596 research outputs found
Positioning uncertainties for pediatric craniospinal irradiation and the impact of image guidance
The Mikheyev-Smirnov-Wolfenstein Effect as a Probe of the Solar Interior
We relate the MSW effect to the efective absorption of the electronic
collective motion energy by retaining the imaginary part of the index of
refraction associated with the charged-current scattering and show that the
small angle MSW solution to the solar neutrino anomaly can be used as a probe
of the physical conditions of the solar interior if it is correct. We find that
the constraint on the absorption imposed by the small angle MSW solution and
the theoretical estimate of the absorption by the Boltzmann kinetic theory are
consistent, which shows that a consistent theoretical picture can be developed
when plasma absorption processes are taken into account.Comment: 4 pages, no figure, REVTeX, to appear in Phys. Rev.
Severe COVID-19 in an APS1 patient with interferon autoantibodies treated with plasmapheresis
Very high frequency gravitational wave background in the universe
Astrophysical sources of high frequency gravitational radiation are
considered in association with a new interest to very sensitive HFGW receivers
required for the laboratory GW Hertz experiment. A special attention is paid to
the phenomenon of primordial black holes evaporation. They act like black body
to all kinds of radiation, including gravitons, and, therefore, emit an
equilibrium spectrum of gravitons during its evaporation. Limit on the density
of high frequency gravitons in the Universe is obtained, and possibilities of
their detection are briefly discussed.Comment: 14 page
Human NK Cells Differ More in Their KIR2DL1-Dependent Thresholds for HLA-Cw6-Mediated Inhibition than in Their Maximal Killing Capacity
In this study we have addressed the question of how activation and inhibition of human NK cells is regulated by the expression level of MHC class I protein on target cells. Using target cell transfectants sorted to stably express different levels of the MHC class I protein HLA-Cw6, we show that induction of degranulation and that of IFN-γ secretion are not correlated. In contrast, the inhibition of these two processes by MHC class-I occurs at the same level of class I MHC protein. Primary human NK cell clones were found to differ in the amount of target MHC class I protein required for their inhibition, rather than in their maximum killing capacity. Importantly, we show that KIR2DL1 expression determines the thresholds (in terms of MHC I protein levels) required for NK cell inhibition, while the expression of other receptors such as LIR1 is less important. Furthermore, using mathematical models to explore the dynamics of target cell killing, we found that the observed delay in target cell killing is exhibited by a model in which NK cells require some activation or priming, such that each cell can lyse a target cell only after being activated by a first encounter with the same or a different target cell, but not by models which lack this feature
The nature of the short wavelength excitations in vitreous silica: X-Rays Brillouin scattering study
The dynamical structure factor (S(Q,E)) of vitreous silica has been measured
by Inelastic X-ray Scattering varying the exchanged wavevector (Q) at fixed
exchanged energy (E) - an experimental procedure that, contrary to the usual
one at constant Q, provides spectra with much better identified inelastic
features. This allows the first direct evidence of Brillouin peaks in the
S(Q,E) of SiO_2 at energies above the Boson Peak (BP) energy, a finding that
excludes the possibility that the BP marks the transition from propagating to
localised dynamics in glasses.Comment: 4 pages, 3 Postscript figures. To appear in Physical Review Letter
The read-across hypothesis and environmental risk assessment of pharmaceuticals
This article is made available through the Brunel Open Access Publishing Fund. Copyright © 2013 American Chemical Society.Pharmaceuticals in the environment have received increased attention over the past decade, as they are ubiquitous in rivers and waterways. Concentrations are in sub-ng to low μg/L, well below acute toxic levels, but there are uncertainties regarding the effects of chronic exposures and there is a need to prioritise which pharmaceuticals may be of concern. The read-across hypothesis stipulates that a drug will have an effect in non-target organisms only if the molecular targets such as receptors and enzymes have been conserved, resulting in a (specific) pharmacological effect only if plasma concentrations are similar to human therapeutic concentrations. If this holds true for different classes of pharmaceuticals, it should be possible to predict the potential environmental impact from information obtained during the drug development process. This paper critically reviews the evidence for read-across, and finds that few studies include plasma concentrations and mode of action based effects. Thus, despite a large number of apparently relevant papers and a general acceptance of the hypothesis, there is an absence of documented evidence. There is a need for large-scale studies to generate robust data for testing the read-across hypothesis and developing predictive models, the only feasible approach to protecting the environment.BBSRC Industrial Partnership Award BB/
I00646X/1 and BBSRC Industrial CASE Partnership Studentship
BB/I53257X/1 with AstraZeneca Safety Health and
Environment Research Programme
