Hierarchical GTM: constructing localized non-linear projection manifolds in a principled way

It has been argued that a single two-dimensional visualization plot may not be sufficient to capture all of the interesting aspects of complex data sets, and therefore a hierarchical visualization system is desirable. In this paper we extend an existing locally linear hierarchical visualization system PhiVis ¸iteBishop98a in several directions: bf(1) We allow for em non-linear projection manifolds. The basic building block is the Generative Topographic Mapping (GTM). bf(2) We introduce a general formulation of hierarchical probabilistic models consisting of local probabilistic models organized in a hierarchical tree. General training equations are derived, regardless of the position of the model in the tree. bf(3) Using tools from differential geometry we derive expressions for local directional curvatures of the projection manifold. Like PhiVis, our system is statistically principled and is built interactively in a top-down fashion using the EM algorithm. It enables the user to interactively highlight those data in the ancestor visualization plots which are captured by a child model. We also incorporate into our system a hierarchical, locally selective representation of magnification factors and directional curvatures of the projection manifolds. Such information is important for further refinement of the hierarchical visualization plot, as well as for controlling the amount of regularization imposed on the local models. We demonstrate the principle of the approach on a toy data set and apply our system to two more complex 12- and 18-dimensional data sets.

Constructing localized non-linear projection manifolds in a principled way:hierarchical generative topographic mapping

It has been argued that a single two-dimensional visualization plot may not be sufficient to capture all of the interesting aspects of complex data sets, and therefore a hierarchical visualization system is desirable. In this paper we extend an existing locally linear hierarchical visualization system PhiVis (Bishop98a) in several directions: 1. We allow for em non-linear projection manifolds. The basic building block is the Generative Topographic Mapping. 2. We introduce a general formulation of hierarchical probabilistic models consisting of local probabilistic models organized in a hierarchical tree. General training equations are derived, regardless of the position of the model in the tree. 3. Using tools from differential geometry we derive expressions for local directionalcurvatures of the projection manifold. Like PhiVis, our system is statistically principled and is built interactively in a top-down fashion using the EM algorithm. It enables the user to interactively highlight those data in the parent visualization plot which are captured by a child model.We also incorporate into our system a hierarchical, locally selective representation of magnification factors and directional curvatures of the projection manifolds. Such information is important for further refinement of the hierarchical visualization plot, as well as for controlling the amount of regularization imposed on the local models. We demonstrate the principle of the approach on a toy data set andapply our system to two more complex 12- and 19-dimensional data sets.

The work situation and class position of Brazilian engineers

This thesis analyses the work situation and class position of Brazilian engineers through a Marxist perspective. The research is based on two case studies, one focused on a large German steel company based in Brazil and the other on a large Brazilian energy corporation. The fieldwork involved 114 interviews, with engineers from different hierarchical positions in these two companies. Data was also gathered through interviews with representatives from the companies, the Council of Engineering, the Engineering Education System and the Engineers Trade Unions. The findings show that the engineering profession in Brazil has shifted from its initial condition as a liberal profession to an organizational profession, with the country's industrial deployment. Both companies consider all salaried workers as employees, including managers. Hence they are subject to the company's general personnel policies. The multinational company controls labour more rigidly than the national company, as well as reserving its top positions for its home country's executives. Although no deskilling process was found, engineers of both companies performed simple work, which required less engineering knowledge than they had learned from school. Engineers have little autonomy, authority and participation in decision making and are subject to direct supervision, performance evaluation, time control, overtime work, productivity and to poor working conditions in the multinational company. The majority of the engineers supervised other workers without being in a managerial position. They found that to move into management, was a good way to improve their autonomy, authority, prestige, salary, status, power and professional pride. Despite ideological divisions between capital and labour, most of the engineers were unionised and saw unions as the right way to deal with the employer.

