The combined results demonstrate an extremely important role for visual landmarks in familiar area navigation, and provide evidence as to how familiar visual landmarks are remembered, recognised, and encoded by homing pigeons.

Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.

No description available.

This study investigated transferrin inheritance in homing pigeons (Columba livia), using discontinuous acrylamide gel electrophoresis on rivanol treated serum.

Context: Standard transport layer protocols like UDP, TCP, andSCTP use only one access technology at a time. Concurrent MultipathTransmission (CMT), has been developed for parallel use of the access technologies. The main theme of this thesis work is to implement CMT in real-time and evaluate the impact of various scheduling algorithms on its performance. Objectives: The main objectives of this thesis are to implement a de-multiplexer at the source, re-sequencer at the receiver and to investigate some of the heuristics and analyzing their impact based on some performance metrics. Methods: Thorough understanding on this topic is attained by literature review of related works. To implement and evaluate the different scheduling patterns an experimental test bed is set up. For thetransmission of data, socket programming in Python is used. Varying various parameters that are involved in the experiment, performance metrics were measured and based on them statistical analysis is carried out for proper evaluation. Results: CMT is implemented in real-time test bed and concurrency is validated. Weighted Round-Robin has better performance compared to that of Round-Robin when the size of the packet is large whereas both exhibit nearly same behavior for smaller packet sizes. Conclusions: It can be concluded that Weighted Round-Robin attains higher throughput. It can be possibly due to more load of fragmentation when large packets are transmitted on the high reliable path and hence better performance than Round-Robin. There is need for further evaluation of other metrics like delay, jitter and using other scheduling mechanisms and in other environments as well.

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California / UUV homing and docking and UAV collision avoidance are two seemingly separate research topics for different applications. Upon close examination, these two are a pair of dual problems, with interesting correspondences and commonality. In this paper, we present the theoretical analysis, signal processing, and the field experiments of these two algorithms in UAV and UUV applications in homing and docking as well as collision avoidance.

No description available.

En thérapie génique ex vivo, les vecteurs lentiviraux peuvent être utilisés pour transduire les progéniteurs hématopoïétiques. Mais l’utilisation de vecteurs intégratifs non site-spécifique peut conduire à une mutagénèse insertionnelle. J’ai évalué le niveau de transduction des progéniteurs hématopoïétiques en mesurant le nombre de copies de vecteur intégrées dans des colonies cellulaires isolées. Il a été montré que la fréquence des cellules transduites et la distribution du nombre de copies de vecteur intégrées peut dépendre des conditions expérimentales. L’utilisation de vecteurs ciblant l’insertion du transgène à un site précis du génome permettrait de surmonter les problèmes de génotoxicité. Les introns de groupe II sont des éléments génétiques auto-épissable mobiles pouvant d’intégrer à un site précis du génome. Ils sont utilisés en ciblage génomique chez les procaryotes, mais pas chez les eucaryotes, probablement dû à une activité catalytique limitée dans ces cellules. J’ai étudié l’intron de groupe II Pl.LSU/2 de Pylaiella littoralis, qui est le seul capable de s’auto-épisser à des concentrations très faibles de magnésium. La protéine codée par l’intron Pl.LSU/2 (IEP) exprimée chez Escherichia coli a été purifiée et a montré une activité de transcriptase inverse soit seule, soit associée à l’intron ARN. Il a été montré que l’intron Pl.LSU/2 peut s’épisser chez Saccharomyces cerevisiae et que l’efficacité de l’épissage est augmentée par l’activité maturase de l’IEP. Cependant, les transcrits épissés ne sont pas traduits, et l’épissage de l’intron n’a pas été démontré dans les cellules humaines, tout comme le homing de l’intron chez E. coli et S. cerevisiae. / In ex vivo hematopoietic gene therapy, lentiviral vectors can be used to transduce hematopoietic progenitors. However, the use of non site-specific integrating vectors may lead to insertional mutagenesis. I evaluated the level of transduction of hematopoietic progenitor cells at the single-cell level by measuring vector copy number in individual colony-forming cell units. It was shown that the frequency of transduced progenitor cells and the distribution of VCN in hematopoietic colonies may depend upon experimental conditions. Nevertheless, the use of vectors that can target the integration of the transgene into a specific-site of the host genome would overcome genotoxicity issues. I evaluated the use of a group II intron for genomic targeting. Group II introns are self-splicing mobile elements that can integrate into precise genomic locations by homing. Engineered group II introns are commonly used for targeted genomic modifications in prokaryotes but not in eukaryotes, probably due limited catalytic activation in these cells. I studied the brown algae Pylaiella littoralis Pl.LSU/2 group II intron which is uniquely capable of in vitro ribozyme activity at unusually low level of magnesium. Recombinant Pl.LSU/2 IEP expressed in Escherichia coli was purified and showed a reverse transcriptase activity either alone or associated with intronic RNA. The Pl.LSU/2 intron was showed to splice accurately in Saccharomyces cerevisiae and splicing efficiency was improved by the maturase activity of the intron-encoded protein. However, spliced transcripts were not expressed, and intron splicing was not detected in human cells, as well as homing of Pl.LSU/2 in E. coli and S. cerevisiae.

