Luo, Liying
2016-01-01
In many different fields, social scientists desire to understand temporal variation associated with age, time period, and cohort membership. Among methods proposed to address the identification problem in age-period-cohort analysis, the Intrinsic Estimator (IE) is reputed to impose few assumptions and to yield good estimates of the independent effects of age, period, and cohort groups. This article assesses the validity and application scope of IE theoretically and illustrates its properties with simulations. It shows that IE implicitly assumes a constraint on the linear age, period, and cohort effects. This constraint not only depends on the number of age, period, and cohort categories but also has non-trivial implications for estimation. Because this assumption is extremely difficult, if not impossible, to verify in empirical research, IE cannot and should not be used to estimate age, period, and cohort effects. PMID:24072610
Vedøy, Tord F
2014-11-01
This study examined if temporal variations in daily cigarette smoking and never smoking among groups with different levels of education fit the pattern proposed by the theory of diffusion of innovations (TDI), while taking into account the separate effects of age, period and birth cohort (APC). Aggregated data from nationally representative interview surveys from Norway from 1976 to 2010 was used to calculate probabilities of smoking using an APC approach in which the period variable was normalized to pick up short term cyclical effects. Results showed that educational differences in smoking over time were more strongly determined by birth cohort membership than variations in smoking behavior across the life course. The probability of daily smoking decreased faster across cohorts among higher compared to lower educated. In contrast, the change in probability of never having smoked across cohorts was similar in the two education groups, but stronger among men compared to women. Moreover, educational differences in both daily and never smoking increased among early cohorts and leveled off among late cohorts. The results emphasizes the importance of birth cohort for social change and are consistent with TDI, which posits that smoking behavior diffuse through the social structure over time.
Spatial gender-age-period-cohort analysis of pancreatic cancer mortality in Spain (1990–2013)
Etxeberria, Jaione; Goicoa, Tomás; López-Abente, Gonzalo; Riebler, Andrea
2017-01-01
Recently, the interest in studying pancreatic cancer mortality has increased due to its high lethality. In this work a detailed analysis of pancreatic cancer mortality in Spanish provinces was performed using recent data. A set of multivariate spatial gender-age-period-cohort models was considered to look for potential candidates to analyze pancreatic cancer mortality rates. The selected model combines features of APC (age-period-cohort) models with disease mapping approaches. To ensure model identifiability sum-to-zero constraints were applied. A fully Bayesian approach based on integrated nested Laplace approximations (INLA) was considered for model fitting and inference. Sensitivity analyses were also conducted. In general, estimated average rates by age, cohort, and period are higher in males than in females. The higher differences according to age between males and females correspond to the age groups [65, 70), [70, 75), and [75, 80). Regarding the cohort, the greatest difference between men and women is observed for those born between the forties and the sixties. From there on, the younger the birth cohort is, the smaller the difference becomes. Some cohort differences are also identified by regions and age-groups. The spatial pattern indicates a North-South gradient of pancreatic cancer mortality in Spain, the provinces in the North being the ones with the highest effects on mortality during the studied period. Finally, the space-time evolution shows that the space pattern has changed little over time. PMID:28199327
Mixed models, linear dependency, and identification in age-period-cohort models.
O'Brien, Robert M
2017-07-20
This paper examines the identification problem in age-period-cohort models that use either linear or categorically coded ages, periods, and cohorts or combinations of these parameterizations. These models are not identified using the traditional fixed effect regression model approach because of a linear dependency between the ages, periods, and cohorts. However, these models can be identified if the researcher introduces a single just identifying constraint on the model coefficients. The problem with such constraints is that the results can differ substantially depending on the constraint chosen. Somewhat surprisingly, age-period-cohort models that specify one or more of ages and/or periods and/or cohorts as random effects are identified. This is the case without introducing an additional constraint. I label this identification as statistical model identification and show how statistical model identification comes about in mixed models and why which effects are treated as fixed and which are treated as random can substantially change the estimates of the age, period, and cohort effects. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.
Block Constraints in Age-Period-Cohort Models with Unequal-Width Intervals
ERIC Educational Resources Information Center
Luo, Liying; Hodges, James S.
2016-01-01
Age-period-cohort (APC) models are designed to estimate the independent effects of age, time periods, and cohort membership. However, APC models suffer from an identification problem: There are no unique estimates of the independent effects that fit the data best because of the exact linear dependency among age, period, and cohort. Among methods…
Age-period-cohort analysis of hepatitis A incidence rates in Korea from 2002 to 2012.
Seo, Joo Yeon; Choi, Sungyong; Choi, BoYoul; Ki, Moran
2016-01-01
This study aimed to evaluate the epidemiology of hepatitis A in Korea from 2002 to 2012 using age-period-cohort analyses. We used claims data from the Korean National Health Insurance Corporation for the entire population. Census data from 2010 were used as the standard population. The incidence of hepatitis A was assumed to have a Poisson distribution, and the models and effects were evaluated using the intrinsic estimator method, the likelihood ratio, and the Akaike information criterion. The incidence of hepatitis A gradually increased until 2007 (from 17.55 to 35.72 per 100,000 population) and peaked in 2009 (177.47 per 100,000 population). The highest incidence was observed among 27-29-year-old individuals when we omitted data from 2005 to 2007. From 2005 to 2007, the peak incidence was observed among 24-26-year-old individuals, followed by 27-29-year-olds. The best model fits were observed when the age-period-cohort variables were all considered at the same time for males, females, and the whole population. The incidence of hepatitis A exhibited significant age-period-cohort effects; its incidence peaked in 2009 and was especially high among Koreans 20-39 years of age. These epidemiological patterns may help predict when high incidence rates of hepatitis A may occur in developing countries during their socioeconomic development.
Age-period-cohort analysis of hepatitis A incidence rates in Korea from 2002 to 2012
2016-01-01
OBJECTIVES This study aimed to evaluate the epidemiology of hepatitis A in Korea from 2002 to 2012 using age-period-cohort analyses. METHODS We used claims data from the Korean National Health Insurance Corporation for the entire population. Census data from 2010 were used as the standard population. The incidence of hepatitis A was assumed to have a Poisson distribution, and the models and effects were evaluated using the intrinsic estimator method, the likelihood ratio, and the Akaike information criterion. RESULTS The incidence of hepatitis A gradually increased until 2007 (from 17.55 to 35.72 per 100,000 population) and peaked in 2009 (177.47 per 100,000 population). The highest incidence was observed among 27-29-year-old individuals when we omitted data from 2005 to 2007. From 2005 to 2007, the peak incidence was observed among 24-26-year-old individuals, followed by 27-29-year-olds. The best model fits were observed when the age-period-cohort variables were all considered at the same time for males, females, and the whole population. CONCLUSIONS The incidence of hepatitis A exhibited significant age-period-cohort effects; its incidence peaked in 2009 and was especially high among Koreans 20-39 years of age. These epidemiological patterns may help predict when high incidence rates of hepatitis A may occur in developing countries during their socioeconomic development. PMID:27703127
Age-period-cohort analyses of obesity prevalence in US adults.
An, R; Xiang, X
2016-12-01
Age-period-cohort analysis is a stream of methodologies that decompose the temporal trends for disease risk into three time scales-age, calendar year (period) and year of birth (cohort). This study conducted age-period-cohort analyses of obesity prevalence in US adults. Retrospective data analysis. We constructed regression models based on anthropometric data from the 1999-2012 National Health and Nutrition Examination Survey to correct for the self-reported height/weight in the 1984-2014 Behavioral Risk Factor Surveillance System (BRFSS). We estimated fixed-effects age-period-cohort models based on the BRFSS data for the overall adult sample (n = 6,093,293) and by sex and race/ethnicity, adjusting for individual characteristics and the BRFSS survey design. An inverted U-shaped age effect on obesity and a positive period effect characterized by over-time increase in obesity risk independent of age and cohort influences were identified in the overall sample and subgroups by sex and race/ethnicity. From 1984 to 2014, the adjusted obesity prevalence increased by 21.1 percentage points among US adults, and 20.9, 21.6, 21.0, 26.4 and 20.1 percentage points in men, women, non-Hispanic whites, African Americans and Hispanics, respectively. In contrast, no consistent evidence was found in support of the cohort effect-the adjusted obesity risk was comparable across birth cohorts after accounting for the age and period effects. Shifts in the age distribution and nationwide secular changes may have fuelled the obesity epidemic in the USA over the past decades. Reversing the obesity epidemic may require understanding of the nationwide changes over time that affect weight gain across all population subgroups and promoting universal changes to diet, physical activity and the obesogenic environment. Copyright Â© 2016 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.
The marriage boom and marriage bust in the United States: An age-period-cohort analysis.
Schellekens, Jona
2017-03-01
In the 1950s and 1960s there was an unprecedented marriage boom in the United States. This was followed in the 1970s by a marriage bust. Some argue that both phenomena are cohort effects, while others argue that they are period effects. The study reported here tested the major period and cohort theories of the marriage boom and bust, by estimating an age-period-cohort model of first marriage for the years 1925-79 using census microdata. The results of the analysis indicate that the marriage boom was mostly a period effect, although there were also cohort influences. More specifically, the hypothesis that the marriage boom was mostly a response to rising wages is shown to be consistent with the data. However, much of the marriage bust can be accounted for by unidentified cohort influences, at least until 1980.
A web tool for age-period-cohort analysis of cancer incidence and mortality rates.
Rosenberg, Philip S; Check, David P; Anderson, William F
2014-11-01
Age-period-cohort (APC) analysis can inform registry-based studies of cancer incidence and mortality, but concerns about statistical identifiability and interpretability, as well as the learning curves of statistical software packages, have limited its uptake. We implemented a panel of easy-to-interpret estimable APC functions and corresponding Wald tests in R code that can be accessed through a user-friendly Web tool. Input data for the Web tool consist of age-specific numbers of events and person-years over time, in the form of a rate matrix of paired columns. Output functions include model-based estimators of cross-sectional and longitudinal age-specific rates, period and cohort rate ratios that incorporate the overall annual percentage change (net drift), and estimators of the age-specific annual percentage change (local drifts). The Web tool includes built-in examples for teaching and demonstration. User data can be input from a Microsoft Excel worksheet or by uploading a comma-separated-value file. Model outputs can be saved in a variety of formats, including R and Excel. APC methodology can now be carried out through a freely available user-friendly Web tool. The tool can be accessed at http://analysistools.nci.nih.gov/apc/. The Web tool can help cancer surveillance researchers make important discoveries about emerging cancer trends and patterns. ©2014 American Association for Cancer Research.
A Web Tool for Age-Period-Cohort Analysis of Cancer Incidence and Mortality Rates
Rosenberg, Philip S.; Check, David P.; Anderson, William F.
2014-01-01
BACKGROUND Age-period-cohort (APC) analysis can inform registry-based studies of cancer incidence and mortality, but concerns about statistical identifiability and interpretability, as well as the learning curves of statistical software packages, have limited its uptake. METHODS We implemented a panel of easy-to-interpret estimable APC functions and corresponding Wald tests in R code that can be accessed through a user-friendly web tool. RESULTS Input data for the web tool consist of age-specific numbers of events and person-years over time, in the form of a rate matrix of paired columns. Output functions include model-based estimators of cross-sectional and longitudinal age-specific rates; period and cohort rate ratios that incorporate the overall annual percentage change (net drift); and estimators of the age-specific annual percentage change (local drifts). The web tool includes built-in examples for teaching and demonstration. User data can be input from a Microsoft Excel worksheet or by uploading a comma-separated-value (csv) file. Model outputs can be saved in a variety of formats including R and Excel. CONCLUSIONS APC methodology can now be carried out through a freely-available user-friendly web tool. The tool can be accessed at http://analysistools.nci.nih.gov/apc/. IMPACT The web tool can help cancer surveillance researchers make important discoveries about emerging cancer trends and patterns. PMID:25146089
Delaruelle, Katrijn; Buffel, Veerle; Bracke, Piet
2015-11-01
Researchers have recently been investigating the temporal variation in the educational gradient in health. While there is abundant literature concerning age trajectories, theoretical knowledge about cohort differences is relatively limited. Therefore, in analogy with the life course perspective, we introduce two contrasting cohort-specific hypotheses. The diminishing health returns hypothesis predicts a decrease in educational disparities in health across cohorts. By contrast, the cohort accretion hypothesis suggests that the education-health gap will be more pronounced among younger cohorts. To shed light on this, we perform a hierarchical age-period-cohort analysis (HAPC), using data from a subsample of individuals between 25 and 85 years of age (N = 232,573) from 32 countries in the European Social Survey (six waves: 2002-2012). The analysis leads to three important conclusions. First, we observe a widening health gap between different educational levels over the life course. Second, we find that these educational differences in the age trajectories of health seem to strengthen with each successive birth cohort. However, the two age-related effects disappear when we control for employment status, household income, and family characteristics. Last, when adjusting for these mediators, we reveal evidence to support the diminishing health returns hypothesis, implying that it is primarily the direct association between education and health that decreases across cohorts. This finding raises concerns about potential barriers to education being a vehicle for empowerment and the promotion of health.
Clarifying hierarchical age-period-cohort models: A rejoinder to Bell and Jones.
Reither, Eric N; Land, Kenneth C; Jeon, Sun Y; Powers, Daniel A; Masters, Ryan K; Zheng, Hui; Hardy, Melissa A; Keyes, Katherine M; Fu, Qiang; Hanson, Heidi A; Smith, Ken R; Utz, Rebecca L; Yang, Y Claire
2015-11-01
Previously, Reither et al. (2015) demonstrated that hierarchical age-period-cohort (HAPC) models perform well when basic assumptions are satisfied. To contest this finding, Bell and Jones (2015) invent a data generating process (DGP) that borrows age, period and cohort effects from different equations in Reither et al. (2015). When HAPC models applied to data simulated from this DGP fail to recover the patterning of APC effects, B&J reiterate their view that these models provide "misleading evidence dressed up as science." Despite such strong words, B&J show no curiosity about their own simulated data--and therefore once again misapply HAPC models to data that violate important assumptions. In this response, we illustrate how a careful analyst could have used simple descriptive plots and model selection statistics to verify that (a) period effects are not present in these data, and (b) age and cohort effects are conflated. By accounting for the characteristics of B&J's artificial data structure, we successfully recover the "true" DGP through an appropriately specified model. We conclude that B&Js main contribution to science is to remind analysts that APC models will fail in the presence of exact algebraic effects (i.e., effects with no random/stochastic components), and when collinear temporal dimensions are included without taking special care in the modeling process. The expanded list of coauthors on this commentary represents an emerging consensus among APC scholars that B&J's essential strategy--testing HAPC models with data simulated from contrived DGPs that violate important assumptions--is not a productive way to advance the discussion about innovative APC methods in epidemiology and the social sciences. Copyright © 2015 Elsevier Ltd. All rights reserved.
Temporal Trends of Suicide Mortality in Mainland China: Results from the Age-Period-Cohort Framework
Wang, Zhenkun; Wang, Jinyao; Bao, Junzhe; Gao, Xudong; Yu, Chuanhua; Xiang, Huiyun
2016-01-01
The aim of this study is to explore the long-term trends of suicide mortality in China. We implemented the age-period-cohort (APC) framework, using data from the Global Burden of Disease Study 2013. Our results showed that the net drift of suicide mortality was −4.727% (95% CI: −4.821% to −4.634%) per year for men and −6.633% (95% CI: −6.751% to −6.515%) per year for women, and the local drift values were below 0 in all age groups (p < 0.01 for all) for both sexes during the period of 1994–2013. Longitudinal age curves indicated that, in the same birth cohort, suicide death risk increased rapidly to peak at the life stage of 20–24 years old and 15–24 years old for men and women, respectively, and then showed a decelerated decline, followed by a rise thereafter after 54 years old for men and a slight one after 69 years old for women. The estimated period and cohort RRs were found to show similar monotonic downward patterns (significantly with p < 0.01 for all) for both sexes, with more quickly decreasing for women than for men during the whole period. The decreasing trend of suicide was likely to be related to the economic rapid growth, improvements in health care, enhancement on the level of education, and increasing awareness of suicide among the public in China. In addition, fast urbanization and the effective control of pesticides and rodenticides might be the special reasons behind these trends we observed in this study. PMID:27527195
Should age-period-cohort studies return to the methodologies of the 1970s?
Reither, Eric N; Masters, Ryan K; Yang, Yang Claire; Powers, Daniel A; Zheng, Hui; Land, Kenneth C
2015-03-01
Social scientists have recognized the importance of age-period-cohort (APC) models for half a century, but have spent much of this time mired in debates about the feasibility of APC methods. Recently, a new class of APC methods based on modern statistical knowledge has emerged, offering potential solutions. In 2009, Reither, Hauser and Yang used one of these new methods - hierarchical APC (HAPC) modeling - to study how birth cohorts may have contributed to the U.S. obesity epidemic. They found that recent birth cohorts experience higher odds of obesity than their predecessors, but that ubiquitous period-based changes are primarily responsible for the rising prevalence of obesity. Although these findings have been replicated elsewhere, recent commentaries by Bell and Jones call them into question - along with the new class of APC methods. Specifically, Bell and Jones claim that new APC methods do not adequately address model identification and suggest that "solid theory" is often sufficient to remove one of the three temporal dimensions from empirical consideration. They also present a series of simulation models that purportedly show how the HAPC models estimated by Reither et al. (2009) could have produced misleading results. However, these simulation models rest on assumptions that there were no period effects, and associations between period and cohort variables and the outcome were perfectly linear. Those are conditions under which APC models should never be used. Under more tenable assumptions, our own simulations show that HAPC methods perform well, both in recovering the main findings presented by Reither et al. (2009) and the results reported by Bell and Jones. We also respond to critiques about model identification and theoretically-imposed constraints, finding little pragmatic support for such arguments. We conclude by encouraging social scientists to move beyond the debates of the 1970s and toward a deeper appreciation for modern APC methodologies
Should Age-Period-Cohort Studies Return to the Methodologies of the 1970s?
Masters, Ryan K.; Yang, Y. Claire; Powers, Daniel A.; Zheng, Hui; Land, Kenneth C.
2015-01-01
Social scientists have recognized the importance of age-period-cohort (APC) models for half a century, but have spent much of this time mired in debates about the feasibility of APC methods. Recently, a new class of APC methods based on modern statistical knowledge has emerged, offering potential solutions. In 2009, Reither, Hauser and Yang used one of these new methods – hierarchical APC (HAPC) modeling – to study how birth cohorts may have contributed to the U.S. obesity epidemic. They found that recent birth cohorts experience higher odds of obesity than their predecessors, but that ubiquitous period-based changes are primarily responsible for the rising prevalence of obesity. Although these findings have been replicated elsewhere, recent commentaries by Bell and Jones call them into question – along with the new class of APC methods. Specifically, Bell and Jones claim that new APC methods do not adequately address model identification and suggest that “solid theory” is often sufficient to remove one of the three temporal dimensions from empirical consideration. They also present a series of simulation models that purportedly show how the HAPC models estimated by Reither et al. (2009) could have produced misleading results. However, these simulation models rest on assumptions that there were no period effects, and associations between period and cohort variables and the outcome were perfectly linear. Those are conditions under which APC models should never be used. Under more tenable assumptions, our own simulations show that HAPC methods perform well, both in recovering the main findings presented by Reither et al. (2009) and the results reported by Bell and Jones. We also respond to critiques about model identification and theoretically-imposed constraints, finding little pragmatic support for such arguments. We conclude by encouraging social scientists to move beyond the debates of the 1970s and toward a deeper appreciation for modern APC
Wong, Irene O L; Cowling, Benjamin J; Leung, Gabriel M; Schooling, C Mary
2012-01-01
Hong Kong population has experienced drastic changes in its economic development in the 1940s. Taking advantage of Hong Kong's unique demographic and socioeconomic history, characterized by massive, punctuated migration waves from Southern China, and recent, rapid transition from a pre-industrialized society to the first ethnic Chinese community reaching "first world" status over the last 60 years (i.e., in two or three generations), we examined the longitudinal trends in infection related mortality including septicemia compared to trends in non-bacterial pneumonia to generate hypotheses for further testing in other recently transitioned economies and to provide generalized aetiological insights on how economic transition affects infection-related mortality. We used deaths from septicemia and pneumonia not specified as bacterial, and population figures in Hong Kong from 1976-2005. We fitted age-period-cohort models to decompose septicemia and non-bacterial pneumonia mortality rates into age, period and cohort effects. Septicaemia-related deaths increased exponentially with age, with a downturn by period. The birth cohort curves had downward inflections in both sexes in the 1940s, with a steeper deceleration for women. Non-bacterial pneumonia-related deaths also increased exponentially with age, but the birth cohort patterns showed no downturns for those born in the 1940s. The observed changes appeared to suggest that better early life conditions may enable better development of adaptive immunity, thus enhancing immunity against bacterial infections, with greater benefits for women than men. Given the interaction between the immune system and the gonadotropic axis, these observations are compatible with the hypothesis that upregulation of the gonadotropic axis underlies some of the changes in disease patterns with economic development.
Wong, Irene O. L.; Cowling, Benjamin J.; Leung, Gabriel M.; Schooling, C. Mary
2012-01-01
Background Hong Kong population has experienced drastic changes in its economic development in the 1940s. Taking advantage of Hong Kong’s unique demographic and socioeconomic history, characterized by massive, punctuated migration waves from Southern China, and recent, rapid transition from a pre-industrialized society to the first ethnic Chinese community reaching “first world” status over the last 60 years (i.e., in two or three generations), we examined the longitudinal trends in infection related mortality including septicemia compared to trends in non-bacterial pneumonia to generate hypotheses for further testing in other recently transitioned economies and to provide generalized aetiological insights on how economic transition affects infection-related mortality. Methods We used deaths from septicemia and pneumonia not specified as bacterial, and population figures in Hong Kong from 1976–2005. We fitted age-period-cohort models to decompose septicemia and non-bacterial pneumonia mortality rates into age, period and cohort effects. Results Septicaemia-related deaths increased exponentially with age, with a downturn by period. The birth cohort curves had downward inflections in both sexes in the 1940s, with a steeper deceleration for women. Non-bacterial pneumonia-related deaths also increased exponentially with age, but the birth cohort patterns showed no downturns for those born in the 1940s. Conclusion The observed changes appeared to suggest that better early life conditions may enable better development of adaptive immunity, thus enhancing immunity against bacterial infections, with greater benefits for women than men. Given the interaction between the immune system and the gonadotropic axis, these observations are compatible with the hypothesis that upregulation of the gonadotropic axis underlies some of the changes in disease patterns with economic development. PMID:22720008
An International Contrast of Rates of Placental Abruption: An Age-Period-Cohort Analysis
Ananth, Cande V.; Keyes, Katherine M.; Hamilton, Ava; Gissler, Mika; Wu, Chunsen; Liu, Shiliang; Luque-Fernandez, Miguel Angel; Skjærven, Rolv; Williams, Michelle A.; Tikkanen, Minna; Cnattingius, Sven
2015-01-01
Background Although rare, placental abruption is implicated in disproportionately high rates of perinatal morbidity and mortality. Understanding geographic and temporal variations may provide insights into possible amenable factors of abruption. We examined abruption frequencies by maternal age, delivery year, and maternal birth cohorts over three decades across seven countries. Methods Women that delivered in the US (n = 863,879; 1979–10), Canada (4 provinces, n = 5,407,463; 1982–11), Sweden (n = 3,266,742; 1978–10), Denmark (n = 1,773,895; 1978–08), Norway (n = 1,780,271, 1978–09), Finland (n = 1,411,867; 1987–10), and Spain (n = 6,151,508; 1999–12) were analyzed. Abruption diagnosis was based on ICD coding. Rates were modeled using Poisson regression within the framework of an age-period-cohort analysis, and multi-level models to examine the contribution of smoking in four countries. Results Abruption rates varied across the seven countries (3–10 per 1000), Maternal age showed a consistent J-shaped pattern with increased rates at the extremes of the age distribution. In comparison to births in 2000, births after 2000 in European countries had lower abruption rates; in the US there was an increase in rate up to 2000 and a plateau thereafter. No birth cohort effects were evident. Changes in smoking prevalence partially explained the period effect in the US (P = 0.01) and Sweden (P<0.01). Conclusions There is a strong maternal age effect on abruption. While the abruption rate has plateaued since 2000 in the US, all other countries show declining rates. These findings suggest considerable variation in abruption frequencies across countries; differences in the distribution of risk factors, especially smoking, may help guide policy to reduce abruption rates. PMID:26018653
Trends in Hip Fracture Rates in Canada: An Age-Period-Cohort Analysis
Jean, Sonia; O’Donnell, Siobhan; Lagacé, Claudia; Walsh, Peter; Bancej, Christina; Brown, Jacques P.; Morin, Suzanne; Papaioannou, Alexandra; Jaglal, Susan B.; Leslie, William D.
2016-01-01
Age-standardized rates of hip fracture in Canada declined during the period 1985 to 2005. We investigated whether this incidence pattern is explained by period effects, cohort effects, or both. All hospitalizations during the study period with primary diagnosis of hip fracture were identified. Age- and sex-specific hip fracture rates were calculated for nineteen 5-year age groups and four 5-year calendar periods, resulting in 20 birth cohorts. The effect of age, calendar period, and birth cohort on hip fracture rates was assessed using age-period-cohort models as proposed by Clayton and Schiffers. From 1985 to 2005, a total of 570,872 hospitalizations for hip fracture were identified. Age-standardized rates for hip fracture have progressively declined for females and males. The annual linear decrease in rates per 5-year period were 12% for females and 7% for males (both p < 0.0001). Significant birth cohort effects were also observed for both sexes (p < 0.0001). Cohorts born before 1950 had a higher risk of hip fracture, whereas those born after 1954 had a lower risk. After adjusting for age and constant annual linear change (drift term common to both period and cohort effects), we observed a significant nonlinear birth cohort effect for males (p = 0.0126) but not for females (p = 0.9960). In contrast, the nonlinear period effect, after adjustment for age and drift term, was significant for females (p = 0.0373) but not for males (p = 0.2515). For males, we observed no additional nonlinear period effect after adjusting for age and birth cohort, whereas for females, we observed no additional nonlinear birth cohort effect after adjusting for age and period. Although hip fracture rates decreased in both sexes, different factors may explain these changes. In addition to the constant annual linear decrease, nonlinear birth cohort effects were identified for males, and calendar period effects were identified for females as possible explanations. PMID:23426882
Trends in hip fracture rates in Canada: an age-period-cohort analysis.
Jean, Sonia; O'Donnell, Siobhan; Lagacé, Claudia; Walsh, Peter; Bancej, Christina; Brown, Jacques P; Morin, Suzanne; Papaioannou, Alexandra; Jaglal, Susan B; Leslie, William D
2013-06-01
Age-standardized rates of hip fracture in Canada declined during the period 1985 to 2005. We investigated whether this incidence pattern is explained by period effects, cohort effects, or both. All hospitalizations during the study period with primary diagnosis of hip fracture were identified. Age- and sex-specific hip fracture rates were calculated for nineteen 5-year age groups and four 5-year calendar periods, resulting in 20 birth cohorts. The effect of age, calendar period, and birth cohort on hip fracture rates was assessed using age-period-cohort models as proposed by Clayton and Schiffers. From 1985 to 2005, a total of 570,872 hospitalizations for hip fracture were identified. Age-standardized rates for hip fracture have progressively declined for females and males. The annual linear decrease in rates per 5-year period were 12% for females and 7% for males (both p < 0.0001). Significant birth cohort effects were also observed for both sexes (p < 0.0001). Cohorts born before 1950 had a higher risk of hip fracture, whereas those born after 1954 had a lower risk. After adjusting for age and constant annual linear change (drift term common to both period and cohort effects), we observed a significant nonlinear birth cohort effect for males (p = 0.0126) but not for females (p = 0.9960). In contrast, the nonlinear period effect, after adjustment for age and drift term, was significant for females (p = 0.0373) but not for males (p = 0.2515). For males, we observed no additional nonlinear period effect after adjusting for age and birth cohort, whereas for females, we observed no additional nonlinear birth cohort effect after adjusting for age and period. Although hip fracture rates decreased in both sexes, different factors may explain these changes. In addition to the constant annual linear decrease, nonlinear birth cohort effects were identified for males, and calendar period effects were identified for females as possible explanations.
Trends in Ischemic Heart Disease Mortality in Korea, 1985-2009: An Age-period-cohort Analysis
Lee, Hye Ah
2012-01-01
Objectives Economic growth and development of medical technology help to improve the average life expectancy, but the western diet and rapid conversions to poor lifestyles lead an increasing risk of major chronic diseases. Coronary heart disease mortality in Korea has been on the increase, while showing a steady decline in the other industrialized countries. An age-period-cohort analysis can help understand the trends in mortality and predict the near future. Methods We analyzed the time trends of ischemic heart disease mortality, which is on the increase, from 1985 to 2009 using an age-period-cohort model to characterize the effects of ischemic heart disease on changes in the mortality rate over time. Results All three effects on total ischemic heart disease mortality were statistically significant. Regarding the period effect, the mortality rate was decreased slightly in 2000 to 2004, after it had continuously increased since the late 1980s that trend was similar in both sexes. The expected age effect was noticeable, starting from the mid-60's. In addition, the age effect in women was more remarkable than that in men. Women born from the early 1900s to 1925 observed an increase in ischemic heart mortality. That cohort effect showed significance only in women. Conclusions The future cohort effect might have a lasting impact on the risk of ischemic heart disease in women with the increasing elderly population, and a national prevention policy is need to establish management of high risk by considering the age-period-cohort effect. PMID:23091658
Van der Auwera, S; Schomerus, G; Baumeister, S E; Matschinger, H; Angermeyer, M
2017-02-01
Previous cross-sectional studies revealed inconsistent results regarding mental health treatment preferences among the general population. In particular, it is unclear to what extent specific age groups approve psychotherapy or psychotropic medication for the treatment of mental disorders. We explore whether treatment recommendations of either psychotherapy or psychiatric medication change over the lifespan which includes age-related effects due to increasing age of a person, cohort effects that reflect specific opinions during the time a person was born and period effects that reflect societal changes. Using data from three identical population surveys in Germany from 1990, 2001 and 2011 (combined n = 9046), we performed age-period-cohort analyses to determine the pure age, birth cohort and time period effects associated with the specific treatment recommendations for a person with either depression or schizophrenia, using logistic Partial Least-Squares regression models. For both disorders, approval of both psychotherapy and medication for a person with mental illness increases with age. At the same time, younger cohorts showed stronger recommendations particularly for psychotherapy (OR around 1.07 per decade). The strongest effects could be observed for time period with an increase in recommendation between 1990 and 2001 with odds ratio of 2.36 in depression and 2.97 in schizophrenia, respectively. In general, the treatment option that showed the strongest increase in recommendation was medication for schizophrenia and psychotherapy for depression. Underutilisation of psychotherapy in old age seems not to reflect treatment preferences of older persons. Thus, special treatment approaches need to be offered for this group that seems to be willing for psychotherapy but do not yet use it. Cohort patterns suggest that approval of psychotherapy among older persons will likely further increase in the coming years as these people get older. Finally, strong period
Rousselière, Damien; Rousselière, Samira
2017-08-01
The study of European attitudes toward biotechnologies underlines a situation that is relatively contrasting in Europe. However, as different effects of time can influence the social attitudes (a life-cycle effect, a generational effect, and an exogenous temporal effect potentially affecting the entire population), an appropriate methodology should be used. To this end, age-period-cohort-country models have thus been estimated based on Eurobarometer data from 1991 onward. Applied to different data subsets, these models give similar results underlining the importance of the life-cycle effects as well as the heterogeneity of the link between political affiliation and biotechnologies attitudes across the European countries.
Pes, Giovanni Mario; Cocco, Federica; Bibbò, Stefano; Marras, Giuseppina; Dore, Maria Pina
2017-04-01
To examine cancer trend using age-period-cohort analysis with a cohort of patients in Sardinia, Italy, where epidemiological transition occurred between 1950 and 1960. Poisson log-linear regression models were used to analyze time trend in patients undergoing upper endoscopy between 1995 and 2013. A total of 10,546 clinical records (62.2% women) were retrieved. In 541 patients (5.1%), a diagnosis of cancer was reported, more often in men (5.5%) than in women (4.9%). Age and birth cohort were significantly associated with cancer rate according to age-period-cohort analysis (p < 0.0001), whereas the effect of time period was negligible (p = 0.875). An upward trend for all cancers was observed in the younger generations (7.15% before 1950, 8.85% between 1950 and 1960, and 10.7% after 1960). Population aging and increased exposure to cancer risk factors after epidemiological transition were the major determinants associated with cancer in this Sardinian cohort, whereas time period had no effect, ruling out any variation in diagnostic accuracy. These results may facilitate the provision of preventive measures by the health care system, and improve population-tailored cancer screening strategies.
Utada, Mai; Ohno, Yuko; Shimizu, Sachiko; Ito, Yuri; Tsukuma, Hideaki
2012-01-01
In previous studies we predicted future trends in cancer incidence for each prefecture in order to plan cancer control. Those predictions, however, did not take into account the characteristics of each prefecture. We therefore used the results of age-period-cohort analysis of incidence and mortality data of Osaka, and estimated the incidence and mortality of cancers at all sites and selected sites. The results reflect the characteristics of Osaka, which has and is expected to have large number of patients with liver cancer. We believe our results to be useful for planning and evaluating cancer control activities in Osaka. It would be worthwhile to base the estimation of cancer incidence and mortality in each prefecture on each population-based cancer registry.
Wang, Jinyao; Bai, Zhiqiang; Wang, Zhenkun; Yu, Chuanhua
2016-11-17
Background: As one of the most common cancers in the female population, cervical cancer has ranked as the second most incident gynecological cancer in recent years, trailing only breast cancer. We aimed to assess and compare the secular trends in cervical cancer mortality in China and the United States and analyze the independent effects of chronological age, time period and birth cohort using age-period-cohort (APC) analysis. Methods: We performed an age-period-cohort analysis using the intrinsic estimator method to estimate the independent effects of age, time period, and birth cohort on cervical cancer mortality. We collected mortality data for China and the United States from the WHO Mortality Database and China Health Statistical Yearbook database. Results: We examined the general trends in cervical mortality rates in China and the United States during the periods 1988-2012 and 1953-2012, respectively. The age-standardized mortality rates (ASMRs) for cervical cancer in urban China, rural China and the U.S. showed a general decreasing trend during the observation period, except for urban China, which experienced a significant increase beginning in 2002. The mortality rates for cervical cancer in the three areas showed a general increasing trend with age, regardless of the period effect. Period effects declined steadily in both rural China (from 0.19 to -0.26) and the U.S. (from -0.20 to -0.43); however, a slight increasing trend was identified (from -0.25 to 0.33) in urban China, which indicated that the risk of mortality increased with time. Cohort effects peaked in the cohort born in 1911-1915 in both rural China and urban China, declined consistently in the cohort born before 1950, and then decreased again in the cohort born after 1976-1980. The cohort effect in the U.S. peaked in the birth cohort born in 1876-1880, then leveled off and slightly decreased in younger generations. Conclusions: Our study showed that in general, cervical cancer mortality rates
Wang, Jinyao; Bai, Zhiqiang; Wang, Zhenkun; Yu, Chuanhua
2016-01-01
Background: As one of the most common cancers in the female population, cervical cancer has ranked as the second most incident gynecological cancer in recent years, trailing only breast cancer. We aimed to assess and compare the secular trends in cervical cancer mortality in China and the United States and analyze the independent effects of chronological age, time period and birth cohort using age-period-cohort (APC) analysis. Methods: We performed an age-period-cohort analysis using the intrinsic estimator method to estimate the independent effects of age, time period, and birth cohort on cervical cancer mortality. We collected mortality data for China and the United States from the WHO Mortality Database and China Health Statistical Yearbook database. Results: We examined the general trends in cervical mortality rates in China and the United States during the periods 1988–2012 and 1953–2012, respectively. The age-standardized mortality rates (ASMRs) for cervical cancer in urban China, rural China and the U.S. showed a general decreasing trend during the observation period, except for urban China, which experienced a significant increase beginning in 2002. The mortality rates for cervical cancer in the three areas showed a general increasing trend with age, regardless of the period effect. Period effects declined steadily in both rural China (from 0.19 to −0.26) and the U.S. (from −0.20 to −0.43); however, a slight increasing trend was identified (from −0.25 to 0.33) in urban China, which indicated that the risk of mortality increased with time. Cohort effects peaked in the cohort born in 1911–1915 in both rural China and urban China, declined consistently in the cohort born before 1950, and then decreased again in the cohort born after 1976–1980. The cohort effect in the U.S. peaked in the birth cohort born in 1876–1880, then leveled off and slightly decreased in younger generations. Conclusions: Our study showed that in general, cervical cancer
Age-Period-Cohort Analysis of 1990–2003 Incidence Time Trends of Childhood Diabetes in Italy
Bruno, Graziella; Maule, Milena; Merletti, Franco; Novelli, Giulia; Falorni, Alberto; Iannilli, Antonio; Iughetti, Lorenzo; Altobelli, Emma; d'Annunzio, Giuseppe; Piffer, Silvano; Pozzilli, Paolo; Iafusco, Dario; Songini, Marco; Roncarolo, Federico; Toni, Sonia; Carle, Flavia; Cherubini, Valentino
2010-01-01
OBJECTIVE To investigate age-period-cohort effects on the temporal trend of type 1 diabetes in children age 0–14 years in Italian registries. RESEARCH DESIGN AND METHODS This report is based on 5,180 incident cases in the period 1990–2003 from the Registry for Type 1 Diabetes Mellitus in Italy (RIDI). Multilevel (random intercept) Poisson regression models were used to model the effects of sex, age, calendar time, and birth cohorts on temporal trends, taking into account the registry-level variance component. RESULTS The incidence rate was 12.26 per 100,000 person-years and significantly higher in boys (13.13 [95% CI 12.66–13.62]) than in girls (11.35 [10.90–11.82]). Large geographical variations in incidence within Italy were evident; incidence was highest in Sardinia, intermediate in Central-Southern Italy, and high in Northern Italy, particularly in the Trento Province, where the incidence rate was 18.67 per 100,000 person-years. An increasing temporal trend was evident (2.94% per year [95% CI 2.22–3.67]). With respect to the calendar period 1990–1992, the incidence rates increased linearly by 15, 27, 35, and 40% in the following time periods (P for trend < 0.001). With respect to the 1987–1993 birth cohort, the incidence rate ratio increased approximately linearly from 0.63 (95% CI 0.54–0.73) in the 1975–1981 cohort to 1.38 (1.06–1.80) in the 1999–2003 cohort. The best model, however, included sex, age, and a linear time trend (drift). CONCLUSIONS Large geographical variations and an increasing temporal trend in diabetes incidence are evident among type 1 diabetic children in Italy. Age-period-cohort analysis shows that the variation over time has a linear component that cannot be ascribed to either the calendar period or the birth cohort. PMID:20566665
Rughiniș, Cosima; Humă, Bogdana
2015-12-01
In this paper we argue that quantitative survey-based social research essentializes age, through specific rhetorical tools. We outline the device of 'socio-demographic variables' and we discuss its argumentative functions, looking at scientific survey-based analyses of adult scientific literacy, in the Public Understanding of Science research field. 'Socio-demographics' are virtually omnipresent in survey literature: they are, as a rule, used and discussed as bundles of independent variables, requiring little, if any, theoretical and measurement attention. 'Socio-demographics' are rhetorically effective through their common-sense richness of meaning and inferential power. We identify their main argumentation functions as 'structure building', 'pacification', and 'purification'. Socio-demographics are used to uphold causal vocabularies, supporting the transmutation of the descriptive statistical jargon of 'effects' and 'explained variance' into 'explanatory factors'. Age can also be studied statistically as a main variable of interest, through the age-period-cohort (APC) disambiguation technique. While this approach has generated interesting findings, it did not mitigate the reductionism that appears when treating age as a socio-demographic variable. By working with age as a 'socio-demographic variable', quantitative researchers convert it (inadvertently) into a quasi-biological feature, symmetrical, as regards analytical treatment, with pathogens in epidemiological research.
Tu, Yu-Kang; Krämer, Nicole; Lee, Wen-Chung
2012-07-01
In the analysis of trends in health outcomes, an ongoing issue is how to separate and estimate the effects of age, period, and cohort. As these 3 variables are perfectly collinear by definition, regression coefficients in a general linear model are not unique. In this tutorial, we review why identification is a problem, and how this problem may be tackled using partial least squares and principal components regression analyses. Both methods produce regression coefficients that fulfill the same collinearity constraint as the variables age, period, and cohort. We show that, because the constraint imposed by partial least squares and principal components regression is inherent in the mathematical relation among the 3 variables, this leads to more interpretable results. We use one dataset from a Taiwanese health-screening program to illustrate how to use partial least squares regression to analyze the trends in body heights with 3 continuous variables for age, period, and cohort. We then use another dataset of hepatocellular carcinoma mortality rates for Taiwanese men to illustrate how to use partial least squares regression to analyze tables with aggregated data. We use the second dataset to show the relation between the intrinsic estimator, a recently proposed method for the age-period-cohort analysis, and partial least squares regression. We also show that the inclusion of all indicator variables provides a more consistent approach. R code for our analyses is provided in the eAppendix.
Gao, Xudong; Wang, Zhenkun; Kong, Chan; Yang, Fen; Wang, Ying; Tan, Xiaodong
2017-02-23
Background: Esophageal cancer is one of the most common cancers in rural China. The aim of this study was to describe the time trends of esophageal cancer mortality in rural China and to better elucidate the causes of these trends. Methods: The mortality data were obtained from the World Health Organization Mortality Database and the China Health Statistical Yearbook Database. The mortality data were analyzed with age-period-cohort (APC) analysis. Results: Our study indicates that the Age-Standardized Mortality Rates (ASMRs) in rural China generally decreased from 1989 to 2003, and thereafter increased until the year 2008 in both sexes. After 2008, the ASMRs decreased again. The results of APC analysis suggest that the general decrease in esophageal cancer mortality in rural China from 1989 to 2003 might be caused by the downtrend of the cohort effects and period effects, while the general increase in mortality from 2004 to 2008 might be caused by the uptrend of the period effects. The decrease in mortality after 2008 may be relevant to the Four Trillion RMB Investment Plan launched by the Chinese Government. Conclusions: The declining cohort effects were probably related to the improvement of socioeconomic status in childhood and the decreasing consumptions of alcohol drinking and smoking, while the trends of the period effects were relevant to the changes in the dietary pattern. Our findings may help predict future changes in esophageal cancer mortality.
Mortality of breast cancer in Taiwan, 1971-2010: temporal changes and an age-period-cohort analysis.
Ho, M-L; Hsiao, Y-H; Su, S-Y; Chou, M-C; Liaw, Y-P
2015-01-01
The current paper describes the age, period and cohort effects on breast cancer mortality in Taiwan. Female breast cancer mortality data were collected from the Taiwan death registries for 1971-2010. The annual percentage changes, age- standardised mortality rates (ASMR) and age-period-cohort model were calculated. The mortality rates increased with advancing age groups when fixing the period. The percentage change in the breast cancer mortality rate increased from 54.79% at aged 20-44 years, to 149.78% in those aged 45-64 years (between 1971-75 and 2006-10). The mortality rates in the 45-64 age group increased steadily from 1971 to 1975 and 2006-10. The 1951 birth cohorts (actual birth cohort; 1947-55) showed peak mortalities in both the 50-54 and 45-49 age groups. We found that the 1951 birth cohorts had the greatest mortality risk from breast cancer. This might be attributed to the DDT that was used in large amounts to prevent deaths from malaria in Taiwan. However, future researches require DDT data to evaluate the association between breast cancer and DDT use.
Chrisopoulos, Sergio; Luzzi, Liana; Brennan, David S
2013-10-03
The cost of dental care may be a barrier to regular dental attendance with the proportion of the Australian population avoiding or delaying care due to cost increasing since 1994. This paper explores the extent to which age, period and cohort factors have contributed to the variation in avoiding or delaying visiting a dentist because of cost. Data were obtained from four national dental telephone interview surveys of Australian residents aged five years and over conducted in 1994, 1999, 2004 and 2010 (response rates 48%-72%). The trend in the percentage of persons avoiding or delaying visiting a dentist because of cost was analysed by means of a standard cohort table and more formal age-period-cohort analyses using a nested models framework. There was an overall increase in the proportion of people avoiding or delaying visiting a dentist indicating the presence of period effects. Financial barriers were also associated with age such that the likelihood of avoiding because of cost was highest for those in their mid-late twenties and lowest in both children and older adults. Cohort effects were also present although the pattern of effects differed between cohorts. The findings of this study suggest that, in addition to the increase in costs associated with dental care, policies targeting specific age groups and income levels may be contributing to the inequality in access to dental care.
2013-01-01
Background The cost of dental care may be a barrier to regular dental attendance with the proportion of the Australian population avoiding or delaying care due to cost increasing since 1994. This paper explores the extent to which age, period and cohort factors have contributed to the variation in avoiding or delaying visiting a dentist because of cost. Methods Data were obtained from four national dental telephone interview surveys of Australian residents aged five years and over conducted in 1994, 1999, 2004 and 2010 (response rates 48% - 72%). The trend in the percentage of persons avoiding or delaying visiting a dentist because of cost was analysed by means of a standard cohort table and more formal age-period-cohort analyses using a nested models framework. Results There was an overall increase in the proportion of people avoiding or delaying visiting a dentist indicating the presence of period effects. Financial barriers were also associated with age such that the likelihood of avoiding because of cost was highest for those in their mid-late twenties and lowest in both children and older adults. Cohort effects were also present although the pattern of effects differed between cohorts. Conclusion The findings of this study suggest that, in addition to the increase in costs associated with dental care, policies targeting specific age groups and income levels may be contributing to the inequality in access to dental care. PMID:24090111
Gao, Xudong; Wang, Zhenkun; Kong, Chan; Yang, Fen; Wang, Ying; Tan, Xiaodong
2017-01-01
Background: Esophageal cancer is one of the most common cancers in rural China. The aim of this study was to describe the time trends of esophageal cancer mortality in rural China and to better elucidate the causes of these trends. Methods: The mortality data were obtained from the World Health Organization Mortality Database and the China Health Statistical Yearbook Database. The mortality data were analyzed with age-period-cohort (APC) analysis. Results: Our study indicates that the Age-Standardized Mortality Rates (ASMRs) in rural China generally decreased from 1989 to 2003, and thereafter increased until the year 2008 in both sexes. After 2008, the ASMRs decreased again. The results of APC analysis suggest that the general decrease in esophageal cancer mortality in rural China from 1989 to 2003 might be caused by the downtrend of the cohort effects and period effects, while the general increase in mortality from 2004 to 2008 might be caused by the uptrend of the period effects. The decrease in mortality after 2008 may be relevant to the Four Trillion RMB Investment Plan launched by the Chinese Government. Conclusions: The declining cohort effects were probably related to the improvement of socioeconomic status in childhood and the decreasing consumptions of alcohol drinking and smoking, while the trends of the period effects were relevant to the changes in the dietary pattern. Our findings may help predict future changes in esophageal cancer mortality. PMID:28241504
Riebler, Andrea; Held, Leonhard
2017-05-01
The projection of age-stratified cancer incidence and mortality rates is of great interest due to demographic changes, but also therapeutical and diagnostic developments. Bayesian age-period-cohort (APC) models are well suited for the analysis of such data, but are not yet used in routine practice of epidemiologists. Reasons may include that Bayesian APC models have been criticized to produce too wide prediction intervals. Furthermore, the fitting of Bayesian APC models is usually done using Markov chain Monte Carlo (MCMC), which introduces complex convergence concerns and may be subject to additional technical problems. In this paper we address both concerns, developing efficient MCMC-free software for routine use in epidemiological applications. We apply Bayesian APC models to annual lung cancer data for females in five different countries, previously analyzed in the literature. To assess the predictive quality, we omit the observations from the last 10 years and compare the projections with the actual observed data based on the absolute error and the continuous ranked probability score. Further, we assess calibration of the one-step-ahead predictive distributions. In our application, the probabilistic forecasts obtained by the Bayesian APC model are well calibrated and not too wide. A comparison to projections obtained by a generalized Lee-Carter model is also given. The methodology is implemented in the user-friendly R-package BAPC using integrated nested Laplace approximations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Choe, Young-June; Lee, Young Hwa; Cho, Sung-Il
2017-04-01
To characterize the temporal dynamics of mumps epidemiology according to the different vaccine strains used, sex-specific trends were decomposed in an age-period-cohort (APC) analysis for mumps cases reported in South Korea. National surveillance data were used to describe the epidemiology of mumps cases from 2001 to 2015. An APC model was used to break down the reported mumps cases into the effects of age, period, and birth cohort. From 2001 to 2015, the incidence started to increase from fewer than 10 cases to more than 100 cases per 100 000. The incidence rate was highest among males aged 15-17 years during 2013-2015, reaching 508.7 per 100 000 persons. There was an increased incidence during the late teenage years in the 1998-2000 cohort. An age shift towards the earlier teenage years was observed across the 2001-2003 and 2004-2006 cohorts. The risk of mumps increased according to the birth cohort; the net drift from 2001 to 2015 was 27.67 (95% confidence interval 27.5.47-29.90) for males and 27.25 (95% confidence interval 24.91-29.65) for females. The increase in mumps seen in Korea may have been affected by the birth cohort exposed to the Rubini strain; however other factors may have contributed to the increase in non-exposed cohorts. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.
Gill, Tiffany K.; Price, Kay; Warmington, Rosemary; Taylor, Anne W.
2016-01-01
Background The ongoing need for an availability of informal carers is taking on greater relevance as the global burden of disease transitions from acute fatal diseases to long term morbidity. Growing evidence suggests that extra burden on family carers may further impact on their health and ability to provide care. Important as it is to monitor the prevalence of those conditions which influence the burden of disease, it is also important to monitor the prevalence and health profiles of those who provide the informal care. The aim of this study was to demonstrate the prevalence and demographics of adult carers aged 15 and over in the state of South Australia over 20 years between 1994 and 2014. Methods Data from nine representative, cross-sectional population surveys, conducted in South Australia, Australia were used, (total N = 26,788 and n = 1,504 carers). The adjusted prevalence estimate of carers and their demographic characteristics were determined. So as to examine whether there were any generational effects on the prevalence of carers, an Age-Period Cohort (APC) analysis was undertaken. Results The prevalence estimates of carers increased during the two decades from 3.7% in 1994 to 6.7% by 2014. Large increases in the proportion of retired carers, those aged 70 years and over, those carers employed, and those with higher educational qualifications were observed. There were also larger proportions of respondents with a country of birth other than Australia, UK, Ireland and European counties. The APC analysis illustrated an increasing prevalence rate over each decade for carers aged 20–80 years, especially for those over the age of 60 years. Conclusions The results illustrate changing carer characteristics and carer prevalence estimates in South Australia as new generations of carers take on the caring role. There is a need to include questions regarding informal carers within ongoing mainstream population surveys, particularly at state levels, so as to plan
Gero, Krisztina; Eshak, Ehab S.; Ma, Enbo; Takahashi, Hideto; Noda, Hiroyuki; Iso, Hiroyasu
2015-01-01
Background The objective of this study was to examine long-term trends in rates of ischaemic heart disease (IHD) mortality, a leading cause of mortality in Hungary. The study examined the effects of age, period, and cohort on IHD mortality rates and compared mortality rates between the capital (Budapest) and non-capital counties. Methods Data on IHD deaths and population censuses were obtained from the Hungarian Central Statistical Office. Age-period-cohort analysis utilized nine age-group classes for ages 40 to 84 years, eight time periods from 1970 to 2009, and 16 birth cohorts from 1886 to 1969. Results Age-adjusted IHD mortality rates for men and for women generally increased from 1970 to 1993 and from 1980 to 1999, respectively, decreasing thereafter for both sexes. IHD mortality rates for men and for women from Budapest were lower from 1991 and from 1970, respectively, than corresponding rates in non-capital counties, with the difference increasing after 1999. Age had a more significant influence on mortality rates for women than for men. The period effect increased from 1972 to 1982 and decreased thereafter for men, while the period effect decreased consistently for women from 1972 to 2007. The decline in period effect for both sexes was larger for individuals from the capital than for those from non-capital counties. The cohort effect for both sexes declined from birth years 1890 to 1965, with a steeper decline for individuals from the capital than for those from non-capital counties. Conclusions The findings indicate a need for programs in Hungary for IHD prevention, especially for non-capital counties. PMID:25986153
Wang, Zhenkun; Yu, Chuanhua; Wang, Jinyao; Bao, Junzhe; Gao, Xudong; Xiang, Huiyun
2016-07-13
Previous studies suggested that the racial differences in U.S. suicide rates are decreasing, particularly for African Americans, but the cause behind the temporal variations has yet to be determined. This study aims to investigate the long-term trends in suicide mortality in the U.S. between 1983 and 2012 and to examine age-, period-, and cohort-specific effects by gender and race. Suicide mortality data were collected from the Web-based Injury Statistics Query and Reporting System (WISQARS) and analyzed with the Joinpoint regression and age-period-cohort (APC) analysis. We found that although age-standardized rate of suicide in white males, white females, black males, and black females all changed at different degrees, the overall situation almost has not changed since these changes offset each other. By APC analysis, while the age effect on suicide demonstrate an obvious difference between white males and females (with the peak at 75 to 79 for white males and 45 to 54 for white females), young black people are predominantly susceptible to suicide (risk peaks in early 20s for black males and late 20s for black females). Cohort effects all showed a descending trend, except that in white males and females which showed an obvious increase peaked in around cohort 1960. There was a similar period effect trend between different genders in the same race group, but between the races, differences were found in the period before 1990 and after 2000. We confirmed that the distinction in age-specific suicide rate patterns does exist by gender and by race after controlling for period and cohort effects, which suggested that minorities' age patterns of suicide may have been masked up by the white people in the whole population. The differences of period effects and cohort effects between white and black Americans were likely to be mainly explained by the difference in race susceptibility to economic depression.
Pesce, Giancarlo
2016-01-01
Chronic lower respiratory diseases (CLRDs) are a major cause of morbidity and mortality worldwide. The objectives of this study were to estimate the trends in CLRD mortality in Italy, and the specific contributions of age, time period and birth cohort in driving these trends. Population and cause-of-death data in Italy between 1979 and 2010 were collected from the World Health Organization website. Age-specific mortality rates for CLRDs, and effects for age, time period and birth cohort on mortality trends were estimated using age-period-cohort models. Chronic obstructive pulmonary disease (COPD) and chronic bronchitis represent nearly 98% of the deaths from CLRDs. Despite the overall number of deaths have been stable (in men) or increasing (in women), the age-standardised rates have been steadily decreasing from 1979 to 2010, passing from 104.3 to 55.4 per 100 000 person-years in men and from 32.2 to 19.6 per 100 000 person-years in women. The average relative annual decrease was -3.6% in men and -2.7% in women. Since the end of the 1990s, the decreasing trend of CLRD mortality has started to level off, in particular in women. The decrease in CLRD mortality rates has been more accentuated in more recent cohorts and in younger age groups. Both birth cohort and time period significantly affected the CLRD mortality rates, suggesting that changes in the spread of risk factors (smoking habits, early-life and occupational exposures) across different birth cohorts, as well as in advanced in healthcare and medical practice, may have played a major role in secular changes in COPD mortality rates in Italy.
Age-period-cohort analysis of infectious disease mortality in urban-rural China, 1990-2010.
Li, Zhi; Wang, Peigang; Gao, Ge; Xu, Chunling; Chen, Xinguang
2016-03-31
Although a number of studies on infectious disease trends in China exist, these studies have not distinguished the age, period, and cohort effects simultaneously. Here, we analyze infectious disease mortality trends among urban and rural residents in China and distinguish the age, period, and cohort effects simultaneously. Infectious disease mortality rates (1990-2010) of urban and rural residents (5-84 years old) were obtained from the China Health Statistical Yearbook and analyzed with an age-period-cohort (APC) model based on Intrinsic Estimator (IE). Infectious disease mortality is relatively high at age group 5-9, reaches a minimum in adolescence (age group 10-19), then rises with age, with the growth rate gradually slowing down from approximately age 75. From 1990 to 2010, except for a slight rise among urban residents from 2000 to 2005, the mortality of Chinese residents experienced a substantial decline, though at a slower pace from 2005 to 2010. In contrast to the urban residents, rural residents experienced a rapid decline in mortality during 2000 to 2005. The mortality gap between urban and rural residents substantially narrowed during this period. Overall, later birth cohorts experienced lower infectious disease mortality risk. From the 1906-1910 to the 1941-1945 birth cohorts, the decrease of mortality among urban residents was significantly faster than that of subsequent birth cohorts and rural counterparts. With the rapid aging of the Chinese population, the prevention and control of infectious disease in elderly people will present greater challenges. From 1990 to 2010, the infectious disease mortality of Chinese residents and the urban-rural disparity have experienced substantial declines. However, the re-emergence of previously prevalent diseases and the emergence of new infectious diseases created new challenges. It is necessary to further strengthen screening, immunization, and treatment for the elderly and for older cohorts at high risk.
Age-Period-Cohort analysis of mortality due to ischemic heart disease in Japan, 1955 to 2000.
