An edge-detection approach to investigating pigeon navigation

This study brings together work in pattern recognition and animal behaviour. By applying algorithms in pattern recognition, we examined how visual landscape information influences pigeons' homing behaviour. We used an automated procedure (Canny edge detector) to extract edges from an aerial image of the experimental terrain. Analysis of pigeons' homing routes recorded using global positioning system (GPS) trackers showed that the chosen homing paths, as well as changes in the birds' navigational states, tended to coincide with these edges. This study demonstrates that some edge-containing land features attract homing pigeons and trigger changes in their navigational states.     

A memory-based self-generated basis function neural network.

The paper presents a novel memory-based Self-Generated Basis Function Neural Network (SGBFN) that is composed of small CMACs. The SGBFN requires much smaller memory space than the conventional CMAC and has an excellent learning convergence property compared to multilayer neural networks. Each CMAC in the new structure takes a subset of problem inputs as its inputs. Several CMACs that have different subsets of inputs form a submodule and a group of submodules form a neural network. The output of a submodule is the product of its CMACs' outputs. Each submodule implements a self-generated basis function, which is developed during the learning. The output of the neural network is the sum of the outputs from the submodules. Using only a subset of inputs in each CMAC significantly reduces the required memory space in high-dimensional modeling. With the same size of memory, the new structure is able to achieve a much smaller learning error compared to the conventional CMAC.     

View-based navigation in Hymenoptera: multiple strategies of landmark guidance in the approach to a feeder

In order to analyse how landmarks guide the last stages of an insect's approach to a goal, we recorded many flights of individual wasps and honeybees as they flew to an inconspicuous feeder on the ground that was marked by one or by two nearby landmarks. An individual tends to approach the feeder from a constant direction, flying close to the ground. Its body is oriented in roughly the same horizontal direction during the approach so that the feeder and landmarks are viewed over a narrow range of directions. Consequently, when the insect arrives at the feeder, the landmarks take up a standard position on the retina. Three navigational strategies govern the final approach. The insect first aims at a landmark, treating it as a beacon. Secondly, bees learn the appearance of a landmark with frontal retina and they associate with this stored view a motor trajectory which brings them from the landmark sufficiently close to the goal that it can be reached by image matching. Insects then move so as to put the landmark in its standard retinal position. Image matching is shown to be accomplished by a control system which has as set points the standard retinal position of the landmark and some parameter related to its retinal size. Accepted: 1 March 1997     

A cell surface clicked navigation system to direct specific bone targeting

Cell therapies are promising up-and-coming therapeutic strategies for many diseases. For maximal therapeutic benefits, injected cells have to navigate their way to a designated area, including organ and tissue; unfortunately, the majority of therapeutic cells are currently administered without a guide or homing device. To improve this serious shortcoming, a functionalization method was developed to equip cells with a homing signal. Its application was demonstrated by applying an Azadibenzocyclooctyne-bisphosphonate (ADIBO-BP) and azide paired bioorthogonal chemistry on cells for bone specific homing. Jurkat T cells and bone marrow derived stromal cells (BMSCs) were cultured with tetraacetylated N-azidoacetyl-d-mannosamine (Ac₄ManNAz) to place unnatural azido groups onto the cell’s surface; these azido groups were then reacted with ADIBO-BP. The tethered bisphosphonates were able to bring Jurkat cells to hydroxyapatite, the major component of bone, and mineralized SAOS-2 cells. The incorporated BP groups also enhanced the specific affinity of BMSCs to mouse femur bone fragments in vitro. The introduced navigation strategy is expected to have a broad application in cell therapy, because through the biocompatible ADIBO and azide reactive pair, various homing signals could be efficiently anchored onto therapeutic cells.     

A set-theoretical approach to biology

In a preceding paper (Bull. Math. Biophysics 20, 71–93, 1958) the principle of biotopological mapping was formulated in terms of a continuous mapping of an abstract space, made from the set of biological properties which characterize the organism, by an appropriate definition of neighborhoods. In this paper it is shown that we may consider directly the mappings of the different sets of properties which characterize different organisms without taking recourse to abstract spaces. All the verificable conclusions made in the preceding paper remain valid. A serious difficulty mentioned previously is, however, avoided and the possibility of more general predictions is established.     

A sociological approach to biology

The paper develops further some suggestions made previously (Bulletin of Mathematical Biophysics,28, 283–308, 1966) that certain biological phenomena may be more easily interpreted from a “sociological” point of view by considering the organism as a social aggregate of cells and a cell as a social aggregate of genes. In this light the problems of origin of life on earth, of aging, and of parasitism and symbiosis are discussed. The notion of social aggregates of different orders is introduced.     

A marketing approach to agar

Agar has, with the exception of certain retail markets in the Far East, specifically Japan, traditionally been sold to the industrial user. Small quantities are consumed in Islamic countries during Ramadan and in the Germanic countries as a food thickener and a laxative. However, outside of Japan, no significant marketing effort has ever been undertaken with a view to increase the demand for agar by consumers.A marketing plan is suggested to change this situation. All possible uses for agar by the consumer have been identified and studied. The special features of the product, together with certain packaging, are highlighted. Potential markets for these features are identified. Strategies for the development of these markets have been developed. The overall plan is now in a state of final review and just prior to implementation. The product launch should generate a significant consumer awareness which will translate into demand, thereby increasing the market for agar in various forms, formulations and packagings.     

A synthetic approach to ceramidephosphorylethanolamines

A general method to synthesize ceramidephosphorylethanolamines via 3-benzoylceramidephosphates using N-tritylaziridine is proposed.     

A macroscopic approach to demography

A canonical/lognormal model for human demography is established, specifying the net maternity function and the age distribution for mothers of new-borns using a single macroscopic parameter vector of dimension five. The age distribution of mothers is canonical, while the net maternity function normalizes to a lognormal density. Comparison of an actual population with the model serves to identify anomalies in the population which may be indicative of phase transitions or influences from levels outside the demographic. Tracking the time development of the parameter vector may be used to predict the future state of a population, or to interpolate for data missing from the record. In accordance with classical theoretical considerations of Backman, Prigogine, et al., it emerges that the logarithm of a mothers age is the most fundamental time variable for demographic purposes.     

A new approach to microhomogenization

A versatile microhomogenizer is described which is capable of handling sample volumes ranging from 1 μl to several millititers. The sample and homogenization buffer are sealed within a segment of flexible plastic tubing. The sample is disrupted by rubbing or rolling a metal rod back and forth over the length of tubing. Centrifugation of the homogenate is performed in the same sealed tubing segment. This method can be used to homogenize single cells.     

A recurrent network for landmark-based navigation

A new type of network is proposed that can be applied to landmark navigation. It solves the guidance task, that is, it finds a nonvisually marked location using knowledge concerning its spatial relation to other, visible landmarks. The path to the searched location is not disturbed if a landmark is not visible for some time. The network can also describe findings obtained by experiments with insects and rodents, where the position of the landmarks has been changed after training. In this net, recognition does not occur by searching for a match between a pattern seen and the same pattern being stored but by searching for a match between a pattern seen with a prediction calculated from different data. A simple extension allows a unique match of the landmarks seen with the items stored in memory. With this extension a recognition of the individual landmark is not necessary. A specific output unit of the network can be interpreted in such a way as to show properties of place cells found in vertebrates and the function of the network proposed here as to determine the input to a place cell. The model can explain the observation that a given place cell can also be active when the animal moves in a different environment. An extension is discussed of how the network could be exploited for recognition-triggered response that allows animals to follow fixed routes.