354 research outputs found
Modeling Web Services by Iterative Reformulation of Functional and Non-Functional Requirements
Abstract. We propose an approach for incremental modeling of composite Web services. The technique takes into consideration both the functional and nonfunctional requirements of the composition. While the functional requirements are described using symbolic transition systems—transition systems augmented with state variables, function invocations, and guards; non-functional requirements are quantified using thresholds. The approach allows users to specify an abstract and possibly incomplete specification of the desired service (goal) that can be realized by selecting and composing a set of pre-existing services. In the event that such a composition is unrealizable, i.e. the composition is not functionally equivalent to the goal or the non-functional requirements are violated, our system provides the user with the causes for the failure, that can be used to appropriately reformulate the functional and/or non-functional requirements of the goal specification.
Geometric Transitions, Flops and Non-Kahler Manifolds: I
We construct a duality cycle which provides a complete supergravity
description of geometric transitions in type II theories via a flop in
M-theory. This cycle connects the different supergravity descriptions before
and after the geometric transitions. Our construction reproduces many of the
known phenomena studied earlier in the literature and allows us to describe
some new and interesting aspects in a simple and elegant fashion. A precise
supergravity description of new torsional manifolds that appear on the type IIA
side with branes and fluxes and the corresponding geometric transition are
obtained. A local description of new G_2 manifolds that are circle fibrations
over non-Kahler manifolds is presented.Comment: Harvmac, 79 pages, 1 .eps figure; v4: Text further expanded with
additional results, typos corrected and references adde
In the Realm of the Geometric Transitions
We complete the duality cycle by constructing the geometric transition duals
in the type IIB, type I and heterotic theories. We show that in the type IIB
theory the background on the closed string side is a Kahler deformed conifold,
as expected, even though the mirror type IIA backgrounds are non-Kahler (both
before and after the transition). On the other hand, the Type I and heterotic
backgrounds are non-Kahler. Therefore, on the heterotic side these backgrounds
give rise to new torsional manifolds that have not been studied before. We show
the consistency of these backgrounds by verifying the torsional equation.Comment: 60 pages, 2 .eps figures, Harvmac; v2: Minor typos corrected and
references added; v3: Some more typos corrected. Final version to appear in
Nucl. Phys.
Technology maturity for the habitable-zone exoplanet imaging observatory (HabEx) concept
HabEx Architecture A is a 4m unobscured telescope mission concept optimized for direct imaging and spectroscopy of potentially habitable exoplanets, and also enables a wide range of general astrophysics science. The exoplanet detection and characterization drives the enabling core technologies. A hybrid starlight suppression approach of a starshade and coronagraph diversifies technology maturation risk. In this paper we assess these exoplanet-driven technologies, including elements of coronagraphs, starshades, mirrors, jitter mitigation, wavefront control, and detectors. By utilizing high technology readiness solutions where feasible, and identifying required technology development that can begin early, HabEx will be well positioned for assessment by the community in 2020 Astrophysics Decadal Survey
Identification of Enhancer of Zeste Homolog 2 Expression in Peripheral Circulating Tumor Cells in Metastatic Prostate Cancer Patients: A Preliminary Study
transcriptional repressor, is reportedly over-expressed in metastatic prostate cancer. In this study, we analyzed EZH2 mRNA in circulating tumor cells (CTCs) in peripheral blood as a biomarker in patients with metastatic prostate cancer. Patients and Methods: Ber-EP4 coated immunomagnetic beads were used to harvest CTCs, and mRNA was isolated by oligodT conjugated immunomagnetic beads. Reverse transcriptasepolymerase chain reaction for EZH2 mRNA was performed and the expression density was measured. The sensitivity of this test for detection of EZH2 mRNA was determined by serial dilutions of a human prostate cancer cell line. Blood samples were collected from 20 patients each with metastatic or localized prostate cancer and 10 healthy volunteers. Results: Sensitivity experiments showed that the test was highly sensitive as it could detect 10 tumor cells per 5 mL. EZH2 mRNA expression was obtained from peripheral blood samples of patients and control subjects. EZH2 mRNA expression density in the metastatic prostate cancer group was significantly higher than in the control (p = 0.023) and localized prostate cancer groups (p = 0.019). There was no difference between the control and localized prostate cancer groups (p> 0.05). Conclusion: EZH2 mRNA expression in circulating epithelial cells represents a promising marker for detecting early metastasis in prostate cancer. However, more specific and sensitive techniques for detection of CTCs are needed to avoid mononuclear cell contamination
Gauge-Gravity Dualities, Dipoles and New Non-Kahler Manifolds
In this work we explore many directions in the framework of gauge-gravity
dualities. In type IIB theory we give an explicit derivation of the local
metric for five branes wrapped on rigid two-cycles. Our derivation involves
various interplays between warp factors, dualities and fluxes and the final
result confirms our earlier predictions. We also find a novel dipole-like
deformation of the background due to an inherent orientifold projection in the
full global geometry. The supergravity solution for this deformation takes into
account various things like the presence of a non-trivial background topology
and fluxes as well as branes. Considering these, we manage to calculate the
precise local solution using equations of motion. We also show that this
dipole-like deformation has the desired property of decoupling the Kaluza-Klein
modes from the IR gauge theory. Finally, for the heterotic theory we find new
non-Kahler complex manifolds that partake in the full gauge-gravity dualities
and study the mathematical structures of these manifolds including the torsion
classes, Betti numbers and other topological data.Comment: Harvmac, 80 pages, 4 .eps figures; v2: Some typos corrected and new
references added; v3: More typos corrected and references updated. Final
version to appear in Nucl. Phys.
