A system to evaluate the accuracy of a visual mosaicking methodology

When underwater vehicles navigate close to the ocean floor, computer vision techniques can be applied to obtain motion estimates. A complete system to create visual mosaics of the seabed is described in this paper. Unfortunately, the accuracy of the constructed mosaic is difficult to evaluate. The use of a laboratory setup to obtain an accurate error measurement is proposed. The system consists on a robot arm carrying a downward looking camera. A pattern formed by a white background and a matrix of black dots uniformly distributed along the surveyed scene is used to find the exact image registration parameters. When the robot executes a trajectory (simulating the motion of a submersible), an image sequence is acquired by the camera. The estimated motion computed from the encoders of the robot is refined by detecting, to subpixel accuracy, the black dots of the image sequence, and computing the 2D projective transform which relates two consecutive images. The pattern is then substituted by a poster of the sea floor and the trajectory is executed again, acquiring the image sequence used to test the accuracy of the mosaicking system

A Camera-Projector System for Robot Positioning by Visual Servoing

Positioning a robot with respect to objects by using data provided by a camera is a well known technique called visual servoing. In order to perform a task, the object must exhibit visual features which can be extracted from different points of view. Then, visual servoing is object-dependent as it depends on the object appearance. Therefore, performing the positioning task is not possible in presence of nontextured objets or objets for which extracting visual features is too complex or too costly. This paper proposes a solution to tackle this limitation inherent to the current visual servoing techniques. Our proposal is based on the coded structured light approach as a reliable and fast way to solve the correspondence problem. In this case, a coded light pattern is projected providing robust visual features independently of the object appearance

Mouse mammary tumor virus : a model system for regulation of gene expression

Mouse mammary tumor virus (MMTV) kommt prizipiell in zwei Formen vor. Erstens als integierte virale DNA (endogen vererbt), die in allen Zellen der Maus enthalten ist und zweitens als infektiöse Form, bei der sich die DNA nur im Kern von Brustdrüsenzellen integriert. Die erste Form verhält sich wie ein stummes Gen während die zweite Form aktiv ist, durch Glukocorticoide stimuliert wird und zum Mamma-Karzinom führt. Wir haben beide Typen von viralen Genen molekular geklont und durch Transfektion in verschiedene Zellen in Gewebekultur eingeführt. Wir konnten zeigen, dass sowohl die endogene DNA, wie dir infektiöse DNA in transfektieren Zellen aktiv ist und dass die Expression beider Gene durch Glukocorticoide stimuliert wird. Wir konnten die DNA Squenzen, die für dir Homonstimulierung nötig sind, in einem kleinen Fragment der viralen DNA lokalisieren. Bei der Sequenzanalyse dieses DNA-Stückes haben wir ein neues virales Gen entdeckt, das dir Information für ein Protein von ca. 40000 Moleklargewicht enthählt. Mit Hilfe eines Antikörpers suchen wir in verschiedenen Brustdrüsenzellen und Tumoren nach diesem Proetin, dessen Funktion noch nicht bekannt ist.

The efficiency of a novel delivery system (PEI600-Tat) in development of potent DNA vaccine using HPV16 E7 as a model antigen.

DNA vaccination is a promising approach for inducing both humoral and cellular immune responses. The mode of plasmid DNA delivery is critical to make progress in DNA vaccination. Using human papillomavirus type 16 E7 as a model antigen, this study evaluated the effect of peptide-polymer hybrid including PEI600-Tat conjugate as a novel gene delivery system on the potency of antigen-specific immunity in mice model. At ratio of 10:50 PEI-Tat/E7DNA (w/w), both humoral and cellular immune responses were significantly enhanced as compared with E7DNA construct and induced Th1 response. Therefore, this new delivery system could have promising applications in gene therapy.

Sample size and statistical power in the hierarchical analysis of variance: applications in morphometry of the nervous system.

Analysis of variance is commonly used in morphometry in order to ascertain differences in parameters between several populations. Failure to detect significant differences between populations (type II error) may be due to suboptimal sampling and lead to erroneous conclusions; the concept of statistical power allows one to avoid such failures by means of an adequate sampling. Several examples are given in the morphometry of the nervous system, showing the use of the power of a hierarchical analysis of variance test for the choice of appropriate sample and subsample sizes. In the first case chosen, neuronal densities in the human visual cortex, we find the number of observations to be of little effect. For dendritic spine densities in the visual cortex of mice and humans, the effect is somewhat larger. A substantial effect is shown in our last example, dendritic segmental lengths in monkey lateral geniculate nucleus. It is in the nature of the hierarchical model that sample size is always more important than subsample size. The relative weight to be attributed to subsample size thus depends on the relative magnitude of the between observations variance compared to the between individuals variance.

Prediction of 18-month survival in patients with primary myelodysplastic syndrome. A regression model and scoring system based on the combination of chromosome findings and the Bournemouth score.

