904 research outputs found
Effect of tamoxifen on Ki67 labelling index in human breast tumours and its relationship to oestrogen and progesterone receptor status.
This study aimed to investigate the effect of tamoxifen on breast tumour levels of oestrogen and progesterone receptor (ER and PR) and proliferation as defined by the Ki67 antibody. A group of primary breast cancer patients was randomised to receive either tamoxifen (n = 59) or placebo (n = 44) treatment in the interval between clinic and surgery (median 21 days). Frozen sections of breast tumour biopsies obtained before and after treatment were stained immunocytochemically to obtain the percentage of nuclei containing ER and PR, and a Ki67 labelling index (LI). Tamoxifen-treated patients had a median Ki67 LI of 5.6% in the first biopsy falling to 3.0% in the second biopsy (P < 0.001 by Wilcoxon's matched pairs test), whereas placebo-treated patients had a median Ki67 LI of 5.4% in the first biopsy and 5.75% in the second (no significant difference). No significant differences were observed when the median %ER or %PR staining before and after treatment were compared. The Ki67 LI tended to increase with increasing histological grade and was greater in tumours that were ER - ve compared to those that were ER + ve (> 5% nuclei stained), median 7.8% and 4.3% respectively (P = 0.011 by Mann-Whitney U-test). However, the decline in tumour Ki67 LI following anti-oestrogen treatment failed to correlate with ER and PR status or to predict recurrence over a short follow-up period. To our knowledge, this is the first time that tamoxifen treatment has been shown to reduce the Ki67 LI in human breast tumours in vivo. These data indicate that staining with the Ki67 antibody may be useful in monitoring response to anti-oestrogen therapy
The Boundary State Formalism and Conformal Invariance in Off-shell String Theory
We present a generalization of the boundary state formalism for the bosonic
string that allows us to calculate the overlap of the boundary state with
arbitrary closed string states. We show that this generalization exactly
reproduces world-sheet sigma model calculations, thus giving the correct
overlap with both on- and off-shell string states, and that this new boundary
state automatically satisfies the requirement for integrated vertex operators
in the case of non-conformally invariant boundary interactions.Comment: 19 pages, 0 figure
Behaviour of three charged particles on a plane under perpendicular magnetic field
We consider the problem of three identical charged particles on a plane under
a perpendicular magnetic field and interacting through Coulomb repulsion. This
problem is treated within Taut's framework, in the limit of vanishing center of
mass vector , which corresponds to the strong magnetic
field limit, occuring for example in the Fractional Quantum Hall Effect. Using
the solutions of the biconfluent Heun equation, we compute the eigenstates and
show that there is two sets of solutions. The first one corresponds to a system
of three independent anyons which have their angular momenta fixed by the value
of the magnetic field and specified by a dimensionless parameter , the ratio of , the magnetic length, over , the Bohr
radius. This anyonic character, consistent with quantum mechanics of identical
particles in two dimensions, is induced by competing physical forces. The
second one corresponds to the case of the Landau problem when .
Finally we compare these states with the quantum Hall states and find that the
Laughlin wave functions are special cases of our solutions under certains
conditions.Comment: 15 pages, 3 figures, Accepeted in JP
Landscape effects on nest site selection and nest success of Northern Lapwing Vanellus vanellus in lowland wet grasslands
Capsule: Northern Lapwing Vanellus vanellus avoid nesting close to small woodland patches but nest predation rates do not vary with distance to woodland patches, either because risky areas are avoided or perceived nest predation risk does not reflect actual risk. Aims: To explore the effects of woodland patches in wet grassland landscapes on nest distribution and success of Lapwings. Methods: We quantified the effect of woodland patches on the distribution and outcome of Lapwing nests across four wet grassland sites by mapping nest distribution and monitoring nest outcomes. Results: Lapwing nested significantly further from woods than expected by chance. Neither nest predation rates nor the probability of predation occurring at night (thus primarily mammalian predators) or day (primarily avian predators) varied in relation to distance from woodland patches. Conclusions: High levels of nest and chick predation in wet grassland landscapes limit the capacity for breeding wader populations to be self-sustaining. Consequently, identifying manageable landscape features that influence predation rates is an important focus of conservation research. Lapwing avoid breeding close to woodland but, as nest predation rates do not vary with distance from woodland patches, their removal may increase the area of suitable nesting habitat but is unlikely to substantially influence productivity
Fresh Cement as a Frictional Non-Brownian Suspension
Cement is an essential construction material due to its ability to flow before later setting, however the rheological properties must be tightly controlled. Despite this, much understanding remains empirical. Using a combination of continuous and oscillatory shear flow, we compare fresh Portland cement suspensions to previous measurements on model non-Brownian suspensions to gain a micro-physical understanding. Comparing steady and small-amplitude oscillatory shear, we reveal two distinct jamming concentrations, and rcp, where the respective yield stresses diverge. As in model suspensions, the steady-shear jamming point is notably below the oscillatory jamming point, < rcp, suggesting that it is tied to frictional particle contacts. These results indicate that recently established models for the rheology of frictional, adhesive non-Brownian suspensions can be applied to fresh cement pastes, offering a new framework to understand the role of additives and fillers. Such micro-physical understanding can guide formulation changes to improve performance and reduce environmental impact
Unitary Equivalence of the Metric and Holonomy Formulations of 2+1 Dimensional Quantum Gravity on the Torus
Recent work on canonical transformations in quantum mechanics is applied to
transform between the Moncrief metric formulation and the Witten-Carlip
holonomy formulation of 2+1-dimensional quantum gravity on the torus. A
non-polynomial factor ordering of the classical canonical transformation
between the metric and holonomy variables is constructed which preserves their
classical modular transformation properties. An extension of the definition of
a unitary transformation is briefly discussed and is used to find the inner
product in the holonomy variables which makes the canonical transformation
unitary. This defines the Hilbert space in the Witten-Carlip formulation which
is unitarily equivalent to the natural Hilbert space in the Moncrief
formulation. In addition, gravitational theta-states arising from ``large''
diffeomorphisms are found in the theory.Comment: 31 pages LaTeX [Important Revision: a section is added constructing
the inner product/Hilbert space for the Witten-Carlip holonomy formulation;
the proof of unitary equivalence of the metric and holonomy formulations is
then completed. Other additions include discussion of relation of canonical
and unitary transformations. Title/abstract change.