A hierarchical localization scheme for large scale underwater wireless sensor networks

In this paper, we study the localization problem in large-scale Underwater Wireless Sensor Networks (UWSNs). Unlike in the terrestrial positioning, the global positioning system (GPS) can not work efficiently underwater. The limited bandwidth, the severely impaired channel and the cost of underwater equipment all makes the localization problem very challenging. Most current localization schemes are not well suitable for deep underwater environment. We propose a hierarchical localization scheme to address the challenging problems. The new scheme mainly consists of four types of nodes, which are surface buoys, Detachable Elevator Transceivers (DETs), anchor nodes and ordinary nodes. Surface buoy is assumed to be equipped with GPS on the water surface. A DET is attached to a surface buoy and can rise and down to broadcast its position. The anchor nodes can compute their positions based on the position information from the DETs and the measurements of distance to the DETs. The hierarchical localization scheme is scalable, and can be used to make balances on the cost and localization accuracy. Initial simulation results show the advantages of our proposed scheme. © 2009 IEEE.

Neural Network Evidence for the Coupling of Presaccadic Visual Remapping to Predictive Eye Position Updating.

As we look around a scene, we perceive it as continuous and stable even though each saccadic eye movement changes the visual input to the retinas. How the brain achieves this perceptual stabilization is unknown, but a major hypothesis is that it relies on presaccadic remapping, a process in which neurons shift their visual sensitivity to a new location in the scene just before each saccade. This hypothesis is difficult to test in vivo because complete, selective inactivation of remapping is currently intractable. We tested it in silico with a hierarchical, sheet-based neural network model of the visual and oculomotor system. The model generated saccadic commands to move a video camera abruptly. Visual input from the camera and internal copies of the saccadic movement commands, or corollary discharge, converged at a map-level simulation of the frontal eye field (FEF), a primate brain area known to receive such inputs. FEF output was combined with eye position signals to yield a suitable coordinate frame for guiding arm movements of a robot. Our operational definition of perceptual stability was "useful stability," quantified as continuously accurate pointing to a visual object despite camera saccades. During training, the emergence of useful stability was correlated tightly with the emergence of presaccadic remapping in the FEF. Remapping depended on corollary discharge but its timing was synchronized to the updating of eye position. When coupled to predictive eye position signals, remapping served to stabilize the target representation for continuously accurate pointing. Graded inactivations of pathways in the model replicated, and helped to interpret, previous in vivo experiments. The results support the hypothesis that visual stability requires presaccadic remapping, provide explanations for the function and timing of remapping, and offer testable hypotheses for in vivo studies. We conclude that remapping allows for seamless coordinate frame transformations and quick actions despite visual afferent lags. With visual remapping in place for behavior, it may be exploited for perceptual continuity.

Effects of prone and supine position on oxygenation and inflammatory mediator in a hydrochloric acid-induced lung dysfunction in rats

PURPOSE: To compare the effectiveness of mechanical ventilation of supine versus prone position in hydrochloric acid (HCl)-induced lung dysfunction. METHODS: Twenty, adult, male, Wistar-EPM-1 rats were anesthetized and randomly grouped (n=5 animals per group) as follows: CS-MV (mechanical ventilation in supine position); CP-MV (mechanical ventilation in prone position); bilateral instillation of HCl and mechanical ventilation in supine position (HCl+S); and bilateral instillation of HCl and mechanical ventilation in prone position (HCl+P). All groups were ventilated for 180 minutes. The blood partial pressures of oxygen and carbon dioxide were measured in the time points 0 (zero; 10 minutes before lung injury for stabilization), and at the end of times acid injury, 60, 120 and 180 minutes of mechanical ventilation. At the end of experiment the animals were euthanized, and bronchoalveolar lavages (BALs) were taken to determine the contents of total proteins, inflammatory mediators, and lungs wet-to-dry ratios. RESULTS: In the HCl+P group the partial pressure of oxygen increased when compared with HCl+S (128.0±2.9 mmHg and 111.0±6.7 mmHg, respectively) within 60 minutes. TNF-α levels in BAL do not differ significantly in the HCl+P group (516.0±5.9 pg/mL), and the HCl+S (513.0±10.6 pg/mL). CONCLUSION: The use of prone position improved oxygenation, but did not reduce TNF-α in BAL upon lung dysfunction induced by HCl.

