Effect of radiation from vacuum in the interaction of zero-point fluctuations with charged particles accelerated in electric or magnetic fields

The possibility of the effect of electromagnetic radiation (hereinafter - radiation from vacuum) due to the interaction of zero-point vacuum fluctuations with free charged particles accelerated at relativistic speeds in electric or magnetic fields is theoretically demonstrated and confirmed by calculations. The proposed effect is similar to the appearance of radiation in the Lamb shift effect in the hydrogen atom and the dynamical Casimir effect. However, unlike these effects, the radiation characteristics depend on the induction of electric or magnetic fields. Moreover, in order to comply with the law of conservation of momentum, the braking radiation of charged particles is considered as the "third body". As opposed to this bremsstrahlung, radiation from vacuum will not have a preferred direction. Analytical expressions describing the radiation characteristics were obtained using a semi-classical method. The calculated values of the energy and intensity of radiation from vacuum demonstrate the possibility of using optical methods to determine the characteristics of such radiation in strong electric or magnetic fields. The results of the work can be used in studies of astrophysical objects with powerful electric or magnetic fields, as well as in investigations of physical vacuum states under laboratory conditions.Comment: 6 page

II-3. アルゼンチンにおける Medicago 属遺伝資源の探索・収集, 1989年

1. Joint exploration for collecting Medicago in Argentina 1989 was planned by Agriculture, Forestry and Fisheries Research Council (AFFRC), and conducted by AFFRC Secretariat, Nat. Inst. Agrobiological Resources, Nat. Grassland Research Inst. of Japan and National Institute of Agricultural Technology (INTA) of Argentina. 2. The period of the exploration was 37 days, from January 14th till February 19th in 1989. It was maturity and harvest season of Medicago in Argentina, and so optimum period to collect seeds from fields and farmer\u27s stores. 3. The expedition drove a car of INTA throughout all the course about 11, 000 km through the provinces of Cordoba, Santiago del Estero, Salta, Catamarca, La Rioja, San Juan, Mendoza, La Pampa and Santa Fe. These areas are located in from 25 to 38 degree of south latitude, and from lowlands to 2, 850 m elevation. 4. There were almost neither escaped nor weedy populations of Medicago in Argentina due to severe environmental conditions (drought, small animal, etc.). 5. One hundred and twenty nine seed lots were collected from pasture, meadow, field, and store of farmers, cooperatives, institutes, seed companies etc. They were mainly native strains (called ecotipo) and some bred varieties. 6. The seed lots taken from very salty fields in Santiago del Estero and high elevation pastures in Salta and dry meadow in La Pampa may be interested germplasm especially for salt, cold and drought resistance varieties respectively. The authors wish to express their sincere gratitude to Dr. K. A. Okada, Coordinator Genetic Resources Program INTA, Ing. Agr. A. G. Cragnoz, Coordinator Alfalfa Program INTA, Dr. E. Hijano, EEA Manfredi INTA, Dr. L. H. Ochoa, EEA Sanchago del Estero INTA, Ing. Agr. R. A. Neumann, EEA Salta INTA, Ing. Agr. H. Vicente, EEA Anguil INTA, and many coworkers in INTA for the arrangement and assistances of the collection tour. Furthermore the authors make a grateful acknowledgment to Mr. A. Nanbu, prime secretary of Japanese Embassy in Argentina, and Messrs S. Kamimura, M. Aoki, T. Ezuka, Japanese International Cooperation Agency in Argentina, for kindly supports during their stay in Argentina

Multi-Timescale Perceptual History Resolves Visual Ambiguity

When visual input is inconclusive, does previous experience aid the visual system in attaining an accurate perceptual interpretation? Prolonged viewing of a visually ambiguous stimulus causes perception to alternate between conflicting interpretations. When viewed intermittently, however, ambiguous stimuli tend to evoke the same percept on many consecutive presentations. This perceptual stabilization has been suggested to reflect persistence of the most recent percept throughout the blank that separates two presentations. Here we show that the memory trace that causes stabilization reflects not just the latest percept, but perception during a much longer period. That is, the choice between competing percepts at stimulus reappearance is determined by an elaborate history of prior perception. Specifically, we demonstrate a seconds-long influence of the latest percept, as well as a more persistent influence based on the relative proportion of dominance during a preceding period of at least one minute. In case short-term perceptual history and long-term perceptual history are opposed (because perception has recently switched after prolonged stabilization), the long-term influence recovers after the effect of the latest percept has worn off, indicating independence between time scales. We accommodate these results by adding two positive adaptation terms, one with a short time constant and one with a long time constant, to a standard model of perceptual switching

