Search results for: multi-level resistive switching

Authors: Melvin Sethobya, Sithule Xanga, Sechaba Lenong, Lunga Nolakana, Gbenga Adesola

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Mining has been the cornerstone of the South African economy for the last century. Most of the gold mining in South Africa was conducted within the Witwatersrand basin, which contributed to the rapid growth of the city of Johannesburg and capitulated the city to becoming the business and wealth capital of the country. But with gradual depletion of resources, a stoppage in the extraction of underground water from mines and other factors relating to survival of the mining operations over a lengthy period, most of the mines were abandoned and left to pollute the local waterways and groundwater with toxins, heavy metal residue and increased acid mine drainage ensued. The Department of Mineral Resources and Energy commissioned a project whose aim is to monitor, maintain, and mitigate the adverse environmental impacts of polluted water mine water flowing into local streams affecting local ecosystems and livelihoods downstream. As part of mitigation efforts, the diagnosis and monitoring of groundwater or surface water polluted sites has become important. Geophysical surveys, in particular, Resistivity and Magnetics surveys, were selected as some of most suitable techniques for investigation of local ingress points along of one the major streams cutting through the Witwatersrand basin, namely the Blesbokspruit, which is found in the eastern part of the basin. The aim of the surveys was to provide information that could be used to assist in determining possible water loss/ ingress from the Blesbokspriut stream. Modelling of geophysical surveys results offered an in-depth insight into the interaction and pathways of polluted water through mapping of possible ingress channels near the Blesbokspruit. The resistivity - depth profile of the surveyed site exhibit a three(3) layered model with low resistivity values (10 to 200 Ω.m) overburden, which is underlain by a moderate resistivity weathered layer (>300 Ω.m), which sits on a more resistive crystalline bedrock (>500 Ω.m). Two locations of potential ingress channels were mapped across the two traverses at the site. The magnetic survey conducted at the site mapped a major NE-SW trending regional linearment with a strong magnetic signature, which was modeled to depth beyond 100m, with the potential to act as a conduit for dispersion of stream water away from the stream, as it shared a similar orientation with the potential ingress channels as mapped using the resistivity method.

Keywords: eletrictrical resistivity, magnetics survey, blesbokspruit, ingress

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Authors: G. E. Kiral, O. Elma, A. T. Ince, B. Vural, U. S. Selamogullari, M. Uzunoglu

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Energy is an indispensable resource to meet the needs of people. Depending on the needs of people, the correct and efficient use of electrical energy has became important nowadays. Besides the need for the electrical energy is also increasing with the rapidly developing technology and continuously changing living standards. Due to the depletion of energy sources and increased demand for electricity, efficient energy use is an important research topic. Recently, ideas like smart cities, smart buildings and smart homes have been widely used under smart grid concept. With smart grid infrastructure, it will be possible to monitor electrical demand of a residential customer and control each electricity generation center for more efficient energy flow. The smallest component of the smart grid can be considered as smart homes. Better utilization of the electrical grid can be achieved through the communication of the smart home with both other customers in the grid and appliances in the house itself since generation can effectively be scheduled by having more precise demand data. Smart Plugs are used for the communication with the household appliances in the house. Smart Plug is an intermediate control element, which can be mounted on the existing outlet, and thus can be used to monitor the energy consumption of the plugged device and also can provide on/off control energy remotely. This study proposes a Smart Plug for energy monitoring and energy management. Proposed design is composed of five subsystems: micro controller embedded system with communication system, metering circuitry, power supply and switching circuitry. The developed smart plug offers efficient use of electrical energy.

Keywords: energy efficiency, home energy management, smart home, smart plug

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Authors: A. Sreedevi, G. Anantaramu

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The present space research organizations are striving towards the development of lighter, smaller, more efficient, low cost, and highly reliable power supply. Switch mode power supplies (SMPS) overcome the demerits of linear power supplies such as low efficiency, difficulties in thermal management, and in boosting the output voltage. Space applications require a constant DC voltage to supply its load. As the load varies, the battery terminal voltage tends to vary accordingly. To avoid this variation in the load terminal voltage, a DC-DC regulator is required. The conventional regulator for space applications is isolated boost topology. The proposed topology uses an interleaved push-pull converter with a current doubler secondary to reduce the EMI issues and increase efficiency. The proposed topology uses a floating technique where the converter derives power from the battery and generates only the voltage that is required to fill the gap between the bus and the battery voltage. The direct voltage sense and current loop provide tight regulation of output and better stability. Converter is designed with 50 kHz switching frequency using UC 1825 PWM controller employing both voltage and peak current mode control. Experimental tests have been carried out on the converter under different input and load conditions to validate the design. The experimental results showed that the efficiency was greater than 91%. Stability analysis is done using venable stability analyzer.

Keywords: push pull converter, current doubler, converter, PWM control

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Authors: Jack R. McKenzie, Peter A. Appleby, Thomas House, Neil Walton

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Cold-start is a notoriously difficult problem which can occur in recommendation systems, and arises when there is insufficient information to draw inferences for users or items. To address this challenge, a contextual bandit algorithm – the Fast Approximate Bayesian Contextual Cold Start Learning algorithm (FAB-COST) – is proposed, which is designed to provide improved accuracy compared to the traditionally used Laplace approximation in the logistic contextual bandit, while controlling both algorithmic complexity and computational cost. To this end, FAB-COST uses a combination of two moment projection variational methods: Expectation Propagation (EP), which performs well at the cold start, but becomes slow as the amount of data increases; and Assumed Density Filtering (ADF), which has slower growth of computational cost with data size but requires more data to obtain an acceptable level of accuracy. By switching from EP to ADF when the dataset becomes large, it is able to exploit their complementary strengths. The empirical justification for FAB-COST is presented, and systematically compared to other approaches on simulated data. In a benchmark against the Laplace approximation on real data consisting of over 670, 000 impressions from autotrader.co.uk, FAB-COST demonstrates at one point increase of over 16% in user clicks. On the basis of these results, it is argued that FAB-COST is likely to be an attractive approach to cold-start recommendation systems in a variety of contexts.

