Bar Release Research Articles

Improvising on the Fly: Comparison of a Novel Technique for Emergent Zipper Release to a Well-Established Technique in a Simulated Setting

BackgroundPenile skin zipper entrapment is an emergent medical condition in which the penile skin, scrotal skin, or foreskin gets caught within the teeth of a zipper or the slider itself. This can lead to complications such as urethral involvement, skin loss, or tissue necrosis. We propose a novel technique to aid in the release of entrapped skin utilizing wire cutters directed at the inferior portion of the zipper pull. ObjectivesTo describe a novel technique to free entrapped penile skin and compare its performance to the well-established median bar technique in a simulated setting. MethodsA randomized cross-over design was used to compare techniques on successful release, time to release and tissue injury using an animal model of raw chicken skin entrapped in a zipper. Statistical significance was assessed at p < 0.05. ResultsTwenty-two participants were included. There was no statistically significant difference between the novel technique and the median bar technique regarding successful release (100% vs 95.5%, respectively), median time to release (29.1 vs 26.4 seconds, respectively), or frequency of tissue injury (22.7% vs 27.3%). ConclusionPerformance using our novel technique for removal of penile skin from a zipper is similar to the median bar release technique regarding. Our novel technique may be a valid treatment option for the release of entrapped penile skin in a zipper mechanism in the emergency department setting.

Sensitivity Analysis of Holdback Bar Release Load during Catapult-Assisted Takeoff of Carrier-Based Aircraft

The release load of holdback bar will affect the safety of catapult-assisted takeoff of carrier-based aircraft, and the accurate control of releasing the load will ensure success. The magnitude and the control accuracy of release load are important parameters which impact the takeoff performance, therefore unstable release load and insufficient release precision are the main factors affecting the takeoff safety. In this paper, mechanical models of the carrier-based aircraft in the catapult-assisted takeoff tensioning state and gliding state after release are established based on multi-body dynamics, contact mechanics and tribological theory, and the influence of the release load of the holdback bar on the catapult-assisted takeoff performance is analyzed. Furthermore, a kinetic model of the holdback bar device is established, and the kinetic characteristics of the release process of the holdback bar are studied. Based on the kinetic model and friction model of the holdback bar, the influencing factors of the sensitivity of the holdback bar release load are analyzed and the structural parameters are optimized. The results show that the released load decreases slowly with the increase of the contact surface angle of the holdback bar structure and increases rapidly when that angle reaches the critical value; besides, the release load increases slowly with the increase of the friction coefficient of the contact surface and increases faster when the critical friction coefficient is reached.

Development of a Small-Scale Electromechanical Mobile Fish Feeder

The aim of the present study was to develop and test a simple small-scale electromechanical mobile fish feeder to control feeding in indoor or outdoor fish ponds. Fish feeder spreader consists of a solid frame, fish feed hopper, distributing disc with spreading fins, transmission system and electrical components. The electrical components include the rotational speed motor, distribution switch box, battery, dosage bar release motor, and transmission system dc brushed motors. Analysis and evaluation of distribution pattern of fish feed done under two different spreading disk rotational speeds of 1000 and 1250 rpm (17.3 and 21.6 ms-1), two feed outlet control slide settings for fish feed rate and three different fish feed types. The developed prototype can achieve 4.9 and 5.8 kg/min distribution rate of fish feed type 1 (sizes from 1 to 2 mm and average bulk density of 530 kg m-3) under two distribution disc rotational speed of 1000 rpm and 1250 rpm respectively. Variation on distribution of feed material type 1 in both sides of the developed prototype was 8.4 and 14.7 % for disk rotational speed 1000 rpm and 1250 rpm respectively with at most good distribution pattern. Feed distribution uniformity for feed type 2 (sizes from 2 to 3 mm and average bulk density of 720 kg m-3) was much better compare to the distribution pattern of feed type. Where, there was variation on distribution of feed material type 2 in both sides of the developed prototype by 3.5 and 3.11 % for disk rotational speed 1000 rpm and 1250 rpm respectively under outlet slide settings 2. Even with outlet slide settings 2 (only half of the outlet opening), distribution of feed material type 2 in both sides of the developed prototype was better and recorded 2.21 and 2.61 % for disk rotational speed 1000 rpm and 1250 rpm respectively. Using fish feed material with size bigger than 3 mm will lead to uneven distribution using current developed prototype.

