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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Essays on insurance economics

Mantaye, Adam January 2012 (has links)
Is the relationship between insurance consumption and its determinants spurious? Is general insurance a luxury service? Do bequest motives matter for life insurance consumption? Is private credit important for the development of life insurance? Do socioeconomic development and informal risk sharing institutions matter for formal insurance consumption? This thesis investigates these and other related issues using international datasets and relatively new panel data method, namely the Common Correlated Effects Pooled (CCEP) estimator. A novelty of the CCEP is that it takes into account the impacts of unobserved common factors. The thesis consists of an introduction, three empirical chapters and conclusions. Chapter 2 studies the relationship between nonlife insurance consumption and income/wealth per capita. Estimation results suggest that income elasticity is below unity and that nonlife insurance is positively related to GDP per capita, the law, risk aversion, infrastructural development, and negatively related to socioeconomic development. Chapter 3 explores life insurance consumption driven by bequest motives. We found that life insurance consumption is positively related to GDP per capita, old age dependency ratio, infrastructural development, and social security and welfare; and negatively related to the extended family institution, savings, inflation, and risk aversion. Estimation results suggest the presence of altruistic, and bequest as exchange old age security motives. Chapter 4 investigates the long run relationship and causality direction between private credit consumption and life insurance development. Life insurance development may be explained by GDP per capita, formal and informal credit consumption, infrastructural development, life expectancy, institutional quality, inflation, and Islam, and Orthodox being the dominant religions. Cointegration test results suggest that life and nonlife insurance consumption and its determinants exhibit a long run relationship; and that there is a long run bi-directional causality relationship between life insurance development and private credit consumption. The thesis concludes that insurance development requires institutional and infrastructural development-in particular- telecommunications infrastructure, to facilitate cost effective insurance supply.
72

Il nuovo contratto a tempo determinato: IL d.lgs. 368 del 2001 interpretato alla luce della Direttiva 70 del 1999 / The New Fixed-Term Contract: The Interpretation of Legislative Decree no. 368 of 2001 According to Directive 70 of 1999

MIRANDA , NICOLA 23 February 2007 (has links)
L'interpretazione della riforma del lavoro a termine è stata oggetto di un acceso dibattito dottrinale che ha portato a conclusioni diametralmente opposte relativamente a molti punti cardine della nuova disciplina, quali: la stipula di primo contratto a termine e la necessità di esigenze di natura temporanea; le norme antifrodatorie; le norme antidiscriminatorie; le clausole di contingentamento e più in generale il ruolo del sindacato. Da una attenta analisi della riforma che parta dal contenuto della direttiva emerge che nel nostro sistema normativo esiste ancora una regola importante, ma non più scritta: i contratti a tempo indeterminato rappresentano la forma comune dei rapporti di lavoro. Da questa regola discendono una serie di considerazioni: il primo contratto a termine non è libero ma subordinato all'esistenza di ragioni oggettive che si devono intendere anche temporanee; la proroga è ammessa solo a fronte di ragioni oggettive e sopravvenute; la successione di contratti a termine è vietata quando avviene in frode alla legge; in caso di illegittima stipulazione del contratto a termine il rapporto di lavoro si deve intendere a tempo indeterminato. Quanto al ruolo del sindacato questo è stato sicuramente innovato, ma il sistema predisposto dalla riforma del lavoro a termine in molte parti ricalca la disciplina previgente contenuta nella L. 56/87 tanto che non pare corretto parlare di mortificazione del ruolo della contrattazione collettiva ma solo di riduzione dei compiti ad essa affidati. / Interpretation of the fixed term work reform has given rise to lively doctrinal debate that has led to completely opposite conclusions. Conclusions reached refer to hinge points of this new doctrine and include: the drawing up of first fixed term contracts and the necessity for temporary working requirements, anti-fraud norms, anti-discrimination norms, clauses in the fixing of quotas, and in general, the role of trade unions. Careful analysis of the reforms, starting from the content of this directive, reveals that our normative system still contains an important rule, although it is no longer written, that is: open-ended contracts still represent the most common job relationship form. Several considerations can be derived from this rule: the drawing of first fixed term contracts is not free, but subject to objective circumstances that must be proved. Mainly, the repeated extension of fixed term contracts is forbidden when it takes place against the law, and if a fixed term contract is unlawfully drawn up, then the job relationship must be intended as an open-ended one. The job of trade unions has certainly been re-emphasised due to this reform but, since the new job relationship system established by the fixed term work reform continues to enforce Law 56/87, it is not correct to talk of de-evaluation as related to collective work negotiations. Rather, trade unions will have a lesser role, and responsibilities and tasks normally charged to the trade union will be reduced.
73

