729 research outputs found
Widespread Expression of BORIS/CTCFL in Normal and Cancer Cells
No full textThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Spontaneous polariton currents in periodic lateral chains
No full textWe predict spontaneous generation of superfluid polariton currents in planar microcavities with lateral periodic modulation of both the potential and decay rate. A spontaneous breaking of spatial inversion symmetry of a polariton condensate emerges at a critical pumping, and the current direction is stochastically chosen. We analyze the stability of the current with respect to the fluctuations of the condensate. A peculiar spatial current domain structure emerges, where the current direction is switched at the domain walls, and the characteristic domain size and lifetime scale with the pumping power
Efficient Population Transfer via Non-Ergodic Extended States in Quantum Spin Glass
No full textQuantum tunneling has been proposed as a physical mechanism for solving binary optimization problems on a quantum computer because it provides an alternative to simulated annealing by directly connecting deep local minima of the energy landscape separated by large Hamming distances. However, classical simulations using Quantum Monte Carlo (QMC) were found to efficiently simulate tunneling transitions away from local minima if the tunneling is effectively dominated by a single path. We analyze a new computational role of coherent multi-qubit tunneling that gives rise to bands of non-ergodic extended (NEE) quantum states each formed by a superposition of a large number of deep local minima with similar energies. NEE provide a coherent pathway for population transfer (PT) between computational states with similar energies. In this regime, PT cannot be efficiently simulated by QMC. PT can serve as a new quantum subroutine for quantum search, quantum parallel tempering and reverse annealing optimization algorithms. We study PT resulting from quantum evolution under a transverse field of an n-spin system that encodes the energy function E(z) of an optimization problem over the set of bit configurations z. Transverse field is rapidly switched on in the beginning of algorithm, kept constant for sufficiently long time and switched off at the end. Given an energy function of a binary optimization problem and an initial bit-string with atypically low energy, PT protocol searches for other bitstrings at energies within a narrow window around the initial one. We provide an analytical solution for PT in a simple yet nontrivial model: M randomly chosen marked bit-strings are assigned energies E(z) within a narrow strip [-n -W/2, n + W/2], while the rest of the states are assigned energy 0. The PT starts at a marked state and ends up in a superposition of L marked states inside the narrow energy window whose width is smaller than W. The best known classical algorithm for finding another marked state is the exhaustive search. We find that the scaling of a typical PT runtime with n and L is the same as that in the multi-target Grover's quantum search algorithm, except for a factor that is equal to exp(n /(2B^2)) for finite transverse field B >>1. Unlike the Hamiltonians used in analog quantum unstructured search algorithms known so far, the model we consider is non-integrable and the transverse field delocalizes the marked states. As a result, our PT protocol is not exponentially sensitive in n to the weight of the driver Hamiltonian and may be initialized with a computational basis state. We develop the microscopic theory of PT by constructing a down-folded dense Hamiltonian acting in the space of marked states of dimension M. It belongs to the class of preferred basis Levy matrices (PBLM) with heavy-tailed distribution of the off-diagonal matrix elements. Under certain conditions, the band of the marked states splits into minibands of non-ergodic delocalized states. We obtain an explicit form of the heavy-tailed distribution of PT times by solving cavity equations for the ensemble of down-folded Hamiltonians. We study numerically the PT subroutine as a part of quantum parallel tempering algorithm for a number of examples of binary optimization problems on fully connected graphs
Kant’s fundamental idea of state and law in Pushkin’s Boris Godunov
No full textThe tragedy Boris Godunov occupies a unique place in A. S. Pushkin’s oeuvre. It was a turning point, when the author needed the whole power of his poetical genius, when a work beyond traditional literary and aesthetic styles, which interchange and establish a canon of a new style that transforms its predecessors in an act of creativity, appeared in Russian culture. Boris Godunov marked the birth of an individual author’s style in Russian art. A unique literary world — the world of Pushkin — manifested itself in a work of art. This article sets out to prove the influence of Kant’s philosophical and legal ideas on A. S. Pushkin during the poet’s work on Boris Godunov. Kant’s thought that the people is the only monarch and that legislative power is vested in it in a rule-of-law state is the central idea of the tragedy. When working on Boris Godunov, Pushkin not only studied the Critique of Judgement but he also read Kant’s works on epistemological theory. In his tragedy, Pushkin was guided by Kant’s ideas of state and law and strived to make it obvious that the people is the only monarch and source of political and legislative power. The tragedy of the people is that it does not know it and the mission of the educated class is to make the people aware of its powers and educate it. Law cannot exist beyond the people’s consciousness — everything else is despotism and a tyranny
Tax Expenditure Estimation and Reporting: A Critical Review
No full textWe examine the measurement of tax expenditures, as well as review issues concerning the classification of tax expenditures generally. We use calculations from NBER's TAXSIM to illustrate some of the problems with the current methodology for estimating tax expenditures. Unlike most previous work on the topic, we focus on how features of the current tax system including the alternative minimum tax and sunset rules complicate and compromise the value of information provided by the tax expenditure budget.
