1,699 research outputs found
Do logarithmic proximity measures outperform plain ones in graph clustering?
We consider a number of graph kernels and proximity measures including
commute time kernel, regularized Laplacian kernel, heat kernel, exponential
diffusion kernel (also called "communicability"), etc., and the corresponding
distances as applied to clustering nodes in random graphs and several
well-known datasets. The model of generating random graphs involves edge
probabilities for the pairs of nodes that belong to the same class or different
predefined classes of nodes. It turns out that in most cases, logarithmic
measures (i.e., measures resulting after taking logarithm of the proximities)
perform better while distinguishing underlying classes than the "plain"
measures. A comparison in terms of reject curves of inter-class and intra-class
distances confirms this conclusion. A similar conclusion can be made for
several well-known datasets. A possible origin of this effect is that most
kernels have a multiplicative nature, while the nature of distances used in
cluster algorithms is an additive one (cf. the triangle inequality). The
logarithmic transformation is a tool to transform the first nature to the
second one. Moreover, some distances corresponding to the logarithmic measures
possess a meaningful cutpoint additivity property. In our experiments, the
leader is usually the logarithmic Communicability measure. However, we indicate
some more complicated cases in which other measures, typically, Communicability
and plain Walk, can be the winners.Comment: 11 pages, 5 tables, 9 figures. Accepted for publication in the
Proceedings of 6th International Conference on Network Analysis, May 26-28,
2016, Nizhny Novgorod, Russi
Implementation of a hospital-wide multidisciplinary blunt chest injury care bundle (ChIP): Fidelity of delivery evaluation
BackgroundIneffective intervention for patients with blunt chest wall injury results in high rates of morbidity and mortality. To address this, a blunt chest injury care bundle protocol (ChIP) was developed, and a multifaceted plan was implemented using the Behaviour Change Wheel.ObjectiveThe purpose of this study was to evaluate the reach, fidelity, and dose of the ChIP intervention to discern if it was activated and delivered to patients as intended at two regional Australian hospitals.MethodsThis is a pretest and post-test implementation evaluation study. The proportion of ChIP activations and adherence to ChIP components received by eligible patients were compared before and after intervention over a 4-year period. Sample medians were compared using the nonparametric median test, with 95% confidence intervals. Differences in proportions for categorical data were compared using the two-sample z-test.Results/findingsOver the 19-month postimplementation period, 97.1% (n = 440) of eligible patients received ChIP (reach). The median activation time was 134 min; there was no difference in time to activation between business hours and after-hours; time to activation was not associated with comorbidities and injury severity score. Compared with the preimplementation group, the postimplementation group were more likely to receive evidence-based treatments (dose), including high-flow nasal cannula use (odds ratio [OR] = 6.8 [95% confidence interval {CI} = 4.8-9.6]), incentive spirometry in the emergency department (OR = 7.5, [95% CI = 3.2-17.6]), regular analgesia (OR = 2.4 [95% CI = 1.5-3.8]), regional analgesia (OR = 2.8 [95% CI = 1.5-5.3]), patient-controlled analgesia (OR = 1.8 [95% CI = 1.3-2.4]), and multiple specialist team reviews, e.g., surgical review (OR = 9.9 [95% CI = 6.1-16.1]).ConclusionsHigh fidelity of delivery was achieved and sustained over 19 months for implementation of a complex intervention in the acute context through a robust implementation plan based on theoretical frameworks. There were significant and sustained improvements in care practices known to result in better patient outcomes. Findings from this evaluation can inform future implementation programs such as ChIP and other multidisciplinary interventions in an emergency or acute care context
Imbibition in Disordered Media
The physics of liquids in porous media gives rise to many interesting
phenomena, including imbibition where a viscous fluid displaces a less viscous
one. Here we discuss the theoretical and experimental progress made in recent
years in this field. The emphasis is on an interfacial description, akin to the
focus of a statistical physics approach. Coarse-grained equations of motion
have been recently presented in the literature. These contain terms that take
into account the pertinent features of imbibition: non-locality and the
quenched noise that arises from the random environment, fluctuations of the
fluid flow and capillary forces. The theoretical progress has highlighted the
presence of intrinsic length-scales that invalidate scale invariance often
assumed to be present in kinetic roughening processes such as that of a
two-phase boundary in liquid penetration. Another important fact is that the
macroscopic fluid flow, the kinetic roughening properties, and the effective
noise in the problem are all coupled. Many possible deviations from simple
scaling behaviour exist, and we outline the experimental evidence. Finally,
prospects for further work, both theoretical and experimental, are discussed.Comment: Review article, to appear in Advances in Physics, 53 pages LaTe
GLAST: Understanding the High Energy Gamma-Ray Sky
We discuss the ability of the GLAST Large Area Telescope (LAT) to identify,
resolve, and study the high energy gamma-ray sky. Compared to previous
instruments the telescope will have greatly improved sensitivity and ability to
localize gamma-ray point sources. The ability to resolve the location and
identity of EGRET unidentified sources is described. We summarize the current
knowledge of the high energy gamma-ray sky and discuss the astrophysics of
known and some prospective classes of gamma-ray emitters. In addition, we also
describe the potential of GLAST to resolve old puzzles and to discover new
classes of sources.Comment: To appear in Cosmic Gamma Ray Sources, Kluwer ASSL Series, Edited by
K.S. Cheng and G.E. Romer
Towards Quantum Repeaters with Solid-State Qubits: Spin-Photon Entanglement Generation using Self-Assembled Quantum Dots
In this chapter we review the use of spins in optically-active InAs quantum
dots as the key physical building block for constructing a quantum repeater,
with a particular focus on recent results demonstrating entanglement between a
quantum memory (electron spin qubit) and a flying qubit (polarization- or
frequency-encoded photonic qubit). This is a first step towards demonstrating
entanglement between distant quantum memories (realized with quantum dots),
which in turn is a milestone in the roadmap for building a functional quantum
repeater. We also place this experimental work in context by providing an
overview of quantum repeaters, their potential uses, and the challenges in
implementing them.Comment: 51 pages. Expanded version of a chapter to appear in "Engineering the
Atom-Photon Interaction" (Springer-Verlag, 2015; eds. A. Predojevic and M. W.
