We study the rates at which optimal estimators in the sample average approximation approach converge to their deterministic counterparts in the almost sure sense and in mean. To be able to quantify ...these rates, we consider the law of the iterated logarithm in a Banach space setting and first establish under relatively mild assumptions almost sure convergence rates for the approximating objective functions, which can then be transferred to the estimators for optimal values and solutions of the approximated problem. By exploiting a characterisation of the law of the iterated logarithm in Banach spaces, we are further able to derive under the same assumptions that the estimators also converge in mean, at a rate which essentially coincides with the one in the almost sure sense. This, in turn, allows to quantify the asymptotic bias of optimal estimators as well as to draw conclusive insights on their mean squared error and on the estimators for the optimality gap. Finally, we address the notion of convergence in probability to derive rates in probability for the deviation of optimal estimators and (weak) rates of error probabilities without imposing strong conditions on exponential moments. We discuss the possibility to construct confidence sets for the optimal values and solutions from our obtained results and provide a numerical illustration of the most relevant findings.
In the last few years, the first theoretical foundations for replicating portfolios - probably the most prevailing technique for risk capital calculation in life insurance - have been given in a ...series of papers by Beutner, Pelsser and Schweizer. In these papers, the asymptotic behaviour of replicating portfolios concerning the approximation of the terminal value (TVL) and the fair value distribution of the liabilities (FVL) has been investigated in detail. We complement this line of research by providing results on approximations based on a finite number of replicating instruments. We do so by providing the link between the approximation error of the TVL distribution, the FVL distribution and the error in the resulting risk capital figure, either value at risk or some coherent risk measure. We further allow for a variety of practically relevant formulations of the replication problem, including cash flow matching approaches. In contrast to the existing literature, all our results apply to approaches both under the risk-neutral and the real-world measure. Our strongest bounds are due to the observation that in discrete time, the measure change from the real-world to the risk-neutral measure can be both bounded below and above by a suitable constant in the first period.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Die vorliegende Arbeit beschäftigt sich mit der Kompensation frequenzabhängiger Fehler, die in der Strommessung mit Messwiderständen durch parasitäre Einflüsse auftreten. Dazu werden die Amplituden- ...und Phasengänge unterschiedlicher Messwiderstände aus einem Versuchsstand gemessen und ausgewertet. Anhand dessen wird eine alternative Kompensationsmethode anstatt der Übertragungsfunktion des Ersatzschaltbildes eines Messwiderstandes entwickelt. Es erfolgt eine Verifizierung der Methode mit Hilfe eines Versuchsstandes zur Bestimmung der magnetischen Eigenschaften von Blechproben.
We assessed the incidence of early recurrent ischemic stroke in stroke patients treated with intravenous tissue-type plasminogen activator (tPA) and the temporal pattern of its occurrence compared ...with symptomatic intracranial hemorrhage (ICH).
Prospectively collected, population-based data for 341 consecutive acute stroke patients (62% men; mean age, 66 years) treated with tPA according to the National Institute of Neurological Disorders and Stroke study protocol at 8 medical centers in Switzerland (3 academic and 5 community) between January 2001 and November 2004 were retrospectively analyzed. The primary outcome measure was neurological deterioration > or = 4 points on the National Institutes of Health Stroke Scale occurring within 24 hours of tPA treatment and caused either by recurrent ischemic stroke (defined as the occurrence of new neurological symptoms suggesting involvement of initially unaffected vascular territories and evidence of corresponding ischemic lesions on cranial computed tomography scans, in the absence of ICH) or by ICH. Early recurrent ischemic stroke was diagnosed in 2 patients (0.59%; 95% confidence interval, 0.07% to 2.10%) and symptomatic ICH in 15 patients (4.40%; 95% confidence interval, 2.48% to 7.15%). Both recurrent ischemic strokes occurred during thrombolysis, whereas symptomatic ICHs occurred 2 to 22 hours after termination of tPA infusion.
Recurrent ischemic stroke is a rare cause of early neurological deterioration in acute stroke patients undergoing intravenous thrombolysis, with a different temporal pattern compared with that of symptomatic ICH.
To better understand the molecular programs of normal and abnormal genital development, clear-cut definition of androgen-dependent gene expression patterns, without the influence of genotype (46, XX ...vs. 46, XY), is warranted. Previously, we have identified global gene expression profiles in genital-derived fibroblasts that differ between 46, XY males and 46, XY females with complete androgen insensitivity syndrome (CAIS) due to inactivating mutations of the androgen receptor (AR). While these differences could be due to cell autonomous changes in gene expression induced by androgen programming, recent work suggests they could also be influenced by the location from which the fibroblasts were harvested (topology). To minimize the influence of topology, we compared gene expression patterns of fibroblasts derived from identical urogenital anlagen: the scrotum in normally virilized 46, XY males and the labia majora from completely feminized 46, XY individuals with CAIS.
