Excited-state quantum phase transitions in systems with two degrees of freedom: III. Interacting boson systems

The series of articles [Ann. Phys. 345, 73 (2014) and 356, 57 (2015)] devoted to excited-state quantum phase transitions (ESQPTs) in systems with $f=2$ degrees of freedom is continued by studying the interacting boson model of nuclear collective dynamics as an example of a truly many-body system. The intrinsic Hamiltonian formalism with angular momentum fixed to $L=0$ is used to produce a generic first-order ground-state quantum phase transition with an adjustable energy barrier between the competing equilibrium configurations. The associated ESQPTs are shown to result from various classical stationary points of the model Hamiltonian, whose analysis is more complex than in previous cases because of (i) a non-trivial decomposition to kinetic and potential energy terms and (ii) the boundedness of the associated classical phase space. Finite-size effects resulting from a partial separability of both degrees of freedom are analyzed. The features studied here are inherent in a great majority of interacting boson systems.Comment: 14 pages, 6 figure

Excited-state quantum phase transitions

We review the effects of excited-state quantum phase transitions (ESQPTs) in interacting many-body systems with finite numbers of collective degrees of freedom. We classify typical ESQPT signatures in the spectra of energy eigenstates with respect to the underlying classical dynamics and outline a variety of quantum systems in which they occur. We describe thermodynamic and dynamic consequences of ESQPTs, like those in microcanonical thermodynamics, quantum quench dynamics, and in the response to nearly adiabatic or periodic driving. We hint at some generalizations of the ESQPT concept in periodic lattices and in resonant tunneling systems.Comment: 78 pages, 21 figures, review articl

Peres lattices in nuclear structure

A method by Peres is used to draw spectra of the interacting boson model as lattices in the plane of energy versus an arbitrary observable average (or variance). Ordered (disordered) lattices are signatures of regularity (chaos) in both quantum and classical dynamics. The method is also apt to disclose exact or approximate dynamical symmetry.Comment: 3 pages, 2 figure

Coulomb analogy for nonhermitian degeneracies near quantum phase transitions

Degeneracies near the real axis in a complex-extended parameter space of a hermitian Hamiltonian are studied. We present a method to measure distributions of such degeneracies on the Riemann sheet of a selected level and apply it in classification of quantum phase transitions. The degeneracies are shown to behave similarly as complex zeros of a partition function.Comment: 4 page

Introduction : Theorizing Digital Peripheries

The global reach of online platforms and services as well as the globally synchronized flows of audiovisual content might suggest that the global media market is now fully integrated. This book argues contrariwise that the global digital market is far from united and that national borders, center-periphery hierarchies and differences in scale still matter, and perhaps they matter even more than in the analog broadcast era

Design and analysis of electromagnet

Tato práce se zabývá návrhem a analýzou elektromagnetu. První kapitola je úvodem do řešeného problému. Ve druhé kapitole je pojednáno obecně o základních vztazích elektromagnetického pole. Třetí kapitola je věnována principu činnosti a konstrukci elektromagnetů, doplněná o jejich obecné rozdělení. Seznámení s metodou konečných prvků a programem FEMM je náplní čtvrté kapitoly. Pátá kapitola je věnována analýze stejnosměrného elektromagnetu, kapitola šestá analýze jednofázového střídavého elektromagnetu. V sedmé kapitole jsou zhodnoceny a ověřeny výsledky celkové analýzy obou elektromagnetů.This work deals with a proposal and an analysis of electromagnets. The first chapter is an introduction into solve of the problem. In the second chapter there is a general discussion about basic relations of the electromagnetic field. The third chapter is dedicated to the operation principle and construction of electromagnets and is supplemented with their common classification. The fourth chapter introduces the Finite Element Method and the FEMM programm. The fifth chapter is dedicated to the analysis of the DC electromagnet, the sixth chapter analysis single-phase AC electromagnet. In the seventh chapter there is a review of results of general analysis of both electromagnets.

