1,956 research outputs found
Recent progress in tidal modeling
Recent contributions to tidal theory during the last five years are reviewed. Specific areas where recent progress has occurred include: the action of mean wind and dissipation on tides, interactions of other waves with tides, the use of TGCM in tidal studies. Furthermore, attention is put on the nonlinear interaction between semidiurnal and diurnal tides. Finally, more realistic thermal excitation and background wind and temperature models have been developed in the past few years. This has led to new month-to-month numerical simulations of the semidiurnal tide. Some results using these models are presented and compared with ATMAP tidal climatologies
The fourier transform for certain HyperKähler fourfolds
Using a codimension- algebraic cycle obtained from the Poincar\'e line
bundle, Beauville defined the Fourier transform on the Chow groups of an
abelian variety and showed that the Fourier transform induces a
decomposition of the Chow ring . By using a codimension- algebraic
cycle representing the Beauville--Bogomolov class, we give evidence for the
existence of a similar decomposition for the Chow ring of hyperK\"ahler
varieties deformation equivalent to the Hilbert scheme of length- subschemes
on a K3 surface. We indeed establish the existence of such a decomposition for
the Hilbert scheme of length- subschemes on a K3 surface and for the variety
of lines on a very general cubic fourfold.The first author is supported by the Simons Foundation as a Simons Postdoctoral Fellow. The second author is supported by EPSRC Early Career Fellowship number EP/K005545/1.This is the author accepted manuscript. The final version is available from the American Mathematical Sociery via http://dx.doi.org/10.1090/memo/113
IRIS Observations of Spicules and Structures Near the Solar Limb
We have analyzed IRIS spectral and slit-jaw observations of a quiet region
near the South Pole. In this article we present an overview of the
observations, the corrections, and the absolute calibration of the intensity.
We focus on the average profiles of strong (Mg ii h and k, C ii and Si iv), as
well as of weak spectral lines in the near ultraviolet (NUV) and the far
ultraviolet (FUV), including the Mg ii triplet, thus probing the solar
atmosphere from the low chromosphere to the transition region. We give the
radial variation of bulk spectral parameters as well as line ratios and
turbulent velocities. We present measurements of the formation height in lines
and in the NUV continuum, from which we find a linear relationship between the
position of the limb and the intensity scale height. We also find that low
forming lines, such as the Mg ii triplet, show no temporal variations above the
limb associated with spicules, suggesting that such lines are formed in a
homogeneous atmospheric layer and, possibly, that spicules are formed above the
height of 2 arc sec. We discuss the spatio-temporal structure near the limb
from images of intensity as a function of position and time. In these images,
we identify p-mode oscillations in the cores of lines formed at low heights
above the photosphere, slow moving bright features in O i and fast moving
bright features in C ii. Finally, we compare the Mg ii k and h line profiles,
together with intensity values of the Balmer lines from the literature, with
computations from the PROM57Mg non-LTE model developed at the Institut
d'Astrophysique Spatiale and estimated values of the physical parameters. We
obtain electron temperatures in the range of K at small heights to
K at large heights, electron densities from to
cm and a turbulent velocity of km/s.Comment: Accepted for publication in Solar Physic
Optical determination and identification of organic shells around nanoparticles: application to silver nanoparticles
We present a simple method to prove the presence of an organic shell around
silver nanoparticles. This method is based on the comparison between optical
extinction measurements of isolated nanoparticles and Mie calculations
predicting the expected wavelength of the Localized Surface Plasmon Resonance
of the nanoparticles with and without the presence of an organic layer. This
method was applied to silver nanoparticles which seemed to be well protected
from oxidation. Further experimental characterization via Surface Enhanced
Raman Spectroscopy (SERS) measurements allowed to identify this protective
shell as ethylene glycol. Combining LSPR and SERS measurements could thus give
proof of both presence and identification for other plasmonic nanoparticles
surrounded by organic shells
Cost-efficient digital twins for design space exploration: A modular platform approach
