1,356 research outputs found
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
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 biogeografĂa de nanoplancton calcáreo en el ocĂ©ano Cretácico se ha analizado a partir de su composiciĂłn floral en un intervalo de tiempo que abarca las partes superiores de la zona Micula prinsii (aproximadamente los Ăşltimos 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 OcĂ©ano PacĂfico
Weblog patterns and human dynamics with decreasing interest
Weblog is the fourth way of network exchange after Email, BBS and MSN. Most
bloggers begin to write blogs with great interest, and then their interests
gradually achieve a balance with the passage of time. In order to describe the
phenomenon that people's interest in something gradually decreases until it
reaches a balance, we first propose the model that describes the attenuation of
interest and reflects the fact that people's interest becomes more stable after
a long time. We give a rigorous analysis on this model by non-homogeneous
Poisson processes. Our analysis indicates that the interval distribution of
arrival-time is a mixed distribution with exponential and power-law feature,
that is, it is a power law with an exponential cutoff. Second, we collect blogs
in ScienceNet.cn and carry on empirical studies on the interarrival time
distribution. The empirical results agree well with the analytical result,
obeying a special power law with the exponential cutoff, that is, a special
kind of Gamma distribution. These empirical results verify the model, providing
an evidence for a new class of phenomena in human dynamics. In human dynamics
there are other distributions, besides power-law distributions. These findings
demonstrate the variety of human behavior dynamics.Comment: 8 pages, 1 figure
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
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
Breast cancer distant recurrence lead time interval by detection method in an institutional cohort.
BACKGROUND: Lead time, the interval between screen detection and when a disease would have become clinically evident, has been cited to explain longer survival times in mammography detected breast cancer cases (BC).
METHODS: An institutional retrospective cohort study of BC outcomes related to detection method (mammography (MamD) vs. patient (PtD)). Cases were first primary invasive stage I-III BC, age 40-74 years (n = 6603), 1999-2016. Survival time was divided into 1) distant disease-free interval (DDFI) and 2) distant disease-specific survival (DDSS) as two separate time interval outcomes. We measured statistical association between detection method and diagnostic, treatment and outcome variables using bivariate comparisons, Cox proportional hazards analyses and mean comparisons. Outcomes were distant recurrence (n = 422), DDFI and DDSS.
RESULTS: 39% of cases were PtD (n = 2566) and 61% were MamD (n = 4037). MamD cases had a higher percentage of Stage I tumors [MamD 69% stage I vs. PtD 31%, p \u3c .001]. Rate of distant recurrence was 11% among PtD BC cases (n = 289) vs. 3% of MamD (n = 133) (p \u3c .001). Order of factor entry into the distant recurrence time interval (DDFI) model was 1) TNM stage (p \u3c .001), 2) HR/HER2 status (p \u3c .001), 3) histologic grade (p = .005) and 4) detection method (p \u3c .001). Unadjusted PtD DDFI mean time was 4.34 years and MamD 5.52 years (p \u3c .001), however when stratified by stage, the most significant factor relative to distant recurrence, there was no significant difference between PtD and MamD BC. Distant disease specific survival time did not differ by detection method.
CONCLUSION: We observed breast cancer distant disease-free interval to be primarily associated with stage at diagnosis and tumor characteristics with less contribution of detection method to the full model. Patient and mammography detected breast cancer mean lead time to distant recurrence differed significantly by detection method for all stages but not significantly within stage with no difference in time from distant recurrence to death. Lead time difference related to detection method appears to be present but may be less influential than other factors in distant disease-free and disease specific survival
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