612 transcripts representing 440 unique genes differed significantly in expression levels between scrotum and CAIS labia majora, suggesting the effects of androgen programming. While some genes coincided with those we had identified previously (TBX3, IGFBP5, EGFR, CSPG2), a significant number did not, implying that topology had influenced gene expression in our previous experiments. Supervised clustering of gene expression data derived from a large set of fibroblast cultures from individuals with partial AIS revealed that the new, topology controlled data set better classified the specimens.
Inactivating mutations of the AR, in themselves, appear to induce lasting changes in gene expression in cultured fibroblasts, independent of topology and genotype. Genes identified are likely to be relevant candidates to decipher androgen-dependent normal and abnormal genital development.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Participating life insurance contracts allow the policyholder to participate in the annual return of a reference portfolio. Additionally, they are often equipped with an annual (cliquet-style) return ...guarantee. The current low interest rate environment has again refreshed the discussion on risk management and fair valuation of such embedded options. While this problem is typically discussed from the viewpoint of a single contract or a homogeneous* insurance portfolio, contracts are, in practice, managed within a heterogeneous insurance portfolio. Their valuation must then - unlike the case of asset portfolios - take account of portfolio effects: Their premiums are invested in the same reference portfolio; the contracts interact by a joint reserve, individual surrender options and joint default risk of the policy sponsor. Here, we discuss the impact of portfolio effects on the fair valuation of insurance contracts jointly managed in (homogeneous and) heterogeneous life insurance portfolios. First, in a rather general setting, including stochastic interest rates, we consider the case that otherwise homogeneous contracts interact due to the default risk of the policy sponsor. Second, and more importantly, we then also consider the case when policies are allowed to differ in further aspects like the guaranteed rate or time to maturity. We also provide an extensive numerical example for further analysis.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Purpose
Mutations in the
NR5A1
gene, encoding the transcription factor Steroidogenic Factor-1, are associated with a highly variable genital phenotype in patients with 46,XY differences of sex ...development (DSD). Our objective was to analyse the pubertal development in 46,XY patients with
NR5A1
mutations by the evaluation of longitudinal clinical and hormonal data at pubertal age.
Methods
We retrospectively studied a cohort of 10 46,XY patients with a verified
NR5A1
mutation and describe clinical features including the external and internal genitalia, testicular volumes, Tanner stages and serum concentrations of LH, FSH, testosterone, AMH, and inhibin B during pubertal transition.
Results
Patients who first presented in early infancy due to ambiguous genitalia showed spontaneous virilization at pubertal age accompanied by a significant testosterone production despite the decreased gonadal volume. Patients with apparently female external genitalia at birth presented later in life at pubertal age either with signs of virilization and/or absence of female puberty. Testosterone levels were highly variable in this group. In all patients, gonadotropins were constantly in the upper reference range or elevated. Neither the extent of virilization at birth nor the presence of Müllerian structures reliably correlated with the degree of virilization during puberty.
Conclusion
Patients with
NR5A1
mutations regardless of phenotype at birth may demonstrate considerable virilization at puberty. Therefore, it is important to consider sex assignment carefully and avoid irreversible procedures during infancy.
Zusammenfassung
In diesem Beitrag wird
ein kapazitives Abstandsmesssystem mit neuartiger Auswerteelektronik
beschrieben, welches nach dem Prinzip der
Amplitudenmodulation arbeitet und mehrfach ...differenziell ausgewertet
wird. Durch die Verwendung differenzieller Sensoren wird
der Einfluss der Kapazität vom Messobjekt zum Bezugspotential kompensiert
und im Vergleich zu üblichen kapazitiven Messsystemen eine deutliche
Erhöhung der Störsicherheit gegenüber Potentialänderungen
des Messobjekts erreicht. Die Auswerteelektronik ist
für besonders hohe Trägerfrequenzen konzipiert,
wodurch der Einfluss elektromagnetischer Störungen bis in den
einstelligen MHz-Bereich reduziert
wird. Durch Synchronisation können beliebig viele
Einzelmesssysteme zu einem störsicheren Mehrachsmesssystem kombiniert
werden, welches vor allem den hohen Anforderungen in der
aktiven Magnetlagertechnik gerecht wird.
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