653 research outputs found
One-way quantum computing with arbitrarily large time-frequency continuous-variable cluster states from a single optical parametric oscillator
One-way quantum computing is experimentally appealing because it requires
only local measurements on an entangled resource called a cluster state.
Record-size, but non-universal, continuous-variable cluster states were
recently demonstrated separately in the time and frequency domains. We propose
to combine these approaches into a scalable architecture in which a single
optical parametric oscillator and simple interferometer entangle up to
( frequencies) (unlimited number of temporal modes) into
a new and computationally universal continuous-variable cluster state. We
introduce a generalized measurement protocol to enable improved computational
performance on this new entanglement resource.Comment: (v4) Consistent with published version; (v3) Fixed typo in arXiv
abstract, 14 pages, 8 figures; (v2) Supplemental material incorporated into
main text, additional explanations added, results unchanged, 14 pages, 8
figures; (v1) 5 pages (3 figures) + 6 pages (5 figures) of supplemental
material; submitted for publicatio
Gravity wave momentum flux in the lower stratosphere over convection
This work describes a method for estimating vertical fluxes of horizontal momentum carried by short horizontal scale gravity waves (lambda(sub x) = 10-100 km) using aircraft measured winds in the lower stratosphere. We utilize in situ wind vector and pressure altitude measurements provided by the Meteorological Measurement System (MMS) on board the ER-2 aircraft to compute the momentum flux vectors at the flight level above deep convection during the tropical experiment of the Stratosphere Troposphere Exchange Project (STEP-Tropical). Data from Flight 9 are presented here for illustration. The vertical flux of horizontal momentum these observations points in opposite directions on either side of the location of a strong convective updraft in the cloud shield. This property of internal gravity waves propagating from a central source compares favorably with previously described model results
Critical region for droplet formation in the two-dimensional Ising model
We study the formation/dissolution of equilibrium droplets in finite systems
at parameters corresponding to phase coexistence. Specifically, we consider the
2D Ising model in volumes of size , inverse temperature \beta>\betac and
overall magnetization conditioned to take the value \mstar L^2-2\mstar v_L,
where \betac^{-1} is the critical temperature, \mstar=\mstar(\beta) is the
spontaneous magnetization and is a sequence of positive numbers. We find
that the critical scaling for droplet formation/dissolution is when tends to a definite limit. Specifically, we identify a dimensionless
parameter , proportional to this limit, a non-trivial critical value
\Deltac and a function such that the following holds: For
\Delta<\Deltac, there are no droplets beyond scale, while for
\Delta>\Deltac, there is a single, Wulff-shaped droplet containing a fraction
\lambda_\Delta\ge\lamc=2/3 of the magnetization deficit and there are no
other droplets beyond the scale of . Moreover, and
are related via a universal equation that apparently is independent of
the details of the system.Comment: 48 pages, 2 figures, version to appear in Commun. Math. Phy
Spatial Optical Solitons due to Multistep Cascading
We introduce a novel class of parametric optical solitons supported
simultaneously by two second-order nonlinear cascading processes,
second-harmonic generation and sum-frequency mixing. We obtain, analytically
and numerically, the solutions for three-wave spatial solitons and show that
the presence of an additional cascading mechanism can change dramatically the
properties and stability of two-wave quadratic solitary waves.Comment: 6 pages, 4 figure
LineUp: Visual Analysis of Multi-Attribute Rankings
Rankings are a popular and universal approach to structuring otherwise unorganized collections of items by computing a rank for each item based on the value of one or more of its attributes. This allows us, for example, to prioritize tasks or to evaluate the performance of products relative to each other. While the visualization of a ranking itself is straightforward, its interpretation is not, because the rank of an item represents only a summary of a potentially complicated relationship between its attributes and those of the other items. It is also common that alternative rankings exist which need to be compared and analyzed to gain insight into how multiple heterogeneous attributes affect the rankings. Advanced visual exploration tools are needed to make this process efficient. In this paper we present a comprehensive analysis of requirements for the visualization of multi-attribute rankings. Based on these considerations, we propose LineUp - a novel and scalable visualization technique that uses bar charts. This interactive technique supports the ranking of items based on multiple heterogeneous attributes with different scales and semantics. It enables users to interactively combine attributes and flexibly refine parameters to explore the effect of changes in the attribute combination. This process can be employed to derive actionable insights as to which attributes of an item need to be modified in order for its rank to change. Additionally, through integration of slope graphs, LineUp can also be used to compare multiple alternative rankings on the same set of items, for example, over time or across different attribute combinations. We evaluate the effectiveness of the proposed multi-attribute visualization technique in a qualitative study. The study shows that users are able to successfully solve complex ranking tasks in a short period of time.Engineering and Applied Science
Mechanisms of Brain Injury in Bacterial Meningitis: Workshop Summary
Morbidity and mortality associated with bacterial meningitis remain high, although antibiotic therapy has improved during recent decades. The major intracranial complications of bacterial meningitis are cerebrovascular arterial and venous involvement, brain edema, and hydrocephalus with a subsequent increase of intracranial pressure. Experiments in animal models and cell culture systems have focused on the pathogenesis and pathophysiology of bacterial meningitis in an attempt to identify the bacterial and/or host factors responsible for brain injury during the course of infection. An international workshop entitled "Bacterial Meningitis: Mechanisms of Brain Injury” was organized by the Department of Neurology at the University of Munich and was held in Eibsee, Germany, in June 1993. This conference provided a forum for the exchange of current information on bacterial meningitis, including data on the clinical spectrum of complications, the associated morphological alterations, the role of soluble inflammatory mediators (in particular cytokines) and of leukocyte-endothelial cell interactions in tissue injury, and the molecular mechanisms of neuronal injury, with potential mediators such as reactive oxygen species, reactive nitrogen species, and excitatory amino acids. It is hoped that a better understanding of the pathophysiological events that take place during bacterial meningitis will lead to the development of new therapeutic regimen
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Entourage: Visualizing Relationships between Biological Pathways using Contextual Subsets
Biological pathway maps are highly relevant tools for many tasks in molecular biology. They reduce the complexity of the overall biological network by partitioning it into smaller manageable parts. While this reduction of complexity is their biggest strength, it is, at the same time, their biggest weakness. By removing what is deemed not important for the primary function of the pathway, biologists lose the ability to follow and understand cross-talks between pathways. Considering these cross-talks is, however, critical in many analysis scenarios, such as judging effects of drugs. In this paper we introduce Entourage, a novel visualization technique that provides contextual information lost due to the artificial partitioning of the biological network, but at the same time limits the presented information to what is relevant to the analyst’s task. We use one pathway map as the focus of an analysis and allow a larger set of contextual pathways. For these context pathways we only show the contextual subsets, i.e., the parts of the graph that are relevant to a selection. Entourage suggests related pathways based on similarities and highlights parts of a pathway that are interesting in terms of mapped experimental data. We visualize interdependencies between pathways using stubs of visual links, which we found effective yet not obtrusive. By combining this approach with visualization of experimental data, we can provide domain experts with a highly valuable tool. We demonstrate the utility of Entourage with case studies conducted with a biochemist who researches the effects of drugs on pathways. We show that the technique is well suited to investigate interdependencies between pathways and to analyze, understand, and predict the effect that drugs have on different cell types.Engineering and Applied Science
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