Casimir bag energy in the stochastic approximation to the pure QCD vacuum

We study the Casimir contribution to the bag energy coming from gluon field fluctuations, within the context of the stochastic vacuum model (SVM) of pure QCD. After formulating the problem in terms of the generating functional of field strength cumulants, we argue that the resulting predictions about the Casimir energy are compatible with the phenomenologically required bag energy term.Comment: 16 page

SUPPORT Tools for evidence-informed health Policymaking (STP)

This article is the Introduction to a series written for people responsible for making decisions about health policies and programmes and for those who support these decision makers

Large Dual Transformations and the Petrov-Diakonov Representation of the Wilson Loop

In this work, based on the Petrov-Diakonov representation of the Wilson loop average W in the SU(2) Yang-Mills theory, together with the Cho-Fadeev-Niemi decomposition, we present a natural framework to discuss possible ideas underlying confinement and ensembles of defects in the continuum. In this language we show how for different ensembles the surface appearing in the Wess-Zumino term in W can be either decoupled or turned into a variable, to be summed together with gauge fields, defects and dual fields. This is discussed in terms of the regularity properties imposed by the ensembles on the dual fields, thus precluding or enabling the possibility of performing the large dual transformations that would be necessary to decouple the initial surface.Comment: 35 pages, LaTeX, corrected version, accepted for publication in Phys. Rev.

Improving the use of research evidence in guideline development: 1. Guidelines for guidelines

BACKGROUND: The World Health Organization (WHO), like many other organisations around the world, has recognised the need to use more rigorous processes to ensure that health care recommendations are informed by the best available research evidence. This is the first of a series of 16 reviews that have been prepared as background for advice from the WHO Advisory Committee on Health Research to WHO on how to achieve this. OBJECTIVES: We reviewed the literature on guidelines for the development of guidelines. METHODS: We searched PubMed and three databases of methodological studies for existing systematic reviews and relevant methodological research. We did not conduct systematic reviews ourselves. Our conclusions are based on the available evidence, consideration of what WHO and other organisations are doing and logical arguments. KEY QUESTIONS AND ANSWERS: We found no experimental research that compared different formats of guidelines for guidelines or studies that compared different components of guidelines for guidelines. However, there are many examples, surveys and other observational studies that compared the impact of different guideline development documents on guideline quality. WHAT HAVE OTHER ORGANIZATIONS DONE TO DEVELOP GUIDELINES FOR GUIDELINES FROM WHICH WHO CAN LEARN? • Establish a credible, independent committee that evaluates existing methods for developing guidelines or that updates existing ones. • Obtain feedback and approval from various stakeholders during the development process of guidelines for guidelines. • Develop a detailed source document (manual) that guideline developers can use as reference material. WHAT SHOULD BE THE KEY COMPONENTS OF WHO GUIDELINES FOR GUIDELINES? • Guidelines for guidelines should include information and instructions about the following components: 1) Priority setting; 2) Group composition and consultations; 3) Declaration and avoidance of conflicts of interest; 4) Group processes; 5) Identification of important outcomes; 6) Explicit definition of the questions and eligibility criteria ; 7) Type of study designs for different questions; 8) Identification of evidence; 9) Synthesis and presentation of evidence; 10) Specification and integration of values; 11) Making judgments about desirable and undesirable effects; 12) Taking account of equity; 13) Grading evidence and recommendations; 14) Taking account of costs; 15) Adaptation, applicability, transferability of guidelines; 16) Structure of reports; 17) Methods of peer review; 18) Planned methods of dissemination & implementation; 19) Evaluation of the guidelines. WHAT HAVE OTHER ORGANIZATIONS DONE TO IMPLEMENT GUIDELINES FOR GUIDELINES FROM WHICH WHO CAN LEARN? • Obtain buy-in from regions and country level representatives for guidelines for guidelines before dissemination of a revised version. • Disseminate the guidelines for guidelines widely and make them available (e.g. on the Internet). • Develop examples of guidelines that guideline developers can use as models when applying the guidelines for guidelines. • Ensure training sessions for those responsible for developing guidelines. • Continue to monitor the methodological literature on guideline development

Improving the use of research evidence in guideline development: introduction

In 2005 the World Health Organisation (WHO) asked its Advisory Committee on Health Research (ACHR) for advice on ways in which WHO can improve the use of research evidence in the development of recommendations, including guidelines and policies. The ACHR established the Subcommittee on the Use of Research Evidence (SURE) to collect background documentation and consult widely among WHO staff, international experts and end users of WHO recommendations to inform its advice to WHO. We have prepared a series of reviews of methods that are used in the development of guidelines as part of this background documentation. We describe here the background and methods of these reviews, which are being published in Health Research Policy and Systems together with this introduction

Single Superfield Representation for Mixed Retarded and Advanced Correlators in Disordered Systems

We propose a new single superfield representation for mixed retarded and advanced correlators for noninteracting disordered systems. The method is tested in the simpler context of Random Matrix theory, by comparing with well known universal behavior for level spacing correlations. Our method is general and could be especially interesting to study localization properties encoded in the mixed correlators of Quantum Hall systems.Comment: 13 pages including two figures, RevTex4. Improved version. Figures changed. To appear in Journal of Physics

Non-perturbative behavior of the quantum phase transition to a nematic Fermi fluid

