The Mississippi River is considered the ultimate single channel meandering river. Five hundred km upstream from its mouth, about 25% of the river’s discharge is diverted into the Atchafalaya River. This diversion is controlled by the Old River Control structure, built by the US Army Corps of Engineers in stages since 1963, to stop the avulsion of the Mississippi River into the Atchafalaya. The study area is a 119 km sandy bedded reach near Old River Control that is highly impacted by engineering measures. Channel dimensions average 1,000 m wide with average thalweg depths of 23 m. The mean annual discharge is 15,000 m3s-1 with a water surface slope of 0.06 m per river mile. In a sandy bedded river, the effective discharge is the discharge which cumulatively transports the most sand. This study evaluates how the Old River Control structure has influenced an adjusting effective discharge between 1978 and 2011. The bed load component of sand transport is included by employing a novel, automated, cross-correlation technique. It was found that the upper limit for discharges that cumulatively transport 85% of the total sand load has decreased from 34,000 m3s-1 to 28,000 m3s-1 between 1978 and 2011. Sand transport from 1982 to 2011 occurred during progressively greater ratios of water discharge to the Atchafalaya River and corresponded to an aggradational trend in the nearby Mississippi River at Red River Landing stream gage. The combination of this sand transport trend and nearby channel aggradation is some indication that the diversion may not be stable and that the avulsion of the lower Mississippi River is ongoing. However, sand was transported at similar discharge ratios in the 1978 to 1982 and 2002 to 2011 periods. Future trends will reveal definitively if these findings indicate that the lower Mississippi River avulsion is continuing. Two aims are pursued by placing the effective discharge approach into the geomorphologic context of the study area. Ten zones are categorized by four distinct geomorphologic classes: meander, no islands; meander, geologic control; meander, islands and divided flow; and straight zones. One, these classes have merit for future research and are shown to be geomorphologically distinct in several ways: natural levee height and channel planform adjustment relationships, sinuosity and width to depth ratios, and bedform depth to height scaling. Two, this approach allows the comparison of the effective discharge to the study area’s geomorphology. Process-form linkages can be made between sediment transporting events and the three levels in a fluvial hierarchy: fluvial bedforms and channels, bars, and levees. Median grain size and channel position of sediment samples from these three levels were plotted on combined LiDAR and bathymetric derived cross- sections from specific geomorphologic zones. This analysis indicates that the fluvial hierarchy coincides with the stages of effective discharge but seems to scale to the elevation of natural levees. This study interjects a geomorphologic approach into the lower Mississippi River discourse and raises a number of interesting questions for further research. / text

Recent droughts and heat waves have revealed the vulnerability of some power plants to effects from higher temperature intake water for cooling. Climate projections estimate higher air temperatures in future years, indicating that these problems could increase. This research seeks to understand the magnitude of influence that higher temperatures will have on power plant effluent water temperatures to quantify a power plant's exposure to risk of de-rating induced by low or warm cooling water availability. The objective of this analysis is to help policymakers and plant operators plan for future electricity supplies without damaging the natural environment of the cooling reservoirs and rivers. This objective is met via assessment of water constraints associated with current technology, policy, and environmental conditions in two river basins, the Gulf Coast Basin in Texas and the Upper Mississippi River Basin in the Midwestern United States. Risk of reduced operations at these power plants associated with thermal discharge limits is then assessed by estimating intake and effluent water temperatures and comparing these estimates to current restrictions. Of the thirty-three plants analyzed, none are estimated to exceed effluent temperature limits within the study period of 2015 to 2035. However, twelve power plants could face increasing intake temperatures, leading to potential issues with cooling efficiency. Fourteen plants could discharge slightly higher effluent temperatures, possibly influencing the ecosystem of the return water body upon discharge beyond today's impacts. To help with planning for future issues, this analysis also identifies many of the ways by which power plants mitigate issues with low water levels and high temperatures. Designing plants for potentially scarce water resources and making policies that protect water supplies and support energy resources could be beneficial in coming years. This research is intended to inform that objective. / text

