WorldWideScience

Sample records for atomic clouds

  1. Coherent Forward Broadening in Cold Atom Clouds

    CERN Document Server

    Sutherland, R T

    2015-01-01

    It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Further, it is demonstrated how the strong directionality of the coherent interactions causes the cloud's spectra to depend strongly on its shape, even when the cloud is held at constant densities. These two numerical observations can be predicted analytically by extending the single photon wave-function model. Lastly, elongating a cloud along the line of laser propagation causes the excitation probability distribution to deviate from the exponential decay predicted by the Beer-Lambert law to the extent where the atoms in the back of the cloud are more excited than the atoms in the front. These calculations are conducted at low densities relevant to recent experiments.

  2. Coherent forward broadening in cold atom clouds

    Science.gov (United States)

    Sutherland, R. T.; Robicheaux, F.

    2016-02-01

    It is shown that homogeneous line-broadening in a diffuse cold atom cloud is proportional to the resonant optical depth of the cloud. Furthermore, it is demonstrated how the strong directionality of the coherent interactions causes the cloud's spectra to depend strongly on its shape, even when the cloud is held at constant densities. These two numerical observations can be predicted analytically by extending the single-photon wave-function model. Lastly, elongating a cloud along the line of laser propagation causes the excitation probability distribution to deviate from the exponential decay predicted by the Beer-Lambert law to the extent where the atoms at the back of the cloud are more excited than the atoms at the front. These calculations are conducted at the low densities relevant to recent experiments.

  3. Doppler cooling of an optically dense cloud of trapped atoms

    CERN Document Server

    Schmidt, P O; Werner, J; Binhammer, T; Görlitz, A; Pfau, T; Schmidt, Piet O.; Hensler, Sven; Binhammer, Thomas; G\\"{o}rlitz, Axel; Pfau, Tilman

    2002-01-01

    We have studied a general technique for laser cooling a cloud of polarized trapped atoms down to the Doppler temperature. A one-dimensional optical molasses using polarized light cools the axial motional degree of freedom of the atoms in the trap. Cooling of the radial degrees of freedom can be modelled by reabsorption of scattered photons in the optically dense cloud. We present experimental results for a cloud of chromium atoms in a magnetic trap. A simple model based on rate equations shows quantitative agreement with the experimental results. This scheme allows us to readily prepare a dense cloud of atoms in a magnetic trap with ideal starting conditions for evaporative cooling.

  4. Single structured light beam as an atomic cloud splitter

    International Nuclear Information System (INIS)

    We propose a scheme to split a cloud of cold noninteracting neutral atoms based on their dipole interaction with a single structured light beam which exhibits parabolic cylindrical symmetry. Using semiclassical numerical simulations, we establish a direct relationship between the general properties of the light beam and the relevant geometric and kinematic properties acquired by the atomic cloud as it passes through the beam.

  5. Preparation of Ultracold Atom Clouds at the Shot Noise Level

    Science.gov (United States)

    Gajdacz, M.; Hilliard, A. J.; Kristensen, M. A.; Pedersen, P. L.; Klempt, C.; Arlt, J. J.; Sherson, J. F.

    2016-08-01

    We prepare number stabilized ultracold atom clouds through the real-time analysis of nondestructive images and the application of feedback. In our experiments, the atom number N ˜1 06 is determined by high precision Faraday imaging with uncertainty Δ N below the shot noise level, i.e., Δ N Based on this measurement, feedback is applied to reduce the atom number to a user-defined target, whereupon a second imaging series probes the number stabilized cloud. By this method, we show that the atom number in ultracold clouds can be prepared below the shot noise level.

  6. Preparation of Ultracold Atom Clouds at the Shot Noise Level.

    Science.gov (United States)

    Gajdacz, M; Hilliard, A J; Kristensen, M A; Pedersen, P L; Klempt, C; Arlt, J J; Sherson, J F

    2016-08-12

    We prepare number stabilized ultracold atom clouds through the real-time analysis of nondestructive images and the application of feedback. In our experiments, the atom number N∼10^{6} is determined by high precision Faraday imaging with uncertainty ΔN below the shot noise level, i.e., ΔNatom number to a user-defined target, whereupon a second imaging series probes the number stabilized cloud. By this method, we show that the atom number in ultracold clouds can be prepared below the shot noise level. PMID:27563964

  7. Preparation of ultracold atom clouds at the shot noise level

    CERN Document Server

    Gajdacz, Miroslav; Kristensen, Mick A; Pedersen, Poul L; Klempt, Carsten; Arlt, Jan J; Sherson, Jacob F

    2016-01-01

    We prepare number stabilized ultracold clouds through the real-time analysis of non-destructive images and the application of feedback. In our experiments, the atom number ${N\\sim10^6}$ is determined by high precision Faraday imaging with uncertainty $\\Delta N$ below the shot noise level, i.e., $\\Delta N <\\sqrt{N}$. Based on this measurement, feedback is applied to reduce the atom number to a user-defined target, whereupon a second imaging series probes the number stabilized cloud. By this method, we show that the atom number in ultracold clouds can be prepared below the shot noise level.

  8. Experiments with a laser cooled cloud of atoms

    OpenAIRE

    Natarajan, Vasant; Banerjee, Ayan; Rapol, Umakant

    1999-01-01

    We discuss two experiments that can be performed using a cloud of laser-cooled and trapped atoms, namely Bose-Einstein condensation (BEC) and search for a permanent Electric Dipole Moment (EDM). BEC can be observed in Rb atoms in a magnetic trap by using forced evaporative cooling to continuously lower the temperature below the condensation limit. The cloud is cooled by preferentially ejecting the hottest atoms from a magnetic trap. The magnetic trap is loaded with laser-cooled atoms from a m...

  9. Sub-atom shot noise Faraday imaging of ultracold atom clouds

    CERN Document Server

    Kristensen, Mick A; Pedersen, Poul L; Klempt, Carsten; Sherson, Jacob F; Arlt, Jan J; Hilliard, Andrew J

    2016-01-01

    We demonstrate that a dispersive imaging technique based on the Faraday effect can measure the atom number in a large, ultracold atom cloud with a precision below the atom shot noise level. The minimally destructive character of the technique allows us to take multiple images of the same cloud, which enables sub-atom shot noise measurement precision of the atom number and allows for an in situ determination of the measurement precision. We have developed a noise model that quantitatively describes the noise contributions due to photon shot noise in the detected light and the noise associated with single atom loss. This model contains no free parameters and is calculated through an analysis of the fluctuations in the acquired images. For clouds containing $N \\sim 5 \\times 10^6$ atoms, we achieve a precision more than a factor of two below the atom shot noise level.

  10. Single shot three-dimensional imaging of dilute atomic clouds

    CERN Document Server

    Sakmann, Kaspar

    2014-01-01

    Light field microscopy methods together with three dimensional (3D) deconvolution can be used to obtain single shot 3D images of atomic clouds. We demonstrate the method using a test setup which extracts three dimensional images from a fluorescent $^{87}$Rb atomic vapor.

  11. From the warm magnetized atomic medium to molecular clouds

    CERN Document Server

    Hennebelle, P; Vázquez-Semadeni, E; Klessen, R; Audit, E

    2008-01-01

    {It has recently been proposed that giant molecular complexes form at the sites where streams of diffuse warm atomic gas collide at transonic velocities.} {We study the global statistics of molecular clouds formed by large scale colliding flows of warm neutral atomic interstellar gas under ideal MHD conditions. The flows deliver material as well as kinetic energy and trigger thermal instability leading eventually to gravitational collapse.} {We perform adaptive mesh refinement MHD simulations which, for the first time in this context, treat self-consistently cooling and self-gravity.} {The clouds formed in the simulations develop a highly inhomogeneous density and temperature structure, with cold dense filaments and clumps condensing from converging flows of warm atomic gas. In the clouds, the column density probability density distribution (PDF) peaks at $\\sim 2 \\times 10^{21} \\psc$ and decays rapidly at higher values; the magnetic intensity correlates weakly with density from $n \\sim 0.1$ to $10^4 \\pcc$, an...

  12. Correlation of spiral arm molecular clouds with cold atomic hydrogen

    International Nuclear Information System (INIS)

    The relationship between molecular clouds and the cold atomic hydrogen gas seen in self-absorption has been examined in the longitude range 36-40 deg. The results confirm what the authors found previously in another region of the Galaxy. By reanalyzing both sets of data, the authors show that those cold clouds which are detected both in H I self-absorption at 21 cm against a hotter background and in CO emission at 2.6 mm are confined to the Sagittarius spiral arm feature in velocity-longitude space. Outside of this arm feature, clouds which show both H I absorption and CO emission are very rare. 14 references

  13. Propagation of light through small clouds of cold interacting atoms

    OpenAIRE

    Jennewein, S; Sortais, Y. R. P.; Greffet, J. -J.; Browaeys, A.

    2015-01-01

    We demonstrate experimentally that a cloud of cold atoms with a size comparable to the wavelength of light can induce large group delays on a laser pulse when the laser is tightly focused on it and is close to an atomic resonance. Delays as large as -10 ns are observed, corresponding to "superluminal" propagation with negative group velocities as low as -300 m/s. Strikingly, this large delay is associated with a moderate extinction owing to the very small size of the cloud and to the light-in...

  14. Noise spectroscopy with large clouds of cold atoms

    CERN Document Server

    Kashanian, Samir Vartabi; Guerin, William; Lintz, Michel; Fouché, Mathilde; Kaiser, Robin

    2016-01-01

    Noise measurement is a powerful tool to investigate many phenomena from laser characterization to quantum behavior of light. In this paper, we report on intensity noise measurements obtained when a laser beam is transmitted through a large cloud of cold atoms. While this measurement could possibly investigate complex processes such as the influence of atomic motion, one is first limited by the conversion of the intrinsic laser frequency noise to intensity noise via the atomic resonance. We show that a simple model, based on a mean-field approach, which corresponds to describing the atomic cloud by a dielectric susceptibility, is sufficient to understand the main features of this conversion observed in the experimental intensity noise spectrum.

  15. Neutral atomic carbon in dense molecular clouds

    Science.gov (United States)

    Zmuidzinas, J.; Betz, A. L.; Boreiko, R. T.; Goldhaber, D. M.

    1988-01-01

    The 370 micron 3P2-3P1 fine-structure line of neutral carbon was detected in seven sources: OMC 1, NGC 2024, S140, W3, DR 21, M17, and W51. Simultaneous analysis of J = 2-1 data and available observations of the J = 1-0 line make it possible to deduce optical depths and excitation temperatures for these lines. These data indicate that both C I lines are likely to be optically thin, and that the ratio of C I to CO column densities in these clouds is typically about 0.1.

  16. Dynamic splitting and merging of an atom cloud on an atom chip

    Institute of Scientific and Technical Information of China (English)

    Ke Min; Yan Bo; Cheng Feng; Wang Yu-Zhu

    2009-01-01

    Chip-based atom interferometers bring together the advantages of atom chips and Bose-Einstein condensates. Their central prerequisite is that a condensate can be coherently split into two halves with a determined relative phase. This paper demonstrates the dynamical splitting and merging of an atom cloud with two U-wires on an atom chip. Symmetrical and asymmetrical splittings are realized by applying a bias field with different directions and magnitudes. The trajectories of the splitting are consistent with theoretical calculations. The atom chip is a good candidate for constructing an atom interferometer.

  17. Slow diffusion of light in a cold atomic cloud

    International Nuclear Information System (INIS)

    We study the diffusive propagation of multiply scattered light in an optically thick cloud of cold rubidium atoms illuminated by a quasiresonant laser beam. In the vicinity of a sharp atomic resonance, the energy transport velocity of the scattered light is almost 5 orders of magnitude smaller than the vacuum speed of light, reducing strongly the diffusion constant. We verify the theoretical prediction of a frequency-independent transport time around the resonance. We also observe the effect of the residual velocity of the atoms at long times

  18. Propagation of light through small clouds of cold interacting atoms

    CERN Document Server

    Jennewein, S; Greffet, J -J; Browaeys, A

    2015-01-01

    We demonstrate experimentally that a cloud of cold atoms with a size comparable to the wavelength of light can induce large group delays on a laser pulse when the laser is tightly focused on it and is close to an atomic resonance. Delays as large as -10 ns are observed, corresponding to "superluminal" propagation with negative group velocities as low as -300 m/s. Strikingly, this large delay is associated with a moderate extinction owing to the very small size of the cloud and to the light-induced interactions between atoms. It implies that a large phase shift is imprinted on the continuous laser beam, and opens interesting perspectives for applications to quantum technologies.

  19. Cooperative scattering and radiation pressure force in dense atomic clouds

    International Nuclear Information System (INIS)

    Atomic clouds prepared in ''timed Dicke'' states, i.e. states where the phase of the oscillating atomic dipole moments linearly varies along one direction of space, are efficient sources of superradiant light emission [Scully et al., Phys. Rev. Lett. 96, 010501 (2006)]. Here, we show that, in contrast to previous assertions, timed Dicke states are not the states automatically generated by incident laser light. In reality, the atoms act back on the driving field because of the finite refraction of the cloud. This leads to nonuniform phase shifts, which, at higher optical densities, dramatically alter the cooperative scattering properties, as we show by explicit calculation of macroscopic observables, such as the radiation pressure force.

  20. Spin diffusion in trapped clouds of strongly interacting cold atoms

    OpenAIRE

    Bruun, G. M.; Pethick, C.J.

    2011-01-01

    We show that puzzling recent experimental results on spin diffusion in a strongly interacting atomic gas may be understood in terms of the predicted spin diffusion coefficient for a generic strongly interacting system. Three important features play a central role: a) Fick's law for diffusion must be modified to allow for the trapping potential, b) the diffusion coefficient is inhomogeneous, due to the density variations in the cloud and c) the diffusion approximation fails in the outer parts ...

  1. The atomic hydrogen cloud in the saturnian system

    Science.gov (United States)

    Tseng, W.-L.; Johnson, R. E.; Ip, W.-H.

    2013-09-01

    The importance of Titan's H torus shaped by solar radiation pressure and of hydrogen atoms flowing out of Saturn's atmosphere in forming the broad hydrogen cloud in Saturn's magnetosphere is still debated. Since the Saturnian system also contains a water product torus which originates from the Enceladus plumes, the icy ring particles, and the inner icy satellites, as well as Titan's H2 torus, we have carried out a global investigation of the atomic hydrogen cloud taking into account all sources. We show that the velocity and angle distributions of the hot H ejected from Saturn's atmosphere following electron-impact dissociation of H2 are modified by collisions with the ambient atmospheric H2 and H. This in turn affects the morphology of the escaping hydrogen from Saturn, as does the morphology of the ionospheric electron distribution. Although an exact agreement with the Cassini observations is not obtained, our simulations show that H directly escaping from Titan is the dominant contributor in the outer magnetosphere. Of the total number of H observed by Cassini from 1 to 5RS, ∼5.7×1034, our simulations suggest ∼20% is from dissociation in the Enceladus torus, ∼5-10% is from dissociation of H2 in the atmosphere of the main rings, and ∼50% is from Titan's H torus, implying that ∼20% comes from Saturn atmosphere.

  2. Dicke subradiance in a large cloud of cold atoms

    CERN Document Server

    Guerin, William; Kaiser, Robin

    2015-01-01

    More than 60 years ago, Dicke published a seminal paper on coherence in spontaneous radiation process by a collection of atoms. Superradiance has since attracted a lot of interest, from its first experimental observation in a fully inverted system in the 1970s to single photon superradiance in the 2000s. Subradiance, on the contrary, has remained elusive, mainly because subradiant states are weakly coupled to the environment and are very sensitive to non radiative decoherence processes. They are thus much harder to populate and to observe. Avoiding decoherence effects by using a dilute cloud of laser-cooled atoms containing a large number of atoms, we report on direct observation of subradiance. In our experiment, we use a far detuned laser to avoid multiple scattering and detect the temporal decay after a sudden switch-off of the laser beam. After the fast decay of most of the fluorescence, we observe a very slow decay, with time constants as long as 100 times the natural lifetime of the excited state of ind...

  3. Fluid description of the cooperative scattering of light by spherical atomic clouds

    CERN Document Server

    Piovella, N; Courteille, Ph W

    2013-01-01

    When a cold atomic gas is illuminated by a quasi-resonant laser beam, light-induced dipole-dipole correlations make the scattering of light a cooperative process. Once a fluid description is adopted for the atoms, many scattering properties are captured by the definition of a complex refractive index. The solution of the scattering problem is here presented for spherical atomic clouds of arbitrary density profiles, such as parabolic densities characteristic of ultra-cold clouds. A new solution for clouds with infinite boundaries is derived, that is particularly useful for the Gaussian densities of thermal atomic clouds. The presence of Mie resonances, a signature of the cloud acting as a cavity for the light, is discussed. These resonances leave their fingerprint in various observables such as the scattered intensity or in the radiation pressure force, and can be observed by tuning the frequency of the incident laser field or the atom number.

  4. Collective resonance fluorescence in small and dense atom clouds: Comparison between theory and experiment

    CERN Document Server

    Jenkins, S D; Javanainen, J; Jennewein, S; Bourgain, R; Pellegrino, J; Sortais, Y R P; Browaeys, A

    2016-01-01

    We study the emergence of a collective optical response of a cold and dense $^{87}$Rb atomic cloud to a near-resonant low-intensity light when the atom number is gradually increased. Experimental observations are compared with microscopic stochastic simulations of recurrent scattering processes between the atoms that incorporate the atomic multilevel structure and the optical measurement setup. We analyze the optical response of an inhomogeneously-broadened gas and find that the experimental observations of the resonance line shifts and the total collected scattered light intensity in cold atom clouds substantially deviate from those of thermal atomic ensembles, indicating strong light-induced resonant dipole-dipole interactions between the atoms. At high densities, the simulations also predict a significantly slower decay of light-induced excitations in cold than in thermal atom clouds. The role of dipole-dipole interactions is discussed in terms of resonant coupling examples and the collective radiative exc...

  5. Observation of cooperative Mie scattering from an ultracold atomic cloud

    CERN Document Server

    Bender, H; Slama, S; Kaiser, R; Piovella, N; Zimmermann, C; Courteille, Ph W

    2010-01-01

    Scattering of light at a distribution of scatterers is an intrinsically cooperative process, which means that the scattering rate and the angular distribution of the scattered light are essentially governed by bulk properties of the distribution, such as its size, shape, and density, although local disorder and density fluctuations may have an important impact on the cooperativity. Via measurements of the radiation pressure exerted by a far-detuned laser beam on a very small and dense cloud of ultracold atoms, we are able to identify the respective roles of superradiant acceleration of the scattering rate and of Mie scattering in the cooperative process. They lead respectively to a suppression or an enhancement of the radiation pressure. We observe a maximum in the radiation pressure as a function of the induced phase shift, marking the borderline of the validity of the Rayleigh-Debye-Gans approximation from a regime, where Mie scattering is more complex. Our observations thus help to clarify the intricate re...

  6. Optimization of transfer of laser-cooled atom cloud to a quadrupole magnetic

    Indian Academy of Sciences (India)

    S P Ram; S K Tiwari; S R Mishra; H S Rawat

    2014-02-01

    We present here our experimental results on transfer of laser-cooled atom cloud to a quadrupole magnetic trap. We show that by choosing appropriately the ratio of potential energy in magnetic trap to kinetic energy of cloud in molasses, we can obtain the maximum phase-space density in the magnetic trap. These results guide us to choose the value of current to be switched in the quadrupole coils used for magnetic trapping for a given temperature of the cloud after molasses. This study is also useful to set the initial phase-space density of the cloud before evaporative cooling.

  7. Coherent Scattering of Near-Resonant Light by a Dense Microscopic Cold Atomic Cloud

    Science.gov (United States)

    Jennewein, S.; Besbes, M.; Schilder, N. J.; Jenkins, S. D.; Sauvan, C.; Ruostekoski, J.; Greffet, J.-J.; Sortais, Y. R. P.; Browaeys, A.

    2016-06-01

    We measure the coherent scattering of light by a cloud of laser-cooled atoms with a size comparable to the wavelength of light. By interfering a laser beam tuned near an atomic resonance with the field scattered by the atoms, we observe a resonance with a redshift, a broadening, and a saturation of the extinction for increasing atom numbers. We attribute these features to enhanced light-induced dipole-dipole interactions in a cold, dense atomic ensemble that result in a failure of standard predictions such as the "cooperative Lamb shift". The description of the atomic cloud by a mean-field model based on the Lorentz-Lorenz formula that ignores scattering events where light is scattered recurrently by the same atom and by a microscopic discrete dipole model that incorporates these effects lead to progressively closer agreement with the observations, despite remaining differences.

  8. An optically resolvable Schroedinger's cat from Rydberg dressed cold atom clouds

    International Nuclear Information System (INIS)

    In Rydberg dressed ultra-cold gases, ground state atoms inherit properties of a weakly admixed Rydberg state, such as sensitivity to long-range interactions. We show that through hyperfine-state dependent interactions, a pair of atom clouds can evolve into a spin and subsequently into a spatial Schroedinger's cat state: The pair, containing 40 atoms in total, is in a coherent superposition of two configurations, with cloud locations separated by micrometers. The mesoscopic nature of the superposition state can be proven with absorption imaging, while the coherence can be revealed though recombination and interference of the split wave packets.

  9. Cooperative fluorescence from a strongly driven dilute cloud of atoms

    DEFF Research Database (Denmark)

    Ott, Johan Raunkjær; Wubs, Martijn; Lodahl, Peter;

    2013-01-01

    We investigate cooperative fluorescence in a dilute cloud of strongly driven two-level emitters. Starting from the Heisenberg equations of motion, we compute the first-order scattering corrections to the saturation of the excited-state population and to the resonance-fluorescence spectrum, which...... both require going beyond the state-of-the-art linear-optics approach to describe collective phenomena. A dipole blockade is observed due to long-range dipole-dipole coupling that vanishes at stronger driving fields. Furthermore, we compute the inelastic component of the light scattered by a cloud of...

  10. Scale Factor Measurements for a Gyroscope Based on an Expanding Cloud of Atoms

    Science.gov (United States)

    Hoth, Gregory; Pelle, Bruno; Riedl, Stefan; Kitching, John; Donley, Elizabeth

    2016-05-01

    We present an atom interferometer that can simultaneously measure two-axis rotations and one-axis accelerations with a single cloud of atoms in an active evacuated volume of about 1 cm3. This is accomplished by extending the point-source interferometry technique (Dickerson et al. PRL, 111, 083001, 2013) to a compact regime. In this technique, the cloud of atoms is imaged after the interferometer sequence. Rotations cause spatial fringes to appear across the cloud. To realize a gyroscope with this method, it is necessary to know how the wave-vector of the spatial fringes, k, is related to the rotation rate, Ω. If the cloud is initially infinitesimally small, it can be shown that k = FΩ with a scale factor F determined by the time between interferometer pulses, the total free expansion time, and the wavelength of the interrogating laser. However, the point-source approximation is not appropriate in our case because the final size of the cloud in our experiment is between 1.4 and 5 times its initial size. We show experimentally that in this finite expansion regime the phase gradient is still well described by k = FΩ , but the scale factor F depends on the initial distribution of the atoms. We also present modeling that explains this dependence.

  11. Cooperative Fluorescence from a Strongly Driven Dilute Cloud of Atoms

    OpenAIRE

    Ott, Johan Raunkjær; Wubs, Martijn; Lodahl, Peter; Mortensen, N. Asger; Kaiser, R.

    2013-01-01

    We investigate cooperative fluorescence in a dilute cloud of strongly driven two-level emitters. Starting from the Heisenberg equations of motion, we compute the first-order scattering corrections to the saturation of the excited-state population and to the resonance-fluorescence spectrum, which both require going beyond the state-of-the-art linear-optics approach to describe collective phenomena. A dipole blockade is observed due to long-range dipole-dipole coupling that vanishes at stronger...

  12. The Image of the Atomic Bomb's Mushroom Cloud in Picture Books for Children

    OpenAIRE

    Gary Crew

    2012-01-01

    In The Alphabet Versus the Goddess: The Conflict Between Word and Image (1998), Leonard Shlain contends that the dissemination of the mushroom cloud image following the detonation of the atomic bomb over Hiroshima saved humankind from collective death by serving as a warning to of a future Armageddon. The image of the mushroom cloud is now over 50 years old and may well have lost its power to serve as a deterrent to the future use of the atomic bomb. Given that the children of today could con...

  13. Chaotic dynamics of dilute thermal atom clouds on stationary optical Bessel beams

    International Nuclear Information System (INIS)

    We characterize the semiclassical dynamics of dilute thermal atom clouds located in three-dimensional optical lattices generated by stationary optical Bessel beams. The dynamics of the cold atoms is explored in the quasi-Hamiltonian regime that arises using laser beams with far-off resonance detuning. Although the transverse structure of Bessel beams exhibits a complex topological structure, it is found that the longitudinal motion along the main propagation axis of the beam is the detonator of a high sensitivity of the atoms' motion to the initial conditions. This effect would not be properly described by bidimensional models. We show that an experimental implementation can be highly simplified by an analysis of the behaviour of the dynamical system under scale transformations. Experimentally feasible signatures of the chaotic dynamics of the atom clouds are also identified. (paper)

  14. Subradiance in a Large Cloud of Cold Atoms

    Science.gov (United States)

    Guerin, William; Araújo, Michelle O.; Kaiser, Robin

    2016-02-01

    Since Dicke's seminal paper on coherence in spontaneous radiation by atomic ensembles, superradiance has been extensively studied. Subradiance, on the contrary, has remained elusive, mainly because subradiant states are weakly coupled to the environment and are very sensitive to nonradiative decoherence processes. Here, we report the experimental observation of subradiance in an extended and dilute cold-atom sample containing a large number of particles. We use a far detuned laser to avoid multiple scattering and observe the temporal decay after a sudden switch-off of the laser beam. After the fast decay of most of the fluorescence, we detect a very slow decay, with time constants as long as 100 times the natural lifetime of the excited state of individual atoms. This subradiant time constant scales linearly with the cooperativity parameter, corresponding to the on-resonance optical depth of the sample, and is independent of the laser detuning, as expected from a coupled-dipole model.

  15. Fast compression of a cold atomic cloud using a blue detuned crossed dipole trap

    CERN Document Server

    Bienaime, Tom; de Lepinay, Laure Mercier; Bellando, Louis; Chabe, Julien; Kaiser, Robin

    2012-01-01

    We present the experimental realization of a compressible blue detuned crossed dipole trap for cold atoms allowing for fast dynamical compression (~ 5 - 10 ms) of 5x10^7 Rubidium atoms up to densities of ~ 10^13 cm^-3. The dipole trap consists of two intersecting tubes of blue-detuned laser light. These tubes are formed using a single, rapidly rotating laser beam which, for sufficiently fast rotation frequencies, can be accurately described by a quasi-static potential. The atomic cloud is compressed by dynamically reducing the trap volume leading to densities close to the Ioffe-Reggel criterion for light localization.

  16. Compression and localization of an atomic cloud in a time dependent optical lattice

    CERN Document Server

    Williams, W; Williams, Will

    2006-01-01

    We analyze a method to compress a cloud of cold atoms in a far off resonance optical lattice by dynamically changing the lattice parameters while cooling the atoms with optical molasses. Particle motion in the time dependent lattice is studied numerically using a three dimensional semiclassical model. We show that smoothly varying the lattice spacing from a large to a small value results in compression of more than 75% of the atoms initially in a Gaussian distributed cloud with standard deviation of 50 $\\mu$m into a single site of a two-dimensional lattice. The lattice site has an area of $A=0.76 \\lambda^2$ with $\\lambda$ the wavelength of the trapping beam. We demonstrate that an increase in the optical depth by a factor of at least 175 is possible.

  17. Superradiance in a Large and Dilute Cloud of Cold Atoms in the Linear-Optics Regime

    Science.gov (United States)

    Araújo, Michelle O.; Krešić, Ivor; Kaiser, Robin; Guerin, William

    2016-08-01

    Superradiance has been extensively studied in the 1970s and 1980s in the regime of superfluorescence, where a large number of atoms are initially excited. Cooperative scattering in the linear-optics regime, or "single-photon superradiance," has been investigated much more recently, and superradiant decay has also been predicted, even for a spherical sample of large extent and low density, where the distance between atoms is much larger than the wavelength. Here, we demonstrate this effect experimentally by directly measuring the decay rate of the off-axis fluorescence of a large and dilute cloud of cold rubidium atoms after the sudden switch off of a low-intensity laser driving the atomic transition. We show that, at large detuning, the decay rate increases with the on-resonance optical depth. In contrast to forward scattering, the superradiant decay of off-axis fluorescence is suppressed near resonance due to attenuation and multiple-scattering effects.

  18. Reduction of interference fringes in absorption imaging of cold atom cloud using eigenface method

    Institute of Scientific and Technical Information of China (English)

    Xiaolin Li; Min Ke; Bo Yan; Yuzhu Wang

    2007-01-01

    Eigenface method used in face recognition is introduced to reduce the pattern of interference fringes appearing in the absorption image of cold rubidium atom cloud trapped by an atom chip. The standard method for processing the absorption image is proposed, and the origin of the interference fringes is analyzed. Compared with the standard processing method which uses only one reference image, we take advantage of fifty reference images and reconstruct a new reference image which is more similar to the absorption image than all of the fifty original reference images. Then obvious reduction of interference fringes can be obtained.

  19. Superradiance in a Large Cloud of Cold Atoms in the Linear-Optics Regime

    CERN Document Server

    Araújo, Michelle O; Kaiser, Robin; Guerin, William

    2016-01-01

    Superradiance has been extensively studied in the 1970s and 1980s in the regime of superfluores-cence, where a large number of atoms are initially excited. Cooperative scattering in the linear-optics regime, or " single-photon superradiance ", has been investigated much more recently, and superra-diant decay has also been predicted, even for a spherical sample of large extent and low density. Here, we demonstrate this effect experimentally by directly measuring the decay rate of the off-axis fluorescence of a large and dilute cloud of cold atoms after the sudden switch-off of a low-intensity laser driving the atomic transition. We show that, at large detuning, the decay rate increases with the on-resonance optical depth. In contrast to forward scattering, the superradiant decay of off-axis fluorescence is suppressed near resonance due to attenuation and multiple-scattering effects.

  20. A summary of transition probabilities for atomic absorption lines formed in low-density clouds

    Science.gov (United States)

    Morton, D. C.; Smith, W. H.

    1973-01-01

    A table of wavelengths, statistical weights, and excitation energies is given for 944 atomic spectral lines in 221 multiplets whose lower energy levels lie below 0.275 eV. Oscillator strengths were adopted for 635 lines in 155 multiplets from the available experimental and theoretical determinations. Radiation damping constants also were derived for most of these lines. This table contains the lines most likely to be observed in absorption in interstellar clouds, circumstellar shells, and the clouds in the direction of quasars where neither the particle density nor the radiation density is high enough to populate the higher levels. All ions of all elements from hydrogen to zinc are included which have resonance lines longward of 912 A, although a number of weaker lines of neutrals and first ions have been omitted.

  1. Experimental limits on the velocities of sodium atoms sputtered from solid surfaces by hydrogen ions. [Na cloud production around Io

    Science.gov (United States)

    Stoner, J. O., Jr.

    1976-01-01

    Optical emission at 589.0 nm by sodium atoms sputtered from solid targets by hydrogen molecular ions was observed, and no accompanying broadening or shifts of this line could be detected relative to that from a laboratory lamp. This allowed an upper limit of about 500,000 cm/sec on the mean speed of ejected sodium atoms to be calculated. The results are consistent with the hypothesis that the atomic sodium cloud surrounding Io is produced by this mechanism.

  2. Mapping atomic and diffuse interstellar band absorption across the Magellanic Clouds and the Milky Way

    CERN Document Server

    Bailey, Mandy; Sarre, Peter J; Beckman, John E

    2015-01-01

    Diffuse interstellar bands (DIBs) trace warm neutral and weakly-ionized diffuse interstellar medium (ISM). Here we present a dedicated, high signal-to-noise spectroscopic study of two of the strongest DIBs, at 5780 and 5797 \\AA, in optical spectra of 666 early-type stars in the Small and Large Magellanic Clouds, along with measurements of the atomic Na\\,{\\sc i}\\,D and Ca\\,{\\sc ii}\\,K lines. The resulting maps show for the first time the distribution of DIB carriers across large swathes of galaxies, as well as the foreground Milky Way ISM. We confirm the association of the 5797 \\AA\\ DIB with neutral gas, and the 5780 \\AA\\ DIB with more translucent gas, generally tracing the star-forming regions within the Magellanic Clouds. Likewise, the Na\\,{\\sc i}\\,D line traces the denser ISM whereas the Ca\\,{\\sc ii}\\,K line traces the more diffuse, warmer gas. The Ca\\,{\\sc ii}\\,K line has an additional component at $\\sim200$--220 km s$^{-1}$ seen towards both Magellanic Clouds; this may be associated with a pan-Magellanic ...