Contribution of mixing to the upward transport across the TTL

International audienceDuring the second part of the TROCCINOX campaign that took place in Brazil in early 2005, chemical species were measured on-board of the high altitude research aircraft Geophysica (ozone, water vapor, NO, NOy, CH4 and CO) in the altitude range up to 20 km (or up to 450 K potential temperature), i.e. spanning the TTL region roughly extending between 350 and 420 K. Analysis of transport across TTL is performed using a new version of the Chemical Lagrangian Model of the Stratosphere (CLaMS). In this new version, the stratospheric model has been extended to the earth surface. Above the tropopause, the isentropic and cross-isentropic advection in CLaMS is driven by ECMWF winds and heating/cooling rates derived from a radiation calculation. Below the tropopause the model smoothly transforms from the isentropic to hybrid-pressure coordinate and, in this way, takes into account the effect of large-scale convective transport as implemented in the ECMWF vertical wind. As with other CLaMS simulations, the irreversible transport, i.e. mixing, is controlled by the local horizontal strain and vertical shear rates. Stratospheric and tropospheric signatures in the TTL can be seen both in the observation and in the model. The composition of air above ?350 K is mainly controlled by mixing on a time scale of weeks or even months. Based on CLaMS transport studies where mixing can be completely switched off, we deduce that vertical mixing, mainly driven by the vertical shear in the outflow regions of the large-scale convection and in the vicinity of the subtropical jets, is necessary to understand the upward transport of the tropospheric air from the main convective outflow around 350 K up to the tropical tropopause around 380 K. This mechanism is most effective if the outflow of the mesoscale convective systems interacts with the subtropical jets

Active Control of Acoustic Field-of-View in a Biosonar System

Echolocating bats can actively change the area scanned by their biosonar sensory system (“field of view”), and they do so according to the complexity of the environment and depending on the distance to the target

A Neurocomputational Model of Stimulus-Specific Adaptation to Oddball and Markov Sequences

Stimulus-specific adaptation (SSA) occurs when the spike rate of a neuron decreases with repetitions of the same stimulus, but recovers when a different stimulus is presented. It has been suggested that SSA in single auditory neurons may provide information to change detection mechanisms evident at other scales (e.g., mismatch negativity in the event related potential), and participate in the control of attention and the formation of auditory streams. This article presents a spiking-neuron model that accounts for SSA in terms of the convergence of depressing synapses that convey feature-specific inputs. The model is anatomically plausible, comprising just a few homogeneously connected populations, and does not require organised feature maps. The model is calibrated to match the SSA measured in the cortex of the awake rat, as reported in one study. The effect of frequency separation, deviant probability, repetition rate and duration upon SSA are investigated. With the same parameter set, the model generates responses consistent with a wide range of published data obtained in other auditory regions using other stimulus configurations, such as block, sequential and random stimuli. A new stimulus paradigm is introduced, which generalises the oddball concept to Markov chains, allowing the experimenter to vary the tone probabilities and the rate of switching independently. The model predicts greater SSA for higher rates of switching. Finally, the issue of whether rarity or novelty elicits SSA is addressed by comparing the responses of the model to deviants in the context of a sequence of a single standard or many standards. The results support the view that synaptic adaptation alone can explain almost all aspects of SSA reported to date, including its purported novelty component, and that non-trivial networks of depressing synapses can intensify this novelty response

Universality in Systems with Power-Law Memory and Fractional Dynamics

There are a few different ways to extend regular nonlinear dynamical systems by introducing power-law memory or considering fractional differential/difference equations instead of integer ones. This extension allows the introduction of families of nonlinear dynamical systems converging to regular systems in the case of an integer power-law memory or an integer order of derivatives/differences. The examples considered in this review include the logistic family of maps (converging in the case of the first order difference to the regular logistic map), the universal family of maps, and the standard family of maps (the latter two converging, in the case of the second difference, to the regular universal and standard maps). Correspondingly, the phenomenon of transition to chaos through a period doubling cascade of bifurcations in regular nonlinear systems, known as "universality", can be extended to fractional maps, which are maps with power-/asymptotically power-law memory. The new features of universality, including cascades of bifurcations on single trajectories, which appear in fractional (with memory) nonlinear dynamical systems are the main subject of this review.Comment: 23 pages 7 Figures, to appear Oct 28 201

Repertoires of the Nucleosome-Positioning Dinucleotides

It is generally accepted that the organization of eukaryotic DNA into chromatin is strongly governed by a code inherent in the genomic DNA sequence. This code, as well as other codes, is superposed on the triplets coding for amino acids. The history of the chromatin code started three decades ago with the discovery of the periodic appearance of certain dinucleotides, with AA/TT and RR/YY giving the strongest signals, all with a period of 10.4 bases. Every base-pair stack in the DNA duplex has specific deformation properties, thus favoring DNA bending in a specific direction. The appearance of the corresponding dinucleotide at the distance 10.4 xn bases will facilitate DNA bending in that direction, which corresponds to the minimum energy of DNA folding in the nucleosome. We have analyzed the periodic appearances of all 16 dinucleotides in the genomes of thirteen different eukaryotic organisms. Our data show that a large variety of dinucleotides (if not all) are, apparently, contributing to the nucleosome positioning code. The choice of the periodical dinucleotides differs considerably from one organism to another. Among other 10.4 base periodicities, a strong and very regular 10.4 base signal was observed for CG dinucleotides in the genome of the honey bee A. mellifera. Also, the dinucleotide CG appears as the only periodical component in the human genome. This observation seems especially relevant since CpG methylation is well known to modulate chromatin packing and regularity. Thus, the selection of the dinucleotides contributing to the chromatin code is species specific, and may differ from region to region, depending on the sequence context