Constrained variable clustering and the best basis problem in functional data analysis

International audienceFunctional data analysis involves data described by regular functions rather than by a finite number of real valued variables. While some robust data analysis methods can be applied directly to the very high dimensional vectors obtained from a fine grid sampling of functional data, all methods benefit from a prior simplification of the functions that reduces the redundancy induced by the regularity. In this paper we propose to use a clustering approach that targets variables rather than individual to design a piecewise constant representation of a set of functions. The contiguity constraint induced by the functional nature of the variables allows a polynomial complexity algorithm to give the optimal solution

Search for jet extinction in the inclusive jet-pT spectrum from proton-proton collisions at s=8 TeV

Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published articles title, journal citation, and DOI.The first search at the LHC for the extinction of QCD jet production is presented, using data collected with the CMS detector corresponding to an integrated luminosity of 10.7  fb−1 of proton-proton collisions at a center-of-mass energy of 8 TeV. The extinction model studied in this analysis is motivated by the search for signatures of strong gravity at the TeV scale (terascale gravity) and assumes the existence of string couplings in the strong-coupling limit. In this limit, the string model predicts the suppression of all high-transverse-momentum standard model processes, including jet production, beyond a certain energy scale. To test this prediction, the measured transverse-momentum spectrum is compared to the theoretical prediction of the standard model. No significant deficit of events is found at high transverse momentum. A 95% confidence level lower limit of 3.3 TeV is set on the extinction mass scale

Searches for electroweak neutralino and chargino production in channels with Higgs, Z, and W bosons in pp collisions at 8 TeV

Searches for supersymmetry (SUSY) are presented based on the electroweak pair production of neutralinos and charginos, leading to decay channels with Higgs, Z, and W bosons and undetected lightest SUSY particles (LSPs). The data sample corresponds to an integrated luminosity of about 19.5 fb(-1) of proton-proton collisions at a center-of-mass energy of 8 TeV collected in 2012 with the CMS detector at the LHC. The main emphasis is neutralino pair production in which each neutralino decays either to a Higgs boson (h) and an LSP or to a Z boson and an LSP, leading to hh, hZ, and ZZ states with missing transverse energy (E-T(miss)). A second aspect is chargino-neutralino pair production, leading to hW states with E-T(miss). The decays of a Higgs boson to a bottom-quark pair, to a photon pair, and to final states with leptons are considered in conjunction with hadronic and leptonic decay modes of the Z and W bosons. No evidence is found for supersymmetric particles, and 95% confidence level upper limits are evaluated for the respective pair production cross sections and for neutralino and chargino mass values

The Impact of Personal Attitudes on the Growth Ambitions of Small Business Owners

Purpose The purpose of this paper is to provide an empirical evidence in support of widespread calls for new approaches to understanding small business growth, by exploring the use of non-positivist methods (e.g. critical realism) to analyse how owners’ innate dispositions shape growth in practice. Design/methodology/approach In 2014, a telephone survey was used to inform two focus groups and 29 in-depth interviews with small business owners throughout England, covering attitudes towards growth, the use of particular strategies and perceived barriers. Discourse analysis was used to develop a multi-layered explanatory model incorporating key ideas from critical realism and the work of Bourdieu. Findings Bourdieusian analysis reveals the existence of orientations among small business owners towards or against business growth. Such attitudes tend to impact upon their response to perceived barriers. Growth-inclined owners were willing to strategise for long-term benefit, in return for lower returns in the short term. Growth-resistant owners were more likely to view obstacles as absolute, stating that they cannot grow their firms as a result. Practical implications Removing or reducing obstacles may not encourage growth if motivations and attitudes of owners do not change to embrace more growth-oriented positions. Banks’ lending practices, for example, were seen by many as problematic, but growth-oriented owners were more willing to seek and use alternatives to raise funds for growth. Originality/value The authors suggest that entrepreneurship researchers should look beyond positivist research to epistemologies that provide more multi-layered modes of explanation