On cross-frequency phase-phase coupling between theta and gamma oscillations in the hippocampus

Phase-amplitude coupling between theta and multiple gamma sub-bands is a hallmark of hippocampal activity and believed to take part in information routing. More recently, theta and gamma oscillations were also reported to exhibit phase-phase coupling, or n:m phase-locking, suggesting an important mechanism of neuronal coding that has long received theoretical support. However, by analyzing simulated and actual LFPs, here we question the existence of theta-gamma phase-phase coupling in the rat hippocampus. We show that the quasi-linear phase shifts introduced by filtering lead to spurious coupling levels in both white noise and hippocampal LFPs, which highly depend on epoch length, and that significant coupling may be falsely detected when employing improper surrogate methods. We also show that waveform asymmetry and frequency harmonics may generate artifactual n:m phase-locking. Studies investigating phase-phase coupling should rely on appropriate statistical controls and be aware of confounding factors; otherwise, they could easily fall into analysis pitfalls

Influência dos substratos de polímero e alumínio na absorção de radiação eletromagnética apresentada por filmes finos de Ti

TCC (graduação) - Universidade Federal de Santa Catarina, Campus Joinville, Engenharia Aeroespacial.Os Materiais Absorvedores de Radiação Eletromagnética (MARE) são materiais que têm a capacidade de absorver a radiação eletromagnética incidente, através de mecanismos de perda intrínseca do material e fenômenos físicos relacionados as ondas eletromagnéticas. Esses materiais são amplamente utilizados para resolver problemas relacionados à interferência e compatibilidade eletromagnética. Sua utilização é ampla em setores como o aeroespacial, defesa militar, médico e automotivo. No setor aeroespacial, os MAREs são empregados no desenvolvimento de tecnologias de redução de detecção, tornando as aeronaves menos visíveis aos radares em faixas de frequência específicas. Na concepção de aeronaves, a utilização de materiais leves e facilmente moldáveis é crucial devido às restrições de peso e necessidade de manobrabilidade. Nesse contexto, os filmes finos metálicos se apresentam como uma solução tecnológica, uma vez que possuem baixa densidade e espessuras na ordem de dezenas de nanômetros. Neste estudo, foram avaliadas as propriedades absorvedoras de radiação eletromagnética de filmes finos de Titânio (Ti) depositados sobre dois tipos de substrato: polímero (Polietileno Tereftalato (PET)) e Alumínio (Al). Os resultados mostraram atenuações de até 95% para os filmes de Ti sobre substratos de polímero e de cerca de 40%-50% para os filmes finos de Ti depositado sobre substratos de Al. A análise também investigou a influência de características da morfologia da superfície, resistividade elétrica e espessura dos filmes na eficiência da atenuação da radiação, demonstrando que a escolha do substrato pode alterar o desempenho de absorção.Radar Absorbing Materials (RAMs) are materials capable of absorbing incident electromagnetic radiation through intrinsic material loss mechanisms and physical phenomena related to electromagnetic waves. These materials are widely used to solve problems related to electromagnetic interference and compatibility. Their use extends to sectors such as aerospace, military defense, medical, and automotive. In the aerospace sector, RAMs are employed in the development of detection reduction technologies, making aircraft less visible to radars within specific frequency ranges. In aircraft design, the use of lightweight and easily moldable materials is crucial due to weight restrictions and the need for maneuverability. In this context, metallic thin films are presented as a technological solution, since they have low density and thicknesses on the order of tens of nanometers. In this study, the electromagnetic radiation absorbing properties of Titanium (Ti) thin films deposited on two types of substrates: polymer (Polyethylene Terephthalate (PET)) and Aluminium (Al). The results showed attenuation levels of up to 95% for Ti films on polymer substrates and approximately 40%-50% for Ti thin films deposited on Al substrates. The analysis also investigated the influence of surface morphology characteristics, electrical resistivity, and film thickness on radiation attenuation efficiency, demonstrating that the choice of substrate can affect absorption performance

Multi-Particle Collision Dynamics -- a Particle-Based Mesoscale Simulation Approach to the Hydrodynamics of Complex Fluids

