Biogeographic and Ecologic Patterns in Calcareous Nannoplankton in the Atlantic and Pacific Oceans During the Terminal Cretaceous

Calcareous nannoplankton biogeography in the Cretaceous ocean has been analyzed from their floral composition at a time-slice spanning the upper parts of the Micula prinsii Zone (approximately the latest 10-60 kyr of the Cretaceous) at DSDP (Deep Sea Drilling Project) sites from low (160) through middle (3 T) paleolatitudes in both the Northern and the Southern Hemisphere. The study is based on relative abundance data of 44 species at Sites 356, 525A, and 527 from the South Atlantic, Sites 384 and 548A from the North Atlantic, and Site 465A from the Pacific Ocean.La biogeografía de nanoplancton calcáreo en el océano Cretácico se ha analizado a partir de su composición floral en un intervalo de tiempo que abarca las partes superiores de la zona Micula prinsii (aproximadamente los últimos 10-60 kyr del Cretácico) en DSDP (Deep Sea Drilling Project). sitios desde bajas (160) hasta medias (3 T) paleolatitudes en el hemisferio norte y sur. El estudio se basa en datos de abundancia relativa de 44 especies en los Sitios 356, 525A y 527 del Atlántico Sur, los Sitios 384 y 548A del Atlántico Norte y el Sitio 465A del Océano Pacífico

Building the Brazilian Academic Genealogy Tree

Along the history, many researchers provided remarkable contributions to science, not only advancing knowledge but also in terms of mentoring new scientists. Currently, identifying and studying the formation of researchers over the years is a challenging task as current repositories of theses and dissertations are cataloged in a decentralized way through many local digital libraries. Following our previous work in which we created and analyzed a large collection of genealogy trees extracted from NDLTD, in this paper we focus our attention on building such trees for the Brazilian research community. For this, we use data from the Lattes Platform, an internationally renowned initiative from CNPq, the Brazilian National Council for Scientific and Technological Development, for managing information about individual researchers and research groups in Brazil

Micro-bias and macro-performance

We use agent-based modeling to investigate the effect of conservatism and partisanship on the efficiency with which large populations solve the density classification task--a paradigmatic problem for information aggregation and consensus building. We find that conservative agents enhance the populations' ability to efficiently solve the density classification task despite large levels of noise in the system. In contrast, we find that the presence of even a small fraction of partisans holding the minority position will result in deadlock or a consensus on an incorrect answer. Our results provide a possible explanation for the emergence of conservatism and suggest that even low levels of partisanship can lead to significant social costs.Comment: 11 pages, 5 figure

On Universality in Human Correspondence Activity

Identifying and modeling patterns of human activity has important ramifications in applications ranging from predicting disease spread to optimizing resource allocation. Because of its relevance and availability, written correspondence provides a powerful proxy for studying human activity. One school of thought is that human correspondence is driven by responses to received correspondence, a view that requires distinct response mechanism to explain e-mail and letter correspondence observations. Here, we demonstrate that, like e-mail correspondence, the letter correspondence patterns of 16 writers, performers, politicians, and scientists are well-described by the circadian cycle, task repetition and changing communication needs. We confirm the universality of these mechanisms by properly rescaling letter and e-mail correspondence statistics to reveal their underlying similarity.Comment: 17 pages, 3 figures, 1 tabl

The aggregation of cytochrome C may be linked to its flexibility during refolding

Large-scale expression of biopharmaceutical proteins in cellular hosts results in production of large insoluble mass aggregates. In order to generate functional product, these aggregates require further processing through refolding with denaturant, a process in itself that can result in aggregation. Using a model folding protein, cytochrome C, we show how an increase in final denaturant concentration decreases the propensity of the protein to aggregate during refolding. Using polarised fluorescence anisotropy, we show how reduced levels of aggregation can be achieved by increasing the period of time the protein remains flexible during refolding, mediated through dilution ratios. This highlights the relationship between the flexibility of a protein and its propensity to aggregate. We attribute this behaviour to the preferential urea-residue interaction, over self-association between molecules