  3. Demonstration of fold and cusp catastrophes in an atomic cloud reflected from an optical barrier in the presence of gravity

    CERN Document Server

    Rosenblum, Serge; Shomroni, Itay; Kaner, Roy; Arusi-Parpar, Talya; Raz, Oren; Dayan, Barak

    2013-01-01

    We experimentally demonstrate first-order (fold) and second-order (cusp) catastrophes in the density of an atomic cloud reflected from an optical barrier in the presence of gravity, and show their corresponding universal asymptotic behavior. The cusp point enables robust, field-free refocusing of an expanding atomic cloud with a wide velocity distribution. Specifically, the density attained at the cusp point in our experiment reached 65% of the peak density of the atoms in the trap prior to their release. We thereby add caustics to the various phenomena with parallels in optics that can be harnessed for manipulation of cold atoms. The structural stability of catastrophes provides inherent robustness against variations in the system's dynamics and initial conditions, making them suitable for manipulation of atoms under imperfect conditions and limited controllability.

  4. A new protein binding pocket similarity measure based on comparison of 3D atom clouds: application to ligand prediction

    OpenAIRE

    Hoffmann, Brice; Zaslavskiy, Mikhail; Vert, Jean-Philippe; Stoven, Véronique

    2009-01-01

    Motivation: Prediction of ligands for proteins of known 3D structure is important to understand structure-function relationship, predict molecular function, or design new drugs.\\\\ Results: We explore a new approach for ligand prediction in which binding pockets are represented by atom clouds. Each target pocket is compared to an ensemble of pockets of known ligands. Pockets are aligned in 3D space with further use of convolution kernels between clouds of points. Performance of the new method ...

  5. The coupling of rapidly synergistic cloud point extraction with thermospray flame furnace atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Rapidly synergistic cloud point extraction (RS-CPE) was coupled with thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) to result in new CPE patterns and accelerated (1 min) protocols. It is demonstrated, for the case of copper (II) ion, that TS-FF-AAS improves the sampling efficiency and the sensitivity of FAAS determinations. Problems of nebulization associated with previous methods based on the coupling of FAAS and RS-CPE are overcome. TS-FF-AAS also improves sensitivity and gives a limit of detection for copper of 0.20 μg L-1, which is better by a factor of 32. Compared to direct FAAS, the factor is 114. (author)

  6. Pion cloud contribution to the s-wave repulsion in pionic atoms

    International Nuclear Information System (INIS)

    The nuclear pion cloud contribution to the pion self-energy for pionic atoms is evaluated and one finds large cancellations between terms involving the ππ amplitude and other terms originating from the chiral lagrangian partners. While the individual terms depend strongly on the off-shell extrapolation of the ππ amplitude, the sum is model independent within the Olson and Turner family of chiral lagrangians keeping ξ+4η constant, as previously found for the πN →ππN and pion double-charge exchange in nuclei, and vanishes in the limit of mπ→0. One finds a small net repulsion which is however too small to account for the ''missing'' s-wave repulsion. A revision of the present status of the problem of the ''missing'' s-wave repulsion is done at the end. ((orig.))

  7. Determination of cadmium in real water samples by flame atomic absorption spectrometry after cloud point extraction

    International Nuclear Information System (INIS)

    Water pollution is a global threat and it is the leading world wide cause of death and diseases. The awareness of the potential danger posed by heavy metals to the ecosystems and in particular to human health has grown tremendously in the past decades. Separation and preconcentration procedures are considered of great importance in analytical and environmental chemistry. Cloud point is one of the most reliable and sophisticated separation methods for determination of traces quantities of heavy metals. Cloud point methodology was successfully employed for preconcentration of trace quantities of cadmium prior to their determination by flame atomic absorption spectrometry (FAAS). The metals react with 8-hydroxquinoline in a surfactant Triton X-114 medium. The following parameters such as pH, concentration of the reagent and Triton X-114, equilibrating temperature and centrifuging time were evaluated and optimized to enhance the sensitivity and extraction efficiency of the proposed method. Dilution of the surfactant-rich phase with acidified ethanol was performed after phase separation and the cadmium content was measured by FAAS. The validation of the procedure was carried out by spiking addition methods. The method was applied for determination of Cd in water samples of different ecosystems (lake and river). (author)

  8. Temperature and phase-space density of a cold atom cloud in a quadrupole magnetic trap

    Energy Technology Data Exchange (ETDEWEB)

    Ram, S. P.; Mishra, S. R.; Tiwari, S. K.; Rawat, H. S. [Raja Ramanna Centre for Advanced Technology, Indore (India)

    2014-08-15

    We present studies on modifications in the temperature, number density and phase-space density when a laser-cooled atom cloud from optical molasses is trapped in a quadrupole magnetic trap. Theoretically, for a given temperature and size of the cloud from the molasses, the phase-space density in the magnetic trap is shown first to increase with increasing magnetic field gradient and then to decrease with it after attaining a maximum value at an optimum value of the magnetic-field gradient. The experimentally-measured variation in the phase-space density in the magnetic trap with changing magnetic field gradient is shown to exhibit a similar trend. However, the experimentally-measured values of the number density and the phase-space density are much lower than the theoretically-predicted values. This is attributed to the experimentally-observed temperature in the magnetic trap being higher than the theoretically-predicted temperature. Nevertheless, these studies can be useful for setting a higher phase-space density in the trap by establishing an optimal value of the field gradient for a quadrupole magnetic trap.

  9. Temperature and phase-space density of cold atom cloud in a quadrupole magnetic trap

    CERN Document Server

    Ram, S P; Tiwari, S K; Rawat, H S

    2014-01-01

    We present studies on the modifications in temperature, number density and phase-space density when a laser cooled atom cloud from the optical molasses is trapped in a quadrupole magnetic trap. Theoretically it is shown that for a given temperature and size of the cloud from the molasses, the phase-space density in the magnetic trap first increases with magnetic field gradient and then decreases with it, after attaining a maximum value at an optimum value of magnetic field gradient. The experimentally measured variation in phase-space density in the magnetic trap with the magnetic field gradient has shown the similar trend. However, the experimentally measured values of number density and phase-space density are much lower than their theoretically predicted values. This is attributed to the higher experimentally observed temperature in the magnetic trap than the theoretically predicted temperature. Nevertheless, these studies can be useful to set a higher phase-space density in the trap by setting the optimum...

  10. Temperature and phase-space density of a cold atom cloud in a quadrupole magnetic trap

    International Nuclear Information System (INIS)

    We present studies on modifications in the temperature, number density and phase-space density when a laser-cooled atom cloud from optical molasses is trapped in a quadrupole magnetic trap. Theoretically, for a given temperature and size of the cloud from the molasses, the phase-space density in the magnetic trap is shown first to increase with increasing magnetic field gradient and then to decrease with it after attaining a maximum value at an optimum value of the magnetic-field gradient. The experimentally-measured variation in the phase-space density in the magnetic trap with changing magnetic field gradient is shown to exhibit a similar trend. However, the experimentally-measured values of the number density and the phase-space density are much lower than the theoretically-predicted values. This is attributed to the experimentally-observed temperature in the magnetic trap being higher than the theoretically-predicted temperature. Nevertheless, these studies can be useful for setting a higher phase-space density in the trap by establishing an optimal value of the field gradient for a quadrupole magnetic trap.

  11. Modelling the impact of noctilucent cloud formation on atomic oxygen and other minor constituents of the summer mesosphere

    Directory of Open Access Journals (Sweden)

    B. J. Murray

    2005-01-01

    Full Text Available The formation, evolution and eventual sublimation of noctilucent clouds (NLC may have a significant effect on the odd oxygen and hydrogen chemistry of the high latitude summer mesosphere. Three mechanisms are considered here: the direct uptake of atomic oxygen on the surface of the ice particles; the redistribution of water vapour, which changes the photochemical source of odd hydrogen species; and the direct photolysis of the ice particles themselves to produce odd hydrogen species in the gas phase. A 1-D photochemical model is employed to investigate the potential importance of these mechanisms. This shows, using the recently measured uptake coefficients of O on ice, that the heterogeneous removal of O on the surface of the cloud particles is too slow by at least a factor of 5x103 to compete with gas-phase O chemistry. The second and third mechanisms involve the solar Lyman-α photolysis of H2O in the gas and solid phase, respectively. During twilight, Lyman-α radiation is severely attenuated and these mechanisms are insignificant. In contrast, when the upper mesosphere is fully illuminated there is a dramatic impact on the O profile, with depletion of O at the base of the cloud layer of close to an order of magnitude. A correspondingly large depletion in O3 is also predicted, while H, OH, HO2 and H2O2 are found to be enhanced by factors of 3-5. In fact, rocket-borne mass spectrometer measurements during summer have revealed local H2O2 enhancements in the region of the clouds. Rocket-borne measurements of atomic O and O3 profiles in the presence of mesospheric clouds in the daytime are highly desirable to test the predictions of this model and our understanding of the genesis of mesospheric clouds.

  12. An extremely important discovery-the centre of the electron cloud of K atom does not coincide with the nucleus

    CERN Document Server

    You, Pei-Lin

    2009-01-01

    It is a general point of view that in the absence of an external field, the nucleus of an atom is at the centre of the electron cloud, so that all kinds of atoms do not have permanent electric dipole moment(EDM). In the fact, the idea is untested. Using two special capacitors containing Potassium vapor we discovered that the electric susceptibility Xe of K atoms is directly proportional to the density N, and inversely to the temperature T, as polar molecules. The experimental K material is supplied by Strem Chemicals Co. USA. We have distinguished between permanent and induced dipole moments carefully. There is good evidence that a ground state neutral K atom has a large permanent EDM, d(K)=2.53*10-29C.m, while d(H2O)=0.62 *10-29C.m for water molecule. New example of time-reversal violation occurred in K atoms. Why the linear Stark effect of K atoms has not been observed? The article discussed the question thoroughly. The linear Stark shift of K atoms is only 0.0041nm. It is so small, in fact, that a direct o...

  13. Efimov studies of an ultracold cloud of 39 K atoms in microgravity: Numerical modelling and experimental design

    Science.gov (United States)

    Mossman, Maren; Engels, Peter; D'Incao, Jose; Jin, Deborah; Cornell, Eric

    2016-05-01

    Ultracold atomic gases at or near quantum degeneracy provide a powerful tool for the investigation of few-body physics. A particularly intriguing few-body phenomenon is the existence of Efimov trimer states at large interatomic scattering lengths. These trimers are predicted to exhibit universal geometric scaling relations, but in practice the situation is complicated e.g. by finite-range and finite-temperature effects. While some Efimov trimers have already been experimentally observed by several groups in ground-based experiments, NASA's Cold Atom Laboratory (CAL) onboard the ISS will greatly enhance the experimentally accessible regimes by providing ultracold clouds of 39 K atoms with temperatures at or below 1 nK, low densities, and long observation times. We present results of numerical modelling and simulations that lay out Efimov experiments capitalizing on the particular strengths of CAL.

  14. Development of a cloud point extraction and preconcentration method for Cd and Ni prior to flame atomic absorption spectrometric determination

    Energy Technology Data Exchange (ETDEWEB)

    Manzoori, Jamshid L. [Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)]. E-mail: manzoori@tabrizu.ac.ir; Karim-Nezhad, Ghasem [Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2004-09-13

    In this work a new cloud point extraction (CPE) methodology was developed for the separation and preconcentration of cadmium and nickel. The analyte in the initial aqueous solution was complexed with dithizone and Triton X-114 was added as surfactant. After phase separation, based on the cloud point of the mixture, and dilution of the surfactant-rich phase with tetrahydrofuran (THF), the enriched analytes were determined by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions and preconcentration of only 10 ml of sample in the presence of 0.05% Triton X-114, the enhancement factors of 52 and 39 and the detection limits of 0.31 {mu}g l{sup -1} and 1.2 {mu}g l{sup -1} were obtained for cadmium and nickel respectively. The proposed method was applied satisfactorily to the determination of cadmium and nickel in water samples.

  15. Brownian motion of a matter-wave bright soliton moving through a thermal cloud of distinct atoms

    Science.gov (United States)

    McDonald, R. G.; Bradley, A. S.

    2016-06-01

    Taking an open quantum system approach, we derive a collective equation of motion for the dynamics of a matter-wave bright soliton moving through a thermal cloud of a distinct atomic species. The reservoir interaction involves energy transfer without particle transfer between the soliton and thermal cloud, thus damping the soliton motion without altering its stability against collapse. We derive a Langevin equation for the soliton center-of-mass velocity in the form of an Ornstein-Uhlenbeck process with analytical drift and diffusion coefficients. This collective motion is confirmed by simulations of the full stochastic projected Gross-Pitaevskii equation for the matter-wave field. The system offers a pathway for experimentally observing the elusive energy-damping reservoir interaction and a clear realization of collective Brownian motion for a mesoscopic superfluid droplet.

  16. Isomerization and fragmentation of acetonitrile upon interaction with N(4S) atoms: the chemistry of nitrogen in dense molecular clouds

    Science.gov (United States)

    Mencos, Alejandro; Krim, Lahouari

    2016-08-01

    We experimentally show that the reaction between ground state nitrogen atoms N(4S) and acetonitrile CH3CN can lead to two distinct chemical pathways that are both thermally activated at very low temperatures. First is CH3CN isomerization which produces CH3NC and H2CCNH. Second is CH3CN decomposition which produces HNC and CH3CNH+CN- fragments, with the possible release of H2. Our results reveal that the mobility of N(4S)-atoms is stimulated in the 3-11 K temperature range, and that its subsequent encounter with one acetonitrile molecule is sufficient for the aforementioned reactions to occur without the need for additional energy to be supplied to the CH3CN + N(4S) system. These findings shed more light on the nitrogen chemistry that can possibly take place in dense molecular clouds, which until now was thought to only involve high-energy processes and therefore be unlikely to occur in such cold and dark interstellar regions. The reaction pathways we propose in this study have very important astrochemical implications, as it was shown recently that the atomic nitrogen might be more abundant, in many interstellar icy grain mantles, than previously thought. Also, these reaction pathways can now be considered within dense molecular clouds, and possibly affect the branching ratios for N-bearing molecules computed in astrochemical modelling.

  17. Modelling the impact of noctilucent cloud formation on atomic oxygen and other minor constituents of the summer mesosphere

    Directory of Open Access Journals (Sweden)

    B. J. Murray

    2004-11-01

    Full Text Available The formation, evolution and eventual sublimation of noctilucent clouds (NLC could have a significant effect on the odd oxygen and hydrogen chemistry of the high latitude summer mesosphere. Three mechanisms are considered here: the direct uptake of atomic oxygen on the surface of the ice particles; the redistribution of water vapour, which changes the photochemical source of odd hydrogen species; and the direct photolysis of the ice particles themselves to produce odd hydrogen species in the gas phase. A 1-D photochemical model is employed to investigate the potential importance of these mechanisms. This shows, using the recently measured uptake coefficients of O on ice, that the heterogeneous removal of O on the surface of the cloud particles is too slow by at least a factor of 5×103 to compete with gas-phase O chemistry. The second and third mechanisms involve the solar Lyman-α photolysis of H2O in the gas and solid phase, respectively. During twilight, Lyman-α radiation is severely attenuated and these mechanisms are insignificant. In contrast, when the upper mesosphere is fully illuminated there is a dramatic impact on the O profile, with depletion of O at the base of the cloud layer of close to an order of magnitude. A correspondingly large depletion in O3 is also predicted, while H, OH, HO2 and H2O2 are found to be enhanced by factors of 3–5. In fact, rocket-borne mass spectrometer measurements during summer have revealed local H2O2 enhancements in the region of the clouds. Rocket-borne measurements of atomic O and O3 profiles in the presence of mesospheric clouds in the daytime are highly desirable to test the predictions of this model and our understanding of the genesis of mesospheric clouds.

  18. Improving The Accuracy Of Selection Of Bird Radar Echoes Against A Background Of Atomized Clouds And Atmospheric Inhomogeneities

    Directory of Open Access Journals (Sweden)

    Dinevich Leonid

    2015-12-01

    Full Text Available The algorithm for bird radar echo selection was developed in Israel and has been successfully used for many years to monitor birds in periods of massive intercontinental migration in order to ensure flight safety in civil and military aviation. However, it has been found that under certain meteorological conditions the bird echo selection algorithm does not filter out false signals formed by atomized clouds and atmospheric inhomogeneities. Although the algorithm is designed to identify and sift false signals, some useful echoes from smaller birds are erroneously sifted as well.

  19. Molecular and atomic fractionation effects in the NGC 1977 molecular cloud

    OpenAIRE

    Minchin, Nigel R.; White, Glenn J.

    1995-01-01

    The photon-dominated region (PDR) associated with the NGC 1977 molecular cloud has been observed at high resolution in the 13CO and C18O J=2→1 and the [CI] 3P1-3P0 lines. The N(13CO)/N(C18O) ratio has been plotted against visual extinction (Av) and fits a power law relation. The highest values, as expected, occur for observed positions with the lowest derived extinction, with N(13CO)/N(C18O) exceeding the terrestrial value (5.5) for Av≤60 magnitudes. In the outermost parts of the cloud (Av≤20...

  20. Cloud condensation nucleus (CCN behavior of organic aerosol particles generated by atomization of water and methanol solutions

    Directory of Open Access Journals (Sweden)

    T. A. Rissman

    2007-06-01

    Full Text Available Cloud condensation nucleus (CCN experiments were carried out for malonic acid, succinic acid, oxalacetic acid, DL-malic acid, glutaric acid, DL-glutamic acid monohydrate, and adipic acid, using both water and methanol as atomization solvents, at three operating supersaturations (0.11%, 0.21%, and 0.32% in the Caltech three-column CCN instrument (CCNC3. Predictions of CCN behavior for five of these compounds were made using the Aerosol Diameter Dependent Equilibrium Model (ADDEM. The experiments presented here expose important considerations associated with the laboratory measurement of the CCN behavior of organic compounds. Choice of atomization solvent results in significant differences in CCN activation for some of the compounds studied, which could result from residual solvent, particle morphology differences, and chemical reactions between the particle and gas phases. Also, significant changes in aerosol size distribution occurred after classification in a differential mobility analyzer (DMA for malonic acid and glutaric acid, preventing confident interpretation of experimental data for these two compounds. Filter analysis of adipic acid atomized from methanol solution indicates that gas-particle phase reactions may have taken place after atomization and before methanol was removed from the sample gas stream. Careful consideration of these experimental issues is necessary for successful design and interpretation of laboratory CCN measurements.

  1. Cloud condensation nucleus (CCN behavior of organic aerosol particles generated by atomization of water and methanol solutions

    Directory of Open Access Journals (Sweden)

    T. A. Rissman

    2006-12-01

    Full Text Available Cloud condensation nucleus (CCN experiments were carried out for malonic acid, succinic acid, oxalacetic acid, DL-malic acid, glutaric acid, DL-glutamic acid monohydrate, and adipic acid, using both water and methanol as atomization solvents, at three operating supersaturations (0.11% 0.21%, and 0.32% in the Caltech three-column CCN instrument (CCNC3. Predictions of CCN behavior for five of these compounds were made using the Aerosol Diameter Dependent Equilibrium Model (ADDEM. The experiments presented here expose important considerations associated with the laboratory measurement of the CCN behavior of organic compounds. Choice of atomization solvent results in significant differences in CCN activation for some of the compounds studied, which could result from residual solvent, particle morphology differences, and chemical reactions between the particle and gas phases. Also, significant changes in aerosol size distribution occurred after classification in a differential mobility analyzer (DMA for malonic acid and glutaric acid. Filter analysis of adipic acid atomized from methanol solution indicates that gas-particle phase reactions may have taken place after atomization and before the methanol was removed from the sample gas stream. Careful consideration of these experimental issues is necessary for successful design and interpretation of laboratory CCN measurements.

  2. Photo-association of cold cesium atoms. Formation and characterisation of a cold cloud of diatomic cesium molecules

    International Nuclear Information System (INIS)

    In a photo-association process, two colliding cold cesium atoms absorb one photon to form an ultracold molecule, electronically excited in a well defined ro-vibration level. Because of the small initial kinetic energy of the free atoms, the photo-association is resonant and permits high resolution spectroscopy of long-range states. We report spectra for states correlated to the excited limit 6S+6P. The 1u (6S+6P3/2) state is a pure long-range molecules. It hardly consists in a molecule, but rather in a pair of two atoms linked at 1, 5 nm by the multipolar electrostatic interaction. The intensity modulation of spectral lines for a given vibrational progression reflects the nodal structure of the radial s-wave function of two ground state atoms. The photo-association of the state 0g-(6S +6P3/2) of polarized atoms permits determining the scattering length of the triplet state of cesium (aT = -530 a0) and the Van der Waals parameter of the molecular ground state (C6 = 6510 u.a.). Photo-association of cold cesium atoms also leads to the formation of translationally cold molecules in singlet and triplet fundamental states after spontaneous emission of the excited molecules. Various schemes are characterized. The particular double-well shape of 0g-(6S+6P3/2) and 1u(6S+6P3/2) states creates a Condon point at intermediate distance. These states constitute ideal cases for very efficient formation of cold molecules. The cold molecular cloud is analyzed: temperatures as low as 20 micro-Kelvin are measured and the distribution of the ro-vibrational levels is studied. The efficiencies of the photo-association process and of the formation of cold molecules are measured, and compared with theoretical calculations. (author)

  3. Cold and warm atomic gas around the Perseus molecular cloud I: Basic Properties

    CERN Document Server

    Stanimirovic, Snezana; Lee, Min-Young; Heiles, Carl; Miller, Jesse

    2014-01-01

    (Abridged) Using the Arecibo Observatory we have obtained neutral hydrogen (HI) absorption and emission spectral pairs in the direction of 26 background radio continuum sources in the vicinity of the Perseus molecular cloud. Strong absorption lines were detected in all cases allowing us to estimate spin temperature (T_s) and optical depth for 107 individual Gaussian components along these lines of sight. Basic properties of individual HI clouds (spin temperature, optical depth, and the column density of the cold and warm neutral medium, CNM and WNM) in and around Perseus are very similar to those found for random interstellar lines of sight sampled by the Millennium HI survey. This suggests that the neutral gas found in and around molecular clouds is not atypical. However, lines of sight in the vicinity of Perseus have on average a higher total HI column density and the CNM fraction, suggesting an enhanced amount of cold HI relative to an average interstellar field. Our estimated optical depth and spin temper...

  4. Cold and warm atomic gas around the Perseus molecular cloud. I. Basic properties

    International Nuclear Information System (INIS)

    Using the Arecibo Observatory, we have obtained neutral hydrogen (HI) absorption and emission spectral pairs in the direction of 26 background radio continuum sources in the vicinity of the Perseus molecular cloud. Strong absorption lines were detected in all cases, allowing us to estimate spin temperature (Ts ) and optical depth for 107 individual Gaussian components along these lines of sight. Basic properties of individual H I clouds (spin temperature, optical depth, and the column density of the cold and warm neutral medium (CNM and WNM), respectively) in and around Perseus are very similar to those found for random interstellar lines of sight sampled by the Millennium H I survey. This suggests that the neutral gas found in and around molecular clouds is not atypical. However, lines of sight in the vicinity of Perseus have, on average, a higher total H I column density and the CNM fraction, suggesting an enhanced amount of cold H I relative to an average interstellar field. Our estimated optical depth and spin temperature are in stark contrast with the recent attempt at using Planck data to estimate properties of the optically thick H I. Only ∼15% of lines of sight in our study have a column density weighted average spin temperature lower than 50 K, in comparison with ≳ 85% of Planck's sky coverage. The observed CNM fraction is inversely proportional to the optical depth weighted average spin temperature, in excellent agreement with the recent numerical simulations by Kim et al. While the CNM fraction is, on average, higher around Perseus relative to a random interstellar field, it is generally low, between 10%-50%. This suggests that extended WNM envelopes around molecular clouds and/or significant mixing of CNM and WNM throughout molecular clouds are present and should be considered in the models of molecule and star formation. Our detailed comparison of H I absorption with CO emission spectra shows that only 3 of the 26 directions are clear

  5. Determination of ultra-trace aluminum in human albumin by cloud point extraction and graphite furnace atomic absorption spectrometry

    International Nuclear Information System (INIS)

    A cloud point extraction (CPE) method for the preconcentration of ultra-trace aluminum in human albumin prior to its determination by graphite furnace atomic absorption spectrometry (GFAAS) had been developed in this paper. The CPE method was based on the complex of Al(III) with 1-(2-pyridylazo)-2-naphthol (PAN) and Triton X-114 was used as non-ionic surfactant. The main factors affecting cloud point extraction efficiency, such as pH of solution, concentration and kind of complexing agent, concentration of non-ionic surfactant, equilibration temperature and time, were investigated in detail. An enrichment factor of 34.8 was obtained for the preconcentration of Al(III) with 10 mL solution. Under the optimal conditions, the detection limit of Al(III) was 0.06 ng mL-1. The relative standard deviation (n = 7) of sample was 3.6%, values of recovery of aluminum were changed from 92.3% to 94.7% for three samples. This method is simple, accurate, sensitive and can be applied to the determination of ultra-trace aluminum in human albumin.

  6. Speciation of silver nanoparticles and Ag(I) species using cloud point extraction followed by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Silver nanoparticles in the presence of Triton-X114 were extracted into a micellar phase obtained after incubation at 40 °C for 10 min followed by centrifugation. After injection of an aliquot (30 μL) of the surfactant-rich phase into the electrothermal atomizer, the enrichment effect due to cloud point extraction allowed a detection limit of 2 ng L−1 silver to be achieved. The preconcentration factor was 242, and the repeatability for ten measurements at a 50 ng L−1 silver level was 4.6%. Ag(I) species were adsorbed onto the silver nanoparticles and were also extracted in the micellar phase. The incorporation of 0.01 mol L−1 ammonium thiocyanate to the sample solution prevented the extraction of Ag(I) species. Speciation was carried out using two extractions, one in the absence and the other in the presence of thiocyanate, the concentration of Ag(I) species being obtained by difference. The procedure was applied to the determination of silver nanoparticles and Ag(I) species in waters and in lixiviates obtained from sticking plasters and cleaning cloths. - Highlights: • Silver nanoparticles and Ag(I) species are separated into a surfactant-rich phase. • The Ag(I) species are not extracted in the presence of thiocyanate. • The cloud point extraction of two aliquots allows speciation to be carried out. • Extreme sensitivity (detection limit 2 ng L−1) is achieved

  7. Spin Diffusion in Trapped Clouds of Cold Atoms with Resonant Interactions

    DEFF Research Database (Denmark)

    Bruun, Georg Morten; Pethick, C. J.

    2011-01-01

    We show that puzzling recent experimental results on spin diffusion in a strongly interacting atomic gas may be understood in terms of the predicted spin diffusion coefficient for a generic strongly interacting system. Three important features play a central role: (a) Fick’s law for diffusion must...

  8. An important discovery - with no electric field, the center of the electron cloud of K atom does not coincide with the nucleus

    OpenAIRE

    You, Pei-Lin

    2009-01-01

    It is a general point of view that in the absence of an external field, the nucleus of an atom is at the center of the electron cloud, so that all kinds of atoms do not have permanent electric dipole moment (EDM). In the fact, the idea is untested. Using two special capacitors containing Potassium vapor we discovered that the electric susceptibility Xe of K atoms is directly proportional to the density N, and inversely to the temperature T, as polar molecules. The experimental K material with...

  9. Atoms

    Institute of Scientific and Technical Information of China (English)

    刘洪毓

    2007-01-01

    Atoms(原子)are all around us.They are something like the bricks (砖块)of which everything is made. The size of an atom is very,very small.In just one grain of salt are held millions of atoms. Atoms are very important.The way one object acts depends on what

  10. Physics of Ultra-Cold Matter Atomic Clouds, Bose-Einstein Condensates and Rydberg Plasmas

    CERN Document Server

    Mendonça, J T

    2013-01-01

    The advent of laser cooling of atoms led to the discovery of ultra-cold matter, with temperatures below liquid Helium, which displays a variety of new physical phenomena. Physics of Ultra-Cold Matter gives an overview of this recent area of science, with a discussion of its main results and a description of its theoretical concepts and methods. Ultra-cold matter can be considered in three distinct phases: ultra-cold gas, Bose Einstein condensate, and Rydberg plasmas. This book gives an integrated view of this new area of science at the frontier between atomic physics, condensed matter, and plasma physics. It describes these three distinct phases while exploring the differences, as well as the sometimes unexpected similarities, of their respective theoretical methods. This book is an informative guide for researchers, and the benefits are a result from an integrated view of a very broad area of research, which is limited in previous books about this subject. The main unifying tool explored in this book is the ...

  11. Cloud point extraction for trace inorganic arsenic speciation analysis in water samples by hydride generation atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shan, E-mail: ls_tuzi@163.com; Wang, Mei, E-mail: wmei02@163.com; Zhong, Yizhou, E-mail: yizhz@21cn.com; Zhang, Zehua, E-mail: kazuki.0101@aliyun.com; Yang, Bingyi, E-mail: e_yby@163.com

    2015-09-01

    A new cloud point extraction technique was established and used for the determination of trace inorganic arsenic species in water samples combined with hydride generation atomic fluorescence spectrometry (HGAFS). As(III) and As(V) were complexed with ammonium pyrrolidinedithiocarbamate and molybdate, respectively. The complexes were quantitatively extracted with the non-ionic surfactant (Triton X-114) by centrifugation. After addition of antifoam, the surfactant-rich phase containing As(III) was diluted with 5% HCl for HGAFS determination. For As(V) determination, 50% HCl was added to the surfactant-rich phase, and the mixture was placed in an ultrasonic bath at 70 °C for 30 min. As(V) was reduced to As(III) with thiourea–ascorbic acid solution, followed by HGAFS. Under the optimum conditions, limits of detection of 0.009 and 0.012 μg/L were obtained for As(III) and As(V), respectively. Concentration factors of 9.3 and 7.9, respectively, were obtained for a 50 mL sample. The precisions were 2.1% for As(III) and 2.3% for As(V). The proposed method was successfully used for the determination of trace As(III) and As(V) in water samples, with satisfactory recoveries. - Highlights: • Cloud point extraction was firstly established to determine trace inorganic arsenic(As) species combining with HGAFS. • Separate As(III) and As(V) determinations improve the accuracy. • Ultrasonic release of complexed As(V) enables complete As(V) reduction to As(III). • Direct HGAFS analysis can be performed.

  12. Cloud point extraction for trace inorganic arsenic speciation analysis in water samples by hydride generation atomic fluorescence spectrometry

    International Nuclear Information System (INIS)

    A new cloud point extraction technique was established and used for the determination of trace inorganic arsenic species in water samples combined with hydride generation atomic fluorescence spectrometry (HGAFS). As(III) and As(V) were complexed with ammonium pyrrolidinedithiocarbamate and molybdate, respectively. The complexes were quantitatively extracted with the non-ionic surfactant (Triton X-114) by centrifugation. After addition of antifoam, the surfactant-rich phase containing As(III) was diluted with 5% HCl for HGAFS determination. For As(V) determination, 50% HCl was added to the surfactant-rich phase, and the mixture was placed in an ultrasonic bath at 70 °C for 30 min. As(V) was reduced to As(III) with thiourea–ascorbic acid solution, followed by HGAFS. Under the optimum conditions, limits of detection of 0.009 and 0.012 μg/L were obtained for As(III) and As(V), respectively. Concentration factors of 9.3 and 7.9, respectively, were obtained for a 50 mL sample. The precisions were 2.1% for As(III) and 2.3% for As(V). The proposed method was successfully used for the determination of trace As(III) and As(V) in water samples, with satisfactory recoveries. - Highlights: • Cloud point extraction was firstly established to determine trace inorganic arsenic(As) species combining with HGAFS. • Separate As(III) and As(V) determinations improve the accuracy. • Ultrasonic release of complexed As(V) enables complete As(V) reduction to As(III). • Direct HGAFS analysis can be performed

  13. Species selective preconcentration and quantification of gold nanoparticles using cloud point extraction and electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Highlights: ► We optimized cloud point extraction and ET-AAS parameters for Au-NPs measurement. ► A selective ligand (sodium thiosulphate) is introduced for species separation. ► A limit of detection of 5 ng Au-NP per L is achieved for aqueous samples. ► Measurement of samples with high natural organic mater content is possible. ► Real water samples including wastewater treatment plant effluent were analyzed. - Abstract: The determination of metallic nanoparticles in environmental samples requires sample pretreatment that ideally combines pre-concentration and species selectivity. With cloud point extraction (CPE) using the surfactant Triton X-114 we present a simple and cost effective separation technique that meets both criteria. Effective separation of ionic gold species and Au nanoparticles (Au-NPs) is achieved by using sodium thiosulphate as a complexing agent. The extraction efficiency for Au-NP ranged from 1.01 ± 0.06 (particle size 2 nm) to 0.52 ± 0.16 (particle size 150 nm). An enrichment factor of 80 and a low limit of detection of 5 ng L−1 is achieved using electrothermal atomic absorption spectrometry (ET-AAS) for quantification. TEM measurements showed that the particle size is not affected by the CPE process. Natural organic matter (NOM) is tolerated up to a concentration of 10 mg L−1. The precision of the method expressed as the standard deviation of 12 replicates at an Au-NP concentration of 100 ng L−1 is 9.5%. A relation between particle concentration and the extraction efficiency was not observed. Spiking experiments showed a recovery higher than 91% for environmental water samples.

