Early molecular layer interneuron hyperactivity triggers Purkinje neuron degeneration in SCA1.

Toxic proteinaceous deposits and alterations in excitability and activity levels characterize vulnerable neuronal populations in neurodegenerative diseases. Using in vivo two-photon imaging in behaving spinocerebellar ataxia type 1 (Sca1) mice, wherein Purkinje neurons (PNs) degenerate, we identify an inhibitory circuit element (molecular layer interneurons [MLINs]) that becomes prematurely hyperexcitable, compromising sensorimotor signals in the cerebellum at early stages. Mutant MLINs express abnormally elevated parvalbumin, harbor high excitatory-to-inhibitory synaptic density, and display more numerous synaptic connections on PNs, indicating an excitation/inhibition imbalance. Chemogenetic inhibition of hyperexcitable MLINs normalizes parvalbumin expression and restores calcium signaling in Sca1 PNs. Chronic inhibition of mutant MLINs delayed PN degeneration, reduced pathology, and ameliorated motor deficits in Sca1 mice. Conserved proteomic signature of Sca1 MLINs, shared with human SCA1 interneurons, involved the higher expression of FRRS1L, implicated in AMPA receptor trafficking. We thus propose that circuit-level deficits upstream of PNs are one of the main disease triggers in SCA1

Hybrid imaging and timing ps laser excitation diagnostics for pulsed antihydrogen production

open48siIn this work we present a hybrid detection method providing simultaneous imaging and timing information suitable for fully monitoring positronium (Ps) formation, its laser excitation, and its spatial propagation for the first trials of pulsed antihydrogen (H) production through a charge-exchange reaction with trapped antiprotons (p). This combined method, based on the synchronous acquisition of an EJ-200 scintillation detector and a microchannel plate (MCP) detector with a dual readout (phosphor screen image and electrical pick-up signal), allows all relevant events in the experiment to be accurately determined in time while allowing high resolution images of e+ from Ps laser photodissociations to be acquired. The timing calibration process of the two detectors discussed in details as well as the future perspectives opened by this method.openCaravita R.; Antonello M.; Belov A.; Bonomi G.; Brusa R.S.; Caccia M.; Camper A.; Castelli F.; Comparat D.; Consolati G.; Demetrio A.; Di Noto L.; Doser M.; Fani M.; Ferragut R.; Gerber S.; Giammarchi M.; Gligorova A.; Gloggler L.T.; Guatieri F.; Haider S.; Hinterberger A.; Khalidova O.; Krasnicky D.; Lagomarsino V.; Malbrunot C.; Mariazzi S.; Matveev V.; Muller S.R.; Nebbia G.; Nedelec P.; Oberthaler M.; Oswald E.; Pagano D.; Penasa L.; Petracek V.; Prelz F.; Rienacker B.; Rohne O.M.; Rotondi A.; Sandaker H.; Santoro R.; Testera G.; Tietje I.; Toso V.; Wolz T.; Zimmer C.; Zurlo N.Caravita, R.; Antonello, M.; Belov, A.; Bonomi, G.; Brusa, R. S.; Caccia, M.; Camper, A.; Castelli, F.; Comparat, D.; Consolati, G.; Demetrio, A.; Di Noto, L.; Doser, M.; Fani, M.; Ferragut, R.; Gerber, S.; Giammarchi, M.; Gligorova, A.; Gloggler, L. T.; Guatieri, F.; Haider, S.; Hinterberger, A.; Khalidova, O.; Krasnicky, D.; Lagomarsino, V.; Malbrunot, C.; Mariazzi, S.; Matveev, V.; Muller, S. R.; Nebbia, G.; Nedelec, P.; Oberthaler, M.; Oswald, E.; Pagano, D.; Penasa, L.; Petracek, V.; Prelz, F.; Rienacker, B.; Rohne, O. M.; Rotondi, A.; Sandaker, H.; Santoro, R.; Testera, G.; Tietje, I.; Toso, V.; Wolz, T.; Zimmer, C.; Zurlo, N

Velocity-selected production of 2S3 metastable positronium

Positronium in the 2 3 S metastable state exhibits a low electrical polarizability and a long lifetime (1140 ns), making it a promising candidate for interferometry experiments with a neutral matter-antimatter system. In the present work, 2 3 S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 3 3 P level populated with a 205-nm UV laser pulse. Thanks to the short temporal length of the pulse, 1.5 ns full width at half maximum, different velocity populations of a positronium cloud emitted from a nanochanneled positron-positronium converter were selected by delaying the excitation pulse with respect to the production instant. 2 3 S positronium atoms with velocity tuned between 7 7 10 4 ms 121 and 10 7 10 4 ms 121 were thus produced. Depending on the selected velocity, a 2 3 S production efficiency ranging from 3c0.8% to 3c1.7%, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the 3 3 P-2 3 S spontaneous decay of (9.7 \ub1 2.7)%. The present velocity selection technique could allow one to produce an almost monochromatic beam of 3c1 7 10 3 2 3 S atoms with a velocity spread of <10 4 ms 121 and an angular divergence of 3c50 mrad