Statistical mixing and aggregation in Feller diffusion

We consider Feller mean-reverting square-root diffusion, which has been applied to model a wide variety of processes with linearly state-dependent diffusion, such as stochastic volatility and interest rates in finance, and neuronal and populations dynamics in natural sciences. We focus on the statistical mixing (or superstatistical) process in which the parameter related to the mean value can fluctuate - a plausible mechanism for the emergence of heavy-tailed distributions. We obtain analytical results for the associated probability density function (both stationary and time dependent), its correlation structure and aggregation properties. Our results are applied to explain the statistics of stock traded volume at different aggregation scales.Comment: 16 pages, 3 figures. To be published in Journal of Statistical Mechanics: Theory and Experimen

How citation boosts promote scientific paradigm shifts and Nobel Prizes

Nobel Prizes are commonly seen to be among the most prestigious achievements of our times. Based on mining several million citations, we quantitatively analyze the processes driving paradigm shifts in science. We find that groundbreaking discoveries of Nobel Prize Laureates and other famous scientists are not only acknowledged by many citations of their landmark papers. Surprisingly, they also boost the citation rates of their previous publications. Given that innovations must outcompete the rich-gets-richer effect for scientific citations, it turns out that they can make their way only through citation cascades. A quantitative analysis reveals how and why they happen. Science appears to behave like a self-organized critical system, in which citation cascades of all sizes occur, from continuous scientific progress all the way up to scientific revolutions, which change the way we see our world. Measuring the "boosting effect" of landmark papers, our analysis reveals how new ideas and new players can make their way and finally triumph in a world dominated by established paradigms. The underlying "boost factor" is also useful to discover scientific breakthroughs and talents much earlier than through classical citation analysis, which by now has become a widespread method to measure scientific excellence, influencing scientific careers and the distribution of research funds. Our findings reveal patterns of collective social behavior, which are also interesting from an attention economics perspective. Understanding the origin of scientific authority may therefore ultimately help to explain, how social influence comes about and why the value of goods depends so strongly on the attention they attract.Comment: 6 pages, 6 figure

Classification of complications of epilepsy surgery and invasive diagnostic procedures: A proposed protocol and feasibility study

Objective: In epilepsy surgery, which aims to treat seizures and thereby to improve the lives of persons with drug-resistant epilepsy, the chances of attaining seizure relief must be carefully weighed against the risks of complications and expected adverse events. The interpretation of data regarding complications of epilepsy surgery and invasive diagnostic procedures is hampered by a lack of uniform definitions and method of data collection. Methods: Based on a review of previous definitions and classifications of complications, we developed a proposal for a new classification. This proposal was then subject to revisions after expert opinion within E-pilepsy, an EU-funded European pilot network of reference centers in refractory epilepsy and epilepsy surgery, later incorporated into the ERN (European Reference Network) EpiCARE. This version was discussed with recognized experts, and a final protocol was agreed to after further revision. The final protocol was evaluated in practical use over 1 year in three of the participating centers. One hundred seventy-four consecutive procedures were included with 35 reported complications. Results: This report presents a multidimensional classification of complications in epilepsy surgery and invasive diagnostic procedures, where complications are characterized in terms of their immediate effects, resulting permanent symptoms, and consequences on activities of daily living. Significance: We propose that the protocol will be helpful in the work to promote safety in epilepsy surgery and for future studies designed to identify risk factors for complications. Further work is needed to address the reporting of outcomes as regards neuropsychological function, activities of daily living, and quality of life

Early risk factors for adolescent antisocial behaviour: an Australian longitudinal study

Objective: This investigation utilizes data from an Australian longitudinal study to identify early risk factors for adolescent antisocial behaviour. Method: Analyses are based on data from the Mater University Study of Pregnancy, an on-going longitudinal investigation of women’s and children’s health and development involving over 8000 participants. Five types of risk factors (child characteristics, perinatal factors, maternal/familial characteristics, maternal pre- and post-natal substance use and parenting practices) were included in analyses and were based on maternal reports, child assessments and medical records. Adolescent antisocial behaviour was measured when children were 14 years old, using the delinquency subscale of the Child Behaviour Checklist. Results: Based on a series of logistic regression models, significant risk factors for adolescent antisocial behaviour included children’s prior problem behaviour (i.e. aggression and attention/restlessness problems at age 5 years) and marital instability, which doubled or tripled the odds of antisocial behaviour. Perinatal factors, maternal substance use, and parenting practices were relatively poor predictors of antisocial behaviour. Conclusions: Few studies have assessed early predictors of antisocial behaviour in Australia and the current results can be used to inform prevention programs that target risk factors likely to lead to problem outcomes for Australian youth