Semiclassical states for quantum cosmology

In a metric variable based Hamiltonian quantization, we give a prescription for constructing semiclassical matter-geometry states for homogeneous and isotropic cosmological models. These "collective" states arise as infinite linear combinations of fundamental excitations in an unconventional "polymer" quantization. They satisfy a number of properties characteristic of semiclassicality, such as peaking on classical phase space configurations. We describe how these states can be used to determine quantum corrections to the classical evolution equations, and to compute the initial state of the universe by a backward time evolution.Comment: 13 page

Checklist, distribution and bibliography of Mongolian Siphonaptera

Flea fauna in Mongolia is relatively unknown though the publications dealing with this problem are not few. The p·apers until 1966 are concerning ma.inly the territories delimited by natural plagua focis. Only in later periods, simu ltaneously with the intensive zoological research of the whole territory of the Mongolian People\u27s Republic, the more detailed research of flea fauna on the whole territory takes place. The systematic research began thanks to the Mongolian-German and MongolianHungarian expeditions, the members of which have collected considerable parasitological material covering the part of northern, eastern and western Mongolia. Since the year 1970 the Soviet-Mongolian academic expedition has been working on the territory of the Mongolian People\u27s Republic, as well as the Complex Chubsugul Mongolian-Soviet expedition, in which the members of the Comenius University in Bratislava have been working since the year 1974. On the basis of our own collections and the collections obtained from the Soviet-Mongolian academic expedition, from the Mongolian-German expedition, from the chair of Zoology Mongolian State University, from the Academy of science in Ulaan Baatar, and on the basis of literary data, on the territory of Mongolia there were recorded 157 species and subspecies of fleas. In future, many data (published) on the basis of single findings must be verified on some more materials from the viewpoint of progress in taxonomy in this group. There are concerned some species with cosmopolitan distribution (Xenopsylla cheopis, Ctenocephalides felis, Neopsylla teratura teratura, Rhadinopsylla li li, R. li ventricosa, subspecies Malaraeus penicilliger, Frontopsylla elata, Frontopsylla frontalis dubiosa, Citellophilus tesquorum mongolicus). The checklist contains: the sequence number of the taxon, the name of the taxon, the list of the publications mentioning the species in question. The publications are numbered as in the bibliography. Later, the localities are alleged, where the ajmaks are marked by the Roman figures and the localities in different ajmaks a.re marked by the Arabian figures. The division of ajmak and the localities are alleged on the map No. 1. The names of the localities are original Mongolian with the transcription into English

Solving the Problem of Time in Mini-superspace: Measurement of Dirac Observables

One solution to the so-called problem of time is to construct certain Dirac observables, sometimes called evolving constants of motion. There has been some discussion in the literature about the interpretation of such observables, and in particular whether single Dirac observables can be measured. Here we clarify the situation by describing a class of interactions that can be said to implement measurements of such observables. Along the way, we describe a useful notion of perturbation theory for the rigging map eta of group averaging (sometimes loosely called the physical state "projector"), which maps states from the auxiliary Hilbert space to the physical Hilbert space.Comment: 12 pages, ReVTe

Variational Principle for Mixed Classical-Quantum Systems

An extended variational principle providing the equations of motion for a system consisting of interacting classical, quasiclassical and quantum components is presented, and applied to the model of bilinear coupling. The relevant dynamical variables are expressed in the form of a quantum state vector which includes the action of the classical subsystem in its phase factor. It is shown that the statistical ensemble of Brownian state vectors for a quantum particle in a classical thermal environment can be described by a density matrix evolving according to a nonlinear quantum Fokker-Planck equation. Exact solutions of this equation are obtained for a two-level system in the limit of high temperatures, considering both stationary and nonstationary initial states. A treatment of the common time shared by the quantum system and its classical environment, as a collective variable rather than as a parameter, is presented in the Appendix.Comment: 16 pages, LaTex; added Figure 2 and Figure

