345 research outputs found
Cannabinoid Receptor Involvement in Stress-Induced Cocaine Reinstatement: Potential Interaction with Noradrenergic Pathways
This study examined the role of endocannabinoid signaling in stress-induced reinstatement of cocaine seeking and explored the interaction between noradrenergic and endocannabinergic systems in the process. A well-validated preclinical model for human relapse, the rodent conditioned place preference assay, was used. Cocaine-induced place preference was established in C57BL/6 mice using injections of 15 mg/kg cocaine. Following extinction of preference for the cocaine-paired environment, reinstatement of place preference was determined following 6 min of swim stress or cocaine injection (15 mg/kg, i.p.). The role of endocannabinoid signaling was studied using the cannabinoid antagonist AM-251 (3 mg/kg, i.p.). Another cohort of mice was tested for reinstatement following administration of the cannabinoid agonist CP 55,940 (10, 20, or 40 μg/kg, i.p.). The alpha-2 adrenergic antagonist BRL-44408 (5 mg/kg, i.p.) with or without CP 55,940 (20 μg/kg) was administered to a third group of mice. We found that: (1) AM-251 blocked forced swim-induced, but not cocaine-induced, reinstatement of cocaine-seeking behavior; (2) the cannabinoid agonist CP 55,940 did not reinstate cocaine-seeking behavior when administered alone but did synergize with a non-reinstating dose of the alpha-2 adrenergic antagonist BRL-44408 to cause reinstatement. These results are consistent with the hypothesis that stress exposure triggers the endogenous activation of CB1 receptors and that activation of the endocannabinoid system is required for the stress-induced relapse of the mice to cocaine seeking. Further, the data suggest that the endocannabinoid system interacts with noradrenergic mechanisms to influence stress-induced reinstatement of cocaine-seeking behavior
A Statistical Analysis of STEVE
There has been an exciting recent development in auroral research associated with the discovery of a new subauroral phenomenon called STEVE (Strong Thermal Emission Velocity Enhancement). Although STEVE has been documented by amateur night sky watchers for decades, it is as yet an unidentified upper atmosphere phenomenon. Observed first by amateur auroral photographers, STEVE appears as a narrow luminous structure across the night sky over thousands of kilometers in the east‐west direction. In this paper, we present the first statistical analysis of the properties of 28 STEVE events identified using Time History of Events and Macroscale Interactions during Substorms (THEMIS) all‐sky imager and the Redline Emission Geospace Observatory (REGO) database. We find that STEVE occurs about 1 hr after substorm onset at the end of a prolonged expansion phase. On average, the AL index magnitude is larger and the expansion phase has a longer duration for STEVE events compared to subauroral ion drifts or substorms. The average duration for STEVE is about 1 hr, and its latitudinal width is ~20 km, which corresponds to ~¼ of the width of narrow auroral structures like streamers. STEVE typically has an equatorward displacement from its initial location of about 50 km and a longitudinal extent of 2,145 km
Real-time full bandwidth measurement of spectral noise in supercontinuum generation
The ability to measure real-time fluctuations of ultrashort pulses
propagating in optical fiber has provided significant insights into fundamental
dynamical effects such as modulation instability and the formation of
frequency-shifting rogue wave solitons. We report here a detailed study of
real-time fluctuations across the full bandwidth of a fiber supercontinuum
which directly reveals the significant variation in measured noise statistics
across the spectrum, and which allows us to study correlations between widely
separated spectral components. For two different propagation distances
corresponding to the onset phase of spectral broadening and the fully-developed
supercontinuum, we measure real time noise across the supercontinuum bandwidth,
and we quantify the supercontinuum noise using statistical higher-order moments
and a frequency-dependent intensity correlation map. We identify correlated
spectral regions within the supercontinuum associated with simultaneous
sideband generation, as well as signatures of pump depletion and soliton-like
pump dynamics. Experimental results are in excellent agreement with
simulations
The 17 March 2013 storm: Synergy of observations related to electric field modes and their ionospheric and magnetospheric Effects
