The demographic transition: an attempt to reformulate a population theory.
Hofsten, E
1981-01-01
In this effort to reformulate the demographic transition theory, attention is directed to the following: Malthus and Karl Marx's criticism of his principle of population; the 1st stage of transition, i.e., high mortality, high fertility, and slow population growth; the 2nd stage of declining mortality; the 3rd stage of declining fertility; the 4th stage when mortality and fertility are both low; the growth potential; and the demographic transition in the 3rd world countries. The demographic transition theory has become popular among demographers, economists, historians, and others interested in studying the development of population over time since the end of World War 2. This interest has most likely been created by the anxiety over the population explosion in the 3rd world countries. Transition has made demographers believe that the period of rapid population growth will be automatically succeeded by a period of more or less constant population size. The question that arises is whether it is as simple as that. Demographic transition has to a great extent taken the place of Malthus' principle of population as a general theory of population. Demographic transition appears to describe in a satisfactory way the development of population which all currently industrialized countires have passed through, when going from the preindustrial to the present industrialized stage. The objectives to demographic transition as a general theory are considered. Some of the factors which have accounted for the decline in fertility in Europe may also apply to the 3rd world countries. 1 such factor is the effect of reduced infant and child mortality on the individual level. The fertility decline, caused by reduced infant and child mortality may, however, be of limited size. The great amount of unemployment in the 3rd world may affect fertility in a downward direction. The fertility decline in Europe occurred simultaneously with an industrialization process, which gradually covered the
THE SECOND DEMOGRAPHIC TRANSITION THEORY: A Review and Appraisal
Zaidi, Batool; Morgan, S. Philip
2017-01-01
References to the second demographic transition (SDT) concept/theoretical framework have increased dramatically in the last two decades. The SDT predicts unilinear change toward very low fertility and a diversity of union and family types. The primary driver of these changes is a powerful, inevitable and irreversible shift in attitudes and norms in the direction of greater individual freedom and self-actualization. First, we describe the origin of this framework and its evolution over time. Second, we review the empirical fit of the framework to major changes in demographic and family behavior in the U.S., the West, and beyond. As has been the case for other unilinear, developmental theories of demographic/family change, the SDT failed to predict many contemporary patterns of change/difference. Finally, we review previous critiques and identify fundamental weaknesses of this perspective, and provide brief comparisons to selected alternative approaches. PMID:28798523
Maitra, P
1992-06-01
The interrelationship between demographic transition, capitalist transformation, and technological change in the 2 contrasting cases of the UK and India is explored. In the UK, technological change evolved from the extensive to the intensive phase, while technological change was introduced in India from the UK and other developed economies. The Demographic Transition Model is re-examined for these cases while the extensive and intensive phases of technological change with their effects on labor demand and consequent effects on fertility rate are analyzed. Changes in economic structure, demography, and factor pricing systems are presented as indicators of capitalist transformation of an economy. At the onset of capitalist transformation, population growth tends to decline as a result of increasing demand for labor in productive activities. Accordingly, the pattern of population growth depends upon the growth of demand for labor in productive activities which in turn depends upon the nature of the source of technological change; Demographic Transition theory ignores this point. Debate remains over whether imported technology, once reaching maturity, may effect capitalist transformation of economies toward true integrated development.
Learning-by-doing, population pressure, and the theory of demographic transition.
Strulik, H
1997-01-01
The long-term effects of two interdependent relations between economic growth and population growth are discussed. The empirical work of Boserup (1981) was utilized, which focused on rural, sparsely populated economies with low income per capita. According to the formulation of the population-push hypothesis, learning-by-doing effects in production lead to increasing returns to scale and, therefore, to a positive correlation between economic and population growth. In accordance with the theory of demographic transition, the population growth rate initially increases with rising income levels and then declines. The approach originating from Cigno (1984) modified the economic model, which allowed the establishment of two different stable equilibria. Regarding this relationship, the existence and stability of low-income and high-income equilibrium was shown in a neoclassical growth model. Under plausible conditions a demo-economic transition from the first to the second steady-state took place. The instability of the Malthusian steady-state is also possible when a country develops along a path of economic growth which is compatible with the demographic transition. In this context, learning means the application of new techniques of agrarian production. In developed economies with a stable population the learning-or-doing decision lead to accumulation of human capital and the invention of new technologies and goods. The interdependence of income-determined population growth and learning-by-doing may serve as an explanation for the weak and partly controversial empirical support for an overall correlation between income and population growth. The result yielded a meaningful interpretation of the population-push hypothesis, which is consistent with the empirical findings on the correlation between economic and population growth.
THE PROCESS AND EFFECTS OF DEMOGRAPHIC TRANSITION IN PENANG, MALAYSIA
National Research Council Canada - National Science Library
Usman Haji Yaakob; Nik Norliati Fitri Md Nor
2013-01-01
This article describes the demographic transition in Penang, Malaysia based on the demographic transition theory, which explains the decline of birth and death rates in European countries during the 18th century...
Second demographic transition de-blocked?
Directory of Open Access Journals (Sweden)
Bobić Mirjana
2011-01-01
Full Text Available The text is re-examining the previously established dilemma related to whether Serbia (without Kosovo and Metohija is the country of second demographic transition, i.e.: has the transition been de-blocked, under the assumption that this is a worldwide historical process of transformation of industrialized countries. The last thesis, around which there exists a lot of controversy in the contemporary population theory, is however not dealt with in detail; to the contrary, it is used as the general theoretical framework for the exploration of the most recent tendencies in the transformation of nuptiality and fertility regime in Serbia, as well as in the western and countries in post-socialist transformation. Special attention is given to the ideational changes, more precisely to the specific features of the value profile of the Serbian population, which is one of the most important determinants of the societal framework, that acts in the back of the afore mentioned aggregate demographic indicators. Finally, the hypothesis is posed (which should be further investigated by means of in-depth research and complementary approach that the speeding-up of the second demographic transition and intensification of the individualisation not only of the partnership but of the parenthood as well, accompanied with the rise of living standard and social support to balancing work and family, would have produced important emancipating and, concomitantly, positive socioeconomic and demographic effects.
DEMOGRAPHIC SECURITY: THEORY, METHODOLOGY, EVALUATION
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Mikhail V. Karmanov
2015-01-01
Full Text Available The paper analyzes the theoretical aspects of demographic security. Reviewed and analyzed the point of view of various scholars to the definition of demographic security. The main directions of statistical analysis of demographic security.
Mortality versus Morbidity in the Demographic Transition
Aksan, Anna-Maria; Chakraborty, Shankha
2014-01-01
The link between the mortality and epidemiological transitions is used to identify the effect of the former on the fertility transition: a mortality transition that is not accompanied by improving morbidity causes slower demographic and economic change. In a model where children may die from infectious disease, childhood health affects human capital and noninfectious-disease-related adult mortality. When child mortality falls from lower prevalence, as it did in western Europe, labor productiv...
[The demographic transition in Latin America and Europe].
Zavala De Cosio, M E
1992-12-01
This work describes and analyzes the "European model of demographic transition" and compares it to the fertility transition in Latin America, arguing that two different types of demographic transition coexist in Latin America. Chesnais has defined 3 principal postulates of the theory of demographic transition that he believes are universally valid: the precedence in time of mortality decline; the occurrence of reproductive transition in 2 phases, limitation of marriages followed by limitation of births; and the influence of economic growth on the initiation of the secular fertiilty decline. This work is largely limited to discussion of the first 2 postulates. In all the European transitions analyzed, mortality has declined before the occurrence of fertility changes. Exceptions cited in the literature have probably been caused by omissions or other problems in the data. The level of mortality at the beginning of the transition and the rate of decline differ, giving unique character to each transition. Imbalances resulting from mortality decline are at the root of modern fertility transitions. The French demographic transition was distinguished by early appearance of birth limitation by married couples, as part of the regulation of population growth. In the rest of Europe, during the pretransitional period, the traditional system of reproduction was regulated primarily by control of nuptiality. Only at a second stage was marital fertiity controlled, when limitation of marriage was no longer sufficient or had exceeded the limits of social acceptability. All countries of Northern and Western Europe recorded increased proportions definitively single as the demographic situation began to change, until the moment when couples began to limit births. The demographic transition in Latin America began at the end of the 19th century, with mortality decline. Fertility increased initially in Latin America as it had in Europe and for the same reasons, but the impact was greater
Which transition comes first? Urban and demographic transitions in Belgium and Sweden
Directory of Open Access Journals (Sweden)
Philippe Bocquier
2015-12-01
Full Text Available Background: Several theories compete to explain the main drivers of urbanisation, past and present, in relation to both demographic transition and economic development. One hypothesis is that rural-to-urban migration is the driver of urbanisation; another is that urban mortality decline actually triggered urban transition. Objective: This paper reconsiders the relationship between demographic (vital migration and urban transitions by analysing the long-term contribution of natural and migratory movements to urban transition. The respective contributions of birth, death, and migration and their timing will indicate whether economic development, through labour force migration, or vital transition mainly determines urban transition. Methods: After examining the spatial dimension of the demographic transition theory, we use 19th and 20th century series on Sweden and Belgium to better identify the migration component of urban transition through the computation of growth difference between urban and rural areas, accounting for the often neglected reclassification effect. Results: In both Sweden and Belgium, migration is the direct or indirect (through reclassification engine of urban transition and its contribution precedes the onset of vital transition, while the vital transition has a secondary, unstable, and negative role in the urban transition. Conclusions: Changes in the economic sphere are reinstated as the underlying cause of population change, acting through the shift of human capital in space. Methodological consequences are then drawn for analysing vital and urban transitions in an increasingly interdependent world. Contribution: The paper contributes to the theoretical literature on urban and demographic transitions in relation to economic development. The proposed method evaluates migration contribution without having to measure it.
Variational Transition State Theory
Energy Technology Data Exchange (ETDEWEB)
Truhlar, Donald G. [Univ. of Minnesota, Minneapolis, MN (United States)
2016-09-29
This is the final report on a project involving the development and applications of variational transition state theory. This project involved the development of variational transition state theory for gas-phase reactions, including optimized multidimensional tunneling contributions and the application of this theory to gas-phase reactions with a special emphasis on developing reaction rate theory in directions that are important for applications to combustion. The development of variational transition state theory with optimized multidimensional tunneling as a useful computational tool for combustion kinetics involved eight objectives.
Administrative Theory in Transition.
Griffiths, Daniel E.
This monograph analyzes transition in educational administrative theory. A brief introductory section describes the theoretical movement, the substance and repercussions of Thomas Greenfield's critique of educational administrative theory in 1974, and emerging qualitative approaches. Seven readings, all written by the volume's author, view…
Demographic evidence for adaptive theories of aging.
Mitteldorf, J J
2012-07-01
Pleiotropic theories for the evolutionary origins of senescence have been ascendant for forty years (see, for example, G. Williams (1957) Evolution, 11, 398-411; T. Kirkwood (1977) Nature, 270, 301-304), and it is not surprising that interpreters of demographic data seek to frame their results in this context. But some of that evidence finds a much more natural explanation in terms of adaptive aging. Here we re-interpret the 1997 results of the Centenarian Study in Boston, which found in their sample of centenarian women an excess of late childbearing. The finding was originally interpreted as a selection effect: a metabolic link between late menopause and longevity. But we demonstrate that this interpretation is statistically strained, and that the data in fact indicate a causal link: bearing a child late in life induces a metabolic response that promotes longevity. This conclusion directly contradicts some pleiotropic theories of aging that postulate a "cost of reproduction", and it supports theories of aging as an adaptive genetic program.
Variational transition state theory
Energy Technology Data Exchange (ETDEWEB)
Truhlar, D.G. [Univ. of Minnesota, Minneapolis (United States)
1993-12-01
This research program involves the development of variational transition state theory (VTST) and semiclassical tunneling methods for the calculation of gas-phase reaction rates and selected applications. The applications are selected for their fundamental interest and/or their relevance to combustion.
Transition Theory – Sustainable Transition of Socio-Technical Systems
DEFF Research Database (Denmark)
Søndergård, Bent; Holm, Jesper; Stauning, Inger
2015-01-01
Theories of transition management, transition studies and social practise theory Applied to studies of hosuing and construction......Theories of transition management, transition studies and social practise theory Applied to studies of hosuing and construction...
Demographic shifts in the Czech Republic after 1989 : A second demographic transition view
Sobotka, T.; Zeman, K.; Kantorova, V.
2003-01-01
A dramatic change in fertility, family formation and living arrangements took place in the Czech Republic over the 1990s. The establishment of democracy, profound social transformation and transition to the market economy affected the values and demographic behaviour of the young Czech generation.
Russian Federation : From the first to second demographic transition
Zakharov, Sergei
2008-01-01
The demographic transition in Russia was accelerated by several social cataclysms during the "Soviet type" modernization. Frequent changes in the timing of births and marriages engendered a mass "abortion culture". Contraceptive devices of poor quality were produced on a limited scale. The Soviet
vanden-Eijnden, E.
The dynamical behavior of many systems arising in physics, chemistry, biology, etc. is dominated by rare but important transition events between long lived states. For over 70 years, transition state theory (TST) has provided the main theoretical framework for the description of these events [17,33,34]. Yet, while TST and evolutions thereof based on the reactive flux formalism [1, 5] (see also [30,31]) give an accurate estimate of the transition rate of a reaction, at least in principle, the theory tells very little in terms of the mechanism of this reaction. Recent advances, such as transition path sampling (TPS) of Bolhuis, Chandler, Dellago, and Geissler [3, 7] or the action method of Elber [15, 16], may seem to go beyond TST in that respect: these techniques allow indeed to sample the ensemble of reactive trajectories, i.e. the trajectories by which the reaction occurs. And yet, the reactive trajectories may again be rather uninformative about the mechanism of the reaction. This may sound paradoxical at first: what more than actual reactive trajectories could one need to understand a reaction? The problem, however, is that the reactive trajectories by themselves give only a very indirect information about the statistical properties of these trajectories. This is similar to why statistical mechanics is not simply a footnote in books about classical mechanics. What is the probability density that a trajectory be at a given location in state-space conditional on it being reactive? What is the probability current of these reactive trajectories? What is their rate of appearance? These are the questions of interest and they are not easy to answer directly from the ensemble of reactive trajectories. The right framework to tackle these questions also goes beyond standard equilibrium statistical mechanics because of the nontrivial bias that the very definition of the reactive trajectories imply - they must be involved in a reaction. The aim of this chapter is to
Mortality-fertility synergies during the demographic transition in the developed world.
Sánchez-Barricarte, Jesús J
2017-07-01
The classic theory used to explain the demographic transition assumes that mortality is the key explanatory variable influencing the decline in fertility. However, the empirical results obtained in what is known as the Princeton European Fertility Project have led many specialists to question this assumption. Using both national and provincial aggregated data for 25 countries over a long time span, the analysis reported in this paper found that mortality does indeed play a fundamental role in accounting for the main demographic changes that occurred both before and during the transitional period. Others' research based on individual data has shown clearly that the number of surviving children was indeed an important factor for reproductive decisions. My analysis, using aggregated data, reached largely similar conclusions regarding the role of mortality in changing reproductive trends, via its impact on nuptiality and marital fertility at different stages of the demographic transition.
Demographic model of the Neolithic transition in Central Europe
Directory of Open Access Journals (Sweden)
Patrik Galeta
2009-12-01
Full Text Available Several recent lines of evidence indicate more intensive contact between LBK farmers and indigenous foragers in Central Europe (5600–5400 calBC. Strong continuity has been identified between Mesolithic and Neolithic material cultures; faunal assemblages, and isotopic analyses of diet have revealed a greater role of hunting in LBK communities; genetic analyses have suggested that the modern Central European gene pool is mainly of Palaeolithic origin. Surprisingly little attention has been paid to demographic aspects of the Neolithic transition. In our study, demographic simulations were performed to assess the demographic conditions that would allow LBK farmers to spread across central Europe without any admixture with Mesolithic foragers. We constructed a stochastic demographic model of changes in farming population size. Model parameters were constrained by data from human demography, archaeology, and human ecology. Our results indicate that the establishment of farming communities in Central Europe without an admixture with foragers was highly improbable. The demographic conditions necessary for colonization were beyond the potential of the Neolithic population. Our study supports the integrationists’ view of the Neolithic transition in Central Europe.
The Second Demographic Transition in Israel: One for All?
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Evgenia Bystrov
2012-08-01
Full Text Available This article explores family behaviours and attitudes in Israel over the last decades through the lens of the Second Demographic Transition (SDT. Israel is divided by religious affiliation, the level of religiosity, ethnic origin and timing of immigration. Although fertility transition to replacement level among certain societal groups has been previously shown, the question of how the transition unfolds in other domains remains open. The goal of this paper is to highlight the diversity of marital and fertility transitions and non-transitions among various groups of this heterogeneous society, and to compare Israel's transitions to European ones. The data sources which are used are cross-national large scale surveys, national representative surveys, and Population Register data. The data were disaggregated by religion, religiousness and ethnic origin. Emancipative value change, postponement of marriage, alternative living arrangements and a growing variety of fertility regimes were analyzed. A full range of pre-transitional, transitional, and post-transitional elements was found among the groups. Such sign of the SDT as growing childlessness was not found, and the spread of other features as unmarried cohabitation and non-marital childbearing was found limited. Population composition effects were isolated. It was found that the level of religiosity and the country of origin are important factors which differentiate family behaviours and attitudes. The connection between value orientation of the groups within Israel and their family behaviours is discussed. The socio-structural and institutional constraints that might impede further progression of the Second Demographic Transition in Israel are also discussed. Further research directions are suggested.
Turkey's Epidemiological and Demographic Transitions: 1931-2013.
Bakar, Coşkun; Oymak, Sibel; Maral, Işıl
2017-08-04
The causes of death have changed with regard to the epidemiological and demographic events in society. There is no evidence of prior research into the epidemiological transition in Turkey. This transition in Turkey should be observed starting with the Ottoman Empire period (19th to early 20th century). However, information about the Ottoman Empire is quite limited. To discuss the epidemiological and demographic transitions in Turkey, using demographic, educational and urbanization data in our present study. A descriptive archive study. Mortality statistics dating from 1931 and published by the Turkish Statistical Institute were analysed, and the causes of death were coded and classified according to ICD-10. Other data were obtained from the published reports and studies regarding the issue. In the 1930s, Turkey's life expectancy was low (aged 40 years), fertility and mortality rates were high (respectively 45% and 31%), and the main causes of death were infectious diseases. Nowadays, life expectancy is close to 80 years, the total fertility rate has dropped to 2.1 per woman, and the main causes of death are chronic diseases and cancer. The population rate in the urban areas has increased steadily from 24.2% in 1927 to 77.3% in 2012. level of education has also increased during this period. In 1935, less than 10% of women were literate, and in 2013 90% were literate. Qualitative and quantitative increase have been observed in the presentation and access of healthcare services compared to the early years of the Republic. Turkey has been undergoing a modernization period in the last 200 years, and it is believed that the epidemiological and demographic transitions result from this period. This process has led to urbanization and an increase in the level of education, as well as a decrease in premature deaths, lower fertility rates, and an increase in the elderly population and chronic diseases. It is therefore our conclusion that Turkey needs policies regarding the
Revolution without ideology: demographic transition in East Asia.
Anderson, T D
1980-01-01
The acceleration of demographic transition in East Asia is a process of great potential import for the world. The most rapid and large scale transformation of demographic pattern in world history is being accomplished in this region. Demographic processes in other countries and regions have been viewed in the light of past events. Demographic transition has been accepted as a desirable goal, but its realization was believed subject to certain constraints. These include the need to attain high rates of economic growth in order to stimulate the transition and the longer period of time required to accomplish the transition. It was assumed that at least 2 generations would be subject to gradually diminishing rates of increase and slow cultural modification before transition entered its last phase. This interpretation of the preconditions and specific character of demographic transition has been subject to increasing challenge, and recent events in East Asia accentuate such doubts. Most new views begin with the premises that contemporary pretransition societies are not European in culture and the 1970s are not the 1880s. East Asia also differs culturally from other developing areas, including South and Southeast Asia. The most significant regional features are cultural. Demographic transition in the region began after World War 2 and somewhat differently in each East Asian country. The process began first in Japan. The 3rd phase was accomplished rapidly but not as a specific consequence of the modernization process. The end of World War 2 and the spurt in births accompanying military demobilization contributed to a population surge. The cultural factors of practicality, homogeneity, social discipline, and nearly universial literacy were decisive here. Abortion was legalized in 1948 and other forms of birth control were made readily available. Between 1947 and 1957 the birthrate was halved to 17/1000. In Taiwan and South Korea public concern about high rates of
Status competition, inequality, and fertility: implications for the demographic transition.
Shenk, Mary K; Kaplan, Hillard S; Hooper, Paul L
2016-04-19
The role that social status plays in small-scale societies suggests that status may be important for understanding the evolution of human fertility decisions, and for understanding how such decisions play out in modern contexts. This paper explores whether modelling competition for status--in the sense of relative rank within a society--can help shed light on fertility decline and the demographic transition. We develop a model of how levels of inequality and status competition affect optimal investment by parents in the embodied capital (health, strength, and skills) and social status of offspring, focusing on feedbacks between individual decisions and socio-ecological conditions. We find that conditions similar to those in demographic transition societies yield increased investment in both embodied capital and social status, generating substantial decreases in fertility, particularly under conditions of high inequality and intense status competition. We suggest that a complete explanation for both fertility variation in small-scale societies and modern fertility decline will take into account the effects of status competition and inequality. © 2016 The Author(s).
Quantum Transition-State Theory
Hele, Timothy J H
2014-01-01
This dissertation unifies one of the central methods of classical rate calculation, `Transition-State Theory' (TST), with quantum mechanics, thereby deriving a rigorous `Quantum Transition-State Theory' (QTST). The resulting QTST is identical to ring polymer molecular dynamics transition-state theory (RPMD-TST), which was previously considered a heuristic method, and whose results we thereby validate. The key step in deriving a QTST is alignment of the flux and side dividing surfaces in path-integral space to obtain a quantum flux-side time-correlation function with a non-zero $t\\to 0_+$ limit. We then prove that this produces the exact quantum rate in the absence of recrossing by the exact quantum dynamics, fulfilling the requirements of a QTST. Furthermore, strong evidence is presented that this is the only QTST with positive-definite Boltzmann statistics and therefore the pre-eminent method for computation of thermal quantum rates in direct reactions.
van Poppel, F.W.A.; Reher, D.S.; Sanz-Gimeno, A.; Sanchez-Dominguez, M.; Beekink, E.
2012-01-01
BACKGROUND According to classic demographic transition theory, mortality change is the key factor that triggers a decline in fertility. Research on this topic has mostly relied on aggregate or time series data. Since fertility is based on the joint decisions of couples when confronted with specific
Institute of Scientific and Technical Information of China (English)
刘爽; 卫银霞; 任慧
2012-01-01
Based on a brief analysis of the narrowly-defined demographic transition and the classical model, this paper argues that the proposed theory of the second demographic transition broadly interprets the internal motivation and mechanism of action of the demographic changes by drawing upon the demographic ＂intermediate variables＂, reflecting on the relationship between modern demographic transition and social changes at the macro, meso and micro levels. Demographic transition is a multidimensional dynamic historical process, involving a set of transitions on marriage, reproduction, family, health, population control etc. Demographic transition is not only demographic change, but more importantly, is its nested social change. The unprecedented close relationship between the two reflects the social changes and social needs. Over the past 30 years China has made its population be adapted to economic development through family planning. In the next 30 to 50 years or even longer, China should make economic and social development be adapted to the changes and needs of the population. The end of development is to improve population survival and enhance life quality.%在扼要解析狭义人口转变及其经典模型的基础上，认为第二次人口转变的提出，是结合人口“中间变量”从广义上阐释了入口变化的内在动因与作用机理，进而在宏观、中观和微观三个层面引入了对现代人口转变与社会变迁关系的思考。主张人口转变是一个多维的动态历史过程，蕴涵着婚姻、生育、家庭、健康、人口调控等系列转变。提出第二次人口转变在中国的城市地区已露端倪。最后特别指出人口转变不仅仅是入口变化，更重要的是将其嵌套的社会变迁，两者关系的空前紧密折射着社会变化与社会需求。过去30年中国通过计划生育让人口“适应”了经济腾飞，而今后三、五十年以至更长时间，应使人口的“主
Transition delay using control theory.
Bagheri, S; Henningson, D S
2011-04-13
This review gives an account of recent research efforts to use feedback control for the delay of laminar-turbulent transition in wall-bounded shear flows. The emphasis is on reducing the growth of small-amplitude disturbances in the boundary layer using numerical simulations and a linear control approach. Starting with the application of classical control theory to two-dimensional perturbations developing in spatially invariant flows, flow control based on control theory has progressed towards more realistic three-dimensional, spatially inhomogeneous flow configurations with localized sensing/actuation. The development of low-dimensional models of the Navier-Stokes equations has played a key role in this progress. Moreover, shortcomings and future challenges, as well as recent experimental advances in this multi-disciplinary field, are discussed.
Demographics of Transition Discs in Ophiuchus and Taurus
Najita, Joan R; Muzerolle, James
2015-01-01
Transition disc systems are young stars that appear to be on the verge of dispersing their protoplanetary discs. We explore the nature of these systems by comparing the stellar accretion rates and disc masses of transition discs and normal T Tauri stars in Taurus and Ophiuchus. After controlling for the known dependencies of stellar accretion rate and disc mass and on age, stellar accretion rate on stellar mass, and disc mass on the presence of stellar or sub-stellar companions, we find that the normal T Tauri stars show a trend of stellar accretion rate increasing with disc mass. The transition discs tend to have higher average disc masses than normal T Tauri stars as well as lower accretion rates than normal T Tauri stars of the same disc mass. These results are most consistent with the interpretation that the transition discs have formed objects massive enough to alter the accretion flow, i.e., single or multiple giant planets. Several Ophiuchus T Tauri stars that are not known transition disc systems also...
Demographic transition and potential for development: the case of Iraqi Kurdistan.
Al-Hadithi, T S; Shabila, N R; Al-Tawil, N G; Othman, S M
2010-10-01
The effect of population growth and demographic transitionon economic developmenthas been well documented. The population growth in Iraqi Kurdistan is passing through a critical stage of demographic transition. It is, in fact, extremely likely that the region will fail to efficiently move through the demographic transition and will experience a long period in the demographic trap, i.e. the population will grow steadily and rapidly owing to the high fertility and low mortality rates. With correct government policies in terms of promoting family planning programmes, should the political context allow, demographic transition can pass smoothly through this critical stage. Furthermore, if demographic transition in Kurdistan moves to the next stage, it will provide an important window of opportunity for economic development. Proper exploitation of this demographic window through investment in education, on-the-job training and health services, in addition to proper and appropriate exploitation of economic resources and suitable and productive use of the labour force, will result in significant economic development over the next few decades.
Courtiol, Alexandre; Rickard, Ian J; Lummaa, Virpi; Prentice, Andrew M; Fulford, Anthony J C; Stearns, Stephen C
2013-05-20
Recent human history is marked by demographic transitions characterized by declines in mortality and fertility. By influencing the variance in those fitness components, demographic transitions can affect selection on other traits. Parallel to changes in selection triggered by demography per se, relationships between fitness and anthropometric traits are also expected to change due to modification of the environment. Here we explore for the first time these two main evolutionary consequences of demographic transitions using a unique data set containing survival, fertility, and anthropometric data for thousands of women in rural Gambia from 1956-2010. We show how the demographic transition influenced directional selection on height and body mass index (BMI). We observed a change in selection for both traits mediated by variation in fertility: selection initially favored short females with high BMI values but shifted across the demographic transition to favor tall females with low BMI values. We demonstrate that these differences resulted both from changes in fitness variance that shape the strength of selection and from shifts in selective pressures triggered by environmental changes. These results suggest that demographic and environmental trends encountered by current human populations worldwide are likely to modify, but not stop, natural selection in humans. Copyright © 2013 Elsevier Ltd. All rights reserved.
Final Technical Report: Variational Transition State Theory
Energy Technology Data Exchange (ETDEWEB)
Truhlar, Donald G. [University of Minnesota; Truhlar, Donald G. [University of Minnesota
2016-09-15
Complex molecules often have many structures (conformations) of the reactants and the transition states, and these structures may be connected by coupled-mode torsions and pseudorotations; some but not all structures may have hydrogen bonds in the transition state or reagents. A quantitative theory of the reaction rates of complex molecules must take account of these structures, their coupledmode nature, their qualitatively different character, and the possibility of merging reaction paths at high temperature. We have recently developed a coupled-mode theory called multi-structural variational transition state theory (MS-VTST) and an extension, called multi-path variational transition state theory (MP-VTST), that includes a treatment of the differences in the multidimensional tunneling paths and their contributions to the reaction rate. The MP-VTST method was presented for unimolecular reactions in the original paper and has now been extended to bimolecular reactions. The MS-VTST and MPVTST formulations of variational transition state theory include multi-faceted configuration-space dividing surfaces to define the variational transition state. They occupy an intermediate position between single-conformation variational transition state theory (VTST), which has been used successfully for small molecules, and ensemble-averaged variational transition state theory (EAVTST), which has been used successfully for enzyme kinetics. The theories are illustrated and compared here by application to three thermal rate constants for reactions of ethanol with hydroxyl radical—reactions with 4, 6, and 14 saddle points.
Lifetime reproduction and the second demographic transition: Stochasticity and individual variation
van Daalen, S.; Caswell, H.
2015-01-01
BACKGROUND In the last half of the previous century many developed countries went through a period of decreasing fertility rates, referred to as the second demographic transition. This transition is often measured using the Total Fertility Rate (TFR), which gives the mean number of children produced
Intergenerational Transmission of Reproductive Behavior during the Demographic Transition
Jennings, Julia A.; Sullivan, Allison R.; Hacker, J. David
2012-01-01
New evidence from the Utah Population Database (UPDB) reveals that at the onset of the fertility transition, reproductive behavior was transmitted across generations--between women and their mothers, as well as between women and their husbands' family of origin. Age at marriage, age at last birth, and the number of children ever born are positively correlated in the data, most strongly among first-born daughters and among cohorts born later in the fertility transition. Intergenerational ties, including the presence of mothers and mothers-in-law, influenced the hazard of progressing to a next birth. The findings suggest that the practice of parity-dependent marital fertility control and inter-birth spacing behavior derived in part from the previous generation and that the potential for mothers and mothers-in-law to help in the rearing of children encouraged higher marital fertility. PMID:22530253
The second demographic transition and the development level of Colombia departments, 2005
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Isabel C. Grajales A
2010-11-01
Full Text Available Objective: to analyze the behavior of some demographic characteristics for each department to identify the state of demographic transition and its relationship to the development level. Methodology: descriptive study based on secondary information sources published by the National Statistics Department and the National Planning Department. Results: the global fertility rate of the country was 2.5 in 2005. Chocó reported the highest rate whereas Bogotá reported the lowest. A total of 67% of Colombian states registered higher rates than the average rate in the country. Mortality rate of children in the country was 24.5, with the lowest rates registered in El Valle, Caldas, and Bogotá. The highest rates were registered in Arauca and Chocó. 26.6% of Colombian states show some advance in the demographic transition process. By contrast, 67% of the states are classified as lagged behind. There is a relation between the demographic transition index and the development indicators. Conclusion: Although some departments reach an advanced level of demographic transition, most of them still show high rates of infant mortality or fecundity which keep them behind in this process. Inequalities in living conditions of the country’s departments could be influencing the behavior of the demographic components analyzed.
Overview Chapter 6: The diverse faces of the Second Demographic Transition in Europe
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Tomáš Sobotka
2008-07-01
Full Text Available This chapter discusses the concept of the second demographic transition (SDT and its relevance for explaining the ongoing changes in family and fertility patterns across Europe. It takes a closer look at the shifts in values and attitudes related to family, reproduction, and children, and their representation in different chapters in this collection. It re-examines the link between the second demographic transition and fertility, highlights its strong positive association with fertility at later childbearing ages, and suggests that the transition does not necessarily lead to sub-replacement fertility levels. Subsequently, it provides an extensive discussion on the progression of the SDT behind the former 'Iron Curtain.' To explain some apparent contradictions in this process, it employs a conceptual model of 'readiness, willingness, and ability' (RWA advocated by Lesthaeghe and Vanderhoeft (2001. It also explores the multifaceted nature of the second demographic transition between different social groups, and points out an apparent paradox: whereas lower-educated individuals often embrace values that can be characterised as rather traditional, they also frequently manifest family behaviour associated with the transition, such as non-marital childbearing, high partnership instability, and high prevalence of long-term cohabitation. This suggests that there may be two different pathways of the progression of the second demographic transition. The concluding section points out the role of structural constraints for the diffusion of the transition among disadvantaged social strata, highlights the importance of the 'gender revolution' for the SDT trends, and discusses the usefulness of the SDT framework.
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Ron Lesthaeghe
2013-01-01
Full Text Available This is a study of how the synergisms between cultural and structural factors, which played a major role during the historical fertility and nuptiality transition (first demographic transition or FDT, have continued to condition demographic innovations connected to the "second demographic transition" (SDT. The continuity or discontinuity from the "first" to the "second" demographic transition is studied for spatial aggregates over more than a century in two national contexts, i.e., Belgium and Spain. Special attention is paid to the role of successive secularization waves in shaping the geographical patterns of both transitions. The study also shows that the maps of the two aspects of the SDT, i.e., the "postponement" and the "non-conformism" transitions respectively, are shaped by different determinants. Explanations are offered using the "Ready, Willing, and Able" paradigm, which allows us to uncover the different conditioning and limiting factors involved. The "non-conformist" transitions (control of marital fertility during the FDT and rise of cohabitation and non-conventional family formation during the SDT more closely mirror the history of secularization and the "Willingness" condition, whereas the fertility postponement aspect of the SDT mainly reflects female education and employment, or the "Readiness" condition. This generalization holds in both countries. However, in Belgium spatial continuity from FDT to SDT is connected to stable patterns of secularization, whereas in Spain it is linked to long standing differences with respect to female literacy and education.
How does variance in fertility change over the demographic transition?
Hruschka, Daniel J; Burger, Oskar
2016-04-19
Most work on the human fertility transition has focused on declines in mean fertility. However, understanding changes in the variance of reproductive outcomes can be equally important for evolutionary questions about the heritability of fertility, individual determinants of fertility and changing patterns of reproductive skew. Here, we document how variance in completed fertility among women (45-49 years) differs across 200 surveys in 72 low- to middle-income countries where fertility transitions are currently in progress at various stages. Nearly all (91%) of samples exhibit variance consistent with a Poisson process of fertility, which places systematic, and often severe, theoretical upper bounds on the proportion of variance that can be attributed to individual differences. In contrast to the pattern of total variance, these upper bounds increase from high- to mid-fertility samples, then decline again as samples move from mid to low fertility. Notably, the lowest fertility samples often deviate from a Poisson process. This suggests that as populations move to low fertility their reproduction shifts from a rate-based process to a focus on an ideal number of children. We discuss the implications of these findings for predicting completed fertility from individual-level variables. © 2016 The Author(s).
Shenk, Mary K
2009-01-01
Over the last three decades many authors have addressed the demographic transition from the perspective of evolutionary theory. Some authors have emphasized parental investment factors such as the costs of raising children, others have emphasized the effects of mortality and other forms of risk, and others have emphasized the biased transmission of cultural norms from people of high status. Yet the literature says little about the relative strengths of each of these types of motivations or about which ones are more likely to serve as the primary impetus for large-scale demographic change. In this paper, I examine how each of these factors has influenced the demographic transition in urban South India during the course of the 20th century using two measures of fertility transition: number of surviving children and age at marriage. I find that investment-related, risk-related, and cultural transmission predictors all have significant individual effects on the outcome variables, which persist when they are entered in combination. When the three types of predictors are compared, however, investment-related models appear to provide more robust explanations for patterns in both fertility and age of marriage. 2009 Wiley-Liss, Inc.
Cosmological phase transitions from lattice field theory
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Jansen, Karl [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany). John von Neumann-Inst. fuer Computing NIC
2011-11-22
In this proceedings contribution we discuss the fate of the electroweak and the quantum chromodynamics phase transitions relevant for the early stage of the universe at non-zero temperature. These phase transitions are related to the Higgs mechanism and the breaking of chiral symmetry, respectively. We will review that non-perturbative lattice field theory simulations show that these phase transitions actually do not occur in nature and that physical observables show a completely smooth behaviour as a function of the temperature.
The trade-off between fertility and education : evidence from before the demographic transition
Becker, Sascha O.; Cinnirella, Francesco; Woessmann, Ludger
2010-01-01
The trade-off between child quantity and education is a crucial ingredient of unified growth models that explain the transition from Malthusian stagnation to modern growth. We present first evidence that such a trade-off indeed existed before the demographic transition, exploiting a unique census-based dataset of 334 Prussian counties in 1849. Estimating two separate instrumental-variable models that instrument education by landownership inequality and distance to Wittenberg and fertility by ...
Potarca, Gina; Mills, Melinda; Lesnard, Laurent
2013-01-01
This study examines family formation trajectories as a manifestation of the second demographic transition (SDT) in three countries, comparing and contrasting two post-socialist countries (Romania and the Russian Federation) with France as benchmark country advanced in the SDT. By examining combined
Partner relationships in the Netherlands: new manifestations of the Second Demographic Transition
J.J. Latten; C.H. Mulder
2013-01-01
Partnership formation has rapidly and profoundly changed in theNetherlandssince the 1960s.Several scholars have placed these changes in the context of the Second Demographic Transition. We describe the main trends in the formation and dissolution of partnerships in theNetherlandsbetween the 1960/197
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2004-04-01
Full Text Available The core issue in this article is the empirical tracing of the connection between a variety of value orientations and the life course choices concerning living arrangements and family formation. The existence of such a connection is a crucial element in the so-called theory of the Second Demographic Transition (SDT. The underlying model is of a recursive nature and based on two effects: firstly, values-based self-selection of individuals into alternative living arrangement or household types, and secondly, event-based adaptation of values to the newly chosen household situation. Any testing of such a recursive model requires the use of panel data. Failing these, only "footprints" of the two effects can be derived and traced in cross-sectional data. Here, use is made of the latest round of the European Values Surveys of 1999-2000, mainly because no other source has such a large selection of value items. The comparison involves two Iberian countries, three western European ones, and two Scandinavian samples. The profiles of the value orientations are based on 80 items which cover a variety of dimensions (e.g. religiosity, ethics, civil morality, family values, social cohesion, expressive values, gender role orientations, trust in institutions, protest proneness and post-materialism, tolerance for minorities etc.. These are analysed according to eight different household positions based on the transitions to independent living, cohabitation and marriage, parenthood and union dissolution. Multiple Classification Analysis (MCA is used to control for confounding effects of other relevant covariates (age, gender, education, economic activity and stratification, urbanity. Subsequently, Correspondence Analysis is used to picture the proximities between the 80 value items and the eight household positions. Very similar value profiles according to household position are found for the three sets of countries, despite the fact that the onset of the SDT in
Many-Body Theory of Atomic Transitions
Holmes, Charles Potter
This dissertation presents a systematic approach to the derivation of transition widths and cross sections for atomic radiative and/or nonradiative processes. By applying the transition theory of Goldberger and Watson ^1, all transition properties are derived from proper solutions of the time-dependent Schrodinger equation. The focus is on situations where initial and final wave functions are nonorthogonal functions that belong to different self-consistent fields. This approach is particularly useful in the treatment of ionizing transitions where the outgoing free electron sees a different atomic potential from that of the initial bound state. Transition amplitudes are expressed as perturbation expansions in which singularities have been removed algebraically. These singularities are due to states which are degenerate with the initial and final states and represent the competing transition channels. The perturbation expansions show clearly the role of the nonorthogonality of the participating states leading to terms representing "shake" processes competing with higher-order electron correlation processes. Transition amplitudes including all second-order processes, are derived for the following transitions: X-ray, Auger, photoionization, radiative recombination, dielectronic recombination, radiative -Auger. Comparisons are made with the expressions frequently used by other workers. Using a Hartree-Fock-Slater model K- and L-shell X-ray and Auger transition widths are calculated for the range 5 Z Theory, (John Wiley & Sons, New York, 1964), Chapter 8, page 424.
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Martin Dribe
2014-07-01
Full Text Available Background: Despite a long interest in the historical fertility transition, there is still a lack of knowledge about disaggregated patterns that could help us understand the mechanisms behind the transition. In previous research the widely held view is that there was a change in the association between social status and fertility in conjunction with the fertility transition, implying that fertility went from being positively connected to social status (higher status was connected with higher fertility to being negatively associated with fertility. Objective: The aim of this collection is to study socioeconomic patterns in the fertility transition in a variety of contexts using similar approaches and measures of socioeconomic status. Methods: All contributions use different kinds of micro-level socioeconomic and demographic data and statistical models in the analysis. Data either come from census-like records or population registers. Conclusions: There is no consistent evidence for the hypothesis that socioeconomic status was positively related to fertility before the demographic transition. While such a correlation was clearly present in some contexts it was clearly not in other contexts. There is more unanimous support for the idea that the upper-and middle classes acted as forerunners in the transition, while especially farmers were late to change their fertility behavior. It is also evident that both parity-specific stopping and prolonged birth intervals (spacing were important in the fertility transition.
Demographic forecasts, migration and transition theory: a labor market perspective
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Michele BRUNI
2009-01-01
Full Text Available El trabajo propone un nuevo sistema lógico para construir escenarios demográficos basados en un modelo que explique los flujos entrantes de migración como una función de las necesidades de mano de obra que países con tasas de fecundidad por debajo de los niveles de remplazo están experimentando como resultado del declive de la población en edad laboral y el crecimiento del empleo. Usando este enfoque mostramos que la población en edad laboral (PEL de los países caracterizados por un bajo nivel de fecundidad necesariamente crecerá; que el balance migratorio de numerosos países cambiará de negativo a positivo bastante antes de 2050; que el nivel de los flujos migratorios internaciones progresivamente incrementará hasta valores no vistos de manera que entre 250 y 300 millones de personas migrarán de países en desarrollo hacia desarrollados en los siguientes 50 años; que el declive en fecundidad y el crecimiento relativo de las tasas de empleo de países desarrollados y en desarrollo determinará cambios radicales en el patrón de las migraciones internacionales.
The Developed World's Demographic Transition - the Roles of Capital Flows, Immigration, and Policy
Hans Fehr; Sabine Jokisch; Laurence Kotlikoff
2003-01-01
The developed word stands at the fore of a phenomenal demographic transition. Over the next 30 years the number of elderly in the U.S., the EU, and Japan will more than double. At the same time, the number of workers available to pay the elderly their government-guaranteed pension and health care benefits will rise by less than 10 percent. The fiscal implications of these two demographic trends are alarming. Paying promised benefits will, it appears, require a doubling or more of payroll tax ...
Transition-state theory and dynamical corrections
DEFF Research Database (Denmark)
Henriksen, Niels Engholm; Hansen, Flemming Yssing
2002-01-01
. The correction factor due to non-adiabatic dynamics is considered in relation to the non-activated dissociative sticking of N-2 on Fe(111). For this process, conventional transition-state theory gives a sticking probability which is about 10 times too large (at T = 300 K). We estimate that the sticking......We consider conventional transition-state theory, and show how quantum dynamical correction factors can be incorporated in a simple fashion, as a natural extension of the fundamental formulation. Corrections due to tunneling and non-adiabatic dynamics are discussed, with emphasis on the latter...
Theory of phase transitions rigorous results
Sinai, Ya G
1982-01-01
Theory of Phase Transitions: Rigorous Results is inspired by lectures on mathematical problems of statistical physics presented in the Mathematical Institute of the Hungarian Academy of Sciences, Budapest. The aim of the book is to expound a series of rigorous results about the theory of phase transitions. The book consists of four chapters, wherein the first chapter discusses the Hamiltonian, its symmetry group, and the limit Gibbs distributions corresponding to a given Hamiltonian. The second chapter studies the phase diagrams of lattice models that are considered at low temperatures. The no
Kuate Defo, Barthélémy
2014-01-01
Background Studies of trends in population changes and epidemiological profiles in the developing world have overwhelmingly relied upon the concepts of demographic, epidemiological, and health transitions, even though their usefulness in describing and understanding population and health trends in developing countries has been repeatedly called into question. The issue is particularly relevant for the study of population health patterns in Africa and sub-Saharan Africa, as the history and experience there differs substantially from that of Western Europe and North America, for which these concepts were originally developed. Objective The aim of this study is two-fold: to review and clarify any distinction between the concepts of demographic transition, epidemiological transition and health transition and to identify summary indicators of population health to test how well these concepts apply in Africa. Results Notwithstanding the characteristically diverse African context, Africa is a continent of uncertainties and emergencies where discontinuities and interruptions of health, disease, and mortality trends reflect the enduring fragility and instability of countries and the vulnerabilities of individuals and populations in the continent. Africa as a whole remains the furthest behind the world's regions in terms of health improvements and longevity, as do its sub-Saharan African regions and societies specifically. This study documents: 1) theoretically and empirically the similarities and differences between the demographic transition, epidemiological transition, and health transition; 2) simple summary indicators that can be used to evaluate their descriptive and predictive features; 3) marked disparities in the onset and pace of variations and divergent trends in health, disease, and mortality patterns as well as fertility and life expectancy trajectories among African countries and regions over the past 60 years; 4) the rapid decline in infant mortality and gains
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Barthélémy Kuate Defo
2014-05-01
Full Text Available Background: Studies of trends in population changes and epidemiological profiles in the developing world have overwhelmingly relied upon the concepts of demographic, epidemiological, and health transitions, even though their usefulness in describing and understanding population and health trends in developing countries has been repeatedly called into question. The issue is particularly relevant for the study of population health patterns in Africa and sub-Saharan Africa, as the history and experience there differs substantially from that of Western Europe and North America, for which these concepts were originally developed. Objective: The aim of this study is two-fold: to review and clarify any distinction between the concepts of demographic transition, epidemiological transition and health transition and to identify summary indicators of population health to test how well these concepts apply in Africa. Results: Notwithstanding the characteristically diverse African context, Africa is a continent of uncertainties and emergencies where discontinuities and interruptions of health, disease, and mortality trends reflect the enduring fragility and instability of countries and the vulnerabilities of individuals and populations in the continent. Africa as a whole remains the furthest behind the world's regions in terms of health improvements and longevity, as do its sub-Saharan African regions and societies specifically. This study documents: 1 theoretically and empirically the similarities and differences between the demographic transition, epidemiological transition, and health transition; 2 simple summary indicators that can be used to evaluate their descriptive and predictive features; 3 marked disparities in the onset and pace of variations and divergent trends in health, disease, and mortality patterns as well as fertility and life expectancy trajectories among African countries and regions over the past 60 years; 4 the rapid decline in infant
Non-marital pregnancy and the second demographic transition in Australia in historical perspective
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Gordon Carmichael
2014-03-01
Full Text Available Background: Australia has remarkably detailed data on non-marital pregnancy dating from 1908. They both offer insight into long-term trends in childbearing resulting from non-marital sexual activity and reveal in historical context key features of the second demographic transition and its genesis. Objective: Trends are traced in rates of non-marital conception of children ultimately born both outside and within marriage. A range of related indices is also presented in examining how demographic behaviour surrounding non-marital pregnancy (i helped generate the second demographic transition and (ii unfolded as a component of it. Methods: Core indices are rates of non-marital conception partitioned into additive components associated with marital and non-marital confinement. Data on non-marital and early marital births (at marriage durations 0-7 months are lagged back 38 weeks to a date of and age at conception basis to facilitate a common, unmarried, population at risk. Results: Post-war weakening of parental oversight of courtship was a fundamental trigger to the broader rejection of normative and institutional values that underpinned the second demographic transition. In tandem with denying the unmarried access to oral contraception it generated rampant youthful non-marital pregnancy, which undermined Judeo-Christian values, especially once abortion law reform occurred. Conclusions: Childbearing following non-marital conception transitioned rapidly after the 1960s from primarily the unintended product of youthful intercourse in non-coresidential relationships to mainly intended behaviour at normative reproductive ages in consensual unions. Family formation increasingly mixed non-marital births and premaritally and/or maritally conceived marital births.
Transition operators in electromagnetic-wave diffraction theory - General theory
Hahne, G. E.
1992-01-01
A formal theory is developed for the scattering of time-harmonic electromagnetic waves from impenetrable immobile obstacles with given linear, homogeneous, and generally nonlocal boundary conditions of Leontovich (impedance) type for the wave of the obstacle's surface. The theory is modeled on the complete Green's function and the transition (T) operator in time-independent formal scattering theory of nonrelativistic quantum mechanics. An expression for the differential scattering cross section for plane electromagnetic waves is derived in terms of certain matrix elements of the T operator for the obstacle.
Semiclassical transition in \\phi^4 theory
Kyatkin, A B
1994-01-01
We have shown an example of semiclassical transition in $\\phi^{4}$ theory with positive coupling constant. This process can be described by the classical $O(4)$-invariant solution, considered on a contour in the complex time plane. The transition is technically analogous to the one-instanton transition in the electroweak model. It is suppressed by the factor $\\exp(-2S_{0})$, where $S_{0}$ is Lipatov instanton action. This process describes a semiclassical transition between two coherent states with much smaller number of particles in the initial state than in the final state. Therefore, it could be relevant to the problem of calculation of amplitudes for multiparticle production in $\\phi^4$-type models.
Hyperconifold transitions, mirror symmetry, and string theory
Energy Technology Data Exchange (ETDEWEB)
Davies, Rhys, E-mail: daviesr@maths.ox.ac.uk [Mathematical Institute, University of Oxford, 24-29 St Giles, Oxford OX1 3LB (United Kingdom)
2011-09-01
Multiply-connected Calabi-Yau threefolds are of particular interest for both string theorists and mathematicians. Recently it was pointed out that one of the generic degenerations of these spaces (occurring at codimension one in moduli space) is an isolated singularity which is a finite cyclic quotient of the conifold; these were called hyperconifolds. It was also shown that if the order of the quotient group is even, such singular varieties have projective crepant resolutions, which are therefore smooth Calabi-Yau manifolds. The resulting topological transitions were called hyperconifold transitions, and change the fundamental group as well as the Hodge numbers. Here Batyrev's construction of Calabi-Yau hypersurfaces in toric fourfolds is used to demonstrate that certain compact examples containing the remaining hyperconifolds - the Z{sub 3} and Z{sub 5} cases - also have Calabi-Yau resolutions. The mirrors of the resulting transitions are studied and it is found, surprisingly, that they are ordinary conifold transitions. These are the first examples of conifold transitions with mirrors which are more exotic extremal transitions. The new hyperconifold transitions are also used to construct a small number of new Calabi-Yau manifolds, with small Hodge numbers and fundamental group Z{sub 3} or Z{sub 5}. Finally, it is demonstrated that a hyperconifold is a physically sensible background in Type IIB string theory. In analogy to the conifold case, non-perturbative dynamics smooth the physical moduli space, such that hyperconifold transitions correspond to non-singular processes in the full theory.
On the dynamics of the world demographic transition and financial-economic crises forecasts
Akaev, A.; Sadovnichy, V.; Korotayev, A.
2012-05-01
The article considers dynamic processes involving non-linear power-law behavior in such apparently diverse spheres, as demographic dynamics and dynamics of prices of highly liquid commodities such as oil and gold. All the respective variables exhibit features of explosive growth containing precursors indicating approaching phase transitions/catastrophes/crises. The first part of the article analyzes mathematical models of demographic dynamics that describe various scenarios of demographic development in the post-phase-transition period, including a model that takes the limitedness of the Earth carrying capacity into account. This model points to a critical point in the early 2050s, when the world population, after reaching its maximum value may decrease afterward stabilizing then at a certain stationary level. The article presents an analysis of the influence of the demographic transition (directly connected with the hyperexponential growth of the world population) on the global socioeconomic and geopolitical development. The second part deals with the phenomenon of explosive growth of prices of such highly liquid commodities as oil and gold. It is demonstrated that at present the respective processes could be regarded as precursors of waves of the global financial-economic crisis that will demand the change of the current global economic and political system. It is also shown that the moments of the start of the first and second waves of the current global crisis could have been forecasted with a model of accelerating log-periodic fluctuations superimposed over a power-law trend with a finite singularity developed by Didier Sornette and collaborators. With respect to the oil prices, it is shown that it was possible to forecast the 2008 crisis with a precision up to a month already in 2007. The gold price dynamics was used to calculate the possible time of the start of the second wave of the global crisis (July-August 2011); note that this forecast has turned out
Detecting the Evolution of Deliberate Fertility Control before the Demographic Transition in Germany
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Aliaksandr Amialchuk
2012-10-01
Full Text Available BACKGROUND Pervious literature has established the existence of deliberate non-parity-specific fertility control in pre-transitional populations. However, less focus has been given to the timing of its onset. In addition, previous studies focused on the changes in fertility in response to the local prices of grains, which may be endogenous. OBJECTIVE This paper studies the emergence and evolution of deliberate fertility control by investigating the link between child mortality and economic stress on the one hand and non-parity-specific birth control on the other, in historic German villages between 1700 and 1900. METHODS Birth histories from fourteen German villages (1700-1900 and rye price series are used in a micro-level event history analysis. The fertility response of second and higher-order births to the mortality of children over age two and exogenous fluctuations in rye price are used as measures of the extent of deliberate non-parity-specific birth control. RESULTS Over the course of the demographic transition, the effect of the death of children generally increases after controlling for the effect of the death of children less than two years old. The negative fertility response to high rye prices before and in the year immediately following the price change occurred only after 1800. CONCLUSIONS The replacement and insurance effects associated with child mortality generally increased before the demographic transition. The emergence of the negative effect of high rye prices on fertility after 1800 further supports the presence and evolution of deliberate non-parity-specific fertility control before the demographic transition.
Chiral phase transition from string theory.
Parnachev, Andrei; Sahakyan, David A
2006-09-15
The low energy dynamics of a certain D-brane configuration in string theory is described at weak t'Hooft coupling by a nonlocal version of the Nambu-Jona-Lasinio model. We study this system at finite temperature and strong t'Hooft coupling, using the string theory dual. We show that for sufficiently low temperatures chiral symmetry is broken, while for temperatures larger then the critical value, it gets restored. We compute the latent heat and observe that the phase transition is of the first order.
Melonic phase transition in group field theory
Baratin, Aristide; Oriti, Daniele; Ryan, James P; Smerlak, Matteo
2013-01-01
Group field theories have recently been shown to admit a 1/N expansion dominated by so-called `melonic graphs', dual to triangulated spheres. In this note, we deepen the analysis of this melonic sector. We obtain a combinatorial formula for the melonic amplitudes in terms of a graph polynomial related to a higher dimensional generalization of the Kirchhoff tree-matrix theorem. Simple bounds on these amplitudes show the existence of a phase transition driven by melonic interaction processes. We restrict our study to the Boulatov-Ooguri models, which describe topological BF theories and are the basis for the construction of four dimensional models of quantum gravity.
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Sean S Downey
Full Text Available Analysis of the proportion of immature skeletons recovered from European prehistoric cemeteries has shown that the transition to agriculture after 9000 BP triggered a long-term increase in human fertility. Here we compare the largest analysis of European cemeteries to date with an independent line of evidence, the summed calibrated date probability distribution of radiocarbon dates (SCDPD from archaeological sites. Our cemetery reanalysis confirms increased growth rates after the introduction of agriculture; the radiocarbon analysis also shows this pattern, and a significant correlation between both lines of evidence confirms the demographic validity of SCDPDs. We analyze the areal extent of Neolithic enclosures and demographic data from ethnographically known farming and foraging societies and we estimate differences in population levels at individual sites. We find little effect on the overall shape and precision of the SCDPD and we observe a small increase in the correlation with the cemetery trends. The SCDPD analysis supports the hypothesis that the transition to agriculture dramatically increased demographic growth, but it was followed within centuries by a general pattern of collapse even after accounting for higher settlement densities during the Neolithic. The study supports the unique contribution of SCDPDs as a valid demographic proxy for the demographic patterns associated with early agriculture.
The New Demographic Transition: Most Gains in Life Expectancy Now Realized Late in Life
Eggleston, Karen N.; Fuchs, Victor R.
2013-01-01
The share of increases in life expectancy realized after age 65 was only about 20 percent at the beginning of the 20th century for the US and 16 other countries at comparable stages of development; but that share was close to 80 percent by the dawn of the 21st century, and is almost certainly approaching 100 percent asymptotically. This new demographic transition portends a diminished survival effect on working life. For high-income countries at the forefront of the longevity transition, expected lifetime labor force participation as a percent of life expectancy is declining. Innovative policies are needed if societies wish to preserve a positive relationship running from increasing longevity to greater prosperity. PMID:25076810
Demographic transition and the dynamics of measles in six provinces in China: A modeling study.