Putative P1B-type ATPase from the bacterium Achromobacter xylosoxidans A8 alters Pb2+/Zn2+/Cd2+-resistance and accumulation in Saccharomyces cerevisiae

AbstractPbtA, a putative P1B-type ATPase from the Gram-negative soil bacterium Achromobacter xylosoxidans A8 responsible for Pb2+/Zn2+/Cd2+-resistance in Escherichia coli, was heterologously expressed in Saccharomyces cerevisiae. When present in Zn2+- and Pb2+/Cd2+-hypersensitive S. cerevisiae strains CM137 and DTY168, respectively, PbtA was able to restore Zn2+- and Pb2+-resistant phenotype. At the same time, the increase of Pb, Zn, and Cd accumulation in yeast was observed. However, Cd2+-tolerance of the pbtA-bearing yeasts dramatically decreased. The PbtA-eGFP fusion protein was localized primarily in the tonoplast and also in the plasma membrane and the perinuclear region corresponding to the endoplasmic reticulum at later growth stages. This indicates that PbtA protein is successfully incorporated into membranes in yeasts. Since PbtA caused a substantial increase of Pb2+/Zn2+-resistance and accumulation in baker's yeast, we propose its further use for the genetic modification of suitable plant species in order to obtain an effective tool for the phytoremediation of sites polluted by toxic transition metals

Design and analysis of PMSM with concentrated winding

Synchronní stroje s permanentními magnety (PMSM) jsou v dnešní době široce využívány v mnoha průmyslových aplikacích. V úvodu této diplomové práce je provedeno seznámení s vlastnostmi a konstrukcí jednotlivých typů synchronních strojů s permanentními magnety. Jsou popsány vlastnosti a možné rozdělení střídavých vinutí. Byl realizován analytický návrh čtyř strojů se dvěma různými typy vinutí. Tyto návrhy byly porovnány se simulacemi provedenými za pomocí programu RMxprt a následně byly jejich vlastnosti ověřeny metodou konečných prvků v programu Maxwell 2D. Na závěr této práce bylo u všech navržených strojů provedeno jejich zhodnocení a porovnání z hlediska užitných vlastností.Permanent magnet synchronous machine (PMSM) are widely used in many industrial applications. This thesis starts with familiarization with the properties and structure of each type of synchronous machines with permanent magnets. Subsequently there are described properties and possible division of AC winding types. Afterward analytical designs of four machines with two different types of winding were realized. These designs were compared by means of simulations using the RMxprt program and their properties were subsequently verified by method of finite element using the Maxwell 2D program. Evaluation and comparison in terms of utility properties for all designs of machines were performed at the conclusion of this thesis.

A revision of the millipede family Paracortinidae (Diplopoda, Callipodida)

The taxonomy of the family Paracortinidae Wang & Zhang, 1993 is revised based on literature, old and recently collected material. A new genus Crassipetalum Akkari & Stoev, gen. nov. is described, to accommodate a new species Crassipetalum magnum Akkari & Stoev, gen. nov. et sp. nov. and a recently described species Crassipetalum inflatum (Chen, Zheng & Jian, 2023), comb. nov. The genus Scotopetalum Shear, 2000 hitherto described for the Vietnamese species S. warreni Shear, 2000 and subsequently synonymised with the genus Paracortina Wang & Zhang, 1993 is here resurrected and supplemented with another species, S. chinensis (Stoev & Geoffroy, 2004), comb. nov., ex Paracortina chinensis Stoev & Geoffroy, 2004. The status of the fourth genus in the family, Angulifemur Zhang, 1997, is reconfirmed. Based on recently collected specimens from China, two new species of the genus Paracortina are described: P. asciformis Akkari & Stoev, sp. nov. (Sichuan Prov., Lixian County) and P. kabaki Akkari & Stoev, sp. nov. (Yunnan, Shangrila County). The Vietnamese species Paracortina multisegmentata Stoev & Geoffroy, 2004 and Paracortina kyrang Nguyen, Stoev, Nguyen & Vu, 2023 are considered of uncertain taxonomic position within Paracortinidae. Differential diagnoses for the proposed genera as well as for all the species are presented, and descriptions or descriptive notes for all the species are provided, using a standardised terminology, and when possible, accompanied by micrographs of the habitus and gonopod structures. An identification key based on gonopod structures is proposed for all the members of the family. A discussion on species affinities, secondary sexual characters, troglomorphic characters, geographical distribution, and habitat preferences are also provided together with a distribution map for all members of the family