1,075 research outputs found
Certificateless Public Auditing Protocol with Constant
To provide the integrity of outsourced data in the cloud storage services, many public auditing schemes which allow a user to check the integrity of the outsourced data have been proposed. Since most of the schemes are constructed on Public Key Infrastructure (PKI), they suffer from several concerns like management of certificates. To resolve the problems, certificateless public auditing schemes also have been studied in recent years. In this paper, we propose a certificateless public auditing scheme which has the constant-time verification algorithm. Therefore, our scheme is more efficient than previous certificateless public auditing schemes. To prove the security of our certificateless public auditing scheme, we first define three formal security models and prove the security of our scheme under the three security models
Growth and atomically resolved polarization mapping of ferroelectric thin film
Aurivillius ferroelectric (BWO) encompasses a broad range of
functionalities, including robust fatigue-free ferroelectricity, high
photocatalytic activity, and ionic conductivity. Despite these promising
characteristics, an in-depth study on the growth of BWO thin films and
ferroelectric characterization, especially at the atomic scale, is still
lacking. Here, we report pulsed laser deposition (PLD) of BWO thin films on
(001) substrates and characterization of ferroelectricity using the
scanning transmission electron microscopy (STEM) and piezoresponse force
microscopy (PFM) techniques. We show that the background oxygen gas pressure
used during PLD growth mainly determines the phase stability of BWO films,
whereas the influence of growth temperature is comparatively minor. Atomically
resolved STEM study of a fully strained BWO film revealed collective in-plane
polar off-centering displacement of W atoms. We estimated the spontaneous
polarization value based on polar displacement mapping to be about 54 4
, which is in good agreement with the bulk polarization value.
Furthermore, we found that pristine film is composed of type-I and type-II
domains, with mutually orthogonal polar axes. Complementary PFM measurements
further elucidated that the coexisting type-I and type-II domains formed a
multidomain state that consisted of 90 domain walls (DWs) alongside
multiple head-to-head and tail-to-tail 180 DWs. Application of an
electrical bias led to in-plane 180 polarization switching and 90
polarization rotation, highlighting a unique aspect of domain switching, which
is immune to substrate-induced strain.Comment: This document is the Accepted Manuscript version of a Published Work
that appeared in final form in ACS Applied Electronic Materials, \copyright
American Chemical Society after peer review and technical editing by the
publisher. To access the final edited and published work see:
https://pubs.acs.org/doi/full/10.1021/acsaelm.1c00005 .This submission
contains 34 page
Geopotential Field Anomaly Continuation with Multi-Altitude Observations
Conventional gravity and magnetic anomaly continuation invokes the standard Poisson boundary condition of a zero anomaly at an infinite vertical distance from the observation surface. This simple continuation is limited, however, where multiple altitude slices of the anomaly field have been observed. Increasingly, areas are becoming available constrained by multiple boundary conditions from surface, airborne, and satellite surveys. This paper describes the implementation of continuation with multi-altitude boundary conditions in Cartesian and spherical coordinates and investigates the advantages and limitations of these applications. Continuations by EPS (Equivalent Point Source) inversion and the FT (Fourier Transform), as well as by SCHA (Spherical Cap Harmonic Analysis) are considered. These methods were selected because they are especially well suited for analyzing multi-altitude data over finite patches of the earth such as covered by the ADMAP database. In general, continuations constrained by multi-altitude data surfaces are invariably superior to those constrained by a single altitude data surface due to anomaly measurement errors and the non-uniqueness of continuation
Oxygen Partial Pressure during Pulsed Laser Deposition: Deterministic Role on Thermodynamic Stability of Atomic Termination Sequence at SrRuO3/BaTiO3 Interface
With recent trends on miniaturizing oxide-based devices, the need for
atomic-scale control of surface/interface structures by pulsed laser deposition
(PLD) has increased. In particular, realizing uniform atomic termination at the
surface/interface is highly desirable. However, a lack of understanding on the
