Much attention in recent years has gone to the evaluation of teacher effectiveness, and some scholars have developed conceptual models to evaluate the effectiveness. The purpose of this study was to compare three teacher evaluation models – the Texas Professional Development Appraisal System (PDAS), the teacher index model (TI), and the value-added model (VAM) – to determine teacher effectiveness using student demographic and longitudinal academic data. Predictive data from students included economic disadvantage status, ethnicity, gender, participation in special education, limited English proficiency, and performance on Texas Assessment of Knowledge and Skills (TAKS). Data serving as dependent variables were scores from Scholastic Aptitude Test (SAT®) verbal/critical reasoning and mathematics. These data came from 1,714 students who were 9.7% Hispanic, 9.2% African American, and 81.2% White. The models were tested for 64 English language arts teachers and 109 mathematics teachers, using student examination scores from the SAT® verbal/critical reasoning and mathematics. The data were aligned for specific faculty members and the students whom they taught during the year of the study. The results of the study indicated that the TI and VAM explained approximately 42% of the variance in college entrance exam scores from the SAT® verbal/critical reasoning and mathematics (R2 = 0.418) across mathematics and English language arts teachers, whereas the TI model explained approximately 40% of the variance in the SAT® scores (R2 = 0.402). The difference, however, in the R-squared values between the VAM and the TI model was not statistically significant (t (169) = 1.84, p > 0.05), suggesting that both models provided similar results. The least effective model used to predict student success on college entrance exams was the PDAS, which is a state-adopted model currently in use in over 1,000 school districts in Texas, The teacher PDAS scores explained approximately 36% of the variance in student success on the SAT® (R2 = 0.359). The study provides school leadership with information about alternative methods of evaluating teacher effectiveness without difficult formulas or high costs associated with hiring statisticians. In addition, results indicate that the models vary significantly in the extent to which they can predict which teachers are most effective in preparing students for college. This study also emphasizes the critical need to provide teacher evaluations that align with student achievement on college entrance exams.

In today's digital world, information and communication technology accounts for 3% and 2% of the global power consumption and CO2 emissions respectively. This alarming figure is on an upward trend, as future telecommunications systems and handsets will become even more power hungry since new services with higher bandwidth requirements emerge as part of the so called ¿future internet¿ paradigm. In addition, the mobile handset industry is tightly coupled to the consumer need for more sophisticated handsets with greater battery lifetime. If we cannot make any significant step to reducing the energy gap between the power hungry requirements of future handsets, and what battery technology can deliver, then market penetration for 4G handsets can be at risk. Therefore, energy conservation must be a design objective at the forefront of any system design from the network layer, to the physical and the microelectronic counterparts. In fact, the energy distribution of a handset device is dominated by the energy consumption of the RF hardware, and in particular the power amplifier design. Power amplifier design is a traditional topic that addresses the design challenge of how to obtain a trade-off between linearity and efficiency in order to avoid the introduction of signal distortion, whilst making best use of the available power resources for amplification. However, the present work goes beyond this by investigating a new line of amplifiers that address the green initiatives, namely green power amplifiers. This research work explores how to use the Doherty technique to promote efficiency enhancement and thus energy saving. Five different topologies of RF power amplifiers have been designed with custom-made signal splitters. The design core of the Doherty technique is based on the combination of a class B, class AB and a class C power amplifier working in synergy; which includes 90-degree 2-way power splitter at the input, quarter wavelength transformer at the output, and a new output power combiner. The frequency range for the amplifiers was designed to operate in the 3.4 - 3.6 GHz frequency band of Europe mobile WiMAX. The experimental results show that 30dBm output power can be achieved with 67% power added efficiency (PAE) for the user terminal, and 45dBm with 66% power added efficiency (PAE) for base stations which marks a 14% and 11% respective improvement over current stateof- the-art, while meeting the power output requirements for mobile WiMAX applications.

