The 1981 classic book by I. E. Irodov entitled “Problems in General Physics”, well known as Irodov among students, contains two problems of pursuit between particles with constant speeds in 2 dimensions that inspired variants in recent Physics Olympiads. In this paper, we present in a single text the most studied versions of these problems, including their solutions and computational simulations using advanced features of Desmos, a free online graphics system. Furthermore, we show the calculations of the exact pursuit curves and show that they coincide with the computer simulations. Finally, we consider new natural variants, such as pursuit involving more points at different trajectories, and we obtain computational results for them. 198 I E Problems Physics, , Physics” students Olympiads paper Desmos system Furthermore Finally trajectories them 19 1

O clássico livro de I. E. Irodov intitulado “Problems in General Physics” de 1981, bem conhecido como Irodov entre os estudantes, contém dois problemas de perseguição entre partículas com velocidades constantes em 2 dimensões que inspiraram variantes em recentes Olimpíadas de Física e vestibulares do IME e do ITA. Neste artigo, apresentamos em um único texto as versões mais estudadas desses problemas, incluindo soluções e simulações computacionais usando recursos avançados do Desmos, um sistema gráfico online e gratuito. Além disso, mostramos os cálculos das curvas exatas das trajetórias da perseguição nas variantes e mostramos que coincidem com as simulações computacionais. Finalmente, consideramos novas variantes naturais, como perseguição envolvendo mais pontos em diferentes trajetórias, e obtemos resultados computacionais para elas. I E Problems Physics 1981 estudantes ITA artigo Desmos gratuito disso Finalmente naturais elas 198 19 1

The 2007 classic book by David Morin entitled “Introduction to Classical Mechanics”, well known among students of Physics Olympiads, contains many exercises of coupled oscillations that inspired problems in recent exams. In this paper, we present these problems, including their solutions and computational simulations using advanced features of Desmos, a free online graphics system. Moreover, we show a more didactic general way of handling such problems, even the most complex ones, using Linear Algebra and Graph Theory. 200 Introduction Mechanics, Mechanics , Mechanics” Olympiads exams paper Desmos system Moreover ones Theory 20 2

O clássico livro de David Morin intitulado “Introduction to Classical Mechanics” de 2007, bem conhecido entre os estudantes de olimpíadas internacionais de Física, contém vários exercícios de oscilações acopladas que inspiraram problemas em provas recentes. Neste artigo, apresentamos esses problemas, incluindo soluções e simulações computacionais usando recursos avançados do Desmos, um sistema gráfico online e gratuito. Além disso, mostramos um modo geral mais didático de se compreender tais problemas, mesmo os mais complexos, combinando Álgebra Linear e Teoria dos Grafos. Introduction Mechanics 2007 Física recentes artigo Desmos gratuito disso complexos Grafos 200 20 2

ABSTRACT Objective: The present study investigated the time needed to achieve a steady state for an accurate assessment of resting energy expenditure (REE) in adolescents with healthy weight and obesity. Materials and methods: Thirty adolescents aged 12-17 years were assigned to a group with healthy weight (GHW; n = 12, body mass index [BMI] 22.5 ± 3.6 kg/m2) and another group with obesity (GO; n = 18, BMI 34.1 ± 5.2 kg/m2). Participants underwent test-retest reliability of REE assessment as follows: a) 24 h of abstention from physical exercise, soft drinks, or caffeine; b) fasting for ~12 h; c) acclimation period of 10 min; d) 30-min assessment in a supine position. Results and discussion: A significant change occurred during the 30 min in REE. Significant differences existed between consecutive means until the 20th and 25th min for the GHW and GO, respectively. Although significant differences between trials 1 and 2 were detected during the first 5-10 min of assessment, the REE for each 5-min time point exhibited high test-retest reliability across trials in both groups (intraclass correlation coefficients range 0.79-0.99). Conclusion: The following recommendations are provided to promote accurate assessment of REE among adolescents: a) initiate the REE assessment with 10 min of acclimation to decrease restlessness; b) determine REE for a minimum of 20 min if healthy weight and 25 min if obesity; c) determine REE for a further 5 min, with the average of this last 5 min of REE data being regarded as the REE.

