In this study, the effects of oxygen transfer conditions on the synthesis of the enzyme benzaldehyde lyase as intracellular in recombinant E. coli BL21 (DE3) pLysS was investigated sistematically and a comprehensive model was developed to determine benzaldehyde lyase activity. For this purpose, the research program was carried out in mainly two parts. In the first part of study, the effects of oxygen transfer together with the mass transfer coefficient (KLa), enhancement factor E (=KLa/KLao), volumetric oxygen transfer rate, volumetric and specific oxygen uptake rates, mass transfer and biochemical reaction resistances / moreover, the variation in product and by-product distribution, specific substrate uptake rates, yield and maintenance coefficient were investigated in the pilot scale batch bioreactor at QO/VR = 0.5 vvm and agitation rates of N= 250, 500, 625, and 750 min-1, and dissolved oxygen levels DO= 20%, 40% conditions, while medium components were CGlucose= 8.0 kg m-3, C(NH4)2HPO4= 5.0 kg m-3 and salt solution at controlled pHc=7.2. The highest cell concentration and benzaldehyde lyase activity were obtained at DO=40% condition as 3.0 kg m-3 and A=1095 Ucm-3, respectively. v Then a mathematical model was proposed to estimate benzaldehyde lyase activity as function of time, agitation rate, cell concentration, dissolved oxygen concentration, and by-product concentration with reasonable accuracy.

All but the simplest physical systems contains mechanical joints. The behavior of these joints is sometimes the dominant factor in over all system behavior. The potential for occurence of microslip and macroslip normally makes the behavior of joints non-linear. Accurate modeling of joints requires a non-linear ramework. As clamping pressures are typically random ad variable, the behavior of the joints becomes random. Joint geometries are random along with other unknowns of the joints. Two different methods for measuring the energy dissipation are explained. In the experimental method, the energy dissipation of a non-linear joint is calculated from the slope of the envelope of the time response of acceleration. The simulation work is carried out by considering a smooth hysteresis model with the help of Matlab programming. Finally, the parameters are extracted for a specific non-linear system by comparing analytical and experimental results. / 0736988322

Electroporation is a methodology for the introduction of drugs and genes into cells. This technique works by reducing the exclusionary nature of the cell membrane [125, 129, 186, 189]. Electroporation has successfully been used in electrochemotherapy and electrogenetherapy [57, 68, 86, 87, 110, 112, 131]. The two major components of electroporation are an induced transmembrane potential and the motion of the deliverable through a compromised cell membrane into the target cell [38, 55, 62, 114, 131]. These two components are both dependent on the electrophoretic motion of charged species in an applied electric field [45, 64, 75, 77, 177]. Currently, the methods outlined for understanding electroporation have been focused on either a phenomenological perspective, e.g. what works, or modeling the electric fieldstrength in certain regions [12, 56, 87, 129, 146, 204, 205]. While this information is necessary for the clinician and the laboratory scientist, it doesn't expand the understanding of how electric field mediated drug and gene delivery works or EFMDGD. To increase the understanding of EFMDGD, new models are required that predict the motion of ions and deliverables through tissues to target areas [75, 77]. This document examines the design and creation of an electric field mediated drug and gene delivery model, EFMDGDM. Two example scenarios, ionic motion in tissues and gel electrophoresis, are examined in depth using the EFMDGDM. The model requires tuning for each scenario but only utilizes experimental parameters and one tunable parameter that is computed from regressed experimental data. The EFMDGDM successfully describes the two examples. Future work will incorporate the EFMDGDM as the backbone of an electric field mediated drug and gene delivery modeling package, EFMDGDMP.

