11,554 research outputs found
Heavy Baryons and electromagnetic decays
In this talk I review the theory of electromagnetic decays of the ground
state baryon multiplets with oneheavy quark, calculated using Heavy Hadron
Chiral Perturbation Theory. The M1 and E2 amplitudes for (S^{*}-> S gamma),
(S^{*} -> T gamma) and (S -> T gamma)are separately analyzed. All M1
transitions are calculated up to O(1/\Lambda_\chi^2). The E2 amplitudes
contribute at the same order for (S^{*}-> S gamma), while for (S^{*} -> T
gamma) they first appear at O(1/(m_Q \Lambda_\chi^2))and for (S -> T gamma) are
completely negligible. Once the loop contributions is considered, relations
among different decay amplitudes are derived. Furthermore, one can obtain an
absolute prediction for the widths of Xi^{0'(*)}_c-> Xi^{0}_c gamma and
Xi^{-'(*)}_b-> Xi^{-}_b gamma.Comment: Talk presented at 4^{th} International Conference Hyperons, Charm and
Beauty Hadrons Conference, Valencia June 200
Observing thermal Schwinger pair production
We study the possibility of observing Schwinger pair production enhanced by a thermal bath of photons. We consider the full range of temperatures and electric field intensities from pure Schwinger production to pure thermal production, and identify the most promising and interesting regimes. In particular, we identify temperatures of similar to 20 keV/k(B) and field intensities of similar to 10(23) W cm(-2) where pair production would be observable. In this case, the thermal enhancement over the Schwinger rate is exponentially large and due to effects which are not visible at any finite order in the loop expansion. Pair production in this regime can thus be described as more nonperturbative than the usual Schwinger process, which appears at one loop. Unfortunately, such high temperatures appear to be out of reach of foreseeable technologies, though nonthermal photon distributions with comparable energy densities are possible. We suggest the possibility that similar nonperturbative enhancements may extend out of equilibrium and propose an experimental scheme to test this.Peer reviewe
Ten Simple Rules for Reproducible Research in Jupyter Notebooks
Reproducibility of computational studies is a hallmark of scientific
methodology. It enables researchers to build with confidence on the methods and
findings of others, reuse and extend computational pipelines, and thereby drive
scientific progress. Since many experimental studies rely on computational
analyses, biologists need guidance on how to set up and document reproducible
data analyses or simulations.
In this paper, we address several questions about reproducibility. For
example, what are the technical and non-technical barriers to reproducible
computational studies? What opportunities and challenges do computational
notebooks offer to overcome some of these barriers? What tools are available
and how can they be used effectively?
We have developed a set of rules to serve as a guide to scientists with a
specific focus on computational notebook systems, such as Jupyter Notebooks,
which have become a tool of choice for many applications. Notebooks combine
detailed workflows with narrative text and visualization of results. Combined
with software repositories and open source licensing, notebooks are powerful
tools for transparent, collaborative, reproducible, and reusable data analyses
Heterogeneous Power-Splitting Based Two-Way DF Relaying with Non-Linear Energy Harvesting
Simultaneous wireless information and power transfer (SWIPT) has been
recognized as a promising approach to improving the performance of energy
constrained networks. In this paper, we investigate a SWIPT based three-step
two-way decode-and-forward (DF) relay network with a non-linear energy
harvester equipped at the relay. As most existing works require instantaneous
channel state information (CSI) while CSI is not fully utilized when designing
power splitting (PS) schemes, there exists an opportunity for enhancement by
exploiting CSI for PS design. To this end, we propose a novel heterogeneous PS
scheme, where the PS ratios are dynamically changed according to instantaneous
channel gains. In particular, we derive the closed-form expressions of the
optimal PS ratios to maximize the capacity of the investigated network and
analyze the outage probability with the optimal dynamic PS ratios based on the
non-linear energy harvesting (EH) model. The results provide valuable insights
into the effect of various system parameters, such as transmit power of the
source, source transmission rate, and source to relay distance on the
performance of the investigated network. The results show that our proposed PS
scheme outperforms the existing schemes.Comment: This article has been accepted by IEEE GLOBECOM201
Effect of long-term cannabidiol on learning and anxiety in a female Alzheimer’s disease mouse model