In this review, we describe and analyze a mesoscale simulation method for fluid flow, which was introduced by Malevanets and Kapral in 1999, and is now called multi-particle collision dynamics (MPC) or stochastic rotation dynamics (SRD). The method consists of alternating streaming and collision steps in an ensemble of point particles. The multi-particle collisions are performed by grouping particles in collision cells, and mass, momentum, and energy are locally conserved. This simulation technique captures both full hydrodynamic interactions and thermal fluctuations. The first part of the review begins with a description of several widely used MPC algorithms and then discusses important features of the original SRD algorithm and frequently used variations. Two complementary approaches for deriving the hydrodynamic equations and evaluating the transport coefficients are reviewed. It is then shown how MPC algorithms can be generalized to model non-ideal fluids, and binary mixtures with a consolute point. The importance of angular-momentum conservation for systems like phase-separated liquids with different viscosities is discussed. The second part of the review describes a number of recent applications of MPC algorithms to study colloid and polymer dynamics, the behavior of vesicles and cells in hydrodynamic flows, and the dynamics of viscoelastic fluids

Theta-phase modulates different high-frequency oscillations in the CA1 region of the hippocampus during both waking and rapid-eye movement sleep.

Recent evidence suggests that not only the brain rhythms per se, but also the interactions among them are involved in the execution of cognitive tasks, mainly those requiring selective attention, information transmission and memory consolidation. However, still little is known about the general characteristics of cross-frequency coupling (CFC) in several brain regions. In the present work, we aimed to characterize phase-amplitude CFC in the CA1 region of rats (n=9) during different stages of the sleep-wake cycle: wake (WK), slow-wave sleep (SWS), and rapid-eye movement sleep (REM). Local field potentials were recorded using multielectrode arrays implanted in the dorsal hippocampus for chronic neural recordings. Electrode positioning was verified by histological analysis of cresyl-stained brain sections. Phase-amplitude coupling was assessed by means of the comodulogram analysis, a CFC tool we have recently developed. Our results show that (1) each sleep-wake state contains characteristic patterns of phase-amplitude CFC that are robust across all animals studied. (2) The CFC patterns obtained during WK and REM are similar and characterized by theta-phase (5 – 10 Hz) modulation of multiple higher frequencies; on the other hand, comodulograms from SWS period exhibited a distinct pattern, characterized by the modulation of very fast oscillations (> 100 Hz) by delta-phase (0 – 4 Hz), consistent with the occurrence of sharp wave-ripple complexes. All these patterns were stable across electrodes and days. Interestingly, during WK and REM, our results indicate that (3) theta-phase modulation comprises two non-overlapping, circumscribed higher frequency ranges: oscillations in the high-gamma (HG, 60 – 100 Hz) frequency range and oscillations between 120 – 160 Hz, which were defined as high-frequency oscillations (HFO). Moreover, (4) theta-phase preferentially modulated more HG or HFO depending on the spatial position of the electrode, with a clear switching between one and another as a function of electrode location, which was also stable across days. Further analyses indicated that (5) electrodes exhibiting HG or HFO modulation during WK and REM can also be differentiated by other electrophysiological features, such as power spectrum, phase-relations, and SWS comodulograms. We argue that the HFO we observed, though presenting overlapping frequency range with ripple oscillations, are distinct from the latter, which only appear in periods of rest and sleep associated to sharp-wave complexes. Therefore, while characterizing the patterns of rhythmic interactions in different cognitive states, the present work also reveals novel hippocampal oscillations that could only be detected by the use of the new CFC tools. We speculate that the different amplitude-modulated bands correspond to different biophysical processes occurring in CA1: HFO would result from entorhinal synaptic inputs to CA1, and HG from CA3 inputs

Fundamentos e tendências da formação profissional na escola de serviço social de Porto Alegre (1945-1954)

O presente artigo busca revisitar a história da Escola de Serviço Social de Porto Alegre, tendo como finalidade analisar os elementos que compunham os fundamentos da profissão no início de sua institucionalização. Tem como enfoque o período de 1945 a 1954, buscando caracterizar a formação profissional, averiguando as perspectivas teórico-filosóficas que influenciavam esse processo, a partir do contexto social brasileiro e internacional, acentuando as particularidades regionais. Para tanto, a pesquisa está concentrada no resgate de documentos históricos da Escola, como o ementário das disciplinas ofertadas na época, assim como os trabalhos de conclusão defendidos pelos primeiros profissionais formados e que posteriormente tornaram-se figuras protagonistas na condução da Escola