A coupled, three-dimensional, time-dependent numerical model of water circulation, spectral light, plankton dynamics, nutrient/CDOM loadings, and zooplankton grazing provided an assessment of the factors affecting the growth and maintenance of red tides on the west Florida shelf (WFS). The coupled biophysical model consisted of state variable quantities for temperature, salinity, horizontal/vertical velocity components, turbulent diffusion, spectral light, colored dissolved organic matter (CDOM), dissolved organic and inorganic carbon, particulate silica, four dissolved inorganic nutrient pools (nitrate, ammonium, phosphate, and silicate), and four phytoplankton groups (diatoms, microflagellates, non-toxic dinoflagellates, and the red tide organism Karenia brevis). The model also included a complex grazing scheme that utilized thirteen different zooplankton groups to explore the effects of selective herbivory, feeding periodicity, diel vertical migration, fecal pellet egestion, and ammonium/phosphate excretion within a diverse zooplankton community. Over the shelf and slope of the eastern Gulf of Mexico, from the Mississippi River delta to the Florida Keys, four cases of the model were run during August -- November to explore the dynamics of red tide maintenance with respect to: (1) no refuge from grazing for K. brevis; (2) grazer avoidance of K. brevis during CDOM shading; (3) grazer avoidance of K. brevis in Case II waters; and (4) increased grazing stress on K. brevis competitors. NEGOM and ECOHAB data sets during July -- November 1999 were used to establish the initial/boundary conditions and provided validation data for the coupled model as well. Model results indicate that the red tide of 5.9 x 10 6 cells L-1 witnessed offshore Sarasota, Florida on 07 October 1999 was initiated by an inoculum of K. brevis observed in near-bottom waters above the 30 m isobath offshore Sarasota on 31 August 1999. Flowfields measured at moored ADCPs, observations from AVHRR satellite imagery, and west Florida shelf circulation models indicate that conditions of coastal upwelling existed during the period of bloom development, such that the K. brevis inoculum was delivered to the coast in the bottom Ekman layer. As a shade-adapted species capable of vertical migration, K. brevis cells aggregated near the bottom in order to escape photo-inhibitive light intensities in the overlying water column during the day and harvested the recycled nitrogen excreted by zooplankton grazers. This concomitant relaxation of light inhibition and nitrogen-limitation ultimately led to the growth and maintenance of the red tide, constrained in near-bottom waters during much of the day and preferentially advected inshore as a result of coastal upwelling. As K. brevis was advected inshore, self-shading, CDOM, and suspended inorganic particulates all contributed to the prevention of photo-inhibitive light intensities that, in combination with the excretion of recycled ammonium, ultimately led to the maintenance of a significant red tide at the coast.

The growth of a neuronal dendritic tree depends on the neuron’s internal state and the environment within which it is situated. Different types of neuron develop dendritic trees with specific characteristics, such as the average number of terminal branches and the average length of terminal and intermediate segments. A key aspect of the growth process is the construction of the microtubule cytoskeleton within the dendritic tree. Neurite elongation requires assembly of microtubules from free tubulin at the growth cone. The stability of microtubule bundles is an important factor in determining how likely it is for a growth cone to split to form new daughter branches. Microtubule assembly rates and bundle stability are controlled by microtubule-associated proteins, principally MAP2 in dendrites. Extending previous work (Hely et al, J. Theor. Biol. 210:375-384, 2001) I have developed a mathematical model of neurite outgrowth in which elongation and branching rates are determined by the phosphorylation state of MAP2 at the tips of each terminal branch. Tubulin and MAP2 are produced in the cell body and transported along the neurite by a combination of diffusion and active transport. Microtubule (dis)assembly at neurite tips is a function of tubulin concentration. The rate of assembly depends on the amount of unphosphorylated MAP2 bound to the microtubules and linking them together. Phosphorylation of MAP2 destroys its linking capability and destabilises the microtubule bundles. Each terminal has a probability of branching that depends on the phosphorylation of MAP2 which, in turn, is a function of calcium concentration. Results from this model show that changes in the (de)phosphorylation rates of MAP2 affect the topology of the final dendritic tree. Higher phosphorylation promotes branching and results in trees with many short terminal branches and relatively long intermediate segments. Reducing phosphorylation promotes elongation and inhibits branching.

