999 research outputs found
Strong singularity of singular masas in II<sub>1</sub> factors
A singular masa A in a II1 factor N is defined by the property that any unitary w ∈ N for which A=wAw* must lie in A. A strongly singular masa A is one that satisfies the inequality ||EA- EwAw*||∞,2 ≥||w- EA(w)||2
for all unitaries w ∈ N where EA is the conditional expectation of N onto A, and ||⋅||∞,2 is defined for bounded maps Φ : N → N by sup{||Φ (x)||2:x ∈ N,||x||≤1}. Strong singularity easily implies singularity, and the main result of this paper shows the reverse implication
Perturbations of C*-algebraic invariants
Kadison and Kastler introduced a metric on the set of all C*-algebras on a fixed Hilbert space. In this paper structural properties of C*-algebras which are close in this metric are examined. Our main result is that the property of having a positive answer to Kadison’s similarity problem transfers to close C*-algebras. In establishing this result we answer questions about closeness of commutants and tensor products when one algebra satisfies the similarity property. We also examine K-theory and traces of close C*-algebras, showing that sufficiently close algebras have isomorphic Elliott invariants when one algebra has the similarity property
The attitudinal work of news journalism images – a search for visual and verbal analogues
This paper is concerned with the potential of journalistic still images (photographs, pictorial layouts, artwork and political cartooning) to position readers/viewers to take a positive or negative view of the people, events and situations which are the subject matter of news journalism coverage. Referencing prior work by Economou (2009) and Swain (2012), it offers an account of the mechanisms, the particular visual qualities and compositional arrangements, by which such attitudinal effects are achieved. Its primary concern is exploring the grounds by which the mechanisms through which journalistic images activate positive or negative attitudes might be treated as analogous to related verbal expressions of attitude. In developing this discussion, it references and revisits the account of the language of evaluation developed within the Appraisal literature (Martin and White 2005). It proposes that in order to identify analogues to verbal expressions which, on the one hand, explicitly assert attitudinal assessments and which, on the other hand, activate attitudinal positions through implication and association, it is useful to attend to the following issues: (1) the salience or detectability of the author’s subjective presence in the text as the communicative agent who puts an attitudinal meaning into play; (2) the stability of the attitudinal associations of a given expression across multiple contexts of use; (3) the role of the reader in supplying attitudinal interpretations or inferences; (4) the terms under which relations of author-reader solidarity are negotiated or put at risk but the expression currently under consideration
Attitudinal Meanings, Translational Commensurability and Linguistic Relativity
The paper explores how insights developed within the Appraisal framework (Martin and White) into attitudinal meanings can contribute to some key, long-standing debates within translation studies and contrastive linguistics. It proposes that taxonomies developed within Appraisal for categorising diff erent types of positive and negative assessment provide a useful reference point for exploring how principled accounts of translational commensurability and incommensurability might be developed. Specifi cally, some methodologies are discussed for
developing comparative maps of the systems of attitudinal valeur which operate in diff erent languages. Some implications for Appraisal theory itself resulting from the exploration of these cross-linguistic comparison issues are discussed. It is proposed that the taxonomies already formulated within the Appraisal literature to deal with attitudinal meaning may need to be extended in delicacy, if they are to be maximally useful in dealing with such issues.Este ensayo expone de qué manera puede el sistema de la Valoración (Martin and White)
contribuir a los estudios de traducción y de lingüística contrastiva. Las taxonomías desarrolladas
dentro de la Valoración en la categorización de los diferentes tipos de valor positivo
o negativo ofrecen un punto de referencia importante para el estudio de los principios de la
traducción. Se discuten de manera específi ca algunas metodologías para desarrollar mapas
comparativos de los sistemas de valor actitudinal que operan en lenguas diferentes, con
las consiguiente implicaciones para la teoría de la Valoración. Se sugiere además que las
taxonomías ya establecidas dentro del sistema de la Valoración en el área de los signifi cados
actitudinales deben de modifi carse para poder ser aplicadas con efi cacia en la comparación
interlingüístic
The Tensor to Scalar Ratio of Phantom Dark Energy Models
We investigate the anisotropies in the cosmic microwave background in a class
of models which possess a positive cosmic energy density but negative pressure,
with a constant equation of state w = p/rho < -1. We calculate the temperature
and polarization anisotropy spectra for both scalar and tensor perturbations by
modifying the publicly available code CMBfast. For a constant initial curvature
perturbation or tensor normalization, we have calculated the final anisotropy
spectra as a function of the dark energy density and equation of state w and of
the scalar and tensor spectral indices. This allows us to calculate the
dependence of the tensor-to-scalar ratio on w in a model with phantom dark
energy, which may be important for interpreting any future detection of
long-wavelength gravitational waves.Comment: 5 pages, 4 figure
Quantum-fluctuation-induced repelling interaction of quantum string between walls
Quantum string, which was brought into discussion recently as a model for the
stripe phase in doped cuprates, is simulated by means of the
density-matrix-renormalization-group method. String collides with adjacent
neighbors, as it wonders, owing to quantum zero-point fluctuations. The energy
cost due to the collisions is our main concern. Embedding a quantum string
between rigid walls with separation d, we found that for sufficiently large d,
collision-induced energy cost obeys the formula \sim exp (- A d^alpha) with
alpha=0.808(1), and string's mean fluctuation width grows logarithmically \sim
log d. Those results are not understood in terms of conventional picture that
the string is `disordered,' and only the short-wave-length fluctuations
contribute to collisions. Rather, our results support a recent proposal that
owing to collisions, short-wave-length fluctuations are suppressed, but
instead, long-wave-length fluctuations become significant. This mechanism would
be responsible for stabilizing the stripe phase
Renormalization-group running of the cosmological constant and its implication for the Higgs boson mass in the Standard Model
The renormalization-group equation for the zero-point energies associated
with vacuum fluctuations of massive fields from the Standard Model is examined.
Our main observation is that at any scale the running is necessarily dominated
by the heaviest degrees of freedom, in clear contradistinction with the
Appelquist & Carazzone decoupling theorem. Such an enhanced running would
represent a disaster for cosmology, unless a fine-tuned relation among the
masses of heavy particles is imposed. In this way, we obtain for the Higgs mass, a value safely within the unitarity bound, but far
above the more stringent triviality bound for the case when the validity of the
Standard Model is pushed up to the grand unification (or Planck) scale.Comment: 11 pages, LaTex2
Critical temperature for the two-dimensional attractive Hubbard Model
The critical temperature for the attractive Hubbard model on a square lattice
is determined from the analysis of two independent quantities, the helicity
modulus, , and the pairing correlation function, . These
quantities have been calculated through Quantum Monte Carlo simulations for
lattices up to , and for several densities, in the
intermediate-coupling regime. Imposing the universal-jump condition for an
accurately calculated , together with thorough finite-size scaling
analyses (in the spirit of the phenomenological renormalization group) of
, suggests that is considerably higher than hitherto assumed.Comment: 5 pages, 6 figures. Accepted for publication in Phys. Rev.
Directional wind measurement derived from elastic backscatter lidar data in real time
The development of a capability to infer wind velocities simultaneously at a number of ranges along one direction in real time is described. The elastic backscatter lidar data used was obtained using the XM94 lidar, developed by Los Alamos National Laboratory for the US Army Chemical and Biological Detection Command. In some respects this problem is simpler than measuring wind velocities on meso-meteorological scales. Other requirements, particularly high temporal fidelity, have driven the development of faster software algorithms and suggested opportunities for the evolution of the hardware
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