Performance on a visual search task using random dot motion stimuli

The priority map hypothesis posits that visual attention is allocated according to the priority of objects in the visual scene. We and others have suggested that activity in priority maps during visual search might explain behavior based on the accumulation of evidence at each stimulus location (Purcell et al, 2012; Arcizet et al, 2018; Servant et al, 2019), however these studies have utilized simple stimuli that require little temporal integration of information. In this study, we use random dot stimuli in visual search to quantify how the accumulation of evidence changes under distinctive conditions within visual search. Two adult animals were trained on a visual search task in which 1, 2 or 4 random moving dot stimuli were presented. One subject indicated the presence of a target (a stimulus with rightwards motion) by making a saccade to the target. The other subject indicated the presence of a target by releasing one of two bars. The number of stimuli and the coherence of the stimuli were changed on each trial, such that all stimuli had the same coherence. Targets were present on 50% of trials for set size 1, 66% of trials for set size 2, 80% of trials for set size 4 in the saccade task and 66% of trials for set size 4 in the bar release task. In a subset of trials with a set size of 4, we also had a spatial cue condition and a feature-based cue condition. We found a decrease in performance, hit rate, and correct rejections for the greater set sizes. In the spatial cue and feature-based cue conditions, we found an increase in hit rates and decrease in reaction times. These behavioral data show that our task should allow us to measure the neural accumulation of evidence in a visual search task.

Numerical predictions of cryogenic hydrogen vertical jets

Comparison of Computational Fluid Dynamics (CFD) predictions with measurements is presented for cryo-compressed hydrogen vertical jets. The stagnation conditions of the experiments are characteristic of unintended leaks from pipe systems that connect cryogenic hydrogen storage tanks and could be encountered at a fuel cell refueling station. Jets with pressure up to 5 bar and temperatures just above the saturation liquid temperature were examined. Comparisons are made to the centerline mass fraction and temperature decay rates, the radial profiles of mass fraction and the contours of volume fraction. Two notional nozzle approaches are tested to model the under-expanded jet that was formed in the tests with pressures above 2 bar. In both approaches the mass and momentum balance from the throat to the notional nozzle are solved, while the temperature at the notional nozzle was assumed equal to the nozzle temperature in the first approach and was calculated by an energy balance in the second approach. The two approaches gave identical results. Satisfactory agreement with the measurements was found in terms of centerline mass fraction and temperature. However, for test with 3 and 4 bar release the concentration was overpredicted. Furthermore, a wider radial spread was observed in the predictions possibly revealing higher degree of diffusion using the k-ε turbulence model. An integral model for cryogenic jets was also developed and provided good results. Finally, a test simulation was performed with an ambient temperature jet and compared to the cold jet showing that warm jets decay faster than cold jets.

Rapid Release Polymeric Fibers for Inhibition of Porphyromonas gingivalis Adherence to Streptococcus gordonii.

Active agents targeting key bacterial interactions that initiate biofilm formation in the oral cavity, may alter periodontitis progression; however, to date, specifically-targeted prophylactic and treatment strategies have been limited. Previously we developed a peptide, BAR (SspB Adherence Region), that inhibits oral P. gingivalis/S. gordonii biofilm formation in vitro and in vivo, and BAR nanoparticles that increase BAR effectiveness via multivalency and prolonged delivery. However, limited BAR loading and nanoparticle retention in the oral cavity can result in inadequate release and efficaciousness. Given this, an effective delivery platform that can release concentrations of BAR suitable for twice-daily applications, may offer an alternative that enhances loading, ease of administration, and retention in the oral cavity. With this in mind, the study objectives were to develop and characterize a rapid-release platform, composed of polymeric electrospun fibers (EFs) that encapsulate BAR, and to evaluate fiber safety and functionality against P. gingivalis/S. gordonii biofilms in vitro. Poly(lactic-co-glycolic acid) (PLGA), poly(L-lactic acid) (PLLA), and polycaprolactone (PCL) were electrospun alone or blended with polyethylene oxide (PEO), to provide high BAR loading and rapid-release. The most promising formulation, 10:90 PLGA:PEO EFs, provided 95% BAR release after 4 h, dose-dependent inhibition of biofilm formation (IC50 = 1.3 μM), disruption of established dual-species biofilms (IC50 = 2 μM), and maintained high cell viability. These results suggest that BAR-incorporated EFs may provide a safe and specifically-targeted rapid-release platform to inhibit and disrupt dual-species biofilms, that we envision may be applied twice-daily to exert prophylactic effect in the oral cavity.