  14. Atoms

    International Nuclear Information System (INIS)

    Completed by recent contributions on various topics (atoms and the Brownian motion, the career of Jean Perrin, the evolution of atomic physics since Jean Perrin, relationship between scientific atomism and philosophical atomism), this book is a reprint of a book published at the beginning of the twentieth century in which the author addressed the relationship between atomic theory and chemistry (molecules, atoms, the Avogadro hypothesis, molecule structures, solutes, upper limits of molecular quantities), molecular agitation (molecule velocity, molecule rotation or vibration, molecular free range), the Brownian motion and emulsions (history and general features, statistical equilibrium of emulsions), the laws of the Brownian motion (Einstein's theory, experimental control), fluctuations (the theory of Smoluchowski), light and quanta (black body, extension of quantum theory), the electricity atom, the atom genesis and destruction (transmutations, atom counting)

  15. Giant Gas Cloud Made of Atoms Formed in First Stars Revealed in Universe's Most Distant Quasar

    Science.gov (United States)

    2003-07-01

    Astronomers studying the most distant quasar yet found in the Universe have discovered a massive reservoir of gas containing atoms made in the cores of some of the first stars ever formed. The carbon-monoxide gas was revealed by the National Science Foundation's Very Large Array (VLA) and the Plateau de Bure radio interferometer in Europe. The gas, along with the young galaxy containing it, is seen as it was when the Universe was only one-sixteenth its current age, just emerging from the primeval "Dark Ages" before light could travel freely through the cosmos. VLA Image of Quasar VLA Image of J1148+5251 CREDIT: NRAO/AUI/NSF (Click on Image for Larger Version) "Our discovery of this much carbon monoxide gas in such an extremely distant and young galaxy is surprising. It means that, even at a very early time in the history of the Universe, galaxies already had huge amounts of molecular gas that would eventually form new generations of stars," said Chris Carilli, of the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. The distant galaxy, dubbed J1148+5251, contains a bright quasar powered by a black hole at least a billion times more massive than the Sun. The galaxy is seen as it was only 870 million years after the Big Bang. The Universe now is 13.7 billion years old. J1148+5251 would have been among the first luminous objects in the Universe. The original atoms formed in the Universe within the first three minutes of the Big Bang were only hydrogen and helium. Carbon and oxygen -- the atoms making up carbon monoxide -- had to be made in the thermonuclear furnaces at the cores of the earliest stars. "The carbon and oxygen atoms in the gas we detected were made by some of the first stars ever formed, only about 650 million years after the Big Bang. In the next 200 million years or so, those stars -- probably very different stars from those we see today -- exploded as supernovae, spreading the carbon and oxygen out into space. Those atoms then cooled

  16. Determination of platinum traces contamination by graphite furnace atomic absorption spectrometry after preconcentration by cloud point extraction

    International Nuclear Information System (INIS)

    A simple and sensitive method is described for the determination of platinum surface contamination originating from cisplatin, carboplatin and oxaliplatin. Following extraction from swabs and preconcentration with the cloud point extraction (CPE) method, detection was by graphite furnace atomic absorption spectrometry (GFAAS). After desorption of platinum compounds from the swab, CPE involved on preconcentration of platinum in aqueous solution with diethyldithiocarbamate (DDTC) as chelating agent and Triton X-114 as extraction medium. DDTC is not only a chelating agent, but may also be a good candidate for the inactivation of platinum compounds. DDTC is recommended by the Word Health Organization (WHO) for the destruction of platinum-based anticancer drugs. The main factors affecting CPE efficiency, pH of the sample solution, concentrations of DDTC and Triton X-114, equilibration temperature and incubation time, were evaluated in order to enhance sensitivity of the method. The desorption of platinum compounds from the swab was investigated in parallel. Since platinum is bound to DDTC, it must exchange with copper in order to enhance platinum atomizing by GFAAS. A preconcentration factor of 29 was obtained for 10 mL of a platinum solution at 10 μg mL-1. In optimal conditions, the limit of detection was 0.2 ng mL-1, corresponding to 2.0 ng of platinum metal on the swab. Absorbance was linear between 0.7 and 15 ng mL-1. The proposed method was applied for the determination of surface contamination by platinum compounds with correct results.

  17. Determination of trace mercury in environmental samples by cold vapor atomic fluorescence spectrometry after cloud point extraction

    International Nuclear Information System (INIS)

    A sensitive method is presented for the determination of ultra-trace levels of mercury using cold vapor atomic fluorescence spectrometry along with cloud point extraction. Preconcentration is based on the complexation of Hg(II) by dithizone, followed by micelle-mediated extraction of the complex using the surfactant Triton X-114. Foaming, which is always observed when generating vapor mercury in the presence of surfactant, was strongly reduced by using SnCl2 as a reducing reagent, and a homemade gas-liquid separator. Variables that affect the assay were optimized. These included pH value, concentration of chelating reagent, concentration of Triton X-114, equilibration temperature and time. The preconcentration of a 45-mL sample gave an enhancement factor of 29. The calibration graph is linear in the range from 0. 05 to 5. 0 ng mL-1 with a correlation coefficient of 0. 9991. The limit of detection obtained under the optimal conditions is 5 pg mL-1. The relative standard deviation for seven replicate determinations at 0. 5 ng mL-1 level is 5. 2%. The method was successfully applied to the determination of Hg in real samples. (author)

  18. Cloud Point Extraction Using Tergitol TMN-6 of Gold(III)in Real Samples by Flame Atomic Absorption Spectrometry Determination

    International Nuclear Information System (INIS)

    A simple, safe and rapid method on the basis of cloud point extraction (CPE) with tergitol TMN-6 had been used for the preconcentration and extraction of gold(Au) ion in selenium reduction solution sample prior to flame atomic absorption spectrometry (FAAS).Pyrrolidine dithio formic acid salt (PDFAS) which was regarded as a selective complexing agent could formed stable Au-complex with Au ion, and Au-complex could be extracted by TMN-6 at a short time. Some influencing factors such as sample pH, concentration of TMN-6, concentration of PDFAS and the effect of foreign ions were further researched .Under the optimum conditions, the limit of detection (LOD) was 1.3 meu g L/sup -1/, the calibration graph was linear in the range of 0-500 meu g/L and the relative standard deviation (RSD%) was 2.0%(n=8). The CPE method had been shown to be a useful and effective methodology for the separation of Au, with a preconcentration factor of 30. The recoveries of the spiked Au(?) ions were got in the range 95-103%. (author)

  19. GOT C+ Survey of [CII] 158 Micrometer Emission: Atomic to Molecular Cloud Transitions in the Inner Galaxy

    Science.gov (United States)

    Velusamy, T.; Langer, W. D.; Willacy, K.; Pineda, J. L.; Goldsmith, P. F.

    2012-01-01

    We present the results of the distribution of CO-dark H2 gas in a sample of 2200 interstellar clouds in the inner Galaxy (l = 90 deg to +57 deg) detected in the velocity resolved [CII] spectra observed in the GOT C+ survey using the Herschel HIFI. We analyze the [CII] intensities along with the ancillary HI, (12)CO and (13)CO data for each cloud to determine their evolutionary state and to derive the H2 column densities in the C(+) and C(+)/CO transition layers in the cloud. We discuss the overall Galactic distribution of the [CII] clouds and their properties as a function Galactic radius. GOT C+ results on the global distribution of [CII] clouds and CO-dark H2 gas traces the FUV and star formation rates in the Galactic disk.

  20. Selective cloud point extraction and preconcentration of trace amounts of silver as a dithizone complex prior to flame atomic absorption spectrometric determination

    Energy Technology Data Exchange (ETDEWEB)

    Manzoori, Jamshid L.; Karim-Nezhad, Ghasem

    2003-05-19

    Dithizone (diphenylthiocarbazone) was used as a complexing agent in cloud point extraction for the first time and applied for selective preconcentration of trace amounts of silver. The analyte in the initial aqueous solution was acidified with sulfuric acid (pH<1) and Triton X-114 was added as a surfactant. After phase separation, based on the cloud point separation of the mixture, the surfactant rich phase was diluted with tetrahydrofuran (THF) and the analyte determined in the enriched solution by flame atomic absorption spectrometry. After optimization of the complexation and extraction conditions, a preconcentration factor of 43 was obtained for only 10 ml of sample. The analytical curve was linear in the range of 3-200 ng ml{sup -1} and the limit of detection was 0.56 ng ml{sup -1}. The proposed method was applied to the determination of silver in water samples.

  1. Rydberg Matter clusters of alkali metal atoms: the link between meteoritic matter, polar mesosphere summer echoes (PMSE), sporadic sodium layers, polar mesospheric clouds (PMCs, NLCs), and ion chemistry

    CERN Document Server

    Olofson, Frans; Holmlid, Leif

    2010-01-01

    A material exists which links together the influx of meteoritic matter from interplanetary space, the polar mesosphere summer echoes (PMSE), the sporadic sodium layers, the polar mesospheric clouds (PMCs, NLCs), and the observed ion chemistry in the mesosphere. The evidence in these research fields is here analyzed and found to agree well with the properties of Rydberg Matter (RM). This material has been studied with numerous methods in the laboratory. Alkali atoms, mainly Na, reach the mesosphere in the form of interplanetary (meteoritic, cometary) dust. The planar RM clusters NaN usually contain N = 19, 37 or 61 atoms, and have the density of air at 90 km altitude where they float. The diameters of the clusters are 10-100 nm from laboratory high precision radio frequency spectroscopic studies. Such experiments show that RM clusters interact strongly with radar frequencies: this explains the radio frequency heating and reflection studies of PMSE layers. The clusters give the low temperature in the mesosphere...

  2. Determination of ultra trace amounts of bismuth in biological and water samples by electrothermal atomic absorption spectrometry (ET-AAS) after cloud point extraction

    Energy Technology Data Exchange (ETDEWEB)

    Shemirani, Farzaneh; Baghdadi, Majid; Ramezani, Majid; Jamali, Mohammad Reza

    2005-04-04

    A new approach for a cloud point extraction electrothermal atomic absorption spectrometric method was used for determining bismuth. The aqueous analyte was acidified with sulfuric acid (pH 3.0-3.5). Triton X-114 was added as a surfactant and dithizone was used as a complexing agent. After phase separation at 50 deg. C based on the cloud point separation of the mixture, the surfactant-rich phase was diluted using tetrahydrofuran (THF). Twenty microliters of the enriched solution and 10 {mu}l of 0.1% (w/v) Pd(NO{sub 3}){sub 2} as chemical modifier were dispersed into the graphite tube and the analyte determined by electrothermal atomic absorption spectrometry. After optimizing extraction conditions and instrumental parameters, a preconcentration factor of 196 was obtained for a sample of only 10 ml. The detection limit was 0.02 ng ml{sup -1} and the analytical curve was linear for the concentration range of 0.04-0.60 ng ml{sup -1}. Relative standard deviations were <5%. The method was successfully applied for the extraction and determination of bismuth in tap water and biological samples (urine and hair)

  3. Application of dual-cloud point extraction for the trace levels of copper in serum of different viral hepatitis patients by flame atomic absorption spectrometry: A multivariate study

    Science.gov (United States)

    Arain, Salma Aslam; Kazi, Tasneem G.; Afridi, Hassan Imran; Abbasi, Abdul Rasool; Panhwar, Abdul Haleem; Naeemullah; Shanker, Bhawani; Arain, Mohammad Balal

    2014-12-01

    An efficient, innovative preconcentration method, dual-cloud point extraction (d-CPE) has been developed for the extraction and preconcentration of copper (Cu2+) in serum samples of different viral hepatitis patients prior to couple with flame atomic absorption spectrometry (FAAS). The d-CPE procedure was based on forming complexes of elemental ions with complexing reagent 1-(2-pyridylazo)-2-naphthol (PAN), and subsequent entrapping the complexes in nonionic surfactant (Triton X-114). Then the surfactant rich phase containing the metal complexes was treated with aqueous nitric acid solution, and metal ions were back extracted into the aqueous phase, as second cloud point extraction stage, and finally determined by flame atomic absorption spectrometry using conventional nebulization. The multivariate strategy was applied to estimate the optimum values of experimental variables for the recovery of Cu2+ using d-CPE. In optimum experimental conditions, the limit of detection and the enrichment factor were 0.046 μg L-1 and 78, respectively. The validity and accuracy of proposed method were checked by analysis of Cu2+ in certified sample of serum (CRM) by d-CPE and conventional CPE procedure on same CRM. The proposed method was successfully applied to the determination of Cu2+ in serum samples of different viral hepatitis patients and healthy controls.

  4. Combination of cloud point extraction and flame atomic absorption spectrometry for preconcentration and determination of nickel and manganese ions in water and food samples

    International Nuclear Information System (INIS)

    A simple, rapid, inexpensive, and nonpolluting cloud point extraction (CPE) technique has been improved for the preconcentration and determination of nickel and manganese. After complexation with p-nitrophenylazoresorcinol (Magneson I), the analytes could be competitively extracted in a surfactant octylphenoxy polyethoxyethanol (Triton X-114), prior to determination by flame atomic absorption spectrometry (FAAS). The effects of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on CPE were studied. Under the optimum conditions, preconcentration of a 25 mL sample solution permitted the detection of 2.7 ng mL-1 Ni2+ and 2.9 ng mL-1 Mn2+ with enrichment factors of 17 and 19 for Ni2+ and Mn2+, respectively. The developed method was applied to the determination of trace nickel and manganese in water and food samples with satisfactory results.

  5. Cloud point extraction combined with electrothermal atomic absorption spectrometry for the speciation of antimony(III) and antimony(V) in food packaging materials

    International Nuclear Information System (INIS)

    A simple, sensitive method for the speciation of inorganic antimony by cloud point extraction combined with electrothermal atomic absorption spectrometry (ETAAS) is presented and evaluated. The method based on the fact that formation of a hydrophobic complex of antimony(III) with ammonium pyrrolidine dithiocarbamate (APDC) at pH 5.0 and subsequently the hydrophobic complex enter into surfactant-rich phase, whereas antimony(V) remained in aqueous solutions. Antimony(III) in surfactant-rich phase was analyzed by ETAAS after dilution by 0.2 mL nitric acid in methanol (0.1 M), and antimony(V) was calculated by subtracting antimony(III) from the total antimony after reducing antimony(V) to antimony(III) by L-cysteine. The main factors affecting the cloud point extraction, such as pH, concentration of APDC and Triton X-114, equilibrium temperature and incubation time, sample volume were investigated in detail. Under the optimum conditions, the detection limit (3σ) of the proposed method was 0.02 ng mL-1 for antimony(III), and the relative standard deviation was 7.8% (c = 1.0 ng mL-1, n = 7). The proposed method was successfully applied to speciation of inorganic antimony in the leaching solutions of different food packaging materials with satisfactory results.

  6. Cloud point extraction combined with electrothermal atomic absorption spectrometry for the speciation of antimony(III) and antimony(V) in food packaging materials.

    Science.gov (United States)

    Jiang, Xiuming; Wen, Shengping; Xiang, Guoqiang

    2010-03-15

    A simple, sensitive method for the speciation of inorganic antimony by cloud point extraction combined with electrothermal atomic absorption spectrometry (ETAAS) is presented and evaluated. The method based on the fact that formation of a hydrophobic complex of antimony(III) with ammonium pyrrolidine dithiocarbamate (APDC) at pH 5.0 and subsequently the hydrophobic complex enter into surfactant-rich phase, whereas antimony(V) remained in aqueous solutions. Antimony(III) in surfactant-rich phase was analyzed by ETAAS after dilution by 0.2 mL nitric acid in methanol (0.1M), and antimony(V) was calculated by subtracting antimony(III) from the total antimony after reducing antimony(V) to antimony(III) by l-cysteine. The main factors affecting the cloud point extraction, such as pH, concentration of APDC and Triton X-114, equilibrium temperature and incubation time, sample volume were investigated in detail. Under the optimum conditions, the detection limit (3 sigma) of the proposed method was 0.02 ng mL(-1) for antimony(III), and the relative standard deviation was 7.8% (c=1.0 ng mL(-1), n=7). The proposed method was successfully applied to speciation of inorganic antimony in the leaching solutions of different food packaging materials with satisfactory results. PMID:19853991

  7. Preconcentration and determination of vanadium and molybdenum in milk, vegetables and foodstuffs by ultrasonic-thermostatic-assisted cloud point extraction coupled to flame atomic absorption spectrometry.

    Science.gov (United States)

    Gürkan, Ramazan; Korkmaz, Sema; Altunay, Nail

    2016-08-01

    A new ultrasonic-thermostatic-assisted cloud point extraction procedure (UTA-CPE) was developed for preconcentration at the trace levels of vanadium (V) and molybdenum (Mo) in milk, vegetables and foodstuffs prior to determination via flame atomic absorption spectrometry (FAAS). The method is based on the ion-association of stable anionic oxalate complexes of V(V) and Mo(VI) with [9-(diethylamino)benzo[a]phenoxazin-5-ylidene]azanium; sulfate (Nile blue A) at pH 4.5, and then extraction of the formed ion-association complexes into micellar phase of polyoxyethylene(7.5)nonylphenyl ether (PONPE 7.5). The UTA-CPE is greatly simplified and accelerated compared to traditional cloud point extraction (CPE). The analytical parameters optimized are solution pH, the concentrations of complexing reagents (oxalate and Nile blue A), the PONPE 7.5 concentration, electrolyte concentration, sample volume, temperature and ultrasonic power. Under the optimum conditions, the calibration curves for Mo(VI) and V(V) are obtained in the concentration range of 3-340µgL(-1) and 5-250µgL(-1) with high sensitivity enhancement factors (EFs) of 145 and 115, respectively. The limits of detection (LODs) for Mo(VI) and V(V) are 0.86 and 1.55µgL(-1), respectively. The proposed method demonstrated good performances such as relative standard deviations (as RSD %) (≤3.5%) and spiked recoveries (95.7-102.3%). The accuracy of the method was assessed by analysis of two standard reference materials (SRMs) and recoveries of spiked solutions. The method was successfully applied into the determination of trace amounts of Mo(VI) and V(V) in milk, vegetables and foodstuffs with satisfactory results. PMID:27216654

  8. Cloud point extraction and flame atomic absorption spectrometric determination of cadmium(II), lead(II), palladium(II) and silver(I) in environmental samples

    International Nuclear Information System (INIS)

    The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of cadmium(II), lead(II), palladium(II) and silver(I). The analytical procedure involved the formation of understudy metals complex with bis((1H-benzo [d] imidazol-2yl)ethyl) sulfane (BIES), and quantitatively extracted to the phase rich in octylphenoxypolyethoxyethanol (Triton X-114) after centrifugation. Methanol acidified with 1 mol L-1 HNO3 was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). The concentration of BIES, pH and amount of surfactant (Triton X-114) was optimized. At optimum conditions, the detection limits of (3 sdb/m) of 1.4, 2.8, 1.6 and 1.4 ng mL-1 for Cd2+, Pb2+, Pd2+ and Ag+ along with preconcentration factors of 30 and enrichment factors of 48, 39, 32 and 42 for Cd2+, Pb2+, Pd2+ and Ag+, respectively, were obtained. The proposed cloud point extraction has been successfully applied for the determination of metal ions in real samples with complicated matrix such as radiology waste, vegetable, blood and urine samples.

  9. Cloud Point Extraction for the Determination of Trace Amounts of Cobalt in Water and Food Samples by Flame Atomic Absorption Spectrometry

    Directory of Open Access Journals (Sweden)

    Shangzhi Wang

    2013-01-01

    Full Text Available A cloud point extraction (CPE procedure which was developed for the separation and preconcentration of trace amounts of cobalt is combined with flame atomic absorption spectrometry (FAAS to determine trace amounts of cobalt in water and food samples. The procedure is based on the formation of the hydrophobic complex between Co(II and 4-methoxy-2-sulfo-benzenediazoaminoazo-benzene (MOSDAA followed by its extraction into a Triton X-114 surfactant-rich phase. The parameters such as pH of sample, concentrations of MOSDAA and Triton X-114, equilibrium temperature, and equilibrium time, which affect both complexation and extraction, are optimized. Under the selected optimum conditions, the preconcentration of 10.0 mL, 0.1 μg mL−1 Co(II solution results in a limit of detection of 0.47 ng mL−1 (3σ and an enrichment factor of 19. A relative standard deviation of 2.78% (,  μg mL−1 for the determination of Co(II is obtained. The proposed method was applied for the determination of trace amounts of cobalt in river water and millet samples with satisfactory results.

  10. Cloud point extraction and flame atomic absorption spectrometric determination of cadmium(II), lead(II), palladium(II) and silver(I) in environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Ghaedi, Mehrorang, E-mail: m_ghaedi@mail.yu.ac.ir [Chemistry Department, Yasouj University, Yasouj 75914-353 (Iran, Islamic Republic of); Shokrollahi, Ardeshir [Chemistry Department, Yasouj University, Yasouj 75914-353 (Iran, Islamic Republic of); Niknam, Khodabakhsh [Chemistry Department, Persian Gulf University, Bushehr (Iran, Islamic Republic of); Niknam, Ebrahim; Najibi, Asma [Chemistry Department, Yasouj University, Yasouj 75914-353 (Iran, Islamic Republic of); Soylak, Mustafa [Chemistry Department, University of Erciyes, 38039 Kayseri (Turkey)

    2009-09-15

    The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of cadmium(II), lead(II), palladium(II) and silver(I). The analytical procedure involved the formation of understudy metals complex with bis((1H-benzo [d] imidazol-2yl)ethyl) sulfane (BIES), and quantitatively extracted to the phase rich in octylphenoxypolyethoxyethanol (Triton X-114) after centrifugation. Methanol acidified with 1 mol L{sup -1} HNO{sub 3} was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). The concentration of BIES, pH and amount of surfactant (Triton X-114) was optimized. At optimum conditions, the detection limits of (3 sdb/m) of 1.4, 2.8, 1.6 and 1.4 ng mL{sup -1} for Cd{sup 2+}, Pb{sup 2+}, Pd{sup 2+} and Ag{sup +} along with preconcentration factors of 30 and enrichment factors of 48, 39, 32 and 42 for Cd{sup 2+}, Pb{sup 2+}, Pd{sup 2+} and Ag{sup +}, respectively, were obtained. The proposed cloud point extraction has been successfully applied for the determination of metal ions in real samples with complicated matrix such as radiology waste, vegetable, blood and urine samples.

  11. Preconcentrative separation of chromium(III) species from chromium(VI) by cloud point extraction and determination by flame atomic absorption spectrometry

    International Nuclear Information System (INIS)

    We describe a high-throughput technique for the determination of chromium species in water samples by flame atomic absorption spectrometry (FAAS) after preconcentrative separation of Cr(III) species from Cr(VI) by cloud point extraction (CPE) using diethyldithiocarbamate (DDTC) as the chelating agent and the nonionic surfactant Triton X-100 as the extractant. The Cr(III)-DDTC complex is extracted if the temperature is higher than the CPE temperature of Triton X-100, while Cr(VI) remains in the aqueous phase. The Cr(III) in the surfactant phase was analyzed by FAAS, and the concentration of Cr(VI) was calculated by subtraction of Cr(III) from total chromium which was directly determined by FAAS. The effect of pH, concentration of chelating agent, surfactant, and equilibration temperature were investigated. The detection limit for Cr(III) was 0. 08 μg L-1with an enrichment factor of 98, and the relative standard deviation was 1. 2% (n = 3, c = 100 μg L-1). A certified reference material and several water samples were analyzed with satisfactory results. (author)

  12. An evaluation of the bioaccessibility of arsenic in corn and rice samples based on cloud point extraction and hydride generation coupled to atomic fluorescence spectrometry.

    Science.gov (United States)

    Castor, José Martín Rosas; Portugal, Lindomar; Ferrer, Laura; Hinojosa-Reyes, Laura; Guzmán-Mar, Jorge Luis; Hernández-Ramírez, Aracely; Cerdà, Víctor

    2016-08-01

    A simple, inexpensive and rapid method was proposed for the determination of bioaccessible arsenic in corn and rice samples using an in vitro bioaccessibility assay. The method was based on the preconcentration of arsenic by cloud point extraction (CPE) using o,o-diethyldithiophosphate (DDTP) complex, which was generated from an in vitro extract using polyethylene glycol tert-octylphenyl ether (Triton X-114) as a surfactant prior to its detection by atomic fluorescence spectrometry with a hydride generation system (HG-AFS). The CPE method was optimized by a multivariate approach (two-level full factorial and Doehlert designs). A photo-oxidation step of the organic species prior to HG-AFS detection was included for the accurate quantification of the total As. The limit of detection was 1.34μgkg(-1) and 1.90μgkg(-1) for rice and corn samples, respectively. The accuracy of the method was confirmed by analyzing certified reference material ERM BC-211 (rice powder). The corn and rice samples that were analyzed showed a high bioaccessible arsenic content (72-88% and 54-96%, respectively), indicating a potential human health risk. PMID:26988526

  13. Search Cloud

    Science.gov (United States)

    ... this page: https://medlineplus.gov/cloud.html Search Cloud To use the sharing features on this page, ... Top 110 zoster vaccine Share the MedlinePlus search cloud with your users by embedding our search cloud ...

  14. Cloud Point Extraction and Flame Atomic Absorption Spectrometric Determination of Lead, Cadmium and Palladium in Some Food and Biological Samples

    Directory of Open Access Journals (Sweden)

    M. Soylak

    2011-12-01

    Full Text Available The proposed method is based on the complexation of the Pb2+, Cd2+ and Pd2+ ions with 3-(1-(1-H-Indol-3-Yl-3-phenylallyl-1H-indole (IPAI at pH 8.0 in the presence of Triton X-114. The phase separation occured when micellar solution was heated at 55 ◦C. The surfactant-rich phase, diluted to 0.5 mL via 1.0 mol L−1 nitric acid in methanol was directly introduced into the nebulizer of the flame atomic absorption spectrometry (FAAS. Influence of variables such as pH, amount of ligand and Triton X-114, heating time and temperature were evaluated and optimized. The optimized enhancement factors for Pb2+, Cd2+ and Pd2+ ions were 22, 33 and 23, respectively and the detection limit (DLs was between of 1.6–2.6 µgL−1. The relative standard deviation (RSD of each ion was found to be less than 4.6% at 100 µgL−1. In addition, the calibration graphs were linear in the range of 0.01-0.22 μg mL−1 for Cd2+ ion, 0.018-0.26 μg mL−1 for Pb2+ ion and 0.02-0.27 μg mL−1 for Pd2+ ion with the correlation coefficients in the range of 0.995–0.999.

  15. Simultaneous flow injection preconcentration of lead and cadmium using cloud point extraction and determination by atomic absorption spectrometry.

    Science.gov (United States)

    Silva, Edson Luiz; Roldan, Paulo Dos Santos

    2009-01-15

    A flow injection (FI) micelle-mediated separation/preconcentration procedure for the determination of lead and cadmium by flame atomic absorption spectrometry (FAAS) has been proposed. The analytes reacted with 1-(2-thiazolylazo)-2-naphthol (TAN) to form hydrophobic chelates, which were extracted into the micelles of 0.05% (w/v) Triton X-114 in a solution buffered at pH 8.4. In the preconcentration stage, the micellar solution was continuously injected into a flow system with four mini-columns packed with cotton, glass wool, or TNT compresses for phase separation. The analytes-containing micelles were eluted from the mini-columns by a stream of 3molL(-1) HCl solution and the analytes were determined by FAAS. Chemical and flow variables affecting the preconcentration of the analytes were studied. For 15mL of preconcentrated solution, the enhancement factors varied between 15.1 and 20.3, the limits of detection were approximately 4.5 and 0.75microgL(-1) for lead and cadmium, respectively. For a solution containing 100 and 10microgL(-1) of lead and cadmium, respectively, the R.S.D. values varied from 1.6 to 3.2% (n=7). The accuracy of the preconcentration system was evaluated by recovery measurements on spiked water samples. The method was susceptible to matrix effects, but these interferences were minimized by adding barium ions as masking agent in the sample solutions, and recoveries from spiked sample varied in the range of 95.1-107.3%. PMID:18456398

  16. Cloud computing

    OpenAIRE

    Kodera, Lukáš

    2014-01-01

    This thesis deals with cloud computing in Czech Republic, specifically providers of cloud services. In theoretical part there will be explained what is cloud computing, different kinds of cloud computing, virtualization necessary for cloud computing, main concerns about cloud security and also, where cloud is physically stored. In practical part author choose the best solution for company from selected cloud providers in the Czech Republic by using mathematical methods, then author compare th...

  17. [Cloud Point extraction for determination of mercury in Chinese herbal medicine by hydride generation atomic fluorescence spectrometry with optimization using Box-Behnken design].

    Science.gov (United States)

    Wang, Mei; Li, Shan; Zhou, Jian-dong; Xu, Ying; Long, Jun-biao; Yang, Bing-yi

    2014-08-01

    Cloud point extraction (CPE) is proposed as a pre-concentration procedure for the determination of Hg in Chinese herbal medicine samples by hydride generation-atomic fluorescence spectrometry (HG-AFS). Hg2+ was reacted with dithizone to form hydrophobic chelate under the condition of pH. Using Triton X-114, as surfactant, chelate was quantitatively extracted into small volume of the surfactant-rich phase by heating the solution in a water bath for 15 min and centrifuging. Four variables including pH, dithizone concentration, Triton X-114 concentration and equilibrium temperature (T) showed the significant effect on extraction efficiency of total Hg evaluated by single-factor experiment, and Box-Behnken design and response surface method- ology were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum extraction efficiency. The results showed that the binomial was used to fit the response to experimental levels of each variable. ALL linear, quadratic terms of four variables, and interactions between pH and Trion X-114, pH and di- thizone affected the response value(extraction efficiency) significantly at 5% level. The optimum extraction conditions were as follows: pH 5.1, Triton X-114 concentration of 1.16 g x L(-1), dithizone concentration of 4.87 mol x L(-1), and T 58.2 degrees C, the predicted value of fluorescence was 4528.74 under the optimum conditions, and the experimental value had only 2.1% difference with it. Under the conditions, fluorescence was linear to mercury concentration in the range of 1-5 microg x L(-1). The limit of detection obtained was 0.01247 microg x L(-1) with the relative standard deviations (R.S.D.) for six replicate determinations of 1.30%. The proposed method was successfully applied to determination of Hg in morindae Radix, Andrographitis and dried tangerine samples with the recoveries of 95.0%-100.0%. Apparently Box-Behnken design combined with

  18. Search Cloud

    Science.gov (United States)

    ... https://www.nlm.nih.gov/medlineplus/cloud.html Search Cloud To use the sharing features on this page, please enable JavaScript. Share the MedlinePlus search cloud with your users by embedding our search ...

  19. Cloud Governance

    DEFF Research Database (Denmark)

    Berthing, Hans Henrik

    Denne præsentation beskriver fordele og værdier ved anvendelse af Cloud Computing. Endvidere inddrager resultater fra en række internationale analyser fra ISACA om Cloud Computing.......Denne præsentation beskriver fordele og værdier ved anvendelse af Cloud Computing. Endvidere inddrager resultater fra en række internationale analyser fra ISACA om Cloud Computing....

  20. Cloud optics

    CERN Document Server

    Kokhanovsky, A

    2006-01-01

    Clouds affect the climate of the Earth, and they are an important factor in the weather. Therefore, their radiative properties must be understood in great detail. This book summarizes current knowledge on cloud optical properties, for example their ability to absorb, transmit, and reflect light, which depends on the clouds' geometrical and microphysical characteristics such as sizes of droplets and crystals, their shapes, and structures. In addition, problems related to the image transfer through clouds and cloud remote sensing are addressed in this book in great detail. This book can be an im

  1. Cloud Computing

    CERN Document Server

    Antonopoulos, Nick

    2010-01-01

    Cloud computing has recently emerged as a subject of substantial industrial and academic interest, though its meaning and scope is hotly debated. For some researchers, clouds are a natural evolution towards the full commercialisation of grid systems, while others dismiss the term as a mere re-branding of existing pay-per-use technologies. From either perspective, 'cloud' is now the label of choice for accountable pay-per-use access to third party applications and computational resources on a massive scale. Clouds support patterns of less predictable resource use for applications and services a

  2. Cloud Computing

    OpenAIRE

    Mirashe, Shivaji P.; Kalyankar, N. V.