Keywords: cold-start learning, expectation propagation, multi-armed bandits, Thompson Sampling, variational inference

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Authors: Sudarshan Chalise, Athula Naranpanawa

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This paper attempts to investigate the viability of cropland re-allocation as an adaptation strategy to minimise the economy-wide costs of climate change on agriculture. Nepal makes an interesting case study as it is one of the most vulnerable agricultural economies within South Asia. This paper develops a comparative static multi-household Computable General Equilibrium (CGE) model for Nepal with a nested set of Constant Elasticity of Transformation (CET) functional forms to model the allocation of land within different agricultural sectors. Land transformation elasticities in these CET functions are allowed to reflect the ease of switching from one crop to another based on their agronomic characteristics. The results suggest that, in the long run, farmers in Nepal tend to allocate land to crops that are comparatively less impacted by climate change, such as paddy, thereby minimizing the economy-wide impacts of climate change. Furthermore, the results reveal that land re-allocation tends to reduce the income disparity among different household groups by significantly moderating the income losses of rural marginal farmers. Therefore, it is suggested that policy makers in Nepal should prioritise schemes such as providing climate-smart paddy varieties (i.e., those that are resistant to heat, drought and floods) to farmers, subsidising fertilizers, improving agronomic practices, and educating farmers to switch from crops that are highly impacted by climate change to those that are not, such as paddy.

Keywords: climate change, general equilibrium, land re-allocation, nepalese agriculture

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Authors: Naheem Olakunle Adesina

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The memristor is considered as one of the promising candidates for mamoelectronic engineering and applications. Owing to its high compatibility with CMOS, nanoscale size, and low power consumption, memristor has been employed in the design of commonly used circuits such as phase-locked loop (PLL). In this paper, we designed a memristor-based loop filter (LF) together with other components of PLL. Following this, we evaluated the noise-rejection feature of loop filter by comparing the noise levels of input and output signals of the filter. Our SPICE simulation results showed that memristor behaves like a linear resistor at high frequencies. The result also showed that loop filter blocks the high-frequency components from phase frequency detector so as to provide a stable control voltage to the voltage controlled oscillator (VCO). In addition, we examined the effects of temperature on the performance of the designed phase locked loop circuit. A critical temperature, where there is frequency drift of VCO as a result of variations in control voltage, is identified. In conclusion, the memristor is a suitable choice for nanoelectronic systems owing to a small area, low power consumption, dense nature, high switching speed, and endurance. The proposed memristor-based loop filter, together with other components of the phase locked loop, can be designed using memristive emulator and EDA tools in current CMOS technology and simulated.

Keywords: Fast Fourier Transform, hysteresis curve, loop filter, memristor, noise, phase locked loop, voltage controlled oscillator

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Authors: Carin Lindskog

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Introduction: Long-term success requires an organizational balance between continuity (exploitation) and change (exploration). The problem of balancing exploitation and exploration is a common issue in studies of organizational learning. In order to better face the tough competition in the face of changes, organizations need to exploit their current business and explore new business fields by developing new capabilities. The purpose of this work in progress is to develop a conceptual framework to shed light on the relevance of 'learning activities', i.e., exploitation and exploration, on different levels. The research questions that will be addressed are as follows: What sort of learning activities are found in the Business Process Management (BPM) field? How can these activities be linked to the individual level, group, level, and organizational level? In the work, a literature review will first be conducted. This review will explore the status of learning activities in the BPM field. An outcome from the literature review will be a conceptual framework of learning activities based on the included publications. The learning activities will be categorized to focus on the categories exploitation, exploration or both and into the levels of individual, group, and organization. The proposed conceptual framework will be a valuable tool for analyzing the research field as well as identification of future research directions. Related Work: BPM has increased in popularity as a way of working to strengthen the quality of the work and meet the demands of efficiency. Due to the increase in BPM popularity, more and more organizations reporting on BPM failure. One reason for this is the lack of knowledge about the extended scope of BPM to other business contexts that include, for example, more creative business fields. Yet another reason for the failures are the fact of the employees’ are resistant to changes. The learning process in an organization is an ongoing cycle of reflection and action and is a process that can be initiated, developed and practiced. Furthermore, organizational learning is multilevel; therefore the theory of organizational learning needs to consider the individual, the group, and the organization level. Learning happens over time and across levels, but it also creates a tension between incorporating new learning (feed-forward) and exploiting or using what has already been learned (feedback). Through feed-forward processes, new ideas and actions move from the individual to the group to the organization level. At the same time, what has already been learned feeds back from the organization to a group to an individual and has an impact on how people act and think.

Keywords: business process management, exploitation, exploration, learning activities

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Authors: Keshavamurthy Ganapathy Bhat, Manvinderpal Singh Marwaha

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Background: Coronary artery Disease (CAD) is a common cause of morbidity, mortality and reason for unfitness amongst aircrew. Coronary angioplasty and stenting are the standard of care for CAD. Antiplatelet drugs like Aspirin and Clopidogrel(Dual Antiplatelet therapy) are routinely prescribed post-stenting which are permitted for flying. However, in the recent past, Ticagrelor is being used in place of Clopidogrel as per ACC AHA and ESC guidelines. However Ticagrelor is not permitted for flying. Case Presentation: A 55-year-old pilot suffered Anterior Wall Myocardial Infarction. Angiography showed blockages in Left Anterior Descending Artery(LAD) and Right coronary artery (RCA). He underwent primary angioplasty and stenting LAD and subsequent stenting to RCA. Recovery was uneventful. One year later he was asymptomatic with normal Left ventricular function and no reversible perfusion defect on stress MPI. He had patent stents and coronaries on check angiogram. However, he was not allowed to fly since he was on Ticagrelor. He had to be switched over to Clopidogrel from Ticagrelor one year after stenting to permit him for flying. Similarly, switching had to be done in a 45-year-old pilot. Ticagrelor has been proven to be more effective than clopidogrel and as safe as Clopidogrel in preventing stent thrombosis. If Clopidogrel is being permitted, there is no need to restrict Ticagrelor. Hence "Policy" needs to be changed. Conclusions: Dual Antiplatelet therapy is the standard of care post coronary stenting which has been proved safe and effective. Policy needs to be changed to permit flying with Ticagrelor which is more effective than Clopidogrel and equally safe.