We discuss shape (Pomeranchuk) instabilities of the Fermi surface of a two-dimensional Fermi system using bosonization. We consider in detail the quantum critical behavior of the transition of a two dimensional Fermi fluid to a nematic state which breaks spontaneously the rotational invariance of the Fermi liquid. We show that higher dimensional bosonization reproduces the quantum critical behavior expected from the Hertz-Millis analysis, and verify that this theory has dynamic critical exponent $z=3$. Going beyond this framework, we study the behavior of the fermion degrees of freedom directly, and show that at quantum criticality as well as in the the quantum nematic phase (except along a set of measure zero of symmetry-dictated directions) the quasi-particles of the normal Fermi liquid are generally wiped out. Instead, they exhibit short ranged spatial correlations that decay faster than any power-law, with the law $|x|^{-1} \exp(-\textrm{const.} |x|^{1/3})$ and we verify explicitely the vanishing of the fermion residue utilizing this expression. In contrast, the fermion auto-correlation function has the behavior $|t|^{-1} \exp(-{\rm const}. |t|^{-2/3})$. In this regime we also find that, at low frequency, the single-particle fermion density-of-states behaves as $N^*(\omega)=N^*(0)+ B \omega^{2/3} \log\omega +...$, where $N^*(0)$ is larger than the free Fermi value, N(0), and $B$ is a constant. These results confirm the non-Fermi liquid nature of both the quantum critical theory and of the nematic phase.Comment: 20 pages, 2 figures, 1 table; new version with minor changes; new subsection 3C2 added with an explicit calculation of the quasiparticle residue at the nematic transition; minor typos corrected, new references; general beautification of the text and figure

Improving the use of research evidence in guideline development: 13. Applicability, transferability and adaptation

BACKGROUND: The World Health Organization (WHO), like many other organisations around the world, has recognised the need to use more rigorous processes to ensure that health care recommendations are informed by the best available research evidence. This is the thirteenth of a series of 16 reviews that have been prepared as background for advice from the WHO Advisory Committee on Health Research to WHO on how to achieve this. OBJECTIVES: We reviewed the literature on applicability, transferability, and adaptation of guidelines. METHODS: We searched five databases for existing systematic reviews and relevant primary methodological research. We reviewed the titles of all citations and retrieved abstracts and full text articles if the citations appeared relevant to the topic. We checked the reference lists of articles relevant to the questions and used snowballing as a technique to obtain additional information. We used the definition "coming from, concerning or belonging to at least two or all nations" for the term international. Our conclusions are based on the available evidence, consideration of what WHO and other organisations are doing and logical arguments. KEY QUESTIONS AND ANSWERS: We did not identify systematic reviews addressing the key questions. We found individual studies and projects published in the peer reviewed literature and on the Internet. Should WHO develop international recommendations? • Resources for developing high quality recommendations are limited. Internationally developed recommendations can facilitate access to and pooling of resources, reduce unnecessary duplication, and involve international scientists. • Priority should be given to international health problems and problems that are important in low and middle-income countries, where these advantages are likely to be greatest. • Factors that influence the transferability of recommendations across different settings should be considered systematically and flagged, including modifying factors, important variation in needs, values, costs and the availability of resources. What should be done centrally and locally? • The preparation of systematic reviews and evidence profiles should be coordinated centrally, in collaboration with organizations that produce systematic reviews. Centrally developed evidence profiles should be adaptable to specific local circumstances. • Consideration should be given to models that involve central coordination with work being undertaken by centres located throughout the world. • While needs, availability of resources, costs, the presence of modifying factors and values need to be assessed locally, support for undertaking these assessments may be needed to make guidelines applicable. • WHO should provide local support for adapting and implementing recommendations by developing tools, building capacity, learning from international experience, and through international networks that support evidence-informed health policies, such as the Evidence-informed Policy Network (EVIPNet). How should recommendations be adapted? • WHO should provide detailed guidance for adaptation of international recommendations. • Local adaptation processes should be systematic and transparent, they should involve stakeholders, and they should report the key factors that influence decisions, including those flagged in international guidelines, and the reasons for any modifications that are made

Effekt av tiltak for implementering av kliniske retningslinjer

Faglige retningslinjer skal bidra til kvalitetsforbedring, til å redu-sere uheldig variasjon i praksis, og til å begrense unødig eller feil bruk av ressurser. Helsedirektoratet har ansvar for å utarbeide og bidra til implementering av retningslinjer. Denne rapporten oppsummerer forskningsresultater om effekt av tiltak rettet mot helsepersonell, for implementering av faglige retningslinjer. Resultater fra systematiske oversikter viser at: • Tiltak som elektronisk beslutningsstøtte, kurs og møter, praksisbesøk, monitorering med tilbakemelding («audit & feedback») og skreddersydde tiltak for implementering av retningslinjer er sannsynligvis effektive, men - effektene varierer - effekten på klinisk praksis er oftest moderat - de forventede effektene på pasientenes helseutfall er beskjedne • For andre tiltak varierer resultatene mye på tvers av de forskjellige studiene. Det er vanskelig å forklare denne variasjonen. Dermed er det usikkert hvor stor gevinst vi kan forvente av å benytte disse tiltakene for implementering av retningslinjer. • For noen tiltak, som bruk av økonomiske insentiver og offentliggjøring av kvalitetsindikatorer, fant vi mangefull dokumentasjon. Følgelig kan vi ikke si så mye om hvor effektive de er

SUPPORT Tools for evidence-informed health Policymaking (STP) 5: Using research evidence to frame options to address a problem

This article is part of a series written for people responsible for making decisions about health policies and programmes and for those who support these decision makers