Quality and loudness judgments for music subjected to compression limiting

Dynamic-range compression (DRC) is used in the music industry to maximize loudness. The amount of compression applied to commercial recordings has increased over time due to a motivating perspective that louder music is always preferred. In contrast to this viewpoint, artists and consumers have argued that using large amounts of DRC negatively affects the quality of music. However, little research evidence has supported the claims of either position. The present study investigated how DRC affects the perceived loudness and sound quality of recorded music. Rock and classical music samples were peak-normalized and then processed using different amounts of DRC. Normal-hearing listeners rated the processed and unprocessed samples on overall loudness, dynamic range, pleasantness, and preference, using a scaled paired-comparison procedure in two conditions: un-equalized, in which the loudness of the music samples varied, and loudness-equalized, in which loudness differences were minimized. Results indicated that a small amount of compression was preferred in the un-equalized condition, but the highest levels of compression were generally detrimental to quality, whether loudness was equalized or varied. These findings are contrary to the "louder is better" mentality in the music industry and suggest that more conservative use of DRC may be preferred for commercial music.     

Double-hole binding energy shifts for the 5d transition metals

Recent experimental M₄₅N₆₇N₆₇ Auger energies for Ta, W, Ir, Pt, Au, Hg and Pb are analyzed in terms of the complete screening picture. For the shift in the double-hole (N₆₇N₆₇) binding energy between the free atom and the metal a good agreement is found between theory and experiment. The variation of the shift throughout the 5d series and beyond reflects different types of screening of the two core holes, i.e. a large shift in the case of d-type screening and a considerably smaller shift for sp-type screening.     

The effective activation energy Ueff(T,B,J) in Hg-1223 single phase superconductors

We review the methods of calculating the effective activation energy U_eff(T,B,J) for both transport measurements and magnetic decay, together with some theoretical models. Then, we apply these methods to our Hg-1223 single-phase superconductor to obtain the activation energy. Transport results give that the magnetic field and temperature dependence of the U_eff can be well described as U₀B^−α(1−T/T_c)^m. Magnetic relaxation shows that the current density dependence of U(J) can be scaled onto a single curve, which can be considered as the activation energy at some temperature T₀. The pinning mechanism in the measured temperature range does not change, and the activation energy depends separately on the three variables: T, B, and J, are responsible for the magnetic decay data scaling onto a single curve at various temperatures. As temperatures close to zero and near T_c, thermally assisted flux motion model is no longer valid since other processes dominate.     

The loss of single vacancies in metals during quenching

The Lomer equation, describing the rate of change of single vacancy concentration in a metal specimen during exponential quenching, was numerically solved for different quenching temperatures and different quenching rates. A relation has been found between the constantb, which characterizes the initial quenching rate, and the quenching temperature leading to the same percentual loss of vacancies. This relation enables us to determine the conditions of quenching, yielding the predetermined percentage of retained vacancies.The possibility is discussed of applying the above results in measurements of the formation energyEf^F, to estimate the migration energyE ^M and to determine the change of the mean number of jumps during quenching.The author would like to express his gratitude to Dr. K. Míek, head of the Metal Physics Department, for his interest and useful comments.     

Hc2-Anisotropy in TaN single crystals

Experiments on the anisotropy of H_c2 in a tantalum single crystal doped with nitrogen in order to change its behaviour from type-I to type-II superconductivity are reported. The results show a disappearance of the anisotropy coefficient a₆ and are compared to the anisotropy in niobium single crystals.     

Correlation effects in the photoelectron spectra of 3d metals

An approximate method is presented for calculation of the orbital relaxation in photoelectron spectra for systems with a continuous distribution of electron states. The results for Fe, Ni and Cu 3d states explain the discrepancy between experimental data and band structure calculations. The nature of the satellite in photoelectron spectra of Ni is discussed.     