Influence of thermobaric conditions on size distribution of colloidal gas aphrons

Abstract A new technique for the preparation of monodisperse colloidal gas aphrons (CGA) stable at reservoir conditions is developed. The behavior of such aphrons under compression–decompression protocols with pressure in the range 1–500 bar and pressure release rate in the range 50–3000 bar/min is studied with optical microscopy and densimetry. An image processing algorithm is developed for counting the aphrons and measuring the aphron size distribution. It is shown that the dispersity of the aphron system is independent of pressure. The dependence of the mean aphron size versus time follows Lifschitz–Slyozov law which is characteristic of wet foam coarsening. The monodisperse CGAs produced can be successfully used as pressure–temperature controlled systems for various oilfield applications

Investigating optimal technique in the presence of motor system noise: application to the double layout somersault dismount on high bar

Minimising joint torque is often used as an optimisation criterion when investigating human movement. Alternatively, an aspect of performance may be chosen to be maximised when investigating sporting movements. The aim of the study was to optimise the technique in the backward giant circle prior to a double layout somersault dismount from the high bar using various criteria to determine which best characterised the technique adopted by a gymnast. Ten recorded gymnast trials were used to determine bar release parameters and the level of noise in the gymnast’s movements. A computer simulation model of a gymnast and bar was used to optimise giant circle technique under three criteria: minimising joint torques, maximising the release window and maximising success in the presence of motor system noise. Local and global optimisations of technique were performed using the three criteria starting from the average technique of the 10 recorded trials. All global optimum solutions diverged from the gymnast’s technique. The local optimum for maximising success in the presence of noise had a success rate comparable with the global optimum (98% vs. 100%, respectively). It is concluded that the gymnast’s technique is characterised by maximising success despite operating with motor system noise.

Biomechanical Characteristics of Key Elements of Gienger Salto Technique on Uneven Bars

The purpose of the paper is to highlight the biomechanical characteristics of Gienger salto on uneven bars at junior girl gymnasts aged 12 to 14. The results of the spatial – temporal characteristics of sports technique key elements of stretched Gienger salto on uneven bars highlights the phasic sequence of execution, namely the preparatory movement of launching from forward giant, moment of bar release, multiplication of body posture and the concluding posture of regrasping the bar in accordance with the technical requirements of FIG Code of Points. The effective use of the video biomechanical analysis method of stretched Gienger salto on uneven bars highlighted the kinematic and dynamic characteristics of sports technique key elements in accordance with the performances achieved in competitions.

Is working more costly than waiting in monkeys?

We studied how value for instrumental action is discounted by predicted effort and delay. The monkeys were trained to perform instrumental trials that required a bar release when a visual target changed from red-to-green. There were two trial conditions. In delay trials, after the monkeys performed one instrumental trial correctly a reward was delivered 0–7 seconds later. In work trials, the monkeys had to perform 0, 1, or 2 additional instrumental trials to obtain a reward. The lengths of trials in delay matched the time it took to complete work trials. The length of delay or number of trials was indicated by a visual cue presented throughout the trial. Our hypothesis was that the monkeys would all show temporal discounting of reward in the delay trials, and that in the work trials the monkeys’ performance might reflect an additional cost due to working. The error rate increased linearly as remaining cost increased for all 8 monkeys. For 4 monkeys the error rate was significantly larger in work trials than in delay trials (effort sensitive monkeys). For the other 4 monkeys there was no significant difference in error rate (effort insensitive monkeys). Since the error rate has an inverse relation with value for action, these results suggest that value is discounted hyperbolically by effort as well as by delay. Error rates generally increased as the testing sessions progressed and the total reward accumulated (i.e., effect of reward devaluation). The relative impact of delay and effort on error rates was reasonably stable within subjects. Thus, within the monkey population there seems to be a significant dichotomy in the sensitivity governing whether working is more costly than waiting, possibly arising from a constitutional or genetic trait.

