Tactile perception by friction induced vibrations

Cataloged from PDF version of article.When a finger moves to scan the surface of an object (haptic sensing), the sliding contact generates vibrations that propagate in the finger skin activating the receptors (mechanoreceptors) located in the skin, allowing the brain to identify objects and perceive information about their properties. The information about the surface of the object is transmitted through vibrations induced by friction between the skin and the object scanned by the fingertip. The mechanoreceptors transduce the stress state into electrical impulses that are conveyed to the brain. A clear understanding of the mechanisms of the tactile sensing is fundamental to numerous applications, like the development of artificial tactile sensors for intelligent prostheses or robotic assistants, and in ergonomics. While the correlation between surface roughness and tactile sensation has already been reported in literature, the vibration spectra induced by the finger-surface scanning and the consequent activation of the mechanoreceptors on the skin have received less attention. In this paper, frequency analysis of signals characterizing surface scanning is carried out to investigate the vibration spectrum measured on the finger and to highlight the changes shown in the vibration spectra as a function of characteristic contact parameters such as scanning speed, roughness and surface texture. An experimental set-up is developed to recover the vibration dynamics by detecting the contact force and the induced vibrations; the bench test has been designed to guarantee reproducibility of measurements at the low amplitude of the vibrations of interest, and to perform measurements without introducing external noise. Two different perception mechanisms, as a function of the roughness wavelength, have been pointed out. The spectrum of vibration obtained by scanning textiles has been investigated. (C) 2011 Elsevier Ltd. All rights reserved

AGROTÓXICOS: IMPACTOS AO MEIO AMBIENTE E À SAÚDE HUMANA

Com a expansão demográfica, aumentou-se a demanda na produção de alimentos e utilização intensa de defensivos agrícolas, visando o alto índice de produção.A exposição do homem aos agrotóxicos representa um grave problema de saúde pública.O Brasil é considerado o maior consumidor de agrotóxicos. Trata-se de uma revisão bibliográfica, com levantamento científico sobre o uso de agrotóxicos no Brasil, entre 1986 a 2017, utilizando descritores como agrotóxicos, saúde humana, Brasil e contaminação. Os trabalhadores rurais devem utilizar proteção básica diante da exposição aos agroquímicos e a técnica de pulverização aérea deve ser realizada e programada corretamente, para que o fenômeno da deriva seja minimizado, diminuindo a contaminação ambiental

Wild boar rooting intensity determines shifts in understorey composition and functional traits

In recent decades, the European populations of wild boar have grown substantially, as has the impact of this species, owing above all to its rooting activity. Our aim was to investigate the relationships between vascular plant understorey and wild boar rooting intensity. The questions we addressed are: does rooting intensity influence understorey species composition and diversity? Which functional traits are associated with different levels of rooting? We performed a comparative analysis of plant communities in areas with contrasting levels of rooting intensity within a Mediterranean deciduous lowland forest in central Italy. Besides comparing species composition and diversity, we tested the association between species traits and rooting levels through fourth-corner analysis. We found that contrasting levels of rooting were associated to different understorey species composition and evenness, while we observed no significant difference in species richness. In contrast with our expectations, sites with lower rooting returned i) lower evenness values and ii) a higher proportion of species characterized by traits related to resistance or response to herbivory, i.e., spinescence, clonality, endozoochory, underground storage organs, and low height values. Our findings suggest that current vegetation patterns partly depend on the legacy effect of past rooting disturbance, since the areas currently subjected to low rooting intensity were likely to be intensely rooted in the past. These areas may have developed a marked dominance of clonal thorny species that, in turn, inhibited further feeding activities by wild boar