Investigation Of Physical Properties Of Different Cake Formulations During Baking With Microwave And Infrared-microwave Combination

Sakiyan Demirkol, Ozge 01 January 2007 (has links) (PDF)
The main objective was to determine the variation of physical properties of different cake formulations during baking in microwave and infrared-microwave combination ovens. In the first part of the study, rheological and dielectric properties of cake batter with different formulations were determined. Different concentrations of fat and different types of emulsifier and fat replacer were used. The variation of formulation had a significant effect on the apparent viscosity of the cake batter. Cake batter was found to show shear thinning and time independent behaviour for all formulations. Dielectric properties of cake batter were dependent on formulation, frequency and temperature. In the second part of the study, physical properties (dielectric properties, volume, texture, color and porosity) of cakes baked in microwave and infrared-microwave combination oven were determined. In addition, starch gelatinization during baking was investigated. For comparison, cakes were also baked in conventional oven. Formulation and baking time were found to affect physical properties and gelatinization degree of cakes. Addition of fat to the formulation was found to increase the dielectric properties and gelatinization degree of microwave and infrared-microwave combination baked cakes. For both microwave and combination baking, cake samples with SimplesseTM had the highest volume but the firmest texture. Addition of maltodextrin resulted in a more uniform structure for infrared-microwave combination baking. There was insufficient gelatinization in microwave baked cakes ranging from 70 to 78% depending on fat content. The gelatinization degree ranged from 88 to 93% in conventionally baked cakes. Combining infrared with microwaves increased gelatinization degree (80-90%).
74

Effect Of Ultrasound On Drying Rate Of Selected Produce

Kantas, Yesim 01 April 2007 (has links) (PDF)
The objective of this study was to discover the effect of high power direct contact ultrasound on drying rates of apple, celery root, carrot and potato. For this purpose ultrasonic generator with 24 kHz frequency was used and amplitude and pulse mode values were chosen as 40%, 70%, 100%, and 0.4, 0.7, 1.0, respectively. The temperature of drying air was 30&deg / C, 40&deg / C and 50&deg / C and the velocity was kept at 3.9 m/s. The samples used were 13.5 mm in diameter with 5.0 mm thickness. It is found that ultrasound assisted drying increased the drying rate for the selected produce at all the drying conditions used the degree of which depended on the structural properties of samples. Accordingly, the most suitable drying conditions were found to be amplitude 100%, pulse mode 1.0 and 30&deg / C for celery root, amplitude 100%, pulse mode 1.0 and 30&deg / C for apple, amplitude 70%, pulse mode 1.0 and 50&deg / C for carrot and amplitude 70%, pulse mode 0.7 and 50&deg / C for potato. Data obtained were treated with respect to some mathematical models that describe the drying kinetics of samples. In this respect, Page and Modified Page models were the best to represent the drying rates in all cases. Further, the results showed that the effect of ultrasound on drying rate increased in the order of apple&gt / celery root&gt / carrot&gt / potato. That order can be attributed to the structure and composition where presence of air pockets has enhancing and sugar and starch have reducing effects.
75

Modeling Of Tempering Of Frozen Potato Puree By Microwave, Infrared Assisted Microwave And Ohmic Heating Methods

Seyhun, Nadide 01 June 2008 (has links) (PDF)
The main purpose of this thesis is to develop a model that can predict the temperature profile inside a frozen food sample during microwave tempering and infrared assisted microwave tempering processes. Another goal of the study is to compare the tempering time of frozen foods by using microwave, infrared assisted microwave, and ohmic heating methods. Frozen potato puree was used as the food sample for all studies. Three different microwave power levels (30%, 40%, and 50%) were used for microwave tempering studies. Three different microwave power levels (30%, 40%, and 50%) and three different infrared power levels (10%, 20%, and 30%) were combined for infrared assisted microwave tempering. As a control, tempering was done by keeping the sample at 4&deg / C. The increase in microwave power level and infrared power level reduced tempering time in infrared assisted microwave tempering. For the ohmic tempering studies, three different frequencies (10 kHz, 20 kHz, and 30 kHz) and three different salt contents (0.50%, 0.75%, and 1.00%) were used. The increase in frequency of ohmic heating and salt content also decreased tempering times. Microwave tempering and infrared assisted microwave tempering of frozen foods were simulated by using finite difference method. For this purpose, the change in heat capacity and the dielectric properties of frozen potato puree with respect to time were measured. The temperature distribution inside the sample was modeled, and the predicted results were compared with experimental results. The predicted temperatures showed good agreement with the experimental data (r2 &gt / 0.985). It was possible to decrease tempering times by about 75%, 90%, and 95% using ohmic, microwave, and infrared assisted microwave tempering methods, respectively as compared to control.
76