Development of a detector for inertial sensing of positronium at AEgIS (CERN)

The primary goal of the AEgIS collaboration at CERN is to measure the gravitational acceleration on neutral antimatter. Positronium (Ps), the bound state of an electron and a positron, is a suitable candidate for a force-sensitive inertial measurement by means of deflectometry/interferometry. In order to conduct such an experiment, the impact position and time of arrival of Ps atoms at the detector must be detected simultaneously. The detection of a low-velocity Ps beam with a spatial resolution of (88 ± 5) μm was previously demonstrated [1]. Based on the methodology employed in [1] and [2], a hybrid imaging/timing detector with increased spatial resolution of about 10 μm was developed. The performance of a prototype was tested with a positron beam. The concept of the detector and first results are presented

Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts

A cradle-to-grave life cycle assessment (LCA) is performed to compare nanosilver T-shirts with conventional T-shirts with and without biocidal treatment. For nanosilver production and textile incorporation, we investigate two processes: flame spray pyrolysis (FSP) and plasma polymerization with silver co-sputtering (PlaSpu). Prospective environmental impacts due to increased nanosilver T-shirt commercialization are estimated with six scenarios. Results show significant differences in environmental burdens between nanoparticle production technologies: The "cradle-to-gate" climate footprint of the production of a nanosilver T-shirt is 2.70 kg of CO2-equiv (FSP) and 7.67-166 kg of CO2-equiv (PlaSpu, varying maturity stages). Production of conventional T-shirts with and without the biocide triclosan has emissions of 2.55 kg of CO2-equiv (contribution from triclosan insignificant). Consumer behavior considerably affects the environmental impacts during the use phase. Lower washing frequencies can compensate for the increased climate footprint of FSP nanosilver T-shirt production. The toxic releases from washing and disposal in the life cycle of T-shirts appear to be of minor relevance. By contrast, the production phase may be rather significant due to toxic silver emissions at the mining site if high silver quantities are require

AEg̅IS latest results

The validity of the Weak Equivalence Principle (WEP) as predicted by General Relativity has been tested up to astounding precision using ordinary matter. The lack hitherto of a stable source of a probe being at the same time electrically neutral, cold and stable enough to be measured has prevented highaccuracy testing of the WEP on anti-matter. The AEg̅IS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment located at CERN's AD (Antiproton Decelerator) facility aims at producing such a probe in the form of a pulsed beam of cold anti-hydrogen, and at measuring by means of a moiré deflectometer the gravitational force that Earth's mass exerts on it. Low temperature and abundance of the H̅ are paramount to attain a high precision measurement. A technique employing a charge-exchange reaction between antiprotons coming from the AD and excited positronium atoms is being developed at AEg̅IS and will be presented hereafter, alongside an overview of the experimental apparatus and the current status of the experimen

Techniques for production and detection of 23S positronium

In this work, we show recent measurements of 23S long-lived positronium production via spontaneous decay from the 33P level. The possibility to tune the velocity of the 23S positronium, excited following this scheme, is presented. In the light of these results, we discuss the use of the 33P→23S transition to realize a monochromatic pulsed 23S positronium beam with low angular divergence. Preliminary tests of 23S beam production are presented. The possibility to overcome the natural 33P→23S branching ratio via stimulated emission, and thus increasing the intensity of the 23S source, is also shown. A position-sensitive detector for a pulsed beam of positronium, with spatial resolution of ≈ 90 μm, is finally described in view of its possible application for the spatial characterization of the 23S beam

The AEgIS experiment at CERN: Measuring antihydrogen free-fall in earth's gravitational field to test WEP with antimatter

The AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment is designed with the objective to test the weak equivalence principle with antimatter by studying the free fall of antihydrogen in the Earth's gravitational field. A pulsed cold beam of antihydrogen will be produced by charge exchange between cold Ps excited in Rydberg state and cold antiprotons. Finally the free fall will be measured by a classical moir\ue9 deflectometer. The apparatus being assembled at the Antiproton Decelerator at CERN will be described, then the advancements of the experiment will be reported: positrons and antiprotons trapping measurements, Ps two-step excitation and a test-measurement of antiprotons deflection with a small scale moir\ue9 deflectometer