Prediction of GNSS satellite clocks

International Nuclear Information System (INIS)

Broederbauer, V.

2010-01-01

This thesis deals with the characterisation and prediction of GNSS-satellite-clocks. A prerequisite to develop powerful algorithms for the prediction of clock-corrections is the thorough study of the behaviour of the different clock-types of the satellites. In this context the predicted part of the IGU-clock-corrections provided by the Analysis Centers (ACs) of the IGS was compared to the IGS-Rapid-clock solutions to determine reasonable estimates of the quality of already existing well performing predictions. For the shortest investigated interval (three hours) all ACs obtain almost the same accuracy of 0,1 to 0,4 ns. For longer intervals the individual predictions results start to diverge. Thus, for a 12-hours- interval the differences range from nearly 10 ns (GFZ, CODE) until up to some 'tens of ns'. Based on the estimated clock corrections provided via the IGS Rapid products a simple quadratic polynomial turns out to be sufficient to describe the time series of Rubidium-clocks. On the other hand Cesium-clocks show a periodical behaviour (revolution period) with an amplitude of up to 6 ns. A clear correlation between these amplitudes and the Sun elevation angle above the orbital planes can be demonstrated. The variability of the amplitudes is supposed to be caused by temperature-variations affecting the oscillator. To account for this periodical behaviour a quadratic polynomial with an additional sinus-term was finally chosen as prediction model both for the Cesium as well as for the Rubidium clocks. The three polynomial-parameters as well as amplitude and phase shift of the periodic term are estimated within a least-square-adjustment by means of program GNSS-VC/static. Input-data are time series of the observed part of the IGU clock corrections. With the estimated parameters clock-corrections are predicted for various durations. The mean error of the prediction of Rubidium-clock-corrections for an interval of six hours reaches up to 1,5 ns. For the 12-hours

Cesium under pressure: First-principles calculation of the bcc-to-fcc phase transition

Science.gov (United States)

Carlesi, S.; Franchini, A.; Bortolani, V.; Martinelli, S.

1999-05-01

In this paper we present the ab initio calculation of the structural properties of cesium under pressure. The calculation of the total energy is done in the local-density approximation of density-functional theory, using a nonlocal pseudopotential including the nonlinear core corrections proposed by Louie et al. The calculation of the pressure-volume diagram for both bcc and fcc structures allows us to prove that the transition from bcc to fcc structure is a first-order transition.

Helium Pressure Shift of the Hyperfine Clock Transition in Hg-201(+)

Science.gov (United States)

Larigani, S. Taghavi; Burt, E. A.; Tjoelker, R. L.

2010-01-01

There are two stable odd isotopes of mercury with singly ionized hyperfine structure suitable for a microwave atomic clock: Hg-199(+) and Hg-201(+). We are investigating the viability of a trapped ion clock based on Hg-201(+) in a configuration that uses a buffer gas to increase ion loading efficiency and counter ion heating from rf trapping fields. Traditionally, either helium or neon is used as the buffer gas at approx. 10(exp -5) torr to confine mercury ions near room temperature. In addition to the buffer gas, other residual background gasses such as H2O, N2, O2, CO, CO2, and CH2 may be present in trace quantities. Collisions between trapped ions and buffer gas or background gas atoms/molecules produce a momentary shift of the ion clock transition frequency and constitute one of the largest systematic effects in this type of clock. Here we report an initial measurement of the He pressure shift in Hg-201(+) and compare this to Hg-199(+).

Polarizabilities of the beryllium clock transition

International Nuclear Information System (INIS)

Mitroy, J.

2010-01-01

The polarizabilities of the three lowest states of the beryllium atom are determined from a large basis configuration interaction calculation. The polarizabilities of the 2s 2 1 S e ground state (37.73a 0 3 ) and the 2s2p 3 P 0 o metastable state (39.04a 0 3 ) are found to be very similar in size and magnitude. This leads to an anomalously small blackbody radiation shift at 300 K of -0.018(4) Hz for the 2s 2 1 S e -2s2p 3 P 0 o clock transition. Magic wavelengths for simultaneous trapping of the ground and metastable states are also computed.

Colloid stable sorbents for cesium removal: Preparation and application of latex particles functionalized with transition metals ferrocyanides

Energy Technology Data Exchange (ETDEWEB)

Avramenko, Valentin [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation); Bratskaya, Svetlana, E-mail: sbratska@ich.dvo.ru [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation); Zheleznov, Veniamin; Sheveleva, Irina [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation); Voitenko, Oleg [Far Eastern Federal University, Laboratory of Electron Microscopy and Image Processing, 27, Oktyabr' skaya Street, Vladivostok 690950 (Russian Federation); Sergienko, Valentin [Institute of Chemistry, Far Eastern Branch, Russian Academy of Sciences, 159 ave 100-letiya Vladivostoka, Vladivostok 690022 (Russian Federation)

2011-02-28

In this paper we suggest a principally new approach to preparation of colloid stable selective sorbents for cesium uptake using immobilization of transition metals (cobalt, nickel, and copper) ferrocyanides in nanosized carboxylic latex emulsions. The effects of ferrocyanide composition, pH, and media salinity on the sorption properties of the colloid stable sorbents toward cesium ions were studied in solutions containing up to 200 g/L of sodium nitrate or potassium chloride. The sorption capacities of the colloid sorbents based on mixed potassium/transition metals ferrocyanides were in the range 1.3-1.5 mol Cs/mol ferrocyanide with the highest value found for the copper ferrocyanide. It was shown that the obtained colloid-stable sorbents were capable to penetrate through bulk materials without filtration that made them applicable for decontamination of solids, e.g. soils, zeolites, spent ion-exchange resins contaminated with cesium radionuclides. After decontamination of liquid or solid radioactive wastes the colloid-stable sorbents can be easily separated from solutions by precipitation with cationic flocculants providing localization of radionuclides in a small volume of the precipitates formed.

Buckling Transitions and Clock Order of Two-Dimensional Coulomb Crystals

Directory of Open Access Journals (Sweden)

Daniel Podolsky

2016-08-01

Full Text Available Crystals of repulsively interacting ions in planar traps form hexagonal lattices, which undergo a buckling instability towards a multilayer structure as the transverse trap frequency is reduced. Numerical and experimental results indicate that the new structure is composed of three planes, whose separation increases continuously from zero. We study the effects of thermal and quantum fluctuations by mapping this structural instability to the six-state clock model. A prominent implication of this mapping is that at finite temperature, fluctuations split the buckling instability into two thermal transitions, accompanied by the appearance of an intermediate critical phase. This phase is characterized by quasi-long-range order in the spatial tripartite pattern. It is manifested by broadened Bragg peaks at new wave vectors, whose line shape provides a direct measurement of the temperature-dependent exponent η(T characteristic of the power-law correlations in the critical phase. A quantum phase transition is found at the largest value of the critical transverse frequency: Here, the critical intermediate phase shrinks to zero. Moreover, within the ordered phase, we predict a crossover from classical to quantum behavior, signifying the emergence of an additional characteristic scale for clock order. We discuss experimental realizations with trapped ions and polarized dipolar gases, and propose that within accessible technology, such experiments can provide a direct probe of the rich phase diagram of the quantum clock model, not easily observable in condensed matter analogues. Therefore, this work highlights the potential for ionic and dipolar systems to serve as simulators for complex models in statistical mechanics and condensed matter physics.

A Technology Demonstration Experiment for Laser Cooled Atomic Clocks in Space

Science.gov (United States)

Klipstein, W. M.; Kohel, J.; Seidel, D. J.; Thompson, R. J.; Maleki, L.; Gibble, K.

2000-01-01

We have been developing a laser-cooling apparatus for flight on the International Space Station (ISS), with the intention of demonstrating linewidths on the cesium clock transition narrower than can be realized on the ground. GLACE (the Glovebox Laser- cooled Atomic Clock Experiment) is scheduled for launch on Utilization Flight 3 (UF3) in 2002, and will be mounted in one of the ISS Glovebox platforms for an anticipated 2-3 week run. Separate flight definition projects funded at NIST and Yale by the Micro- gravity Research Division of NASA as a part of its Laser Cooling and Atomic Physics (LCAP) program will follow GLACE. Core technologies for these and other LCAP missions are being developed at JPL, with the current emphasis on developing components such as the laser and optics subsystem, and non-magnetic vacuum-compatible mechanical shutters. Significant technical challenges in developing a space qualifiable laser cooling apparatus include reducing the volume, mass, and power requirements, while increasing the ruggedness and reliability in order to both withstand typical launch conditions and achieve several months of unattended operation. This work was performed at the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

Ionization mechanism of cesium plasma produced by irradiation of dye laser

International Nuclear Information System (INIS)

Yamada, Jun; Shibata, Kohji; Uchida, Yoshiyuki; Hioki, Yoshiaki; Sahashi, Toshio.

1992-01-01

When a cesium vapor was irradiated by a dye laser which was tuned to the cesium atomic transition line, the number of charged particles produced by the laser radiation was observed. Several sharp peaks in the number of charged particles were observed, which corresponded to the atomic transition where the lower level was the 6P excited atom. The ionization mechanism of the laser-produced cesium plasma has been discussed. An initial electron is produced by laser absorptions of the cesium dimer. When the cesium density is high, many 6P excited atoms are excited by electron collisions. The 6P excited atom further absorbs the laser photon and is ionized through the higher-energy state. As the cesium vapor pressure increases, the resonance effect becomes observable. The 6P excited atom plays dominant role in the ionization mechanism of the laser-produced cesium plasma. (author)

On mobility of cesium-137, sodium, potassium in various types of soils and prediction of cesium-137 cumulation in agricultural plants

International Nuclear Information System (INIS)

Ashkinazi, Eh.I.

1990-01-01

Mobility of cesium-137, sodium and potassium in the natural environment in podzolic gray and chernozem medium-loamy, sward podzolic sandy soils and chernozem has been studied. Durability of fixation of cesium-137 increases in a number of soils and increase of the level of metabolic potassium. Coefficient of transition of level of metabolic cesium-137 by potassium and sodium, and of sodium by potassium. The mentioned above coefficients can be used for the prediction of cesium-137 cumulation in plants

Structure of cesium loaded iron phosphate glasses: An infrared and Raman spectroscopy study

International Nuclear Information System (INIS)

Joseph, Kitheri; Premila, M.; Amarendra, G.; Govindan Kutty, K.V.; Sundar, C.S.; Vasudeva Rao, P.R.

2012-01-01

The structure of cesium loaded iron phosphate glasses (IPG) was investigated using infrared and Raman spectroscopy. The spectra of the cesium doped samples revealed a structural modification of the parent glass owing to the incorporation of cesium. The structural changes could be correlated with the variation observed in the glass transition temperature of these glasses. Increased Cs-mediated cationic cross linking appears to be the reason for the initial rise in glass transition temperature up to 21 mol% Cs 2 O in IPG; while, breakdown of the phosphate network with increasing cesium content, brings down the glass transition temperature.

Optically pumped semiconductor lasers: Conception and characterization of a single mode source for Cesium atoms manipulation

International Nuclear Information System (INIS)

Cocquelin, B.

2009-02-01

Lasers currently used in atomic clocks or inertial sensors are suffering from a lack of power, narrow linewidth or compactness for future spatial missions. Optically pumped semiconductor lasers, which combine the approach of classical solid state lasers and the engineering of semiconductor laser, are considered here as a candidate to a metrological laser source dedicated to the manipulation of Cesium atoms in these instruments. These lasers have demonstrated high power laser emission in a circular single transverse mode, as well as single longitudinal mode emission, favoured by the semiconductor structure and the external cavity design. We study the definition and the characterization of a proper semiconductor structure for the cooling and the detection of Cesium atoms at 852 nm. A compact and robust prototype tunable on the Cesium D2 hyperfine structure is built. The laser frequency is locked to an atomic transition thanks to a saturated absorption setup. The emission spectral properties are investigated, with a particular attention to the laser frequency noise and the laser linewidth. Finally, we describe and model the thermal properties of the semiconductor structure, which enables the simulation of the laser power characteristic. The experimental parameters are optimised to obtain the maximum output power with our structure. Thanks to our analysis, we propose several ways to overcome these limitations, by reducing the structure heating. (authors)

PHARAO space atomic clock: new developments on the laser source

Science.gov (United States)

Saccoccio, Muriel; Loesel, Jacques; Coatantiec, Claude; Simon, Eric; Laurent, Philippe; Lemonde, Pierre; Maksimovic, I.; Abgrall, M.

2017-11-01

The PHARAO project purpose is to open the way for a new atomic clock generation in space, where laser cooling techniques and microgravity allow high frequency stability and accuracy. The French space agency, CNES is funding and managing the clock construction. The French SYRTE and LKB laboratories are scientific and technical advisers for the clock requirements and the follow-up of subsystem development in industrial companies. EADS SODERN is developing two main subsystems of the PHARAO clock: the Laser Source and the Cesium Tube where atoms are cooled, launched, selected and detected by laser beams. The Laser Source includes an optical bench and electronic devices to generate the laser beams required. This paper describes PHARAO and the role laser beams play in its principle of operation. Then we present the Laser Source design, the technologies involved, and the status of development. Lastly, we focus of a key equipment to reach the performances expected, which is the Extended Cavity Laser Diode.

Egyptian "Star Clocks"

Science.gov (United States)

Symons, Sarah

Diagonal, transit, and Ramesside star clocks are tables of astronomical information occasionally found in ancient Egyptian temples, tombs, and papyri. The tables represent the motions of selected stars (decans and hour stars) throughout the Egyptian civil year. Analysis of star clocks leads to greater understanding of ancient Egyptian constellations, ritual astronomical activities, observational practices, and pharaonic chronology.

Sympathetic cooling in a rubidium cesium mixture: Production of ultracold cesium atoms

International Nuclear Information System (INIS)

Haas, M.

2007-01-01

This thesis presents experiments for the production of ultracold rubidium cesium mixture in a magnetic trap. The long-termed aim of the experiment is the study of the interaction of few cesium atoms with a Bose-Einstein condensate of rubidium atoms. Especially by controlled variation of the cesium atom number the transition in the description of the interaction by concepts of the one-particle physics to the description by concepts of the many-particle physics shall be studied. The rubidium atoms are trapped in a magneto-optical trap (MOT) and from there reloaded into a magnetic trap. In this the rubidium atoms are stored in the state vertical stroke f=2,m f =2 right angle of the electronic ground state and evaporatively cooled by means of microwave-induced transitions into the state vertical stroke f=1,m f =1] (microwave cooling). The cesium atoms are also trppaed in a MOT and into the same magnetic trap reloaded, in which they are stored in the state vertical stroke f=4,m f =4 right angle of the electronic ground state together with rubidium. Because of the different hyperfine splitting only rubidium is evaporatively cooled, while cesium is cooled jointly sympathetically - i.e. by theramal contact via elastic collisions with rubidium atoms. The first two chapters contain a description of interatomic interactions in ultracold gases as well as a short summary of theoretical concepts in the description of Bose-Einstein condensates. The chapters 3 and 4 contain a short presentation of the methods applied in the experiment for the production of ultracold gases as well as the experimental arrangement; especially in the framework of this thesis a new coil system has been designed, which offers in view of future experiments additionally optical access for an optical trap. Additionally the fourth chapter contains an extensive description of the experimental cycle, which is applied in order to store rubidium and cesium atoms together into the magnetic trap. The last chapter

Magnetic circular Dichroism and Faraday rotation of cesium-argon excimers and cesium dimers

International Nuclear Information System (INIS)

Islam, M.A.

1981-01-01

Magnetic Circular Dichroism (MCD) and Faraday Rotation (FR) of excimer absorption bands in gases are measured to obtain the first direct information about the angular momentum quantum numbers and the angular momentum coupling schemes of excimer molecules. So far, there has been no experimental method to obtain information about the axial angular momentum and the angular momentum coupling schemes of excimer molecules. In this experiment, the MCD and the FR of cesium-argon excimer and cesium dimer absorption bands between 5000 A and 10,000 A are measured for the range of temperature from 116 0 to 355 0 C. Of particular interest is the blue wing of D 2 line in cesium which has been the subject of vigorous investigation. The measured MCD data at the blue wing of D 2 line clearly shows that the assignment of 2 μ/sub 1/2/ to this excited state assuming Hund's case (b) is a poor approximation. By a simple inspection of the MCD data, it is found that the coupling scheme is more nearly Hund's case (c) than Hynd's case (b). Several other new and interesting results are obtained. The blue wing associated with 5D transition in atomic cesium is devoid of MCD and exhibits strong MCD in the red wings. Thus, the assignment of 2 μ/sub 1/2/ and 2 π to the blue and red wings, respectively, assuming Hund's case (a) and (b), is a very good approximation. Again the yellow-green band associated with 7s-6s transition in atomic cesium shows no MCD. It is therefore also a good approximation to assign 2 μ/sub 1/2/ to the upper state assuming Hund's case (b). Much more information can be obtained by a detailed analysis of the MCD data

Determination of the thermal radiation effect on an optical strontium lattice clock; Bestimmung des Einflusses thermischer Strahlung auf eine optische Strontium-Gitteruhr

Energy Technology Data Exchange (ETDEWEB)

Middelmann, Thomas

2013-05-31

Optical clocks have the potential to be 100 times more accurate than current best cesium atomic clocks within a fraction of the averaging time. This corresponds to a fractional uncertainty of the clock frequency on the level of 10{sup -18} and requires highaccuracy knowledge of systematic frequency shifts, such that they can be avoided or corrected for. In strontium optical lattice clocks an ensemble of ultracold strontium atoms is confined in an optical lattice, to allow for spectroscopy of the reference transition 5s{sup 2} {sup 1}S{sub 0}-5s5p {sup 3}P{sub 0} in the Lamb-Dicke regime. The by far largest systematic frequency shift of the strontium clock transition is caused by its high sensitivity to blackbody radiation (BBR). The knowledge of the resulting frequency shift limited the achievable clock uncertainty to about 1 x 10{sup -16}. In this thesis for the first time an experimental approach was followed, to determine the sensitivity of the strontium clock transition to blackbody radiation. At an environmental temperature of 300 K the resulting frequency shift corresponds to 2.277 8(23) Hz. The achieved uncertainty contributes with 5 x 10{sup -18} to the fractional systematic uncertainty of the clock frequency. The determination is based on a precision measurement of the difference of static polarizabilities of the two clock states {Delta}{alpha}{sub dc} = {alpha}(5s5p {sup 3}P{sub 0})-{alpha}(5s{sup 2} {sup 1}S{sub 0}) = 4.078 73(11) x 10{sup -39} Cm{sup 2} /V. For this the de Stark shift of the clock transition has been measured in the accurately known electric field of a precision plate capacitor, which has been developed in this work. The attained static polarizability difference {Delta}{alpha}{sub dc} corresponds to the first term of a power series of the sensitivity to BBR. Higher orders are accumulated as dynamic part of the BBR shift. Which has been modelled using {Delta}{alpha}{sub dc} and experimental data for other atomic properties. To

Phase transition in lithium ammonium sulphate doped with cesium metal ions

Science.gov (United States)

Gaafar, M.; Kassem, M. E.; Kandil, S. H.

2000-07-01

Effects of doped cesium (C s+) metal ions (with different molar ratios n) on the phase transition of lithium ammonium sulphate LiNH 4SO 4 system have been studied by measuring the specific heat Cp( T) of the doped systems in the temperature range from 400 to 480 K. The study shows a peculiar phase transition of the pure system ( n=0) characterized by double distinct peaks, changed to a single sharp and narrow one as a result of the doping process. The measurements exhibit different effects of enhanced molar ratios of dopants on the phase transition behaviour of this system. At low dopant content ( n≤3%), the excess specific heat (Δ Cp) max at the transition temperature T1 decreases till a minimum value at n=0.8%, then it increases gradually. In this case, Δ Cp( T) behaviour is varied quantitatively and not modified. Enhanced dopant content ( n>3%) has a pronounced effect on the critical behaviour, which is significantly changed and considerably modified relative to the pure system. In addition, broadening of the critical temperature region, and decrease of (Δ Cp) max associated with changes of the Landau expansion coefficients are obtained and discussed. The study deals with the contribution of the thermally excited dipoles to the specific heat in the ferroelectric region and shows that their energy depends on doping.

A (201)Hg+ Comagnetometer for (199)Hg+ Trapped Ion Space Atomic Clocks

Science.gov (United States)

Burt, Eric A.; Taghavi, Shervin; Tjoelker, Robert L.

2011-01-01

A method has been developed for unambiguously measuring the exact magnetic field experienced by trapped mercury ions contained within an atomic clock intended for space applications. In general, atomic clocks are insensitive to external perturbations that would change the frequency at which the clocks operate. On a space platform, these perturbative effects can be much larger than they would be on the ground, especially in dealing with the magnetic field environment. The solution is to use a different isotope of mercury held within the same trap as the clock isotope. The magnetic field can be very accurately measured with a magnetic-field-sensitive atomic transition in the added isotope. Further, this measurement can be made simultaneously with normal clock operation, thereby not degrading clock performance. Instead of using a conventional magnetometer to measure ambient fields, which would necessarily be placed some distance away from the clock atoms, first order field-sensitive atomic transition frequency changes in the atoms themselves determine the variations in the magnetic field. As a result, all ambiguity over the exact field value experienced by the atoms is removed. Atoms used in atomic clocks always have an atomic transition (often referred to as the clock transition) that is sensitive to magnetic fields only in second order, and usually have one or more transitions that are first-order field sensitive. For operating parameters used in the (199)Hg(+) clock, the latter can be five orders of magnitude or more sensitive to field fluctuations than the clock transition, thereby providing an unambiguous probe of the magnetic field strength.

Compact Optical Atomic Clock Based on a Two-Photon Transition in Rubidium

Science.gov (United States)

Martin, Kyle W.; Phelps, Gretchen; Lemke, Nathan D.; Bigelow, Matthew S.; Stuhl, Benjamin; Wojcik, Michael; Holt, Michael; Coddington, Ian; Bishop, Michael W.; Burke, John H.

2018-01-01

Extralaboratory atomic clocks are necessary for a wide array of applications (e.g., satellite-based navigation and communication). Building upon existing vapor-cell and laser technologies, we describe an optical atomic clock, designed around a simple and manufacturable architecture, that utilizes the 778-nm two-photon transition in rubidium and yields fractional-frequency instabilities of 4 ×10-13/√{τ (s ) } for τ from 1 to 10 000 s. We present a complete stability budget for this system and explore the required conditions under which a fractional-frequency instability of 1 ×10-15 can be maintained on long time scales. We provide a precise characterization of the leading sensitivities to external processes, including magnetic fields and fluctuations of the vapor-cell temperature and 778-nm laser power. The system is constructed primarily from commercially available components, an attractive feature from the standpoint of the commercialization and deployment of optical frequency standards.

Process for recovering cesium from cesium alum

International Nuclear Information System (INIS)

Mein, P.G.

1984-01-01

Cesium is recovered from cesium alum, CsAl(SO 4 ) 2 , by a two-reaction sequence in which the cesium alum is first dissolved in an aqueous hydroxide solution to form cesium alum hydroxide, CsAl(OH) 3 , and potassium sulfate, K 2 SO 4 . Part of the K 2 SO 4 precipitates and is separated from the supernatant solution. In the second reaction, a water-soluble permanganate, such as potassium permanganate, KMnO 4 , is added to the supernatant. This reaction forms a precipitate of cesium permanganate, CsMnO 4 . This precipitate may be separated from the residual solution to obtain cesium permanganate of high purity, which can be sold as a product or converted into other cesium compounds

Dual-Mode Operation of an Optical Lattice Clock Using Strontium and Ytterbium Atoms.

Science.gov (United States)

Akamatsu, Daisuke; Kobayashi, Takumi; Hisai, Yusuke; Tanabe, Takehiko; Hosaka, Kazumoto; Yasuda, Masami; Hong, Feng-Lei

2018-06-01

We have developed an optical lattice clock that can operate in dual modes: a strontium (Sr) clock mode and an ytterbium (Yb) clock mode. Dual-mode operation of the Sr-Yb optical lattice clock is achieved by alternately cooling and trapping 87 Sr and 171 Yb atoms inside the vacuum chamber of the clock. Optical lattices for Sr and Yb atoms were arranged with horizontal and vertical configurations, respectively, resulting in a small distance of the order of between the trapped Sr and Yb atoms. The 1 S 0 - 3 P 0 clock transitions in the trapped atoms were interrogated in turn and the clock lasers were stabilized to the transitions. We demonstrated the frequency ratio measurement of the Sr and Yb clock transitions by using the dual-mode operation of the Sr-Yb optical lattice clock. The dual-mode operation can reduce the uncertainty of the blackbody radiation shift in the frequency ratio measurement, because both Sr and Yb atoms share the same blackbody radiation.

Determination of global positioning system (GPS) receiver clock errors: impact on positioning accuracy

International Nuclear Information System (INIS)

Yeh, Ta-Kang; Hwang, Cheinway; Xu, Guochang; Wang, Chuan-Sheng; Lee, Chien-Chih

2009-01-01

Enhancing the positioning precision is the primary pursuit of global positioning system (GPS) users. To achieve this goal, most studies have focused on the relationship between GPS receiver clock errors and GPS positioning precision. This study utilizes undifferentiated phase data to calculate GPS clock errors and to compare with the frequency of cesium clock directly, to verify estimated clock errors by the method used in this paper. The frequency stability calculated from this paper (the indirect method) and measured from the National Standard Time and Frequency Laboratory (NSTFL) of Taiwan (the direct method) match to 1.5 × 10 −12 (the value from this study was smaller than that from NSTFL), suggesting that the proposed technique has reached a certain level of quality. The built-in quartz clocks in the GPS receivers yield relative frequency offsets that are 3–4 orders higher than those of rubidium clocks. The frequency stability of the quartz clocks is on average two orders worse than that of the rubidium clock. Using the rubidium clock instead of the quartz clock, the horizontal and vertical positioning accuracies were improved by 26–78% (0.6–3.6 mm) and 20–34% (1.3–3.0 mm), respectively, for a short baseline. These improvements are 7–25% (0.3–1.7 mm) and 11% (1.7 mm) for a long baseline. Our experiments show that the frequency stability of the clock, rather than relative frequency offset, is the governing factor of positioning accuracy

Process for recovering cesium from cesium alum

International Nuclear Information System (INIS)

Mein, P.G.

1984-01-01

Cesium is recovered from cesium alum, CsAl(SO 4 ) 2 , by an aqueous conversion and precipitation reaction using a critical stoichiometric excess of a water-soluble permanganate to form solid cesium permanganate (CsMnO 4 ) free from cesium alum. The other metal salts remain in solution, providing the final pH does not cause hydroxides of aluminium or iron to form. The precipitate is separated from the residual solution to obtain CsMnO 4 of high purity

Hg-201 (+) CO-Magnetometer for HG-199(+) Trapped Ion Space Atomic Clocks

Science.gov (United States)

Burt, Eric A. (Inventor); Taghavi, Shervin (Inventor); Tjoelker, Robert L. (Inventor)

2011-01-01

Local magnetic field strength in a trapped ion atomic clock is measured in real time, with high accuracy and without degrading clock performance, and the measurement is used to compensate for ambient magnetic field perturbations. First and second isotopes of an element are co-located within the linear ion trap. The first isotope has a resonant microwave transition between two hyperfine energy states, and the second isotope has a resonant Zeeman transition. Optical sources emit ultraviolet light that optically pump both isotopes. A microwave radiation source simultaneously emits microwave fields resonant with the first isotope's clock transition and the second isotope's Zeeman transition, and an optical detector measures the fluorescence from optically pumping both isotopes. The second isotope's Zeeman transition provides the measure of magnetic field strength, and the measurement is used to compensate the first isotope's clock transition or to adjust the applied C-field to reduce the effects of ambient magnetic field perturbations.

Cesium-plasma-conductivity enhancement in the advanced thermionic energy converter. Final report

International Nuclear Information System (INIS)

Manikopoulos, C.N.

Two methods of plasma conductivity enhancement in a cesium vapor thermionic energy converter have been studied. The first involved resonance photoabsorption of several cesium lines and the second utilized cesium plasma sustenance by application of microwave power. An extensive study of ionization processes in a cesium discharge in the presence of resonance ionization was made. Calculations were made of expected percentage excitation levels for several cesium resonance transitions for different values of neutral density and temperature as well as incident radiation power levels. The results of some of these computations were tabulated. Several ionization schemes were considered. A number of cesium transitions were investigated in the range of 799 to 870 nanometers for four different cesium reservoir temperatures, 467, 511, 550 and 591 K. The related absorption coefficients of the radiation lines in the plasma were deduced and tabulated. The resulting plasma conductivity increase was recorded and the associated ionization enhancement was deduced. A microwave cavity was built where the emitter and collector of a simple thermionic converter made up two of the cavity walls and resonant microwave power was externally applied. The I-V characteristics of the thermionic converter were studied under several microwave power levels in the range of 0 to 2 watts. Significant shifts to higher currents were observed as the microwave power levels were raised. In conclusion, both methods show promise as auxiliary ionization mechanisms for the thermionic energy converter, especially at low emitter temperatures

Active Faraday optical frequency standard.

Science.gov (United States)

Zhuang, Wei; Chen, Jingbiao

2014-11-01

We propose the mechanism of an active Faraday optical clock, and experimentally demonstrate an active Faraday optical frequency standard based on narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standard is determined by the cesium 6 (2)S(1/2) F=4 to 6 (2)P(3/2) F'=4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 281(23) Hz, which is 1.9×10(4) times smaller than the natural linewidth of the cesium 852-nm transition line. The maximum emitted light power reaches 75 μW. The active Faraday optical frequency standard reported here has advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for new generation of optical atomic clocks.

First observation of the strongly forbidden transition 1S0 - 3P0 in Strontium, for an atomic clock with trapped atoms

International Nuclear Information System (INIS)

Courtillot, I.

2003-11-01

This thesis reports the first results towards the realization of an optical clock using trapped strontium atoms. This set up would combine advantages of the different approaches commonly used to develop an atomic frequency standard. The first part describes the cold atoms source which is implemented. A magneto-optical trap operating on the 1 S 0 - 1 P 1 transition at 461 nm is loaded from an atomic beam decelerated by a Zeeman slower. The 461 nm laser is obtained by sum-frequency mixing in a potassium titanyl phosphate (KTP) crystal. The second part is devoted to the different stages developed to achieve the direct excitation of the 1 S 0 - 3 P 0 clock transition in 87 Sr. This line has a theoretical natural width of 10 -3 Hz. Before this detection, we obtained an estimate of the resonance frequency by measuring absolute frequencies of several allowed optical transitions. (author)

Design and Construction of an Atomic Clock on an Atom Chip

International Nuclear Information System (INIS)

Reinhard, Friedemann

2009-01-01

We describe the design and construction of an atomic clock on an atom chip, intended as a secondary standard, with a stability in the range of few 10 -13 at 1 s. This clock is based on a two-photon transition between the hyperfine states |F = 1; m F = -1> and |2; 1> of the electronic ground state of the 87 Rb atom. This transition is interrogated using a Ramsey scheme, operating on either a cloud of thermal atoms or a Bose-Einstein condensate. In contrast to atomic fountain clocks, this clock is magnetically trapped on an atom chip. We describe a theoretical model of the clock stability and the design and construction of a dedicated apparatus. It is able to control the magnetic field at the relative 10 -5 level and features a hybrid atom chip, containing DC conductors as well as a microwave transmission line for the clock interrogation. (author)

Control of the 133 cesium cold collisions, search for a variation of the fine structure constant using a dual rubidium-cesium atomic fountain

International Nuclear Information System (INIS)

Marion, H.

2005-03-01

We developed a method of measurement of the frequency shift due to the collisions between cold atoms. This is the main systematic limitation for the accuracy of the Cs 133 based fountains (∼ 10 -15 in relative frequency). Consequently, we can measure this effect near 0.5% This opens prospects for improvements of the fountains performances in term of accuracy until 10 -16 . The fountain has also obtained a stability about 10 -14 at 1 s. We discovered for the first time, at very low magnetic field (5 ± 1 mG), Feshbach resonances. We also took a new absolute measurement of the hyperfine transition of the Rb 87 , which is the most precise ever carried out and is used now as definition for the secondary standard. By comparing this value with those measured the previous years, we could carry out a test of the stability of the fine structure constant on the level of 10 -15 /yr. We led local comparisons between atomic fountains and the other fountains of the laboratory. Most stable it is unrolled with a combined stability of 5.10 -14 at 1 s. The behavior of the difference of the two clocks goes like white frequency noise up to 3.10 -16 . The assessment of the dual fountain accuracy budget has been evaluated at 7.10 -16 for the cesium part and 8.10 -16 for the rubidium part. We contributed to the realization of the scale of International Atomic Time, by series of calibrations of hydrogen masers. An atomic comparison of fountain by satellite links was tested between our laboratory and our German counterpart. This measurement has determined the good agreement between the two clocks. (author)

A New Trapped Ion Clock Based on Hg-201(+)

Science.gov (United States)

Taghavi-Larigani, S.; Burt, E. A.; Lea, S. N.; Prestage, J. D.; Tjoelker, R. L.

2009-01-01

There are two stable odd isotopes of mercury with singly ionized hyperfine structure suitable for a microwave clock: Hg-199(+) and Hg-201(+). Virtually all trapped mercury ion clocks to date have used the 199 isotope. We have begun to investigate the viability of a trapped ion clock based on Hg-201(+). We have measured the unperturbed frequency of the (S-2)(sub 1/2) F = 1, m(sub F) = 0 to (S-2)(sub 1/2) F = 2, m(sub F) = 0 clock transition to be 29.9543658211(2) GHz. In this paper we describe initial measurements with Hg-201(+) and new applications to clocks and fundamental physics.

A strontium lattice clock with reduced blackbody radiation shift

Energy Technology Data Exchange (ETDEWEB)

Al-Masoudi, Ali Khalas Anfoos

2016-09-30

Optical clocks have been quickly moving to the forefront of the frequency standards field due to their high spectral resolution, and therefore the potential high stability and accuracy. The accuracy and stability of the optical clocks are nowadays two orders of magnitude better than microwave Cs clocks, which realize the SI second. Envisioned applications of highly accurate optical clocks are to perform tests of fundamental physics, for example, searching for temporal drifts of the fine structure constant α, violations of the Local Position Invariance (LPI), dark matter and dark energy, or to performance relativistic geodesy. In this work, the uncertainty of a strontium lattice clock, based on the {sup 1}S{sub 0}-{sup 3}P{sub 0} transition in {sup 87}Sr, due to the blackbody radiation (BBR) shift has been reduced to less than 1 x 10{sup -18} by more than one order of magnitude compared to the previous evaluation of the BBR shift uncertainty in this clock. The BBR shift has been reduced by interrogating the atoms in a cryogenic environment. The systematic uncertainty of the cryogenic lattice clock is evaluated to be 1.3 x 10{sup -17} which is dominated by the uncertainty of the AC Stark shift of the lattice laser and the uncertainty contribution of the BBR shift is negligible. Concerning the instability of the clock, the detection noise of the clock has been measured, and a model linking noise and clock instability has been developed. This noise model shows that, in our lattice clock, quantum projection noise is reached if more than 130 atoms are interrogated. By combining the noise model with the degradation due to the Dick effect reflecting the frequency noise of the interrogation laser, the instability of the clock is estimated to be 1.6 x 10{sup -16}/√(τ/s) in regular operation. During this work, several high-accuracy comparisons to other atomic clocks have been performed, including several absolute frequency measurements. The Sr clock transition frequency

Cesium dihydrophosphate monocrystal growth and certain of their properties

International Nuclear Information System (INIS)

Rashkovich, L.N.; Meteva, K.B.; Shevchik, Ya.Eh.; Goffman, V.G.; Mishchenko, A.V.

1977-01-01

Crystals of cesium dihydrophosphate (centrisymmetrical, monoclinic, point symmetric group 2/m) are obtained by methods involving solvent evaporation and temperature reduction. At -122 deg C, a ferroelectric phase transition occurs, and at 230 and 265 deg C first-kind transitions, which are not accompanied by composition changes. CsH 2 PO 4 solubility substantially increases with higher medium acidity, and remains approximately constant in alkali medium

Sympathetic cooling in a rubidium cesium mixture: Production of ultracold cesium atoms; Sympathetisches Kuehlen in einer Rubidium-Caesium-Mischung: Erzeugung ultrakalter Caesiumatome

Energy Technology Data Exchange (ETDEWEB)

Haas, M.

2007-07-01

This thesis presents experiments for the production of ultracold rubidium cesium mixture in a magnetic trap. The long-termed aim of the experiment is the study of the interaction of few cesium atoms with a Bose-Einstein condensate of rubidium atoms. Especially by controlled variation of the cesium atom number the transition in the description of the interaction by concepts of the one-particle physics to the description by concepts of the many-particle physics shall be studied. The rubidium atoms are trapped in a magneto-optical trap (MOT) and from there reloaded into a magnetic trap. In this the rubidium atoms are stored in the state vertical stroke f=2,m{sub f}=2 right angle of the electronic ground state and evaporatively cooled by means of microwave-induced transitions into the state vertical stroke f=1,m{sub f}=1] (microwave cooling). The cesium atoms are also trppaed in a MOT and into the same magnetic trap reloaded, in which they are stored in the state vertical stroke f=4,m{sub f}=4 right angle of the electronic ground state together with rubidium. Because of the different hyperfine splitting only rubidium is evaporatively cooled, while cesium is cooled jointly sympathetically - i.e. by theramal contact via elastic collisions with rubidium atoms. The first two chapters contain a description of interatomic interactions in ultracold gases as well as a short summary of theoretical concepts in the description of Bose-Einstein condensates. The chapters 3 and 4 contain a short presentation of the methods applied in the experiment for the production of ultracold gases as well as the experimental arrangement; especially in the framework of this thesis a new coil system has been designed, which offers in view of future experiments additionally optical access for an optical trap. Additionally the fourth chapter contains an extensive description of the experimental cycle, which is applied in order to store rubidium and cesium atoms together into the magnetic trap. The

Optical Stabilization of a Microwave Oscillator for Fountain Clock Interrogation.

Science.gov (United States)

Lipphardt, Burghard; Gerginov, Vladislav; Weyers, Stefan

2017-04-01

We describe an optical frequency stabilization scheme of a microwave oscillator that is used for the interrogation of primary cesium fountain clocks. Because of its superior phase noise properties, this scheme, which is based on an ultrastable laser and a femtosecond laser frequency comb, overcomes the frequency instability limitations of fountain clocks given by the previously utilized quartz-oscillator-based frequency synthesis. The presented scheme combines the transfer of the short-term frequency instability of an optical cavity and the long-term frequency instability of a hydrogen maser to the microwave oscillator and is designed to provide continuous long-term operation for extended measurement periods of several weeks. The utilization of the twofold stabilization scheme on the one hand ensures the referencing of the fountain frequency to the hydrogen maser frequency and on the other hand results in a phase noise level of the fountain interrogation signal, which enables fountain frequency instabilities at the 2.5 ×10 -14 (τ/s) -1/2 level that are quantum projection noise limited.

Studies on synthesis of some composites and their uses for cesium separation

International Nuclear Information System (INIS)

Someda, H.H.; El-Zahhar, A.A.; Shehata, M.K.K.; El-Naggar, H.A.

2002-01-01

In this study some composite sorbents were prepared by supporting hexacyanoferrate complexes of some transition metals like Co, Ni, Fe and Zn on some different solid supports e.g. cellulose and other natural materials as wood powder. These composites were used for cesium sorption and showed that the highest sorption capacity is for zinc composite and the lowest is for cobalt composite. Also the factors affecting the sorption capacity like acid concentration, competing ions and cesium ion concentration were studied. The release of the sorbed cesium from the composite materials was also studied under different concentrations of different solutions like sodium nitrate, silver nitrate, ammonium nitrate and a mixture of ammonium nitrate and silver nitrate solutions

Performance of a 229Thorium solid-state nuclear clock

International Nuclear Information System (INIS)

Kazakov, G A; Schreitl, M; Winkler, G; Schumm, T; Litvinov, A N; Romanenko, V I; Yatsenko, L P; Romanenko, A V

2012-01-01

The 7.8 eV nuclear isomer transition in 229 thorium has been suggested as a clock transition in a new type of optical frequency standard. Here we discuss the construction of a ‘solid-state nuclear clock’ from thorium nuclei implanted into single crystals transparent in the vacuum ultraviolet range. We investigate crystal-induced line shifts and broadening effects for the specific system of calcium fluoride. At liquid nitrogen temperatures, the clock performance will be limited by decoherence due to magnetic coupling of the thorium nuclei to neighboring nuclear moments, ruling out the commonly used Rabi or Ramsey interrogation schemes. We propose clock stabilization based on a fluorescence spectroscopy method and present optimized operation parameters. Taking advantage of the large number of quantum oscillators under continuous interrogation, a fractional instability level of 10 −19 might be reached within the solid-state approach. (paper)

Process for recovering cesium from pollucite

International Nuclear Information System (INIS)

Mein, P.G.

1985-01-01

Cesium is recovered from a cesium-bearing mineral such as pollucite by extraction with hydrochloric acid to obtain an extract of cesium chloride and other alkali metal and polyvalent metal chlorides. The iron and aluminum chlorides can be precipitated as the hydroxides and separated from the solution of the alkali metal chlorides to which is added potassium permanganate or other water-soluble permanganate to selectively precipitate cesium permanganate. The cesium precipitate is then separated from the residual solution containing the metal chlorides. The cesium permanganate, which is in a very pure form, can be converted to other cesium compounds by reaction with a reducing agent to obtain cesium carbonate and cesium delta manganese dioxide

Studies on the synthesis and characterization of cesium-containing iron phosphate glasses

Science.gov (United States)

Joseph, Kitheri; Govindan Kutty, K. V.; Chandramohan, P.; Vasudeva Rao, P. R.

2009-02-01

Isotopes of cesium and strontium can be utilized as radiation source for various industrial and medical applications after their separation from high level nuclear waste. However, these elements need to be immobilized in a suitable matrix. In the present work, a systematic approach has been made to immobilize inactive cesium into iron phosphate glass. Up to 36 mol% of Cs 2O has been loaded successfully without crystallization. The glass transition temperature of the cesium loaded glass was found to increase initially and then decrease as a function of Cs 2O content. Mössbauer studies show that the concentration of Fe 3+ ions in the cesium loaded glasses is >95%. Volatilization experiments at 1263 K show that the weight loss is >0.5% for a period of 4 h. The 36 mol% of Cs 2O loaded iron phosphate glass with high Fe 3+ content described in this paper is reported for the first time.

Innovation and reliability of atomic standards for PTTI applications

Science.gov (United States)

Kern, R.

1981-01-01

Innovation and reliability in hyperfine frequency standards and clock systems are discussed. Hyperfine standards are defined as those precision frequency sources and clocks which use a hyperfine atomic transition for frequency control and which have realized significant commercial production and acceptance (cesium, hydrogen, and rubidium atoms). References to other systems such as thallium and ammonia are excluded since these atomic standards have not been commercially exploited in this country.

Optical lattice clock with Strontium atoms

International Nuclear Information System (INIS)

Baillard, X.

2008-01-01

This thesis presents the latest achievements regarding the optical lattice clock with Strontium atoms developed at LNE-SYRTE. After a review of the different types of optical clocks that are currently under development, we stress on the concept of optical lattice clock which was first imagined for Sr 87 using the 1 S 0 → 3 P 0 transition. We exhibit the features of this atom, in particular the concept of magic wavelength for the trap, and the achievable performances for this kind of clock. The second part presents the experimental aspects, insisting particularly on the ultra-stable laser used for the interrogation of the atoms which is a central part of the experiment. Among the latest improvements, an optical pumping phase and an interrogation phase using a magnetic field have been added in order to refine the evaluation of the Zeeman effect. Finally, the last part presents the experimental results. The last evaluation of the clock using Sr 87 atoms allowed us to reach a frequency accuracy of 2.6*10 -15 and a measurement in agreement with the one made at JILA (Tokyo university) at the 10 -15 level. On another hand, thanks to recent theoretical proposals, we made a measurement using the bosonic isotope Sr 88 by adapting the experimental setup. This measurement represents the first evaluation for this type of clock, with a frequency accuracy of 7*10 -14 . (author)

Simultaneous Faraday filtering of the Mollow triplet sidebands with the Cs-D1 clock transition.

Science.gov (United States)

Portalupi, Simone Luca; Widmann, Matthias; Nawrath, Cornelius; Jetter, Michael; Michler, Peter; Wrachtrup, Jörg; Gerhardt, Ilja

2016-11-25

Hybrid quantum systems integrating semiconductor quantum dots (QDs) and atomic vapours become important building blocks for scalable quantum networks due to the complementary strengths of individual parts. QDs provide on-demand single-photon emission with near-unity indistinguishability comprising unprecedented brightness-while atomic vapour systems provide ultra-precise frequency standards and promise long coherence times for the storage of qubits. Spectral filtering is one of the key components for the successful link between QD photons and atoms. Here we present a tailored Faraday anomalous dispersion optical filter based on the caesium-D 1 transition for interfacing it with a resonantly pumped QD. The presented Faraday filter enables a narrow-bandwidth (Δω=2π × 1 GHz) simultaneous filtering of both Mollow triplet sidebands. This result opens the way to use QDs as sources of single as well as cascaded photons in photonic quantum networks aligned to the primary frequency standard of the caesium clock transition.

Methods of producing cesium-131

Science.gov (United States)

Meikrantz, David H; Snyder, John R

2012-09-18

Methods of producing cesium-131. The method comprises dissolving at least one non-irradiated barium source in water or a nitric acid solution to produce a barium target solution. The barium target solution is irradiated with neutron radiation to produce cesium-131, which is removed from the barium target solution. The cesium-131 is complexed with a calixarene compound to separate the cesium-131 from the barium target solution. A liquid:liquid extraction device or extraction column is used to separate the cesium-131 from the barium target solution.

Development of an atomic clock on an atom chip: Optimisation of the coherence time and preliminary characterisation

International Nuclear Information System (INIS)

Lacroute, Clement

2010-01-01

We describe the construction and preliminary characterization of an atomic clock on an atom chip. A sample of magnetically trapped 87 Rb atoms is cooled below 1 μK, close to Bose- Einstein condensation temperature. The trapped states |F = 1; m F = -1> and |F = 2;m F = 1> define our two-photon clock transition. Atoms are trapped around a field B0 = 3.23 G, where the clock frequency is first-order insensitive to magnetic field fluctuations. We have designed an atom chip that includes a microwave coplanar waveguide which drives the 6.835 GHz transition. The whole clock cycle is performed in the vicinity of the chip surface, making the physics package compact (5 cm) 3 . We first describe the experimental setup of the clock, and the optical bench that has been developed and characterized during this thesis. We then give the results obtained for atom cooling, which led to obtaining a 3 10 4 atoms Bose-Einstein condensate. We finally present the results obtained by Ramsey spectroscopy of the clock transition. We measure coherence times exceeding 10 seconds with our setup, dominated by atom losses. A preliminary measurement shows that the clock relative frequency stability is of 6 10 -12 at 1 s, limited by technical noise. Our goal is to reach a stability in the low 10 -13 at 1 s, i.e. better than commercial clocks and competitive with today's best compact clocks. (author)

Performance demonstration of a single-frequency optically-pumped cesium beam frequency standard for space applications

Science.gov (United States)

Lecomte, S.; Haldimann, M.; Ruffieux, R.; Thomann, P.; Berthoud, P.

2017-11-01

Observatoire de Neuchâtel (ON) is developing a compact optically-pumped cesium beam frequency standard in the frame of an ESA-ARTES 5 project. The simplest optical scheme, which is based on a single optical frequency for both preparation and detection processes of atoms, has been chosen to fulfill reliability constraints of space applications. With our laboratory demonstrator operated at 852 nm (D2 line), we have measured a frequency stability of σy=2.74x10-12 τ -1/2, which is compliant with the Galileo requirement. The atomic resonator is fully compliant to be operated with a single diode laser at 894 nm (D1 line). Sensitivity measurements of the clock signal to the microwave power and to the optical pumping power are also presented. Present performance limitations are discussed and further improvements are proposed in order to reach our ultimate frequency stability goal of σy=1x10-12 τ -1/2. The clock driving software is also briefly described.

Systematic evaluation of a 171Yb optical clock by synchronous comparison between two lattice systems.

Science.gov (United States)

Gao, Qi; Zhou, Min; Han, Chengyin; Li, Shangyan; Zhang, Shuang; Yao, Yuan; Li, Bo; Qiao, Hao; Ai, Di; Lou, Ge; Zhang, Mengya; Jiang, Yanyi; Bi, Zhiyi; Ma, Longsheng; Xu, Xinye

2018-05-22

Optical clocks are the most precise measurement devices. Here we experimentally characterize one such clock based on the 1 S 0 - 3 P 0 transition of neutral 171 Yb atoms confined in an optical lattice. Given that the systematic evaluation using an interleaved stabilization scheme is unable to avoid noise from the clock laser, synchronous comparisons against a second 171 Yb lattice system were implemented to accelerate the evaluation. The fractional instability of one clock falls below 4 × 10 -17 after an averaging over a time of 5,000 seconds. The systematic frequency shifts were corrected with a total uncertainty of 1.7 × 10 -16 . The lattice polarizability shift currently contributes the largest source. This work paves the way to measuring the absolute clock transition frequency relative to the primary Cs standard or against the International System of Units (SI) second.

Cesium reservoir and interconnective components

International Nuclear Information System (INIS)

1994-03-01

The program objective is to demonstrate the technology readiness of a TFE (thermionic fuel element) suitable for use as the basic element in a thermionic reactor with electric power output in the 0.5 to 5.0 MW range. A thermionic converter must be supplied with cesium vapor for two reasons. Cesium atoms adsorbed on the surface of the emitter cause a reduction of the emitter work function to permit high current densities without excessive heating of the emitter. The second purpose of the cesium vapor is to provide space-charge neutralization in the emitter-collector gap so that the high current densities may flow across the gap unattenuated. The function of the cesium reservoir is to provide a source of cesium atoms, and to provide a reserve in the event that cesium is lost from the plasma by any mechanism. This can be done with a liquid cesium metal reservoir in which case it is heated to the desired temperature with auxiliary heaters. In a TFE, however, it is desirable to have the reservoir passively heated by the nuclear fuel. In this case, the reservoir must operate at a temperature intermediate between the emitter and the collector, ruling out the use of liquid reservoirs. Integral reservoirs contained within the TFE will produce cesium vapor pressures in the desired range at typical electrode temperatures. The reservoir material that appears to be the best able to meet requirements is graphite. Cesium intercalates easily into graphite, and the cesium pressure is insensitive to loading for a given intercalation stage. The goals of the cesium reservoir test program were to verify the performance of Cs-graphite reservoirs in the temperature-pressure range of interest to TFE operation, and to test the operation of these reservoirs after exposure to a fast neutron fluence corresponding to seven year mission lifetime. In addition, other materials were evaluated for possible use in the integral reservoir

Cesium-137 in ash from combustion of biofuels. Application of regulations from the Swedish Radiation Safety Authority; Cesium-137 i aska fraan foerbraenning av biobraenslen. Tillaempning av Straalsaekerhetsmyndighetens regler

Energy Technology Data Exchange (ETDEWEB)

Sjoeblom, Rolf (Tekedo AB, Nykoeping (SE))

2009-03-19

. The differences are large. The transitions between Cesium/Potassium in the pore water and in the exchangeable positions are rapid. Other transitions are slow. Over the course of a few years, Cesium becomes bonded as non-exchangeable and after a few decades, the content of non-exchangeable and mineral Cesium may be comparable in magnitude. The migration rate depends on the availability. Before Cesium-137 in fallout becomes absorbed, it is transported with the water, and this is the reason for the initial rapid penetration into soil on the order of a decimeter. When most of the Cesium-137 has become non-exchangeable and mineral, the migration rate may be as low as on the order of a millimetre per year. There is an interesting finding to report about clay. For short term migration, i e shortly after a fallout, clay provides a retention that is far superior to that of sand. This is probably related to the fact that clay contains many more positions for ion exchange as compared to sand. After some time when most of the Cesium appears in non-exchangeable and mineral positions, clay and sand are comparable. It might be tempting to assume that organic soils would provide a good retention since they can absorb nutrients from artificial fertilizers and keep them available to plants. Measurements have shown, however, that Cesium-137 may migrate rapidly in soils that lack a mineral component, e g soils consisting of peat. This can be assumed to relate to the fact that the bonding to the many exchangeable positions is much weaker as compared to those in non-exchangeable and in mineral positions. The data on ash are scarce. The data found indicate that the availability of Cesium-137 is high in fresh ash, but that the bonding is remarkably strong already after a few years. It cannot be taken for granted without further information that fresh water conditions apply also when the salt content in the pore water is high. Investigations have shown, however, that the solid mineral phase

Mineral resource of the month: cesium

Science.gov (United States)

Angulo, Marc A.

2010-01-01

The article offers information on cesium, a golden alkali metal derived from the Latin word caesium which means bluish gray. It mentions that cesium is the first element discovered with the use of spectroscopy. It adds that the leading producer and supplier of cesium is Canada and there are 50,000 kilograms of cesium consumed of the world in a year. Moreover, it states that only 85% of the cesium formate can be retrieved and recycled.

Cesium in the nutrient cycle. Cesium metsaen ravinnekierrossa marjojen ja sienten cesium ei vaehene

Energy Technology Data Exchange (ETDEWEB)

Rantavaara, A

1992-01-01

Most radioactive cesium in forests is deposited in soil, from which it passes into berries and mushrooms, and further to game. The cesium contents of Finnish berries and mushrooms vary depending on the intensity of Chernobyl fallout. Northern Haeme, Pirkanmaa and parts of central Finland received the most fallout. Weather conditions and the environmental factors, and other circumstances during the growth period, also affect the contents. However, consumption of wild berries, mushrooms and game need not be restricted because of radioactivity anywhere in Finland.

Lego clocks: building a clock from parts.

Science.gov (United States)

Brunner, Michael; Simons, Mirre J P; Merrow, Martha

2008-06-01

A new finding opens up speculation that the molecular mechanism of circadian clocks in Synechococcus elongatus is composed of multiple oscillator systems (Kitayama and colleagues, this issue, pp. 1513-1521), as has been described in many eukaryotic clock model systems. However, an alternative intepretation is that the pacemaker mechanism-as previously suggested-lies primarily in the rate of ATP hydrolysis by the clock protein KaiC.

Regulation of circadian clock transcriptional output by CLOCK:BMAL1

Science.gov (United States)

Trott, Alexandra J.

2018-01-01

The mammalian circadian clock relies on the transcription factor CLOCK:BMAL1 to coordinate the rhythmic expression of 15% of the transcriptome and control the daily regulation of biological functions. The recent characterization of CLOCK:BMAL1 cistrome revealed that although CLOCK:BMAL1 binds synchronously to all of its target genes, its transcriptional output is highly heterogeneous. By performing a meta-analysis of several independent genome-wide datasets, we found that the binding of other transcription factors at CLOCK:BMAL1 enhancers likely contribute to the heterogeneity of CLOCK:BMAL1 transcriptional output. While CLOCK:BMAL1 rhythmic DNA binding promotes rhythmic nucleosome removal, it is not sufficient to generate transcriptionally active enhancers as assessed by H3K27ac signal, RNA Polymerase II recruitment, and eRNA expression. Instead, the transcriptional activity of CLOCK:BMAL1 enhancers appears to rely on the activity of ubiquitously expressed transcription factors, and not tissue-specific transcription factors, recruited at nearby binding sites. The contribution of other transcription factors is exemplified by how fasting, which effects several transcription factors but not CLOCK:BMAL1, either decreases or increases the amplitude of many rhythmically expressed CLOCK:BMAL1 target genes. Together, our analysis suggests that CLOCK:BMAL1 promotes a transcriptionally permissive chromatin landscape that primes its target genes for transcription activation rather than directly activating transcription, and provides a new framework to explain how environmental or pathological conditions can reprogram the rhythmic expression of clock-controlled genes. PMID:29300726

Low-power, miniature {sup 171}Yb ion clock using an ultra-small vacuum package

Energy Technology Data Exchange (ETDEWEB)

Jau, Y.-Y.; Schwindt, P. D. D. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Partner, H. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Center for Quantum Information and Control (CQuIC), Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Prestage, J. D.; Kellogg, J. R.; Yu, N. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

2012-12-17

We report a demonstration of a very small microwave atomic clock using the 12.6 GHz hyperfine transition of the trapped {sup 171}Yb ions inside a miniature, completely sealed-off 3 cm{sup 3} ion-trap vacuum package. In the ion clock system, all of the components are highly miniaturized with low power consumption except the 369 nm optical pumping laser still under development for miniaturization. The entire clock, including the control electronics, consumes <300 mW. The fractional frequency instability of the miniature Yb{sup +} clock reaches the 10{sup -14} range after a few days of integration.

Cesium transport data for HTGR systems

International Nuclear Information System (INIS)

Myers, B.F.; Bell, W.E.

