Robust inference of trees

This paper is concerned with the reliable inference of optimal tree-approximations to the dependency structure of an unknown distribution generating data. The traditional approach to the problem measures the dependency strength between random variables by the index called mutual information. In this paper reliability is achieved by Walley's imprecise Dirichlet model, which generalizes Bayesian learning with Dirichlet priors. Adopting the imprecise Dirichlet model results in posterior interval expectation for mutual information, and in a set of plausible trees consistent with the data. Reliable inference about the actual tree is achieved by focusing on the substructure common to all the plausible trees. We develop an exact algorithm that infers the substructure in time O(m ⁴), m being the number of random variables. The new algorithm is applied to a set of data sampled from a known distribution. The method is shown to reliably infer edges of the actual tree even when the data are very scarce, unlike the traditional approach. Finally, we provide lower and upper credibility limits for mutual information under the imprecise Dirichlet model. These enable the previous developments to be extended to a full inferential method for trees.     

Location Models for Augmented Environments

In this paper we describe two projects on contextualized computer systems and audio augmented environments we are currently working on at the Fraunhofer Institutes FIT and IMK. In this paper we will only focus on the world models and the augmentation layer. Both projects are based on completely different technologies, and use different representation methods and interaction facilities. While in hippie users are moving with small laptop computers or wearable computers with a small visual display, in LISTEN users will have only a wireless headphone displaying spatially rendered sound-scenes. Correspondence to: J. Goβmann, Fraunhofer-IMK, Schloss Birlinghoven, D-53754 St Augustin, Germany.     

The Golden Section in Architectural Theory

The never-ending—but always young—discussion about the Golden Section in architecture never lacks a hint at Luca Pacioli and architectural theory. But what it always lacks is a thorough study of the Golden Section in architectural theory. This paper aims to present this analysis. Marcus Frings traces the Golden Section from the mathematical and rather theoretical character of Pacioli’s concept, the the treatises of Alberti, Serlio, and Palladio, to Adolf Zeising in the nineteenth century. and to theorist Matila Ghyka and the practitioners Ernst Neufert and Le Corbusier in the twentieth. In the latter’s writings and designs the Golden Section seems to play the role of a scholarly element which shows the master’s theoretical erudition, leading to contemporary architects such as Ricardo Bofill.     

Sampling and analysis of particulate matter by glow discharge atomic emission and mass spectrometries

The direct introduction of particulate matter into glow discharge atomic emission and mass spectrometry sources through a particle beam/momentum separator apparatus is described. Vacuum action through a narrow (0.0625 in. i.d.) stainless steel tube allows the introduction of discrete samples of NIST SRM 1648 urban particulate matter (UPM) and caffeine in powder form. Introduction of "ambient" airborne particulate matter is also possible. Particles passing through the aerodynamic momentum separator impinge on the heated (～200-250 °C) inner surface of the glow discharge plasma volume and are flash-vaporized. The resultant atoms/molecules are subjected to excitation/ionization collisions within the low-pressure (0.5-5 Torr of He or Ar) plasma, producing characteristic photon emission and/or signature ionic species. In this way, atomic emission and mass spectrometry identification of particle constituents is possible. Basic design aspects of the apparatus are presented, and demonstrations of atomic emission detection of the constituents in the NIST SRM illustrate the general characteristics of the approach. Transient atomic emission signals are captured for the introduction of preweighed, discrete samples, with the integrated areas used to construct analytical response curves. Limits of detection using this relatively simple atomic emission system are on the order of tens of nanograms for sample masses of ～50 μg. Mass spectrometric monitoring of introduced caffeine particles and a mixture of polycyclic aromatic hydrocarbons (PAHs) illustrates the ability of the glow discharge plasma to produce high-quality, library (electron impact) searchable mass spectra of molecular species while also yielding isotopic identification of elemental components of the UPM. Limits of detection for Fe in the NIST SRM are on the order of 175 ng of material, equivalent to ～7 ng of analyte Fe. It is believed that the small size, low power consumption, ease of operation, and multimode sampling capabilities (AES/MS) of the particle beam-glow discharge (PB-GD) apparatus hold promise for applications in continuous monitoring and discrete particle sampling.     

Optical Properties of Doped Antiferromagnets

We investigate the consequences of an incommensurate magnetic order in doped La_2–x Sr _x CuO₄ using dynamical mean-field theory for the effective single-band model. The high-energy optical transitions are due to high-energy excitations across large Mott–Hubbard gap, while low-energy excitations involve a pseudogap induced by the local spin order. The latter lead to a strong drop in the scattering rate at low , in qualitative agreement with the experimental data.     

Conditioned and unconditioned fear organized in the inferior colliculus are differentially sensitive to injections of muscimol into the basolateral nucleus of the amygdala.

Chemical stimulation of the inferior colliculus (IC) with semicarbazide--an inhibitor of the gamma aminobutyric acid synthesizing enzyme--functions as an unconditioned stimulus in the conditioned place aversion test (CPA), and electrolytic lesions of the basolateral amygdala (BLA) enhance the aversiveness of the IC stimulation. This study examined the effects of inactivation of the BLA with muscimol on the conditioned and unconditioned fear using semicarbazide injections into the IC of rats subjected to conditioned (CPA) or unconditioned (open field) fear tests. In both tests, the rats were injected with semicarbazide or saline into the IC and muscimol or saline into the BLA. Muscimol decreased the CPA and increased the unconditioned fear elicited by IC injections of semicarbazide. These findings indicate that distinct modulatory mechanisms in the BLA are recruited during the conditioned and unconditioned fear triggered by IC activation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Identification and approximation of queueing systems

A distance-measures approach to the problems of identification and approximation of queueing systems is presented. This approach combines ideas from statistical robustness, information-type measures, and parameter-continuity of stochastic processes.     

Refusal to eat in the elderly

Refusal to eat by the elderly, and subsequent malnutrition, occurs in both institutional and community settings. Causes include physiologic changes associated with aging, mental disorders such as dementia and depression, and medical, social, and environmental factors. Treatment approaches call for management of these causes while considering the roles that medicine, ethics, and culture play in the process.     

Dermatofibrosarcoma protuberans and the Bednar tumor: treatment in the pediatric population

Dermatofibrosarcoma protuberans (DFSP) is a low-intermediate-grade cutaneous sarcoma that has a marked propensity for local recurrence after excision. The Bednar variant of this tumor is even less common and is distinguished histologically by the dispersal of melanin containing cells in an otherwise typical DFSP. Both are considered to be tumors of the third and forth decades of life, but both DFSP and the Bednar variant have been described in children. Until this report of a congenital Bednar tumor, only the DFSP has also been described in the neonate. The histopathology and surgical management of DFSP and Bednar tumors are outlined with emphasis on reported experience in the pediatric population. The surgical management of these lesions in children is based on numerous series in adults and the limited pediatric experience. The recommended treatment is wide excision with 3-cm margins of visibly uninvolved tissue and inclusion of superficial fascia.