Models that postulate the existence of hidden sectors address contemporary questions, such as the source of baryogenesis and the nature of dark matter. Neutron-to-hidden-neutron oscillations are ...among the possible mixing processes and have been tested with ultracold neutron storage and passing-through-wall experiments to set constraints on the oscillation period τ_{nn^{'}}. These searches probe the oscillations as a function of the mass splitting due to the neutron-hidden-neutron energy degeneracy. In this work, we present a new limit derived from neutron disappearance in ultracold neutron beam experiments. The overall limit, given by τ_{nn^{'}}>1 s for |δm|∈2,69 peV(95.45% C.L.), covers the yet unexplored intermediate mass-splitting range and contributes to the ongoing research on hidden sectors.
In social insects, grooming is considered as a behavioral defense against pathogen and parasite infections since it contributes to remove microbes from their cuticle. However, stimuli which trigger ...this behavior are not well characterized yet. We examined if activating contact chemoreceptive sensilla could trigger grooming activities in Drosophila melanogaster. We monitored the grooming responses of decapitated flies to compounds known to activate the immune system, e.g., dead Escherichia coli (Ec) and lipopolysaccharides (LPS), and to tastants such as quinine, sucrose, and salt. LPS, quinine, and Ec were quite effective in triggering grooming movements when touching the distal border of the wings and the legs, while sucrose had no effect. Contact chemoreceptors are necessary and sufficient to elicit such responses, as grooming could not be elicited by LPS in poxn mutants deprived of external taste sensilla, and as grooming was elicited by light when a channel rhodopsin receptor was expressed in bitter-sensitive cells expressing Gr33a. Contact chemoreceptors distributed along the distal border of the wings respond to these tastants by an increased spiking activity, in response to quinine, Ec, LPS, sucrose, and KCl. These results demonstrate for the first time that bacterial compounds trigger grooming activities in D. melanogaster, and indicate that contact chemoreceptors located on the wings participate in the detection of such chemicals.
An upgrade of the Near Detector of the T2K long baseline neutrino oscillation experiment, ND280, has been proposed. This upgrade will include two new Time Projection Chambers, each equipped with 16 ...resistive Micromegas modules for gas amplification. A first prototype of resistive Micromegas has been designed, built, installed in the HARP field cage, and exposed to a beam of charged particles at CERN. The data have been used to characterize the performances of the resistive Micromegas module. A spatial resolution of 300 μm and a deposited energy resolution of 9% were observed for horizontal electrons crossing the TPCs at 30 cm from the anode. Such performances fully satisfy the requirements for the upgrade of the ND280 TPC.
We present an apparatus for detection of cyclotron radiation yielding a frequency-based β± kinetic energy determination in the 5 keV to 2.1 MeV range, characteristic of nuclear β decays. The ...cyclotron frequency of the radiating β particles in a magnetic field is used to determine the β energy precisely. Our work establishes the foundation to apply the cyclotron radiation emission spectroscopy (CRES) technique, developed by the Project 8 Collaboration, far beyond the 18-keV tritium endpoint region. We report initial measurements of β–’s from 6He and β+’s from 19Ne decays to demonstrate the broadband response of our detection system and assess potential systematic uncertainties for β spectroscopy over the full (MeV) energy range. To our knowledge, this is the first direct observation of cyclotron radiation from individual highly relativistic β’s in a waveguide. Furthermore, this work establishes the application of CRES to a variety of nuclei, opening its reach to searches for new physics beyond the TeV scale via precision β-decay measurements.
An upgrade of the near detector of the T2K long baseline neutrino oscillation experiment is currently being conducted. This upgrade will include two new Time Projection Chambers, each equipped with ...16 charge readout resistive Micromegas modules.
A procedure to validate the performance of the detectors at different stages of production has been developed and implemented to ensure a proper and reliable operation of the detectors once installed. A dedicated X-ray test bench is used to characterize the detectors by scanning each pad individually and to precisely measure the uniformity of the gain and the deposited energy resolution over the pad plane. An energy resolution of about 10% is obtained.
A detailed physical model has been developed to describe the charge dispersion phenomena in the resistive Micromegas anode. The detailed physical description includes initial ionization, electron drift, diffusion effects and the readout electronics effects. The model provides an excellent characterization of the charge spreading of the experimental measurements and allowed the simultaneous extraction of gain and charge spreading information of the modules.
The cyclotron radiation emission spectroscopy (CRES) technique pioneered by Project 8 measures electromagnetic radiation from individual electrons gyrating in a background magnetic field to construct ...a highly precise energy spectrum for beta decay studies and other applications. The detector, magnetic trap geometry and electron dynamics give rise to a multitude of complex electron signal structures which carry information about distinguishing physical traits. With machine learning models, we develop a scheme based on these traits to analyze and classify CRES signals. Proper understanding and use of these traits will be instrumental to improve cyclotron frequency reconstruction and boost the potential of Project 8 to achieve world-leading sensitivity on the tritium endpoint measurement in the future.
