Stroboscopic Laser Diagnostics for Detection of Ordering in One-Dimensional Ion beam

A novel diagnostic method for detecting ordering in one-dimensional ion beams is presented. The ions are excited by a pulsed laser at two different positions along the beam and fluorescence is observed by a group of four photomultipliers. Correlation in fluorescence signals is firm indication that the ion beam has an ordered structure.Comment: 7 pages, REVTEX, fig3 uuencoded, figs 1-2 available upon request from [email protected], to appear in Phys. Rev.

Anti-inflammatory response of IL-4, IL-10 and TGF-beta in patients with systemic inflammatory response syndrome.

The systemic inflammatory response syndrome (SIRS) is an inflammatory process seen in association with a large number of clinical infective and non-infective conditions. The aim of this study was to investigate the role of anti-inflammatory cytokines such as interleukin-4 (IL-4), interleukin-10 (IL-10), and transforming growth factor-beta (TGF-beta). Serum levels of IL-4, IL-10 and TGF-beta were determined in 45 patients with SIRS: 38 patients had SIRS of infectious origin, whereas seven patients had non-infectious SIRS. Twenty healthy subjects were used as controls. Serum levels of IL-4, IL-10 and TGF-beta were determined by an immunoenzyme assay. A significant increase of IL-4 was observed in these patients at the time of diagnosis and 5 days later. In contrast, serum levels of IL-10 were not increased at the time of diagnosis, but a slight decrease was noted after 5 days. Serum levels of TGF-beta were not increased at time of diagnosis, and a slight increase was observed after 5 days. Serum levels of IL-4 were significantly higher in patients with infectious SIRS at the time of diagnosis, whereas no significant difference between infectious and non-infectious SIRS was noted for serum levels of IL-10 and TGF-beta at the time of diagnosis and 5 days later. During SIRS, serum levels of IL-4 were significantly increased with a significant correlation between IL-4 and mortality, and only levels of IL-4 were significantly increased in the SIRS caused by infectious stimuli

Spontaneous cognitive processes and the behavioral validation of time-varying brain connectivity

In cognitive neuroscience, focus is commonly placed on associating brain function with changes in objectively measured external stimuli or with actively generated cognitive processes. In everyday life, however, many forms of cognitive processes are initiated spontaneously, without an individual’s active effort and without explicit manipulation of behavioral state. Recently, there has been increased emphasis, especially in functional neuroimaging research, on spontaneous correlated activity among spatially segregated brain regions (intrinsic functional connectivity) and, more specifically, on intraindividual fluctuations of such correlated activity on various time scales (time-varying functional connectivity). In this Perspective, we propose that certain subtypes of spontaneous cognitive processes are detectable in time-varying functional connectivity measurements. We define these subtypes of spontaneous cognitive processes and review evidence of their representations in time-varying functional connectivity from studies of attentional fluctuations, memory reactivation, and effects of baseline states on subsequent perception. Moreover, we describe how these studies are critical to validating the use of neuroimaging tools (e.g., fMRI) for assessing ongoing brain network dynamics. We conclude that continued investigation of the behavioral relevance of time-varying functional connectivity will be beneficial both in the development of comprehensive neural models of cognition, and in informing on best practices for studying brain network dynamics

The CERN laser-ion source

This paper describes the first results of a feasibility study undertaken at CERN to determine whether a laser-produced plasma can be used as a source of intense highly charged heavy ion beams. A variety of important measurements have been made, and the results are encouraging. Furthermore, a beam of highly charged light ions produced by the laser ion source has been accelerated successfully in a radio frequency quadrupole (RFQ) structur

Continuous Fuzzy Measurement of Energy for a Two-Level System

A continuous measurement of energy which is sharp (perfect) leads to the quantum Zeno effect (freezing of the state). Only if the quantum measurement is fuzzy, continuous monitoring gives a readout E(t) from which information about the dynamical development of the state vector of the system may be obtained in certain cases. This is studied in detail. Fuzziness is thereby introduced with the help of restricted path integrals equivalent to non-Hermitian Hamiltonians. For an otherwise undisturbed multilevel system it is shown that this measurement represents a model of decoherence. If it lasts long enough, the measurement readout discriminates between the energy levels and the von Neumann state reduction is obtained. For a two-level system under resonance influence (which undergoes in absence of measurement Rabi oscillations between the levels) different regimes of measurement are specified depending on its duration and fuzziness: 1) the Zeno regime where the measurement results in a freezing of the transitions between the levels and 2) the Rabi regime when the transitions maintain. It is shown that in the Rabi regime at the border to the Zeno regime a correlation exists between the time dependent measurement readout and the modified Rabi oscillations of the state of the measured system. Possible realizations of continuous fuzzy measurements of energy are sketched.Comment: 29 pages in LATEX, 1 figure in EPS, to be published in Physical Review