Shoulder muscles recruitment during a power backward giant swing on high bar: A wavelet-EMG-analysis

This study aimed at determining the upper limb muscles coordination during a power backward giant swing (PBGS) and the recruitment pattern of motor units (MU) of co-activated muscles. The wavelet transformation (WT) was applied to the surface electromyographic (EMG) signal of eight shoulder muscles. Total gymnast’s body energy and wavelet synergies extracted from the WT-EMG by using a non-negative matrix factorization were analyzed as a function of the body position angle of the gymnast. A cross-correlation analysis of the EMG patterns allowed determining two main groups of co-activated muscles. Two wavelet synergies representing the main spectral features (82% of the variance accounted for) discriminated the recruitment of MU. Although no task-group of MU was found among the muscles, it appeared that a higher proportion of fast MU was recruited within the muscles of the first group during the upper part of the PBGS. The last increase of total body energy before bar release was induced by the recruitment of the muscles of the second group but did not necessitate the recruitment of a higher proportion of fast MU. Such muscle coordination agreed with previous simulations of elements on high bar as well as the findings related to the recruitment of MU.

Neuronal activity reflecting progression of trials in the pre-supplementary motor area of macaque monkey: An expression of neuronal flexibility

We studied the activity of single neurons in the pre-supplementary motor area (pre-SMA) of macaque monkeys as they performed two visuomotor tasks, called the visual fixation task and the visual fixation-blink task. Both tasks involved a sequence of three visual stimuli, red followed by yellow and green. The tasks differed in that the latter one had a gap within the period of the red stimulus, called a “blink”. The tasks were performed in two modes, one of which included movements of both the arm and eye and the other of which involved only eye movements. In the arm–eye mode, the monkeys had to press a bar and fixate the red stimulus that appeared after bar press. To receive a reward, both the bar press and visual fixation had to be maintained until the green stimulus triggered bar release. In the eye mode, bar press and bar release were eliminated from the task. Of the 42 neurons active during the visual fixation task, 15 showed task-related activity in both arm–eye and eye modes, and our analysis focused on these cells. We found that the introduction of the blink in visual fixation-blink task abolished the task-related activity of these cells over the course of 2–4 trials. This finding suggests a role for the pre-SMA in reflecting progression of trials as an updating of motor instruction.

The dynamics of cost and benefit representations by noradrenaline and dopamine neuronal activity, and their relation to goal-directed behavior

Higher brain functions that rely on attention and reward seeking depend on the integrity of neuromodulatory systems using dopamine (DA) and noradrenaline (NA). Despite the importance for these neuromodulators, there have been no direct experimental comparisons of the selectivity of DA and NA neurons, so making statements about the differences in functionality are speculative. We have recorded activity from dopamine neurons of the substantia nigra pars compacta and noradraline neurons of the locus coeruleus in monkeys while the monkeys carried out a visually-cued reward schedule task.In this task, the monkeys perform schedules of 1, 2, or 3 red-to-green sequential color discrimination trials to earn a reward. A cue presented at the beginning of each trial shows how many trials must yet be completed to obtain a reward. Error rates increase in this simple task as the number of trials yet to be performed before a reward increase, even though the red-green discrimination is identical in every trial, indicating that the reward value is discounted as a function of trials remaining before reward (at type of temporal discounting). We also find lip movements that occur when cue appears and at bar release (bar release is the correct response to a red->green color change). The lipping at the cue occurs whenever a new schedule begins, and is not related to the number of trials to be carried out. At bar release, lipping is strongest in rewarded trials. We interpret the lipping as reflecting the value of the event at that instant. Both DA and NA neurons seem to reflect the lipping response, with responses occurring when the cue appears in first trials, and at the time of bar-release. The neuronal responses that occur when the cue appears are similar, with both DA and NA neurons showing activations in the first trial of a schedule. At bar release, however, the activity furthest from reward is largest for NA neurons, whereas for DA neurons the greatest activity occurs in the rewarded trials. Our data lead us to suggest that both systems are simultaneously evaluating the subjective or perceived value of the current state, but in different ways. We suggest that the noraderaline system reflects the cost of the current behavior, the cost being higher when the reward is more distant, and the dopamine system reflects the current expected benefit. In a neuroeconomic framework, these two catecholamine systems, almost certainly evolved from a common ancestor, have diverged to represent costs and benefits, for NA and DA, respectively. We speculate that the interaction between these two neuromodulatory systems is critical to motivate value-based behavior, and intimate knowledge of the dynamic balance between them is required to model the motivation underlying higher reward seeking activity.