    2010-01-01

    Computing as you know it is about to change, your applications and documents are going to move from the desktop into the cloud. I'm talking about cloud computing, where applications and files are hosted on a "cloud" consisting of thousands of computers and servers, all linked together and accessible via the Internet. With cloud computing, everything you do is now web based instead of being desktop based. You can access all your programs and documents from any computer that's connected to the ...

  3. Managing Clouds in Cloud Platforms

    CERN Document Server

    Ahmat, Kamal A

    2010-01-01

    Managing cloud services is a fundamental challenge in todays virtualized environments. These challenges equally face both providers and consumers of cloud services. The issue becomes even more challenging in virtualized environments that support mobile clouds. Cloud computing platforms such as Amazon EC2 provide customers with flexible, on demand resources at low cost. However, they fail to provide seamless infrastructure management and monitoring capabilities that many customers may need. For instance, Amazon EC2 doesn't fully support cloud services automated discovery and it requires a private set of authentication credentials. Salesforce.com, on the other hand, do not provide monitoring access to their underlying systems. Moreover, these systems fail to provide infrastructure monitoring of heterogenous and legacy systems that don't support agents. In this work, we explore how to build a cloud management system that combines heterogeneous management of virtual resources with comprehensive management of phys...

  4. A Single Atom Thermometer for Ultracold Gases

    CERN Document Server

    Hohmann, Michael; Lausch, Tobias; Mayer, Daniel; Schmidt, Felix; Widera, Artur

    2016-01-01

    We use single or few Cs atoms as thermometer for an ultracold, thermal Rb cloud. Observing the thermometer atoms' thermalization with the cold gas using spatially resolved fluorescence detection, we find an interesting situation, where a fraction of thermometer atoms thermalizes with the cloud while the other fraction remains unaffected. We compare release-recapture measurements of the thermometer atoms to Monte-Carlo simulations while correcting for the non-thermalized fraction, and recover the cold cloud's temperature. The temperatures obtained are verified by independent time-of-flight measurements of the cold cloud's temperature. We also check the reliability of our simulations by first numerically modelling the unperturbed in-trap motion of single atoms in absence of the cold cloud, and second by performing release-recapture thermometry on the cold cloud itself. Our findings pave the way for local temperature probing of quantum systems in non-equilibrium situations.

  5. Cloud Computing

    CERN Document Server

    Mirashe, Shivaji P

    2010-01-01

    Computing as you know it is about to change, your applications and documents are going to move from the desktop into the cloud. I'm talking about cloud computing, where applications and files are hosted on a "cloud" consisting of thousands of computers and servers, all linked together and accessible via the Internet. With cloud computing, everything you do is now web based instead of being desktop based. You can access all your programs and documents from any computer that's connected to the Internet. How will cloud computing change the way you work? For one thing, you're no longer tied to a single computer. You can take your work anywhere because it's always accessible via the web. In addition, cloud computing facilitates group collaboration, as all group members can access the same programs and documents from wherever they happen to be located. Cloud computing might sound far-fetched, but chances are you're already using some cloud applications. If you're using a web-based email program, such as Gmail or Ho...

  6. Cloud Cover

    Science.gov (United States)

    Schaffhauser, Dian

    2012-01-01

    This article features a major statewide initiative in North Carolina that is showing how a consortium model can minimize risks for districts and help them exploit the advantages of cloud computing. Edgecombe County Public Schools in Tarboro, North Carolina, intends to exploit a major cloud initiative being refined in the state and involving every…

  7. Cloud Control

    Science.gov (United States)

    Ramaswami, Rama; Raths, David; Schaffhauser, Dian; Skelly, Jennifer

    2011-01-01

    For many IT shops, the cloud offers an opportunity not only to improve operations but also to align themselves more closely with their schools' strategic goals. The cloud is not a plug-and-play proposition, however--it is a complex, evolving landscape that demands one's full attention. Security, privacy, contracts, and contingency planning are all…

  8. Simultaneous preconcentration of copper and mercury in water samples by cloud point extraction and their determination by inductively coupled plasma atomic emission spectrometry

    Science.gov (United States)

    Shoaee, Hamta; Roshdi, Mina; Khanlarzadeh, Nasibeh; Beiraghi, Asadollah

    2012-12-01

    A cloud-point extraction process coupled to ICP-OES by using 3-nitro benzaldehyde thiosemicarbazone (3-NBT) as complexing agent was developed for the simultaneous preconcentration and determination of copper and mercury in water samples. The variables affecting the complexation and extraction steps were optimized. Under the optimum conditions (i.e. 1.5 × 10-5 mol L-1 ligand, 0.3% (v/v) Triton X-114, 55 °C equilibrium temperature, incubation time of 30 min) the calibration graphs were linear in the range of 5-120 and 10-100 ng mL-1 with enhancement factor of 82.7 and 51.3 for Cu2+ and Hg2+, respectively. The preconcentration factors were 28.6 in both cases and detection limits were obtained 0.48 for Cu and 1.1 ng mL-1 for Hg. The precisions (R.S.D.%) for five replicate determinations at 50 ng mL-1 of copper and mercury were better than 1.8% and 3.2%, respectively. The accuracy of the proposed method is validated by analyzing a certified reference material of water (RTC-QCI-049) with satisfactory results. Finally, the proposed method was utilized successfully for the determination of copper and mercury in surface water (river), tap water and bottled mineral water samples.

  9. Cloud point extraction and flame atomic absorption spectrometric determination of trace lead in freshwater fish%浊点萃取-火焰原子吸收光谱法测定淡水鱼中痕量铅

    Institute of Scientific and Technical Information of China (English)

    王秀峰; 李龙; 张春丽; 林朋; 崔书亚

    2012-01-01

    采用以双硫腙为络合剂、Triton X- 100为表面活性剂的新型浊点萃取体系富集淡水鱼中的痕量铅,并用火焰原子吸收光谱法对其进行测定.探讨了溶液pH、表面活性剂浓度、络合剂用量、平衡温度、平衡时间等对浊点萃取及测定灵敏度的影响,优化了实验条件.在最佳条件下测得铅的检出限为0.090μg/L,校准曲线相关系数为0.9999.该方法已用于淡水鱼中痕量铅的测定.%A new cloud point extraction-flame atomic absorption spectrometric method has been developed to determine trace lead. Dithizone was selected as the complex reagent and Triton X - 100 as the surfactant. Effects of pH, concentrations of surfactant and complex reagent, equilibrium temperature and time on the efficiency and sensitivity of cloud point extraction were investigated. Under optimal conditions, the calibration curve was linear over the concentration range of 0. 1 - 60μg/L with correlation coefficient of 0. 9999 and detection limit of 0. 090 μg/L. The present method was applied to the determination of trace lead in freshwater fish samples with satisfactory results.

  10. Cloud migration

    CERN Document Server

    Höllwarth, Tobias

    2012-01-01

    This book is designed for managers and entrepreneurs, who are considering improving the economics and flexibility of their IT solutions and infrastructures. The book is also for readers who wish to learn more about the Cloud, but do not want to become specialists.This book discusses the technical, legal, fiscal, economic, organisational and environmental aspects of Cloud services. If you are looking for practical advice on vendor selection and certification, as well as real world Cloud project case studies, this is the book to consult.It is the result of a highly cooper

  11. Cloud Computing

    CERN Document Server

    Baun, Christian; Nimis, Jens; Tai, Stefan

    2011-01-01

    Cloud computing is a buzz-word in today's information technology (IT) that nobody can escape. But what is really behind it? There are many interpretations of this term, but no standardized or even uniform definition. Instead, as a result of the multi-faceted viewpoints and the diverse interests expressed by the various stakeholders, cloud computing is perceived as a rather fuzzy concept. With this book, the authors deliver an overview of cloud computing architecture, services, and applications. Their aim is to bring readers up to date on this technology and thus to provide a common basis for d

  12. Microtraps and Atom Chips: Toolboxes for Cold Atom Physics

    OpenAIRE

    Feenstra, L.; Andersson, L. M.; Schmiedmayer, J.

    2003-01-01

    Magnetic microtraps and Atom Chips are safe, small-scale, reliable and flexible tools to prepare ultra-cold and degenerate atom clouds as sources for various atom-optical experiments. We present an overview of the possibilities of the devices and indicate how a microtrap can be used to prepare and launch a Bose-Einstein condensate for use in an atom clock or an interferometer.

  13. Cloud Computing

    DEFF Research Database (Denmark)

    Krogh, Simon

    2013-01-01

    with technological changes, the paradigmatic pendulum has swung between increased centralization on one side and a focus on distributed computing that pushes IT power out to end users on the other. With the introduction of outsourcing and cloud computing, centralization in large data centers is again dominating...... the IT scene. In line with the views presented by Nicolas Carr in 2003 (Carr, 2003), it is a popular assumption that cloud computing will be the next utility (like water, electricity and gas) (Buyya, Yeo, Venugopal, Broberg, & Brandic, 2009). However, this assumption disregards the fact that most IT production......), for instance, in establishing and maintaining trust between the involved parties (Sabherwal, 1999). So far, research in cloud computing has neglected this perspective and focused entirely on aspects relating to technology, economy, security and legal questions. While the core technologies of cloud computing (e...

  14. Cloud Computing

    OpenAIRE

    Bhavana Gupta

    2012-01-01

    Cloud computing is such a type of computing environment, where business owners outsource their computing needs including application software services to a third party and when they need to use the computing power or employees need to use the application resources like database, emails etc., they access the resources via Internet. Cloud computing the use of computing resources (hardware and software) that are delivered as a service over a (typically the Internet).

  15. Realization of an 85Rb Atomic Fountain

    International Nuclear Information System (INIS)

    An atomic fountain with 85Rb cold atoms is reported. A series of time-of-flight signals is obtained, and the measured temperature of the cold atomic cloud is about 2.4 μK. It will have potential new applications in the precise measurement of fundamental constants and the proof of the Einstein's equivalence principle. (atomic and molecular physics)

  16. Cloud point extraction for determination of lead in blood samples of children, using different ligands prior to analysis by flame atomic absorption spectrometry: A multivariate study

    International Nuclear Information System (INIS)

    Highlights: → Trace levels of lead in blood samples of healthy children and with different kidney disorders → Pre-concentration of Pb+2 in acid digested blood samples after chelating with two complexing reagents. → Multivariate technique was used for screening of significant factors that influence the CPE of Pb+2 → The level of Pb+2 in diseased children was significantly higher than referents of same age group. - Abstract: The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of lead (Pb2+) from digested blood samples after simultaneous complexation with ammonium pyrrolidinedithiocarbamate (APDC) and diethyldithiocarbamate (DDTC) separately. The complexed analyte was quantitatively extracted with octylphenoxypolyethoxyethanol (Triton X-114). The multivariate strategy was applied to estimate the optimum values of experimental factors. Acidic ethanol was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometer (FAAS). The detection limit value of Pb2+ for the preconcentration of 10 mL of acid digested blood sample was 1.14 μg L-1. The accuracy of the proposed methods was assessed by analyzing certified reference material (whole blood). Under the optimized conditions of both CPE methods, 10 mL of Pb2+ standards (10 μg L-1) complexed with APDC and DDTC, permitted the enhancement factors of 56 and 42, respectively. The proposed method was used for determination of Pb2+ in blood samples of children with kidney disorders and healthy controls.

  17. Cloud point extraction for determination of lead in blood samples of children, using different ligands prior to analysis by flame atomic absorption spectrometry: A multivariate study

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Faheem, E-mail: shah_ceac@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Kazi, Tasneem Gul, E-mail: tgkazi@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Afridi, Hassan Imran, E-mail: hassanimranafridi@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Naeemullah, E-mail: khannaeemullah@ymail.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan); Arain, Muhammad Balal, E-mail: bilal_ku2004@yahoo.com [Department of Chemistry, University of Science and Technology, Bannu, KPK (Pakistan); Baig, Jameel Ahmed, E-mail: jab_mughal@yahoo.com [National Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro 76080 (Pakistan)

    2011-09-15

    Highlights: {yields} Trace levels of lead in blood samples of healthy children and with different kidney disorders {yields} Pre-concentration of Pb{sup +2} in acid digested blood samples after chelating with two complexing reagents. {yields} Multivariate technique was used for screening of significant factors that influence the CPE of Pb{sup +2} {yields} The level of Pb{sup +2} in diseased children was significantly higher than referents of same age group. - Abstract: The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of lead (Pb{sup 2+}) from digested blood samples after simultaneous complexation with ammonium pyrrolidinedithiocarbamate (APDC) and diethyldithiocarbamate (DDTC) separately. The complexed analyte was quantitatively extracted with octylphenoxypolyethoxyethanol (Triton X-114). The multivariate strategy was applied to estimate the optimum values of experimental factors. Acidic ethanol was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometer (FAAS). The detection limit value of Pb{sup 2+} for the preconcentration of 10 mL of acid digested blood sample was 1.14 {mu}g L{sup -1}. The accuracy of the proposed methods was assessed by analyzing certified reference material (whole blood). Under the optimized conditions of both CPE methods, 10 mL of Pb{sup 2+} standards (10 {mu}g L{sup -1}) complexed with APDC and DDTC, permitted the enhancement factors of 56 and 42, respectively. The proposed method was used for determination of Pb{sup 2+} in blood samples of children with kidney disorders and healthy controls.

  18. Determination of nickel in blood and serum samples of oropharyngeal cancer patients consumed smokeless tobacco products by cloud point extraction coupled with flame atomic absorption spectrometry.

    Science.gov (United States)

    Arain, Sadaf Sadia; Kazi, Tasneem Gul; Arain, Jamshed Bashir; Afridi, Hassan Imran; Kazi, Atif Gul; Nasreen, Syeda; Brahman, Kapil Dev

    2014-10-01

    Oropharyngeal cancer is a significant public health issue in the world. The incidence of oropharyngeal cancer has been increased among people who have habit of chewing smokeless tobacco (SLT) in Pakistan. The aim of present study was to evaluate the concentration of nickel (Ni) in biological samples (whole blood, serum) of oral (n = 95) and pharyngeal (n = 84) male cancer patients. For comparison purposes, the biological samples of healthy age-matched referents (n = 150), who consumed and did not consumed SLT products, were also analyzed for Ni levels. As the Ni level is very low in biological samples, a preconcentration procedure has been developed, prior to analysis of analyte by flame atomic absorption spectrometry (FAAS). The Ni in acid-digested biological samples was complexed with ammonium pyrrolidinedithio carbamate (APDC), and a resulted complex was extracted in a surfactant Triton X-114. Acidic ethanol was added to the surfactant-rich phase prior to its analysis by FAAS. The chemical variables, such as pH, amounts of reagents (APDC, Triton X-114), temperature, incubation time, and sample volume were optimized. The resulted data indicated that concentration of Ni was higher in blood and serum samples of cancer patients as compared to that of referents who have or have not consumed different SLT products (p = 0.012-0.001). It was also observed that healthy referents who consumed SLT products have two to threefold higher levels of Ni in both biological samples as compared to those who were not chewing SLT products (p < 0.01). PMID:24920259

  19. Cooperative phenomena in superconducting atom-chips

    Energy Technology Data Exchange (ETDEWEB)

    Fuchs, Sebastian; Kubala, Bjoern; Ankerhold, Joachim [Institut fuer Theoretische Physik, Universitaet Ulm, Albert-Einstein-Allee 11, 89069 Ulm (Germany)

    2013-07-01

    We theoretically investigate the physics of hybrid quantum systems, where a cloud of cold atoms is coupled to superconducting microstructures, so called superconducting atom-chips. Coherent enhancement, due to the large number of atoms in the cloud, opens a path to the study of strong coupling effects, like superradiance/Dicke-physics in a decohering environment. A structured environment can be designed by embedding a Cooper pair box within the cavity. Moreover, in such a system the transfer of quantum information between the atomic cloud and the superconducting solid state system can be studied.

  20. Cooperative phenomena in superconducting atom-chips

    International Nuclear Information System (INIS)

    We theoretically investigate the physics of hybrid quantum systems, where a cloud of cold atoms is coupled to superconducting microstructures, so called superconducting atom-chips. Coherent enhancement, due to the large number of atoms in the cloud, opens a path to the study of strong coupling effects, like superradiance/Dicke-physics in a decohering environment. A structured environment can be designed by embedding a Cooper pair box within the cavity. Moreover, in such a system the transfer of quantum information between the atomic cloud and the superconducting solid state system can be studied.

  1. Test of the quantumness of atom-atom correlations in a bosonic gas

    OpenAIRE

    Ivanov, D.; Wallentowitz, S.

    2006-01-01

    It is shown how the quantumness of atom-atom correlations in a trapped bosonic gas can be made observable. Application of continuous feedback control of the center of mass of the atomic cloud is shown to generate oscillations of the spatial extension of the cloud, whose amplitude can be directly used as a characterization of atom-atom correlations. Feedback parameters can be chosen such that the violation of a Schwarz inequality for atom-atom correlations can be tested at noise levels much hi...

  2. Mobile Clouds

    DEFF Research Database (Denmark)

    Fitzek, Frank; Katz, Marcos

    A mobile cloud is a cooperative arrangement of dynamically connected communication nodes sharing opportunistic resources. In this book, authors provide a comprehensive and motivating overview of this rapidly emerging technology. The book explores how distributed resources can be shared by mobile...... examples of mobile clouds applications, based on both existing commercial initiatives as well as proof-of-concept test-beds. Visions and prospects are also discussed, paving the way for further development. As mobile networks and social networks become more and more reliant on each other, the concept of...

  3. CLOUD COMPUTING

    Directory of Open Access Journals (Sweden)

    Dr. Vinod Kumar

    2013-01-01

    Full Text Available Cloud computing is the delivery of computing as a service rather than a product, whereby shared resources, software, and information are provided to computers and other devices as a utility (like the electricity grid over a network (typically the internet. Cloud computing provides computation, software, data access, and storage services that do not require end-user knowledge of the physical location and configuration of the system that delivers the services. Parallel to this concept can be drawn with the electricity grid, wherein end-users consume power without needing to understand the component devices or infrastructure required to provide the service.

  4. Self-organized criticality in boson clouds around black holes

    OpenAIRE

    Mocanu, Gabriela-Raluca; Grumiller, Daniel

    2012-01-01

    Boson clouds around black holes exhibit interesting physical phenomena through the Penrose process of superradiance, leading to black hole spin-down. Axionic clouds are of particular interest, since the axion Compton wavelength could be comparable to the Schwarzschild radius, leading to the formation of "gravitational atoms" with a black hole nucleus. These clouds collapse under certain conditions, leading to a "Bosenova". We model the dynamics of such unstable boson clouds by a simple cellul...

  5. Cloud Computing

    OpenAIRE

    Bhavana Gupta

    2012-01-01

    Cloud computing is such a type of computing environment, where business owners outsource their computing needs including application software services to a third party and when they need to use the computing power or employees need to use the application resources like database, emails etc., they access the resources via Internet

  6. Rapid Molecular Cloud and Star Formation: Mechanisms and Movies

    CERN Document Server

    Heitsch, Fabian

    2008-01-01

    We demonstrate that the observationally inferred rapid onset of star formation after parental molecular clouds have assembled can be achieved by flow-driven cloud formation of atomic gas, using our previous three-dimensional numerical simulations. We post-process these simulations to approximate CO formation, which allows us to investigate the times at which CO becomes abundant relative to the onset of cloud collapse. We find that global gravity in a finite cloud has two crucial effects on cloud evolution. (a) Lateral collapse (perpendicular to the flows sweeping up the cloud) leads to rapidly increasing column densities above the accumulation from the one-dimensional flow. This in turn allows fast formation of CO, allowing the molecular cloud to ``appear'' rapidly. (b) Global gravity is required to drive the dense gas to the high pressures necessary to form solar-mass cores, in support of recent analytical models of cloud fragmentation. While the clouds still appear ``supersonically turbulent'', this turbule...

  7. Cloud point extraction and flame atomic absorption spectrometry determination fo trace lead in urine%浊点萃取-火焰原子吸收光谱法测定人尿液中的痕量铅

    Institute of Scientific and Technical Information of China (English)

    杜军良; 杨双; 胡杨; 王秀峰

    2014-01-01

    A method for the determination of Pb in urine by flame atomic absorption spectrometry with cloud point extraction was es-tablished. Dithizone-acetone was selected as the complex reagent and TritonX-100 as the surfactant. Effects of pH concentrations of surfactant and complex reagent equilibrium temperature and time on the efficiency and sensitivity for clound point extraction were investigated. Under optimal conditions the detection limit was 0. 06 μg·L-1(n=11)with linear over the concentration range of 0~1. 00 μg·mL-1 ,and values of recovery were in the range of 96. 7% ~101%. The present method was applied to the determination of trace lead in urine samples with satisfactory results.%以双硫腙作为络合剂、聚乙二醇辛基苯基醚( TritonX-100)为非离子表面活性剂,建立浊点萃取-火焰原子吸收光谱测定尿液中痕量铅的方法。探讨了络合剂用量、平衡时间、pH值、TritonX-100用量、冰浴时间等因素对萃取效率的影响。结果表明:该方法对铅的最大富集倍数约为40倍,检出限为0.06μg·L-1( n=11)。回收率在96.7%~101%,线性范围为0~1.00μg·mL-1。利用该方法测定尿液中痕量铅的含量,结果令人满意。

  8. Cloud management and security

    CERN Document Server

    Abbadi, Imad M

    2014-01-01

    Written by an expert with over 15 years' experience in the field, this book establishes the foundations of Cloud computing, building an in-depth and diverse understanding of the technologies behind Cloud computing. In this book, the author begins with an introduction to Cloud computing, presenting fundamental concepts such as analyzing Cloud definitions, Cloud evolution, Cloud services, Cloud deployment types and highlighting the main challenges. Following on from the introduction, the book is divided into three parts: Cloud management, Cloud security, and practical examples. Part one presents the main components constituting the Cloud and federated Cloud infrastructure(e.g., interactions and deployment), discusses management platforms (resources and services), identifies and analyzes the main properties of the Cloud infrastructure, and presents Cloud automated management services: virtual and application resource management services. Part two analyzes the problem of establishing trustworthy Cloud, discuss...

  9. Surrogate cloud fields with measured cloud properties

    CERN Document Server

    Venema, V; Simmer, C; Venema, Victor; Crewell, Susanne; Simmer, Clemens

    2003-01-01

    This paper describes two new methods to generate 2D and 3D cloud fields based on 1D and 2D ground based profiler meas-urements. These cloud fields share desired statistical properties with real cloud fields. As they, however, are similar but not the same as real clouds, we call them surrogate clouds. One important advantage of the new methods is that the amplitude distribution of cloud liquid water is also exactly determined by the measurement: The surrogate clouds made with the classi-cal methods such as the Fourier method and the Bounded Cascade method are Gaussian and 'log-normal-like', respectively. Our first new method iteratively creates a time series with a measured amplitude distribution and power spectrum. Our sec-ond method uses an evolutionary search algorithm to generate cloud fields with practically arbitrary constraints. These clouds will be used to study the relation between radiation and cloud structure.

  10. Soft Clouding

    DEFF Research Database (Denmark)

    Søndergaard, Morten; Markussen, Thomas; Wetton, Barnabas;

    2012-01-01

    Soft Clouding is a blended concept, which describes the aim of a collaborative and transdisciplinary project. The concept is a metaphor implying a blend of cognitive, embodied interaction and semantic web. Furthermore, it is a metaphor describing our attempt of curating a new semantics of sound...... competencies brought together in one transdisciplinary process of curating a semantics of sound: Technological, Humanistic /Curatorial, and Design / Action-based practice....

  11. Demonstration of a cold atom beam splitter on atom chip

    Science.gov (United States)

    Jiang, Xiaojun; Li, Xiaolin; Zhang, Haichao; Wang, Yuzhu

    2016-08-01

    We report an experimental demonstration of a new scheme to split cold atoms on an atom chip. The atom chip consists of a U-wire and a Z-wire. The cold atom cloud is initially loaded and prepared in the Z-trap, which is split into two separate parts by switching on the current of the U-wire. The two separate atom clouds have a distance more than one millimeter apart from each other and show almost symmetrical profiles, corresponding to about a 50/50 splitting ratio. Project supported by the State Key Basic Research Program of China (Grant No. 2011CB921504) and the National Natural Science Foundation of China (Grant No. 91536107).

  12. Essentials of cloud computing

    CERN Document Server

    Chandrasekaran, K

    2014-01-01

    ForewordPrefaceComputing ParadigmsLearning ObjectivesPreambleHigh-Performance ComputingParallel ComputingDistributed ComputingCluster ComputingGrid ComputingCloud ComputingBiocomputingMobile ComputingQuantum ComputingOptical ComputingNanocomputingNetwork ComputingSummaryReview PointsReview QuestionsFurther ReadingCloud Computing FundamentalsLearning ObjectivesPreambleMotivation for Cloud ComputingThe Need for Cloud ComputingDefining Cloud ComputingNIST Definition of Cloud ComputingCloud Computing Is a ServiceCloud Computing Is a Platform5-4-3 Principles of Cloud computingFive Essential Charact

  13. Instrument measures cloud cover

    Science.gov (United States)

    Laue, E. G.

    1981-01-01

    Eight solar sensing cells comprise inexpensive monitoring instrument. Four cells always track Sun while other four face sky and clouds. On overcast day, cloud-irradiance sensors generate as much short-circuit current as Sun sensor cells. As clouds disappear, output of cloud sensors decreases. Ratio of two sensor type outputs determines fractional cloud cover.

  14. Estimating Cloud Cover

    Science.gov (United States)

    Moseley, Christine

    2007-01-01

    The purpose of this activity was to help students understand the percentage of cloud cover and make more accurate cloud cover observations. Students estimated the percentage of cloud cover represented by simulated clouds and assigned a cloud cover classification to those simulations. (Contains 2 notes and 3 tables.)

  15. Cloud Computing, Tieto Cloud Server Model

    OpenAIRE

    Suikkanen, Saara

    2013-01-01

    The purpose of this study is to find out what is cloud computing. To be able to make wise decisions when moving to cloud or considering it, companies need to understand what cloud is consists of. Which model suits best to they company, what should be taken into account before moving to cloud, what is the cloud broker role and also SWOT analysis of cloud? To be able to answer customer requirements and business demands, IT companies should develop and produce new service models. IT house T...

  16. Cloud droplet measurement methods

    International Nuclear Information System (INIS)

    All important techniques to measure cloud and fog droplets are mentioned in this compendium. It especially refers to those authors who established and developed measurement methods for cloud droplets and to those whose papers contained cloud droplet size distributions. (orig.)

  17. Blue skies for CLOUD

    CERN Multimedia

    2006-01-01

    Through the recently approved CLOUD experiment, CERN will soon be contributing to climate research. Tests are being performed on the first prototype of CLOUD, an experiment designed to assess cosmic radiation influence on cloud formation.

  18. Cloud Computing (4)

    Institute of Scientific and Technical Information of China (English)

    Wang Bai; Xu Liutong

    2010-01-01

    @@ 8 Case Study Cloud computing is still a new phenomenon. Although many IT giants are developing their own cloud computing infrastructures,platforms, software, and services, few have really succeeded in becoming cloud computing providers.

  19. Silicon Photonics Cloud (SiCloud)

    DEFF Research Database (Denmark)

    DeVore, P. T. S.; Jiang, Y.; Lynch, M.;

    2015-01-01

    Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths.......Silicon Photonics Cloud (SiCloud.org) is the first silicon photonics interactive web tool. Here we report new features of this tool including mode propagation parameters and mode distribution galleries for user specified waveguide dimensions and wavelengths....

  20. Coherent backscattering of light by cold atoms: theory meets experiment

    OpenAIRE

    Labeyrie, Guillaume; Delande, Dominique; Mueller, Cord A.; Miniatura, Christian; Kaiser, Robin

    2002-01-01

    Coherent backscattering (CBS) of quasi-resonant light by cold atoms presents some specific features due to the internal structure of the atomic scatterers. We present the first quantitative comparison between the experimentally observed CBS cones and Monte-Carlo calculations which take into account the shape of the atomic cloud as well as the internal atomic structure.

  1. Coherent backscattering of light by cold atoms: theory meets experiment

    International Nuclear Information System (INIS)

    Coherent backscattering (CBS) of quasi-resonant light by cold atoms presents some specific features due to the internal structure of the atomic scatterers. We present the first quantitative comparison between the experimentally observed CBS cones and Monte Carlo calculations which take into account the shape of the atomic cloud as well as the internal atomic structure. (authors)

  2. Cloud storage for dummies

    CERN Document Server

    Xu, Linda; Loughlin, Tanya

    2010-01-01

    Understand cloud computing and save your organization time and money! Cloud computing is taking IT by storm, but what is it and what are the benefits to your organization? Hitachi Data Systems' Cloud Storage For Dummies provides all the answers, With this book, you discover a clear explanation of cloud storage, and tips for how to choose the right type of cloud storage for your organization's needs. You also find out how cloud storage can free up valuable IT resources, saving time and money. Cloud Storage For Dummies presents useful information on setting up a

  3. Cloud Computing (1)

    Institute of Scientific and Technical Information of China (English)

    Wang Bai; Xu Liutong

    2010-01-01

    @@ Editor's Desk: Cloud computing is a topic of intense interest in the Internet field. Major IT giants have launched their own cloud computing products. This four-part lecture series will discuss cloud computing technology in the following aspects: The first part provides a brief description of the origin and characteristics of cloud computing from the users view of point; the other parts introduce typical applications of cloud computing, technically analyze the specific content within the cloud, its components, architecture and computational paradigm, compare cloud computing to other distributed computing technologies, and discuss its successful cases, commercial models, related technical and economic issues, and development trends.

  4. Cloud Computing (2)

    Institute of Scientific and Technical Information of China (English)

    Wang Bai; Xu Liutong

    2010-01-01

    @@ Editor's Desk: Cloud computing is a topic of intense interest in the Internet field. Major IT giants have launched their own cloud computing products. This four-part lecture series discusses cloud computing technology in the following aspects: The first part provided a brief description of the origin and characteristics of cloud computing from the users view of point; the other parts introduce typical applications of cloud computing, technically analyze the specific content within the cloud, its components, architecture and computational paradigm, compare cloud computing to other distributed computing technologies, and discuss its successful cases, commercial models, related technical and economic issues, and development trends.

  5. Cloud Robotics Platforms

    OpenAIRE

    Busra Koken

    2015-01-01

    Cloud robotics is a rapidly evolving field that allows robots to offload computation-intensive and storage-intensive jobs into the cloud. Robots are limited in terms of computational capacity, memory and storage. Cloud provides unlimited computation power, memory, storage and especially collaboration opportunity. Cloud-enabled robots are divided into two categories as standalone and networked robots. This article surveys cloud robotic platforms, standalone and networked robotic works such as ...

  6. Multiparty Cloud Computation

    OpenAIRE

    Zheng, Qingji; Zhang, Xinwen

    2012-01-01

    With the increasing popularity of the cloud, clients oursource their data to clouds in order to take advantage of unlimited virtualized storage space and the low management cost. Such trend prompts the privately oursourcing computation, called \\emph{multiparty cloud computation} (\\MCC): Given $k$ clients storing their data in the cloud, how can they perform the joint functionality by contributing their private data as inputs, and making use of cloud's powerful computation capability. Namely, ...

  7. Cloud Robotics Platforms

    Directory of Open Access Journals (Sweden)

    Busra Koken

    2015-01-01

    Full Text Available Cloud robotics is a rapidly evolving field that allows robots to offload computation-intensive and storage-intensive jobs into the cloud. Robots are limited in terms of computational capacity, memory and storage. Cloud provides unlimited computation power, memory, storage and especially collaboration opportunity. Cloud-enabled robots are divided into two categories as standalone and networked robots. This article surveys cloud robotic platforms, standalone and networked robotic works such as grasping, simultaneous localization and mapping (SLAM and monitoring.

  8. The CLOUD experiment

    CERN Multimedia

    Maximilien Brice

    2006-01-01

    The Cosmics Leaving Outdoor Droplets (CLOUD) experiment as shown by Jasper Kirkby (spokesperson). Kirkby shows a sketch to illustrate the possible link between galactic cosmic rays and cloud formations. The CLOUD experiment uses beams from the PS accelerator at CERN to simulate the effect of cosmic rays on cloud formations in the Earth's atmosphere. It is thought that cosmic ray intensity is linked to the amount of low cloud cover due to the formation of aerosols, which induce condensation.

