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排序方式: 共有96条查询结果,搜索用时 218 毫秒
21.
G. Costanza 《Physica A》2003,330(3-4):421-441
The analytical continuous equations for the Tang and Leschhorn (Phys. Rev. A 45 (1992) R8309) and the Buldyrev et al. (Phys. Rev. A 45 (1992) R8313) models are derived from the microscopic rules using a regularization procedure. As was shown in a previous paper (Phys. Rev. E 62 (2000) 6970) the continuous equation for the Tang and Leschhorn model is formally different to the Kardar–Parisi–Zhang equation (Phys. Rev. Lett. 56 (1986) 889) with quenched noise (QKPZ). Nevertheless, after expanding the multiplicative noise, it is shown that we recover the usual QKPZ, demonstrating analytically that both equations belong to the same universality class. 相似文献
22.
Ghulinyan M Oton CJ Gaburro Z Pavesi L Toninelli C Wiersma DS 《Physical review letters》2005,94(12):127401
We report on the observation of Zener tunneling of light waves in spectral and time-resolved transmission measurements, performed on an optical superlattice made of porous silicon. The structure was designed to have two photonic minibands, spaced by a narrow frequency gap. A gradient in the refractive index was introduced to create two optical Wannier-Stark ladders and, at a critical value of the optical gradient, tunneling between energy bands was observed in the form of an enhanced transmission peak and a characteristic time dependence of the transmission. 相似文献
23.
G. Bendiscioli T. Bressani S. Costanza P. Salvini 《The European Physical Journal A - Hadrons and Nuclei》2011,47(6):82
New data on the pion spectra measured in selected channels following the antiproton annihilation at rest on 4He are presented and discussed in the light of statistical models. 相似文献
24.
C. Anselmi F. Presciutti B. Doherty B. G. Brunetti A. Sgamellotti C. Miliani 《Applied Physics A: Materials Science & Processing》2011,104(1):401-406
This contribution focuses on an analytical evaluation of the use of cyclododecane (CDD) (C12H24) as a temporary protective coating for non-porous stone materials of cultural heritage interest. 相似文献
25.
We report findings from a classroom experiment in which each of two sections of the same Calculus 1 course at a North American research-focused university were subject to an “intervention” week, each for a different topic, during which a less-experienced instructor encouraged a much higher level of student engagement, promoted active learning (answering “clicker” questions, small-group discussions, worksheets) during a significant portion of class time and built on assigned pre-class tasks. The lesson content and analysis of the assessments were informed by existing research on student learning of mathematics and student interviews, though the interventions and assessments were also intended to be compatible with typical course practices in an attempt to appeal to practitioners less familiar with the literature. Our study provides an example of active learning pedagogy (including materials and assessment used) for students at this level of mathematics in a classroom of over one hundred students, and we report improved student performance—on conceptual items in particular—with a switching replication in that each section outperformed the other on the topic for which it received the intervention. 相似文献
26.
Costanza Conti Luca Gemignani Lucia Romani 《Advances in Computational Mathematics》2011,35(2-4):217-241
In this paper we describe a general, computationally feasible strategy to deduce a family of interpolatory non-stationary subdivision schemes from a symmetric non-stationary, non-interpolatory one satisfying quite mild assumptions. To achieve this result we extend our previous work (Conti et al., Linear Algebra Appl 431(10):1971?C1987, 2009) to full generality by removing additional assumptions on the input symbols. For the so obtained interpolatory schemes we prove that they are capable of reproducing the same space of exponential polynomials as the one generated by the original approximating scheme. Moreover, we specialize the computational methods for the case of symbols obtained by shifted non-stationary affine combinations of exponential B-splines, that are at the basis of most non-stationary subdivision schemes. In this case we find that the associated family of interpolatory symbols can be determined to satisfy a suitable set of generalized interpolating conditions at the set of the zeros (with reversed signs) of the input symbol. Finally, we discuss some computational examples by showing that the proposed approach can yield novel smooth non-stationary interpolatory subdivision schemes possessing very interesting reproduction properties. 相似文献
27.