Long-time discrete particle effects versus kinetic theory in the self-consistent single-wave model
The influence of the finite number N of particles coupled to a monochromatic
wave in a collisionless plasma is investigated. For growth as well as damping
of the wave, discrete particle numerical simulations show an N-dependent long
time behavior resulting from the dynamics of individual particles. This
behavior differs from the one due to the numerical errors incurred by Vlasov
approaches. Trapping oscillations are crucial to long time dynamics, as the
wave oscillations are controlled by the particle distribution inhomogeneities
and the pulsating separatrix crossings drive the relaxation towards thermal
equilibrium.Comment: 11 pages incl. 13 figs. Phys. Rev. E, in pres
Systematic Genetic Nomenclature for Type VII Secretion Systems
CITATION: Bitter, W., et al. 2009. Systematic genetic nomenclature for type VII secretion systems. PLoS Pathogens, 5(10): 1-6, doi: 10.1371/journal.ppat.1000507.The original publication is available at http://journals.plos.org/plospathogensMycobacteria, such as the etiological
agent of human tuberculosis, Mycobacterium
tuberculosis, are protected by an impermeable
cell envelope composed of an inner
cytoplasmic membrane, a peptidoglycan
layer, an arabinogalactan layer, and an
outer membrane. This second membrane
consists of covalently linked, tightly packed
long-chain mycolic acids [1,2] and noncovalently
bound shorter lipids involved in
pathogenicity [3–5]. To ensure protein
transport across this complex cell envelope,
mycobacteria use various secretion pathways,
such as the SecA1-mediated general
secretory pathway [6,7], an alternative
SecA2-operated pathway [8], a twin-arginine
translocation system [9,10], and a
specialized secretion pathway variously
named ESAT-6-, SNM-, ESX-, or type
VII secretion [11–16]. The latter pathway,
hereafter referred to as type VII secretion
(T7S), has recently become a large and
competitive research topic that is closely
linked to studies of host–pathogen interactions
of M. tuberculosis [17] and other
pathogenic mycobacteria [16]. Molecular
details are just beginning to be revealed
[18–22] showing that T7S systems are
complex machineries with multiple components
and multiple substrates. Despite
their biological importance, there has been
a lack of a clear naming policy for the
components and substrates of these systems.
As there are multiple paralogous T7S
systems within the Mycobacteria and
orthologous systems in related bacteria,
we are concerned that, without a unified
nomenclature system, a multitude of redundant
and obscure gene names will be
used that will inevitably lead to confusion
and hinder future progress. In this opinion
piece we will therefore propose and introduce
a systematic nomenclature with
guidelines for name selection of new
components that will greatly facilitate
communication and understanding in this
rapidly developing field of research.http://journals.plos.org/plospathogens/article?id=10.1371%2Fjournal.ppat.1000507Publisher's versio
How do we perceive activity pacing in rheumatology care? An international delphi survey
Background Activity pacing is a recommended non-pharmacological intervention for the management of rheumatic and musculoskeletal diseases in international clinical guidelines. In clinical practice, activity pacing aims at adapting daily activities, and is often an important component of self-management programs. However, despite its wide endorsement in clinical practice, to date activity pacing is still a poorly understood concept.
Objectives To achieve consensus by means of an international Delphi exercise on the most important aspects of activity pacing as an intervention within non-pharmacological rheumatology care.
Methods An international, multidisciplinary expert panel comprising 60 clinicians and/or healthcare providers experienced with activity pacing across 12 different countries participated in a Delphi survey. Over four Delphi rounds, the panelists identified and ranked the most important goals of activity pacing, behaviours of activity pacing (the actions people take to meet the goal of activity pacing), strategies to change behaviour in activity pacing (for example goal setting) and contextual factors that should be acknowledged when instructing activity pacing. Besides, topics for future research on activity pacing were formulated and prioritized.
Results Of the 60 panelists, nearly two third (63%) completed all four Delphi rounds. The panel prioritized 9 goals, 11 behaviours, 9 strategies to change behaviour and 10 contextual factors of activity pacing. These items were integrated into a consensual list containing the most important aspects of activity pacing interventions in non-pharmacological rheumatology care. Furthermore, the Delphi panel prioritized 9 topics for future research on activity pacing which were included in a research agenda. This agenda highlights that future research should focus on the effectiveness of activity pacing interventions and on appropriate outcome measures to assess its effectiveness, as selected by 64% and 82% of the panelists, respectively.
Conclusions The diversity and number of items included in the consensual list developed in the current study reflect the heterogeneity of the concept of activity pacing. This study is an important first step to achieve better transparency and homogeneity within the concept of activity pacing for clinical practice and research
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