A ADAPTAÇÃO DOS MONITORES AO PROGRAMA DE MONITORIA REMOTA DURANTE A PANDEMIA DE COVID-19

The COVID-19 pandemic has resulted in obstacles to medical education in Brazil. Classes were taught remotely, affecting the participation of monitors, since face-to-face contact was interrupted. This study aimed to analyze the adaptation of monitors regarding the assistance provided in class online. This is an exploratory-descriptive study, with a quantitative approach, with a cross-sectional approach using a data collection method. As a result, most students (49%) partially agreed on the good adaptation to remote monitoring during the COVID-19 pandemic. As for the speed of the adaptation process to remote monitoring, 45.1% partially agreed, a minority partially and totally disagreed, 5.7% and 9.8%, respectively. Remote activities presented a challenge for the academic community, despite this, most of the research students partially or fully agreed with the statement about the effectiveness and speed of the process of adaptation to remote monitoring.La pandemia de COVID-19 resultó en obstáculos para la educación médica en Brasil. Las clases se impartieron de forma remota, afectando la participación de los monitores, ya que se interrumpió el contacto cara a cara. Este estudio tuvo como objetivo analizar la adaptación de los monitores respecto a la asistencia prestada en clase de forma online. Se trata de un estudio exploratorio-descriptivo, con enfoque cuantitativo, con abordaje transversal a través de un método de recolección de datos. Como resultado, la mayoría de los estudiantes (49%) coincidieron parcialmente en una buena adaptación al monitoreo remoto durante la pandemia de COVID-19. En cuanto a la velocidad del proceso de adaptación a la monitorización remota, el 45,1% estuvo parcialmente de acuerdo, una minoría parcial y totalmente en desacuerdo, el 5,7% y el 9,8%, respectivamente. Las actividades remotas presentaron un desafío para la comunidad académica, aunque la mayoría de los estudiantes de la investigación coincidieron parcial o totalmente en la declaración sobre la efectividad y la velocidad del proceso de adaptación al monitoreo remoto.A pandemia de COVID-19 resultou em obstáculos para a educação médica no Brasil. Aulas foram ministradas remotamente, afetando a participação dos monitores, posto que o contato presencial foi interrompido. Este estudo teve como objetivo analisar a adaptação dos monitores quanto à assistência prestada em aula de forma online. Trata-se de um estudo exploratório-descritivo, de abordagem quantitativa, com recorte transversal por meio de método de levantamento de dados. Como resultados, a maioria dos estudantes (49%) concordou parcialmente sobre a boa adaptação à monitoria remota durante a pandemia do COVID-19. Quanto à rapidez do processo de adaptação à monitoria remota, 45,1% concordaram parcialmente, uma minoria discordou parcialmente e totalmente, 5,7% e 9,8%, respectivamente. As atividades remotas apresentaram um desafio para a comunidade acadêmica, apesar disso, grande parte dos estudantes da pesquisa concordou parcialmente ou plenamente a respeito da afirmativa sobre a efetividade e rapidez do processo de adaptação à monitoria remota

