The 'spinning disk touches stationary disk' problem revisited: an experimental approach

A popular Newtonian mechanics problem, featured in textbooks, physics olympiads and forums alike, concerns two disks with different radii and moment of inertia that rotate differently and that touch each other. Most students struggle to calculate the final angular velocity of the disks, erroneously attempting to use different conservation laws. In this paper we propose a simple experiment that should help physics teachers explain this challenging exercise in an engaging way for the students. By using a smartphone/tablet and video analysis tools, the angular velocity of both disks can easily be tracked as a function of time, clearly showing the three stages of the interaction (before touching, only one disk rotating; touching with slippage; and touching without slippage). Processing and plotting of the data in a spreadsheet immediately shows which quantities are conserved and which are not. Several extensions to the core experiment are also suggested

The effect of a tangential frictional force on rotating disks: an experimental approach

This paper describes an experiment with two touching rotating disks, whose movement is followed by video analysis. Within the disks’ movements, there are intervals with sliding and intervals without sliding, that is, intervals with frictional forces between the touching surfaces and intervals without it. This system configuration allows for measurement of the changeable magnitudes and directions of frictional forces (much more difficult to set up with translational motion). This activity may be used to combat students misconceptions of “frictional force always opposes the motion” and “between the same two bodies, one gets the same frictional force,” commonly found in the classroom, or just to reinforce the rotational dynamics relationships

Patients- and physicians- priorities for improvement: The case of rheumatic diseases

OBJECTIVES: To compare the health priorities elected by patients with rheumatic diseases and by their attending rheumatologists. PATIENTS AND METHODS: We undertook a cross-sectional study among patients and rheumatologists in Portuguese rheumatology outpatient clinics. 75% of all Portuguese Rheumatology Departments agreed to participate. Rheumatologists from non-participating hospital departments were asked to collaborate through their private practices. All patients were eligible for inclusion except if they were under 18 years of age or had a mental disorder that would affect their participation. Data were collected through dedicated questionnaires. Patients were asked to indicate 3 priorities for improvement out of 12 health domains (Arthritis Impact Measurement Scale 2) regarding their rheumatic disease. Rheumatologists were asked similar questions focused around rheumatoid arthritis (RA) and osteoarthritis (OA). RESULTS: 1,868 patients and 56 rheumatologists entered the study. The most commonly selected priorities by patients with rheumatic diseases were: "Rheumatic pain" (70%), "Walking and bending" (45%), and "Hand and Finger Function" (40%). The main priority for improvement among patients with RA was "Rheumatic Pain" (69%), while rheumatologists more commonly elected "Work" (55%) as their main priority for these patients. Among patients with OA, "Rheumatic Pain" was the first priority for both patients and doctors (elected by 75%, and 55% of respondents, respectively). CONCLUSIONS: Our study showed discordance between the priorities for improvement elected by patients and by their respective physicians. This was more pronounced in RA than in OA. Studying and addressing such differences may support physicians and institutions to better achieve the prime goal of incorporating and responding to patients' needs and preferences

CiliarMove: new software for evaluating ciliary beat frequency helps find novel mutations by a Portuguese multidisciplinary team on primary ciliary dyskinesia