Compactifications of Heterotic Strings on Non-Kahler Complex Manifolds: II
We continue our study of heterotic compactifications on non-Kahler complex
manifolds with torsion. We give further evidence of the consistency of the
six-dimensional manifold presented earlier and discuss the anomaly cancellation
and possible supergravity description for a generic non-Kahler complex manifold
using the newly proposed superpotential. The manifolds studied in our earlier
papers had zero Euler characteristics. We construct new examples of non-Kahler
complex manifolds with torsion in lower dimensions, that have non-zero Euler
characteristics. Some of these examples are constructed from consistent
backgrounds in F-theory and therefore are solutions to the string equations of
motion. We discuss consistency conditions for compactifications of the
heterotic string on smooth non-Kahler manifolds and illustrate how some results
well known for Calabi-Yau compactifications, including counting the number of
generations, apply to the non-Kahler case. We briefly address various issues
regarding possible phenomenological applications.Comment: 106 pages, 8 .eps figures, Harvmac; v2: Some sections expanded, typos
corrected and references updated; v3: More typos corrected, one section
expanded and references added. Final version to appear in Nucl. Phys.
An epitaxial model for heterogeneous nucleation on potent substrates
© The Minerals, Metals & Materials Society and ASM International 2012In this article, we present an epitaxial model for heterogeneous nucleation on potent substrates. It is proposed that heterogeneous nucleation of the solid phase (S) on a potent substrate (N) occurs by epitaxial growth of a pseudomorphic solid (PS) layer on the substrate surface under a critical undercooling (ΔT ). The PS layer with a coherent PS/N interface mimics the atomic arrangement of the substrate, giving rise to a linear increase of misfit strain energy with layer thickness. At a critical thickness (h ), elastic strain energy reaches a critical level, at which point, misfit dislocations are created to release the elastic strain energy in the PS layer. This converts the strained PS layer to a strainless solid (S), and changes the initial coherent PS/N interface into a semicoherent S/N interface. Beyond this critical thickness, further growth will be strainless, and solidification enters the growth stage. It is shown analytically that the lattice misfit (f) between the solid and the substrate has a strong influence on both h and ΔT ; h decreases; and ΔT increases with increasing lattice misfit. This epitaxial nucleation model will be used to explain qualitatively the generally accepted experimental findings on grain refinement in the literature and to analyze the general approaches to effective grain refinement.EPSRC Centre for Innovative Manufacturing in Liquid Metal Engineerin
Machine Learning in Automated Text Categorization
The automated categorization (or classification) of texts into predefined
categories has witnessed a booming interest in the last ten years, due to the
increased availability of documents in digital form and the ensuing need to
organize them. In the research community the dominant approach to this problem
is based on machine learning techniques: a general inductive process
automatically builds a classifier by learning, from a set of preclassified
documents, the characteristics of the categories. The advantages of this
approach over the knowledge engineering approach (consisting in the manual
definition of a classifier by domain experts) are a very good effectiveness,
considerable savings in terms of expert manpower, and straightforward
portability to different domains. This survey discusses the main approaches to
text categorization that fall within the machine learning paradigm. We will
discuss in detail issues pertaining to three different problems, namely
document representation, classifier construction, and classifier evaluation.Comment: Accepted for publication on ACM Computing Survey
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