Canonical property of the Miura maps between the MKP and KP hierarchies,continuous and discrete

Apart from the case of the KP hierarchy, all known Miura maps between integrable Hamiltonian systems had been proven to be canonical. The remaining KP case is settled below. As a corollary, it is shown that the KP hierarchy is a factor — hierarchy of the mKP one, with the kernel consisting of a single scalar field. A discrete mKP hierarchy and the associated Miura map are constructed, and the latter is shown to be canonical as well. As in the continuous case, this implies that one can extend the discrete KP hierarchy by a single new field into an extended discrete KP hierarchy in such a way that the extended discrete Miura map mKPeKP is a canonical isomorphism.     

On asymptotic cones and quasi-isometry classes of fundamental groups of 3-manifolds

We apply the concept of asymptotic cone to distinguish quasi-isometry classes of fundamental groups of 3-manifolds. We prove that the existence of a Seifert component in a Haken manifold is a quasi-isometry invariant of its fundamental group.This research was partially supported by the grant SFB 256 Nichtlineare partielle Differentialgleichungen and the NSF grant DMS-9306140 (Kapovich).     

Determination of the atmospheric neutrino spectra with the Fréjus detector

The combined analysis of the final event set of data on neutrino interactions inside the detector, upward going stopping muons and horizontal muons recorded in the Fréjus experiment is presented. The absolute atmospheric neutrino spectra in the energy range for electron neutrinos and for muon neutrinos are determined. Based on the parameterization of Volkova for thev ^µ a spectral index of =2.66±0.05 is obtained from the ratio of horizontal muons over upward going stopping muons and from the measurement of the energy loss of horizontal muons inside the detector. The neutrino spectra are compared with various flux calculations. They do not show any evidence for neutrino oscillations in agreement with earlier analyses of the Fréjus data.Now atUniversity of Michigan, Ann Arbor, USA     

Full-wave analysis of waveguide-to-microstrip transitions for millimeter wave applications

A full-wave solution is presented for the waveguide to microstrip transition. The exact Green's function of the transition is used in a moment method procedure. The behavior of the microstrip transition to a rectangular waveguide is studied with respect to the critical dimensions of the microstrip width, length and backshort location. The convergence characteristics of the full wave analysis method are investigated, along with the current distribution and the input impedance. Results given for the return loss is compared with measurements.     

Piezoelectric sound generation and detection at 70 GHz using the technique of linear frequency modulation of a continuous wave

The method of linear frequency modulation of a continuous wave (FM-CW) in sound-echo experiments is demonstrated at a sound frequency of 70 GHz. A reflex klystron with a cw power of only 300 mW and a planar Hertzian resonator are used for the piezoelectric sound excitation. Applying homodyne detection, spectral echo signals are detected in the kHz range by means of a spectral analyzer. The detected echoes show an excellent signal-to-noise ratio. Details of the experimental setup and the underlying theory of the FM-CW sound experiments are presented. We observe experimentally two excited needle-like sound beams in 65 m distance, each about 30 m in diameter.     

Luminescence centers in porous silicon

Photoluminescence studies on porous silicon show that there are luminescence centers present in the surface states. By taking photoluminescence spectra of porous silicon with respect to temperature, a distinct peak can be observed in the temperature range 100–150 K. Both linear and nonlinear relationships were observed between excitation laser power and the photoluminescence intensity within this temperature range. In addition, there was a tendency for the photoluminescence peak to red shift at low temperature as well as at low excitation power. This is interpreted as indicating that the lower energy transition becomes dominant at low temperature and excitation power. The presence of these luminescence centers can be explained in terms of porous silicon as a mixture of silicon clusters and wires in which quantum confinement along with surface passivation would cause a mixing of andX band structure between the surface states and the bulk. This mixing would allow the formation of luminescence centers.     

Some properties of higher-order Darboux transformations

We introduce the operator of the Darboux transformation of order n as an nth-order differential operator transforming the solution of the one-dimensional Schrödinger equation with a given potential into the solution corresponding to a different potential. For n=1 we obtain the usual Darboux transformation. It is shown that when n1 this transformation can always be represented as a product of n first-order Darboux transformations. We discuss the relationship between higher-order Darboux transformations and the supersymmetric approach to quantum mechanics and also the algebra of the dynamical symmetry of the system.Tomsk State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 3–8, July, 1995.     

Radionuclide partitioning coefficients in the Sava River ecosystem

The radionuclides⁵⁴Mn,⁶⁰Co,⁹⁰Sr,⁹⁵Nb,⁹⁵Zr,¹⁰³Ru,¹⁰⁶Ru,¹²⁵Sb,¹³¹I,¹³⁴Cs,¹³⁷Cs,¹⁴⁰Ba,¹⁴⁴Ce,²²⁶Ra and²²⁸Ac have been studied in the Sava River environment since the Chernobyl accident in 1986. The measured periphyton concentration ratios (CR) for each radionuclide were correlated with the measured sediment distribution coefficients (K_d) for that radionuclide. The K_d-CR relationships obtained were defined by the equation ln K_d=–0.5 ln CR +7.4. These K_d-CR relationships were assumed to be referable to the Sava River ecosystem and were used to predict the missing soil K_d values and/or the missing CR values for the wide range of radionuclides, respectively. Moreover, the K_d-CR relationship characteristic for the Sava River ecosystem was compared with the K_d-CR relationship proposed by Baes¹ and by Shepard². The characterization of the partition coefficients in the Sava River environment and understanding of the mechanisms affecting radionuclide retardation and bioaccumulation are required for the planning of radioactive waste depositories in the area.     

The development of a sampler-sensor using a vanadium-oxinate-polymer film for the selective and direct determination of atmospheric ethanol

The development of a sensor for the direct and selective determination of atmospheric ethanol is in the initial stages. The sensor takes advantage of the selective chemical reaction between ethanol and vanadium oxinate. This reaction occurs in an organic medium where a red colored complex is the product. This reaction is determined spectrophotometrically where the absorbance maxima is 475 nm. The focus of this paper is to discuss the parameters necessary to develop a solid sorbent sampling-sensor which can be used to determine atmospheric ethanol.