Dark Energy： Relating the Evolutions of the Universe from the Past to the Future

Using the evolution history of the universe, one can make constraint on the parameter space of dynamic dark energy models. We discuss two different parameterized dark energy models. Our results further restrict the combined constraints obtained from supernova and the first-year Wilkinson-microwave-anisotropy-probe observations. From the allowed parameter space, it is found that our universe will experience an eternal acceleration. We also estimate the bound on the physically relevant regions both in the re-inflationary and inflationary phases.     

Can the CMB reveal the topology of the universe?

This article summarizes recent progress in the development of tools to study the topology of the universe with the cosmic microwave background. The different signatures of the topology and observational constraints are described. The ability of future experiments to reveal the topological structure of our universe is then discussed. To cite this article: J.P. Uzan, A. Riazuelo, C. R. Physique 4 (2003).     

Telecommunications—the state of the art

This article is a survey of the technological foundations of telecommunications, including both point-to-point electrical communication wing wires, cables and other guiding media. and radio wave broadcasting to many receivers via terrestrial transmitters or Earth-orbiting space satellites. The characteristics of analogue and digital telecommunication signals, the means available for their transmission and switching me described, together with the organization of local distribution, national and global networks. The various services that can be provided over such networks, including in addition to telephonic communication, audio and video conferencing, data and facsimile transmission and new vied-display data/information access services (Teletext) are outlined. Finally, the sociological implications of these technological and service developments me considered, for example in terms of their impact on urban and rural planning, where people live and work, and on energy economy by reducing the need to travel.     

On the interpretation of the results of the experimental test of the Askar’yan effect

The effect of the environment on the results of measuring the radio radiation spectrum is considered in the experimental simulation of the cascade shower by a high-energy γ-ray beam in a dense medium. The calculation shows that the character of the measured energy spectrum depends on the location of the receiving antenna with respect to the shower axis.     

Why is the Euclidean Line the Same as the Real Line?

This paper investigates whether the differential structure of space-time follows from accepted laws of physics, or is a mathematical invention. In view of the results of [7], it suffices to consider whether the assumed identity of the Euclidean line E—the line of the geometers of ancient Greece—and the real line R of modern analysis, follows from any known law of nature (i.e., one that can be falsified empirically). Since the totality of empirical data is finite, one is forced to conclude that the completeness of R cannot be falsified empirically—and therefore, according to Popper's criterion, the real line must be an invention, and not a discovery. It then becomes difficult to tell whether Newton's second law of motion (expressed as the differential equation is an invention or a discovery! Finally, some alternatives to the above analysis are briefly analysed.     

On the connection between the solutions to the Dirac and Weyl equations and the corresponding electromagnetic four-potentials

In this work we study in detail the connection between the solutions to the Dirac and Weyl equations and the associated electromagnetic four-potentials.First,it is proven that all solutions to the Weyl equation are degenerate,in the sense that they correspond to an infinite number of electromagnetic four-potentials.As far as the solutions to the Dirac equation are concerned,it is shown that they can be classified into two classes.The elements of the first class correspond to one and only one four-potential,and are called non-degenerate Dirac solutions.On the other hand,the elements of the second class correspond to an infinite number of four-potentials,and are called degenerate Dirac solutions.Further,it is proven that at least two of these fourpotentials are gauge-inequivalent,corresponding to different electromagnetic fields.In order to illustrate this particularly important result we have studied the degenerate solutions to the forcefree Dirac equation and shown that they correspond to massless particles.We have also provided explicit examples regarding solutions to the force-free Weyl equation and the Weyl equation for a constant magnetic field.In all cases we have calculated the infinite number of different electromagnetic fields corresponding to these solutions.Finally,we have discussed potential applications of our results in cosmology,materials science and nanoelectronics.     

Study on the optical system for the record of the pulsed acoustic field and the scattering of the cylindrical-like objects buried in underwater sand

11尬roductlon For the vlsuallzatlon and the studies of the physical properties of acoustic ield;the schlierentechnique was the most useful for the co尬Inuous waves[1,2].ReceNwars,the shadowgraphmode was appeared for the recording of＊theing acoustic pulse[3-p].Although the shadowgr地hmode Is used more frequently In experimental fluid dynamics[6],In the irst part of this paper;the response of＊these opticall扯enslty of＊the recorded acoustic pulse related to the acousticpressure gradlem Is st…     

Variation in the structural state of the α-phase in the Pd-In-H system during the β → α transformation

Increasing the concentration of indium atoms and hydrogen was found in the α-phase of the foil of a Pd-In alloy (with 5.3 and 5.0 at % In) after its electrolytic hydrogenation and 500-h relaxation. It is shown that the structural variations in the foil during the β → α transformation are nonmonotonic.     

