Quantum Fields as Operator Valued Distributions and Causality

Quantum Field Theory with fields as Operator Valued Distributions with adequate test functions, -the basis of Epstein-Glaser approach known now as Causal Perturbation Theory-, is recalled. Its recent revival is due to new developments in understanding its renormalization structure, which was a major and somehow fatal disease to its widespread use in the seventies. In keeping with the usual way of definition of integrals of differential forms, fields are defined through integrals over the whole manifold, which are given an atlas-independent meaning with the help of the partition of unity. Using such partition of unity test functions turns out to be the key to the fulfilment of the Poincar\'e commutator algebra as well as to provide a direct Lorentz invariant scheme to the Epstein-Glaser extension procedure of singular distributions. These test functions also simplify the analysis of QFT behaviour both in the UV and IR domains, leaving only a finite renormalization at a point related to the arbitrary scale present in the test functions. Some well known UV and IR cases are examplified. Finally the possible implementation of Epstein-Glaser approach in light-front field theory is discussed, focussing on the intrinsic non-pertubative character of the initial light-cone interaction Hamiltonian and on the expected benefits of a divergence-free procedure with only finite RG-analysis on physical observables in the end.Comment: 20 pages,2 figure

QED Fermi-Fields as Operator Valued Distributions and Anomalies

The treatment of fields as operator valued distributions (OPVD) is recalled with the emphasis on the importance of causality following the work of Epstein and Glaser. Gauge invariant theories demand the extension of the usual translation operation on OPVD, thereby leading to a generalized $QED$ formulation. At D=2 the solvability of the Schwinger model is totally preserved. At D=4 the paracompactness property of the Euclidean manifold permits using test functions which are decomposition of unity and thereby provides a natural justification and extension of the non perturbative heat kernel method (Fujikawa) for abelian anomalies. On the Minkowski manifold the specific role of causality in the restauration of gauge invariance (and mass generation for $QED_{2}$) is examplified in a simple way.Comment: soumis le 22/09/200

Aspects of fine-tuning of the Higgs mass within finite field theories

We reanalyze the perturbative radiative corrections to the Higgs mass within the Standard Model in the light of the Taylor-Lagrange renormalization scheme. This scheme naturally leads to completely finite corrections, depending on an arbitrary scale. The formulation avoids very large individual corrections to the Higgs mass. This illustrates the fact that the so-called fine-tuning problem in the Standard Model is just an artifact of the regularization scheme. It should therefore not lead to any physical interpretation in terms of the energy scale at which new physics should show up, nor in terms of a new symmetry. We analyze the intrinsic physical scales relevant for the description of these radiative corrections.Comment: 9 pages. arXiv admin note: substantial text overlap with arXiv:1011.174

Consumption Externalities and Diffusion in Pharmaceutical Markets: Antiulcer Drugs

We examine the role of consumption externalities in the demand for pharmaceuticals at both the brand level and over a therapeutic class of drugs. These effects emerge when use of a drug by others affects its value, and/or conveys information abut efficacy and safety to patients and physicians. This can affect that rate of market diffusion for a new entrant, and can lead to herb behavior whereby a particular drug can dominate the market despite the availability of close substitutes. We use data for H2-antagonist antiulcer drugs to estimate a dynamic demand model and quantify these effects. The model has three components: an hedonic price equation that measures how the aggregate usage of a drug, as well as conventional attributes, affect brand valuation; equations relating equilibrium market shares to quality-adjusted prices and marketing levels; and diffusion equations describing the dynamic adjustment process. We find that consumption externalities influence both valuations and rates of diffusion, but that they operate at the brand and not the therapeutic class level.

European Financial Markets After EMU: A First Assessment

This paper reviews the first evidence on the impact of European Monetary Union on European capital markets, one year after the launch of the single currency. Our assessment of this evidence is very favourable. On almost all counts EMU has either changed the European financial landscape already drastically or has the potential to do so in the future. We argue that this is less due to the well-known direct effects of EMU, such as the elimination of intra-European currency risk, than to a number of indirect consequences through feedback mechanisms that seem to have been triggered by EMU.European Monetary Union; european capital markets

European Financial Markets After EMU: A First Assessment

This paper reviews the first evidence on the impact of European Monetary Union on European capital markets, one year after the launch of the single currency. Our assessment of this evidence is very favourable. On almost all counts EMU has either changed the European financial landscape already drastically or has the potential to do so in the future. We argue that this is less due to the well-known direct effects of EMU, such as the elimination of intra-European currency risk, than to a number of indirect consequences through feedback mechanisms that seem to have been triggered by EMU.

