Detection of Volcanic Plumes by GPS: the 23 November 2013 Episode on Mt. Etna

The detection of volcanic plumes produced during explosive eruptions is important to improve our under- standing on dispersal processes and reduce risks to aviation operations. The ability of Global Position-ing System (GPS) to retrieve volcanic plumes is one of the new challenges of the last years in volcanic plume de - tection. In this work, we analyze the Signal to Noise Ratio (SNR) data from 21 permanent stations of the GPS network of the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo, that are located on the Mt. Etna (Italy) flanks. Being one of the most explosive events since 2011, the eruption of November 23, 2013 was chosen as a test-case. Results show some variations in the SNR data that can be correlated with the presence of an ash-laden plume in the atmosphere. Benefits and limitations of the method are highlighted

Precisely Co-located Cameras with High Geometric and Thermo-mechanical Stability

Hyper-realistic telepresence is achieved by mounting an array of carefully calibrated cameras on a monitor. High-quality, three-dimensional (3D) telepresence is predicated on highly stable camera positions, e.g., cameras calibrated to a fraction of a millimeter, which, during operation, stay in position to within a fraction of a millimeter. The typical, bezel-mounted camera array in a monitor experiences thermally induced post-calibration positional drift large enough to make hyper-realistic telepresence infeasible. This disclosure describes cameras that are mounted in a manner that leverages the thermal stability and isolation of the cover glass of the monitor to achieve extremely stable camera positioning that lasts through the entirety of a video recording or conferencing session, and into future sessions. Mounting cameras directly on the cover glass results in advantages other than thermo-mechanical stability, such as simplified design, modularized assembly, accurate eye-tracking resulting in a better 3D viewing experience, etc

Two-year stability and change of neuroticism and extraversion in treated and untreated persons with depression: findings from the Netherlands Study of Depression and Anxiety (NESDA)

AbstractBackgroundThe personality dimensions neuroticism and extraversion likely represent part of the vulnerability to depression. The stability over longer time periods of these personality dimensions in depressed patients treated with psychological treatment or medication and in untreated persons with depression in the general population remains unclear. Stability of neuroticism and extraversion in treated and untreated depressed persons would suggest that part of the vulnerability to depression remains stable over time. The current study addressed the question whether treatment in depressed patients is related to changes in neuroticism and extraversion.MethodsData are from 709 patients with major depressive disorder participating in a cohort study (Netherlands Study of Depression and Anxiety; NESDA). We determined the 2-year stability of extraversion and neuroticism in treated and untreated persons and related change in depression severity to change in personality over time.ResultsNeuroticism decreased from baseline to 2-year follow-up (d=0.73) in both treated and untreated persons. Extraversion did not change significantly after controlling for neuroticism and depression severity at baseline and follow-up. Decreased depressive symptoms over time were related to decreased neuroticism (d=1.91) whereas increased depressive symptoms over time were unrelated to neuroticism (d=0.06).LimitationsPatients were not randomized to treatment conditions and the groups are therefore not directly comparable.ConclusionsTreated patients with depression in the general population improve just as much on depression severity and neuroticism as untreated persons with depression. This suggests that changes in neuroticism in the context of treatment likely represent mood-state effects rather than direct effects of treatment

Long dephasing time and high temperature ballistic transport in an InGaAs open quantum dot

We report on measurements of the magnetoconductance of an open circular InGaAs quantum dot between 1.3K and 204K. We observe two types of magnetoconductance fluctuations: universal conductance fluctuations (UCFs), and 'focusing' fluctuations related to ballistic trajectories between openings. The electron phase coherence time extracted from UCFs amplitude is larger than in GaAs/AlGaAs quantum dots and follows a similar temperature dependence (between T^-1 and T^-2). Below 150K, the characteristic length associated with 'focusing' fluctuations shows a slightly different temperature dependence from that of the conductivity.Comment: 6 pages, 4 figures, proceedings of ICSNN2002, to appear in Physica

Saturation of dephasing time in mesoscopic devices produced by a ferromagnetic state

We consider an exchange model of itinerant electrons in a Heisenberg ferromagnet and we assume that the ferromagnet is in a fully polarized state. Using the Holstein-Primakoff transformation we are able to obtain a boson-fermion Hamiltonian that is well-known in the interaction between light and matter. This model describes the spontaneous emission in two-level atoms that is the proper decoherence mechanism when the number of modes of the radiation field is taken increasingly large, the vacuum acting as a reservoir. In the same way one can see that the interaction between the bosonic modes of spin waves and an itinerant electron produces decoherence by spin flipping with a rate proportional to the size of the system. In this way we are able to show that the experiments on quantum dots, described in D. K. Ferry et al. [Phys. Rev. Lett. {\bf 82}, 4687 (1999)], and nanowires, described in D. Natelson et al. [Phys. Rev. Lett. {\bf 86}, 1821 (2001)], can be understood as the interaction of itinerant electrons and an electron gas in a fully polarized state.Comment: 10 pages, no figure. Changed title. Revised version accepted for publication in Physical Review

Negative mood-induction modulates default mode network resting-state functional connectivity in chronic depression

BACKGROUND: The aim of this study was to investigate the effects of sad mood on default mode network (DMN) resting-state connectivity in persons with chronic major depressive disorder (cMDD). METHODS: Participants with a diagnosis of cMDD (n=18) and age, gender and education level matched participants without a diagnosis of depression (n=18) underwent a resting-state fMRI scan, before and after a sad mood induction. The posterior cingulate cortex (PCC) was used as a seed for DMN functional connectivity across the two resting-state measurements. RESULTS: Mood ratings decreased in both groups following the sad mood induction procedure. PCC connectivity with the parahippocampal gyrus, the superior temporal gyrus and the anterior inferior temporal cortex increased in cMDD patients following the sad mood induction, whereas it decreased in non-patient controls. PCC connectivity with the anterior prefrontal cortex and the precuneus decreased in cMDD patients following the sad mood induction, whereas it increased in non-patient controls. LIMITATIONS: Limitations of this study include the relatively small sample size and lack of a clinical control group. CONCLUSIONS: These findings are in line with neurobiological models of depression suggesting that the observed changes in DMN connectivity following the sad mood induction might reflect a failure to exert cognitive control over negative memory retrieval in patients with cMDD