Evaluation of a Limited-area Energy Budget Cycle of an Extratropical Storm Under Lagrangian and Eulerian Frameworks

To conceptualize the uncertainties regarding the mechanisms of extratropical cyclones (EC), a study of their energy cycle can provide key information of their fundamental structure. This study applies a set of equations built from earlier works for a limited-area energy decomposed into temporal mean and deviations. It compares the results obtained with a reference frame that tracks an EC through its eddy kinetic energy with those obtained with a larger but fixed frame. A specific storm that occurred throughout the period of December 10-18th 2004 and simulated by the Canadian Regional Climate Model (CRCM – version 5) was studied. Results support the notion that the moving reference results in larger amplitudes for all temporal deviation components of the cycle than for the fixed reference. A time tendency analysis of the energetic reservoirs reveals noteworthy phases in the storm’s energy, with an increase and decrease occurring during the periods of 10-14 December and 14-18 December, respectively. The energy budget is overall fairly well balanced, with the exception of a lateral boundary term, hkTV , with considerable negative values; this term exhibits a spatially larger scale than the other contributions in the EC. An evaluation of the sensibility of the tracking scheme related to its size and positioning was also performed to determine its influence on the boundary term hkTV.

Discrimination of regular and irregular rhythms by accumulation of time differences

Perceiving the temporal regularity in a sequence of repetitive sensory events facilitates the preparation and execution of relevant behaviors with tight temporal constraints. How we estimate temporal regularity from repeating patterns of sensory stimuli is not completely understood. We developed a decision-making task in which participants had to decide whether a train of visual, auditory, or tactile pulses, had a regular or an irregular temporal pattern. We tested the hypothesis that subjects categorize stimuli as irregular by accumulating the time differences between the predicted and observed times of sensory pulses defining a temporal rhythm. Results show that instead of waiting for a single large temporal deviation, participants accumulate timing-error signals and judge a pattern as irregular when the amount of evidence reaches a decision threshold. Model fits of bounded integration showed that this accumulation occurs with negligible leak of evidence. Consistent with previous findings, we show that participants perform better when evaluating the regularity of auditory pulses, as compared with visual or tactile stimuli. Our results suggest that temporal regularity is estimated by comparing expected and measured pulse onset times, and that each prediction error is accumulated towards a threshold to generate a behavioral choice.

Intestinal immune maturation is accompanied by temporal changes in the composition of the microbiota

In animals establishment of the intestinal microbial ecosystem is influenced by mucosal immune functions. As mucosal immune functions dynamically change during development of juvenile layer chicken, this study focused on dynamics in the ileal microbiota composition in relation to intestinal immune development. In addition, the levels of immunoglobulin (Ig) in serum and amount of bacteria coated with IgA, a hallmark of intestinal immune maturation, were analysed. The composition of the intestinal microbiota transiently changed at the age of 14-42 days compared to the microbiota composition before and after this period. This temporal deviation in microbiota composition was associated to a temporal increase in transcriptional activity of pro-inflammatory cytokine genes. Furthermore, before week two limited amounts of faecal bacteria were bound by IgM and from week two increasing amounts of bacteria were bound by IgA, reaching a maximal level of 70% of IgA-coated bacteria at 6 weeks of age. These data could indicate that prior to achievement of intestinal homeostasis at 6-10 weeks post hatch, activation of inflammatory pathways cause a temporal disturbance of the microbiota composition. This period of imbalance may be essential for adequate immune development and establishment of intestinal homeostasis.

Quantifying Microtiming Patterning and Variability in Drum Kit Recordings

Human performers introduce temporal variability in their performance of music. The variability consists of both long-range tempo changes and microtiming variability that are note-to-note level deviations from the nominal beat time. In many contexts, microtiming is important for achieving certain preferred characteristics in a performance, such as hang, drive, or groove; but this variability is also, to some extent, stochastic. In this paper, we present a method for quantifying the microtiming variability. First, we transcribed drum performance audio files into empirical data using a very precise onset detection system. Second, we separated the microtiming variability into two components: systematic variability (SV), defined as recurrent temporal patterns, and residual variability (RV), defined as the residual, unexplained temporal deviation. The method was evaluated using computer-performed audio drum tracks and the results show a slight overestimation of the variability magnitude, but proportionally correct ratios between SV and RV. Thereafter two data sets were analyzed: drum performances from a MIDI drum kit and real-life drum performances from professional drum recordings. The results from these data sets show that up to 65 percent of the total micro-timing variability can be explained by recurring and consistent patterns.

Auditorily Paced Keytapping Performance during Synchronous, Decreased, and Delayed Visual Feedback

20 young adult female Ss tapped on a tapping key to low, mid, and high sensation-level pure-tone auditory-pacing stimuli while being exposed to synchronous visual-feedback, delayed visual-feedback, and decreased sensory-feedback conditions. The stroboscopic visual-feedback stimulus was judged to be as bright as the mid-sensation-level auditory stimulus was loud in a preliminary cross-modality matching study. The dependent variables evaluated were tapping error, temporal deviation of the taps from the onset of the pacing stimuli, and tap duration. Few tapping errors occurred under any of the conditions which indicated that the auditory sensory modality is effective in regulating motor performance even when temporally distorted visual feedback is associated with the performance. Tapping deviation data strongly suggested that the relative perceptual magnitudes between the auditory pacing stimuli and the delayed visual-feedback stimulus are important factors in determining the speed of motor response. Tap durations were greater during decreased sensory-feedback and delayed visual-feedback conditions than during synchronous visual-feedback conditions, and it was speculated that these changes occurred due to an increase in tactual and kinesthetic feedback employed by Ss to counterbalance the distorted and decreased sensory feedbacks.