by Andrew Loris Kurkjian. / Originally published as thesis (Dept. of Electrical Engineering and Computer Science, Ph.D., 1982). / Bibliography: p. 186-189. / Supported in part by the Advanced Research Projects Agency monitored by ONR under Contract N00014-81-K-0742 NR-049-506 Supported in part by the National Science Foundation under Grant ECS80-07102

Despite very extensive studies on molecular mechanisms of learning and memory formation it is little known about individual variation in the learning skills within a random animal population and about the differences in the brain biochemistry behind this variation. In the present study, we have focused on the expression and distribution of nitric oxide synthase (NOS), one of the molecules implemented in activity-dependent neuroplasticity, in the rat hippocampus, the structure critical for episodic memory in humans and animals. The aim of the present study was to investigate the differences in expression of three different NOS isoforms: neural (n), epithelial (e), and inducible (i), in four hippocampal subregions (CA1, CA3, DG, and hilus) between Wistar rats classified on the basis of their performance in partially baited 12-arm radial maze as &ldquo / good&rdquo / and &ldquo / poor&rdquo / learners. The NOS isoforms were visualized on coronal hippocampal sections using fluorescent immunohistochemistry technique and n- and eNOS images were processed using ImageJ software, while iNOS immunoreactivity (IR) was assessed by counting immunoreactive cells. In this study, overall hippocampal levels of nNOS were significantly higher than those of eNOS and iNOS. The level of n and eNOS was higher in CA1 compared to DG/hilus areas, but lower than that in CA3 region. The expression of iNOS was the highest in CA1 and the lowest in hilus region. nNOS IR was significantly higher in &ldquo / poor&rdquo / than in &ldquo / good&rdquo / learners but only in CA1 region. No significant between-group differences were found in eNOS expression. iNOS expression was higher in &ldquo / poor&rdquo / learners but it did not reach the required significance level.

Behavioral deficits caused by fetal-alcohol are well expressed in juvenile subjects but usually ameliorate with maturation. It suggests some kind of postnatal regeneration. The aim of the present study was to examine the potential correlation between behavioral recovery and the postnatal hippocampal development in the fetal-alcohol rats. This study included behavioral tests applied to juvenile and adult subjects, unbiased stereology to investigate changes in neuron numbers and hippocampal volumes, the postnatal tracing and analysis of the hippocampal principal neuron&rsquo / s morphology, investigation of age-dependent changes in the distribution of doublecortin-expressing neurons, and evaluation of synaptic development by assessing age-dependent changes in the regional immunoreactivity/expression of synaptophysin and PSD95. Rats have been exposed to ethanol throughout 7-21 gestation days with daily ethanol dose of 6g/kg delivered by intragastric intubation to the pregnant dams. The morphological characteristics were examined on postnatal days P1, P10, P30, P60, in hippocampal CA1, CA3, and DG subregions, in fetal-alcohol and control rats. Both, stereological and doublecortin-immunoreactivity data pointed towards a possibility of limited neurogenesis taking place during a protracted postnatal period not only in the germinal zones (SGZ and SVZ) but also in the hippocampal CA regions. Ethanol effect on postnatal hippocampal development was limited to marginally lower number of granular cells in DG on P30. It correlated with poorer cognitive performance in the fetal-alcohol group. The treatment effect on the morphology of hippocampal neurons was observed mainly in CA region at P1 and seemed to be attributed more to the intubation stress than the ethanol itself.

In this thesis, risk management methods are investigated in order to integrate risk management practices into the Turkish Aerospace industry. The research presents the sequence of risk management processes as identification of risk, analysis of risk, risk planning etc. Risk analysis methods named as Risk Ranking and Analytical Hierarchy Process (AHP) are investigated in order to improve reliability and safety of the systems or processes in the aerospace industry. The main aim of using risk ranking and AHP together is to translate the knowledge in the Turkish Aviation Industry to a tangible form with a quantitative approach and to prepare a basis for probabilistic risk analysis. Instrument Landing System (ILS) has been considered only in order to facilitate a demonstration how risk management can be done in this context. This study investigates and seeks to create awareness for risk management practices within Turkish Aviation industry.

In this study, the failure mechanism of the shore landslide which occured at Degirmendere coast region during 17 August 1999 Kocaeli (Izmit) - Turkey earthquake is analyzed. Geotechnical studies of the region are at hand, which reveal soil properties and geological formation of the region as well as the topography of the shore basin after deformations. The failure is analyzed as a landslide and permanent displacements are calculated by Newmark Method under 17 August 1999 Izmit record, scaled to a maximum acceleration of 0.4g. There are discussions on the main dominating mechanism of failure / landslide, liquefaction, fault rupture and lateral spreading. According to the studies, the failure mechanism is a seismically induced shore landslide also triggered by liquefaction and fault rupture, accompanied by the mechanism of lateral spreading by turbulence. A seismically induced landslide is discussed and modeled in this study. The finite element programs TELSTA and TELDYN are employed for static and dynamic analyses. Slope stability analyses are performed with the program SLOPE. The permanent displacements are calculated with Newmark Method, with the help of a MATLAB program, without considering the excess pore pressures.

