Verification of the standard model of the photorefractive nonlinearity in BSO crystals

On the basis of the standard model for the photorefractive nonlinearity we investigate whether a systematic description of the dependence of two-beam energy exchange on beam polarization and grating vector K is possible. Our result is that there is good agreement between theory and experiment with respect to the polarization properties and semi-quantitative agreement with respect to the K-dependence of the energy exchange.

Non-standard techniques for the investigation of the visual field

The study investigated the potential applications and the limitations of non-standard techniques of visual field investigation utilizing automated perimetry. Normal subjects exhibited a greater sensitivity to kinetic stimuli than to static stimuli of identical size. The magnitude of physiological SKD was found to be largely independent of age, stimulus size, meridian and eccentricity. The absence of a dependency on stimulus size indicated that successive lateral spatial summation could not totally account for the underlying mechanism of physiological SKD. The visual field indices MD and LV exhibited a progressive deterioration during the time course of a conventional central visual field examination both for normal subjects and for ocular hypertensive patients. The fatigue effect was more pronounced in the latter stages and for the second eye tested. The confidence limits for the definition of abnormality should reflect the greater effect of fatigue on the second eye. A 330 cdm-2 yellow background was employed for blue-on-yellow perimetry. Instrument measurement range was preserved by positioning a concave mirror behind the stimulus bulb to increase the light output by 60% . The mean magnitude of SWS pathway isolation was approximately 1.4 log units relative to a 460nm stimulus filter. The absorption spectra of the ocular media exhibited an exponential increase with increase in age, whilst that of the macular pigment showed no systematic trend. The magnitude of ocular media absorption was demonstrated to reduce with increase in wavelength. Ocular media absorption was significantly greater in diabetic patients than in normal subjects. Five diabetic patients with either normal or borderline achromatic sensitivity exhibited an abnormal blue-on-yellow sensitivity; two of these patients showed no signs of retinopathy. A greater vulnerability of the SWS pathway to the diabetic disease process was hypothesized.

Verification of the standard model of the photorefractive nonlinearity in BSO crystals

On the basis of the standard model for the photorefractive nonlinearity we investigate whether a systematic description of the dependence of two-beam energy exchange on beam polarization and grating vector K is possible. Our result is that there is good agreement between theory and experiment with respect to the polarization properties and semi-quantitative agreement with respect to the K-dependence of the energy exchange.

Enhanced Raman amplifier flatness with nonlinear broadening over non-standard transmission fibre

Nonlinear CW pump broadening over non-standard transmission fibre is used for the first time to achieve improved gain flatness in a single-pump broadband Raman amplifier. As an illustration of the benefits that can be obtained from this approach, a threefold increase in the bandwidth for 0.1 dB gain variation is reported when the broadened pump is used to produce 9.2 dB on-off gain over 25 km LEAF fibre. © 2005 Elsevier B.V. All rights reserved.

*ZFC : une nouvelle approche axiomatique à l'analyse non-standard

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

*ZFC : une nouvelle approche axiomatique à l'analyse non-standard

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Key determinants of organisational silence for non-standard workers