Li, Sheng; Ma, Chao; Hao, Lixin; Su, Qiru; An, Zhijie; Ma, Fubao; Xie, Shuyun; Xu, Aiqiang; Zhang, Yanyang; Ding, Zhengrong; Li, Hui; Cairns, Lisa; Wang, Huaqing; Luo, Huiming; Wang, Ning; Li, Li; Ferrari, Matthew J
2017-04-01
Industrialization and demographic transition generate nonstationary dynamics in human populations that can affect the transmission and persistence of infectious diseases. Decades of increasing vaccination and development have led to dramatic declines in the global burden of measles, but the virus remains persistent in much of the world. Here we show that a combination of demographic transition, as a result of declining birth rates, and reduced measles prevalence, due to improved vaccination, has shifted the age distribution of susceptibility to measles throughout China. We fit a novel time-varying catalytic model to three decades of age-specific measles case reporting in six provinces in China to quantify the change in the age-specific force of infection for measles virus over time. We further quantified the impact of supplemental vaccination campaigns on the reduction of susceptible individuals. The force of infection of measles has declined dramatically (90%-97% reduction in transmission rate) in three industrialized eastern provinces during the last decade, driving a concomitant increase in both the relative proportion and absolute number of adult cases, while three central and western provinces exhibited dynamics consistent with endemic persistence (24%-73% reduction in transmission rate). The reduction in susceptible individuals due to supplemental vaccination campaigns is frequently below the nominal campaign coverage, likely because campaigns necessarily vaccinate those who may already be immune. The impact of these campaigns has significantly improved over time: campaigns prior to 2005 were estimated to have achieved less than 50% reductions in the proportion susceptible in the target age classes, but campaigns from 2005 onwards reduced the susceptible proportion by 32%-87%. A limitation of this study is that it relies on case surveillance, and thus inference may be biased by age-specific variation in measles reporting. The age distribution of measles cases
Increase in Preterm Birth during Demographic Transition in Chile from 1991 to 2012
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Paulina López Orellana
2015-01-01
Full Text Available Introduction. Universally mothers at 35 years or more have had higher maternal and perinatal risks. This study analyzed the trend of this group in maternal population and determined their risk of having premature children, during the demographic transition period in Chile. Materials and Methods. Epidemiological study conducted in the population of simple live births registered in the Chilean National Database Births of 1991–2012. Analyses were performed in three categories of maternal age: 35 or more, under 35, and 20 to 29 years. The risk of prematurity was measured by crude and Adjusted Odds Ratio from logistic regression model. Results. Mothers aged 35 and older increased in population from 10.6% in 1991 to 16.7% in 2012 and presented an overall prevalence of preterm delivery of 6.7%, higher prevalence than 20–29 age group (4.7%. In aging mothers, the Odds Ratio for preterm birth adjusted for education, marital status, and parity was 1.68 (95% CI (1.66–1.70 compared to mothers aged 20–29. All differences were significant (p<0.001. Conclusions. During Chilean demographic transition, mothers aged 35 or older increased steadily and significantly maintaining higher risks of preterm births. Policies to prevent and monitor the late motherhood could contribute to stopping the current trend.
Increase in Preterm Birth during Demographic Transition in Chile from 1991 to 2012
López Orellana, Paulina
2015-01-01
Introduction. Universally mothers at 35 years or more have had higher maternal and perinatal risks. This study analyzed the trend of this group in maternal population and determined their risk of having premature children, during the demographic transition period in Chile. Materials and Methods. Epidemiological study conducted in the population of simple live births registered in the Chilean National Database Births of 1991–2012. Analyses were performed in three categories of maternal age: 35 or more, under 35, and 20 to 29 years. The risk of prematurity was measured by crude and Adjusted Odds Ratio from logistic regression model. Results. Mothers aged 35 and older increased in population from 10.6% in 1991 to 16.7% in 2012 and presented an overall prevalence of preterm delivery of 6.7%, higher prevalence than 20–29 age group (4.7%). In aging mothers, the Odds Ratio for preterm birth adjusted for education, marital status, and parity was 1.68 (95% CI (1.66–1.70)) compared to mothers aged 20–29. All differences were significant (p < 0.001). Conclusions. During Chilean demographic transition, mothers aged 35 or older increased steadily and significantly maintaining higher risks of preterm births. Policies to prevent and monitor the late motherhood could contribute to stopping the current trend. PMID:26413549
Mini, G K
2009-07-01
Kerala State in India is the most advanced in terms of demographic and epidemiological transition and has the highest proportion of elderly population. The study examines the socio-demographic correlates of health status of elderly persons in Kerala in terms of three components: perceived health status, physical mobility and morbidity level. Overall health status was measured by combining the above three components of health status. Data from the 60th National Sample Survey Organization (NSSO) on Condition and Health Care of the Aged in Kerala in 2004 was used for the study. Significant socio-demographic differentials in health status were noted. While women report less morbidity, perceived well-being and physical mobility was better for men. This anomaly can be explained by variations in the components of socio-demographic factors. The findings call for urgent health care strategies for elderly persons in different socio-demographic groups in transitional Indian states like Kerala.
Unified Gauge Field Theory and Topological Transitions
Patwardhan, A
2004-01-01
The search for a Unified description of all interactions has created many developments of mathematics and physics. The role of geometric effects in the Quantum Theory of particles and fields and spacetime has been an active topic of research. This paper attempts to obtain the conditions for a Unified Gauge Field Theory, including gravity. In the Yang Mills type of theories with compactifications from a 10 or 11 dimensional space to a spacetime of 4 dimensions, the Kaluza Klein and the Holonomy approach has been used. In the compactifications of Calabi Yau spaces and sub manifolds, the Euler number Topological Index is used to label the allowed states and the transitions. With a SU(2) or SL(2,C) connection for gravity and the U(1)*SU(2)*SU(3) or SU(5) gauge connection for the other interactions, a Unified gauge field theory is expressed in the 10 or 11 dimension space. Partition functions for the sum over all possible configurations of sub spaces labeled by the Euler number index and the Action for gauge and m...
The role or structural criteria in transition theory
Jagers op Akkerhuis, Gerard A.J.M.
2016-01-01
In a recent publication Szathmáry has updated Major Evolutionary Transitions theory to a version 2.0. The major transition theory recognises transitions based on the select use of functional criteria, notably: cooperation, competition reduction and reproduction as part of a larger unit. These
Reher, David Sven; Sandström, Glenn; Sanz-Gimeno, Alberto; van Poppel, Frans W A
2017-02-01
We use a set of linked reproductive histories taken from Sweden, the Netherlands, and Spain for the period 1871-1960 to address key issues regarding how reproductive change was linked specifically to mortality and survivorship and more generally to individual agency. Using event-history analysis, this study investigates how the propensity to have additional children was influenced by the number of surviving offspring when reproductive decisions were made. The results suggest that couples were continuously regulating their fertility to achieve reproductive goals. Families experiencing child fatalities show significant increases in the hazard of additional births. In addition, the sex composition of the surviving sibset also appears to have influenced reproductive decisions in a significant but changing way. The findings offer strong proof of active decision-making during the demographic transition and provide an important contribution to the literature on the role of mortality for reproductive change.
Fehren-Schmitz, Lars; Haak, Wolfgang; Mächtle, Bertil; Masch, Florian; Llamas, Bastien; Cagigao, Elsa Tomasto; Sossna, Volker; Schittek, Karsten; Isla Cuadrado, Johny; Eitel, Bernhard; Reindel, Markus
2014-07-01
Several archaeological studies in the Central Andes have pointed at the temporal coincidence of climatic fluctuations (both long- and short-term) and episodes of cultural transition and changes of socioeconomic structures throughout the pre-Columbian period. Although most scholars explain the connection between environmental and cultural changes by the impact of climatic alterations on the capacities of the ecosystems inhabited by pre-Columbian cultures, direct evidence for assumed demographic consequences is missing so far. In this study, we address directly the impact of climatic changes on the spatial population dynamics of the Central Andes. We use a large dataset of pre-Columbian mitochondrial DNA sequences from the northern Rio Grande de Nasca drainage (RGND) in southern Peru, dating from ∼840 BC to 1450 AD. Alternative demographic scenarios are tested using Bayesian serial coalescent simulations in an approximate Bayesian computational framework. Our results indicate migrations from the lower coastal valleys of southern Peru into the Andean highlands coincident with increasing climate variability at the end of the Nasca culture at ∼640 AD. We also find support for a back-migration from the highlands to the coast coincident with droughts in the southeastern Andean highlands and improvement of climatic conditions on the coast after the decline of the Wari and Tiwanaku empires (∼1200 AD), leading to a genetic homogenization in the RGND and probably southern Peru as a whole.
Dimensions of Rational Decision-Making during the Demographic Transition; Aranjuez (Spain Revisited
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David Reher
2015-03-01
Full Text Available A set of linked reproductive histories taken from the Spanish town of Aranjuez during the demographic transition is used to address key issues regarding reproductive change and reproductive choice. This paper builds on the existing literature and especially on the findings first shown in Reher & Sanz-Gimeno (2007 and in Van Poppel et al. (2012 where the links between childhood survival and reproductive decision-making were specified. This paper goes beyond the original ones in two important ways: (a the sex composition of the surviving sibset is included in the analysis and (b behavior is modeled by means of event history analysis. In these models, controls for the survival status of the previous child are introduced so as to distinguish between biological factors related to the cessation of breastfeeding and both short term (child replacement and more long-term reproductive strategies. The results offer convincing proof that couples were continually regulating their fertility in order to achieve reproductive goals both in terms of net fertility and of the sex composition of the resulting sibset. Here results show that both sexes were desired by parents but that lack of surviving males had greater influence on fertility behavior. As expected, controls for the survival status of the previous-born child were important though they did not diminish appreciably the overall effect of the number of surviving offspring. This article offers strong proof for the existence of active decision-making during the demographic transition and applies a method to model these behaviors over the full reproductive history of the couple.
Transitions theory: a trajectory of theoretical development in nursing.
Im, Eun-Ok
2011-01-01
There have been very few investigations into how any single nursing theory has actually evolved historically. In this paper, a trajectory of theoretical development in nursing is explored through reviewing the theoretical development of a single nursing theory-transitions theory. The literature related to transitions theory was searched and retrieved using multiple databases. Ninety-nine papers were analyzed according to type of theory, populations of interest, sources of theorizing, and theoretical methods. Transitions theory originated in research but was initially borrowed. It also arose in research with immigrants and from national and international collaborative research efforts. A product of mentoring, transitions theory is used widely in nursing education, research, and practice. Diverse thoughts related to transitions theory coexist. For future theoretical development in nursing, we need to remain open to new ideas and continue to engage in multiple collaborative efforts.
Keynes’ monetary theory and transition economies
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Ivan Ribnikar
2007-05-01
Full Text Available After a short outline of how Keynes’ monetary theory was being accepted, read and discussed before the transition period started at early 1990s, two key issues somehow connected with Keynes are being analyzed in this paper. The first issue focuses on the problems of selling of business enterprises, i.e.their shares, in transition countries, as they had to be transformed from stately or socially owned to privately owned companies. These problems are remotely similar to problems resolved or ‘resolved’ by the Say’s Law. If the government does not enable private sector to buy companies, domestic savings and capital formation will decrease. For instance, what the government should have done in cases where businessenterprises were socially owned is being analyzed and illustrated with IS-LM diagrams for the open economy. The second issue deals with how the central bank should behave – especially if the government had not done anything to enable smooth purchases of business enterprises by the domestic private sectors. The central bank should prevent either monetary expansion or appreciation of thedomestic currency by sterilized purchases of the surpluses of foreign currencies on the foreign exchange market. Both issues are somehow connected with Keynes and/or economists whether either his followers or not.
Situation-specific theories from the middle-range transitions theory.
Im, Eun-Ok
2014-01-01
The purpose of this article was to analyze the theory development process of the situation-specific theories that were derived from the middle-range transitions theory. This analysis aims to provide directions for future development of situation-specific theories. First, transitions theory is concisely described with its history, goal, and major concepts. Then, the approach that was used to retrieve the situation-specific theories derived from transitions theory is described. Next, an analysis of 6 situation-specific theories is presented. Finally, 4 themes reflecting commonalities and variances in the theory development process are discussed with implications for future theoretical development.
Modified Transition State Theory for Evaporation and Condensation
Institute of Scientific and Technical Information of China (English)
王遵敬; 陈民; 过增元
2002-01-01
A modification of the transition state theory for evaporation and condensation is presented by analysing the kinetic characteristics of liquid-vapour interphase transport. In the modified transition state theory, the moving orientation of molecules is introduced into the calculation of the free volume of the activated complex. The condensation coefficients of argon at different temperatures are calculated with the modified transition state theory. The results agree well with those from molecular dynamics simulations.
Kertzer, David I; White, Michael J; Bernardi, Laura; Gabrielli, Giuseppe
2009-02-01
The deep drop of the fertility rate in Italy to among the lowest in the world challenges contemporary theories of childbearing and family building. Among high-income countries, Italy was presumed to have characteristics of family values and female labor force participation that would favor higher fertility than its European neighbors to the north. We test competing economic and cultural explanations, drawing on new nationally representative, longitudinal data to examine first union, first birth, and second birth. Our event history analysis finds some support for economic determinants of family formation and fertility, but the clear importance of regional differences and of secularization suggests that such an explanation is at best incomplete and that cultural and ideational factors must be considered.
Hyska, Jolanda; Mersini, Ehadu; Mone, Iris; Burazeri, Genc
2014-10-01
Our aim was to assess the prevalence and demographic correlates of overweight and obesity among children in Albania, a transitional country in Southeastern Europe. A nationwide survey was conducted in Albania in 2013 including a representative sample of 5,810 schoolchildren aged 7.0-9.9 years (51.5 % boys aged 8.5 ± 0.6 years and 49.5 % girls aged 8.4 ± 0.6 years; overall response: 97 %). All children were measured height and weight, based on which the body mass index (BMI) was calculated. The criteria of the World Health Organization (WHO) and the International Obesity Task Force (IOTF) were used to describe the distribution of BMI among children. Overall, mean value of BMI was 16.4 ± 2.4 (16.7 ± 2.5 in boys vs. 16.2 ± 2.4 in girls, P < 0.001). As per WHO criteria, 9.8 % of the boys were obese versus 5.5 % of the girls (P < 0.001). The prevalence of both overweight and obesity were remarkably higher among urban children compared with their rural counterparts (17.9 vs. 10.5 and 11.9 vs. 4.0 %, respectively, P < 0.001). As per IOTF criteria, 3.8 % of the boys were obese compared with 2.8 % of the girls (P < 0.001). The prevalence of overweight and obesity were similarly higher among urban children than in rural children (15.6 vs. 7.3 and 5.5 vs. 1.4 %, respectively, P < 0.001). Our findings indicate that Albania is in the middle of nutritional transition with a high prevalence of overweight and obesity among children aged 7.0-9.9 years. This is particularly evident in urban areas of the country. Conversely, our data do not indicate a double burden of malnutrition among children in Albania.
A Quantum Version of Wigner's Transition State Theory
Schubert, R.; Waalkens, H.; Wiggins, S.
2009-01-01
A quantum version of a recent realization of Wigner's transition state theory in phase space is presented. The theory developed builds on a quantum normal form which locally decouples the quantum dynamics near the transition state to any desired order in (h) over bar. This leads to an explicit algor
A Quantum Version of Wigner’s Transition State Theory
Schubert, R.; Waalkens, H.; Wiggins, S.
2009-01-01
A quantum version of a recent realization of Wigner’s transition state theory in phase space is presented. The theory developed builds on a quantum normal form which locally decouples the quantum dynamics near the transition state to any desired order in ħ. This leads to an explicit algorithm to com
The role of structural criteria in transitions theory
Jagers op Akkerhuis, Gerard A.J.M.
2016-01-01
The Major Evolutionary Transitions theory of Szathmáry and Maynard Smith is famous for its contribution to the understanding of complex wholes in biology. Typical for Major Evolutionary Transitions theory is the select use of functional criteria, notably, cooperation, competition reduction and re
The neolithic demographic transition and oral health: The Southeast Asian experience.
Willis, Anna; Oxenham, Marc F
2013-10-01
The purpose of this article is to present new oral health data from Neolithic An Son, southern Vietnam, in the context of (1) a reassessment of published data on other Neolithic, Bronze, and Iron Age Southeast Asian dental series, and (2) predictions of the Neolithic Demographic Transition (NDT). To this end, frequencies for three oral conditions (caries, antemortem tooth loss, and alveolar lesions) were investigated for seven Southeast Asian adult dental series from Thailand and Vietnam with respect to time period, age-at-death and sex. A clear pattern of elevated rates for oral disease in the Neolithic followed by a marked improvement in oral health during the Bronze and Iron Ages was observed. Moreover, rates of caries and antemortem tooth loss for females were almost without exception higher than that for males in all samples. The consensus view among Southeast Asian bioarchaeologists that oral health did not decline with the adoption/intensification of agriculture in Southeast Asia, can no longer be supported. In light of evidence for (1) the low cariogenicity of rice; (2) the physiological predisposition of females (particularly when pregnant) to poorer oral health; and (3) health predictions of the NDT model with respect to elevated levels of fertility, the most plausible chief explanation for the observed patterns in oral health in Southeast Asia is increased levels of fertility during the Neolithic, followed by a decline in fertility during the subsequent Bronze and Iron Ages.
Landau Theory in the Region of First Order Phase Transitions
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O.G. Medvedovskaya
2014-04-01
Full Text Available For the case when the line of the first order phase transitions does not transform into the line of the second order phase transitions, i.e. not as ends with the tricritical point but not with a critical one: critical lines, limiting the region of metastable states, by using the Landau theory of phase transitions were determined.
How Theories of Organization Inform Transition Studies
van Mossel, Allard; van Rijnsoever, Frank; Hekkert, Marko
2014-01-01
In historical socio-technical transitions, organizations functioned as the principal drivers of transitions, invented the defining innovations, and created the cognitive and normative rules that led industries to embrace the innovation and associated behavior. Yet, despite their importance, the roles of organizations in transitions and, in particular, the processes that guide and coordinate their behavior, remain under-conceptualized in some transition frameworks, including the Multi-Level Pe...
How Theories of Organization Inform Transition Studies
van Mossel, Allard; van Rijnsoever, Frank; Hekkert, Marko
2014-01-01
In historical socio-technical transitions, organizations functioned as the principal drivers of transitions, invented the defining innovations, and created the cognitive and normative rules that led industries to embrace the innovation and associated behavior. Yet, despite their importance, the role
Directory of Open Access Journals (Sweden)
Elina Mäenpää
2008-12-01
Full Text Available The article studies to what extent regional socioeconomic and cultural characteristics explain spatial patterns in the Second Demographic Transition in Finland. The country's 75 functional regions are used as area units. A summary indicator of the transition based on divorce and cohabitation is used as the dependent variable. The results show that the spatial pattern is mainly determined according to the regional level of urbanization, but the effect is mediated by cultural characteristics (secularization and support for the socialist and green parties. The cultural characteristics have only a modest independent effect.
Quantum Theory of Hyperfine Structure Transitions in Diatomic Molecules.
Klempt, E.; And Others
1979-01-01
Described is an advanced undergraduate laboratory experiment in which radio-frequency transitions between molecular hyperfine structure states may be observed. Aspects of the quantum theory applied to the analysis of this physical system, are discussed. (Authors/BT)
Transition state theory and the dynamics of hard disks.
Barnett-Jones, M; Dickinson, P A; Godfrey, M J; Grundy, T; Moore, M A
2013-11-01
The dynamics of two- and five-disk systems confined in a square has been studied using molecular dynamics simulations and compared with the predictions of transition state theory. We determine the partition functions Z and Z(‡) of transition state theory using a procedure first used by Salsburg and Wood for the pressure. Our simulations show this procedure and transition state theory are in excellent agreement with the simulations. A generalization of the transition state theory to the case of a large number of disks N is made and shown to be in full agreement with simulations of disks moving in a narrow channel. The same procedure for hard spheres in three dimensions leads to the Vogel-Fulcher-Tammann formula for their alpha relaxation time.
Theory of Microcrediting in Transitional Economies
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Nikola Kadoić
2009-06-01
Full Text Available In the early 1970s, Bangladeshi banker and economist Dr. Muhammad Yunus designed microcrediting – a socially sensitive and rightful system of fighting poverty and high unemployment rates. His Grameen Bank for the poorest of the poor in Bangladesh has so far lifted more than 3.2 million of individuals and their families out of poverty. After initial successes at home, microcredit was put into service for reducing unemployment and alleviating poverty in numerous countries throughout the world. This paper explores specific problems that a typical transitional country (like Croatia, is likely to face, with unemployment – the source of a vast number of related problems in a transitional society – as the focal point. The authors have attempted to incorporate particularities of a transitional economy into the original microcrediting principles. As a solution to problems afflicting the domestic economy, the authors define a global microcrediting system framework on the macroeconomic level, assuming at the same time that microcrediting of socially vulnerable groups can resolve many problems of modern transitional societies. Arising from the authors' primary intention – to consider in depth the functionality of microcrediting in general transition conditions – a transitional microcrediting system has been defined in general terms, and a corresponding financial and mathematical model developed.
Queueing phase transition: theory of translation.
Romano, M Carmen; Thiel, Marco; Stansfield, Ian; Grebogi, Celso
2009-05-15
We study the current of particles on a lattice, where to each site a different hopping probability has been associated and the particles can move only in one direction. We show that the queueing of the particles behind a slow site can lead to a first-order phase transition, and derive analytical expressions for the configuration of slow sites for this to happen. We apply this stochastic model to describe the translation of mRNAs. We show that the first-order phase transition, uncovered in this work, is the process responsible for the classification of the proteins having different biological functions.
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Frans Van Poppel
2012-08-01
Full Text Available BACKGROUND According to classic demographic transition theory, mortality change is the key factor that triggers a decline in fertility. Research on this topic has mostly relied on aggregate or time series data. Since fertility is based on the joint decisions of couples when confronted with specific fertility-childhood mortality outcomes, a focus on the experiences of individual couples is needed. Recently, Reher and Sanz-Gimeno used this approach to analyze individual longitudinal data for the Spanish town of Aranjuez. OBJECTIVE We investigate whether, in a country and in populations characterized by varying cultural and socioeconomic circumstances, family organization, and demographic regimes, the same mechanisms influenced the process of fertility decline as in Spain. METHODS The study uses micro longitudinal data from the Historical Sample of the Netherlands for a period stretching from the last quarter of the 19th century to the middle of the 20th century, and demographic measures identical to those used in the Spanish study to test whether the decline in fertility was triggered by the decline in mortality at the level of the family. As religious groups and social classes differed in their ability to correctly assess the implications of mortality levels, and in their willingness, readiness, and ability to react to these changes by adapting their reproductive behavior, we also compared the effect of mortality decline by the religion and the social class of the couples. RESULTS We observed that childhood survival had clear effects on reproduction, the chances of having another child, and the length of the intervals between births, which indicates that this variable was crucial for fertility decisions. This pattern was especially strong after 1900. There were rather consistent and expected differences in the reactions to the survival of children by social class and religious group. Whereas skilled workers were rather sensitive to the number of
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Petrović Mina
2011-01-01
Full Text Available The paper starts by questioning the theory of second demographic transition (SDT and its universal relevance in the field of marriage behavior and family organization in low fertility context, arguing for more differentiated approaches. With an aim to illustrate the contextual specifics of post-socialist countries in general and of Serbia in particular, the author claims that analyzed changes have not just been delayed or incomplete in comparison to more developed European countries, but shaped by specific modernization processes, which led to rationally developed strategies in overcoming structural risks, although, without ideational changes typical to the theory of SDT. Slow changes in marital behavior and family organization in Serbia are illustrated in recent sociological (empirical research findings. The perceived changes are linked to specific structural risks (war, slow transformation and enduring economic hardships, weak state and low trust in institutions, etc and value characteristics (persistence of materialism and traditionalism, but with increasing ambivalence. The connection between structural and ideational changes is considered through social stratification variable by relying on Coale's model on necessary preconditions for behavioral changes as well as on social deprivation concept. Having in mind upper social strata (more educated and better off, the value changes precede the behavioral that are adapted to economic uncertainty, which still force more traditional marital and family patterns. Therefore, there is a rank of different options, from extended family (for a short period at the beginning of marriage or after divorce to separated leaving (of married partners in parental households (due to refusing the extended family option thus creating quite specific "living apart together" form, combined with dominant strategy of prolonging the marriage. Hence, for upper social strata, marriage is still a universal but negotiable
Diasporas and transitions in Actor-Network Theory
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Blanca Callén
2011-03-01
Full Text Available This paper is an introduction to the monograph titled Diasporas and Transitions in the Actor-Network Theory. Drawing a parallel with ethnomethodology, its pages present the main features of this theory, a way to figure out its origins and a description of its present. The text ends with a brief look at the state of art of actor-network theory in Spain and an appraisal of a meeting titled Present and Future of Actor-Network Theory, which is the origin of our monograph. In this paper we put forward a very simple idea: Actor-Network Theory was born with certain relevance in Social Sciences when it diffracted in a myriad of different uses and applications. The main corollary of such an idea is also straightforward: the very difference between Actor-Network Theory and other perspectives in Social Sciences resides in the permanent diaspora and transition of the former.
Explore Stochastic Instabilities of Periodic Points by Transition Path Theory
Cao, Yu; Lin, Ling; Zhou, Xiang
2016-06-01
We consider the noise-induced transitions from a linearly stable periodic orbit consisting of T periodic points in randomly perturbed discrete logistic map. Traditional large deviation theory and asymptotic analysis at small noise limit cannot distinguish the quantitative difference in noise-induced stochastic instabilities among the T periodic points. To attack this problem, we generalize the transition path theory to the discrete-time continuous-space stochastic process. In our first criterion to quantify the relative instability among T periodic points, we use the distribution of the last passage location related to the transitions from the whole periodic orbit to a prescribed disjoint set. This distribution is related to individual contributions to the transition rate from each periodic points. The second criterion is based on the competency of the transition paths associated with each periodic point. Both criteria utilize the reactive probability current in the transition path theory. Our numerical results for the logistic map reveal the transition mechanism of escaping from the stable periodic orbit and identify which periodic point is more prone to lose stability so as to make successful transitions under random perturbations.
Confinement-Deconfinement transition in $SU(2)+$Higgs Theory
Biswal, Minati; Digal, Sanatan; Saumia, P S
2016-01-01
We study the confinement-deconfinement transition in $SU(2)$ gauge theory in the presence of massless bosons using lattice Monte Carlo simulations. The nature of this transition depends on the temporal extent ($N_\\tau$) of the Euclidean lattice. We find that the transition is a cross-over for $N_\\tau=2,4$ and second order with $3D$ Ising universality class for $N_\\tau=8$. Our results show that the second order transition is accompanied by realization of the $Z_2$ symmetry.
On the theory of phase transitions in polypeptides
DEFF Research Database (Denmark)
Yakubovich, Alexander V.; Solov'yov, Ilia; Greiner, Walter
2008-01-01
We suggest a theoretical method based on the statistical mechanics for treating the alpha-helix random coil transition in polypeptides. This process is considered as a first-order-like phase transition. The developed theory is free of model parameters and is based solely on fundamental physical...... principles. We apply the developed formalism for the description of thermodynamical properties of alanine polypeptides of different length. We analyze the essential thermodynamical properties of the system such as heat capacity, phase transition temperature and latent heat of the phase transition...
Deconfinement and the Hagedorn transition in string theory.
Chaudhuri, S
2001-03-05
We introduce a new definition of the thermal partition function in string theory. With this new definition, the thermal partition functions of all of the string theories obey thermal duality relations with self-dual Hagedorn temperature beta(2)(H) = 4pi(2)alpha('). A beta-->beta(2)(H)/beta transformation maps the type I theory into a new string theory (type I) with thermal D p-branes, spatial hypersurfaces supporting a p-dimensional finite temperature non-Abelian Higgs-gauge theory for p< or =9. We demonstrate a continuous phase transition in the behavior of the static heavy quark-antiquark potential for small separations r(2)(*)
Linking Complexity and Sustainability Theories: Implications for Modeling Sustainability Transitions
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Camaren Peter
2014-03-01
Full Text Available In this paper, we deploy a complexity theory as the foundation for integration of different theoretical approaches to sustainability and develop a rationale for a complexity-based framework for modeling transitions to sustainability. We propose a framework based on a comparison of complex systems’ properties that characterize the different theories that deal with transitions to sustainability. We argue that adopting a complexity theory based approach for modeling transitions requires going beyond deterministic frameworks; by adopting a probabilistic, integrative, inclusive and adaptive approach that can support transitions. We also illustrate how this complexity-based modeling framework can be implemented; i.e., how it can be used to select modeling techniques that address particular properties of complex systems that we need to understand in order to model transitions to sustainability. In doing so, we establish a complexity-based approach towards modeling sustainability transitions that caters for the broad range of complex systems’ properties that are required to model transitions to sustainability.
String theory, quantum phase transitions, and the emergent Fermi liquid.
Cubrović, Mihailo; Zaanen, Jan; Schalm, Koenraad
2009-07-24
A central problem in quantum condensed matter physics is the critical theory governing the zero-temperature quantum phase transition between strongly renormalized Fermi liquids as found in heavy fermion intermetallics and possibly in high-critical temperature superconductors. We found that the mathematics of string theory is capable of describing such fermionic quantum critical states. Using the anti-de Sitter/conformal field theory correspondence to relate fermionic quantum critical fields to a gravitational problem, we computed the spectral functions of fermions in the field theory. By increasing the fermion density away from the relativistic quantum critical point, a state emerges with all the features of the Fermi liquid.
Scaling theory of topological phase transitions
Chen, Wei
2016-02-01
Topologically ordered systems are characterized by topological invariants that are often calculated from the momentum space integration of a certain function that represents the curvature of the many-body state. The curvature function may be Berry curvature, Berry connection, or other quantities depending on the system. Akin to stretching a messy string to reveal the number of knots it contains, a scaling procedure is proposed for the curvature function in inversion symmetric systems, from which the topological phase transition can be identified from the flow of the driving energy parameters that control the topology (hopping, chemical potential, etc) under scaling. At an infinitesimal operation, one obtains the renormalization group (RG) equations for the driving energy parameters. A length scale defined from the curvature function near the gap-closing momentum is suggested to characterize the scale invariance at critical points and fixed points, and displays a universal critical behavior in a variety of systems examined.
Ab initio theory of helix <-> coil phase transition
DEFF Research Database (Denmark)
Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.
2008-01-01
on fundamental physical principles. It describes essential thermodynamical properties of the system such as heat capacity, the phase transition temperature and others from the analysis of the polypeptide potential energy surface calculated as a function of two dihedral angles, responsible for the polypeptide...... twisting. The suggested theory is general and with some modification can be applied for the description of phase transitions in other complex molecular systems (e.g. proteins, DNA, nanotubes, atomic clusters, fullerenes)....
Ab initio theory of helix <-> coil phase transition
DEFF Research Database (Denmark)
Yakubovich, Alexander V.; Solov'yov, Ilia; Solov'yov, Andrey V.
2008-01-01
In this paper, we suggest a theoretical method based on the statistical mechanics for treating the alpha-helix <-> random coil transition in alanine polypeptides. We consider this process as a first-order phase transition and develop a theory which is free of model parameters and is based solely ...... twisting. The suggested theory is general and with some modification can be applied for the description of phase transitions in other complex molecular systems (e.g. proteins, DNA, nanotubes, atomic clusters, fullerenes).......In this paper, we suggest a theoretical method based on the statistical mechanics for treating the alpha-helix random coil transition in alanine polypeptides. We consider this process as a first-order phase transition and develop a theory which is free of model parameters and is based solely...... on fundamental physical principles. It describes essential thermodynamical properties of the system such as heat capacity, the phase transition temperature and others from the analysis of the polypeptide potential energy surface calculated as a function of two dihedral angles, responsible for the polypeptide...
Transition matrices and orbitals from reduced density matrix theory
Energy Technology Data Exchange (ETDEWEB)
Etienne, Thibaud [Université de Lorraine – Nancy, Théorie-Modélisation-Simulation, SRSMC, Boulevard des Aiguillettes 54506, Vandoeuvre-lès-Nancy (France); CNRS, Théorie-Modélisation-Simulation, SRSMC, Boulevard des Aiguillettes 54506, Vandoeuvre-lès-Nancy (France); Unité de Chimie Physique Théorique et Structurale, Université de Namur, Rue de Bruxelles 61, 5000 Namur (Belgium)
2015-06-28
In this contribution, we report two different methodologies for characterizing the electronic structure reorganization occurring when a chromophore undergoes an electronic transition. For the first method, we start by setting the theoretical background necessary to the reinterpretation through simple tensor analysis of (i) the transition density matrix and (ii) the natural transition orbitals in the scope of reduced density matrix theory. This novel interpretation is made more clear thanks to a short compendium of the one-particle reduced density matrix theory in a Fock space. The formalism is further applied to two different classes of excited states calculation methods, both requiring a single-determinant reference, that express an excited state as a hole-particle mono-excited configurations expansion, to which particle-hole correlation is coupled (time-dependent Hartree-Fock/time-dependent density functional theory) or not (configuration interaction single/Tamm-Dancoff approximation). For the second methodology presented in this paper, we introduce a novel and complementary concept related to electronic transitions with the canonical transition density matrix and the canonical transition orbitals. Their expression actually reflects the electronic cloud polarisation in the orbital space with a decomposition based on the actual contribution of one-particle excitations from occupied canonical orbitals to virtual ones. This approach validates our novel interpretation of the transition density matrix elements in terms of the Euclidean norm of elementary transition vectors in a linear tensor space. A proper use of these new concepts leads to the conclusion that despite the different principles underlying their construction, they provide two equivalent excited states topological analyses. This connexion is evidenced through simple illustrations of (in)organic dyes electronic transitions analysis.
Transition matrices and orbitals from reduced density matrix theory
Etienne, Thibaud
2015-06-01
In this contribution, we report two different methodologies for characterizing the electronic structure reorganization occurring when a chromophore undergoes an electronic transition. For the first method, we start by setting the theoretical background necessary to the reinterpretation through simple tensor analysis of (i) the transition density matrix and (ii) the natural transition orbitals in the scope of reduced density matrix theory. This novel interpretation is made more clear thanks to a short compendium of the one-particle reduced density matrix theory in a Fock space. The formalism is further applied to two different classes of excited states calculation methods, both requiring a single-determinant reference, that express an excited state as a hole-particle mono-excited configurations expansion, to which particle-hole correlation is coupled (time-dependent Hartree-Fock/time-dependent density functional theory) or not (configuration interaction single/Tamm-Dancoff approximation). For the second methodology presented in this paper, we introduce a novel and complementary concept related to electronic transitions with the canonical transition density matrix and the canonical transition orbitals. Their expression actually reflects the electronic cloud polarisation in the orbital space with a decomposition based on the actual contribution of one-particle excitations from occupied canonical orbitals to virtual ones. This approach validates our novel interpretation of the transition density matrix elements in terms of the Euclidean norm of elementary transition vectors in a linear tensor space. A proper use of these new concepts leads to the conclusion that despite the different principles underlying their construction, they provide two equivalent excited states topological analyses. This connexion is evidenced through simple illustrations of (in)organic dyes electronic transitions analysis.
Transition matrices and orbitals from reduced density matrix theory.
Etienne, Thibaud
2015-06-28
In this contribution, we report two different methodologies for characterizing the electronic structure reorganization occurring when a chromophore undergoes an electronic transition. For the first method, we start by setting the theoretical background necessary to the reinterpretation through simple tensor analysis of (i) the transition density matrix and (ii) the natural transition orbitals in the scope of reduced density matrix theory. This novel interpretation is made more clear thanks to a short compendium of the one-particle reduced density matrix theory in a Fock space. The formalism is further applied to two different classes of excited states calculation methods, both requiring a single-determinant reference, that express an excited state as a hole-particle mono-excited configurations expansion, to which particle-hole correlation is coupled (time-dependent Hartree-Fock/time-dependent density functional theory) or not (configuration interaction single/Tamm-Dancoff approximation). For the second methodology presented in this paper, we introduce a novel and complementary concept related to electronic transitions with the canonical transition density matrix and the canonical transition orbitals. Their expression actually reflects the electronic cloud polarisation in the orbital space with a decomposition based on the actual contribution of one-particle excitations from occupied canonical orbitals to virtual ones. This approach validates our novel interpretation of the transition density matrix elements in terms of the Euclidean norm of elementary transition vectors in a linear tensor space. A proper use of these new concepts leads to the conclusion that despite the different principles underlying their construction, they provide two equivalent excited states topological analyses. This connexion is evidenced through simple illustrations of (in)organic dyes electronic transitions analysis.
Langevin dynamics of the deconfinement transition for pure gauge theory
Fraga, E S; Krein, G; Fraga, Eduardo S.; Mizher, Ana J\\'ulia; Krein, Gast\\~ao
2007-01-01
We investigate the effects of dissipation in the deconfinement transition for pure SU(2) and SU(3) gauge theories. Using an effective theory for the order parameter, we study its Langevin evolution numerically. Noise effects are included for the case of SU(2). We find that both dissipation and noise have dramatic effects on the spinodal decomposition of the order parameter and delay considerably its thermalization. For SU(3) the effects of dissipation are even larger than for SU(2).
Langevin dynamics of the deconfinement transition for pure gauge theory
Mizher, Ana Júlia; Fraga, Eduardo S.; Krein, Gastão Inácio [UNESP
2006-01-01
We investigate the effects of dissipation in the deconfinement transition for pure SU(2) and SU(3) gauge theories. Using an effective theory for the order parameter, we study its Langevin evolution numerically. Noise effects are included for the case of SU(2). We find that both dissipation and noise have dramatic effects on the spinodal decomposition of the order parameter and delay considerably its thermalization. For SU(3) the effects of dissipation are even larger than for SU(2).
Langevin dynamics of the deconfinement transition for pure gauge theory
Energy Technology Data Exchange (ETDEWEB)
Mizher, Ana Julia; Fraga, Eduardo S. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Fisica; Krein, Gastao [Universidade Estadual Paulista (UNESP), Sao Paulo, SP (Brazil). Inst. de Fisica Teorica
2007-06-15
We investigate the effects of dissipation in the deconfinement transition for pure SU(2) and SU(3) gauge theories. Using an effective theory for the order parameter, we study its Langevin evolution numerically. Noise effects are included for the case of SU(2). We find that both dissipation and noise have dramatic effects on the spinodal decomposition of the order parameter and delay considerably its thermalization. For SU(3) the effects of dissipation are even larger than for SU(2). (author)
Analogy between Landau theory of phase transitions and Lagrangian mechanics
Ribeiro Filho, A.; Tilley, D.R.; Žekš, B.
1984-01-01
Texto completo. Acesso restrito. p. 247–249 It is shown that the definition of a stable point in landau theory is different from that used in mechanics. The implications for numerical work on phase transitions for systems that have a Lffshitz invariant are discussed.
Feminist theory, African gender history and transitional justice
African Journals Online (AJOL)
relationship of feminism and feminist theory to the field of transitional justice .... notion that autonomous states come together to make agreements and are then .... across religious and ethnic lines in an attempt to force men to make peace. ... currently located: without access to law, judiciary or medical care – all the potential ...
Colón-Ramos, Uriyoán; Pérez-Cardona, Cynthia M; Monge-Rojas, Rafael
2013-11-01
To identify socio-demographic, behavioral, and health-related correlates of food preferences in Puerto Rico that will help determine Caribbean-region populations vulnerable to nutrition transition. Data from a cross-sectional study of a representative sample of 858 adults residing in the San Juan Metropolitan Area of Puerto Rico were analyzed. Multivariable ordinal logistic regressions were used to model the frequency of consumption of 1) fruits and vegetables, 2) tubers/starchy root vegetables, 3) fried foods, and 4) Western-style fast foods as a function of socio-demographic, behavioral, and health-related characteristics. Higher frequency of consumption of fruits and vegetables was associated with being physically active and older and having a medium to high level of education, whereas intake of tubers was associated with being older, having a low income, not using government insurance, and having elevated levels of triglycerides. Frequency of consumption of fast food was associated with younger age, higher income, 12-15 years of formal education, and a higher body mass index (BMI), whereas frequency of consumption of fried food was associated with being younger and male, not being a smoker, and having elevated levels of fasting blood glucose. The results indicate a nutrition transition in Puerto Rico with health consequences for the Caribbean region. The characteristics of this nutrition transition seem to be determined by income, education, and age, but may also be dictated by access to various food groups. These results set the stage for needed investigation of environmental and individual-level factors that could shape patterns in food consumption.
Classical theory of resonant transition radiation in multilayer structures.
Pardo, B; André, J M
2001-01-01
A rigorous classical electromagnetic theory of the transition radiation in finite and infinite multilayer structures is presented. It makes the standard results of thin-film optics, such as the matrix formalism, accountable; it allows thus an exact treatment of the propagation of the waves induced by the electron. This method is applied to the particular case of the periodic structures to treat the resonant transition radiation (RTR). It is noted that the present theory gives, in the hard x-ray domain, results previously published. The reason for this approach is to make the numerical calculations rigorous and easy. The numerical results of our theory are compared to experimental RTR data obtained recently by Yamada et al. [Phys. Rev. A 59, 3673 (1999)] with a nickel-carbon multilayer structure.
Directory of Open Access Journals (Sweden)
Ailiana Santosa
2013-05-01
Full Text Available Background: Epidemiological transition (ET theory, first postulated in 1971, has developed alongside changes in population structures over time. However, understandings of mortality transitions and associated epidemiological changes remain poorly defined for public health practitioners. Here, we review the concept and development of ET theory, contextualising this in empirical evidence, which variously supports and contradicts the original theoretical propositions. Design: A Medline literature search covering publications over four decades, from 1971 to 2013, was conducted. Studies were included if they assessed human populations, were original articles, focused on mortality and health or demographic or ET and were in English. The reference lists of the selected articles were checked for additional sources. Results: We found that there were changes in emphasis in the research field over the four decades. There was an increasing tendency to study wide-ranging aspects of the determinants of mortality, including risk factors, lifestyle changes, socio-economics, and macro factors such as climate change. Research on ET has focused increasingly on low- and middle-income countries rather than industrialised countries, despite its origins in industrialised countries. Countries have experienced different levels of progress in ET in terms of time, pace, and underlying mechanisms. Elements of ET are described for many countries, but observed transitions have not always followed pathways described in the original theory. Conclusions: The classic ET theory largely neglected the critical role of social determinants, being largely a theoretical generalisation of mortality experience in some countries. This review shows increasing interest in ET all over the world but only partial concordance between established theory and empirical evidence. Empirical evidence suggests that some unconsidered aspects of social determinants contributed to deviations from classic
A Demographic Perspective on Family Change
Bianchi, Suzanne M.
2014-01-01
Demographic analysis seeks to understand how individual microlevel decisions about child-bearing, marriage and partnering, geographic mobility, and behaviors that influence health and longevity aggregate to macrolevel population trends and differentials in fertility, mortality and migration. In this review, I first discuss theoretical perspectives—classic demographic transition theory, the perspective of the “second demographic transition,” the spread of developmental idealism—that inform demographers’ understanding of macrolevel population change. Then, I turn to a discussion of the role that demographically informed data collection has played in illuminating family change since the mid-20th century in the United States. Finally, I discuss ways in which demographic theory and data collection might inform future areas of family research, particularly in the area of intergenerational family relationships and new and emerging family forms. PMID:26078785
Quantum optimal control theory applied to transitions in diatomic molecules
Lysebo, Marius; Veseth, Leif
2014-12-01
Quantum optimal control theory is applied to control electric dipole transitions in a real multilevel system. The specific system studied in the present work is comprised of a multitude of hyperfine levels in the electronic ground state of the OH molecule. Spectroscopic constants are used to obtain accurate energy eigenstates and electric dipole matrix elements. The goal is to calculate the optimal time-dependent electric field that yields a maximum of the transition probability for a specified initial and final state. A further important objective was to study the detailed quantum processes that take place during such a prescribed transition in a multilevel system. Two specific transitions are studied in detail. The computed optimal electric fields as well as the paths taken through the multitude of levels reveal quite interesting quantum phenomena.
New phase transitions in Chern–Simons matter theory
Directory of Open Access Journals (Sweden)
Ali Zahabi
2016-02-01
Full Text Available Applying the machinery of random matrix theory and Toeplitz determinants we study the level k, U(N Chern–Simons theory coupled with fundamental matter on S2×S1 at finite temperature T. This theory admits a discrete matrix integral representation, i.e. a unitary discrete matrix model of two-dimensional Yang–Mills theory. In this study, the effective partition function and phase structure of the Chern–Simons matter theory, in a special case with an effective potential namely the Gross–Witten–Wadia potential, are investigated. We obtain an exact expression for the partition function of the Chern–Simons matter theory as a function of k, N, T, for finite values and in the asymptotic regime. In the Gross–Witten–Wadia case, we show that ratio of the Chern–Simons matter partition function and the continuous two-dimensional Yang–Mills partition function, in the asymptotic regime, is the Tracy–Widom distribution. Consequently, using the explicit results for free energy of the theory, new second-order and third-order phase transitions are observed. Depending on the phase, in the asymptotic regime, Chern–Simons matter theory is represented either by a continuous or discrete two-dimensional Yang–Mills theory, separated by a third-order domain wall.
Extended ensemble theory, spontaneous symmetry breaking, and phase transitions
Xiao, Ming-wen
2006-09-01
In this paper, as a personal review, we suppose a possible extension of Gibbs ensemble theory so that it can provide a reasonable description of phase transitions and spontaneous symmetry breaking. The extension is founded on three hypotheses, and can be regarded as a microscopic edition of the Landau phenomenological theory of phase transitions. Within its framework, the stable state of a system is determined by the evolution of order parameter with temperature according to such a principle that the entropy of the system will reach its minimum in this state. The evolution of order parameter can cause a change in representation of the system Hamiltonian; different phases will realize different representations, respectively; a phase transition amounts to a representation transformation. Physically, it turns out that phase transitions originate from the automatic interference among matter waves as the temperature is cooled down. Typical quantum many-body systems are studied with this extended ensemble theory. We regain the Bardeen Cooper Schrieffer solution for the weak-coupling superconductivity, and prove that it is stable. We find that negative-temperature and laser phases arise from the same mechanism as phase transitions, and that they are unstable. For the ideal Bose gas, we demonstrate that it will produce Bose Einstein condensation (BEC) in the thermodynamic limit, which confirms exactly Einstein's deep physical insight. In contrast, there is no BEC either within the phonon gas in a black body or within the ideal photon gas in a solid body. We prove that it is not admissible to quantize the Dirac field by using Bose Einstein statistics. We show that a structural phase transition belongs physically to the BEC happening in configuration space, and that a double-well anharmonic system will undergo a structural phase transition at a finite temperature. For the O(N)-symmetric vector model, we demonstrate that it will yield spontaneous symmetry breaking and produce
Directory of Open Access Journals (Sweden)
Jianghua Liu
Full Text Available Radical declines in fertility and postponement of first reproduction during the recent human demographic transitions have posed a challenge to interpreting human behaviour in evolutionary terms. This challenge has stemmed from insufficient evolutionary insight into individual reproductive decision-making and the rarity of datasets recording individual long-term reproductive success throughout the transitions. We use such data from about 2,000 Finnish mothers (first births: 1880s to 1970s to show that changes in the maternal risk of breeding failure (no offspring raised to adulthood underlay shifts in both fertility and first reproduction. With steady improvements in offspring survival, the expected fertility required to satisfy a low risk of breeding failure became lower and observed maternal fertility subsequently declined through an earlier age at last reproduction. Postponement of the age at first reproduction began when this risk approximated zero-even for mothers starting reproduction late. Interestingly, despite vastly differing fertility rates at different stages of the transitions, the number of offspring successfully raised to breeding per mother remained relatively constant over the period. Our results stress the importance of assessing the long-term success of reproductive strategies by including measures of offspring quality and suggest that avoidance of breeding failure may explain several key features of recent life-history shifts in industrialized societies.
White, R G; Hall, C; Wolff, B
2007-05-01
A characteristic of African pre-transitional fertility regimes is large ideal family size. This has been used to support claims of cultural entrenchment of high fertility. Yet in Kenya fertility rates have fallen. In this paper this fall is explored in relation to trends in fertility norms and attitudes using four sequential cross-sectional surveys spanning the fertility transition in Kenya (1978, 1984, 1989 and 1998). The most rapid fall in the reported ideal family size occurred between 1984 and 1989, whilst the most rapid fall in the total fertility rate occurred 5 to 10 years later, between 1989 and 1998. Thus these data, spanning the fertility transition in Kenya, support the traditional demographic model that demand for fertility limitation drives fertility decline. These data also suggest that the decline in fertility norms over time was partly a period effect, as the reported ideal family size was seen to fall simultaneously in all age cohorts, and partly a cohort effect, as older age cohorts reporting higher ideal family sizes were replaced by younger cohorts reporting lower ideal family sizes. These data also suggest that a new fertility norm of four children may have developed by 1989 and continued until 1998. This is consistent with, and perhaps could have been used to predict, the stall in the Kenyan fertility decline after 1998.
Finite Line-transitive Linear Spaces: Theory and Search Strategies
Institute of Scientific and Technical Information of China (English)
Anton BETTEN; Anne DELANDTSHEER; Maska LAW; Alice C. NIEMEYER; Cheryl E. PRAEGER; Shenglin ZHOU
2009-01-01
The paper summarises existing theory and classifications for finite line-transitive linear spaces, develops the theory further, and organises it in a way that enables its effective application. The starting point is a theorem of Camina and the fifth author that identifies three kinds of line-transitive automorphism groups of linear spaces. In two of these cases the group may be imprimitive on points, that is, the group leaves invariant a nontrivial partition of the point set. In the first of these cases the group is almost simple with point-transitive simple socle, and may or may not be point-primitive, while in the second case the group has a non-trivial point-intransitive normal subgroup and hence is definitely point-imprimitive. The theory presented here focuses on point-imprimitive groups. As a non-trivial application a classification is given of the point-imprimitive, line-transitive groups, and the corresponding linear spaces, for which the greatest common divisor gcd(k, v - 1) ≤ 8, where v is the number of points, and k is the line size. Motivation for this classification comes from a result of Weidong Fang and Huiling Li in 1993, that there are only finitely many non-trivial point-imprimitive, line-transitive linear spaces for a given value of gcd(k, v- 1). The classification strengthens the classification by Camina and Mischke under the much stronger restriction k ≤ 8: no additional examples arise. The paper provides the backbone for future computer-based classifications of point-imprimitive, line-transitive linear spaces with small parameters. Several suggestions for further investigations are made.
Phase transitions of large N orbifold gauge theories
Energy Technology Data Exchange (ETDEWEB)
Hikida, Y.
2006-10-15
We study the phase structures of N=4 SU(N) super Yang-Mills theories on R x S{sup 3}/Z{sub k} with large N. The theory has many vacua labelled by the holonomy matrix along the non-trivial cycle on S{sup 3}/Z{sub k}, and for the fermions the periodic and the anti-periodic boundary conditions can be assigned along the cycle. We compute the partition functions of the orbifold theories and observe that phase transitions occur even in the zero 't Hooft coupling limit. With the periodic boundary condition, the vacua of the gauge theory are dual to various arrangements of k NS5-branes. With the anti-periodic boundary condition, transitions between the vacua are dual to localized tachyon condensations. In particular, the mass of a deformed geometry is compared with the Casimir energy for the dual vacuum. We also obtain an index for the supersymmetric orbifold theory. (orig.)
Directory of Open Access Journals (Sweden)
Manushaqe Rustani-Batku
2017-03-01
Full Text Available Aim: The aim of our study was to assess the distribution of socio-demographic factors and the clinical profile of individuals diagnosed with retinal vein occlusion (RVO in Albania, a former communist country in South-eastern Europe which has been undergoing a rapid transition in the past decades. Methods: This study was carried out in 2013-2016 at the Primary Health Care Centre No. 2 in Tirana municipality, which is the capital of Albania. During this timeframe, on the whole, 44 patients were diagnosed with RVO at this primary health care centre (17 women and 27 men; overall mean age: 69.5±11.5 years. The diagnosis of RVO was based on signs and symptoms indicating a quick reduction of the sight (vision, fundoscopy, fluorescein angiography and the optical coherence tomography. Data on socio-demographic factors and clinical characteristics were also gathered for each study participant. Results: The prevalence of glaucoma was considerably higher in men than in women (67% vs. 24%, respectively, P=0.01. Diabetic retinopathy was somehow more prevalent in women than in men (18% vs. 11%, respectively, whereas an opposite finding was noted for the presence of hypertensive retinopathy (6% vs. 11%, respectively. The prevalence of cataract was higher in female patients compared with their male counterparts (18% vs. 7%, respectively, P=0.36. Both macular oedema and papillary oedema were almost equally distributed in men and in women (22% vs. 18% and 4% vs. 6%, respectively. All female patients had comorbid conditions compared to 85% of their male counterparts (P=0.15. The prevalence of hypertension was almost identical in both sexes (52% in men vs. 53% in women, whereas the prevalence of diabetes was somehow higher in men than in women (26% vs. 18%, respectively. Conclusion: This is one of the very few studies informing about the distribution of socio-demographic factors and selected clinical characteristics of individuals diagnosed with RVO in
New Phase Transitions in Chern-Simons Matter Theory
Zahabi, Ali
2015-01-01
Applying the machinery of random matrix theory and Toeplitz determinants we study the level $k$, $U(N)$ Chern-Simons theory coupled with fundamental matter on $S^2\\times S^1$ at finite temperature $T$. This theory admits a discrete matrix integral representation, i.e. a unitary discrete matrix model of two-dimensional Yang-Mills theory. In this study, the partition function and phase structure of the Chern-Simons matter theory in an special case with Gross-Witten-Wadia potential are investigated. We obtain an exact expression for the partition function of the Chern-Simons matter theory as a function of $k,N,T$, for finite values and in the asymptotic regime. In the Gross-Witten-Wadia case, we show that ratio of the Chern-Simons matter partition function and the continuous two-dimensional Yang-Mills partition function, in the asymptotic regime, is the Tracy-Widom distribution. Consequently, using the explicit results for free energy of the theory, new second order and third-order phase transitions are observed...
Dual little strings from F-theory and flop transitions
Hohenegger, Stefan; Iqbal, Amer; Rey, Soo-Jong
2017-07-01
A particular two-parameter class of little string theories can be described by M parallel M5-branes probing a transverse affine A N - 1 singularity. We previously discussed the duality between the theories labelled by ( N, M) and ( M, N). In this work, we propose that these two are in fact only part of a larger web of dual theories. We provide evidence that the theories labelled by ( N, M) and (NM/k,k) are dual to each other, where k = gcd( N, M). To argue for this duality, we use a geometric realization of these little string theories in terms of F-theory compactifications on toric, non-compact Calabi-Yau threefolds X N, M which have a double elliptic fibration structure. We show explicitly for a number of examples that X NM/ k, k is part of the extended moduli space of X N, M , i.e. the two are related through symmetry transformations and flop transitions. By working out the full duality map, we provide a simple check at the level of the free energy of little string theories.
Dual Little Strings from F-Theory and Flop Transitions
Hohenegger, Stefan; Rey, Soo-Jong
2016-01-01
A particular two-parameter class of little string theories can be described by $M$ parallel M5-branes probing a transverse affine $A_{N-1}$ singularity. We previously discussed the duality between the theories labelled by $(N,M)$ and $(M,N)$. In this work, we propose that these two are in fact only part of a larger web of dual theories. We provide evidence that the theories labelled by $(N,M)$ and $(\\tfrac{NM}{k},k)$ are dual to each other, where $k=\\text{gcd}(N,M)$. To argue for this duality, we use a geometric realization of these little string theories in terms of F-theory compactifications on toric, non-compact Calabi-Yau threefolds $X_{N,M}$ which have a double elliptic fibration structure. We show explicitly for a number of examples that $X_{NM/k,k}$ is part of the extended moduli space of $X_{N,M}$, i.e. the two are related through symmetry transformations and flop transitions. By working out the full duality map, we provide a simple check at the level of the free energy of the little string theories.
Density functional theory studies of transition metal nanoparticles in catalysis
DEFF Research Database (Denmark)
Greeley, Jeffrey Philip; Rankin, Rees; Zeng, Zhenhua
2013-01-01
Periodic Density Functional Theory calculations are capable of providing powerful insights into the structural, energetics, and electronic phenomena that underlie heterogeneous catalysis on transition metal nanoparticles. Such calculations are now routinely applied to single crystal metal surfaces...... and to subnanometer metal clusters. Descriptions of catalysis on truly nanosized structures, however, are generally not as well developed. In this talk, I will illustrate different approaches to analyzing nanocatalytic phenomena with DFT calculations. I will describe case studies from heterogeneous catalysis...
Transitional clerkship: an experiential course based on workplace learning theory.