The predictive potential of six selected factors was assessed in 72 patients with primary myelodysplastic syndrome using univariate and multivariate logistic regression analysis of survival at 18 months. Factors were age (above median of 69 years), dysplastic features in the three myeloid bone marrow cell lineages, presence of chromosome defects, all metaphases abnormal, double or complex chromosome defects (C23), and a Bournemouth score of 2, 3, or 4 (B234). In the multivariate approach, B234 and C23 proved to be significantly associated with a reduction in the survival probability. The similarity of the regression coefficients associated with these two factors means that they have about the same weight. Consequently, the model was simplified by counting the number of factors (0, 1, or 2) present in each patient, thus generating a scoring system called the Lausanne-Bournemouth score (LB score). The LB score combines the well-recognized and easy-to-use Bournemouth score (B score) with the chromosome defect complexity, C23 constituting an additional indicator of patient outcome. The predicted risk of death within 18 months calculated from the model is as follows: 7.1% (confidence interval: 1.7-24.8) for patients with an LB score of 0, 60.1% (44.7-73.8) for an LB score of 1, and 96.8% (84.5-99.4) for an LB score of 2. The scoring system presented here has several interesting features. The LB score may improve the predictive value of the B score, as it is able to recognize two prognostic groups in the intermediate risk category of patients with B scores of 2 or 3. It has also the ability to identify two distinct prognostic subclasses among RAEB and possibly CMML patients. In addition to its above-described usefulness in the prognostic evaluation, the LB score may bring new insights into the understanding of evolution patterns in MDS. We used the combination of the B score and chromosome complexity to define four classes which may be considered four possible states of myelodysplasia and which describe two distinct evolutional pathways.

The wound watch: an objective staging system for wounds in the diabetic (db/db) mouse model.

As in cancer biology, in wound healing there is a need for objective staging systems to decide for the best treatment and predictors of outcome. We developed in the diabetic (db/db) wound healing model, a staging system, the "wound watch," based on the quantification of angiogenesis and cell proliferation in open wounds. In chronic wounds, there is often a lack of cellular proliferation and angiogenesis that leads to impaired healing. The wound watch addresses this by quantifying the proliferative phase of wound healing in two dimensions (cellular division and angiogenesis). The results are plotted in a two-dimensional graph to monitor the course of healing and compare the response to different treatments.

Current status of a model system: the gene Gp-9 and its association with social organization in fire ants.

The Gp-9 gene in fire ants represents an important model system for studying the evolution of social organization in insects as well as a rich source of information relevant to other major evolutionary topics. An important feature of this system is that polymorphism in social organization is completely associated with allelic variation at Gp-9, such that single-queen colonies (monogyne form) include only inhabitants bearing B-like alleles while multiple-queen colonies (polygyne form) additionally include inhabitants bearing b-like alleles. A recent study of this system by Leal and Ishida (2008) made two major claims, the validity and significance of which we examine here. After reviewing existing literature, analyzing the methods and results of Leal and Ishida (2008), and generating new data from one of their study sites, we conclude that their claim that polygyny can occur in Solenopsis invicta in the U.S.A. in the absence of expression of the b-like allele Gp-9(b) is unfounded. Moreover, we argue that available information on insect OBPs (the family of proteins to which GP-9 belongs), on the evolutionary/population genetics of Gp-9, and on pheromonal/behavioral control of fire ant colony queen number fails to support their view that GP-9 plays no role in the chemosensory-mediated communication that underpins regulation of social organization. Our analyses lead us to conclude that there are no new reasons to question the existing consensus view of the Gp-9 system outlined in Gotzek and Ross (2007).

Hepatitis B and C virus coinfection: a novel model system reveals the absence of direct viral interference.

Coinfection with hepatitis B virus (HBV) and hepatitis C virus (HCV) has been associated with severe liver disease and frequent progression to cirrhosis and hepatocellular carcinoma. Clinical evidence suggests reciprocal replicative suppression of the two viruses, or viral interference. However, interactions between HBV and HCV have been difficult to study due to the lack of appropriate model systems. We have established a novel model system to investigate interactions between HBV and HCV. Stable Huh-7 cell lines inducibly replicating HBV were transfected with selectable HCV replicons or infected with cell culture-derived HCV. In this system, both viruses were found to replicate in the same cell without overt interference. Specific inhibition of one virus did not affect the replication and gene expression of the other. Furthermore, cells harboring replicating HBV could be infected with cell culture-derived HCV, arguing against superinfection exclusion. Finally, cells harboring replicating HBV supported efficient production of infectious HCV. Conclusion: HBV and HCV can replicate in the same cell without evidence for direct interference in vitro. Therefore, the viral interference observed in coinfected patients is probably due to indirect mechanisms mediated by innate and/or adaptive host immune responses. These findings provide new insights into the pathogenesis of HBV-HCV coinfection and may contribute to its clinical management in the future.