Models based on micro-simulation of traffic flows have proven to be useful tools in the study of various traffic systems. Today, there is a wealth of traffic microsimulation models developed for freeway and urban street networks. The road mileage is however in many countries dominated by rural highways. Hence, there is a need for rural road traffic simulation models capable of assessing the performance of such road environments. This thesis introduces a versatile traffic micro-simulation model for the rural roads of today and of the future. The developed model system considers all common types of rural roads including effects of intersections and roundabouts on the main road traffic. The model is calibrated and validated through a simulation study comparing a two-lane highway to rural road designs with separated oncoming traffic lanes. A good general agreement between the simulation results and the field data is established. The interest in road safety and the environmental impact of traffic is growing. Recent research has indicated that traffic simulation can be of use in these areas as well as in traditional capacity and level-of-service studies. In the road safety area more attention is turning towards active safety improving countermeasures designed to improve road safety by reducing the number of driver errors and the accident risks. One important example is Advanced Driver Assistance Systems (ADAS). The potential to use traffic simulation to evaluate the road safety effects of ADAS is investigated in the last part of this thesis. A car-following model for simulation of traffic including ADAS-equipped vehicles is proposed and the developed simulation framework is used to study important properties of a traffic simulation model to be used for safety evaluation of ADAS. Driver behavior for ADAS-equipped vehicles has usually not been considered in simulation studies including ADAS-equipped vehicles. The work in this thesis does however indicate that modeling of the behavior of drivers in ADAS-equipped vehicles is essential for reliable conclusions on the road safety effects of ADAS. / <p>Report code: LiU-Tek-Lic-2005:60.</p>

After reviewing the documents about the studies of hydrate formation kinetics in the world, this paper analyzed the process of hydrate formation on a suspended water droplet, which was based on the hydrate formation with water spay method, proposed a corresponding mathematical model, and solved it. Afterwards, the discussion about this model was presented. The results indicated that equilibrium time diminished with the decrease of the water droplet radius, and prolonged with the increase of sub-cooling degree, the reaction time for the second period reduced with the increase of subcooling degree, but was free from the effect of the variation of the water droplet size. The first period of the hydration on the water droplet was quite short, while the second period was considerably longer. Therefore, shortening the duration time of the second period of hydration was obviously able to accelerate the hydrate formation on the water droplet.

Lo scopo principale di questa ricerca è stato di monitorare la concentrazione di nitrati, dell'erbicida terbutilazina e di un suo metabolita, la desethylterbuthylazina, in acque sotterranee superficiali, secondo le normali pratiche agronomiche in differenti aree italiane rappresentative della coltura maidicola. Il primo passo è stato identificare i siti di monitoraggio, quindi è stata creata una procedura generale al fine di individuare aree rappresentative per il mais in Italia. Dentro tali aree sono stati selezionati dei siti di: 4 in Lombardia, 2 in Emilia Romagna, 2 in Veneto, 2 in Piemonte e uno in Friuli-Venezia Giulia. In Aprile 2005 il monitoraggio ha avuto inizio e i campionamenti sono stati eseguiti ogni due mesi. L'indice “IDPR”, strumento per la mappatura della vulnerabilità a livello regionale e nazionale, è stato applicato alle aree oggetto di studio. L'indice riflette l'influenza che le formazioni geologiche del sottosuolo hanno sullo scorrimento superficiale e sull'infiltrazione. L'analisi della probabilità di distribuzione dei risultati ha mostrato che una bassa probabilità di superare i limiti fissati per legge, questa probabilità è risultata più alta per il metabolita. Le concentrazioni dei nitrati nelle acque sotterranee sono risultate molto basse. Inoltre, è stato applicato un modello matematico (MACRO vs 5.1) di previsione che calcola la percolazione dei pesticidi. / The main aim of the research was to monitor the concentrations of nitrates, the herbicide terbuthylazine and its products of the environmental degradation, desethyl-terbuthylazine, in shallow groundwater, according to the normal agricultural practices in different Italian areas representative of maize crop. The first step was to identify the monitoring sites, therefore it was necessary to create a general procedure to individuate maize representative areas in Italy. Inside these area 11 monitoring sites were selected: 4 in Lombardy, 2 in Emilia Romagna, 2 in Veneto, 2 in Piedmont and one in Friuli-Venezia Giulia. In April 2005 the monitoring started. Groundwater samplings were carried out every two months. The IDPR index, a tool for national and regional vulnerability mapping, was applied. The index reflects the influence of the subsurface geological formations on the surface water runoff or infiltration. The distribution probability analysis of the results showed that there was a very low probability of exceeding the limit fixed by law, this probability was higher for the metabolite. The greater probability of exceed the 0.1 μg/L occurred in two sites, both irrigated with basin irrigation system. Nitrate concentrations resulted to be very low in shallow groundwater. Moreover, it was used a mathematical model which calculate the leaching of pesticides (MACRO 5.1).

