Towards Transition Theory

NARCIS (Netherlands)

J. de Haan (Hans)

2010-01-01

textabstractThis thesis is a treatise on a theory for societal transitions: pillar theory. Societal transitions are complex processes taking place in complex systems, large-scale, long-term processes in which societal systems radically change the way they are composed and function. Since we all are

Turkey’s Epidemiological and Demographic Transitions: 1931-2013

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Coşkun Bakar

2017-08-01

Full Text Available Background: 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. Aims: To discuss the epidemiological and demographic transitions in Turkey, using demographic, educational and urbanization data in our present study. Study Design: A descriptive archive study. Methods: 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. Results: 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. Conclusion: 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

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.

Situation-specific theories from the middle-range transitions theory.

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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.

Policy Implications of the Next World Demographic Transition

OpenAIRE

Harbison, Sarah F.; Robinson, Warren C.

2002-01-01

Although the world demographic transition from high to low fertility appears to be nearing its completion, observed in perspective, this is the latest in a series of such transitions stretching back into prehistory. A stable new equilibrium is far from inevitable; indeed, it is unlikely. Many countries are experiencing below‐replacement‐level fertility, and this trend is spreading. Couples are now able to choose their family size, free of the traditional pressures to bear children that was ch...

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.

Lifetime reproduction and the second demographic transition: Stochasticity and individual variation

NARCIS (Netherlands)

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

Russian Federation : From the first to second demographic transition

NARCIS (Netherlands)

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

The demographic transition influences variance in fitness and selection on height and BMI in rural Gambia.

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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.

Phase transitions in nonequilibrium traffic theory

Energy Technology Data Exchange (ETDEWEB)

Zhang, H.M.

2000-02-01

This paper uses the center difference scheme of Lax-Friedrichs to numerically solve a newly developed continuum traffic flow theory and the kinematic theory of Lighthill and Whitham, and Richards, and it studies the flow-concentration phase transitions in flow containing both shock and rarefaction waves. A homogeneous road with finite length was modeled by both theories. Numerical simulations show that both theories yield nearly identical results for two representative Riemann problems--one has a shock solution and the other a rarefaction wave solution. Their phase transition curves, however, are different: those derived from the new theory have two branches--one for acceleration flow and one for deceleration flow, whereas those derived from the LWR theory comprise a single curve--the equilibrium curve. The phase transition curves in the shock case agree well with certain experimental observations but disagree with others. This disagreement may be resolved by studying transitions among nonequilibrium states, which awaits further development of a more accurate finite difference approximation of the nonequilibrium theory.

Topological transitions in the theory of spacetime

International Nuclear Information System (INIS)

Konstantinov, M.Y.; Melnikov, V.N.

1986-01-01

Results of a realisation of the topological transitions hypothesis are presented. The basic difficulties in the construction of quantum topological transition theory are connected with a necessity to introduce a new non-local interaction defined on a space of topological states. So the general method of construction and study of topological transitions classical models is formulated as a necessary step towards a corresponding quantum description. Their local properties, including an asymptotic behaviour in the neighbourhood of the transition, are studied and applications to problems of gravitation and cosmology are given. The method used is shown to lead to a scalar-tensor theory of topological transitions. Different variants of this theory and its main features are discussed. (author)

Variational transition state theory

International Nuclear Information System (INIS)

Truhlar, D.G.

1986-01-01

This project is concerned with the development and applications of generalized transition state theory and multidimensional tunneling approximations to chemical reaction rates. They have developed and implemented several practical versions of variational transition state theory (VTST), namely canonical variational theory (CVT), improved canonical variational theory (ICVT), and microcanonical variational theory (μVT). They have also developed and implemented several accurate multidimensional semiclassical tunneling approximations, the most accurate of which are the small-curvature semiclassical adiabatic (SCSA), large-curvature version-3 (LC3), and least-action (LA) approximations. They have applied the methods to thermal rate constants, using transmission coefficients based on ground-state tunneling, and they have also presented and applied adiabatic and diabatic extensions to calculated rate constants for vibrationally excited reactants. Their general goal is to develop accurate methods for calculating chemical reaction rate constants that remain practical even for reasonably complicated molecules. The approximations mentioned above yield rate constants for systems whose potential energy surface is known or assumed. Thus a second, equally important aspect of their work is the determination or modeling, semi-empirically and/or from electronic structure calculations, of potential energy surfaces

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.

Partner relationships in the Netherlands: new manifestations of the Second Demographic Transition

NARCIS (Netherlands)

Latten, J.J.; Mulder, C.H.

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

Partner relationships in the Netherlands : New manifestations of the Second Demographic Transition

NARCIS (Netherlands)

Latten, Jan J.; Mulder, Clara H.

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

Demographic, epidemiological, and health transitions: are they relevant to population health patterns in Africa?

Science.gov (United States)

Kuate Defo, Barthélémy

2014-01-01

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. 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. 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 in life expectancy from the

Gifted Students in Transition: A Grounded Theory Study

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Meadows, Jodi J.

2017-01-01

Gifted students in transition to college may be at risk for underachievement, difficult transition, or even attrition. Giftedness by itself is not always sufficient for academic success in college. The purpose of this grounded theory study was to construct a theory regarding the process of transition to college for high-achieving gifted high…

Demographic implications of socioeconomic transition among the tribal populations of Manipur, India.

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Hemam, N S; Reddy, B M

1998-06-01

The demographic implications of socioeconomic transition are studied among the three subsistence categories of the Gangte, a little known tribe from northeast India. Reproductive histories of 444 ever-married women and other data on the 343 households from which these women were drawn were collected from 11 villages representing the 3 transitional groups. A trend of increasing household income and literacy of couples was observed from shifting cultivators to settled agriculturists to the town-dwelling Gangte. The effect of socioeconomic transition is also seen in the constriction at the base of the age-sex pyramid of the town dwellers compared with the other subsistence categories, suggesting a relatively lower proportion of children in the 0-5-year-old age group. Although exogamy is practiced among all the subsistence categories, a considerably higher percentage of admixture with non-Gangte is observed among the town dwellers compared with the others. Overall infant and child mortality among the Gangte is low. However, variation exists among the three subsistence groups in the sense that a considerable reduction is seen from the traditional shifting cultivators to the urbanized town dwellers, reflecting better socioeconomic conditions and greater awareness and accessibility of the town dwellers to public health amenities. No consistent or perceptible trend is evident in mean number of live births. The genetic implications of this demographic transition are reflected in Crow's indexes of selection.

Demographic, epidemiological, and health transitions: are they relevant to population health patterns in Africa?

Directory of Open Access Journals (Sweden)

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

Demographic, epidemiological, and health transitions: are they relevant to population health patterns in Africa?

Science.gov (United States)

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

Scaling theory and the classification of phase transitions

International Nuclear Information System (INIS)

Hilfer, R.

1992-01-01

In this paper, the recent classification theory for phase transitions and its relation with the foundations of statistical physics is reviewed. First it is outlined how Ehrenfests classification scheme can be generalized into a general thermodynamic classification theory for phase transitions. The classification theory implies scaling and multiscaling thereby eliminating the need to postulate the scaling hypothesis as a fourth law of thermodynamics. The new classification has also led to the discovery and distinction of nonequilibrium transitions within equilibrium statistical physics. Nonequilibrium phase transitions are distinguished from equilibrium transitions by orders less than unity and by the fact the equilibrium thermodynamics and statistical mechanics become inapplicable at the critical point. The latter fact requires a change in the Gibbs assumption underlying the canonical and grandcanonical ensembles in order to recover the thermodynamic description in the critical limit

Towards the theory of the electroweak phase transition

International Nuclear Information System (INIS)

Dine, M.; Leigh, R.G.; Huet, P.; Linde, A.; Linde, D.

1992-01-01

We investigate various problems related to the theory of the electroweak phase transition. This includes determination of the nature of the phase transition, discussion of the possible role of the higher-order radiative corrections, and the theory of the formation and evolution of bubbles of the new phase. We show, in particular, that no dangerous linear terms in the scalar field φ appear in the expression for the effective potential. We have found that, for the Higgs-boson mass smaller than the masses of W and Z bosons, the phase transition is of the first order. However, its strength is approximately 2/3 times less than what follows from the one-loop approximation. The phase transition occurs due to production and expansion of critical bubbles. Subcritical bubbles may be important only if the phase transition is very weakly first order. A general analytic expression for the probability of the bubble formation is obtained, which may be used for study of tunneling in a wide class of theories. The bubble-wall velocity depends on many factors, including the ratio of the mean free path of the particles to the thickness of the wall. Thin walls in the electroweak theory have a nonrelativistic velocity, whereas thick walls may be relativistic. A decrease of the cubic term by the factor 2/3 rules our baryogenesis in the minimal version of the electroweak theory. Even though we concentrate in this paper on the phase transition in this theory, most of our results can be applied to more general models as well, where baryogenesis is possible

A Quantum Version of Wigner's Transition State Theory

NARCIS (Netherlands)

Schubert, R.; Waalkens, H.; Wiggins, S.

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

Future scenarios for energy consumption and carbon emissions due to demographic transitions in Chinese households

Science.gov (United States)

Yu, Biying; Wei, Yi-Ming; Kei, Gomi; Matsuoka, Yuzuru

2018-02-01

Population dynamics has been acknowledged as a key concern for projecting future emissions, partly because of the huge uncertainties related to human behaviour. However, the heterogeneous shifts of human behaviour in the process of demographic transition are not well explored when scrutinizing the impacts of population dynamics on carbon emissions. Here, we expand the existing population-economy-environment analytical structure to address the above limitations by representing the trend of demographic transitions to small-family and ageing society. We specifically accommodate for inter- and intra-life-stage variations in time allocation and consumption in the population rather than assuming a representative household, and take a less developed province, Sichuan, in China as the empirical context. Our results show that the demographic shift to small and ageing households will boost energy consumption and carbon emissions, driven by the joint variations in time-use and consumption patterns. Furthermore, biased pictures of changing emissions will emerge if the time effect is disregarded.

The neolithic demographic transition in Europe: correlation with juvenility index supports interpretation of the summed calibrated radiocarbon date probability distribution (SCDPD as a valid demographic proxy.

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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.

Demographic transition in sub-Saharan Africa: how big will the economic dividend be?

Science.gov (United States)

Eastwood, Robert; Lipton, Michael

2011-03-01

In mid-demographic-transition, many Asian countries enjoyed a large demographic 'dividend': extra economic growth owing to falling dependant/workforce ratios, or slower natural increase, or both. We estimate the dividend, 1985-2025, in sub-Saharan Africa and its populous countries. Dependency and natural increase peaked around 1985, 20 years after Asia. The UN projects an acceleration of the subsequent slow falls but disregards slowish declines in young-age mortality and thus, we argue, overestimates future fertility decline. Even if one accepts their projection, arithmetical and econometric evidence suggests an annual, if not total, dividend well below Asia's. The dividend arises more from falling dependency than reduced natural increase, and could be increased by accelerating the fertility decline (e.g., by reducing young-age mortality) or by employing a larger workforce productively. Any dividend from transition apart, low saving in much of Africa (unlike Asia) means that, given likely natural increase, current consumption per person is unsustainable because it depletes capital per person.

Gender inequalities from the demographic perspective

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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

Transition operators in electromagnetic-wave diffraction theory - General theory

Science.gov (United States)

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.

[The beginnings of the demographic transition in Croatia and its socioeconomic foundations (until 1918)].

Science.gov (United States)

Karaman, I

1986-01-01

This is a historical survey of the process of modernization and the formulation of political and economic systems in Croatia, Yugoslavia, from the mid-nineteenth century to the present. Population dynamics and concurrent demographic transitions are addressed. (SUMMARY IN ENG AND RUS)

Random matrix theory for transition strengths: Applications and open questions

Science.gov (United States)

Kota, V. K. B.

2017-12-01

Embedded random matrix ensembles are generic models for describing statistical properties of finite isolated interacting quantum many-particle systems. 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 (then the initial and final systems are same), nuclear beta and double beta decay (then the initial and final systems are different) and so on. Using embedded ensembles (EE), there are efforts to derive a good statistical theory for transition strengths. With m fermions (or bosons) in N mean-field single particle levels and interacting via two-body forces, we have with GOE embedding, the so called EGOE(1+2). Now, the transition strength density (transition strength multiplied by the density of states at the initial and final energies) is a convolution of the density generated by the mean-field one-body part with a bivariate spreading function due to the two-body interaction. Using the embedding U(N) algebra, it is established, for a variety of transition operators, that the spreading function, for sufficiently strong interactions, is close to a bivariate Gaussian. Also, as the interaction strength increases, the spreading function exhibits a transition from bivariate Breit-Wigner to bivariate Gaussian form. In appropriate limits, this EE theory reduces to the polynomial theory of Draayer, French and Wong on one hand and to the theory due to Flambaum and Izrailev for one-body transition operators on the other. Using spin-cutoff factors for projecting angular momentum, the theory is applied to nuclear matrix elements for neutrinoless double beta decay (NDBD). In this paper we will describe: (i) various developments in the EE theory for transition strengths; (ii) results for nuclear matrix elements for 130Te and 136Xe NDBD; (iii) important open questions in the current form of the EE theory.

Deconfinement and the Hagedorn transition in string theory.

Science.gov (United States)

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)(*)transitioning through a precise inverse power law at a critical temperature T(D) = T(H)r(*)/(2alpha('))(1/2)pi.

Gauge theory of glass transition

International Nuclear Information System (INIS)

Vasin, Mikhail

2011-01-01

A new analytical approach for the description of the glass transition in a frustrated system is suggested. The theory is based on the non-equilibrium dynamics technique, and takes into account the interaction of the local order field with the massive gauge field, which describes frustration-induced plastic deformation. The glass transition is regarded as a phase transition interrupted because of the premature critical slowing-down of one of the degrees of freedom caused by the frustrations. It is shown that freezing of the system appears when the correlation length and relaxation time of the gauge field diverge. The Vogel–Fulcher–Tammann relation for the transition kinetics and the critical exponent for the nonlinear susceptibility, 2.5∼ t correlation function dependence on time, and explains the boson peak appearance on this curve. In addition, the function of the glass transition temperature value with cooling rate is derived; this dependence fully conforms with known experimental data

A Quantum Version of Wigner’s Transition State Theory

NARCIS (Netherlands)

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

Growth-based Theories for Declining Regions? A Note on Conceptualisations of Demographic Change for Regional Economic Development

Directory of Open Access Journals (Sweden)

Anke Matuschewski

2016-01-01

Full Text Available This article aims to critically assess the economic growth paradigm, which typically underlies most approaches to regional policymaking for demographic change. While population losses, ageing and outmigration – i.e. phenomena that are addressed as demographic change – have become a matter of urgency for many European regions, most regional economic development theories remain silent about the population decline affecting the economic growth and development prospects of regions. Consequently, regional policies usually rely on the concept of economic growth, yet neglect the complexity and importance of demographic change and how it relates to the economic sphere. Due to this lack in nuance, we argue that regional policymaking fails to design adequate policy support for regions facing persistent demographic change and economic stagnation or decline as a result. Based on these observations, the paper examines a selection of regional economic development theories in search for alternative concepts of growth and development in the context of demographic change. To this aim, globalisation peripheries are introduced as a fruitful conceptual point of reference and, in combination with endogenous regional development theories, discussed as an alternative approach for regional policymaking.

Vibrational nonadiabaticity and tunneling effects in transition state theory

International Nuclear Information System (INIS)

Marcus, R.A.

1979-01-01

The usual quantum mechanical derivation of transition state theory is a statistical one (a quasi-equilibrium is assumed) or dynamical. The typical dynamical one defines a set of internal states and assumes vibrational adiabaticity. Effects of nonadiabaticity before and after the transition state are included in the present derivation, assuming a classical treatment of the reaction coordinate. The relation to a dynamical derivation of classical mechanical transition state theory is described, and tunneling effects are considered

Theory of K-MM radiative-Auger transitions

International Nuclear Information System (INIS)

Baptista, G.B.

1975-01-01

Presently available calculations of transition probabilities for radiative-Auger and double-Auger processes are based on shake-off theory. In this theory, such processes are thought of as being due to electron core rearrangement associated with de-excitation of an inner shell vacancy. It is suggested that radiative-Auger processes result from the interaction of two electrons with one another and the radiation field in the presence of an inner shell vacancy, while double-Auger processes result from the interaction of an electron with two electrons in the presence of a similar vacancy. Expressions for the transition probabilities of these processes are derived in second order time dependent perturbation theory. The interaction is taken as the sum of the Coulomb interaction and electron-field interaction of the electrons involved. This approach allows calculation of the detailed photon or electron energy distribution resulting from such processes, as well as the relative and absolute transition rates involved. As a specific example of this approach the transition probability for the K-MM radiative-Auger effect in argon is calculated and compared with available experimental data. Scaled Thomas-Fermi wavefunctions are used to calculate the total transition probability which is found to be 2.68 x 10 -4 eV/h-bar In addition, the spectral distribution of emitted photons is obtained, and agreement both in magnitude and with the general features of the experimental data is excellent

Linking Complexity and Sustainability Theories: Implications for Modeling Sustainability Transitions

Directory of Open Access Journals (Sweden)

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.

Quantifying the limits of transition state theory in enzymatic catalysis.

Science.gov (United States)

Zinovjev, Kirill; Tuñón, Iñaki

2017-11-21

While being one of the most popular reaction rate theories, the applicability of transition state theory to the study of enzymatic reactions has been often challenged. The complex dynamic nature of the protein environment raised the question about the validity of the nonrecrossing hypothesis, a cornerstone in this theory. We present a computational strategy to quantify the error associated to transition state theory from the number of recrossings observed at the equicommittor, which is the best possible dividing surface. Application of a direct multidimensional transition state optimization to the hydride transfer step in human dihydrofolate reductase shows that both the participation of the protein degrees of freedom in the reaction coordinate and the error associated to the nonrecrossing hypothesis are small. Thus, the use of transition state theory, even with simplified reaction coordinates, provides a good theoretical framework for the study of enzymatic catalysis. Copyright © 2017 the Author(s). Published by PNAS.

Hyperconifold transitions, mirror symmetry, and string theory

Science.gov (United States)

Davies, Rhys

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 and Z 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 or Z. 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.

Hyperconifold transitions, mirror symmetry, and string theory

International Nuclear Information System (INIS)

Davies, Rhys

2011-01-01

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 3 and Z 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 3 or Z 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.

The Effects of the Demographic Transition on Economic Growth : Implications for Japan

OpenAIRE

Sundman, Marie-Lor

2011-01-01

Demographic transition implies severe challenges for high income nations, for instance Japan, as the population decreases due to declines in birth rates as well as the higher rate of elderly population. More women are entering the labor market which affects birth rates. In addition, technological progress has improved health care and standard of living, bringing up life expectancies. However, the elderly population is increasing, elevating the dependency ratio which dampens the economic growt...

Phase transition in SO(3) gauge theory

International Nuclear Information System (INIS)

Datta, Saumen; Gavai, Rajiv V.

1998-01-01

The phase transition in SO(3) lattice gauge theory is investigated by Monte Carlo techniques with a view (i) to understand the relationship between the bulk transition and the deconfinement transition, and (ii) to resolve the current ambiguity about the nature of the high temperature phase. By introduction of a magnetic field, it was shown that the +ve and -ve values of a > correspond to the same phase. Studies on different sized lattices lead to the conclusion that in SO(3), there is only one transition, which is deconfining in nature. (author)

Demographic transition and population ageing in India: Implications on the elderly of the future

Directory of Open Access Journals (Sweden)

Shradha Mathur

2015-01-01

Full Text Available Ageing population of India will transform into the elderly in future. The issue of health of the elderly population in India has arrested the attention of health policy makers and the researchers, in the recent past. Demographic structure, quality of life, healthcare services and government planning have serious implications on the ageing population. The objective of the research article is to systematically and critically evaluate the impact of demographic transition, projected demographic indicators and changing population characteristics on the health status of the elderly persons living in India in the coming decades. Analysis and discussions are based on secondary data published by the Ministry of Health and Family Welfare of the Government of India. The results indicate that India will be an ageing nation in the coming years and improvements in health, education and government planning are likely to enhance the life expectancy of the elderly, while the share of children will reduce, suggesting an increase in dependency of the older persons on the adult population. The article provides insights into workable solutions and suggests key recommendations to attain faster demographic dividend. India would be competing with the pressure of a dramatic demographic bulge in future.

Explore Stochastic Instabilities of Periodic Points by Transition Path Theory

Science.gov (United States)

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.

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.

Several problems of the theory of transition radiation and transition scattering

International Nuclear Information System (INIS)

Ginzburg, V.L.; Tsytovich, V.N.

1979-01-01

The process of transition radiation is a very general one. It appears if some source, which does not have a proper frequency (for example a point charge, multipole etc), is moving with a constant velocity in an inhomogeneous and/or nonstationary medium. In the case of a periodic medium the transition radiation has some special peculiarities and is called the resonance transition radiation or transition scattering. Transition scattering occurs particularly in the case when some wave of dielectric permittivity acts on a nonmoving (fixed) charge. The processes of transition radiation and transition scattering have analogies outside electrodynamics similarly to the Vavilov-Cherenkov emission. The latter occurs also for a source moving with a constant velocity but in a homogeneous medium (and only if the velocity of the source exceeds the wave phase velocity in the medium). The present review is dealing with several problems of the theory of transition radiation and transition scattering. Attention is paid mainly to the formulation of the problems and to revealing characterisic features and peculiarities of the phenomena described. (Auth.)

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...

Light-front quantized field theory: (an introduction). Spontaneous symmetry breaking. Phase transition in φ4 theory

International Nuclear Information System (INIS)

Srivastava, P.P.

1993-01-01

The field theory quantized on the light-front is compared with the conventional equal-time quantized theory. The arguments based on the micro causality principle would imply that the light-front field theory may become nonlocal with respect to the longitudinal coordinate even though the corresponding equal-time formulation is local. This is found to be the case for the scalar theory. The conventional instant form theory is sometimes required to be constrained by invoking external physical considerations; the analogous conditions seem to be already built in the theory on the light-front. In spite of the different mechanisms of the spontaneous symmetry breaking in the two forms of dynamics they result in the same physical content. The phase transition in (φ 4 ) 2 theory is also discussed. The symmetric vacuum state for vanishingly small couplings is found to turn into an unstable symmetric one when the coupling is increased and may result in a phase transition of the second order in contrast to the first order transition concluded from the usual variational methods. (author)

Modern aspects of the kinetic theory of glass transition

International Nuclear Information System (INIS)

Tropin, T V; Aksenov, V L; Schmelzer, J W

2016-01-01

This paper reviews glass transition kinetics models that are developed to describe the formation of structural (for example, covalent and metallic) glasses, as well as to account for the transition of a polymer to a solid glassy state. As the two approaches most frequently used over the last decade to model the glass transition, the Tool–Narayanaswamy–Moynihan model and the Adam–Gibbs theory of glass transition are described together with examples of their applications. Also discussed are entropy-based approaches that rely on irreversible thermodynamics methods originated in the work of De Donder, Mandelstam, and Leontovich. The actual problems that arise in applying these methods and the prospects of their development are discussed. A brief overview of statistical glass transition models is given, including the mode-coupling and energy-landscape theories. (reviews of topical problems)

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.

Men's passage to fatherhood: an analysis of the contemporary relevance of transition theory

OpenAIRE

Draper, Janet

2003-01-01

This paper presents a theoretical analysis of men's experiences of pregnancy, birth and early fatherhood. It does so using a framework of ritual transition theory and argues that despite its earlier structural-functionalist roots, transition theory remains a valuable framework, illuminating contemporary transitions across the life course. The paper discusses the historical development of transition or ritual theory and, drawing upon data generated during longitudinal ethnographic interviews w...

Theory of free-bound transitions in channeling radiation

International Nuclear Information System (INIS)

Saenz, A.W.; Nagl, A.; Uberall, H.

1988-01-01

On the basis of a single-string model, we derive formulas for the transition strengths of free-bound transitions of axially channeled electrons. We illustrate the theory by numerical calculations of these strengths for 3.5-MeV electrons in Si. Experimental evidence for such transitions has been obtained previously [J.U. Andersen et al., Nucl. Instrum. Methods 194, 209 (1982)] and is in good qualitative agreement with our calculations

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 ...

Is there a Demographic Time-bomb?

DEFF Research Database (Denmark)

Greve, Bent

2006-01-01

The article discuss whether the demographic transition in Europe will have any impact on the future of the European welfare states......The article discuss whether the demographic transition in Europe will have any impact on the future of the European welfare states...

SINGAPORE'S DEMOGRAPHIC TRANSITION, THE LABOR FORCE AND GOVERNMENT POLICIES: THE LAST FIFTY YEARS

OpenAIRE

MUI TENG YAP; CHRISTOPHER GEE

2015-01-01

The trajectory of Singapore's population size and composition can be mapped out with its progression through the various phases of demographic transition from high birth and death rates in the post-war years to very low birth and death rates today, all within the context of rapid economic and social development that has taken place in the past 50 years. Population planning has been integral in Singapore's national development strategy, balancing the economy's needs for more and better qualifi...

Integrating transition theory and bioecological theory: a theoretical perspective for nurses supporting the transition to adulthood for young people with medical complexity.

Science.gov (United States)

Joly, Elizabeth

2016-06-01

To present a discussion of a theoretical perspective developed through integrating Meleis' Transition Theory and Bronfenbrenner's Bioecological Theory of Human Development to inform nursing and advanced nursing practice supporting the transition to adulthood for young people with medical complexity. Theoretical perspectives to inform nursing practice in supporting successful transition are limited, yet nurses frequently encounter young people with medical complexity during the transition to adulthood. Discussion paper. A literature search of CINAHL and Medline was conducted in 2014 and included articles from 2003-2014; informal discussions with families; the author's experiences in a transition program. The integrated theoretical perspective described in this paper can inform nurses and advanced practice nurses on contextual influences, program and intervention development across spheres of influence and outcomes for the transition to adulthood for young people with medical complexity. Young people and their families require effective reciprocal interactions with individuals and services across sectors to successfully transition to adulthood and become situated in the adult world. Intervention must also extend beyond the young person to include providers, services and health and social policy. Nurses can take a leadership role in supporting the transition to adulthood for young people with medical complexity through direct care, case management, education and research. It is integral that nurses holistically consider developmental processes, complexity and contextual conditions that promote positive outcomes during and beyond the transition to adulthood. © 2016 John Wiley & Sons Ltd.

Transition state theory for enzyme kinetics

Science.gov (United States)

Truhlar, Donald G.

2015-01-01

This article is an essay that discusses the concepts underlying the application of modern transition state theory to reactions in enzymes. Issues covered include the potential of mean force, the quantization of vibrations, the free energy of activation, and transmission coefficients to account for nonequilibrium effect, recrossing, and tunneling. PMID:26008760

Modal Transition Systems as the Basis for Interface Theories and Product Lines

DEFF Research Database (Denmark)

Nyman, Ulrik

and a subset of modal transition systems is proved. The developed interface theory, which can describe liveness properties, is also applied as a behavioral variability theory for product line development. The two last papers of the thesis concern themselves with modal and mixed transition systems. The first....... It also proves PSPACE-hardness for consistency of mixed specifications and establishes a number of reductions between the different decision problems. Keywords: Modeling, Software Product Lines, Embedded Software, Modal Refinement, Labeled Transition Systems, Modal Transition Systems, Mixed Transition......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...

Dimensions of Rational Decision-Making during the Demographic Transition; Aranjuez (Spain Revisited

Directory of Open Access Journals (Sweden)

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.

Effective field theory and integrability in two-dimensional Mott transition

International Nuclear Information System (INIS)

Bottesi, Federico L.; Zemba, Guillermo R.

2011-01-01

Highlights: → Mott transition in 2d lattice fermion model. → 3D integrability out of 2D. → Effective field theory for Mott transition in 2d. → Double Chern-Simons. → d-Density waves. - Abstract: We study the Mott transition in a two-dimensional lattice spinless fermion model with nearest neighbors density-density interactions. By means of a two-dimensional Jordan-Wigner transformation, the model is mapped onto the lattice XXZ spin model, which is shown to possess a quantum group symmetry as a consequence of a recently found solution of the Zamolodchikov tetrahedron equation. A projection (from three to two space-time dimensions) property of the solution is used to identify the symmetry of the model at the Mott critical point as U q (sl(2)-circumflex)xU q (sl(2)-circumflex), with deformation parameter q = -1. Based on this result, the low-energy effective field theory for the model is obtained and shown to be a lattice double Chern-Simons theory with coupling constant k = 1 (with the standard normalization). By further employing the effective filed theory methods, we show that the Mott transition that arises is of topological nature, with vortices in an antiferromagnetic array and matter currents characterized by a d-density wave order parameter. We also analyze the behavior of the system upon weak coupling, and conclude that it undergoes a quantum gas-liquid transition which belongs to the Ising universality class.

Assessment of a transitional boundary layer theory at low hypersonic Mach numbers

Science.gov (United States)

Shamroth, S. J.; Mcdonald, H.

1972-01-01

An investigation was carried out to assess the accuracy of a transitional boundary layer theory in the low hypersonic Mach number regime. The theory is based upon the simultaneous numerical solution of the boundary layer partial differential equations for the mean motion and an integral form of the turbulence kinetic energy equation which controls the magnitude and development of the Reynolds stress. Comparisions with experimental data show the theory is capable of accurately predicting heat transfer and velocity profiles through the transitional regime and correctly predicts the effects of Mach number and wall cooling on transition Reynolds number. The procedure shows promise of predicting the initiation of transition for given free stream disturbance levels. The effects on transition predictions of the pressure dilitation term and of direct absorption of acoustic energy by the boundary layer were evaluated.

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.

Factors Associated with Short-Term Transitions of Nondaily Smokers: Socio-demographic Characteristics and Other Tobacco Product Use

Science.gov (United States)

Wang, Yingning; Sung, Hai-Yen; Yao, Tingting; Lightwood, James; Max, Wendy

2016-01-01

Aims To examine the transitions in smoking status among nondaily smokers who transitioned to daily or former smokers or remained as nondaily smokers over a 12-month period. We analyzed factors associated with these transitions, including the use of cigars and smokeless tobacco (SLT). Design Secondary data analyses using pooled data from the 2003, 2006/07 and 2010/11 Tobacco Use Supplements to the Current Population Survey (TUS-CPS). Setting USA Participants Self-respondents aged 18+ who have smoked for more than 5 years and were nondaily smokers 12 months before the interview (n = 13,673 or 14.5% of current smokers). Measurements Multinomial logistic regression model to determine the correlates of nondaily-to-daily, stable nondaily, and nondaily-to-former smoking transitions among nondaily smokers at baseline. The model controlled for socio-demographic factors and the use of cigars and SLT. Findings 2.6% of adults in our sample were nondaily smokers at baseline. Among these, 69.7% remained nondaily smokers (stable nondaily smokers), 18.4% became daily smokers (nondaily-to-daily smokers), and 11.9% quit smoking (nondaily-to-former smokers) after 12 months. The nondaily-to-daily vs. stable nondaily smoking transition was less likely among those who were aged 65+ (p=0.018), male (pnon-Hispanic Asian (p=0.032), without a college degree, widowed/divorced/separated (p=0.013) or never married (p=0.011), and current users of cigars (p=0.003) compared with the appropriate reference group. Conclusions While over two-thirds of nondaily smokers in the USA remain as such after 12 months, others become daily smokers or quit. The likelihood of remaining stable nondaily smokers and of transition from nondaily-to-daily and nondaily-to-former smokers is associated with socio-demographics factors and current use of cigars and smokeless tobacco. PMID:27886652

Correlated effective field theory in transition metal compounds

International Nuclear Information System (INIS)

Mukhopadhyay, Subhasis; Chatterjee, Ibha

2004-01-01

Mean field theory is good enough to study the physical properties at higher temperatures and in higher dimensions. It explains the critical phenomena in a restricted sense. Near the critical temperatures, when fluctuations become important, it may not give the correct results. Similarly in low dimensions, the correlations become important and the mean field theory seems to be inadequate to explain the physical phenomena. At low-temperatures too, the quantum correlations become important and these effects are to be treated in an appropriate way. In 1974, Prof. M.E. Lines of Bell Laboratories, developed a theory which goes beyond the mean field theory and is known as the correlated effective field (CEF) theory. It takes into account the fluctuations in a semiempirical way. Lines and his collaborators used this theory to explain the short-range correlations and their anisotropy in the paramagnetic phase. Later Suzuki et al., Chatterjee and Desai, Mukhopadhyay and Chatterjee applied this theory to the magnetically ordered phase and a tremendous success of the theory has been found in real systems. The success of the CEF theory is discussed in this review. In order to highlight the success of this theory, earlier effective field theories and their improvements over mean field theories e.g., Bethe-Peierls-Weiss method, reaction field approximation, etc., are also discussed in this review for completeness. The beauty of the CEF theory is that it is mean field-like, but captures the essential physics of real systems to a great extent. However, this is a weak correlated theory and as a result is inappropriate for the metallic phase when strong correlations become important. In recent times, transition metal oxides become important due to the discovery of the high-temperature superconductivity and the colossal magnetoresistance phenomena. These oxides seem to be Mott insulators and undergo an insulator to metal transition by applying magnetic field, pressure and by changing

DEMOGRAPHIC POLICY AND THE ANALYSIS OF IRRETRIEVABLE LOSSES OF PUBLIC HEALTH BASED ON THE CONCEPT OF THE EPIDEMIOLOGICAL TRANSITION

Directory of Open Access Journals (Sweden)

Юрий Аркадьевич Григорьев

2017-09-01

Full Text Available From the general positions of population dynamics, the demographic policy is considered, its regional features in the East of Russia are designated. It is necessary to consolidate the positive traditions of the moral and legal norms of the society and the harmonious personality development. It takes their long-term translation for the improvement of the person himself, his family-marriage relations to support the forms of demographic behavior aimed at the expanded population reproduction. The solution of the numerous tasks of the demographic policy presupposes further scientific (theoretical and applied studies of the features of the socio-demographic and medico-demographic development of the Russian regions. Particular attention should be paid to the analysis of the main characteristics of the epidemiological transition, where mortality, as well as birth rate, is one of the main characteristics of the population reproduction. This will make it possible to define more precisely the prediction of the value of irretrievable losses with endogenous and exogenous determination, to estimate on this basis the reserves of increasing life expectancy through the measures of demographic policy.

Heavy quark effective theory and heavy baryon transitions

International Nuclear Information System (INIS)

Hussain, F.

1992-01-01

The heavy quark effective theory (HQET) is applied to study the weak decay of heavy mesons and heavy baryons and to predict the form factors for heavy to heavy and heavy to light transitions. 28 refs, 10 figs, 2 tabs

Quasi-liquid layer theory based on the bulk first-order phase transition

International Nuclear Information System (INIS)

Ryzhkin, I. A.; Petrenko, V. F.

2009-01-01

The theory of the superionic phase transition (bulk first-order transition) proposed in [1] is used to explain the existence of a quasi-liquid layer at an ice surface below its melting point. An analytical expression is derived for the quasi-liquid layer thickness. Numerical estimates are made and compared with experiment. Distinction is made between the present model and other quasi-liquid layer theories

Some aspects of transition radiation and scattering theory

International Nuclear Information System (INIS)

Ginzburg, V.L.; Tsytovich, V.N.

1978-01-01

Some aspects of transition radiation and transition scattering theory are considered. The transition radiation in vacuum is analysed in the presence of a strong magnetic field. It is shown, that the constant electro-magnetic field makes vacuum similar to the uniaxial ferrodielectric. The appearance of the transition radiation in the nonstationary medium is discussed when its properties in the medium change abruptly in time. It is obtained, that both types of the transition radiation for nonrelativistic particles (on an abrupt boundary of the two media interface and under an abrupt change in time of the medium properties) differ quantitatively (on the order of the value). The role of the radiation transition and scattering in plasma physics has been elucidated from different points. Four most important features of these processes are pointed out. Particularly, essential is shown to be the type of the transition scattering when one plasma wave, being the dielectric constant wave transforms into another one also a plasma wave. In the processes of the transition scattering an essential part is played by the effects of the space dispersion, particularly when the scattering takes place on the small velocity particles. Finally besides transition scattering there exists in plasma or in some cases prevails a Thomson scattering. In this case an important role in plasma is played by the interference between the Thomson and the transition scattering

Light-front quantized field theory (an introduction): spontaneous symmetry breaking. Phase transition in φ4 theory

International Nuclear Information System (INIS)

Srivastava, Prem P.

