11,869 research outputs found
Gauge Fields and Singletons of
We show that -forms on describe both singletons and massless
particles. On the -dimensional boundary the singleton -form Lagrangian
reduces to the conformally invariant functional . All the
representations, singletons as well as massless, are zero center modules and
involve a vacuum mode. Two- and three-form singleton fields are required by
supersymmetry in AdS and AdS supergravity respectively.Comment: tex file, 13 page
Forecasting Euro-area recessions using time-varying binary response models for financial.
Recent macroeconomic evolutions during the years 2008 and 2009 have pointed out the impact of financial markets on economic activity. In this paper, we propose to evaluate the ability of a set of financial variables to forecast recessions in the euro area by using a non-linear binary response model associated with information combination. Especially, we focus on a time-varying probit model whose parameters evolve according to a Markov chain. For various forecast horizons, we provide a readable and leading signal of recession by combining information according to two combining schemes over the sample 1970-2006. First we average recession probabilities and second we linearly combine variables through a dynamic factor model in order to estimate an innovative factor-augmented probit model. Out-of-sample results over the period 2007-2008 show that financial variables would have been helpful in predicting a recession signal as September 2007, that is around six months before the effective start of the 2008-2009 recession in the euro area.Macroeconomic forecasting, Business cycles, Turning points, Financial markets, Non-linear time series, Combining forecasts.
Mass formulae and natural hierarchy in string effective supergravities
We study some conditions for the hierarchy to occur
naturally in a generic effective supergravity theory. Absence of fine-tuning
and perturbative calculability require that the effective potential has a
sliding gravitino mass and vanishing cosmological constant, up to corrections. In particular, cancellation of quadratically
divergent contributions to the one-loop effective potential should take place,
including the `hidden sector' of the theory. We show that these conditions can
be met in the effective supergravities derived from four-dimensional
superstrings, with supersymmetry broken either at the string tree level via
compactification, or by non-perturbative effects such as gaugino condensation.
A crucial role is played by some approximate scaling symmetries, which are
remnants of discrete target-space dualities in the large moduli limit. We
derive explicit formulae for the soft breaking terms arising from this class of
`large hierarchy compatible' (LHC) supergravities.Comment: 40 pages, no figures, CERN-TH.7192/94, LPTENS -94/12, UCLA/94/TEP13
(plain LATEX, to be run twice). Some trivial misprints and references have
been correcte
Simulating intergalactic quasar scintillation
Intergalactic scintillation of distant quasars is sensitive to free electrons
and therefore complements Ly absorption line experiments probing the
neutral intergalactic medium (IGM). We present a new scheme to compute IGM
refractive scintillation effects on distant sources in combination with
Adaptive Mesh Refinement cosmological simulations. First we validate our model
by reproducing the well-known interstellar scintillation (ISS) of Galactic
sources. The simulated cosmic density field is then used to infer the
statistical properties of intergalactic scintillation. Contrary to previous
claims, we find that the scattering measure of the simulated IGM at is
\langle \mbox{SM}_{\equ}\rangle=3.879, i.e. almost 40 times larger than for
the usually assumed smooth IGM. This yield an average modulation index ranging
from 0.01 ( GHz) up to 0.2 ( GHz); above \nu_{s}\gsim30
GHz the IGM contribution dominates over ISS modulation. We compare our model
with data from a quasar sample observed at \nu_{\obs}=8.4
GHz. For this high frequency (), high galactic
latitude sample ISS is negligible, and IGM scintillation can reproduce the
observed modulation with a 4% accuracy, without invoking intrinsic source
variability. We conclude by discussing the possibility of using IGM
scintillation as a tool to pinpoint the presence of intervening high-
groups/clusters along the line of sight, thus making it a probe suitably
complementing Sunyaev-Zeldovich data recently obtained by \textit{Planck}.Comment: 14 pages, 13 figures, accepted for publication in MNRA
Flat Symplectic Bundles of N-Extended Supergravities, Central Charges and Black-Hole Entropy
In these lectures we give a geometrical formulation of N-extended
supergravities which generalizes N=2 special geometry of N=2 theories. In all
these theories duality symmetries are related to the notion of "flat symplectic
bundles" and central charges may be defined as "sections" over these bundles.
Attractor points giving rise to "fixed scalars" of the horizon geometry and
Bekenstein-Hawking entropy formula for extremal black-holes are discussed in
some details.Comment: Based on lectures given by S. Ferrara at the 5th Winter School on
Mathematical Physics held at the Asia Pacific Center for Theoretical Physics,
Seul (Korea), February 199
TRANSBOUNDARY RENEWABLE RESOURCE MANAGEMENT: A DYNAMIC GAME WITH DIFFERING NONCOOPERATIVE PAYOFFS.
Recent conflicts over fish stocks, such as salmon and turbot, have revived public interest in the optimal management of transboundary renewable natural resources. Given that enforcement of binding contracts is often a major obstacle, dynamically consistent or self-enforcing contracting, as proposed by Vislie (1987), must be relied upon. A more general model is developed which recognizes that, in the absence of a cooperative agreement, two countries may enjoy differing economic payoffs. The predictions of the model are consistent with, and provide insights into, the particulars of recent disputes.Resource /Energy Economics and Policy,
Combination formoterol and budesonide as maintenance and reliever therapy versus combination inhaler maintenance for chronic asthma in adults and children.
