A second-order conditional moment closure model for the simulation of a lifted turbulent flame

This paper presents the results of a second-order closure Conditional Moment Closure model applied to a lifted turbulent H 2 -air flame. The objective is to find out how a second-order closure will modify the lift-off height compared to first-order results. A 10-step chemical mechanism is used to predict rates of reaction in hydrogen-air mixtures but the second-order correction terms are calculated using one-step chemistry. First a progress variable for this reduced mechanism is defined and an additional equation for its conditional variance is derived. The level of the conditional fluctuation is found to be around 30% of its maximum value for stoichiometric mixtures in the flame stabilisation area. The second-order closure has a distinct effect on the flame position determined in the simulations

EXPLORATORY INVESTIGATION OF MULTIPLE MAPPING CLOSURE AS A MIXING MODEL IN LES-CMC

Abstract The scalar dissipation rate is a key quantity in turbulent combustion modelling, in particular for Conditional Moment Closure (CMC). Within the CMC framework, its conditional average at a particular value of mixture fraction is of special interest. The present study examines the deterministic version of Multiple Mapping Closure (MMC) to evaluate the conditionally filtered scalar dissipation rate in the filtered CMC equations in the context of Large Eddy Simulation (LES). The objectives of the present investigation are (i) to use MMC to model the conditionally filtered scalar dissipation rate needed in LES-CMC and (ii) to determine if MMC is a viable option in the proposed framework. The paper presents our first results and focuses on the MMC equation, the role of each term in the MMC governing equation and the submodels needed. One major scalar is selected, mixture fraction. The MMC transport equation is implemented in a LES code coupled with CMC to simulate a lifted jet flame in a vitiated coflow. At this initial stage of the present MMC study, it is useful to separate the MMC results and investigate the MMC operation and modelling alone before solving LES, CMC and MMC together. Thus, the MMC equation is solved starting from frozen flow, mixing and temperature fields. Discussion is focused on the models of the MMC unclosed terms and their impact on the prediction of the mapping function and the conditionally filtered scalar dissipation rate. The issue related to low levels of predicted subgrid variance in MMC compared to what is predicted in the LES solver is investigated. Introduction The scalar dissipation rate is a key quantity in turbulent combustion modelling, in particular for flamelet, Conditional Moment Closure (CMC) and Probability Density Function (PDF) approaches [1]. The scalar dissipation rate, N, represents the rate of mixing at the molecular level and is proportional to the mean square gradient of the scalar, Z, such as N ≡ D ∇Z ·∇Z, where D is the molecular diffusivity of Z. Within the CMC framework, its conditional average at a particular value, η, of mixture fraction, Z is of special interest with N|η = D∇Z · ∇Z|Z = η . The angular brackets denote a conditional average over an ensemble of realizations of the flow, subject to the condition to the right of the vertical bar. Accurate modelling of the conditional scalar dissipation rate is crucial, as it appears in both the conditional species transport and temperature equations. However, evaluation of N|η is not straightforward. Further, CMC requires solution of the transport equations for the conditional averages to be consistent with that of the PDF transport equatio

Neuroactive Steroid 3α-Hydroxy-5α-Pregnan-20-One Modulates Electrophysiological and Behavioral Actions of Ethanol

Neuroactive steroids are synthesize

The repeatability of cognitive performance:A meta-analysis

This is the author accepted manuscript. The final version is available from The Royal Society via the DOI in this record.Behavioural and cognitive processes play important roles in mediating an individual's interactions with its environment. Yet, while there is a vast literature on repeatable individual differences in behaviour, relatively little is known about the repeatability of cognitive performance. To further our understanding of the evolution of cognition, we gathered 44 studies on individual performance of 25 species across six animal classes and used meta-analysis to assess whether cognitive performance is repeatable. We compared repeatability (R) in performance (1) on the same task presented at different times (temporal repeatability), and (2) on different tasks that measured the same putative cognitive ability (contextual repeatability). We also addressed whether R estimates were influenced by seven extrinsic factors (moderators): type of cognitive performance measurement, type of cognitive task, delay between tests, origin of the subjects, experimental context, taxonomic class and publication status. We found support for both temporal and contextual repeatability of cognitive performance, with mean R estimates ranging between 0.15 and 0.28. Repeatability estimates were mostly influenced by the type of cognitive performance measures and publication status. Our findings highlight the widespread occurrence of consistent inter-individual variation in cognition across a range of taxa which, like behaviour, may be associated with fitness outcomes.PKYC is supported by Japan Society for the Promotion of Science (PE1801); JOvH was funded by an ERC consolidator grant (616474). MC and this research was supported by a grant from the Human Frontier Science Program to ASC and JM-F (RGP0006/2015)

