2,914 research outputs found
Similarity of Operators in the Bergman Space Setting
We give a necessary and sufficient condition for an n-hypercontraction to be
similar to the backward shift operator in a weighted Bergman space. This
characterization serves as a generalization of the description given in the
Hardy space setting, where the geometry of the eigenvector bundles of the
operators is used
EVALUATING A PRECISION AGRICULTURE HERBICIDE DECISION MODEL FOR WINTER WHEAT
Replaced with revised version of paper 08/02.Crop Production/Industries,
Identifying Mode Confusion in Recorded Aircraft Data
In recent decades, commercial aviation accidents have occurred due to human-machine interaction (HMI) problems known as “mode confusion.” This is caused, in some cases, by a lack of understanding of onboard systems by pilots. Large amounts of Flight Operational Quality Assurance (FOQA) data are available, analysis of which could assist in identification of safety risks in daily operations. Through analysis of pilot reactions and recorded aircraft data, methods to detect mode confusion are developed to improve aviation safety. This study was conducted by inducing mode confusion into a flight simulation scenario and analyzing aircraft data to detect emerging patterns. Three distinct Instrument Landing System approaches were flown by participants unaware of experiment details. Differences between these approaches force the pilot to capture the glideslope from above using automation. The results indicate that pilots reacted to the mode confusion by providing control input which opposed the goal of the automation. This reaction was a response to the divergence between pilot intent and automation intent. Further experimentation is needed to determine a general, universally accepted data marker for the occurrence of mode confusion. Ultimately, this outcome will assist the aviation community in addressing drawbacks of modern automation
Applications of Hilbert Module Approach to Multivariable Operator Theory
A commuting -tuple of bounded linear operators on a
Hilbert space \clh associate a Hilbert module over
in the following sense: where and
. A companion survey provides an introduction to the theory
of Hilbert modules and some (Hilbert) module point of view to multivariable
operator theory. The purpose of this survey is to emphasize algebraic and
geometric aspects of Hilbert module approach to operator theory and to survey
several applications of the theory of Hilbert modules in multivariable operator
theory. The topics which are studied include: generalized canonical models and
Cowen-Douglas class, dilations and factorization of reproducing kernel Hilbert
spaces, a class of simple submodules and quotient modules of the Hardy modules
over polydisc, commutant lifting theorem, similarity and free Hilbert modules,
left invertible multipliers, inner resolutions, essentially normal Hilbert
modules, localizations of free resolutions and rigidity phenomenon.
This article is a companion paper to "An Introduction to Hilbert Module
Approach to Multivariable Operator Theory".Comment: 46 pages. This is a companion paper to arXiv:1308.6103. To appear in
Handbook of Operator Theory, Springe
Interactions in sustainable supply chain management: a framework review
Purpose – This study evaluates the research conducted among the interim, dyadic interactions that bridge the stand-alone measures of economic, environmental, and social performance and the level of sustainability, as suggested in the Carter & Rogers (2008) framework.
Design/methodology/approach – This paper conducts a systematic literature review based on the Tranfield et al. (2003) method of the articles published in 13 major journals in the area of supply chain management between the years of 2010 and 2016. Results were analyzed using an expert panel.
Findings – The area of research between environmental and social performance is sparse and relegated to empirical investigation. As an important area of interaction, this area needs more research to answer the how and why questions. The economic activity seems to be the persistent theme among the interactions.
Research implications – The literature on the “ES” interactions is lacking in both theoretical and analytical content. Studies explaining the motivations, optimal levels, and context that drive these interactions are needed. The extant research portrays economic performance as if it cannot be sacrificed for social welfare. This approach is not in line with the progressive view of SSCM but instead the binary view with an economic emphasis.
Practical implications – To improve sustainability, organizations need the triple bottom line (TBL) framework that defines sustainability in isolation. However, they also need to understand how and why these interactions take place that drive sustainability in organizations.