Chittenden, Eva H; Henry, Duncan; Saxena, Varun; Loeser, Helen; O'Sullivan, Patricia S
2009-07-01
Starting clerkships is anxiety provoking for medical students. To ease the transition from preclerkship to clerkship curricula, schools offer classroom-based courses which may not be the best model for preparing learners. Drawing from workplace learning theory, the authors developed a seven-day transitional clerkship (TC) in 2007 at the University of California, San Francisco School of Medicine in which students spent half of the course in the hospital, learning routines and logistics of the wards along with their roles and responsibilities as members of ward teams. Twice, they admitted and followed a patient into the next day as part of a shadow team that had no patient-care responsibilities. Dedicated preceptors gave feedback on oral presentations and patient write-ups. Satisfaction with the TC was higher than with the previous year's classroom-based course. TC students felt clearer about their roles and more confident in their abilities as third-year students compared with previous students. TC students continued to rate the transitional course highly after their first clinical rotation. Preceptors were enthusiastic about the course and expressed willingness to commit to future TC preceptorships. The transitional course models an approach to translating workplace learning theory into practice and demonstrates improved satisfaction, better understanding of roles, and increased confidence among new third-year students.
Navarro, Jordana N; Jasinski, Jana L
2015-01-01
This article presents an analysis of the relationship between online sexual offenders' demographic background and characteristics indicative of motivation and offense type. Specifically, we investigate whether these characteristics can distinguish different online sexual offender groups from one another as well as inform routine activity theorists on what potentially motivates perpetrators. Using multinomial logistic regression, this study found that online sexual offenders' demographic backgrounds and characteristics indicative of motivation do vary by offense types. Two important implications of this study are that the term "online sexual offender" encompasses different types of offenders, including some who do not align with mainstream media's characterization of "predators," and that the potential offender within routine activity theory can be the focus of empirical investigation rather than taken as a given in research.
Moorad, Jacob A
2013-06-01
Modernization has increased longevity and decreased fertility in many human populations, but it is not well understood how or to what extent these demographic transitions have altered patterns of natural selection. I integrate individual-based multivariate phenotypic selection approaches with evolutionary demographic methods to demonstrate how a demographic transition in 19th century female populations of Utah altered relationships between fitness and age-specific survival and fertility. Coincident with this demographic transition, natural selection for fitness, as measured by the opportunity for selection, increased by 13% to 20% over 65 years. Proportional contributions of age-specific survival to total selection (the complement to age-specific fertility) diminished from approximately one third to one seventh following a marked increase in infant survival. Despite dramatic reductions in age-specific fertility variance at all ages, the absolute magnitude of selection for fitness explained by age-specific fertility increased by approximately 45%. I show that increases in the adaptive potential of fertility traits followed directly from decreased population growth rates. These results suggest that this demographic transition has increased the adaptive potential of the Utah population, intensified selection for reproductive traits, and de-emphasized selection for survival-related traits. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.
Disease introduction is associated with a phase transition in bighorn sheep demographics
Manlove, Kezia; Cassirer, E. Frances; Cross, Paul C.; Plowright, Raina K.; Hudson, Peter J.
2016-01-01
Ecological theory suggests that pathogens are capable of regulating or limiting host population dynamics, and this relationship has been empirically established in several settings. However, although studies of childhood diseases were integral to the development of disease ecology, few studies show population limitation by a disease affecting juveniles. Here, we present empirical evidence that disease in lambs constrains population growth in bighorn sheep (Ovis canadensis) based on 45 years of population-level and 18 years of individual-level monitoring across 12 populations. While populations generally increased (λ = 1.11) prior to disease introduction, most of these same populations experienced an abrupt change in trajectory at the time of disease invasion, usually followed by stagnant-to-declining growth rates (λ = 0.98) over the next 20 years. Disease-induced juvenile mortality imposed strong constraints on population growth that were not observed prior to disease introduction, even as adult survival returned to pre-invasion levels. Simulations suggested that models including persistent disease-induced mortality in juveniles qualitatively matched observed population trajectories, whereas models that only incorporated all-age disease events did not. We use these results to argue that pathogen persistence may pose a lasting, but under-recognized, threat to host populations, particularly in cases where clinical disease manifests primarily in juveniles.
New Theories on Boundary Layer Transition and Turbulence Formation
Directory of Open Access Journals (Sweden)
Chaoqun Liu
2012-01-01
Full Text Available This paper is a short review of our recent DNS work on physics of late boundary layer transition and turbulence. Based on our DNS observation, we propose a new theory on boundary layer transition, which has five steps, that is, receptivity, linear instability, large vortex structure formation, small length scale generation, loss of symmetry and randomization to turbulence. For turbulence generation and sustenance, the classical theory, described with Richardson's energy cascade and Kolmogorov length scale, is not observed by our DNS. We proposed a new theory on turbulence generation that all small length scales are generated by “shear layer instability” through multiple level ejections and sweeps and consequent multiple level positive and negative spikes, but not by “vortex breakdown.” We believe “shear layer instability” is the “mother of turbulence.” The energy transferring from large vortices to small vortices is carried out by multiple level sweeps, but does not follow Kolmogorov's theory that large vortices pass energy to small ones through vortex stretch and breakdown. The loss of symmetry starts from the second level ring cycle in the middle of the flow field and spreads to the bottom of the boundary layer and then the whole flow field.
Density Functional Theory for Phase-Ordering Transitions
Energy Technology Data Exchange (ETDEWEB)
Wu, Jianzhong [Univ. of California, Riverside, CA (United States)
2016-03-30
Colloids display astonishing structural and dynamic properties that can be dramatically altered by modest changes in the solution condition or an external field. This complex behavior stems from a subtle balance of colloidal forces and intriguing mesoscopic and macroscopic phase transitions that are sensitive to the processing conditions and the dispersing environment. Whereas the knowledge on the microscopic structure and phase behavior of colloidal systems at equilibrium is now well-advanced, quantitative predictions of the dynamic properties and the kinetics of phase-ordering transitions in colloids are not always realized. Many important mesoscopic and off-equilibrium colloidal states remain poorly understood. The proposed research aims to develop a new, unifying approach to describe colloidal dynamics and the kinetics of phase-ordering transitions based on accomplishments from previous work for the equilibrium properties of both uniform and inhomogeneous systems and on novel concepts from the state-of-the-art dynamic density functional theory. In addition to theoretical developments, computational research is designed to address a number of fundamental questions on phase-ordering transitions in colloids, in particular those pertinent to a competition of the dynamic pathways leading to various mesoscopic structures, off-equilibrium states, and crystalline phases. By providing a generic theoretical framework to describe equilibrium, metastable as well as non-ergodic phase transitions concurrent with the colloidal self-assembly processes, accomplishments from this work will have major impacts on both fundamental research and technological applications.
A Theory of Exoplanet Transits with Light Scattering
Robinson, Tyler D.
2017-02-01
Exoplanet transit spectroscopy enables the characterization of distant worlds, and will yield key results for NASA's James Webb Space Telescope. However, transit spectra models are often simplified, omitting potentially important processes like refraction and multiple scattering. While the former process has seen recent development, the effects of light multiple scattering on exoplanet transit spectra have received little attention. Here, we develop a detailed theory of exoplanet transit spectroscopy that extends to the full refracting and multiple scattering case. We explore the importance of scattering for planet-wide cloud layers, where the relevant parameters are the slant scattering optical depth, the scattering asymmetry parameter, and the angular size of the host star. The latter determines the size of the “target” for a photon that is back-mapped from an observer. We provide results that straightforwardly indicate the potential importance of multiple scattering for transit spectra. When the orbital distance is smaller than 10–20 times the stellar radius, multiple scattering effects for aerosols with asymmetry parameters larger than 0.8–0.9 can become significant. We provide examples of the impacts of cloud/haze multiple scattering on transit spectra of a hot Jupiter-like exoplanet. For cases with a forward and conservatively scattering cloud/haze, differences due to multiple scattering effects can exceed 200 ppm, but shrink to zero at wavelength ranges corresponding to strong gas absorption or when the slant optical depth of the cloud exceeds several tens. We conclude with a discussion of types of aerosols for which multiple scattering in transit spectra may be important.
Bohner, Katja
2016-10-03
Transitions Theory (TT) states that change and transition are phenomena that make humans more vulnerable to health risks. Transitions Theory was evaluated through a text analysis of 4 publications, 3 nursing expert focus group interviews in Switzerland, and a mapping review of the transition literature of the last 5 years. Although the implementation of TT into Swiss nursing practice seems problematic due to conceptual deficiencies, transition is a meaningful nursing topic. The connection between TT, research, and practice is weak. Yet guidelines for theory description, theory analysis, and theory actualization could enhance and strengthen the body of knowledge in nursing.
Fourth-Order Vibrational Transition State Theory and Chemical Kinetics
Stanton, John F.; Matthews, Devin A.; Gong, Justin Z.
2015-06-01
Second-order vibrational perturbation theory (VPT2) is an enormously successful and well-established theory for treating anharmonic effects on the vibrational levels of semi-rigid molecules. Partially as a consequence of the fact that the theory is exact for the Morse potential (which provides an appropriate qualitative model for stretching anharmonicity), VPT2 calculations for such systems with appropriate ab initio potential functions tend to give fundamental and overtone levels that fall within a handful of wavenumbers of experimentally measured positions. As a consequence, the next non-vanishing level of perturbation theory -- VPT4 -- offers only slight improvements over VPT2 and is not practical for most calculations since it requires information about force constants up through sextic. However, VPT4 (as well as VPT2) can be used for other applications such as the next vibrational correction to rotational constants (the ``gammas'') and other spectroscopic parameters. In addition, the marriage of VPT with the semi-classical transition state theory of Miller (SCTST) has recently proven to be a powerful and accurate treatment for chemical kinetics. In this talk, VPT4-based SCTST tunneling probabilities and cumulative reaction probabilities are give for the first time for selected low-dimensional model systems. The prospects for VPT4, both practical and intrinsic, will also be discussed.
Insights into phase transitions and entanglement from density functional theory
Wei, Bo-Bo
2016-11-01
Density functional theory (DFT) has met great success in solid state physics, quantum chemistry and in computational material sciences. In this work we show that DFT could shed light on phase transitions and entanglement at finite temperatures. Specifically, we show that the equilibrium state of an interacting quantum many-body system which is in thermal equilibrium with a heat bath at a fixed temperature is a universal functional of the first derivatives of the free energy with respect to temperature and other control parameters respectively. This insight from DFT enables us to express the average value of any physical observable and any entanglement measure as a universal functional of the first derivatives of the free energy with respect to temperature and other control parameters. Since phase transitions are marked by the nonanalytic behavior of free energy with respect to control parameters, the physical quantities and entanglement measures may present nonanalytic behavior at critical point inherited from their dependence on the first derivative of free energy. We use two solvable models to demonstrate these ideas. These results give new insights for phase transitions and provide new profound connections between entanglement and phase transitions in interacting quantum many-body physics.
Quantum Transition State Theory for proton transfer reactions in enzymes
Bothma, Jacques P; McKenzie, Ross H
2009-01-01
We consider the role of quantum effects in the transfer of hyrogen-like species in enzyme-catalysed reactions. This study is stimulated by claims that the observed magnitude and temperature dependence of kinetic isotope effects imply that quantum tunneling below the energy barrier associated with the transition state significantly enhances the reaction rate in many enzymes. We use a path integral approach which provides a general framework to understand tunneling in a quantum system which interacts with an environment at non-zero temperature. Here the quantum system is the active site of the enzyme and the environment is the surrounding protein and water. Tunneling well below the barrier only occurs for temperatures less than a temperature $T_0$ which is determined by the curvature of potential energy surface near the top of the barrier. We argue that for most enzymes this temperature is less than room temperature. For physically reasonable parameters quantum transition state theory gives a quantitative descr...
Bovolenta, Tânia M; Felicio, Andre C
2017-01-01
Brazil is currently experiencing a significant demographic transition characterized by a decrease in fertility rates and an exponential increase in the number of elderly citizens, which presents a special challenge for the health care professionals. More than other portions of the population, the elderly are most commonly affected by chronic diseases such as Parkinson’s disease. Policymakers contend that Brazil is reasonably well-prepared regarding elderly health care, with policies that aim to ensure the quality of life and the well-being of this portion of the population. However, what happens in practice falls short of what the Brazilian Constitution sets forth. Specifically, there is a clear contradiction between what the law recognizes as being a citizen’s rights and the implementation of guidelines. Because health financing in Brazil remains relatively low, the civil society tries to fill in the gaps as much as possible in the treatment of elderly patients suffering from chronic diseases such as Parkinson’s disease. In this review, we outline the current legislation in Brazil regarding the elderly and in particular, patients with Parkinson’s disease, in the context of a rapidly aging population. PMID:28182156
Merler, Stefano; Ajelli, Marco
2014-02-22
In Italy, during the course of the past century to the present-day, measles incidence underwent a remarkable decreasing trend that started well before the introduction of the national immunization programme. In this work, we aim at examining to what extent both the demographic transition, characterized by declining mortality and fertility rates over time, and the vaccination programme are responsible for the observed epidemiological pattern. Making use of a non-stationary, age-structured disease transmission model, we show that in the pre-vaccination era, from 1901 to 1982, the decline in birth rates has resulted in a drastic decrease in the effective transmission rate, which in turn has determined a declining trend of measles incidence (from 25.2 to 10.3 infections per 1000 individuals). However, since 1983, vaccination appears to have become the major contributing factor in the decrease of measles incidence, which otherwise would have remained stable as a consequence of the nearly constant birth rates. This led to a remarkable decrease in the effective transmission rate, to a level well below the critical threshold for disease persistence. These findings call for the adoption of epidemiological models, which deviate the age structure from stationary equilibrium solutions, to better understand the biology of infectious diseases and evaluate immunization programmes.
Zupančič, Maja; Komidar, Luka; Levpušček, Melita Puklek
2014-12-01
The study investigated associations of Slovene emerging adults' age, gender, living situation, romantic relationship, and employment status with aspects of individuation in relation to mother and father. Controlling for demographic variables and transitional markers of adulthood, we further explored the contribution of individuation measures to individuals' perceptions of achieved criteria for adulthood and life satisfaction. The participants provided self-reports on the Individuation Test for Emerging Adults, the Satisfaction With Life Scale, and the list of Achieved Criteria for Adulthood. Age and living out of parental home were positively associated with self-reliance in relation to both parents, whereas female gender was related to higher levels of connectedness and seeking parental support. Along with age and involvement in a romantic relationship, connectedness and self-reliance predicted adulthood criteria attainment and life satisfaction. The results support the models of individuation that emphasize growing autonomy and retaining connectedness to parents as pathways towards personal adjustments. Copyright © 2014 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Gavin W. Jones
2011-12-01
Full Text Available This paper covers a wide scope, focusing on some trends in East and Southeast Asia that may be of interest to Latin America. The first demographic transition has essentially been completed in both regions. The issue is what should now be the focus of our consideration of population and development? East Asian countries are now stressing issues of ultra-low fertility, and policies to raise fertility. They are not comfortable with the prospect of making up future deficits through international migration. The paper also deals briefly with studies of dynamics of change in mega-urban regions, and argues that comparative studies on Latin America and Asia could be valuable. Issues of poverty, development, and equity are then addressed, with particular emphasis on the role of education as a key to equality and development. One dilemma is that in East Asia, the generally commendable obsession with education is one factor making for very low levels of fertility. Finally, the paper touches on population and environmental issues.
Europe's Second Demographic Transition.
van de Kaa, Dirk J.
1987-01-01
By 1985, fertility rates in Europe were below the replacement level of 2.1 births per woman in all but Albania, Ireland, Malta, Poland, and Turkey, following a steady decline from a 1965 postwar peak well above 2.5 in Northern, Western, and Southern Europe and an erratic trend from a lower level in Eastern Europe. Natural decrease (fewer births…
Assessment of Prevalence of Persons with Down Syndrome: A Theory-Based Demographic Model
de Graaf, Gert; Vis, Jeroen C.; Haveman, Meindert; van Hove, Geert; de Graaf, Erik A. B.; Tijssen, Jan G. P.; Mulder, Barbara J. M.
2011-01-01
Background: The Netherlands are lacking reliable empirical data in relation to the development of birth and population prevalence of Down syndrome. For the UK and Ireland there are more historical empirical data available. A theory-based model is developed for predicting Down syndrome prevalence in the Netherlands from the 1950s onwards. It is…
Childhood obesity in transition zones: an analysis using structuration theory.
Chan, Christine; Deave, Toity; Greenhalgh, Trisha
2010-07-01
Childhood obesity is particularly prevalent in areas that have seen rapid economic growth, urbanisation, cultural transition, and commodification of food systems. Structuration theory may illuminate the interaction between population and individual-level causes of obesity. We conducted in-depth ethnographies of six overweight/obese and four non-overweight preschool children in Hong Kong, each followed for 12-18 months. Analysis was informed by Stones' strong structuration theory. Risk factors played out differently for different children as social structures were enacted at the level of family and preschool. The network of caregiving roles and relationships around the overweight/obese child was typically weak and disjointed, and the primary caregiver appeared confused by mixed messages about what is normal, expected and legitimate behaviour. In particular, external social structures created pressure to shift childcare routines from the logic of nurturing to the logic of consumption. Our findings suggest that threats to what Giddens called ontological security in the primary caregiver may underpin the poor parenting, family stress and weak mealtime routines that mediate the relationship between an obesogenic environment and the development of obesity in a particular child. This preliminary study offers a potentially transferable approach for studying emerging epidemics of diseases of modernity in transition societies.
Transition State Theory: Variational Formulation, Dynamical Corrections, and Error Estimates
vanden-Eijnden, Eric
2009-03-01
Transition state theory (TST) is discussed from an original viewpoint: it is shown how to compute exactly the mean frequency of transition between two predefined sets which either partition phase space (as in TST) or are taken to be well separate metastable sets corresponding to long-lived conformation states (as necessary to obtain the actual transition rate constants between these states). Exact and approximate criterions for the optimal TST dividing surface with minimum recrossing rate are derived. Some issues about the definition and meaning of the free energy in the context of TST are also discussed. Finally precise error estimates for the numerical procedure to evaluate the transmission coefficient κS of the TST dividing surface are given, and it shown that the relative error on κS scales as 1/√κS when κS is small. This implies that dynamical corrections to the TST rate constant can be computed efficiently if and only if the TST dividing surface has a transmission coefficient κS which is not too small. In particular the TST dividing surface must be optimized upon (for otherwise κS is generally very small), but this may not be sufficient to make the procedure numerically efficient (because the optimal dividing surface has maximum κS, but this coefficient may still be very small).
Theory of the pairbreaking superconductor-metal transition in nanowires
Sachdev, Subir
2009-03-01
We present a detailed description of a zero temperature phase transition between superconducting and diffusive metallic states in very thin wires due to a Cooper pair breaking mechanism. The dissipative critical theory contains current reducing fluctuations in the guise of both quantum and thermally activated phase slips. A full cross-over phase diagram is computed via an expansion in the inverse number of complex components of the superconducting order parameter (one in the physical case). The fluctuation corrections to the electrical (σ) and thermal (κ) conductivities are determined, and we find that σ has a non-monotonic temperature dependence in the metallic phase which may be consistent with recent experimental results on ultra-narrow wires. In the quantum critical regime, the ratio of the thermal to electrical conductivity displays a linear temperature dependence and thus the Wiedemann-Franz law is obeyed, with a new universal experimentally verifiable Lorenz number. We also examined the influence of quenched disorder on the superconductor-metal transition. The self-consistent pairing eigenmodes of a quasi-one dimensional wire were determined numerically. Our results support the proposal by Hoyos et al./ (Phys. Rev. Lett. 99, 230601 (2007)) that the transition is described by the same strong disorder fixed point describing the onset of ferromagnetism in the quantum Ising model in a transverse field.
Transition Theory: A Novel Theory of the Universe Creation and Evolution
Vlachogiannis, J. G.
2004-08-01
This paper presents a novel theory attempting to point out the perpetual transition of Universe and natural systems progressing from Big Bang to endless Quenching. It defines the increase of speed-of-light and space-dimensions number according to Fibonacci sequence Moreover, it proofs that the Time in our Universe is composed of its changes and its representation in n-4 hidden dimensions of an n-dimensional Universe
K-theory and phase transitions at high energies
Directory of Open Access Journals (Sweden)
T. V. Obikhod
2016-06-01
Full Text Available The duality between E8xE8 heteritic string on manifold K3xT2 and Type IIA string compactified on a Calabi-Yau manifold induces a correspondence between vector bundles on K3xT2 and Calabi-Yau manifolds. Vector bundles over compact base space K3xT2 form the set of isomorphism classes, which is a semi-ring under the operation of Whitney sum and tensor product. The construction of semi-ring V ect X of isomorphism classes of complex vector bundles over X leads to the ring KX = K(V ect X, called Grothendieck group. As K3 has no isometries and no non-trivial one-cycles, so vector bundle winding modes arise from the T2 compactification. Since we have focused on supergravity in d = 11, there exist solutions in d = 10 for which space-time is Minkowski space and extra dimensions are K3xT2. The complete set of soliton solutions of supergravity theory is characterized by RR charges, identified by K-theory. Toric presentation of Calabi-Yau through Batyrev's toric approximation enables us to connect transitions between Calabi-Yau manifolds, classified by enhanced symmetry group, with K-theory classification.
Transition State Theory for dissipative systems without a dividing surface
Revuelta, F; Benito, R M; Borondo, F
2015-01-01
Transition State Theory is a central cornerstone in reaction dynamics. Its key step is the identification of a dividing surface that is crossed only once by all reactive trajectories. This assumption is often badly violated, especially when the reactive system is coupled to an environment. The calculations made in this way then overestimate the reaction rate and the results depend critically on the choice of the dividing surface. In this Letter, we study the phase space of a stochastically driven system close to an energetic barrier in order to identify the geometric structure unambiguously determining the reactive trajectories, which is then incorporated in a simple rate formula for reactions in condensed phase that is both independent of the dividing surface and exact.
Automated Transition State Theory Calculations for High-Throughput Kinetics.
Bhoorasingh, Pierre L; Slakman, Belinda L; Seyedzadeh Khanshan, Fariba; Cain, Jason Y; West, Richard Henry
2017-08-18
A scarcity of known chemical kinetic parameters leads to the use of many reaction rate estimates, which are not always sufficiently accurate, in the construction of detailed kinetic models. To reduce the reliance on these estimates and improve the accuracy of predictive kinetic models, we have developed a high-throughput, fully automated, reaction rate calculation method, AutoTST. The algorithm integrates automated saddle-point geometry search methods and a canonical transition state theory kinetics calculator. The automatically calculated reaction rates compare favorably to existing estimated rates. Comparison against high level theoretical calculations show the new automated method performs better than rate estimates when the estimate is made by a poor analogy. The method will improve by accounting for internal rotor contributions and by improving methods to determine molecular symmetry.
Accelerating cosmologies and a phase transition in M-theory
Energy Technology Data Exchange (ETDEWEB)
Wohlfarth, Mattias N.R
2003-06-19
M-theory compactifies on a seven-dimensional time-dependent hyperbolic or flat space to a four-dimensional FLRW cosmology undergoing a period of accelerated expansion in Einstein conformal frame. The strong energy condition is violated by the scalar fields produced in the compactification, as is necessary to evade the no-go theorem for time-independent compactifications. The four-form field strength of eleven-dimensional supergravity smoothly switches on during the period of accelerated expansion in hyperbolic compactifications, whereas in flat compactifications, the three-form potential smoothly changes its sign. For small acceleration times, this behaviour is like a phase transition of the three-form potential, during which the cosmological scale factor approximately doubles.
Accelerating Cosmologies and a Phase Transition in M-Theory
Wohlfarth, M N R
2003-01-01
M-theory compactifies on a seven-dimensional time-dependent hyperbolic or flat space to a four-dimensional FLRW cosmology undergoing a period of accelerated expansion in Einstein conformal frame. The strong energy condition is violated by the scalar fields produced in the compactification, as is necessary to evade the no-go theorem for time-independent compactifications. The four-form field strength of eleven-dimensional supergravity smoothly switches on during the period of accelerated expansion in hyperbolic compactifications, whereas in flat compactifications, the three-form potential smoothly changes its sign. For small acceleration times, this behaviour is like a phase transition of the three-form potential, during which the cosmological scale factor approximately doubles.
Boschma, R.A.; Coenen, Lars; Frenken, K.; Truffer, B.
2017-01-01
Towards a theory of regional diversification: combining insights from Evolutionary Economic Geography and Transition Studies. Regional Studies. This paper develops a theoretical framework of regional diversification by combining insights from Evolutionary Economic Geography and Transition Studies.
Random walk theory and exchange rate dynamics in transition economies
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Gradojević Nikola
2010-01-01
Full Text Available This paper investigates the validity of the random walk theory in the Euro-Serbian dinar exchange rate market. We apply Andrew Lo and Archie MacKinlay's (1988 conventional variance ratio test and Jonathan Wright's (2000 non-parametric ranks and signs based variance ratio tests to the daily Euro/Serbian dinar exchange rate returns using the data from January 2005 - December 2008. Both types of variance ratio tests overwhelmingly reject the random walk hypothesis over the data span. To assess the robustness of our findings, we examine the forecasting performance of a non-linear, nonparametric model in the spirit of Francis Diebold and James Nason (1990 and find that it is able to significantly improve upon the random walk model, thus confirming the existence of foreign exchange market imperfections in a small transition economy such as Serbia. In the last part of the paper, we conduct a comparative study on how our results relate to those of other transition economies in the region.
Transition-state theory predicts clogging at the microscale
Laar, T. Van De; Klooster, S. Ten; Schroën, K.; Sprakel, J.
2016-06-01
Clogging is one of the main failure mechanisms encountered in industrial processes such as membrane filtration. Our understanding of the factors that govern the build-up of fouling layers and the emergence of clogs is largely incomplete, so that prevention of clogging remains an immense and costly challenge. In this paper we use a microfluidic model combined with quantitative real-time imaging to explore the influence of pore geometry and particle interactions on suspension clogging in constrictions, two crucial factors which remain relatively unexplored. We find a distinct dependence of the clogging rate on the entrance angle to a membrane pore which we explain quantitatively by deriving a model, based on transition-state theory, which describes the effect of viscous forces on the rate with which particles accumulate at the channel walls. With the same model we can also predict the effect of the particle interaction potential on the clogging rate. In both cases we find excellent agreement between our experimental data and theory. A better understanding of these clogging mechanisms and the influence of design parameters could form a stepping stone to delay or prevent clogging by rational membrane design.
Towards a new pattern of transition to adulthood?
Billari, F.; Liefbroer, A.C.
2010-01-01
Second Demographic TransitionRecent theories about social and demographic change, such as individualization and the Second Demographic Transition, embed the notion of a convergence towards a specific ideal-typical pathway to adulthood, which we define as late, protracted and complex. After a discuss
Easterbrooks, Susan R.; Miller, Daniel L.
1996-01-01
Describes a blending of Glasser's Choice Theory/Reality Therapy with transition and pragmatic language theories to establish a process that speech/language pathologists may use in managing and implementing transition services. A rationale and blended model is provided, and sample Individualized Education Program objectives are given. (Author/CR)
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Ayaga Bawah
Full Text Available This paper contributes evidence documenting the continued decline in all-cause mortality and changes in the cause of death distribution over time in four developing country populations in Africa and Asia. We present levels and trends in age-specific mortality (all-cause and cause-specific from four demographic surveillance sites: Agincourt (South Africa, Navrongo (Ghana in Africa; Filabavi (Vietnam, Matlab (Bangladesh in Asia. We model mortality using discrete time event history analysis. This study illustrates how data from INDEPTH Network centers can provide a comparative, longitudinal examination of mortality patterns and the epidemiological transition. Health care systems need to be reconfigured to deal simultaneously with continuing challenges of communicable disease and increasing incidence of non-communicable diseases that require long-term care. In populations with endemic HIV, long-term care of HIV patients on ART will add to the chronic care needs of the community.
Safety models incorporating graph theory based transit indicators.
Quintero, Liliana; Sayed, Tarek; Wahba, Mohamed M
2013-01-01
There is a considerable need for tools to enable the evaluation of the safety of transit networks at the planning stage. One interesting approach for the planning of public transportation systems is the study of networks. Network techniques involve the analysis of systems by viewing them as a graph composed of a set of vertices (nodes) and edges (links). Once the transport system is visualized as a graph, various network properties can be evaluated based on the relationships between the network elements. Several indicators can be calculated including connectivity, coverage, directness and complexity, among others. The main objective of this study is to investigate the relationship between network-based transit indicators and safety. The study develops macro-level collision prediction models that explicitly incorporate transit physical and operational elements and transit network indicators as explanatory variables. Several macro-level (zonal) collision prediction models were developed using a generalized linear regression technique, assuming a negative binomial error structure. The models were grouped into four main themes: transit infrastructure, transit network topology, transit route design, and transit performance and operations. The safety models showed that collisions were significantly associated with transit network properties such as: connectivity, coverage, overlapping degree and the Local Index of Transit Availability. As well, the models showed a significant relationship between collisions and some transit physical and operational attributes such as the number of routes, frequency of routes, bus density, length of bus and 3+ priority lanes.
Liu, T; Flöthmann, E-J
2013-07-01
In China, fundamental changes in population development have occurred during the past 50 years. The demographic transition in China required only a few years, while in most European countries this process took several decades. The fertility and mortality rates have declined very quickly, like in Japan and South Korea. China is one of the countries that has passed through the transition process the quickest. In the following article, this development is considered in more detail. Even if the fertility and mortality rates should stabilize at a new low level, which today certainly cannot be conclusively stated, the age effects will persist for the next few decades. The demographic aging during recent years will increase enormously in the coming decades. This development leads to far-reaching social and political challenges. The demographic aging in China is associated with a loss of function of the family. Both developments have a strong impact on the old-age insurance and on old-age care. Only a few years ago did politics and society start to respond with comprehensive reforms. For example, a modern pension system was introduced, but only in urban areas of China. Rural populations are still waiting for such reforms even today. Currently, there is a pilot project to gain experience with a pension system for the entire population. In contrast to the old-age insurance, in China there is very little public interest in old-age care because the elderly have until now been only a matter for the family. In the near future, the changing role of family and demographic aging will require a greater discussion about the care of older people in China.
Bolund, E; Lummaa, V
2017-02-01
Studies of evolutionary change require an estimate of fitness, and lifetime reproductive success is widely used for this purpose. However, many species face a trade-off between the number and quality of offspring and in such cases number of grandoffspring may better represent the genetic contribution to future generations. Here, we apply quantitative genetic methods to a genealogical data set on humans from Finland to address how the genetic correlation between number of children and grandchildren is influenced by the severity of the trade-off between offspring quality and quantity, as estimated by different levels of resource access among individuals in the population. Further, we compare the genetic correlation before and after the demographic transition to low mortality and fertility rates. The genetic correlation was consistently high (0.79-0.92) with the strongest correlations occurring in individuals with higher access to resources and before the demographic transition, and a tendency for lower correlations in resource poor individuals and after the transition. These results indicate that number of grandoffspring is a slightly better predictor of long-term genetic fitness than number of offspring in a human population across a range of environmental conditions, and more generally, that patterns of resource availability need to be taken into account when estimating genetic covariances with fitness.
Wang, Yingning; Sung, Hai-Yen; Yao, Tingting; Lightwood, James; Max, Wendy
2017-05-01
To examine the transitions in smoking status among non-daily smokers who transitioned to daily or former smokers or remained as non-daily smokers during a 12-month period. We analyzed factors associated with these transitions, including the use of cigars and smokeless tobacco (SLT). Secondary data analyses using pooled data from the 2003, 2006/07 and 2010/11 Tobacco Use Supplements to the Current Population Survey (TUS-CPS). United States. Self-respondents aged 18+ who have smoked for more than 5 years and were non-daily smokers 12 months before the interview (n = 13 673, or 14.5% of current smokers). Multinomial logistic regression model to determine the correlates of non-daily to daily, stable non-daily and non-daily to former smoking transitions among non-daily smokers at baseline. The model controlled for socio-demographic factors and the use of cigars and SLT. Of the adults in our sample, 2.6% were non-daily smokers at baseline. Among these, 69.7% remained non-daily smokers (stable non-daily smokers), 18.4% became daily smokers (non-daily to daily smokers) and 11.9% quit smoking (non-daily to former smokers) after 12 months. The non-daily to daily versus stable non-daily smoking transition was less likely among those who were aged 65+ (P = 0.018), male (P socio-demographic factors and current use of cigars and smokeless tobacco. © 2016 Society for the Study of Addiction.
Exotic axion cosmology in theories with phase transitions below the QCD scale.
Kaplan, David B; Zurek, Kathryn M
2006-02-03
We show that axion phenomenology may be significantly different than conventionally assumed in theories which exhibit late phase transitions (below the QCD scale). In such theories, one can find multiple pseudoscalars with axionlike couplings to matter, including a string scale axion, whose decay constant far exceeds the conventional cosmological bound. Such theories have several dark matter candidates.
Selection Bias in Educational Transition Models: Theory and Empirical Evidence
DEFF Research Database (Denmark)
Holm, Anders; Jæger, Mads
Most studies using Mare’s (1980, 1981) seminal model of educational transitions find that the effect of family background decreases across transitions. Recently, Cameron and Heckman (1998, 2001) have argued that the “waning coefficients” in the Mare model are driven by selection on unobserved...... the United States, United Kingdom, Denmark, and the Netherlands shows that when we take selection into account the effect of family background variables on educational transitions is largely constant across transitions. We also discuss several difficulties in estimating educational transition models which...... variables. This paper, first, explains theoretically how selection on unobserved variables leads to waning coefficients and, second, illustrates empirically how selection leads to biased estimates of the effect of family background on educational transitions. Our empirical analysis using data from...
Stochastic theory of synchronization transitions in extended systems
Munoz, Miguel A.; Pastor-Satorras, Romualdo
2003-01-01
We propose a general Langevin equation describing the universal properties of synchronization transitions in extended systems. By means of theoretical arguments and numerical simulations we show that the proposed equation exhibits, depending on parameter values, either: i) a continuous transition in the bounded Kardar-Parisi-Zhang universality class, with a zero largest Lyapunov exponent at the critical point; ii) a continuous transition in the directed percolation class, with a negative Lyap...
Fully Consistent Finite-Strain Landau Theory for High-Pressure Phase Transitions
Tröster, A.; Schranz, W.; Karsai, F.; Blaha, P.
2014-07-01
Landau theory (LT) is an indispensable cornerstone in the thermodynamic description of phase transitions. As with structural transitions, most applications require one to consistently take into account the role of strain. If temperature drives the transition, the relevant strains are, as a rule, small enough to be treated as infinitesimal, and therefore one can get away with linearized elasticity theory. However, for transitions driven by high pressure, strains may become so large that it is absolutely mandatory to treat them as finite and deal with the nonlinear nature of the accompanying elastic energy. In this paper, we explain how to set up and apply what is, in fact, the only possible consistent Landau theory of high-pressure phase transitions that systematically allows us to take these geometrical and physical nonlinearities into account. We also show how to incorporate available information on the pressure dependence of elastic constants taken from experiment or simulation. We apply our new theory to the example of the high-pressure cubic-tetragonal phase transition in strontium titanate, a model perovskite that has played a central role in the development of the theory of structural phase transitions. Armed with pressure-dependent elastic constants calculated by density-functional theory, we give an accurate description of recent high-precision experimental data and predict a number of elastic transition anomalies accessible to experiments.
Klushin, Leonid I; Skvortsov, Alexander M; Polotsky, Alexey A; Hsu, Hsiao-Ping; Binder, Kurt
2014-05-28
The coil-bridge transition in a self-avoiding lattice chain with one end fixed at height H above the attractive planar surface is investigated by theory and Monte Carlo simulation. We focus on the details of the first-order phase transition between the coil state at large height H ⩾ Htr and a bridge state at H ⩽ Htr, where Htr corresponds to the coil-bridge transition point. The equilibrium properties of the chain were calculated using the Monte Carlo pruned-enriched Rosenbluth method in the moderate adsorption regime at (H/Na)tr ⩽ 0.27 where N is the number of monomer units of linear size a. An analytical theory of the coil-bridge transition for lattice chains with excluded volume interactions is presented in this regime. The theory provides an excellent quantitative description of numerical results at all heights, 10 ⩽ H/a ⩽ 320 and all chain lengths 40 theory taking into account the effect of finite extensibility of the lattice chain in the strong adsorption regime at (H/Na)tr ⩾ 0.5 is presented. We discuss some unconventional properties of the coil-bridge transition: the absence of phase coexistence, two micro-phases involved in the bridge state, and abnormal behavior in the microcanonical ensemble.
Insight into Structural Phase Transitions from Density Functional Theory
Ruzsinszky, Adrienn
2014-03-01
Structural phase transitions caused by high pressure or temperature are very relevant in materials science. The high pressure transitions are essential to understand the interior of planets. Pressure or temperature induced phase transitions can be relevant to understand other phase transitions in strongly correlated systems or molecular crystals.Phase transitions are important also from the aspect of method development. Lower level density functionals, LSDA and GGAs all fail to predict the lattice parameters of different polymorphs and the phase transition parameters at the same time. At this time only nonlocal density functionals like HSE and RPA have been proved to resolve the geometry-energy dilemma to some extent in structural phase transitions. In this talk I will report new results from the MGGA_MS family of meta-GGAs and give an insight why this type of meta-GGAs can give a systematic improvement of the geometry and phase transition parameters together. I will also present results from the RPA and show a possible way to improve beyond RPA.
Theory of optical transitions in conjugated polymers. I. Ideal systems
Energy Technology Data Exchange (ETDEWEB)
Barford, William, E-mail: william.barford@chem.ox.ac.uk [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ (United Kingdom); Marcus, Max [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford OX1 3QZ (United Kingdom); Magdalen College, University of Oxford, Oxford OX1 4AU (United Kingdom)
2014-10-28
We describe a theory of linear optical transitions in conjugated polymers. The theory is based on three assumptions. The first is that the low-lying excited states of conjugated polymers are Frenkel excitons coupled to local normal modes, described by the Frenkel-Holstein model. Second, we assume that the relevant parameter regime is ℏω ≪ J, i.e., the adiabatic regime, and thus the Born-Oppenheimer factorization of the electronic and nuclear degrees of freedom is generally applicable. Finally, we assume that the Condon approximation is valid, i.e., the exciton-polaron wavefunction is essentially independent of the normal modes. Using these assumptions we derive an expression for an effective Huang-Rhys parameter for a chain (or chromophore) of N monomers, given by S(N) = S(1)/IPR, where S(1) is the Huang-Rhys parameter for an isolated monomer. IPR is the inverse participation ratio, defined by IPR = (∑{sub n}|Ψ{sub n}|{sup 4}){sup −1}, where Ψ{sub n} is the exciton center-of-mass wavefunction. Since the IPR is proportional to the spread of the exciton center-of-mass wavefunction, this is a key result, as it shows that S(N) decreases with chain length. As in molecules, in a polymer S(N) has two interpretations. First, ℏωS(N) is the relaxation energy of an excited state caused by its coupling to the normal modes. Second, S(N) appears in the definition of an effective Franck-Condon factor, F{sub 0v}(N) = S(N){sup v}exp ( − S(N))/v! for the vth vibronic manifold. We show that the 0 − 0 and 0 − 1 optical intensities are proportional to F{sub 00}(N) and F{sub 01}(N), respectively, and thus the ratio of the 0 − 1 to 0 − 0 absorption and emission intensities are proportional to S(N). These analytical results are checked by extensive DMRG calculations and found to be generally valid, particularly for emission. However, for large chain lengths higher-lying quasimomentum exciton states become degenerate with the lowest vibrational excitation of the
Interface Theories for (Asynchronously Communicating Modal I/O-Transition Systems
Directory of Open Access Journals (Sweden)
Sebastian S. Bauer
2011-01-01
Full Text Available Interface specifications play an important role in component-based software development. An interface theory is a formal framework supporting composition, refinement and compatibility of interface specifications. We present different interface theories which use modal I/O-transition systems as their underlying domain for interface specifications: synchronous interface theories, which employ a synchronous communication schema, as well as a novel interface theory for asynchronous communication where components communicate via FIFO-buffers.
Interface Theories for (A)synchronously Communicating Modal I/O-Transition Systems
Bauer, Sebastian S; Janisch, Stephan; 10.4204/EPTCS.46.1
2011-01-01
Interface specifications play an important role in component-based software development. An interface theory is a formal framework supporting composition, refinement and compatibility of interface specifications. We present different interface theories which use modal I/O-transition systems as their underlying domain for interface specifications: synchronous interface theories, which employ a synchronous communication schema, as well as a novel interface theory for asynchronous communication where components communicate via FIFO-buffers.
Non-Equilibrium Random Matrix Theory : Transition Probabilities
Pedro, Francisco Gil
2016-01-01
In this letter we present an analytic method for calculating the transition probability between two random Gaussian matrices with given eigenvalue spectra in the context of Dyson Brownian motion. We show that in the Coulomb gas language, in large $N$ limit, memory of the initial state is preserved in the form of a universal linear potential acting on the eigenvalues. We compute the likelihood of any given transition as a function of time, showing that as memory of the initial state is lost, transition probabilities converge to those of the static ensemble.
A Complete Approximation Theory for Weighted Transition Systems
DEFF Research Database (Denmark)
Hansen, Mikkel; Larsen, Kim Guldstrand; Mardare, Radu Iulian
2016-01-01
We propose a way of reasoning about minimal and maximal values of the weights of transitions in a weighted transition system (WTS). This perspective induces a notion of bisimulation that is coarser than the classic bisimulation: it relates states that exhibit transitions to bisimulation classes...... which allows us to prove the decidability of satisfiability and provide an algorithm for satisfiability checking. Last but not least, we identify a complete axiomatization for this logic, thus solving a long-standing open problem in this field. All our results are proven for a class of WTSs without...
Non-equilibrium random matrix theory. Transition probabilities
Energy Technology Data Exchange (ETDEWEB)
Pedro, Francisco Gil [Univ. Autonoma de Madrid (Spain). Dept. de Fisica Teorica; Westphal, Alexander [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Gruppe Theorie
2016-06-15
In this letter we present an analytic method for calculating the transition probability between two random Gaussian matrices with given eigenvalue spectra in the context of Dyson Brownian motion. We show that in the Coulomb gas language, in large N limit, memory of the initial state is preserved in the form of a universal linear potential acting on the eigenvalues. We compute the likelihood of any given transition as a function of time, showing that as memory of the initial state is lost, transition probabilities converge to those of the static ensemble.
Growing Open: The transition from QDA to Grounded Theory
Directory of Open Access Journals (Sweden)
Astrid Gynnild, Ph.D
2006-11-01
Full Text Available Doing a PhD can principally be carried out in three ways; firstly by applying existing theories on new data, secondly by theoretically comparing existing theories and thirdly by generating a new theory. Choice of approach of course depends on awareness and accessibility of alternatives. In essence, most PhD studies are exploratory journeys in a jungle of descriptive methodologies based on very uniform data. In this paper, the author elaborates the exploratory research process that subconsciously, and later consciously, required a shift from the initial QDA approach to grounded theory. The cutting point was discovering the multifaceted implications of the all-is-data dictum in GT.
Superstatistical random-matrix-theory approach to transition intensities in mixed systems.
Abul-Magd, A Y
2006-05-01
We study the fluctuation properties of transition intensities applying a recently proposed generalization of the random matrix theory, which is based on Beck and Cohen's superstatistics. We obtain an analytic expression for the distribution of the reduced transition probabilities that applies to systems undergoing a transition out of chaos. The obtained distribution fits the results of a previous nuclear shell model calculations for some electromagnetic transitions that deviate from the Porter-Thomas distribution. It agrees with the experimental reduced transition probabilities for the nucleus better than the commonly used chi(2) distribution.
Kim, Ki-Seok; Kim, Youngman; Ko, Yumi
2011-01-01
It is beyond the present techniques based on perturbation theory to reveal the nature of phase transitions in strongly interacting field theories. Recently, the holographic approach has provided us with an effective dual description, mapping strongly coupled conformal field theories to classical gravity theories. Resorting to the holographic superconductor model, we propose a general criterion for the nature of the superconducting phase transition based on effective interactions between vortices. We find "tricritical" points in terms of the chemical potential for U(1) charges and an effective Ginzburg-Landau parameter, where vortices do not interact to separate the second order (repulsive) from the first order (attractive) transitions. We interpret the first order transition as the Coleman-Weinberg mechanism, arguing that it is relevant to superconducting instabilities around quantum criticality.
The deconfinement phase transition in Yang-Mills theory with general Lie group G
Holland, K; Wiese, U J
2004-01-01
We present numerical results for the deconfinement phase transition in Sp(2) and Sp(3) Yang-Mills theories in (2+1)-D and (3+1)-D. We then make a conjecture on the order of this phase transition in Yang-Mills theories with general Lie groups G = SU(N), SO(N), Sp(N) and with exceptional groups G = G(2), F(4), E(6), E(7), E(8).
Theory of magnetic transition metal nanoclusters on surfaces
Energy Technology Data Exchange (ETDEWEB)
Lounis, S.
2007-04-17
This thesis is motivated by the quest for the understanding and the exploration of complex magnetism provided by atomic scale magnetic clusters deposited on surfaces or embedded in the bulk. Use is made of the density functional theory (DFT). Acting within this framework, we have developed and implemented the treatment of non-collinear magnetism into the Juelich version of the full-potential Korringa-Kohn-Rostoker Green Function (KKR-GF) method. Firstly, the method was applied to 3d transition-metal clusters on different ferromagnetic surfaces. Different types of magnetic clusters where selected. In order to investigate magnetic frustration due to competing interactions within the ad-cluster we considered a (001) oriented surface of fcc metals, a topology which usually does not lead to non-collinear magnetism. We tuned the strength of the magnetic coupling between the ad-clusters and the ferromagnetic surface by varying the substrate from the case of Ni(001) with a rather weak hybridization of the Ni d-states with the adatom d-states to the case of Fe{sub 3ML}/Cu(001) with a much stronger hybridization due to the larger extend of the Fe wavefunctions. On Ni(001), the interaction between the Cr- as well as the Mn-dimer adatoms is of antiferromagnetic nature, which is in competition with the interaction with the substrate atoms. After performing total energy calculations we find that for Cr-dimer the ground state is collinear whereas the Mn-dimer prefers the non-collinear configuration as ground state. Bigger clusters are found to be magnetically collinear. These calculations were extended to 3d multimers on Fe{sub 3ML}/Cu(001). All neighboring Cr(Mn) moments in the compact tetramer are antiferromagnetically aligned in-plane, with the directions slightly tilted towards (outwards from) the substrate to gain some exchange interaction energy. The second type of frustration was investigated employing a Ni(111) surface, a surface with a triangular lattice of atoms, were
Estimation and asymptotic theory for transition probabilities in Markov Renewal Multi–state models
Spitoni, C.; Verduijn, M.; Putter, H.
2012-01-01
In this paper we discuss estimation of transition probabilities for semi–Markov multi–state models. Non–parametric and semi–parametric estimators of the transition probabilities for a large class of models (forward going models) are proposed. Large sample theory is derived using the functional delta
On Mean-Field Theory of Quantum Phase Transition in Granular Superconductors
Simkin, M V
1996-01-01
In previous work on quantum phase transition in granular superconductors, where mean-field theory was used, an assumption was made that the order parameter as a function of the mean field is a convex up function. Though this is not always the case in phase transitions, this assumption must be verified, what is done in this article.
Statistical theory for transition and sustainment of the improved confinement state
Energy Technology Data Exchange (ETDEWEB)
Itoh, Sanae-I [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Itoh, Kimitaka [National Institute for Fusion Science, Toki 509-5292 (Japan); Yagi, Masatoshi [Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan); Toda, Shinichiro [National Institute for Fusion Science, Toki 509-5292 (Japan)
2004-05-01
The occurrence of stochastic transitions is investigated in the presence of triggers by turbulence noise and external events. The probability of observing the transition is calculated assuming that the global controlling parameters change in time. This is another important prediction of statistical theory in addition to the long time average. This explains the feature of transient response of the system with stochastic transitions. The interpretation of the experimental threshold database is discussed.
Theory of interfacial phase transitions in surfactant systems
Shukla, K. P.; Payandeh, B.; Robert, M.
1991-06-01
The spin-1 Ising model, which is equivalent to the three-component lattice gas model, is used to study wetting transitions in three-component surfactant systems consisting of an oil, water, and a nonionic surfactant. Phase equilibria, interfacial profiles, and interfacial tensions for three-phase equilibrium are determined in mean field approximation, for a wide range of temperature and interaction parameters. Surfactant interaction parameters are found to strongly influence interfacial tensions, reducing them in some cases to ultralow values. Interfacial tensions are used to determine whether the middle phase, rich in surfactant, wets or does not wet the interface between the oil-rich and water-rich phases. By varying temperature and interaction parameters, a wetting transition is located and found to be of the first order. Comparison is made with recent experimental results on wetting transitions in ternary surfactant systems.
Theory of photoinduced phase transitions in itinerant electron systems
Energy Technology Data Exchange (ETDEWEB)
Yonemitsu, Kenji [Institute for Molecular Science, Graduate University for Advanced Studies, Okazaki, Aichi 444-8585 (Japan)], E-mail: kxy@ims.ac.jp; Nasu, Keiichiro [Solid State Theory Division, Institute of Materials Structure Science, KEK, Graduate University for Advanced Studies, CREST JST, Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan)], E-mail: knasu@post.kek.jp
2008-08-15
Theoretical progress in the research of photoinduced phase transitions is reviewed with closely related experiments. After a brief introduction of stochastic evolution in statistical systems and domino effects in localized electron systems, we treat photoinduced dynamics in itinerant-electron systems. Relevant interactions are required in the models to describe the fast and ultrafast charge-lattice-coupled dynamics after photoexcitations. First, we discuss neutral-ionic transitions in the mixed-stack charge-transfer complex, TTF-CA. When induced by intrachain charge-transfer photoexcitations, the dynamics of the ionic-to-neutral transition are characterized by a threshold behavior, while those of the neutral-to-ionic transition by an almost linear behavior. The difference originates from the different electron correlations in the neutral and ionic phases. Second, we deal with halogen-bridged metal complexes, which show metal, Mott insulator, charge-density-wave, and charge-polarization phases. The latter two phases have different broken symmetries. The charge-density-wave to charge-polarization transition is much more easily achieved than the reverse transition. This is clarified by considering microscopic charge-transfer processes. The transition from the charge-density-wave to Mott insulator phases and that from the Mott insulator to metal phases proceed much faster than those between the low-symmetry phases. Next, we discuss ultrafast, inverse spin-Peierls transitions in an organic radical crystal and alkali-TCNQ from the viewpoint of intradimer and interdimer charge-transfer excitations. Then, we study photogenerated electrons in the quantum paraelectric perovskite, SrTiO{sub 3}, which are assumed to couple differently with soft-anharmonic phonons and breathing-type high-energy phonons. The different electron-phonon couplings result in two types of polarons, a 'super-paraelectric large polaron' with a quasi-global parity violation, and an &apos
Theory of photoinduced phase transitions in itinerant electron systems
Yonemitsu, Kenji; Nasu, Keiichiro
2008-08-01
Theoretical progress in the research of photoinduced phase transitions is reviewed with closely related experiments. After a brief introduction of stochastic evolution in statistical systems and domino effects in localized electron systems, we treat photoinduced dynamics in itinerant-electron systems. Relevant interactions are required in the models to describe the fast and ultrafast charge-lattice-coupled dynamics after photoexcitations. First, we discuss neutral-ionic transitions in the mixed-stack charge-transfer complex, TTF-CA. When induced by intrachain charge-transfer photoexcitations, the dynamics of the ionic-to-neutral transition are characterized by a threshold behavior, while those of the neutral-to-ionic transition by an almost linear behavior. The difference originates from the different electron correlations in the neutral and ionic phases. Second, we deal with halogen-bridged metal complexes, which show metal, Mott insulator, charge-density-wave, and charge-polarization phases. The latter two phases have different broken symmetries. The charge-density-wave to charge-polarization transition is much more easily achieved than the reverse transition. This is clarified by considering microscopic charge-transfer processes. The transition from the charge-density-wave to Mott insulator phases and that from the Mott insulator to metal phases proceed much faster than those between the low-symmetry phases. Next, we discuss ultrafast, inverse spin-Peierls transitions in an organic radical crystal and alkali-TCNQ from the viewpoint of intradimer and interdimer charge-transfer excitations. Then, we study photogenerated electrons in the quantum paraelectric perovskite, SrTiO 3, which are assumed to couple differently with soft-anharmonic phonons and breathing-type high-energy phonons. The different electron-phonon couplings result in two types of polarons, a “super-paraelectric large polaron” with a quasi-global parity violation, and an “off-center-type self
Order, disorder, and criticality advanced problems of phase transition theory
Holovatch, Yurij
2004-01-01
This book reviews some of the classic aspects in the theory of phasetransitions and critical phenomena, which has a longhistory. Recently, these aspects are attracting much attention due toessential new contributions. The topics presented in this bookinclude: mathematical theory of the Ising model; equilibrium andnon-equilibrium criticality of one-dimensional quantum spin chains;influence of structural disorder on the critical behaviour of thePotts model; criticality, fractality and multifractality of linkedpolymers; field-theoretical approaches in the superconducting phasetransitions.
Quantized Brans Dicke Theory: Phase Transition and Strong Coupling Limit
Pal, Sridip
2016-01-01
We show that Friedmann-Robertson-Walker (FRW) geometry with flat spatial section in quantized (Wheeler deWitt quantization) Brans Dicke (BD) theory reveals a rich phase structure owing to anomalous breaking of a classical symmetry, which maps the scale factor $a\\mapsto\\lambda a$ for some constant $\\lambda$. In the weak coupling ($\\omega$) limit, the theory goes from a symmetry preserving phase to a broken phase. The existence of phase boundary is an obstruction to another classical symmetry [arXiv:gr-qc/9902083] (which relates two BD theory with different coupling) admitted by BD theory with scale invariant matter content i.e $T^{\\mu}{}_{\\mu}=0$. Classically, this prohibits the BD theory to reduce to General Relativity (GR) for scale invariant matter content. We show that strong coupling limit of BD and GR both preserves the symmetry involving scale factor. We also show that with a scale invariant matter content (radiation i.e $P=\\frac{1}{3}\\rho$), the quantized BD theory does reduce to GR as $\\omega\\rightarr...
Applying Career Development Theories to the School-to-Work Transition Process.
Lent, Robert W.; Worthington, Roger L.
1999-01-01
Career development theories do not typically highlight their relevance to the school-to-work transition process. This issue features articles that examine how several prominent career development theories (person-environment fit, social learning, developmental, and social cognitive) can be brought to bear on this process. Three discussants assess…
Centering Theory, transitions and referent marking in the corpus of the written Serbian language
Directory of Open Access Journals (Sweden)
Trnavac Radoslava
2015-01-01
Full Text Available The aim of the paper is to map various types of anaphor to the centering transitions in the corpus of Serbian newspaper articles. Centering Theory (WALKER, JOSHI ET AL. 1998 is a theory of local coherence in which four types of transitions are used as parameters of coherence. As is hypothesized in the previous literature based on various languages, the CONTINUE transition is mostly characterized by a minimal form (a zero form of the topic, while the SMOOTH and ROUGH shifts are found with a full noun phrase topic. The analysis shows that the “Ordering Rule” of Centering Theory is not fully followed in the written corpus of the Serbian language since SMOOTH SHIFT has been identified as a prevalent type of transition in the corpus. The following two reasons were identified for that: (1 the genre of the newspaper articles, and (2 the way clauses are combined within a complex sentence in the Serbian written corpus.
New dualities from orientifold transitions Part II: string theory
García-Etxebarria, Iñaki; Heidenreich, Ben; Wrase, Timm
2013-10-01
We present a string theoretical description, given in terms of branes and orientifolds wrapping vanishing cycles, of the dual pairs of gauge theories analyzed in [1]. Based on the resulting construction we argue that the duality that we observe in field theory is inherited from S-duality of type IIB string theory. We analyze in detail the complex cone over the zeroth del Pezzo surface and discuss an infinite family of orbifolds of flat space. For the del Pezzo case we describe the system in terms of large volume objects, and show that in this language the duality can be understood from the strongly coupled behavior of the O7+ plane, which we analyze using simple F-theory considerations. For all cases we also give a different argument based on the existence of appropriate torsional components of the 3-form flux lattice. Along the way we clarify some aspects of the description of orientifolds in the derived category of coherent sheaves, and in particular we discuss the important role played by exotic orientifolds — ordinary orientifolds composed with auto-equivalences of the category — when describing orientifolds of ordinary quiver gauge theories.
Quantum criticality at the Anderson transition: A typical medium theory perspective
Mahmoudian, Samiyeh; Tang, Shao; Dobrosavljević, Vladimir
2015-10-01
We present a complete analytical and numerical solution of the typical medium theory (TMT) for the Anderson metal-insulator transition. This approach self-consistently calculates the typical amplitude of the electronic wave functions, thus representing the conceptually simplest order-parameter theory for the Anderson transition. We identify all possible universality classes for the critical behavior, which can be found within such a mean-field approach. This provides insights into how interaction-induced renormalizations of the disorder potential may produce qualitative modifications of the critical behavior. We also formulate a simplified description of the leading critical behavior, thus obtaining an effective Landau theory for Anderson localization.
Successive phase transitions and kink solutions in ϕ(8), ϕ(10), and ϕ(12) field theories.