Ma, Enbo; Iso, Hiroyasu; Takahashi, Hideto; Yamagishi, Kazumasa; Tanigawa, Takeshi
2008-06-01
Mortality from ischemic heart disease (IHD) has been showing a marked decline in Japan. The objective of this study was to clarify the effects of age, time period, and cohort on mortality from IHD in Japan from 1955 to 2000. IHD death data from vital statistics and national population surveys were tabulated for 11 5-year age groups (from 30-34 to 80-84) and 10 quinquennial demographic profiles (from 1955 to 2000), to yield 20 5-year birth cohorts (mid-years from 1873 to 1968). The stratified Age-Period-Cohort model with 7 age classes shows: (1) mainly linear age trends for men with IHD, but effects below the linear age trends for women in middle-aged groups (40-74 years); (2) a decline in the effect of time period on IHD for both men and women from 1970 to 1990, and a sharp increase between 1990 and 1995 along with the change of the International Classification of Diseases Code; and (3) 2 patterns for both sexes for non-linear birth cohort effects, an increase (1873-1928) and a decrease (1928-1968) for men, and an increase (1873-1923) and a decrease (1923-1968) for women, with a stronger effect for women than for men born between 1893 and 1938, but the reverse for men and women born between 1938 and 1968. Declining effects of birth cohort on mortality rates of IHD for young and middle-aged people suggest that mortality rates are likely to continue to decrease in Japan.
Tzeng, I-Shiang; Liu, Su-Hsun; Chiou, Yu Ting; Huang, Chien-Hsiung; Lee, Cheng-Jung; Chien, Cheng-Yu; Hsu, Shou-Chien; Weng, Yi-Ming; Chen, Kuan-Fu; Chen, Jih-Chang
2016-12-01
The aim of this study was to determine the age-period-cohort (APC) effects on the rate of infection-related emergency department (ED) visits from septicemia for predicting the same in recent periods.In our study, we investigated the longitudinal trends in septicemia-related visit rates. Using an APC model to decompose the septicemia visit rates into the effects of age, time period, and cohort, and examine whether their effects varied by sex.The septicemia ED visit rate was classified as the International Classification of Disease Code 038 by primary and secondary diagnosis between 1998 and 2012.In both males and females, the visit rate of septicemia showed an increase from 2003 through 2012. An increase in septicemia visit rate after 2003 was observed in all age groups. An APC model indicated a reversal increasing period effect, which increased prominently from 2003 to 2012 in both males and females. The age effect showed an increasing trend. The cohort effect tended to show a slight oscillation from 1913 to 1988. With reference to the prediction of the logarithms of the age-specific 5-year visit rates, we observed that the younger cohorts exhibited a slightly increasing trend, as compared to the older cohorts.The period effect can explain the increase in septicemia visit rates, suggesting the role of screening for septicemia. Furthermore, it is well known that aging is a relevant risk variable for infectious diseases. The present study concludes that the aged population exhibited a strong increasing future trend for septicemia-related ED visit rates.
Znaor, Ariana; Laversanne, Mathieu; Bray, Freddie
2017-09-01
The increasing rates of kidney cancer incidence, reported in many populations globally, have been attributed both to increasing exposures to environmental risk factors, as well as increasing levels of incidental diagnosis due to widespread use of imaging. To better understand these trends, we examine long-term cancer registry data worldwide, focusing on the roles of birth cohort and calendar period, proxies for changes in risk factor prevalence and detection practice respectively. We used an augmented version of the Cancer Incidence in Five Continents series to analyze kidney cancer incidence rates 1978-2007 in 16 geographically representative populations worldwide by sex for ages 30-74, using age-period-cohort (APC) analysis. The full APC model provided the best fit to the data in most studied populations. While kidney cancer incidence rates have been increasing in successive generations born from the early twentieth century in most countries, equivalent period-specific rises were observed from the late-1970s, although these have subsequently stabilized in certain European countries (the Czech Republic, Lithuania, Finland, Spain) as well as Japan from the mid-1990s, and from the mid-2000s, in Colombia, Costa Rica and Australia. Our results indicate that the effects of both birth cohort and calendar period contribute to the international kidney cancer incidence trends. While cohort-specific increases may partly reflect the rising trends in obesity prevalence and the need for more effective primary prevention policies, the attenuations in period-specific increases (observed in 8 of the 16 populations) highlight a possible change in imaging practices that could lead to mitigation of overdiagnosis and overtreatment. © 2017 UICC.
Time trend and age-period-cohort effect on kidney cancer mortality in Europe, 1981–2000
Pérez-Farinós, Napoleón; López-Abente, Gonzalo; Pastor-Barriuso, Roberto
2006-01-01
Background The incorporation of diagnostic and therapeutic improvements, as well as the different smoking patterns, may have had an influence on the observed variability in renal cancer mortality across Europe. This study examined time trends in kidney cancer mortality in fourteen European countries during the last two decades of the 20th century. Methods Kidney cancer deaths and population estimates for each country during the period 1981–2000 were drawn from the World Health Organization Mortality Database. Age- and period-adjusted mortality rates, as well as annual percentage changes in age-adjusted mortality rates, were calculated for each country and geographical region. Log-linear Poisson models were also fitted to study the effect of age, death period, and birth cohort on kidney cancer mortality rates within each country. Results For men, the overall standardized kidney cancer mortality rates in the eastern, western, and northern European countries were 20, 25, and 53% higher than those for the southern European countries, respectively. However, age-adjusted mortality rates showed a significant annual decrease of -0.7% in the north of Europe, a moderate rise of 0.7% in the west, and substantial increases of 1.4% in the south and 2.0% in the east. This trend was similar among women, but with lower mortality rates. Age-period-cohort models showed three different birth-cohort patterns for both men and women: a decrease in mortality trend for those generations born after 1920 in the Nordic countries, a similar but lagged decline for cohorts born after 1930 in western and southern European countries, and a continuous increase throughout all birth cohorts in eastern Europe. Similar but more heterogeneous regional patterns were observed for period effects. Conclusion Kidney cancer mortality trends in Europe showed a clear north-south pattern, with high rates on a downward trend in the north, intermediate rates on a more marked rising trend in the east than in the
Classical approach in atomic physics
NASA Astrophysics Data System (ADS)
Solov'ev, E. A.
2011-12-01
The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincaré section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormgroup symmetry, criterion of accuracy and so on are reviewed as well.
Murphy, Michael; Di Cesare, Mariachiara
2012-11-01
We use an age-period-cohort (APC) model to estimate the contribution of smoking-related mortality to cohort changes in adult mortality in Britain since 1950. We show that lung cancer and overall mortality can be satisfactorily modelled using cohort relative risk and a fixed age pattern. The results of the model suggest that smoking by itself can account for a substantial fraction of change in cohort mortality for those born around the first half of the twentieth century. In particular, smoking provides an explanation for the higher-than-average improvement in the mortality of both males and females born around 1930. Our confidence in the correctness of the results of the models is strengthened by the fact that they are very similar to those of the Peto-Lopez and Preston-Glei-Wilmoth models that estimate the contribution of smoking-related to overall mortality.
Miranda Filho, Adalberto Luiz; Koifman, Rosalina Jorge; Koifman, Sergio; Monteiro, Gina Torres Rego
2014-05-06
Individuals who live in rural areas are at greater risk for brain cancer, and pesticide exposure may contribute to this increased risk. The aims of this research were to analyze the mortality trends and to estimate the age-period-cohort effects on mortality rates from brain cancer in two regions in Rio de Janeiro, Brazil. This descriptive study examined brain cancer mortality patterns in individuals of both sexes, >19 years of age, who died between 1996 and 2010. They were residents of a rural (Serrana) or a non-rural (Metropolitan) area of Rio de Janeiro, Brazil. We estimated mortality trends using Joinpoint Regression analysis. Age-period-cohort models were estimated using Poisson regression analysis. The estimated annual percentage change in mortality caused by brain cancer was 3.8% in the Serrana Region (95% confidence interval (CI): 0.8-5.6) and -0.2% (95% CI: -1.2-0.7) in the Metropolitan Region. The results indicated that the relative risk was higher in the rural region for the more recent birth cohorts (1954 and later). Compared with the reference birth cohort (1945-49, Serrana Region), the relative risk was four times higher for individuals born between 1985 and 1989. The results of this study indicate that there is an increasing trend in brain cancer mortality rates in the rural Serrana Region in Brazil. A cohort effect occurred in the birth cohorts born in this rural area after 1954. At the ecological level, different environmental factors, especially the use of pesticides, may explain regional disparities in the mortality patterns from brain cancers.
Yu, Ruby; Wong, Moses; Chang, Billy; Lai, Xin; Lum, C M; Auyeung, T W; Lee, Jenny; Tsoi, Kelvin; Lee, Ruby; Woo, Jean
2016-12-15
To examine the trends in activities of daily living (ADL) disability in older Chinese adults in Hong Kong between 2001 and 2012. Using data from the Elderly Health Centres (EHCs) of the Department of Health comprising a total of 54 808 community-dwelling Chinese adults aged ≥65 years in 1 early cohort (1904-1917) and 10 3-year birth cohorts (1918-1920, 1921-1923, 1924-1926, 1927-1929, 1930-1932, 1933-1935, 1936-1938, 1939-1941, 1942-1944, 1945-1947), we examined trends in ADL disability by using age-period-cohort (APC) models. ADL disability was defined as being unable to perform at least 1 of 7 ADL activities (bathing, dressing, toileting, transferring, feeding, grooming, walking) independently. Cross-classified random-effects logistic regressions were performed for each of the APC trends with adjustment for age, period, cohort, sociodemographic, lifestyle, comorbidity and self-rated health. The mean age of the cohort was 70.9±4.7 (range 65-99) years. The prevalence rate of ADL disability was 1.6%. ADL disability increased with age (p<0.001) and the gradient of the increase was steeper in the older age groups. At the same age, women (1.7%) were more likely to report ADL disability than men (1.4%, p=0.001). For both genders, there was an increase in ADL disability between 2003 and 2012; adjustment for age, cohort and other covariates has diminished the trends observed among men. There was no cohort effect in ADL disability. ADL disability in older adults has increased over the last decade. Further study is required to identify possible causes behind the disability trends. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
Yu, Ruby; Wong, Moses; Chang, Billy; Lai, Xin; Lum, C M; Auyeung, T W; Lee, Jenny; Tsoi, Kelvin; Lee, Ruby; Woo, Jean
2016-01-01
Background To examine the trends in activities of daily living (ADL) disability in older Chinese adults in Hong Kong between 2001 and 2012. Methods Using data from the Elderly Health Centres (EHCs) of the Department of Health comprising a total of 54 808 community-dwelling Chinese adults aged ≥65 years in 1 early cohort (1904–1917) and 10 3-year birth cohorts (1918–1920, 1921–1923, 1924–1926, 1927–1929, 1930–1932, 1933–1935, 1936–1938, 1939–1941, 1942–1944, 1945–1947), we examined trends in ADL disability by using age-period-cohort (APC) models. ADL disability was defined as being unable to perform at least 1 of 7 ADL activities (bathing, dressing, toileting, transferring, feeding, grooming, walking) independently. Cross-classified random-effects logistic regressions were performed for each of the APC trends with adjustment for age, period, cohort, sociodemographic, lifestyle, comorbidity and self-rated health. Results The mean age of the cohort was 70.9±4.7 (range 65–99) years. The prevalence rate of ADL disability was 1.6%. ADL disability increased with age (p<0.001) and the gradient of the increase was steeper in the older age groups. At the same age, women (1.7%) were more likely to report ADL disability than men (1.4%, p=0.001). For both genders, there was an increase in ADL disability between 2003 and 2012; adjustment for age, cohort and other covariates has diminished the trends observed among men. There was no cohort effect in ADL disability. Conclusions ADL disability in older adults has increased over the last decade. Further study is required to identify possible causes behind the disability trends. PMID:27979837
2014-01-01
Background Individuals who live in rural areas are at greater risk for brain cancer, and pesticide exposure may contribute to this increased risk. The aims of this research were to analyze the mortality trends and to estimate the age-period-cohort effects on mortality rates from brain cancer in two regions in Rio de Janeiro, Brazil. Methods This descriptive study examined brain cancer mortality patterns in individuals of both sexes, >19 years of age, who died between 1996 and 2010. They were residents of a rural (Serrana) or a non-rural (Metropolitan) area of Rio de Janeiro, Brazil. We estimated mortality trends using Joinpoint Regression analysis. Age-period-cohort models were estimated using Poisson regression analysis. Results The estimated annual percentage change in mortality caused by brain cancer was 3.8% in the Serrana Region (95% confidence interval (CI): 0.8–5.6) and -0.2% (95% CI: -1.2–0.7) in the Metropolitan Region. The results indicated that the relative risk was higher in the rural region for the more recent birth cohorts (1954 and later). Compared with the reference birth cohort (1945–49, Serrana Region), the relative risk was four times higher for individuals born between 1985 and 1989. Conclusions The results of this study indicate that there is an increasing trend in brain cancer mortality rates in the rural Serrana Region in Brazil. A cohort effect occurred in the birth cohorts born in this rural area after 1954. At the ecological level, different environmental factors, especially the use of pesticides, may explain regional disparities in the mortality patterns from brain cancers. PMID:24884498
Chauvel, Louis; Leist, Anja K.; Ponomarenko, Valentina
2016-01-01
Birth cohort effects in suicide rates are well established, but to date there is no methodological approach or framework to test the temporal stability of these effects. We use the APC-Detrended (APCD) model to robustly estimate intensity of cohort effects identifying non-linear trends (or ‘detrended’ fluctuations) in suicide rates. The new APC-Hysteresis (APCH) model tests temporal stability of cohort effects. Analysing suicide rates in 25 WHO countries (periods 1970–74 to 2005–09; ages 20–24 to 70–79) with the APCD method, we find that country-specific birth cohort membership plays an important role in suicide rates. Among 25 countries, we detect 12 nations that show deep contrasts among cohort-specific suicide rates including Italy, Australia and the United States. The APCH method shows that cohort fluctuations are not stable across the life course but decline in Spain, France and Australia, whereas they remain stable in Italy, the United Kingdom and the Netherlands. We discuss the Spanish case with elevated suicide mortality of cohorts born 1965–1975 which declines with age, and the opposite case of the United States, where the identified cohort effects of those born around 1960 increase smoothly, but statistically significant across the life course. PMID:27442027
Frenk, Steven M.; Yang, Yang Claire; Land, Kenneth C.
2014-01-01
In recently developed hierarchical age-period-cohort (HAPC) models, inferential questions arise: How can one assess or judge the significance of estimates of individual cohort and period effects in such models? And how does one assess the overall statistical significance of the cohort and/or the period effects? Beyond statistical significance is the question of substantive significance. This paper addresses these questions. In the context of empirical applications of linear and generalized linear mixed-model specifications of HAPC models using data on verbal test scores and voter turnout in U.S. presidential elections, respectively, we describe a two-step approach and a set of guidelines for assessing statistical significance. The guidelines include assessments of patterns of effects and statistical tests both for the effects of individual cohorts and time periods as well as for entire sets of cohorts and periods. The empirical applications show strong evidence that trends in verbal test scores are primarily cohort driven, while voter turnout is primarily a period phenomenon. PMID:25392566
Frenk, Steven M; Yang, Yang Claire; Land, Kenneth C
2013-01-01
In recently developed hierarchical age-period-cohort (HAPC) models, inferential questions arise: How can one assess or judge the significance of estimates of individual cohort and period effects in such models? And how does one assess the overall statistical significance of the cohort and/or the period effects? Beyond statistical significance is the question of substantive significance. This paper addresses these questions. In the context of empirical applications of linear and generalized linear mixed-model specifications of HAPC models using data on verbal test scores and voter turnout in U.S. presidential elections, respectively, we describe a two-step approach and a set of guidelines for assessing statistical significance. The guidelines include assessments of patterns of effects and statistical tests both for the effects of individual cohorts and time periods as well as for entire sets of cohorts and periods. The empirical applications show strong evidence that trends in verbal test scores are primarily cohort driven, while voter turnout is primarily a period phenomenon.
Wang, Zhenkun; Bao, Junzhe; Yu, Chuanhua; Wang, Jinyao; Li, Chunhui
2015-01-01
To describe the temporal trends of breast cancer mortality in East Asia and to better understand the causes of these trends, we analyzed the independent effects of chronological age, time period and birth cohort on breast cancer mortality trends using age-period-cohort (APC) analysis. We chose three main countries in East Asia, namely China, South Korea, and Japan, which have reported death status to the WHO Mortality Database, and used the United States as a comparison population. Our study shows that in general, breast cancer mortality rates in females increased in all three East Asian countries throughout the study period. By APC analysis, we confirmed that there is, in fact, a difference in age-specific mortality rate patterns between the Eastern and the Western countries, which is presumably caused by the two-disease model. While the cause of the decrease from approximately the 1950s generation is still in question, we believe that increasing general awareness and improvements in the health-care system have made a significant contribution to it. Although the age and cohort effects are relatively strong, the period effect may be a more critical factor in the mortality trend, mainly reflecting the increase in exposures to carcinogens and behavioral risk factors. PMID:26690183
Marinaccio, Alessandro; Montanaro, Fabio; Mastrantonio, Marina; Uccelli, Raffaella; Altavista, Pierluigi; Nesti, Massimo; Costantini, Adele Seniori; Gorini, Giuseppe
2005-05-20
Italy was the second main asbestos producer in Europe, after the Soviet Union, until the end of the 1980s, and raw asbestos was imported on a large scale until 1992. The Italian pattern of asbestos consumption lags on average about 10 years behind the United States, Australia, the United Kingdom and the Nordic countries. Measures to reduce exposure were introduced in the mid-1970s in some workplaces. In 1986, limitations were imposed on the use of crocidolite and in 1992 asbestos was definitively banned. We have used primary pleural cancer mortality figures (1970-1999) to predict mortality from mesothelioma among Italian men in the next 30 years by age-cohort-period models and by a model based on asbestos consumption figures. The pleural cancer/mesothelioma ratio and mesothelioma misdiagnosis in the past were taken into account in the analysis. Estimated risks of birth cohorts born after 1945 decrease less quickly in Italy than in other Western countries. The findings predict a peak with about 800 mesothelioma annual deaths in the period 2012-2024. Results estimated using age-period-cohort models were similar to those obtained from the asbestos consumption model.
Wang, Zhenkun; Bao, Junzhe; Yu, Chuanhua; Wang, Jinyao; Li, Chunhui
2015-12-04
To describe the temporal trends of breast cancer mortality in East Asia and to better understand the causes of these trends, we analyzed the independent effects of chronological age, time period and birth cohort on breast cancer mortality trends using age-period-cohort (APC) analysis. We chose three main countries in East Asia, namely China, South Korea, and Japan, which have reported death status to the WHO Mortality Database, and used the United States as a comparison population. Our study shows that in general, breast cancer mortality rates in females increased in all three East Asian countries throughout the study period. By APC analysis, we confirmed that there is, in fact, a difference in age-specific mortality rate patterns between the Eastern and the Western countries, which is presumably caused by the two-disease model. While the cause of the decrease from approximately the 1950s generation is still in question, we believe that increasing general awareness and improvements in the health-care system have made a significant contribution to it. Although the age and cohort effects are relatively strong, the period effect may be a more critical factor in the mortality trend, mainly reflecting the increase in exposures to carcinogens and behavioral risk factors.
Zhang, Li
2017-06-01
This study conducts an age, period, cohort analysis of how religious involvement affects adult health across the life course and over time in the USA. Cross-classified random-effect models are used to examine data drawn from the General Social Survey, 1972-2008. The research shows clear life course patterns, time trends and birth cohort changes in the religious involvement and health relationship with period effects surpassing cohort effects. For the most part, the results show a loss of advantage in health with age for those who are more involved in religion. Period effects are mainly demonstrated by an overall downward trend of self-rated health (SRH) attributable to religious denominational differences and various levels of social integration. Unlike the period effects, the health disparities associated with religious denominational differences fluctuated when cohort progressed. These findings suggest that in general, the positive effect of religious involvement on SRH decreases with age and periods, but its influence on individual SRH fluctuates by cohort. It is expected that a downward trend in SRH attributable to religious involvement will carry on in future.
Barbaric, Jelena; Laversanne, Mathieu; Znaor, Ariana
2017-10-01
The aim of this study was to analyse trends of malignant melanoma incidence in Croatia for men and women of different age groups by birth cohorts and time periods, and to interpret them in the context of national socioeconomic changes over time and the possible implications for future prevention in South-Eastern European postcommunist countries with high mortality rates. We used the Croatian National Cancer Registry data to analyse incidence trends of malignant melanoma of the skin (ICD-9 code 172 and ICD-10 code C43) in men and women aged 25-79 years by age-period-cohort modelling. Over the 25-year period, the incidence was increasing by 5.0% annually in men and 4.6% in women. The age-period model provided the best fit for data in both sexes, with steeply increasing incidence rates, followed by a stabilization after the 2000s. On the cohort scale, incidence rates increased in successive generations of men, whereas in women, the risk of malignant melanoma attenuated in recent cohorts. Even if some progress has been achieved in recent years, the increasing melanoma incidence without concomitant declines in mortality would indicate a need to rekindle prevention efforts in the country taking the specific socioeconomic context into account.
Gangnon, Ronald E; Sprague, Brian L; Stout, Natasha K; Alagoz, Oguz; Weedon-Fekjær, Harald; Holford, Theodore R; Trentham-Dietz, Amy
2015-06-01
The impact of screening mammography on breast cancer incidence is difficult to disentangle from cohort- and age-related effects on incidence. We developed an age-period-cohort model of ductal carcinoma in situ (DCIS) and invasive breast cancer incidence in U.S. females using cancer registry data. Five functions were included in the model to estimate stage-specific effects for age, premenopausal birth cohorts, postmenopausal birth cohorts, period (for all years of diagnosis), and a mammography period effect limited to women ages ≥ 40 years after 1982. Incidence with and without the mammography period effect was calculated. More recent birth cohorts have elevated underlying risk compared with earlier cohorts for both pre- and postmenopausal women. Comparing models with and without the mammography period effect showed that overall breast cancer incidence would have been 23.1% lower in the absence of mammography in 2010 (95% confidence intervals, 18.8-27.4), including 14.7% (9.5-19.3) lower for invasive breast cancer and 54.5% (47.4-59.6) lower for DCIS. Incidence of distant-staged breast cancer in 2010 would have been 29.0% (13.1-48.1) greater in the absence of mammography screening. Mammography contributes to markedly elevated rates of DCIS and early-stage invasive cancers, but also contributes to substantial reductions in the incidence of metastatic breast cancer. Mammography is an important tool for reducing the burden of breast cancer, but future work is needed to identify risk factors accounting for increasing underlying incidence and to distinguish between indolent and potentially lethal early-stage breast cancers that are detected via mammography. ©2015 American Association for Cancer Research.
Bahk, Jinwook; Jang, Sung-Mi; Jung-Choi, Kyunghee
2017-03-31
A steadily increasing pattern of breast cancer mortality has been reported in South Korea since the late 1980s. This paper explored the trends of educational inequalities of female breast cancer mortality between 1983 and 2012 in Korea, and conducted age-period-cohort (APC) analysis by educational level. Age-standardized mortality rates of breast cancer per 100,000 person-years were calculated. Relative index of inequality (RII) for breast cancer mortality was used as an inequality measure. APC analyses were conducted using the Web tool for APC analysis provided by the Division of Cancer Epidemiology and Genetics at the U.S. National Cancer Institute. An increasing trend in breast cancer mortality among Korean women between 1983 and 2012 was due to the increased mortality of the lower education groups (i.e., no formal education or primary education and secondary education groups), not the highest education group. The breast cancer mortality was higher in women with a tertiary education than in women with no education or a primary education during 1983-1992, and the reverse was true in 1993-2012. Consequently, RII was changed from positive to negative associations in the early 2000s. The lower education groups had the increased breast cancer mortality and significant cohort and period effects between 1983 and 2012, whereas the highest group did not. APC analysis by socioeconomic position used in this study could provide an important clue for the causes on breast cancer mortality. The long-term monitoring of socioeconomic patterning in breast cancer risk factors is urgently needed.
Kerr, William C.; Greenfield, Thomas K.; Ye, Yu; Bond, Jason; Rehm, Jürgen
2012-01-01
Aims To estimate age-period-cohort models predicting alcohol volume, heavy drinking and beverage-specific alcohol volume in order to evaluate whether the 1976–1985 birth cohorts drink relatively heavily. Design Data from seven cross-sectional surveys of the US conducted between 1979 and 2010 were utilized in negative binomial generalized linear models of age, period and cohort effects predicting alcohol measures. Setting General population surveys of the US. Participants 36,432 US adults (aged 18 or older). Measurements Monthly number of alcohol drinks, beer, wine and spirits drinks and days drinking 5 or more drinks in the past year derived from beverage-specific graduated frequency questions. Findings Relative to the reference 1956–60 birth cohort, men in the 1976–1980 cohort for were found to consume more alcohol (Incidence rate ratio (IRR) =1.222: CI 1.07–1.39) and to have more 5+ days (IRR=1.365: CI 1.09–1.71) as were men in the 1980–85 cohort for volume (IRR=1.284: CI 1.10–1.50) and 5+ days (IRR=1.437: CI 1.09–1.89). For women, those in the 1980–85 cohort were found to have higher alcohol volume (IRR=1.299: CI 1.07–1.58) and more 5+ days (IRR=1.547: CI 1.01–2.36). Beverage-specific models found different age patterns of volume by beverage with a flat age pattern for both genders’ spirits and women’s wine, an increasing age pattern for men’s wine and a declining age pattern from the early 20’s for beer. Conclusions In the United States, men born between 1976 and 1985, and women born between 1981 and 1985 have higher alcohol consumption than in earlier or later years. PMID:22897662
Seoane-Mato, Daniel; Aragonés, Nuria; Ferreras, Eva; García-Pérez, Javier; Cervantes-Amat, Marta; Fernández-Navarro, Pablo; Pastor-Barriuso, Roberto; López-Abente, Gonzalo
2014-04-11
Although oral cavity, pharyngeal, oesophageal and gastric cancers share some risk factors, no comparative analysis of mortality rate trends in these illnesses has been undertaken in Spain. This study aimed to evaluate the independent effects of age, death period and birth cohort on the mortality rates of these tumours. Specific and age-adjusted mortality rates by tumour and sex were analysed. Age-period-cohort log-linear models were fitted separately for each tumour and sex, and segmented regression models were used to detect changes in period- and cohort-effect curvatures. Among men, the period-effect curvatures for oral cavity/pharyngeal and oesophageal cancers displayed a mortality trend that rose until 1995 and then declined. Among women, oral cavity/pharyngeal cancer mortality increased throughout the study period whereas oesophageal cancer mortality decreased after 1970. Stomach cancer mortality decreased in both sexes from 1965 onwards. Lastly, the cohort-effect curvature showed a certain degree of similarity for all three tumours in both sexes, which was greater among oral cavity, pharyngeal and oesophageal cancers, with a change point in evidence, after which risk of death increased in cohorts born from the 1910-1920s onwards and decreased among the 1950-1960 cohorts and successive generations. This latter feature was likewise observed for stomach cancer. While the similarities of the cohort effects in oral cavity/pharyngeal, oesophageal and gastric tumours support the implication of shared risk factors, the more marked changes in cohort-effect curvature for oral cavity/pharyngeal and oesophageal cancer could be due to the greater influence of some risk factors in their aetiology, such as smoking and alcohol consumption. The increase in oral cavity/pharyngeal cancer mortality in women deserves further study.
Luo, Huabin; Pan, Wei; Sloan, Frank; Feinglos, Mark
2015-01-01
Introduction This study aimed to assess the trends in tooth loss among adults with and without diabetes mellitus in the United States and racial/ethnic disparities in tooth loss patterns, and to evaluate trends in tooth loss by age, birth cohorts, and survey periods. Methods Data came from 9 waves of the National Health and Nutrition Examination Survey (NHANES) from 1971 through 2012. The trends in the estimated tooth loss in people with and without diabetes were assessed by age groups, survey periods, and birth cohorts. The analytical sample was 37,609 dentate (ie, with at least 1 permanent tooth) adults aged 25 years or older. We applied hierarchical age-period-cohort cross-classified random-effects models for the trend analysis. Results The estimated number of teeth lost among non-Hispanic blacks with diabetes increased more with age than that among non-Hispanic whites with diabetes (z = 4.05, P < .001) or Mexican Americans with diabetes (z = 4.38, P < .001). During 1971–2012, there was a significant decreasing trend in the number of teeth lost among non-Hispanic whites with diabetes (slope = −0.20, P < .001) and non-Hispanic blacks with diabetes (slope = −0.37, P < .001). However, adults with diabetes had about twice the tooth loss as did those without diabetes. Conclusion Substantial differences in tooth loss between adults with and without diabetes and across racial/ethnic groups persisted over time. Appropriate dental care and tooth retention need to be further promoted among adults with diabetes. PMID:26632952
Kraus, Ludwig; Østhus, Ståle; Amundsen, Ellen J; Piontek, Daniela; Härkönen, Janne; Legleye, Stéphane; Bloomfield, Kim; Mäkelä, Pia; Landberg, Jonas; Törrönen, Jukka
2015-09-01
To investigate age, period and cohort effects on time trends of alcohol-related mortality in countries with different drinking habits and alcohol policies. Age-period-cohort (APC) analyses on alcohol-related mortality were conducted in Denmark, Finland, Norway, Sweden, France and Germany. Cases included alcohol-related deaths in the age range 20-84 years between 1980 and 2009. Mortality data were taken from national causes of death registries and covered the ICD codes alcoholic psychosis, alcohol use disorders, alcoholic liver disease and toxic effect of alcohol. In all countries changes across age, period and cohort were found to be significant for both genders [effect value with confidence interval (CI) shown in Supporting information, Table S1]. Period effects pointed to an increase in alcohol-related mortality in Denmark, Finland and Germany and a slightly decreasing trend in Sweden, while in Norway an inverse U-shaped curve and in France a U-shaped curve was found. Compared with the cohorts born before 1960, the risk of alcohol-related mortality declined substantially in cohorts born in the 1960s and later. Pairwise between-country comparisons revealed more statistically significant differences for period (P < 0.001 for all 15 comparisons by gender) than for age [P < 0.001 in seven (men) and four (women) of 15 comparisons] or cohort [P < 0.01 in two (men) and three (women) of 15 comparisons]. Strong period effects suggest that temporal changes in alcohol-related mortality in Denmark, Finland, Norway, Sweden, France and Germany between 1980 and 2009 were related to secular differences affecting the whole population and that these effects differed across countries. © 2015 Society for the Study of Addiction.
Lisonkova, Sarka; Lavery, Jessica A; Ananth, Cande V; Chen, Innie; Muraca, Giulia; Cundiff, Geoffrey W; Joseph, K S
2016-08-01
The rates of cesarean delivery have increased over time in industrialized countries, while the rates of instrumental vaginal delivery have declined. Instrumental vaginal delivery and obstetric trauma are risk factors for pelvic floor disorders. We carried out a population-based study to quantify the association between temporal changes in obstetric trauma during childbirth and temporal changes in surgery for pelvic organ prolapse. We designed a retrospective analysis to examine age-specific trends in vaginal and cesarean delivery, obstetric trauma, and surgery for pelvic organ prolapse among all women (pregnant and nonpregnant) in Washington State, from 1987 through 2009. Cases of obstetric trauma (including severe perineal tears and high vaginal lacerations) and inpatient surgery for pelvic organ prolapse were identified among all hospitalizations. Temporal trends and age-period-cohort regression analyses were used to quantify the time period, age, and birth cohort effects among women born from 1920 through 1980. From 1987 through 2009, cesarean delivery rates among women aged 15-44 years increased from 12.7-18.1 per 1000 women, vaginal delivery rates remained stable, and instrumental vaginal delivery rates declined from 6.3-3.9 per 1000 women. Obstetric trauma decreased from 6.7 in 1987 to 2.5 per 1000 women aged 15-44 years in 2009. Surgery for pelvic organ prolapse decreased from 2.1 in 1987 to 1.4 per 1000 women aged 20-84 years in 2009. Obstetric trauma rates in 1987 through 1999 among women 15-44 years old were strongly correlated with the rates of surgery for pelvic organ prolapse among women 25-54 years of age 10 years later in 1997 through 2009 (correlation coefficient 0.87, P < .001). Similarly, rates of midpelvic forceps delivery in 1987 through 1999 were correlated with the rates of surgery for pelvic organ prolapse 10 years later (correlation coefficient 0.72, P < .01). Regression analyses showed a strong effect of age on surgery for prolapse
Quantum approach to classical statistical mechanics.
Somma, R D; Batista, C D; Ortiz, G
2007-07-20
We present a new approach to study the thermodynamic properties of d-dimensional classical systems by reducing the problem to the computation of ground state properties of a d-dimensional quantum model. This classical-to-quantum mapping allows us to extend the scope of standard optimization methods by unifying them under a general framework. The quantum annealing method is naturally extended to simulate classical systems at finite temperatures. We derive the rates to assure convergence to the optimal thermodynamic state using the adiabatic theorem of quantum mechanics. For simulated and quantum annealing, we obtain the asymptotic rates of T(t) approximately (pN)/(k(B)logt) and gamma(t) approximately (Nt)(-c/N), for the temperature and magnetic field, respectively. Other annealing strategies are also discussed.
Quantum cryptography approaching the classical limit.
Weedbrook, Christian; Pirandola, Stefano; Lloyd, Seth; Ralph, Timothy C
2010-09-10
We consider the security of continuous-variable quantum cryptography as we approach the classical limit, i.e., when the unknown preparation noise at the sender's station becomes significantly noisy or thermal (even by as much as 10(4) times greater than the variance of the vacuum mode). We show that, provided the channel transmission losses do not exceed 50%, the security of quantum cryptography is not dependent on the channel transmission, and is therefore incredibly robust against significant amounts of excess preparation noise. We extend these results to consider for the first time quantum cryptography at wavelengths considerably longer than optical and find that regions of security still exist all the way down to the microwave.
Rediscovering the Classics: The Project Approach.
ERIC Educational Resources Information Center
Townsend, Ruth; Lubell, Marcia
Focusing on seven classics of literature that are most challenging for teachers and students, but which are also a part of the high school literary canon, this book shares ways to create a learner-centered classroom for the study of literature. For each of the seven classics, the book "walks teachers through" the teaching-learning…
Rediscovering the Classics: The Project Approach.
ERIC Educational Resources Information Center
Townsend, Ruth; Lubell, Marcia
Focusing on seven classics of literature that are most challenging for teachers and students, but which are also a part of the high school literary canon, this book shares ways to create a learner-centered classroom for the study of literature. For each of the seven classics, the book "walks teachers through" the teaching-learning…
Classical field approach to quantum weak measurements.
Dressel, Justin; Bliokh, Konstantin Y; Nori, Franco
2014-03-21
By generalizing the quantum weak measurement protocol to the case of quantum fields, we show that weak measurements probe an effective classical background field that describes the average field configuration in the spacetime region between pre- and postselection boundary conditions. The classical field is itself a weak value of the corresponding quantum field operator and satisfies equations of motion that extremize an effective action. Weak measurements perturb this effective action, producing measurable changes to the classical field dynamics. As such, weakly measured effects always correspond to an effective classical field. This general result explains why these effects appear to be robust for pre- and postselected ensembles, and why they can also be measured using classical field techniques that are not weak for individual excitations of the field.
NASA Astrophysics Data System (ADS)
Henner, Victor K.; Klots, Andrey; Belozerova, Tatyana
2016-12-01
Problems of interacting quantum magnetic moments become exponentially complex with increasing number of particles. As a result, classical equations are often used to model spin systems. In this paper we show that a classical spins based approach can be used to describe the phenomena essentially quantum in nature such as of the Pake doublet.
An Approach to Teaching Classical Chinese Poetry.
ERIC Educational Resources Information Center
Hung, Ming-shui
1980-01-01
English translations can be used to teach classical Chinese poetry to students above the intermediate level who have a limited vocabulary. To overcome this deficiency, and to bridge the gap between vernacular and literary Chinese, several texts are suggested. Examples are given to show the benefit of English translations. (PJM)
Anderson, R W G; Searson, D J
2015-02-01
A novel application of age-period-cohort methods are used to explain changes in vehicle based crash rates in New South Wales, Australia over the period 2003-2010. Models are developed using vehicle age, crash period and vehicle cohort to explain changes in the rate of single vehicle driver fatalities and injuries in vehicles less than 13 years of age. Large declines in risk are associated with vehicle cohorts built after about 1996. The decline in risk appears to have accelerated to 12 percent per vehicle cohort year for cohorts since 2004. Within each cohort, the risk of crashing appears to be a minimum at two years of age and increases as the vehicle ages beyond this. Period effects (i.e., other road safety measures) between 2003 and 2010 appear to have contributed to declines of up to about two percent per annum to the driver-fatality single vehicle crash rate, and possibly only negligible improvements to the driver-injury single vehicle crash rate. Vehicle improvements appear to have been responsible for a decline in per-vehicle crash risk of at least three percent per calendar year for both severity levels over the same period. Given the decline in risk associated with more recent vehicle cohorts and the dynamics of fleet turnover, continued declines in per-vehicle crash risk over coming years are almost certain.
Teaching Classical Statistical Mechanics: A Simulation Approach.
ERIC Educational Resources Information Center
Sauer, G.
1981-01-01
Describes a one-dimensional model for an ideal gas to study development of disordered motion in Newtonian mechanics. A Monte Carlo procedure for simulation of the statistical ensemble of an ideal gas with fixed total energy is developed. Compares both approaches for a pseudoexperimental foundation of statistical mechanics. (Author/JN)
New Approaches to the Teaching of the Classics.
ERIC Educational Resources Information Center
Masciantonio, Rudolph, Ed.; Weislogel, Stephen, Ed.
This four-part report of the 1971-72 Classical Association of the Atlantic States Working Committee deals with the rationale for new approaches and curriculums for schools and colleges. Implications of the new approaches in teacher education are also teated. The major section treating new model curriculums and approaches includes discussion of:…
A Lagrangian approach to classical thermodynamics
NASA Astrophysics Data System (ADS)
Stokes, A.
2017-02-01
The specification of microstates of interacting dynamical systems is different in Lagrangian and Hamiltonian approaches whenever the interaction Lagrangian depends on generalised velocities. In almost all cases of physical interest however, velocity-dependent interaction Lagrangians do not couple velocities belonging to different subsystems. For these cases we define reduced system and bath Lagrangian macrostates, which like the underlying microstates differ from their Hamiltonian counterparts. We then derive exact first and second laws of thermodynamics without any modification of the original system and bath quantities. This approach yields manifestly gauge-invariant definitions of work and free energy, and a gauge-invariant Jarzynski equality is derived. The formalism is applied in deriving the thermodynamic laws for a material system within the radiation reservoir. The Lagrangian partition of the total energy is manifestly gauge-invariant and is in accordance with Poynting's theorem.
Systems versus Classical Approach to Warfare
2009-01-01
events at others. In sequencing and synchronizing the use of military and non - military sources of power, operational com- manders must have the ability...approach, regardless of their differences, essen- tially share the mechanistic or Newtonian view of warfare. They believe that the information age...nonlinear.45 The Newtonian view of the world is that of a giant machine. Everything runs smoothly, precisely, and predictably. Everything is measurable.46
Sala, Carole; Morignat, Eric; Ducrot, Christian; Calavas, Didier
2009-07-01
An age-period-cohort (APC) analysis was used to assess the trend in prevalence of bovine spongiform encephalopathy (BSE) in France over time in relation to the control measures adopted since onset of the epidemic. Restricted cubic regression splines were used to model the functional forms of the non-linear effects of age at screening, birth cohort and date of diagnosis of the tested animals. The data of the 2001-2007 period of surveillance was analysed using 1-year categorisation. A categorical analysis was performed as control to check the accuracy of the sets of knots in the spline models, which were selected according to the Akaike Information Criterion (AIC). Knot selection was based on a priori knowledge of the disease and the dates of implementation of the five main BSE control measures. It was assumed that disease prevalence was a function of exposure to BSE and that changes in the exposure of cattle to BSE were mainly due to the control measures. The effects of the five main control measures were discussed in relation to the trend in BSE risk for the successive birth cohorts. The six selected models confirmed that all measures participated in disease control. However, characterization of the respective effect of individual measures was not straightforward due to the very low disease prevalence, incompletely tested cohorts and probably cumulative and overlapping effects of successive measures. The ban of importation of meat and bone meal (MBM) from the UK and the ban of use of MBM in bovines were insufficient to control the epidemic. The decline in the BSE epidemic more likely originated from implementation of the ban of MBM use in all ruminants in 1994, whose effect was probably reinforced by the evolution in perception of the BSE risk following evidence of BSE transmission to humans. Finally, the respective effects of the last two measures (prohibition of the use of specific risk material in 1996 and total MBM ban in 2000) could not be characterized as
Classical mechanics approach applied to analysis of genetic oscillators.
Vasylchenkova, Anastasiia; Mraz, Miha; Zimic, Nikolaj; Moskon, Miha
2016-04-05
Biological oscillators present a fundamental part of several regulatory mechanisms that control the response of various biological systems. Several analytical approaches for their analysis have been reported recently. They are, however, limited to only specific oscillator topologies and/or to giving only qualitative answers, i.e., is the dynamics of an oscillator given the parameter space oscillatory or not. Here we present a general analytical approach that can be applied to the analysis of biological oscillators. It relies on the projection of biological systems to classical mechanics systems. The approach is able to provide us with relatively accurate results in the meaning of type of behaviour system reflects (i.e. oscillatory or not) and periods of potential oscillations without the necessity to conduct expensive numerical simulations. We demonstrate and verify the proposed approach on three different implementations of amplified negative feedback oscillator.
Path integral approach to electron scattering in classical electromagnetic potential
NASA Astrophysics Data System (ADS)
Chuang, Xu; Feng, Feng; Ying-Jun, Li
2016-05-01
As is known to all, the electron scattering in classical electromagnetic potential is one of the most widespread applications of quantum theory. Nevertheless, many discussions about electron scattering are based upon single-particle Schrodinger equation or Dirac equation in quantum mechanics rather than the method of quantum field theory. In this paper, by using the path integral approach of quantum field theory, we perturbatively evaluate the scattering amplitude up to the second order for the electron scattering by the classical electromagnetic potential. The results we derive are convenient to apply to all sorts of potential forms. Furthermore, by means of the obtained results, we give explicit calculations for the one-dimensional electric potential. Project supported by the National Natural Science Foundation of China (Grant Nos. 11374360, 11405266, and 11505285) and the National Basic Research Program of China (Grant No. 2013CBA01504).
Spinor dipolar bose-einstein condensates: classical spin approach.
Takahashi, M; Ghosh, Sankalpa; Mizushima, T; Machida, K
2007-06-29
Bose-Einstein condensates which are dominated by magnetic dipole-dipole interaction are discussed under spinful situations. We treat the spin degrees of freedom as a classical spin vector, approaching from the large spin limit to obtain an effective minimal Hamiltonian. This is a version extended from a nonlinear sigma model. By solving the Gross-Pitaevskii equation, we find several novel spin textures where the mass density and spin density are strongly coupled, depending upon trap geometries due to the long-range and anisotropic natures of the dipole-dipole interaction.
Spinor Dipolar Bose-Einstein Condensates: Classical Spin Approach
Takahashi, M.; Mizushima, T.; Machida, K.; Ghosh, Sankalpa
2007-06-29
Bose-Einstein condensates which are dominated by magnetic dipole-dipole interaction are discussed under spinful situations. We treat the spin degrees of freedom as a classical spin vector, approaching from the large spin limit to obtain an effective minimal Hamiltonian. This is a version extended from a nonlinear sigma model. By solving the Gross-Pitaevskii equation, we find several novel spin textures where the mass density and spin density are strongly coupled, depending upon trap geometries due to the long-range and anisotropic natures of the dipole-dipole interaction.
Revisiting a Constructive Classic: Wright's Physical Disability: A Psychosocial Approach
Dunn, Dana S.; Elliott, Timothy R.
2008-01-01
Beatrice A. Wright's (1960) classic book, Physical Disability: A Psychological Approach is a landmark publication in rehabilitation psychology. The authors believe that Division 22's forthcoming 50th anniversary, the results of a recent survey on essential readings in rehabilitation psychology, and a public critique concerning the relevance of individuating language in psychology are compelling reasons for revisiting the influence of Physical Disability. After discussing these catalysts, the authors review the book's history, scholarly impact, and link to positive disciplinary directions. The authors conclude by encouraging rehabilitation psychologists and other members of the discipline to (re)acquaint themselves with this important book and the timeless concepts it espouses. PMID:19079791
Pulse-noise approach for classical spin systems.
Garanin, D A
2017-01-01
For systems of classical spins interacting with the bath via damping and thermal noise, an approach is suggested to replace the white noise by a pulse noise acting at regular time intervals Δt, within which the system evolves conservatively. The method is working well in the typical case of a small dimensionless damping constant λ and allows a considerable speedup of computations by using high-order numerical integrators with a large time step δt (up to a fraction of the precession period), while keeping δt≪Δt to reduce the relative contribution of noise-related operations. In cases when precession can be discarded, δt can be increased up to a fraction of the relaxation time ∝1/λ that leads to a further speedup. This makes equilibration speed comparable with that of the Metropolis Monte Carlo method. The pulse-noise approach is tested on single-spin and multispin models.
Pulse-noise approach for classical spin systems
NASA Astrophysics Data System (ADS)
Garanin, D. A.
2017-01-01
For systems of classical spins interacting with the bath via damping and thermal noise, an approach is suggested to replace the white noise by a pulse noise acting at regular time intervals Δ t , within which the system evolves conservatively. The method is working well in the typical case of a small dimensionless damping constant λ and allows a considerable speedup of computations by using high-order numerical integrators with a large time step δ t (up to a fraction of the precession period), while keeping δ t ≪Δ t to reduce the relative contribution of noise-related operations. In cases when precession can be discarded, δ t can be increased up to a fraction of the relaxation time ∝1 /λ that leads to a further speedup. This makes equilibration speed comparable with that of the Metropolis Monte Carlo method. The pulse-noise approach is tested on single-spin and multispin models.
A "Classic Papers" Approach to Teaching Undergraduate Organometallic Chemistry
NASA Astrophysics Data System (ADS)
Duncan, Andrew P.; Johnson, Adam R.
2007-03-01
We have structured an upper-level undergraduate course in organometallic chemistry on a selection of "classic" publications in the field. This approach offers students a richly contextual introduction to many of the fundamental tenets of the discipline. After a brief introduction to the field led by the faculty, the students themselves are responsible for researching and presenting selected papers to their classmates for analysis and discussion. Beyond mastery of basic organometallic principles, course goals for the students include improved proficiency in using the primary chemical literature and increased experience and confidence in researching, preparing, and delivering an informative oral presentation in individual and collaborative settings. Student performance is assessed based on performance on open-ended, take-home exams, quality of presentations, and contribution to in-class discussions. Student end-of-term survey responses indicate that this class model is successful as an introduction to organometallic chemistry.
Classical and Modern Approaches Used for Viral Hepatitis Diagnosis
Heiat, Mohammad; Ranjbar, Reza; Alavian, Seyed Moayed
2014-01-01
Context: Viral hepatitis diagnosis is an important issue in the treatment procedure of this infection. Late diagnosis and delayed treatment of viral hepatitis infections can lead to irreversible liver damages and occurrence of liver cirrhosis and hepatocellular carcinoma. A variety of laboratory methods including old and new technologies are being applied to detect hepatitis viruses. Here we have tried to review, categorize, compare and illustrate the classical and modern approaches used for diagnosis of viral hepatitis. Evidence Acquisition: In order to achieve a comprehensive aspect in viral hepatitis detection methods, an extensive search using related keywords was done in major medical library and data were collected, categorized and summarized in different sections. Results: Analyzing of collected data resulted in the wrapping up the hepatitis virus detection methods in separate sections including 1) immunological methods such as enzyme immunoassay (EIA), radio-immunoassay (RIA) immuno-chromatographic assay (ICA), and immuno-chemiluminescence 2) molecular approaches including non-amplification and amplification based methods, and finally 3) advanced biosensors such as mass-sensitive, electrical, electrochemical and optical based biosensors and also new generation of detection methods. Conclusions: Detection procedures in the clinical laboratories possess a large diversity; each has their individual advantages and facilities' differences. PMID:24829586
Phosphoproteomics by mass spectrometry and classical protein chemistry approaches.
Salih, Erdjan
2005-01-01
The general fields of biological sciences have seen phenomenal transformations in the past two decades at the level of data acquisition, understanding biological processes, and technological developments. Those advances have been made partly because of the advent of molecular biology techniques (which led to genomics) coupled to the advances made in mass spectrometry (MS) to provide the current capabilities and developments in proteomics. However, our current knowledge that approximately 30,000 human genes may code for up to 1 million or more proteins disengage the interface between the genome sequence database algorithms and MS to generate a major interest in independent de novo MS/MS sequence determination. Significant progress has been made in this area through procedures to covalently modify peptide N- and C-terminal amino-acids by sulfonation and guanidination to permit rapid de novo sequence determination by MS/MS analysis. A number of strategies that have been developed to perform qualitative and quantitative proteomics range from 2D-gel electrophoresis, affinity tag reagents, and stable-isotope labeling. Those procedures, combined with MS/MS peptide sequence analysis at the subpicomole level, permit the rapid and effective identification and quantification of a large number of proteins within a given biological sample. The identification of proteins per se, however, is not always sufficient to interpret biological function because many of the naturally occurring proteins are post-translationally modified. One such modification is protein phosphorylation, which regulates a large array of cellular biochemical pathways of the biological system. Traditionally, the study of phosphoprotein structure-function relationships involved classical protein chemistry approaches that required protein purification, peptide mapping, and the identification of the phosphorylated peptide regions and sites by N-terminal sequence analysis. Recent advances made in mass
Modern versus Tradition: Are There Two Different Approaches to Reading of the Confucian Classics?
ERIC Educational Resources Information Center
Cheng, Chung-yi
2016-01-01
How to read the Confucian Classics today? Scholars with philosophical training usually emphasize that the philosophical approach, in comparison with the classicist and historical ones, is the best way to read the Confucian Classics, for it can dig out as much intellectual resources as possible from the classical texts in order to show their modern…
Hybrid Quantum-Classical Approach to Quantum Optimal Control.
Li, Jun; Yang, Xiaodong; Peng, Xinhua; Sun, Chang-Pu
2017-04-14
A central challenge in quantum computing is to identify more computational problems for which utilization of quantum resources can offer significant speedup. Here, we propose a hybrid quantum-classical scheme to tackle the quantum optimal control problem. We show that the most computationally demanding part of gradient-based algorithms, namely, computing the fitness function and its gradient for a control input, can be accomplished by the process of evolution and measurement on a quantum simulator. By posing queries to and receiving answers from the quantum simulator, classical computing devices update the control parameters until an optimal control solution is found. To demonstrate the quantum-classical scheme in experiment, we use a seven-qubit nuclear magnetic resonance system, on which we have succeeded in optimizing state preparation without involving classical computation of the large Hilbert space evolution.
Hybrid Quantum-Classical Approach to Quantum Optimal Control
NASA Astrophysics Data System (ADS)
Li, Jun; Yang, Xiaodong; Peng, Xinhua; Sun, Chang-Pu
2017-04-01
A central challenge in quantum computing is to identify more computational problems for which utilization of quantum resources can offer significant speedup. Here, we propose a hybrid quantum-classical scheme to tackle the quantum optimal control problem. We show that the most computationally demanding part of gradient-based algorithms, namely, computing the fitness function and its gradient for a control input, can be accomplished by the process of evolution and measurement on a quantum simulator. By posing queries to and receiving answers from the quantum simulator, classical computing devices update the control parameters until an optimal control solution is found. To demonstrate the quantum-classical scheme in experiment, we use a seven-qubit nuclear magnetic resonance system, on which we have succeeded in optimizing state preparation without involving classical computation of the large Hilbert space evolution.
Dynamic scaling at classical phase transitions approached through nonequilibrium quenching
NASA Astrophysics Data System (ADS)
Liu, Cheng-Wei; Polkovnikov, Anatoli; Sandvik, Anders W.
2014-02-01
We use Monte Carlo simulations to demonstrate generic scaling aspects of classical phase transitions approached through a quench (or annealing) protocol where the temperature changes as a function of time with velocity v. Using a generalized Kibble-Zurek ansatz, we demonstrate dynamic scaling for different types of stochastic dynamics (Metropolis, Swendsen-Wang, and Wolff) on Ising models in two and higher dimensions. We show that there are dual scaling functions governing the dynamic scaling, which together describe the scaling behavior in the entire velocity range v ∈[0,∞). These functions have asymptotics corresponding to the adiabatic and diabatic limits, and close to these limits they are perturbative in v and 1/v, respectively. Away from their perturbative domains, both functions cross over into the same universal power-law scaling form governed by the static and dynamic critical exponents (as well as an exponent characterizing the quench protocol). As a by-product of the scaling studies, we obtain high-precision estimates of the dynamic exponent z for the two-dimensional Ising model subject to the three variants of Monte Carlo dynamics: for single-spin Metropolis updates zM=2.1767(5), for Swendsen-Wang multicluster updates zSW=0.297(3), and for Wolff single-cluster updates zW=0.30(2). For Wolff dynamics, we find an interesting behavior with a nonanalytic breakdown of the quasiadiabatic and diabatic scalings, instead of the generic smooth crossover described by a power law. We interpret this disconnect between the two scaling regimes as a dynamic phase transition of the Wolff algorithm, caused by an effective sudden loss of ergodicity at high velocity.
Interpersonal trust: An age-period-cohort analysis revisited.
Clark, April K; Eisenstein, Marie A
2013-03-01
Building on the previous work of Robinson and Jackson(1), this study addresses the extent to which interpersonal trust in America is changing due to age, period, or cohort effects (APC). The importance of APC in explaining variations in trust stems from the understanding that the specific source of change can have important - albeit different and possibly, negative - consequences on society. Moreover, 3years after the previous study concluded, the country experienced the largest concerted terrorist attacks on US soil. Little is known about how the attacks affected the dynamics of interpersonal trust relative to the processes of birth, aging, and historical change - such an investigation has important implications for our understanding of the sources and consequences of interpersonal trust. Two analysis techniques for disentangling APC effects are used: constrained generalized linear models and intrinsic estimator models. The results show that while period effects are an important contributor to declining trust, the attacks exert little influence over one's decision to trust others. Also, the investigation provides further confirmation that trust in others has fallen dramatically in the US with the scarcity being led by individuals coming of age in the late 1940s, after which, trust falls with each successive cohort. If this trend continues, through the process of cohort replacement, we will become a society of "distrusters".
Laban Movement Analysis Approach to Classical Ballet Pedagogy
ERIC Educational Resources Information Center
Whittier, Cadence
2006-01-01
As a Certified Laban Movement Analyst and a classically trained ballet dancer, I consistently weave the Laban Movement Analysis/Bartenieff Fundamentals (LMA/BF) theories and philosophies into the ballet class. This integration assists in: (1) Identifying the qualitative movement elements both in the art of ballet and in the students' dancing…
Laban Movement Analysis Approach to Classical Ballet Pedagogy
ERIC Educational Resources Information Center
Whittier, Cadence
2006-01-01
As a Certified Laban Movement Analyst and a classically trained ballet dancer, I consistently weave the Laban Movement Analysis/Bartenieff Fundamentals (LMA/BF) theories and philosophies into the ballet class. This integration assists in: (1) Identifying the qualitative movement elements both in the art of ballet and in the students' dancing…
A Synthetic Approach to the Transfer Matrix Method in Classical and Quantum Physics
ERIC Educational Resources Information Center
Pujol, O.; Perez, J. P.
2007-01-01
The aim of this paper is to propose a synthetic approach to the transfer matrix method in classical and quantum physics. This method is an efficient tool to deal with complicated physical systems of practical importance in geometrical light or charged particle optics, classical electronics, mechanics, electromagnetics and quantum physics. Teaching…
A Synthetic Approach to the Transfer Matrix Method in Classical and Quantum Physics
ERIC Educational Resources Information Center
Pujol, O.; Perez, J. P.
2007-01-01
The aim of this paper is to propose a synthetic approach to the transfer matrix method in classical and quantum physics. This method is an efficient tool to deal with complicated physical systems of practical importance in geometrical light or charged particle optics, classical electronics, mechanics, electromagnetics and quantum physics. Teaching…
Complex network approach to classifying classical piano compositions
NASA Astrophysics Data System (ADS)
Xin, Chen; Zhang, Huishu; Huang, Jiping
2016-10-01
Complex network has been regarded as a useful tool handling systems with vague interactions. Hence, numerous applications have arised. In this paper we construct complex networks for 770 classical piano compositions of Mozart, Beethoven and Chopin based on musical note pitches and lengths. We find prominent distinctions among network edges of different composers. Some stylized facts can be explained by such parameters of network structures and topologies. Further, we propose two classification methods for music styles and genres according to the discovered distinctions. These methods are easy to implement and the results are sound. This work suggests that complex network could be a decent way to analyze the characteristics of musical notes, since it could provide a deep view into understanding of the relationships among notes in musical compositions and evidence for classification of different composers, styles and genres of music.
Guanidines: from classical approaches to efficient catalytic syntheses.
Alonso-Moreno, Carlos; Antiñolo, Antonio; Carrillo-Hermosilla, Fernando; Otero, Antonio
2014-05-21
From organosuperbases capable of base-catalyzing organic reactions, through versatile 'ligand-sets' for use in coordination chemistry, to fundamental entities in medicinal chemistry, guanidines are amongst the most interesting, attractive, valuable, and versatile organic molecules. Since the discovery of these compounds, synthetic chemists have developed new methodologies that are mainly based on multi-step and stoichiometric reactions. Despite the fact that these methodologies are still being used by the interested scientific and industrial communities, drawbacks such as the poor availability of precursors, low yields, and use and production of undesirable substances highlight the need for safe, simple and efficient syntheses of these entities. This review focuses on the metal-mediated catalytic addition of amines to carbodiimides as an atom-economical alternative to the classical synthesis.
