11,513 research outputs found
Classical Concepts in Quantum Programming
The rapid progress of computer technology has been accompanied by a
corresponding evolution of software development, from hardwired components and
binary machine code to high level programming languages, which allowed to
master the increasing hardware complexity and fully exploit its potential.
This paper investigates, how classical concepts like hardware abstraction,
hierarchical programs, data types, memory management, flow of control and
structured programming can be used in quantum computing. The experimental
language QCL will be introduced as an example, how elements like irreversible
functions, local variables and conditional branching, which have no direct
quantum counterparts, can be implemented, and how non-classical features like
the reversibility of unitary transformation or the non-observability of quantum
states can be accounted for within the framework of a procedural programming
language.Comment: 11 pages, 4 figures, software available from
http://tph.tuwien.ac.at/~oemer/qcl.html, submitted for QS2002 proceeding
Hydrogen atom in phase space. The Kirkwood-Rihaczek representation
We present a phase-space representation of the hydrogen atom using the
Kirkwood-Rikaczek distribution function. This distribution allows us to obtain
analytical results, which is quite unique because an exact analytical form of
the Wigner functions corresponding to the atom states is not known. We show how
the Kirkwood-Rihaczek distribution reflects properties of the hydrogen atom
wave functions in position and momentum representations.Comment: 5 pages (and 5 figures
Stabilization and control system power sensitivity study
Stabilization and control system sensitivity to power-off failure rate studied by simulated missions using block power switchin
Determination of electromagnetic medium from the Fresnel surface
We study Maxwell's equations on a 4-manifold where the electromagnetic medium
is described by an antisymmetric -tensor . In this setting,
the Tamm-Rubilar tensor density determines a polynomial surface of fourth order
in each cotangent space. This surface is called the Fresnel surface and acts as
a generalisation of the light-cone determined by a Lorentz metric; the Fresnel
surface parameterises electromagnetic wave-speed as a function of direction.
Favaro and Bergamin have recently proven that if has only a principal
part and if the Fresnel surface of coincides with the light cone for a
Lorentz metric , then is proportional to the Hodge star operator of
. That is, under additional assumptions, the Fresnel surface of
determines the conformal class of . The purpose of this paper is
twofold. First, we provide a new proof of this result using Gr\"obner bases.
Second, we describe a number of cases where the Fresnel surface does not
determine the conformal class of the original -tensor . For
example, if is invertible we show that and have
the same Fresnel surfaces.Comment: 23 pages, 1 figur
Inclusive 2H(3He,t) reaction at 2 GeV
The inclusive 2H(3He,t) reaction has been studied at 2 GeV for energy
transfers up to 500 MeV and scattering angles from 0.25 up to 4 degrees. Data
are well reproduced by a model based on a coupled-channel approach for
describing the NN and N Delta systems. The effect of final state interaction is
important in the low energy part of the spectra. In the delta region, the
cross-section is very sensitive to the effects of Delta-N interaction and Delta
N - NN process. The latter has also a large influence well below the pion
threshold. The calculation underestimates the experimental cross-section
between the quasi-elastic and the delta peaks; this is possibly due to
projectile excitation or purely mesonic exchange currents.Comment: 9 pages, 9 figures, accepted for publication in EPJ
Differential gaze behavior towards sexually preferred and non-preferred human figures
The gaze pattern associated with image exploration is a sensitive index of our attention, motivation and preference. To examine whether an individual’s gaze behavior
can reflect his/her sexual interest, we compared gaze patterns of young heterosexual men and women (M = 19.94 years, SD = 1.05) while viewing photos of plain-clothed male and female figures aged from birth to sixty years old. Our analysis revealed a clear gender difference in viewing sexually preferred figure images. Men displayed a distinctive gaze pattern only when viewing twenty-year-old female images, with more fixations and longer viewing time dedicated to the upper body and waist-hip region. Women also
directed more attention at the upper body on female images in comparison to male images, but this difference was not age-specific. Analysis of local image salience revealed that observers’ eye-scanning strategies could not be accounted for by low-level processes, such as analyzing local image contrast and structure, but were associated with
attractiveness judgments. The results suggest that the difference in cognitive processing of sexually preferred and non-preferred figures can be manifested in gaze patterns
associated with figure viewing. Thus, eye-tracking holds promise as a potential sensitive measure for sexual preference, particularly in men
Exactly solvable charged dilaton gravity theories in two dimensions
We find exactly solvable dilaton gravity theories containing a U(1) gauge
field in two dimensional space-time. The classical general solutions for the
gravity sector (the metric plus the dilaton field) of the theories coupled to a
massless complex scalar field are obtained in terms of the stress-energy tensor
and the U(1) current of the scalar field. We discuss issues that arise when we
attempt to use these models for the study of the gravitational back-reaction.Comment: The introductory part is changed. a version to appear in Class.
Quant. Grav. 6 pages, RevTe
Occurrence and diversity of Xanthomonas campestris pv. campestris in vegetable brassica fields in Nepal
Black rot caused by Xanthomonas campestris pv. campestris was found in 28 sampled cabbage fields in five major cabbage-growing districts in Nepal in 2001 and in four cauliflower fields in two districts and a leaf mustard seed bed in 2003. Pathogenic X. campestris pv. campestris strains were obtained from 39 cabbage plants, 4 cauliflower plants, and 1 leaf mustard plant with typical lesions. Repetitive DNA polymerase chain reaction-based fingerprinting (rep-PCR) using repetitive extragenic palindromic, enterobacterial repetitive intergenic consensus, and BOX primers was used to assess the genetic diversity. Strains were also race typed using a differential series of Brassica spp. Cabbage strains belonged to five races (races 1, 4, 5, 6, and 7), with races 4, 1, and 6 the most common. All cauliflower strains were race 4 and the leaf mustard strain was race 6. A dendrogram derived from the combined rep-PCR profiles showed that the Nepalese X. campestris pv. campestris strains clustered separately from other Xanthomonas spp. and pathovars. Race 1 strains clustered together and strains of races 4, 5, and 6 were each split into at least two clusters. The presence of different races and the genetic variability of the pathogen should be considered when resistant cultivars are bred and introduced into regions in Nepal to control black rot of brassicas
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