1994-01-01

The Dirac procedure is used to construct the Hamiltonian formulation of the scalar field theory on the light-front. The theory is quantized and the mechanism of the spontaneous symmetry breaking in the front form and the instant form dynamics are compared. The phase transition in (φ 4 )2 theory is also discussed and found to be of the second order. (author). 36 refs

Second-order phase transition in gφ42 theory

International Nuclear Information System (INIS)

Ganbold, G.; Efimov, G.V.

1993-08-01

We have suggested a regular scheme for calculating systematically the leading term and next corrections to it up to the fourth order for the effective potential in the scalar φ 4 2 theory. The obtained results give evidence in favour of a second-order phase transition at (g/2πm 2 ) crit ≅ 0.9 in the theory under consideration. (author). 18 refs, 1 fig

Systematic expansion in the order parameter for replica theory of the dynamical glass transition.

Science.gov (United States)

Jacquin, Hugo; Zamponi, Francesco

2013-03-28

It has been shown recently that predictions from mode-coupling theory for the glass transition of hard-spheres become increasingly bad when dimensionality increases, whereas replica theory predicts a correct scaling. Nevertheless if one focuses on the regime around the dynamical transition in three dimensions, mode-coupling results are far more convincing than replica theory predictions. It seems thus necessary to reconcile the two theoretic approaches in order to obtain a theory that interpolates between low-dimensional, mode-coupling results, and "mean-field" results from replica theory. Even though quantitative results for the dynamical transition issued from replica theory are not accurate in low dimensions, two different approximation schemes--small cage expansion and replicated hyper-netted-chain (RHNC)--provide the correct qualitative picture for the transition, namely, a discontinuous jump of a static order parameter from zero to a finite value. The purpose of this work is to develop a systematic expansion around the RHNC result in powers of the static order parameter, and to calculate the first correction in this expansion. Interestingly, this correction involves the static three-body correlations of the liquid. More importantly, we separately demonstrate that higher order terms in the expansion are quantitatively relevant at the transition, and that the usual mode-coupling kernel, involving two-body direct correlation functions of the liquid, cannot be recovered from static computations.

Value Orientations and the Second Demographic Transition (SDT in Northern, Western and Southern Europe: An Update

Directory of Open Access Journals (Sweden)

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

[On the economy of "wealth of people": demographic-political theories in the Austria of enlightened absolutism].

Science.gov (United States)

Wichtl, T

1985-01-01

"This essay focuses on mercantilist theories and interpretations of demographic trends [in Austria] in the late 18th century." The writings of several mercantilist authors are summarized, and the influence of their views on population policy is discussed. It is noted that the official population policy, which aimed at fast population growth to strengthen the economy and increase the number of soldiers, was based on the mercantilist theory that greater population size means higher per capita incomes. (summary in ENG) excerpt

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.

Knox meets Cox: adapting epidemiological space-time statistics to demographic studies.

Science.gov (United States)

Schmertmann, Carl P; Assuçãon, Renato M; Potter, Joseph E

2010-08-01

Many important questions and theories in demography focus on changes over time, and on how those changes differ over geographic and social space. Space-time analysis has always been important in studying fertility transitions, for example. However demographers have seldom used formal statistical methods to describe and analyze time series of maps. One formal method, used widely in epidemiology, criminology, and public health, is Knox 's space-time interaction test. In this article, we discuss the potential of the Knox test in demographic research and note some possible pitfalls. We demonstrate how to use familiar proportional hazards models to adapt the Knox test for demographic applications. These adaptations allow for nonrepeatable events and for the incorporation of structural variables that change in space and time. We apply the modified test to data on the onset offertility decline in Brazil over 1960-2000 and show how the modified method can produce maps indicating where and when diffusion effects seem strongest, net of covariate effects.

Saudi Deaf Students Post-Secondary Transitioning Experience: A Grounded Theory Study

Science.gov (United States)

Almotiri, Abdullah

2017-01-01

Understanding how deaf and hard-of-hearing (DHH) international students transition to post-secondary institutions is important for ensuring their academic and personal success. In this grounded theory study, five Saudi Arabian students who are DHH and enrolled at Gallaudet University were interviewed about their transition experience. Participants…

Self-consistent theory of normal-to-superconducting transition

International Nuclear Information System (INIS)

Radzihovsky, L.; Chicago Univ., IL

1995-01-01

I study the normal-to-superconducting (NS) transition within the Ginzburg-Landau (GL) model, taking into account the fluctuations in the m-component complex order parameter ψ α and the vector potential A in the arbitrary dimension d, for any m. I find that the transition is of second order and that the previous conclusion of the fluctuation-driven first-order transition is a possible artifact of the breakdown of the ε-expansion and the inaccuracy of the 1/m-expansion for physical values ε = 1, m 1. I compute the anomalous η(d, m) exponent at the NS transition, and find η(3, 1) ∼ -0.38. In the m → ∞ limit, η(d, m) becomes exact and agrees with the 1/m-expansion. Near d = 4 the theory is also in good agreement with the perturbative ε-expansion results for m > 183 and provides a sensible interpolation formula for arbitrary d and m. (orig.)

Role of secondary instability theory and parabolized stability equations in transition modeling

Science.gov (United States)

El-Hady, Nabil M.; Dinavahi, Surya P.; Chang, Chau-Lyan; Zang, Thomas A.

1993-01-01

In modeling the laminar-turbulent transition region, the designer depends largely on benchmark data from experiments and/or direct numerical simulations that are usually extremely expensive. An understanding of the evolution of the Reynolds stresses, turbulent kinetic energy, and quantifies in the transport equations like the dissipation and production is essential in the modeling process. The secondary instability theory and the parabolized stability equations method are used to calculate these quantities, which are then compared with corresponding quantities calculated from available direct numerical simulation data for the incompressible boundary-layer flow of laminar-turbulent transition conditions. The potential of the secondary instability theory and the parabolized stability equations approach in predicting these quantities is discussed; results indicate that inexpensive data that are useful for transition modeling in the early stages of the transition region can be provided by these tools.

Mapping entropy: Analysis of population-environment dynamics using integrated remote sensing and transition theory based on a general systems perspective

Science.gov (United States)

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

Nonperturbative approach to quantum field theories: phase transitions and confinement

International Nuclear Information System (INIS)

Yankielowicz, S.

1976-08-01

Lectures are given on a nonperturbative approach to quantum field theories. Phenomena are discussed for which the usual weak coupling perturbative approach in terms of Feynman diagrams is of no assistance. Properties associated with large distance behavior, i.e., phase transitions, low lying spectra, coherent excitations which are presumably built out of the long wave structure of the theory are described. These methods are important for the study of strong coupling field theories and the question of quarks confinement. 25 references

How do demographic transitions and public health policies affect patients with Parkinson’s disease in Brazil?

Directory of Open Access Journals (Sweden)

Bovolenta TM

2017-01-01

Full Text Available Tânia M Bovolenta, Andre C Felicio R. Neurology Program, Hospital Israelita Albert Einstein, São Paulo, Brazil Abstract: 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. Keywords: Parkinson’s disease, demographic transition, public health, health assistance financing

Z3 - invariant effective theory of deconfining phase transition

International Nuclear Information System (INIS)

So, Hiroto

1986-01-01

A Z 3 -invariant scalar model is proposed as an effective theory of deconfining phase transition of QCD. Coupling constants in the potential are determined by Monte Carlo methods. The structure of renormalization trajectories for coupling constants is investigated. (author)

Quantum field theory and phase transitions: universality and renormalization group; Theorie quantique des champs et transitions de phase: universalite et groupe de renormalisation

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.)

Phase transitions and topological excitations in hypergauge theories

International Nuclear Information System (INIS)

Nencka-Ficek, H.

1985-01-01

The problems connected with the phase structure of antisymmetric tensor gauge fields are investigated. (s+1)-dimensional hyperloops cannot be constructed in (s+1)-dimensional lattices. This is the cause of a lack of phase transitions in the U(1) theories with fields being sth-kind gauge invariant in the (s+1)-dimensional lattice

Transition theory and its relevance to patients with chronic wounds.

Science.gov (United States)

Neil, J A; Barrell, L M

1998-01-01

A wound, in the broadest sense, is a disruption of normal anatomic structure and function. Acute wounds progress through a timely and orderly sequence of repair that leads to the restoration of functional integrity. In chronic wounds, this timely and orderly sequence goes awry. As a result, people with chronic wounds often face not only physiological difficulties but emotional ones as well. The study of body image and its damage as a result of a chronic wound fits well with Selder's transition theory. This article describes interviews with seven patients with chronic wounds. The themes that emerged from those interviews were compared with Selder's theory to describe patients' experience with chronic wounds as a transition process that can be identified and better understood by healthcare providers.

Deconfinement phase transition and finite-size scaling in SU(2) lattice gauge theory

International Nuclear Information System (INIS)

Mogilevskij, O.A.

1988-01-01

Calculation technique for deconfinement phase transition parameters based on application of finite-size scaling theory is suggested. The essence of the technique lies in plotting of universal scaling function on the basis of numerical data obtained at different-size final lattices and discrimination of phase transition parameters for infinite lattice system. Finite-size scaling technique was developed as applied to spin system theory. β critical index for Polyakov loop and SU(2) deconfinement temperature of lattice gauge theory are calculated on the basis of finite-size scaling technique. The obtained value agrees with critical index of magnetization in Ising three-dimensional model

The high temperature phase transition for the φ4 theory

International Nuclear Information System (INIS)

Tetradis, N.

1994-01-01

The use of the perturbative temperature dependent effective potential for the study of second order or weakly first order phase transitions is problematic, due to the appearance of infrared divergences. These divergences can be controlled through the method of the effective average action which employs renormalization group ideas. I review work done with C. Wetterich on the study of the high temperature phase transition for the N-component Φ 4 theory. A detailed quantitative picture of the second order phase transition is presented, including the critical exponents for the behaviour in the vicinity of the critical temperature. (orig.)

Transitional clerkship: an experiential course based on workplace learning theory.

Science.gov (United States)

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.

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.

The 'silent' phase transition in mesonic bags and lattice theory

International Nuclear Information System (INIS)

Dey, J.; Dey, M.; Araujo Junior, C.F. de; Tomio, L.

1993-10-01

It is shown that even the simple bag model is able to reproduce the lattice result for the masses and the sound velocity, at finite temperature, T, suggests that the transition point depends on the nature of the meson. It would be interesting to check the last conclusion in present day finite temperature lattice theory, since different transition points seem to be indicated by particle emission T in heavy ion reactions. (author)

Reservoir theory, groundwater transit time distributions, and lumped parameter models

International Nuclear Information System (INIS)

Etcheverry, D.; Perrochet, P.

1999-01-01

The relation between groundwater residence times and transit times is given by the reservoir theory. It allows to calculate theoretical transit time distributions in a deterministic way, analytically, or on numerical models. Two analytical solutions validates the piston flow and the exponential model for simple conceptual flow systems. A numerical solution of a hypothetical regional groundwater flow shows that lumped parameter models could be applied in some cases to large-scale, heterogeneous aquifers. (author)

Ignition And Transition Conditions In The Theory Of Combustion ...

African Journals Online (AJOL)

In branched-chain thermal explosion theory, it is usually impossible analytically and sometimes a substantial computation to calculate the temperature, activation energy and modiûed Semenov's number at transition from discontinuous to continuous behaviour. Invariably, it is possible to reduce the governing equation to ...

Demographic Evolution in Romania – Convergence or Peripherisation?

Directory of Open Access Journals (Sweden)

Adriana Veronica Litra

2006-02-01

Full Text Available Romania began its demographic transition about one century later than the developed countries. We put the blame of this gap on the delayed economic, social and political development in comparison with the Western Europe. But also, it could not be forgotten the shift from a population forced and subdue by the totalitary regime, to a free people to decide when to have a child or how large should be the family. During transition, Romania has pointed many negative demographic evolutions, as compared with the other european countries. It may be said that the transition in Romania over the period 1990-2004 adjusted the classical pattern of demographic evolution. Not fully felt at this moment, we will probably find ourselves few decades later older, less, deprived of skilled labor force and unbalanced as gender ratio.

Surface hopping, transition state theory and decoherence. I. Scattering theory and time-reversibility.

Science.gov (United States)

Jain, Amber; Herman, Michael F; Ouyang, Wenjun; Subotnik, Joseph E

2015-10-07

We provide an in-depth investigation of transmission coefficients as computed using the augmented-fewest switches surface hopping algorithm in the low energy regime. Empirically, microscopic reversibility is shown to hold approximately. Furthermore, we show that, in some circumstances, including decoherence on top of surface hopping calculations can help recover (as opposed to destroy) oscillations in the transmission coefficient as a function of energy; these oscillations can be studied analytically with semiclassical scattering theory. Finally, in the spirit of transition state theory, we also show that transmission coefficients can be calculated rather accurately starting from the curve crossing point and running trajectories forwards and backwards.

A multistep general theory of transition to addiction.

Science.gov (United States)

Piazza, Pier Vincenzo; Deroche-Gamonet, Véronique

2013-10-01

Several theories propose alternative explanations for drug addiction. We propose a general theory of transition to addiction that synthesizes knowledge generated in the field of addiction into a unitary explanatory frame. Transition to addiction results from a sequential three-step interaction between: (1) individual vulnerability; (2) degree/amount of drug exposure. The first step, sporadic recreational drug use is a learning process mediated by overactivation of neurobiological substrates of natural rewards that allows most individuals to perceive drugs as highly rewarding stimuli. The second, intensified, sustained, escalated drug use occurs in some vulnerable individuals who have a hyperactive dopaminergic system and impaired prefrontal cortex function. Sustained and prolonged drug use induces incentive sensitization and an allostatic state that makes drugs strongly wanted and needed. Habit formation can also contribute to stabilizing sustained drug use. The last step, loss of control of drug intake and full addiction, is due to a second vulnerable phenotype. This loss-of-control-prone phenotype is triggered by long-term drug exposure and characterized by long-lasting loss of synaptic plasticity in reward areas in the brain that induce a form of behavioral crystallization resulting in loss of control of drug intake. Because of behavioral crystallization, drugs are now not only wanted and needed but also pathologically mourned when absent. This general theory demonstrates that drug addiction is a true psychiatric disease caused by a three-step interaction between vulnerable individuals and amount/duration of drug exposure.

Renormalization group theory of phase transitions in square Ising systems

International Nuclear Information System (INIS)

Nienhuis, B.

1978-01-01

Some renormalization group calculations are presented on a number of phase transitions in a square Ising model, both second and first order. Of these transitions critical exponents are calculated, the amplitudes of the power law divergences and the locus of the transition. In some cases attention is paid to the thermodynamic functions also far from the critical point. Universality and scaling are discussed and the renormalization group theory is reviewed. It is shown how a renormalization transformation, which relates two similar systems with different macroscopic dimensions, can be constructed, and how some critical properties of the system follow from this transformation. Several numerical and analytical applications are presented. (Auth.)

Non-Douglas-Kazakov phase transition of two-dimensional generalized Yang-Mills theories

International Nuclear Information System (INIS)

Khorrami, M.; Alimohammadi, M.

2007-01-01

In two-dimensional Yang-Mills and generalized Yang-Mills theories for large gauge groups, there is a dominant representation determining the thermodynamic limit of the system. This representation is characterized by a density, the value of which should everywhere be between zero and one. This density itself is determined by means of a saddle-point analysis. For some values of the parameter space, this density exceeds one in some places. So one should modify it to obtain an acceptable density. This leads to the well-known Douglas-Kazakov phase transition. In generalized Yang-Mills theories, there are also regions in the parameter space where somewhere this density becomes negative. Here too, one should modify the density so that it remains nonnegative. This leads to another phase transition, different from the Douglas-Kazakov one. Here the general structure of this phase transition is studied, and it is shown that the order of this transition is typically three. Using carefully-chosen parameters, however, it is possible to construct models with the order of the phase transition not equal to three. A class of these non-typical models is also studied. (orig.)

A Theory of Exoplanet Transits with Light Scattering

Energy Technology Data Exchange (ETDEWEB)

Robinson, Tyler D., E-mail: tydrobin@ucsc.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2017-02-20

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.

Quantum field theory and phase transitions: universality and renormalization group

International Nuclear Information System (INIS)

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.)

Theory of coherent transition radiation generated by ellipsoidal electron bunches

NARCIS (Netherlands)

Root, op 't W.P.E.M.; Smorenburg, P.W.; Oudheusden, van T.; Wiel, van der M.J.; Luiten, O.J.

2007-01-01

We present the theory of coherent transition radiation (CTR) generated by ellipsoidal electron bunches. We calculate analytical expressions for the electric field spectrum, the power spectrum, and the temporal electric field of CTR, generated by cylindrically symmetric ellipsoidal electron bunches

Theory of structural phase transition in MgTi{sub 2}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Talanov, V. M., E-mail: valtalanov@mail.ru [South Russian State Polytechnical University (Russian Federation); Shirokov, V. B. [Russian Academy of Sciences, South Science Centre (Russian Federation); Ivanov, V. V. [South Russian State Polytechnical University (Russian Federation); Talanov, M. V. [South Federal University (Russian Federation)

2015-01-15

A theory of phase transition in MgTi{sub 2}O{sub 4} is proposed based on a study of the order-parameter symmetry, thermodynamics, and mechanisms of formation of the atomic and orbital structure of the low-symmetry MgTi{sub 2}O{sub 4} phase. The critical order parameter (which induces a phase transition) is determined. It is shown that the calculated MgTi{sub 2}O{sub 4} tetragonal structure is a result of displacements of magnesium, titanium, and oxygen atoms; ordering of oxygen atoms; and the participation of d{sub xy}, d{sub xz}, and d{sub yz} orbitals. The contribution of noncritical representations to ion displacements is proven to be insignificant. The existence of various metal clusters in the tetragonal phase has been established by calculation in correspondence with experimental data. It is shown (within the Landau theory of phase transitions) that phase states can be changed as a result of both first- and second-order phase transitions: the high-symmetry phase borders two low-symmetry phases by second-order transition lines, while the border between low-symmetry phases is a first-order transition line.

Relaxation theory of spin-3/2 Ising system near phase transition temperatures

International Nuclear Information System (INIS)

Canko, Osman; Keskin, Mustafa

2010-01-01

Dynamics of a spin-3/2 Ising system Hamiltonian with bilinear and biquadratic nearest-neighbour exchange interactions is studied by a simple method in which the statistical equilibrium theory is combined with the Onsager's theory of irreversible thermodynamics. First, the equilibrium behaviour of the model in the molecular-field approximation is given briefly in order to obtain the phase transition temperatures, i.e. the first- and second-order and the tricritical points. Then, the Onsager theory is applied to the model and the kinetic or rate equations are obtained. By solving these equations three relaxation times are calculated and their behaviours are examined for temperatures near the phase transition points. Moreover, the z dynamic critical exponent is calculated and compared with the z values obtained for different systems experimentally and theoretically, and they are found to be in good agrement. (general)

Estimation and asymptotic theory for transition probabilities in Markov Renewal Multi–state models

NARCIS (Netherlands)

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

Phase transitions at finite chemical potential in grand unified theories

International Nuclear Information System (INIS)

Bailin, D.; Love, A.

1984-01-01

We discuss the circumstances in which non-zero chemical potentials might prevent symmetry restoration in phase transitions in the early universe at grand unification or partial unification scales. The general arguments are illustrated by consideration of SO(10) and SU(5) grand unified theories. (orig.)

Unlocking Hospitality Managers Career Transitions through Applying Schein's Career Anchors Theory

Science.gov (United States)

McGuire, David; Polla, Giovana; Heidl, Britta

2017-01-01

Purpose: This paper seeks to unlock the career transitions of hospitality managers through applying Schein's career anchors theory. It seeks to understand how Schein's Career Anchors help explain the career transitions of managers in the Scottish hospitality industry. Design/methodology/approach: The paper adopts a non-sequential multi-method…

Fracture and healing of elastomers: A phase-transition theory and numerical implementation

Science.gov (United States)

Kumar, Aditya; Francfort, Gilles A.; Lopez-Pamies, Oscar

2018-03-01

A macroscopic theory is proposed to describe, explain, and predict the nucleation and propagation of fracture and healing in elastomers undergoing arbitrarily large quasistatic deformations. The theory, which can be viewed as a natural generalization of the phase-field approximation of the variational theory of brittle fracture of Francfort and Marigo (1998) to account for physical attributes innate to elastomers that have been recently unveiled by experiments at high spatio-temporal resolution, rests on two central ideas. The first one is to view elastomers as solids capable to undergo finite elastic deformations and capable also to phase transition to another solid of vanishingly small stiffness: the forward phase transition serves to model the nucleation and propagation of fracture while the reverse phase transition models the possible healing. The second central idea is to take the phase transition to be driven by the competition between a combination of strain energy and hydrostatic stress concentration in the bulk and surface energy on the created/healed new surfaces in the elastomer. From an applications point of view, the proposed theory amounts to solving a system of two coupled and nonlinear PDEs for the deformation field and an order parameter, or phase field. A numerical scheme is presented to generate solutions for these PDEs in N = 2 and 3 space dimensions. This is based on an efficient non-conforming finite-element discretization, which remains stable for large deformations and elastomers of any compressibility, together with an implicit gradient flow solver, which is able to deal with the large changes in the deformation field that can ensue locally in space and time from the nucleation of fracture. The last part of this paper is devoted to presenting sample simulations of the so-called Gent-Park experiment. Those are confronted with recent experimental results for various types of silicone elastomers.

Reactive scattering theory for molecular transitions in time-dependent fields

International Nuclear Information System (INIS)

Peskin, U.; Miller, W.H.

1995-01-01

A new approach is introduced for computing probabilities of molecular transitions in time-dependent fields. The method is based on the stationary (t,t') representation of the Schroedinger equation and is shown to be equivalent to infinite order time-dependent perturbation theory. Bound-to-bound (i.e., photoexcitation) and bound-to-continuum (i.e., photoreaction) transitions are regarded as reactive collisions with the ''time coordinate'' as the reaction coordinate in an extended Hilbert space. A numerical method based on imposing absorbing boundary conditions for the time coordinate in a discrete variable representation framework is introduced. A single operation of the Green's operator provides all the state-specific transition probabilities as well as partial state-resolved (inclusive) reaction probabilities. Illustrative numerical applications are given for model systems

The Role of Spirituality in Transition to Parenthood: Qualitative Research Using Transformative Learning Theory.

Science.gov (United States)

Klobučar, Nataša Rijavec

2016-08-01

This article presents results of a qualitative study of 12 adult couples making transition to parenthood. The aim of the study was to research the meaning of transition to parenthood through the lens of transformative learning theory. Transformative learning theory explains learning through meaning-making of that life experience. In this paper, the spiritual dimension of learning is emphasized. An important part of research methodology included biographical method, using semi-structured interviews before and after the birth of the first child. The research showed that transformative learning occurs in different spheres of life during transition to parenthood. This paper discusses the spiritual dimension of learning, meaning-making and presents results of the research.

Generalized transition state theory. Quantum effects for collinear reactions of hydrogen molecules and isotopically substituted hydrogen molecules

International Nuclear Information System (INIS)

Garrett, B.C.; Truhlar, D.G.

1979-01-01

Canonical variational transition state theory, microcanonical variational transition state theory, and Miller's unified statistical theory were used in an attempt to correct two major deficiencies of the conventional transition state theory. These are: (1) the necessity of extra assumptions to include quantum mechanical tunneling effects and (2) the fundamental assumption that trajectories crossing a dividing surface in phase space proceed directly to products. The accuracy of these approximate methods were tested by performing calculations for several collinear reactions of hydrogen, deuterium, chlorine, or iodine, with five isotopes of hydrogen molecules and comparison of these results with those from accurate quantitative calculations of the reaction probabilities as functions of energy and of the thermal rate constants as functions of temperature. 49 references, 28 figures, 17 tables

Thermal isomerization of azobenzenes: on the performance of Eyring transition state theory

Science.gov (United States)

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.

Variational transition-state theory. Progress report, February 1981-January 1983

International Nuclear Information System (INIS)

Truhlar, D.G.

1983-01-01

During the past two years we have extended the variational transition-state theory in several ways. Especially notable is that we have developed several new methods for calculating tunneling probabilities, including two general techniques applicable to systems with small and large reaction-path curvature. We have tested these methods successfully against accurate quantal calculations, and we have applied them to real systems in three dimensions. We have also developed general algorithms for variational transition state theory calculations on polyatomic systems and we have applied these to the combustion reaction OH + H 2 → H 2 O + H. We have developed and successfully applied a statistical-diabatic theory for state-selected rates. We made a totally ab initio prediction of an absolute chemical reaction rate, for the reaction Mu + H 2 → MuH + H, using an accurate potential energy surface and ethods that we had demonstrated to be reliable by tests against accurate quantal collinear results. This prediction has now been confirmed by unpublished experiments; I believe that this is the first reliable ab initio prediction of a chemical rection rate prior to its measurement. In the rest of this technical progress report we give further details of these and other studies we have carried out in the last two years under this contract

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...... in a natural way. For example, it is shown that for many homogeneous structural transformations the marginal dimensionality is two, so that mean field theory will be valid for real three‐dimensional systems. It is suggested that this simple self‐consistent approach to Landau theory should be incorporated...

Climate change underlies global demographic, genetic, and cultural transitions in pre-Columbian southern Peru.

Science.gov (United States)

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.

Relativistic many-body theory of atomic transitions. The relativistic equation-of-motion approach

International Nuclear Information System (INIS)

Huang, K.

1982-01-01

An equation-of-motion approach is used to develop the relativistic many-body theory of atomic transitions. The relativistic equations of motion for transition matrices are formulated with the use of techniques of quantum-field theory. To reduce the equations of motion to a tractable form which is appropriate for numerical calculations, a graphical method to resolve the complication arising from the antisymmetrization and angular-momentum coupling is employed. The relativistic equation-of-motion method allows an ab initio treatment of correlation and relativistic effects in both closed- and open-shell many-body systems. A special case of the present formulation reduces to the relativistic random-phase approximation

Relativistic many-body theory of atomic transitions: the relativistic equation-of-motion approach

International Nuclear Information System (INIS)

Huang, K.N.

1981-01-01

An equation-of-motion approach is used to develop the relativistic many-body theory of atomic transitions. The relativistic equations of motion for transition matrices are formulated using techniques of quantum field theory. To reduce the equation of motion to a tractable form which is appropriate for numerical calculations, a graphical method is employed to resolve the complication arising from the antisymmetrization and angular momentum coupling. The relativistic equation-of-motion method allows an ab initio treatment of correlation and relativistic effects in both closed- and open-shell many-body systems. A special case of the present formulation reduces to the relativistic random-phase approximation

Kinetics of Hydrogen Radical Reactions with Toluene Including Chemical Activation Theory Employing System-Specific Quantum RRK Theory Calibrated by Variational Transition State Theory.

Science.gov (United States)

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.

The role of demographic compensation theory in incidental take assessments for endangered species

Science.gov (United States)

McGowan, Conor P.; Ryan, Mark R.; Runge, Michael C.; Millspaugh, Joshua J.; Cochrane, Jean Fitts

2011-01-01

Many endangered species laws provide exceptions to legislated prohibitions through incidental take provisions as long as take is the result of unintended consequences of an otherwise legal activity. These allowances presumably invoke the theory of demographic compensation, commonly applied to harvested species, by allowing limited harm as long as the probability of the species' survival or recovery is not reduced appreciably. Demographic compensation requires some density-dependent limits on survival or reproduction in a species' annual cycle that can be alleviated through incidental take. Using a population model for piping plovers in the Great Plains, we found that when the population is in rapid decline or when there is no density dependence, the probability of quasi-extinction increased linearly with increasing take. However, when the population is near stability and subject to density-dependent survival, there was no relationship between quasi-extinction probability and take rates. We note however, that a brief examination of piping plover demography and annual cycles suggests little room for compensatory capacity. We argue that a population's capacity for demographic compensation of incidental take should be evaluated when considering incidental allowances because compensation is the only mechanism whereby a population can absorb the negative effects of take without incurring a reduction in the probability of survival in the wild. With many endangered species there is probably little known about density dependence and compensatory capacity. Under these circumstances, using multiple system models (with and without compensation) to predict the population's response to incidental take and implementing follow-up monitoring to assess species response may be valuable in increasing knowledge and improving future decision making.

On the theory of global population growth

International Nuclear Information System (INIS)

Kapitza, Sergei P

2010-01-01

Ours is an epoch of global demographic revolution, a time of a rapid transition from explosive population growth to a low reproduction level. This, possibly the most momentous change ever witnessed by humankind has, first and foremost, important implications for the dynamics of population. But it also affects billions of people in all aspects of their lives, and it is for this reason that demographic processes have grown into a vast problem, both globally and in Russia. Their fundamental understanding will to a large extent impact the present, the short-term future following the current critical epoch, the stable and uniform global development and its priorities, and indeed global security. Quantitative treatment of historical processes is reached using the phenomenological theory of mankind's population growth. This theory relies on the concepts and methods of physics and its conclusions should take into account the ideas of economics and genetics. (interdisciplinary physics)

Internal conversion coefficients of high multipole transitions: Experiment and theories

International Nuclear Information System (INIS)

Gerl, J.; Vijay Sai, K.; Sainath, M.; Gowrishankar, R.; Venkataramaniah, K.

2008-01-01

A compilation of the available experimental internal conversion coefficients (ICCs), α T , α K , α L , and ratios K/L and K/LM of high multipole (L > 2) transitions for a number of elements in the range 21 ≤ Z ≤ 94 is presented. Our listing of experimental data includes 194 data sets on 110 E3 transitions, 10 data sets on 6 E4 transitions, 11 data sets on 7 E5 transitions, 38 data sets on 21 M3 transitions, and 132 data sets on 68 M4 transitions. Data with less than 10% experimental uncertainty have been selected for comparison with the theoretical values of Hager and Seltzer [R.S. Hager, E.C. Seltzer, Nucl. Data Tables A 4 (1968) 1], Rosel et al. [F. Roesel, H.M. Fries, K. Alder, H.C. Pauli, At. Data Nucl. Data Tables 21 (1978) 91], and BRICC. The relative percentage deviations (%Δ) have been calculated for each of the above theories and the averages (%Δ-bar) are estimated. The Band et al. [I.M. Band, M.B. Trzhaskovskaya, C.W. Nestor Jr., P.O. Tikkanen, S. Raman, At. Data Nucl. Data Tables 81 (2002) 1] tables, using the BRICC interpolation code, are seen to give theoretical ICCs closest to experimental values

Demographic study of two population outbreaks of Elasmoderus wagenknechti (Liebermann) (Orthoptera: Tristiridae) in the transitional desert of Chile.

Science.gov (United States)

Cepeda-Pizarro, Jorge; Vega, Solange; Vásquez, Hernán; Elgueta, Mario; Pizarro-Araya, Jaime

2007-01-01

Under certain environmental conditions, several species of grasshoppers inhabiting rangeland areas (e.g., inter-valleys) of the Chilean transitional desert can irrupt demographically. One of them is Elasmoderus wagenknechti (Liebermann), an endemic species. We studied two outbreaks occurred in 1996 and 1999. The objectives of the research were to (i) estimate some demographic parameters associated with the aforementioned events, and (ii) compare between them the population parameters. The parameters we studied were density (ind/m(2)), sexual proportion, female fertility (i.e., eggs/female), and the relationship eggs/female versus female size. Density (ind/m(2)) ranged from 0.2 to 0.4 in 1996 and from 0.5 to 0.6 in 1999. ANOVA-tests registered differences in density among study sites and between years. In some of the study sites, females were more abundant than males (e.g., Lomas del Sauce). Females fertility ranged from 27 to 39 eggs per female, with significant differences among sites in 1996 but not in 1999. For females of 30-50 mm body size, a linear relationship was detected between egg number/female and body size. It is concluded that the E. wagenknechti outbreaks are site-specific in the study area and that the demographic parameters examined show a high variability among sites and between events.

Comparison of a low- to high-confinement transition theory with experimental data from DIII-D.

Science.gov (United States)

Guzdar, P N; Kleva, R G; Groebner, R J; Gohil, P

2002-12-23

From our recent theory based on the generation of shear flow and field in finite beta plasmas, the criterion for bifurcation from low to high confinement mode yields a critical parameter proportional to T(e)/square root (L(n)), where T(e) is the electron temperature and L(n) is the density scale length. The predicted threshold shows very good agreement with edge measurements on discharges undergoing low-to-high transitions in DIII-D. The observed differences in the transitions with the reversal of the toroidal magnetic field are reconciled in terms of this critical parameter. The theory also provides an explanation for pellet injection H modes in DIII-D, thereby unifying unconnected methods for accomplishing the transition.

Understanding the Demographic Differences in Neighborhood Walking Supports.

Science.gov (United States)

Carlson, Susan A; Watson, Kathleen B; Paul, Prabasaj; Schmid, Thomas L; Fulton, Janet E

2017-04-01

Information about how presence and usefulness of neighborhood supports for walking differs by demographic characteristics can help guide community strategies to promote walking. Reported presence and usefulness of neighborhood supports (shops, transit stops, sidewalks, parks, interesting things to look at, well-lit at night, low crime rate, and cars following speed limit) were examined in 3973 U.S. adults who completed the 2014 SummerStyles survey. Percentage reporting neighborhood supports as present ranged from 25.3% (SE = 0.8) for interesting things to 55.8% (SE = 1.0) for low crime rate. Percentage who reported a support as useful ranged from 24.6% (SE = 1.4) for transit stops to 79.0% (SE = 1.1) for sidewalks among those with the support. This percentage ranged from 13.4% (SE = 0.8) for transit stops to 52.8% (SE = 1.1) for shops among those without the support. One or more demographic differences were observed for the presence of each support, and the presence of all supports differed by education and metro status. Demographic patterns were less clear when examining usefulness and patterns often differed by support type and presence. Presence and usefulness of neighborhood supports for walking can differ by type and demographic characteristics. Recognizing these difference can help communities plan and implement strategies to promote walking.

Probabilistic physical characteristics of phase transitions at highway bottlenecks: incommensurability of three-phase and two-phase traffic-flow theories.

Science.gov (United States)

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.

Chaos Theory as a Model for Life Transitions Counseling: Nonlinear Dynamics and Life's Changes

Science.gov (United States)

Bussolari, Cori J.; Goodell, Judith A.

2009-01-01

Chaos theory is presented for counselors working with clients experiencing life transitions. It is proposed as a model that considers disorder, unpredictability, and lack of control as normal parts of transition processes. Nonlinear constructs from physics are adapted for use in counseling. The model provides a method clients can use to…

Mean-field theory for a ferroelectric transition

International Nuclear Information System (INIS)

Dobry, A.; Greco, A.; Stachiotti, M.

1990-01-01

For the treatment of anharmonic models of solids presenting structural transitions, a commonly used approximation is that of self-consistent phonons. Rather than the usual site decoupling, this mean-field theory is based on decoupling of modes in reciprocal space. A self-consistent phonon approximation for the non-linear polarizability model is developed in this work. The model describes the dynamical properties of ferroelectric materials. Phase diagrams as a function of relevant model parameters are presented. An analysis is made of critical behaviour and it is shown that the approximation leads to the same anomalies found in other models. (Author). 9 refs., 3 figs

Demographic and Motivation Differences Among Online Sex Offenders by Type of Offense: An Exploration of Routine Activities Theories.

Science.gov (United States)

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.

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.

Demographic Modelling in Weed Biocontrol

Science.gov (United States)

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...

Temperature-dependent study of isotropic-nematic transition for a Gay-Berne fluid using density-functional theory

International Nuclear Information System (INIS)

Singh, Ram Chandra

2007-01-01

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

Wigner's dynamical transition state theory in phase space : classical and quantum

NARCIS (Netherlands)

Waalkens, Holger; Schubert, Roman; Wiggins, Stephen

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

TOPICAL PROBLEMS: The phenomenological theory of world population growth

Science.gov (United States)

Kapitza, Sergei P.

1996-01-01

Of all global problems world population growth is the most significant. Demographic data describe this process in a concise and quantitative way in its past and present. Analysing this development it is possible by applying the concepts of systems analysis and synergetics, to work out a mathematical model for a phenomenological description of the global demographic process and to project its trends into the future. Assuming self-similarity as the dynamic principle of development, growth can be described practically over the whole of human history, assuming the growth rate to be proportional to the square of the number of people. The large parameter of the theory and the effective size of a coherent population group is of the order of 105 and the microscopic parameter of the phenomenology is the human lifespan. The demographic transition — a transition to a stabilised world population of some 14 billion in a foreseeable future — is a systemic singularity and is determined by the inherent pattern of growth of an open system, rather than by the lack of resources. The development of a quantitative nonlinear theory of the world population is of interest for interdisciplinary research in anthropology and demography, history and sociology, for population genetics and epidemiology, for studies in evolution of humankind and the origin of man. The model also provides insight into the stability of growth and the present predicament of humankind, and provides a setting for discussing the main global problems.

