Indoor scene recognition by a mobile robot through adaptive object detection

Mobile robotics has achieved notable progress, however, to increase the complexity of the tasks that mobile robots can perform in natural environments, we need to provide them with a greater semantic understanding of their surrounding. In particular, identifying indoor scenes, such as an Office or a Kitchen, is a highly valuable perceptual ability for an indoor mobile robot, and in this paper we propose a new technique to achieve this goal. As a distinguishing feature, we use common objects, such as Doors or furniture, as a key intermediate representation to recognize indoor scenes. We frame our method as a generative probabilistic hierarchical model, where we use object category classifiers to associate low-level visual features to objects, and contextual relations to associate objects to scenes. The inherent semantic interpretation of common objects allows us to use rich sources of online data to populate the probabilistic terms of our model. In contrast to alternative computer vision based methods, we boost performance by exploiting the embedded and dynamic nature of a mobile robot. In particular, we increase detection accuracy and efficiency by using a 3D range sensor that allows us to implement a focus of attention mechanism based on geometric and structural information. Furthermore, we use concepts from information theory to propose an adaptive scheme that limits computational load by selectively guiding the search for informative objects. The operation of this scheme is facilitated by the dynamic nature of a mobile robot that is constantly changing its field of view. We test our approach using real data captured by a mobile robot navigating in Office and home environments. Our results indicate that the proposed approach outperforms several state-of-the-art techniques for scene recognition.     

Increasing the accuracy of structure function based thermal material parameter measurements

The Structure functions based evaluation of the thermal transient measurements is now a broadly accepted way for the characterization of the time dependent behavior of the heat flow path. The usual way of generating structure functions considers one main heat flow path. By using a large mathematical tool set it generates for this path the Rth-Cth map of the structure. This enables easy detection of partial thermal resistances in the heat flow path, with which we can determine the values of, e.g,. interface thermal resistances, local effective thermal conductivity values, etc. The accuracy that we can obtain with this material parameter measuring methodology is in the order of 20%. In this paper, we present a methodology that enhances the accuracy of the structure function based material parameter measuring methods. In this procedure, on one hand, we measure the thermal transients for the system to be characterized and on the other hand we measure the "parasitic" heat flow path, that influences our measurement. The material parameters are calculated by appropriately modifying the measured results with the data of the parasitic heat flow path. In this paper, we present this methodology with mathematical details, and prove it with measured results.     

Isosbestic Points in the Spectral Function of Correlated Electrons

We investigate the properties of the spectral function A(ω,U) of correlated electrons within the Hubbard model and dynamical mean-field theory. Curves of A(ω,U) versus ω for different values of the interaction U are found to intersect near the band-edges of the non-interacting system. For a wide range of U the crossing points are located within a sharply confined region. The precise location of these “isosbestic points” depends on details of the non-interacting band structure. Isosbestic points of dynamic quantities therefore provide valuable insights into microscopic energy scales of correlated systems. This paper is dedicated to Hilbert von L?hneysen on the occasion of his 60th birthday.     

Odontogenic epithelium induces similar molecular responses in chick and mouse mandibular mesenchyme

Previous observations have shown that, during the initiation phase of odontogenesis, signals from mouse odontogenic epithelium can elicit teeth in non-odontogenic but neural crest-derived mesenchyme isolated from ectopic sites including chick mandibular mesenchyme. In the present study the formation of ectopic tooth buds and dental mesenchyme in chick mandibular mesenchyme was examined using heterospecific recombinations between E11 mouse odontogenic epithelium and stage 23 chick lateral mandibular mesenchyme. Both morphological criteria and chick-specific probes for Msx-1, Msx-2, and Bmp-4 mRNAs were used as markers for early dental mesenchyme. Our results demonstrated that interactions of mouse odontogenic epithelium with chick mandibular mesenchyme induce early changes in the chick mandibular mesenchyme including the appearance of a translucent zone, cell proliferation, and induction of expression of Msx-1, Msx-2, and Bmp-4, which have been shown to be associated with the formation of dental mesenchyme. In addition, tooth bud-like structures that resemble E13 tooth buds in vivo both morphologically and in their patterns of gene expression formed after 6 days in the heterospecific recombinations. The tooth bud-like structures consist of invaginated mouse mandibular epithelium and condensed chick mandibular mesenchyme expressing high levels of Msx-1 and Bmp-4, but undetectable levels of Msx-2. Unlike the induction of Msx-1, Msx-2, and Bmp-4 in the underlying mesenchyme, which is specific for signals derived from odontogenic epithelium, the induction of a translucent zone and cellular proliferation in the underlying mesenchyme may be related to the growth-promoting potential of embryonic epithelia and not be specific to signals derived from the odontogenic epithelium. Similar to mouse odontogenic epithelium, agarose beads soaked in recombinant BMP-4 induced a translucent zone, cellular proliferation, and expression of Msx-1, Msx-2, and Bmp-4 in chick mandibular mesenchyme after 24 hours. These observations together showed that avian mandibular mesenchyme has odontogenic potential that is expressed upon interactions with inductive signals from mouse odontogenic epithelium. Similar to odontogenesis in vivo, formation of dental mesenchyme in chick mandibular mesenchyme is mediated by the activation of Msx-1, Msx-2, and Bmp-4.     