Driving simulators and microscopic traffic simulation are important tools for making evaluations of driving and traffic. A driving simulator is de-signed to imitate real driving and is used to conduct experiments on driver behavior. Traffic simulation is commonly used to evaluate the quality of service of different infrastructure designs. This thesis considers a different application of traffic simulation, namely the simulation of surrounding vehicles in driving simulators. The surrounding traffic is one of several factors that influence a driver's mental load and ability to drive a vehicle. The representation of the surrounding vehicles in a driving simulator plays an important role in the striving to create an illusion of real driving. If the illusion of real driving is not good enough, there is an risk that drivers will behave differently than in real world driving, implying that the results and conclusions reached from simulations may not be transferable to real driving. This thesis has two main objectives. The first objective is to develop a model for generating and simulating autonomous surrounding vehicles in a driving simulator. The approach used by the model developed is to only simulate the closest area of the driving simulator vehicle. This area is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to a microscopic model which includes sub-models for driving behavior, while vehicles in the outer regions are updated according to a less time-consuming mesoscopic model. The second objective is to develop an algorithm for combining autonomous vehicles and controlled events. Driving simulators are often used to study situations that rarely occur in the real traffic system. In order to create the same situations for each subject, the behavior of the surrounding vehicles has traditionally been strictly controlled. This often leads to less realistic surrounding traffic. The algorithm developed makes it possible to use autonomous traffic between the predefined controlled situations, and thereby get both realistic traffc and controlled events. The model and the algorithm developed have been implemented and tested in the VTI driving simulator with promising results.

Driving simulators are used to conduct experiments on for example driver behavior, road design, and vehicle characteristics. The results of the experiments often depend on the traffic conditions. One example is the evaluation of cellular phones and how they affect driving behavior. It is clear that the ability to use phones when driving depends on traffic intensity and composition, and that realistic experiments in driving simulators therefore has to include surrounding traffic. This thesis describes a model that generates and simulates surrounding vehicles for a driving simulator. The proposed model generates a traffic stream, corresponding to a given target flow and simulates realistic interactions between vehicles. The model is built on established techniques for time-driven microscopic simulation of traffic and uses an approach of only simulating the closest neighborhood of the driving simulator vehicle. In our model this closest neighborhood is divided into one inner region and two outer regions. Vehicles in the inner region are simulated according to advanced behavioral models while vehicles in the outer regions are updated according to a less time-consuming model. The presented work includes a new framework for generating and simulating vehicles within a moving area. It also includes the development of enhanced models for car-following and overtaking and a simple mesoscopic traffic model. The developed model has been integrated and tested within the VTI Driving simulator III. A driving simulator experiment has been performed in order to check if the participants observe the behavior of the simulated vehicles as realistic or not. The results were promising but they also indicated that enhancements could be made. The model has also been validated on the number of vehicles that catches up with the driving simulator vehicle and vice versa. The agreement is good for active and passive catch-ups on rural roads and for passive catch-ups on freeways, but less good for active catch-ups on freeways.