170 research outputs found
Radio emission from cosmic ray air showers: simulation results and parametrization
We have developed a sophisticated model of the radio emission from extensive
air showers in the scheme of coherent geosynchrotron radiation, providing a
theoretical foundation for the interpretation of experimental data from current
and future experiments. Having verified the model through comparison of
analytic calculations, Monte Carlo simulations and historical experimental
data, we now present the results of extensive simulations performed with our
Monte Carlo code. Important results are the absence of significant asymmetries
in the total field strength emission pattern, the spectral dependence of the
radiation, the polarization characteristics of the emission (allowing an
unambiguous test of the geomagnetic emission mechanism), and the dependence of
the radio emission on important air shower and observer parameters such as the
shower zenith angle, the primary particle energy, the depth of the shower
maximum and the observer position. An analytic parametrization incorporating
the aforementioned dependences summarizes our results in a particularly useful
way.Comment: 33 pages, 24 figures, final version as accepted for publication by
Astropart. Physics, only minor updates since V
Bi-enzyme sensor based on thick-film carbon electrode modified with electropolymerized tyramine
Bi-enzyme sensor based on thick-film epoxy-carbon electrode modified with polytyramine has been developed and examined for the determination of peroxidase substrates and cholinesterase inhibitors. Polytyramine was obtained on the electrode surface by repeated scanning of the potential from +600 to +1800 mV vs. Ag/AgCl in tyramine solution. The enzymes were immobilized in the polytyramine matrix by cross-linking with glutaraldehyde. The biosensor developed provides a reliable and inexpensive way for preliminary testing of common environmental pollutants with a single sensor in accordance with assumed toxic effect by the choice of appropriate substrate and measurement conditions. The bi-enzyme sensor makes it possible to determine substituted phenols and aromatic amines in the micromolar range of their concentrations and anticholinesterase pesticides with detection limits of 0.1 (Coumaphos) and 0.03 Όmol l-1 (Chloropyrifos-methyl). © 2004 Published by Elsevier B.V
The Institutions of «Green Economy» for Sustainable Development of Agrarian Sector: Theoretical Dimension
The article is aimed at substantiating the conceptual foundations and theoretical positions of the place and role of institutions in formation of the «green economy» in the context of implementation of the principles for sustainable development of agrarian sector. The article reflects the main scientific concepts that are directed to address the problems of environmentally oriented development, in particular the concepts of ecotopia, anthropocentrism, ecocentrism, biocentrism, and the concept of sustainable development. It has been found that the conceptual foundations for sustainable development include ecologization of economy, humanization of production, introducing a system of principled approaches to public affairs. The general provisions of formation of «green economy» have been characterized and its key principles have been provided. The role and value of institutions in the organizational provision of the sustainable development of agrarian sector, which, in the organizational-economic, coordinating and enabling aspects are the key driver for harmonization of the interaction of all participants in economic relations, have been substantiated
Radio emission from cosmic ray air showers: Monte Carlo simulations
We present time-domain Monte Carlo simulations of radio emission from cosmic
ray air showers in the scheme of coherent geosynchrotron radiation. Our model
takes into account the important air shower characteristics such as the lateral
and longitudinal particle distributions, the particle track length and energy
distributions, a realistic magnetic field geometry and the shower evolution as
a whole. The Monte Carlo approach allows us to retain the full polarisation
information and to carry out the calculations without the need for any
far-field approximations. We demonstrate the strategies developed to tackle the
computational effort associated with the simulation of a huge number of
particles for a great number of observer bins and illustrate the robustness and
accuracy of these techniques. We predict the emission pattern, the radial and
the spectral dependence of the radiation from a prototypical 10^17 eV vertical
air shower and find good agreement with our analytical results (Huege & Falcke
2003) and the available historical data. Track-length effects in combination
with magnetic field effects surprisingly wash out any significant asymmetry in
the total field strength emission pattern in spite of the magnetic field
