Positioning and localization of two-wavelength interferograms for wavefront reconstruction with volume holographic media

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

An objective reconstruction of the chain of contagion

North's clustering method, which is based on a much used ecological model, the nearest neighbor distance, was applied to the objective reconstruction of the chain of household-to-household transmission of variola minor (the mild form of smallpox). The discrete within-household outbreaks were considered as points which were ordered in a time sequence using a 10-40 day interval between introduction of the disease into a source household and a receptor household. The closer points in the plane were assumed to have a larger probability of being links of a chain of household-to-household spread of the disease. The five defining distances (Manhattan or city-block distance between presumptive source and receptor dwellings) were 100, 200, 300, 400 and 500 m. The subchain sets obtained with the five defining distances were compared with the subchains empirically reconstructed during the field study of the epidemic through direct investigation of personal contacts of the introductory cases with either introductory or subsequent cases from previously affected households. The criteria of fit of theoretical to empirical clusters were: (a) the number of clustered dwellings and subchains, (b) number of dwellings in a subchain and (c) position of dwellings in a subchain. The defining distance closet to the empirical findings was 200 m, which fully agrees with the travelling habits of the study population. Less close but acceptable approximations were obtained with 100, 300, 400 and 500 m. The latter two distances gave identical results, as if a clustering ceiling had been reached. It seems that North's clustering model may be used for an objective reconstruction of the chain of contagious whose links are discrete within-household outbreaks. © 1984.

Surface reconstruction using multiple light sources and perspective projection

This paper presents a method to recover 3D geometry of Lambertian surfaces by using multiple images taken from the same view point and with the scene illuminated from different positions. This approach differs from Stereo Photometry in that it considers the light source at a finite distance from the object and the perspective projection in image formation. The proposed model allows local solution and recovery of 3D coordinates, in addition to surface orientation. A procedure to calibrate the light sources is also presented. Results of the application of the algorithm to synthetic images are shown.

Three-dimensional reconstruction of fracture surfaces: Area matching algorithms for automatic parallax measurements

This paper describes two solutions for systematic measurement of surface elevation that can be used for both profile and surface reconstructions for quantitative fractography case studies. The first one is developed under Khoros graphical interface environment. It consists of an adaption of the almost classical area matching algorithm, that is based on cross-correlation operations, to the well-known method of parallax measurements from stereo pairs. A normalization function was created to avoid false cross-correlation peaks, driving to the true window best matching solution at each region analyzed on both stereo projections. Some limitations to the use of scanning electron microscopy and the types of surface patterns are also discussed. The second algorithm is based on a spatial correlation function. This solution is implemented under the NIH Image macro programming, combining a good representation for low contrast regions and many improvements on overall user interface and performance. Its advantages and limitations are also presented.

Qualitative analysis of two reconstruction techniques and their application in dentistry

Although visualization in the field of dentistry has some of the same requirements as the medicine field, the differences in goal demand specific approaches. This paper reports on the implementation of two fundamentally different approaches to reconstruction of structures from planar cross sections and their application to dentistry data. One of the approaches was an implementation of a distance-based sampling technique, and the other is a new algorithm, based on the Delaunay triangulation. Both were tested using contour data of teeth and the results are compared here in the light of the target applications, which are teaching and training dentistry, as well as simulation of dental procedures and illnesses. Widely mentioned problems encountered in local reconstruction methods such as marching cubes for these cases are clearly illustrated in this paper, and a very satisfactory alternative is given. © 2000 SPIE and IS&T.

Postural control in children: Coupling to dynamic somatosensory information

The purpose of this investigation was to determine whether the coupling between dynamic somatosensory information and body sway is similar in children and adults. Thirty children (4-, 6-, and 8-year-olds) and 10 adults stood upright, with feet parallel, and lightly contacting the fingertip to a rigid metal plate that moved rhythmically at 0.2, 0.5, and 0.8 Hz. Light touch to the moving contact surface induced postural sway in all participants. The somatosensory stimulus produced a broadband frequency response in children, while the adult response was primarily at the driving frequency. Gain, as a function of frequency, was qualitatively the same in children and adults. Phase decreased less in 4-year-olds than other age groups, suggesting a weaker coupling to position information in the sensory stimulus. Postural sway variability was larger in children than adults. These findings suggest that, even as young as age 6, children show well-developed coupling to the sensory stimulus. However, unlike adults, this coupling is not well focused at the frequency specified by the somatosensory signal. Children may be unable to uncouple from sensory information that is less relevant to the task, resulting in a broadband response in their frequency spectrum. Moreover, higher sway variability may not result from the sensory feedback process, but rather from the children's underdeveloped ability to estimate an internal model of body orientation.