1979-09-01

Cesium transport data on the release of cesium from HTGR fuel elements are reviewed and discussed. The data available through 1976 are treated. Equations, parameters, and associated variances describing the data are presented. The equations and parameters are in forms suitable for use in computer codes used to calculate the release of metallic fission products from HTGR fuel elements into the primary circuit. The data cover the following processes: (1) diffusion of cesium in fuel kernels and pyrocarbon, (2) sorption of cesium on fuel rod matrix material and on graphite, and (3) migration of cesium in graphite. The data are being confirmed and extended through work in progress

Extraction of radioactive cesium from tea leaves

International Nuclear Information System (INIS)

Yano, Yukiko; Kubo, M. Kenya; Higaki, Shogo; Hirota, Masahiro; Nomura, Kiyoshi

2011-01-01

Radioactive contamination of foodstuffs attributed to the Fukushima Daiichi nuclear disaster has become a social problem. This study investigated the extraction of radioactive cesium from the contaminated leaves to the tea. The green tea was brewed twice reusing the same leaves to study the difference in extraction of cesium between the first and second brew. Moreover, the extraction of cesium was studied in correlation to brewing time. The concentration of radioactive cesium was determined with gamma spectrometry, and the concentration of caffeine was determined with absorption spectrometry. About 40% of cesium was extracted from leaves in the first brew, and about 80% was extracted in the second brew. The extraction of cesium increased over time, and it reached about 80% after 10 minutes brew. The ratio of radioactive cesium to caffeine decreased linearly over time. This study revealed that the extraction of cesium was higher for the second brew, and a rapid increase in extraction was seen as the tea was brewed for 6 minutes and more. Therefore, the first brew of green tea, which was brewed within 5 minutes, contained the least extraction of radioactive cesium from the contaminated leaves. (author)

Relativistic Ideal Clock

OpenAIRE

Bratek, Łukasz

2015-01-01

Two particularly simple ideal clocks exhibiting intrinsic circular motion with the speed of light and opposite spin alignment are described. The clocks are singled out by singularities of an inverse Legendre transformation for relativistic rotators of which mass and spin are fixed parameters. Such clocks work always the same way, no matter how they move. When subject to high accelerations or falling in strong gravitational fields of black holes, the clocks could be used to test the clock hypo...

Process for cesium decontamination and immobilization

Science.gov (United States)

Komarneni, Sridhar; Roy, Rustum

1989-01-01

Cesium can be selectively recovered from a nuclear waste solution containing cesium together with other metal ions by contact with a modified phlogopite which is a hydrated, sodium phlogopite mica. Once the cesium has entered the modified phlogopite it is fixed and can be safely stored for long periods of time.

Decorporation of cesium-137; Decorporation du cesium-137

Energy Technology Data Exchange (ETDEWEB)

Le Fleche, Ph; Destombe, C; Grasseau, A; Mathieu, J; Chancerelle, Y; Mestries, J C [GMR, Direction des Recherches, Etudes et Techniques, 94 - Arcueil (France)

1998-12-31

Cesium radio-isotopes, especially cesium-137 ({sup 137}Cs) are among the radionuclides of main importance produced by a fission reaction in reactor or a nuclear weapon explosion. In the environment, {sup 137}Cs is a major contaminant which can cause severe {beta}, {gamma}irradiations and contaminations. {sup 137}Cs is distributed widely and relatively uniformly throughout the body with the highest concentration in skeletal muscles. A treatment becomes difficult afterwards. The purposes of this report are Firstly to compare the Prussian blue verses cobalt and potassium ferrocyanide (D.I. blue) efficiency for the {sup 137}Cs decorporation and secondly to assess a chronological treatment with D.I. blue. (author)

Decorporation of cesium-137; Decorporation du cesium-137

Energy Technology Data Exchange (ETDEWEB)

Le Fleche, Ph.; Destombe, C.; Grasseau, A.; Mathieu, J.; Chancerelle, Y.; Mestries, J.C. [GMR, Direction des Recherches, Etudes et Techniques, 94 - Arcueil (France)

1997-12-31

Cesium radio-isotopes, especially cesium-137 ({sup 137}Cs) are among the radionuclides of main importance produced by a fission reaction in reactor or a nuclear weapon explosion. In the environment, {sup 137}Cs is a major contaminant which can cause severe {beta}, {gamma}irradiations and contaminations. {sup 137}Cs is distributed widely and relatively uniformly throughout the body with the highest concentration in skeletal muscles. A treatment becomes difficult afterwards. The purposes of this report are Firstly to compare the Prussian blue verses cobalt and potassium ferrocyanide (D.I. blue) efficiency for the {sup 137}Cs decorporation and secondly to assess a chronological treatment with D.I. blue. (author)

Process for cesium decontamination and immobilization

Science.gov (United States)

Komarneni, S.; Roy, R.

1988-04-25

Cesium can be selectively recovered from a nuclear waste solution containing cesium together with other metal ions by contact with a modified phlogopite which is a hydrated, sodium phlogopite mica. Once the cesium has entered the modified phlogopite it is fixed and can be safely stored for long periods of time. 6 figs., 2 tabs.

Method for primary containment of cesium wastes

International Nuclear Information System (INIS)

Angelini, P.; Arnold, W.D.; Blanco, R.E.; Bond, W.D.; Lackey, W.J.; Stinton, D.P.

1983-01-01

A method for producing a cesium-retentive waste form, characterized by a high degree of compositional stability and mechanical integrity, is provided by subjecting a cesium-loaded zeolite to heat under conditions suitable for stabilizing the zeolite and immobilizing the cesium, and coating said zeolite for sufficient duration within a suitable environment with at least one dense layer of pyrolytic carbon to seal therein said cesium to produce a final, cesium-bearing waste form. Typically, the zeolite is stabilized and the cesium immobilized in less than four hours by confinement within an air environment maintained at about 600 0 C. Coatings are thereafter applied by confining the calcined zeolite within a coating environment comprising inert fluidizing and carbon donor gases maintained at 1,000* C. For a suitable duration

Management of cesium loaded AMP- Part I preparation of 137Cesium concentrate and cementation of secondary wastes

International Nuclear Information System (INIS)

Singh, I.J.; Sathi Sasidharan, N.; Yalmali, Vrunda S.; Deshingkar, D.S.; Wattal, P.K.

2005-11-01

Separation of 137 cesium from High Level Waste can be achieved by use of composite-AMP, an engineered form of Ammonium Molybdo-Phosphate(AMP). Direct vitrification of cesium loaded composite AMP in borosilicate glass matrix leads to separation of water soluble molybdate phase. A proposed process describes two different routes of selective separation of molybdates and phosphate to obtain solutions of cesium concentrates. Elution of 137 Cesium from composite-AMP by decomposing it under flow conditions using saturated barium hydroxide was investigated. This method leaves molybdate and phosphate embedded in the column but only 70% of total cesium loaded on column could be eluted. Alternatively composite-AMP was dissolved in sodium hydroxide and precipitation of barium molybdate-phosphate from the resultant solution, using barium nitrate was investigated by batch methods. The precipitation technique gave over 99.9% of 137 Cesium activity in solutions, free of molybdates and phosphates, which is ideally suited for immobilization in borosilicate glass matrix. Detailed studies were carried out to immobilize secondary waste of 137 Cesium contaminated barium molybdate-phosphate precipitates in the slag cement matrix using vermiculite and bentonite as admixtures. The cumulative fraction of 137 Cs leached from the cement matrix blocks was 0.05 in 140 days while the 137 Cs leach rate was 0.001 gm/cm 2 /d. (author)

Gauge systems and functions, hermitian operators and clocks as conjugate functions for the constraints

International Nuclear Information System (INIS)

Cuesta, Vladimir; Vergara, Jose David; Montesinos, Merced

2011-01-01

We work with gauge systems and using gauge invariant functions we study its quantum counterpart and we find if all these operators are self adjoint or not. Our study is divided in two cases, when we choose clock or clocks that its Poisson brackets with the set of constraints is one or it is different to one. We show some transition amplitudes.

Cesium Concentration in MCU Solvent

International Nuclear Information System (INIS)

Walker, D

2006-01-01

During Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) operations, Cs-137 concentrations in product streams will vary depending on the location in the process and on the recent process conditions. Calculations of cesium concentrations under a variety of operating conditions reveal the following: (1) Under nominal operations with salt solution feed containing 1.1 Ci Cs-137 per gallon, the maximum Cs-137 concentration in the process will occur in the strip effluent (SE) and equal 15-16.5 Ci/gal. (2) Under these conditions, the majority of the solvent will contain 0.005 to 0.01 Ci/gal, with a limited portion of the solvent in the contactor stages containing ∼4 Ci/gal. (3) When operating conditions yield product near 0.1 Ci Cs-137/gal in the decontaminated salt solution (DSS), the SE cesium concentration will be the same or lower than in nominal operations, but majority of the stripped solvent will increase to ∼2-3 Ci/gal. (4) Deviations in strip and waste stream flow rates cause the largest variations in cesium content: (a) If strip flow rates deviate by -30% of nominal, the SE will contain ∼23 Ci/gal, although the cesium content of the solvent will increase to only 0.03 Ci/gal; (b) If strip flow rate deviates by -77% (i.e., 23% of nominal), the SE will contain 54 Ci/gal and solvent will contain 1.65 Ci/gal. At this point, the product DSS will just reach the limit of 0.1 Ci/gal, causing the DSS gamma monitors to alarm; and (c) Moderate (+10 to +30%) deviations in waste flow rate cause approximately proportional increases in the SE and solvent cesium concentrations. Recovery from a process failure due to poor cesium stripping can achieve any low cesium concentration required. Passing the solvent back through the contactors while recycling DSS product will produce a ∼70% reduction during one pass through the contactors (assuming the stripping D value is no worse than 0.36). If the solvent is returned to the solvent hold tank (containing additional

Thermal properties of cesium molybdate

International Nuclear Information System (INIS)

Minato, Kazuo; Fukuda, Kousaku; Takano, Masahide; Sato, Seichi; Ohashi, Hiroshi

1996-01-01

Cesium is one of the most important fission products to aid in the understanding and prediction of the behavior of oxide nuclear fuels because of its high mobility, chemical reactivity, and large yield. In postirradiation examinations of the Phoenix reactor fuel pins, the accumulation of cesium and molybdenum between the fuel pellet and cladding was observed, though the chemical form was not determined. In the thermodynamic analyses of chemical states of fission products, Cs 2 MoO 4 was often predicted to exist as a stable compound in oxide fuels. The Cs 2 MoO 4 compound is thermodynamically stable under the conditions of light water reactors, fast breeder reactors, and high-temperature gas-cooled reactors. In the Cs-Mo-O system several phases have been found, and the structural and thermodynamic properties were studied. At room temperature, Cs 2 MoO 4 has an orthorhombic structure and a phase transition occurs at 841 K to a hexagonal structure. Both structures are expected to exist in the fuel, depending on the fuel temperature. However, no data has been available on the thermal properties of CS 2 MoO 4 . In the current work, the thermal expansion and thermal conductivity of Cs 2 MoO 4 were determined, which are the basic data needed to understand and predict the fuel/clad mechanical interaction and fuel temperature

Cesium removal and kinetics equilibrium: Precipitation kinetics

International Nuclear Information System (INIS)

Barnes, M.J.

1999-01-01

This task consisted of both non-radioactive and radioactive (tracer) tests examining the influence of potentially significant variables on cesium tetraphenylborate precipitation kinetics. The work investigated the time required to reach cesium decontamination and the conditions that affect the cesium precipitation kinetics

Radiochemical determination of cesium-137 in seawater

International Nuclear Information System (INIS)

Cunha, I.I.L.; Munita, C.S.; Paiva, R.P.

1990-01-01

Seawater samples were collected from the Atlantic Ocean, in the vicinity of Ubatuba (Sao Paulo State - Brazil), acidified to pH 1 and stored in polyethylene containers. Cesium was precipitated with ammonium phospho molybdate (AMP), synthesized in our laboratory. The elements potassium and rubidium present in the seawater are also coprecipitated by AMP and adequate decontamination of the cesium is made by preparing a column by mixing Cs-137 AMP precipitate and asbestos. The interfering elements were eluted with 1.0 M ammonium nitrate solution whereas cesium was eluted with 1.0 M sodium hydroxide solution. Cesium was reprecipitated by acidifying the solution with concentrated hydrochloric acid. The overall chemical yield of cesium was of 75%. (author)

Crown bridged thiacalix[4]arenes as cesium-selective ionophores in solvent polymeric membrane electrodes

International Nuclear Information System (INIS)

Bereczki, Robert; Csokai, Viktor; Gruen, Alajos; Bitter, Istvan; Toth, Klara

2006-01-01

Novel 1,3-alternate thiacalix[4]mono- and biscrown-6 ethers were studied as ionophores in poly(vinyl chloride) membrane electrodes. Their selectivity behavior was characterized with respect to large number of cations, including potential interferents in environmental samples, and the membrane composition was optimized for cesium ion response. Among the ionophores, 1,3-alternate thiacalix[4]mono(crown-6) ether showed, especially high selectivity for cesium over other alkali-metal ions. Transition and heavy metal ions did not interfere seriously with the electrode response, which indicates that the bridging sulfur atoms do not take part in the ion recognition process. The potentiometric cesium responses of all electrodes involved in this study were found close to Nernstian and the detection limits were lower than 10 -7 M. The Cs + /Na + selectivity of the different ionophore-based sensors and the solvent extraction ability of the ligands were interpreted based on the respective constants of complex formation

Effect of decontamination of planting soil using zeolite slurry that inhibits transition of radioactive cesium from soil to plant bodies

International Nuclear Information System (INIS)

Ikeda, Yutaka; Akita, Hiroyuki; Kikawada, Kazuya

2013-01-01

The accident of Fukushima Daiichi nuclear energy plant by the tsunami resulting from the Great Eastern Japan Earthquake in 2011 caused the radiation contamination of cultivated field in Fukushima Prefecture. Some decontamination techniques such as surface soil grab, deep cultivation, and adding zeolite to the soil were tested in the rice fields of Fukushima Prefecture. Zeolite is usually used in the form of particle. It inhibits the transition of radioactive cesium from soil to plant bodies. Here, zeolite slurry was also used. The inhibition effect of the zeolite slurry was checked not only in the field but also in a laboratory experiment using some vegetables. The laboratory test results proved the effect of decontamination for vegetable; however, the field test showed uncertainness owing to the low passage coefficient of rice. (author)

Cesium migration in LMFBR fuel pins

International Nuclear Information System (INIS)

Karnesky, R.A.; Jost, J.W.; Stone, I.Z.

1978-10-01

The factors affecting the axial migration of cesium in mixed oxide fuel pins and the effects of cesium migration on fuel pin performance are examined. The development and application of a correlated model which will predict the occurrence of cesium migration in a mixed oxide (75 w/o UO 2 + 25 w/o PuO 2 ) fuel pins over a wide range of fabrication and irradiation conditions are described

Cesium ion bombardment of metal surfaces

International Nuclear Information System (INIS)

Tompa, G.S.

1986-01-01

The steady state cesium coverage due to cesium ion bombardment of molybdenum and tungsten was studied for the incident energy range below 500 eV. When a sample is exposed to a positive ion beam, the work function decreases until steady state is reached with a total dose of less than ≅10 16 ions/cm 2 , for both tungsten and molybdenum. A steady state minimum work function surface is produced at an incident energy of ≅100 eV for molybdenum and at an incident energy of ≅45 eV for tungsten. Increasing the incident energy results in an increase in the work function corresponding to a decrease in the surface coverage of cesium. At incident energies less than that giving the minimum work function, the work function approaches that of cesium metal. At a given bombarding energy the cesium coverage of tungsten is uniformly less than that of molybdenum. Effects of hydrogen gas coadsorption were also examined. Hydrogen coadsorption does not have a large effect on the steady state work functions. The largest shifts in the work function due to the coadsorption of hydrogen occur on the samples when there is no cesium present. A theory describing the steady-state coverage was developed is used to make predictions for other materials. A simple sticking and sputtering relationship, not including implantation, cannot account for the steady state coverage. At low concentrations, cesium coverage of a target is proportional to the ratio of (1 - β)/γ where β is the reflection coefficient and γ is the sputter yield. High coverages are produced on molybdenum due to implantation and low backscattering, because molybdenum is lighter than cesium. For tungsten the high backscattering and low implantation result in low coverages

Cesium levels in foodstuffs fall slowly

International Nuclear Information System (INIS)

Rantavaara, A.

1994-01-01

Since spring 1986, radioactive decay has reduced the total amount of radioactive cesium 137 in the Finnish environment, originating in Chernobyl, by 17 per cent. The cesium content in fish keeps falling at a diminishing rate, depending on the species of fish and environmental factors. The use of fish from lakes need not be restricted anymore. The cesium contents of game, mushrooms and wild berries have remained steady for some years now. The same is true for agricultural produce. The contents in milk and meat still keep falling slowly. Most of the cesium ingested by finns comes from fish, then from game, reindeer and gathered foods; the lowest amounts are received from agricultural products. (orig.)

High Precision Clock Bias Prediction Model in Clock Synchronization System

Directory of Open Access Journals (Sweden)

Zan Liu

2016-01-01

Full Text Available Time synchronization is a fundamental requirement for many services provided by a distributed system. Clock calibration through the time signal is the usual way to realize the synchronization among the clocks used in the distributed system. The interference to time signal transmission or equipment failures may bring about failure to synchronize the time. To solve this problem, a clock bias prediction module is paralleled in the clock calibration system. And for improving the precision of clock bias prediction, the first-order grey model with one variable (GM(1,1 model is proposed. In the traditional GM(1,1 model, the combination of parameters determined by least squares criterion is not optimal; therefore, the particle swarm optimization (PSO is used to optimize GM(1,1 model. At the same time, in order to avoid PSO getting stuck at local optimization and improve its efficiency, the mechanisms that double subgroups and nonlinear decreasing inertia weight are proposed. In order to test the precision of the improved model, we design clock calibration experiments, where time signal is transferred via radio and wired channel, respectively. The improved model is built on the basis of clock bias acquired in the experiments. The results show that the improved model is superior to other models both in precision and in stability. The precision of improved model increased by 66.4%~76.7%.

Studies on release and deposition behaviour of cesium from contaminated sodium pools and cesium trap development for FBTR

International Nuclear Information System (INIS)

Sahoo, P.; Kannan, S.E.; Muralidharan, P.; Chandran, K.

1996-01-01

Investigations were carried out on the release and deposition behaviour of cesium from sodium pools in air-filled chamber in the temperature range of 673 to 873 K, using Cs-134 to simulate Cs-137. About 0.12 kg of sodium was loaded in a burn-pot together with 92.5 kBq of cesium. Experiments were carried out with 21% oxygen. Natural burning period of sodium and specific activity ratio between cesium and sodium showed a tendency to decrease and release fractions of both the species tended to increase with temperature. From the surface deposited aerosols it was observed that cesium has propensity to settle down closer to the point of release. A cesium trap has been developed for FBTR with RVC as getter material. Absorption kinetics and particle release behaviour studies pointed to its intended satisfactory performance in the plant. (author)

Behavior of ion-implanted cesium in silicon dioxide films

International Nuclear Information System (INIS)

Fishbein, B.J.

1988-01-01

Charged impurities in silicon dioxide can be used to controllably shift the flatband voltage of metal-oxide-semiconductor devices independently of the substrate doping, the gate oxide thickness and the gate-electrode work function. Cesium is particularly well suited for this purpose because it is immobile in SiO 2 at normal device operating temperatures, and because it can be controllably introduced into oxide films by ion implantation. Cesium is positively charged in silicon dioxide, resulting in a negative flatband voltage shift. Possible applications for cesium technology include solar cells, devices operated at liquid nitrogen temperature, and power devices. The goal of this work has been to characterize as many aspects of cesium behavior in silicon dioxide as are required for practical applications. Accordingly, cesium-ion implantation, cesium diffusion, and cesium electrical activation in SiO 2 were studied over a broad range of processing conditions. The electrical properties of cesium-containing oxides, including current-voltage characteristics, interface trap density, and inversion-layer carrier mobility were examined, and several potential applications for cesium technology have been experimentally demonstrated

Cesium diffusion in Bure mud-rock: effect of cesium sorption and of the surface structure of the clay

International Nuclear Information System (INIS)

Melkior, T.; Motellier, S.; Yahiaoui, S.

2005-01-01

Full text of publication follows: This work is devoted to cesium diffusion through mud-rock samples from Bure (Meuse/Haute- Marne, France). This rock is mainly composed of interstratified illite/smectite, quartz and calcite. According to published data, positively charged solutes exhibit high diffusion coefficients in argillaceous media compared to neutral species. This effect was actually observed for cesium in Bure mud-rock samples: the effective diffusion coefficients (De) of tritiated water and cesium were found to be ca. 2 x 10 -11 m 2 s -1 and 2.5 x 10 -10 m 2 s -1 , respectively. Some authors assign this 'enhanced diffusion' of cations to the particular migration of ions within the electrical double layer, next to mineral surfaces (surface diffusion mechanism). To assess the role of sorbed ions in the diffusive transfer, cesium diffusion coefficients in Bure mud-rock were measured at different cesium concentrations. The distribution coefficient of cesium onto Bure mud-rock was measured in batch: it significantly varies over the concentration range investigated in the diffusion tests (between 2 x 10 -6 M and 2 x 10 -2 M). If sorbed ions contribute to the transfer, the effective diffusion coefficients deduced from these different tests should depend on cesium concentration. Nevertheless, the measured effective diffusion coefficients are found to be relatively unaffected by cesium concentration. It is thus concluded that ions at the sorbed state play a minor role in the diffusion. Following the assumption of an 'accelerated' transfer due to ions located in the diffuse double layer, the charge of the clay particles should affect the 'enhanced diffusion' of cesium. Therefore, a mud-rock sample was first crushed and contacted with a cationic surfactant at different solid/liquid ratios. The conditions were adjusted to obtain suspensions having positive, neutral and negative zeta potentials respectively. Three compact samples were then made with these different

''Crown molecules'' for separating cesium

International Nuclear Information System (INIS)

Dozol, J.F.; Lamare, V.

2002-01-01

After the minor actinides, the second category of radionuclides that must be isolated to optimize nuclear waste management concerns fission products, especially two cesium isotopes. If the cesium-135 isotope could be extracted, it could subsequently be transmuted or conditioned using a tailor-made process. Eliminating the 137 isotope from reprocessing and nuclear facility-dismantling waste would allow to dispose of most of this waste in near-surface facilities, and simply process the small remaining quantity containing long-lived elements. CEA research teams and their international partners have thought up crown molecules that could be used to pick out the cesium and meet these objectives. (authors)

On the cesium-rich part of the Cs-Te phase diagram

International Nuclear Information System (INIS)

Boer, R. de; Cordfunke, E.H.P.

1995-03-01

The cesium-tellurium system in the region between 33 and 55 at.% Te has been investigated with X-ray diffraction and DSC. The existence of the compounds Cs 5 Te 3 and CsTe is demonstrated. The latter compound exhibits a structural transition at elevated temperature, as does the compound Cs 2 Te. The earlier reported compounds Cs 3 Te 2 and Cs 5 Te 4 do not exist. (orig.)

A combined cesium-strontium extraction/recovery process

International Nuclear Information System (INIS)

Horwitz, E.P.; Dietz, M.L.; Jensen, M.P.

1996-01-01

A new solvent extraction process for the simultaneous extraction of cesium and strontium from acidic nitrate media is described. This process uses a solvent formulation comprised of 0.05 M di-t-butylcyclohexano-18-crown-6 (DtBuCH18C6), 0.1 M Crown 100' (a proprietary, cesium-selective derivative of dibenzo-18-crown-6), 1.2 M tributyl phosphate (TBP), and 5% (v/v) lauryl nitrile in an isoparaffinic hydrocarbon diluent. Distribution ratios for cesium and strontium from 4 M nitric acid are 4.13 and 3.46, respectively. A benchtop batch countercurrent extraction experiment indicates that >98% of the cesium and strontium initially present in the feed solution can be removed in only four extraction stages. Through proper choice of extraction and strip conditions, extracted cesium and strontium can be recovered either together or individually

Clock Drawing in Spatial Neglect: A Comprehensive Analysis of Clock Perimeter, Placement, and Accuracy

Science.gov (United States)

Chen, Peii; Goedert, Kelly M.

2012-01-01

Clock drawings produced by right-brain-damaged (RBD) individuals with spatial neglect often contain an abundance of empty space on the left while numbers and hands are placed on the right. However, the clock perimeter is rarely compromised in neglect patients’ drawings. By analyzing clock drawings produced by 71 RBD and 40 healthy adults, this study investigated whether the geometric characteristics of the clock perimeter reveal novel insights to understanding spatial neglect. Neglect participants drew smaller clocks than either healthy or non-neglect RBD participants. While healthy participants’ clock perimeter was close to circular, RBD participants drew radially extended ellipses. The mechanisms for these phenomena were investigated by examining the relation between clock-drawing characteristics and performance on six subtests of the Behavioral Inattention Test (BIT). The findings indicated that the clock shape was independent of any BIT subtest or the drawing placement on the test sheet and that the clock size was significantly predicted by one BIT subtest: the poorer the figure and shape copying, the smaller the clock perimeter. Further analyses revealed that in all participants, clocks decreased in size as they were placed farther from the center of the paper. However, even when neglect participants placed their clocks towards the center of the page, they were smaller than those produced by healthy or non-neglect RBD participants. These results suggest a neglect-specific reduction in the subjectively available workspace for graphic production from memory, consistent with the hypothesis that neglect patients are impaired in the ability to enlarge the attentional aperture. PMID:22390278

Uptake behavior of titanium molybdophosphate for cesium and strontium

International Nuclear Information System (INIS)

Yavari, R.; Ahmadi, S.J.; Huang, Y.D.

2010-01-01

This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at 25 deg C using column packed with H 3 O + form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed out of column by using 4 M NH 4 Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially cesium from nuclear waste solution. (author)

A GPS Satellite Clock Offset Prediction Method Based on Fitting Clock Offset Rates Data

Directory of Open Access Journals (Sweden)

WANG Fuhong

2016-12-01

Full Text Available It is proposed that a satellite atomic clock offset prediction method based on fitting and modeling clock offset rates data. This method builds quadratic model or linear model combined with periodic terms to fit the time series of clock offset rates, and computes the model coefficients of trend with the best estimation. The clock offset precisely estimated at the initial prediction epoch is directly adopted to calculate the model coefficient of constant. The clock offsets in the rapid ephemeris (IGR provided by IGS are used as modeling data sets to perform certain experiments for different types of GPS satellite clocks. The results show that the clock prediction accuracies of the proposed method for 3, 6, 12 and 24 h achieve 0.43, 0.58, 0.90 and 1.47 ns respectively, which outperform the traditional prediction method based on fitting original clock offsets by 69.3%, 61.8%, 50.5% and 37.2%. Compared with the IGU real-time clock products provided by IGS, the prediction accuracies of the new method have improved about 15.7%, 23.7%, 27.4% and 34.4% respectively.

Separation of cesium and strontium with zeolites

Energy Technology Data Exchange (ETDEWEB)

Kanno, T; Hashimoto, H [Tohoku Univ., Sendai (Japan). Research Inst. of Mineral Dressing and Metallurgy

1976-06-01

The basic studies of separation of cesium and strontium were made with specimens of zeolite, which are synthetic zeolites A, X and Y; synthetic mordenite; natural mordenite; and clinoptilolite. Ammonium chloride was used as eluent, because it was considered to be a most appropriate eluent in alkaline chlorides. Cesium was easily eluted from the zeolites A and X by ammonium chloride solution, but it was difficult to elute from the synthetic mordenite, natural mordenite and clinoptilolite by ammonium chloride solution, but it was difficult to elute from the zeolites A and X. The zeolite Y is the only one zeolite among these zeolites from which both of cesium and strontium were easily eluted by ammonium chloride solution. Strontium could be separated from cesium with zeolites by formation of Sr-EDTA chelate at pH above 11. In this process, cesium was only exchanged in zeolite column, but strontium flow out from it.

Separation of cesium and strontium with zeolites

International Nuclear Information System (INIS)

Kanno, Takuji; Hashimoto, Hiroyuki

1976-01-01

The basic studies of separation of cesium and strontium were made with specimens of zeolite, which are synthetic zeolites A, X and Y; synthetic mordenite; natural mordenite; and clinoptilolite. Ammonium chloride was used as eluent, because it was considered to be a most appropriate eluent in alkaline chlorides. Cesium was easily eluted from the zeolites A and X by ammonium chloride solution, but it was difficult to elute from the synthetic mordenite, natural mordenite and clinoptilolite by ammonium chloride solution, but it was difficult to elute from the zeolites A and X. The zeolite Y is the only one zeolite among these zeolites from which both of cesium and strontium were easily eluted by ammonium chloride solution. Strontium could be separated from cesium with zeolites by formation of Sr-EDTA chelate at pH above 11. In this process, cesium was only exchanged in zeolite column, but strontium flow out from it. (auth.)

Quality assurance program plan for cesium legacy project

International Nuclear Information System (INIS)

Tanke, J.M.

1997-01-01

This Quality Assurance Program Plan (QAPP) provides information on how the Quality Assurance Program is implemented for the Cesium Legacy Project. It applies to those items and tasks which affect the completion of activities identified in the work breakdown structure of the Project Management Plan (PMP). These activities include all aspects of cask transportation, project related operations within the 324 Building, and waste management as it relates to the specific activities of this project. General facility activities (i.e. 324 Building Operations, Central Waste Complex Operations, etc.) are covered in other appropriate QAPPs. The 324 Building is currently transitioning from being a Pacific Northwest National Laboratory (PNNL) managed facility to a B and W Hanford Company (BWHC) managed facility. During this transition process existing PNNL procedures and documents will be utilized until replaced by BWHC procedures and documents

Cesium heat-pipe thermostat

Energy Technology Data Exchange (ETDEWEB)

Wu, F.; Song, D.; Sheng, K.; Wu, J. [Changcheng Institute of Metrology and Measurement, 100095, Beijing (China); Yi, X. [China National South Aviation industry CO., LTD., 412002, Hunan (China); Yu, Z. [Dalian Jinzhou Institute of Measurement and Testing, 116100, Liaoning (China)

2013-09-11

In this paper the authors report a newly developed Cesium Heat-Pipe Thermostat (Cs HPT) with the operation range of 400 °C to 800 °C. The working medium is cesium (Cs) of 99.98% purity and contains no radioisotope. A Cs filing device is developed which can prevent Cs being in contact with air. The structural material is stainless steel. A 5000 h test has been made to confirm the compatibility between cesium and stainless steel. The Cs HPT has several thermometer wells of 220mm depth with different diameters for different sizes of thermometers. The temperature uniformity of the Cs HPT is 0.06 °C to 0.20 °C. A precise temperature controller is used to ensure the temperature fluctuation within ±0.03 °C. The size of Cs HPT is 380mm×320mm×280mm with foot wheels for easy moving. The thermostat has been successfully used for the calibration of industrial platinum resistance thermometers and thermocouples.

Cesium Salts of Phosphotungstic Acid: Comparison of Surface ...

African Journals Online (AJOL)

NICO

acidity and lowest solubility in reaction media in comparison with the other cesium content salts. KEYWORDS. Polyoxometalates, cesium ... insoluble salt of HPA is cesium salt of tungstophosphoric acid,. CsxH3-xPW12O40 (CsxPW), a ... of Cs2CO3, very fine particles (precipitates) were formed to make the solution milky.

Method of processing radioactive cesium liquid wastes

International Nuclear Information System (INIS)

Nishijima, Hiroaki; Asaoka, Sachio; Kondo, Tadami; Suzuki, Isao.

1985-01-01

Purpose: To convert and settle cesium, mainly, Cs-137 in liquid wastes in the form of pollucites, that is, cesium-containing ores. Constitution: Water, silica, alumina and alkali metal source are mixed with radioactive liquid wastes containing cesium as the main metal element ingredient, to which an onium compound is further added and they are brought into reaction till pollucite ores (Cs 16 (Al 16 Si 32 O 96 )) are formed. Since most portion of cesium is thus settled in the form of pollucites, storage safety can be attained. Further, the addition of the onium compound can moderate the condition and shorten the time till the pollucite ores are formed. The onium compound usable herein includes tetramethyl ammonium. (Kamimura, M.)

Effects of mass defect in atomic clocks

Science.gov (United States)

Taichenachev, A. V.; Yudin, V. I.

2018-01-01

We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (such as gravitational and quadratic Doppler shifts) can be interpreted as consequences of the mass defect, i.e., without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions..

Optically trapped atom interferometry using the clock transition of large 87Rb Bose-Einstein condensates

International Nuclear Information System (INIS)

Altin, P A; McDonald, G; Doering, D; Debs, J E; Barter, T H; Close, J D; Robins, N P; Haine, S A; Hanna, T M; Anderson, R P

2011-01-01

We present a Ramsey-type atom interferometer operating with an optically trapped sample of 10 6 Bose-condensed 87 Rb atoms. We investigate this interferometer experimentally and theoretically with an eye to the construction of future high precision atomic sensors. Our results indicate that, with further experimental refinements, it will be possible to produce and measure the output of a sub-shot-noise-limited, large atom number BEC-based interferometer. The optical trap allows us to couple the |F=1, m F =0)→|F=2, m F =0) clock states using a single photon 6.8 GHz microwave transition, while state selective readout is achieved with absorption imaging. We analyse the process of absorption imaging and show that it is possible to observe atom number variance directly, with a signal-to-noise ratio ten times better than the atomic projection noise limit on 10 6 condensate atoms. We discuss the technical and fundamental noise sources that limit our current system, and present theoretical and experimental results on interferometer contrast, de-phasing and miscibility.

Evaluation of electrochemical ion exchange for cesium elution

International Nuclear Information System (INIS)

Bontha, J.D.; Kurath, D.E.; Surma, J.E.; Buehler, M.F.

1996-04-01

Electrochemical elution was investigated as an alternative method to acid elution for the desorption of cesium from loaded ion exchange resins. The approach was found to have several potential advantages over existing technologies, in particular, electrochemical elution eliminates the need for addition of chemicals to elute cesium from the ion exchange resin. Also, since, in the electrochemical elution process the eluting solution is not in direct contact with the ion exchange material, very small volumes of the eluting solution can be used in a complete recycle mode in order to minimize the total volume of the cesium elute. In addition, the cesium is eluted as an alkaline solution that does not require neutralization with caustic to meet the tank farm specifications. Other advantages include easy incorporation of the electrochemical elution process into the present cesium recovery schemes

Physiological links of circadian clock and biological clock of aging.

Science.gov (United States)

Liu, Fang; Chang, Hung-Chun

2017-07-01

Circadian rhythms orchestrate biochemical and physiological processes in living organisms to respond the day/night cycle. In mammals, nearly all cells hold self-sustained circadian clocks meanwhile couple the intrinsic rhythms to systemic changes in a hierarchical manner. The suprachiasmatic nucleus (SCN) of the hypothalamus functions as the master pacemaker to initiate daily synchronization according to the photoperiod, in turn determines the phase of peripheral cellular clocks through a variety of signaling relays, including endocrine rhythms and metabolic cycles. With aging, circadian desynchrony occurs at the expense of peripheral metabolic pathologies and central neurodegenerative disorders with sleep symptoms, and genetic ablation of circadian genes in model organisms resembled the aging-related features. Notably, a number of studies have linked longevity nutrient sensing pathways in modulating circadian clocks. Therapeutic strategies that bridge the nutrient sensing pathways and circadian clock might be rational designs to defy aging.

Seasonal variation of cesium 134 and cesium 137 in semidomestic reindeer in Norway after the Chernobyl accident

International Nuclear Information System (INIS)

Eikelmann, I.M.H.; Bye, K.; Sletten, H.D.

1990-01-01

The Chernobyl accident had a great impact on the semidomestic reindeer husbandry in central Norway. Seasonal differences in habitat and diet resulted in large variations in observed radiocesium concentrations in reindeer after the Chernobyl accident. In three areas with high values of cesium-134 and cesium-137 in lichens, the main feed for reindeer in winter, reindeer were sampled every second month to monitor the seasonal variation and the decrease rate of the radioactivity. The results are based on measurements of cesium-134 and cesium-137 content in meat and blood and by whole-body monitoring of live animals. In 1987 the increase of radiocesium content in reindeer in Vågå were 4x from August to January. The mean reductions in radiocesium content from the winter 1986/87 to the winter 1987/88 were 32%, 50% and 43% in the areas of Vågå, Østre-Namdal and Lom respectively

Mass defect effects in atomic clocks

Science.gov (United States)

Yudin, Valeriy; Taichenachev, Alexey

2018-03-01

We consider some implications of the mass defect on the frequency of atomic transitions. We have found that some well-known frequency shifts (the gravitational shift and motion-induced shifts such as quadratic Doppler and micromotion shifts) can be interpreted as consequences of the mass defect in quantum atomic physics, i.e. without the need for the concept of time dilation used in special and general relativity theories. Moreover, we show that the inclusion of the mass defect leads to previously unknown shifts for clocks based on trapped ions.

Adsorption of cesium on cement mortar from aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Volchek, Konstantin, E-mail: konstantin.volchek@ec.gc.ca [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Miah, Muhammed Yusuf [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Department of Applied Chemistry and Chemical Technology, Noakhali Science and Technology University (Bangladesh); Kuang, Wenxing; DeMaleki, Zack [Emergencies Science and Technology Section, Environment Canada, 335 River Road, Ottawa, Ontario, Canada K1A 0H3 (Canada); Tezel, F. Handan [Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis-Pasteur, Ottawa, Ontario, Canada K1N 6N5 (Canada)

2011-10-30

Highlights: {yields} The adsorption of cesium on cement mortar was investigated in a range of temperatures and cesium concentrations. {yields} The pseudo-second order kinetic model produced a good fit with the experimental kinetic data. {yields} Equilibrium test results correlated well with the Freundlich isotherm adsorption model. {yields} The interaction between cesium ions and cement mortar was dominated by chemical adsorption. - Abstract: The adsorption of cesium on cement mortar from aqueous solutions was studied in series of bench-scale tests. The effects of cesium concentration, temperature and contact time on process kinetics and equilibrium were evaluated. Experiments were carried out in a range of initial cesium concentrations from 0.0103 to 10.88 mg L{sup -1} and temperatures from 278 to 313 K using coupons of cement mortar immersed in the solutions. Non-radioactive cesium chloride was used as a surrogate of the radioactive {sup 137}Cs. Solution samples were taken after set periods of time and analyzed by inductively coupled plasma mass spectroscopy. Depending on the initial cesium concentration, its equilibrium concentration in solution ranged from 0.0069 to 8.837 mg L{sup -1} while the respective surface concentration on coupons varied from 0.0395 to 22.34 {mu}g cm{sup -2}. Equilibrium test results correlated well with the Freundlich isotherm model for the entire test duration. Test results revealed that an increase in temperature resulted in an increase in adsorption rate and a decrease in equilibrium cesium surface concentration. Among several kinetic models considered, the pseudo-second order reaction model was found to be the best to describe the kinetic test results in the studied range of concentrations. The adsorption activation energy determined from Arrhenius equation was found to be approximately 55.9 kJ mol{sup -1} suggesting that chemisorption was the prevalent mechanism of interaction between cesium ions and cement mortar.

Entanglement of quantum clocks through gravity.

Science.gov (United States)

Castro Ruiz, Esteban; Giacomini, Flaminia; Brukner, Časlav

2017-03-21

In general relativity, the picture of space-time assigns an ideal clock to each world line. Being ideal, gravitational effects due to these clocks are ignored and the flow of time according to one clock is not affected by the presence of clocks along nearby world lines. However, if time is defined operationally, as a pointer position of a physical clock that obeys the principles of general relativity and quantum mechanics, such a picture is, at most, a convenient fiction. Specifically, we show that the general relativistic mass-energy equivalence implies gravitational interaction between the clocks, whereas the quantum mechanical superposition of energy eigenstates leads to a nonfixed metric background. Based only on the assumption that both principles hold in this situation, we show that the clocks necessarily get entangled through time dilation effect, which eventually leads to a loss of coherence of a single clock. Hence, the time as measured by a single clock is not well defined. However, the general relativistic notion of time is recovered in the classical limit of clocks.

Application of Cesium isotopes in daily life

International Nuclear Information System (INIS)

Jordao, B.O.; Quaresma, D.S.; Carvalho, R.J.; Peixoto, J.G.P.

2014-01-01

In the world of science, the desire of the scientific community to discover new chemical elements is crucial for the development of new technologies in various fields of knowledge. And the main chemical element addressed by this article is Cesium, but specifically 133 Cesium isotope and radioisotope 137 Cesium, exemplifying their physical and chemical characteristics, and their applications. This article will also show how these isotopes have provided researchers a breakthrough in the field of radiological medicine and in time and frequency metrology. (author)

Phase locking and multiple oscillating attractors for the coupled mammalian clock and cell cycle.

Science.gov (United States)

Feillet, Céline; Krusche, Peter; Tamanini, Filippo; Janssens, Roel C; Downey, Mike J; Martin, Patrick; Teboul, Michèle; Saito, Shoko; Lévi, Francis A; Bretschneider, Till; van der Horst, Gijsbertus T J; Delaunay, Franck; Rand, David A

2014-07-08

Daily synchronous rhythms of cell division at the tissue or organism level are observed in many species and suggest that the circadian clock and cell cycle oscillators are coupled. For mammals, despite known mechanistic interactions, the effect of such coupling on clock and cell cycle progression, and hence its biological relevance, is not understood. In particular, we do not know how the temporal organization of cell division at the single-cell level produces this daily rhythm at the tissue level. Here we use multispectral imaging of single live cells, computational methods, and mathematical modeling to address this question in proliferating mouse fibroblasts. We show that in unsynchronized cells the cell cycle and circadian clock robustly phase lock each other in a 1:1 fashion so that in an expanding cell population the two oscillators oscillate in a synchronized way with a common frequency. Dexamethasone-induced synchronization reveals additional clock states. As well as the low-period phase-locked state there are distinct coexisting states with a significantly higher period clock. Cells transition to these states after dexamethasone synchronization. The temporal coordination of cell division by phase locking to the clock at a single-cell level has significant implications because disordered circadian function is increasingly being linked to the pathogenesis of many diseases, including cancer.

First observation of the strongly forbidden transition {sup 1}S{sub 0} - {sup 3}P{sub 0} in Strontium, for an atomic clock with trapped atoms; Premiere observation de la transition fortement interdite {sup 1}S{sub 0} - {sup 3}P{sub 0} du strontium, pour une horloge optique a atomes pieges

Energy Technology Data Exchange (ETDEWEB)

Courtillot, I

2003-11-01

This thesis reports the first results towards the realization of an optical clock using trapped strontium atoms. This set up would combine advantages of the different approaches commonly used to develop an atomic frequency standard. The first part describes the cold atoms source which is implemented. A magneto-optical trap operating on the {sup 1}S{sub 0}-{sup 1}P{sub 1} transition at 461 nm is loaded from an atomic beam decelerated by a Zeeman slower. The 461 nm laser is obtained by sum-frequency mixing in a potassium titanyl phosphate (KTP) crystal. The second part is devoted to the different stages developed to achieve the direct excitation of the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition in {sup 87}Sr. This line has a theoretical natural width of 10{sup -3} Hz. Before this detection, we obtained an estimate of the resonance frequency by measuring absolute frequencies of several allowed optical transitions. (author)

The burden of cesium 137 in forest clerks

International Nuclear Information System (INIS)

Piechotowski, I.; Jaroni, J.; Link, B.; Groezinger, O.

2000-01-01

In 47 forest clerks from the regions Ortenau and Oberschwaben in south-west Germany the incorporation of cesium 137 and potassium 40 was measured in autumn 1994. Soil burden as well as burden of nutrition with cesium 137 are different in these regions for geological reasons and as a result of the nuclear accident of Chernobyl. Caused by low content of clay in Oberschwaben, the transfer of cesium to plants is assisted. Heavy rainfall after the nuclear accident led to an additional increase of burden. The median of the concentration of cesium 137 was 1.4 Bq/kg body weight. The median for potassium 40 was 58 Bq/kg body weight. For cesium 137 regional differences were observed. For persons from Oberschwaben the median for cesium 137 was with 2.8 Bq/kg body weight clearly higher than for persons from Ortenau with 0,6 Bq/kg body weight. Concerning nutrition habits, the clearest difference was found comparing persons who had ate a minimum of four portions of deer from the surroundings within the last four weeks with persons who had ate less than four portions of deer from the surroundings within the last four weeks. The difference was greater in Oberschwaben than in Ortenau. The effective dose of cesium 137 calculated on the basis of the incorporation is very low compared to natural radiation. This is also valid for persons from Oberschwaben. (orig.) [de

Micro-PIXE evaluation of radioactive cesium transfer in contaminated soil samples

International Nuclear Information System (INIS)

Fujishiro, F.; Ishii, K.; Matsuyama, S.; Arai, H.; Ishizaki, A.; Osada, N.; Sugai, H.; Kusano, K.; Nozawa, Y.; Yamauchi, S.; Karahashi, M.; Oshikawa, S.; Kikuchi, K.; Koshio, S.; Watanabe, K.; Suzuki, Y.

2014-01-01

Highlights: • There are radioactively contaminated soils having a radioactive cesium transfer of 0.01. • Micro-PIXE analysis has revealed an existence of phosphorus in a contaminated soil. • Radioactive cesium captured by phosphorus compound would be due to radioactive transfer. -- Abstract: Micro-PIXE analysis has been performed on two soil samples with high cesium activity concentrations. These soil samples were contaminated by fallout from the accident at Fukushima Daiichi Nuclear Power Plant. One exhibits a radioactive cesium transfer of ∼0.01, and the other shows a radioactive cesium transfer of less than 0.001, even though both samples have high cesium activity concentrations exceeding 10,000 Bq/kg. X-ray spectra and elemental images of the soil samples revealed the presence of chlorine, which can react with cesium to produce an inorganic soluble compound, and phosphorus-containing cesium-capturable organic compounds

Method for synthesizing pollucite from chabazite and cesium chloride

International Nuclear Information System (INIS)

Pereira, C.

1999-01-01

A method is described for immobilizing waste chlorides salts containing radionuclides and hazardous nuclear material for permanent disposal, and in particular, a method is described for immobilizing waste chloride salts containing cesium, in a synthetic form of pollucite. The method for synthesizing pollucite from chabazite and cesium chloride includes mixing dry, non-aqueous cesium chloride with chabazite and heating the mixture to a temperature greater than the melting temperature of the cesium chloride, or above about 700 C. The method further comprises significantly improving the rate of retention of cesium in ceramic products comprised of a salt-loaded zeolite by adding about 10% chabazite by weight to the salt-loaded zeolite prior to conversion at elevated temperatures and pressures to the ceramic composite. 3 figs

Low-temperature phase transformation in rubidium and cesium superoxides

International Nuclear Information System (INIS)

Alikhanov, R.A.; Toshich, B.S.; Smirnov, L.S.

1980-01-01

Crystal structures of rubidium and cesium superoxides which are two interpenetrating lattices of metal ions and oxygen molecule ions reveal a number of phase transformations with temperature decrease. Crystal-phase transformations in CsO 2 are 1-2, 2-3 and low temperature one 3-4 at 378, 190 and 10 K. Low temperature transition is considered as the instability of lattice quadrupoles of oxygen molecule ions to phase transformation of the order-disorder type. Calculated temperatures of low temperature phase transformations in PbO 2 and CsO 2 agree with experimental calculations satisfactory [ru

A Light Clock Satisfying the Clock Hypothesis of Special Relativity

Science.gov (United States)

West, Joseph

2007-01-01

The design of the FMEL, a floor-mirrored Einstein-Langevin "light clock", is introduced. The clock provides a physically intuitive manner to calculate and visualize the time dilation effects for a spatially extended set of observers (an accelerated "frame") undergoing unidirectional acceleration or observers on a rotating cylinder of constant…

Micro-PIXE evaluation of radioactive cesium transfer in contaminated soil samples

Science.gov (United States)

Fujishiro, F.; Ishii, K.; Matsuyama, S.; Arai, H.; Ishizaki, A.; Osada, N.; Sugai, H.; Kusano, K.; Nozawa, Y.; Yamauchi, S.; Karahashi, M.; Oshikawa, S.; Kikuchi, K.; Koshio, S.; Watanabe, K.; Suzuki, Y.

2014-01-01

Micro-PIXE analysis has been performed on two soil samples with high cesium activity concentrations. These soil samples were contaminated by fallout from the accident at Fukushima Daiichi Nuclear Power Plant. One exhibits a radioactive cesium transfer of ˜0.01, and the other shows a radioactive cesium transfer of less than 0.001, even though both samples have high cesium activity concentrations exceeding 10,000 Bq/kg. X-ray spectra and elemental images of the soil samples revealed the presence of chlorine, which can react with cesium to produce an inorganic soluble compound, and phosphorus-containing cesium-capturable organic compounds.

Sorption of cesium on titanium and zirconium phosphates

International Nuclear Information System (INIS)

Lebedev, V.N.; Mel'nik, N.A.; Rudenko, A.V.

2003-01-01

Titanium and zirconium phosphates were prepared from mineral raw materials of the Kola Peninsula. Their capability to recover cesium cations from the model solutions and liquid radioactive waste (LRW) was studied. Titanium phosphate prepared from solutions formed by titanite breakdown demonstrates greater distribution coefficients of cesium as compared to zirconium phosphate. Titanium phosphate as a cheaper agent featuring greater sorption capacity was recommended for treatment of LRW to remove cesium [ru

Cesium-137 in ash from combustion of biofuels. Application of regulations from the Swedish Radiation Safety Authority

International Nuclear Information System (INIS)

Sjoeblom, Rolf

2009-01-01

. The differences are large. The transitions between Cesium/Potassium in the pore water and in the exchangeable positions are rapid. Other transitions are slow. Over the course of a few years, Cesium becomes bonded as non-exchangeable and after a few decades, the content of non-exchangeable and mineral Cesium may be comparable in magnitude. The migration rate depends on the availability. Before Cesium-137 in fallout becomes absorbed, it is transported with the water, and this is the reason for the initial rapid penetration into soil on the order of a decimeter. When most of the Cesium-137 has become non-exchangeable and mineral, the migration rate may be as low as on the order of a millimetre per year. There is an interesting finding to report about clay. For short term migration, i e shortly after a fallout, clay provides a retention that is far superior to that of sand. This is probably related to the fact that clay contains many more positions for ion exchange as compared to sand. After some time when most of the Cesium appears in non-exchangeable and mineral positions, clay and sand are comparable. It might be tempting to assume that organic soils would provide a good retention since they can absorb nutrients from artificial fertilizers and keep them available to plants. Measurements have shown, however, that Cesium-137 may migrate rapidly in soils that lack a mineral component, e g soils consisting of peat. This can be assumed to relate to the fact that the bonding to the many exchangeable positions is much weaker as compared to those in non-exchangeable and in mineral positions. The data on ash are scarce. The data found indicate that the availability of Cesium-137 is high in fresh ash, but that the bonding is remarkably strong already after a few years. It cannot be taken for granted without further information that fresh water conditions apply also when the salt content in the pore water is high. Investigations have shown, however, that the solid mineral phase

Cesium-137 inventories in undisturbed areas in different regions of Brazil

Energy Technology Data Exchange (ETDEWEB)

Andrello, Avacir C.; Appoloni, Carlos R., E-mail: acandrello@uel.b [Universidade Estadual de Londrina, PR (Brazil). Dept. de Fisica; Araujo, Ednaldo S. [EMBRAPA Agrobiologia, Seropedica, RJ (Brazil); Thomaz, Edivaldo L. [Universidade Estadual do Centro-Oeste - UNICENTRO, Guarapuava, PR (Brazil). Dept. de Geografia; Medeiros, Pedro Henrique Augusto [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil). Dept. de Engenharia Agricola; Macedo, Iris L. [Universidade de Brasilia (UnB), DF (Brazil). Faculdade de Tecnologia. Dept. de Engenharia Civil e Ambiental

2009-07-01

Cesium-137 is an anthropogenic radionuclide introduced in the environment in the early of 1960s to the end of 1970s. The Cesium-137 has very used to assess soil redistribution in the landscape because this is very tight in the fine soil particles and its movement in the landscape is due to soil redistribution. To use Cesium-137 to assess soil redistribution is need to known the Cesium-137 inventory in an area that not has experimented soil erosion neither soil deposition. So, this work present Cesium-137 inventories in undisturbed areas in different regions of Brazil, from South to Northeast of Brazil. The inventories in these areas represent the variational deposition of Cesium-137 in the whole national territory of Brazil. The inventories of Cesium-137 varied from 200 +- 15 Bq.m{sup -2} for South region to 15 +- 2 Bq.m{sup -2} for Northeast region. Moreover, was verified that the Cesium- 137 inventories depend on latitude and altitude of the area. (author)

Cesium-137 inventories in undisturbed areas in different regions of Brazil

International Nuclear Information System (INIS)

Andrello, Avacir C.; Appoloni, Carlos R.; Thomaz, Edivaldo L.; Medeiros, Pedro Henrique Augusto; Macedo, Iris L.

2009-01-01

Cesium-137 is an anthropogenic radionuclide introduced in the environment in the early of 1960s to the end of 1970s. The Cesium-137 has very used to assess soil redistribution in the landscape because this is very tight in the fine soil particles and its movement in the landscape is due to soil redistribution. To use Cesium-137 to assess soil redistribution is need to known the Cesium-137 inventory in an area that not has experimented soil erosion neither soil deposition. So, this work present Cesium-137 inventories in undisturbed areas in different regions of Brazil, from South to Northeast of Brazil. The inventories in these areas represent the variational deposition of Cesium-137 in the whole national territory of Brazil. The inventories of Cesium-137 varied from 200 ± 15 Bq.m -2 for South region to 15 ± 2 Bq.m -2 for Northeast region. Moreover, was verified that the Cesium- 137 inventories depend on latitude and altitude of the area. (author)

Circadian clock, cell cycle and cancer

Directory of Open Access Journals (Sweden)

Cansu Özbayer

2011-12-01

Full Text Available There are a few rhythms of our daily lives that we are under the influence. One of them is characterized by predictable changes over a 24-hour timescale called circadian clock. This cellular clock is coordinated by the suprachiasmatic nucleus in the anterior hypothalamus. The clock consist of an autoregulatory transcription-translation feedback loop compose of four genes/proteins; BMAL1, Clock, Cyrptochrome, and Period. BMAL 1 and Clock are transcriptional factors and Period and Cyrptochrome are their targets. Period and Cyrptochrome dimerize in the cytoplasm to enter the nucleus where they inhibit Clock/BMAL activity.It has been demonstrate that circadian clock plays an important role cellular proliferation, DNA damage and repair mechanisms, checkpoints, apoptosis and cancer.

Surface interactions of cesium and boric acid with stainless steel

International Nuclear Information System (INIS)

Grossman-Canfield, N.

1995-08-01

In this report, the effects of cesium hydroxide and boric acid on oxidized stainless steel surfaces at high temperatures and near one atmosphere of pressure are investigated. This is the first experimental investigation of this chemical system. The experimental investigations were performed using a mass spectrometer and a mass electrobalance. Surfaces from the different experiments were examined using a scanning electron microscope to identify the presence of deposited species, and electron spectroscopy for chemical analysis to identify the species deposited on the surface. A better understanding of the equilibrium thermodynamics, the kinetics of the steam-accelerated volatilizations, and the release kinetics are gained by these experiments. The release rate is characterized by bulk vaporization/gas-phase mass transfer data. The analysis couples vaporization, deposition, and desorption of the compounds formed by cesium hydroxide and boric acid under conditions similar to what is expected during certain nuclear reactor accidents. This study shows that cesium deposits on an oxidized stainless steel surface at temperatures between 1000 and 1200 Kelvin. Cesium also deposits on stainless steel surfaces coated with boric oxide in the same temperature ranges. The mechanism for cesium deposition onto the oxide layer was found to involve the chemical reaction between cesium and chromate. Some revaporization in the cesium hydroxide-boric acid system was observed. It has been found that under the conditions given, boric acid will react with cesium hydroxide to form cesium metaborate. A model is proposed for this chemical reaction

Hanford waste encapsulation: strontium and cesium

International Nuclear Information System (INIS)

Jackson, R.R.

1976-06-01

The strontium and cesium fractions separated from high radiation level wastes at Hanford are converted to the solid strontium fluoride and cesium chloride salts, doubly encapsulated, and stored underwater in the Waste Encapsulation and Storage Facility (WESF). A capsule contains approximately 70,000 Ci of 137 Cs or 70,000 to 140,000 Ci of 90 Sr. Materials for fabrication of process equipment and capsules must withstand a combination of corrosive chemicals, high radiation dosages and frequently, elevated temperatures. The two metals selected for capsules, Hastelloy C-276 for strontium fluoride and 316-L stainless steel for cesium chloride, are adequate for prolonged containment. Additional materials studies are being done both for licensing strontium fluoride as source material and for second generation process equipment

Optically trapped atom interferometry using the clock transition of large {sup 87}Rb Bose-Einstein condensates

Energy Technology Data Exchange (ETDEWEB)

Altin, P A; McDonald, G; Doering, D; Debs, J E; Barter, T H; Close, J D; Robins, N P [Department of Quantum Science, ARC Centre of Excellence for Quantum Atom Optics, the Australian National University, ACT 0200 (Australia); Haine, S A [School of Mathematics and Physics, ARC Centre of Excellence for Quantum-Atom Optics, The University of Queensland, Queensland 4072 (Australia); Hanna, T M [Joint Quantum Institute, National Institute of Standards and Technology and University of Maryland, 100 Bureau Drive, Stop 8423, Gaithersburg, MD 20899-8423 (United States); Anderson, R P, E-mail: paul.altin@anu.edu.au [School of Physics, Monash University, VIC 3800 (Australia)

2011-06-15

We present a Ramsey-type atom interferometer operating with an optically trapped sample of 10{sup 6} Bose-condensed {sup 87}Rb atoms. We investigate this interferometer experimentally and theoretically with an eye to the construction of future high precision atomic sensors. Our results indicate that, with further experimental refinements, it will be possible to produce and measure the output of a sub-shot-noise-limited, large atom number BEC-based interferometer. The optical trap allows us to couple the |F=1, m{sub F}=0){yields}|F=2, m{sub F}=0) clock states using a single photon 6.8 GHz microwave transition, while state selective readout is achieved with absorption imaging. We analyse the process of absorption imaging and show that it is possible to observe atom number variance directly, with a signal-to-noise ratio ten times better than the atomic projection noise limit on 10{sup 6} condensate atoms. We discuss the technical and fundamental noise sources that limit our current system, and present theoretical and experimental results on interferometer contrast, de-phasing and miscibility.