Abstract
Cyclotron radiation emission spectroscopy (CRES) is a modern approach for determining charged particle energies via high-precision frequency measurements of the emitted cyclotron radiation. ...For CRES experiments with gas within the fiducial volume, signal and noise dynamics can be modelled by a hidden Markov model. We introduce a novel application of the Viterbi algorithm in order to derive informational limits on the optimal detection of cyclotron radiation signals in this class of gas-filled CRES experiments, thereby providing concrete limits from which future reconstruction algorithms, as well as detector designs, can be constrained. The validity of the resultant decision rules is confirmed using both Monte Carlo and Project 8 data.
The Locust simulation package is a new C++ software tool developed to simulate the measurement of time-varying electromagnetic fields using RF detection techniques. Modularity and flexibility allow ...for arbitrary input signals, while concurrently supporting tight integration with physics-based simulations as input. External signals driven by the Kassiopeia particle tracking package are discussed, demonstrating conditional feedback between Locust and Kassiopeia during software execution. An application of the simulation to the Project 8 experiment is described. Locust is publicly available at https://github.com/project8/locust_mc.
Abstract The objective of the cyclotron radiation emission spectroscopy (CRES) technology is to build precise particle energy spectra. This is achieved by identifying the start frequencies of charged ...particle trajectories which, when exposed to an external magnetic field, leave semi-linear profiles (called tracks) in the time–frequency plane. Due to the need for excellent instrumental energy resolution in application, highly efficient and accurate track reconstruction methods are desired. Deep learning convolutional neural networks (CNNs) - particularly suited to deal with information-sparse data and which offer precise foreground localization—may be utilized to extract track properties from measured CRES signals (called events) with relative computational ease. In this work, we develop a novel machine learning based model which operates a CNN and a support vector machine in tandem to perform this reconstruction. A primary application of our method is shown on simulated CRES signals which mimic those of the Project 8 experiment—a novel effort to extract the unknown absolute neutrino mass value from a precise measurement of tritium β − -decay energy spectrum. When compared to a point-clustering based technique used as a baseline, we show a relative gain of 24.1% in event reconstruction efficiency and comparable performance in accuracy of track parameter reconstruction.
50 nuances de violet Leprince, M.; Guigue, M.; Scarfogliere, V. ...
La revue de medecine interne,
June 2017, 2017-06-00, Letnik:
38
Journal Article
Recenzirano
Le syndrome des urines violettes ou « Purple Urine Bag Syndrome » est une situation clinique rare, observée le plus souvent chez des femmes âgées de plus de 80 ans, porteuses d’une sonde urinaire à ...demeure.
Nous rapportons le cas d’une patiente âgée de 95 ans, hospitalisée pour maintien à domicile impossible dans un contexte de perte d’autonomie secondaire à une ostéonécrose aseptique de la tête fémorale droite. Son état clinique a nécessité la pose d’une sonde urinaire à demeure. Elle est hypertendue traitée par lercanidipine 10 mg par jour, ne présente pas de diabète. À l’admission, la patiente était apyrétique et ne décrivait pas de plainte fonctionnelle particulière. Ses urines étaient claires. Après 48heures d’hospitalisation, alors que son état clinique demeurait inchangé, une coloration violette du tuyau et du sac collecteur est apparue. Son alimentation, dépourvue de betteraves et de mûres, ainsi que son traitement ne pouvaient expliquer cette coloration. La bandelette urinaire retrouvait un pH alcalin, l’examen cytobactériologique urinaire mettait en évidence une flore polymicrobienne (106) avec une leucocyturie de 1000/mm3, sans hématurie. Biologiquement, il n’y avait pas de syndrome inflammatoire, pas d’insuffisance rénale, ni hépatique et pas d’hémolyse. Le changement de la sonde urinaire n’a pas permis de normaliser la coloration des urines. Par contre, elles retrouvaient leur coloration habituelle après recueil dans un tubesec.
Le diagnostic de Purple Urine Bag Syndrome (PUBS) a été porté et a été confirmé par le dosage élevé du 3-indoxyl sulfate urinaire. La physiopathologie de ce syndrome implique la dégradation intestinale du tryptophane (acide aminé alimentaire) en indole. Il est transformé par le foie en 3-indoxyl sulfate, métabolite qui se retrouve en forte concentration dans les urines. L’indoxyl sulfate en présence d’enzymes bactériennes, les sulfatases, se transforme en indoxyl, qui devient de l’indigo (pigment bleu) dans un milieu alcalin et les milieux pauvres en oxygène favorisent la transformation en indirubine (pigment rouge). La coloration violette est obtenue par l’interaction entre ces pigments avec le polychlorure de vinyl du tuyau et sac collecteur des urines. Il est à noter que le pH urinaire et la teneur en oxygène des urines peuvent faire varier la couleur de la paroi du tube collecteur et du sac des urines (nuances de violet). Les facteurs prédisposant sont le sexe féminin, l’âge supérieur à 80 ans, la démence, la constipation, le sondage urinaire d’une durée supérieure à 12jours, les infections urinaires par des germes possédant des sulfatases (Providencia stuartii, Klebiella pneumoniae, Enterobacter agglomerans, Pseudomonas aeruginosa, Proteus mirabillis et E. coli) et le pH alcalin urinaire.
Ce syndrome est sans aucune conséquence clinique et doit être connu afin de ne pas inquiéter le personnel soignant.
PDF