  9. Cloud Computing (3)

    Institute of Scientific and Technical Information of China (English)

    Wang Bai; Xu Liutong

    2010-01-01

    @@ Editor's Desk: In the preceding two parts of this series, several aspects of cloud computing-including definition, classification, characteristics, typical applications, and service levels-were discussed. This part continues with a discussion of Cloud Computing Oopen Architecture and Market-Oriented Cloud. A comparison is made between cloud computing and other distributed computing technologies, and Google's cloud platform is analyzed to determine how distributed computing is implemented in its particular model.

  10. Relationship between cloud radiative forcing, cloud fraction and cloud albedo, and new surface-based approach for determining cloud albedo

    OpenAIRE

    Liu, Y; Wu, W.; Jensen, M. P.; T. Toto

    2011-01-01

    This paper focuses on three interconnected topics: (1) quantitative relationship between surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo; (2) surfaced-based approach for measuring cloud albedo; (3) multiscale (diurnal, annual and inter-annual) variations and covariations of surface shortwave cloud radiative forcing, cloud fraction, and cloud albedo. An analytical expression is first derived to quantify the relationship between cloud radiative forcing, cloud fractio...

  11. Silicon chemistry in interstellar clouds

    Energy Technology Data Exchange (ETDEWEB)

    Langer, W.D.; Glassgold, A.E. (AT T Bell Laboratories, Murray Hill, NJ (USA) New York Univ., NY (USA))

    1990-03-01

    A new model of interstellar silicon chemistry is presented that explains the lack of SiO detections in cold clouds and contains an exponential temperature dependence for the SiO abundance. A key aspect of the model is the sensitivity of SiO production by neutral silicon reactions to density and temperature, which arises from the dependence of the rate coefficients on the population of the excited fine-structure levels of the silicon atom. As part of the explanation of the lack of SiO detections at low temperatures and densities, the model also emphasizes the small efficiencies of the production routes and the correspondingly long times needed to reach equilibrium. Measurements of the abundance of SiO, in conjunction with theory, can provide information on the physical properties of interstellar clouds such as the abundance of oxygen bearing molecules and the depletion of interstellar silicon. 38 refs.

  12. OH+ in Diffuse Molecular Clouds

    CERN Document Server

    Porras, A J; Welty, D E; Ritchey, A M

    2013-01-01

    Near ultraviolet observations of OH+ and OH in diffuse molecular clouds reveal a preference for different environments. The dominant absorption feature in OH+ arises from a main component seen in CH+ (that with the highest CH+/CH column density ratio), while OH follows CN absorption. This distinction provides new constraints on OH chemistry in these clouds. Since CH+ detections favor low-density gas with small fractions of molecular hydrogen, this must be true for OH+ as well, confirming OH+ and H2O+ observations with the Herschel Space Telescope. Our observed correspondence indicates that the cosmic ray ionization rate derived from these measurements pertains to mainly atomic gas. The association of OH absorption with gas rich in CN is attributed to the need for high enough density and molecular fraction before detectable amounts are seen. Thus, while OH+ leads to OH production, chemical arguments suggest that their abundances are controlled by different sets of conditions and that they coexist with differen...

  13. Cloud CCN feedback

    International Nuclear Information System (INIS)

    Cloud microphysics affects cloud albedo precipitation efficiency and the extent of cloud feedback in response to global warming. Compared to other cloud parameters, microphysics is unique in its large range of variability and the fact that much of the variability is anthropogenic. Probably the most important determinant of cloud microphysics is the spectra of cloud condensation nuclei (CCN) which display considerable variability and have a large anthropogenic component. When analyzed in combination three field observation projects display the interrelationship between CCN and cloud microphysics. CCN were measured with the Desert Research Institute (DRI) instantaneous CCN spectrometer. Cloud microphysical measurements were obtained with the National Center for Atmospheric Research Lockheed Electra. Since CCN and cloud microphysics each affect the other a positive feedback mechanism can result

  14. Cloud Databases: A Paradigm Shift in Databases

    Directory of Open Access Journals (Sweden)

    Indu Arora

    2012-07-01

    Full Text Available Relational databases ruled the Information Technology (IT industry for almost 40 years. But last few years have seen sea changes in the way IT is being used and viewed. Stand alone applications have been replaced with web-based applications, dedicated servers with multiple distributed servers and dedicated storage with network storage. Cloud computing has become a reality due to its lesser cost, scalability and pay-as-you-go model. It is one of the biggest changes in IT after the rise of World Wide Web. Cloud databases such as Big Table, Sherpa and SimpleDB are becoming popular. They address the limitations of existing relational databases related to scalability, ease of use and dynamic provisioning. Cloud databases are mainly used for data-intensive applications such as data warehousing, data mining and business intelligence. These applications are read-intensive, scalable and elastic in nature. Transactional data management applications such as banking, airline reservation, online e-commerce and supply chain management applications are write-intensive. Databases supporting such applications require ACID (Atomicity, Consistency, Isolation and Durability properties, but these databases are difficult to deploy in the cloud. The goal of this paper is to review the state of the art in the cloud databases and various architectures. It further assesses the challenges to develop cloud databases that meet the user requirements and discusses popularly used Cloud databases.

  15. Trusted Cloud Platform for Cloud Infrastructure

    OpenAIRE

    Punit Gupta; Deepika Agrawal

    2013-01-01

    Reliability and trust Models are used to enhance secure , reliable scheduling , load balancing and QoS in cloud and Distributed environment. Trust models that are being used in Distributed and Grid environment, does not qualify cloud computing environment requirements. Since the parameters that have being taken into consideration in these trust models, does not fit in the cloud Infrastructure As A Service, a suitable trust model is proposed based on the existing model that is suitable for tru...

  16. Diffusion and deposition of the Schooner clouds

    International Nuclear Information System (INIS)

    Schooner was a 31-kt nuclear cratering experiment done as part of the U.S. Atomic Energy Commission's Plowshare Program. Detonation was at 0800 PST on December 8, 1968 at the Nevada Test Site. The resulting cloud had ceased its dynamic growth by about H+4 min. Two distinct parts, a base surge and a main cloud, were evident. Thereafter, further cloud growth was by diffusion and fallout as the cloud moved downwind. Aircraft sampling of the cloud at H+12.5 min revealed that the main cloud part contained about 10 times as much radioactivity as the base surge part. Later aircraft data, local fallout field measurements, and airborne particle size data indicate that the H+12.5-min cloud burdens, primarily the tungsten isotopes, were depleted by a factor of about 2, due to fallout, over the next few hours. The remaining airborne cloud burdens for each cloud were used as input to diffusion calculations. Calculated main cloud center concentrations using observed cloud sizes, cloud burdens, and meteorology agree with measurements to better than a factor of 2 over 1 1/2 days. These postshot calculations and data are about a factor of 3 higher than calculations done preshot. Base surge calculations are consistent with available data to within about a factor of 4, but the data needed to perform as complete an analysis as was done for the main cloud do not exist. Fallout, as distinguished from deposition of nonfalling debris, was important to a distance of about 500 km for the main cloud and to a distance of about 100 km for the base surge. At distances closer to ground zero, diffusion calculations under-predicted ground level concentration and deposition, but an isotopically scaled external gross gamma fallout calculation was within about a factor of 3 of the data. At larger distances downwind for the base surge, ground level exposure rate calculations and deposition for a variety of nuclides agree to within about a factor of 3 of measurements. (author)

  17. Secure cloud computing

    CERN Document Server

    Jajodia, Sushil; Samarati, Pierangela; Singhal, Anoop; Swarup, Vipin; Wang, Cliff

    2014-01-01

    This book presents a range of cloud computing security challenges and promising solution paths. The first two chapters focus on practical considerations of cloud computing. In Chapter 1, Chandramouli, Iorga, and Chokani describe the evolution of cloud computing and the current state of practice, followed by the challenges of cryptographic key management in the cloud. In Chapter 2, Chen and Sion present a dollar cost model of cloud computing and explore the economic viability of cloud computing with and without security mechanisms involving cryptographic mechanisms. The next two chapters addres

  18. Hybrid cloud for dummies

    CERN Document Server

    Hurwitz, Judith; Halper, Fern; Kirsch, Dan

    2012-01-01

    Understand the cloud and implement a cloud strategy for your business Cloud computing enables companies to save money by leasing storage space and accessing technology services through the Internet instead of buying and maintaining equipment and support services. Because it has its own unique set of challenges, cloud computing requires careful explanation. This easy-to-follow guide shows IT managers and support staff just what cloud computing is, how to deliver and manage cloud computing services, how to choose a service provider, and how to go about implementation. It also covers security and

  19. Two-component model of the interaction of an interstellar cloud with surrounding hot plasma

    OpenAIRE

    Provornikova, E. A.; Izmodenov, V. V.; Lallement, R.

    2011-01-01

    We present a two-component gasdynamic model of an interstellar cloud embedded in a hot plasma. It is assumed that the cloud consists of atomic hydrogen gas, interstellar plasma is quasineutral. Hydrogen atoms and plasma protons interact through a charge exchange process. Magnetic felds and radiative processes are ignored in the model. The influence of heat conduction within plasma on the interaction between a cloud and plasma is studied. We consider the extreme case and assume that hot plasma...

  20. Atom Chips

    CERN Document Server

    Folman, R; Cassettari, D; Hessmo, B; Maier, T; Schmiedmayer, J; Folman, Ron; Krüger, Peter; Cassettari, Donatella; Hessmo, Björn; Maier, Thomas

    1999-01-01

    Atoms can be trapped and guided using nano-fabricated wires on surfaces, achieving the scales required by quantum information proposals. These Atom Chips form the basis for robust and widespread applications of cold atoms ranging from atom optics to fundamental questions in mesoscopic physics, and possibly quantum information systems.

  1. Moving towards Cloud Security

    Directory of Open Access Journals (Sweden)

    Edit Szilvia Rubóczki

    2015-01-01

    Full Text Available Cloud computing hosts and delivers many different services via Internet. There are a lot of reasons why people opt for using cloud resources. Cloud development is increasing fast while a lot of related services drop behind, for example the mass awareness of cloud security. However the new generation upload videos and pictures without reason to a cloud storage, but only few know about data privacy, data management and the proprietary of stored data in the cloud. In an enterprise environment the users have to know the rule of cloud usage, however they have little knowledge about traditional IT security. It is important to measure the level of their knowledge, and evolve the training system to develop the security awareness. The article proves the importance of suggesting new metrics and algorithms for measuring security awareness of corporate users and employees to include the requirements of emerging cloud security.

  2. Genomics With Cloud Computing

    OpenAIRE

    Sukhamrit Kaur; Sandeep Kaur

    2015-01-01

    Abstract Genomics is study of genome which provides large amount of data for which large storage and computation power is needed. These issues are solved by cloud computing that provides various cloud platforms for genomics. These platforms provides many services to user like easy access to data easy sharing and transfer providing storage in hundreds of terabytes more computational power. Some cloud platforms are Google genomics DNAnexus and Globus genomics. Various features of cloud computin...

  3. Analysis on Cloud Computing

    OpenAIRE

    S.PATHRO; Venkatesh, D.; K.J.SRIHARSHA

    2013-01-01

    Cloud storage enables users to remotelystore their data and enjoy the on-demand high quality cloud applications without the burden of local hardware and software management. Though the benefits are clear, such a service is also relinquishing users’ physical possession of their outsourced data, which inevitably poses new security risks towards the correctness of the data in cloud. In order to address this new problem and further achieve a secure and dependable cloud storage service, we propose...

  4. Cloud computing strategies

    CERN Document Server

    Chorafas, Dimitris N

    2011-01-01

    A guide to managing cloud projects, Cloud Computing Strategies provides the understanding required to evaluate the technology and determine how it can be best applied to improve business and enhance your overall corporate strategy. Based on extensive research, it examines the opportunities and challenges that loom in the cloud. It explains exactly what cloud computing is, what it has to offer, and calls attention to the important issues management needs to consider before passing the point of no return regarding financial commitments.

  5. Cloud Computing: a Prologue

    OpenAIRE

    Ullah, Sultan; Xuefeng, Zheng

    2013-01-01

    An emerging internet based super computing model is represented by cloud computing. Cloud computing is the convergence and evolution of several concepts from virtualization, distributed storage, grid, and automation management to enable a more flexible approach for deploying and scaling applications. However, cloud computing moves the application software and databases to the large data centers, where the management of the data and services may not be fully trustworthy. The concept of cloud c...

  6. Virtualizace a cloud computing

    OpenAIRE

    Davídek, Michal

    2013-01-01

    The aim of this diploma thesis are current computing technologies known as Cloud computing. Main goal is to compare technologies and Cloud services provided by companies nowadays. During this thesis will be proven or not, that usage of Cloud technologies can save company finance due to optimized data management, effective backups, license administration or management of computing resources for single applications/users. Final part will present recommendations for Cloud Service providers or en...

  7. Cloud Oriented Applications

    OpenAIRE

    Razvan DINA

    2009-01-01

    Cloud computing is a paradigm that incorporates the concept of software as a service. The current cloud computing architecture involves the existence of data centers that are able to provide services to the clients located all over the world. The major players in field of the cloud computing are Google, Microsoft, Amazon, Yahoo, and some traditional hardware producers like HP, IBM, Intel.

  8. Introduction to Cloud Computing

    OpenAIRE

    Conway, Gerry

    2011-01-01

    This paper describes cloud computing, its main characteristics and the models that are currently used for both deployment and delivery. It examines the benefits and business issues with using the cloud, and how they can be addressed. It describes some of the early adapters of cloud computing, together with their experiences.

  9. On CLOUD nine

    CERN Multimedia

    2009-01-01

    The team from the CLOUD experiment - the world’s first experiment using a high-energy particle accelerator to study the climate - were on cloud nine after the arrival of their new three-metre diameter cloud chamber. This marks the end of three years’ R&D and design, and the start of preparations for data taking later this year.

  10. Cloud Computing Explained

    Science.gov (United States)

    Metz, Rosalyn

    2010-01-01

    While many talk about the cloud, few actually understand it. Three organizations' definitions come to the forefront when defining the cloud: Gartner, Forrester, and the National Institutes of Standards and Technology (NIST). Although both Gartner and Forrester provide definitions of cloud computing, the NIST definition is concise and uses…

  11. On clocks and clouds

    Directory of Open Access Journals (Sweden)

    M. K. Witte

    2013-09-01

    Full Text Available Cumulus clouds exhibit a life cycle that consists of: (a the growth phase (increasing size, most notably in the vertical direction; (b the mature phase (growth ceases; any precipitation that develops is strongest during this period; and (c the dissipation phase (cloud dissipates because of precipitation and/or entrainment; no more dynamical support. Although radar can track clouds over time and give some sense of the age of a cloud, most aircraft in situ measurements lack temporal context. We use large eddy simulations of trade wind cumulus cloud fields from cases during the Barbados Oceanographic and Meteorological Experiment (BOMEX and Rain In Cumulus over the Ocean (RICO campaigns to demonstrate a potential cumulus cloud "clock". We find that the volume-averaged total water mixing ratio rt is a useful cloud clock for the 12 clouds studied. A cloud's initial rt is set by the subcloud mixed-layer mean rt and decreases monotonically from the initial value due primarily to entrainment. The clock is insensitive to aerosol loading, environmental sounding and extrinsic cloud properties such as lifetime and volume. In some cases (more commonly for larger clouds, multiple pulses of buoyancy occur, which complicate the cumulus clock by replenishing rt. The clock is most effectively used to classify clouds by life phase.

  12. Dephasing dynamics of Rydberg atom spin waves

    CERN Document Server

    Bariani, F; Kennedy, T A B

    2012-01-01

    A theory of Rydberg atom interactions is used to derive analytical forms for the spin wave pair correlation function in laser-excited cold-atom vapors. This function controls the quantum statistics of light emission from dense, inhomogeneous clouds of cold atoms of various spatial dimensionalities. The results yield distinctive scaling behaviors on the microsecond timescale, including generalized exponential decay. A detailed comparison is presented with a recent experiment on a cigar-shaped atomic ensemble [Y. Dudin and A. Kuzmich, Science 336, 887 (2012)], in which Rb atoms are excited to a set of Rydberg levels.

  13. Carbon Isotope Chemistry in Molecular Clouds

    Science.gov (United States)

    Robertson, Amy N.; Willacy, Karen

    2012-01-01

    Few details of carbon isotope chemistry are known, especially the chemical processes that occur in astronomical environments like molecular clouds. Observational evidence shows that the C-12/C-13 abundance ratios vary due to the location of the C-13 atom within the molecular structure. The different abundances are a result of the diverse formation pathways that can occur. Modeling can be used to explore the production pathways of carbon molecules in an effort to understand and explain the chemical evolution of molecular clouds.

  14. OH+ IN DIFFUSE MOLECULAR CLOUDS

    International Nuclear Information System (INIS)

    Near ultraviolet observations of OH+ and OH in diffuse molecular clouds reveal a preference for different environments. The dominant absorption feature in OH+ arises from a main component seen in CH+ (that with the highest CH+/CH column density ratio), while OH follows CN absorption. This distinction provides new constraints on OH chemistry in these clouds. Since CH+ detections favor low-density gas with small fractions of molecular hydrogen, this must be true for OH+ as well, confirming OH+ and H2O+ observations with the Herschel Space Telescope. Our observed correspondence indicates that the cosmic ray ionization rate derived from these measurements pertains to mainly atomic gas. The association of OH absorption with gas rich in CN is attributed to the need for a high enough density and molecular fraction before detectable amounts are seen. Thus, while OH+ leads to OH production, chemical arguments suggest that their abundances are controlled by different sets of conditions and that they coexist with different sets of observed species. Of particular note is that non-thermal chemistry appears to play a limited role in the synthesis of OH in diffuse molecular clouds

  15. Single-impulse magnetic focusing of launched cold atoms

    International Nuclear Information System (INIS)

    We have theoretically investigated the focusing of a launched cloud of cold atoms. Time-dependent spatially-varying magnetic fields are used to impart impulses leading to a three-dimensional focus of the launched cloud. We discuss possible coil arrangements for a new focusing regime: isotropic 3D focusing of atoms with a single-impulse magnetic lens. We investigate focusing aberrations and find that, for typical experimental parameters, the widely used assumption of a purely harmonic lens is often inaccurate. The baseball lens offers the best possibility for isotropically focusing a cloud of weak-field-seeking atoms in 3D

  16. Single-impulse magnetic focusing of launched cold atoms

    Science.gov (United States)

    Pritchard, Matthew J.; Arnold, Aidan S.; Smith, David A.; Hughes, Ifan G.

    2004-11-01

    We have theoretically investigated the focusing of a launched cloud of cold atoms. Time-dependent spatially-varying magnetic fields are used to impart impulses leading to a three-dimensional focus of the launched cloud. We discuss possible coil arrangements for a new focusing regime: isotropic 3D focusing of atoms with a single-impulse magnetic lens. We investigate focusing aberrations and find that, for typical experimental parameters, the widely used assumption of a purely harmonic lens is often inaccurate. The baseball lens offers the best possibility for isotropically focusing a cloud of weak-field-seeking atoms in 3D.

  17. Single-impulse magnetic focusing of launched cold atoms

    CERN Document Server

    Pritchard, M J; Smith, D A; Hughes, I G; Pritchard, Matthew J; Arnold, Aidan S; Smith, David A; Hughes, Ifan G

    2004-01-01

    We have theoretically investigated the focusing of a launched cloud of cold atoms. Time-dependent spatially-varying magnetic fields are used to impart impulses leading to a three-dimensional focus of the launched cloud. We discuss possible coil arrangements for a new focusing regime: isotropic 3D focusing of atoms with a single-impulse magnetic lens. We investigate focusing aberrations and find that, for typical experimental parameters, the widely used assumption of a purely harmonic lens is often inaccurate. The baseball lens offers the best possibility for isotropically focusing a cloud of weak-field-seeking atoms in 3D.

  18. Cloud Computing Bible

    CERN Document Server

    Sosinsky, Barrie

    2010-01-01

    The complete reference guide to the hot technology of cloud computingIts potential for lowering IT costs makes cloud computing a major force for both IT vendors and users; it is expected to gain momentum rapidly with the launch of Office Web Apps later this year. Because cloud computing involves various technologies, protocols, platforms, and infrastructure elements, this comprehensive reference is just what you need if you'll be using or implementing cloud computing.Cloud computing offers significant cost savings by eliminating upfront expenses for hardware and software; its growing popularit

  19. The Magellanic clouds

    International Nuclear Information System (INIS)

    As the two galaxies nearest to our own, the Magellanic Clouds hold a special place in studies of the extragalactic distance scale, of stellar evolution and the structure of galaxies. In recent years, results from the South African Astronomical Observatory (SAAO) and elsewhere have shown that it is possible to begin understanding the three dimensional structure of the Clouds. Studies of Magellanic Cloud Cepheids have continued, both to investigate the three-dimensional structure of the Clouds and to learn more about Cepheids and their use as extragalactic distance indicators. Other research undertaken at SAAO includes studies on Nova LMC 1988 no 2 and red variables in the Magellanic Clouds

  20. Corona Discharge in Clouds

    Science.gov (United States)

    Sin'kevich, A. A.; Dovgalyuk, Yu. A.

    2014-04-01

    We present a review of the results of theoretical studies and laboratory modeling of corona discharge initiation in clouds. The influence of corona discharges on the evolution of the cloud microstructure and electrification is analyzed. It is shown that corona discharges are initiated when large-size hydrometeors approach each other, whereas in some cases, corona discharges from crystals, ice pellets, and hailstones can appear. The corona discharges lead to significant air ionization, charging of cloud particles, and separation of charges in clouds and initiate streamers and lightnings. The influence of corona discharges on changes in the phase composition of clouds is analyzed.

  1. Atomic energy

    CERN Multimedia

    1996-01-01

    Interviews following the 1991 co-operation Agreement between the Department of Atomic Energy (DAE) of the Government of India and the European Organization for Nuclear Research (CERN) concerning the participation in the Large Hadron Collider Project (LHC) . With Chidambaram, R, Chairman, Atomic Energy Commission and Secretary, Department of Atomic Energy, Department of Atomic Energy (DAE) of the Government of India and Professor Llewellyn-Smith, Christopher H, Director-General, CERN.

  2. Atom chips

    CERN Document Server

    Reichel, Jakob

    2010-01-01

    This book provides a stimulating and multifaceted picture of a rapidly developing field. The first part reviews fundamentals of atom chip research in tutorial style, while subsequent parts focus on the topics of atom-surface interaction, coherence on atom chips, and possible future directions of atom chip research. The articles are written by leading researchers in the field in their characteristic and individual styles.

  3. THE EVOLUTION OF GAS CLOUDS FALLING IN THE MAGNETIZED GALACTIC HALO: HIGH-VELOCITY CLOUDS (HVCs) ORIGINATED IN THE GALACTIC FOUNTAIN

    International Nuclear Information System (INIS)

    In the Galactic fountain scenario, supernovae and/or stellar winds propel material into the Galactic halo. As the material cools, it condenses into clouds. By using FLASH three-dimensional magnetohydrodynamic simulations, we model and study the dynamical evolution of these gas clouds after they form and begin to fall toward the Galactic plane. In our simulations, we assume that the gas clouds form at a height of z = 5 kpc above the Galactic midplane, then begin to fall from rest. We investigate how the cloud's evolution, dynamics, and interaction with the interstellar medium (ISM) are affected by the initial mass of the cloud. We find that clouds with sufficiently large initial densities (n ≥ 0.1 H atoms cm-3) accelerate sufficiently and maintain sufficiently large column densities as to be observed and identified as high-velocity clouds (HVCs) even if the ISM is weakly magnetized (1.3 μG). However, the ISM can provide noticeable resistance to the motion of a low-density cloud (n ≤ 0.01 H atoms cm-3) thus making it more probable that a low-density cloud will attain the speed of an intermediate-velocity cloud rather than the speed of an HVC. We also investigate the effects of various possible magnetic field configurations. As expected, the ISM's resistance is greatest when the magnetic field is strong and perpendicular to the motion of the cloud. The trajectory of the cloud is guided by the magnetic field lines in cases where the magnetic field is oriented diagonal to the Galactic plane. The model cloud simulations show that the interactions between the cloud and the ISM can be understood via analogy to the shock tube problem which involves shock and rarefaction waves. We also discuss accelerated ambient gas, streamers of material ablated from the clouds, and the cloud's evolution from a sphere-shaped to a disk- or cigar-shaped object.

  4. Atomic polarizabilities

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, M. S. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Mitroy, J. [School of Engineering, Charles Darwin University, Darwin NT 0909 (Australia); Clark, Charles W. [Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899-8410 (United States); Kozlov, M. G. [Petersburg Nuclear Physics Institute, Gatchina 188300 (Russian Federation)

    2015-01-22

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed.

  5. Atomic Physics

    CERN Document Server

    Foot, Christopher J

    2007-01-01

    This text will thoroughly update the existing literature on atomic physics. Intended to accompany an advanced undergraduate course in atomic physics, the book will lead the students up to the latest advances and the applications to Bose-Einstein Condensation of atoms, matter-wave inter-ferometry and quantum computing with trapped ions. The elementary atomic physics covered in the early chapters should be accessible to undergraduates when they are first introduced to the subject. To complement. the usual quantum mechanical treatment of atomic structure the book strongly emphasizes the experimen

  6. Atomic polarizabilities

    International Nuclear Information System (INIS)

    The atomic dipole polarizability governs the first-order response of an atom to an applied electric field. Atomic polarization phenomena impinge upon a number of areas and processes in physics and have been the subject of considerable interest and heightened importance in recent years. In this paper, we will summarize some of the recent applications of atomic polarizability studies. A summary of results for polarizabilities of noble gases, monovalent, and divalent atoms is given. The development of the CI+all-order method that combines configuration interaction and linearized coupled-cluster approaches is discussed

  7. Cloud Computing Governance Lifecycle

    Directory of Open Access Journals (Sweden)

    Soňa Karkošková

    2016-06-01

    Full Text Available Externally provisioned cloud services enable flexible and on-demand sourcing of IT resources. Cloud computing introduces new challenges such as need of business process redefinition, establishment of specialized governance and management, organizational structures and relationships with external providers and managing new types of risk arising from dependency on external providers. There is a general consensus that cloud computing in addition to challenges brings many benefits but it is unclear how to achieve them. Cloud computing governance helps to create business value through obtain benefits from use of cloud computing services while optimizing investment and risk. Challenge, which organizations are facing in relation to governing of cloud services, is how to design and implement cloud computing governance to gain expected benefits. This paper aims to provide guidance on implementation activities of proposed Cloud computing governance lifecycle from cloud consumer perspective. Proposed model is based on SOA Governance Framework and consists of lifecycle for implementation and continuous improvement of cloud computing governance model.

  8. Secure Cloud Architecture

    Directory of Open Access Journals (Sweden)

    Kashif Munir

    2013-02-01

    Full Text Available Cloud computing is set of resources and services offered through the Internet. Cloud services are delivered from data centers located throughout the world. Cloud computing facilitates its consumers by providing virtual resources via internet. The biggest challenge in cloud computing is the security and privacy problems caused by its multi-tenancy nature and the outsourcing of infrastructure, sensitive data and critical applications. Enterprises are rapidly adopting cloud services for their businesses, measures need to be developed so that organizations can be assured of security in their businesses and can choose a suitable vendor for their computing needs. Cloud computing depends on the internet as a medium for users to access the required services at any time on pay-per-use pattern. However this technology is still in its initial stages of development, as it suffers from threats and vulnerabilities that prevent the users from trusting it. Various malicious activitiesfrom illegal users have threatened this technology such as data misuse, inflexible access control and limited monitoring. The occurrence of these threats may result into damaging or illegal access of critical and confidential data of users. In this paper we identify the most vulnerable security threats/attacks in cloud computing, which will enable both end users and vendors to know a bout the k ey security threats associated with cloud computing and propose relevant solution directives to strengthen security in the Cloud environment. We also propose secure cloud architecture for organizations to strengthen the security.

  9. Atom interferometry

    International Nuclear Information System (INIS)

    We will first present a development of the fundamental principles of atom interferometers. Next we will discuss a few of the various methods now available to split and recombine atomic De Broglie waves, with special emphasis on atom interferometers based on optical pulses. We will also be particularly concerned with high precision interferometers with long measurement times such those made with atomic fountains. The application of atom interferometry to the measurement of the acceleration due to gravity will be detailed. We will also develop the atom interferometry based on adiabatic transfer and we will apply it to the measurement of the photon recoil in the case of the Doppler shift of an atomic resonance caused by the momentum recoil from an absorbed photon. Finally the outlook of future developments will be given. (A.C.)

  10. Spontaneous decay of an atom excited in a dense and disordered atomic ensemble: quantum microscopic approach

    CERN Document Server

    Kuraptsev, A S

    2016-01-01

    On the basis of general theoretical results developed previously in [I. M. Sokolov et al., J. Exp. Theor. Phys. 112, 246 (2011)], we analyze spontaneous decay of a single atom inside cold atomic clouds under conditions when the averaged interatomic separation is less or comparable with the wavelength of quasi resonant radiation. Beyond the decay dynamics we analyze shifts of resonance as well as distortion of the spectral shape of the atomic transition.

  11. Energy Aware Clouds

    Science.gov (United States)

    Orgerie, Anne-Cécile; de Assunção, Marcos Dias; Lefèvre, Laurent

    Cloud infrastructures are increasingly becoming essential components for providing Internet services. By benefiting from economies of scale, Clouds can efficiently manage and offer a virtually unlimited number of resources and can minimize the costs incurred by organizations when providing Internet services. However, as Cloud providers often rely on large data centres to sustain their business and offer the resources that users need, the energy consumed by Cloud infrastructures has become a key environmental and economical concern. This chapter presents an overview of techniques that can improve the energy efficiency of Cloud infrastructures. We propose a framework termed as Green Open Cloud, which uses energy efficient solutions for virtualized environments; the framework is validated on a reference scenario.

  12. Cloud Robotics Model

    Directory of Open Access Journals (Sweden)

    Gyula Mester

    2015-01-01

    Full Text Available Cloud Robotics was born from the merger of service robotics and cloud technologies. It allows robots to benefit from the powerful computational, storage, and communications resources of modern data centres. Cloud robotics allows robots to take advantage of the rapid increase in data transfer rates to offload tasks without hard real time requirements. Cloud Robotics has rapidly gained momentum with initiatives by companies such as Google, Willow Garage and Gostai as well as more than a dozen active research projects around the world. The presentation summarizes the main idea, the definition, the cloud model composed of essential characteristics, service models and deployment models, planning task execution and beyond. Finally some cloud robotics projects are discussed.

  13. Encyclopedia of cloud computing

    CERN Document Server

    Bojanova, Irena

    2016-01-01

    The Encyclopedia of Cloud Computing provides IT professionals, educators, researchers and students with a compendium of cloud computing knowledge. Authored by a spectrum of subject matter experts in industry and academia, this unique publication, in a single volume, covers a wide range of cloud computing topics, including technological trends and developments, research opportunities, best practices, standards, and cloud adoption. Providing multiple perspectives, it also addresses questions that stakeholders might have in the context of development, operation, management, and use of clouds. Furthermore, it examines cloud computing's impact now and in the future. The encyclopedia presents 56 chapters logically organized into 10 sections. Each chapter covers a major topic/area with cross-references to other chapters and contains tables, illustrations, side-bars as appropriate. Furthermore, each chapter presents its summary at the beginning and backend material, references and additional resources for further i...

  14. CLOUD COMPUTING SECURITY

    Directory of Open Access Journals (Sweden)

    DANISH JAMIL,

    2011-04-01

    Full Text Available It is no secret that cloud computing is becoming more and more popular today and is ever increasing inpopularity with large companies as they share valuable resources in a cost effective way. Due to this increasingdemand for more clouds there is an ever growing threat of security becoming a major issue. This paper shalllook at ways in which security threats can be a danger to cloud computing and how they can be avoided.

  15. Ammonia Clouds on Jupiter

    Science.gov (United States)

    2007-01-01

    [figure removed for brevity, see original site] Click on the image for movie of Ammonia Ice Clouds on Jupiter In this movie, put together from false-color images taken by the New Horizons Ralph instrument as the spacecraft flew past Jupiter in early 2007, show ammonia clouds (appearing as bright blue areas) as they form and disperse over five successive Jupiter 'days.' Scientists noted how the larger cloud travels along with a small, local deep hole.

  16. Developing Secure Cloud Applications

    OpenAIRE

    Rak, Massimiliano; Ficco, Massimo; Battista, Ermanno; Casola, Valentina; Mazzocca, Nicola

    2014-01-01

    Today the main limit to Cloud adoption is related to the perception of a security loss the users have. Indeed, the existing solutions to provide security are mainly focused on Cloud service provider prospective in order to securely integrate frameworks and Infrastructures as a Services in a Cloud datacenter. Customer could not monitor and evaluate the security mechanisms enforced by service provider. Service Level Agreements mainly focus on performance related terms and no guarantees are ...

