Quantization: Deformation and/or Functor?

After a short presentation of the difference in motivation between the Berezin and deformation quantization approaches, we start with a reminder of Berezin’s view of quantization as a functor followed by a brief overview of deformation quantization in contrast with the latter. We end by a short survey of two main avatars of deformation quantization, quantum groups and quantum spaces (especially noncommutative geometry) presented in that perspective.     

Anticonformity or Independence?—Insights from Statistical Physics

The aim of this paper is to examine how different types of social influence, introduced on the microscopic (individual) level, manifest on the macroscopic level, i.e. in the society. The inspiration for this task came mainly from two sources—social psychology that recognize two different types of nonconformity (anticonformity and independence) and the observation related to the agent-based modeling that was verbalized in 2002 by Macy and Willer that there was a little effort to provide analysis of how results differ depending on the model designs. To achieve the goal, we propose a generalized model of opinion dynamics, that as a special cases reduces to the linear voter model, Sznajd model, q-voter model and the majority rule. We use the model to examine the differences, that appear at the macroscopic level, under the influence of two types of nonconformity, introduced on the microscopic level. We answer the question if the observed differences are universal or model dependent.     

Charm in PHENIX—a signal or a background?

Charm, as well as Strangeness, plays an important role in searches for the Quark Gluon Plasma.J/Φ Suppression and Strangeness Enhancement are two of the earliest proposed QGP signatures. Recent theoretical work on charm in Relativistic Heavy Ion collisions has focussed on di-lepton production. However, even before the discovery of theJ/Ψ, evidence of open charm was seen in hadron collisions via the observation of promptsingle leptons “resulting from the semi-leptonic decays of charm particles.” [1] The ‘copious’ yield of direct (i.e. not from Dalitz decays) single electrons and muons—at a levele/π～10^?4 forpT≥1.3 GeV/c—observed in the early 1970’s was explained by Hinchliffe and Llewellyn-Smith and Bourquin and Gaillard as evidence of open-charm production. It is likely thate/π at RHIC is large and is a good measure of charm production. Thus, a measurement of single electrons with moderatepT>1.5 GeV/c at RHIC should give a clean charm signal in heavy ion collisions,with no combinatoric background.     

Hexagonal close-packed nickel or Ni3C?

I compare the lattice spacings, synthesis conditions, and magnetic properties of hexagonal close-packed (hcp) Ni with Ni₃C reported recently in the literature. The reported lattice spacings and synthesis conditions of hcp Ni and Ni₃C are almost indiscernible. In addition, the magnetic properties of hcp Ni and Ni₃C show similar characteristics. Based on my experimental investigations on Ni₃C and the reported density functional theory calculations on the magnetic properties of hcp Ni, I present an explanation for understanding the discrepancies in the experimental results regarding hcp Ni reported in the literature.     

The structure of solid salt eutectics — – Why lamellar or conglomerate?

Using KCl/ZnSO₄ eutectic it has been shown that cooling the melt into a room temperature enclosure forms a lamellar structure, whereas cooling into a heated enclosure (225 °C) forms a conglomerate structure, while an enclosure temperature of 125 °C gave a partially conglomerate structure with some lamellae in process of forming conglomerates.Consideration of the thermal gradients imposed on solidification and consequently the relative time available during which the ions are sufficiently mobile to rearrange their positions, can explain the observation that lamellar structures are formed by higher melting point eutectics, whereas eutectics of lower melting point form conglomerate structures.     

Single or both site doped BiFeO3—Which is better candidate for profound electronic device applications?

Magnesium (Mg) and Zirconium (Zr) doped bismuth ferrite (BiFeO₃; BFO) such as Bi_1?xMg_xFeO₃ (Mg doped BFO; BMO), BiFe_1?xZr_xO₃ (Zr doped BFO; BZO) and Bi_1?xMg_xFe_1?xZr_xO₃ (both Mg and Zr doped BFO; BMZO) were synthesized by solid-state reaction techniques with dopant concentrations x?=?0 and 0.1, respectively. The distorted rhombohedral structures of doped BFO were confirmed by X-ray diffraction analysis. The microstructural analysis revealed that there were uniform dispersions and homogeneous distributions of ceramics in BMZO as compared to BMO, BZO and pure BFO. The presence of both grain and grain boundary in BMZO indicated its good electrical response than others as evidenced from impedance analysis and in agreement with AC conductivity study. The dielectric and ferroelectric measurement signified that BMZO possessed enhanced dielectric constant and high remanent polarization thus could be a better prominent candidate than others to be used in electronic devices.     

Lasers without photons — or should it be lasers with too many photons?

Expanding the fields of a laser cavity in a set of orthonormal modes is a standard technique in laser theory. Expansion in a normal mode set is also the basis of the concept of photons. A substantial number of practical lasers do not, however, support any kind of normal or orthogonal cavity modes, and thus, their fields cannot be represented (at least not easily) in terms of normal modes, or photons. This leads to a number of unusual results, including situations in which the lowest-order mode of a cavity can contain substantially more energy than the total energy in the cavity, as well as enhanced quantum spontaneous emission far stronger than the single extra photon level characteristic of an ordinary laser oscillator. We review the theoretical origins of these unusual effects and present experimental confirmation of greatly enhanced Schawlow-Townes fluctuations in an unstable-resonator laser with a Petermann-noise enhancement factor of several hundred times.Dedicated to H. Walther on the occasion on his 60th birthday     

Cs/GaAs(100) surface: Two-dimensional metal or Hubbard insulator?