An exploratory study of the geomorphology of Florida's springs was conducted using morphometric analysis. Spatial datasets for spring locations, elevation data, physiography, geology and hydrography were acquired for incorporation and analysis with GIS technology. ArcGIS 9 was used to measure certain morphometric parameters from the spatial data for Florida's springs. Other Parameters representing physical and dimensional characteristics of the springs were acquired from FGS Bulletin 66, Springs of Florida. All measured and collected data was compiled into a usable morphometric database. The data is described statistically and summarized according to the spatial distribution of Florida's springs with respect to geology and landforms. This examination is carried out at two different scales; 1) the entire population of Florida's 754 springs is examined with emphasis placed upon geology, physiography, and elevation, 2) a subset of 102 springs that is deemed to be a representative sample is examined according to all morphometric parameters. It was concluded that the presence of karst terrain at the majority of the spring sites that were examined in this study is the prevailing factor that has influenced where springs have resurged in Florida. This was observed at both scales in the study. It is also concluded that spring sites in Florida are strongly linked to lower elevations, and therefore that elevation also influences their distribution. Suggestions for future research are posed, including specific ways in which the current methodology can be expanded upon and improved.

Η παρούσα διπλωματική εργασία χωρίζεται σε έξι κεφάλαια, καθένα από τα οποία περιγράφεται παρακάτω. Στο πρώτο κεφάλαιο , που ονομάζεται "Θεωρία του laser", περιγράφονται οι γενικές αρχές λειτουργίας του laser. Επιπλέον αναφέρονται τα κύρια μέρη του καθώς και οι τρόποι δημιουργίας του φαινομένου laser. Ενώ τέλος γίνεται αναφορά στα χαρακτηριστικά της δέσμης laser. Στο δεύτερο κεφάλαιο, "Θεωρία του πλάσματος", γίνεται λόγος για τον τρόπο δημιουργίας του πλάσματος, τις εφαρμογές του και μελετόντε κάποια ιδιαίτερα χαρακτηριστικά του. Το τρίτο κεφάλαιο αναφέρεται στα excimer laser, την λειτουργία τους και τις ιδιαιτερότητές τους συγκρινόμενα με άλλους τύπους laser. Επιπλέον δίνεται μεγαλύτερη έμφαση στο laser XeCl όπου μελετάται το μόριο του XeCl* καθώς και ο τρόπος δημιουργίας του. Στο τέταρτο κεφάλαιο γίνεται εκτενής αναφορά σε ένα απλοποιημένο θεωρητικό μοντέλο το οποίο δημιουργήθηκε για μελέτη της προσομοίωσης μιας εκκένωσης που πραγματοποιείται μέσα στο ενεργό μέσο προκειμένου να γίνει η αντιστροφή πληθυσμού. Αυτό το θεωρτικό μοντέλο περιλαμβάνει το ηλεκτρικό κύκλωμα που παρέχει ενέργεια στο ενεργό μέσο και στην συνέχεια γίνεται ανάλυση της συμπεριφοράς της εκκένωσης ώστε να επιλυθούν οι εξισώσεις συνέχειας. Στο πέμπτο κεφάλαιο, που ονομάζεται "Αριθμητικό μοντέλο" παρουσιάζονται οι μαθηματικές διεργασίες που χρησιμοποιήθηκαν με στόχο να επιλυθεί το θεωρητικό μοντέλο το οποίο αναπτύχθηκε στο κεφάλαιο τέσσερα. Τέλος στο έκτο κεφάλαιο παρουσιάζονται τα αριθμητικά αποτελέσματα που είναι προϊόν της επίλυσης του αριθμητικού μοντέλου του πέμπτου κεφαλαίου. Επίσης γίνεται σχολιασμών αυτών των αποτελεσμάτων και σύγκρισή τους με αναμενόμενα ή πειραματικά άλλων μελετών. / -

