The onset of chaos in orbital pilot-wave dynamics

We present the results of a numerical investigation of the emergence of chaos in the orbital dynamics of droplets walking on a vertically vibrating fluid bath and acted upon by one of the three different external forces, specifically, Coriolis, Coulomb, or linear spring forces. As the vibrational forcing of the bath is increased progressively, circular orbits destabilize into wobbling orbits and eventually chaotic trajectories. We demonstrate that the route to chaos depends on the form of the external force. When acted upon by Coriolis or Coulomb forces, the droplet's orbital motion becomes chaotic through a period-doubling cascade. In the presence of a central harmonic potential, the transition to chaos follows a path reminiscent of the Ruelle-Takens-Newhouse scenario

Hydrodynamic analog of particle trapping with the Talbot effect

We present the results of an experimental study of the standing waves produced on the surface of a vertically shaken fluid bath just above the Faraday threshold, when a row of equally spaced pillars protrudes from the surface. When the pillar spacing is twice the Faraday wavelength, the resulting wave field is marked by images of the pillars projected at integer multiples of a fixed distance from the row. This projection effect is shown to be analogous to the well-known Talbot or self-imaging effect in optics, and a Faraday-Talbot length is defined that rationalizes the location of the images. A simple model of point sources emitting circular waves captures the observed patterns. We demonstrate that the images may serve as traps for bouncing and walking droplets.National Science Foundation (U.S.) (Grant CMMI-1333242)National Science Foundation (U.S.) (Grant DMS-1614043)Natioanal Science Foundation (U.S.) (Grant CMMI-1727565

CONTRATOS INTELIGENTES NA BLOCKCHAIN: VALIDADE E RESTRIÇÕES

Esse estudo analisa a natureza e as implicações jurídicas dos contratos inteligentes (smart contracts) autoexecutáveis disponíveis na blockchain. Da leitura de suas características, constata-se que o contrato inteligente na blockchain é um algoritmo jurídico que proporciona uma eficiência contratual inédita por meio da ininterrupção e irreversibilidade dos ajustes contratuais programados. Apesar de já existirem estudos que intentem flexibilizar o conteúdo desses contratos, essa modalidade rompe com os paradigmas da teoria contratual na qual se assentam as relações jurídicas essencialmente analógicas. Assim, a partir de um método hipotético-dedutivo, se pretende delinear os contornos do que seria um contrato inteligente, seu âmbito de aplicação e apontar algumas possíveis restrições

Effects of a novel calcium aluminate cement on the early events of the progression of osteogenic cell cultures

The present study evaluated the progression of osteogenic cell cultures exposed to a novel calcium aluminate cement (CAC+) in comparison with the gold standard mineral trioxide aggregate (MTA). Cells were enzimatically isolated from newborn rat calvarial bone, plated on glass coverslips containing either CAC+ or a control MTA samples in the center, and grown under standard osteogenic conditions. Over the 10-day culture period, roundening of sample edges was clearly noticed only for MTA group. Although both cements supported osteogenic cell adhesion, spreading, and proliferation, CAC+-exposed cultures showed significantly higher values in terms of total cell number at days 3 and 7, and total protein content and alkaline phosphatase activity at day 10. The present in vitro results indicate that the exposure to CAC+ supports a higher differentiation of osteogenic cells compared with the ones exposed to MTA. Further experimental studies should consider CAC+ as a potential alternative to MTA when the repair of mineralized tissues is one of the desired outcomes in endodontic therapy.O objetivo do presente estudo foi avaliar a progressão de cultura de células osteogênicas expostas a um novo cimento de aluminato de cálcio (CAC+) em comparação ao agregado de trióxido mineral (MTA). As células foram obtidas por digestão enzimática de calvária de ratos recém-nascidos, plaqueadas sobre lamínulas de vidro contendo em sua área central discos de CAC+ ou MTA e crescidas em condições osteogênicas por até 10 dias. Durante a cultura primária, observou-se o arredondamento das bordas das amostras de cimento apenas para MTA. Embora ambos os cimentos tenham permitido a adesão, o espraiamento e a proliferação celulares, as culturas crescidas em contato com CAC+ exibiram valores maiores de número total de células em 3 e 7 dias, e de conteúdo de proteína total e atividade de fosfatase alcalina em 10 dias. Os resultados indicam que a exposição ao CAC+ permite o desenvolvimento de uma proporção maior de células em estágios mais avançados da diferenciação osteoblástica, quando comparado ao MTA. Deve-se considerar em futuros estudos experimentais a utilização do CAC+ como um material alternativo ao MTA especialmente quando um dos objetivos do tratamento endodôntico é o de reparação dos tecidos mineralizados da região periapical.(FAPESP) São Paulo Research Foundation(CNPq) National Council of Scientific and Technological Developmen

