346 research outputs found
Maser Oscillation in a Whispering-Gallery-Mode Microwave Resonator
We report the first observation of above-threshold maser oscillation in a
whispering-gallery(WG)-mode resonator, whose quasi-transverse-magnetic, 17th
azimuthal-order WG mode, at a frequency of approx. 12.038 GHz, with a loaded Q
of several hundred million, is supported on a cylinder of mono-crystalline
sapphire. An electron spin resonance (ESR) associated with Fe3+ ions, that are
substitutively included within the sapphire at a concentration of a few parts
per billion, coincides in frequency with that of the (considerably narrower) WG
mode. By applying a c.w. `pump' to the resonator at a frequency of approx.
31.34 GHz, with no applied d.c. magnetic field, the WG (`signal') mode is
energized through a three-level maser scheme. Preliminary measurements
demonstrate a frequency stability (Allan deviation) of a few times 1e-14 for
sampling intervals up to 100 s.Comment: REVTeX v.4, 3 pages, with a separate .bbl file and 3 .eps figure
ISOLATION OF BACTERIOPHAGES, CAPABLE TO LYSE SERRATIA MARCESCENS AND EVALUATION OF THEIR ACTIVITY ON ONION AND GERANIUM
In this study, phages active against S. marcescens, causative agent of onion decay, were isolated from plant material. One virus isolate was shown to accumulate in high titers and was denoted as phage S. This bacteriophage exhibited a hexagonal head and tail and was attributed to Myoviridae family. It was shown the ability of bacteriophage S to suppress the development of bacteriosis on geranium plants. Investigated virus isolate also inhibited rooting of onion scales. This work focused on a biological control approach to use bacteriophages for reducing bacterial pathogen populations and disease severity on plants
Phenomena induced by powerful HF pumping towards magnetic zenith with a frequency near the F-region critical frequency and the third electron gyro harmonic frequency
Multi-instrument observational data from an experiment on 13 October 2006 at the EISCAT/HEATING facility at Tromsø, Norway are analysed. The experiment was carried out in the evening hours when the electron density in the F-region dropped, and the HF pump frequency <I>f<sub>H</sub></I> was near and then above the critical frequency of the F2 layer. The distinctive feature of this experiment is that the pump frequency was just below the third electron gyro harmonic frequency, while both the HF pump beam and UHF radar beam were directed towards the magnetic zenith (MZ). The HF pump-induced phenomena were diagnosed with several instruments: the bi-static HF radio scatter on the London-Tromsø-St. Petersburg path, the CUTLASS radar in Hankasalmi (Finland), the European Incoherent Scatter (EISCAT) UHF radar at Tromsø and the Tromsø ionosonde (dynasonde). The results show thermal electron excitation of the HF-induced striations seen simultaneously from HF bi-static scatter and CUTLASS radar observations, accompanied by increases of electron temperature when the heater frequency was near and then above the critical frequency of the F2 layer by up to 0.4 MHz. An increase of the electron density up to 25% accompanied by strong HF-induced electron heating was observed, only when the heater frequency was near the critical frequency and just below the third electron gyro harmonic frequency. It is concluded that the combined effect of upper hybrid resonance and gyro resonance at the same altitude gives rise to strong electron heating, the excitation of striations, HF ray trapping and extension of HF waves to altitudes where they can excite Langmuir turbulence and fluxes of electrons accelerated to energies that produce ionization
Multi-wavelength observations of afterglow of GRB 080319B and the modeling constraints
We present observations of the afterglow of GRB 080319B at optical, mm and
radio frequencies from a few hours to 67 days after the burst. Present
observations along with other published multi-wavelength data have been used to
study the light-curves and spectral energy distributions of the burst
afterglow. The nature of this brightest cosmic explosion has been explored
based on the observed properties and it's comparison with the afterglow models.
