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Search Results: 1 - 10 of 6714 matches for " Tomá? ?ikola "
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Excitonic fine structure splitting in type-II quantum dots
Vlastimil K?ápek,Petr Klenovsky,Tomá? ?ikola
Physics , 2015, DOI: 10.1103/PhysRevB.92.195430
Abstract: Excitonic fine structure splitting in quantum dots is closely related to the lateral shape of the wave functions. We have studied theoretically the fine structure splitting in InAs quantum dots with a type-II confinement imposed by a GaAsSb capping layer. We show that very small values of the fine structure splitting comparable with the natural linewidth of the excitonic transitions are achievable for realistic quantum dot morphologies despite the structural elongation and the piezoelectric field. For example, varying the capping layer thickness allows for a fine tuning of the splitting energy. The effect is explained by a strong sensitivity of the hole wave function to the morphology of the structure and a mutual compensation of the electron and hole anisotropies. The oscillator strength of the excitonic transitions in the studied quantum dots is comparable to those with a type-I confinement which makes the dots attractive for quantum communication technology as emitters of polarization-entangled photon pairs.
What’s Wrong with Requirements Specification? An Analysis of the Fundamental Failings of Conventional Thinking about Software Requirements, and Some Suggestions for Getting it Right  [PDF]
Tom Gilb
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.39096
Abstract: We know many of our IT projects fail and disappoint. The poor state of requirements methods and practice is frequently stated as a factor for IT project failure. In this paper, I discuss what I believe is the fundamental cause: we think like programmers, not engineers and managers. We do not concentrate on value delivery, but instead on functions, on use-cases and on code delivery. Further, management is not taking its responsibility to make things better. In this paper, ten practical key principles are proposed, which aim to improve the quality of requirements specification.
Internal Resource Audit for Strategists—A Proposal  [PDF]
Tom Connor
iBusiness (IB) , 2011, DOI: 10.4236/ib.2011.33038
Abstract: It is the purpose of this article to suggest a structured approach to internal resource audit, which, whilst of necessity general-purpose in design, would be capable of adaptation to particular company cases. Consequently this paper does not aim at theory development, but to make a conceptual contribution to the art and practice of management. It will, however, offer some criticism of current theory from a management perspective.
Tensioned Metastable Fluid Detectors in Nuclear Security for Passively Monitoring of Special Nuclear Materials―Part A  [PDF]
Tom Grimes, Rusi Taleyarkhan
World Journal of Nuclear Science and Technology (WJNST) , 2011, DOI: 10.4236/wjnst.2011.13010
Abstract: This paper (constituting Part A) describes the transformational Tensioned Metastable Fluid Detector (TMFD) based method for “passive” detection of Special Nuclear Materials (SNMs) as related to nuclear security. Purdue University is developing novel, multi-purpose tension metastable fluid nuclear particle detectors by which multiple types of nuclear particles can be detected with high (90%+) intrinsic efficiency, spectroscopic capability, directional information, rapid response, large standoff and significant cost-savings compared with state-of-the-art systems. This paper focuses specifically on recent advances in the use of these novel detector systems for neutron spectroscopy. These techniques will then be discussed and evaluated in the context of area monitoring in waste processing applications with a focus on passive monitoring of radioactive source particles from SNMs. The companion paper (Part B) addresses TMFD technology as it pertains to active interrogation.
Pass/Fail Criterion for a Simple Radiation  [PDF]
Tom Burr, Avigdor Gavron
Modern Instrumentation (MI) , 2012, DOI: 10.4236/mi.2012.13004
Abstract: One of the simplest tests of a radiation portal monitor (RPM) is a series of n repeats (a vehicle drive-through) in which the ith repeat records a total number of counts Xi and alarms if Xi ≥ T where T is an alarm threshold. The RPM performance tests we consider use n repeats to estimate the probability p = P(Xi ≥ T). This paper addresses criterion A for testing RPMs, where criterion A is: for specified source strength, we must be at least 95% confident that p ≥ 0.5. To assess criterion A, we consider a distribution-free test and a test relying on assuming the counts Xi have approximately a Poisson distribution. Both test options require tolerance interval construction.