Investigation Of Quality And Staling Of Breads With Different Gum Formulations Baked In Different Ovens

Ozkoc, Semin Ozge 01 July 2008 (has links) (PDF)
The objective of this study was to determine the effects of different gums and their combination on quality and staling of breads baked in different ovens. In the first part of the study, the effects of gums (xanthan, guar, k-carrageenan, hydroxypropyl methylcellulose, locust bean gum and their blends) on quality of breads baked in infrared-microwave combination and conventional ovens were investigated. In addition, macro and micro-structure, dielectric and thermal properties and acrylamide content of breads were studied. Xanthan-guar blend addition improved bread quality with increasing specific volume and porosity values and decreasing hardness values of samples. More homogeneous closed-cell structure for conventionally baked control breads and channel formed cell structure for breads baked in infraredmicrowave combination oven were observed. Dielectric properties of breads were found to be a function of gum type. No acrylamide was formed in microwave baked breads. Breads baked in infrared-microwave combination oven had similar acrylamide content with conventionally baked ones. The second part of the study focused on staling. The hardness, retrogradation enthalpy, set back viscosity, FTIR outputs and crystallinity values of microwave-baked samples were found to be the highest. Infraredmicrowave combination heating made it possible to produce breads with similar staling degrees as conventionally baked ones and reduced the conventional baking time of breads by about 39%. Addition of xanthan-guar blend decreased hardness, retrogradation enthalpy and crystallinity values of breads. According to hardness data, in the presence of xanthan-guar blend staling of breads baked in all types of ovens was delayed for 1 day.
77

Optimization Of Roasting Conditions Of Hazelnuts In Microwave Assisted Ovens

Uysal, Nalan 01 February 2009 (has links) (PDF)
The main objective of this study was to optimize the roasting conditions of hazelnuts in microwave-infrared and microwave-convective heating combination ovens by using response surface methodology. It was also aimed to construct regression models for the prediction of quality parameters of hazelnuts as a function of processing conditions. The independent variables were microwave power (10, 30, 50, 70 and 90%), upper-lower infrared power (10, 30, 50, 70 and 90%) and roasting time (2, 3, 4, 5 and 6 min) for microwave-infrared combination roasting. Microwave power (70, 140 and 210W), air temperature (90, 150 and 210&deg / C) and roasting time (5, 15 and 25 min) were the independent variables of microwave-convective heating combination oven. As control, hazelnuts roasted in conventional oven at 150&deg / C for 20 min were used. The quality parameters were L* value, a* value, fracture force and moisture content of the hazelnuts for both microwave assisted ovens. The optimum roasting conditions of microwave-infrared combination oven were determined as 2.5 min of roasting time at 613.8W microwave power, 1800W upper infrared power, and 300W lower infrared power. Hazelnuts roasted at the optimum condition had comparable quality with the conventionally roasted ones. When micro- wave infrared combination oven was used, conventional roasting time of hazelnuts was reduced by 87.5%. Optimum roasting conditions of microwave-convective heating combination oven were 140 W microwave power, 150&deg / C air temperature and 20 min roasting time. High regression coefficients were calculated between the experimental data and predicted values showing that RSM is capable in predicting quality parameters of hazelnuts during microwave assisted roasting.
78

Usage Of Spouted Bed And Microwave Assisted Spouted Bed Dryers In Bulgur Production