The main phase of the 17 March 2013 storm had excellent coverage from groundâ based instruments and from lowâ and highâ altitude spacecraft, allowing for evaluation of the relations between major storm time phenomena that are often considered separately. The shock impact with its concurrent southward interplanetary magnetic field (IMF) immediately drove dramatic poleward expansion of the poleward boundary of the auroral oval (implying strong nightside reconnection), strong auroral activity, and strong penetrating midlatitude convection and ionospheric currents. This was followed by periods of southward IMF driving of electric fields that were at first relatively smooth as often employed in storm modeling but then became extremely bursty and structured associated with equatorward extending auroral streamers. The auroral oval did not expand much further poleward during these two latter periods, suggesting a lower overall nightside reconnection rate than that during the first period and approximate balance with dayside reconnection. Characteristics of these three modes of driving were reflected in horizontal and fieldâ aligned currents. Equatorward expansion of the auroral oval occurred predominantly during the structured convection mode, when electric fields became extremely bursty. The period of this third mode also approximately corresponded to the time of largest equatorward motion of the ionospheric trough, of apparent transport of high total electron content (TEC) features into the auroral oval from the polar cap, and of largest earthward injection of ions and electrons into the ring current. The enhanced responses of the aurora, currents, TEC, and the ring current indicate a common driving of all these storm time features during the bursty convection mode period.Key PointsStorm had excellent ground/space data coverage, allowing evaluation of relations between major storm phenomena often considered separatelyIdentified three southward IMF electric fields driving modes that were reflected in the aurora and ionospheric and fieldâ aligned currentsThe third mode was extremely bursty, giving common driving of auroral and current structures, TEC changes, and ring current injectionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135355/1/jgra53033_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/135355/2/jgra53033.pd
The NA48 LKr calorimeter digitizer electronics chain
The 13 500 channels of the NA48 liquid-krypton electromagnetic calorimeter readout electronics were put into operation in 1997. The digitizer electronics employs a new gain switching technique that expands the dynamic range of a standard 10-bit ADC to 14 bits at 40 MHz sampling rate employing a custom-developed integrated circuit (KRYPTON). The KRYPTON has been fabricated in 1.2 μm BiCMOS technology and was successfully developed together with industry on a short timescale. The performance and the experience from the first year of the operation of the liquid-krypton calorimeter electronics will also be briefly discussed
First observation of the KS->pi0 gamma gamma decay
Using the NA48 detector at the CERN SPS, 31 KS->pi0 gamma gamma candidates
with an estimated background of 13.7 +- 3.2 events have been observed. This
first observation leads to a branching ratio of BR(KS->pi0 gamma gamma) = (4.9
+- 1.6(stat) +- 0.9(syst)) x 10^-8 in agreement with Chiral Perturbation theory
predictions.Comment: 10 pages, 4 figures submitted to Phys. Lett.
The geometry of the magnetic field in the central molecular zone measured by PILOT
We present the first far infrared (FIR) dust emission polarization map covering the full extent of Milky Way’s central molecular zone (CMZ). The data, obtained with the PILOT balloon-borne experiment, covers the Galactic center region −2 ◦ < ` < 2◦, −4◦ < b < 3◦
at a wavelength of 240 µm and an angular resolution of 2.20
. From our measured dust polarization angles, we infer a magnetic field orientation projected onto the plane of the sky (POS) that is remarkably ordered over the full extent of the CMZ, with an average tilt angle of '22◦ clockwise with respect to the Galactic plane. Our results confirm previous claims that the field traced by dust polarized emission is oriented nearly orthogonally to the field traced by GHz radio synchrotron emission in the Galactic center region. The observed field structure is globally compatible with the latest Planck polarization data at 353 and 217 GHz. Upon subtraction of the extended emission in our data, the mean field orientation that we obtain shows good agreement with the mean field orientation measured at higher angular resolution by the JCMT within the 20 and 50 km s−1 molecular clouds. We find no evidence that the magnetic field orientation is related to the 100 pc twisted ring structure within the CMZ. The low polarization fraction in the Galactic center region measured with Planck at 353 GHz combined with a highly ordered projected field orientation is unusual. This feature actually extends to the whole inner Galactic plane. We propose that it could be caused by the increased number of turbulent cells for the long lines of sight towards the inner Galactic plane or to dust properties specific to the inner regions of the Galaxy. Assuming equipartition between magnetic pressure and ram pressure, we obtain magnetic field strength estimates of the order of 1 mG for several CMZ molecular clouds
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