Theory of direct-interband-transition line shapes based on Mori's method

International Nuclear Information System (INIS)

Sam Nyung Yi; Jai Yon Ryu; Ok Hee Chung; Joung Young Sug; Sang Don Choi; Yeon Choon Chung

1987-01-01

A theory of direct interband optical transition in the electron-phonon system is introduced on the basis of the Kubo formalism and by using Mori's method of calculation. The line shape functions are introduced in two different ways and are compared with those obtained by Choi and Chung based on Argyres and Sigel's projection technique

Theory of high-T sub c superconductivity based on the fermion-condensation quantum phase transition

CERN Document Server

Amusia, M Ya; Shaginyan, V R

2001-01-01

A theory of high temperature superconductivity based on the combination of the fermion-condensation quantum phase transition and the conventional theory of superconductivity is presented. This theory describes maximum values of the superconducting gap which can be as big as DELTA sub 1 approx 0.1 epsilon sub F , with epsilon sub F being the Fermi level. It is shown that the critical temperature 2T sub c approx = DELTA sub 1. If there exists the pseudogap above T sub c then 2T* approx = DELTA sub 1 , and T* is the temperature at which the pseudogap vanished. A discontinuity in the specific heat at T sub c is calculated. The transition from conventional superconductors to high-T sub c ones as a function of the doping level is investigated

Vibrational transitions in hydrogen bonded bimolecular complexes – A local mode perturbation theory approach to transition frequencies and intensities

DEFF Research Database (Denmark)

Mackeprang, Kasper; Kjærgaard, Henrik Grum

2017-01-01

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...

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.

Deconfinement phase transition in the Hamiltonian approach to Yang–Mills theory in Coulomb gauge

Directory of Open Access Journals (Sweden)

Reinhardt H.

2014-04-01

Full Text Available Recent results obtained for the deconfinement phase transition within the Hamiltonian approach to Yang–Mills theory are reviewed. Assuming a quasiparticle picture for the grand canonical gluon ensemble the thermal equilibrium state is found by minimizing the free energy with respect to the quasi-gluon energy. The deconfinement phase transition is accompanied by a drastic change of the infrared exponents of the ghost and gluon propagators. Above the phase transition the ghost form factor remains infrared divergent but its infrared exponent is approximately halved. The gluon energy being infrared divergent in the confined phase becomes infrared finite in the deconfined phase. Furthermore, the effective potential of the order parameter for confinement is calculated for SU(N Yang–Mills theory in the Hamiltonian approach by compactifying one spatial dimension and using a background gauge fixing. In the simplest truncation, neglecting the ghost and using the ultraviolet form of the gluon energy, we recover the Weiss potential. From the full non-perturbative potential (with the ghost included we extract a critical temperature of the deconfinement phase transition of 269 MeV for the gauge group SU(2 and 283 MeV for SU(3.

Quantum Debye-Hueckel theory and the possible plasma phase transition

International Nuclear Information System (INIS)

Baker, G. Jr.

1998-01-01

In this paper the author first sketches the calculation of the pressure of a neutral, ion-electron gas as an expansion in powers of the electron charge, e, by means of the Matsubara, finite-temperature, many-body, perturbation theory. He then goes on to derive the Debye-Hue term and other equations to support his contentions. His results support but do not prove the existence of a phase transition

Short review on contemporary state of X-ray transition radiation theory

International Nuclear Information System (INIS)

Garibyan, G.M.

1977-01-01

The main properties of the X-ray transition radiation and the prehistory of the development of this phenomenon are given. The radiation produced when a charged particle passes through a regular and irregular stack of plates, the influence of the multiple scattering on the radiation as well as the microscopic theory of this phenomenon are considered

Liquid-Vapor Phase Transition: Thermomechanical Theory, Entropy Stable Numerical Formulation, and Boiling Simulations

Science.gov (United States)

2015-05-01

vapor bubbles may generate near blades [40]. This is the phenomenon of cavitation and it is still a limiting factor for ship propeller design. Phase...van der Waals theory with hydrodynamics [39]. The fluid equations based on the van der Waals theory are called the Navier-Stokes-Korteweg equations... cavitating flows, the liquid- vapor phase transition induced by pressure variations. A potential challenge for such a simulation is a proper design of open

Childhood obesity in transition zones: an analysis using structuration theory.

Science.gov (United States)

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.

Changes in physical activity during the retirement transition: a theory-based, qualitative interview study.

Science.gov (United States)

McDonald, Suzanne; O'Brien, Nicola; White, Martin; Sniehotta, Falko F

2015-02-21

There are considerable inter-individual differences in the direction and degree of change in physical activity (PA) levels during the retirement transition. There is currently a limited theoretical understanding of how these differences can be explained. This study aimed to explore and compare perceptions about how theory-based factors influence PA change during the transition from employment to retirement among individuals approaching retirement and recently retired. Theory-based, one-to-one, semi-structured interviews were conducted with a purposive sample of 28 adults (15 retired) within 24 months of retirement. Participants were sampled to reflect a diverse range of socio-economic and occupational backgrounds. The interview was based on the 12 domains within the Theory Domain Framework and designed to elicit anticipated or experienced retirement-related changes in PA behaviour and perceived determinants. Interview transcripts were analysed using Framework analysis to explore intra- and inter-individual perceptions of how PA changes after retirement and the factors which may influence this change. The majority of participants perceived retirement to be related to an increase in PA levels. Four themes emerged from the data regarding factors perceived to influence changes in PA behaviour after retirement: (1) resources for PA; (2) structure of daily life in retirement; (3) opportunities for PA; and (4) transitional PA phases after retirement. Retirement is associated with a number of inter-related changes and opportunities which can have a positive or negative impact on PA behaviour. The influence of these factors does not appear to be static and may change over time. A number of different transitional phases may be experienced after leaving work and each phase may have a differential impact on PA behaviour. The findings of this qualitative study contribute to the theoretical understanding of PA change during the retirement transition. Each post-retirement PA

Possible higher order phase transition in large-N gauge theory at finite temperature

Energy Technology Data Exchange (ETDEWEB)

Nishimura, Hiromichi

2017-08-07

We analyze the phase structure of SU(¥) gauge theory at finite temperature using matrix models. Our basic assumption is that the effective potential is dominated by double-trace terms for the Polyakov loops. As a function of the temperature, a background field for the Polyakov loop, and a quartic coupling, it exhibits a universal structure: in the large portion of the parameter space, there is a continuous phase transition analogous to the third-order phase transition of Gross,Witten and Wadia, but the order of phase transition can be higher than third. We show that different confining potentials give rise to drastically different behavior of the eigenvalue density and the free energy. Therefore lattice simulations at large N could probe the order of phase transition and test our results. Critical

Ugly Facts and Fancy Theories: Children and Youth during the Transition. Innocenti Occasional Papers Economic Policy Series, Number 47. Special Subseries: Economies in Transition.

Science.gov (United States)

Cornia, Giovanni Andrea

This is a report sponsored by UNICEF on the effects of economic and political transition in Europe, particularly Eastern Europe, on young children and adolescents. The economic theories and changes in labor and markets which have characterized European transitions in the past few years have paid little attention to issues of poverty and child…

Phase transition in a quark-gluon plasma and hydrodynamic theory

International Nuclear Information System (INIS)

Chernavskaya, O.D.; Chernavskij, D.S.

1988-01-01

A wide range of problem concerning the phase transition of a quark-gluon plasma to the hadron matter is considered in connection with the hardronization problem within the frame of the hydrodynamical theory of ultra-relativistic collisions. A short review of the present hadron models and possible mechanisms of thermalization is given. The character of the phase transition within the bag model is analysed, effects of the surface interaction result in a nontrivial character of the phase transition: the metastable states of matter become possible. The review of the possible scenaria of hadronization of the cooling hydrodynamical matter is given, the choice between them is determined by a kinetic analysis. The systems with the energy density near the critical point (∼ 4 GeV/Fm 3 ) are shown to be hadronized by the mechanism based on a strong plasma supercooling (with a considerable transverse momentum increase). The traditional hadronization mechanism (mixed phase) is preferable for more hot systems. Theoretical estimations are compared with the JACEE (cosmic rays) data

Application of renormalization group theory to the large-eddy simulation of transitional boundary layers

Science.gov (United States)

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.

Effective field theory with differential operator technique for dynamic phase transition in ferromagnetic Ising model

International Nuclear Information System (INIS)

Kinoshita, Takehiro; Fujiyama, Shinya; Idogaki, Toshihiro; Tokita, Masahiko

2009-01-01

The non-equilibrium phase transition in a ferromagnetic Ising model is investigated by use of a new type of effective field theory (EFT) which correctly accounts for all the single-site kinematic relations by differential operator technique. In the presence of a time dependent oscillating external field, with decrease of the temperature the system undergoes a dynamic phase transition, which is characterized by the period averaged magnetization Q, from a dynamically disordered state Q = 0 to the dynamically ordered state Q ≠ 0. The results of the dynamic phase transition point T c determined from the behavior of the dynamic magnetization and the Liapunov exponent provided by EFT are improved than that of the standard mean field theory (MFT), especially for the one dimensional lattice where the standard MFT gives incorrect result of T c = 0 even in the case of zero external field.

QED theory of multiphoton transitions in atoms and ions

Science.gov (United States)

Zalialiutdinov, Timur A.; Solovyev, Dmitry A.; Labzowsky, Leonti N.; Plunien, Günter

2018-03-01

This review surveys the quantum theory of electromagnetic radiation for atomic systems. In particular, a review of current theoretical studies of multiphoton processes in one and two-electron atoms and highly charged ions is provided. Grounded on the quantum electrodynamics description the multiphoton transitions in presence of cascades, spin-statistic behaviour of equivalent photons and influence of external electric fields on multiphoton in atoms and anti-atoms are discussed. Finally, the nonresonant corrections which define the validity of the concept of the excited state energy levels are introduced.

Complexity and demographic explanations of cumulative culture

NARCIS (Netherlands)

Querbes, A.; Vaesen, K.; Houkes, W.N.

2014-01-01

Formal models have linked prehistoric and historical instances of technological change (e.g., the Upper Paleolithic transition, cultural loss in Holocene Tasmania, scientific progress since the late nineteenth century) to demographic change. According to these models, cumulation of technological

Second order phase transition in two dimensional sine-Gordon field theory - lattice model

International Nuclear Information System (INIS)

Babu Joseph, K.; Kuriakose, V.C.

1978-01-01

Two dimensional sine-Gordon (SG) field theory on a lattice is studied using the single-site basis variational method of Drell and others. The nature of the phase transition associated with the spontaneous symmetry breakdown in a SG field system is clarified to be of second order. A generalisation is offered for a SG-type field theory in two dimensions with a potential of the form [cossup(n)((square root of lambda)/m)phi-1].(author)

Theory for Explaining and Comparing the Dynamics of Education in Transitional Processes

Science.gov (United States)

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…

Characterization of Phase Transition in Heisenberg Fluids from Density Functional Theory

International Nuclear Information System (INIS)

Li Liangsheng; Li Li; Chen Xiaosong

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 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* = ρσ 3 = 0.224 and the reduced temperature T* = kT/ element of = 1.87 (σ is the diameter of Heisenberg hard sphere and element of is the coupling constant).

Mott-Hubbard transition and Anderson localization: A generalized dynamical mean-field theory approach

International Nuclear Information System (INIS)

Kuchinskii, E. Z.; Nekrasov, I. A.; Sadovskii, M. V.

2008-01-01

The DOS, the dynamic (optical) conductivity, and the phase diagram of a strongly correlated and strongly disordered paramagnetic Anderson-Hubbard model are analyzed within the generalized dynamical mean field theory (DMFT + Σ approximation). Strong correlations are taken into account by the DMFT, and disorder is taken into account via an appropriate generalization of the self-consistent theory of localization. The DMFT effective single-impurity problem is solved by a numerical renormalization group (NRG); we consider the three-dimensional system with a semielliptic DOS. The correlated metal, Mott insulator, and correlated Anderson insulator phases are identified via the evolution of the DOS and dynamic conductivity, demonstrating both the Mott-Hubbard and Anderson metal-insulator transition and allowing the construction of the complete zero-temperature phase diagram of the Anderson-Hubbard model. Rather unusual is the possibility of a disorder-induced Mott insulator-to-metal transition

Testing the renormalisation group theory of cooperative transitions at the lambda point of helium

Science.gov (United States)

Lipa, J. A.; Li, Q.; Chui, T. C. P.; Marek, D.

1988-01-01

The status of high resolution tests of the renormalization group theory of cooperative phase transitions performed near the lambda point of helium is described. The prospects for performing improved tests in space are discussed.

Refinement of the gross theory of nuclear {beta}-decay, and hindrance of the first-forbidden transition of rank 1

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)

Group theoretical arguments on the Landau theory of second-order phase transitions applied to the phase transitions in some liquid crystals

International Nuclear Information System (INIS)

Rosciszewski, K.

1979-01-01

The phase transitions between liquids and several of the simplest liquid crystalline phases (nematic, cholesteric, and the simplest types of smectic A and smectic C) were studied from the point of view of the group-theoretical arguments of Landau theory. It was shown that the only possible candidates for second-order phase transitions are those between nematic and smectic A, between centrosymmetric nematic and smectic C and between centrosymmetric smectic A and smectic C. Simple types of density functions for liquid crystalline phases are proposed. (author)

Analyses of kinetic glass transition in short-range attractive colloids based on time-convolutionless mode-coupling theory.

Science.gov (United States)

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.

Matter in transition

International Nuclear Information System (INIS)

Anderson, Lara B.; Gray, James; Raghuram, Nikhil; Taylor, Washington

2016-01-01

We explore a novel type of transition in certain 6D and 4D quantum field theories, in which the matter content of the theory changes while the gauge group and other parts of the spectrum remain invariant. Such transitions can occur, for example, for SU(6) and SU(7) gauge groups, where matter fields in a three-index antisymmetric representation and the fundamental representation are exchanged in the transition for matter in the two-index antisymmetric representation. These matter transitions are realized by passing through superconformal theories at the transition point. We explore these transitions in dual F-theory and heterotic descriptions, where a number of novel features arise. For example, in the heterotic description the relevant 6D SU(7) theories are described by bundles on K3 surfaces where the geometry of the K3 is constrained in addition to the bundle structure. On the F-theory side, non-standard representations such as the three-index antisymmetric representation of SU(N) require Weierstrass models that cannot be realized from the standard SU(N) Tate form. We also briefly describe some other situations, with groups such as Sp(3), SO(12), and SU(3), where analogous matter transitions can occur between different representations. For SU(3), in particular, we find a matter transition between adjoint matter and matter in the symmetric representation, giving an explicit Weierstrass model for the F-theory description of the symmetric representation that complements another recent analogous construction.

Fluctuation effects in first-order phase transitions: Theory and model for martensitic transformations

DEFF Research Database (Denmark)

Lindgård, Per-Anker; Mouritsen, Ole G.

1990-01-01

We discuss central questions in weak, first-order structural transitions by means of a magnetic analog model. A theory including fluctuation effects is developed for the model, showing a dynamical response with softening, fading modes and a growing central peak. The model is also analyzed by a two......-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...

Transition state theory approach to polymer escape from a one dimensional potential well.

Science.gov (United States)

Mökkönen, Harri; Ikonen, Timo; Ala-Nissila, Tapio; Jónsson, Hannes

2015-06-14

The rate of escape of an ideal bead-spring polymer in a symmetric double-well potential is calculated using transition state theory (TST) and the results compared with direct dynamical simulations. The minimum energy path of the transitions becomes flat and the dynamics diffusive for long polymers making the Kramers-Langer estimate poor. However, TST with dynamical corrections based on short time trajectories started at the transition state gives rate constant estimates that agree within a factor of two with the molecular dynamics simulations over a wide range of bead coupling constants and polymer lengths. The computational effort required by the TST approach does not depend on the escape rate and is much smaller than that required by molecular dynamics simulations.

The Ebb and Flow of Filipino First-Time Fatherhood Transition Space: A Grounded Theory Study.

Science.gov (United States)

Villamor, Neil Jupiter E; de Guzman, Allan B; Matienzo, Evangeline T

2016-11-01

Fatherhood, as a developmental process, is both a human experience and a text that needs to be read. For developing nations like the Philippines, little is known about the process undergone by first-time fathers on their transition to fatherhood, and how nurses can play a significant role in assisting them. This grounded theory study purported to conceptualize the multifaceted process of transition from the lens of Filipino first-time fathers' lived experiences. A total of 20 first-time fathers from Metro Manila, Philippines, were purposively selected to take part in an individual, semistructured, and in-depth interview. The Glaserian (classical) method of analysis was specifically used, and field texts were inductively analyzed using a repertory grid. Member checking and correspondence were done to validate the findings of the study. Six surfacing stages emerged relative to the process of transition. Interestingly, The B.R.I.D.G.E. Theory of First-Time Fatherhood Transition Space describes how these fathers progress from the beholding, reorganizing, inhibiting, delivering, grasping, and embracing phases toward successful transition. This emerged theoretical model can be used in framing health care programs where the needs of fathers during this period are met and addressed. Finally, it can also be used in guiding nurses in their provision of a more empathetic care for first-time fathers. © The Author(s) 2015.

[Dying well seen in the light of self-transcendence and transition : two theories of care helpful to nurses].

Science.gov (United States)

Laporte, Pauline; Vonarx, Nicolas

2016-06-01

Accompanying a dying person up to and at the actual moment of death is a duty that often leaves carers at a loss. We shall show how far theoretical nursing knowledge can help practitioners who accompany the end of life by applying two theories of care : Reed’s theory of self-transcendence and Meleis’s theory of transition. Our interpretation of the theory of self-transcendence designates three points of reference in the concept of dying well. The first relates to the overtures prompted by the vulnerability that the context of dying inspires. The second concerns the capacity of the patient to summon up intrapersonal, interpersonal and transpersonal strategies, and the third considers the benefits when self-transcendence is achieved. The theory of transition similarly presents three points of reference. The first is based on informing the patient about palliative care and telling him or her the truth about the prognosis. The second relates to coordinating the interprofessional team that is looking after the dying person. The last criterion is that the palliative care should be started at a suitable moment. This makes it possible to educate a patient who wishes to die at home and thus create an environment favourable to the transition.

Transition-state theory predicts clogging at the microscale

Science.gov (United States)

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.

Phase transitions in the argon, krypton and xenon in generalized Van der Waals theory

International Nuclear Information System (INIS)

Cavalcanti, H.M.

1977-01-01

Fluid-solid like phase transitions for three monoatomic substances, argon, krypton and xenon are treated, using the extension of the Van der Waals theory to the crystalline state. The method utilized is based on 'Maxwell construction' of identical areas [pt

Development of a (4-ε)-dimensional theory for the density of states of a disordered system near the Anderson transition

International Nuclear Information System (INIS)

Suslov, Igor' M

1998-01-01

The calculation of the density of states for the Schroedinger equation with a Gaussian random potential is equivalent to the problem of a second-order transition with a 'wrong' sign for the coefficient of the quartic term in the Ginzburg-Landau Hamiltonian. The special role of the dimension d = 4 for such a Hamiltonian can be seen from different viewpoints but is fundamentally determined by the renormalizability of the theory. The construction of an ε expansion in direct analogy with the phase-transition theory gives rise to the problem of a 'spurious' pole. To solve this problem, a proper treatment of the factorial divergency of the perturbation series is necessary. Simplifications arising in high dimensions can be used for the development of a (4-ε)-dimensional theory, but this requires successive consideration of four types of theories: a nonrenormalizable theories for d > 4, nonrenormalizable and renormalizable theories in the logarithmic situation (d = 4), and a super-renormalizable theories for d < 4. An approximation is found for each type of theory giving asymptotically exact results. In the (4-ε)-dimensional theory, the terms of leading order in 1/ε are only retained for N∼1 (N is the order of the perturbation theory) while all degrees of 1/ε are essential for large N in view of the fast growth of their coefficients. The latter are calculated in the leading order in N from the Callan-Symanzik equation with the results of Lipatov method used as boundary conditions. The qualitative effect is the same in all four cases and consists in a shifting of the phase transition point in the complex plane. This results in the elimination of the 'spurious' pole and in regularity of the density of states for all energies. A discussion is given of the calculation of high orders of perturbation theory and a perspective of the ε expansion for the problem of conductivity near the Anderson transition. (reviews of topical problems)

Demographics, political power and economic growth.

Science.gov (United States)

Holtz-eakin, D

1993-01-01

"Growth theory may be used to predict the response of saving, capital formation, and output growth to large demographic shifts. Such large shifts would also be expected to alter the demand for government services and the desired levels of taxation in the population. This paper extends the overlapping-generations model of economic growth to predict the evolution of government tax and spending policy through the course of a major demographic shift. Simulations suggest that this approach may yield valuable insights into the evolution of policy in the United States and other industrialized economies." excerpt

Economic and demographic assumptions of the public pension insurance system functioning

Directory of Open Access Journals (Sweden)

Đukić Gordana

2016-01-01

Full Text Available The demographic transition is characterized by a decline in birth rates and fertility on the one hand, and an intense increase in the number of old people on the other hand. The intensity of demographic ageing is characteristic of certain countries, being more expressed in developed countries. In such a situation, negative economic consequences arise in the context of unemployment, due to a decreased number of young population and lower participation in the labour market, as well as in the domains of savings, capital market, health protection, pension system and institutional development. These consequences can be mitigated by the application of appropriate economic transition and macroeconomic policy. Demographic tendencies have a great impact on changes in the values of the pension system parameters. The dependence rate indicating the relation between the number of employed people and the number of pensioners, and the average replacement rate representing the relation between the average wage and average pension, are directly dependent on demographic changes and they directly affect the sustainability of the public pension insurance system.

Multiconfiguration pair-density functional theory: barrier heights and main group and transition metal energetics.

Science.gov (United States)

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.

An aggregate method to calibrate the reference point of cumulative prospect theory-based route choice model for urban transit network

Science.gov (United States)

Zhang, Yufeng; Long, Man; Luo, Sida; Bao, Yu; Shen, Hanxia

2015-12-01

Transit route choice model is the key technology of public transit systems planning and management. Traditional route choice models are mostly based on expected utility theory which has an evident shortcoming that it cannot accurately portray travelers' subjective route choice behavior for their risk preferences are not taken into consideration. Cumulative prospect theory (CPT), a brand new theory, can be used to describe travelers' decision-making process under the condition of uncertainty of transit supply and risk preferences of multi-type travelers. The method to calibrate the reference point, a key parameter to CPT-based transit route choice model, determines the precision of the model to a great extent. In this paper, a new method is put forward to obtain the value of reference point which combines theoretical calculation and field investigation results. Comparing the proposed method with traditional method, it shows that the new method can promote the quality of CPT-based model by improving the accuracy in simulating travelers' route choice behaviors based on transit trip investigation from Nanjing City, China. The proposed method is of great significance to logical transit planning and management, and to some extent makes up the defect that obtaining the reference point is solely based on qualitative analysis.

Random walk theory and exchange rate dynamics in transition economies

Directory of Open Access Journals (Sweden)

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.

Comparison of 3D Classical Trajectory and Transition-State Theory Reaction Cross Sections

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Koeppl, G. W.; Karplus, Martin

1970-10-01

Although there is excellent agreement for a system such as H+H{sub 2} --> H{sub 2}+H, in which both the potential and the particle masses are symmetric, significant deviations occur for more asymmetric reactions. A detailed analysis show that the calculated differences are from the violation of two assumptions of transition-state theory.

Meta-orbital transition in heavy-fermion systems. Analysis by dynamical mean field theory and self-consistent renormalization theory of orbital fluctuations

International Nuclear Information System (INIS)

Hattori, Kazumasa

2010-01-01

We investigate a two-orbital Anderson lattice model with Ising orbital intersite exchange interactions on the basis of a dynamical mean field theory combined with the static mean field approximation of intersite orbital interactions. Focusing on Ce-based heavy-fermion compounds, we examine the orbital crossover between two orbital states, when the total f-electron number per site n f is ∼1. We show that a 'meta-orbital' transition, at which the occupancy of two orbitals changes steeply, occurs when the hybridization between the ground-state f-electron orbital and conduction electrons is smaller than that between the excited f-electron orbital and conduction electrons at low pressures. Near the meta-orbital critical end point, orbital fluctuations are enhanced and couple with charge fluctuations. A critical theory of meta-orbital fluctuations is also developed by applying the self-consistent renormalization theory of itinerant electron magnetism to orbital fluctuations. The critical end point, first-order transition, and crossover are described within Gaussian approximations of orbital fluctuations. We discuss the relevance of our results to CeAl 2 , CeCu 2 Si 2 , CeCu 2 Ge 2 , and related compounds, which all have low-lying crystalline-electric-field excited states. (author)

THE DYNAMIC OF THE DEMOGRAPHIC COMPONENT OF THE OLT AND JIU BORDERED SUB-CARPATHIANS IN THE TRANSITION PERIOD – AS A PREMISE OF THE ECONOMICAL AND SOCIAL DEVELOPMENT

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Simona MĂLĂESCU

2008-05-01

Full Text Available In the transition period, the Sub-Carpathians between Olt and Jiu were characterised by a reduced growth of the demographic potential, but especialy by a large mobility due to the socio-economical development and the balance between the rural and urban environment. From a spatial perspective, the Northern frame has reduced its demographic potential in the last 17 years, even more than the rural dorsal between the two bordering cities. Overall, the two extremities have increased their demographic potential, even if the evolutional tendencies have changed along the 17 years.The „centrality” degree and the vicinity of the capital and of the E 70 highway, determine, in the case of Râmnicu Vâlcea, a much higher territorial demographic “binding capacity”. Although still within the upper echelons from the perspective of the socio-economical development indicators, and moreover from that of the demographic resource descriptors (alphabetization indices, etc., the studied perimeter is in a constant demographic potential reduction process (proportionally the same with the distance towards the bordering urban center, firstly of the young one (atracted by the two urbane centers and secondly of the young and qualified –in general (rural and urban –in the benefit of the country’s main urban centers and especially the capital.

The buckling transition of two-dimensional elastic honeycombs: numerical simulation and Landau theory

International Nuclear Information System (INIS)

Jagla, E A

2004-01-01

I study the buckling transition under compression of a two-dimensional, hexagonal, regular elastic honeycomb. Under isotropic compression, the system buckles to a configuration consisting of a unit cell containing four of the original hexagons. This buckling pattern preserves the sixfold rotational symmetry of the original lattice but is chiral, and can be described as a combination of three different elemental distortions in directions rotated by 2π/3 from each other. Non-isotropic compression may induce patterns consisting of a single elemental distortion or a superposition of two of them. The numerical results compare very well with the outcome of a Landau theory of second-order phase transitions

Modern theories of phase transitions

International Nuclear Information System (INIS)

Rajaraman, R.

1979-01-01

Modern applications of the ideas of phase transitions to nuclear systems and the modern techniques as applied to familiar phase transitions in solid-state physics are discussed with illustrations. The phenomenon of pion condensation in nuclei and neutron stars, is presented as an example of phase transitions in nuclear systems. The central physical ideas behind this subject as well as techniques used to tackle it are broadly summarised. It is pointed out that unlike familiar examples of ferromagnetism or superconductivity, the order parameter here has spatial variation even in the ground state. Possible experimental consequences are discussed. As an example of the second category, the use of renormalisation group techniques in solid state physics is reviewed. The basic idea behind the renormalisation group in the infra-red (thermodynamic) limit is presented. The observed universality and scaling of critical exponents in second order phase transitions is explained in a model-independent way. (auth.)

Design theory of full face rock tunnel boring machine transition cutter edge angle and its application

Science.gov (United States)

Zhang, Zhaohuang; Meng, Liang; Sun, Fei

2013-05-01

At present, the inner cutters of a full face rock tunnel boring machine (TBM) and transition cutter edge angles are designed on the basis of indentation test or linear grooving test. The inner and outer edge angles of disc cutters are characterized as symmetric to each other with respect to the cutter edge plane. This design has some practical defects, such as severe eccentric wear and tipping, etc. In this paper, the current design theory of disc cutter edge angle is analyzed, and the characteristics of the rock-breaking movement of disc cutters are studied. The researching results show that the rotational motion of disc cutters with the cutter head gives rise to the difference between the interactions of inner rock and outer rock with the contact area of disc cutters, with shearing and extrusion on the inner rock and attrition on the outer rock. The wear of disc cutters at the contact area is unbalanced, among which the wear in the largest normal stress area is most apparent. Therefore, a three-dimensional model theory of rock breaking and an edge angle design theory of transition disc cutter are proposed to overcome the flaws of the currently used TBM cutter heads, such as short life span, camber wearing, tipping. And a corresponding equation is established. With reference to a specific construction case, the edge angle of the transition disc cutter has been designed based on the theory. The application of TBM in some practical project proves that the theory has obvious advantages in enhancing disc cutter life, decreasing replacement frequency, and making economic benefits. The proposed research provides a theoretical basis for the design of TBM three-dimensional disc cutters whose rock-breaking operation time can be effectively increased.

Field theory of absorbing phase transitions with a non-diffusive conserved field

International Nuclear Information System (INIS)

Pastor-Satorras, R.; Vespignani, A.

2000-04-01

We investigate the critical behavior of a reaction-diffusion system exhibiting a continuous absorbing-state phase transition. The reaction-diffusion system strictly conserves the total density of particles, represented as a non-diffusive conserved field, and allows an infinite number of absorbing configurations. Numerical results show that it belongs to a wide universality class that also includes stochastic sandpile models. We derive microscopically the field theory representing this universality class. (author)

Critical temperature for shape transition in hot nuclei within covariant density functional theory

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Zhang, W.; Niu, Y. F.

2018-05-01

Prompted by the simple proportional relation between critical temperature for pairing transition and pairing gap at zero temperature, we investigate the relation between critical temperature for shape transition and ground-state deformation by taking even-even Cm-304286 isotopes as examples. The finite-temperature axially deformed covariant density functional theory with BCS pairing correlation is used. Since the Cm isotopes are the newly proposed nuclei with octupole correlations, we studied in detail the free energy surface, the Nilsson single-particle (s.p.) levels, and the components of s.p. levels near the Fermi level in 292Cm. Through this study, the formation of octupole equilibrium is understood by the contribution coming from the octupole driving pairs with Ω [N ,nz,ml] and Ω [N +1 ,nz±3 ,ml] for single-particle levels near the Fermi surfaces as it provides a good manifestation of the octupole correlation. Furthermore, the systematics of deformations, pairing gaps, and the specific heat as functions of temperature for even-even Cm-304286 isotopes are discussed. Similar to the relation between the critical pairing transition temperature and the pairing gap at zero temperature Tc=0.6 Δ (0 ) , a proportional relation between the critical shape transition temperature and the deformation at zero temperature Tc=6.6 β (0 ) is found for both octupole shape transition and quadrupole shape transition for the isotopes considered.

Socio-demographic predictors of sleep complaints in indigenous Siberians with a mixed economy.

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Wilson, Hannah J; Klimova, Tatiana M; Knuston, Kristen L; Fedorova, Valentina I; Fedorov, Afanasy; Yegorovna, Baltakhinova M; Leonard, William R

2015-08-01

Socio-demographic indicators closely relate to sleep in industrialized populations. However we know very little about how such factors impact sleep in populations undergoing industrialization. Within populations transitioning to the global economy, the preliminary evidence has found an inconsistent relationship between socio-demographics and sleep complaints across countries and social strata. Surveys were conducted on a sample of rural Sakha (Yakut) adults (n = 168) during the autumn of 2103 to assess variation in socio-demographics and sleep complaints, including trouble sleeping and daytime sleepiness. Socio-demographic variables included age, gender, socioeconomic measures, and markers of traditional/market-based lifestyle. We tested whether the socio-demographic variables predicted sleep complaints using bivariate analyses and multiple logistic regressions. Trouble sleeping was reported by 18.5% of the participants and excessive daytime sleepiness (EDS) by 17.3%. Trouble sleeping was significantly predicted by older age, female gender, and mixing traditional and market-based lifestyles. EDS was not significantly predicted by any socio-demographic variable. These findings support the few large-scale studies that found inconsistent relationships between measures of socioeconomic status and sleep complaints in transitioning populations. Employing a mix of traditional and market-based lifestyles may leave Sakha in a space of vulnerability, leading to trouble sleeping. © 2015 Wiley Periodicals, Inc.

Chaotic Careers: A Narrative Analysis of Career Transition Themes and Outcomes Using Chaos Theory as a Guiding Metaphor

Science.gov (United States)

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…

The Evolving Demographic and Health Transition in Four Low- and Middle-Income Countries: Evidence from Four Sites in the INDEPTH Network of Longitudinal Health and Demographic Surveillance Systems.

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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.

Density-functional theory for fluid-solid and solid-solid phase transitions.

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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)=ε(σ/r)^{n}, where parameter n measures softness of the potential. We find that for 1/nfcc) structure while 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.

Maternal risk of breeding failure remained low throughout the demographic transitions in fertility and age at first reproduction in Finland.

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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.

Maternal Risk of Breeding Failure Remained Low throughout the Demographic Transitions in Fertility and Age at First Reproduction in Finland

Science.gov (United States)

Liu, Jianghua; Rotkirch, Anna; Lummaa, Virpi

2012-01-01

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. PMID:22529952

The historical fertility transition at the micro level: Southern Sweden 1815-1939

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Tommy Bengtsson

2014-02-01

Full Text Available Background: We know a great deal about the historical fertility transition at the macro level. The dominating focus on the macro level in previous research on the fertility transition means, however, that to a large extent we lack knowledge about details of the decline and empirical tests of the leading explanatory frameworks. Objective: Our aim is to explore socioeconomic fertility differentials in an industrializing community, to gain insight about the details and discuss possible mechanisms. The study starts well before industrialization and finishes at the end of the transition. Methods: We use longitudinal individual-level data from the Scanian Economic-Demographic Database, which contains demographic as well as socioeconomic information, including occupation, landholding, and income. In the analysis we use hazard regressions with shared frailty at the family level. Results: The transition involved not only parity-specific stopping but also spacing. While the upper social strata had higher fertility prior to the transition, they started to control their fertility earlier, by the 1880s, and also more consistently. Farmers, the middle class, and skilled workers followed in the decades after, and unskilled workers with some additional delay. Conclusions: These findings are partly inconsistent with several of the major explanations in the literature, such as mortality decline, increased female labor force participation, and a quantity-quality trade-off, but consistent with an innovation process where new ideas and attitudes about family limitation spread from the elite to other social groups. Comments: Further studies are required to empirically test the innovation-diffusion theory.

Ab initio theory of noble gas atoms in bcc transition metals.

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Jiang, Chao; Zhang, Yongfeng; Gao, Yipeng; Gan, Jian

2018-06-18

Systematic ab initio calculations based on density functional theory have been performed to gain fundamental understanding of the interactions between noble gas atoms (He, Ne, Ar and Kr) and bcc transition metals in groups 5B (V, Nb and Ta), 6B (Cr, Mo and W) and 8B (Fe). Our charge density analysis indicates that the strong polarization of nearest-neighbor metal atoms by noble gas interstitials is the electronic origin of their high formation energies. Such polarization becomes more significant with an increasing gas atom size and interstitial charge density in the host bcc metal, which explains the similar trend followed by the unrelaxed formation energies of noble gas interstitials. Upon allowing for local relaxation, nearby metal atoms move farther away from gas interstitials in order to decrease polarization, albeit at the expense of increasing the elastic strain energy. Such atomic relaxation is found to play an important role in governing both the energetics and site preference of noble gas atoms in bcc metals. Our most notable finding is that the fully relaxed formation energies of noble gas interstitials are strongly correlated with the elastic shear modulus of the bcc metal, and the physical origin of this unexpected correlation has been elucidated by our theoretical analysis based on the effective-medium theory. The kinetic behavior of noble gas atoms and their interaction with pre-existing vacancies in bcc transition metals have also been discussed in this work.

Exploring the transition of undergraduate medical students into a clinical clerkship using organizational socialization theory.

