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  • 1
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    On‐site non‐destructive determination of the remanent magnetization of archaeological finds using field magnetometers (2022)
    In:  Archaeological Prospection
    Details
    Publication Date: 2022-06-13
    Description: The determination of the natural remanent magnetization (NRM) of archaeological features can be used for magnetic modelling, joining of shards, archaeomagnetic dating or the investigation of the firing–cooling–collapsing order of ancient buildings. The measurement of NRM is normally conducted on cylindrical or cubic samples in the laboratory. Nevertheless, archaeological finds should preferably not be destroyed, and laboratory instruments are high in costs. Therefore, we propose a lightweight and portable measurement set-up including already available field magnetometers (preferably caesium magnetometers) in which the archaeological sample of arbitrary shape, in our case a piece of daub, is mounted inside a gimbal to be rotated in all directions. The magnetic field of the sample is measured at a large number of rotational positions with the magnetometer kept at fixed position. In these measurements, the unknown direction of the NRM vector of the sample is rotated, whereas the average magnetic susceptibility of the sample and the ambient magnetic field are constant and known. Hence, the vector of NRM can be determined through least-squares inversion. For the inversion computation, the sample volume is discretized either as voxel model or approximated as an equivalent sphere. Under certain conditions depending on sample–sensor distance, dipole moment and radius of the sample, the approximation by a sphere is valid without effect on the accuracy of results. Empirically determined functions quantifying these conditions for different sensor sensitivities and noise levels are provided. Validation with laboratory measurements on palaeomagnetic subsamples from the destroyed daub samples indicate that the NRM can be determined by our proposed method with a maximum error in inclination of 2°, in declination of 20° and in magnetization of ±0.6 A/m. This is accurate enough, for example, to determine from daub pieces of burnt house remains whether the building was burnt and cooled before or after it collapsed.
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 2
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    MISR observations of Etna volcanic plumes (2013)
    Details
    Publication Date: 2017-04-04
    Description: In the last twelve years, Mt. Etna, located in eastern Sicily, has produced a great number of explosive eruptions. Volcanic plumes have risen to several km above sea level and created problems for aviation and the communities living near the volcano. A reduction of hazards may be accomplished using remote sensing techniques to evaluate important features of volcanic plumes. Since 2000, the Multiangle Imaging SpectroRadiometer (MISR) on board NASA’s Terra spacecraft has been extensively used to study aerosol dispersal and to extract the three-dimensional structure of plumes coming from anthropogenic or natural sources, including volcanoes. In the present work, MISR data from several explosive events occurring at Etna are analyzed using a program named MINX (MISR INteractive eXplorer). MINX uses stereo matching techniques to evaluate the height of the volcanic aerosol with a precision of a few hundred meters, and extracts aerosol properties from the MISR Standard products. We analyzed twenty volcanic plumes produced during the 2000, 2001, 2002–03, 2006 and 2008 Etna eruptions, finding that volcanic aerosol dispersal and column height obtained by this analysis is in good agreement with ground-based observations. MISR aerosol type retrievals: (1) clearly distinguish volcanic plumes that are sulphate and/or water vapor dominated from ash-dominated ones; (2) detect even low concentrations of volcanic ash in the atmosphere; (3) demonstrate that sulphate and/or water vapor dominated plumes consist of smaller-sized particles compared to ash plumes. This work highlights the potential of MISR to detect important volcanic plume characteristics that can be used to constrain the eruption source parameters in volcanic ash dispersion models. Further, the possibility of discriminating sulphate and/or water vapor dominated plumes from ash-dominated ones is important to better understand the atmospheric impact of these plumes
    Description: Published
    Description: D06210
    Description: 1.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic ash plume ; MISR ; 01. Atmosphere::01.01. Atmosphere::01.01.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
    Electronic Resource
    Electronic Resource
    An X–Y encoder with fast centroid calculation for large multiwire proportional chambers : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 655-658 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The system described here is part of a data acquisition system for macromolecular crystallography using a two-dimensional wire chamber with a spherical drift space. The readout consists of 2×128 cathode strips (4 mm width) which are connected to shaping amplifiers coupled to a fast high precision position encoder. Cathode amplitudes are converted digitally with flash analog-to-digital converters and valid cathode clusters give between 3 to 5 digital amplitudes. A specialized VME module calculates the center of gravity of the cluster. The entire system is constructed as a VME structure and is under program control from a VALET-plus VME microcomputer system (developed at the CERN) which allows fine tuning of the electronic system. Data acquisition rate is presently 200 kHz with less than 20% data loss. The useful sensitive area of the detector is a disk (diameter 486 mm). Local positional resolution is around 150 μm root-mean-square and long range positional reproducibility is better than 200 μm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1142681
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of an electric field on a methane molecule. II. Calculation of the degeneracy splitting of the ν3 band. Expression of the second derivatives of the CH4 dipole moment and evaluation of the second derivative of the C–H bond polarizability (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 2653-2660 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In order to interpret infrared spectra of methane adsorbed in NaA at low temperature, we have calculated the frequencies of CH4 and CD4 perturbed by an electric field. This calculation needs the expressions of the second derivative of the dipole moment and the polarizability. These later were given by Montero and we have expressed the terms ∂2m/∂Si∂Sj using the same approximations: additivity of the CH bond dipole derivatives. We find for the CH bond derivatives: μ'=−0.7×10−10 esu, μ‘=+1.5×10−2 esu. The magnitude of the field (3×105 esu) has been determined by the intensity of the induced ν1 band. The orientation of the field deduced from the experiments, is along a C3 axis of the molecule. Adjusting theoretical and experimental results, we have calculated the parallel and perpendicular second derivatives of the CH bond polarizability 2β‘+δ‘=−6.4×10−8 cm, δ‘− β‘=+5.3×10−8 cm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449267