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Detta examensarbete syftar till att undersöka och analysera miljöcertifieringarnas påverkan på den svenska bostadsmarknaden. Fokus ligger på tre huvudsakliga miljöcertifieringssystem: BREEAM, LEED och Miljöbyggnad. Studien avser att identifiera om och hur dessa certifieringar kan skapa ett ekonomiskt mervärde för fastigheter, med särskild uppmärksamhet på hur dessa värden uppfattas och värderas av fastighetsägare. Examensarbetet har som mål att analysera hur miljöcertifieringar påverkar fastighetsvärden på den svenska bostadsmarknaden och undersöka om certifieringarna leder till mervärde eller eventuella konkurrensfördelar på bostadsmarknaden. En kvalitativ metod används, där semi-strukturerade intervjuer med nyckelpersoner inom fastighetsbranschen utgör den primära datainsamlingen. Urvalet av respondenter baseras på deras erfarenheter och insikter i utvecklingen och förvaltningen av hållbara bostäder. Den teoretiska ramen inkluderar värdeteori och en detaljerad genomgång av de valda miljöcertifieringssystemen. Studien visar att miljöcertifieringar kan erbjuda flera konkurrensfördelar för fastighetsutvecklare och förvaltare. Miljöcertifierade byggnader tenderar att ha högre hyres- och försäljningspriser samt lägre driftkostnader tack vare minskad energiförbrukning och vattenanvändning. Resultaten indikerar dock att värdet av miljöcertifieringar varierar beroende på marknadssegment och kundernas miljömedvetenhet. Utmaningar inkluderar höga kostnader för certifieringsprocessen och osäkerheter kring de ekonomiska fördelarna, vilket kräver noggrann avvägning från fastighetsägarnas sida. Studien bidrar till en fördjupad förståelse av hur miljöcertifieringar kan påverka bostadsmarknaden och ger värdefulla insikter för fastighetsutvecklare och förvaltare i deras framtida beslut om hållbarhetsinvesteringar. / This thesis aims to investigate and analyze the impact of environmental certifications on the Swedish housing market. The focus is on three main environmental certification systems: BREEAM, LEED, and Miljöbyggnad. The study seeks to identify whether and how these certifications can create economic value for properties, with particular attention to how these values are perceived and evaluated by property owners. The aim of this thesis is to analyze how environmental certifications affect property values in the Swedish housing market and to investigate whether the certifications lead to added value or potential competitive advantages in the housing market. A qualitative method is employed, with semi-structured interviews with key stakeholders in the real estate industry serving as the primary data collection method. Respondents were selected based on their experiences and insights into the development and management of sustainable housing. The theoretical framework includes value theory and a detailed review of the selected environmental certification systems. The study shows that environmental certifications can offer several competitive advantages for real estate developers and managers. Certified buildings tend to have higher rental and sales prices and lower operating costs due to reduced energy and water consumption. However, the results indicate that the value of environmental certifications varies depending on market segment and customer environmental awareness. Challenges include high certification process costs and uncertainties about economic benefits, requiring careful consideration by property owners. The study contributes to a deeper understanding of how environmental certifications can impact the housing market and provides valuable insights for real estate developers and managers in their future sustainability investment decisions.

The prevalence of antibiotics on farms for therapeutic and prophylactic use in animals can cause negative effects on biomethane production during anaerobic digestion. Previous literature has found decreased biomethane production rates from a variety of antibiotics, but biogas inhibition differs between studies of continuous and batch reactors and the type of antibiotic studied. Cephalosporin drugs are the most common antibiotic class used to treat mastitis in dairy cows and can retain most of their bioactivity after excretion. Ceftiofur is a commonly used cephalosporin drug but no previous study investigating the effect of Ceftiofur on biomethane during continuous anaerobic digestion has been performed. The aim of this study was to examine the effect on biomethane production when manure from cows treated with Ceftiofur was anaerobically digested. Laboratory sized anaerobic digesters (AD) were run at thermophilic (55°C) temperatures and a 10 day hydraulic retention time. Manure from cows treated with Ceftiofur were fed to the antibiotic treatment reactors for 50 days. The reactor performance was measured by i) biomethane production, ii) waste stabilization in terms of solids and chemical oxygen demand, iii) change in mass of Ceftiofur and iv) change in concentration of antibiotic resistant genes, specifically cfx(A), mef(A), and tet(Q). There was statistically significant decrease in cumulative gas production due to the addition of Ceftiofur into the reactors, but no significant difference between treatments in waste stabilization in terms of percent volatile solids (VS) and total chemical oxygen demand (TCOD) reduction. Anaerobic digestion decreased the amount of Ceftiofur in manure, and the amount of Ceftiofur in the reactors reduced over the time of the experiment. Change in antibiotic resistant genes (ARGs) were gene dependent over time. Concentrations of tet(Q) reduced significantly between feed and effluent of both treatments, and cfx(A) reduced significantly for the control treatment but not the Ceftiofur treatment. Concentrations of mef(A) increased over time in both treatments. Overall, the addition of Ceftiofur in continuously operated anaerobic digesters negatively affected biomethane production, a value-added product responsible for on-farm renewable energy. However, anaerobic digestion does decrease the mass of Ceftiofur within manure, thereby reducing the environmental loading from run-off from farms. / Master of Science / Anaerobic digestion is a biological treatment technology used on farms to treat manure. It can be used to reduce potential environmental damage from contaminants and manure, homogenize manure for fertilizer, and produce methane gas for renewable energy. An emerging challenge in manure management is the presence of antibiotics such as ceftiofur used in animal production to prevent and treat illnesses. When antibiotics are used on livestock, they are excreted from the animal in manure. When the manure is added to the digester, the antibiotic molecules within the manure can kill the bacteria responsible for manure homogenization and gas production. Ceftiofur is a type of cephalosporin antibiotic used to treat dairy cows for mastitis, a bacterial infection of the udder. When the cows are treated with Ceftiofur, it can remain in the excreted manure and enter the digester. The use of antibiotics on farms is also leading to a global phenomenon known as antibiotic resistance. The bacteria that are exposed to antibiotics can develop mutations to become immune to the antibiotic, and can spread the mutations through antibiotic resistant genes (ARGs). ARGs can spread to bacteria which have never been exposed to antibiotics, making them resistant. This causes a significant concern in regards to disease treatment across the world as the efficacy of antibiotics is threatened. Understanding how ARGs move and how they can be eliminated is crucial to preventing global antibiotic resistance. The purpose of this study was to assess the effect of anaerobic digestion on Ceftiofur and ARGs. Four continuous lab-scale anaerobic digesters, two using control manure and two using manure from cows treated with Ceftiofur, were run at 55˚C for a period of 50 days. Over time, the reactor with manure from cows treated with the Ceftiofur antibiotic produced less gas as compared to the control digesters. The amount of Ceftiofur within the digesters decreased over time, demonstrating anaerobic digestion’s ability to degrade the antibiotic molecule. The effect of anaerobic digestion on the ARG concentration was gene specific. The concentration of the tet(Q) gene, a gene responsible for resistance against the very common antibiotic tetracycline, was reduced by anaerobic digestion. These results demonstrate that anaerobic digestion is a technology which can reduce the environmental impact of manure from Ceftiofur-treated cows. This shows that manure treatment can be a first step in combating antibiotic resistance across the globe.