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Atherley, Anique E; Hambleton, Ian R; Unwin, Nigel; George, Colette; Lashley, Paula M; Taylor, Charles G

2016-04-01

Transitions in medical education are emotionally and socially dynamic; this may affect learning. Students transitioning from preclinical to clinical training may experience negative consequences. Less is understood about students' experiences during transitions within clinical training and influential factors. The authors used organizational socialization theory to explore a transition within the clinical years. Final-year medical students experienced a nine-week internal medicine clerkship; willing students participated. Students (n = 101; 97 %) completed a questionnaire with open-ended questions at the beginning and end of the clerkship and participated in six consecutive focus groups, until data saturation occurred (n = 37). Data were thematically analyzed. Socialization was challenging. Many students experienced difficulty developing relationships with team members. Students with a positive attitude experienced a smoother transition. Many students were uncertain of their roles, concerned about the workload and desired guidance to meet clerkship demands. This transition resulted in varied outcomes from enjoyment, increased confidence and student development through to disinterest. Transitions within clinical training are complex. Faculty should focus on adequate socialization in a new clerkship as this may facilitate a smoother transition. This may necessitate orientations, staff training, and formal student support. Further research is needed on the impact of these recommendations on learning and well-being.

How do demographic transitions and public health policies affect patients with Parkinson's disease in Brazil?

Science.gov (United States)

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.

Consumer-resource theory predicts dynamic transitions between outcomes of interspecific interactions

Science.gov (United States)

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.

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.

A study of isotropic-nematic transition of quadrupolar Gay-Berne fluid using density-functional theory approach

Science.gov (United States)

Singh, Ram Chandra; Ram, Jokhan

2011-11-01

The effects of quadrupole moments on the isotropic-nematic (IN) phase transitions are studied using the density-functional theory (DFT) for a Gay-Berne (GB) fluid for a range of length-to-breadth parameters ? in the reduced temperature range ? . The pair-correlation functions of the isotropic phase, which enter into the DFT as input parameters are found by solving the Percus-Yevick integral equation theory. The method used involves an expansion of angle-dependent functions appearing in the integral equations in terms of spherical harmonics and the harmonic coefficients are obtained by an iterative algorithm. All the terms of harmonic coefficients which involve l indices up to less than or equal to 6 are considered. The numerical accuracy of the results depends on the number of spherical harmonic coefficients considered for each orientation-dependent function. As the length-to-breadth ratio of quadrupolar GB molecules is increased, the IN transition is seen to move to lower density (and pressure) at a given temperature. It has been observed that the DFT is good to study the IN transitions in such fluids. The theoretical results have also been compared with the computer simulation results wherever they are available.

The Geography of Solar Photovoltaics (PV and a New Low Carbon Urban Transition Theory

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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.

Intelligent system to study demographic evolution

Science.gov (United States)

Rodrigues, M. de Fatima; Ramos, Carlos; Henriques, Pedro R.

1999-02-01

With three centuries of existence, the study of population's behavior implies the manipulation of large amounts of incomplete and imprecise data with high dimensionality. By virtue of its multidisciplinary character, the work in demography involves at least historicists, statisticians and computer scientists/programmers. Moreover, successful demographic analysis requires qualified experts, who have succeeded in analysing data through many views and relate different sources of information, including their personal knowledge of the epoch or regions under study. In this paper, we present an intelligent system to study demographic evolution (ISSDE). This system has a module based on on-line analytical processing (OLAP), which permits conducting multiple analysis, combining many data dimensions. It has a deductive database system, which allows the execution of elaborated queries through the database. It has another module for date treatment (generalization and/or reduction); and, at last, a data mining module to discover nontrivial relations hidden within data. We discover the data treatment procedure with two phases: data generalization and data reduction. In data generalization, utilizing knowledge about concept hierarchies and relevance of data, aggregation of attribute values is performed. In the data reduction phase, rough set theory is applied to compute the minimal attribute set. We highlight the advantages of combining attribute value generalization with rough set theory, to find a subset of attributes that lets the mining process discover more useful patterns, by providing results from the application of the C5.0 algorithm in a demographic relational database.

The age demographics of academic librarians a profession apart

CERN Document Server

Wilder, Stanley

2000-01-01

The Age Demographics of Academic Librarians: A Profession Apart discusses the current demographics of librarianship in North America and examines how a huge retiree rate will affect the profession. With the average age of librarians increasing dramatically since 1990, this book examines the changes that will have to take place in your library, such as recruiting, training, and working with a smaller staff. The Age Demographics of Academic Librarians provides you with insights on how to make your library's transition easier when several of your colleagues leave your library. Valuable and intelligent, The Age Demographics of Academic Librarians discusses trends through easy-to-read charts, tables, and comprehensive data analysis. Exploring possible reasons for the anomalies of this trend, this book explores several surprising facts, such as: 16 percent of the 1995 American Research Libraries population of librarians will retire by the year 2000, another 16 percent between 2000 and 2005, 24 percent between 2005 ...

Comparison of the order of magnetic phase transitions in several magnetocaloric materials using the rescaled universal curve, Banerjee and mean field theory criteria

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.

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...... and electrocatalysis, in which single crystal models are combined with Wulff construction-based ideas to produce descriptions of average nanocatalyst behavior. Then, I will proceed to describe explicitly DFT-based descriptions of catalysis on truly nanosized particles (

Complexity and demographic explanations of cumulative culture.

Science.gov (United States)

Querbes, Adrien; Vaesen, Krist; Houkes, Wybo

2014-01-01

Formal models have linked prehistoric and historical instances of technological change (e.g., the Upper Paleolithic transition, cultural loss in Holocene Tasmania, scientific progress since the late nineteenth century) to demographic change. According to these models, cumulation of technological complexity is inhibited by decreasing--while favoured by increasing--population levels. Here we show that these findings are contingent on how complexity is defined: demography plays a much more limited role in sustaining cumulative culture in case formal models deploy Herbert Simon's definition of complexity rather than the particular definitions of complexity hitherto assumed. Given that currently available empirical evidence doesn't afford discriminating proper from improper definitions of complexity, our robustness analyses put into question the force of recent demographic explanations of particular episodes of cultural change.

Invariant probabilities of transition functions

CERN Document Server

Zaharopol, Radu

2014-01-01

The structure of the set of all the invariant probabilities and the structure of various types of individual invariant probabilities of a transition function are two topics of significant interest in the theory of transition functions, and are studied in this book. The results obtained are useful in ergodic theory and the theory of dynamical systems, which, in turn, can be applied in various other areas (like number theory). They are illustrated using transition functions defined by flows, semiflows, and one-parameter convolution semigroups of probability measures. In this book, all results on transition probabilities that have been published by the author between 2004 and 2008 are extended to transition functions. The proofs of the results obtained are new. For transition functions that satisfy very general conditions the book describes an ergodic decomposition that provides relevant information on the structure of the corresponding set of invariant probabilities. Ergodic decomposition means a splitting of t...

LH transition theories and theory of H-mode

International Nuclear Information System (INIS)

Ward, D.J.

1996-01-01

Recent developments in H-mode theory are discussed with earlier work described to put new theories in context. Much of the recent work concerns the development of the radial electric field near the plasma edge and its impact on transport driven by fluctuations, and is the main topic discussed. (author)

Dynamic Phase Transitions In The Spin-2 Ising System Under An Oscillating Magnetic Field Within The Effective-Field Theory

International Nuclear Information System (INIS)

Ertas, Mehmet; Keskin, Mustafa; Deviren, Bayram

2010-01-01

The dynamic phase transitions are studied in the spin-2 Ising model under a time-dependent oscillating magnetic field by using the effective-field theory with correlations. The effective-field dynamic equation is derived by employing the Glauber transition rates and the phases in the system are obtained by solving this dynamic equation. The nature (first- or second-order) of the dynamic phase transition is characterized by investigating the thermal behavior of the dynamic order parameter and the dynamic phase transition temperatures are obtained. The dynamic phase diagrams are presented in (T/zJ, h/zJ) plane.

Optical to ultraviolet spectra of sandwiches of benzene and transition metal atoms: Time dependent density functional theory and many-body calculations

DEFF Research Database (Denmark)

Martinez, Jose Ignacio; García Lastra, Juan Maria; Lopez, M. J.

2010-01-01

The optical spectra of sandwich clusters formed by transition metal atoms (titanium, vanadium, and chromium) intercalated between parallel benzene molecules have been studied by time-dependent density functional theory (TDDFT) and many-body perturbation theory. Sandwiches with different number...

CPA theory of the magnetization in rare earth transition metal alloys

International Nuclear Information System (INIS)

Szpunar, B.; Lindgaard, P.A.

1976-11-01

Calculations were made of the magnetic moment per atom of the transition metal and the rare earth metal in the intermetallic compounds, Gdsub(1-x)Nisub(x), Gdsub(1-x)Fesub(x), Gdsub(1-x)Cosub(x), and Ysub(1-x)Cosub(x). A simple model of the disordered alloy consisting of spins localized on the rare earth atoms and interacting with a narrow d-band is considered. The magnetic moment of the alloy at zero temperature is calculated within the molecular field and Hartree-Fock approximations. Disorder is treated in the coherent potential approximation. Results are in good agreement with the experimental data obtained for the crystalline and amorphous intermetallic compounds. It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition metal pseudo spin. The interaction is mediated by an effective alloy medium calculated using the CPA theory and elliptic densities of states. (Auth.)

Current demographics suggest future energy supplies will be inadequate to slow human population growth.

Directory of Open Access Journals (Sweden)

John P DeLong

Full Text Available Influential demographic projections suggest that the global human population will stabilize at about 9-10 billion people by mid-century. These projections rest on two fundamental assumptions. The first is that the energy needed to fuel development and the associated decline in fertility will keep pace with energy demand far into the future. The second is that the demographic transition is irreversible such that once countries start down the path to lower fertility they cannot reverse to higher fertility. Both of these assumptions are problematic and may have an effect on population projections. Here we examine these assumptions explicitly. Specifically, given the theoretical and empirical relation between energy-use and population growth rates, we ask how the availability of energy is likely to affect population growth through 2050. Using a cross-country data set, we show that human population growth rates are negatively related to per-capita energy consumption, with zero growth occurring at ∼13 kW, suggesting that the global human population will stop growing only if individuals have access to this amount of power. Further, we find that current projected future energy supply rates are far below the supply needed to fuel a global demographic transition to zero growth, suggesting that the predicted leveling-off of the global population by mid-century is unlikely to occur, in the absence of a transition to an alternative energy source. Direct consideration of the energetic constraints underlying the demographic transition results in a qualitatively different population projection than produced when the energetic constraints are ignored. We suggest that energetic constraints be incorporated into future population projections.

Current demographics suggest future energy supplies will be inadequate to slow human population growth.

Science.gov (United States)

DeLong, John P; Burger, Oskar; Hamilton, Marcus J

2010-10-05

Influential demographic projections suggest that the global human population will stabilize at about 9-10 billion people by mid-century. These projections rest on two fundamental assumptions. The first is that the energy needed to fuel development and the associated decline in fertility will keep pace with energy demand far into the future. The second is that the demographic transition is irreversible such that once countries start down the path to lower fertility they cannot reverse to higher fertility. Both of these assumptions are problematic and may have an effect on population projections. Here we examine these assumptions explicitly. Specifically, given the theoretical and empirical relation between energy-use and population growth rates, we ask how the availability of energy is likely to affect population growth through 2050. Using a cross-country data set, we show that human population growth rates are negatively related to per-capita energy consumption, with zero growth occurring at ∼13 kW, suggesting that the global human population will stop growing only if individuals have access to this amount of power. Further, we find that current projected future energy supply rates are far below the supply needed to fuel a global demographic transition to zero growth, suggesting that the predicted leveling-off of the global population by mid-century is unlikely to occur, in the absence of a transition to an alternative energy source. Direct consideration of the energetic constraints underlying the demographic transition results in a qualitatively different population projection than produced when the energetic constraints are ignored. We suggest that energetic constraints be incorporated into future population projections.

Can quantum transition state theory be defined as an exact t = 0+ limit?

Science.gov (United States)

Jang, Seogjoo; Voth, Gregory A.

2016-02-01

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

Classical generalized transition-state theory. Application to a collinear reaction with two saddle points

International Nuclear Information System (INIS)

Garrett, B.C.; Truhlar, D.G.; Grev, R.S.

1981-01-01

Accurate classical dynamical fixed-energy reaction probabilities and fixed-temperature rate constants are calculated for the collinear reaction H + FH on a low-barrier model potential energy surface. The calculations cover energies from 0.1 to 100 kcal/mol above threshold and temperatures of 100 to 10,000 K. The accurate results are used to test five approximate theories: conventional transition-state theory (TST), canonical variational theory (CVT), improved canonical variational theory (ICVT), microcanonical variational theory (μVT), and the unified statistical model (US). The first four of these theories involve a single dividing surface in phase space, and the US theory involves three dividing surfaces. The tests are particularly interesting because the potential energy surface has two identical saddle points. At temperatures from 100 to 2000 K, the μVt is the most accurate theory, with errors in the range 11 to 14%; for temperatures from 2000 to 10,000 K, the US theory is the most successful, with errors in the range 3 to 14%. Over the whole range, a factor of 100 in temperature, both theories have errors of 35% or less. Even TST has errors of 47% or less over the whole factor-of-100 temperature range. Although the US model should become exact at threshold for this system, it already underestimates the reaction probability by a factor of 0.64 at 0.1 kcal/mol above threshold. TST and μVT agree with each other within 12% up to an energy 13 kcal/mol above the saddle point energy. 3 figures, 2 tables

[Demographic growth and the dynamics of specialization in the Third World].

Science.gov (United States)

Coussy, J

1983-01-01

All inquiries into the relationship between demographic growth and specialization in the 3rd World face a conflict found in the entire demographic-economic literature between 2 extreme positions that regard underdevelopment as caused either by the exploitation of developing by developed nations or as caused by overpopulation. This polarization of viewpoints appears to have deflected attention from more productive work and to have retarded empirical research. The object of the present study is to present a systematic and detailed critique of the opposing theoretical positions as a step in moving the debate into more productive areas. The section on the demographic explanation of the dynamics of specialization in developing countries considers its view of the comparative advantages and disadvantages created by demographic growth, including the impact of demographic growth on the availability of factors of production and on the structures of supply, demand, and exchange. The section discussing explanations of demographic-economic disequilibria in the 3rd World that are founded on the international division of labor describes the theory and its view of the division of labor in developing countries including such characteristics as the preponderance of the primary sector, the disproportionate attention to cash crops and relative neglect of subsistence crops, the importation of luxury goods, and the lack of local industrial production; the hypothesis that demographic growth and economic backwardness in developing countries both result from the international divisions of labor; the role of 3rd world demographic-economic disequilibrium in the continuation of the international division of labor; the possible advantages of demographic growth in stimulating supply, demand, and technological progress; and the increased probability of terminating the present international division of labor because of demographic pressure. The article ends with a general critique of the

A self consistent study of the phase transition in the scalar electroweak theory at finite temperature

International Nuclear Information System (INIS)

Kerres, U.; Mack, G.; Palma, G.

1994-12-01

We propose the study of the phase transition in the scalar electroweak theory at finite temperature by a two-step method. It combines i) dimensional reduction to a 3-dimensional lattice theory via perturbative blockspin transformation, and ii) either further real space renormalization group transformations, or solution of gap equations, for the 3d lattice theory. A gap equation can be obtained by using the Peierls inequality to find the best quadratic approximation to the 3d action. This method avoids the lack of self consistency of the usual treatments which do not separate infrared and UV-problems by introduction of a lattice cutoff. The effective 3d lattice action could also be used in computer simulations. (orig.)

A self consistent study of the phase transition in the scalar electroweak theory at finite temperature

International Nuclear Information System (INIS)

Kerres, U.

1995-01-01

We propose the study of the phase transition in the scalar electroweak theory at finite temperature by a two-step method. It combines i) dimensional reduction to a 3-dimensional lattice theory via perturbative blockspin transformation, and ii) either further real space renormalization group transformations, or solution of gap equations, for the 3d lattice theory. A gap equation can be obtained by using the Peierls inequality to find the best quadratic approximation to the 3d action. This method avoids the lack of self consistency of the usual treatments which do not separate infrared and UV-problems by introduction of a lattice cutoff. The effective 3d lattice action could also be used in computer simulations. ((orig.))

Employing Theories Far beyond Their Limits - Linear Dichroism Theory.

Science.gov (United States)

Mayerhöfer, Thomas G

2018-05-15

Using linear polarized light, it is possible in case of ordered structures, such as stretched polymers or single crystals, to determine the orientation of the transition moments of electronic and vibrational transitions. This not only helps to resolve overlapping bands, but also assigning the symmetry species of the transitions and to elucidate the structure. To perform spectral evaluation quantitatively, a sometimes "Linear Dichroism Theory" called approach is very often used. This approach links the relative orientation of the transition moment and polarization direction to the quantity absorbance. This linkage is highly questionable for several reasons. First of all, absorbance is a quantity that is by its definition not compatible with Maxwell's equations. Furthermore, absorbance seems not to be the quantity which is generally compatible with linear dichroism theory. In addition, linear dichroism theory disregards that it is not only the angle between transition moment and polarization direction, but also the angle between sample surface and transition moment, that influences band shape and intensity. Accordingly, the often invoked "magic angle" has never existed and the orientation distribution influences spectra to a much higher degree than if linear dichroism theory would hold strictly. A last point that is completely ignored by linear dichroism theory is the fact that partially oriented or randomly-oriented samples usually consist of ordered domains. It is their size relative to the wavelength of light that can also greatly influence a spectrum. All these findings can help to elucidate orientation to a much higher degree by optical methods than currently thought possible by the users of linear dichroism theory. Hence, it is the goal of this contribution to point out these shortcomings of linear dichroism theory to its users to stimulate efforts to overcome the long-lasting stagnation of this important field. © 2018 Wiley-VCH Verlag GmbH & Co. KGa

Density functional theory based screening of ternary alkali-transition metal borohydrides: A computational material design project

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...

Complexity and demographic explanations of cumulative culture.

Directory of Open Access Journals (Sweden)

Adrien Querbes

Full Text Available Formal models have linked prehistoric and historical instances of technological change (e.g., the Upper Paleolithic transition, cultural loss in Holocene Tasmania, scientific progress since the late nineteenth century to demographic change. According to these models, cumulation of technological complexity is inhibited by decreasing--while favoured by increasing--population levels. Here we show that these findings are contingent on how complexity is defined: demography plays a much more limited role in sustaining cumulative culture in case formal models deploy Herbert Simon's definition of complexity rather than the particular definitions of complexity hitherto assumed. Given that currently available empirical evidence doesn't afford discriminating proper from improper definitions of complexity, our robustness analyses put into question the force of recent demographic explanations of particular episodes of cultural change.

The impact of the demographic transition on dengue in Thailand: insights from a statistical analysis and mathematical modeling.

Directory of Open Access Journals (Sweden)

Derek A T Cummings

2009-09-01

that the critical vaccination fraction has not changed significantly, declining from an average of 85% to 80%. Clinical guidelines should consider the impact of continued increases in the age of dengue cases in Thailand. Countries in the region lagging behind Thailand in the demographic transition may experience the same increase as their population ages. The impact of demographic changes on the force of infection has been hypothesized for other diseases, but, to our knowledge, this is the first observation of this phenomenon. Please see later in the article for the Editors' Summary.

The demographic implications of nomadic herdsmen and farmers ...

African Journals Online (AJOL)

The paper examined the demographic implications resulting from nomadic herdsmen and farmers clashes in Nigeria. Relevant published texts across the country and the Malthusian theory provided the leverage for the study. It revealed that the Nigeria's population is dynamic and growing at a very rapid rate compared to ...

Dimensional reduction near the deconfinement transition

International Nuclear Information System (INIS)

Kurkela, A.

2009-01-01

It is expected that incorporating the center symmetry in the conventional dimensionally reduced effective theory for high-temperature SU(N) Yang-Mills theory, EQCD, will considerably extend its applicability towards the deconfinement transition. In this talk, I will discuss the construction of such center-symmetric effective theories and present results from their lattice simulations in the case of two colors. The simulations demonstrate that unlike EQCD, the new center symmetric theory undergoes a second order confining phase transition in complete analogy with the full theory. I will also describe the perturbative and non-perturbative matching of the parameters of the effective theory, and outline ways to further improve its description of the physics near the deconfinement transition. (author)

Theory of the pairbreaking superconductor-metal transition in nanowires

International Nuclear Information System (INIS)

Del Maestro, Adrian; Rosenow, Bernd; Sachdev, Subir

2009-01-01

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

Rural demographic change, rising wages and the restructuring of Chinese agriculture

DEFF Research Database (Denmark)

Li, Tianxiang; Yu, Wusheng; Baležentis, Tomas

2017-01-01

Purpose The purpose of this paper is to identify the effects of recent demographic transition and rising labor costs on agricultural production structure and pattern in China during 1998-2012. Design/methodology/approach The authors, first, theoretically discuss the effects of changing relative...

"Theory Becoming Alive": The Learning Transition Process of Newly Graduated Nurses in Canada.

Science.gov (United States)

Nour, Violet; Williams, Anne M

2018-01-01

Background Newly graduated nurses often encounter a gap between theory and practice in clinical settings. Although this has been the focus of considerable research, little is known about the learning transition process. Purpose The purpose of this study was to explore the experiences of newly graduated nurses in acute healthcare settings within Canada. This study was conducted to gain a greater understanding of the experiences and challenges faced by graduates. Methods Grounded theory method was utilized with a sample of 14 registered nurses who were employed in acute-care settings. Data were collected using in-depth interviews. Constant comparative analysis was used to analyze data. Results Findings revealed a core category, "Theory Becoming Alive," and four supporting categories: Entry into Practice, Immersion, Committing, and Evolving. Theory Becoming Alive described the process of new graduate nurses' clinical learning experiences as well as the challenges that they encountered in clinical settings after graduating. Conclusions This research provides a greater understanding of learning process of new graduate nurses in Canada. It highlights the importance of providing supportive environments to assist new graduate nurses to develop confidence as independent registered nurses in clinical areas. Future research directions as well as supportive educational strategies are described.

Uni-directional consumer-resource theory characterizing transitions of interaction outcomes

Science.gov (United States)

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

STATISTICAL EVALUATION OF THE IMPACT OF ECONOMIC FACTORS ON SOCIO-DEMOGRAPHICS OF THE COUNTRY

Directory of Open Access Journals (Sweden)

O. Evseenko

2014-04-01

Full Text Available In theory made a case the necessity of modeling economic and demographic indicators. The influences of economic, social and environmental indicators on social and demographic factors of development country are researeched. Given statistical evaluation of relationships based on correlation and regression analysis method.

[Recent demographic trends in Turkey].

Science.gov (United States)

Behar, C

1993-01-01

, contraceptive usage, and other indicators. Turkey thus appears to be divided into a region in which the demographic transition is well advanced and one where it is proceeding more slowly.

Baby Boomers and Beds: a Demographic Challenge for the Ages.

Science.gov (United States)

Song, Zirui; Ferris, Timothy G

2018-03-01

The United States is facing a significant demographic transition, with about 10,000 baby boomers turning age 65 each day. At the same time, the nation is experiencing a similarly striking transition in hospital capacity, as the supply of hospital beds has declined in recent decades. The juxtaposition of population aging and hospital capacity portends a potentially widening divergence between supply and demand for hospital care. We provide a closer look at current hospital capacity and a rethinking of the future role of hospital beds in meeting the needs of an aging population.

Are transition economy workers underpaid?

OpenAIRE

Adamchik, Vera A.; Brada, Josef C.; King, Arthur E.

2009-01-01

We examine the extent to which workers in transition and developed market economies are able to obtain wages that fully reflect their skills and labor force characteristics. We find that workers in two transition economies, the Czech Republic and Poland, are able to better attain the maximum wage available than are workers in a sample of developed market economies. This greater wage-setting efficiency in the transition economies ap-pears to be more the result of social and demographic charact...

Time-convolutionless mode-coupling theory near the glass transition: Numerical solutions for the Percus-Yevick model

International Nuclear Information System (INIS)

Kimura, Y.; Tokuyama, M.

2016-01-01

The full numerical solutions of the time-convolutionless modecoupling theory (TMCT) equation recently proposed by Tokuyama are compared with those of the ideal mode-coupling theory (MCT) equation based on the Percus- Yevick static structure factor for hard spheres qualitatively and quantitatively. The ergodic to non-ergodic transition at the critical volume fraction φ_c predicted by MCT is also shown to occur even for TMCT. Thus, φ_c of TMCT is shown to be much higher than that of MCT. The dynamics of coherent-intermediate scattering functions and their two-step relaxation process in a β stage are also discussed.

Filling- and interaction-driven Mott transition. Quantum cluster calculations within self-energy-functional theory

International Nuclear Information System (INIS)

Balzer, Matthias

2008-01-01

The central goal of this thesis is the examination of strongly correlated electron systems on the basis of the two-dimensional Hubbard model. We analyze how the properties of the Mott insulator change upon doping and with interaction strength. The numerical evaluation is done using quantum cluster approximations, which allow for a thermodynamically consistent description of the ground state properties. The framework of self-energy-functional theory offers great flexibility for the construction of cluster approximations. A detailed analysis sheds light on the quality and the convergence properties of different cluster approximations within the self-energy-functional theory. We use the one-dimensional Hubbard model for these examinations and compare our results with the exact solution. In two dimensions the ground state of the particle-hole symmetric model at half-filling is an antiferromagnetic insulator, independent of the interaction strength. The inclusion of short-range spatial correlations by our cluster approach leads to a considerable improvement of the antiferromagnetic order parameter as compared to dynamical mean-field theory. In the paramagnetic phase we furthermore observe a metal-insulator transition as a function of the interaction strength, which qualitatively differs from the pure mean-field scenario. Starting from the antiferromagnetic Mott insulator a filling-controlled metal-insulator transition in a paramagnetic metallic phase can be observed. Depending on the cluster approximation used an antiferromagnetic metallic phase may occur at first. In addition to long-range antiferromagnetic order, we also considered superconductivity in our calculations. The superconducting order parameter as a function of doping is in good agreement with other numerical methods, as well as with experimental results. (orig.)

Renormalization group approach to QCD phase transitions

International Nuclear Information System (INIS)

Midorikawa, S.; Yoshimoto, S.; So, H.

1987-01-01

Effective scalar theories for QCD are proposed to investigate the deconfining and chiral phase transitions. The orders of the phase transitions are determined by infrared stabilities of the fixed points. It is found that the transitions in SU(3) gauge theories are of 1st order for any number of massless flavors. The cases of SU(2) and SU(4) gauge theories are also discussed. (orig.)

High-pressure phase transitions - Examples of classical predictability

Science.gov (United States)

Celebonovic, Vladan

1992-09-01

The applicability of the Savic and Kasanin (1962-1967) classical theory of dense matter to laboratory experiments requiring estimates of high-pressure phase transitions was examined by determining phase transition pressures for a set of 19 chemical substances (including elements, hydrocarbons, metal oxides, and salts) for which experimental data were available. A comparison between experimental and transition points and those predicted by the Savic-Kasanin theory showed that the theory can be used for estimating values of transition pressures. The results also support conclusions obtained in previous astronomical applications of the Savic-Kasanin theory.

Individuation in Slovene emerging adults: its associations with demographics, transitional markers, achieved criteria for adulthood, and life satisfaction.

Science.gov (United States)

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.

[Epidemiological transition in Latin America: a comparison of four countries].

Science.gov (United States)

Albala, C; Vio, F; Yáñez, M

1997-06-01

In the last decade, Latin America has experienced important transformations in its health conditions, due to demographic changes and a rapid urbanization process. To analyze socioeconomic, demographic and epidemiological changes in Chile, Guatemala, Mexico and Uruguay and relate them to the different stages in the demographic and epidemiological transition of these countries. Data was obtained from official information of local and international organizations such as Pan-American Health Organization, United Nations, Latin American Center for Demography (CELADE) and World Bank. Guatemala is in a pre-transition stage with a high proportion of communicable diseases as causes of death (61%) as compared with Mexico (22%), Chile (13%) and Uruguay (7%). Mexico is in a prolonged transition situation and Chile is close to Uruguay in a post-transitional stage. Despite decreasing rates of mortality, the proportion of deaths represented by chronic diseases and injuries has increased to over 30% in all countries, except Uruguay. Adjusted mortality rates for cardiovascular diseases are lower in Latin American countries, as compared to Canada. However, excepting Guatemala, there are differences in the pattern of cardiovascular disease, with a higher mortality due to cerebrovascular and a lower mortality due to coronary artery diseases. An increment in non communicable diseases is expected for the next decades in Latin America. Analysis of demographic and epidemiological transition is crucial to define health policies and to adequate health systems to the new situations.

Socio-Demographic Determinants of Economic Growth: Age-Structure, Preindustrial Heritage and Sociolinguistic Integration

Science.gov (United States)

Crenshaw, Edward; Robison, Kristopher

2010-01-01

This study establishes a socio-demographic theory of international development derived from selected classical and contemporary sociological theories. Four hypotheses are tested: (1. population growth's effect on development depends on age-structure; (2. historic population density (used here as an indicator of preindustrial social complexity)…

Changes of marital behavior and family patterns in post-socialist countries: Delayed, incomplete or specific second demographic transition?

Directory of Open Access Journals (Sweden)

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

Towards the blackbox computation of magnetic exchange coupling parameters in polynuclear transition-metal complexes: theory, implementation, and application.

Science.gov (United States)

Phillips, Jordan J; Peralta, Juan E

2013-05-07

We present a method for calculating magnetic coupling parameters from a single spin-configuration via analytic derivatives of the electronic energy with respect to the local spin direction. This method does not introduce new approximations beyond those found in the Heisenberg-Dirac Hamiltonian and a standard Kohn-Sham Density Functional Theory calculation, and in the limit of an ideal Heisenberg system it reproduces the coupling as determined from spin-projected energy-differences. Our method employs a generalized perturbative approach to constrained density functional theory, where exact expressions for the energy to second order in the constraints are obtained by analytic derivatives from coupled-perturbed theory. When the relative angle between magnetization vectors of metal atoms enters as a constraint, this allows us to calculate all the magnetic exchange couplings of a system from derivatives with respect to local spin directions from the high-spin configuration. Because of the favorable computational scaling of our method with respect to the number of spin-centers, as compared to the broken-symmetry energy-differences approach, this opens the possibility for the blackbox exploration of magnetic properties in large polynuclear transition-metal complexes. In this work we outline the motivation, theory, and implementation of this method, and present results for several model systems and transition-metal complexes with a variety of density functional approximations and Hartree-Fock.

Critical behavior at the deconfinement phase phase transition of SU(2) lattice gauge theory in (2+1) dimensions

International Nuclear Information System (INIS)

Christensen, J.; Damgaard, P.H.

1991-01-01

The finite-temperature deconfinement phase transition of SU(2) lattice gauge theory in (2+1) dimensions is studied by Monte Carlo methods. Comparison is made with the expected form of correlation functions on both sides of the critical point. The critical behavior is compared with expectations based on universality arguments. Attempts are made to extract unbiased values of critical exponents on several lattices sizes. The behavior of Polyakov loops in higher representations of the gauge group is studied close to the phase transition. (orig.)

Non-equilibrium random matrix theory. Transition probabilities

International Nuclear Information System (INIS)

Pedro, Francisco Gil; Westphal, Alexander

2016-06-01

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.

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.

Hypocritical transitions? The challenge of urban sustainable mobility transition

DEFF Research Database (Denmark)

Vogel, Nina

of a sustainable mobility discourse can be traced in the policy documents, how mobility is framed, and which arguments are used to legitimate or envision strategies and planning practices. Is Fredericia performing a transition towards low-carbon mobility? The paper will draw on concepts from transition theory...... urban complexity within transition processes. Transitions are always taking place, but the question is which direction they take and if these directions are in line with a planning approach for sustainable mobility....

ω→π0γ* and ϕ→π0γ* transition form factors in dispersion theory

Science.gov (United States)

Schneider, Sebastian P.; Kubis, Bastian; Niecknig, Franz

2012-09-01

We calculate the ω→π0γ* and ϕ→π0γ* 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 ω→π0μ+μ- decay spectrum by the NA60 collaboration, and strongly encourage experimental investigation of the Okubo-Zweig-Iizuka forbidden ϕ→π0ℓ+ℓ- decays in order to understand the strong deviations from vector-meson dominance found in these transition form factors.

Demographic, social, and economic effects on Mexican causes of death in 1990.

Science.gov (United States)

Pick, J B; Butler, E W

1998-01-01

This study examined spatial geographic patterns of cause of death and 28 demographic and socioeconomic influences on causes of death for 31 Mexican states plus the Federal District for 1990. Mortality data were obtained from the state death registration system and are age standardized. The 28 socioeconomic variables were obtained from Census records. Analysis included 2 submodels: one with all 28 socioeconomic variables in a stepwise regression, and one with each of the 4 groups of factors. The conceptual model is based on epidemiological transition theory and empirical findings. There are 4 stages in mortality decline. Effects are grouped as demographic, sociocultural, economic prosperity, and housing, health, and crime factors. Findings indicate that cancer and cardiovascular disease were strongly correlated and consistently high in border areas as well as the Federal District and Jalisco. Respiratory mortality had higher values in the Federal District, Puebla, and surrounding states, as well as Jalisco. The standardized total mortality rate was only in simple correlations associated inversely with underemployment. All cause specific mortality was associated with individual factors. Respiratory mortality was linked with manufacturing work force. Cardiovascular and cancer mortality were associated with socioeconomic factors. In submodel I, cause specific mortality was predicted by crowding, housing characteristics, marriage and divorce, and manufacturing work force. In submodel II, economic group factors had the strongest model fits explaining 33-60% of the "r" square. Hypothesized effects were only partially validated.

Localization transition in SU(3) gauge theory

Science.gov (United States)

Kovács, Tamás G.; Vig, Réka Á.

2018-01-01

We study the Anderson-like localization transition in the spectrum of the Dirac operator of quenched QCD. Above the deconfining transition we determine the temperature dependence of the mobility edge separating localized and delocalized eigenmodes in the spectrum. We show that the temperature where the mobility edge vanishes and localized modes disappear from the spectrum coincides with the critical temperature of the deconfining transition. We also identify topological charge related close to zero modes in the Dirac spectrum and show that they account for only a small fraction of localized modes, a fraction that is rapidly falling as the temperature increases.

Disentangling phase transitions and critical points in the proton–neutron interacting boson model by catastrophe theory

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.

Problems in particle theory

International Nuclear Information System (INIS)

Adler, S.L.; Wilczek, F.

1993-11-01

Areas of emphasis include acceleration algorithms for the Monte Carlo analysis of lattice field and gauge theories, quaternionic generalizations of complex quantum mechanics and field theory, application of the renormalization group to the QCD phase transition, the quantum Hall effect, and black holes. Other work involved string theory, statistical properties of energy levels in integrable quantum systems, baryon asymmetry and the electroweak phase transition, anisotropies of the cosmic microwave background, and theory of superconductors

Theory of the transition temperature of superconducting amorphous transition metals

International Nuclear Information System (INIS)

Zwicknagel, G.

1979-11-01

In the present paper first the transition temperature Tsub(c) is shown to be a local quantity, which depends on the (average) short range order, and second it is demonstrated how to calculate local electronic properties in the framework of a short range order model and the transition temperature of amorphous systems based on accepted structure models of the amorphous state. In chapter I the theoretical basis of this work is presented in brief. The model used to study the role of short range order (in periodically ordered as well as in disordered system) is described in chapter II. The results of this model for the periodically ordered case are compared in chapter III with band structure calculations. In chapter IV it is shown how to establish short range order models for disordered systems and what kind of information can be obtained with respect to the electronic properties. Finally in chapter V it is discussed to what extend the interpretation of the transition temperature Tsub(c) as being determined by short range order effects can be supported by the electronic properties, which are calculated in the chapters III and IV. (orig.) [de

Barrierless association of CF2 and dissociation of C2F4 by variational transition-state theory and system-specific quantum Rice–Ramsperger–Kassel theory

Science.gov (United States)

Bao, Junwei Lucas; Zhang, Xin

2016-01-01

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. PMID:27834727

Can decoherence make quantum theories unfalsifiable? Understanding the quantum-to-classical transition without it

International Nuclear Information System (INIS)

Oriols, X.