An Evaluation of the English Language Curriculum of the Nigeria Certificate in Education: A Case Study of a College of Education  [PDF]
Oris Tom-Lawyer
Open Journal of Social Sciences (JSS) , 2014, DOI: 10.4236/jss.2014.27011
Abstract: This treatise is a pilot study that evaluated the implementation of the English language curriculum of the Nigeria Certificate in Education at a College of Education in Ogun State, Nigeria. The certificate is the basic qualification for teaching. The poor performance of Nigerian students in external English examinations has continued to be a source of worry to parents, educational stakeholders and the government. This problem has impeded the transition to higher education of many Nigerian students. In order to proffer solution to this problem, the effectiveness of the training of English language teachers need to be examined. The study sought to fill the gap by evaluating the implementation of the English language curriculum of the NCE in order to determine the effectiveness of the schooling of teachers. In investigating these issues, a mixed methods approach was used to utilise a case study. The sample comprised ten lecturers and twenty students drawn through convenience sampling techniques. The instruments were questionnaires, observation checklists, interviews and field notes. The methods of analysis were descriptive/inferential statistics and thematic content analysis. The findings revealed that lecturers employed mostly a combination of teaching modes in classrooms. The resources (physical and human) were found to be inadequate and the school technologically deficient. Furthermore, the negative attitudes of the students impacted on the implementation of the curriculum. The study identified the ineffective implementation of the NCE English language curriculum. The paper recommends that parents and other stakeholders should thoroughly investigate teacher training.
Calibration of Nondestructive Assay Instruments: An Application of Linear Regression and Propagation of Variance  [PDF]
Stephen Croft, Tom Burr
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.55075
Abstract:

Several nondestructive assay (NDA) methods to quantify special nuclear materials use calibration curves that are linear in the predictor, either directly or as an intermediate step. The linear response model is also often used to illustrate the fundamentals of calibration, and is the usual detector behavior assumed when evaluating detection limits. It is therefore important for the NDA community to have a common understanding of how to implement a linear calibration according to the common method of least squares and how to assess uncertainty in inferred nuclear quantities during the prediction stage following calibration. Therefore, this paper illustrates regression, residual diagnostics, effect of estimation errors in estimated variances used for weighted least squares, and variance propagation in a form suitable for implementation. Before the calibration can be used, a transformation of axes is required; this step, along with variance propagation is not currently explained in available NDA standard guidelines. The role of systematic and random uncertainty is illustrated and expands on that given previously for the chosen practical NDA example. A listing of open-source software is provided in the Appendix.

