386 research outputs found
X-ray film chamber with carbon target of Tien-Shan complex array
X-ray films were exposed inside the ionization calorimeter under 74g/sq cm of carbon and 5 cm of lead. The X-ray film chamber area is 35 sq. m. Moving X-ray films were used, 50% of the events, which succeeded to determine incidence time, were identified with corresponding extensive air showers (EAS). For such events the size spectrum of associated EAS was derived. Two methods of energy measurement using X-ray films and ionization calorimeter were compared. The energy transfer from selected hadron to electromagnetic component is illustrated. It is found that in cascades with high energy release into electromagnetic components the hadron component is practically absent
Generation of 10^15 - 10^17 eV photons by UHE CR in the Galactic magnetic filed
We show that the deep expected in the diffuse photon spectrum above the
threshold of e+e- pair production, i.e., at energies 10^15 - 10^17 eV, may be
absent due to the synchrotron radiation by the electron component of the
extragalactic Ultra-High Energy Cosmic Rays (UHE CR) in the Galactic magnetic
filed. The mechanism we propose requires small (less than 2x10^-12 G)
extragalactic magnetic fields and large fraction of photons in the UHE CR. For
a typical photon flux expected in top-down scenarios of UHE CR, the predicted
flux in the region of the deep is close to the existing experimental limit. The
sensitivity of our mechanism to the extragalactic magnetic field may be used to
improve existing bounds on the latter by two orders of magnitude.Comment: 11 pages, LaTeX, 1 .ps figure. Numerical error corrected; references
adde
Cosmic Rays and Large Extra Dimensions
We have proposed that the cosmic ray spectrum "knee", the steepening of the
cosmic ray spectrum at energy E \gsim 10^{15.5} eV, is due to "new physics",
namely new interactions at TeV cm energies which produce particles undetected
by the experimental apparatus. In this letter we examine specifically the
possibility that this interaction is low scale gravity. We consider that the
graviton propagates, besides the usual four dimensions, into an additional
, compactified, large dimensions and we estimate the graviton
production in collisions in the high energy approximation where graviton
emission is factorized. We find that the cross section for graviton production
rises as fast as , where is the fundamental
scale of gravity in dimensions, and that the distribution of
radiating a fraction of the initial particle's energy into gravitational
energy (which goes undetected) behaves as . The missing
energy leads to an underestimate of the true energy and generates a break in
the {\sl inferred} cosmic ray spectrum (the "kne"). By fitting the cosmic ray
spectrum data we deduce that the favorite values for the parameters of the
theory are TeV and .Comment: 8 pages, 1 figur
Doppler shift oscillations in solar spicules
Consecutive height series of Ha spectra in solar limb spicules taken on the
53 cm coronagraph of Abastumani Astrophysical Observatory at the heights of
3800-8700 km above the photosphere have been analyzed. The aim is to observe
oscillatory phenomena in spicules and consequently to trace wave propagations
through the chromosphere. The Discrete Fourier Transform analysis of Ha Doppler
shift time series constructed from the observed spectra at each height is used.
