65 research outputs found
A New Option for a Search for Alpha Variation: Narrow Transitions with Enhanced Sensitivity
We consider several transitions between narrow lines that have an enhanced
sensitivity to a possible variation of the fine structure constant, alpha. This
enhancement may allow a search to be performed with an effective suppression of
the systematic sources of uncertainty that are unavoidable in conventional
high-resolution spectroscopic measurements. In the future this may provide the
strongest laboratory constraints on alpha variation
Optical Clocks in Space
The performance of optical clocks has strongly progressed in recent years,
and accuracies and instabilities of 1 part in 10^18 are expected in the near
future. The operation of optical clocks in space provides new scientific and
technological opportunities. In particular, an earth-orbiting satellite
containing an ensemble of optical clocks would allow a precision measurement of
the gravitational redshift, navigation with improved precision, mapping of the
earth's gravitational potential by relativistic geodesy, and comparisons
between ground clocks.Comment: Proc. III International Conference on Particle and Fundamental
Physics in Space (SpacePart06), Beijing 19 - 21 April 2006, to appear in
Nucl. Phys.
Ultra-precise measurement of optical frequency ratios
We developed a novel technique for frequency measurement and synthesis, based
on the operation of a femtosecond comb generator as transfer oscillator. The
technique can be used to measure frequency ratios of any optical signals
throughout the visible and near-infrared part of the spectrum. Relative
uncertainties of for averaging times of 100 s are possible. Using a
Nd:YAG laser in combination with a nonlinear crystal we measured the frequency
ratio of the second harmonic at 532 nm to the fundamental at
1064 nm, .Comment: 4 pages, 4 figure
Применение янтарной кислоты в процессе фитоэкстракции свинца и кадмия из загрязненных почв
Succinic acid influence on migration properties of lead and cadmium in soil-plant system has been investigated. It has been shown that the addition the activator (succinic acid) into soil increases the efficiency of phytoextraction of lead and cadmium. The optimum conditions of succinic acid usage as the process activator have been established.В работе изучено влияние янтарной кислоты на миграционные свойства свинца и кадмия в системе «почва-рстения». Установлено, что внесение в почву активатора - янтарной кислоты повышает эффективность процесса фитоэкстракции свинца и кадмия. Установлены оптимальные условия применения янтарной кислоты в качестве активатора процесса
Уровень антропогенного воздействия на экосистемы как функция свойств растительных сообществ.
The approach of estimation of a level of anthropogenic impact on ecosystems as a function of properties of plant associations has been proposed. In the course of investigation it was established that it is possible to estimate the growth degree of anthropogenic impact on ecosystem by: the increase part of a ruderal vegetation in common composition of plant associations; the increase amount of a ruderal vegetation growing on one square meter of soil surface (thickness of sowing); the increase of lead and cadmium content in above ground part of the plants. The sufficiently high ability of lead extraction from soil by such plants-accumulators as great nettle and meadow fescue has been establishedПреложен подход к оценке уровня антропогенного воздействия на экосистемы в качестве функции свойств растительных сообществ. В ходе исследования установлено, что об увеличении степени антропогенного воздействия на экосистему можно судить по: увеличению доли рудеральных видов растений в общем составе растительного сообщества; увеличению количества рудеральных растений, произрастаю-щих на одном квадратном метре поверхности (густота стояния); увеличению содержания свинца и кадмия в наземной части растений. Установлена достаточно высокая способность извлечения свинца из почвы такими растениями-аккумуляторами, как крапива двудомная и овсяница луговая
Absolute frequency measurement of the In clock transition with a mode-locked laser
The absolute frequency of the In -
clock transition at 237 nm was measured with an accuracy of 1.8 parts in
. Using a phase-coherent frequency chain, we compared the
- transition with a methane-stabilized He-Ne laser at 3.39 m
which was calibrated against an atomic cesium fountain clock. A frequency gap
of 37 THz at the fourth harmonic of the He-Ne standard was bridged by a
frequency comb generated by a mode-locked femtosecond laser. The frequency of
the In clock transition was found to be
kHz, the accuracy being limited by the uncertainty of the He-Ne laser
reference. This represents an improvement in accuracy of more than 2 orders of
magnitude on previous measurements of the line and now stands as the most
accurate measurement of an optical transition in a single ion.Comment: 3 pages, 2 figures. accepted for publication in Opt. Let
Succinic acid influence on migration properties of lead and cadmium in soil-plant system
Succinic acid influence on migration properties of lead and cadmium in soil-plant system has been investigated. It has been shown that the addition the activator (succinic acid) into soil increases the efficiency of phytoextraction of lead and cadmium. The optimum conditions of succinic acid usage as the process activator have been established
The Level Of Anthropogenic Impact On Ecosystems As A Function Of Properties Of Plant Associations
The approach of estimation of a level of anthropogenic impact on ecosystems as a function of properties of plant associations has been proposed. In the course of investigation it was established that it is possible to estimate the growth degree of anthropogenic impact on ecosystem by: the increase part of a ruderal vegetation in common composition of plant associations; the increase amount of a ruderal vegetation growing on one square meter of soil surface (thickness of sowing); the increase of lead and cadmium content in above ground part of the plants. The sufficiently high ability of lead extraction from soil by such plants-accumulators as great nettle and meadow fescue has been establishe
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