1,564 research outputs found
Connecting the Micro-dynamics to the Emergent Macro-variables: Self-Organized Criticality and Absorbing Phase Transitions in the Deterministic Lattice Gas
We reinvestigate the Deterministic Lattice Gas introduced as a paradigmatic
model of the 1/f spectra (Phys. Rev. Lett. V26, 3103 (1990)) arising according
to the Self-Organized Criticality scenario. We demonstrate that the density
fluctuations exhibit an unexpected dependence on systems size and relate the
finding to effective Langevin equations. The low density behavior is controlled
by the critical properties of the gas at the absorbing state phase transition.
We also show that the Deterministic Lattice Gas is in the Manna universality
class of absorbing state phase transitions. This is in contrast to expectations
in the literature which suggested that the entirely deterministic nature of the
dynamics would put the model in a different universality class. To our
knowledge this is the first fully deterministic member of the Manna
universality class.Comment: 8 pages, 12 figures. Changes in the new version: Reference list has
been correcte
Accuracy of the cluster-approximation method in a nonequilibrium model
We examine a model in which a nonequilibrium phase transition from an active
to an extinct state is observed. The order of this phase transition has been
shown to be either continuous or first-order, depending on the parameter values
and the dimension of the system. Using increasingly large clusters, we use the
cluster approximation method to obtain estimates for the critical points in 1+1
dimensions. For the continuous phase transitions only, extrapolations of these
approximations show excellent agreement with simulation results. Further, the
approximations suggest that, consistent with simulation results, in 1+1
dimensions no first-order phase transitions are observed.Comment: 8 pages, 3 figures and 1 tabl
Pea-barley intercrop N dynamics in farmers fields
Knowledge about crop performances in farmers’ fields provides a link between on-farm practice and re-search. Thereby scientists may improve their ability to understand and suggest solutions for the problems facing those who have the responsibility of making sound agricultural decisions.
Nitrogen (N) availability is known to be highly heterogeneous in terrestrial plant communities (Stevenson and van Kessel, 1997), a heterogeneity that in natural systems is often associated with variation in the distri-bution of plant species. In intercropping systems the relative proportion of component crops is influenced by the distribution of growth factors such as N in both time and space (Jensen, 1996). In pea-barley intercrops, an increase in the N supply promotes the growth of barley thereby decreasing the N accumulation of pea and giving rise to changes in the relative proportions of the intercropped components (Jensen, 1996). The pres-sure of weeds may, however, significantly change the dynamics in intercrops (Hauggaard-Nielsen et al., 2001). Data from farmers’ fields may provide direct, spatially explicit information for evaluating the poten-tials of improving the utilisation of field variability by intercrops
Probability Models for Degree Distributions of Protein Interaction Networks
The degree distribution of many biological and technological networks has
been described as a power-law distribution. While the degree distribution does
not capture all aspects of a network, it has often been suggested that its
functional form contains important clues as to underlying evolutionary
processes that have shaped the network. Generally, the functional form for the
degree distribution has been determined in an ad-hoc fashion, with clear
power-law like behaviour often only extending over a limited range of
connectivities. Here we apply formal model selection techniques to decide which
probability distribution best describes the degree distributions of protein
interaction networks. Contrary to previous studies this well defined approach
suggests that the degree distribution of many molecular networks is often
better described by distributions other than the popular power-law
distribution. This, in turn, suggests that simple, if elegant, models may not
necessarily help in the quantitative understanding of complex biological
processes.
Three cases of anaphylaxis following injection of a depot corticosteroid with evidence of IgE sensitization to macrogols rather than the active steroid
We present three cases with anaphylaxis after injection of a depot corticosteroid. First, the steroid was suspected as the elicitor, but after evaluation the excipient macrogol was found to be the elicitor. One of the patients had reactions to several unrelated drugs. Increased awareness of anaphylaxis to excipients such as macrogols is needed, especially when allergy tests for the active drug is negative and in patients with a history of repeated anaphylaxis to seemingly unrelated drugs. To establish the correct diagnosis it is important to test with the exact formulation of the culprit drug, as well as all the ingredients including excipients
Blood product ratio in acute traumatic coagulopathy - effect on mortality in a Scandinavian level 1 trauma centre
BACKGROUND: Trauma is the leading cause of loss of life expectancy worldwide. In the most seriously injured patients, coagulopathy is often present on admission. Therefore, transfusion strategies to increase the ratio of plasma (FFP) and platelets (PLT) to red blood cells (RBC), simulating whole blood, have been introduced. Several studies report that higher ratios improve survival in massively bleeding patients. Here, the aim was to investigate the potential effect of increased FFP and PLT to RBC on mortality in trauma patients. METHODS: In a retrospective before and after study, all trauma patients primarily admitted to a level-one Trauma Centre, receiving blood transfusion, in 2001-3 (n = 97) and 2005-7 (n = 156), were included. In 2001-3, FFP and PLT were administered in accordance with the American Society of Anesthesiologists (ASA) guidelines whereas in 2005-7, Hemostatic Control Resuscitation (HCR) entailing pre-emptive use of FFP and PLT in transfusion packages during uncontrolled haemorrhage and thereafter guided by thrombelastograph (TEG) analysis was employed. The effect of transfusion therapy and coagulopathy on mortality was investigated. RESULTS: Patients included in the early and late period had comparable demography, injury severity score (ISS), admission hematology and coagulopathy (27% vs. 34% had APTT above normal). There was a significant change in blood transfusion practice with shorter time interval from admission to first transfusion (median time 3 min vs.28 min in massive bleeders, p < 0.001), transfusion of higher ratios of FFP:RBC, PLT:RBC and PLT:FFP in the HCR group but 30-day mortality remained comparable in the two periods. In the 2005-7 period, higher age, ISS and Activated Partial Thromboplastin Time (APTT) above normal were independent predictors of mortality whereas no association was fund between blood product ratios and mortality. CONCLUSION: Aggressive administration of FFP and PLT did not influence mortality in the present trauma population
Off equilibrium magnetic properties in a model for vortices in superconductors
We study the properties of a simple lattice model of repulsive particles
diffusing in a pinning landscape. The behaviour of the model is very similar to
the observed physics of vortices in superconductors. We compare and discuss the
equilibrium phase diagram, creep dynamics, the Bean state profiles, hysteresis
of magnetisation loops (including the second peak feature), and, in particular,
``off equilibrium'' relaxations. The model is analytically tractable in replica
mean field theory and numerically via Monte Carlo simulations. It offers a
comprehensive schematic framework of the observed phenomenology
- …