Topological voiceprints for speaker identification

Despite its noninvasive nature, subject identification by voice is not as popular as other biometric procedures (i.e. fingerprinting). In part, this is due to the difficulty of establishing how close is close enough when comparing spectral features. In this work, we address this issue by showing how to characterize spectra by means of sets of integers, borrowing topological tools used in the theory of dynamical systems. On the other hand, we report an empirical result: within a relatively small bank of speakers, there are subsets of integers that seem to strenghten the speakers’ identity information. These results suggest a new direction in the identification of subjects by voice: one in which arrangements of integers define voiceprints that stand on their own, despite any acceptance/rejection thresholds.     

Peculiar acceleration

It has been proposed recently to observe the change in cosmological redshift of distant galaxies or quasars with the next generation of large telescope and ultra-stable spectrographs (the so-called Sandage–Loeb test). Here we investigate the possibility of observing the change in peculiar velocity in nearby clusters and galaxies. This “peculiar acceleration” could help reconstructing the gravitational potential without assuming virialization. We show that the expected effect is of the same order of magnitude of the cosmological velocity shift. Finally, we discuss how to convert the theoretical predictions into quantities directly related to observations.     

Peculiar scaling of self-avoiding walk contacts

The nearest neighbor contacts between the two halves of an N-site lattice self-avoiding walk offer an unusual example of scaling random geometry: for N-->infinity they are strictly finite in number but their radius of gyration R(c) is power law distributed proportional to R(-tau)(c), where tau>1 is a novel exponent characterizing universal behavior. A continuum of diverging length scales is associated with the R(c) distribution. A possibly superuniversal tau = 2 is also expected for the contacts of a self-avoiding or random walk with a confining wall.     

Peculiar lunar echoes at 13.866 MHz

Summary Peculiar lunar echoes obtained with a radar operating at 13.866 MHz are presented and discussed. Some of their features are reconduced to a total or to a partial guidance by ionospheric and magnetospheric irregularities aligned with the geomagnetic lines of force. Precisely, such irregularities are intervening as natural wave guides or as leaky-wave antennas. In the latter case they are characterized by very high gains so that one can speak of a sort of focusing. This focusing could be used for the observation of magnetospheric turbulence, could explain some of the solar bursts and could suggest a practical utilization of the round-the-world propagation.

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Riassunto Insoliti echi lunari ottenuti con un radar operante su una frequenza di 13.866 MHz sono presentati e discussi. Alcune loro caratteristiche sono ricollegate a una totale oppure a una parziale azione di guida da parte di irregolarità ionosferiche e magnetosferiche allineate con le linee di forza del campo geomagnetico. Precisamente dette irregolarità intervengono in qualità di guide d’onda naturali o di antenne a perdita d’onda. Queste ultime sono caratterizzate da altissimi guadagni, così che si può in un certo senso parlare di focalizzazione. Questa focalizzazione potrebbe essere usata per l’osservazione della turbolenza magnetosferica, potrebbe spiegare alcuni degli scoppi solari (solar bursts) e potrebbe suggerire una pratica utilizzazione della propagazione orbitale.

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Резюме Анализируется характерное лунное эхо, полученное с помощью радара, действующего на частоте 13.866 Мгц. Некоторые из особенностей эхо предопределяют ионосферные и магнитосферные иррегулярности, ориентированные вдоль геомагнитных силовых линий. Такие иррегулярности мешают распространению волн. Иррегулярности характеризуются очень большими усилениями, так что можно говорить о некотором виде фокусировки. Эта фокусировка может быть использована для наблюдения магнитосферической турбулентности, может объяснить некоторые солнечные вспышки и может служить для практического использования при распространении вокруг земного шара.

     

Peculiar features of the deuteron scattering potential

Measurements at 52 MeV of elastic scattering of polarized deuterons including the nuclear rainbow region are analyzed “model independently” to yield the underlying scattering potential. The extracted potentials are surprisingly well determined in the nuclear interior. The radial shape of the real parts is found to coincide closely with that observed in nucleon scattering — in contrast to the folding picture, which, however, accounts well for the volume integral of the absorption.     