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of an electric field on a methane molecule. I. Infrared analysis of methane (CH4–CD4) adsorbed in NaA zeolite in the temperature range 150–20 K (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 2646-2652 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The spectra of methane adsorbed at low temperature in NaA zeolite show two strong effects of the field existing in the cavities: (i) the appearance of the ν1 forbidden band which increases when decreasing the temperature and (ii) the splitting of the ν3 degenerate band. The variation with T of its components lead to the conclusion that the molecule progressively is oriented in a C3V configuration with respect to the field.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449266
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  • 6
    Electronic Resource
    Electronic Resource
    Diffusivity of the hydrogen molecule sorbed in NaA zeolite by a neutron scattering experiment (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5097-5102 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The diffusion of hydrogen in NaA zeolite was studied by incoherent neutron scattering. An experiment was carried out on samples loaded with 1.2 to 3.4 molecules per cavity and at several temperatures from 70 to 150 K. The angular (θ) dependence of the elastic and quasielastic intensities shows that the H2 molecule has a translational motion in a nonrestricted volume. A diffusion model where the molecule undergoes isotropic jumps of mean length l¯=3.9 A(ring) independent of temperature and is at rest for a time τ0 between two jumps accounts for the width of the quasielastic scattering in the entire (θ,T) range (τ0=10.8 ps at T=100 K). This leads to a diffusion coefficient D(cm2/s)=6×10−4 exp(E/RT) with E=2 kJ/mol for the less loaded samples. The diffusion coefficient increases slightly with the loading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457601
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  • 7
    Electronic Resource
    Electronic Resource
    Molecular dynamics by numerical simulation in zeolites: Methane in NaA (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 7482-7491 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A molecular dynamical study of one methane molecule in a cavity of NaA zeolite is performed in order to compare calculated to experimental data obtained by infrared spectroscopy and neutron scattering experiments in the temperature range 300–30 K. The calculation shows the trajectory of the molecule in the cavity and then the occupied volume as a function of energy. It allows the calculation of average quantities and correlation functions: (i) the mean field felt by the molecule comparable to the field responsible for the induced infrared band ν1, (ii) the average of the potential energy (to be compared to the heat of adsorption) and of the velocity squared, (iii) the external frequency distribution, and (iv) the position autocorrelation function which is related to the dynamical structure factor seen by neutron scattering.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456182
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  • 8
    Electronic Resource
    Electronic Resource
    The spherical drift chamber used at LURE for protein crystallography; last developments, performances, and results (invited) (abstract) : INTERNATIONAL CONFERENCE ON SYNCHROTRON RADIATION INSTRUMENTATION (1989)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 60 (1989), S. 1568-1568 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We have developed at LURE a multiwire proportional chamber with a spherical drift space. The wire chamber consists of two cathode planes, comprising 512 wires with a spacing of 1 mm, set on both sides of the anodic plane. The drift space, a gas filled region bounded by two spherically curved electrodes 144 mm apart, offers several advantages: high quantum efficiency, no parallax effect, equivalent spatial resolution in both directions, and smoothing of the pulsed structure of the synchrotron radiation. The gaseous mixture of argon-xenon (58%), ethane (40%), and ethyl alcohol (2%) is circulated in a closed circuit and is continuously purified. Ethyl alcohol, which avoids electrical discharges and sparks, is essential to operate the instrument at high counting rates (〉300 000 events/s). The signal processing, which makes use of one amplifier per cathode wire and of fast priority encoders, determines both coordinates with a resolution of 1 mm and a dead time of 240 ns. Each encoded event is stored into a 512×512 16 bit CAMAC histogramming memory. The experiment is controlled by a PDP11/34 linked to a VAX by a direct memory access channel. A complete set of programs, which performs the data collection and an off line data reduction, is operational. The adaptation of madnes, a general software package which performs an on line data reduction, is under way. Data, collected on a lysozyme crystal to 3.4-A(ring) resolution, give a reliability factor based on intensities of equivalent reflections of 4.7% without absorption corrections; the variation of the detector efficiency is 〈2.7%. A new version of the instrument is under realization. The position encoder, which uses flash ADCs and signal processors, has a resolution of 0.5 mm. Data are stored into a 1024×1024 16 bit VME histogramming memory linked to a micro VAX.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141036
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  • 9
    Electronic Resource
    Electronic Resource
    AN ENVIRONMENTAL APPROACH TO MENTAL HEALTH (1963)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 107 (1963), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1963.tb13304.x
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  • 10
    Electronic Resource
    Electronic Resource
    Diffraction and diffuse scattering measurements in material science: Improvement brought to a six-circle goniometer on a synchrotron beam line : Proceedings of the 4th international conference on synchrotron radiation instructumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 988-991 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The six-circle diffractometer D23 set up in LURE-DCI (bending magnet) at Orsay has been improved since its first presentation in 1987 [M. Bessiere, G. Bessenay, J. Frouin, M. Jouvin, and S. Lefebvre, Nucl. Instrum. Methods A 261, 591 (1987)]. We present a new design for the sagittal focusing monochromator, a two-mirror device for harmonics rejection and detectors for adjustments. All these modifications are now operational and can be used together with a crystal analyzer for powder studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143717
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