A ADAPTAÇÃO DOS MONITORES AO PROGRAMA DE MONITORIA REMOTA DURANTE A PANDEMIA DE COVID-19

The COVID-19 pandemic has resulted in obstacles to medical education in Brazil. Classes were taught remotely, affecting the participation of monitors, since face-to-face contact was interrupted. This study aimed to analyze the adaptation of monitors regarding the assistance provided in class online. This is an exploratory-descriptive study, with a quantitative approach, with a cross-sectional approach using a data collection method. As a result, most students (49%) partially agreed on the good adaptation to remote monitoring during the COVID-19 pandemic. As for the speed of the adaptation process to remote monitoring, 45.1% partially agreed, a minority partially and totally disagreed, 5.7% and 9.8%, respectively. Remote activities presented a challenge for the academic community, despite this, most of the research students partially or fully agreed with the statement about the effectiveness and speed of the process of adaptation to remote monitoring.La pandemia de COVID-19 resultó en obstáculos para la educación médica en Brasil. Las clases se impartieron de forma remota, afectando la participación de los monitores, ya que se interrumpió el contacto cara a cara. Este estudio tuvo como objetivo analizar la adaptación de los monitores respecto a la asistencia prestada en clase de forma online. Se trata de un estudio exploratorio-descriptivo, con enfoque cuantitativo, con abordaje transversal a través de un método de recolección de datos. Como resultado, la mayoría de los estudiantes (49%) coincidieron parcialmente en una buena adaptación al monitoreo remoto durante la pandemia de COVID-19. En cuanto a la velocidad del proceso de adaptación a la monitorización remota, el 45,1% estuvo parcialmente de acuerdo, una minoría parcial y totalmente en desacuerdo, el 5,7% y el 9,8%, respectivamente. Las actividades remotas presentaron un desafío para la comunidad académica, aunque la mayoría de los estudiantes de la investigación coincidieron parcial o totalmente en la declaración sobre la efectividad y la velocidad del proceso de adaptación al monitoreo remoto.A pandemia de COVID-19 resultou em obstáculos para a educação médica no Brasil. Aulas foram ministradas remotamente, afetando a participação dos monitores, posto que o contato presencial foi interrompido. Este estudo teve como objetivo analisar a adaptação dos monitores quanto à assistência prestada em aula de forma online. Trata-se de um estudo exploratório-descritivo, de abordagem quantitativa, com recorte transversal por meio de método de levantamento de dados. Como resultados, a maioria dos estudantes (49%) concordou parcialmente sobre a boa adaptação à monitoria remota durante a pandemia do COVID-19. Quanto à rapidez do processo de adaptação à monitoria remota, 45,1% concordaram parcialmente, uma minoria discordou parcialmente e totalmente, 5,7% e 9,8%, respectivamente. As atividades remotas apresentaram um desafio para a comunidade acadêmica, apesar disso, grande parte dos estudantes da pesquisa concordou parcialmente ou plenamente a respeito da afirmativa sobre a efetividade e rapidez do processo de adaptação à monitoria remota

Avaliação da cavidade nasal de camundongos submetidos à exposição ao herbicida ácido 2,4-diclorofenoxiacético

In the last year, Brazil presented a 190% increase in the use of agrochemicals, which implies a serious public health problem. 2,4-Dichlorophenoxyacetic acid has toxicological classification I (extremely toxic) and because it is very volatile, it favors the contamination of soils, water, animals and humans. Study model: Experimental study. Objective: To analyze the inflammatory infiltrate of mice submitted to acute nebulization to the 2.4-dichlorophenoxyacetic acid herbicide at different time intervals and concentrations. Methods: Eighty Swiss male mice were divided into four groups (n=20): saline, low (3.71 x 10-3 grams of active ingredient per hectare), medium (6.19 x 10-3 grams of active ingredient per hectare) and high concentration (9.28 x 10-3 grams of active ingredient per hectare). All animals were exposed to the nebulizations proposed for each group, for 15 minutes, at different time intervals: 24, 48, 72 and 192 hours. The exposure protocol had two boxes attached to an ultrasonic nebulizer and the nasal vestibule of each animal was removed after euthanasia for histological analysis. Results: The mast cell count showed significantly increased values in the high concentration group, in the time interval of 48 hours, when compared to the 24-hour period. Conclusion: The results showed that the acute exposure to the herbicide 2,4-dichlorophenoxyacetic acid increases the production of mast cells in the nasal cavity of animals exposed to high concentrations, which may be related to the appearance of allergic reactions.No último ano, o Brasil apresentou um aumento de 190% na utilização de agrotóxicos, o que implica em um grave problema de saúde pública. O ácido 2,4-diclorofenoxiacético possui classificação toxicológica I (extremamente tóxico) e por ser muito volátil, favorece a contaminação de solos, águas, animais e seres humanos. Modelo do estudo: Estudo Experimental. Objetivo: Analisar o infiltrado inflamatório de camundongos submetidos à nebulização aguda ao herbicida ácido 2,4-diclorofenoxiacético, em diferentes intervalos de tempo e concentrações. Métodos: Foram utilizados 80 camundongos Swiss machos divididos em quatro grupos (n=20): salina, baixa (3,71 x 10-3 gramas de ingrediente ativo por hectare), média (6,19 x 10-3 gramas de ingrediente ativo por hectare) e alta concentração (9,28 x10-3 gramas de ingrediente ativo por hectare). Todos os animais foram expostos às nebulizações preconizadas para cada grupo por 15 minutos, em diferentes intervalos de tempo: 24, 48, 72 e 192 horas. O protocolo de exposição contou com duas caixas ligadas a um nebulizador ultrassônico e o vestíbulo nasal de cada animal foi retirado após a eutanásia, para a análise histológica. Resultados: A contagem de mastócitos apresentou valores significativamente aumentados no grupo alta concentração, no intervalo de tempo de 48 horas, quando comparado ao de 24 horas. Conclusão: Os resultados mostraram que a exposição aguda ao herbicida ácido 2,4-diclorofenoxiacético aumenta a produção de mastócitos na cavidade nasal de animais expostos a altas concentrações, e que podem estar relacionados ao surgimento de reações alérgicas