Doppler velocities of solar limb spicules show oscillations with periods of
20-55 and 75-110 s. There is also the clear evidence of 3-min oscillations at
the observed heights. The oscillations can be caused by wave propagations in
thin magnetic flux tubes anchored in the photosphere. We suggest the
granulation as a possible source for the wave excitation. Observed waves can be
used as a tool for spicule seismology; the magnetic field strength in spicules
at the height of about 6000 km above the photosphere is estimated as 12-15 G.Comment: 7 pages, 8 figures, accepted in A&
Russia and "hybrid warfare"
In the aftermath of the Crimea annexation in March 2014, the idea of ‘hybrid warfare’ quickly gained prominence as a concept that could help to explain the success of Russian military operations in this conflict. Although the concept continues to enjoy widespread popularity in both scholarly and policy circles, its utility as an analytical tool is also heavily contested. This article adds to the literature critical of the ‘hybrid warfare’ concept. It argues that in addition to the fact that what is now described as a ‘hybrid’ approach to war is in fact nothing new, the problems pertaining to its utility for the study of contemporary Russia go deeper than this. ‘Hybrid warfare’ inadequately reflects the direction of Russian military modernisation and as such has led to a skewed understanding of Russian military capabilities. Moreover, the tendency to use ‘hybrid warfare’ not only to conceptualise developments in the Russian military, but in the country’s foreign policy in general, can lead to serious unintended consequences
Trophic Relationships and Food Supply of Heterotrophic Animals in the Pelagic Ecosystem of the Black Sea
During recent decades, the Black Sea has been affected by many negative factors that strongly changed the condition of its ecosystem. Especially trophic relationships in the Black Sea pelagic system became very vulnerable influencing the food supply, productivity and abundance of many species and populations of this marine basin. Food is one of most important link between biota and its environment. In this monograph, the role and variability of trophodynamic processes that effect the well-being (health) of main heterotrophic components of ecosystem were analysed in detail for a few key species as indicators for estimation of ecosystem condition in whole. These are most significant mass species of the Black Sea pelagic ecosystem. Among copepods this is Calanus euxinus that dominates the mesozooplankton which makes up the fodder base of planktivorous fishes. Among gelatinous these are medusa Aurelia aurita and the alien ctenophores Mnemiopsis leidyi and Beroe ovata which affected strongly mesozooplankton composition. Lastly among fishes the anchovy Engraulis encrasicolus ponticus and sprat Sprattus sprattus phalericus that dominate small pelagic fishery. We considered in this monograph: • Diel feeding behaviour, in situ feeding rate of Calanus euxinus and impact of mesozooplankton on primary production and phytoplankton biomass. • The effect of vertical migrations on energy budget and its components in C. euxinus; metabolic substrates used in catabolic processes under both aerobic and hypoxic conditions, the role of reserve lipids and effect of abiotic factors on individual growth and population structure of this species. • The intensity and efficiency of ingestion and energy transformation in three gelatinous species ( jellyfish Aurelia aurita, ctenophores Mnemiopsis leidyi and Beroe ovata) and their predatory impact on zooplankton community. • Nutritional condition and food supply of anchovy and sprat in the close interaction with natural biotic and abiotic and anthropogenic factors. • Tendencies in this interaction during long time space: since 1960 s till present years. • Estimation of population condition of these species and its long-term change. This monograph is the collective work of Ukrainian and Turkish scientists studying complex hydrobiological problems of the Black Sea. Its aim is to reveal the significance of nutritional factors on the ecology of Black Sea biota, including changes which have already occurred, as well as offering some insight into changes that may happen in the future. Our joint investigations started in the first half of the 1990s, when conditions for the close cooperation of researchers from the two countries were suitable after the collapse of the Soviet era. This spirit continues to the present day. Professor Ümit Unluata, Director of Erdemli Institute of Marine Sciences (Middle East Technical University, Ankara) was of paramount importance in organising and fostering the work undertaken. We would like to devote this monograph to the memory of him, who died so prematurely. We are also grateful to Academician Professor V. N. Eremeev, Director of the Sevastopol Institute of Biology of the Southern Sea (National Academy of Sciences of Ukraine), and to the directors of Erdemli