This study was supported by the Fundação para a Ciência e a Tecnologia (PTDC/BEXBID/1411/ 2014 research grant). S.S. Lopes was funded by FCT Investigator IF/00951/2012, by NOVA Medical School and by FCT CEEC-IND 2018. P. Sampaio was funded by the PhD fellowship FCT: SFRH/BD/111611/2015. M. Roxo-Rosa was funded by the UID/Multi/04462/2013-LISBOA-01-0145-FEDER-007344 grant (iNOVA4Health). C.M. Quintão was funded by Fundação para a Ciência e Tecnologia (UID/FIS/04559/2013). S.S. Lopes participates in and acknowledge financial support from the COST Action BEAT-PCD (BM1407). S.S. Lopes received funding from project LysoCil funded by the European Union Horizon 2020 research and innovation under grant agreement No 811087. Funding information for this article has been deposited with the Crossref Funder Registry.Evaluation of ciliary beat frequency (CBF) performed by high-speed videomicroscopy analysis (HVMA) is one of the techniques required for the correct diagnosis of primary ciliary dyskinesia (PCD). Currently, due to lack of open-source software, this technique is widely performed by visually counting the ciliary beatings per a given time-window. Our aim was to generate open-source, fast and intuitive software for evaluating CBF, validated in Portuguese PCD patients and healthy volunteers. Nasal brushings collected from 17 adult healthy volunteers and 34 PCD-referred subjects were recorded using HVMA. Evaluation of CBF was compared by two different methodologies: the new semi-automated computer software CiliarMove and the manual observation method using slow-motion movies. Clinical history, nasal nitric oxide and transmission electron microscopy were performed for diagnosis of PCD in the patient group. Genetic analysis was performed in a subset (n=8) of suspected PCD patients. The correlation coefficient between the two methods was R-2=0.9895. The interval of CBF values obtained from the healthy control group (n=17) was 6.18-9.17 Hz at 25 degrees C. In the PCD-excluded group (n=16), CBF ranged from 6.84 to 10.93 Hz and in the PCD group (n=18), CBF ranged from 0 to 14.30 Hz. We offer an automated open-source programme named CiliarMove, validated by the manual observation method in a healthy volunteer control group, a PCD-excluded group and a PCD-confirmed group. In our hands, comparisons between CBF intervals alone could discern between healthy and PCD groups in 78% of the cases.publishersversionpublishe

Methodological considerations for kinematic analysis of upper limbs in healthy and poststroke adults Part II: a systematic review of motion capture systems and kinematic metrics

To review the methods used to analyze the kinematics of upper limbs (ULs) of healthy and poststroke adults, namely the motion capture systems and kinematic metrics. A database of articles published in the last decade was compiled using the following search terms combinations: (“upper extremity” OR “upper limb” OR arm) AND (kinematic OR motion OR movement) AND (analysis OR assessment OR measurement). The articles included in this review: (1) had the purpose to analyze objectively three-dimension kinematics of ULs, (2) studied functional movements or activities of daily living involving ULs, and (3) studied healthy and/or poststroke adults. Fourteen articles were included (four studied a healthy sample, three analyzed poststroke patients, and seven examined both poststroke and healthy participants). Most articles used optoelectronic systems with markers; however, the presentation of laboratory and task-specific errors is missing. Markerless systems, used in some studies, seem to be promising alternatives for implementation of kinematic analysis in hospitals and clinics, but the literature proving their validity is scarce. Most articles analyzed “joint kinematics” and “end-point kinematics,” mainly related with reaching. The different stroke locations of the samples were not considered in their analysis and only three articles described their psychometric properties. Future research should validate portable motion capture systems, document their specific error at the acquisition place and for the studied task, include grasping and manipulation analysis, and describe psychometric properties.info:eu-repo/semantics/publishedVersio

Automated recognition of lung diseases in CT images based on the optimum-path forest classifier

The World Health Organization estimated that around 300 million people have asthma, and 210 million people are affected by Chronic Obstructive Pulmonary Disease (COPD). Also, it is estimated that the number of deaths from COPD increased 30% in 2015 and COPD will become the third major cause of death worldwide by 2030. These statistics about lung diseases get worse when one considers fibrosis, calcifications and other diseases. For the public health system, the early and accurate diagnosis of any pulmonary disease is mandatory for effective treatments and prevention of further deaths. In this sense, this work consists in using information from lung images to identify and classify lung diseases. Two steps are required to achieve these goals: automatically extraction of representative image features of the lungs and recognition of the possible disease using a computational classifier. As to the first step, this work proposes an approach that combines Spatial Interdependence Matrix (SIM) and Visual Information Fidelity (VIF). Concerning the second step, we propose to employ a Gaussian-based distance to be used together with the optimum-path forest (OPF) classifier to classify the lungs under study as normal or with fibrosis, or even affected by COPD. Moreover, to confirm the robustness of OPF in this classification problem, we also considered Support Vector Machines and a Multilayer Perceptron Neural Network for comparison purposes. Overall, the results confirmed the good performance of the OPF configured with the Gaussian distance when applied to SIM- and VIF-based features. The performance scores achieved by the OPF classifier were as follows: average accuracy of 98.2%, total processing time of 117 microseconds in a common personal laptop, and F-score of 95.2% for the three classification classes. These results showed that OPF is a very competitive classifier, and suitable to be used for lung disease classification

