Lyme disease is a multisystemic disease which may result in arthritis, carditis, and neurological dysfunction. It is caused by the bacterium Borrelia burgdorferi which is transmitted by tick bite. A vaccine to protect humans from Borrelia burgdorferi infection is currently unavailable. However, recent studies suggest that protection against Lyme disease is antibody mediated and directed against surface exposed antigens. In this study, we have characterized a 66 kDa antigen from Borrelia burgdorferi. This antigen was found to be surface exposed by biochemical and immunochemical analysis. The characterization of the 66 kDa antigen was facilitated by the development of monoclonal and polyclonal antibodies. It is hoped that antibodies directed against the 66 kDa antigen will provide protective immunity and lead to the development of a broadly protective vaccine for the prevention of Lyme disease.
The project involves the interaction of computer software and a bobsled simulator cockpit. Engineers have developed a mathematical model and computer simulation of three-dimensional bobsled turning. A bobsled simulator cockpit is electronically connected to the computer. Thus, the computer graphics and feedback measurements are direct results of the manual steering inside the cockpit. Olympic bobsledders may use the bobsled simulator as a means to develop and improve their bobsledding skills. Bobsledders have limited time to practice which is partly due to the lack of accessibility to bobsled tracks.
The bobsled simulator cockpit gives the bobsledder the opportunity to practice at will. However, because of the weight, size, and bulkiness of the present bobsled cockpit, it has limited portability. Thus, I was asked to use my engineering expertise to design and build a portable bobsled cockpit that is not only easily accessed but which also possesses computer interface capabilities.
A current method frequently prescribed for the rehabilitation of knee and ankle injuries involves the use of a sled type leg press on which a patient lies horizontally and simulates jumping. The device is strictly mechanical and provides no indication of how well the patient is meeting the goals of the prescribed therapy.
This project focuses on the redesign of the current device by incorporation of a biomechanics force platform to the jumping surface. The force platform will measure forces and movements about three mutually perpendicular axes and these data can be instantaneously conveyed to the patient and/or the therapist. Data acquisition software has been developed so that a computer can process the information and display it in a digital and/or graphic form. Special integration schemes are utilized in the processing of the force data so that meaningful information is provided.
We describe the oceanic and atmospheric climatologies in the Tropical Pacific Ocean. These climatologies are contrasted with those simulated using the latest version of the UCLA coupled ocean-atmosphere global climate model. The model consists of an atmospheric component and an oceanic component. These components are copuled syschronously exchanging information on wind stress, precipitation, evaporation, heat fluxes, and sea surface temperature at the atmosphere-ocean interface.
The model results correspond to 10 years of simulation. We focus on vertical cross-sections of ocean temperature and west-east (zonal) velocity and horizontal maps of the wind stress vector. Model data display a wind stress pattern similar to the observed. The model successfully simulates the temperature distribution and the complex current structures that characterize this region. The current model does not produce El Nino events as strong as the observed, however. The reasons for this model behavior will be discussed.
Normal locomotion arises from neural signals activating muscles. The muscles move limbs and the result of limb movement is fed back to neural sensors. We simulated this process, following the model developed by Taga, G. et al. (Biol. Cybern. 65, pp. 147-159 (1991)). Six oscillators represent the neural controls on hip, knee, and ankle flexors and extensors. Their output is converted into torques that act through Newtonian mechanics on the relevant limb segments. Additional equations represent the pendular dynamics of the limbs, and resulting limb positions and torques become incorporated into the neural modules. Using graphic output consisting of stick figures, this model produces a realistic simulation of the human locomotor pattern in a variety of conditions. We have simulated the response to several additional conditions, including reduced gravity, and several pathologies such as neural disorders effecting coordination and muscle disorders resulting in muscle weakness.
The objective is to reversibly compress digital images by predictive coding. The previously encoded value is used as a prediction for the value at the next pixel location, and the difference is losslessly encoded. The set of difference values from -128 to +127 is converted by a binary decison tree such that each possible error value is represented by a leaf of that tree. An error value is encoded by coding which of the two possible branches is taken from each interior node of the binary tree, starting at the root node, and progressing to the node from which the appropriate leaf is subtended. The decoder, knowing the binary decision-tree branches from the root node that lead to the leaf representing the correct error value, follows the path to obtain the correct error value. The project compares the compression obtained from several alternative ways of designing the binary decision tree whose leaves are the prediction error values.
Key words: Image compression, predictive coding, arithmetic coding.
New spectroscopic methods have been used to determine the concentration of atomic and molecular states in photochemical systems and electrical discharges. Transient grating spectroscopy shows great promise as a non-invasive method or probing intermediates. We have performed transient grating experiments where all four of the laser frequencies are the same: degenerate four wave mixing (DFWM). We have applied this method to determine excited neon atom states in an electrical discharge, and to determine NH concentration in various ro-vibronic states. The efficiency of DFWM is compared with the better known laser-induced fluorescence technique. The primary advantage of DFWM is that there is no background signal when there is no absorbing species present. The primary disadvantage is that the signal is not linear in concentration, but depends on its square. The transient grating techniques have considerable potential uses in remote sensing.
There has been interest in the reactivity of metal complexes that specifically highlights the interactions of metal ions bonded to ligands that provide chalcogen anions as the donor centers. Recently, discrete homoleptic nickel (II) thiolates and selenolates have been reported by this group.
At this time, research efforts have been directed towards characterizations of complexes which contain both selenolates and thiolates coordinated to nickel. This arrangement is of biochemical significance with regard to hydrogenases, especially the [FeNiSe] hydrogenases from Desulfovibrio baculatu* and Desulfovibrio salexigens. In these hydrogenases, the nickel site is coordinated to cysteinate as well as selenocysteinate residues. We adopted the ligand exchange reaction as the first synthetic procedure. The redox properties of the selenolato-thiolato complexes of nickel will provide insight into the differences in behaviors of the [FeNi] and [FeNiSe] hydrogenases.
Under the instruction and guidance of Professor Gregory L. Long, I have made efforts to research and design a device capable of coordinating the manipulation of virtual objects in a realistic way through the development of a man-machine interface to acheive teleoperation in virtual environments. The manipulative procedures and exploratory processes will consist of touching, grasping, moving, and even assembling virtual objects while taking into account the object's geometrical dimensions and tactile qualities. The realistic control of these virtual objects will require that the proposed device initiate a force-feedback replication system capable of emmulating the virtual forces implemented upon the user's hand movements to replicate ideal contact conditions occuring between the virtual object and the virtual hand. High magnitude external forces such as gravity, object weight, and surface collisions as well as low magnitude external forces such as haptic conditions and surface temperature will also be addressed.
The use of plant derived products (i.e. leaves, roots, resins, etc.) by animals for possible self-medication purposes is our research interest. In the present study, the chemistry of the resin exuded by the tropical tree Trattinnickia aspera (Burseraceae) is being investigated. White-nosed coatia (Nasua narica) exhibit peculiar group behavior towards this exuded resin by rubbing it on their furs. We have proposed that this resin might possess insect repellency properties against ectoparasites (i.e. ticks, fleas, mites, flies, etc.). The use of modern isolation, purification, and structural elucidation techniques have resulted in the identification of four major constituents of this resin: two major triterpenes, a-amyrin 1 and b-amyrin 2, and two major sesquiterpenes, b-selinenes 3 and 8b-hydroxyasterolide 4. The procedure to isolate will be presented and the spectroscopic data for structural elucidation will be discussed.