Axial migratin of cesium in LMFBR fuel pins

International Nuclear Information System (INIS)

Karnesky, R.A.; Bridges, A.E.; Jost, J.W.

1981-11-01

A correlated model for quantitatively predicting the behavior of cesium in LMFBR fuel pins has been developed. This correlation was shown to be in good agreement with experimental data. It has been used to predict the behavior of cesium in the FFTF driver fuel and as the result of this analysis it has been shown that the accumulation of cesium in the insulator pellets at the ends of the fuel column will not be life limiting

Cesium glass irradiation sources

International Nuclear Information System (INIS)

Plodinec, M.J.

1982-01-01

The precipitation process for the decontamination of soluble SRP wastes produces a material whose radioactivity is dominated by 137 Cs. Potentially, this material could be vitrified to produce irradiation sources similar to the Hanford CsCl sources. In this report, process steps necessary for the production of cesium glass irradiation sources (CGS), and the nature of the sources produced, are examined. Three options are considered in detail: direct vitrification of precipitation process waste; direct vitrification of this waste after organic destruction; and vitrification of cesium separated from the precipitation process waste. Direct vitrification is compatible with DWPF equipment, but process rates may be limited by high levels of combustible materials in the off-gas. Organic destruction would allow more rapid processing. In both cases, the source produced has a dose rate of 2 x 10 4 rads/hr at the surface. Cesium separation produces a source with a dose rate of 4 x 10 5 at the surface, which is nearer that of the Hanford sources (2 x 10 6 rads/hr). Additional processing steps would be required, as well as R and D to demonstrate that DWPF equipment is compatible with this intensely radioactive material

A tentative assessment of cesium 137 direct and indirect transfer rates in a simplified fresh water food chain

International Nuclear Information System (INIS)

Foulquier, Luc; Lambrechts, Alain.

1982-08-01

A comparison was made of the direct transfer of cesium from water to carps and the indirect transfer via the food. In a first experiment on chronic contamination of carps by water, the kinetics and distribution of cesium in the organs of the carps were studied. Equilibrium was not reached on the 56th day, 4% of the initial water activity had been retained by the carps and the concentration factor was below 10. The highest specific activities were found in the transit organs. In a second experiment, the water activity varied by alternating contamination and decontamination. A fluctuating equilibrium was reached on the 22nd day. The concentration factor was of the same order of magnitude than in the previous experiment. Indirect contamination of fish by ingestion of contaminated daphnids was studied in a third experiment. Cesium levels in carps increased with the cumulated activities in meals, and the uptake rate in fish was 4%. Both decorporation and biological half-lives (30-40 days) were independent of the contamination routes. The respective significance of the transfer pathways is discussed taking into account the biomass pyramids to be found in the nature. It is estimated that in a cesium environment, 70% of the carp activity should come from the diet and 30% from the water. The concentration factor would then be 75 instead of 22 when only direct transfer of cesium from water to fish is considered [fr

Study of additive manufactured microwave cavities for pulsed optically pumped atomic clock applications

Science.gov (United States)

Affolderbach, C.; Moreno, W.; Ivanov, A. E.; Debogovic, T.; Pellaton, M.; Skrivervik, A. K.; de Rijk, E.; Mileti, G.

2018-03-01

Additive manufacturing (AM) of passive microwave components is of high interest for the cost-effective and rapid prototyping or manufacture of devices with complex geometries. Here, we present an experimental study on the properties of recently demonstrated microwave resonator cavities manufactured by AM, in view of their applications to high-performance compact atomic clocks. The microwave cavities employ a loop-gap geometry using six electrodes. The critical electrode structures were manufactured monolithically using two different approaches: Stereolithography (SLA) of a polymer followed by metal coating and Selective Laser Melting (SLM) of aluminum. The tested microwave cavities show the desired TE011-like resonant mode at the Rb clock frequency of ≈6.835 GHz, with a microwave magnetic field highly parallel to the quantization axis across the vapor cell. When operated in an atomic clock setup, the measured atomic Rabi oscillations are comparable to those observed for conventionally manufactured cavities and indicate a good uniformity of the field amplitude across the vapor cell. Employing a time-domain Ramsey scheme on one of the SLA cavities, high-contrast (34%) Ramsey fringes are observed for the Rb clock transition, along with a narrow (166 Hz linewidth) central fringe. The measured clock stability of 2.2 × 10-13 τ-1/2 up to the integration time of 30 s is comparable to the current state-of-the-art stabilities of compact vapor-cell clocks based on conventional microwave cavities and thus demonstrates the feasibility of the approach.

Spatial variability and Cesium-137 inventories in native forest

International Nuclear Information System (INIS)

Andrello, A.C.; Appoloni, C.R.

2004-01-01

With the nuclear fission discovery and development of nuclear weapons in 1940s, artificial radioisotopes were introduced in the environment. This contamination is due to worldwide fallout by superficial nuclear tests realized from early 1950s to late 1970s by USA, former URSS, UK, France and China. One of theses radioisotopes that have been very studied is cesium-137. Cesium-137 has a half-life of 30.2 years and its biological behavior is similar to the potassium. The behavior in soil matrix, depth distribution, spatial variability and inventories values of cesium-137 has been determinate for several regions of the world. In Brazil, some research groups have worked on this subject, but there are few works published about theses properties of cesium-137. The aim of this paper was study the depth distribution, spatial variability, and inventory of cesium-137 in native forest. Two native forests (Mata 1 and Mata UEL) were sampling in region of Londrina, PR. The results shows that there is a spatial variability of 40% for Mata 1 and 42% for Mata UEL. The depth distribution of cesium-137 for two forests presented a exponential form, characteristic to undisturbed soil. Cesium-137 inventory determinate for Mata 1 was 358 Bq m -2 and for Mata UEL was 320 Bq m -2 . (author)

Decorporation of cesium-137

International Nuclear Information System (INIS)

Le Fleche, Ph.; Destombe, C.; Grasseau, A.; Mathieu, J.; Chancerelle, Y.; Mestries, J.C.

1997-01-01

Cesium radio-isotopes, especially cesium-137 ( 137 Cs) are among the radionuclides of main importance produced by a fission reaction in reactor or a nuclear weapon explosion. In the environment, 137 Cs is a major contaminant which can cause severe β, γirradiations and contaminations. 137 Cs is distributed widely and relatively uniformly throughout the body with the highest concentration in skeletal muscles. A treatment becomes difficult afterwards. The purposes of this report are Firstly to compare the Prussian blue verses cobalt and potassium ferrocyanide (D.I. blue) efficiency for the 137 Cs decorporation and secondly to assess a chronological treatment with D.I. blue. (author)

Conceptual design of cesium removal device for ITER NBI maintenance

Energy Technology Data Exchange (ETDEWEB)

Oka, Kiyoshi; Shibanuma, Kiyoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

2003-03-01

Cesium is required in order to generate a stable negative ion of hydrogen in an ion source of the neutral beam injector (NBI), which is one of the plasma-heating devices for International Thermonuclear Experimental Reactor (ITER). After long time operation of the NBI, the cesium deposits to the insulators supporting the electrode. Due to the deterioration of the insulation resistance, the continuous operation of the NBI will be difficult. In addition, the NBI device is activated by neutrons from D-T plasma, so that periodic removal and cleaning of the cesium on the insulators by remove handling is required. A study of the cesium removal scenario and the device is therefore required considering remote handling. In this report, a cesium removal procedure and conceptual design of the cesium removal device using laser ablation technique are studied, and the feasibility of the laser ablation method is shown. (author)

Controllable clock circuit design in PEM system

International Nuclear Information System (INIS)

Sun Yunhua; Wang Peihua; Hu Tingting; Feng Baotong; Shuai Lei; Huang Huan; Wei Shujun; Li Ke; Zhao Jingwei; Wei Long

2011-01-01

A high-precision synchronized clock circuit design will be presented, which can supply steady, reliable and anti-jamming clock signal for the data acquirement (DAQ) system of Positron Emission Mammography (PEM). This circuit design is based on the Single-Chip Microcomputer and high-precision clock chip, and can achieve multiple controllable clock signals. The jamming between the clock signals can be reduced greatly with the differential transmission. Meanwhile, the adoption of CAN bus control in the clock circuit can prompt the clock signals to be transmitted or masked simultaneously when needed. (authors)

Controllable clock circuit design in PEM system

International Nuclear Information System (INIS)

Sun Yunhua; Wang Peilin; Hu Tingting; Feng Baotong; Shuai Lei; Huang Huan; Wei Shujun; Li Ke; Zhao Jingwei; Wei Long

2010-01-01

A high-precision synchronized clock circuit design will be presented, which can supply steady, reliable and anti-jamming clock signal for the data acquirement (DAQ) system of Positron Emission Mammography (PEM). This circuit design is based on the Single-Chip Microcomputer and high-precision clock chip, and can achieve multiple controllable clock signals. The jamming between the clock signals can be reduced greatly with the differential transmission. Meanwhile, the adoption of CAN bus control in the clock circuit can prompt the clock signals to be transmitted or masked simultaneously when needed. (authors)

Extraction of cesium from acid solutions

International Nuclear Information System (INIS)

Katykhin, G.S.; Simonov, A.S.

1983-01-01

The extraction of cesium from acidic solutions is studied. Halogen-substituted carboxylic acids were chosen for the aqueous phase and nitrobenzene the diluent. The distribution coefficients are determined by the use of radioactive tracers 134 Cs and 137 Cs. It is believed that large singly charged anions of strong acids are necessary for the extraction of cesium. Metal halide acids are selected for supplying the anions

GPS Composite Clock Analysis

OpenAIRE

Wright, James R.

2008-01-01

The GPS composite clock defines GPS time, the timescale used today in GPS operations. GPS time is illuminated by examination of its role in the complete estimation and control problem relative to UTC/TAI. The phase of each GPS clock is unobservable from GPS pseudorange measurements, and the mean phase of the GPS clock ensemble (GPS time) is unobservable. A new and useful observability definition is presented, together with new observability theorems, to demonstrate explicitly that GPS time is...

Cesium in the nutrient cycle

International Nuclear Information System (INIS)

Rantavaara, A.

1992-01-01

Most radioactive cesium in forests is deposited in soil, from which it passes into berries and mushrooms, and further to game. The cesium contents of Finnish berries and mushrooms vary depending on the intensity of Chernobyl fallout. Northern Haeme, Pirkanmaa and parts of central Finland received the most fallout. Weather conditions and the environmental factors, and other circumstances during the growth period, also affect the contents. However, consumption of wild berries, mushrooms and game need not be restricted because of radioactivity anywhere in Finland

Precision spectroscopy on atomic hydrogen

International Nuclear Information System (INIS)

Parthey, Christian Godehard

2011-01-01

This Thesis reports on three measurements involving the 1S-2S transition in atomic hydrogen and deuterium conducted on a 5.8 K atomic beam. The transition is excited Doppler-free via two counter-propagating photons near 243 nm. The H/D isotope shift has been determined as Δ∫ exp =670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, Δ∫ th =670 999 566.90(66)(60) kHz we confirm, twice more accurate, the rms charge radius difference of the deuteron and the proton as left angle r 2 right angle d - left angle r 2 right angle p =3.82007(65) fm 2 and the deuteron structure radius r str =1.97507(78) fm. The frequency ratio of the 1S-2S transition in atomic hydrogen to the cesium ground state hyperfine transition provided by the mobile cesium fountain clock FOM is measured to be ∫ 1S-2S =2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10 -15 . The second absolute frequency measurement of the 1S-2S transition in atomic hydrogen presents the first application of a 900 km fiber link between MPQ and Physikalisch- Technische Bundesanstalt (PTB) in Braunschweig which we have used to calibrate the MPQ hydrogen maser with the stationary cesium fountain clock CSF1 at PTB. With the result of ∫ 1S-2S =2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c (TX) -0.29c (TY) -0.08 c (TZ) =(2.2±1.8) x 10 -11 within the framework of minimal standard model extensions. We limit a possible drift of the strong coupling constant through the ratio of magnetic moments at a competitive level (∂)/(∂t)ln (μ Cs )/(μ B )=-(3.0±1.2) x 10 -15 yr -1 .

A clock and data recovery method based on phase detector implemented by delay chain in FPGA

International Nuclear Information System (INIS)

Xie Mingpu; Wu Jie; Zhang Jie

2009-01-01

A clock and data recovery method based on charge pump PLL was developed to archive medium data rate serial digital communication with simple line transceivers. The phase detector was realized by FPGA. A delay chain was constructed by delay elements with the same fixed delay. Every output of the delay elements was latched by the VCO output clock when the input signal went through the delay chain. The latched result was used to detect the data transition, which reflected the phase difference between the input signal and the VCO output clock. The VCO control voltage was adjust by charge pump to reduce the phase difference and archive phase lock. The loop filter was a passive filter,parameters of which were calculated from parameters of the delay chain and VCO. The experimental result shows that the clock of a 64Mbps transmission was recovered with a jitter less than 200 ps. (authors)

Removal of cesium radioisotopes from solutions using granulated zeolites

International Nuclear Information System (INIS)

Bronic, J.; Subotic, B.

1991-01-01

The influence of type of zeolite and the flow rate of solution through the column on the removal efficiency of radioactive cesium ions from solution has been investigated. The analysis of the change in the concentration of cesium ions in the solutions and distribution of cesium ions in the column fillings (granulated zeolites), after passing the solutions through the columns filled with various granulated zeolites (zeolite 4A, zeolite 13X, synthetic mordenite) was performed. On the basis of the results of this study, the conditions for the most efficient removal of cesium ions from solutions have been discussed. (author) 35 refs.; 9 figs.; 1 tab

Characterization of a clock based on coherent population trapping in a thermal cesium vapor. Main effects that may affect its mid- and long-term frequency stability

International Nuclear Information System (INIS)

Kozlova, Olga

2013-01-01

This thesis describes a Cs - buffer gas vapor cell atomic clock based on coherent population trapping (CPT), and the main frequency shifts affecting its mid- and long-term stability. The developed atomic clock based on CPT uses two original techniques: a so-called double-Λ scheme for the CPT-resonance excitation and a temporal Ramsey interrogation technique, which produce a high contrast and narrow resonances with reduced light shift dependence. Generally, the mid and long term stability of the vapor cell atomic clock is limited by the collisional shift induced by alkali-buffer gas collisions and the light shift (or the effects depending on the laser intensity). We report on the study of the collisional shift of Cs clock frequency in the presence of Ne, N 2 or Ar buffer gas, and its temperature dependence. The coefficient values of this dependence for these three buffer gases were revealed (some of them for the first time), allowing us to realise a cell with optimal combination of buffer gases to cancel the temperature dependence around the working temperature. Following the study of the signal amplitude and the coherence relaxation rate the optimal values for such parameters as interrogation cycle, magnetic field, cell temperature, pressure of the buffer gas mixture, etc. were found for the chosen cell. The investigation on the light shift and the effects depending on the laser intensity allowed us to determine the most sensitive parameters (laser intensity ratio, temperature) and to implement the required stabilizations in order to better control them. Finally, the mid- and long-term clock frequency stability was improved by a factor 40, reaching 2.5 10 -14 at 1 hour. (author)

Study of strontium and cesium migration in fractured crystalline rock

International Nuclear Information System (INIS)

Gustafsson, E.; Klockars, C.E.

1984-01-01

The purpose of this investigation has been to study the retardation and dilution of non-active strontium and cesium relative to a non-absorbing substance (iodide) in a well-defined fracture zone in the Finnsjoen field research area. The investigation was carried out in a previously tracer-tested fracture zone. The study has encompassed two separate test runs with prolonged injection of strontium and iodide and of cesium and iodide. The test have shown that: - Strontium is not retarded, but rather absorbed to about 40% at equilibrium. - At injection stop, 36.3% of the injected mass of strontium has been absorbed and there is no deabsorption. -Cesium is retarded a factor of 2-3 and absorbed to about 30% at equilibrium. - At injection stop, 39.4% of the injected mass of cesium has been absorbed. Cesium is deabsorbed after injection stop (400h) and after 1300 hours, only 22% of the injected mass of cesium is absorbed. (author)

Automatic control of clock duty cycle

Science.gov (United States)

Feng, Xiaoxin (Inventor); Roper, Weston (Inventor); Seefeldt, James D. (Inventor)

2010-01-01

In general, this disclosure is directed to a duty cycle correction (DCC) circuit that adjusts a falling edge of a clock signal to achieve a desired duty cycle. In some examples, the DCC circuit may generate a pulse in response to a falling edge of an input clock signal, delay the pulse based on a control voltage, adjust the falling edge of the input clock signal based on the delayed pulse to produce an output clock signal, and adjust the control voltage based on the difference between a duty cycle of the output clock signal and a desired duty cycle. Since the DCC circuit adjusts the falling edge of the clock cycle to achieve a desired duty cycle, the DCC may be incorporated into existing PLL control loops that adjust the rising edge of a clock signal without interfering with the operation of such PLL control loops.

A highly miniaturized vacuum package for a trapped ion atomic clock

Energy Technology Data Exchange (ETDEWEB)

Schwindt, Peter D. D., E-mail: pschwin@sandia.gov; Jau, Yuan-Yu; Partner, Heather; Casias, Adrian; Wagner, Adrian R.; Moorman, Matthew; Manginell, Ronald P. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Kellogg, James R.; Prestage, John D. [Jet Propulsion Laboratory, Pasadena, California 91109 (United States)

2016-05-15

We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm{sup 3} in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, it was sealed with a copper pinch-off and was subsequently pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of {sup 171}Y b{sup +}. The fractional frequency stability of the clock was measured to be 2 × 10{sup −11}/τ{sup 1/2}.

Cesium vapor cycle for an advanced LMFBR

International Nuclear Information System (INIS)

Fraas, A.P.

1975-01-01

A review indicates that a cesium vapor topping cycle appears attractive for use in the intermediate fluid circuit of an advanced LMFBR designed for a reactor outlet temperature of 1250 0 F or more and would have the following advantages: (1) it would increase the thermal efficiency by about 5 to 10 points (from approximately 40 percent to approximately 45 to 50 percent) thus reducing the amount of waste heat rejected to the environment by 15 to 30 percent. (2) the higher thermal efficiency should reduce the overall capital cost of the reactor plant in dollars per kilowatt. (3) the cesium can be distilled out of the intermediate fluid circuit to leave it bone-dry, thus greatly reducing the time and cost of maintenance work (particularly for the steam generator). (4) the large volume and low pressure of the cesium vapor region in the cesium condenser-steam generator greatly reduces the magnitude of pressure fluctuations that might occur in the event of a leak in a steam generator tube, and the characteristics inherent in a condenser make it easy to design for rapid concentration of any noncondensibles that may form as a consequence of a steam leak into the cesium region so that a steam leak can be detected easily in the very early stages of its development

Characterization of atomic spin polarization lifetime of cesium vapor cells with neon buffer gas

Science.gov (United States)

Lou, Janet W.; Cranch, Geoffrey A.

2018-02-01

The dephasing time of spin-polarized atoms in an atomic vapor cell plays an important role in determining the stability of vapor-cell clocks as well as the sensitivity of optically-pumped magnetometers. The presence of a buffer gas can extend the lifetime of these atoms. Many vapor cell systems operate at a fixed (often elevated) temperature. For ambient temperature operation with no temperature control, it is necessary to characterize the temperature dependence as well. We present a spin-polarization lifetime study of Cesium vapor cells with different buffer gas pressures, and find good agreement with expectations based on the combined effects of wall collisions, spin exchange, and spin destruction. For our (7.5 mm diameter) vapor cells, the lifetime can be increased by two orders of magnitude by introducing Ne buffer gas up to 100 Torr. Additionally, the dependence of the lifetime on temperature is measured (25 - 47 oC) and simulated for the first time to our knowledge with reasonable agreement.

Atomic and gravitational clocks

International Nuclear Information System (INIS)

Canuto, V.M.; City Coll., New York; Goldman, I.

1982-01-01

Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous-whose rates are related by a non-constant function βsub(a)-is demonstrated. The cosmological character of βsub(a) is also discussed. (author)

Colour As a Signal for Entraining the Mammalian Circadian Clock

Science.gov (United States)

Walmsley, Lauren; Hanna, Lydia; Mouland, Josh; Martial, Franck; West, Alexander; Smedley, Andrew R.; Bechtold, David A.; Webb, Ann R.; Lucas, Robert J.; Brown, Timothy M.

2015-01-01

Twilight is characterised by changes in both quantity (“irradiance”) and quality (“colour”) of light. Animals use the variation in irradiance to adjust their internal circadian clocks, aligning their behaviour and physiology with the solar cycle. However, it is currently unknown whether changes in colour also contribute to this entrainment process. Using environmental measurements, we show here that mammalian blue–yellow colour discrimination provides a more reliable method of tracking twilight progression than simply measuring irradiance. We next use electrophysiological recordings to demonstrate that neurons in the mouse suprachiasmatic circadian clock display the cone-dependent spectral opponency required to make use of this information. Thus, our data show that some clock neurons are highly sensitive to changes in spectral composition occurring over twilight and that this input dictates their response to changes in irradiance. Finally, using mice housed under photoperiods with simulated dawn/dusk transitions, we confirm that spectral changes occurring during twilight are required for appropriate circadian alignment under natural conditions. Together, these data reveal a new sensory mechanism for telling time of day that would be available to any mammalian species capable of chromatic vision. PMID:25884537

Colour as a signal for entraining the mammalian circadian clock.

Directory of Open Access Journals (Sweden)

Lauren Walmsley

2015-04-01

Full Text Available Twilight is characterised by changes in both quantity ("irradiance" and quality ("colour" of light. Animals use the variation in irradiance to adjust their internal circadian clocks, aligning their behaviour and physiology with the solar cycle. However, it is currently unknown whether changes in colour also contribute to this entrainment process. Using environmental measurements, we show here that mammalian blue-yellow colour discrimination provides a more reliable method of tracking twilight progression than simply measuring irradiance. We next use electrophysiological recordings to demonstrate that neurons in the mouse suprachiasmatic circadian clock display the cone-dependent spectral opponency required to make use of this information. Thus, our data show that some clock neurons are highly sensitive to changes in spectral composition occurring over twilight and that this input dictates their response to changes in irradiance. Finally, using mice housed under photoperiods with simulated dawn/dusk transitions, we confirm that spectral changes occurring during twilight are required for appropriate circadian alignment under natural conditions. Together, these data reveal a new sensory mechanism for telling time of day that would be available to any mammalian species capable of chromatic vision.

Bennett clocking of quantum-dot cellular automata and the limits to binary logic scaling

International Nuclear Information System (INIS)

Lent, Craig S; Liu Mo; Lu Yuhui

2006-01-01

We examine power dissipation in different clocking schemes for molecular quantum-dot cellular automata (QCA) circuits. 'Landauer clocking' involves the adiabatic transition of a molecular cell from the null state to an active state carrying data. Cell layout creates devices which allow data in cells to interact and thereby perform useful computation. We perform direct solutions of the equation of motion for the system in contact with the thermal environment and see that Landauer's Principle applies: one must dissipate an energy of at least k B T per bit only when the information is erased. The ideas of Bennett can be applied to keep copies of the bit information by echoing inputs to outputs, thus embedding any logically irreversible circuit in a logically reversible circuit, at the cost of added circuit complexity. A promising alternative which we term 'Bennett clocking' requires only altering the timing of the clocking signals so that bit information is simply held in place by the clock until a computational block is complete, then erased in the reverse order of computation. This approach results in ultralow power dissipation without additional circuit complexity. These results offer a concrete example in which to consider recent claims regarding the fundamental limits of binary logic scaling

Cesium and Strontium Separation Technologies Literature Review

Energy Technology Data Exchange (ETDEWEB)

T. A. Todd; T. A. Todd; J. D. Law; R. S. Herbst

2004-03-01

Integral to the Advanced Fuel Cycle Initiative (AFCI) Program’s proposed closed nuclear fuel cycle, the fission products cesium and strontium in the dissolved spent nuclear fuel stream are to be separated and managed separately. A comprehensive literature survey is presented to identify cesium and strontium separation technologies that have the highest potential and to focus research and development efforts on these technologies. Removal of these high-heat-emitting fission products reduces the radiation fields in subsequent fuel cycle reprocessing streams and provides a significant short-term (100 yr) heat source reduction in the repository. This, along with separation of actinides, may provide a substantial future improvement in the amount of fuel that could be stored in a geologic repository. The survey and review of the candidate cesium and strontium separation technologies are presented herein. Because the AFCI program intends to manage cesium and strontium together, technologies that simultaneously separate both elements are of the greatest interest, relative to technologies that separate only one of the two elements.

A VMEbus clock system for accelerator control

International Nuclear Information System (INIS)

Beechy, D.G.; McClure, C.R.

1992-01-01

Because an accelerator has many systems which must operate with a high degree of synchronization, a clock signal is typically generated which carries timing information to the various accelerator components. This paper discusses two VMEbus modules designed to generate and receive this clock signal. Together they implement a clock system which can generate timing markers with 200 nanosecond resolution and can generate timing delays of over one hour with one microsecond resolution. The Clock Generator module contains both a time line generator programmed to produce clock events at specific times and eight programmable input channels to produce clock events when externally triggered. Additional clock events are generated directly from the VMEbus. Generators can be cascaded for added capability. The Clock Timer module receives the signal from the generator. It can be programmed to recognize specific clock events which act as triggers to the eight timing channels on the module. Each timing channel is programmed with a 32-bit delay value. The channels are clocked at 1 MHz. At the end of the delay period, a timer channel produces an output pulse and optionally can generate a bus interrupt

METHOD FOR THE RECOVERY OF CESIUM VALUES

Science.gov (United States)

Rimshaw, S.J.

1960-02-16

A method is given for recovering Cs/sup 137/ from radioactive waste solutions together with extraneous impurities. Ammonium alum is precipitated in the waste solution. The alum, which carries the cesium, is separated from the supernatant liquid and then dissolved in water. The resulting aqueous solution is then provided with a source of hydroxyl ions, which precipitates aluminum as the hydroxide, and the aluminum hydroxide is separated from the resulting liquid. This liquid, which contains anionic impurities together with ammonium and cesium, is passed through an anion exchange resin bed which removes the anionic impurities. The ammonium in the effluent is removed by destructive distiilation, leaving a substantiaily pure cesium salt in the effluent.

Frequency shift due to blackbody radiation in a cesium atomic fountain and improvement of the clock performances

International Nuclear Information System (INIS)

Zhang, S.

2004-07-01

FO1 was the first caesium fountain primary frequency standard in the world. The most recent evaluation in 2002 before improvement reached an accuracy of 1*10 -15 when operated with optical molasses. Working as an extremely precise and stable instrument, FO1 has contributed to fundamental physics and technical measurements: - Frequency comparison between Cs and Rb fountains over an interval of 5 years sets an upper limit for a possible variation of the fine structure constant as |alpha/alpha| -15 /y. The resolution is about 5 times better than the previous test in our laboratory. The projected accuracy of the space clock PHARAO is 1*10 -16 . We confirmed its Ramsey cavity performance by testing the phase difference between the two interaction zones in FO1. The measured temperature T dependent frequency shift of the Cs clock induced by the blackbody radiation field is given as nu(T)=154(6)*10 -6 *(T/300) 4 [1+ε(T/300) 2 ] Hz with the theoretical value ε = 0,014. The obtained accuracy represents a 3 times improvement over the previous measurement by the PTB group. Some improvements have been carried out on FO1. The new FO1 version works directly with optical molasses loaded by a laser slowed atomic beam. The application of the adiabatic passage method to perform the state selection allows us to determine the atom number dependent frequency shifts due to the cold collision and cavity pulling effects at a level of of 10 -16 . Recently, the obtained frequency stability is 2,8*10 -14 *τ -1/2 for about 4*10 6 detected atoms. The accuracy is currently under evaluation, the expected value is a few times 10 -16 . (author)

Biochemical changes in rats under the influence of cesium chloride

Directory of Open Access Journals (Sweden)

N. M. Melnikova

2013-04-01

Full Text Available Cesium is lately accumulated actively in the environment, but its influence on human and ani­mal organism is the least studied among heavy metals. It is shown that the action of cesium chloride in rats caused significant changes in blood chemistry, which are characterized by a decrease of total protein content, pH, an increase in the level of urea, creatinine, glucose and total hemoglobin. The results showed that potassium content in all the studied organs and tissues of poisoned rats decreases under the action of cesium chloride. Histological examination of the heart tissue in rats poisoned with cesium chloride indicates the onset of pathology of cardiovascular system. It was found out that use of the drug “Asparkam” reduces the negative effect of cesium chloride on the body of rats.

An analysis of clock-shift experiments: is scatter increased and deflection reduced in clock-shifted homing pigeons?

Science.gov (United States)

Chappell

1997-01-01

Clock-shifting (altering the phase of the internal clock) in homing pigeons leads to a deflection in the vanishing bearing of the clock-shifted group relative to controls. However, two unexplained phenomena are common in clock-shift experiments: the vanishing bearings of the clock-shifted group are often more scattered (with a shorter vector length) than those of the control group, and the deflection of the mean bearing of the clock-shifted group from that of the controls is often smaller than expected theoretically. Here, an analysis of 55 clock-shift experiments performed in four countries over 21 years is reported. The bearings of the clock-shifted groups were significantly more scattered than those of controls and less deflected than expected, but these effects were not significantly different at familiar and unfamiliar sites. The possible causes of the effects are discussed and evaluated with reference to this analysis and other experiments. The most likely causes appear to be conflict between the directions indicated by the sun compass and either unshifted familiar visual landmarks (at familiar sites only) or the unshifted magnetic compass (possible at both familiar and unfamiliar sites).

Molecular cogs of the insect circadian clock.

Science.gov (United States)

Shirasu, Naoto; Shimohigashi, Yasuyuki; Tominaga, Yoshiya; Shimohigashi, Miki

2003-08-01

During the last five years, enormous progress has been made in understanding the molecular basis of circadian systems, mainly by molecular genetic studies using the mouse and fly. Extensive evidence has revealed that the core clock machinery involves "clock genes" and "clock proteins" functioning as molecular cogs. These participate in transcriptional/translational feedback loops and many homologous clock-components in the fruit fly Drosophila are also expressed in mammalian clock tissues with circadian rhythms. Thus, the mechanisms of the central clock seem to be conserved across animal kingdom. However, some recent studies imply that the present widely accepted molecular models of circadian clocks may not always be supported by the experimental evidence.

High Performance Clocks and Gravity Field Determination

Science.gov (United States)

Müller, J.; Dirkx, D.; Kopeikin, S. M.; Lion, G.; Panet, I.; Petit, G.; Visser, P. N. A. M.

2018-02-01

Time measured by an ideal clock crucially depends on the gravitational potential and velocity of the clock according to general relativity. Technological advances in manufacturing high-precision atomic clocks have rapidly improved their accuracy and stability over the last decade that approached the level of 10^{-18}. This notable achievement along with the direct sensitivity of clocks to the strength of the gravitational field make them practically important for various geodetic applications that are addressed in the present paper. Based on a fully relativistic description of the background gravitational physics, we discuss the impact of those highly-precise clocks on the realization of reference frames and time scales used in geodesy. We discuss the current definitions of basic geodetic concepts and come to the conclusion that the advances in clocks and other metrological technologies will soon require the re-definition of time scales or, at least, clarification to ensure their continuity and consistent use in practice. The relative frequency shift between two clocks is directly related to the difference in the values of the gravity potential at the points of clock's localization. According to general relativity the relative accuracy of clocks in 10^{-18} is equivalent to measuring the gravitational red shift effect between two clocks with the height difference amounting to 1 cm. This makes the clocks an indispensable tool in high-precision geodesy in addition to laser ranging and space geodetic techniques. We show how clock measurements can provide geopotential numbers for the realization of gravity-field-related height systems and can resolve discrepancies in classically-determined height systems as well as between national height systems. Another application of clocks is the direct use of observed potential differences for the improved recovery of regional gravity field solutions. Finally, clock measurements for space-borne gravimetry are analyzed along with

Cesium-134 and cesium-137 in honey bees and cheese samples collected in the U. S. after the Chernobyl accident

Energy Technology Data Exchange (ETDEWEB)

Ford, B C; Jester, W A; Griffith, S M; Morse, R A; Zall, R R; Lisk, D J; Burgett, D M; Bodyfelt, F W

1988-01-01

As a result of the Chernobyl accident on April 25, 1986, possible radioactive contamination of honey bees and cheese sampled in several areas of the United States were measured. Of bees collected in May and June of 1986 in both Oregon and New York, only those from Oregon showed detectable levels of cesium-134 (T1/2 = 2.05 years), a radionuclide which would have originated from the Chernobyl incident. Cheese produced in Oregon and New York before the accident showed only cesium-137 (T1/2 = 30.23 years) but cheese produced afterwards (May and September, 1986) in Oregon contained cesium-134. Cheese produced in Ohio and California at the time of the accident and thereafter contained only cesium-137. In general, the levels of radioactivity were higher in the West coast samples as compared to those taken in the East. The levels of radioactivity detected were considered to be toxicologically of no consequence.

Optical lattice clock with Strontium atoms; Horloge a reseau optique a atomes de strontium

Energy Technology Data Exchange (ETDEWEB)

Baillard, X

2008-01-15

This thesis presents the latest achievements regarding the optical lattice clock with Strontium atoms developed at LNE-SYRTE. After a review of the different types of optical clocks that are currently under development, we stress on the concept of optical lattice clock which was first imagined for Sr{sup 87} using the {sup 1}S{sub 0} {yields} {sup 3}P{sub 0} transition. We exhibit the features of this atom, in particular the concept of magic wavelength for the trap, and the achievable performances for this kind of clock. The second part presents the experimental aspects, insisting particularly on the ultra-stable laser used for the interrogation of the atoms which is a central part of the experiment. Among the latest improvements, an optical pumping phase and an interrogation phase using a magnetic field have been added in order to refine the evaluation of the Zeeman effect. Finally, the last part presents the experimental results. The last evaluation of the clock using Sr{sup 87} atoms allowed us to reach a frequency accuracy of 2.6*10{sup -15} and a measurement in agreement with the one made at JILA (Tokyo university) at the 10{sup -15} level. On another hand, thanks to recent theoretical proposals, we made a measurement using the bosonic isotope Sr{sup 88} by adapting the experimental setup. This measurement represents the first evaluation for this type of clock, with a frequency accuracy of 7*10{sup -14}. (author)

Electron-stimulated desorption of cesium atoms from cesium layers adsorbed on gold-covered tungsten

Energy Technology Data Exchange (ETDEWEB)

Ageev, V N; Kuznetsov, Yu A; Potekhina, N D, E-mail: kuznets@ms.ioffe.r [A F Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021, St Petersburg (Russian Federation)

2010-03-03

The electron-stimulated desorption (ESD) yields and energy distributions (ED) for neutral cesium atoms have been measured from cesium layers adsorbed on a gold-covered tungsten surface as a function of electron energy, gold film thickness, cesium coverage and substrate temperature. The measurements have been carried out using a time-of-flight method and surface ionization detector in the temperature range 160-300 K. A measurable ESD yield for Cs atoms is observed only after deposition of more than one monolayer of gold and cesium on a tungsten surface at a temperature T = 300 K, which is accompanied by the formation of a CsAu semiconductor film covered with a cesium atom monolayer. The Cs atom ESD yield as a function of incident electron energy has a resonant character and consists of two peaks, the appearance of which depends on both electron energy and substrate temperature. The first peak has an appearance threshold at an electron energy of 57 eV and a substrate temperature of 300 K that is due to Au 5p{sub 3/2} core level excitation in the substrate. The second peak appears at an electron energy of 24 eV and a substrate temperature of 160 K. It is associated with a Cs 5s core level excitation in the Cs adsorbed layer. The Au 5p{sub 3/2} level excitation corresponds to a single broad peak in the ED with a maximum at a kinetic energy of 0.45 eV at a substrate temperature T = 300 K, which is split into two peaks with maxima at kinetic energies of 0.36 and 0.45 eV at a substrate temperature of 160 K, associated with different Cs atom ESD channels. The Cs 5s level excitation leads to an ED for Cs atoms with a maximum at a kinetic energy of approx 0.57 eV which exists only at T < 240 K and low Cs concentrations. The mechanisms for all the Cs atom ESD channels are proposed and compared with the Na atom ESD channels in the Na-Au-W system.

Recovery of cesium

Science.gov (United States)

Izatt, Reed M.; Christensen, James J.; Hawkins, Richard T.

1984-01-01

A process of recovering cesium ions from mixtures of ions containing them and other ions, e.g., a solution of nuclear waste materials, which comprises establishing a separate source phase containing such a mixture of ions, establishing a separate recipient phase, establishing a liquid membrane phase in interfacial contact with said source and recipient phases, said membrane phase containing a ligand, preferably a selected calixarene as depicted in the drawing, maintaining said interfacial contact for a period of time long enough to transport by said ligand a substantial portion of the cesium ion from the source phase to the recipient phase, and recovering the cesium ion from the recipient phase. The separation of the source and recipient phases may be by the membrane phase only, e.g., where these aqueous phases are emulsified as dispersed phases in a continuous membrane phase, or may include a physical barrier as well, e.g., an open-top outer container with an inner open-ended container of smaller cross-section mounted in the outer container with its open bottom end spaced from and above the closed bottom of the outer container so that the membrane phase may fill the outer container to a level above the bottom of the inner container and have floating on its upper surface a source phase and a recipient phase separated by the wall of the inner container as a physical barrier. A preferred solvent for the ligand is a mixture of methylene chloride and carbon tetrachloride.

Cesium-137 retention in irops obtained from various soils

International Nuclear Information System (INIS)

Gulyakin, I.V.; Yudintseva, E.V.; Gorina, L.I.

1974-01-01

A non-station experiment has shown that the accumulation of cesium-137 in a plant yield depends on the type of soil. The highest contents of cesium-137 were found in the yield of plants from soddy-podzolic sandy loam soils, and the lowest- in those from leached chernozem. The accumulation of radiocesium in the yield of the basic produce strongly depended on the plant species. The amount of cesium-137 differed 5- to 7-fold in different crops

Atomic clocks for geodesy

Science.gov (United States)

Mehlstäubler, Tanja E.; Grosche, Gesine; Lisdat, Christian; Schmidt, Piet O.; Denker, Heiner

2018-06-01

We review experimental progress on optical atomic clocks and frequency transfer, and consider the prospects of using these technologies for geodetic measurements. Today, optical atomic frequency standards have reached relative frequency inaccuracies below 10‑17, opening new fields of fundamental and applied research. The dependence of atomic frequencies on the gravitational potential makes atomic clocks ideal candidates for the search for deviations in the predictions of Einstein’s general relativity, tests of modern unifying theories and the development of new gravity field sensors. In this review, we introduce the concepts of optical atomic clocks and present the status of international clock development and comparison. Besides further improvement in stability and accuracy of today’s best clocks, a large effort is put into increasing the reliability and technological readiness for applications outside of specialized laboratories with compact, portable devices. With relative frequency uncertainties of 10‑18, comparisons of optical frequency standards are foreseen to contribute together with satellite and terrestrial data to the precise determination of fundamental height reference systems in geodesy with a resolution at the cm-level. The long-term stability of atomic standards will deliver excellent long-term height references for geodetic measurements and for the modelling and understanding of our Earth.

Measurements of the cesium flow from a surface-plasma H- ion source

International Nuclear Information System (INIS)

Smith, H.V.; Allison, P.W.

1979-01-01

A surface ionization gauge (SIG) was constructed and used to measure the Cs 0 flow rate through the emission slit of a surface-plasma source (SPS) of H - ions with Penning geometry. The equivalent cesium density in the SPS discharge is deduced from these flow measurements. For dc operation the optimum H - current occurs at an equivalent cesium density of approx. 7 x 10 12 cm -3 (corresponding to an average cesium consumption rate of 0.5 mg/h). For pulsed operation the optimum H - current occurs at an equivalent cesium density of approx. 2 x 10 13 cm -3 (1-mg/h average cesium consumption rate). Cesium trapping by the SPS discharge was observed for both dc and pulsed operation. A cesium energy of approx. 0.1 eV is deduced from the observed time of flight to the SIG. In addition to providing information on the physics of the source, the SIG is a useful diagnostic tool for source startup and operation

Circadian rhythms and light responsiveness of mammalian clock gene, Clock and BMAL1, transcripts in the rat retina.

Science.gov (United States)

Namihira, M; Honma, S; Abe, H; Tanahashi, Y; Ikeda, M; Honma, K

1999-08-13

Circadian expression and light-responsiveness of the mammalian clock genes, Clock and BMAL1, in the rat retina were examined by in situ hydbribization under constant darkness. A small but significant daily variation was detected in the Clock transcript level, but not in BMAL1. Light increased the Clock and BMAL1 expressions significantly when examined 60 min after exposure. The light-induced gene expression was phase-dependent for Clock and peaked at ZT2, while rather constant throughout the day for BMAL1. These findings suggest that Clock and BMAL1 play different roles in the generation of circadian rhytm in the retina from those in the suprachiasmatic nucleus. Different roles are also suggested between the two genes in the photic signal transduction in the retina.

Selective extraction of cesium: from compound to process

International Nuclear Information System (INIS)

Simon, N.; Eymard, S.; Tournois, B.; Dozol, J.F.

2000-01-01

Under the French law of 30 December 1991 on nuclear waste management, research is conducted to recover long-lived fission products from high-level radioactive effluents generated by spent fuel reprocessing, in order to destroy them by transmutation or encapsulate them in specific matrices. Cesium extraction with mono and bis-crown calix(4)arenes (Frame 1) is a candidate for process development. These extractants remove cesium from highly acidic or basic pH media even with high salinity. A real raffinate was treated in 1994 in a hot cell to extract cesium with a calix-crown extractant. The success of this one batch experiment confirmed the feasibility of cesium decontamination from high-level liquid waste. It was then decided to develop a process flowchart to extract cesium selectively from high-level raffinate, to be included in the general scheme of long-lived radionuclide partitioning. It was accordingly decided to develop a process based on liquid-liquid extraction and hence optimize a calixarene/diluent solvent according to: - hydraulic properties: density, viscosity, interfacial tension, - chemical criteria: sufficient cesium extraction (depending on the diluent), kinetics, third phase elimination... New mono-crown-calixarenes branched with long aliphatic groups (Frame 2) were designed to be soluble in aliphatic diluents. To prevent third phase formation associated with nitric acid extraction, the addition of modifiers (alcohol, phosphate and amide) in the organic phase was tested (Frame 3). Table 1 shows examples of calixarene/diluent systems suitable for a process flowchart, and Figure 2 provides data on cesium extraction with these new systems. Alongside these improvements, a system based on a modified 1,3-di(n-octyl-oxy)2,4-calix[4]arene crown and a modified diluent was also developed, considering a mixed TPH/NPHE system as the diluent, where TPH (hydrogenated tetra propylene) is a common aliphatic industrial solvent and NPHE is nitrophenyl

Light and the human circadian clock

NARCIS (Netherlands)

Roenneberg, Till; Kantermann, Thomas; Juda, Myriam; Vetter, Céline; Allebrandt, Karla V

2013-01-01

The circadian clock can only reliably fulfil its function if it is stably entrained. Most clocks use the light-dark cycle as environmental signal (zeitgeber) for this active synchronisation. How we think about clock function and entrainment has been strongly influenced by the early concepts of the

A network of (autonomic) clock outputs

NARCIS (Netherlands)

Kalsbeek, A.; Perreau-Lenz, S.; Buijs, R. M.

2006-01-01

The circadian clock in the suprachiasmatic nuclei (SCN) is composed of thousands of oscillator neurons, each dependent on the cell-autonomous action of a defined set of circadian clock genes. A major question is still how these individual oscillators are organized into a biological clock that

THERMIONIC EMISSION ENHANCEMENT FROM CESIUM COATED RHENIUM IN ELECTRIC FIELDS

Energy Technology Data Exchange (ETDEWEB)

de Steese, J. G.; Zollweg, R. J.

1963-04-15

The plasma-anode technique was used to observe anomalously high thermionic emission from a rhenium surface with small cesium coverage, where the work function of the composite surface is greater than the ionization potential of cesium. Data suggest that emission enhancement is caused by increased cesium coverage because of cesiumion trapping near the emitter surface under the influence of an ion-rich sheath. (auth)

Towards Self-Clocked Gated OCDMA Receiver

Science.gov (United States)

Idris, S.; Osadola, T.; Glesk, I.

2013-02-01

A novel incoherent OCDMA receiver with incorporated all-optical clock recovery for self-synchronization of a time gate for the multi access interferences (MAI) suppression and minimizing the effect of data time jitter in incoherent OCDMA system was successfully developed and demonstrated. The solution was implemented and tested in a multiuser environment in an out of the laboratory OCDMA testbed with two-dimensional wavelength-hopping time-spreading coding scheme and OC-48 (2.5 Gbp/s) data rate. The self-clocked all-optical time gate uses SOA-based fibre ring laser optical clock, recovered all-optically from the received OCDMA traffic to control its switching window for cleaning the autocorrelation peak from the surrounding MAI. A wider eye opening was achieved when the all-optically recovered clock from received data was used for synchronization if compared to a static approach with the RF clock being generated by a RF synthesizer. Clean eye diagram was also achieved when recovered clock is used to drive time gating.

Method and article for primary containment of cesium wastes. [DOE patent application

Science.gov (United States)

Angelini, P.; Lackey, W.J.; Stinton, D.P.; Blanco, R.E.; Bond, W.D.; Arnold, W.D. Jr.

1981-09-03

A method for producing a cesium-retentive waste form, characterized by a high degree of compositional stability and mechanical integrity, is provided by subjecting a cesium-loaded zeolite to heat under conditions suitable for stabilizing the zeolite and immobilizing the cesium, and coating said zeolite for sufficient duration within a suitable environment with at least one dense layer of pyrolytic carbon to seal therein said cesium to produce a final, cesium-bearing waste form. Typically, the zolite is stabilized and the cesium immobilized in less than four hours by confinement within an air environment maintained at about 600/sup 0/C. Coatings are thereafter applied by confining the calcined zeolite within a coating environment comprising inert fluidizing and carbon donor gases maintained at 1000/sup 0/C for a suitable duration.

Cesium Toxicity Alters MicroRNA Processing and AGO1 Expressions in Arabidopsis thaliana.

Directory of Open Access Journals (Sweden)

Il Lae Jung

Full Text Available MicroRNAs (miRNAs are short RNA fragments that play important roles in controlled gene silencing, thus regulating many biological processes in plants. Recent studies have indicated that plants modulate miRNAs to sustain their survival in response to a variety of environmental stimuli, such as biotic stresses, cold, drought, nutritional starvation, and toxic heavy metals. Cesium and radio-cesium contaminations have arisen as serious problems that both impede plant growth and enter the food chain through contaminated plants. Many studies have been performed to define plant responses against cesium intoxication. However, the complete profile of miRNAs in plants during cesium intoxication has not been established. Here we show the differential expression of the miRNAs that are mostly down-regulated during cesium intoxication. Furthermore, we found that cesium toxicity disrupts both the processing of pri-miRNAs and AGONOUTE 1 (AGO1-mediated gene silencing. AGO 1 seems to be especially destabilized by cesium toxicity, possibly through a proteolytic regulatory pathway. Our study presents a comprehensive profile of cesium-responsive miRNAs, which is distinct from that of potassium, and suggests two possible mechanisms underlying the cesium toxicity on miRNA metabolism.

A network of (autonomic) clock outputs

NARCIS (Netherlands)

Kalsbeek, A.; Perreau-Lenz, S.; Buijs, R. M.

2006-01-01

The circadian clock in the suprachiasmatic nuclei (SCN) is composed of thousands of oscillator neurons, each of which is dependent on the cell-autonomous action of a defined set of circadian clock genes. A major question is still how these individual oscillators are organized into a biological clock

Effect of cesium seeding on hydrogen negative ion volume production

International Nuclear Information System (INIS)

Bacal, M.; Balghiti-Sube, F. El; Elizarov, L. I.; Tontegode, A. J.

1998-01-01

The effect of cesium vapor partial pressure on the plasma parameters has been studied in the dc hybrid negative ion source ''CAMEMBERT III.'' The cesium vapor pressure was varied up to 10 -5 Torr and was determined by a surface ionization gauge in the absence of the discharge. The negative ion relative density measured by laser photodetachment in the center of the plasma extraction region increases by a factor of four when the plasma is seeded with cesium. However the plasma density and the electron temperature (determined using a cylindrical electrostatic probe) are reduced by the cesium seeding. As a result, the negative ion density goes up by a factor of two at the lowest hydrogen pressure studied. The velocity of the directed negative ion flow to the plasma electrode, determined from two-laser beam photodetachment experiments, appears to be affected by the cesium seeding. The variation of the extracted negative ion and electron currents versus the plasma electrode bias will also be reported for pure hydrogen and cesium seeded plasmas. The cesium seeding leads to a dramatic reduction of the electron component, which is consistent with the reduced electron density and temperature. The negative ion current is enhanced and a goes through a maximum at plasma electrode bias lower than 1 V. These observations lead to the conclusion that the enhancement of pure volume production occurs in this type of plasma. Possible mechanisms for this type of volume process will be discussed

Redistribution of strontium and cesium during alteration of smectite to illite

International Nuclear Information System (INIS)

Ohnuki, Toshihiko; Murakami, Takashi; Sato, Tsutomu; Isobe, Hiroshi

1994-01-01

The redistribution of strontium and cesium during the alteration of smectite to illite has been studied under hydrothermal conditions at 200 C using solutions of 1x10 -4 M Sr and Cs. Two different sorption conditions were applied for the hydrothermal experiments. One was the condition in which strontium and cesium were sorbed by smectite before the hydrothermal experiments (dynamic condition). The other was the condition in which strontium and cesium were sorbed by the alteration products, illite/smectite (I/S) interstratified minerals after the hydrothermal experiments (static condition). The sorption characteristics of strontium and cesium by smectite, I/S interstratified minerals were examined by a sequential extraction method. Most of the strontium was desorbed from smectite and the I/S interstratified minerals with a 1 M KCl solution under both the dynamic and static conditions. Less than 1% of cesium was desorbed from the I/S interstratified minerals with any solution of a 1 M KCl, a 1 M HCl and a 6 M HCl under the dynamic condition, while most of cesium was desorbed with either solution of a 1 M KCl and 1 M HCl from smectite and from the I/S interstratified minerals under the static condition. These suggest that cesium sorbed by smectite changes its sorption characteristic during the alteration process, but strontium does not. Possible sites for more strongly bounded cesium to the I/S interstratified minerals may be at the 'ditrigonal cavity' of adjacent tetrahedral layers. (orig.)

Radiation safety for incineration of radioactive waste contaminated by cesium

International Nuclear Information System (INIS)

Veryuzhs'kij, Yu.V.; Gryin'ko, O.M.; Tokarevs'kij, V.V.

2016-01-01

Problems in the treatment of radioactive waste contaminated by cesium nuclides are considered in the paper. Chornobyl experience in the management of contaminated soil and contaminated forests is analyzed in relation to the accident at Fukushima-1. The minimization of release of cesium aerosols into atmosphere is very important. Radiation influence of inhaling atmosphere aerosols polluted by cesium has damage effect for humans. The research focuses on the treatment of forests contaminated by big volumes of cesium. One of the most important technologies is a pyro-gasification incineration with chemical reactions of cesium paying attention to gas purification problems. Requirements for process, physical and chemical properties of treatment of radioactive waste based on the dry pyro-gasification incineration facilities are considered in the paper together with the discussion of details related to incineration facilities. General similarities and discrepancies in the environmental pollution caused by the accidents at Chornobyl NPP and Fukushima-1 NPP in Japan are analyzed

Biological Clocks & Circadian Rhythms

Science.gov (United States)

Robertson, Laura; Jones, M. Gail

2009-01-01

The study of biological clocks and circadian rhythms is an excellent way to address the inquiry strand in the National Science Education Standards (NSES) (NRC 1996). Students can study these everyday phenomena by designing experiments, gathering and analyzing data, and generating new experiments. As students explore biological clocks and circadian…

Photoionization from the 6p 2P3/2 state of neutral cesium

International Nuclear Information System (INIS)

Haq, S. U.; Nadeem, Ali

2010-01-01

We report the photoionization studies of cesium from the 6p 2 P 3/2 excited state to measure the photoionization cross section at and above the first ionization threshold, oscillator strength of the highly excited transitions, and extension in the Rydberg series. The photoionization cross section at the first ionization threshold is measured as 25 (4) Mb and at excess energies 0.02, 0.04, 0.07, and 0.09 eV as 21, 19, 17, and 16 Mb, respectively. Oscillator strength of the 6p 2 P 3/2 → nd 2 D 5/2 (23 ≤ n ≤ 60) Rydberg transitions has been extracted utilizing the threshold value of photoionization cross section and the recorded nd 2 D 5/2 photoionization spectra.

Strontium-90 and cesium-137 in powdered milk

International Nuclear Information System (INIS)

1977-01-01

Japan Chemical Analysis Center has analysed the strontium-90 and cesium-137 content in powdered milk. The samples were purchased on the open market in Tokyo from the powdered milk producers. The analysis of Strontium-90 and Cesium-137 content was carried out using the method recommended by Science and Technology Agency. (author)

Circadian clocks, epigenetics, and cancer

KAUST Repository

Masri, Selma; Kinouchi, Kenichiro; Sassone-Corsi, Paolo

2015-01-01

The interplay between circadian rhythm and cancer has been suggested for more than a decade based on the observations that shift work and cancer incidence are linked. Accumulating evidence implicates the circadian clock in cancer survival and proliferation pathways. At the molecular level, multiple control mechanisms have been proposed to link circadian transcription and cell-cycle control to tumorigenesis.The circadian gating of the cell cycle and subsequent control of cell proliferation is an area of active investigation. Moreover, the circadian clock is a transcriptional system that is intricately regulated at the epigenetic level. Interestingly, the epigenetic landscape at the level of histone modifications, DNA methylation, and small regulatory RNAs are differentially controlled in cancer cells. This concept raises the possibility that epigenetic control is a common thread linking the clock with cancer, though little scientific evidence is known to date.This review focuses on the link between circadian clock and cancer, and speculates on the possible connections at the epigenetic level that could further link the circadian clock to tumor initiation or progression.

Towards precision measurements of parity violation in cesium: construction of a new experiment using an active detection method by induced emission; Vers des mesures precises de violation de la parite dans le cesium: construction d'une experience nouvelle utilisant une detection active par emission induite

Energy Technology Data Exchange (ETDEWEB)

Jacquier, Ph

1991-04-15

Experiments that show the breaking of parity invariance in atoms can be considered as valid tests of the electroweak theory complementary to those made at high energies. The accurate measurement of the weak charge of a cesium nucleus would bring useful information on radiative corrections. The experiment, that is proposed in this work concerns the strongly forbidden 6S-7S transition of cesium at 540 nm, aims at reaching an accuracy of 1% for this measurement. Cesium atoms are first excited from 6S level to 7S level by a pulsed laser (10 ns) in the presence of a longitudinal electrical field. Then they are detected through induced emission by a probe laser set on 7S-6P(3/2) transition at 1.470 {mu}m. The transitory amplification of the probe beam can be over 100%.The vapour presents a strong plane dichroism due to the alignment of 7S level through the linear polarization of the pumping beam. The weak interaction in the atom makes this alignment tilt by a small angle (1 to 10 micro-radians) that the measurement of the polarization of the amplified probe enables us to determine. In this work we have described the 3 steps we have passed through: the test with a transverse field and a continuous laser beam, the use of a pulsed laser, and the setting of a longitudinal configuration. Preliminary results show that the experiment will be useful and feasible.

Using copper hexacyanoferrate (II) impregnated zeolite for cesium removal from radioactive liquid waste

International Nuclear Information System (INIS)

Fumio, K.; Kenji, M.

1982-01-01

Experiments were performed to obtain fundamental data on cesium ion removal characteristics of metal hexacyanoferrate (II) impregnated zeolite in radioactive liquid waste containing a large amount of sodium sulfate. Copper hexacyanoferrate (II) impregnated zeolite (CuFZ) was prepared and showed a high selectivity for cesium ion. The material was suitable for use in an ion exchange column. This exchanger could selectively and efficiently remove the cesium even if there is 15 wt% Na 2 SO 4 in the solution. Cesium removal ability and stability of CuFZ were excellent over a wide pH range between 1.5 and 10. The cesium ion exchange ability was not influenced by the presence of the alkali metal ions, calcium and magnesium, and carbonate ions even at concentrations 25 times greater than the cesium ion. However, since ammonium ion behaves similarly to cesium ion and interrupts latter ion adsorption, the presence of ammonium ion is not desirable. The CuFZ offers the possibility of separating and removing cesium from liquid wastes produced in facilities handling radioactive materials

Pitfalls of Insulin Pump Clocks

Science.gov (United States)

Reed, Amy J.