Peculiar aspects of galvonamagnetic properties of InS single crystals

The electrical conductivity and the Hall effect in electronic InS single crystals have been studied over a wide range of temperatures, from 150 K to 800 K, and their peculiarities have been elucidated. At temperatures of 200 K the Hall coefficient passes through a maximum but does not reach a minimum. The peculiarities of the temperature dependence of the Hall coefficient are explained within the two-band model, which incorporates the conduction band and the impurity band. The parameters of the impurity band have been determined. The hopping mechanism of scattering has been found to predominate in InS single crystals in the temperature range 150–270 K, and at temperatures of 270 K to 400 K the mobility is limited, mainly by scattering on impurity ions. Above 400 K electrons are scattered on polar lattice vibrations.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 29–34, January, 1989.     

Peculiar magnetic aftereffect of highly diluted frozen magnetic fluids

A very stably dispersed magnetic fluid (mother MF) and its 1000-times diluted solution were independently zero-field-cooled from room temperature to 5 K followed by application of a magnetic field of 2.86 MA/m for 300 s. After the field was removed (t=0)$(t=0)$, its residual magnetization M was measured as a function of time t for 80 000 s. After measurement, the MF sample was heated to room temperature, and the experiment was repeated after cooling to 5 K and again applying and removing the 2.86 MA/m field. We performed the same experiment several times, and obtained a different M vs t curve each time. With each cycle, the average M increased and the M vs t curve converged to a universal curve. In the initial few cycles, the value of M is very small, fluctuates and surprisingly increases with t in some time region. These characteristics are common in both the mother MF and diluted MF. We consequently propose the following physical model. When the MF is cooled, the isolated surfactant molecules in the solvent trigger the generation of magnetic colloid micelles. In other words, there occurs a phase transition from the magnetic colloids’ monodispersed phase to a micelle phase. The magnetic dipoles of the micelle's colloids make a closed magnetic flux loop. That is the origin of the anomalously small value of the residual magnetization in the early cycles. After a certain time elapses the micelles spontaneously break due to their residual stress, and a finite magnetic moment of the individual micelle develops. Consequently, M increases with t during this period.     

Peculiar Features of Plasma-Focus Discharges Within PF-360 Facility

The paper reports on recent studies of plasma-focus (PF) discharge dynamics and fusion neutron emission, which were performed with the PF-360 device at the energy level of about 120 kJ and the maximum current of 1.85 MA. Using the high-speed multi-frame imaging system, the behavior of a current-sheath layer during the radial compression phase and of a plasma column during the pinch phase has been investigated. Dynamics of the pinch phase was studied in the visible radiation and soft X-rays simultaneously. Characteristics of the neutron emission from PF discharges, which were carried out with and without the use of planar D₂O-ice target, were studied experimentally. In particular, the anisotropy coefficient, defined as a ratio of the fusion-neutron yield to that measured at 90° to the z-axis, i.e. Y _n()/Y _n (90°), was investigated under different experimental conditions. Various structures of the time-resolved neutron signals were recorded and interpreted, e.g. as a result of a double pinch. Possible mechanisms of the fusion neutron production have also been discussed.     

Peculiar effects of anisotropic diffusion on dynamics of vicinal surfaces

We report on peculiar behaviors due to anisotropic terrace diffusion on step meandering on a vicinal surface. We find that anisotropy triggers tilted ripples. In addition, if the fast diffusion direction is perpendicular to the steps, the instability is moderate and coarsening is absent, while in the opposite case the instability is promoted, and interrupted coarsening may be observed. Strong enough anisotropy restabilizes the step for almost all step orientations. These findings point to the nontrivial effect of anisotropy and open promising lines of inquiries in the design of surface architectures.     

