A survey of sensory data boundary estimation,covering and tracking techniques using collaborating sensors

Boundary estimation and tracking have important applications in the areas of environmental monitoring and disaster management. A boundary separates two regions of interest in a phenomenon. It can be visualized as an edge if there is a sharp change in the field value between the two regions or alternatively, as a contour with a field value $f=\tau$ separating two regions with field values $f>\tau$ and $f<\tau$. Examples include contours/boundaries of hazardous concentration in a pollutant spill, frontal boundary of a forest fire, isotherms, isohalines etc. Recent advances in the area of embedded sensor devices and robotics have led to deployments of networks of sensors capable of sensing, computing, communication and mobility. They are used to estimate the boundaries of interest in physical phenomena, monitor or track them over time and also in some cases, mitigate the spatial spread of the phenomena. Since these sensors work autonomously in the environment, minimizing the energy consumed while maximizing the accuracy of estimation or tracking is the main challenge for algorithms for boundary estimation and tracking. Several algorithms with these objectives have been proposed in the literature. In this work, we focus on the algorithms that estimate and cover boundaries found in the sensory data in a field and not the topological boundary of the sensor network per se, which is beyond the scope of this paper.Here, our objective is to provide a comprehensive survey of the algorithms for boundary estimation and tracking by providing a taxonomy based on two broad categories — (i) Boundary estimation and tracking, where the sensors estimate the boundary without physically covering the boundary and (ii) Boundary covering — where the sensors not only predict the location and estimate the entire boundary but also physically cover the boundary by surrounding and bounding it. We further classify the techniques based on (a) sensing capabilities —in situ, range or remote sensing (b) movement capabilities — static or mobile sensors and (c) boundary type — static or dynamic and (d) type of estimation — field estimation where the entire field is sampled to search for contours and localized estimation where sampling is done near the boundary and (e) different types of mobility models in the case of mobile sensors. We believe that such a survey has not been performed before. By capturing and classifying the current state-of-the-art and identifying open research problems, we hope to ignite interest and stimulate efforts towards promising solutions for real-world boundary estimation and tracking problems.     

Purification, crystallisation and preliminary X-ray diffraction study of ribosome inactivating protein: saporin

OBJECTIVES: To compare transesophageal atrial pacing stress echocardiography with dobutamine stress echocardiography for feasibility, safety, duration, patient acceptance and concordance in inducing wall motion abnormalities. BACKGROUND: Transesophageal atrial pacing is an effective method of increasing heart rate and has been used in the assessment of coronary artery disease. METHODS: Both tests were performed in sequence on the same patients in random order. Transesophageal atrial pacing stress echocardiography began at a heart rate of 10 beats/min above the baseline value and was increased by 20 beats/min every two min until 85% of the age-predicted maximum heart rate or another end point was reached. Dobutamine echocardiography was performed using three-min stages and a maximum dose of 40 microg/kg per min. Atropine (total dose < or =2 mg) was administered at the start of the 40 microg/kg per min stage if needed to augment heart rate or during pacing if Wenckebach heart block occurred. RESULTS: Transesophageal atrial pacing stress echocardiography was feasible in 100 of 104 patients (96%); the duration (8.6+/-3.6 min) was significantly shorter than that of dobutamine stress echocardiography (15.1+/-3.9 min) (p = 0.0001). With transesophageal atrial pacing stress echocardiography, the recovery period was shorter, symptoms and dysrhythmias were fewer, hypertension and hypotension were less common and target heart rate was more frequently achieved. No complications occurred with either test. Patient acceptance was satisfactory. Agreement between results of both tests was good for segmental wall motion scoring with a 16-segment model, scores 1 to 5 (kappa: rest, 0.79; peak, 0.57) and test interpretation (normal, ischemia, infarction or resting wall motion abnormality with ischemia) (kappa: 0.77). CONCLUSIONS: Transesophageal atrial pacing stress echocardiography is a feasible, well-tolerated alternative to dobutamine stress echocardiography. It can be performed rapidly and shows good agreement with dobutamine stress echocardiography in the induction of myocardial ischemia.     

Titration curves of p-hydroxybenzoic acid/formaldehyde/p-bromophenol copolymers

Copolymers obtained by the condensation of p-hydroxybenzoic acid, p-bromophenol, and formaldehyde showed characteristic titration curves in non-aqueous media. The titration curves indicated a series of breaks which bear integral relations to each other. These features have been interpreted in terms of homoconjugation, intramolecular hydrogen bond formation, and composition of the copolymers.     

Synthesis and properties of acrylamide-substituted base pair specific dyes for deoxyribonucleic acid template mediated synthesis of dye polymers

We have tried to construct synthetic polymers for sequence-specific recognition and complexation of longer deoxynucleotide sequences. For this purpose, we developed a method of template-directed polymerization of basic pair specific DNA ligands such as basic dyes. The template-directed polymerization consists in a copolymerization of various dyes of different specificities staying simultaneously in a binding equilibrium with DNA. In the present paper, we describe the synthesis and the properties of base pair specific monomers especially designed for performance of radical chain polymerization reactions in aqueous medium at room temperature. Different acrylamide derivatives of well-known dyes, such as AT-specific malachite green and GC-specific phenyl neutral red, were synthesized and studied for their ability of base pair specific complex formation with DNA of different base composition. Partition equilibrium dialysis and dye titration agarose gel electrophoresis were used to ensure for several dyes that they may be incorporated into different polymers via copolymerization of their acrylamido derivatives with various small base-unspecific monomers without substantial change of their binding parameters. Furthermore, we demonstrate that acrylamide and other small acrylamide derivatives can be used as building blocks for the synthesis of polymeric links between base pair specific monomers. The results and their consequences for template polymerization reactions are discussed.     

Quantum diffusion of hydrogen

A brief overview is given on low temperature diffusive behaviour of H in Nb(OH) _x , and measurement of diffusion, primarily by neutron scattering. We go in some detail into recent work on calculations of neutron structure factor as well as the diffusion coefficient of hydrogen, influenced by two-level excitations. Both the electronic and phononic contributions are covered. The importance of similar two-level excitations in insulating and metallic glasses is also pointed out.     

The role of Asn14 in the stability and conformation of the reactive-site loop of winged bean chymotrypsin inhibitor: crystal structures of two point mutants Asn14{->}Lys and Asn14{->}Asp

A double-headed chymotrypsin inhibitor, WCI, from winged beanseeds was cloned for structural and biochemical studies. Theinhibitor was subjected to two point mutations at a conservedposition, Asn14. This residue, known to have a pivotal rolein stabilizing the first reactive-site loop (Gln63–Phe68)of the inhibitor, is highly conserved in the sequences of theother members of Kunitz (STI) family as well as in the sequencesof Kazal family of serine protease inhibitors. The mutants,N14K and N14D, were subjected to biochemical assay and theircharacteristics were compared with those of the recombinantinhibitor (rWCI). Crystallographic studies of the recombinantand the mutant proteins are discussed. These studies were primarilyaimed at understanding the importance of the protein scaffoldingtowards the conformational rigidity of the reactive-site loop.Our analysis reveals that, as the Lys14 side chain takes anunusual fold in N14K and the Asp14 side chain in N14D interactswith the loop residues by water-mediated hydrogen bonds, thecanonical conformation of the loop has remained effectivelyintact in both the mutant structures. However, minor alterationssuch as a 2-fold increase in the inhibitory affinity towardsthe cognate enzyme were observed.