Biosensor development has the potential to meet the need for rapid, sensitive, and specific detection of pathogenic bacteria from natural sources. An antibody-based fiber-optic biosensor assay to detect low levels of Vibrio vulnificus in estuarine waters following an enrichment step was developed. The principle of the sensor is based on an immuno-sandwich assay where an anti-V. vulnificus polyclonal capture antibody preparation was first immobilized on a polystyrene fiber-optic waveguide using a biotin-avidin association. The capture antibody is responsible for binding the target cells to the waveguide. Cyanine-5-conjugated anti-V. vulnificus polyclonal antibodies are subsequently allowed to bind to immobilized cells, and detection occurs when a photodetector collects emitted light (670-710 nm) from the fluorophore, which is excited with 635-nm laser light produced by the Analyte 2000 biosensor. Any detection signal greater than a pre-determined threshold signal is considered to be a positive detection event, while any signal lower than the threshold is considered no detection. This immunosensor assay proved highly specific when tested against whole cells and cell extracts from V. cholerae, V. parahaemolyticus, V. alginolyticus, and E. coli. isolates. Following a four hour enrichment in PNCC broth, and in a total of less than seven hours, the assay was able to detect cell extracts from as few as 100 V. vulnificus colony forming units suspended in sterile water. This method holds promise for detection of low numbers V. vulnificus and other autochthonous pathogens in estuarine waters.

<p>Future parallel computer systems for embedded real-time applications,where each node in itself can be a parallel computer, are predicted to havevery high bandwidth demands on the interconnection network. Otherimportant properties are time-deterministic latency and guarantees to meetdeadlines. In this thesis, a fiber-optic passive optical star network with amedium access protocol for packet switched communication in distributedreal-time systems is proposed. By using WDM (Wavelength DivisionMultiplexing), multiple channels, each with a capacity of several Gb/s, areobtained.</p><p>A number of protocols for WDM star networks have recently been proposed.However, the area of real-time protocols for these networks is quiteunexplored. The protocol proposed in this thesis is based on TDMA (TimeDivision Multiple Access) and uses a new distributed slot-allocationalgorithm with real-time properties. Services for both guarantee-seekingmessages and best-effort messages are supported for single destination,multicast, and broadcast transmission. Slot reserving can be used toincrease the time-deterministic bandwidth, while still having an efficientbandwidth utilization due to a simple slot release method.</p><p>By connecting several clusters of the proposed WDM star network by abackbone star, thus forming a star-of-stars network, we get a modular andscalable high-bandwidth network. The deterministic properties of thenetwork are theoretically analyzed for both intra-cluster and inter-clustercommunication, and computer simulations of intra-cluster communicationare reported. Also, an overview of high-performance fiber-opticcommunication systems is presented.</p>

<p>High-performance embedded systems communicating heterogeneous traffic with high bandwidth and strict timing requirements are in need of more efficient communication solutions. This thesis proposes two multi-wavelength passive optical networks able to meet these demands. The networks are based upon a single-hop star topology with an Arrayed Waveguide Grating (AWG) placed in the centre. The intended application areas for the two networks are short range embedded communication systems like System Area Networks (SANs) and router architectures with electronic queuing. The AWG’s attractive property of spatial wavelength reuse, as well as the combination of fixed-tuned and tuneable transceivers in the end nodes, enables simultaneous control and data traffic transmission. This, in turn, makes it possible to support heterogeneous traffic with both hard and soft real-time constraints.</p><p>Additionally, two Medium Access Control (MAC) protocols, one for each network solution, are developed. Traffic scheduling is centrally controlled by a node, the protocol processor, residing together with the AWG in a hub. All nodes use Earliest Deadline First (EDF) scheduling and communicate with the protocol processor through physical control channels. A case study, including simulations, in the field of Radar Signal Processing (RSP) and simulations using periodic real-time traffic are conducted for the two application areas respectively, showing very good results. Further, a deterministic real-time analysis is conducted to provide throughput and delay guarantees for hard real-time traffic and an increase in guaranteed traffic is achieved through an analysis of existing traffic dependencies in a multichannel network. Simulation results incorporating the traffic dependency analysis indicate a considerable increase in the possible guaranteed throughput of hard real-time traffic.</p>

No description available.