Ergonomic Aspects Related to Surgeon Position in Laparoscopic Radical Prostatectomy

Purpose: The aim is to evaluate the level of inclination of the surgeon's spinal column (ISSC) while performing laparoscopic radical prostatectomy (LRP) when using one trocar on each side of the patient abdomen (""torero"" position) in two scenarios: With and without a thin head supporter adapted to the table. Materials and Methods: Based on trigonometric principles, we elaborated a formula to calculate the ISSC for a determined surgeon and surgical table while performing LRP in the torero position. The parameters considered were the width of the surgical table (m), the distance between the surgeon's anterior superior iliac spines (q), and the distance from the central point between the surgeon's anterior superior iliac spines to the surgeon's head (h). We used the formula alpha = 90 degree-cos(-1)(b/h) (where b = q/2 + m/2) in an Excel sheet to calculate the angle of inclination of the surgeon's spinal column. We applied the measures of 12 surgeons with different biotypes of our staff to calculate the ISSC with and without the thin head supporter. Results: The use of a thin head supporter reduced the mean ISCC in the torero position from 36.1 +/- 3.73 degrees (range 31.3 to 49.8 degrees) to 22.1 +/- 4.9 degrees (range 18.7 to 32.9 degrees), which corresponds to a reduction of 38.8% in the mean angle of inclination. This difference was statistically significant (P < 0.001). Conclusion: The use of a thin head supporter adapted to the surgical table objectively reduces lateral inclination of the surgeon's spinal column in the torero position, making LRP a more comfortable procedure.

DESCRIPTION OF ADULTS AND NYMPH, AND REDESCRIPTION OF THE LARVA, OF ORNITHODOROS MARINKELLEI (ACARI: ARGASIDAE), WITH DATA ON ITS PHYLOGENETIC POSITION

The argasid tick Ornithodoros marinkellei Kohls, Clifford, and Jones, 1969 was described 4 decades ago based on larval specimens collected from bats (Pteronotus spp.) in Colombia and Panama. Thereafter, larval O. marinkellei parasitizing bats were reported from Venezuela, Guyana, and Brazil. Herein, we describe the adults and nymph, and redescribe the larva of O. marinkellei based on specimens recently collected in the western Brazilian Amazon region. In contrast to all other known adult argasids, the idiosoma of both males and females of O. marinkellei is covered with sclerotized plaques. The idiosoma of the nymph of O. marinkellei is entirely micromamillated, and differs from the adults by the absence of plaques. The larva of O. marinkellei is morphologically similar to the larvae of the 2 other species belonging to the subgenus Subparmatus, i.e., Ornithodoros viguerasi Cooley and Kohls, 1941 and Ornithodoros mormoops Kohls, Clifford, and Jones, 1969. Because of the long and narrow dorsal plate, the larva of O. marinkellei is readily distinguished from O. viguerasi and O. mormoops. Comparison of our larvae from Brazil with O. marinkellei paratype specimens from Colombia confirmed their taxonomic identification. However, a few morphological differences, particularly in the size of the gnathosoma, were observed. Further studies are necessary to clarify whether O. marinkellei is a complex of different species, or a single species represented by morphologically polymorphic, and geographically distinct populations. Partial mitochondrial 16S rDNA gene sequences were generated for O. marinkellei specimens from Brazil, and compared with available homologous sequences in GenBank. Phylogenetic analyses revealed O. marinkellei to be distinct from the remaining argasid species available in GenBank, including other bat-associated tick species that are found in sympatry with O. marinkellei in the Neotropical region.