Comparison of Classical and Lazy Approach in SCG Compiler
NASA Astrophysics Data System (ADS)
Jirák, Ota; Kolář, Dušan
2011-09-01
The existing parsing methods of scattered context grammar usually expand nonterminals deeply in the pushdown. This expansion is implemented by using either a linked list, or some kind of an auxiliary pushdown. This paper describes the parsing algorithm of an LL(1) scattered context grammar. The given algorithm merges two principles together. The first approach is a table-driven parsing method commonly used for parsing of the context-free grammars. The second is a delayed execution used in functional programming. The main part of this paper is a proof of equivalence between the common principle (the whole rule is applied at once) and our approach (execution of the rules is delayed). Therefore, this approach works with the pushdown top only. In the most cases, the second approach is faster than the first one. Finally, the future work is discussed.
Cleaning graphene: A first quantum/classical molecular dynamics approach
Delfour, L.; Magaud, L. E-mail: laurence.magaud@grenoble.cnrs.fr
2016-03-28
Graphene outstanding properties created a huge interest in the condensed matter community and unprecedented fundings at the international scale in the hope of application developments. Recently, there have been several reports of incomplete removal of the polymer resists used to transfer as-grown graphene from one substrate to another, resulting in altered graphene transport properties. Finding a large-scale solution to clean graphene from adsorbed residues is highly desirable and one promising possibility would be to use hydrogen plasmas. In this spirit, we couple here quantum and classical molecular dynamics simulations to explore the kinetic energy ranges required by atomic hydrogen to selectively etch a simple residue—a CH{sub 3} group—without irreversibly damaging the graphene. For incident energies in the 2–15 eV range, the CH{sub 3} radical can be etched by forming a volatile CH{sub 4} compound which leaves the surface, either in the CH{sub 4} form or breaking into CH{sub 3} + H fragments, without further defect formation. At this energy, adsorption of H atoms on graphene is possible and further annealing will be required to recover pristine graphene.
Cleaning graphene: A first quantum/classical molecular dynamics approach
NASA Astrophysics Data System (ADS)
Delfour, L.; Davydova, A.; Despiau-Pujo, E.; Cunge, G.; Graves, D. B.; Magaud, L.
2016-03-01
Graphene outstanding properties created a huge interest in the condensed matter community and unprecedented fundings at the international scale in the hope of application developments. Recently, there have been several reports of incomplete removal of the polymer resists used to transfer as-grown graphene from one substrate to another, resulting in altered graphene transport properties. Finding a large-scale solution to clean graphene from adsorbed residues is highly desirable and one promising possibility would be to use hydrogen plasmas. In this spirit, we couple here quantum and classical molecular dynamics simulations to explore the kinetic energy ranges required by atomic hydrogen to selectively etch a simple residue—a CH3 group—without irreversibly damaging the graphene. For incident energies in the 2-15 eV range, the CH3 radical can be etched by forming a volatile CH4 compound which leaves the surface, either in the CH4 form or breaking into CH3 + H fragments, without further defect formation. At this energy, adsorption of H atoms on graphene is possible and further annealing will be required to recover pristine graphene.
Sum Rules, Classical and Quantum - A Pedagogical Approach
NASA Astrophysics Data System (ADS)
Karstens, William; Smith, David Y.
2014-03-01
Sum rules in the form of integrals over the response of a system to an external probe provide general analytical tools for both experiment and theory. For example, the celebrated f-sum rule gives a system's plasma frequency as an integral over the optical-dipole absorption spectrum regardless of the specific spectral distribution. Moreover, this rule underlies Smakula's equation for the number density of absorbers in a sample in terms of the area under their absorption bands. Commonly such rules are derived from quantum-mechanical commutation relations, but many are fundamentally classical (independent of ℏ) and so can be derived from more transparent mechanical models. We have exploited this to illustrate the fundamental role of inertia in the case of optical sum rules. Similar considerations apply to sum rules in many other branches of physics. Thus, the ``attenuation integral theorems'' of ac circuit theory reflect the ``inertial'' effect of Lenz's Law in inductors or the potential energy ``storage'' in capacitors. These considerations are closely related to the fact that the real and imaginary parts of a response function cannot be specified independently, a result that is encapsulated in the Kramers-Kronig relations. Supported in part by the US Department of Energy, Office of Nuclear Physics under contract DE-AC02-06CH11357.
Classic and contemporary approaches to modeling biochemical reactions
Chen, William W.; Niepel, Mario; Sorger, Peter K.
2010-01-01
Recent interest in modeling biochemical networks raises questions about the relationship between often complex mathematical models and familiar arithmetic concepts from classical enzymology, and also about connections between modeling and experimental data. This review addresses both topics by familiarizing readers with key concepts (and terminology) in the construction, validation, and application of deterministic biochemical models, with particular emphasis on a simple enzyme-catalyzed reaction. Networks of coupled ordinary differential equations (ODEs) are the natural language for describing enzyme kinetics in a mass action approximation. We illustrate this point by showing how the familiar Briggs-Haldane formulation of Michaelis-Menten kinetics derives from the outer (or quasi-steady-state) solution of a dynamical system of ODEs describing a simple reaction under special conditions. We discuss how parameters in the Michaelis-Menten approximation and in the underlying ODE network can be estimated from experimental data, with a special emphasis on the origins of uncertainty. Finally, we extrapolate from a simple reaction to complex models of multiprotein biochemical networks. The concepts described in this review, hitherto of interest primarily to practitioners, are likely to become important for a much broader community of cellular and molecular biologists attempting to understand the promise and challenges of “systems biology” as applied to biochemical mechanisms. PMID:20810646
A biplex approach to PageRank centrality: From classic to multiplex networks.
Pedroche, Francisco; Romance, Miguel; Criado, Regino
2016-06-01
In this paper, we present a new view of the PageRank algorithm inspired by multiplex networks. This new approach allows to introduce a new centrality measure for classic complex networks and a new proposal to extend the usual PageRank algorithm to multiplex networks. We give some analytical relations between these new approaches and the classic PageRank centrality measure, and we illustrate the new parameters presented by computing them on real underground networks.
Schmelzer, Jürn W P; Boltachev, Grey Sh; Baidakov, Vladimir G
2006-05-21
In the theoretical interpretation of the kinetics of first-order phase transitions, thermodynamic concepts developed long ago by Gibbs are widely employed giving some basic qualitative insights into these processes. However, from a quantitative point of view, the results of such analysis, based on the classical Gibbs approach and involving in addition the capillarity approximation, are often not satisfactory. Some progress can be reached here by the van der Waals and more advanced density functional methods of description of thermodynamically heterogeneous systems having, however, its limitations in application to the interpretation of experimental data as well. Moreover, both mentioned theories--Gibbs' and density functional approaches--lead to partly contradicting each other's results. As shown in preceding papers, by generalizing Gibbs' approach, existing deficiencies and internal contradictions of these two well-established theories can be removed and a new generally applicable tool for the interpretation of phase formation processes can be developed. In the present analysis, a comparative analysis of the basic assumptions and predictions of the classical and the generalized Gibbs approaches is given. It is shown, in particular, that--interpreted in terms of the generalized Gibbs approach--the critical cluster as determined via the classical Gibbs approach corresponds not to a saddle but to a ridge point of the appropriate thermodynamic potential hypersurface. By this reason, the classical Gibbs approach (involving the classical capillarity approximation) overestimates as a rule the work of critical cluster formation in nucleation theory and, in general, considerably.
A classical approach to the graph isomorphism problem using quantum walks
NASA Astrophysics Data System (ADS)
Douglas, Brendan L.; Wang, Jingbo B.
2008-02-01
Given the extensive application of classical random walks to classical algorithms in a variety of fields, their quantum analogue in quantum walks is expected to provide a fruitful source of quantum algorithms. So far, however, such algorithms have been scarce. In this work, we enumerate some important differences between quantum and classical walks, leading to their markedly different properties. We show that for many practical purposes, the implementation of quantum walks can be efficiently achieved using a classical computer. We then develop both classical and quantum graph isomorphism algorithms based on discrete-time quantum walks. We show that they are effective in identifying isomorphism classes of large databases of graphs, in particular groups of strongly regular graphs. We consider this approach to represent a promising candidate for an efficient solution to the graph isomorphism problem, and believe that similar methods employing quantum walks, or derivatives of these walks, may prove beneficial in constructing other algorithms for a variety of purposes.
General approach to quantum-classical hybrid systems and geometric forces.
Zhang, Qi; Wu, Biao
2006-11-10
We present a general theoretical framework for a hybrid system that is composed of a quantum subsystem and a classical subsystem. We approach such a system with a simple canonical transformation which is particularly effective when the quantum subsystem is dynamically much faster than the classical counterpart, which is commonly the case in hybrid systems. Moreover, this canonical transformation generates a vector potential which, on one hand, gives rise to the familiar Berry phase in the fast quantum dynamics and, on the other hand, yields a Lorentz-like geometric force in the slow classical dynamics.
Tensor renormalization group approach to two-dimensional classical lattice models.
Levin, Michael; Nave, Cody P
2007-09-21
We describe a simple real space renormalization group technique for two-dimensional classical lattice models. The approach is similar in spirit to block spin methods, but at the same time it is fundamentally based on the theory of quantum entanglement. In this sense, the technique can be thought of as a classical analogue of the density matrix renormalization group method. We demonstrate the method - which we call the tensor renormalization group method - by computing the magnetization of the triangular lattice Ising model.
1982-05-15
Data MM—*0 REPORT DOCUMENTATION PAGE f REPORT NUMBER T-465 a. OOVT ACCESSION NO 4. TITLE Cnd SuMlla) CLASSICAL AND BAYSIAN APPROACHES TO...IS. KEY WOROS (Contlmtm on nr«H •!*• II nxmmmmr mit immMr *r NMt • CHANGE POINT, BAYSIAN SEQUENTIAL DETECTION, SURVEY PAPER SO. ABSTRACT
Approaches to Leadership: Some Classic Examples and Recent Theory for Experiential Educators.
ERIC Educational Resources Information Center
Robinson, Tom
Using three classic heroes of literature to examine different approaches to leadership, this paper describes the leadership style of each character and then describes a modern counterpart to each style; each of the modern leaders is an educator and facilitator of experiential learning. Cervantes' Don Quixote ("Don Quixote") is used as an example…
Jumbo-Lucioni, Patricia P.; Garber, Kathryn; Kiel, John; Baric, Ivo; Berry, Gerard T.; Bosch, Annet; Burlina, Alberto; Chiesa, Ana; Pico, Maria Luz Couce; Estrada, Sylvia C.; Henderson, Howard; Leslie, Nancy; Longo, Nicola; Morris, Andrew A. M.; Ramirez-Farias, Carlett; Schweitzer-Krantz, Susanne; Silao, Catherine Lynn T.; Vela-Amieva, Marcela; Waisbren, Susan; Fridovich-Keil, Judith L.
2013-01-01
Without intervention, classic galactosemia is a potentially fatal disorder in infancy. With the benefit of early diagnosis and dietary restriction of galactose, the acute sequelae of classic galactosemia can be prevented or reversed. However, despite early and lifelong dietary treatment, many galactosemic patients go on to experience serious long-term complications including cognitive disability, speech problems, neurological and/or movement disorders and, in girls and women, ovarian dysfunction. Further, there remains uncertainty surrounding what constitutes a ‘best practice’ for treating this disorder. To explore the extent and implications of this uncertainty, we conducted a small but global survey of healthcare providers who follow patients with classic galactosemia, seeking to compare established protocols for diagnosis, intervention, and follow-up, as well as the outcomes and outcome frequencies seen in the patient populations cared for by these providers. We received 13 survey responses representing five continents and 11 countries. Respondents underscored disparities in approaches to diagnosis, management and follow-up care. Notably, we saw no clear relationship between differing approaches to care and long-term outcomes in the populations studied. Negative outcomes occurred in the majority of cases regardless of when treatment was initiated, how tightly galactose intake was restricted, or how closely patients were monitored. We document here what is, to our knowledge, the first global comparison of healthcare approaches to classic galactosemia. These data reinforce the idea that there is currently no one best practice for treating patients with classic galactosemia, and underscore the need for more extensive and statistically powerful comparative studies to reveal potential positive or negative impacts of differing approaches. PMID:22450714
Jumbo-Lucioni, Patricia P; Garber, Kathryn; Kiel, John; Baric, Ivo; Berry, Gerard T; Bosch, Annet; Burlina, Alberto; Chiesa, Ana; Pico, Maria Luz Couce; Estrada, Sylvia C; Henderson, Howard; Leslie, Nancy; Longo, Nicola; Morris, Andrew A M; Ramirez-Farias, Carlett; Schweitzer-Krantz, Susanne; Scheweitzer-Krantz, Susanne; Silao, Catherine Lynn T; Vela-Amieva, Marcela; Waisbren, Susan; Fridovich-Keil, Judith L
2012-11-01
Without intervention, classic galactosemia is a potentially fatal disorder in infancy. With the benefit of early diagnosis and dietary restriction of galactose, the acute sequelae of classic galactosemia can be prevented or reversed. However, despite early and lifelong dietary treatment, many galactosemic patients go on to experience serious long-term complications including cognitive disability, speech problems, neurological and/or movement disorders and, in girls and women, ovarian dysfunction. Further, there remains uncertainty surrounding what constitutes a 'best practice' for treating this disorder. To explore the extent and implications of this uncertainty, we conducted a small but global survey of healthcare providers who follow patients with classic galactosemia, seeking to compare established protocols for diagnosis, intervention, and follow-up, as well as the outcomes and outcome frequencies seen in the patient populations cared for by these providers. We received 13 survey responses representing five continents and 11 countries. Respondents underscored disparities in approaches to diagnosis, management and follow-up care. Notably, we saw no clear relationship between differing approaches to care and long-term outcomes in the populations studied. Negative outcomes occurred in the majority of cases regardless of when treatment was initiated, how tightly galactose intake was restricted, or how closely patients were monitored. We document here what is, to our knowledge, the first global comparison of healthcare approaches to classic galactosemia. These data reinforce the idea that there is currently no one best practice for treating patients with classic galactosemia, and underscore the need for more extensive and statistically powerful comparative studies to reveal potential positive or negative impacts of differing approaches.
Wang, Qian; Hammes-Schiffer, Sharon
2006-11-14
A hybrid quantum/classical path integral Monte Carlo (QC-PIMC) method for calculating the quantum free energy barrier for hydrogen transfer reactions in condensed phases is presented. In this approach, the classical potential of mean force along a collective reaction coordinate is calculated using umbrella sampling techniques in conjunction with molecular dynamics trajectories propagated according to a mapping potential. The quantum contribution is determined for each configuration along the classical trajectory with path integral Monte Carlo calculations in which the beads move according to an effective mapping potential. This type of path integral calculation does not utilize the centroid constraint and can lead to more efficient sampling of the relevant region of conformational space than free-particle path integral sampling. The QC-PIMC method is computationally practical for large systems because the path integral sampling for the quantum nuclei is performed separately from the classical molecular dynamics sampling of the entire system. The utility of the QC-PIMC method is illustrated by an application to hydride transfer in the enzyme dihydrofolate reductase. A comparison of this method to the quantized classical path and grid-based methods for this system is presented.
Kandaswamy, Krishna Kumar; Pugalenthi, Ganesan; Hartmann, Enno; Kalies, Kai-Uwe; Moeller, Steffen; Suganthan, P.N.; Martinetz, Thomas
2010-01-15
Eukaryotic protein secretion generally occurs via the classical secretory pathway that traverses the ER and Golgi apparatus. Secreted proteins usually contain a signal sequence with all the essential information required to target them for secretion. However, some proteins like fibroblast growth factors (FGF-1, FGF-2), interleukins (IL-1 alpha, IL-1 beta), galectins and thioredoxin are exported by an alternative pathway. This is known as leaderless or non-classical secretion and works without a signal sequence. Most computational methods for the identification of secretory proteins use the signal peptide as indicator and are therefore not able to identify substrates of non-classical secretion. In this work, we report a random forest method, SPRED, to identify secretory proteins from protein sequences irrespective of N-terminal signal peptides, thus allowing also correct classification of non-classical secretory proteins. Training was performed on a dataset containing 600 extracellular proteins and 600 cytoplasmic and/or nuclear proteins. The algorithm was tested on 180 extracellular proteins and 1380 cytoplasmic and/or nuclear proteins. We obtained 85.92% accuracy from training and 82.18% accuracy from testing. Since SPRED does not use N-terminal signals, it can detect non-classical secreted proteins by filtering those secreted proteins with an N-terminal signal by using SignalP. SPRED predicted 15 out of 19 experimentally verified non-classical secretory proteins. By scanning the entire human proteome we identified 566 protein sequences potentially undergoing non-classical secretion. The dataset and standalone version of the SPRED software is available at (http://www.inb.uni-luebeck.de/tools-demos/spred/spred).
Semenov, Alexander; Babikov, Dmitri
2015-05-21
An efficient and accurate mixed quantum/classical theory approach for computational treatment of inelastic scattering is extended to describe collision of an atom with a general asymmetric-top rotor polyatomic molecule. Quantum mechanics, employed to describe transitions between the internal states of the molecule, and classical mechanics, employed for description of scattering of the atom, are used in a self-consistent manner. Such calculations for rotational excitation of HCOOCH3 in collisions with He produce accurate results at scattering energies above 15 cm(-1), although resonances near threshold, below 5 cm(-1), cannot be reproduced. Importantly, the method remains computationally affordable at high scattering energies (here up to 1000 cm(-1)), which enables calculations for larger molecules and at higher collision energies than was possible previously with the standard full-quantum approach. Theoretical prediction of inelastic cross sections for a number of complex organic molecules observed in space becomes feasible using this new computational tool.
Shakib, Farnaz; Hanna, Gabriel
2016-07-12
In this work, we derive a general mixed quantum-classical formula for calculating thermal proton-coupled electron-transfer (PCET) rate constants, starting from the time integral of the quantum flux-flux correlation function. This formula allows for the direct simulation of PCET reaction dynamics via the mixed quantum-classical Liouville approach. Owing to the general nature of the derivation, this formula does not rely on any prior mechanistic assumptions and can be applied across a wide range of electronic and protonic coupling regimes. To test the validity of this formula, we applied it to a reduced model of a condensed-phase PCET reaction. Good agreement with the numerically exact rate constant is obtained, demonstrating the accuracy of our formalism. We believe that this approach constitutes a solid foundation for future investigations of the rates and mechanisms of a wide range of PCET reactions.
Approaches to define the viral genetic basis of classical swine fever virus virulence.
Leifer, Immanuel; Ruggli, Nicolas; Blome, Sandra
2013-04-10
Classical swine fever (CSF), a highly contagious disease of pigs caused by the classical swine fever virus (CSFV), can lead to important economic losses in the pig industry. Numerous CSFV isolates with various degrees of virulence have been isolated worldwide, ranging from low virulent strains that do not result in any apparent clinical signs to highly virulent strains that cause a severe peracute hemorrhagic fever with nearly 100% mortality. Knowledge of the molecular determinants of CSFV virulence is an important issue for effective disease control and development of safe and effective marker vaccines. In this review, the latest studies in the field of CSFV virulence are discussed. The topic of virulence is addressed from different angles; nonconventional approaches like codon pair usage and quasispecies are considered. Future research approaches in the field of CSFV virulence are proposed.
Homogeneous nucleation: classical formulas as asymptotic limits of the Cahn-Hilliard approach.
Parra, I E; Cordero-Gracia, M; Gómez, M
2007-02-07
Classical expressions for the critical cluster work of formation approximate the nonclassical expressions based in the density functional theory of capillarity for the limit of low supersaturation degrees. However, the ratio between classical and nonclassical expressions for nucleation rates grows as the supersaturation degree decreases. Here, with the aim to obtain simple and more accurate expressions that approximate the modern nucleation rate formulas, an asymptotic expansion of the Cahn-Hilliard expression of the critical work of formation is developed within the limit of low supersaturation. In such asymptotic expansion, terms up to third order are retained. The ratios between the corrected classical expressions and the nonclassical ones are now decreasing for supersaturation degrees tending to zero. However, the corrected approximate formulas are as difficult to handle as the exact Cahn-Hilliard expressions. When only the two first low-order terms of the asymptotic expansion are retained, a simpler corrected classical expression is obtained but it can only approximate nonclassical expressions up to order unity. Finally, using a Becker-Doring model of nucleation, the kinetic prefactor of the critical nuclei rate of formation is modeled consistently with the Cahn-Hilliard approach to the critical work of formation.
A Monte Carlo Resampling Approach for the Calculation of Hybrid Classical and Quantum Free Energies.
Cave-Ayland, Christopher; Skylaris, Chris-Kriton; Essex, Jonathan W
2017-02-14
Hybrid free energy methods allow estimation of free energy differences at the quantum mechanics (QM) level with high efficiency by performing sampling at the classical mechanics (MM) level. Various approaches to allow the calculation of QM corrections to classical free energies have been proposed. The single step free energy perturbation approach starts with a classically generated ensemble, a subset of structures of which are postprocessed to obtain QM energies for use with the Zwanzig equation. This gives an estimate of the free energy difference associated with the change from an MM to a QM Hamiltonian. Owing to the poor numerical properties of the Zwanzig equation, however, recent developments have produced alternative methods which aim to provide access to the properties of the true QM ensemble. Here we propose an approach based on the resampling of MM structural ensembles and application of a Monte Carlo acceptance test which in principle, can generate the exact QM ensemble or intermediate ensembles between the MM and QM states. We carry out a detailed comparison against the Zwanzig equation and recently proposed non-Boltzmann methods. As a test system we use a set of small molecule hydration free energies for which hybrid free energy calculations are performed at the semiempirical Density Functional Tight Binding level. Equivalent ensembles at this level of theory have also been generated allowing the reverse QM to MM perturbations to be performed along with a detailed analysis of the results. Additionally, a previously published nucleotide base pair data set simulated at the QM level using ab initio molecular dynamics is also considered. We provide a strong rationale for the use of the Monte Carlo Resampling and non-Boltzmann approaches by showing that configuration space overlaps can be estimated which provide useful diagnostic information regarding the accuracy of these hybrid approaches.
Mottin, Stephane; Panasenko, Grigory; Ganesh, S Sivaji
2010-12-31
In biophotonics, the light absorption in a tissue is usually modeled by the Helmholtz equation with two constant parameters, the scattering coefficient and the absorption coefficient. This classic approximation of "haemoglobin diluted everywhere" (constant absorption coefficient) corresponds to the classical homogenization approach. The paper discusses the limitations of this approach. The scattering coefficient is supposed to be constant (equal to one) while the absorption coefficient is equal to zero everywhere except for a periodic set of thin parallel strips simulating the blood vessels, where it is a large parameter ω. The problem contains two other parameters which are small: ε, the ratio of the distance between the axes of vessels to the characteristic macroscopic size, and δ, the ratio of the thickness of thin vessels and the period. We construct asymptotic expansion in two cases: ε --> 0, ω --> ∞, δ --> 0, ωδ --> ∞, ε2ωδ --> 0 and ε --> 0, ω --> ∞, δ --> 0, ε2ωδ --> ∞, and and prove that in the first case the classical homogenization (averaging) of the differential equation is true while in the second case it is wrong. This result may be applied in the biomedical optics, for instance, in the modeling of the skin and cosmetics.
Validity of the semi-classical approach for calculation of the surface excitation parameter.
Da, B; Mao, S F; Ding, Z J
2011-10-05
The problem of surface plasmon excitation by moving charges has been elaborated by several different approaches, mainly based on dielectric response theory within either semi-classical or quantum mechanical frameworks. In this work, a comparison of the surface excitation effect between two different frameworks is made by calculation of the differential inverse inelastic mean free path (DIIMFP) and a Monte Carlo simulation of reflection electron energy loss spectroscopy (REELS) spectra. A semi-classical modeling of the interaction between electrons and a solid surface is based on analyzing the work done by moving electrons; the stopping power and inelastic cross section are derived with the induced potential. On the other hand, a quantum mechanical approach is based on derivation of the complex inhomogeneous self-energy of the electrons. The numerical calculation shows that the semi-classical model presents almost the same values of DIIMFP as by the quantum model except at the glancing condition. The simulation of REELS spectra for Ag and SiO(2) as well as a comparison with experimental spectra also confirms that a good agreement with the spectral shape is found among the two simulation results and the experimental data.
Müller-Putz, G R; Schwarz, A; Pereira, J; Ofner, P
2016-01-01
In this chapter, we give an overview of the Graz-BCI research, from the classic motor imagery detection to complex movement intentions decoding. We start by describing the classic motor imagery approach, its application in tetraplegic end users, and the significant improvements achieved using coadaptive brain-computer interfaces (BCIs). These strategies have the drawback of not mirroring the way one plans a movement. To achieve a more natural control-and to reduce the training time-the movements decoded by the BCI need to be closely related to the user's intention. Within this natural control, we focus on the kinematic level, where movement direction and hand position or velocity can be decoded from noninvasive recordings. First, we review movement execution decoding studies, where we describe the decoding algorithms, their performance, and associated features. Second, we describe the major findings in movement imagination decoding, where we emphasize the importance of estimating the sources of the discriminative features. Third, we introduce movement target decoding, which could allow the determination of the target without knowing the exact movement-by-movement details. Aside from the kinematic level, we also address the goal level, which contains relevant information on the upcoming action. Focusing on hand-object interaction and action context dependency, we discuss the possible impact of some recent neurophysiological findings in the future of BCI control. Ideally, the goal and the kinematic decoding would allow an appropriate matching of the BCI to the end users' needs, overcoming the limitations of the classic motor imagery approach.
[A non-classical approach to medical practices: Michel Foucault and Actor-Network Theory].
Bińczyk, E
2001-01-01
The text presents an analysis of medical practices stemming from two sources: Michel Foucault's conception and the research of Annemarie Mol and John Law, representatives of a trend known as Actor-Network Theory. Both approaches reveal significant theoretical kinship: they can be successfully consigned to the framework of non-classical sociology of science. I initially refer to the cited conceptions as a version of non-classical sociology of medicine. The identity of non-classical sociology of medicine hinges on the fact that it undermines the possibility of objective definitions of disease, health and body. These are rather approached as variable social and historical phenomena, co-constituted by medical practices. To both Foucault and Mol the main object of interest was not medicine as such, but rather the network of medical practices. Mol and Law sketch a new theoretical perspective for the analysis of medical practices. They attempt to go beyond the dichotomous scheme of thinking about the human body as an object of medical research and the subject of private experience. Research on patients suffering blood-sugar deficiency provide the empirical background for the thesis of Actor-Network Theory representatives. Michel Foucault's conceptions are extremely critical of medical practices. The French researcher describes the processes of 'medicalising' Western society as the emergence of a new type of power. He attempts to sensitise the reader to the ethical dimension of the processes of medicalising society.
NASA Technical Reports Server (NTRS)
Yamamoto, Y.; Ando, S.
1987-01-01
The unsteady aerodynamics of a two-dimensional wing at sonic speed are studied by using so-called classical sonic theories (linear), approached from supersonic flow (M=1+0) or subsonic flow (M=1-0). In the former approach, the exact expressions of lift and lift distribution are obtained in terms of Fresnel integrals, while in the latter approach an integral equation must be solved, the kernel function of which is obtained from the subsonic Possio's equation and has a root singularity. The discrete analysis is adopted on the basis of the semicircle method (SCM) and the weighting function for subsonic-flow-Gauss-quadrature, as well as modified characteristics obtained from both approaches agree quite well with each other. The results obtained by the present computations are compared with those of DLM-C (subsonic 2D code) developed by ANDO et al, and are found to give a reasonable outer boundary for subsonic unsteady aerodynamics.
NASA Astrophysics Data System (ADS)
Santos, F. A. N.; da Silva, L. C. B.; Coutinho-Filho, M. D.
2017-01-01
We propose a topological approach suitable to establish a connection between thermodynamics and topology in the microcanonical ensemble. Indeed, we report on results that point to the possibility of describing interacting classical spin systems in the thermodynamic limit, including the occurrence of a phase transition, using topological arguments only. Our approach relies on Morse theory, through the determination of the critical points of the potential energy, which is the proper Morse function. Our main finding is that, in the context of the classical models studied, the Euler characteristic χ (E) embeds the necessary features for a correct description of several magnetic thermodynamic quantities of the systems, such as the magnetization, correlation function, susceptibility, and critical temperature. Despite the classical nature of the models, such quantities are those that do not violate the laws of thermodynamics (with the proviso that van der Waals loop states are mean field (MF) artifacts). We also discuss the subtle connection between our approach using the Euler entropy, defined by the logarithm of the modulus of χ (E) per site, and that using the Boltzmann microcanonical entropy. Moreover, the results suggest that the loss of regularity in the Morse function is associated with the occurrence of unstable and metastable thermodynamic solutions in the MF case. The reliability of our approach is tested in two exactly soluble systems: the infinite-range and the one-dimensional short-range XY models in the presence of a magnetic field. In particular, we confirm that the topological hypothesis holds for both the infinite-range ({{T}c}\
Galitski, Victor
2011-07-15
We propose a Lie-algebraic duality approach to analyze nonequilibrium evolution of closed dynamical systems and thermodynamics of interacting quantum lattice models (formulated in terms of Hubbard-Stratonovich dynamical systems). The first part of the paper utilizes a geometric Hilbert-space-invariant formulation of unitary time evolution, where a quantum Hamiltonian is viewed as a trajectory in an abstract Lie algebra, while the sought-after evolution operator is a trajectory in a dynamic group, generated by the algebra via exponentiation. The evolution operator is uniquely determined by the time-dependent dual generators that satisfy a system of differential equations, dubbed here dual Schroedinger-Bloch equations, which represent a viable alternative to the conventional Schroedinger formulation. These dual Schroedinger-Bloch equations are derived and analyzed on a number of specific examples. It is shown that deterministic dynamics of a closed classical dynamical system occurs as action of a symmetry group on a classical manifold and is driven by the same dual generators as in the corresponding quantum problem. This represents quantum-to-classical correspondence. In the second part of the paper, we further extend the Lie-algebraic approach to a wide class of interacting many-particle lattice models. A generalized Hubbard-Stratonovich transform is proposed and it is used to show that the thermodynamic partition function of a generic many-body quantum lattice model can be expressed in terms of traces of single-particle evolution operators governed by the dynamic Hubbard-Stratonovich fields. The corresponding Hubbard-Stratonovich dynamical systems are generally nonunitary, which yields a number of notable complications, including breakdown of the global exponential representation. Finally, we derive Hubbard-Stratonovich dynamical systems for the Bose-Hubbard model and a quantum spin model and use the Lie-algebraic approach to obtain new nonperturbative dual
ERIC Educational Resources Information Center
Weinbaum, Batya
2004-01-01
In this article, the author describes "Feminist Approaches to the Classics," a course she teaches at Cleveland State University. The goal of this particular course was to situate the context of western indigenous myth in relation to western classical literature and to indicate possible reasons for its reclamation in contemporary American…
ERIC Educational Resources Information Center
National Council of Teachers of English, Urbana, IL.
New approaches to the teaching of the classics are explored in this collection of articles written by high school, junior college, college, and university literature instructors. The seven articles in the first section of the book discuss linking the classics. Specific topics covered in the articles include using the works of William Golding as a…
Treatment of rheumatoid arthritis. New thoughts on the classic pyramid approach.
Schenkier, S; Golbus, J
1992-01-01
Treatment of rheumatoid arthritis can be quite challenging. Toxicity profiles of the various anti-inflammatory agents are often unacceptable, mainly because of gastrointestinal intolerance or bleeding. In addition, epidemiologic data suggest that rheumatoid arthritis is a disease with substantial morbidity and increased mortality. Consequently, newer trends in therapy involve earlier use of remittive agents as well as use of low-dose steroids. These modifications of the classic pyramid approach and the investigation of other methods may significantly influence the future of rheumatoid arthritis therapy and improve quality of life in those with the disease.
NASA Technical Reports Server (NTRS)
Bond, Wie
1991-01-01
The results of active control experiments performed for the Mini-Mast truss structure are presented. The primary research objectives were: (1) to develop active structural control concepts and/or techniques; (2) to verify the concept of robust non-minimum-phase compensation for a certain class of non-colocated structural control problems through ground experiments; (3) to verify a 'dipole' concept for persistent disturbance rejection control of flexible structures; and (4) to identify CSI (Control Structure Interaction) issues and areas of emphasis for the next generation of large flexible spacecraft. The classical SISO (Single Input and Single Output) control design approach was employed.
On the relevance of assumptions associated with classical factor analytic approaches.
Kasper, Daniel; Unlü, Ali
2013-01-01
A personal trait, for example a person's cognitive ability, represents a theoretical concept postulated to explain behavior. Interesting constructs are latent, that is, they cannot be observed. Latent variable modeling constitutes a methodology to deal with hypothetical constructs. Constructs are modeled as random variables and become components of a statistical model. As random variables, they possess a probability distribution in the population of reference. In applications, this distribution is typically assumed to be the normal distribution. The normality assumption may be reasonable in many cases, but there are situations where it cannot be justified. For example, this is true for criterion-referenced tests or for background characteristics of students in large scale assessment studies. Nevertheless, the normal procedures in combination with the classical factor analytic methods are frequently pursued, despite the effects of violating this "implicit" assumption are not clear in general. In a simulation study, we investigate whether classical factor analytic approaches can be instrumental in estimating the factorial structure and properties of the population distribution of a latent personal trait from educational test data, when violations of classical assumptions as the aforementioned are present. The results indicate that having a latent non-normal distribution clearly affects the estimation of the distribution of the factor scores and properties thereof. Thus, when the population distribution of a personal trait is assumed to be non-symmetric, we recommend avoiding those factor analytic approaches for estimation of a person's factor score, even though the number of extracted factors and the estimated loading matrix may not be strongly affected. An application to the Progress in International Reading Literacy Study (PIRLS) is given. Comments on possible implications for the Programme for International Student Assessment (PISA) complete the presentation.
Quantum decoherence of I2 in liquid xenon: a classical Wigner approach.
Elran, Yossi; Brumer, Paul
2013-06-21
Vibrational decoherence of a "breathing sphere" oscillator in a thermal Lennard-Jones bath is examined using a classical analog approach. The equivalence between this approach and the linearized semiclassical initial value representation (IVR) is established and the method is exploited to produce a useful computational strategy that can efficiently evaluate the time dependence of the decoherence in these systems. A comparison between Harmonic and Morse "breathing sphere" models is presented and the rate of decoherence is found to depend on the choice of model, the initial state of the oscillator, the initial conditions of the bath (temperature, density), and the choice of quantity measuring the decoherence rate. The results are used to examine the utility of the Caldeira-Leggett model in this realistic system.
Complementary approaches to diagnosing marine diseases: a union of the modern and the classic.
Burge, Colleen A; Friedman, Carolyn S; Getchell, Rodman; House, Marcia; Lafferty, Kevin D; Mydlarz, Laura D; Prager, Katherine C; Sutherland, Kathryn P; Renault, Tristan; Kiryu, Ikunari; Vega-Thurber, Rebecca
2016-03-05
Linking marine epizootics to a specific aetiology is notoriously difficult. Recent diagnostic successes show that marine disease diagnosis requires both modern, cutting-edge technology (e.g. metagenomics, quantitative real-time PCR) and more classic methods (e.g. transect surveys, histopathology and cell culture). Here, we discuss how this combination of traditional and modern approaches is necessary for rapid and accurate identification of marine diseases, and emphasize how sole reliance on any one technology or technique may lead disease investigations astray. We present diagnostic approaches at different scales, from the macro (environment, community, population and organismal scales) to the micro (tissue, organ, cell and genomic scales). We use disease case studies from a broad range of taxa to illustrate diagnostic successes from combining traditional and modern diagnostic methods. Finally, we recognize the need for increased capacity of centralized databases, networks, data repositories and contingency plans for diagnosis and management of marine disease. © 2016 The Author(s).
Modeling of delays in PKPD: classical approaches and a tutorial for delay differential equations.
Koch, Gilbert; Krzyzanski, Wojciech; Pérez-Ruixo, Juan Jose; Schropp, Johannes
2014-08-01
In pharmacokinetics/pharmacodynamics (PKPD) the measured response is often delayed relative to drug administration, individuals in a population have a certain lifespan until they maturate or the change of biomarkers does not immediately affects the primary endpoint. The classical approach in PKPD is to apply transit compartment models (TCM) based on ordinary differential equations to handle such delays. However, an alternative approach to deal with delays are delay differential equations (DDE). DDEs feature additional flexibility and properties, realize more complex dynamics and can complementary be used together with TCMs. We introduce several delay based PKPD models and investigate mathematical properties of general DDE based models, which serve as subunits in order to build larger PKPD models. Finally, we review current PKPD software with respect to the implementation of DDEs for PKPD analysis.
Complementary approaches to diagnosing marine diseases: a union of the modern and the classic
Burge, Colleen A.; Friedman, Carolyn S.; Getchell, Rodman G.; House, Marcia; Lafferty, Kevin D.; Mydlarz, Laura D.; Prager, Katherine C.; Sutherland, Kathryn P.; Renault, Tristan; Kiryu, Ikunari; Vega-Thurber, Rebecca
2016-01-01
Linking marine epizootics to a specific aetiology is notoriously difficult. Recent diagnostic successes show that marine disease diagnosis requires both modern, cutting-edge technology (e.g. metagenomics, quantitative real-time PCR) and more classic methods (e.g. transect surveys, histopathology and cell culture). Here, we discuss how this combination of traditional and modern approaches is necessary for rapid and accurate identification of marine diseases, and emphasize how sole reliance on any one technology or technique may lead disease investigations astray. We present diagnostic approaches at different scales, from the macro (environment, community, population and organismal scales) to the micro (tissue, organ, cell and genomic scales). We use disease case studies from a broad range of taxa to illustrate diagnostic successes from combining traditional and modern diagnostic methods. Finally, we recognize the need for increased capacity of centralized databases, networks, data repositories and contingency plans for diagnosis and management of marine disease.
Complementary approaches to diagnosing marine diseases: a union of the modern and the classic
Burge, Colleen A.; Friedman, Carolyn S.; Getchell, Rodman; House, Marcia; Mydlarz, Laura D.; Prager, Katherine C.; Renault, Tristan; Kiryu, Ikunari; Vega-Thurber, Rebecca
2016-01-01
Linking marine epizootics to a specific aetiology is notoriously difficult. Recent diagnostic successes show that marine disease diagnosis requires both modern, cutting-edge technology (e.g. metagenomics, quantitative real-time PCR) and more classic methods (e.g. transect surveys, histopathology and cell culture). Here, we discuss how this combination of traditional and modern approaches is necessary for rapid and accurate identification of marine diseases, and emphasize how sole reliance on any one technology or technique may lead disease investigations astray. We present diagnostic approaches at different scales, from the macro (environment, community, population and organismal scales) to the micro (tissue, organ, cell and genomic scales). We use disease case studies from a broad range of taxa to illustrate diagnostic successes from combining traditional and modern diagnostic methods. Finally, we recognize the need for increased capacity of centralized databases, networks, data repositories and contingency plans for diagnosis and management of marine disease. PMID:26880839
NASA Astrophysics Data System (ADS)
Alam, Muhammad Ashraful; Khan, M. Ryyan
2016-10-01
Bifacial tandem cells promise to reduce three fundamental losses (i.e., above-bandgap, below bandgap, and the uncollected light between panels) inherent in classical single junction photovoltaic (PV) systems. The successive filtering of light through the bandgap cascade and the requirement of current continuity make optimization of tandem cells difficult and accessible only to numerical solution through computer modeling. The challenge is even more complicated for bifacial design. In this paper, we use an elegantly simple analytical approach to show that the essential physics of optimization is intuitively obvious, and deeply insightful results can be obtained with a few lines of algebra. This powerful approach reproduces, as special cases, all of the known results of conventional and bifacial tandem cells and highlights the asymptotic efficiency gain of these technologies.
Onisko, Agnieszka; Druzdzel, Marek J; Austin, R Marshall
2016-01-01
Classical statistics is a well-established approach in the analysis of medical data. While the medical community seems to be familiar with the concept of a statistical analysis and its interpretation, the Bayesian approach, argued by many of its proponents to be superior to the classical frequentist approach, is still not well-recognized in the analysis of medical data. The goal of this study is to encourage data analysts to use the Bayesian approach, such as modeling with graphical probabilistic networks, as an insightful alternative to classical statistical analysis of medical data. This paper offers a comparison of two approaches to analysis of medical time series data: (1) classical statistical approach, such as the Kaplan-Meier estimator and the Cox proportional hazards regression model, and (2) dynamic Bayesian network modeling. Our comparison is based on time series cervical cancer screening data collected at Magee-Womens Hospital, University of Pittsburgh Medical Center over 10 years. The main outcomes of our comparison are cervical cancer risk assessments produced by the three approaches. However, our analysis discusses also several aspects of the comparison, such as modeling assumptions, model building, dealing with incomplete data, individualized risk assessment, results interpretation, and model validation. Our study shows that the Bayesian approach is (1) much more flexible in terms of modeling effort, and (2) it offers an individualized risk assessment, which is more cumbersome for classical statistical approaches.
Onisko, Agnieszka; Druzdzel, Marek J.; Austin, R. Marshall
2016-01-01
Background: Classical statistics is a well-established approach in the analysis of medical data. While the medical community seems to be familiar with the concept of a statistical analysis and its interpretation, the Bayesian approach, argued by many of its proponents to be superior to the classical frequentist approach, is still not well-recognized in the analysis of medical data. Aim: The goal of this study is to encourage data analysts to use the Bayesian approach, such as modeling with graphical probabilistic networks, as an insightful alternative to classical statistical analysis of medical data. Materials and Methods: This paper offers a comparison of two approaches to analysis of medical time series data: (1) classical statistical approach, such as the Kaplan–Meier estimator and the Cox proportional hazards regression model, and (2) dynamic Bayesian network modeling. Our comparison is based on time series cervical cancer screening data collected at Magee-Womens Hospital, University of Pittsburgh Medical Center over 10 years. Results: The main outcomes of our comparison are cervical cancer risk assessments produced by the three approaches. However, our analysis discusses also several aspects of the comparison, such as modeling assumptions, model building, dealing with incomplete data, individualized risk assessment, results interpretation, and model validation. Conclusion: Our study shows that the Bayesian approach is (1) much more flexible in terms of modeling effort, and (2) it offers an individualized risk assessment, which is more cumbersome for classical statistical approaches. PMID:28163973
Filtering schemes in the quantum-classical Liouville approach to nonadiabatic dynamics.
Uken, Daniel A; Sergi, Alessandro; Petruccione, Francesco
2013-09-01
We study a number of filtering schemes for the reduction of the statistical error in nonadiabatic calculations by means of the quantum-classical Liouville equation. In particular, we focus on a scheme based on setting a threshold value on the sampling weights, so that when the threshold is overcome the value of the weight is reset, and on another approach which prunes the ensemble of the allowed nonadiabatic transitions according to a generalized sampling probability. Both methods have advantages and drawbacks, however, their combination drastically improves the performance of an algorithm known as the sequential short-time step propagation [MacKernan et al., J. Phys: Condens. Matter 14, 9069 (2002)], which is derived from a simple first order expansion of the quantum-classical propagator. Such an algorithm together with the combined filtering procedures produce results that compare very well with those obtained by means of numerically accurate path integral quantum calculations for the spin-boson model, even for intermediate and strong coupling regimes.
Numerical study of chiral plasma instability within the classical statistical field theory approach
NASA Astrophysics Data System (ADS)
Buividovich, P. V.; Ulybyshev, M. V.
2016-07-01
We report on a numerical study of real-time dynamics of electromagnetically interacting chirally imbalanced lattice Dirac fermions within the classical statistical field theory approach. Namely, we perform exact simulations of the real-time quantum evolution of fermionic fields coupled to classical electromagnetic fields, which are in turn coupled to the vacuum expectation value of the fermionic electric current. We use Wilson-Dirac Hamiltonian for fermions, and noncompact action for the gauge field. In general, we observe that the backreaction of fermions on the electromagnetic field prevents the system from acquiring chirality imbalance. In the case of chirality pumping in parallel electric and magnetic fields, the electric field is screened by the produced on-shell fermions and the accumulation of chirality is hence stopped. In the case of evolution with initially present chirality imbalance, axial charge tends to transform to helicity of the electromagnetic field. By performing simulations on large lattices we show that in most cases this decay process is accompanied by the inverse cascade phenomenon, which transfers energy from short-wavelength to long-wavelength electromagnetic fields. In some simulations, however, we observe a very clear signature of inverse cascade for the helical magnetic fields that is not accompanied by the axial charge decay. This suggests that the relation between the inverse cascade and axial charge decay is not as straightforward as predicted by the simplest form of anomalous Maxwell equations.
Non-Kolmogorovian Approach to the Context-Dependent Systems Breaking the Classical Probability Law
NASA Astrophysics Data System (ADS)
Asano, Masanari; Basieva, Irina; Khrennikov, Andrei; Ohya, Masanori; Yamato, Ichiro
2013-07-01
There exist several phenomena breaking the classical probability laws. The systems related to such phenomena are context-dependent, so that they are adaptive to other systems. In this paper, we present a new mathematical formalism to compute the joint probability distribution for two event-systems by using concepts of the adaptive dynamics and quantum information theory, e.g., quantum channels and liftings. In physics the basic example of the context-dependent phenomena is the famous double-slit experiment. Recently similar examples have been found in biological and psychological sciences. Our approach is an extension of traditional quantum probability theory, and it is general enough to describe aforementioned contextual phenomena outside of quantum physics.
NASA Astrophysics Data System (ADS)
Appelhans, Tim; Mwangomo, Ephraim; Otte, Insa; Detsch, Florian; Nauss, Thomas; Hemp, Andreas; Ndyamkama, Jimmy
2015-04-01
This study introduces the set-up and characteristics of a meteorological station network on the southern slopes of Mt. Kilimanjaro, Tanzania. The set-up follows a hierarchical approach covering an elevational as well as a land-use disturbance gradient. The network consists of 52 basic stations measuring ambient air temperature and above ground air humidity and 11 precipitation measurement sites. We provide in depth descriptions of various machine learning and classical geo-statistical methods used to fill observation gaps and extend the spatial coverage of the network to a total of 60 research sites. Performance statistics for these methods indicate that the presented data sets provide reliable measurements of the meteorological reality at Mt. Kilimanjaro. These data provide an excellent basis for ecological studies and are also of great value for regional atmospheric numerical modelling studies for which such comprehensive in-situ validation observations are rare, especially in tropical regions of complex terrain.
Lee, Sang-Bong
1993-09-01
Quantum manifestation of classical chaos has been one of the extensively studied subjects for more than a decade. Yet clear understanding of its nature still remains to be an open question partly due to the lack of a canonical definition of quantum chaos. The classical definition seems to be unsuitable in quantum mechanics partly because of the Heisenberg quantum uncertainty. In this regard, quantum chaos is somewhat misleading and needs to be clarified at the very fundamental level of physics. Since it is well known that quantum mechanics is more fundamental than classical mechanics, the quantum description of classically chaotic nature should be attainable in the limit of large quantum numbers. The focus of my research, therefore, lies on the correspondence principle for classically chaotic systems. The chaotic damped driven pendulum is mainly studied numerically using the split operator method that solves the time-dependent Schroedinger equation. For classically dissipative chaotic systems in which (multi)fractal strange attractors often emerge, several quantum dissipative mechanisms are also considered. For instance, Hoover`s and Kubo-Fox-Keizer`s approaches are studied with some computational analyses. But the notion of complex energy with non-Hermiticity is extensively applied. Moreover, the Wigner and Husimi distribution functions are examined with an equivalent classical distribution in phase-space, and dynamical properties of the wave packet in configuration and momentum spaces are also explored. The results indicate that quantum dynamics embraces classical dynamics although the classicalquantum correspondence fails to be observed in the classically chaotic regime. Even in the semi-classical limits, classically chaotic phenomena would eventually be suppressed by the quantum uncertainty.
Path-integral approach to 't Hooft's derivation of quantum physics from classical physics
Blasone, Massimo; Jizba, Petr; Kleinert, Hagen
2005-05-15
We present a path-integral formulation of 't Hooft's derivation of quantum physics from classical physics. The crucial ingredient of this formulation is Gozzi et al.'s supersymmetric path integral of classical mechanics. We quantize explicitly two simple classical systems: the planar mathematical pendulum and the Roessler dynamical system.
A survey of existing and proposed classical and quantum approaches to the photon mass
NASA Astrophysics Data System (ADS)
Spavieri, G.; Quintero, J.; Gillies, G. T.; Rodríguez, M.
2011-02-01
Over the past twenty years, there have been several careful experimental, observational and phenomenological investigations aimed at searching for and establishing ever tighter bounds on the possible mass of the photon. There are many fascinating and paradoxical physical implications that would arise from the presence of even a very small value for it, and thus such searches have always been well motivated in terms of the new physics that would result. We provide a brief overview of the theoretical background and classical motivations for this work and the early tests of the exactness of Coulomb's law that underlie it. We then go on to address the modern situation, in which quantum physics approaches come to attention. Among them we focus especially on the implications that the Aharonov-Bohm and Aharonov-Casher class of effects have on searches for a photon mass. These arise in several different ways and can lead to experiments that might involve the interaction of magnetic dipoles, electric dipoles, or charged particles with suitable potentials. Still other quantum-based approaches employ measurements of the g-factor of the electron. Plausible target sensitivities for limits on the photon mass as sought by the various quantum approaches are in the range of 10-53 to 10-54 g. Possible experimental arrangements for the associated experiments are discussed. We close with an assessment of the state of the art and a prognosis for future work.
NASA Astrophysics Data System (ADS)
Mokshin, A. V.
2015-04-01
The concept of time correlation functions is a very convenient theoretical tool in describing relaxation processes in multiparticle systems because, on one hand, correlation functions are directly related to experimentally measured quantities (for example, intensities in spectroscopic studies and kinetic coefficients via the Kubo-Green relation) and, on the other hand, the concept is also applicable beyond the equilibrium case. We show that the formalism of memory functions and the method of recurrence relations allow formulating a self-consistent approach for describing relaxation processes in classical multiparticle systems without needing a priori approximations of time correlation functions by model dependences and with the satisfaction of sum rules and other physical conditions guaranteed. We also demonstrate that the approach can be used to treat the simplest relaxation scenarios and to develop microscopic theories of transport phenomena in liquids, the propagation of density fluctuations in equilibrium simple liquids, and structure relaxation in supercooled liquids. This approach generalizes the mode-coupling approximation in the Götze-Leutheusser realization and the Yulmetyev-Shurygin correlation approximations.
Classical convergence versus Zipf rank approach: Evidence from China's local-level data
NASA Astrophysics Data System (ADS)
Tang, Pan; Zhang, Ying; Baaquie, Belal E.; Podobnik, Boris
2016-02-01
This paper applies Zipf rank approach to measure how long it will take for the individual economy to reach the final state of equilibrium by using local-level data of China's urban areas. The indicators, the gross domestic product (GDP) per capita and the market capitalization (MCAP) per capita of 150 major cities in China are used for analyzing their convergence. Besides, the power law relationship is examined for GDP and MCAP. Our findings show that, compared to the classical approaches: β-convergence and σ-convergence, the Zipf ranking predicts that, in approximately 16 years, all the major cities in China will reach comparable values of GDP per capita. However, the MCAP per capita tends to follow the periodic fluctuation of the economic cycle, while the mean-log derivation (MLD) confirms the results of our study. Moreover, GDP per capita and MCAP per capita follow a power law with an average value of α = 0.41 which is higher than α = 0.38 obtained based on a large number of countries around the world.
NASA Technical Reports Server (NTRS)
Tsue, Yasuhiko
1994-01-01
A general framework for time-dependent variational approach in terms of squeezed coherent states is constructed with the aim of describing quantal systems by means of classical mechanics including higher order quantal effects with the aid of canonicity conditions developed in the time-dependent Hartree-Fock theory. The Maslov phase occurring in a semi-classical quantization rule is investigated in this framework. In the limit of a semi-classical approximation in this approach, it is definitely shown that the Maslov phase has a geometric nature analogous to the Berry phase. It is also indicated that this squeezed coherent state approach is a possible way to go beyond the usual WKB approximation.
Pelzer, Kenley M.; Vázquez-Mayagoitia, Álvaro; Ratcliff, Laura E.; Tretiak, Sergei; Bair, Raymond A.; Gray, Stephen K.; Van Voorhis, Troy; Larsen, Ross E.; Darling, Seth B.
2017-01-01
Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. Here we propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower than most quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. In conclusion, much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Lastly, our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs.
Pelzer, Kenley M.; Vázquez-Mayagoitia, Álvaro; Ratcliff, Laura E.; ...
2017-01-11
Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. We propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower than mostmore » quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. Much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Lastly, our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs.« less
Pelzer, Kenley M.; Vázquez-Mayagoitia, Álvaro; Ratcliff, Laura E.; ...
2017-01-01
Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. Here we propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower thanmore » most quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. In conclusion, much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Lastly, our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs.« less
Schmiedt, Hanno; Schlemmer, Stephan; Yurchenko, Sergey N.; Yachmenev, Andrey
2017-01-01
We report a new semi-classical method to compute highly excited rotational energy levels of an asymmetric-top molecule. The method forgoes the idea of a full quantum mechanical treatment of the ro-vibrational motion of the molecule. Instead, it employs a semi-classical Green's function approach to describe the rotational motion, while retaining a quantum mechanical description of the vibrations. Similar approaches have existed for some time, but the method proposed here has two novel features. First, inspired by the path integral method, periodic orbits in the phase space and tunneling paths are naturally obtained by means of molecular symmetry analysis. Second, the rigorous variational method is employed for the first time to describe the molecular vibrations. In addition, we present a new robust approach to generating rotational energy surfaces for vibrationally excited states; this is done in a fully quantum-mechanical, variational manner. The semi-classical approach of the present work is applied to calculating the energies of very highly excited rotational states and it reduces dramatically the computing time as well as the storage and memory requirements when compared to the fullly quantum-mechanical variational approach. Test calculations for excited states of SO2 yield semi-classical energies in very good agreement with the available experimental data and the results of fully quantum-mechanical calculations. PMID:28000807
Schmiedt, Hanno; Schlemmer, Stephan; Yurchenko, Sergey N; Yachmenev, Andrey; Jensen, Per
2017-01-18
We report a new semi-classical method to compute highly excited rotational energy levels of an asymmetric-top molecule. The method forgoes the idea of a full quantum mechanical treatment of the ro-vibrational motion of the molecule. Instead, it employs a semi-classical Green's function approach to describe the rotational motion, while retaining a quantum mechanical description of the vibrations. Similar approaches have existed for some time, but the method proposed here has two novel features. First, inspired by the path integral method, periodic orbits in the phase space and tunneling paths are naturally obtained by means of molecular symmetry analysis. Second, the rigorous variational method is employed for the first time to describe the molecular vibrations. In addition, we present a new robust approach to generating rotational energy surfaces for vibrationally excited states; this is done in a fully quantum-mechanical, variational manner. The semi-classical approach of the present work is applied to calculating the energies of very highly excited rotational states and it reduces dramatically the computing time as well as the storage and memory requirements when compared to the fullly quantum-mechanical variational approach. Test calculations for excited states of SO2 yield semi-classical energies in very good agreement with the available experimental data and the results of fully quantum-mechanical calculations.
Capacity limitations of a classic M-power measure: a modified dual-task approach.
Foley, E J; Berch, D B
1997-08-01
A modified dual-task approach was employed with 7- to 9-year-olds in an effort to determine whether one of the classic M-power measures, the digit placement task, is indeed capacity-limited. To this end, a computerized version of a three-item digit placement task was administered in addition to three other computerized tasks: a four-item digit placement task, simple reaction time (RT) to a tone presented alone, and reaction time to a tone occurring during the performance of another three-item digit placement task. Careful examination of the data revealed that several critical assumptions concerning the use of the dual-task procedure were successfully met. This permitted a test of the extent to which dual-task RTs were predictive of accuracy in the harder, four-item digit placement task. Not only was this relationship significant, but after partialling out other possible sources of variance, a significant correlation remained, indicating that the digit placement task is indeed capacity-limited.
2017-01-01
This paper provides evidence on the usefulness of very high spatial resolution (VHR) imagery in gathering socioeconomic information in urban settlements. We use land cover, spectral, structure and texture features extracted from a Google Earth image of Liverpool (UK) to evaluate their potential to predict Living Environment Deprivation at a small statistical area level. We also contribute to the methodological literature on the estimation of socioeconomic indices with remote-sensing data by introducing elements from modern machine learning. In addition to classical approaches such as Ordinary Least Squares (OLS) regression and a spatial lag model, we explore the potential of the Gradient Boost Regressor and Random Forests to improve predictive performance and accuracy. In addition to novel predicting methods, we also introduce tools for model interpretation and evaluation such as feature importance and partial dependence plots, or cross-validation. Our results show that Random Forest proved to be the best model with an R2 of around 0.54, followed by Gradient Boost Regressor with 0.5. Both the spatial lag model and the OLS fall behind with significantly lower performances of 0.43 and 0.3, respectively. PMID:28464010
Arribas-Bel, Daniel; Patino, Jorge E; Duque, Juan C
2017-01-01
This paper provides evidence on the usefulness of very high spatial resolution (VHR) imagery in gathering socioeconomic information in urban settlements. We use land cover, spectral, structure and texture features extracted from a Google Earth image of Liverpool (UK) to evaluate their potential to predict Living Environment Deprivation at a small statistical area level. We also contribute to the methodological literature on the estimation of socioeconomic indices with remote-sensing data by introducing elements from modern machine learning. In addition to classical approaches such as Ordinary Least Squares (OLS) regression and a spatial lag model, we explore the potential of the Gradient Boost Regressor and Random Forests to improve predictive performance and accuracy. In addition to novel predicting methods, we also introduce tools for model interpretation and evaluation such as feature importance and partial dependence plots, or cross-validation. Our results show that Random Forest proved to be the best model with an R2 of around 0.54, followed by Gradient Boost Regressor with 0.5. Both the spatial lag model and the OLS fall behind with significantly lower performances of 0.43 and 0.3, respectively.