OBJECTIVES: Few studies have investigated whether post-exercise hypotension (PEH) after concurrent exercise (CEX) is related to changes in cardiac output (Q) and systemic vascular resistance (SVR) in older individuals. We tested whether PEH after a single bout of CEX circuits performed in open-access facilities at the Third Age Academies (TAA) in Rio de Janeiro City (Brazil) would be concomitant with decreased Q and SVR in individuals aged ≥60 years with prehypertension. Moreover, we assessed autonomic modulation as a potential mechanism underlying PEH. METHODS: Fourteen individuals (age, 65.8±0.9 y; systolic/diastolic blood pressure [SBP/DBP], 132.4±12.1/72.8±10.8 mmHg; with half of the patients taking antihypertensive medications) had their blood pressure (BP), heart rate (HR), Q, SVR, HR variability (HRV), and spontaneous baroreflex sensitivity (BRS) recorded before and 50 min after CEX (40-min circuit, including seven stations of alternate aerobic/resistance exercises at 60-70% HR reserve) and non-exercise control (CONT) sessions. The study protocol was registered in a World Health Organization-accredited office (Trial registration RBR-7BWVPJ). RESULTS: SBP (Δ=−14.2±13.1 mmHg, p=0.0001), DBP (Δ=−5.2±8.2 mmHg, p= 0.04), Q (Δ=−2.2±1.5 L/min, p=0.0001), and BRS (Δ=−3.5±2.6 ms/mmHg; p=0.05) decreased after CEX as compared with the CONT session. By contrast, the HR increased (Δ=9.4±7.2 bpm, p<0.0001), and SVR remained stable throughout the postexercise period as compared with the CONT session (Δ=0.10±0.22 AU, p=0.14). We found no significant difference between the CEX and CONT with respect to the HRV indexes reflecting autonomic modulation. CONCLUSION: CEX induced PEH in the older individuals with prehypertension status. At least in the first 50 min, PEH occurred parallel to the decreased Q and increased HR, while SVR was not different. The changes in autonomic outflow appeared to be unrelated to the acute cardiac and hemodynamic responses.

Abstract Aim: Spinal cord injury (SCI) is associated with changes in cardiac autonomic control, that can be evaluated by heart rate variability (HRV), for which the electrocardiogram (ECG) is the gold standard. However, the use of ECG is limited to laboratory environments, and new tools are needed for this purpose and that can be applied in the routine monitoring of individuals with SCI. The present study aimed to investigate the validity of the Polar V800 heart rate monitor in assessing the cardiac autonomic control of individuals with SCI. Methods: Nineteen adult men with SCI (paraplegia n = 10; 44.5 ± 8.5 years and tetraplegia n = 9; 34.4 ± 7.5 years) participated in this cross-sectional study. The participants remained in the sitting position at rest for 10 min for the acquisition of the ECG and Polar V800 signals. The last 5-min window was used to count the beat-by-beat R-R interval series and then calculate the HRV indices (linear methods in the time and frequency domains). The study subgroups were compared, and the validity of the measurements generated with a heart rate monitor was determined using the intraclass correlation coefficient (ICC2,1) and Bland-Altman graphs. Results: Agreement analyses for the R-R intervals, SDNN, rMSSD, PNN50, SD1, LF, HF, and LF: HF ratio tended to show reliability ranging from acceptable to excellent (ICC = 0.579-0.990; P = 0.043-0.001) and acceptably narrow limits of agreement within both the group with tetraplegia and the group with paraplegia. Conclusion: The Polar V800 heart rate monitor is a valid instrument for assessing HRV in individuals with paraplegia and tetraplegia.

This manuscript reports the synthesis of twenty 3,5-diaryl-1,2,4-oxadiazole derivatives, nine of which are novel compounds. The amidoxime reaction with acyl chlorides obtained from substituted benzoic acids was used. All compounds were tested against five standard (American Type Culture Collection (ATCC)) bacteria: Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Proteus mirabilis and Staphylococcus aureus. Screening assays were carried out using agar-diffusion technique, in which 100 µM heterocyclic compounds solutions (20% dimethylsulfoxide/water) were employed. The minimum inhibitory concentrations (MIC) of the active compounds were determined by serial dilutions at decreasing concentrations in microtiter plates. The nitrated derivatives gave the best test results, where MIC = 60 µM (E. coli) was the lowest value found for an ortho-nitrated derivative. The activity of these compounds possibly involves a mechanism via free radicals. S. aureus and P. aeruginosa were resistant to all compounds.