2014-01-01

The objective was to raise awareness about the importance of ensuring that insulin pumps internal clocks are set up correctly at all times. This is a very important safety issue because all commercially available insulin pumps are not GPS-enabled (though this is controversial), nor equipped with automatically adjusting internal clocks. Special attention is paid to how basal and bolus dose errors can be introduced by daylight savings time changes, travel across time zones, and am-pm clock errors. Correct setting of insulin pump internal clock is crucial for appropriate insulin delivery. A comprehensive literature review is provided, as are illustrative cases. Incorrect setting can potentially result in incorrect insulin delivery, with potential harmful consequences, if too much or too little insulin is delivered. Daylight saving time changes may not significantly affect basal insulin delivery, given the triviality of the time difference. However, bolus insulin doses can be dramatically affected. Such problems may occur when pump wearers have large variations in their insulin to carb ratio, especially if they forget to change their pump clock in the spring. More worrisome than daylight saving time change is the am-pm clock setting. If this setting is set up incorrectly, both basal rates and bolus doses will be affected. Appropriate insulin delivery through insulin pumps requires correct correlation between dose settings and internal clock time settings. Because insulin pumps are not GPS-enabled or automatically time-adjusting, extra caution should be practiced by patients to ensure correct time settings at all times. Clinicians and diabetes educators should verify the date/time of insulin pumps during patients’ visits, and should remind their patients to always verify these settings. PMID:25355713

Sericitization of illite decreases sorption capabilities for cesium

Science.gov (United States)

Choung, S.; Hwang, J.; Han, W.; Shin, W.

2017-12-01

Release of radioactive cesium (137Cs) to environment occurs through nuclear accidents such as Chernobyl and Fukushima. The concern is that 137Cs has long half-life (t1/2 = 30.2 years) with chemical toxicity and γ-radiation. Sorption techniques are mainly applied to remove 137Cs from aquatic environment. In particular, it has been known well that clay minerals (e.g, illite) are effective and economical sorbents for 137Cs. Illite that was formed by hydrothermal alteration exist with sericite through "sericitization" processes. Although sericite has analogous composition and lattice structure with illite, the sorptive characteristics of illite and sericite for radiocesium could be different. This study evaluated the effects of hydrothermal alteration and weathering process on illite cesium sorption properties. Natural illite samples were collected at Yeongdong area in Korea as the world-largest hydrothermal deposits for illite. The samples were analyzed by XRF, XRD and SEM-EDX to determine mineralogy, chemical compositions and morphological characteristics, and used for batch sorption experiments. The Yeongdong illites predominantly consist of illite, sericite, quartz, and albite. The measured cesium sorption distribution coefficients (Kd,Cs) of reference illite and sericite were approximately 6000 and 400 L kg-1 at low aqueous concentration (Cw 10-7 M), respectively. In contrast, Kd,Cs values for the Yeongdong illite samples ranged from 500 to 4000 L kg-1 at identical concentration. The observed narrow and sharp XRD peak of sericite indicated that the sericite has better crystallinity compared to illite. These experimental results suggested that sericitization processes of illite can decline the sorption capabilities of illite for cesium under various hydrothermal conditions. In particular, weathering experiments raised the cesium sorption to illite, which seems to be related to the increase of preferential sorption sites for cesium through crystallinity destruction

GPS satellite clock determination in case of inter-frequency clock biases for triple-frequency precise point positioning

Science.gov (United States)

Guo, Jiang; Geng, Jianghui

2017-12-01

Significant time-varying inter-frequency clock biases (IFCBs) within GPS observations prevent the application of the legacy L1/L2 ionosphere-free clock products on L5 signals. Conventional approaches overcoming this problem are to estimate L1/L5 ionosphere-free clocks in addition to their L1/L2 counterparts or to compute IFCBs between the L1/L2 and L1/L5 clocks which are later modeled through a harmonic analysis. In contrast, we start from the undifferenced uncombined GNSS model and propose an alternative approach where a second satellite clock parameter dedicated to the L5 signals is estimated along with the legacy L1/L2 clock. In this manner, we do not need to rely on the correlated L1/L2 and L1/L5 ionosphere-free observables which complicates triple-frequency GPS stochastic models, or account for the unfavorable time-varying hardware biases in undifferenced GPS functional models since they can be absorbed by the L5 clocks. An extra advantage over the ionosphere-free model is that external ionosphere constraints can potentially be introduced to improve PPP. With 27 days of triple-frequency GPS data from globally distributed stations, we find that the RMS of the positioning differences between our GPS model and all conventional models is below 1 mm for all east, north and up components, demonstrating the effectiveness of our model in addressing triple-frequency observations and time-varying IFCBs. Moreover, we can combine the L1/L2 and L5 clocks derived from our model to calculate precisely the L1/L5 clocks which in practice only depart from their legacy counterparts by less than 0.006 ns in RMS. Our triple-frequency GPS model proves convenient and efficient in combating time-varying IFCBs and can be generalized to more than three frequency signals for satellite clock determination.

Desorption of radioactive cesium by seawater from the suspended particles in river water.

Science.gov (United States)

Onodera, Masaki; Kirishima, Akira; Nagao, Seiya; Takamiya, Kouichi; Ohtsuki, Tsutomu; Akiyama, Daisuke; Sato, Nobuaki

2017-10-01

In 2011, the accident at the Fukushima-Daiichi nuclear power plant dispersed radioactive cesium throughout the environment, contaminating the land, rivers, and sea. Suspended particles containing clay minerals are the transportation medium for radioactive cesium from rivers to the ocean because cesium is strongly adsorbed between the layers of clay minerals, forming inner sphere complexes. In this study, the adsorption and desorption behaviors of radioactive cesium from suspended clay particles in river water have been investigated. The radioactive cesium adsorption and desorption experiments were performed with two kinds of suspended particulate using a batch method with 137 Cs tracers. In the cesium adsorption treatment performed before the desorption experiments, simulated river water having a total cesium concentration ([ 133+137 Cs + ] total ) of 1.3 nM (10 -9  mol/L) was used. The desorption experiments were mainly conducted at a solid-to-liquid ratio of 0.17 g/L. The desorption agents were natural seawater collected at 10 km north of the Fukushima-Daiichi nuclear power plant, artificial seawater, solutions of NaCl, KCl, NH 4 Cl, and 133 CsCl, and ultrapure water. The desorption behavior, which depends on the preloaded cesium concentration in the suspended particles, was also investigated. Based on the cesium desorption experiments using suspended particles, which contained about 1000 ng/g loaded cesium, the order of cesium desorption ratios for each desorption agent was determined as 1 M NaCl (80%) > 470 mM NaCl (65%) > 1 M KCl (30%) ≈ seawater (natural seawater and Daigo artificial seawater) > 1 M NH 4 Cl (20%) > 1 M 133 CsCl (15%) ≫ ultrapure water (2%). Moreover, an interesting result was obtained: The desorption ratio in the 470 mM NaCl solution was much higher than that in seawater, even though the Na + concentrations were identical. These results indicate that the cesium desorption mechanism is not a simple ion exchange reaction

Room temperature deposition of crystalline indium tin oxide films by cesium-assisted magnetron sputtering

International Nuclear Information System (INIS)

Lee, Deuk Yeon; Baik, Hong-Koo

2008-01-01

Indium tin oxide (ITO) films were deposited on a Si (1 0 0) substrate at room temperature by cesium-assisted magnetron sputtering. Including plasma characteristics, the structural, electrical, and optical properties of deposited films were investigated as a function of cesium partial vapor pressure controlled by cesium reservoir temperature. We calculated the cesium coverage on the target surface showing maximum formation efficiency of negative ions by means of the theoretical model. Cesium addition promotes the formation efficiency of negative ions, which plays important role in enhancing the crystallinity of ITO films. In particular, the plasma density was linearly increased with cesium concentrations. The resultant decrease in specific resistivity and increase in transmittance (82% in the visible region) at optimum cesium concentration (4.24 x 10 -4 Ω cm at 80 deg. C of reservoir temperature) may be due to enhanced crystallinity of ITO films. Excess cesium incorporation into ITO films resulted in amorphization of its microstructure leading to degradation of ITO crystallinity. We discuss the cesium effects based on the growth mechanism of ITO films and the plasma density

Decamp Clock Board Firmware

Energy Technology Data Exchange (ETDEWEB)

Vicente, J. de; Castilla, J.; Martinez, G.

2007-09-27

Decamp (Dark Energy Survey Camera) is a new instrument designed to explore the universe aiming to reveal the nature of Dark Energy. The camera consists of 72 CCDs and 520 Mpixels. The readout electronics of DECam is based on the Monsoon system. Monsoon is a new image acquisition system developed by the NOAO (National Optical Astronomical Observatory) for the new generation of astronomical cameras. The Monsoon system uses three types of boards inserted in a Eurocard format based crate: master control board, acquisition board and clock board. The direct use of the Monsoon system for DECam readout electronics requires nine crates mainly due to the high number of clock boards needed. Unfortunately, the available space for DECam electronics is constrained to four crates at maximum. The major drawback to achieve such desired compaction degree resides in the clock board signal density. This document describes the changes performed at CIEMAT on the programmable logic of the Monsoon clock board aiming to meet such restricted space constraints. (Author) 5 refs.

Decamp Clock Board Firmware

International Nuclear Information System (INIS)

Vicente, J. de; Castilla, J.; Martinez, G.

2007-01-01

Decamp (Dark Energy Survey Camera) is a new instrument designed to explore the universe aiming to reveal the nature of Dark Energy. The camera consists of 72 CCDs and 520 Mpixels. The readout electronics of DECam is based on the Monsoon system. Monsoon is a new image acquisition system developed by the NOAO (National Optical Astronomical Observatory) for the new generation of astronomical cameras. The Monsoon system uses three types of boards inserted in a Eurocard format based crate: master control board, acquisition board and clock board. The direct use of the Monsoon system for DECam readout electronics requires nine crates mainly due to the high number of clock boards needed. Unfortunately, the available space for DECam electronics is constrained to four crates at maximum. The major drawback to achieve such desired compaction degree resides in the clock board signal density. This document describes the changes performed at CIEMAT on the programmable logic of the Monsoon clock board aiming to meet such restricted space constraints. (Author) 5 refs

Cesium transport in Four Mile Creek of the Savannah River Plant

International Nuclear Information System (INIS)

Kiser, D.L.

1979-04-01

The behavior of a large radioactive cesium release to a Savannah River Plant (SRP) stream was examined using a stable cesium release to Four Mile Creek. Measurements following the release show that most of the cesium released was transported downstream; however, sorption and desorption decreased the maximum concentration and increased the travel time and duration, relative to a dye tracer, at sampling stations downstream. The study was made possible by the development of an analytical technique using ammonium molybdophosphate and neutron activation that permitted the measurement of stable cesium concentrations as low as 0.2 μg/L

Myocardial imaging with cesium-130

International Nuclear Information System (INIS)

Harper, P.V.; Resnekov, L.; Stark, V.; Odeh, N.

1984-01-01

Recently comparative studies using nitrogen-13 ammonia and cesium-130 have shown strikingly different myocardial localization patterns in the same subjects with ischemic heart disease. Initial localization of ammonia, an avidly extracted agent, reflects the perfusion pattern in viable myocardial tissue. The myocardial localization of cesium ion, taking place more slowly over 15 to 20 minutes, is apparently much less flow dependent, causing uptake defects shown with ammonia to be largely filled in. Cesium thus appears to provide information on the extent of the viable myocardial mass, apart from perfusion. Cesium-130 (t1/2 30 m) decays by positron emission and electron capture. The whole body radiation absorbed dose, assuming uniform distribution, is 24 mrad/mCi. While abundant production of Cs-130 results from proton bombardment of natural xenon [Xe-130(rho,n)Cs-130] at 15 MeV, small amounts of Cs-129, -131, and -132 are also produced, and enriched Xe-130 is not available. Alternatively almost completely uncontaminated Cs-130 is available by alpha bombardment of natural I-127. Anhydrous sodium iodide is dissolved in acetone and a thin layer (≅20 mg per centimeter squared) is evaporated onto the gold plated tip of the internal target backing which is oscillated vertically to spread out the area upon which the beam is incident. The target surface is inclined 2.5 degrees to the beam giving a power density of about 400 watts per centimeter squared at 100μA which is adequately handled by water cooling. A 30-minute bombardment yields 4 to 5 mCi of Cs-130 which is dissolved directly from the target. This approach appears to offer a new and helpful method for evaluating ischemic heart disease by permitting evaluation of viable myocardial mass

Alternative laser system for cesium magneto-optical trap via optical injection locking to sideband of a 9-GHz current-modulated diode laser.

Science.gov (United States)

Diao, Wenting; He, Jun; Liu, Zhi; Yang, Baodong; Wang, Junmin

2012-03-26

By optical injection of an 852-nm extended-cavity diode laser (master laser) to lock the + 1-order sideband of a ~9-GHz-current-modulated diode laser (slave laser), we generate a pair of phase-locked lasers with a frequency difference up to ~9-GHz for a cesium (Cs) magneto-optical trap (MOT) with convenient tuning capability. For a cesium MOT, the master laser acts as repumping laser, locked to the Cs 6S₁/₂ (F = 3) - 6P₃/₂ (F' = 4) transition. When the + 1-order sideband of the 8.9536-GHz-current-modulated slave laser is optically injection-locked, the carrier operates on the Cs 6S₁/₂ (F = 4) - 6P₃/₂ (F' = 5) cooling cycle transition with -12 MHz detuning and acts as cooling/trapping laser. When carrying a 9.1926-GHz modulation signal, this phase-locked laser system can be applied in the fields of coherent population trapping and coherent manipulation of Cs atomic ground states.

Hydrological Methods can Separate Cesium from Nuclear Waste Saltcake

International Nuclear Information System (INIS)

Brooke, J.N.; Peters, J.F.; Staheli, K.

1999-01-01

Interstitial Fluid Displacement (IFD) is a new and novel method for separating cesium from saltcake waste. Hydrologic modeling of liquid flow through porous saltcake suggests that the cesium, potassium and sodium hydroxide can be separated at high recovery and low volume using IFD.'

A model for radial cesium transport in a fuel pellet

International Nuclear Information System (INIS)

Imoto, Shosuke

1989-01-01

In order to explain the radial redistribution of cesium in an irradiated pellet, a two-step release model is proposed. The first step involves the migration of cesium by atomic diffusion to some channels, such as grain boundaries and cracks, and the second step assumes a thermomigration down along the temperature gradient. Distribution profiles of cesium are obtained by numerical calculation with the present model assuming a constant and spatially uniform birth rate of cesium in the pellet. The result agrees well with the profile observed by micro-gamma scanning for the LWR fuel in the outer region of the pellet but diverges from it at the inner region. Discussion is made on the steady-state model hitherto generally utilized. (orig.)

Accumulation and mobility of cesium in roots of tulip popular seedlings

International Nuclear Information System (INIS)

Cox, T.L.

1975-01-01

Tulip poplar, Liriodendron tulipifera L., seedlings were stem-well tagged with cesium, periodically harvested, and separated into root and shoot compartments to determine seasonal cesium distributions in different root-diameter classes and to delineate element pathways to forest soils. The cesium concentration (μCi/g) in roots less than 0.1 cm in diameter averaged 1.5 and 3.0 times greater than in roots in the 0.5- to 0.1-cm- and 1.0- to 0.5-cm-diameter classes, respectively. Roots contained 24 percent of the seedling pool of cesium in 1 week and about 40 percent in 7 weeks after inoculation. Sixty-five percent of the seedling content was in the root system 8 months after tagging. On an annual basis, roots of the less than 0.5-cm-diameter classes contained an average of 36 percent of the seedling pool (root and shoot) and 72 percent of the root pool of cesium. This is important because small roots constituted a considerable portion of the annual turnover in these root systems. Soil content of cesium (3.37 μCi) at the termination of the study and analysis of treatment effects (aboveground inputs to soil allowed or not allowed) indicated that root processes contributed twice as much cesium to the soil during the study period as the combined aboveground processes contributed

Protection of cesium-antimony photocathodes

International Nuclear Information System (INIS)

Buzulutskov, A.; Breskin, A.; Chechik, R.; Prager, M.; Shefer, E.

1996-06-01

In order to operate gaseous photomultipliers in the visible range it was suggested to protect sensitive photocathodes against contact to air and counting gases by their coating with a thin solid dielectric film. We present data on coating of cesium- antimony photocathodes with alkali-halide (NaI, CsI, CsF, NaF), oxide (SiO) and organic (hexatriacontane, calcium stearate) films. The photoelectron transmission through these films and their protection capability have been studied in detail. Cesium-antimony photocathodes are shown to withstand exposure to considerable doses of oxygen and dry air when coated with Nal films. This opens ways to their operation in gas media. (authors), 11 refs., 6 figs

Internal Clock Drift Estimation in Computer Clusters

Directory of Open Access Journals (Sweden)

Hicham Marouani

2008-01-01

Full Text Available Most computers have several high-resolution timing sources, from the programmable interrupt timer to the cycle counter. Yet, even at a precision of one cycle in ten millions, clocks may drift significantly in a single second at a clock frequency of several GHz. When tracing the low-level system events in computer clusters, such as packet sending or reception, each computer system records its own events using an internal clock. In order to properly understand the global system behavior and performance, as reported by the events recorded on each computer, it is important to estimate precisely the clock differences and drift between the different computers in the system. This article studies the clock precision and stability of several computer systems, with different architectures. It also studies the typical network delay characteristics, since time synchronization algorithms rely on the exchange of network packets and are dependent on the symmetry of the delays. A very precise clock, based on the atomic time provided by the GPS satellite network, was used as a reference to measure clock drifts and network delays. The results obtained are of immediate use to all applications which depend on computer clocks or network time synchronization accuracy.

Cesium-137 as a radiation source

International Nuclear Information System (INIS)

McMullen, W.H.; Sloan, D.P.

1985-01-01

The U.S. Department of Energy (DOE) Byproducts Utilization Program (BUP) seeks to develop and encourage widespread commercial use of defense byproducts that are produced by DOE. Cesium-l37 is one such byproduct that is radioactive and decays with emission of gamma rays. The beneficial use of this radiation to disinfect sewage sludge or disinfest food commodities is actively being pursued by the program. The radiation produced by cesium-l37(Cs-l37) is identical in form to that produced by cobalt-60(Co-60), an isotope that is widely used in commercial applications such as medical product sterilization. The choice of isotope to use depends on several factors ranging from inherent properties of the isotopes to availability and cost. The BUP, although centrally concerned with the beneficial use of Cs-l37, by investigating and assessing the feasibility of various uses hopes to define appropriate circumstances where cesium or cobalt might best be used to accomplish specific objectives. This paper discusses some of the factors that should be considered when evaluating potential uses for isotopic sources

Photoperiodic plasticity in circadian clock neurons in insects

Directory of Open Access Journals (Sweden)

Sakiko eShiga

2013-08-01

Full Text Available Since Bünning’s observation of circadian rhythms and photoperiodism in the runner bean Phaseolus multiflorus in 1936, many studies have shown that photoperiodism is based on the circadian clock system. In insects, involvement of circadian clock genes or neurons has been recently shown in the photoperiodic control of developmental arrests, diapause. Based on molecular and neuronal studies in Drosophila melanogaster, photoperiodic changes have been reported for expression patterns of the circadian clock genes, subcellular distribution of clock proteins, fiber distribution, or the number of plausible clock neurons in different species. Photoperiod sets peaks of per or tim mRNA abundance at lights-off in Sarcophaga crassipalpis, Chymomyza costata and Protophormia terraenovae. Abundance of per and Clock mRNA changes by photoperiod in Pyrrhocoris apterus. Subcellular Per distribution in circadian clock neurons changes with photoperiod in P. terraenovae. Although photoperiodism is not known in Leucophaea maderae, under longer day length, more stomata and longer commissural fibers of circadian clock neurons have been found. These plastic changes in the circadian clock neurons could be an important constituent for photoperiodic clock mechanisms to integrate repetitive photoperiodic information and produce different outputs based on day length.

Electrically switched cesium ion exchange

International Nuclear Information System (INIS)

Lilga, M.A.; Orth, R.J.; Sukamto, J.P.H.; Schwartz, D.T.; Haight, S.M.; Genders, J.D.

1997-04-01

Electrically Switched Ion Exchange (ESIX) is a separation technology being developed as an alternative to conventional ion exchange for removing radionuclides from high-level waste. The ESIX technology, which combines ion exchange and electrochemistry, is geared toward producing electroactive films that are highly selective, regenerable, and long lasting. During the process, ion uptake and elution are controlled directly by modulating the potential of an ion exchange film that has been electrochemically deposited onto a high surface area electrode. This method adds little sodium to the waste stream and minimizes the secondary wastes associated with traditional ion exchange techniques. Development of the ESIX process is well underway for cesium removal using ferrocyanides as the electroactive films. Films having selectivity for perrhenate (a pertechnetate surrogate) over nitrate also have been deposited and tested. A case study for the KE Basin on the Hanford Site was conducted based on the results of the development testing. Engineering design baseline parameters for film deposition, film regeneration, cesium loading, and cesium elution were used for developing a conceptual system. Order of magnitude cost estimates were developed to compare with conventional ion exchange. This case study demonstrated that KE Basin wastewater could be processed continuously with minimal secondary waste and reduced associated disposal costs, as well as lower capital and labor expenditures

Sleep Loss Reduces the DNA-Binding of BMAL1, CLOCK, and NPAS2 to Specific Clock Genes in the Mouse Cerebral Cortex

OpenAIRE

Mongrain, Valerie; La Spada, Francesco; Curie, Thomas; Franken, Paul

2011-01-01

We have previously demonstrated that clock genes contribute to the homeostatic aspect of sleep regulation. Indeed, mutations in some clock genes modify the markers of sleep homeostasis and an increase in homeostatic sleep drive alters clock gene expression in the forebrain. Here, we investigate a possible mechanism by which sleep deprivation (SD) could alter clock gene expression by quantifying DNA-binding of the core-clock transcription factors CLOCK, NPAS2, and BMAL1 to the cis-regulatory s...

Clock gene variation in Tachycineta swallows.

Science.gov (United States)

Dor, Roi; Cooper, Caren B; Lovette, Irby J; Massoni, Viviana; Bulit, Flor; Liljesthrom, Marcela; Winkler, David W

2012-01-01

Many animals use photoperiod cues to synchronize reproduction with environmental conditions and thereby improve their reproductive success. The circadian clock, which creates endogenous behavioral and physiological rhythms typically entrained to photoperiod, is well characterized at the molecular level. Recent work provided evidence for an association between Clock poly-Q length polymorphism and latitude and, within a population, an association with the date of laying and the length of the incubation period. Despite relatively high overall breeding synchrony, the timing of clutch initiation has a large impact on the fitness of swallows in the genus Tachycineta. We compared length polymorphism in the Clock poly-Q region among five populations from five different Tachycineta species that breed across a hemisphere-wide latitudinal gradient (Fig. 1). Clock poly-Q variation was not associated with latitude; however, there was an association between Clock poly-Q allele diversity and the degree of clutch size decline within breeding seasons. We did not find evidence for an association between Clock poly-Q variation and date of clutch initiation in for any of the five Tachycineta species, nor did we found a relationship between incubation duration and Clock genotype. Thus, there is no general association between latitude, breeding phenology, and Clock polymorphism in this clade of closely related birds.Figure 1Photos of Tachycineta swallows that were used in this study: A) T. bicolor from Ithaca, New York, B) T. leucorrhoa from Chascomús, Argentina, C) T. albilinea from Hill Bank, Belize, D) T. meyeni from Puerto Varas, Chile, and E) T. thalassina from Mono Lake, California, Photographers: B: Valentina Ferretti; A, C-E: David Winkler.

Towards precision measurements of parity violation in cesium: construction of a new experiment using an active detection method by induced emission; Vers des mesures precises de violation de la parite dans le cesium: construction d'une experience nouvelle utilisant une detection active par emission induite

Energy Technology Data Exchange (ETDEWEB)

Jacquier, Ph

1991-04-15

Experiments that show the breaking of parity invariance in atoms can be considered as valid tests of the electroweak theory complementary to those made at high energies. The accurate measurement of the weak charge of a cesium nucleus would bring useful information on radiative corrections. The experiment, that is proposed in this work concerns the strongly forbidden 6S-7S transition of cesium at 540 nm, aims at reaching an accuracy of 1% for this measurement. Cesium atoms are first excited from 6S level to 7S level by a pulsed laser (10 ns) in the presence of a longitudinal electrical field. Then they are detected through induced emission by a probe laser set on 7S-6P(3/2) transition at 1.470 {mu}m. The transitory amplification of the probe beam can be over 100%.The vapour presents a strong plane dichroism due to the alignment of 7S level through the linear polarization of the pumping beam. The weak interaction in the atom makes this alignment tilt by a small angle (1 to 10 micro-radians) that the measurement of the polarization of the amplified probe enables us to determine. In this work we have described the 3 steps we have passed through: the test with a transverse field and a continuous laser beam, the use of a pulsed laser, and the setting of a longitudinal configuration. Preliminary results show that the experiment will be useful and feasible.

Ultradian feeding in mice not only affects the peripheral clock in the liver, but also the master clock in the brain

NARCIS (Netherlands)

Sen, Satish; Raingard, Hélène; Dumont, Stéphanie; Kalsbeek, A.; Vuillez, Patrick; Challet, Etienne

2017-01-01

Restricted feeding during the resting period causes pronounced shifts in a number of peripheral clocks, but not the central clock in the suprachiasmatic nucleus (SCN). By contrast, daily caloric restriction impacts also the light-entrained SCN clock, as indicated by shifted oscillations of clock

Cesium removal flow studies using ion exchange

International Nuclear Information System (INIS)

Lee, D.D.; Walker, J.F. Jr.; Taylor, P.A.

1997-01-01

Cesium and strontium radionuclides are a small fraction of the mainly sodium and potassium salts in underground storage tank supernatant at US Department of Energy (DOE) sites at Hanford, Oak Ridge, Savannah River, and Idaho that DOE must remediate. Cesium-137 ( 137 Cs) is the primary gamma radiation source in the dissolved tank waste at these sites, and its removal from the supernatant can reduce the hazard and waste classification of the treated waste reducing the further treatment and disposal costs. Several cesium removal sorbents have been developed by private industry and the US DOE's Office of Science and Technology. Several of these removal technologies have been previously tested in small batch and column tests using simulated and a few actual supernatant under DOE's Environmental Management (EM) programs including the Tanks Focus Area (TFA) and the Efficient Separations and Processing (ESP) Cross-Cutting Program

Catalytic oxidation of silicon by cesium ion bombardment

International Nuclear Information System (INIS)

Souzis, A.E.; Huang, H.; Carr, W.E.; Seidl, M.

1991-01-01

Results for room-temperature oxidation of silicon using cesium ion bombardment and low oxygen exposure are presented. Bombardment with cesium ions is shown to allow oxidation at O 2 pressures orders of magnitude smaller than with noble gas ion bombardment. Oxide layers of up to 30 A in thickness are grown with beam energies ranging from 20--2000 eV, O 2 pressures from 10 -9 to 10 -6 Torr, and total O 2 exposures of 10 0 to 10 4 L. Results are shown to be consistent with models indicating that initial oxidation of silicon is via dissociative chemisorption of O 2 , and that the low work function of the cesium- and oxygen-coated silicon plays the primary role in promoting the oxidation process

Cesium separation using integrated electro-membrane technique

International Nuclear Information System (INIS)

Fors, Patrik; Lillfors-Pintér, Christina; Widestrand, Henrik; Velin, Anna; Bengtsson, Bernt

2014-01-01

Conventional separation technologies such as ion exchange, electro-deionisation and cross flow filtration are not always effective to eliminate nuclides, which are weekly ionised, complexed or hydrated in effluents. Specific nuclide selective absorbers perform well for the treatment of active and contaminated wastewaters but most absorbers generate additional waste while treating high volumes of contaminated water and often show limitations in operating at high flow rates. Electrochemical Ion Exchange (EIX) and EIX in combination with absorbers may offer an alternative solution that overcomes those limitations. This paper reports on the optimization and performance of the integrated technique EIX, for the treatment of low activity effluents that contain cesium and other nuclides. The three-compartment EIX system, which operates with authentic reactor coolant with enhanced nuclide content, indicates high, over 90%, elimination of cesium in a single pass operation mode. With the in-situ and instant ion exchange regeneration, the system successfully reduces the activity from an initial range of 400-2600 Bq/kg to close to detection limit at a velocity of 10-15 cm/min. The applied current density varies between 50-200 mA/cm 2 and the mass balance is close to 100%. During the process, the eliminated cesium and other nuclides are concentrated up to the limits where reverse migration from the concentrated chamber occurs. The concentrate could then be treated with specific absorbents at low flow rates. EIX in combination with cesium-selective ion exchanger CsTreat ® separates the cesium-137 efficiently, but up to now the process does not perform according to EIX principles for the treatment of low grade radioactive wastewaters it rather performs as an irreversible adsorber. The aim with the outcome of the presently ongoing long-term tests is to further support the Best Available Technique Minimizing All Nuclide (BATMAN) projects of Vattenfall NPPs. (author)

An optical clock to go

Science.gov (United States)

Ludlow, Andrew D.

2018-05-01

Bringing next-generation atomic clocks out of the lab is not an easy task, but doing so will unlock many new possibilities. As a crucial first step, a portable atomic clock has now been deployed for relativistic geodesy measurements in the Alps.

Towards precision measurements of parity violation in cesium: construction of a new experiment using an active detection method by induced emission

International Nuclear Information System (INIS)

Jacquier, Ph.

1991-04-01

Experiments that show the breaking of parity invariance in atoms can be considered as valid tests of the electroweak theory complementary to those made at high energies. The accurate measurement of the weak charge of a cesium nucleus would bring useful information on radiative corrections. The experiment, that is proposed in this work concerns the strongly forbidden 6S-7S transition of cesium at 540 nm, aims at reaching an accuracy of 1% for this measurement. Cesium atoms are first excited from 6S level to 7S level by a pulsed laser (10 ns) in the presence of a longitudinal electrical field. Then they are detected through induced emission by a probe laser set on 7S-6P(3/2) transition at 1.470 μm. The transitory amplification of the probe beam can be over 100%.The vapour presents a strong plane dichroism due to the alignment of 7S level through the linear polarization of the pumping beam. The weak interaction in the atom makes this alignment tilt by a small angle (1 to 10 micro-radians) that the measurement of the polarization of the amplified probe enables us to determine. In this work we have described the 3 steps we have passed through: the test with a transverse field and a continuous laser beam, the use of a pulsed laser, and the setting of a longitudinal configuration. Preliminary results show that the experiment will be useful and feasible

Hot demonstration of proposed commercial cesium removal technology

International Nuclear Information System (INIS)

Lee, D.D.; Travis, J.R.; Gibson, M.R.

1997-12-01

This report describes the work done in support of the development of technology for the continuous removal and concentration of radioactive cesium in supernatant from Melton Valley Storage Tanks (MVSTs) at the ORNL site. The primary objective was to test candidate absorbers and ion exchangers under continuous-flow conditions using actual supernatant from the MVSTs. An experimental system contained in a hot-cell facility was constructed to test the materials in columns or modules using the same batch of supernatant to allow comparison on an equal basis. Resorcinol/formaldehyde (RF) resin was evaluated at three flow rates with 50% breakthrough ranges of 35 to 50 column volumes (CV) and also through a series of five loading/elution/regeneration cycles. The results reported here include the cesium loading breakthrough curves, elution curves (when applicable), and operational problems and observations for each material. The comparative evaluations should provide critical data for the selection of the sorbent for the ORNL Cesium Removal Demonstration project. These results will be used to help determine the design parameters for demonstration-scale systems. Such parameters include rates of cesium removal, quantity of resin or sorbent to be used, and elution and regeneration requirements, if applicable

Hardware-assisted software clock synchronization for homogeneous distributed systems

Science.gov (United States)

Ramanathan, P.; Kandlur, Dilip D.; Shin, Kang G.

1990-01-01

A clock synchronization scheme that strikes a balance between hardware and software solutions is proposed. The proposed is a software algorithm that uses minimal additional hardware to achieve reasonably tight synchronization. Unlike other software solutions, the guaranteed worst-case skews can be made insensitive to the maximum variation of message transit delay in the system. The scheme is particularly suitable for large partially connected distributed systems with topologies that support simple point-to-point broadcast algorithms. Examples of such topologies include the hypercube and the mesh interconnection structures.

Processing of visually presented clock times.

Science.gov (United States)

Goolkasian, P; Park, D C

1980-11-01

The encoding and representation of visually presented clock times was investigated in three experiments utilizing a comparative judgment task. Experiment 1 explored the effects of comparing times presented in different formats (clock face, digit, or word), and Experiment 2 examined angular distance effects created by varying positions of the hands on clock faces. In Experiment 3, encoding and processing differences between clock faces and digitally presented times were directly measured. Same/different reactions to digitally presented times were faster than to times presented on a clock face, and this format effect was found to be a result of differences in processing that occurred after encoding. Angular separation also had a limited effect on processing. The findings are interpreted within the framework of theories that refer to the importance of representational codes. The applicability to the data of Bank's semantic-coding theory, Paivio's dual-coding theory, and the levels-of-processing view of memory are discussed.

Fast concentration of dissolved forms of cesium radioisotopes from large seawater samples

International Nuclear Information System (INIS)

Jan Kamenik; Henrieta Dulaiova; Ferdinand Sebesta; Kamila St'astna; Czech Technical University, Prague

2013-01-01

The method developed for cesium concentration from large freshwater samples was tested and adapted for analysis of cesium radionuclides in seawater. Concentration of dissolved forms of cesium in large seawater samples (about 100 L) was performed using composite absorbers AMP-PAN and KNiFC-PAN with ammonium molybdophosphate and potassium–nickel hexacyanoferrate(II) as active components, respectively, and polyacrylonitrile as a binding polymer. A specially designed chromatography column with bed volume (BV) 25 mL allowed fast flow rates of seawater (up to 1,200 BV h -1 ). The recovery yields were determined by ICP-MS analysis of stable cesium added to seawater sample. Both absorbers proved usability for cesium concentration from large seawater samples. KNiFC-PAN material was slightly more effective in cesium concentration from acidified seawater (recovery yield around 93 % for 700 BV h -1 ). This material showed similar efficiency in cesium concentration also from natural seawater. The activity concentrations of 137 Cs determined in seawater from the central Pacific Ocean were 1.5 ± 0.1 and 1.4 ± 0.1 Bq m -3 for an offshore (January 2012) and a coastal (February 2012) locality, respectively, 134 Cs activities were below detection limit ( -3 ). (author)

Cesium-137, a drama recounted

International Nuclear Information System (INIS)

Vieira, Suzane de Alencar

2013-01-01

The radiological accident with Cesium-137, which started on Goiania in 1987, did not stop with the end of radiological contamination and continues in a judicial, scientific and narrative process of identification and recognition of new victims. The drama occupies a central place on the dynamics of radiological event, as it extends its limits, inflects its intensity and updates the event. As a narrative of the event, the ethnography incorporates and brings up to date the drama as an analysis landmark and the description of the theme as it is absorbed by a dramatic process. Cesium-137, a drama recounted is a textual experimentation based on real events and characters picked out from statements reported in various narratives about the radiological accident. (author)

Circadian Clock genes Per2 and clock regulate steroid production, cell proliferation, and luteinizing hormone receptor transcription in ovarian granulosa cells

International Nuclear Information System (INIS)

Shimizu, Takashi; Hirai, Yuko; Murayama, Chiaki; Miyamoto, Akio; Miyazaki, Hitoshi; Miyazaki, Koyomi

2011-01-01

Highlights: → Treatment with Per2 and Clock siRNAs decreased the number of granulosa cells and LHr expression. →Per2 siRNA treatment did not stimulate the production of estradiol and expression of P450arom. → Clock siRNA treatment inhibited the production of estradiol and expression of P450arom mRNA. →Per2 and Clock siRNA treatment increased and unchanged, respectively, progesterone production in FSH-treated granulosa cells. → The expression of StAR mRNA was increased by Per2 siRNA and unchanged by Clock siRNA. -- Abstract: Circadian Clock genes are associated with the estrous cycle in female animals. Treatment with Per2 and Clock siRNAs decreased the number of granulosa cells and LHr expression in follicle-stimulating hormone FSH-treated granulosa cells. Per2 siRNA treatment did not stimulate the production of estradiol and expression of P450arom, whereas Clock siRNA treatment inhibited the production of estradiol and expression of P450arom mRNA. Per2 and Clock siRNA treatment increased and unchanged, respectively, progesterone production in FSH-treated granulosa cells. Similarly, expression of StAR mRNA was increased by Per2 siRNA and unchanged by Clock siRNA. Our data provide a new insight that Per2 and Clock have different action on ovarian granulosa cell functions.

Circadian Clock genes Per2 and clock regulate steroid production, cell proliferation, and luteinizing hormone receptor transcription in ovarian granulosa cells

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Takashi, E-mail: shimizut@obihiro.ac.jp [Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555 (Japan); Hirai, Yuko; Murayama, Chiaki; Miyamoto, Akio [Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555 (Japan); Miyazaki, Hitoshi [Gene Research Center, University of Tsukuba, Tsukuba, Ibaraki 305-8572 (Japan); Miyazaki, Koyomi [Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST) Central 6, 1-1-1, Higashi, Tsukuba, Ibaraki 305-8566 (Japan)

2011-08-19

Highlights: {yields} Treatment with Per2 and Clock siRNAs decreased the number of granulosa cells and LHr expression. {yields}Per2 siRNA treatment did not stimulate the production of estradiol and expression of P450arom. {yields} Clock siRNA treatment inhibited the production of estradiol and expression of P450arom mRNA. {yields}Per2 and Clock siRNA treatment increased and unchanged, respectively, progesterone production in FSH-treated granulosa cells. {yields} The expression of StAR mRNA was increased by Per2 siRNA and unchanged by Clock siRNA. -- Abstract: Circadian Clock genes are associated with the estrous cycle in female animals. Treatment with Per2 and Clock siRNAs decreased the number of granulosa cells and LHr expression in follicle-stimulating hormone FSH-treated granulosa cells. Per2 siRNA treatment did not stimulate the production of estradiol and expression of P450arom, whereas Clock siRNA treatment inhibited the production of estradiol and expression of P450arom mRNA. Per2 and Clock siRNA treatment increased and unchanged, respectively, progesterone production in FSH-treated granulosa cells. Similarly, expression of StAR mRNA was increased by Per2 siRNA and unchanged by Clock siRNA. Our data provide a new insight that Per2 and Clock have different action on ovarian granulosa cell functions.

Separation of cesium from aqueous solutions using alkylated tetraaryl borates

International Nuclear Information System (INIS)

Feldmaier, F.

1991-01-01

The water solubility of cesium tetraaryl borates was lowered by introducing hydrophobic aliphatic side chains into corresponding acid-resistant fluorosubstituted tetraaryl borates. This improved cesium spearability both in precipitation and in extraction from aqueous solutions. (orig.) [de

The Implementation of E1 Clock Recovery

Directory of Open Access Journals (Sweden)

Wang Ziyu

2016-01-01

Full Text Available Clock transform and recovery is of significant importance in microwave TDM service, and it is always extracted from the E1 line data stream in most cases. However, intrinsically uncertain delay and jitter caused by packet transmission of E1 data information, may lead to the indexes of the data recovery clock exceed the clock performance template. Through analysis of the E1 clock indexes and measuring methods, this paper proposes a new clock recovery method. The method employs two buffers, the first RAM is used as a buffer to deduct excess information, and the second FIFO is used as a buffer to recovery the clock and data. The first buffer has a feedback from the second one, and is able to actively respond to changes in the data link and requests from the second one. The test results validate the effectiveness of the method, and the corresponding scheme is also valuable for the other communication systems.

Clock recovery PLL with gated PFD for NRZ ON-OFF Modulated Signals in a retinal implant system.

Science.gov (United States)

Brendler, Christian; Aryan, Naser Pour; Rieger, Viola; Rothermel, Albrecht

2013-01-01

A Clock Recovery Phase Locked Loop with Gated Phase Frequency Detector (GPLL) for NRZ ON-OFF Modulated Signals with low data transmission rates for an inductively powered subretinal implant system is presented. Low data transmission rate leads to a long absence of inductive powering in the system when zeros are transmitted. Consequently there is no possibility to extract any clock in these pauses, thus the digital circuitry can not work any more. Compared to a commonly used PLL for clock extraction, no certain amount of data transitions is needed. This is achieved by having two operating modes. In one mode the GPLL tracks the HF input signal. In the other, the GPLL is an adjustable oscillator oscillating at the last used frequency. The proposed GPLL is fabricated and measured using a 350 nm High Voltage CMOS technology.

Precision spectroscopy on atomic hydrogen

Energy Technology Data Exchange (ETDEWEB)

Parthey, Christian Godehard

2011-12-15

This Thesis reports on three measurements involving the 1S-2S transition in atomic hydrogen and deuterium conducted on a 5.8 K atomic beam. The transition is excited Doppler-free via two counter-propagating photons near 243 nm. The H/D isotope shift has been determined as {delta}{integral}{sub exp}=670 994 334 606(15) Hz. Comparing with the theoretical value for the isotope shift, excluding the leading nuclear size effect, {delta}{integral}{sub th}=670 999 566.90(66)(60) kHz we confirm, twice more accurate, the rms charge radius difference of the deuteron and the proton as left angle r{sup 2} right angle {sub d}- left angle r{sup 2} right angle {sub p}=3.82007(65) fm{sup 2} and the deuteron structure radius r{sub str}=1.97507(78) fm. The frequency ratio of the 1S-2S transition in atomic hydrogen to the cesium ground state hyperfine transition provided by the mobile cesium fountain clock FOM is measured to be {integral}{sub 1S-2S}=2 466 061 413 187 035 (10) Hz which presents a fractional frequency uncertainty of 4.2 x 10{sup -15}. The second absolute frequency measurement of the 1S-2S transition in atomic hydrogen presents the first application of a 900 km fiber link between MPQ and Physikalisch- Technische Bundesanstalt (PTB) in Braunschweig which we have used to calibrate the MPQ hydrogen maser with the stationary cesium fountain clock CSF1 at PTB. With the result of {integral}{sub 1S-2S}=2 466 061 413 187 017 (11) Hz we can put a constraint on the electron Lorentz boost violating coefficients 0.95c{sub (TX)}-0.29c{sub (TY)}-0.08 c{sub (TZ)}=(2.2{+-}1.8) x 10{sup -11} within the framework of minimal standard model extensions. We limit a possible drift of the strong coupling constant through the ratio of magnetic moments at a competitive level ({partial_derivative})/({partial_derivative}t)ln ({mu}{sub Cs})/({mu}{sub B})=-(3.0{+-}1.2) x 10{sup -15} yr{sup -1}.

A model of guarded recursion with clock synchronisation

DEFF Research Database (Denmark)

Bizjak, Aleš; Møgelberg, Rasmus Ejlers

2015-01-01

productivity to be captured in types. The calculus uses clocks representing time streams and clock quantifiers which allow limited and controlled elimination of modalities. The calculus has since been extended to dependent types by Møgelberg. Both works give denotational semantics but no rewrite semantics....... In previous versions of this calculus, different clocks represented separate time streams and clock synchronisation was prohibited. In this paper we show that allowing clock synchronisation is safe by constructing a new model of guarded recursion and clocks. This result will greatly simplify the type theory...... by removing freshness restrictions from typing rules, and is a necessary step towards defining rewrite semantics, and ultimately implementing the calculus....

Improvement of cesium retention in uranium dioxide by additional phases

International Nuclear Information System (INIS)

Gamaury Dubois, S.

1995-01-01

The objective of this study is to improve the cesium retention in nuclear fuel. A bibliographic survey indicates that cesium is rapidly released from uranium dioxide in an accident condition. At temperatures higher than 1500 deg C or in oxidising conditions, our experiments show the difficulty of maintaining cesium inside simulated fuel. Two ternary systems are potentially interesting for the retention of cesium and to reduce the kinetics of release from the fuel: Cs 2 O-Al 2 O 3 -SiO 2 et Cs 2 O-ZrO 2 -SO 2 . The compounds CsAISi 2 O 6 and Cs 2 ZrSi 6 O 15 were studied from 1200 deg C to 2000 deg C by thermogravimetric analysis. The volumetric diffusion coefficients of cesium in these structures, in solid state as well as in liquid one, were measured. A fuel was sintered with (Al 2 O 3 + SiO 2 ) or (ZrO 2 + SiO 2 ) and the intergranular phase was characterized. In the presence of (Al 2 O 3 + SiO 2 ), the sintering is realized at 1610 deg C in H 2 . It is a liquid phase sintering. On the other end, with (ZrO 2 + SiO 2 ), the sintering is a low temperature one in oxidising atmosphere. Finally, cesium containing simulated fuels were produced with these additives. According to the effective diffusion coefficients that were measured, the additives improved the retention of cesium. We have predicted the improvement that could be hoped for in a nuclear reactor, depending on the dispersion of the intergranular additives, the temperature and the degree of oxidation of the UO 2+x . We wait for a factor of 2 for x=0 and more than 8 for x=0.05, up to 2000 deg C. (author). 148 refs., 122 figs., 34 tabs

Co-precipitation and solubility studies of cesium, potassium and sodium tetraphenylborate

International Nuclear Information System (INIS)

Peterson, R.A.

1999-01-01

This report contains the results from a study requested by High Level Waste Division on the co-precipitation and solubility of cesium, potassium, and sodium tetraphenylborate. Co-precipitation of cesium (Cs), potassium (K), and sodium (Na) tetraphenylborate (TPB) helps determine the efficiency of reagent usage in the Small Tank Precipitation Process. This process uses NaTPB to remove cesium from waste by means of precipitation. Previous studies by McCabe suggested that if the sodium ion concentration [Na+] increased the rate at which cesium tetraphenylborate (KTPB) in the presence of high [Na+] (∼5M) appears to produce a mixed solid phase composed of NaTPB and KTPB together in the crystal lattice

Concentrating cesium-137 from seawater using resorcinol-formaldehyde resin for radioecological monitoring

Energy Technology Data Exchange (ETDEWEB)

Egorin, Andrei; Tokar, Eduard; Tutov, Mikhail; Avramenko, Valentin [Institute of Chemistry FEBRAS, Vladivostok (Russian Federation); Far Eastern Federal Univ., Vladivostok (Russian Federation); Palamarchuk, Marina; Marinin, Dmitry [Institute of Chemistry FEBRAS, Vladivostok (Russian Federation)

2017-04-01

A method of preconcentrating cesium-137 from seawater using a resorcinol-formaldehyde resin, which enables one to optimize the ecological monitoring procedure, has been suggested. Studies of sorption of cesium-137 from seawater by resorcinol-formaldehyde resin have been performed, and it has been demonstrated that the cation exchanger is characterized by high selectivity with respect to cesium-137. It was found that the selectivity depended on the temperature of resin solidification and the seawater pH value. The maximal value of the cesium-137 distribution coefficient is equal to 4.1-4.5 x 10{sup 3} cm{sup 3} g{sup -1}. Under dynamic conditions, the ion-exchange resin capacity is 310-910 bed volumes depending on the seawater pH, whereas the efficiency of cesium removal exceeds 95%. The removal of more than 95% of cesium-137 has been attained using 1-3 M solutions of nitric acid: here, the eluate volume was 8-8.4 bed volumes. Application of 3 M solution of nitric acid results in resin degradation with the release of gaseous products.

Measurements of cesium and strontium diffusion in biotite gneiss

International Nuclear Information System (INIS)

Skagius, K.; Neretnieks, I.

1988-01-01

A significant retardation of radionuclides transported by flowing water from an underground repository can be expected if the nuclides are able to diffuse into the water filled micropores in the rock. This diffusion into the pores will also increase the surface available to interactions between the nuclides in the ground water and the rock material, such as sorption. To calculate the retardation, it is necessary to know the sorption properties and the diffusivities in the rock matrix for the radionuclides. Diffusion experiments with cesium and strontium in biotite gneiss samples have been performed. Both the transport of strontium and cesium through rock samples and the concentration profiles of cesium and strontium inside rock samples have been determined. The result shows that diffusion of cesium and strontium occurs in the rock material. A diffusion model has been used to evaluate the diffusivity. Both pore diffusion and surface diffusion had to be included in the model to give good agreement with the experimental data. If surface diffusion is not included in the model, the effective pore diffusivity that gives the best fit to the experimental data is found to be higher than expected from earlier measurement of iodide diffusion in the same type of rock material. This indicates that the diffusion of cesium and strontium (sorbing components) in rock material is caused by both pore diffusion and surface diffusion acting in parallel

Diffusion measurements of cesium and strontium in biotite gneiss

International Nuclear Information System (INIS)

Skagius, K.; Neretnieks, I.

1985-01-01

A significant retardation of radionuclides transported by flowing water from an underground repository can be expected if the nuclides are able to diffuse into the water filled micropores in the rock. This diffusion into the pores will also increase the surface available to interaction between the nuclides in the groundwater and the rock material, such as sorption. To calculate the retardation it is necessary to know the sorption properties and the diffusivities in the rock matrix for the radionuclides. Diffusion experiments with cesium and strontium in biotite gneiss samples have been performed. Both the transport of strontium and cesium through rock samples and the concentration profiles of cesium and strontium inside rock samples have been determined. The result show that diffusion of cesium and strontium occurs in the rock material. A diffusion model has been used to evaluate the diffusivity. Both pore diffusion and surface diffusion had to be included in the model to give good agreement with the experimental data. If surface diffusion is not included in the model, the effective pore diffusivity that gives the best fit to the experimental data is found to be higher than expected from earlier measurements of iodide diffusion in the same type of rock material. This indicates that the diffusion of cesium and strontium (sorbing components) in rock material is caused by both pore diffusion and surface diffusion acting in parallel. (author)

Cesium removal using crystalline silicotitanate. Innovative technology summary report

International Nuclear Information System (INIS)

1999-05-01

Approximately 100 million gallons of radioactive waste is stored in underground storage tanks at the Hanford Site, Idaho National Engineering and Environmental Laboratory (INEEL), Oak Ridge Reservation, and Savannah River Site (SRS). Most of the radioactivity comes from 137 Cs, which emits high-activity gamma radiation. The Cesium Removal System is a modular, transportable, ion-exchange system configured as a compact processing unit. Liquid tank waste flows through columns packed with solid material, called a sorbent, that selectively adsorbs cesium and allows the other materials to pass through. The sorbent is crystalline silicotitanate (CST), an engineered material with a high capacity for sorbing cesium from alkaline wastes. The Cesium Removal System was demonstrated at Oak Ridge using Melton Valley Storage Tank (MVST) waste for feed. Demonstration operations began in September 1996 and were completed during June 1997. Prior to the demonstration, a number of ion-exchange materials were evaluated at Oak Ridge with MVST waste. Also, three ion-exchange materials and three waste types were tested at Hanford. These bench-scale tests were conducted in a hot cell. Hanford's results showed that 300 times less sorbent was used by selecting Ionsiv IE-911 over organic ion-exchange resins for cesium removal. This paper gives a description of the technology and discusses its performance, applications, cost, regulatory and policy issues and lessons learned

Global synchronization of parallel processors using clock pulse width modulation

Science.gov (United States)

Chen, Dong; Ellavsky, Matthew R.; Franke, Ross L.; Gara, Alan; Gooding, Thomas M.; Haring, Rudolf A.; Jeanson, Mark J.; Kopcsay, Gerard V.; Liebsch, Thomas A.; Littrell, Daniel; Ohmacht, Martin; Reed, Don D.; Schenck, Brandon E.; Swetz, Richard A.

2013-04-02

A circuit generates a global clock signal with a pulse width modification to synchronize processors in a parallel computing system. The circuit may include a hardware module and a clock splitter. The hardware module may generate a clock signal and performs a pulse width modification on the clock signal. The pulse width modification changes a pulse width within a clock period in the clock signal. The clock splitter may distribute the pulse width modified clock signal to a plurality of processors in the parallel computing system.

Sorption kinetics of cesium on hydrous titanium dioxide

International Nuclear Information System (INIS)

Altas, Y.; Tel, H.; Yaprak, G.

2003-01-01

Two types of hydrous titanium dioxide possessing different surface properties were prepared and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity were determined in both type sorbents and the maximum adsorption percentage of cesium were observed at pH 12. To elucidate the kinetics of ion-exchange reaction on hydrous titanium dioxide, the isotopic exchange rates of cesium ions between hydrous titanium dioxides and aqueous solutions were measured radiochemically and compared with each other. The diffusion coefficients of Cs + ion for Type1 and Type2 titanium dioxides at pH 12 were calculated as 2.79 x 10 -11 m 2 s -1 and 1.52 x 10 -11 m 2 s -1 , respectively, under particle diffusion controlled conditions. (orig.)

Symmetry breaking nuclear quadrupole coupling tensor orientation for cesium-133 nuclei located in a mirror plane

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Ho; Kim, Jin Eun [Dept. of Chemistry (BK21 plus) and Research Institute of Natural Science, Gyeongsang National University, Jinju (Korea, Republic of); Lee, Kang Yeol [School of Mechanical Engineering, Korea University, Seoul (Korea, Republic of)

2016-11-15

Simultaneous multiple data set fits of all transition peaks of {sup 133}Cs nuclei enabled us to obtain accurate cesium-133 nuclear magnetic resonance (NMR) parameters and Euler angles between the principal axis systems of the chemical shift (CS) and quadrupole coupling (Q) tensors of {sup 133}Cs nuclei in Cs{sub 2}CrO{sub 4} . Although in a previous study of Cs{sub 2}CrO{sub 4} by Power et al. (W. P. Power, S. Mooibroek, R. E. Wasylishen, T. S. Cameron, J. Phys. Chem. 1994, 98, 1552), one central transition was observed for cesium sites 1 and 2 in the {sup 133}Cs NMR spectra and one Euler angle between the CS tensors and Q tensors was obtained as 52° and 7° for cesium sites 1 and 2, respectively, the present single-crystal {sup 133}Cs NMR measurements found two Euler angles (10(2)°, 51.9(1)°, 0°) for site 1 and two central transition peaks for site 2. Three principal components of the CS tensor for Cs1 are oriented along the crystallographic a, b, and c axes, whereas none of the principal components of the Q tensor for Cs1 are oriented along the crystal axes. The principal component V{sub 22} of the Q tensor for Cs1 is tilted 10° from the b axis in the bc plane, and the other two components are not located in the ac plane. Therefore, we have found that the requirement that “the quadrupole coupling tensor for a nucleus located in a mirror plane has one principal axis perpendicular to the mirror plane” cannot be applied to Cs1. On the other hand, δ{sub 11} and V{sub 22} for Cs2 are aligned along the b axis, and the other components of the CS and Q tensors deviate at an angle of 1.4(1)° and 10.1(1)°, respectively, from the a and c axes in the ac plane. A distortion-free powder {sup 133}Cs NMR spectrum of Cs{sub 2}CrO{sub 4} was measured using a solid-state spin echo technique.

Space experiments with high stability clocks

International Nuclear Information System (INIS)

Vessot, R.F.C.

1993-01-01

Modern metrology depends increasingly on the accuracy and frequency stability of atomic clocks. Applications of such high-stability oscillators (or clocks) to experiments performed in space are described and estimates of the precision of these experiments are made in terms of clock performance. Methods using time-correlation to cancel localized disturbances in very long signal paths and a proposed space borne four station VLBI system are described. (TEC). 30 refs., 14 figs., 1 tab

Sorption of cesium in intact rock

International Nuclear Information System (INIS)

Puukko, E.

2014-04-01

The mass distribution coefficient K d is used in performance assessment (PA) to describe sorption of a radionuclide on rock. The R d is determined using crushed rock which causes uncertainty in converting the R d values to K d values for intact rock. This work describes a method to determine the equilibrium of sorption on intact rock. The rock types of the planned Olkiluoto waste disposal site were T-series mica gneiss (T-MGN), T-series tonalite granodiorite granite gneiss (T-TGG), P-series tonalite granodiorite granite gneiss (P-TGG) and pegmatitic granite (PGR). These rocks contain different amount of biotite which is the main sorbing mineral. The sorption of cesium on intact rock slices was studied by applying an electrical field to speed up migration of cesium into the rock. Cesium is in the solution as a noncomplex cation Cs + and it is sorbed by ion exchange. The tracer used in the experiments was 134 Cs. The experimental sorption on the intact rock is compared with values calculated using the in house cation exchange sorption model (HYRL model) in PHREEQC program. The observed sorption on T-MGN and T-TGG rocks was close to the calculated values. Two PGR samples were from a depth of 70 m and three samples were from a depth of 150 m. Cesium sorbed more than predicted on the two 70 m PGR samples. The sorption of Cs on the three 150 m PGR samples was small which was consistent with the calculations. The pegmatitic granite PGR has the smallest content of biotite of the four rock types. In the case of P-TGG rock the observed values of sorption were only half of the calculated values. Two kind of slices were cut from P-TGG drill core. The slices were against and to the direction of the foliation of the biotite rims. The sorption of cesium on P-TGG rock was same in both cases. The results indicated that there was no effect of the directions of the electric field and the foliation of biotite in the P-TGG rock. (orig.)

Test procedures and instructions for Hanford tank waste supernatant cesium removal

Energy Technology Data Exchange (ETDEWEB)

Hendrickson, D.W., Westinghouse Hanford

1996-05-31

This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test using Hanford Double-Shell Slurry Feed supernatant liquor from tank 251-AW-101 in a bench-scale column.Cesium sorbents to be tested include resorcinol-formaldehyde resin and crystalline silicotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-022, Hanford Tank Waste Supernatant Cesium Removal Test Plan.

