Search results for "MAGNITUDE"
showing 10 items of 501 documents
Studies towards a directional polychromatic sodium laser guide star
2018
In this work we discuss a mechanism for generation of a coherent source of light from the mesosphere as a new concept of directional laser guide star. In contrast to the near-isotropic spontaneous emission, nonlinear processes in atomic vapors like amplified spontaneous emission can yield highly directional emission in the forward and backward directions. Along with directional emission, excited sodium atoms also radiate at different wavelength creating a polychromatic laser guide star (PLGS). If feasible, a directional PLGS would provide a net gain in the return flux of several orders of magnitude compared to traditional LGS schemes, making possible laser-guided tip/tilt-correction in adap…
Additives for vaccine storage to improve thermal stability of adenoviruses from hours to months
2016
Up to 80% of the cost of vaccination programmes is due to the cold chain problem (that is, keeping vaccines cold). Inexpensive, biocompatible additives to slow down the degradation of virus particles would address the problem. Here we propose and characterize additives that, already at very low concentrations, improve the storage time of adenovirus type 5. Anionic gold nanoparticles (10−8–10−6 M) or polyethylene glycol (PEG, molecular weight ∼8,000 Da, 10−7–10−4 M) increase the half-life of a green fluorescent protein expressing adenovirus from ∼48 h to 21 days at 37 °C (from 7 to >30 days at room temperature). They replicate the known stabilizing effect of sucrose, but at several orders of…
Efficient Linear-Scaling Density Functional Theory for Molecular Systems
2013
Despite recent progress in linear scaling (LS) density function theory (DFT), the computational cost of the existing LS methods remains too high for a widespread adoption at present. In this work, we exploit nonorthogonal localized molecular orbitals to develop a series of LS methods for molecular systems with a low computational overhead. High efficiency of the proposed methods is achieved with a new robust two-stage variational procedure or by replacing the optimization altogether with an accurate nonself-consistent approach. We demonstrate that, even for challenging condensed-phase systems, the implemented LS methods are capable of extending the range of accurate DFT simulations to molec…
The large trans-Neptunian object 2002 TC 302 from combined stellar occultation, photometry, and astrometry data
2020
All authors: Ortiz, J. L.; Santos-Sanz, P.; Sicardy, B.; Benedetti-Rossi, G.; Duffard, R.; Morales, N.; Braga-Ribas, F.; Fernández-Valenzuela, E.; Nascimbeni, V.; Nardiello, D.; Carbognani, A.; Buzzi, L.; Aletti, A.; Bacci, P.; Maestripieri, M.; Mazzei, L.; Mikuz, H.; Skvarc, J.; Ciabattari, F.; Lavalade, F. Scarfi, G.; Mari, J. M.; Conjat, M.; Sposetti, S.; Bachini, M.; Succi, G.; Mancini, F.; Alighieri, M.; Dal Canto, E.; Masucci, M.; Vara-Lubiano, M.; Gutiérrez, P. J.; Desmars, J.; Lecacheux, J.; Vieira-Martins, R.; Camargo, J. I. B.; Assafin, M.; Colas, F.; Beisker, W.; Behrend, R.; Mueller, T. G.; Meza, E.; Gomes-Junior, A. R.; Roques, F.; Vachier, F.; Mottola, S.; Hellmich, S.; Campo …
ON THE CALCULATION OF THE HEAT CAPACITY IN PATH INTEGRAL MONTE CARLO SIMULATIONS
1992
In Path Integral Monte Carlo simulations the systems partition function is mapped to an equivalent classical one at the expense of a temperature-dependent Hamiltonian with an additional imaginary time dimension. As a consequence the standard relation linking the heat capacity Cv to the energy fluctuations, <E2>−<E>2, which is useful in standard classical problems with temperature-independent Hamiltonian, becomes invalid. Instead, it gets replaced by the general relation [Formula: see text] for the intensive heat capacity estimator; β being the inverse temperature and the subscript P indicates the P-fold discretization in the imaginary time direction. This heatcapacity estimator…
A regional analysis of the effects of largest events on soil erosion
2012
A large amount of geomorphic work is caused by a small number of extreme events that are mainly responsible for the time compression of geomorphic processes. The classic approach defines extreme events by their magnitude and they are quantified by certain deviation from a central value. Alternatively, we define extreme events as the largest events sorted by rank, whatever their absolute magnitude. In this case, events with equal rank from two different sites can be responsible for different magnitudes of geomorphic work, e.g., the amount of erosion. The new approach applied to soil erosion is that, whatever the magnitude of soil eroded, erosion is a time compressed process and the percentag…
A parametric description of the 3D structure of the Galactic bar/bulge using the VVV survey
2017
We study the structure of the inner Milky Way using the latest data release of the Vista Variables in Via Lactea (VVV) survey. The VVV is a deep near-infrared, multi-colour photometric survey with a coverage of 300 square degrees towards the Bulge/Bar. We use Red Clump (RC) stars to produce a high-resolution dust map of the VVV's field of view. From de-reddened colour-magnitude diagrams we select Red Giant Branch stars to investigate their 3D density distribution within the central 4 kpc. We demonstrate that our best-fit parametric model of the Bulge density provides a good description of the VVV data, with a median percentage residual of 5$\%$ over the fitted region. The strongest of the o…
DISTRIBUTION OF CARBON STARS IN THE GALAXY
2018
A search for new faint carbon (C) stars in the Polar region δ > 55o has been accomplished by obtaining objective prism spectra in the near infrared 550 -- 900 nm on images of CCD camera of Baldone Schmidt telescope of Astrophysical observatory. The positions of stars having color indices (J – K) > 1.3 mag in Two Micron All Sky Infrared Survey (2MASS) were selected to pick out suspicious carbon stars.Our survey is limited in brightness by J < 10 mag. 24 new carbon stars were found and their characteristics obtained. The correlative relation between Teff and spectral gradient [757 – 685] was confirmed. Such characteristics as Teff, distance from the Sun, absolute Mk were obtained…
Absolute measurement of quadratic nonlinearities from phase-matched second-harmonic generation in a single KTP crystal cut as a sphere
1997
We determine within an accuracy of ∼10% the absolute magnitude of the quadratic effective coefficients of types I and II phase-matched second-harmonic generation from conversion efficiency measurements in a single nonlinear crystal cut as a sphere. The agreement is good with measurements performed in thin parallelepipedal samples. The material studied is KTiOPO4, for which improved Sellmeier equations are given.
Dynamic mean absolute error as new measure for assessing forecasting errors
2018
Abstract Accurate wind power forecast is essential for grid integration, system planning, and electricity trading in certain electricity markets. Therefore, analyzing prediction errors is a critical task that allows a comparison of prediction models and the selection of the most suitable model. In this work, the temporal error and absolute magnitude error are simultaneously considered to assess the forecast error. The trade-off between both types of errors is computed, analyzed, and interpreted. Moreover, a new index, the dynamic mean absolute error, DMAE, is defined to measure the prediction accuracy. This index accounts for both error components: temporal and absolute. Real cases of wind …