Anisotropy of positron wave function in 4d transition metals

The positron wave functions have been calculated employing the method of expansion of symmetrized plane waves in some 4d transition metals. Systematics of the positron wave functions along the three symmetry directions [100], [110], [111] in these metals, have been discussed. The anisotropies of the ψ₊ have been found to be strongly dependent upon the crystal symmetries. The results of the band structure calculation of 2γ-angular correlation in Rh and Ag are presented.     

Formation of compression shocks in a nonequilibrium plasma flow in a magnetic field

Plasma flow in a linearly widening, ideally sectioned, short-circuited magnetohydrodynamic (MHD) channel is studied. MHD flows are classified into two types: continuous flows and flows with a compressional MHD shock in plasmas that are stable and unstable against the onset of ionization instability. Specific features in the evolution of a stationary compression MHD shock are investigated, and its position as a function of the Stewart number is determined. It is found that, in a plasma flow in which ionization instability develops, a compression MHD shock arises at lower values of the MHD interaction parameter than in a stable plasma flow. An unidentified type of instability of MHD discontinuities is revealed.     

Negative magnetoresistance in (SN)x single crystal

The magnetoresistance in (SN)x single crystals is composed of the normal positive and negative components. The former increases in proportion to the square of the magnetic field B². The latter is remarkable at temperatures below 4.2 K and saturates at relatively low magnetic field (? 30 kG). The coefficient $\text{S(=}\text{lim}\text{B→0}\text{{??}\text{(}\text{δρ}\text{ρ}{}_0\text{)}\text{?B}{}^2\text{})}$ of this negative magnetoresitance shows features similar to those of semiconductors with Toyozawa's theory. These results of negative magnetoresistance are explained in terms of carrier scattering by localized magnetic moments.     

A promising guanidinium based metal-organic single crystal for optical power limiting applications

A novel guanidinium based metal-organic framework material [(2(C H₆ N₃)⁺.Zn (C₂H₃O₂)₄]− has been synthesized and optical transparency of the crystals was studied. Structural parameters of the grown metal-organic crystals have been characterized by single crystal X-ray diffraction. The single crystal XRD study confirms that the title compound crystallized in tetragonal system with I 4₁ /a c d space group. The crystal structure has stabilized through intricate 3-D hydrogen bonding network established by the NH…O and CH…O interactions. The soft nature of the material has been identified by hardness study. UV–visible spectroscopy has been used to investigate the optical properties. Good thermal stability has been proved by TG-DTA. The third order nonlinear optical response was studied by Z-Scan technique.     

Simulation of single slip in FCC metals

The study of single slip was performed by imitation simulation and mathematical simulation methods. In a modified barrier model of constant linear tension, all stages of the process of nucleation and propagation of single crystallographic slip to the field of discrete dislocation obstacles have been simulated and investigated. The equation of dynamics of expansion of an isolated closed planar dislocation loop, which restricts slipping, was used to perform a comparative study of the effect of the mechanisms of resistance to dislocation motion on the characteristics of the resulting single slip. Micromechanical characteristics of each dislocation loop emitted by a dislocation source after loss of stability have been calculated. The time it takes for single slip to propagate up to the barrier configurations that restrict slipping and the total formative time of the crystallographic shear zone have been estimated. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 57–68, January, 2006.     

Hyperfine interactions in intermetallic compounds between Gd and 3d transition metals

Measurements of hyperfine interactions at ¹⁵⁵Gd nuclei in metallic compounds between Gd and 3d transition metals and at ⁶¹Ni in GdNi compounds by Mössbauer spectroscopy are reported. The results are discussed in terms of various models proposed for the electronic structure of these compounds. The Gd isomer shifts with respect to metallic Gd are at variance with the model of a strong d electron transfer from rare earths to transition metal ions. From the observation of a linear relation between magnetic hyperfine fields at Gd and at Dy nuclei in corresponding compounds it is inferred that crystal-field induced variations of Dy moments are neglible and that the conduction electron polarization induced by 4f moments is directly related to that caused by 3d moments.     

