Planar superstrate for dual-frequency RHCP-LHCP array

Patch antennas are low profile, lightweight and most suitable for aerospace and mobile applications. In recent years Fabry–Pérot cavities and meta-surfaces have been used as superstrates to improve the radiation performance of planar antennas (Saenz et al., IEEE Trans. Antennas Propag. 56(4), 2008; Iriarte et al., IEEE Trans. Antennas Propag. 57(1), 2009) such as directivity, mutual coupling on array configuration and bandwidth. These structures usually work for a single polarization and frequency band, while an increasing number of applications require multifrequency operation. In this paper a Fabry–Pérot cavity that works with dual-polarized and dual-frequency patch antennas (rectangular patch excited orthogonally) is proposed in order to design high-directivity dual-frequency RHCP-LHCP Arrays.     

Spectral Action on <Emphasis Type="Italic">SU</Emphasis><Subscript><Emphasis Type="Italic">q</Emphasis></Subscript>(2)

The spectral action on the equivariant real spectral triple over is computed explicitly. Properties of the differential calculus arising from the Dirac operator are studied and the results are compared to the commutative case of the sphere . UMR 6207, – Unité Mixte de Recherche du CNRS et des Universités Aix-Marseille I, Aix-Marseille II et de l’Université du Sud Toulon-Var, Laboratoire affilié à la FRUMAM – FR 2291. Partially supported by Polish Government grants 189/6.PRUE/2007/7; 115/E-343/SPB/6.PR UE/DIE and N 201 1770 33.     

Polyakov Soldering and Second-Order Frames: The Role of the Cartan Connection

The so-called ‘soldering’ procedure performed by Polyakov (Int J Math Phys A5, 833–842, 1990) for a -gauge theory is geometrically explained in terms of a Cartan connection on second-order frames of the projective space P¹. The relationship between a Cartan connection and the usual (Ehresmann) connection on a principal bundle allows to gain an appropriate insight into the derivation of the genuine ‘diffeomorphisms out of gauge transformations’ given by Polyakov himself. Unité Mixte de Recherche (UMR 6207) du CNRS et des Universités Aix-Marseille I, Aix-Marseille II et de l’Université du Sud Toulon-Var. Unité affiliée à la FRUMAM Fédération de Recherche 2291.     

On the experimental verification of the Landau-Pomeranchuk-Migdal effect

A theoretical explanation is given for the “unexpected” behavior recently observed in the radiation spectrum of ultrarelativistic electrons in a thin layer of matter in an experimental investigation of the Landau-Pomeranchuk-Migdal effect at SLAC [S. R. Klein et al., Preprint SLAC-6378, Stanford (1993); P. L. Anthony et al., Phys. Rev. Lett. 75, 1949 (1995)]. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 11, 837–840 (10 June 1996)     

Strominger–Yau–Zaslow Geometry,Affine Spheres and Painlevé III

We give a gauge invariant characterisation of the elliptic affine sphere equation and the closely related Tzitzéica equation as reductions of real forms of anti–self–dual Yang–Mills equations by two translations, or equivalently as a special case of the Hitchin equation. We use the Loftin–Yau–Zaslow construction to give an explicit expression for a six–real dimensional semi–flat Calabi–Yau metric in terms of a solution to the affine-sphere equation and show how a subclass of such metrics arises from 3^rd Painlevé transcendents.     