General Approach to Quantum Channel Impossibility by Local Operations and Classical Communication.
Cohen, Scott M
2017-01-13
We describe a general approach to proving the impossibility of implementing a quantum channel by local operations and classical communication (LOCC), even with an infinite number of rounds, and find that this can often be demonstrated by solving a set of linear equations. The method also allows one to design a LOCC protocol to implement the channel whenever such a protocol exists in any finite number of rounds. Perhaps surprisingly, the computational expense for analyzing LOCC channels is not much greater than that for LOCC measurements. We apply the method to several examples, two of which provide numerical evidence that the set of quantum channels that are not LOCC is not closed and that there exist channels that can be implemented by LOCC either in one round or in three rounds that are on the boundary of the set of all LOCC channels. Although every LOCC protocol must implement a separable quantum channel, it is a very difficult task to determine whether or not a given channel is separable. Fortunately, prior knowledge that the channel is separable is not required for application of our method.
General Approach to Quantum Channel Impossibility by Local Operations and Classical Communication
NASA Astrophysics Data System (ADS)
Cohen, Scott M.
2017-01-01
We describe a general approach to proving the impossibility of implementing a quantum channel by local operations and classical communication (LOCC), even with an infinite number of rounds, and find that this can often be demonstrated by solving a set of linear equations. The method also allows one to design a LOCC protocol to implement the channel whenever such a protocol exists in any finite number of rounds. Perhaps surprisingly, the computational expense for analyzing LOCC channels is not much greater than that for LOCC measurements. We apply the method to several examples, two of which provide numerical evidence that the set of quantum channels that are not LOCC is not closed and that there exist channels that can be implemented by LOCC either in one round or in three rounds that are on the boundary of the set of all LOCC channels. Although every LOCC protocol must implement a separable quantum channel, it is a very difficult task to determine whether or not a given channel is separable. Fortunately, prior knowledge that the channel is separable is not required for application of our method.
Stott, Clifford; Drury, John
2016-04-01
This article explores the origins and ideology of classical crowd psychology, a body of theory reflected in contemporary popularised understandings such as of the 2011 English 'riots'. This article argues that during the nineteenth century, the crowd came to symbolise a fear of 'mass society' and that 'classical' crowd psychology was a product of these fears. Classical crowd psychology pathologised, reified and decontextualised the crowd, offering the ruling elites a perceived opportunity to control it. We contend that classical theory misrepresents crowd psychology and survives in contemporary understanding because it is ideological. We conclude by discussing how classical theory has been supplanted in academic contexts by an identity-based crowd psychology that restores the meaning to crowd action, replaces it in its social context and in so doing transforms theoretical understanding of 'riots' and the nature of the self. © The Author(s) 2016.
ERIC Educational Resources Information Center
Wilson, Mark; Allen, Diane D.; Li, Jun Corser
2006-01-01
This paper compares the approach and resultant outcomes of item response models (IRMs) and classical test theory (CTT). First, it reviews basic ideas of CTT, and compares them to the ideas about using IRMs introduced in an earlier paper. It then applies a comparison scheme based on the AERA/APA/NCME "Standards for Educational and…
ERIC Educational Resources Information Center
García, Nuria Alonso; Caplan, Alison
2014-01-01
While there are a number of important critical pedagogies being proposed in the field of foreign language study, more attention should be given to providing concrete examples of how to apply these ideas in the classroom. This article offers a new approach to the textual analysis of literary classics through the keyword-based methodology originally…
ERIC Educational Resources Information Center
García, Nuria Alonso; Caplan, Alison
2014-01-01
While there are a number of important critical pedagogies being proposed in the field of foreign language study, more attention should be given to providing concrete examples of how to apply these ideas in the classroom. This article offers a new approach to the textual analysis of literary classics through the keyword-based methodology originally…
ERIC Educational Resources Information Center
Wilson, Mark; Allen, Diane D.; Li, Jun Corser
2006-01-01
This paper compares the approach and resultant outcomes of item response models (IRMs) and classical test theory (CTT). First, it reviews basic ideas of CTT, and compares them to the ideas about using IRMs introduced in an earlier paper. It then applies a comparison scheme based on the AERA/APA/NCME "Standards for Educational and…
NASA Astrophysics Data System (ADS)
Schmiedt, Hanno; Schlemmer, Stephan; Yurchenko, Sergei N.; Yachmenev, Andrey; Jensen, Per
2017-06-01
We report a new semi-classical method to compute highly excited rotational energy levels of an asymmetric-top molecule. The method forgoes the idea of a full quantum mechanical treatment of the ro-vibrational motion of the molecule. Instead, it employs a semi-classical Green's function approach to describe the rotational motion, while retaining a quantum mechanical description of the vibrations. Similar approaches have existed for some time, but the method proposed here has two novel features. First, inspired by the path integral method, periodic orbits in the phase space and tunneling paths are naturally obtained by means of molecular symmetry analysis. Second, the rigorous variational method is employed for the first time to describe the molecular vibrations. In addition, we present a new robust approach to generating rotational energy surfaces for vibrationally excited states; this is done in a fully quantum-mechanical, variational manner. The semi-classical approach of the present work is applied to calculating the energies of very highly excited rotational states and it reduces dramatically the computing time as well as the storage and memory requirements when compared to the fully quantum-mechanical variational approach. Test calculations for excited states of SO_2 yield semi-classical energies in very good agreement with the available experimental data and the results of fully quantum-mechanical calculations. We hope to be able to present at the meeting also semi-classical calculations of transition intensities. See also the open-access paper Phys. Chem. Chem. Phys. 19, 1847-1856 (2017). DOI: 10.1039/C6CP05589C
Dynamically consistent method for mixed quantum-classical simulations: A semiclassical approach.
Antipov, Sergey V; Ye, Ziyu; Ananth, Nandini
2015-05-14
We introduce a new semiclassical (SC) framework, the Mixed Quantum-Classical Initial Value Representation (MQC-IVR), that can be tuned to reproduce existing quantum-limit and classical-limit SC approximations to quantum real-time correlation functions. Applying a modified Filinov transformation to a quantum-limit SC formulation leads to the association of a Filinov parameter with each degree of freedom in the system; varying this parameter from zero to infinity controls the extent of quantization of the corresponding mode. The resulting MQC-IVR expression provides a consistent dynamic framework for mixed quantum-classical simulations and we demonstrate its numerical accuracy in the calculation of real-time correlation functions for a model 1D system and a model 2D system over the full range of quantum- to classical-limit behaviors.
Dynamically consistent method for mixed quantum-classical simulations: A semiclassical approach
Antipov, Sergey V.; Ye, Ziyu; Ananth, Nandini
2015-05-14
We introduce a new semiclassical (SC) framework, the Mixed Quantum-Classical Initial Value Representation (MQC-IVR), that can be tuned to reproduce existing quantum-limit and classical-limit SC approximations to quantum real-time correlation functions. Applying a modified Filinov transformation to a quantum-limit SC formulation leads to the association of a Filinov parameter with each degree of freedom in the system; varying this parameter from zero to infinity controls the extent of quantization of the corresponding mode. The resulting MQC-IVR expression provides a consistent dynamic framework for mixed quantum-classical simulations and we demonstrate its numerical accuracy in the calculation of real-time correlation functions for a model 1D system and a model 2D system over the full range of quantum- to classical-limit behaviors.
Teaching Statistics Using Classic Psychology Research: An Activities-Based Approach
ERIC Educational Resources Information Center
Holmes, Karen Y.; Dodd, Brett A.
2012-01-01
In this article, we discuss a collection of active learning activities derived from classic psychology studies that illustrate the appropriate use of descriptive and inferential statistics. (Contains 2 tables.)
Teaching Statistics Using Classic Psychology Research: An Activities-Based Approach
ERIC Educational Resources Information Center
Holmes, Karen Y.; Dodd, Brett A.
2012-01-01
In this article, we discuss a collection of active learning activities derived from classic psychology studies that illustrate the appropriate use of descriptive and inferential statistics. (Contains 2 tables.)
Classical Novae Blow Smoke Rings: A DIRTY Approach to Modeling Dust Formation
NASA Astrophysics Data System (ADS)
Bornak, Jillian; Harrison, T. E.; Gordon, K. D.
2012-01-01
Classical novae (CNe) are convenient objects for studying dust formation. While they are not the dust-producing workhorses that AGB stars are, CNe provide a way to study a single epoch of dust formation. Estimates of dust masses in some novae have implied a large portion (if not all!) of the gas is turned into dust, which is not physical. We propose for these objects the problem lies in estimating the dust mass. We present a new approach using the dust radiative transfer code DIRTY. We chose this code for its ability to model various geometries and for including the effects of scattered light and transient heating of small grains. We have an extensive and unpublished time series of OIR photometry with select nights of spectroscopy for the dusty nova V868 Cen (Nova Cen 91). Our work is innovative for simultaneously modeling the optical (central engine) emission and the IR (dust shell) emission, whereas previous studies have only modeled the IR emission, allowing us to account for ``contamination" of short-wavelength IR by scattered optical light. Our initial models used the simplest geometry, a spherical shell either homogeneous or ``clumpy". While the spherical shell model could fit individual nights, it could not match the temporal evolution of the nova. Multiple studies of gas emission line profiles indicate that CNe ejecta shells have an ellipsoidal geometry with equatorial, tropical, and polar overdensities. We find that a torus model is a better fit for single nights of data as well as matching the temporal evolution of the nova. We present our results showing the formation, growth, and destruction of dust grains. We show importance of geometry on dust mass estimates and take the first steps to determine the physical location of dust formation in CNe.
Extended hydrodynamic approach to quantum-classical nonequilibrium evolution. I. Theory.
Bousquet, David; Hughes, Keith H; Micha, David A; Burghardt, Irene
2011-02-14
A mixed quantum-classical formulation is developed for a quantum subsystem in strong interaction with an N-particle environment, to be treated as classical in the framework of a hydrodynamic representation. Starting from the quantum Liouville equation for the N-particle distribution and the corresponding reduced single-particle distribution, exact quantum hydrodynamic equations are obtained for the momentum moments of the single-particle distribution coupled to a discretized quantum subsystem. The quantum-classical limit is subsequently taken and the resulting hierarchy of equations is further approximated by various closure schemes. These include, in particular, (i) a Grad-Hermite-type closure, (ii) a Gaussian closure at the level of a quantum-classical local Maxwellian distribution, and (iii) a dynamical density functional theory approximation by which the hydrodynamic pressure term is replaced by a free energy functional derivative. The latter limit yields a mixed quantum-classical formulation which has previously been introduced by I. Burghardt and B. Bagchi, Chem. Phys. 134, 343 (2006).
A unified approach to quantum and classical TTW systems based on factorizations
Celeghini, E.; Kuru, Ş.; Negro, J.; Olmo, M.A. del
2013-05-15
A unifying method based on factorization properties is introduced for finding symmetries of quantum and classical superintegrable systems using the example of the Tremblay–Turbiner–Winternitz (TTW) model. It is shown that the symmetries of the quantum system can be implemented in a natural way to its classical version. Besides, by this procedure we get also other type of constants of motion depending explicitly on time that allow to find directly the motion of the system whose corresponding trajectories coincide with those obtained previously by using its symmetries. -- Highlights: ► A unified method is given to find symmetries of classical and quantum systems. ► Ladder–shift operators and functions have analog expressions and relations. ► This method is applied to the TTW system to obtain its symmetries. ► For the classical cases a set of time dependent constants of motion are obtained. ► They allow us to find directly the motion and trajectories.
The Bread and Butter of Classical Organizational Approaches: The Time-and-Motion Study
ERIC Educational Resources Information Center
Peterson, Dan W.
2007-01-01
The thought of learning about the principles of classical management and the machine metaphor of organizing can get many organizational communication students yawning just by seeing the subject in a syllabus. Abundant movie and television examples associated with the machine-like nature of workplace productivity are often used to demonstrate…
Petrov, S.V.; Katsov, K.M.
1995-05-01
A method for constructing the effective rotational Hamiltonian for an isolated vibrational state directly from the classical vibrational-rotational Hamiltonian function, without invoking the experimental data on rotational spectra, is suggested. Test calculations are carried out for diatomic molecules. The relative accuracy of the rotational-level calculations is on the order of 10{sup -5}. 17 refs., 2 tabs.
The Bread and Butter of Classical Organizational Approaches: The Time-and-Motion Study
ERIC Educational Resources Information Center
Peterson, Dan W.
2007-01-01
The thought of learning about the principles of classical management and the machine metaphor of organizing can get many organizational communication students yawning just by seeing the subject in a syllabus. Abundant movie and television examples associated with the machine-like nature of workplace productivity are often used to demonstrate…
Applying molecular-based approaches to classical biological control of weeds
USDA-ARS?s Scientific Manuscript database
Modern advances in molecular techniques are only recently being incorporated into programs for the classical biological control of weeds. Molecular analyses are able to elucidate information about target weeds that is critical to improving control success, such as taxonomic clarification, evidence o...
Quantum-classical correspondences for atomic operators: a positive P representation approach
NASA Astrophysics Data System (ADS)
You, L.; Cooper, J.; Zoller, P.
1995-10-01
We demonstrate the successful simulation of classical stochastic differential equations obtained from the positive P phase-space technique for two-level atoms pumped by a near-resonant laser. Numerical results for both the resonance fluorescence spectrum and the absorption spectrum are compared with the exact results. Copyright (c) 1995 Optical Society of America
John Stirling and the Classical Approach to Style in 18th Century England.
ERIC Educational Resources Information Center
Moran, Michael G.
Most 18th-century rhetoricians viewed style as the expression of a writer's individual character and thought, placing little emphasis on the lists of figures common in many 17th-century rhetorics. John Stirling and others, however, continued the 17th-century tradition that reduced rhetoric largely to style and emphasized classical figures of…
Increasing incidence of thyroid cancer in Great Britain, 1976-2005: age-period-cohort analysis.
McNally, Richard J Q; Blakey, Karen; James, Peter W; Gomez Pozo, Basilio; Basta, Nermine O; Hale, Juliet
2012-08-01
Increases in the incidence of thyroid cancer have been previously reported. The purpose of the present study was to examine temporal trends in the incidence of primary thyroid cancer diagnosed in 0-49 year olds in parts of Great Britain during 1976-2005. Data on 4,337 cases of thyroid cancer were obtained from regional cancer registries. Age-standardized incidence rates (ASRs) were calculated. Negative binomial regression was used to examine effects of age, sex, drift (linear trend), non-linear period and non-linear cohort. The best fitting negative binomial regression model included age (P < 0.001), sex (P < 0.001) and drift (P < 0.001). Non-linear period (P = 0.648) and non-linear cohort (P = 0.788) were not statistically significant. For males aged 0-14, the ASR increased from 0.2 per million persons per year in 1976-1986 to 0.6 in 1997-2005. For males aged 15-29 and 30-49 the ASRs increased from 1.9 to 3.3 and from 7.4 to 12.7, respectively. For females aged 0-14, the corresponding ASR increased from 0.3 to 0.5. For females aged 15-29 and 30-49 the ASRs increased from 6.9 to 12.4 and from 21.2 to 42.3, respectively. For all age groups, there has been a linear increase in incidence of thyroid cancer, which has led to a doubling of the number of cases diagnosed over a twenty year span. The reasons for this increase are not well understood, but it is consistent with findings from other countries.
Age-period-cohort analysis of suicide mortality rates in Spain, 1959-1991.
Granizo, J J; Guallar, E; Rodríguez-Artalejo, F
1996-08-01
Although there is evidence that suicide rates may be increasing in Spain, formal epidemiological studies have been limited to specific cities or counties. The objective of this study was to investigate nationwide trends in suicide mortality from 1959 to 1991 in Spain, with emphasis on age, period, and cohort effects. Age- and sex-specific suicide mortality rates from 1959 until 1991 were obtained from official vital statistics tables from the Instituto Nacional de Estadística, the official registry of vital statistics in Spain. Poisson regression and graphical methods were used to model and estimate age, period and cohort effects. Suicide mortality rates increased with age, with a proportional increment for each decade of life of 45% (95% confidence interval: 45-46%). In both males and females, age-adjusted suicide mortality rates decreased from 1959 until the late 1970s and early 1980s. In 1982, trends started to increase, returning to the levels of 1959 in less than 6 years. Cohort effects were small for cohorts born prior to 1940. For cohorts born after 1950, suicide rates increased markedly. The increase in suicide mortality in younger cohorts and the high rates of suicide in the elderly demand further investigation to establish causal mechanisms and preventive strategies.
An empirical analysis of US and Japanese health insurance using age-period-cohort decomposition.
Fukuda, Kosei
2007-05-01
Aggregate data on household health insurance expenditure in the US and Japan that are classified by period and age are decomposed into age, period, and cohort effects by using the Bayesian cohort models. These models are developed to overcome the identification problem involved in cohort analysis. Despite the differences between the health insurance systems of the two countries, three interesting empirical findings are obtained. First, in both the countries, the age effects are the most influential, and the cohort effects have negligible influence. The latter provides a striking policy implication since the generational imbalance in social security expenditures is widely recognized in developed countries. Second, in both the countries, the period effects show a roughly upward trend. Finally, the age effects exhibit a roughly upward movement for all age groups in the US; however, in Japan, these effects show a downward movement for the 55-59 age group due to the changes in the health insurance system on retirement. Copyright (c) 2006 John Wiley & Sons, Ltd.
Understanding trends in Australian alcohol consumption-an age-period-cohort model.
Livingston, Michael; Raninen, Jonas; Slade, Tim; Swift, Wendy; Lloyd, Belinda; Dietze, Paul
2016-09-01
To decompose Australian trends in alcohol consumption into their age, period (survey year) and cohort (birth year/generation) components. In particular, we aimed to test whether recent declines in overall consumption have been influenced by reductions in drinking among recently born cohorts. Seven cross-sectional waves of the Australian National Drug Strategy Household Survey (1995-2013). Age, period and cohort effects were estimated using a linear and logistic cross-classified random-effects models (CCREMs). Australia A total of 124 440 Australians (69 193 females and 55 257 males), aged 14-79 years. Whether or not respondents consumed alcohol in the 12 months prior to the survey and, for those who did, the estimated volume of pure alcohol consumed, derived using standard quantity-frequency survey questions. Controlling for age and period effects, there was significant variation in drinking participation and drinking volume by birth cohort. In particular, male cohorts born between the 1965 and 1974 and female cohorts born between 1955 and 1974 reported higher rates of drinking participation (P < 0.05), while the most recent cohorts (born in the 1990s) had lower rates of participation (P < 0.01). Among drinkers, the most recently born cohort also had sharply lower average consumption volumes than older cohorts for both men and women (P < 0.01). Recent birth cohorts (born between 1995 and 1999) in Australia report significantly lower rates of both drinking participation and drinking volume than previous cohorts, controlling for their age distribution and overall changes in population drinking. These findings suggest that the recent decline in alcohol consumption in Australia has been driven by declines in drinking among these recently born cohorts. These trends are consistent with international shifts in youth drinking. © 2016 Society for the Study of Addiction.
Breast cancer mortality in Mexico: an age-period-cohort analysis.
Franco-Marina, Francisco; Lazcano-Ponce, Eduardo; López-Carrillo, Lizbeth
2009-01-01
To assess the age, period and cohort effects on breast cancer (BC) mortality in Mexico. Age, period and cohort curvature trends for BC mortality were estimated through the Poisson Regression model proposed by Holford. Nationally, BC death rates have leveled off since 1995 in most age groups. BC mortality trends are mainly determined by birth cohort and age effects in Mexico. Women born between 1940 and 1955 show the highest rate of increase in BC mortality. Women born afterwards still show an increasing trend but at a much lower rate. Mammography and adjuvant therapy have had a limited impact on mortality. Potential reasons for observed patterns are discussed. An increase in BC mortality in Mexico is expected in the following decades. Mammography screening programs and timely access to effective treatment should be a national priority to reverse the expected increasing BC mortality trend.
Materialism across the life span: An age-period-cohort analysis.
Jaspers, Esther D T; Pieters, Rik G M
2016-09-01
This research examined the development of materialism across the life span. Two initial studies revealed that (a) lay beliefs were that materialism declines with age and (b) previous research findings also implied a modest, negative relationship between age and materialism. Yet, previous research has considered age only as a linear control variable, thereby precluding the possibility of more intricate relationships between age and materialism. Moreover, prior studies have relied on cross-sectional data and thus confound age and cohort effects. To improve on this, the main study used longitudinal data from 8 waves spanning 9 years of over 4,200 individuals (16 to 90 years) to examine age effects on materialism while controlling for cohort and period effects. Using a multivariate multilevel latent growth model, it found that materialism followed a curvilinear trajectory across the life span, with the lowest levels at middle age and higher levels before and after that. Thus, in contrast to lay beliefs, materialism increased in older age. Moreover, age effects on materialism differed markedly between 3 core themes of materialism: acquisition centrality, possession-defined success, and acquisition as the pursuit of happiness. In particular, acquisition centrality and possession-defined success were higher at younger and older age. Independent of these age effects, older birth cohorts were oriented more toward possession-defined success, whereas younger birth cohorts were oriented more toward acquisition centrality. The economic downturn since 2008 led to a decrease in acquisition as the pursuit of happiness and in desires for personal growth, but to an increase in desires for achievement. (PsycINFO Database Record
NASA Astrophysics Data System (ADS)
McMillan, Ryan J.; Stella, Lorenzo; Grüning, Myrta
2016-09-01
We introduce a hybrid method for dielectric-metal composites that describes the dynamics of the metallic system classically while retaining a quantum description of the dielectric. The time-dependent dipole moment of the classical system is mimicked by the introduction of projected equations of motion (PEOM), and the coupling between the two systems is achieved through an effective dipole-dipole interaction. To benchmark this method, we model a test system (semiconducting quantum dot-metal nanoparticle hybrid). We begin by examining the energy absorption rate, showing agreement between the PEOM method and the analytical rotating wave approximation (RWA) solution. We then investigate population inversion and show that the PEOM method provides an accurate model for the interaction under ultrashort pulse excitation where the traditional RWA breaks down.
Semi-classical approach to compute RABBITT traces in multi-dimensional complex field distributions.
Lucchini, M; Ludwig, A; Kasmi, L; Gallmann, L; Keller, U
2015-04-06
We present a semi-classical model to calculate RABBITT (Reconstruction of Attosecond Beating By Interference of Two-photon Transitions) traces in the presence of a reference infrared field with a complex two-dimensional (2D) spatial distribution. The evolution of the electron spectra as a function of the pump-probe delay is evaluated starting from the solution of the classical equation of motion and incorporating the quantum phase acquired by the electron during the interaction with the infrared field. The total response to an attosecond pulse train is then evaluated by a coherent sum of the contributions generated by each individual attosecond pulse in the train. The flexibility of this model makes it possible to calculate spectrograms from non-trivial 2D field distributions. After confirming the validity of the model in a simple 1D case, we extend the discussion to describe the probe-induced phase in photo-emission experiments on an ideal metallic surface.
A Plasma Proteomic Approach in Rett Syndrome: Classical versus Preserved Speech Variant
Cortelazzo, Alessio; Guerranti, Roberto; De Felice, Claudio; Leoncini, Silvia; Landi, Claudia; Montomoli, Barbara; Sticozzi, Claudia; Ciccoli, Lucia; Hayek, Joussef
2013-01-01
Rett syndrome (RTT) is a progressive neurodevelopmental disorder mainly caused by mutations in the gene encoding the methyl-CpG-binding protein 2 (MeCP2). Although over 200 mutations types have been identified so far, nine of which the most frequent ones. A wide phenotypical heterogeneity is a well-known feature of the disease, with different clinical presentations, including the classical form and the preserved speech variant (PSV). Aim of the study was to unveil possible relationships between plasma proteome and phenotypic expression in two cases of familial RTT represented by two pairs of sisters, harbor the same MECP2 gene mutation while being dramatically discrepant in phenotype, that is, classical RTT versus PSV. Plasma proteome was analysed by 2-DE/MALDI-TOF MS. A significant overexpression of six proteins in the classical sisters was detected as compared to the PSV siblings. A total of five out of six (i.e., 83.3%) of the overexpressed proteins were well-known acute phase response (APR) proteins, including alpha-1-microglobulin, haptoglobin, fibrinogen beta chain, alpha-1-antitrypsin, and complement C3. Therefore, the examined RTT siblings pairs proved to be an important benchmark model to test the molecular basis of phenotypical expression variability and to identify potential therapeutic targets of the disease. PMID:24453418
A plasma proteomic approach in Rett syndrome: classical versus preserved speech variant.
Cortelazzo, Alessio; Guerranti, Roberto; De Felice, Claudio; Signorini, Cinzia; Leoncini, Silvia; Pecorelli, Alessandra; Landi, Claudia; Bini, Luca; Montomoli, Barbara; Sticozzi, Claudia; Ciccoli, Lucia; Valacchi, Giuseppe; Hayek, Joussef
2013-01-01
Rett syndrome (RTT) is a progressive neurodevelopmental disorder mainly caused by mutations in the gene encoding the methyl-CpG-binding protein 2 (MeCP2). Although over 200 mutations types have been identified so far, nine of which the most frequent ones. A wide phenotypical heterogeneity is a well-known feature of the disease, with different clinical presentations, including the classical form and the preserved speech variant (PSV). Aim of the study was to unveil possible relationships between plasma proteome and phenotypic expression in two cases of familial RTT represented by two pairs of sisters, harbor the same MECP2 gene mutation while being dramatically discrepant in phenotype, that is, classical RTT versus PSV. Plasma proteome was analysed by 2-DE/MALDI-TOF MS. A significant overexpression of six proteins in the classical sisters was detected as compared to the PSV siblings. A total of five out of six (i.e., 83.3%) of the overexpressed proteins were well-known acute phase response (APR) proteins, including alpha-1-microglobulin, haptoglobin, fibrinogen beta chain, alpha-1-antitrypsin, and complement C3. Therefore, the examined RTT siblings pairs proved to be an important benchmark model to test the molecular basis of phenotypical expression variability and to identify potential therapeutic targets of the disease.
Herbers, Claudia R; Johnston, Karen; van der Vegt, Nico F A
2011-06-14
We present an automated and efficient method to develop force fields for molecule-surface interactions. A genetic algorithm (GA) is used to parameterise a classical force field so that the classical adsorption energy landscape of a molecule on a surface matches the corresponding landscape from density functional theory (DFT) calculations. The procedure performs a sophisticated search in the parameter phase space and converges very quickly. The method is capable of fitting a significant number of structures and corresponding adsorption energies. Water on a ZnO(0001) surface was chosen as a benchmark system but the method is implemented in a flexible way and can be applied to any system of interest. In the present case, pairwise Lennard Jones (LJ) and Coulomb potentials are used to describe the molecule-surface interactions. In the course of the fitting procedure, the LJ parameters are refined in order to reproduce the adsorption energy landscape. The classical model is capable of describing a wide range of energies, which is essential for a realistic description of a fluid-solid interface.
Shakib, Farnaz A; Hanna, Gabriel
2014-07-28
The nonadiabatic dynamics of model proton-coupled electron transfer (PCET) reactions is investigated for the first time using a surface-hopping algorithm based on the solution of the mixed quantum-classical Liouville equation (QCLE). This method provides a rigorous treatment of quantum coherence/decoherence effects in the dynamics of mixed quantum-classical systems, which is lacking in the molecular dynamics with quantum transitions surface-hopping approach commonly used for simulating PCET reactions. Within this approach, the protonic and electronic coordinates are treated quantum mechanically and the solvent coordinate evolves classically on both single adiabatic surfaces and on coherently coupled pairs of adiabatic surfaces. Both concerted and sequential PCET reactions are studied in detail under various subsystem-bath coupling conditions and insights into the dynamical principles underlying PCET reactions are gained. Notably, an examination of the trajectories reveals that the system spends the majority of its time on the average of two coherently coupled adiabatic surfaces, during which a phase enters into the calculation of an observable. In general, the results of this paper demonstrate the applicability of QCLE-based surface-hopping dynamics to the study of PCET and emphasize the importance of mean surface evolution and decoherence effects in the calculation of PCET rate constants.
Shakib, Farnaz A.; Hanna, Gabriel
2014-07-28
The nonadiabatic dynamics of model proton-coupled electron transfer (PCET) reactions is investigated for the first time using a surface-hopping algorithm based on the solution of the mixed quantum-classical Liouville equation (QCLE). This method provides a rigorous treatment of quantum coherence/decoherence effects in the dynamics of mixed quantum-classical systems, which is lacking in the molecular dynamics with quantum transitions surface-hopping approach commonly used for simulating PCET reactions. Within this approach, the protonic and electronic coordinates are treated quantum mechanically and the solvent coordinate evolves classically on both single adiabatic surfaces and on coherently coupled pairs of adiabatic surfaces. Both concerted and sequential PCET reactions are studied in detail under various subsystem-bath coupling conditions and insights into the dynamical principles underlying PCET reactions are gained. Notably, an examination of the trajectories reveals that the system spends the majority of its time on the average of two coherently coupled adiabatic surfaces, during which a phase enters into the calculation of an observable. In general, the results of this paper demonstrate the applicability of QCLE-based surface-hopping dynamics to the study of PCET and emphasize the importance of mean surface evolution and decoherence effects in the calculation of PCET rate constants.
Classical and numerical approaches to determining V-section band clamp axial stiffness
NASA Astrophysics Data System (ADS)
Barrans, Simon M.; Khodabakhshi, Goodarz; Muller, Matthias
2014-12-01
V-band clamp joints are used in a wide range of applications to connect circular flanges, for ducts, pipes and the turbocharger housing. Previous studies and research on V-bands are either purely empirical or analytical with limited applicability on the variety of V-band design and working conditions. In this paper models of the V-band are developed based on the classical theory of solid mechanics and the finite element method to study the behaviour of theV-bands under axial loading conditions. The good agreement between results from the developed FEA and the classical model support the suitability of the latter to modelV-band joints with diameters greater than 110mm under axial loading. The results from both models suggest that the axial stiffness for thisV-band cross section reaches a peak value for V-bands with radius of approximately 150 mmacross a wide range of coefficients of friction. Also, it is shown that the coefficient of friction and the wedge angle have a significant effect on the axial stiffness of V-bands.
A Stochastic Foundation of the Approach to Equilibrium of Classical and Quantum Gases
NASA Astrophysics Data System (ADS)
Costantini, D.; Garibaldi, U.
The Ehrenfest urn model is one of the most instructive models in the whole of Physics. It was thought to give a qualitative account for notions like reversibility, periodicity and tendency to equilibrium. The model, often referred to as the Ehrenfest dog-flea model, is mentioned in almost every textbook of probability, stochastic processes and statistical physics. Ehrenfest's model must not be limited to classical particles, but it can be extended to quantum particles. We make this extention in a purely probabilistic way. We do not refer to notions like (in)distinguishability that, in our opinion, have an epistemological and physical status far from clear. For all types of particles, we deduce the equilibrium probabilities in a purely probabilistic way. To accomplish our goal, we start by considering a set of probability conditions. On this basis, we deduce the formulae of creation and destruction probabilities for classical particles, bosons and fermions. These enable the deduction of the transition probabilities we are interested in. Via the master equation, these transition probabilities enable us to derive the equilibrium distributions.
NASA Astrophysics Data System (ADS)
Castellanos, L.; Calás, H.; Ramos, A.
2010-01-01
In this paper, an approach for simplifying the experimental arrangement, needed to generate limited diffracting waves through annular ultrasonic arrays, is analyzed in terms mainly of the subsequent acoustic field. The main idea is to approximate the theoretical X-wave electrical excitations to rectangular driving signals in each array annulus, by means of the L2 curve criterion. The differences between theoretical X-wave signals and these approximate signals, related to real excitation effects, were minimized by using the transition times and amplitudes of the rectangular signals as fitting parameters. Acoustic field simulations, based on the impulse response technique, are applied for evaluating the agreement degree between both emitted ultrasonic fields, whit the calculated classical X wave and with the new approximation method proposed here for low-cost limited-diffraction wave generation. In addition, source vibration and ultrasonic field simulated signals were compared with those of the classic x wave under an exact driving, with the purpose of validating the method. The good agreement between the two vibration signals and resulting field distributions, obtained from the classical X wave excitations and those provided by the drastic simplification presented here, can be justified by the filtering effects induced by the transducer elements bands in frequency domain. These results suggest the possibility of achieving limited diffraction waves with relatively simple driving waveforms, which can be implemented with a moderate cost in analogical electronics.
Sequencing approach to analyze the role of quasispecies for classical swine fever.
Töpfer, Armin; Höper, Dirk; Blome, Sandra; Beer, Martin; Beerenwinkel, Niko; Ruggli, Nicolas; Leifer, Immanuel
2013-03-30
Classical swine fever virus (CSFV) is a positive-sense RNA virus with a high degree of genetic variability among isolates. High diversity is also found in virulence, with strains covering the complete spectrum from avirulent to highly virulent. The underlying genetic determinants are far from being understood. Since RNA polymerases of RNA viruses lack any proof-reading activity, different genome variations called haplotypes, occur during replication. A set of haplotypes is referred to as a viral quasispecies. Genetic variability can be a fitness advantage through facilitating of a more effective escape from the host immune response. In order to investigate the correlation of quasispecies composition and virulence in vivo, we analyzed next-generation sequencing data of CSFV isolates of varying virulence. Viral samples from pigs infected with the highly virulent isolates "Koslov" and "Brescia" showed higher quasispecies diversity and more nucleotide variability, compared to samples of pigs infected with low and moderately virulent isolates.
Doomsdays in a modified theory of gravity: A classical and a quantum approach
NASA Astrophysics Data System (ADS)
Albarran, Imanol; Bouhmadi-López, Mariam; Chen, Che-Yu; Chen, Pisin
2017-09-01
By far cosmology is one of the most exciting subject to study, even more so with the current bulk of observations we have at hand. These observations might indicate different kinds of doomsdays, if dark energy follows certain patterns. Two of these doomsdays are the Little Rip (LR) and Little Sibling of the Big Rip (LSBR). In this work, aside from proving the unavoidability of the LR and LSBR in the Eddington-inspired-Born-Infeld (EiBI) scenario, we carry out a quantum analysis of the EiBI theory with a matter field, which, from a classical point of view would inevitably lead to a universe that ends with either LR or LSBR. Based on a modified Wheeler-DeWitt equation, we demonstrate that such fatal endings seems to be avoidable.
Chandrasekhar limit: an elementary approach based on classical physics and quantum theory
NASA Astrophysics Data System (ADS)
Pinochet, Jorge; Van Sint Jan, Michael
2016-05-01
In a brief article published in 1931, Subrahmanyan Chandrasekhar made public an important astronomical discovery. In his article, the then young Indian astrophysicist introduced what is now known as the Chandrasekhar limit. This limit establishes the maximum mass of a stellar remnant beyond which the repulsion force between electrons due to the exclusion principle can no longer stop the gravitational collapse. In the present article, we create an elemental approximation to the Chandrasekhar limit, accessible to non-graduate science and engineering students. The article focuses especially on clarifying the origins of Chandrasekhar’s discovery and the underlying physical concepts. Throughout the article, only basic algebra is used as well as some general notions of classical physics and quantum theory.
A Unified Approach to Conformational Statistics of Classical Polymer and Polypeptide Models
Kim, Jin Seob; Chirikjian, Gregory S.
2010-01-01
We present a unified method to generate conformational statistics which can be applied to any of the classical discrete-chain polymer models. The proposed method employs the concepts of Fourier transform and generalized convolution for the group of rigid-body motions in order to obtain probability density functions of chain end-to-end distance. In this paper, we demonstrate the proposed method with three different cases: the freely-rotating model, independent energy model, and interdependent pairwise energy model (the last two are also well-known as the Rotational Isomeric State model). As for numerical examples, for simplicity, we assume homogeneous polymer chains. For the freely-rotating model, we verify the proposed method by comparing with well-known closed-form results for mean-squared end-to-end distance. In the interdependent pairwise energy case, we take polypeptide chains such as polyalanine and polyvaline as examples. PMID:20165562
A new approach to the classical and quantum dynamics of branes
NASA Astrophysics Data System (ADS)
Pavšič, Matej
2016-07-01
It is shown that the Dirac-Nambu-Goto brane can be described as a point particle in an infinite-dimensional brane space with a particular metric. This suggests a generalization to brane spaces with arbitrary metric, including the “flat” metric. Then quantization of such a system is straightforward: it is just like quantization of a bunch of noninteracting particles. This leads us to a system of a continuous set of scalar fields. For a particular choice of the metric in the space of fields we find that the classical Dirac-Nambu-Goto brane theory arises as an effective theory of such an underlying quantum field theory. Quantization of branes is important for the brane world scenarios, and thus for “quantum gravity.”
Benassi, Filippo; Manca, Tullio; Ramelli, Andrea; Vezzani, Antonella; Nicolini, Francesco; Romano, Giorgio; Ricci, Matteo; Carino, Davide; Di Chicco, Maria Vincenza; Gherli, Tiziano
2016-01-01
Background The aim of our study is to compare the classical surgical tracheostomy (TT) technique with a modified surgical technique designed and created by the cardiothoracic surgery staff of our department to reduce surgical trauma and postoperative complications. This modified technique combines features of percutaneous TT and surgical TT avoiding the use of specialized tools, which are required in percutaneous TT. Methods From October 2008 to March 2014 we performed 67 tracheostomies using this New Modified Surgical Technique (NMST) and 56 TT with the Classical Surgical Technique (CST). We collected data about the early clinical complications, deaths TT-related, deaths due to other complications and the presence of late TT’s complications were performed by a telephone follow-up. SPSS software (IMB version 21) was used for the statistical analysis. Categorical data were treated with chi-square test and continuous data were treated with t-test for independent samples. Results NMST group had a significant lower number of early complications (P=0.005) compared to CST group (5 vs. 15). In-hospital mortality was significantly higher in CST group (18 deaths vs. 4 in NMST group, P=0.001) but we registered only one case of TT-related mortality in CST group (P=0.280). We did not note other differences between the two groups regarding short or mid-long term complications. Conclusions In our experience the NMST demonstrated to be easily safe and reproducible with an amount of early, mid- and long-term complications similar to the CST; furthermore the aesthetic results of the procedure appear similar to those of percutaneous TT. PMID:28149558
Fragmentation of positronium in collision with He atoms: A classical theoretical approach
Sarkadi, L.
2003-09-01
The classical trajectory Monte Carlo method was applied to the description of the fragmentation of the positronium (Ps) in collision with He atoms. The collision system was simplified to a three-body system consisting of the electron and the positron of the Ps, as well as the He atom that was considered as a structureless particle. The interaction of the e{sup -} and e{sup +} with the He was approximated by a static, fully screened Coulomb potential. The calculations were carried out for collision energies 13, 18, 25, and 33 eV. The obtained total break-up cross sections and the longitudinal energy distributions of the emitted positrons were compared with the recent experimental results of Armitage et al. [Phys. Rev. Lett. 89, 173402 (2002)]. The present theory overestimates the measured cross sections by a factor of 1.6-2.5, but it correctly reproduces the peak found by Armitage et al. in the positron spectra at about half of the residual Ps energy.
Eyeblink Classical Conditioning and Post-Traumatic Stress Disorder – A Model Systems Approach
Schreurs, Bernard G.; Burhans, Lauren B.
2015-01-01
Not everyone exposed to trauma suffers flashbacks, bad dreams, numbing, fear, anxiety, sleeplessness, hyper-vigilance, hyperarousal, or an inability to cope, but those who do may suffer from post-traumatic stress disorder (PTSD). PTSD is a major physical and mental health problem for military personnel and civilians exposed to trauma. There is still debate about the incidence and prevalence of PTSD especially among the military, but for those who are diagnosed, behavioral therapy and drug treatment strategies have proven to be less than effective. A number of these treatment strategies are based on rodent fear conditioning research and are capable of treating only some of the symptoms because the extinction of fear does not deal with the various forms of hyper-vigilance and hyperarousal experienced by people with PTSD. To help address this problem, we have developed a preclinical eyeblink classical conditioning model of PTSD in which conditioning and hyperarousal can both be extinguished. We review this model and discuss findings showing that unpaired stimulus presentations can be effective in reducing levels of conditioning and hyperarousal even when unconditioned stimulus intensity is reduced to the point where it is barely capable of eliciting a response. These procedures have direct implications for the treatment of PTSD and could be implemented in a virtual reality environment. PMID:25904874
NASA Astrophysics Data System (ADS)
Niquet, Yann-Michel; Nguyen, Viet-Hung; Triozon, François; Duchemin, Ivan; Nier, Olivier; Rideau, Denis
2014-02-01
We discuss carrier mobilities in the quantum Non-Equilibrium Green's Functions (NEGF) framework. We introduce a method for the extraction of the mobility that is free from contact resistance contamination and with minimal needs for ensemble averages. We focus on silicon thin films as an illustration, although the method can be applied to various materials such as semiconductor nanowires or carbon nanostructures. We then introduce a new paradigm for the definition of the partial mobility μM associated with a given elastic scattering mechanism "M," taking phonons (PH) as a reference (μM-1=μPH+M-1-μPH-1). We argue that this definition makes better sense in a quantum transport framework as it is free from long range interference effects that can appear in purely ballistic calculations. As a matter of fact, these mobilities satisfy Matthiessen's rule for three mechanisms [e.g., surface roughness (SR), remote Coulomb scattering (RCS) and phonons] much better than the usual, single mechanism calculations. We also discuss the problems raised by the long range spatial correlations in the RCS disorder. Finally, we compare semi-classical Kubo-Greenwood (KG) and quantum NEGF calculations. We show that KG and NEGF are in reasonable agreement for phonon and RCS, yet not for SR. We discuss the reasons for these discrepancies.
Niquet, Yann-Michel Nguyen, Viet-Hung; Duchemin, Ivan; Nier, Olivier; Rideau, Denis
2014-02-07
We discuss carrier mobilities in the quantum Non-Equilibrium Green's Functions (NEGF) framework. We introduce a method for the extraction of the mobility that is free from contact resistance contamination and with minimal needs for ensemble averages. We focus on silicon thin films as an illustration, although the method can be applied to various materials such as semiconductor nanowires or carbon nanostructures. We then introduce a new paradigm for the definition of the partial mobility μ{sub M} associated with a given elastic scattering mechanism “M,” taking phonons (PH) as a reference (μ{sub M}{sup −1}=μ{sub PH+M}{sup −1}−μ{sub PH}{sup −1}). We argue that this definition makes better sense in a quantum transport framework as it is free from long range interference effects that can appear in purely ballistic calculations. As a matter of fact, these mobilities satisfy Matthiessen's rule for three mechanisms [e.g., surface roughness (SR), remote Coulomb scattering (RCS) and phonons] much better than the usual, single mechanism calculations. We also discuss the problems raised by the long range spatial correlations in the RCS disorder. Finally, we compare semi-classical Kubo-Greenwood (KG) and quantum NEGF calculations. We show that KG and NEGF are in reasonable agreement for phonon and RCS, yet not for SR. We discuss the reasons for these discrepancies.
Eyeblink classical conditioning and post-traumatic stress disorder - a model systems approach.
Schreurs, Bernard G; Burhans, Lauren B
2015-01-01
Not everyone exposed to trauma suffers flashbacks, bad dreams, numbing, fear, anxiety, sleeplessness, hyper-vigilance, hyperarousal, or an inability to cope, but those who do may suffer from post-traumatic stress disorder (PTSD). PTSD is a major physical and mental health problem for military personnel and civilians exposed to trauma. There is still debate about the incidence and prevalence of PTSD especially among the military, but for those who are diagnosed, behavioral therapy and drug treatment strategies have proven to be less than effective. A number of these treatment strategies are based on rodent fear conditioning research and are capable of treating only some of the symptoms because the extinction of fear does not deal with the various forms of hyper-vigilance and hyperarousal experienced by people with PTSD. To help address this problem, we have developed a preclinical eyeblink classical conditioning model of PTSD in which conditioning and hyperarousal can both be extinguished. We review this model and discuss findings showing that unpaired stimulus presentations can be effective in reducing levels of conditioning and hyperarousal even when unconditioned stimulus intensity is reduced to the point where it is barely capable of eliciting a response. These procedures have direct implications for the treatment of PTSD and could be implemented in a virtual reality environment.
Amigo, José Manuel; Ravn, Carsten; Gallagher, Neal B; Bro, Rasmus
2009-05-21
In hyperspectral analysis, PLS-discriminant analysis (PLS-DA) is being increasingly used in conjunction with pure spectra where it is often referred to as PLS-Classification (PLS-Class). PLS-Class has been presented as a novel approach making it possible to obtain qualitative information about the distribution of the compounds in each pixel using little a priori knowledge about the image (only the pure spectrum of each compound is needed). In this short note it is shown that the PLS-Class model is the same as a straightforward classical least squares (CLS) model and it is highlighted that it is more appropriate to view this approach as CLS rather than PLS-DA. A real example illustrates the results of applying both PLS-Class and CLS.
Suh, Young Chul; Choi, Jong-Woo; Oh, Tae Suk; Koh, Kyung S
2016-11-01
Although the subcilliary or conventional transconjunctival approach has been widely used, it often fails to get acceptable visual fields or scars. This study directly compared the extended transconjunctival approach accompanied by lateral paracanthal incision with other traditional approaches in terms of surgical fields, the outcomes and complications. This retrospective chart review included 113 patients (82 males and 31 females; mean age: 38.7 years; range: 11-87 years), who underwent orbital reduction from November 2009 to September 2013. In extended transconjunctival approach, the external skin of the inferolateral canthal tendon was demarcated in a natural skin crease approximately 5 mm from the lateral canthus. The surgical approach was based on anteroseptal transconjunctival dissection. Paracanthal incision about 5 mm in length was performed. Esthetic and functional complications were evaluated, including the presence of a visible scar, lid retraction, or hypertrophic scar; epiphora, diplopia, global hematoma, persistent enophthamos, or exophthamos; and presence of entropion/ectropion. The extended transconjunctival approach resulted in a significant increase in the area of the surgical field statistically significant (P = 0.002). Complication rates are similar with other approach techniques. Postoperative scarring was confirmed by pictures taken in the outpatient clinic. The physicians' average Vancouver scar scale (VSS) of first physician was 1.26 and second physician was 1.2. Compared with the conventional transconjunctival approach, the extended transconjunctival approach with paracanthal incision had similar complication and scarring rates, as well as a lower scarring rate than the subciliary approach while providing much wider surgical fields.
NASA Astrophysics Data System (ADS)
Puzari, Panchanan; Sarkar, Biplab; Adhikari, Satrajit
2006-11-01
We investigate the molecular dynamics of pyrazine after excitation to the S2 electronic state by using the time-dependent discrete variable representation (TDDVR) method. The investigation has been carried out with a realistic 24-mode model Hamiltonian consisting of all the vibrational degrees of freedom of pyrazine molecule. First, we perform the simulation on a basic four-mode model, and then by including additional eight important modes and finally, by introducing 20 bath modes on the basic model. This sequential inclusion of bath modes demonstrates the effect of weak modes on the subsystem, where the calculations of energy and population transfer from basic model to the bath quantify the same effect. The spectral profile obtained by using TDDVR approach shows reasonably good agreement with the results calculated by quantum mechanical approach. It appears that the TDDVR approach for those large systems where quantum mechanical description is needed in a restricted region is a good compromise between accuracy and speed.
Puzari, Panchanan; Sarkar, Biplab; Adhikari, Satrajit
2006-11-21
We investigate the molecular dynamics of pyrazine after excitation to the S2 electronic state by using the time-dependent discrete variable representation (TDDVR) method. The investigation has been carried out with a realistic 24-mode model Hamiltonian consisting of all the vibrational degrees of freedom of pyrazine molecule. First, we perform the simulation on a basic four-mode model, and then by including additional eight important modes and finally, by introducing 20 bath modes on the basic model. This sequential inclusion of bath modes demonstrates the effect of weak modes on the subsystem, where the calculations of energy and population transfer from basic model to the bath quantify the same effect. The spectral profile obtained by using TDDVR approach shows reasonably good agreement with the results calculated by quantum mechanical approach. It appears that the TDDVR approach for those large systems where quantum mechanical description is needed in a restricted region is a good compromise between accuracy and speed.
Evans, Deborah J; Owlarn, Suthira; Tejada Romero, Belen; Chen, Chen; Aboobaker, A Aziz
2011-01-01
The current model of planarian anterior regeneration evokes the establishment of low levels of Wnt signalling at anterior wounds, promoting anterior polarity and subsequent elaboration of anterior fate through the action of the TALE class homeodomain PREP. The classical observation that decapitations positioned anteriorly will regenerate heads more rapidly than posteriorly positioned decapitations was among the first to lead to the proposal of gradients along an anteroposterior (AP) axis in a developmental context. An explicit understanding of this phenomenon is not included in the current model of anterior regeneration. This raises the question what the underlying molecular and cellular basis of this temporal gradient is, whether it can be explained by current models and whether understanding the gradient will shed light on regenerative events. Differences in anterior regeneration rate are established very early after amputation and this gradient is dependent on the activity of Hedgehog (Hh) signalling. Animals induced to produce two tails by either Smed-APC-1(RNAi) or Smed-ptc(RNAi) lose anterior fate but form previously described ectopic anterior brain structures. Later these animals form peri-pharyngeal brain structures, which in Smed-ptc(RNAi) grow out of the body establishing a new A/P axis. Combining double amputation and hydroxyurea treatment with RNAi experiments indicates that early ectopic brain structures are formed by uncommitted stem cells that have progressed through S-phase of the cell cycle at the time of amputation. Our results elaborate on the current simplistic model of both AP axis and brain regeneration. We find evidence of a gradient of hedgehog signalling that promotes posterior fate and temporarily inhibits anterior regeneration. Our data supports a model for anterior brain regeneration with distinct early and later phases of regeneration. Together these insights start to delineate the interplay between discrete existing, new, and then
Evans, Deborah J.; Owlarn, Suthira; Tejada Romero, Belen; Chen, Chen; Aboobaker, A. Aziz
2011-01-01
The current model of planarian anterior regeneration evokes the establishment of low levels of Wnt signalling at anterior wounds, promoting anterior polarity and subsequent elaboration of anterior fate through the action of the TALE class homeodomain PREP. The classical observation that decapitations positioned anteriorly will regenerate heads more rapidly than posteriorly positioned decapitations was among the first to lead to the proposal of gradients along an anteroposterior (AP) axis in a developmental context. An explicit understanding of this phenomenon is not included in the current model of anterior regeneration. This raises the question what the underlying molecular and cellular basis of this temporal gradient is, whether it can be explained by current models and whether understanding the gradient will shed light on regenerative events. Differences in anterior regeneration rate are established very early after amputation and this gradient is dependent on the activity of Hedgehog (Hh) signalling. Animals induced to produce two tails by either Smed-APC-1(RNAi) or Smed-ptc(RNAi) lose anterior fate but form previously described ectopic anterior brain structures. Later these animals form peri-pharyngeal brain structures, which in Smed-ptc(RNAi) grow out of the body establishing a new A/P axis. Combining double amputation and hydroxyurea treatment with RNAi experiments indicates that early ectopic brain structures are formed by uncommitted stem cells that have progressed through S-phase of the cell cycle at the time of amputation. Our results elaborate on the current simplistic model of both AP axis and brain regeneration. We find evidence of a gradient of hedgehog signalling that promotes posterior fate and temporarily inhibits anterior regeneration. Our data supports a model for anterior brain regeneration with distinct early and later phases of regeneration. Together these insights start to delineate the interplay between discrete existing, new, and then
Evaluating the Health Impact of Large-Scale Public Policy Changes: Classical and Novel Approaches.
Basu, Sanjay; Meghani, Ankita; Siddiqi, Arjumand
2017-03-20
Large-scale public policy changes are often recommended to improve public health. Despite varying widely-from tobacco taxes to poverty-relief programs-such policies present a common dilemma to public health researchers: how to evaluate their health effects when randomized controlled trials are not possible. Here, we review the state of knowledge and experience of public health researchers who rigorously evaluate the health consequences of large-scale public policy changes. We organize our discussion by detailing approaches to address three common challenges of conducting policy evaluations: distinguishing a policy effect from time trends in health outcomes or preexisting differences between policy-affected and -unaffected communities (using difference-in-differences approaches); constructing a comparison population when a policy affects a population for whom a well-matched comparator is not immediately available (using propensity score or synthetic control approaches); and addressing unobserved confounders by utilizing quasi-random variations in policy exposure (using regression discontinuity, instrumental variables, or near-far matching approaches).
Jo, Youn Yi; Choi, Eunkyeong
2011-01-01
Background During transurethral resection of bladder tumors (TURB) under spinal anesthesia, electrical resection of the lateral wall mass may cause violent adductor contraction and possible inadvertent bladder perforation. Therefore, obturator nerve block (ONB) is mandatory after spinal anesthesia to avoid adductor muscle contraction. We compared the success rate and efficacy of an inguinal approach, to a pubic approach for ONB. Methods One hundred and two patients who required ONB undergoing TURB with spinal anesthesia were included in this study. After spinal anesthesia, ONB was performed with an inguinal approach (Group I, n = 51) or pubic approach (Group P, n = 51) using a nerve stimulator. In the pubic approach, a needle was inserted at a point 1.5 cm lateral and 1.5 cm inferior to the pubic tubercle. For the inguinal approach, a needle was inserted at the midpoint of the femoral artery and the inner margin of the adductor longus muscle 0.5 cm below the inguinal crease. If the adductor contracture had not occurred by the 3rd attempt, it was defined as a failed block. Puncture frequency, success rate, anatomical characteristics, and the presence of adductor muscle contraction during operation were evaluated. Results The success rate of ONB was higher in group I compared to group P (96.1% vs. 84.0%, P = 0.046) and the frequency of needle attempts was lower in group I than in group P (1.8 ± 0.9 vs. 1.3 ± 0.6, P = 0.01). Conclusions The inguinal approach for ONB appears to be technically easier and offers certain anatomical advantages when compared to the pubic approach. PMID:21927685
Nissen, Felix; Keeling, Jonathan
2010-06-15
We apply a many-body Wentzel-Kramers-Brillouin (WKB) approach to determine the leading quantum corrections to the semiclassical dynamics of the Josephson model, describing interacting bosons able to tunnel between two localized states. The semiclassical dynamics is known to divide between regular oscillations and self-trapped oscillations where the sign of the imbalance remains fixed. In both cases, the WKB wave functions are matched to Airy functions, yielding a modified Bohr-Sommerfeld quantization condition. At the critical energy dividing normal and self-trapped oscillations, the WKB wave functions should instead be matched to parabolic cylinder functions, leading to a quantization formula that is not just the Bohr-Sommerfeld formula, and recovering the known logarithmic quantum break times at this energy. This work thus provides another illustration of the usefulness of the WKB approach in certain many-body problems.
NASA Astrophysics Data System (ADS)
Sakko, Arto; Rossi, Tuomas P.; Nieminen, Risto M.
2014-08-01
The presence of plasmonic material influences the optical properties of nearby molecules in untrivial ways due to the dynamical plasmon-molecule coupling. We combine quantum and classical calculation schemes to study this phenomenon in a hybrid system that consists of a Na2 molecule located in the gap between two Au/Ag nanoparticles. The molecule is treated quantum-mechanically with time-dependent density-functional theory, and the nanoparticles with quasistatic classical electrodynamics. The nanoparticle dimer has a plasmon resonance in the visible part of the electromagnetic spectrum, and the Na2 molecule has an electron-hole excitation in the same energy range. Due to the dynamical interaction of the two subsystems the plasmon and the molecular excitations couple, creating a hybridized molecular-plasmon excited state. This state has unique properties that yield e.g. enhanced photoabsorption compared to the freestanding Na2 molecule. The computational approach used enables decoupling of the mutual plasmon-molecule interaction, and our analysis verifies that it is not legitimate to neglect the backcoupling effect when describing the dynamical interaction between plasmonic material and nearby molecules. Time-resolved analysis shows nearly instantaneous formation of the coupled state, and provides an intuitive picture of the underlying physics.
Report on noninvasive prenatal testing: classical and alternative approaches.
Pantiukh, Kateryna S; Chekanov, Nikolay N; Zaigrin, Igor V; Zotov, Alexei M; Mazur, Alexander M; Prokhortchouk, Egor B
2016-01-01
Concerns of traditional prenatal aneuploidy testing methods, such as low accuracy of noninvasive and health risks associated with invasive procedures, were overcome with the introduction of novel noninvasive methods based on genetics (NIPT). These were rapidly adopted into clinical practice in many countries after a series of successful trials of various independent submethods. Here we present results of own NIPT trial carried out in Moscow, Russia. 1012 samples were subjected to the method aimed at measuring chromosome coverage by massive parallel sequencing. Two alternative approaches are ascertained: one based on maternal/fetal differential methylation and another based on allelic difference. While the former failed to provide stable results, the latter was found to be promising and worthy of conducting a large-scale trial. One critical point in any NIPT approach is the determination of fetal cell-free DNA fraction, which dictates the reliability of obtained results for a given sample. We show that two different chromosome Y representation measures-by real-time PCR and by whole-genome massive parallel sequencing-are practically interchangeable (r=0.94). We also propose a novel method based on maternal/fetal allelic difference which is applicable in pregnancies with fetuses of either sex. Even in its pilot form it correlates well with chromosome Y coverage estimates (r=0.74) and can be further improved by increasing the number of polymorphisms.