Khare, Avinash; Christov, Ivan C; Saxena, Avadh
2014-08-01
We obtain exact solutions for kinks in ϕ(8), ϕ(10), and ϕ(12) field theories with degenerate minima, which can describe a second-order phase transition followed by a first-order one, a succession of two first-order phase transitions and a second-order phase transition followed by two first-order phase transitions, respectively. Such phase transitions are known to occur in ferroelastic and ferroelectric crystals and in meson physics. In particular, we find that the higher-order field theories have kink solutions with algebraically decaying tails and also asymmetric cases with mixed exponential-algebraic tail decay, unlike the lower-order ϕ(4) and ϕ(6) theories. Additionally, we construct distinct kinks with equal energies in all three field theories considered, and we show the coexistence of up to three distinct kinks (for a ϕ(12) potential with six degenerate minima). We also summarize phonon dispersion relations for these systems, showing that the higher-order field theories have specific cases in which only nonlinear phonons are allowed. For the ϕ(10) field theory, which is a quasiexactly solvable model akin to ϕ(6), we are also able to obtain three analytical solutions for the classical free energy as well as the probability distribution function in the thermodynamic limit.
Quantitative analysis of non-equilibrium phase transition process by the catastrophe theory
Liang, Xiao; Wu, Jiu Hui; Zhong, H. B.
2017-08-01
Catastrophe theory is a highly generalized mathematical theory that summarizes the rules of non-equilibrium phase transition by several catastrophe models. This paper investigates the general non-equilibrium phase transition process quantitatively using catastrophe theory for the first time, to our knowledge. First, a new approach is proposed by combining the catastrophe theory with dimensionless analysis. Second, the new approach is applied to two classic examples: one is the turbulent phase transition and the other is the bottleneck effect of particle flow. For the turbulence phase transition process, the quantitative relationships are obtained. Comparing with Kolmogorov's turbulent theory, the new method proposed in this paper is able to evaluate not only the complete turbulence condition but also the development of turbulence, and Kolmogorov's turbulent theory is only a special case of our results by this new approach. For the particle flow bottleneck effect, the results obtained by this new method correspond with the empirical formulated results. Therefore, the proposed method can solve non-equilibrium phase transition process problems and has the potential to extend to fluid, aerodynamics, and so forth.
Gender inequalities from the demographic perspective
Directory of Open Access Journals (Sweden)
Devedžić Mirjana
2006-01-01
Full Text Available The paper analyzes the meaning of the phrase "the woman’s status in the society" that is recognized in demography as an important cultural factor of demographic development and transitional changes. The analysis indicates qualitative shifts in the woman’s status and simultaneously reveals its importance at present, not only in traditional, but also in modern and developed societies. On the other hand, it explains the importance of sex as a biodemographic determinant, and introduces the concept of gender that sheds another light on the concepts of sex and woman’s status in the society and integrates them. Gender regimes that subsume the inferiority of women in public and private social structures are examined from demographic perspective, albeit only in those phenomenological aspects that can be supported by demographic research, theories, and analyses. To this end, the paper analyzes the effects of strengthening gender equalities on the fertility and mortality transitions, the gender’s impact on the population distribution by sex in South Asian countries, and highlights the key role of gender in interpreting certain social and economic structures. It also stresses the establishing of gender equality as an important element of population policies. The global dimension of the patriarchal society is illustrated through a series of examples of demographic phenomena from various societies. Gender regimes underlie all of these phenomena. The paper puts foreword certain theoretical hypotheses about gender inequalities, and finds their connections with demographic behaviors and demographic indicators. Finally, it summarizes the role of demography in gender (inequality research and the demographic perspective of the way and the speed the demographic equality is being established. Demography is seen as an irreplaceable discipline in examining gender inequalities, especially at the global level. With the advance of qualitative methods in demography
Phase transition of charged Black Holes in Brans-Dicke theory through geometrical thermodynamics
Hendi, S H; Panah, B Eslam; Armanfard, Z
2015-01-01
In this paper, we take into account black hole solutions of Brans-Dicke-Maxwell theory and investigate their stability and phase transition points. We apply the concept of geometry in thermodynamics to obtain phase transition points and compare its results with those of calculated in canonical ensemble through heat capacity. We show that these black holes enjoy second order phase transitions. We also show that there is a lower bound for the horizon radius of physical charged black holes in Brans-Dicke theory which is originated from restrictions of positivity of temperature. In addition, we find that employing specific thermodynamical metric in the context of geometrical thermodynamics yields divergencies for thermodynamical Ricci scalar in places of phase transitions. It will be pointed out that due to characteristics behavior of thermodynamical Ricci scalar around its divergence points, one is able to distinguish the physical limitation point from the phase transitions.
Dynamic aspect of the chiral phase transition in the mode coupling theory
Ohnishi, K; Ohta, K
2005-01-01
We analyze the dynamic aspect of the chiral phase transition. We apply the mode coupling theory to the linear sigma model and derive the kinetic equation for the chiral phase transition. We challenge Hohenberg and Halperin's classification scheme of dynamic critical phenomena in which the dynamic universality class of the chiral phase transition has been identified with that of the antiferromagnet. We point out a crucial difference between the chiral dynamics and the antiferromagnet system. We also calculate the dynamic critical exponent for the chiral phase transition. Our result is $z=1-\\eta/2\\cong 0.98$ which is contrasted with $z=d/2=1.5$ of the antiferromagnet.
Black holes and flop transitions in M-theory on Calabi-Yau 3-folds
Gaida, Ingo; Mahapatra, Swapna; Mohaupt, Thomas; Sabra, Wafic A.
1999-02-01
We present five-dimensional extreme black hole solutions of M-theory compactified on Calabi-Yau 3-folds and study these solutions in the context of flop transitions in the extended Kähler cone. In particular, we consider a specific model and present black hole solutions, breaking half of N = 2 supersymmetry, in two regions of the extended Kähler cone, which are connected by a flop transition. The conditions necessary to match both solutions at the flop transition are analysed. Finally, we also discuss the conditions to obtain massless black holes at the flop transition.
Applying the Happenstance Learning Theory to Involuntary Career Transitions
Krumboltz, John D.; Foley, Pamela F.; Cotter, Elizabeth W.
2013-01-01
The happenstance learning theory (HLT) proposes a model of career counseling that helps clients to build more satisfying personal and work lives. Although reflective listening remains an essential part of the process, HLT is an action-oriented approach to helping clients to both create and benefit from unplanned events. Success is measured not by…
Relational Processes in Career Transition: Extending Theory, Research, and Practice
Motulsky, Sue L.
2010-01-01
A growing body of work in relational theory and career decision making explores how relational processes, not just people's relationships but more broadly their connections to self, others, and society, inform career development and counseling. This article presents the results of a qualitative research study of midlife women in career transition…
Mackeprang, Kasper; Kjaergaard, Henrik G.
2017-04-01
The local mode perturbation theory (LMPT) model was developed to improve the description of hydrogen bonded XH-stretching transitions, where X is typically O or N. We present a modified version of the LMPT model to extend its application from hydrated bimolecular complexes to hydrogen bonded bimolecular complexes with donors such as alcohols, amines and acids. We have applied the modified model to a series of complexes of different hydrogen bond type and complex energy. We found that the differences between local mode (LM) and LMPT calculated fundamental XH-stretching transition wavenumbers and oscillator strengths were correlated with the strength of the hydrogen bond. Overall, we have found that the LMPT model in most cases predicts transition wavenumbers within 20 cm-1 of the experimental values.
A Spin(7) Conifold Transition in Type IIB as an F-theory Flop
Tan, M C; Teo, Edward
2004-01-01
We consider type IIB string theory compactified on an 8-dimensional Spin(7) manifold with N D5-branes, undergoing a conifold transition to a geometry with no branes and N units of dual 3-form RR flux through appropriate 3-cycles. We show that at {\\it constant} IIB coupling, in the limit of large N and finite 't Hooft coupling, this conifold transition can be lifted to a purely geometric S^5 flop in the 11-dimensional space of an equivalent F-theory without branes and fluxes. The S^5 flop in this equivalent F-theory is a higher-dimensional analogue of the S^3 flop in M-theory on a G_2 manifold discovered by Atiyah et al., albeit resulting in a theory with {\\cal N}=1 in d=2 instead of d=4.
Khare, Avinash; Saxena, Avadh
2014-01-01
We obtain exact solutions for kinks in $\\phi^{8}$, $\\phi^{10}$ and $\\phi^{12}$ field theories with degenerate minima, which can describe a second-order phase transition followed by a first-order one, a succession of two first-order phase transitions and a second-order phase transition followed by two first-order phase transitions, respectively. Such phase transitions are known to occur in ferroelastic and ferroelectric crystals and in meson physics. In particular, we find that the higher-order field theories have kink solutions with algebraically-decaying tails and also asymmetric cases with mixed exponential-algebraic tail decay, unlike the lower-order $\\phi^4$ and $\\phi^6$ theories. Additionally, we construct distinct kinks with equal energies in all three field theories considered, and we show the co-existence of up to three distinct kinks (for a $\\phi^{12}$ potential with six degenerate minima). We also summarize phonon dispersion relations for these systems, showing that the higher-order field theories h...
Microscopic theory of superconductivity near a Lifshitz transition
Mishra, Vivek; Maier, Thomas; Scalapino, Doug
Observation of robust superconductivity in some of the iron based superconductors in the vicinity of a Lifshitz point has attracted many theoretical and experimental studies. The majority of these studies have been phenomenological. Here we discuss a microscopic treatment of the pairing mechanism for a bilayer Hubbard model, which goes through a Lifshitz transition. We study pairing driven by spin-fluctuations by solving the strong coupling Eliashberg equations and make a systematic comparison of the results with non-perturbative dynamical cluster quantum Monte Carlo calculations. Our findings are quite general and we will discuss their application to some of the iron based superconductors. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy.
Topological phase transitions in Calabi-Yau compactifications of M-theory
Energy Technology Data Exchange (ETDEWEB)
Saueressig, F. [Theoretisch-Physikalisches Institut, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, 07743 Jena (Germany)
2005-01-14
In this thesis we construct five-dimensional gauged supergravity actions which describe flop and conifold transitions in M-theory compactified on Calabi-Yau threefolds. While the vector multiplet sector is determined exactly, we use the Wolf spaces X(1+N) = (U(1+N,2))/(U(1+N)xU(2)) to model the universal hypermultiplet together with N charged hypermultiplets corresponding to winding states of M2-branes. After specifying the hypermultiplet sector the actions are uniquely determined by M-theory. As an application we consider five-dimensional Kasner cosmologies. Including the dynamics of the winding modes, we find smooth cosmological solutions which undergo flop and conifold transitions. Instead of the usual runaway behavior the scalar fields of these solutions generically stabilize in the transition region where they oscillate around the transition locus. The scalar potential thereby induces short episodes of accelerated expansion in the space-time. (Abstract Copyright [2005], Wiley Periodicals, Inc.)
Turning reduced density matrix theory into a practical tool for studying the Mott transition
Pernal, Katarzyna
2015-11-01
Strongly correlated systems pose a challenge for theoretical methods based on an independent electron approximation. Such methods struggle to predict a nonzero gap in Mott insulators or to capture the correct physics of the insulator-to-metal phase transition in strongly correlated materials. In a recent paper by Shinohara et al (2015 New J. Phys. 17 093038) it is shown that strongly correlated materials and correct descriptions of their phase transitions are within the reach of reduced density matrix functional theory (RDMFT) approximations. For a doping-induced phase transition, not only is a satisfactory agreement with experimental spectra found for NiO but it is also shown that the physical picture of the observed Mott transition stays in line with more computationally demanding many-body theories. This is an important step toward providing an RDMFT-based computation tool for studying strongly correlated materials.
Efficacy of a Transition Theory-Based Discharge Planning Program for Childhood Asthma Management.
Ekim, Ayfer; Ocakci, Ayse Ferda
2016-02-01
This study tested the efficacy of a nurse-led discharge planning program for childhood asthma management, based on transition theory. A quasi-experimental design was used. The sample comprised 120 children with asthma and their parents (intervention group n = 60, control group n = 60). The asthma management self-efficacy perception level of parents in the intervention group increased significantly and the number of triggers their children were exposed to at home was reduced by 60.8%. The rates of admission to emergency departments and unscheduled outpatient visits were significantly lower in the intervention group compared with the control group. Transition theory-based nursing interventions can provide successful outcomes on childhood asthma management. Transition theory-based discharge planning program can guide nursing interventions to standardize care of the child with asthma. Combining care at home with hospital care strengthens ongoing qualified asthma management. © 2015 NANDA International, Inc.
Phase transition for black holes in dilatonic Einstein-Gauss-Bonnet theory of gravitation
Khimphun, Sunly; Lee, Bum-Hoon; Lee, Wonwoo
2016-11-01
We study the thermodynamic properties of a black hole and the Hawking-Page phase transition in the asymptotically anti-de Sitter spacetime in the dilatonic Einstein-Gauss-Bonnet theory of gravitation. We show how the higher-order curvature terms can influence both the thermodynamic properties and the phase transition. We evaluate both heat capacity and free energy difference to determine the local and global thermodynamic stabilities, respectively. We find that the phase transition occurs from the thermal anti-de Sitter to a small spherical black hole geometry and occurs to a hyperbolic black hole geometry in the (dilatonic) Einstein-Gauss-Bonnet theory of gravitation unlike those in Einstein's theory of gravitation.
Phase transition for black holes in Dilatonic Einstein-Gauss-Bonnet theory of gravitation
Khimphun, Sunly; Lee, Wonwoo
2016-01-01
We study the thermodynamic properties of a black hole and the Hawking-Page phase transition in the asymptotically anti-de Sitter spacetime in the Dilatonic Einstein-Gauss-Bonnet theory of gravitation. We show how the higher-order curvature terms can influence both the thermodynamic properties and the phase transition. We evaluate both heat capacity and free energy difference to determine the local and global thermodynamic stabilities, respectively. We show that the phase transition occurs from the thermal anti-de Sitter to a small spherical black hole geometry and occurs to a large hyperbolic black hole geometry in the (Dilatonic) Einstein-Gauss-Bonnet theory of gravitation unlike those in Einstein's theory of gravitation.
Mercure, Jean-Francois
2012-01-01
This paper presents a general theory that aims at explaining timescales observed empirically in technology transitions and predicting those of future transitions. This framework is used further to derive a theory for exploring the dynamics that underlie the complex phenomenon of irreversible and path dependent price or policy induced efficiency changes. Technology transitions are known to follow patterns well described by logistic functions, which should more rigorously be modelled mathematically using the Lotka-Volterra family of differential equations, originally developed to described the population growth of competing species. The dynamic evolution of technology has also been described theoretically using evolutionary dynamics similar to that observed in nature. The theory presented here joins both approaches and presents a methodology for predicting changeover time constants in order to describe real systems of competing technologies. The problem of price or policy induced efficiency changes becomes natu...
Piomelli, Ugo; Zang, Thomas A.; Speziale, Charles G.; Lund, Thomas S.
1990-01-01
An eddy viscosity model based on the renormalization group theory of Yakhot and Orszag (1986) is applied to the large-eddy simulation of transition in a flat-plate boundary layer. The simulation predicts with satisfactory accuracy the mean velocity and Reynolds stress profiles, as well as the development of the important scales of motion. The evolution of the structures characteristic of the nonlinear stages of transition is also predicted reasonably well.
Public Transit Subsidy: from the Economics of Welfare to the Theory of Incentives
Fabbri, D.
1995-01-01
Public Transit is publicly managed almost all over Europe. Public intervention in this sector is due to market failures: economies of scale and misperceptions of social and private costs may cause an insufficient supply of transit services. These arguments have been thouroughly analyzed within the standard welfarist approach to the theory and practice of subsidization. Ramsey rules and cost-benefit analysis emerged as useful devices for the definition of subsidy allocation. However remedies t...
Planet formation in transition disks: Modeling, spectroscopy, and theory
Liskowsky, Joseph Paul
An important field of modern astronomy is the study of planets. Literally for millennia, careful observers of the night sky have tracked these 'wanderers', with their peculiar motions initiating avenues of inquiry not able to elucidated by a study of the stars alone: we have discovered that the planets (as well as Earth) orbit the sun and that the stars are so far away, even their relative positions do not seem to shift perceptibly when Earth's position moves hundreds of millions of miles. With the advent of the telescope, and subsequent improvements upon it over the course of centuries, accelerating to the dramatically immense telescopes available today and those on the horizon, we have been able to continuously probe farther and in more detail than the previous generation of scientists and telescopes allowed. Now, we are just entering the time when detection of planets outside of our own solar system has become possible, and we have found that planets are extraordinarily common in the galaxy (and by extrapolation, the universe). At the time of this document's composition, there are several thousand such examples of planets around other stars (being dubbed 'exoplanets'). We have discovered that planets are plentiful, but multiple open questions remain which are relevant to this work: How do planets form and, when a planet does form from its circumstellar envelope, what are the important processes that influence its formation? This work adds to the understanding of circumstellar disks, the intermediate stage between a cold collapsing cloud (of gas and dust) and a mature planetary system. Specifically, we study circumstellar disks in an evolved state termed 'transition disks'. This state corresponds to a time period where the dust in the disk has either undergone grain growth—where the microscopic grains have clumped together to form far fewer dust particles of much higher mass, or the inner portion (or an inner annulus) of the disk has lost a large amount of gas
Time-dependent renormalized Redfield theory II for off-diagonal transition in reduced density matrix
Kimura, Akihiro
2016-09-01
In our previous letter (Kimura, 2016), we constructed time-dependent renormalized Redfield theory (TRRT) only for diagonal transition in a reduced density matrix. In this letter, we formulate the general expression for off-diagonal transition in the reduced density matrix. We discuss the applicability of TRRT by numerically comparing the dependencies on the energy gap of the exciton relaxation rate by using the TRRT and the modified Redfield theory (MRT). In particular, we roughly show that TRRT improves MRT for the detailed balance about the excitation energy transfer reaction.
Random matrix theory approach to vibrations near the jamming transition
Beltukov, Y. M.
2015-03-01
It has been shown that the dynamical matrix M describing harmonic oscillations in granular media can be represented in the form M = AA T, where the rows of the matrix A correspond to the degrees of freedom of individual granules and its columns correspond to elastic contacts between granules. Such a representation of the dynamical matrix makes it possible to estimate the density of vibrational states with the use of the random matrix theory. The found density of vibrational states is approximately constant in a wide frequency range ω- < ω < ω+, which is determined by the ratio of the number of degrees of freedom to the total number of contacts in the system, which is in good agreement with the results of the numerical experiments.
Pérez-Mercader, J
1993-01-01
We define an entropy for a quantum field theory by combining quantum fluctuations, scaling and the maximum entropy concept. This entropy has different behavior in asymptotically free and non--asymptotically free theories. We find that the transition between the two regimes (from the asymptotically free to the non--asymptotically free) takes place via a continuous phase transition. For asymptotically free theories there exist regimes where the ``temperatures" are negative. In asymptotically free theories there exist maser--like states mostly in the infrared; furthermore, as one goes into the ultraviolet and more matter states contribute to quantum processes, the quantum field system can shed entropy and cause the formation of thermodynamically stable {\\it entropy--ordered} states. It is shown how the known heavier quarks can be thus described.
Calaminici, Patrizia; Janetzko, Florian; Köster, Andreas M; Mejia-Olvera, Roberto; Zuniga-Gutierrez, Bernardo
2007-01-28
Density functional theory optimized basis sets for gradient corrected functionals for 3d transition metal atoms are presented. Double zeta valence polarization and triple zeta valence polarization basis sets are optimized with the PW86 functional. The performance of the newly optimized basis sets is tested in atomic and molecular calculations. Excitation energies of 3d transition metal atoms, as well as electronic configurations, structural parameters, dissociation energies, and harmonic vibrational frequencies of a large number of molecules containing 3d transition metal elements, are presented. The obtained results are compared with available experimental data as well as with other theoretical data from the literature.
Kota, V K B
2015-01-01
Embedded random matrix ensembles are generic models for describing statistical properties of finite isolated interacting quantum many-particle systems. For the simplest spinless systems, with say $m$ particles in $N$ single particle states and interacting via $k$-body interactions, we have EGUE($k$) and the embedding algebra is $U(N)$. A finite quantum system, induced by a transition operator, makes transitions from its states to the states of the same system or to those of another system. Examples are electromagnetic transitions (same initial and final systems), nuclear beta and double beta decay (different initial and final systems), particle addition to/removal from a given system and so on. Towards developing a complete statistical theory for transition strength densities, we have derived formulas for lower order bivariate moments of the strength densities generated by a variety of transition operators. For a spinless fermion system, using EGUE($k$) representation for Hamiltonian and an independent EGUE($...
Energy Technology Data Exchange (ETDEWEB)
Zinn-Justin, J
2003-08-01
In the quantum field theory the problem of infinite values has been solved empirically through a method called renormalization, this method is satisfying only in the framework of renormalization group. It is in the domain of statistical physics and continuous phase transitions that these issues are the easiest to discuss. Within the framework of a course in theoretical physics the author introduces the notions of continuous limits and universality in stochastic systems operating with a high number of freedom degrees. It is shown that quasi-Gaussian and mean field approximation are unable to describe phase transitions in a satisfying manner. A new concept is required: it is the notion of renormalization group whose fixed points allow us to understand universality beyond mean field. The renormalization group implies the idea that long distance correlations near the transition temperature might be described by a statistical field theory that is a quantum field in imaginary time. Various forms of renormalization group equations are presented and solved in particular boundary limits, namely for fields with high numbers of components near the dimensions 4 and 2. The particular case of exact renormalization group is also introduced. (A.C.)
Ndahindwa, Vedaste; Kamanzi, Collins; Semakula, Muhammed; Abalikumwe, François; Hedt-Gauthier, Bethany; Thomson, Dana R
2014-12-13
Major improvements to Rwanda's health system, infrastructure, and social programs over the last decade have led to a rapid fertility transition unique from other African countries. The total fertility rate fell from 6.1 in 2005 to 4.6 in 2010, with a 3-fold increase in contraceptive usage. Despite this rapid national decline, many women still have large numbers of children. This study investigates predictors of fertility during this fertility transition to inform policies that improve individuals' reproductive health and guide national development. We used Poisson regression to separately model number of children born to ever married/cohabitated women (n = 8,309) and never married women (n = 1,220) age 15 to 49 based on 2010 Rwanda Demographic and Health Survey data. We used backward stepwise regression with a time offset to identify individual and household factors associated with woman's fertility level, accounting for sampling weights, clustering, and stratification. In ever married/cohabitating women, high fertility was significantly associated (p fertility in ever married/cohabitating women was associated with women's education (higher versus no education: IRR = 0.66), household wealth (highest versus lowest quintile: IRR = 0.93), and delayed sexual debut (25+ versus 8-18 years: IRR = 0.49). In never married women, low fertility was associated with education (higher versus no education: IRR = 0.22), household wealth (highest versus lowest quintile: IRR = 0.58), delayed sexual debut (25-49 versus 8-18 years: IRR = 0.43), and having an unmet need for contraception (IRR = 0.69). Although the study design does not allow causal conclusions, these results suggest several strategies to further reduce Rwanda's national fertility rate and support families to achieve their desired fertility. Strategies include policies and programs that promote delayed sexual debut via educational and economic opportunities for women, improved access to reproductive health information
Directory of Open Access Journals (Sweden)
Mahboobeh Namnabati
2017-01-01
Full Text Available Background: Infant's transition is a challenge for parents and the health system that requires ongoing assessment and management to improve each newborn`s growth and development. The purpose of this study was to explore the management of infant` transition from neonatal intensive care unit (NICU to home.Materials and Methods: We used a grounded theory study to explore and describe the management of infants’ transition from the NICU to the home. Interviews were conducted with 31 professionals and 20 family members, and participant observations were made in hospitals, clinics, and one physician office. MAXQDA was utilized for coding and categorizing data.Results: The theory illustrated six phenomena: An unexpected separation; A crisis situation; Mother-infant rebonding; Protection of the infant’s health; Promotion of growth and development; and Inadequate management causing disability. Together, these formed a three-phase process consisting of: A threat to the infant's life, Efforts to save the infant's life, and Continuation of life. Conclusion: Development of the theory of infants transition provides a three phases process ( A threat to the infant’s life, Efforts to save the infant’s life, and Continuation of life, that can yield guidelines to manage the infant` transition in prevent mother–infant separation, support parents in their role as primary caregivers, and follow up with individual home visits by nurses.
Income Attainment During Transformation Processes : A Meta-Analysis of the Market Transition Theory
Verhoeven, Willem-Jan; Jansen, Wim; Dessens, Jos
2005-01-01
The changing communist regime in China and the ‘velvet’ revolutions in Central and Eastern Europe (CEE) have provided an opportunity to investigate trends in income attainment during processes of transformation. Nee (1989) formulated the market transition theory, which indicates the main determinant
Mean Field Theory, Ginzburg Criterion, and Marginal Dimensionality of Phase-Transitions
DEFF Research Database (Denmark)
Als-Nielsen, Jens Aage; Birgenau, R. J.
1977-01-01
By applying a real space version of the Ginzburg criterion, the role of fluctuations and thence the self‐consistency of mean field theory are assessed in a simple fashion for a variety of phase transitions. It is shown that in using this approach the concept of ’’marginal dimensionality’’ emerges...
Applying Theories of Person-Environment Fit to the Transition from School to Work.
Swanson, Jane L.; Fouad, Nadya A.
1999-01-01
Describes potential contributions of theories of person-environment fit to understanding of the transition from school to work. Provides specific implications for integrating these concepts into school-to-work programs including: students need to spend time in exploration that leads to self-knowledge; programs should teach elements of…
Wigner's dynamical transition state theory in phase space : classical and quantum
Waalkens, Holger; Schubert, Roman; Wiggins, Stephen
2008-01-01
We develop Wigner's approach to a dynamical transition state theory in phase space in both the classical and quantum mechanical settings. The key to our development is the construction of a normal form for describing the dynamics in the neighbourhood of a specific type of saddle point that governs t
Income Attainment During Transformation Processes : A Meta-Analysis of the Market Transition Theory
Verhoeven, Willem-Jan; Jansen, Wim; Dessens, Jos
2005-01-01
The changing communist regime in China and the ‘velvet’ revolutions in Central and Eastern Europe (CEE) have provided an opportunity to investigate trends in income attainment during processes of transformation. Nee (1989) formulated the market transition theory, which indicates the main
Chiral perturbation theory study of the axial $N\\to\\Delta(1232)$ transition
Geng, L S; Alvarez-Ruso, L; Vacas, M J Vicente
2008-01-01
We have performed a theoretical study of the axial Nucleon to Delta(1232) ($N\\to\\Delta$) transition form factors up to one-loop order in covariant baryon chiral perturbation theory within a formalism in which the unphysical spin-1/2 components of the $\\Delta$ fields are decoupled.
Simulations Of Field Theories In World Line Representation (higgs Model, Phase Transition)
Pap, A L
1998-01-01
We have studied phase transition of systems of random paths numerically. Random paths have generated considerable interest for three reasons. First: Random paths play a central role in the investigation of polymers and proteins. Second: They also serve as a model for the more complicated surfaces and higher dimensional manifolds which are necessary ingredients of string theories and quantum gravity...
van Scheppingen, M.A.; Jackson, J.J.; Specht, J.; Hutteman, R.; Denissen, J.J.A.; Bleidorn, Wiebke
2016-01-01
Social investment theory (SIT) proposes that the transition to parenthood triggers positive personality trait change in early adulthood. Using data from a representative sample of first-time parents compared to nonparents, the results of rigorous tests do not support the propositions of SIT. Specifi
Theory for Explaining and Comparing the Dynamics of Education in Transitional Processes
van der Walt, Johannes L.
2016-01-01
Countries all over the world find themselves in the throes of revolution, change, transition or transformation. Because of the complexities of these momentous events, it is no simple matter to describe and evaluate them. This paper suggests that comparative educationists apply a combination of three theories as a lens through which such national…
Application of Self-Efficacy Theory to the Transition from School to Work.
Strauser, David R.; Waldrop, Drenna G.; Jenkins, William M.
1998-01-01
To facilitate the school-to-work transition of students with disabilities, psychosocial factors such as those identified in Bandura's theory of self-efficacy should be considered. Performance accomplishment, vicarious experiences, verbal persuasion, and emotional arousal can be used to increase success. (SK)
Thermal isomerization of azobenzenes: on the performance of Eyring transition state theory
Rietze, Clemens; Titov, Evgenii; Lindner, Steven; Saalfrank, Peter
2017-08-01
The thermal Z\\to E (back-)isomerization of azobenzenes is a prototypical reaction occurring in molecular switches. It has been studied for decades, yet its kinetics is not fully understood. In this paper, quantum chemical calculations are performed to model the kinetics of an experimental benchmark system, where a modified azobenzene (AzoBiPyB) is embedded in a metal-organic framework (MOF). The molecule can be switched thermally from cis to trans, under solvent-free conditions. We critically test the validity of Eyring transition state theory for this reaction. As previously found for other azobenzenes (albeit in solution), good agreement between theory and experiment emerges for activation energies and activation free energies, already at a comparatively simple level of theory, B3LYP/6-31G* including dispersion corrections. However, theoretical Arrhenius prefactors and activation entropies are in qualitiative disagreement with experiment. Several factors are discussed that may have an influence on activation entropies, among them dynamical and geometric constraints (imposed by the MOF). For a simpler model—Z\\to E isomerization in azobenzene—a systematic test of quantum chemical methods from both density functional theory and wavefunction theory is carried out in the context of Eyring theory. Also, the effect of anharmonicities on activation entropies is discussed for this model system. Our work highlights capabilities and shortcomings of Eyring transition state theory and quantum chemical methods, when applied for the Z\\to E (back-)isomerization of azobenzenes under solvent-free conditions.
Phase transition of charged Black Holes in Brans-Dicke theory through geometrical thermodynamics
Hendi, S. H.; Panahiyan, S.; Panah, B. Eslam; Armanfard, Z.
2016-07-01
In this paper, we take into account black hole solutions of Brans-Dicke-Maxwell theory and investigate their stability and phase transition points. We apply the concept of geometry in thermodynamics to obtain phase transition points and compare its results with those, calculated in the canonical ensemble through heat capacity. We show that these black holes enjoy second order phase transitions. We also show that there is a lower bound for the horizon radius of physical charged black holes in Brans-Dicke theory, which originates from restrictions of positivity of temperature. In addition, we find that employing a specific thermodynamical metric in the context of geometrical thermodynamics yields divergencies for the thermodynamical Ricci scalar in places of the phase transitions. It will be pointed out that due to the characteristic behavior of the thermodynamical Ricci scalar around its divergence points, one is able to distinguish the physical limitation point from the phase transitions. In addition, the free energy of these black holes will be obtained and its behavior will be investigated. It will be shown that the behavior of the free energy in the place where the heat capacity diverges demonstrates second order phase transition characteristics.
Large-Scale Density Functional Theory Transition State Searching in Enzymes.
Lever, Greg; Cole, Daniel J; Lonsdale, Richard; Ranaghan, Kara E; Wales, David J; Mulholland, Adrian J; Skylaris, Chris-Kriton; Payne, Mike C
2014-11-06
Linear-scaling quantum mechanical density functional theory calculations have been applied to study the rearrangement of chorismate to prephenate in large-scale models of the Bacillus subtilis chorismate mutase enzyme. By treating up to 2000 atoms at a consistent quantum mechanical level of theory, we obtain an unbiased, almost parameter-free description of the transition state geometry and energetics. The activation energy barrier is calculated to be lowered by 10.5 kcal mol(-1) in the enzyme, compared with the equivalent reaction in water, which is in good agreement with experiment. Natural bond orbital analysis identifies a number of active site residues that are important for transition state stabilization in chorismate mutase. This benchmark study demonstrates that linear-scaling density functional theory techniques are capable of simulating entire enzymes at the ab initio quantum mechanical level of accuracy.
An alternative derivation of ring-polymer molecular dynamics transition-state theory
Hele, Timothy J H
2016-01-01
In a previous article [J. Chem. Phys. 138, 084108 (2013)], we showed that the transition-state-theory ($t\\rightarrow 0_+$) limit of ring-polymer molecular dynamics rate-theory (RPMD-TST) is also the $t\\rightarrow 0_+$ limit of a new type of quantum flux-side time-correlation function, in which the dividing surfaces are invariant to imaginary-time translation; in other words, that RPMD-TST is a $t\\rightarrow 0_+$ quantum transition-state theory (QTST). Recently, Jang and Voth [J. Chem. Phys. 144, 084110 (2016)] rederived this quantum $t\\rightarrow 0_+$ limit, and claimed that it gives instead the centroid-density approximation. Here we show that the $t\\rightarrow 0_+$ limit derived by Jang and Voth is in fact RPMD-TST.
Band structure and optical transitions in LaFeO3: theory and experiment.
Scafetta, Mark D; Cordi, Adam M; Rondinelli, James M; May, Steven J
2014-12-17
The optical absorption properties of LaFeO(3) (LFO) have been calculated using density functional theory and experimentally measured from several high quality epitaxial films using variable angle spectroscopic ellipsometry. We have analyzed the calculated absorption spectrum using different Tauc models and find the model based on a direct-forbidden transition gives the best agreement with the ab initio band gap energies and band dispersions. We have applied this model to the experimental data and determine the band gap of epitaxial LFO to be ∼2.34 eV, with a slight dependence on strain state. This approach has also been used to analyze the higher indirect transition at ∼3.4 eV. Temperature dependent ellipsometry measurements further confirm our theoretical analysis of the nature of the transitions. This works helps to provide a general approach for accurate determination of band gaps and transition energies in complex oxide materials.
Demographic changes and nationalism.
Vishnevskii, A G
1995-01-01
This article examines the different characteristics of the many peoples inhabiting what used to be the Soviet Union and communist Eastern Europe, including Yugoslavia. The differences among these nationalities, or ethnic groups, are illustrated using the example of demographic modernization, showing how different peoples have or have not passed through the demographic transition process. The author looks at ethnic differences in mortality, fertility, natural increase, and migration, as well as economic and social inequalities among ethnic groups. The prospects for inter-ethnic conflict are assessed.
Zheng, Jingjing; Truhlar, Donald G
2012-01-01
Complex molecules often have many structures (conformations) of the reactants and the transition states, and these structures may be connected by coupled-mode torsions and pseudorotations; some but not all structures may have hydrogen bonds in the transition state or reagents. A quantitative theory of the reaction rates of complex molecules must take account of these structures, their coupled-mode nature, their qualitatively different character, and the possibility of merging reaction paths at high temperature. We have recently developed a coupled-mode theory called multi-structural variational transition state theory (MS-VTST) and an extension, called multi-path variational transition state theory (MP-VTST), that includes a treatment of the differences in the multi-dimensional tunneling paths and their contributions to the reaction rate. The MP-VTST method was presented for unimolecular reactions in the original paper and has now been extended to bimolecular reactions. The MS-VTST and MP-VTST formulations of variational transition state theory include multi-faceted configuration-space dividing surfaces to define the variational transition state. They occupy an intermediate position between single-conformation variational transition state theory (VTST), which has been used successfully for small molecules, and ensemble-averaged variational transition state theory (EA-VTST), which has been used successfully for enzyme kinetics. The theories are illustrated and compared here by application to three thermal rate constants for reactions of ethanol with hydroxyl radical--reactions with 4, 6, and 14 saddle points.
Random Matrix Theory with U(N) Racah Algebra for Transition Strengths
Kota, V K B
2015-01-01
For finite quantum many-particle systems, a given system, induced by a transition operator, makes transitions from its states to the states of the same system or to those of another system. Examples are electromagnetic transitions (then the initial and final systems are same), nuclear beta and double beta decay (then the initial and final systems are different), particle addition to or removal from a given system and so on. Working towards developing a complete statistical theory for transition strength densities (transition strengths multiplied by the density of states at the initial and final energies), we have started a program to derive formulas for the lower order bivariate moments of the strength densities generated by a variety of transition operators. In this paper results are presented for a transition operator that removes $k_0$ number of particle by considering $m$ spinless fermions in $N$ single particle states. The Hamiltonian that is $k$-body is represented by EGUE($k$) [embedded Gaussian unitar...
Bystrov, Evgenia
2014-01-01
Artikkel keskendub küsimusele, millised on seosed väärtusorientatsiooni ja perekonna käitumise vahel, aluseks maailma väärtusuuringu andmeid aastatest 1981-2008 ning lisaks veel 45 riigi andmed abielude kohta. Esindatud on ka Eesti
Bystrov, Evgenia
2014-01-01
Artikkel keskendub küsimusele, millised on seosed väärtusorientatsiooni ja perekonna käitumise vahel, aluseks maailma väärtusuuringu andmeid aastatest 1981-2008 ning lisaks veel 45 riigi andmed abielude kohta. Esindatud on ka Eesti
Theory of the vortex-clustering transition in a confined two-dimensional quantum fluid
Yu, Xiaoquan; Billam, Thomas P.; Nian, Jun; Reeves, Matthew T.; Bradley, Ashton S.
2016-08-01
Clustering of like-sign vortices in a planar bounded domain is known to occur at negative temperature, a phenomenon that Onsager demonstrated to be a consequence of bounded phase space. In a confined superfluid, quantized vortices can support such an ordered phase, provided they evolve as an almost isolated subsystem containing sufficient energy. A detailed theoretical understanding of the statistical mechanics of such states thus requires a microcanonical approach. Here we develop an analytical theory of the vortex clustering transition in a neutral system of quantum vortices confined to a two-dimensional disk geometry, within the microcanonical ensemble. The choice of ensemble is essential for identifying the correct thermodynamic limit of the system, enabling a rigorous description of clustering in the language of critical phenomena. As the system energy increases above a critical value, the system develops global order via the emergence of a macroscopic dipole structure from the homogeneous phase of vortices, spontaneously breaking the Z2 symmetry associated with invariance under vortex circulation exchange, and the rotational SO (2 ) symmetry due to the disk geometry. The dipole structure emerges characterized by the continuous growth of the macroscopic dipole moment which serves as a global order parameter, resembling a continuous phase transition. The critical temperature of the transition, and the critical exponent associated with the dipole moment, are obtained exactly within mean-field theory. The clustering transition is shown to be distinct from the final state reached at high energy, known as supercondensation. The dipole moment develops via two macroscopic vortex clusters and the cluster locations are found analytically, both near the clustering transition and in the supercondensation limit. The microcanonical theory shows excellent agreement with Monte Carlo simulations, and signatures of the transition are apparent even for a modest system of 100
The omega --> pi0 gamma* and phi --> pi0 gamma* transition form factors in dispersion theory
Schneider, Sebastian P; Niecknig, Franz
2012-01-01
We calculate the omega --> pi0 gamma* and phi --> pi0 gamma* electromagnetic transition form factors based on dispersion theory, relying solely on a previous dispersive analysis of the corresponding three-pion decays and the pion vector form factor. We compare our findings to recent measurements of the omega --> pi0 mu+ mu- decay spectrum by the NA60 collaboration, and strongly encourage experimental investigation of the Okubo-Zweig-Iizuka-forbidden phi --> pi0 l+ l- decays in order to understand the strong deviations from vector-meson dominance found in these transition form factors.
Linear and nonlinear theory of the proton beam transit-time oscillator (TTO)
Walsh, John E.; Mostrom, Michael A.; Clark, Randy M.; Arman, M. Joseph; Campbell, Mark M.
1989-07-01
A theoretical characterization is presented for both the small- and large-amplitude behaviors of the intense beam-driven transit-time oscillator device which encompasses the effects of the beam self-fields and space-charge effects. The theory has been employed in the development of expressions for comparison with particle simulation results. Attention is given to the effect of beam-plasma frequency on gain, saturation growth in the monotron, the effects of space-charge depression on the transit angle, and the dependence of monotron performance on beam energy.
Wong-McSweeney, Daniel; Woodcock, James; Waddington, David; Peris, Eulalia; Koziel, Zbigniew; Moorhouse, Andy; Redel-Macías, María Dolores
2016-12-14
The aim of this paper is to determine what non-exposure factors influence the relationship between vibration and noise exposure from the construction of a Light Rapid Transit (LRT) system and the annoyance of nearby residents. Noise and vibration from construction sites are known to annoy residents, with annoyance increasing as a function of the magnitude of the vibration and noise. There is not a strong correlation between exposure and levels of annoyance suggesting that factors not directly related to the exposure may have an influence. A range of attitudinal, situational and demographic factors are investigated with the aim of understanding the wide variation in annoyance for a given vibration exposure. A face-to-face survey of residents (n = 350) near three sites of LRT construction was conducted, and responses were compared to semi-empirical estimates of the internal vibration within the buildings. It was found that annoyance responses due to vibration were strongly influenced by two attitudinal variables, concern about property damage and sensitivity to vibration. Age, ownership of the property and the visibility of the construction site were also important factors. Gender, time at home and expectation of future levels of vibration had much less influence. Due to the measurement methods used, it was not possible to separate out the effects of noise and vibration on annoyance; as such, this paper focusses on annoyance due to vibration exposure. This work concludes that for the most cost-effective reduction of the impact of construction vibration and noise on the annoyance felt by a community, policies should consider attitudinal factors.
Critical test of the mode-coupling theory of the glass transition.
Berthier, Ludovic; Tarjus, Gilles
2010-09-01
In its common implementation, the mode-coupling theory of the glass transition predicts the time evolution of the intermediate scattering functions in viscous liquids on the sole basis of the structural information encoded in two-point density correlations. We provide a critical test of this property and show that the theory fails to describe the strong differences of dynamical behavior seen in two model liquids characterized by very similar pair-correlation functions. Because we use "exact" static information provided by numerical simulations, our results are a direct indication that some important information about the dynamics of viscous liquids is not captured by pair correlations and is thus not described by the mode-coupling theory, even in the temperature regime where the theory is usually applied.
Zhang, Yanchuan; Stecher, Thomas; Cvitaš, Marko T; Althorpe, Stuart C
2014-11-20
Quantum transition-state theory (QTST) and free-energy instanton theory (FEIT) are two closely related methods for estimating the quantum rate coefficient from the free-energy at the reaction barrier. In calculations on one-dimensional models, FEIT typically gives closer agreement than QTST with the exact quantum results at all temperatures below the crossover to deep tunneling, suggesting that FEIT is a better approximation than QTST in this regime. Here we show that this simple trend does not hold for systems of greater dimensionality. We report tests on several collinear and three-dimensional reactions, in which QTST outperforms FEIT over a range of temperatures below crossover, which can extend down to half the crossover temperature (below which FEIT outperforms QTST). This suggests that QTST-based methods such as ring-polymer molecular dynamics (RPMD) may often give closer agreement with the exact quantum results than FEIT.
Tribbia, John Luke
. The STIRPAT method is used to test four social theories of environmental degradation -- the treadmill of production, ecological modernization, urban ecological transitions, and human ecology theories -- by quantifying variables associated with energy use and CO2 emissions drawn from each theory. The specific findings demonstrate that various demographic, economic, and governmental factors are related strongly to metropolitan area energy consumption and county-level CO2 emissions. The human ecology, treadmill of production, and urban ecological transitions theories are important to explaining how and why climate-related impacts differ for a wide variety of local areas in the United States. Related to human ecology and treadmill of production theory, environmental degradation is highest in metropolitan areas and counties with large populations and large economies that have various mechanisms in place to facilitate economic growth. By contrast, some U.S. counties are beginning to remedy their impact on the environment by applying economic and governmental resources toward the mitigation of CO2 emissions, which provides evidence of support for urban ecological transitions theory. However, because climate change is a complex cross-scale global environmental problem and the results in this dissertation confirm that this problem is locally driven by similar population and economic factors also affecting the climate at larger spatial scales, mitigation efforts to reduce energy use and emissions at the local level will be fruitless without a well-coordinated, cross-scale (local to global) ideological shift that puts less priority on economic goals and more on environmental sustainability. These results, and the methodological and theoretical framework applied in this dissertation, thus provide a useful platform for the successful application of future research that specifically addresses mitigation strategies to reduce local-level environmental impacts. This dissertation
Theory of quantum metal to superconductor transitions in highly conducting systems
Energy Technology Data Exchange (ETDEWEB)
Spivak, B.
2010-04-06
We derive the theory of the quantum (zero temperature) superconductor to metal transition in disordered materials when the resistance of the normal metal near criticality is small compared to the quantum of resistivity. This can occur most readily in situations in which 'Anderson's theorem' does not apply. We explicitly study the transition in superconductor-metal composites, in an swave superconducting film in the presence of a magnetic field, and in a low temperature disordered d-wave superconductor. Near the point of the transition, the distribution of the superconducting order parameter is highly inhomogeneous. To describe this situation we employ a procedure which is similar to that introduced by Mott for description of the temperature dependence of the variable range hopping conduction. As the system approaches the point of the transition from the metal to the superconductor, the conductivity of the system diverges, and the Wiedemann-Franz law is violated. In the case of d-wave (or other exotic) superconductors we predict the existence of (at least) two sequential transitions as a function of increasing disorder: a d-wave to s-wave, and then an s-wave to metal transition.
Hedgehogs in Wilson loops and phase transition in SU(2) Yang-Mills theory
Belavin, V A; Kozlov, I E
2006-01-01
We suggest that the gauge-invariant hedgehogs-like structures in the Wilson loops are physically interesting degrees of freedom in the Yang-Mills theory. The trajectories of these hedgehogs are closed curves which correspond to center-valued (untraced) Wilson loops and are characterized by the center charge and by the winding number. We show numerically in SU(2) Yang-Mills theory that the density of the hedgehogs in the thermal Wilson-Polyakov line is very sensitive to the finite temperature phase transition. The (additively normalized) hedgehog density behaves as an order parameter: the density is almost independent of the temperature in the confinement phase and changes substantially as the system gets into the deconfinement phase. Our results suggest in particular that the (static) hedgehogs may be relevant degrees of freedom around the deconfinement transition, and thus affect evolution of the quark-gluon plasma in high-energy heavy ion collisions.
Hedgehogs in Wilson loops and phase transition in SU(2) Yang-Mills theory
Energy Technology Data Exchange (ETDEWEB)
Belavin, V.A. [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, RU-117259 Moscow (Russian Federation); Chernodub, M.N. [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, RU-117259 Moscow (Russian Federation) and Department of Theoretical Physics, Uppsala University, P.O. Box 803, S-75108 Uppsala (Sweden)]. E-mail: maxim.chernodub@itep.ru; Kozlov, I.E. [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya 25, RU-117259 Moscow (Russian Federation); Faculty of Physics, Moscow State University, RU-119992 Moscow (Russian Federation)
2006-08-07
We suggest that the gauge-invariant hedgehog-like structures in the Wilson loops are physically interesting degrees of freedom in the Yang-Mills theory. The trajectories of these 'hedgehog loops' are closed curves corresponding to center-valued (untraced) Wilson loops and are characterized by the center charge and winding number. We show numerically in the SU(2) Yang-Mills theory that the density of hedgehog structures in the thermal Wilson-Polyakov line is very sensitive to the finite-temperature phase transition. The (additively normalized) hedgehog line density behaves like an order parameter: The density is almost independent of the temperature in the confinement phase and changes substantially as the system enters the deconfinement phase. In particular, our results suggest that the (static) hedgehog lines may be relevant degrees of freedom around the deconfinement transition and thus affect evolution of the quark-gluon plasma in high-energy heavy-ion collisions.
Nucleon-to-Delta axial transition form factors in relativistic baryon chiral perturbation theory
Geng, L S; Alvarez-Ruso, L; Vacas, M J Vicente
2008-01-01
We report a theoretical study of the axial Nucleon to Delta(1232) ($N\\to\\Delta$) transition form factors up to one-loop order in relativistic baryon chiral perturbation theory. We adopt a formalism in which the $\\Delta$ couplings obey the spin-3/2 gauge symmetry and, therefore, decouple the unphysical spin-1/2 fields. We compare the results with phenomenological form factors obtained from neutrino bubble chamber data and in quark models.
Gaddy, E. M.; Reiss, H. R.
1976-01-01
The 'mean frequency' technique, a simple procedure introduced by Bebb and Gold for the approximate evaluation of sums occurring in high-order perturbation theory, represents a useful approximation method. Its predictions compare favorably to exact results obtained by Gontier and Trahin for multiphoton bound-bound transitions in hydrogen. However, the technique can be in error if the 'mean frequency' lies near certain integers.
Steam Reforming on Transition-metal Carbides from Density-functional Theory
Energy Technology Data Exchange (ETDEWEB)
Vojvodic, Aleksandra
2012-05-11
A screening study of the steam reforming reaction on clean and oxygen covered early transition-metal carbides surfaces is performed by means of density-functional theory calculations. It is found that carbides provide a wide spectrum of reactivities, from too reactive via suitable to too inert. Several molybdenum-based systems are identified as possible steam reforming catalysts. The findings suggest that carbides provide a playground for reactivity tuning, comparable to the one for pure metals.
Phase transitions in strongly coupled 3d Z(N) lattice gauge theories at finite temperature
Borisenko, O; Cortese, G; Fiore, R; Gravina, M; Papa, A; Surzhikov, I
2012-01-01
We perform an analytical and numerical study of the phase transitions in three-dimensional Z(N) lattice gauge theories at finite temperature for N>4. In the strong coupling limit these models are equivalent to a generalized version of the vector Potts models in two dimensions, where Polyakov loops play the role of Z(N) spins. The effective couplings of these two-dimensional spin models are calculated explicitly. It is argued that the effective spin models have two phase transitions of BKT type. This is confirmed by large-scale Monte Carlo simulations. Using a cluster algorithm we locate the position of the critical points and study the critical behavior across both phase transitions in details. In particular, we determine various critical indices, compute the helicity modulus, the average action and the specific heat. A scaling formula for the critical points with N is proposed.
Coordinated encoding between cell types in the retina: insights from the theory of phase transitions
Sharpee, Tatyana
2015-03-01
In this talk I will describe how the emergence of some types of neurons in the brain can be quantitatively described by the theory of transitions between different phases of matter. The two key parameters that control the separation of neurons into subclasses are the mean and standard deviation of noise levels among neurons in the population. The mean noise level plays the role of temperature in the classic theory of phase transitions, whereas the standard deviation is equivalent to pressure, in the case of liquid-gas transitions, or to magnetic field for magnetic transitions. Our results account for properties of two recently discovered types of salamander OFF retinal ganglion cells, as well as the absence of multiple types of ON cells. We further show that, across visual stimulus contrasts, retinal circuits continued to operate near the critical point whose quantitative characteristics matched those expected near a liquid-gas critical point and described by the nearest-neighbor Ising model in three dimensions. Because the retina needs to operate under changing stimulus conditions, the observed parameters of cell types corresponded to metastable states in the region between the spinodal line and the line describing maximally informative solutions. Such properties of neural circuits can maximize information transmission in a given environment while retaining the ability to quickly adapt to a new environment. NSF CAREER award 1254123 and NIH R01EY019493
Theory of the Many-Body Localization Transition in One-Dimensional Systems
Directory of Open Access Journals (Sweden)
Ronen Vosk
2015-09-01
Full Text Available We formulate a theory of the many-body localization transition based on a novel real-space renormalization group (RG approach. The results of this theory are corroborated and intuitively explained with a phenomenological effective description of the critical point and of the “badly conducting” state found near the critical point on the delocalized side. The theory leads to the following sharp predictions: (i The delocalized state established near the transition is a Griffiths phase, which exhibits subdiffusive transport of conserved quantities and sub-ballistic spreading of entanglement. The anomalous diffusion exponent α<1/2 vanishes continuously at the critical point. The system does thermalize in this Griffiths phase. (ii The many-body localization transition is controlled by a new kind of infinite-randomness RG fixed point, where the broadly distributed scaling variable is closely related to the eigenstate entanglement entropy. Dynamically, the entanglement grows as ∼logt at the critical point, as it does in the localized phase. (iii In the vicinity of the critical point, the ratio of the entanglement entropy to the thermal entropy and its variance (and, in fact, all moments are scaling functions of L/ξ, where L is the length of the system and ξ is the correlation length, which has a power-law divergence at the critical point.
Renormalization-group theory for cooling first-order phase transitions in Potts models.
Liang, Ning; Zhong, Fan
2017-03-01
We develop a dynamic field-theoretic renormalization-group (RG) theory for cooling first-order phase transitions in the Potts model. It is suggested that the well-known imaginary fixed points of the q-state Potts model for q>10/3 in the RG theory are the origin of the dynamic scaling found recently from numerical simulations, apart from logarithmic corrections. This indicates that the real and imaginary fixed points of the Potts model are both physical and control the scalings of the continuous and discontinuous phase transitions, respectively, of the model. Our one-loop results for the scaling exponents are already not far away from the numerical results. Further, the scaling exponents depend on q only slightly, consistent with the numerical results. Therefore, the theory is believed to provide a natural explanation of the dynamic scaling including the scaling exponents and their scaling laws for various observables in the cooling first-order phase transition of the Potts model.
Renormalization-group theory for cooling first-order phase transitions in Potts models
Liang, Ning; Zhong, Fan
2017-03-01
We develop a dynamic field-theoretic renormalization-group (RG) theory for cooling first-order phase transitions in the Potts model. It is suggested that the well-known imaginary fixed points of the q -state Potts model for q >10 /3 in the RG theory are the origin of the dynamic scaling found recently from numerical simulations, apart from logarithmic corrections. This indicates that the real and imaginary fixed points of the Potts model are both physical and control the scalings of the continuous and discontinuous phase transitions, respectively, of the model. Our one-loop results for the scaling exponents are already not far away from the numerical results. Further, the scaling exponents depend on q only slightly, consistent with the numerical results. Therefore, the theory is believed to provide a natural explanation of the dynamic scaling including the scaling exponents and their scaling laws for various observables in the cooling first-order phase transition of the Potts model.
Carlson, Rebecca K; Li Manni, Giovanni; Sonnenberger, Andrew L; Truhlar, Donald G; Gagliardi, Laura
2015-01-13
Kohn-Sham density functional theory, resting on the representation of the electronic density and kinetic energy by a single Slater determinant, has revolutionized chemistry, but for open-shell systems, the Kohn-Sham Slater determinant has the wrong symmetry properties as compared to an accurate wave function. We have recently proposed a theory, called multiconfiguration pair-density functional theory (MC-PDFT), in which the electronic kinetic energy and classical Coulomb energy are calculated from a multiconfiguration wave function with the correct symmetry properties, and the rest of the energy is calculated from a density functional, called the on-top density functional, that depends on the density and the on-top pair density calculated from this wave function. We also proposed a simple way to approximate the on-top density functional by translation of Kohn-Sham exchange-correlation functionals. The method is much less expensive than other post-SCF methods for calculating the dynamical correlation energy starting with a multiconfiguration self-consistent-field wave function as the reference wave function, and initial tests of the theory were quite encouraging. Here, we provide a broader test of the theory by applying it to bond energies of main-group molecules and transition metal complexes, barrier heights and reaction energies for diverse chemical reactions, proton affinities, and the water dimerization energy. Averaged over 56 data points, the mean unsigned error is 3.2 kcal/mol for MC-PDFT, as compared to 6.9 kcal/mol for Kohn-Sham theory with a comparable density functional. MC-PDFT is more accurate on average than complete active space second-order perturbation theory (CASPT2) for main-group small-molecule bond energies, alkyl bond dissociation energies, transition-metal-ligand bond energies, proton affinities, and the water dimerization energy.
Transition modes in Ising networks: an approximate theory for macromolecular recognition.
Keating, S; Di Cera, E
1993-07-01
For a statistical lattice, or Ising network, composed of N identical units existing in two possible states, 0 and 1, and interacting according to a given geometry, a set of values can be found for the mean free energy of the 0-->1 transition of a single unit. Each value defines a transition mode in an ensemble of nu N = 3N - 2N possible values and reflects the role played by intermediate states in shaping the energetics of the system as a whole. The distribution of transition modes has a number of intriguing properties. Some of them apply quite generally to any Ising network, regardless of its dimension, while others are specific for each interaction geometry and dimensional embedding and bear on fundamental aspects of analytical number theory. The landscape of transition modes encapsulates all of the important thermodynamic properties of the network. The free energy terms defining the partition function of the system can be derived from the modes by simple transformations. Classical mean-field expressions can be obtained from consideration of the properties of transition modes in a rather straightforward way. The results obtained in the analysis of the transition mode distributions have been used to develop an approximate treatment of the problem of macromolecular recognition. This phenomenon is modeled as a cooperative process that involves a number of recognition subsites across an interface generated by the binding of two macromolecular components. The distribution of allowed binding free energies for the system is shown to be a superposition of Gaussian terms with mean and variance determined a priori by the theory. Application to the analysis of the biologically interaction of thrombin with hirudin has provided some useful information on basic aspects of the interaction, such as the number of recognition subsites involved and the energy balance for binding and cooperative coupling among them. Our results agree quite well with information derived independently
Urcuioli, Peter J; Swisher, Melissa J
2015-03-01
Stimulus class formation is inferred when conditional discrimination training yields new (emergent) conditional relations between the training stimuli. The present experiments demonstrated two such relations in pigeons after successive matching-to-sample training. Experiment 1 showed that transitivity (AC matching) emerged after training on AB and BC arbitrary matching plus BB identity matching: pigeons responded relatively more to the comparisons on AC test trials in which both the A samples and C comparisons were elements of reinforced arbitrary baseline relations involving the same nominal B stimulus. Experiment 2 showed the opposite effect ("anti-transitivity") after training on the same arbitrary relations but with BB oddity instead: pigeons responded relatively more to the comparisons on AC test trials in which the A sample was an element of a reinforced baseline relation and the C comparison was an element of a non-reinforced baseline relation, or vice versa. Experiment 2 also showed that AB and BC training alone generally does not yield an emergent effect. These findings extend the range of emergent phenomena observed in non-human animals and are consistent with predictions from Urcuioli's (2008) theory of pigeons' stimulus class formation. This article is part of a Special Issue entitled: Tribute to Tom Zentall. Copyright © 2014 Elsevier B.V. All rights reserved.