Giving robots the ability to move around autonomously in various real-world environments has long been a major challenge for Artificial Intelligence. New approaches to the design and control of autonomous robots have shown the value of drawing inspiration from the natural world. Animals navigate, perceive and interact with various uncontrolled environments with seemingly little effort. Flying insects, in particular, are quite adept at manoeuvring in complex, unpredictable and possibly hostile environments.Inspired by the miniature machine view of insects, this thesis contributes to the autonomous control of mobile robots through the application of insect-based visual cues and behaviours. The parsimonious, yet robust, solutions offered by insects are directly applicable to the computationally restrictive world of autonomous mobile robots. To this end, two main navigational domains are focussed on: corridor guidance and visual homing.Within a corridor environment, safe navigation is achieved through the application of simple and intuitive behaviours observed in insect, visual navigation. By observing and responding to observed apparent motions in a reactive, yet intelligent way, the robot is able to exhibit useful corridor guidance behaviours at modest expense. Through a combination of both simulation and real-world robot experiments, the feasibility of equipping a mobile robot with the ability to safely navigate in various environments, is demonstrated.It is further shown that the reactive nature of the robot can be augmented to incorporate a map building method that allows previously encountered corridors to be recognised, through the observation of landmarks en route. This allows for a more globally-directed navigational goal.Many animals, including insects such as bees and ants, successfully engage in visual homing. This is achieved through the association of ++ / visual landmarks with a specific location. In this way, the insect is able to 'home in' on a previously visited site by simply moving in such a way as to maximise the match between the currently observed environment and the memorised 'snapshot' of the panorama as seen from the goal. A mobile robot can exploit the very same strategy to simply and reliably return to a previously visited location.This thesis describes a system that allows a mobile robot to home successfully. Specifically, a simple, yet robust, homing scheme that relies only upon the observation of the bearings of visible landmarks, is proposed. It is also shown that this strategy can easily be extended to incorporate other visual cues which may improve overall performance.The homing algorithm described, allows a mobile robot to home incrementally by moving in such a way as to gradually reduce the discrepancy between the current view and the view obtained from the home position. Both simulation and mobile robot experiments are again used to demonstrate the feasibility of the approach.

Phage display is a molecular technique accomplished by incorporation of the nucleotide sequence encoding the protein to be displayed into a phage or phagemid genome as a fusion to a gene encoding a phage coat protein. After several rounds of selection and amplification, high affinity phage clones, and thus high affinity ¡§homing peptides¡¨ can be obtained. Cell-binding homing peptides selected in this manner could be linked by physical or genetic manipulation to gene therapy vectors that mediate their own entry (viral or non-viral vectors) to facilitate targeting. Homing peptides that target specific cellular receptors can also be used as a treatment modality to induce various signal transduction pathways or even apoptotic signals of cancer cells. Oral squamous cell carcinoma (OSCC) is one of the most common cancers in the world. It has become the fourth cancer death reason of males in Taiwan. Radical surgery combined with postoperative chemotherapy and/or radiotherapy is still the major modality for treatment of OSCC. The 5-year survival rate of OSCC is still discouraged in recent years. Patients with OSCC present numerous challenges to treating physicians. In this study, we aimed to isolate and identify homing phage clones specific to oral cancer cells by panning with a random phage peptide library. The homing phage clones will be used as a basis to improve targeting specificity of gene therapy vectors. A NCBI BLAST search was performed and close similarities were found to several important molecules biologically with the homing peptides carried by phage clones. Characterization of the selected phage-29 was then studied by immunohistochemical methods. Internalization of this phage-29 is sequence-specific and mediated by integrin £\v£]6 in HSC-3 cells rapidly. We also confirmed that the integrin £\v£]6-targeting homing peptide is universally useful in all major kinds of head and neck cancer. We will further study the possible biological functions of the other homing peptides to see whether these peptides could have potential applications for oral cancer treatment.