Thermodynamic Perturbation Approach to Freezing of the Classical One-Component Plasma
NASA Astrophysics Data System (ADS)
Hasegawa, Masayuki
1995-11-01
Systematic investigations are made of the thermodynamic perturbationapproach to freezing, which has proved successful for systemsinteracting through soft-core or long-ranged potentials. The classicalone-component plasma (OCP) is taken as the extreme case of suchsystems and the investigations focus on the reference systems employedin this approach and on the approximation schemes used to treat thatsystem. It is confirmed that good results are obtained for thefreezing properties of the OCP if a system with repulsive,short-ranged potential is properly chosen as the reference system, andboth this system and the remaining part due to the long-rangeinteraction are separately treated by the modified weighted-densityapproximation (MWDA) using accurate input data. However, if we adoptthe hard spheres as the reference system in this approach and useeither the MWDA or the generalized effective-liquid approximation(GELA) for this system, we cannot get similar results unless we usethe input data in the Percus-Yevick (PY) approximation rather than thevirtually \\lq\\lqexact” ones. This unfavorable result throwsserious doubt on the usefulness of the hard spheres as the referencesystem.
Bisi, A; Gobbi, S; Belluti, F; Rampa, A
2013-01-01
Cardiovascular disease represents the main cause of death worldwide. Novel therapies to reduce elevated blood pressure and treat resistant hypertension, to consequently reduce the associated cardiovascular risk factors, are still required. Among the different strategies commonly used in medicinal chemistry to develop new molecules, the synthesis of multitarget/hybrid compounds combining two or more pharmacophore groups targeting simultaneously selected factors involved in cardiovascular diseases, has gained increasing interest. This review will focus on the most recent literature on multifunctional cardiovascular drugs, paying particular attention on hybrid compounds bearing natural scaffolds, considering that compounds derived from medicinal extracts are generally appealing for the medicinal chemist as they often bear the so-called "privileged structures". Moreover, taking into account many excellent reviews dealing with multitarget cardiovascular drugs published in the last few years, mainly devoted to RAAS inhibition and/or NO donors hybrid drugs, herein the most significant results obtained and the benefits and limitations of these approaches will be highlighted.
Statistical dynamics of classical systems: A self-consistent field approach
Grzetic, Douglas J. Wickham, Robert A.; Shi, An-Chang
2014-06-28
We develop a self-consistent field theory for particle dynamics by extremizing the functional integral representation of a microscopic Langevin equation with respect to the collective fields. Although our approach is general, here we formulate it in the context of polymer dynamics to highlight satisfying formal analogies with equilibrium self-consistent field theory. An exact treatment of the dynamics of a single chain in a mean force field emerges naturally via a functional Smoluchowski equation, while the time-dependent monomer density and mean force field are determined self-consistently. As a simple initial demonstration of the theory, leaving an application to polymer dynamics for future work, we examine the dynamics of trapped interacting Brownian particles. For binary particle mixtures, we observe the kinetics of phase separation.
NASA Astrophysics Data System (ADS)
Wishart, D. N.
2014-12-01
An integrated approach incorporating multicomponent and classical solute geothermometry was used to evaluate its utility to estimate the temperature of the Bath geothermal reservoir, a low-enthalpy system on the island of Jamaica. Reservoir temperatures were estimated from (1) empirical geothermometric equations; (2) simulations of solute geothermometers using SolGeo software; (3) computations of saturation indices [Log(Q/K)] of reservoir minerals from full chemically-analyzed thermal water samples over a temperature range of 25-220°C in PHREEQC; and (4) the Giggenbach Na-K-Mg geothermometer. A principal component analysis (PCA) shows strong, positive correlations between Na+, K+, and Mg2+ and is regarded as significant for these ions in their reliance as useful reservoir geoindicators. However, a negative correlation exists between Na+, K+, Mg2+ and silica (SiO2). The more realistic estimates of the geothermal reservoir temperature were provided by the Na-K and Na-K-Mg geothermometers, whereas the Na-K-Ca geothermometer overestimated reservoir temperatures. Estimated geotemperatures from silica-quartz geothermometers were the lowest. The discrepancy in estimated geotemperatures may be due to processes such as boiling, degassing, dilution, rock dissolution, and mixing during the ascent of geothermal fluids. Log (Q/K) curves cluster over a range of equilibrium temperatures closest to Na-K and Na-K-Mg geothermometers at 80-102°C. Reservoir temperatures estimated for the Bath geothermal system range between 79-118°C. Comparisons of the estimated geotemperatures using the integrated approach to geothermometry show a favorable agreement. Based on the results of this investigation, the integrated geothermometric approach provided a more reliable approach to reconstruct the fluid composition at depth and estimate the geothermal reservoir temperature.
NASA Astrophysics Data System (ADS)
Bondarenko, S.; Lipatov, L.; Prygarin, A.
2017-08-01
We discuss application of formalism of small- x effective action for reggeized gluons (Gribov, Sov. Phys. JETP 26:414, 1968; Lipatov, Nucl. Phys. B 452:369, 1995; Lipatov, Phys. Rep. 286:131, 1997; Lipatov, Subnucl. Ser. 49:131, 2013; Lipatov, Int. J. Mod. Phys. Conf. Ser. 39:1560082, 2015; Lipatov, Int. J. Mod. Phys. A 31(28/29):1645011, 2016; Lipatov, EPJ Web Conf. 125:01010, 2016; Lipatov, Sov. J. Nucl. Phys. 23:338, 1976; Kuraev et al., Sov. Phys. JETP 45:199, 1977; Kuraev et al., Zh Eksp, Teor. Fiz. 72:377, 1977; Balitsky and Lipatov, Sov. J. Nucl. Phys. 28:822, 1978; Balitsky and Lipatov, Yad. Fiz. 28:1597 1978), for the calculation of classical gluon field of relativistic color charge, similarly to that done in CGC approach of McLerran and Venugopalan, Phys. Rev. D 49:2233 (1994), Jalilian-Marian et al., Phys. Rev. D 55:5414 (1997), Jalilian-Marian et al., Nucl. Phys. B 504:415 (1997), Jalilian-Marian et al., Phys. Rev. D 59:014014 (1998), Jalilian-Marian et al., Phys. Rev. D 59:014015 (1998), Iancu et al., Nucl. Phys. A 692:583 (2001), Iancu et al., Phys. Lett. B 510:133 (2001), Ferreiro et al., Nucl. Phys. A 703:489 (2002). The equations of motion with the reggeon fields are solved in LO and NLO approximations and new solutions are found. The results are compared to the calculations performed in the CGC framework and it is demonstrated that the LO CGC results for the classical field are reproduced in our calculations. Possible applications of the NLO solution in the effective action and CGC frameworks are discussed as well.
Schulz, Katja; Calba, Clémentine; Peyre, Marisa; Staubach, Christoph; Conraths, Franz J
2016-09-06
Surveillance measures can only be effective if key players in the system accept them. Acceptability, which describes the willingness of persons to contribute, is often analyzed using participatory methods. Participatory epidemiology enables the active involvement of key players in the assessment of epidemiological issues. In the present study, we used a participatory method recently developed by CIRAD (Centre de Coopération Internationale en Recherche Agronomique pour le Développement) to evaluate the functionality and acceptability of Classical Swine Fever (CSF) surveillance in wild boar in Germany, which is highly dependent on the participation of hunters. The acceptability of alternative surveillance strategies was also analyzed. By conducting focus group discussions, potential vulnerabilities in the system were detected and feasible alternative surveillance strategies identified. Trust in the current surveillance system is high, whereas the acceptability of the operation of the system is medium. Analysis of the acceptability of alternative surveillance strategies showed how risk-based surveillance approaches can be combined to develop strategies that have sufficient support and functionality. Furthermore, some surveillance strategies were clearly rejected by the hunters. Thus, the implementation of such strategies may be difficult. Participatory methods can be used to evaluate the functionality and acceptability of existing surveillance plans for CSF among hunters and to optimize plans regarding their chances of successful implementation.
NASA Astrophysics Data System (ADS)
Makino, Hironori; Minami, Nariyuki
2014-07-01
The theory of the quantal level statistics of a classically integrable system, developed by Makino et al. in order to investigate the non-Poissonian behaviors of level-spacing distribution (LSD) and level-number variance (LNV) [H. Makino and S. Tasaki, Phys. Rev. E 67, 066205 (2003); H. Makino and S. Tasaki, Prog. Theor. Phys. Suppl. 150, 376 (2003); H. Makino, N. Minami, and S. Tasaki, Phys. Rev. E 79, 036201 (2009); H. Makino and S. Tasaki, Prog. Theor. Phys. 114, 929 (2005)], is successfully extended to the study of the E(K,L) function, which constitutes a fundamental measure to determine most statistical observables of quantal levels in addition to LSD and LNV. In the theory of Makino et al., the eigenenergy level is regarded as a superposition of infinitely many components whose formation is supported by the Berry-Robnik approach in the far semiclassical limit [M. Robnik, Nonlinear Phenom. Complex Syst. 1, 1 (1998)]. We derive the limiting E(K,L) function in the limit of infinitely many components and elucidate its properties when energy levels show deviations from the Poisson statistics.
Tedesco, Daniele; Bertucci, Carlo
2015-09-10
Induced circular dichroism (ICD) is a spectroscopic phenomenon that provides versatile and useful methods for characterizing the structural and dynamic properties of the binding of drugs to target proteins. The understanding of biorecognition processes at the molecular level is essential to discover and validate new pharmacological targets, and to design and develop new potent and selective drugs. The present article reviews the main applications of ICD to drug binding studies on serum carrier proteins, going from the classic approaches for the derivation of drug binding parameters and the identification of binding sites, to an overview of the emerging trends for the characterization of binding modes by means of quantum chemical (QC) techniques. The advantages and limits of the ICD methods for the determination of binding parameters are critically reviewed; the capability to investigate the binding interactions of drugs and metabolites to their target proteins is also underlined, as well as the possibility of characterizing the binding sites to obtain a complete picture of the binding mechanism and dynamics. The new applications of ICD methods to identify stereoselective binding modes of drug/protein complexes are then reviewed with relevant examples. The combined application of experimental ICD spectroscopy and QC calculations is shown to identify qualitatively the bound conformations of ligands to target proteins even in the absence of a detailed structure of the binding sites, either obtained from experimental X-ray crystallography and NMR measurements or from computational models of the complex. Copyright © 2015 Elsevier B.V. All rights reserved.
NASA Astrophysics Data System (ADS)
Trahan, Corey J.; Wyatt, Robert E.
2003-10-01
Recently, Donoso and Martens described a method for evolving both classical and quantum phase-space distribution functions, W(q,p,t), that involves the propagation of an ensemble of correlated trajectories. The trajectories are linked into a unified whole by spatial and momentum derivatives of density dependent terms in the equations of motion. On each time step, these nonlocal terms were evaluated by fitting the density around each trajectory to an assumed functional form. In the present study, we develop a different trajectory method for propagating phase-space distribution functions. A hierarchy of coupled analytic equations of motion are derived for the q and p derivatives of the density and a truncated set of these are integrated along each trajectory concurrently with the equation of motion for the density. The advantage of this approach is that individual trajectories can be propagated, one at a time, and function fitting is not required to evaluate the nonlocal terms. Regional nonlocality can be incorporated at various levels of approximation to "dress" what would otherwise be "thin" locally propagating trajectories. This derivative propagation method is used to obtain trajectory solutions for the Klein-Kramers equation, the Husimi equation, and for a smoothed version of the Caldeira-Leggett equation derived by the Diosi. Trajectory solutions are obtained for the relaxation of an oscillator in contact with a thermal bath and for the decay of a metastable state.
Vyumvuhore, R; Tfayli, A; Manfait, M; Baillet-Guffroy, A
2014-08-01
Skin dryness is an omnipresent symptom in various types of skin disorders. Thereby, a large panel of skin care products is developed for therapeutic purposes. However, there is still a lack of non-invasive methods to determine the mechanisms of action of moisturizers at the molecular level. In the present study, confocal Raman spectroscopy coupled to classical least square analyses and ATR-FTIR were used to investigate the effect of different molecules on the stratum corneum (SC) hydration degree and barrier state. First, hygroscopic property was determined by analyzing samples at 90% RH; secondly, the water barrier function was evaluated after the dehydration process (4% RH). The molecules penetration kinetics across SC were also studied for 2 h. Using the present approach, glycerin and propylene glycol were found to be humectants; lanoline showed occlusive action, lactic acid has both humectant and barrier enhancer properties, and ethylhexyl palmitate and caprylic/capric acid triglyceride seemed to be emollients. These observations are in accordance with literature. The present method non-invasively characterizes the mechanism of action of tested molecules. This may improve knowledge of new molecules' structure-activity relationship and help make an effective therapeutic concept dealing with the various skin dysfunctions. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
NASA Astrophysics Data System (ADS)
Rey, Angel M.; Román-Roy, Narciso; Salgado, Modesto
2005-05-01
The first aim of this paper is to extend the Skinner-Rusk formalism on classical mechanics for first-order field theories. The second is to generalize the definition and properties of the evolution K-operator on classical mechanics for first-order field theories using in both cases Günther's formalism (k-symplectic formalism).
Chen, Hanning; McMahon, J. M.; Ratner, Mark A.; Schatz, George C.
2010-09-02
A new multiscale computational methodology was developed to effectively incorporate the scattered electric field of a plasmonic nanoparticle into a quantum mechanical (QM) optical property calculation for a nearby dye molecule. For a given location of the dye molecule with respect to the nanoparticle, a frequency-dependent scattering response function was first determined by the classical electrodynamics (ED) finite-difference time-domain (FDTD) approach. Subsequently, the time-dependent scattered electric field at the dye molecule was calculated using the FDTD scattering response function through a multidimensional Fourier transform to reflect the effect of polarization of the nanoparticle on the local field at the molecule. Finally, a real-time time-dependent density function theory (RT-TDDFT) approach was employed to obtain a desired optical property (such as absorption cross section) of the dye molecule in the presence of the nanoparticle’s scattered electric field. Our hybrid QM/ED methodology was demonstrated by investigating the absorption spectrum of the N3 dye molecule and the Raman spectrum of pyridine, both of which were shown to be significantly enhanced by a 20 nm diameter silver sphere. In contrast to traditional quantum mechanical optical calculations in which the field at the molecule is entirely determined by intensity and polarization direction of the incident light, in this work we show that the light propagation direction as well as polarization and intensity are important to nanoparticle-bound dye molecule response. At no additional computation cost compared to conventional ED and QM calculations, this method provides a reliable way to couple the response of the dye molecule’s individual electrons to the collective dielectric response of the nanoparticle.
Stahnke, N; Liebscher, V; Staubach, C; Ziller, M
2013-11-01
The analysis of epidemiological field data from monitoring and surveillance systems (MOSSs) in wild animals is of great importance in order to evaluate the performance of such systems. By parameter estimation from MOSS data, conclusions about disease dynamics in the observed population can be drawn. To strengthen the analysis, the implementation of a maximum likelihood estimation is the main aim of our work. The new approach presented here is based on an underlying simple SIR (susceptible-infected-recovered) model for a disease scenario in a wildlife population. The three corresponding classes are assumed to govern the intensities (number of animals in the classes) of non-homogeneous Poisson processes. A sampling rate was defined which describes the process of data collection (for MOSSs). Further, the performance of the diagnostics was implemented in the model by a diagnostic matrix containing misclassification rates. Both descriptions of these MOSS parts were included in the Poisson process approach. For simulation studies, the combined model demonstrates its ability to validly estimate epidemiological parameters, such as the basic reproduction rate R0. These parameters will help the evaluation of existing disease control systems. They will also enable comparison with other simulation models. The model has been tested with data from a Classical Swine Fever (CSF) outbreak in wild boars (Sus scrofa scrofa L.) from a region of Germany (1999-2002). The results show that the hunting strategy as a sole control tool is insufficient to decrease the threshold for susceptible animals to eradicate the disease, since the estimated R0 confirms an ongoing epidemic of CSF. Copyright © 2013 Elsevier B.V. All rights reserved.
ERIC Educational Resources Information Center
Masciantonio, Rudolph
This is a teacher's guide for Level Beta of a humanistic approach to instruction of Classical Greek and Greek culture in secondary schools. The goals of the program are to help students become aware of: (1) the impact of Hellenic civilization on contemporary society, including the impact of the Greek language on English; (2) the similarities and…
ERIC Educational Resources Information Center
Masciantonio, Rudolph
This is a student's programmed text for Level Beta of a humanistic approach to instruction of Classical Greek and Greek culture in secondary schools. The goals of the program are to help students become aware of: (1) the impact of Hellenic civilization on contemporary society, including the impact of the Greek language on English; (2) the…
ERIC Educational Resources Information Center
Clayman, Dee L.
1995-01-01
Appraises several databases devoted to classical literature. Thesaurus Linguae Graecae (TLG) contains the entire extant corpus of ancient Greek literature, including works on lexicography and historiography, extending into the 15th century. Other works awaiting completion are the Database of Classical Bibliography and a CD-ROM pictorial dictionary…
NASA Astrophysics Data System (ADS)
Torrielli, Alessandro
2016-08-01
We review some essential aspects of classically integrable systems. The detailed outline of the sections consists of: 1. Introduction and motivation, with historical remarks; 2. Liouville theorem and action-angle variables, with examples (harmonic oscillator, Kepler problem); 3. Algebraic tools: Lax pairs, monodromy and transfer matrices, classical r-matrices and exchange relations, non-ultralocal Poisson brackets, with examples (non-linear Schrödinger model, principal chiral field); 4. Features of classical r-matrices: Belavin-Drinfeld theorems, analyticity properties, and lift of the classical structures to quantum groups; 5. Classical inverse scattering method to solve integrable differential equations: soliton solutions, spectral properties and the Gel’fand-Levitan-Marchenko equation, with examples (KdV equation, Sine-Gordon model). Prepared for the Durham Young Researchers Integrability School, organised by the GATIS network. This is part of a collection of lecture notes.
Dou, Wenjie; Subotnik, Joseph E
2016-01-14
A broadened classical master equation (BCME) is proposed for modeling nonadiabatic dynamics for molecules near metal surfaces over a wide range of parameter values and with arbitrary initial conditions. Compared with a standard classical master equation-which is valid in the limit of weak molecule-metal couplings-this BCME should be valid for both weak and strong molecule-metal couplings. (The BCME can be mapped to a Fokker-Planck equation that captures level broadening correctly.) Finally, our BCME can be solved with a simple surface hopping algorithm; numerical tests of equilibrium and dynamical observables look very promising.
ERIC Educational Resources Information Center
Kaisarevic, Sonja N.; Andric, Silvana A.; Kostic, Tatjana S.
2017-01-01
In response to the Bologna Declaration and contemporary trends in Animal Physiology education, the Animal Physiology course at the Faculty of Sciences, University of Novi Sad, Serbia, has evolved over a 12-year period (2001-2012): from a classical two-semester course toward a one-semester course utilizing computer simulations of animal…
Mavri, Janez; Liu, Hanbin; Olsson, Mats H M; Warshel, Arieh
2008-05-15
The ability of using wave function propagation approaches to simulate isotope effects in enzymes is explored, focusing on the large H/D kinetic isotope effect of soybean lipoxygenase-1 (SLO-1). The H/D kinetic isotope effect (KIE) is calculated as the ratio of the rate constants for hydrogen and deuterium transfer. The rate constants are calculated from the time course of the H and D nuclear wave functions. The propagations are done using one-dimensional proton potentials generated as sections from the full multidimensional surface of the reacting system in the protein. The sections are obtained during a classical empirical valence bond (EVB) molecular dynamics simulation of SLO-1. Since the propagations require an extremely long time for treating realistic activation barriers, it is essential to use an effective biasing approach. Thus, we develop here an approach that uses the classical quantum path (QCP) method to evaluate the quantum free energy change associated with the biasing potential. This approach provides an interesting alternative to full QCP simulations and to other current approaches for simulating isotope effects in proteins. In particular, this approach can be used to evaluate the quantum mechanical transmission factor or other dynamical effects, while still obtaining reliable quantized activation free energies due to the QCP correction.
Chen, Jing; Schooling, Catherine Mary; Johnston, Janice Mary; Hedley, Anthony Johnson; McGhee, Sarah Morag
2011-01-01
Chronic obstructive pulmonary disease (COPD) is a leading cause of death, particularly in developing countries. Little is known about the effects of economic development on COPD mortality, although economic development may potentially have positive and negative influences over the life course on COPD. We took advantage of a unique population whose rapid and recent economic development is marked by changes at clearly delineated and identifiable time points, and where few women smoke, to examine the effect of macro-level events on COPD mortality. We used Poisson regression to decompose sex-specific COPD mortality rates in Hong Kong from 1981 to 2005 into the effects of age, period and cohort. COPD mortality declined strongly over generations for people born from the early to mid 20th century, which was particularly evident for the first generation to grow up in a more economically developed environment for both sexes. Population wide COPD mortality decreased when air quality improved and increased with increasing air pollution. COPD mortality increased with age, particularly after menopause among women. Economic development may reduce vulnerability to COPD by reducing long-lasting insults to the respiratory system, such as infections, poor nutrition and indoor air pollution. However, some of these gains may be offset if economic development results in increasing air pollution or increasing smoking.
Attell, Brandon K
2017-01-01
Several longitudinal studies show that over time the American public has become more approving of euthanasia and suicide for terminally ill persons. Yet, these previous findings are limited because they derive from biased estimates of disaggregated hierarchical data. Using insights from life course sociological theory and cross-classified logistic regression models, I better account for this liberalization process by disentangling the age, period, and cohort effects that contribute to longitudinal changes in these attitudes. The results of the analysis point toward a continued liberalization of both attitudes over time, although the magnitude of change was greater for suicide compared with euthanasia. More fluctuation in the probability of supporting both measures was exhibited for the age and period effects over the cohort effects. In addition, age-based differences in supporting both measures were found between men and women and various religious affiliations.
Wilcox, A J; Skjaerven, R; Irgens, L M
1994-09-01
The hypothesis was tested that unfavorable social conditions are associated with poor perinatal survival through direct effects on pregnancy or, more indirectly, through effects on mothers born under such conditions. The occupation of Norway by Nazi Germany was used as a period of social hardship. Data from Norwegian vital statistics and the Medical Birth Registry were used to describe perinatal mortality during World War II and also a generation later, among babies born to mothers who had themselves been born during the war. Logistic regression was used to identify a possible cohort effect among mothers born in 1940 through 1944 compared with mothers born before or after that period. Harsh conditions in Norway during the occupation increased childhood mortality. However, perinatal mortality declined during that period. Likewise, no adverse effect was seen on the survival of babies born to mothers who had themselves been born during the war (odds ratio = 1.00; 95% confidence interval = 0.96, 1.04). We find no evidence that wartime conditions in Norway impaired perinatal survival, either directly or through an effect on women born during the war. These data underscore how little is known about the ways that social conditions influence perinatal mortality.
NASA Astrophysics Data System (ADS)
Bode, Michael F.; Evans, Aneurin
2008-04-01
Preface; 1. Novae - a historical perspective Hilmar W. Duerbeck; 2. Properties of novae: an overview Brian Warner; 3. The evolution of nova-producing binary stars Icko Iben, Jr and Masayuki Y. Fujimoto; 4. Thermonuclear processes S. Starrfield, C. Iliadis and W. R. Hix; 5. Nova atmospheres and winds P. H. Hauschildt; 6. Observational mysteries and theoretical challenges Jordi Jose and Steven N. Shore; 7. Radio emission from novae E. R. Seaquist and M. F. Bode; 8. Infrared studies of classical novae Robert D. Gehrz; 9. Optical and ultraviolet evolution Steven N. Shore; 10. X-ray emission from classical novae in outburst Joachim Krautter; 11. Gamma-rays from classical novae Margarita Hernanz; 12. Resolved nova remnants T. J. O'Brien and M. F. Bode; 13. Dust and molecules in nova environments A. Evans and J. M. C. Rawlings; 14. Extragalactic novae Allen Shafter; Index.
NASA Astrophysics Data System (ADS)
Bode, Michael F.; Evans, Aneurin
2012-07-01
Preface; 1. Novae - a historical perspective Hilmar W. Duerbeck; 2. Properties of novae: an overview Brian Warner; 3. The evolution of nova-producing binary stars Icko Iben, Jr and Masayuki Y. Fujimoto; 4. Thermonuclear processes S. Starrfield, C. Iliadis and W. R. Hix; 5. Nova atmospheres and winds P. H. Hauschildt; 6. Observational mysteries and theoretical challenges Jordi Jose and Steven N. Shore; 7. Radio emission from novae E. R. Seaquist and M. F. Bode; 8. Infrared studies of classical novae Robert D. Gehrz; 9. Optical and ultraviolet evolution Steven N. Shore; 10. X-ray emission from classical novae in outburst Joachim Krautter; 11. Gamma-rays from classical novae Margarita Hernanz; 12. Resolved nova remnants T. J. O'Brien and M. F. Bode; 13. Dust and molecules in nova environments A. Evans and J. M. C. Rawlings; 14. Extragalactic novae Allen Shafter; Index.
NASA Astrophysics Data System (ADS)
Tran, H. N.; Dao, D. D.; Incerti, S.; Bernal, M. A.; Karamitros, M.; Nhan Hao, T. V.; Dang, T. M.; Francis, Z.
2016-01-01
In this work, we present a derivation of cross sections for single ionization and electron capture processes within the Classical Trajectory Monte Carlo (CTMC) approach. Specifically, we have used a potential stemming from an ab initio calculation in Green et al.'s framework to describe the dynamics of the water molecule system. Proposing a modified version of the Classical Over-Barrier (COB) potential, we have found that a cut-off of roughly 28 a.u. on the initial distance of the projectile produced a reasonable accuracy. A global agreement has been obtained in our calculations compared to experimental and other theoretical results for C6+ ion energies ranging from 10 keV/u to 10 MeV/u.
Classical and quantum field-theoretical approach to the non-linear q-Klein-Gordon equation
NASA Astrophysics Data System (ADS)
Plastino, A.; Rocca, M. C.
2016-11-01
In the wake of efforts made Nobre and Rego-Monteiro in EPL, 97 (2012) 41001 and J. Math. Phys., 54 (2913) 103302, we extend them here by developing the conventional Lagrangian treatment of a classical field theory (FT) to the q-Klein-Gordon equation advanced in Phys. Rev. Lett., 106 (2011) 140601 and J. Math. Phys., 54 (2913) 103302 by the same authors, and the quantum theory corresponding to q=\\frac {3} {2} . This makes it possible to generate a putative conjecture regarding black matter. Our theory reduces to the usual FT for q→ 1 .
NASA Astrophysics Data System (ADS)
Arvind; Chaturvedi, S.; Mukunda, N.
2017-04-01
We examine a recent proposal to show the presence of nonlocal Pancharatnam type geometric phases in a quantum mechanical treatment of intensity interferometry measurements upon inclusion of polarizing elements in the setup. It is shown that a completely classical statistical treatment of such effects is adequate for practical purposes. Further we show that the phase angles that appear in the correlations, while at first sight appearing to resemble Pancharatnam phases in their mathematical structure, cannot actually be interpreted in that manner. We also describe a simpler Mach-Zehnder type setup where similar effects can be observed without use of the paraxial approximation.
NASA Astrophysics Data System (ADS)
Kholmetskii, A. L.; Missevitch, O. V.; Yarman, T.
2017-09-01
We carry out the classical analysis of spin-orbit coupling in hydrogen-like atoms, using the modern expressions for the force and energy of an electric/magnetic dipole in an electromagnetic field. We disclose a novel physical meaning of this effect and show that for a laboratory observer the energy of spin-orbit interaction is represented solely by the mechanical energy of the spinning electron (considered as a gyroscope) due to the Thomas precession of its spin. Concurrently we disclose some errors in the old and new publications on this subject.
NASA Astrophysics Data System (ADS)
Chow, Tai L.
1995-05-01
Bring Classical Mechanics To Life With a Realistic Software Simulation! You can enhance the thorough coverage of Chow's Classical Mechanics with a hands-on, real-world experience! John Wiley & Sons, Inc. is proud to announce a new computer simulation for classical mechanics. Developed by the Consortium for Upper-Level Physics Software (CUPS), this simulation offers complex, often realistic calculations of models of various physical systems. Classical Mechanics Simulations (54881-2) is the perfect complement to Chow's text. Like all of the CUPS simulations, it is remarkably easy to use, yet sophisticated enough for explorations of new ideas. Other Important Features Include: * Six powerful simulations include: The Motion Generator, Rotation of Three-Dimensional Objects, Coupled Oscillators, Anharmonic Oscillators, Gravitational Orbits, and Collisions * Pascal source code for all programs is supplied and a number of exercises suggest specific ways the programs can be modified. * Simulations usually include graphical (often animated) displays. The entire CUPS simulation series consists of nine book/software simulations which comprise most of the undergraduate physics major's curriculum.
Kastner, Michael
2011-03-01
The stationary points of the potential energy function V of the classical XY chain with power-law pair interactions (i.e., interactions decaying like r{-α} with the distance) are analyzed. For a class of "spinwave-type" stationary points, the asymptotic behavior of the Hessian determinant of V is computed analytically in the limit of large system size. The computation is based on the Toeplitz property of the Hessian and makes use of a Szegö-type theorem. The results serve to illustrate a recently discovered relation between phase transitions and the properties of stationary points of classical many-body potentials. In agreement with this relation, the exact phase transition potential energy of the model can be read off from the behavior of the Hessian determinant for exponents α between zero and one. For α between one and two, the phase transition is not manifest in the behavior of the determinant, and it might be necessary to consider larger classes of stationary points.
NASA Astrophysics Data System (ADS)
Oliynyk, Todd A.
2016-12-01
We introduce a new approach to analyzing the interaction between classical and quantum systems that is based on a limiting procedure applied to multi-particle Schrödinger equations. The limit equations obtained by this procedure, which we refer to as the classical-quantum limit, govern the interaction between classical and quantum systems, and they possess many desirable properties that are inherited in the limit from the multi-particle quantum system. As an application, we use the classical-quantum limit equations to identify the source of the non-local signalling that is known to occur in the classical-quantum hybrid scheme of Hall and Reginatto. We also derive the first order correction to the classical-quantum limit equation to obtain a fully consistent first order approximation to the Schrödinger equation that should be accurate for modeling the interaction between particles of disparate mass in the regime where the particles with the larger masses are effectively classical.
NASA Astrophysics Data System (ADS)
Tavernelli, Ivano; Curchod, Basile F. E.; Rothlisberger, Ursula
2010-05-01
A mixed quantum-classical method aimed at the study of nonadiabatic dynamics in the presence of external electromagnetic fields is developed within the framework of time-dependent density functional theory. To this end, we use a trajectory-based description of the quantum nature of the nuclear degrees of freedom according to Tully’s fewest switches trajectories surface hopping, where both the nonadiabatic coupling elements between the different potential energy surfaces, and the coupling with the external field are given as functionals of the ground-state electron density or, equivalently, of the corresponding Kohn-Sham orbitals. The method is applied to the study of the photodissociation dynamics of some simple molecules in gas phase.
Haywood, Matthew James; Vijendren, Ananth; Acharya, Vikas; Mulla, Rohinton; Panesar, Miss Jaan
2017-03-06
We present a case of a Caucasian woman aged 67 years referred with a 4-day history of sore throat, dysphagia, fever and nasal blockage. Examination revealed a swollen neck and pharyngeal pseudomembrane. A throat swab was positive on culture for Corynebacterium ulcerans, with toxin expression confirmed on PCR and Elek testing. A diagnosis of classical respiratory diphtheria was made, with subsequent confirmation of the patient's domesticated dog as the source of infection. The dog had recently been attacked by a wild badger and was being treated for an ear infection. The patient made a good recovery with intravenous antimicrobial and supportive therapy; however, she subsequently developed a diphtheritic polyneuropathy in the form of a severe bulbar palsy with frank aspiration necessitating percutaneous endoscopic gastrostomy feeding. A mild sensorimotor peripheral neuropathy was also diagnosed. The patient eventually made an almost complete recovery. 2017 BMJ Publishing Group Ltd.
Hincak, Zdravka; Drmić-Hofman, Irena; Mihelić, Damir
2007-12-01
Theories about the first Indo-European migration are numerous. Significant contribution in attempt to resolve these theories is given by analysing skeletal material from two biggest prehistoric archaeological sites from N-E Croatia. Eight skeletons of Starcevo culture from sites "Nama" and "Hotel" at Vinkovci (6100-5500 BC) and seven skeletons of Vucedol culture from the site Vineyard Streim at Vucedol near Vukovar (3000-2500 BC) were analysed. Methods of classical anthropological analysis tried to distinguish the differences among members of both populations, while the methods of molecular genetics were used in defining possible genetic structure of both ancient populations. Established differences speak on the behalf of the theory of Maria Gimbutas about the first Indo-European migration with a cattle breeding population from the east around 3500 BC.
Oki, Yasuhiro; Neelapu, Sattva S.; Fanale, Michelle; Kwak, Larry W.; Fayad, Luis; Rodriguez, Maria A.; Wallace, Michael; Klinger, Mark; Carlton, Victoria; Kong, Katherine; Faham, Malek; Younes, Anas
2017-01-01
Summary We applied a highly sensitive next-generation sequencing method to identify lymphoma-specific immunoglobulin gene segments in classical Hodgkin lymphoma (CHL) at initial diagnosis or recurrence, and assessed the ability of detecting such lymphoma-specific sequences in peripheral blood (PB). Seventeen CHL cases were tested and lymphoma-specific sequences were identified in 12 of the primary tumour biopsies. In 11 of these patients whose paired PB samples were available, tumour-specific clonotypes were detected in PB in eight patients. This data demonstrates the feasibility of detecting circulating tumour-specific sequences, creating an unprecedented opportunity to optimize the future treatment and monitoring strategies for patients with CHL. PMID:25818067
NASA Astrophysics Data System (ADS)
Judson, Richard S.; Rabitz, Herschel
1987-04-01
The relationship between structure in the potential surface and classical mechanical observables is examined by means of functional sensitivity analysis. Functional sensitivities provide maps of the potential surface, highlighting those regions that play the greatest role in determining the behavior of observables. A set of differential equations for the sensitivities of the trajectory components are derived. These are then solved using a Green's function method. It is found that the sensitivities become singular at the trajectory turning points with the singularities going as η-3/2, with η being the distance from the nearest turning point. The sensitivities are zero outside of the energetically and dynamically allowed region of phase space. A second set of equations is derived from which the sensitivities of observables can be directly calculated. An adjoint Green's function technique is employed, providing an efficient method for numerically calculating these quantities. Sensitivity maps are presented for a simple collinear atom-diatom inelastic scattering problem and for two Henon-Heiles type Hamiltonians modeling intramolecular processes. It is found that the positions of the trajectory caustics in the bound state problem determine regions of the highest potential surface sensitivities. In the scattering problem (which is impulsive, so that ``sticky'' collisions did not occur), the positions of the turning points of the individual trajectory components determine the regions of high sensitivity. In both cases, these lines of singularities are superimposed on a rich background structure. Most interesting is the appearance of classical interference effects. The interference features in the sensitivity maps occur most noticeably where two or more lines of turning points cross. The important practical motivation for calculating the sensitivities derives from the fact that the potential is a function, implying that any direct attempt to understand how local
Dell'Angelo, David; Hanna, Gabriel
2016-02-09
Over the past decade, several algorithms have been developed for calculating observables using mixed quantum-classical Liouville dynamics, which differ in how accurately they solve the quantum-classical Liouville equation (QCLE). One of these algorithms, known as sequential short-time propagation (SSTP), is a surface-hopping algorithm that solves the QCLE almost exactly, but obtaining converged values of observables requires very large ensembles of trajectories due to the rapidly growing statistical errors inherent to this algorithm. To reduce the ensemble sizes, two filtering schemes (viz., observable cutting and transition filtering) have been previously developed and effectively applied to both simple and complex models. However, these schemes are either ad hoc in nature or require significant trial and error for them to work as intended. In this study, we present a self-consistent scheme, which, in combination with a soundly motivated probability function used for the Monte Carlo sampling of the nonadiabatic transitions, avoids the ad hoc observable cutting and reduces the amount of trial and error required for the transition filtering to work. This scheme is tested on the spin-boson model, in the weak, intermediate, and strong coupling regimes. Our transition filtered results obtained using a newly proposed probability function, which favors the sampling of nonadiabatic transitions with small energy gaps, show a significant improvement in accuracy and efficiency for all coupling regimes over the results obtained using observable cutting and the original implementation of transition filtering and are comparable to those obtained using the combination of these two techniques. It is therefore expected that this novel scheme will substantially reduce ensemble sizes and simplify the computation of observables in more complex systems.
Viridi, S.; Kurniadi, R.; Waris, A.; Perkasa, Y. S.
2012-06-06
Molecular dynamics in 2-D accompanied by granular model provides an opportunity to investigate binding between nuclei particles and its properties that arises during collision in a fusion reaction. A fully classical approach is used to observe the influence of initial angle of nucleus orientation to the product yielded by the reaction. As an example, a simplest fusion reaction between {sub 1}H{sup 2} and {sub 1}H{sup 3} is observed. Several products of the fusion reaction have been obtained, even the unreported ones, including temporary {sub 2}He{sup 4} nucleus.
Hlushak, Stepan P; McCabe, Clare; Cummings, Peter T
2012-09-14
We present a Fourier space density functional approach for hard particles with attractive interactions, which is based on a previously developed two-dimensional approach [S. Hlushak, W. Rżysko, and S. Sokołowski, J. Chem. Phys. 131, 094904 (2009)] for hard-sphere chains. The interactions are incorporated by means of a three-dimensional Fourier image of the direct correlation function that is obtained from the first-order mean-spherical approximation. In order to improve the computational efficiency, we make extensive use of fast Fourier transforms for calculating density convolution integrals. A two-dimensional implementation of the new density functional approach, based on the expansion of the functional around the bulk fluid density, is used to study structure and adsorption of two model fluids in narrow cylindrical pores. We also investigate two methods that improve the accuracy of the theory as compared to the conventional DFT approach, which expands the free energy functional around the bulk fluid density: One a variant of the reference fluid density functional theory used by Gillespie et al. [Phys. Rev. E 68, 031503 (2003)], and the second a weighted density approach with energy route thermodynamics. Results from these two methods are compared to the conventional approach and also to the results of Monte Carlo simulations. We find that the method of Gillespie et al. and the weighted density approach with energy route thermodynamics yield significant improvement over the conventional approach.
NASA Astrophysics Data System (ADS)
Saydanzad, Erfan; Li, Jianxiong; Thumm, Uwe
2017-05-01
Attosecond time-resolved spectroscopy has been shown to be a powerful method for examining the electronic dynamics in atoms, and this technique is now being transferred to the investigation of elastic and inelastic scattering during electron transport and collective electronic (plasmonic) effects in solids. By sampling over classical photoelectron trajectories, we simulated streaked photoelectron energy spectra as a function of the time delay between ionizing isolated attosecond extreme ultraviolet (XUV) pulses and assisting infrared or visible streaking laser pulses. Our calculations comprise a sequence of four steps: XUV excitation, electron transport in matter, escape from the surface, and propagation to the photoelectron detector. Based on numerical applications to gold nanospheres of 5- and 50-nm radius, we investigate streaked photoemission spectra with regard to (i) the nanoparticle's dielectric response to the electric field of the streaking laser pulse, (ii) relative contributions to photoelectron release from different locations on the surface and inside the nanoparticle, (iii) contributions of photoemission from the Fermi level only versus emission from the entire occupied conduction band, and (iv) their fidelity in imaging the spatiotemporal distribution of the induced plasmonic field near the particle's surface.
Li, Xin; Carravetta, Vincenzo; Li, Cui; Monti, Susanna; Rinkevicius, Zilvinas; Ågren, Hans
2016-07-12
Motivated by the growing importance of organometallic nanostructured materials and nanoparticles as microscopic devices for diagnostic and sensing applications, and by the recent considerable development in the simulation of such materials, we here choose a prototype system - para-nitroaniline (pNA) on gold nanoparticles - to demonstrate effective strategies for designing metal nanoparticles with organic conjugates from fundamental principles. We investigated the motion, adsorption mode, and physical chemistry properties of gold-pNA particles, increasing in size, through classical molecular dynamics (MD) simulations in connection with quantum chemistry (QC) calculations. We apply the quantum mechanics-capacitance molecular mechanics method [Z. Rinkevicius et al. J. Chem. Theory Comput. 2014, 10, 989] for calculations of the properties of the conjugate nanoparticles, where time dependent density functional theory is used for the QM part and a capacitance-polarizability parametrization of the MM part, where induced dipoles and charges by metallic charge transfer are considered. Dispersion and short-range repulsion forces are included as well. The scheme is applied to one- and two-photon absorption of gold-pNA clusters increasing in size toward the nanometer scale. Charge imaging of the surface introduces red-shifts both because of altered excitation energy dependence and variation of the relative intensity of the inherent states making up for the total band profile. For the smaller nanoparticles the difference in the crystal facets are important for the spectral outcome which is also influenced by the surrounding MM environment.
Sevryuk, Mikhail B.; Lombardi, Andrea; Aquilanti, Vincenzo
2005-09-15
Rigorous and complete definitions of two partitions and one expansion for the kinetic energy of a general N-particle classical system are given. Our recent work, which also provides examples of applications to the molecular dynamics of nanoaggregates, based on computer programs formulated on the basis of the theory presented here, is extended to cover arbitrary physical space dimensions. The partitions and the expansion are in terms of quantities conceived to be instantaneous phase-space invariants - a far-reaching generalization of integrals of the motion. These quantities are introduced setting out as starting points the position matrix Z of the system and the time derivative of Z. In the simplest case, the matrix Z contains the mass-scaled Cartesian coordinates of the N particles. From the position matrix, the kinematic rotations naturally arise through orthogonal transformations, as a concept 'dual' to the ordinary physical rotations. The physical meaning of each partition (expansion) term is clearly described and emphasized, and formulas for the various quantities are provided as well as inequalities among them. Proofs are presented making extensive use of the singular value decomposition (SVD) of matrices and of the signed SVD, an extended version overcoming possible singularities for particular values of N.
Getting into Classical Chinese
ERIC Educational Resources Information Center
Kent, George W.
1976-01-01
The world of classical Chinese is distant both in time and space from the world of the English-speaking American. The instructor must not, however, use a no-attention-to-meaning approach assuming some words are untranslateable or create confusion in discussing the nature of Chinese script. (CFM)
Classical Dynamics of Fullerenes
NASA Astrophysics Data System (ADS)
Sławianowski, Jan J.; Kotowski, Romuald K.
2017-06-01
The classical mechanics of large molecules and fullerenes is studied. The approach is based on the model of collective motion of these objects. The mixed Lagrangian (material) and Eulerian (space) description of motion is used. In particular, the Green and Cauchy deformation tensors are geometrically defined. The important issue is the group-theoretical approach to describing the affine deformations of the body. The Hamiltonian description of motion based on the Poisson brackets methodology is used. The Lagrange and Hamilton approaches allow us to formulate the mechanics in the canonical form. The method of discretization in analytical continuum theory and in classical dynamics of large molecules and fullerenes enable us to formulate their dynamics in terms of the polynomial expansions of configurations. Another approach is based on the theory of analytical functions and on their approximations by finite-order polynomials. We concentrate on the extremely simplified model of affine deformations or on their higher-order polynomial perturbations.
Prequantum Classical Statistical Field Theory: Fundamentals
Khrennikov, Andrei
2011-03-28
We present fundamentals of a prequantum model with hidden variables of the classical field type. In some sense this is the comeback of classical wave mechanics. Our approach also can be considered as incorporation of quantum mechanics into classical signal theory. All quantum averages (including correlations of entangled systems) can be represented as classical signal averages and correlations.
NASA Astrophysics Data System (ADS)
Zhou, T.; Popescu, S. C.; Krause, K.
2016-12-01
Waveform Light Detection and Ranging (LiDAR) data have advantages over discrete-return LiDAR data in accurately characterizing vegetation structure. However, we lack a comprehensive understanding of waveform data processing approaches under different topography and vegetation conditions. The objective of this paper is to highlight a novel deconvolution algorithm, the Gold algorithm, for processing waveform LiDAR data with optimal deconvolution parameters. Further, we present a comparative study of waveform processing methods to provide insight into selecting an approach for a given combination of vegetation and terrain characteristics. We employed two waveform processing methods: 1) direct decomposition, 2) deconvolution and decomposition. In method two, we utilized two deconvolution algorithms - the Richardson Lucy (RL) algorithm and the Gold algorithm. The comprehensive and quantitative comparisons were conducted in terms of the number of detected echoes, position accuracy, the bias of the end products (such as digital terrain model (DTM) and canopy height model (CHM)) from discrete LiDAR data, along with parameter uncertainty for these end products obtained from different methods. This study was conducted at three study sites that include diverse ecological regions, vegetation and elevation gradients. Results demonstrate that two deconvolution algorithms are sensitive to the pre-processing steps of input data. The deconvolution and decomposition method is more capable of detecting hidden echoes with a lower false echo detection rate, especially for the Gold algorithm. Compared to the reference data, all approaches generate satisfactory accuracy assessment results with small mean spatial difference (<1.22 m for DTMs, < 0.77 m for CHMs) and root mean square error (RMSE) (<1.26 m for DTMs, < 1.93 m for CHMs). More specifically, the Gold algorithm is superior to others with smaller root mean square error (RMSE) (< 1.01m), while the direct decomposition approach
Randomness: Quantum versus classical
NASA Astrophysics Data System (ADS)
Khrennikov, Andrei
2016-05-01
Recent tremendous development of quantum information theory has led to a number of quantum technological projects, e.g. quantum random generators. This development had stimulated a new wave of interest in quantum foundations. One of the most intriguing problems of quantum foundations is the elaboration of a consistent and commonly accepted interpretation of a quantum state. Closely related problem is the clarification of the notion of quantum randomness and its interrelation with classical randomness. In this short review, we shall discuss basics of classical theory of randomness (which by itself is very complex and characterized by diversity of approaches) and compare it with irreducible quantum randomness. We also discuss briefly “digital philosophy”, its role in physics (classical and quantum) and its coupling to the information interpretation of quantum mechanics (QM).
Saccà, Maria Ludovica; Fajardo, Carmen; Costa, Gonzalo; Lobo, Carmen; Nande, Mar; Martin, Margarita
2014-06-01
Nanosized zero-valent iron (nZVI) is a new option for the remediation of contaminated soil and groundwater, but the effect of nZVI on soil biota is mostly unknown. In this work, nanotoxicological studies were performed in vitro and in two different standard soils to assess the effect of nZVI on autochthonous soil organisms by integrating classical and molecular analysis. Standardised ecotoxicity testing methods using Caenorhabditis elegans were applied in vitro and in soil experiments and changes in microbial biodiversity and biomarker gene expression were used to assess the responses of the microbial community to nZVI. The classical tests conducted in soil ruled out a toxic impact of nZVI on the soil nematode C. elegans in the test soils. The molecular analysis applied to soil microorganisms, however, revealed significant changes in the expression of the proposed biomarkers of exposure. These changes were related not only to the nZVI treatment but also to the soil characteristics, highlighting the importance of considering the soil matrix on a case by case basis. Furthermore, due to the temporal shift between transcriptional responses and the development of the corresponding phenotype, the molecular approach could anticipate adverse effects on environmental biota. Copyright © 2013 Elsevier Ltd. All rights reserved.
Machado, Nelson; Oppolzer, David; Ramos, Ana; Ferreira, Luis; Rosa, Eduardo As; Rodrigues, Miguel; Domínguez-Perles, Raúl; Barros, Ana Irna
2017-10-01
Freezing represents a common conservation practice regarding vegetal foodstuffs. Since compositional features need to be monitored during storage, the development of rapid monitoring tools suitable for assessing nutritional characteristics arises as a pertinent issue. In this study, cowpea (Vigna unguiculata L.) pods, both fresh and after 6 and 9 months of freezing at -18 °C, were evaluated by high-performance liquid chromatography for their content of protein as well as of essential and nonessential amino acids, while their Fourier transform infrared spectra in the mid infrared (MIR) and near infrared (NIR) ranges were concomitantly registered to assess the feasibility of this approach for the traceability of these frozen matrices. For the NIR interval, the application of the 1st derivative to the spectral data retrieved the best results, while for lower concentrations the application of the Savitzky-Golay algorithm was indispensable to achieve quantification models for the amino acids. MIR is also suitable for this purpose, though being unable to quantify amino acids with concentrations below 0.07 mmol g(-1) dry weight, irrespective of the data treatment used. The spectroscopic approach constitutes a methodology suitable for monitoring the impact of freezing on the nutritional properties of cowpea pods, allowing accurate quantification of the protein and amino acid contents, while NIR displayed better performance. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Medcraft, Chris; Zinn, Sabrina; Schnell, Melanie; Poblotzki, Anja; Altnöder, Jonas; Heger, Matthias; Suhm, Martin A; Bernhard, Dominic; Stamm, Anke; Dietrich, Fabian; Gerhards, Markus
2016-09-21
Dispersion interactions are omnipresent in intermolecular interactions, but their respective contributions are difficult to predict. Aromatic ethers offer competing docking sites for alcohols: the ether oxygen as a well known hydrogen bond acceptor, but also the aromatic π system. The interaction with two aromatic moieties in diphenyl ether can tip the balance towards π binding. We use a multi-spectroscopic approach to study the molecular recognition, the structure and internal dynamics of the diphenyl ether-methanol complex, employing infrared, infrared-ultraviolet and microwave spectroscopy. We find that the conformer with the hydroxy group of the alcohol binding to one aromatic π cloud and being coordinated by an aromatic C-H bond of the other phenyl group is preferred. Depending on the expansion conditions in the supersonic jet, we observe a second conformer, which exhibits a hydrogen bond to the ether oxygen and is higher in energy.
Delgado, João; Pollard, Simon; Snary, Emma; Black, Edgar; Prpich, George; Longhurst, Phil
2013-08-01
Exotic animal diseases (EADs) are characterized by their capacity to spread global distances, causing impacts on animal health and welfare with significant economic consequences. We offer a critique of current import risk analysis approaches employed in the EAD field, focusing on their capacity to assess complex systems at a policy level. To address the shortcomings identified, we propose a novel method providing a systematic analysis of the likelihood of a disease incursion, developed by reference to the multibarrier system employed for the United Kingdom. We apply the network model to a policy-level risk assessment of classical swine fever (CSF), a notifiable animal disease caused by the CSF virus. In doing so, we document and discuss a sequence of analyses that describe system vulnerabilities and reveal the critical control points (CCPs) for intervention, reducing the likelihood of U.K. pig herds being exposed to the CSF virus. © 2012 Society for Risk Analysis.
Lerner, P.B.; LaGattuta, K.; Cohen, J.S.
1996-01-01
Employing the quasi-classical Fermi molecular dynamics (FMD) method, we find no evidence for the existence of a nonsequential double-ionization mechanism for helium interacting with a pulse of circularly polarized, high-intensity laser radiation. This contrasts with our earlier research, for linearly polarized laser light [Phys. Rev. A {bold 49,} R12 (1994)], in which effects of the nonsequential double ionization of helium were noted. We also compute emitted-electron kinetic energy spectra by FMD and compare these with spectra derived from a quasi-static tunneling model calculation. In this context we discuss the applicability of the FMD approach to simulations of the photoionization of multielectron systems by intense pulsed laser fields. {copyright} {ital 1996 Optical Society of America.}
NASA Astrophysics Data System (ADS)
Lerner, P. B.; Lagattuta, K.; Cohen, James S.
1996-01-01
Employing the quasi-classical Fermi molecular dynamics (FMD) method, we find no evidence for the existence of a nonsequential double-ionization mechanism for helium interacting with a pulse of circularly polarized, high-intensity laser radiation. This contrasts with our earlier research, for linearly polarized laser light [Phys.Rev.A 49, R12 (1994)], in which effects of the nonsequential double ionization of helium were noted. We also compute emitted-electron kinetic energy spectra by FMD and compare these with spectra derived from a quasi-static tunneling model calculation. In this context we discuss the applicability of the FMD approach to simulations of the photoionization of multielectron systems by intense pulsed laser fields.
NASA Astrophysics Data System (ADS)
Jagiello, Karolina; Grzonkowska, Monika; Swirog, Marta; Ahmed, Lucky; Rasulev, Bakhtiyor; Avramopoulos, Aggelos; Papadopoulos, Manthos G.; Leszczynski, Jerzy; Puzyn, Tomasz
2016-09-01
In this contribution, the advantages and limitations of two computational techniques that can be used for the investigation of nanoparticles activity and toxicity: classic nano-QSAR (Quantitative Structure-Activity Relationships employed for nanomaterials) and 3D nano-QSAR (three-dimensional Quantitative Structure-Activity Relationships, such us Comparative Molecular Field Analysis, CoMFA/Comparative Molecular Similarity Indices Analysis, CoMSIA analysis employed for nanomaterials) have been briefly summarized. Both approaches were compared according to the selected criteria, including: efficiency, type of experimental data, class of nanomaterials, time required for calculations and computational cost, difficulties in the interpretation. Taking into account the advantages and limitations of each method, we provide the recommendations for nano-QSAR modellers and QSAR model users to be able to determine a proper and efficient methodology to investigate biological activity of nanoparticles in order to describe the underlying interactions in the most reliable and useful manner.
Capuani, Caroline; Rouquette, Jacques; Payré, Bruno; Moscovici, Jacques; Delisle, Marie Bernadette; Telmon, Norbert; Guilbeau-Frugier, Céline
2013-01-01
Characterization of sharp-force trauma on human bones can be extremely useful in providing information regarding the nature and context of death. Nevertheless, in the identification of weapons used to cause sharp-force trauma and analysis of bone wounds, challenging tasks still remain. Current analysis attempting to dissect bone wound characteristics varied quite a lot and mixed different criteria, thus leading sometimes to conflicting results. In this context, the aim of our study is to clarify qualitative aspects of cut marks induced by sharp weapons on human bones. For that purpose, we analyzed bone samples via an original approach based on bone autofluorescence with an epifluorescence macroscope and compared it to previous existing methods. In this study, we used bone sections from human clavicles on which three different kinds of lesions were manually implemented, using different weapons. The bone wounds were analyzed by three different methodologies, light microscopy, scanning electron microscopy (SEM), and micro-computed tomography, and were compared with epifluorescence macroscopy. We paid attention more significantly to the aspect of walls and floor of the kerf, so as to conclude on the nature and distinguish between weapons used. Among all technologies used in this study, the most precise and efficient methods were epifluorescence macroscopy and SEM. Nonetheless, epifluorescence macroscopy is faster, cheaper, and more accessible than SEM. More significantly, this technique, which has the potential to accurately document the nature of the damage, is nondestructive, and could thus be highly useful in forensic science as anthropology.
Spallone, Aldo; Vidal, Roberto V.; Gonzales, Justo G.