Elisa Landucci Costanza Mazzantini Daniela Buonvicino Domenico E. Pellegrini-Giampietro Maria Camilla Bergonzi 《Molecules (Basel, Switzerland)》2021,26(6)
Experimental evidence indicates that the activation of ionotropic glutamate receptors plays an important role in neurological disorders’ models such as epilepsy, cerebral ischemia and trauma. The glutamate receptor agonist kainic acid (KA) induces seizures and excitotoxic cell death in the CA3 region of the hippocampus. Thymoquinone (TQ) is the most important component of the essential oil obtained from black cumin (Nigella sativa L.) seeds. It has many pharmacological actions including antioxidant, anti-inflammatory, and anti-apoptotic effects. TQ was used in an in vitro experimental model of primary cultures where excitotoxicity was induced. Briefly, rat organotypic hippocampal slices were exposed to 5 µM KA for 24 h. Cell death in the CA3 subregions of slices was quantified by measuring propidium iodide fluorescence. The cross-talk between TQ, ER stress and apoptotic pathways was investigated by Western blot. In untreated slices TQ (10 µM) induced a significant increase on the PSD95 levels and it decreased the excitotoxic injury induced by KA. Additionally, TQ was able to ameliorate the KA-induced increase in unfolded proteins GRP78 and GRP94 expression. Finally, TQ was able to partially rescue the reduction of the KA-induced apoptotic pathway activation. Our results suggest that TQ modulates the processes leading to post-kainate neuronal death in the CA3 hippocampal area. 相似文献
28.
Rosi F Federici A Brunetti BG Sgamellotti A Clementi S Miliani C 《Analytical and bioanalytical chemistry》2011,399(9):3133-3145
Paintings are composed of superimposed layers of inorganic and organic materials (pigments and binders). Knowledge of the
stratigraphic sequence of these heterogeneous layers is fundamental for understanding the artist’s painting technique and
for conservation issues. In this study, micro-IR mapping experiments in reflection mode have been carried out on cross-sections
taken from simulations of ancient easel paintings. The objective was to locate both organic binders and inorganic pigments.
Chemical maps have been re-constructed using the common approach based on the integration of specific infrared bands. However,
owing to the complexity of painting materials, this approach is not always applicable when dealing with broad and superimposed
spectral features and with reststrahlen or derivative-like bands resulting from acquisition in reflection mode. To overcome these limitations, principal-component
analysis has been successfully used for the re-construction of the image, extracting the relevant information from the complex
full spectral data sets and obtaining reliable chemical distributions of the stratigraphy materials. Different pigment–binder
combinations have been evaluated in order to understand limitations and strengths of the approach. Finally, the method has
been applied for stratigraphic characterization of a cross-section from a 17th century wooden sculpture identifying both the
original paint layer and the several overpaintings constituting the complex stratigraphy. 相似文献
29.
Proietti N Presciutti F Di Tullio V Doherty B Marinelli AM Provinciali B Macchioni N Capitani D Miliani C 《Analytical and bioanalytical chemistry》2011,399(9):3117-3131
A multi-technique approach was employed to study a decorated Egyptian wooden sarcophagus (XXV–XXVI dynasty, Third Intermediate
Period), belonging to the Museo del Vicino Oriente of the Sapienza University of Rome. Portable non-invasive unilateral NMR
was applied to evaluate the conservation state of the sarcophagus. Moreover, using unilateral NMR, a non-invasive analytical
protocol was established to detect the presence of organic substances on the surface and/or embedded in the wooden matrix.
This protocol allowed for an educated sampling campaign aimed at further investigating the state of degradation of the wood
and the presence of organic substances by 13C cross polarization magic angle spinning (CPMAS) NMR spectroscopy. The composition of the painted layer was analysed by optical
microscopy (OM), scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), Raman and surface enhanced (resonance)
Raman spectroscopy (SERS/SERRS), infrared and GC–MS techniques, evidencing original components such as clay minerals, Egyptian
green, indigo, natural gums, and also highlighting restoration pigments and alteration compounds. The identification of the
wood, of great value for the reconstruction of the history of the artwork, was achieved by means of optical microscopy. 相似文献
30.
In this paper we develop tools for the analysis of net subdivision schemes, schemes which recursively refine nets of bivariate continuous functions defined on grids of lines, and generate denser and denser nets. Sufficient conditions for the convergence of such a sequence of refined nets, and for the smoothness of the limit function, are derived in terms of proximity to a bivariate linear subdivision scheme refining points, under conditions controlling some aspects of the univariate functions of the generated nets. Approximation orders of net subdivision schemes, which are in proximity with positive schemes refining points are also derived. The paper concludes with the construction of a family of blending spline-type net subdivision schemes, and with their analysis by the tools presented in the paper. This family is a new example of net subdivision schemes generating C1 limits with approximation order 2. 相似文献