Asymptotic Conditional Distribution of Exceedance Counts: Fragility Index with Different Margins

Let $\bm X=(X_1,...,X_d)$ be a random vector, whose components are not necessarily independent nor are they required to have identical distribution functions $F_1,...,F_d$. Denote by $N_s$ the number of exceedances among $X_1,...,X_d$ above a high threshold $s$. The fragility index, defined by $FI=\lim_{s\nearrow}E(N_s\mid N_s>0)$ if this limit exists, measures the asymptotic stability of the stochastic system $\bm X$ as the threshold increases. The system is called stable if $FI=1$ and fragile otherwise. In this paper we show that the asymptotic conditional distribution of exceedance counts (ACDEC) $p_k=\lim_{s\nearrow}P(N_s=k\mid N_s>0)$, $1\le k\le d$, exists, if the copula of $\bm X$ is in the domain of attraction of a multivariate extreme value distribution, and if $\lim_{s\nearrow}(1-F_i(s))/(1-F_\kappa(s))=\gamma_i\in[0,\infty)$ exists for $1\le i\le d$ and some $\kappa\in{1,...,d}$. This enables the computation of the FI corresponding to $\bm X$ and of the extended FI as well as of the asymptotic distribution of the exceedance cluster length also in that case, where the components of $\bm X$ are not identically distributed

A Threshold Model of Real US GDP and the Problem of Constructing Confidence Intervals in TAR Models

We estimate real U.S. GDP growth as a threshold autoregressive process, and construct confidence intervals for the parameter estimates. However, there are various approaches that can be used in constructing the confidence intervals. Specifically, standard- t , bootstrap- t , and bootstrap-percentile confidence intervals are simulated for the slope coefficients and the estimated threshold. However, the results for the different methods have very different economic implications. We perform a Monte Carlo experiment to evaluate the various methods.Bootstrap GDP; Threshold Autoregression; Bootstrap Confidence Intervals

Excited Heavy Mesons Beyond Leading Order in the Heavy Quark Expansion

We examine the decays of excited heavy mesons, including the leading power corrections to the heavy quark limit. We find a new and natural explanation for the large deviation of the width of the $D_1(2420)$ from the heavy quark symmetry prediction. Our formalism leads to detailed predictions for the properties of the excited bottom mesons, some of which recently have been observed. Finally, we present a detailed analysis of the effect of power corrections and finite meson widths on the angular distributions which may be measured in heavy meson decays.Comment: Uses REVTeX, 19 pages, 6 EPS figures embedded with epsf.st

Subjective Patterns of Randomness and Choice: Some Consequences of Collective Responses

Any individual's response intended to be random should be as probable as any other. However, 3 experiments show that many people's independent responses depart from the expected chance distribution. Participants responding to instructions of chance and related concepts favor the available options unequally in a similar way. Consequently, in hide-and-seek games, hiders converge on certain locations and are thereby detected beyond chance by seekers who share their preferences. People agree on salient and on nonsalient options, both of which are preferred under different instructions and even in the absence of instructions. Group responses strongly correlate under diverse, even opposing (e.g., competitive and cooperative) directions. Apparently, common default tendencies, combining random and aesthetic choices, are only somewhat modified under specific instructions. Maximal agreement with others is obtained by implementing one's own aesthetic preferences. These results broadly replicate in one- and two-dimensional tasks. Implications of the findings, their possible roots, and their connection to constructs from, e.g., game theory and subjective-complexity research, are discussed

Active vision-based localization for robots in a home-tour scenario

Self-Localization is a crucial task for mobile robots. It is not only a requirement for auto navigation but also provides contextual information to support human robot interaction (HRI). In this paper we present an active vision-based localization method for integration in a complex robot system to work in human interaction scenarios (e.g. home-tour) in a real world apartment. The holistic features used are robust to illumination and structural changes in the scene. The system uses only a single pan-tilt camera shared between different vision applications running in parallel to reduce the number of sensors. Additional information from other modalities (like laser scanners) can be used, profiting of an integration into an existing system. The camera view can be actively adapted and the evaluation showed that different rooms can be discerned

Expected budget deficits and interest rate swap spreads - Evidence for France, Germany and Italy

This study analyses whether expected budget deficits have an impact on interest rate swap spreads in France, Germany and Italy. We use monthly deficit forecasts from financial market participants to take the forward-looking behaviour of financial markets into account. Results of a SUR estimation show no significant impact of expected deficits on swap spreads over the whole sample period (1994-2004). However, we find an increase in market discipline for Germany and France since the signing of the Stability and Growth Pact, and for Germany also since the start of European monetary union. --Budget deficits,interest rate swap spreads,EMU,Stability and Growth Pact

Requirement of endogenous tumor necrosis factor/cachectin for recovery from experimental peritonitis

By intrasplenic immunization we raised a rat mAb (mAb V1q; IgG2a, kappa) with a potent neutralizing activity against natural mouse TNF (1 microgram/ml mAb V1q/100 U/ml TNF). mAb V1q was used to study the role of endogenous TNF in experimental peritonitis induced by sublethal cecal ligation and puncture. mAb V1q persisted for over 5 days in the serum of mice injected with 100 micrograms of the antibody and, therefore, proved useful for in vivo experiments. As little as 20 micrograms mAb V1q/mouse prevented lethal shock of the animals by 400 micrograms LPS/mouse. In sublethal cecal ligation and puncture i.p. injection of mAb V1q directly and up to 8 h after induction of experimental peritonitis lead to death of the animals within 1 to 3 days. The lethal effect of mAb V1q was compensated by injection of recombinant mouse TNF. Similar mAb V1q effects as in immunocompetent mice were shown in severe combined immune deficiency mice deficient of mature functional B and T cells. Taken together, these data suggest that during the early phase of peritonitis endogenous TNF may stimulate nonlymphoid cells such as granulocytes, macrophages, platelets, and fibroblasts to ingest bacteria and to localize inflammation, respectively. These beneficial effects of TNF may determine survival. Thus, our data may have implications for the therapeutic management of a beginning peritonitis

Biodiversity, management and utilization of West African fishes

Biodiversity, Nature conservation, Fishery management, Fishery resources, Fish, WorldFish Center Contrib. No. 1718, Africa, west,

System design and performance of earth/lunar horizon sensor BEC project 3744

An infrared horizon sensor system has been designed which is capable of searching over a wide field for the edges of a planet and, upon locating such edges, stations itself in a position which provides signals which identify the local vertical to the planet. In this fixed attitude it requires no continuous mechanical movement and operates with a minimum utilization of power. The system is thus capable of providing a high degree of accuracy when used for local vertical determination in orbits around the earth, the moon, or other planets. A detailed description of the design and operating features of the horizon scanner is given and the evaluation test data which have been completed are presented