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Dynamic autocorrelation functions for 2.56-ms adjusted intervals of single pulses of PSR 0809+74 have been analyzed. The observations were conducted at 102.5 MHz with 10μs resolution. We find that the neighboring 2.56-ms subpulse intervals seem to have independent microstructure parameters, although sometimes the tendency was observed for the occurrence of quasi-periodic structures of close or double periods within the same subpulse. The distribution of a number of well ordered micropulses in quasi-periodic structures was shown to agree with the hypothesis of a random origin of quasi-periodicities. No relation has been found between the microstructure parameters and subpulse longitude.
During the austral summer field season of the Russian Antarctic Expedition in 1999/2000, wide-angle reflections experiments were performed in the vicinity of the Russian station Vostok. A 60 MHz ice radar system with 12-bit digital recording was used. The measurements were taken along two perpendicular lines directed south–north and east–west with a distance of 200 m between marks. We used a one-layer model (without snow–firn zone influence) for the calculations. We calculate that the average velocity of radio-wave propagation in the ice sheet is168.4 ± 0.5 m μs−1.The same velocity was derived from hyperbolic diffractions from internal discontinuities. The results allow more accurate depth interpretation of radio-echo soundings.
One of the theories of Paleo-Indian migration from Asia to America (Chard 1963) proposes that the most probable route was along the coast of the Sea of Okhotsk through Japan, Kamchatka and the Aleutian islands. To study the problem of New World population origins, we are attempting to correlate archaeological sites in this region. Our aim is to examine connections of the earliest cultures of the Far East and Siberia with the cultures of Sakhalin, the Kurile Islands, Japan and America.
We describe applications of radiocarbon dating used for establishing a chronology of archaeological sites of the Novgorod region at the end of the first millennium ad. We have 14C-dated known-age tree rings from sites in Latvia and ancient Novgorod, northwest Russia, as well as charcoal and wood from Novgorod. Calendar ages of 14C-dated tree rings span the interval, ad 765–999. We used the Groningen calibration program, CAL15 (van der Plicht 1993) to calibrate 14C ages to calendar years. Comparisons between 14C results and archaeological data show good agreement, and enable us to narrow the calendar interval of calibrated 14C determinations.
A reliable archaelogical chronology for medieval sites in northwestern Russia depends in part on a refined regional calibration scale for 14C dates. We present results of dates on tree-ring series from Novgorod that show a systematic discrepancy from European calibration curves, and that underline the need for more extensive 14C dating as the basis of an extended calibration curve for the region.
In a model of dual-agency problems where borrower–lender and bank–nonbank incentives may conflict, we predict a hockey stick relation between bank skin in the game and covenant tightness. As bank participation declines, covenant tightness increases until reaching a low threshold, at which point the relation sharply reverses and covenant protection is removed with a commensurate increase in spread. We find support for the hockey stick relation with bank’s stake in covenant-lite loans averaging 8% (0% median). We also find that covenant-lite loans are more likely when borrower moral hazard is less severe and when bank relationship rents are high.
The paucity of old, isolated accreting neutron stars in ROSAT observations is used to derive a lower limit on the mean velocity of neutron stars at birth. The secular evolution of the population is simulated following the paths of a statistical sample of stars for different values of the initial kick velocity, drawn from an isotropic, Gaussian distribution with mean velocity 0 ≤ 〈V〉 ≤ 550 km s−1. The spin-down, induced by dipole losses and the interaction with the ambient medium, is tracked together with the dynamical evolution in the Galactic potential, allowing for the determination of the fraction of stars which are, at present, in each of the four possible stages: Ejector, Propeller, Accretor, and Georotator. Taking from the ROSAT All-Sky Survey an upper limit of ~ 10 accreting neutron stars within ~ 140 pc from the Sun, we infer a lower bound for the mean kick velocity, 〈V〉 ≳ 200–300 km s−1. The same conclusion is reached for both a constant (B ~ 1012 G) and an exponentially decaying magnetic field with a timescale ~ 109 yr. Present results, moreover, constrain the fraction of low-velocity stars which could have escaped pulsar statistics to ≲ 1%.
Spectra of Active Galactic Nuclei (AGN) indicate that in their central parts a composite motion of emission gas exists. An analysis of broad as well as narrow lines of active galaxies can give information about gas dynamics in central part of these objects (see e.g. Netzer 1990, Osterbrock 1990). Here we present the investigation of the Hβ and O III[4959,5007] line shapes of the two Sy 1 galaxis: Mrk 817 and III Zw2.
About 40 hours of observing data received by the space radio telescope HALCA at L-band (1.6 GHz) were analyzed in order to investigate interference received by the space radio telescope. Autocorrelation spectra for this study were specially prepared at the DRAO S2-correlator with a 7.8125 kHz frequency resolution in each 16 MHz channel. It was found that during 20% of the observing time the interfering signal was above the tolerable level of 1% of total receiver noise in a 16 MHz channel. The major source of interference is identified with uplink communication from ships to geostationary satellites in the International Maritime Satellite service (INMARSAT). The frequency range allocated for INMARSAT is 1636.5–1645.0 MHz. INMARSAT uses four geostationary satellites, two of which are located above the Atlantic Ocean where the strongest interference was observed. To avoid this interference it is recommended to move the HALCA observing frequency range from the currently used 1634–1666 MHz to 1645–1677 MHz. A simple criterion is proposed to predict harmful interference from INMARSAT. This criterion may be used in scheduling of future HALCA observations at L-band.
We report here results of Bi II spectral lines Stark broadening research within the modified semiempirical approach. The strong absorption Bi II lines observed in Hg – Mn star atmospheres have been investigated as well as the influence of the departure from LS – coupling and the correct knowledge of ionization potential. The obtained results have been compared with other estimations and with experimental results.