Quantum damping of position due to energy measurements

Quantum theory for measurements of energy is introduced and its consequences for the average position of monitored dynamical systems are analyzed. It turns out that energy measurements lead to a localization of the expectation values of other observables. This is manifested, in the case of position, as a damping of the motion without classical analogue. Quantum damping of position for an atom bouncing on a reflecting surface in presence of a homogeneous gravitational field is dealt in detail and the connection with an experiment already performed in the classical regime is studied. We show that quantum damping is testable provided that the same measurement strength obtained in the experimental verification of the quantum Zeno effect in atomic spectroscopy [W. M. Itano et al., Phys. Rev. A {\bf 41}, 2295 (1990)] is made available.Comment: 19 pages + 4 figures available upon request; Plain REVTeX; To be published in Phys. Rev.

Understanding perirhinal contributions to perception and memory: Evidence through the lens of selective perirhinal damage

© 2019 Elsevier Ltd Although a memory systems view of the medial temporal lobe (MTL) has been widely influential in understanding how memory processes are implemented, a large body of work across humans and animals has converged on the idea that the MTL can support various other decisions, beyond those involving memory. Specifically, recent work suggests that perception of and memory for visual representations may interact in order to support ongoing cognition. However, given considerations involving lesion profiles in neuropsychological investigations and the correlational nature of fMRI, the precise nature of representations supported by the MTL are not well understood in humans. In the present investigation, three patients with highly specific lesions to MTL were administered a task that taxed perceptual and mnemonic judgments with highly similar face stimuli. A striking double dissociation was observed such that I.R., a patient with a cyst localized to right posterior PRc, displayed a significant impairment in perceptual discriminations, whereas patient A.N., an individual with a lesion in right posterior parahippocampal cortex and the tail of the right hippocampus, and S.D., an individual with bilateral hippocampal damage, did not display impaired performance on the perceptual task. A.N. and S.D. did, however, show impairments in memory performance, whereas patient I.R. did not. These results causally implicate right PRc in successful perceptual oddity judgments, however they suggest that representations supported by PRc are not necessary for correct mnemonic judgments, even in situations of high featural overlap

Dynamics of Quantum Collapse in Energy Measurements

The influence of continuous measurements of energy with a finite accuracy is studied in various quantum systems through a restriction of the Feynman path-integrals around the measurement result. The method, which is equivalent to consider an effective Schr\"odinger equation with a non-Hermitian Hamiltonian, allows one to study the dynamics of the wavefunction collapse. A numerical algorithm for solving the effective Schr\"odinger equation is developed and checked in the case of a harmonic oscillator. The situations, of physical interest, of a two-level system and of a metastable quantum-well are then discussed. In the first case the Zeno inhibition observed in quantum optics experiments is recovered and extended to nonresonant transitions, in the second one we propose to observe inhibition of spontaneous decay in mesoscopic heterostructures. In all the considered examples the effect of the continuous measurement of energy is a freezing of the evolution of the system proportional to the accuracy of the measurement itself.Comment: 20 pages with figures, compressed and uuencoded ps fil

Rethinking cultural diversity in the UK film sector:practices in community filmmaking

© The Author(s) 2017. Academic, policy and industry debates have tended to focus on the mainstream film sector when discussing cultural diversity. One of the persistent challenges for the sector has been how to diversify cultural representation and participation. This article suggests that participatory modes of community filmmaking make an important contribution to cultural diversity. Drawing on an evidence base derived from qualitative research conducted in three English regions, the article shifts the spotlight away from the mainstream and onto the margins of the film sector in order to explore more ‘bottom-up’ approaches to cultural diversity. It examines how community filmmakers interpret and engage with questions of cultural diversity and how this connects to the participatory and business practices that they adopt. The findings highlight the significance of processes of practice in how mediated cultural diversity manifests itself and the value of community filmmaking in contributing to wider cultural diversity debates and practices.The authors thank the Arts and Humanities Research Council (UK) for funding the ‘Community Filmmaking and Cultural Diversity: Practice, Innovation and Policy project’ (2013–2014)