2016-01-01

Exact predictions for most quantum systems are computationally inaccessible. This is the so-called many body problem, which is present in most common interpretations of quantum mechanics. Therefore, predictions of natural quantum phenomena have to rely on some approximations (assumptions or simplifications). In the literature, there are different types of approximations, ranging from those whose justification is basically based on theoretical developments to those whose justification lies on the agreement with experiments. This last type of approximations can convert a quantum theory into an “unfalsifiable” quantum theory, true by construction. On the practical side, converting some part of a quantum theory into an “unfalsifiable” one ensures a successful modeling (i.e. compatible with experiments) for quantum engineering applications. An example of including irreversibility and dissipation in the Bohmian modeling of open systems is presented. On the ontological level, however, the present-day foundational problems related to controversial quantum phenomena have to avoid (if possible) being contaminated by the unfalsifiability originated from the many body problem. An original attempt to show how the Bohmian theory itself (minimizing the role of many body approximations) explains the transitions from a microscopic quantum system towards a macroscopic classical one is presented. (paper)

Phase transitions modern applications

CERN Document Server

Gitterman, Moshe

2014-01-01

This book provides a comprehensive review of the theory of phase transitions and its modern applications, based on the five pillars of the modern theory of phase transitions i.e. the Ising model, mean field, scaling, renormalization group and universality. This expanded second edition includes, along with a description of vortices and high temperature superconductivity, a discussion of phase transitions in chemical reaction and moving systems. The book covers a close connection between phase transitions and small world phenomena as well as scale-free systems such as the stock market and the Internet. Readership: Scientists working in different fields of physics, chemistry, biology and economics as well as teaching material for undergraduate and graduate courses.

Finite-temperature second-order many-body perturbation and Hartree–Fock theories for one-dimensional solids: An application to Peierls and charge-density-wave transitions in conjugated polymers

International Nuclear Information System (INIS)

He, Xiao; Ryu, Shinsei; Hirata, So

2014-01-01

Finite-temperature extensions of ab initio Gaussian-basis-set spin-restricted Hartree–Fock (HF) and second-order many-body perturbation (MP2) theories are implemented for infinitely extended, periodic, one-dimensional solids and applied to the Peierls and charge-density-wave (CDW) transitions in polyyne and all-trans polyacetylene. The HF theory predicts insulating CDW ground states for both systems in their equidistant structures at low temperatures. In the same structures, they turn metallic at high temperatures. Starting from the “dimerized” low-temperature equilibrium structures, the systems need even higher temperatures to undergo a Peierls transition, which is accompanied by geometric as well as electronic distortions from dimerized to non-dimerized forms. The conventional finite-temperature MP2 theory shows a sign of divergence in any phase at any nonzero temperature and is useless. The renormalized finite-temperature MP2 (MP2R) theory is divergent only near metallic electronic structures, but is well behaved elsewhere. MP2R also predicts CDW and Peierls transitions occurring at two different temperatures. The effect of electron correlation is primarily to lower the Peierls transition temperature

The protection motivation theory within the stages of the transtheoretical model - stage-specific interplay of variables and prediction of exercise stage transitions.

Science.gov (United States)

Lippke, Sonia; Plotnikoff, Ronald C

2009-05-01

Two different theories of health behaviour have been chosen with the aim of theory integration: a continuous theory (protection motivation theory, PMT) and a stage model (transtheoretical model, TTM). This is the first study to test whether the stages of the TTM moderate the interrelation of PMT-variables and the mediation of motivation, as well as PMT-variables' interactions in predicting stage transitions. Hypotheses were tested regarding (1) mean patterns, stage pair-comparisons and nonlinear trends using ANOVAs; (2) prediction-patterns for the different stage groups employing multi-group structural equation modelling (MSEM) and nested model analyses; and (3) stage transitions using binary logistic regression analyses. Adults (N=1,602) were assessed over a 6 month period on their physical activity stages, PMT-variables and subsequent behaviour. (1) Particular mean differences and nonlinear trends in all test variables were found. (2) The PMT adequately fitted the five stage groups. The MSEM revealed that covariances within threat appraisal and coping appraisal were invariant and all other constrains were stage-specific, i.e. stage was a moderator. Except for self-efficacy, motivation fully mediated the relationship between the social-cognitive variables and behaviour. (3) Predicting stage transitions with the PMT-variables underscored the importance of self-efficacy. Only when threat appraisal and coping appraisal were high, stage movement was more likely in the preparation stage. Results emphasize stage-specific differences of the PMT mechanisms, and hence, support the stage construct. The findings may guide further theory building and research integrating different theoretical approaches.

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

-spin. The interaction is mediated by an effective alloy medium calculated using the CPA theory and elliptic densities of states. Es wird gezeigt, daß die Temperaturabhängigkeit der magnetischen Momente und die Curie-Temperatur sowie die Temperatur der ferrimagnetischen Kompensation für Gd1-xTx (T = Co, Ni und Fe) und Y......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......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...

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...... the image-finiteness restriction, a fact that makes this development general and robust....

Center-symmetric effective theory for high-temperature SU(2) Yang-Mills theory

International Nuclear Information System (INIS)

Forcrand, Ph. de; Kurkela, A.; Vuorinen, A.

2008-01-01

We construct and study a dimensionally reduced effective theory for high-temperature SU(2) Yang-Mills theory that respects all the symmetries of the underlying theory. Our main motivation is to study whether the correct treatment of the center symmetry can help extend the applicability of the dimensional reduction procedure towards the confinement transition. After performing perturbative matching to the full theory at asymptotically high temperatures, we map the phase diagram of the effective theory using nonperturbative lattice simulations. We find that at lower temperature the theory undergoes a second-order confining phase transition, in complete analogy with the full theory, which is a direct consequence of having incorporated the center symmetry

Asia's demographic miracle: 50 years of unprecedented change.

Science.gov (United States)

Leete, R; Alam, I

1999-12-01

The demographic landscape of Asia has seen unprecedented changes over the past 50 years. The transition from high to low mortality and fertility rates has made the eventual stabilization of the world's population a real possibility. The demographic success of Asia is associated with the stunning economic and social changes that have taken place during this period. Aside from social and economic improvements, population and health policies also played a major part in shaping the region's demographic transformation. National programs made a substantial contribution to increasing contraceptive use, lowering fertility, and slowing population growth. The success of family planning programs was frequently supported by positive changes in the demand for children. As the initial impact of the recent financial and economic crisis has shown, the Asian demographic miracle cannot be taken for granted. Since mid-1997, the crisis has interrupted and reversed the region's remarkable development gains. Economic downturns often tend to affect the social sectors unevenly. Strengthening the provision of basic social services, including reproductive health and care of the elderly, particularly in poor nations, will remain a challenge in the next century. The establishment of goals, including in areas such as HIV/AIDS, will help Asian countries realize the vision of the International Conference on Population and Development¿s 20-year Programme of Action.

Experimental and theoretical examples of the value and limitations of transition state theory

International Nuclear Information System (INIS)

Golden, D.M.

1979-01-01

Value and limitations of transition-state theory (TST) are reviewed. TST analyses of the temperature dependence of the ''direct'' reactions CH 3 + CH 3 CHO → CH 4 + CH 3 CO (1) and O + CH 4 → OH + CH 3 (2) are presented in detail, and other examples of TST usefulness are recalled. Limitations are discussed for bimolecular processes in terms of ''complex'' vs ''direct'' mechanisms. The reaction OH + CO → CO 2 + H is discussed in this context. Limitations for unimolecular processes seem to arise only for simple bond fission processes, and recent advances are noted. 2 figures, 5 tables

Experimental and theoretical examples of the value and limitations of transition state theory

Science.gov (United States)

Golden, D. M.

1979-01-01

Value and limitations of transition-state theory (TST) are reviewed. TST analyses of the temperature dependence of the 'direct' reactions CH3 + CH3CHO yields CH4 + CH3CO(1) and O + CH4 yields OH + CH3(2) are presented in detail, and other examples of TST usefulness are recalled. Limitations are discussed for bimolecular processes in terms of 'complex' vs. 'direct' mechanisms. The reaction OH + CO yields CO2 + H is discussed in this context. Limitations for unimolecular processes seem to arise only for simple bond fission processes, and recent advances are noted.

Determinants of fertility in Rwanda in the context of a fertility transition: a secondary analysis of the 2010 Demographic and Health Survey.

Science.gov (United States)

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 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 and services at schools and via health campaigns, and involvement of men in family planning decision making.

Child survival and the demographic "trap".

Science.gov (United States)

Kalish, S

1992-02-01

A debate within the UK public health community has centered around the feasibility of campaigns to improve child survival rates in Africa in the absence of equally aggressive efforts to increase family planning acceptance. The central spokesperson in this debate, Maurice King of the University of Leeds, has argued that population growth in sub-Saharan countries is undermining the carrying capacity of available resources and threatening ecological collapse. These countries are not exhibiting the characteristic demographic transition pattern, in which declining death rates eventually create conditions conducive to lower birth rates. Instead, they have fallen into a "demographic trap " in which population increases are outstripping growth in food production. To remedy this situation, King advocates the introduction of the concept of sustainability of the ecological foundations of health into the World Health Organizations's official definition of health. Richard Jolly of UNICEF has countered King's articles with the insistence that UNICEF has long supported child survival within the broader context of family planning provision and advocacy of birth spacing.

Phase transitions in finite systems

Energy Technology Data Exchange (ETDEWEB)

Chomaz, Ph. [Grand Accelerateur National d' Ions Lourds (GANIL), DSM-CEA / IN2P3-CNRS, 14 - Caen (France); Gulminelli, F. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire

2002-07-01

In this series of lectures we will first review the general theory of phase transition in the framework of information theory and briefly address some of the well known mean field solutions of three dimensional problems. The theory of phase transitions in finite systems will then be discussed, with a special emphasis to the conceptual problems linked to a thermodynamical description for small, short-lived, open systems as metal clusters and data samples coming from nuclear collisions. The concept of negative heat capacity developed in the early seventies in the context of self-gravitating systems will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. Finally a careful study of the thermodynamical limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. (authors)

Phase transitions in finite systems

International Nuclear Information System (INIS)

Chomaz, Ph.; Gulminelli, F.

2002-01-01

In this series of lectures we will first review the general theory of phase transition in the framework of information theory and briefly address some of the well known mean field solutions of three dimensional problems. The theory of phase transitions in finite systems will then be discussed, with a special emphasis to the conceptual problems linked to a thermodynamical description for small, short-lived, open systems as metal clusters and data samples coming from nuclear collisions. The concept of negative heat capacity developed in the early seventies in the context of self-gravitating systems will be reinterpreted in the general framework of convexity anomalies of thermo-statistical potentials. The connection with the distribution of the order parameter will lead us to a definition of first order phase transitions in finite systems based on topology anomalies of the event distribution in the space of observations. Finally a careful study of the thermodynamical limit will provide a bridge with the standard theory of phase transitions and show that in a wide class of physical situations the different statistical ensembles are irreducibly inequivalent. (authors)

A demographic-economic explanation of political stability: Mauritius as a microcosm.

Science.gov (United States)

Lempert, D

1987-06-01

"This paper examines current models of economic and political development--social modernization theory, political and economic characteristics of stable regimes, and cross country analysis of political stability--and tests them on the Indian Ocean Island of Mauritius. The analysis continues with a causal explanation for political stability in Mauritius' recent history, derived from an examination of economic policies and demographic patterns. Political change in Mauritius over the past sixty years seems to be explained best by a model for political stability which integrates specific economic and demographic factors. The model, applicable to development in other third world nations, revises Malthus' conclusion that population and economic conditions move in an oscillatory relationship and replaces it with a more comprehensive theory, suggesting that political stability is a function of both economic development and a repeating cyclical relationship between economics and population." excerpt

Falling off the ladder: Using focal theory to understand and improve the educational experiences of young people in transition from public care.

Science.gov (United States)

Hollingworth, Katie; Jackson, Sonia

2016-10-01

Coleman's focal theory, developed in relation to adolescents in the general population, appears to offer some explanation for the poor educational achievement and social exclusion of care leavers, but has been little tested empirically. This paper revisits data from two studies of care-experienced young people aged 18-25, drawing on qualitative interviews in the UK and four other European countries, to see if focal theory would have helped to predict their educational progression or otherwise. The lives of research participants were found to be characterised by disruptions and uncertainty, with multiple challenges confronting them in quick succession, making it hard for them to pace their transitions as, according to focal theory, other young people do. Findings suggest that the theory could be used to inform policy designed to improve educational outcomes and should be incorporated into training for those responsible for supporting care leavers through their transition to adulthood. Copyright © 2016 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Exact theory of dense amorphous hard spheres in high dimension. II. The high density regime and the Gardner transition.

Science.gov (United States)

Kurchan, Jorge; Parisi, Giorgio; Urbani, Pierfrancesco; Zamponi, Francesco

2013-10-24

We consider the theory of the glass phase and jamming of hard spheres in the large space dimension limit. Building upon the exact expression for the free-energy functional obtained previously, we find that the random first order transition (RFOT) scenario is realized here with two thermodynamic transitions: the usual Kauzmann point associated with entropy crisis and a further transition at higher pressures in which a glassy structure of microstates is developed within each amorphous state. This kind of glass-glass transition into a phase dominating the higher densities was described years ago by Elisabeth Gardner, and may well be a generic feature of RFOT. Microstates that are small excitations of an amorphous matrix-separated by low entropic or energetic barriers-thus emerge naturally, and modify the high pressure (or low temperature) limit of the thermodynamic functions.

An investigation of one- versus two-dimensional semiclassical transition state theory for H atom abstraction and exchange reactions.

Science.gov (United States)

Greene, Samuel M; Shan, Xiao; Clary, David C

2016-02-28

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.

Phase transitions in field theory

International Nuclear Information System (INIS)

Carvalho, C.A.A. de; Bollini, C.G.; Giambiagi, J.J.

1984-01-01

By means of an example for which the effective potential is explicitly calculable (up to the one loop approximation), it is discussed how a phase transition takes place as the temperature is increased and pass from spontaneously broken symmetry to a phase in which the symmetry is restored. (Author) [pt

Using demographic data to better interpret pitfall trap catches.

Science.gov (United States)

Matalin, Andrey V; Makarov, Kirill V

2011-01-01

The results of pitfall trapping are often interpreted as abundance in a particular habitat. At the same time, there are numerous cases of almost unrealistically high catches of ground beetles in seemingly unsuitable sites. The correlation of catches by pitfall trapping with the true distribution and abundance of Carabidae needs corroboration. During a full year survey in 2006/07 in the Lake Elton region (Volgograd Area, Russia), 175 species of ground beetles were trapped. Considering the differences in demographic structure of the local populations, and not their abundances, three groups of species were recognized: residents, migrants and sporadic. In residents, the demographic structure of local populations is complete, and their habitats can be considered "residential". In migrants and sporadic species, the demographic structure of the local populations is incomplete, and their habitats can be considered "transit". Residents interact both with their prey and with each other in a particular habitat. Sporadic species are hardly important to a carabid community because of their low abundances. The contribution of migrants to the structure of carabid communities is not apparent and requires additional research. Migrants and sporadic species represent a "labile" component in ground beetles communities, as opposed to a "stable" component, represented by residents. The variability of the labile component substantially limits our interpretation of species diversity in carabid communities. Thus, the criteria for determining the most abundant, or dominant species inevitably vary because the abundance of migrants in some cases can be one order of magnitude higher than that of residents. The results of pitfall trapping adequately reflect the state of carabid communities only in zonal habitats, while azonal and disturbed habitats are merely transit ones for many species of ground beetles. A study of the demographic structure of local populations and assessment of the

High pressure phase transitions in Mg{sub 1-x}Ca{sub x}O: Theory

Energy Technology Data Exchange (ETDEWEB)

Srivastava, Anurag; Chauhan, Mamta [Advanced Material Research Lab, Indian Institute of Information Technology and Management, Gwalior (India); Singh, R.K. [Department of Physics, ITM University, Gurgaon (India); Padegaonker, Rishikesh [Indian Embassy School, Sana (Yemen)

2011-08-15

We have analysed a B1 {yields} B2 structural phase transitions in Mg{sub 1-x}Ca{sub x}O solid solutions and their ground state properties by using first principle density functional theory and charge transfer interaction potential (CTIP) approach. The effects of exchange-correlation interactions are handled by the generalized gradient approximation with Perdew-Burke-Ernzerhof type parameterization. CTIP approach includes the long range modified Coulomb with charge transfer interactions and short range part of this model includes the van der Waals as well as Hafemeister Flygare type overlap repulsive interactions. The study observes a linear variation of calculated transition pressure, bulk modulus and lattice parameter of Mg{sub 1-x}Ca{sub x}O as a function of Ca composition. The observed results for the end point members are in agreement to their experimental counterparts and the deviations have been discussed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Understanding Students' Transition to High School: Demographic Variation and the Role of Supportive Relationships.

Science.gov (United States)

Benner, Aprile D; Boyle, Alaina E; Bakhtiari, Farin

2017-10-01

The transition to high school is disruptive for many adolescents, yet little is known about the supportive relational processes that might attenuate the challenges students face as they move from middle to high school, particularly for students from more diverse backgrounds. Identifying potential buffers that protect youth across this critical educational transition is important for informing more effective support services for youth. In this study, we investigated how personal characteristics (gender, nativity, parent education level) and changes in support from family, friends, and school influenced changes in socioemotional adjustment and academic outcomes across the transition from middle to high school. The data were drawn from 252 students (50% females, 85% Latina/o). The results revealed declines in students' grades and increases in depressive symptoms and feelings of loneliness across the high school transition, with key variation by student nativity and gender. Additionally, stable/increasing friend support and school belonging were both linked to less socioemotional disruptions as students moved from middle to high school. Increasing/stable school belonging was also linked to increases in school engagement across the high school transition. These findings suggest that when high school transitions disrupt supportive relationships with important others in adolescents' lives, adolescents' socioemotional well-being and, to a lesser extent, their academic engagement are also compromised. Thus, in designing transition support activities, particularly for schools serving more low-income and race/ethnic minority youth, such efforts should strive to acclimate new high school students by providing inclusive, caring environments and positive connections with educators and peers.

On the interplay between string theory and field theory

International Nuclear Information System (INIS)

Brunner, I.

1998-01-01

In this thesis, we have discussed various aspects of branes in string theory and M-theory. In chapter 2 we were able to construct six-dimensional chiral interacting eld theories from Hanany-Witten like brane setups. The field theory requirement that the anomalies cancel was reproduced by RR-charge conservation in the brane setup. The data of the Hanany-Witten setup, which consists of brane positions, was mapped to instanton data. The orbifold construction can be extended to D and E type singularities. In chapter 3 we discussed a matrix conjecture, which claims that M-theory in the light cone gauge is described by the quantum mechanics of D0 branes. Toroidal compactifications of M-theory have a description in terms of super Yang-Mills theory an the dual torus. For more than three compactified dimensions, more degrees of freedom have to be added. In some sense, the philosophy in this chapter is orthogonal to the previous chapter: Here, we want to get M-theory results from eld theory considerations, whereas in the previous chapter we obtained eld theory results by embedding the theories in string theory. Our main focus was on the compactification on T 6 , which leads to complications. Here, the Matrix model is again given by an eleven dimensional theory, not by a lower dimensional field theory. Other problems and possible resolutions of Matrix theory are discussed at the end of chapter 3. In the last chapter we considered M- and F-theory compactifications on Calabi-Yau fourfolds. After explaining some basics of fourfolds, we showed that the web of fourfolds is connected by singular transitions. The two manifolds which are connected by the transition are different resolutions of the same singular manifold. The resolution of the singularities can lead to a certain type of divisors, which lead to non-perturbative superpotentials, when branes wrap them. The vacua connected by the transitions can be physically very different. (orig.)

On the interplay between string theory and field theory

Energy Technology Data Exchange (ETDEWEB)

Brunner, I.

1998-07-08

In this thesis, we have discussed various aspects of branes in string theory and M-theory. In chapter 2 we were able to construct six-dimensional chiral interacting eld theories from Hanany-Witten like brane setups. The field theory requirement that the anomalies cancel was reproduced by RR-charge conservation in the brane setup. The data of the Hanany-Witten setup, which consists of brane positions, was mapped to instanton data. The orbifold construction can be extended to D and E type singularities. In chapter 3 we discussed a matrix conjecture, which claims that M-theory in the light cone gauge is described by the quantum mechanics of D0 branes. Toroidal compactifications of M-theory have a description in terms of super Yang-Mills theory an the dual torus. For more than three compactified dimensions, more degrees of freedom have to be added. In some sense, the philosophy in this chapter is orthogonal to the previous chapter: Here, we want to get M-theory results from eld theory considerations, whereas in the previous chapter we obtained eld theory results by embedding the theories in string theory. Our main focus was on the compactification on T{sup 6}, which leads to complications. Here, the Matrix model is again given by an eleven dimensional theory, not by a lower dimensional field theory. Other problems and possible resolutions of Matrix theory are discussed at the end of chapter 3. In the last chapter we considered M- and F-theory compactifications on Calabi-Yau fourfolds. After explaining some basics of fourfolds, we showed that the web of fourfolds is connected by singular transitions. The two manifolds which are connected by the transition are different resolutions of the same singular manifold. The resolution of the singularities can lead to a certain type of divisors, which lead to non-perturbative superpotentials, when branes wrap them. The vacua connected by the transitions can be physically very different. (orig.)

Demographics as predictors of suicidal thoughts and behaviors: A meta-analysis.

Directory of Open Access Journals (Sweden)

Xieyining Huang

Full Text Available Certain demographic factors have long been cited to confer risk or protection for suicidal thoughts and behaviors. However, many studies have found weak or non-significant effects. Determining the effect strength and clinical utility of demographics as predictors is crucial for suicide risk assessment and theory development. As such, we conducted a meta-analysis to determine the effect strength and clinical utility of demographics as predictors.We searched PsycInfo, PubMed, and GoogleScholar for studies published before January 1st, 2015. Inclusion criteria required that studies use at least one demographic factor to longitudinally predict suicide ideation, attempt, or death. The initial search yielded 2,541 studies, 159 of which were eligible. A total of 752 unique statistical tests were included in analysis.Suicide death was the most commonly studied outcome, followed by attempt and ideation. The average follow-up length was 9.4 years. The overall effects of demographic factors studied in the field as risk factors were significant but weak, and that of demographic factors studied as protective factors were non-significant. Adjusting for publication bias further reduced effect estimates. No specific demographic factors appeared to be strong predictors. The effects were consistent across multiple moderators.At least within the narrow methodological constraints of the existing literature, demographic factors were statistically significant risk factors, but not protective factors. Even as risk factors, demographics offer very little improvement in predictive accuracy. Future studies that go beyond the limitations of the existing literature are needed to further understand the effects of demographics.

Electronic phase transitions

CERN Document Server

Kopaev, YuV

1992-01-01

Electronic Phase Transitions deals with topics, which are presently at the forefront of scientific research in modern solid-state theory. Anderson localization, which has fundamental implications in many areas of solid-state physics as well as spin glasses, with its influence on quite different research activities such as neural networks, are two examples that are reviewed in this book. The ab initio statistical mechanics of structural phase transitions is another prime example, where the interplay and connection of two unrelated disciplines of solid-state theory - first principle ele

Changes in Attitude towards Gender Inequality in the

OpenAIRE

Vakil Ahmadi

2013-01-01

Introduction Gender inequality stems from social factors in each society. In theories of gender inequality, it has been assumed that family role in reproduction of gender inequality is of crucial importance (Bourdieu 2001, Chaftez 1999, dyson 2001). Demographic transition is one of the factors in the structure of family changes in recent century. Demographic transition is applied to changes from high levels of mortality and fertility to low levels (Lucas & meyer 2002). Demographic transit...

Comments on the electroweak phase transition

International Nuclear Information System (INIS)

Dine, M.; Leigh, R.G.; Huet, P.; Linde, A.; Linde, D.

1992-01-01

We report on an investigation of various problems related to the theory of the electroweak phase transition. This includes a determination of the nature of the phase transition, a discussion of the possible role of higher order radiative corrections and the theory of the formation and evolution of the bubbles of the new phase. We find in particular that no dangerous linear terms appear in the effective potential. However, the strength of the first-order phase transition is 2/3 times less than what follows from the one-loop approximation. This rules out baryogenesis in the minimal version of the electroweak theory with light Higgs bosons. (orig.)

Wetting transitions: First order or second order

International Nuclear Information System (INIS)

Teletzke, G.F.; Scriven, L.E.; Davis, H.T.

1982-01-01

A generalization of Sullivan's recently proposed theory of the equilibrium contact angle, the angle at which a fluid interface meets a solid surface, is investigated. The generalized theory admits either a first-order or second-order transition from a nonzero contact angle to perfect wetting as a critical point is approached, in contrast to Sullivan's original theory, which predicts only a second-order transition. The predictions of this computationally convenient theory are in qualitative agreement with a more rigorous theory to be presented in a future publication

Demographic Disequilibrium in Early Twentieth Century Thailand: Falling Mortality, Rising Fertility, or Both?

Science.gov (United States)

Carmichael, Gordon A

2008-07-17

Estimates of Thai crude birth and death rates date from 1920 when the former was around 20 per thousand higher than the latter, implying natural increase of 2 percent per annum. Such disequilibrium cannot have been the norm over the long term historical past, when population growth must have been comparatively slow. This paper explores the bases for likely past relative equilibrium between Siamese birth and death rates, then seeks to explain the disequilibrium apparent by 1920. Classic demographic transition theory postulates initially high birth and death rates, this equilibrium eventually being broken by falling mortality. In Thailand, however, there is likely to have been both significant mortality decline and appreciable fertility increase after 1850, as the virtual elimination of indigenous warfare, rapid growth of the export rice economy and the demise of slavery and corvée labour created a new domestic environment. Characterized by more dispersed, often frontier, settlement, this environment was unprecedentedly sedate and settled, afforded ordinary households a previously unknown level of control over their resources of labour, and generated optimism about prospects for the next generation.

How does variance in fertility change over the demographic transition?

Science.gov (United States)

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).

Assessment of transition readiness in adolescents and young adults with chronic health conditions.

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Jensen, Paul T; Paul, Gabrielle V; LaCount, Stephanie; Peng, Juan; Spencer, Charles H; Higgins, Gloria C; Boyle, Brendan; Kamboj, Manmohan; Smallwood, Christopher; Ardoin, Stacy P

2017-09-09

Transition from pediatric to adult health care is a vulnerable period for adolescents and young adults. Challenges include paucity of validated measures to assess patients' transition readiness. We evaluated the Transition Readiness Assessment Questionnaire (TRAQ) in adolescents and young adults with rheumatic, gastrointestinal, and endocrine disorders. We examined whether baseline TRAQ scores and other demographic variables predicted transition to adult care over a three year follow up period. In this descriptive study at a single institution, eighty-nine adolescents at a single pediatric academic medical center completed demographic and medical history surveys and the TRAQ and were followed over 3 years by telephone interview to determine whether they had transitioned to adult subspecialty care. Transition was defined as attending at least one adult subspecialty appointment. Multivariable logistic regression and Cox proportional hazards regression models were used to determine whether TRAQ scores predicted time to transition. Of the participants, 56% had rheumatic, 21% endocrine, and 23% gastrointestinal conditions. The TRAQ self-management domain score was not significantly associated with age, gender, socioeconomic status, or specialty. The TRAQ self-advocacy score increased with age. Baseline TRAQ scores did not predict transition or time to transition over three years. In this cohort of adolescents and young adults who were 16 to 23 years of age at enrollment, 48% transitioned to adult care over three years of follow up. Nearly half reported not discussing transition with provider or seeing provider independently for part of visit. Older age but not other demographic variables nor baseline TRAQ score predicted transition or time to transition to an adult subspecialty provider; however, a there was a trend towards shorter time to transition with the highest quartile TRAQ scores.

Ginsburg-Landau equation around the superconductor-insulator transition

International Nuclear Information System (INIS)

Ng, T.K.

1991-01-01

Based on the scaling theory of localization, we construct a Ginsburg-Landau (GL) equation for superconductors in an arbitrary strength of disordered potential. Using this GL equation, we reexamine the criteria for the superconductor-insulator transition and find that the transition to a localized superconductor can happen on both sides of the (normal) metal-insulator transition, in contrast to a previous prediction by Ma and Lee [Phys. Rev. B 32, 5658 (1985)] that the transition can only be on the insulator side. Furthermore, by comparing our theory with a recent scaling theory of dirty bosons by Fisher et al. [Phys. Rev. Lett. 64, 587 (1990)], we conclude that nontrivial crossover behavior in transport properties may occur in the vicinity of the superconductor-insulator transition

The socio-demographic aspects of building social infrastructure in the city of Moscow

Directory of Open Access Journals (Sweden)

Strashnova Yuliya gennad’evna

2018-03-01

Full Text Available Subject: the influence of the socio-demographic factor on the development of the network of facilities of the social infrastructure of the city (on the example of Moscow is explored. The interrelation between socio-demographic development and the formation of the consumer demand for services and various types of facilities is revealed. The main socio-demographic concepts and measures determining a need to develop and site the facilities throughout the city are considered. Thus, the social, age and family structure of the resident population determine the typology and functional structure of facilities. The “daytime” population, its structure and concentration areas determine the volume and the new construction sites of residential buildings. The “temporary” population (including tourists, transit passengers, business travelers and other population categories, staying in the city for more than 24 hours specifies the need for the construction of hotels, hostels and other collective accommodation facilities. Economically active population creates demand for jobs, including those created on the basis of social infrastructure. Objectives: to explain the need for taking into account the modern and perspective trends in population development during the preparation of the territorial and urban planning documents; to consider the particularities of the socio-demographic characteristics included when forecasting the need to develop the social facilities, creating workplaces, taking into account the transition to the economy of services and information technologies, in designing a citywide system, including transport hubs. Materials and methods: the research was conducted on the basis of official statistics (Rosstat, Mosgorstat, of line departments and offices of the city of Moscow. Statistical, analytical, sociological methods of research, expert assessments, analogies, field survey, mathematical modeling are used. Results: modern and perspective

Comment on "Minimum Action Path Theory Reveals the Details of Stochastic Transitions Out of Oscillatory States"

OpenAIRE

Meerson, Baruch; Smith, Naftali R.

2018-01-01

De la Cruz et al. [Phys. Rev. Lett. 120, 128102 (2018); arXiv:1705.08683] studied a noise-induced transition in an oscillating stochastic population undergoing birth- and death-type reactions. They applied the Freidlin-Wentzell WKB formalism to determine the most probable path to the noise-induced escape from a limit cycle predicted by deterministic theory, and to find the probability distribution of escape time. Here we raise a number of objections to their calculations.

Time-Dependent Density Functional Theory Analysis of Triphenylamine-Functionalized Graphene Doped with Transition Metals for Photocatalytic Hydrogen Production.

Science.gov (United States)

Mota, Elder A V; Neto, Abel F G; Marques, Francisco C; Mota, Gunar V S; Martins, Marcelo G; Costa, Fabio L P; Borges, Rosivaldo S; Neto, Antonio M J C

2018-07-01

The electronic structures and optical properties of triphenylamine-functionalized graphene (G-TPA) doped with transition metals, using water as a solvent, were theoretically investigated to verify the efficiency of photocatalytic hydrogen production with the use of transition metals. This study was performed by Density Functional Theory and Time-dependent Density Functional Theory through Gaussian 09W software, adopting the B3LYP functional for all structures. The 6-31g(d) basis set was used for H, C and N atoms, and the LANL2DZ basis set for transition metals using the Effective Core Potentials method. Two approaches were adopted: (1) using single metallic dopants (Ni, Pd, Fe, Os and Pt) and (2) using combinations of Ni with the other dopants (NiPd, NiPt, NiFe and NiOs). The DOS spectra reveal an increase of accessible states in the valence shell, in addition to a gap decrease for all dopants. This doping also increases the absorption in the visible region of solar radiation where sunlight is most intense (400 nm to 700 nm), with additional absorption peaks. The results lead us to propose the G-TPA structures doped with Ni, Pd, Pt, NiPt or NiPd to be novel catalysts for the conversion of solar energy for photocatalytic hydrogen production, since they improve the absorption of solar energy in the range of interest for solar radiation; and act as reaction centers, reducing the required overpotential for hydrogen production from water.

Reassessment of fission fragment angular distributions from continuum states in the context of transition-state theory

International Nuclear Information System (INIS)

Vaz, L.C.; Alexander, J.M.

1983-01-01

Fission angular distributions have been studied for years and have been treated as classic examples of transition-state theory. Early work involving composite nuclei of relatively low excitation energy Esup(*) ( 2 0 (K 2 0 = Psub(eff)T/(h/2π) 2 ) are presented along with comparissons of Psub(eff) to moments of inertia for saddle-point nuclei from the rotating liquid drop model. This model gives an excellent guide for the intermediate spin zone (30 < or approx. I < or approx. 65), while strong shell and/or pairing effects are evident for excitations less than < or approx. 35 MeV. Observations of strong anisotropies for very high-spin systems signal the demise of certain approximations commonly made in the theory, and suggestions are made toward this end. (orig.)

"It's Like a Prison in There": Organizational Fragmentation in a Demographically Diversified Workplace.

Science.gov (United States)

Zak, Michele Wender

1994-01-01

Describes how, when a vehicle maintenance unit of a public transit agency underwent extensive demographic diversification of its workforce, original workers escalated shop talk and horse play as vehicles of internal power struggles, leading to dysfunction and even violence. Argues that management failed to provide for the need for newly diverse…

Theory of the multiphoton cascade transitions with two photon links: comparison of quantum electrodynamical and quantum mechanical approaches

International Nuclear Information System (INIS)

Zalialiutdinov, T; Baukina, Yu; Solovyev, D; Labzowsky, L

2014-01-01

The theory of multiphoton cascade transitions with two-photon links is considered within two different approaches: quantum electrodynamical (QED) and phenomenological quantum mechanical (QM). A problem of regularization of the cascade contributions is investigated in detail. It is argued that the correct regularization should include both initial and intermediate level widths in the singular energy denominators. This result follows both from the QED and from the QM approach. Particular transitions nl → 1s + 2γ with nl = 3s, 4s, 3d, 4d and nl → 1s + 3γ with nl = 3p, 4p are considered as examples. The importance of the proper cascade regularization is also demonstrated. (paper)

Metal-insulator transitions

Science.gov (United States)

Imada, Masatoshi; Fujimori, Atsushi; Tokura, Yoshinori

1998-10-01

Metal-insulator transitions are accompanied by huge resistivity changes, even over tens of orders of magnitude, and are widely observed in condensed-matter systems. This article presents the observations and current understanding of the metal-insulator transition with a pedagogical introduction to the subject. Especially important are the transitions driven by correlation effects associated with the electron-electron interaction. The insulating phase caused by the correlation effects is categorized as the Mott Insulator. Near the transition point the metallic state shows fluctuations and orderings in the spin, charge, and orbital degrees of freedom. The properties of these metals are frequently quite different from those of ordinary metals, as measured by transport, optical, and magnetic probes. The review first describes theoretical approaches to the unusual metallic states and to the metal-insulator transition. The Fermi-liquid theory treats the correlations that can be adiabatically connected with the noninteracting picture. Strong-coupling models that do not require Fermi-liquid behavior have also been developed. Much work has also been done on the scaling theory of the transition. A central issue for this review is the evaluation of these approaches in simple theoretical systems such as the Hubbard model and t-J models. Another key issue is strong competition among various orderings as in the interplay of spin and orbital fluctuations. Experimentally, the unusual properties of the metallic state near the insulating transition have been most extensively studied in d-electron systems. In particular, there is revived interest in transition-metal oxides, motivated by the epoch-making findings of high-temperature superconductivity in cuprates and colossal magnetoresistance in manganites. The article reviews the rich phenomena of anomalous metallicity, taking as examples Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Ru compounds. The diverse phenomena include strong spin and

Operator product expansion in Liouville field theory and Seiberg-type transitions in log-correlated random energy models

Science.gov (United States)

Cao, Xiangyu; Le Doussal, Pierre; Rosso, Alberto; Santachiara, Raoul

2018-04-01

We study transitions in log-correlated random energy models (logREMs) that are related to the violation of a Seiberg bound in Liouville field theory (LFT): the binding transition and the termination point transition (a.k.a., pre-freezing). By means of LFT-logREM mapping, replica symmetry breaking and traveling-wave equation techniques, we unify both transitions in a two-parameter diagram, which describes the free-energy large deviations of logREMs with a deterministic background log potential, or equivalently, the joint moments of the free energy and Gibbs measure in logREMs without background potential. Under the LFT-logREM mapping, the transitions correspond to the competition of discrete and continuous terms in a four-point correlation function. Our results provide a statistical interpretation of a peculiar nonlocality of the operator product expansion in LFT. The results are rederived by a traveling-wave equation calculation, which shows that the features of LFT responsible for the transitions are reproduced in a simple model of diffusion with absorption. We examine also the problem by a replica symmetry breaking analysis. It complements the previous methods and reveals a rich large deviation structure of the free energy of logREMs with a deterministic background log potential. Many results are verified in the integrable circular logREM, by a replica-Coulomb gas integral approach. The related problem of common length (overlap) distribution is also considered. We provide a traveling-wave equation derivation of the LFT predictions announced in a precedent work.