Holocene paleoclimatic reconstruction based on the Lagoa Dourada deposits, southern Brazil

The Lagoa Dourada is a circular-shaped pond formed on the Furnas Formation (Devonian of the Paraná Basin), filled by late Pleistocene - Holocene sediments. It lies in the hydrographic basin of the Guabiroba River, a tributary of the Tibagi River situated in the Campos Gerais region of the State of Paraná, southern Brazil. The pond is about 200 m in diameter and the maximum water depth is 5.4 m. Geological, chemical, textural and mineralogical studies on a core sample of the sediments collected from the Lagoa Dourada, 12.2 m thick, was obtained for investigations of paleoenvironmental changes as well as to provide additional data to support previous reconstructions based on palynomorphs and diatoms. Within the period recorded in the core, the pond has been filled by sandy material introduced by springs at the northern edge of the pond as well as by muddy material brought in by floodwaters of the Guabiroba River. Thus, the sandy layers could be interpreted as evidence of drier climates with consequent diminution of fluvial overflow, but with maintenance of the sandy deposits coming from springs. The occurrence of euhedral pyrite in the sediments, locally associated with gypsum, may indicate periods of increase in the organic matter content or an increase in the water salinity, what could be related to greater evaporation under drier paleoclimate regimes. Three cycles defined by an increase in the total carbon content of the sediments of the pond were observed. These cycles seem to correspond to an increase in the isotope ratio 13C/12C (δ13C). Several hypotheses can be suggested to explain the presence of these cycles, including the alternation of wetter or drier climatic phases. The convergence of the sedimentological data obtained during this study with previous microfossil paleoclimatic (pollens and diatoms) indicators and radiocarbon dating suggests that a drier paleoclimatic phase occurred around 8720±150 years B.P. The evidence for a second drier phase in more recent times is less consistent. This subsequent phase could correspond to the drier phase in southern and southeastern Brazil between 5000 and 3000 years B.P. as suggested by other paleoclimatic studies.

Proposal of a new technique for bile duct reconstruction after iatrogenic injury. Study in dogs and review of the literature

Purpose: Interposition of a jejunal tube between the common bile duct and duodenum. Methods: Five adult mongrel dogs of both sexes, weighing on average 22.3 kg (18 to 26.5 kg), were used. Obstructive jaundice was induced by ligation of the distal common bile duct. After one week, a 2.5-cm long jejunal tube was fabricated from a segment of the loop removed 15 cm from the Treitz angle and interposed between the common bile duct and duodenum. Results: The animals presented good clinical evolution and no complications were observed. After 6 weeks, complete integration was noted between the bile duct mucosa, tube and duodenum and a significant reduction in total bilirubin and alkaline phosphatase was observed when compared to the values obtained one week after ligation of the common bile duct. Conclusion: The jejunal tube interposed between the dilated bile duct and duodenum showed good anatomic integration and reduced total bilirubin and alkaline phosphatase levels in the animals studied.

Reconstruction of Mandibular Segmental Defects Using the Guided-Bone Regeneration Technique With Polylactide Membranes and/or Autogenous Bone Graft: A Preliminary Study on the Influence of Membrane Permeability

Purpose: Bone maintenance after mandibular reconstruction with autogenous iliac crest may be disappointing due to extensive resorption in the long term. The potential of the guided-bone regeneration (GBR) technique to enhance the healing process in segmental defects lacks comprehensive scientific documentation. This study aimed to investigate the influence of polylactide membrane permeability on the fate of iliac bone graft (BG) used to treat mandibular segmental defects. Materials and Methods: Unilateral 10-mm-wide segmental defects were created through the mandibles of 34 mongrel dogs. All defects were mechanically stabilized, and the animals were divided into 6 treatment groups: control, BG alone, microporous membrane (poly L/DL-lactide 80/20%) (Mi); Mi plus BG; microporous laser-perforated (15 cm2 ratio) membrane (Mip), and Mip plus BG. Calcein fluorochrome was injected intravenously at 3 months, and animal euthanasia was carried out at 6 months postoperatively. Results: Histomorphometry showed that BG protected by Mip was consistently related to larger amounts of bone compared with other groups (P ≤ .0001). No difference was found between defects treated with Mip alone and BG alone. Mi alone rendered the least bone area and reduced the amount of grafted bone to control levels. Data from bone labeling indicated that the bone formation process was incipient in the BG group at 3 months postoperatively regardless of whether or not it was covered by membrane. In contrast, GBR with Mip tended to enhance bone formation activity at 3 months. Conclusions: The use of Mip alone could be a useful alternative to BG. The combination of Mip membrane and BG efficiently delivered increased bone amounts in segmental defects compared with other treatment modalities. © 2008 American Association of Oral and Maxillofacial Surgeons.