Co-precipitation and solubility studies of cesium, potassium and sodium tetraphenylborate

International Nuclear Information System (INIS)

Peterson, R.A.

2000-01-01

This report contains the results from a study requested by High Level Waste on the co-precipitation and solubility of cesium, potassium, and sodium tetraphenylborate. Co-precipitation of cesium (Cs), potassium (K), and sodium (Na) tetraphenylborate (TPB) helps determine the efficiency of reagent usage in the Small Tank Precipitation Process. This process uses NaTPB to remove cesium from waste by means of precipitation. Previous studies by McCabe suggested that if the sodium ion concentration [Na + ] increased the rate at which cesium tetraphenylborate (CsTPB) precipitates also increases. Serkiz also demonstrated that the precipitation of potassium tetraphenylborate (KTPB) in the presence of high [Na + ] (∼5M) appears to produce a mixed solid phase composed of NaTPB and KTPB together in the crystal lattice. In the crystallographic structure of these three tetraphenylborate salts (Cs,K,NaTPB), the tetraphenylborate ion dominates the size of the crystals. Also, note that the three crystals have nearly identical structures with the exception of two additional peaks in the cesium pattern. Given these similarities, TPB precipitation in the presence of Na + , Cs + and K + likely produces an impure isomorphic crystalline mixture of CsTPB, KTPB and NaTPB. The authors speculate that the primary crystalline structure resembles that of KTPB with NaTPB and CsTPB mixed throughout the crystal structure. The precipitation of NaTPB makes some of the anticipated excess tetraphenylborate relatively unavailable for precipitation of cesium. Thus, the amount of excess tetraphenylborate required to completely precipitate all of the potassium and cesium may increase significantly

Potassium effect on cesium 137 behaviour in natural waters of contaminated regions (Belarus)

International Nuclear Information System (INIS)

Kudel'skij, A.V.; Pashkevich, V.I.; Ovsyannikova, S.V.; Petrovich, A.A.; Smit, D.T.

1998-01-01

Very close relationships between cesium 137 activity of water objects (soil solutions, bog and lake water) and their stable potassium contents have been revealed in the contaminated area in south-eastern Belarus. It was revealed the increase of cesium 137 activity in soil solutions and bog ecosystems proportionally with the increase of potassium content. The exponential dependence of cesium 137 activity of fish production was similar to reverse. The coefficient of cesium 137 accumulation in plants was estimated to be reverse connected with the potassium content in soils. So an universal character of these relations and their specificity are of interest when elaborating countermeasures for reducing population dose loads due to cesium 137 water migration

Geodesy and metrology with a transportable optical clock

Science.gov (United States)

Grotti, Jacopo; Koller, Silvio; Vogt, Stefan; Häfner, Sebastian; Sterr, Uwe; Lisdat, Christian; Denker, Heiner; Voigt, Christian; Timmen, Ludger; Rolland, Antoine; Baynes, Fred N.; Margolis, Helen S.; Zampaolo, Michel; Thoumany, Pierre; Pizzocaro, Marco; Rauf, Benjamin; Bregolin, Filippo; Tampellini, Anna; Barbieri, Piero; Zucco, Massimo; Costanzo, Giovanni A.; Clivati, Cecilia; Levi, Filippo; Calonico, Davide

2018-05-01

Optical atomic clocks, due to their unprecedented stability1-3 and uncertainty3-6, are already being used to test physical theories7,8 and herald a revision of the International System of Units9,10. However, to unlock their potential for cross-disciplinary applications such as relativistic geodesy11, a major challenge remains: their transformation from highly specialized instruments restricted to national metrology laboratories into flexible devices deployable in different locations12-14. Here, we report the first field measurement campaign with a transportable 87Sr optical lattice clock12. We use it to determine the gravity potential difference between the middle of a mountain and a location 90 km away, exploiting both local and remote clock comparisons to eliminate potential clock errors. A local comparison with a 171Yb lattice clock15 also serves as an important check on the international consistency of independently developed optical clocks. This campaign demonstrates the exciting prospects for transportable optical clocks.

Algorithmic-Reducibility = Renormalization-Group Fixed-Points; ``Noise''-Induced Phase-Transitions (NITs) to Accelerate Algorithmics (``NIT-Picking'') Replacing CRUTCHES!!!: Gauss Modular/Clock-Arithmetic Congruences = Signal X Noise PRODUCTS..

Science.gov (United States)

Siegel, J.; Siegel, Edward Carl-Ludwig

2011-03-01

Cook-Levin computational-"complexity"(C-C) algorithmic-equivalence reduction-theorem reducibility equivalence to renormalization-(semi)-group phase-transitions critical-phenomena statistical-physics universality-classes fixed-points, is exploited with Gauss modular/clock-arithmetic/model congruences = signal X noise PRODUCT reinterpretation. Siegel-Baez FUZZYICS=CATEGORYICS(SON of ``TRIZ''): Category-Semantics(C-S) tabular list-format truth-table matrix analytics predicts and implements "noise"-induced phase-transitions (NITs) to accelerate versus to decelerate Harel [Algorithmics(1987)]-Sipser[Intro. Theory Computation(1997) algorithmic C-C: "NIT-picking" to optimize optimization-problems optimally(OOPO). Versus iso-"noise" power-spectrum quantitative-only amplitude/magnitude-only variation stochastic-resonance, this "NIT-picking" is "noise" power-spectrum QUALitative-type variation via quantitative critical-exponents variation. Computer-"science" algorithmic C-C models: Turing-machine, finite-state-models/automata, are identified as early-days once-workable but NOW ONLY LIMITING CRUTCHES IMPEDING latter-days new-insights!!!

Measurement of low levels of cesium-137 in water

International Nuclear Information System (INIS)

Milham, R.C.; Kantelo, M.V.

1984-10-01

Large volume water sampling systems were developed to measure very low levels of cesium-137 in river water and in finished water from water treatment plants. Three hundred to six hundred liters of filtered water are passed through the inorganic ion exchanger potassium cobalti-ferrocyanide to remove greater than 90% of the cesium. Measurement of cesium-137 by gamma ray spectrometry results in a sensitivity of 0.001 pCi/L. Portable as well as stationary samplers were developed to encompass a variety of applications. Results of a one year study of water from the Savannah River and from water treatment plants processing Savannah River water are presented. 3 references, 7 figures

Measurement of cesium emissions during the vitrification of simulated high level radioactive waste

International Nuclear Information System (INIS)

Zamecnik, J.R.; Miller, D.H.; Carter, J.T.

1992-01-01

In the Defense Waste Processing Facility at the Savannah River Site, it is desired to eliminate a startup test that would involve adding small amounts of radioactive cesium-137 to simulated high-level waste. In order to eliminate this test, a reliable method for measuring non-radioactive cesium in the offgas system from the glass melter is required. From a pilot scale melter system, offgas particulate samples were taken on filter paper media and analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The ICPMS method proved to be sufficiently sensitive to measure cesium quantities as low as 0.135 μg, with the sensitivity being limited by the background cesium present in the filter paper. Typical particulate loadings ranged from 800 μg of cesium. This sensitivity allowed determination of cesium decontamination factors for four of the five major components of the offgas system. The decontamination factors measured experimentally compared favorably with the process design basis values

Cesium-137 inventory of the undisturbed soil areas in the Londrina Region, Parana, Brazil

International Nuclear Information System (INIS)

Andrello, Avacir C.; Appoloni, Carlos Roberto

2005-01-01

Cesium-137 is an artificial radionuclide introduced in the environment through the radioactive fallout of the superficial tests of nuclear weapons. The cesium-137 deposition occurred to middles of the 1980-decade and, due to the Chernobyl accident, great part of Europe had a additional fallout of cesium-137. The contaminations of this accident do not have reached Southern Hemisphere. Cesium-137 is an alkaline metal, high electropositive, that in contact with the soil is strongly adsorbed to the clay in the FES (Frayed Edge Sites) and RES (Regular Edge Sites) positions, and it movement by chemical processes in the soil is insignificant. Because of this, cesium-137 became a good soil marker, and its movement is related to the soil movement particles, so that the cesium-137 have been used in the study of the soil redistribution processes, as a tool of quantifying the rates of soil losses and gain. To use this methodology, it is necessary the knowledge of the reference inventory of cesium-137, that is given as function of the total concentration of cesium-137 deposited in an area by the radioactive fallout. If a sampling point presents less cesium-137 than the reference inventory, this point is considered a point with soil loss; otherwise, the point is considered a point with soil deposition. To evaluate the cesium-137 inventory in the Londrina region, four areas of the undisturbed soil were sampling in grid of 3x3, with a distance of 9 meters among the points. Of these four sampling areas, three areas were of native forest (labeled Mata1, Mata2 and Mata UEL), and one was a pasture area. Cesium-137 inventory was 223 ± 41 Bq m -2 , 240 ± 65 Bq m -2 and 305 ± 36 Bq m -2 for Mata UEL, Mata1 and Mata2, respectively, and of 211 ± 28 Bq m -2 for the native pasture. Considering the deviation in each value, it is not possible to conclude that there are differences among the values of cesium-137 inventory, so that the average reference inventory of cesium-137 for the

Sound Clocks and Sonic Relativity

Science.gov (United States)

Todd, Scott L.; Menicucci, Nicolas C.

2017-10-01

Sound propagation within certain non-relativistic condensed matter models obeys a relativistic wave equation despite such systems admitting entirely non-relativistic descriptions. A natural question that arises upon consideration of this is, "do devices exist that will experience the relativity in these systems?" We describe a thought experiment in which `acoustic observers' possess devices called sound clocks that can be connected to form chains. Careful investigation shows that appropriately constructed chains of stationary and moving sound clocks are perceived by observers on the other chain as undergoing the relativistic phenomena of length contraction and time dilation by the Lorentz factor, γ , with c the speed of sound. Sound clocks within moving chains actually tick less frequently than stationary ones and must be separated by a shorter distance than when stationary to satisfy simultaneity conditions. Stationary sound clocks appear to be length contracted and time dilated to moving observers due to their misunderstanding of their own state of motion with respect to the laboratory. Observers restricted to using sound clocks describe a universe kinematically consistent with the theory of special relativity, despite the preferred frame of their universe in the laboratory. Such devices show promise in further probing analogue relativity models, for example in investigating phenomena that require careful consideration of the proper time elapsed for observers.

Microbial accumulation of uranium, radium, and cesium

International Nuclear Information System (INIS)

Strandberg, G.W.; Shumate, S.E. II; Parrott, J.R. Jr.; North, S.E.

1981-05-01

Diverse microbial species varied considerably in their ability to accumulate uranium, cesium, and radium. Mechanistic differences in uranium uptake by Saccharomyces cerevisiae and Pseudomonas aeruginosa were indicated. S. serevisiae exhibited a slow (hours) surface accumulation of uranium which was subject to environmental factors, while P. aeruginosa accumulated uranium rapidly (minutes) as dense intracellular deposits and did not appear to be affected by environmental parameters. Metabolism was not required for uranium uptake by either organism. Cesium and radium were concentrated to a considerably lesser extent than uranium by the several species tested

Positron annihilation and pressure-induced electronic s-d transition

International Nuclear Information System (INIS)

McMahan, A.K.; Skriver, H.L.

1985-06-01

The polycrystalline, partial annihilation rates for positrons in compressed cesium have been calculated using the linear muffin-tin orbitals method. These results suggest that the pressure-induced electronic s-d transition in Cs should be directly observable by momentum sensitive positron annihilation experiments

Adsorption of Radioactive Cesium to Illite-Sericite Mixed Clays

Science.gov (United States)

Hwang, J. H.; Choung, S.; Park, C. S.; Jeon, S.; Han, J. H.; Han, W. S.

2016-12-01

Once radioactive cesium is released into aquatic environments through nuclear accidents such as Chernobyl and Fukushima, it is harmful to human and ecological system for a long time (t1/2 = 30.2 years) because of its chemical toxicity and γ-radiation. Sorption mechanism is mainly applied to remove the cesium from aquatic environments. Illite is one of effective sorbent, considering economical cost for remediation. Although natural illite is typically produced as a mixture with sericite formed by phyllic alteration in hydrothermal ore deposits, the effects of illite-sericite mixed clays on cesium sorption was rarely studied. This study evaluated the sorption properties of cesium to natural illite collected at Yeongdong in Korea as the world-largest illite producing areas (termed "Yeongdong illite"). The illite samples were analyzed by XRF, XRD, FT-IR and SEM-EDX to determine mineralogy, chemical composition, and morphological characteristics, and used for batch sorption experiments. Most of "Yeongdong illite" samples predominantly consist of sericite, quartz, albite, plagioclase feldspar and with minor illite. Cesium sorption distribution coefficients (Kd,Cs) of various "Yeongdong illite" samples ranged from 500 to 4000 L/kg at low aqueous concentration (Cw 10-7 M). Considering Kd,Cs values were 400 and 6000 using reference sericite and illite materials, respectively, in this study, these results suggested that high contents of sericite significantly affect the decrease of sorption capabilities for radiocesium by natural illite (i.e., illite-sericite mixed clay).

The Boulder measurement of parity violation and an anapole moment in cesium

International Nuclear Information System (INIS)

Cho, D.; Wood, C.S.; Bennett, S.C.; Roberts, J.L.; Masterson, B.P.; Tanner, C.E.; Wieman, C.E.

1999-01-01

The amplitude of the parity-nonconserving transition between the 6S and 7S states of cesium was precisely measured with the use of a spin-polarized atomic beam. This measurement gives Im(E1 pnc )/β = - 1.5935(56) milli-volts per centimeter and provides an improved test of the standard model at low energy, including a value for the S parameter of -1.3(3) exp (11) theory . The nuclear spin-dependent contributions was 0.077(11) milli-volts per centimeter, this contribution is a manifestation of parity violation in atomic nuclei and is a measurement of the long-sought anapole moment. (authors)

High voltage holding in the negative ion sources with cesium deposition

Energy Technology Data Exchange (ETDEWEB)

Belchenko, Yu.; Abdrashitov, G.; Ivanov, A.; Sanin, A.; Sotnikov, O., E-mail: O.Z.Sotnikov@inp.nsk.su [Budker Institute of Nuclear Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk (Russian Federation)

2016-02-15

High voltage holding of the large surface-plasma negative ion source with cesium deposition was studied. It was found that heating of ion-optical system electrodes to temperature >100 °C facilitates the source conditioning by high voltage pulses in vacuum and by beam shots. The procedure of electrode conditioning and the data on high-voltage holding in the negative ion source with small cesium seed are described. The mechanism of high voltage holding improvement by depletion of cesium coverage is discussed.

Sleep loss reduces the DNA-binding of BMAL1, CLOCK, and NPAS2 to specific clock genes in the mouse cerebral cortex.

Directory of Open Access Journals (Sweden)

Valérie Mongrain

Full Text Available We have previously demonstrated that clock genes contribute to the homeostatic aspect of sleep regulation. Indeed, mutations in some clock genes modify the markers of sleep homeostasis and an increase in homeostatic sleep drive alters clock gene expression in the forebrain. Here, we investigate a possible mechanism by which sleep deprivation (SD could alter clock gene expression by quantifying DNA-binding of the core-clock transcription factors CLOCK, NPAS2, and BMAL1 to the cis-regulatory sequences of target clock genes in mice. Using chromatin immunoprecipitation (ChIP, we first showed that, as reported for the liver, DNA-binding of CLOCK and BMAL1 to target clock genes changes in function of time-of-day in the cerebral cortex. Tissue extracts were collected at ZT0 (light onset, -6, -12, and -18, and DNA enrichment of E-box or E'-box containing sequences was measured by qPCR. CLOCK and BMAL1 binding to Cry1, Dbp, Per1, and Per2 depended on time-of-day, with maximum values reached at around ZT6. We then observed that SD, performed between ZT0 and -6, significantly decreased DNA-binding of CLOCK and BMAL1 to Dbp, consistent with the observed decrease in Dbp mRNA levels after SD. The DNA-binding of NPAS2 and BMAL1 to Per2 was also decreased by SD, although SD is known to increase Per2 expression in the cortex. DNA-binding to Per1 and Cry1 was not affected by SD. Our results show that the sleep-wake history can affect the clock molecular machinery directly at the level of chromatin binding thereby altering the cortical expression of Dbp and Per2 and likely other targets. Although the precise dynamics of the relationship between DNA-binding and mRNA expression, especially for Per2, remains elusive, the results also suggest that part of the reported circadian changes in DNA-binding of core clock components in tissues peripheral to the suprachiasmatic nuclei could, in fact, be sleep-wake driven.

Sleep loss reduces the DNA-binding of BMAL1, CLOCK, and NPAS2 to specific clock genes in the mouse cerebral cortex.

Science.gov (United States)

Mongrain, Valérie; La Spada, Francesco; Curie, Thomas; Franken, Paul

2011-01-01

We have previously demonstrated that clock genes contribute to the homeostatic aspect of sleep regulation. Indeed, mutations in some clock genes modify the markers of sleep homeostasis and an increase in homeostatic sleep drive alters clock gene expression in the forebrain. Here, we investigate a possible mechanism by which sleep deprivation (SD) could alter clock gene expression by quantifying DNA-binding of the core-clock transcription factors CLOCK, NPAS2, and BMAL1 to the cis-regulatory sequences of target clock genes in mice. Using chromatin immunoprecipitation (ChIP), we first showed that, as reported for the liver, DNA-binding of CLOCK and BMAL1 to target clock genes changes in function of time-of-day in the cerebral cortex. Tissue extracts were collected at ZT0 (light onset), -6, -12, and -18, and DNA enrichment of E-box or E'-box containing sequences was measured by qPCR. CLOCK and BMAL1 binding to Cry1, Dbp, Per1, and Per2 depended on time-of-day, with maximum values reached at around ZT6. We then observed that SD, performed between ZT0 and -6, significantly decreased DNA-binding of CLOCK and BMAL1 to Dbp, consistent with the observed decrease in Dbp mRNA levels after SD. The DNA-binding of NPAS2 and BMAL1 to Per2 was also decreased by SD, although SD is known to increase Per2 expression in the cortex. DNA-binding to Per1 and Cry1 was not affected by SD. Our results show that the sleep-wake history can affect the clock molecular machinery directly at the level of chromatin binding thereby altering the cortical expression of Dbp and Per2 and likely other targets. Although the precise dynamics of the relationship between DNA-binding and mRNA expression, especially for Per2, remains elusive, the results also suggest that part of the reported circadian changes in DNA-binding of core clock components in tissues peripheral to the suprachiasmatic nuclei could, in fact, be sleep-wake driven.

Novel transcriptional networks regulated by CLOCK in human neurons.

Science.gov (United States)

Fontenot, Miles R; Berto, Stefano; Liu, Yuxiang; Werthmann, Gordon; Douglas, Connor; Usui, Noriyoshi; Gleason, Kelly; Tamminga, Carol A; Takahashi, Joseph S; Konopka, Genevieve

2017-11-01

The molecular mechanisms underlying human brain evolution are not fully understood; however, previous work suggested that expression of the transcription factor CLOCK in the human cortex might be relevant to human cognition and disease. In this study, we investigated this novel transcriptional role for CLOCK in human neurons by performing chromatin immunoprecipitation sequencing for endogenous CLOCK in adult neocortices and RNA sequencing following CLOCK knockdown in differentiated human neurons in vitro. These data suggested that CLOCK regulates the expression of genes involved in neuronal migration, and a functional assay showed that CLOCK knockdown increased neuronal migratory distance. Furthermore, dysregulation of CLOCK disrupts coexpressed networks of genes implicated in neuropsychiatric disorders, and the expression of these networks is driven by hub genes with human-specific patterns of expression. These data support a role for CLOCK-regulated transcriptional cascades involved in human brain evolution and function. © 2017 Fontenot et al.; Published by Cold Spring Harbor Laboratory Press.

Dosage of cesium 137 in radioactive wastes by the application of sodium tetraphenylborate; Dosage du cesium 137 dans les effluents radioactifs par le tetraphenylborate de sodium

Energy Technology Data Exchange (ETDEWEB)

Testemale, G; Girault, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-07-01

A simple technique of the dosage of {sup 137}Cs has been developed. The technique consists in the formation of cesium tetraphenyl borate, followed by a double extraction with isoamyl acetate, and washing of the organic phase. The counting of known parts of the cesium solution assaying of its purity by {gamma} spectrometry enable the determination of the {sup 137}Cs. The yield is about 98 per cent. (authors) [French] Une technique simple du dosage du {sup 137}Cs a ete mise au point. Elle consiste en une double extraction du tetraphenylborate de cesium forme par l'acetate d'isoamyle suivie d'un lavage de la phase organique. Des comptages sur des parties aliquotes de la solution de cesium et un controle de purete par spectrometrie {gamma} permettent la determination de cet element. Rendement: environ 98 pour cent. (auteurs)

Removal of radioactive cesium from soil by ammonium citrate solution and ionic liquid

International Nuclear Information System (INIS)

Ishiwata, Shunji; Kitakouji, Manabu; Taga, Atsushi; Ogata, Fumihiko; Ouchi, Hidekazu; Yamanishi, Hirokuni; Inagaki, Masayo

2015-01-01

Radioactive cesium has strongly bound soil as time proceeded, which could not be cleaved in mild condition. We have found that serial treatment of ammonium citrate solution and ionic liquid removed radioactive cesium from soil effectively. The sequence of the treatment is crucial, since inverse serial treatment or mixture of two kinds of solution did not show such an effect, which suggested that ammonium citrate unlocked trapped cesium in soil and ionic liquid solved it. We also found that repeating serial treatment and prolonged treatment time additively removed cesium from soil. (author)

Cesium immobilization into potassium magnesium phosphate matrix

International Nuclear Information System (INIS)

Sayenko, S.Y.; Shkuropatenko, V.A.; Bereznyak, O.P.; Hodyreva, Y.S.; Tarasov, R.V.; Virych, V.D.; Ulybkina, E.A.; Pylypenko, O.V.; Kholomeev, G.O.; Zykova, A.V.; Wagh, Arun S.

2017-01-01

The possibility of isomorphous substitution of potassium ions by cesium ions in the structure of potassium magnesium phosphate KMgPO 4 centred dot 6H 2 O (PMP) was shown. It was established, that the Cs included into the PMP matrix does not transfer to the environment during high temperatures heating process (1176 deg C, 3 hours). Analysis of the IR absorption spectrum of the PMP sample has demonstrated that an increase in the amount of additive of the cesium chloride resulted in the shift of the main bands in the spectrum to the low-frequency region with average shift value 10 cm -1 , which indicates the strengthening of bonds in the crystal lattice of matter. The calculated degree of substitution of potassium by cesium during energy release process in the PMP matrix at the level of vitrified high level wastes is about 4%, i. e. the PMP matrix should correspond to the formula K 0.96 Cs 0.04 MgPO 4 centred dot 6H 2 O.

Pilot unit for cesium-137 separation

International Nuclear Information System (INIS)

Raggenbass, A.; Quesney, M.; Fradin, J.; Dufrene, J.

1958-01-01

Users of radiation are becoming increasingly interested in cesium-137. At the same time the starting up of the industrial plant at Marcoule will make available in the near future large stocks of fission products which should be made use of as quickly as possible. The installation described is a pilot plant for cesium-137 production which should make it possible: - to verify the chemical method on actual solutions of fission products, by treating about 100 curies of 137 Cs by operation, - to obtain technical information on the chemical equipment (tele-commands, corrosion, maintenance, etc...), - to obtain 137 Cs in sufficient quantity to perfect the technique of the manufacture of sealed sources. (author) [fr

High-current negative hydrogen ion beam production in a cesium-injected multicusp source

International Nuclear Information System (INIS)

Takeiri, Y.; Tsumori, K.; Kaneko, O.

1997-01-01

A high-current negative hydrogen ion source has been developed, where 16.2 A of the H - current was obtained with a current density of 31 mA/cm 2 . The ion source is a multicusp source with a magnetic filter for negative ion production, and cesium vapor is injected into the arc chamber, leading to enhancement of the negative ion yields. The cesium-injection effects are discussed, based on the experimental observations. Although the surface production of the negative ions on the cesium-covered plasma grid is thought to be a dominant mechanism of the H - current enhancement, the cesium effects in the plasma volume, such as the cesium ionization and the electron cooling, are observed, and could contribute to the improved operation of the negative ion source. (author)

Naming analog clocks conceptually facilitates naming digital clocks

NARCIS (Netherlands)

Meeuwissen, M.H.W.; Roelofs, A.P.A.; Levelt, W.J.M.

2004-01-01

Naming digital clocks (e.g., 2:45, say "quarter to three") requires conceptual operations on the minute and hour information displayed in the input for producing the correct relative time expression. The interplay of these conceptual operations was investigated using a repetition priming paradigm.

Cesium 137 in oils and plants from Guatemala

International Nuclear Information System (INIS)

Ayala, R.E.; Perez, J.F.

1993-01-01

Since 1990 the project of radioactive and environmental contamination started in Guatemala. Studies about the radioactive contamination levels are made within the framework of this project. Cesium-137 has been an interest radionuclide, because it is a fission product released to the environment by the use of nuclear weapons and nuclear power plants accidents. The sampling consisted in collection of soil and grass in 20 provinces of Guatemala, one point by province, and it was made in 1990. The cesium-137 concentration in the samples, was determined by gamma spectrometry, using an hyper pure germanium detector. The results show the presence of radioactive contamination in soil and grass due to cesium-137, at levels that might be considered as normal. The levels found are not harmful for human health, and its importance is the fact that can be used as reference levels for the environmental radioactivity monitoring in Guatemala

Cesium uptake capacity of simulated ferrocyanide tank waste. Interim report FY 1994, Ferrocyanide Safety Project

International Nuclear Information System (INIS)

Burgeson, I.E.; Bryan, S.A.; Burger, L.E.

1994-09-01

The objective of this project is to determine the capacity for 137 CS uptake by mixed metal ferrocyanides present in Hanford waste tanks, and to assess the potential for aggregation of these 137 CS exchanged materials to form tank ''hot-spots.'' This research, performed at the Pacific Northwest Laboratory (PNL) for the Westinghouse Hanford Company (WHC), stems from concerns of possible localized radiolytic heating within the tanks. If radioactive cesium is exchanged and concentrated by the remaining nickel ferrocyanide present in the tanks, this heating could cause temperatures to rise above the safety limits specified for the ferrocyanide tanks. For the purposes of this study, two simulants, In-Farm-2 and U-Plant-2, were chosen to represent the wastes generated by the scavenging processes. These simulants were formulated using protocols from the original cesium scavenging campaign. Later additions of cesium-rich wastes from various processes also were considered. The simulants were prepared and centrifuged to obtain a moist ferrocyanide sludge. The centrifuged sludges were treated with the original supernate spiked with a known amount of cesium nitrate. After analysis by flame atomic absorption spectrometry, distribution coefficients (K d ) were calculated. The capacity of solid waste simulants to exchange radioactive cesium from solution was examined. Initial results showed that the greater the molar ratio of cesium to cesium nickel ferrocyanide, the less effective the exchange of cesium from solution. The theoretical capacity of 2 mol cesium per mol of nickel ferrocyanide was not observed. The maximum capacity under experimental conditions was 0.35 mol cesium per mol nickel ferrocyanide. Future work on this project will examine the layering tendency of the cesium nickel ferrocyanide species

Experimental study on cesium immobilization in struvite structures

International Nuclear Information System (INIS)

Wagh, Arun S.; Sayenko, S.Y.; Shkuropatenko, V.A.; Tarasov, R.V.; Dykiy, M.P.; Svitlychniy, Y.O.; Virych, V.D.; Ulybkina, E.A.

2016-01-01

Graphical abstract: X-ray diffraction patterns of Ceramicrete forms, green representing struvite-K, and red, struvite-(K,Cs) with 10 wt.% CsCl in it. Cs substitutes partially for K, which immobilizes Cs at room temperature by the acid–base reaction. - Highlights: • Struvite structure of Ceramicrete is an excellent host of radioactive cesium. • The volatility problem of cesium can be avoided by this method. • This method can be used to produce cesium waste forms in ambient conditions. • It can also be used to pretreat cesium in glass vitrification technology. • It also provides a method to produce safe sealed radioactive sources of cesium. - Abstract: Ceramicrete, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid–base reaction between magnesium oxide and mono potassium phosphate that has a struvite-K mineral structure. In this study, we demonstrate that this crystalline structure is ideal for incorporating radioactive Cs into a Ceramicrete matrix. This is accomplished by partially replacing K by Cs in the struvite-K structure, thus forming struvite-(K, Cs) mineral. X-ray diffraction and thermo-gravimetric analyses are used to confirm such a replacement. The resulting product is non-leachable and stable at high temperatures, and hence it is an ideal matrix for immobilizing Cs found in high-activity nuclear waste streams. The product can also be used for immobilizing secondary waste streams generated during glass vitrification of spent fuel, or the method described in this article can be used as a pretreatment method during glass vitrification of high level radioactive waste streams. Furthermore, it suggests a method of producing safe commercial radioactive Cs sources.

Experimental study on cesium immobilization in struvite structures

Energy Technology Data Exchange (ETDEWEB)

Wagh, Arun S., E-mail: asw@anl.gov [Environmental Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, IL 60439 (United States); Sayenko, S.Y.; Shkuropatenko, V.A.; Tarasov, R.V.; Dykiy, M.P.; Svitlychniy, Y.O.; Virych, V.D.; Ulybkina, E.A. [National Science Center, Kharkov Institute of Physics and Technology, Kharkov (Ukraine)

2016-01-25

Graphical abstract: X-ray diffraction patterns of Ceramicrete forms, green representing struvite-K, and red, struvite-(K,Cs) with 10 wt.% CsCl in it. Cs substitutes partially for K, which immobilizes Cs at room temperature by the acid–base reaction. - Highlights: • Struvite structure of Ceramicrete is an excellent host of radioactive cesium. • The volatility problem of cesium can be avoided by this method. • This method can be used to produce cesium waste forms in ambient conditions. • It can also be used to pretreat cesium in glass vitrification technology. • It also provides a method to produce safe sealed radioactive sources of cesium. - Abstract: Ceramicrete, a chemically bonded phosphate ceramic, was developed for nuclear waste immobilization and nuclear radiation shielding. Ceramicrete products are fabricated by an acid–base reaction between magnesium oxide and mono potassium phosphate that has a struvite-K mineral structure. In this study, we demonstrate that this crystalline structure is ideal for incorporating radioactive Cs into a Ceramicrete matrix. This is accomplished by partially replacing K by Cs in the struvite-K structure, thus forming struvite-(K, Cs) mineral. X-ray diffraction and thermo-gravimetric analyses are used to confirm such a replacement. The resulting product is non-leachable and stable at high temperatures, and hence it is an ideal matrix for immobilizing Cs found in high-activity nuclear waste streams. The product can also be used for immobilizing secondary waste streams generated during glass vitrification of spent fuel, or the method described in this article can be used as a pretreatment method during glass vitrification of high level radioactive waste streams. Furthermore, it suggests a method of producing safe commercial radioactive Cs sources.

Transcripts from the Circadian Clock: Telling Time and Season

NARCIS (Netherlands)

K. Brand (Karl)

2011-01-01

textabstractWe all know it when we wake mere moments before an alarm clock is scheduled to wake us: our body clock made the alarm clock redundant. This phenomenon is driven by an endogenous timer known as the biological, or circadian clock. Each revolution of the Earth about its own axis produces

Biological timing and the clock metaphor: oscillatory and hourglass mechanisms.

Science.gov (United States)

Rensing, L; Meyer-Grahle, U; Ruoff, P

2001-05-01

Living organisms have developed a multitude of timing mechanisms--"biological clocks." Their mechanisms are based on either oscillations (oscillatory clocks) or unidirectional processes (hourglass clocks). Oscillatory clocks comprise circatidal, circalunidian, circadian, circalunar, and circannual oscillations--which keep time with environmental periodicities--as well as ultradian oscillations, ovarian cycles, and oscillations in development and in the brain, which keep time with biological timescales. These clocks mainly determine time points at specific phases of their oscillations. Hourglass clocks are predominantly found in development and aging and also in the brain. They determine time intervals (duration). More complex timing systems combine oscillatory and hourglass mechanisms, such as the case for cell cycle, sleep initiation, or brain clocks, whereas others combine external and internal periodicities (photoperiodism, seasonal reproduction). A definition of a biological clock may be derived from its control of functions external to its own processes and its use in determining temporal order (sequences of events) or durations. Biological and chemical oscillators are characterized by positive and negative feedback (or feedforward) mechanisms. During evolution, living organisms made use of the many existing oscillations for signal transmission, movement, and pump mechanisms, as well as for clocks. Some clocks, such as the circadian clock, that time with environmental periodicities are usually compensated (stabilized) against temperature, whereas other clocks, such as the cell cycle, that keep time with an organismic timescale are not compensated. This difference may be related to the predominance of negative feedback in the first class of clocks and a predominance of positive feedback (autocatalytic amplification) in the second class. The present knowledge of a compensated clock (the circadian oscillator) and an uncompensated clock (the cell cycle), as well

The Square Light Clock and Special Relativity

Science.gov (United States)

Galli, J. Ronald; Amiri, Farhang

2012-01-01

A thought experiment that includes a square light clock is similar to the traditional vertical light beam and mirror clock, except it is made up of four mirrors placed at a 45[degree] angle at each corner of a square of length L[subscript 0], shown in Fig. 1. Here we have shown the events as measured in the rest frame of the square light clock. By…

A precise clock distribution network for MRPC-based experiments

International Nuclear Information System (INIS)

Wang, S.; Cao, P.; Shang, L.; An, Q.

2016-01-01

In high energy physics experiments, the MRPC (Multi-Gap Resistive Plate Chamber) detectors are widely used recently which can provide higher-resolution measurement for particle identification. However, the application of MRPC detectors leads to a series of challenges in electronics design with large number of front-end electronic channels, especially for distributing clock precisely. To deal with these challenges, this paper presents a universal scheme of clock transmission network for MRPC-based experiments with advantages of both precise clock distribution and global command synchronization. For precise clock distributing, the clock network is designed into a tree architecture with two stages: the first one has a point-to-multipoint long range bidirectional distribution with optical channels and the second one has a fan-out structure with copper link inside readout crates. To guarantee the precision of clock frequency or phase, the r-PTP (reduced Precision Time Protocol) and the DDMTD (digital Dual Mixer Time Difference) methods are used for frequency synthesis, phase measurement and adjustment, which is implemented by FPGA (Field Programmable Gate Array) in real-time. In addition, to synchronize global command execution, based upon this clock distribution network, synchronous signals are coded with clock for transmission. With technique of encoding/decoding and clock data recovery, signals such as global triggers or system control commands, can be distributed to all front-end channels synchronously, which greatly simplifies the system design. The experimental results show that both the clock jitter (RMS) and the clock skew can be less than 100 ps.

Theoretical study of the chemical properties of cesium hydride; Teoreticke studium chemickych vlastnosti hydridu cezia

Energy Technology Data Exchange (ETDEWEB)

Skoviera, J [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra fyzikalnej a teoretickej chemie, 84215 Bratislava (Slovakia)

2012-04-25

A theoretical study of radiofrequency source of hydrogen ions in the International Thermonuclear Experimental Reactor (ITER) used a cesium grid as a source of electrons for ionization of hydrogen. In the process of ionization of hydrogen, however, there is a weathering of cesium grid, resulting into a group of undesired products - cesium hydrides and materials derived from cesium hydride. We calculated the potential curves of cesium hydride and of its anion and cation, their spectroscopic properties and partly their electrical properties. To make electrical properties comparable with the experiment, we calculated for all also the vibration corrections. Lack of convergence in RASSCF step caused, that the electrical properties of excited states are still an open question of chemical properties of cesium hydride. (authors)

Relativity theory and time perception: single or multiple clocks?

Science.gov (United States)

Buhusi, Catalin V; Meck, Warren H

2009-07-22

Current theories of interval timing assume that humans and other animals time as if using a single, absolute stopwatch that can be stopped or reset on command. Here we evaluate the alternative view that psychological time is represented by multiple clocks, and that these clocks create separate temporal contexts by which duration is judged in a relative manner. Two predictions of the multiple-clock hypothesis were tested. First, that the multiple clocks can be manipulated (stopped and/or reset) independently. Second, that an event of a given physical duration would be perceived as having different durations in different temporal contexts, i.e., would be judged differently by each clock. Rats were trained to time three durations (e.g., 10, 30, and 90 s). When timing was interrupted by an unexpected gap in the signal, rats reset the clock used to time the "short" duration, stopped the "medium" duration clock, and continued to run the "long" duration clock. When the duration of the gap was manipulated, the rats reset these clocks in a hierarchical order, first the "short", then the "medium", and finally the "long" clock. Quantitative modeling assuming re-allocation of cognitive resources in proportion to the relative duration of the gap to the multiple, simultaneously timed event durations was used to account for the results. These results indicate that the three event durations were effectively timed by separate clocks operated independently, and that the same gap duration was judged relative to these three temporal contexts. Results suggest that the brain processes the duration of an event in a manner similar to Einstein's special relativity theory: A given time interval is registered differently by independent clocks dependent upon the context.

Relativity theory and time perception: single or multiple clocks?

Directory of Open Access Journals (Sweden)

Catalin V Buhusi

2009-07-01

Full Text Available Current theories of interval timing assume that humans and other animals time as if using a single, absolute stopwatch that can be stopped or reset on command. Here we evaluate the alternative view that psychological time is represented by multiple clocks, and that these clocks create separate temporal contexts by which duration is judged in a relative manner. Two predictions of the multiple-clock hypothesis were tested. First, that the multiple clocks can be manipulated (stopped and/or reset independently. Second, that an event of a given physical duration would be perceived as having different durations in different temporal contexts, i.e., would be judged differently by each clock.Rats were trained to time three durations (e.g., 10, 30, and 90 s. When timing was interrupted by an unexpected gap in the signal, rats reset the clock used to time the "short" duration, stopped the "medium" duration clock, and continued to run the "long" duration clock. When the duration of the gap was manipulated, the rats reset these clocks in a hierarchical order, first the "short", then the "medium", and finally the "long" clock. Quantitative modeling assuming re-allocation of cognitive resources in proportion to the relative duration of the gap to the multiple, simultaneously timed event durations was used to account for the results.These results indicate that the three event durations were effectively timed by separate clocks operated independently, and that the same gap duration was judged relative to these three temporal contexts. Results suggest that the brain processes the duration of an event in a manner similar to Einstein's special relativity theory: A given time interval is registered differently by independent clocks dependent upon the context.

A Novel Method of Clock Synchronization in Distributed Systems

Science.gov (United States)

Li, Gun; Niu, Meng-jie; Chai, Yang-shun; Chen, Xin; Ren, Yan-qiu

2017-04-01

Time synchronization plays an important role in the spacecraft formation flight and constellation autonomous navigation, etc. For the application of clock synchronization in a network system, it is not always true that all the observed nodes in the network are interconnected, therefore, it is difficult to achieve the high-precision time synchronization of a network system in the condition that a certain node can only obtain the measurement information of clock from a single neighboring node, but cannot obtain it from other nodes. Aiming at this problem, a novel method of high-precision time synchronization in a network system is proposed. In this paper, each clock is regarded as a node in the network system, and based on the definition of different topological structures of a distributed system, the three control algorithms of time synchronization under the following three cases are designed: without a master clock (reference clock), with a master clock (reference clock), and with a fixed communication delay in the network system. And the validity of the designed clock synchronization protocol is proved by both stability analysis and numerical simulation.

Accumulation of strontium 90 and cesium 137 in some hydrobionts

International Nuclear Information System (INIS)

Boyadzhiev, A.; Keslev, D.; Kerteva, A.; Novakova, E.

1974-01-01

Factors responsible for the accumulation of strontium 90 and cesium 137 in some plant organisms, characteristic for fishes in Bulgarian fresh-water reservoirs and in Black Seawater, were examined. The investigated samples were taken during spring, summer and autumn-winter seasons 1967/1968. Each sample burnt to ashes at 450 0 C was examined for strontium 90 and cesium 137 content as well as stable isotopes of calcuim and potassium. Accumulation factors for strontium 90 and cesium 137 were significantly higher in freshwater hydrobionts than in seawater hydrobionts. This could be explained by variations in the concentration of stable isotopes of calcium and potassium from freshwater reservoirs and from seawater. Potassium and calcium concentrations were relatively constant in seawater while in freshwater they were significantly variable. Accumulation factors for these radionuclides increased according to the amount of rain and the altitude above sea level. Strontium 90 was deposited mostly in fins, less in scales and least in the meat of fishes; cesium 137 was mainly deposited in the meat and less in the other parts of fishes. The highest accumulation factors for strontium 90 were determined in fishes and for cesium 137 in plant organisms. The most convenient plant and fish species for tracing radioactive contamination of freshwater reservoirs and in the Black Sea were indicated. (A.B.)

The molar enthalpies of solution and vapour pressures of saturated aqueous solutions of some cesium salts

International Nuclear Information System (INIS)

Apelblat, Alexander; Korin, Eli

2006-01-01

Vapour pressures of water over saturated solutions of cesium chloride, cesium bromide, cesium nitrate, cesium sulfate, cesium formate, and cesium oxalate were determined as a function of temperature. These vapour pressures were used to evaluate the water activities, osmotic coefficients and molar enthalpies of vapourization. Molar enthalpies of solution of cesium chloride, Δ sol H m (T = 295.73 K; m = 0.0622 mol . kg -1 ) = (17.83 ± 0.50) kJ . mol -1 ; cesium bromide, Δ sol H m (T = 293.99 K; m = 0.0238 mol . kg -1 ) = (26.91 ± 0.59) kJ . mol -1 ; cesium nitrate, Δ sol H m (T = 294.68 K; m = 0.0258 mol . kg -1 ) = (37.1 ± 2.3) kJ . mol -1 ; cesium sulfate, Δ sol H m (T = 296.43 K; m = 0.0284 mol . kg -1 ) (16.94 ± 0.43) kJ . mol -1 ; cesium formate, Δ sol H m (T = 295.64 K; m = 0.0283 mol . kg -1 ) = (11.10 ± 0.26) kJ . mol -1 and Δ sol H m (T = 292.64 K; m = 0.0577 mol . kg -1 ) = (11.56 ± 0.56) kJ . mol -1 ; and cesium oxalate, Δ sol H m (T = 291.34 K; m = 0.0143 mol . kg -1 ) = (22.07 ± 0.16) kJ . mol -1 were determined calorimetrically. The purity of the chemicals was generally greater than 0.99 mass fraction, except for HCOOCs and (COOCs) 2 where purities were approximately 0.95 and 0.97 mass fraction, respectively. The uncertainties are one standard deviations

Physical Layer Ethernet Clock Synchronization

Science.gov (United States)

2010-11-01

42 nd Annual Precise Time and Time Interval (PTTI) Meeting 77 PHYSICAL LAYER ETHERNET CLOCK SYNCHRONIZATION Reinhard Exel, Georg...oeaw.ac.at Nikolaus Kerö Oregano Systems, Mohsgasse 1, 1030 Wien, Austria E-mail: nikolaus.keroe@oregano.at Abstract Clock synchronization ...is a service widely used in distributed networks to coordinate data acquisition and actions. As the requirement to achieve tighter synchronization

Phase separation of cesium from lead borosilicate glass by heat treatment under a reducing atmosphere

Energy Technology Data Exchange (ETDEWEB)

Xu, Zhanglian; Okada, Takashi, E-mail: t-okada@u-fukui.ac.jp; Nishimura, Fumihiro; Yonezawa, Susumu

2016-11-05

Highlights: • Cesium was phase separated from lead borosilicate glass under a reductive atmosphere. • The phase separation occurred on the glass surface that was in contact with the gas. • The leachability of cesium was enhanced by the phase separation. • The degree of such enhancement varied depending on the heat treatment conditions. - Abstract: A phase-separation technique for removing sodium from glass using a heat-treatment method under a reducing atmosphere was previously developed for sodium recovery from waste glass. In this study, this technique was applied to cesium-containing lead borosilicate glass to concentrate the cesium in phase-separated sodium-rich materials for efficient cesium extraction. The theoretical phase-separation temperature of the sodium-rich phase was simulated by thermodynamic equilibrium calculations and was predicted to occur below 700 °C for lead borosilicate glass. Experimentally, a simulated lead borosilicate glass was melted at 1000 °C and subsequently annealed below 700 °C under a CO-containing reducing atmosphere. The phase separation of cesium was found to occur with sodium enrichment on the glass surface that was in contact with the gas phase, promoting cesium extraction from the treated glass using water. The cesium extraction efficiency was affected by the surface area of the treated glass that was in contact with water, and under the examined conditions, the cesium extraction efficiency was up to 66%. Phase separation using reductive heat treatment, combined with a water leaching technique, is suggested to be effective for extracting cesium incorporated in borosilicate glass waste.

Functions and requirements for a cesium demonstration unit

International Nuclear Information System (INIS)

Howden, G.F.

1994-04-01

Westinghouse Hanford Company is investigating alternative means to pretreat the wastes in the Hanford radioactive waste storage tanks. Alternatives include (but are not limited to) in-tank pretreatment, use of above ground transportable compact processing units (CPU) located adjacent to a tank farm, and fixed processing facilities. This document provides the functions and requirements for a CPU to remove cesium from tank waste as a demonstration of the CPU concept. It is therefore identified as the Cesium Demonstration Unit CDU

A clock network for geodesy and fundamental science.

Science.gov (United States)

Lisdat, C; Grosche, G; Quintin, N; Shi, C; Raupach, S M F; Grebing, C; Nicolodi, D; Stefani, F; Al-Masoudi, A; Dörscher, S; Häfner, S; Robyr, J-L; Chiodo, N; Bilicki, S; Bookjans, E; Koczwara, A; Koke, S; Kuhl, A; Wiotte, F; Meynadier, F; Camisard, E; Abgrall, M; Lours, M; Legero, T; Schnatz, H; Sterr, U; Denker, H; Chardonnet, C; Le Coq, Y; Santarelli, G; Amy-Klein, A; Le Targat, R; Lodewyck, J; Lopez, O; Pottie, P-E

2016-08-09

Leveraging the unrivalled performance of optical clocks as key tools for geo-science, for astronomy and for fundamental physics beyond the standard model requires comparing the frequency of distant optical clocks faithfully. Here, we report on the comparison and agreement of two strontium optical clocks at an uncertainty of 5 × 10(-17) via a newly established phase-coherent frequency link connecting Paris and Braunschweig using 1,415 km of telecom fibre. The remote comparison is limited only by the instability and uncertainty of the strontium lattice clocks themselves, with negligible contributions from the optical frequency transfer. A fractional precision of 3 × 10(-17) is reached after only 1,000 s averaging time, which is already 10 times better and more than four orders of magnitude faster than any previous long-distance clock comparison. The capability of performing high resolution international clock comparisons paves the way for a redefinition of the unit of time and an all-optical dissemination of the SI-second.

Measurement of parity violation in the 6S-7S transition of cesium using stimulated emission

International Nuclear Information System (INIS)

Lintz, M.

2005-11-01

This document describes the design and implementation of a pump-probe polarimetry experiment in a cesium vapor, aiming at a 1% precision measurement of atomic parity violation (APV) induced by Z 0 boson exchange. The experimental scheme, relying on induced emission by a probe laser, allows a detection efficiency close to unity, and the left-right asymmetry to be measured is amplified during the propagation of the probe beam in the excited vapour. The interest of the result presented here is to cross-check the unique previous result by an experiment with a completely different design, and hence with completely different systematics, that also allows measurements on long-lived isotopes especially 135 Cs (nuclear spin 7/2 like 133 Cs, half-life 3 million years). We have demonstrated improvements in polarimetry techniques (rejection of instrumental errors, implementation of a polarization magnifier), especially in pulsed polarimetry (doubly-differential, balanced-mode polarization analysis). But most importantly, the expected pump-probe chiral optical gain has been observed in a Cs vapor. The precision on the θ pv measurement has been improved to 2.6%, and the achieved signal/noise ratio allows measurements at the 1% precision level. The achieved precision on lm E 1 pv is 2 x 10 -13 ea 0 , 15 times better than the measurements obtained with the lead and thallium atoms. Our result is in agreement with the more precise Boulder result. The required amount of cesium is small enough to allow a measurement with 135 Cs provided one takes reasonable radioprotection measures. (author)

Programmable Clock Waveform Generation for CCD Readout

Energy Technology Data Exchange (ETDEWEB)

Vicente, J. de; Castilla, J.; Martinez, G.; Marin, J.

2006-07-01

Charge transfer efficiency in CCDs is closely related to the clock waveform. In this paper, an experimental framework to explore different FPGA based clock waveform generator designs is described. Two alternative design approaches for controlling the rise/fall edge times and pulse width of the CCD clock signal have been implemented: level-control and time-control. Both approaches provide similar characteristics regarding the edge linearity and noise. Nevertheless, dissimilarities have been found with respect to the area and frequency range of application. Thus, while the time-control approach consumes less area, the level control approach provides a wider range of clock frequencies since it does not suffer capacitor discharge effect. (Author) 8 refs.

Double-resonance optical-pumping effect and ladder-type electromagnetically induced transparency signal without Doppler background in cesium atomic vapour cell

International Nuclear Information System (INIS)

Yang Bao-Dong; Gao Jing; Liang Qiang-Bing; Wang Jie; Zhang Tian-Cai; Wang Jun-Min

2011-01-01

In a Doppler-broadened ladder-type cesium atomic system (6S 1/2 -6P 3/2 -8S 1/2 ), this paper characterizes electromagnetically induced transparency (EIT) in two different experimental arrangements, and investigates the influence of the double-resonance optical-pumping (DROP) effect on EIT in both arrangements. When the probe laser is weak, DROP is explicitly suppressed. When the probe laser is moderate, population of the intermediate level (6P 3/2 F' = 5) is remarkable, therefore DROP is mixed with EIT. An interesting bimodal spectrum with the broad component due to DROP and the narrow part due to EIT has been clearly observed in cesium 6S 1/2 F = 4−6P 3/2 F' = 5−8S 1/2 F″ = 4 transitions. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Cesium-137 accumulation in higher plants before and after Chernobyl

International Nuclear Information System (INIS)

Sawidis, T.; Drossos, E.; Papastefanou, C.; Heinrick, G.

1990-01-01

Cesium-137 concentrations in plant species of three biotypes of northern Greece, differing in location as well as in vegetation, are reported following the Chernobyl reactor accident. The cesium uptake by plants was due to the foliar deposition rather than the root uptake. The highest level of cesium in plants was found in Ranunculus sardous, a pubescent plant. The 137 Cs concentration was about 22kBq kg -1 d.w. A high level of cesium was also found in Salix alba ( 137 Cs: 19.6 kBq kg -1 d.w.), a deciduous tree showing that hairy leaves or leaves having rough and large surfaces can absorb greater amounts of radioactivity (surface effect). A comparison is also made between the results of measurements of the present study and the results of measurements of some herbarium plants collected one year before the accident as well as the results of measurements of some new plants grown and collected one year after the accident resulting in a natural removal rate of 137 Cs in plants varying from 14 to 130 days

Cesium powder and pellets inner container decontamination method determination

International Nuclear Information System (INIS)

Ferrell, P.C.

1998-01-01

The cesium powder and pellets inner container is to be performance tested per the criteria specified in Section 4.0 of HNF-2399, ''Design, Fabrication, and Assembly Criteria for Cesium Powder and Pellet Inner Container.'' The test criteria specifies that the inner container be water tight during decontamination of the exterior surface. Three prototypes will be immersed into a pool of water to simulate a water decontamination process

New separation techniques of cesium by redox type ion exchange materials

International Nuclear Information System (INIS)

Tanihara, Koichi

1998-01-01

RIECS method, new cesium separation method, was developed in which a porous strong base anionic exchanger with copper ferrocyanide (CuFC) and inhibitor were used. Cesium could be separated from the high concentration nitric solution. By developing new impregnation method, large amount of CuFC was impregnated into the micropolar porous resin and silica gel pores. KFC adhered to outside of pores was recovered. Good complex with CuFC was prepared by use of copper chloride in ethyl alcohol solution. The adsorption ratio of cesium increased radically to 80% level in the very small range of hydrazine concentration 1.7 to 2.4x10 -4 M. The adsorption-desorption ratio of cesium did not decrease by repeating it seven times. The glassificated materials decreased large amount of γ-ray unless increase of volume could be produced by built RIECS method in the high level waste processing system. (S.Y.)

Improvement of cesium retention in uranium dioxide by additional phases; Amelioration de la retention du cesium dans le dioxyde d`uranium au moyen de phases exogenes

Energy Technology Data Exchange (ETDEWEB)

Gamaury Dubois, S

1995-09-19

The objective of this study is to improve the cesium retention in nuclear fuel. A bibliographic survey indicates that cesium is rapidly released from uranium dioxide in an accident condition. At temperatures higher than 1500 deg C or in oxidising conditions, our experiments show the difficulty of maintaining cesium inside simulated fuel. Two ternary systems are potentially interesting for the retention of cesium and to reduce the kinetics of release from the fuel: Cs{sub 2}O-Al{sub 2}O{sub 3}-SiO{sub 2} et Cs{sub 2}O-ZrO{sub 2}-SO{sub 2}. The compounds CsAISi{sub 2}O{sub 6} and Cs{sub 2}ZrSi{sub 6}O{sub 15} were studied from 1200 deg C to 2000 deg C by thermogravimetric analysis. The volumetric diffusion coefficients of cesium in these structures, in solid state as well as in liquid one, were measured. A fuel was sintered with (Al{sub 2}O{sub 3} + SiO{sub 2}) or (ZrO{sub 2} + SiO{sub 2}) and the intergranular phase was characterized. In the presence of (Al{sub 2}O{sub 3} + SiO{sub 2}), the sintering is realized at 1610 deg C in H{sub 2}. It is a liquid phase sintering. On the other end, with (ZrO{sub 2} + SiO{sub 2}), the sintering is a low temperature one in oxidising atmosphere. Finally, cesium containing simulated fuels were produced with these additives. According to the effective diffusion coefficients that were measured, the additives improved the retention of cesium. We have predicted the improvement that could be hoped for in a nuclear reactor, depending on the dispersion of the intergranular additives, the temperature and the degree of oxidation of the UO{sub 2+x}. We wait for a factor of 2 for x=0 and more than 8 for x=0.05, up to 2000 deg C. (author). 148 refs., 122 figs., 34 tabs.

Using Integer Clocks to Verify the Timing-Sync Sensor Network Protocol

Science.gov (United States)

Huang, Xiaowan; Singh, Anu; Smolka, Scott A.

2010-01-01

We use the UPPAAL model checker for Timed Automata to verify the Timing-Sync time-synchronization protocol for sensor networks (TPSN). The TPSN protocol seeks to provide network-wide synchronization of the distributed clocks in a sensor network. Clock-synchronization algorithms for sensor networks such as TPSN must be able to perform arithmetic on clock values to calculate clock drift and network propagation delays. They must be able to read the value of a local clock and assign it to another local clock. Such operations are not directly supported by the theory of Timed Automata. To overcome this formal-modeling obstacle, we augment the UPPAAL specification language with the integer clock derived type. Integer clocks, which are essentially integer variables that are periodically incremented by a global pulse generator, greatly facilitate the encoding of the operations required to synchronize clocks as in the TPSN protocol. With this integer-clock-based model of TPSN in hand, we use UPPAAL to verify that the protocol achieves network-wide time synchronization and is devoid of deadlock. We also use the UPPAAL Tracer tool to illustrate how integer clocks can be used to capture clock drift and resynchronization during protocol execution

Cryptochrome mediates light-dependent magnetosensitivity of Drosophila's circadian clock.

Directory of Open Access Journals (Sweden)

Taishi Yoshii

2009-04-01

Full Text Available Since 1960, magnetic fields have been discussed as Zeitgebers for circadian clocks, but the mechanism by which clocks perceive and process magnetic information has remained unknown. Recently, the radical-pair model involving light-activated photoreceptors as magnetic field sensors has gained considerable support, and the blue-light photoreceptor cryptochrome (CRY has been proposed as a suitable molecule to mediate such magnetosensitivity. Since CRY is expressed in the circadian clock neurons and acts as a critical photoreceptor of Drosophila's clock, we aimed to test the role of CRY in magnetosensitivity of the circadian clock. In response to light, CRY causes slowing of the clock, ultimately leading to arrhythmic behavior. We expected that in the presence of applied magnetic fields, the impact of CRY on clock rhythmicity should be altered. Furthermore, according to the radical-pair hypothesis this response should be dependent on wavelength and on the field strength applied. We tested the effect of applied static magnetic fields on the circadian clock and found that flies exposed to these fields indeed showed enhanced slowing of clock rhythms. This effect was maximal at 300 muT, and reduced at both higher and lower field strengths. Clock response to magnetic fields was present in blue light, but absent under red-light illumination, which does not activate CRY. Furthermore, cry(b and cry(OUT mutants did not show any response, and flies overexpressing CRY in the clock neurons exhibited an enhanced response to the field. We conclude that Drosophila's circadian clock is sensitive to magnetic fields and that this sensitivity depends on light activation of CRY and on the applied field strength, consistent with the radical pair mechanism. CRY is widespread throughout biological systems and has been suggested as receptor for magnetic compass orientation in migratory birds. The present data establish the circadian clock of Drosophila as a model system

Removal of cesium from red deer meat

International Nuclear Information System (INIS)

Jandl, J.; Novosad, J.; Francova, J.; Prochazka, H.