A space mission to Mars’ moon Phobos with a space vehicle of new generation currently developed by the Russian Aerospace Agency is discussed. The vehicle design incorporates innovative SEP technology focused on small propulsion electric engines which significantly improve the mission energetic capability. The project is optimized around a sample return (PSR) from Phobos and also offers an opportunity for rendezvous/sample return missions from several asteroids, comets, and NEO. Scenario, rationale, and basic profile of PSR mission are presented.
Spices, herbs and medicinal plants as a feed supplements present promising alternatives to antibiotic growth promoters due to their high content of bioactive substances. A large number of experiments have confirmed a wide range of activities of spices in poultry nutrition such as stimulation of feed intake, antimicrobial, antioxidative and coccidiostat stimulation, increase of body weight gain, lowering the mortality rate and improvement of the blood and tissue lipid profile. The present paper gives a review on the characteristics of hot red pepper and its mode of action in broilers nutrition.
The aim of this review paper is to show the most important bioactive compounds of garlic (Allium sativum L.), modes of action of garlic powder and its effects on broiler chicken productive performance. Allicin is thought to be the principal bioactive compound present in aqueous garlic extract or raw garlic homogenate. When garlic is chopped or crushed, the allinase enzyme present in garlic is activated and acts on alliin to produce allicin. Other important sulphur containing compounds present in garlic are allyl methyl thiosulphonate, 1-propenyl allyl thiosulphonate and γ-L-glutamyl-S-alkyl-L-cysteine. These active compounds are thought to influence feed consumption, feed utilisation, body weight, blood lipid profiles and cholesterol levels in chickens. Biological responses to these bioactive compounds have been attributed to a reduction in risk factors for cardiovascular diseases and cancer, stimulation of immune function, enhanced detoxification of foreign compound, hepatoprotection, antimicrobial, antifungal, anti-inflammatory and antioxidant effects.
The observations of bright zenith stars (α Persei and η Ursae Maj) have been carried out in Poltava since 1939. These observations have been used for determining the corrections to semiannual and fortnightly nutation terms and for studying the nearly diurnal free polar motion (Popov, 1968; Popov and Yatskiv, 1977). Recently the reduction of the new series of bright zenith star observations has been finished in Poltava (see Table 1). Therefore it was interesting to carry out a new analysis of these observations for the purpose of studying the nutation and of searching for the nearly diurnal free polar motion.
We propose that observations of ‘hidden’ magnetars in central compact objects can be used to probe crustal activity of neutron stars with large internal magnetic fields. Estimates based on calculations by Perna & Pons, Pons & Rea and Kaminker et al. suggest that central compact objects, which are proposed to be ‘hidden’ magnetars, must demonstrate flux variations on the time scale of months–years. However, the most prominent candidate for the ‘hidden’ magnetars — CXO J1852.6+0040 in Kes 79 — shows constant (within error bars) flux. This can be interpreted by lower variable crustal activity than in typical magnetars. Alternatively, CXO J1852.6+0040 can be in a high state of variable activity during the whole period of observations. Then we consider the source 1E161348 − 5055 in RCW103 as another candidate. Employing a simple 2D-modelling we argue that properties of the source can be explained by the crustal activity of the magnetar type. Thus, this object may be supplemented for the three known candidates for the ‘hidden’ magnetars among central compact objects discussed in literature.
Coccidiosis is well known as an expensive, parasitic disease for the poultry industry worldwide. The disease causes real economic losses by causing poor growth and feed efficiency in broilers even leading to high mortality. Consequently, large amounts of money are being spent on vaccination and inclusion of anticoccidial drugs into diets. In recent years, development of resistance to coccidiostats, elevated costs of systematic vaccination and increasing consumer demand for ′natural′ food products has fuelled the development of natural, plant-based alternatives for coccidial control in poultry farming. The anti-coccidial properties of numerous natural products such as Ageratum conyzoides extract (billy goat weed), green tea, maslinic acid, extracts of Polygonum bistorta (Anjbar) and Agele marmelos (Bael), Artemisia sieberi, Artemisia absinthium, the leaves of Neem (Azadirachta indica), Artemisia annua and Aloa vera-based supplements have been reported. This article summarises the experimental knowledge relating to the efficacy, possible modes of action and different aspects of application of botanical supplements as feed additives for the treatment of poultry diseases, especially coccidiosis.
Fullerite derivatives synthesized with a catalytic polymerization reaction at a relatively low-pressure range of 0.5–4 GPa show unique mechanical properties: elastic recovery is 98% and hardness possibly approaches 100 GPa. Structure of the samples is also unique: one composes from fragments of C60 molecules linked by the covalent bonds. To obtain the homogeneous crack-free samples, we synthesized B4C–fullerite derivatives composite which show a 550 MPa flexural stress, a 2250 MPa compressive strength, and a 28 GPa hardness and have density of 2.2 g/cm3.
The unification model of active galactic nuclei postulates an accreting supermassive black hole as the central engine, surrounded by a putative dusty torus. This dust absorbs the incoming radiation, re-emits it in the infrared and obscures our view of the central region at certain inclinations. We present a new set of AGN models, in which the torus is modelled as a 3D multiphase medium. These new models can explain the observed spectral energy distribution of AGNs over the entire infrared domain, including the observed silicate feature strength and the level of near-infrared continuum. A new generation of multi-phase models, based on hydrodynamical simulations, is being constructed. We will compute the polarisation structure of these physically motivated 3D torus models, and compare them to simpler smooth torus models and to the available observational data.