A New Approach to the Justification of the Wolkenstein–Ptitsyn Formula for the Parameter of the Vitrification Equation

Technical Physics - An extended interpretation of the Wolkenstein–Ptitsyn formula for temperature band δTg, characterizing a range of transition from liquid to glass, is considered using...     

Does the market maker stabilize the market?

The market maker plays an important role in price formation, but his/her behavior and stabilizing impact on the market are relatively unclear, in particular in speculative markets. This paper develops a financial market model that examines the impact on market stability of the market maker, who acts as both a liquidity provider and an active investor in a market consisting of two types of boundedly rational speculative investors—the fundamentalists and trend followers. We show that the market maker does not necessarily stabilize the market when he/she actively manages the inventory to maximize profits, and that rather the market maker’s impact depends on the behavior of the speculators. Numerical simulations show that the model is able to generate outcomes for asset returns and market inventories that are consistent with empirical findings.     

On the Structure of the B¨acklund Transformations for the Relativistic Lattices

Abstract

The B¨acklund transformations for the relativistic lattices of the Toda type and their discrete analogues can be obtained as the composition of two duality transformations. The condition of invariance under this composition allows to distinguish effectively the integrable cases. Iterations of the B¨acklund transformations can be described in the terms of nonrelativistic lattices of the Toda type. Several multifield generalizations are presented.     

On the Scattering of the Electron off the Hydrogen Atom and the Helium Ion Below and Above the Ionization Threshold: Temkin–Poet Model

We generalize here the splitting approach to the long range (Coulomb) interaction for the three body scattering problem. With this approach, the exterior complex rotation technique can be applied for systems with asymptotic Coulomb interaction. We illustrate the method with calculations of the electron scattering on the hydrogen atom and positive helium ion in the frame of the Temkin–Poet model.     

On the polynomial τ-functions for the KP hierarchy and the bispectral property

We show that the -functions obtained from Schur polynomials lead to wave functions w(x ₁, x ₂, ... ; k) that possess the following bispectral property: There exists a differential operator B{k,_k}, independent of x ₁ , such that B{k,_k}w = {x ₁}w, where {x ₁} is independent of k. This extends for the KP hierarchy some earlier results of J. J. Duistermaat and F. A. Grünbaum for the rational solutions of KdV and of P. Wright for certain rational solutions of the generalized KdV equations.     

Influence of the Investor’s Behavior on the Complexity of the Stock Market

One of the pillars of the finance theory is the efficient-market hypothesis, which is used to analyze the stock market. However, in recent years, this hypothesis has been questioned by a number of studies showing evidence of unusual behaviors in the returns of financial assets (“anomalies”) caused by behavioral aspects of the economic agents. Therefore, it is time to initiate a debate about the efficient-market hypothesis and the “behavioral finances.” We here introduce a cellular automaton model to study the stock market complexity, considering different behaviors of the economical agents. From the analysis of the stationary standard of investment observed in the simulations and the Hurst exponents obtained for the term series of stock index, we draw conclusions concerning the complexity of the model compared to real markets. We also investigate which conditions of the investors are able to influence the efficient market hypothesis statements.     

On the fictitious nonlinearity of the surface impedance of the Earth’s crust

The observations of Alfvén oscillations of the magnetosphere are used to study the Earth’s crust and upper mantle by the magnetotelluric sounding method. The sounding procedure involves the measurement of the horizontal components of the electromagnetic field at a given point on the ground, the calculation of the surface impedance, and the determination of the conductivity of rocks from these data. It has been shown that the anharmonicity of the oscillations of the magnetosphere in combination with the nonlocality of the boundary condition on the ground gives rise to the amplitude dependence of the impedance calculated using the classical magnetotelluric sounding method. This apparent nonlinearity of the impedance can be manifested in the sounding of the Earth’s interior with intense electromagnetic pulsations, which appear when the Earth’s magnetosphere is embedded in the highspeed solar wind flow.     

Do the seagull terms really survive for the electric polarizability of the nucleon?

The seagull terms for the electric polarizability of the nucleon are shown indeed to vanish, if one introduces fluctuations around the Skyrmion configuration, and the origin of the electric polarizability cannot after all be attributed to the seagull terms in the Skyrme model.     

Characteristics of the internal waves and their effects on the sound transmission in the Midst of the Yellow Sea

1IntroductionInternalwavesarefoundthroughouttheworld's...an[1-3].Theactivityofinternalwavescausesthechangesofthesoundspeedprofile,andthereforeaffectsthesoundpropagation['].Duringthepastdecades,considerableprogresshasbeenmadeinunderstandinginternaIwavesandtheireffectsonsoundindeepocean.Nowtheresearchcommunityhasshiftedtheemphasistoshallowwaterarea[5~l1].Inthelatesummerof1996,scientistsfromChinaandtheUnitedStatesconductedacombinedacousticsandphysicaloceanographyexperimentintheYellowSea(YS96)…