Changes in temporomandibular joint disc position and form following Herbst and fixed orthodontic treatment

Objective: To determine the changes in the position and form of the temporomandibular joint articular disc in adolescents with Class II division 1 malocclusion and mandibular retrognathism treated with the Herbst appliance (phase I) and fixed orthodontic appliance (phase II). Materials and Methods: Thirty-two consecutive adolescents went through phase I of treatment and 23 completed phase II. The temporomandibular joints were evaluated qualitatively by means of magnetic resonance images at the beginning of treatment (T1), during phase I (T2), at the end of phase I (T3), and at the end of phase II (T4). Results: Significant changes in disc position were not observed with the mouth closed between T1 X T3 (P = .317), T3 X T4 (P = .287), or T1 X T4 (P = .261). At T2, on average, the disc was positioned regressively. With the mouth open, no difference was observed between T1 X T3 (P = .223) or T1 X T4 (P = .082). We did observe a significant difference between T3 X T4 (P < .05). Significant changes in the disc form were found with the mouth closed between T1 X T2 (P < .001) and T2 X T3 (P < .001). Conclusions: At the end of the two-phase treatment, in general terms, the position and form of the initial articular discs were maintained; however, in some temporomandibular joints some seemingly adverse effects were observed at T4. (Angle Orthod. 2010;80:843-852.)

Phylogenetic position of the acariform mites: sensitivity to homology assessment under total evidence

Background: Mites (Acari) have traditionally been treated as monophyletic, albeit composed of two major lineages: Acariformes and Parasitiformes. Yet recent studies based on morphology, molecular data, or combinations thereof, have increasingly drawn their monophyly into question. Furthermore, the usually basal (molecular) position of one or both mite lineages among the chelicerates is in conflict to their morphology, and to the widely accepted view that mites are close relatives of Ricinulei. Results: The phylogenetic position of the acariform mites is examined through employing SSU, partial LSU sequences, and morphology from 91 chelicerate extant terminals (forty Acariformes). In a static homology framework, molecular sequences were aligned using their secondary structure as guide, whereby regions of ambiguous alignment were discarded, and pre-aligned sequences analyzed under parsimony and different mixed models in a Bayesian inference. Parsimony and Bayesian analyses led to trees largely congruent concerning infraordinal, well-supported branches, but with low support for inter-ordinal relationships. An exception is Solifugae + Acariformes (P. P = 100%, J. = 0.91). In a dynamic homology framework, two analyses were run: a standard POY analysis and an analysis constrained by secondary structure. Both analyses led to largely congruent trees; supporting a (Palpigradi (Solifugae Acariformes)) clade and Ricinulei as sister group of Tetrapulmonata with the topology (Ricinulei (Amblypygi (Uropygi Araneae))). Combined analysis with two different morphological data matrices were run in order to evaluate the impact of constraining the analysis on the recovered topology when employing secondary structure as a guide for homology establishment. The constrained combined analysis yielded two topologies similar to the exclusively molecular analysis for both morphological matrices, except for the recovery of Pedipalpi instead of the (Uropygi Araneae) clade. The standard (direct optimization) POY analysis, however, led to the recovery of trees differing in the absence of the otherwise well-supported group Solifugae + Acariformes. Conclusions: Previous studies combining ribosomal sequences and morphology often recovered topologies similar to purely morphological analyses of Chelicerata. The apparent stability of certain clades not recovered here, like Haplocnemata and Acari, is regarded as a byproduct of the way the molecular homology was previously established using the instrumentalist approach implemented in POY. Constraining the analysis by a priori homology assessment is defended here as a way of maintaining the severity of the test when adding new data to the analysis. Although the strength of the method advocated here is keeping phylogenetic information from regions usually discarded in an exclusively static homology framework; it still has the inconvenience of being uninformative on the effect of alignment ambiguity on resampling methods of clade support estimation. Finally, putative morphological apomorphies of Solifugae + Acariformes are the reduction of the proximal cheliceral podomere, medial abutting of the leg coxae, loss of sperm nuclear membrane, and presence of differentiated germinative and secretory regions in the testis delivering their products into a common lumen.

Position-dependent noncommutativity in quantum mechanics

The model of the position-dependent noncommutativity in quantum mechanics is proposed. We start with given commutation relations between the operators of coordinates [(x) over cap (i), (x) over cap (j)] = omega(ij) ((x) over cap), and construct the complete algebra of commutation relations, including the operators of momenta. The constructed algebra is a deformation of a standard Heisenberg algebra and obeys the Jacobi identity. The key point of our construction is a proposed first-order Lagrangian, which after quantization reproduces the desired commutation relations. Also we study the possibility to localize the noncommutativity.

