An LED-based Flasher System for VERITAS

We describe a flasher system designed for use in monitoring the gains of the photomultiplier tubes used in the VERITAS gamma-ray telescopes. This system uses blue light-emitting diodes (LEDs) so it can be operated at much higher rates than a traditional laser-based system. Calibration information can be obtained with better statistical precision with reduced loss of observing time. The LEDs are also much less expensive than a laser. The design features of the new system are presented, along with measurements made with a prototype mounted on one of the VERITAS telescopes.Comment: Accepted for publication in Nuclear Instruments and Methods in Physics Research

Measurement of the parity violating 6S-7S transition amplitude in cesium achieved within 2 \times 10^{-13} atomic-unit accuracy by stimulated-emission detection

We exploit the process of asymmetry amplification by stimulated emission which provides an original method for parity violation (PV) measurements in a highly forbidden atomic transition. The method involves measurements of a chiral, transient, optical gain of a cesium vapor on the 7S-6P_{3/2} transition, probed after it is excited by an intense, linearly polarized, collinear laser, tuned to resonance for one hyperfine line of the forbidden 6S-7S transition in a longitudinal electric field. We report here a 3.5 fold increase, of the one-second-measurement sensitivity, and subsequent reduction by a factor of 3.5 of the statistical accuracy compared with our previous result [J. Gu\'ena et al., Phys. Rev. Lett. 90, 143001 (2003)]. Decisive improvements to the set-up include an increased repetition rate, better extinction of the probe beam at the end of the probe pulse and, for the first time to our knowledge, the following: a polarization-tilt magnifier, quasi-suppression of beam reflections at the cell windows, and a Cs cell with electrically conductive windows. We also present real-time tests of systematic effects, consistency checks on the data, as well as a 1% accurate measurement of the electric field seen by the atoms, from atomic signals. PV measurements performed in seven different vapor cells agree within the statistical error. Our present result is compatible with the more precise Boulder result within our present relative statistical accuracy of 2.6%, corresponding to a 2 \times 10^{-13} atomic-unit uncertainty in E_1^{pv}. Theoretical motivations for further measurements are emphasized and we give a brief overview of a recent proposal that would allow the uncertainty to be reduced to the 0.1% level by creating conditions where asymmetry amplification is much greater.Comment: Article 21 pages, 6 figures, 3 tables Typos, addition of few comments and little more data (1 week) leading to a slight reduction of the error bar Accepted for publication in Phys.Rev.

Double label autoradiography : an improvement

A convenient method for double-label autoradiography is described that uses an aqueous mountant, Gelutol (polyvinyl alcohol), which keeps the gelatin spacer in the final autoradiograph permanently swollen to a thickness of around 18 microns in contrast to its 5 microns thickness during exposure of the autoradiograph. This greatly improves optical discrimination between upper and lower layers without the loss of sensitivity or resolution that would result if a 18 microns spacer were used during exposure

Is there an integrative center in the vertebrate brain-stem? A robotic evaluation of a model of the reticular formation viewed as an action selection device

Neurobehavioral data from intact, decerebrate, and neonatal rats, suggests that the reticular formation provides a brainstem substrate for action selection in the vertebrate central nervous system. In this article, Kilmer, McCulloch and Blum’s (1969, 1997) landmark reticular formation model is described and re-evaluated, both in simulation and, for the first time, as a mobile robot controller. Particular model configurations are found to provide effective action selection mechanisms in a robot survival task using either simulated or physical robots. The model’s competence is dependent on the organization of afferents from model sensory systems, and a genetic algorithm search identified a class of afferent configurations which have long survival times. The results support our proposal that the reticular formation evolved to provide effective arbitration between innate behaviors and, with the forebrain basal ganglia, may constitute the integrative, ’centrencephalic’ core of vertebrate brain architecture. Additionally, the results demonstrate that the Kilmer et al. model provides an alternative form of robot controller to those usually considered in the adaptive behavior literature

Implementation of Critical Threshold Concept in Clinical Transplantation: A New Horizon in Distance Learning