Keywords: antiplatelet drugs, coronary artery disease, stenting, ticagrelor

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Authors: Niloofar Fariborzi, Hamzeh Alipour, Kourosh Azizi, Neda Eskandarzade, Abozar Ghorbani

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The family Parvoviridae consists of a large diversity of single-stranded DNA viruses, which cause mild to severe diseases in both vertebrates and invertebrates. The Parvoviridae are classified into three subfamilies: Parvovirinae infect vertebrates, Densovirinae infects invertebrates, while Hamaparovirinae infects both vertebrates and invertebrates. Except for the NS1 region, which is the prime criterion for phylogeny analysis, other parts of the parvoviruses genome, such as UTRs, are diverse even among closely related viruses or within the same genus. It is believed that host switching in parvoviruses may be related to genetic changes in regions other than NS1; therefore, whole-genome screening is valuable for studying parvoviruses' host-virus interactions. The aim of this study was to analyze genome organization and phylogeny of the complete genome sequence of the 132 Paroviridae family members, focusing on viruses that infect invertebrates. The maximum and minimum divergence within each subfamily belonged to Densovirinae and Parvovirinae, respectively. The greatest evolutionary divergence was between Hamaparovirinae and Parvovirinae. Unclassified viruses were mostly from Parovirinae and had the highest divergence to densoviruses and the lowest divergence to Parovirinae viruses. In a phylogenetic tree, all hamparoviruses were found in the center of densoviruses, with the exception of Syngnathid Ichthamaparvovirus 1 (NC_055527), which was positioned between two Parvovirinae members (NC _022089 and NC_038544). The proximity of hamparoviruses members to some densoviruses strengthens the possibility that densoviruses may be the ancestors of hamaparoviruses or vice versa. Therefore, examination and phylogeny analysis of the whole genome is necessary to understand Parvoviridae family host selection.

Keywords: densoviruses, parvoviridae, bioinformatics, phylogeny

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Authors: Nalla Somaiah, Praveen Kumar

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Scaling of transistors and, hence, interconnects is very important for the enhanced performance of microelectronic devices. Scaling of devices creates significant complexity, especially in the multilevel interconnect architectures, wherein current crowding occurs at the corners of interconnects. Such a current crowding creates hot-spots at the respective corners, resulting in non-uniform temperature distribution in the interconnect as well. This non-uniform temperature distribution, which is exuberated with continued scaling of devices, creates a temperature gradient in the interconnect. In particular, the increased current density at corners and the associated temperature rise due to Joule heating accelerate the electromigration induced failures in interconnects, especially at corners. This has been the classic reliability issue associated with metallic interconnects. Herein, it is generally understood that electromigration induced damages can be avoided if the length of interconnect is smaller than a critical length, often termed as Blech length. Interestingly, the effect of non-negligible temperature gradients generated at these corners in terms of thermomigration and electromigration-thermomigration coupling has not attracted enough attention. Accordingly, in this work, the interplay between the electromigration and temperature gradient induced mass transport was studied using standard Blech structure. In this particular sample structure, the majority of the current is forcefully directed into the low resistivity metallic film from a high resistivity underlayer film, resulting in current crowding at the edges of the metallic film. In this study, 150 nm thick Cu metallic film was deposited on 30 nm thick W underlayer film in the configuration of Blech structure. Series of Cu thin strips, with lengths of 10, 20, 50, 100, 150 and 200 μm, were fabricated. Current density of ≈ 4 × 1010 A/m² was passed through Cu and W films at a temperature of 250ºC. Herein, along with expected forward migration of Cu atoms from the cathode to the anode at the cathode end of the Cu film, backward migration from the anode towards the center of Cu film was also observed. Interestingly, smaller length samples consistently showed enhanced migration at the cathode end, thus indicating the existence of inverse Blech length effect in presence of temperature gradient. A finite element based model showing the interplay between electromigration and thermomigration driving forces has been developed to explain this observation.

Keywords: Blech structure, electromigration, temperature gradient, thin films

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Authors: Jessevel Montes

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This study explored on the culture of journal writing among the Senior High School Manobo students. The purpose of this qualitative morpho-semantic and syntactic study was to discover the morphological, semantic, and syntactic features of the written output through morphological, semantic, and syntactic categories present in their journal writings. Also, beliefs and practices embedded in the norms, values, and ideologies were identified. The study was conducted among the Manobo students in the Senior High Schools of Central Mindanao, particularly in the Division of North Cotabato. Findings revealed that morphologically, the features that flourished are the following: subject-verb concordance, tenses, pronouns, prepositions, articles, and the use of adjectives. Semantically, the features are the following: word choice, idiomatic expression, borrowing, and vernacular. Syntactically, the features are the types of sentences according to structure and function; and the dominance of code switching and run-on sentences. Lastly, as to the beliefs and practices embedded in the norms, values, and ideologies of their journal writing, the major themes are: valuing education, family, and friends as treasure, preservation of culture, and emancipation from the bondage of poverty. This study has shed light on the writing capabilities and weaknesses of the Manobo students when it comes to English language. Further, such an insight into language learning problems is useful to teachers because it provides information on common trouble-spots in language learning, which can be used in the preparation of effective teaching materials.

Keywords: applied linguistics, culture, morpho-semantic and syntactic analysis, Manobo Senior High School, Philippines

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Authors: Sylvain Perrin, Thomas Saillour

