A Markovian dynamics for Caenorhabditis elegans behavior across scales.

How do we capture the breadth of behavior in animal movement, from rapid body twitches to aging? Using high-resolution videos of the nematode worm Caenorhabditis elegans, we show that a single dynamics connects posture-scale fluctuations with trajectory diffusion and longer-lived behavioral states. We take short posture sequences as an instantaneous behavioral measure, fixing the sequence length for maximal prediction. Within the space of posture sequences, we construct a fine-scale, maximum entropy partition so that transitions among microstates define a high-fidelity Markov model, which we also use as a means of principled coarse-graining. We translate these dynamics into movement using resistive force theory, capturing the statistical properties of foraging trajectories. Predictive across scales, we leverage the longest-lived eigenvectors of the inferred Markov chain to perform a top-down subdivision of the worm's foraging behavior, revealing both "runs-and-pirouettes" as well as previously uncharacterized finer-scale behaviors. We use our model to investigate the relevance of these fine-scale behaviors for foraging success, recovering a trade-off between local and global search strategies.

Towards accurate monitoring of water content in woody tissue across tropical forests and other biomes.

Forest ecosystems face increasing drought exposure due to climate change, necessitating accurate measurements of vegetation water content to assess drought stress and tree mortality risks. Although Frequency Domain Reflectometry offers a viable method for monitoring stem water content by measuring dielectric permittivity, challenges arise from uncertainties in sensor calibration linked to wood properties and species variability, impeding its wider usage. We sampled tropical forest trees and palms in eastern Amazônia to evaluate how sensor output differences are controlled by wood density, temperature and taxonomic identity. Three individuals per species were felled and cut into segments within a diverse dataset comprising five dicotyledonous tree and three monocotyledonous palm species on a wide range of wood densities. Water content was estimated gravimetrically for each segment using a temporally explicit wet-up/dry-down approach and the relationship with the dielectric permittivity was examined. Woody tissue density had no significant impact on the calibration, but species identity and temperature significantly affected sensor readings. The temperature artefact was quantitatively important at large temperature differences, which may have led to significant bias of daily and seasonal water content dynamics in previous studies. We established the first tropical tree and palm calibration equation which performed well for estimating water content. Notably, we demonstrated that the sensitivity remained consistent across species, enabling the creation of a simplified one-slope calibration for accurate, species-independent measurements of relative water content. Our one-slope calibration serves as a general, species-independent standard calibration for assessing relative water content in woody tissue, offering a valuable tool for quantifying drought responses and stress in trees and forest ecosystems.

Dependência química pelo crack: vivências e percepções dos discentes do internato de um curso médico / Chemical dependence on crack: experiences and perceptions of internship students of a medical school

Modelo de estudo: Estudo transversal e qualitativo. Objetivos: Este trabalho investiga as vivências e identifica as percepções dos discentes do internato do nono período de medicina de uma universidade pública, sobre dependência química pelo crack. Metodologia: Estudo transversal de abordagem qualitativa, cujo instrumento da pesquisa foi uma entrevista individual, utilizando-se um roteiro semiestruturado, que permite amplo discurso dos discentes. As falas das gravações foram transcritas e depois realizada a análise do conteúdo segundo Bardin. Resultados: Foram identificadas categorias referentes ao sentimento da vivência, à percepção do discente sobre a dependência do crack e seu aprendizado sobre o tema, aos comprometimentos físicos, aos outros prejuízos causados e a como a sociedade deve lidar diante da dependência química pelo crack. Os sentimentos de compaixão e de preservação estão presentes em suas vivências. Os discentes relacionam as questões econômicas, profissionais e familiares como fontes das graves consequências do crack. Valorizam os prejuízos sociais e existenciais, a autodestruição, a violência e o emagrecimento que o crack causa aos usuários, além da codependência. É grande a preocupação dos discentes com a prevenção, educação, informação, eliminação do preconceito e cobranças de ações governamentais para combate ao crack. Conclusão: Os discentes do internato consideram a dependência química pelo crack como problema social e doença.Definem como insuficiente o aprendizado sobre a dependência química pelo crack durante o curso. Suas vivências e percepções geram impactos positivos, pois apontam para futuros egressos melhor preparados, que deverão acolher o dependente e sua família de forma mais ampla, humana e eficaz.

Study design: Cross-sectional and qualitative study. Objectives: This study investigates experiences and identifies the perceptions of ninth-term intern medical students of a public university on the crack addiction issue. Methods: A qualitative-approach and cross-sectional study which had as the research tool a semi-structured, individual interview allowing broad speech of students. Recording reports were transcribed and content analysis carried out according to Bardin. Results: categories were identified concerning the feeling of experience, the students’ perception on crack addiction and their learning on the subject, physical impairments and additional damages, besides how society should deal with the addiction on crack. The feelings of compassion and preservation are present in their experiences. Students point out economic, professional and family issues as the sources of serious crack addiction consequences. They also take into account the social and existential damages, the self-destruction, violence and weight loss caused on crack users, as well as the codependency. There is a great concernon the part of students related to prevention, education, information, elimination of prejudice, as well as demands of government efforts to combat crack. Conclusion: The intern medical students consider crack addiction both a social problem and a disease; define learning about addiction by crack insufficient throughout the course. Their experiences and perceptions generate positive impacts since they prospect better prepared graduates who shall receive the one addicted and his family in a broader, more effective and humane way.

Intratemporal facial nerve grafting: a simplified effective technique

Os autores apresentam uma técnica cirúrgica para enxerto do nervo facial em suas porçöes horizontal e vertical, no osso temporal, que dispensa o uso de suturas ou cola biológica, e documentam os resultados com 2 casos operados há 11 anos (caso 1) e 1 ano (caso 2)