  17. The Kondo Screening Cloud

    OpenAIRE

    Affleck, Ian

    2001-01-01

    Renormalization group theory of the Kondo effect predicts that an impurity spin is screened by a conduction electron spread over a large distance of order >.1 to 1 micron. This review has the following sections: 1. The Kondo effect and the screening cloud, 2. Non-observation of the Kondo cloud in conventional experiments, 3. Kondo effect in transmission through a quantum dot, 4. Observing the screening cloud in persistent current experiments, 5. Side-coupled quantum dot, 6. Conclusions

  18. CLOUD Experiment - How it works -

    CERN Document Server

    Jasper Kirkby

    2016-01-01

    A brief tour of the CLOUD experiment at CERN, and its scientific aims. CLOUD uses a special cloud chamber to study the possible link between galactic cosmic rays and cloud formation. The results should contribute much to our fundamental understanding of aerosols and clouds, and their affect on climate.

  19. Considerations for Cloud Security Operations

    OpenAIRE

    Cusick, James

    2016-01-01

    Information Security in Cloud Computing environments is explored. Cloud Computing is presented, security needs are discussed, and mitigation approaches are listed. Topics covered include Information Security, Cloud Computing, Private Cloud, Public Cloud, SaaS, PaaS, IaaS, ISO 27001, OWASP, Secure SDLC.

  20. The Magellanic Clouds

    International Nuclear Information System (INIS)

    It is known that mira variables in the Large Magellanic Cloud (LMC) show an infrared period-luminosity relation. The refinement of the period-luminosity relation of cepheids and miras has been advanced at the South African Astronomical Observatory (SAAO) during 1986. Studies undertaken at SAAO have included: the mira period-luminosity relation in the LMC; the young cluster NGC 1866 and its cepheids; cepheids in the Magellanic Clouds; RR Lyraes in Magellanic Cloud clusters; carbon and s-type stars in the Magellanic Clouds, and old LMC clusters. 2 figs

  1. The California Molecular Cloud

    OpenAIRE

    Lada, Charles J.; Lombardi, Marco; Alves, Joao F.

    2009-01-01

    We present an analysis of wide-field infrared extinction maps of a region in Perseus just north of the Taurus-Auriga dark cloud complex. From this analysis we have identified a massive, nearby, but previously unrecognized, giant molecular cloud (GMC). From comparison of foreground star counts with Galactic models we derive a distance of 450 +/- 23 parsecs to the cloud. At this distance the cloud extends over roughly 80 pc and has a mass of approximately 10^5 solar masses, rivaling the Orion (...

  2. Absorption imaging of a single atom

    OpenAIRE

    Streed, E. W.; Jechow, A.; Norton, B. G.; Kielpinski, D.

    2012-01-01

    Absorption imaging has played a key role in the advancement of science from van Leeuwenhoek's discovery of red blood cells to modern observations of dust clouds in stellar nebulas and Bose-Einstein condensates. Here we show the first absorption imaging of a single atom isolated in vacuum. The optical properties of atoms are thoroughly understood, so a single atom is an ideal system for testing the limits of absorption imaging. A single atomic ion was confined in an RF Paul trap and the absorp...

  3. Cold atoms in videotape micro-traps

    Science.gov (United States)

    Sinclair, C. D. J.; Retter, J. A.; Curtis, E. A.; Hall, B. V.; Llorente Garcia, I.; Eriksson, S.; Sauer, B. E.; Hinds, E. A.

    2005-08-01

    We describe an array of microscopic atom traps formed by a pattern of magnetisation on a piece of videotape. We describe the way in which cold atoms are loaded into one of these micro-traps and how the trapped atom cloud is used to explore the properties of the trap. Evaporative cooling in the micro-trap down to a temperature of 1~μK allows us to probe the smoothness of the trapping potential and reveals some inhomogeneity produced by the magnetic film. We discuss future prospects for atom chips based on microscopic permanent-magnet structures.

  4. Cold atoms in videotape micro-traps

    CERN Document Server

    Sinclair, C D J; Curtis, E A; Hall, B V; Garcia, I L; Eriksson, S; Sauer, B E; Hinds, E A

    2005-01-01

    We describe an array of microscopic atom traps formed by a pattern of magnetisation on a piece of videotape. We describe the way in which cold atoms are loaded into one of these micro-traps and how the trapped atom cloud is used to explore the properties of the trap. Evaporative cooling in the micro-trap down to a temperature of 1 microkelvin allows us to probe the smoothness of the trapping potential and reveals some inhomogeneity produced by the magnetic film. We discuss future prospects for atom chips based on microscopic permanent-magnet structures.

  5. Rapid Formation of Molecular Clouds and Stars in the Solar Neighborhood

    CERN Document Server

    Hartmann, L; Bergin, E A; Hartmann, Lee; Ballesteros-Paredes, Javier; Bergin, Edwin A.

    2001-01-01

    Observations of both star-forming regions and young, gas-free stellar associations indicate that most nearby molecular clouds form stars only over a short time span before dispersal; large-scale flows in the diffuse interstellar medium have the potential for forming clouds sufficiently rapidly, and for producing stellar populations with ages much less than the lateral crossing times of their host molecular clouds. We identify four important factors for understanding rapid star formation and short cloud lifetimes. First, much of the accumulation and dispersal of clouds near the solar circle might occur in the atomic phase; only the high-density portion of a cloud's lifecycle is spent in the molecular phase, thus helping to limit molecular cloud ``lifetimes''. Second, once a cloud achieves a high enough column density to form $\\h2$ and CO, gravitational forces become larger than typical interstellar pressure forces; thus star formation can follow rapidly upon molecular gas formation and turbulent dissipation in...

  6. Non-destructive Faraday imaging of dynamically controlled ultracold atoms

    CERN Document Server

    Gajdacz, Miroslav; Mørch, Troels; Hilliard, Andrew J; Arlt, Jan; Sherson, Jacob F

    2013-01-01

    We introduce an easily implementable method for non-destructive measurements of ultracold atomic clouds based on dark field imaging of spatially resolved Faraday rotation. The dependence on laser detuning, atomic density and temperature is characterized in a detailed comparison with theory. Due to low destructiveness, the same cloud can be imaged up to 2000 times. The technique is applied to avoid the effect of shot-to-shot fluctuations in atom number calibration, to demonstrate single-run vector magnetic field imaging and single-run spatial imaging of the system's dynamic behavior. This paves the way towards quantum state engineering using feedback control of ultracold atoms.

  7. A cloud storage overlay to aggregate heterogeneous cloud services

    OpenAIRE

    Machado, Guilherme Sperb; Bocek, Thomas; Ammann, Michael; Stiller, Burkhard

    2013-01-01

    Many Cloud services provide generic (e.g., Amazon S3 or Dropbox) or data-specific Cloud storage (e.g., Google Picasa or SoundCloud). Although both Cloud storage service types have the data storage in common, they present heterogeneous characteristics: different interfaces, accounting and charging schemes, privacy and security levels, functionality and, among the data-specific Cloud storage services, different data type restrictions. This paper proposes PiCsMu (Platform-independent Cloud Stora...

  8. Review of Cloud Computing and existing Frameworks for Cloud adoption

    OpenAIRE

    Chang, Victor; Walters, Robert John; Wills, Gary

    2014-01-01

    This paper presents a selected review for Cloud Computing and explains the benefits and risks of adopting Cloud Computing in a business environment. Although all the risks identified may be associated with two major Cloud adoption challenges, a framework is required to support organisations as they begin to use Cloud and minimise risks of Cloud adoption. Eleven Cloud Computing frameworks are investigated and a comparison of their strengths and limitations is made; the result of the comparison...

  9. Schroedinger atom

    International Nuclear Information System (INIS)

    Features of an electrodynamical interpretation suggested by Schroedinger for the wave function are discribed. According to this conception electron charges are continuously distributed all over the volume of an atomic system. The proof is given that classical electrodynamics keeps its action inside atom. Schroedinger's atom has been shown to be the only model in which electrones do not lose their energy for emission when they move around nucleus. A significance of the distributed electron charge self-field is estimated. Practical applications of this conception have been noted including the new trend in quantum electrodynamics. Experimental and theoretical corroborations of the atom model with a continuous electron charge are adduced

  10. Atomic physics

    International Nuclear Information System (INIS)

    Research activities in atomic physics at Lawrence Berkeley Laboratory during 1976 are described. Topics covered include: experiments on stored ions; test for parity violation in neutral weak currents; energy conservation and astrophysics; atomic absorption spectroscopy, atomic and molecular detectors; theoretical studies of quantum electrodynamics and high-z ions; atomic beam magnetic resonance; radiative decay from the 23Po,2 levels of helium-like argon; quenching of the metastable 2S/sub 1/2/ state of hydrogen-like argon in an external electric field; and lifetime of the 23Po level of helium-like krypton

  11. Electron impact ionization of Io's sodium emission cloud

    Science.gov (United States)

    Carlson, R. W.; Matson, D. L.; Johnson, T. V.

    1975-01-01

    The geometry of the sodium cloud associated with Io (Jupiter I) indicates that the lifetime of the neutral sodium atoms is an order of magnitude less than the photoionization lifetime. We suggest that ionization by thermal plasma electrons in the Jovian magnetosphere is the dominant Na loss process. Using plasma densities deduced from Pioneer 10 measurements, the lifetime and density distributions are calculated for Na and other species which may be present in the cloud around Io. Electron ionization of Na is found to be an order of magnitude faster than photoionization, in agreement with the lifetime deduced from Na cloud observations.

  12. Cold atom microtraps above a videotape surface

    International Nuclear Information System (INIS)

    Much progress has been made in the last two years towards miniaturizing magnetic traps for cold atoms. This will enable manipulation of coherent samples of atoms, such as Bose-Einstein condensates, or single atoms, on the scale of the atomic de Broglie wavelength. This thesis concerns an array of microscopic magnetic potentials formed close to the surface of magnetized videotape, when a uniform bias field is applied. The recorded magnetization is a 100 μm sine wave, which covers a 12.5mm x 22mm piece of commercial videotape. This videotape is glued flat onto a thin glass substrate and is gold coated by evaporation so that atoms can be trapped close to the surface in a mirror-MOT. An 'atom chip' has been developed, incorporating the videotape and current-carrying wires located below the magnetized surface. A single wire and bias field create a magnetic tube potential, oriented parallel with the microtraps and with a quadrupole radial field. This allows the mirror-MOT to be compressed and distorted in order to match it to a magnetic trap formed by the same wire and bias field. Increasing the bias field and reducing the wire current further compresses the atom cloud and brings it closer to the surface, until it is fully transferred to the videotape microtraps. The atom cloud is confined axially by the potential produced by two parallel current-carrying wires with 8mm separation. This is the first demonstration of loading cold atoms into microtraps formed above a permanently magnetized surface. It is interesting to compare the properties of such traps with those formed above current carrying wires. We present measurements of the lifetimes of trapped atom clouds as a function of height and trap frequency. These results suggest that this technology may prove to be a promising basis for future experiments with atom chips. (author)

  13. VMware vCloud security

    CERN Document Server

    Sarkar, Prasenjit

    2013-01-01

    VMware vCloud Security provides the reader with in depth knowledge and practical exercises sufficient to implement a secured private cloud using VMware vCloud Director and vCloud Networking and Security.This book is primarily for technical professionals with system administration and security administration skills with significant VMware vCloud experience who want to learn about advanced concepts of vCloud security and compliance.

  14. Research on cloud computing solutions

    OpenAIRE

    Liudvikas Kaklauskas; Vaida Zdanytė

    2015-01-01

    Cloud computing can be defined as a new style of computing in which dynamically scala-ble and often virtualized resources are provided as a services over the Internet. Advantages of the cloud computing technology include cost savings, high availability, and easy scalability. Voas and Zhang adapted six phases of computing paradigms, from dummy termi-nals/mainframes, to PCs, networking computing, to grid and cloud computing. There are four types of cloud computing: public cloud, private cloud, ...

  15. Taxonomy of cloud computing services

    OpenAIRE

    Hoefer, C.N.; Karagiannis, G.

    2010-01-01

    Cloud computing is a highly discussed topic, and many big players of the software industry are entering the development of cloud services. Several companies want to explore the possibilities and benefits of cloud computing, but with the amount of cloud computing services increasing quickly, the need for a taxonomy framework rises. This paper describes the available cloud computing services, and proposes a treestructured taxonomy based on their characteristics, to easily classify cloud computi...

  16. Clouds over Open Ocean

    Science.gov (United States)

    1981-01-01

    The heavy concentration of these cirrocumulus and nimbostratus clouds over open ocean - location unknown, indicate that a heavy downpouring of rain is occuring on the Earth's surface below. Towering anvils, seen rising high above the base cloud cover and casting long shadows, also indicate high winds and possible tornado activity.

  17. Cloud speed sensor

    Directory of Open Access Journals (Sweden)

    V. Fung

    2013-10-01

    Full Text Available Changing cloud cover is a major source of solar radiation variability and poses challenges for the integration of solar energy. A compact and economical system that measures cloud motion vectors to estimate power plant ramp rates and provide short term solar irradiance forecasts is presented. The Cloud Speed Sensor (CSS is constructed using an array of luminance sensors and high-speed data acquisition to resolve the progression of cloud passages across the sensor footprint. An embedded microcontroller acquires the sensor data and uses a cross-correlation algorithm to determine cloud motion vectors. The CSS was validated against an artificial shading test apparatus, an alternative method of cloud motion detection from ground measured irradiance (Linear Cloud Edge, LCE, and a UC San Diego Sky Imager (USI. The CSS detected artificial shadow directions and speeds to within 15 and 6% accuracy, respectively. The CSS detected (real cloud directions and speeds without average bias and with average weighted root mean square difference of 22° and 1.9 m s−1 when compared to USI and 33° and 1.5 m s−1 when compared to LCE results.

  18. Smoke Above Clouds

    Science.gov (United States)

    Remer, Lorraine A.

    2009-01-01

    Aerosols in the atmosphere alter the radiative balance of the Earth by reflecting or absorbing solar radiation. Spaceborne measurements of clouds and aerosols advected over the southeastern Atlantic Ocean indicate that the greater the cloud cover below the aerosols, the more likely the aerosols are to heat the planet.

  19. On Cloud Nine

    Science.gov (United States)

    McCrea, Bridget; Weil, Marty

    2011-01-01

    Across the U.S., innovative collaboration practices are happening in the cloud: Sixth-graders participate in literary salons. Fourth-graders mentor kindergarteners. And teachers use virtual Post-it notes to advise students as they create their own television shows. In other words, cloud computing is no longer just used to manage administrative…

  20. Cloud Computing Simulation Using CloudSim

    OpenAIRE

    Kumar, Ranjan; Sahoo, G.

    2014-01-01

    As we know that Cloud Computing is a new paradigm in IT. It has many advantages and disadvantages. But in future it will spread in the whole world. Many researches are going on for securing the cloud services. Simulation is the act of imitating or pretending. It is a situation in which a particular set of condition is created artificially in order to study that could exit in reality. We need only a simple Operating System with some memory to startup our Computer. All our resources will be ava...

  1. Atomic physics

    CERN Document Server

    Born, Max

    1989-01-01

    The Nobel Laureate's brilliant exposition of the kinetic theory of gases, elementary particles, the nuclear atom, wave-corpuscles, atomic structure and spectral lines, electron spin and Pauli's principle, quantum statistics, molecular structure and nuclear physics. Over 40 appendices, a bibliography, numerous figures and graphs.

  2. Cloud computing basics

    CERN Document Server

    Srinivasan, S

    2014-01-01

    Cloud Computing Basics covers the main aspects of this fast moving technology so that both practitioners and students will be able to understand cloud computing. The author highlights the key aspects of this technology that a potential user might want to investigate before deciding to adopt this service. This book explains how cloud services can be used to augment existing services such as storage, backup and recovery. Addressing the details on how cloud security works and what the users must be prepared for when they move their data to the cloud. Also this book discusses how businesses could prepare for compliance with the laws as well as industry standards such as the Payment Card Industry.

  3. Cloud Computing Quality

    Directory of Open Access Journals (Sweden)

    Anamaria Şiclovan

    2013-02-01

    Full Text Available

    Cloud computing was and it will be a new way of providing Internet services and computers. This calculation approach is based on many existing services, such as the Internet, grid computing, Web services. Cloud computing as a system aims to provide on demand services more acceptable as price and infrastructure. It is exactly the transition from computer to a service offered to the consumers as a product delivered online. This paper is meant to describe the quality of cloud computing services, analyzing the advantages and characteristics offered by it. It is a theoretical paper.

    Keywords: Cloud computing, QoS, quality of cloud computing

  4. Io's sodium cloud

    Science.gov (United States)

    Goldberg, B. A.; Garneau, G. W.; Lavoie, S. K.

    1984-01-01

    The first two-dimensional images of the source region of Io's neutral sodium cloud have been acquired by ground-based observation. Observed asymmetries in its spatial brightness distribution provide new evidence that the cloud is supplied by sodium that is ejected nonisotropically from Io or its atmosphere. Complementary, high-time-resolution, calibrated image sequences that give the first comprehensive picture of the variations of the fainter regions of the cloud extending more than 100,000 kilometers from Io were also obtained. These data demonstrate that the cloud exhibits a persistent systematic behavior coupled with Io's orbital position, a distinct 'east-west orbital asymmetry', a variety of spatial morphologies, and true temporal changes. The geometric stability of the sodium source is also indicated. Isolation of the cloud's temporal changes constitutes an important milestone toward its utilization as a long-term probe of Io and the inner Jovian magnetosphere.

  5. Prebiotic chemistry in clouds

    Science.gov (United States)

    Oberbeck, Verne R.; Marshall, John; Shen, Thomas

    1991-01-01

    The chemical evolution hypothesis of Woese (1979), according to which prebiotic reactions occurred rapidly in droplets in giant atmospheric reflux columns was criticized by Scherer (1985). This paper proposes a mechanism for prebiotic chemistry in clouds that answers Scherer's concerns and supports Woese's hypothesis. According to this mechanism, rapid prebiotic chemical evolution was facilitated on the primordial earth by cycles of condensation and evaporation of cloud drops containing clay condensation nuclei and nonvolatile monomers. For example, amino acids supplied by, or synthesized during entry of meteorites, comets, and interplanetary dust, would have been scavenged by cloud drops containing clay condensation nuclei and would be polymerized within cloud systems during cycles of condensation, freezing, melting, and evaporation of cloud drops.

  6. SMILES ice cloud products

    Science.gov (United States)

    MilláN, L.; Read, W.; Kasai, Y.; Lambert, A.; Livesey, N.; Mendrok, J.; Sagawa, H.; Sano, T.; Shiotani, M.; Wu, D. L.

    2013-06-01

    Upper tropospheric water vapor and clouds play an important role in Earth's climate, but knowledge of them, in particular diurnal variation in deep convective clouds, is limited. An essential variable to understand them is cloud ice water content. The Japanese Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on board the International Space Station (ISS) samples the atmosphere at different local times allowing the study of diurnal variability of atmospheric parameters. We describe a new ice cloud data set consisting of partial Ice Water Path and Ice Water Content. Preliminary comparisons with EOS-MLS, CloudSat-CPR and CALIOP-CALIPSO are presented. Then, the diurnal variation over land and over open ocean for partial ice water path is reported. Over land, a pronounced diurnal variation peaking strongly in the afternoon/early evening was found. Over the open ocean, little temporal dependence was encountered. This data set is publicly available for download in HDF5 format.

  7. CLOUD COMPUTING AND SECURITY

    Directory of Open Access Journals (Sweden)

    Asharani Shinde

    2015-10-01

    Full Text Available This document gives an insight into Cloud Computing giving an overview of key features as well as the detail study of exact working of Cloud computing. Cloud Computing lets you access all your application and documents from anywhere in the world, freeing you from the confines of the desktop thus making it easier for group members in different locations to collaborate. Certainly cloud computing can bring about strategic, transformational and even revolutionary benefits fundamental to future enterprise computing but it also offers immediate and pragmatic opportunities to improve efficiencies today while cost effectively and systematically setting the stage for the strategic change. As this technology makes the computing, sharing, networking easy and interesting, we should think about the security and privacy of information too. Thus the key points we are going to be discussed are what is cloud, what are its key features, current applications, future status and the security issues and the possible solutions.

  8. Formation of Massive Molecular Cloud Cores by Cloud-cloud Collision

    OpenAIRE

    Inoue, Tsuyoshi; Fukui, Yasuo

    2013-01-01

    Recent observations of molecular clouds around rich massive star clusters including NGC3603, Westerlund 2, and M20 revealed that the formation of massive stars could be triggered by a cloud-cloud collision. By using three-dimensional, isothermal, magnetohydrodynamics simulations with the effect of self-gravity, we demonstrate that massive, gravitationally unstable, molecular cloud cores are formed behind the strong shock waves induced by the cloud-cloud collision. We find that the massive mol...

  9. Cloud Scheduler: a resource manager for distributed compute clouds

    CERN Document Server

    Armstrong, P; Bishop, A; Charbonneau, A; Desmarais, R; Fransham, K; Hill, N; Gable, I; Gaudet, S; Goliath, S; Impey, R; Leavett-Brown, C; Ouellete, J; Paterson, M; Pritchet, C; Penfold-Brown, D; Podaima, W; Schade, D; Sobie, R J

    2010-01-01

    The availability of Infrastructure-as-a-Service (IaaS) computing clouds gives researchers access to a large set of new resources for running complex scientific applications. However, exploiting cloud resources for large numbers of jobs requires significant effort and expertise. In order to make it simple and transparent for researchers to deploy their applications, we have developed a virtual machine resource manager (Cloud Scheduler) for distributed compute clouds. Cloud Scheduler boots and manages the user-customized virtual machines in response to a user's job submission. We describe the motivation and design of the Cloud Scheduler and present results on its use on both science and commercial clouds.

  10. Cloud Computing: A study of cloud architecture and its patterns

    Directory of Open Access Journals (Sweden)

    Mandeep Handa,

    2015-05-01

    Full Text Available Cloud computing is a general term for anything that involves delivering hosted services over the Internet. Cloud computing is a paradigm shift following the shift from mainframe to client–server in the early 1980s. Cloud computing can be defined as accessing third party software and services on web and paying as per usage. It facilitates scalability and virtualized resources over Internet as a service providing cost effective and scalable solution to customers. Cloud computing has evolved as a disruptive technology and picked up speed with the presence of many vendors in cloud computing space. The evolution of cloud computing from numerous technological approaches and business models such as SaaS, cluster computing, high performance computing, etc., signifies that the cloud IDM can be considered as a superset of all the corresponding issues from these paradigms and many more. In this paper we will discuss Life cycle management, Cloud architecture, Pattern in Cloud IDM, Volatility of Cloud relations.

  11. A Cybernetics Social Cloud

    OpenAIRE

    Chang, Victor

    2016-01-01

    This paper proposes a Social Cloud, which presents the system design, development and analysis. The technology is based on the BOINC open source software, our hybrid Cloud, Facebook Graph API and our development in a new Facebook API, SocialMedia. The creation of SocialMedia API with its four functions can ensure a smooth delivery of Big Data processing in the Social Cloud, with four selected examples provided. The proposed solution is focused on processing the contacts who click like or comm...

  12. Point cloud densification

    OpenAIRE

    Forsman, Mona

    2010-01-01

    Several automatic methods exist for creating 3D point clouds extracted from 2D photos. In manycases, the result is a sparse point cloud, unevenly distributed over the scene.After determining the coordinates of the same point in two images of an object, the 3D positionof that point can be calculated using knowledge of camera data and relative orientation. A model created from a unevenly distributed point clouds may loss detail and precision in thesparse areas. The aim of this thesis is to stud...

  13. Trusted cloud computing

    CERN Document Server

    Krcmar, Helmut; Rumpe, Bernhard

    2014-01-01

    This book documents the scientific results of the projects related to the Trusted Cloud Program, covering fundamental aspects of trust, security, and quality of service for cloud-based services and applications. These results aim to allow trustworthy IT applications in the cloud by providing a reliable and secure technical and legal framework. In this domain, business models, legislative circumstances, technical possibilities, and realizable security are closely interwoven and thus are addressed jointly. The book is organized in four parts on "Security and Privacy", "Software Engineering and

  14. Provenance for the Cloud

    OpenAIRE

    Muniswamy-Reddy, Kiran-Kumar; MACKO Peter; Seltzer, Margo I.

    2010-01-01

    The cloud is poised to become the next computing environment for both data storage and computation due to its pay-as-you-go and provision-as-you-go models. Cloud storage is already being used to back up desktop user data, host shared scientific data, store web application data, and to serve web pages. Today’s cloud stores, however, are missing an important ingredient: provenance. Provenance is metadata that describes the history of an object. We make the case that provenance is crucial for da...

  15. Cloud Computing Security

    OpenAIRE

    Ngongang, Guy

    2011-01-01

    This project aimed to show how possible it is to use a network intrusion detection system in the cloud. The security in the cloud is a concern nowadays and security professionals are still finding means to make cloud computing more secure. First of all the installation of the ESX4.0, vCenter Server and vCenter lab manager in server hardware was successful in building the platform. This allowed the creation and deployment of many virtual servers. Those servers have operating systems and a...

  16. Gas phase synthesis of amino-, cyano- and nitroso-compounds in interstellar clouds

    International Nuclear Information System (INIS)

    From laboratory data relating to several hundreds of ion-atom and ion-molecule reactions at thermal energies, the authors qualitatively describe probable chemical paths to the synthesis of amino-, cyano- and nitroso-compounds in interstellar clouds. (Auth.)

  17. Io's sodium cloud - Explanation of the east-west asymmetries

    Science.gov (United States)

    Smyth, W. H.

    1979-01-01

    An explanation of the east-west asymmetries of Io's sodium clouds is suggested based upon the force experienced by sodium atoms as they resonantly scatter sunlight and upon the ability of this force to alter the cloud atom orbits, as determined by the gravitational fields of Io and Jupiter. Orbit calculations illustrating the time-dependent changes in the sodium atom trajectories produced by the solar radiation force as a function of Io's orbital location are presented in support of this explanation. This theory agrees with the idea that sodium atoms are emitted from the satellite nonisotropically and at a constant rate. These conclusions may be important in studying the global effects of active volcanoes and the intense satellite plasma torus discovered for Io from Voyager I spacecraft measurements.

  18. Cloud migration patterns: a multi-cloud service architecture perspective

    OpenAIRE

    Jamshidi, Pooyan; Pahl, Claus; Chinenyeze, Samuel; Liu, Xiaodong

    2015-01-01

    Many organizations migrate their on-premise software systems to the cloud. However, current coarse-grained cloud migration solutions have made a transparent migration of on-premise applications to the cloud a difficult, sometimes trial-and-error based endeavor. This paper suggests a catalogue of fine-grained service-based cloud architecture migration patterns that target multi-cloud settings and are specified with architectural notations. The proposed migration patterns are based on empirical...

  19. Cloud Scheduler: a resource manager for distributed compute clouds

    OpenAIRE

    Armstrong, P.; Agarwal, A.; Bishop, A.; Charbonneau, A.; Desmarais, R.; Fransham, K.; Hill, N.; Gable, I.; Gaudet, S; Goliath, S.; Impey, R.; Leavett-Brown, C.; Ouellete, J.; Paterson, M; Pritchet, C.

    2010-01-01

    The availability of Infrastructure-as-a-Service (IaaS) computing clouds gives researchers access to a large set of new resources for running complex scientific applications. However, exploiting cloud resources for large numbers of jobs requires significant effort and expertise. In order to make it simple and transparent for researchers to deploy their applications, we have developed a virtual machine resource manager (Cloud Scheduler) for distributed compute clouds. Cloud Scheduler boots and ...

  20. DATA MINING FOR DATA CLOUD AND COMPUTE CLOUD

    OpenAIRE

    PROF. UZMA ALI, PROF. PUNAM KHANDAR

    2013-01-01

    Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over a network (typically the Internet). The name comes from the use of a cloud-shaped symbol as an abstraction for the complex infrastructure it contains in system diagrams. Cloud computing entrusts remote services with a user's data, software and computation. A storage cloud provides storage services, while a compute cloud provides compute services. We describe the design of the Sector ...

  1. Absorption feedback in stratocumulus clouds Influence on cloud top albedo

    OpenAIRE

    BOERS, REINOUT; Mitchell, Ross M.

    2011-01-01

    This paper proposes a feedback mechanism which modifies the enhancement of cloud top albedo expected from an increased concentration of cloud condensation nuclei (CCN). The mechanism is based on the thermodynamic tendency of the cloud to stabilize itself against changes in the absorption of solar radiation. For optically thin clouds, this absorption feedback leads to a reduction in the anticipated albedo enhancement, while for optically thick clouds, an amplification of the albedo enhancement...

  2. Molecular clouds near supernova remnants

    International Nuclear Information System (INIS)

    The physical properties of molecular clouds near supernova remnants were investigated. Various properties of the structure and kinematics of these clouds are used to establish their physical association with well-known remmnants. An infrared survey of the most massive clouds revealed embedded objects, probably stars whose formation was induced by the supernova blast wave. In order to understand the relationship between these and other molecular clouds, a control group of clouds was also observed. Excitation models for dense regions of all the clouds are constructed to evaluate molecular abundances in these regions. Those clouds that have embedded stars have lower molecular abundances than the clouds that do not. A cloud near the W28 supernova remnant also has low abundances. Molecular abundances are used to measure an important parameter, the electron density, which is not directly observable. In some clouds extensive deuterium fractionation is observed which confirms electron density measurements in those clouds. Where large deuterium fractionation is observed, the ionization rate in the cloud interior can also be measured. The electron density and ionization rate in the cloud near W28 are higher than in most clouds. The molecular abundances and electron densities are functions of the chemical and dynamical state of evolution of the cloud. Those clouds with lowest abundances are probably the youngest clouds. As low-abundance clouds, some clouds near supernova remnants may have been recently swept from the local interstellar material. Supernova remnants provide sites for star formation in ambient clouds by compressing them, and they sweep new clouds from more diffuse local matter

  3. AtomPy: an open atomic-data curation environment

    Science.gov (United States)

    Bautista, Manuel; Mendoza, Claudio; Boswell, Josiah S; Ajoku, Chukwuemeka

    2014-06-01

    We present a cloud-computing environment for atomic data curation, networking among atomic data providers and users, teaching-and-learning, and interfacing with spectral modeling software. The system is based on Google-Drive Sheets, Pandas (Python Data Analysis Library) DataFrames, and IPython Notebooks for open community-driven curation of atomic data for scientific and technological applications. The atomic model for each ionic species is contained in a multi-sheet Google-Drive workbook, where the atomic parameters from all known public sources are progressively stored. Metadata (provenance, community discussion, etc.) accompanying every entry in the database are stored through Notebooks. Education tools on the physics of atomic processes as well as their relevance to plasma and spectral modeling are based on IPython Notebooks that integrate written material, images, videos, and active computer-tool workflows. Data processing workflows and collaborative software developments are encouraged and managed through the GitHub social network. Relevant issues this platform intends to address are: (i) data quality by allowing open access to both data producers and users in order to attain completeness, accuracy, consistency, provenance and currentness; (ii) comparisons of different datasets to facilitate accuracy assessment; (iii) downloading to local data structures (i.e. Pandas DataFrames) for further manipulation and analysis by prospective users; and (iv) data preservation by avoiding the discard of outdated sets.

  4. Cloud computing basics for librarians.

    Science.gov (United States)

    Hoy, Matthew B

    2012-01-01

    "Cloud computing" is the name for the recent trend of moving software and computing resources to an online, shared-service model. This article briefly defines cloud computing, discusses different models, explores the advantages and disadvantages, and describes some of the ways cloud computing can be used in libraries. Examples of cloud services are included at the end of the article. PMID:22289098

  5. Taxonomy of cloud computing services

    NARCIS (Netherlands)

    Hoefer, C.N.; Karagiannis, G.

    2010-01-01

    Cloud computing is a highly discussed topic, and many big players of the software industry are entering the development of cloud services. Several companies want to explore the possibilities and benefits of cloud computing, but with the amount of cloud computing services increasing quickly, the need

  6. IBM SmartCloud essentials

    CERN Document Server

    Schouten, Edwin

    2013-01-01

    A practical, user-friendly guide that provides an introduction to cloud computing using IBM SmartCloud, along with a thorough understanding of resource management in a cloud environment.This book is great for anyone who wants to get a grasp of what cloud computing is and what IBM SmartCloud has to offer. If you are an IT specialist, IT architect, system administrator, or a developer who wants to thoroughly understand the cloud computing resource model, this book is ideal for you. No prior knowledge of cloud computing is expected.