Opsoclonus-myoclonus-ataxia syndrome associated with chikungunya and dengue virus co-infection

Submitted by Ana Maria Fiscina Sampaio ([email protected]) on 2018-09-19T16:55:58Z No. of bitstreams: 1 Rosario MS Opsoclonus-Myoclonus-Ataxia Syndrome....pdf: 514736 bytes, checksum: 2d645cdbe4121ce8c8d637e1a2c7ed2d (MD5) Approved for entry into archive by Ana Maria Fiscina Sampaio ([email protected]) on 2018-09-19T17:27:26Z (GMT) No. of bitstreams: 1 Rosario MS Opsoclonus-Myoclonus-Ataxia Syndrome....pdf: 514736 bytes, checksum: 2d645cdbe4121ce8c8d637e1a2c7ed2d (MD5) Made available in DSpace on 2018-09-19T17:27:26Z (GMT). No. of bitstreams: 1 Rosario MS Opsoclonus-Myoclonus-Ataxia Syndrome....pdf: 514736 bytes, checksum: 2d645cdbe4121ce8c8d637e1a2c7ed2d (MD5) Previous issue date: 2018 CNPq-National Council for Scientific and Technological Development (302584/2015-3) and MCTI-Ministry of Science, Technology, Innovation/FINEP–Funding Authority for Studies and Projects/FNDCT–National Fund for the Development of Science and Technology (04160060-00/2016) Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / Secretaria Estadual da Saúde da Bahia. Hospital Geral Roberto Santos. Salvador, BA, Brasil Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / University of Rome Tor Vergata. Rome, Italy Secretaria Estadual da Saúde da Bahia. Hospital Geral Roberto Santos. Salvador, BA, Brasil / Universidade Federal da Bahia. Faculdade de Medicina. Salvador, BA, Brasil Secretaria Estadual da Saúde da Bahia. Hospital Geral Roberto Santos. Salvador, BA, Brasil University of Oxford. Department of Zoology. Oxford, UK Instituto Evandro Chagas. Centro de Tecnologia e Inovação. Ananindeua, PA, Brasil Instituto Evandro Chagas. Centro de Tecnologia e Inovação. Ananindeua, PA, Brasil Instituto Evandro Chagas. Centro de Tecnologia e Inovação. Ananindeua, PA, Brasil Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil Opsoclonus-myoclonus-ataxia syndrome (OMAS) is a rare neurological disorder characterized by irregular multidirectional eye movements, myoclonus, cerebellar ataxia, sleep disturbances, and cognitive dysfunction. Although most commonly related to paraneoplastic syndrome, this condition has occasionally been described following infectious illnesses. This article reports the first case of OMAS in association with chikungunya and dengue virus co-infection. The genetic analysis identified chikungunya virus of East/Central/South African genotype and dengue serotype 4 virus of genotype II. This report represents an unusual clinical syndrome associated with viral co-infection and reinforces the need for clinical vigilance with regard to neurological syndromes in the context of emergent arboviruses

Efeitos da suplementação de picolinato de cromo sobre a concentração da glicemia plasmática durante exercício físico e em repouso

