105 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
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
Probabilistic 3-D time-lapse inversion of magnetotelluric data: application to an enhanced geothermal system
Second Language Processing Shows Increased Native-Like Neural Responses after Months of No Exposure
Although learning a second language (L2) as an adult is notoriously difficult, research has shown that adults can indeed attain native language-like brain processing and high proficiency levels. However, it is important to then retain what has been attained, even in the absence of continued exposure to the L2—particularly since periods of minimal or no L2 exposure are common. This event-related potential (ERP) study of an artificial language tested performance and neural processing following a substantial period of no exposure. Adults learned to speak and comprehend the artificial language to high proficiency with either explicit, classroom-like, or implicit, immersion-like training, and then underwent several months of no exposure to the language. Surprisingly, proficiency did not decrease during this delay. Instead, it remained unchanged, and there was an increase in native-like neural processing of syntax, as evidenced by several ERP changes—including earlier, more reliable, and more left-lateralized anterior negativities, and more robust P600s, in response to word-order violations. Moreover, both the explicitly and implicitly trained groups showed increased native-like ERP patterns over the delay, indicating that such changes can hold independently of L2 training type. The results demonstrate that substantial periods with no L2 exposure are not necessarily detrimental. Rather, benefits may ensue from such periods of time even when there is no L2 exposure. Interestingly, both before and after the delay the implicitly trained group showed more native-like processing than the explicitly trained group, indicating that type of training also affects the attainment of native-like processing in the brain. Overall, the findings may be largely explained by a combination of forgetting and consolidation in declarative and procedural memory, on which L2 grammar learning appears to depend. The study has a range of implications, and suggests a research program with potentially important consequences for second language acquisition and related fields
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