Purpose – The purpose of this paper is to identify the key determinants of organisational silence from the perspective of non-standard workers (NSWs). The study focuses on three research themes: first, analysing the experiences motivating NSWs to remain silent; second, analysing the role of the NSW life cycle in the motivation to remain silent, the final theme is evaluation of the impact on organisational voice of an organisation employing a workforce in which NSWs and standard workers (SWs) are blended. Design/methodology/approach – The study utilises a phenomenological approach, as defined by Van Manen (2007), to collect and analyse the phenomenon of organisational silence from the perspective of NSWs. The NSWs are defined as individuals operating via Limited Liability UK registered companies created for the purpose of delivering services to organisations via a contract of services. This study employed a combination of phenomenology and hermeneutics to collect and analyse the data collected from the NSWs using semi-structured interviews (Lindseth and Norberg, 2004). Findings – The study concludes with three core findings. NSWs experience similar motivational factors to silence as experienced by standard workers (SWs). The key differential between a SW and a NSW is the role of defensive silence as a dominant motivator for a start-up NSW. The study identified that the reasons for this is that new NSWs are defensive to protect their reputation for any future contract opportunities. In addition, organisations are utilising the low confidence of new start up NSWs to suppress the ability of NSWs to voice. The research indicates how experienced NSWs use the marketing stage of their life cycle to establish voice mechanisms. The study identified that NSWs, fulfiling management and supervisory roles for organisations, are supporting/creating climates of silence through their transfer of experiences as SWs prior to becoming NSWs. Research limitations/implications – This study is a pilot study, and the findings from this study will be carried forward into a larger scale study through engagement with further participants across a diverse range of sectors. This study has identified that there is a need for further studies on organisational silence and NSWs to analyse more fully the impact of silence on the individuals and the organisation itself. A qualitative phenomenological hermeneutical study is not intended to be extrapolated to provide broad trends. The focus of the phenomenological hermeneutic research methodology is on describing and analysing the richness and depth of the NSW’s experiences of silence in organisational settings. Originality/value – This paper draws together the studies of worker classification, motivators for organisational silence, and the impact of blending SWs and NSWs in an organisational setting. The study demonstrates that academic research to date has focused predominantly on SWs to the exclusion of the 1.5 million, and growing, NSWs in the UK. This study examines these under-represented workers to analyse the participants’ experiences of organisational silence, and its consequences in organisational settings, demonstrating a need for further studies.

Higgs production in association with top quarks at the LHC

Since it has been found that the MadGraph Monte Carlo generator offers superior flavour-matching capability as compared to Alpgen, the suitability of MadGraph for the generation of ttb¯ ¯b events is explored, with a view to simulating this background in searches for the Standard Model Higgs production and decay process ttH, H ¯ → b ¯b. Comparisons are performed between the output of MadGraph and that of Alpgen, showing that satisfactory agreement in their predictions can be obtained with the appropriate generator settings. A search for the Standard Model Higgs boson, produced in association with the top quark and decaying into a b ¯b pair, using 20.3 fb−1 of 8 TeV collision data collected in 2012 by the ATLAS experiment at CERN’s Large Hadron Collider, is presented. The GlaNtp analysis framework, together with the RooFit package and associated software, are used to obtain an expected 95% confidence-level limit of 4.2 +4.1 −2.0 times the Standard Model expectation, and the corresponding observed limit is found to be 5.9; this is within experimental uncertainty of the published result of the analysis performed by the ATLAS collaboration. A search for a heavy charged Higgs boson of mass mH± in the range 200 ≤ mH± /GeV ≤ 600, where the Higgs mediates the five-flavour beyond-theStandard-Model physics process gb → tH± → ttb, with one top quark decaying leptonically and the other decaying hadronically, is presented, using the 20.3 fb−1 8 TeV ATLAS data set. Upper limits on the product of the production cross-section and the branching ratio of the H± boson are computed for six mass points, and these are found to be compatible within experimental uncertainty with those obtained by the corresponding published ATLAS analysis.

All one-loop scalar vertices in the effective potential approach

Using the one-loop Coleman-Weinberg effective potential, we derive a general analytic expression for all the derivatives of the effective potential with respect to any number of classical scalar fields. The result is valid for a renormalisable theory in four dimensions with any number of scalars, fermions or gauge bosons. This result corresponds to the zero-external momentum contribution to a general one-loop diagram with N scalar external legs. We illustrate the use of the general result in two simple scalar singlet extensions of the Standard Model, to obtain the dominant contributions to the triple couplings of light scalar particles under the zero external momentum approximation.

Assessment of non-standard HIV antiretroviral therapy regimens at Lighthouse Trust in Lilongwe, Malawi