O cromo é um mineral-traço essencial absorvido da alimentação, principalmente alguns alimentos como carnes e oleaginosas, sendo armazenado principalmente no fígado tendo como função primária um aumento na tolerância à glicose associado à insulina no metabolismo celular. O objetivo desse trabalho foi de averiguar os efeitos do cromo em sua versão Picolinato sobre a glicemia e como que ele manipula a concentração de glicose plasmática no organismo durante o exercício. Para tanto foram utilizados 17 indivíduos saudáveis fisicamente ativos que participaram de todas as fases do experimento o qual foi dividido em quatro fases distintas, grupo suplementado com 50g de maltodextrina em repouso (Malt), grupo suplementado com 50g de maltodextrina em exercício aeróbio (MEx), grupo suplementado com  50g de maltodextrina e mais 70 mcg de Picolinato de Cromo em repouso (MCro) e grupo suplementado com  50g de maltodextrina e mais 70 mcg de Picolinato de Cromo em exercício aeróbio (MCroEx). A glicemia plasmática foi monitorada a cada 15 minutos durante 75 minutos com o uso de um glicosímetro. O cromo gerou efeito positivo na captação de glicose, baixando significativamente os níveis plasmáticos, o que corrobora com alguns estudos, porém realizados com animais.  ABSTRACT Effects of the supplementation of chromium picolinate about the concentration of plasma glycemia during physical and rest exerciseChromium is an essential trace mineral absorbed from food, especially some foods such as meat and oil, and is mainly stored in the liver as the primary function having an increase in glucose tolerance associated with insulin in cell metabolism. The aim of this study was to investigate the effects of chromium picolinate in its version on blood glucose and how he handles the plasma glucose concentration in the body during exercise. Therefore, we used 17 healthy physically active individuals who participated in all phases of the experiment which was divided into four distinct phases, group supplemented with 50g of maltodextrin at rest (Malt), supplemented group with maltodextrin 50g in aerobic exercise (MEx), group supplemented with 50g of maltodextrin and 70 mcg of Chromium Picolinate at rest (MCro) and group supplemented with 50g of maltodextrin and 70 mcg of Chromium Picolinate in aerobic exercise (MCroEx). The plasma glucose was monitored every 15 minutes for 75 minutes using a glucometer. Chromium had a positive effect on glucose uptake, significantly lowering plasma levels, which corroborates some studies, though conducted on animals

It Takes Two to Tango, Part II : Synthesis of A-Ring Functionalised Quinones Containing Two Redox-Active Centres with Antitumour Activities

In 2021, our research group published the prominent anticancer activity achieved through the successful combination of two redox centres (ortho-quinone/para-quinone or quinone/seleniumcontaining triazole) through a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The combination of two naphthoquinoidal substrates towards a synergetic product was indicated, but not fully explored. Herein, we report the synthesis of 15 new quinone-based derivatives prepared from click chemistry reactions and their subsequent evaluation against nine cancer cell lines and the murine fibroblast line L929. Our strategy was based on the modification of the A-ring of paranaphthoquinones and subsequent conjugation with different ortho-quinoidal moieties. As anticipated, our study identified several compounds with IC50 values below 0.5 µM in tumour cell lines. Some of the compounds described here also exhibited an excellent selectivity index and low cytotoxicity on L929, the control cell line. The antitumour evaluation of the compounds separately and in their conjugated form proved that the activity is strongly enhanced in the derivatives containing two redox centres. Thus, our study confirms the efficiency of using A-ring functionalized para-quinones coupled with ortho-quinones to obtain a diverse range of two redox centre compounds with potential applications against cancer cell lines. Here as well, it literally takes two for an efficient tango

Activity of scorpion venom-derived antifungal peptides against planktonic cells of Candida spp. and Cryptococcus neoformans and Candida albicans Biofilms

The incidence of fungal infections has been increasing in the last decades, while the number of available antifungal classes remains the same. The natural and acquired resistance of some fungal species to available therapies, associated with the high toxicity of these drugs on the present scenario and makes an imperative of the search for new, more efficient and less toxic therapeutic choices. Antimicrobial peptides (AMPs) are a potential class of antimicrobial drugs consisting of evolutionarily conserved multifunctional molecules with both microbicidal and immunomodulatory properties being part of the innate immune response of diverse organisms. In this study, we evaluated 11 scorpion-venom derived non-disulfide-bridged peptides against Cryptococcus neoformans and Candida spp., which are important human pathogens. Seven of them, including two novel molecules, showed activity against both genera with minimum inhibitory concentration values ranging from 3.12 to 200 μM and an analogous activity against Candida albicans biofilms. Most of the peptides presented low hemolytic and cytotoxic activity against mammalian cells. Modifications in the primary peptide sequence, as revealed by in silico and circular dichroism analyses of the most promising peptides, underscored the importance of cationicity for their antimicrobial activity as well as the amphipathicity of these molecules and their tendency to form alpha helices. This is the first report of scorpion-derived AMPs against C. neoformans and our results underline the potential of scorpion venom as a source of antimicrobials. Further characterization of their mechanism of action, followed by molecular optimization to decrease their cytotoxicity and increase antimicrobial activity, is needed to fully clarify their real potential as antifungals