2010-01-01
Objective: Pituitary adenomas invading the cavernous sinus represent a therapeutic challenge. Those tumors have been traditionally treated with incomplete surgical removal, observation and/ or adjunctive medical therapy, and radiotherapy. In relatively recent years, some authors have suggested a main direct surgical approach to cavernous sinus (CS) with the aim of complete removal of the adenoma, either by a modified trans-sphenoidal route, using or not an endoscopy-assisted approach, or by a transcranial direct approach. The latter has the advantage of allowing direct exposure of the lesion with a view of the surgical field unhindered by important neurovascular structures. Materials and Methods: We report a technical modification of the classical epidural approach for CS adenoma removal. This was used in 14 patients. Surgical technique included a fronto-orbito-zygomatic craniotomy with extradural anterior clinoidectomy, and intradural approach to the Hakuba’s triangle for intracavernous dissection. The tumors were removed under direct vision. Results: Total macroscopical removal was achieved in all but one case. This patient required postoperative radiation therapy as well as adjuvant dopaminergic regime for achieving control of preoperatively increased hormonal values. No other case required radiotherapy. Hormonal and/ or clinical control was also achieved in all the remaining cases. Out of the remaining 13 cases, all appeared to be tumor free at an average postoperative observation at 78 months (34 to 90 months). Significant surgical sequels were detected in only 1 case (persistent 3rd nerve palsy and moderate hemiparesis). Conclusions: This experience, though limited, would suggest that the transcranial limited CS exposure through the Hakuba’s triangle may allow adequate removal of intracavernous pituitary adenomas with very good long-term results and acceptable complication rate. PMID:20847907
NASA Astrophysics Data System (ADS)
Boiselet, Aurelien; Scotti, Oona; Lyon-Caen, Hélène
2014-05-01
The Corinth rift, Greece, is one of the regions with highest strain rates in the Euro-Mediterranean area and as such it has long been identified as a site of major importance for earthquake studies in Europe (20 years of research by the Corinth Rift Laboratory and 4 years of in-depth studies by the ANR-SISCOR project). This enhanced knowledge, acquired in particular, in the western part of the Gulf of Corinth, an area about 50 by 40 km, between the city of Patras to the west and the city of Aigion to the east, provides an excellent opportunity to compare fault-based and classical seismotectonic approaches currently used in seismic hazard assessment studies. A homogeneous earthquake catalogue was first constructed for the Greek territory based on two existing earthquake catalogues available for Greece (National Observatory of Athens and Thessaloniki). In spite of numerous documented damaging earthquakes, only a limited amount of macroseismic intensity data points are available in the existing databases for the damaging earthquakes affecting the west Corinth rift region. A re-interpretation of the macroseismic intensity field for numerous events was thus conducted, following an in-depth analysis of existing and newly found documentation (for details see Rovida et al. EGU2014-6346). In parallel, the construction of a comprehensive database of all relevant geological, geodetical and geophysical information (available in the literature and recently collected within the ANR-SISCOR project), allowed proposing rupture geometries for the different fault-systems identified in the study region. The combination of the new earthquake parameters and the newly defined fault geometries, together with the existing published paleoseismic data, allowed proposing a suite of rupture scenarios including the activation of multiple fault segments. The methodology used to achieve this goal consisted in setting up a logic tree that reflected the opinion of all the members of the ANR
Morgan, Simeon J; Paolini, Antonio G
2012-06-06
Acute animal preparations have been used in research prospectively investigating electrode designs and stimulation techniques for integration into neural auditory prostheses, such as auditory brainstem implants and auditory midbrain implants. While acute experiments can give initial insight to the effectiveness of the implant, testing the chronically implanted and awake animals provides the advantage of examining the psychophysical properties of the sensations induced using implanted devices. Several techniques such as reward-based operant conditioning, conditioned avoidance, or classical fear conditioning have been used to provide behavioral confirmation of detection of a relevant stimulus attribute. Selection of a technique involves balancing aspects including time efficiency (often poor in reward-based approaches), the ability to test a plurality of stimulus attributes simultaneously (limited in conditioned avoidance), and measure reliability of repeated stimuli (a potential constraint when physiological measures are employed). Here, a classical fear conditioning behavioral method is presented which may be used to simultaneously test both detection of a stimulus, and discrimination between two stimuli. Heart-rate is used as a measure of fear response, which reduces or eliminates the requirement for time-consuming video coding for freeze behaviour or other such measures (although such measures could be included to provide convergent evidence). Animals were conditioned using these techniques in three 2-hour conditioning sessions, each providing 48 stimulus trials. Subsequent 48-trial testing sessions were then used to test for detection of each stimulus in presented pairs, and test discrimination between the member stimuli of each pair. This behavioral method is presented in the context of its utilisation in auditory prosthetic research. The implantation of electrocardiogram telemetry devices is shown. Subsequent implantation of brain electrodes into the Cochlear
What classicality? Decoherence and Bohr's classical concepts
NASA Astrophysics Data System (ADS)
Schlosshauer, Maximilian; Camilleri, Kristian
2011-03-01
Niels Bohr famously insisted on the indispensability of what he termed "classical concepts." In the context of the decoherence program, on the other hand, it has become fashionable to talk about the "dynamical emergence of classicality" from the quantum formalism alone. Does this mean that decoherence challenges Bohr's dictum—for example, that classical concepts do not need to be assumed but can be derived? In this paper we'll try to shed some light down the murky waters where formalism and philosophy cohabitate. To begin, we'll clarify the notion of classicality in the decoherence description. We'll then discuss Bohr's and Heisenberg's take on the quantum—classical problem and reflect on different meanings of the terms "classicality" and "classical concepts" in the writings of Bohr and his followers. This analysis will allow us to put forward some tentative suggestions for how we may better understand the relation between decoherence-induced classicality and Bohr's classical concepts.
Petrone, Alessio; Cerezo, Javier; Ferrer, Francisco J Avila; Donati, Greta; Improta, Roberto; Rega, Nadia; Santoro, Fabrizio
2015-05-28
We study the absorption and emission electronic spectra in an aqueous solution of N-methyl-6-oxyquinolinium betaine (MQ), an interesting dye characterized by a large change of polarity and H-bond ability between the ground (S0) and the excited (S1) states. To that end we compare alternative approaches based either on explicit solvent models and density functional theory (DFT)/molecular-mechanics (MM) calculations or on DFT calculations on clusters models embedded in a polarizable continuum (PCM). In the first approach (ClMD), the spectrum is computed according to the classical Franck-Condon principle, from the dispersion of the time-dependent (TD)-DFT vertical transitions at selected snapshots of molecular dynamics (MD) on the initial state. In the cluster model (Qst) the spectrum is simulated by computing the quantum vibronic structure, estimating the inhomogeneous broadening from state-specific TD-DFT/PCM solvent reorganization energies. While both approaches provide absorption and emission spectral shapes in nice agreement with experiment, the Stokes shift is perfectly reproduced by Qst calculations if S0 and S1 clusters are selected on the grounds of the MD trajectory. Furthermore, Qst spectra better fit the experimental line shape, mostly in absorption. Comparison of the predictions of the two approaches is very instructive: the positions of Qst and ClMD spectra are shifted due to the different solvent models and the ClMD spectra are narrower than the Qst ones, because MD underestimates the width of the vibrational density of states of the high-frequency modes coupled to the electronic transition. On the other hand, both Qst and ClMD approaches highlight that the solvent has multiple and potentially opposite effects on the spectral width, so that the broadening due to solute-solvent vibrations and electrostatic interaction with bulk solvent is (partially) counterbalanced by a narrowing of the contribution due to the solute vibrational modes. Qst analysis
Si, Wei; Wu, Chang-Qin
2015-07-14
We explore an instantaneous decoherence correction (IDC) approach for the decoherence and energy relaxation in the quantum-classical dynamics of charge transport in organic semiconducting crystals. These effects, originating from environmental fluctuations, are essential ingredients of the carrier dynamics. The IDC is carried out by measurement-like operations in the adiabatic representation. While decoherence is inherent in the IDC, energy relaxation is taken into account by considering the detailed balance through the introduction of energy-dependent reweighing factors, which could be either Boltzmann (IDC-BM) or Miller-Abrahams (IDC-MA) type. For a non-diagonal electron-phonon coupling model, it is shown that IDC tends to enhance diffusion while energy relaxation weakens this enhancement. As expected, both the IDC-BM and IDC-MA achieve a near-equilibrium distribution at finite temperatures in the diffusion process, while in the Ehrenfest dynamics the electronic system tends to infinite temperature limit. The resulting energy relaxation times with the two kinds of factors lie in different regimes and exhibit different dependences on temperature, decoherence time, and electron-phonon coupling strength, due to different dominant relaxation processes.
NASA Astrophysics Data System (ADS)
Daneshmand, R. N.; Tavassoly, M. K.
2015-05-01
Following the approach of Solano et al (2003 Phys. Rev. Lett. 90 027903) we propose a scheme for a generation of a few classes of entangled (nonlinear) coherent states. To achieve this purpose, the interaction of a spatially narrow collection of two-level atoms with a quantized field in a high-Q factor cavity in the presence of a strong-driving classical field is studied. We perform appropriate Hamiltonians describing the atom-field interaction by focusing on two particular forms of intensity-dependent functions which are directly related to su(1, 1) and su(2) Lie algebras. It is shown that the dynamical evolution of the considered systems can generate bipartite, tripartite (nonlinear) and more complicated entangled states corresponding to the mentioned groups depending on the number of atoms in the cavity. In the processes of the abovementioned generation schemes, even and odd nonlinear coherent states are produced. In the end, in a particular circumstance with the two-mode quantized field we can turn easily from Jaynes-Cummings to anti-Jaynes-Cummings interactions which brings us to the maximally entangled number state. Finally, to quantify the degree of entanglement of the produced states, the measures of von Neumann and linear entropies are applied.
Si, Wei; Wu, Chang-Qin
2015-07-14
We explore an instantaneous decoherence correction (IDC) approach for the decoherence and energy relaxation in the quantum-classical dynamics of charge transport in organic semiconducting crystals. These effects, originating from environmental fluctuations, are essential ingredients of the carrier dynamics. The IDC is carried out by measurement-like operations in the adiabatic representation. While decoherence is inherent in the IDC, energy relaxation is taken into account by considering the detailed balance through the introduction of energy-dependent reweighing factors, which could be either Boltzmann (IDC-BM) or Miller-Abrahams (IDC-MA) type. For a non-diagonal electron-phonon coupling model, it is shown that IDC tends to enhance diffusion while energy relaxation weakens this enhancement. As expected, both the IDC-BM and IDC-MA achieve a near-equilibrium distribution at finite temperatures in the diffusion process, while in the Ehrenfest dynamics the electronic system tends to infinite temperature limit. The resulting energy relaxation times with the two kinds of factors lie in different regimes and exhibit different dependences on temperature, decoherence time, and electron-phonon coupling strength, due to different dominant relaxation processes.
Vollmar, Horst C; Butzlaff, Martin E; Lefering, Rolf; Rieger, Monika A
2007-06-22
Thus far important findings regarding the dementia syndrome have been implemented into patients' medical care only inadequately. A professional training accounting for both, general practitioners' (GP) needs and learning preferences as well as care-relevant aspects could be a major step towards improving medical care. In the WIDA-study, entitled "Knowledge translation on dementia in general practice" two different training concepts are developed, implemented and evaluated. Both concepts are building on an evidence-based, GP-related dementia guideline and communicate the guideline's essential insights. Both development and implementation emphasize a procedure that is well-accepted in practice and, thus, can achieve a high degree of external validity. This is particularly guaranteed through the preparation of training material and the fact that general practitioners' quality circles (QC) are addressed. The evaluation of the two training concepts is carried out by comparing two groups of GPs to which several quality circles have been randomly assigned. The primary outcome is the GPs' knowledge gain. Secondary outcomes are designed to indicate the training's potential effects on the GPs' practical actions. In the first training concept (study arm A) GPs participate in a structured case discussion prepared for by internet-based learning material ("blended-learning" approach). The second training concept (study arm B) relies on frontal medical training in the form of a slide presentation and follow-up discussion ("classical" approach). This paper presents the outline of a cluster-randomized trial which has been peer reviewed and support by a national funding organization--Federal Ministry of Education and Research (BMBF)--and is approved by an ethics commission. The data collection has started in August 2006 and the results will be published independently of the study's outcome. Current Controlled Trials [ISRCTN36550981].
Vollmar, Horst C; Butzlaff, Martin E; Lefering, Rolf; Rieger, Monika A
2007-01-01
Background Thus far important findings regarding the dementia syndrome have been implemented into patients' medical care only inadequately. A professional training accounting for both, general practitioners' (GP) needs and learning preferences as well as care-relevant aspects could be a major step towards improving medical care. In the WIDA-study, entitled "Knowledge translation on dementia in general practice" two different training concepts are developed, implemented and evaluated. Both concepts are building on an evidence-based, GP-related dementia guideline and communicate the guideline's essential insights. Methods/Design Both development and implementation emphasize a procedure that is well-accepted in practice and, thus, can achieve a high degree of external validity. This is particularly guaranteed through the preparation of training material and the fact that general practitioners' quality circles (QC) are addressed. The evaluation of the two training concepts is carried out by comparing two groups of GPs to which several quality circles have been randomly assigned. The primary outcome is the GPs' knowledge gain. Secondary outcomes are designed to indicate the training's potential effects on the GPs' practical actions. In the first training concept (study arm A) GPs participate in a structured case discussion prepared for by internet-based learning material ("blended-learning" approach). The second training concept (study arm B) relies on frontal medical training in the form of a slide presentation and follow-up discussion ("classical" approach). Discussion This paper presents the outline of a cluster-randomized trial which has been peer reviewed and support by a national funding organization – Federal Ministry of Education and Research (BMBF) – and is approved by an ethics commission. The data collection has started in August 2006 and the results will be published independently of the study's outcome. Trial Registration Current Controlled Trials
Reexamining the Quantum-Classical Relation
NASA Astrophysics Data System (ADS)
Bokulich, Alisa
2008-10-01
1. Intertheoretic relations: are imperialism and isolationism our only options?; 2. Heisenberg's closed theories and pluralistic realism; 3. Dirac's open theories and the reciprocal correspondence principle; 4. Bohr's generalization of classical mechanics; 5. Semiclassical mechanics: putting quantum flesh on classical bones; 6. Can classical structures explain quantum phenomena?; 7. A structural approach to intertheoretic relations; References; Index.
Shakib, Farnaz A.; Hanna, Gabriel
2016-01-14
In a previous study [F. A. Shakib and G. Hanna, J. Chem. Phys. 141, 044122 (2014)], we investigated a model proton-coupled electron transfer (PCET) reaction via the mixed quantum-classical Liouville (MQCL) approach and found that the trajectories spend the majority of their time on the mean of two coherently coupled adiabatic potential energy surfaces. This suggested a need for mean surface evolution to accurately simulate observables related to ultrafast PCET processes. In this study, we simulate the time-dependent populations of the three lowest adiabatic states in the ET-PT (i.e., electron transfer preceding proton transfer) version of the same PCET model via the MQCL approach and compare them to the exact quantum results and those obtained via the fewest switches surface hopping (FSSH) approach. We find that the MQCL population profiles are in good agreement with the exact quantum results and show a significant improvement over the FSSH results. All of the mean surfaces are shown to play a direct role in the dynamics of the state populations. Interestingly, our results indicate that the population transfer to the second-excited state can be mediated by dynamics on the mean of the ground and second-excited state surfaces, as part of a sequence of nonadiabatic transitions that bypasses the first-excited state surface altogether. This is made possible through nonadiabatic transitions between different mean surfaces, which is the manifestation of coherence transfer in MQCL dynamics. We also investigate the effect of the strength of the coupling between the proton/electron and the solvent coordinate on the state population dynamics. Drastic changes in the population dynamics are observed, which can be understood in terms of the changes in the potential energy surfaces and the nonadiabatic couplings. Finally, we investigate the state population dynamics in the PT-ET (i.e., proton transfer preceding electron transfer) and concerted versions of the model. The PT
Shakib, Farnaz A; Hanna, Gabriel
2016-01-14
In a previous study [F. A. Shakib and G. Hanna, J. Chem. Phys. 141, 044122 (2014)], we investigated a model proton-coupled electron transfer (PCET) reaction via the mixed quantum-classical Liouville (MQCL) approach and found that the trajectories spend the majority of their time on the mean of two coherently coupled adiabatic potential energy surfaces. This suggested a need for mean surface evolution to accurately simulate observables related to ultrafast PCET processes. In this study, we simulate the time-dependent populations of the three lowest adiabatic states in the ET-PT (i.e., electron transfer preceding proton transfer) version of the same PCET model via the MQCL approach and compare them to the exact quantum results and those obtained via the fewest switches surface hopping (FSSH) approach. We find that the MQCL population profiles are in good agreement with the exact quantum results and show a significant improvement over the FSSH results. All of the mean surfaces are shown to play a direct role in the dynamics of the state populations. Interestingly, our results indicate that the population transfer to the second-excited state can be mediated by dynamics on the mean of the ground and second-excited state surfaces, as part of a sequence of nonadiabatic transitions that bypasses the first-excited state surface altogether. This is made possible through nonadiabatic transitions between different mean surfaces, which is the manifestation of coherence transfer in MQCL dynamics. We also investigate the effect of the strength of the coupling between the proton/electron and the solvent coordinate on the state population dynamics. Drastic changes in the population dynamics are observed, which can be understood in terms of the changes in the potential energy surfaces and the nonadiabatic couplings. Finally, we investigate the state population dynamics in the PT-ET (i.e., proton transfer preceding electron transfer) and concerted versions of the model. The PT
Semi-classical Electrodynamics
NASA Astrophysics Data System (ADS)
Lestone, John
2016-03-01
Quantum electrodynamics is complex and its associated mathematics can appear overwhelming for those not trained in this field. We describe semi-classical approaches that can be used to obtain a more intuitive physical feel for several QED processes including electro-statics, Compton scattering, pair annihilation, the anomalous magnetic moment, and the Lamb shift, that could be taught easily to undergraduate students. Any physicist who brings their laptop to the talk will be able to build spread sheets in less than 10 minutes to calculate g/2 =1.001160 and a Lamb shift of 1057 MHz.
Herrera-Ibatá, Diana María; Martínez-López, Beatriz; Quijada, Darla; Burton, Kenneth
2017-01-01
The US livestock safety strongly depends on its capacity to prevent the introduction of Transboundary Animal Diseases (TADs). Therefore, accurate and updated information on the location and origin of those potential TADs risks is essential, so preventive measures as market restrictions can be put on place. The objective of the present study was to evaluate the current risk of African swine fever (ASF) and Classical swine fever (CSF) introduction into the US through the legal importations of live pigs and swine products using a quantitative approach that could be later applied to other risks. Four quantitative stochastic risk assessment models were developed to estimate the monthly probabilities of ASF and CSF release into the US, and the exposure of susceptible populations (domestic and feral swine) to these introductions at state level. The results suggest a low annual probability of either ASF or CSF introduction into the US, by any of the analyzed pathways (5.5*10−3). Being the probability of introduction through legal imports of live pigs (1.8*10−3 for ASF, and 2.5*10−3 for CSF) higher than the risk of legally imported swine products (8.90*10−4 for ASF, and 1.56*10−3 for CSF). This could be caused due to the low probability of exposure associated with this type of commodity (products). The risk of feral pigs accessing to swine products discarded in landfills was slightly higher than the potential exposure of domestic pigs through swill feeding. The identification of the months at highest risk, the origin of the higher risk imports, and the location of the US states most vulnerable to those introductions (Iowa, Minnesota and Wisconsin for live swine and California, Florida and Texas for swine products), is valuable information that would help to design prevention, risk-mitigation and early-detection strategies that would help to minimize the catastrophic consequences of potential ASF/CSF introductions into the US. PMID:28797058
Herrera-Ibatá, Diana María; Martínez-López, Beatriz; Quijada, Darla; Burton, Kenneth; Mur, Lina
2017-01-01
The US livestock safety strongly depends on its capacity to prevent the introduction of Transboundary Animal Diseases (TADs). Therefore, accurate and updated information on the location and origin of those potential TADs risks is essential, so preventive measures as market restrictions can be put on place. The objective of the present study was to evaluate the current risk of African swine fever (ASF) and Classical swine fever (CSF) introduction into the US through the legal importations of live pigs and swine products using a quantitative approach that could be later applied to other risks. Four quantitative stochastic risk assessment models were developed to estimate the monthly probabilities of ASF and CSF release into the US, and the exposure of susceptible populations (domestic and feral swine) to these introductions at state level. The results suggest a low annual probability of either ASF or CSF introduction into the US, by any of the analyzed pathways (5.5*10-3). Being the probability of introduction through legal imports of live pigs (1.8*10-3 for ASF, and 2.5*10-3 for CSF) higher than the risk of legally imported swine products (8.90*10-4 for ASF, and 1.56*10-3 for CSF). This could be caused due to the low probability of exposure associated with this type of commodity (products). The risk of feral pigs accessing to swine products discarded in landfills was slightly higher than the potential exposure of domestic pigs through swill feeding. The identification of the months at highest risk, the origin of the higher risk imports, and the location of the US states most vulnerable to those introductions (Iowa, Minnesota and Wisconsin for live swine and California, Florida and Texas for swine products), is valuable information that would help to design prevention, risk-mitigation and early-detection strategies that would help to minimize the catastrophic consequences of potential ASF/CSF introductions into the US.
Primitive Ontology and the Classical World
NASA Astrophysics Data System (ADS)
Allori, Valia
In this chapter, I present the common structure of quantum theories with a primitive ontology (PO), and discuss in what sense the classical world emerges from quantum theories as understood in this framework. In addition, I argue that the PO approach is better at analyzing the classical limit than the rival wave function ontology approach or any other approach in which the classical world is non-reductively "emergent:" even if the classical limit within this framework needs to be fully developed, the difficulties are technical rather than conceptual, while this is not true for the alternatives.
Omanović, Dario; Pižeta, Ivanka; Vukosav, Petra; Kovács, Elza; Frančišković-Bilinski, Stanislav; Tamás, János
2015-04-01
The distribution and speciation of elements along a stream subjected to neutralised acid mine drainage (NAMD) effluent waters (Mátra Mountain, Hungary; Toka stream) were studied by a multi-methodological approach: dissolved and particulate fractions of elements were determined by HR-ICPMS, whereas speciation was carried out by DGT, supported by speciation modelling performed by Visual MINTEQ. Before the NAMD discharge, the Toka is considered as a pristine stream, with averages of dissolved concentrations of elements lower than world averages. A considerable increase of element concentrations caused by effluent water inflow is followed by a sharp or gradual concentration decrease. A large difference between total and dissolved concentrations was found for Fe, Al, Pb, Cu, Zn and As in effluent water and at the first downstream site, with high correlation factors between elements in particulate fraction, indicating their common behaviour, governed by the formation of ferri(hydr)oxides (co)precipitates. In-situ speciation by the DGT technique revealed that Zn, Cd, Ni, Co, Mn and U were predominantly present as a labile, potentially bioavailable fraction (>90%). The formation of strong complexes with dissolved organic matter (DOM) resulted in a relatively low DGT-labile concentration of Cu (42%), while low DGT-labile concentrations of Fe (5%) and Pb (12%) were presumably caused by their existence in colloidal (particulate) fraction which is not accessible to DGT. Except for Fe and Pb, a very good agreement between DGT-labile concentrations and those predicted by the applied speciation model was obtained, with an average correlation factor of 0.96. This study showed that the in-situ DGT technique in combination with model-predicted speciation and classical analysis of samples could provide a reasonable set of data for the assessment of the water quality status (WQS), as well as for the more general study of overall behaviour of the elements in natural waters subjected
Classical photometry of prefractal surfaces.
Shkuratov, Yuriy; Petrov, Dmitriy; Videen, Gorden
2003-11-01
Using the scale invariance of classical photometry, we develop an approach to finding the photometric function of prefractal structures that form a random topography. The photometric function of the prefractal surfaces is found as the general solution of the resulting differential equation in partial derivatives. The function depends on two parameters: the number of hierarchical levels of the prefractal structures and the roughness parameter of the single-level generation. As a limiting case, the approach includes our previous theory that considered fractoids.
Quantum computing classical physics.
Meyer, David A
2002-03-15
In the past decade, quantum algorithms have been found which outperform the best classical solutions known for certain classical problems as well as the best classical methods known for simulation of certain quantum systems. This suggests that they may also speed up the simulation of some classical systems. I describe one class of discrete quantum algorithms which do so--quantum lattice-gas automata--and show how to implement them efficiently on standard quantum computers.
ERIC Educational Resources Information Center
Boyer, Timothy H.
1985-01-01
The classical vacuum of physics is not empty, but contains a distinctive pattern of electromagnetic fields. Discovery of the vacuum, thermal spectrum, classical electron theory, zero-point spectrum, and effects of acceleration are discussed. Connection between thermal radiation and the classical vacuum reveals unexpected unity in the laws of…
ERIC Educational Resources Information Center
Boyer, Timothy H.
1985-01-01
The classical vacuum of physics is not empty, but contains a distinctive pattern of electromagnetic fields. Discovery of the vacuum, thermal spectrum, classical electron theory, zero-point spectrum, and effects of acceleration are discussed. Connection between thermal radiation and the classical vacuum reveals unexpected unity in the laws of…
ERIC Educational Resources Information Center
Seney, Bob
2008-01-01
The author is an enthusiastic supporter of using young adult literature in the classroom with gifted learners--so much, that he has been accused of being "against" the classics. Not so, but he does ask about and challenges teachers to tell him if their classroom use of the classics is appropriate. Do the classics provide the kind of interaction…
ERIC Educational Resources Information Center
Matthews, Dorothy, Ed.
1979-01-01
The eight articles in this bulletin suggest methods of introducing classical literature into the English curriculum. Article titles are: "Ideas for Teaching Classical Mythology"; "What Novels Should High School Students Read?"; "Enlivening the Classics for Live Students"; "Poetry in Performance: The Value of Song and Oral Interpretation in…
ERIC Educational Resources Information Center
Matthews, Dorothy, Ed.
1979-01-01
The eight articles in this bulletin suggest methods of introducing classical literature into the English curriculum. Article titles are: "Ideas for Teaching Classical Mythology"; "What Novels Should High School Students Read?"; "Enlivening the Classics for Live Students"; "Poetry in Performance: The Value of Song and Oral Interpretation in…
Maranhão, Bernardo Henrique Ferraz; Silva Junior, Cyro Teixeira da; Chibante, Antonio Monteiro da Silva; Cardoso, Gilberto Perez
2010-01-01
To propose a new classification criterion for the differentiation between pleural exudates and transudates-quantifying total proteins in pleural fluid (TP-PF) and lactate dehydrogenase in pleural fluid (LDH-PF) exclusively-as well as to compare this new criterion with the classical criterion in terms of diagnostic yield. This was an observational, cross-sectional study with a within-subject design, comprising 181 patients with pleural effusion treated at two university hospitals in the state of Rio de Janeiro, Brazil, between 2003 and 2006. The diagnostic parameters included in the classical criterion were identified, as were those included in the new criterion. Of the 181 patients, 152 and 29 were diagnosed with pleural exudates and pleural transudates, respectively. For the classical criterion, the sensitivity, specificity, and accuracy for the diagnosis of pleural exudates were, respectively, 99.8%, 68.6%, and 94.5%, whereas the corresponding values for the diagnosis of pleural transudates were 76.1%, 90.1%, and 87.6%. For the new criterion (cut-off points set at 3.4 g/dL for TP-PF and 328.0 U/L for LDH-PF), the sensitivity, specificity, and accuracy for the diagnosis of exudates were, respectively, 99.4%, 72.6%, and 99.2%, whereas the corresponding values for the diagnosis of transudates were 98.5%, 83.4%, and 90.0%. The accuracy of the new criterion for the diagnosis of pleural exudates was significantly greater than was that of the classical criterion (p = 0.0022). The diagnostic yield was comparable between the two criteria studied. Therefore, the new classification criterion can be used in daily practice.
NASA Astrophysics Data System (ADS)
Azadegan, B.; Wagner, W.
2015-01-01
We present a Mathematica package for simulation of spectral-angular distributions and energy spectra of planar channeling radiation of relativistic electrons and positrons channeled along major crystallographic planes of a diamond-structure or tungsten single crystal. The program is based on the classical theory of channeling radiation which has been successfully applied to study planar channeling of light charged particles at energies higher than 100 MeV. Continuous potentials for different planes of diamond, Si, Ge and W single crystals are calculated using the Doyle-Turner approximation to the atomic scattering factor and taking thermal vibrations of the crystal atoms into account. Numerical methods are applied to solve the classical one-dimensional equation of motion. The code is designed to calculate the trajectories, velocities and accelerations of electrons (positrons) channeled by the planar continuous potential. In the framework of classical electrodynamics, these data allow realistic simulations of spectral-angular distributions and energy spectra of planar channeling radiation. Since the generated output is quantitative, the results of calculation may be useful, e.g., for setup configuration and crystal alignment in channeling experiments, for the study of the dependence of channeling radiation on the input parameters of particle beams with respect to the crystal orientation, but also for the simulation of positron production by means of pair creation what is mandatory for the design of efficient positron sources necessary in high-energy and collider physics. Although the classical theory of channeling is well established for long time, there is no adequate library program for simulation of channeling radiation up to now, which is commonly available, sufficiently simple and effective to employ and, therefore, of benefit as for special investigations as for a quick overview of basic features of this type of radiation.
NASA Astrophysics Data System (ADS)
Miller, William H.; Cotton, Stephen J.
2016-08-01
It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory—e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer values of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states—and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.
Miller, William H.; Cotton, Stephen J.
2016-08-28
It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory - e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer values of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states - and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.
Miller, William H.; Cotton, Stephen J.
2016-08-28
It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory - e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer valuesmore » of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states - and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.« less
Hermeneutic reading of classic texts.
Koskinen, Camilla A-L; Lindström, Unni Å
2013-09-01
The purpose of this article is to broaden the understandinfg of the hermeneutic reading of classic texts. The aim is to show how the choice of a specific scientific tradition in conjunction with a methodological approach creates the foundation that clarifies the actual realization of the reading. This hermeneutic reading of classic texts is inspired by Gadamer's notion that it is the researcher's own research tradition and a clearly formulated theoretical fundamental order that shape the researcher's attitude towards texts and create the starting point that guides all reading, uncovering and interpretation. The researcher's ethical position originates in a will to openness towards what is different in the text and which constantly sets the researcher's preunderstanding and research tradition in movement. It is the researcher's attitude towards the text that allows the text to address, touch and arouse wonder. Through a flexible, lingering and repeated reading of classic texts, what is different emerges with a timeless value. The reading of classic texts is an act that may rediscover and create understanding for essential dimensions and of human beings' reality on a deeper level. The hermeneutic reading of classic texts thus brings to light constantly new possibilities of uncovering for a new envisioning and interpretation for a new understanding of the essential concepts and phenomena within caring science.
New Classical and New Keynesian Macroeconomics.
ERIC Educational Resources Information Center
Vane, Howard; Snowdon, Brian
1992-01-01
Summarizes underlying tenets and policy implications of new classical and new Keynesian macroeconomics. Compares new approaches with orthodox Keynesian and monetarist schools of thought. Identifies the fundamental difference between new classical and new Keynesian models as the assumption regarding the speed of wage and price adjustment following…
Teaching the Classics in High School.
ERIC Educational Resources Information Center
Shelley, Anne Crout
1998-01-01
Discusses why the classics can be difficult to teach in high schools. Offers suggestions for making difficult literature more approachable for high school students by scaffolding students' engagement with classic texts; building background knowledge; developing vocabulary; facilitating the reading of the text; and through enrichment an extension.…
Teaching the Classics in High School.
ERIC Educational Resources Information Center
Shelley, Anne Crout
1998-01-01
Discusses why the classics can be difficult to teach in high schools. Offers suggestions for making difficult literature more approachable for high school students by scaffolding students' engagement with classic texts; building background knowledge; developing vocabulary; facilitating the reading of the text; and through enrichment an extension.…
NASA Astrophysics Data System (ADS)
Hull, Tony; Westerhoff, Thomas; Pepi, John W.; Jedamzik, Ralf; Gardopee, George J.; Piché, François; Clarkson, Andrew R.; Leys, Antoine; Schaefer, Martin; Seibert, Volker
2012-09-01
Previously we established that the combination of new machining parameters for openbacked monolithic lightweighted ZERODUR® mirror substrates, coupled with new methods for optical finishing of aggressively lightweighted mirrors, have relieved classical mirror design constraints imposed upon 1.2m diameter lightweight mirrors. We demonstrate that openback mirror substrates now offer comparable mass, Eigenfrequency and substructure print-through performance to the sandwich-mirror architecture, but with considerably less manufacturing effort than for sandwich mirrors. Here we extend the analyses of the first paper from 1.2m diameter down to 0.6m in diameter and up to 2.4m diameter and 4m diameter mirrors.
Schimpchen, Jan; Skorski, Sabrina; Nopp, Stephan; Meyer, Tim
2016-01-01
The aim of this study was to investigate the occurrence of repeated sprinting bouts in elite football. Furthermore, the construct validity of current tests assessing repeated-sprint ability (RSA) was analysed using information of sprinting sequences as they actually occurred during match-play. Sprinting behaviour in official competition was analysed for 19 games of the German national team between August 2012 and June 2014. A sprinting threshold was individually calculated based on the peak velocity reached during in-game sprinting. Players performed 17.2 ± 3.9 sprints per game and during the entire 19 games a total of 35 bouts of repeated sprinting (a minimum of three consecutive sprints with a recovery duration <30 s separating efforts). This averages one bout of repeated sprinting per player every 463 min. No general decrement in maximal sprinting speed was observed during bouts with up to five consecutive sprints. Results of the present study question the importance of RSA as it is classically defined. They indicate that shorter accelerations are more important in game-specific situations which do not reach speeds necessary to qualify them as sprints. The construct validity of classic tests of RSA in football is not supported by these observations.
NASA Astrophysics Data System (ADS)
Leblond, J. B.; Mottet, G.; Devaux, J. C.
THE RESPONSE of phase-transforming steels to variations of the applied stress (i.e. the ∑-term of the classical plastic strain rate Ė cp defined in Part I) is studied both theoretically and numerically for ideal-plastic individual phases. It is found theoretically that though the stress-strain curve contains no elastic portion, it is nevertheless initially tangent to the elastic line with slope equal to Young's modulus. Moreover an explicit formula for the beginning of the curve is derived for medium or high proportions of the harder phase, and a simple upper bound is given for the ultimate stress (maximum Von Mises stress). The finite element simulation confirms and completes these results, especially concerning the ultimate stress whose discrepancy with the theoretical upper bound is found to be maximum for low proportions of the harder phase. Based on these results, a complete model is proposed for the ∑-term of the classical plastic strain rate Ė cp in the case of ideal-plastic phases.
Ryan-Ibarra, Suzanne; Milet, Meredith; Lutzker, Liza; Rodriguez, Danielle; Induni, Marta; Kreutzer, Rick
2016-02-01
Using 27 years of survey data, the contributions of age, period, and cohort effects on the increase in adult lifetime asthma prevalence in California were examined. Lifetime asthma diagnosis for adults was assessed in 1984-1992 and 1995-2011 through the California Behavioral Risk Factor Surveillance System, an annual, cross-sectional, population-based survey (n = 144,100). Using date of survey and date of birth, we classified 18,305 adult respondents with lifetime asthma into 7 age groups, 6 periods, and 17 cohorts. Using hierarchical, cross-classified random effects models, birth cohort, period, and age patterns in adult lifetime asthma prevalence were analyzed. After adjusting for sex, ethnicity, education, and smoking, age effects peak in young adulthood, flatten from 40 to 60 years old, and then decrease in older adulthood. A significant positive trend in asthma prevalence was observed in the two earliest survey periods (1984-1993; P value < .0001). Survey period trends appear to flatten beginning in 2004. Although the overall birth cohort effect was statistically significant, the magnitude of the effect for each birth cohort category was small (P value = .0005). We observed that strong age and period effects have been driving the increase in lifetime asthma prevalence in California over the past 3 decades. Copyright © 2016 Elsevier Inc. All rights reserved.
Absolutely classical spin states
NASA Astrophysics Data System (ADS)
Bohnet-Waldraff, F.; Giraud, O.; Braun, D.
2017-01-01
We introduce the concept of "absolutely classical" spin states, in analogy to absolutely separable states of bipartite quantum systems. Absolutely classical states are states that remain classical (i.e., a convex sum of projectors on coherent states of a spin j ) under any unitary transformation applied to them. We investigate the maximal size of the ball of absolutely classical states centered on the maximally mixed state and derive a lower bound for its radius as a function of the total spin quantum number. We also obtain a numerical estimate of this maximal radius and compare it to the case of absolutely separable states.
NASA Astrophysics Data System (ADS)
Gheorghiu, Vlad; de Oliveira, Marcos C.; Sanders, Barry C.
2015-07-01
Quantum discord is the quantitative difference between two alternative expressions for bipartite mutual information, given respectively in terms of two distinct definitions for the conditional entropy. By constructing a stochastic model of shared states, classical discord can be similarly defined, quantifying the presence of some stochasticity in the measurement process. Therefore, discord can generally be understood as a quantification of the system's state disturbance due to local measurements, be it quantum or classical. We establish an operational meaning of classical discord in the context of state merging with noisy measurement and thereby show the quantum-classical separation in terms of a negative conditional entropy.
Nieddu, M; Pichiri, G; Diaz, G; Mezzanotte, R
2003-01-01
Human classical satellite DNAs were used as probes to investigate the molecular mechanism(s) of AluI/TaqI attack in situ on specific centromeric areas. The biochemical results obtained show that the majority of such highly repetitive DNAs are not solubilized from chromosomes, in spite of a cleavage pattern identical to that shown in naked genomic DNA digested with the same enzymes. Moreover, when digestion in situ with restriction enzymes precedes in situ hybridization, it is possible to observe an increased signal in the centromeres of some chromosomes as compared to that shown in standard undigested chromosomes and, on the other hand, hybridization labelling in centromeres which are difficult to detect by in situ hybridization using standard undigested chromosomes. Lastly, our results show that centromeric heterochromatin is not a homogeneous class in regard to organizational structure.
NASA Astrophysics Data System (ADS)
Abd El-Wahab, N. H.; Abdel Rady, A. S.; Osman, Abdel-Nasser A.; Salah, Ahmed
2015-10-01
In this paper, a model is introduced to investigate the interaction between a three-level atom and one-mode of the radiation field. The atomic motion and the classical homogenous gravitational field are taken into consideration. For this purpose, we first introduce a set of new atomic operators obeying an su(3) algebraic structure to derive an effective Hamiltonian for the system under consideration. By solving the Schrödinger equation in the interaction picture, the exact solution is given when the atom and the field are initially prepared in excited state and coherent state, respectively. The influences of the gravity parameter on the collapses-revivals phenomena, the atomic momentum diffusion, the Mandel Q-parameter, the normal squeezing phenomena and the coherent properties for the considered system are examined. It is found that the gravity parameter has important effects on the properties of these phenomena.
Branislav, Rajić; Milivoj, Dopsaj; Abella, Carlos Pablos; Deval, Vicente Caratalla; Siniša, Karišik
2013-01-01
Background: The aim of this study is to verify the effects of the combined and classic training of different isometric rates of force development (RFD) parameters of legs. Materials and Methods: Three groups of female athletes was tested: Experimental group (N = 12), classically trained group (N = 11), and control group (N = 20) of athletes. The isometric “standing leg extension” and “Rise on Toes” tests were conducted to evaluate the maximal force, time necessary time to reach it and the RFD analyzed at 100 ms, 180 ms, 250 ms from the onset, and 50-100% of its maximal result. Results: The maximal RFD of legs and calves are dominant explosive parameters. Special training enhanced the RFD of calves of GROUPSPEC at 100 ms (P = 0.05), at 180 ms (P = 0.039), at 250 ms (P = 0.039), at 50% of the Fmax (P = 0.031) and the Fmax (P = 0.05). Domination of GROUPSPEC toward GROUPCLASS and GROUPCONTROL is in case of legs at 100 ms (P = 0.04); at 180 ms (P = 0.04); at 250 ms (P = 0.00); at 50% of the Fmax (P = 0.01) and at the Fmax (P = 0.00); in case of calves at 100 ms (P = 0.07); 180 ms (P = 0.001); at 250 ms (P = 0.00); at 50% of the Fmax (P = 0.00) and at Fmax (P = 0.000). Conclusion: Dominant explosive factors are maximal RFD of leg extensors and calves, and legs at 250ms. Specific training enhanced explosiveness of calves of GROUPSPEC general and partial domination of GROUPSPEC by 87% over GROUPCLASS, and 35% over GROUPCONTROL. PMID:24497853
NASA Technical Reports Server (NTRS)
Valley, Lois
1989-01-01
The SPS product, Classic-Ada, is a software tool that supports object-oriented Ada programming with powerful inheritance and dynamic binding. Object Oriented Design (OOD) is an easy, natural development paradigm, but it is not supported by Ada. Following the DOD Ada mandate, SPS developed Classic-Ada to provide a tool which supports OOD and implements code in Ada. It consists of a design language, a code generator and a toolset. As a design language, Classic-Ada supports the object-oriented principles of information hiding, data abstraction, dynamic binding, and inheritance. It also supports natural reuse and incremental development through inheritance, code factoring, and Ada, Classic-Ada, dynamic binding and static binding in the same program. Only nine new constructs were added to Ada to provide object-oriented design capabilities. The Classic-Ada code generator translates user application code into fully compliant, ready-to-run, standard Ada. The Classic-Ada toolset is fully supported by SPS and consists of an object generator, a builder, a dictionary manager, and a reporter. Demonstrations of Classic-Ada and the Classic-Ada Browser were given at the workshop.
ERIC Educational Resources Information Center
Hansen, James
1978-01-01
Sponsored by a consortium of 30 American universities, Rome's Intercollegiate Center for Classical Studies offers a year of study to American undergraduate classics majors. Instructors are also American and normally stay only a year; teaching assistants are always ex-students of the center. Extensive field trips are an important part of the…
ERIC Educational Resources Information Center
Kilburn, K.
1975-01-01
Criticizes traditional reasons for Classics study and states that education is the initiation of a new generation into the skills and knowledge structures of an existing tradition. Aesthetics and philosophy, religion and morals, knowledge of self and others, and mathematics and science may be understood through Classics.
Classical/Non‐classical Polyoxometalate Hybrids
Santiago‐Schübel, Beatrix; Willbold, Sabine; Heß, Volkmar
2016-01-01
Abstract Two polyanions [SeI V 2PdII 4WVI 14O56H]11− and [SeI V 4PdII 4WVI 28O108H12]12− are the first hybrid polyoxometalates in which classical (Group 5/6 metal based) and non‐classical (late transition‐metal based) polyoxometalate units are joined. Requiring no supporting groups, this co‐condensation of polyoxotungstate and isopolyoxopalladate constituents also provides a logical link between POM‐PdII coordination complexes and the young subclass of polyoxopalladates. Solid‐state, solution, and gas‐phase studies suggest interesting specific reactivities for these hybrids and point to several potential derivatives and functionalization strategies. PMID:27617918
Diagrammar in classical scalar field theory
Cattaruzza, E.; Gozzi, E.; Francisco Neto, A.
2011-09-15
In this paper we analyze perturbatively a g{phi}{sup 4}classical field theory with and without temperature. In order to do that, we make use of a path-integral approach developed some time ago for classical theories. It turns out that the diagrams appearing at the classical level are many more than at the quantum level due to the presence of extra auxiliary fields in the classical formalism. We shall show that a universal supersymmetry present in the classical path-integral mentioned above is responsible for the cancelation of various diagrams. The same supersymmetry allows the introduction of super-fields and super-diagrams which considerably simplify the calculations and make the classical perturbative calculations almost 'identical' formally to the quantum ones. Using the super-diagrams technique, we develop the classical perturbation theory up to third order. We conclude the paper with a perturbative check of the fluctuation-dissipation theorem. - Highlights: > We provide the Feynman diagrams of perturbation theory for a classical field theory. > We give a super-formalism which links the quantum diagrams to the classical ones. > We check perturbatively the fluctuation-dissipation theorem.
NASA Astrophysics Data System (ADS)
Hegazy, Maha Abdel Monem; Fayez, Yasmin Mohammed
2015-04-01
Two different methods manipulating spectrophotometric data have been developed, validated and compared. One is capable of removing the signal of any interfering components at the selected wavelength of the component of interest (univariate). The other includes more variables and extracts maximum information to determine the component of interest in the presence of other components (multivariate). The applied methods are smart, simple, accurate, sensitive, precise and capable of determination of spectrally overlapped antihypertensives; hydrochlorothiazide (HCT), irbesartan (IRB) and candesartan (CAN). Mean centering of ratio spectra (MCR) and concentration residual augmented classical least-squares method (CRACLS) were developed and their efficiency was compared. CRACLS is a simple method that is capable of extracting the pure spectral profiles of each component in a mixture. Correlation was calculated between the estimated and pure spectra and was found to be 0.9998, 0.9987 and 0.9992 for HCT, IRB and CAN, respectively. The methods were successfully determined the three components in bulk powder, laboratory-prepared mixtures, and combined dosage forms. The results obtained were compared statistically with each other and to those of the official methods.
NASA Astrophysics Data System (ADS)
Yu, Nengkun; Guo, Cheng; Duan, Runyao
2014-04-01
We introduce a notion of the entanglement transformation rate to characterize the asymptotic comparability of two multipartite pure entangled states under stochastic local operations and classical communication (SLOCC). For two well known SLOCC inequivalent three-qubit states |GHZ⟩=(1/√2 )(|000⟩+|111⟩) and |W⟩=(1/√3 )(|100⟩+|010⟩+|001⟩), we show that the entanglement transformation rate from |GHZ⟩ to |W⟩ is exactly 1. That means that we can obtain one copy of the W state from one copy of the Greenberg-Horne-Zeilinger (GHZ) state by SLOCC, asymptotically. We then apply similar techniques to obtain a lower bound on the entanglement transformation rates from an N-partite GHZ state to a class of Dicke states, and prove the tightness of this bound for some special cases which naturally generalize the |W⟩ state. A new lower bound on the tensor rank of the matrix permanent is also obtained by evaluating the tensor rank of Dicke states.
Khan, Majid; Naveed, Sadaf; Haider, Iqbal; Humayun, Mohammad; Khan, Abidullah
2017-03-01
Classic Raymond syndrome presents with abducens nerve palsy on the ipsilateral side with contralateral hemiparesis and facial nerve paralysis. A 60-year gentleman presented with deviation of left angle of mouth and right sided weakness. Examination showed that he had left sided abducens nerve palsy, with contralateral central facial paralysis and paresis. MRI of brain confirmed left pontine infarct. These findings were consistent with classic Raymond syndrome. Till now, only a few cases have been reported worldwide, this being the first case reported in South Asia. This case confirms that classic Raymond syndrome is different from the common type of Raymond syndrome in terms of sparing of coritcofacial fibers in the latter type.
NASA Astrophysics Data System (ADS)
Preoteasa, E. A.; Negoita, C.
2011-12-01
Starting from the concepts of the quantum electrodynamics (QED) theory of coherence domains (CD) in water we propose a model aimed to evaluate the relationship between the size and the living temperature limits for simple, small cells. Cells are described as spherical potential wells with impenetrable walls, with CDs moving inside. The radius of the spherical potential well was estimated for physiological temperatures and the results match to bacteria and yeasts cells' size. As a CD in the spherical cell exerts a force upon the membrane, a 'gas' formed by CDs bears a pressure on the walls. A classical statistical stability condition relates this pressure to cell volume and to the relative fluctuations of the CD number, allowing the evaluation of an upper temperature limit as a function of cellular volume. Assuming further that the CDs in the living cell form together a coherent state, the number-phase incertitude relationship (Heisenberg limit) applies. The maximum coherence between CDs is found in the ground state, a picture consistent also to Fröhlich's postulate. For a given phase dispersion, a lower temperature limit as a function of the cell volume is found. Although we neglected the rod-like shape of certain bacteria and the presence of nucleus in yeasts, the biological data of volume and optimal living temperature intervals fit well to our model's predictions. Moreover the larger the cell volume, the higher are the number of CDs and the coherence of their system. In addition we suggest a new classification criterion for small cells based on model's parameters, which show discontinuities between Gram negative and positive microorganisms as well as between prokaryotes and the smallest eukaryotes.
ERIC Educational Resources Information Center
Viswanathan, Jacqueline
1990-01-01
An approach that introduces a Quebec film into a college-level course for advanced students of French is described. The technique addresses three aspects of the film: organization; the significance of certain film-making processes; and cultural and social aspects of the film as they relate to Quebecoise culture. (MSE)
A Classical Science Transformed.
ERIC Educational Resources Information Center
Kovalevsky, Jean
1979-01-01
Describes how satellites and other tools of space technology have transformed classical geodesy into the science of space geodynamics. The establishment and the activities of the French Center for Geodynamic and Astronomical Research Studies (CERGA) are also included. (HM)
Illustrating the Classical Experiment.
ERIC Educational Resources Information Center
Zeller, Richard A.
1988-01-01
Describes an activity that (1) illustrates the classical experiment as a research tool; (2) demonstrates the interplay among hypotheses, methods, and data; and (3) nurtures the excitement of a method of study. (BSR)
A Classical Science Transformed.
ERIC Educational Resources Information Center
Kovalevsky, Jean
1979-01-01
Describes how satellites and other tools of space technology have transformed classical geodesy into the science of space geodynamics. The establishment and the activities of the French Center for Geodynamic and Astronomical Research Studies (CERGA) are also included. (HM)
NASA Astrophysics Data System (ADS)
Frimmer, Martin; Novotny, Lukas
2014-10-01
Coherent control of a quantum mechanical two-level system is at the heart of magnetic resonance imaging, quantum information processing, and quantum optics. Among the most prominent phenomena in quantum coherent control are Rabi oscillations, Ramsey fringes, and Hahn echoes. We demonstrate that these phenomena can be derived classically by use of a simple coupled-harmonic-oscillator model. The classical problem can be cast in a form that is formally equivalent to the quantum mechanical Bloch equations with the exception that the longitudinal and the transverse relaxation times (T1 and T2) are equal. The classical analysis is intuitive and well suited for familiarizing students with the basic concepts of quantum coherent control, while at the same time highlighting the fundamental differences between classical and quantum theories.
Innovation: the classic traps.
Kanter, Rosabeth Moss
2006-11-01
Never a fad, but always in or out of fashion, innovation gets rediscovered as a growth enabler every half dozen years. Too often, though, grand declarations about innovation are followed by mediocre execution that produces anemic results, and innovation groups are quietly disbanded in cost-cutting drives. Each managerial generation embarks on the same enthusiastic quest for the next new thing. And each generation faces the same vexing challenges- most of which stem from the tensions between protecting existing revenue streams critical to current success and supporting new concepts that may be crucial to future success. In this article, Harvard Business School professor Rosabeth Moss Kanter reflects on the four major waves of innovation enthusiasm she's observed over the past 25 years. She describes the classic mistakes companies make in innovation strategy, process, structure, and skills assessment, illustrating her points with a plethora of real-world examples--including AT&T Worldnet, Timberland, and Ocean Spray. A typical strategic blunder is when managers set their hurdles too high or limit the scope of their innovation efforts. Quaker Oats, for instance, was so busy in the 1990s making minor tweaks to its product formulas that it missed larger opportunities in distribution. A common process mistake is when managers strangle innovation efforts with the same rigid planning, budgeting, and reviewing approaches they use in their existing businesses--thereby discouraging people from adapting as circumstances warrant. Companies must be careful how they structure fledgling entities alongside existing ones, Kanter says, to avoid a clash of cultures and agendas--which Arrow Electronics experienced in its attempts to create an online venture. Finally, companies commonly undervalue and underinvest in the human side of innovation--for instance, promoting individuals out of innovation teams long before their efforts can pay off. Kanter offers practical advice for avoiding
NASA Technical Reports Server (NTRS)
Horzela, Andrzej; Kapuscik, Edward
1993-01-01
An alternative picture of classical many body mechanics is proposed. In this picture particles possess individual kinematics but are deprived from individual dynamics. Dynamics exists only for the many particle system as a whole. The theory is complete and allows to determine the trajectories of each particle. It is proposed to use our picture as a classical prototype for a realistic theory of confined particles.
Quantum vertex model for reversible classical computing
NASA Astrophysics Data System (ADS)
Chamon, C.; Mucciolo, E. R.; Ruckenstein, A. E.; Yang, Z.-C.
2017-05-01
Mappings of classical computation onto statistical mechanics models have led to remarkable successes in addressing some complex computational problems. However, such mappings display thermodynamic phase transitions that may prevent reaching solution even for easy problems known to be solvable in polynomial time. Here we map universal reversible classical computations onto a planar vertex model that exhibits no bulk classical thermodynamic phase transition, independent of the computational circuit. Within our approach the solution of the computation is encoded in the ground state of the vertex model and its complexity is reflected in the dynamics of the relaxation of the system to its ground state. We use thermal annealing with and without `learning' to explore typical computational problems. We also construct a mapping of the vertex model into the Chimera architecture of the D-Wave machine, initiating an approach to reversible classical computation based on state-of-the-art implementations of quantum annealing.
Quantum vertex model for reversible classical computing.
Chamon, C; Mucciolo, E R; Ruckenstein, A E; Yang, Z-C
2017-05-12
Mappings of classical computation onto statistical mechanics models have led to remarkable successes in addressing some complex computational problems. However, such mappings display thermodynamic phase transitions that may prevent reaching solution even for easy problems known to be solvable in polynomial time. Here we map universal reversible classical computations onto a planar vertex model that exhibits no bulk classical thermodynamic phase transition, independent of the computational circuit. Within our approach the solution of the computation is encoded in the ground state of the vertex model and its complexity is reflected in the dynamics of the relaxation of the system to its ground state. We use thermal annealing with and without 'learning' to explore typical computational problems. We also construct a mapping of the vertex model into the Chimera architecture of the D-Wave machine, initiating an approach to reversible classical computation based on state-of-the-art implementations of quantum annealing.
Quantum vertex model for reversible classical computing
Chamon, C.; Mucciolo, E. R.; Ruckenstein, A. E.; Yang, Z.-C.
2017-01-01
Mappings of classical computation onto statistical mechanics models have led to remarkable successes in addressing some complex computational problems. However, such mappings display thermodynamic phase transitions that may prevent reaching solution even for easy problems known to be solvable in polynomial time. Here we map universal reversible classical computations onto a planar vertex model that exhibits no bulk classical thermodynamic phase transition, independent of the computational circuit. Within our approach the solution of the computation is encoded in the ground state of the vertex model and its complexity is reflected in the dynamics of the relaxation of the system to its ground state. We use thermal annealing with and without ‘learning' to explore typical computational problems. We also construct a mapping of the vertex model into the Chimera architecture of the D-Wave machine, initiating an approach to reversible classical computation based on state-of-the-art implementations of quantum annealing. PMID:28497790
Familial classic trigeminal neuralgia.
Fernández Rodríguez, B; Simonet, C; Cerdán, D M; Morollón, N; Guerrero, P; Tabernero, C; Duarte, J
2017-03-24
The classic form of trigeminal neuralgia is usually sporadic (no familial clustering). However, around 2% of all cases of trigeminal neuralgia may be familial. Describing this entity may be useful for diagnosing this process and may also be key to determining the underlying causes of sporadic classical trigeminal neuralgia. We report on cases in a series of 5 families with at least 2 members with classic trigeminal neuralgia, amounting to a total of 11 cases. We recorded cases of familial classical trigeminal neuralgia between March 2014 and March 2015 by systematically interviewing all patients with a diagnosis of trigeminal neuralgia who visited the neurology department on an outpatient basis. In our sample, most patients with familial classic trigeminal neuralgia were women. Mean age at onset was 62.9±13.93 years, decreasing in subsequent generations. V2 was the most frequently affected branch. Most of our patients responded well to medical treatment, and surgery was not effective in all cases. These family clusters support the hypothesis that classic trigeminal neuralgia may have a genetic origin. Several causes have been suggested, including inherited anatomical changes affecting the base of the skull which would promote compression of the trigeminal nerve by vascular structures, familial AHT (resulting in tortuous vessels that would compress the trigeminal nerve), and mutations in the gene coding for calcium channels leading to hyperexcitability. Classic trigeminal neuralgia may be an autosomal dominant disorder displaying genetic anticipation. Copyright © 2017 The Author(s). Publicado por Elsevier España, S.L.U. All rights reserved.
Automatic target recognition via classical detection theory
NASA Astrophysics Data System (ADS)
Morgan, Douglas R.
1995-07-01
Classical Bayesian detection and decision theory applies to arbitrary problems with underlying probabilistic models. When the models describe uncertainties in target type, pose, geometry, surround, scattering phenomena, sensor behavior, and feature extraction, then classical theory directly yields detailed model-based automatic target recognition (ATR) techniques. This paper reviews options and considerations arising under a general Bayesian framework for model- based ATR, including approaches to the major problems of acquiring probabilistic models and of carrying out the indicated Bayesian computations.
Madsen, J R; Akabani, G
2014-05-07
The present state of modeling radio-induced effects at the cellular level does not account for the microscopic inhomogeneity of the nucleus from the non-aqueous contents (i.e. proteins, DNA) by approximating the entire cellular nucleus as a homogenous medium of water. Charged particle track-structure calculations utilizing this approximation are therefore neglecting to account for approximately 30% of the molecular variation within the nucleus. To truly understand what happens when biological matter is irradiated, charged particle track-structure calculations need detailed knowledge of the secondary electron cascade, resulting from interactions with not only the primary biological component-water--but also the non-aqueous contents, down to very low energies. This paper presents our work on a generic approach for calculating low-energy interaction cross-sections between incident charged particles and individual molecules. The purpose of our work is to develop a self-consistent computational method for predicting molecule-specific interaction cross-sections, such as the component molecules of DNA and proteins (i.e. nucleotides and amino acids), in the very low-energy regime. These results would then be applied in a track-structure code and thereby reduce the homogenous water approximation. The present methodology-inspired by seeking a combination of the accuracy of quantum mechanics and the scalability, robustness, and flexibility of Monte Carlo methods-begins with the calculation of a solution to the many-body Schrödinger equation and proceeds to use Monte Carlo methods to calculate the perturbations in the internal electron field to determine the interaction processes, such as ionization and excitation. As a test of our model, the approach is applied to a water molecule in the same method as it would be applied to a nucleotide or amino acid and compared with the low-energy cross-sections from the GEANT4-DNA physics package of the Geant4 simulation toolkit for the
Superintegrable classical Zernike system
NASA Astrophysics Data System (ADS)
Pogosyan, George S.; Wolf, Kurt Bernardo; Yakhno, Alexander
2017-07-01
We consider the differential equation that Zernike proposed to classify aberrations of wavefronts in a circular pupil, as if it were a classical Hamiltonian with a non-standard potential. The trajectories turn out to be closed ellipses. We show that this is due to the existence of higher-order invariants that close into a cubic Higgs algebra. The Zernike classical system thus belongs to the class of superintegrable systems. Its Hamilton-Jacobi action separates into three vertical projections of polar coordinates of sphere, polar, and equidistant coordinates on half-hyperboloids, and also in elliptic coordinates on the sphere.
Battistoni, P; Pezzoli, S; Bolzonella, D; Pavan, P
2002-01-01
The paper presents a comparison between the performances of two full scale wastewater treatment plants operating in Italy, considering the mass balances including P treatments, and results coming from an analysis of 16 similar plants in Europe and USA, in order to evaluate sludge overproduction due to chemical P removal adoption. Specific production of 9.5 and 12.5 kgTS/P.E.y were found for a BNR and denitrification plant scheme respectively. These results were compared, on a mass balance basis, with the performances coming from the adoption of the integrated waste/wastewater cycles, in which OFMSW fermentation is used as C source to promote BNR performances and P removal from anaerobic supernatants as struvite crystals. ASM2 simulations are used to verify the advantages coming from this approach in terms of sludge reduction. A complete mass balance of the process is carried out, and it is shown that this last process allows us to achieve the lowest sludge production among the processes considered, coupling this with the economic benefits coming from OFMSW disposal and struvite crystallisation.
