71,991 research outputs found
Memory Effects and Scaling Properties of Traffic Flows
Traffic flows are studied in terms of their noise of sound, which is an
easily accessible experimental quantity. The sound noise data is studied making
use of scaling properties of wavelet transforms and Hurst exponents are
extracted. The scaling behavior is used to characterize the traffic flows in
terms of scaling properties of the memory function in Mori-Lee stochastic
differential equations. The results obtained provides for a new theoretical as
well as experimental framework to characterize the large-time behavior of
traffic flows. The present paper outlines the procedure by making use of
one-lane computer simulations as well as sound-data measurements from a real
two-lane traffic flow. We find the presence of conventional diffusion as well
as 1/f-noise in real traffic flows at large time scales.Comment: 3 figure
Inverse problems connected with two-point boundary value problems
For the purpose of studying those properties of a nonlinear function for which the two-point boundary value problem , the authors construct a number of kinds of special examples. "Inverse" in the title refers to the fact that the multiplicity is specified first and then a suitable function is constructed
Challenges in modelling dissolved organic matter dynamics in agricultural soil using DAISY
Because dissolved organic matter (DOM) plays an important role is terrestrial C-,N-and P-balances and transport of these three components to aquatic environments, there is a need to include it in models. This paper presents the concept of the newly developed DOM modules implemented in the DAISY model with focus on the quantiďŹcation of DOM sorption/desorption and microbial-driven DOM turnover. The kinetics of DOM sorption/desorption is described by the deviation of the actual DOM concentration in solution from the equilibrium concentration, Ceq. The Ceq is soil speciďŹc and estimated from pedotransfer functions taking into account the soil content of organic matter, Al and Fe oxides. The turnover of several organic matter pools including one DOM pool are described by ďŹrst-order kinetics.
The DOM module was tested at ďŹeld scale for three soil treatments applied after cultivating grassâclover swards. Suction cups were installed at depths 30, 60 and 90 cm and soil solution was sampled for quantiďŹcation of dissolved organic C (DOC) and dissolved organic N (DON). In the topsoil, the observed ďŹuctuations in DOC were successfully simulated when the sorption/desorption rate coefďŹcient k was low. In the subsoil, the observed concentrations of DOC were steadier and the best simulations were obtained using a high k. The model shows that DOC and DON concentrations are levelled out in the subsoils due to soil buffering. The steady concentration levels were based on the Ceq for each horizon and the kinetic concept for sorption/desorption of DOC appeared aviable approach. If Ceq was successfully estimated by the pedotransfer function it was possible to simulate the DOC concentration in the subsoil. In spite of difďŹculties in describing the DOC dynamics of the topsoil, the DOM module simulates the subsoil concentration level of DOC well, and also â but with more uncertainty â the DON concentration level
If You Know Something, Say Something: Young Children's Problem with False Beliefs
Whether young children understand that others may hold false beliefs is a hotly
debated topic in psychology and neuroscience. Much evidence suggests that
children do not pass this milestone in their understanding of other people until
the age of 5 years. Other evidence suggests that they understand already in
their second year. This study proposes a novel account of the logic of
conversations about certain mental states. By modifying the discourse
accordingly, children passed three false belief tasks at 3 years of age while
they failed standard false belief tasks. The results support the view that even
young children construe other people in adult-like psychological terms
Grain Characteristics, Chemical Composition, and Functional Properties of Rye (Secale cereale L.) As Influenced by Genotype and Harvest Year
Grain characteristic, chemical composition, and functional properties of rye were measured in 19 different cultivars grown in one location in up to 3 years. The cultivars included 8 adapted hybrids, 7 adapted population cultivars, and 4 nonadapted population cultivars. The results showed a significant influence of both harvest year and genotype on grain characteristics, chemical composition, and functional properties of the grain. Multivariate data analysis confirmed that the variations in the data were explained by yearly and genotype differences. Calculations of variance components showed that the variations in plant height, harvest yield, and protein content were mainly due to genotype differences and to a lesser extent to differences among harvest years. The kernel weight, hardness index, and content of dietary fiber components, however, were more strongly influenced by the harvest year than by the genotype. Differences in starch properties measured by falling number (FN), amylograph peak viscosity, and temperature at peak viscosity were more strongly influenced by harvest year. The water absorption was strongly influenced by genotype effects, compared to yearly differences. FN and amylograph peak temperature were positively correlated (r = 0.94). No correlation was found between the water absorption and the relative proportion of water-extractable arabinoxylan (AX) compared to the total AX content. However, the degree of ferulic acid cross-linking showed a negative correlation (r = -0.70) with the water absorption
The radiative transfer equations for Compton scattering of polarized low frequency radiation on a hot electron gas
We deduce the equations that describe how polarized radiation is Comptonized
by a hot electron gas. Low frequencies are considered, and the equations are
expanded to second order in electron velocities. Induced scattering terms are
included and a Maxwellian velocity distribution for the electrons is assumed.
The special case of an axisymmetric radiation field is also considered, and the
corresponding radiative transfer equations are found. Our results correct
errors and misprints in previosly published transfer equations. The extension
to a moving electron gas is made, and the radiative transfer equations are
deduced to second order in gas velocity. We use the equations to study
polarization in the Sunyaev-Zeldovich effect.Comment: 9 pages, 2 figuers, MNRAS-LaTeX-style Submitted to the Monthly
Notices of the Royal astronomical Societ
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