Originality/value – This is the first study to examine the literature specifically dedicated to the essential, interim, dyadic interactions that bridge the gap between stand-alone performance and the TBL that creates true sustainability. It also shows how the literature views the existence of sustainability is progressive, but many describe sustainability as binary. It is possible that economic sustainability is binary, and progressive characterizations of SSCM could be the reason behind the results favoring economic performance over environmental and social
Electrostatic theory for designing lossless negative permittivity metamaterials
In this Letter, we develop an electrostatic theory for designing bulk
composites with effective lossless negative permittivities. The theory and
associated design procedure are validated by comparing their predictions with
those of rigorous full-wave simulations. It is demonstrated that the excitation
of the Frohlich mode (the first-order surface mode) of the constitutive
nanoparticles plays a key role in achieving negative permittivities with
compensated losses.Comment: 9 pages, 2 figure
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PD-1, IL-10, IFN-γ and IL-12 Form a Network to Regulate HIV-1-Specific CD4 T Cell and Antigen-Presenting Cell Function
Winding Strings and Decay of D-Branes with Flux
We study the boundary state associated with the decay of an unstable D-brane
with uniform electric field, 1>e>0 in the string units. Compactifying the
D-brane along the direction of the electric field, we find that the decay
process is dominated by production of closed strings with some winding numbers;
closed strings produced are such that the winding mode carries precisely the
fraction of the individual string energy. This supports the conjecture that
the final state at tree level is composed of winding strings with heavy
oscillations turned on. As a corollary, we argue that the closed strings
disperse into spacetime at a much slower rate than the case without electric
field.Comment: 14 pages, harvmac, minor changes, clarified gauge choice, version to
appear in JHE
Open/Closed Duality, Unstable D-Branes, and Coarse-Grained Closed Strings
At the final stage of unstable D-brane decay in the effective field theory
approach, all energy and momentum of the initial state are taken up by two
types of fluids, known as string fluid and tachyon matter. In this note, we
compare motion of this fluid system to that of macroscopic collection of
stretched closed strings and find a precise match at classical level. The
string fluid reflects low frequency undulation of the stretched strings while
the tachyon matter encodes the average effect of high frequency oscillations
turned on those strings. In particular, the combined fluid system has been
known to have a reduced speed of light, depending on the composition, and we
show that this property is exactly reproduced in classical motion on the closed
string side. Finally we illustrate how the tachyon matter may be viewed as an
effective degrees of freedom carrying high frequency energy-momentum of
Nambu-Goto strings by coarse-graining the dynamics of the latter.Comment: LaTeX, 29 pages, 4 figure file
Electron Tomography of HIV-1 Infection in Gut-Associated Lymphoid Tissue
Critical aspects of HIV-1 infection occur in mucosal tissues, particularly in the gut, which contains large numbers of HIV-1 target cells that are depleted early in infection. We used electron tomography (ET) to image HIV-1 in gut-associated lymphoid tissue (GALT) of HIV-1–infected humanized mice, the first three-dimensional ultrastructural examination of HIV-1 infection in vivo. Human immune cells were successfully engrafted in the mice, and following infection with HIV-1, human T cells were reduced in GALT. Virions were found by ET at all stages of egress, including budding immature virions and free mature and immature viruses. Immuno-electron microscopy verified the virions were HIV-1 and showed CD4 sequestration in the endoplasmic reticulum of infected cells. Observation of HIV-1 in infected GALT tissue revealed that most HIV-1–infected cells, identified by immunolabeling and/or the presence of budding virions, were localized to intestinal crypts with pools of free virions concentrated in spaces between cells. Fewer infected cells were found in mucosal regions and the lamina propria. The preservation quality of reconstructed tissue volumes allowed details of budding virions, including structures interpreted as host-encoded scission machinery, to be resolved. Although HIV-1 virions released from infected cultured cells have been described as exclusively mature, we found pools of both immature and mature free virions within infected tissue. The pools could be classified as containing either mostly mature or mostly immature particles, and analyses of their proximities to the cell of origin supported a model of semi-synchronous waves of virion release. In addition to HIV-1 transmission by pools of free virus, we found evidence of transmission via virological synapses. Three-dimensional EM imaging of an active infection within tissue revealed important differences between cultured cell and tissue infection models and furthered the ultrastructural understanding of HIV-1 transmission within lymphoid tissue
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