  7. Entrainment, Drizzle, and Cloud Albedo

    Science.gov (United States)

    Ackerman, A. S.; Kirkpatrick, J. P.; Stevens, D. E.; Toon, O. B.

    2004-01-01

    Increased aerosol and hence droplet concentrations in polluted clouds are expected to inhibit precipitation and thereby increase cloud water, leading to more reflective clouds that partially offset global warming. Yet polluted clouds are not generally observed to hold more water. Much of the uncertainty regarding the indirect aerosol effect stems from inadequate understanding of such changes in cloud water. Detailed simulations show that the relative humidity of air overlying stratocumulus is a leading factor determining whether cloud water increases or decreases when precipitation is suppressed. When the overlying air is dry, cloud water can decrease as droplet concentrations increase.

  8. Cloud Computing For Microfinances

    CERN Document Server

    V, Suma; M, Vaidehi; Nair, T R Gopalakrishnan

    2012-01-01

    Evolution of Science and Engineering has led to the growth of several commercial applications. The wide spread implementation of commercial based applications has in turn directed the emergence of advanced technologies such as cloud computing. India has well proven itself as a potential hub for advanced technologies including cloud based industrial market. Microfinance system has emerged out as a panacea to Indian economy since the population encompasses of people who come under poverty and below poverty index. However, one of the key challenges in successful operation of microfinance system in India has given rise to integration of financial services using sophisticated cloud computing model. This paper, therefore propose a fundamental cloud-based microfinance model in order to reduce high transaction risks involved during microfinance operations in an inexpensive and efficient manner.

  9. Entangled Cloud Storage

    DEFF Research Database (Denmark)

    Ateniese, Giuseppe; Dagdelen, Özgür; Damgård, Ivan Bjerre;

    2012-01-01

    Entangled cloud storage enables a set of clients {P_i} to “entangle” their files {f_i} into a single clew c to be stored by a (potentially malicious) cloud provider S. The entanglement makes it impossible to modify or delete significant part of the clew without affecting all files in c. A clew...... keeps the files in it private but still lets each client P_i recover his own data by interacting with S; no cooperation from other clients is needed. At the same time, the cloud provider is discouraged from altering or overwriting any significant part of c as this will imply that none of the clients can...... recover their files. We provide theoretical foundations for entangled cloud storage, introducing the notion of an entangled encoding scheme that guarantees strong security requirements capturing the properties above. We also give a concrete construction based on privacy-preserving polynomial interpolation...

  10. CloudETL

    DEFF Research Database (Denmark)

    Liu, Xiufeng; Thomsen, Christian; Pedersen, Torben Bach

    2014-01-01

    Extract-Transform-Load (ETL) programs process data into data warehouses (DWs). Rapidly growing data volumes demand systems that scale out. Recently, much attention has been given to MapReduce for parallel handling of massive data sets in cloud environments. Hive is the most widely used RDBMS...... powerful Pig platform for data processing on MapReduce does not support such dimensional ETL processing. To remedy this, we present the ETL framework CloudETL which uses Hadoop to parallelize ETL execution and to process data into Hive. The user defines the ETL process by means of high-level constructs and...... transformations and does not have to worry about technical MapReduce details. CloudETL supports different dimensional concepts such as star schemas and SCDs. We present how CloudETL works and uses different performance optimizations including a purpose-specific data placement policy to co-locate data. Further, we...

  11. Cloud benchmarking for performance

    OpenAIRE

    Varghese, Blesson; Akgun, Ozgur; Miguel, Ian; Thai, Long; Barker, Adam

    2014-01-01

    How can applications be deployed on the cloud to achieve maximum performance? This question has become significant and challenging with the availability of a wide variety of Virtual Machines (VMs) with different performance capabilities in the cloud. The above question is addressed by proposing a six step benchmarking methodology in which a user provides a set of four weights that indicate how important each of the following groups: memory, processor, computation and storage are to the applic...

  12. Toward Cloud Computing Evolution

    OpenAIRE

    Susanto, Heru; Almunawar, Mohammad Nabil; Kang, Chen Chin

    2012-01-01

    -Information Technology (IT) shaped the success of organizations, giving them a solid foundation that increases both their level of efficiency as well as productivity. The computing industry is witnessing a paradigm shift in the way computing is performed worldwide. There is a growing awareness among consumers and enterprises to access their IT resources extensively through a "utility" model known as "cloud computing." Cloud computing was initially rooted in distributed grid-based computing. ...

  13. VIRTUALIZATION IN CLOUD COMPUTING

    OpenAIRE

    LAKSHAY MALHOTRA; DEVYANI AGARWAL; ARUNIMA JAISWAL

    2014-01-01

    Cloud computing technology is one of the biggest milestones in leading us to next generation technology and booming up business and IT field. It helps to overcome the problems of data loss, accessing data whenever needed and data security. This technology is mainly service oriented and focuses on cost reduction, hardware reduction and pay just for service concept. Virtualization in cloud computing is making a virtual image of the storage devices, servers or network resources so that they can ...

  14. Cloud services with cataloging

    OpenAIRE

    Sagar M. Gurav; Rohit R. Wadkar

    2014-01-01

    In today’s fast paced world, information and communication technologies are dramatically transforming our society. Now a days, cloud computing is fast growing technology in the computer as well as information technology field. It is a recent innovation that is helping the computing industry in distributed computing. Cloud computing is a variety of different types of computing concepts that involve a large number of computers connected through a real-time communication network....

  15. Quantum Clouds: A future perspective

    OpenAIRE

    Bhambri, Satish

    2014-01-01

    Quantum computing and cloud computing are two giants for futuristic computing. Both technologies complement each other. Quantum clouds, therefore, is deploying the resources of quantum computation in a cloud environment to provide solution to the challenges and problems faced by present model of classical cloud computation. State of the art challenges faced by the cloud such as VM migration, data security, traffic management can be addressed by the quantum principles. But the merging of these...

  16. Cloud Computing Vs. Grid Computing

    OpenAIRE

    Seyyed Mohsen Hashemi; Amid Khatibi Bardsiri

    2012-01-01

    Cloud computing emerges as one of the hottest topic in field of information technology. Cloud computing is based on several other computing research areas such as HPC, virtualization, utility computing and grid computing. In order to make clear the essential of cloud computing, we propose the characteristics of this area which make cloud computing being cloud computing and distinguish it from other research areas. The service oriented, loose coupling, strong fault tolerant, business model and...

  17. Towards a community cloud storage

    OpenAIRE

    Liu, Ying; Vlassov, Vladimir; Navarro Moldes, Leandro

    2014-01-01

    Community Clouds, usually built upon community networks, operate in a more disperse environment compared to a data center Cloud, with lower capacity and less reliable servers separated by a more heterogeneous and less predictable network interconnection. These differences raise challenges when deploying Cloud applications in a community Cloud. Open Stack Swift is an open source distributed storage system, which provides stand alone highly available and scalable storage from Open Stack Cloud c...

  18. Autonomic Cloud Computing: Research Perspective

    OpenAIRE

    Gill, Sukhpal Singh

    2015-01-01

    Cloud computing is an evolving utility computing mechanism in which cloud consumer can detect, choose and utilize the resources (infrastructure, software and platform) and provide service to user based on pay per use model as computing utilities. Current computing mechanism is effective, particular for medium and small cloud based companies, in which it permits easy and reliable access to cloud services like infrastructure, software and platform. Present cloud computing is almost similar to t...

  19. Underestimation of Oceanic Warm Cloud Occurrences by the Cloud Profiling Radar Aboard CloudSat

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The Cloud Profi ling Radar (CPR) onboard CloudSat is an active sensor specifi cally dedicated to cloud detection. Compared to passive remote sensors, CPR plays a unique role in investigating the occurrence of multi-layer clouds and depicting the internal vertical structure of clouds. However, owing to contamination from ground clutter, CPR refl ectivity signals are invalid in the lowest 1 km above the surface, leading to numerous missed detections of warm clouds. In this study, by using 1-yr CPR and MODIS (Moderate Resolution Imaging Spectroradiometer) synchronous data, those CPR-missed oceanic warm clouds that are identifi ed as cloudy by MODIS are examined. It is demonstrated that CPR severely underestimates the occurrence of oceanic warm clouds, with a global-average miss rate of about 0.43. Over the tropical and subtropical oceans, the CPR-missed clouds tend to occur in regions with relatively low sea surface temperature. CPR misses almost all warm clouds with cloud tops lower than 1 km, and the miss rate reduces with increasing cloud top. As for clouds with cloud tops higher than 2 km, the negative bias of CPR-captured warm cloud occurrence falls below 3%. The cloud top height of CPR-missed warm clouds ranges from 0.6 to 1.2 km, and these clouds mostly have evidently small optical depths and droplet eff ective radii. The vertically integrated cloud liquid water content of CPR-missed warm clouds is smaller than 50 g m−2 . It is also revealed that CPR misses some warm clouds that have small optical depths or small droplet sizes, besides those limited in the boundary layer below about 1 km due to ground clutter.

  20. Rydberg atoms in ultracold plasmas

    Science.gov (United States)

    Rolston, Steven

    2009-05-01

    Ultracold plasmas are formed through the photoionization of laser-cooled atoms, or spontaneous ionization of a dense cloud of Rydberg atoms or now molecules[1]. Ultracold plasmas are inherently metastable, as the ions and electrons would be in a lower energy state bound together as atoms. The dominant process of atom formation in these plasmas is three-body recombination, a collision between two electrons and an ion that leads to the formation of a Rydberg atom. This collisional process is not only important in determining the lifetime and density of the plasma, but is also critical in determining the time evolution of the temperature. The formation of the Rydberg atoms is accompanied by an increase in electron energy for the extra electron in the collision, and is a source of heating in these plasmas. Classical three-body recombination theory scales as T-9/2, and thus as a plasma cools due to a process such as adiabatic expansion, recombination-induced heating turns on, limiting the temperature [2]. The Rydberg atoms formed live in the plasma and contribute to the temperature dynamics, as collisions with plasma electrons can change the principal quantum number of the Rydberg atom, driving it to more tightly bound states (a source of plasma heating) or to higher states (a source of plasma cooling). If the plasma is cold and dense enough to be strongly coupled, classical three-body recombination theory breaks down. Recent theoretical work [3] suggests that the rate limits as the plasma gets strongly coupled. I will review the role of Rydberg atoms in ultracold plasmas and prospects for probing Rydberg collisions in the strongly coupled environment. [4pt] [1] J. P. Morrison, et al., Phys. Rev. Lett. 101, 205005 (2008 [0pt] [2] R. S. Fletcher, X. Zhang, and S. L. Rolston, Phys. Rev. Lett. 99, 145001 (2007 [0pt] [3] T. Pohl, private communication.

  1. Design and Construction of an Atomic Clock on an Atom Chip

    International Nuclear Information System (INIS)

    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; mF = -1> and |2; 1> of the electronic ground state of the 87Rb 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)

  2. An Atom Trap Relying on Optical Pumping

    CERN Document Server

    Bouyer, P; Dahan, M B; Michaud, A; Salomon, C; Dalibard, J

    1994-01-01

    We have investigated a new radiation pressure trap which relies on optical pumping and does not require any magnetic field. It employs six circularly polarized divergent beams and works on the red of a $J_{g} \\longrightarrow J_{e} = J_{g} + 1$ atomic transition with $J_{g} \\geq 1/2$. We have demonstrated this trap with cesium atoms from a vapour cell using the 852 nm $J_{g} = 4 \\longrightarrow J_{e} = 5$ resonance transition. The trap contained up to $3 \\cdot 10^{7}$ atoms in a cloud of $1/\\sqrt{e}$ radius of 330 $\\mu$m.

  3. Imaging of microwave fields using ultracold atoms

    CERN Document Server

    Boehi, Pascal; Haensch, Theodor W; Treutlein, Philipp; 10.1063/1.3470591

    2010-01-01

    We report a technique that uses clouds of ultracold atoms as sensitive, tunable, and non-invasive probes for microwave field imaging with micrometer spatial resolution. The microwave magnetic field components drive Rabi oscillations on atomic hyperfine transitions whose frequency can be tuned with a static magnetic field. Readout is accomplished using state-selective absorption imaging. Quantitative data extraction is simple and it is possible to reconstruct the distribution of microwave magnetic field amplitudes and phases. While we demonstrate 2d imaging, an extension to 3d imaging is straightforward. We use the method to determine the microwave near-field distribution around a coplanar waveguide integrated on an atom chip.

  4. Nonequilibrium dynamics, Optimal Control and Nanofibers on an Atom Chip

    International Nuclear Information System (INIS)

    Full text: We present experiments on dynamical scaling of many-particle states, performed on degenerate 87Rb Bose gases in a time dependent trapping potential. A stochastic optimal control scheme has been implemented to manipulate the motional dynamics of such clouds, with prospects to engineer specific nonequilibrium states. Further, we present a novel atom - photon interface based on integrating optical nanofibers and nanofiber - cavities on an atom chip. Applications encompass light storage and nonlinear interactions between photons within the device, facilitated by the high optical densities and low temperatures of ultracold atom clouds in a chip trap, as well as the high transmission of an optical nanofiber. (author)

  5. Atomic secrecy

    International Nuclear Information System (INIS)

    An article, The H-Bomb Secret: How We Got It, Why We're Telling It, by Howard Morland was to be published in The Progressive magazine in February, 1979. The government, after learning of the author's and the editors' intention to publish the article and failing to persuade them to voluntarily delete about 20% of the text and all of the diagrams showing how an H-bomb works, requested a court injunction against publication. Acting under the Atomic Energy Act of 1954, US District Court Judge Robert W. Warren granted the government's request on March 26. Events dealing with the case are discussed in this publication. Section 1, Progressive Hydrogen Bomb Case, is discussed under the following: Court Order Blocking Magazine Report; Origins of the Howard Morland Article; Author's Motives, Defense of Publication; and Government Arguments Against Disclosure. Section 2, Access to Atomic Data Since 1939, contains information on need for secrecy during World War II; 1946 Atomic Energy Act and its effects; Soviet A-Bomb and the US H-Bomb; and consequences of 1954 Atomic Energy Act. Section 3, Disputed Need for Atomic Secrecy, contains papers entitled: Lack of Studies on H-Bomb Proliferation; Administration's Position on H-Bombs; and National Security Needs vs Free Press

  6. Software for Hydrogenic Atoms and Orbitals Visualization

    Directory of Open Access Journals (Sweden)

    Kowit KITTIWUTTHISAKDI

    2005-06-01

    Full Text Available A program was developed in java for hydrogenic atoms and orbitals visualization. The first 18 atoms in the periodic table were approximated with a hydrogenic wave-function. This simple hydrogenic wave-function allowed quick calculation for real-time interactive visualization. Electron cloud based models were employed and displayed by a ray-tracing technique. One or more orbitals that defined an atom could be selected and displayed. A user could zoom in, zoom out, and rotate the displayed cloud in real time. The approximation method for probability integrals was summation. The intensity of color at each point on the screen directly related to the integrated probability in finding the electron across the viewer%s eye path.

  7. Non-destructive Faraday imaging of dynamically controlled ultracold atoms

    Science.gov (United States)

    Gajdacz, Miroslav; Pedersen, Poul L.; Mørch, Troels; Hilliard, Andrew J.; Arlt, Jan; Sherson, Jacob F.

    2013-08-01

    We describe an easily implementable method for non-destructive measurements of ultracold atomic clouds based on dark field imaging of spatially resolved Faraday rotation. The signal-to-noise ratio is analyzed theoretically and, in the absence of experimental imperfections, the sensitivity limit is found to be identical to other conventional dispersive imaging techniques. The dependence on laser detuning, atomic density, and temperature is characterized in a detailed comparison with theory. Due to low destructiveness, spatially resolved images of the same cloud can be acquired up to 2000 times. The technique is applied to avoid the effect of shot-to-shot fluctuations in atom number calibration, to demonstrate single-run vector magnetic field imaging and single-run spatial imaging of the system's dynamic behavior. This demonstrates that the method is a useful tool for the characterization of static and dynamically changing properties of ultracold atomic clouds.

  8. Non-destructive Faraday imaging of dynamically controlled ultracold atoms

    Energy Technology Data Exchange (ETDEWEB)

    Gajdacz, Miroslav; Pedersen, Poul L.; Mørch, Troels; Hilliard, Andrew J.; Arlt, Jan; Sherson, Jacob F. [Danish National Research Foundation Center for Quantum Optics, Institut for Fysik og Astronomi, Aarhus Universitet, Ny Munkegade 120, 8000 Aarhus C (Denmark)

    2013-08-15

    We describe an easily implementable method for non-destructive measurements of ultracold atomic clouds based on dark field imaging of spatially resolved Faraday rotation. The signal-to-noise ratio is analyzed theoretically and, in the absence of experimental imperfections, the sensitivity limit is found to be identical to other conventional dispersive imaging techniques. The dependence on laser detuning, atomic density, and temperature is characterized in a detailed comparison with theory. Due to low destructiveness, spatially resolved images of the same cloud can be acquired up to 2000 times. The technique is applied to avoid the effect of shot-to-shot fluctuations in atom number calibration, to demonstrate single-run vector magnetic field imaging and single-run spatial imaging of the system's dynamic behavior. This demonstrates that the method is a useful tool for the characterization of static and dynamically changing properties of ultracold atomic clouds.

  9. Non-destructive Faraday imaging of dynamically controlled ultracold atoms

    International Nuclear Information System (INIS)

    We describe an easily implementable method for non-destructive measurements of ultracold atomic clouds based on dark field imaging of spatially resolved Faraday rotation. The signal-to-noise ratio is analyzed theoretically and, in the absence of experimental imperfections, the sensitivity limit is found to be identical to other conventional dispersive imaging techniques. The dependence on laser detuning, atomic density, and temperature is characterized in a detailed comparison with theory. Due to low destructiveness, spatially resolved images of the same cloud can be acquired up to 2000 times. The technique is applied to avoid the effect of shot-to-shot fluctuations in atom number calibration, to demonstrate single-run vector magnetic field imaging and single-run spatial imaging of the system's dynamic behavior. This demonstrates that the method is a useful tool for the characterization of static and dynamically changing properties of ultracold atomic clouds

  10. Atomic theories

    CERN Document Server

    Loring, FH

    2014-01-01

    Summarising the most novel facts and theories which were coming into prominence at the time, particularly those which had not yet been incorporated into standard textbooks, this important work was first published in 1921. The subjects treated cover a wide range of research that was being conducted into the atom, and include Quantum Theory, the Bohr Theory, the Sommerfield extension of Bohr's work, the Octet Theory and Isotopes, as well as Ionisation Potentials and Solar Phenomena. Because much of the material of Atomic Theories lies on the boundary between experimentally verified fact and spec

  11. Cloud networking understanding cloud-based data center networks

    CERN Document Server

    Lee, Gary

    2014-01-01

    Cloud Networking: Understanding Cloud-Based Data Center Networks explains the evolution of established networking technologies into distributed, cloud-based networks. Starting with an overview of cloud technologies, the book explains how cloud data center networks leverage distributed systems for network virtualization, storage networking, and software-defined networking. The author offers insider perspective to key components that make a cloud network possible such as switch fabric technology and data center networking standards. The final chapters look ahead to developments in architectures

  12. Interstellar Atomic Abundances

    CERN Document Server

    Jenkins, E B

    2003-01-01

    A broad array of interstellar absorption features that appear in the ultraviolet spectra of bright sources allows us to measure the abundances and ionization states of many important heavy elements that exist as free atoms in the interstellar medium. By comparing these abundances with reference values in the Sun, we find that some elements have abundances relative to hydrogen that are approximately consistent with their respective solar values, while others are depleted by factors that range from a few up to around 1000. These depletions are caused by the atoms condensing into solid form onto dust grains. Their strengths are governed by the volatility of compounds that are produced, together with the densities and velocities of the gas clouds. We may characterize the depletion trends in terms of a limited set of parameters; ones derived here are based on measurements of 15 elements toward 144 stars with known values of N(H I) and N(H2). In turn, these parameters may be applied to studies of the production, de...

  13. Open Source in Cloud Computing

    Directory of Open Access Journals (Sweden)

    Gaurav Bawa

    2012-03-01

    Full Text Available Cloud computing is emerging as the latest BUZZ word in Information Technology. There is going to be a great shift from traditional network computing to cloud computing. The features of Cloud computing - Pay as you go and Virtualization has made it a long run in advance technologies. This paper is a brief survey based of readings on “cloud computing” and the role of open source in cloud computing. The paper will also review about the flexible bandwidth of the cloud applications and its tools. The point of discussion in Information Technology sector is that the mainstream adoption of cloud computing creates hindrance for many user. This paper will contradict this theory and let us know how cloud computing is going to change the scenario of network computing and the way open source shapes the cloud computing

  14. Atoms as Qed bound atoms

    International Nuclear Information System (INIS)

    The relevance of Quantum Electrodynamics (Qed) in contemporary atomic structure theory is reviewed. Recent experimental advances allow both the production of heavy ions of high charge as well as the measurement of atomic properties with a precision never achieved before. The description of heavy atoms with few electrons via the successive incorporation of one, two, etcetera photons in a rigorous manner and within the bound state Furry representation of Qed is technically feasible. For many-electron atoms the many-body (correlation) effects are very important and it is practically impossible to evaluate all the relevant Feynman diagrams to the required accuracy. Thus, it is necessary to develop a theoretical scheme in which the radiative and nonradiative effects are taken into account in an effective way making emphasis in electronic correlation. Preserving gauge invariance, and avoiding both continuum dissolution and variational collapse are basic problems that must be solved when using effective potential methods and finite-basis representations of them. In this context, we shall discuss advances and problems in the description of atoms as Qed bound states. (Author)

  15. The Evolution of Gas Clouds Falling in the Magnetized Galactic Halo: High-Velocity Clouds (HVCs) Originated in the Galactic Fountain

    Science.gov (United States)

    Kwak, Kyujin; Shelton, Robin L.; Raley, Elizabeth A.

    2009-07-01

    In the Galactic fountain scenario, supernovae and/or stellar winds propel material into the Galactic halo. As the material cools, it condenses into clouds. By using FLASH three-dimensional magnetohydrodynamic simulations, we model and study the dynamical evolution of these gas clouds after they form and begin to fall toward the Galactic plane. In our simulations, we assume that the gas clouds form at a height of z = 5 kpc above the Galactic midplane, then begin to fall from rest. We investigate how the cloud's evolution, dynamics, and interaction with the interstellar medium (ISM) are affected by the initial mass of the cloud. We find that clouds with sufficiently large initial densities (n >= 0.1 H atoms cm-3) accelerate sufficiently and maintain sufficiently large column densities as to be observed and identified as high-velocity clouds (HVCs) even if the ISM is weakly magnetized (1.3 μG). However, the ISM can provide noticeable resistance to the motion of a low-density cloud (n effects of various possible magnetic field configurations. As expected, the ISM's resistance is greatest when the magnetic field is strong and perpendicular to the motion of the cloud. The trajectory of the cloud is guided by the magnetic field lines in cases where the magnetic field is oriented diagonal to the Galactic plane. The model cloud simulations show that the interactions between the cloud and the ISM can be understood via analogy to the shock tube problem which involves shock and rarefaction waves. We also discuss accelerated ambient gas, streamers of material ablated from the clouds, and the cloud's evolution from a sphere-shaped to a disk- or cigar-shaped object.

  16. An explanation of the east-west asymmetry of Io's sodium cloud

    International Nuclear Information System (INIS)

    Since the discovery of a cloud of neutral sodium atoms accompanying the jovian satellite, Io, in its orbit, asymmetries of part of the cloud (region B)2 have often been noted. Brightness variations with orbital longitude and asymmetries found by comparing images taken at orbital longitudes differing by 1800 have been explained as effects of solar radiation pressure. The author shows that, given reasonable assumptions, the east-west brightness asymmetry can be explained by temporal changes in the number of emitting atoms in the cloud caused by atmospheric shielding of the surface. (author)

  17. Adolescent Interstellar Cloud Poised to Make Star-forming Debut

    Science.gov (United States)

    2001-06-01

    Astronomers using the National Science Foundation's (NSF) 140-foot radio telescope at the National Radio Astronomy Observatory (NRAO) in Green Bank, W.Va., have discovered a highly unusual, massive interstellar cloud that appears poised to begin a burst of star formation. The cloud may be the first ever to be detected in the transition between atomic and molecular states. NRAO scientists Felix J. Lockman and Anthony H. Minter presented their findings at the American Astronomical Society meeting in Pasadena, Calif. Radio Image of G28.17+0.05 The scientists discovered the cloud, identified as G28.17+0.05, lying along the inner plane of the Milky Way Galaxy, approximately 16,300 light-years from Earth. Observations of the cloud indicate that it is near one of the Galaxy's sweeping spiral arms, which are outlined by young stars and the massive clouds that form them. Lockman and Minter speculate that as the interstellar cloud slams into the Galactic arm, the resulting shock wave may be precipitating the conversion of the neutral hydrogen atoms into heavier molecules, which could herald the onset of star formation. "These may be the first observations of a cloud that is in the transition between the neutral atomic hydrogen and molecular phases," said Lockman. "This provides astronomers a unique opportunity to study the chemistry of very young interstellar clouds, which could give us significant insights into the early stages of star formation and the structure of the Galaxy." Interstellar clouds that contain neutral atomic hydrogen, called HI (H-one) clouds, are thought of as giant, cold blobs of gas. Researchers study these objects because they offer intriguing glimpses of the composition of our Galaxy and the cosmos, and reveal much about how stars and planets are born. Hydrogen atoms in these clouds give off natural signals (at the 21-cm wavelength), which can be detected only by radio telescopes. The scientists discovered that this HI cloud was unusual in many

  18. Counting the clouds

    International Nuclear Information System (INIS)

    Cloud processes are very important for the global circulation of the atmosphere. It is now possible, though very expensive, to simulate the global circulation of the atmosphere using a model with resolution fine enough to explicitly represent the larger individual clouds. An impressive preliminary calculation of this type has already been performed by Japanese scientists, using the Earth Simulator. Within the next few years, such global cloud-resolving models (GCRMs) will be applied to weather prediction, and later they will be used in climatechange simulations. The tremendous advantage of GCRMs, relative to conventional lowerresolution global models, is that GCRMs can avoid many of the questionable 'parameterizations' used to represent cloud effects in lower-resolution global models. Although cloud microphysics, turbulence, and radiation must still be parameterized in GCRMs, the high resolution of a GCRM simplifies these problems considerably, relative to conventional models. The United States currently has no project to develop a GCRM, although we have both the computer power and the expertise to do it. A research program aimed at development and applications of GCRMs is outlined

  19. Trust management in cloud services

    CERN Document Server

    Noor, Talal H; Bouguettaya, Athman

    2014-01-01

    This book describes the design and implementation of Cloud Armor, a novel approach for credibility-based trust management and automatic discovery of cloud services in distributed and highly dynamic environments. This book also helps cloud users to understand the difficulties of establishing trust in cloud computing and the best criteria for selecting a service cloud. The techniques have been validated by a prototype system implementation and experimental studies using a collection of real world trust feedbacks on cloud services.The authors present the design and implementation of a novel pro

  20. Scale analysis of convective clouds

    Directory of Open Access Journals (Sweden)

    Micha Gryschka

    2008-12-01

    Full Text Available The size distribution of cumulus clouds due to shallow and deep convection is analyzed using satellite pictures, LES model results and data from the German rain radar network. The size distributions found can be described by simple power laws as has also been proposed for other cloud data in the literature. As the observed precipitation at ground stations is finally determined by cloud numbers in an area and individual sizes and rain rates of single clouds, the cloud size distributions might be used for developing empirical precipitation forecasts or for validating results from cloud resolving models being introduced to routine weather forecasts.

  1. The Evolution of Gas Clouds Falling in the Magnetized Galactic Halo: High Velocity Clouds (HVCs) Originated in the Galactic Fountain

    CERN Document Server

    Kwak, Kyujin; Raley, Elizabeth A

    2009-01-01

    In the Galactic fountain scenario, supernovae and/or stellar winds propel material into the Galactic halo. As the material cools, it condenses into clouds. By using FLASH three-dimensional magnetohydrodynamic simulations, we model and study the dynamical evolution of these gas clouds after they form and begin to fall toward the Galactic plane. In our simulations, we assume that the gas clouds form at a height of z=5 kpc above the Galactic midplane, then begin to fall from rest. We investigate how the cloud's evolution, dynamics, and interaction with the interstellar medium (ISM) are affected by the initial mass of the cloud. We find that clouds with sufficiently large initial densities (> 0.1 hydrogen atoms per cc) accelerate sufficiently and maintain sufficiently large column densities as to be observed and identified as high-velocity clouds (HVCs) even if the ISM is weakly magnetized (1.3 micro Gauss). We also investigate the effects of various possible magnetic field configurations. As expected, the ISM's ...

  2. Performance Evaluation of Private Clouds Eucalyptus versus CloudStack

    Directory of Open Access Journals (Sweden)

    Mumtaz M.Ali AL-Mukhtar

    2014-06-01

    Full Text Available the number of open source cloud management platforms is increasing day-by-day. The features of these software vary significantly and this creates a difficulty for the cloud consumers to choose the software based on their business and scientific requirements. This paper evaluates Eucalyptus and CloudStack, the two most popular open source platforms used to build private Infrastructure as a service (IaaS clouds. The performance of virtual machines (VMs initiated and managed by Eucalyptus and CloudStack are evaluated in terms of CPU utilization, memory bandwidth, disk I/O access speed, and network performance using suitable benchmarks. Different VM management operations such as add, delete and live migration are also assessed to determine which cloud solution is more suitable than other to be adopted as a private cloud solution. As a further performance testing, a simple web application has been implemented on the both clouds to evaluate their suitability in web application hosting.

  3. Transition to the Cloud

    DEFF Research Database (Denmark)

    Hedman, Jonas; Xiao, Xiao

    2016-01-01

    The rising of cloud computing has dramatically changed the way software companies provide and distribute their IT product and related services over the last decades. Today, most software is bought offthe-shelf and distributed over the Internet. This transition is greatly influencing how software...... companies operate. In this paper, we present a case study of an ERP vendor for SMB (small and mediumsize business) in making a transition towards a cloud-based business model. Through the theoretical lens of ecosystem, we are able to analyze the evolution of the vendor and its business network as a whole......, and find that the relationship between vendor and Value-added-Reseller (VAR) is greatly affected. We conclude by presenting critical issues and challenges for managing such cloud transition....

  4. Cloud Service Brokerage-2014: Towards the Multi-cloud Ecosystem

    OpenAIRE

    Simons, A.J.H.; Rossini, A; Paraskakis, I.; Jensen, J

    2015-01-01

    In the future multi-cloud ecosystem, many cloud providers and consumers will interact to create, discover, negotiate and use software services. Cloud service brokers will play a central role in bringing providers and consumers together, assisting with software service creation (from abstract models to platform-specific deployments), multi-cloud translation (model-driven adaptation and deployment of services) quality assurance (governance; functional testing and monitoring), service continuity...

  5. Towards Data Interoperability of Cloud Infrastructures Using Cloud Storage Services

    OpenAIRE

    Pflanzner, Tamás; Kertész, Attila

    2014-01-01

    Cloud Computing is becoming more and more popular, and various cloud services have appeared to make our lives easier. Mobile devices can also bene t from Cloud services: the huge data users produce with these devices are continuously posted to online services, which may require the modi cation of these data. Using cloud storage services together with computation-intensive infrastructure services can provide a suitable solution for these needs. In this paper we address the open issue of data i...

  6. Cloud ERP and Cloud Accounting Software in Romania

    OpenAIRE

    Gianina MIHAI

    2015-01-01

    Nowadays, Cloud Computing becomes a more and more fashionable concept in the IT environment. There is no unanimous opinion on the definition of this concept, as it covers several versions of the newly emerged stage in the IT. But in fact, Cloud Computing should not suggest anything else than simplicity. Thus, in short, simple terms, Cloud Computing can be defined as a solution to use external IT resources (servers, storage media, applications and services), via Internet. Cloud computing is no...

  7. Storm and cloud dynamics

    CERN Document Server

    Cotton, William R

    1992-01-01

    This book focuses on the dynamics of clouds and of precipitating mesoscale meteorological systems. Clouds and precipitating mesoscale systems represent some of the most important and scientifically exciting weather systems in the world. These are the systems that produce torrential rains, severe winds including downburst and tornadoes, hail, thunder and lightning, and major snow storms. Forecasting such storms represents a major challenge since they are too small to be adequately resolved by conventional observing networks and numerical prediction models.Key Features* Key Highlight

  8. Cloud chemistry on Jupiter

    OpenAIRE

    Carlson, B. E.; Prather, M. J.; W. B. Rossow

    1987-01-01

    Aqueous chemistry on Uranus affects the atmospheric abundances of NH3 and H2S below the methane cloud base. Here a complete thermochemical equilibrium model for the H2O-NH3-H2S system is presented. Inclusion of H2S increases the aqueous removal of NH3 to 20-30 percent, but aqueous chemistry alone cannot account for the depletion of NH3 in the 150-200-K region of the atmosphere required to fit microwave observations. Formation of NH4SH clouds can account for the observed depletion provided the...

