Asymptotics of high order noise corrections

We consider an evolution operator for a discrete Langevin equation with a strongly hyperbolic classical dynamics and noise with finite moments. Using a perturbative expansion of the evolution operator we calculate high order corrections to its trace in the case of a quartic map and Gaussian noise. The leading contributions come from the period one orbits of the map. The asymptotic behaviour is investigated and is found to be independent up to a multiplicative constant of the distribution of noise.Comment: 5 pages, 6 figures, submitted to J. Stat. Phy

Noise corrections to stochastic trace formulas

We review studies of an evolution operator L for a discrete Langevin equation with a strongly hyperbolic classical dynamics and a Gaussian noise. The leading eigenvalue of L yields a physically measurable property of the dynamical system, the escape rate from the repeller. The spectrum of the evolution operator L in the weak noise limit can be computed in several ways. A method using a local matrix representation of the operator allows to push the corrections to the escape rate up to order eight in the noise expansion parameter. These corrections then appear to form a divergent series. Actually, via a cumulant expansion, they relate to analogous divergent series for other quantities, the traces of the evolution operators L^n. Using an integral representation of the evolution operator L, we then investigate the high order corrections to the latter traces. Their asymptotic behavior is found to be controlled by sub-dominant saddle points previously neglected in the perturbative expansion, and to be ultimately described by a kind of trace formula.Comment: 21 pages, 4 figures,corrected typo

The evolution and benefit of device therapy in patients listed for heart transplant

Aims: The latest 2015 ESC Guidelines on the prevention of sudden cardiac death make a Class IIa recommendation for ICD implantation in patients listed for heart transplantation. This recommendation was based on expert consensus in view of the sparsity of data. Methods and results: All patients listed for heart transplantation at the University Hospitals of Leuven from 2002 until 2014 were studied retrospectively. Exclusion criteria were age <16 years, cardiac disease other than ischaemic or dilated cardiomyopathy and re-transplantation. A total of 286 patients were included, of which 140 (49.0%) received an ICD. There was a historical increase of the time on the waiting list before transplantation (P < 0.001) together with an increase of the use of ICDs (P < 0.001) and left ventricular assist devices (LVADs) (P < 0.001). The proportion of patients reaching heart transplant remained unchanged (P = 0.700). The annual appropriate shock rate in patients with ICD was 28.0%/y on the active waiting list. Patients with ICD showed a trend to improved survival (P = 0.070). Independent predictors of mortality or removal from the transplant list because of clinical deterioration were the need for LVAD (HR 4.38, 95%CI 2.11-9.01), a history of stroke (HR 2.95, 95%CI 1.61-5.40), older age (HR 1.03, 95%CI 1.01-1.05) and a worse renal function (HR 1.15, 95%CI 1.00-1.33). Conclusion: The time on the waiting list for heart transplantation significantly increased together with an increased use of device therapy in this population. The proportion of patients reaching transplant remained unchanged. This patient group is prone to life-threatening arrhythmias and the use of an ICD may improve survival.status: publishe

Incidence of appropriate therapy after replacement of an uneventful first ICD

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Evolution in ICD implantation an effect on appropriate therapy rates

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The incidence of appropriate therapy after replacement of an uneventful first ICD

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Impaired adipose tissue development in mice with inactivation of placental growth factor function

Placental growth factor (PlGF)-deficient (PlGF-/-) and wild-type mice were kept on a standard-fat or high-fat diet for 15 weeks. With the standard-fat diet, the body weights of PlGF-/- and wild-type mice were comparable, whereas the combined weight of subcutaneous and gonadal adipose tissues was lower in PlGF-/- mice (P = 0.02). With the high-fat diet, PlGF-/- mice had a lower body weight (P < 0.05) and less total subcutaneous plus gonadal adipose tissue (P < 0.0001). Blood vessel size was lower in gonadal adipose tissue of PlGF-/- mice with both the standard-fat and high-fat diet (P < 0.05). Blood vessel density, normalized to adipocyte number, was significantly lower in subcutaneous adipose tissue of PlGF-/- mice fed the high-fat diet (P < 0.01). De novo adipose tissue development in nude mice injected with 3T3-F442A preadipocytes was reduced (P < 0.005) by administration of a PlGF-neutralizing antibody. Bone marrow transplantation from wild-type or PlGF-/- mice to wild-type or PlGF-/- recipient mice revealed significantly lower blood vessel density in PlGF-/- recipient mice without an effect on adipose tissue growth. Thus, in murine models of diet-induced obesity, inactivation of PlGF impairs adipose tissue development, at least in part as a result of reduced angiogenesis.status: publishe

The effect of inappropriate ICD therapy on mortality is cause dependent

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