1,153 research outputs found
Verifying termination and error-freedom of logic programs with block declarations
We present verification methods for logic programs with delay declarations. The verified properties are termination and freedom from errors related to built-ins. Concerning termination, we present two approaches. The first approach tries to eliminate the well-known problem of speculative output bindings. The second approach is based on identifying the predicates for which the textual position of an atom using this predicate is irrelevant with respect to termination.
Three features are distinctive of this work: it allows for predicates to be used in several modes; it shows that block declarations, which are a very simple delay construct, are sufficient to ensure the desired properties; it takes the selection rule into account, assuming it to be as in most Prolog implementations. The methods can be used to verify existing programs and assist in writing new programs
A Multi-User Carrier Structure for Deploying Pegasus-Launched Micro-Satellites
Now that the viability of the Pegasus air launched booster has been demonstrated, it is possible, and indeed appropriate, to devise methods for exploiting the launcher so that it can launch multiple micro-satellites. Such spacecraft may be launched for a single user, or the capacity of a single launcher may be divided among multiple users. In fact, not all of the satellites on a single launch need to be placed into the same orbit. This paper describes a concept, developed by OSC, to place multiple micro-satellites into various orbits using a single Pegasus launch vehicle. The concept makes use of separable \u27\u27pallets which may be stacked, one on top of the other within the Pegasus fairing. Each pallet can have an integral propulsion system and may transport from one to six micro-satellites into an orbit modified from the reference orbit provided by the launch vehicle. Examples are given as to how the system may be used to implement a variety of mission options. If a constellation of communications satellites are deployed by this approach, global coverage can be provided at what is believed to be the lowest cast available today. The mechanical and propulsion system designs of the pallet are discussed and user constraints are reviewed. The performance capability of the Pegasus vehicle is reviewed as it impacts the individual micro-satellite payload mass
Reconstruction of superoperators from incomplete measurements
We present strategies how to reconstruct (estimate) properties of a quantum
channel described by the map E based on incomplete measurements. In a
particular case of a qubit channel a complete reconstruction of the map E can
be performed via complete tomography of four output states E[rho_j ] that
originate from a set of four linearly independent test states j (j = 1, 2, 3,
4) at the input of the channel. We study the situation when less than four
linearly independent states are transmitted via the channel and measured at the
output. We present strategies how to reconstruct the channel when just one, two
or three states are transmitted via the channel. In particular, we show that if
just one state is transmitted via the channel then the best reconstruction can
be achieved when this state is a total mixture described by the density
operator rho = I/2. To improve the reconstruction procedure one has to send via
the channel more states. The best strategy is to complement the total mixture
with pure states that are mutually orthogonal in the sense of the Bloch-sphere
representation. We show that unitary transformations (channels) can be uniquely
reconstructed (determined) based on the information of how three properly
chosen input states are transformed under the action of the channel.Comment: 13 pages, 6 figure
PRM169 The Selection of Appropriate Health State Utility Values (Hsuvs) for Health Technology Assessment (Hta): Lessons To Be Learnt
Assembly of the Inner Perivitelline Layer, a Homo log of the Mammalian Zona Pellucida: An Immunohistochemical and Ultrastructural Study
The avian inner perivitelline layer (IPVL), a homologous structure to the mammalian zona pellucida, is deposited between the granulosa cells and the oocyte cell membrane during folliculogenesis. The glycoprotein meshwork of the IPVL forms a 3-dimensional matrix and possesses important functions in the fertilization process: it contributes to the binding of avian spermatozoa to the oocyte and induces acrosomal exocytosis. In contrast to the zona pellucida of mammals, the IPVL does not prevent the physiological polyspermy found in birds. Previous studies have shown that in the Japanese quail (Cotumix japonica) at least 5 glycoproteins are constituents of the IPVL (ZP1, ZP2, ZP3, ZP4, and ZPD). In this study, we investigated the spatiotennporal assembly pattern of the IPVL during folliculogenesis using immunohistochemical and ultrastructural methods. The obtained results clearly show that these glycoproteins are incorporated into the IPVL at distinct points during follicular development, supporting the hypothesis that ZP2 and ZP4 form a type of prematrix into which ZP1, ZP3, and ZPD are integrated at a later stage of development. Copyright (C) 2011 S. Karger AG, Base
Deriving a preference-based utility measure for cancer patients from the European Organisation for the Research and Treatment of Cancer's Quality of Life Questionnaire C30: a confirmatory versus exploratory approach
Background: Multi attribute utility instruments (MAUIs) are preference-based measures that
comprise a health state classification system (HSCS) and a scoring algorithm that assigns a utility
value to each health state in the HSCS. When developing a MAUI from a health-related quality
of life (HRQOL) questionnaire, first a HSCS must be derived. This typically involves selecting
a subset of domains and items because HRQOL questionnaires typically have too many items
to be amendable to the valuation task required to develop the scoring algorithm for a MAUI.