A Wasp Manipulates Neuronal Activity in the Sub-Esophageal Ganglion to Decrease the Drive for Walking in Its Cockroach Prey

BACKGROUND: The parasitoid Jewel Wasp hunts cockroaches to serve as a live food supply for its offspring. The wasp stings the cockroach in the head and delivers a cocktail of neurotoxins directly inside the prey's cerebral ganglia. Although not paralyzed, the stung cockroach becomes a living yet docile 'zombie', incapable of self-initiating spontaneous or evoked walking. We show here that such neuro-chemical manipulation can be attributed to decreased neuronal activity in a small region of the cockroach cerebral nervous system, the sub-esophageal ganglion (SEG). A decrease in descending permissive inputs from this ganglion to thoracic central pattern generators decreases the propensity for walking-related behaviors. METHODOLOGY AND PRINCIPAL FINDINGS: We have used behavioral, neuro-pharmacological and electrophysiological methods to show that: (1) Surgically removing the cockroach SEG prior to wasp stinging prolongs the duration of the sting 5-fold, suggesting that the wasp actively targets the SEG during the stinging sequence; (2) injecting a sodium channel blocker, procaine, into the SEG of non-stung cockroaches reversibly decreases spontaneous and evoked walking, suggesting that the SEG plays an important role in the up-regulation of locomotion; (3) artificial focal injection of crude milked venom into the SEG of non-stung cockroaches decreases spontaneous and evoked walking, as seen with naturally-stung cockroaches; and (4) spontaneous and evoked neuronal spiking activity in the SEG, recorded with an extracellular bipolar microelectrode, is markedly decreased in stung cockroaches versus non-stung controls. CONCLUSIONS AND SIGNIFICANCE: We have identified the neuronal substrate responsible for the venom-induced manipulation of the cockroach's drive for walking. Our data strongly support previous findings suggesting a critical and permissive role for the SEG in the regulation of locomotion in insects. By injecting a venom cocktail directly into the SEG, the parasitoid Jewel Wasp selectively manipulates the cockroach's motivation to initiate walking without interfering with other non-related behaviors

Simple Ways to Measure Behavioral Responses of Drosophila to Stimuli and Use of These Methods to Characterize a Novel Mutant

The behavioral responses of adult Drosophila fruit flies to a variety of sensory stimuli – light, volatile and non-volatile chemicals, temperature, humidity, gravity, and sound - have been measured by others previously. Some of those assays are rather complex; a review of them is presented in the Discussion. Our objective here has been to find out how to measure the behavior of adult Drosophila fruit flies by methods that are inexpensive and easy to carry out. These new assays have now been used here to characterize a novel mutant that fails to be attracted or repelled by a variety of sensory stimuli even though it is motile

A collaborative VR Murder Mystery using Photorealistic User Representations

The VRTogether project has developed a Social VR platform for remote communication and collaboration. The hyper-realistic representation of users, as volumetric video, allows for natural interaction in a virtual environment with others. This video shows one of the use cases, an escape room style, where remote users need to collaboratively resolve a murder mystery. The experience takes place in the victim’s apartment where the police team (avatars) together with up to four real-time captured users (point clouds), work as a team to find clues and come up with a conclusion about what happened to the victim and who was the criminal. This experience includes a layer of interaction, enabling the users to interact with the environment, by touching objects, and to talk to the characters. It also allows for navigating between the rooms of the apartment. The experience provides immersion and social connectedness, where users are protagonists of the story, sharing the virtual environment and following the narrative. The combination of virtual reality environments (space and characters) with novel technologies for real-time volumetric video conferencing enables unique new experiences in a number of areas such as healthcare, broadcasting, and gaming. The video can be watched here: https://youtu.be/Hsj1YWo55k

Abstract concept learning in a simple neural network inspired by the insect brain

The capacity to learn abstract concepts such as 'sameness' and 'difference' is considered a higher-order cognitive function, typically thought to be dependent on top-down neocortical processing. It is therefore surprising that honey bees apparantly have this capacity. Here we report a model of the structures of the honey bee brain that can learn sameness and difference, as well as a range of complex and simple associative learning tasks. Our model is constrained by the known connections and properties of the mushroom body, including the protocerebral tract, and provides a good fit to the learning rates and performances of real bees in all tasks, including learning sameness and difference. The model proposes a novel mechanism for learning the abstract concepts of 'sameness' and 'difference' that is compatible with the insect brain, and is not dependent on top-down or executive control processing