Analysis on the Growth Rhythm and Cold Tolerance of Five-Year Old Eucalyptus benthamii Plantation for Bioenergy  [PDF]
Aihua Yu, Tom Gallagher
Open Journal of Forestry (OJF) , 2015, DOI: 10.4236/ojf.2015.56052
Abstract: A research plot of Eucalyptus benthamii was planted to evaluate this species’ ability to supply the emerging bioenergy markets that are developing in the southern U.S. The plot was planted in two different densities to investigate the growth parameters and the cold tolerance. The stand was measured annually through five growing seasons. The results indicated that the growth difference among the young E. benthamii was noticeable. For example, the maximum and minimum value of five-year old trees at diameter breast height (DBH) was 27.9 centimeters and 1.27 centimeters; and the maximum and minimum value of tree height was 22.86 meters and 2.44 meters, respectively. The yearly change in DBH and height of E. benthamii had significant differences. The average annual survival rates of E. benthamii had differences under the two planting densities (1650 trees ha-1 and 1237 trees ha-1). The densities also had effects on the height and DBH growth of E. benthamii. The average DBH and height of 1650 trees ha-1 plantation were 11.18 centimeters and 15.03 meters, and the average DBH and height of 1237 trees ha-1 plantation were 13.46 centimeters and 16.28 meters. The volume per hectare of 1650 trees ha-1 and 1237 trees ha-1 plantation were 111.45 cubic meters and 101.15 cubic meters, respectively. Average diameter growth was almost 2.54 centimeters per year and average height growth was over 3 meters. E. benthamii plantations were considered tolerant to -7.4 degrees Celsius and a cold spell during early 2014 (-11.3 degrees Celsius for two consecutive nights) killed the plantation. The growth of E. benthamii also
Rational Choice Theory: Toward a Psychological, Social, and Material Contextualization of Human Choice Behavior  [PDF]
Tom Burns, Ewa Roszkowska
Theoretical Economics Letters (TEL) , 2016, DOI: 10.4236/tel.2016.62022
Abstract: The main purpose of this paper is to provide a brief overview of the rational choice approach, followed by an identification of several of the major criticisms of RCT and its conceptual and empirical limitations. It goes on to present a few key initiatives to develop alternative, more realistic approaches which transcend some of the limitations of Rational Choice Theory (RCT). Finally, the article presents a few concluding reflections and a table comparing similarities and differences between the mainstream RCT and some of the initial components of an emerging choice theory. Our method has been to conduct a brief selective review of rational choice theoretical formulations and applications as well as a review of diverse critical literature in the social sciences where rational choice has been systematically criticized. We have focused on a number of leading contributors (among others, several Nobel Prize Recipients in economics, who have addressed rational choice issues). So this article makes no claim for completeness. The review maps a few key concepts and assumptions underpinning the conceptual model and empirical applications of RCT. It reviews also a range of critical arguments and evidence of limitations. It identifies selected emerging concepts and theoretical revisions and adaptations to choice theory and what they entail. The results obtained, based on our literature reviews and analyses, are the identification of several major limitations of RCT as well as selected modifications and adaptations of choice theory which overcome or promise to overcome some of the RCT limitations. Thus, the article with Table 1 in hand provides a point of departure for follow-up systematic reviews and more precise questions for future theory development. The criticisms and adaptations of RCT have contributed to greater realism, empirical relevance, and increased moral considerations. The developments entail, among other things: the now well-known cognitive limitations (“bounded rationality”) and, for instance, the role of satisficing rather than maximizing in decision-making to deal with cognitive complexity and the uncertainties of multiple values; choice situations are re-contextualized with psychology, sociology, economic, and material conditions and factors which are taken into account explicitly and insightfully in empirical and theoretical work. Part of the contextualization concerns the place of multiple values, role and norm contradictions, and moral dilemmas in much choice behavior. In conclusion, the article suggests that the adaptations and
Infrastructure and Coffee Exports’ Fluctuations in a Small Open Economy: Case of Togolese Economy  [PDF]
Tom-Irazou Tchalim
Modern Economy (ME) , 2016, DOI: 10.4236/me.2016.712130
Abstract: In the current context of boosting economic growth based on agriculture, the traditional determinants seem insufficient. It is therefore necessary to establish the role of non-classical factors that influence the evolution of agricultural exports. Thus, this paper aims to establish the role of transportation infrastructure in determining coffee exports in Togo’s economy. Firstly, the principal component analysis technique is used to construct a proxy of transportation infrastructure. Then the Error Correction Model is estimated under the gravity model framework. The data used in this study come mainly from FAO database, World Bank database and cover the period 1980-2014. The results reveal that transportation infrastructure is a good pillar for coffee exports enhancement in the short and long run. In addition, domestic production has a positive and significant effect on coffee exports. Regarding global factors, only the exchange rate affects long-term coffee exports. In terms of policy message, increase in transportation infrastructure investment is a strategy for increasing coffee exports.
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