The basin factor is a hydrologic parameter that represents the overall impedance to flow of a watershed in the PC-Hydro peak discharge model for small ( < 10 mi2) semi-arid watersheds in Pima County, Arizona. To improve peak discharge estimates and provide validation of the basin factor as a physically-based parameter, basin factor values were "back-calculated" for return period and observed events on six undeveloped rangeland watersheds and correlated with Manning's n roughness coefficients, rainfall intensities, and hydraulic radii. Observed basin factor values displayed a positive trend with observed peak discharge. The results suggest that the correlated variables can predict the basin factor on small undeveloped sub-basins in Pima County and the basin factor is measurable as a physical parameter. Empirical models for basin factor prediction are proposed. The study may also be useful for estimating hydraulic roughness in hydrologic methods such as the kinematic wave time of concentration equation.

Since deinstitutionalization many patients, instead of remaining in the community, revolve through the doors of psychiatric facilities resulting in the "Revolving Door Syndrome". Hence a biopsychosocial evaluation of readmissions was undertaken to see what processes came into play once a patient was discharged from a mental hospital and subsequently readmitted. Seventy Indian patients admitted to the Midlands hospital complex, Pietermaritzburg were interviewed and the data was collected. This comprised 40 readmissions and a control group of 30 first admissions. The diagnosis was made according to DSM-III-R. The results obtained were statistically analyzed and a chi square analysis was done to ascertain if there were any significant differences between the 2 groups. The following were the major findings 1. Most of the patients were in age group 20-29 years. 2. There was a preponderance of males in both groups. 3. Most of the patients in the readmitted group were unemployed and were receiving a disability grant. 4. The majority of patients was single or separated. 5. Most of the patients were discharged on a combination of drug and depot preparation. 6. A large percentage had two and more previous admissions. 7. Length of stay was less than 1 month in a large number of patients. 8. Community tenure was less than 1 year in most of the patients. 9. Even though the majority of patients reported regular attendance, a fair percentage reported attendance at the community clinic. 10. The reason for readmission was mainly aggressive behaviour and aggressive behaviour associated with substance abuse. 11. The discharge diagnosis was schizophrenia in a large number of patients. This study has several important implications for the community care of the patient and various recommendations are made to curtail the revolving door, as follows : 1. There is an urgent need for community based resources. eg. sheltered workshops, supervised housing, industrial and occupational therapy, halfway houses and day hospitals, which would help the chronically mentally ill patients lead more meaningful lives following discharge. 2. The family of the chronically mentally ill patient needs to be actively involved in the management of these patients and mental health workers must solicit the family's support, by educating them about schizophrenia, helping them to increase coping mechanisms and to decrease stress. It is recommended that support groups be held in the community for the families of patients. 3. The patient's family needs to be advised that when the patient show signs of decompensation, they should take the patient to the community clinic, rather than to the District Surgeon to avoid unnecessary rehospitalization. 4. The importance of maintenance medication cannot be overemphasised. There is a need to change the attitude of the patient and family with regard to their negative attitude about medication. 5. The high rate of readmission due to aggressive behaviour (which is aggravated by substance abuse) needs intervention. Substance abuse groups must be held in the community and the community needs to be educated about the consequences of substance abuse in the mentally ill. / Thesis (M.Med.)-University of Natal, 1993.