Phonon–phonon interactions due to non-linear effects in a linear ion trap

We examine in detail the theory of the intrinsic non-linearities in the dynamics of trapped ions due to the Coulomb interaction. In particular, the possibility of mode–mode coupling, which can be a source of decoherence in trapped ion quantum computation, or can be exploited for parametric down-conversion of phonons, is discussed and conditions under which such coupling is possible are derived. Received: 8 November 2002 / Published online: 26 March 2003 RID="*" ID="*"Permanent address: MIP, Université Pierre et Marie Curie and Département de Physique, école Normale Supérieure, 75005 Paris, France RID="**" ID="**"Corresponding author. Fax: +1-505/667-1931, E-mail: dfvj@lanl.gov     

Anomalous burn-through of thin foils by high-intensity laser radiation

The paper presents results of experiments performed on the Pico facility in which foils were heated by laser radiation, and anomalously fast burn-through of foils by a structured laser beam was detected. Comparison with two-dimensional calculations has allowed us to suggest a tentative mechanism for the effect under investigation. The targets in the experiments were thin aluminum foils of thickness 3 to 40 μm. The flux density of laser radiation on the target surface varied between 10¹³ and 10¹⁴ W/cm². We detected a strong dependence of the transmitted energy on the foil thickness and the shortening of the transmitted laser pulse. Penetration of laser radiation through foils with thicknesses considerably larger than 3 μm has been observed, although it was stated in earlier publications [V. V. Ivanov, A. K. Knyazev, A. V. Kutsenko, et al., Kratk. Soobshch. Fiz. FIAN No. 7–8, 37 (1997)]; A. é. Bugrov, I. N. Burdonskii, V. V. Gol’tsov et al., Zh. éksp. Teor. Fiz. 111, 903 (1997) [JETP 84, 903 (1997)] that, at the laser radiation parameters used in our experiment, the evaporated layer of the foil could not be thicker than 2 μm. Two-dimensional calculations have allowed us to interpret this effect in terms of local “piercing” of the target at spots on the target surface where the radiation intensity has its peaks. The possibility of reducing these peaks by using a symmetrizing prepulse is discussed in the paper. Zh. éksp. Teor. Fiz. 116, 1287–1299 (October 1999)     

Experimental investigation of the characteristic features of bremsstrahlung from high-energy electrons in thin amorphous targets

Radiation from 0–900 MeV electrons in thin amorphous films is investigated experimentally in the photon energy range 20–700 keV. The Landau-Pomeranchuk-Migdal suppression of the soft part of the bremsstrahlung spectrum and the Ter-Mikaélyan density effect are detected. Coherent bremsstrahlung on macroscopic inhomogeneities in the target material is observed. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 5, 369–373 (10 March 1997)     

Random Unitary Matrices, Permutations and Painlevé

This paper is concerned with certain connections between the ensemble of n×n unitary matrices – specifically the characteristic function of the random variable tr(U) – and combinatorics – specifically Ulam's problem concerning the distribution of the length of the longest increasing subsequence in permutation groups – and the appearance of Painlevé functions in the answers to apparently unrelated questions. Among the results is a representation in terms of a Painlevé V function for the characteristic function of tr(U) and (using recent results of Baik, Deift and Johansson) an expression in terms of a Painlevé II function for the limiting distribution of the length of the longest increasing subsequence in the hyperoctahedral groups. Received: 2 December 1998 / Accepted: 12 May 1999     

Anomalous Pulsation

Subordinating regular diffusion – namely, Brownian motion – to random time flows generated by Lévy noises may result in anomalous diffusion. Motivated by this phenomena, and by the recent interest in the phenomena of blinking in various physical systems, we explore the subordination of regular stochastic pulsation – namely, Poisson process – to random time flows generated by Lévy noises. We show that such subordination may yield, analogous to the case of diffusion, anomalous pulsation. Anomalous pulsation displays the following anomalous behaviors, which are impossible in the case of regular pulsation: (i) simultaneous emission of multiple pulses; (ii) non-linear local pulsation rates; (iii) clustering of pulsation epochs.     