1989-01-01

The effect was studied of marinading on the reduction of cesium radionuclide activity in red deer meat contaminated by ingestion of feed containing 134 Cs+ 137 Cs from radioactive fallout following the Chernobyl accident. Two types of marinade were studied, viz., a vinegar infusion and a vinegar infusion with an addition of vegetables and spices. The meat was chopped to cubes of about 1.5 cm in size and the marinading process took place at temperatures of 5 and 11 degC. The drop of cesium content in the meat was determined by gamma spectrometry at given time intervals. The replacement of the marinade and the duration of the process were found to maximally affect efficiency. If the solution was not replaced, about 80% of cesium radionuclides were removed after seven hours of marinading. With one replacement of the infusion the drop in 134 Cs+ 137 Cs radioactivity amounted to up to 90% after seven hours of marinading. No effects were shown of vegetable additions to the vinegar infusion and of the change in temperature from 5 to 11 degC on the efficiency of the process. (author). 3 tabs., 6 refs

Ion exchange flowsheet for recovery of cesium from purex sludge supernatant at B Plant

International Nuclear Information System (INIS)

Carlstrom, R.F.

1977-01-01

Purex Sludge Supernatant (PSS) contains significant amounts of 137 Cs left after removal of strontium from fission product bearing Purex wastes. To remove cesium from PSS, an Ion Exchange Recovery system has been set up in Cells 17-21 at B Plant. The cesium that is recovered is stored within B Plant for eventual purification through the Cesium Purification process in Cell 38 and eventual encapsulation and storage in a powdered form at the Waste Encapsulation Storage Facility. Cesium depleted waste streams from the Ion Exchange processes are transferred to underground storage

Analysis of cesium extracting solvent using GCMS and HPLC

International Nuclear Information System (INIS)

White, T.L.; Herman, C.C.; Crump, S.L.; Marinik, A.R.; Lambert, D.P.; Eibling, R.E.

2007-01-01

A high-level waste (HLW) remediation process scheduled to begin in 2007 at the Savannah River Site is the Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU). The MCU will use a hydrocarbon solvent (diluent) containing a cesium extractant, a calix[4]arene compound, to extract radioactive cesium from caustic HLW. The resulting decontaminated HLW waste or raffinate will be processed into grout at the Saltstone Production Facility (SPF). The cesium containing CSSX stream will undergo washing with dilute nitric acid followed by stripping of the cesium nitrate into a very dilute nitric acid or the strip effluent stream and the CSSX solvent will be recycled. The Defense Waste Processing Facility (DWPF) will receive the strip effluent stream and immobilize the cesium into borosilicate glass. Excess CSSX solvent carryover from the MCU creates a potential flammability problem during DWPF processing. Bench-scale DWPF process testing was performed with simulated waste to determine the fate of the CSSX solvent components. A simple high performance liquid chromatography (HPLC) method was developed to identify the modifier (which is used to increase Cs extraction and extractant solubility) and extractant within the DWPF process. The diluent and trioctylamine (which is used to suppress impurity effect and ion-pair disassociation) were determined using gas chromatography mass spectroscopy (GCMS). To close the organic balance, two types of sample preparation methods were needed. One involved extracting aqueous samples with methylene chloride or hexane, and the second was capturing the off gas of the DWPF process using carbon tubes and rinsing the tubes with carbon disulfide for analysis. This paper addresses the development of the analytical methods and the bench-scale simulated waste study results. (author)

NPAS2 Compensates for Loss of CLOCK in Peripheral Circadian Oscillators.

Directory of Open Access Journals (Sweden)

Dominic Landgraf

2016-02-01

Full Text Available Heterodimers of CLOCK and BMAL1 are the major transcriptional activators of the mammalian circadian clock. Because the paralog NPAS2 can substitute for CLOCK in the suprachiasmatic nucleus (SCN, the master circadian pacemaker, CLOCK-deficient mice maintain circadian rhythms in behavior and in tissues in vivo. However, when isolated from the SCN, CLOCK-deficient peripheral tissues are reportedly arrhythmic, suggesting a fundamental difference in circadian clock function between SCN and peripheral tissues. Surprisingly, however, using luminometry and single-cell bioluminescence imaging of PER2 expression, we now find that CLOCK-deficient dispersed SCN neurons and peripheral cells exhibit similarly stable, autonomous circadian rhythms in vitro. In CLOCK-deficient fibroblasts, knockdown of Npas2 leads to arrhythmicity, suggesting that NPAS2 can compensate for loss of CLOCK in peripheral cells as well as in SCN. Our data overturn the notion of an SCN-specific role for NPAS2 in the molecular circadian clock, and instead indicate that, at the cellular level, the core loops of SCN neuron and peripheral cell circadian clocks are fundamentally similar.

FUNCTIONAL IMPLICATIONS OF THE CLOCK 3111T/C SINGLE-NUCLEOTIDE POLYMORPHISM

Directory of Open Access Journals (Sweden)

Angela Renee Ozburn

2016-04-01

Full Text Available Circadian rhythm disruptions are prominently associated with Bipolar Disorder (BD. Circadian rhythms are regulated by the molecular clock, a family of proteins that function together in a transcriptional-translational feedback loop. The CLOCK protein is a key transcription factor of this feedback loop, and previous studies have found that manipulations of the Clock gene are sufficient to produce manic-like behavior in mice (Roybal et al., 2007. The Clock 3111T/C single-nucleotide polymorphism (SNP; rs1801260 is a genetic variation of the human Clock gene that is significantly associated with increased frequency of manic episodes in BD patients (Benedetti et al., 2003. The 3111T/C SNP is located in the 3’ untranslated region of the Clock gene. In this study, we sought to examine the functional implications of the human Clock 3111T/C SNP by transfecting a mammalian cell line (mouse embryonic fibroblasts isolated from Clock -/- knockout mice with pcDNA plasmids containing the human Clock gene with either the T or C SNP at position 3111. We then measured circadian gene expression over a 24 hour time period. We found that the Clock3111C SNP resulted in higher mRNA levels than the Clock 3111T SNP. Further, we found that Per2, a transcriptional target of CLOCK, was also more highly expressed with Clock 3111C expression, indicating the 3’UTR SNP affects the expression, function and stability of Clock mRNA.

Fast Clock Recovery for Digital Communications

Science.gov (United States)

Tell, R. G.

1985-01-01

Circuit extracts clock signal from random non-return-to-zero data stream, locking onto clock within one bit period at 1-gigabitper-second data rate. Circuit used for synchronization in opticalfiber communications. Derives speed from very short response time of gallium arsenide metal/semiconductor field-effect transistors (MESFET's).

Biological effects of cesium-137 injected in beagle dogs of different ages

International Nuclear Information System (INIS)

Nikula, K.J.; Muggenburg, B.A.; Griffith, W.C.

1995-01-01

The toxicity of cesium-137 ( 137 Cs) in the Beagle dog was investigated at the Argonne National Laboratory (ANL) as part of a program to evaluate the biological effects of internally deposited radionuclides. The toxicity and health effects of 137 Cs are important to understand because 137 Cs is produced in large amounts in light-water nuclear reactors. Large quantities of cesium radioisotopes have entered the human food chain as a result of atmospheric nuclear weapons test, and additional cesium radioisotopes were released during the Chernobyl accident. Although the final analyses are not complete, three findings are significant: older dogs dies significantly earlier than juvenile and young adult dogs; greater occurrence of sarcomas in the cesium-137 injected dogs; the major nonneoplastic effect in dogs surviving beyond 52 d appears to be testicular atrophy

Rocksalt or cesium chloride: Investigating the relative stability of the cesium halide structures with random phase approximation based methods

Science.gov (United States)

Nepal, Niraj K.; Ruzsinszky, Adrienn; Bates, Jefferson E.

2018-03-01

The ground state structural and energetic properties for rocksalt and cesium chloride phases of the cesium halides were explored using the random phase approximation (RPA) and beyond-RPA methods to benchmark the nonempirical SCAN meta-GGA and its empirical dispersion corrections. The importance of nonadditivity and higher-order multipole moments of dispersion in these systems is discussed. RPA generally predicts the equilibrium volume for these halides within 2.4% of the experimental value, while beyond-RPA methods utilizing the renormalized adiabatic LDA (rALDA) exchange-correlation kernel are typically within 1.8%. The zero-point vibrational energy is small and shows that the stability of these halides is purely due to electronic correlation effects. The rAPBE kernel as a correction to RPA overestimates the equilibrium volume and could not predict the correct phase ordering in the case of cesium chloride, while the rALDA kernel consistently predicted results in agreement with the experiment for all of the halides. However, due to its reasonable accuracy with lower computational cost, SCAN+rVV10 proved to be a good alternative to the RPA-like methods for describing the properties of these ionic solids.

Hybrid micro-particles as a magnetically-guidable decontaminant for cesium-eluted ash slurry

Science.gov (United States)

Namiki, Yoshihisa; Ueyama, Toshihiko; Yoshida, Takayuki; Watanabe, Ryoei; Koido, Shigeo; Namiki, Tamami

2014-09-01

Decontamination of the radioactive cesium that is widely dispersed owing to a nuclear power station accident and concentrated in fly ash requires an effective elimination system. Radioactive fly ash contains large amounts of water-soluble cesium that can cause severe secondary contamination and represents a serious health risk, yet its complete removal is complicated and difficult. Here it is shown that a new fine-powder formulation can be magnetically guided to eliminate cesium after being mixed with the ash slurry. This formulation, termed MagCE, consists of a ferromagnetic porous structure and alkaline- and salt-resistant nickel ferrocyanide. It has potent cesium-adsorption- and magnetic-separation-properties. Because of its resistance against physical and chemical attack such as with ash particles, as well as with the high pH and salt concentration of the ash slurry, MagCE simplifies the decontamination process without the need of the continued presence of the hazardous water-soluble cesium in the treated ash.

Do Caucasian and Asian clocks tick differently?

Directory of Open Access Journals (Sweden)

A.A. Barbosa

Full Text Available The Period 3 and Clock genes are important components of the mammalian molecular circadian system. Studies have shown association between polymorphisms in these clock genes and circadian phenotypes in different populations. Nevertheless, differences in the pattern of allele frequency and genotyping distribution are systematically observed in studies with different ethnic groups. To investigate and compare the pattern of distribution in a sample of Asian and Caucasian populations living in Brazil, we evaluated two well-studied polymorphisms in the clock genes: a variable number of tandem repeats (VNTR in PER3 and a single nucleotide polymorphism (SNP in CLOCK. The aim of this investigation was to search for clues about human evolutionary processes related to circadian rhythms. We selected 109 Asian and 135 Caucasian descendants. The frequencies of the shorter allele (4 repeats in the PER3 gene and the T allele in the CLOCK gene among Asians (0.86 and 0.84, respectively were significantly higher than among Caucasians (0.69 and 0.71, respectively. Our results directly confirmed the different distribution of these polymorphisms between the Asian and Caucasian ethnic groups. Given the genetic differences found between groups, two points became evident: first, ethnic variations may have implications for the interpretation of results in circadian rhythm association studies, and second, the question may be raised about which evolutionary conditions shaped these genetic clock variations.

Transmission delays in hardware clock synchronization

Science.gov (United States)

Shin, Kang G.; Ramanathan, P.

1988-01-01

Various methods, both with software and hardware, have been proposed to synchronize a set of physical clocks in a system. Software methods are very flexible and economical but suffer an excessive time overhead, whereas hardware methods require no time overhead but are unable to handle transmission delays in clock signals. The effects of nonzero transmission delays in synchronization have been studied extensively in the communication area in the absence of malicious or Byzantine faults. The authors show that it is easy to incorporate the ideas from the communication area into the existing hardware clock synchronization algorithms to take into account the presence of both malicious faults and nonzero transmission delays.

Test procedures and instructions for Hanford complexant concentrate supernatant cesium removal using CST

Energy Technology Data Exchange (ETDEWEB)

Hendrickson, D.W.

1997-01-08

This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test, using Hanford Complexant Concentrate supernatant liquor from tank 241-AN-107, in a bench-scale column. The cesium sorbent to be tested is crystalline silicotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-023, Hanford Complexant Concentrate Supernatant Cesium Removal Test Plan.

Comparisons of mental clocks.

Science.gov (United States)

Paivio, A

1978-02-01

Subjects in three experiments were presented with pairs of clock times and were required to choose the one in which the hour and minute hand formed the smaller angle. In Experiments 1 and 2, the times were presented digitally, necessitating a transformation into symbolic representations from which the angular size difference could be inferred. The results revealed orderly symbolic distance effects so that comparison reaction time increased as the angular size difference decreased. Moreover, subjects generally reported using imagery to make the judgment, and subjects scoring high on test of imagery ability were faster than those scoring low on such tests. Experiment 3 added a direct perceptual condition in which subjects compared angles between pairs of hands on two drawn (analog) clocks, as well as a mixed condition involving one digital and one analog clock time. The results showed comparable distance effects for all conditions. In addition, reaction time increased from the perceptual, to the mixed, to the pure-digital condition. These results are consistent with predictions from an image-based dual-coding theory.

Photon interactions in a cesium beam

International Nuclear Information System (INIS)

Nygaard, K.J.; Jones, J.D.; Hebner, R.E. Jr

1974-01-01

Photoionization of excited cesium atoms in the 6 2 P3/2 - state has been studied in a triple crossed-beam experiment. A thermal beam of cesium atoms was intersected by one photon beam of wavelength 8521A that served to excite the atoms and another photon beam with wavelengths below 5060A that served to ionize the excited atoms. The resulting ions were detected with a channel electron multiplier. All background effects were discriminated against by chopping the beam of exciting radiation and by analyzing the net count rate with digital synchronous techniques. The relative cross section for photoionization fo Cs(6 2 P3/2) has been measured from threshold (5060A) to 2500A. The results fall off faster than the theoretical calculations of Weisheit and Norcross

Investigations of the sorption of cesium from acid solutions by various inorganic sorbents

International Nuclear Information System (INIS)

Suess, M.; Pfrepper, G.

1981-01-01

Studies have been made to investigate the suitability of various inorganic sorbents for separating and obtaining cesium from acid solutions. In greater details, the distribution coefficients of cesium from nitric acid and ammonium nitrate solution were determined. To determine the saturation capacities it was necessary to plot the isotherms of adsorption from 0.5 N and 3.1 N nitric acid. Experimental sorption from a model solution, of which the composition was equal to that of the liquid Purex waste, enabled the suitability of the various exchangers for obtaining cesium from fission product solutions to be determined. From the results obtained it is apparent that ammonium phosphomolybdate is best suited for obtaining cesium from acid fission product solutions. (orig.)

Actual situation of concentration and inventory of radioactive cesium in Matsukawaura Lagoon sediment, Fukushima Prefecture

International Nuclear Information System (INIS)

Arita, Koichi; Yabe, Tohru; Hayashi, Seiji

2014-01-01

In order to qualitatively evaluate the current status of inventory of radioactive cesium in Matsukawaura Lagoon, profiles of radioactive cesium concentration in sediment cores and sediment characteristics were measured at 36 points. It was shown that sediment characteristics were different even at high concentration of radioactive cesium to the same extent. As a result, the inventory of radioactive cesium were also different. Even at high concentration of radioactive cesium, inventory in southwestern high mud content rate was less than the western. The total inventory of down to 20 cm of sediment throughout Matsukawaura Lagoon was estimated to be about 220 GBq, that more than 80% distributed to 15 cm shallower than has been revealed. (author)

A novel role for methyl cysteinate, a cysteine derivative, in cesium accumulation in Arabidopsis thaliana

DEFF Research Database (Denmark)

Adams, Eri; Miyazaki, Takae; Hayaishi-Satoh, Aya

2017-01-01

Phytoaccumulation is a technique to extract metals from soil utilising ability of plants. Cesium is a valuable metal while radioactive isotopes of cesium can be hazardous. In order to establish a more efficient phytoaccumulation system, small molecules which promote plants to accumulate cesium we...

Preparation and characterization of cesium-137 aluminosilicate pellets for radioactive source applications

International Nuclear Information System (INIS)

Schultz, F.J.; Tompkins, J.A.; Haff, K.W.; Case, F.N.

1981-07-01

Twenty-seven fully loaded 137 Cs aluminosilicate pellets were fabricated in a hot cell by the vacuum hot pressing of a cesium carbonate/montmorillonite clay mixture at 1500 0 C and 570 psig. Four pellets were selected for characterization studies which included calorimetric measurements, metallography, scanning electron microscope and electron backscattering (SEM-BSE), electron microprobe, x-ray diffraction, and cesium ion leachability measurements. Each test pellet contained 437 to 450 curies of 137 Cs as determined by calorimetric measurements. Metallographic examinations revealed a two-phase system: a primary, granular, gray matrix phase containing large and small pores and small pore agglomerations, and a secondary fused phase interspersed throughout the gray matrix. SEM-BSE analyses showed that cesium and silicon were uniformly distributed throughout both phases of the pellet. This indicated that the cesium-silicon-clay reaction went to completion. Aluminum homogeneity was unconfirmed due to the high background noise associated with the inherent radioactivity of the test specimens. X-ray diffraction analyses of both radioactive and non-radioactive aluminosilicate pellets confirmed the crystal lattice structure to be pollucite. Cesium ion quasistatic leachability measurements determined the leach rates of fully loaded 137 Cs sectioned pollucite pellets to date to be 4.61 to 34.4 x 10 -10 kg m -2 s -1 , while static leach tests performed on unsectioned fully loaded pellets showed the leach rates of the cesium ion to date to be 2.25 to 3.41 x 10 -12 kg m -2 s -1 . The cesium ion diffusion coefficients through the pollucite pellet were calculated using Fick's first and second laws of diffusion. The diffusion coefficients calculated for three tracer level 137 Cs aluminosilicate pellets were 1.29 x 10 -16 m 2 s -1 , 6.88 x 10 -17 m 2 s -1 , and 1.35 x 10 -17 m 2 s -1 , respectively

Evidence for widespread dysregulation of circadian clock progression in human cancer

Directory of Open Access Journals (Sweden)

Jarrod Shilts

2018-01-01

Full Text Available The ubiquitous daily rhythms in mammalian physiology are guided by progression of the circadian clock. In mice, systemic disruption of the clock can promote tumor growth. In vitro, multiple oncogenes can disrupt the clock. However, due to the difficulties of studying circadian rhythms in solid tissues in humans, whether the clock is disrupted within human tumors has remained unknown. We sought to determine the state of the circadian clock in human cancer using publicly available transcriptome data. We developed a method, called the clock correlation distance (CCD, to infer circadian clock progression in a group of samples based on the co-expression of 12 clock genes. Our method can be applied to modestly sized datasets in which samples are not labeled with time of day and coverage of the circadian cycle is incomplete. We used the method to define a signature of clock gene co-expression in healthy mouse organs, then validated the signature in healthy human tissues. By then comparing human tumor and non-tumor samples from twenty datasets of a range of cancer types, we discovered that clock gene co-expression in tumors is consistently perturbed. Subsequent analysis of data from clock gene knockouts in mice suggested that perturbed clock gene co-expression in human cancer is not caused solely by the inactivation of clock genes. Furthermore, focusing on lung cancer, we found that human lung tumors showed systematic changes in expression in a large set of genes previously inferred to be rhythmic in healthy lung. Our findings suggest that clock progression is dysregulated in many solid human cancers and that this dysregulation could have broad effects on circadian physiology within tumors. In addition, our approach opens the door to using publicly available data to infer circadian clock progression in a multitude of human phenotypes.

Efficiency of fly ash belite cement and zeolite matrices for immobilizing cesium

International Nuclear Information System (INIS)

Goni, S.; Guerrero, A.; Lorenzo, M.P.

2006-01-01

The efficiency of innovative matrices for immobilizing cesium is presented in this work. The matrix formulation included the use of fly ash belite cement (FABC-2-W) and gismondine-type Na-P1 zeolite, both of which are synthesized from fly ash of coal combustion. The efficiency for immobilizing cesium is evaluated from the leaching test ANSI/ANS 16.1-1986 at the temperature of 40 deg. C, from which the apparent diffusion coefficient of cesium is obtained. Matrices with 100% of FABC-2-W are used as a reference. The integrity of matrices is evaluated by porosity and pore-size distribution from mercury intrusion porosimetry, X-ray diffraction and nitrogen adsorption analyses. Both matrices can be classified as good solidify systems for cesium, specially the FABC-2-W/zeolite matrix in which the replacement of 50% of belite cement by the gismondine-type Na-P1 zeolite caused a decrease of two orders of magnitude of cesium mean Effective Diffusion Coefficient (D e ) (2.8e-09 cm 2 /s versus 2.2e-07 cm 2 /s, for FABC-2-W/zeolite and FABC-2-W matrices, respectively)

Biological effects of cesium-137 injected in beagle dogs of different ages

Energy Technology Data Exchange (ETDEWEB)

Nikula, K.J.; Muggenburg, B.A.; Griffith, W.C. [and others

1995-12-01

The toxicity of cesium-137 ({sup 137}Cs) in the Beagle dog was investigated at the Argonne National Laboratory (ANL) as part of a program to evaluate the biological effects of internally deposited radionuclides. The toxicity and health effects of {sup 137}Cs are important to understand because {sup 137}Cs is produced in large amounts in light-water nuclear reactors. Large quantities of cesium radioisotopes have entered the human food chain as a result of atmospheric nuclear weapons test, and additional cesium radioisotopes were released during the Chernobyl accident. Although the final analyses are not complete, three findings are significant: older dogs dies significantly earlier than juvenile and young adult dogs; greater occurrence of sarcomas in the cesium-137 injected dogs; the major nonneoplastic effect in dogs surviving beyond 52 d appears to be testicular atrophy.

Vane clocking effects in an embedded compressor stage

Science.gov (United States)

Key, Nicole Leanne

The objective of this research was to experimentally investigate the effects of vane clocking, the circumferential indexing of adjacent vane rows with similar vane counts, in an embedded compressor stage. Experiments were performed in the Purdue 3-Stage Compressor, which consists of an IGV followed by three stages. The IGV, Stator 1, and Stator 2 have identical vane counts of 44, and the effects of clocking were studied on Stage 2. The clocking configuration that located the upstream vane wake on the Stator 2 leading edge was identified with total pressure measurements at the inlet to Stator 2 and confirmed with measurements at the exit of Stator 2. For both loading conditions, the total temperature results showed that there was no measurable change associated with vane clocking in the amount of work done on the flow. At design loading, the change in stage efficiency with vane clocking was 0.27 points between the maximum and minimum efficiency clocking configurations. The maximum efficiency configuration was the case where the Stator 1 wake impinged on the Stator 2 leading edge. This condition produced a shallower and thinner Stator 2 wake compared to the clocking configuration that located the wake in the middle of the Stator 2 passage. By locating the Stator 1 wake at the leading edge, it dampened the Stator 2 boundary layer response to inlet fluctuations associated with the Rotor 2 wakes. At high loading, the change in Stage 2 efficiency increased to 1.07 points; however, the maximum efficiency clocking configuration was the case where the Stator 1 wake passed through the middle of the downstream vane passage. At high loading, the flow physics associated with vane clocking were different than at design loading because the location of the Stator 1 wake fluid on the Stator 2 leading edge triggered a boundary layer separation on the suction side of Stator 2 producing a wider and deeper wake. Vane clocking essentially affects the amount of interaction between the

Math Clock: Perangkat Penunjuk Waktu Kreatif untuk Olahraga Otak

Directory of Open Access Journals (Sweden)

Galuh Boy Hertantyo

2014-11-01

Full Text Available Brain is one of the most vital parts for humans, with the number of brain function that is needed for the body, the brain becomes a very important part of the human body. If there is damage to the brain will certainly cause the performance of the human body will not run properly. Because of that, it’s very important to maintain brain health. There is a way to maintain brain health, for example is by doing brain exercise. Examples of brain exercise is to do simple math calculations or doing brain games like sudoku. Because of that, created a tool that can help the brain to maintain brain exercise. The tool is called math clock. Making math clock tool consists of hardware and software. The hardware consists of RTC as real time data input, ATmega328 as microcontroller and dot matrix 32x16 as a tool to display the output that has been processed by the microcontroller. The software is built using C with Arduino IDE. Math clock will process the data from RTC then processed it, in microcontroller so when output displayed on dot matrix, output will be simple mathematical operation with real time clock data on it. Test results show that, math clock is capable of displaying a simple mathematical calculation operations such as addition, subtraction, multiplication and division. The mathematical operation that display on math clock, appears to be random, so it’s not triggered by same mathematical operation. In math clock the display will change every 20 second, so in 1 minute there are 3 different kinds of mathematical operations. The results of questionnaires of 10 different students, showed 9 out of 10 students said math clock is a tool that easy to use as a clock. Math clock will be alternative for doing brain exercise every day.

The determination of cesium and rubidium in highly radioactive waste liquid

International Nuclear Information System (INIS)

Wei Songsheng

1991-01-01

Cesium and rubidium in high-level waste liquid were determined by atomic absorption spectrometry with the instrument modified for analyzing radioactive samples. The results show that the method is effective and safe. The error of the method is less than +- 3%, and it has been used in the production of cesium

Electromagnetic synchronisation of clocks with finite separation in a rotating system

International Nuclear Information System (INIS)

Cohen, J.M.; Moses, H.E.; Rosenblum, A.; Temple Univ., Philadelphia, PA

1984-01-01

For clocks on the vertices of a triangle, it is shown that clock synchronisation using electromagnetic signals between finitely spaced clocks in a rotating frame leads to the same synchronisation error as a closely spaced band of clocks along the same light path. In addition, the above result is generalised to n equally spaced clocks. (author)

Synthesizing genetic sequential logic circuit with clock pulse generator.

Science.gov (United States)

Chuang, Chia-Hua; Lin, Chun-Liang

2014-05-28

Rhythmic clock widely occurs in biological systems which controls several aspects of cell physiology. For the different cell types, it is supplied with various rhythmic frequencies. How to synthesize a specific clock signal is a preliminary but a necessary step to further development of a biological computer in the future. This paper presents a genetic sequential logic circuit with a clock pulse generator based on a synthesized genetic oscillator, which generates a consecutive clock signal whose frequency is an inverse integer multiple to that of the genetic oscillator. An analogous electronic waveform-shaping circuit is constructed by a series of genetic buffers to shape logic high/low levels of an oscillation input in a basic sinusoidal cycle and generate a pulse-width-modulated (PWM) output with various duty cycles. By controlling the threshold level of the genetic buffer, a genetic clock pulse signal with its frequency consistent to the genetic oscillator is synthesized. A synchronous genetic counter circuit based on the topology of the digital sequential logic circuit is triggered by the clock pulse to synthesize the clock signal with an inverse multiple frequency to the genetic oscillator. The function acts like a frequency divider in electronic circuits which plays a key role in the sequential logic circuit with specific operational frequency. A cascaded genetic logic circuit generating clock pulse signals is proposed. Based on analogous implement of digital sequential logic circuits, genetic sequential logic circuits can be constructed by the proposed approach to generate various clock signals from an oscillation signal.

Lanthanide doped strontium-barium cesium halide scintillators

Science.gov (United States)

Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

2015-06-09

The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

Lattice-induced nonadiabatic frequency shifts in optical lattice clocks

International Nuclear Information System (INIS)

Beloy, K.

2010-01-01

We consider the frequency shift in optical lattice clocks which arises from the coupling of the electronic motion to the atomic motion within the lattice. For the simplest of three-dimensional lattice geometries this coupling is shown to affect only clocks based on blue-detuned lattices. We have estimated the size of this shift for the prospective strontium lattice clock operating at the 390-nm blue-detuned magic wavelength. The resulting fractional frequency shift is found to be on the order of 10 -18 and is largely overshadowed by the electric quadrupole shift. For lattice clocks based on more complex geometries or other atomic systems, this shift could potentially be a limiting factor in clock accuracy.

Improvement of an Atomic Clock using Squeezed Vacuum

DEFF Research Database (Denmark)

Kruse, I.; Lange, K; Peise, Jan

2016-01-01

, the vacuum noise restricts the precision of the interferometer to the standard quantum limit (SQL). Here, we propose and experimentally demonstrate a novel clock configuration that surpasses the SQL by squeezing the vacuum in the empty input state. We create a squeezed vacuum state containing an average of 0.......75 atoms to improve the clock sensitivity of 10000 atoms by 2.05+0.34−0.37  dB. The SQL poses a significant limitation for today’s microwave fountain clocks, which serve as the main time reference. We evaluate the major technical limitations and challenges for devising a next generation of fountain clocks...

Mineral-deposit model for lithium-cesium-tantalum pegmatites

Science.gov (United States)

Bradley, Dwight C.; McCauley, Andrew D.; Stillings, Lisa L.

2017-06-20

Lithium-cesium-tantalum (LCT) pegmatites comprise a compositionally defined subset of granitic pegmatites. The major minerals are quartz, potassium feldspar, albite, and muscovite; typical accessory minerals include biotite, garnet, tourmaline, and apatite. The principal lithium ore minerals are spodumene, petalite, and lepidolite; cesium mostly comes from pollucite; and tantalum mostly comes from columbite-tantalite. Tin ore as cassiterite and beryllium ore as beryl also occur in LCT pegmatites, as do a number of gemstones and high-value museum specimens of rare minerals. Individual crystals in LCT pegmatites can be enormous: the largest spodumene was 14 meters long, the largest beryl was 18 meters long, and the largest potassium feldspar was 49 meters long.Lithium-cesium-tantalum pegmatites account for about one-fourth of the world’s lithium production, most of the tantalum production, and all of the cesium production. Giant deposits include Tanco in Canada, Greenbushes in Australia, and Bikita in Zimbabwe. The largest lithium pegmatite in the United States, at King’s Mountain, North Carolina, is no longer being mined although large reserves of lithium remain. Depending on size and attitude of the pegmatite, a variety of mining techniques are used, including artisanal surface mining, open-pit surface mining, small underground workings, and large underground operations using room-and-pillar design. In favorable circumstances, what would otherwise be gangue minerals (quartz, potassium feldspar, albite, and muscovite) can be mined along with lithium and (or) tantalum as coproducts.Most LCT pegmatites are hosted in metamorphosed supracrustal rocks in the upper greenschist to lower amphibolite facies. Lithium-cesium-tantalum pegmatite intrusions generally are emplaced late during orogeny, with emplacement being controlled by pre-existing structures. Typically, they crop out near evolved, peraluminous granites and leucogranites from which they are inferred to be

The mammalian retina as a clock

Science.gov (United States)

Tosini, Gianluca; Fukuhara, Chiaki

2002-01-01

Many physiological, cellular, and biochemical parameters in the retina of vertebrates show daily rhythms that, in many cases, also persist under constant conditions. This demonstrates that they are driven by a circadian pacemaker. The presence of an autonomous circadian clock in the retina of vertebrates was first demonstrated in Xenopus laevis and then, several years later, in mammals. In X. laevis and in chicken, the retinal circadian pacemaker has been localized in the photoreceptor layer, whereas in mammals, such information is not yet available. Recent advances in molecular techniques have led to the identification of a group of genes that are believed to constitute the molecular core of the circadian clock. These genes are expressed in the retina, although with a slightly different 24-h profile from that observed in the central circadian pacemaker. This result suggests that some difference (at the molecular level) may exist between the retinal clock and the clock located in the suprachiasmatic nuclei of hypothalamus. The present review will focus on the current knowledge of the retinal rhythmicity and the mechanisms responsible for its control.

Cesium-137 in Norwegian milk 1960-1976

International Nuclear Information System (INIS)

Hvinden, T.

1977-03-01

Cesium-137 in milk has been measured at 11 sampling sites in Norway since 1960. The results show seasonal variations, normally with a peak during summer, and variations from district to district, depending upon farming and precipitation conditions. The concentration of cesium-137, averaged over the 11 sampling sites, reached a maximum of 0.44 nanocurie/litre in 1964, decreasing to 0.05 in 1975 and 1976. The range of variations within the 11 sites is of the order of 10. At other sites, with high precipitation and low grazing field qualities, the concentration has been found to be higher than at the 11 sites, giving a range of variations of more than 100. (Auth.)

Cesium titanium silicate and method of making

Science.gov (United States)

Balmer, Mari L.

1997-01-01

The invention is the new material, a ternary compound of cesium, silica, and titania, together with a method of making the ternary compound, cesium titanium silicate pollucite. More specifically, the invention is Cs.sub.2 Ti.sub.2 Si.sub.4 O.sub.13 pollucite which is a new crystalline phase representing a novel class of Ti-containing zeolites. Compositions contain relatively high Cs.sub.2 O and TiO.sub.2 loadings and are durable glass and ceramic materials. The amount of TiO.sub.2 and Cs.sub.2 that can be incorporated into these glasses and crystalline ceramics far exceeds the limits set for the borosilicate high level waste glass.

Modelling the transport of radioactive cesium released from the Fukushima Dai-ichi NPP with sediments through the hydrologic system

Science.gov (United States)

Kinouchi, T.; Omata, T.; Wei, L.; Liu, T.; Araya, M.

2013-12-01

Due to the accident of the Fukushima Dai-ichi Nuclear Power Plant on March 2011, a huge amount of radionuclides including Cesium-134 and Cesium-137 was deposited over the main island of Japan and the Pacific Ocean, resulting in further transfer and diffusion of Cesium through the atmospheric flow, watershed hydrological processes, and terrestrial ecosystem. Particularly, for the transfer of Cesium-134 and Cesium-137, sediments eroded and transported by the rainfall-runoff processes play an important role as Cesium tends to be strongly adsorbed to soil particles such as clay and silt. In this study, we focus on the transport of sediment and adsorbed Cesium in the watershed-scale hydrologic system to predict the long-term change of distribution of Cesium and its discharge to rivers and ocean. We coupled a physically-based distributed hydrological model with the modules of erosion and transport of sediments and adsorbed Cesium, and applied the coupled model to the Abukuma River watershed, which is located over the area of higher deposition of Cesium. In the model, complex land use and land cover distributions, and the effect of human activities such as irrigation, dam control and urban drainage system are taken into accounts. Simulation was conducted for the period of March 2011 until August 2012, with initial spatial distribution of Cesium-134 and Cesium-137 obtained by the airborne survey. Simulated flow rates and sediment concentrations agreed well with observed, and found that since the accident, two major storms in July and September 2011 transported about 50% of total sediments transported during the simulated periods. Cesium concentration in the sediment was reproduced well except for the difference in the initial periods. This difference is attributable to the uncertainty arisen from the initial distribution of Cesium in the soil and the transfer of Cesium from the forest canopy.

Formation, decomposition and cesium adsorption mechanisms of highly alkali-tolerant nickel ferrocyanide prepared by interfacial synthesis

International Nuclear Information System (INIS)

Ichikawa, Tsuneki; Yamada, Kazuo; Osako, Masahiro; Haga, Kazuko

2017-01-01

Highly alkali-tolerant nickel ferrocyanide was prepared as an adsorbent for preventing the leaching of radioactive cesium from municipal solid waste incinerator fly ash containing large amounts of calcium hydroxide and potassium chloride, which act as an alkaline source and the suppressor for cesium adsorption, respectively. Nickel ferrocyanide prepared by contacting concentrated nickel and ferrocyanide solutions without mixing adsorbed cesium ions in alkaline conditions even the concentration of coexisting potassium ions was more than ten thousand times higher than that of the cesium ions. Large particles of nickel ferrocyanide slowly grew at the interface between the two solutions, which reduced the surface energy of the particles and therefore increased the alkali tolerance. The interfacially-synthesized nickel ferrocyanide was possible to prevent the leaching of radioactive cesium from cement-solidified fly ash for a long period. The mechanisms of the formation, selective cesium adsorption, and alkali-induced decomposition of the nickel ferrocyanide were elucidated. Comparison of the cesium adsorption mechanism with that of the other adsorbents revealed that an adsorbent can selectively adsorb cesium ions without much interference from potassium ions, if the following conditions are fulfilled. 1) The adsorption site is small enough for supplying sufficient electrostatic energy for the dehydration of ions adsorbed. 2) Both the cesium and potassium ions are adsorbed as dehydrated ions. 3) The adsorption site is flexible enough for permitting the penetration of dehydrated ions with the size comparable to that of the site. (author)

Effect of electrolytes concentration on recovery of cesium from AMP-PAN by Electrodialysis-Ion Exchange (EDIX)

International Nuclear Information System (INIS)

Mahendra, Ch.; Rajan, K.K.; SatyaSai, P.M.; Anand Babu, C.

2014-01-01

Cesium from the simulated acidic waste solution was separated using Ammonium Molybdophosphate (AMP) - Polyacrylonitrile (PAN) ion exchange resin in column operations. Electrodialysis - Ion exchange (EDIX) has been tried for the recovery of cesium from the AMP-PAN which was saturated with cesium. The electrodialysis setup consists of three compartments; cesium loaded AMP-PAN is placed in the middle compartment and is separated from the anode and cathode compartments by cation exchange membranes. Ammonium sulphate was used as anolyte and HNO 3 as catholyte. 0.1N HNO 3 was circulated in the middle compartment containing AMP-PAN to keep the resin in acidic form. On application of potential, the ammonium ions from the anode compartment migrate towards cathode through the middle compartment where they exchange with cesium ions on the resin and the exchanged cesium ions migrate towards cathode to get concentrated. Some part of cesium is recovered in the middle compartment due to convection. Cesium recovery from the AMP-PAN in the electrodialysis setup was studied at different anolyte and catholyte concentrations. All the experiments were carried out at constant current density of 40 mA/cm 2 for 15h. It was found that more than 50% of cesium recovery was observed for all the experiments studied and recovery percentage increased with increasing the anolyte concentration. It was observed that the electrolytes concentration affects the voltage drop across the cell

High-precision multi-node clock network distribution.

Science.gov (United States)

Chen, Xing; Cui, Yifan; Lu, Xing; Ci, Cheng; Zhang, Xuesong; Liu, Bo; Wu, Hong; Tang, Tingsong; Shi, Kebin; Zhang, Zhigang

2017-10-01

A high precision multi-node clock network for multiple users was built following the precise frequency transmission and time synchronization of 120 km fiber. The network topology adopts a simple star-shaped network structure. The clock signal of a hydrogen maser (synchronized with UTC) was recovered from a 120 km telecommunication fiber link and then was distributed to 4 sub-stations. The fractional frequency instability of all substations is in the level of 10 -15 in a second and the clock offset instability is in sub-ps in root-mean-square average.

Cesium absorption from acidic solutions using ammonium molybdophosphate on a polyacrylonitrile support (AMP-PAN)

International Nuclear Information System (INIS)

Miller, C.J.; Olson, A.L.; Johnson, C.K.

1995-01-01

Recent efforts at the Idaho Chemical Processing Plant (ICPP) have included evaluation of cesium removal technologies as applied to ICPP acidic radioactive waste streams. Ammonium molybdophosphate (AMP) immobilized on a polyacrylonitrile support (AMP-PAN) has been studied as an ion exchange agent for cesium removal from acidic waste solutions. Capacities, distribution coefficients, elutability, and kinetics of cesium-extraction have been evaluated. Exchange breakthrough curves using small columns have been determined from 1M HNO 3 and simulated waste solutions. The theoretical capacity of AMP is 213 g Cs/kg AMP. The average experimental capacity in batch contacts with various acidic solutions was 150 g Cs/kg AMP. The measured cesium distribution coefficients from actual waste solutions were 3287 mL/g for dissolved zirconia calcines, and 2679 mL/g for sodium-bearing waste. The cesium in the dissolved alumina calcines was analyzed for; however, the concentration was below analytical detectable limits resulting in inconclusive results. The reaction kinetics are very rapid (2-10 minutes). Cesium absorption appears to be independent of acid concentration over the range tested (0.1 M to 5 M HNO 3 )

A new ion selective electrode for cesium (I) based on calix[4]arene-crown-6 compounds.

Science.gov (United States)

Ramanjaneyulu, P S; Kumar, Abha Naveen; Sayi, Y S; Ramakumar, K L; Nayak, S K; Chattopadhyay, S

2012-02-29

A polyvinylchloride (PVC) based liquid membrane ion selective electrode (ISE) for cesium has been developed. 25,27-Dihydroxycalix[4]arene-crown-6 (L1), 5,11,17,23-tetra-tert-butyl-25,27-dimethoxycalix[4]arene-crown-6 (L2) and 25,27-bis(1-octyloxy)calix[4]arene-crown-6 (L3) were investigated for their use as ionophores. The cation exchange resin DOWEX-50W was used to maintain low activity Cs+ in inner filling solution to improve the performance. The best response for cesium was observed with L3 along with optimized membrane constituents and composition. Excellent Nernstian response (56.6 mV/decade of Cs(I)) over the concentration range 10(-7) to 10(-2)M of Cs(I) was obtained with a fast response time of less than 10s. Detection limit for Cs(I) using the present ISE is 8.48×10(-8) M Cs(I). Separate solution method (SSM) was applied to ascertain the selectivity for Cs(I) over alkali, alkaline earth and transition metal ions. The response of ISE for Cs(I) was fairly constant over the pH range of 4-11. The lifetime of the electrode is 10 months which is the highest life for any membrane based Cs-ISE so far developed. The concentration of cesium ion in two simulated high level active waste streams was determined and results agreed well with those obtained independently employing AAS. Copyright © 2011 Elsevier B.V. All rights reserved.

Laboratory plant for the separation of cesium from waste solutions of the PUREX process

International Nuclear Information System (INIS)

Richter, M.; Eckert, B.; Riemenschneider, J.; Mallon, C.; Mann, D.

1983-01-01

A laboratory plant for the separation of cesium from a fission product waste solution of the fuel reprocessing is described. The plant consists of two stages. In the first stage cesium is adsorbed on ammonium molybdatophosphate (AMP). Then the adsorbent is dissolved. From the solution cesium is adsorbed on a cationic ion exchanger in the second stage. Then AMP can be reproduced from this solution. For the elution of cesium in the second stage a NH 4 NO 3 solution (3 m) is used. Flow sheet, construction and the control device of the plant are described and the results of tests with a model solution are given. (author)

A high-precision synchronization circuit for clock distribution

International Nuclear Information System (INIS)

Lu Chong; Tan Hongzhou; Duan Zhikui; Ding Yi

2015-01-01

In this paper, a novel structure of a high-precision synchronization circuit, HPSC, using interleaved delay units and a dynamic compensation circuit is proposed. HPSCs are designed for synchronization of clock distribution networks in large-scale integrated circuits, where high-quality clocks are required. The application of a hybrid structure of a coarse delay line and dynamic compensation circuit performs roughly the alignment of the clock signal in two clock cycles, and finishes the fine tuning in the next three clock cycles with the phase error suppressed under 3.8 ps. The proposed circuit is implemented and fabricated using a SMIC 0.13 μm 1P6M process with a supply voltage at 1.2 V. The allowed operation frequency ranges from 200 to 800 MHz, and the duty cycle ranges between [20%, 80%]. The active area of the core circuits is 245 × 134 μm 2 , and the power consumption is 1.64 mW at 500 MHz. (paper)

Mobility of radioactive cesium in soil originated from the Fukushima Daiichi nuclear disaster. Application of extraction experiments

International Nuclear Information System (INIS)

Yoshikazu Kikawada; Takao Oi; Katsumi Hirose; Masaaki Hirose; Atsushi Tsukamoto; Ko Nakamachi; Teruyuki Honda; Hiroaki Takahashi

2015-01-01

Extraction experiments on soil radioactively contaminated by the Fukushima Daiichi Nuclear Power Plant accident were conducted by using a variety of extractants to acquire knowledge on the mobility of radioactive cesium in soil. The experimental results revealed that cesium is tightly bound with soil particles and that radioactive cesium newly deposited on soil due to the accident had apparently a higher mobility than stable cesium commonly existing in soil. The results suggested that radioactive cesium deposited on soil hardly migrates via aqueous processes, although chemical and mineralogical conditions of soil affect their mobility. (author)

Efficient non-linear two-photon effects from the Cesium 6D manifold

Science.gov (United States)

Haluska, Nathan D.; Perram, Glen P.; Rice, Christopher A.

2018-02-01

We report several non-linear process that occur when two-photon pumping the cesium 6D states. Cesium vapor possess some of the largest two-photon pump cross sections in nature. Pumping these cross sections leads to strong amplified spontaneous emission that we observe on over 17 lasing lines. These new fields are strong enough to couple with the pump to create additional tunable lines. We use a heat pipe with cesium densities of 1014 to 1016 cm-3 and 0 to 5 Torr of helium buffer gas. The cesium 6D States are interrogated by both high energy pulses and low power CW sources. We observe four-wave mixing, six-wave mixing, potential two-photon lasing, other unknown nonlinear processes, and the persistence of some processes at low thresholds. This system is also uniquely qualified to support two-photon lasing under the proper conditions.

[Elevated expression of CLOCK is associated with poor prognosis in hepatocellular carcinoma].

Science.gov (United States)

Li, Bo; Yang, Xiliang; Li, Jiaqi; Yang, Yi; Yan, Zhaoyong; Zhang, Hongxin; Mu, Jiao

2018-02-01

Objective To evaluate the expression of circadian locomotor output cycles kaput (CLOCK) and its effects on cell growth in hepatocellular carcinoma (HCC). Methods The expression of CLOCK in 158 pairs of human HCC tissues and matched noncancerous samples was detected by immunohistochemical (IHC) staining. The expression of CLOCK in HCC patients was also verified using the data from GEO and TCGA (a total of 356 cases). The relationship between CLOCK expression and clinicopathological features of HCC patients was analyzed by single factor statistical analysis. Kaplan-Meier survival curves of HCC patients were drawn to study the relationship between the expression level of CLOCK and the survival state. The effect of CLOCK on the growth of HepG2 cells was detected by MTS assay. Results The expression of CLOCK in HCC tissues was significantly higher than that in the adjacent tissues, and the up-regulation of CLOCK expression in HCC tissue was also confirmed in the public data of HCC (356 cases). HCC patients were divided into low CLOCK expression group and high CLOCK expression group. Univariate analysis showed that the expression of CLOCK was related to tumor size, TNM stage, and portal vein invasion in HCC patients. HCC patients with low CLOCK expression had longer overall survival time and relapse-free survival time than those with high CLOCK expression. The proliferation of cells significantly decreased after the expression of CLOCK was knocked down in HepG2 cells. Conclusion The expression of CLOCK in HCC tissues was much higher than that in normal liver tissues, and the high expression of CLOCK indicated the poor prognosis. The knockdown of CLOCK in HCC cells could inhibit the proliferation of HepG2 cells.

Review and assessment of technologies for the separation of cesium from acidic media

Energy Technology Data Exchange (ETDEWEB)

Orth, R.J.; Brooks, K.P.; Kurath, D.E.

1994-09-01

A preliminary literature survey has been conducted to identify and evaluate methods for the separation of cesium from acidic waste. The most promising solvent extraction, precipitation, and ion exchange methods, along with some of the attributes for each method, are listed. The main criteria used in evaluating the separation methods were as follows: (1) good potential for cesium separation must be demonstrated (i.e., cesium decontamination factors on the order of 50 to 100). (2) Good selectivity for cesium over bulk components must be demonstrated. (3) The method must show promise for evolving into a practical and fairly simple process. (4) The process should be safe to operate. (5) The method must be robust (i.e., capable of separating cesium from various acidic waste types). (6) Secondary waste generation must be minimized. (7) The method must show resistance to radiation damage. The most promising separation methods did not necessarily satisfy all of the above criteria, thus key areas requiring further development are suggested for each method. The report discusses in detail these and other areas requiring further development, as well as alternative solvent extraction, precipitation, ion exchange, and {open_quote}other{close_quote} technologies that, based on current information, show less promise for the separation of cesium from acidic wastes because of significant process limitations. When appropriate, the report recommends areas of future development.

Immobilization of aqueous radioactive cesium wastes by conversion to aluminosilicate minerals

International Nuclear Information System (INIS)

Barney, G.S.

1975-05-01

Radioactive cesium (primarily 137 Cs) is a major toxic constituent of liquid wastes from nuclear fuel processing plants. Because of the long half-life, highly penetrating radiation, and mobility of 137 Cs, it is necessary to convert wastes containing this radioisotope into a solid form which will prevent movement to the biosphere during long-term storage. A method for converting cesium wastes to solid, highly insoluble, thermally stable aluminosilicate minerals is described. Aluminum silicate clays (bentonite, kaolin, or pyrophyllite) or hydrous aluminosilicate gels are reacted with basic waste solutions to form pollucite, cesium zeolite (Cs-D), Cs-F, cancrinite, or nepheline. Cesium is trapped in the aluminosilicate crystal lattice of the mineral and is permanently immobilized. The identity of the mineral product is dependent on the waste composition and the SiO 2 /Al 2 O 3 ratio of the clay or gel. The stoichiometry and kinetics of mineral formation reactions are described. The products are evaluated with respect to leachability, thermal stability, and crystal morphology. (U.S.)

Radioactive cesium content in selected food products. Pt. 2. Radioactive cesium in daily food rations of selected population groups

International Nuclear Information System (INIS)

Skibniewska, K.; Smoczynski, S.S.; Wisniewska, I.

1993-01-01

The content of radioactive cesium isotopes emitting beta radiation was studied in daily food rations analysed in diets of working-class and non-working-class families from food products from the regions of Olsztyn, Poznan, Lublin, Warsaw and Wroclaw in 1987 and 1988. In 1987 the highest level of radioactive cesium was found in the food rations in Olsztyn, and lowest in the rations in Poznan (3.32 and 0.65 Bq/kg respectively). In 1988 higher radiocesium content was found in rations composed according to the data on the diet consumed daily in non-working-class families. In that case the highest content was in the daily food rations composed in Warsaw - 2.35 Bq/kg and lowest in Poznan - 1.19 Bq/kg in the daily food rations of working-class families about one half of that value was found. The calculated means values of both analysed rations were: 1.35 for Olsztyn, 0.89 for Poznan, and 1.86 Bq/kg for Warsaw. The calculated mean value of the contamination with radioactive cesium was in 1988 0.93 Bq/kg for the rations in working-class families (in 1987 it was 1.80 Bq/kg). (author). 15 refs, 1 tab

A clock synchronization skeleton based on RTAI

NARCIS (Netherlands)

Huang, Y.; Visser, P.M.; Broenink, Johannes F.

2006-01-01

This paper presents a clock synchronization skeleton based on RTAI (Real Time Application Interface). The skeleton is a thin layer that provides unified but extendible interfaces to the underlying operating system, the synchronization algorithms and the upper level applications in need of clock

Shining a light on the Arabidopsis circadian clock.

Science.gov (United States)

Oakenfull, Rachael J; Davis, Seth J

2017-11-01

The circadian clock provides essential timing information to ensure optimal growth to prevailing external environmental conditions. A major time-setting mechanism (zeitgeber) in clock synchronization is light. Differing light wavelengths, intensities, and photoperiodic duration are processed for the clock-setting mechanism. Many studies on light-input pathways to the clock have focused on Arabidopsis thaliana. Photoreceptors are specific chromic proteins that detect light signals and transmit this information to the central circadian oscillator through a number of different signalling mechanisms. The most well-characterized clock-mediating photoreceptors are cryptochromes and phytochromes, detecting blue, red, and far-red wavelengths of light. Ultraviolet and shaded light are also processed signals to the oscillator. Notably, the clock reciprocally generates rhythms of photoreceptor action leading to so-called gating of light responses. Intermediate proteins, such as Phytochrome interacting factors (PIFs), constitutive photomorphogenic 1 (COP1) and EARLY FLOWERING 3 (ELF3), have been established in signalling pathways downstream of photoreceptor activation. However, the precise details for these signalling mechanisms are not fully established. This review highlights both historical and recent efforts made to understand overall light input to the oscillator, first looking at how each wavelength of light is detected, this is then related to known input mechanisms and their interactions. © 2017 John Wiley & Sons Ltd.

Time without clocks - an attempt

International Nuclear Information System (INIS)

Karpman, G.

1978-01-01

A definition of time intervals separating two states of systems of elementary particles and observers is attempted. The definition is founded on the notion of instant state of the system and uses no information connected with the use of a clock. Applying the definition to a classical clock and to a sample of unstable particles, results are obtained in agreement with experiment. However, if the system contains 'few' elementary particles, the properties of the time interval present some different features. (author)

The Mechanics of Mechanical Watches and Clocks

CERN Document Server

Du, Ruxu

2013-01-01

"The Mechanics of Mechanical Watches and Clocks" presents historical views and mathematical models of mechanical watches and clocks. Although now over six hundred years old, mechanical watches and clocks are still popular luxury items that fascinate many people around the world. However few have examined the theory of how they work as presented in this book. The illustrations and computer animations are unique and have never been published before. It will be of significant interest to researchers in mechanical engineering, watchmakers and clockmakers, as well as people who have an engineering background and are interested in mechanical watches and clocks. It will also inspire people in other fields of science and technology, such as mechanical engineering and electronics engineering, to advance their designs. Professor Ruxu Du works at the Chinese University of Hong Kong, China. Assistant Professor Longhan Xie works at the South China University of Technology, China.

The mammalian circadian clock and its entrainment by stress and exercise.

Science.gov (United States)

Tahara, Yu; Aoyama, Shinya; Shibata, Shigenobu

2017-01-01

The mammalian circadian clock regulates day-night fluctuations in various physiological processes. The circadian clock consists of the central clock in the suprachiasmatic nucleus of the hypothalamus and peripheral clocks in peripheral tissues. External environmental cues, including light/dark cycles, food intake, stress, and exercise, provide important information for adjusting clock phases. This review focuses on stress and exercise as potent entrainment signals for both central and peripheral clocks, especially in regard to the timing of stimuli, types of stressors/exercises, and differences in the responses of rodents and humans. We suggest that the common signaling pathways of clock entrainment by stress and exercise involve sympathetic nervous activation and glucocorticoid release. Furthermore, we demonstrate that physiological responses to stress and exercise depend on time of day. Therefore, using exercise to maintain the circadian clock at an appropriate phase and amplitude might be effective for preventing obesity, diabetes, and cardiovascular disease.

Removal of cesium from simulated liquid waste with countercurrent two-stage adsorption followed by microfiltration

Energy Technology Data Exchange (ETDEWEB)

Han, Fei; Zhang, Guang-Hui [School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 (China); Gu, Ping, E-mail: guping@tju.edu.cn [School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072 (China)

2012-07-30

Highlights: Black-Right-Pointing-Pointer The adsorption isotherm of cesium by copper ferrocyanide followed a Freundlich model. Black-Right-Pointing-Pointer Decontamination factor of cesium was higher in lab-scale test than that in jar test. Black-Right-Pointing-Pointer A countercurrent two-stage adsorption-microfiltration process was achieved. Black-Right-Pointing-Pointer Cesium concentration in the effluent could be calculated. Black-Right-Pointing-Pointer It is a new cesium removal process with a higher decontamination factor. - Abstract: Copper ferrocyanide (CuFC) was used as an adsorbent to remove cesium. Jar test results showed that the adsorption capacity of CuFC was better than that of potassium zinc hexacyanoferrate. Lab-scale tests were performed by an adsorption-microfiltration process, and the mean decontamination factor (DF) was 463 when the initial cesium concentration was 101.3 {mu}g/L, the dosage of CuFC was 40 mg/L and the adsorption time was 20 min. The cesium concentration in the effluent continuously decreased with the operation time, which indicated that the used adsorbent retained its adsorption capacity. To use this capacity, experiments on a countercurrent two-stage adsorption (CTA)-microfiltration (MF) process were carried out with CuFC adsorption combined with membrane separation. A calculation method for determining the cesium concentration in the effluent was given, and batch tests in a pressure cup were performed to verify the calculated method. The results showed that the experimental values fitted well with the calculated values in the CTA-MF process. The mean DF was 1123 when the dilution factor was 0.4, the initial cesium concentration was 98.75 {mu}g/L and the dosage of CuFC and adsorption time were the same as those used in the lab-scale test. The DF obtained by CTA-MF process was more than three times higher than the single-stage adsorption in the jar test.

''First evaluation of the accuracy of a cesium cold atom fountain, perspectives''

International Nuclear Information System (INIS)

Ghezali, S.

1997-01-01

The present PHD thesis is, at first, a detailed description of the atomic cesium fountain 'FO1' working as a frequency standard since more than three years at the Laboratoire Primaire du Temps et des Frequences. The 'FO1' has been included in the calculation of the TA1 in the CCDS 1996. Then, this manuscript holds on the different effects such as cold collisions, inhomogeneities of the static magnetic field... affecting the fountain's accuracy, limited at 2.10 -15 because of the hydrogen maser (few hours of integration). The traverse velocity selection via stimulated Raman transitions at two dimensions constitute an important part of the present work. The possible improvements are discussed at the end of the manuscript. (author)

MODELING AN ION EXCHANGE PROCESS FOR CESIUM REMOVAL FROM ALKALINE RADIOACTIVE WASTE SOLUTIONS

International Nuclear Information System (INIS)

Smith, F.; Hamm, Luther; Aleman, Sebastian; Michael, Johnston

2008-01-01

The performance of spherical Resorcinol-Formaldehyde ion-exchange resin for the removal of cesium from alkaline radioactive waste solutions has been investigated through computer modeling. Cesium adsorption isotherms were obtained by fitting experimental data using a thermodynamic framework. Results show that ion-exchange is an efficient method for cesium removal from highly alkaline radioactive waste solutions. On average, two 1300 liter columns operating in series are able to treat 690,000 liters of waste with an initial cesium concentration of 0.09 mM in 11 days achieving a decontamination factor of over 50,000. The study also tested the sensitivity of ion-exchange column performance to variations in flow rate, temperature and column dimensions. Modeling results can be used to optimize design of the ion exchange system

Precision Clock Evaluation Facility

Data.gov (United States)

Federal Laboratory Consortium — FUNCTION: Tests and evaluates high-precision atomic clocks for spacecraft, ground, and mobile applications. Supports performance evaluation, environmental testing,...

