Hydrodynamic flow patterns and synchronization of beating cilia

We calculate the hydrodynamic flow field generated far from a cilium which is attached to a surface and beats periodically. In the case of two beating cilia, hydrodynamic interactions can lead to synchronization of the cilia, which are nonlinear oscillators. We present a state diagram where synchronized states occur as a function of distance of cilia and the relative orientation of their beat. Synchronized states occur with different relative phases. In addition, asynchronous solutions exist. Our work could be relevant for the synchronized motion of cilia generating hydrodynamic flows on the surface of cells.Comment: 5 pages, 4 figures, v2: minor correction

BUCA Inktober Zine 2016

Boston University Comic Arts is a student-run organization that brings together comic artists and illustrators of all backgrounds and skill levels. We meet twice weekly to share our work with each other, draw together, and learn together. Our goal is to provide learning and networking opportunities for our members as well as to introduce the world of comics to the Boston University community!During the month of October, artists around the world participate in Inktober, an event which challenges artists to create an illustration using ink every day for the month of October. This zine features some of the illustrations created by our club members for Inktober 2016

The Corbusier Dream and Frank Lloyd Wright Vision: Cliff Detritus Vs. Urban Savanna

Investigators are seeking methods to assess the visual and environmental quality of the landscape across urban areas. In addition investigators are interested in applying these predictors to study landscape transformation and change. In our study we employed an environmental quality prediction equation, which assesses environmental quality to create a visual quality map of southern Michigan and then evaluated the map’s ability to determine the map’s reliability. Through the Kendall’s coefficient of concordance statistical test, we determined that the map is significantly reliable (p ≤ 0.01) and conclude that constructing such a map of a large area is possible. We then applied this approach to quantify environmental quality change to southeast Michigan (Detroit metropolitan area) from land-use maps in the 1800s, and from a map constructed in 2008. Only areas with cliff detritus had statistically significant changes. Many of these cliff detritus areas are now being transformed back to pastoral urban savanna environments, a vision that had been embraced by Frank Lloyd Wright. Wright’s approach compares differently with the grand vision Le Corbusier had for urban areas, a series of multiple-use towers spaced across an urban forest. The sprawling towers of Shanghai, P.R. of China exemplify this model in a modern manner

BUCA Inktober Zine

Boston University Comic Arts is a student-run organization that brings together comic artists and illustrators of all backgrounds and skill levels. We meet twice weekly to share our work with each other, draw together, and learn together. Our goal is to provide learning and networking opportunities for our members as well as to introduce the world of comics to the Boston University community

Flagellar Synchronization Through Direct Hydrodynamic Interactions

Microscale fluid flows generated by ensembles of beating eukaryotic flagella are crucial to fundamental processes such as development, motility and sensing. Despite significant experimental and theoretical progress, the underlying physical mechanisms behind this striking coordination remain unclear. Here, we present a novel series of experiments in which the flagellar dynamics of two micropipette-held somatic cells of Volvox carteri, with measurably different intrinsic beating frequencies, are studied by high-speed imaging as a function of their mutual separation and orientation. From analysis of beating time series we find that the interflagellar coupling, which is constrained by the lack of chemical and mechanical connections between the cells to be purely hydrodynamical, exhibits a spatial dependence that is consistent with theoretical predictions. At close spacings it produces robust synchrony which can prevail for thousands of flagellar beats, while at increasing separations this synchrony is systematically degraded by stochastic processes. Manipulation of the relative flagellar orientation reveals the existence of both in-phase and antiphase synchronized states, which is consistent with dynamical theories. Through dynamic flagellar tracking with exquisite spatio-temporal precision, we quantify changes in beating waveforms that result from altered coupling configuration and distance of separation. The experimental results of this study prove unequivocally that flagella coupled solely through a fluid medium can achieve robust synchrony despite significant differences in their intrinsic properties.Comment: 23 pages, 13 figure

“Triplets of Different Ages”: the experience of motherhood through the adoption of siblings

A experiência da maternidade por adoção de um grupo de irmãos pode se configurar como um desafio no pós-adoção, mas a literatura sobre o assunto é escassa. Pensando nisso, o objetivo do presente estudo foi compreender como se construiu a relação mãe-filhos, em um caso de adoção de grupo de irmãos, ao longo de dez sessões de psicoterapia de referencial teórico psicanalítico e da teoria do apego. Utilizou-se a Análise Temática nas transcrições das sessões para buscar aspectos específicos da adaptação mãe-três filhos e identificar padrões de temas e subtemas. Os resultados ressaltaram um período de idealização dos filhos mais novos, sustentado por dificuldades na adaptação com o filho mais velho. Essas dificuldades iniciais foram superadas na medida em que a mãe pode ver com os filhos mais novos de forma menos idealizada e pode construir uma identificação com o mais velho. Foi necessário um período de intensa disponibilidade emocional materna às necessidades individualizadas dos seus três filhos, como se fossem trigêmeos de idades diferentes. Ressaltou-se a importância prévia da preparação da família para a adoção de irmãos e a necessidade de um cuidado maior com o filho que desempenhou o papel parental com o grupo de irmãos antes da adoção.The experience of motherhood by adopting a group of biological siblings can be a challenge during the post-adoption, but the literature on the subject is scarce. The objective of the present study was to understand how to build a mother-child relationship in a case of adoption of a group of siblings during ten psychotherapy sessions with a psychoanalytic and attachment-based theoretical framework. Thematic Analysis was used in psychotherapy transcriptions to look for the effects of mother-three child adaptations and to identify patterns of themes and subthemes. The results highlighted a period of idealization of the youngest children, sustained by difficulties with the older child. These difficulties were overcome when the mother saw younger children as more accurate and identified herself with the older one. It took a period of intense maternal emotional availability for the individualized needs of her three children as if they were triplets of different ages. The results emphasized the importance of pre-adoption preparation for the family to adopt siblings. Also, it is essential to pay special attention to the child who played a parental role before the adoption

The influence of viscosity on the motility and sensory ability of the dinoflagellate Heterocapsa triquetra

Seawater viscosity is influenced by temperature as well as through excretion of exopolymers by some plankton. We examined the role of viscosity on the movement patterns and sensory abilities of the dinoflagellate Heterocapsa triquetra, manipulating the viscosity of seawater to simulate a 10+1.58C temperature change. In a second treatment, we seeded the water with microbeads to examine swimming behaviours in the presence of a mechanical stimulus. Increased viscosity reduced distances between conspecifics 4.7-fold and increased distances between protists and microbeads by 3.4-fold. Increased viscosity also affected other aspects of motility, with an overall reduction in swimming speed of 2.0- and 7.0-fold for treatments with and without mechanical stimuli. Higher viscosities were associated with upward vertical migration, in both the presence and absence of microbeads. Cells were highly sensitive to disturbances to the velocity field, by as little as 1.5%, and different approach distances of H. triquetra to conspecifics over mechanical stimuli suggest sensory capacity to distinguish types of particles. Mediation of motility and migratory behaviours through viscosity implies ramifications for the distribution of protists and their encounters with resources, predators and conspecifics triggered by events such as temperature changes and phytoplankton bloom events