geometry. While statistics of total field strengths alone can therefore not
prove the geomagnetic origin, the predicted high degree of polarisation in the
direction perpendicular to the shower and magnetic field axes allows a direct
test of the geomagnetic emission mechanism with polarisation-sensitive
experiments such as LOPES. Our code provides a robust, yet flexible basis for
detailed studies of the dependence of the radio emission on specific shower
parameters and for the inclusion of additional radiation mechanism in the
future.Comment: 21 pages, version accepted for publication by Astronomy &
Astrophysic
Acetylcholinesterase sensor based on screen-printed carbon electrode modified with prussian blue
Acetylcholinesterase (ChE) sensor based on Prussian blue (PB) modified electrode was developed and tested for the detection of organophosphorus and carbamic pesticides. The signal of the sensor was generated in PB mediated oxidation of thiocholine recorded at+200 mv in DC mode. ChE from electric eel was immobilized by cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) on the surface of screen-printed carbon electrode covered with PB and Nafion. The content of the surface layer (specific enzyme activity, Nafion and BSA amounts) was optimized to establish high and reliable response toward the substrate and ChE inhibitors. The ChE/PB sensor makes it possible to detect Aldicarb, Paraoxon and Parathion-Methyl with limits of detection 30, 10 and 5 ppb, respectively (incubation 10 min). The feasibility of practical application of the ChE/PB sensor developed for the monitoring of degradation of the pesticides in wine fermentation was shown. To diminish matrix interferences, the electrolysis of the grape juice with Al anode and evaporation of ethanol were suggested, however the procedures decrease the sensitivity of pesticide detection and stability of the sample tested. © Springer-Verlag 2005
Optimal Radio Window for the Detection of Ultra-High-Energy Cosmic Rays and Neutrinos off the Moon
When high-energy cosmic rays impinge on a dense dielectric medium, radio
waves are produced through the Askaryan effect. We show that at wavelengths
comparable to the length of the shower produced by an Ultra-High Energy cosmic
ray or neutrino, radio signals are an extremely efficient way to detect these
particles. Through an example it is shown that this new approach offers, for
the first time, the realistic possibility of measuring UHE neutrino fluxes
below the Waxman-Bahcall limit. It is shown that in only one month of observing
with the upcoming LOFAR radio telescope, cosmic-ray events can be measured
beyond the GZK-limit, at a sensitivity level of two orders of magnitude below
the extrapolated values.Comment: Submitted to Astroparticle Physic
Prospects for radio detection of ultra-high energy cosmic rays and neutrinos
The origin and nature of the highest energy cosmic ray events is currently
the subject of intense investigation by giant air shower arrays and fluorescent
detectors. These particles reach energies well beyond what can be achieved in
ground-based particle accelerators and hence they are fundamental probes for
particle physics as well as astrophysics. Because of the scarcity of these
high-energy particles, larger and larger ground-based detectors have been
built. The new generation of digital radio telescopes may play an important
role in this, if properly designed. Radio detection of cosmic ray showers has a
long history but was abandoned in the 1970's. Recent experimental developments
together with sophisticated air shower simulations incorporating radio emission
give a clearer understanding of the relationship between the air shower
parameters and the radio signal, and have led to resurgence in its use.
Observations of air showers by the SKA could, because of its large collecting
area, contribute significantly to measuring the cosmic ray spectrum at the
highest energies. Because of the large surface area of the moon, and the
expected excellent angular resolution of the SKA, using the SKA to detect radio
Cherenkov emission from neutrino-induced cascades in lunar regolith will be
potentially the most important technique for investigating cosmic ray origin at
energies above the photoproduction cut-off. (abridged)Comment: latex, 26 pages, 17 figures, to appear in: "Science with the Square
Kilometer Array," eds. C. Carilli and S. Rawlings, New Astronomy Reviews,
(Elsevier: Amsterdam
Measuring the Relative Strong Phase in and Decays
In a recently suggested method for measuring the weak phase in
decays, the relative strong phase in and decays (equivalently, in and \od \to K^{*+} K^-) plays a role. It is shown how a study of
the Dalitz plot in can yield information on this phase,
and the size of the data sample which would give a useful measurement is
estimated.Comment: 13 pages, latex, 5 figures, submitted to Phys. Rev. D. Appendix and
some text on additional resonant contributions adde
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