TAXONOMIC POSITION OF GUIRATINGIA MENDESI (MEGADESMIDAE) AND THE EVOLUTION OF PERMIAN ENDEMIC BIVALVE FAUNA OF THE PARANA BASIN, BRAZIL

The unusual bivalve Guiratingia mendesi is redescribed from the original material. Detailed analysis of hinge and muscle scars allows more refined designation of its taxonomic position and affinities to other Permian bivalves from the Parana Basin. Guiratingia mendesi is characterized by very small, anteriorly expanded shells, with a great number of muscle striae within the area delimited by the pallial line. A flattened area is noted alongside the commissure of shell. The presence of a triangular blunt tooth in the right valve allows its designation to Megadesmidae. The absence of accessory muscle scars ""a"" and ""b"" and pedal elevator indicate that the genus belongs to the Plesiocyprinellinae, a group of bivalves considered endemic to the Passa Dois Group. Guiratingia mendesi is found, however, in limestones of the Palermo Formation (Middle Artinskian), nearly 100 in below the base of the Irati Formation (Late Artinskian). Until now, it was believed that within the Permian succession of Parana Basin, pre-Irati bivalves were all gondwanic or cosmopolitan. Guiratingia mendesi was an endemic, active burrower that resembles Runnegariella fragilis from the Permian Teresina Formation. This indicates that during Palermo times restricted paleogeographic conditions have existed within the huge Parana epeiric sea, favoring endemicity, probably in marine bayments close to its margins. The presence of an anteriorly expanded shell in G mendesi is a condition also seen in other Mesozoic and Cenozoic anomalodesmatans, demonstrating the recurrence of shell forms in distinct lineages of this interesting group of bivalves.

Study of partially encased composite beams with innovative position of stud bolts

In this article, static behavior of three partially encased composite beams under flexural condition is investigated in the context of studying some alternative positions for the headed studs. Shear resistance between the I-shaped beam and the concrete was provided by headed studs in two positions: vertically welded oil the bottom flange and horizontally welded on the faces of the web. Experimental results show that the headed studs provide the composite action and increase the bending strength. The most remarkable position seems to be the headed studs vertically welded oil the bottom flange. Ail analytical method to estimate the bending capacity of the encased beams is also proposed, giving a good prediction of the experimental results (C) 2008 Elsevier Ltd. All rights reserved.

Influence of the slice position on chloride migration tests for concrete in marine conditions

Chloride migration tests are used to measure the concrete capacity to inhibit chloride attack. Many researchers carry out this test in a slice of concrete extracted from the central part of cylindrical specimens, discarding about 75% of the concrete used to mold the specimens. This fact generated the question: would it be possible to extract more slices from a same specimen without losing the confidence in the results? The main purpose of this work is to answer this question. Moreover, another aim of this study was to show the difference of chloride penetration between finished faces and the formwork surfaces of concrete beams and slabs. The results indicated that it is possible to use more slices of a single specimen for a chloride migration test. Moreover, it was demonstrated that there is a significant difference of chloride penetration between the finished surface and the formwork surface of the specimens. (C) 2008 Elsevier Ltd. All rights reserved.

Functionality of the approach of hierarchical analysis in the full cost accounting in the IRP of a metropolitan airport

This work shows the application of the analytic hierarchy process (AHP) in the full cost accounting (FCA) within the integrated resource planning (IRP) process. For this purpose, a pioneer case was developed and different energy solutions of supply and demand for a metropolitan airport (Congonhas) were considered [Moreira, E.M., 2005. Modelamento energetico para o desenvolvimento limpo de aeroporto metropolitano baseado na filosofia do PIR-O caso da metropole de Sao Paulo. Dissertacao de mestrado, GEPEA/USP]. These solutions were compared and analyzed utilizing the software solution ""Decision Lens"" that implements the AHP. The final part of this work has a classification of resources that can be considered to be the initial target as energy resources, thus facilitating the restraints of the IRP of the airport and setting parameters aiming at sustainable development. (C) 2007 Elsevier Ltd. All rights reserved.