BACKGROUND: Asthma is characterised by chronic inflammation of the airways and recurrent exacerbations with wheezing, chest tightness and cough. Treatment with inhaled steroids and bronchodilators often results in good control of symptoms, prevention of further morbidity and mortality and improved quality of life. Several steroids and beta2-agonists (long- and short-acting) as well as combinations of these treatments are available in a single inhaler to be used once or twice a day, with a separate inhaler for relief of symptoms when needed (for patients in Step three or higher, according to Global Initiative for Asthma (GINA) guidelines). Budesonide/formoterol is also licenced for use as maintenance and reliever therapy from a single inhaler (SiT; sometimes referred to as SMART therapy). SiT can be prescribed at a lower dose than other combination therapy because of the additional steroid doses being received as reliever therapy. It has been suggested that using SiT improves compliance and hence reduces symptoms and exacerbations, but it is unclear whether it increases side effects associated with the use of inhaled steroids. OBJECTIVES: To assess the efficacy and safety of budesonide/formoterol in a single inhaler (SiT) to be used for both maintenance and reliever therapy in asthma in comparison with maintenance treatment provided through combination inhalers with a higher maintenance steroid dose (either fluticasone/salmeterol or budesonide/formoterol), along with additional fast-acting beta2-agonists for relief of symptoms. SEARCH METHODS: We searched the Cochrane Airways Group Specialised Register of trials, online trial registries and drug company websites. The most recent search was conducted in November 2013. SELECTION CRITERIA: We included parallel-group, randomised controlled trials of at least 12 weeks' duration. Studies were included if they compared single-inhaler therapy with budesonide/formoterol (SiT) versus combination inhalers at a higher maintenance dose of steroids than was given in the SiT arm (either salmeterol/fluticasone or budesonide/formoterol). DATA COLLECTION AND ANALYSIS: We used standard methods expected by The Cochrane Collaboration. Primary outcomes were exacerbations requiring hospitalisation, exacerbations requiring oral corticosteroids and serious adverse events (including mortality). MAIN RESULTS: Four studies randomly assigning 9130 people with asthma were included; two were six-month double-blind studies, and two were 12-month open-label studies. No trials included children younger than age 12. Trials included more women than men, with mean age ranging from 38 to 45, and mean baseline steroid dose (inhaled beclomethasone (BDP) equivalent) from 636 to 888 ÎŒg. Mean baseline forced expiratory volume in one second (FEV1) percentage predicted was between 70% and 73% in three of the trials, and 96% in another. All studies were funded by AstraZeneca and were generally free from methodological biases, although the two open-label studies were rated as having high risk for blinding, and some evidence of selective outcome reporting was found. These possible sources of bias did not lead us to downgrade the quality of the evidence. The quantity of inhaled steroids, including puffs taken for relief from symptoms, was consistently lower for SiT than for the comparison groups.Separate data for exacerbations leading to hospitalisations, to emergency room (ER) visits or to a course of oral steroids could not be obtained. Compared with higher fixed-dose combination inhalers, fewer people using SiT had exacerbations requiring hospitalisation or a visit to the ER (odds ratio (OR) 0.72, 95% confidence interval (CI) 0.57 to 0.90; I(2) = 0%, P = 0.66), and fewer had exacerbations requiring a course of oral corticosteroids (OR 0.75, 95% CI 0.65 to 0.87; I(2) = 0%, P = 0.82). This translates to one less person admitted to hospital or visiting the ER (95% CI 0 to 2 fewer) and two fewer people needing oral steroids (95% CI 1 to 3 fewer) compared with fixed-dose combination treatment with a short-acting beta-agonist (SABA) reliever (per 100 treated over eight months). No statistical heterogeneity was observed in either outcome, and the evidence was rated of high quality. Although issues with blinding were evident in two of the studies, and one study recruited a less severe population, sensitivity analyses did not change the main results, so quality was not downgraded.We could not rule out the possibility that SiT increased rates of serious adverse events (OR 0.92, 95% CI 0.74 to 1.13; I(2) = 0%, P = 0.98; moderate-quality evidence, downgraded owing to imprecision).We were unable to say whether SiT improved results for several secondary outcomes (morning and evening peak expiratory flow (PEF), rescue medication use, symptoms scales), and in cases where results were significant, the effect sizes were not considered clinically meaningful (predose FEV1, nocturnal awakenings and quality of life). AUTHORS' CONCLUSIONS: SiT reduces the number of people having asthma exacerbations requiring oral steroids and the number requiring hospitalisation or an ER visit compared with fixed-dose combination inhalers. Evidence for serious adverse events was unclear. The mean daily dose of inhaled corticosteroids (ICS) in SiT, including the total dose administered with reliever use, was always lower than that of the other combination groups. This suggests that the flexibility in steroid administration that is possible with SiT might be more effective than a standard fixed-dose combination by increasing the dose only when needed and keeping it low during stable stages of the disease. Data for hospitalisations alone could not be obtained, and no studies have yet addressed this question in children younger than age 12
11-Dimensional Supergravity Compactified on Calabi-Yau Threefolds
We consider generic features of eleven dimensional supergravity compactified
down to five dimensions on an arbitrary Calabi-Yau threefold.Comment: TeX, harvmac, 8 pg
Finite-Size Effects and Operator Product Expansions in a CFT for d>2
The large momentum expansion for the inverse propagator of the auxiliary
field in the conformally invariant O(N) vector model is calculated
to leading order in 1/N, in a strip-like geometry with one finite dimension of
length for . Its leading terms are identified as contributions from
itself and the energy momentum tensor, in agreement with a
previous calculation based on conformal operator product expansions. It is
found that a non-trivial cancellation takes place by virtue of the gap
equation. The leading coefficient of the energy momentum tensor contribution is
shown to be related to the free energy density.Comment: 10 pages LaTeX 2 eps figures, minor changes in text. Revised version
to be published in Phys.Lett. B. email: [email protected]
[email protected]
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