89 research outputs found
STUDIES FOR INTAKE STRUCTURES OF FLOOD DETENTION BASINS TO BE ESTABLISHED ALONG THE UPPER RHINE
The regulation of the Upper Rhine between the cities Basel and Mannheim, further its subsequent development for energy production by construction of 10 hydropower plants caused a significant diminution of the natural flood retention areas and consequently an enhancement of the flood peaks. In order to counterbalance this effect three types of measures are considered: 1. special operation mode of the power stations, 2. construction
of flood retention weirs in the by-passed stretch of the Rhine, 3. establishment of flood-retention basins beyond the flood control dykes (levees).
The author has been commissioned to elaborate design proposals for retention basins to be possibly erected in selected regions. Equations for calculation of the filling/emptying times are presented in the paper..
Besides, the headworks (inlet/outlet structures) of the basins have been tested under the guidance of the author in the Theodor-Rehbock Hydraulic Laboratory in order to obtain appropriate designs. The main requirements are: high discharging efficiency, reasonable openings as regards the movable gates, simple safety measures against scouring with respect to the two-direction flow, last but not least some aspects of environmental and landscape protection. The paper describes the results of the scale model tests and shows the design proposal. The discharge measurements in the model manifested a very good agreement with the equations
Hypothesis testing for Gaussian states on bosonic lattices
The asymptotic state discrimination problem with simple hypotheses is
considered for a cubic lattice of bosons. A complete solution is provided for
the problems of the Chernoff and the Hoeffding bounds and Stein's lemma in the
case when both hypotheses are gauge-invariant Gaussian states with
translation-invariant quasi-free parts.Comment: 22 pages, submitted versio
Relation between the Dynamics of the Reduced Purity and Correlations
A general property of the relation between the dynamics of the reduced purity
and correlations is investigated in quantum mechanical systems. We show that a
non-zero time-derivative of the reduced purity of a system implies the
existence of non-zero correlations with its environment under any unbounded
Hamiltonians with finite variance. This shows the role of local dynamical
information on the correlations, as well as the role of correlations in the
mechanism of purity change.Comment: 7 page
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Cultural change in the FCA, PRA & Bank of England: Practising what they preach?
Our report examines how the culture of the financial regulators contributed to the financial crisis. It assesses the actions taken by the UK’s financial regulators to change their culture. It identifies the progress which has been made and the barriers encountered. To gather information we interviewed current and former staff at the regulators together with stakeholders from large and small financial institutions, consumer and SME groups and regulatory experts. The report includes the reactions from staff at the regulators to the cultural change programmes and the perceptions of external stakeholders
Structure of sufficient quantum coarse-grainings
Let H and K be Hilbert spaces and T be a coarse-graining from B(H) to B(K).
Assume that density matrices D_1 and D_2 acting on H are given. In the paper
the consequences of the existence of a coarse-graining S from B(K) to B(H)
satisfying ST(D_1)=D_1 and ST(D_2)=D_2 are given. (This condition means the
sufficiency of T for D_1 and D_2.) Sufficiency implies a particular
decomposition of the density matrices. This decomposition allows to deduce the
exact condition for equality in the strong subadditivity of the von Neumann
entropy.Comment: 13 pages, LATE
Quantum hypothesis testing for quantum Gaussian states: Quantum analogues of chi-square, t and F tests
We treat quantum counterparts of testing problems whose optimal tests are
given by chi-square, t and F tests. These quantum counterparts are formulated
as quantum hypothesis testing problems concerning quantum Gaussian states
families, and contain disturbance parameters, which have group symmetry.
Quantum Hunt-Stein Theorem removes a part of these disturbance parameters, but
other types of difficulty still remain. In order to remove them, combining
quantum Hunt-Stein theorem and other reduction methods, we establish a general
reduction theorem that reduces a complicated quantum hypothesis testing problem
to a fundamental quantum hypothesis testing problem. Using these methods, we
derive quantum counterparts of chi-square, t and F tests as optimal tests in
the respective settings.Comment: 34 pages, 3 figure
On entropy growth and the hardness of simulating time evolution
The simulation of quantum systems is a task for which quantum computers are
believed to give an exponential speedup as compared to classical ones. While
ground states of one-dimensional systems can be efficiently approximated using
Matrix Product States (MPS), their time evolution can encode quantum
computations, so that simulating the latter should be hard classically.
However, one might believe that for systems with high enough symmetry, and thus
insufficient parameters to encode a quantum computation, efficient classical
simulation is possible. We discuss supporting evidence to the contrary: We
provide a rigorous proof of the observation that a time independent local
Hamiltonian can yield a linear increase of the entropy when acting on a product
state in a translational invariant framework. This criterion has to be met by
any classical simulation method, which in particular implies that every global
approximation of the evolution requires exponential resources for any MPS based
method.Comment: 15 pages. v2: Published version, Journal-Ref. adde
Comparative genomics of proteins involved in RNA nucleocytoplasmic export
Background: The establishment of the nuclear membrane resulted in the physical separation of transcription and translation, and presented early eukaryotes with a formidable challenge: how to shuttle RNA from the nucleus to the locus of protein synthesis. In prokaryotes, mRNA is translated as it is being synthesized, whereas in eukaryotes mRNA is synthesized and processed in the nucleus, and it is then exported to the cytoplasm. In metazoa and fungi, the different RNA species are exported from the nucleus by specialized pathways. For example, tRNA is exported by exportin-t in a RanGTP-dependent fashion. By contrast, mRNAs are associated to ribonucleoproteins (RNPs) and exported by an essential shuttling complex (TAP-p15 in human, Mex67-mtr2 in yeast) that transports them through the nuclear pore. The different RNA export pathways appear to be well conserved among members of Opisthokonta, the eukaryotic supergroup that includes Fungi and Metazoa. However, it is not known whether RNA export in the other eukaryotic supergroups follows the same export routes as in opisthokonts.
Methods: Our objective was to reconstruct the evolutionary history of the different RNA export pathways across eukaryotes. To do so, we screened an array of eukaryotic genomes for the presence of homologs of the proteins involved in RNA export in Metazoa and Fungi, using human and yeast proteins as queries.
Results: Our genomic comparisons indicate that the basic components of the RanGTP-dependent RNA pathways are conserved across eukaryotes, and thus we infer that these are traceable to the last eukaryotic common ancestor (LECA). On the other hand, several of the proteins involved in RanGTP-independent mRNA export pathways are less conserved, which would suggest that they represent innovations that appeared later in the evolution of eukaryotes.
Conclusions: Our analyses suggest that the LECA possessed the basic components of the different RNA export mechanisms found today in opisthokonts, and that these mechanisms became more specialized throughout eukaryotic evolution
Description of quantum coherence in thermodynamic processes requires constraints beyond free energy
Recent studies have developed fundamental limitations on nanoscale thermodynamics, in terms of a set of independent free energy relations. Here we show that free energy relations cannot properly describe quantum coherence in thermodynamic processes. By casting time-asymmetry as a quantifiable, fundamental resource of a quantum state, we arrive at an additional, independent set of thermodynamic constraints that naturally extend the existing ones. These asymmetry relations reveal that the traditional Szilárd engine argument does not extend automatically to quantum coherences, but instead only relational coherences in a multipartite scenario can contribute to thermodynamic work. We find that coherence transformations are always irreversible. Our results also reveal additional structural parallels between thermodynamics and the theory of entanglement
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