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The Grande-Motte port and seafront development project on the French Mediterranean coastline entailed evaluating wave impact loads (pressures and forces) on the new beach seawall and comparing the resulting scour potential at the base of the existing and new seawall. A physical model was built at ARTELIA’s hydraulics laboratory in Grenoble (France) to provide insight into the evolution of scouring overtime at the front of the wall, quasi-static and impulsive wave force intensity and distribution on the wall, and water and sand overtopping discharges over the wall. The beach was constituted of fine sand and approximately 50 m wide above mean sea level (MSL). Seabed slopes were in the range of 0.5% offshore to 1.5% closer to the beach. A smooth concrete structure will replace the existing concrete seawall with an elevated curved crown wall. Prior the start of breaking (at -7 m MSL contour), storm-driven maximum spectral significant wave heights of 2.8 m and 3.2 m were estimated for the benchmark historical storm event dated of 1997 and the 50-year return period storms respectively, resulting in 1 m high waves at the beach. For the wave load assessment, a tensor scale measured wave forces and moments and five piezo / piezo-resistive pressure sensors were placed on the wall. Light-weight sediment physical model and pressure and force measurements were performed with scale 1:18. The polyvinyl chloride light-weight particles used to model the prototype silty sand had a density of approximately 1 400 kg/m3 and a median diameter (d50) of 0.3 mm. Quantitative assessments of the seabed evolution were made using a measuring rod and also a laser scan survey. Testing demonstrated the occurrence of numerous impulsive wave impacts on the reflector (22%), induced not by direct wave breaking but mostly by wave run-up slamming on the top curved part of the wall. Wave forces of up to 264 kilonewtons and impulsive pressure spikes of up to 127 kilonewtons were measured. Maximum scour of -0.9 m was measured for the new seawall versus -0.6 m for the existing seawall, which is imputable to increased wave reflection (coefficient was 25.7 - 30.4% vs 23.4 - 28.6%). This paper presents a methodology for the setup and operation of a physical model in order to assess the hydrodynamic and morphodynamic processes at a beach seawall during storms events. It discusses the pros and cons of such methodology versus others, notably regarding structures peculiarities and model effects.

Keywords: beach, impacts, scour, seawall, waves

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Authors: Shorena Sadzaglishvili, Teona Gotsiridze, Ketevan Lekishvili, Darejan Javakhishvili, Alida Bouris

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Globally, adolescents and young people experience high levels of HIV vulnerability and risk. Estimates suggest that AIDS-related deaths among young people are increasing, suggesting poor prioritization of adolescents in national plans for HIV testing and treatment services. HIV/AIDS is currently the sixth leading cause of death in people aged 10-24 years. Among young people, street connected youth are clearly distinguished as being among the most at risk for HIV infection. The present study recognizes the urgent need to scale up effective HIV responses that are tailored to the unique needs of street connected youth for the global HIV agenda and especially, the former Soviet country - Georgia, where 'street kids' are a new phenomenon and estimated to be about 2,500. During two months trained interviewers conducted individual semi-structured qualitative interviews with 22 key informants from the local governmental and nongovernmental service organizations, including psychologists, social workers, peer educators, mobile health workers, and managers. Informants discussed social network characteristics influencing street connected youth’s sexual risk behaviors. Data were analyzed using Dedoose. It was revealed that there are three types of homogeneous networks of street-connected youth aged 10-19 based on ethnical background: (1) Georgians; (2) migrant kids of Azeri-Kurdish origin, and (3) local Roma-Moldavian kids. These networks are distinguished with various HIV risk through both risky sexual and drug-related behaviors. In addition, there are several cases of HIV infection identified through reactive social services. Street connected youth do not have basic information about the HIV related sexual, alcohol and drug behaviors nor there are any systematic programs providing HIV testing and consultation for reducing the vulnerability of HIV infection. There is a need to systematically examine street-connected youth risk-taking behaviors by applying an integrated, multilevel framework to a population at great risk of HIV. Acknowledgment: This work was supported by Shota Rustaveli National Science Foundation of Georgia (SRNSFG) [#FR 17_31], Ilia State University.

Keywords: street connected youth, social networks, HIV/AIDS, HIV testing

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Authors: R. Marhenke, M. Martini

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The distraction of attentional resources after learning hinders long-term memory consolidation compared to several minutes of post-encoding inactivity in form of wakeful resting. We tested whether an 8-minute period of wakeful resting, compared to performing an adapted version of the d2 test of attention after learning, supports memory retention. Participants encoded and immediately recalled a word list followed by either an 8 minute period of wakeful resting (eyes closed, relaxed) or by performing an adapted version of the d2 test of attention (scanning and selecting specific characters while ignoring others). At the end of the experimental session (after 12-24 min) and again after 7 days, participants were required to complete a surprise free recall test of both word lists. Our results showed no significant difference in memory retention between the experimental conditions. However, we found that participants who completed the first lines of the d2 test in less than the given time limit of 20 seconds and thus had short unfilled intervals before switching to the next test line, remembered more words over the 12-24 minute and over the 7 days retention interval than participants who did not complete the first lines. This interaction occurred only for the first test lines, with the highest temporal proximity to the encoding task and not for later test lines. Differences in retention scores between groups (completed first line vs. did not complete) seem to be widely independent of the general performance in the d2 test. Implications and limitations of these exploratory findings are discussed.

Keywords: long-term memory, retroactive interference, attention, forgetting

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Authors: Adel. M. Sharaf, Foad H. Gandoman

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Nowadays, Photovoltaic-PV Farms/ Parks and large PV-Smart Grid Interface Schemes are emerging and commonly utilized in Renewable Energy distributed generation. However, PV-hybrid-Dc-Ac Schemes using interface power electronic converters usually has negative impact on power quality and stabilization of modern electrical network under load excursions and network fault conditions in smart grid. Consequently, robust FACTS based interface schemes are required to ensure efficient energy utilization and stabilization of bus voltages as well as limiting switching/fault onrush current condition. FACTS devices are also used in smart grid-Battery Interface and Storage Schemes with PV-Battery Storage hybrid systems as an elegant alternative to renewable energy utilization with backup battery storage for electric utility energy and demand side management to provide needed energy and power capacity under heavy load conditions. The paper presents a robust interface PV-Li-Ion Battery Storage Interface Scheme for Distribution/Utilization Low Voltage Interface using FACTS stabilization enhancement and dynamic maximum PV power tracking controllers. Digital simulation and validation of the proposed scheme is done using MATLAB/Simulink software environment for Low Voltage- Distribution/Utilization system feeding a hybrid Linear-Motorized inrush and nonlinear type loads from a DC-AC Interface VSC-6-pulse Inverter Fed from the PV Park/Farm with a back-up Li-Ion Storage Battery.