Estimation of the ground motion parameters is extremely important for engineers to make the structures safer and more economical, so it is one of the main issues of Earthquake Engineering. Peak values of the ground motions obtained either from existing records or with the help of attenuation relationships, have been used as a useful parameter to estimate the effect of an earthquake on a specific location. Peak Ground Velocities (PGV) of a ground motion is used extensively in the recent years as a measure of intensity and as the primary source of energy-related analysis of structures. Consequently, PGV values are used to construct emergency response systems like Shake Maps or to determine the deformation demands of structures. Despite the importance of the earthquakes for Turkey, there is a lack of suitable attenuation relationships for velocity developed specifically for the country. The aim of this study is to address this deficiency by developing an attenuation relationship for the Peak Ground Velocities of the chosen database based on the strong ground motion records of Turkey. A database is processed with the established techniques and corrected database for the chosen ground motions is formed. Five different forms of equations that were used in the previous studies are selected to be used as models and by using nonlinear regression analysis, best fitted mathematical relation for attenuation is obtained. The result of this study can be used as an effective tool for seismic hazard assessment studies for Turkey. Besides, being a by-product of this study, a corrected database of strong ground motion recordings of Turkey may prone to be a valuable source for the future researchers.

Archery can be described as a static sport requiring strength and endurance of the upper body, in particular the shoulder girdle (Mann, 1984 / Mann &amp / Littke, 1989). To get a good record in an archery competition, one requires well-balanced and highly reproducible movements during the shooting (Nishizono, 1987). The bowstring is released when audible impetus is received from a device called &ldquo / clicker&rdquo / . As the fall of the clicker is an acoustic stimulus, it may evoke a sequence of potentials that can be recorded from the scalp of an archer. Auditory Evoked Potentials (AEPs) occur at different latencies and with various relations to the auditory stimuli. Therefore, the present study aims at investigating the Long-latency Auditory Evoked Potentials in Recurve Archery. Research questions can be stated briefly as follows: (1) What kind of Brain Potentials are Evoked by the Event (Fall of Clicker) during Archery Shooting? (2) Is there any significant difference between the characteristics of the potentials measured in laboratory conditions and during archery shooting? (3) Is there any significant difference between the successful and unsuccessful shots in terms of Auditory Evoked Brain Potentials? (4) Does Archery Shooting session have any effect on Auditory Evoked Brain Potentials? The subjects of the present study were 10 non-archers (N=6 males / N=4 females) for control trials and 15 archers (N=9 males / N=6 females) for archery shooting experiments. All subjects reported normal hearing, had medical histories free of significant neurological problems, and were not taking medication known to affect brain activity. Six different control paradigms have been created. Archery shootings were performed from 18 m that is official competition distance with target face.AEBPs were recorded 200 ms before and 800 ms after the trigger (fall of the clicker) over the vertex during the shots of each subject. Paradigm 1 and 5 was conducted just before and after the archery shooting to test the effect of archery shooting on AEBPs. The hit-area is defined as the rectangle between (x1, y1), (x1, y2), (x2, y1), (x2, y2) and the miss-area is the outer part of the hit-area on the target face. The preliminary analysis has shown that fall of the clicker evokes long latency auditory brain potentials with the latency of 100 msec and 200 msec. These responses are called as N1-P2 components. The means and standard deviations of both N100 and P200 amplitudes were as follows: N100 = 27,73 &plusmn / 16,82, P200 = -21,89 &plusmn / 20,46. The latencies of given brain responses were also summarized as: N100 = 141,93 &plusmn / 41,46 / P200 = 211,8 &plusmn / 43,97. N1 amplitude was significantly different in archery shooting than that of control conditions (p&lt / 0.05) except for trial 3, N1 latency was significantly different than that of trial 2 &ndash / 5 (p&lt / 0.05). P2 amplitude is significantly different in archery shooting than that of trial 6 (p&lt / 0.05). However, there was no significant difference in terms of P2 latency between archery shooting and control conditions (p&gt / 0.05). There was no significant difference between successful and unsuccessful shots in terms of N1-P2 components (p&gt / 0.05). An archery shooting session did not create any difference between these components recorded before and after the shot (p&gt / 0.05). Having higher N1 amplitudes during archery shooting can be explained by the known multi-component structure of this wave. Different lobes and regions of the brain can be active during the time of the scalp-recorded N1 and simultaneous involvement of several of these areas may be contributing to the electrical field recorded at scalp in the archery shooting paradigm.