Peculiar features of heat capacity for Cu and Ni nanoclusters

The heat capacity of copper and nickel clusters (from 2 to 6 nm in diameter) was investigated in the temperature range 200–800 K using molecular dynamics method and a modified tight-binding potential. The simulation results demonstrate a very good agreement with the available experimental data at T = 200 K and a fairy good agreement at higher temperatures. A number of regular trends are revealed in computer experiments which agree with the corresponding theoretical predictions. A conclusion is made that in the case of single free clusters the heat capacity may exceed the capacity of the corresponding bulk material. It is found that at 200 K, the copper nanocluster (D = 6 nm) heat capacity is higher by 10% and for nickel cluster by 13%. The difference diminishes with increasing the nanoparticles size proportionally to the relative number of surface atoms. A conclusion is made that very high values of the nanostructure heat capacity observed in laboratory experiments should not be attributed to free clusters, i.e., the effect in question is caused by other reasons.     

Peculiar relics from Primordial Black Holes in the inflationary paradigm

Depending on various assumptions on the energy scale of inflation and assuming a primordial power spectrum of a step‐like structure, we explore new possibilities for Primordial Black Holes (PBH) and Planck relics to contribute substantially to Cold Dark Matter in the Universe. A recently proposed possibility to produce Planck relics in four‐dimensional string gravity is considered in this framework. Possible experimental detection of PBHs through gravitational waves is also explored. We stress that inflation with a low energy scale, and also possibly when Planck relics are produced, leads unavoidably to relics originating from PBHs that are not effectively classical during their formation, rendering the usual formalism inadequate for them.     

Peculiar Quantum Phase Transitions and Hidden Supersymmetry in a Lipkin-Meshkov-Glick Model

In this paper we theoretically report an unconventional quantum phase transition of a simple Lipkin- Meshkow-Glick model： an interacting collective spin system without external magnetic field. It is shown that this model with integer-spin can exhibit a flrst-order quantum phase transition between different disordered phases, and more intriguingly, possesses a hidden supersymmetry at the critical point. However, for half-integer spin we predict another flrst-order quantum phase transition between two different long-range-ordered phases with a vanishing energy gap, which is induced by the destructive topological quantum interference between the intanton and anti-instanton tunneling paths and accompanies spontaneously breaking of supersymmetry at the same critical point. We also show that, when the total spin-value varies from half-integer to integer this model can exhibit an abrupt variation of Berry phase from π to zero.     

Peculiar transmission property of acoustic waves in a one-dimensional layered phononic crystal

In this article, we report both theoretical calculation and experimental observation of acoustic waves abnormally through a one-dimensional layered transmitted phononic crystal at frequencies within the band gap into a material of large acoustic impedance mismatch, with an efficiency as high as unity. The transmission peaks can be interpreted as a result of the interference of acoustic waves reflected from all periodically aligned interfaces. The condition for the appearance of peaks is analyzed in detail and the optimized layer number is given for different configurations.     

Peculiar meaning of the concept of the information depth in appearance potential spectroscopy

The information depth of APS is not related to the escape depth of the Auger electrons, because all electrons escaping from the target at a threshold potential can contribute to the signal without respect to the amount of energy they have lost. Nevertheless, the definition of the information depth proposed by the E-42 Committee of the American Society for Testing and Materials is still valid. Our paper presents and discusses results of a recent experimental investigation of the information depth of AEAPS and DAPS.     

Peculiar statistical properties of Chinese stock indices in bull and bear market phases

Chinese stock markets have experienced an extraordinary bull market since Jan 2006, which attracted global eyes. We investigate the statistical properties of the indices’ log-return r(t) for the bull market (Jan 2006-Oct 2007) and the previous bear market (Jan 2001-Dec 2005). Here we report three peculiar features of r(t): (i) the cumulative distribution function curve of r(t) in the bull market is similar to that in the bear market; (ii) the autocorrelation function of r(t) in the bull market has a stronger negative correlation and a shorter correlation time than that in the bear market; (iii) the bull market shows stronger long-term correlation than the bear market. This work has relevance to understanding novel statistical properties in economic systems.     

Peculiar features of the interaction potential between hydrogen and antihydrogen at intermediate separations

This paper evaluates the interaction potential between a hydrogen and an antihydrogen using the second-order perturbation theory within the framework of the four-body system in a separable two-body basis. It finds that the H-H interaction potential possesses the peculiar features of a shallow local minimum located around interatomic separations of r ～ 6a.u. and a barrier rising at τ ≤5a.u.