Keywords: AC FACTS, smart grid, stabilization, PV-battery storage, Switched Filter-Compensation (SFC)

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Authors: Busra Nur Ozguler Aktel

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This research aims to understand the factors that affect the ways in which tribes perceive and respond to violent conflicts in fragile states, given that tribes are essential stakeholders in many conflict-ridden fragile states, whether Afghanistan, Iraq, Syria, Libya, Somalia, Nigeria, or Yemen. It explores the primary questions of why some tribes align with extremist groups while others align with states during civil wars and why some tribes switch alignments. It argues that tribes form and switch alignments based on their perception of threats to their traditional tribal structure (internal dynamics) and clientelist relationships (external dynamics). Put differently; threat perceptions lead them to choose either the state or extremist groups that will more likely secure their traditional structure and patronage networks. This study focuses on Iraqi tribes as a case study. It builds a theory of tribal alignment formation based on ethnographic fieldwork in the Middle East, with a particular focus on Iraqi Sunni tribes living in the Kurdish region of Iraq and Jordan. As a result of the interviews with tribal leaders and members, local journalists, researchers, and politicians, it concludes that complex (re)alignments of tribes can determine the course and outcome of the conflicts, either mitigating or escalating violence. This study contributes to the larger body of conflict management and peacebuilding literature by introducing tribes as non-state actors and exploring their interactions with other actors in civil wars.

Keywords: civil wars, tribes, alignment formation, side-switching, Iraq

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Authors: Nadish Anand, Richard D. Gould

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A simplistic model is introduced for determining the thermal characteristics of a Low-rise Residential (LRR) building and then predicts the energy usage by its Heating Ventilation & Air Conditioning (HVAC) system according to changes in weather conditions which are reflected in the Ambient Temperature (Outside Air Temperature). The LRR buildings are treated as a simple lump for solving the heat transfer problem and the model is derived using the lumped capacitance model of transient conduction heat transfer from bodies. Since most contemporary HVAC systems have a thermostat control which will have an offset temperature and user defined set point temperatures which define when the HVAC system will switch on and off. The aim is to predict without any error the Body Temperature (i.e. the Inside Air Temperature) which will estimate the switching on and off of the HVAC system. To validate the mathematical model derived from lumped capacitance we have used EnergyPlus simulation engine, which simulates Buildings with considerable accuracy. We have predicted through the low order model the Inside Air Temperature of a single house kept in three different climate zones (Detroit, Raleigh & Austin) and different orientations for summer and winter seasons. The prediction error from the model for the same day as that of model parameter calculation has showed an error of < 10% in winter for almost all the orientations and climate zones. Whereas the prediction error is only <10% for all the orientations in the summer season for climate zone at higher latitudes (Raleigh & Detroit). Possible factors responsible for the large variations are also noted in the work, paving way for future research.

Keywords: building energy, energy consumption, energy+, HVAC, low order model, lumped capacitance

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Authors: Therese Besnard

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Internationally in early childhood education (ECE), the great majority of teachers are women. Some groups believe that a greater male teacher presence in ECE would be beneficial for children, specifically for boys as it could offer a positive male model. It is a common belief that children would benefit from being exposed to both male and female models. Some believe that women are naturally better suited to offer quality care to young children comparatively to men. Some authors bring forth that after equivalent training, differences in the educational practices are purely individual and do not depend on the teacher’s gender. Others believe that a greater male presence in ECE would increase the risk of pedophilia or child abuse. The few scientific studies in this area suggest that differences could exist between male and female ECE teacher, in particular when it comes to play which is the mainstay of the ECE educational program. Male teachers describe themselves as being more playful and having a greater tendency to initiate physical and turbulent play comparatively to female teachers, who describe themselves as favoring games that are calmer and focused on social interaction. Observed directly, male teachers appear more actively engaged in play with children and propose more motor play than female teachers. Furthermore children who have both male and female teachers for one year show less behavior difficulties when compared to children with only female teachers. Despite a variety of viewpoints we don’t know if the educational practices of male ECE teachers, (emotional support, classroom organization or instructional support) are different than the educational practices of female teachers and if these practices are linked with children’s adaptation. This study compares the educational practices of 37 ECE teachers (57 % male) and analyses the link with children' social adaptation (n=221). Educational practices were assessed through observational measurements with the Classroom Assessment Scoring System (CLASS) in a natural class environment. Child social adaptation was assessed with the Social Competence and Behavior Evaluation (SCBE). Observational data reveals no differences between men's and women's scale of the CLASS. Results using Multilevel models analyses suggest that the ability to propose good classroom organization and give good instructional support are linked with better child' social adaptation, and that is always true for men and women teachers. The results are discussed on the basis of their potential impact on future educational interventions.

Keywords: child social adaptation, early childhood education, educational practices, men teacher

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Authors: Hedi Dghim, Ahmed El-Naggar, Istvan Erlich

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Power electronic converters are being introduced in low voltage (LV) grids at an increasingly rapid rate due to the growing adoption of power electronic-based home appliances in residential grid. Photovoltaic (PV) systems are considered one of the potential installed renewable energy sources in distribution power systems. This trend has led to high distortion in the supply voltage which consequently produces harmonic currents in the network and causes an inherent voltage unbalance. In order to investigate the effect of harmonic distortions, a case study of a typical LV grid configuration with high penetration of 3-phase and 1-phase rooftop mounted PV from southern Germany was first considered. Electromagnetic transient (EMT) simulations were then carried out under the MATLAB/Simulink environment which contain detailed models for power electronic-based loads, ohmic-based loads as well as 1- and 3-phase PV. Note that, the switching patterns of the power electronic circuits were considered in this study. Measurements were eventually performed to analyze the distortion levels when PV operating under different solar irradiance. The characteristics of the load-side harmonic impedances were analyzed, and their harmonic contributions were evaluated for different distortion levels. The effect of the high penetration of PV on the harmonic distortion of both positive and negative sequences was also investigated. The simulation results are presented based on case studies. The current distortion levels are in agreement with relevant standards, otherwise the Total Harmonic Distortion (THD) increases under low PV power generation due to its inverse relation with the fundamental current.

