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981.
982.
A parameter whose coupling to a quantum probe of n constituents includes all two-body interactions between the constituents can be measured with an uncertainty that scales as 1/n3/2, even when the constituents are initially unentangled. We devise a protocol that achieves the 1/n3/2 scaling without generating any entanglement among the constituents, and we suggest that the protocol might be implemented in a two-component Bose-Einstein condensate. 相似文献
983.
984.
Sergio Luigi Cacciatori Francesco Dalla Piazza Bert Van Geemen 《Letters in Mathematical Physics》2008,85(2-3):185-193
A main issue in superstring theory are the superstring measures. D’Hoker and Phong showed that for genus two these reduce to measures on the moduli space of curves which are the product of modular forms of weight eight and the bosonic measure. They also suggested a generalisation to higher genus. We showed that their approach works, with a minor modification, in genus three and we announced a positive result also in genus four. Here we give the modular form in genus four explicitly. Recently, S. Grushevsky published this result as part of a more general approach. 相似文献
985.
Lozano-Perez S 《Micron (Oxford, England : 1993)》2008,39(3):320-328
The preparation of samples containing stress corrosion crack tips for 3D atom-probe tomography and transmission electron microscopy is of ultimate importance for understanding the mechanisms controlling crack propagation. In this paper, it will be shown that a focused ion beam machine equipped with an in situ micromanipulator is an ideal tool to systematically prepare such demanding samples. The methodology is described and discussed in detail, and several results are presented to demonstrate the potential of the technique. 相似文献
986.
Guido Cognola Monica Gastaldi Sergio Zerbini 《International Journal of Theoretical Physics》2008,47(4):898-910
Motivated by the dark energy issue, a minisuperspace approach to the stability for modified gravitational models in a four
dimensional cosmological setting is investigated. Specifically, after revisiting the f(R) case, R being the Ricci curvature, we present a stability condition around a de Sitter solution valid for modified gravitational
models of generalized type F(R,G,Q), G and Q being the Gauss-Bonnet and quadratic Riemann invariants respectively. A generalization to higher order invariants is presented. 相似文献
987.
Carsten Carstensen Sergio Conti Antonio Orlando 《Continuum Mechanics and Thermodynamics》2008,20(5):275-301
The modeling of the finite elastoplastic behaviour of single crystals with one active slip system leads to a nonconvex variational
problem, whose minimization produces fine structures. The computation of the quasiconvex envelope of the energy density involves
the solution of a nonconvex optimization problem and faces severe numerical difficulties from the presence of many local minima.
In this paper, we consider a standard model problem in two dimensions and, by exploiting analytical relaxation results for
limiting cases and the special structure of the problem at hand, we obtain a fast and efficient numerical relaxation algorithm.
The effectiveness of our algorithm is demonstrated with numerical examples. The precision of the results is assessed by lower
bounds from polyconvexity.
相似文献
988.
Fernando C. Moraes Tiago A. Silva Ivana Cesarino Marcos R. V. Lanza Sergio A. S. Machado 《Electroanalysis》2013,25(9):2092-2099
A sensitive way to determine levofloxacin using a sensor based on vertical aligned carbon nanotubes is described. The morphology and the electrochemical performance of the electrodes were characterised by atomic force microscopy, cyclic voltammetry and square wave voltammetry. A scan‐rate study and electrochemical impedance spectroscopy showed that the levofloxacin oxidation product is adsorbed on the electrode surface. Differential pulse voltammetry in phosphate‐buffer solution allowed the development of a method to determine levofloxacin levels in the range of 1.0–10.0 µmol L?1, with a detection limit of 75.2 nmol L?1. The proposed sensor was successfully applied in the determination of levofloxacin in urine, and the obtained results were in full agreement with those from the HPLC procedure. 相似文献
989.
Joseph W. Nichols Johan Larsson Matteo Bernardini Sergio Pirozzoli 《Theoretical and Computational Fluid Dynamics》2017,31(1):33-50
The dynamics of oblique shock wave/turbulent boundary layer interactions is analyzed by mining a large-eddy simulation (LES) database for various strengths of the incoming shock. The flow dynamics is first analyzed by means of dynamic mode decomposition (DMD), which highlights the simultaneous occurrence of two types of flow modes, namely a low-frequency type associated with breathing motion of the separation bubble, accompanied by flapping motion of the reflected shock, and a high-frequency type associated with the propagation of instability waves past the interaction zone. Global linear stability analysis performed on the mean LES flow fields yields a single unstable zero-frequency mode, plus a variety of marginally stable low-frequency modes whose stability margin decreases with the strength of the interaction. The least stable linear modes are grouped into two classes, one of which bears striking resemblance to the breathing mode recovered from DMD and another class associated with revolving motion within the separation bubble. The results of the modal and linear stability analysis support the notion that low-frequency dynamics is intrinsic to the interaction zone, but some continuous forcing from the upstream boundary layer may be required to keep the system near a limit cycle. This can be modeled as a weakly damped oscillator with forcing, as in the early empirical model by Plotkin (AIAA J 13:1036–1040, 1975). 相似文献
990.
Pierfrancesco Bravo Calimero Ticozzi Sergio Daolio Pietro Traldi 《Journal of mass spectrometry : JMS》1985,20(12):740-747
The mass spectrometric behaviour of two pairs of isomeric 2,2-dimethylpyrano[3,2-c][1]benzopyran-5-ones (pyranocoumarins) and 2,2-dimethylpyrano[2,3-b][1]benzopyran-5-ones (pyranochromones) and four pairs of isomeric 2-hydroxymethyl-2-methylpyrano[3,2-c][1]benzopyran-5-ones (pyranocoumarins) and 2-hydroxymethyl-2-methylpyrano[2,3-b][1] benzopyran-5-ones (pyranochromones) has been studied in detail with the aid of exact mass measurements, linked scans, collisionally activated decompositions and deuterium labelling experiments. The presence in both series of compounds of the same ions derived by structural interconversion of both molecular ions is emphasized, and structural information on the ions [C7H5O2]+ (m/z 121), highly characteristic for these classes of compounds, as for 4-hydroxycoumarins, is reported. 相似文献