surface formation mechanism in PLD has limited a deliberate control of
surface/interface atomic stacking sequences. Here, taking the prototypical
SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) heterostructure as a model system, we
investigated the formation of different interfacial termination sequences
(BaO-RuO2 or TiO2-SrO) with oxygen partial pressure (PO2) during PLD. We found
that a uniform SrO-TiO2 termination sequence at the SRO/BTO interface can be
achieved by lowering the PO2 to 5 mTorr, regardless of the total background gas
pressure (Ptotal), growth mode, or growth rate. Our results indicate that the
thermodynamic stability of the BTO surface at the low-energy kinetics stage of
PLD can play an important role in surface/interface termination formation. This
work paves the way for realizing termination engineering in functional oxide
heterostructures.Comment: 27 pages, 6 figures, Supporting Informatio
A tracheoinnominate artery fistula presenting with massive hemorrhage in a 13-year-old boy
Despite its rarity, a tracheoinnominate artery fistula can result in catastrophic hemorrhage. Here, we describe a case of a 13-year-old boy with such a condition following tracheostomy. After identification of pulsatile bleeding from the tracheostoma, temporary control of hemorrhage was obtained using hyperinflation of the tracheostomy tube cuff. Subsequently, a lesion indicative of a tracheoinnominate artery fistula was found on a computed tomography scan, and the diagnosis was confirmed at surgery. After surgery, he was discharged with no recurrent bleeding. This case highlights the importance of high suspicion and prompt management of tracheoinnominate artery fistula
First-time comparison between NO2 vertical columns from GEMS and Pandora measurements
The Geostationary Environmental Monitoring Spectrometer (GEMS) is a UV–visible spectrometer onboard the GEO-KOMPSAT-2B satellite launched into geostationary orbit in February 2020. To evaluate GEMS NO2 column data, comparison was carried out using NO2 vertical column density (VCD) measured using direct-sunlight observations by the Pandora spectrometer system at four sites in Seosan, South Korea, during November 2020 to January 2021. Correlation coefficients between GEMS and Pandora NO2 data at four sites ranged from 0.35 to 0.48, with root mean square errors (RMSEs) from 4.7 × 1015 molec. cm-2 to 5.5 × 1015 molec. cm-2 for cloud fraction (CF) < 0.7. Higher correlation coefficients of 0.62–0.78 with lower RMSEs from 3.3 × 1015 molec. cm-2 to 4.3 × 1015 molec. cm-2 were found with CF < 0.3, indicating the higher sensitivity of GEMS to atmospheric NO2 in less-cloudy conditions. Overall, GEMS NO2 column data tend to be lower than those of Pandora due to differences in representative spatial coverage, with a large negative bias under high-CF conditions. With correction for horizontal representativeness in Pandora measurement coverage, the correlation coefficients range from 0.69 to 0.81 with RMSEs from 3.2 × 1015 molec. cm-2 to 4.9 × 1015 molec. cm-2 were achieved for CF < 0.3, showing the better correlation with the correction than that without the correction.</p
First-time comparison between NO2 vertical columns from Geostationary Environmental Monitoring Spectrometer (GEMS) and Pandora measurements
The Geostationary Environmental Monitoring Spectrometer (GEMS) is a UV-visible (UV-Vis) spectrometer on board the GEO-KOMPSAT-2B (Geostationary Korea Multi-Purpose Satellite 2B) satellite launched into a geostationary orbit in February 2020. To evaluate the GEMS NO2 total column data, a comparison was carried out using the NO2 vertical column density (VCD) that measured direct sunlight using the Pandora spectrometer system at four sites in Seosan, South Korea, from November 2020 to January 2021. Correlation coefficients between GEMS and Pandora NO2 data at four sites ranged from 0.35 to 0.48, with root mean square errors (RMSEs) from 4.7×1015 to 5.5×1015 molec. cm−2 for a cloud fraction (CF) <0.7. Higher correlation coefficients of 0.62–0.78 with lower RMSEs from 3.3×1015 to 5.0×1015 molec. cm−2 were found with CF <0.3, indicating the higher sensitivity of GEMS to atmospheric NO2 in less cloudy conditions. Overall, the GEMS NO2 total column data tended to be lower than the Pandora data, owing to differences in the representative spatial coverage, with a large negative bias under high CF conditions. With a correction for horizontal representativeness in the Pandora measurement coverage, correlation coefficients ranging from 0.69 to 0.81, with RMSEs from 3.2×1015 to 4.9×1015 molec. cm−2, were achieved for CF <0.3, showing a better correlation with the correction than without the correction.</p
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