his dissertation advocates that value and its creation are often misunderstood concepts since both lack robust comprehensive conceptual foundations from which to advance rigorous theoretical development and analysis. Furthermore, this dissertation characterized value as the subjective assessment of the total worth of benefits received for the price paid or costs, i.e. money, time, energy, etc. The purpose of this dissertation was to conduct a holistic examination of value through the lens of service-dominant logic (S-D) and several historical economic periods of thought. I conducted a comprehensive S-D literature review in conjunction with a conceptual Boardman Soft Systems Methodology to develop a systemigram that captured the most critical S-D concepts and interrelationships to clarify its purpose and future research opportunities. During this process, value was recategorized and simplified into five primary dimensions, i.e. nature, perspectives, measures, storage, and creation. I employed Maslow's hierarchy of needs theory to illustrate that value at the lowest level of abstraction is the efficient satisfaction of human needs. I also investigated value creation and introduced a comprehensive value creation conceptual framework. Value creation is seen as a continuum of activity of key processes, i.e. value co-production, value in exchange, and value co-creation, and key procedural elements, i.e. actors, resource integration, ecosystems, services exchange, institutions and institutional arrangements as essentials to value creation. In addition, this dissertation also presented a Leyden value concept to the S-D lexicon. This concept complements use-value to capture associate upstream co-production activities and efforts as stored potential value. This dissertation then employed this conceptual framework to perform two survey based empirical studies. The first tested Lusch et al. (2007) value-co-production framework and incorporated other constructs such as transaction cost, satisfaction, and future purchase intent into a single testable model. This study leveraged covariance based structural equation modeling with 477 respondents to simultaneously test the proposed model and advance Self Determination Theory and Transaction Cost Economics within the realm of value creation and S-D Logic. This research found that most of Lusch et al. (2007) hypotheses were supported and found statistical support for the inclusion of transaction cost as a construct that influences value-co-production. In addition, this study illustrated that value-co-production has a positive statistical association with satisfaction and its impact on consumer future purchase intent. Managerial, this study highlighted those customer characteristics and behaviors necessary to maximize value generation during co-production opportunities. Finally, this dissertation empirically investigated the importance of benefits and equivalent cost reductions to entice consumer purchase intention across two different products and services scenarios. In total, this research gathered over 2,500 observations through a series of eight between subject survey experiments. This research found that consumers choose benefits such as warranty enhancements for new vehicle purchases and complementary desserts for dining experiences to enhance purchase intention. In addition, this research often revealed that consumers significantly decrease purchase intention when offered small value enhancements, i.e. 1% price reductions. This research also discovered that narcissism is negatively associated with those consumers who chose a donation to social causes. Finally, enhanced value offerings for expensive vacations, either through benefit enhancements or cost reductions, fail to significantly impact consumer purchase intention. The results of this research advance rational choice theory into the realm of value creation and S-D. Managerially, this research found that benefits, whether singular or offered as a menu, are powerful tools for retailers to employ to enhance consumer purchase intention.