Invalidity of the Fermi liquid theory and magnetic phase transition in quasi-1D dopant-induced armchair-edged graphene nanoribbons

Science.gov (United States)

Hoi, Bui Dinh; Davoudiniya, Masoumeh; Yarmohammadi, Mohsen

2018-04-01

Based on theoretically tight-binding calculations considering nearest neighbors and Green's function technique, we show that the magnetic phase transition in both semiconducting and metallic armchair graphene nanoribbons with width ranging from 9.83 Å to 69.3 Å would be observed in the presence of injecting electrons by doping. This transition is explained by the temperature-dependent static charge susceptibility through calculation of the correlation function of charge density operators. This work showed that charge concentration of dopants in such system plays a crucial role in determining the magnetic phase. A variety of multicritical points such as transition temperatures and maximum susceptibility are compared in undoped and doped cases. Our findings show that there exist two different transition temperatures and maximum susceptibility depending on the ribbon width in doped structures. Another remarkable point refers to the invalidity (validity) of the Fermi liquid theory in nanoribbons-based systems at weak (strong) concentration of dopants. The obtained interesting results of magnetic phase transition in such system create a new potential for magnetic graphene nanoribbon-based devices.

Transition démographique, transition alimentaire. II De la logique démographique à la logique alimentaire

OpenAIRE

Philippe Collomb

1989-01-01

Collomb Philippe. - Demographic transition, transition in nutrition. II. From the logic of population growth to the logic of demand for food. In a world where migrations from poor to rich countries is too limited in scope to reduce social inequalities between peoples, the poor countries, each according to its means, are forced to resort to importing increasingly massive amounts of cereals. The proportion of agricultural producers within the active national population can be used to estimate t...

Density Functional Theory of Open-Shell Systems. The 3d-Series Transition-Metal Atoms and Their Cations.

Science.gov (United States)

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

Role of Fluorescence yields, Coster–Kronig transitions and ionization theories on L X-ray intensity ratios of Au

International Nuclear Information System (INIS)

Mohan, Harsh; Kumar Jain, Arvind; Kaur, Gurpreet; Singh, Parjit S.; Sharma, Sunita

2012-01-01

The inner-shell vacancy decay process is consisting of radiative and non-radiative transitions. These investigations have been developing over the last four decades, resulting in close and stringent comparisons of the measured values with the predictions of theoretical models. In view of the current state of affairs, we report in this paper the role of Fluorescence yields, Coster–Kronig transitions and prevailing ionization theories on L X-ray production from Au using low energy protons. Their contribution to these phenomena and current growth will be highlighted. Prospects for supplementary effort will also be discussed. - Highlights: ► New data for L X-ray production from Au using low energy protons are reported. ► Effects of Fluorescence yields and Coster–Kronig transitions on it are analyzed. ► Stringent comparison of measured values with theoretical models has been presented.► Their contribution to these phenomena and current growth has been highlighted. ► Prospects for supplementary effort are discussed.

A liquid-liquid transition in supercooled aqueous solution related to the HDA-LDA transition

Science.gov (United States)

Woutersen, Sander; Ensing, Bernd; Hilbers, Michiel; Zhao, Zuofeng; Angell, C. Austen

2018-03-01

Simulations and theory suggest that the thermodynamic anomalies of water may be related to a phase transition between two supercooled liquid states, but so far this phase transition has not been observed experimentally because of preemptive ice crystallization. We used calorimetry, infrared spectroscopy, and molecular dynamics simulations to investigate a water-rich hydrazinium trifluoroacetate solution in which the local hydrogen bond structure surrounding a water molecule resembles that in neat water at elevated pressure, but which does not crystallize upon cooling. Instead, this solution underwent a sharp, reversible phase transition between two homogeneous liquid states. The hydrogen-bond structures of these two states are similar to those established for high- and low-density amorphous (HDA and LDA) water. Such structural similarity supports theories that predict a similar sharp transition in pure water under pressure if ice crystallization could be suppressed.

Reformulation of time-convolutionless mode-coupling theory near the glass transition

Science.gov (United States)

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.

Mixing times towards demographic equilibrium in insect populations with temperature variable age structures.

Science.gov (United States)

Damos, Petros

2015-08-01

In this study, we use entropy related mixing rate modules to measure the effects of temperature on insect population stability and demographic breakdown. The uncertainty in the age of the mother of a randomly chosen newborn, and how it is moved after a finite act of time steps, is modeled using a stochastic transformation of the Leslie matrix. Age classes are represented as a cycle graph and its transitions towards the stable age distribution are brought forth as an exact Markov chain. The dynamics of divergence, from a non equilibrium state towards equilibrium, are evaluated using the Kolmogorov-Sinai entropy. Moreover, Kullback-Leibler distance is applied as information-theoretic measure to estimate exact mixing times of age transitions probabilities towards equilibrium. Using empirically data, we show that on the initial conditions and simulated projection's trough time, that population entropy can effectively be applied to detect demographic variability towards equilibrium under different temperature conditions. Changes in entropy are correlated with the fluctuations of the insect population decay rates (i.e. demographic stability towards equilibrium). Moreover, shorter mixing times are directly linked to lower entropy rates and vice versa. This may be linked to the properties of the insect model system, which in contrast to warm blooded animals has the ability to greatly change its metabolic and demographic rates. Moreover, population entropy and the related distance measures that are applied, provide a means to measure these rates. The current results and model projections provide clear biological evidence why dynamic population entropy may be useful to measure population stability. Copyright © 2015 Elsevier Inc. All rights reserved.

Behavior of the antiferromagnetic phase transition near the fermion condensation quantum phase transition in YbRh{sub 2}Si{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Shaginyan, V.R., E-mail: vrshag@thd.pnpi.spb.r [Petersburg Nuclear Physics Institute, RAS, Gatchina 188300 (Russian Federation); Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Amusia, M.Ya. [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Popov, K.G. [Komi Science Center, Ural Division, RAS, Syktyvkar 167982 (Russian Federation)

2010-01-11

Low-temperature specific-heat measurements on YbRh{sub 2}Si{sub 2} at the second order antiferromagnetic (AF) phase transition reveal a sharp peak at T{sub N}=72 mK. The corresponding critical exponent alpha turns out to be alpha=0.38, which differs significantly from that obtained within the framework of the fluctuation theory of second order phase transitions based on the scale invariance, where alphaapprox =0.1. We show that under the application of magnetic field the curve of the second order AF phase transitions passes into a curve of the first order ones at the tricritical point leading to a violation of the critical universality of the fluctuation theory. This change of the phase transition is generated by the fermion condensation quantum phase transition. Near the tricritical point the Landau theory of second order phase transitions is applicable and gives alphaapprox =1/2. We demonstrate that this value of alpha is in good agreement with the specific-heat measurements.

A Definition of the Magnetic Transition Temperature Using Valence Bond Theory.

Science.gov (United States)

Jornet-Somoza, Joaquim; Deumal, Mercè; Borge, Juan; Robb, Michael A

2018-03-01

Macroscopic magnetic properties are analyzed using Valence Bond theory. Commonly the critical temperature T C for magnetic systems is associated with a maximum in the energy-based heat capacity C p (T). Here a more broadly applicable definition of the magnetic transition temperature T C is described using the spin moment expectation value (i.e., applying the spin exchange density operator) instead of energy. Namely, the magnetic capacity C s (T) reflects variation in the spin multiplicity as a function of temperature, which is shown to be related to ∂[χT(T)]/∂T. Magnetic capacity C s (T) depends on long-range spin interactions that are not relevant in the energy-based heat capacity C p (T). Differences between C s (T) and C p (T) are shown to be due to spin order/disorder within the crystal that can be monitored via a Valence Bond analysis of the corresponding magnetic wave function. Indeed the concept of the Boltzmann spin-alignment order is used to provide information about the spin correlation between magnetic units. As a final illustration, the critical temperature is derived from the magnetic capacity for several molecular magnets presenting different magnetic topologies that have been experimentally studied. A systematic shift between the transition temperatures associated with C s (T) and C p (T) is observed. It is demonstrated that this shift can be attributed to the loss of long-range spin correlation. This suggests that the magnetic capacity C s (T) can be used as a predictive tool for the magnetic topology and thus for the synthetic chemists.

Prototyping SOS meta-theory in Maude

NARCIS (Netherlands)

Mousavi, M.R.; Reniers, M.A.; Mosses, P.D.; Ulidowski, I.

2006-01-01

We present a prototype implementation of SOS meta-theory in the Maude term rewriting language. The prototype defines the basic concepts of SOS meta-theory (e.g., transition formulae, deduction rules and transition system specifications) in Maude. Besides the basic definitions, we implement methods

Das causas às conseqüências econômicas da transição demográfica no Brasil From the causes to the economic consequences of the demographic transition in Brazil

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

Center vortex model for the infrared sector of SU(4) Yang-Mills theory: String tensions and deconfinement transition

International Nuclear Information System (INIS)

Engelhardt, M.

2006-01-01

A random vortex world-surface model for the infrared sector of SU(4) Yang-Mills theory is constructed, focusing on the confinement properties and the behavior at the deconfinement phase transition. Although the corresponding data from lattice Yang-Mills theory can be reproduced, the model requires a more complex action and considerably more tuning than the SU(2) and SU(3) cases studied previously. Its predictive capabilities are accordingly reduced. This behavior has a definite physical origin, which is elucidated in detail in the present work. As the number of colors is raised in Yang-Mills theory, the corresponding infrared effective vortex description cannot indefinitely continue to rely on dynamics determined purely by vortex world-surface characteristics; additional color structures present on the vortices begin to play a role. As evidenced by the modeling effort reported here, definite signatures of this behavior appear in the case of four colors

[Doctoral thesis: Demographic growth and economic and social development in Mali].

Science.gov (United States)

Dabo, K

1999-12-01

A doctoral thesis is described analyzing the relationships between demographic growth and economic and social development in Mali. The hypothesis is stated that demographic growth impedes economic development and any improvement in populations¿ standards of living. The hypothesis was verified using data for the period from 1960 to the present. Over that period, Mali conducted two general population censuses in 1976 and 1987, as well as several demographic research studies. The thesis is comprised of 4 parts, of which the first generally describes Mali. The second part analyzes the relationship between population growth and economic and social development in Mali. Study results are presented, followed by an analysis of the effects of economic and social development upon population growth in Mali through factors such as urbanization, education level, literacy, income, employment, occupation, gross domestic or gross national product by inhabitant, infant mortality rate, life expectancy at birth, contraceptive practice, fertility opinions and desires, women¿s status, and migration in Mali. Analysis indicates that Mali has not completely begun its demographic transition, but that traditional pronatalist behaviors are changing. Population policies and programs are explored in the third part of the thesis, followed by the fourth part which focuses upon methodological questions.

Polymorphic phase transitions: Macroscopic theory and molecular simulation.

Science.gov (United States)

Anwar, Jamshed; Zahn, Dirk

2017-08-01

Transformations in the solid state are of considerable interest, both for fundamental reasons and because they underpin important technological applications. The interest spans a wide spectrum of disciplines and application domains. For pharmaceuticals, a common issue is unexpected polymorphic transformation of the drug or excipient during processing or on storage, which can result in product failure. A more ambitious goal is that of exploiting the advantages of metastable polymorphs (e.g. higher solubility and dissolution rate) while ensuring their stability with respect to solid state transformation. To address these issues and to advance technology, there is an urgent need for significant insights that can only come from a detailed molecular level understanding of the involved processes. Whilst experimental approaches at best yield time- and space-averaged structural information, molecular simulation offers unprecedented, time-resolved molecular-level resolution of the processes taking place. This review aims to provide a comprehensive and critical account of state-of-the-art methods for modelling polymorph stability and transitions between solid phases. This is flanked by revisiting the associated macroscopic theoretical framework for phase transitions, including their classification, proposed molecular mechanisms, and kinetics. The simulation methods are presented in tutorial form, focusing on their application to phase transition phenomena. We describe molecular simulation studies for crystal structure prediction and polymorph screening, phase coexistence and phase diagrams, simulations of crystal-crystal transitions of various types (displacive/martensitic, reconstructive and diffusive), effects of defects, and phase stability and transitions at the nanoscale. Our selection of literature is intended to illustrate significant insights, concepts and understanding, as well as the current scope of using molecular simulations for understanding polymorphic

The problem of phase transitions in statistical mechanics

International Nuclear Information System (INIS)

Martynov, Georgii A

1999-01-01

The first part of this review deals with the single-phase approach to the statistical theory of phase transitions. This approach is based on the assumption that a first-order phase transition is due to the loss of stability of the parent phase. We demonstrate that it is practically impossible to find the coordinates of the transition points using this criterion in the framework of the global Gibbs theory which describes the state of the entire macroscopic system. On the basis of the Ornstein-Zernike equation we formulate a local approach that analyzes the state of matter inside the correlation sphere of radius R c ∼ 10 A. This approach is proved to be as rigorous as the Gibbs theory. In the context of the local approach we formulate a criterion that allows finding the transition points without calculating the chemical potential and the pressure of the second conjugate phase. In the second part of the review we consider second-order phase transitions (critical phenomena). The Kadanoff-Wilson theory of critical phenomena is analyzed, based on the global Gibbs approach. Again we use the Ornstein-Zernike equation to formulate a local theory of critical phenomena. With regard to experimentally established quantities this theory yields precisely the same results as the Kadanoff-Wilson theory; secondly, the local approach allows the prediction of many previously unknown details of critical phenomena, and thirdly, the local approach paves the way for constructing a unified theory of liquids that will describe the behavior of matter not only in the regular domain of the phase diagram, but also at the critical point and in its vicinity. (reviews of topical problems)

Impulsive Stimulated Light Scattering Studies of the Liquid-Glass Transition: on the Experimental Verification of Mode-Coupling Theory Predictions.

Science.gov (United States)

Halalay, Ion C.

A study of the structural glass transition trough impulsive stimulated light scattering experiments has been carried out in concentrated aqueous lithium chloride solutions, at temperatures ranging from ambient to cryogenic. A specially designed sample cell made it possible to cover the whole temperature interval from simple liquid, to viscoelastic supercooled liquid, to glass. It is shown that a phenomenological description of the results of these experiments in terms of a spectrum of relaxation times through the use of a Kohlrausch-Williams-Watts relaxation function is inadequate. Based on predictions of mode-coupling theory of the liquid-glass transition, an alternative approach to data interpretation is proposed. It is shown that for an aqueous lithium chloride solution, the prediction of simple scaling and identical scaling for mechanical and electrical susceptibilities seems to be valid. However, another prediction of theory is called into question: instead of a power-law behavior on temperature difference, it is found experimentally that the behavior of the susceptibility spectrum minimum is exponential. Similar disagreements are found for other two materials, triphenyl phosphite and polypropylene oxide. The causes for these discrepancies are discussed and it is concluded that additional experimentation is necessary to verify theoretical claims. Experiments are proposed which can test these predictions and serve as guide for the construction of theoretical models for the glass transition in real systems. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Variational transition state theory for multidimensional activated rate processes in the presence of anisotropic friction

Science.gov (United States)

Berezhkovskii, Alexander M.; Frishman, Anatoli M.; Pollak, Eli

1994-09-01

Variational transition state theory (VTST) is applied to the study of the activated escape of a particle trapped in a multidimensional potential well and coupled to a heat bath. Special attention is given to the dependence of the rate constant on the friction coefficients in the case of anisotropic friction. It is demonstrated explicitly that both the traditional as well as the nontraditional scenarios for the particle escape are recovered uniformly within the framework of VTST. Effects such as saddle point avoidance and friction dependence of the activation energy are derived from VTST using optimized planar dividing surfaces.

Dynamic Transition and Pattern Formation in Taylor Problem

Institute of Scientific and Technical Information of China (English)

Tian MA; Shouhong WANG

2010-01-01

The main objective of this article is to study both dynamic and structural transitions of the Taylor-Couette flow,by using the dynamic transition theory and geometric theory of incompressible flows developed recently by the authors.In particular,it is shown that as the Taylor number crosses the critical number,the system undergoes either a continuous or a jump dynamic transition,dictated by the sign of a computable,nondimensional parameter R.In addition,it is also shown that the new transition states have the Taylor vortex type of flow structure,which is structurally stable.

Refined geometric transition and qq-characters

Science.gov (United States)

Kimura, Taro; Mori, Hironori; Sugimoto, Yuji

2018-01-01

We show the refinement of the prescription for the geometric transition in the refined topological string theory and, as its application, discuss a possibility to describe qq-characters from the string theory point of view. Though the suggested way to operate the refined geometric transition has passed through several checks, it is additionally found in this paper that the presence of the preferred direction brings a nontrivial effect. We provide the modified formula involving this point. We then apply our prescription of the refined geometric transition to proposing the stringy description of doubly quantized Seiberg-Witten curves called qq-characters in certain cases.

A succession of theories: purging redundancy from disturbance theory.

Science.gov (United States)

Pulsford, Stephanie A; Lindenmayer, David B; Driscoll, Don A

2016-02-01

The topics of succession and post-disturbance ecosystem recovery have a long and convoluted history. There is extensive redundancy within this body of theory, which has resulted in confusion, and the links among theories have not been adequately drawn. This review aims to distil the unique ideas from the array of theory related to ecosystem change in response to disturbance. This will help to reduce redundancy, and improve communication and understanding between researchers. We first outline the broad range of concepts that have developed over the past century to describe community change in response to disturbance. The body of work spans overlapping succession concepts presented by Clements in 1916, Egler in 1954, and Connell and Slatyer in 1977. Other theories describing community change include state and transition models, biological legacy theory, and the application of functional traits to predict responses to disturbance. Second, we identify areas of overlap of these theories, in addition to highlighting the conceptual and taxonomic limitations of each. In aligning each of these theories with one another, the limited scope and relative inflexibility of some theories becomes apparent, and redundancy becomes explicit. We identify a set of unique concepts to describe the range of mechanisms driving ecosystem responses to disturbance. We present a schematic model of our proposed synthesis which brings together the range of unique mechanisms that were identified in our review. The model describes five main mechanisms of transition away from a post-disturbance community: (i) pulse events with rapid state shifts; (ii) stochastic community drift; (iii) facilitation; (iv) competition; and (v) the influence of the initial composition of a post-disturbance community. In addition, stabilising processes such as biological legacies, inhibition or continuing disturbance may prevent a transition between community types. Integrating these six mechanisms with the functional

Extending Modal Transition Systems with Structured Labels

DEFF Research Database (Denmark)

Bauer, Sebastian S.; Juhl, Line; Larsen, Kim Guldstrand

2012-01-01

We introduce a novel formalism of label-structured modal transition systems that combines the classical may/must modalities on transitions with structured labels that represent quantitative aspects of the model. On the one hand, the specification formalism is general enough to include models like...... weighted modal transition systems and allows the system developers to employ more complex label refinement than in the previously studied theories. On the other hand, the formalism maintains the desirable properties required by any specification theory supporting compositional reasoning. In particular, we...

Transitional Labour Markets: Past, Present and Future Applications

NARCIS (Netherlands)

Mooi-Reci, I.; de Bruijn, J.G.M.

2006-01-01

Over the past years many researchers have used the theory of transitional labour markets (TLM theory), grounded by Günther Schmid (1998), as a framework from where they could organize and analyze transitions in and around the labour market. However, the literature lacks a review that organizes and

Entrepreneurship Education: How Psychological, Demographic and Behavioural Factors Predict the Entrepreneurial Intention

Science.gov (United States)

Marques, Carla S.; Ferreira, Joao J.; Gomes, Daniela N.; Rodrigues, Ricardo Gouveia

2012-01-01

Purpose: Based on the Theory of Planned Behaviour (TPB), the purpose of this paper is to approach entrepreneurial intention (EI) and the factors preceding the founding of EI among secondary students, both studying general academic and specific professional programs, and thereby establish causal relationships between psychological, demographic and…

Supersymmetric phase transition in Josephson-tunnel-junction arrays

Energy Technology Data Exchange (ETDEWEB)

Foda, O.

1988-08-31

The fully frustrated XY model in two dimensions exhibits a vortex-unbinding as well as an Ising transition. If the Ising transition overlaps with the critical line that ends on the vortex transition: T/sub I/less than or equal toT/sub V/, then the model is equivalent, at the overlap temperature, to a free massless field theory of 1 boson and 1 Majorana fermion, which is a superconformal field theory, of central charge c=3/2. The model is experimentally realized in terms of an array of Josephson-tunnel junctions in a transverse magnetic field. The experiment reveals a phase transition consistent with T/sub I/=T/sub V/. Thus, at the critical temperature, the array provides a physical realization of a supersymmetric quantum field theory.

The demographic changes of the last quarter of century in Romania

Directory of Open Access Journals (Sweden)

Adriana Veronica LITRA

2015-12-01

Full Text Available The year 1990 has delimited two different demographic periods in Romania: the first, defined as Stage 2 in the Demographic Transition Model (as in Population Education, USA, characterized by low mortality rates due to advances in medical, and high birth rates, resulting rapid population growth; after 1990, Romania moved to Stage 5, having a negative growth rate due to less births than deaths, and a negative net migration rate. Romania is experiencing a falling population with birth rates at 8.3 births per 1,000 persons and death rates at 11.4 per 1,000 persons in 2014. The total fertility rate fell significantly below the replacement level of generations (1.4 live births per woman in 2014, reversing the proportion of elderly in detriment of the youth.

Phase transitions and flux distributions of SU(2) lattice gauge theory

International Nuclear Information System (INIS)

Peng, Yingcai.

1993-01-01

The strong interactions between quarks are believed to be described by Quantum Chromodynamics (QCD), which is a non-abelian SU(3) gauge theory. It is known that QCD undergoes a deconfining phase transition at very high temperatures, that is, at low temperatures QCD is in confined phase, at sufficient high temperatures it is in an unconfined phase. Also, quark confinement is believed to be due to string formation. In this dissertation the authors studied SU(2) gauge theory using numerical methods of LGT, which will provide some insights about the properties of QCD because SU(2) is similar to SU(3). They measured the flux distributions of a q bar q pair at various temperatures in different volumes. They find that in the limit of infinite volumes the flux distribution is different in the two phases. In the confined phase strong evidence is found for the string formation, however, in the unconfined phase there is no string formation. On the other hand, in the limit of zero temperature and finite volumes they find a clear signal for string formation in the large volume region, however, the string tension measured in intermediate volumes is due to finite volume effects, there is no intrinsic string formation. The color flux energies (action) of the q bar q pair are described by Michael sum rules. The original Michael sum rules deal with a static q bar q pair at zero temperature in infinite volumes. To check these sum rules with flux data at finite temperatures, they present a complete derivation for the sum rules, thus generalizing them to account for finite temperature effects. They find that the flux data are consistent with the prediction of generalized sum rules. The study elucidates the rich structures of QCD, and provides evidence for quark confinement and string formation. This supports the belief that QCD is a correct theory for strong interactions, and quark confinement can be explained by QCD

Transition-Systems, Event Structures, and Unfoldings

DEFF Research Database (Denmark)

Nielsen, Mogens; Rozenberg, Grzegorz; Thiagarajan, P.S.

1995-01-01

systems. Here we show that by smoothly strengthening the regional axioms for elementary transition systems, one obtains a subclass called occurrence transition system. We then prove that occurrence transition systems are the transition system model of yet another basic model of concurrency, namely, prime......A subclass of transition systems called elementary transition systems can be identified with the help of axioms based on a structural notion called regions. Elementary transition systems have been shown to be the transition system model of a basic system model of net theory called elementary net...

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.

Theory of Valence Transitions in Ytterbium and Europium Intermetallics

International Nuclear Information System (INIS)

Zlatic, V.; Freericks, J.K.

2001-01-01

The exact solution of the multi-component Falicov-Kimball model in infinite-dimensions is presented and used to discuss a new fixed point of valence fluctuating intermetallics with Yb and Eu ions. In these compounds, temperature, external magnetic field, pressure, or chemical pressure induce a transition between a metallic state with the f-ions in a mixed-valent (non-magnetic) configuration and a semi-metallic state with the f-ions in an integral-valence (paramagnetic) configuration. The zero-field transition occurs at the temperature T V , while the zero-temperature transition sets in at the critical field H c . We present the thermodynamic and dynamic properties of the model for an arbitrary concentration of d- and f -electrons. For large U, we find a MI transition, triggered by the temperature or field- induced change in the f-occupancy. (author)

Direct simulation of groundwater transit-time distributions using the reservoir theory

Science.gov (United States)

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

Intensive care survivors' experiences of ward-based care: Meleis' theory of nursing transitions and role development among critical care outreach services.

Science.gov (United States)

Ramsay, Pam; Huby, Guro; Thompson, Andrew; Walsh, Tim

2014-03-01

To explore the psychosocial needs of patients discharged from intensive care, the extent to which they are captured using existing theory on transitions in care and the potential role development of critical care outreach, follow-up and liaison services. Intensive care patients are at an increased risk of adverse events, deterioration or death following ward transfer. Nurse-led critical care outreach, follow-up or liaison services have been adopted internationally to prevent these potentially avoidable sequelae. The need to provide patients with psychosocial support during the transition to ward-based care has also been identified, but the evidence base for role development is currently limited. Twenty participants were invited to discuss their experiences of ward-based care as part of a broader study on recovery following prolonged critical illness. Psychosocial distress was a prominent feature of their accounts, prompting secondary data analysis using Meleis et al.'s mid-range theory on experiencing transitions. Participants described a sense of disconnection in relation to profound debilitation and dependency and were often distressed by a perceived lack of understanding, indifference or insensitivity among ward staff to their basic care needs. Negotiating the transition between dependence and independence was identified as a significant source of distress following ward transfer. Participants varied in the extent to which they were able to express their needs and negotiate recovery within professionally mediated boundaries. These data provide new insights into the putative origins of the psychosocial distress that patients experience following ward transfer. Meleis et al.'s work has resonance in terms of explicating intensive care patients' experiences of psychosocial distress throughout the transition to general ward-based care, such that the future role development of critical care outreach, follow-up and liaison services may be more theoretically informed

Dynamical Mean Field Approximation Applied to Quantum Field Theory

CERN Document Server

Akerlund, Oscar; Georges, Antoine; Werner, Philipp

2013-12-04

We apply the Dynamical Mean Field (DMFT) approximation to the real, scalar phi^4 quantum field theory. By comparing to lattice Monte Carlo calculations, perturbation theory and standard mean field theory, we test the quality of the approximation in two, three, four and five dimensions. The quantities considered in these tests are the critical coupling for the transition to the ordered phase and the associated critical exponents nu and beta. We also map out the phase diagram in four dimensions. In two and three dimensions, DMFT incorrectly predicts a first order phase transition for all bare quartic couplings, which is problematic, because the second order nature of the phase transition of lattice phi^4-theory is crucial for taking the continuum limit. Nevertheless, by extrapolating the behaviour away from the phase transition, one can obtain critical couplings and critical exponents. They differ from those of mean field theory and are much closer to the correct values. In four dimensions the transition is sec...

First order electroweak phase transition

International Nuclear Information System (INIS)

Buchmueller, W.; Fodor, Z.

1993-01-01

In this work, the authors have studied the phase transition in the SU(2)gauge theory at finite temperature. The authors' improved perturbative approach does not suffer from the infrared problems appearing in the ordinary loop expansion. The authors have calculated the effective potential up to cubic terms in the couplings. The higher order terms suggest that the method is reliable for Higgs masses smaller than 80 GeV. The authors have obtained a non-vanishing magnetic mass which further weakens the transitions. By use of Langer's theory of metastability, the authors have calculated the nucleation rate for critical bubbles and have discussed some cosmological consequences. For m H <80 GeV the phase transition is first order and proceeds via bubble nucleation and growth. The thin wall approximation is only marginally applicable. Since the phase transition is quite weak SM baryogenesis is unlikely. 8 refs., 5 figs

Exploring the Impact of Commuter’s Residential Location Choice on the Design of a Rail Transit Line Based on Prospect Theory

Directory of Open Access Journals (Sweden)

Ding Liu

2014-01-01

Full Text Available This paper explores the impact of prospect theory based commuter’s residential location choice on the design problem of a rail transit line located in a monocentric city. A closed-form social welfare maximization model is proposed, with special consideration given to prospect theory based commuter’s residential location choice over years. Commuters are assumed to make residential location choice by a trade-off between daily housing rent and generalized travel cost to minimize their prospect values. The solutions properties of the proposed model are explored and compared analytically. It is found that overestimation exists for the optimal solutions of rail line length, headway, and fare based on traditional utility theory, compared with the optimal solutions of the proposed prospect theory based model. A numerical example is given to illustrate the properties of the proposed model.

A supersymmetric phase transition in Josephson-tunnel-junction arrays

International Nuclear Information System (INIS)

Foda, O.

1988-01-01

The fully frustrated XY model in two dimensions exhibits a vortex-unbinding as well as an Ising transition. If the Ising transition overlaps with the critical line that ends on the vortex transition: T I ≤T V , then the model is equivalent, at the overlap temperature, to a free massless field theory of 1 boson and 1 Majorana fermion, which is a superconformal field theory, of central charge c=3/2. The model is experimentally realized in terms of an array of Josephson-tunnel junctions in a transverse magnetic field. The experiment reveals a phase transition consistent with T I =T V . Thus, at the critical temperature, the array provides a physical realization of a supersymmetric quantum field theory. (orig.)

Filling- and interaction-driven Mott transition. Quantum cluster calculations within self-energy-functional theory; Fuellungs- und wechselwirkungsabhaengiger Mott-Uebergang. Quanten-Cluster-Rechnungen im Rahmen der Selbstenergiefunktional-Theorie

Energy Technology Data Exchange (ETDEWEB)

Balzer, Matthias

2008-07-01

The central goal of this thesis is the examination of strongly correlated electron systems on the basis of the two-dimensional Hubbard model. We analyze how the properties of the Mott insulator change upon doping and with interaction strength. The numerical evaluation is done using quantum cluster approximations, which allow for a thermodynamically consistent description of the ground state properties. The framework of self-energy-functional theory offers great flexibility for the construction of cluster approximations. A detailed analysis sheds light on the quality and the convergence properties of different cluster approximations within the self-energy-functional theory. We use the one-dimensional Hubbard model for these examinations and compare our results with the exact solution. In two dimensions the ground state of the particle-hole symmetric model at half-filling is an antiferromagnetic insulator, independent of the interaction strength. The inclusion of short-range spatial correlations by our cluster approach leads to a considerable improvement of the antiferromagnetic order parameter as compared to dynamical mean-field theory. In the paramagnetic phase we furthermore observe a metal-insulator transition as a function of the interaction strength, which qualitatively differs from the pure mean-field scenario. Starting from the antiferromagnetic Mott insulator a filling-controlled metal-insulator transition in a paramagnetic metallic phase can be observed. Depending on the cluster approximation used an antiferromagnetic metallic phase may occur at first. In addition to long-range antiferromagnetic order, we also considered superconductivity in our calculations. The superconducting order parameter as a function of doping is in good agreement with other numerical methods, as well as with experimental results. (orig.)

Introduction to percolation theory

CERN Document Server

Stauffer, Dietrich

1991-01-01

Percolation theory deals with clustering, criticallity, diffusion, fractals, phase transitions and disordered systems. This book covers the basic theory for the graduate, and also professionals dealing with it for the first time

Effects of demographic structure on key properties of stochastic density-independent population dynamics.

Science.gov (United States)

Vindenes, Yngvild; Sæther, Bernt-Erik; Engen, Steinar

2012-12-01

The development of stochastic demography has largely been based on age structured populations, although other types of demographic structure, especially permanent and dynamic heterogeneity, are likely common in natural populations. The combination of stochasticity and demographic structure is a challenge for analyses of population dynamics and extinction risk, because the population structure will fluctuate around the stable structure and the population size shows transient fluctuations. However, by using a diffusion approximation for the total reproductive value, density-independent dynamics of structured populations can be described with only three population parameters: the expected population growth rate, the environmental variance and the demographic variance. These parameters depend on population structure via the state-specific vital rates and transition rates. Once they are found, the diffusion approximation represents a substantial reduction in model complexity. Here, we review and compare the key population parameters across a wide range of demographic structure, from the case of no structure to the most general case of dynamic heterogeneity, and for both discrete and continuous types. We focus on the demographic variance, but also show how environmental stochasticity can be included. This study brings together results from recent models, each considering a specific type of population structure, and places them in a general framework for structured populations. Comparison across different types of demographic structure reveals that the reproductive value is an essential concept for understanding how population structure affects stochastic dynamics and extinction risk. Copyright © 2011 Elsevier Inc. All rights reserved.

Semiclassical scattering in Yang-Mills theory

International Nuclear Information System (INIS)

Gould, T.M.; Poppitz, E.R.

1994-01-01

A classical solution to the Yang-Mills theory is given a semiclassical interpretation. The boundary value problem on a complex time contour which arises from the semiclassical approximation to multiparticle scattering amplitudes is reviewed and applied to the case of Yang-Mills theory. The solution describes a classically forbidden transition between states with a large average number of particles in the limit g→0. It dominates a transition probability with a semiclassical suppression factor equal to twice the action of the well-known BPST instanton. Hence, it is relevant to the problem of high-energy tunnelling. It describes transitions of unit topological charge for an appropriate time contour. Therefore, it may have a direct interpretation in terms of fermion-number violating processes in electroweak theory. The solution describes a transition between an initial state with parametrically fewer particles than the final state. Thus, it may be relevant to the study of semiclassical initial-state corrections in the limit of a small number of initial particles. The implications of these results for multiparticle production in electroweak theory are also discussed. (orig.)

Aging and demographic plasticity in response to experimental age structures in honeybees (Apis mellifera L).

Science.gov (United States)

Rueppell, Olav; Linford, Robyn; Gardner, Preston; Coleman, Jennifer; Fine, Kari

2008-08-01

Honeybee colonies are highly integrated functional units characterized by a pronounced division of labor. Division of labor among workers is mainly age-based, with younger individuals focusing on in-hive tasks and older workers performing the more hazardous foraging activities. Thus, experimental disruption of the age composition of the worker hive population is expected to have profound consequences for colony function. Adaptive demography theory predicts that the natural hive age composition represents a colony-level adaptation and thus results in optimal hive performance. Alternatively, the hive age composition may be an epiphenomenon, resulting from individual life history optimization. We addressed these predictions by comparing individual worker longevity and brood production in hives that were composed of a single age cohort, two distinct age cohorts, and hives that had a continuous, natural age distribution. Four experimental replicates showed that colonies with a natural age composition did not consistently have a higher life expectancy and/or brood production than the single cohort or double cohort hives. Instead, a complex interplay of age structure, environmental conditions, colony size, brood production, and individual mortality emerged. A general trade-off between worker life expectancy and colony productivity was apparent, and the transition from in-hive tasks to foraging was the most significant predictor of worker lifespan irrespective of the colony age structure. We conclude that the natural age structure of honeybee hives is not a colony-level adaptation. Furthermore, our results show that honeybees exhibit pronounced demographic plasticity in addition to behavioral plasticity to react to demographic disturbances of their societies.

Periodic-orbit formula for quantum reactions through transition states

NARCIS (Netherlands)

Schubert, Roman; Waalkens, Holger; Goussev, Arseni; Wiggins, Stephen

2010-01-01

Transition state theory forms the basis of computing reaction rates in chemical and other systems. Recently, it has been shown how transition state theory can rigorously be realized in phase space by using an explicit algorithm. The quantization has been demonstrated to lead to an efficient

The politics of transition governance in Dutch agriculture: conceptual understanding and implications for transition management

NARCIS (Netherlands)

Grin, J.

2012-01-01

There has been scholarly criticism that transition theory has hitherto largely neglected the politics involved in transition governance. This article offers an analytical framework for understanding powering and legitimisation in a way that does not a priori assume that such politics is bound to

Lattice gauge theory

International Nuclear Information System (INIS)

Mack, G.

1982-01-01

After a description of a pure Yang-Mills theory on a lattice, the author considers a three-dimensional pure U(1) lattice gauge theory. Thereafter he discusses the exact relation between lattice gauge theories with the gauge groups SU(2) and SO(3). Finally he presents Monte Carlo data on phase transitions in SU(2) and SO(3) lattice gauge models. (HSI)

What's so local about global climate change? Testing social theories of environmental degradation to quantify the demographic, economic, and governmental factors associated with energy consumption and carbon dioxide emissions in U.S. metropolitan areas and counties

Science.gov (United States)

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

Transition operators in acoustic-wave diffraction theory. I - General theory. II - Short-wavelength behavior, dominant singularities of Zk0 and Zk0 exp -1

Science.gov (United States)

Hahne, G. E.