Membrane filtration of protein solutions is influenced by a wide range of processing and physicochemical conditions. Monitoring and optimizing membrane filtration may have advantages for achieving, in a cost effective manner, improved bioproduct purification and membrane performance which is relevant to pharmaceutical and biochemical applications. The motivation of this work was to examine the feasibility of applying two-dimensional fluorescence spectroscopy in conjunction with chemometric techniques for monitoring and possibly optimizing the performance of membrane processes. Preliminary work focused on assessing the use of multivariate calibration tools in conjunction with the sensitivity of intrinsic protein fluorescence towards changes in environmental conditions was to predict protein concentration and aggregation behavior. A model protein, β-lactoglobulin (β-LG), was used as a first simple case scenario. Results showed very good agreement between the fluorescence based predictions and measurements obtained by HPLC and gravimetric analysis regardless of the conditions. PLS analysis of excitation-emission matrices revealed unique spectral fingerprints that are most likely associated with the heat-induced denaturation and aggregation. Standard Normal Variate, a signal preprocessing and filtering tool, was shown to have a significant effect on enhancing the predictive accuracy and robustness of the PLS model as it reduced the effect of instrumental noise. The methodology was then extended to a two-component protein system consisting of α- lactlalbumin (α-LA) and β-lactoglobulin (β-LG). The process of thermal induced aggregation of β-LG and α-LA protein in mixtures, which involves the disappearance of native-like proteins, was studied under various treatment conditions including different temperatures, pH, total initial protein concentration and proportions of α-LA and β-LG. A Partial Least Squares (PLS) regression algorithm was used to correlate the concentrations of α-LA and β-LG to the fluorescence spectra obtained for mixtures.The results illustrated that multivariate models could effectively deconvolute multiwavelength fluorescence spectra collected for the protein mixtures and thereby provide a fairly accurate quantification of respective native-like α-LA and β-LG despite the significant overlap between their emission profiles. It was also demonstrated that a PLS model could be used as a black-box prediction tool for estimating protein aggregation when combined with simple mass balances. Ultrafiltration experiments of the whey protein isolate solutions were carried out in dead-end filtration mode and fluorescence measurements of permeate and retentate solutions were acquired in synchronous scanning mode using a fiber optic probe. By implementing a dilution strategy for the retentate side, the fluorescence based PLS model encompassed a low protein concentration range where fluorescence was not expected to be significantly influenced by concentration-dependent interferences. It was also demonstrated that synchronous spectra can provide good predictions and consequently the use of the full spectrum may not be necessary for monitoring with corresponding savings in acquisition time. Membrane performance variables that are difficult to measure, such as individual protein transmission and membrane selectivity could be estimated directly from fluorescence-based predictions of protein concentrations in the retentate and permeate streams. Multiwavelength light scattering spectra, acquired using the fiber optic probe, were shown to be a useful indicator for protein self-association behavior, which is known to influence the membrane filtration. High fouling potential were observed for protein solutions that exhibited significant Rayleigh scattering. A predictive PLS model for estimating protein aggregation from Rayleigh scattering measurements was developed and it was tested by using molecular weight experimental values obtained from the literature. Although this comparison was only partial due to the limited amount of molecular weight data available, the findings verified the possibility of estimating the aggregate size from multiwavelength Rayleigh scattering spectra acquired using a conventional spectrofluorometer. Thus, the results implied that both intrinsic fluorescence and light scattering multiwavelength measurements could provide complementary information about the filtration process.