Šio darbo pagrindinis tikslas − įvertinti radioaktyviųjų teršalų paplitimą atmosferoje ir nusėdimą, bei įvertinti teršalų žalą aplinkai ir žmonėms. Tam tikslui pasiekti, šiame darbe buvo: 1.išanalizuoti pagrindiniai radioaktyviųjų teršalų paplitimo būdai; 2.supažindinta su teisės aktais ribojančiais radionuklidų išmetimą į aplinką; 3.įvertinti labiausiai žmonių sveikatą įtakojančių radionuklidų ir sklidimą atmosferoje ir nusėdimą. / In Lithuania we have a very important object from the point of energetics. It’s atomic power − station of Ignalina. It is work safety aspects worry so the themes of the graduate work have been chosen for this clean reason. The base of the work is to evaluate the damage of the radiological nuclides and to the environment and people and their discharge amounts the atmosphere, if it doesn’t exceed allowable norms, witch are regulated by the laws of Lithuania Republic. Willing to introduce you to this theme the following objectives were defined: 1.The main ways of radiological pollutants discharge into the atmosphere have been analyzed; 2.Have been familiarized with the main norms of radiological safety and the limitation of the discharge of radio nuclides into the atmosphere from the objects of atomic energetics; 3.According to the push − button program of environment pollution “ Hysplit ” the distribution of the radiological nuclides in the atmosphere has been denoted; 4.According to the results having been done by the program “ Hysplit “, the diagram of the dependence of the nuclides and on time has been delineated. It is clear that the atmosphere doesn’t exceed allowable norms of the laws of Lithuania Republic. It’s even lower than allowable norms per day. In conclusion, having all the objectives of this work analyzed it becomes clear that the amounts of the nuclides and witch gets into the atmosphere doesn’t damage our organisms and environment.

This work examines the role of charge redistribution in the self-discharge of electrochemical capacitor electrodes. Electrochemical capacitors are charge storage devices which have high power capability and a long cycle life, but have a low energy density compared to other devices, coupled with a high rate of self-discharge which further diminishes the available energy. The mechanisms of self-discharge in electrochemical capacitors are poorly understood, and it is important to gain a better understanding of the electrode processes which lead to self-discharge, in order to minimize self-discharge and enhance electrochemical capacitor performance. To learn more about charge redistribution and its role in the self-discharge of electrochemical capacitors, multiple self-discharge experiments were performed on carbons with various surface areas/pore structures and in various electrolytes. Charge redistribution was also examined in a model pore (a transmission line circuit based on de Levie?s model of a porous electrode) and results from this model were compared to the self-discharge of a high surface-area carbon. Results demonstrate that charge redistribution is a major component of the self-discharge in high surface-area carbons. Results also indicate that charge redistribution requires a much longer time than previously thought (tens of hours rather than minutes) which further highlights the importance of charge redistribution during self-discharge. Therefore when performing mechanistic studies of self-discharge in electrochemical capacitors, it is important that effects of charge redistribution are not neglected. The self-discharge profiles of various pore shapes were also examined using the model pore, and results emphasize the superiority of cone and cylindrically shaped pores, and the disadvantages of restrictive pore mouths and bottlenecks for high power applications.

Carbon nanotubes have become one of the most important building blocks critical to nanotechnology. Carbon nanotubes have attracted the interests of many scientists since their discovery due to their remarkable properties and have been widely used for various applications. However, the bottle neck in nanotube research has been the lack of a cheap, continuous and fast nanotube production method. This study concerns a reactor where nanotubes are continuously deposited on a carbon substrate using arc discharge at atmospheric pressure. This process appears to be the first to employ an arc discharge as the method for continuous mass deposition of nanotubes on a substrate. This nanotube deposition method eliminates the generic multistep process of nanotube deposition on substrates for its use in many applications. The effect of various parameters influencing growth and morphology of nanotubes on the substrate in the arc reactor (inter-electrode gap, atmosphere composition, current density, flushing, substrate type and speed and catalyst) have been systematically explored to optimise nanotube growth. The field emission properties of the nanotube laden substrate are studied for use and applicability as electron emitters. The nanotube samples demonstrated superior emission properties, low turn-on field and excellent current stability when put into applications such as a luminescent tube and an ionisation sensor. Theoretical modelling of the behaviour of a single nanotube during field emission was performed using finite element analysis software (COMSOL 3.2) to understand the effect of nanotube length, diameter, and vacuum gap on an individual nanotube. The results reveal that resistive heating (temperature) limits the maximum current carried by an individual nanotube. Furthermore, a new growth model is introduced to explain the formation of nanotubes from graphene fragments and nanocrystallites, due to polarisation of carbon species near the electrode surface suggesting that carbon vapour is unlikely to be responsible for nanotube growth.

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