Currently, exploratory factor analysis (EFA) followed by Rasch analysis is recommended for
deriving a MAUI from a HRQOL measure.
Aim: To determine whether confirmatory factor analysis (CFA) is more appropriate and efficient
than EFA to derive a HSCS from the European Organisation for the Research and Treatment
of Cancer’s core HRQOL questionnaire, Quality of Life Questionnaire (QLQ-C30), given its
well-established domain structure.
Methods: QLQ-C30 (Version 3) data were collected from 356 patients receiving palliative
radiotherapy for recurrent/metastatic cancer (various primary sites). The dimensional structure
of the QLQ-C30 was tested with EFA and CFA, the latter informed by the established QLQC30
structure and views of both patients and clinicians on which are the most relevant items.
Dimensions determined by EFA or CFA were then subjected to Rasch analysis.
Results: CFA results generally supported the proposed QLQ-C30 structure (comparative fit
index =0.99, Tucker–Lewis index =0.99, root mean square error of approximation =0.04). EFA
revealed fewer factors and some items cross-loaded on multiple factors. Further assessment
of dimensionality with Rasch analysis allowed better alignment of the EFA dimensions with
those detected by CFA.
Conclusion: CFA was more appropriate and efficient than EFA in producing clinically interpretable
results for the HSCS for a proposed new cancer-specific MAUI. Our findings suggest
that CFA should be recommended generally when deriving a preference-based measure from a
HRQOL measure that has an established domain structure
Applying Laser Doppler Anemometry inside a Taylor-Couette geometry - Using a ray-tracer to correct for curvature effects
In the present work it will be shown how the curvature of the outer cylinder
affects Laser Doppler anemometry measurements inside a Taylor-Couette
apparatus. The measurement position and the measured velocity are altered by
curved surfaces. Conventional methods for curvature correction are not
applicable to our setup, and it will be shown how a ray-tracer can be used to
solve this complication.
By using a ray-tracer the focal position can be calculated, and the velocity
can be corrected. The results of the ray-tracer are verified by measuring an a
priori known velocity field, and after applying refractive corrections good
agreement with theoretical predictions are found. The methods described in this
paper are applied to measure the azimuthal velocity profiles in high Reynolds
number Taylor-Couette flow for the case of outer cylinder rotation
The Neutralino Sector of the Next-to-Minimal Supersymmetric Standard Model
The Next-to-Minimal Supersymmetric Standard Model (NMSSM) includes a Higgs
iso-singlet superfield in addition to the two Higgs doublet superfields of the
minimal extension. If the Higgs fields remain weakly coupled up to the GUT
scale, as naturally motivated by the concept of supersymmetry, the mixing
between singlet and doublet fields is small and can be treated perturbatively.
The mass spectrum and mixing matrix of the neutralino sector can be analyzed
analytically and the structure of this 5-state system is under good theoretical
control. We also determine decay modes and production channels in sfermion
cascade decays to these particles at the LHC and pair production in e+e-
colliders.Comment: 27 pages, 8 figure
The Neutralino Sector in the U(1)-Extended Supersymmetric Standard Model
Motivated by grand unified theories and string theories we analyze the
general structure of the neutralino sector in the USSM, an extension of the
Minimal Supersymmetric Standard Model that involves a broken extra U(1) gauge
symmetry. This supersymmetric U(1)-extended model includes an Abelian gauge
superfield and a Higgs singlet superfield in addition to the standard gauge and
Higgs superfields of the MSSM. The interactions between the MSSM fields and the
new fields are in general weak and the mixing is small, so that the coupling of
the two subsystems can be treated perturbatively. As a result, the mass
spectrum and mixing matrix in the neutralino sector can be analyzed
analytically and the structure of this 6-state system is under good theoretical
control. We describe the decay modes of the new states and the impact of this
extension on decays of the original MSSM neutralinos, including radiative
transitions in cross-over zones. Production channels in cascade decays at the
LHC and pair production at colliders are also discussed.Comment: 50 pages, 9 figures, equations.sty include
Counterexamples to the maximal p-norm multiplicativity conjecture for all p > 1
For all p > 1, we demonstrate the existence of quantum channels with
non-multiplicative maximal output p-norms. Equivalently, for all p >1, the
minimum output Renyi entropy of order p of a quantum channel is not additive.
The violations found are large; in all cases, the minimum output Renyi entropy
of order p for a product channel need not be significantly greater than the
minimum output entropy of its individual factors. Since p=1 corresponds to the
von Neumann entropy, these counterexamples demonstrate that if the additivity
conjecture of quantum information theory is true, it cannot be proved as a
consequence of any channel-independent guarantee of maximal p-norm
multiplicativity. We also show that a class of channels previously studied in
the context of approximate encryption lead to counterexamples for all p > 2.Comment: Merger of arXiv:0707.0402 and arXiv:0707.3291 containing new and
improved analysis of counterexamples. 17 page
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