Quantum Phase Transitions and New Scales in QCD-Like Theories
Energy Technology Data Exchange (ETDEWEB)
Unsal, Mithat
2008-07-03
It is commonly believed that in confining vector-like gauge theories the center and chiral symmetry realizations are parametrically entangled, and if phase transitions occur, they must take place around the strong scale {Lambda}{sup -1} of the gauge theory. We demonstrate that (non-thermal) vector-like theories formulated on R{sup 3} x S{sup 1} where S{sup 1} is a spatial circle exhibit new dynamical scales and new phenomena. There are chiral phase transitions taking place at {Lambda}{sup -1}/N{sub c} in the absence of any change in center symmetry. {Lambda}{sup -1}/N{sub c}, invisible in (planar) perturbation theory, is also the scale where abelian versus non-abelian confinement regimes meet. Large N{sub c} volume independence (a working Eguchi-Kawai reduction) provides new insights and independently confirms the existence of these scales. We show that certain phases and scales are outside the reach of holographic (supergravity) modeling of QCD.
Bao, Junwei Lucas; Zheng, Jingjing; Truhlar, Donald G
2016-03-02
Pressure-dependent reactions are ubiquitous in combustion and atmospheric chemistry. We employ a new calibration procedure for quantum Rice-Ramsperger-Kassel (QRRK) unimolecular rate theory within a chemical activation mechanism to calculate the pressure-falloff effect of a radical association with an aromatic ring. The new theoretical framework is applied to the reaction of H with toluene, which is a prototypical reaction in the combustion chemistry of aromatic hydrocarbons present in most fuels. Both the hydrogen abstraction reactions and the hydrogen addition reactions are calculated. Our system-specific (SS) QRRK approach is adjusted with SS parameters to agree with multistructural canonical variational transition state theory with multidimensional tunneling (MS-CVT/SCT) at the high-pressure limit. The new method avoids the need for the usual empirical estimations of the QRRK parameters, and it eliminates the need for variational transition state theory calculations as a function of energy, although in this first application we do validate the falloff curves by comparing SS-QRRK results without tunneling to multistructural microcanonical variational transition state theory (MS-μVT) rate constants without tunneling. At low temperatures, the two approaches agree well with each other, but at high temperatures, SS-QRRK tends to overestimate falloff slightly. We also show that the variational effect is important in computing the energy-resolved rate constants. Multiple-structure anharmonicity, torsional-potential anharmonicity, and high-frequency-mode vibrational anharmonicity are all included in the rate computations, and torsional anharmonicity effects on the density of states are investigated. Branching fractions, which are both temperature- and pressure-dependent (and for which only limited data is available from experiment), are predicted as a function of pressure.
Buchhold, Michael; Everest, Benjamin; Marcuzzi, Matteo; Lesanovsky, Igor; Diehl, Sebastian
2017-01-01
Phase transitions to absorbing states are among the simplest examples of critical phenomena out of equilibrium. The characteristic feature of these models is the presence of a fluctuationless configuration which the dynamics cannot leave, which has proved a rather stringent requirement in experiments. Recently, a proposal to seek such transitions in highly tunable systems of cold-atomic gases offers to probe this physics and, at the same time, to investigate the robustness of these transitions to quantum coherent effects. Here, we specifically focus on the interplay between classical and quantum fluctuations in a simple driven open quantum model which, in the classical limit, reproduces a contact process, which is known to undergo a continuous transition in the "directed percolation" universality class. We derive an effective long-wavelength field theory for the present class of open spin systems and show that, due to quantum fluctuations, the nature of the transition changes from second to first order, passing through a bicritical point which appears to belong instead to the "tricritical directed percolation" class.
Retarded correlators in kinetic theory: branch cuts, poles and hydrodynamic onset transitions
Energy Technology Data Exchange (ETDEWEB)
Romatschke, Paul [University of Colorado, Department of Physics, Boulder, CO (United States); University of Colorado, Center for Theory of Quantum Matter, Boulder, CO (United States)
2016-06-15
In this work the collective modes of an effective kinetic theory description based on the Boltzmann equation in a relaxation-time approximation applicable to gauge theories at weak but finite coupling and low frequencies are studied. Real time retarded two-point correlators of the energy-momentum tensor and the R-charge current are calculated at finite temperature in flat space-times for large N gauge theories. It is found that the real-time correlators possess logarithmic branch cuts which in the limit of large coupling disappear and give rise to non-hydrodynamic poles that are reminiscent of quasi-normal modes in black holes. In addition to branch cuts, correlators can have simple hydrodynamic poles, generalizing the concept of hydrodynamic modes to intermediate wavelength. Surprisingly, the hydrodynamic poles cease to exist for some critical value of the wavelength and coupling reminiscent of the properties of onset transitions. (orig.)
Three dimensional finite temperature SU(3) gauge theory near the phase transition
Bialas, Piotr; Morel, Andre; Petersson, Bengt
2012-01-01
We have measured the correlation function of Polyakov loops on the lattice in three dimensional SU(3) gauge theory near its finite temperature phase transition. Using a new and powerful application of finite size scaling, we furthermore extend the measurements of the critical couplings to considerably larger values of the lattice sizes, both in the temperature and space directions, than was investigated earlier in this theory. With the help of these measurements we perform a detailed finite size scaling analysis, showing that for the critical exponents of the two dimensional three state Potts model the mass and the susceptibility fall on unique scaling curves. This strongly supports the expectation that the gauge theory is in the same universality class. The Nambu-Goto string model on the other hand predicts that the exponent \
Superfluid density in He II near the lambda transition: First principles theory
Energy Technology Data Exchange (ETDEWEB)
Jackson, H.W., E-mail: hwjackson2@gmail.com
2015-03-15
A first principles theory of the λ transition in liquid {sup 4}He was introduced in a recent paper [H. W. Jackson, J. Low Temp. Phys. 155, 1 (2009)]. In that theory critical fluctuations consisting of isothermal fourth sound waves are treated with quantum statistical mechanics methods in deriving formulas for constant volume conditions for specific heat, correlation length, equal time pair correlation function, and isothermal compressibility. To leading order terms in (T{sub λ}−T) the theory yields exact results α′=0 and ν′=2/3 for critical exponents at constant volume. A follow-up study in the present paper demonstrates by a least squares fit that a logarithmic function accurately describes the specific heat at svp when (T{sub λ}−T) is between 10{sup −9} K and 10{sup −5} K. This logarithmic divergent behavior conflicts with previous analyses of experimental data and predictions of renormalization group theory that constant pressure specific heat is finite at T{sub λ}, but Is thermodynamically consistent with logarithmic asymptotic behavior of specific heat at constant volume predicted in the new theory. The first principles theory is extended in this paper to derive formulas for superfluid density and for a relation between superfluid density and correlation length in He II near T{sub λ}. Numerical results based on these formulas are in good agreement with experimental data produced by second sound measurements.
Mökkönen, Harri; Ala-Nissila, Tapio; Jónsson, Hannes
2016-09-07
The recrossing correction to the transition state theory estimate of a thermal rate can be difficult to calculate when the energy barrier is flat. This problem arises, for example, in polymer escape if the polymer is long enough to stretch between the initial and final state energy wells while the polymer beads undergo diffusive motion back and forth over the barrier. We present an efficient method for evaluating the correction factor by constructing a sequence of hyperplanes starting at the transition state and calculating the probability that the system advances from one hyperplane to another towards the product. This is analogous to what is done in forward flux sampling except that there the hyperplane sequence starts at the initial state. The method is applied to the escape of polymers with up to 64 beads from a potential well. For high temperature, the results are compared with direct Langevin dynamics simulations as well as forward flux sampling and excellent agreement between the three rate estimates is found. The use of a sequence of hyperplanes in the evaluation of the recrossing correction speeds up the calculation by an order of magnitude as compared with the traditional approach. As the temperature is lowered, the direct Langevin dynamics simulations as well as the forward flux simulations become computationally too demanding, while the harmonic transition state theory estimate corrected for recrossings can be calculated without significant increase in the computational effort.
Mökkönen, Harri; Ala-Nissila, Tapio; Jónsson, Hannes
2016-09-01
The recrossing correction to the transition state theory estimate of a thermal rate can be difficult to calculate when the energy barrier is flat. This problem arises, for example, in polymer escape if the polymer is long enough to stretch between the initial and final state energy wells while the polymer beads undergo diffusive motion back and forth over the barrier. We present an efficient method for evaluating the correction factor by constructing a sequence of hyperplanes starting at the transition state and calculating the probability that the system advances from one hyperplane to another towards the product. This is analogous to what is done in forward flux sampling except that there the hyperplane sequence starts at the initial state. The method is applied to the escape of polymers with up to 64 beads from a potential well. For high temperature, the results are compared with direct Langevin dynamics simulations as well as forward flux sampling and excellent agreement between the three rate estimates is found. The use of a sequence of hyperplanes in the evaluation of the recrossing correction speeds up the calculation by an order of magnitude as compared with the traditional approach. As the temperature is lowered, the direct Langevin dynamics simulations as well as the forward flux simulations become computationally too demanding, while the harmonic transition state theory estimate corrected for recrossings can be calculated without significant increase in the computational effort.
Tokuyama, Michio
2017-01-01
The renormalized simplified model is proposed to investigate indirectly how the static structure factor plays an important role in renormalizing a quadratic nonlinear term in the ideal mode-coupling memory function near the glass transition. The renormalized simplified recursion equation is then derived based on the time-convolutionless mode-coupling theory (TMCT) proposed recently by the present author. This phenomenological approach is successfully applied to check from a unified point of view how strong liquids are different from fragile liquids. The simulation results for those two types of liquids are analyzed consistently by the numerical solutions of the recursion equation. Then, the control parameter dependence of the renormalized nonlinear exponent in both types of liquids is fully investigated. Thus, it is shown that there exists a novel difference between the universal behavior in strong liquids and that in fragile liquids not only for their transport coefficients but also for their dynamics.
Deconfinement transition in SU(2) Yang-Mills theory: a two-loop study
Reinosa, U; Tissier, M; Wschebor, N
2014-01-01
In a recent work we have proposed a perturbative approach for the study of the phase transition of pure Yang-Mills theories at finite temperature. This is based on a simple massive extension of background field methods in the Landau-DeWitt gauge, where the gluon mass term is related to the existence of Gribov ambiguities. We have shown that a one-loop calculation of the background field effective potential describes well the phase structure of the SU(2) and SU(3) theories. Here, we present the calculation of the next-to-leading order contribution in perturbation theory for the SU(2) case. In particular, we compute the background field effective potential at two-loop order and the corresponding Polyakov loop, a gauge invariant order parameter of the transition, at one-loop order. We show that the two-loop correction brings the critical temperature closer to its actual value as compared to the previous one-loop result. We also compute the thermodynamic pressure as a function of the temperature and show that two...
Safety performance of traffic phases and phase transitions in three phase traffic theory.
Xu, Chengcheng; Liu, Pan; Wang, Wei; Li, Zhibin
2015-12-01
Crash risk prediction models were developed to link safety to various phases and phase transitions defined by the three phase traffic theory. Results of the Bayesian conditional logit analysis showed that different traffic states differed distinctly with respect to safety performance. The random-parameter logit approach was utilized to account for the heterogeneity caused by unobserved factors. The Bayesian inference approach based on the Markov Chain Monte Carlo (MCMC) method was used for the estimation of the random-parameter logit model. The proposed approach increased the prediction performance of the crash risk models as compared with the conventional logit model. The three phase traffic theory can help us better understand the mechanism of crash occurrences in various traffic states. The contributing factors to crash likelihood can be well explained by the mechanism of phase transitions. We further discovered that the free flow state can be divided into two sub-phases on the basis of safety performance, including a true free flow state in which the interactions between vehicles are minor, and a platooned traffic state in which bunched vehicles travel in successions. The results of this study suggest that a safety perspective can be added to the three phase traffic theory. The results also suggest that the heterogeneity between different traffic states should be considered when estimating the risks of crash occurrences on freeways.
Bassett-Gunter, Rebecca L; Levy-Milne, Ryna; Naylor, Patti Jean; Symons Downs, Danielle; Benoit, Cecilia; Warburton, Darren E.R.; Chris M. Blanchard; Rhodes, Ryan E
2013-01-01
Background Transitioning to parenthood is a major life event that may impact parents’ personal lifestyles, yet there is an absence of theory-based research examining the impact of parenthood on motives for dietary behaviour. As a result, we are unaware of the social cognitive variables that predict eating behaviour among those transitioning to parenthood. The purpose of the study was to examine eating behaviour motives across 12 months within the framework of the theory of planned behavior (T...
Pai, David; Lacoste, Deanna; Laux, Christophe
2009-10-01
In atmospheric pressure air preheated from 300 to 1000 K, the Nanosecond Repetitively Pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and inter-electrode gap distance) of each discharge regime. Notably, there is a minimum gap distance for the existence of the glow regime that increases with decreasing gas temperature. A theory is developed to describe the Corona-to-Glow (C-G) and Glow-to-Spark (G-S) transitions for NRP discharges. The C-G transition is shown to depend on the Avalanche-to-Streamer Transition (AST) as well as the electric field strength in the positive column. The G-S transition is due to the thermal ionization instability. The minimum gap distance for the existence of the glow regime can be understood by considering that the applied voltage of the AST must be lower than that of the thermal ionization instability. This is a previously unknown criterion for generating glow discharges, as it does not correspond to the Paschen minimum or to the Meek-Raether criterion.
The Geography of Solar Photovoltaics (PV and a New Low Carbon Urban Transition Theory
Directory of Open Access Journals (Sweden)
Peter Newton
2013-06-01
Full Text Available This paper examines the early phases of a 21st century energy transition that involves distributed generation technologies employing low or zero carbon emission power sources and their take-up within Australia, with particular reference to the major cities and solar photovoltaics (PV. This transition is occurring in a nation with significant path dependency to overcome in relation to fossil fuel use. Tracking the diffusion of solar PV technology within Australia over the past decade provides a basis for assessing those factors underpinning its exponential growth and its associated geography of diffusion. Positive evidence that there are pathways for cities to decarbonise is apparent but there appear to be different pathways for different city forms with lower density suburban areas showing the biggest take-up of household-based energy technologies. This suggests a model for the low carbon urban transition involving combinations of simple technological changes and harder structural changes, depending upon which parts of the urban fabric are in focus. This is being called a New Low Carbon Urban Transition Theory.
Peake, Sharon; McDowall, Almuth
2012-01-01
In a rapidly changing world of work, little research exists on mid-career transitions. We investigated these using the open-systems approach of chaos theory as a guiding metaphor and conducted interviews with seven mid-career individuals chosen for their experience of a significant mid-career transition. Four common themes were identified through…
Pepperell, Jennifer L.; Rubel, Deborah J.
2009-01-01
This research explored the experiences of gifted girls transitioning from elementary school to sixth and seventh grade. The current literature indicates that gifted girls often struggle emotionally during this transition. Seven research participants were selected and interviewed over a four-month period. Grounded theory methodology was used to…
Toyoizumi, Taro; Miyamoto, Hiroyuki; Yazaki-Sugiyama, Yoko; Atapour, Nafiseh; Hensch, Takao K; Miller, Kenneth D
2013-10-02
What causes critical periods (CPs) to open? For the best-studied case, ocular dominance plasticity in primary visual cortex in response to monocular deprivation (MD), the maturation of inhibition is necessary and sufficient. How does inhibition open the CP? We present a theory: the transition from pre-CP to CP plasticity arises because inhibition preferentially suppresses responses to spontaneous relative to visually driven input activity, switching learning cues from internal to external sources. This differs from previous proposals in (1) arguing that the CP can open without changes in plasticity mechanisms when activity patterns become more sensitive to sensory experience through circuit development, and (2) explaining not simply a transition from no plasticity to plasticity, but a change in outcome of MD-induced plasticity from pre-CP to CP. More broadly, hierarchical organization of sensory-motor pathways may develop through a cascade of CPs induced as circuit maturation progresses from "lower" to "higher" cortical areas.
Structure of chiral phase transitions at finite temperature in abelian gauge theories
Energy Technology Data Exchange (ETDEWEB)
Fukazawa, Kenji [Kure National College of Technology, Kure (Japan); Inagaki, Tomohiro [Information Media Center, Hiroshima Univ., Hiroshima (Japan); Mukaigawa, Seiji [Department of Electrical and Electronic Engineering, Faculty of Engineering, Iwate Univ., Iwate (Japan); Muta, Taizo [Department of Physics, Hiroshima Univ., Hiroshima (Japan)
2001-06-01
The mechanism of chiral symmetry breaking is investigated in strong-coupling Abelian gauge theories at finite temperature. The Schwinger-Dyson equation in the Landau gauge is employed in the real time formalism and is solved numerically within the framework of the instantaneous exchange approximation, including the effect of the thermal mass for the photon propagator. It is found that the chiral symmetry is broken below the critical temperature T for sufficiently large coupling {alpha}. The chiral phase transition is found to be of second order, and the phase diagram in the T-{alpha} plane is obtained. It is investigated how the structure of the chiral phase transition is affected by the thermal mass in the photon propagator. (author)
Structure of chiral phase transitions at finite temperature in Abelian gauge theories
Fukazawa, K; Mukaigawa, S; Muta, T; Fukazawa, Kenji; Inagaki, Tomohiro; Mukaigawa, Seiji; Muta, Taizo
1999-01-01
The mechanism of the chiral symmetry breaking is investigated in the strong-coupling Abelian gauge theories at finite temperature. The Schwinger-Dyson equation in Landau gauge is employed in the real time formalism and is solved numerically within the framework of the instantaneous exchange approximation including the effect of the hard thermal loop for the photon propagator. It is found that the chiral symmetry is broken below the critical temperature T for sufficiently large coupling. The chiral phase transition is found to be of the 2nd order and the phase diagram on the $T-\\alpha$ plane is obtained. It is investigated how the structure of the chiral phase transition is affected by the hard thermal loops in the photon propagator.
de La Sierra, Ruben Ulises
The present study introduces entropy mapping as a comprehensive method to analyze and describe complex interactive systems; and to assess the effect that entropy has in paradigm changes as described by transition theory. Dynamics of interactions among environmental, economic and demographic conditions affect a number of fast growing locations throughout the world. One of the regions especially affected by accelerated growth in terms of demographic and economic development is the border region between Mexico and the US. As the contrast between these countries provides a significant economic and cultural differential, the dynamics of capital, goods, services and people and the rates at which they interact are rather unique. To illustrate the most fundamental economic and political changes affecting the region, a background addressing the causes for these changes leading to the North America Free Trade Agreement (NAFTA) is presented. Although the concept of thermodynamic entropy was first observed in physical sciences, a relevant homology exists in biological, social and economic sciences as the universal tendency towards disorder, dissipation and equilibrium is present in these disciplines when energy or resources become deficient. Furthermore, information theory is expressed as uncertainty and randomness in terms of efficiency in transmission of information. Although entropy in closed systems is unavoidable, its increase in open systems, can be arrested by a flux of energy, resources and/or information. A critical component of all systems is the boundary. If a boundary is impermeable, it will prevent energy flow from the environment into the system; likewise, if the boundary is too porous, it will not be able to prevent the dissipation of energy and resources into the environment, and will not prevent entropy from entering. Therefore, two expressions of entropy--thermodynamic and information--are identified and related to systems in transition and to spatial
Phase transitions in strongly interacting quantum field theories. QED{sub 3} vs. QCD
Energy Technology Data Exchange (ETDEWEB)
Bonnet, J.A.
2013-07-15
In this thesis, we investigate strongly coupled quantum field theories on the examples of (2+1) dimensional Quantumelectrodynamics (QED{sub 3}) and (3+1) dimensional Quantum Chromodynamics (QCD) in the framework of Dyson-Schwinger equations. We firstly focus on the chiral phase transition in QED{sub 3} as a low-energy effective theory for high-temperature superconductors. These materials are inherently anisotropic, as shown by experiments. We therefore focus on the influence of an anisotropic spacetime onto the critical number of fermion flavors for chiral symmetry breaking at zero and finite temperature. The findings are summarized in phase diagrams for the critical number of fermion flavors as a function of the independent anisotropic velocities and temperature. These were the first calculations considering anisotropic QED{sub 3} at finite temperatures. Furthermore, the presented investigations elaborate on the critical scaling behavior close to the merging region of the thermal phase transition line and the quantum phase transition point. The most important results include the finding that anisotropy provides an external parameter that determines the scaling scenario. Secondly, the QCD part of this thesis consists of a feasibility study of the implementation of external magnetic fields into the Dyson-Schwinger formalism. This study serves as a basis for further investigations of e.g. the dynamical mass generation at finite temperatures and densities. This will allow to contribute to the discussions on the phenomenon of (inverse) magnetic catalysis from a functional methods' point of view. Furthermore, we present the first successful extraction of a dressed Wilson loop from Dyson-Schwinger equations. It represents an observable for confinement that was recently introduced in the framework of lattice gauge theory. In addition, its connection with the conventional Wilson loop allows for a direct extraction of the string tension.
Modal Transition Systems as the Basis for Interface Theories and Product Lines
DEFF Research Database (Denmark)
Nyman, Ulrik
paper describes a framework for software product lines which can be instantiated for different design languages. Introducing the concept of color-blindness to describe the inability of an environment to distinguish the difference between several outputs, members of the software product line......This thesis presents research taking its outset in component-based software development, interface theory and software product lines, as well as modeling formalisms for describing component based software systems and their interfaces. The main part of the thesis consists of five papers. The first...... is an explicit separation of assumptions from guarantees and the presentation of a formally derived composition operator. The second of these papers present an interface theory combining Interface Automata and Modal Transition Systems into Modal I/O Automata. A formal correspondence between Interface Automata...
A selection rule for transitions in PT-symmetric quantum theory
Mead, Lawrence R
2016-01-01
Carl Bender and collaborators have developed a quantum theory governed by Hamiltonians that are PT-symmetric rather than Hermitian. To implement this theory, the inner product was redefined to guarantee positive norms of eigenstates of the Hamiltonian. In the general case, which includes arbitrary time-dependence in the Hamiltonian, a modification of the Schrodinger equation is necessary as shown by Gong and Wang to conserve probability. In this paper, we derive the following selection rule: transitions induced by time dependence in a PT-symmetric Hamiltonian cannot occur between normalized states of differing PT-norm. We show three examples of this selection rule in action: two matrix models and one in the continuum.
Interfaces and wetting transition on the half plane. Exact results from field theory
Delfino, Gesualdo; Squarcini, Alessio
2013-05-01
We consider the scaling limit of a generic ferromagnetic system with a continuous phase transition, on the half plane with boundary conditions leading to the equilibrium of two different phases below criticality. We use general properties of low-energy two-dimensional field theory to determine exact asymptotics of the magnetization profile perpendicular to the boundary, to show the presence of an interface with endpoints pinned to the boundary, and to determine its passage probability. The midpoint average distance of the interface from the boundary grows as the square root of the distance between the endpoints, unless the reflection amplitude of the bulk excitations on the boundary possesses a stable bound state pole. The contact angle of the phenomenological wetting theory is exactly related to the location of this pole. Results available from the lattice solution of the Ising model are recovered as a particular case.
Device modeling of superconductor transition edge sensors based on the two-fluid theory
Wang, Tian-Shun; Zhu, Qing-Feng; Wang, Jun-Xian; Li, Tie-Fu; Liu, Jian-She; Chen, Wei; Zhou, Xingxiang
2012-01-01
In order to support the design and study of sophisticated large scale transition edge sensor (TES) circuits, we use basic SPICE elements to develop device models for TESs based on the superfluid-normal fluid theory. In contrast to previous studies, our device model is not limited to small signal simulation, and it relies only on device parameters that have clear physical meaning and can be easily measured. We integrate the device models in design kits based on powerful EDA tools such as CADENCE and OrCAD, and use them for versatile simulations of TES circuits. Comparing our simulation results with published experimental data, we find good agreement which suggests that device models based on the two-fluid theory can be used to predict the behavior of TES circuits reliably and hence they are valuable for assisting the design of sophisticated TES circuits.
Toward Ubiquitous Blood Pressure Monitoring via Pulse Transit Time: Theory and Practice.
Mukkamala, Ramakrishna; Hahn, Jin-Oh; Inan, Omer T; Mestha, Lalit K; Kim, Chang-Sei; Töreyin, Hakan; Kyal, Survi
2015-08-01
Ubiquitous blood pressure (BP) monitoring is needed to improve hypertension detection and control and is becoming feasible due to recent technological advances such as in wearable sensing. Pulse transit time (PTT) represents a well-known potential approach for ubiquitous BP monitoring. The goal of this review is to facilitate the achievement of reliable ubiquitous BP monitoring via PTT. We explain the conventional BP measurement methods and their limitations; present models to summarize the theory of the PTT-BP relationship; outline the approach while pinpointing the key challenges; overview the previous work toward putting the theory to practice; make suggestions for best practice and future research; and discuss realistic expectations for the approach.
Density-functional theory for fluid-solid and solid-solid phase transitions
Bharadwaj, Atul S.; Singh, Yashwant
2017-03-01
We develop a theory to describe solid-solid phase transitions. The density functional formalism of classical statistical mechanics is used to find an exact expression for the difference in the grand thermodynamic potentials of the two coexisting phases. The expression involves both the symmetry conserving and the symmetry broken parts of the direct pair correlation function. The theory is used to calculate phase diagram of systems of soft spheres interacting via inverse power potentials u (r ) =ɛ "close="1 /n )">σ /r n , where parameter n measures softness of the potential. We find that for 1 /n ≥0.154 the body-centred-cubic (bcc) structure is preferred. The bcc structure transforms into the fcc structure upon increasing the density. The calculated phase diagram is in good agreement with the one found from molecular simulations.
Directory of Open Access Journals (Sweden)
Berry Patricia H
2010-04-01
Full Text Available Abstract Background Transitions often occur suddenly and can be traumatic to both patients with advanced disease and their families. The purpose of this study was to explore the transition experience of older rural persons with advanced cancer and their families from the perspective of palliative home care patients, bereaved family caregivers, and health care professionals. The specific aims were to: (1 describe the experience of significant transitions experienced by older rural persons who were receiving palliative home care and their families and (2 develop a substantive theory of transitions in this population. Methods Using a grounded theory approach, 27 open-ended individual audio-taped interviews were conducted with six older rural persons with advanced cancer and 10 bereaved family caregivers. Four focus group interviews were conducted with 12 palliative care health care professionals. All interviews were transcribed verbatim, coded, and analyzed using Charmaz's constructivist grounded theory approach. Results Within a rural context of isolation, lack of information and limited accessibility to services, and values of individuality and community connectedness, older rural palliative patients and their families experienced multiple complex transitions in environment, roles/relationships, activities of daily living, and physical and mental health. Transitions disrupted the lives of palliative patients and their caregivers, resulting in distress and uncertainty. Rural palliative patients and their families adapted to transitions through the processes of "Navigating Unknown Waters". This tentative theory includes processes of coming to terms with their situation, connecting, and redefining normal. Timely communication, provision of information and support networks facilitated the processes. Conclusion The emerging theory provides a foundation for future research. Significant transitions identified in this study may serve as a focus for
Phase Transition in Gauge Theories, Monopoles and the Multiple Point Principle
Das, C. R.; Laperashvili, L. V.
This review is devoted to the Multiple Point Principle (MPP), according to which several vacuum states with the same energy density exist in Nature. The MPP is implemented to the Standard Model (SM), Family replicated gauge group model (FRGGM) and phase transitions in gauge theories with/without monopoles. Using renormalization group equations for the SM, the effective potential in the two-loop approximation is investigated, and the existence of its postulated second minimum at the fundamental scale is confirmed. Phase transitions in the lattice gauge theories are reviewed. The lattice results for critical coupling constants are compared with those of the Higgs monopole model, in which the lattice artifact monopoles are replaced by the point-like Higgs scalar particles with magnetic charge. Considering our (3+1)-dimensional space-time as, in some way, discrete or imagining it as a lattice with a parameter a = λP, where λP is the Planck length, we have investigated the additional contributions of monopoles to the β-functions of renormalization group equations for running fine structure constants αi(μ) (i = 1, 2, 3 correspond to the U(1), SU(2) and SU(3) gauge groups of the SM) in the FRGGM extended beyond the SM at high energies. It is shown that monopoles have Nfam times smaller magnetic charge in the FRGGM than in the SM (Nfam is a number of families in the FRGGM). We have estimated also the enlargement of a number of fermions in the FRGGM leading to the suppression of the asymptotic freedom in the non-Abelian theory. We have reviewed that, in contrast to the case of the Anti-grand-unified-theory (AGUT), there exists a possibility of unification of all gauge interactions (including gravity) near the Planck scale due to monopoles. The possibility of the [SU(5)]3 or [SO(10)]3 unification at the GUT-scale ~1018 GeV is briefly considered.
Powell, Stephen; Chalker, J. T.
2008-10-01
We derive a continuum theory for the phase transition in a classical dimer model on the cubic lattice, observed in recent Monte Carlo simulations. Our derivation relies on the mapping from a three-dimensional classical problem to a two-dimensional quantum problem, by which the dimer model is related to a model of hard-core bosons on the kagome lattice. The dimer-ordering transition becomes a superfluid Mott insulator quantum phase transition at fractional filling, described by an SU(2)-invariant continuum theory.
An introduction to the Ginzburg-Landau theory of phase transitions and nonequilibrium patterns
Hohenberg, P. C.; Krekhov, A. P.
2015-04-01
This paper presents an introduction to phase transitions and critical phenomena on the one hand, and nonequilibrium patterns on the other, using the Ginzburg-Landau theory as a unified language. In the first part, mean-field theory is presented, for both statics and dynamics, and its validity tested self-consistently. As is well known, the mean-field approximation breaks down below four spatial dimensions, where it can be replaced by a scaling phenomenology. The Ginzburg-Landau formalism can then be used to justify the phenomenological theory using the renormalization group, which elucidates the physical and mathematical mechanism for universality. In the second part of the paper it is shown how near pattern forming linear instabilities of dynamical systems, a formally similar Ginzburg-Landau theory can be derived for nonequilibrium macroscopic phenomena. The real and complex Ginzburg-Landau equations thus obtained yield nontrivial solutions of the original dynamical system, valid near the linear instability. Examples of such solutions are plane waves, defects such as dislocations or spirals, and states of temporal or spatiotemporal (extensive) chaos.
An introduction to the Ginzburg–Landau theory of phase transitions and nonequilibrium patterns
Energy Technology Data Exchange (ETDEWEB)
Hohenberg, P.C., E-mail: pierre.hohenberg@nyu.edu [Department of Physics, New York University, New York, NY 10012 (United States); Krekhov, A.P. [Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen (Germany)
2015-04-04
This paper presents an introduction to phase transitions and critical phenomena on the one hand, and nonequilibrium patterns on the other, using the Ginzburg–Landau theory as a unified language. In the first part, mean-field theory is presented, for both statics and dynamics, and its validity tested self-consistently. As is well known, the mean-field approximation breaks down below four spatial dimensions, where it can be replaced by a scaling phenomenology. The Ginzburg–Landau formalism can then be used to justify the phenomenological theory using the renormalization group, which elucidates the physical and mathematical mechanism for universality. In the second part of the paper it is shown how near pattern forming linear instabilities of dynamical systems, a formally similar Ginzburg–Landau theory can be derived for nonequilibrium macroscopic phenomena. The real and complex Ginzburg–Landau equations thus obtained yield nontrivial solutions of the original dynamical system, valid near the linear instability. Examples of such solutions are plane waves, defects such as dislocations or spirals, and states of temporal or spatiotemporal (extensive) chaos.
Phase transitions in number theory: from the birthday problem to Sidon sets.
Luque, Bartolo; Torre, Iván G; Lacasa, Lucas
2013-11-01
In this work, we show how number theoretical problems can be fruitfully approached with the tools of statistical physics. We focus on g-Sidon sets, which describe sequences of integers whose pairwise sums are different, and propose a random decision problem which addresses the probability of a random set of k integers to be g-Sidon. First, we provide numerical evidence showing that there is a crossover between satisfiable and unsatisfiable phases which converts to an abrupt phase transition in a properly defined thermodynamic limit. Initially assuming independence, we then develop a mean-field theory for the g-Sidon decision problem. We further improve the mean-field theory, which is only qualitatively correct, by incorporating deviations from independence, yielding results in good quantitative agreement with the numerics for both finite systems and in the thermodynamic limit. Connections between the generalized birthday problem in probability theory, the number theory of Sidon sets and the properties of q-Potts models in condensed matter physics are briefly discussed.
Hirschi, Andreas
2010-01-01
Chance events are considered important in career development, yet little empirical research is available on their predictors and consequences. The present study investigated socio-demographic (gender, nationality, school-type), personality (openness, locus of control) and career development variables (career decidedness, career planning) in…
Indian Academy of Sciences (India)
Gültekin Çelik; Şule Ateş
2008-09-01
Transition probabilities for some excited s–p and p–s transition arrays of neutral nitrogen have been calculated using the weakest bound electron potential model theory (WBEPMT) for the investigation of effects of expectation values of radii.We have used both numerical non-relativistic Hartree-Fock (NRHF) wave functions and numerical Coulomb approximation (NCA) wave functions to calculate expectation values of radii. The transition probability results obtained using the parameters determined with two different wave functions agree well with each other and accepted values taken from NIST for low values of transition probability. However, the NRHF wave functions present better results for p–s transitions, while NCA wave functions are better in s–p transitions for large values of transition probability.
Hele, Timothy J H; Althorpe, Stuart C
2013-02-28
Surprisingly, there exists a quantum flux-side time-correlation function which has a non-zero t → 0+ limit and thus yields a rigorous quantum generalization of classical transition-state theory (TST). In this Part I of two articles, we introduce the new time-correlation function and derive its t → 0+ limit. The new ingredient is a generalized Kubo transform which allows the flux and side dividing surfaces to be the same function of path-integral space. Choosing this function to be a single point gives a t → 0+ limit which is identical to an expression introduced on heuristic grounds by Wigner in 1932; however, this expression does not give positive-definite quantum statistics, causing it to fail while still in the shallow-tunnelling regime. Positive-definite quantum statistics is obtained only if the dividing surface is invariant to imaginary-time translation, in which case the t → 0+ limit is identical to ring-polymer molecular dynamics (RPMD) TST. The RPMD-TST rate is not a strict upper bound to the exact quantum rate, but is a good approximation to one if real-time coherence effects are small. Part II will show that the RPMD-TST rate is equal to the exact quantum rate in the absence of recrossing.
Bominaar, Emile L.; Achim, Catalina; Peterson, Jim
1998-07-01
Magnetic linear dichroism (MLD) spectroscopy is a relatively new technique which previously has been almost exclusively applied to atoms. These investigations have revealed that the study of MLD, in conjunction with electronic absorption and magnetic circular dichroism (MCD) spectroscopies, provides significant additional information concerning the electronic structure of atoms. More recent measurements have indicated that MLD is also observable from transition ions in inorganic compounds and metalloproteins. While the theory for atomic MLD has been worked out in considerable detail during the last two decades, an MLD theory of practical utility for the analysis of the spectra derived from the majority of paramagnetic molecules is not available. In the present contribution, the MLD of an electric-dipole-allowed transition between twofold-degenerate molecular spin levels is analyzed, assuming nonsaturating conditions. As for atomic systems, it is found that the MLD of a single molecule is dominated by the term G0. However, this term vanishes in the powder average evaluated for a randomly oriented ensemble of molecules, leading to a drastic reduction of the MLD differential absorption for systems with spin S=1/2 compared to that observed for systems with higher ground-state spin. It is found that MLD and MCD spectroscopies on solution samples have complementary spin-state specific sensitivities which suggest that the two methods can be used to selectively probe the individual metal sites in multicenter metalloprotein assemblies.
M Theory Model of a Big Crunch/Big Bang Transition
Turok, N G; Steinhardt, P J; Turok, Neil; Perry, Malcolm; Steinhardt, Paul J.
2004-01-01
We consider a picture in which the transition from a big crunch to a big bang corresponds to the collision of two empty orbifold planes approaching each other at a constant non-relativistic speed in a locally flat background space-time, a situation relevant to recently proposed cosmological models. We show that $p$-brane states which wind around the extra dimension propagate smoothly and unambiguously across the orbifold plane collision. In particular we calculate the quantum mechanical production of winding M2-branes extending from one orbifold to the other. We find that the resulting density is finite and that the resulting gravitational back-reaction is small. These winding states, which include the string theory graviton, can be propagated smoothly across the transition using a perturbative expansion in the membrane tension, an expansion which from the point of view of string theory is an expansion in {\\it inverse} powers of $\\alpha'$. We argue that interactions should be well-behaved because the string c...
Using optimal transport theory to estimate transition probabilities in metapopulation dynamics
Nichols, Jonathan M.; Spendelow, Jeffrey A.; Nichols, James
2017-01-01
This work considers the estimation of transition probabilities associated with populations moving among multiple spatial locations based on numbers of individuals at each location at two points in time. The problem is generally underdetermined as there exists an extremely large number of ways in which individuals can move from one set of locations to another. A unique solution therefore requires a constraint. The theory of optimal transport provides such a constraint in the form of a cost function, to be minimized in expectation over the space of possible transition matrices. We demonstrate the optimal transport approach on marked bird data and compare to the probabilities obtained via maximum likelihood estimation based on marked individuals. It is shown that by choosing the squared Euclidean distance as the cost, the estimated transition probabilities compare favorably to those obtained via maximum likelihood with marked individuals. Other implications of this cost are discussed, including the ability to accurately interpolate the population's spatial distribution at unobserved points in time and the more general relationship between the cost and minimum transport energy.
Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory
Li, Liang-Sheng; Li, Li; Chen, Xiao-Song
2009-02-01
The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation (MF). The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized. The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition. We find a Curie line where the order parameter is pure magnetization and a spinodal where the order parameter is a mixture of particle density and magnetization. Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density. The spinodal meets the Curie line at the critical endpoint with the reduced density ρ* = ρσ3 = 0.224 and the reduced temperature T* = kT/in = 1.87 (σ is the diameter of Heisenberg hard sphere and in is the coupling constant).
Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory
Institute of Scientific and Technical Information of China (English)
LI Liang-Sheng; LI Li; CHEN Xiao-Song
2009-01-01
The phase transition of Heisenberg fluid has been investigated with the density functional theory in mean-field approximation (MF).The matrix of the second derivatives of the grand canonical potential Ω with respect to the particle density fluctuations and the magnetization fluctuations has been investigated and diagonalized.The smallest eigenvalue being 0 signalizes the phase instability and the related eigenvector characterizes this phase transition.We find a Curie line where the order parameter is pure magnetization and a spinodM where the order parameter is a mixture of particle density and magnetization.Along the spinodal, the character of phase instability changes continuously from predominant condensation to predominant ferromagnetic phase transition with the decrease of total density.The spinodal meets the Curie line at the critical endpoint with the reduced density ρ*= ρσ3=0.224 and the reduced temperature T* = kT/ε = 1.87 (σ is the diameter of Heisenberg hard sphere and e is the coupling constant).
Drying and wetting transitions of a Lennard-Jones fluid: Simulations and density functional theory
Evans, Robert; Stewart, Maria C.; Wilding, Nigel B.
2017-07-01
We report a theoretical and simulation study of the drying and wetting phase transitions of a truncated Lennard-Jones fluid at a flat structureless wall. Binding potential calculations predict that the nature of these transitions depends on whether the wall-fluid attraction has a long ranged (LR) power law decay or is instead truncated, rendering it short ranged (SR). Using grand canonical Monte Carlo simulation and classical density functional theory, we examine both cases in detail. We find that for the LR case wetting is first order, while drying is continuous (critical) and occurs exactly at zero attractive wall strength, i.e., in the limit of a hard wall. In the SR case, drying is also critical but the order of the wetting transition depends on the truncation range of the wall-fluid potential. We characterize the approach to critical drying and wetting in terms of the density and local compressibility profiles and via the finite-size scaling properties of the probability distribution of the overall density. For the LR case, where the drying point is known exactly, this analysis allows us to estimate the exponent ν∥, which controls the parallel correlation length, i.e., the extent of vapor bubbles at the wall. Surprisingly, the value we obtain is over twice that predicted by mean field and renormalization group calculations, despite the fact that our three dimensional system is at the upper critical dimension where mean field theory for critical exponents is expected to hold. Possible reasons for this discrepancy are discussed in the light of fresh insights into the nature of near critical finite-size effects.
人口结构转变及其对宏观经济运行影响评述%Demographic Transition and Its Effects on Macro Economy: A Literature Analysis
Institute of Scientific and Technical Information of China (English)
张馨艺; 张琼
2012-01-01
人口结构转变如何影响宏观经济运行既是一个国际性的命题也是一个颇具中国特色的典型问题,国内外学者已就此展开了长时间的多角度探索,但鲜有研究对此进行系统性总结.本文以人口结构转变理论演进为切入点,结合现有分析方法和结论对人口结构转变影响宏观经济运行的传导路径进行了回顾性梳理.结论表明,首先就方法论而言,人口对宏观经济影响的文献已经从早期的总量分析过渡到了如今的结构性分析,并且学者在分析过程中也逐渐从人口如何影响一国或地区的消费、储蓄、投资、进出口贸易以及国际资本流动等中间变量的角度来思考人口对宏观经济影响的具体传导路径；其次,尽管文献结论倾向于认为人口结构转变会对这些中间变量产生影响,但影响的方向与幅度远未达成一致,从而意味着人口结构转变对宏观经济运行的最终影响并无定论;这既与理论分析未成定论相对应,也与学者所采用的数据和方法不同等密切相关.因此,本文认为尽管分析人口对宏观经济影响的研究颇多,但在中国特色国情背景下相关方面的研究仍任重道远.%How demographic transition affects macro economy has always been not only an international proposition, but also a typical topic with Chinese characteristics. Therefore both domestic and foreign scholars have considered the relationship between population and economic development from various aspects for a long time, while few studies have reached an agreement on conclusions so far. This paper starts with a review on theoretical evolution of related literature, and then retrospectively summarizes possible mechanisms of demographic transition on macro economy. It finds that, firstly, in terms of methodology, related researches have changed their focus on aggregate analysis at the very early first stage to recent structural investigations, and further
Institute of Scientific and Technical Information of China (English)
蔡东汉
2011-01-01
In this paper, we set up a model to inquire the affection of the demographic transition and human capital on the economic growth.Combining the function which describes the population change in the period of the demographic transition and the human growth equation with the Solow model, we obtain a two-dimension dynamical system.It is proved that the dynamical system has at least one equilibrium and the solution of the dynamical system is asymptotically stable, so the economy described by the model has stable growth path when the equilibrium is unique.In the end, the numerical simulation is given to present the affections of the demographic transition and human capital on the economic growth.%建立数学模型探讨了人口转变与人力资本对经济增长的影响.将描述人口转变的倒U字型人口增长率函数和人均人力资本引入Solow模型,结合人均人力资本增长方程得到二维的动力系统.证明动力系统至少存在一个非零平衡点且当非零平衡点惟一时,动力系统的解是渐近稳定的,模型描述的经济具有渐近稳定的经济增长路径.通过数值仿真展现人口转变与人力资本对经济增长的影响.
Can quantum transition state theory be defined as an exact t = 0+ limit?
Jang, Seogjoo; Voth, Gregory A
2016-02-28
The definition of the classical transition state theory (TST) as a t → 0+ limit of the flux-side time correlation function relies on the assumption that simultaneous measurement of population and flux is a well defined physical process. However, the noncommutativity of the two measurements in quantum mechanics makes the extension of such a concept to the quantum regime impossible. For this reason, quantum TST (QTST) has been generally accepted as any kind of quantum rate theory reproducing the TST in the classical limit, and there has been a broad consensus that no unique QTST retaining all the properties of TST can be defined. Contrary to this widely held view, Hele and Althorpe (HA) [J. Chem. Phys. 138, 084108 (2013)] recently suggested that a true QTST can be defined as the exact t → 0+ limit of a certain kind of quantum flux-side time correlation function and that it is equivalent to the ring polymer molecular dynamics (RPMD) TST. This work seeks to question and clarify certain assumptions underlying these suggestions and their implications. First, the time correlation function used by HA as a starting expression is not related to the kinetic rate constant by virtue of linear response theory, which is the first important step in relating a t = 0+ limit to a physically measurable rate. Second, a theoretical analysis calls into question a key step in HA's proof which appears not to rely on an exact quantum mechanical identity. The correction of this makes the true t = 0+ limit of HA's QTST different from the RPMD-TST rate expression, but rather equal to the well-known path integral quantum transition state theory rate expression for the case of centroid dividing surface. An alternative quantum rate expression is then formulated starting from the linear response theory and by applying a recently developed formalism of real time dynamics of imaginary time path integrals [S. Jang, A. V. Sinitskiy, and G. A. Voth, J. Chem. Phys. 140, 154103 (2014)]. It is shown
Phase transition in gauge theories, monopoles and the Multiple Point Principle
Das, C R
2005-01-01
This review is devoted to the Multiple Point Principle (MPP), according to which several vacuum states with the same energy density exist in Nature. The MPP is implemented to the Standard Model (SM), Family replicated gauge group model (FRGGM) and phase transitions in gauge theories with/without monopoles. Lattice gauge theories are reviewed. The lattice results for critical coupling constants are compared with those of the Higgs Monopole Model (HMM), in which the lattice artifact monopoles are replaced by the point-like Higgs scalar particles with a magnetic charge. Considering our (3+1)-dimensional space-time as discrete, for example, as a lattice with a parameter a=\\lambda_P, equal to the Planck length, we have investigated the additional contributions of monopoles to beta-functions of renormalization group equations in the FRGGM extended beyond the SM at high (the Planck scale) energies. We have reviewed that, in contrast to the Anti-grand unified theory (AGUT), there exists a possibility of unification o...
Compression induced phase transition of nematic brush: A mean-field theory study
Energy Technology Data Exchange (ETDEWEB)
Tang, Jiuzhou [Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Xinghua, E-mail: zhangxh@bjtu.edu.cn [School of Science, Beijing Jiaotong University, Beijing 100044 (China); Yan, Dadong, E-mail: yandd@bnu.edu.cn [Department of Physics, Beijing Normal University, Beijing 100875 (China)
2015-11-28
Responsive behavior of polymer brush to the external compression is one of the most important characters for its application. For the flexible polymer brush, in the case of low grafting density, which is widely studied by the Gaussian chain model based theory, the compression leads to a uniform deformation of the chain. However, in the case of high grafting density, the brush becomes anisotropic and the nematic phase will be formed. The normal compression tends to destroy the nematic order, which leads to a complex responsive behaviors. Under weak compression, chains in the nematic brush are buckled, and the bending energy and Onsager interaction give rise to the elasticity. Under deep compression, the responsive behaviors of the nematic polymer brush depend on the chain rigidity. For the compressed rigid polymer brush, the chains incline to re-orientate randomly to maximize the orientational entropy and its nematic order is destroyed. For the compressed flexible polymer brush, the chains incline to fold back to keep the nematic order. A buckling-folding transition takes place during the compressing process. For the compressed semiflexible brush, the chains are collectively tilted to a certain direction, which leads to the breaking of the rotational symmetry in the lateral plane. These responsive behaviors of nematic brush relate to the properties of highly frustrated worm-like chain, which is hard to be studied by the traditional self-consistent field theory due to the difficulty to solve the modified diffusion equation. To overcome this difficulty, a single chain in mean-field theory incorporating Monte Carlo simulation and mean-field theory for the worm-like chain model is developed in present work. This method shows high performance for entire region of chain rigidity in the confined condition.
Spencer, Tracy Lynne Wright Lyons
2013-01-01
Federally mandated transition planning has done little to improve the postsecondary outcomes of people with Asperger's syndrome. Current high school transition planning for students with Asperger's attempts to address some of these areas through family involvement, community inclusion, and the active participation of the student in…
Spencer, Tracy Lynne Wright Lyons
2013-01-01
Federally mandated transition planning has done little to improve the postsecondary outcomes of people with Asperger's syndrome. Current high school transition planning for students with Asperger's attempts to address some of these areas through family involvement, community inclusion, and the active participation of the student in…
Demographic Modelling in Weed Biocontrol
Demographic matrix modeling of plant populations can be a powerful tool to identify key life stage transitions that contribute the most to population growth of an invasive plant and hence should be targeted for disruption. Therefore, this approach has the potential to guide the pre-release selection...
Jump Markov models and transition state theory: the quasi-stationary distribution approach.
Di Gesù, Giacomo; Lelièvre, Tony; Le Peutrec, Dorian; Nectoux, Boris
2016-12-22
We are interested in the connection between a metastable continuous state space Markov process (satisfying e.g. the Langevin or overdamped Langevin equation) and a jump Markov process in a discrete state space. More precisely, we use the notion of quasi-stationary distribution within a metastable state for the continuous state space Markov process to parametrize the exit event from the state. This approach is useful to analyze and justify methods which use the jump Markov process underlying a metastable dynamics as a support to efficiently sample the state-to-state dynamics (accelerated dynamics techniques). Moreover, it is possible by this approach to quantify the error on the exit event when the parametrization of the jump Markov model is based on the Eyring-Kramers formula. This therefore provides a mathematical framework to justify the use of transition state theory and the Eyring-Kramers formula to build kinetic Monte Carlo or Markov state models.
Theory of the vortex-clustering transition in a confined two-dimensional quantum fluid
Yu, Xiaoquan; Nian, Jun; Reeves, Matthew T; Bradley, Ashton S
2016-01-01
Clustering of like-sign vortices in a planar bounded domain is known to occur at negative temperature, a phenomenon that Onsager demonstrated to be a consequence of bounded phase space. In a confined superfluid, quantized vortices can support such an ordered phase, provided they evolve as an almost isolated subsystem containing sufficient energy. A detailed theoretical understanding of the statistical mechanics of such states thus requires a microcanonical approach. Here we develop an analytical theory of the vortex clustering transition in a neutral system of quantum vortices confined to a two-dimensional disk geometry, within the microcanonical ensemble. As the system energy increases above a critical value, the system develops global order via the emergence of a macroscopic dipole structure from the homogeneous phase of vortices, spontaneously breaking the Z2 symmetry associated with invariance under vortex circulation exchange, and the rotational SO(2) symmetry due to the disk geometry. The dipole structu...
Theory for transitions between log and stationary phases: universal laws for lag time
Himeoka, Yusuke
2016-01-01
Quantitative characterization of bacterial growth has gathered substantial attention since Monod's pioneering study. Theoretical and experimental work has uncovered several laws for describing the log growth phase, in which the number of cells grows exponentially. However, microorganism growth also exhibits lag, stationary, and death phases under starvation conditions, in which cell growth is highly suppressed, while quantitative laws or theories for such phases are underdeveloped. In fact, models commonly adopted for the log phase that consist of autocatalytic chemical components, including ribosomes, can only show exponential growth or decay in a population, and phases that halt growth are not realized. Here, we propose a simple, coarse-grained cell model that includes inhibitor molecule species in addition to the autocatalytic active protein. The inhibitor forms a complex with active proteins to suppress the catalytic process. Depending on the nutrient condition, the model exhibits the typical transition a...
Theory of Temperature Dependence of the Magnetization in Rare-Earth-Transition-Metal Alloys
DEFF Research Database (Denmark)
Szpunar, B.; Lindgård, Per-Anker
1977-01-01
It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures for Gdl-xTx (T = Co, Ni, and Fe) and Y1-xCox can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition-metal pseudo-spin......1-xCox durch ein einfaches Model1 erklärt werden können, das eine RKKY-Wechsel-wirkung zwischen den Momenten der Seltenen Erden und des Pseudo-Spins des Übergangsmetalls annimmt. Die Wechselwirkung wird durch ein effektives Legierungsmedium übermittelt, das mit der CPA-Theorie und elliptischen...
On the uniqueness of t->0+ quantum transition-state theory
Hele, Timothy J H
2013-01-01
It was shown recently that there exists a true quantum transition-state theory (QTST) corresponding to the t->0+ limit of a (new form of) quantum flux-side time-correlation function. Remarkably, this QTST is identical to ring-polymer molecular dynamics (RPMD) TST. Here we provide evidence which suggests very strongly that this QTST (= RPMD-TST) is unique, in the sense that the t->0+ limit of any other flux-side time-correlation function gives either non-positive-definite quantum statistics or zero. We introduce a generalized flux-side time-correlation function which includes all other (known) flux-side time-correlation functions as special limiting cases. We find that the only non-zero t->0+ limit of this function that contains positive-definite quantum statistics is RPMD-TST.
Directory of Open Access Journals (Sweden)
Yang Zhijie
2016-01-01
Full Text Available Most existing project assessment relies on expert scoring, whose precision can be deteriorated by personal subjectivity. This paper presents an assessment method to compare the advantages and disadvantages of three cohesion patterns between suburban and urban rail transit network, which reduces the influence of subjective score. A modified rough set – grey correlation model is developed as a core of this assessment, based on the integration of rough set theory and grey correlational analysis, where an index system is set up for model calculation. A case study using the network in Ningbo is applied to demonstrate the effectiveness of the method, the results show that the method is more effective using discretely distributed data sensitive to sample size. The consistency of the results in comparison with marginal cost analysis can be a preliminary verification of the model.
Jump Markov models and transition state theory: the Quasi-Stationary Distribution approach
Di Gesù, Giacomo; Peutrec, Dorian Le; Nectoux, Boris
2016-01-01
We are interested in the connection between a metastable continuous state space Markov process (satisfying e.g. the Langevin or overdamped Langevin equation) and a jump Markov process in a discrete state space. More precisely, we use the notion of quasi-stationary distribution within a metastable state for the continuous state space Markov process to parametrize the exit event from the state. This approach is useful to analyze and justify methods which use the jump Markov process underlying a metastable dynamics as a support to efficiently sample the state-to-state dynamics (accelerated dynamics techniques). Moreover, it is possible by this approach to quantify the error on the exit event when the parametrization of the jump Markov model is based on the Eyring-Kramers formula. This therefore provides a mathematical framework to justify the use of transition state theory and the Eyring-Kramers formula to build kinetic Monte Carlo or Markov state models.
Schickling, Tobias; Bünemann, Jörg; Gebhard, Florian; Boeri, Lilia
2016-05-01
We use the Gutzwiller density-functional theory to calculate ground-state properties and band structures of iron in its body-centered-cubic (bcc) and hexagonal-close-packed (hcp) phases. For a Hubbard interaction U =9 eV and Hund's-rule coupling J =0.54 eV , we reproduce the lattice parameter, magnetic moment, and bulk modulus of bcc iron. For these parameters, bcc is the ground-state lattice structure at ambient pressure up to a pressure of pc=41 GPa where a transition to the nonmagnetic hcp structure is predicted, in qualitative agreement with experiment (pcexp=10 ,...,15 GPa ) . The calculated band structure for bcc iron is in good agreement with ARPES measurements. The agreement improves when we perturbatively include the spin-orbit coupling.
Transition state theory: a generalization to nonequilibrium systems with power-law distributions
Jiulin, Du
2011-01-01
Transition state theory (TST) is generalized for the nonequilibrium system with power-law distributions. The stochastic dynamics that gives rise to the power-law distributions for the reaction coordinate and momentum is modeled by the Langevin equations and corresponding Fokker-Planck equations. It is assumed that the system far away from equilibrium has not to relax to a thermal equilibrium state with Boltzmann-Gibbs distribution, but asymptotically approaches to a nonequilibrium stationary-state with power-law distributions. Thus, we obtain a generalization of TST rates to nonequilibrium systems with power-law distributions. Furthermore, we derive the generalized TST rate constants for one-dimension and n-dimension Hamiltonian systems away from equilibrium, and receive a generalized Arrhenius rate for the system with power-law distributions.
Institute of Scientific and Technical Information of China (English)
王艳; 钱英; 冯文林; 刘若庄
2003-01-01
An implementation of the variational quantum RRKM program is presented to utilize the direct ab initio dynamics approach for calculating k(E, J), k(E) and k(T) within the framework of the microcanonical transition state (μTST) and microcanonical variational TST (μVT) theories. An algorithm including tunneling contributions in Beyer-Swinehart method for calculating microcanonical rate constants is also proposed. An efficient piece-wise interpolation method is developed to evaluate the Boltzmann integral in calculation of thermal rate constants. Calculations on several test reactions, namely the H(D)2CO→H(D)2 + CO, CH2CO→CH2 + CO and CH4 + H→CH3 + H2 reactions, show that the results are in good agreement with the previous rate constants calculations. This approach would require much less computational resource.