Biopolymer-based membranes associated with osteogenic growth peptide for guided bone regeneration

Barrier membranes for guided bone regeneration (GBR) mainly promote mechanical maintenance of bone defect space and induce osteopromotion. Additionally, biopolymer-based membranes may provide greater bioactivity and biocompatibility due to their similarity to extracellular matrix (ECM).In this study, biopolymers-based membranes from bacterial cellulose (BC) and collagen (COL) associated with osteogenic growth peptide (OGP(10–14)) were evaluated to determine in vitro osteoinductive potential in early osteogenesis; moreover, histological study was performed to evaluate the BC–COL OGP(10–14) membranes on bone healing after GBR in noncritical defects in rat femur. The results showed that the BC–COL and BC–COL OGP(10–14) membranes promoted cell proliferation and alkaline phosphatase activity in osteoblastic cell cultures. However, ECMmineralization was similar between cultures grown on BC OGP(10–14) and BC–COL OGP(10–14) membranes. In vivo results showed that all the membranes tested, including the peptide-free BC membrane, promoted better bone regeneration than control group. Furthermore, the BC–COL OGP(10–14) membranes induced higher radiographic density in the repaired bone than the other groups at 1, 4 and 16 weeks. Histomorpho-metric analyses revealed that the BC–COL OGP(10–14) induced higher percentage of bone tissue in the repaired area at 2 and 4 weeks than others membranes. In general, these biopolymer-based membranes might be potential candidates for bone regeneration applications

Bacterial cellulose-collagen nanocomposite for bone tissue engineering

A nanocomposite based on bacterial cellulose (BC) and type I collagen (COL) was evaluated for in vitro bone regeneration. BC membranes were modified by glycine esterification followed by cross-linking of type I collagen employing 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide. Collagen incorporation was studied by spectroscopy analysis. X-Ray diffraction showed changes in the BC crystallinity after collagen incorporation. The elastic modulus and tensile strength for BC-COL decreased, while the strain at failure showed a slight increase, even after sterilization, as compared to pristine BC. Swelling tests and contact angle measurements were also performed. Cell culture experiments performed with osteogenic cells were obtained by enzymatic digestion of newborn rat calvarium revealed similar features of cell morphology for cultures grown on both membranes. Cell viability/proliferation was not different between BC and BC-COL membranes at day 10 and 14. The high total protein content and ALP activity at day 17 in cells cultured on BC-COL indicate that this composite allowed the development of the osteoblastic phenotype in vitro. Thus, BC-COL should be considered as alternative biomaterial for bone tissue engineering.FAPESP [08-58776-6, 09/09960-1]FAPESPCNPqCNP

What is the frequency of floor of the mouth lesions? A descritive study of 4,016 cases

The aim of this study was to investigate the frequency of oral lesions in the floor of the mouth from representative oral pathology centres in Latin America. This study was conducted on biopsies obtained from January of 1978 to December of 2018 at nine Latin America oral and maxillofacial pathology centres. Gender, age and histopathological diagnosis were evaluated. Data were analysed using descriptive methods. Chi-square test was used for pairwise comparisons. From 114,893 samples, 4,016 lesions (3.49%) occurred in the floor of the mouth. Brazil showed 3,777 cases (94%), Mexico 182 cases (4.5%) and Argentina 57 cases (1.4%). Benign lesions represented 65.1% (2,617 cases), followed by 34.9% (1,404 cases) of malignant disorders. Lesions of epithelial origin were more frequent (1,964 cases; 48.9%), followed by salivary glands (1,245 cases; 31%) and soft tissue lesions (475 cases; 11.7%). The most common histological subtypes were oral squamous cell carcinoma (1,347 cases; 33.5%), ranula (724 cases; 18%), oral leukoplakia (476 cases; 11.8%) and inflammatory fibrous hyperplasia (239 cases; 5.9%). The lesion affected males in 2,129 cases and females in 1,897 cases. In the current study, lesions in the floor of the mouth represented 3.49% of biopsies submitted to oral pathology services and oral squamous cell carcinoma, ranula and leukoplakia were the most common lesions

Importância da angioplastia no tratamento do infarto agudo do miocárdio com supradesnivelamento do segmento ST