1991-01-01

A formal theory of the scattering of time-harmonic acoustic scalar waves from impenetrable, immobile obstacles is established. The time-independent formal scattering theory of nonrelativistic quantum mechanics, in particular the theory of the complete Green's function and the transition (T) operator, provides the model. The quantum-mechanical approach is modified to allow the treatment of acoustic-wave scattering with imposed boundary conditions of impedance type on the surface (delta-Omega) of an impenetrable obstacle. With k0 as the free-space wavenumber of the signal, a simplified expression is obtained for the k0-dependent T operator for a general case of homogeneous impedance boundary conditions for the acoustic wave on delta-Omega. All the nonelementary operators entering the expression for the T operator are formally simple rational algebraic functions of a certain invertible linear radiation impedance operator which maps any sufficiently well-behaved complex-valued function on delta-Omega into another such function on delta-Omega. In the subsequent study, the short-wavelength and the long-wavelength behavior of the radiation impedance operator and its inverse (the 'radiation admittance' operator) as two-point kernels on a smooth delta-Omega are studied for pairs of points that are close together.

Demographic influences on environmental value orientations and normative beliefs about national forest management

Science.gov (United States)

Jerry J. Vaske; Maureen P. Donnelly; Daniel R. Williams; Sandra Jonker

2001-01-01

Using the cognitive hierarchy as the theoretical foundation, this article examines the predictive influence of individuals' demographic characteristics on environmental value orientations and normative beliefs about national forest management. Data for this investigation were obtained from a random sample of Colorado residents (n = 960). As predicted by theory, a...

Isotropic-nematic transition in a mixture of hard spheres and hard spherocylinders: scaled particle theory description

Directory of Open Access Journals (Sweden)

M.F. Holovko

2017-12-01

Full Text Available The scaled particle theory is developed for the description of thermodynamical properties of a mixture of hard spheres and hard spherocylinders. Analytical expressions for free energy, pressure and chemical potentials are derived. From the minimization of free energy, a nonlinear integral equation for the orientational singlet distribution function is formulated. An isotropic-nematic phase transition in this mixture is investigated from the bifurcation analysis of this equation. It is shown that with an increase of concentration of hard spheres, the total packing fraction of a mixture on phase boundaries slightly increases. The obtained results are compared with computer simulations data.

Density-functional theory for f-electron systems. The α-γ phase transition in cerium

International Nuclear Information System (INIS)

Casadei, Marco

2013-01-01

Rare earths are technologically important and scientifically highly interesting elements. The description of the volume collapse exhibited by some rare earth metals poses a great challenge to density-functional theory (DFT) since local/semi-local functionals (LDA/GGA) only partially capture the associated phase transitions. In this work this problem is approached by treating all electrons at the same quantum mechanical level, using both hybrid functionals (e.g. PBE0 and HSE06) and exact-exchange plus correlation in the random-phase approximation (EX+cRPA). The performance of recently developed beyond RPA schemes is also assessed. The isostructural α-γ phase transition in cerium is the most studied. The exact exchange contribution in PBE0 and HSE06 is crucial to produce two distinct solutions that can be associated with the α and γ phases. The two solutions emerge in bulk as well as in cluster calculations. Most notable is their presence in the cerium dimer. However, quantitative agreement with the extrapolated phase diagram requires EX+cRPA. So far the EX+cRPA correction can only be applied to cerium clusters and not to the bulk. A cluster of 19 atoms cut from the fcc crystal structure (the same that characterizes the α and γ phases) was therefore determined as representative. (EX+cRPA) rate at PBE0 for Ce 19 provides good agreement with the extrapolated transition pressure to zero temperature. We predict that a pressure induced phase transition should exist at or close to zero. A finite temperature phase diagram can be drawn in reasonable agreement with experiment by adding entropic effects. The cerium neighbors are also studied: lanthanum, which has no f electrons, praseodymium, with three f electrons and a volume collapse, and neodymium, with four f electrons and no volume collapse. Multiple solutions are also present for these f electron elements, confirming the importance of exact-exchange for f electron systems.

Simulating Valence-to-Core X-ray Emission Spectroscopy of Transition Metal Complexes with Time-Dependent Density Functional Theory.

Science.gov (United States)

Zhang, Yu; Mukamel, Shaul; Khalil, Munira; Govind, Niranjan

2015-12-08

Valence-to-core (VtC) X-ray emission spectroscopy (XES) has emerged as a powerful technique for the structural characterization of complex organometallic compounds in realistic environments. Since the spectrum represents electronic transitions from the ligand molecular orbitals to the core holes of the metal centers, the approach is more chemically sensitive to the metal-ligand bonding character compared with conventional X-ray absorption techniques. In this paper we study how linear-response time-dependent density functional theory (LR-TDDFT) can be harnessed to simulate K-edge VtC X-ray emission spectra reliably. LR-TDDFT allows one to go beyond the single-particle picture that has been extensively used to simulate VtC-XES. We consider seven low- and high-spin model complexes involving chromium, manganese, and iron transition metal centers. Our results are in good agreement with experiment.

Theoretical and expert system approach to photoionization theories

Directory of Open Access Journals (Sweden)

Petrović Ivan D.

2016-01-01

Full Text Available The influence of the ponderomotive and the Stark shifts on the tunneling transition rate was observed, for non-relativistic linearly polarized laser field for alkali atoms, with three different theoretical models, the Keldysh theory, the Perelomov, Popov, Terent'ev (PPT theory, and the Ammosov, Delone, Krainov (ADK theory. We showed that aforementioned shifts affect the transition rate differently for different approaches. Finally, we presented a simple expert system for analysis of photoionization theories.

Geometric transitions on non-Kaehler manifolds

International Nuclear Information System (INIS)

Knauf, A.

2007-01-01

We study geometric transitions on the supergravity level using the basic idea of an earlier paper (M. Becker et al., 2004), where a pair of non-Kaehler backgrounds was constructed, which are related by a geometric transition. Here we embed this idea into an orientifold setup. The non-Kaehler backgrounds we obtain in type IIA are non-trivially fibered due to their construction from IIB via T-duality with Neveu-Schwarz flux. We demonstrate that these non-Kaehler manifolds are not half-flat and show that a symplectic structure exists on them at least locally. We also review the construction of new non-Kaehler backgrounds in type I and heterotic theory. They are found by a series of T- and S-duality and can be argued to be related by geometric transitions as well. A local toy model is provided that fulfills the flux equations of motion in IIB and the torsional relation in heterotic theory, and that is consistent with the U-duality relating both theories. For the heterotic theory we also propose a global solution that fulfills the torsional relation because it is similar to the Maldacena-Nunez background. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

Social-cognitive predictors of vocational outcomes in transition youth with epilepsy: Application of social cognitive career theory.

Science.gov (United States)

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).

Evidence of quantum phase transition in real-space vacuum entanglement of higher derivative scalar quantum field theories.

Science.gov (United States)

Kumar, S Santhosh; Shankaranarayanan, S

2017-11-17

In a bipartite set-up, the vacuum state of a free Bosonic scalar field is entangled in real space and satisfies the area-law- entanglement entropy scales linearly with area of the boundary between the two partitions. In this work, we show that the area law is violated in two spatial dimensional model Hamiltonian having dynamical critical exponent z = 3. The model physically corresponds to next-to-next-to-next nearest neighbour coupling terms on a lattice. The result reported here is the first of its kind of violation of area law in Bosonic systems in higher dimensions and signals the evidence of a quantum phase transition. We provide evidence for quantum phase transition both numerically and analytically using quantum Information tools like entanglement spectra, quantum fidelity, and gap in the energy spectra. We identify the cause for this transition due to the accumulation of large number of angular zero modes around the critical point which catalyses the change in the ground state wave function due to the next-to-next-to-next nearest neighbor coupling. Lastly, using Hubbard-Stratanovich transformation, we show that the effective Bosonic Hamiltonian can be obtained from an interacting fermionic theory and provide possible implications for condensed matter systems.

The Relationship of Dynamical Heterogeneity to the Adam-Gibbs and Random First-Order Transition Theories of Glass Formation

OpenAIRE

Starr, Francis W.; Douglas, Jack F.; Sastry, Srikanth

2013-01-01

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 stri...

Predecessor-Successor Transitions in Institutional and Interpersonal Contexts. On the Development of a Theory of the Transfer of Personal Objects

Directory of Open Access Journals (Sweden)

Franz Breuer

2011-03-01

Full Text Available This article outlines the development of a theory of predecessor-successor transitions in social contexts using a grounded theory approach. The theory can be applied to such diverse phenomena as the transfer of family businesses to the next generation, university chair succession, the passing on of parental roles (for example in the case of adoption or remarriage, and organ transplantation. The core conceptual category that emerged was "the transfer of personal objects". This concept refers to the transfer of the power of disposal over objects that are fundamental to the identity and the identification of the owner. A number of theoretical dimensions of the category were identified. Methodologically speaking, the theory generated can be classified as a formal grounded theory. In other words, the comparison of different empirical fields and cases using hermeneutical analysis yielded a transdisciplinary social science category that can be employed to conceptualise the dynamics of the development of interpersonal, social, or institutional structures, especially with regard to the links and the interplay between material and symbolic components, between the individual and the social, and the past and the present. URN: http://nbn-resolving.de/urn:nbn:de:0114-fqs1102165

Housing Trajectories for Youth Transitioning from Foster Care: Gender Differences from 2010-2014.

Science.gov (United States)

Hasson, Robert G Iii; Reynolds, Andrew D; Crea, Ihomas M

This study focuses on longitudinal housing trends for males and females among transitional youth who were participants of a transitional living program (2010 to 2014). Results indicate that young women were more likely to transition to secure independent housing than young men. Demographic characteristics, education, and employment predicted time to secure independent housing. Additionally, results indicate that more highly educated young women transitioned to independence at a faster rate than young men with lower education status.

Readers' Trust, Socio-Demographic, and Acuity Influences in Citizen Journalism Credibility for Disrupted Online Newspapers

Science.gov (United States)

Wester, Aaron Micah

2013-01-01

The purpose of this quantitative research study was to evaluate and determine if significant associations and linear correlations exist between reader socio-demographics, levels of trust and affinity in online citizen writer news story article content, brand loyalty, and acuity in newspaper organizations transitioning from print to online in a…

Surface hopping, transition state theory, and decoherence. II. Thermal rate constants and detailed balance

Energy Technology Data Exchange (ETDEWEB)

Jain, Amber; Subotnik, Joseph E., E-mail: subotnik@sas.upenn.edu [Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104 (United States)

2015-10-07

We investigate a simple approach to compute a non-adiabatic thermal rate constant using the fewest switches surface hopping (FSSH) dynamics. We study the effects of both decoherence (using our augmented-FSSH (A-FSSH) algorithm) and forbidden hops over a large range of parameters, including high and low friction regimes, and weak and strong electronic coupling regimes. Furthermore, when possible, we benchmark our results against exact hierarchy equations of motion results, where we usually find a maximum error of roughly a factor of two (at reasonably large temperatures). In agreement with Hammes-Schiffer and Tully, we find that a merger of transition state theory and surface hopping can be both accurate and efficient when performed correctly. We further show that detailed balance is followed approximately by A-FSSH dynamics.

Health Related Quality of Life and Its Socio-Demographic Determinants among Iranian Elderly People: a Population Based Cross-Sectional Study

Directory of Open Access Journals (Sweden)

Karimollah Hajian-Tilaki

2017-03-01

Full Text Available Introduction: In the stage of demographic transition, the rate of elderly is increasing and their health condition is a matter of concern. Thus, the objective of this study was to investigate the health related quality of life (QoL and the associated socio-demographic determinants among Iranian elderly people. Methods: We conducted a cross-sectional study with a representative samples of 750 elderly people whom community dwelling in urban area of Babol, in the north of Iran. In a household survey, the demographic data were collected and the health related QoL was assessed with a validated standard short form questionnaire (SF-36. The multiple linear regression analysis was performed to determine the demographic characteristics in predicting QoL using SPSS ver 13. Results: The overall mean (SD scores of QoL was 62.4(17.2 for men and 51.2 (17.9 for women. The mean scores of QoL in all dimensions in men had significantly higher than women. The adjusted regression coefficient of gender, age, educational level, being couple were significant on overall scores of QoL. Aging is inversely associated while male gender and education at high school or higher and being couple are positively associated in prediction of overall scores of QoL. Conclusion: The findings indicate that the health related QoL is rather poor in old people particular in women, elderly with low education level and being single. Therefore, healthcare policy makers should consider an urgent health interventional program among elderly people at present stage of demographic transition with emphasis on high risk demographic profiles.

A harmonic transition state theory model for defect initiation in crystals

International Nuclear Information System (INIS)

Delph, T J; Cao, P; Park, H S; Zimmerman, J A

2013-01-01

We outline here a model for the initiation of defects in crystals based upon harmonic transition state theory (hTST). This model combines a previously developed model for zero-temperature defect initiation with a multi-dimensional hTST model that is capable of accurately predicting the effects of temperature and loading rate upon defect initiation. The model has several features that set it apart from previous efforts along these lines, most notably a straightforward method of determining the energy barrier between adjacent equilibrium states that does not depend upon a priori information concerning the nature of the defect. We apply the model to two examples, triaxial stretching of a perfect fcc crystal and nanoindentation of a gold substrate. Very good agreement is found between the predictions of the model and independent molecular dynamics (MD) simulations. Among other things, the model predicts a strong dependence of the defect initiation behavior upon the loading parameter. A very attractive feature of this model is that it is valid for arbitrarily slow loading rates, in particular loading rates achievable in the laboratory, and suffers from none of the limitations in this regard inherent in MD simulations. (paper)

Transitions to Adulthood and Generational Change in Portugal

Directory of Open Access Journals (Sweden)

Vasco Ramos

2018-04-01

Full Text Available Much of the research on contemporary youth in Western societies has shown that transitions to adulthood are being postponed, protracted, and becoming more complex (i.e., less likely to follow a predictable and “orderly” sequence as in earlier generations. Extended schooling periods, changes in the labor market and challenges to obtaining autonomous housing are some of the top drivers for such change. Demographers interpret such developments as a sign of a second demographic transition, whereas sociologists stress that they are a consequence of the broader process of social individualization, by which individuals are assuming an increasingly central role in the organization of their lives. While in younger cohorts the evidence base is strong concerning transitions to adulthood, in some national contexts comparisons with the past rely on impressionistic accounts or to easily assume that some social, economic, and cultural factors were present. Drawing on data from the “Family Trajectories and Social Networks: The life course in an intergenerational perspective” research project, this paper re-examines the transitions to adulthood of three Portuguese cohorts (born in 1935–1940, 1950–1955 and 1970–1975, namely in what concerns their timing, duration, and sequence. This is achieved by looking at their life-calendars across different domains (namely family and intimate relations, school, and work. Analysis of the results allows us to discuss critically to what extent current transitions to adulthood are different and to assess cohort heterogeneity according to class and gender. Additionally, it enables us to frame discussions on generational and structural change more adequately in Portugal.

Developing knowledge and strategies for enabling and governing transitions to a low carbon society

DEFF Research Database (Denmark)

Jørgensen, Michael Søgaard; Jørgensen, Ulrik; Lauridsen, Erik Hagelskjær

research alliance “Enabling and governing transitions to a low carbon society” during 2010-2013. The aim of this alliance is to conceptualize the dynamics of transition processes towards a low carbon society by involving the diverse set of actors from consumers to governmental agencies, companies...... and organizations. Transition of the path-dependent, socio-technical regimes in the energy system is a governance challenge, since transitions need to occur simultaneously in different arenas without necessarily having a specific „centre‟ of co-ordination. Changes of regimes require innovative breakthroughs......, companies, cities, and national and international policy. Theoretically the research alliance builds upon a combination of theories including social practice theory, innovation economy, institutional theory, actor-network theory and governance theory. Through a combination of historical analysis, case...

Density functional theory embedding for correlated wavefunctions: improved methods for open-shell systems and transition metal complexes.

Science.gov (United States)

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.

Glass transition in soft-sphere dispersions

International Nuclear Information System (INIS)

RamIrez-Gonzalez, P E; Medina-Noyola, M

2009-01-01

The concept of dynamic equivalence among mono-disperse soft-sphere fluids is employed in the framework of the self-consistent generalized Langevin equation (SCGLE) theory of colloid dynamics to calculate the ideal glass transition phase diagram of model soft-sphere colloidal dispersions in the softness-concentration state space. The slow dynamics predicted by this theory near the glass transition is compared with available experimental data for the decay of the intermediate scattering function of colloidal dispersions of soft-microgel particles. Increasing deviations from this simple scheme occur for increasingly softer potentials, and this is studied here using the Rogers-Young static structure factor of the soft-sphere systems as the input of the SCGLE theory, without assuming a priori the validity of the equivalence principle above.

EJSCREEN Demographic Indicators 2015 Public

Science.gov (United States)

EJSCREEN uses demographic factors as very general indicators of a community's potential susceptibility to the types of environmental factors included in this screening tool. There are six demographic indicators: Demographic Index, Supplementary Demographic Index, Individuals under Age 5, Individuals over Age 64, Percent Low-Income, Linguistic Isolation, Percent Minority, and Less than High School Education.

Outcomes of newly practicing nurses who applied principles of holistic comfort theory during the transition from school to practice: a qualitative study.

Science.gov (United States)

Goodwin, Miki; Candela, Lori

2013-06-01

The aim of this qualitative study was to explore if newly practicing nurses benefited from learning holistic comfort theory during their baccalaureate education, and to provide a conceptual framework to support the transition from school to practice. The study was conducted among graduates of an accelerated baccalaureate nursing program where holistic comfort theory was embedded as a learner-centered philosophy across the curriculum. A phenomenological process using van Manen's qualitative methodology in education involving semi-structured interviews and thematic analysis was used. The nurses recalled what holistic comfort meant to them in school, and described the lived experience of assimilating holistic comfort into their attitudes and behaviors in practice. Themes were established and a conceptual framework was developed to better understand the nurses' lived experiences. Results showed that holistic comfort was experienced as a constructive approach to transcend unavoidable difficulties during the transition from school to practice. Participants described meaningful learning and acquisition of self-strengthening behaviors using holistic comfort theory. Holistic comfort principles were credited for easing nurses into the realities of work and advocating for best patient outcomes. Patient safety and pride in patient care were incidental positive outcomes. The study offers new insights about applying holistic comfort to prepare nurses for the realities of practice. Copyright © 2012 Elsevier Ltd. All rights reserved.

Responsive survey design, demographic data collection, and models of demographic behavior.

Science.gov (United States)

Axinn, William G; Link, Cynthia F; Groves, Robert M

2011-08-01

To address declining response rates and rising data-collection costs, survey methodologists have devised new techniques for using process data ("paradata") to address nonresponse by altering the survey design dynamically during data collection. We investigate the substantive consequences of responsive survey design-tools that use paradata to improve the representative qualities of surveys and control costs. By improving representation of reluctant respondents, responsive design can change our understanding of the topic being studied. Using the National Survey of Family Growth Cycle 6, we illustrate how responsive survey design can shape both demographic estimates and models of demographic behaviors based on survey data. By juxtaposing measures from regular and responsive data collection phases, we document how special efforts to interview reluctant respondents may affect demographic estimates. Results demonstrate the potential of responsive survey design to change the quality of demographic research based on survey data.

Intrinsic irreversibility in quantum theory

International Nuclear Information System (INIS)

Prigogine, I.; Petrosky, T.Y.

1987-01-01

Quantum theory has a dual structure: while solutions of the Schroedinger equation evolve in a deterministic and time reversible way, measurement introduces irreversibility and stochasticity. This presents a contrast to Bohr-Sommerfeld-Einstein theory, in which transitions between quantum states are associated with spontaneous and induced transitions, defined in terms of stochastic processes. A new form of quantum theory is presented here, which contains an intrinsic form of irreversibility, independent of observation. This new form applies to situations corresponding to a continuous spectrum and to quantum states with finite life time. The usual non-commutative algebra associated to quantum theory is replaced by more general algebra, in which operators are also non-distributive. Our approach leads to a number of predictions, which hopefully may be verified or refuted in the next years. (orig.)

Problem-Solving Phase Transitions During Team Collaboration.

Science.gov (United States)

Wiltshire, Travis J; Butner, Jonathan E; Fiore, Stephen M

2018-01-01

Multiple theories of problem-solving hypothesize that there are distinct qualitative phases exhibited during effective problem-solving. However, limited research has attempted to identify when transitions between phases occur. We integrate theory on collaborative problem-solving (CPS) with dynamical systems theory suggesting that when a system is undergoing a phase transition it should exhibit a peak in entropy and that entropy levels should also relate to team performance. Communications from 40 teams that collaborated on a complex problem were coded for occurrence of problem-solving processes. We applied a sliding window entropy technique to each team's communications and specified criteria for (a) identifying data points that qualify as peaks and (b) determining which peaks were robust. We used multilevel modeling, and provide a qualitative example, to evaluate whether phases exhibit distinct distributions of communication processes. We also tested whether there was a relationship between entropy values at transition points and CPS performance. We found that a proportion of entropy peaks was robust and that the relative occurrence of communication codes varied significantly across phases. Peaks in entropy thus corresponded to qualitative shifts in teams' CPS communications, providing empirical evidence that teams exhibit phase transitions during CPS. Also, lower average levels of entropy at the phase transition points predicted better CPS performance. We specify future directions to improve understanding of phase transitions during CPS, and collaborative cognition, more broadly. Copyright © 2017 Cognitive Science Society, Inc.

Can Holstein-Kondo lattice model be used as a candidate for the theory of high transition temperature superconductors

Directory of Open Access Journals (Sweden)

R Nourafkan

2009-08-01

Full Text Available   It is a common knowledge that the formation of electron pairs is a necessary ingredient of any theoretical work describing superconductivity. Thus, finding the mechanism of the formation of the electron pairs is of utmost importance. There are some experiments on high transition temperature superconductors which support the electron-phonon (e-ph interactions as the pairing mechanism (ARPES, and there are others which support the spin fluctuations as their pairing mechanism (tunneling spectroscopy. In this paper, we introduce the Holstein-Kondo lattice model (H-KLM which incorporates the e-ph as well as the Kondo exchange interaction. We have used the dynamical mean field theory (DMFT to describe heavy fermion semiconductors and have employed the exact-diagonalization technique to obtain our results. The phase diagram of these systems in the parameter space of the e-ph coupling, g, and the Kondo exchange coupling, J, show that the system can be found in the Kondo insulating phase, metallic phase or the bi-polaronic phase. It is shown that these systems develop both spin gap and a charge gap, which are different and possess energies in the range of 1-100 meV. In view of the fact that both spin excitation energies and phonon energies lie in this range, we expect our work on H-KLM opens a way to formalize the theory of the high transition temperature superconductors .

The relationship between young people's transit use and their perceptions of equity concepts in transit service provision

DEFF Research Database (Denmark)

Kaplan, Sigal; de Abreu e Silva, João; Di Ciommo, Floridea

2014-01-01

This study investigates the effect of price and travel mode fairness and spatial equity in transit provision on the perceived transit service quality, willingness to pay, and habitual frequency of use. Based on the theory of planned behavior, we developed a web-based questionnaire for revealed...

Broadband luminescence in liquid-solid transition

CERN Document Server

Achilov, M F; Trunilina, O V

2002-01-01

Broadband luminescence (BBL) intensity behavior in liquid-solid transition in polyethyleneglycol-600 has been established. Oscillation of BBL intensity observed in liquid-polycrystal transition are not found to observed in liquid-amorphous solid transition. It is shown that application of the theory of electron state tails to interpretation of BBL spectral properties in liquids demands restriction. BBL spectroscopy may be applied for optimization of preparation of polymers with determined properties. (author)

Universal monopole scaling near transitions from the Coulomb phase.

Science.gov (United States)

Powell, Stephen

2012-08-10

Certain frustrated systems, including spin ice and dimer models, exhibit a Coulomb phase at low temperatures, with power-law correlations and fractionalized monopole excitations. Transitions out of this phase, at which the effective gauge theory becomes confining, provide examples of unconventional criticality. This Letter studies the behavior at nonzero monopole density near such transitions, using scaling theory to arrive at universal expressions for the crossover phenomena. For a particular transition in spin ice, quantitative predictions are made by mapping to the XY model and confirmed using Monte Carlo simulations.

An N=2 dual pair and a phase transition

International Nuclear Information System (INIS)

Aspinwall, P.S.

1996-01-01

We carefully analyze the N=2 dual pair of string theories in four dimensions introduced by Ferrara, Harvey, Strominger and Vafa. The analysis shows that a second discrete degree of freedom must be switched on in addition to the known ''Wilson line'' to achieve a non-perturbatively consistent theory. We also identify the phase transition this model undergoes into another dual pair via a process analogous to a conifold transition. This provides the first known example of a phase transition which is understood from both the type II and the heterotic string picture. (orig.)

Phase Transitions for Flat Anti - de Sitter Black Holes

International Nuclear Information System (INIS)

Surya, Sumati; Schleich, Kristin; Witt, Donald M.

2001-01-01

We reexamine the thermodynamics of anti - de Sitter (adS) black holes with Ricci flat horizons using the adS soliton as the thermal background. We find that there is a phase transition which is dependent not only on the temperature but also on the black hole area, which is an independent parameter. As in the spherical adS black hole, this phase transition is related via the adS/conformal-field-theory correspondence to a confinement-deconfinement transition in the large-N gauge theory on the conformal boundary at infinity

Analytical properties of a three-compartmental dynamical demographic model

Science.gov (United States)

Postnikov, E. B.

2015-07-01

The three-compartmental demographic model by Korotaeyv-Malkov-Khaltourina, connecting population size, economic surplus, and education level, is considered from the point of view of dynamical systems theory. It is shown that there exist two integrals of motion, which enables the system to be reduced to one nonlinear ordinary differential equation. The study of its structure provides analytical criteria for the dominance ranges of the dynamics of Malthus and Kremer. Additionally, the particular ranges of parameters enable the derived general ordinary differential equations to be reduced to the models of Gompertz and Thoularis-Wallace.

On an inversion procedure for nuclear transition densities

International Nuclear Information System (INIS)

Overveld, C.W.A.M. van.

1985-01-01

The aim of this thesis is to present a method by means of which experimental results can be analysed to establish transition densities of nuclear reactions. The necessity of such a method is explained together with the reaction theory involved. A chapter is devoted to the extension of a computer code for the scattering calculations in order to include the spin-orbit coupling. Detailed attention is paid to the mathematical and numerical properties of the method. The method is applied to some simple one-step reactions. The resulting transition densities are interpreted in terms of the shell model theory of nuclear structure. The final chapter deals with an entirely different approach to the extraction of transition densities from experimental data. Here the possibilities of the classical scattering theory as a method to solve the problem are studied. (Auth.)

Exact-exchange spin-density functional theory of Wigner localization and phase transitions in quantum rings.

Science.gov (United States)

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. © 2011 IOP Publishing Ltd

Dancing with Demographers.

Science.gov (United States)

Robertson, Heather-Jane

2000-01-01

Demographic projections concerning the shortage of teachers in Canada, their pay scale, the feminization of teaching, the gender gap in salaries, and teacher autonomy have often been incorrect, or correct for the wrong reasons. Instead of relying on demographic predictions, teachers should contemplate who they really want to be professionally,…

Theoretical investigation of pressure-induced structural transitions in americium using GGA+U and hybrid density functional theory methods

DEFF Research Database (Denmark)

Verma, Ashok K.; Modak, P.; Sharma, Surinder M.

2013-01-01

First-principles calculations have been performed for americium (Am) metal using the generalized gradient approximation + orbital-dependent onsite Coulomb repulsion via Hubbard interaction (GGA+U) and hybrid density functional theory (HYB-DFT) methods to investigate various ground state properties......-I to Am-II transition. Good agreement was found between calculated and experimental equations of states for all phases, but the first three phases need larger U (α) parameters (where α represents the fraction of Hartree-Fock exchange energy replacing the DFT exchange energy) than the fourth phase in order...

On a phase transition of a Kosterlitz-thouless-type in the d=4, U(1)-lattice gauge theory

International Nuclear Information System (INIS)

Marchetti, D.H.U.; Perez, J.F.

1986-12-01

The d=4, U(1)-lattice gauge theory with the Villain action may be represented as a locally neutral gas of topological (plaquette) charges which interact via a logarithmically confining potential, is shown. Using this representation a renormalization group analysis to show the existence of a phase transition of the Kosterlitz-Thouless-type was performed. An improved hierarchical version of the model which displays (unlike the usual Migdal-Kadanoff approach) a stable line of gaussian fixed points at low temperatures, which should correspond to the usual deconfining region of these systems is presented. (Author) [pt

Dos modelos de transición demográfica en América Latina

Directory of Open Access Journals (Sweden)

Ma. Eugenia Zavala de Cosío

1995-06-01

Full Text Available Demographic transition in Latin America began in 1930 with a decrease in mortality rates, followed in 1965 by a decrease in birth rates, parallel to an intense process of modernization in the subcontinent’s societies and economies. This model of demographic transition follows A. Landry’s classic theory, although it shows very different forms in the changes in marriage rates compared to European countries. In the 80’s a significant decrease in birth rates can be observed even in the poorer sectors and the most backward areas in Latin America. This process corresponds to a new one model of demographic transition. This process represents a new model of demographic transition, which could be considered as a "poverty Malthusianism", and can be applied to families who limit births, fearing the great deterioration of their living conditions.

Onset of dynamical chaos in topologically massive gauge theories

International Nuclear Information System (INIS)

Giansanti, A.; Simic, P.D.

1988-01-01

The onset of dynamical chaos is studied numerically in (2+1)-dimensional non-Abelian field theory with the Chern-Simons topological term. In the limit of strong fields, slowly varying in space (spatially homogeneous fields), this theory is an analog to a system of three charged particles moving in a plane in an orthogonal magnetic field and under the influence of a quartic potential. The ''phase transition'' (order chaos) is observed within a narrow energy range. The threshold of the transition depends on the sign of the angular momentum of the field reflecting parity violation in the underlying field theory. The transition region is investigated in some detail and the hyperfine structure of order-chaos-order-... transitions is observed suggesting the necessity of probabilistic description

Geometric transitions, flops and non-Kahler manifolds: I

International Nuclear Information System (INIS)

Becker, Melanie; Dasgupta, Keshav; Knauf, Anke; Tatar, Radu

2004-01-01

We construct a duality cycle which provides a complete supergravity description of geometric transitions in type II theories via a flop in M-theory. This cycle connects the different supergravity descriptions before and after the geometric transitions. Our construction reproduces many of the known phenomena studied earlier in the literature and allows us to describe some new and interesting aspects in a simple and elegant fashion. A precise supergravity description of new torsional manifolds that appear on the type IIA side with branes and fluxes and the corresponding geometric transition are obtained. A local description of new G2 manifolds that are circle fibrations over non-Kahler manifolds is presented

Crawford, Elisabeth: "Arrhenius: From Ionic Theory to the Greenhouse Effect" (Canton 1996); and Diana Barkan: "Walther Nernst and the Transition to Modern Physical Science" (Cambridge 1999) (book review)

OpenAIRE

Peter J. Ramberg

2000-01-01

book review of Crawford, Elisabeth: "Arrhenius: From Ionic Theory to the Greenhouse Effect" (Canton 1996); and Diana Barkan: "Walther Nernst and the Transition to Modern Physical Science" (Cambridge 1999)

Renormalization group theory of critical phenomena

International Nuclear Information System (INIS)

Menon, S.V.G.

1995-01-01

Renormalization group theory is a framework for describing those phenomena that involve a multitude of scales of variations of microscopic quantities. Systems in the vicinity of continuous phase transitions have spatial correlations at all length scales. The renormalization group theory and the pertinent background material are introduced and applied to some important problems in this monograph. The monograph begins with a historical survey of thermal phase transitions. The background material leading to the renormalization group theory is covered in the first three chapters. Then, the basic techniques of the theory are introduced and applied to magnetic critical phenomena in the next four chapters. The momentum space approach as well as the real space techniques are, thus, discussed in detail. Finally, brief outlines of applications of the theory to some of the related areas are presented in the last chapter. (author)

Metastability in Field Theory and Statistical Mechanics

International Nuclear Information System (INIS)

Carvalho, C.A. de.

1984-01-01

After a phase transition analysis which can occur in the framework of a scalar field theory, at finite temperature and in presence of a external field, possibles metastable situations are studied and also how is their relationship with the transitions. In both cases it is used a semiclassical approximation to the theory which, in Statistical Mechanics, corresponds to the droplet-bubble model. (L.C.) [pt

Crossover from equilibration to aging: Nonequilibrium theory versus simulations.

Science.gov (United States)

Mendoza-Méndez, P; Lázaro-Lázaro, E; Sánchez-Díaz, L E; Ramírez-González, P E; Pérez-Ángel, G; Medina-Noyola, M

2017-08-01

Understanding glasses and the glass transition requires comprehending the nature of the crossover from the ergodic (or equilibrium) regime, in which the stationary properties of the system have no history dependence, to the mysterious glass transition region, where the measured properties are nonstationary and depend on the protocol of preparation. In this work we use nonequilibrium molecular dynamics simulations to test the main features of the crossover predicted by the molecular version of the recently developed multicomponent nonequilibrium self-consistent generalized Langevin equation theory. According to this theory, the glass transition involves the abrupt passage from the ordinary pattern of full equilibration to the aging scenario characteristic of glass-forming liquids. The same theory explains that this abrupt transition will always be observed as a blurred crossover due to the unavoidable finiteness of the time window of any experimental observation. We find that within their finite waiting-time window, the simulations confirm the general trends predicted by the theory.

Statistical theory of L-H transition in tokamaks

International Nuclear Information System (INIS)

Itoh, S.-I.; Itoh, K.; Toda, S.

2003-01-01

A statistical model for the bifurcation of the radial electric field E r is developed in view of describing L-H transitions of tokamak plasmas. Noise in micro fluctuations is shown to lead to random changes of E r , if a deterministic approach allows for more than one solution. The probability density function for and the ensemble average of E 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 r , the limit deviates from Maxwell's rule. The ensemble average of heat flux as well as that of E r do not show a hysteresis in contrast to the deterministic model. Experimental condition for observing the hysteresis is also addressed. (author)

Branching ratios of radiative transitions in O VI

International Nuclear Information System (INIS)

Sur, Chiranjib; Chaudhuri, Rajat K

2007-01-01

We study the branching ratios of the allowed and forbidden radiative transitions among the first few (9) fine structure levels of O VI using relativistic coupled-cluster theory. We find irregular patterns for a number of transitions within n-complexes with n ≤ 4. We have used the existing values of the allowed electric dipole (E1) transition as a benchmark of our theory. Good agreement with the existing values establish accuracies of not only the theoretical method but the basis function as well. In general, the electric quadrupole (E2) transition probabilities are greater in magnitude than magnetic dipole (M1) transition probabilities, whereas for medium atomic transition frequencies they are of the same order of magnitude. On the other hand, if the transitions involved are in between two fine-structure components of the same term, then the M1 transition probability is more probable than that of E2. The results presented here in tabular and graphical form are compared with the available theoretical and observed data. Graphical analysis helps to understand the trends of electric and magnetic transitions for the decay channels presented here. Our calculated values of the lifetimes of the excited states are in very good agreement with the available results

The regional differentiation of the demographic movements in the Republic of Macedonia

Directory of Open Access Journals (Sweden)

Madjevikj Mirjanka

2016-09-01

Full Text Available The Republic of Macedonia covers an area of 25,713 km² and according to data from the census conducted in 2002, it has a population of 2,022,547 inhabitants. In the past, the Republic of Macedonia was characterized by some significant demographic changes, including a decline in the average annual rate of population increase. The enhanced immigration movements and sudden decline in the rates of natural population increase have led to changes in distribution of the population and to a spatial differentiation in the population. The long period of transition in the country has been reflected in the spatial development of the country and its demographic processes and to relocation of the population. The different natural-geographical characteristics, unequal regional development potentials, unequal economic development, and demographic characteristics have led to changes in the demographic situation of certain regions. The regions that continually lose part of its population clearly differ from these regions that are characterized by an increased population which is leading to a greater concentration of people in certain location. Further decades with a declining birth rate, followed by a change in the values of population increase, together with migration movements, particularly from the rural and less developed economic regions, has resulted in a decline in the population. The different zones of depopulation and concentration in a simple way express the complex relationships in the population composition.

