Cooperation of Sperm in Two Dimensions: Synchronization, Attraction and Aggregation through Hydrodynamic Interactions

Sperm swimming at low Reynolds number have strong hydrodynamic interactions when their concentration is high in vivo or near substrates in vitro. The beating tails not only propel the sperm through a fluid, but also create flow fields through which sperm interact with each other. We study the hydrodynamic interaction and cooperation of sperm embedded in a two-dimensional fluid by using a particle-based mesoscopic simulation method, multi-particle collision dynamics (MPC). We analyze the sperm behavior by investigating the relationship between the beating-phase difference and the relative sperm position, as well as the energy consumption. Two effects of hydrodynamic interaction are found, synchronization and attraction. With these hydrodynamic effects, a multi-sperm system shows swarm behavior with a power-law dependence of the average cluster size on the width of the distribution of beating frequencies

Non-linear effects on Turing patterns: time oscillations and chaos.

We show that a model reaction-diffusion system with two species in a monostable regime and over a large region of parameter space, produces Turing patterns coexisting with a limit cycle which cannot be discerned from the linear analysis. As a consequence, Turing patterns oscillate in time, a phenomenon which is expected to occur only in a three morphogen system. When varying a single parameter, a series of bifurcations lead to period doubling, quasi-periodic and chaotic oscillations without modifying the underlying Turing pattern. A Ruelle-Takens-Newhouse route to chaos is identified. We also examined the Turing conditions for obtaining a diffusion driven instability and discovered that the patterns obtained are not necessarily stationary for certain values of the diffusion coefficients. All this results demonstrates the limitations of the linear analysis for reaction-diffusion systems

Variation of turbulent burning rate of methane, methanol, and iso-octane air mixtures with equivalence ratio at elevated pressure

Turbulent burning velocities for premixed methane, methanol, and iso-octane/air mixtures have been experimentally determined for an rms turbulent velocity of 2 m/s and pressure of 0.5 MPa for a wide range of equivalence ratios. Turbulent burning velocity data were derived using high-speed schlieren photography and transient pressure recording; measurements were processed to yield a turbulent mass rate burning velocity, utr. The consistency between the values derived using the two techniques, for all fuels for both fuel-lean and fuel-rich mixtures, was good. Laminar burning measurements were made at the same pressure, temperature, and equivalence ratios as the turbulent cases and laminar burning velocities and Markstein numbers were determined. The equivalence ratio (φ) for peak turbulent burning velocity proved not always coincident with that for laminar burning velocity for the same fuel; for isooctane, the turbulent burning velocity unexpectedly remained high over the range φ = 1 to 2. The ratio of turbulent to laminar burning velocity proved remarkably high for very rich iso-octane/air and lean methane/air mixtures

Noise-induced temporal dynamics in Turing systems

We examine the ability of intrinsic noise to produce complex temporal dynamics in Turing pattern formation systems, with particular emphasis on the Schnakenberg kinetics. Using power spectral methods, we characterize the behavior of the system using stochastic simulations at a wide range of points in parameter space and compare with analytical approximations. Specifically, we investigate whether polarity switching of stochastic patterns occurs at a defined frequency. We find that it can do so in individual realizations of a stochastic simulation, but that the frequency is not defined consistently across realizations in our samples of parameter space. Further, we examine the effect of noise on deterministically predicted traveling waves and find them increased in amplitude and decreased in speed

Using video and multimodal classroom interaction analysis to investigate how information, misinformation, and disinformation influence pedagogy

Misinformation is accidentally wrong and disinformation is deliberately incorrect (i.e., deception). This paper uses the Pedagogy Analysis Framework (PAF) to investigate how information, misinformation, and disinformation influence classroom pedagogy. 95 people participated (i.e., one lesson with 7-year-olds, another with 10-year-olds, and three with a class of 13-year-olds). We used four video-based methods (lesson video analysis, teacher verbal protocols, pupil group verbal protocols, and teacher interviews). 35 hours of video data (recorded 2013-2020) were analysed using Grounded Theory Methods by the researchers, the class teachers, and groups of pupils (three girls and three boys). The methodology was Straussian Grounded Theory. We present how often participants used information, misinformation, and disinformation. We illustrate how the PAF helps understand and explain information, misinformation, and disinformation in the classroom by analysing video data transcripts. In addition, we discuss participant perceptions of the status of information; overlapping information, misinformation, and disinformation; and information communication difficulties

Teachers' perspectives on the relationship between secondary school departments of science and religious education: Independence or mutual enrichment?

There is a gap in the research on the relationship between secondary school subject departments, particularly where, as in the case of science and religious education (RE), there is not the traditional relationship that may be seen in science and maths or across humanities subjects. More awareness of content taught in other departments is important for pupils' coherent experience of curriculum and schooling. This article reports on data from 10 focus groups with 50 participants from six universities, where student teachers of science and RE revealed a complex picture of relationships between the two departments in their placement schools. Furthermore, this article reports findings from a survey where 244 teachers and student teachers of science and RE shared their perspectives on the relationship between the two school departments. The measure was adapted from Barbour's typology, a classification describing the nature of the relationship between science and religion in a range of literature. The terms ‘conflict’, ‘independence’, ‘dialogue’, ‘collaboration’ and ‘integration’ were presented to teachers of both subjects. Little evidence was found of conflict between science and RE departments, but more ‘independence’ than ‘dialogue’ between the two departments was reported. In the light of these findings, the benefits of boundary crossing are explored alongside the role teachers should play in boundary crossing

Multimodal classroom interaction analysis using video-based methods of the pedagogical tactic of (un)grouping

Grouping of people and/or things in school can involve challenging pedagogical problems and is a recurrent issue in research literature. Grouping of pupils sometimes aids learning, but detailed video-based analysis of how teachers (and pupils) group or ungroup (termed ‘(un)grouping’) in classrooms is rare. This multimodal classroom interaction analysis study builds on previous work by exploring how the Pedagogy Analysis Framework can help untangle complicated classroom interactions involving (un)grouping and identifies sixteen types of (un)grouping. The sample size is one class of thirty pupils (10-year-olds), their class teacher, and teaching assistant. Four research methods were used (lesson video analysis, teacher verbal protocols, pupil group verbal protocols, and individual teacher interviews). Six hours of data were video recorded (managed using NVivo). Data were analysed by two educational researchers, the class teacher, and two groups of pupils (three girls and three boys). The methodology is Straussian Grounded Theory. Data were recorded in 2019. We present how often participants (un)grouped during a lesson. We propose and use a grounded theory for (un)grouping which we call the ‘Exclusion, Segregation, Integration, and Inclusion (ESII) model’. Additionally, we discuss how misinformation and disinformation can complicate analysis of (un)grouping and examine different perspectives on (un)grouping

Declaration of medical writing assistance in international peer-reviewed publications

Medical researchers have an ethical and scientific obligation to publish, but between one third and two thirds of research may remain unpublished. A major reason for nonpublication is lack of time, which may lead researchers to seek medical writing assistance. Guidelines from journal editors and medical writers encourage authors to acknowledge medical writers. We quantified the proportion of articles from international, peer-reviewed, high-ranking journals that reported medical writing assistance