2,694 research outputs found
Streekdorpen en lintbebouwing in de provincie Groningen : inventarisatie topografische- en bevolkingskenmerken
The block copolymer shuffle in size exclusion chromatography: the intrinsic problem with using elugrams to determine chain extension success
On the General Analytical Solution of the Kinematic Cosserat Equations
Based on a Lie symmetry analysis, we construct a closed form solution to the
kinematic part of the (partial differential) Cosserat equations describing the
mechanical behavior of elastic rods. The solution depends on two arbitrary
analytical vector functions and is analytical everywhere except a certain
domain of the independent variables in which one of the arbitrary vector
functions satisfies a simple explicitly given algebraic relation. As our main
theoretical result, in addition to the construction of the solution, we proof
its generality. Based on this observation, a hybrid semi-analytical solver for
highly viscous two-way coupled fluid-rod problems is developed which allows for
the interactive high-fidelity simulations of flagellated microswimmers as a
result of a substantial reduction of the numerical stiffness.Comment: 14 pages, 3 figure
An Estimate of the Vibrational Frequencies of Spherical Virus Particles
The possible normal modes of vibration of a nearly spherical virus particle
are discussed. Two simple models for the particle are treated, a liquid drop
model and an elastic sphere model. Some estimates for the lowest vibrational
frequency are given for each model. It is concluded that this frequency is
likely to be of the order of a few GHz for particles with a radius of the order
of 50 nm.Comment: 6 pages, 1 figur
Role of Solvent Compatibility in the Phase Behavior of Binary Solutions of Weakly Associating Multivalent Polymers
[Image: see text] Condensate formation of biopolymer solutions, prominently those of various intrinsically disordered proteins (IDPs), is often driven by “sticky” interactions between associating residues, multivalently present along the polymer backbone. Using a ternary mean-field “stickers-and-spacers” model, we demonstrate that if sticker association is of the order of a few times the thermal energy, a delicate balance between specific binding and nonspecific polymer–solvent interactions gives rise to a particularly rich ternary phase behavior under physiological circumstances. For a generic system represented by a solution comprising multiassociative scaffold and client polymers, the difference in solvent compatibility between the polymers modulates the nature of isothermal liquid–liquid phase separation (LLPS) between associative and segregative. The calculations reveal regimes of dualistic phase behavior, where both types of LLPS occur within the same phase diagram, either associated with the presence of multiple miscibility gaps or a flip in the slope of the tie-lines belonging to a single coexistence region
USING THE CUMULATIVE-SIZE MECHANISTIC MODEL FOR ANALYZING INSECT DATA
Two data sets of aphid abundance are analyzed using a new cumulative-size based mechanistic model. The first data set pertains to the cotton aphid, and its analysis demonstrates the power of the mechanistic model-based approach. The second data set pertains to greenbug populations, and its analysis shows the key role that birth and death rate coefficients may play in predicting the peak and the cumulative population sizes
Domain walls and perturbation theory in high temperature gauge theory: SU(2) in 2+1 dimensions
We study the detailed properties of Z_2 domain walls in the deconfined high
temperature phase of the d=2+1 SU(2) gauge theory. These walls are studied both
by computer simulations of the lattice theory and by one-loop perturbative
calculations. The latter are carried out both in the continuum and on the
lattice. We find that leading order perturbation theory reproduces the detailed
properties of these domain walls remarkably accurately even at temperatures
where the effective dimensionless expansion parameter, g^2/T, is close to
unity. The quantities studied include the surface tension, the action density
profiles, roughening and the electric screening mass. It is only for the last
quantity that we find an exception to the precocious success of perturbation
theory. All this shows that, despite the presence of infrared divergences at
higher orders, high-T perturbation theory can be an accurate calculational
tool.Comment: 75 pages, LaTeX, 14 figure
COMPARISONS OF TWO SYMMETRIC DENSITY FUNCTION SOLUTIONS OF APHID POPULATION GROWTH MODELS
Aphids are among the world\u27s most devastating crop pests, and their population trajectories in field crops are characterized by rapid boom and bust, under the influence of bottom up (host plant) and top down (natural enemy) forces. Theoretical development in aphid growth trajectory modeling has recently advanced quite significantly, and the logistic and normal probability density functions have been found to provide analytical solutions to mechanistic models of the aphid population growth dynamics. The logistic or hyperbolic secant squared model captures a growth trajectory shaped by negative feedback of the aphid population on itself, due to the accumulation of adverse effect on its host plant and the coupling with natural enemies (bottom up as well as top down effect), while the normal model can be derived on the basis of a relationship between intrinsic growth rate and the host plant phenology. In this paper, we fit both models to a large number of observed aphid population trajectors and explore model properties. It is shown that, despite the diverging mechanistic underpinnings of the model, the generated growth curves, as fitted to the data, are very similar, as are characteristics, such as the height of the peak, the time of the peak and the accumulated area under the curve. Both models are useful workhorses for capturing aphid growth dynamics, but fitting one or either model cannot be used as evidence for the underpinning mechanisms, as different underpinning mechanisms result in similar population dynamics
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