N Law for bosons in 2D

A rigorous upper bound is derived for the exact ground-state energy of N negative charged bosons and N motionless, i.e. fixed, positive charges with Coulomb interactions in 2D for arbitrary N ? 4 giving rise to an N²-upper bound. The consistency of such an N² behaviour is also investigated by examining a lower bound to the ground-state energy.     

The inverse problem for a general N × N spectral equation

The spectral transform ?u/?x = {A(ζ)+B(x,ζ)} · u, where u is an n-element column vector and A(ζ) and B(x,ζ) are nxn matrices, is considered. A set of spectral data is given and the problem of reconcstructing B(x, ζ) from this spectral data is solved for a large class of cases. A special case of this spectral transform is used to solve the Boussinesq equation.     

The effects of the N atom collective Lamb shift on single photon superradiance

The problem of single photon collective spontaneous emission, a.k.a. superradiance, from N atoms prepared by a single photon pulse of wave vector k₀ has been the subject of recent interest. It has been shown that a single photon absorbed uniformly by the N atoms will be followed by spontaneous emission in the same direction [M. Scully, E. Fry, C.H.R. Ooi, K. Wodkiewicz, Phys. Rev. Lett. 96 (2006) 010501; M. Scully, Laser Phys. 17 (2007) 635]; and in extensions of this work we have found a new kind of cavity QED in which the atomic cloud acts as a cavity containing the photon [A.A. Svidzinsky, J.T. Chang, M.O. Scully, Phys. Rev. Lett. 100 (2008) 160504]. In most of our studies, we have neglected virtual photon (“Lamb shift”) contributions. However, in a recent interesting paper, Friedberg and Mannassah [R. Friedberg, J.T. Manassah, Phys. Lett. A 372 (2008) 2514] study the effect of virtual photons investigating ways in which such effects can modify the time dependence and angular distributions of collective single photon emission. In the present Letter, we show that such virtual transitions play no essential role in our problem. The conclusions of [M. Scully, E. Fry, C.H.R. Ooi, K. Wodkiewicz, Phys. Rev. Lett. 96 (2006) 010501; M. Scully, Laser Phys. 17 (2007) 635; A.A. Svidzinsky, J.T. Chang, M.O. Scully, Phys. Rev. Lett. 100 (2008) 160504] stand as published. However, the N atom Lamb shift is an interesting problem in its own right and we here extend previous work both analytically and numerically.     

Production of direct single electrons in proton-nucleus collisions at 13 GeV/c

Direct production of single electrons in proton-nucleus collisions at 13 GeV/c has been measured. A rising $\text{e}\text{π}$ ratio with decreasing p_T above the 10^?4 level is observed for low p_T single electrons. The source of the rising $\text{e}\text{π}$ ratio at low $\text{e}\text{π}$ ratio at low p_T is discussed in connection with the low mass dielectron continuum below the ? mass region.     

Two theorems on compression and self similar motion of coalesced shocks in a spherical implosion

A generalization of Guderley's result for compression in a coalesced sequence of n strong shocks is presented. It is also shown that in coalesced sequences comprising a large number of weak shocks and a small number of strong shocks the last component determines the parameters of the self-similar motion.     

Influence of anisotropic fluctuations on the electrical resistivity in uniaxial ferromagnetic metals near Tc

The generalized Ornstein-Zernike correlation function appropriate to a uniaxial ferromagnet is applied to study the influence of anisotropic fluctuations on the electrical resistivity in uniaxial ferromagnetic metals near T_c. It is shown that both the anisotropic fluctuations and the Fermi surface anisotropy contribute on the same footing to an anisotropy of the spin-fluctuation resistivity. The results are consistent with those obtained for the isotropic system in the same approximation and may be useful for interpreting recent spin-fluctuation resistivity data obtained experimentally for uniaxial systems.     

Evidence for correlation effects: −√T behaviour in the low temperature electrical resistance of disordered metals

It is found that the electrical resistance for several metal-metalloid amorphous alloys decreases with increasing temperature as ?√T from about 20 mK to several K. The form and magnitude of this temperature dependence is in agreement with recent predictions from interaction theories.