666 research outputs found
A Verilog HDL digital architecture for delay calculation
A method for the calculation of the delay between two digital signals with central frequencies in the range [20, 300] Hz is presented. The method performs a delay calculation in order to determine the bearing angle of a sound source. Computing accuracy is tested against a previous implementation of the Cross Correlation Derivative method. A Verilog RTL model of the method has been tested on a Xilinx® FPGA in order to evaluate the real performance of the method. Simulations of an ASIC design on a standard CMOS technology predict a power saving of about 25 times per delay stage over previous implementations.Fil: Chacón-Rodríguez, A.. Universidad de Mar del Plata. Laboratorio de Componentes Electrónicos; ArgentinaFil: Martín-Pirchio, F. N.. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; ArgentinaFil: Julian, Pedro Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages". Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras. Instituto de Investigaciones en Ingeniería Eléctrica "Alfredo Desages"; ArgentinaFil: Mandolesi, Pablo Sergio. Universidad Nacional del Sur. Departamento de Ingeniería Eléctrica y de Computadoras; Argentin
Numerical Validation of the Incremental Launching Method of a Steel Bridge Through a Small-Scale Experimental Study
Double-electron ionization driven by inhomogeneous fields
Authors may self-archive the author’s accepted manuscript of their articles on their own websites. Authors may also deposit this version of the article in any repository, provided it is only made publicly available 12 months after official publication or later. He/ she may not use the publisher's version (the final article), which is posted on SpringerLink and other Springer websites, for the purpose of self-archiving or deposit. Furthermore, the author may only post his/her version provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be provided by inserting the DOI number of the article in the following sentence: “The final publication is available at Springer via https://link.springer.com/article/10.1007/s00340-017-6672-4"Electron–electron correlation effects play a crucial role in our understanding of sequential (SDI) and non-sequential double ionization (NSDI) mechanisms. Here, we present a theoretical study of NSDI driven by plasmonic-enhanced spatial inhomogeneous fields. By numerically solving the time-dependent Schrödinger equation for a linear reduced model of He and a double-electron time-evolution probability analysis, we provide evidence for enhancement effects in NSDI showing that the double ionization yield at lower laser peak intensities is increased due to the spatial inhomogeneous character of plasmonic-enhanced field. The change in the emission direction of the double-ion as a function of the field inhomogeneity degree demonstrates that plasmonic-enhanced fields could configure a reliable instrument to control the ion emission. Furthermore, our quantum mechanical model, as well as classical trajectory Monte Carlo simulations, show that inhomogeneous fields are as well as a useful tool for splitting the binary and recoil processes in the rescattering scenario.This work was supported by the project ELI-Extreme Light Infrastructure-phase 2 (Project No. CZ.02.1.01/0.0/0.0/
15_008/0000162) from European Regional Development Fund, Spanish MINECO (National Plan grants FIS2011-30465-C02-01, FOQUS No. FIS2013-46768-P, FISICATEAMO FIS2016-79508-P and Severo Ochoa Excellence Grant No. SEV-2015-0522), the Generalitat de Catalunya (SGR 874 and CERCA/Program) and Fundació Privada
Cellex Barcelona. N.S. was supported by the Erasmus Mundus Doctorate Program Europhotonics (Grant No. 159224-1-2009-1-FR-ERA MUNDUS-EMJD). N.S., A.C., and M.L. acknowledge ERC AdG OSYRIS, EU FETPRO QUIC and National Science Centre, Poland—Symfonia Grant 2016/20/W/ST4/00314. A. S. L. acknowledges Max Planck Center for Attosecond Science (MPC-AS). J. A. P.-H. acknowledges to the Spanish Ministerio de Economía y Competitivi-
dad (FURIAM Project No. FIS2013-47741-R and PALMA project FIS2016- 81056-R) and Laserlab-Europe (EU-H2020 654148). L.O.
acknowledges valuable input from Andre Staudte. The authors thankfully acknowledge the computer resources at MareNostrum, technical expertise and assistance provided by the Barcelona Supercomputing
Center and the Red Española de Supercomputación (RES)Peer ReviewedPostprint (author's final draft
Current sheet bifurcation and collapse in electron magnetohydrodynamics
Inertial effects in nonlinear magnetic reconnection are studied within the
context of 2D electron magnetohydrodynamics (EMHD) with resistive and viscous
dissipation. Families of nonlinear solutions for relevant current sheet
parameters are predicted and confirmed numerically in all regimes of interest.