NASA Astrophysics Data System (ADS)
Pollock, Steven
2013-04-01
At most universities, including the University of Colorado, upper-division physics courses are taught using a traditional lecture approach that does not make use of many of the instructional techniques that have been found to improve student learning at the introductory level. We are transforming several upper-division courses using principles of active engagement and learning theory, guided by the results of observations, interviews, and analysis of student work at CU and elsewhere. In this talk I outline these transformations, including the development of faculty consensus learning goals, clicker questions, tutorials, modified homeworks, and more. We present evidence of the effectiveness of these transformations relative to traditional courses, based on student grades, interviews, and through research-based assessments of student conceptual mastery and student attitudes. Our results suggest that many of the tools that have been effective in introductory courses are effective for our majors, and that further research is warranted in the upper-division environment. (See www.colorado.edu/sei/departments/physics.htm for materials)
NASA Astrophysics Data System (ADS)
Mandrà, Salvatore; Zhu, Zheng; Wang, Wenlong; Perdomo-Ortiz, Alejandro; Katzgraber, Helmut G.
2016-08-01
To date, a conclusive detection of quantum speedup remains elusive. Recently, a team by Google Inc. [V. S. Denchev et al., Phys. Rev. X 6, 031015 (2016), 10.1103/PhysRevX.6.031015] proposed a weak-strong cluster model tailored to have tall and narrow energy barriers separating local minima, with the aim to highlight the value of finite-range tunneling. More precisely, results from quantum Monte Carlo simulations as well as the D-Wave 2X quantum annealer scale considerably better than state-of-the-art simulated annealing simulations. Moreover, the D-Wave 2X quantum annealer is ˜108 times faster than simulated annealing on conventional computer hardware for problems with approximately 103 variables. Here, an overview of different sequential, nontailored, as well as specialized tailored algorithms on the Google instances is given. We show that the quantum speedup is limited to sequential approaches and study the typical complexity of the benchmark problems using insights from the study of spin glasses.
Milite, Ciro; Feoli, Alessandra; Sasaki, Kazuki; La Pietra, Valeria; Balzano, Amodio Luca; Marinelli, Luciana; Mai, Antonello; Novellino, Ettore; Castellano, Sabrina; Tosco, Alessandra; Sbardella, Gianluca
2015-03-26
Selective inhibitors of the two paralogue KAT3 acetyltransferases (CBP and p300) may serve not only as precious chemical tools to investigate the role of these enzymes in physiopathological mechanisms but also as lead structures for the development of further antitumor agents. After the application of a molecular pruning approach to the hardly optimizable and not very cell-permeable garcinol core structure, we prepared many analogues that were screened for their inhibitory effects using biochemical and biophysical (SPR) assays. Further optimization led to the discovery of the benzylidenebarbituric acid derivative 7h (EML425) as a potent and selective reversible inhibitor of CBP/p300, noncompetitive versus both acetyl-CoA and a histone H3 peptide, and endowed with good cell permeability. Furthermore, in human leukemia U937 cells, it induced a marked and time-dependent reduction in the acetylation of lysine H4K5 and H3K9, a marked arrest in the G0/G1 phase and a significant increase in the hypodiploid nuclei percentage.
ERIC Educational Resources Information Center
Alpers, Paul
1997-01-01
Addresses the question of what graduate students should know about fields of English in which they are not specializing. Finds the best answer is to teach "the classics." Illustrates with the example of a course on "The Faerie Queene" and "Paradise Lost," to show students how to work with texts and what can be…
ERIC Educational Resources Information Center
Karolides, Nicholas J., Ed.
1983-01-01
The articles in this journal issue suggest techniques for classroom use of literature that has "withstood the test of time." The titles of the articles and their authors are as follows: (1) "The Storytelling Connection for the Classics" (Mary Ellen Martin); (2) "Elizabeth Bennet: A Liberated Woman" (Geneva Marking);…
Children's Classics. Fifth Edition.
ERIC Educational Resources Information Center
Jordan, Alice M.
"Children's Classics," a 1947 article by Alice M. Jordan reprinted from "The Horn Book Magazine," examines the dynamics and appeal of some of the most famous books for young readers, including "Alice in Wonderland,""The Wind in the Willows,""Robinson Crusoe," and "Andersen's Fairy Tales." Paul Hein's annotated bibliography, a revision of Jordan's…
ERIC Educational Resources Information Center
Alpers, Paul
1997-01-01
Addresses the question of what graduate students should know about fields of English in which they are not specializing. Finds the best answer is to teach "the classics." Illustrates with the example of a course on "The Faerie Queene" and "Paradise Lost," to show students how to work with texts and what can be…
ERIC Educational Resources Information Center
Tighe, Mary Ann; Avinger, Charles
1994-01-01
Describes young adult novels that may prove to be classics of the genre. Discusses "The "Chocolate War" by Robert Cormier, "The Outsiders" by S. E. Hinton, "The Witch of Blackbird Pond" by Elizabeth George Speare, and "On Fortune's Wheel" by Cynthia Voight. (HB)
ERIC Educational Resources Information Center
Lum, Lydia
2005-01-01
America's few Black classics professors have overcome contempt and criticism to contribute a unique perspective to the study of the ancient world. Dr. Patrice Rankine, an associate professor from Purdue University, has grown used to the irony. As one of the few Black classicists teaching at an American university, he has drawn plenty of skepticism…
ERIC Educational Resources Information Center
Camic, Charles
2008-01-01
They seem the perfect bookends for the social psychologist's collection of "classics" of the field. Two volumes, nearly identical in shape and weight and exactly a century old in 2008--each professing to usher "social psychology" into the world as they both place the hybrid expression square in their titles but then proceed to stake out the field…
ERIC Educational Resources Information Center
Karolides, Nicholas J., Ed.
1983-01-01
The articles in this journal issue suggest techniques for classroom use of literature that has "withstood the test of time." The titles of the articles and their authors are as follows: (1) "The Storytelling Connection for the Classics" (Mary Ellen Martin); (2) "Elizabeth Bennet: A Liberated Woman" (Geneva Marking);…
Children's Classics. Fifth Edition.
ERIC Educational Resources Information Center
Jordan, Alice M.
"Children's Classics," a 1947 article by Alice M. Jordan reprinted from "The Horn Book Magazine," examines the dynamics and appeal of some of the most famous books for young readers, including "Alice in Wonderland,""The Wind in the Willows,""Robinson Crusoe," and "Andersen's Fairy Tales." Paul Hein's annotated bibliography, a revision of Jordan's…
ERIC Educational Resources Information Center
Huddleston, Gregory H.
1993-01-01
Describes one teacher's methods for introducing to secondary English students the concepts of Classicism and Romanticism in relation to pictures of gardens, architecture, music, and literary works. Outlines how the unit leads to a writing assignment based on collected responses over time. (HB)
Classical Mythology. Fourth Edition.
ERIC Educational Resources Information Center
Morford, Mark P. O.; Lenardon, Robert J.
Designed for students with little or no background in classical literature, this book introduces the Greek and Roman myths of creation, myths of the gods, Greek sagas and local legends, and presents contemporary theories about the myths. Drawing on Homer, Hesiod, Pindar, Vergil, and others, the book provides many translations and paraphrases of…
ERIC Educational Resources Information Center
Camic, Charles
2008-01-01
They seem the perfect bookends for the social psychologist's collection of "classics" of the field. Two volumes, nearly identical in shape and weight and exactly a century old in 2008--each professing to usher "social psychology" into the world as they both place the hybrid expression square in their titles but then proceed to stake out the field…
ERIC Educational Resources Information Center
Huddleston, Gregory H.
1993-01-01
Describes one teacher's methods for introducing to secondary English students the concepts of Classicism and Romanticism in relation to pictures of gardens, architecture, music, and literary works. Outlines how the unit leads to a writing assignment based on collected responses over time. (HB)
Classical galactosaemia revisited.
Bosch, Annet M
2006-08-01
Classical galactosaemia (McKusick 230400) is an: autosomal recessive disorder of galactose metabolism, caused by a deficiency of the enzyme galactose-1-phosphate uridyltransferase (GALT; EC 2.7.712). Most patients present in the neonatal period, after ingestion of galactose, with jaundice, hepatosplenomegaly, hepatocellular insufficiency, food intolerance, hypoglycaemia, renal tubular dysfunction, muscle hypotonia, sepsis and cataract. The gold standard for diagnosis of classical galactosaemia is measurement of GALT activity in erythrocytes. Gas-chromatographic determination of urinary sugars and sugar alcohols demonstrates elevated concentrations of galactose and galactitol. The only therapy for patients with classical galactosaemia is a galactose-restricted diet, and initially all galactose must be removed from the diet as soon as the diagnosis is suspected. After the neonatal period, a lactose-free diet is advised in most countries, without restriction of galactose-containing fruit and vegetables. In spite of the strict diet, long-term complications such as retarded mental development, verbal dyspraxia, motor abnormalities and hypergonadotrophic hypogonadism are frequently seen in patients with classical galactosaemia. It has been suggested that these complications may result from endogenous galactose synthesis or from abnormal galactosylation. Novel therapeutic strategies, aiming at the prevention of galactose 1-phosphate production, should be developed. In the meantime, the follow-up protocol for patients with GALT deficiency should focus on early detection, evaluation and, if possible, early intervention in problems of motor, speech and cognitive development.
Observations of classical cepheids
NASA Technical Reports Server (NTRS)
Pel, J. W.
1980-01-01
The observations of classical Cepheids are reviewed. The main progress that has been made is summarized and some of the problems yet to be solved are discussed. The problems include color excesses, calibration of color, duplicity, ultraviolet colors, temperature-color relations, mass discrepancies, and radius determination.
Classical Demonstration of Polarization.
ERIC Educational Resources Information Center
Bauman, Robert P.; Moore, Dennis R.
1980-01-01
Presents a classical demonstration of polarization for high school students. The initial state of this model, which demonstrates the important concepts of the optical and quantum problems, was developed during the 1973 summer program on lecture demonstration at the U.S. Naval Academy. (HM)
Classical Mythology. Fourth Edition.
ERIC Educational Resources Information Center
Morford, Mark P. O.; Lenardon, Robert J.
Designed for students with little or no background in classical literature, this book introduces the Greek and Roman myths of creation, myths of the gods, Greek sagas and local legends, and presents contemporary theories about the myths. Drawing on Homer, Hesiod, Pindar, Vergil, and others, the book provides many translations and paraphrases of…
ERIC Educational Resources Information Center
Tighe, Mary Ann; Avinger, Charles
1994-01-01
Describes young adult novels that may prove to be classics of the genre. Discusses "The "Chocolate War" by Robert Cormier, "The Outsiders" by S. E. Hinton, "The Witch of Blackbird Pond" by Elizabeth George Speare, and "On Fortune's Wheel" by Cynthia Voight. (HB)
Quantization of soluble classical constrained systems
Belhadi, Z.; Menas, F.; Bérard, A.; Mohrbach, H.
2014-12-15
The derivation of the brackets among coordinates and momenta for classical constrained systems is a necessary step toward their quantization. Here we present a new approach for the determination of the classical brackets which does neither require Dirac’s formalism nor the symplectic method of Faddeev and Jackiw. This approach is based on the computation of the brackets between the constants of integration of the exact solutions of the equations of motion. From them all brackets of the dynamical variables of the system can be deduced in a straightforward way.
Moennig, V; Becher, P; Beer, M
2013-01-01
Classical swine fever is a serious and economically important transboundary disease threatening pig production globally. The infection may occur in backyard pigs, feral pig populations and domestic pigs. Whereas there are proven control strategies for the latter pig population, control in backyard pigs with poor biosecurity settings or in wild boar populations of high density still poses a problem in some parts of the world. Laboratory diagnostic methods, efficacious vaccines and contingency plans are in place in most industrialised countries. So far modified live vaccines (MLV) are still the first choice for rapid and reliable immune protection. Since antibodies elicited by conventional MLV cannot be distinguished from antibodies after natural infection, considerable efforts are put into the development of a live marker vaccine accompanied by a serological test. Nevertheless, some remaining gaps with respect to the diagnosis of and vaccination against classical swine fever have been identified.
Classical versus quantum gravity
Drechsler, W. )
1993-02-01
Is Einstein's metric theory of gravitation to be quantized to yield a complete and logically consistent picture of the geometry of the real world in the presence of quantized material sources To answer this question, we give arguments that there is a consistent way to extent general relativity to small distances by incorporating further geometric quantities at the level of the connection into the theory and introducing corresponding field equations for their determination, allowing thereby the metric and the Levi-Civita connection to remain classical quantities. The dualism between matter and geometry is extended to quantized fields with the help of Hilbert bundle H raised over a Riemann-Cartan spacetime. Quantized subnuclear matter fields (generalized quantum mechanical wave functions) are sections on H which determine generalized bilinear currents acting as source currents for the bundle geometry at small distances. The established dualism between matter and the underling bundle geometry contains general relatively as a classical part.
NASA Astrophysics Data System (ADS)
Iselin, F. Christoph
1997-02-01
Exchange of data and algorithms among accelerator physics programs is difficult because of unnecessary differences in input formats and internal data structures. To alleviate these problems a C++ class library called CLASSIC (Class Library for Accelerator System Simulation and Control) is being developed with the goal to provide standard building blocks for computer programs used in accelerator design. It includes modules for building accelerator lattice structures in computer memory using a standard input language, a graphical user interface, or a programmed algorithm. It also provides simulation algorithms. These can easily be replaced by modules which communicate with the control system of the accelerator. Exchange of both data and algorithm between different programs using the CLASSIC library should present no difficulty.
Ollerton, Joanne Emma; Sugrue, Michael
2005-02-01
The evolution of trauma may be analyzed by review of articles most frequently cited by scientific articles worldwide. This study identified the "trauma classics" by reviewing the most-cited articles ever published in The Journal of Trauma. The Science Citation Index of the Institute for Scientific Information was searched for the 50 most-cited articles in The Journal of Trauma. Of the 12,672 articles published since 1961, 80 were cited over 100 times and 17 over 200 times. The most-cited article was by Baker, a hallmark publication on injury scoring published in 1974. Feeding postinjury, bacterial translocation, and multiple organ failure were common themes. Overall, 32% involved gastrointestinal topics and 18% involved injury scoring, with institutions in the United States publishing 80% of the articles. This study identified the trauma classics from the last 42 years of The Journal of Trauma. Citation analysis has recognized limitations but gives a fascinating insight into the evolution of trauma care.
Classical Weyl transverse gravity
NASA Astrophysics Data System (ADS)
Oda, Ichiro
2017-05-01
We study various classical aspects of the Weyl transverse (WTDiff) gravity in a general space-time dimension. First of all, we clarify a classical equivalence among three kinds of gravitational theories, those are, the conformally invariant scalar tensor gravity, Einstein's general relativity and the WTDiff gravity via the gauge-fixing procedure. Secondly, we show that in the WTDiff gravity the cosmological constant is a mere integration constant as in unimodular gravity, but it does not receive any radiative corrections unlike the unimodular gravity. A key point in this proof is to construct a covariantly conserved energy-momentum tensor, which is achieved on the basis of this equivalence relation. Thirdly, we demonstrate that the Noether current for the Weyl transformation is identically vanishing, thereby implying that the Weyl symmetry existing in both the conformally invariant scalar tensor gravity and the WTDiff gravity is a "fake" symmetry. We find it possible to extend this proof to all matter fields, i.e. the Weyl-invariant scalar, vector and spinor fields. Fourthly, it is explicitly shown that in the WTDiff gravity the Schwarzschild black hole metric and a charged black hole one are classical solutions to the equations of motion only when they are expressed in the Cartesian coordinate system. Finally, we consider the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology and provide some exact solutions.
Classical Vs. Superfluid Turbulence
NASA Astrophysics Data System (ADS)
Roche, P.-E.
2008-11-01
Thanks to a zero-viscosity, superfluids offer a unique testing ground for hydrodynamic models, in particular for turbulence ones. In Kolmogorov's turbulence model, viscosity is well known to damp the kinetic energy of the smallest eddies, and thus to introduce a cut-off at one end of the turbulent cascade. Significant differences between this ``classical'' turbulence and the turbulence of a superfluid are therefore expected, but --surprisingly- most experiments rather evidenced strong similarities. We will give an overview of a set of experiments designed to compare in details the classical versus superfluid turbulences, up to a record mass flow of superfluid (700g/s of He @ 1.6K). Then, we will focus on some unexpected vorticity measurements, which can be interpreted assuming that the superfluid vortices are passively advected by the largest scales of the flow, in contrast with the ``classical'' turbulence counterpart. Numerical simulations -based on regular DNS- will be presented to complete this interpretation. In collaboration with C. Barenghi, University of Newcastle; B. Castaing and E. Levèque, ENSL, Lyon; S. David, IEF, CNRS, Orsay; B. Rousset, SBT/CEA, Grenoble; and P. Tabeling, H. Willaime MMN, ESPCI, Paris.
Entanglement with classical fields
Lee, K.F.; Thomas, J.E.
2004-05-01
We experimentally demonstrate a simple classical-field optical heterodyne method which employs postselection to reproduce the polarization correlations of a four-particle entangled state. We give a heuristic argument relating this method to the measurement of multiple quantum fields by correlated homodyne detection. We suggest that using multiple classical fields and postselection, one can reproduce the polarization correlations obtained in quantum experiments which employ multiple single-photon sources and linear optics to prepare multiparticle entangled states. Our experimental scheme produces four spatially separated beams which are separately detected by mixing with four independent optical local oscillators (LO) of variable polarization. Analog multiplication of the four beat signals enables projection onto a four-particle polarization-state basis. Appropriate band pass filtering is used to produce a signal proportional to the projections of the maximally entangled four-field polarization state, H{sub 1})H{sub 2})H{sub 3})H{sub 4})+V{sub 1})V{sub 2})V{sub 3})V{sub 4}), onto the product of the four LO polarizations. Since the data from multiple observers is combined prior to postselection, this method does not constitute a test of nonlocality. However, we reproduce the polarization correlations of the 32 elements in the truth table from the quantum mechanical Greenberger-Horne-Zeilinger experiments on the violation of local realism. We also demonstrate a form of classical entanglement swapping in a four-particle basis.
Classical and Contemporary Approaches for Moral Development
ERIC Educational Resources Information Center
Cam, Zekeriya; Seydoogullari, Sedef; Cavdar, Duygu; Cok, Figen
2012-01-01
Most of the information in the moral development literature depends on Theories of Piaget and Kohlberg. The theoretical contribution by Gilligan and Turiel are not widely known and not much resource is available in Turkish. For this reason introducing and discussing the theories of Gilligan and Turiel and more comprehensive perspective for moral…
Exchange potentials for semi-classical electrons.
Herzfeld, Judith; Ekesan, Solen
2016-11-09
Semi-classical electrons offer access to efficient and intuitive simulations of chemical reactions. As for any treatment of fermions, the greatest difficulty is in accounting for anti-symmetry effects. Semi-classical efforts to-date either reference Slater-determinants from ab initio treatments or adopt a heuristic approach inspired by density functional treatments. Here we revisit the problem with a combined approach. We conclude that semi-classical electrons need to reference a non-conventional wave function and find that (1) contrary to earlier suppositions, contributions from the electrostatic terms in the Hamiltonian are of similar magnitude to those from the kinetic terms and (2) the former point to a need to supplement pair potentials with 3-body potentials. The first result explains features of reported heuristic potentials, and the second provides a firm footing for extending the transferability of potentials across a wider range of elements and bonding scenarios.
Machian classical and semiclassical emergent time
NASA Astrophysics Data System (ADS)
Anderson, Edward
2014-01-01
Classical and semiclassical schemes are presented that are timeless at the primary level and recover time from Mach’s ‘time is to be abstracted from change’ principle at the emergent secondary level. The semiclassical scheme is a Machian variant of the semiclassical approach to the problem of time in quantum gravity. The classical scheme is Barbour’s, cast here explicitly as the classical precursor of the semiclassical approach. Thus the two schemes have been married up, as equally-Machian and necessarily distinct, since the latter’s timestandard is abstracted in part from quantum change. I provide perturbative schemes for these in which the timefunction is to be determined rather than assumed. This paper is useful modelling as regards the Halliwell-Hawking arena for the quantum origin of the inhomogeneous cosmological fluctuations.
Vázquez-Mayagoitia, Álvaro; Ratcliff, Laura E.; Tretiak, Sergei; Bair, Raymond A.; Gray, Stephen K.; Van Voorhis, Troy; Larsen, Ross E.; Darling, Seth B.
2017-01-01
Organic photovoltaics (OPVs) are a promising carbon-neutral energy conversion technology, with recent improvements pushing power conversion efficiencies over 10%. A major factor limiting OPV performance is inefficiency of charge transport in organic semiconducting materials (OSCs). Due to strong coupling with lattice degrees of freedom, the charges form polarons, localized quasi-particles comprised of charges dressed with phonons. These polarons can be conceptualized as pseudo-atoms with a greater effective mass than a bare charge. We propose that due to this increased mass, polarons can be modeled with Langevin molecular dynamics (LMD), a classical approach with a computational cost much lower than most quantum mechanical methods. Here we present LMD simulations of charge transfer between a pair of fullerene molecules, which commonly serve as electron acceptors in OSCs. We find transfer rates consistent with experimental measurements of charge mobility, suggesting that this method may provide quantitative predictions of efficiency when used to simulate materials on the device scale. Our approach also offers information that is not captured in the overall transfer rate or mobility: in the simulation data, we observe exactly when and why intermolecular transfer events occur. In addition, we demonstrate that these simulations can shed light on the properties of polarons in OSCs. Much remains to be learned about these quasi-particles, and there are no widely accepted methods for calculating properties such as effective mass and friction. Our model offers a promising approach to exploring mass and friction as well as providing insight into the details of polaron transport in OSCs. PMID:28553494
Quantum and Classical Electrostatics Among Atoms
NASA Astrophysics Data System (ADS)
Doerr, T. P.; Obolensky, O. I.; Ogurtsov, A. Y.; Yu, Yi-Kuo
Quantum theory has been unquestionably successful at describing physics at the atomic scale. However, it becomes more difficult to apply as the system size grows. On the other hand, classical physics breaks down at sufficiently short length scales but is clearly correct at larger distances. The purpose of methods such as QM/MM is to gain the advantages of both quantum and classical regimes: quantum theory should provide accuracy at the shortest scales, and classical theory, with its somewhat more tractable computational demands, allows results to be computed for systems that would be inaccessible with a purely quantum approach. This strategy will be most effective when one knows with good accuracy the length scale at which quantum calculations are no longer necessary and classical calculations are sufficient. To this end, we have performed both classical and quantum calculations for systems comprising a small number of atoms for which experimental data is also available. The classical calculations are fully exact; the quantum calculations are at the MP4(SDTQ)/aug-cc-pV5Z and CCSD(T)/aug-cc-pV5Z levels. The precision of both sets of calculations along with the existence of experimental results allows us to draw conclusions about the range of utility of the respective calculations. This research was supported by the Intramural Research Program of the NIH, NLM and utilized the computational resources of the NIH HPC Biowulf cluster.
Classic Radio Theatre in Contemporary Education.
ERIC Educational Resources Information Center
West, Keith
Radio theater production has been a component of secondary and post-secondary education since the late 1920s. Since the reduction in radio theater in the 1950s, such courses have been used to prepare students for other fields--television, film, etc. Radio theater production can be approached in two ways: classic production and modern production.…
Stark, Julian; Brandner, Kay; Saito, Keiji; Seifert, Udo
2014-04-11
We introduce a simple model for an engine based on the Nernst effect. In the presence of a magnetic field, a vertical heat current can drive a horizontal particle current against a chemical potential. For a microscopic model invoking classical particle trajectories subject to the Lorentz force, we prove a universal bound 3-2√2≃0.172 for the ratio between the maximum efficiency and the Carnot efficiency. This bound, as the slightly lower one 1/6 for efficiency at maximum power, can indeed be saturated for a large magnetic field and small fugacity.
Un-renormalized classical electromagnetism
Ibison, Michael . E-mail: ibison@earthtech.org
2006-02-15
This paper follows in the tradition of direct-action versions of electromagnetism having the aim of avoiding a balance of infinities wherein a mechanical mass offsets an infinite electromagnetic mass so as to arrive at a finite observed value. However, the direct-action approach ultimately failed in that respect because its initial exclusion of self-action was later found to be untenable in the relativistic domain. Pursing the same end, this paper examines instead a version of electromagnetism wherein mechanical action is excluded and self-action is retained. It is shown that the resulting theory is effectively interacting due to the presence of infinite forces. A vehicle for the investigation is a pair of classical point charges in a positronium-like arrangement for which the orbits are found to be self-sustaining and naturally quantized.
GALK inhibitors for classic galactosemia.
Lai, Kent; Boxer, Matthew B; Marabotti, Anna
2014-06-01
Classic galactosemia is an inherited metabolic disease for which, at present, no therapy is available apart from galactose-restricted diet. However, the efficacy of the diet is questionable, since it is not able to prevent the insurgence of chronic complications later in life. In addition, it is possible that dietary restriction itself could induce negative side effects. Therefore, there is a need for an alternative therapeutic approach that can avert the manifestation of chronic complications in the patients. In this review, the authors describe the development of a novel class of pharmaceutical agents that target the production of a toxic metabolite, galactose-1-phosphate, considered as the main culprit for the cause of the complications, in the patients.
Hoffmann, Sabine; Rage, Estelle; Laurier, Dominique; Laroche, Pierre; Guihenneuc, Chantal; Ancelet, Sophie
2017-02-01
Many occupational cohort studies on underground miners have demonstrated that radon exposure is associated with an increased risk of lung cancer mortality. However, despite the deleterious consequences of exposure measurement error on statistical inference, these analyses traditionally do not account for exposure uncertainty. This might be due to the challenging nature of measurement error resulting from imperfect surrogate measures of radon exposure. Indeed, we are typically faced with exposure uncertainty in a time-varying exposure variable where both the type and the magnitude of error may depend on period of exposure. To address the challenge of accounting for multiplicative and heteroscedastic measurement error that may be of Berkson or classical nature, depending on the year of exposure, we opted for a Bayesian structural approach, which is arguably the most flexible method to account for uncertainty in exposure assessment. We assessed the association between occupational radon exposure and lung cancer mortality in the French cohort of uranium miners and found the impact of uncorrelated multiplicative measurement error to be of marginal importance. However, our findings indicate that the retrospective nature of exposure assessment that occurred in the earliest years of mining of this cohort as well as many other cohorts of underground miners might lead to an attenuation of the exposure-risk relationship. More research is needed to address further uncertainties in the calculation of lung dose, since this step will likely introduce important sources of shared uncertainty.
Are all measurement outcomes "classical"?
NASA Astrophysics Data System (ADS)
Bächtold, Manuel
In Bohr's view, all measurement outcomes, even in microphysics, are "classical" because they are expressed by means of the concepts of classical physics (or by everyday concepts refined by classical physics). This paper provides a careful analysis of Bohr's arguments in favour of this claim; the one concerning the possibility of using classical concepts so as to express the measurement outcomes, and the one concerning its necessity. Both arguments are shown to fail. Nevertheless, it appears that the concepts which are in fact used for the description of the measurement outcomes in microphysics originate from classical physics and the scales associated with the measured observables are extensions of the ones associated with the classical physical magnitudes. In this respect, the measurement outcomes in microphysics can be considered as "classical" by reference to classical physics only in a narrow sense.
Fano Interference in Classical Oscillators
ERIC Educational Resources Information Center
Satpathy, S.; Roy, A.; Mohapatra, A.
2012-01-01
We seek to illustrate Fano interference in a classical coupled oscillator by using classical analogues of the atom-laser interaction. We present an analogy between the dressed state picture of coherent atom-laser interaction and a classical coupled oscillator. The Autler-Townes splitting due to the atom-laser interaction is analogous to the…
Classical Trajectories and Quantum Spectra
NASA Technical Reports Server (NTRS)
Mielnik, Bogdan; Reyes, Marco A.
1996-01-01
A classical model of the Schrodinger's wave packet is considered. The problem of finding the energy levels corresponds to a classical manipulation game. It leads to an approximate but non-perturbative method of finding the eigenvalues, exploring the bifurcations of classical trajectories. The role of squeezing turns out decisive in the generation of the discrete spectra.
Fano Interference in Classical Oscillators
ERIC Educational Resources Information Center
Satpathy, S.; Roy, A.; Mohapatra, A.
2012-01-01
We seek to illustrate Fano interference in a classical coupled oscillator by using classical analogues of the atom-laser interaction. We present an analogy between the dressed state picture of coherent atom-laser interaction and a classical coupled oscillator. The Autler-Townes splitting due to the atom-laser interaction is analogous to the…
Classical Physics and Quantum Loops
Barry R. Holstein; John F. Donoghue
2004-05-01
The standard picture of the loop expansion associates a factor of h-bar with each loop, suggesting that the tree diagrams are to be associated with classical physics, while loop effects are quantum mechanical in nature. We discuss examples wherein classical effects arise from loop contributions and display the relationship between the classical terms and the long range effects of massless particles.
Communication: quantum dynamics in classical spin baths.
Sergi, Alessandro
2013-07-21
A formalism for studying the dynamics of quantum systems embedded in classical spin baths is introduced. The theory is based on generalized antisymmetric brackets and predicts the presence of open-path off-diagonal geometric phases in the evolution of the density matrix. The weak coupling limit of the equation can be integrated by standard algorithms and provides a non-Markovian approach to the computer simulation of quantum systems in classical spin environments. It is expected that the theory and numerical schemes presented here have a wide applicability.
Communication: Quantum dynamics in classical spin baths
NASA Astrophysics Data System (ADS)
Sergi, Alessandro
2013-07-01
A formalism for studying the dynamics of quantum systems embedded in classical spin baths is introduced. The theory is based on generalized antisymmetric brackets and predicts the presence of open-path off-diagonal geometric phases in the evolution of the density matrix. The weak coupling limit of the equation can be integrated by standard algorithms and provides a non-Markovian approach to the computer simulation of quantum systems in classical spin environments. It is expected that the theory and numerical schemes presented here have a wide applicability.
Decoherence, chaos, the quantum and the classical
Zurek, W.H.; Paz, J.P.
1994-04-01
The key ideas of the environment-induced decoherence approach are reviewed. Application of decoherence to the transition from quantum to classical in open quantum systems with chaotic classical analogs is described. The arrow of time is, in this context, a result of the information loss to the correlations with the environment. The asymptotic rate of entropy production (which is reached quickly, on the dynamical timescale) is independent of the details of the coupling of the quantum system to the environment, and is set by the Lyapunov exponents. We also briefly outline the existential interpretation of quantum mechanics, justifying the slogan ``No information without representation.``
Perspective: Quantum or classical coherence?
Miller, William H
2012-06-07
Some coherence effects in chemical dynamics are described correctly by classical mechanics, while others only appear in a quantum treatment--and when these are observed experimentally it is not always immediately obvious whether their origin is classical or quantum. Semiclassical theory provides a systematic way of adding quantum coherence to classical molecular dynamics and thus provides a useful way to distinguish between classical and quantum coherence. Several examples are discussed which illustrate both cases. Particularly interesting is the situation with electronically non-adiabatic processes, where sometimes whether the coherence effects are classical or quantum depends on what specific aspects of the process are observed.
Quantum backreaction on classical dynamics
NASA Astrophysics Data System (ADS)
Vachaspati, Tanmay
2017-06-01
Motivated by various systems in which quantum effects occur in classical backgrounds, we consider the dynamics of a classical particle as described by a coherent state that is coupled to a quantum bath via biquadratic interactions. We evaluate the resulting quantum dissipation of the motion of the classical particle. We also find classical initial conditions for the bath that effectively lead to the same dissipation as that due to quantum effects, possibly providing a way to approximately account for quantum backreaction within a classical analysis.
Supersymmetric classical cosmology
Escamilla-Rivera, Celia; Obregón, Octavio; Ureña-López, L. Arturo E-mail: octavio@fisica.ugto.mx
2010-12-01
In this work a supersymmetric cosmological model is analyzed in which we consider a general superfield action of a homogeneous scalar field supermultiplet interacting with the scale factor in a supersymmetric FRW model. There appear fermionic superpartners associated with both the scale factor and the scalar field, and classical equations of motion are obtained from the super-Wheeler-DeWitt equation through the usual WKB method. The resulting supersymmetric Einstein-Klein-Gordon equations contain extra radiation and stiff matter terms, and we study their solutions in flat space for different scalar field potentials. The solutions are compared to the standard case, in particular those corresponding to the exponential potential, and their implications for the dynamics of the early Universe are discussed in turn.
NASA Astrophysics Data System (ADS)
Boyer, T. H.
1985-08-01
The history of vacuum concepts is reviewed, noting that no way is known to physically produce a true void. Even at absolute zero, a pattern of electromagnetic wave fluctuations are still present. The fluctuations are called zero-point radiation (ZPR). To be invariant to Lorentz transformation, ZPR has a spectral intensity proportional to the cube of each frequency. ZPR does not change in response to compression and produces a force between objects that is inversely proportional to the 4th power of the separation distance. The ZPR scale value has been measured to be one-half of the Planck constant, and is the measure of the energy of a harmonic oscillator, such as the electron, in a vacuum. Finally, since gravitational accelerations always occur in the physical space, a minimum thermal radiation can also be found for the vacuum, implying that a fixed relationship exists between thermal radiation and the classical vacuum.
Moskalik, P.; Buchler, J.R.; Kovacs, G. )
1990-12-01
Theoretical models of classical Cepheid variable stars are examined by means of test computations focusing on (1) the systematic period change known as the Hertzsprung or bump progression and (2) the hypothesis (Simon and Schmidt, 1976) that (1) is due to a 2:1 resonance between the fundamental mode and the second overtone. One-parameter families or sequences of models are calculated which represent 'snapshots' of pulsational behavior at different points on the Cepheid evolutionary tracks, and a remarkable uniformity is found when the Fourier coefficients for sequences with moderate luminosity/mass ratios are plottted against the linear period ratio. The complete disappearance of this uniformity when the coefficients are plotted against the pulsation period itself is shown to be consistent with (2). The description of these phenomena with amplitude equations is explained, and expressions for estimating the width of the instability strip are derived. 32 refs.
Supersymmetry in classical mechanics
NASA Astrophysics Data System (ADS)
Suen, W. M.; Wong, C. W.; Young, K.
2000-06-01
The concept of supersymmetry extended to classical mechanics relates one-parameter families of Hamiltonians H( ξ, x, p)= p2+ V( ξ, x), such that the mapping from the phase space of H( ξ1, x, p) to that of H( ξ2, x, p) preserves time-evolution and conserves total energy; as a result, equal-energy periodic orbits in the two have the same period. While t-evolution is a contact transformation generated by H, ξ-evolution is a generalized contact transformation generated by a function K, and preserves phase volume except for a point sink (source) as ξ increases (decreases). Closed-form solutions of ξ-evolution include several well-known examples.
NASA Astrophysics Data System (ADS)
Sbisà, Fulvio
2015-01-01
The aim of these notes is to provide a self-contained review of why it is generically a problem when a solution of a theory possesses ghost fields among the perturbation modes. We define what a ghost field is and we show that its presence is associated with a classical instability whenever the ghost field interacts with standard fields. We then show that the instability is more severe at quantum level, and that perturbative ghosts can exist only in low energy effective theories. However, if we do not consider very ad hoc choices, compatibility with observational constraints implies that low energy effective ghosts can exist only at the price of giving up Lorentz invariance or locality above the cut-off, in which case the cut-off has to be much lower that the energy scales we currently probe in particle colliders. We also comment on the possible role of extra degrees of freedom which break Lorentz invariance spontaneously.
Quantum transitions between classical histories
NASA Astrophysics Data System (ADS)
Hartle, James; Hertog, Thomas
2015-09-01
In a quantum theory of gravity spacetime behaves classically when quantum probabilities are high for histories of geometry and field that are correlated in time by the Einstein equation. Probabilities follow from the quantum state. This quantum perspective on classicality has important implications. (a) Classical histories are generally available only in limited patches of the configuration space on which the state lives. (b) In a given patch, states generally predict relative probabilities for an ensemble of possible classical histories. (c) In between patches classical predictability breaks down and is replaced by quantum evolution connecting classical histories in different patches. (d) Classical predictability can break down on scales well below the Planck scale, and with no breakdown in the classical equations of motion. We support and illustrate (a)-(d) by calculating the quantum transition across the de Sitter-like throat connecting asymptotically classical, inflating histories in the no-boundary quantum state. This supplies probabilities for how a classical history on one side transitions and branches into a range of classical histories on the opposite side. We also comment on the implications of (a)-(d) for the dynamics of black holes and eternal inflation.
Nonlinear atom interferometer surpasses classical precision limit.
Gross, C; Zibold, T; Nicklas, E; Estève, J; Oberthaler, M K
2010-04-22
Interference is fundamental to wave dynamics and quantum mechanics. The quantum wave properties of particles are exploited in metrology using atom interferometers, allowing for high-precision inertia measurements. Furthermore, the state-of-the-art time standard is based on an interferometric technique known as Ramsey spectroscopy. However, the precision of an interferometer is limited by classical statistics owing to the finite number of atoms used to deduce the quantity of interest. Here we show experimentally that the classical precision limit can be surpassed using nonlinear atom interferometry with a Bose-Einstein condensate. Controlled interactions between the atoms lead to non-classical entangled states within the interferometer; this represents an alternative approach to the use of non-classical input states. Extending quantum interferometry to the regime of large atom number, we find that phase sensitivity is enhanced by 15 per cent relative to that in an ideal classical measurement. Our nonlinear atomic beam splitter follows the 'one-axis-twisting' scheme and implements interaction control using a narrow Feshbach resonance. We perform noise tomography of the quantum state within the interferometer and detect coherent spin squeezing with a squeezing factor of -8.2 dB (refs 11-15). The results provide information on the many-particle quantum state, and imply the entanglement of 170 atoms.
Population structure of the Classic period Maya.
Scherer, Andrew K
2007-03-01
This study examines the population structure of Classic period (A.D. 250-900) Maya populations through analysis of odontometric variation of 827 skeletons from 12 archaeological sites in Mexico, Guatemala, Belize, and Honduras. The hypothesis that isolation by distance characterized Classic period Maya population structure is tested using Relethford and Blangero's (Hum Biol 62 (1990) 5-25) approach to R matrix analysis for quantitative traits. These results provide important biological data for understanding ancient Maya population history, particularly the effects of the competing Tikal and Calakmul hegemonies on patterns of lowland Maya site interaction. An overall F(ST) of 0.018 is found for the Maya area, indicating little among-group variation for the Classic Maya sites tested. Principal coordinates plots derived from the R matrix analysis show little regional patterning in the data, though the geographic outliers of Kaminaljuyu and a pooled Pacific Coast sample did not cluster with the lowland Maya sites. Mantel tests comparing the biological distance matrix to a geographic distance matrix found no association between genetic and geographic distance. In the Relethford-Blangero analysis, most sites possess negative or near-zero residuals, indicating minimal extraregional gene flow. The exceptions were Barton Ramie, Kaminaljuyu, and Seibal. A scaled R matrix analysis clarifies that genetic drift is a consideration for understanding Classic Maya population structure. All results indicate that isolation by distance does not describe Classic period Maya population structure. (c) 2006 Wiley-Liss, Inc.
Quantum Computing's Classical Problem, Classical Computing's Quantum Problem
NASA Astrophysics Data System (ADS)
Van Meter, Rodney
2014-08-01
Tasked with the challenge to build better and better computers, quantum computing and classical computing face the same conundrum: the success of classical computing systems. Small quantum computing systems have been demonstrated, and intermediate-scale systems are on the horizon, capable of calculating numeric results or simulating physical systems far beyond what humans can do by hand. However, to be commercially viable, they must surpass what our wildly successful, highly advanced classical computers can already do. At the same time, those classical computers continue to advance, but those advances are now constrained by thermodynamics, and will soon be limited by the discrete nature of atomic matter and ultimately quantum effects. Technological advances benefit both quantum and classical machinery, altering the competitive landscape. Can we build quantum computing systems that out-compute classical systems capable of some logic gates per month? This article will discuss the interplay in these competing and cooperating technological trends.
Nechansky, A; Szolar, O H J; Siegl, P; Zinoecker, I; Halanek, N; Wiederkum, S; Kircheis, R
2009-05-01
The fully humanized Lewis-Y carbohydrate specific monoclonal antibody (mAb) IGN311 is currently tested in a passive immunotherapy approach in a clinical phase I trail and therefore regulatory requirements demand qualified assays for product analysis. To demonstrate the functionality of its Fc-region, the capacity of IGN311 to mediate complement dependent cytotoxicity (CDC) against human breast cancer cells was evaluated. The "classical" radioactive method using chromium-51 and a FACS-based assay were established and qualified according to ICH guidelines. Parameters evaluated were specificity, response function, bias, repeatability (intra-day precision), intermediate precision (operator-time different), and linearity (assay range). In the course of a fully nested design, a four-parameter logistic equation was identified as appropriate calibration model for both methods. For the radioactive assay, the bias ranged from -6.1% to -3.6%. The intermediate precision for future means of duplicate measurements revealed values from 12.5% to 15.9% and the total error (beta-expectation tolerance interval) of the method was found to be <40%. For the FACS-based assay, the bias ranged from -8.3% to 0.6% and the intermediate precision for future means of duplicate measurements revealed values from 4.2% to 8.0%. The total error of the method was found to be <25%. The presented data demonstrate that the FACS-based CDC is more accurate than the radioactive assay. Also, the elimination of radioactivity and the 'real-time' counting of apoptotic cells further justifies the implementation of this method which was subsequently applied for testing the influence of storage at 4 degrees C and 25 degrees C ('stability testing') on the potency of IGN311 drug product. The obtained results demonstrate that the qualified functional assay represents a stability indicating test method.
Non-Classical Congenital Adrenal Hyperplasia in Childhood
Kurtoğlu, Selim; Hatipoğlu, Nihal
2017-01-01
Congenital adrenal hyperplasia (CAH) is classified as classical CAH and non-classical CAH (NCCAH). In the classical type, the most severe form comprises both salt-wasting and simple virilizing forms. In the non-classical form, diagnosis can be more confusing because the patient may remain asymptomatic or the condition may be associated with signs of androgen excess in the postnatal period or in the later stages of life. This review paper will include information on clinical findings, symptoms, diagnostic approaches, and treatment modules of NCCAH. PMID:27354284
NASA Astrophysics Data System (ADS)
Aniello, P.; Ciaglia, F. M.; Di Cosmo, F.; Marmo, G.; Pérez-Pardo, J. M.
2016-10-01
We propose a new point of view regarding the problem of time in quantum mechanics, based on the idea of replacing the usual time operator T with a suitable real-valued function T on the space of physical states. The proper characterization of the function T relies on a particular relation with the dynamical evolution of the system rather than with the infinitesimal generator of the dynamics (Hamiltonian). We first consider the case of classical hamiltonian mechanics, where observables are functions on phase space and the tools of differential geometry can be applied. The idea is then extended to the case of the unitary evolution of pure states of finite-level quantum systems by means of the geometric formulation of quantum mechanics. It is found that T is a function on the space of pure states which is not associated with any self-adjoint operator. The link between T and the dynamical evolution is interpreted as defining a simultaneity relation for the states of the system with respect to the dynamical evolution itself. It turns out that different dynamical evolutions lead to different notions of simultaneity, i.e., the notion of simultaneity is a dynamical notion.
Grassmannization of classical models
NASA Astrophysics Data System (ADS)
Pollet, Lode; Kiselev, Mikhail N.; Prokof'ev, Nikolay V.; Svistunov, Boris V.
2016-11-01
Applying Feynman diagrammatics to non-fermionic strongly correlated models with local constraints might seem generically impossible for two separate reasons: (i) the necessity to have a Gaussian (non-interacting) limit on top of which the perturbative diagrammatic expansion is generated by Wick’s theorem, and (ii) Dyson’s collapse argument implying that the expansion in powers of coupling constant is divergent. We show that for arbitrary classical lattice models both problems can be solved/circumvented by reformulating the high-temperature expansion (more generally, any discrete representation of the model) in terms of Grassmann integrals. Discrete variables residing on either links, plaquettes, or sites of the lattice are associated with the Grassmann variables in such a way that the partition function (as well as all correlation functions) of the original system and its Grassmann-field counterpart are identical. The expansion of the latter around its Gaussian point generates Feynman diagrams. Our work paves the way for studying lattice gauge theories by treating bosonic and fermionic degrees of freedom on equal footing.
Extended symmetrical classical electrodynamics.
Fedorov, A V; Kalashnikov, E G
2008-03-01
In this paper, we discuss a modification of classical electrodynamics in which "ordinary" point charges are absent. The modified equations contain additional terms describing the induced charges and currents. The densities of the induced charges and currents depend on the vector k and the vectors of the electromagnetic field, E and B . It is shown that the vectors E and B can be defined in terms of two four-potentials and the components of k are the components of a four-tensor of the third rank. The Lagrangian of the modified electrodynamics is defined. The conditions are derived at which only one four-potential determines the behavior of the electromagnetic field. It is also shown that static modified electrodynamics can describe the electromagnetic field in the inner region of an electric monopole. In the outer region of the electric monopole the electric field is governed by the Maxwell equations. It follows from boundary conditions at the interface between the inner and outer regions of the monopole that the vector k has a discrete spectrum. The electric and magnetic fields, energy, and angular momentum of the monopole are found for different eigenvalues of k .
Classical physics and quantum loops.
Holstein, Barry R; Donoghue, John F
2004-11-12
The standard picture of the loop expansion associates a factor of variant Planck's over 2pi with each loop, suggesting that the tree diagrams are to be associated with classical physics, while loop effects are quantum mechanical in nature. We discuss counterexamples wherein classical effects arise from loop diagrams and display the relationship between the classical terms and the long range effects of massless particles.
Quantum Inflation of Classical Shapes
NASA Astrophysics Data System (ADS)
Koslowski, Tim
2017-03-01
I consider a quantum system that possesses key features of quantum shape dynamics and show that the evolution of wave-packets will become increasingly classical at late times and tend to evolve more and more like an expanding classical system. At early times however, semiclassical effects become large and lead to an exponential mismatch of the apparent scale as compared to the expected classical evolution of the scale degree of freedom. This quantum inflation of an emergent and effectively classical system, occurs naturally in the quantum shape dynamics description of the system, while it is unclear whether and how it might arise in a constrained Hamiltonian quantization.
Making Classical Conditioning Understandable through a Demonstration Technique.
ERIC Educational Resources Information Center
Gibb, Gerald D.
1983-01-01
One lemon, an assortment of other fruits and vegetables, a tennis ball, and a Galvanic Skin Response meter are needed to implement this approach to teaching about classical conditioning in introductory psychology courses. (RM)
Making Classical Conditioning Understandable through a Demonstration Technique.
ERIC Educational Resources Information Center
Gibb, Gerald D.
1983-01-01
One lemon, an assortment of other fruits and vegetables, a tennis ball, and a Galvanic Skin Response meter are needed to implement this approach to teaching about classical conditioning in introductory psychology courses. (RM)
NASA Technical Reports Server (NTRS)
2007-01-01
M51, whose name comes from being the 51st entry in Charles Messier's catalog, is considered to be one of the classic examples of a spiral galaxy. At a distance of about 30 million light-years from Earth, it is also one of the brightest spirals in the night sky. A composite image of M51, also known as the Whirlpool Galaxy, shows the majesty of its structure in a dramatic new way through several of NASA's orbiting observatories. X-ray data from NASA's Chandra X-ray Observatory reveals point-like sources (purple) that are black holes and neutron stars in binary star systems. Chandra also detects a diffuse glow of hot gas that permeates the space between the stars. Optical data from the Hubble Space Telescope (green) and infrared emission from the Spitzer Space Telescope (red) both highlight long lanes in the spiral arms that consist of stars and gas laced with dust. A view of M51 with the Galaxy Evolution Explorer telescope shows hot, young stars that produce lots of ultraviolet energy (blue).
The textbook spiral structure is thought be the result of an interaction M51 is experiencing with its close galactic neighbor, NGC 5195, which is seen just above. Some simulations suggest M51's sharp spiral shape was partially caused when NGC 5195 passed through its main disk about 500 million years ago. This gravitational tug of war may also have triggered an increased level of star formation in M51. The companion galaxy's pull would be inducing extra starbirth by compressing gas, jump-starting the process by which stars form.
NASA Technical Reports Server (NTRS)
2007-01-01
M51, whose name comes from being the 51st entry in Charles Messier's catalog, is considered to be one of the classic examples of a spiral galaxy. At a distance of about 30 million light-years from Earth, it is also one of the brightest spirals in the night sky. A composite image of M51, also known as the Whirlpool Galaxy, shows the majesty of its structure in a dramatic new way through several of NASA's orbiting observatories. X-ray data from NASA's Chandra X-ray Observatory reveals point-like sources (purple) that are black holes and neutron stars in binary star systems. Chandra also detects a diffuse glow of hot gas that permeates the space between the stars. Optical data from the Hubble Space Telescope (green) and infrared emission from the Spitzer Space Telescope (red) both highlight long lanes in the spiral arms that consist of stars and gas laced with dust. A view of M51 with the Galaxy Evolution Explorer telescope shows hot, young stars that produce lots of ultraviolet energy (blue).
The textbook spiral structure is thought be the result of an interaction M51 is experiencing with its close galactic neighbor, NGC 5195, which is seen just above. Some simulations suggest M51's sharp spiral shape was partially caused when NGC 5195 passed through its main disk about 500 million years ago. This gravitational tug of war may also have triggered an increased level of star formation in M51. The companion galaxy's pull would be inducing extra starbirth by compressing gas, jump-starting the process by which stars form.
Semi-classical methods in nuclear physics
NASA Astrophysics Data System (ADS)
Brink, David M.
These lecture notes present an introduction to some semi-classical techniques which have applications in nuclear physics. Topics discussed include the WKB method, approaches based on the Feynman path integral, the Gutzwiller trace formula for level density fluctuations and the Thomas-Fermi approximation and the Vlasov equation for many-body problems. There are applications to heavy ion fusion reactions, bremsstrahlung emission in alpha decay and nuclear response functions.
Pembrolizumab in classical Hodgkin's lymphoma.
Maly, Joseph; Alinari, Lapo
2016-09-01
Pembrolizumab is a humanized monoclonal antibody directed against programmed cell death protein 1 (PD-1), a key immune-inhibitory molecule expressed on T cells and implicated in CD4+ T-cell exhaustion and tumor immune-escape mechanisms. Classical Hodgkin's lymphoma (cHL) is a unique B-cell malignancy in the sense that malignant Reed-Sternberg (RS) cells represent a small percentage of cells within an extensive immune cell infiltrate. PD-1 ligands are upregulated on RS cells as a consequence of both chromosome 9p24.1 amplification and Epstein-Barr virus infection and by interacting with PD-1 promote an immune-suppressive effect. By augmenting antitumor immune response, pembrolizumab and nivolumab, another monoclonal antibody against PD-1, have shown significant activity in patients with relapsed/refractory cHL as well as an acceptable toxicity profile with immune-related adverse events that are generally manageable. In this review, we explore the rationale for targeting PD-1 in cHL, review the clinical trial results supporting the use of checkpoint inhibitors in this disease, and present future directions for investigation in which this approach may be used.
Dynamical Symmetries in Classical Mechanics
ERIC Educational Resources Information Center
Boozer, A. D.
2012-01-01
We show how symmetries of a classical dynamical system can be described in terms of operators that act on the state space for the system. We illustrate our results by considering a number of possible symmetries that a classical dynamical system might have, and for each symmetry we give examples of dynamical systems that do and do not possess that…
Teaching and Demonstrating Classical Conditioning.
ERIC Educational Resources Information Center
Sparrow, John; Fernald, Peter
1989-01-01
Discusses classroom demonstrations of classical conditioning and notes tendencies to misrepresent Pavlov's procedures. Describes the design and construction of the conditioner that is used for demonstrating classical conditioning. Relates how students experience conditioning, generalization, extinction, discrimination, and spontaneous recovery.…
Dynamical Symmetries in Classical Mechanics
ERIC Educational Resources Information Center
Boozer, A. D.
2012-01-01
We show how symmetries of a classical dynamical system can be described in terms of operators that act on the state space for the system. We illustrate our results by considering a number of possible symmetries that a classical dynamical system might have, and for each symmetry we give examples of dynamical systems that do and do not possess that…
Operator Formulation of Classical Mechanics.
ERIC Educational Resources Information Center
Cohn, Jack
1980-01-01
Discusses the construction of an operator formulation of classical mechanics which is directly concerned with wave packets in configuration space and is more similar to that of convential quantum theory than other extant operator formulations of classical mechanics. (Author/HM)
Teaching and Demonstrating Classical Conditioning.
ERIC Educational Resources Information Center
Sparrow, John; Fernald, Peter
1989-01-01
Discusses classroom demonstrations of classical conditioning and notes tendencies to misrepresent Pavlov's procedures. Describes the design and construction of the conditioner that is used for demonstrating classical conditioning. Relates how students experience conditioning, generalization, extinction, discrimination, and spontaneous recovery.…
Operator Formulation of Classical Mechanics.
ERIC Educational Resources Information Center
Cohn, Jack
1980-01-01
Discusses the construction of an operator formulation of classical mechanics which is directly concerned with wave packets in configuration space and is more similar to that of convential quantum theory than other extant operator formulations of classical mechanics. (Author/HM)
Fertility preservation in female classic galactosemia patients
2013-01-01
Almost every female classic galactosemia patient develops primary ovarian insufficiency (POI) as a diet-independent complication of the disease. This is a major concern for patients and their parents, and physicians are often asked about possible options to preserve fertility. Unfortunately, there are no recommendations on fertility preservation in this group. The unique pathophysiology of classic galactosemia with a severely reduced follicle pool at an early age requires an adjusted approach. In this article recommendations for physicians based on current knowledge concerning galactosemia and fertility preservation are made. Fertility preservation is only likely to be successful in very young prepubertal patients. In this group, cryopreservation of ovarian tissue is currently the only available technique. However, this technique is not ready for clinical application, it is considered experimental and reduces the ovarian reserve. Fertility preservation at an early age also raises ethical questions that should be taken into account. In addition, spontaneous conception despite POI is well described in classic galactosemia. The uncertainty surrounding fertility preservation and the significant chance of spontaneous pregnancy warrant counseling towards conservative application of these techniques. We propose that fertility preservation should only be offered with appropriate institutional research ethics approval to classic galactosemia girls at a young prepubertal age. PMID:23866841
Fertility preservation in female classic galactosemia patients.
van Erven, Britt; Gubbels, Cynthia S; van Golde, Ron J; Dunselman, Gerard A; Derhaag, Josien G; de Wert, Guido; Geraedts, Joep P; Bosch, Annet M; Treacy, Eileen P; Welt, Corrine K; Berry, Gerard T; Rubio-Gozalbo, M Estela
2013-07-16
Almost every female classic galactosemia patient develops primary ovarian insufficiency (POI) as a diet-independent complication of the disease. This is a major concern for patients and their parents, and physicians are often asked about possible options to preserve fertility. Unfortunately, there are no recommendations on fertility preservation in this group. The unique pathophysiology of classic galactosemia with a severely reduced follicle pool at an early age requires an adjusted approach. In this article recommendations for physicians based on current knowledge concerning galactosemia and fertility preservation are made. Fertility preservation is only likely to be successful in very young prepubertal patients. In this group, cryopreservation of ovarian tissue is currently the only available technique. However, this technique is not ready for clinical application, it is considered experimental and reduces the ovarian reserve. Fertility preservation at an early age also raises ethical questions that should be taken into account. In addition, spontaneous conception despite POI is well described in classic galactosemia. The uncertainty surrounding fertility preservation and the significant chance of spontaneous pregnancy warrant counseling towards conservative application of these techniques. We propose that fertility preservation should only be offered with appropriate institutional research ethics approval to classic galactosemia girls at a young prepubertal age.
[Sequencing - classical method].
Sedivcová, Monika; Martínek, Petr; Stehlík, Jan; Grossmann, Petr; Kašpírková, Jana; Vaneček, Tomáš
2013-06-01
In this article the basic methods of reading nucleotide sequences in DNA molecules are summarized. Sanger sequencing is described most thoroughly as it is the most frequent routine method currently being utilized. The article describes in detail the principle of sequence determination through the production of fragments with a known end base using chain termination synthesis of DNA and ways of separation and detection of the fragments. Some alternative methods of sequencing are mentioned in short. Basic approaches of analyzing sequence data are explained as well as different outcomes, obstacles and challenges.
On quantum vs. classical probability
Rau, Jochen
2009-12-15
Quantum theory shares with classical probability theory many important properties. I show that this common core regards at least the following six areas, and I provide details on each of these: the logic of propositions, symmetry, probabilities, composition of systems, state preparation and reductionism. The essential distinction between classical and quantum theory, on the other hand, is shown to be joint decidability versus smoothness; for the latter in particular I supply ample explanation and motivation. Finally, I argue that beyond quantum theory there are no other generalisations of classical probability theory that are relevant to physics.
Quantum localization of classical mechanics
NASA Astrophysics Data System (ADS)
Batalin, Igor A.; Lavrov, Peter M.
2016-07-01
Quantum localization of classical mechanics within the BRST-BFV and BV (or field-antifield) quantization methods are studied. It is shown that a special choice of gauge fixing functions (or BRST-BFV charge) together with the unitary limit leads to Hamiltonian localization in the path integral of the BRST-BFV formalism. In turn, we find that a special choice of gauge fixing functions being proportional to extremals of an initial non-degenerate classical action together with a very special solution of the classical master equation result in Lagrangian localization in the partition function of the BV formalism.