Monkeys Quickly Learn and Generalize Visual Categories without Lateral Prefrontal Cortex

Categorization is a basic mental process that helps individuals distinguish among groups of negative and positive objects, e.g., poisons and nutrients, or predators and prey. Monkey experiments have suggested that lateral prefrontal cortex (LPFC) participates in learning and processing visual categories. However, in humans category specific visual agnosia follows inferior temporal cortex but not LPFC damage. Here, we use a new behavioral approach to show that both normal monkeys and those with bilateral removal of LPFC learn and generalize perceptual categories of related visual stimuli rapidly without explicit instruction. These results strongly indicate that visual categorization occurs at some earlier stage of feed-forward processing, presumably in temporal cortex, without top-down information from LPFC.

Comment on Cohen et al: Neural Basis of the Set-Size Effect in Frontal Eye Field: Timing of Attention During Visual Search

to the editor: Distinguishing targets from distractors is crucial for goal-directed behavior and areas related to visual attention—including the lateral intraparietal area (LIP) and the frontal eye field (FEF)—have robust target-selective neural responses. The onset of significant target-

Influence of optimization constraints in uneven parallel bar dismount swing simulations

Forward dynamics simulations of a dismount preparation swing on the uneven parallel bars were optimized to investigate the sensitivity of dismount revolution potential to the maximum bar force before slipping, and to low-bar avoidance. All optimization constraints were classified as 1-anatomical/physiological; limiting maximum hand force on the high bar before slipping, joint ranges of motion and maximum torques, muscle activation/deactivation timing and 2-geometric; avoiding low-bar contact, and requiring minimum landing distance. The gymnast model included torso/head, arm and two leg segments connected by a planar rotating, compliant shoulder and frictionless ball-and-socket hip joints. Maximum shoulder and hip torques were measured as functions of joint angle and angular velocity. Motions were driven by scaling maximum torques by a joint torque activation function of time which approximated the average activation of all muscles crossing the joint causing extension/flexion, or adduction/abduction. Ten joint torque activation values, and bar release times were optimized to maximize dismount revolutions using the downhill simplex method. Low-bar avoidance and maximum bar-force constraints are necessary because they reduce dismount revolution potential. Compared with the no low-bar performance, optimally avoiding the low bar by piking and straddling (abducting) the hips reduces dismount revolutions by 1.8%. Using previously reported experimentally measured peak uneven bar-force values of 3.6 and 4.0 body weight (BW) as optimization constraints, 1.40 and 1.55 revolutions with the body extended and arms overhead were possible, respectively. The bar-force constraint is not active if larger than 6.9 BW, and instead performances are limited only by maximum shoulder and hip torques. Bar forces accelerate the mass center (CM) when performing muscular work to flex/extend the joints, and increase gymnast mechanical energy. Therefore, the bar-force constraint inherently limits performance by limiting the ability to do work and reducing system energy at bar release.

Trial Outcome and Associative Learning Signals in the Monkey Hippocampus

In tasks of associative learning, animals establish new links between unrelated items by using information about trial outcome to strengthen correct/rewarded associations and modify incorrect/unrewarded ones. To study how hippocampal neurons convey information about reward and trial outcome during new associative learning, we recorded hippocampal neurons as monkeys learned novel object-place associations. A large population of hippocampal neurons (50%) signaled trial outcome by differentiating between correct and error trials during the period after the behavioral response. About half these cells increased their activity following correct trials (correct up cells) while the remaining half fired more following error trials (error up cells). Moreover, correct up cells, but not error up cells, conveyed information about learning by increasing their stimulus-selective response properties with behavioral learning. These findings suggest that information about successful trial outcome conveyed by correct up cells may influence new associative learning through changes in the cell's stimulus-selective response properties.