Institute of Marine Sciences (Professor Ilkay Salihoglu, Professor Sukru Besiktepe and Professor Ferit Bingel) who also made significant contributions to the Ukrainian–Turkish collaboration. We are grateful to Dr Bill Parr from the Black Sea Ecosystem Recovery Project for his valuable efforts in improving earlier drafts. All these investigations were carried out within the framework of the following five NATO linkage-grants: • Pelagic animal food supply in the unstable Black Sea environment, • Will the new alien ctenophore Beroe ovata control the plankton community in the Black Sea? • Grazing, growth and production of Calanus euxinus in the Black Sea, • Bioindicators for assessment of Black Sea ecosystem recovery, • Adaptability and vulnerability of marine species in changing environments. And four TUBITAK - NASU joint projects: • Quantification of the recent ctenophore invader Beroe ovata impact in the Black Sea • Monitoring of the Black Sea anchovy and sprat, • Salinity tolerance as a key factor of invasion success of the copepods of Calanus genus into the Sea of Marmara, • Salinity tolerance as a key factor of invasion success of the mesozooplankton species into the Sea of Marmara. We hope that this publication will make a substantial contribution to future studies of the Black Sea ecosystem and offers further understanding of those features regulating biological processes in this unique marine basin
On inconsistency of experimental data on primary nuclei spectra with sea level muon intensity measurements
For the first time a complete set of the most recent direct data on primary
cosmic ray spectra is used as input into calculations of muon flux at sea level
in wide energy range GeV. Computations have been performed
with the CORSIKA/QGSJET and CORSIKA/VENUS codes. The comparison of the obtained
muon intensity with the data of muon experiments shows, that measurements of
primary nuclei spectra conform to sea level muon data only up to several tens
of GeV and result in essential deficit of muons at higher energies. As it
follows from our examination, uncertainties in muon flux measurements and in
the description of nuclear cascades development are not suitable to explain
this contradiction, and the only remaining factor, leading to this situation,
is underestimation of primary light nuclei fluxes. We have considered
systematic effects, that may distort the results of the primary cosmic ray
measurements with the application of the emulsion chambers. We suggest, that
re-examination of these measurements is required with the employment of
different hadronic interaction models. Also, in our point of view, it is
necessary to perform estimates of possible influence of the fact, that sizable
fraction of events, identified as protons, actually are antiprotons. Study of
these cosmic ray component begins to attract much attention, but today nothing
definite is known for the energies GeV. In any case, to realize whether
the mentioned, or some other reasons are the sources of disagreement of the
data on primaries with the data on muons, the indicated effects should be
thoroughly analyzed
Different sensitivities of rat skeletal muscles and brain to novel anti-cholinesterase agents, alkylammonium derivatives of 6-methyluracil (ADEMS)
BACKGROUND AND PURPOSE The rat respiratory muscle diaphragm has markedly lower sensitivity than the locomotor muscle extensor digitorum longus (EDL) to the new acetylcholinesterase (AChE) inhibitors, alkylammonium derivatives of 6-methyluracil (ADEMS). This study evaluated several possible reasons for differing sensitivity between the diaphragm and limb muscles and between the muscles and the brain. EXPERIMENTAL APPROACH Increased amplitude and prolonged decay time of miniature endplate currents were used to assess anti-cholinesterase activity in muscles. In hippocampal slices, induction of synchronous network activity was used to follow cholinesterase inhibition. The inhibitor sensitivities of purified AChE from the EDL and brain were also estimated. KEY RESULTS The intermuscular difference in sensitivity to ADEMS is partly explained caused by a higher level of mRNA and activity of 1,3-bis[5(diethyl-o-nitrobenzylammonium)pentyl]-6-methyluracildibromide (C-547)-resistant BuChE in the diaphragm. Moreover, diaphragm AChE was more than 20 times less sensitive to C-547 than that from the EDL. Sensitivity of the EDL to C-547 dramatically decreased after treadmill exercises that increased the amount of PRiMA AChE(G4), but not ColQ AChE(A12) molecular forms. The A12 form present in muscles appeared more sensitive to C-547. The main form of AChE in brain, PRiMA AChE(G4), was apparently less sensitive because brain cholinesterase activity was almost three orders of magnitude more resistant to C-547 than that of the EDL. CONCLUSIONS AND IMPLICATIONS Our findings suggest that ADEMS compounds could be used for the selective inhibition of AChEs and as potential therapeutic tools. © 2011 The British Pharmacological Society
- …