Directory of Open Access Journals (Sweden)
Paulo de Tarso Almeida Paiva
2005-12-01
Full Text Available As relações entre crescimento populacional e desenvolvimento desafiam estudiosos por muito tempo e referem-se tanto aos impactos do crescimento e estrutura da população sobre o crescimento e a distribuição da renda (crescimento econômico, quanto sobre os impactos do crescimento econômico sobre o crescimento e a estrutura da população. Há cerca de três décadas discutiam-se as causas e conseqüências do crescimento populacional. Hoje, discutem-se as causas e conseqüências da transição demográfica. Muita coisa mudou no mundo e, do ponto de vista demográfico, a maior mudança foi a universalização do processo de transição demográfica. Expressões como "bomba demográfica" foram substituídas por "bônus demográfico" ou "janela de oportunidades". Este artigo pretende examinar como essas relações entre população e economia foram interpretadas e discutidas e como influenciaram o pensamento, a pesquisa acadêmica e, eventualmente, algumas propostas de políticas públicas no Brasil. O artigo procura sumariar os avanços que estão em curso na pesquisa sobre população e economia e suas implicações para as políticas públicas e o desenvolvimento.Relationships between development and population growth have challenged scholars and researchers for many years, and refer to the impacts of population growth and distribution on economic growth, and to the impacts of economic growth on population. Three decades ago the major issue was the causes and consequences of population growth. The central issue today is about the causes and consequences of demographic transition on the economy. Many changes have taken place over the last thirty years. From the demographic point of view, the most important change has been the generalization of the so-called demographic transition. "Demographic bonus" and "window of opportunities" have become substitutes for "the demographic bomb." This article describes how the relations between population
Landau theory description of observed isotropic to anisotropic phase transition in mixed clay gels
Pujala, Ravi Kumar; Pawar, Nisha; Bohidar, H. B.
2011-05-01
A characteristic new cooperative dehydration transition, in 1:1 Laponite-MMT cogel, was observed at Tc ≈ 60 °C, a temperature at which the storage modulus (G') and depolarization ratio (Dp) showed sharp increase, and the isotropic cogel turned into an anisotropic one. The dehydration dynamics could be described through power-law relations: G' ˜ (Tc - T)-γ and Dp ˜ (Tc - T)-β with γ ≈ β = 0.40 ± 0.05. The x-ray diffraction data revealed that the crystallite size decreased from 17 nm (at 20 °C) to 10 nm (at 80 °C) implying loss of free and inter-planar water. When this cogel was spontaneously cooled below Tc, it exhibited much larger storage modulii values which implied the existence of several metastable states in this system. This phase transition could be modeled through Landau theory, where the depolarization ratio was used as experimental order parameter (ψ). This parameter was found to scale with temperature, as ψ ˜ (Tc - T)-α, with power-law exponent α = 0.40 ± 0.05; interestingly, we found α ≈ β ≈ γ.
Mökkönen, Harri; Jónsson, Hannes
2016-01-01
The recrossing correction to the transition state theory estimate of a thermal rate can be difficult to calculate when the energy barrier is flat. This problem arises, for example, in polymer escape if the polymer is long enough to stretch between the initial and final state energy wells while the polymer beads undergo diffusive motion back and forth over the barrier. We present an efficient method for evaluating the correction factor by constructing a sequence of hyperplanes starting at the transition state and calculating the probability that the system advances from one hyperplane to another towards the product. This is analogous to what is done in forward flux sampling except that there the hyperplane sequence starts at the initial state. The method is applied to the escape of polymers with up to 64 beads from a potential well. For high temperature, the results are compared with direct Langevin dynamics simulations as well as forward flux sampling and excellent agreement between the three rate estimates i...
Theory of activated dynamics and glass transition of hard colloids in two dimensions.
Zhang, Bo-kai; Li, Hui-shu; Tian, Wen-de; Chen, Kang; Ma, Yu-qiang
2014-03-07
The microscopic nonlinear Langevin equation theory is applied to study the localization and activated hopping of two-dimensional hard disks in the deeply supercooled and glass states. Quantitative comparisons of dynamic characteristic length scales, barrier, and their dependence on the reduced packing fraction are presented between hard-disk and hard-sphere suspensions. The dynamic barrier of hard disks emerges at higher absolute and reduced packing fractions and correspondingly, the crossover size of the dynamic cage which correlates to the Lindemann length for melting is smaller. The localization lengths of both hard disks and spheres decrease exponentially with packing fraction. Larger localization length of hard disks than that of hard spheres is found at the same reduced packing fraction. The relaxation time of hard disks rises dramatically above the reduced packing fraction of 0.88, which leads to lower reduced packing fraction at the kinetic glass transition than that of hard spheres. The present work provides a foundation for the subsequent study of the glass transition of binary or polydisperse mixtures of hard disks, normally adopted in experiments and simulations to avoid crystallization, and further, the rheology and mechanical response of the two-dimensional glassy colloidal systems.
Energy Technology Data Exchange (ETDEWEB)
Lorquet, J. C., E-mail: jc.lorquet@ulg.ac.be [Department of Chemistry, University of Liège, Sart-Tilman (Bâtiment B6), B-4000 Liège 1 (Belgium)
2015-09-14
The purpose of the present work is to determine initial conditions that generate reacting, recrossing-free trajectories that cross the conventional dividing surface of transition state theory (i.e., the plane in configuration space passing through a saddle point of the potential energy surface and perpendicular to the reaction coordinate) without ever returning to it. Local analytical equations of motion valid in the neighborhood of this planar surface have been derived as an expansion in Poisson brackets. We show that the mere presence of a saddle point implies that reactivity criteria can be quite simply formulated in terms of elements of this series, irrespective of the shape of the potential energy function. Some of these elements are demonstrated to be equal to a sum of squares and thus to be necessarily positive, which has a profound impact on the dynamics. The method is then applied to a three-dimensional model describing an atom-diatom interaction. A particular relation between initial conditions is shown to generate a bundle of reactive trajectories that form reactive cylinders (or conduits) in phase space. This relation considerably reduces the phase space volume of initial conditions that generate recrossing-free trajectories. Loci in phase space of reactive initial conditions are presented. Reactivity is influenced by symmetry, as shown by a comparative study of collinear and bent transition states. Finally, it is argued that the rules that have been derived to generate reactive trajectories in classical mechanics are also useful to build up a reactive wave packet.
Holland, J Nathaniel; DeAngelis, Donald L
2009-12-01
Interactions between two populations are often defined by their interaction outcomes; that is, the positive, neutral, or negative effects of species on one another. Yet, signs of outcomes are not absolute, but vary with the biotic and abiotic contexts of interactions. Here, we develop a general theory for transitions between outcomes based on consumer-resource (C-R) interactions in which one or both species exploit the other as a resource. Simple models of C-R interactions revealed multiple equilibria, including one for species coexistence and others for extinction of one or both species, indicating that species' densities alone could determine the fate of interactions. All possible outcomes [(+ +), (+ -), (--), (+ 0), (- 0), (0 0)] of species coexistence emerged merely through changes in parameter values of C-R interactions, indicating that variation in C-R interactions resulting from biotic and abiotic conditions could determine shifts in outcomes. These results suggest that C-R interactions can provide a broad mechanism for understanding context- and density-dependent transitions between interaction outcomes.
Consumer-resource theory predicts dynamic transitions between outcomes of interspecific interactions
Holland, J. Nathaniel; DeAngelis, Donald L.
2009-01-01
Interactions between two populations are often defined by their interaction outcomes; that is, the positive, neutral, or negative effects of species on one another. Yet, signs of outcomes are not absolute, but vary with the biotic and abiotic contexts of interactions. Here, we develop a general theory for transitions between outcomes based on consumer-resource (C-R) interactions in which one or both species exploit the other as a resource. Simple models of C-R interactions revealed multiple equilibria, including one for species coexistence and others for extinction of one or both species, indicating that species densities alone could determine the fate of interactions. All possible outcomes (+ +), (+ -), (- -), (+ 0), (- 0), (0 0) of species coexistence emerged merely through changes in parameter values of C-R interactions, indicating that variation in C-R interactions resulting from biotic and abiotic conditions could determine shifts in outcomes. These results suggest that C-R interactions can provide a broad mechanism for understanding context- and density-dependent transitions between interaction outcomes.
Phase Transition Couplings in U(1) and SU(N) Regularized Gauge Theories
Laperashvili, L. V.; Ryzhikh, D. A.; Nielsen, H. B.
Using a two-loop approximation for β functions, we have considered the corresponding renormalization group improved effective potential in the dual Abelian Higgs model (DAHM) of scalar monopoles and calculated the phase transition (critical) couplings in U(1) and SU(N) regularized gauge theories. In contrast to our previous result αcrit 0.17, obtained in the one-loop approximation with the DAHM effective potential (see Ref. 20), the critical value of the electric fine structure constant in the two-loop approximation, calculated in the present paper, is equal to αcrit 0.208 and coincides with the lattice result for compact QED10: α crit lat≈ 0.20+/- 0.015. Following the 't Hooft's idea of the ``Abelization'' of monopole vacuum in the Yang-Mills theories, we have obtained an estimation of the SU(N) triple point coupling constants, which is α {N, crit}-1= (N)/(2) √ {(N+1)/(N-1)} α { U(1),crit}-1. This relation was used for the description of the Planck scale values of the inverse running constants α i-1(μ ) (i= 1, 2, 3 correspond to U(1), SU(2) and SU(3) groups), according to the ideas of the multiple point model.16
Phase Transition Couplings in U(1) and SU(N) Regulirized Gauge Theories
Laperashvili, L V; Ryzhikh, D A
2001-01-01
Using a 2-loop approximation for $\\beta$-functions, we have considered the corresponding renormalization group improved effective potential in the Dual Abelian Higgs Model (DAHM) of scalar monopoles and calculated the phase transition (critical) couplings in U(1) and SU(N) regularized gauge theories. In contrast to our previous result $\\alpha_{crit} \\approx 0.17$, obtained in the one-loop approximation with the DAHM effective potential (see Ref.[20]), the critical value of the electric fine structure constant in the 2-loop approximation, calculated in the present paper, is equal to $\\alpha_{crit}\\approx 0.208$ and coincides with the lattice result for compact QED [10]: $\\alpha_{crit}^{lat} \\approx 0.20\\pm 0.015$. Following the 't Hooft's idea of the "abelization" of monopole vacuum in the Yang--Mills theories, we have obtained an estimation of the SU(N) triple point coupling constants, which is $\\alpha_{N,crit}^{-1}=\\frac{N}{2}\\sqrt{\\frac{N+1}{N-1}} \\alpha_{U(1),crit}^{-1}$. This relation was used for the des...
Seo, Dong-Kyun
2007-11-14
We present a theoretical scheme for a semiquantitative analysis of electronic structures of magnetic transition metal dimer complexes within spin density functional theory (DFT). Based on the spin polarization perturbational orbital theory [D.-K. Seo, J. Chem. Phys. 125, 154105 (2006)], explicit spin-dependent expressions of the spin orbital energies and coefficients are derived, which allows to understand how spin orbitals form and change their energies and shapes when two magnetic sites are coupled either ferromagnetically or antiferromagnetically. Upon employment of the concept of magnetic orbitals in the active-electron approximation, a general mathematical formula is obtained for the magnetic coupling constant J from the analytical expression for the electronic energy difference between low-spin broken-symmetry and high-spin states. The origin of the potential exchange and kinetic exchange terms based on the one-electron picture is also elucidated. In addition, we provide a general account of the DFT analysis of the magnetic exchange interactions in compounds for which the active-electron approximation is not appropriate.
Greene, Samuel M; Shan, Xiao; Clary, David C
2016-06-28
Semiclassical Transition State Theory (SCTST), a method for calculating rate constants of chemical reactions, offers gains in computational efficiency relative to more accurate quantum scattering methods. In full-dimensional (FD) SCTST, reaction probabilities are calculated from third and fourth potential derivatives along all vibrational degrees of freedom. However, the computational cost of FD SCTST scales unfavorably with system size, which prohibits its application to larger systems. In this study, the accuracy and efficiency of 1-D SCTST, in which only third and fourth derivatives along the reaction mode are used, are investigated in comparison to those of FD SCTST. Potential derivatives are obtained from numerical ab initio Hessian matrix calculations at the MP2/cc-pVTZ level of theory, and Richardson extrapolation is applied to improve the accuracy of these derivatives. Reaction barriers are calculated at the CCSD(T)/cc-pVTZ level. Results from FD SCTST agree with results from previous theoretical and experimental studies when Richardson extrapolation is applied. Results from our implementation of 1-D SCTST, which uses only 4 single-point MP2/cc-pVTZ energy calculations in addition to those for conventional TST, agree with FD results to within a factor of 5 at 250 K. This degree of agreement and the efficiency of the 1-D method suggest its potential as a means of approximating rate constants for systems too large for existing quantum scattering methods.
Energy Technology Data Exchange (ETDEWEB)
Singh, Ram Chandra [Department of Physics, Hindustan Institute of Technology, 32, 34 Knowledge Park-III, Greater Noida-201306, UP (India)
2007-09-19
We have used the density-functional theory to study the effect of varying temperature on the isotropic-nematic transition of a fluid of molecules interacting via the Gay-Berne intermolecular potential. The nematic phase is found to be stable with respect to isotropic phase in the temperature range 0.80{<=}T*{<=}1.25. Pair correlation functions needed as input information in density-functional theory is calculated using the Percus-Yevick integral equation theory. We find that the density-functional theory is good for studying the isotropic-nematic transition in molecular fluids if the values of the pair-correlation functions in the isotropic phase are known accurately. We have also compared our results with computer simulation results wherever they are available.
Barnes, Rory
2013-01-01
The determination of an exoplanet as rocky is critical for the assessment of planetary habitability. Observationally, the number of small-radius, transiting planets with accompanying mass measurements is insufficient for a robust determination of the transitional mass or radius. Theoretically, models predict that rocky planets can grow large enough to become gas giants when they reach ~10 Earth-masses, but the transitional mass remains unknown. Here I show how transit data, interpreted in the context of tidal theory, can reveal the critical radius that separates rocky and gaseous exoplanets. Standard tidal models predict that rocky exoplanets' orbits are tidally circularized much more rapidly than gaseous bodies', suggesting the former will tend to be found on circular orbits at larger semi-major axes than the latter. Well-sampled transits can provide a minimum eccentricity of the orbit, allowing a measurement of this differential circularization. I show that this effect should be present in the data from the...
Metastability of the Nonlinear Wave Equation: Insights from Transition State Theory
Newhall, Katherine A.; Vanden-Eijnden, Eric
2017-06-01
This paper is concerned with the longtime dynamics of the nonlinear wave equation in one-space dimension, u_{tt} - κ ^2 u_{xx} +V'(u) =0 \\quad x\\in [0,1] where κ >0 is a parameter and V( u) is a potential bounded from below and growing at least like u^2 as |u|→ ∞. Infinite energy solutions of this equation preserve a natural Gibbsian invariant measure, and when the potential is double-welled, for example when V(u) = 1/4 (1-u^2)^2, there is a regime such that two small disjoint sets in the system's phase-space concentrate most of the mass of this measure. This suggests that the solutions to the nonlinear wave equation can be metastable over these sets, in the sense that they spend long periods of time in these sets and only rarely transition between them. Here, we quantify this phenomenon by calculating exactly via transition state theory (TST) the mean frequency at which the solutions of the nonlinear wave equation with initial conditions drawn from its invariant measure cross a dividing surface lying in between the metastable sets. We also investigate numerically how the mean TST frequency compares to the rate at which a typical solution crosses this dividing surface. These numerical results suggest that the dynamics of the nonlinear wave equation is ergodic and rapidly mixing with respect to the Gibbs invariant measure when the parameter κ in small enough. In this case, successive transitions between the two regions are roughly uncorrelated and their dynamics can be coarse-grained to jumps in a two-state Markov chain whose rate can be deduced from the mean TST frequency. This is a regime in which the dynamics of the nonlinear wave equation displays a metastable behavior that is not fundamentally different from that observed in its stochastic counterpart in which random noise and damping terms are added to the equation. For larger κ , however, the dynamics either stops being ergodic, or its mixing time becomes larger than the inverse of the TST frequency
Metastability of the Nonlinear Wave Equation: Insights from Transition State Theory
Newhall, Katherine A.; Vanden-Eijnden, Eric
2017-01-01
This paper is concerned with the longtime dynamics of the nonlinear wave equation in one-space dimension, u_{tt} - κ^2 u_{xx} +V'(u) =0 quad xin [0,1] where κ >0 is a parameter and V(u) is a potential bounded from below and growing at least like u^2 as |u|→ ∞. Infinite energy solutions of this equation preserve a natural Gibbsian invariant measure, and when the potential is double-welled, for example when V(u) = 1/4 (1-u^2)^2 , there is a regime such that two small disjoint sets in the system's phase-space concentrate most of the mass of this measure. This suggests that the solutions to the nonlinear wave equation can be metastable over these sets, in the sense that they spend long periods of time in these sets and only rarely transition between them. Here, we quantify this phenomenon by calculating exactly via transition state theory (TST) the mean frequency at which the solutions of the nonlinear wave equation with initial conditions drawn from its invariant measure cross a dividing surface lying in between the metastable sets. We also investigate numerically how the mean TST frequency compares to the rate at which a typical solution crosses this dividing surface. These numerical results suggest that the dynamics of the nonlinear wave equation is ergodic and rapidly mixing with respect to the Gibbs invariant measure when the parameter κ in small enough. In this case, successive transitions between the two regions are roughly uncorrelated and their dynamics can be coarse-grained to jumps in a two-state Markov chain whose rate can be deduced from the mean TST frequency. This is a regime in which the dynamics of the nonlinear wave equation displays a metastable behavior that is not fundamentally different from that observed in its stochastic counterpart in which random noise and damping terms are added to the equation. For larger κ, however, the dynamics either stops being ergodic, or its mixing time becomes larger than the inverse of the TST frequency
Sharma, Bharati; Giri, Gayatri; Christensson, Kyllike; K V, Ramani; Johansson, Eva
2013-10-03
Under the National Rural Health Mission, the current emphasis is on achieving universal institutional births through incentive schemes as part of reforms related to childbirth in India. There has been rapid progress in achieving this goal. To understand the choices made as well as practices and perceptions related to childbirth amongst tribal women in Gujarat and how these have been influenced by modernity in general and modernity brought in through maternal health policies. A model depicting the transition in childbirth practices amongst tribal women was constructed using the grounded theory approach with; 8 focus groups of women, 5 in depth interviews with traditional birth attendants, women, and service providers and field notes on informal discussions and observations. A transition in childbirth practices across generations was noted, i.e. a shift from home births attended by Traditional Birth Attendants (TBAs) to hospital births. The women and their families both adapted to and shaped this transition through a constant 'trade-off between desirable and essential'- the desirable being a traditional homebirth in secure surroundings and the essential being the survival of mother and baby by going to hospital. This transition was shaped by complex multiple factors: 1) Overall economic growth and access to modern medical care influencing women's choices, 2) External context in terms of the international maternal health discourses and national policies, especially incentive schemes for promoting institutional deliveries, 3) Socialisation into medical childbirth practices, through exposure to many years of free outreach services for maternal and child health, 4) Loss of self reliance in the community as a consequence of role redefinition and deskilling of the TBAs and 5) Cultural belief that intervention is necessary during childbirth aiding easy acceptance of medical interventions. In resource poor settings where choices are limited and mortality is high, hospital
Demographic changes and international factor mobility
2004-01-01
This paper reviews the extent and policy implications of linkages between demographic changes and international factor mobility. Evidence is found of significant demographic effects on both migration and the current account, but for different reasons neither increased migration nor international transfers of savings is expected to offer much assistance in digesting the variety of demographic transitions expected over the next fifty years. The paper also examines more briefly the effects of de...
Direct simulation of groundwater transit-time distributions using the reservoir theory
Etcheverry, David; Perrochet, Pierre
Groundwater transit times are of interest for the management of water resources, assessment of pollution from non-point sources, and quantitative dating of groundwaters by the use of environmental isotopes. The age of water is the time water has spent in an aquifer since it has entered the system, whereas the transit time is the age of water as it exits the system. Water at the outlet of an aquifer is a mixture of water elements with different transit times, as a consequence of the different flow-line lengths. In this paper, transit-time distributions are calculated by coupling two existing methods, the reservoir theory and a recent age-simulation method. Based on the derivation of the cumulative age distribution over the whole domain, the approach accounts for the whole hydrogeological framework. The method is tested using an analytical example and its applicability illustrated for a regional layered aquifer. Results show the asymmetry and multimodality of the transit-time distribution even in advection-only conditions, due to the aquifer geometry and to the velocity-field heterogeneity. Résumé Les temps de transit des eaux souterraines sont intéressants à connaître pour gérer l'évaluation des ressources en eau dans le cas de pollution à partir de sources non ponctuelles, et aussi pour dater quantitativement les eaux souterraines au moyen des isotopes du milieu. L'âge de l'eau est le temps qu'elle a passé dans un aquifère depuis qu'elle est entrée dans le système, alors que le temps de transit est l'âge de l'eau au moment où elle quitte le système. L'eau à la sortie d'un aquifère est un mélange d'eaux possédant différents temps de transit, du fait des longueurs différentes des lignes de courant suivies. Dans ce papier, les distributions des temps de transit sont calculées en couplant deux méthodes, la théorie du réservoir et une méthode récente de simulation des âges. Basée sur la dérivation de la distribution cumulées des âges sur
Directory of Open Access Journals (Sweden)
J.E. García-Ramos
2014-09-01
Full Text Available We introduce the basic concepts of catastrophe theory needed to derive analytically the phase diagram of the proton–neutron interacting boson model (IBM-2. Previous studies [1–3] were based on numerical solutions. We here explain the whole IBM-2 phase diagram including the precise order of the phase transitions in terms of the cusp catastrophe.
DEFF Research Database (Denmark)
Hummelshøj, Jens Strabo; Landis, David; Voss, Johannes
2009-01-01
We present a computational screening study of ternary metal borohydrides for reversible hydrogen storage based on density functional theory. We investigate the stability and decomposition of alloys containing 1 alkali metal atom, Li, Na, or K (M1); and 1 alkali, alkaline earth or 3d/4d transition...
Energy Technology Data Exchange (ETDEWEB)
García-Ramos, J.E., E-mail: enrique.ramos@dfaie.uhu.es [Departamento de Física Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Unidad Asociada de la Universidad de Huelva al IEM (CSIC), Madrid (Spain); Arias, J.M., E-mail: ariasc@us.es [Departamento de Física Atómica, Molecular y Nuclear, Universidad de Sevilla, Apdo 1065, 41080 Sevilla (Spain); Unidad Asociada de la Universidad de Sevilla al IEM (CSIC), Madrid (Spain); Dukelsky, J., E-mail: dukelsky@iem.cfmac.csic.es [Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid (Spain)
2014-09-07
We introduce the basic concepts of catastrophe theory needed to derive analytically the phase diagram of the proton–neutron interacting boson model (IBM-2). Previous studies [1–3] were based on numerical solutions. We here explain the whole IBM-2 phase diagram including the precise order of the phase transitions in terms of the cusp catastrophe.
Dan, Jia Kun; Huang, Xian Bin; Ren, Xiao Dong; Wei, Bing
2017-08-01
A theoretical model referring to mode selection of Z-pinch-driven magneto-Rayleigh-Taylor (MRT) instability, which explains the generation of fundamental instability mode and evolution of fundamental wavelength in experiments, is proposed on the basis of the Landau theory of phase transition. The basic idea of this phase transition model lies in that the appearance of MRT instability pattern can be considered as a consequence of the spontaneous generation of interfacial structure like the spontaneous magnetization in a ferromagnetic system. It is demonstrated that the amplitude of instability is responsible for the order parameter in the Landau theory of phase transition and the fundamental wavelength appears to play a role analogous to inverse temperature in thermodynamics. Further analysis indicates that the MRT instability is characterized by first order phase transition and the fundamental wavelength is proportional to the square root of energy entering into the system from the driving source. The theory predicts that the fundamental wavelength grows rapidly and saturates reaching a limiting wavelength of the order of the liner's final outer radius. The results given by this theory show qualitative agreement with the available experimental data of MRT instability of liner implosions conducted on the Sandia Z machine as well as Primary Test Stand facility at the Institute of Fluid Physics.
Narumi, Takayuki; Tokuyama, Michio
2017-03-01
For short-range attractive colloids, the phase diagram of the kinetic glass transition is studied by time-convolutionless mode-coupling theory (TMCT). Using numerical calculations, TMCT is shown to recover all the remarkable features predicted by the mode-coupling theory for attractive colloids: the glass-liquid-glass reentrant, the glass-glass transition, and the higher-order singularities. It is also demonstrated through the comparisons with the results of molecular dynamics for the binary attractive colloids that TMCT improves the critical values of the volume fraction. In addition, a schematic model of three control parameters is investigated analytically. It is thus confirmed that TMCT can describe the glass-glass transition and higher-order singularities even in such a schematic model.
Liminality in cultural transition: applying ID-EA to advance a concept into theory-based practice.
Baird, Martha B; Reed, Pamela G
2015-01-01
As global migration increases worldwide, nursing interventions are needed to address the effects of migration on health. The concept of liminality emerged as a pivotal concept in the situation-specific theory of well-being in refugee women experiencing cultural transition. As a relatively new concept in the discipline of nursing, liminality is explored using a method, called ID-EA, which we developed to advance a theoretical concept for application to nursing practice. Liminality in the context of cultural transition is further developed using the five steps of inquiry of the ID-EA method. The five steps are as follows: (1) inductive inquiry: qualitative research, (2) deductive inquiry: literature review, (3) synthesis of inductive and deductive inquiry, (4) evaluation inquiry, and (5) application-to-practice inquiry. The overall goal of this particular work was to develop situation-specific, theory-based interventions that facilitate cultural transitions for immigrants and refugees.
Zhong, Fan; Chen, Qizhou
2005-10-21
Phase transitions are of great importance in a diversity of fields. They are usually classified into continuous phase transitions and first-order phase transitions (FOPTs). Whereas the former has a well-developed theoretical framework of the renormalization-group (RG) theory, no general theory has yet been developed for the latter that appear far more frequently. Focusing on the dynamics of a generic FOPT in the phi4 model below its critical point, we show by a field-theoretic RG method that it is governed by an unexpected unstable fixed point of the corresponding phi3 model. Accordingly, it exhibits a distinct scaling and universality behavior with unstable exponents different from the critical ones.
Uni-directional consumer-resource theory characterizing transitions of interaction outcomes
Wang, Y.; DeAngelis, D.L.; Holland, J.N.
2011-01-01
A resource is considered here to be a biotic population that helps to maintain the population growth of its consumers, whereas a consumer utilizes a resource and in turn decreases its growth rate. Bi-directional consumer-resource (C-R) interactions have been the object of recent theory. In these interactions, each species acts, in some respects, as both a consumer and a resource of the other, which is the basis of many mutualisms. In uni-directional C-R interactions between two species, one acts as a consumer and the other as a material and/or energy resource, while neither acts as both. The relationship between insect pollinator/seed parasites and the host plant is an example of the latter interaction type of C-R, as the insect provides no material resource to the plant (though it provides a pollination service). In this paper we consider a different variation of the uni-directional C-R interaction, in which the resource species has both positive and negative effects on the consumer species, while the consumer has only a negative effect on the resource. A predator-prey system in which the prey is able to kill or consume predator eggs or larvae is an example. Our aim is to demonstrate mechanisms by which interaction outcomes of this system vary with different conditions, and thus to extend the uni-directional C-R theory established by Holland and DeAngelis (2009). By the analysis of a specific two-species system, it is shown that there is no periodic solution of the system, and the parameter (factor) space can be divided into six regions, which correspond to predation/parasitism, amensalism, and competition. The interaction outcomes of the system transition smoothly when the parameters are changed continuously in the six regions and/or initial densities of the species vary in a smooth fashion. Varying a pair of parameters can also result in the transitions. The analysis leads to both conditions under which the species approach their maximal densities, and
Bao, Junwei Lucas; Zhang, Xin; Truhlar, Donald G
2016-11-29
Bond dissociation is a fundamental chemical reaction, and the first principles modeling of the kinetics of dissociation reactions with a monotonically increasing potential energy along the dissociation coordinate presents a challenge not only for modern electronic structure methods but also for kinetics theory. In this work, we use multifaceted variable-reaction-coordinate variational transition-state theory (VRC-VTST) to compute the high-pressure limit dissociation rate constant of tetrafluoroethylene (C2F4), in which the potential energies are computed by direct dynamics with the M08-HX exchange correlation functional. To treat the pressure dependence of the unimolecular rate constants, we use the recently developed system-specific quantum Rice-Ramsperger-Kassel theory. The calculations are carried out by direct dynamics using an exchange correlation functional validated against calculations that go beyond coupled-cluster theory with single, double, and triple excitations. Our computed dissociation rate constants agree well with the recent experimental measurements.
Itinerant type many-body theories for photo-induced structural phase transitions
Nasu, Keiichiro
2004-09-01
Itinerant type quantum many-body theories for photo-induced structural phase transitions (PSPTs) are reviewed in close connection with various recent experimental results related to this new optical phenomenon. There are two key concepts: the hidden multi-stability of the ground state, and the proliferations of optically excited states. Taking the ionic (I) rarr neutral (N) phase transition in the organic charge transfer (CT) crystal, TTF-CA, as a typical example for this type of transition, we, at first, theoretically show an adiabatic path which starts from CT excitons in the I-phase, but finally reaches an N-domain with a macroscopic size. In connection with this I-N transition, the concept of the initial condition sensitivity is also developed so as to clarify experimentally observed nonlinear characteristics of this material. In the next, using a more simplified model for the many-exciton system, we theoretically study the early time quantum dynamics of the exciton proliferation, which finally results in the formation of a domain with a large number of excitons. For this purpose, we derive a stepwise iterative equation to describe the exciton proliferation, and clarify the origin of the initial condition sensitivity. Possible differences between a photo-induced nonequilibrium phase and an equilibrium phase at high temperatures are also clarified from general and conceptional points of view, in connection with recent experiments on the photo-induced phase transition in an organo-metallic complex crystal. It will be shown that the photo-induced phase can make a new interaction appear as a broken symmetry only in this phase, even when this interaction is almost completely hidden in all the equilibrium phases, such as the ground state and other high-temperature phases. The relation between the photo-induced nonequilibrium phase and the hysteresis induced nonequilibrium one is also qualitatively discussed. We will be concerned with a macroscopic parity violation
Itinerant type many-body theories for photo-induced structural phase transitions
Energy Technology Data Exchange (ETDEWEB)
Nasu, Keiichiro [Solid State Theory Division, Institute of Materials Structure Science, KEK, Graduate University for Advanced Study, 1-1, Oho, Tsukuba, Ibaraki, 305-0801 (Japan)
2004-09-01
Itinerant type quantum many-body theories for photo-induced structural phase transitions (PSPTs) are reviewed in close connection with various recent experimental results related to this new optical phenomenon. There are two key concepts: the hidden multi-stability of the ground state, and the proliferations of optically excited states. Taking the ionic (I) {yields} neutral (N) phase transition in the organic charge transfer (CT) crystal, TTF-CA, as a typical example for this type of transition, we, at first, theoretically show an adiabatic path which starts from CT excitons in the I-phase, but finally reaches an N-domain with a macroscopic size. In connection with this I-N transition, the concept of the initial condition sensitivity is also developed so as to clarify experimentally observed nonlinear characteristics of this material. In the next, using a more simplified model for the many-exciton system, we theoretically study the early time quantum dynamics of the exciton proliferation, which finally results in the formation of a domain with a large number of excitons. For this purpose, we derive a stepwise iterative equation to describe the exciton proliferation, and clarify the origin of the initial condition sensitivity. Possible differences between a photo-induced nonequilibrium phase and an equilibrium phase at high temperatures are also clarified from general and conceptional points of view, in connection with recent experiments on the photo-induced phase transition in an organo-metallic complex crystal. It will be shown that the photo-induced phase can make a new interaction appear as a broken symmetry only in this phase, even when this interaction is almost completely hidden in all the equilibrium phases, such as the ground state and other high-temperature phases. The relation between the photo-induced nonequilibrium phase and the hysteresis induced nonequilibrium one is also qualitatively discussed. We will be concerned with a macroscopic parity
Greene, Samuel M.; Shan, Xiao; Clary, David C.
2016-02-01
We investigate which terms in Reduced-Dimensionality Semiclassical Transition State Theory (RD SCTST) contribute most significantly in rate constant calculations of hydrogen extraction and exchange reactions of hydrocarbons. We also investigate the importance of deep tunneling corrections to the theory. In addition, we introduce a novel formulation of the theory in Jacobi coordinates. For the reactions of H atoms with methane, ethane, and cyclopropane, we find that a one-dimensional (1-D) version of the theory without deep tunneling corrections compares well with 2-D SCTST results and accurate quantum scattering results. For the "heavy-light-heavy" H atom exchange reaction between CH3 and CH4, deep tunneling corrections are needed to yield 1-D results that compare well with 2-D results. The finding that accurate rate constants can be obtained from derivatives of the potential along only one dimension further validates RD SCTST as a computationally efficient yet accurate rate constant theory.
Towards a critical transition theory under different temporal scales and noise strengths.
Shi, Jifan; Li, Tiejun; Chen, Luonan
2016-03-01
The mechanism of critical phenomena or critical transitions has been recently studied from various aspects, in particular considering slow parameter change and small noise. In this article, we systematically classify critical transitions into three types based on temporal scales and noise strengths of dynamical systems. Specifically, the classification is made by comparing three important time scales τ(λ), τ(tran), and τ(ergo), where τ(λ) is the time scale of parameter change (e.g., the change of environment), τ(tran) is the time scale when a particle or state transits from a metastable state into another, and τ(ergo) is the time scale when the system becomes ergodic. According to the time scales, we classify the critical transition behaviors as three types, i.e., state transition, basin transition, and distribution transition. Moreover, for each type of transition, there are two cases, i.e., single-trajectory transition and multitrajectory ensemble transition, which correspond to the transition of individual behavior and population behavior, respectively. We also define the critical point for each type of critical transition, derive several properties, and further propose the indicators for predicting critical transitions with numerical simulations. In addition, we show that the noise-to-signal ratio is effective to make the classification of critical transitions for real systems.
Reformulation of time-convolutionless mode-coupling theory near the glass transition
Tokuyama, Michio
2017-10-01
The time-convolutionless mode-coupling theory (TMCT) recently proposed is reformulated under the condition that one of two approximations, which have been used to formulate the original TMCT in addition to the MCT approximations done on a derivation of nonlinear memory function in terms of the intermediate-scattering function, is not employed because it causes unphysical results for intermediate times. The improved TMCT equation is then derived consistently under another approximation. It is first checked that the ergodic to non-ergodic transition obtained by a new equation is exactly the same as that obtained by an old one because the long-time dynamics of both equations coincides with each other. However, it is emphasized that a difference between them appears in the intermediate-time dynamics of physical quantities. Such a difference is explored numerically in the dynamics of a non-Gaussian parameter by employing the Percus-Yevick static structure factor to calculate the nonlinear memory function.
Wang, C; Wang, Chenyang; Preskill, John
2003-01-01
We study the +/- J random-plaquette Z_2 gauge model (RPGM) in three spatial dimensions, a three-dimensional analog of the two-dimensional +/- J random-bond Ising model (RBIM). The model is a pure Z_2 gauge theory in which randomly chosen plaquettes (occuring with concentration p) have couplings with the ``wrong sign'' so that magnetic flux is energetically favored on these plaquettes. Excitations of the model are one-dimensional ``flux tubes'' that terminate at ``magnetic monopoles.'' Electric confinement can be driven by thermal fluctuations of the flux tubes, by the quenched background of magnetic monopoles, or by a combination of the two. Like the RBIM, the RPGM has enhanced symmetry along a ``Nishimori'' line in the p-T plane (where T is the temperature). The critical concentration p_c of wrong-sign plaquettes at the confinement-Higgs phase transition along the Nishimori line can be identified with the accuracy threshold for robust storage of quantum information using topological error-correcting codes: i...
Thermodynamic Perturbation Theory for Solid-Liquid Phase Transition of Lennard-Jones Model
Institute of Scientific and Technical Information of China (English)
ZHOUShi-Qi; ZHANGXiao-Qi
2004-01-01
Both a free volume approach for Helmholtz free energy and a theoretically-based fitted formula for radial distribution function (rdf) of hard sphere solid are employed to describe the Helmholtz free energy of Lennard-Jones solid in the framework of the first order thermodynamic perturbation theory, which also is employed for the uniform Lennard Jones fluid. The dividing of the Lennard-Jones potential follows from the INCA prescription, but the specification of the equivalent hard sphere diameter is determined by a simple iteration procedure devised originally for liquid state, but extended to solid state in the present study. Two hundred shells are used in the rdf to get an accurate perturbation term.The present approach is very accurate for the description of excess Helmholtz free energy of LJ solid, but shows some deviation from the simulation for excess Helmholtz free energy of uniform LJ fluid when the reduced temperature kT/ε is higher then 5. The present approach is satisfactory for description of solid-liquid phase transition of the Lennard-Jones model.
Thermodynamic Perturbation Theory for Solid-Liquid Phase Transition of Lennard-Jones Model
Institute of Scientific and Technical Information of China (English)
ZHOU Shi-Qi; ZHANG Xiao-Qi
2004-01-01
Both a free volume approach for Helmholtz free energy and a theoretically-based fitted formula for radial distribution function (rdf) of hard sphere solid are employed to describe the Helmholtz free energy of Lennard-Jones solid in the framework of the first order thermodynamic perturbation theory, which also is employed for the uniform LennardJones fluid. The dividing of the Lennard-Jones potential follows from the WCA prescription, but the specification of the equivalent hard sphere diameter is determined by a simple iteration procedure devised originally for liquid state, but extended to solid state in the present study. Two hundred sheiks are used in the rdf to get an accurate perturbation term.The present approach is very accurate for the description of excess Helmholtz free energy of LJ solid, but shows some deviation from the simulation for excess Helmholtz free energy of uniform LJ fluid when the reduced temperature kT/ε is higher then 5. The present approach is satisfactory for description of solid-liquid phase transition of the Lennard-Jones model.
Directory of Open Access Journals (Sweden)
H. N. Fang
2013-07-01
Full Text Available The magnetic structures of iron nitrides are studied by Landau's theory of second-order phase transitions. It is found that the magnetization direction of ɛ-Fe3N must be parallel to the c-axis of the hexagonal structure, which may conclude the debates on the easy axes of ɛ-Fe3N in this field. The easy axes of α″-Fe16N2 are turned out to be along [001], or [100], or [110] direction, with the former two cases already found by the experiments. The magnetization along [111] is forbidden, which solves rigorously the puzzle why the easy axes of the α″-Fe16N2 on InGaAs and Fe are different from each other. Finally, the magnetic structure of γ′-Fe4N is also determined, and the result shows that there are three possibilities for the magnetization: parallel to the axial, or the body diagonal, or the face diagonal direction of the cubic structure, among which the first case has been found in experiments.
Chuang, Yao-Yuan
2007-08-01
Variational transition state theory with multidimensional tunneling (VTST/MT) has been used for calculating the rate constants of reactions. The updated Hessians have been used to reduce the computational costs for both geometry optimization and trajectory following procedures. In this paper, updated Hessians are used to reduce the computational costs while calculating the rate constants applying VTST/MT. Although we found that directly applying the updated Hessians will not generate good vibrational frequencies along the minimum energy path (MEP), however, we can either re-compute the full Hessian matrices at fixed intervals or calculate the Block Hessians, which is constructed by numerical one-side difference for the Hessian elements in the "critical" region and Bofill updating scheme for the rest of the Hessian elements. Due to the numerical instability of the Bofill update method near the saddle point region, we have suggested a simple strategy in which we follow the MEP until certain percentage of the classical barrier height from the barrier top with full Hessians computed and then performing rate constant calculation with the extended MEP using Block Hessians. This strategy results a mean unsigned percentage deviation (MUPD) around 10% with full Hessians computed till the point with 80% classical barrier height for four studied reactions. This proposed strategy is attractive not only it can be implemented as an automatic procedure but also speeds up the VTST/MT calculation via embarrassingly parallelization to a personal computer cluster.
The Theory of Dynamic Public Transit Priority with Dynamic Stochastic Park and Ride
Directory of Open Access Journals (Sweden)
Chengming Zhu
2014-01-01
Full Text Available Public transit priority is very important for relieving traffic congestion. The connotation of dynamic public transit priority and dynamic stochastic park and ride is presented. Based on the point that the travel cost of public transit is not higher than the travel cost of car, how to determine the level of dynamic public transit priority is discussed. The traffic organization method of dynamic public transit priority is introduced. For dynamic stochastic park and ride, layout principle, scale, and charging standard are discussed. Traveler acceptability is high through the analysis of questionnaire survey. Dynamic public transit priority with dynamic stochastic park and ride has application feasibility.
Ovchinnikov, Vasily A; Sundholm, Dage
2014-04-21
The 0-0 transitions of the electronic excitation spectra of the lowest tautomers of the four nucleotide (DNA) bases have been studied using linear-response approximate coupled-cluster singles and doubles (CC2) calculations. Excitation energies have also been calculated at the linear-response time-dependent density functional theory (TDDFT) level using the B3LYP functional. Large basis sets have been employed for ensuring that the obtained excitation energies are close to the basis-set limit. Zero-point vibrational energy corrections have been calculated at the B3LYP and CC2 levels for the ground and excited states rendering direct comparisons with high-precision spectroscopy measurements feasible. The obtained excitation energies for the 0-0 transitions of the first excited states of guanine tautomers are in good agreement with experimental values confirming the experimental assignment of the energetic order of the tautomers of the DNA bases. For the experimentally detected guanine tautomers, the first excited state corresponds to a π→π* transition, whereas for the tautomers of adenine, thymine, and the lowest tautomer of cytosine the transition to the first excited state has n →π* character. The calculations suggest that the 0-0 transitions of adenine, thymine, and cytosine are not observed in the absorption spectrum due to the weak oscillator strength of the formally symmetry-forbidden transitions, while 0-0 transitions of thymine have been detected in fluorescence excitation spectra.
Caporaso, Nicola; Cirafici, Michele; Griguolo, Luca; Pasquetti, Sara; Seminara, Domenico; Szabo, Richard J.
2006-01-01
We examine the problem of counting bound states of BPS black holes on local Calabi-Yau threefolds which are fibrations over a Riemann surface by computing the partition function of q-deformed Yang-Mills theory on the Riemann surface. We study in detail the genus zero case and obtain, at finite N, the instanton expansion of the gauge theory. It can be written exactly as the partition function for U(N) Chern-Simons gauge theory on a Lens space, summed over all non-trivial vacua, plus a tower of non-perturbative instanton contributions. The correspondence between two and three dimensional gauge theories is elucidated by an explicit mapping between two-dimensional Yang-Mills instantons and flat connections on the Lens space. In the large N limit we find a peculiar phase structure in the model. At weak string coupling the theory reduces exactly to the trivial flat connection sector with instanton contributions exponentially suppressed, and the topological string partition function on the resolved conifold is reproduced in this regime. At a certain critical point all non-trivial vacua contribute, instantons are enhanced and the theory appears to undergo a phase transition into a strong coupling regime. We rederive these results by performing a saddle-point approximation to the exact partition function. We obtain a q-deformed version of the Douglas-Kazakov equation for two-dimensional Yang-Mills theory on the sphere, whose one-cut solution below the transition point reproduces the resolved conifold geometry. Above the critical point we propose a two-cut solution that should reproduce the chiral-antichiral dynamics found for black holes on the Calabi-Yau threefold and the Gross-Taylor string in the undeformed limit. The transition from the strong coupling phase to the weak coupling phase appears to be of third order.
Nakamura, Shin
2012-09-21
We find novel phase transitions and critical phenomena that occur only outside the linear-response regime of current-driven nonequilibrium states. We consider the strongly interacting (3+1)-dimensional N = 4 large-N(c) SU(N(c)) supersymmetric Yang-Mills theory with a single flavor of fundamental N = 2 hypermultiplet as a microscopic theory. We compute its nonlinear nonballistic quark-charge conductivity by using the AdS/CFT correspondence. We find that the system exhibits a novel nonequilibrium first-order phase transition where the conductivity jumps and the sign of the differential conductivity flips at finite current density. A nonequilibrium critical point is discovered at the end point of the first-order regime. We propose a nonequilibrium steady-state analogue of thermodynamic potential in terms of the gravity-dual theory in order to define the transition point. Nonequilibrium analogues of critical exponents are proposed as well. The critical behavior of the conductivity is numerically confirmed on the basis of these proposals. The present work provides a new example of nonequilibrium phase transitions and nonequilibrium critical points.
Energy Technology Data Exchange (ETDEWEB)
Vilkas, M J; Ishikawa, Y; Trabert, E
2007-03-27
Relativistic multireference many-body perturbation theory calculations have been performed on Xe{sup 43+}-Xe{sup 39+} ions, resulting in energy levels, electric dipole transition probabilities, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, frequency-dependent Breit correction and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.
Anand, Ankit; Roy, Nobhojit
2016-01-01
The Millennium Development Goals are now replaced by 17 sustainable development goals. The emphasis of old goals was on improving water, sanitation, and child mortality conditions in developing countries. The study explored the major question about the association between different household environment conditions with child survival and health in Sub-Saharan African and South Asian countries in the current scenario. This paper estimated the risk of death, morbidity, and undernutrition among children living in households with the improved sources of water, sanitation, and non-solid cooking fuel. Two sources of information are explored in this study. First, data from World Health Statistics (WHS)-2014 for all of the Sub-Saharan African and South Asian countries were used. Second, available standard Demographic and Health Survey (DHS) performed in the countries of Sub-Saharan Africa and South Asia after 2010 was included in the study. It resulted in the inclusion of 15 countries which were Bangladesh (2011), Congo Republic (2013-2014), Cote d'Ivoire (2011-2012), Ethiopia (2011), Gambia (2013), Mali (2012-2013), Mozambique (2011), Namibia (2013), Nepal (2011), Niger (2012), Nigeria (2013), Pakistan (2012-2013), Sierra Leone (2013), Uganda (2011), and Zambia (2013). The scatter plot diagram was plotted, and the curve was fitted using the WHS-2014. Cox regression and logistic regression were used to estimate adjusted risks (odds ratio) of child mortality and health outcomes using DHSs. The use of non-solid cooking fuel was very high in most of the Sub-Saharan African and South Asian countries. There was a positive correlation between improving access to safe drinking water and sanitation. The exponential curve fitted well with child mortality and household environmental indicators. The use of improved source of water and sanitation significantly related with the lower odds ratio of death, morbidity, and undernutrition among children aged 12-59 months. The risks were
Directory of Open Access Journals (Sweden)
Ankit eAnand
2016-05-01
Full Text Available The millennium development goals are now replaced by seventeen sustainable development goals. The emphasis of old goals was on improving water, sanitation, and child mortality conditions in developing countries. The study explored the major question about the association between different household environment conditions with child survival and health in Sub-Saharan African and South Asian countries in the current scenario. This paper estimated the risk of death, morbidity and under-nutrition among children living in households with the improved sources of water, sanitation and non-solid cooking fuel. Two sources of information explored in this study. First, data from World Health Statistics (WHS -2014 for all of the Sub-Saharan African and South Asian countries were used. Second, available standard Demographic and Health Survey performed in the countries of Sub-Saharan Africa and South Asia after 2010, included in the study. It resulted in inclusion of 15 countries which were Bangladesh (2011, Congo Republic (2013-14, Cote d'Ivoire (2011-12, Ethiopia (2011, Gambia (2013, Mali (2012-13, Mozambique (2011, Namibia (2013, Nepal (2011, Niger (2012, Nigeria (2013, Pakistan (2012-13, Sierra Leone (2013, Uganda (2011 and Zambia (2013. The Scatter plot diagram was plotted, and the curve was fitted using the WHS-2014. Cox regression and logistic regression were used to estimate adjusted risks (odds ratio of child mortality and health outcomes using DHS surveys. The use of non-solid cooking fuel was very high in most of the Sub-Saharan African and South Asian Countries. There was a positive correlation between improving access to safe drinking water and sanitation. The exponential curve fitted well with child mortality and Household environmental indicators. The use of improved source of water and sanitation significantly related with the lower odds ratio of death, morbidity and under-nutrition among children aged 12-59 months. The risks were not
The Simplest Unified Growth Theory
DEFF Research Database (Denmark)
Strulik, Holger; Weisdorf, Jacob Louis
This paper provides a unified growth theory, i.e. a model that explains the very long-run economic and demographic development path of industrialized economies, stretching from the pre-industrial era to present-day and beyond. Making strict use of Malthus' (1798) so-called preventive check...... hypothesis - that fertility rates vary inversely with the price of food - the current study offers a new and straightforward explanation for the demographic transition and the break with the Malthusian era. The current framework lends support to existing unified growth theories and is well in tune...... with historical evidence about structural transformation...
Energy Technology Data Exchange (ETDEWEB)
Mallamace, Francesco [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Tartaglia, Piero [Dipartimento di Fisica, INFM and Statistical Mechanics and Complexity Center, Universita di Roma La Sapienza, I-00185 Rome (Italy); Chen W R [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Faraone, Antonio [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Chen, S H [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
2004-10-27
We report a set of viscoelastic measurements in concentrated aqueous solutions of a copolymer micellar system with short-range inter-micellar attractive interactions, a colloidal system characterized, in different regions of the composition-temperature phase diagram, by the existence of a percolation line (PT) and a kinetic glass transition (KGT). Both these transitions cause dramatic changes in the system viscoelasticity. Whereas the observed variations of the shear moduli at the PT are described in terms of percolation models, for the structural arrest at the KGT we investigate the frequency-dependent shear modulus behaviours by using a mode coupling theory (MCT) approach.
Revisiting the deconfinement phase transition in SU(4) Yang-Mills theory in 2+1 dimensions
Holland, Kieran; Wiese, Uwe-Jens
2008-01-01
In order to deepen our understanding of the nature of the deconfinement phase transition for various gauge groups, we investigate SU(4) Yang-Mills theory in 2+1 dimensions. We find that the transition is weakly first order. We perform extensive Monte Carlo simulations on lattices with temporal extent N_t = 3, 4 and 5, and spatial sizes up to N_s = 20 N_t. We observe coexistence of confined and deconfined phases at the critical temperature, and finite-size scaling shows consistency with first order exponents. The continuum extrapolation of the latent heat yields L_h/T_c^3=0.187(9).
Kontani, H.; Inoue, Y.; Saito, T.; Yamakawa, Y.; Onari, S.
2012-01-01
The main features in iron-based superconductors would be (i) the orthorhombic transition accompanied by remarkable softening of shear modulus, (ii) high-Tc superconductivity close to the orthorhombic phase, and (iii) nematic transition in the tetragonal phase. In this paper, we present a unified explanation for them, based on the orbital fluctuation theory, considering both the e-ph and the Coulomb interaction. It is found that a small e-ph coupling constant ($\\lambda ~ 0.2$) is enough to pro...
DEFF Research Database (Denmark)
Hansen, Ole Erik; Stærdahl, Jens; Søndergård, Bent
-technological systems, calling attention to how such governance structures emerge, stabilize and become dominant, which functions governance structures have to serve to become efficient, and how they can be made subject to deliberate and purposeful shaping and transition. Taking this approach, research in planning......The paper suggests that the challenge of sustainability demands a shift of the attention of environmental planning and policy to the transition of socio-technological systems. Deliberate planning for sustainability then becomes a question of addressing governance structures of socio...... and policymaking for sustainability has to work with issues of understanding how actors and networks configure, requirements to effective networks and metagovernance of governance networks. Research within innovation systems, transition management and technology systems combined with planning and experimental...
Complex Network Theory Applied to the Growth of Kuala Lumpur's Public Urban Rail Transit Network.
Directory of Open Access Journals (Sweden)
Rui Ding
Full Text Available Recently, the number of studies involving complex network applications in transportation has increased steadily as scholars from various fields analyze traffic networks. Nonetheless, research on rail network growth is relatively rare. This research examines the evolution of the Public Urban Rail Transit Networks of Kuala Lumpur (PURTNoKL based on complex network theory and covers both the topological structure of the rail system and future trends in network growth. In addition, network performance when facing different attack strategies is also assessed. Three topological network characteristics are considered: connections, clustering and centrality. In PURTNoKL, we found that the total number of nodes and edges exhibit a linear relationship and that the average degree stays within the interval [2.0488, 2.6774] with heavy-tailed distributions. The evolutionary process shows that the cumulative probability distribution (CPD of degree and the average shortest path length show good fit with exponential distribution and normal distribution, respectively. Moreover, PURTNoKL exhibits clear cluster characteristics; most of the nodes have a 2-core value, and the CPDs of the centrality's closeness and betweenness follow a normal distribution function and an exponential distribution, respectively. Finally, we discuss four different types of network growth styles and the line extension process, which reveal that the rail network's growth is likely based on the nodes with the biggest lengths of the shortest path and that network protection should emphasize those nodes with the largest degrees and the highest betweenness values. This research may enhance the networkability of the rail system and better shape the future growth of public rail networks.
Complex Network Theory Applied to the Growth of Kuala Lumpur's Public Urban Rail Transit Network.
Ding, Rui; Ujang, Norsidah; Hamid, Hussain Bin; Wu, Jianjun
2015-01-01
Recently, the number of studies involving complex network applications in transportation has increased steadily as scholars from various fields analyze traffic networks. Nonetheless, research on rail network growth is relatively rare. This research examines the evolution of the Public Urban Rail Transit Networks of Kuala Lumpur (PURTNoKL) based on complex network theory and covers both the topological structure of the rail system and future trends in network growth. In addition, network performance when facing different attack strategies is also assessed. Three topological network characteristics are considered: connections, clustering and centrality. In PURTNoKL, we found that the total number of nodes and edges exhibit a linear relationship and that the average degree stays within the interval [2.0488, 2.6774] with heavy-tailed distributions. The evolutionary process shows that the cumulative probability distribution (CPD) of degree and the average shortest path length show good fit with exponential distribution and normal distribution, respectively. Moreover, PURTNoKL exhibits clear cluster characteristics; most of the nodes have a 2-core value, and the CPDs of the centrality's closeness and betweenness follow a normal distribution function and an exponential distribution, respectively. Finally, we discuss four different types of network growth styles and the line extension process, which reveal that the rail network's growth is likely based on the nodes with the biggest lengths of the shortest path and that network protection should emphasize those nodes with the largest degrees and the highest betweenness values. This research may enhance the networkability of the rail system and better shape the future growth of public rail networks.
Aquilanti, Vincenzo; Coutinho, Nayara Dantas; Carvalho-Silva, Valter Henrique
2017-03-01
This article surveys the empirical information which originated both by laboratory experiments and by computational simulations, and expands previous understanding of the rates of chemical processes in the low-temperature range, where deviations from linearity of Arrhenius plots were revealed. The phenomenological two-parameter Arrhenius equation requires improvement for applications where interpolation or extrapolations are demanded in various areas of modern science. Based on Tolman's theorem, the dependence of the reciprocal of the apparent activation energy as a function of reciprocal absolute temperature permits the introduction of a deviation parameter d covering uniformly a variety of rate processes, from those where quantum mechanical tunnelling is significant and d 0, corresponding to the Pareto-Tsallis statistical weights: these generalize the Boltzmann-Gibbs weight, which is recovered for d = 0. It is shown here how the weights arise, relaxing the thermodynamic equilibrium limit, either for a binomial distribution if d > 0 or for a negative binomial distribution if d kinetics, where transport phenomena accelerate processes as the temperature increases; (ii) the sub-Arrhenius kinetics, where quantum mechanical tunnelling propitiates low-temperature reactivity; (iii) the anti-Arrhenius kinetics, where processes with no energetic obstacles are rate-limited by molecular reorientation requirements. Particular attention is given for case (i) to the treatment of diffusion and viscosity, for case (ii) to formulation of a transition rate theory for chemical kinetics including quantum mechanical tunnelling, and for case (iii) to the stereodirectional specificity of the dynamics of reactions strongly hindered by the increase of temperature. This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'.