Keywords: harmonic distortion analysis, power quality, PV systems, residential distribution system

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Authors: René Haarhoff

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Consumers are constantly reminded of their responsibility towards the environment in a world where words such as global warming, carbon footprint, recycling or ‘green’’ everything has become common language. What was previously considered to be ordinary practices are in many instances frowned upon today and consumers are expected to individually contribute towards a greener mother earth. However unused recycle bins, single travelers in luxury cars, busy airports and vast deforested areas for new developments tell another story. The question arises whether the everyday man in the street really takes the responsibility to balance the three pillars of sustainability: the planet, its people and profit. Undeniably our activities impact on the environment where a healthy economy is needed in a fast paced global environment. The situation is further gloomed in instances where the consumer has paid for inclusive services which directly impacts on the environment. A prime example of this is the tourism industry: accommodation establishments or resorts include clean, daily washed towels and bedding, large bath tubs, inclusive use of electricity and water to name a few. This research evaluates environmentally friendly practices consumers follow at home and also when on holiday. Respondents at Bloemfontein airport, often using tourism products were included in the study. Results reveal that the majority of respondents state that they are concerned about the environment yet when questioned on donation towards endangered species, switching off lights in hotel rooms or using water sparingly a significant difference in results are evident. From the research results it is evident that consumers do not practice what they preach towards a greener environment.

Keywords: green, environment, consumer, tourism, sustainable practices

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Authors: S. Jalaja, A. M. Vijaya Prakash

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Recursive combination of an algorithm based on Karatsuba multiplication is exploited to design a generalized transpose and parallel Finite Impulse Response (FIR) Filter. Mid-range Karatsuba multiplication and Carry Save adder based on Karatsuba multiplication reduce time complexity for higher order multiplication implemented up to n-bit. As a result, we design modified N-tap Transpose and Parallel Symmetric FIR Filter Structure using Karatsuba algorithm. The mathematical formulation of the FFA Filter is derived. The proposed architecture involves significantly less area delay product (APD) then the existing block implementation. By adopting retiming technique, hardware cost is reduced further. The filter architecture is designed by using 90 nm technology library and is implemented by using cadence EDA Tool. The synthesized result shows better performance for different word length and block size. The design achieves switching activity reduction and low power consumption by applying with and without retiming for different combination of the circuit. The proposed structure achieves more than a half of the power reduction by adopting with and without retiming techniques compared to the earlier design structure. As a proof of the concept for block size 16 and filter length 64 for CKA method, it achieves a 51% as well as 70% less power by applying retiming technique, and for CSA method it achieves a 57% as well as 77% less power by applying retiming technique compared to the previously proposed design.

Keywords: carry save adder Karatsuba multiplication, mid range Karatsuba multiplication, modified FFA and transposed filter, retiming

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Authors: Rihab Hamdi, Amel Hadri Hamida, Fatiha Khelili, Sakina Zerouali, Ouafae Bennis

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This paper features a comparative study performance of sliding mode controller (SMC) for closed-loop voltage control of direct current to direct current (DC-DC) three-cells buck converter connected in parallel, operating in continuous conduction mode (CCM), based on pulse-width modulation (PWM) with SMC based on hysteresis modulation (HM) where an adaptive feedforward technique is adopted. On one hand, for the PWM-based SM, the approach is to incorporate a fixed-frequency PWM scheme which is effectively a variant of SM control. On the other hand, for the HM-based SM, oncoming an adaptive feedforward control that makes the hysteresis band variable in the hysteresis modulator of the SM controller in the aim to restrict the switching frequency variation in the case of any change of the line input voltage or output load variation are introduced. The results obtained under load change, input change and reference change clearly demonstrates a similar dynamic response of both proposed techniques, their effectiveness is fast and smooth tracking of the desired output voltage. The PWM-based SM technique has greatly improved the dynamic behavior with a bit advantageous compared to the HM-based SM technique, as well as provide stability in any operating conditions. Simulation studies in MATLAB/Simulink environment have been performed to verify the concept.

Keywords: DC-DC converter, hysteresis modulation, parallel multi-cells converter, pulse-width modulation, robustness, sliding mode control

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Authors: Din Eak Arathai

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The purpose of this research report is to investigate the language choice and use among the young generation of Malaysian Thais community. Besides that, it aims to investigate if there is a difference in language choice across the different domains. It will also examine if there has been a language shift from Thai to other languages by the young generation of Thai community in Malaysia. First the study focuses on the proficiency of Thai and other languages used by hundred (100) respondents belonging to young generation of Malaysian Thais aged range from 18-35. Next, language use and choice will be presented with a focus on the domains of family, friendship, entertainment and social. Finally, based on the findings and data collected, we will be able to see if language shift from Thai to other languages has occurred among the young Thai generation in Malaysia. The instrument used in this study was a 30-item questionnaire and the findings of the data analysis were presented in the form of frequency counts and percentages. The findings found that Thai language remains the most preferred language of choice among young Malaysian Thais but usage of other languages, such as Malay, English and Mandarin has increased and begun to influence the language choice of young Malaysian Thais and their proficiency of their mother tongue.In all the domains studied, Thai is almost exclusively the preferred language used when communicating with family. Malay is the most preferred language in communicating with friends while English is the most preferred language when communicating with colleagues. With regards to social and entertainment activities, young Malaysian Thais show great affinity for entertainment in the Thai language. In conclusion, the result of the study showed the beginning of young Malaysian Thais shifting to other languages, especially English and Malay through their daily choices when communicating with friends and family and especially through their language preferences in entertainment.

Keywords: language choice, language use, language shift, language maintenance, young Malaysian Thais, code switching, code mixing