Evolutionary quantum cosmology in a gauge-fixed picture

We study the classical and quantum models of a flat Friedmann-Robertson-Walker (FRW) space-time, coupled to a perfect fluid, in the context of the consensus and a gauge-fixed Lagrangian frameworks. It is shown that, either in the usual or in the gauge-fixed actions, the evolution of the universe based on the classical cosmology represents a late time power law expansion, coming from a big-bang singularity in which the scale factor goes to zero for the standard matter, and tending towards a big-rip singularity in which the scale factor diverges for the phantom fluid. We then employ the familiar canonical quantization procedure in the given cosmological setting to find the cosmological wave functions in the corresponding minisuperspace. Using a gauge-fixed (reduced) Lagrangian, we show that, it may lead to a Schr\"{o}dinger equation for the quantum-mechanical description of the model under consideration, the eigenfunctions of which can be used to construct the time dependent wave function of the universe. We use the resulting wave function in order to investigate the possibility of the avoidance of classical singularities due to quantum effects by means of the many-worlds and ontological interpretation of quantum cosmology.Comment: 15 pages, 10 figures, typos corrected, Refs. adde

Instability of Magnons in Two-dimensional Antiferromagnet at High Magnetic Fields

Spin dynamics of the square lattice Heisenberg antiferromagnet, \BaMnGeO, is studied by a combination of bulk measurements, neutron diffraction, and inelastic neutron scattering techniques. Easy plane type antiferromagnetic order is identified at $T \le 4.0$ K. The exchange interactions are estimated as $J_1$ = 27.8(3)${\mu}$eV and $J_2$ = 1.0(1) ${\mu}$eV, and the saturation field $H_{\rm C}$ is 9.75 T. Magnetic excitation measurements with high experimental resolution setup by triple axis neutron spectrometer reveals the instability of one magnon excitation in the field range of $0.7H_{\rm C} \lesssim H \lesssim 0.85H_{\rm C}$.Comment: 5 pgase, 5 figuers, to be published in PRB R

Felines Sarcoid bei einer 1-jährigen europäischen Hauskatze ausgelöst durch bovines Papillomavirus Typ 14 in der Schweiz

Eine einjährige Bauernhofkatze zeigte einen 5 cm grossen Knoten an der linken Nasenöffnung, der aufgrund seiner Lokalisation nur unvollständig entfernt werden konnte. Hinsichtlich der infiltrativ wachsenden, spindelförmigen Proliferation wurde histologisch ein felines Sarkoid diagnostiziert. Die aus dem Gewebe isolierte DNA konnte durch zwei PCRs als solche von bovinem Papillomavirus 14 (BPV-14) identifiziert werden. Die 194 und 549 Basenpaare (bp) langen, amplifizierten Sequenzen waren 99 bzw. 100% identisch mit einer von einem in den USA isolierten Virus, welches mit felinem Sarkoid in Zusammenhang gebracht wurde. Trotz unvollständiger Exzision, ist bis 10 Monate nach der Operation kein Rezidiv aufgetreten

Signatures of magnetic activity in the seismic data of solar-type stars observed by Kepler

In the Sun, the frequencies of the acoustic modes are observed to vary in phase with the magnetic activity level. These frequency variations are expected to be common in solar-type stars and contain information about the activity-related changes that take place in their interiors. The unprecedented duration of Kepler photometric time-series provides a unique opportunity to detect and characterize stellar magnetic cycles through asteroseismology. In this work, we analyze a sample of 87 solar-type stars, measuring their temporal frequency shifts over segments of length 90 days. For each segment, the individual frequencies are obtained through a Bayesian peak-bagging tool. The mean frequency shifts are then computed and compared with: 1) those obtained from a cross-correlation method; 2) the variation in the mode heights; 3) a photometric activity proxy; and 4) the characteristic timescale of the granulation. For each star and 90-d sub-series, we provide mean frequency shifts, mode heights, and characteristic timescales of the granulation. Interestingly, more than 60% of the stars show evidence for (quasi-)periodic variations in the frequency shifts. In the majority of the cases, these variations are accompanied by variations in other activity proxies. About 20% of the stars show mode frequencies and heights varying approximately in phase, in opposition to what is observed for the Sun.Comment: Accepted for publication in ApJS, 19(+86) pages, 11(+89) figures, 2(+87) table