The evolution of the characteristic electron energy loss spectra accompanying the deposition of cesium on GaAs(100) surfaces with various superstructural reconstructions is studied experimentally. It is shown that the appearance of loss peaks in the GaAs band gap for Cs coverages θ_Cs>0.5 monolayers is due to resonances in the longitudinal and transverse polarizability of two-dimensional metallic clusters of adatoms. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 8, 537–542 (25 October 1999)     

Anomalous fluoride concentration in groundwater—is it natural or pollution? A stable isotope approach

Fluoride anomalies (up to 11 mg/l) have been detected in groundwater of the central region of Rio Grande do Sul State, Southern Brazil, in an area where fluorosis is endemic. Two hypotheses are investigated concerning the fluoride origin: lithochemical affiliation from regional rock or contamination by fertilisers application. These hypotheses are discussed based on the stable isotope data of water, nitrate, and sulphate, which indicates that the local precipitation is the main groundwater recharge source. The isotopic composition of groundwater sulphate is similar to that of fertiliser sulphate. However, a conclusive assignment of groundwater sulphate to fertiliser origin is not indicated because further possible sulphate sources fall into the same isotopic range. In contrast, the isotopic composition of dissolved nitrate suggests that there is no direct relationship to the use of NPK fertilisers. Hence, an origin of the high fluoride content in groundwater related to long-term rock–water interactions seems likely.     

Triviality—Quantum Decoherence of Fermionic Quantum Chromodynamics SU(Nc) in?the?Presence of?an?External Strong U(∞) Flavored Constant Noise Field

We consider the problem of infrared divergencies in String theory in Embeddings Manifolds by means of the Nash Theorem of Riemann metrics parametrized by immersions.     

Effect of high pressure and chemical substitution on the crystal structure and magnetic state of R2Fe17 ? xSix (R = Lu or Y; x = 0 or 1.7)

The effect of high pressure on the crystal structure of the intermetallic compounds R₂Fe_{17 − x} Si_x (R = Lu or Y; x = 0 or 1.7) was studied using neutron diffraction. A correlation between changes in structural parameters and magnetic properties under the action of high pressure, as well as under chemical substitution of Si for Fe atoms, was analyzed in terms of localized moment and spin fluctuation models. The spin fluctuation model was found to describe more adequately the experimentally observed increase in the Curie temperature upon chemical substitution and the decrease in this temperature under the action of high pressure. Possible reasons for the suppression of a collinear ferromagnetic state and the occurrence of a noncollinear antiferromagnetic state in R₂Fe_17−x Si_x under pressure are discussed based on estimated differences between the total energy minima of these states.     

Can potentially useful dynamics to solve complex problems emerge from constrained chaos and/or chaotic itinerancy?

Complex dynamics including chaos in systems with large but finite degrees of freedom are considered from the viewpoint that they would play important roles in complex functioning and controlling of biological systems including the brain, also in complex structure formations in nature. As an example of them, the computer experiments of complex dynamics occurring in a recurrent neural network model are shown. Instabilities, itinerancies, or localization in state space are investigated by means of numerical analysis, for instance by calculating correlation functions between neurons, basin visiting measures of chaotic dynamics, etc. As an example of functional experiments with use of such complex dynamics, we show the results of executing a memory search task which is set in a typical ill-posed context. We call such useful dynamics "constrained chaos," which might be called "chaotic itinerancy" as well. These results indicate that constrained chaos could be potentially useful in complex functioning and controlling for systems with large but finite degrees of freedom typically observed in biological systems and may be such that working in a delicate balance between converging dynamics and diverging dynamics in high dimensional state space depending on given situation, environment and context to be controlled or to be processed.     

New nonlinear optical crystals of the M1 ? xSc3 ? yYx + y(BO3)4 (M = Ce, Pr, or Nd) family

New Y_0.57M_0.72Sc_2.71(BO₃)₄ (M = Pr or Nd) nonlinear optical crystals of the huntite structural type with sp. gr. R32 were grown by the high-temperature solution-melt method. The analogous phase with cerium was prepared by solid-state synthesis. Lattice parameters were established by X-ray diffraction patterns of the powder.     

Surface segregation during the uptake of NO3 on coatings composed of NaI · 2H2O/NaBr · 2H2O and MgBr2 · 6H2O/MgCl2 · 6H2O binary salts: Solubility or deliquescence?

The uptake of NO₃ radicals on the surface of coatings prepared from the individual salts of NaI and NaBr dehydrates, hexahydrates of MgBr₂, and MgCl₂ and NaI · 2H₂O/NaBr · 2H₂O and MgBr₂ · 6H₂O/MgCl₂ · 6H₂O binary salts at various mole fractions of the doping salts, NaI · 2H₂O and MgBr₂ · 6H₂O in the initial aqueous solution was measured in a flow reactor by kinetic mass spectrometry. The dependences of the rates of the consumption of the reactant and of the formation of the products on the mole fraction of the doping salt made it possible to determine a quantitative relationship between the surface density of the doping salt and its mole fraction in the initial solution. A joint analysis of these dependences and the previously obtained data led to the conclusion that the deliquescence of the studied individual salts produces the predominant effect on the ratio between their surface densities.