60 research outputs found
Looking through the QCD conformal window with perturbation theory
We study the conformal window of QCD using perturbation theory, starting from the perturbative upper edge and going down as much as we can towards the strongly coupled regime. We do so by exploiting the available five-loop
computation of the -function and employing Borel resummation techniques both for the ordinary perturbative series and for the Banks-Zaks conformal expansion. Large- results are also used. We argue that the perturbative series for the -function is most likely asymptotic and non-Borel resummable, yet Borel resummation techniques allow to improve on ordinary perturbation theory. We find
substantial evidence that QCD with flavours flows in the IR to a conformal field theory. Though the evidence is weaker, we find indications that also might sit within the conformal window. We also compute the value
of the mass anomalous dimension at the fixed point and compare it with the available lattice results. The conformal window might extend for lower values of , but our methods break down for n_f<11, where we expect that non-perturbative effects become important. A similar analysis is performed in the Veneziano limit
Trends in the incidence of adenocarcinoma of the oesophagus and cardia in the Netherlands 1989–2003
Over the 15-year period 1989–2003, the incidence of oesophagus–cardia adenocarcinoma in the Netherlands rose annually by 2.6% for males and 1.2% for females. This was the net outcome of annual increases in the incidence of adenocarcinoma of the oesophagus (ACO) of 7.2% for males and 3.5% for females and annual declines in the incidence of adenocarcinoma of the gastric cardia (AGC) of more than 1% for both genders. Nonlinear cohort patterns were found in females with ACO and for both genders in AGC; a nonlinear period pattern was observed only in males with AGC. These differing epidemiological patterns for ACO and AGC do not support a common aetiology. Proposed underlying factors for the rise in ACO incidence appear to have little effect on AGC incidence. This and the secular decline in smoking among males may have led to the decline in AGC incidence
Is the meiofauna a good indicator for climate change and anthropogenic impacts?
Our planet is changing, and one of the most pressing challenges facing the scientific community revolves around understanding how ecological communities respond to global changes. From coastal to deep-sea ecosystems, ecologists are exploring new areas of research to find model organisms that help predict the future of life on our planet. Among the different categories of organisms, meiofauna offer several advantages for the study of marine benthic ecosystems. This paper reviews the advances in the study of meiofauna with regard to climate change and anthropogenic impacts. Four taxonomic groups are valuable for predicting global changes: foraminifers (especially calcareous forms), nematodes, copepods and ostracods. Environmental variables are fundamental in the interpretation of meiofaunal patterns and multistressor experiments are more informative than single stressor ones, revealing complex ecological and biological interactions. Global change has a general negative effect on meiofauna, with important consequences on benthic food webs. However, some meiofaunal species can be favoured by the extreme conditions induced by global change, as they can exhibit remarkable physiological adaptations. This review highlights the need to incorporate studies on taxonomy, genetics and function of meiofaunal taxa into global change impact research
Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases
The production of peroxide and superoxide is an inevitable consequence of
aerobic metabolism, and while these particular "reactive oxygen species" (ROSs)
can exhibit a number of biological effects, they are not of themselves
excessively reactive and thus they are not especially damaging at physiological
concentrations. However, their reactions with poorly liganded iron species can
lead to the catalytic production of the very reactive and dangerous hydroxyl
radical, which is exceptionally damaging, and a major cause of chronic
inflammation. We review the considerable and wide-ranging evidence for the
involvement of this combination of (su)peroxide and poorly liganded iron in a
large number of physiological and indeed pathological processes and
inflammatory disorders, especially those involving the progressive degradation
of cellular and organismal performance. These diseases share a great many
similarities and thus might be considered to have a common cause (i.e.
iron-catalysed free radical and especially hydroxyl radical generation). The
studies reviewed include those focused on a series of cardiovascular, metabolic
and neurological diseases, where iron can be found at the sites of plaques and
lesions, as well as studies showing the significance of iron to aging and
longevity. The effective chelation of iron by natural or synthetic ligands is
thus of major physiological (and potentially therapeutic) importance. As
systems properties, we need to recognise that physiological observables have
multiple molecular causes, and studying them in isolation leads to inconsistent
patterns of apparent causality when it is the simultaneous combination of
multiple factors that is responsible. This explains, for instance, the
decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference
Design or development? Beyond the LP-STS debate; inputs from a Volvo truck case
In this paper, we will show that the debate between advocates of Lean production and the socio-technical approach has concentrated too much on the design aspect of the production structure, while neglecting the development aspect of teamwork. This paper addresses the question whether it is production design or team development that explains business performance and the quality of working life. The data are taken from four departments of the Volvo truck plant in Umea (Sweden) that is redesigning from socio-technical based assembly to line-assembly. We conclude that good design of the production structure is necessary, but not sufficient for good performance; team development is just as important, although it requires a favorable context
Feasibility Study of Attitude Determination for All-Rotating Unmanned Aerial Vehicles in Steady Flight
Perceived opportunities and challenges of artificial intelligence within the police - a public management perspective
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