K5Nd(MoO4)4: a self-tunable laser crystal

We report for the first time to our knowledge an experimental demonstration of wavelength self-tuning in a K5Nd(MoO4)4 broadband-emitting laser crystal (KNM), as well as a theoretical treatment of the system based on its birefringence properties. The self-frequency-tuning of the laser along the full spectral range of the KNM crystal was obtained by rotating a birefringent gain plate in its own plane. The gain plate was placed inside a resonator at Brewster's angle. The tuning characteristics of the spectral filter were obtained by use of the Jones vector formalism. The calculated wavelength-selective tuning precisely matches the experimental observations.     

Spin on a 4D Feynman Checkerboard

We discretize the Weyl equation for a massless, spin-1/2 particle on a time-diagonal, hypercubic spacetime lattice with null faces. The amplitude for a step of right-handed chirality is proportional to the spin projection operator in the step direction, while for left-handed it is the orthogonal projector. Iteration yields a path integral for the retarded propagator, with matrix path amplitude proportional to the product of projection operators. This assigns the amplitude i ^±T 3^?B/2 2^?N to a path with N steps, B bends, and T right-handed minus left-handed bends, where the sign corresponds to the chirality. Fermion doubling does not occur in this discrete scheme. A Dirac mass m introduces the amplitude i ?? m to flip chirality in any given time step ??, and a Majorana mass similarly introduces a charge conjugation amplitude.     

Information Reconstruction on an Infinite Tree for a $$4\times 4$$ 4 × 4 -State Asymmetric Model with Community Effects

Journal of Statistical Physics - The reconstruction problem on an infinite tree, is to collect and analyze massive data samples at the nth level of the tree to identify whether there is...     

Effect of a Mo impurity on the luminescence properties of CdWO4, ZnWO4, and CaWO4

The thermoluminescence, the spectral composition of the x-ray luminescence and the thermoluminescence, the short-wave absorption, and the luminescence-excitation spectra were studied for ZnWO₄, CdWO₄, and CaWO₄ single crystals with and without molybdenum impurities. The thermal-activation energies were found for radiationless transitions for all these crystals from the temperature dependence of the steady-state x-ray luminescence. A qualitative explanation for the results is offered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 10, pp. 72–77, October, 1970.Deceased.     

The b 4Σ- → a 4Π band system of nitric oxide

The quartet emission spectrum b ⁴Σ^- → a ⁴Π of NO at 790 nm (Δv=4) has been rotationally analysed and molecular rotational constants for the two states obtained.     

Thermopower of a moderate heavy-fermion compound YbZnCu4

The thermopower coefficients S of samples of a moderate heavy-fermion compound YbZnCu₄ and metallic LuZnCu₄ are measured in the temperature range 5–300 K. Data on the temperature dependence of the thermopower coefficient S of YbZnCu₄ suggest that this material is a heavy-fermion compound with a Kondo temperature of ～50 K.     

Detection of modulation of a 4-kHz carrier

To better understand the processing of complex high-frequency sounds, modulation-detection thresholds were measured for sinusoidal frequency modulation (SFM), quasi-frequency modulation (QFM), sinusoidal amplitude modulation (SAM), and random-phase FM (RPFM). At the lowest modulation frequency (5 Hz) modulation thresholds expressed as AM depth were similar for RPFM, SAM and QFM suggesting the predominance of envelope cues. At the higher modulation frequencies (20 and 40 Hz) thresholds expressed as total frequency excursions were similar for SFM and QFM suggesting a common mechanism, one perhaps based on single-channel FM-to-AM conversion or on a multi-channel place mechanism. The fact that the nominal envelopes of SFM and QFM are different (SFM has a flat envelope), seems to preclude processing based on the envelope of the external stimulus. Also, given the 4-kHz carrier and the similarity to previously published results obtained with a 1-kHz carrier, processing based on temporally-coded fine structure for all four types of modulation appears unlikely.     

Characteristics of a 4-fold segmented clover detectore

Four high-purity germanium 4-fold segmented Clover detectors have been     

Passive control of a 4-scroll chaotic system

This paper studies the control of a new chaotic system which can generate 4-scroll attractors. Based on the properties of a passive system, it derives the essential conditions under which this new chaotic system could be equivalent to a passive system and globally asymptotically stabilize at a zero equilibrium point via smooth state feedback. Simulation results and circuit experiment show that the proposed chaos control method is effective.     