Introdução: A angioplastia é um procedimento médico de extrema importância no tratamento do infarto agudo do miocárdio com supradesnivelamento do segmento ST. Também conhecido como IAM com supra ST, esse tipo de infarto é caracterizado por uma obstrução grave e prolongada das artérias coronárias, que são responsáveis por fornecer sangue ao músculo cardíaco. Métodos: Trata-se de uma revisão integrativa da literatura por proporcionar uma síntese dos resultados obtidos através de pesquisas publicadas. Para direcionar a pesquisa, adotou-se como pergunta norteadora: “Qual é o papel da angioplastia e a sua importância no tratamento do infarto agudo do miocárdio com supradesnivelamento do segmento ST?”. Para construção da pesquisa, a coleta e análise de dados foram realizadas através do Portal da Biblioteca Virtual da Saúde, da base de dados Medical Literature Analysis and Retrievel System Online via PubMed e do Google Acadêmico através dos Descritores em Ciências da Saúde (DeCS): “Infarto do Miocárdio”, “Angioplastia”, “Reperfusão Miocárdica” combinados entre si pelo operador booleano AND. Resultados e Discussão: Após o cumprimento dos procedimentos metodológicos, 12 artigos disponíveis no portal da BVS, na plataforma PubMed e no Google Scholar foram selecionados, os quais evidenciaram que a angioplastia é um procedimento essencial no tratamento do infarto agudo do miocárdio com supradesnivelamento do segmento ST. Conclusão: A angioplastia é um procedimento minimamente invasivo que consiste na inserção de um cateter especializado para desobstruir as artérias coronárias bloqueadas. Essa técnica permite restaurar o fluxo sanguíneo para o músculo cardíaco, reduzindo a área de necrose e melhorando a sobrevida dos pacientes

Walking droplets confined by applied or topographically-induced potentials : dynamics and stability

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mathematics, 2018.Cataloged from PDF version of thesis.Includes bibliographical references (pages 121-129).In 2005, Yves Couder and coworkers discovered that a millimetric droplet of silicone oil may walk on the surface of a vertically-vibrating fluid bath, displaying features that were once thought to be peculiar to quantum mechanics. We here explore this hydrodynamic pilot-wave system through an integrated theoretical and experimental approach. We provide a theoretical characterization of the transition to chaos in orbital pilot-wave dynamics for droplets walking in the presence of a Coulomb, Coriolis, or central harmonic force. We proceed by investigating this hydrodynamic system above the Faraday threshold experimentally, with an aim of finding mechanisms to trap drops. We report a hydrodynamic analog of optical trapping with the Talbot effect, showing that drops may become trapped at the extrema of waves generated in the vicinity of a linear array of pillars. We also characterize the dynamics of droplets bouncing and walking above the Faraday threshold, indicating regimes of particle trapping and Brownian motion. We investigate the effect of bath topography in drop dynamics by considering a circular well that induces a circularly-symmetric Faraday wave pattern. In this regime, we show that droplets become trapped into stable circular orbits around the extrema of the well-induced wavefield. Finally, with a view to extending the phenomenological range of this hydrodynamic system, we consider a generalized pilot-wave framework, in which the relative magnitudes of dynamical parameters are altered relative to those relevant in the fluid system. In this generalized framework, we validate the theoretical result of Durey et al. relating the particle's mean wavefield to the emerging statistics, and characterizing the timescale of emergence of the statistically steady state for the chaotic pilot-wave dynamics.by Lucas Dorigo Tambasco.Ph. D

Exploring orbital dynamics and trapping with a generalized pilot-wave framework

We explore the effects of an imposed potential with both oscillatory and quadratic components on the dynamics of walking droplets. We first conduct an experimental investigation of droplets walking on a bath with a central circular well. The well acts as a source of Faraday waves, which may trap walking droplets on circular orbits. The observed orbits are stable and quantized, with preferred radii aligning with the extrema of the well-induced Faraday wave pattern. We use the stroboscopic model of Oza et al. [J. Fluid Mech. 737, 552-570 (2013)] with an added potential to examine the interaction of the droplet with the underlying well-induced wavefield. We show that all quantized orbits are stable for low vibrational accelerations. Smaller orbits may become unstable at higher forcing accelerations and transition to chaos through a path reminiscent of the Ruelle-Takens-Newhouse scenario. We proceed by considering a generalized pilot-wave system in which the relative magnitudes of the pilot-wave force and drop inertia may be tuned. When the drop inertia is dominated by the pilot-wave force, all circular orbits may become unstable, with the drop chaotically switching between them. In this chaotic regime, the statistically stationary probability distribution of the drop's position reflects the relative instability of the unstable circular orbits. We compute the mean wavefield from a chaotic trajectory and confirm its predicted relationship with the particle's probability density function.National Science Foundation (Grant DMS-1614043)National Science Foundation (Grant CMMI-1727565