Time reconstruction and performance of the CMS electromagnetic calorimeter

The resolution and the linearity of time measurements made with the CMS electromagnetic calorimeter are studied with samples of data from test beam electrons, cosmic rays, and beam-produced muons. The resulting time resolution measured by lead tungstate crystals is better than 100 ps for energy deposits larger than 10 GeV. Crystal-to-crystal synchronization with a precision of 500 ps is performed using muons produced with the first LHC beams in 2008. © 2010 IOP Publishing Ltd and SISSA.

Performance of CMS muon reconstruction in cosmic-ray events

The performance of muon reconstruction in CMS is evaluated using a large data sample of cosmic-ray muons recorded in 2008. Efficiencies of various high-level trigger, identification, and reconstruction algorithms have been measured for a broad range of muon momenta, and were found to be in good agreement with expectations from Monte Carlo simulation. The relative momentum resolution for muons crossing the barrel part of the detector is better than 1% at 10 GeV/c and is about 8% at 500 GeV/c, the latter being only a factor of two worse than expected with ideal alignment conditions. Muon charge misassignment ranges from less than 0.01% at 10GeV/c to about 1% at 500 GeV/c. © 2010 IOP Publishing Ltd and SISSA.

A importância das informações aferentes podais para o controle postural

Introduction. The postural control involves a complex mechanism for connecting the afferent and efferent pathways and their integration into the central nervous system (CNS). Three systems are responsible to obtain outside information: visual, vestibular and sensory. Recent studies have shown that among such systems, the CNS shows a greater predilection for sensory information to postural control. Objective. Given this, the review proposes to discuss the feet sensory information importance and its reflection in postural control mechanisms. Method. For this reason, a literature search was carried out by PubMed and Bireme libraries, and papers of the last five years were selected. Specific books were also used. Discussion. Studies were separated into topics on sensory information integration to neuro-motor answer, postural feed-forward adjustments recruitment mechanisms; neuro-muscular coordination and synergy responses and the musculoskeletal tissues role. Conclusion. Despite has been found a large number of studies, the real mechanism that the CNS uses to filter, integrate and process the sensory information and select the appropriate motor response, be it for the movement or posture for the stabilization remains obscure.

Efeitos de tarefas cognitivas no controle postural de idosos: Uma revisão sistemática

Demanding attention in order to keep postural balance increases with aging and with the presence of concurrent tasks that require information processing. Several studies have demonstrated that motor performance can be related to the complexity of the task and aging process, presenting a possible interaction between these factors. The aim of this review was to identify and analyze published papers about the effects of cognitive tasks on the postural control of elderly individuals. A systematic search in the Web of Science, SportDiscus, CINAHL, Science Direct on line, Biological Abstracts, PsycINFO, and Medline databases was made and 444 articles were found. Eight were selected that studied the variables of interest. These studies showed that postural control seems to be influenced by the individual's attention processes and that deficits in such ability may be associated to an increased risk of falls. © FTCD/CIDESD.

O papel dos sistemas visual, vestibular, somatosensorial e auditivo para o controle postural

The maintenance of a given body orientation is obtained by the complex relation between sensory information and muscle activity. Therefore, this study purpose was to review the role of visual, somatosensory, vestibular and auditory information in the maintenance and control of the posture. Method. a search by papers for the last 24 years was done in the PubMed and CAPES databases. The following keywords were used: postural control, sensory information, vestibular system, visual system, somatosensory system, auditory system and haptic system. Results. the influence of each sensory system and its integration were analyzed for the maintenance and control of the posture. Conclusion. the literature showed that there is information redundancy provided by sensory channels. Thus, the central nervous system chooses the main source for the posture control.