RESUMO: O artigo traz reflexões sobre a criação jurídica das comunidades remanescentes de quilombos, a implementação de políticas públicas e as consequências de tais medidas para agrupamentos que reivindicam reconhecimento de suas identidades quilombolas pelo Estado brasileiro. A investigação tem como eixos a compreensão histórica da organização quilombola, a discussão sobre as políticas afirmativas direcionadas aos quilombolas e a proposta de funcionamento da cultura e do território como dispositivos étnico-comunicacionais.

ABSTRACT: The article reflects on the legal establishment of the remaining quilombo communities, the implementation of public policies and the consequences of such measures for groups in demand of recognition of their quilombola identities by the Brazilian state. The investigation focuses on historical understanding of the quilombola organization, the discussion about affirmative policies directed to quilombolas and the functioning of the proposed culture and territory as ethnic-communicational devices.

A influência da estimulação transcraniana por corrente contínua (ETCC) sobre o desempenho da força muscular em exercícios que recrutam grandes massas musculares ainda não foi estabelecido em populações saudáveis. O objetivo desse estudo foi investigar se a ETCC anódica seria capaz de aumentar o desempenho durante exercício máximo de força (EMF) em sujeitos saudáveis. Catorze voluntários (idade: 26 ± 4 anos) executaram dois EMF com aplicação prévia da ETCC anódica ou placebo (2mA; 20 mim), envolvendo músculos flexores e extensores do joelho dominante em ação concêntrica isocinética (3 séries de 10 repetições). A atividade elétrica muscular (sEMG) de quatro músculos recrutados foi registrada durante o EMF. A ETCC anódica não foi capaz de melhorar a produção de força (trabalho total e pico de torque), resistência à fadiga ou atividade eletromiográfica durante o EMF, quando comparada à condição placebo. Em conclusão, a ETCC anódica aplicada sobre o córtex motor contralateral não foi capaz de aumentar o desempenho de força de flexores e extensores de joelho em jovens saudáveis.

The influence of transcranial direct current stimulation (tDCS) upon maximal strength performance in exercises recruiting large muscle mass has not been established in healthy populations. The purpose of this study was to investigate whether anodal tDCS was able to increase the performance during maximal strength exercise (MSEX) in healthy subjects. Fourteen volunteers (age: 26 ± 4 yrs) performed two MSEX after anodal or sham tDCS (2mA; 20min prior MSEX), involving knee extensors and flexors in concentric isokinetic muscle actions of the dominant limb (3 sets of 10 repetitions). The electrical muscle activity (sEMG) of four recruited muscles was recorded during MSEX. Anodal tDCS was not able to improve force production (i.e., total work and peak torque), fatigue resistance, or electromyographic activity during MSEX when compared to sham condition. In conclusion, anodal tDCS applied upon the contralateral motor cortex was not capable of increasing the strength performance of knee extensors and flexors in young healthy subjects.

La influencia de estimulación transcraneal de corriente directa (tDCS) en ejercicios de fuerza muscular de rendimiento que reclutan grandes masas musculares no se ha establecido en la población sana. El objetivo de este estudio fue investigar si la ETCC anódica podría mejorar el rendimiento durante el ejercicio máximo de la fuerza (EMF) en sujetos sanos. Catorce voluntarios (26 ± 4 años de edad) realizaron dos EMF con la aplicación previa de ETCC anódica y placebo (2 mA, 20 i) la participación de los flexores y extensores de la rodilla dominante en acción concéntrica (3 series de 10 repeticiones). La actividad eléctrica muscular (sEMG) en cuatro músculos reclutados se registró durante el EMF. La ETCC anódica no fue capaz de mejorar la potencia de salida (trabajo total y pico de torque), la resistencia a la fatiga o la actividad electromiográfica durante el EMF, cuando comparada con la condición placebo. Por lo tanto, la ETCC anódica aplicada a la corteza motora contralateral no fue capaz de aumentar el rendimiento de la fuerza de flexores y extensores de la rodilla en jóvenes sanos.