Cement materials for cesium and iodine confinement

International Nuclear Information System (INIS)

Nicolas, G.; Lequeux, N.; Boch, P.; Prene, S.

2001-01-01

The following topics were dealt with: radioactive waste storage, cement materials reacting with radioactive cesium and iodine, chemical barrier formation against radioactive pollution, ceramization, long term stability, XRD, PIXE analysis

The clock paradox as a cosmological problem

International Nuclear Information System (INIS)

Fu, K.Y.

1975-01-01

In this paper the clock paradox is discussed within the framework of the general theory of relativity. It is shown that in general the aging asymmetry exists. It is also argued that the clock paradox, according to Mach's principle, is essentially a cosmological problem. (author)

Web-Based Geospatial Visualization of GPM Data with CesiumJS

Science.gov (United States)

Lammers, Matt

2018-01-01

Advancements in the capabilities of JavaScript frameworks and web browsing technology have made online visualization of large geospatial datasets such as those coming from precipitation satellites viable. These data benefit from being visualized on and above a three-dimensional surface. The open-source JavaScript framework CesiumJS (http://cesiumjs.org), developed by Analytical Graphics, Inc., leverages the WebGL protocol to do just that. This presentation will describe how CesiumJS has been used in three-dimensional visualization products developed as part of the NASA Precipitation Processing System (PPS) STORM data-order website. Existing methods of interacting with Global Precipitation Measurement (GPM) Mission data primarily focus on two-dimensional static images, whether displaying vertical slices or horizontal surface/height-level maps. These methods limit interactivity with the robust three-dimensional data coming from the GPM core satellite. Integrating the data with CesiumJS in a web-based user interface has allowed us to create the following products. We have linked with the data-order interface an on-the-fly visualization tool for any GPM/partner satellite orbit. A version of this tool also focuses on high-impact weather events. It enables viewing of combined radar and microwave-derived precipitation data on mobile devices and in a way that can be embedded into other websites. We also have used CesiumJS to visualize a method of integrating gridded precipitation data with modeled wind speeds that animates over time. Emphasis in the presentation will be placed on how a variety of technical methods were used to create these tools, and how the flexibility of the CesiumJS framework facilitates creative approaches to interact with the data.

Molecular Mechanisms Regulating Temperature Compensation of the Circadian Clock.

Science.gov (United States)

Narasimamurthy, Rajesh; Virshup, David M

2017-01-01

An approximately 24-h biological timekeeping mechanism called the circadian clock is present in virtually all light-sensitive organisms from cyanobacteria to humans. The clock system regulates our sleep-wake cycle, feeding-fasting, hormonal secretion, body temperature, and many other physiological functions. Signals from the master circadian oscillator entrain peripheral clocks using a variety of neural and hormonal signals. Even centrally controlled internal temperature fluctuations can entrain the peripheral circadian clocks. But, unlike other chemical reactions, the output of the clock system remains nearly constant with fluctuations in ambient temperature, a phenomenon known as temperature compensation. In this brief review, we focus on recent advances in our understanding of the posttranslational modifications, especially a phosphoswitch mechanism controlling the stability of PER2 and its implications for the regulation of temperature compensation.

Molecular Mechanisms Regulating Temperature Compensation of the Circadian Clock

Directory of Open Access Journals (Sweden)

David M. Virshup

2017-04-01

Full Text Available An approximately 24-h biological timekeeping mechanism called the circadian clock is present in virtually all light-sensitive organisms from cyanobacteria to humans. The clock system regulates our sleep–wake cycle, feeding–fasting, hormonal secretion, body temperature, and many other physiological functions. Signals from the master circadian oscillator entrain peripheral clocks using a variety of neural and hormonal signals. Even centrally controlled internal temperature fluctuations can entrain the peripheral circadian clocks. But, unlike other chemical reactions, the output of the clock system remains nearly constant with fluctuations in ambient temperature, a phenomenon known as temperature compensation. In this brief review, we focus on recent advances in our understanding of the posttranslational modifications, especially a phosphoswitch mechanism controlling the stability of PER2 and its implications for the regulation of temperature compensation.

An Experimental Study of the Fluorescence Spectrum of Cesium Atoms in the Presence of a Buffer Gas

Science.gov (United States)

Davydov, V. G.; Kulyasov, V. N.

2018-01-01

A direct experiment is performed to determine the quantum efficiency of a cesium fluorescence filter. The fluorescence spectra of cesium atoms are recorded under excitation of the upper states of the second resonance doublet with a Bell-Bloom cesium lamp. Introduction of different noble gases into the cell with cesium leads to the appearance of additional fluorescence photons. It is found that a fluorescence filter based on atomic cesium vapor with addition of helium in the working cell has the highest efficiency and response rate of all known fluorescence filters based on alkali-metal atomic vapors.

Solid state cesium ion guns for surface studies

International Nuclear Information System (INIS)

Souzis, A.E.; Carr, W.E.; Kim, S.I.; Seidl, M.

1990-01-01

Three cesium ion guns covering the energy range of 5--5000 V are described. These guns use a novel source of cesium ions that combine the advantages of porous metal ionizers with those of aluminosilicate emitters. Cesium ions are chemically stored in a solid electrolyte pellet and are thermionically emitted from a porous thin film of tungsten at the surface. Cesium supply to the emitting surface is controlled by applying a bias across the pellet. A total charge of 10.0 C can be extracted, corresponding to greater than 2000 h of lifetime with an extraction current of 1.0 μA. This source is compact, stable, and easy to use, and produces a beam with >99.5% purity. It requires none of the differential pumping or associated hardware necessary in designs using cesium vapor and porous tungsten ionizers. It has been used in ultrahigh-vacuum (UHV) experiments at pressures of -10 Torr with no significant gas load. Three different types of extraction optics are used depending on the energy range desired. For low-energy deposition, a simple space-charge-limited planar diode with a perveance of 1x10 -7 A/V 3/2 is used. Current densities of 10.0 μA/cm 2 at the exit aperture for energies ≤20 V are typical. This type of source provides an alternative to vapor deposition with the advantage of precise flux calibration by integration of the ion current. For energies from 50 to 500 V and typical beam radii of 0.5 to 0.2 mm, a high perveance Pierce-type ion gun is used. This gun was designed with a perveance of 1x10 -9 A/V 3/2 and produces a beam with an effective temperature of 0.35 eV. For the energy range of 0.5 to 5 keV, the Pierce gun is used in conjunction with two Einzel lenses, enabling a large range of imaging ratios to be obtained. Beam radii of 60 to 300 μm are typical for beam currents of 50 nA to 1.0 μA

Historical Cost Curves for Hydrogen Masers and Cesium Beam Frequency and Timing Standards

Science.gov (United States)

Remer, D. S.; Moore, R. C.

1985-01-01

Historical cost curves were developed for hydrogen masers and cesium beam standards used for frequency and timing calibration in the Deep Space Network. These curves may be used to calculate the cost of future hydrogen masers or cesium beam standards in either future or current dollars. The cesium beam standards are decreasing in cost by about 2.3% per year since 1966, and hydrogen masers are decreasing by about 0.8% per year since 1978 relative to the National Aeronautics and Space Administration inflation index.

Effects of mineralogy on sorption of strontium and cesium onto Calico Hills Tuff

International Nuclear Information System (INIS)

Meyer, R.E.; Arnold, W.D.; Case, F.I.; O'Kelley, G.D.; Land, J.F.

1990-04-01

The sorption properties of tuff formations at the proposed site for the high-level nuclear waste repository at Yucca Mountain, Nevada, have been extensively studied. Sorption and desorption measurements were made of strontium and cesium onto clinoptilolite and Calico Hills Tuff. The object was to see whether there was a correlation between sorption of strontium and cesium onto Calico Hills Tuff and the sorption of strontium and cesium onto clinoptilolite based on the content of clinoptilolite in the Calico Hills Tuff. 13 refs., 10 figs., 6 tabs

The Molecular Circadian Clock and Alcohol-Induced Liver Injury

Directory of Open Access Journals (Sweden)

Uduak S. Udoh

2015-10-01

Full Text Available Emerging evidence from both experimental animal studies and clinical human investigations demonstrates strong connections among circadian processes, alcohol use, and alcohol-induced tissue injury. Components of the circadian clock have been shown to influence the pathophysiological effects of alcohol. Conversely, alcohol may alter the expression of circadian clock genes and the rhythmic behavioral and metabolic processes they regulate. Therefore, we propose that alcohol-mediated disruption in circadian rhythms likely underpins many adverse health effects of alcohol that cut across multiple organ systems. In this review, we provide an overview of the circadian clock mechanism and showcase results from new studies in the alcohol field implicating the circadian clock as a key target of alcohol action and toxicity in the liver. We discuss various molecular events through which alcohol may work to negatively impact circadian clock-mediated processes in the liver, and contribute to tissue pathology. Illuminating the mechanistic connections between the circadian clock and alcohol will be critical to the development of new preventative and pharmacological treatments for alcohol use disorders and alcohol-mediated organ diseases.

Cesium-137 in biota from the Bothnian sea after the Chernobyl accident

International Nuclear Information System (INIS)

Notter, M.

1990-01-01

The Chernobyl fallout in April 1986 hit the Swedish Bothnian Sea coast to a relatively large extent. Extended sampling programs to follow uptake and mobilization of Cs-137 at different trophic levels in the aquatic environment started immediately after the accident. Water, sediment, algae, fish and food organisms for fish have regularly been sampled during 1986 and 1988. The highest cesium concentration (3400 Bq/m 3 ) in water from the Bothnian sea was detected in May-July 1986. Since September 1986 the cesium concentration has been decreasing and was about 500 Bq/m 3 in March-June 1987. During the same period, green algae (Cladophora), from early top values at 17000 Bq/kg d.w., have rapidly decreased to about 200 Bq/kg d.w. Of the investigated food organisms, fish-spawn rapidly got high values (3000 Bq/kg d.w.) of cesium. There is also reason to believe that this was the case for plankton. The cesium concentration on the other food organisms was lower, about (500-1200 Bq/kg d.w.). The decrease was fast and already during August 1986 they had relatively low concentrations (less than 500 Bq/kg d.w.). The cesium metabolism was rapid in species that feed on plankton and filtered material from the pelagial, such as mussles and herring. The maximum concentration was reached (1000-1500 Bq/kg d.w.) in September 1986. Fish species with algae in the nutrient chain (e.g. roach) reached concentrations of about 1000 Bq/kg d.w. and the decrease is slower. The accessible cesium for prey fish became relatively good depending on the high concentrations in fish-spawn. The maximum value for the cesium concentration in perch and pike was 2000-3000 Bq/kg d.w. and the decrease is slow. From the results from late 1988 the concentration factor (CF) has been calculated for several fish species in brackish water

Clocks do not tick in unison: isolation of Clock and vrille shed new light on the clockwork model of the sand fly Lutzomyia longipalpis.

Science.gov (United States)

Gesto, João Silveira Moledo; Rivas, Gustavo Bueno da Silva; Pavan, Marcio Galvão; Meireles-Filho, Antonio Carlos Alves; Amoretty, Paulo Roberto de; Souza, Nataly Araújo de; Bruno, Rafaela Vieira; Peixoto, Alexandre Afranio

2015-10-06

Behavior rhythms of insect vectors directly interfere with the dynamics of pathogen transmission to humans. The sand fly Lutzomyia longipalpis is the main vector of visceral leishmaniasis in America and concentrates its activity around dusk. Despite the accumulation of behavioral data, very little is known about the molecular bases of the clock mechanism in this species. This study aims to characterize, within an evolutionary perspective, two important circadian clock genes, Clock and vrille. We have cloned and isolated the coding sequence of L. longipalpis' genes Clock and vrille. The former is structured in eight exons and encodes a protein of 696 amino acids, and the latter comprises three exons and translates to a protein of 469 amino acids. When compared to other insects' orthologues, L. longipalpis CLOCK shows a high degree of conservation in the functional domains bHLH and PAS, but a much shorter glutamine-rich (poly-Q) C-terminal region. As for L. longipalpis VRILLE, a high degree of conservation was found in the bZIP domain. To support these observations and provide an elegant view of the evolution of both genes in insects, phylogenetic analyses based on maximum-likelihood and Bayesian inferences were performed, corroborating the previously known insect systematics. The isolation and phylogenetic analyses of Clock and vrille orthologues in L. longipalpis bring novel and important data to characterize this species' circadian clock. Interestingly, the poly-Q shortening observed in CLOCK suggests that its transcription activity might be impaired and we speculate if this effect could be compensated by other clock factors such as CYCLE.

Reduced Kalman Filters for Clock Ensembles

Science.gov (United States)

Greenhall, Charles A.

2011-01-01

This paper summarizes the author's work ontimescales based on Kalman filters that act upon the clock comparisons. The natural Kalman timescale algorithm tends to optimize long-term timescale stability at the expense of short-term stability. By subjecting each post-measurement error covariance matrix to a non-transparent reduction operation, one obtains corrected clocks with improved short-term stability and little sacrifice of long-term stability.

The role of biological clock in glucose homeostasis 

Directory of Open Access Journals (Sweden)

Piotr Chrościcki

2013-06-01

Full Text Available The mechanism of the biological clock is based on a rhythmic expression of clock genes and clock-controlled genes. As a result of their transcripto-translational associations, endogenous rhythms in the synthesis of key proteins of various physiological and metabolic processes are created. The major timekeeping mechanism for these rhythms exists in the central nervous system. The master circadian clock, localized in suprachiasmatic nucleus (SCN, regulates multiple metabolic pathways, while feeding behavior and metabolite availability can in turn regulate the circadian clock. It is also suggested that in the brain there is a food entrainable oscillator (FEO or oscillators, resulting in activation of both food anticipatory activity and hormone secretion that control digestion processes. Moreover, most cells and tissues express autonomous clocks. Maintenance of the glucose homeostasis is particularly important for the proper function of the body, as this sugar is the main source of energy for the brain, retina, erythrocytes and skeletal muscles. Thus, glucose production and utilization are synchronized in time. The hypothalamic excited orexin neurons control energy balance of organism and modulate the glucose production and utilization. Deficiency of orexin action results in narcolepsy and weight gain, whereas glucose and amino acids can affect activity of the orexin cells. Large-scale genetic studies in rodents and humans provide evidence for the involvement of disrupted clock gene expression rhythms in the pathogenesis of obesity and type 2 diabetes. In general, the current lifestyle of the developed modern societies disturbs the action of biological clock. 

Clock face drawing test performance in children with ADHD.

Science.gov (United States)

Ghanizadeh, Ahmad; Safavi, Salar; Berk, Michael

2013-01-01

The utility and discriminatory pattern of the clock face drawing test in ADHD is unclear. This study therefore compared Clock Face Drawing test performance in children with ADHD and controls. 95 school children with ADHD and 191 other children were matched for gender ratio and age. ADHD symptoms severities were assessed using DSM-IV ADHD checklist and their intellectual functioning was assessed. The participants completed three clock-drawing tasks, and the following four functions were assessed: Contour score, Numbers score, Hands setting score, and Center score. All the subscales scores of the three clock drawing tests of the ADHD group were lower than that of the control group. In ADHD children, inattention and hyperactivity/ impulsivity scores were not related to free drawn clock test scores. When pre-drawn contour test was performed, inattentiveness score was statistically associated with Number score while none of the other variables of age, gender, intellectual functioning, and hand use preference were associated with that kind of score. In pre-drawn clock, no association of ADHD symptoms with any CDT subscales found significant. In addition, more errors are observed with free drawn clock and Pre-drawn contour than pre-drawn clock. Putting Numbers and Hands setting are more sensitive measures to screen ADHD than Contour and Center drawing. Test performance, except Hands setting, may have already reached a developmental plateau. It is probable that Hand setting deficit in children with ADHD may not decrease from age 8 to 14 years. Performance of children with ADHD is associated with complexity of CDT.

Cesium-137 uptake studies on ammonium phospho molybdate irradiated with electrons

International Nuclear Information System (INIS)

Rao, K.L.N.; Balasubramanian, K.R.; Shukla, J.P.

1992-01-01

Ammonium phospho molybdate is an important inorganic ion exchanger having high selectivity for cesium. This paper discusses the effects of electron irradiation to a dose of 1 mGy on this exchanger with special reference to its ion exchange performance using cesium-137 as a tracer. An explanation is attempted for the slight increase in the distribution coefficients. (author). 5 refs., 1 tab

Neurogenetics of Drosophila circadian clock: expect the unexpected.

Science.gov (United States)

Jarabo, Patricia; Martin, Francisco A

2017-12-01

Daily biological rhythms (i.e. circadian) are a fundamental part of animal behavior. Numerous reports have shown disruptions of the biological clock in neurodegenerative disorders and cancer. In the latter case, only recently we have gained insight into the molecular mechanisms. After 45 years of intense study of the circadian rhtythms, we find surprising similarities among species on the molecular clock that governs biological rhythms. Indeed, Drosophila is one of the most widely used models in the study of chronobiology. Recent studies in the fruit fly have revealed unpredicted roles for the clock machinery in different aspects of behavior and physiology. Not only the central pacemaker cells do have non-classical circadian functions but also circadian genes work in other cells and tissues different from central clock neurons. In this review, we summarize these new evidences. We also recapitulate the most basic features of Drosophila circadian clock, including recent data about the inputs and outputs that connect the central pacemaker with other regions of the brain. Finally, we discuss the advantages and drawbacks of using natural versus laboratory conditions.

Strontium-90 and cesium-137 in sea sediments (from May 1984 to Sep 1984)

International Nuclear Information System (INIS)

1984-01-01

Strontium-90 and cesium-137 monitoring results are presented for sea sediment samples of 12 sampling points located all over Japan from Tomari, Hokkaido to Kinnakagusuku Bay, Okinawa. The samples were collected by considering of enough sea water depth, no significant sedimental movement and sediment characteristics, and by employing a conventional sampling device. Approximately 4 kg-wet sample was dried and was passed through a 20 cm mesh sieve. After adding of strontium and cesium carriers, strontium-90 and cesium-137 were leached with a hot hydrochloric acid solution. The leachate was treated by ion exchange and coprecipitation to concentrate and isolate strontium-90 or cesium-137. Radiation counting was carried out by employing a low background beta counter usually for 60 minutes for the samples of strontium carbonate or cesium chloroplatinate. Determined strontium-90 contents in sea sediment were distributed from 0 +- 2.7 pCi/kg-dry (Mutsu Bay, Aomori, Yamaguchi Bay, Yamaguchi) to 14 +- 3.2 pCi/kg-dry (Mutsu Bay), and those of cesium-137 were from 9 +- 3.5 pCi/kg-dry (Mutsu Bay) to 250 +- 9 pCi/kg-dry (Off-Niigata Port, Niigata). Local variation of the contents of these radionuclides was very large, and for seasonal variation, it was also found large for the both nuclides content in the Mutsu Bay samples of May, 1984 and August 1984, as for strontium-90, 0 +- 2.7 pCi/kg and 14 +- 3.2 pCi/kg, for cesium-137, 9 +- 3.5 pCi/kg and 200 +- 8 pCi/kg, respectively. (Takagi, S.)

Studies of cesium and strontium migration in unconsolidated Canadian geological materials

International Nuclear Information System (INIS)

Gillham, R.W.; Lindsay, L.E.; Reynolds, W.D.; Kewen, T.J.; Cherry, J.A.; Reddy, M.R.

1981-06-01

Distribution coefficients (Ksub(d)) were measured for cesium and strontium in 16 samples of Canadian unconsolidated geological materials. The samples were collected to cover a wide range of grain size, clay-mineral composition, cation exchange capacity and carbonate mineral content. Distribution coefficients ranged between 10 2 and 2.0 x 10 4 ml/g for cesium and between 2.5 and 10 2 ml/g for strontium, indicating that most unconsolidated geological materials have a substantial ability to retard the migration of cesium, while strontium could generally be expected to be somewhat more mobile. The measured K values were not significantly correlated with the measured soil properties, but appeared to be significantly affected by the background concentration of stable isotopes of the respective radionuclides

Transfer of radio-cesium from forest soil to woodchips using fungal activities

Science.gov (United States)

Kaneko, Nobuhiro; Huang, Yao; Tanaka, Yoichiro; Fujiwara, Yoshihiro; Sasaki, Michiko; Toda, Hiroto; Takahashi, Terumasa; Kobayashi, Tatsuaki; Harada, Naoki; Nonaka, Masahiro

2014-05-01

Raido-cesium released to terrestrial ecosystems by nuclear accidents is know to accumulate forest soil and organic layer on the soil. Forests in Japan are not exceptions. Practically it is impossible to decontaminate large area of forests. However, there is a strong demand from local people, who has been using secondary forests (Satoyama) around croplands in hilly areas, to decontaminate radio-cesium, because those people used to collect wild mushrooms and edible plants, and there are active cultures of mushrooms using logs and sawdusts. These natural resource uses consist substantial part of their economical activities, Therefore it is needed to decontaminate some selected part of forests in Japan to local economy. Clear cutting and scraping surface soil and organic matter are common methods of decontamination. However the efficiency of decontamination is up to 30% reduction of aerial radiation, and the cost to preserve contaminated debris is not affordable. In this study we used wood chips as a growth media for saprotrophic fungi which are known to accumulate redio-cesium. There are many studies indicated that mushrooms accumulated redio-cesium from forest soil and organic layer. It is not practical to collect mushrooms to decontaminate redio-cesium, because biomass of mushrooms are not enough to collect total contaminants. Mushrooms are only minor part of saprotrophic fungi. Fungal biomass in forest soil is about 1% of dead organic matter on forest floor. Our previous study to observe Cs accumulation to decomposing leaf litter indicated 18% absorption of total soil radio-Cs to litter during one year field incubation (Kaneko et al., 2013), and Cs concentration was proportional to fungal biomass on litter. This result indicated that fungi transferred radio-cesium around newly supplied leaf litter free of contamination. Therefore effective decontamination will be possible if we can provide large amount of growth media for saprotrophic fungi, and the media can be

A solution for cesium removal from high-salinity acidic or alkaline liquid waste: The crown calix[4]arenes

International Nuclear Information System (INIS)

Dozol, J.F.; Simon, N.; Lamare, V.; Rouquette, H.; Eymard, S.; Tournois, B.; Marc, D. de; Macias, R.M.

1999-01-01

Calix[4]arenes monocrown or biscrown, blocked in 1,3 alternative cone conformation, display an exceptional efficiency for cesium extraction, even from very acid or alkaline media. Moreover, they possess an important selectivity for cesium over sodium that makes possible the extraction of cesium from media containing high sodium nitrate loadings. Another advantage, since the extraction of cesium is reversible, is that the stripping of cesium can be carried out in deionized water, a property which leads to very high concentration factors. 79 refs., 10 figs., 6 tabs

Circadian clock components in the rat neocortex

DEFF Research Database (Denmark)

Rath, Martin Fredensborg; Rohde, Kristian; Fahrenkrug, Jan

2013-01-01

in the rat neocortex. Among these, Per1, Per2, Per3, Cry1, Bmal1, Nr1d1 and Dbp were found to exhibit daily rhythms. The amplitude of circadian oscillation in neocortical clock gene expression was damped and the peak delayed as compared with the SCN. Lesions of the SCN revealed that rhythmic clock gene...... expression in the neocortex is dependent on the SCN. In situ hybridization and immunohistochemistry showed that products of the canonical clock gene Per2 are located in perikarya throughout all areas of the neocortex. These findings show that local circadian oscillators driven by the SCN reside within...... neurons of the neocortex....

Measurements of cesium-137 in residents of Seascale and its environs

Energy Technology Data Exchange (ETDEWEB)

Fry, F A; Sumerling, T J

1984-07-01

Measurements of the body content of cesium-137 have been made on almost 300 members of the public residing in or near Seascale, a community in west Cumbria close to the nuclear installation at Sellafield operated by British Nuclear Fuels plc. The major objective of this study was to compare the levels found in the population with those predicted from environmental measurements. No artificially-produced radionuclides were detected in the overwhelming majority of those measured. Cesium-137 was detected in about 7% of the measured population but, in general, the levels were much lower than those expected. The highest body content found was comparable with the average predicted from environmental measurements and estimates of food consumption rates; this body content corresponds to intake of cesium-137 at a rate of somewhat less than 2% of the appropriate annual limit on intake for members of the public. From this study, it is concluded that contamination of foodstuffs with cesium-137 leads to exposure of the local population at levels that are of low radiological significance, and that estimates of intake obtained from environmental monitoring data are cautious for most of the population.

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

Energy Technology Data Exchange (ETDEWEB)

Hu, Baiyang [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Fugetsu, Bunshi, E-mail: hu@ees.hokudai.ac.jp [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Yu, Hongwen [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Abe, Yoshiteru [Kyoei Engineering Corporation, Niigata 959-1961 (Japan)

2012-05-30

Highlights: Black-Right-Pointing-Pointer Prussian blue was sealed in cavities of diatomite using carbon nanotubes. Black-Right-Pointing-Pointer The caged Prussian blue after being permanently immobilized in polyurethane spongy showed a 167 mg/g capability for absorbing cesium. Black-Right-Pointing-Pointer Cesium elimination was accomplished by simply adding the Prussian-blue based spongiform adsorbent to radioactive water. - Abstract: We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent.

Environmental application of cesium-137 irradiation technology: sludges and foods

International Nuclear Information System (INIS)

Sivinski, J.S.

1983-01-01

Several activities have been undertaken to investigate and implement the use of the military byproduct cesium-137 in ways which benefit mankind. Gamma radiation from cesium-137 has been shown to be effective in reducing pathogens in sewage sludge to levels where reuse of the material in public areas meets current regulatory criteria for protection of public health. Food irradiation at doses of 10 kGy or less have been found by international expert committees to be wholesome and safe for human consumption. Cesium-137 can be used as a means of enhancing particular properties of various food commodities by means of sterilization, insect disinfestation, delayed senescence and ripening, and sprout inhibition. This paper discusses the U.S. Department of Energy Beneficial Uses Program research and engineering history, as well as current activities and future plans, relating to both sewage sludge and food irradiation. (author)

Environmental application of cesium-137 irradiation technology: Sludges and foods

Science.gov (United States)

Sivinski, Jacek S.

Several activities have been undertaken to investigate and implement the use of the military byproduct cesium-137 in ways which benefit mankind. Gamma radiation from cesium-137 has been shown to be effective in reducing pathogens in sewage sludge to levels where reuse of the material in public areas meets current regulatory criteria for protection of public health. Food irradiation at doses of 10 kGy or less have been found by international expert committees to be wholesome and safe for human consumption. Cesium-137 can be used as a means of enhancing particular properties of various food commodities by means of sterilization, insect disinfestation, delayed senescence and ripening, and sprout inhibition. This paper discusses the U.S. Department of Energy Beneficial Uses Program research and engineering history, as well as current activities and future plans, relating to both sewage sludge and food irradiation.

Tungstate-based glass-ceramics for the immobilization of radio cesium

Science.gov (United States)

Drabarek, Elizabeth; McLeod, Terry I.; Hanna, John V.; Griffith, Christopher S.; Luca, Vittorio

2009-02-01

The preparation of tungstate-containing glass-ceramic composites (GCC) for the potential immobilization of radio cesium has been considered. The GCC materials were prepared by blending two oxide precursor compositions in various proportions. These included a preformed Cs-containing hexagonal tungsten bronze (HTB) phase (Cs 0.3Ti 0.2W 0.8O 3, P6 3/ mcm) and a blend of silica and other oxides. The use of the HTB phase was motivated on the assumption that a HTB-based adsorbent could be used to remove cesium directly from aqueous high level liquid waste feeds. In the absence of the HTB, glass-ceramics were relatively easily prepared from the Cs-containing glass-forming oxide blend. On melting the mixture a relative complex GCC phase assemblage formed. The principal components of this phase assemblage were determined using X-ray powder diffraction, 133Cs MAS-NMR, and cross-sectional SEM and included glass, various zeolites, scheelite (CaWO 4) and a range of other oxide phases and Cs-containing aluminosilicate. Importantly, under no circumstance was cesium partitioned into the glass phase irrespective of whether or not the composition included the preformed Cs-containing HTB compound. For compositions containing the HTB, cesium was partitioned into one of four major phases including zeolite; Cs-silica-tungstate bronze, pollucite (CsAlSi 2O 6), and an aluminosilicate with an Al/Si ratio close to one. The leach resistance of all materials was evaluated and related to the cesium distribution within the GCC phase assemblages. In general, the GCCs prepared from the HTB had superior durability compared with materials not containing tungsten. Indeed the compositions in many cases had leach resistances comparable to the best ceramics or glass materials.

Clock Face Drawing Test Performance in Children with ADHD

Directory of Open Access Journals (Sweden)

Ahmad Ghanizadeh

2013-01-01

Full Text Available  Introduction: The utility and discriminatory pattern of the clock face drawing test in ADHD is unclear. This study therefore compared Clock Face Drawing test performance in children with ADHD and controls.   Material & methods: 95 children with ADHD and 191 school children were matched for gender ratio and age. ADHD symptoms severities were assessed using DSM-IV ADHD checklist and their intellectual functioning was assessed. The participants completed three clock-drawing tasks, and the following four functions were assessed: Contour score, Numbers score, Hands setting score, and Center score    Results: All the subscales scores of the three clock drawing tests of the ADHD group were lower than that of the control group. In ADHD children, inattention and hyperactivity/impulsivity scores were not related with free drawn clock test scores. When pre-drawn contour test was performed, inattentiveness score was statistically associated with Number score. None of the other variables of age, gender, intellectual functioning, and hand use preference were associated with Numbers score. In pre-drawn clock, no association of ADHD symptoms with any CDT subscales was significant. In addition, more errors are observed with free drawn clock and Pre-drawn contour than pre-drawn clock.    Conclusion: Putting Numbers and Hands setting are more sensitive measures to screen ADHD than Contour and Center drawing. Test performance, except Hands setting, may have already reached a developmental plateau. It is probable that Hand setting deficit in children with ADHD may not decrease from age 8 to 14 years. Performance of children with ADHD is associated with the complexity of CDT.

Measurement of parity violation in the 6S-7S transition of cesium using stimulated emission; Mesure de la violation de la parite sur la transition 6S-7S du cesium par emission stimulee dans une vapeur atomique

Energy Technology Data Exchange (ETDEWEB)

Lintz, M

2005-11-15

This document describes the design and implementation of a pump-probe polarimetry experiment in a cesium vapor, aiming at a 1% precision measurement of atomic parity violation (APV) induced by Z{sup 0} boson exchange. The experimental scheme, relying on induced emission by a probe laser, allows a detection efficiency close to unity, and the left-right asymmetry to be measured is amplified during the propagation of the probe beam in the excited vapour. The interest of the result presented here is to cross-check the unique previous result by an experiment with a completely different design, and hence with completely different systematics, that also allows measurements on long-lived isotopes especially {sup 135}Cs (nuclear spin 7/2 like {sup 133}Cs, half-life 3 million years). We have demonstrated improvements in polarimetry techniques (rejection of instrumental errors, implementation of a polarization magnifier), especially in pulsed polarimetry (doubly-differential, balanced-mode polarization analysis). But most importantly, the expected pump-probe chiral optical gain has been observed in a Cs vapor. The precision on the {theta}{sup pv} measurement has been improved to 2.6%, and the achieved signal/noise ratio allows measurements at the 1% precision level. The achieved precision on lm E{sub 1}{sup pv} is 2 x 10{sup -13} ea{sub 0}, 15 times better than the measurements obtained with the lead and thallium atoms. Our result is in agreement with the more precise Boulder result. The required amount of cesium is small enough to allow a measurement with {sup 135}Cs provided one takes reasonable radioprotection measures. (author)

SIMS diagnostics of nanometer semiconductor structures with the use of cesium ions

International Nuclear Information System (INIS)

Pustovit, A.N.; Vyatkin, A.F.

2006-01-01

The modernization of cesium ion source was carried out to increase the lifetime, the power range of primary ions and temporary stability of primary ion beam. The elements depth profiles obtained with the help of primary cesium ions and primary iodine ions are in good agreement with transmission electron microscopy data [ru

A central role for ubiquitination within a circadian clock protein modification code

Directory of Open Access Journals (Sweden)

Katarina eStojkovic

2014-08-01

Full Text Available Circadian rhythms, endogenous cycles of about 24 h in physiology, are generated by a master clock located in the suprachiasmatic nucleus of the hypothalamus and other clocks located in the brain and peripheral tissues. Circadian disruption is known to increase the incidence of various illnesses, such as mental disorders, metabolic syndrome and cancer. At the molecular level, periodicity is established by a set of clock genes via autoregulatory translation-transcription feedback loops. This clock mechanism is regulated by post-translational modifications such as phosphorylation and ubiquitination, which set the pace of the clock. Ubiquitination in particular has been found to regulate the stability of core clock components, but also other clock protein functions. Mutation of genes encoding ubiquitin ligases can cause either elongation or shortening of the endogenous circadian period. Recent research has also started to uncover roles for deubiquitination in the molecular clockwork. Here we review the role of the ubiquitin pathway in regulating the circadian clock and we propose that ubiquitination is a key element in a clock protein modification code that orchestrates clock mechanisms and circadian behavior over the daily cycle.

Redox rhythm reinforces the circadian clock to gate immune response.

Science.gov (United States)

Zhou, Mian; Wang, Wei; Karapetyan, Sargis; Mwimba, Musoki; Marqués, Jorge; Buchler, Nicolas E; Dong, Xinnian

2015-07-23

Recent studies have shown that in addition to the transcriptional circadian clock, many organisms, including Arabidopsis, have a circadian redox rhythm driven by the organism's metabolic activities. It has been hypothesized that the redox rhythm is linked to the circadian clock, but the mechanism and the biological significance of this link have only begun to be investigated. Here we report that the master immune regulator NPR1 (non-expressor of pathogenesis-related gene 1) of Arabidopsis is a sensor of the plant's redox state and regulates transcription of core circadian clock genes even in the absence of pathogen challenge. Surprisingly, acute perturbation in the redox status triggered by the immune signal salicylic acid does not compromise the circadian clock but rather leads to its reinforcement. Mathematical modelling and subsequent experiments show that NPR1 reinforces the circadian clock without changing the period by regulating both the morning and the evening clock genes. This balanced network architecture helps plants gate their immune responses towards the morning and minimize costs on growth at night. Our study demonstrates how a sensitive redox rhythm interacts with a robust circadian clock to ensure proper responsiveness to environmental stimuli without compromising fitness of the organism.

Ion-exchange properties of cesium and strontium into zeolites from sodium salt solutions

International Nuclear Information System (INIS)

Kanno, Takuji; Hashimoto, Hiroyuki; Ohtani, Tozo.

1978-01-01

The ion-exchange properties of cesium and strontium into zeolite from sodium salt solution has been studied in zeolite A, zeolite X, zeolite Y, mordenite and clinoptilolite. The distribution of cesium into mordenite from about 1 -- 2 M sodium chloride and sodium hydroxide solutions is considerably larger than that into zeolite A. The distribution coefficient for 2 M solution of sodium salts was about 300. Therefore, the separation of cesium from sodium salt solution is possible by using mordenite. The distribution of strontium into zeolites form 1 -- 2 M solutions of sodium chloride and sodium nitrate were in the order of zeolite A>zeolite X>zeolite Y asymptoticaly equals mordenite. The distribution coefficient of 230 was obtained for 1 M solutions of sodium salts. The anion in solutions had no effect on the distribution of cesium and strontium into zeolite from sodium salt solution. (author)

Validation and Application of Concentrated Cesium Eluate Physical Property Models

International Nuclear Information System (INIS)

Choi, A.S.

2004-01-01

This work contained two objectives. To verify the mathematical equations developed for the physical properties of concentrated cesium eluate solutions against experimental test results obtained with simulated feeds. To estimate the physical properties of the radioactive AW-101 cesium eluate at saturation using the validated models. The Hanford River Protection Project (RPP) Hanford Waste Treatment and Immobilization Plant (WTP) is currently being built to extract radioisotopes from the vast inventory of Hanford tank wastes and immobilize them in a silicate glass matrix for eventual disposal at a geological repository. The baseline flowsheet for the pretreatment of supernatant liquid wastes includes removal of cesium using regenerative ion-exchange resins. The loaded cesium ion-exchange columns will be eluted with nitric acid nominally at 0.5 molar, and the resulting eluate solution will be concentrated in a forced-convection evaporator to reduce the storage volume and to recover the acid for reuse. The reboiler pot is initially charged with a concentrated nitric acid solution and kept under a controlled vacuum during feeding so the pot contents would boil at 50 degrees Celsius. The liquid level in the pot is maintained constant by controlling both the feed and boilup rates. The feeding will continue with no bottom removal until the solution in the pot reaches the target endpoint of 80 per cent saturation with respect to any one of the major salt species present

Microwave-to-optical frequency conversion using a cesium atom coupled to a superconducting resonator

Science.gov (United States)

Gard, Bryan T.; Jacobs, Kurt; McDermott, R.; Saffman, M.

2017-07-01

A candidate for converting quantum information from microwave to optical frequencies is the use of a single atom that interacts with a superconducting microwave resonator on one hand and an optical cavity on the other. The large electric dipole moments and microwave transition frequencies possessed by Rydberg states allow them to couple strongly to superconducting devices. Lasers can then be used to connect a Rydberg transition to an optical transition to realize the conversion. Since the fundamental source of noise in this process is spontaneous emission from the atomic levels, the resulting control problem involves choosing the pulse shapes of the driving lasers so as to maximize the transfer rate while minimizing this loss. Here we consider the concrete example of a cesium atom, along with two specific choices for the levels to be used in the conversion cycle. Under the assumption that spontaneous emission is the only significant source of errors, we use numerical optimization to determine the likely rates for reliable quantum communication that could be achieved with this device. These rates are on the order of a few megaqubits per second.

Molecular Mechanisms Regulating Temperature Compensation of the Circadian Clock

OpenAIRE

David M. Virshup; Rajesh Narasimamurthy

2017-01-01

An approximately 24-h biological timekeeping mechanism called the circadian clock is present in virtually all light-sensitive organisms from cyanobacteria to humans. The clock system regulates our sleep–wake cycle, feeding–fasting, hormonal secretion, body temperature, and many other physiological functions. Signals from the master circadian oscillator entrain peripheral clocks using a variety of neural and hormonal signals. Even centrally controlled internal temperature fluctuations can entr...

Hanle Detection for Optical Clocks

Directory of Open Access Journals (Sweden)

Xiaogang Zhang

2015-01-01

Full Text Available Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard.

OMEGA SYSTEM SYNCHRONIZATION.

Science.gov (United States)

TIME SIGNALS, * SYNCHRONIZATION (ELECTRONICS)), NETWORKS, FREQUENCY, STANDARDS, RADIO SIGNALS, ERRORS, VERY LOW FREQUENCY, PROPAGATION, ACCURACY, ATOMIC CLOCKS, CESIUM, RADIO STATIONS, NAVAL SHORE FACILITIES

Minimal tool set for a prokaryotic circadian clock.

Science.gov (United States)

Schmelling, Nicolas M; Lehmann, Robert; Chaudhury, Paushali; Beck, Christian; Albers, Sonja-Verena; Axmann, Ilka M; Wiegard, Anika

2017-07-21

Circadian clocks are found in organisms of almost all domains including photosynthetic Cyanobacteria, whereby large diversity exists within the protein components involved. In the model cyanobacterium Synechococcus elongatus PCC 7942 circadian rhythms are driven by a unique KaiABC protein clock, which is embedded in a network of input and output factors. Homologous proteins to the KaiABC clock have been observed in Bacteria and Archaea, where evidence for circadian behavior in these domains is accumulating. However, interaction and function of non-cyanobacterial Kai-proteins as well as homologous input and output components remain mainly unclear. Using a universal BLAST analyses, we identified putative KaiC-based timing systems in organisms outside as well as variations within Cyanobacteria. A systematic analyses of publicly available microarray data elucidated interesting variations in circadian gene expression between different cyanobacterial strains, which might be correlated to the diversity of genome encoded clock components. Based on statistical analyses of co-occurrences of the clock components homologous to Synechococcus elongatus PCC 7942, we propose putative networks of reduced and fully functional clock systems. Further, we studied KaiC sequence conservation to determine functionally important regions of diverged KaiC homologs. Biochemical characterization of exemplary cyanobacterial KaiC proteins as well as homologs from two thermophilic Archaea demonstrated that kinase activity is always present. However, a KaiA-mediated phosphorylation is only detectable in KaiC1 orthologs. Our analysis of 11,264 genomes clearly demonstrates that components of the Synechococcus elongatus PCC 7942 circadian clock are present in Bacteria and Archaea. However, all components are less abundant in other organisms than Cyanobacteria and KaiA, Pex, LdpA, and CdpA are only present in the latter. Thus, only reduced KaiBC-based or even simpler, solely KaiC-based timing systems

Kinetics of 137cesium in cerebral structures and blood

International Nuclear Information System (INIS)

Ribas, B.; Gonzalez, M.D.; Rio, J. del; Reus, M.I.S.; Gonzalez-Baron, M.

1987-01-01

The old clinical use of cesium in epilepsy expresses a relation of this metal with the central nervous system. Two groups of male Wistar rats of 200 g were administered single doses of 50μCi intravenously for blood kinetics and 2μCi 137 CsCl in each lateral ventricle of the brain for the kinetics in the cerebral structures, respectively. In both cases under ether anesthesia. Blood samples of IV gouts were weighed, and cerebral structure hypothalamus, hypocampus, striatum, cortex, cerebellum, mesencephalon and medulla oblongata dissected, cleaned, washed, dried, weighed, and in both cases cpm of the samples evaluated submitting it to the gamma radiations detector. In both experimental values of the 137 CsCl kinetics are expressed and applying the retroprojection method; parameters and constants are obtained. tsub(1/2) alpha = 0.0358 h and tsub(1/2) beta = 6.7159 h. In tables the equations of the alpha and beta phases are expressed. In blood after the rapid diminution of the radioactivity in the first 5 min the equilibrium phase is reached in 30 min afterwards, and the values remain almost the same 4 h after the injection and cesium is slowly eliminated by the rat. Cerebral structures after its intracerebroventricular application show that cesium has a great uptake velocity, it is rapidly incorporated by hypothalamus and after by cortex, hypocampus, striatum, mesencephalon and medulla oblongata, the two last showing the slower incorporation. After 24 h the cesium radioactivity declines slowly and progressively. (author)

Release and transport of fission product cesium in the TMI-2 accident

International Nuclear Information System (INIS)

Lorenz, R.A.; Collins, J.L.

1986-01-01

Approximately 50% of the fission product cesium was released from the overheated UO 2 fuel in the TMI-2 accident. Steam that boiled away from a water pool in the bottom of the reactor vessel transported the released fission products throughout the reactor coolant system (RCS). Some fission products passed directly through a leaking valve with steam and water into the containment structure, but most deposited on dry surfaces inside of the RCS before being dissolved or resuspended when the RCS was refilled with water. A cesium transport model was developed that extended measured cesium in the RCS back to the first day of the accident. The model revealed that ∼62% of the released 137 Cs deposited on dry surfaces inside of the RCS before being slowly leached and transported out of the RCS in leaked or letdown water. The leach rates from the model agreed reasonably well with those measured in the laboratory. The chemical behavior of cesium in the TMI-2 accident agreed with that observed in fission product release tests at Oak Ridge National Laboratory (ORNL)

New sources of cold atoms for atomic clocks

International Nuclear Information System (INIS)

Aucouturier, E.

1997-01-01

The purpose of this doctoral work is the realisation of new sources of cold cesium atoms that could be useful for the conception of a compact and high-performance atomic clock. It is based on experiences of atomic physics using light induced atomic manipulation. We present here the experiences of radiative cooling of atoms that have been realised at the Laboratoire de l'Horloge Atomique from 1993 to 1996. Firstly, we applied the techniques of radiative cooling and trapping of atoms in order to create a three-dimensional magneto-optical trap. For this first experience, we developed high quality laser sources, that were used for other experiments. We imagined a new configuration of trapping (two-dimensional magneto-optical trap) that was the basis for a cold atom source. This design gives the atoms a possibility to escape towards one particular direction. Then, we have extracted the atoms from this anisotropic trap in order to create a continuous beam of cold atoms. We have applied three methods of extraction. Firstly, the launching of atoms was performed by reducing the intensity of one of the cooling laser beams in the desired launching direction. Secondly, a frequency detuning between the two laser laser beams produced the launching of atoms by a so-called 'moving molasses'. The third method consisted in applying a static magnetic field that induced the launching of atoms in the direction of this magnetic field. At the same time, another research on cold atoms was initiated at the I.H.A. It consisted in cooling a large volume of atoms from a cell, using an isotropic light. This offers an interesting alternative to the traditional optical molasses. (author)

Time measurement - technical importance of most exact clocks

International Nuclear Information System (INIS)

Goebel, E.O.; Riehle, F.

2004-01-01

The exactness of the best atomic clocks currently shows a temporal variation of 1 second in 30 million years. This means that we have reached the point of the most exact frequency and time measurement ever. In the past, there was a trend towards increasing the exactness in an increasingly fast sequence. Will this trend continue? And who will profit from it? This article is meant to give answers to these questions. This is done by presenting first the level reached currently with the best atomic clocks and describing the research activities running worldwide with the aim of achieving even more exact clocks. In the second part, we present examples of various areas of technical subjects and research in which the most exact clocks are being applied presently and even more exact ones will be needed in the future [de

Fault-Tolerant Self-Stabilizing Distributed Clock Synchronization Protocol for Arbitrary Digraphs

Science.gov (United States)

Malekpour, Mahyar R. (Inventor)

2014-01-01

A self-stabilizing network in the form of an arbitrary, non-partitioned digraph includes K nodes having a synchronizer executing a protocol. K-1 monitors of each node may receive a Sync message transmitted from a directly connected node. When the Sync message is received, the logical clock value for the receiving node is set to between 0 and a communication latency value (gamma) if the clock value is less than a minimum event-response delay (D). A new Sync message is also transmitted to any directly connected nodes if the clock value is greater than or equal to both D and a graph threshold (T(sub S)). When the Sync message is not received the synchronizer increments the clock value if the clock value is less than a resynchronization period (P), and resets the clock value and transmits a new Sync message to all directly connected nodes when the clock value equals or exceeds P.

The Clock gene clone and its circadian rhythms in Pelteobagrus vachelli

Science.gov (United States)

Qin, Chuanjie; Shao, Ting

2015-05-01

The Clock gene, a key molecule in circadian systems, is widely distributed in the animal kingdom. We isolated a 936-bp partial cDNA sequence of the Clock gene ( Pva-clock) from the darkbarbel catfish Pelteobagrus vachelli that exhibited high identity with Clock genes of other species of fish and animals (65%-88%). The putative domains included a basic helix-loop-helix (bHLH) domain and two period-ARNT-single-minded (PAS) domains, which were also similar to those in other species of fish and animals. Pva-Clock was primarily expressed in the brain, and was detected in all of the peripheral tissues sampled. Additionally, the pattern of Pva-Clock expression over a 24-h period exhibited a circadian rhythm in the brain, liver and intestine, with the acrophase at zeitgeber time 21:35, 23:00, and 23:23, respectively. Our results provide insight into the function of the molecular Clock of P. vachelli.

Use of cesium-137 methodology in the evaluation of superficial erosive processes

International Nuclear Information System (INIS)

Andrello, Avacir Casanova; Appoloni, Carlos Roberto; Guimaraes, Maria de Fatima; Nascimento Filho, Virgilio Franco do

2003-01-01

Superficial erosion is one of the main soil degradation agents and erosion rates estimations for different edaphic climate conditions for the conventional models, as USLE and RUSLE, are expensive and time-consuming. The use of cesium- 137 anthropogenic radionuclide is a new methodology that has been much studied and its application in the erosion soil evaluation has grown in countries as USA, UK, Australia and others. A brief narration of this methodology is being presented, as the development of the equations utilized for the erosion rates quantification through the cesium- 137 measurements. Two watersheds studied in Brazil have shown that the cesium- 137 methodology was practicable and coherent with the survey in field for applications in erosion studies. (author)

Distribution of plutonium and cesium in alluvial soils of the Los Alamos environs

International Nuclear Information System (INIS)

Nyhan, J.W.; Miera, F.R. Jr.; Peters, R.J.

1976-01-01

The alluvial soils of three liquid waste disposal areas at Los Alamos were sampled to determine plutonium and cesium distributional relationships and correlations with soil physical-chemical properties. Radionuclide concentrations were determined for soil samples as a function of soil depth and distance from the waste outfall. The cesium-plutonium data were correlated with levels of organic carbon, carbonates, exchangeable and water-soluble cations, pH, cation exchange capacity, bulk density, surface area and geometric particle size of these soils. The distribution patterns of soil plutonium and cesium were also compared to the waste use history of the three study areas

Preparation of Modified Kaolin Filler with Cesium and Its Application in Security Paper

Directory of Open Access Journals (Sweden)

Houssni El-Saied

2013-01-01

Full Text Available In this study, cesium was added intentionally during paper manufacture for protecting the papers against forgery and counterfeiting by sorbing cesium ions (Cs+ on kaolin, used as special filler in papermaking. The sorption of cesium from aqueous solution by kaolin was studied as a function of pH, shaking time, cesium initial concentration, and mass of kaolin using batch technique. The results showed that a solution containing 10 mg/L Cs+ and 250 mg of kaolin at pH 6 can be used to modify the kaolin. Paper handsheets were prepared containing various percentages of the modified kaolin. The mechanical and optical properties of paper handsheets were studied. The prepared paper handsheets were irradiated by gamma irradiation using different doses. Fourier transform infrared (FTIR spectroscopy was used to study the effect of kaolin modification by cesium and gamma irradiation on paper handsheets properties. The results indicated that modified kaolin enhanced the mechanical and optical properties of paper handsheets. Electron spin resonance (ESR spectroscopy and laser-induced breakdown spectroscopy (LIBS were also used. They provided rapid, sensitive and nondestructive techniques in differentiating between different questioned documents. This study presents a new concept in manufacturing security papers and anticounterfeiting applications.

A Method for Estimating BeiDou Inter-frequency Satellite Clock Bias

Directory of Open Access Journals (Sweden)

LI Haojun

2016-02-01

Full Text Available A new method for estimating the BeiDou inter-frequency satellite clock bias is proposed, considering the shortage of the current methods. The constant and variable parts of the inter-frequency satellite clock bias are considered in the new method. The data from 10 observation stations are processed to validate the new method. The characterizations of the BeiDou inter-frequency satellite clock bias are also analyzed using the computed results. The results of the BeiDou inter-frequency satellite clock bias indicate that it is stable in the short term. The estimated BeiDou inter-frequency satellite clock bias results are molded. The model results show that the 10 parameters of model for each satellite can express the BeiDou inter-frequency satellite clock bias well and the accuracy reaches cm level. When the model parameters of the first day are used to compute the BeiDou inter-frequency satellite clock bias of the second day, the accuracy also reaches cm level. Based on the stability and modeling, a strategy for the BeiDou satellite clock service is presented to provide the reference of our BeiDou.

Intact interval timing in circadian CLOCK mutants.

Science.gov (United States)

Cordes, Sara; Gallistel, C R

2008-08-28

While progress has been made in determining the molecular basis for the circadian clock, the mechanism by which mammalian brains time intervals measured in seconds to minutes remains a mystery. An obvious question is whether the interval-timing mechanism shares molecular machinery with the circadian timing mechanism. In the current study, we trained circadian CLOCK +/- and -/- mutant male mice in a peak-interval procedure with 10 and 20-s criteria. The mutant mice were more active than their wild-type littermates, but there were no reliable deficits in the accuracy or precision of their timing as compared with wild-type littermates. This suggests that expression of the CLOCK protein is not necessary for normal interval timing.

Adsorption of iodine and cesium onto some cement materials

Energy Technology Data Exchange (ETDEWEB)

Mine, Tatsuya [Mitsui Shipbuilding and Engineering Co. Ltd., Tokyo (Japan); Mihara, Morihiro; Ito, Masaru [Power Reactor and Nuclear Fuel Development Corp., Tokai, Ibaraki (Japan). Tokai Works; Kato, Hiroshige [IDC, Tokai, Ibaraki (Japan)

1997-06-01

Cement materials, being expected to be used in structural materials in underground disposals of radioactive wastes, may adsorb nuclides resulting in retardation of their migration in environment. In this report adsorption behaviors of cement pastes toward iodine (as anion) and cesium (as cation) were studied. Adsorption of iodine was remarkable for OPC and MHP pastes that are known to have high molar ratio CaO/SiO{sub 2}, partition coefficient being 100 ml/g for initial tracer concentration of 10{sup -5} mol/l. Partition coefficient for cesium for PFA paste was found to be 5 ml/g on average. (S. Ohno)

Adsorption of iodine and cesium onto some cement materials

International Nuclear Information System (INIS)

Mine, Tatsuya; Mihara, Morihiro; Ito, Masaru

1997-06-01

Cement materials, being expected to be used in structural materials in underground disposals of radioactive wastes, may adsorb nuclides resulting in retardation of their migration in environment. In this report adsorption behaviors of cement pastes toward iodine (as anion) and cesium (as cation) were studied. Adsorption of iodine was remarkable for OPC and MHP pastes that are known to have high molar ratio CaO/SiO 2 , partition coefficient being 100 ml/g for initial tracer concentration of 10 -5 mol/l. Partition coefficient for cesium for PFA paste was found to be 5 ml/g on average. (S. Ohno)

A self-interfering clock as a "which path" witness.

Science.gov (United States)

Margalit, Yair; Zhou, Zhifan; Machluf, Shimon; Rohrlich, Daniel; Japha, Yonathan; Folman, Ron

2015-09-11

In Einstein's general theory of relativity, time depends locally on gravity; in standard quantum theory, time is global-all clocks "tick" uniformly. We demonstrate a new tool for investigating time in the overlap of these two theories: a self-interfering clock, comprising two atomic spin states. We prepare the clock in a spatial superposition of quantum wave packets, which evolve coherently along two paths into a stable interference pattern. If we make the clock wave packets "tick" at different rates, to simulate a gravitational time lag, the clock time along each path yields "which path" information, degrading the pattern's visibility. In contrast, in standard interferometry, time cannot yield "which path" information. This proof-of-principle experiment may have implications for the study of time and general relativity and their impact on fundamental effects such as decoherence and the emergence of a classical world. Copyright © 2015, American Association for the Advancement of Science.

Efficiency of Dry (Psidium guava) Leaves for The Removal of Cesium-137 from Aqueous Solutions

International Nuclear Information System (INIS)

Omar, H.A.; Abu-Kharda, S.A.; Abd El -Baset, L.A.; Abu-Shohba, R.M.

2012-01-01

Batch experiments for the removal of cesium-137 from aqueous solution onto guava leaves (psidium guava) and carbonized guava leaves were studied as a function of contact time, dosage, ph value and initial concentration ion. The sorption process was described by pseudo first-order, pseudo second-order, Morris and Elovich kinetic models. Cesium concentrations were ranged between 2x10 -5 - 1x10 -3 M. Sorption data have been interpreted in terms of Langmuir, Freundlich and Dubinin-Radushkevich isotherms. The maximum sorption capacity of carbonized guava leaves adsorbent for cesium removal was 8.02 mgg -1 . The results of the present study suggest that carbonized guava leaves can be used beneficially for cesium removal from aqueous solution.

Determining hyperfine transitions with electromagnetically induced transparency and optical pumping

International Nuclear Information System (INIS)

Lee Yi-Chi; Tsai Chin-Chun; Huang Chen-Han; Chui Hsiang-Chen; Chang Yung-Yung

2011-01-01

A system is designed to observe the phenomena of electromagnetically induced transparency and optical pumping in cesium D 1 and D 2 lines at room temperature. When a pump laser is frequency-locked on the top of a hyperfine transition and the frequency of the probe laser scans over another hyperfine transition, a spectrum of V-type electromagnetically induced transparency or an optical pumping can be observed depending on whether the two lasers share a common ground state. Therefore, these results can be used to identify the unknown hyperfine transitions of the D 1 line transitions. For educational purposes, this system is helpful for understanding the electromagnetically induced transparency and the optical pumping

Caustic-Side Solvent Extraction: Prediction of Cesium Extraction from Actual Wastes and Actual Waste Simulants

International Nuclear Information System (INIS)

Delmau, L.H.; Haverlock, T.J.; Sloop, F.V. Jr.; Moyer, B.A.