Kahyaoglu, Leyla Nesrin 01 August 2009 (has links) (PDF)
The main objective of this study was to investigate the effect of spouted bed and microwave assisted spouted bed drying on drying rates and quality parameters of bulgur. The drying experiments were performed at three air temperatures (50, 70, 90oC) and at two microwave powers (288 W, 624 W). Quality parameters were selected as bulk density, apparent density, apparent porosity, internal porosity, microstructure analysis, and color for dried cooked wheat / yield and water absorption capacity for bulgur. The drying rate increased with air temperature and microwave power. Microwave assisted spouted bed drying at microwave power of 288W and 624 W reduced drying time by at least 60% and 85%, respectively compared to spouted bed drying. The effective moisture diffusivities of bulgur in the spouted bed and microwave assisted spouted bed drying were found to be 2.356x10-10 and 8.398x10-10 m2/s on the average, respectively. The effect of air temperature on product quality except color was not significant in spouted bed drying. Interior kernel porosity, sphericity and L* value of dried cooked wheat increased with air temperature and microwave power. Yield and water absorption capacity of bulgur tended to decrease as microwave power increased. According to SEM analysis, more porous structure was observed in wheat samples dried in microwave assisted spouted bed compared to air dried ones. In microwave assisted spouted bed drying, lower water absorption capacity, bulk density and apparent density, higher sphericity and lighter color were observed as compared to spouted bed drying.
79

Microwave Assisted Extraction Of Phenolic Compounds From Tomato And Sour Cherry Pomaces

Simsek, Meric 01 June 2010 (has links) (PDF)
The objective of this study was to compare microwave assisted extraction (MAE) and conventional extraction methods for the extraction of total phenolic compounds (TPC) from tomato and sour cherry pomace. Antiradical efficiency (AE) of the extracts and also the concentration of phenolic compounds were determined. In MAE, the effects of microwave power (400 and 700 W), solvent type (water, ethanol and ethanol-water mixture at 1:1 v/v), extraction time (8-20 min) and solvent to solid ratio (10, 20 and 30 ml/g) were studied to observe the change of TPC and AE of the extracts. Conventional extraction was conducted for 6 h using different solvent to solid ratios (10, 20 and 30 ml/g) and solvent types (water, ethanol and ethanol-water mixture at 1:1 v/v). When the power increased from 400 W to 700 W, TPC and AE values increased. In MAE, maximum TPC and AE values were obtained at a solvent to solid ratio of 20 ml/g. The highest TPC and AE values were obtained when the ethanol-water mixture was used for both MAE and conventional extraction. The highest TPC and AE of tomato pomace extracts was determined as 3.76 mg gallic acid equivalent, GAE/g sample and 4.84 mg 1,1-diphenyl-2-picrylhydrazyl, DPPH/g sample, respectively in MAE using power level of 700 W, ethanol-water mixture, solvent to solid ratio of 20 ml/g and extraction time of 14 min. The major phenolic acids detected in tomato pomace extract were gentisic acid and vannilic acid. For sour cherry pomace extracts, the highest TPC and AE was found as 14.14 mg GAE/g sample and 28.32 mg DPPH/g sample, respectively in MAE using power level of 700 W, solvent to solid ratio of 20 ml/g, ethanol-water mixture and extraction time of 12 min. Epicatechin was found to be the major phenolic acid in sour cherry pomace. There was no significant difference in different extraction methods in terms of TPC. On the other hand, AE value and concentration of major phenolic acids of tomato and sour cherry pomace increased when MAE was used.
80

Detection Of Gamma Irradiated Spices With Osl Method And Its Reliability

Aygun, Sukran Gizem 01 September 2010 (has links) (PDF)
The aim of this current work is to analyze the behavior of OSL (Optically Stimulated Luminescence) signals of irradiated spices with respect to time, temperature, origin and the type. Throughout the experiments, 3 different type spices from four different origins were stored at 4&deg / C and 25&deg / C for six months after irradiation. During experiments, unirradiated red pepper, thyme and cumin samples were analyzed by using OSL technique in order to determine the background OSL signal values of samples. Samples were irradiated 10 kGy by Cobalt 60 gamma source in TAEK (Turkey Atomic Energy Association). After irradiation process, OSL signal values of different samples were analyzed according to the given parameters. In order to determine the effect of temperature on OSL signal loss, temperature (4&deg / C- 25&deg / C) was set as storage temperature. The analyses were made monthly. According to the statistical analyses (ANOVA- General Linear Model), origin and type of samples were detected as significant parameters of design experiment. Time and temperature effect on OSL signal loss changed with respect to origin and type of samples. After six months storage period, OSL signal was lost for most of the origin and sample type. At the end of sixth month, an ESR analysis was performed to detect the accuracy of the OSL technique. With respect to the results of these experiments, it was seen that, due to optical fading, most of the samples was observed as unirradiated by OSL technique, however ESR analyze the samples as irradiated at the end of sixth month. Irradiation had a detrimental effect on the microbiological load of the samples and resulted 6 log reduction on the microbial population. After irradiation, no colony formation was observed in total bacteria and yeast- mold count. During six month period, no injury recovery was observed.

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