245 research outputs found
A functional limit theorem for the profile of search trees
We study the profile of random search trees including binary search
trees and -ary search trees. Our main result is a functional limit theorem
of the normalized profile for in a certain range of . A central feature of the proof is the
use of the contraction method to prove convergence in distribution of certain
random analytic functions in a complex domain. This is based on a general
theorem concerning the contraction method for random variables in an
infinite-dimensional Hilbert space. As part of the proof, we show that the
Zolotarev metric is complete for a Hilbert space.Comment: Published in at http://dx.doi.org/10.1214/07-AAP457 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Push and pull escape travel motivations of Emirati nationals to Australia
© 2017, © Emerald Publishing Limited. Purpose: The purpose of this study is to examine the escape motivations of the emerging market and provide suggestions for Australia’s promotion. This study adopts the push and pull framework to identify travel motivations of Emirati nationals to Australia. Design/methodology/approach: This study uses a series of focus groups and in-depth interviews to understand the escape motivations that encourage Emiratis to leave their home country and travel to Australia for a holiday. Findings: The results indicate that Emiratis are motivated to travel to Australia by three escape factors: physical, interpersonal and fun. The internal motivations that encourage Emiratis to escape their home country are inseparable from Australia’s external attributes that attract the Emiratis to the country. Originality/value: The study contributes to the theory of tourist motivation by supporting it in the culturally different Muslim/Arab context, which has not been explored before. The authors argue that it is not so much what Australia offers and what escape needs the Emiratis can fulfil in Australia, but rather that Australia serves the Emiratis well and meets their escape needs
TSP – Infrastructure for the Traveling Salesperson Problem
The traveling salesperson (or, salesman) problem (TSP) is a well known and important combinatorial optimization problem. The goal is to find the shortest tour that visits each city in a given list exactly once and then returns to the starting city. Despite this simple problem statement, solving the TSP is difficult since it belongs to the class of NP-complete problems. The importance of the TSP arises besides from its theoretical appeal from the variety of its applications. Typical applications in operations research include vehicle routing, computer wiring, cutting wallpaper and job sequencing. The main application in statistics is combinatorial data analysis, e.g., reordering rows and columns of data matrices or identifying clusters. In this paper we introduce the R˜package TSP which provides a basic infrastructure for handling and solving the traveling salesperson problem. The package features S3 classes for specifying a TSP and its (possibly optimal) solution as well as several heuristics to find good solutions. In addition, it provides an interface to Concorde, one of the best exact TSP solvers currently available. Keywords:˜combinatorial optimization, traveling salesman problem, R. 1
Decoder side motion vector derivation for inter frame video coding
ABSTRACT In this paper, a decoder side motion vector derivation scheme for inter frame video coding is proposed. Using a template matching algorithm, motion information is derived at the decoder instead of explicitly coding the information into the bitstream. Based on Lagrangian rate-distortion optimisation, the encoder locally signals whether motion derivation or forward motion coding is used. While our method exploits multiple reference pictures for improved prediction performance and bitrate reduction, only a small template matching search range is required. Derived motion information is reused to improve the performance of predictive motion vector coding in subsequent blocks. An efficient conditional signalling scheme for motion derivation in Skip blocks is employed. The motion vector derivation method has been implemented as an extension to H.264/AVC. Simulation results show that a bitrate reduction of up to 10.4 % over H.264/AVC is achieved by the proposed scheme
Motion robust MR fingerprinting scan to image neonates with prenatal opioid exposure
Background: A noninvasive and sensitive imaging tool is needed to assess the
fast-evolving baby brain. However, using MRI to study non-sedated babies faces
roadblocks, including high scan failure rates due to subjects motion and the
lack of quantitative measures for assessing potential developmental delays.
This feasibility study explores whether MR Fingerprinting scans can provide
motion-robust and quantitative brain tissue measurements for non-sedated
infants with prenatal opioid exposure, presenting a viable alternative to
clinical MR scans. Assessment: MRF image quality was compared to pediatric MRI
scans using a fully crossed, multiple reader multiple case study. The
quantitative T1 and T2 values were used to assess brain tissue changes between
babies younger than one month and babies between one and two months.
Statistical Tests: Generalized estimating equations (GEE) model was performed
to test the significant difference of the T1 and T2 values from eight white
matter regions of babies under one month and those are older. MRI and MRF image
quality were assessed using Gwets second order auto-correlation coefficient
(AC2) with its confidence levels. We used the Cochran-Mantel-Haenszel test to
assess the difference in proportions between MRF and MRI for all features and
stratified by the type of features. Results: In infants under one month of age,
the T1 and T2 values are significantly higher (p<0.005) compared to those
between one and two months. A multiple-reader and multiple-case study showed
superior image quality ratings in anatomical features from the MRF images than
the MRI images. Conclusions: This study suggested that the MR Fingerprinting
scans offer a motion-robust and efficient method for non-sedated infants,
delivering superior image quality than clinical MRI scans and additionally
providing quantitative measures to assess brain development
The Resource Curse and Rentier States in the Caspian Region : A Need for Context Analysis
Although much attention is paid to the Caspian region with regard to energy issues, the domestic
consequences of the region’s resource production have so far constituted a neglected field of research.
A systematic survey of the latest research trends in the economic and political causalities of
the resource curse and of rentier states reveals that there is a need for context analysis. In reference
to this, the paper traces any shortcomings and promising approaches in the existent body of literature
on the Caspian region. Following on from this, the paper then proposes a new approach; specifically,
one in which any differences and similarities in the context conditions are captured. This
enables a more precise exploration of the exact ways in which they form contemporary post-Soviet
Caspian rentier states.Obwohl der Region am Kaspischen Meer im Zuge von Energiediskursen große Aufmerksamkeit zuteil
wird, stellen die innerstaatlichen Folgen der Ressourcenproduktion in der Region ein bislang
vernachlässigtes Forschungsfeld dar. Ein systematischer Überblick über die jüngsten Forschungstrends
zu wirtschaftlichen und politischen Kausalzusammenhängen des Ressourcenfluchs und zu
Rentierstaaten offenbart die Notwendigkeit von Kontextanalysen. Hierauf Bezug nehmend, analysiert
der Aufsatz sowohl die Mängel als auch viel versprechende Ansätze in der betreffenden Literatur
zur Region am Kaspischen Meer. Der Aufsatz stellt letztendlich einen neuen Ansatz vor, der
Unterschiede und Gemeinsamkeiten in den Kontextbedingungen erfasst, um zu erforschen, wie diese
die gegenwärtigen post-sowjetischen Rentierstaaten in der Region am Kaspischen Meer tatsächlich
prägen
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