In this thesis, the distribution and state of Posidonia oceanica meadows along the Turkish coast of the north eastern Mediterranean was investigated. The study area was a unique site due to the presence of eastern geographical limit of Posidonia oceanica meadows in Mediterranean Sea. It was aimed to assess the possible reasons of the absence and/or regression in relation to environmental changes. The study was conducted from September 2004 to January 2007 in 5 main regions between Anamur/Mersin and Samandag/Hatay. The regions were determined according to the presence/absence of Posidonia oceanica meadows / 1 region including the boundary meadow at the geographical distribution limit, 1 region western and 3 regions eastern to that boundary meadow. To describe the hydrological characteristics of the study area temperature, salinity and light were measured as abiotic descriptors. Additionally sedimentological analysis was carried out to check the suitability of the substrate type for Posidonia oceanica colonization. The main differences between the regions were found in temperature and light conditions. Both, the recordings of temperature loggers at 10 and 15 meter depths and the sea surface temperature retrieved from satellite (NOAA-AVHRR) showed that the eastern stations with no Posidonia oceanica meadows were warmer than the western stations. Consequently in this study the maximum tolerable temperature limit for Posidonia oceanica growth was determined as 28.4&deg / C from the data collected by the temperature loggers placed to natural meadows near to the boundary meadow. Generally, the whole study area had a limiting light condition for seagrass growth due to low penetration depths of the 10% of surface irradiation. This was a generalized minimum light requirement for growth of seagrasses. Especially in Mersin and Iskenderun bays the minimum required light level did not reached deeper than 10 meter depths in coastal stations. The biological parameters of the Posidonia oceanica meadows were investigated under 3 complementary methods in the first two regions. The structural descriptors were measured in-situ. The lowest shoot density and leaf lengths were found to be in boundary meadow. This meadow had also the lowest depth limit among other stations. The functional descriptors were examined by the lepidochronological and phenological analysis in laboratory. Most of the measurements varied either with respect to depth or among stations according to the abiotic factors of the stations. The lepidochronological cycles obtained from sheath thicknesses were further correlated with abiotic descriptors via a mathematical model. Finally, the first transplantation experiment of Posidonia oceanica along Turkish coasts has been conducted in 2 regions where presently no meadows exist. The survival of cuttings in one station indicated the success of the methodology, while the failure in other stations provided information on the possible reasons of absence/degradation of natural meadows in the area. These included the destructive impact of bottom trawling, the high pressure of grazing (the potential causes of Lessepsian migration) and the long term changes in climate resulting in alterations of environmental conditions such as increasing temperature and reduced light penetration.

Due to the randomness inherent in the occurrence of earthquakes with respect to time, space and magnitude as well as other various sources of uncertainties, seismic hazard assessment should be carried out in a probabilistic manner. Basic steps of probabilistic seismic hazard analysis are the delineation of seismic sources, assessment of the earthquake occurrence characteristics for each seismic source, selection of the appropriate ground motion attenuation relationship and identification of the site characteristics. Seismic sources can be modeled as area and line sources. Also, the seismic activity that can not be related with any major seismic sources can be treated as background source in which the seismicity is assumed to be uniform or spatially smoothed. Exponentially distributed magnitude and characteristic earthquake models are often used to describe the magnitude recurrence relationship. Poisson and renewal models are used to model the occurrence of earthquakes in the time domain. In this study, the sensitivity of seismic hazard results to the models associated with the different assumptions mentioned above is investigated. The effects of different sources of uncertainties involved in probabilistic seismic hazard analysis methodology to the results are investigated for a number of sites with different distances to a single fault. Two case studies are carried out to examine the influence of different assumptions on the final results based on real data as well as to illustrate the implementation of probabilistic seismic hazard analysis methodology for a large region (e.g. a country) and a smaller region (e.g. a province).

Σκοπός της παρούσας μελέτης είναι η χαρτογράφηση των καλλιεργειών του Νομού Αιτωλοακαρνανίας. Στη συνέχεια αφού γίνεται απολογισμός της χαρτογράφησης καθώς και περιγραφή των καλλιεργούμενων εκτάσεων για το έτος 2012 ακολουθεί ο ρόλος του μάρκετινγκ στα αγροτικά προϊόντα. Έπειτα γίνονται προτάσεις για τους παραγωγού που θέλουν να εισχωρήσουν με το παραγόμενο προϊόν τους σε μια αγορά. / The purpose of this study is to map crop Aitoloakarnania. Then after taking stock of the mapping and description of cultivated land in the year 2012 followed by the role of marketing in agricultural products. Following are recommendations for producers who want to penetrate with the product in a market.