A 4-neutrino model with a Higgs triplet

We take as a starting point the Gelmini–Roncadelli model enlarged by a term with explicit lepton number violation in the Higgs potential and add a neutrino singlet field that is coupled via a scalar doublet to the usual leptons. This scenario allows us to take into account all three present indications in favor of neutrino oscillations provided by the solar, atmospheric, and LSND neutrino oscillation experiments. Furthermore, it suggests a model which reproduces naturally one of the two 4-neutrino mass spectra favored by the data. In this model, the solar neutrino problem is solved by large mixing MSW transitions, and the atmospheric neutrino problem by transitions of into a sterile neutrino. Received: 11 May 1999 / Published online: 3 February 2000     

FeSO_4 as a Novel Li-Ion Battery Cathode

FeSO_4 has the characteristics of low cost and theoretical high energy density(799 W·h·kg~(-1) with a two-electron reaction), which can meet the demand for next-generation lithium-ion batteries. Herein, FeSO_4 as a novel highperformance conversion-reaction type cathode is investigated. We use dopamine as a carbon coating source to increase its electronic conductivity. FeSO_4@C demonstrates a high reversible specific capacity(512 mA·h·g~(-1))and a superior cycling performance(482 mA·h·g~(-1) after 250 cycles). In addition, we further study its reaction mechanism. The FeSO_4 is converted to Fe and Li_2SO_4 during lithium ion insertion and the Fe—Li_2SO_4 grain boundaries further store additional lithium ions. Our findings are valuable in exploring other new conversion-type lithium ion battery cathodes.     

Characteristics of a 4-fold segmented clover detectore

Four high-purity germanium 4-fold segmented Clover detectors have been applied in the experiment of neutron-rich nucleus 21N. The performance of those four Clovers have been tested with radioactive sources and in-beam experiments, and the main results including energy resolution, peak-to-total ratios, the variation of the hit pattern distribution in different crystals of one Clover detector with the energy of γ ray, and absolute full energy peak detection effciency curve, were presented.     

Towards a microscopic theory of superfluid 4He

A generic Hamiltonian, which contains the potential energies and the coulomb interactions of an assembly of N ⁴He nuclei and 2N electrons is studied using second quantisation techniques and different sets of boundary conditions for three related problems. For an infinite volume of fluid periodic boundary conditions are imposed. For a finite volume which fills a cube the wave functions are chosen to vanish on the boundaries and for a finite volume contained in a vessel of arbitrary shape similar boundary conditions are imposed on a macroscopic volume of the liquid which is sufficiently remote from the walls and surface. In each example the appropriate value of N is determined by using the known density of the liquid. Use is also made of several other experimentally determined properties; that, at the lowest temperatures, the liquid is almost entirely super-fluid and that as the temperature is raised it appears to be composed of two homogeneously mixed fluids, the super- and the normal fluid, with little change in overall density. The first of these properties is used as a guide to a possible form for the ground state of an unperturbed Hamiltonian, that it should be a many-particle function that ensures that the density of particles and charge is uniform in space. The second is used to reason that each low-lying excited state of the unperturbed Hamiltonian will contain a part in which the ground state appears to have been expanded and the overall density has been restored by replacing the particles which have been removed in the expansion back into states which have not been used in forming the expanded ground state. A detailed examination of such a possibility shows that there are many possible ways of constructing mutually orthogonal states with this property. So the way is open to using these states as basis states for a perturbation theory and characterising them with a momentum variable, k. Another property, that the super-fluid supports longitudinal phonon-like modes is then used to define some more low-lying states, so enlarging the number of mutually orthogonal many-particle states. It is then a relatively simple exercise in perturbation theory to show how, after the meaning of the momentum variable, k, has been slightly changed, the famous (, k) dispersion curve emerges.     

Creating a monopole in 4D gauge theories

The problem of defining the second quantized monopole creation operator in non-Abelian gauge theories is discussed and exemplified by the (3 + 1)-dimensional Georgi-Glashow model. We construct the “coherent state” operator M(x) that creates the Coulomb magnetic field in terms of the Dirac singular electromagnetic potential. Our calculation of the vacuum expectation value of this operator 〈M(x)〉 in the confining phase indicates that it is free from the singularity along the Dirac string and in the leading order of perturbation theory the 〈M(x)〉 vanishes as a power of the volume of the system. This supports the conception that inclusion of the nonperturbative effects introduces an effective infrared cutoff on the calculation providing the finiteness of vacuum expectation value 〈M(x)〉. The text was submitted by the authors in English.