Mitchell
Risk propensity in the foreign direct investment location decision of emerging multinationals
A distinguishing feature of emerging economy multinationals is their apparent tolerance for host country institutional risk. Employing behavioral decision theory and quasi-experimental data, we find that managers’ domestic experience satisfaction increases their relative risk propensity regarding controllable risk (legally protectable loss), but decreases their tendency to accept non-controllable risk (e.g., political instability). In contrast, firms’ potential slack reduces relative risk propensity regarding controllable risk, yet amplifies the tendency to take non-controllable risk. We suggest that these counterbalancing effects might help explain observation that risk-taking in FDI location decisions is influenced by firm experience and context. The study provides a new understanding of why firms exhibit heterogeneous responses to host country risks, and the varying effects of institutions
Mind your step: the effects of mobile phone use on gaze behavior in stair climbing
Stair walking is a hazardous activity and a common cause of fatal and non-fatal falls. Previous studies have assessed the role of eye movements in stair walking by asking people to repeatedly go up and down stairs in quiet and controlled conditions, while the role of peripheral vision was examined by giving participants specific fixation instructions or working memory tasks. We here extend this research to stair walking in a natural environment with other people present on the stairs and a now common secondary task: Using one's mobile phone. Results show that using the mobile phone strongly draws one's attention away from the stairs, but that the distribution of gaze locations away from the phone is little influenced by using one's phone. Phone use also increased the time needed to walk the stairs, but handrail use remained low. These results indicate that limited foveal vision suffices for adequate stair walking in normal environments, but that mobile phone use has a strong influence on attention, which may pose problems when unexpected obstacles are encountered
Historical Research Approaches to the Analysis of Internationalisation
Historical research methods and approaches can improve understanding of the most appropriate techniques to confront data and test theories in internationalisation research. A critical analysis of all “texts” (sources), time series analyses, comparative methods across time periods and space, counterfactual analysis and the examination of outliers are shown to have the potential to improve research practices. Examples and applications are shown in these key areas of research with special reference to internationalisation processes. Examination of these methods allows us to see internationalisation processes as a sequenced set of decisions in time and space, path dependent to some extent but subject to managerial discretion. Internationalisation process research can benefit from the use of historical research methods in analysis of sources, production of time-lines, using comparative evidence across time and space and in the examination of feasible alternative choices
An extremely powerful long-lived superluminal ejection from the black hole MAXI J1820+070
Black holes in binary systems execute patterns of outburst activity where two
characteristic X-ray states are associated with different behaviours observed
at radio wavelengths. The hard state is associated with radio emission
indicative of a continuously replenished, collimated, relativistic jet, whereas
the soft state is rarely associated with radio emission, and never
continuously, implying the absence of a quasi-steady jet. Here we report radio
observations of the black hole transient MAXI J1820070 during its 2018
outburst. As the black hole transitioned from the hard to soft state we
observed an isolated radio flare, which, using high angular resolution radio
observations, we connect with the launch of bi-polar relativistic ejecta. This
flare occurs as the radio emission of the core jet is suppressed by a factor of
over 800. We monitor the evolution of the ejecta over 200 days and to a maximum
separation of 10, during which period it remains detectable due to in-situ
particle acceleration. Using simultaneous radio observations sensitive to
different angular scales we calculate an accurate estimate of energy content of
the approaching ejection. This energy estimate is far larger than that derived
from state transition radio flare, suggesting a systematic underestimate of jet
energetics
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