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Authors: Asghar Arif

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Lung cancer has been recognized as one of the greatest common cancers, causing the annual mortality rate of about 1.2 million people in the world. Lung cancer is the most prevalent cancer in men and the third-most common cancer among women (after breast and digestive cancers).Recent evidences have shown the inflammatory process as one of the potential factors of cancer. Tuberculosis (TB), pneumonia, and chronic bronchitis are among the most important inflammation-inducing factors in the lungs, among which TB has a more profound role in the emergence of cancer.TB is one of the important mortality factors throughout the world, and 205,000 death cases are reported annually due to this disease. Chronic inflammation and fibrosis due to TB can induce genetic mutation and alternations. Parenchyma tissue of lung is involved in both diseases of TB and lung cancer, and continuous cough in lung cancer, morphological vascular variations, lymphocytosis processes, and generation of immune system mediators such as interleukins, are all among the factors leading to the hypothesis regarding the role of TB in lung cancer Some reports have shown that the induction of necrosis and apoptosis or TB reactivation, especially in patients with immune-deficiency, may result in increasing IL-17 and TNF_α, which will either decrease P53 activity or increase the expression of Bcl-2, decrease Bax-T, and cause the inhibition of caspase-3 expression due to decreasing the expression of mitochondria cytochrome oxidase. It has been also indicated that following the injection of BCG vaccine, the host immune system will be reinforced, and in particular, the rates of gamma interferon, nitric oxide, and interleukin-2 are increased. Therefore, CD4 + lymphocyte function will be improved, and the person will be immune against cancer.Numerous prospective studies have so far been conducted on the role of TB in lung cancer, and it seems that this disease is effective in that particular cancer.One of the main challenges of lung cancer is its correct and timely diagnosis. Unfortunately, clinical symptoms (such as continuous cough, hemoptysis, weight loss, fever, chest pain, dyspnea, and loss of appetite) and radiological images are similar in TB and lung cancer. Therefore, anti-TB drugs are routinely prescribed for the patients in the countries with high prevalence of TB, like Pakistan. Regarding the similarity in clinical symptoms and radiological findings of lung cancer, proper diagnosis is necessary for TB and respiratory infections due to nontuberculousmycobacteria (NTM). Some of the drug resistive TB cases are, in fact, lung cancer or NTM lung infections. Acid-fast staining and histological study of phlegm and bronchial washing, culturing and polymerase chain reaction TB are among the most important solutions for differential diagnosis of these diseases. Briefly, it is assumed that TB is one of the risk factors for cancer. Numerous studies have been conducted in this regard throughout the world, and it has been observed that there is a significant relationship between previous TB infection and lung cancer. However, to prove this hypothesis, further and more extensive studies are required. In addition, as the clinical symptoms and radiological findings of TB, lung cancer, and non-TB mycobacteria lung infections are similar, they can be misdiagnosed as TB.

Keywords: TB and lung cancer, TB people, TB servivers, TB and HIV aids

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Authors: Chia-Chi Chang, Chuan-Bi Lin, Chia-Min Chan

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Most ZigBee sensor networks to date make use of nodes with limited processing, communication, and energy capabilities. Energy consumption is of great importance in wireless sensor applications as their nodes are commonly battery-driven. Once ZigBee nodes are deployed outdoors, limited power may make a sensor network useless before its purpose is complete. At present, there are two strategies for long node and network lifetime. The first strategy is saving energy as much as possible. The energy consumption will be minimized through switching the node from active mode to sleep mode and routing protocol with ultra-low energy consumption. The second strategy is to evaluate the energy consumption of sensor applications as accurately as possible. Erroneous energy model may render a ZigBee sensor network useless before changing batteries. In this paper, we present a ZigBee wireless sensor node with four key modules: a processing and radio unit, an energy harvesting unit, an energy storage unit, and a sensor unit. The processing unit uses CC2530 for controlling the sensor, carrying out routing protocol, and performing wireless communication with other nodes. The harvesting unit uses a 2W solar panel to provide lasting energy for the node. The storage unit consists of a rechargeable 1200 mAh Li-ion battery and a battery charger using a constant-current/constant-voltage algorithm. Our solution to extend node lifetime is implemented. Finally, a long-term sensor network test is used to exhibit the functionality of the solar powered system.

Keywords: ZigBee, Li-ion battery, solar panel, CC2530

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Authors: Felipe M. de Freitas, Ícaro V. Soares, Lucas L. L. Fortes, Sandro T. M. Gonçalves, Úrsula D. C. Resende

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There is a dispersed energy in Radio Frequencies (RF) that can be reused to power electronics circuits such as: sensors, actuators, identification devices, among other systems, without wire connections or a battery supply requirement. In this context, there are different types of energy harvesting systems, including rectennas, coil systems, graphene and new materials. A secondary step of an energy harvesting system is the rectification of the collected signal which may be carried out, for example, by the combination of one or more Schottky diodes connected in series or shunt. In the case of a rectenna-based system, for instance, the diode used must be able to receive low power signals at ultra-high frequencies. Therefore, it is required low values of series resistance, junction capacitance and potential barrier voltage. Due to this low-power condition, voltage multiplier configurations are used such as voltage doublers or modified bridge converters. Lowpass filter (LPF) at the input, DC output filter, and a resistive load are also commonly used in the rectifier design. The electronic circuits projects are commonly analyzed through simulation in SPICE (Simulation Program with Integrated Circuit Emphasis) environment. Despite the remarkable potential of SPICE-based simulators for complex circuit modeling and analysis of quasi-static electromagnetic fields interaction, i.e., at low frequency, these simulators are limited and they cannot model properly applications of microwave hybrid circuits in which there are both, lumped elements as well as distributed elements. This work proposes, therefore, the electromagnetic modelling of electronic components in order to create models that satisfy the needs for simulations of circuits in ultra-high frequencies, with application in rectifiers coupled to antennas, as in energy harvesting systems, that is, in rectennas. For this purpose, the numerical method FDTD (Finite-Difference Time-Domain) is applied and SPICE computational tools are used for comparison. In the present work, initially the Ampere-Maxwell equation is applied to the equations of current density and electric field within the FDTD method and its circuital relation with the voltage drop in the modeled component for the case of lumped parameter using the FDTD (Lumped-Element Finite-Difference Time-Domain) proposed in for the passive components and the one proposed in for the diode. Next, a rectifier is built with the essential requirements for operating rectenna energy harvesting systems and the FDTD results are compared with experimental measurements.