Social work reconception and Latin American seminars : analysis of the participation of the Porto Alegre school

Esse artigo é fruto da terceira etapa da pesquisa “O Movimento de Reconceituação Latino-americano na Escola de Serviço Social de Porto Alegre”, que visa identificar as bases do debate latino-americano nesta escola. Para tanto, foi desenvolvido um estudo exploratório com entrevistas, consultas a artigos, livros e documentos históricos a fim de caracterizar a expressão de tendência reconceituadora na Escola de Porto Alegre, assim como sua repercussão no Movimento de Reconceituação na América Latina. O artigo tem como fio condutor os seminários latino-americanos de Serviço Social e a participação dos professores gaúchos nesses eventos. Destaca-se também a trajetória de Seno Cornely, na época professor da Escola de Serviço Social de Porto Alegre (ESS-POA), por seu protagonismo no Movimento de Reconceituação e sua intensa participação na articulação profissional na América Latina.This article is the result of the third stage of the research "The Movement of Latin American Reconceptualization in the School of Social Work of Porto Alegre", which aims to identify the bases of the Latin American debate in this school. In order to do so, an exploratory study was conducted with interviews, consultations in articles, books and historical documents in order to characterize the expression of a reconceptualizing tendency in the School of Porto Alegre, as well as its repercussion inthe Movement of Reconceptualization in Latin America. The article has as its guiding principle the Latin American seminars on Social Work and the participation of gaucho professors in these events. Also noteworthy is the trajectory of Seno Cornely, professor of the School of Social Work of Porto Alegre at the time, for his role in the Movement of Reconceptualization and his intense participation in professional articulation in Latin America

The Latin American reconceptualization in the Brazilian dictatorship : the renewal of the social work in the state of Rio Grande do Sul

O artigo é fruto de pesquisa sobre o Movimento de Reconceituação Latino-Americano na Escola de Serviço Social de Porto Alegre. Discute a renovação do Serviço Social gaúcho no período ditatorial, evidenciando a constituição da vertente profissional denominada de “Reformismo Reconceituador”. Aborda a caracterização dessa vertente, a qual incidiu na articulação do Movimento de Reconceituação, a partir da realização do I Seminário Latino-Americano em Porto Alegre (1965).The article is the result of research on the Latin American Reconciliation Movement in the School of Social Work of Porto Alegre. It discusses the renewal of the Gaucho Social Work in the dictatorial period, evidencing the constitution of the professional strand denominated as “Reconceptual Reformism”. It addresses the characterization of this strand, which has affected the articulation of the Reconciliation Movement, starting from the I Latin American Seminar in Porto Alegre (1965)

Antecedentes da Reconceituação Latino-Americana na Escola de Porto Alegre-RS = Latin American Reconceptualization Antecedents in the School of Porto Alegre-RS

Este artigo apresenta resultados da pesquisa “Serviço Social, memória e reconceituação latino-americana: antecedentes e expressões na escola de Porto Alegre – RS”. A metodologia utilizada foi a análise documental do acervo histórico da escola, englobando currículos, planos de disciplinas e categorização de 517 trabalhos de conclusão de curso, no período de 1948 a 1975. Pelos resultados, verifica-se que a influência do desenvolvimentismo na escola foi impulsionada pela realização de Seminários Internacionais em Porto Alegre, na década de 1950, intensificada no início da década de 1960, no quadro da conjuntura política do governo Leonel Brizola. No período que antecede a realização do I Seminário Latino-Americano de 1965, sediado nesta escola, verificam-se duas tendências de renovação profissional: estrutural-participativa, articulada pelo docente Seno Cornely, com influência do pensamento cepalino, da técnica de Seminários na mobilização de comunidades, integrando DC, planejamento e política social no âmbito do Departamento de Assistência Social; e pedagógico-cultural, vinculada ao movimento de Cultura Popular, articulada pelas docentes Lucia Castillo e Zilah Totta sob a influência da esquerda católica, articulada com a Secretaria de Cultura, e influência intelectual de Ernani Fior