Electron inertia becomes important for current sheet thicknesses below
the inertial length . In this case, in the absence of electron
viscosity, the sheet thickness experiences a nonlinear collapse. Viscosity
regularizes solutions at small scales. Transition from resistive to viscous
regimes shows a nontrivial dependence on resistivity and viscosity, featuring a
hysteresis bifurcation. In all accessible regimes, the nonlinear reconnection
rate is found to be explicitly independent of the electron inertia and
dissipation coefficients.Comment: submitted to publicatio
Wannier-Bloch approach to localization in high harmonics generation in solids
Emission of high-order harmonics from solids provides a new avenue in
attosecond science. On one hand, it allows to investigate fundamental processes
of the non-linear response of electrons driven by a strong laser pulse in a
periodic crystal lattice. On the other hand, it opens new paths toward
efficient attosecond pulse generation, novel imaging of electronic wave
functions, and enhancement of high-order harmonic generation (HHG) intensity. A
key feature of HHG in a solid (as compared to the well-understood phenomena of
HHG in an atomic gas) is the delocalization of the process, whereby an electron
ionized from one site in the periodic lattice may recombine with any other.
Here, we develop an analytic model, based on the localized Wannier wave
functions in the valence band and delocalized Bloch functions in the conduction
band. This Wannier-Bloch approach assesses the contributions of individual
lattice sites to the HHG process, and hence addresses precisely the question of
localization of harmonic emission in solids. We apply this model to investigate
HHG in a ZnO crystal for two different orientations, corresponding to wider and
narrower valence and conduction bands, respectively. Interestingly, for
narrower bands, the HHG process shows significant localization, similar to
harmonic generation in atoms. For all cases, the delocalized contributions to
HHG emission are highest near the band-gap energy. Our results pave the way to
controlling localized contributions to HHG in a solid crystal, with hard to
overestimate implications for the emerging area of atto-nanoscience
SUCCOR Nodes: May Sentinel Node Biopsy Determine the Need for Adjuvant Treatment?
Background
The SUCCOR cohort was developed to analyse the overall and disease-free survival at 5 years in women with FIGO 2009 stage IB1 cervical cancer. The aim of this study was to compare the use of adjuvant therapy in these women, depending on the method used to diagnose lymphatic node metastasis.
Patients and Methods
We used data from the SUCCOR cohort, which collected information from 1049 women with FIGO 2009 stage IB1 cervical cancer who were operated on between January 2013 and December 2014 in Europe. We calculated the adjusted proportion of women who received adjuvant therapy depending on the lymph node diagnosis method and compared disease free and overall survival using Cox proportional-hazards regression models. Inverse probability weighting was used to adjust for baseline potential confounders.
Results
The adjusted proportion of women who received adjuvant therapy was 33.8% in the sentinel node biopsy + lymphadenectomy (SNB+LA) group and 44.7% in the LA group (p = 0.02), although the proportion of positive nodal status was similar (p = 0.30). That difference was greater in women with negative nodal status and positive Sedlis criteria (difference 31.2%, p = 0.01). Here, those who underwent a SNB+LA had an increased risk of relapse [hazard ratio (HR) 2.49, 95% confidence interval (CI) 0.98–6.33, p = 0.056] and risk of death (HR 3.49, 95% CI 1.04–11.7, p = 0.042) compared with those who underwent LA.
Conclusions
Women in this study were less likely to receive adjuvant therapy if their nodal invasion was determined using SNB+LA compared with LA. These results suggest a lack of therapeutic measures available when a negative result is obtained by SNB+LA, which may have an impact on the risk of recurrence and survival
Ground State Bands of the E(5) and X(5) Critical Symmetries Obtained from Davidson Potentials through a Variational Procedure
Davidson potentials of the form , when used in
the original Bohr Hamiltonian for -independent potentials bridge the
U(5) and O(6) symmetries. Using a variational procedure, we determine for each
value of angular momentum the value of at which the derivative of
the energy ratio with respect to has a sharp maximum,
the collection of values at these points forming a band which practically
coincides with the ground state band of the E(5) model, corresponding to the
critical point in the shape phase transition from U(5) to O(6). The same
potentials, when used in the Bohr Hamiltonian after separating variables as in
the X(5) model, bridge the U(5) and SU(3) symmetries, the same variational
procedure leading to a band which practically coincides with the ground state
band of the X(5) model, corresponding to the critical point of the U(5) to
SU(3) shape phase transition. A new derivation of the Holmberg-Lipas formula
for nuclear energy spectra is obtained as a by-product.Comment: LaTeX, 12 pages, 4 postscript figure
- …