1,610 research outputs found
Inequivalent Quantizations of Gauge Theories
It is known that the quantization of a system defined on a topologically
non-trivial configuration space is ambiguous in that many inequivalent quantum
systems are possible. This is the case for multiply connected spaces as well as
for coset spaces. Recently, a new framework for these inequivalent
quantizations approach has been proposed by McMullan and Tsutsui, which is
based on a generalized Dirac approach. We employ this framework for the
quantization of the Yang-Mills theory in the simplest fashion. The resulting
inequivalent quantum sectors are labelled by quantized non-dynamical
topological charges.Comment: 24 pages, LaTeX, to be publ. in Int.J.Mod.Phys.
Capture, Learning, and Synthesis of 3D Speaking Styles
Audio-driven 3D facial animation has been widely explored, but achieving
realistic, human-like performance is still unsolved. This is due to the lack of
available 3D datasets, models, and standard evaluation metrics. To address
this, we introduce a unique 4D face dataset with about 29 minutes of 4D scans
captured at 60 fps and synchronized audio from 12 speakers. We then train a
neural network on our dataset that factors identity from facial motion. The
learned model, VOCA (Voice Operated Character Animation) takes any speech
signal as input - even speech in languages other than English - and
realistically animates a wide range of adult faces. Conditioning on subject
labels during training allows the model to learn a variety of realistic
speaking styles. VOCA also provides animator controls to alter speaking style,
identity-dependent facial shape, and pose (i.e. head, jaw, and eyeball
rotations) during animation. To our knowledge, VOCA is the only realistic 3D
facial animation model that is readily applicable to unseen subjects without
retargeting. This makes VOCA suitable for tasks like in-game video, virtual
reality avatars, or any scenario in which the speaker, speech, or language is
not known in advance. We make the dataset and model available for research
purposes at http://voca.is.tue.mpg.de.Comment: To appear in CVPR 201
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Sphingosine-1-phosphate receptor 2 restrains egress of γδ T cells from the skin.
Maintenance of a population of IL-17-committed γδ T cells in the dermis is important in promoting tissue immunity. However, the signals facilitating γδ T cell retention within the dermis remain poorly understood. Here, we find that sphingosine-1-phosphate receptor 2 (S1PR2) acts in a cell-intrinsic manner to oppose γδ T cell migration from the dermis to the skin draining lymph node (dLN). Migration of dermal γδ T cells to the dLN under steady-state conditions occurs in an S1PR1-dependent manner. S1PR1 and CD69 are reciprocally expressed on dermal γδ T cells, with loss of CD69 associated with increased S1PR1 expression and enhanced migration to the dLN. γδ T cells lacking both S1PR2 and CD69 are impaired in their maintenance within the dermis. These findings provide a mechanism for how IL-17+ γδ T cells establish residence within the dermis and identify a role for S1PR2 in restraining the egress of tissue-resident lymphocytes
Happy birthday, IDRC
IDRC personnel. Poem composed in celebration of IDRC's fifth aniversary
An Analysis of the Representations of the Mapping Class Group of a Multi-Geon Three-Manifold
It is well known that the inequivalent unitary irreducible representations
(UIR's) of the mapping class group of a 3-manifold give rise to ``theta
sectors'' in theories of quantum gravity with fixed spatial topology. In this
paper, we study several families of UIR's of and attempt to understand the
physical implications of the resulting quantum sectors. The mapping class group
of a three-manifold which is the connected sum of with a finite number
of identical irreducible primes is a semi-direct product group. Following
Mackey's theory of induced representations, we provide an analysis of the
structure of the general finite dimensional UIR of such a group. In the picture
of quantized primes as particles (topological geons), this general
group-theoretic analysis enables one to draw several interesting qualitative
conclusions about the geons' behavior in different quantum sectors, without
requiring an explicit knowledge of the UIR's corresponding to the individual
primes.Comment: 52 pages, harvmac, 2 postscript figures, epsf required. Added an
appendix proving the semi-direct product structure of the MCG, corrected an
error in the characterization of the slide subgroup, reworded extensively.
All our analysis and conclusions remain as befor
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
Talking about weight talk : primary care practitioner knowledge, attitudes and practice
Background: Primary care practitioners (PCPs) have a vital role in patient weight management. This study investigates knowledge, attitudes and practice of UK PCPs regarding patient weight management. Methods: A cross-sectional questionnaire assessed PCP perceived knowledge, self-reported practice, attitudes towards overweight/obesity and actual knowledge regarding overweight and obesity management. Practitioners from NE Scotland were invited to participate. Results: Participants comprised 107 PCPs. Most participants viewed management of overweight and obesity as core to their roles and 75% reported discussing weight with overweight/obese patients. Management techniques included discussion and advice provision. Behavioural change techniques (BCTs) were reported infrequently, despite perceptions that patients lacked motivation to lose weight. A quarter of participants reported a lack of training and a third reported inadequate skills to manage overweight/obese patients. Mean percent correct for knowledge questions was approximately 53%. Barriers to patient weight management included lack of specialists for referral and limited time. Conclusions: This study confirmed a primary care role in managing weight in overweight/obese patients. Our finding that most participants reported discussing weight with their overweight or obese patients is unsupported by previously published research, however, a more comprehensive sample of practitioners is required to scrutinize this disparity. Incongruence exists between practitioners’ perceptions of difficulties associated with patient weight loss and the tools they use to address them. Inclusion of training in BCT, the provision of weight care specialists, or referral on to commercial weight loss organizations may provide more effective pathways for PCPs to assist weight loss for overweight/obese patients in primary care.PostprintPeer reviewe
On a Modification of the Boundary State Formalism in Off-shell String Theory
We examine the application of boundary states in computing amplitudes in
off-shell open string theory. We find a straightforward generalization of
boundary state which produces the correct matrix elements with on-shell closed
string states.Comment: Latex, 10 pages, refs added, minor typos correcte
Path Integrals on Riemannian Manifolds with Symmetry and Induced Gauge Structure
We formulate path integrals on any Riemannian manifold which admits the
action of a compact Lie group by isometric transformations. We consider a path
integral on a Riemannian manifold M on which a Lie group G acts isometrically.
Then we show that the path integral on M is reduced to a family of path
integrals on a quotient space Q=M/G and that the reduced path integrals are
completely classified by irreducible unitary representations of G. It is not
necessary to assume that the action of G on M is either free or transitive.
Hence our formulation is applicable to a wide class of manifolds, which
includes inhomogeneous spaces, and it covers all the inequivalent
quantizations. To describe the path integral on inhomogeneous space,
stratification geometry, which is a generalization of the concept of principal
fiber bundle, is necessarily introduced. Using it we show that the path
integral is expressed as a product of three factors; the rotational energy
amplitude, the vibrational energy amplitude, and the holonomy factor. When a
singular point arises in , we determine the boundary condition of the path
integral kernel for a path which runs through the singularity.Comment: 20 pages, no figur
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