Simple way to calculate a UV-finite one-loop quantum energy in the Randall-Sundrum model
No full text
-Gamma index theorem for spacetimes
No full textWe establish an -Gamma index theorem for the Dirac operator on a globally hyperbolic manifold with Cauchy hypersurface being a Galois covering of a compact smooth manifold with Galois group . Our argument rewrites the -Gamma index in terms of the spectral flow, which is then connected to the usual geometric expressions. This extends the work of Bär and Strohmaier to some non-compact Cauchy hypersurfaces. The analysis here is based on intermediate results by the first author on -Gamma Fredholm properties of the Dirac operator.27 page
Evaporation plant for condensing of the apple juice
No full textTehnologija uparivanja padajućim filmom često je korištena tehnologija u prehrambenoj i kemijskoj industriji jer predstavlja vrlo učinkovit način ugušćivanja raznih procesnih sirovina. U sklopu ovog rada, projektirano je postrojenje za uparivanje 10000 l/h jabučnog soka s početnog masenog udjela suhe tvari od 10 °Brix-a, na krajnji maseni udio suhe tvari od 70 °Brix-a. Postrojenje se sastoji od spremnika za medij, izmjenjivača topline, dvije spirale za predgrijavanje, četiri uparna tijela, kondenzatora supare, rashladnog tornja, spremnika rashladne vode, jedne vakuum pumpe i osam centrifugalnih pumpi koje pokreću proces.Termodinamičkim proračunom obuhvaćena su četiri stupnja uparnog postrojenja, dvije spirale za predgrijavanje i kondenzator supare. Rashladni toranj i centrifugalne pumpe odabrane su iz kataloga poznatih proizvođača opreme. Posebna pažnja posvećena je proračunu koeficijenta prijelaza topline na unutarnjoj stijenci cijevi. U svrhu tih razmatranja, provjeren je niz modela koji su dostupni u literaturi s iskustvenim i realnim podacima postrojenja u pogonu. U proračunu je korišten model koji se najbolje poklapa s iskustvenim vrijednostima. Glavni elementi postrojenja su konstrukcijski razrađeni, dok je cijelo postrojenje prikazano u 3D modelu. Opisani proizvodni proces uparivanja moguće je pratiti u izrađenom P and I dijagramu uz tehnički opis svih elemenata. Napravljena je i analiza termodinamičkog proračuna, gdje su opisani utjecaji pojedinih projektnih veličina. U zaključku ovog rada prezentirani su rezultati proračuna te je dan je kratak osvrt i komentar autora.Falling film evaporation technology is often used in food and chemical industry because it represents a very effective way of condensing various process fluids. In this project, an evaporation plant is designed for evaporating 10000 lit / h of apple juice from an initial dry solid weight content of 10 ° Brix, to the final mass fraction of solids of 70 ° Brix. Plant consists of a feed tank, a heat exchanger, two coils for preheating, four calandrias, one condenser, a cooling tower, a cooling water tank, one vacuum pump and eight centrifugal pumps. Thermodynamic calculation covers four effects of evaporating plants, two coils for preheating and vapour condenser. Cooling tower and centrifugal pumps were selected from well-known manufacturers. Special attention was paid on calculating a falling film heat transfer coefficients. A number of models that are available in the literature are tested with empirical and realistic data from plants already in operation. Calculation which best fits the empirical values has been used. The main elements of the plant are developed and designed in a 3D model programme . The manufacturing process is described and presented in a P & I diagram with a technical description of all the elements. A short analysis of thermodynamic calculations is made and influence of selected design parameters on a thermodynamic calculation is given. In conclusion of this study, the results of the calculations are presented and a brief review and comment of the author is given
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