1,513 research outputs found

    Control of interlayer exchange coupling in Fe/Cr/Fe trilayers by ion beam irradiation

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    The manipulation of the antiferromagnetic interlayer coupling in the epitaxial Fe/Cr/Fe(001) trilayer system by moderate 5 keV He ion beam irradiation has been investigated experimentally. It is shown that even for irradiation with very low fluences (10^14 ions/cm^2) a drastic change in strength of the coupling appears. For thin Cr-spacers (below 0.6 - 0.7 nm) the coupling strength decreases with fluence, becoming ferromagnetic for fluences above (2x10^14 ions/cm^2). The effect is connected with the creation of magnetic bridges in the layered system due to atomic exchange events caused by the bombardment. For thicker Cr spacers (0.8 - 1.2 nm) an enhancement of the antiferromagnetic coupling strength is found. A possible explanation of the enhancement effect is given.Comment: Submitted to PR

    Comparison of Two Low-Power Electronic Interfaces for Capacitive Mems Sensors

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    The paper discusses the importance and the issues of interfacing capacitive sensors. Two architectures applicable for interfacing capacitive sensors are presented. The first solution was designed to interface a capacitive humidity sensor designed and built for a humidity-dependent monolithic capacitor developed at Budapest University of Technology and Economics. The second case presents the possible read-out solutions for a SOI-MEMS accelerometer. Both of the architectures were built and tested in a discrete implementation to qualify the methods before the integrated realization. The paper presents a detailed comparison of the two methodsComment: Submitted on behalf of EDA Publishing Association (http://irevues.inist.fr/EDA-Publishing

    Map Showing the Distribution of Surficial Sediments in Fishers Island Sound, New York, Connecticut, and Rhode Island

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    The data presented on this map were collected as part of a State of Connecticut and U.S. Geological Survey (USGS) cooperative program intended to further understand the marine geology of Connecticut and Long Island Sound. The purpose of this cooperative program is (1) to resolve sedimentologic and oceanographic problems and data gaps in Long Island Sound, (2) to integrate these findings with terrestrial data and the Pleistocene histories of Long Island and Connecticut, and (3) to initiate investigations of offshore resources that are keyed to the better management of Long Island Sound. With this in mind, the fundamental objectives of this study were to determine the distribution of surficial sediments in Fishers Island Sound and to describe the active sedimentary processes

    Discrete structure of ultrathin dielectric films and their surface optical properties

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    The boundary problem of linear classical optics about the interaction of electromagnetic radiation with a thin dielectric film has been solved under explicit consideration of its discrete structure. The main attention has been paid to the investigation of the near-zone optical response of dielectrics. The laws of reflection and refraction for discrete structures in the case of a regular atomic distribution are studied and the structure of evanescent harmonics induced by an external plane wave near the surface is investigated in details. It is shown by means of analytical and numerical calculations that due to the existence of the evanescent harmonics the laws of reflection and refraction at the distances from the surface less than two interatomic distances are principally different from the Fresnel laws. From the practical point of view the results of this work might be useful for the near-field optical microscopy of ultrahigh resolution.Comment: 25 pages, 16 figures, LaTeX2.09, to be published in Phys.Rev.

    Solar Wind Electron Interaction with the Dayside Lunar Surface and Crustal Magnetic Fields: Evidence for Precursor Effects

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    Electron distributions measured by Lunar Prospector above the dayside lunar surface in the solar wind often have an energy dependent loss cone, inconsistent with adiabatic magnetic reflection. Energy dependent reflection suggests the presence of downward parallel electric fields below the spacecraft, possibly indicating the presence of a standing electrostatic structure. Many electron distributions contain apparent low energy (<100 eV) upwardgoing conics (58% of the time) and beams (12% of the time), primarily in regions with non-zero crustal magnetic fields, implying the presence of parallel electric fields and/or wave-particle interactions below the spacecraft. Some, but not all, of the observed energy dependence comes from the energy gained during reflection from a moving obstacle; correctly characterizing electron reflection requires the use of the proper reference frame. Nonadiabatic reflection may also play a role, but cannot fully explain observations. In cases with upward-going beams, we observe partial isotropization of incoming solar wind electrons, possibly indicating streaming and/or whistler instabilities. The Moon may therefore influence solar wind plasma well upstream from its surface. Magnetic anomaly interactions and/or non-monotonic near surface potentials provide the most likely candidates to produce the observed precursor effects, which may help ensure quasi-neutrality upstream from the Moon

    How might secondary dementia prevention programs work in practice: a pre-implementation study of the APPLE-Tree program.

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    BACKGROUND: Over 850,000 people in the UK currently have dementia, and that number is expected to grow rapidly. One approach that may help slow or prevent this growth is personalized dementia prevention. For most people, this will involve targeted lifestyle changes. These approaches have shown promise in trials, but as of yet, the evidence for how to scale them to a population level is lacking. In this pre-implementation study, we aimed to explore stakeholder perspectives on developing system-readiness for dementia prevention programs. We focused on the APPLE-Tree program, one of several low-intensity, lifestyle-based dementia prevention interventions currently in clinical trials. METHODS: We conducted semi-structured interviews with health and social care professionals without previous experience with the APPLE-Tree program, who had direct care or managerial experience in services for older adults with memory concerns, without a dementia diagnosis. We used the Consolidated Framework for Implementation Research to guide interviews and thematic analysis. RESULTS: We interviewed 26 stakeholders: commissioners and service managers (n = 15) and frontline workers (n = 11) from eight NHS and 11 third sector organizations throughout England. We identified three main themes: (1) favorable beliefs in the effectiveness of dementia prevention programs in enhancing cognition and wellbeing and their potential to fill a service gap for people with memory concerns, (2) challenges related to funding and capacity to deliver such programs at organizations without staff capacity or higher prioritization of dementia services, and (3) modifications to delivery and guidance required for compatibility with organizations and patients. CONCLUSION: This study highlights likely challenges in scale-up if we are to make personalized dementia prevention widely available. This will only be possible with increased funding of dementia prevention activities; integrated care systems, with their focus on prevention, may enable this. Scale-up of dementia prevention programs will also require clear outlines of their core and adaptable components to fit funding, patient, and facilitator needs

    Particle-In-Cell Simulations of the Solar Wind Interaction with Lunar Crustal Magnetic Anomalies: Magnetic Cusp Regions

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    As the solar wind is incident upon the lunar surface, it will occasionally encounter lunar crustal remanent magnetic fields. These magnetic fields are small-scale, highly non-dipolar, have strengths up to hundreds of nanotesla, and typically interact with the solar wind in a kinetic fashion. Simulations, theoretical analyses, and spacecraft observations have shown that crustal fields can reflect solar wind protons via a combination of magnetic and electrostatic reflection; however, analyses of surface properties have suggested that protons may still access the lunar surface in the cusp regions of crustal magnetic fields. In this first report from a planned series of studies, we use a 1 1/2-dimensional, electrostatic particle-in-cell code to model the self-consistent interaction between the solar wind, the cusp regions of lunar crustal remanent magnetic fields, and the lunar surface. We describe the self-consistent electrostatic environment within crustal cusp regions and discuss the implications of this work for the role that crustal fields may play regulating space weathering of the lunar surface via proton bombardment
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