In pursuit of certainty: Can the systematic review process deliver?

Background: There has been increasing emphasis on evidence-based approaches to improve patient outcomes through rigorous, standardised and well-validated approaches. Clinical guidelines drive this process and are largely developed based on the findings of systematic reviews (SRs). This paper presents a discussion of the SR process in providing decisive information to shape and guide clinical practice, using a purpose-built review database: the Cochrane reviews; and focussing on a highly prevalent medical condition: hypertension. Methods. We searched the Cochrane database and identified 25 relevant SRs incorporating 443 clinical trials. Reviews with the terms 'blood pressure' or 'hypertension' in the title were included. Once selected for inclusion, the abstracts were assessed independently by two authors for their capacity to inform and influence clinical decision-making. The inclusions were independently audited by a third author. Results: Of the 25 SRs that formed the sample, 12 provided conclusive findings to inform a particular treatment pathway. The evidence-based approaches offer the promise of assisting clinical decision-making through clarity, but in the case of management of blood pressure, half of the SRs in our sample highlight gaps in evidence and methodological limitations. Thirteen reviews were inconclusive, and eight, including four of the 12 conclusive SRs, noted the lack of adequate reporting of potential adverse effects or incidence of harm. Conclusions: These findings emphasise the importance of distillation, interpretation and synthesis of information to assist clinicians. This study questions the utility of evidence-based approaches as a uni-dimensional approach to improving clinical care and underscores the importance of standardised approaches to include adverse events, incidence of harm, patient's needs and preferences and clinician's expertise and discretion. © 2013 Saltman et al; licensee BioMed Central Ltd

Applications of patching to quadratic forms and central simple algebras

This paper provides applications of patching to quadratic forms and central simple algebras over function fields of curves over henselian valued fields. In particular, we use a patching approach to reprove and generalize a recent result of Parimala and Suresh on the u-invariant of p-adic function fields, for p odd. The strategy relies on a local-global principle for homogeneous spaces for rational algebraic groups, combined with local computations.Comment: 48 pages; connectivity now required in the definition of rational group; beginning of Section 4 reorganized; other minor change

Transportability of tertiary qualifications and CPD: A continuing challenge for the global health workforce

Background: In workforces that are traditionally mobile and have long lead times for new supply, such as health, effective global indicators of tertiary education are increasingly essential. Difficulties with transportability of qualifications and cross-accreditation are now recognised as key barriers to meeting the rapidly shifting international demands for health care providers. The plethora of mixed education and service arrangements poses challenges for employers and regulators, let alone patients; in determining equivalence of training and competency between individuals, institutions and geographical locations. Discussion: This paper outlines the shortfall of the current indicators in assisting the process of global certification and competency recognition in the health care workforce. Using Organisation for Economic Cooperation and Development (OECD) data we highlight how International standardisation in the tertiary education sector is problematic for the global health workforce. Through a series of case studies, we then describe a model which enables institutions to compare themselves internally and with others internationally using bespoke or prioritised parameters rather than standards. Summary: The mobility of the global health workforce means that transportability of qualifications is an increasing area of concern. Valid qualifications based on workplace learning and assessment requires at least some variables to be benchmarked in order to judge performance. © 2012 Saltman et al.; licensee BioMed Central Ltd

Rationality of quotients by linear actions of affine groups

Let G be the (special) affine group, semidirect product of SL_n and C^n. In this paper we study the representation theory of G and in particular the question of rationality for V/G where V is a generically free G-representation. We show that the answer to this question is positive if the dimension of V is sufficiently large and V is indecomposable. We have a more precise theorem if V is a two-step extension 0 -> S -> V -> Q -> 0 with S, Q completely reducible.Comment: 18 pages; dedicated to Fabrizio Catanese on the occasion of his 60th birthda

Open Problems on Central Simple Algebras

We provide a survey of past research and a list of open problems regarding central simple algebras and the Brauer group over a field, intended both for experts and for beginners.Comment: v2 has some small revisions to the text. Some items are re-numbered, compared to v

"Big" Divisor D3/D7 Swiss Cheese Phenomenology

We review progress made over the past couple of years in the field of Swiss Cheese Phenomenology involving a mobile space-time filling D3-brane and stack(s) of fluxed D7-branes wrapping the "big" (as opposed to the "small") divisor in (the orientifold of a) Swiss-Cheese Calabi-Yau. The topics reviewed include reconciliation of large volume cosmology and phenomenology, evaluation of soft supersymmetry breaking parameters, one-loop RG-flow equations' solutions for scalar masses, obtaining fermionic (possibly first two generations' quarks/leptons) mass scales in the O(MeV-GeV)-regime as well as (first two generations') neutrino masses (and their one-loop RG flow) of around an eV. The heavy sparticles and the light fermions indicate the possibility of "split SUSY" large volume scenario.Comment: Invited review for MPLA, 14 pages, LaTe

Stable de Sitter vacua in N=2, D=5 supergravity

We find 5D gauged supergravity theories exhibiting stable de Sitter vacua. These are the first examples of stable de Sitter vacua in higher-dimensional (D>4) supergravity. Non-compact gaugings with tensor multiplets and R-symmetry gauging seem to be the essential ingredients in these models. They are however not sufficient to guarantee stable de Sitter vacua, as we show by investigating several other models. The qualitative behaviour of the potential also seems to depend crucially on the geometry of the scalar manifold.Comment: 26 pages, v2:typos corrected, published versio

Fields of definition for division algebras

Abstract Let A be a finite-dimensional division algebra containing a base field k in its center F. A is defined over a subfield F 0 if there exists an F 0 -algebra A 0 such that A = A 0 F 0 F. The following are shown. (i) In many cases A can be defined over a rational extension of k. (ii) If A has odd degree n > 5, then A is defined over a field F 0 of transcendence degree 6 1 2 (n − 1)(n − 2) over k. (iii) If A is a Z/m × Z/2-crossed product for some m > 2 (and in particular, if A is any algebra of degree 4) then A is Brauer equivalent to a tensor product of two symbol algebras. Consequently, M m (A) can be defined over a field F 0 such that trdeg k (F 0 ) 6 4. (iv) If A has degree 4 then the trace form of A can be defined over a field F 0 of transcendence degree 6 4. (In (i), (iii) and (iv) it is assumed that the center of A contains certain roots of unity.