Este trabalho estudou o Índice de Sustentabilidade Empresarial (ISE) da Bolsa de Mercadorias e Futuros e Bolsa de Valores de São Paulo (BM&FBOVESPA), com o objetivo principal de analisar o desempenho histórico dos investimentos sustentáveis no mercado acionário brasileiro, considerando o período de dezembro de 2005 a dezembro de 2010. Foram utilizados, principalmente, os seguintes índices de desempenho: Sharpe, Treynor, Jensen, Sortino, Modigliani & Modigliani e Omega. Concluiu-se que, embora os investimentos sustentáveis tenham registrado características interessantes no mercado acionário brasileiro, tais como baixo risco diversificável e aumento de liquidez, não obtiveram, no período de análise, um desempenho financeiro satisfatório. À medida que a adoção de critérios que exijam elevado desempenho das empresas no que tange às questões sobre sustentabilidade se tornar obrigatória, esses investimentos tenderão à valorização.

We studied the Corporate Sustainability Index (ISE) of the Brazilian Mercantile, Futures and Stock Exchange (BM&FBOVESPA), with the main objective of analyzing the performance of sustainable investments in the Brazilian stock market during the period from December 2005 to December 2010. We mainly used the following measures: Sharpe, Treynor, Jensen, Sortino, Modigliani and Modigliani, and Omega. Our results show that although sustainable investments exhibited some interesting characteristics, such as low diversifiable risk and increasing liquidity, they did not achieve satisfactory financial performance in the analysis period. As the adoption of criteria that demand high performance of companies in relation to sustainability issues becomes mandatory, the value of these investments will tend to increase.

OBJETIVO: Avaliar a amplitude de movimentos (ADM) do joelho após seis meses de pós-operatório de artroplastia total, comparando-a com o seu valor pré-operatório. MATERIAL E MÉTODOS: Foi analisada a amplitude de movimento de 80 artroplastias, com acompanhamento pós-operatório médio de 21,9 meses. RESULTADO: Não houve diferença significativa entre as médias pré e pós-operatória, de extensão (p=0,09) e flexão (p=0,47). Subdividindo os pacientes em dois grupos, naqueles com flexão pré-operatória menor ou igual a 90° (n=17) observou-se aumento significativo da flexão (p=0,000037). Naqueles com flexão pré-operatória maior ou igual a 120° (n=31) ocorreu diminuição significativa da flexão (p=0,000068). Quatro pacientes foram submetidos à manipulação, em média com 2,1 meses de pós-operatório. A média de flexão antes da manipulação e após seis meses dessa foi significativamente diferente (p=0,0068). Já as médias de flexão pré-operatória e após seis meses de pós-operatório foram semelhantes (p=0,28). CONCLUSÃO: A flexão pré-operatória influencia de forma significativa a flexão após artroplastia total do joelho. Sua medida fornece ao cirurgião bom parâmetro para prevê-la.

OBJECTIVE: To evaluate knee range of motion (ROM) after at least six months postoperatively in total knee arthroplasty, by comparing it to baseline value. MATERIALS AND METHODS: Ranges of motion of eighty arthroplasties were analyzed within an average follow-up of 21.9 months. RESULTS: No significant differences between pre- and postoperative averages for extension (p=0.09) and flexion (p=0.47) were found. By dividing the patients into two groups, a significant flexion improvement was seen in those with pre-op flexion equal or smaller than 90º (n=17) (p=0.000037). In the other group, a significant decrease in flexion was seen in those with pre-op flexion equal or greater than 120º (n=31) (p=0.000068). Four patients have been submitted to knee manipulations within an average of 2.1 months postoperatively. The mean flexion rate before manipulation and after six months was significantly different (p=0.0068). The mean pre-op flexion and after six months postoperatively was similar (p=0.28). CONCLUSION: Preoperative flexion significantly influences the post-op flexion in total knee arthroplasty. Its measurement provides the surgeon with a good parameter for previewing this.