Effects of Angiopoietin-2-Blocking Antibody on Endothelial Cell–Cell Junctions and Lung Metastasis

Background: Angiopoietin-2 (Ang2), a ligand for endothelial TEK (Tie2) tyrosine kinase receptor, is induced in hypoxic endothelial cells of tumors, where it promotes tumor angiogenesis and growth. However, the effects of Ang2 on tumor lymphangiogenesis and metastasis are poorly characterized. Methods: We addressed the effect of Ang2 on tumor progression and metastasis using systemic Ang2 overexpression in mice carrying tumor xenografts, endothelium-specific overexpression of Ang2 in VEC-tTA/Tet-OS-Ang2 transgenic mice implanted with isogenic tumors, and administration of Ang2-blocking antibodies to tumor-bearing immunodeficient mice. Fisher's exact test was used for analysis of metastasis occurrence, and repeated measures one-way analysis of variance was used for the analysis of primary tumor growth curves. Unpaired t test was used for all other analyses. All statistical tests were two-sided. Results: Adenoviral expression of Ang2 increased lymph node and lung metastasis in tumor xenografts. The metastatic burden in the lungs was increased in transgenic mice in which Ang2 expression was induced specifically in the vascular endothelium (tumor burden per grid, VEC-tTA/Tet-OS-Ang2 mice [n = 5] vs control mice [n = 4]: 45.23 vs 12.26 mm[superscript 2], difference = 32.67 mm[superscript 2], 95% confidence interval = 31.87 to 34.07, P < .001). Ang2-blocking antibodies reduced lymph node and lung metastasis, as well as tumor lymphangiogenesis, and decreased tumor cell homing to the lungs after intravenous injection. In the lung metastases, Ang2 overexpression decreased endothelial integrity, whereas the Ang2-blocking antibodies improved endothelial cell–cell junctions and basement membrane contacts of metastasis-associated lung capillaries. At the cellular level, the Ang2-blocking antibodies induced the internalization of Ang2-Tie2 receptor complexes from endothelial cell–cell junctions in endothelial–tumor cell cocultures. Conclusion: Our results indicate that blocking Ang2 inhibits metastatic dissemination in part by enhancing the integrity of endothelial cell–cell junctions

Skin tribology: Science friction?

The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is frequently one of the interacting surfaces in relative motion. People seem to solve these problems related to skin friction based upon a trial-and-error strategy and based upon on our sense for touch. The question of course rises whether or not a trained tribologist would make different choices based upon a science based strategy? In other words: Is skin friction part of the larger knowledge base that has been generated during the last decades by tribology research groups and which could be referred to as Science Friction? This paper discusses the specific nature of tribological systems that include the human skin and argues that the living nature of skin limits the use of conventional methods. Skin tribology requires in vivo, subject and anatomical location specific test methods. Current predictive friction models can only partially be applied to predict in vivo skin friction. The reason for this is found in limited understanding of the contact mechanics at the asperity level of product-skin interactions. A recently developed model gives the building blocks for enhanced understanding of friction at the micro scale. Only largely simplified power law based equations are currently available as general engineering tools. Finally, the need for friction control is illustrated by elaborating on the role of skin friction on discomfort and comfort. Surface texturing and polymer brush coatings are promising directions as they provide way and means to tailor friction in sliding contacts without the need of major changes to the produc