The industrial need to predict the behaviour of radically new products brings renewed interest in how to set up and make use of physical prototypes and testing. However, conducting physical testing of a large number of radical concepts is still a costly approach. This paper proposes an approach to actively use digital twins in the early phases where the design can be largely changed. The approach is based on creating a set of digital twin modules that can be reused and recomposed to create digital twin variants. However, this paper considers that developing a digital twin can be very costly. Therefore, the approach focuses on supporting the decisions about the optimal mix of modules, and about whether a new digital twin module should be developed. The approach is applied to an industrial case derived from the collaboration with two space manufacturers. The results highlight how the design of the modular platform has an impact on the cost of the digital twin, if commonality and reusability aspects are considered. These results point at the cost-efficiency of applying a modular approach to digital twin creation, as a means to reuse the results from physical testing to validate new designs and their ranges of validit
Ionization states of metallic elements in a quiescent prominence
Inthe frame of the Joint Observing Program 133, which was run during the 6th MEDOC Campaign, a quiet prominence was observed on the 1st of November 2000, between17:30-20:00 UT. From the data we obtained, we want to characterize the emission line profiles and to study the different ionization states of many chemical elements present in the cool plasma of the observed prominence. We also intend to analyze the macroscopic velocities of the material and compare the results with theoretical calculations
Recent advances using gold nanoparticles as a promising multimodal tool for tissue engineering and regenerative medicine
Uncorrected proofGold nanoparticles (AuNPs) have arisen a lot of interest in the clinical realms of nanomedicine. Despite the large ad- vances made in cancer research using AuNPs, their use in tissue engineering and regenerative medicine (TERM) is still in its infancy. Herein, it is discussed the properties, functionalization, and emerging use of AuNPs as a multifunctional and multimodal platform for drug delivery, phototherapy, diagnostic and cell imaging purposes. Moreover, the recent reports related to the ability of AuNPs to enhance stem cell differentiation for bone tissue engineering, to enhance the mechanical and adhesive properties of scaffolds and surface topography to guide cell behaviors are addressed.The authors would like to thank QREN (ON.2 –
NORTE-01-0124-FEDER-000018) co-financed by North Portugal
Regional Operational Program (ON.2 – O Novo Norte), under the National
Strategic Reference Framework (NSRF), through the European
Regional Development Fund (ERDF) for providing financial support
to this project. The Portuguese Foundation for Science and Technology
(FCT) distinction attributed to J.M. Oliveira under the FCT
Investigator program (IF/00423/2012) is also greatly acknowledged.
The authors also thank the financial support provided under the ERC
funded project ComplexiTE (Grant
ERC-2012-ADG_20120216-321266)
First High-resolution Spectroscopic Observations of an Erupting Prominence Within a Coronal Mass Ejection by the Interface Region Imaging Spectrograph (IRIS)
Spectroscopic observations of prominence eruptions associated with coronal
mass ejections (CMEs), although relatively rare, can provide valuable plasma
and 3D geometry diagnostics. We report the first observations by the Interface
Region Imaging Spectrograph (IRIS) mission of a spectacular fast CME/prominence
eruption associated with an equivalent X1.6 flare on 2014 May 9. The maximum
plane-of-sky and Doppler velocities of the eruption are 1200 and 460 km/s,
respectively. There are two eruption components separated by ~200 km/s in
Doppler velocity: a primary, bright component and a secondary, faint component,
suggesting a hollow, rather than solid, cone-shaped distribution of material.
The eruption involves a left-handed helical structure undergoing
counter-clockwise (viewed top-down) unwinding motion. There is a temporal
evolution from upward eruption to downward fallback with less-than-free-fall
speeds and decreasing nonthermal line widths. We find a wide range of Mg II k/h
line intensity ratios (less than ~2 expected for optically-thin thermal
emission): the lowest ever-reported median value of 1.17 found in the fallback
material and a comparably high value of 1.63 in nearby coronal rain and
intermediate values of 1.53 and 1.41 in the two eruption components. The
fallback material exhibits a strong () linear correlation between
the k/h ratio and the Doppler velocity as well as the line intensity. We
demonstrate that Doppler dimming of scattered chromospheric emission by the
erupted material can potentially explain such characteristics.Comment: 12 pages, 6 figures, accepted by ApJ (Feb 15, 2015
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