Technological advances have had a major impact on traditional retail shopping changing it from a physical undertaking to a completely digitised experience where consumers buy digital media online. VAT systems that do not specifically provide for, or which have not been adapted to cope with, technology-driven advances, generally do not provide for the adequate levying and collection of VAT on cross-border digital trade. The South African VAT system is no different. The taxation of e-commerce should not artificially advantage or disadvantage e-commerce over comparable traditional commerce, or unnecessarily hinder the development of e-commerce. This thesis determines whether the South African VAT Act 89 of 1991 in its current form, can be applied adequately to raise and collect VAT on cross-border digital transactions. Where shortcomings in the VAT Act are identified, the harmonised VAT rules of the European Union (EU), together with the Organisation for Economic Cooperation and Development (OECD) proposals on consumption taxes, are analysed and discussed to seek possible solutions and make recommendations. / Mercantile Law / LL.D.

Technological advances have had a major impact on traditional retail shopping changing it from a physical undertaking to a completely digitised experience where consumers buy digital media online. VAT systems that do not specifically provide for, or which have not been adapted to cope with, technology-driven advances, generally do not provide for the adequate levying and collection of VAT on cross-border digital trade. The South African VAT system is no different. The taxation of e-commerce should not artificially advantage or disadvantage e-commerce over comparable traditional commerce, or unnecessarily hinder the development of e-commerce. This thesis determines whether the South African VAT Act 89 of 1991 in its current form, can be applied adequately to raise and collect VAT on cross-border digital transactions. Where shortcomings in the VAT Act are identified, the harmonised VAT rules of the European Union (EU), together with the Organisation for Economic Cooperation and Development (OECD) proposals on consumption taxes, are analysed and discussed to seek possible solutions and make recommendations. / Mercantile Law / LL.D.

Master of Science / Department of Agricultural Economics / Ted C. Schroeder / Value-added management at the cow-calf level is integrated across breeding, health and nutrition programs. Hedonic pricing models are necessary to navigate through the layered management standards imposed by certified health and marketing programs on the cow-calf sector. Previous research in feeder calf pricing models provides insight on the use and development of ordinary least squares in estimating price effects. Breed, vaccination program, age-and-source verification and natural-beef production have become more relevant as vertical coordination has influenced commercial cow-calf producers. This study provides the industry with new information pertaining to the revenue opportunities that exist for cow-calf producers through increased coordination in the beef industry. Video and satellite auction markets are recognized as a national pricing mechanism for feeder cattle in the United States. These markets represent the management and marketing practices of national cow-calf producers and the tastes and preferences of a national stocker and feedlot industry. Previous research in feeder cattle pricing models is applied to the current genetic, management, marketing and market structure information from video auction markets to discover relevant price effects pertaining to value-added calf production. More intensive value-added management practices were expected to enhance the revenue of cow-calf producers selling their calves through video auction markets. This research confirms that verified health and genetic claims produce higher calf prices compared to commodity calves. Weaned calves with at least two rounds of respiratory vaccinations generated an additional $5.50 to $7.50 per cwt., and weaning created $2.75 to $4.50 per cwt. in premiums over non-certified health programs. There were statistical differences among the premiums for each aggregated breed influence, and Angus and black and black-white faced cattle offered the highest breed premiums at $5.25 to $7.50 per cwt. compared to Brahman-influenced calves. Age-and-source verification presents the best opportunity for video auction market premiums among recently developed marketing programs. Statistically significant premiums ranged from $1.25 to $2.00 per cwt. for both steers and heifers over the last five years.

Estate massing is one of the estate planning instruments used by estate planners, especially with regards to marriages in community of property; nonetheless any two people (or more) may mass their whole estates or a part thereof. Section 37 of the Administration of Estates Act describes massed estates and therefore it also supplies the requirements for estate massing and will be explored in this study. Estate massing gives rise to tax consequences that would not have arised normally. Due to estate massing there will be tax consequences for the predeceased testator and the surviving testator(s) and even in some cases there will be tax consequences for the heirs. In this study, attention is paid to the tax consequences of estate duty, donations tax, transfer duty, VAT and CGT. The purpose of this study is to determine the difference between the consequences of estate massing should it happen in accordance with the requirements of the Administration of Estates Act and should it not happen in accordance with the requirements of the Administration of Estates Act. / LLM (Estate Law), North-West University, Potchefstroom Campus, 2013