Poincaré’s Relativistic Physics: Its Origins and Nature

Henri Poincaré (1854–1912) developed a relativistic physics by elevating the empirical inability to detect absolute motion, or motion relative to the ether, to the principle of relativity, and its mathematics ensured that it would be compatible with that principle. Although Poincaré’s aim and theory were similar to those of Albert Einstein (1879–1955) in creating his special theory of relativity, Poincaré’s relativistic physics should not be seen as an attempt to achieve Einstein’s theory but as an independent endeavor. Poincaré was led to advance the principle of relativity as a consequence of his reflections on late nineteenth-century electrodynamics; of his conviction that physics should be formulated as a physics of principles; of his conventionalistic arguments on the nature of time and its measurement; and of his knowledge of the experimental failure to detect absolute motion. The nonrelativistic theory of electrodynamics of Hendrik A.Lorentz (1853–1928) of 1904 provided the means for Poincaré to elaborate a relativistic physics that embraced all known physical forces, including that of gravitation. Poincaré did not assume any dynamical explanation of the Lorentz transformation, which followed from the principle of relativity, and he did not seek to dismiss classical concepts, such as that of the ether, in his new relativistic physics. Shaul Katzir teaches in the Graduate Program in History and Philosophy of Science, Bar Ilan University.     

On the spontaneous-coherence-transfer-induced sign change of a sub-natural-width nonlinear resonance

A simple theoretical model is proposed which describes the positive sign of the nonlinear absorption resonances in the experiments of Akul’shin et al. [Phys. Rev. A 57, 2996 (1998)]. An analytical expression for the linear response to a weak probe field is obtained in the weak-saturation limit. It is shown that the positive sign of sub-natural-width resonances is due to the spontaneous transfer of low-frequency coherence from an excited level to the ground state. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 11, 776–781 (10 June 1999)     

Polymers from C60 barrelenes

Dimer, trimer, and chain structures consisting of covalently joined barrel-shaped C₆₀ monomers (barrelenes) with different types of bonds are modeled. The computed distances between the centers of the molecules within a barrelene chain (0.70–0.74 nm) and between the symmetry axes of the chains (0.63–0.77 nm) are comparable to the analogous distances on the surface of fullerites synthesized by Davydov’s group [V. A. Davydov, L. S. Koshevarova, A. V. Rakhmanina et al., JETP Lett. 63, 818 (1996)] and subjected to high pressures (∼10 GPa) and heating (∼700 K). The formation of special two-dimensional structures (triangles, squares, chains with a kink, stars), which are observed experimentally, is explained on the basis of the model, and 3D polymer structures consisting of C₆₀ barrelenes with density close to that of samples obtained earlier are constructed. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 9, 678–683 (10 May 1998)     

A response to Murshed et al., J Nanopart Res (2010) 12:2007–2010

This brief communication provides a response to Murshed et al. (J Nanopart Res 12:2007–2010, 2010). We acknowledge that three of the equations in our original article (Doroodchi et al. J Nanopart Res 11:1501–1507, 2009) contained minor typographical errors. However, we confirm that these misprinted equations have no bearing on the results presented within that article. In addition, we would like to clarify that we do not challenge the methodology of Leong et al. (J Nanopart Res 8:245–254, 2006). Instead, we repeated their analysis using a more general form for the temperature field with continuity imposed across the particle–nanolayer–liquid interfaces and found that the solution reduces to the Renovated-Maxwell model.     

<Emphasis Type="Italic">C</Emphasis><Subscript>1</Subscript> non-integrability of a hydrogen atom in a circularly polarized microwave field

Barrabés et al. [Physica D, 241(4), 333–349, 2012] consider the problem of the hydrogen atom interacting with a circularly polarized microwave field modeled as a planar perturbed Kepler problem. For different values of the parameter, the authors offer some numerical evidence of the non-integrability of this problem. The objective of the present work is to give an analytical proof of the C1 non-integrability of this problem for any value of the parameter using the averaging theory as a main tool.     