Statistical theory and transition in multiple-scale-lengths turbulence in plasmas
Energy Technology Data Exchange (ETDEWEB)
Itoh, Sanae-I. [Research Institute for Applied Mechanics, Kyushu Univ., Kasuga, Fukuoka (Japan); Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan)
2001-06-01
The statistical theory of strong turbulence in inhomogeneous plasmas is developed for the cases where fluctuations with different scale-lengths coexist. Nonlinear interactions in the same kind of fluctuations as well as nonlinear interplay between different classes of fluctuations are kept in the analysis. Nonlinear interactions are modelled as turbulent drag, nonlinear noise and nonlinear drive, and a set of Langevin equations is formulated. With the help of an Ansatz of a large number of degrees of freedom with positive Lyapunov number, Langevin equations are solved and the fluctuation dissipation theorem in the presence of strong plasma turbulence has been derived. A case where two driving mechanisms (one for micro mode and the other for semi-micro mode) coexist is investigated. It is found that there are several states of fluctuations: in one state, the micro mode is excited and the semi-micro mode is quenched; in the other state, the semi-micro mode is excited, and the micro mode remains at finite but suppressed level. New type of turbulence transition is obtained, and a cusp type catastrophe is revealed. A phase diagram is drawn for turbulence which is composed of multiple classes of fluctuations. Influence of the inhomogeneous global radial electric field is discussed. A new insight is given for the physics of internal transport barrier. Finally, the nonlocal heat transport due to the long-wave-length fluctuations, which are noise-pumped by shorter-wave-length ones, is analyzed and the impact on transient transport problems is discussed. (author)
Statistical theory and transition in multiple-scale-length turbulence in plasmas
Energy Technology Data Exchange (ETDEWEB)
Itoh, Sanae-I [Research Institute for Applied Mechanics, Kyushu University, Kasuga (Japan); Itoh, Kimitaka [National Institute for Fusion Science, Toki (Japan)
2001-08-01
The statistical theory of strong turbulence in inhomogeneous plasmas is developed for the cases where fluctuations with different scale lengths coexist. Nonlinear interactions in the same kind of fluctuations as well as nonlinear interplay between different classes of fluctuations are kept in the analysis. Nonlinear interactions are modelled as turbulent drag, nonlinear noise and nonlinear drive, and a set of Langevin equations is formulated. With the help of an Ansatz of a large number of degrees of freedom with positive Lyapunov number, Langevin equations are solved and the fluctuation dissipation theorem in the presence of strong plasma turbulence has been derived. A case where two driving mechanisms (one for the micro mode and the other for semi-micro mode) coexist is investigated. It is found that there are several states of fluctuations: in one state, the micro mode is excited and the semi-micro mode is quenched; in the other state, the semi-micro mode is excited, and the micro mode remains at finite but at a suppressed level. A new type of turbulence transition is obtained, and a cusp-type catastrophe is revealed. A phase diagram is drawn for turbulence which is composed of multiple classes of fluctuations. The influence of the inhomogeneous global radial electric field is discussed. A new insight is given for the physics of the internal transport barrier. Finally, the non-local heat transport due to the long-wavelength fluctuations, which are noise-pumped by shorter-wavelength fluctuations, is analysed and its impact on transient transport problems is discussed. (author)
Transitions in Theory and Practice: Managing Metals in the Circular Economy
Directory of Open Access Journals (Sweden)
Melissa Jackson
2014-07-01
Full Text Available Transitioning from current resource management practice dominated by linear economic models of consumption and production, to circular models of resource use, will require insights into the stages and processes associated with socio-technical transitions. This paper is concerned with transitions in practice. It explores two frameworks within the transitions literature—the multi-level perspective and transition management theory—for practical guidance to inform a deliberate transition in practice. The critical futures literature is proposed as a source of tools and methods to be used in conjunction with the transition frameworks to influence and enable transitions in practice. This enhanced practical guidance for initiating action is applied to a specific context—transitioning the Australian metals sector towards a circular economy model. This particular transition case study is relevant because the vision of a circular economy model of resource management is gaining traction internationally, Australia is significant globally as a supplier of finite mineral resources and it will also be used in a collaborative research project on Wealth from Waste to investigate possibilities for the circular economy and metals recycling.
Mross, David F; Senthil, T
2012-06-29
We construct a theory of continuous stripe melting quantum phase transitions in two-dimensional metals and the associated Fermi surface reconstruction. Such phase transitions are strongly coupled but yet theoretically tractable in situations where the stripe ordering is destroyed by proliferating doubled dislocations of the charge stripe order. The resulting non-Landau quantum critical point has strong stripe fluctuations which we show decouple dynamically from the Fermi surface even though static stripe ordering reconstructs the Fermi surface. We discuss connections to various stripe phenomena in the cuprates. We point out several puzzling aspects of old experimental results [G. Aeppli et al., Science 278, 1432 (1997)] on singular stripe fluctuations in the cuprates, and provide a possible explanation within our theory. These results may thus have been the first observation of non-Landau quantum criticality in an experiment.
Pietrow, M
2016-01-01
Considerable similarity between positronium atom and an exciton in a quantum dot is indicated. Following this, we apply the calculation regime from the theory of excitons to describe some aspects of formation of a positronium in matter. We consider the possibility of photonic deexcitation during Ps formation and show the way of calculation of its probability. The photonic transitions speculated here, if detected, allows improving experimental studies of solid matter with positron techniques.
Does the recent evolution of Canadian mortality agree with the epidemiologic transition theory?
Directory of Open Access Journals (Sweden)
Robert ChoiniÃƒÂ¨re
2008-06-01
Full Text Available After studying the epidemiologic transition's situation in Canada, it is determined that the delimitation of temporal stages within the epidemiologic transition as put forward by Omran (1971, 1998, Olshansky and Ault (1986, Rogers and Hackenberg (1987 and Olshansky et al. (1998 does not suit the Canadian evolution. Many of the researchers' postulates on the epidemiologic transition were not confirmed, which leads us to assert that, since 1958, the epidemiologic transition is best described as an evolution process rather than specific stages confined within time limits.
Discussion Forum--Population Theories: Their Implications on Population Education.
Population Education in Asia and the Pacific Newsletter, 1983
1983-01-01
Contends that unless population education programs have a clear conceptual framework built upon a consistent set of population theories, they will remain merely as appendices to established school projects. Several population theories and their implications for population education are described. These include Malthusian demographic transition,…
Pérez, E A Coello
2015-01-01
We present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant non-minimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoretical uncertainties at leading order. In order to probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. We also...
Tjipto-Margo, Broto; Evans, Glenn T.
1990-09-01
In the Onsager theory for the phase transition from the isotropic fluid to the nematic liquid crystal phase, the Helmholtz free energy of a fluid of hard convex bodies (HCBs) is expressed as the sum of an entropy of a mixing-like term and an energy-like term (from the interaction of the HCBs). Whereas the Onsager theory expresses the interaction term in a virial expansion and determines the consequences of B2 alone, here we extend that treatment to incorporate B3 (with its attendant dependence on the mutual orientation of three HCBs). For HCBs (and specifically for D∞h ellipsoids) with large aspect ratios (5:1 or greater), the incorporation of B2 and B3 suffices to predict the variation of the order parameter with density in accord with the Monte Carlo (MC) results of Allen and Wilson. As the aspect ratio decreases (from 5:1) to more spherical molecules (say 3:1), virial coefficients of higher order than B3 contribute to the interaction term and their effect is represented in part by the y-expansion (or resummation) theory proposed by Barboy and Gelbart. In this y-expansion-third virial-Onsager theory, the predicted transition densities are in accord with the MC values of Frenkel and Mulder for prolate ellipsoids. Neither the y expansion nor the direct B2 and B3 theories find the phase diagram (i.e., transition density and order parameter regarded as a function of aspect ratio) to be symmetric for prolate and oblate ellipsoids. The dependence of B3 on the mutual orientation of the ellipsoids is also discussed and previous work is also addressed.
THEORY OF THE THRESHOLD FIELD FOR THE DEPINNING TRANSITION OF A CHARGE-DENSITY WAVE
PIETRONERO, L; VERSTEEG, M
1991-01-01
The Hamiltonian of an elastic string pinned by random potentials is often used to describe the depinning transition of a charge density wave in the presence of impurity pinning. The properties of the pinned states show close analogies to those of glassy systems, while the depinning transition resemb
A two-loop study of the deconfinement transition in Yang-Mills theories: SU(3) and beyond
Reinosa, U; Tissier, M; Wschebor, N
2015-01-01
We study the confinement-deconfinement phase transition of pure Yang-Mills theories at finite temperature within a simple massive extension of standard background field methods. We generalize our recent next-to-leading-order perturbative calculation of the Polyakov loop and the related background field effective potential for the SU(2) theory to any compact and connex Lie group with a simple Lie algebra. We discuss in detail the SU(3) theory, where the two-loop corrections yield improved values for the first order transition temperature as compared to the one-loop result. We show that certain one-loop artifacts of thermodynamical observables disappear at two-loop order, as was already the case for the SU(2) theory. In particular, the entropy and the pressure are positive for all temperatures. We also discuss the groups SU(4) and Sp(2) which shed interesting light, respectively, on the relation between the (de)confinement of static matter sources in the various representations of the gauge group and on the use...
Evolutionary shaping of demographic schedules
Wachter, Kenneth W.; Steinsaltz, David; Evans, Steven N.
2014-01-01
Evolutionary processes of natural selection may be expected to leave their mark on age patterns of survival and reproduction. Demographic theory includes three main strands—mutation accumulation, stochastic vitality, and optimal life histories. This paper reviews the three strands and, concentrating on mutation accumulation, extends a mathematical result with broad implications concerning the effect of interactions between small age-specific effects of deleterious mutant alleles. Empirical data from genomic sequencing along with prospects for combining strands of theory hold hope for future progress. PMID:25024186
SU(N) transitions in M-theory on Calabi-Yau fourfolds and background fluxes
Jockers, Hans; Morrison, David R; Plesser, M Ronen
2016-01-01
We study M-theory on a Calabi-Yau fourfold with a smooth surface $S$ of $A_{N-1}$ singularities. The resulting three-dimensional theory has a $\\mathcal{N}=2$ $SU(N)$ gauge theory sector, which we obtain from a twisted dimensional reduction of a seven-dimensional $\\mathcal{N}=1$ $SU(N)$ gauge theory on the surface $S$. A variant of the Vafa-Witten equations governs the moduli space of the gauge theory, which, for a trivial $SU(N)$ principal bundle over $S$, admits a Coulomb and a Higgs branch. In M-theory these two gauge theory branches arise from a resolution and a deformation to smooth Calabi-Yau fourfolds, respectively. We find that the deformed Calabi-Yau fourfold associated to the Higgs branch requires for consistency a non-trivial four-form background flux in M-theory. The flat directions of the flux-induced superpotential are in agreement with the gauge theory prediction for the moduli space of the Higgs branch. We illustrate our findings with explicit examples that realize the Coulomb and Higgs phase t...
Klippenstein, S J; Harding, L B; Ruscic, B; Sivaramakrishnan, R; Srinivasan, N K; Su, M-C; Michael, J V
2009-09-24
Primary and secondary reactions involved in the thermal decomposition of NH2OH are studied with a combination of shock tube experiments and transition state theory based theoretical kinetics. This coupled theory and experiment study demonstrates the utility of NH2OH as a high temperature source of OH radicals. The reflected shock technique is employed in the determination of OH radical time profiles via multipass electronic absorption spectrometry. O-atoms are searched for with atomic resonance absorption spectrometry. The experiments provide a direct measurement of the rate coefficient, k1, for the thermal decomposition of NH2OH. Secondary rate measurements are obtained for the NH2 + OH (5a) and NH2OH + OH (6a) abstraction reactions. The experimental data are obtained for temperatures in the range from 1355 to 1889 K and are well represented by the respective rate expressions: log[k/(cm3 molecule(-1) s(-1))] = (-10.12 +/- 0.20) + (-6793 +/- 317 K/T) (k1); log[k/(cm3 molecule(-1) s(-1))] = (-10.00 +/- 0.06) + (-879 +/- 101 K/T) (k5a); log[k/(cm3 molecule(-1) s(-1))] = (-9.75 +/- 0.08) + (-1248 +/- 123 K/T) (k6a). Theoretical predictions are made for these rate coefficients as well for the reactions of NH2OH + NH2, NH2OH + NH, NH + OH, NH2 + NH2, NH2 + NH, and NH + NH, each of which could be of secondary importance in NH2OH thermal decomposition. The theoretical analyses employ a combination of ab initio transition state theory and master equation simulations. Comparisons between theory and experiment are made where possible. Modest adjustments of predicted barrier heights (i.e., by 2 kcal/mol or less) generally yield good agreement between theory and experiment. The rate coefficients obtained here should be of utility in modeling NOx in various combustion environments.
Quantized Brans-Dicke theory: Phase transition, strong coupling limit, and general relativity
Pal, Sridip
2016-10-01
We show that Friedmann-Robertson-Walker geometry with a flat spatial section in quantized (Wheeler deWitt quantization) Brans-Dicke (BD) theory reveals a rich phase structure owing to anomalous breaking of a classical symmetry, which maps the scale factor a ↦λ a for some constant λ . In the weak coupling (ω ) limit, the theory goes from a symmetry preserving phase to a broken phase. The existence of a phase boundary is an obstruction to another classical symmetry [see V. Faraoni, Phys. Rev. D 59, 084021 (1999).] (which relates two BD theories with different couplings) admitted by BD theory with scale invariant matter content, i.e., Tμμ=0 . Classically, this prohibits the BD theory from reducing to general relativity (GR) for scale invariant matter content. We show that a strong coupling limit of both BD and GR preserves the symmetry involving the scale factor. We also show that with scale invariant matter content (radiation, i.e., P =1/3 ρ ), the quantized BD theory does reduce to GR as ω →∞ , which is in sharp contrast to classical behavior. This is a first known illustration of a scenario where quantized BD theory provides an example of anomalous symmetry breaking and resulting binary phase structure. We make a conjecture regarding the strong coupling limit of the BD theory in a generic scenario.
The Economic Foundations of Demographic Transition
Rodrigo Cerda
2002-01-01
The paper develops a general equilibrium model where population sources, such as fertility and mortality rates, are chosen variables. It is shown that the evolution of population over time depends on income and relative prices of mortality and fertility rates. Initially as a country develops, countries should face a period with increasing fertility and higher population growth rates but later fertility and population growth rate should decrease as their relative prices increase. It is also sh...
Product Variety and the Demographic Transition
DEFF Research Database (Denmark)
Guzmán, Ricardo Andrés; Weisdorf, Jacob Louis
Why does the rate of population growth decline in the face of economic growth? We show that growing product variety may induce a permanent reduction in the demand for children and a continuous rise in income and consumption.......Why does the rate of population growth decline in the face of economic growth? We show that growing product variety may induce a permanent reduction in the demand for children and a continuous rise in income and consumption....
Product variety and the demographic transition
DEFF Research Database (Denmark)
Guzmán, Ricardo Andrés; Weisdorf, Jacob Louis
2010-01-01
Why does the rate of population growth decline in the face of economic growth? We show that growing product variety may induce a permanent reduction in the demand for children and a continuous rise in income and consumption....
Product Variety and the Demographic Transition
DEFF Research Database (Denmark)
Guzmán, Ricardo Andrés; Weisdorf, Jacob Louis
Why does the rate of population growth decline in the face of economic growth? We show that growing product variety may induce a permanent reduction in the demand for children and a continuous rise in income and consumption....
Misra, D.; Kundu, T. K.
2016-09-01
Density functional theory with appropriate functional has been employed to investigate the metal to insulator transition in oxygen deficient LaNiO3-x (x = 0.0, 0.25, 0.5, 1.0) compounds. While the metallic nature of LaNiO3 is characterized by the low temperature Fermi liquid behavior of resistivity and a finite density of states at the Fermi level, the density of states and the transport properties clearly identify LaNiO2.75 as a semiconductor, and LaNiO2.5 as an insulator, which is followed by another insulator to semiconductor transition with further increase of x to ‘1’ in LaNiO2. This oxygen vacancy controlled metal to insulator transition is explained on the basis of non-adiabatic polaronic transport. From the covalency metric calculation of the chemical bonding and the Bader charge transfer analysis, this metal to insulator transition is attributed to the enhanced covalent part in the chemical bonding and reduced charge transfer from Ni to O atoms in LaNiO3-x compounds.
Institute of Scientific and Technical Information of China (English)
郭剑雄
2016-01-01
传统农业、工业化农业和现代农业分别存在马尔萨斯稳态、索洛稳态和现代持续增长稳态三种不同的产出增长结构。传统农业经由工业化农业向现代农业的发展，亦即马尔萨斯稳态经索洛稳态向现代持续增长稳态的渐进过渡。离开工业化的外部冲击，难以设想突破传统农业低技术均衡的前一种过渡；而人口生产转型则是工业化农业成长为现代农业的内生动力。当前中国农业发展政策调节的基本目标，仍是通过劳动力转移继续完成马尔萨斯稳态向索洛稳态的过渡，同时应前瞻性地为人力资本引入农业生产创设条件。%Malthus steady state,Solow steady state and modern sustainable growth steady state respec-tively exist in traditional agriculture,industrial agriculture and modern agriculture.The process tradi-tional agriculture developing into modern agriculture by industrial agriculture is a gradual transition from Malthus steady state to modern sustainable growth steady state by Solow steady state.It is hard to imagine a breakthrough in low technology balance of traditional agricultural without the external shock of industrialization.While the demographic transition is the endogenous dynamic from industrial agriculture to modern agriculture,at present,the basic aim of China�s agricultural development policy is still to complete the transition from Malthus steady state to Solow steady state by labor transfer, and create conditions for introducing human capital into agricultural production.
Ribas, Marlos O
2009-01-01
In this work the accelerated-decelerated transition in a primordial Universe is investigated by using the dynamics of fermion fields within the context of Einstein-Cartan theory, where apart from the curvature the space-time is also described by a torsion field. The model analyzed here has only a fermion field as the source of the gravitational field. The term associated with the spin of the fermion field plays the role of the inflaton which contributes to an accelerated regime whereas the one related to the fermion mass behaves as a matter field and is the responsible for a decelerated regime. Hence, by taking into account the spin of a massive fermion field it is possible to characterize the transition from the accelerated to the decelerated periods of the primordial Universe.
Advances in Unsteady Boundary Layer Transition Research, Part I: Theory and Modeling
Directory of Open Access Journals (Sweden)
M. T. Schobeiri
2003-01-01
Full Text Available This two-part article presents recent advances in boundary layer research that deal with the unsteady boundary layer transition modeling and its validation. A new unsteady boundary layer transition model was developed based on a universal unsteady intermittency function. It accounts for the effects of periodic unsteady wake flow on the boundary layer transition. To establish the transition model, an inductive approach was implemented; the approach was based on the results of comprehensive experimental and theoretical studies of unsteady wake flow and unsteady boundary layer flow. The experiments were performed on a curved plate at a zero streamwise pressure gradient under a periodic unsteady wake flow, where the frequency of the periodic unsteady flow was varied. To validate the model, systematic experimental investigations were performed on the suction and pressure surfaces of turbine blades integrated into a high-subsonic cascade test facility, which was designed for unsteady boundary layer investigations. The analysis of the experiment's results and comparison with the model's prediction confirm the validity of the model and its ability to predict accurately the unsteady boundary layer transition.
Institute of Scientific and Technical Information of China (English)
LIU Yan-Hui; TIAN Fu-Bo; MA Yan-Ming; HE Zhi; CUI Tian; LIU Bing-Bing; ZOU Guang-Tian
2008-01-01
Crystal structures and optical properties of the δ-O,2 phase and the ε-O,8 phase have been investigated by using the ab initio pseudopotential plane-wave method. It is found that the phase transition is of the first order with a discontinuous volumetric change from the antiferromagnetic δ-O,2 phase to the nonmagnetic ε-O8 phase, consistent with the experimental findings. The energy band calculations show that the direct band gap changes into an indirect band gap after the phase transition. The apparent change in the optical properties can be used for identifying the phase transition from δ-O2 to ε-O,8.
Electric Transition Dipole Moment in pre-Born-Oppenheimer Molecular Structure Theory
Simmen, Benjamin; Reiher, Markus
2014-01-01
This paper presents the calculation of the electric transition dipole moment in a pre-Born-Oppenheimer framework. Electrons and nuclei are treated equally in terms of the parametrization of the non-relativistic total wave function, which is written as a linear combination of basis functions constructed with explicitly correlated Gaussian functions and the global vector representation. The integrals of the electric transition dipole moment are derived corresponding to these basis functions in both the length and the velocity representation. The complete derivation and the calculations are performed in laboratory-fixed Cartesian coordinates without relying on coordinates which separate the center of mass from the translationally invariant degrees of freedom. The effect of the overall motion is eliminated via translationally invariant integral expressions. As a numerical example the electric transition dipole moment is calculated between two rovibronic levels of the H2 molecule assignable to the lowest rovibrati...
Geometry of dynamics and phase transitions in classical lattice $\\phi^{4}$ theories
Caiani, L; Clementi, C; Pettini, G; Pettini, M; Gatto, R; Caiani, Lando; Casetti, Lapo; Clementi, Cecilia; Pettini, Giulio; Pettini, Marco; Gatto, Raoul
1998-01-01
We perform a microcanonical study of classical lattice phi^4 field models in 3 dimensions with O(n) symmetries. The Hamiltonian flows associated to these systems that undergo a second order phase transition in the thermodynamic limit are here investigated. The microscopic Hamiltonian dynamics neatly reveals the presence of a phase transition through the time averages of conventional thermodynamical observables. Moreover, peculiar behaviors of the largest Lyapunov exponents at the transition point are observed. A Riemannian geometrization of Hamiltonian dynamics is then used to introduce other relevant observables, that are measured as functions of both energy density and temperature. On the basis of a simple and abstract geometric model, we suggest that the apparently singular behaviour of these geometric observables might probe a major topological change of the manifolds whose geodesics are the natural motions.
A theory of lead-time in probabilistic excitation of L/H transition
Energy Technology Data Exchange (ETDEWEB)
Toda, Shinichiro; Itoh, Sanae-I.; Yagi, Masatoshi [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Itoh, Kimitaka [National Inst. for Fusion Science, Toki, Gifu (Japan); Fukuyama, Atsushi [Kyoto Univ. (Japan). Dept. of Nuclear Engineering
2000-07-01
A quantity of a lead-time, t{sub lead}, is newly introduced to examine the probabilistic occurrence of the L/H transition. The lead-time is a time period during which a transition is likely to occur. We show that the lead-time has the statistical distribution as a function of the distance from critical parameter, e.g.|n{sub c} - n{sub c0}|when the density is a key parameter for transition. It has the dependence like t{sub lead} {proportional_to}|n{sub c} - n{sub c0}|{sup 2} if the background noise distribution is given as P (n{sub c}) {proportional_to}|n{sub c} - n{sub c0}|{sup -2}. (author)
Directory of Open Access Journals (Sweden)
Philippe Bocquier
2005-05-01
Full Text Available This paper proposes to critically examine the United Nations projections on urbanisation. Both the estimates of current trends based on national data and the method of projection are evaluated. The theory of mobility transition is used as an alternative hypothesis. Projections are proposed using a polynomial model and compared to the UN projections, which are based on a linear model. The conclusion is that UN projections may overestimate the urban population for the year 2030 by almost one billion, or 19% in relative term. The overestimation would be particularly more pronounced for developing countries and may exceed 30% in Africa, India and Oceania.
Theory on single molecule_photon cryocooler—— Conception and quantum transition processes
Institute of Scientific and Technical Information of China (English)
秦伟平; 陈宝玖; 秦冠仕; 杜国同; 许武; 黄世华
2001-01-01
The micro mechanism of anti_Stokes fluorescent cooling was investigated on molecular or ionic scale. A new conception of single molecule_photon cryocooler (SMPC) was given, and the smallest cryocooler in the world was predicted. We described SMPC and its running principle in detail. The quantum transition processes of SMPC and the largest cooling coefficient that SMPC can get in an optical transition were given. Also we studied the random property of SMPC in cooling processes. The thermodynamic behavior of single Yb3+ ion as a photon cryocooler was imitated.
Blackwell, Lisa S; Trzesniewski, Kali H; Dweck, Carol Sorich
2007-01-01
Two studies explored the role of implicit theories of intelligence in adolescents' mathematics achievement. In Study 1 with 373 7th graders, the belief that intelligence is malleable (incremental theory) predicted an upward trajectory in grades over the two years of junior high school, while a belief that intelligence is fixed (entity theory) predicted a flat trajectory. A mediational model including learning goals, positive beliefs about effort, and causal attributions and strategies was tested. In Study 2, an intervention teaching an incremental theory to 7th graders (N=48) promoted positive change in classroom motivation, compared with a control group (N=43). Simultaneously, students in the control group displayed a continuing downward trajectory in grades, while this decline was reversed for students in the experimental group.
Kunkel, Christian; Viñes, Francesc; Lourenço, Mirtha A. O.; Ferreira, Paula; Gomes, José R. B.; Illas, Francesc
2017-03-01
Efficient separation of CO2/CH4 is critical in biogas upgrading, requiring highly selective adsorbents. Based on the adsorption energies of -0.30 and -0.14 eV, previously calculated by dispersion corrected density functional theory for adsorption/desorption of CO2 and CH4 on the functionalized periodic mesoporous phenylene-silica material APTMS@Ph-PMO, respectively, transition state theory rates were derived and used to simulate the adsorption/desorption rates of these two gases on APTMS@Ph-PMO. The latter yielded an estimation of initial CO2/CH4 selectivity at various temperatures. At T = 298 K, selectivity of 32.2 agrees to an experimental value of 26.1, which validates the method used for evaluating CO2/CH4 adsorption selectivities.
Abrahams, Elihu; Wölfle, Peter
2012-02-28
We use the recently developed critical quasiparticle theory to derive the scaling behavior associated with a quantum critical point in a correlated metal. This is applied to the magnetic-field induced quantum critical point observed in YbRh(2)Si(2), for which we also derive the critical behavior of the specific heat, resistivity, thermopower, magnetization and susceptibility, the Grüneisen coefficient, and the thermal expansion coefficient. The theory accounts very well for the available experimental results.
Phase transitions in higher derivative gravity and gauge theory: R-charged black holes
Dey, Tanay K.; Mukherji, Sudipta; Mukhopadhyay, Subir; Sarkar, Swarnendu
2007-09-01
This is a continuation of our earlier work where we constructed a phenomenologically motivated effective action of the boundary gauge theory at finite temperature and finite gauge coupling on S3 × S1. In this paper, we argue that this effective action qualitatively reproduces the gauge theory representing various bulk phases of R-charged black hole with Gauss-Bonnet correction. We analyze the system both in canonical and grand canonical ensemble.
Phase transitions in higher derivative gravity and gauge theory: R-charged black holes
Dey, Tanay K; Mukhopadhyay, Subir; Sarkar, Swarnendu
2007-01-01
This is a continuation of our earlier work where we constructed a phenomenologically motivated effective action of the boundary gauge theory at finite temperature and finite gauge coupling on $S^3 \\times S^1$. In this paper, we argue that this effective action qualitatively reproduces the gauge theory representing various bulk phases of R-charged black hole with Gauss-Bonnet correction. We analyze the system both in canonical and grand canonical ensemble.
Alpha-helix <-> random coil phase transition: analysis of ab initio theory predictions
DEFF Research Database (Denmark)
Solov'yov, Ilia; Yakubovich, Alexander V.; Solov'yov, Andrey V.;
2008-01-01
In the present paper we present results of calculations obtained with the use of the theoretical method described in our preceding paper [Eur. Phys. J. D, DOI 10.1140/epjd/e2007-00328-9] and perform detail analysis of -helix random coil transition in alanine polypeptides of different length. We...
The Rise of Obesity in Transition: Theory and Empirical Evidence from Russia
Huffman, S.K.; Rizov, M.I.
2010-01-01
This paper integrates theoretical and empirical models to study the rise of human obesity in Russia during the transition from a planned to a market economy. To test our hypotheses we use recent individual-level data from the Russian Longitudinal Monitoring Survey for 1995 and 2004 capturing represe
The evolution of bank credit quality in transition : theory and evidence from Romania
Perotti, E.C.; Carare, O.
1996-01-01
The paper develops a simple theoretical framework of financial discipline during the stabilization of a transition economy, from which it derives an empirical measure to assess whether the banking sector has started to act as a source of financial discipline, or just as a temporary buffer for enterp
DEFF Research Database (Denmark)
Lindgård, Per-Anker; Mouritsen, Ole G.
1990-01-01
-dimensional Monte Carlo simulation, showing clear precursor phenomena near the first-order transition and spontaneous nucleation. The kinetics of the domain growth is studied and found to be exceedingly slow. The results are applicable for martensitic transformations and structural surface...
The Case for a Dual-Process Theory of Transitive Reasoning
Wright, Barlow C.
2012-01-01
Ever since its popularisation by Piaget around 60 years ago, transitive reasoning (deductively-inferring A greater than C from premises A greater than B and B greater than C) has been of psychological interest both as a mental phenomenon and as a tool in areas of psychological discourse. However, the focus of interest in it has shifted…
Ricca, Alessandra; Bauschlicher, Charles W.; Langhoff, Stephen R. (Technical Monitor)
1994-01-01
Density functional theory (DFT) is found to give a better description of the geometries and vibrational frequencies of FeL and FeL(sup +) systems than second order Moller Plesset perturbation theory (MP2). Namely, the DFT correctly predicts the shift in the CO vibrational frequency between free CO and the Sigma(sup -) state of FeCO and yields a good result for the Fe-C distance in the quartet states of FeCH4(+) 4 These are properties where the MP2 results are unsatisfactory. Thus DFT appears to be an excellent approach for optimizing the geometries and computing the zero-point energies of systems containing first transition row atoms. Because the DFT approach is biased in favor of the 3d(exp 7) occupation, whereas the more traditional approaches are biased in favor of the 3d(exp 6) occupation, differences are found in the relative ordering of states. It is shown that if the dissociation is computed to the most appropriate atomic asymptote and corrected to the ground state asymptote using the experimental separations, the DFT results are in good agreement with high levels of theory. The energetics at the DFT level are much superior to the MP2 and in most cases in good agreement with high levels of theory.
Introduction: evolutionary theory and the search for a unified theory of fertility.
Bock, John
2002-01-01
Demography and evolutionary biology share common origins but have divergent emphasis on the role of theory in understanding population phenomena. A unified theory of fertility would be beneficial in explaining variation in demographic characteristics across geographic and temporal gulfs and in integrating disparate perspectives. The six papers in this thematic collection represent a nascent but vital field: human evolutionary demography. These papers examine the ways in which evolutionary theory can inform, strengthen, and focus research on topics of long-standing interest to demographers by explicitly modeling the relationship of socioecological variables to life history traits. The papers demonstrate that an understanding of human life history evolution and the use of evolutionary theory as an organizing framework can lead to a productive reassessment of five areas, which are of long-standing concern to demographers, and which conventional demographic approaches have had limited success in understanding. These are conflicts of interest between parents and children and between men and women, the allocation of resources to competing and/or alternative forms of investment in reproduction and parenting, resource flow within the household, demographic transitions and particularly the fertility transition associated with economic development, and variation in life history characteristics such as fertility and mortality across populations. Future research integrating models of trait-environment correlation with models of individual information processing and decision-making will help identify areas of focus, revitalize current models, and play a leading role in the development of a unified theory of fertility applicable across societies and times.
Tretyakov, Nikita; Vollmer, Doris; Butt, Hans-Jürgen; Dünweg, Burkhard; Daoulas, Kostas Ch
2016-01-01
Classical density functional theory is applied to investigate the validity of a phenomenological force-balance description of the stability of the Cassie state of liquids on substrates with nanoscale corrugation. A bulk free-energy functional of third order in local density is combined with a square-gradient term, describing the liquid-vapor interface. The bulk free energy is parameterized to reproduce the liquid density and the compressibility of water. The square-gradient term is adjusted to model the width of the water-vapor interface. The substrate is modeled by an external potential, based upon Lennard-Jones interactions. The three-dimensional calculation focuses on substrates patterned with nanostripes and square-shaped nanopillars. Using both the force-balance relation and density-functional theory, we locate the Cassie-to-Wenzel transition as a function of the corrugation parameters. We demonstrate that the force-balance relation gives a qualitatively reasonable description of the transition even on t...
Transition operators in electromagnetic-wave diffraction theory. II - Applications to optics
Hahne, G. E.
1993-01-01
The theory developed by Hahne (1992) for the diffraction of time-harmonic electromagnetic waves from fixed obstacles is briefly summarized and extended. Applications of the theory are considered which comprise, first, a spherical harmonic expansion of the so-called radiation impedance operator in the theory, for a spherical surface, and second, a reconsideration of familiar short-wavelength approximation from the new standpoint, including a derivation of the so-called physical optics method on the basis of quasi-planar approximation to the radiation impedance operator, augmented by the method of stationary phase. The latter includes a rederivation of the geometrical optics approximation for the complete Green's function for the electromagnetic field in the presence of a smooth- and a convex-surfaced perfectly electrically conductive obstacle.
The Mott transition in V 2O 3 and NiSe xS 2- x: insights from dynamical mean field theory
Kotliar, G.
1999-01-01
We discuss some aspects of the pressure (or interaction) driven Mott transition, in three-dimensional transition metal oxides by means of dynamical mean field theory. We isolate the universal properties of the transition from the aspects which depend more on the detailed chemistry of the compounds. In this light we can understand the main differences and the remarkable similarities between the NiSe xS 2- x and the V 2O 3 system. Both theory and experiment converge on the transfer of spectral weight from low energies to high energies as the universal mechanism underlying the Mott transition, and we comment on the possible relevance of these ideas to other metal to nonmetal transitions.
Lorquet, J. C.
2017-04-01
The atom-diatom interaction is studied by classical mechanics using Jacobi coordinates (R, r, θ). Reactivity criteria that go beyond the simple requirement of transition state theory (i.e., PR* > 0) are derived in terms of specific initial conditions. Trajectories that exactly fulfill these conditions cross the conventional dividing surface used in transition state theory (i.e., the plane in configuration space passing through a saddle point of the potential energy surface and perpendicular to the reaction coordinate) only once. Furthermore, they are observed to be strikingly similar and to form a tightly packed bundle of perfectly collimated trajectories in the two-dimensional (R, r) configuration space, although their angular motion is highly specific for each one. Particular attention is paid to symmetrical transition states (i.e., either collinear or T-shaped with C2v symmetry) for which decoupling between angular and radial coordinates is observed, as a result of selection rules that reduce to zero Coriolis couplings between modes that belong to different irreducible representations. Liapunov exponents are equal to zero and Hamilton's characteristic function is planar in that part of configuration space that is visited by reactive trajectories. Detailed consideration is given to the concept of average reactive trajectory, which starts right from the saddle point and which is shown to be free of curvature-induced Coriolis coupling. The reaction path Hamiltonian model, together with a symmetry-based separation of the angular degree of freedom, provides an appropriate framework that leads to the formulation of an effective two-dimensional Hamiltonian. The success of the adiabatic approximation in this model is due to the symmetry of the transition state, not to a separation of time scales. Adjacent trajectories, i.e., those that do not exactly fulfill the reactivity conditions have similar characteristics, but the quality of the approximation is lower. At higher
Kerner, Boris S; Klenov, Sergey L; Schreckenberg, Michael
2014-05-01
Physical features of induced phase transitions in a metastable free flow at an on-ramp bottleneck in three-phase and two-phase cellular automaton (CA) traffic-flow models have been revealed. It turns out that at given flow rates at the bottleneck, to induce a moving jam (F → J transition) in the metastable free flow through the application of a time-limited on-ramp inflow impulse, in both two-phase and three-phase CA models the same critical amplitude of the impulse is required. If a smaller impulse than this critical one is applied, neither F → J transition nor other phase transitions can occur in the two-phase CA model. We have found that in contrast with the two-phase CA model, in the three-phase CA model, if the same smaller impulse is applied, then a phase transition from free flow to synchronized flow (F → S transition) can be induced at the bottleneck. This explains why rather than the F → J transition, in the three-phase theory traffic breakdown at a highway bottleneck is governed by an F → S transition, as observed in real measured traffic data. None of two-phase traffic-flow theories incorporates an F → S transition in a metastable free flow at the bottleneck that is the main feature of the three-phase theory. On the one hand, this shows the incommensurability of three-phase and two-phase traffic-flow theories. On the other hand, this clarifies why none of the two-phase traffic-flow theories can explain the set of fundamental empirical features of traffic breakdown at highway bottlenecks.
The Earth expansion theory and its transition from scientific hypothesis to pseudoscientific belief
Sudiro, P.
2014-06-01
During the first half of 20th century, the dominant global tectonics model based on Earth contraction had increasing problems accommodating new geological evidence, with the result that alternative geodynamic theories were investigated. Due to the level of scientific knowledge and the limited amount of data available in many scientific disciplines at the time, not only was contractionism considered a valid scientific theory but the debate also included expansionism, mobilism on a fixed-dimension planet, or various combinations of these geodynamic hypotheses. Geologists and physicists generally accepted that planets could change their dimensions, although the change of volume was generally believed to happen because of a contraction, not an expansion. Constant generation of new matter in the universe was a possibility accepted by science, as it was the variation in the cosmological constants. Continental drift, instead, was a more heterodox theory, requiring a larger effort from the geoscientists to be accepted. The new geological data collected in the following decades, an improved knowledge of the physical processes, the increased resolution and penetration of geophysical tools, and the sensitivity of measurements in physics decreased the uncertainty level in many fields of science. Theorists now had less freedom for speculation because their theories had to accommodate more data, and more limiting conditions to respect. This explains the rapid replacement of contracting Earth, expanding Earth, and continental drift theories by plate tectonics once the symmetrical oceanic magnetic striping was discovered, because none of the previous models could explain and incorporate the new oceanographic and geophysical data. Expansionism could survive after the introduction of plate tectonics because its proponents have increasingly detached their theory from reality by systematically rejecting or overlooking any contrary evidence, and selectively picking only the data that
Grady, Michael
2011-01-01
SU(2) lattice gauge theory is extended to a larger coupling space where the coupling parameter for horizontal (spacelike) plaquettes, $\\beta_H$, differs from that for vertical (Euclidean timelike) plaquettes, $\\beta_V$. When $\\beta_H \\rightarrow \\infty$ the system, when in Coulomb Gauge, splits into multiple independent 3-d O(4) Heisenberg models on spacelike hyperlayers. Through consideration of the robustness of the Heisenberg model phase transition to small perturbations, and illustrated by Monte Carlo simulations, it is shown that the ferromagnetic phase transition in this model persists for $\\beta_H < \\infty$. Once it has entered the phase-plane it must continue to another edge due to its symmetry-breaking nature, and therefore must necessarily cross the $\\beta_V = \\beta_H$ line at a finite value. Indeed, a higher-order SU(2) phase transition is found at $\\beta = 3.18 \\pm 0.08$, from a finite-size scaling analysis of the Coulomb gauge magnetization from Monte Carlo simulations, which also yields criti...
Sung, Connie; Connor, Annemarie
2017-08-01
This study examined the utility of social-cognitive career theory (SCCT; Lent, Brown, & Hackett, 1994) as a framework to investigate career self-efficacy, outcome expectations, goals, and contextual supports and barriers as predictors of choice actions among transition-age individuals with epilepsy. Moreover, these SCCT constructs are offered as an operational definition of work participation in this population. Using a quantitative descriptive research design and hierarchical regression analysis (HRA), 90 transition-age individuals with epilepsy, age 18-25, were recruited from affiliates of the Epilepsy Foundation and invited to complete an online survey comprised of a series of self-report social-cognitive measures. The HRA findings indicated that self-efficacy, outcome expectations, and environmental supports were significant predictors of work participation in youth and young adults with epilepsy. The final model accounted for 58% of the variance in work participation, which is considered a large effect size. The research findings provide support for the use of the SCCT framework to identify predictors of work participation and to provide guidance for designing customized vocational rehabilitation services and career development interventions for individuals with epilepsy in the transition from adolescence to adulthood. (PsycINFO Database Record (c) 2017 APA, all rights reserved).
Theory of the anomalous critical behavior for the smectic-A -hexatic transition
Kats, E. I.; Lebedev, V. V.; Muratov, A. R.
2016-06-01
We propose a theoretical explanation for the long-standing problem of the anomalous critical behavior of the heat capacity near the smectic-A -hexatic phase transition. Experiments find a large specific heat critical exponent α =0.5 -0.7 , which is inconsistent with a small negative value α ≈-0.01 expected for the three-dimensional X Y universality class. We show that most of the observed features can be explained by treating simultaneously fluctuations of the hexatic orientational and translational (positional) order parameters. Assuming that the translational correlation length ξt r is much larger than the hexatic correlation length ξh, we calculate the temperature dependence of the heat capacity in the critical region near the smectic-A -hexatic phase transition. Our results are in quantitative agreement with the calorimetric experimental data.
Teodorescu, Razvan
2009-10-01
Systems of oscillators coupled non-linearly (stochastically or not) are ubiquitous in nature and can explain many complex phenomena: coupled Josephson junction arrays, cardiac pacemaker cells, swarms or flocks of insects and birds, etc. They are know to have a non-trivial phase diagram, which includes chaotic, partially synchronized, and fully synchronized phases. A traditional model for this class of problems is the Kuramoto system of oscillators, which has been studied extensively for the last three decades. The model is a canonical example for non-equilibrium, dynamical phase transitions, so little understood in physics. From a stochastic analysis point of view, the transition is described by the large deviations principle, which offers little information on the scaling behavior near the critical point. I will discuss a special case of the model, which allows a rigorous analysis of the critical properties of the model, and reveals a new, anomalous scaling behavior in the vicinity of the critical point.
Theory of the anomalous critical behavior for the smectic-A-hexatic transition.
Kats, E I; Lebedev, V V; Muratov, A R
2016-06-01
We propose a theoretical explanation for the long-standing problem of the anomalous critical behavior of the heat capacity near the smectic-A-hexatic phase transition. Experiments find a large specific heat critical exponent α=0.5-0.7, which is inconsistent with a small negative value α≈-0.01 expected for the three-dimensional XY universality class. We show that most of the observed features can be explained by treating simultaneously fluctuations of the hexatic orientational and translational (positional) order parameters. Assuming that the translational correlation length ξ_{tr} is much larger than the hexatic correlation length ξ_{h}, we calculate the temperature dependence of the heat capacity in the critical region near the smectic-A-hexatic phase transition. Our results are in quantitative agreement with the calorimetric experimental data.
Energy Technology Data Exchange (ETDEWEB)
Kolesnikov, R.A.; Krommes, J.A.
2005-09-22
The collisionless limit of the transition to ion-temperature-gradient-driven plasma turbulence is considered with a dynamical-systems approach. The importance of systematic analysis for understanding the differences in the bifurcations and dynamics of linearly damped and undamped systems is emphasized. A model with ten degrees of freedom is studied as a concrete example. A four-dimensional center manifold (CM) is analyzed, and fixed points of its dynamics are identified and used to predict a ''Dimits shift'' of the threshold for turbulence due to the excitation of zonal flows. The exact value of that shift in terms of physical parameters is established for the model; the effects of higher-order truncations on the dynamics are noted. Multiple-scale analysis of the CM equations is used to discuss possible effects of modulational instability on scenarios for the transition to turbulence in both collisional and collisionless cases.
Theory of edge-state optical absorption in two-dimensional transition metal dichalcogenide flakes
Trushin, Maxim; Kelleher, Edmund J. R.; Hasan, Tawfique
2016-10-01
We develop an analytical model to describe sub-band-gap optical absorption in two-dimensional semiconducting transition metal dichalcogenide (s-TMD) nanoflakes. The material system represents an array of few-layer molybdenum disulfide crystals, randomly orientated in a polymer matrix. We propose that optical absorption involves direct transitions between electronic edge states and bulk bands, depends strongly on the carrier population, and is saturable with sufficient fluence. For excitation energies above half the band gap, the excess energy is absorbed by the edge-state electrons, elevating their effective temperature. Our analytical expressions for the linear and nonlinear absorption could prove useful tools in the design of practical photonic devices based on s-TMDs.
Fluid-solid transition in simple systems using density functional theory
Energy Technology Data Exchange (ETDEWEB)
Bharadwaj, Atul S.; Singh, Yashwant [Department of Physics, Banaras Hindu University, Varanasi-221 005 (India)
2015-09-28
A free energy functional for a crystal which contains both the symmetry-conserved and symmetry-broken parts of the direct pair correlation function has been used to investigate the fluid-solid transition in systems interacting via purely repulsive Weeks-Chandler-Anderson Lennard–Jones potential and the full Lennard–Jones potential. The results found for freezing parameters for the fluid-face centred cubic crystal transition are in very good agreement with simulation results. It is shown that although the contribution made by the symmetry broken part to the grand thermodynamic potential at the freezing point is small compared to that of the symmetry conserving part, its role is crucial in stabilizing the crystalline structure and on values of the freezing parameters.
Statistical theory of L-H transition and its implication to threshold database
Energy Technology Data Exchange (ETDEWEB)
Itoh, Sanae-I. [Kyushu Univ., Research Institute for Applied Mechanics, Kasuga, Fukuoka (Japan); Itoh, Kimitaka; Toda, Shinichiro [National Inst. for Fusion Science, Toki, Gifu (Japan)
2003-01-01
A statistical model for the bifurcation of the radial electric field E{sub r} is analyzed in view of describing L-H transitions of toroidal plasmas. Noise in micro fluctuations is shown to lead to random changes of E{sub r}, if a deterministic approach allows for more than one solution. The probability density function for and the ensemble average of E{sub r} are obtained. The L-to-H and the H-to-L transition probabilities are calculated, and the effective phase limit is derived. Due to the suppression of turbulence by shear in E{sub r}, the limit deviates from Maxwell's rule. (author)
Theory of two-photon micromaser: competition among different transition processes
Institute of Scientific and Technical Information of China (English)
Sun Wei-Hui; Du Si-De; Chen Xiao-Shuang
2006-01-01
We have investigated the steady-state cavity-field properties of a single-mode two-photon micromaser when the atoms in a cascade three-level configuration are initially prepared in a mixture of the upper and intermediate states. The mean photon number, trapping state and sub-Poissonian effect are discussed with upper (intermediate)-state population changing from 1(0) to 0(1). These properties are very different from those in a pure two- or one-photon transition process, due to the competition among different transition processes. In particular, the trapping states of nonzero photons are discovered in this system under some conditions, which is contrary to the previous findings.
Bosonization in SU(N) Gauge Field Theory in Terms of Phase Transition of Second Kind
Koshelkin, A V
2012-01-01
Bosonization of the strong interacting matter as a process of arising observable hadrons is studied in terms of the phase transition of the second kind. The spectrum of bosons which is free from the zero point energy is derived . The calculated boson mass is found to depend self-consistently on both the amplitude of a gauge field and quark mass. In the framework of the quasi-classical model a hadron mass is calculated in the case of bosonization into pions.
2015-05-01
transitions take place in steam generators, heat exchangers, and various pipelines . The accompanying thermal effects make multiphase flow a widely... designed , using functional entropy variables and a new temporal scheme employing a family of new quadrature rules. We show that the resulting fully discrete...relations in the presence of non- local effects. A new thermodynamically consistent algorithm for the van der Waals model is designed , using functional
Radiationless transitions to atomic M 1,2,3 shells - Results of relativistic theory
Chen, M. H.; Crasemann, B.; Mark, H.
1983-01-01
Radiationless transitions filling vacancies in atomic M1, M2, and M3 subshells have been calculated relativistically with Dirac-Hartree-Slater wave functions for ten elements with atomic numbers 67-95. Results are compared with those of nonrelativistic calculations and experiment. Relativistic effects are found to be significant. Limitations of an independent-particle model for the calculation of Coster-Kronig rates are noted.
Using archetypes and transitions theory to help patients move from active treatment to survivorship.
Rancour, Patrice
2008-12-01
Nurses historically have used the medical model to assess and intervene when individuals move transitionally into and out of the role of patients with cancer. Although assessing for clinical depression or other medical model designations is appropriate, using this as the sole model for helping patients with cancer emerge from their illness experiences and into the role of survivorship may rob them of the opportunity to actively use the illness for spiritual growth and self-actualization. The transition process is classified into three distinct stages: endings, the neutral zone, and beginnings. Each is characterized by its own unique qualities and challenges. Jungian metaphors and archetypes also can be used to evoke powerful images that help survivors find depth of meaning in their suffering and enhance healing. Nurses often are in ideal positions to create such healing experiences by helping survivors recognize "shadow" emotional experiences stemming from the recovery process, accepting the emotions as normal transitional phenomena, and using them to develop compassion for others. Individuals, therefore, are presented with opportunities to imagine newly emerging life purposes that far exceed their identification as survivors.
Electric transition dipole moment in pre-Born-Oppenheimer molecular structure theory.
Simmen, Benjamin; Mátyus, Edit; Reiher, Markus
2014-10-21
This paper presents the calculation of the electric transition dipole moment in a pre-Born-Oppenheimer framework. Electrons and nuclei are treated equally in terms of the parametrization of the non-relativistic total wave function, which is written as a linear combination of basis functions constructed from explicitly correlated Gaussian functions and the global vector representation. The integrals of the electric transition dipole moment are derived corresponding to these basis functions in both the length and the velocity representation. The calculations are performed in laboratory-fixed Cartesian coordinates without relying on coordinates which separate the center of mass from the translationally invariant degrees of freedom. The effect of the overall motion is eliminated through translationally invariant integral expressions. The electric transition dipole moment is calculated between two rovibronic levels of the H2 molecule assignable to the lowest rovibrational states of the X (1)Σ(g)(+) and B (1)Σ(u)(+) electronic states in the clamped-nuclei framework. This is the first evaluation of this quantity in a full quantum mechanical treatment without relying on the Born-Oppenheimer approximation.
Mott-Hubbard and Anderson transitions in dynamical mean-field theory
Energy Technology Data Exchange (ETDEWEB)
Byczuk, Krzysztof [Institute of Theoretical Physics, Warsaw University, ul. Hoza 69, PL-00-681 Warsaw (Poland)]. E-mail: byczuk@fuw.edu.pl; Hofstetter, Walter [Condensed Matter Theory Group, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Vollhardt, Dieter [Theoretical Physics III, Center for Electronic Correlations and Magnetism, Institute for Physics, University of Augsburg, D-86135 Augsburg (Germany)
2005-04-30
The Anderson-Hubbard Hamiltonian at half-filling is investigated within dynamical mean-field theory at zero temperature. The local density of states is calculated by taking the geometric and arithmetic mean, respectively. The non-magnetic ground state phase diagrams obtained within the different averaging schemes are compared.
New N=1 dualities from orientifold transitions - Part II: String Theory
García-Etxebarria, Iñaki; Wrase, Timm
2013-01-01
We present a string theoretical description, given in terms of branes and orientifolds wrapping vanishing cycles, of the dual pairs of gauge theories analyzed in 1210.7799. Based on the resulting construction we argue that the duality that we observe in field theory is inherited from S-duality of type IIB string theory. We analyze in detail the complex cone over the zeroth del Pezzo surface and discuss an infinite family of orbifolds of flat space. For the del Pezzo case we describe the system in terms of large volume objects, and show that in this language the duality can be understood from the strongly coupled behavior of the O7^+ plane, which we analyze using simple F-theory considerations. For all cases we also give a different argument based on the existence of appropriate torsional components of the 3-form flux lattice. Along the way we clarify some aspects of the description of orientifolds in the derived category of coherent sheaves, and in particular we discuss the important role played by exotic ori...
Matsui, Toru; Kitagawa, Yasutaka; Shigeta, Yasuteru; Okumura, Mitsutaka
2013-07-09
We propose an accurate scheme to evaluate the redox potential of a wide variety of transition metal complexes by adding a charge-dependent correction term for a counterion around the charged complexes, which is based on Generalized Born theory, to the solvation energy. The mean absolute error (MAE) toward experimental redox potentials of charged complexes is considerably reduced from 0.81 V (maximum error 1.22 V) to 0.22 V (maximum error 0.50 V). We found a remarkable exchange-correlation functional dependence on the results rather than the basis set ones. The combination of Wachters+f (for metal) and 6-31++G(d,p) (for other atoms) with the B3LYP functional gives the least MAE 0.15 V for the test complexes. This scheme is applicable to other solvents, and heavier transition metal complexes such as M1(CO)5(pycn) (M1 = Cr, Mo, W), M2(mnt)2 (M2 = Ni, Pd, Pt), and M3(bpy)3 (M3 = Fe, Ru, Os) with the same quality.
Tretyakov, Nikita; Papadopoulos, Periklis; Vollmer, Doris; Butt, Hans-Jürgen; Dünweg, Burkhard; Daoulas, Kostas Ch.
2016-10-01
Classical density functional theory is applied to investigate the validity of a phenomenological force-balance description of the stability of the Cassie state of liquids on substrates with nanoscale corrugation. A bulk free-energy functional of third order in local density is combined with a square-gradient term, describing the liquid-vapor interface. The bulk free energy is parameterized to reproduce the liquid density and the compressibility of water. The square-gradient term is adjusted to model the width of the water-vapor interface. The substrate is modeled by an external potential, based upon the Lennard-Jones interactions. The three-dimensional calculation focuses on substrates patterned with nanostripes and square-shaped nanopillars. Using both the force-balance relation and density-functional theory, we locate the Cassie-to-Wenzel transition as a function of the corrugation parameters. We demonstrate that the force-balance relation gives a qualitatively reasonable description of the transition even on the nanoscale. The force balance utilizes an effective contact angle between the fluid and the vertical wall of the corrugation to parameterize the impalement pressure. This effective angle is found to have values smaller than the Young contact angle. This observation corresponds to an impalement pressure that is smaller than the value predicted by macroscopic theory. Therefore, this effective angle embodies effects specific to nanoscopically corrugated surfaces, including the finite range of the liquid-solid potential (which has both repulsive and attractive parts), line tension, and the finite interface thickness. Consistently with this picture, both patterns (stripes and pillars) yield the same effective contact angles for large periods of corrugation.
4fn-->4fn-15d transitions of the heavy lanthanides: Experiment and theory
van Pieterson, L.; Reid, M. F.; Burdick, G. W.; Meijerink, A.
2002-01-01
The 4fn-->4fn-15d(fd) excitation spectra of the heavy lanthanides (Tb3+, Dy3+, Ho3+, Er3+, Tm3+, and Yb3+) incorporated in LiYF4, CaF2, and YPO4 are investigated in the ultraviolet and vacuum-ultraviolet spectral region (100-275 nm). Spin-forbidden transitions as well as spin-allowed transitions are observed for all heavy lanthanides. In the excitation spectra the crystal-field splitting of the 5d electron can be clearly observed. Fine structure (zero-phonon lines and vibronic lines) is observed for the transition to the lowest 5d crystal-field component, for both the high-spin and low-spin fd bands. Energy-level and intensity calculations are performed by an extension of the commonly used model for energy-level calculations of 4fn states. A good agreement between experimental and simulated spectra is obtained, using parameters that describe the 5d crystal-field splitting (from the spectra of Ce3+), the parameters for the splitting of the 4fn-1 core (from the literature on energy-level calculations for 4fn states) and parameters for the spin-orbit coupling of the 5d electron and the Coulomb interaction between 4f and 5d electrons (from atomic ab initio calculations using the computer code of Cowan). To improve the agreement between the model and experiment, the 5d crystal-field parameters were adjusted slightly to correct for the decreasing crystal-field strength for the heavier rare earths due to the lanthanide contraction. The f-d interaction parameters in the fluoride host lattices were reduced to about 67% of the calculated free-ion values in order to compensate for the nephelauxetic effect.
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U.S. Department of Health & Human Services — This website provides demographic information about laboratories, including CLIA number, facility name and address, where the laboratory testing is performed, the...
Alpha-helix <-> random coil phase transition: analysis of ab initio theory predictions
DEFF Research Database (Denmark)
Solov'yov, Ilia; Yakubovich, Alexander V.; Solov'yov, Andrey V.
2008-01-01
In the present paper we present results of calculations obtained with the use of the theoretical method described in our preceding paper [Eur. Phys. J. D, DOI 10.1140/epjd/e2007-00328-9] and perform detail analysis of -helix random coil transition in alanine polypeptides of different length. We...... have obtained same thermodynamical characteristics from the use of molecular dynamics simulations and compared them with the results of the new statistical mechanics approach. The comparison proves the validity of the statistical mechanic approach and establishes its accuracy....
Energy Technology Data Exchange (ETDEWEB)
Stoessel, J.P.; Wolynes, P.G.
1989-01-01
With analogy to the ''highly accurate'' summation of cluster diagrams for hard sphere fluids a la Carnahan-Starling, we present a simple, real space free energy density functional for arbitrary potential systems, based on the generalization of the second virial coefficient to inhomogeneous systems which, when applied to hard sphere, soft-sphere, and Lennard-Jones freezing, yield melting characteristics in remarkable agreement with experiment. Implications for the liquid-glass transition in all three potential systems are also presented. 45 refs., 7 figs., 1 tab.
Töws, W; Pastor, G M
2015-11-20
Exact calculated time evolutions in the framework of a many-electron model of itinerant magnetism provide new insights into the laser-induced ultrafast demagnetization observed in ferromagnetic (FM) transition metal thin films. The interplay between local spin-orbit interactions and interatomic hopping is shown to be at the origin of the observed postexcitation breakdown of FM correlations between highly stable local magnetic moments. The mechanism behind spin- and angular-momentum transfer is revealed from a microscopic perspective by rigorously complying with all fundamental conservation laws. An energy-resolved analysis of the time evolution shows that the efficiency of the demagnetization process reaches almost 100% in the excited states.