2003-01-01

This report presents the work that followed the CSSX model development completed in FY2002. The developed cesium and potassium extraction model was based on extraction data obtained from simple aqueous media. It was tested to ensure the validity of the prediction for the cesium extraction from actual waste. Compositions of the actual tank waste were obtained from the Savannah River Site personnel and were used to prepare defined simulants and to predict cesium distribution ratios using the model. It was therefore possible to compare the cesium distribution ratios obtained from the actual waste, the simulant, and the predicted values. It was determined that the predicted values agree with the measured values for the simulants. Predicted values also agreed, with three exceptions, with measured values for the tank wastes. Discrepancies were attributed in part to the uncertainty in the cation/anion balance in the actual waste composition, but likely more so to the uncertainty in the potassium concentration in the waste, given the demonstrated large competing effect of this metal on cesium extraction. It was demonstrated that the upper limit for the potassium concentration in the feed ought to not exceed 0.05 M in order to maintain suitable cesium distribution ratios

Byzantine-fault tolerant self-stabilizing protocol for distributed clock synchronization systems

Science.gov (United States)

Malekpour, Mahyar R. (Inventor)

2010-01-01

A rapid Byzantine self-stabilizing clock synchronization protocol that self-stabilizes from any state, tolerates bursts of transient failures, and deterministically converges within a linear convergence time with respect to the self-stabilization period. Upon self-stabilization, all good clocks proceed synchronously. The Byzantine self-stabilizing clock synchronization protocol does not rely on any assumptions about the initial state of the clocks. Furthermore, there is neither a central clock nor an externally generated pulse system. The protocol converges deterministically, is scalable, and self-stabilizes in a short amount of time. The convergence time is linear with respect to the self-stabilization period.

The role of the mechanical clock in medieval science.

Science.gov (United States)

Álvarez, Víctor Pérez

2015-03-01

The invention and spread of the mechanical clock is a complex and multifaceted historical phenomenon. Some of these facets, such as its social impact, have been widely studied, but their scientific dimensions have often been dismissed. The mechanical clock was probably born as a scientific instrument for driving a model of the universe, and not only natural philosophers but also kings, nobles and other members of the social elites showed an interest in clocks as scientific instruments. Public clocks later spread a new way of telling time based on equal hours, laying the foundations for changes in time consciousness that would accelerate scientific thinking. Copyright © 2015 Elsevier Ltd. All rights reserved.

Multiphoton ionization of atomic cesium

International Nuclear Information System (INIS)

Compton, R.N.; Klots, C.E.; Stockdale, J.A.D.; Cooper, C.D.

1984-01-01

We describe experimental studies of resonantly enhanced multi-photon ionization (MPI) of cesium atoms in the presence and absence of an external electric field. In the zero-field studies, photo-electron angular distributions for one- and two-photon resonantly enhanced MPI are compared with the theory of Tang and Lambropoulos. Deviations of experiment from theory are attributed to hyperfine coupling effects in the resonant intermediate state. The agreement between theory and experiment is excellent. In the absence of an external electric field, signal due to two-photon resonant three-photon ionization of cesium via np states is undetectable. Application of an electric field mixes nearby nd and ns levels, thereby inducing excitation and subsequent ionization. Signal due to two-photon excitation of ns levels in field-free experiments is weak due to their small photoionization cross section. An electric field mixes nearby np levels which again allows detectable photo-ionization signal. For both ns and np states the ''field induced'' MPI signal increases as the square of the electric field for a given principal quantum number and increases rapidly with n for a given field strength

The endogenous circadian clock programs animals to eat at certain times of the 24-hour day: What if we ignore the clock?

Science.gov (United States)

Jiang, Peng; Turek, Fred W

2018-04-16

The discovery of the molecular mechanisms underlying the circadian clock, which functions in virtually every cell throughout the body to coordinate biological processes to anticipate and better adapt to daily rhythmic changes in the environment, is one of the major biomedical breakthroughs in the 20th century. Twenty years after this breakthrough, the biomedical community is now at a new frontier to incorporate the circadian clock mechanisms into many areas of biomedical research, as studies continue to reveal an important role of the circadian clock in a wide range of biological functions and diseases. A forefront of this exciting area is the research of interactions between the clock and energy metabolism. In this review, we summarize animal and human studies linking disruptions of the circadian clock, either environmental or genetic, to metabolic dysfunctions associated with obesity, diabetes, and other metabolic disorders. We also discuss how these advances in circadian biology may pave the way to revolutionize clinical practice in the era of precision medicine. Copyright © 2018 Elsevier Inc. All rights reserved.

Strontium-90 and cesium-137 in freshwater (from September, 1982, to December, 1982)

International Nuclear Information System (INIS)

1982-01-01

Strontium-90 and cesium-137 in fresh water measured at 4 locations across Japan from September to December, 1982, are given in pCi/l, respectively. The methods of the collection and pretreatment of samples, the preparation of samples for analysis, the separation of strontium-90 and cesium-137, and the counting are also described. The sample was passed through a cation exchange column. Strontium and cesium were eluted with hydrochloric acid from the cation exchange column. The sample solution prepared was neutralized with sodium hydroxide. After sodium carbonate was added, the precipitate of strontium and calcium carbonates was separated. The supernatant solution was retained for cesium-137 determination. After the radiochemical separation, the mounted precipitate was counted for activity using a low background beta counter normally for 60 min. The radioactivity ranged 0.08 to 0.22 pCi/l for Sr-90 and 0.003 to 0.020 pCi/l for Cs-137 in the freshwater. (J.P.N.)

Metabolism of {sup 137}cesium, {sup 137}barium in the rat. Therapeutics of the contamination; Metabolisme du {sup 137}cesium, {sup 137}baryum chez le rat. Therapeutique de la contamination

Energy Technology Data Exchange (ETDEWEB)

Remy, J; Philippon, A; Lafuma, J; Walter, C [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires. Departement de la Protection Sanitaire, Laboratoire de Radiopathologie

1967-07-01

The authors carry out research into the distribution kinetics, the metabolism and the excretion of {sup 137}Cs - {sup 137}Ba in the rat. They show that these phenomena are independent of the method of applying a single dose. The distribution tends to adopt in all cases a typical shape which remains the same depending on the body burden. Biological analysis of the state of the cesium in the biological media shows that it is transported in the free and ionised form. Considering the problem of the method of penetration of the cesium ion in the intracellular medium, and in particular by the in vivo and in vitro kinetic study of the plasma - red cell system, the authors make the assumption that an active transport of cesium occurs by the cell membrane. They thus arrive at an overall picture of the cesium distribution in the organism which is essentially characterized by a dynamic distribution equilibrium between two compartments: 99 per cent of the cesium accumulates in the intracellular pool, 1 per cent in the extracellular liquids. This latter compartment is open to the emunctories. Because, of the active transport by the cell membranes, the intracellular pool is filled rapidly but discharge is slow. This phenomenon is the limiting factor in the decrease of the body burden. From this representation, the authors deduce the reasons for the relative failure of the various therapeutic methods examined up till now by themselves or by other authors. The stimulation of the natural emunctories in the case of diuretics for example, can only improve the purification of the extracellular compartment. Now this latter contains only 1 per cent of the body burden and recharging is slow. Furthermore the methods designed to counteract or inhibit the active transport of cesium by the cell membrane are still at the present time incompatible with the survival of the cell. (authors) [French] Les auteurs etudient experimentalement la cinetique de distribution, le metabolisme et l

Metabolism of {sup 137}cesium, {sup 137}barium in the rat. Therapeutics of the contamination; Metabolisme du {sup 137}cesium, {sup 137}baryum chez le rat. Therapeutique de la contamination

Energy Technology Data Exchange (ETDEWEB)

Remy, J.; Philippon, A.; Lafuma, J.; Walter, C. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires. Departement de la Protection Sanitaire, Laboratoire de Radiopathologie

1967-07-01

The authors carry out research into the distribution kinetics, the metabolism and the excretion of {sup 137}Cs - {sup 137}Ba in the rat. They show that these phenomena are independent of the method of applying a single dose. The distribution tends to adopt in all cases a typical shape which remains the same depending on the body burden. Biological analysis of the state of the cesium in the biological media shows that it is transported in the free and ionised form. Considering the problem of the method of penetration of the cesium ion in the intracellular medium, and in particular by the in vivo and in vitro kinetic study of the plasma - red cell system, the authors make the assumption that an active transport of cesium occurs by the cell membrane. They thus arrive at an overall picture of the cesium distribution in the organism which is essentially characterized by a dynamic distribution equilibrium between two compartments: 99 per cent of the cesium accumulates in the intracellular pool, 1 per cent in the extracellular liquids. This latter compartment is open to the emunctories. Because, of the active transport by the cell membranes, the intracellular pool is filled rapidly but discharge is slow. This phenomenon is the limiting factor in the decrease of the body burden. From this representation, the authors deduce the reasons for the relative failure of the various therapeutic methods examined up till now by themselves or by other authors. The stimulation of the natural emunctories in the case of diuretics for example, can only improve the purification of the extracellular compartment. Now this latter contains only 1 per cent of the body burden and recharging is slow. Furthermore the methods designed to counteract or inhibit the active transport of cesium by the cell membrane are still at the present time incompatible with the survival of the cell. (authors) [French] Les auteurs etudient experimentalement la cinetique de distribution, le metabolisme et l

The retinal clock in mammals: role in health and disease

Directory of Open Access Journals (Sweden)

Felder-Schmittbuhl MP

2017-05-01

Full Text Available Marie-Paule Felder-Schmittbuhl,1,* Hugo Calligaro,2 Ouria Dkhissi-Benyahya2,* 1Institute of Cellular and Integratives Neurosciences, UPR3212, CNRS, Université de Strasbourg, Strasbourg, 2University of Lyon, Stem Cell and Brain Research Institute, INSERM U1208, Bron, France *These authors contributed equally to this work Abstract: The mammalian retina contains an extraordinary diversity of cell types that are highly organized into precise circuits to perceive and process visual information in a dynamic manner and transmit it to the brain. Above this builds up another level of complex dynamic, orchestrated by a circadian clock located within the retina, which allows retinal physiology, and hence visual function, to adapt to daily changes in light intensity. The mammalian retina is a remarkable model of circadian clock because it harbors photoreception, self-sustained oscillator function, and physiological outputs within the same tissue. However, the location of the retinal clock in mammals has been a matter of long debate. Current data have shown that clock properties are widely distributed among retinal cells and that the retina is composed of a network of circadian clocks located within distinct cellular layers. Nevertheless, the identity of the major pacemaker, if any, still warrants identification. In addition, the retina coordinates rhythmic behavior by providing visual input to the master hypothalamic circadian clock in the suprachiasmatic nuclei (SCN. This light entrainment of the SCN to the light/dark cycle involves a network of retinal photoreceptor cells: rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs. Although it was considered that these photoreceptors synchronized both retinal and SCN clocks, new data challenge this view, suggesting that none of these photoreceptors is involved in photic entrainment of the retinal clock. Because circadian organization is a ubiquitous feature of the retina and controls

Expression conservation within the circadian clock of a monocot: natural variation at barley Ppd-H1 affects circadian expression of flowering time genes, but not clock orthologs.

Science.gov (United States)

Campoli, Chiara; Shtaya, Munqez; Davis, Seth J; von Korff, Maria

2012-06-21

The circadian clock is an endogenous mechanism that coordinates biological processes with daily changes in the environment. In plants, circadian rhythms contribute to both agricultural productivity and evolutionary fitness. In barley, the photoperiod response regulator and flowering-time gene Ppd-H1 is orthologous to the Arabidopsis core-clock gene PRR7. However, relatively little is known about the role of Ppd-H1 and other components of the circadian clock in temperate crop species. In this study, we identified barley clock orthologs and tested the effects of natural genetic variation at Ppd-H1 on diurnal and circadian expression of clock and output genes from the photoperiod-response pathway. Barley clock orthologs HvCCA1, HvGI, HvPRR1, HvPRR37 (Ppd-H1), HvPRR73, HvPRR59 and HvPRR95 showed a high level of sequence similarity and conservation of diurnal and circadian expression patterns, when compared to Arabidopsis. The natural mutation at Ppd-H1 did not affect diurnal or circadian cycling of barley clock genes. However, the Ppd-H1 mutant was found to be arrhythmic under free-running conditions for the photoperiod-response genes HvCO1, HvCO2, and the MADS-box transcription factor and vernalization responsive gene Vrn-H1. We suggest that the described eudicot clock is largely conserved in the monocot barley. However, genetic differentiation within gene families and differences in the function of Ppd-H1 suggest evolutionary modification in the angiosperm clock. Our data indicates that natural variation at Ppd-H1 does not affect the expression level of clock genes, but controls photoperiodic output genes. Circadian control of Vrn-H1 in barley suggests that this vernalization responsive gene is also controlled by the photoperiod-response pathway. Structural and functional characterization of the barley circadian clock will set the basis for future studies of the adaptive significance of the circadian clock in Triticeae species.

The Chip-Scale Atomic Clock - Recent Development Progress

Science.gov (United States)

2004-09-01

35th Annual Precise Time and Time Interval (PTTI) Meeting 467 THE CHIP-SCALE ATOMIC CLOCK – RECENT DEVELOPMENT PROGRESS R. Lutwak ...1] R. Lutwak , et al., 2003, “The Chip-Scale Atomic Clock – Coherent Population Trapping vs. Conventional Interrogation,” in

Therapeutic effects of cesium-137 radiation in head and neck malignancy

International Nuclear Information System (INIS)

Lee, J.W.

1978-01-01

In radiation therapy, many fundamental physical and biological facts and theories must be applied in order to establish a scientific level of practice. There is a voluminous amount of information pertaining to these matters. Cesium-137 is a radioactive nuclide available as a fission product from nuclear reactions. Cesium-137 emits gamma rays at 0.663 MeV. Its half life of about 30 years is an advantage over that of cobalt-60, but cesium-137 is lower, and the specific activity is much less. Author has clinically observed of 150 cases of cesium-137 therapy on head and neck malignancies from Jan. 1971 to Oct. 1978. The following results were observed: 1) Age distribution showed predilection in fifth and decades and sex ratio revealed higher in male than female about 4 times. 2) Laryngeal cancer (34%) maxillary cancer (20.7%) and tongue cancer (12%) occupied high incidence in classification of disease. 3) The cases of radiation only therapeutic group (5000-7000 rad) revealed 61 cases (41.2%) and pre and post operative radiation group (1000-3000 rad) revealed 36 cases (24.3%). 4) In combined therapy (60 cases) arterial infusion group revealed 29 cases and 10 cases of operative group, 11 cases of well prognostic group respectively. (author)

Immobilisation of radio cesium loaded ammonium molybdo phosphate in glass matrices

International Nuclear Information System (INIS)

Yalmali, Vrunda S.; Singh, I.J.; Sathi Sasidharan, N.; Deshingkar, D.S.

2004-11-01

Long half life and easy availability from high level wastes make 137 Cesium most economical radiation source. High level liquid waste processing for 137 Cesium removal has become easier due to development of Cesium specific granulated ammonium molybdophosphate (AMP) composite. In such applications, resulting spent composite AMP itself represents high active solid waste and immobilization of these materials in cement may not be acceptable. Studies on immobilization of 137 Cs loaded AMP were taken up in order to achieve twin goals of increasing safety and minimizing processing costs of the final matrix. Studies indicated that phosphate modified sodium borosilicate SPNM glasses prepared under usual oxidizing conditions are not suitable for immobilization of 137 Cs loaded on AMP .Phosphate glasses containing Na 2 O, P 2 O 5 , B 2 O 3 , Fe 2 O 3 , Al 2 O 3 and SiO 2 as major constituents are capable of incorporating 6 to 8 % AMP. The Normalized Leach rates of these glasses for sodium, cesium, boron and silica are 10 -4 to 10 -6 gm/cm 2 /day which are comparable to or better than those reported for NBS glasses incorporating HLW. Homogeneity of the final matrix was confirmed by x-ray diffraction analysis. Further studies on characterization of these glasses would establish their acceptability. (author)

Strontium-90 and cesium-137 in freshwater from May 1984

International Nuclear Information System (INIS)

1984-01-01

Strontium-90 and cesium-137 in freshwater measured in May 1984 are given in pCi/l. The sampling point is 1, Kasumigaura-Lake (Ibaraki). Collection and pretreatment of samples, preparation of samples for analysis, separation of strontium-90 and cesium-137, determination of stable strontium, calcium and potassium, and counting are described. The sample was passed through a cation exchange column. After the radiochemical separation, the mounted precipitates were counted for activity using low background beta counters normally for 60 minutes. (Mori, K.)

Clock synchronization and dispersion

International Nuclear Information System (INIS)

Giovannetti, Vittorio; Lloyd, Seth; Maccone, Lorenzo; Wong, Franco N C

2002-01-01

We present a method to defeat effects of dispersion of timing signals when synchronizing clocks. It is based on the recently proposed 'conveyor belt synchronization' scheme and on the quantum dispersion cancellation effect

Modeling approach to various time and spatial scale environmental issues in Fukushima. Related to radioactive cesium migration in aquatic systems

International Nuclear Information System (INIS)

Kurikami, Hiroshi; Kitamura, Akihiro; Yamada, Susumu; Machida, Masahiko

2015-01-01

Several numerical models have been prepared to deal with various time- and spatial-scale issues related to radioactive cesium migration in environment in Fukushima area. The SACT (Soil and Cesium Transport) model developed by the Japan Atomic Energy Agency (JAEA) predicts middle- to long-term evolution of radioactive cesium distribution due to soil erosion, subsequent sediment transport and deposition, and radioactive cesium migration based on the Universal Soil Loss Equation (USLE). The TODAM (Time-dependent One-dimensional Degradation and Migration) model, iRIC/Nays2D and the FLESCOT (Flow, Energy, Salinity, Sediment, Contaminant Transport) model are one-, two- and three-dimensional river/reservoir/coastal models, respectively. Based on conservation equations of sediment and radioactive cesium, they treat advection and diffusion of suspended sediment and cesium, deposition of sediment to bed, re-suspension from bed and adsorption/desorption of radioactive cesium. These models are suitable for small and short time scale issues such as high discharges of sediment and radioactive cesium from rivers due to heavy rainfall events. This paper describes fragments of the JAEA’s approaches of modeling to deal with the issues corresponding to radioactive cesium migration in environment with some case studies. (author)

Test procedures and instructions for single shell tank saltcake cesium removal with crystalline silicotitanate

Energy Technology Data Exchange (ETDEWEB)

Duncan, J.B.

1997-01-07

This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test, using Hanford Single Shell Tank Saltcake from tanks 24 t -BY- I 10, 24 1 -U- 108, 24 1 -U- 109, 24 1 -A- I 0 1, and 24 t - S-102, in a bench-scale column. The cesium sorbent to be tested is crystalline siticotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-024, Hanford Single Shell Tank Saltcake Cesium Removal Test Plan.

Legal Time of the Republic of Colombia and its international traceability using the Cesium Atomic Clock - Time and Frequency National Standard

Science.gov (United States)

Hernández Forero, Liz Catherine; Bahamón Cortés, Nelson

2017-06-01

Around the world, there are different providers of timestamp (mobile, radio or television operators, satellites of the GPS network, astronomical measurements, etc.), however, the source of the legal time for a country is either the national metrology institute or another designated laboratory. This activity requires a time standard based on an atomic time scale. The International Bureau of Weights and Measures (BIPM) calculates a weighted average of the time kept in more than 60 nations and produces a single international time scale, called Coordinated Universal Time (UTC). This article presents the current time scale that generates Legal Time for the Republic of Colombia produced by the Instituto Nacional de Metrología (INM) using the time and frequency national standard, a cesium atomic oscillator. It also illustrates how important it is for the academic, scientific and industrial communities, as well as the general public, to be synchronized with this time scale, which is traceable to the International System (SI) of units, through international comparisons that are made in real time.

Association between circadian clock genes and diapause incidence in Drosophila triauraria.

Directory of Open Access Journals (Sweden)

Hirokazu Yamada

Full Text Available Diapause is an adaptive response triggered by seasonal photoperiodicity to overcome unfavorable seasons. The photoperiodic clock is a system that controls seasonal physiological processes, but our knowledge about its physiological mechanisms and genetic architecture remains incomplete. The circadian clock is another system that controls daily rhythmic physiological phenomena. It has been argued that there is a connection between the two clocks. To examine the genetic connection between them, we analyzed the associations of five circadian clock genes (period, timeless, Clock, cycle and cryptochrome with the occurrence of diapause in Drosophila triauraria, which shows a robust reproductive diapause with clear photoperiodicity. Non-diapause strains found in low latitudes were compared in genetic crosses with the diapause strain, in which the diapause trait is clearly dominant. Single nucleotide polymorphism and deletion analyses of the five circadian clock genes in backcross progeny revealed that allelic differences in timeless and cryptochrome between the strains were additively associated with the differences in the incidence of diapause. This suggests that there is a molecular link between certain circadian clock genes and the occurrence of diapause.

Decorporation of mixture of strontium and cesium isotopes with domestic mineral waters

International Nuclear Information System (INIS)

Slavov, S.; Filev, G.; Kiradzhiev, G.

1990-01-01

The possibilities of Bulgarian mineral waters to decorporate mixtures of strontium and cesium radioisotopes, simultaneous entering the body, were studied. A modified effect in respect to radioactive strontium was found. Modification of the effect of mixing two diferent types of mineral waters was not proven. No effect was found of potassium-containing mineral water on radioactive cesium kinetics. 1 tab., 7 refs

MTL-Model Checking of One-Clock Parametric Timed Automata is Undecidable

Directory of Open Access Journals (Sweden)

Karin Quaas

2014-03-01

Full Text Available Parametric timed automata extend timed automata (Alur and Dill, 1991 in that they allow the specification of parametric bounds on the clock values. Since their introduction in 1993 by Alur, Henzinger, and Vardi, it is known that the emptiness problem for parametric timed automata with one clock is decidable, whereas it is undecidable if the automaton uses three or more parametric clocks. The problem is open for parametric timed automata with two parametric clocks. Metric temporal logic, MTL for short, is a widely used specification language for real-time systems. MTL-model checking of timed automata is decidable, no matter how many clocks are used in the timed automaton. In this paper, we prove that MTL-model checking for parametric timed automata is undecidable, even if the automaton uses only one clock and one parameter and is deterministic.

Application of radioisotope for radio-luminous watch and clock industry in Japan

International Nuclear Information System (INIS)

Murayama, Yoshihiko

1981-01-01

In 1979, Japan became No. 1 watch and clock production country in the world, and has produced 88 million watches and 59 million clocks in 1980. About 65% of them were exported. The production of radio-luminous watches and clocks in 1980 was estimated as 13 million and 11 million, respectively, and has increased by 40% as compared with the previous year. In Japan, the law concerning the prevention of radiation injuries due to radioisotopes and others is applied to radio-luminous watches and clocks, because radioactive substances are contained in luminous paint, and the production is regulated by the law as unsealed RI-using establishments. The permitted establishments engaging in radio-luminous watches and clocks are 3 luminous paint makers, 9 painting works and 35 watch and clock assembling plants. The RI utilized for radio-luminous watches and clocks is limited to Pm-147 at present, and 3788 Ci was used in 1980. About 70 years have elapsed since luminous paint was used for watches and clocks for the first time. The ISO instituted the international standard on radio-luminous paint for watches and clocks in 1975. The beta-ray emitted by Pm-147 is shielded perfectly by glasses and cases, and only the dose of brems-strahlung X-ray is the problem. The radiation control in radio-luminous watch and clock plants is described. (Kako, I.)

Decontamination of Radioactive Cesium Released from Fukushima Daiichi Nuclear Power Plant - 13277

Energy Technology Data Exchange (ETDEWEB)

Parajuli, Durga; Minami, Kimitaka; Tanaka, Hisashi; Kawamoto, Tohru [Nanosystem Research Institute, National Institute of Advanced Industrial Science and Technology - AIST (Japan)

2013-07-01

Peculiar binding of Cesium to the soil clay minerals remained the major obstacle for the immediate Cs-decontamination of soil and materials containing clay minerals like sludge. Experiments for the removal of Cesium from soil and ash samples from different materials were performed in the lab scale. For soil and sludge ash formed by the incineration of municipal sewage sludge, acid treatment at high temperature is effective while washing with water removed Cesium from ashes of plants or burnable garbage. Though total removal seems a difficult task, water-washing of wood-ash or garbage-ash at 40 deg. C removes >90% radiocesium, while >60% activity can be removed from soil and sludge-ash by acid washing at 95 deg. C. (authors)

Cesium injection system for negative ion duoplasmatrons

International Nuclear Information System (INIS)

Kobayashi, M.; Prelec, K.; Sluyters, T.J.

1978-01-01

A design for admitting cesium vapor into a hollow hydrogen plasma discharge in a duoplasmatron ion source for the purpose of increasing the negative hydrogen ion output current is described. 60 mA beam currents for negative hydrogen ions are reported

Protecting Clock Synchronization: Adversary Detection through Network Monitoring

Directory of Open Access Journals (Sweden)

Elena Lisova

2016-01-01

Full Text Available Nowadays, industrial networks are often used for safety-critical applications with real-time requirements. Such applications usually have a time-triggered nature with message scheduling as a core property. Scheduling requires nodes to share the same notion of time, that is, to be synchronized. Therefore, clock synchronization is a fundamental asset in real-time networks. However, since typical standards for clock synchronization, for example, IEEE 1588, do not provide the required level of security, it raises the question of clock synchronization protection. In this paper, we identify a way to break synchronization based on the IEEE 1588 standard, by conducting a man-in-the-middle (MIM attack followed by a delay attack. A MIM attack can be accomplished through, for example, Address Resolution Protocol (ARP poisoning. Using the AVISPA tool, we evaluate the potential to perform a delay attack using ARP poisoning and analyze its consequences showing both that the attack can, indeed, break clock synchronization and that some design choices, such as a relaxed synchronization condition mode, delay bounding, and using knowledge of environmental conditions, can make the network more robust/resilient against these kinds of attacks. Lastly, a Configuration Agent is proposed to monitor and detect anomalies introduced by an adversary performing attacks targeting clock synchronization.

Mining for novel candidate clock genes in the circadian regulatory network

OpenAIRE

Bhargava, Anuprabha; Herzel, Hanspeter; Ananthasubramaniam, Bharath

2015-01-01

Background Most physiological processes in mammals are temporally regulated by means of a master circadian clock in the brain and peripheral oscillators in most other tissues. A transcriptional-translation feedback network of clock genes produces near 24 h oscillations in clock gene and protein expression. Here, we aim to identify novel additions to the clock network using a meta-analysis of public chromatin immunoprecipitation sequencing (ChIP-seq), proteomics and protein-protein interaction...

Efficient electron injection from solution-processed cesium stearate interlayers in organic light-emitting diodes

NARCIS (Netherlands)

Wetzelaer, G. A. H.; Najafi, A.; Kist, R. J. P.; Kuik, M.; Blom, P. W. M.

2013-01-01

The electron-injection capability of solution-processed cesium stearate films in organic light-emitting diodes is investigated. Cesium stearate, which is expected to exhibit good solubility and film formation due to its long hydrocarbon chain, is synthesized using a straightforward procedure.

Clock Technology Development in the Laser Cooling and Atomic Physics (LCAP) Program

Science.gov (United States)

Seidel, Dave; Thompson, R. J.; Klipstein, W. M.; Kohel, J.; Maleki, L.

2000-01-01

This paper presents the Laser Cooling and Atomic Physics (LCAP) program. It focuses on clock technology development. The topics include: 1) Overview of LCAP Flight Projects; 2) Space Clock 101; 3) Physics with Clocks in microgravity; 4) Space Clock Challenges; 5) LCAP Timeline; 6) International Space Station (ISS) Science Platforms; 7) ISS Express Rack; 8) Space Qualification of Components; 9) Laser Configuration; 10) Clock Rate Comparisons: GPS Carrier Phase Frequency Transfer; and 11) ISS Model Views. This paper is presented in viewgraph form.

Clocking Scheme for Switched-Capacitor Circuits

DEFF Research Database (Denmark)

Steensgaard-Madsen, Jesper

1998-01-01

A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed.......A novel clocking scheme for switched-capacitor (SC) circuits is presented. It can enhance the understanding of SC circuits and the errors caused by MOSFET (MOS) switches. Charge errors, and techniques to make SC circuits less sensitive to them are discussed....

Detection of the actinides and cesium from environmental samples

Science.gov (United States)

Snow, Mathew Spencer

Detection of the actinides and cesium in the environment is important for a variety of applications ranging from environmental remediation to safeguards and nuclear forensics. The utilization of multiple different elemental concentrations and isotopic ratios together can significantly improve the ability to attribute contamination to a unique source term and/or generation process; however, the utilization of multiple elemental "signatures" together from environmental samples requires knowledge of the impact of chemical fractionation for various elements under a variety of environmental conditions (including predominantly aqueous versus arid conditions). The research reported in this dissertation focuses on three major areas: 1. Improving the understanding of actinide-mineral interactions at ultra-low concentrations. Chapter 2 reports a batch sorption and modeling study of Np(V) sorption to the mineral goethite from attomolar to micromolar concentrations. 2. Improving the detection capabilities for Thermal Ionization Mass Spectrometry (TIMS) analyses of ultra-trace cesium from environmental samples. Chapter 4 reports a new method which significantly improves the chemical yields, purification, sample processing time, and ultimately, the detection limits for TIMS analyses of femtogram quantities of cesium from a variety of environmental sample matrices. 3. Demonstrating how actinide and cesium concentrations and isotopic ratios from environmental samples can be utilized together to determine a wealth of information including environmental transport mechanisms (e.g. aqueous versus arid transport) and information on the processes which generated the original material. Chapters1, 3 and 5 demonstrate these principles using Pu, Am, Np, and Cs concentrations and isotopic ratios from contaminated soils taken near the Subsurface Disposal Area (SDA) of Idaho National Laboratory (INL) (a low level radioactive waste disposal site in southeastern Idaho).

British domestic synchronous clocks 1930-1980 the rise and fall of a technology

CERN Document Server

Pook, Leslie Philip

2015-01-01

This book complements available one-make books on domestic synchronous clocks. It is also a history of science book that sets British domestic synchronous clocks, their manufacturers and technology in their social context. Part I covers the historical background, British domestic synchronous clock manufacturers and brands, how synchronous clocks work, domestic synchronous clock cases, practical advice on the servicing of domestic synchronous clocks, and analysis of the marketing and reliability of British domestic synchronous clocks. This analysis provides an explanation of the rise and eventual fall of their technology. Part II contains galleries of a selection of British domestic synchronous clocks, and of the movements with which they are fitted. There is a front and back view of each clock, together with a brief description. Views of each movement include views with the movement partly dismantled, together with a brief technical description of the movement. This profusely illustrated book is primarily fo...

Preliminary Evaluation of Cesium Distribution for Wet Sieving Process Planned for Soil Decontamination in Japan - 13104

Energy Technology Data Exchange (ETDEWEB)

Enokida, Y.; Tanada, Y.; Hirabayashi, D. [Graduate School of Engineering, 1 Furo-cho Nagoya-shi, Aichi-ken, 4648603 (Japan); Sawada, K. [EcoTopia Science Institute, Nagoya University, 1 Furo-cho Nagoya-shi, Aichi-ken, 4648603 (Japan)

2013-07-01

For the purpose of decontaminating radioactive cesium from a huge amount of soil, which has been estimated to be 1.2x10{sup 8} m{sup 3} by excavating to a 5-cm depth from the surface of Fukushima Prefecture where a severe nuclear accident occurred at TEPCO's power generating site and has emitted a significant amount of radioactive materials, mainly radioactive cesium, a wet sieving process was selected as one of effective methods available in Japan. Some private companies have demonstrated this process for soil treatment in the Fukushima area by testing at their plants. The results were very promising, and a full-fledged application is expected to follow. In the present study, we spiked several aqueous samples containing soil collected from an industrial wet sieving plant located near our university for the recycling of construction wastes with non-radioactive cesium hydroxide. The present study provides scientific data concerning the effectiveness in volume reduction of the contaminated soil by a wet sieving process as well as the cesium distribution between the liquid phase and clay minerals for each sub-process of the full-scale one, but a simulating plant equipped with a process of coagulating sedimentation and operational safety fundamentals for the plant. Especially for the latter aspect, the study showed that clay minerals of submicron size strongly bind a high content of cesium, which was only slightly removed by coagulation with natural sedimentation (1 G) nor centrifugal sedimentation (3,700 G) and some of the cesium may be transferred to the effluent or recycled water. By applying ultracentrifugation (257,000 G), most of submicron clay minerals containing cesium was removed, and the cesium amount which might be transferred to the effluent or recycled water, could be reduced to less than 2.3 % of the original design by the addition of a cesium barrier consisting of ultracentrifugation or a hollow fiber membrane. (authors)

LFCM [liquid-fed eramic melter] emission and off-gas system performance for feed component cesium

International Nuclear Information System (INIS)

Goles, R.W.; Andersen, C.M.

1986-09-01

Except for volatile off-gas effluents, overall adequacy of the liquid-fed ceramic melter (LFCM) system depends most upon its effectiveness in dealing with cesium. However, the mechanism responsible for melter cesium losses has proved insensitive to many LFCM operating and processing conditions. As a result, variations in inleakage, plenum temperature, feeding rate and waste loading do not significantly influence melter cesium performance. Feed composition, specifically halogen content, is the only processing variable that has had a significant effect. Due to the submicron nature of LFCM-generated aerosols, melter disengagement design features are not expected to be particularly effective in reducing cesium emission rates. For the same reason, the cesium performance of conventional quench scrubbers is quite low, being dependent only upon the magnitude of melter entrainment losses. Although a deep bed washable filter has been effective in removing submicron aerosols from the process exhaust, high performance has only been achieved under dry operating conditions. The melter's idling state does not appear to place additional demands upon the off-gas treatment system

Measurement of cesium and mercury emissions from the vitrification of simulated high level radioactive waste

International Nuclear Information System (INIS)

Zamecnik, J.R.

1992-01-01

In the Defense Waste Processing Facility at the Savannah River Site, it is desired to measure non-radioactive cesium in the offgas system from the glass melter. From a pilot scale melter system, offgas particulate samples were taken on filter paper media and analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The ICP-MS method proved to be sufficiently sensitive to measure cesium quantities as low as 0.135 μg, with the sensitivity being limited by the background cesium present in the filter paper. This sensitivity allowed determination of cesium decontamination factors for four of the five major components of the offgas system. In addition, total particulate measurements were also made. Measurements of mercury decontamination factors were made on the same equipment; the results indicate that most of the mercury in the offgas system probably exists as elemental mercury and HgCl 2 , with some HgO and Hg 2 Cl 2 . The decontamination factors determined for cesium, total particulate, and mercury all compared favorably with the design values

A preliminary deposit model for lithium-cesium-tantalum (LCT) pegmatites

Science.gov (United States)

Bradley, Dwight; McCauley, Andrew

2013-01-01

This report is part of an effort by the U.S. Geological Survey to update existing mineral deposit models and to develop new ones. We emphasize practical aspects of pegmatite geology that might directly or indirectly help in exploration for lithium-cesium-tantalum (LCT) pegmatites, or for assessing regions for pegmatite-related mineral resource potential. These deposits are an important link in the world’s supply chain of rare and strategic elements, accounting for about one-third of world lithium production, most of the tantalum, and all of the cesium.

Knudsen cell--mass spectrometer studies of cesium--urania interactions

International Nuclear Information System (INIS)

Collins, J.L.; Osborne, M.F.; Malinauskas, A.P.; Lorenz, R.A.; Manning, S.R.

1976-06-01

Limited Knudsen cell--mass spectrometer studies were made of the partial pressures of cesium-containing species [assumed to be primarily Cs(g)] over Cs 2 CO 3 and over phase equilibria involving UO 2 and probable Cs-U-O compounds formed from mixtures that initially contained either Cs 2 CO 3 -UO 2 or CsOH-UO 2 . Although additional work is required to further define the equilibria involved, the data demonstrate unambiguously a significant reduction in cesium partial pressures due to probable Cs-U-O compound formation and indicate essentially identical behavior with either CsOH or Cs 2 CO 3 as the starting material with UO 2

Cesium accumulation in native trees from the Brazilian Cerrado

International Nuclear Information System (INIS)

Franca, E.J.D.; Miranda, M.V.F.E.S.; Santos, T.O.; Cantinha, R.S.; Fernandes, E.A.D.N.

2016-01-01

Even considered not essential for plants, cesium may cycle within forest ecosystems. Taking into account the lack of knowledge on the distribution of this chemical element in Brazilian ecosystems, this work encompasses the unexpected cesium accumulation in native plant leaves from Cerradao, a Brazilian hotspot of world biodiversity. Some trees were Cs accumulators, achieving mass fractions in leaves 700 times higher (up to 12.7 mg kg -1 ) when compared to other Brazilian native tree leaves from the Atlantic Forest. In fact, such trace element accumulation in leaves was not previously noticed for Brazilian ecosystems despite the intra- and inter-species variability observed in Cerrado tree leaves. (author)

A bunch clock for the Advanced Photon Source

International Nuclear Information System (INIS)

Lenkszus, F.R.; Laird, R.J.

1997-01-01

A bunch clock timing module has been developed for use by Advanced Photon Source beamlines. The module provides bunch pattern and timing information that can be used to trigger beamline data collection equipment. The module is fully integrated into the control system software (EPICS) which automatically loads it with the storage ring fill pattern at injection time. Fast timing outputs (1 ns FWHM) for each stored bunch are generated using the storage ring low-level rf and revolution clock as input references. Fiber-optic-based transmitters and receivers are used to transmit a 352-MHz low-level rf reference to distributed bunch clock modules. The bunch clock module is a single-width VME module and may be installed in a VME crate located near beamline instrumentation. A prototype has been in use on the SRI CAT beamline for over a year. The design and integration into the control system timing software along with measured performance results are presented

Relativistic theory for syntonization of clocks in the vicinity of the Earth

Science.gov (United States)

Wolf, Peter; Petit, G.

1995-01-01

A well known prediction of Einstein's general theory of relativity states that two ideal clocks that move with a relative velocity, and are submitted to different gravitational fields will, in general, be observed to run at different rates. Similarly the rate of a clock with respect to the coordinate time of some spacetime reference system is dependent on the velocity of the clock in that reference system and on the gravitational fields it is submitted to. For the syntonization of clocks and the realization of coordinate times (like TAI) this rate shift has to be taken into account at an accuracy level which should be below the frequency stability of the clocks in question, i.e. all terms that are larger than the instability of the clocks should be corrected for. We present a theory for the calculation of the relativistic rate shift for clocks in the vicinity of the Earth, including all terms larger than one part in 10(exp 18). This, together with previous work on clock synchronization (Petit & Wolf 1993, 1994), amounts to a complete relativistic theory for the realization of coordinate time scales at picosecond synchronization and 10(exp -18) syntonization accuracy, which should be sufficient to accommodate future developments in time transfer and clock technology.

A new stochastic model considering satellite clock interpolation errors in precise point positioning

Science.gov (United States)

Wang, Shengli; Yang, Fanlin; Gao, Wang; Yan, Lizi; Ge, Yulong

2018-03-01

Precise clock products are typically interpolated based on the sampling interval of the observational data when they are used for in precise point positioning. However, due to the occurrence of white noise in atomic clocks, a residual component of such noise will inevitable reside within the observations when clock errors are interpolated, and such noise will affect the resolution of the positioning results. In this paper, which is based on a twenty-one-week analysis of the atomic clock noise characteristics of numerous satellites, a new stochastic observation model that considers satellite clock interpolation errors is proposed. First, the systematic error of each satellite in the IGR clock product was extracted using a wavelet de-noising method to obtain the empirical characteristics of atomic clock noise within each clock product. Then, based on those empirical characteristics, a stochastic observation model was structured that considered the satellite clock interpolation errors. Subsequently, the IGR and IGS clock products at different time intervals were used for experimental validation. A verification using 179 stations worldwide from the IGS showed that, compared with the conventional model, the convergence times using the stochastic model proposed in this study were respectively shortened by 4.8% and 4.0% when the IGR and IGS 300-s-interval clock products were used and by 19.1% and 19.4% when the 900-s-interval clock products were used. Furthermore, the disturbances during the initial phase of the calculation were also effectively improved.

Master Clock and Time-Signal-Distribution System

Science.gov (United States)

Tjoelker, Robert; Calhoun, Malcolm; Kuhnle, Paul; Sydnor, Richard; Lauf, John

2007-01-01

A timing system comprising an electronic master clock and a subsystem for distributing time signals from the master clock to end users is undergoing development to satisfy anticipated timing requirements of NASA s Deep Space Network (DSN) for the next 20 to 30 years. This system has a modular, flexible, expandable architecture that is easier to operate and maintain than the present frequency and timing subsystem (FTS).

Next Generation Extractants for Cesium Separation from High-Level Waste: From Fundamental Concepts to Site Implementation

International Nuclear Information System (INIS)

Moyer, Bruce A.; Bazelaire, Eve; Bonnesen, Peter V.; Bryan, Jeffrey C.; Delmau, Latitia H.; Engle, Nancy L.; Gorbunova, Maryna G.; Keever, Tamara J.; Levitskaia, Tatiana G.; Sachleben, Richard A.; Tomkins, Bruce A.; Bartsch, Richard A.

2004-01-01

General project objectives. This project seeks a fundamental understanding and major improvement in cesium separation from high-level waste by cesium-selective calixcrown extractants. Systems of particular interest involve novel solvent-extraction systems containing specific members of the calix[4]arene-crown-6 family, alcohol solvating agents, and alkylamines. Questions being addressed pertain to cesium binding strength, extraction selectivity, cesium stripping, and extractant solubility. Enhanced properties in this regard will specifically benefit cleanup projects funded by the USDOE Office of Environmental Management to treat and dispose of high-level radioactive wastes currently stored in underground tanks at the Savannah River Site (SRS), the Hanford site, and the Idaho National Environmental and Engineering Laboratory.1 The most direct beneficiary will be the SRS Salt Processing Project, which has recently identified the Caustic-Side Solvent Extraction (CSSX) process employing a calixcrown as its preferred technology for cesium removal from SRS high level tank waste.2 This technology owes its development in part to fundamental results obtained in this program

Next Generation Extractants for Cesium Separation from High-Level Waste: From Fundamental Concepts to Site Implementation

International Nuclear Information System (INIS)

Moyer, Bruce A; Bazelaire, Eve; Bonnesen, Peter V.; Bryan, Jeffrey C.; Delmau, Laetitia H.; Engle, Nancy L.; Gorbunova, Maryna G.; Keever, Tamara J.; Levitskaia, Tatiana G.; Sachleben, Richard A.; Tomkins, Bruce A.; Bartsch, Richard A.; Talanov, Vladimir S.; Gibson, Harry W.; Jones, Jason W.; Hay, Benjamin P.

2003-01-01

This project seeks a fundamental understanding and major improvement in cesium separation from high-level waste by cesium-selective calixcrown extractants. Systems of particular interest involve novel solvent-extraction systems containing specific members of the calix[4]arene-crown-6 family, alcohol solvating agents, and alkylamines. Questions being addressed pertain to cesium binding strength, extraction selectivity, cesium stripping, and extractant solubility. Enhanced properties in this regard will specifically benefit cleanup projects funded by the USDOE Office of Environmental Management to treat and dispose of high-level radioactive wastes currently stored in underground tanks at the Savannah River Site (SRS), the Hanford site, and the Idaho National Environmental and Engineering Laboratory.1 The most direct beneficiary will be the SRS Salt Processing Project, which has recently identified the Caustic-Side Solvent Extraction (CSSX) process employing a calixcrown as its preferred technology for cesium removal from SRS high-level tank waste.2 This technology owes its development in part to fundamental results obtained in this program

Effect of Cesium and Xenon Seeding in Negative Hydrogen Ion Sources

International Nuclear Information System (INIS)

Bacal, M.; Brunteau, A.M.; Deniset, C.; Elizarov, L.I.; Sube, F.; Tontegode, A.Y.; Whealton, J.H.

1999-01-01

It is well known that cesium seeding in volume hydrogen negative ion sources leads to a large reduction of the extracted electron current and in some cases to the enhancement of the negative ion current. The cooling of the electrons due to the addition of this heavy impurity was proposed as a possible cause of the mentioned observations. In order to verify this assumption, the authors seeded the hydrogen plasma with xenon, which has an atomic weight almost equal to that of cesium. The plasma properties were studied in the extraction region of the negative ion source Camembert III using a cylindrical electrostatic probe while the negative ion relative density was studied using laser photodetachment. It is shown that the xenon mixing does not enhance the negative ion density and leads to the increase of the electron density, while the cesium seeding reduces the electron density

Reduction of cesium levels in the diet through management of food

International Nuclear Information System (INIS)

Gerzabek, M.H.

1990-01-01

Several processes influence the radionuclide concentration of food products during processing: dilution, losses, concentration. Boiling of leaf vegetables yields a decontamination effect of up to 80% in the case of radioiodine. Peeling of potato tubers results in a reduction of the cesium concentration of 30%. The cesium and strontium concentration of flour is a factor of two lower as compared to the corresponding cereal grain due to the milling process. Significant discrimination occurs during the milk processing. The skimmed milk is significantly richer in cesium, iodine and especially in strontium than the cream. It follows that butter is depleted in its radionuclide contents as compared to other milk produce. Strontium is concentrated in the casein. Pressurized cooking in combination with salting or a treatment with acetic acid results in an Cs-activity loss of beef, veal and lamb meat of 50 to 90%. (Author) 3 figs., 7 tabs., 13 refs

Cesium-137

International Nuclear Information System (INIS)

Ammerich, Marc; Frot, Patricia; Gambini, Denis-Jean; Gauron, Christine; Moureaux, Patrick; Herbelet, Gilbert; Lahaye, Thierry; Pihet, Pascal; Rannou, Alain

2014-06-01

This sheet belongs to a collection which relates to the use of radionuclides essentially in unsealed sources. Its goal is to gather on a single document the most relevant information as well as the best prevention practices to be implemented. These sheets are made for the persons in charge of radiation protection: users, radioprotection-skill persons, labor physicians. Each sheet treats of: 1 - the radio-physical and biological properties; 2 - the main uses; 3 - the dosimetric parameters; 4 - the measurement; 5 - the protection means; 6 - the areas delimitation and monitoring; 7 - the personnel classification, training and monitoring; 8 - the effluents and wastes; 9 - the authorization and declaration administrative procedures; 10 - the transport; and 11 - the right conduct to adopt in case of incident or accident. This sheet deals specifically with Cesium-137

Progress toward Brazilian cesium fountain second generation

Science.gov (United States)

Bueno, Caio; Rodriguez Salas, Andrés; Torres Müller, Stella; Bagnato, Vanderlei Salvador; Varela Magalhães, Daniel

2018-03-01

The operation of a Cesium fountain primary frequency standard is strongly influenced by the characteristics of two important subsystems. The first is a stable frequency reference and the second is the frequency-transfer system. A stable standard frequency reference is key factor for experiments that require high accuracy and precision. The frequency stability of this reference has a significant impact on the procedures for evaluating certain systematic biases in frequency standards. This paper presents the second generation of the Brazilian Cesium Fountain (Br-CsF) through the opto-mechanical assembly and vacuum chamber to trap atoms. We used a squared section glass profile to build the region where the atoms are trapped and colled by magneto-optical technique. The opto-mechanical system was reduced to increase stability and robustness. This newest Atomic Fountain is essential to contribute with time and frequency development in metrology systems.

Clock synchronization by remote detection of correlated photon pairs

Energy Technology Data Exchange (ETDEWEB)

Ho, Caleb; Lamas-Linares, AntIa; Kurtsiefer, Christian [Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 (Singapore)], E-mail: christian.kurtsiefer@gmail.com

2009-04-15

In this study, we present an algorithm to detect the time and frequency differences of independent clocks based on observation of time-correlated photon pairs. This enables remote coincidence identification in entanglement-based quantum key distribution schemes without dedicated coincidence hardware, pulsed sources with a timing structure or very stable reference clocks. We discuss the method for typical operating conditions and show that the requirement for reference clock accuracy can be relaxed by about five orders of magnitude in comparison with previous schemes.

System-wide power management control via clock distribution network

Science.gov (United States)

Coteus, Paul W.; Gara, Alan; Gooding, Thomas M.; Haring, Rudolf A.; Kopcsay, Gerard V.; Liebsch, Thomas A.; Reed, Don D.

2015-05-19

An apparatus, method and computer program product for automatically controlling power dissipation of a parallel computing system that includes a plurality of processors. A computing device issues a command to the parallel computing system. A clock pulse-width modulator encodes the command in a system clock signal to be distributed to the plurality of processors. The plurality of processors in the parallel computing system receive the system clock signal including the encoded command, and adjusts power dissipation according to the encoded command.

Diffusion of cesium in sodium-borosilicate glasses for nuclear waste immobilisation. Diffusie van cesium in natrium borosilicaat glazen voor het immobiliseren van radioaktief afval

Energy Technology Data Exchange (ETDEWEB)

Janssen, F.J.J.G.; Sengers, E.G.F. (Keuring van Electrotechnische Materialen NV, Arnhem (Netherlands)); Waal, H. de (TPD-TNO-Glass technology, Eindhoven (Netherlands))

1989-09-26

Diffusion of cesium in borosilicate glass for high-level radioactive waste is discussed. For this purpose model glasses with non-radioactive elements are being made, in accordance with the specifications of the reprocessing plants, from which concentration couples are composed. A concentration couple consists of two cylinders of borosilicate glass which contain different amounts of cesium. After heat treatment the couples are studied by means of the scanning electron microscopy and X-ray microanalysis. The model study will provide a basis for predictions of the containment achieved over a longer period of time. (author). 11 refs.; 2 figs.; 2 tabs.

Complementary approaches to understanding the plant circadian clock

Directory of Open Access Journals (Sweden)

Ozgur E. Akman

2010-02-01

Full Text Available Circadian clocks are oscillatory genetic networks that help organisms adapt to the 24-hour day/night cycle. The clock of the green alga Ostreococcus tauri is the simplest plant clock discovered so far. Its many advantages as an experimental system facilitate the testing of computational predictions. We present a model of the Ostreococcus clock in the stochastic process algebra Bio-PEPA and exploit its mapping to different analysis techniques, such as ordinary differential equations, stochastic simulation algorithms and model-checking. The small number of molecules reported for this system tests the limits of the continuous approximation underlying differential equations. We investigate the difference between continuous-deterministic and discrete-stochastic approaches. Stochastic simulation and model-checking allow us to formulate new hypotheses on the system behaviour, such as the presence of self-sustained oscillations in single cells under constant light conditions. We investigate how to model the timing of dawn and dusk in the context of model-checking, which we use to compute how the probability distributions of key biochemical species change over time. These show that the relative variation in expression level is smallest at the time of peak expression, making peak time an optimal experimental phase marker. Building on these analyses, we use approaches from evolutionary systems biology to investigate how changes in the rate of mRNA degradation impacts the phase of a key protein likely to affect fitness. We explore how robust this circadian clock is towards such potential mutational changes in its underlying biochemistry. Our work shows that multiple approaches lead to a more complete understanding of the clock.

Metabolism of 137cesium, 137barium in the rat. Therapeutics of the contamination

International Nuclear Information System (INIS)

Remy, J.; Philippon, A.; Lafuma, J.; Walter, C.

1967-01-01

The authors carry out research into the distribution kinetics, the metabolism and the excretion of 137 Cs - 137 Ba in the rat. They show that these phenomena are independent of the method of applying a single dose. The distribution tends to adopt in all cases a typical shape which remains the same depending on the body burden. Biological analysis of the state of the cesium in the biological media shows that it is transported in the free and ionised form. Considering the problem of the method of penetration of the cesium ion in the intracellular medium, and in particular by the in vivo and in vitro kinetic study of the plasma - red cell system, the authors make the assumption that an active transport of cesium occurs by the cell membrane. They thus arrive at an overall picture of the cesium distribution in the organism which is essentially characterized by a dynamic distribution equilibrium between two compartments: 99 per cent of the cesium accumulates in the intracellular pool, 1 per cent in the extracellular liquids. This latter compartment is open to the emunctories. Because, of the active transport by the cell membranes, the intracellular pool is filled rapidly but discharge is slow. This phenomenon is the limiting factor in the decrease of the body burden. From this representation, the authors deduce the reasons for the relative failure of the various therapeutic methods examined up till now by themselves or by other authors. The stimulation of the natural emunctories in the case of diuretics for example, can only improve the purification of the extracellular compartment. Now this latter contains only 1 per cent of the body burden and recharging is slow. Furthermore the methods designed to counteract or inhibit the active transport of cesium by the cell membrane are still at the present time incompatible with the survival of the cell. (authors) [fr

A simple electromagnetic model for the light clock of special relativity

International Nuclear Information System (INIS)

Smith, Glenn S

2011-01-01

Thought experiments involving a light clock are common in introductory treatments of special relativity, because they provide a simple way of demonstrating the non-intuitive phenomenon of time dilation. The properties of the ray or pulse of light that is continuously reflected between the parallel mirrors of the clock are often stated vaguely and sometimes involve implicitly other relativistic effects, such as aberration. While this approach is adequate for an introduction, it should be supplemented by a more accurate analysis of the light clock once the formulae for the Lorentz transformation and the transformation of the electromagnetic field have been developed. A simple yet accurate electromagnetic model for the light clock is presented for this purpose. In this model, the ray of light in the qualitative treatment is replaced by a guided wave in a parallel-plate waveguide. Expressions for the electromagnetic field and energy density within the waveguide are determined in the inertial frame in which the clock is at rest and the laboratory frame in which the clock is moving with constant velocity. The analytical expressions and graphical results obtained clearly demonstrate the operation of the clock and time dilation, as well as other interesting relativistic effects.

Physical barrier effect of geopolymeric waste form on diffusivity of cesium and strontium.

Science.gov (United States)

Jang, J G; Park, S M; Lee, H K

2016-11-15

The present study investigates the physical barrier effect of geopolymeric waste form on leaching behavior of cesium and strontium. Fly ash-based geopolymers and slag-blended geopolymers were used as solidification agents. The leaching behavior of cesium and strontium from geopolymers was evaluated in accordance with ANSI/ANS-16.1. The diffusivity of cesium and strontium in a fly ash-based geopolymer was lower than that in Portland cement by a factor of 10(3) and 10(4), respectively, showing significantly improved immobilization performance. The leaching resistance of fly ash-based geopolymer was relatively constant regardless of the type of fly ash. The diffusivity of water-soluble cesium and strontium ions were highly correlated with the critical pore diameter of the binder. The critical pore diameter of the fly ash-based geopolymer was remarkably smaller than those of Portland cement and slag-blended geopolymer; consequently, its ability physically to retard the diffusion of nuclides (physical barrier effect) was superior. Copyright © 2016 Elsevier B.V. All rights reserved.

Conductivity of cesium-seeded atmospheric pressure plasmas near thermal equilibrium

Energy Technology Data Exchange (ETDEWEB)

Harris, L. P.

1963-04-15

Measurements were made of the electric conductivities of gaseous mixtures formed by the addition of small fractions of cesium vapor to nitrogen, helium, neon, or argon. The mixtures studied were maintained near thermal equilibrium at temperatures in the 1500 to 2000 deg K range and a total pressure of 1 atm. The cesium vapor pressures ranged over two decades, from 0.1 to 10 torr. The apparatus consists, in essence, of two heated zones connected by a slow flow. The first zone is a low-temperature (200 to 400 deg C) oven where the body-gas flow picks up the cesium vapor. The second zone is a small electrically heated furnace (1250 to 1850 deg C) containing a diode test section. The principal measurements taken were the seeding temperature, furnace temperature, and voltages and currents in the test section. The results exhibit variations with temperature, seeding pressure, and gas species that correlate reasonably well with simple theory and values for electron collision frequencies and cross sections taken from the literature. (auth)

Fabrication of stimuli-sensitive hydrogel for the removal of cesium

Energy Technology Data Exchange (ETDEWEB)

Yang, Hee-Man; Bong, Sang Bum; Park, Chan Woo; Lee, Kune Woo; Seo, Bum-Kyoung; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-05-15

The nuclear accident at the Fukushima Daiichi nuclear power station in 2011 released a huge quantity of radioactive contaminants into the environment.1 Among these, cesium Cs-137 is the most problematic contaminant due to its long half-life (30.2 years), and high-energy gamma ray (γ-ray) emissions. 2 Various surface including road, roof, house, building were contaminated with Cs-137. These coating materials have some problems and limitation such as toxic component, and lack of reusability of materials related to the cost. Thus, a more cost-effective and environmental friendly coating materials is still desired. 3 In the present study, the stimuli-sensitive hydrogel were fabricated for the removal of radioactive Cs from solid surface. We describe the morphology, structure, and physical property of these stimuli sensitive hydrogel. In addition, their ability to eliminate cesium was also evaluated. The smart hydrogel coating materials showed an excellent morphology change from the liquid to film by addition of Ca ion. Therefore, the stimuli-sensitive hydrogel demonstrated good potential for the treatment of contaminated surface for the removal of radioactive cesium.

Fabrication of stimuli-sensitive hydrogel for the removal of cesium

International Nuclear Information System (INIS)

Yang, Hee-Man; Bong, Sang Bum; Park, Chan Woo; Lee, Kune Woo; Seo, Bum-Kyoung; Moon, Jei Kwon

2015-01-01

The nuclear accident at the Fukushima Daiichi nuclear power station in 2011 released a huge quantity of radioactive contaminants into the environment.1 Among these, cesium Cs-137 is the most problematic contaminant due to its long half-life (30.2 years), and high-energy gamma ray (γ-ray) emissions. 2 Various surface including road, roof, house, building were contaminated with Cs-137. These coating materials have some problems and limitation such as toxic component, and lack of reusability of materials related to the cost. Thus, a more cost-effective and environmental friendly coating materials is still desired. 3 In the present study, the stimuli-sensitive hydrogel were fabricated for the removal of radioactive Cs from solid surface. We describe the morphology, structure, and physical property of these stimuli sensitive hydrogel. In addition, their ability to eliminate cesium was also evaluated. The smart hydrogel coating materials showed an excellent morphology change from the liquid to film by addition of Ca ion. Therefore, the stimuli-sensitive hydrogel demonstrated good potential for the treatment of contaminated surface for the removal of radioactive cesium