52 research outputs found
Practitioner research in education:A call for a reality check
Practitioner research is often promoted in education for different purposes, usually with the aim of fostering practitioners’ professional development while supporting their identity as practitioner-researchers. Within this landscape, teachers and academics sometimes work together to engage in different forms of collaborative practitioner research. Such endeavours, however, may generate some ethical issues among the academics involved. In this article, we, two university-based academics, reflect on methodological insights by discussing two ethical dilemmas about practitioner research resulting from recent situations: (1) transparency in designing, promoting, doing, and reporting on practitioner research, and (2) the potential co-option of practitioner research initiatives and outcomes. Qua duoethnographic research, this reflective piece adopts an epistolary technique as the shape of the article as it consists of a series of emails exchanged between the authors over a period of time. In so doing, we aim for transparency about how our insights around the ethical issues identified developed organically through written interaction. We concur that it is time for a reality check disposition to disrupt hegemonic onto-epistemic discourses which characterize the ecology of practitioner inquiry
Perturbative higher-derivative terms in N=6 asymmetric orbifolds
We analyse the perturbative four-point amplitudes in the simplest string
theory examples of T-fold backgrounds, which enjoy N=6 supersymmetries in four
dimensions. There are two theories defined as asymmetric orbifolds of order 2
and 3, respectively. The perturbative spectrum and the one-loop four-point
amplitudes are shown to be invariant under an arithmetic symplectic group
defined over the Hurwitz (respectively Eisenstein) quaternions. The
supersymmetry constraints on the low energy effective couplings are determined
and we conjecture the U-duality group of the theory and the non-perturbative
completion of the six-derivative coupling as a rank one theta series. We
discuss the non-perturbative spectrum of BPS states in the light of our
analysis.Comment: 60+37 page
On the N-pion extension of the Lovelace-Shapiro model
We reconsider a modification of the N-point amplitude of the Neveu-Schwarz
(NS) model in which the tachyon becomes a pion by shifting its mass to zero and
keeping the super-projective invariance of the integrand of the amplitude. For
the scattering of four particles it reduces to the amplitude written by
Lovelace and Shapiro that has Adler zeroes. We confirm that also the N-pion
amplitude has Adler zeroes and show that it reduces to that of the non-linear
-model for keeping fixed. The four- and
six-point flavour-ordered amplitudes satisfy tree-level unitarity since they
can be derived from the correspondent amplitudes of the NS model in ten
dimensions by suitably choosing the components of the momenta of the external
mesons in the six extra dimensions. Negative norm states (ghosts) are shown to
appear instead in higher-point amplitudes. We also discuss several amplitudes
involving different external mesons.Comment: 21 pages plus appendices and 1 figur
The multipolar structure of fuzzballs
We extend and refine a general method to extract the multipole moments of
arbitrary stationary spacetimes and apply it to the study of a large family of
regular horizonless solutions to four-dimensional
supergravity coupled to four Abelian gauge fields. These microstate geometries
can carry angular momentum and have a much richer multipolar structure than the
Kerr black hole. In particular they break the axial and equatorial symmetry,
giving rise to a large number of nontrivial multipole moments. After studying
some analytical examples, we explore the four-dimensional parameter space of
this family with a statistical analysis. We find that microstate mass and spin
multipole moments are typically (but not always) larger that those of a Kerr
black hole with the same mass and angular momentum. Furthermore, we find
numerical evidence that some invariants associated with the (dimensionless)
moments of these microstates grow monotonically with the microstate size and
display a global minimum at the black-hole limit, obtained when all centers
collide. Our analysis is relevant in the context of measurements of the
multipole moments of dark compact objects with electromagnetic and
gravitational-wave probes, and for observational tests to distinguish fuzzballs
from classical black holes.Comment: 29 pages, 1 figur
Non-commutative dynamics and roton-like spectra in bosonic and fermionic condensates
The relation between symmetry breaking in non-commutative cut-off field
theories and transitions to inhomogeneous phases in condensed matter is
discussed. The non-commutative dynamics can be regarded as an effective
description of the mechanisms which lead to inhomogeneous phase transitions and
their relation to the roton-like excitation spectrum. The typical
infrared-ultraviolet mixing in non-commutative theories contains the peculiar
ingredients to describe the interplay between short and long distance particle
interactions which is responsible for the non-uniform background and the roton
spectrum both in bosonic and fermionic condensates.Comment: 4 Pages, no figure
LDL-cholesterol control in the primary prevention of cardiovascular diseases. An expert opinion for clinicians and health professionals
Aims: Although adequate clinical management of patients with hypercholesterolemia without a history of known cardiovascular disease is essential for prevention, these subjects are often disregarded. Furthermore, the scientific literature on primary cardiovascular prevention is not as rich as that on secondary prevention; finally, physicians often lack adequate tools for the effective management of subjects in primary prevention and have to face some unsolved relevant issues. This document aims to discuss and review the evidence available on this topic and provide practical guidance. Data synthesis: Available algorithms and risk charts represent the main tool for the assessment of cardiovascular risk in patients in primary prevention. The accuracy of such an estimate can be substantially improved considering the potential contribution of some additional risk factors (C-reactive protein, lipoprotein(a), family history of cardiovascular disease) and conditions (environmental pollution, sleep quality, socioeconomic status, educational level) whose impact on the cardiovascular risk has been better understood in recent years. The availability of non-invasive procedures to evaluate subclinical atherosclerosis may help to identify subjects needing an earlier intervention. Unveiling the presence of these conditions will improve cardiovascular risk estimation, granting a more appropriate intervention. Conclusions: The accurate assessment of cardiovascular risk in subjects in primary prevention with the use of algorithms and risk charts together with the evaluation of additional factors will allow physicians to approach each patient with personalized strategies, which should translate into an increased adherence to therapy and, as a consequence, a reduced cardiovascular risk
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