While variations in medical practice are a norm and each patient poses a multitude of challenges, many clinicians are not comfortable in dealing with unexpected complex issues even though they may have enough knowledge as demonstrated by passing a number of tricky certifying (or exit) examinations. One reason for the lack of self-efficacy, even if being endowed with good knowledge, is that we are not good in learning from errors. A regular reflective practice offers superb learning opportunities when a clinician is “stuck in a mire”. Difficult clinical situations warrant a flexible and, at the same time, an evidence-based approach to ensure that crucial decision-making process is correct and efficient. Each clinical case offers a great opportunity to reinforce these “threshold concepts”, however, not everyone of us is “blessed” with these crucial not-so-difficult-to-acquire skills so necessary to be a life-long learner. The faculty of this course (a totally on-line MSc in Transplant Sciences) aims for unceasing engagement with students in order to facilitate them to negotiate through “stuck places” and “tricky bends” in their own work place. This course, not just meant for knowledge transfer, provides a platform that allows participants (the students and faculty) to learn from each other’s experience by using “e-blackboard”. The mainstay of this course are twofold: (a) Emphasis on achieving critical decision-making skills, (b) Regular feedback to allow reflective practice and, thereby, constantly learning from errors and reinforcing good practices. The aim of this article is to assess the performance of educators and how well the “ethos of critical threshold” has been accepted from the perspective of students. Methods: The critical thresholds of each chapter in 4 modules of this totally on-line course were defined to a razor-sharp precision. Learning objectives of learning activity were defined to achieve constructive alignment with critical threshold. We employed level 1, 2, 4 and 5 of Kirkpatrick pyramid, (a) for the evaluation of performance of educators of program, and (b) to evaluate the acceptance of this non-traditional format in clinical medicine education by postgraduate 80 students in 22 countries. Results: Students’ survey (Kirkpatrick level 1) was done only for module 1 of cohort 1 reported students’ satisfaction rate of 93%. Excluding a total of 12 drop-outs in 2 modules (n=10 in first cohort’s module 1, and n=2 in module 2), as many as 93% of students of first cohort passed module. Nine out of 60 registrants of module 1 in 2nd cohort took recess for one year requesting to join back as a part of 3rd cohort commencing one year later, all 51 who continued passed though 3 of them had to resit. All those who passed module 1 (both cohorts) and 2 (1st cohort) registered for their respective next module (return on investment Kirkpatrick level 5). Conclusion: For a successful model in distance learning in clinical transplantation it is imperative for the students to accomplish well defined “critical-decision making” skills. In order to learn critical thresholds, a regular feedback is integral to learning from reflective practice. This course equips the students to develop skills of negotiating “sticky mire”, as obvious from perceived high return of investment

Congratulations, It’s a Boy! Bench-Marking Children’s Perceptions of the Robokind Zeno-R25

This paper explores three fundamental attributes of the Robokind Zeno-R25 (its status as person or machine, its ‘gender’, and intensity of its simulated facial expressions) and their impact on children’s perceptions of the robot, using a one-sample study design. Results from a sample of 37 children indicate that the robot is perceived as being a mix of person and machine, but also strongly as a male figure. Children could label emotions of the robot’s simulated facial-expressions but perceived intensities of these expressions varied. The findings demonstrate the importance of establishing fundamentals in user views towards social robots in supporting advanced arguments of social human-robot interaction

Designing robot personalities for human-robot symbiotic interaction in an educational context

The Expressive Agents for Symbiotic Education and Learning project explores human-robot symbiotic interaction with the aim to understand the development of symbiosis over long-term tutoring interactions. The final EASEL system will be built upon the neurobiologically grounded architecture - Distributed Adaptive Control. In this paper, we present the design of an interaction scenario to support development of the DAC, in the context of a synthetic tutoring assistant. Our humanoid robot, capable of life-like simulated facial expressions, will interact with children in a public setting to teach them about exercise and energy. We discuss the range of measurements used to explore children’s responses during, and experiences of, interaction with a social, expressive robot

Preliminary evidence for human globus pallidus pars interna neurons signaling reward and sensory stimuli.

The globus pallidus pars interna (GPi) is a component of the basal ganglia, a network of subcortical nuclei that process motor, associative, and limbic information. While non-human primate studies have suggested a role for the GPi in non-motor functions, there have been no single-unit studies of non-motor electrophysiological behavior of human GPi neurons. We therefore sought to extend these findings by collecting single-unit recordings from awake patients during functional stereotactic neurosurgery targeting the GPi for deep brain stimulation. To assess cellular responses to non-motor information, patients performed a reward task where virtual money could be won, lost, or neither, depending on their performance while cellular activity was monitored. Changes in the firing rates of isolated GPi neurons after the presentation of reward-related stimuli were compared between different reward contingencies (win, loss, null). We observed neurons that modulated their firing rate significantly to the presentation of reward-related stimuli. We furthermore found neurons that responded to visual-stimuli more broadly. This is the first single-unit evidence of human GPi neurons carrying non-motor information. These results are broadly consistent with previous findings in the animal literature and suggest non-motor information may be represented in the single-unit activity of human GPi neurons.NAH is supported by a Unilever/Lipton Graduate Fellowship in Neuroscience and a University of Toronto Fellowship. WDH is supported by a CIHR operating grant (98006). VV is a Wellcome Trust (WT) intermediate Clinical Fellow (WT093705MA).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.neuroscience.2016.04.02