Cannabidiol is a promising potential therapeutic for neurodegenerative diseases, including Alzheimer’s disease (AD). Our laboratory has shown that oral CBD treatment prevents cognitive impairment in a male genetic mouse model of AD, the amyloid precursor protein 1 x presenilin 1 hemizygous (APPxPS1) mouse. However, as sex differences are evident in clinical populations and in AD mouse models, we tested the preventive potential of CBD therapy in female APPxPS1 mice. In this study, 2.5-month-old female wildtype-like (WT) and APPxPS1 mice were fed 20Â mg/kg CBD or a vehicle via gel pellets daily for 8 months and tested at 10.5Â months in behavioural paradigms relevant to cognition (fear conditioning, FC; cheeseboard, CB; and novel object recognition test, NORT) and anxiety-like behaviours (elevated plus maze, EPM). In the CB, CBD reduced latencies to find a food reward in APPxPS1 mice, compared to vehicle-treated APPxPS1 controls, and this treatment effect was not evident in WT mice. In addition, CBD also increased speed early in the acquisition of the CB task in APPxPS1 mice. In the EPM, CBD increased locomotion in APPxPS1 mice but not in WT mice, with no effects of CBD on anxiety-like behaviour. CBD had limited effects on the expression of fear memory. These results indicate preventive CBD treatment can have a moderate spatial learning-enhancing effect in a female amyloid-β-based AD mouse model. This suggests CBD may have some preventive therapeutic potential in female familial AD patients
Thickness and Conductivity of Metallic Layers from Pulsed Eddy Current Measurements
Coatings and surface treatments find a wide range of technological applications; they can provide wear resistance, oxidation and corrosion protection, electrical contact or isolation and thermal insulation. Consequently, the ability to determine the thickness of coated metals is important for both process control and in-service inspection of parts. Presently ultrasonic, thermal, and eddy current inspection methods are used, depending on the circumstances. A number of commercial instruments for determining the thickness of nonconducting coatings on metal substrates are based on the fact that the impedance change of the coil decreases exponentially with the distance of the coil from the metal (the lift-off effect). However, these instruments are not suitable for determining the thickness of metal layers on conducting substrates
Dynamic Path Planning of a mobile robot adopting a costmap layer approach in ROS2
Mobile robots can highly contribute to achieve the production flexibility envisaged by the Industry 4.0 paradigm, provided that they show an adequate level of autonomy to operate in a typical industrial environment, in which the presence of both static and dynamic obstacles must be managed. Robot Operating System (ROS) is a well known open-source platform for the development of robotic applications, recently updated to the enhanced ROS2 version, including a navigation stack (Nav2) providing most, but not all the capabilities required to a mobile robot operating in an industrial environment. In particular, it does not embed a strategy for dynamic obstacle handling. Aim of this paper is to enhance Nav2 through the development of a Dynamic Obstacle Layer, as a plug and play solution suitable for the integration of the dynamic obstacle information acquired by a generic 2D LiDAR sensor. The effectiveness of the proposed solution is validated through a campaign of simulation tests, carried out in Webots for a TurtleBot3 burger robot, equipped with a RPLIDAR A3 LiDAR sensor
Spatiotemporal regulation of the cough motor pattern
The purpose of this study was to identify the spatiotemporal determinants of the cough motor pattern. We speculated that the spatial and temporal characteristics of the cough motor pattern would be regulated separately. Electromyograms (EMG) of abdominal muscles (ABD, rectus abdominis or transversus abdominis), and parasternal muscles (PS) were recorded in anesthetized cats. Repetitive coughing was produced by mechanical stimulation of the lumen of the intrathoracic trachea. Cough inspiratory (CTI) and expiratory (CTE) durations were obtained from the PS EMG. The ABD EMG burst was confined to the early part of CTE and was followed by a quiescent period of varying duration. As such, CTE was divided into two segments with CTE1 defined as the duration of the ABD EMG burst and CTE2 defined as the period of little or no EMG activity in the ABD EMG. Total cough cycle duration (CTTOT) was strongly correlated with CTE2 (r2>0.8), weakly correlated with CTI (r2<0.3), and not correlated with CTE1 (r2<0.2). There was no significant relationship between CTI and CTE1 or CTE2. The magnitudes of inspiratory and expiratory motor drive during cough were only weakly correlated with each other (r2<0.36) and were not correlated with the duration of any phase of cough. The results support: a) separate regulation of CTI and CTE, b) two distinct subphases of CTE (CTE1 and CTE2), c) the duration of CTE2 is a primary determinant of CTTOT, and d) separate regulation of the magnitude and temporal features of the cough motor pattern
- …