Early Stages of Melody Processing: Stimulus-Sequence and Task-Dependent Neuronal Activity in Monkey Auditory Cortical Fields A1 and R

To explore the effects of acoustic and behavioral context on neuronal responses in the core of auditory cortex (fields A1 and R), two monkeys were trained on a go/no-go discrimination task in which they learned to respond selectively to a four-note target (S+) melody and withhold response to a variety of other nontarget (S-) sounds. We analyzed evoked activity from 683 units in A1/R of the trained monkeys during task performance and from 125 units in A1/R of two naive monkeys. We characterized two broad classes of neural activity that were modulated by task performance. Class I consisted of tone-sequence-sensitive enhancement and suppression responses. Enhanced or suppressed responses to specific tonal components of the S+ melody were frequently observed in trained monkeys, but enhanced responses were rarely seen in naive monkeys. Both facilitatory and suppressive responses in the trained monkeys showed a temporal pattern different from that observed in naive monkeys. Class II consisted of nonacoustic activity, characterized by a task-related component that correlated with bar release, the behavioral response leading to reward. We observed a significantly higher percentage of both Class I and Class II neurons in field R than in A1. Class I responses may help encode a long-term representation of the behaviorally salient target melody. Class II activity may reflect a variety of nonacoustic influences, such as attention, reward expectancy, somatosensory inputs, and/or motor set and may help link auditory perception and behavioral response. Both types of neuronal activity are likely to contribute to the performance of the auditory task.

Top–Down Attentional Deficits in Macaques with Lesions of Lateral Prefrontal Cortex

Brain imaging, electrical stimulation, and neurophysiological studies have all implicated the prefrontal cortex (PFC) in the top-down control of attention. Specifically, feedback from PFC has been proposed to bias activity in visual cortex in favor of attended stimuli over irrelevant distracters. To identify which attentional functions are critically dependent on PFC, we removed PFC unilaterally in combination with transection of the corpus callosum and anterior commissure in two macaques. In such a preparation, the ipsilesional hemisphere is deprived of top-down feedback from PFC to visual cortex, and the contralesional hemisphere can serve as an intact normal control. Monkeys were trained to fixate a central cue and discriminate the orientation of a colored target grating presented among colored distracter gratings in either the hemifield affected by the PFC lesion or the normal control hemifield. Locations of the targets and distracters were varied, and the color of the central cue specified the color of the target on each trial. The behavioral response was a bar release, and thus attentional impairments could be distinguished from impaired oculomotor control. When the cue was held constant for many trials, task performance in the affected hemifield was nearly normal. However, the monkeys were severely impaired when the cue was switched frequently across trials. The monkeys were unimpaired in a pop-out task with changing targets that did not require top-down attentional control. The PFC thus appears to play a critical role in the ability to flexibly reallocate attention on the basis of changing task demands.

Dual Time Scales for Categorical Decision Making in Auditory Cortex

Category formation allows us to group perceptual objects into meaningful classes and is fundamental to cognition. Categories can be derived from similarity relationships of object features by using prototypes or multiple exemplars, or from abstract relationships of features and rules . A variety of brain areas have been implicated in categorization processes, but mechanistic insights on the single-cell and local-network level are still rare and limited to the matching of individual objects to categories . For directional categorization of tone steps, as in melody recognition , abstract relationships between sequential events (higher or lower in frequency) have to be formed. To explore the neuronal mechanisms of this categorical identification of step direction, we trained monkeys for more than two years on a contour-discrimination task with multiple tone sequences. In the auditory cortex of these highly trained monkeys, we identified two interrelated types of neuronal firing: Increased phasic responses to tones categorically represented the reward-predicting downward frequency steps and not upward steps; subsequently, slow modulations of tonic firing predicted the behavioral decisions of the monkeys, including errors. Our results on neuronal mechanisms of categorical stimulus identification and of decision making attribute a cognitive role to auditory cortex, in addition to its role in signal processing.