Directory of Open Access Journals (Sweden)
Melanie Swan
2010-02-01
Full Text Available Information optimization is a centerpiece phenomenon in the universe. It develops from simplicity, then continuously breaks symmetry and cycles through instability to progress to increasingly dense nodes of complexity and diversity. Intelligence has arisen as the information optimization node with the greatest complexity. A contemporary imbalance is presented in that exponentially growing technology could be poised as a potential sole successor to human intelligence. A complex dynamical system is emerging in response, the engineering of life into technology. Numerous network elements are developing which could self-organize into the next node of symmetry, a phase transition in intelligence.
Random pinning glass transition: hallmarks, mean-field theory and renormalization group analysis.
Cammarota, Chiara; Biroli, Giulio
2013-03-28
We present a detailed analysis of glass transitions induced by pinning particles at random from an equilibrium configuration. We first develop a mean-field analysis based on the study of p-spin spherical disordered models and then obtain the three-dimensional critical behavior by the Migdal-Kadanoff real space renormalization group method. We unveil the important physical differences with the case in which particles are pinned from a random (or very high temperature) configuration. We contrast the pinning particles approach to the ones based on biasing dynamical trajectories with respect to their activity and on coupling to equilibrium configurations. Finally, we discuss numerical and experimental tests.
Theory of optically forbidden d-d transitions in strongly correlated crystals.
Katsnelson, M I; Lichtenstein, A I
2010-09-29
A general multiband formulation of the linear and nonlinear optical response functions for realistic models of correlated crystals is presented. Dipole-forbidden d-d optical transitions originate from vertex functions, which we consider assuming the locality of an irreducible four-leg vertex. The unified formulation for second- and third-order response functions in terms of the three-leg vertex is suitable for practical calculations in solids. We illustrate the general approach by consideration of intra-atomic spin-flip contributions, with an energy of 2J, where J is a Hund exchange, in the simplest two-orbital model.
Traditional fire-use, landscape transition, and the legacies of social theory past.
Coughlan, Michael R
2015-12-01
Fire-use and the scale and character of its effects on landscapes remain hotly debated in the paleo- and historical-fire literature. Since the second half of the nineteenth century, anthropology and geography have played important roles in providing theoretical propositions and testable hypotheses for advancing understandings of the ecological role of human-fire-use in landscape histories. This article reviews some of the most salient and persistent theoretical propositions and hypotheses concerning the role of humans in historical fire ecology. The review discusses this history in light of current research agendas, such as those offered by pyrogeography. The review suggests that a more theoretically cognizant historical fire ecology should strive to operationalize transdisciplinary theory capable of addressing the role of human variability in the evolutionary history of landscapes. To facilitate this process, researchers should focus attention on integrating more current human ecology theory into transdisciplinary research agendas.
Brillouin-Wigner theory for Floquet topological phase transitions in spin-orbit-coupled materials
Mohan, Priyanka; Saxena, Ruchi; Kundu, Arijit; Rao, Sumathi
2016-12-01
We develop the high-frequency expansion based on the Brillouin-Wigner (B-W) perturbation theory for driven systems with spin-orbit coupling which is applicable to the cases of silicene, germanene, and stanene. We compute the effective Hamiltonian in the zero-photon subspace not only to order O (ω-1) but by keeping all the important terms to order O (ω-2) and obtain the photoassisted correction terms to both the hopping and the spin-orbit terms, as well as longer-ranged hopping terms. We then use the effective static Hamiltonian to compute the phase diagram in the high-frequency limit and compare it with the results of direct numerical computation of the Chern numbers of the Floquet bands and show that at sufficiently large frequencies, the B-W theory high-frequency expansion works well even in the presence of spin-orbit-coupling terms.
The Deconfinement Phase Transition of Sp(2) and Sp(3) Yang-Mills Theories in 2+1 and 3+1 Dimensions
Holland, K; Wiese, U J
2003-01-01
Some time ago, Svetitsky and Yaffe have argued that -- if the deconfinement phase transition of a (d+1)-dimensional Yang-Mills theory with gauge group G is second order -- it should be in the universality class of a d-dimensional spin model symmetric under the center of G. For d=3 these arguments have been confirmed numerically only in the SU(2) case with center Z(2), simply because all SU(N) Yang-Mills theories with N>=3 seem to have non-universal first order phase transitions. The symplectic groups Sp(N) also have the center Z(2) and provide another extension of SU(2) = Sp(1) to general N. Using lattice simulations, we find that the deconfinement phase transition of Sp(2) Yang-Mills theory is first order in 3+1 dimensions, while in 2+1 dimensions stronger fluctuations induce a second order transition. In agreement with the Svetitsky-Yaffe conjecture, for (2+1)-d Sp(2) Yang-Mills theory we find the universal critical behavior of the 2-d Ising model. For Sp(3) Yang-Mills theory the transition is first order b...
Institute of Scientific and Technical Information of China (English)
HE Xiang; WANG Fan
2006-01-01
@@ Thioaldehydes and thioketones are candidates of new photoluminescence materials. The time-dependent density functional theory is applied to calculate the absorption and emission wavelengths of ten thiocarbonyl compounds using both B3LYP and PBE0 functionals. The theoretical results are in agreement with the measurable ones.Furthermore, it is found that the maximum absorption and emission wavelengths are linearly correlated to the C-S bond lengths.
Population pressure and fertility in pre-transition Thailand.
VanLandingham, M; Hirschman, C
2001-11-01
Before the demographic transition in Thailand, fertility was high, but not uniformly so. As in other pre-transition settings, Thai fertility responded to pressures and opportunities created by socioeconomic structure and land availability. Drawing upon provincial data from the 1947 and 1960 censuses of Thailand, we find a strong 'frontier effect' on Thai fertility in the 1950s. Fertility was higher in sparsely settled frontier provinces and lower in provinces with higher population density relative to cultivatable land. This finding is robust and holds up with controls for agricultural employment, land quality, and the sex ratio (an indicator of sex-selective migration). The effect of population pressure lowers the likelihood of marriage and of marital fertility. The findings from Thailand are consistent with the research of Easterlin on the nineteenth century United States and with other pre-transition societies. We suggest how demographic transition theory might be broadened to include fertility dynamics in pre-transition societies.
PROBLEMS OF TRANSITION TO IFRS IN THE AGRICULTURAL SECTOR: THEORY AND PRACTICE
Directory of Open Access Journals (Sweden)
Kraskova A. A.
2015-10-01
Full Text Available The article presents aspects of the efficiency of the international financial reporting standards (IFRS in the accounting practice of agricultural enterprises by basic organizational components, defines stages of the application of certain IFRS elements in the preparation of reporting of the agricultural sector enterprises. First of all, agricultural enterprises will face problems of the transition to IFRS. This is associated with peculiarities of the agricultural production, which are determined by the natural and social factors and affect the organization of accounting: agricultural production is seasonal, this is why the production cycle doesn’t coincide with the calendar year; the land is the basic means of production, animals and plants act as a specific means of production; timescales of plant ripening and animal breeding determine the obtainment of the end product. Analysis of the difficulties of the agricultural organizations’ transition to IFRS showed different views in the scientific and professional community regarding the valuation of assets and liabilities and biological assets accounting. Choice of experts responsible for the preparation of reporting according to IFRS is an important issue that requires additional expenses for hiring highly qualified specialists or the creation of a special department, which is fully agreeable to international standards. Success of the reporting preparation according to IFRS requires the process optimization with the usage of modern information technologies. Introduction of IFRS to the accounting practices of agricultural enterprises implies changes of the national regulatory framework of accounting, reporting and taxation
Luo, Sijie; Averkiev, Boris; Yang, Ke R; Xu, Xuefei; Truhlar, Donald G
2014-01-14
The 3d-series transition metals (also called the fourth-period transition metals), Sc to Zn, are very important in industry and biology, but they provide unique challenges to computing the electronic structure of their compounds. In order to successfully describe the compounds by theory, one must be able to describe their components, in particular the constituent atoms and cations. In order to understand the ingredients required for successful computations with density functional theory, it is useful to examine the performance of various exchange-correlation functionals; we do this here for 4s(N)3d(N') transition-metal atoms and their cations. We analyze the results using three ways to compute the energy of the open-shell states: the direct variational method, the weighted-averaged broken symmetry (WABS) method, and a new broken-symmetry method called the reinterpreted broken symmetry (RBS) method. We find the RBS method to be comparable in accuracy with the WABS method. By examining the overall accuracy in treating 18 multiplicity-changing excitations and 10 ionization potentials with the RBS method, 10 functionals are found to have a mean-unsigned error of systems, the M06-L functional is the most accurate. And by combining the results with our previous studies of p-block and 4d-series elements as well as databases for alkyl bond dissociation, main-group atomization energies, and π-π noncovalent interactions, we find five functionals, namely, PW6B95, MPW1B95, M08-SO, SOGGA11-X, and MPWB1K, to be highly recommended. We also studied the performance of PW86 and C09 exchange functionals, which have drawn wide interest in recent studies due to their claimed ability to reproduce Hartree-Fock exchange at long distance. By combining them with four correlation functionals, we find the performance of the resulting functionals disappointing both for 3d transition-metal chemistry and in broader tests, and thus we do not recommend PW86 and C09 as components of generalized
Tanaka, Hiromasa; Nishibayashi, Yoshiaki; Yoshizawa, Kazunari
2016-05-17
Nitrogen fixation is an essential chemical process both biologically and industrially. Since the discovery of the first transition-metal-dinitrogen complex in 1965, a great deal of effort has been devoted to the development of artificial nitrogen fixation systems that work under mild reaction conditions. However, the transformation of chemically inert dinitrogen using homogeneous catalysts is still challenging because of the difficulty in breaking the strong triple bond of dinitrogen, and a very limited number of transition metal complexes have exhibited the catalytic activity for the direct transformation of dinitrogen into ammonia with low turnover numbers. To develop more effective nitrogen fixation systems, it is necessary to retrieve as much information as possible from the limited successful examples. Computational chemistry will provide valuable insights in the understanding of the reaction mechanisms involving unstable intermediates that are hard to isolate or characterize. We have been applying it for clarifying detailed mechanisms of dinitrogen activation and functionalization by transition metal complexes as well as for designing new catalysts for more effective nitrogen fixation. This Account summarizes recent progress in the elucidation of catalytic mechanisms of nitrogen fixation by using mono- and dinuclear molybdenum complexes, as well as cubane-type metal-sulfido clusters from a theoretical point of view. First, we briefly introduce experimental and theoretical contributions to the elucidation of the reaction mechanism of nitrogen fixation catalyzed by a mononuclear Mo-triamidoamine complex. Special attention is paid to our recent studies on Mo-catalyzed nitrogen fixation using dinitrogen-bridged dimolybdenum complexes. A possible catalytic mechanism is proposed based on theoretical and experimental investigations. The catalytic mechanism involves the formation of a monuclear molybdenum-nitride (Mo≡N) intermediate, as well as the regeneration of
Directory of Open Access Journals (Sweden)
Agustín Maraver
1996-02-01
Full Text Available This study tries to make a balance between the internal logic of the “shock therapies” which were applied in Central and Eastern Europe through adjustment programmes and structural reform in order to open up their economies “inside out” and integrate them into the world economy. From these interventionist policies, applied by the State by the political forces which wanted to put an end to the communist nomenklatura, a new social class structure did not emerge spontaneously as foreseen by neoliberal theory.
Ponson, Laurent; Pindra, Nadjime
2017-05-01
The dynamics of a planar crack propagating within a brittle disordered material is investigated numerically. The fracture front evolution is described as the depinning of an elastic line in a random field of toughness. The relevance of this approach is critically tested through the comparison of the roughness front properties, the statistics of avalanches, and the local crack velocity distribution with experimental results. Our simulations capture the main features of the fracture front evolution as measured experimentally. However, some experimental observations such as the velocity distribution are not consistent with the behavior of an elastic line close to the depinning transition. This discrepancy suggests the presence of another failure mechanism not included in our model of brittle failure.
Phase-transition Theory of Kerr Black Holes in the Electromagnetic Field
Liao, Yi; Gong, Xiao-Bo; Wu, Jian-Sheng
2017-02-01
For a Kerr black hole (KBH) with spin J and mass M in a steady electromagnetic field, a special Wald vacuum solution (WVS) has been found in the case of the no-source uniform field. For WVS, the Meissner effect (ME) occurs only in the the extreme KBH, where M2/J = 1, in this case, the magnetic field is totally excluded from the event horizon (EH) of KBH. However, WVS does not consider the Hawking radiation (HR) but treats KBH as an absolutely black body. If HR is added , researchers believe that the condition is not so restricted and it is possible for ME to occur in the less-extreme case. How less is the “less-extreme case”? This paper tries to answer this question. Since the Hawking temperature TH of KBH defined by HR is proportional to the surface gravity κ at the EH, this question is actually about the so-called existence/non-existence of ME (ME/NME) or superconducting phase transition. In this paper, we study the connection between the superconductivity of KBH-EH and the existence of Weyl fermion. Using thermodynamic formulas and the KBH state equation, we prove that the inherent-parameter condition for ME to occur is {M}2/J≤slant {ε }c=1.5 in force-free fields whether it be in the simple axisymmetric vacuum zero source case or in the non-zero source case, which can be described by the nonlinear Grad–Shafranov equation. We suggest that this is a second-order phase transition and calculate the critical exponents δ = 1 and η = 1/2 for the specific heat diverging at constant J.
Numerical study of large-N phase transition of smeared Wilson loops in 4D pure YM theory
Lohmayer, Robert
2011-01-01
In Euclidean four-dimensional SU(N) pure gauge theory, eigenvalue distributions of Wilson loop parallel transport matrices around closed spacetime curves show non-analytic behavior (a 'large-N phase transition') at a critical size of the curve. We focus mainly on an observable composed of traces of the Wilson loop operator in all totally antisymmetric representations, which is regularized with the help of smearing. By studying sequences of square Wilson loops on a hypercubic lattice with standard Wilson action, it is shown that this observable has a nontrivial continuum limit as a function of the physical size of the loop. We furthermore present (preliminary) numerical results confirming that, for large N, the N dependence in the critical regime is governed by the universal exponents 1/2 and 3/4 as expected (Burgers universality).
The origin of magnetism in transition metal-doped ZrO2 thin films: Experiment and theory
Hong, Nguyenhoa
2013-10-04
We have investigated the magnetic properties of Fe/Co/Ni-doped ZrO 2 laser ablated thin films in comparison with the known results of Mn-doped ZrO2, which is thought to be a promising material for spintronics applications. It is found that doping with a transition metal can induce room temperature ferromagnetism in \\'fake\\' diamond. Theoretical analysis based on density functional theory confirms the experimental measurements, by revealing that the magnetic moments of Mn- and Ni-doped ZrO2 thin films are much larger than that of Fe- or Co-doped ZrO2 thin films. Most importantly, our calculations confirm that Mn- and Ni-doped ZrO2 show a ferromagnetic ground state in comparison to Co- and Fe-doped ZrO 2, which favor an antiferromagnetic ground state. © 2013 IOP Publishing Ltd.
Wang, Bi-Yao; Li, Ze-Rong; Tan, Ning-Xin; Yao, Qian; Li, Xiang-Yuan
2013-04-25
We present a further interpretation of reaction class transition state theory (RC-TST) proposed by Truong et al. for the accurate calculation of rate coefficients for reactions in a class. It is found that the RC-TST can be interpreted through the isodesmic reaction method, which is usually used to calculate reaction enthalpy or enthalpy of formation for a species, and the theory can also be used for the calculation of the reaction barriers and reaction enthalpies for reactions in a class. A correction scheme based on this theory is proposed for the calculation of the reaction barriers and reaction enthalpies for reactions in a class. To validate the scheme, 16 combinations of various ab initio levels with various basis sets are used as the approximate methods and CCSD(T)/CBS method is used as the benchmarking method in this study to calculate the reaction energies and energy barriers for a representative set of five reactions from the reaction class: R(c)CH(R(b))CR(a)CH2 + OH(•) → R(c)C(•)(R(b))CR(a)CH2 + H2O (R(a), R(b), and R(c) in the reaction formula represent the alkyl or hydrogen). Then the results of the approximate methods are corrected by the theory. The maximum values of the average deviations of the energy barrier and the reaction enthalpy are 99.97 kJ/mol and 70.35 kJ/mol, respectively, before correction and are reduced to 4.02 kJ/mol and 8.19 kJ/mol, respectively, after correction, indicating that after correction the results are not sensitive to the level of the ab initio method and the size of the basis set, as they are in the case before correction. Therefore, reaction energies and energy barriers for reactions in a class can be calculated accurately at a relatively low level of ab initio method using our scheme. It is also shown that the rate coefficients for the five representative reactions calculated at the BHandHLYP/6-31G(d,p) level of theory via our scheme are very close to the values calculated at CCSD(T)/CBS level. Finally, reaction
Epigenetic game theory: How to compute the epigenetic control of maternal-to-zygotic transition
Wang, Qian; Gosik, Kirk; Xing, Sujuan; Jiang, Libo; Sun, Lidan; Chinchilli, Vernon M.; Wu, Rongling
2017-03-01
Epigenetic reprogramming is thought to play a critical role in maintaining the normal development of embryos. How the methylation state of paternal and maternal genomes regulates embryogenesis depends on the interaction and coordination of the gametes of two sexes. While there is abundant research in exploring the epigenetic interactions of sperms and oocytes, a knowledge gap exists in the mechanistic quantitation of these interactions and their impact on embryo development. This review aims at formulating a modeling framework to address this gap through the integration and synthesis of evolutionary game theory and the latest discoveries of the epigenetic control of embryo development by next-generation sequencing. This framework, named epigenetic game theory or epiGame, views embryogenesis as an ecological system in which two highly distinct and specialized gametes coordinate through either cooperation or competition, or both, to maximize the fitness of embryos under Darwinian selection. By implementing a system of ordinary differential equations, epiGame quantifies the pattern and relative magnitude of the methylation effects on embryogenesis by the mechanisms of cooperation and competition. epiGame may gain new insight into reproductive biology and can be potentially applied to design personalized medicines for genetic disorder intervention.
Random Matrix Theory for the Hermitian Wilson Dirac Operator and the chGUE-GUE Transition
Akemann, Gernot
2011-01-01
We introduce a random two-matrix model interpolating between a chiral Hermitian (2n+nu)x(2n+nu) matrix and a second Hermitian matrix without symmetries. These are taken from the chiral Gaussian Unitary Ensemble (chGUE) and Gaussian Unitary Ensemble (GUE), respectively. In the microscopic large-n limit in the vicinity of the chGUE (which we denote by weakly non-chiral limit) this theory is in one to one correspondence to the partition function of Wilson chiral perturbation theory in the epsilon regime, such as the related two matrix-model previously introduced in refs. [20,21]. For a generic number of flavours and rectangular block matrices in the chGUE part we derive an eigenvalue representation for the partition function displaying a Pfaffian structure. In the quenched case with nu=0,1 we derive all spectral correlations functions in our model for finite-n, given in terms of skew-orthogonal polynomials. The latter are expressed as Gaussian integrals over standard Laguerre polynomials. In the weakly non-chira...
Goodpaster, Jason D; Barnes, Taylor A; Manby, Frederick R; Miller, Thomas F
2012-12-14
Density functional theory (DFT) embedding provides a formally exact framework for interfacing correlated wave-function theory (WFT) methods with lower-level descriptions of electronic structure. Here, we report techniques to improve the accuracy and stability of WFT-in-DFT embedding calculations. In particular, we develop spin-dependent embedding potentials in both restricted and unrestricted orbital formulations to enable WFT-in-DFT embedding for open-shell systems, and develop an orbital-occupation-freezing technique to improve the convergence of optimized effective potential calculations that arise in the evaluation of the embedding potential. The new techniques are demonstrated in applications to the van-der-Waals-bound ethylene-propylene dimer and to the hexa-aquairon(II) transition-metal cation. Calculation of the dissociation curve for the ethylene-propylene dimer reveals that WFT-in-DFT embedding reproduces full CCSD(T) energies to within 0.1 kcal/mol at all distances, eliminating errors in the dispersion interactions due to conventional exchange-correlation (XC) functionals while simultaneously avoiding errors due to subsystem partitioning across covalent bonds. Application of WFT-in-DFT embedding to the calculation of the low-spin/high-spin splitting energy in the hexaaquairon(II) cation reveals that the majority of the dependence on the DFT XC functional can be eliminated by treating only the single transition-metal atom at the WFT level; furthermore, these calculations demonstrate the substantial effects of open-shell contributions to the embedding potential, and they suggest that restricted open-shell WFT-in-DFT embedding provides better accuracy than unrestricted open-shell WFT-in-DFT embedding due to the removal of spin contamination.
Compressibility and structural stability of CeN from experiment and theory. The B1–B2 transition
DEFF Research Database (Denmark)
Staun Olsen, J.; Jørgensen, J.-E.; Gerward, L.
2012-01-01
The high-pressure structural stability of CeN is investigated by experiment and theory. Experiments are carried out by energy-dispersive X-ray diffraction and synchrotron radiation, using a diamond anvil cell, to a maximum pressure of 77GPa. The experimental results are in remarkably good agreement...... with ab initio calculations using the full-potential linear muffin-tin orbital method within the generalized gradient approximation (GGA). The experimental zero pressure bulk modulus is B0=156(3)GPa, the pressure derivative being constrained to B0′=4.00. The corresponding calculated data are B0=158.1GPa...... and B0′=3.3. We report here the first experimental observation of the transformation of CeN from the ambient B1 type crystal structure to the B2 type. The onset of the transition is in the range 65–70GPa, and the relative volume change at the transition is ΔV/V=−10.9(3)%. These data compare well...
Yu, Tang-Qing; Lapelosa, Mauro; Vanden-Eijnden, Eric; Abrams, Cameron F
2015-03-04
We use Markovian milestoning molecular dynamics (MD) simulations on a tessellation of the collective variable space for CO localization in myoglobin to estimate the kinetics of entry, exit, and internal site-hopping. The tessellation is determined by analysis of the free-energy surface in that space using transition-path theory (TPT), which provides criteria for defining optimal milestones, allowing short, independent, cell-constrained MD simulations to provide properly weighted kinetic data. We coarse grain the resulting kinetic model at two levels: first, using crystallographically relevant internal cavities and their predicted interconnections and solvent portals; and second, as a three-state side-path scheme inspired by similar models developed from geminate recombination experiments. We show semiquantitative agreement with experiment on entry and exit rates and in the identification of the so-called "histidine gate" at position 64 through which ≈90% of flux between solvent and the distal pocket passes. We also show with six-dimensional calculations that the minimum free-energy pathway of escape through the histidine gate is a "knock-on" mechanism in which motion of the ligand and the gate are sequential and interdependent. In total, these results suggest that such TPT simulations are indeed a promising approach to overcome the practical time-scale limitations of MD to allow reliable estimation of transition mechanisms and rates among metastable states.
Energy Technology Data Exchange (ETDEWEB)
Arnold, Thorsten; Siegmund, Marc; Pankratov, Oleg, E-mail: thorsten.arnold@physik.uni-erlangen.de, E-mail: marc.siegmund@physik.uni-erlangen.de [Lehrstuhl fuer Theoretische Festkoerperphysik, Universitaet Erlangen-Nuernberg, Staudtstrasse 7 B2, D-91058 Erlangen (Germany)
2011-08-24
We apply exact-exchange spin-density functional theory in the Krieger-Li-Iafrate approximation to interacting electrons in quantum rings of different widths. The rings are threaded by a magnetic flux that induces a persistent current. A weak space and spin symmetry breaking potential is introduced to allow for localized solutions. As the electron-electron interaction strength described by the dimensionless parameter r{sub S} is increased, we observe-at a fixed spin magnetic moment-the subsequent transition of both spin sub-systems from the Fermi liquid to the Wigner crystal state. A dramatic signature of Wigner crystallization is that the persistent current drops sharply with increasing r{sub S}. We observe simultaneously the emergence of pronounced oscillations in the spin-resolved densities and in the electron localization functions indicating a spatial electron localization showing ferrimagnetic order after both spin sub-systems have undergone the Wigner crystallization. The critical r{sub S}{sup c} at the transition point is substantially smaller than in a fully spin-polarized system and decreases further with decreasing ring width. Relaxing the constraint of a fixed spin magnetic moment, we find that on increasing r{sub S} the stable phase changes from an unpolarized Fermi liquid to an antiferromagnetic Wigner crystal and finally to a fully polarized Fermi liquid.
Institute of Scientific and Technical Information of China (English)
Liu Li; Wei Jian-Jun; An Xin-You; Wang Xue-Min; Liu Hui-Na; Wu Wei-Dong
2011-01-01
The phase transition of gallium phosphide (GaP) from zinc-blende (ZB) to a rocksalt (RS) structure is investigated by the plane-wave pseudopotential density functional theory (DFT).Lattice constant a0,elastic constants cij,bulk modulus B0 and the pressure derivative of bulk modulus B'0 are calculated.The results are in good agreement with numerous experimental and theoretical data.From the usual condition of equal enthalpies,the phase transition from the ZB to the RS structure occurs at 21.9 GPa,which is close to the experimental value of 22.0 GPa.The elastic properties of GaP with the ZB structure in a pressure range from 0 GPa to 21.9 GPa and those of the RS structure in a pressure range of pressures from 21.9 GPa to 40 GPa are obtained.According to the quasi-harmonic Debye model,in which the phononic effects are considered,the normalized volume V/Vo,the Debye temperature θ,the heat capacity Cv and the thermal expansion coefficient α are also discussed in a pressure range from 0 GPa to 40 GPa and a temperature range from 0 K to 1500 K.
Arnold, Thorsten; Siegmund, Marc; Pankratov, Oleg
2011-08-24
We apply exact-exchange spin-density functional theory in the Krieger-Li-Iafrate approximation to interacting electrons in quantum rings of different widths. The rings are threaded by a magnetic flux that induces a persistent current. A weak space and spin symmetry breaking potential is introduced to allow for localized solutions. As the electron-electron interaction strength described by the dimensionless parameter r(S) is increased, we observe-at a fixed spin magnetic moment-the subsequent transition of both spin sub-systems from the Fermi liquid to the Wigner crystal state. A dramatic signature of Wigner crystallization is that the persistent current drops sharply with increasing r(S). We observe simultaneously the emergence of pronounced oscillations in the spin-resolved densities and in the electron localization functions indicating a spatial electron localization showing ferrimagnetic order after both spin sub-systems have undergone the Wigner crystallization. The critical r(S)(c) at the transition point is substantially smaller than in a fully spin-polarized system and decreases further with decreasing ring width. Relaxing the constraint of a fixed spin magnetic moment, we find that on increasing r(S) the stable phase changes from an unpolarized Fermi liquid to an antiferromagnetic Wigner crystal and finally to a fully polarized Fermi liquid.
Public school vandalism: toward a synthesis of theories and transition to paradigm analysis.
Tygart, C
1988-01-01
Public school vandalism was investigated with a sample of students in 7th through 12th grade. Vandalism was found to be the highest in Grade 7 and decreased progressively with each increase in grade level. Being from classes in the lowest academic track was the strongest predictor of school vandalism. For high school students, having committed acts of vandalism during their junior high year was the second strongest correlate of vandalism. Other correlates of vandalism were: coming from higher status families and being absent less from school. Vandals were no more negative toward themselves, their classes, and school in general than were other students. Vandals and nonvandals were rather uncritical of vandalism. While this research has relevance for several theories, it is suggested that delinquency and deviancy research move toward paradigm analysis.
Bassett-Gunter, Rebecca L; Levy-Milne, Ryna; Naylor, Patti Jean; Symons Downs, Danielle; Benoit, Cecilia; Warburton, Darren E R; Blanchard, Chris M; Rhodes, Ryan E
2013-07-06
Transitioning to parenthood is a major life event that may impact parents' personal lifestyles, yet there is an absence of theory-based research examining the impact of parenthood on motives for dietary behaviour. As a result, we are unaware of the social cognitive variables that predict eating behaviour among those transitioning to parenthood. The purpose of the study was to examine eating behaviour motives across 12 months within the framework of the theory of planned behavior (TPB) and compare these across groups of new parents, non-parents, and established parents. Non-parents (n = 92), new parents (n = 135), and established parents (n = 71) completed TPB questionnaires assessing attitudes, subjective norms, perceived behavioral control (PBC), and intentions and three day food records at baseline, and 6- and 12-months post-delivery (for parents) and 6- and 12-months post-baseline (for non-parents). Repeated measures ANOVAs revealed that among men, new- and established-parents had greater intentions to eat healthy compared to non-parents, F(2) = 3.59, p = .03. Among women, established parents had greater intentions than new- and non-parents, F(2) = 5.33, p = .01. Among both men and women during the first 6-months post-delivery, new-parents experienced decreased PBC, whereas established parents experienced increased PBC. Overall, affective attitudes were the strongest predictor of intentions for men (β = 0.55, p < .001) and women (β = 0.38, p < .01). PBC predicted changes in fruit and vegetable consumption for men (β = 0.45, p = .02), and changes in fat consumption for men (β = -0.25, p = .03) and women (β = -.24, p < .05), regardless of parent status. The transition to parenthood for new and established parents may impact motivation for healthy eating, especially PBC within the framework of TPB. However, regardless of parental status, affective attitudes and PBC are critical antecedents of
2013-01-01
Background Transitioning to parenthood is a major life event that may impact parents’ personal lifestyles, yet there is an absence of theory-based research examining the impact of parenthood on motives for dietary behaviour. As a result, we are unaware of the social cognitive variables that predict eating behaviour among those transitioning to parenthood. The purpose of the study was to examine eating behaviour motives across 12 months within the framework of the theory of planned behavior (TPB) and compare these across groups of new parents, non-parents, and established parents. Methods Non-parents (n = 92), new parents (n = 135), and established parents (n = 71) completed TPB questionnaires assessing attitudes, subjective norms, perceived behavioral control (PBC), and intentions and three day food records at baseline, and 6- and 12-months post-delivery (for parents) and 6- and 12-months post-baseline (for non-parents). Results Repeated measures ANOVAs revealed that among men, new- and established-parents had greater intentions to eat healthy compared to non-parents, F(2) = 3.59, p = .03. Among women, established parents had greater intentions than new- and non-parents, F(2) = 5.33, p = .01. Among both men and women during the first 6-months post-delivery, new-parents experienced decreased PBC, whereas established parents experienced increased PBC. Overall, affective attitudes were the strongest predictor of intentions for men (β = 0.55, p < .001) and women (β = 0.38, p < .01). PBC predicted changes in fruit and vegetable consumption for men (β = 0.45, p = .02), and changes in fat consumption for men (β = −0.25, p = .03) and women (β = −.24, p < .05), regardless of parent status. Conclusion The transition to parenthood for new and established parents may impact motivation for healthy eating, especially PBC within the framework of TPB. However, regardless of parental status, affective
Goodpaster, Jason D; Manby, Frederick R; Miller, Thomas F
2012-01-01
Density functional theory (DFT) embedding provides a formally exact framework for interfacing correlated wave-function theory (WFT) methods with lower-level descriptions of electronic structure. Here, we report techniques to improve the accuracy and stability of WFT-in-DFT embedding calculations. In particular, we develop spin-dependent embedding potentials in both restricted and unrestricted orbital formulations to enable WFT-in-DFT embedding for open-shell systems, and we develop an orbital-occupation-freezing technique to improve the convergence of optimized effective potential (OEP) calculations that arise in the evaluation of the embedding potential. The new techniques are demonstrated in applications to the van-der-Waals-bound ethylene-propylene dimer and to the hexaaquairon(II) transition-metal cation. Calculation of the dissociation curve for the ethylene-propylene dimer reveals that WFT-in-DFT embedding reproduces full CCSD(T) energies to within 0.1 kcal/mol at all distances, eliminating errors in th...
Phase-Transition Theory of Kerr Black Holes in Electromagnetic Field
Liao, Yi; Wu, Jian-Sheng
2016-01-01
For a Kerr black hole (KBH) with spin $J$ and mass $M$ in a steady electromagnetic field, a special Wald vacuum solution (WVS) has been found in the case of no-source uniform field. For WVS, the Meissner effect (ME) occurs only in the the extreme KBH where $M^2/J=1$, in this case, the magnetic field is totally excluded from the event horizon (EH) of KBH. However, WVS does not consider the Hawking radiation (HR) but treats KBH as an absolutely black body. If HR is added , researchers believe that the condition is not so restricted and it is possible for ME to occur in less extreme case. How less is the "less extreme case"? This paper tries to answer this question. Since the Hawking temperature $T_H$ of KBH defined by HR is proportional to the surface gravity $\\kappa$ at the EH, this question is actually about the so-called existence/non-existence of ME (ME/NME) or superconducting phase transition. In this paper, we study the connection between the superconductivity of KBH-EH and the existence of Weyl Fermion (...
Komninos, Yannis; Mercouris, Theodoros; Nicolaides, Cleanthes A.
2017-01-01
The present study examines the mathematical properties of the free-free ( f - f) matrix elements of the full electric field operator, O E (κ, r̅), of the multipolar Hamiltonian. κ is the photon wavenumber. Special methods are developed and applied for their computation, for the general case where the scattering wavefunctions are calculated numerically in the potential of the term-dependent ( N - 1) electron core, and are energy-normalized. It is found that, on the energy axis, the f - f matrix elements of O E (κ, r̅) have singularities of first order, i.e., as ɛ' → ɛ, they behave as ( ɛ - ɛ')-1. The numerical applications are for f - f transitions in hydrogen and neon, obeying electric dipole and quadrupole selection rules. In the limit κ = 0, O E (κ, r̅) reduces to the length form of the electric dipole approximation (EDA). It is found that the results for the EDA agree with those of O E (κ, r̅), with the exception of a wave-number region k' = k ± κ about the point k' = k.
Fyodorov, Yan V; Keating, Jonathan P
2014-01-28
We argue that the freezing transition scenario, previously conjectured to occur in the statistical mechanics of 1/f-noise random energy models, governs, after reinterpretation, the value distribution of the maximum of the modulus of the characteristic polynomials pN(θ) of large N×N random unitary (circular unitary ensemble) matrices UN; i.e. the extreme value statistics of pN(θ) when N → ∞. In addition, we argue that it leads to multi-fractal-like behaviour in the total length μN(x) of the intervals in which |pN(θ)|>N(x), x>0, in the same limit. We speculate that our results extend to the large values taken by the Riemann zeta function ζ(s) over stretches of the critical line s = 1/2 + it of given constant length and present the results of numerical computations of the large values of ζ(1/2 + it). Our main purpose is to draw attention to the unexpected connections between these different extreme value problems.
Freezing transitions and extreme values: random matrix theory, and disordered landscapes
Fyodorov, Yan V.; Keating, Jonathan P.
2014-01-01
We argue that the freezing transition scenario, previously conjectured to occur in the statistical mechanics of 1/f-noise random energy models, governs, after reinterpretation, the value distribution of the maximum of the modulus of the characteristic polynomials pN(θ) of large N×N random unitary (circular unitary ensemble) matrices UN; i.e. the extreme value statistics of pN(θ) when . In addition, we argue that it leads to multi-fractal-like behaviour in the total length μN(x) of the intervals in which |pN(θ)|>Nx,x>0, in the same limit. We speculate that our results extend to the large values taken by the Riemann zeta function ζ(s) over stretches of the critical line of given constant length and present the results of numerical computations of the large values of ). Our main purpose is to draw attention to the unexpected connections between these different extreme value problems. PMID:24344336
An exacting transition probability measurement - a direct test of atomic many-body theories
Dutta, T; Yum, D; Rebhi, R; Mukherjee, M
2016-01-01
A new protocol for measuring the branching fraction of hydrogenic atoms with only statistically limited uncertainty is proposed and demonstrated for the decay of the P$_{3/2}$ level of the barium ion, with precision below $0.5\\%$. Heavy hydrogenic atoms like the barium ion are test beds for fundamental physics such as atomic parity violation and they also hold the key to understanding nucleo-synthesis in stars. To draw definitive conclusion about possible physics beyond the standard model by measuring atomic parity violation in the barium ion it is necessary to measure the dipole transition probabilities of low-lying excited states with precision better than $1\\%$. Furthermore, enhancing our understanding of the $\\it{barium-puzzle}$ in barium stars requires branching fraction data for proper modelling of nucleo-synthesis. Our measurements are the first to provide a direct test of quantum many-body calculations on the barium ion with precision below one percent and more importantly with no known systematic unc...
Chin, Alex W; Prior, Javier; Huelga, Susana F; Plenio, Martin B
2011-10-14
The sub-Ohmic spin-boson model possesses a quantum phase transition at zero temperature between a localized and a delocalized phase, whose properties have so far only been extracted by numerical approaches. Here we present an extension of the Silbey-Harris variational polaron ansatz which allows us to develop an analytical theory which correctly describes a continuous transition with mean-field exponents for 0transition.
Imamura, Yutaka; Kamiya, Muneaki; Nakajima, Takahito
2016-03-01
We study spin-forbidden transitions of Os polypyridyl sensitizers by two-component relativistic time-dependent density functional theory with the spin-orbit interaction based on Tamm-Dancoff approximation. The absorption spectra, including spin-forbidden-transition peaks, for the Os complexes are reasonably reproduced in comparison with the experimental ones. The extension of the conjugated lengths in the Os complexes is investigated and found to be effective to enhance photo absorption for spin-allowed transitions as well as spin-forbidden ones. This study provides fruitful information for a design of new dyes in terms of conjugation lengths.
Two centuries of demographic change in Canada
Directory of Open Access Journals (Sweden)
Barry Edmonston
2014-03-01
Full Text Available One key aspect of the demographic transition—the shift from high mortality and high fertility to low mortality and low fertility is a major change in the population’s age distribution from a pyramid-shaped young age structure to a pillar-shaped old age structure. This paper discusses two demographic processes affected by changes in age structure. First, there are effects on vital rates, with important differences in the observed crude rates and the implied intrinsic vital rates. Second, changes in age structure influence population momentum. More recently, demographers have noted that older age distributions associated with fertility levels below replacement have negative population momentum. Although the demographic transition has been well-described for many countries, demographers have seldom analyzed intrinsic vital rates and population momentum over time, which are dynamic processes affected by changes in the population age structure and which, in turn, influence future changes in population growth and size. This paper uses new data and methods to analyze intrinsic vital rates and population momentum across two centuries of demographic change in Canada
Li, Yi
It is of great scientific significance to study the complex systems of agents with adaptive strategies competing for resources. In many of such systems in social and biological environments, agents succeed by making innovative choices. In this thesis, we model this behavior by presenting the results and analysis of a class of games in which heterogeneous agents are rewarded for being in a minority group. Each agent possesses a number of fixed strategies, each of which takes publicly available information as input to predict next group. Commonly known as the minority game, this simple model manifests a maladaptive, informationally efficient phase in which the system performs poorly at generating resources and an inefficient phase in which there is an emergent cooperation among the agents, and the system more effectively generates resources. The best emergent coordination is achieved at the phase transition, which occurs when z, the ratio of the dimension of the strategy space to the number of agents, is about 0.34. This model also has similar properties to a spin glass system thus statistical mechanics methods were employed to provide analytical results. The phase structure persists under variations such as variable payoff schemes and evolutionary mechanisms. Agents in real life are subject to local connectivity and incomplete information. A framework based on bi-graph was proposed to model these factors. In the context of economics, we proposed a stock market model incorporating delayed majority dynamics and agents holding heterogeneous expectations. We found that for a range of parameter settings, minority dynamics are dynamically induced, effectively reducing market volatility. Finally, we introduce a version of the minority game played by human participants. We observed emergent coordination of players' choices leading to increased average reward. Furthermore, players with the simplest strategies reap the most wealth.
Aquilanti, Vincenzo; Coutinho, Nayara Dantas; Carvalho-Silva, Valter Henrique
2017-04-28
This article surveys the empirical information which originated both by laboratory experiments and by computational simulations, and expands previous understanding of the rates of chemical processes in the low-temperature range, where deviations from linearity of Arrhenius plots were revealed. The phenomenological two-parameter Arrhenius equation requires improvement for applications where interpolation or extrapolations are demanded in various areas of modern science. Based on Tolman's theorem, the dependence of the reciprocal of the apparent activation energy as a function of reciprocal absolute temperature permits the introduction of a deviation parameter d covering uniformly a variety of rate processes, from those where quantum mechanical tunnelling is significant and d 0, corresponding to the Pareto-Tsallis statistical weights: these generalize the Boltzmann-Gibbs weight, which is recovered for d = 0. It is shown here how the weights arise, relaxing the thermodynamic equilibrium limit, either for a binomial distribution if d > 0 or for a negative binomial distribution if d theory for chemical kinetics including quantum mechanical tunnelling, and for case (iii) to the stereodirectional specificity of the dynamics of reactions strongly hindered by the increase of temperature.This article is part of the themed issue 'Theoretical and computational studies of non-equilibrium and non-statistical dynamics in the gas phase, in the condensed phase and at interfaces'. © 2017 The Author(s).
Energy Technology Data Exchange (ETDEWEB)
Nakata, Hidehiko [Waseda Univ., Tokyo (Japan). Dept. of Physics; Tachibana, Takahiro; Yamada, Masami
1997-03-01
Recently the gross theory of nuclear {beta}-decay was refined for odd-odd nuclei. In this refinement, the effect of the selection rule of {beta}-transitions from the ground states of odd-odd nuclei to those of even-even nuclei was taken into account based on a statistical consideration. The transitions to the first 2{sup +} excited states in even-even nuclei were also taken into account according to the selection rule approximately. In that study, it was found that the transitions between 1{sup -} ground states of the odd-odd nuclei and 0{sup +} ground states of even-even nuclei, belonging to the first-forbidden transitions of rank 1, are strongly hindered. A reduction factor was introduced for the transitions to the ground states of even-even nuclei to take into account this hindrance. It was also found that the strength functions of the Gamow-Teller transitions obtained from the conventional gross theory are underestimated by a factor of about 3. In order to improve this underestimation, the Lorentz-type function was adopted for the one-particle strength function in the model instead of the hyperbolic-secant-type function. In the present study we have newly analyzed the experimental ft-values of odd-A nuclei, and found that the first-forbidden transitions of rank 1 are also considerably hindered between the ground states. Following the above refinement we have calculated the {beta}-ray spectra of some odd-odd short-lived fission products with the use of the refined gross theory. These results are compared not only with the experiments by Rudstam et al. but also with the conventional gross theory. (author)
The Gender and Intergenerational Consequences of the Demographic Dividend
2009-01-01
The demographic transition changes the age composition of a population, potentially affecting resource allocation at the household level and exerting general equilibrium effects at the aggregate level. If age profiles of income, consumption, and savings were stable and estimable for the entire population, they might imply how the demographic transition would affect national savings rates, but there is little agreement on the impact of age composition. These age profiles differ by gender and a...
Demographic Change and Transport
DEFF Research Database (Denmark)
Haustein, Sonja; Siren, Anu Kristiina; Framke, Elisabeth
This report is the literature review on demographic changes and transport of Work Package 1 of the EU project CONSOL, “CONcerns and SOLutions – Road Safety in the Ageing Societies” (contract period: 2011-2013). The report is a state-of-the art report that combines current knowledge with new findi...
Beacom, Amy Maureen
2013-01-01
Today, women comprise nearly half the U.S. workforce and outnumber men in many previously male-dominated fields. This seismic cultural and demographic shift has dramatically impacted organizations. The most obvious impact is the presence of, and dependence on, increased numbers of women employees throughout organizations. Retention of talented…
Starr, Francis W.; Douglas, Jack F.; Sastry, Srikanth
2013-03-01
We carefully examine common measures of dynamical heterogeneity for a model polymer melt and test how these scales compare with those hypothesized by the Adam and Gibbs (AG) and random first-order transition (RFOT) theories of relaxation in glass-forming liquids. To this end, we first analyze clusters of highly mobile particles, the string-like collective motion of these mobile particles, and clusters of relative low mobility. We show that the time scale of the high-mobility clusters and strings is associated with a diffusive time scale, while the low-mobility particles' time scale relates to a structural relaxation time. The difference of the characteristic times for the high- and low-mobility particles naturally explains the well-known decoupling of diffusion and structural relaxation time scales. Despite the inherent difference of dynamics between high- and low-mobility particles, we find a high degree of similarity in the geometrical structure of these particle clusters. In particular, we show that the fractal dimensions of these clusters are consistent with those of swollen branched polymers or branched polymers with screened excluded-volume interactions, corresponding to lattice animals and percolation clusters, respectively. In contrast, the fractal dimension of the strings crosses over from that of self-avoiding walks for small strings, to simple random walks for longer, more strongly interacting, strings, corresponding to flexible polymers with screened excluded-volume interactions. We examine the appropriateness of identifying the size scales of either mobile particle clusters or strings with the size of cooperatively rearranging regions (CRR) in the AG and RFOT theories. We find that the string size appears to be the most consistent measure of CRR for both the AG and RFOT models. Identifying strings or clusters with the "mosaic" length of the RFOT model relaxes the conventional assumption that the "entropic droplets" are compact. We also confirm the
Energy Technology Data Exchange (ETDEWEB)
Romero, F J; Gallardo, M C; Del Cerro, J [Departamento de Fisica de la Materia Condensada, Instituto Mixto de Ciencia de Materiales CSIC-Universidad de Sevilla, Apartado 1065, 41080 Sevilla (Spain)], E-mail: fjromero@us.es
2009-04-15
The influence of electric fields lower than the critical field in the ferroelectric phase transition in deuterated triglycine selenate has been studied by means of thermal and dielectric properties. The latent heat, specific heat and dielectric constant have been measured and compared to the theoretical expectations from the Landau theory under an electric field. A full agreement has been found on cooling experiments.
Energy Technology Data Exchange (ETDEWEB)
Shamim, Md; Harbola, Manoj K, E-mail: sami@iitk.ac.i, E-mail: mkh@iitk.ac.i [Department of Physics, Indian Institute of Technology, Kanpur 208 016 (India)
2010-11-14
Transition energies of a new class of excited states (two-gap systems) of various atoms are calculated in time-independent density functional formalism by using a recently proposed local density approximation exchange energy functional for excited states. It is shown that the excitation energies calculated with this functional compare well with those calculated with exact exchange theories.
SELECTED DETERMINANTS OF DEMOGRAPHIC SAFETY
Directory of Open Access Journals (Sweden)
Stanisława Ostasiewicz
2016-09-01
Full Text Available The article presents, in a simplifi ed manner, selected theories of population to explain the current trends of population development in Poland and throughout the world. The aim of the article is to present the demographic threats that have emerged in the last eighty years. Prognosticated age structures have also been predicted. Signifi cant diff erences between the structure of the population now and the future have been indicated, particularly regarding the ageing of the population. Against the background of global transformations analyzes of changes in Poland have been conducted. The comparison shows that changes in Poland are highly analogous to transformations around the world, such as declining birth rates and increasing life expectancy. These changes cause ageing of the population, which could result in the collapse of the functioning of the labor market and the pension system as it currently exists.
Jang, Seogjoo; Voth, Gregory A
2017-05-07
Despite the fact that quantum mechanical principles do not allow the establishment of an exact quantum analogue of the classical transition state theory (TST), the development of a quantum TST (QTST) with a proper dynamical justification, while recovering the TST in the classical limit, has been a long standing theoretical challenge in chemical physics. One of the most recent efforts of this kind was put forth by Hele and Althorpe (HA) [J. Chem. Phys. 138, 084108 (2013)], which can be specified for any cyclically invariant dividing surface defined in the space of the imaginary time path integral. The present work revisits the issue of the non-uniqueness of QTST and provides a detailed theoretical analysis of HA-QTST for a general class of such path integral dividing surfaces. While we confirm that HA-QTST reproduces the result based on the ring polymer molecular dynamics (RPMD) rate theory for dividing surfaces containing only a quadratic form of low frequency Fourier modes, we find that it produces different results for those containing higher frequency imaginary time paths which accommodate greater quantum fluctuations. This result confirms the assessment made in our previous work [Jang and Voth, J. Chem. Phys. 144, 084110 (2016)] that HA-QTST does not provide a derivation of RPMD-TST in general and points to a new ambiguity of HA-QTST with respect to its justification for general cyclically invariant dividing surfaces defined in the space of imaginary time path integrals. Our analysis also offers new insights into similar path integral based QTST approaches.
Energy Technology Data Exchange (ETDEWEB)
Burrola-Gándara, L. A., E-mail: andres.burrola@gmail.com; Santillan-Rodriguez, C. R.; Rivera-Gomez, F. J.; Saenz-Hernandez, R. J.; Botello-Zubiate, M. E.; Matutes-Aquino, J. A. [Departamento de Física de Materiales, Centro de Investigación en Materiales Avanzados, S.C., Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua 31109 (Mexico)
2015-05-07
Magnetocaloric materials with second order phase transition near the Curie temperature can be described by critical phenomena theory. In this theory, scaling, universality, and renormalization are key concepts from which several phase transition order criteria are derived. In this work, the rescaled universal curve, Banerjee and mean field theory criteria were used to make a comparison for several magnetocaloric materials including pure Gd, SmCo{sub 1.8}Fe{sub 0.2}, MnFeP{sub 0.46}As{sub 0.54}, and La{sub 0.7}Ca{sub 0.15}Sr{sub 0.15}MnO{sub 3}. Pure Gd, SmCo{sub 1.8}Fe{sub 0.2}, and La{sub 0.7}Ca{sub 0.15}Sr{sub 0.15}MnO{sub 3} present a collapse of the rescaled magnetic entropy change curves into a universal curve, which indicates a second order phase transition; applying Banerjee criterion to H/σ vs σ{sup 2} Arrot plots and the mean field theory relation |ΔS{sub M}| ∝ (μ{sub 0}H/T{sub c}){sup 2/3} for the same materials also determines a second order phase transition. However, in the MnFeP{sub 0.46}As{sub 0.54} sample, the Banerjee criterion applied to the H/σ vs σ{sup 2} Arrot plot indicates a first order magnetic phase transition, while the mean field theory prediction for a second order phase transition, |ΔS{sub M}| ∝ (μ{sub 0}H/T{sub c}){sup 2/3}, describes a second order behavior. Also, a mixture of first and second order behavior was indicated by the rescaled universal curve criterion. The diverse results obtained for each criterion in MnFeP{sub 0.46}As{sub 0.54} are apparently related to the magnetoelastic effect and to the simultaneous presence of weak and strong magnetism in Fe (3f) and Mn (3g) alternate atomic layers, respectively. The simultaneous application of the universal curve, the Banerjee and the mean field theory criteria has allowed a better understanding about the nature of the order of the phase transitions in different magnetocaloric materials.
Escudero, Daniel; Thiel, Walter
2014-05-21
We report an assessment of the performance of density functional theory-based multireference configuration interaction (DFT/MRCI) calculations for a set of 3d- and 4d-transition metal (TM) complexes. The DFT/MRCI results are compared to published reference data from reliable high-level multi-configurational ab initio studies. The assessment covers the relative energies of different ground-state minima of the highly correlated CrF6 complex, the singlet and triplet electronically excited states of seven typical TM complexes (MnO4(-), Cr(CO)6, [Fe(CN)6](4-), four larger Fe and Ru complexes), and the corresponding electronic spectra (vertical excitation energies and oscillator strengths). It includes comparisons with results from different flavors of time-dependent DFT (TD-DFT) calculations using pure, hybrid, and long-range corrected functionals. The DFT/MRCI method is found to be superior to the tested TD-DFT approaches and is thus recommended for exploring the excited-state properties of TM complexes.
Energy Technology Data Exchange (ETDEWEB)
Moskvin, A S [Ural State University, Ekaterinburg, 620083 (Russian Federation); Philipiev, M P [Ural State University, Ekaterinburg, 620083 (Russian Federation); Solovyova, O E [Ural State University, Ekaterinburg, 620083 (Russian Federation); Markhasin, V S [Institute of Immunology and Physiology, Ekaterinburg, 620219 (Russian Federation)
2005-01-01
Theory of photo-induced phase transitions has been adapted to describe the cooperative dynamics of the lattice of ryanodine receptors/channels (RyR) in cardiac muscle which regulate the release of the intracellular activator calcium from calcium stores in the sarcoplasmic reticulum (SR) by a process of Ca{sup 2+}-induced Ca{sup 2+} release (CICR). We introduce two main degrees of freedom for RyR channel, fast electronic and slow conformational ones. The RyR lattice response to the L-type channel triggering evolves due to a nucleation process with a step-by-step domino-like opening of RyR channels. Typical mode of RyR lattice functioning in a CICR process implies the fractional release with a robust termination due to the depletion of SR with a respective change in effective conformational strain. The SR overload leads to an unconventional auto-oscillation regime with a spontaneous calcium release. The model is believed to consistently describe the main features of CICR, that is its gradedness, coupled gating, irreversibility, inactivation/adaptation, and spark termination.
Energy Technology Data Exchange (ETDEWEB)
Suleymanov, Mais [CIIT, Islamabad (Pakistan); Shahaliev, Ehtiram [HEPL, JINR, Dubna (Russian Federation)
2009-07-01
Over the last 25 years a lot of efforts have been made to search for new phases of strongly interacting matter. Heavy ion collisions are of great importance since they open a way to reproduce these phases in the Earth laboratory. But in this case the volume of information increases sharply as well as the background information. A method was introduced a method on the basic of Random Matrix Theory to study the fluctuations of neutron resonances in compound nuclei which doesn't depend on the background of measurements. To analyze the energetic levels of compound nuclei the function of distances between two energetic levels p(s{sub i}) is defined as the general distributions for probability of all kinds of ensembles. At values of the index of universality {nu}=0 it will change to Poisson type distributions pointing to absence of any correlations in the system and at the values of {nu}=1 it will change to Wigner type behavior directing to some correlation in the studying ensemble. We discuss that the experimental study of the behavior of p(s{sub i}) distribution for secondary particles could give a signal on the phase transitions.
Directory of Open Access Journals (Sweden)
A. K. Aggarwal
2014-01-01
Full Text Available The objective of this paper is to provide guidance for the design of the thick-walled cylinder made up of transversely isotropic material so that collapse of cylinder due to influence of internal and external pressure can be avoided. The concept of transition theory based on Lebesgue strain measure has been used to simplify the constitutive equations. Results have been analyzed theoretically and discussed numerically. From this analysis, it has been concluded that, under the influence of internal and external pressure, circular cylinder made up of transversely isotropic material (beryl is on the safer side of the design as compared to the cylinders made up of isotropic material (steel. This is because of the reason that percentage increase in effective pressure required for initial yielding to become fully plastic is high for beryl as compared to steel which leads to the idea of “stress saving” that reduces the possibility of collapse of thick-walled cylinder due to internal and external pressure.
A Statistical Assessment of Demographic Bonus towards Poverty Alleviation
Directory of Open Access Journals (Sweden)
Jamal Abdul Nasir
2011-09-01
Full Text Available The shift of birth and death rates from high to low level in any population is referred as demographic transition. Mechanically, the transition of a society creates more working member of its own population commonly called demographic bonus. This articleempirically explores the realistic soundness of demographic bonus in reducing the poverty level of the society. Three contrasting regions namely Eastern Asia, Central America and Oceania were selected for analytical purposes. The findings indicate that Eastern Asia and Oceania are currently facing the end of their transition whereas theCentral America is lagged behind in transition. Central America due to last runner in transition race is the sustained recipient of its own demographic bonus by the year 2030.On the basis of three mechanisms namely: labour supply, savings and human capital, the Eastern Asian region is found to be successful beneficiary of its own demographic gift which concludes that many million people have escaped from poverty. Under the right policy environment on the above three mechanisms, Eastern Asia experience indicates the realistic contribution of demographic bonus to reduce poverty.
How attitude certainty tempers the effects of faultlines in demographically diverse teams
Grow, Andre; Flache, Andreas
2011-01-01
Lau and Murnighan's faultline theory suggests that strong demographic faultlines can undermine cohesion in work teams. A strong faultline splits a team into internally homogeneous but mutually dissimilar subgroups based on demographic characteristics. Social influence processes within these subgroup
How attitude certainty tempers the effects of faultlines in demographically diverse teams
Grow, Andre; Flache, Andreas
2011-01-01
Lau and Murnighan's faultline theory suggests that strong demographic faultlines can undermine cohesion in work teams. A strong faultline splits a team into internally homogeneous but mutually dissimilar subgroups based on demographic characteristics. Social influence processes within these subgroup
Demographic and affective covariates of pain.
Garron, D C; Leavitt, F
1979-11-01
Relationships of four demographic variables and five affective variables to eight attributes of low back pain were investigated in 251 patients by stepwise, multivariate analysis. The demographic variables are age, sex, race, and education. The affective variables are state anxiety, trait anxiety anxiety, hostility, and depression. Seven of the pain variables are from the factorially derived Low Back Pain Questionnaire. The eighth pain variable is a self-estimate of intensity. Relationships among demographic and pain variables are small and unsystematic. Hostility has a small, systematically inverse relation to pain variables, supporting theories relating low back pain to inhibition of anger. Anxiety has a small positive relationship, and depression has no relationship to pain variables. In general, the small relationships indicate that the Low Back Pain Questionnaire provides descriptions of pain that are not confounded by social characteristics or current emotional states of patients.