6,787 research outputs found
Euler Chern Simons Gravity from Lovelock Born Infeld Gravity
In the context of a gauge theoretical formulation, higher dimensional gravity
invariant under the AdS group is dimensionally reduced to Euler-Chern-Simons
gravity. The dimensional reduction procedure of Grignani-Nardelli [Phys. Lett.
B 300, 38 (1993)] is generalized so as to permit reducing D-dimensional Lanczos
Lovelock gravity to d=D-1 dimensions.Comment: 6 pages, no figures, accepted for publication in Phys. Lett.
Standard General Relativity from Chern-Simons Gravity
Chern-Simons models for gravity are interesting because they provide with a
truly gauge-invariant action principle in the fiber-bundle sense. So far, their
main drawback has largely been the perceived remoteness from standard General
Relativity, based on the presence of higher powers of the curvature in the
Lagrangian (except, remarkably, for three-dimensional spacetime). Here we
report on a simple model that suggests a mechanism by which standard General
Relativity in five-dimensional spacetime may indeed emerge at a special
critical point in the space of couplings, where additional degrees of freedom
and corresponding "anomalous" Gauss-Bonnet constraints drop out from the
Chern-Simons action. To achieve this result, both the Lie algebra g and the
symmetric g-invariant tensor that define the Chern-Simons Lagrangian are
constructed by means of the Lie algebra S-expansion method with a suitable
finite abelian semigroup S. The results are generalized to arbitrary odd
dimensions, and the possible extension to the case of eleven-dimensional
supergravity is briefly discussed.Comment: 6 pages, no figures; v2: published versio
Effectiveness of delayed-release dimethyl fumarate on patient-reported outcomes and clinical measures in patients with relapsing-remitting multiple sclerosis in a real-world clinical setting: PROTEC.
Ensaio clĂnico PROTEC, Protocolo nÂș 109MS408Abstract
BACKGROUND:
Patient-reported outcomes (PRO) and clinical outcomes give a broad assessment of relapsing-remitting multiple sclerosis (RRMS) disease.
OBJECTIVE:
The aim is to evaluate the effectiveness of delayed-release dimethyl fumarate (DMF) on disease activity and PROs in patients with RRMS in the clinic.
METHODS:
PROTEC, a phase 4, open-label, 12-month observational study, assessed annualized relapse rate (ARR), proportion of patients relapsed, and changes in PROs. Newly diagnosed and early MS (â€3.5 EDSS and â€1 relapse in the prior year) patient subgroups were evaluated.
RESULTS:
Unadjusted ARR at 12 months post-DMF versus 12 months before DMF initiation was 75% lower (0.161 vs. 0.643, pâ<â0.0001) overall (nâ=â1105) and 84%, 77%, and 71% lower in newly diagnosed, â€3.5 EDSS, and â€1 relapse subgroups, respectively. Overall, 88% of patients were relapse-free 12 months after DMF initiation (84%, newly diagnosed; 88%, â€3.5 EDSS; 88%, â€1 relapse). PRO measures for fatigue, treatment satisfaction, daily living, and work improved significantly over 12 months of DMF versus baseline.
CONCLUSION:
At 12 months after versus 12 months before DMF initiation, ARR was significantly lower, the majority of patients were relapse-free, and multiple PRO measures showed improvement (overall and for subgroups), suggesting that DMF is effective based on clinical outcomes and from a patient perspective.Clinical trial: A Study Evaluating the Effectiveness of Tecfidera (Dimethyl Fumarate) on Multiple Sclerosis (MS) Disease Activity and Patient-Reported Outcomes (PROTEC), NCT01930708,info:eu-repo/semantics/publishedVersio
Multifactor Productivity and its Determinants: Al Empirical Analysis for Mexican Manufacturing.
We use data from the Annual Industrial Survey for 1996-2003. First, we estimate production functions by means of growth accounting exercises and panel data econometrics for the whole sector and for 14 comprehensive groups. Various measures of Multifactor Productivity (MFP) are constructed, as we consider diverse combinations of inputs with capital, labour, electricity and transport. This allows us to compare MFP growth rates between groups. Second, we analyse econometrically some of the determinants of MFP and Labour Productivity (LP) growth. We find that, on the one hand, there is some evidence of a positive relationship between market concentration and technology adoption; on the other hand, both technology adoption and human capital seem to be promoting productivity, whilst market concentration is exerting a negative influence on it. In sum, our results suggest that, once controlling for the effect on technology adoption, more concentration (conversely, less competition) has a negative impact on productivity.Panel data, Productivity, Manufacturing, Competition
Translog Cost Functions: An Application for Mexican Manufacturing.
We use translog cost functions to estimate own-price and substitution elasticities of input demands, economies of scale and average costs in Mexican manufacturing. Data from the Mexican Annual Industrial Survey is used for 1996, 2000 and 2003. We show that a model that allows for nonhomotheticity and nonunitary elasticities of substitution is appropriate to represent the production structure. Allen-Uzawa elasticities indicate the existence of substitution possibilities amongst inputs. The demand for electricity is essentially unitary elastic. All cross-price elasticities are less than one. Both scale economies and average costs diminish as the size of activity class increases. Economies of scale increased for any level of output. The differences in average costs between small and large activity classes were reduced and some disparities prevail in a number of manufacturing groups.Simultaneous equation models, Translog cost function, Manufacturing
Dual Formulation of the Lie Algebra S-expansion Procedure
The expansion of a Lie algebra entails finding a new, bigger algebra G,
through a series of well-defined steps, from an original Lie algebra g. One
incarnation of the method, the so-called S-expansion, involves the use of a
finite abelian semigroup S to accomplish this task. In this paper we put
forward a dual formulation of the S-expansion method which is based on the dual
picture of a Lie algebra given by the Maurer-Cartan forms. The dual version of
the method is useful in finding a generalization to the case of a gauge free
differential algebra, which in turn is relevant for physical applications in,
e.g., Supergravity. It also sheds new light on the puzzling relation between
two Chern-Simons Lagrangians for gravity in 2+1 dimensions, namely the
Einstein-Hilbert Lagrangian and the one for the so-called "exotic gravity".Comment: 12 pages, no figure
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