198 research outputs found
Barbara\u27s Fart Creates a Fracas
We read address, swerved, veered car at West Exeter Street; we were at Barbara\u27s fete, as were Vera, Bert, Bart, Dave, Fred, Sara, Steve. Actress Barbara, a faded stage star, fretted re: fat, crafted decreased-stew, beer bread, watercress, grated feta, brew, sweet dessert served were fat-free
Topological Dilatonic Supergravity Theories
We present a central extension of the super-Poincar\'e algebra in two
dimensions. Besides the usual Poincar\'e generators and the
supersymmetry generators we have Grassmann generators, a bosonic
internal symmetry generator and a central charge. We then build up the
topological gauge theory associated to this algebra. We can solve the classical
field equations for the fields which do not belong to the supergravity
multiplet and to a Lagrange multiplier multiplet. The resulting topological
supergravity theory turns out to be non-local in the fermionic sector.Comment: 11 pages, plain TeX, IFUSP-P/112
On the symplectic structures arising in Optics
Geometric optics is analysed using the techniques of Presymplectic Geometry.
We obtain the symplectic structure of the space of light rays in a medium of a
non constant refractive index by reduction from a presymplectic structure, and
using adapted coordinates, we find Darboux coordinates. The theory is
illustrated with some examples and we point out some simple physical
applicationsComment: AmsTeX file and 2 figures (epsf required). To appear in Forsch. der
Physik. This version replaces that of (96/02/09) where postcript files
containing figures were corrupte
Group-quantization of non-linear sigma models: particle on S^2 revisited
We present the quantum mechanics of "partial-trace" non-linear sigma models,
on the grounds of a fully symmetry-based procedure. After the general scheme is
sketched, the particular example of a particle on the two-sphere is explicitly
developed. As a remarkable feature, no explicit constraint treatment is
required nor ordering ambiguities do appear. Moreover, the energy spectrum is
recovered without extra terms in the curvature of the sphere.Comment: 8 page
The spin-statistics connection in classical field theory
The spin-statistics connection is obtained for a simple formulation of a
classical field theory containing even and odd Grassmann variables. To that
end, the construction of irreducible canonical realizations of the rotation
group corresponding to general causal fields is reviewed. The connection is
obtained by imposing local commutativity on the fields and exploiting the
parity operation to exchange spatial coordinates in the scalar product of
classical field evaluated at one spatial location with the same field evaluated
at a distinct location. The spin-statistics connection for irreducible
canonical realizations of the Poincar\'{e} group of spin is obtained in the
form: Classical fields and their conjugate momenta satisfy fundamental
field-theoretic Poisson bracket relations for 2 even, and fundamental
Poisson antibracket relations for 2 oddComment: 27 pages. Typos and sign error corrected; minor revisions to tex
The local structure of n-Poisson and n-Jacobi manifolds
N-Lie algebra structures on smooth function algebras given by means of
multi-differential operators, are studied. Necessary and sufficient conditions
for the sum and the wedge product of two -Poisson sructures to be again a
multi-Poisson are found. It is proven that the canonical -vector on the dual
of an n-Lie algebra g is n-Poisson iff dim(g) are not greater than n+1. The
problem of compatibility of two n-Lie algebra structures is analyzed and the
compatibility relations connecting hereditary structures of a given n-Lie
algebra are obtained. (n+1)-dimensional n-Lie algebras are classified and their
"elementary particle-like" structure is discovered. Some simple applications to
dynamics are discussed.Comment: 45 pages, latex, no figure
Bianchi Cosmologies with Anisotropic Matter: Locally Rotationally Symmetric Models
The dynamics of cosmological models with isotropic matter sources (perfect
fluids) is extensively studied in the literature; in comparison, the dynamics
of cosmological models with anisotropic matter sources is not. In this paper we
consider spatially homogeneous locally rotationally symmetric solutions of the
Einstein equations with a large class of anisotropic matter models including
collisionless matter (Vlasov), elastic matter, and magnetic fields. The
dynamics of models of Bianchi types I, II, and IX are completely described; the
two most striking results are the following: (i) There exist matter models,
compatible with the standard energy conditions, such that solutions of Bianchi
type IX (closed cosmologies) need not necessarily recollapse; there is an open
set of forever expanding solutions. (ii) Generic type IX solutions associated
with a matter model like Vlasov matter exhibit oscillatory behavior toward the
initial singularity. This behavior differs significantly from that of
vacuum/perfect fluid cosmologies; hence "matter matters". Finally, we indicate
that our methods can probably be extended to treat a number of open problems,
in particular, the dynamics of Bianchi type VIII and Kantowski-Sachs solutions.Comment: 64 pages, 19 Figure
Single Boson Images Via an Extended Holstein Primakoff Mapping
The Holstein-Primakoff mapping for pairs of bosons is extended in order to
accommodate single boson mapping. The proposed extension allows a variety of
applications and especially puts the formalism at finite temperature on firm
grounds. The new mapping is applied to the O(N+1) anharmonic oscillator with
global symmetry broken down to O(N). It is explicitly demonstrated that
N-Goldstone modes appear. This result generalizes the Holstein-Primakoff
mapping for interacting boson as developed in ref.[1].Comment: 9 pages, LaTeX. Physical content unchanged. Unnecessary figure
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Disease management patterns for postmenopausal women in Europe with hormone-receptor-positive, human epidermal growth factor receptor-2 negative advanced breast cancer.
peer reviewedAbstract Background: International guidelines for hormone-receptor-positive (HR+), human epidermal growth factor receptor-2 negative (HER2-) advanced breast cancer (BC) recommend sequential lines of hormonal therapy (HT), and only recommend chemotherapy for patients with extensive visceral involvement or rapidly progressive disease. This study evaluated actual physician-reported treatments for advanced BC in Europe. Methods: We conducted a retrospective chart review of 355 postmenopausal women with HR+, HER2- advanced BC who progressed on >/=1 line of HT (adjuvant or advanced) and completed >/=1 line of chemotherapy (advanced). Treatment choice was evaluated for each line of therapy. Results: Of 355 patients, 111 (31%) received first-line chemotherapy, whereas 218 (61%) and 26 (7%) switched from HT to chemotherapy in second and third line, respectively. More patients receiving first-line HT had bone metastases (73% vs 27% chemotherapy). Patients treated with first-line chemotherapy had more brain (12% vs 3% HT) or extensive liver (13% vs 6% HT) metastases. Subgroup analysis of 188 patients who received first-line HT and had de novo advanced BC or relapsed/recurrent disease more than 1 year after adjuvant therapy found that the majority (89%; n = 167) of these patients switched to chemotherapy in second line. However, among these 167 patients, 27% had no significant changes in metastases between first and second line. Among the 73% of patients who had significant changes in metastases, 20% had no brain metastases or extensive visceral disease. Conclusions: Our study suggests that the guideline-recommended use of multiple HT lines is open to interpretation and that optimal treatment for European postmenopausal women with HR+, HER2- advanced BC who responded to HT may not be achieved
Projective representation of k-Galilei group
The projective representations of k-Galilei group G_k are found by
contracting the relevant representations of k-Poincare group. The projective
multiplier is found. It is shown that it is not possible to replace the
projective representations of G_k by vector representations of some its
extension.Comment: 15 pages Latex fil
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