4,810 research outputs found
From Individual to Collective Behavior of Unicellular Organisms: Recent Results and Open Problems
The collective movements of unicellular organisms such as bacteria or amoeboid (crawling) cells are often modeled by partial differential equations (PDEs) that describe the time evolution of cell density. In particular, chemotaxis equations have been used to model the movement towards various kinds of extracellular cues. Well-developed analytical and numerical methods for analyzing the time-dependent and time-independent properties of solutions make this approach attractive. However, these models are often based on phenomenological descriptions of cell fluxes with no direct correspondence to individual cell processes such signal transduction and cell movement. This leads to the question of how to justify these macroscopic PDEs from microscopic descriptions of cells, and how to relate the macroscopic quantities in these PDEs to individual-level parameters. Here we summarize recent progress on this question in the context of bacterial and amoeboid chemotaxis, and formulate several open problems
Probing Variant Axion Models at LHC
We study collider implications of variant axion models which naturally avoid
the cosmological domain wall problem. We find that in such models the branching
ratio of can be enhanced by a factor of 5 up to 30 as
compared with the standard model prediction. The process
is therefore a promising channel to discover a light Higgs boson at the LHC and
to probe the Peccei-Quinn charge assignment of the standard model fields from
Yukawa interactions.Comment: 16 pages, 4 figure
Sizes of Minimum Connected Dominating Sets of a Class of Wireless Sensor Networks
We consider an important performance measure of wireless sensor networks, namely, the least number of nodes, N, required to facilitate routing between any pair of nodes, allowing other nodes to remain in sleep mode in order to conserve energy. We derive the expected value and the distribution of N for single dimensional dense networks
Solvable Systems of Linear Differential Equations
The asymptotic iteration method (AIM) is an iterative technique used to find
exact and approximate solutions to second-order linear differential equations.
In this work, we employed AIM to solve systems of two first-order linear
differential equations. The termination criteria of AIM will be re-examined and
the whole theory is re-worked in order to fit this new application. As a result
of our investigation, an interesting connection between the solution of linear
systems and the solution of Riccati equations is established. Further, new
classes of exactly solvable systems of linear differential equations with
variable coefficients are obtained. The method discussed allow to construct
many solvable classes through a simple procedure.Comment: 13 page
Quantifying immediate price impact of trades based on the -shell decomposition of stock trading networks
Traders in a stock market exchange stock shares and form a stock trading
network. Trades at different positions of the stock trading network may contain
different information. We construct stock trading networks based on the limit
order book data and classify traders into classes using the -shell
decomposition method. We investigate the influences of trading behaviors on the
price impact by comparing a closed national market (A-shares) with an
international market (B-shares), individuals and institutions, partially filled
and filled trades, buyer-initiated and seller-initiated trades, and trades at
different positions of a trading network. Institutional traders professionally
use some trading strategies to reduce the price impact and individuals at the
same positions in the trading network have a higher price impact than
institutions. We also find that trades in the core have higher price impacts
than those in the peripheral shell.Comment: 6 pages including 3 figures and 1 tabl
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