Large scale synthesis of silicon nanowires

Artificial nanostructures (Samuelson et al., Physica E 21:560–567, 2004; Xia et al., Adv Mater 15:353–389, 2003) show promise for the organization of functional materials (Huck and Samuelson, Nanotechnology 14:NIL_5–NIL_8, 2003) to create nanoelectronic (Mizuta and Oda, Science 279:208–211, 2008) or nano-optical devices (Mazur et al.; Tanemura et al., Synthesis, Optical Properties and Functional Applications of ZnO Nano-materials: A Review, 1–3:58–63, 2008). However, in most manufacturing recipes described so far, nanostructures are synthesized in solution and/or uncontrolled deposition results in random arrangements; this makes it difficult to measure the properties of attached nanodevices or to integrate them with conventionally fabricated microcircuitry. Here, we describe a fully CMOS compatible process technology for mass manufacture of polysilicon nanowires by the CVD (chemical vapor deposition) method. The large scale production of nanowires could successfully be synthesized on silicon (100) substrates. However, the method presented here can successfully be employed with all technologically useful substrates with good adhesion for silicon such as SiO₂, diamond-like carbon or III–V semiconductors. This opens up the possibility for the fabrication of strain-sensitive and defect-sensitive optoelectronic devices on the optimum III–V substrate (Fonstad et al.). Finally, scanning electron microscopy (SEM) was used to characterize the as-synthesized nanowires and energy-filtered transmission electron microscopy (EFTEM) and scanning transmission electron microscopy (STEM) analysis were used to determine the nanowire composition.     

From effective BCS action to vortex dynamics

The topological term in the effective action for the electrically neutral BCS system is discussed. It is applied for the calculation of the transverse force acting on a vortex in the limit of a smooth vortex core and vanishing interlevel distance in the vortex core. The controversy between the topological terms in the articles by I. J. R. Aitchison et al., Phys. Rev. B 51, 6531 (1995) and A. van Otterlo et al., cond-mat/9703124 is resolved. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 8, 641–646 (25 April 1997) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Generalized Euler–Poincaré Equations on Lie Groups and Homogeneous Spaces,Orbit Invariants and Applications

We develop the necessary tools, including a notion of logarithmic derivative for curves in homogeneous spaces, for deriving a general class of equations including Euler–Poincaré equations on Lie groups and homogeneous spaces. Orbit invariants play an important role in this context and we use these invariants to prove global existence and uniqueness results for a class of PDE. This class includes Euler–Poincaré equations that have not yet been considered in the literature as well as integrable equations like Camassa–Holm, Degasperis–Procesi, μCH and μDP equations, and the geodesic equations with respect to right-invariant Sobolev metrics on the group of diffeomorphisms of the circle.     

Proton-phonon coupling in a hydrogen bonded system

The Hamiltonian for the dynamics of a structural defect in a linear hydrogen bonded system (e.g., one analogous to an excess proton in ice) is developed, including explicit expressions for the coupling between the defect and phonons. The nature of these couplings are discussed and the results of a minimal basis set SCF calculation on a model system presented. The coupling to the longitudinal phonons is found to be very strong.

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Zusammenfassung Der Hamiltonoperator für die Dynamik eines Strukturdefektes in einem linearen System von Wasserstoffbrückenbindungen (etwa analog dem Excessproton in Eis) wird entwickelt samt expliziten Ausdrücken für die Kopplungen zwischen dem Defekt und den Phononen. Die Natur dieser Kopplungen wird diskutiert und die Ergebnisse einer SCF-Rechnung mit minimaler Basis an einem Modell-System dargelegt. Die Kopplung zu den longitudinalen Phononen stellt sich als sehr stark heraus.

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Résumé On a développé l’Hamiltonien de la dynamique d’un défaut structurel dans un système linéaire de liaisons hydrogène (par exemple, un défaut produit dans de la glace par un proton excessif). On a tenu compte explicitement des couplages entre le défaut et les phonons. On a discuté de la nature de ces couplages et on a présenté, pour un système modèle les résultats d’un calcul opérant sur un “self consistent field” (SCF) à ensemble minimal de bases vectorielles. Il s’est révélé que le couplage aux phonons longitudinaux est particulièrement fort.