The total number of patents produced by a country (or the number of patents
produced per capita) is often used as an indicator for innovation. Here we
present evidence tha
7b4
t the distribution of patents amongst applicants within
many OECD countries is well-described by power laws with exponents that vary
between 1.66 (Japan) and 2.37 (Poland). Using simulations based on simple
preferential attachment-type rules that generate power laws, we find we can
explain some of the variation in exponents between countries, with countries
that have larger numbers of patents per applicant generally exhibiting smaller
exponents in both the simulated and actual data. Similarly we find that the
exponents for most countries are inversely correlated with other indicators of
innovation, such as R&D intensity or the ubiquity of export baskets. This
suggests that in more advanced economies, which tend to have smaller values of
the exponent, a greater proportion of the total number of patents are filed by
large companies than in less advanced countries.
We propose a model to analyze citation growth and influences of fitness
(competitiveness) factors in an evolving citation network. Applying the
proposed method to modeling citations to papers and scholars in the InfoVis
2004 data, a benchmark collection about a 31-year history of informatio
7bf
n
visualization, leads to findings consistent with citation distributions in
general and observations of the domain in particular. Fitness variables based
on prior impacts and the time factor have significant influences on citation
outcomes. We find considerably large effect sizes from the fitness modeling,
which suggest inevitable bias in citation analysis due to these factors. While
raw citation scores offer little insight into the growth of InfoVis,
normalization of the scores by influences of time and prior fitness offers a
reasonable depiction of the field's development. The analysis demonstrates the
proposed model's ability to produce results consistent with observed data and
to support meaningful comparison of citation scores over time.
FuturICT foundations are social science, complex systems science, and ICT.
The main concerns and challenges in the science of complex systems in the
context of FuturICT are laid out in this paper with special emphasis on the
Complex Systems route to Social Sciences. This include complex systems having:
many heterogeneous interacting parts; multiple scales; complicated transition
laws; unexpected or unpredicted emergence; sensitive dependence on initial
conditions; path-dependent dynamics; networked hierarchical connectivities;
interaction of autonomous agents; self-organisation; non-equilibrium dynamics;
combinatorial explosion; adaptivity to changing environments; co-evolving
subsystems; ill-defined boundaries; and multilevel dynamics. In this context,
science is seen as the process of abstracting the dynamics of systems from
data. This presents many challenges including: data gathering by large-scale
experiment, participatory sensing and social computation, managing huge
distributed dynamic and heterogeneous databases; moving from data to dynamical
models, going beyond correlations to cause-effect relationships, understanding
the relationship between simple and comprehensive models with appropriate
choices of variables, ensemble modeling and data assimilation, modeling systems
of systems of systems with many levels between micro and macro; and formulating
new approaches to prediction, forecasting, and risk, especially in systems that
can reflect on and change their behaviour in response to predictions, and
systems whose apparently predictable behaviour is disrupted by apparently
unpredictable rare or extreme events. These challenges are part of the FuturICT
agenda.
The aim of the paper is to derive for the neg
599
ative correlation function with
a time parameter an asymptotic disjunction of the numerical generalized
least-squares estimator of an unknown constant mean of random field in fact the
correct classic generalized least-squares estimator of an unknown constant mean
of the field.
We derive explicit recursive formulas for Target Close (TC) and
Implementation Shortfall (IS) in the Almgren-Chriss framework. We explain how
to compute the optimal starting and stopping times for IS and TC, respectively,
given a minimum trading size. We also show how to add a minimum participation
rate constraint (Percentage of Volume, PVol) for both TC and IS. We also study
an alternative set of risk measures for the optimisation of algorithmic trading
curves. We assume a self-similar process (e.g. L\'evy process, fractional
Brownian motion or fractal process) and define a new risk measure, the
$p$-variation, which reduces to the variance if the process is a Brownian
motion. We deduce the explicit formula for the TC and IS algorithms under a
self-similar process. We show that there is an equivalence between self-similar
models and a family of risk measures called $p$-variations: assuming a
self-similar process and calibrating empirically the parameter $p$ for the
$p$-variation yields the same result as assuming a Brownian motion and using
the $p$-variation as risk measure instead of the variance. We also show that
$p$ can be seen as a measure of the aggressiveness: $p$ increases if and only
if the TC algorithm starts later and executes faster. From the explicit
expression of the TC algorithm one can compute the sensitivities of the curve
with respect to the parameters up to any order. As an example, we compute the
first order sensitivity with respect to both a local and a global surge of
volatility. Finally, we show how the parameter $p$ of the $p$-variation can be
implied from the optimal starting time of TC, and that under this framework $p$
can be viewed as a measure of the joint impact of market impact (i.e.
liquidity) and volatility.