Our results show that the observed features of the afterglow fits equally good
with the Inter Stellar Matter and the Stellar Wind density profiles of the
circum-burst medium. In case of both density profiles, location of the maximum
synchrotron frequency is below optical and the value of cooling break
frequency is below rays, s after the burst. Also, the
derived value of the Lorentz factor at the time of naked eye brightness is
with the corresponding blast wave size of cm. The
numerical fit to the multi-wavelength afterglow data constraints the values of
physical parameters and the emission mechanism of the burst.Comment: 8 Pages, 3 Figures, Accepted for publication to Astronomy and
Astrophysics on 02/04/200
ASSOCIATIONS BETWEEN DARK TRIAD TRAITS AND MATERIALISTIC VALUE ORIENTATION
The study examines the intensity and relationship of Machiavellianism, narcissism, and psychopathy with orientations toward material values as indicators of success, happiness, and a focus on material well-being in groups with various combinations of Dark Triad traits and a general orientation towards materialism. The relevant indicators were measured in a sample of 442 participants, and groups differed in the intensity of the studied traits and values. As a result, distinctions were established that emphasise the specificity of the link between the Dark Triad’s traits and the orientation toward materialism, as well as their interrelationships. It is conceivable to think that narcissism and psychopathy are the primary characteristics that distinguish the attitude toward material values and reflect various economic tactics.Анализируются различия в выраженности и взаимосвязи макиавеллизма, нарциссизма, психопатии с ориентациями на обладание материальными ценностями как показателями успеха, счастья и центрированность на материальном благополучии в группах с различным сочетанием черт «Темной триады» и общей ориентацией на материализм. На выборке в 442 человека были диагностированы соответствующе показатели и выделены группы, отличающиеся выраженностью исследуемых черт и ценностей. В результате были установлены различия, подчеркивающие специфику соотношения черт «Темной триады» и ориентации на материализм, а также их взаимосвязи. Возможно, что нарциссизм и психопатия являются основными чертами, дифференцирующими отношение к материальным ценностям и представляющие различные стратегии экономического поведения
Wear-Resistant Ultrahigh-Molecular-Weight Polyethylene-Based Nano- and Microcomposites for Implants
The influence of modification by hydroxyapatite (HA) nano- and microparticles on tribotechnical properties of ultrahigh-molecular-weight polyethylene (UHMWPE) was investigated to develop polymer implants for endoprosthesis. It was shown that modification of UHMWPE by hydroxyapatite nanoparticles within range of 0.1–0.5 wt.% results in increase of wear resistance at dry sliding by 3 times. On the other hand adding of 20 wt.% of micron size HA gives rise to the same effect. The effect of increasing wear resistance is not substantially changed at surface treatment of the nano- and microcomposites by N+ ion beams as compared with nonirradiated blends. Preliminary joint mechanical activation of UHMWPE powder and fillers results in more uniform distribution of nanofillers in the matrix and, as a result, formation of more ordered structure. Structure within bulk material and surface layers was studied by means of optical profilometry, scanning electron microscopy, infrared spectroscopy, and differential scanning calorimetry. It is shown that adding of hydroxyapatite nanoparticles and high-energy surface treatment of the composite by N+ ion implantation improve tribotechnical properties of UHMWPE due to formation of chemical bonds in the composite (crosslinking) and ordering of permolecular structure
ДИАГНОСТИКА НАРУШЕНИЙ В СИСТЕМЕ ГЕМОСТАЗА ПРИ ПРИМЕНЕНИИ ВАРФАРИНА У БОЛЬНЫХ КАРДИОХИРУРГИЧЕСКОГО ПРОФИЛЯ
Objective: to reveal early changes in the hemostatic system during warfarin therapy in cardiac surgical patients, by comprehensively evaluating their hemostatic status.Subjects and methods. Seventyfive patients receiving cardiac surgical treatment were examined. All the patients took warfarin for 5±1.5 days. Laboratory studies involving the determination of routine coagulogram readings and thrombodynamic indicators (lag time (Tlag) and rate (Vs) of clot growth, and concentrations of individual Factors II, VI, IX, and X) were used to evaluate the patients' hemostatic status.Results. 