121 research outputs found
Chaos induced coherence in two independent food chains
Coherence evolution of two food web models can be obtained under the stirring
effect of chaotic advection. Each food web model sustains a three--level
trophic system composed of interacting predators, consumers and vegetation.
These populations compete for a common limiting resource in open flows with
chaotic advection dynamics. Here we show that two species (the top--predators)
of different colonies chaotically advected by a jet--like flow can synchronize
their evolution even without migration interaction. The evolution is
charaterized as a phase synchronization. The phase differences (determined
through the Hilbert transform) of the variables representing those species show
a coherent evolution.Comment: 5 pages, 5 eps figures. Accepted for publication in Phys. Rev.
Magnetic Phase Diagram and Metal-Insulator Transition of NiS2-xSex
Magnetic phase diagram of NiS2-xSex has been reexamined by systematic studies
of electrical resistivity, uniform magnetic susceptibility and neutron
diffraction using single crystals grown by a chemical transport method. The
electrical resistivity and the uniform magnetic susceptibility exhibit the same
feature of temperature dependence over a wide Se concentration. A distinct
first order metal-insulator (M-I) transition accompanied by a volume change was
observed only in the antiferromagnetic ordered phase for 0.50<x<0.59. In this
region, the M-I transition makes substantial effects to the thermal evolution
of staggered moments. In the paramagnetic phase, the M-I transition becomes
broad; both the electrical resistivity and the uniform magnetic susceptibility
exhibit a broad maximum around the temperatures on the M-I transition-line
extrapolated to the paramagnetic phase.Comment: 6 pages, 8 figures, corrected EPS fil
Bayesian Inference in Processing Experimental Data: Principles and Basic Applications
This report introduces general ideas and some basic methods of the Bayesian
probability theory applied to physics measurements. Our aim is to make the
reader familiar, through examples rather than rigorous formalism, with concepts
such as: model comparison (including the automatic Ockham's Razor filter
provided by the Bayesian approach); parametric inference; quantification of the
uncertainty about the value of physical quantities, also taking into account
systematic effects; role of marginalization; posterior characterization;
predictive distributions; hierarchical modelling and hyperparameters; Gaussian
approximation of the posterior and recovery of conventional methods, especially
maximum likelihood and chi-square fits under well defined conditions; conjugate
priors, transformation invariance and maximum entropy motivated priors; Monte
Carlo estimates of expectation, including a short introduction to Markov Chain
Monte Carlo methods.Comment: 40 pages, 2 figures, invited paper for Reports on Progress in Physic
Study of CP Violating Effects in Time Dependent Decays
We report measurements of time dependent decay rates for decays and extraction of CP violation parameters
containing . Using fully reconstructed events from a data sample collected at the resonance, we obtain
the CP violation parameters for and decays, , where is
the ratio of the magnitudes of the doubly-Cabibbo-suppressed and
Cabibbo-favoured amplitudes, and is the strong phase
difference between them. Under the assumption of being
close to either 0 or , we obtain and .Comment: 9 pages, 3 figures, Submitted to Physical Review Letter
Field-based evidence of fast and global increase of Plasmodium falciparum drug-resistance by DNA-microarrays and PCR/RFLP in Niger
<p>Abstract</p> <p>Background</p> <p>Over the last years, significant progress has been made in the comprehension of the molecular mechanism of malaria resistance to drugs. Together with <it>in vivo </it>tests, the molecular monitoring is now part of the survey strategy of the <it>Plasmodium </it>sensitivity. Currently, DNA-microarray analysis allows the simultaneous study of many single nucleotide polymorphisms (SNP) of <it>Plasmodium </it>isolates. In December 2005, the International Federation of the Red Cross distributed two million three hundred thousand long-lasting insecticide nets to pregnant women and mothers of under five years children in the whole Niger. Then, Niger adopted artemisinin-based combination therapy as first-line treatment.</p> <p>Methods</p> <p>Thirty four SNPs of <it>pfcrt, pfdhfr, pfdhps, pfmdr </it>and <it>pfATPase </it>were analysed by DNA-microarray and PCR/RFLP in two villages – Zindarou and Banizoumbou – with different durations of malaria transmission. The main objective of the study was to measure the dynamics <it>of Plasmodium falciparum </it>resistant strains and associated factors.</p> <p>Results</p> <p>This study shows a global and clear increase of the drug-resistance associated molecular markers frequencies during a relatively short-time period of four years. Markers associated with resistance to chloroquine and sulphonamids were more frequently found in the short transmission zone than in the long transmission one. The <it>pfcrt76T </it>mutation is significantly more present at Banizoumbou than Zindarou (38.3% vs 25.2%, p = 0.013).</p> <p>This work allowed the screening of several field strains for five SNPs of <it>PfATPase6 </it>gene. The <it>pfATPase6S769N</it>, candidate mutation of resistance to artemisinin was not found. However the <it>pfATPsaeA623E </it>mutation was found in 4.7% of samples.</p> <p>Conclusion</p> <p>A significant increase of several SNPs frequencies was highlighted over a four-year period. The polymorphism of five <it>PfATPase6 </it>gene SNPs was described. The global, large and fast increase of the molecular resistance is discussed in the context of current changes of health policy and malaria control in Niger.</p
Syntactic learning by mere exposure - An ERP study in adult learners
<p>Abstract</p> <p>Background</p> <p>Artificial language studies have revealed the remarkable ability of humans to extract syntactic structures from a continuous sound stream by mere exposure. However, it remains unclear whether the processes acquired in such tasks are comparable to those applied during normal language processing. The present study compares the ERPs to auditory processing of simple Italian sentences in native and non-native speakers after brief exposure to Italian sentences of a similar structure. The sentences contained a non-adjacent dependency between an auxiliary and the morphologically marked suffix of the verb. Participants were presented four alternating learning and testing phases. During learning phases only correct sentences were presented while during testing phases 50 percent of the sentences contained a grammatical violation.</p> <p>Results</p> <p>The non-native speakers successfully learned the dependency and displayed an N400-like negativity and a subsequent anteriorily distributed positivity in response to rule violations. The native Italian group showed an N400 followed by a P600 effect.</p> <p>Conclusion</p> <p>The presence of the P600 suggests that native speakers applied a grammatical rule. In contrast, non-native speakers appeared to use a lexical form-based processing strategy. Thus, the processing mechanisms acquired in the language learning task were only partly comparable to those applied by competent native speakers.</p
A next generation, pilot-scale continuous sterilization system for fermentation media
A new continuous sterilization system was designed, constructed, started up, and qualified for media sterilization for secondary metabolite cultivations, bioconversions, and enzyme production. An existing Honeywell Total Distributed Control 3000-based control system was extended using redundant High performance Process Manager controllers for 98 I/O (input/output) points. This new equipment was retrofitted into an industrial research fermentation pilot plant, designed and constructed in the early 1980s. Design strategies of this new continuous sterilizer system and the expanded control system are described and compared with the literature (including dairy and bio-waste inactivation applications) and the weaknesses of the prior installation for expected effectiveness. In addition, the reasoning behind selection of some of these improved features has been incorporated. Examples of enhancements adopted include sanitary heat exchanger (HEX) design, incorporation of a “flash” cooling HEX, on-line calculation of F(o) and R(o), and use of field I/O modules located near the vessel to permit low-cost addition of new instrumentation. Sterilizer performance also was characterized over the expected range of operating conditions. Differences between design and observed temperature, pressure, and other profiles were quantified and investigated
Relationship between the fractal dimension anisotropy of the spatial faults distribution and the paleostress fields on a Variscan granitic massif (Central Spain): the F-parameter
- …