301 research outputs found
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
Modeling bursts and heavy tails in human dynamics
Current models of human dynamics, used from risk assessment to
communications, assume that human actions are randomly distributed in time and
thus well approximated by Poisson processes. We provide direct evidence that
for five human activity patterns the timing of individual human actions follow
non-Poisson statistics, characterized by bursts of rapidly occurring events
separated by long periods of inactivity. We show that the bursty nature of
human behavior is a consequence of a decision based queuing process: when
individuals execute tasks based on some perceived priority, the timing of the
tasks will be heavy tailed, most tasks being rapidly executed, while a few
experiencing very long waiting times. We discuss two queueing models that
capture human activity. The first model assumes that there are no limitations
on the number of tasks an individual can hadle at any time, predicting that the
waiting time of the individual tasks follow a heavy tailed distribution with
exponent alpha=3/2. The second model imposes limitations on the queue length,
resulting in alpha=1. We provide empirical evidence supporting the relevance of
these two models to human activity patterns. Finally, we discuss possible
extension of the proposed queueing models and outline some future challenges in
exploring the statistical mechanisms of human dynamics.Comment: RevTex, 19 pages, 8 figure
System size and centrality dependence of the balance function in A + A collisions at sqrt s NN = 17.2 GeV
Electric charge correlations were studied for p+p, C+C, Si+Si and centrality selected Pb+Pb collisions at sqrt s_NN = 17.2$ GeV with the NA49 large acceptance detector at the CERN-SPS. In particular, long range pseudo-rapidity correlations of oppositely charged particles were measured using the Balance Function method. The width of the Balance Function decreases with increasing system size and centrality of the reactions. This decrease could be related to an increasing delay of hadronization in central Pb+Pb collisions
Individualism and stock price crash risk
Employing a sample of 26,473 firms across 42 countries from 1990 to 2013, we find that firms located in countries with higher individualism have higher stock price crash risk. Furthermore, individualism can be transmitted by foreign investors from overseas markets to influence local firms’ crash risk, and can exacerbate the impact of firm risk taking and earnings management on crash risk. Moreover, the positive relation between individualism and crash risk is amplified during the global financial crisis and attenuated by enhanced country-level financial information transparency and the adoption of International Financial Reporting Standards
Analyzing and Modeling Real-World Phenomena with Complex Networks: A Survey of Applications
The success of new scientific areas can be assessed by their potential for
contributing to new theoretical approaches and in applications to real-world
problems. Complex networks have fared extremely well in both of these aspects,
with their sound theoretical basis developed over the years and with a variety
of applications. In this survey, we analyze the applications of complex
networks to real-world problems and data, with emphasis in representation,
analysis and modeling, after an introduction to the main concepts and models. A
diversity of phenomena are surveyed, which may be classified into no less than
22 areas, providing a clear indication of the impact of the field of complex
networks.Comment: 103 pages, 3 figures and 7 tables. A working manuscript, suggestions
are welcome
Do board secretaries influence management earnings forecasts?
The role of board secretaries is a unique institutional
feature in China. Individuals in this senior executive
role are responsible for coordinating information
disclosure. We study the impact of board secretaries on
management earnings forecasts and find that their legal
expertise, accounting expertise and foreign experience help
improve management earnings forecast quality. The quality
of forecasts, as indicated by their occurrence, frequency,
precision and accuracy, is also positively associated with
the role duality (e.g. board director, CFO or other senior
executive role) and equity holdings of board secretaries and
negatively associated with their political connection. The
quality of forecasts is found to increase the compensation
of board secretaries. Finally, we show that the equity
holding of board secretaries reduces litigation risks and
increases corporate philanthropic giving
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