Multiparameter optimization of inverse filtering algorithms

This paper investigates inverse filtering of transient signals. The problem is ill-conditioned, which means that a small uncertainty in the measurement causes large deviations in the reconstructed signal. This amplified noise has to be suppressed at the price of bias in the estimation. The most difficult task is to find the optimal degree of noise reduction. Deconvolution algorithms are usually controlled by one or a few parameters. Several algorithms can be found in the literature to find the best setting of inverse filtering methods; however, usually methods with only one free parameter are handled. In this paper, an algorithm is proposed to optimize several parameters, on the basis of a spectral model. Multiparameter inverse filtering methods have the advantage that they can be better adapted to the measurement system, and to the noise and signal to be measured. The superiority of the proposed optimization method is demonstrated both on simulated and on experimental data     

Specification for common IEEE styles

Our premise is that a researcher should be able to use his or her time doing research, and not fighting with a text formatter. Modern formatters have macro capability. If the proper macros are written, the text formatting for all IEEE publications may be accomplished automatically. We propose that proponents of various text-processing systems write macro packages for their own systems. The scientific community would benefit greatly. One example is provided for users of the LATEX2_ϵ system. It is available at http://www-isl.stanford.edu/ieee/ or at the ftp site ftp://isl.stanford.edu/pub/ieee/. A similar macro package is being developed for users of Microsoft Word, and can be found at the world-wide-web addresses given in the Conclusion     

Optimal FIR and IIR Hilbert transformer design via LS and minimaxfitting

A method for the design of both finite impulse response (FIR) and infinite impulse resonant (IIR) digital Hilbert transformers, based on a parameter estimation method for linear systems, is presented. The first approximation is performed in a least-squares (LS) sense in the complex domain. An iterative extension of the algorithm is also presented. It results in an approximation in a minimax (Chebyshev) sense and is also in the complex domain. The procedures described can be used for the design of digital filters other than Hilbert transformers since the desired frequency response is given point by point     

Crest-factor minimization using nonlinear Chebyshev approximationmethods

Low crest-factor of excitation and response signals is desirable in transfer function measurements, since this allows the maximization of the signal-to-noise ratios (SNRs) for given allowable amplitude ranges of the signals. The authors present a new crest-factor minimization algorithm for periodic signals with prescribed power spectrum. The algorithm is based on approximation of the nondifferentiable Chebyshev (minimax) norm by l_p-norms with increasing values of p, and the calculations are accelerated by using FFTs. Several signals related by linear systems can also be compressed simultaneously. The resulting crest-factors are significantly better than those provided by earlier methods. It is shown that the peak value of a signal can be further decreased by allowing some extra energy at additional frequencies     

Antiproliferative and Pro-Apoptotic Effect of Novel Nitro-Substituted Hydroxynaphthanilides on Human Cancer Cell Lines

Ring-substituted hydroxynaphthanilides are considered as cyclic analogues of salicylanilides, compounds possessing a wide range of pharmacological activities, including promising anticancer properties. The aim of this study was to evaluate the potential anticancer effect of novel nitro-substituted hydroxynaphthanilides with a special focus on structure-activity relationships. The antiproliferative effect was assessed by Water Soluble Tetrazolium Salts-1 (WST-1) assay, and cytotoxicity was evaluated via dye exclusion test. Flow cytometry was used for cell cycle analysis and detection of apoptosis using Annexin V-FITC/PI assay. Protein expression was estimated by Western blotting. Our data indicate that the potential to cause the antiproliferative effect increases with the shift of the nitro substituent from the ortho- to the para-position. The most potent compounds, 3-hydroxy-N-(3-nitrophenyl)naphthalene-2-carboxamide (2), and 2-hydroxy-N-(4-nitrophenyl)-naphthalene-1-carboxamide (6) showed antiproliferative activity against THP-1 and MCF-7 cancer cells without affecting the proliferation of 3T3-L1 non-tumour cells. Compounds 2 and 6 induced the accumulation of THP-1 and MCF-7 cells in G1 phase associated with the downregulation of cyclin E1 protein levels, while the levels of cyclin B1 were not affected. Moreover, compound 2 was found to exert the pro-apoptotic effect on the THP-1 cells. These results suggest that hydroxynaphthanilides might represent a potential model structure for the development of novel anticancer agents.