Mega trials in COPD - clinical data analysis and design issues

Randomizowane, kontrolowane badania nad lekami TORCH i UPLIFT dostarczyły istotnych informacji o korzyściach z ich stosowania u chorych na POChP, a także były lekcją dotyczącą wpływu planowania badań i analizy wyników na jakość uzyskanych wyników. Celem badania TORCH było porównanie stosowanego leczenia z leczeniem rutynowym, jednakże grupa placebo nie otrzymywała rutynowego leczenia. TORCH i UPLIFT były jednymi z pierwszych badań, w których analiza wyników oparta była na zasadzie "intention-to-treat", bardzo ważnej dla uniknięcia wątpliwości w badaniach randomizowanych. Jednakże ta zasada obejmowała tylko analizę umieralności, ale już nie czynności płuc. Z tego powodu ta druga ulegała wpływowi zjawiska regresji do średniej. Natomiast dodatkowa analiza wyników badania TORCH wykazała, że korzystny wpływ na umieralność był spowodowany wyłącznie długodziałającym lekiem rozszerzającym oskrzela bez wpływu na obniżenie umieralności na POChP wziewnego steroidu w leczeniu skojarzonym. Łącznie, wyniki tych badań sugerują, że obniżenie umieralności na POChP jest związane z długodziałającymi lekami rozszerzającymi oskrzela, w tym antycholinergikami, takimi jak tiotropium i agonistami receptorów beta, a nie z działaniem wziewnych kortykosteroidów. Przewlekła obturacyjna choroba płuc jest jedną z głównych przyczyn chorobowości i umieralności na świecie. Wielkie badania kliniczne, takie jak TORCH i UPLIFT, są potrzebne, ale powinny być prowadzone z najwyższą naukową starannością w planowaniu i analizie wyników. Pneumonol. Alergol. Pol. 2011; 79, 3: 227-231The TORCH and UPLIFT randomised controlled trials have provided important data on the benefits of COPD treatments, but also some lessons in study design and data analysis that we will here review. Firstly, it is fundamental that the study question be answerable by the study design. The question in the TORCH study was aimed at a comparison with ‘usual care’, but the placebo group was not ‘usual care’. Secondly, TORCH and UPLIFT were among the first trials to follow the intent-to-treat principle, fundamental to avoid bias in randomised trials. However, this principle was followed for the mortality outcome, but not for lung function, so that the findings related to lung function decline are subject to bias from regression to the mean. Finally, a re-analysis of the TORCH study (performed to fully exploit the data as a 2 × 2 factorial trial) shows that a mortality benefit is entirely accounted for by the effect of the long-acting beta-agonist salmeterol, with no effect attributable to the inhaled corticosteroid fluticasone component of the combination therapy. Together, these data suggest that long-acting bronchodilators, including anticholinergics such as tiotropium and beta-agonists, are associated with lower mortality of patients with COPD, but not inhaled corticosteroids. With COPD one of the major causes of morbidity and mortality worldwide, mega trials such as TORCH and UPLIFT are much needed, but must achieve the utmost scientific rigour in their design and analysis. Pneumonol. Alergol. Pol. 2011; 79, 3: 227-23

Impacts of Patent Expiry and Regulatory Policies on Daily Cost of Pharmaceutical Treatments: OECD Countries, 2004-2010

Cross-country variability in regulatory frameworks, industrial policy, physician/pharmacy autonomy, brand/generic distinctions, and in the practice of medicine contributes to ambiguous interpretations of pharmaceutical cost comparisons. Here we report cross-country comparisons that: (i) focus on 11 therapeutic classes experiencing patent expiration and loss of exclusivity 2004-2010 in eight industrialized countries; (ii) convert revenues and unit sales to cost per day of treatment and number patient days treated using the World Health Organizations’ Defined Daily Dosage metrics; (iii) compare patterns in costs per day of treatment with price index measures based on average price per day of treatment for each molecule computed over all molecule versions; (iv) utilizing econometric methods, model and quantify various factors affecting variations in daily treatment price indexes such as national regulatory and reimbursement policy changes, physician/pharmacy autonomy, and other factors; and (v) simulate changes in expenditures by country and therapeutic class had counterfactual policies been implemented