29,338 research outputs found
The eggs of marine crabs - an unexploited resource
Marine crabs belonging to the family Portunidae form bycatch of shrimp trawlers in India. They are sold at low prices and consumers discard eggs and consume the meat. The paper details the nutritional value of eggs of Portunus pelagicus
Comment of Global dynamics of biological systems
In a recent study, (Grigorov, 2006) analyzed temporal gene expression
profiles (Arbeitman et al., 2002) generated in a Drosophila experiment using
SSA in conjunction with Monte-Carlo SSA. The author (Grigorov, 2006) makes
three important claims in his article, namely:
Claim1: A new method based on the theory of nonlinear time series analysis is
used to capture the global dynamics of the fruit-fly cycle temporal gene
expression profiles.
Claim 2: Flattening of a significant part of the eigen-spectrum confirms the
hypothesis about an underly-ing high-dimensional chaotic generating process.
Claim 3: Monte-Carlo SSA can be used to establish whether a given time series
is distinguishable from any well-defined process including deterministic chaos.
In this report we present fundamental concerns with respect to the above
claims (Grigorov, 2006) in a systematic manner with simple examples. The
discussion provided especially discourages the choice of SSA for inferring
nonlinear dynamical structure form time series obtained in any biological
paradigm.Comment: 6 pages, 2 figure
A comparison of the efficiency of numerical methods for integrating chemical kinetic rate equations
A comparison of the efficiency of several algorithms recently developed for the efficient numerical integration of stiff ordinary differential equations is presented. The methods examined include two general-purpose codes EPISODE and LSODE and three codes (CHEMEQ, CREK1D, and GCKP84) developed specifically to integrate chemical kinetic rate equations. The codes are applied to two test problems drawn from combustion kinetics. The comparisons show that LSODE is the fastest code currently available for the integration of combustion kinetic rate equations. An important finding is that an iterative solution of the algebraic energy conservation equation to compute the temperature can be more efficient than evaluating the temperature by integrating its time-derivative
Decoupled direct method for sensitivity analysis in combustion kinetics
An efficient, decoupled direct method for calculating the first order sensitivity coefficients of homogeneous, batch combustion kinetic rate equations is presented. In this method the ordinary differential equations for the sensitivity coefficients are solved separately from , but sequentially with, those describing the combustion chemistry. The ordinary differential equations for the thermochemical variables are solved using an efficient, implicit method (LSODE) that automatically selects the steplength and order for each solution step. The solution procedure for the sensitivity coefficients maintains accuracy and stability by using exactly the same steplengths and numerical approximations. The method computes sensitivity coefficients with respect to any combination of the initial values of the thermochemical variables and the three rate constant parameters for the chemical reactions. The method is illustrated by application to several simple problems and, where possible, comparisons are made with exact solutions and those obtained by other techniques
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