal of Nutrition, 12 (3), pp. 303-308Scalzo, J., Plant genotype affects total antioxidant capacity and phenolic contents in fruit (2005) Nutrition, 21 (2), pp. 207-213Singleton, V.L., Rossi Jr., J.A., Colorimetry of total phenolic with phosphomolybdic-phosphotungstic acid reagents (1965) American Journal of Enology and Viticulture, 16 (3), pp. 144-158Stahl, W., Sies, H., Bioactivity and protective effects of natural carotenoids (2005) Biochimica et Biophysica Acta, 1740 (2), pp. 101-107Tapiero, H., Townsend, D.M., Tew, K.D., The role of carotenoids in the prevention of human pathologies (2004) Biomedicine and Pharmacotherapy, 58 (2), pp. 100-110(2006) Tabela brasileira de composição de alimentos-TACO, p. 113. , UNIVERSIDADE DE CAMPINAS-UNICAMP, 2. ed. Version II. Campinas: NEPA/UNICAMPVison, J.A., Phenol antioxidant quantity and quality in foods: Vegetables (1998) Journal of Agricultural and Food Chemistry, 46 (9), pp. 4113-4117Weyerstahl, P., Volatile constituents of Eugenia uniflora leaf oil (1988) Planta Médica, 54 (6), pp. 546-54

Molecular dynamics simulation of the nanoindentation process in Cr/CrN and (Cr/CrN)2 thin films

Molecular dynamics (MD) simulations were carries out for studying the influenceof nanoindentation in the atomistic deformation mechanisms of Cr/CrN and(Cr/CrN)2 coatings with BCC and FCC crystalline structures for Cr and CrN,respectively. The Morse potential was employed in order to determine the atomicinteraction forces of the Cr-Cr and Cr-N atoms. A non-deformable potential solidsphere was implemented for determining the role of the nanoindenter. The OliverParr method (OP) was used to obtain the hardness and elastic modulus of the Cr/CrN and (Cr/CrN)2 layers, resulting in values of 18 and 20 GPa for Cr/CrN and (Cr/CrN)2, respectively. The Cheng method was used for correcting the hardness values obtained by the OP method. The Cheng correction showed higher hardness values since it avoids the influence of the scale effect. Regarding the elasticity modulus, Cr/CrN and (Cr/CrN)2 exhibited values of 217.86 GPa and 258.9 GPa, respectively. Simulations of the temperature influence on the hardness were carried out over a range of 300-1000 K. Results indicate that the hardness decreased as a function of the temperature.Fil: Amaya Roncancio, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Arias Mateus, D. F.. Universidad Católica de Pereira; ColombiaFil: Segura Giraldo, B.. Universidad Nacional de Colombia; ColombiaFil: de la Roche, J.. Universidad Nacional de Colombia; ColombiaFil: Restrepo Parra, E.. Universidad Nacional de Colombia; Colombi

Application of Robot Programming to the Teaching of Object-Oriented Computer Languages

Object-oriented programming (OOP) abstract concepts are often difficult to understand for students, since it is not easy to find the equivalence of such concepts in daily life. In this paper we will study if an interdisciplinary approach based on an introduction to robotics and robot programming helps the student in acquiring theOOPconcepts. For our experiments, we selected a sample of thirty individuals among students with an adequate knowledge of procedural programming. This sample was divided into two groups of fifteen students each: for the first one we used a standard introductory approach to C#, whereas for the second one we developed an experimental course that included a demonstration program that illustrated OOP basic concepts using the features of a specific type of commercial ball-shaped robot with sensing, wireless communication and output capabilities. After the courses, both groups were evaluated by completing a multiple-choice exam and aC#programming exercise. Our results show that the student group that attended the course including the robot demo showed a higher interest level (i.e. they felt more motivated) than those students that attended the standard introductory C# course. Furthermore, the students from the experimental group also achieved an overall better mark

Valuing families' preferences for drug treatment: a discrete choice experiment

The burden on family members of those who are dependent on illicit drugs is largely unidentified despite the presence of significant negative financial, health and social impacts. This makes it difficult to provide appropriate services and support. This study aimed to assess the preferences for treatment attributes for heroin dependence among family members affected by the drug use of a relative and to obtain a measure of the intangible economic benefit. Discrete choice experiment. Data were analysed using mixed logit which accounted for repeated responses. Australia PARTICIPANTS: Eligible participants were Australian residents of 18+ years of age with a relative with problematic drug use. Complete data on 237 respondents were analysed; 21 invalid responses were deleted. Participant preference for likelihood of staying in treatment, family conflict, own health status, contact with police and monetary contribution to a charitable organisation providing treatment. All attributes were significant, and the results suggest there was a preference for longer time in treatment, less family discord, better own health status, less likelihood of their relative encountering police, and while they were willing to contribute to a charity for treatment to be available, they prefer to pay less not more. In order of relative importance, participants were willing to pay an additional $4.46 (95$42.00 (95% CI 28.30-55.69) to avoid 5 days per week of family discord, $87.94 (95$129.66 (95% CI 53.50-205.87) for each 1% decline in the chance of police contact. Drug treatment in Australia appears to have intangible benefits for affected family members. Families are willing to pay for treatment which reduces family discord, improves their own health, increases time in treatment and reduces contact with police. BACKGROUND AND AIMS DESIGN SETTING MEASUREMENTS FINDINGS CONCLUSION