Quantum reduplication of classical solitons
NASA Astrophysics Data System (ADS)
Sveshnikov, Konstantin
1993-09-01
The possible existence of a series of quantum copies of classical soliton solutions is discussed, which do not exist when the effective Planck constant of the theory γ tends to zero. Within the conventional weak-coupling expansion in √ γ such non-classical solitons are O(√ γ) in energy and therefore lie in between the true classical solutions and elementary quantum excitations. Analytic results concerning the shape functions, masses and characteristic scales of such quantum excitations are given for soliton models of a self-interacting scalar field. Stability properties and quantization of fluctuations in the neighborhood of these configurations are also discussed in detail.
From Classical to Quantum Mechanics
NASA Astrophysics Data System (ADS)
Esposito, Giampiero; Marmo, Giuseppe; Sudarshan, George
2010-06-01
Preface; Acknowledgements; Part I. From Classical to Wave Mechanics: 1. Experimental foundations of quantum theory; 2. Classical dynamics; 3. Wave equations; 4. Wave mechanics; 5. Applications of wave mechanics; 6. Introduction to spin; 7. Perturbation theory; 8. Scattering theory; Part II. Weyl Quantization and Algebraic Methods: 9. Weyl quantization; 10. Harmonic oscillators and quantum optics; 11. Angular momentum operators; 12. Algebraic methods for eigenvalue problems; 13. From density matrix to geometric phases; Part III. Selected Topics: 14. From classical to quantum statistical mechanics; 15. Lagrangian and phase-space formulations; 16. Dirac equation and no-interaction theorem; References; Index.
From Classical to Quantum Mechanics
NASA Astrophysics Data System (ADS)
Esposito, Giampiero; Marmo, Giuseppe; Sudarshan, George
2004-03-01
Preface; Acknowledgements; Part I. From Classical to Wave Mechanics: 1. Experimental foundations of quantum theory; 2. Classical dynamics; 3. Wave equations; 4. Wave mechanics; 5. Applications of wave mechanics; 6. Introduction to spin; 7. Perturbation theory; 8. Scattering theory; Part II. Weyl Quantization and Algebraic Methods: 9. Weyl quantization; 10. Harmonic oscillators and quantum optics; 11. Angular momentum operators; 12. Algebraic methods for eigenvalue problems; 13. From density matrix to geometric phases; Part III. Selected Topics: 14. From classical to quantum statistical mechanics; 15. Lagrangian and phase-space formulations; 16. Dirac equation and no-interaction theorem; References; Index.
Classical and quantum Malus laws
NASA Astrophysics Data System (ADS)
Wódkiewicz, Krzysztof
1995-04-01
The classical and the quantum Malus laws for light and spin are discussed. It is shown that for spin 1/2, the quantum Malus law is equivalent in form to the classical Malus law provided the statistical average involves a quasidistribution function that can become negative. A generalization of Malus's law for arbitrary spin s is obtained in the form of a Feynman path-integral representation for the Malus amplitude. The classical limit of the Malus amplitude for s-->∞ is discussed.
Classical Hamiltonian structures in wave packet dynamics
NASA Astrophysics Data System (ADS)
Gray, Stephen K.; Verosky, John M.
1994-04-01
The general, N state matrix representation of the time-dependent Schrödinger equation is equivalent to an N degree of freedom classical Hamiltonian system. We describe how classical mechanical methods and ideas can be applied towards understanding and modeling exact quantum dynamics. Two applications are presented. First, we illustrate how qualitative insights may be gained by treating the two state problem with a time-dependent coupling. In the case of periodic coupling, Poincaré surfaces of section are used to view the quantum dynamics, and features such as the Floquet modes take on interesting interpretations. The second application illustrates computational implications by showing how Liouville's theorem, or more generally the symplectic nature of classical Hamiltonian dynamics, provides a new perspective for carrying out numerical wave packet propagation. We show how certain simple and explicit symplectic integrators can be used to numerically propagate wave packets. The approach is illustrated with an application to the problem of a diatomic molecule interacting with a laser, although it and related approaches may be useful for describing a variety of problems.
Classical and quantum-mechanical state reconstruction
NASA Astrophysics Data System (ADS)
Khanna, F. C.; Mello, P. A.; Revzen, M.
2012-07-01
The aim of this paper is to present the subject of state reconstruction in classical and in quantum physics, a subject that deals with the experimentally acquired information that allows the determination of the physical state of a system. Our first purpose is to explain a method for retrieving a classical state in phase space, similar to that used in medical imaging known as computer-aided tomography. It is remarkable that this method can be taken over to quantum mechanics, where it leads to a description of the quantum state in terms of the Wigner function which, although it may take on negative values, plays the role of the probability density in phase space in classical physics. We then present another approach to quantum state reconstruction based on the notion of mutually unbiased bases—a notion of current research interest, for which we give explanatory remarks—and indicate the relation between these two approaches. Since the subject of state reconstruction is rarely considered at the level of textbooks, the presentation in this paper is aimed at graduate-level readers.
Quantum and classical dissipation of charged particles
Ibarra-Sierra, V.G.; Anzaldo-Meneses, A.; Cardoso, J.L.; Hernández-Saldaña, H.; Kunold, A.; Roa-Neri, J.A.E.
2013-08-15
A Hamiltonian approach is presented to study the two dimensional motion of damped electric charges in time dependent electromagnetic fields. The classical and the corresponding quantum mechanical problems are solved for particular cases using canonical transformations applied to Hamiltonians for a particle with variable mass. Green’s function is constructed and, from it, the motion of a Gaussian wave packet is studied in detail. -- Highlights: •Hamiltonian of a damped charged particle in time dependent electromagnetic fields. •Exact Green’s function of a charged particle in time dependent electromagnetic fields. •Time evolution of a Gaussian wave packet of a damped charged particle. •Classical and quantum dynamics of a damped electric charge.
Experimental contextuality in classical light
NASA Astrophysics Data System (ADS)
Li, Tao; Zeng, Qiang; Song, Xinbing; Zhang, Xiangdong
2017-03-01
The Klyachko, Can, Binicioglu, and Shumovsky (KCBS) inequality is an important contextuality inequality in three-level system, which has been demonstrated experimentally by using quantum states. Using the path and polarization degrees of freedom of classical optics fields, we have constructed the classical trit (cetrit), tested the KCBS inequality and its geometrical form (Wright’s inequality) in this work. The projection measurement has been implemented, the clear violations of the KCBS inequality and its geometrical form have been observed. This means that the contextuality inequality, which is commonly used in test of the conflict between quantum theory and noncontextual realism, may be used as a quantitative tool in classical optical coherence to describe correlation characteristics of the classical fields.
Classical Foundations: Leah Rochel Johnson
ERIC Educational Resources Information Center
Lum, Lydia
2005-01-01
This article discusses the accomplishments of Leah Rochel Johnson, Assistant Professor of Classics and Ancient Mediterranean Studies and History, Pennsylvania State University. It provides insight into her values and beliefs and testimony from those who work most closely with her.
Experimental contextuality in classical light.
Li, Tao; Zeng, Qiang; Song, Xinbing; Zhang, Xiangdong
2017-03-14
The Klyachko, Can, Binicioglu, and Shumovsky (KCBS) inequality is an important contextuality inequality in three-level system, which has been demonstrated experimentally by using quantum states. Using the path and polarization degrees of freedom of classical optics fields, we have constructed the classical trit (cetrit), tested the KCBS inequality and its geometrical form (Wright's inequality) in this work. The projection measurement has been implemented, the clear violations of the KCBS inequality and its geometrical form have been observed. This means that the contextuality inequality, which is commonly used in test of the conflict between quantum theory and noncontextual realism, may be used as a quantitative tool in classical optical coherence to describe correlation characteristics of the classical fields.
Experimental contextuality in classical light
Li, Tao; Zeng, Qiang; Song, Xinbing; Zhang, Xiangdong
2017-01-01
The Klyachko, Can, Binicioglu, and Shumovsky (KCBS) inequality is an important contextuality inequality in three-level system, which has been demonstrated experimentally by using quantum states. Using the path and polarization degrees of freedom of classical optics fields, we have constructed the classical trit (cetrit), tested the KCBS inequality and its geometrical form (Wright’s inequality) in this work. The projection measurement has been implemented, the clear violations of the KCBS inequality and its geometrical form have been observed. This means that the contextuality inequality, which is commonly used in test of the conflict between quantum theory and noncontextual realism, may be used as a quantitative tool in classical optical coherence to describe correlation characteristics of the classical fields. PMID:28291227
Quantum money with classical verification
NASA Astrophysics Data System (ADS)
Gavinsky, Dmitry
2014-12-01
We propose and construct a quantum money scheme that allows verification through classical communication with a bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification. Our scheme is secure against adaptive adversaries - this property is not directly related to the possibility of classical verification, nevertheless none of the earlier quantum money constructions is known to possess it.
Classical theory of radiating strings
NASA Technical Reports Server (NTRS)
Copeland, Edmund J.; Haws, D.; Hindmarsh, M.
1990-01-01
The divergent part of the self force of a radiating string coupled to gravity, an antisymmetric tensor and a dilaton in four dimensions are calculated to first order in classical perturbation theory. While this divergence can be absorbed into a renormalization of the string tension, demanding that both it and the divergence in the energy momentum tensor vanish forces the string to have the couplings of compactified N = 1 D = 10 supergravity. In effect, supersymmetry cures the classical infinities.
Quantum money with classical verification
Gavinsky, Dmitry
2014-12-04
We propose and construct a quantum money scheme that allows verification through classical communication with a bank. This is the first demonstration that a secure quantum money scheme exists that does not require quantum communication for coin verification. Our scheme is secure against adaptive adversaries - this property is not directly related to the possibility of classical verification, nevertheless none of the earlier quantum money constructions is known to possess it.
Planck's radiation law: is a quantum-classical perspective possible?
NASA Astrophysics Data System (ADS)
Marrocco, Michele
2016-05-01
Planck's radiation law provides the solution to the blackbody problem that marks the decline of classical physics and the rise of the quantum theory of the radiation field. Here, we venture to suggest the possibility that classical physics might be equally suitable to deal with the blackbody problem. A classical version of the Planck's radiation law seems to be achievable if we learn from the quantum-classical correspondence between classical Mie theory and quantum-mechanical wave scattering from spherical scatterers (partial wave analysis). This correspondence designs a procedure for countable energy levels of the radiation trapped within the blackbody treated within the multipole approach of classical electrodynamics (in place of the customary and problematic expansion in terms of plane waves that give rise to the ultraviolet catastrophe). In turn, introducing the Boltzmann discretization of energy levels, the tools of classical thermodynamics and statistical theory become available for the task. On the other hand, the final result depends on a free parameter whose physical units are those of an action. Tuning this parameter on the value given by the Planck constant makes the classical result agree with the canonical Planck's radiation law.
Universal local symmetries and nonsuperposition in classical mechanics.
Gozzi, Ennio; Pagani, Carlo
2010-10-08
In the Hilbert space formulation of classical mechanics, pioneered by Koopman and von Neumann, there are potentially more observables than in the standard approach to classical mechanics. In this Letter, we show that actually many of those extra observables are not invariant under a set of universal local symmetries which appear once the Koopman and von Neumann formulation is extended to include the evolution of differential forms. Because of their noninvariance, those extra observables have to be removed. This removal makes the superposition of states in the Koopman and von Neumann formulation, and as a consequence also in classical mechanics, impossible.
Meissner effect, diamagnetism, and classical physics--a review
NASA Astrophysics Data System (ADS)
Essén, Hanno; Fiolhais, Miguel C. N.
2012-02-01
We review the literature on what classical physics says about the Meissner effect and the London equations. We discuss the relevance of the Bohr-van Leeuwen theorem for the perfect diamagnetism of superconductors and conclude that the theorem is based on invalid assumptions. We also point out results in the literature that show how magnetic flux expulsion from a sample cooled to superconductivity can be understood as an approach to the magnetostatic energy minimum. These results have been published several times but many textbooks on magnetism still claim that there is no classical diamagnetism, and virtually all books on superconductivity repeat Meissner's 1933 statement that flux expulsion has no classical explanation.
Classical Coding and the Cauchy-Schwarz Inequality
NASA Astrophysics Data System (ADS)
Janssens, Bas
2008-08-01
In classical coding, a single quantum state is encoded into classical information. Decoding this classical information in order to regain the original quantum state is known to be impossible. However, one can attempt to construct a state which comes as close as possible. We give bounds on the smallest possible trace distance between the original and the decoded state which can be reached. We give two approaches to the problem: one starting from Keyl and Werner's no-cloning theorem3, and one starting from an operator-valued Cauchy-Schwarz inequality.
NASA Astrophysics Data System (ADS)
Khrennikov, Andrei
2011-03-01
The idea that quantum randomness can be reduced to randomness of classical fields (fluctuating at time and space scales which are essentially finer than scales approachable in modern quantum experiments) is rather old. Various models have been proposed, e.g., stochastic electrodynamics or the semiclassical model. Recently a new model, so called prequantum classical statistical field theory (PCSFT), was developed. By this model a "quantum system" is just a label for (so to say "prequantum") classical random field. Quantum averages can be represented as classical field averages. Correlations between observables on subsystems of a composite system can be as well represented as classical correlations. In particular, it can be done for entangled systems. Creation of such classical field representation demystifies quantum entanglement. In this paper we show that quantum dynamics (given by Schrödinger's equation) of entangled systems can be represented as the stochastic dynamics of classical random fields. The "effect of entanglement" is produced by classical correlations which were present at the initial moment of time, cf. views of Albert Einstein.
Fundamental frequency from classical molecular dynamics.
Yamada, Tomonori; Aida, Misako
2015-02-07
We give a theoretical validation for calculating fundamental frequencies of a molecule from classical molecular dynamics (MD) when its anharmonicity is small enough to be treated by perturbation theory. We specifically give concrete answers to the following questions: (1) What is the appropriate initial condition of classical MD to calculate the fundamental frequency? (2) From that condition, how accurately can we extract fundamental frequencies of a molecule? (3) What is the benefit of using ab initio MD for frequency calculations? Our analytical approaches to those questions are classical and quantum normal form theories. As numerical examples we perform two types of MD to calculate fundamental frequencies of H2O with MP2/aug-cc-pVTZ: one is based on the quartic force field and the other one is direct ab initio MD, where the potential energies and the gradients are calculated on the fly. From those calculations, we show comparisons of the frequencies from MD with the post vibrational self-consistent field calculations, second- and fourth-order perturbation theories, and experiments. We also apply direct ab initio MD to frequency calculations of C-H vibrational modes of tetracene and naphthalene. We conclude that MD can give the same accuracy in fundamental frequency calculation as second-order perturbation theory but the computational cost is lower for large molecules.
CLASSSTRONG: Classical simulations of strong field processes
NASA Astrophysics Data System (ADS)
Ciappina, M. F.; Pérez-Hernández, J. A.; Lewenstein, M.
2014-01-01
A set of Mathematica functions is presented to model classically two of the most important processes in strong field physics, namely high-order harmonic generation (HHG) and above-threshold ionization (ATI). Our approach is based on the numerical solution of the Newton-Lorentz equation of an electron moving on an electric field and takes advantage of the symbolic languages features and graphical power of Mathematica. Like in the Strong Field Approximation (SFA), the effects of atomic potential on the motion of electron in the laser field are neglected. The SFA was proven to be an essential tool in strong field physics in the sense that it is able to predict with great precision the harmonic (in the HHG) and energy (in the ATI) limits. We have extended substantially the conventional classical simulations, where the electric field is only dependent on time, including spatial nonhomogeneous fields and spatial and temporal synthesized fields. Spatial nonhomogeneous fields appear when metal nanosystems interact with strong and short laser pulses and temporal synthesized fields are routinely generated in attosecond laboratories around the world. Temporal and spatial synthesized fields have received special attention nowadays because they would allow to exceed considerably the conventional harmonic and electron energy frontiers. Classical simulations are an invaluable tool to explore exhaustively the parameters domain at a cheap computational cost, before massive quantum mechanical calculations, absolutely indispensable for the detailed analysis, are performed.
NASA Astrophysics Data System (ADS)
Lacquaniti, Francesco; Ivanenko, Yuri P.; Zago, Myrka
2016-07-01
Starting from the classical concepts introduced by Sherrington [1] and considerably elaborated by Bernstein [2], much has been learned about motor synergies in the last several years. The contributions of the group funded by the European project ;The Hand Embodied; are remarkable in the field of biological and robotic control of the hand based on synergies, and they are reflected in this enjoyable review [3]. There, Santello et al. adopt Bernstein's definition of motor synergies as multiple elements working together towards a common goal, with the result that multiple degrees of freedom are controlled within a lower-dimensional space than the available number of dimensions.
Classical problems in computational aero-acoustics
NASA Technical Reports Server (NTRS)
Hardin, Jay C.
1996-01-01
In relation to the expected problems in the development of computational aeroacoustics (CAA), the preliminary applications were to classical problems where the known analytical solutions could be used to validate the numerical results. Such comparisons were used to overcome the numerical problems inherent in these calculations. Comparisons were made between the various numerical approaches to the problems such as direct simulations, acoustic analogies and acoustic/viscous splitting techniques. The aim was to demonstrate the applicability of CAA as a tool in the same class as computational fluid dynamics. The scattering problems that occur are considered and simple sources are discussed.
Soliton splitting in quenched classical integrable systems
NASA Astrophysics Data System (ADS)
Gamayun, O.; Semenyakin, M.
2016-08-01
We take a soliton solution of a classical non-linear integrable equation and quench (suddenly change) its non-linearity parameter. For that we multiply the amplitude or the width of a soliton by a numerical factor η and take the obtained profile as a new initial condition. We find the values of η for which the post-quench solution consists of only a finite number of solitons. The parameters of these solitons are found explicitly. Our approach is based on solving the direct scattering problem analytically. We demonstrate how it works for Korteweg-de Vries, sine-Gordon and non-linear Schrödinger integrable equations.
Quantum remnants in the classical limit
NASA Astrophysics Data System (ADS)
Kowalski, A. M.; Plastino, A.
2016-09-01
We analyze here the common features of two dynamical regimes: a quantum and a classical one. We deal with a well known semi-classic system in its route towards the classical limit, together with its purely classic counterpart. We wish to ascertain i) whether some quantum remnants can be found in the classical limit and ii) the details of the quantum-classic transition. The so-called mutual information is the appropriate quantifier for this task. Additionally, we study the Bandt-Pompe's symbolic patterns that characterize dynamical time series (representative of the semi-classical system under scrutiny) in their evolution towards the classical limit.
Entropy concepts in classical electrodynamics
NASA Astrophysics Data System (ADS)
Cole, Daniel C.
2002-11-01
Aspects of entropy and related thermodynamic analyses are discussed here that have been deduced in recent years in the area of classical electrodynamics. A motivating factor for most of this work has been an attempted theory of nature often called, "stochastic electrodynamics" (SED). This theory involves classical electrodynamics (Maxwell's equations plus the relativistic version of Newton's second law of motion for particles), but with the consideration that motion and fluctuations should not necessarily be assumed to reduce to zero at temperature T = 0. Both fairly subtle and rather blatant assumptions were often imposed in early thermodynamic analyses of electrodynamic systems that prevented the analyses from being sufficiently general to account for these "zero-point" properties, which hindered classical physics from being able to better account for quantum mechanical phenomena observed in nature. In turn, such thermodynamic considerations have helped motivate many of the key ideas of SED.
Classical anomalies for spinning particles
NASA Astrophysics Data System (ADS)
Gamboa, Jorge; Plyushchay, Mikhail
1998-02-01
We discuss the phenomenon of classical anomaly. It is observed for 3D Berezin-Marinov (BM), Barducci-Casalbuoni-Lusanna (BCL) and Cortés-Plyushchay-Velázquez (CPV) pseudoclassical spin particle models. We show that quantum mechanically these different models correspond to the same P, T-invariant system of planar fermions, but the quantum system has global symmetries being not reproducible classically in full in any of the models. We demonstrate that the specific U(1) gauge symmetry characterized by the opposite coupling constants of spin s = + {1}/{2} and s = - {1}/{2} states has a natural classical analog in the CPV model but can be reproduced in the BM and BCL models in an obscure and rather artificial form. We also show that the BM and BCL models quantum mechanically are equivalent in any odd-dimensional space-time, but describe different quantum systems in even space-time dimensions.
From classical to quantum criticality
NASA Astrophysics Data System (ADS)
Podolsky, Daniel; Shimshoni, Efrat; Silvi, Pietro; Montangero, Simone; Calarco, Tommaso; Morigi, Giovanna; Fishman, Shmuel
2014-06-01
We study the crossover from classical to quantum phase transitions at zero temperature within the framework of ϕ4 theory. The classical transition at zero temperature can be described by the Landau theory, turning into a quantum Ising transition with the addition of quantum fluctuations. We perform a calculation of the transition line in the regime where the quantum fluctuations are weak. The calculation is based on a renormalization group analysis of the crossover between classical and quantum transitions, and is well controlled even for space-time dimensionality D below 4. In particular, for D =2 we obtain an analytic expression for the transition line which is valid for a wide range of parameters, as confirmed by numerical calculations based on the density matrix renormalization group. This behavior could be tested by measuring the phase diagram of the linear-zigzag instability in systems of trapped ions or repulsively interacting dipoles.
Overview of Classical Swine Fever (Hog Cholera, Classical Swine fever)
USDA-ARS?s Scientific Manuscript database
Classical swine fever is a contagious often fatal disease of pigs clinically characterized by high body temperature, lethargy, yellowish diarrhea, vomits and purple skin discoloration of ears, lower abdomen and legs. It was first described in the early 19th century in the USA. Later, a condition i...
Optimum Onager: The Classical Mechanics of a Classical Siege Engine
ERIC Educational Resources Information Center
Denny, Mark
2009-01-01
The onager is a throwing weapon of classical antiquity, familiar to both the ancient Greeks and Romans. Here we analyze the dynamics of onager operation and derive the optimum angle for launching a projectile to its maximum range. There is plenty of scope for further considerations about increasing onager range, and so by thinking about how this…
Optimum Onager: The Classical Mechanics of a Classical Siege Engine
ERIC Educational Resources Information Center
Denny, Mark
2009-01-01
The onager is a throwing weapon of classical antiquity, familiar to both the ancient Greeks and Romans. Here we analyze the dynamics of onager operation and derive the optimum angle for launching a projectile to its maximum range. There is plenty of scope for further considerations about increasing onager range, and so by thinking about how this…
Therapeutic Applications of Classic Hallucinogens.
Bogenschutz, Michael P; Ross, Stephen
2017-05-18
This chapter reviews what is known about the therapeutic uses of the serotonergic or classic hallucinogens, i.e., psychoactive drugs such as LSD and psilocybin that exert their effects primarily through agonist activity at serotonin 2A (5HT2A) receptors. Following a review of the history of human use and scientific study of these drugs, the data from clinical research are summarized, including extensive work on the use of classic hallucinogens in the treatment of alcoholism and other addictions, studies of the use of LSD and psilocybin to relieve distress concerning death, particularly in patients with advanced or terminal cancer, and more limited data concerning the use of classic hallucinogens to treat mood and anxiety disorders. A survey of possible mechanisms of clinically relevant effects is provided. The well-established safety of classic hallucinogens is reviewed. To provide a clinical perspective, case summaries are provided of two individuals who received treatment in recent controlled trials of psilocybin: one being treated for alcoholism, the other suffering from anxiety and depression related to fear of death due to a cancer diagnosis. Although promising early phase research conducted from the 1950s through the early 1970s was discontinued before firm conclusions could be reached concerning the efficacy of any of the classic hallucinogens for any clinical condition, the research that was conducted in that era strongly suggests that classic hallucinogens have clinically relevant effects, particularly in the case of LSD treatment of alcoholism. In the past decade, clinical trials have resumed investigating the effects of classic hallucinogens in the treatment of existential distress in the face of cancer, and in the treatment of addictions including alcoholism and nicotine addiction. The studies that have been completed to date are not sufficient to establish efficacy, but the outcomes have been very encouraging, and larger trials, up to and including
Quantum teleportation without classical channel
NASA Astrophysics Data System (ADS)
Al Amri, M.; Li, Zheng-Hong; Zubairy, M. Suhail
2016-11-01
For the first time, we show how quantum teleportation can be achieved without the assistance of classical channels. Our protocol does not need any pre-established entangled photon pairs beforehand. Just by utilizing quantum Zeno effect and couterfactual communication idea, we can achieve two goals; entangling a photon and an atom and also disentangling them by non-local interaction. Information is completely transferred from atom to photon with controllable disentanglement processes. More importantly, there is no need to confirm teleportation results via classical channels.
Classical picture of postexponential decay
Torrontegui, E.; Muga, J. G.; Martorell, J.; Sprung, D. W. L.
2010-04-15
Postexponential decay of the probability density of a quantum particle leaving a trap can be reproduced accurately, except for interference oscillations at the transition to the postexponential regime, by means of an ensemble of classical particles emitted with constant probability per unit time and the same half-life as the quantum system. The energy distribution of the ensemble is chosen to be identical to the quantum distribution, and the classical point source is located at the scattering length of the corresponding quantum system. A one-dimensional example is provided to illustrate the general argument.
NASA Astrophysics Data System (ADS)
Kirkpatrick, K. A.
2003-05-01
A simple classical probabilistic system (a simple card game) classically exemplifies Aharonov and Vaidman's 'three-box 'paradox'' (1991 J. Phys. A: Math. Gen. 24 2315), implying that the three-box example is neither quantal nor a paradox and leaving one with less difficulty to busy the interpreters of quantum mechanics. An ambiguity in the usual expression of the retrodiction formula is shown to have misled Albert et al (1985 Phys. Rev. Lett. 54 5) to a result not, in fact, 'curious'; the discussion illustrates how to avoid this ambiguity.
Comparing classical and quantum equilibration
NASA Astrophysics Data System (ADS)
Malabarba, Artur S. L.; Farrelly, Terry; Short, Anthony J.
2016-09-01
By using a physically relevant and theory independent definition of measurement-based equilibration, we show quantitatively that equilibration is easier for quantum systems than for classical systems, in the situation where the initial state of the system is completely known (a pure state). This shows that quantum equilibration is a fundamental aspect of many quantum systems, while classical equilibration relies on experimental ignorance. When the state is not completely known (a mixed state), this framework also shows that quantum equilibration requires weaker conditions.
Sławuta, P; Glińska-Suchocka, K
2012-01-01
Classically, the acid-base balance (ABB) is described by the Henderson-Hasselbach equation, where the blood pH is a result of a metabolic components--the HCO3(-) concentration and a respiratory component--pCO2. The Stewart model assumes that the proper understanding of the organisms ABB is based on an analysis of: pCO2, Strong Ion difference (SID)--the difference strong cation and anion concentrations in the blood serum, and the Acid total (Atot)--the total concentration of nonvolatile weak acids. Right sided heart failure in dogs causes serious haemodynamic disorders in the form of peripheral stasis leading to formation of transudates in body cavities, which in turn causes ABB respiratory and metabolic disorders. The study was aimed at analysing the ABB parameters with the use of the classic method and the Stewart model in dogs with the right sided heart failure and a comparison of both methods for the purpose of their diagnostic and therapeutic utility. The study was conducted on 10 dogs with diagnosed right sided heart failure. Arterial and venous blood was drawn from the animals. Analysis of pH, pCO2 and HCO3(-) was performed from samples of arterial blood. Concentrations of Na+, K+, Cl(-), P(inorganic), albumins and lactate were determined from venous blood samples and values of Strong Ion difference of Na+, K+ and Cl(-) (SID3), Strong Ion difference of Na+, K+, Cl(-) and lactate (SID4), Atot, Strong Ion difference effective (SIDe) and Strong Ion Gap (SIG4) were calculated. The conclusions are as follows: 1) diagnosis of ABB disorders on the basis of the Stewart model showed metabolic alkalosis in all dogs examined, 2) in cases of circulatory system diseases, methodology based on the Stewart model should be applied for ABB disorder diagnosis, 3) if a diagnosis of ABB disorders is necessary, determination of pH, pCO2 and HCO3(-) as well as concentrations of albumins and P(inorganic) should be determined on a routine basis, 4) for ABB disorder diagnosis, the
Teaching Classical Mechanics Using Smartphones
ERIC Educational Resources Information Center
Chevrier, Joel; Madani, Laya; Ledenmat, Simon; Bsiesy, Ahmad
2013-01-01
A number of articles published in this column have dealt with topics in classical mechanics. This note describes some additional examples employing a smartphone and the new software iMecaProf. Steve Jobs presented the iPhone as "perfect for gaming." Thanks to its microsensors connected in real time to the numerical world, physics…
Relative Clauses in Classical Nahuatl
ERIC Educational Resources Information Center
Langacker, Ronald W.
1975-01-01
Jane Rosenthal's paper on relative clauses in Classical Nahuatl is discussed, and it is argued that she misses an important generalization. An alternative analysis to a class of relative pronouns and new rules for the distribution of relative pronouns are proposed. (SC)
Montaigne's Uses of Classical Learning.
ERIC Educational Resources Information Center
Hall, Michael L.
1997-01-01
M. de Montaigne's essay "On the Education of Children" (1580) demonstrates the importance of examining classical authors to test understanding and develop judgment. Montaigne's method provides a way to study cultural heritage and to use the past to examine current issues. Implications for teaching today are discussed. (SLD)
Classical Music as Enforced Utopia
ERIC Educational Resources Information Center
Leech-Wilkinson, Daniel
2016-01-01
In classical music composition, whatever thematic or harmonic conflicts may be engineered along the way, everything always turns out for the best. Similar utopian thinking underlies performance: performers see their job as faithfully carrying out their master's (the composer's) wishes. The more perfectly they represent them, the happier the…
Classical and molecular genetic mapping
USDA-ARS?s Scientific Manuscript database
A brief history of classical genetic mapping in soybean [Glycine max (L.) Merr.] is described. Detailed descriptions are given of the development of molecular genetic linkage maps based upon various types of DNA markers Like many plant and animal species, the first molecular map of soybean was bas...
Classical Music as Enforced Utopia
ERIC Educational Resources Information Center
Leech-Wilkinson, Daniel
2016-01-01
In classical music composition, whatever thematic or harmonic conflicts may be engineered along the way, everything always turns out for the best. Similar utopian thinking underlies performance: performers see their job as faithfully carrying out their master's (the composer's) wishes. The more perfectly they represent them, the happier the…
Classics in Reading: A Survey.
ERIC Educational Resources Information Center
Froese, Victor
1982-01-01
Frank Smith and Kenneth Goodman were the most frequently cited authors; Bond and Dykstra's "The Cooperative Research Program in First Grade Reading Instruction" and Chall's "Learning to Read: The Great Debate" the most frequently cited works in a survey that asked graduate faculty in reading to name "classics" in reading research. (FL)
Teaching Classical Mechanics Using Smartphones
ERIC Educational Resources Information Center
Chevrier, Joel; Madani, Laya; Ledenmat, Simon; Bsiesy, Ahmad
2013-01-01
A number of articles published in this column have dealt with topics in classical mechanics. This note describes some additional examples employing a smartphone and the new software iMecaProf. Steve Jobs presented the iPhone as "perfect for gaming." Thanks to its microsensors connected in real time to the numerical world, physics…
Relative Clauses in Classical Nahuatl
ERIC Educational Resources Information Center
Langacker, Ronald W.
1975-01-01
Jane Rosenthal's paper on relative clauses in Classical Nahuatl is discussed, and it is argued that she misses an important generalization. An alternative analysis to a class of relative pronouns and new rules for the distribution of relative pronouns are proposed. (SC)
Holographic entanglement beyond classical gravity
NASA Astrophysics Data System (ADS)
Barrella, Taylor; Dong, Xi; Hartnoll, Sean A.; Martin, Victoria L.
2013-09-01
The Rényi entropies and entanglement entropy of 1+1 CFTs with gravity duals can be computed by explicit construction of the bulk spacetimes dual to branched covers of the boundary geometry. At the classical level in the bulk this has recently been shown to reproduce the conjectured Ryu-Takayanagi formula for the holographic entanglement entropy. We study the one-loop bulk corrections to this formula. The functional determinants in the bulk geometries are given by a sum over certain words of generators of the Schottky group of the branched cover. For the case of two disjoint intervals on a line we obtain analytic answers for the one-loop entanglement entropy in an expansion in small cross-ratio. These reproduce and go beyond anticipated universal terms that are not visible classically in the bulk. We also consider the case of a single interval on a circle at finite temperature. At high temperatures we show that the one-loop contributions introduce expected finite size corrections to the entanglement entropy that are not present classically. At low temperatures, the one-loop corrections capture the mixed nature of the density matrix, also not visible classically below the Hawking-Page temperature.
Classical simulation of entangled states
NASA Astrophysics Data System (ADS)
Bharath, H. M.; Ravishankar, V.
2014-06-01
Characterization of nonclassicality or quantumness of a state is fundamental to foundations of quantum mechanics and quantum information. At the heart of the problem is the question whether there exist classical systems—howsoever complicated—that can mimic a given quantum state. Whilst this has been traditionally addressed through the violation of Bell inequality or nonseparability, we show that it is possible to go beyond them, by introducing the concept of classical simulation. Focusing on the two-qubit case, we show that, while for pure states, classical simulability is equivalent to existence of a local hidden variable (LHV) model, the conditions for simulability can be weaker for mixed states, demanding what we call only a generalized LHV description. Consequently, quantum states which defy a classical simulation—which we call exceptional—may require conditions which are more stringent than violation of Bell inequalities. We illustrate these features with a number of representative examples and discuss the underlying reasons, by employing fairly simple arguments.
Vowel intelligibility in classical singing.
Gregg, Jean Westerman; Scherer, Ronald C
2006-06-01
Vowel intelligibility during singing is an important aspect of communication during performance. The intelligibility of isolated vowels sung by Western classically trained singers has been found to be relatively low, in fact, decreasing as pitch rises, and it is lower for women than for men. The lack of contextual cues significantly deteriorates vowel intelligibility. It was postulated in this study that the reduced intelligibility of isolated sung vowels may be partly from the vowels used by the singers in their daily vocalises. More specifically, if classically trained singers sang only a few American English vowels during their vocalises, their intelligibility for American English vowels would be less than for those classically trained singers who usually vocalize on most American English vowels. In this study, there were 21 subjects (15 women, 6 men), all Western classically trained performers as well as teachers of classical singing. They sang 11 words containing 11 different American English vowels, singing on two pitches a musical fifth apart. Subjects were divided into two groups, those who normally vocalize on 4, 5, or 6 vowels, and those who sing all 11 vowels during their daily vocalises. The sung words were cropped to isolate the vowels, and listening tapes were created. Two listening groups, four singing teachers and five speech-language pathologists, were asked to identify the vowels intended by the singers. Results suggest that singing fewer vowels during daily vocalises does not decrease intelligibility compared with singing the 11 American English vowels. Also, in general, vowel intelligibility was lower with the higher pitch, and vowels sung by the women were less intelligible than those sung by the men. Identification accuracy was about the same for the singing teacher listeners and the speech-language pathologist listeners except for the lower pitch, where the singing teachers were more accurate.
No return to classical reality
NASA Astrophysics Data System (ADS)
Jennings, David; Leifer, Matthew
2016-01-01
At a fundamental level, the classical picture of the world is dead, and has been dead now for almost a century. Pinning down exactly which quantum phenomena are responsible for this has proved to be a tricky and controversial question, but a lot of progress has been made in the past few decades. We now have a range of precise statements showing that whatever the ultimate laws of nature are, they cannot be classical. In this article, we review results on the fundamental phenomena of quantum theory that cannot be understood in classical terms. We proceed by first granting quite a broad notion of classicality, describe a range of quantum phenomena (such as randomness, discreteness, the indistinguishability of states, measurement-uncertainty, measurement-disturbance, complementarity, non-commutativity, interference, the no-cloning theorem and the collapse of the wave-packet) that do fall under its liberal scope, and then finally describe some aspects of quantum physics that can never admit a classical understanding - the intrinsically quantum mechanical aspects of nature. The most famous of these is Bell's theorem, but we also review two more recent results in this area. Firstly, Hardy's theorem shows that even a finite-dimensional quantum system must contain an infinite amount of information, and secondly, the Pusey-Barrett-Rudolph theorem shows that the wave function must be an objective property of an individual quantum system. Besides being of foundational interest, results of this sort now find surprising practical applications in areas such as quantum information science and the simulation of quantum systems.
Global Galactic Distribution of Classical Novae
NASA Astrophysics Data System (ADS)
Iyudin, A. F.; Schönfelder, V.; Bennett, K.; Diehl, R.; Hermsen, W.; Lichti, G. G.; Ryan, J.
2002-11-01
Classical novae are considered to be the major source of the ISM enrichment with the isotopes of 13C, 15N, and 22Na. The latter, radioactive 22Na, that decays producing penetrating 1.275 MeV γ-ray photon, could be very useful as a probe of the galactic global distribution of novae. It is expected that the accumulation of 22Na from the frequent novae in the bulge will lead to an observable extended emission. Additionally, a 22Na detection from the single nova can be used to verify predictions of the modern thermonuclear runaway theory (TNR) applied to classical novae. To gain a better insight into this problem we have used a two-way approach. Namely: (1) - we have studied the global galactic distribution of the 1.275 MeV γ-ray line emission assuming that it is mostly originates from decay of the novae-produced 22Na; and (2) - we pursued the 22Na line emission detection from recent individual novae. The combination of both approaches makes possible to tap rather uncertain galactic novae rate by comparing observations of the individual Galactic novae with the integrated 22Na line emission from the disk and/or bulge population. The COMPTEL telescope on board the Compton Gamma-Ray Observatory (CGRO), due to its combination of imaging and spectroscopic capabilities, is suitable to address the above ideas.
2010-01-01
Background Patients-Reported Outcomes (PRO) are increasingly used in clinical and epidemiological research. Two main types of analytical strategies can be found for these data: classical test theory (CTT) based on the observed scores and models coming from Item Response Theory (IRT). However, whether IRT or CTT would be the most appropriate method to analyse PRO data remains unknown. The statistical properties of CTT and IRT, regarding power and corresponding effect sizes, were compared. Methods Two-group cross-sectional studies were simulated for the comparison of PRO data using IRT or CTT-based analysis. For IRT, different scenarios were investigated according to whether items or person parameters were assumed to be known, to a certain extent for item parameters, from good to poor precision, or unknown and therefore had to be estimated. The powers obtained with IRT or CTT were compared and parameters having the strongest impact on them were identified. Results When person parameters were assumed to be unknown and items parameters to be either known or not, the power achieved using IRT or CTT were similar and always lower than the expected power using the well-known sample size formula for normally distributed endpoints. The number of items had a substantial impact on power for both methods. Conclusion Without any missing data, IRT and CTT seem to provide comparable power. The classical sample size formula for CTT seems to be adequate under some conditions but is not appropriate for IRT. In IRT, it seems important to take account of the number of items to obtain an accurate formula. PMID:20338031
Strong Analog Classical Simulation of Coherent Quantum Dynamics
NASA Astrophysics Data System (ADS)
Wang, Dong-Sheng
2017-02-01
A strong analog classical simulation of general quantum evolution is proposed, which serves as a novel scheme in quantum computation and simulation. The scheme employs the approach of geometric quantum mechanics and quantum informational technique of quantum tomography, which applies broadly to cases of mixed states, nonunitary evolution, and infinite dimensional systems. The simulation provides an intriguing classical picture to probe quantum phenomena, namely, a coherent quantum dynamics can be viewed as a globally constrained classical Hamiltonian dynamics of a collection of coupled particles or strings. Efficiency analysis reveals a fundamental difference between the locality in real space and locality in Hilbert space, the latter enables efficient strong analog classical simulations. Examples are also studied to highlight the differences and gaps among various simulation methods. Funding support from NSERC of Canada and a research fellowship at Department of Physics and Astronomy, University of British Columbia are acknowledged
Miller, William H.; Orel, Ann E.
1981-06-01
A classical interpretation of the Dirac–Van Vleck spin version of valence bond theory is used in this research to obtain a classical model for electronic degrees of freedom within the valence bond framework. The approach is illustrated by deriving the explicit forms of the classical Hamiltonians, involving electronic and heavy particle degrees of freedom, for the H–H_{2}, F–H_{2}, and O–H_{2} systems. It is also shown how the initial conditions for both electronic and heavy particle degrees of freedom are chosen to carry out a classical trajectory simulation of collision processes. In addition, the attractive feature of this model is that it is as easily applicable to electronically nonadiabatic processes as it is to adiabatic ones.
Classical corrections in string cosmology
NASA Astrophysics Data System (ADS)
Brustein, Ram; Madden, Richard
1999-07-01
An important element in a model of non-singular string cosmology is a phase in which classical corrections saturate the growth of curvature in a deSitter-like phase with a linearly growing dilaton (an `algebraic fixed point'). As the form of the classical corrections is not well known, here we look for evidence, based on a suggested symmetry of the action, scale factor duality and on conformal field theory considerations, that they can produce this saturation. It has previously been observed that imposing scale factor duality on the O(alpha') corrections is not compatible with fixed point behavior. Here we present arguments that these problems persist to all orders in alpha'. We also present evidence for the form of a solution to the equations of motion using conformal perturbation theory, examine its implications for the form of the effective action and find novel fixed point structure.
Classical Analog to Entanglement Reversibility
NASA Astrophysics Data System (ADS)
Chitambar, Eric; Fortescue, Ben; Hsieh, Min-Hsiu
2015-08-01
In this Letter we study the problem of secrecy reversibility. This asks when two honest parties can distill secret bits from some tripartite distribution pX Y Z and transform secret bits back into pX Y Z at equal rates using local operation and public communication. This is the classical analog to the well-studied problem of reversibly concentrating and diluting entanglement in a quantum state. We identify the structure of distributions possessing reversible secrecy when one of the honest parties holds a binary distribution, and it is possible that all reversible distributions have this form. These distributions are more general than what is obtained by simply constructing a classical analog to the family of quantum states known to have reversible entanglement. An indispensable tool used in our analysis is a conditional form of the Gács-Körner common information.
Psoriasis: classical and emerging comorbidities*
de Oliveira, Maria de Fátima Santos Paim; Rocha, Bruno de Oliveira; Duarte, Gleison Vieira
2015-01-01
Psoriasis is a chronic inflammatory systemic disease. Evidence shows an association of psoriasis with arthritis, depression, inflammatory bowel disease and cardiovascular diseases. Recently, several other comorbid conditions have been proposed as related to the chronic inflammatory status of psoriasis. The understanding of these conditions and their treatments will certainly lead to better management of the disease. The present article aims to synthesize the knowledge in the literature about the classical and emerging comorbidities related to psoriasis. PMID:25672294
Invariants from classical field theory
Diaz, Rafael; Leal, Lorenzo
2008-06-15
We introduce a method that generates invariant functions from perturbative classical field theories depending on external parameters. By applying our methods to several field theories such as Abelian BF, Chern-Simons, and two-dimensional Yang-Mills theory, we obtain, respectively, the linking number for embedded submanifolds in compact varieties, the Gauss' and the second Milnor's invariant for links in S{sup 3}, and invariants under area-preserving diffeomorphisms for configurations of immersed planar curves.
Applications of classical detonation theory
Davis, W.C.
1994-09-01
Classical detonation theory is the basis for almost all calculations of explosive systems. One common type of calculation is of the detailed behavior of inert parts driven by explosive, predicting pressures, velocities, positions, densities, energies, etc as functions of time. Another common application of the theory is predicting the detonation state and expansion isentrope of a new explosive or mixtures, perhaps an explosive that has not yet been made. Both types of calculations are discussed.
Quantum to classical randomness extractors
NASA Astrophysics Data System (ADS)
Wehner, Stephanie; Berta, Mario; Fawzi, Omar
2013-03-01
The goal of randomness extraction is to distill (almost) perfect randomness from a weak source of randomness. When the source yields a classical string X, many extractor constructions are known. Yet, when considering a physical randomness source, X is itself ultimately the result of a measurement on an underlying quantum system. When characterizing the power of a source to supply randomness it is hence a natural question to ask, how much classical randomness we can extract from a quantum system. To tackle this question we here introduce the notion of quantum-to-classical randomness extractors (QC-extractors). We identify an entropic quantity that determines exactly how much randomness can be obtained. Furthermore, we provide constructions of QC-extractors based on measurements in a full set of mutually unbiased bases (MUBs), and certain single qubit measurements. As the first application, we show that any QC-extractor gives rise to entropic uncertainty relations with respect to quantum side information. Such relations were previously only known for two measurements. As the second application, we resolve the central open question in the noisy-storage model [Wehner et al., PRL 100, 220502 (2008)] by linking security to the quantum capacity of the adversary's storage device.
Optimum Onager: The Classical Mechanics of a Classical Siege Engine
NASA Astrophysics Data System (ADS)
Denny, Mark
2009-12-01
The onager is a throwing weapon of classical antiquity, familiar to both the ancient Greeks and Romans. Here we analyze the dynamics of onager operation and derive the optimum angle for launching a projectile to its maximum range. There is plenty of scope for further considerations about increasing onager range, and so by thinking about how this machine might be improved, a student can gain insight beyond the equations of motion and can test hypotheses on readily available working models. Some of these performance improvements are considered in this paper.
Embedding quantum into classical: contextualization vs conditionalization.
Dzhafarov, Ehtibar N; Kujala, Janne V
2014-01-01
We compare two approaches to embedding joint distributions of random variables recorded under different conditions (such as spins of entangled particles for different settings) into the framework of classical, Kolmogorovian probability theory. In the contextualization approach each random variable is "automatically" labeled by all conditions under which it is recorded, and the random variables across a set of mutually exclusive conditions are probabilistically coupled (imposed a joint distribution upon). Analysis of all possible probabilistic couplings for a given set of random variables allows one to characterize various relations between their separate distributions (such as Bell-type inequalities or quantum-mechanical constraints). In the conditionalization approach one considers the conditions under which the random variables are recorded as if they were values of another random variable, so that the observed distributions are interpreted as conditional ones. This approach is uninformative with respect to relations between the distributions observed under different conditions because any set of such distributions is compatible with any distribution assigned to the conditions.
The structure of the classical cosmological singularity
NASA Astrophysics Data System (ADS)
Tipler, Frank J.
The existence of an all-encompassing initial classical cosmological singularity is established: it is shown that if: (1) global hyperbolicity, (2) the timelike convergence condition, and (3) all past-directed nonspacelike geodesics start to reconverge within a compact region in the causal past of the present-day earth, then all timelike curves in the past have a finite proper time length less than a universal constant L. It is argued that an analogue of this predicted cosmological singularity should exist even when quantum effects are taken into account. In particular, in a closed Friedmann radiation-filled universe quantized via the ADM method, the R = 0 singularity still exists and influences wave packet evolution at all times. Furthermore, quantum effects can in most cases eliminate curvature singularities only by introducing singularities in the universal action; most classical closed universes have finite action if and only if they begin and end in curvature singularities. Finally, the two basic ways of studying the structure of cosmological singularities are reviewed: completion methods (e.g., the c-boundary construction), and approach methods (e.g., analyzing metric behavior in a synchronous coordinate system).
Classical and Quantum Shortcuts to Adiabaticity in a Tilted Piston.
Patra, Ayoti; Jarzynski, Christopher
2017-04-20
Adiabatic quantum state evolution can be accelerated through a variety of shortcuts to adiabaticity. In one approach, a counterdiabatic quantum Hamiltonian, ĤCD, is constructed to suppress nonadiabatic excitations. In the analogous classical problem, a counterdiabatic classical Hamiltonian, HCD, ensures that the classical action remains constant even under rapid driving. Both the quantum and classical versions of this problem have been solved for the special case of scale-invariant driving, characterized by linear expansions, contractions, or translations of the system. Here we investigate an example of a non-scale-invariant system, a tilted piston. We solve exactly for the classical counterdiabatic Hamiltonian, HCD(q, p, t), which we then quantize to obtain a Hermitian operator, ĤCD(t). Using numerical simulations, we find that ĤCD effectively suppresses nonadiabatic excitations under rapid driving. These results offer a proof of principle, beyond the special case of scale-invariant driving, that quantum shortcuts to adiabaticity can successfully be constructed from their classical counterparts.
Can fluctuations of classical random field produce quantum averages?
NASA Astrophysics Data System (ADS)
Khrennikov, Andrei
2009-08-01
Albert Einstein did not believe in completeness of QM. He dreamed of creation of prequantum classical statistical mechanics such that QM will be reproduced as its approximation. He also dreamed of total exclusion of corpuscules from the future model. Reality of Einstein's dream was pure fields' reality. Recently I made his dream come true in the form of so called prequantum classical statistical field theory (PCSFT). In this approach quantum systems are described by classical random fields, e.g., electromagnetic field (instead of photon), electron field or neutron field. In this paper we generalize PCSFT to composite quantum system. It is well known that in QM, unlike classical mechanics, the state of a composite system is described by the tensor product of state spaces for its subsystems. In PCSFT one can still use Cartesian product, but state spaces are spaces of classical fields (not particles). In particular, entanglement is nothing else than correlation of classical random fields, cf. again Einstein. Thus entanglement was finally demystified.
Classical molecular dynamics simulation of electronically non-adiabatic processes.
Miller, William H; Cotton, Stephen J
2016-12-22
Both classical and quantum mechanics (as well as hybrids thereof, i.e., semiclassical approaches) find widespread use in simulating dynamical processes in molecular systems. For large chemical systems, however, which involve potential energy surfaces (PES) of general/arbitrary form, it is usually the case that only classical molecular dynamics (MD) approaches are feasible, and their use is thus ubiquitous nowadays, at least for chemical processes involving dynamics on a single PES (i.e., within a single Born-Oppenheimer electronic state). This paper reviews recent developments in an approach which extends standard classical MD methods to the treatment of electronically non-adiabatic processes, i.e., those that involve transitions between different electronic states. The approach treats nuclear and electronic degrees of freedom (DOF) equivalently (i.e., by classical mechanics, thereby retaining the simplicity of standard MD), and provides "quantization" of the electronic states through a symmetrical quasi-classical (SQC) windowing model. The approach is seen to be capable of treating extreme regimes of strong and weak coupling between the electronic states, as well as accurately describing coherence effects in the electronic DOF (including the de-coherence of such effects caused by coupling to the nuclear DOF). A survey of recent applications is presented to illustrate the performance of the approach. Also described is a newly developed variation on the original SQC model (found universally superior to the original) and a general extension of the SQC model to obtain the full electronic density matrix (at no additional cost/complexity).
Classic Book Units for G/C/T Youngsters.
ERIC Educational Resources Information Center
Karges-Bone, Linda
1991-01-01
Use of classic book units with gifted elementary students is described as an interdisciplinary approach to stimulating student interest. Sample activities are offered from a unit on Mark Twain's "Huckleberry Finn," with linguistic, artistic-creative, scientific, mathematical, and socio-leadership activities, classified as application,…
Classical versus Computer Algebra Methods in Elementary Geometry
ERIC Educational Resources Information Center
Pech, Pavel
2005-01-01
Computer algebra methods based on results of commutative algebra like Groebner bases of ideals and elimination of variables make it possible to solve complex, elementary and non elementary problems of geometry, which are difficult to solve using a classical approach. Computer algebra methods permit the proof of geometric theorems, automatic…
E-Classical Fairy Tales: Multimedia Builder as a Tool
ERIC Educational Resources Information Center
Eteokleous, Nikleia; Ktoridou, Despo; Tsolakidis, Symeon
2011-01-01
The study examines pre-service teachers' experiences in delivering a traditional-classical fairy tale using the Multimedia Builder software, in other words an e-fairy tale. A case study approach was employed, collecting qualitative data through classroom observations and focus groups. The results focus on pre-service teachers' reactions, opinions,…
Classical Optics and its Applications
NASA Astrophysics Data System (ADS)
Mansuripur, Masud
2009-02-01
Preface; Introduction; 1. Abbe's sine condition; 2. Fourier optics; 3. Effect of polarization on diffraction in systems of high numerical aperture; 4. Gaussian beam optics; 5. Coherent and incoherent imaging; 6. First-order temporal coherence in classical optics; 7. The Van Cittert-Zernike theorem; 8. Partial polarization, Stokes parameters, and the Poincarè Sphere; 9. Second-order coherence and the Hanbury Brown - Twiss experiment; 10. What in the world are surface plasmons?; 11. Surface plasmon polaritons on metallic surfaces; 12. The Faraday effecy; 13. The magneto-optical Kerr effect; 14. The Sagnac interferometer; 15. Fabry-Perot etalons in polarized light; 16. The Ewald-Oseen extinction theorem; 17. Reciprocity in classical Linear optics; 18. Optical pulse compression; 19. The uncertainty principle in classical optics; 20. Omni-directional dielectric mirrors; 21. Optical vortices; 22. Geometric-optical rays, Poynting's vector, and field momenta; 23. Doppler shift, stellar aberration, and convection of light by moving Media; 24. Diffraction gratings; 25. Diffractive optical elements; 26. The talbot effect; 27. Some quirks of total internal reflection; 28. Evanescent coupling; 29. Internal and external conical refraction; 30. Transmission of light through small elliptical apertures; 31. The method of Fox and Li; 32. The beam propagation method; 33. Launching light into a Fiber; 34. The optics of demiconductor fiode Laser; 35. Michelson's dtellar interferometer; 36. Bracewell's interferometric telescope; 37. Scanning optical microscopy; 38. Zernike's method of phase contrast; 39. Polarization microscopy; 40. Nomarski's differential interference contrast microscope; 41. The Van Leeuwenhoek microscope; 42. Projection photolithography; 43. Interaction of light with subwavelength structures; 44 The Ronchi test; 45. The Shack-Hartmann Wavefront sensor; 46. Ellipsometry; 47. Holography and holographic interferometry; 48. Self-focusing in non-linear optical media; 49
Geometrical hierarchies in classical supergravity.
Luo, Hui; Zwirner, Fabio
2014-07-11
We introduce a N=1 supergravity model with a very simple hidden sector coupled to the electroweak gauge and Higgs sectors of the minimal supersymmetric standard model. At the classical level, supersymmetry and SU(2)×U(1) are both spontaneously broken, with vanishing vacuum energy. Two real flat directions control the two symmetry-breaking scales m(3/2) and m(Z). The two massless scalars are a gauge singlet and the standard Higgs boson. All other unobserved particles have masses of order m(3/2). This may be a new starting point for studying the compatibility of naturalness with the observed mass hierarchies.
Superadditivity of classical capacity revisited
Pilyavets, Oleg V.; Karpov, Evgueni A.; Schäfer, Joachim
2014-12-04
We introduce new type of superadditivity for classical capacity of quantum channels, which involves the properties of channels’ environment. By imposing different restrictions on the total energy contained in channels’ environment we can consider different types of superadditivity. Using lossy bosonic and additive noise quantum channels as examples, we demonstrate that their capacities can be either additive or superadditive depending on the values of channels parameters. The parameters corresponding to transition between the additive and superadditive cases are related with recently found critical and supercritical parameters for Gaussian channels.
Classics in Chemical Neuroscience: Haloperidol.
Tyler, Marshall W; Zaldivar-Diez, Josefa; Haggarty, Stephen J
2017-02-15
The discovery of haloperidol catalyzed a breakthrough in our understanding of the biochemical basis of schizophrenia, improved the treatment of psychosis, and facilitated deinstitutionalization. In doing so, it solidified the role for chemical neuroscience as a means to elucidate the molecular underpinnings of complex neuropsychiatric disorders. In this Review, we will cover aspects of haloperidol's synthesis, manufacturing, metabolism, pharmacology, approved and off-label indications, and adverse effects. We will also convey the fascinating history of this classic molecule and the influence that it has had on the evolution of neuropsychopharmacology and neuroscience.
[From classic to new bronchopulmonary dysplasia].
Kramer, Boris W; Lievense, Sanne; Been, Jasper V; Zimmermann, Luc J I
2010-01-01
Chronic lung damage (bronchopulmonary dysplasia (BPD)) is one of the most serious complications affecting preterm neonates. During the last decade the aetiology of BPD has changed. Whereas 'classic BPD' was characterised mainly by lung damage and fibrosis caused by oxygen toxicity and mechanical ventilation, 'new BPD' is characterised by a disorder in lung development. This aetiological shift has been brought about by improved survival in extremely premature infants as a result of, for instance, antenatal corticosteroid administration and postnatal surfactant therapy. New BPD requires a new therapeutic approach. Therapeutic options for developing BPD include caffeine, vitamin A and postnatal corticosteroids. Once BPD has occurred, diuretics and inhaled bronchodilators and corticosteroids may be useful. However, the available therapies decrease the risk of developing BPD by just a small percent. In the future, artificial surfactants and non-invasive ventilation may prove to be useful in the prevention of BPD.
Novel agents in classical Hodgkin lymphoma.
Borchmann, Sven; von Tresckow, Bastian
2017-10-01
Classical Hodgkin lymphoma (cHL) is the most common hematological malignancy in young adults and can be cured in most cases. However, relapsed and refractory Hodgkin lymphoma, certain patient groups, such as elderly patients, and toxicity of first-line treatment still pose significant challenges. Consequently, new treatment options are needed. Recently, many new treatment concepts have been evaluated in clinical trials. Targeted drug-antibody conjugates and immune checkpoint inhibitors have decisively changed treatment approaches. This review aims to give a comprehensive overview of novel agents in Hodgkin lymphoma that have been recently or are currently being evaluated in clinical trials. In addition to dedicated sections on brentuximab vedotin (BV) and immune checkpoint inhibitors, other emerging substances and concepts are discussed. In doing so, this review compares trial results regarding safety and efficacy. A special focus lies on the effect novel agents will have on the different treatment settings faced by clinicians involved in the treatment of Hodgkin lymphoma.