Keywords: energy harvesting system, LE-FDTD, rectenna, rectifier, wireless power systems

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Authors: Ilze Pelece, Imants Ziemelis, Henriks Putans

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Traditionally the solar energy has been used in southern countries, but it has been used also in northern ones. Most popular kind of use of solar energy in Latvia is solar collector for water heating. Traditionally flat-plate solar collectors are used because of simplicity of manufacturing. However, some peculiarities in use of solar energy in northern countries must be taken into account. In northern countries, there is lower irradiance, but longer day and longer path of the sun during summer. Therefore traditional flat-plate solar collectors are not appropriate enough in northern countries, but new forms must be developed. There are two forms of solar collectors - cylindrical and semi-spherical – proposed in this work. Such collectors can be made both for water or air heating. Theoretical calculations and measurements of energy gain from those two collectors have been done. Results show that daily energy sum received by the semi-spherical collector from the sun at the middle of summer is 1.43 times more than that of the flat one, but for the cylindrical collector, it is 1.74 times more than that of the flat one or equal to that of the tracking to sun flat-plate collector. The resulting difference in energy gain from collector will be not so large because of the difference in heat loses. Heat can be decreased by switching off the water circulation pump when the sun is covered by clouds. For this purpose solar batteries, powered pump can be used instead of complicated and expensive automatics. Even more important than overall energy gain is the fact that semi-spherical and cylindrical collectors work all day (17 hours in the middle of summer at 57 northern latitudes), while flat-plate collector only about 11 hours. Yearly energy sum received by the collector from the sun is 1.5 and 1.9 times larger for the semi-spherical and cylindrical collector respectively as for the flat one. The cylindrical solar collector is easier to manufacture, but semi-spherical one is more aesthetical and durable against the impact of the wind. Although solar collectors for water and air heating are studied in this article, main ideas are applicable also for solar batteries.

Keywords: cylindric, semi-spherical, solar collector, solar energy, water heating

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Authors: Muhammad Siddique, Volodymyr Lugovskyy

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This paper explores how nations might mitigate the unfavorable impacts of oil price volatility on economic growth by switching to renewable energy sources. The impacts of uncertain factor prices on economic activity are examined by looking at the Realized Volatility (RV) of oil prices rather than the more traditional method of looking at oil price shocks. The United States of America (USA), China (C), India (I), United Kingdom (UK), Germany (G), Malaysia (M), and Pakistan (P) are all included to round out the traditional literature's examination of selected nations, which focuses on oil-importing and exporting economies. Granger Causality Tests (GCT), Impulse Response Functions (IRF), and Variance Decompositions (VD) demonstrate that in a Vector Auto-Regressive (VAR) scenario, the negative impacts of oil price volatility extend beyond what can be explained by oil price shocks alone for all of the nations in the sample. Different nations have different levels of vulnerability to changes in oil prices and other factors that may play a role in a sectoral composition and the energy mix. The conventional method, which only takes into account whether a country is a net oil importer or exporter, is inadequate. The potential economic advantages of initiatives to decouple the macroeconomy from volatile commodities markets are shown through simulations of volatility shocks in alternative energy mixes (with greater proportions of renewables). It is determined that in developing countries like Pakistan, increasing the use of renewable energy sources might lessen an economy's sensitivity to changes in oil prices; nonetheless, a country-specific study is required to identify particular policy actions. In sum, the research provides an innovative justification for mitigating economic growth's dependence on stable oil prices in our sample countries.

Keywords: oil price volatility, renewable energy, economic growth, developed and developing economies

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Authors: Wondmnew Derebe Yohannis

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The enhanced utilization of modern beehives holds significant potential to enhance the livelihoods of smallholder farmers who heavily rely on mixed crop-livestock farming for their income. Recognizing this, the distribution of improved beehives has been implemented across various regions in Ethiopia, including the Bugina district. However, the precise impact of these improved beehives on farmers' income has received limited attention. To address this gap, this study aims to assess the influence of adopting upgraded beehives on rural households' income and asset accumulation. To conduct this research, survey data was gathered from a sample of 350 households selected through random sampling. The collected data was then analyzed using an econometric stochastic frontier model (ESRM) approach. The findings reveal that the adoption of improved beehives has resulted in higher annual income and asset growth for beekeepers. On average, those who adopted the improved beehives earned approximately 6,077 Ethiopian Birr (ETB) more than their counterparts who did not adopt these beehives. However, it is worth noting that the impact of adoption would have been even greater for non-adopters, as evidenced by the negative transitional heterogeneity effect of 1792 ETB. Furthermore, the analysis indicates that the decision to adopt or not adopt improved beehives was driven by individual self-selection. The adoption of improved beehives also led to an increase in fixed assets for households, establishing it as a viable strategy for poverty reduction. Overall, this study underscores the positive effect of adopting improved beehives on rural households' income and asset holdings, showcasing its potential to uplift smallholder farmers and serve as an alternative mechanism for reducing poverty.

Keywords: impact, adoption, endogenous switching regression, income, improved beehives

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Authors: Beatriz Muñiz Cano, J. Ripoll Sau, D. Pacile, P. M. Sheverdyaeva, P. Moras, J. Camarero, R. Miranda, M. Garnica, M. A. Valbuena

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Graphene, in its pristine state, is a semiconductor with a zero band gap and massless Dirac fermions carriers, which conducts electrons like a metal. Nevertheless, the absence of a bandgap makes it impossible to control the material’s electrons, something that is essential to perform on-off switching operations in transistors. Therefore, it is necessary to generate a finite gap in the energy dispersion at the Dirac point. Intense research has been developed to engineer band gaps while preserving the exceptional properties of graphene, and different strategies have been proposed, among them, quantum confinement of 1D nanoribbons or the introduction of super periodic potential in graphene. Besides, in the context of developing new 2D materials and Van der Waals heterostructures, with new exciting emerging properties, as 2D transition metal chalcogenides monolayers, it is fundamental to know any possible interaction between chalcogenide atoms and graphene-supporting substrates. In this work, we report on a combined Scanning Tunneling Microscopy (STM), Low Energy Electron Diffraction (LEED), and Angle-Resolved Photoemission Spectroscopy (ARPES) study on a new superstructure when Te is evaporated (and intercalated) onto graphene over Ir(111). This new superstructure leads to the electronic doping of the Dirac cone while the linear dispersion of massless Dirac fermions is preserved. Very interestingly, our ARPES measurements evidence a large band gap (~400 meV) at the Dirac point of graphene Dirac cones below but close to the Fermi level. We have also observed signatures of the Dirac point binding energy being tuned (upwards or downwards) as a function of Te coverage.

Keywords: angle resolved photoemission spectroscopy, ARPES, graphene, spintronics, spin-orbitronics, 2D materials, transition metal dichalcogenides, TMDCs, TMDs, LEED, STM, quantum materials

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