Membrane filtration of protein solutions is influenced by a wide range of processing and physicochemical conditions. Monitoring and optimizing membrane filtration may have advantages for achieving, in a cost effective manner, improved bioproduct purification and membrane performance which is relevant to pharmaceutical and biochemical applications. The motivation of this work was to examine the feasibility of applying two-dimensional fluorescence spectroscopy in conjunction with chemometric techniques for monitoring and possibly optimizing the performance of membrane processes. Preliminary work focused on assessing the use of multivariate calibration tools in conjunction with the sensitivity of intrinsic protein fluorescence towards changes in environmental conditions was to predict protein concentration and aggregation behavior. A model protein, β-lactoglobulin (β-LG), was used as a first simple case scenario. Results showed very good agreement between the fluorescence based predictions and measurements obtained by HPLC and gravimetric analysis regardless of the conditions. PLS analysis of excitation-emission matrices revealed unique spectral fingerprints that are most likely associated with the heat-induced denaturation and aggregation. Standard Normal Variate, a signal preprocessing and filtering tool, was shown to have a significant effect on enhancing the predictive accuracy and robustness of the PLS model as it reduced the effect of instrumental noise. The methodology was then extended to a two-component protein system consisting of α- lactlalbumin (α-LA) and β-lactoglobulin (β-LG). The process of thermal induced aggregation of β-LG and α-LA protein in mixtures, which involves the disappearance of native-like proteins, was studied under various treatment conditions including different temperatures, pH, total initial protein concentration and proportions of α-LA and β-LG. A Partial Least Squares (PLS) regression algorithm was used to correlate the concentrations of α-LA and β-LG to the fluorescence spectra obtained for mixtures.The results illustrated that multivariate models could effectively deconvolute multiwavelength fluorescence spectra collected for the protein mixtures and thereby provide a fairly accurate quantification of respective native-like α-LA and β-LG despite the significant overlap between their emission profiles. It was also demonstrated that a PLS model could be used as a black-box prediction tool for estimating protein aggregation when combined with simple mass balances. Ultrafiltration experiments of the whey protein isolate solutions were carried out in dead-end filtration mode and fluorescence measurements of permeate and retentate solutions were acquired in synchronous scanning mode using a fiber optic probe. By implementing a dilution strategy for the retentate side, the fluorescence based PLS model encompassed a low protein concentration range where fluorescence was not expected to be significantly influenced by concentration-dependent interferences. It was also demonstrated that synchronous spectra can provide good predictions and consequently the use of the full spectrum may not be necessary for monitoring with corresponding savings in acquisition time. Membrane performance variables that are difficult to measure, such as individual protein transmission and membrane selectivity could be estimated directly from fluorescence-based predictions of protein concentrations in the retentate and permeate streams. Multiwavelength light scattering spectra, acquired using the fiber optic probe, were shown to be a useful indicator for protein self-association behavior, which is known to influence the membrane filtration. High fouling potential were observed for protein solutions that exhibited significant Rayleigh scattering. A predictive PLS model for estimating protein aggregation from Rayleigh scattering measurements was developed and it was tested by using molecular weight experimental values obtained from the literature. Although this comparison was only partial due to the limited amount of molecular weight data available, the findings verified the possibility of estimating the aggregate size from multiwavelength Rayleigh scattering spectra acquired using a conventional spectrofluorometer. Thus, the results implied that both intrinsic fluorescence and light scattering multiwavelength measurements could provide complementary information about the filtration process.

Mycobacterium tuberculosis, the bacterium that causes tuberculosis, has an incubation period ranging from a few months to several years following infection via inhalation into the lungs. Whole body fluorescence scanners are used to image and monitor the growth of fluorescent protein expressing strains of M. tuberculosis in the lungs of animal models. Accurate quantitative analysis of bacterial growth during the early stages of infection inside lungs remains elusive, due to tissue absorption and scattering of photons emitted by the low numbers of bacteria deep in tissue. Fiber optic micro-endoscopy is uniquely suited to provide a novel solution to this problem by delivering light excitation directly to and collecting fluorescence from the infection site located in the lungs of an animal model, thereby enabling detection of fluorescent bacteria during the early stages of infection. In this thesis, I present a contact probe fiber bundle fluorescence micro-endoscope with a range of LED based excitation wavelengths, 4 μm resolution, a 750 μm field of view, and a 1 mm outer diameter. This system has detected tdTomato and GFP expressing Bacillus Calmette-Guérin (BCG) bacteria in vitro. Additionally, images of bacterial regions of infection obtained in mice subcutaneously infected with tdTomato expressing bacteria at concentrations ranging from 106 to 101 Colony Forming Units (CFU) and intra-tracheally infected mice at 106 CFU demonstrate the micro-endoscope’s capability to detect and resolve regions of bacterial infection in vivo. By relaying the bacterial fluorescence image from the infection site to an external detector, we are able to increase the sensitivity to early stages of infection.

The main purpose of the optical fiber sensing technology is to detect perturbation of physical fields. By means of some demodulating scheme, we can extract the real signal from those light beams which modified by physical fields. In the thesis, we proposed a configuration of modified Sagnac Interferometer as a sensing system. The optical sensing and demodulation system are exploited separately. Next, we study the advantages and disadvantages of the configuration. Besides, we are also measured the sensitivity and dynamic range. The sensing system used a low coherence light source to reduce cost. This system also improves the shortage of a Sagnac Interferometer which has a blind point in the middle position. In addition, the structure is easily implemented and can detect weak signal in a high noisy water environment. For matching the main structure, we make many kinds of sensing heads for detecting signals under water. We also use the mathematical model as the base of the theory. The dynamic range is 40 dB and the sensitivity is -231.47 dB re V/uPa.

Thesis (M.S. in Information Technology Management)--Naval Postgraduate School, March 2004. / Thesis advisor(s): Norman F. Schneidewind. Includes bibliographical references (p. 51). Also available online.

No description available.