Density-functional theory study of the pressure-induced phase transition in hydronitrogen compound N{sub 4}H{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Liu, Qi-Jun, E-mail: qijunliu@home.swjtu.edu.cn [Bond and Band Engineering Group, Sichuan Provincial Key Laboratory (for Universities) of High Pressure Science and Technology, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhang, Ning-Chao; Sun, Yan-Yun; Zhang, Ming-Jian; Liu, Fu-Sheng [Bond and Band Engineering Group, Sichuan Provincial Key Laboratory (for Universities) of High Pressure Science and Technology, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Liu, Zheng-Tang [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi' an, Shaanxi 710072 (China)

2014-03-01

Using first-principles density-functional theory, we have investigated the pressure-induced phase transition in hydronitrogen compound N{sub 4}H{sub 4} and discussed the potential tetragonal structure. We find that tetragonal structure with P4{sub 2}/n space group is mechanically stable and ductile. The thermodynamic stability of Pmna>P1{sup ¯}>P4{sub 2}/n>P2{sub 1}/m has been obtained. With increasing pressure, the phase transition pressures of T{sub Pmna→P4{sub 2/n}}, T{sub P4{sub 2/n→Pmna}}, T{sub Pmna→P1{sup ¯}} and T{sub P1{sup ¯}→P2{sub 1/m}} are 5.6, 15.0, 30.0 and 69.2 GPa, respectively, which are in agreement with the available data. Moreover, the mechanical stability of four structures under pressure has been analyzed.

Smoothed transitions in higher spin AdS gravity

International Nuclear Information System (INIS)

Banerjee, Shamik; Shenker, Stephen; Castro, Alejandra; Hellerman, Simeon; Hijano, Eliot; Lepage-Jutier, Arnaud; Maloney, Alexander

2013-01-01

We consider CFTs conjectured to be dual to higher spin theories of gravity in AdS 3 and AdS 4 . Two-dimensional CFTs with W N symmetry are considered in the λ = 0 (k → ∞) limit where they are conjectured to be described by continuous orbifolds. The torus partition function is computed, using reasonable assumptions, and equals that of a free-field theory. We find no phase transition at temperatures of order 1; the usual Hawking–Page phase transition is removed by the highly degenerate light states associated with conical defect states in the bulk. Three-dimensional Chern–Simons matter CFTs with vector-like matter are considered on T 3 , where the dynamics is described by an effective theory for the eigenvalues of the holonomies. Likewise, we find no evidence for a Hawking–Page phase transition at a large level k. (paper)

Branes and Six Dimensional Supersymmetric Theories

CERN Document Server

Hanany, Amihay; Hanany, Amihay; Zaffaroni, Alberto

1998-01-01

We consider configurations of sixbranes, fivebranes and eightbranes in various superstring backgrounds. These configurations give rise to $(0,1)$ supersymmetric theories in six dimensions. The condition for RR charge conservation of a brane configuration translates to the condition that the corresponding field theory is anomaly free. Sets of infinitely many models with non trivial RG fixed points at strong coupling are demonstrated. Some of them reproduce and generalise the world-volume theories of SO(32) and $E_8\\times E_8$ small instantons. All the models are shown to be connected by smooth transitions. In particular, the small instanton transition for which a tensor multiplet is traded for 29 hypermultiplets is explicitly demonstrated. The particular limit in which these theories can be considered as six dimensional string theories without gravity are discussed. New fixed points (string theories) associated with $E_n$ global symmetries are discovered by taking the strong string coupling limit.

Fertility transition: forecast for demography.

Science.gov (United States)

Caputo, M; Nicotra, M; Gloria-Bottini, E

2008-08-01

By the end of the 20th century most industrialized nations had undergone the so-called fertility transition, characterized by a reduction in fertility to below replacement level and a delay in age at initiation of child-bearing. An emerging concern is the severe economic and social consequences of this demographic decline. We present an overview of fertility changes in Italy in the second half of the 20th century and a mathematical model that may provide projections for the future of the demographic situation. Starting in 1950 the increment of the number of children born in Italy is initially positive; however, beginning in 1965 the trend suddenly becomes negative, and this negative trend further increased in 1975. A slight improvement is observed in 1980, followed by a stable situation beginning in 1987. Relevant socioeconomic and cultural events in Italy coincide with these variations in the fertility trend. Malnutrition, which had been endemic for centuries in some areas of central and southern Italy, disappeared rather abruptly in early 1960. The improvement in the economic situation was also associated with a decrease in illiteracy and with many sociocultural changes, with the emergence of new demands that decreased propensity for childbearing. The additional deceleration observed in 1975 corresponds to the diffusion of contraceptive procedures. The progression of sociocultural changes has led to a progressive liberation of women from the biological burden of childbearing. Two phenomena seem relevant in this context: women's emerging interest in entering the workforce and the possibility to disconnect sex from childbearing. The social function of feminism has overwhelmed the primary function of survival and diffusion of the species, giving rise to relevant and worrying demographic effects. However, the modern woman has an unconscious memory of her primary biological role, depending on both her genetic structure and cultural heritage, that should bring about a

Decision analysis with cumulative prospect theory.

Science.gov (United States)

Bayoumi, A M; Redelmeier, D A

2000-01-01

Individuals sometimes express preferences that do not follow expected utility theory. Cumulative prospect theory adjusts for some phenomena by using decision weights rather than probabilities when analyzing a decision tree. The authors examined how probability transformations from cumulative prospect theory might alter a decision analysis of a prophylactic therapy in AIDS, eliciting utilities from patients with HIV infection (n = 75) and calculating expected outcomes using an established Markov model. They next focused on transformations of three sets of probabilities: 1) the probabilities used in calculating standard-gamble utility scores; 2) the probabilities of being in discrete Markov states; 3) the probabilities of transitioning between Markov states. The same prophylaxis strategy yielded the highest quality-adjusted survival under all transformations. For the average patient, prophylaxis appeared relatively less advantageous when standard-gamble utilities were transformed. Prophylaxis appeared relatively more advantageous when state probabilities were transformed and relatively less advantageous when transition probabilities were transformed. Transforming standard-gamble and transition probabilities simultaneously decreased the gain from prophylaxis by almost half. Sensitivity analysis indicated that even near-linear probability weighting transformations could substantially alter quality-adjusted survival estimates. The magnitude of benefit estimated in a decision-analytic model can change significantly after using cumulative prospect theory. Incorporating cumulative prospect theory into decision analysis can provide a form of sensitivity analysis and may help describe when people deviate from expected utility theory.

Correspondence between quantum gauge theories without ghost fields and their covariantly quantized theories with ghost fields

International Nuclear Information System (INIS)

Cheng Hung; Tsai Ercheng

1986-01-01

We give a correspondence formula which equates transition amplitudes in a quantum gauge field theory without ghost fields to those in a quantum theory with the gauge fields covariantly quantized and coupled to ghost fields. (orig.)

Theory of high-T{sub C} superconductivity: transition temperature

Energy Technology Data Exchange (ETDEWEB)

Harshman, Dale R [Physikon Research Corporation, Lynden, WA 98264 (United States); Fiory, Anthony T [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Dow, John D, E-mail: drh@physikon.net [Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

2011-07-27

It is demonstrated that the transition temperature (T{sub C}) of high-T{sub C} superconductors is determined by their layered crystal structure, bond lengths, valency properties of the ions, and Coulomb coupling between electronic bands in adjacent, spatially separated layers. Analysis of 31 high-T{sub C} materials (cuprates, ruthenates, ruthenocuprates, iron pnictides, organics) yields the universal relationship for optimal compounds, k{sub B}T{sub C0} ={beta}/{iota}{zeta}, where {iota} is related to the mean spacing between interacting charges in the layers, {zeta} is the distance between interacting electronic layers, {beta} is a universal constant and T{sub C0} is the optimal transition temperature (determined to within an uncertainty of {+-} 1.4 K by this relationship). Non-optimum compounds, in which sample degradation is evident, e.g. by broadened superconducting transitions and diminished Meissner fractions, typically exhibit reduced T{sub C} < T{sub C0}. It is shown that T{sub C0} may be obtained from an average of the Coulomb interaction forces between the two layers.

Application of an excited state LDA exchange energy functional for the calculation of transition energy of atoms within time-independent density functional theory

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.

Application of an excited state LDA exchange energy functional for the calculation of transition energy of atoms within time-independent density functional theory

International Nuclear Information System (INIS)

Shamim, Md; Harbola, Manoj K

2010-01-01

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.

Statistical theory of L-H transition in tokamaks

Energy Technology Data Exchange (ETDEWEB)

Itoh, S.-I. [Kyushu Univ., Research Institute for Applied Mechanics, Kasuga, Fukuoka (Japan); Itoh, K.; Toda, S. [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 developed in view of describing L-H transitions of tokamak 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. The ensemble average of heat flux as well as that of E{sub r} do not show a hysteresis in contrast to the deterministic model. Experimental condition for observing the hysteresis is also addressed. (author)

Relation Between Higher Physical Activity and Public Transit Use

Science.gov (United States)

Vernez Moudon, Anne; Kang, Bumjoon; Hurvitz, Philip M.; Zhou, Chuan

2014-01-01

Objectives. We isolated physical activity attributable to transit use to examine issues of substitution between types of physical activity and potential confounding of transit-related walking with other walking. Methods. Physical activity and transit use data were collected in 2008 to 2009 from 693 Travel Assessment and Community study participants from King County, Washington, equipped with an accelerometer, a portable Global Positioning System, and a 7-day travel log. Physical activity was classified into transit- and non–transit-related walking and nonwalking time. Analyses compared physical activity by type between transit users and nonusers, between less and more frequent transit users, and between transit and nontransit days for transit users. Results. Transit users had more daily overall physical activity and more total walking than did nontransit users but did not differ on either non–transit-related walking or nonwalking physical activity. Most frequent transit users had more walking time than least frequent transit users. Higher physical activity levels for transit users were observed only on transit days, with 14.6 minutes (12.4 minutes when adjusted for demographics) of daily physical activity directly linked with transit use. Conclusions. Because transit use was directly related to higher physical activity, future research should examine whether substantive increases in transit access and use lead to more physical activity and related health improvements. PMID:24625142

Phase transitions in single macromolecules: Loop-stretch transition versus loop adsorption transition in end-grafted polymer chains

Science.gov (United States)

Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I.; Skvortsov, Alexander M.; Yan, Dadong; Schmid, Friederike

2018-01-01

We use Brownian dynamics simulations and analytical theory to compare two prominent types of single molecule transitions. One is the adsorption transition of a loop (a chain with two ends bound to an attractive substrate) driven by an attraction parameter ɛ and the other is the loop-stretch transition in a chain with one end attached to a repulsive substrate, driven by an external end-force F applied to the free end. Specifically, we compare the behavior of the respective order parameters of the transitions, i.e., the mean number of surface contacts in the case of the adsorption transition and the mean position of the chain end in the case of the loop-stretch transition. Close to the transition points, both the static behavior and the dynamic behavior of chains with different length N are very well described by a scaling ansatz with the scaling parameters (ɛ - ɛ*)Nϕ (adsorption transition) and (F - F*)Nν (loop-stretch transition), respectively, where ϕ is the crossover exponent of the adsorption transition and ν is the Flory exponent. We show that both the loop-stretch and the loop adsorption transitions provide an exceptional opportunity to construct explicit analytical expressions for the crossover functions which perfectly describe all simulation results on static properties in the finite-size scaling regime. Explicit crossover functions are based on the ansatz for the analytical form of the order parameter distributions at the respective transition points. In contrast to the close similarity in equilibrium static behavior, the dynamic relaxation at the two transitions shows qualitative differences, especially in the strongly ordered regimes. This is attributed to the fact that the surface contact dynamics in a strongly adsorbed chain is governed by local processes, whereas the end height relaxation of a strongly stretched chain involves the full spectrum of Rouse modes.

Infrared finiteness in Yang--Mills theories

International Nuclear Information System (INIS)

Appelquist, T.; Carazzone, J.; Kluberg-Stern, H.; Roth, M.

1976-01-01

The infrared divergences of renormalizable theories with coupled massless fields (in particular, the Yang--Mills theory) are shown to cancel for transition probabilities corresponding to finite-energy-resolution detectors, just as in quantum electrodynamics. This result is established through lowest nontrivial order in perturbation theory for the detection of massive muons in a quantum electrodynamic theory containing massless electrons or the detection of massive quarks in a Yang--Mills theory

Life history tactics shape amphibians' demographic responses to the North Atlantic Oscillation.

Science.gov (United States)

Cayuela, Hugo; Joly, Pierre; Schmidt, Benedikt R; Pichenot, Julian; Bonnaire, Eric; Priol, Pauline; Peyronel, Olivier; Laville, Mathias; Besnard, Aurélien

2017-11-01

Over the last three decades, climate abnormalities have been reported to be involved in biodiversity decline by affecting population dynamics. A growing number of studies have shown that the North Atlantic Oscillation (NAO) influences the demographic parameters of a wide range of plant and animal taxa in different ways. Life history theory could help to understand these different demographic responses to the NAO. Indeed, theory states that the impact of weather variation on a species' demographic traits should depend on its position along the fast-slow continuum. In particular, it is expected that NAO would have a higher impact on recruitment than on adult survival in slow species, while the opposite pattern is expected occur in fast species. To test these predictions, we used long-term capture-recapture datasets (more than 15,000 individuals marked from 1965 to 2015) on different surveyed populations of three amphibian species in Western Europe: Triturus cristatus, Bombina variegata, and Salamandra salamandra. Despite substantial intraspecific variation, our study revealed that these three species differ in their position on a slow-fast gradient of pace of life. Our results also suggest that the differences in life history tactics influence amphibian responses to NAO fluctuations: Adult survival was most affected by the NAO in the species with the fastest pace of life (T. cristatus), whereas recruitment was most impacted in species with a slower pace of life (B. variegata and S. salamandra). In the context of climate change, our findings suggest that the capacity of organisms to deal with future changes in NAO values could be closely linked to their position on the fast-slow continuum. © 2017 John Wiley & Sons Ltd.

Quantum phase transitions

International Nuclear Information System (INIS)

Sachdev, S.

1999-01-01

Phase transitions are normally associated with changes of temperature but a new type of transition - caused by quantum fluctuations near absolute zero - is possible, and can tell us more about the properties of a wide range of systems in condensed-matter physics. Nature abounds with phase transitions. The boiling and freezing of water are everyday examples of phase transitions, as are more exotic processes such as superconductivity and superfluidity. The universe itself is thought to have passed through several phase transitions as the high-temperature plasma formed by the big bang cooled to form the world as we know it today. Phase transitions are traditionally classified as first or second order. In first-order transitions the two phases co-exist at the transition temperature - e.g. ice and water at 0 deg., or water and steam at 100 deg. In second-order transitions the two phases do not co-exist. In the last decade, attention has focused on phase transitions that are qualitatively different from the examples noted above: these are quantum phase transitions and they occur only at the absolute zero of temperature. The transition takes place at the ''quantum critical'' value of some other parameter such as pressure, composition or magnetic field strength. A quantum phase transition takes place when co-operative ordering of the system disappears, but this loss of order is driven solely by the quantum fluctuations demanded by Heisenberg's uncertainty principle. The physical properties of these quantum fluctuations are quite distinct from those of the thermal fluctuations responsible for traditional, finite-temperature phase transitions. In particular, the quantum system is described by a complex-valued wavefunction, and the dynamics of its phase near the quantum critical point requires novel theories that have no analogue in the traditional framework of phase transitions. In this article the author describes the history of quantum phase transitions. (UK)

Gravitation and source theory

International Nuclear Information System (INIS)

Yilmaz, H.

1975-01-01

Schwinger's source theory is applied to the problem of gravitation and its quantization. It is shown that within the framework of a flat-space the source theory implementation leads to a violation of probability. To avoid the difficulty one must introduce a curved space-time hence the source concept may be said to necessitate the transition to a curved-space theory of gravitation. It is further shown that the curved-space theory of gravitation implied by the source theory is not equivalent to the conventional Einstein theory. The source concept leads to a different theory where the gravitational field has a stress-energy tensor t/sup nu//sub mu/ which contributes to geometric curvatures

Privatization in economic theory

Directory of Open Access Journals (Sweden)

Drakić Maja

2007-01-01

Full Text Available In reality privatization has never occurred according to the handbook rules of ordinary market transactions. Not even in advanced market economies can privatization transactions be described by the Walrasian or Arrowian, or Leontiefian equilibrium models, or by the equilibrium models of the game theory. In these economies transactions of privatization take place in a fairly organic way – which means that those are driven by the dominance of private property rights and in a market economy. But despite this fact Western privatization also some peculiar features as compared to ordinary company takeovers, since the state as the seller may pursue non – economic goals. Changes in the dominant form of property change positions and status of many individuals and groups in the society. That’s why privatization can even less be explained by ordinary market mechanisms in transition countries where privatizing state-owned property have happened in a mass scale and where markets and private property rights weren't established at the time process of privatization began. In this paper I’ll discuss and analyze the phenomenon of privatization in context of different economic theories arguing that empirical results go in favor of the public choice theory (Buchanan, 1978, theory of "economic constitution" (Brennan and Buchanan 1985, (Buchanan and Tullock, 1989, and theory of "collective action" (Olson, 1982. These theories argues that transition from one economic system into another, for example transition from collectivistic, socialistic system into capitalism and free market economy with dominant private property, will not happen through isolated changes of only few economic institutions, no matter how deep that changes would be. In other words privatization can not give results if it's not followed by comprehensive change of economic system because privatized companied wouldn't be able to operate in old environment.

Quantum transitions through cosmological singularities

Energy Technology Data Exchange (ETDEWEB)

Bramberger, Sebastian F.; Lehners, Jean-Luc [Max Planck Institute for Gravitational Physics (Albert Einstein Institute), 14476 Potsdam-Golm (Germany); Hertog, Thomas; Vreys, Yannick, E-mail: sebastian.bramberger@aei.mpg.de, E-mail: thomas.hertog@kuleuven.be, E-mail: jlehners@aei.mpg.de, E-mail: yannick.vreys@kuleuven.be [Institute for Theoretical Physics, KU Leuven, 3001 Leuven (Belgium)

2017-07-01

In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.

Quantum transitions through cosmological singularities

International Nuclear Information System (INIS)

Bramberger, Sebastian F.; Lehners, Jean-Luc; Hertog, Thomas; Vreys, Yannick

2017-01-01

In a quantum theory of cosmology spacetime behaves classically only in limited patches of the configuration space on which the wave function of the universe is defined. Quantum transitions can connect classical evolution in different patches. Working in the saddle point approximation and in minisuperspace we compute quantum transitions connecting inflationary histories across a de Sitter like throat or a singularity. This supplies probabilities for how an inflating universe, when evolved backwards, transitions and branches into an ensemble of histories on the opposite side of a quantum bounce. Generalising our analysis to scalar potentials with negative regions we identify saddle points describing a quantum transition between a classically contracting, crunching ekpyrotic phase and an inflationary universe.

Lattice simulations of QCD-like theories at finite baryon density

Energy Technology Data Exchange (ETDEWEB)

Scior, Philipp Friedrich

2016-07-13

The exploration of the phase diagram of quantum chromodynamics (QCD) is of great importance to describe e.g. the properties of neutron stars or heavy-ion collisions. Due to the sign problem of lattice QCD at finite chemical potential we need effective theories to study QCD at finite density. Here, we use a three-dimensional Polyakov-loop theory to study the phase diagrams of QCD-like theories. In particular, we investigate the heavy quark limit of the QCD-like theories where the effective theory can be derived from the full theory by a combined strong coupling and hopping expansion. This expansion can be systematically improved order by order. Since there is no sign problem for the QCD-like theories we consider, we can compare our results to data from lattice calculations of the full theories to make qualitative and quantitative statements of the effective theory's validity. We start by deriving the effective theory up to next-to-next-to leading-order, in particular for two-color and G{sub 2}-QCD where replace the three colors in QCD with only two colors or respectively replace the gauge group SU(3) of QCD with G{sub 2}. We will then apply the effective theory at finite temperature mainly to test the theory and the implementation but also to make some predictions for the deconfinement phase transition in G{sub 2} Yang-Mills theory. Finally, we turn our attention to the cold and dense regime of the phase diagram where we observe a sharp increase of the baryon density with the quark chemical potential μ, when μ reaches half the diquark mass. At vanishing temperature this is expected to happen in a quantum phase transition with Bose-Einstein-condensation of diquarks. In contrast to the liquid-gas transition in QCD, the phase transition to the Bose-Einstein condensate is continuous. We find evidence that the effective theories for heavy quarks are able to describe the qualitative difference between first and second order phase transitions. For even higher μ we

Lattice simulations of QCD-like theories at finite baryon density

International Nuclear Information System (INIS)

Scior, Philipp Friedrich

2016-01-01

The exploration of the phase diagram of quantum chromodynamics (QCD) is of great importance to describe e.g. the properties of neutron stars or heavy-ion collisions. Due to the sign problem of lattice QCD at finite chemical potential we need effective theories to study QCD at finite density. Here, we use a three-dimensional Polyakov-loop theory to study the phase diagrams of QCD-like theories. In particular, we investigate the heavy quark limit of the QCD-like theories where the effective theory can be derived from the full theory by a combined strong coupling and hopping expansion. This expansion can be systematically improved order by order. Since there is no sign problem for the QCD-like theories we consider, we can compare our results to data from lattice calculations of the full theories to make qualitative and quantitative statements of the effective theory's validity. We start by deriving the effective theory up to next-to-next-to leading-order, in particular for two-color and G_2-QCD where replace the three colors in QCD with only two colors or respectively replace the gauge group SU(3) of QCD with G_2. We will then apply the effective theory at finite temperature mainly to test the theory and the implementation but also to make some predictions for the deconfinement phase transition in G_2 Yang-Mills theory. Finally, we turn our attention to the cold and dense regime of the phase diagram where we observe a sharp increase of the baryon density with the quark chemical potential μ, when μ reaches half the diquark mass. At vanishing temperature this is expected to happen in a quantum phase transition with Bose-Einstein-condensation of diquarks. In contrast to the liquid-gas transition in QCD, the phase transition to the Bose-Einstein condensate is continuous. We find evidence that the effective theories for heavy quarks are able to describe the qualitative difference between first and second order phase transitions. For even higher μ we find the rise of the

Landau-de Gennes theory of surface-enhanced ordering in smectic films.

Science.gov (United States)

Shalaginov, A N; Sullivan, D E

2001-03-01

A Landau theory for surface-enhanced ordering in smectic-A free-standing films is described, based on a generalization of de Gennes' model for a "presmectic" fluid confined between two walls. According to the theory, smectic ordering in free-standing films heated above the bulk smectic melting temperature is due to an intrinsic surface contribution rather than an external field. The theory yields a persistent finite-size effect, in that the film melting temperatures do not tend to the bulk transition temperature in the limit of infinite film thickness. It also predicts that a continuous transition from (N+1)- to N-layer films is impossible without an external field. The theory closely fits existing experimental data on layer-thinning transitions in compounds which exhibit a bulk smectic-A to nematic phase transition. Possible origins of the intrinsic surface contribution are discussed.

A grain boundary phase transition in Si–Au

International Nuclear Information System (INIS)

Ma, Shuailei; Meshinchi Asl, Kaveh; Tansarawiput, Chookiat; Cantwell, Patrick R.; Qi, Minghao; Harmer, Martin P.; Luo, Jian

2012-01-01

A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si–Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition.

Transition scattering in electrodynamics and general relativity theory

Energy Technology Data Exchange (ETDEWEB)

Ginzburg, V L; Tsytovich, V N [AN SSSR, Moscow. Fizicheskij Inst.

1975-01-01

The question of transition scattering is discussed, i.e., the production of an electromagnetic wave when a permittivity wave or a gravitational wave fall upon the region with a static electromagnetic field (the field of charge, of an electric or magnetic dipole, and so on).

The transition of childbirth practices among tribal women in Gujarat, India - a grounded theory approach

Science.gov (United States)

2013-01-01

Background 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. Method 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. Results 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. Conclusion In resource poor settings where choices are

In the realm of the geometric transitions

International Nuclear Information System (INIS)

Alexander, Stephon; Becker, Katrin; Becker, Melanie; Dasgupta, Keshav; Knauf, Anke; Tatar, Radu

2005-01-01

We complete the duality cycle by constructing the geometric transition duals in the type IIB, type I and heterotic theories. We show that in the type IIB theory the background on the closed string side is a Kaehler deformed conifold, as expected, even though the mirror type IIA backgrounds are non-Kaehler (both before and after the transition). On the other hand, the type I and heterotic backgrounds are non-Kaehler. Therefore, on the heterotic side these backgrounds give rise to new torsional manifolds that have not been studied before. We show the consistency of these backgrounds by verifying the torsional equation

Using demographic data to better interpret pitfall trap catches

Directory of Open Access Journals (Sweden)

Andrey Matalin

2011-05-01

Full Text Available The results of pitfall trapping are often interpreted as abundance in a particular habitat. At the same time, there are numerous cases of almost unrealistically high catches of ground beetles in seemingly unsuitable sites. The correlation of catches by pitfall trapping with the true distribution and abundance of Carabidae needs corroboration. During a full year survey in 2006/07 in the Lake Elton region (Volgograd Area, Russia, 175 species of ground beetles were trapped. Considering the differences in demographic structure of the local populations, and not their abundances, three groups of species were recognized: residents, migrants and sporadic. In residents, the demographic structure of local populations is complete, and their habitats can be considered “residential”. In migrants and sporadic species, the demographic structure of the local populations is incomplete, and their habitats can be considered “transit”. Residents interact both with their prey and with each other in a particular habitat. Sporadic species are hardly important to a carabid community because of their low abundances. The contribution of migrants to the structure of carabid communities is not apparent and requires additional research. Migrants and sporadic species represent a “labile” component in ground beetles communities, as opposed to a “stable” component, represented by residents. The variability of the labile component substantially limits our interpretation of species diversity in carabid communities. Thus, the criteria for determining the most abundant, or dominant species inevitably vary because the abundance of migrants in some cases can be one order of magnitude higher than that of residents. The results of pitfall trapping adequately reflect the state of carabid communities only in zonal habitats, while azonal and disturbed habitats are merely transit ones for many species of ground beetles. A study of the demographic structure of local

Policy Implications of the Variations in Ghana's Fertility Transition ...

African Journals Online (AJOL)

The results of three consecutive Demographic and Health Surveys (GDHS), carried out in 1986, 1993, 1998, show that Ghana's population has been experiencing a fertility transition. An analysis of the data, however, indicates that there are wide and increasing differentials in both the timing and trends in the process among ...

The Theory of Dynamic Public Transit Priority with Dynamic Stochastic Park and Ride

OpenAIRE

Zhu, Chengming; Chen, Yanyan; Ma, Changxi

2014-01-01

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, scal...

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.

Non-equilibrium phase transitions

CERN Document Server

Henkel, Malte; Lübeck, Sven

2009-01-01

This book describes two main classes of non-equilibrium phase-transitions: (a) static and dynamics of transitions into an absorbing state, and (b) dynamical scaling in far-from-equilibrium relaxation behaviour and ageing. The first volume begins with an introductory chapter which recalls the main concepts of phase-transitions, set for the convenience of the reader in an equilibrium context. The extension to non-equilibrium systems is made by using directed percolation as the main paradigm of absorbing phase transitions and in view of the richness of the known results an entire chapter is devoted to it, including a discussion of recent experimental results. Scaling theories and a large set of both numerical and analytical methods for the study of non-equilibrium phase transitions are thoroughly discussed. The techniques used for directed percolation are then extended to other universality classes and many important results on model parameters are provided for easy reference.

Demographic Transformation in a Policy Vacuum: The Changing Face of U.S. Metropolitan Society and Challenges for Public Schools

Science.gov (United States)

Mordechay, Kfir; Orfield, Gary

2017-01-01

Educators and policy makers must confront the race and class disparities in learning opportunities across American society. Nowhere are these disparities more acute than in the country's great metropolitan areas. As the demographic landscape continues to shift, metropolitan areas are fueling the transition to a majority-minority country. This…

Phase transition of the FCC Ising ferromagnet with competing interactions

International Nuclear Information System (INIS)

Oh, J.H.; Lee, J.Y.; Kim, D.C.

1984-01-01

A molecular field theory with correlation and Monte Carlo simulations are utilized to determine the zero field phase diagram of a fcc Ising model with ferromagnetic nearest neighbor(-J) and antiferromagnetic next neighbor (*aJ) interactions. The correlated molecular field theory predicts a fluctuation induced first order phase transition for 0.87<*a<1.31. Monte Carlo analysis indicates that the first order transition occurs for a somewhat wider range of *a. The transition temperatures obtained by the two methods are in good agreement especially near *a=1 where the fluctuation effect is expected to be large. (Author)

Theory of fast (nonadiabatic) nuclear rotation

International Nuclear Information System (INIS)

Nosov, V.G.; Kamchatnov, A.M.

1977-01-01

The theory of backbending is developed taking into accout the increasing role of nonadiabatic effects, which are concerned with quantum number K violation. Above the transition point, rotation quantum number j (>=) jsub(c) (second-kind transition point), all possible values of the quantity K in the interval -J ( Jsub(c) are obtained. The radius of global nucleon mass distribution in the nucleus is defined from the analysis of the experimental moments of inertia in n-phase. It is in agreement with the radius of distribution of protons alone obtained from electron scattering on nuclei. Assuming the simplest singularity of parametric derivative of the Hamiltonian of the system the general theory of non-temperature (ground state)second-kind phase transitions is developed

The people yet to come; avoiding the demographic trap.

Science.gov (United States)

Brown, L R

1987-01-01

The demographic trap is defined as the condition where a nation has passed through the process of lowering death rates, but has not been able to lower birth rates before ecological carrying capacity is exceeded. A minimal estimate predicts that by the year 2000, 63 countries, or 1.1 billion people, will be trapped by starvation, dependence on imported food, and resulting economic and political instability. Such a country that failed to complete the demographic transition will fall back to the original stage, of high death as well as birth rates. Most nations in Southeast Asia, Latin America, and Africa are at risk, notably Mexico, India, Nigeria, Ethiopia, because they already have falling living standards coupled with rapid growth rates. Most governments are unaware of the subtle signs that carrying capacity has been exceeded. Even those that are able to understand such events, often practice ineffective policies. For example, the U.S. has dropped U.N.F.P.A. support ostensibly because one nation, China, allowed forced abortions. On the other hand, some third world countries have initiated novel campaigns to reduce births, for example popular media campaigns in Mexico, free dissemination of birth control pills to all women in Brazil, and a separate family planning ministry in Zimbabwe.

Towards the Theory of monetary degradation, or Post Keynesian analysis of monetary problems of the Russian transitional economy in 1991-1998

OpenAIRE

ROZMAINSKY I.V.

2016-01-01

The paper develops Post Keynesian theory of endogenous money and applies it to analysis of changes in monetary circulation in the Russian transitional economy in 1991-1998. These changes were characterized by displacement of bank deposits by cash, barter and inter-firm arrears as special means of payment. Author treats this process as «monetary degradation» because it created additional barriers to financing investment, made for criminalization and contributed to cost-push inflation. All this...

Population dynamics along a primary succession gradient: do alpine species fit into demographic succession theory?

Science.gov (United States)

Marcante, Silvia; Winkler, Eckart; Erschbamer, Brigitta

2009-05-01

Understanding processes and mechanisms governing changes in plant species along primary successions has been of major importance in ecology. However, to date hardly any studies have focused on the complete life cycle of species along a successional gradient, comparing pioneer, early and late-successional species. In this study it is hypothesized that pioneer species should initially have a population growth rate, lambda, greater than one with high fecundity rates, and declining growth rates when they are replaced by late-successional species. Populations of late-successional species should also start, at the mid-successional stage (when pioneer species are declining), with growth rates greater than one and arrive at rates equal to one at the late successional stage, mainly due to higher survival rates that allow these species to persist for a long time. The demography of pioneer- (Saxifraga aizoides), early (Artemisia genipi) and late-successional species (Anthyllis vulneraria ssp. alpicola) was investigated together with that of a ubiquitous species (Poa alpina) along the Rotmoos glacier foreland (2300-2400 m a.s.l., Central Alps, Austria) over 3 years. A matrix modelling approach was used to compare the main demographic parameters. Elasticity values were plotted in a demographic triangle using fecundity, individual growth and survival as vital rates contributing to the population growth rates. The results largely confirmed the predictions for population growth rates during succession. However, high survival rates of larger adults characterized all species, regardless of where they were growing along the succession. At the pioneer site, high mortality rates of seedlings, plantlets and young individuals were recorded. Fecundity was found to be of minor relevance everywhere, but it was nevertheless sufficient to increase or maintain the population sizes. Demographically, all the species over all sites behaved like late-successional or climax species in secondary

Particle identification via transition radiation and detectors

International Nuclear Information System (INIS)

Egorytchev, V.; Saveliev, V.; Aplin, S.J.

2000-01-01

Transition radiation detectors show great promise for the purposes of lepton identification in existing and future experiments in high-energy physics such as HERA-B, ATLAS, ALICE in high-luminosity environment. More high performance can be expected in low-luminosity conditions - neutrino experiments (NOMAD), and ideal condition for the use of transition radiation detectors in flying and space high-energy experiments (AMS). This paper discusses the practical theory of transition radiation, basic equation and algorithm suitable for detailed analysis of transition radiation and optimization of transition radiation detectors in the area of experimental high-energy physics. The results are based on detailed Monte Carlo simulation of transition radiation introduced in GEANT and experimental results

Particle identification via transition radiation and detectors

CERN Document Server

Egorytchev, V; Aplin, S J

2000-01-01

Transition radiation detectors show great promise for the purposes of lepton identification in existing and future experiments in high- energy physics such as HERA-B, ATLAS, ALICE in high-luminosity environment. More high performance can be expected in low-luminosity conditions-neutrino experiments (NOMAD), and the ideal condition for the use of transition radiation detectors in flying and space high- energy experiments (AMS). This paper discusses the practical theory of transition radiation, basic equation and algorithm suitable for detailed analysis of transition radiation and optimization of transition radiation detectors in the area of experimental high- energy physics. The results are based on detailed Monte Carlo simulation of transition radiation introduced in GEANT and experimental results. (12 refs).

Nonequilibrium thermodynamic fluctuations and phase transition in black holes

International Nuclear Information System (INIS)

Su, R.; Cai, R.; Yu, P.K.N.

1994-01-01

Landau nonequilibrium fluctuation and phase transition theory is applied to the discussion of the phase transition of black holes. Some second moments of relevant thermodynamical quantities for Kerr-Newman black holes are estimated. A theorem governing the divergence of some second moments and the occurrence of the phase transition in black holes is given

The MSSM Electroweak Phase Transition on the Lattice

CERN Document Server

Laine, Mikko

1998-01-01

We study the MSSM finite temperature electroweak phase transition with lattice Monte Carlo simulations, for a large Higgs mass (m_H ~ 95 GeV) and light stop masses (m_tR ~ 150...160 GeV). We employ a 3d effective field theory approach, where the degrees of freedom appearing in the action are the SU(2) and SU(3) gauge fields, the weakly interacting Higgs doublet, and the strongly interacting stop triplet. We determine the phase diagram, the critical temperatures, the scalar field expectation values, the latent heat, the interface tension and the correlation lengths at the phase transition points. Extrapolating the results to the infinite volume and continuum limits, we find that the transition is stronger than indicated by 2-loop perturbation theory, guaranteeing that the MSSM phase transition is strong enough for baryogenesis in this regime. We also study the possibility of a two-stage phase transition, in which the stop field gets an expectation value in an intermediate phase. We find that a two-stage transi...

Two-step superconducting transition in Cu-V-Si alloys

International Nuclear Information System (INIS)

Sharma, R.G.; Krishna, M.M.; Narlikar, A.V.

1980-01-01

Copper ternary alloys containing small amounts of vanadium and silicon exhibit a two-step superconducting resistive transition. The first transition occurs around 17 K, the transition temperature of β-W V 3 Si, followed by a plateau and a second transition around 10 K. The resistivity, however, does not drop to zero down to 2.5 K. Reduction of the wire diameter causes the two transitions to shift to lower temperatures. Complete superconductivity in these specimens is absent for two reasons. Firstly, the superconducting volume fraction present in these alloy-wires is below the threshold given by either the effective-medium theory or the site percolation theory. Secondly, the superconducting phase V 3 Si does not precipitate in copper matrix in a fine structure and the proximity effect does not operate strongly. Annealing causes the superconducting particles to coalesce and grow in size and suppresses the proximity effect and superconductivity further in these alloy wires. (author)