Aim: Lighthouse Trust in Lilongwe, Malawi serves approximately 25,000 patients with HIV antiretroviral therapy (ART) regimens standardized according to national treatment guidelines. However, as a referral centre for complex cases, Lighthouse Trust occasionally treats patients with non-standard ART regimens (NS-ART) that deviate from the treatment guidelines. We evaluated factors contributing to the use of NS-ART and whether patients could transition to standard regimens. Methods: This was a cross-sectional study of all adult patients at Lighthouse Trust being treated with NS-ART as of February 2012. Patients were identified using the electronic data system. Medical charts were reviewed and descriptive statistics were obtained. Results: One hundred six patients were initially found being treated with NS-ART, and 92 adult patients were confirmed to be on NS-ART after review. Mean patient age was 42.4 ± 10.3 years, and 52 (57%) were female. Mean duration of treatment with the NS-ART being used at the time of data collection was 2.1 ± 1.5 years. Eight patients (9%) were on modified first-line NS-ART and 84 (91%) were on modified second-line NS-ART, with 90 patients (98%) having multiple factors contributing to NS-ART use. Severe toxicity from one medication contributed in 28 cases (30%) and toxicity from multiple medications contributed in 46 cases (50%), while 22 patients (24%) were transitioned to NS-ART following a stockout of their original medication. Following clinical review, 84 patients (91%) were transitioned to standard regimens, and eight (9%) were maintained on NS-ART because of incompatibility of their clinical features with the latest national guidelines. Conclusions: Primary factors contributing to NS-ART use were medication toxicities and medication stockouts. Most patients were transitioned to standard regimens, although the need for NS-ART remains.

Technicolor

In technicolor theories the scalar sector of the Standard Model is replaced by a strongly interacting sector. Although the Standard Model has been exceptionally successful, the scalar sector causes theoretical problems that make these theories seem an attractive alternative. I begin my thesis by considering QCD, which is the known example of strong interactions. The theory exhibits two phenomena: confinement and chiral symmetry breaking. I find the low-energy dynamics to be similar to that of the sigma models. Then I analyze the problems of the Standard Model Higgs sector, mainly the unnaturalness and triviality. Motivated by the example of QCD, I introduce the minimal technicolor model to resolve these problems. I demonstrate the minimal model to be free of anomalies and then deduce the main elements of its low-energy particle spectrum. I find the particle spectrum contains massless or very light technipions, and also technibaryons and techni-vector mesons with a high mass of over 1 TeV. Standard Model fermions remain strictly massless at this stage. Thus I introduce the technicolor companion theory of flavor, called extended technicolor. I show that the Standard Model fermions and technihadrons receive masses, but that they remain too light. I also discuss flavor-changing neutral currents and precision electroweak measurements. I then show that walking technicolor models partly solve these problems. In these models, contrary to QCD, the coupling evolves slowly over a large energy scale. This behavior adds to the masses so that even the light technihadrons are too heavy to be detected at current particle accelerators. Also all observed masses of the Standard Model particles can be generated, except for the bottom and top quarks. Thus it is shown in this thesis that, excluding the masses of third generation quarks, theories based on walking technicolor can in principle produce the observed particle spectrum.

Search for Top-Quark Production via Flavor-Changing Neutral Currents in W+1 Jet Events at CDF

We report on the first search for top-quark production via flavor-changing neutral-current (FCNC) interactions in the non-standard-model process u(c)+g -> t using ppbar collision data collected by the CDF II detector. The data set corresponds to an integrated luminosity of 2.2/fb. The candidate events feature the signature of semileptonic top-quark decays and are classified as signal-like or background-like by an artificial neural network trained on simulated events. The observed discriminant distribution is in good agreement with the one predicted by the standard model and provides no evidence for FCNC top-quark production, resulting in a Bayesian upper limit on the production cross section sigma (u(c)+g -> t) u+g) c+g)

Search for Anomalous Production of Events with a Photon, Jet, b-quark Jet, and Missing Transverse Energy

We present a signature-based search for anomalous production of events containing a photon, two jets, of which at least one is identified as originating from a b quark, and missing transverse energy. The search uses data corresponding to 2.0/fb of integrated luminosity from p-pbar collisions at a center-of-mass energy of sqrt(s)=1.96 TeV, collected with the CDF II detector at the Fermilab Tevatron. From 6,697,466 events with a photon candidate with transverse energy ET> 25 GeV, we find 617 events with missing transverse energy > 25 GeV and two or more jets with ET> 15 GeV, at least one identified as originating from a b quark, versus an expectation of 607+- 113 events. Increasing the requirement on missing transverse energy to 50 GeV, we find 28 events versus an expectation of 30+-11 events. We find no indications of non-standard-model phenomena.