The power of animation:encouraging doctors to access support for psychological wellbeing
The COVID-19 pandemic has exacerbated already high rates of poor psychological wellbeing in doctors. Many doctors perceive a stigma associated with acknowledging psychological wellbeing concerns, resulting in a reluctance to seek support for those concerns. The aim of this study was to develop a theoretically-informed and evidence-based composite narrative animation (CNA) to encourage doctors to access support for psychological wellbeing, and to evaluate the acceptability of the CNA.A composite narrative was developed from an evidence-base of interviews with 27 GP participants across Scotland (May–July 2020). The Behaviour Change Wheel was used to identify behaviour change techniques (BCTs) to be embedded within the CNA. The narrative was turned into a script in collaboration with an animation company. A brief animation ‘Jane the GP’ was developed reflecting specific BCTs.Scottish doctors (n = 83) were asked for their views on acceptability of the CNA concept, and subsequently asked to provide views on the acceptability of the CNA after viewing it. Participants thought the concept of a CNA was novel but may not appeal to all. After viewing the CNA, the widespread view was that it portrayed an authentic experience, could reduce stigma around seeking support for psychological wellbeing, and highlighted formal routes to access such support.CNAs are a novel and acceptable intervention method for encouraging doctors to access support for psychological wellbeing. The use of a theory driven intervention development framework to create the CNA facilitates the link between theory and practice
The power of animation:encouraging doctors to access support for psychological wellbeing
The COVID-19 pandemic has exacerbated already high rates of poor psychological wellbeing in doctors. Many doctors perceive a stigma associated with acknowledging psychological wellbeing concerns, resulting in a reluctance to seek support for those concerns. The aim of this study was to develop a theoretically-informed and evidence-based composite narrative animation (CNA) to encourage doctors to access support for psychological wellbeing, and to evaluate the acceptability of the CNA.A composite narrative was developed from an evidence-base of interviews with 27 GP participants across Scotland (May–July 2020). The Behaviour Change Wheel was used to identify behaviour change techniques (BCTs) to be embedded within the CNA. The narrative was turned into a script in collaboration with an animation company. A brief animation ‘Jane the GP’ was developed reflecting specific BCTs.Scottish doctors (n = 83) were asked for their views on acceptability of the CNA concept, and subsequently asked to provide views on the acceptability of the CNA after viewing it. Participants thought the concept of a CNA was novel but may not appeal to all. After viewing the CNA, the widespread view was that it portrayed an authentic experience, could reduce stigma around seeking support for psychological wellbeing, and highlighted formal routes to access such support.CNAs are a novel and acceptable intervention method for encouraging doctors to access support for psychological wellbeing. The use of a theory driven intervention development framework to create the CNA facilitates the link between theory and practice
Are All Particles Identical?
We consider the possibility that all particles in the world are fundamentally
identical, i.e., belong to the same species. Different masses, charges, spins,
flavors, or colors then merely correspond to different quantum states of the
same particle, just as spin-up and spin-down do. The implications of this
viewpoint can be best appreciated within Bohmian mechanics, a precise
formulation of quantum mechanics with particle trajectories. The implementation
of this viewpoint in such a theory leads to trajectories different from those
of the usual formulation, and thus to a version of Bohmian mechanics that is
inequivalent to, though arguably empirically indistinguishable from, the usual
one. The mathematical core of this viewpoint is however rather independent of
the detailed dynamical scheme Bohmian mechanics provides, and it amounts to the
assertion that the configuration space for N particles, even N
``distinguishable particles,'' is the set of all N-point subsets of physical
3-space.Comment: 12 pages LaTeX, no figure
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