28% of the patients were found to have an international normalized ratio (INR) of above 3.0. There was a correlation of Tlag with INR (R2=0.66). Both indicators were comparatively highly correlated with Factor II and Factor X concentrations (R2=0.50 and 0.40 for Tlag; R2=0.53 and 0.48 for INR) and were uncorrelated with Factor IX levels (R2=0.20 for Tlag and 0.34 for INR). However, there was a difference in Factor VII concentrations: no correlation for Tlag (R2=0.20) whereas it for INR was rather high (R2=0.42). The index Vs was uncorrelated with INR (R2=0.24) and the concentration of blood coagulation factors (R2<0.1). There was a high correlation between Factor II and Factor X concentrations (R2=0.87); the correlation between the concentrations of all other pairs of coagulation factors was substantially lower (R20.45). The lack of correlation of a thrombodynamic indicator, such as clot growth rate, with the concentration of coagulation factors points to the fact that warfarin acts mainly on the phase of coagulation activation rather than that of clot propagation.Conclusion. The weak correlation between coagulation factors (except that of a pair of Factor II and Factor X) is indicative of the individual response of the patients to warfarin treatment and the need to monitor the hemostatic status by global hemostatic tests rather than by individual proteins. The thrombodynamic indicator Tlag reflects the effect of warfarin in proportion to INR. Warfarin virtually fails to affect the rate of clot growth so this indicator may be used to evaluate the patient's procoagulant status uncompensated for with warfarin intake. Цель работы. Выявление ранних изменений в системе гемостаза при терапии варфарином у кардиохирургических больных путем комплексной оценки гемостатического статуса пациентов.Материалы и методы. Исследовано 75 пациентов, проходивших кардиохирургическое лечение. Все пациенты получали варфарин (продолжительность лечения больных — 5±1,5 суток). Для оценки гемостатического статуса больных использовали лабораторные методы, включающие определение рутинных показателей коагулограммы, тромбодинамики (время задержки Tlag и скорости роста сгустка (Vs), исследования концентрации II, VII, IX, X факторов).Результаты. Установлено, что у 28%больных показатель МНО находился в области свыше 3.0. Установлена корреляция Tlag с MНО (R2=0,66). Оба показателя имеют сравнительно высокую корреляцию с концентрацией FII и FX (R2=0,50 и 0,40 для Tlag, R2=0,53 и 0,48 для МНО) и не коррелируют с концентрацией FIX (R2=0,20 для Tlag и 0,34 для МНО). Однако наблюдается расхождение в случае концентрации FVII: корреляция для Tlag отсутствует (R2=0,20), тогда как для МНО она достаточно высока (R2=0,42). Параметр Vs не коррелирует с МНО (R2=0,24) и концентрацией факторов свертывания (R2<0,1). Обнаружена высокая корреляция между концентрациями факторов FII и FX (R2=0,87), корреляция между концентрациями всех других пар факторов свертывания существенно ниже (R20,45). Отсутствие корреляции такого показателя тромбодинамики как скорость роста сгустка от концентрации факторов указывает на то, что варфарин действует преимущественно на фазу активации свертывания, но не на фазу распространения сгустка.Заключение. Слабая корреляция факторов свертывания между собой (за исключением пары фактор II — фактор X) указывает на индивидуальный ответ больных на лечение варфарином и необходимость мониторинга состояния гемостаза не по отдельным белкам, а глобальными тестами. Параметр Tlag в тромбодинамике отражает эффект варфарина пропорционально МНО. Варфарин практически не влияет на скорость роста сгустка Vs, поэтому данный параметр можно использовать для оценки прокоагулянтного состояния пациента, не компенсируемого приемом варфарина
Spectroscopic and photoluminescence characterization of Eu 3+-doped monoclinic KY(WO4)2 crystal
Monoclinic 2 at% Eu-doped KY(WO4)2 is grown by top-seeded solution growth method. Polarizationresolved absorption and stimulated-emission cross-section spectra are determined for this crystal. Spectroscopic properties of Eu:KY(WO4)2 are modeled within conventional Judd–Ofelt theory, as well as theory of f–f transition intensities for systems with anomalously strong configuration interaction, yielding absorption oscillator strengths, luminescence branching ratios and radiative lifetime of 5D0 state. The impact of excited-state absorption from this state on possibility of laser operation is discussed. Photoluminescent properties of Eu:KY(WO4)2 are determined. This crystal provides intense red emission with CIE coordinates x¼0.670, y¼0.329
Cognitive and sociocultural aspects of robotized technology: innovative processes of adaptation
The paper dwells upon interaction between socio-cultural phenomena and cognitive characteristics of robotized technology. The interdisciplinary approach was employed in order to cast light on the manifold and multilevel identity of scientific advance in terms of robotized technology within the mental realm. Analyzing robotized technology from the viewpoint of its significance for the modern society is one of the upcoming trends in the contemporary scientific realm. The robots under production are capable of interacting with people; this results in a growing necessity for the studies on social status of robotized technological items. Socio-cultural aspect of cognitive robotized technology is reflected in the fact that the nature becomes 'aware' of itself via human brain, a human being tends to strives for perfection in their intellectual and moral dimensions
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