  9. Opaque cloud detection

    Science.gov (United States)

    Roskovensky, John K.

    2009-01-20

    A method of detecting clouds in a digital image comprising, for an area of the digital image, determining a reflectance value in at least three discrete electromagnetic spectrum bands, computing a first ratio of one reflectance value minus another reflectance value and the same two values added together, computing a second ratio of one reflectance value and another reflectance value, choosing one of the reflectance values, and concluding that an opaque cloud exists in the area if the results of each of the two computing steps and the choosing step fall within three corresponding predetermined ranges.

  10. Multi-Cloud Application Design through Cloud Service Composition

    OpenAIRE

    Kyriakos Kritikos; Dimitris Plexousakis

    2015-01-01

    A paper that proposes a cloud service composition approach able to optimally compose different types of cloud services by simultaneously satisfying various types of user requirements. Its novel approach in handling these types, which are not concurrently supported by any cloud design tool, include quality, deployment, security, placement and cost requirements.

  11. Gold volatile species atomization and preconcentration in quartz devices for atomic absorption spectrometry

    International Nuclear Information System (INIS)

    The on-line atomization of gold volatile species was studied and the results were compared with thermodynamic calculations in several quartz atomizers, namely: diffusion flame, flame-in-gas-shield, flame-in-plain-tube, externally heated T-tube and externally heated flame-in-T-tube. Atomization mechanism in the explored devices is proposed, where volatile species are converted to thermodynamically stable AuH at elevated temperature over 500 °C and then atomized by an interaction with a cloud of hydrogen radicals. Because of its inherent simplicity and robustness, diffusion flame was employed as a reference atomizer. It yielded atomization efficiency of 70 to 100% and a very good long time reproducibility of peak area sensitivity: 1.6 to 1.8 s μg−1. Six and eleven times higher sensitivity, respectively, was provided by atomizers with longer light paths in the observation volume, i.e. externally heated T-tube and externally heated flame-in-T-tube. The latter one, offering limit of detection below 0.01 μg ml−1, appeared as the most prospective for on-line atomization. Insight into the mechanism of atomization of gold volatile species, into the fate of free atoms and into subsequent analyte transfer allowed to assess possibilities of in-atomizer preconcentration of gold volatile species: it is unfeasible with quartz atomizers but a sapphire tube atomizer could be useful in this respect. - Highlights: • On-line atomization of gold volatile species for AAS in quartz devices was studied. • Atomization mechanism was proposed and atomization efficiency was estimated. • Possibilities of in-atomizer preconcentration of gold volatile species were assessed

  12. Cloud Based Applications and Platforms (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Brodt-Giles, D.

    2014-05-15

    Presentation to the Cloud Computing East 2014 Conference, where we are highlighting our cloud computing strategy, describing the platforms on the cloud (including Smartgrid.gov), and defining our process for implementing cloud based applications.

  13. Clouding behaviour in surfactant systems.

    Science.gov (United States)

    Mukherjee, Partha; Padhan, Susanta K; Dash, Sukalyan; Patel, Sabita; Mishra, Bijay K

    2011-02-17

    A study on the phenomenon of clouding and the applications of cloud point technology has been thoroughly discussed. The phase behaviour of clouding and various methods adopted for the determination of cloud point of various surfactant systems have been elucidated. The systems containing anionic, cationic, nonionic surfactants as well as microemulsions have been reviewed with respect to their clouding phenomena and the effects of structural variation in the surfactant systems have been incorporated. Additives of various natures control the clouding of surfactants. Electrolytes, nonelectrolytes, organic substances as well as ionic surfactants, when present in the surfactant solutions, play a major role in the clouding phenomena. The review includes the morphological study of clouds and their applications in the extraction of trace inorganic, organic materials as well as pesticides and protein substrates from different sources. PMID:21296314

  14. Internet ware cloud computing :Challenges

    CERN Document Server

    Qamar, S; Singh, Mrityunjay

    2010-01-01

    After decades of engineering development and infrastructural investment, Internet connections have become commodity product in many countries, and Internet scale "cloud computing" has started to compete with traditional software business through its technological advantages and economy of scale. Cloud computing is a promising enabling technology of Internet ware Cloud Computing is termed as the next big thing in the modern corporate world. Apart from the present day software and technologies, cloud computing will have a growing impact on enterprise IT and business activities in many large organizations. This paper provides an insight to cloud computing, its impacts and discusses various issues that business organizations face while implementing cloud computing. Further, it recommends various strategies that organizations need to adopt while migrating to cloud computing. The purpose of this paper is to develop an understanding of cloud computing in the modern world and its impact on organizations and businesse...

  15. Cosmic rays, clouds, and climate

    DEFF Research Database (Denmark)

    Marsh, N.; Svensmark, Henrik

    2000-01-01

    A correlation between a global average of low cloud cover and the flux of cosmic rays incident in the atmosphere has been observed during the last solar cycle. The ionising potential of Earth bound cosmic rays are modulated by the state of the heliosphere, while clouds play an important role in the...... between cosmic ray flux and low cloud top temperature. The temperature of a cloud depends on the radiation properties determined by its droplet distribution. Low clouds are warm (> 273 K) and therefore consist of liquid water droplets. At typical atmospheric supersaturations (similar to1%) a liquid cloud...... drop will only form in the presence of an aerosol, which acts as a condensation site. The droplet distribution of a cloud will then depend on the number of aerosols activated as cloud condensation nuclei (CCN) and the level of super saturation. Based on observational evidence it is argued that a...

  16. Security Dynamics of Cloud Computing

    OpenAIRE

    Khaled M. Khan

    2009-01-01

    This paper explores various dimensions of cloud computing security. It argues that security concerns of cloud computing need to be addressed from the perspective of individual stakeholder. Security focuses of cloud computing are essentially different in terms of its characteristics and business model. Conventional way of viewing as well as addressing security such as ‘bolting-in’ on the top of cloud computing may not work well. The paper attempts to portray the security spectrum necessary for...

  17. Cloud services, networking, and management

    CERN Document Server

    da Fonseca, Nelson L S

    2015-01-01

    Cloud Services, Networking and Management provides a comprehensive overview of the cloud infrastructure and services, as well as their underlying management mechanisms, including data center virtualization and networking, cloud security and reliability, big data analytics, scientific and commercial applications. Special features of the book include: State-of-the-art content. Self-contained chapters for readers with specific interests. Includes commercial applications on Cloud (video services and games).

  18. Drafting a Cloud Computing Contract

    OpenAIRE

    2011-01-01

    As a new service method in delivering computing resources, cloud computing technology poses a challenge towards the application of existing laws that have a bearing on such technology. Considering this fact, this thesis firstly attempts to identify the legal problems associated with cloud computing technology. Secondly, this thesis will review the current practice on how providers generally govern their relationship with the customers in the cloud T&C, and concomitantly, how the cloud provide...

  19. Development of a Windows Azure cloud application

    OpenAIRE

    Andolšek, Matej

    2013-01-01

    This thesis describes the development of a typical ".NET" applications, migration to the Windows Azure cloud platform and the design of cloud computing, which allows the user to access all services through the Internet. With cloud computing there are three types of service models: platform as a service, software as a service and infrastructure as a service. There are three types of cloud systems, namely the public cloud, private cloud and hybrid cloud. Each type of cloud has its own advantage...

  20. Research on cloud computing solutions

    Directory of Open Access Journals (Sweden)

    Liudvikas Kaklauskas

    2015-07-01

    Full Text Available Cloud computing can be defined as a new style of computing in which dynamically scala-ble and often virtualized resources are provided as a services over the Internet. Advantages of the cloud computing technology include cost savings, high availability, and easy scalability. Voas and Zhang adapted six phases of computing paradigms, from dummy termi-nals/mainframes, to PCs, networking computing, to grid and cloud computing. There are four types of cloud computing: public cloud, private cloud, hybrid cloud and community. The most common and well-known deployment model is Public Cloud. A Private Cloud is suited for sensitive data, where the customer is dependent on a certain degree of security.According to the different types of services offered, cloud computing can be considered to consist of three layers (services models: IaaS (infrastructure as a service, PaaS (platform as a service, SaaS (software as a service. Main cloud computing solutions: web applications, data hosting, virtualization, database clusters and terminal services. The advantage of cloud com-puting is the ability to virtualize and share resources among different applications with the objective for better server utilization and without a clustering solution, a service may fail at the moment the server crashes.DOI: 10.15181/csat.v2i2.914

  1. A View from the Clouds

    Science.gov (United States)

    Chudnov, Daniel

    2010-01-01

    Cloud computing is definitely a thing now, but it's not new and it's not even novel. Back when people were first learning about the Internet in the 1990s, every diagram that one saw showing how the Internet worked had a big cloud in the middle. That cloud represented the diverse links, routers, gateways, and protocols that passed traffic around in…

  2. The Basics of Cloud Computing

    Science.gov (United States)

    Kaestner, Rich

    2012-01-01

    Most school business officials have heard the term "cloud computing" bandied about and may have some idea of what the term means. In fact, they likely already leverage a cloud-computing solution somewhere within their district. But what does cloud computing really mean? This brief article puts a bit of definition behind the term and helps one…

  3. Understanding and monitoring cloud services

    NARCIS (Netherlands)

    Drago, Idilio

    2013-01-01

    Cloud services have changed the way computing power is delivered to customers. The advantages of the cloud model have fast resulted in powerful providers. However, this success has not come without problems. Cloud providers have been related to major failures, including outages and performance degra

  4. iCloud standard guide

    CERN Document Server

    Alfi, Fauzan

    2013-01-01

    An easy-to-use guide, filled with tutorials that will teach you how to set up and use iCloud, and profit from all of its marvellous features.This book is for anyone with basic knowledge of computers and mobile operations. Prior knowledge of cloud computing or iCloud is not expected.

  5. VMware private cloud computing with vCloud director

    CERN Document Server

    Gallagher, Simon

    2013-01-01

    It's All About Delivering Service with vCloud Director Empowered by virtualization, companies are not just moving into the cloud, they're moving into private clouds for greater security, flexibility, and cost savings. However, this move involves more than just infrastructure. It also represents a different business model and a new way to provide services. In this detailed book, VMware vExpert Simon Gallagher makes sense of private cloud computing for IT administrators. From basic cloud theory and strategies for adoption to practical implementation, he covers all the issues. You'll lea

  6. High-Velocity Clouds

    NARCIS (Netherlands)

    Wakker, Bart P.; Woerden, Hugo van; Oswalt, Terry D.; Gilmore, Gerard

    2013-01-01

    The high-velocity clouds (HVCs) are gaseous objects that do not partake in differential galactic rotation, but instead have anomalous velocities. They trace energetic processes on the interface between the interstellar material in the Galactic disk and intergalactic space. Three different processes

  7. Towards autonomous vehicular clouds

    Directory of Open Access Journals (Sweden)

    Stephan Olariu

    2011-09-01

    Full Text Available The dawn of the 21st century has seen a growing interest in vehicular networking and its myriad potential applications. The initial view of practitioners and researchers was that radio-equipped vehicles could keep the drivers informed about potential safety risks and increase their awareness of road conditions. The view then expanded to include access to the Internet and associated services. This position paper proposes and promotes a novel and more comprehensive vision namely, that advances in vehicular networks, embedded devices and cloud computing will enable the formation of autonomous clouds of vehicular computing, communication, sensing, power and physical resources. Hence, we coin the term, autonomous vehicular clouds (AVCs. A key feature distinguishing AVCs from conventional cloud computing is that mobile AVC resources can be pooled dynamically to serve authorized users and to enable autonomy in real-time service sharing and management on terrestrial, aerial, or aquatic pathways or theaters of operations. In addition to general-purpose AVCs, we also envision the emergence of specialized AVCs such as mobile analytics laboratories. Furthermore, we envision that the integration of AVCs with ubiquitous smart infrastructures including intelligent transportation systems, smart cities and smart electric power grids will have an enormous societal impact enabling ubiquitous utility cyber-physical services at the right place, right time and with right-sized resources.

  8. Predictable cloud computing

    NARCIS (Netherlands)

    Mullender, Sape J.

    2012-01-01

    The standard tools for cloud computing—processor and network virtualization—make it difficult to achieve dependability, both in terms of real time operations and fault tolerance. Virtualization multiplexes virtual resources onto physical ones, typically by time division or statistical multiplexing.

  9. CLOUD COMPUTING SECURITY ISSUES

    Directory of Open Access Journals (Sweden)

    Florin OGIGAU-NEAMTIU

    2012-01-01

    Full Text Available The term “cloud computing” has been in the spotlights of IT specialists the last years because of its potential to transform this industry. The promised benefits have determined companies to invest great sums of money in researching and developing this domain and great steps have been made towards implementing this technology. Managers have traditionally viewed IT as difficult and expensive and the promise of cloud computing leads many to think that IT will now be easy and cheap. The reality is that cloud computing has simplified some technical aspects of building computer systems, but the myriad challenges facing IT environment still remain. Organizations which consider adopting cloud based services must also understand the many major problems of information policy, including issues of privacy, security, reliability, access, and regulation. The goal of this article is to identify the main security issues and to draw the attention of both decision makers and users to the potential risks of moving data into “the cloud”.

  10. Password authentication in cloud

    Directory of Open Access Journals (Sweden)

    Indal Singh

    2015-09-01

    Full Text Available Cloud computing is an Internet-based computing, whereby shared resources, software, and information are provided to computers and other devices on demand. However, adopting a cloud computing paradigm may have positive as well as negative effects on the data security of service consumers [1]. Cloud Computing is a term used to describe both a platform and type of application. As a platform it supplies, configures and reconfigures servers, while the servers can be physical machines or virtual machines. On the other hand, Cloud Computing describes applications that are extended to be accessible through the internet and for this purpose large data centers and powerful servers are used to host the web applications and web services. Authentication is one the most important security primitive [6]. Password authentication is most widely used authentication mechanism. Password provides security mechanism for authentication and protection services against unwanted access to resource. In this paper, we applied a technique to preserve our password using graphical authentication.

  11. Computing in the Clouds

    Science.gov (United States)

    Johnson, Doug

    2010-01-01

    Web-based applications offer teachers, students, and school districts a convenient way to accomplish a wide range of tasks, from accounting to word processing, for free. Cloud computing has the potential to offer staff and students better services at a lower cost than the technology deployment models they're using now. Saving money and improving…

  12. Jupiter Clouds in Depth

    Science.gov (United States)

    2000-01-01

    [figure removed for brevity, see original site] 619 nm [figure removed for brevity, see original site] 727 nm [figure removed for brevity, see original site] 890 nmImages from NASA's Cassini spacecraft using three different filters reveal cloud structures and movements at different depths in the atmosphere around Jupiter's south pole.Cassini's cameras come equipped with filters that sample three wavelengths where methane gas absorbs light. These are in the red at 619 nanometer (nm) wavelength and in the near-infrared at 727 nm and 890 nm. Absorption in the 619 nm filter is weak. It is stronger in the 727 nm band and very strong in the 890 nm band where 90 percent of the light is absorbed by methane gas. Light in the weakest band can penetrate the deepest into Jupiter's atmosphere. It is sensitive to the amount of cloud and haze down to the pressure of the water cloud, which lies at a depth where pressure is about 6 times the atmospheric pressure at sea level on the Earth). Light in the strongest methane band is absorbed at high altitude and is sensitive only to the ammonia cloud level and higher (pressures less than about one-half of Earth's atmospheric pressure) and the middle methane band is sensitive to the ammonia and ammonium hydrosulfide cloud layers as deep as two times Earth's atmospheric pressure.The images shown here demonstrate the power of these filters in studies of cloud stratigraphy. The images cover latitudes from about 15 degrees north at the top down to the southern polar region at the bottom. The left and middle images are ratios, the image in the methane filter divided by the image at a nearby wavelength outside the methane band. Using ratios emphasizes where contrast is due to methane absorption and not to other factors, such as the absorptive properties of the cloud particles, which influence contrast at all wavelengths.The most prominent feature seen in all three filters is the polar stratospheric haze that makes Jupiter bright near the pole

  13. Seeding the Cloud

    Science.gov (United States)

    Schaffhauser, Dian

    2013-01-01

    For any institution looking to shift enterprise resource planning (ERP) systems to the cloud, big savings can be achieved--but only if the school has properly prepped "before" negotiations begin. These three steps can help: (1) Mop up the mess first; (2) Understand the true costs for services; and (3) Calculate the cost of transition.

  14. Benchmarking personal cloud storage

    NARCIS (Netherlands)

    Drago, Idilio; Bocchi, Enrico; Mellia, Marco; Slatman, Herman; Pras, Aiko

    2013-01-01

    Personal cloud storage services are data-intensive applications already producing a significant share of Internet traffic. Several solutions offered by different companies attract more and more people. However, little is known about each service capabilities, architecture and - most of all - perform

  15. AIRS-CloudSat cloud mask, radar reflectivities, and cloud classification matchups V3.2

    Data.gov (United States)

    National Aeronautics and Space Administration — This is AIRS-CloudSat collocated subset, in NetCDF 4 format. These data contain collocated: AIRS Level 1b radiances spectra, CloudSat radar reflectivities, and...

  16. Energy Scaling of Cold Atom-Atom-Ion Three-Body Recombination

    Science.gov (United States)

    Krükow, Artjom; Mohammadi, Amir; Härter, Arne; Denschlag, Johannes Hecker; Pérez-Ríos, Jesús; Greene, Chris H.

    2016-05-01

    We study three-body recombination of Ba++Rb +Rb in the mK regime where a single 138Ba+ ion in a Paul trap is immersed into a cloud of ultracold 87Rb atoms. We measure the energy dependence of the three-body rate coefficient k3 and compare the results to the theoretical prediction, k3∝Ecol-3 /4, where Ecol is the collision energy. We find agreement if we assume that the nonthermal ion energy distribution is determined by at least two different micromotion induced energy scales. Furthermore, using classical trajectory calculations we predict how the median binding energy of the formed molecules scales with the collision energy. Our studies give new insights into the kinetics of an ion immersed in an ultracold atom cloud and yield important prospects for atom-ion experiments targeting the s -wave regime.

  17. Energy scaling of cold atom-atom-ion three-body recombination

    CERN Document Server

    Krükow, Artjom; Härter, Arne; Denschlag, Johannes Hecker; Pérez-Ríos, Jesús; Greene, Chris H

    2015-01-01

    We study three-body recombination of Ba$^+$ + Rb + Rb in the mK regime where a single $^{138}$Ba$^{+}$ ion in a Paul trap is immersed into a cloud of ultracold $^{87}$Rb atoms. We measure the energy dependence of the three-body rate coefficient $k_3$ and compare the results to the theoretical prediction, $k_3 \\propto E_{\\textrm{col}}^{-3/4}$ where $E_{\\textrm{col}}$ is the collision energy. We find agreement if we assume that the non-thermal ion energy distribution is determined by at least two different micro-motion induced energy scales. Furthermore, using classical trajectory calculations we predict how the median binding energy of the formed molecules scales with the collision energy. Our studies give new insights into the kinetics of an ion immersed into an ultracold atom cloud and yield important prospects for atom-ion experiments targeting the s-wave regime.

  18. OH{sup +} IN DIFFUSE MOLECULAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Porras, A. J.; Federman, S. R. [Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606 (United States); Welty, D. E. [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Ritchey, A. M., E-mail: steven.federman@utoledo.edu, E-mail: aporras@live.unc.edu, E-mail: dwelty@oddjob.uchicago.edu, E-mail: aritchey@astro.washington.edu [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States)

    2014-01-20

    Near ultraviolet observations of OH{sup +} and OH in diffuse molecular clouds reveal a preference for different environments. The dominant absorption feature in OH{sup +} arises from a main component seen in CH{sup +} (that with the highest CH{sup +}/CH column density ratio), while OH follows CN absorption. This distinction provides new constraints on OH chemistry in these clouds. Since CH{sup +} detections favor low-density gas with small fractions of molecular hydrogen, this must be true for OH{sup +} as well, confirming OH{sup +} and H{sub 2}O{sup +} observations with the Herschel Space Telescope. Our observed correspondence indicates that the cosmic ray ionization rate derived from these measurements pertains to mainly atomic gas. The association of OH absorption with gas rich in CN is attributed to the need for a high enough density and molecular fraction before detectable amounts are seen. Thus, while OH{sup +} leads to OH production, chemical arguments suggest that their abundances are controlled by different sets of conditions and that they coexist with different sets of observed species. Of particular note is that non-thermal chemistry appears to play a limited role in the synthesis of OH in diffuse molecular clouds.

  19. Exotic atoms

    International Nuclear Information System (INIS)

    The experiments use a solid hydrogen layer to form muonic hydrogen isotopes that escape into vacuum. The method relies on transfer of the muon from protium to either a deuteron or a triton. The resulting muonic deuterium or muonic tritium will not immediately thermalize because of the very low elastic cross sections, and may be emitted from the surface of the layer. Measurements which detect decay electrons, muonic x-rays, and fusion products have been used to study the processes. A target has been constructed which exploits muonic atom emission in order to learn more about the energy dependence of transfer and muon molecular formation

  20. Atomic Clocks

    Science.gov (United States)

    Wynands, Robert

    Time is a strange thing. On the one hand it is arguably the most inaccessible physical phenomenon of all: both in that it is impossible to manipulate or modify—for all we know—and in that even after thousands of years mankind's philosophers still have not found a fully satisfying way to understand it. On the other hand, no other quantity can be measured with greater precision. Today's atomic clocks allow us to reproduce the length of the second as the SI unit of time with an uncertainty of a few parts in 1016—orders of magnitude better than any other quantity. In a sense, one can say [1

  1. Cloud Computing Security Issue: Survey

    Science.gov (United States)

    Kamal, Shailza; Kaur, Rajpreet

    2011-12-01

    Cloud computing is the growing field in IT industry since 2007 proposed by IBM. Another company like Google, Amazon, and Microsoft provides further products to cloud computing. The cloud computing is the internet based computing that shared recourses, information on demand. It provides the services like SaaS, IaaS and PaaS. The services and recourses are shared by virtualization that run multiple operation applications on cloud computing. This discussion gives the survey on the challenges on security issues during cloud computing and describes some standards and protocols that presents how security can be managed.

  2. Security for cloud storage systems

    CERN Document Server

    Yang, Kan

    2014-01-01

    Cloud storage is an important service of cloud computing, which offers service for data owners to host their data in the cloud. This new paradigm of data hosting and data access services introduces two major security concerns. The first is the protection of data integrity. Data owners may not fully trust the cloud server and worry that data stored in the cloud could be corrupted or even removed. The second is data access control. Data owners may worry that some dishonest servers provide data access to users that are not permitted for profit gain and thus they can no longer rely on the servers

  3. Stratocumulus cloud deepening through entrainment

    Science.gov (United States)

    Randall, D. A.

    1984-01-01

    Under a substantial range of realistic conditions, stratocumulus cloud top entrainment is noted to either deepen an existing cloud layer or produce clouds in an unsaturated mixed layer, though the entrained air is warmer and drier than the mixed-layer air. These results, which apply irrespective of entrainment rate-determining mechanism, imply that the cloud top entrainment instability discussed by Randall (1980) and Deardorff (1980) does not necessarily destroy a layer cloud. Examples are given which include soundings, marine layer data, and simulation results produced by the UCLA general circulation model.

  4. Single atom measurement and atomic manipulation using atomic force microscope

    International Nuclear Information System (INIS)

    This paper explains studies to measure atomic force as the force linking an atom and atom, using an atomic force microscope (AFM). First, it describes the principle and device configuration of AFM, and as an example of the atomic force measurement of Si atoms on the surface of Si(111)-(7x7), it describes the technique to measure atomic force using AFM, as well as the uncertainty of probe tip against atomic force. In addition, it describes the following items on the measurement results of chemical bonding force: (1) chemical bonding force vs physical force and chemical bonding force vs current on the surface of Si(111)-(7x7), (2) chemical bonding force and element dependence on the surface of Si/Sn(111)-(√3x√3), (3) atomic manipulation based on AMF, and (4) relationship between atomic manipulation and the size of chemical bonding force with a probe. (A.O.)

  5. LOAD MANAGEMENT IN CLOUD ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    Esha Sarkar

    2014-09-01

    Full Text Available Cloud computing is an on demand service in which shared resources, information, software and other devices are provided to the end user as per their requirement at a specific time. A cloud consists of several elements such as clients, datacenters and distributed servers. There are n number of clients and end users involved in cloud environment. These clients may make requests to the cloud system simultaneously, making it difficult for the cloud to manage the entire load at a time. The load can be CPU load, memory load, delay or network load. This might cause inconvenience to the clients as there may be delay in the response time or it might affect the performance and efficiency of the cloud environment. So, the concept of load balancing is very important in cloud computing to improve the efficiency of the cloud. Good load balancing makes cloud computing more efficient and improves user satisfaction. This paper gives an approach to balance the incoming load in cloud environment by making partitions of the public cloud

  6. Formation of giant molecular clouds in global spiral structures: The role of orbital dynamics and cloud-cloud collisions

    Science.gov (United States)

    Roberts, W. W., Jr.; Stewart, G. R.

    1987-01-01

    The different roles played by orbital dynamics and dissipative cloud-cloud collisions in the formation of giant molecular clouds (GMCs) in a global spiral structure are investigated. The interstellar medium (ISM) is simulated by a system of particles, representing clouds, which orbit in a spiral-perturbed, galactic gravitational field. The overall magnitude and width of the global cloud density distribution in spiral arms is very similar in the collisional and collisionless simulations. The results suggest that the assumed number density and size distribution of clouds and the details of individual cloud-cloud collisions have relatively little effect on these features. Dissipative cloud-cloud collisions play an important steadying role for the cloud system's global spiral structure. Dissipative cloud-cloud collisions also damp the relative velocity dispersion of clouds in massive associations and thereby aid in the effective assembling of GMC-like complexes.

  7. Lean computing for the cloud

    CERN Document Server

    Bauer, Eric

    2016-01-01

    Applies lean manufacturing principles across the cloud service delivery chain to enable application and infrastructure service providers to sustainably achieve the shortest lead time, best quality, and value This book focuses on lean in the context of cloud computing capacity management of applications and the physical and virtual cloud resources that support them. Lean Computing for the Cloud considers business, architectural and operational aspects of efficiently delivering valuable services to end users via cloud-based applications hosted on shared cloud infrastructure. The work also focuses on overall optimization of the service delivery chain to enable both application service and infrastructure service providers to adopt leaner, demand driven operations to serve end users more efficiently. The book’s early chapters analyze how capacity management morphs with cloud computing into interlocked physical infrastructure capacity management, virtual resou ce capacity management, and application capacity ma...

  8. Cloud Computing Utility and Applications

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar Tiwari

    2011-12-01

    Full Text Available Cloud Architecture provides services on demand basis via internet (WWW services. Application design in cloud computing environment or the applications which support cloud paradigm are on demand on the basis of user requirement. Those applications provide the support on various hardware, software and other resource requirement on demand. API used in the cloud computing provide the greater advantage to provide industrial strength, where the complex reliability and scalability logic of the underlying services remains implemented and hidden in the cloud environment. Cloud Computing provide the highest utilization in terms of utilization, resource sharing, requirement gathering and utility to the other needful resources. In this paper we discuss several utility and their applications. We provide a broad discussion which is useful for cloud computing research.

  9. Magnetic confinement of cosmic clouds

    Science.gov (United States)

    Azar, Michel; Thompson, W. B.

    1988-01-01

    The role of the magnetic field in the confinement or compression of interstellar gas clouds is reconsidered. The virial theorem for an isolated magnetized cloud in the presence of distant magnetic sources is reformulated in terms of moments of the internal and external currents, and an equilibrium condition is derived. This condition is applied to the interaction between isolated clouds for the simple- and artificial-case in which the field of each cloud is a dipole. With the simplest of statistical assumptions, the probability of any given cloud being compressed is calculated as about 10 percent, the magnetic field acting as a medium which transmits the kinetic pressure between clouds. Even when compression occurs the magnetic pressure 1/2 B-squared may decrease on leaving the cloud surface.

  10. Taming light with cold atoms

    International Nuclear Information System (INIS)

    Much of the extraordinary progress of developments in communication (e-mail, and/or internet) has been achieved due to improvements in optical communication. This paper describes a new approach which could improve the speed of communication. The ability to stop light in its tracks by passing it through a cloud of ultracold atoms could lead to new techniques for optical storage. The described slow-light experiments have triggered new physics both on the experimental and theoretical fronts. The cold atom system allows the steepest possible refractive index profiles, and therefore the most dramatic effects, as Doppler effects are eliminated. Furthermore, cold atoms provide maximum flexibility in the choice of beam geometry. This is important for the storage and retrieval of multiple pulses of optical information in an atomic medium, as it would allow individual pulses to be selectively addressed. Slow and stopped light have many potential applications in optical communication and processing, including optical information storage, ultra-sensitive optical switches, and optical delay lines. It could also be used in quantum-information processing, in which quantum-mechanical information is used for computing and communication purposes. On a very different front, slow light provides us with a totally new way of probing the unusual properties of Bose-Einstein condensates

  11. A Framework to Improve Communication and Reliability Between Cloud Consumer and Provider in the Cloud

    OpenAIRE

    Vivek Sridhar

    2014-01-01

    Cloud services consumers demand reliable methods for choosing appropriate cloud service provider for their requirements. Number of cloud consumer is increasing day by day and so cloud providers, hence requirement for a common platform for interacting between cloud provider and cloud consumer is also on the raise. This paper introduces Cloud Providers Market Platform Dashboard. This will act as not only just cloud provider discoverability but also provide timely report to consumer on cloud ser...

  12. Future of Cloud Computing in India

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar Tiwari

    2012-03-01

    Full Text Available This paper shows the future of cloud computing in India. This paper also help to understand of future of cloud computing in Indian market .This paper also show the benefits of cloud computing .Cloud computing is not very buzz in India. This paper give the new idea to understand cloud computing and cloud computing future in India. This paper also show the importance of cloud computing. Ito show the growth rate of cloud computing. This paper not only show the cloud computing market it also show the uses and benefits of cloud computing.

  13. Future of Cloud Computing in India

    Directory of Open Access Journals (Sweden)

    Pradeep Kumar Tiwari

    2012-03-01

    Full Text Available This paper shows the future of cloud computing in India. This paper also help to understand of future of cloud computing in Indian market .This paper also show the benefits of cloud computing .Cloud computing is not very buzz in India. This paper give the new idea to understand cloud computing and cloud computing future in India. This paper also show the importance of cloud computing. Ito show the growth rate of cloud computing .This paper not only show the cloud computing market it also show the uses and benefits of cloud computing

  14. Atom Skimmers and Atom Lasers Utilizing Them

    Science.gov (United States)

    Hulet, Randall; Tollett, Jeff; Franke, Kurt; Moss, Steve; Sackett, Charles; Gerton, Jordan; Ghaffari, Bita; McAlexander, W.; Strecker, K.; Homan, D.

    2005-01-01

    Atom skimmers are devices that act as low-pass velocity filters for atoms in thermal atomic beams. An atom skimmer operating in conjunction with a suitable thermal atomic-beam source (e.g., an oven in which cesium is heated) can serve as a source of slow atoms for a magneto-optical trap or other apparatus in an atomic-physics experiment. Phenomena that are studied in such apparatuses include Bose-Einstein condensation of atomic gases, spectra of trapped atoms, and collisions of slowly moving atoms. An atom skimmer includes a curved, low-thermal-conduction tube that leads from the outlet of a thermal atomic-beam source to the inlet of a magneto-optical trap or other device in which the selected low-velocity atoms are to be used. Permanent rare-earth magnets are placed around the tube in a yoke of high-magnetic-permeability material to establish a quadrupole or octupole magnetic field leading from the source to the trap. The atoms are attracted to the locus of minimum magnetic-field intensity in the middle of the tube, and the gradient of the magnetic field provides centripetal force that guides the atoms around the curve along the axis of the tube. The threshold velocity for guiding is dictated by the gradient of the magnetic field and the radius of curvature of the tube. Atoms moving at lesser velocities are successfully guided; faster atoms strike the tube wall and are lost from the beam.

  15. Atomic collisions under extreme conditions in space

    International Nuclear Information System (INIS)

    In space, atoms and molecules are often placed under the extreme conditions which are very difficult to be realized on Earth. For instance, extremely hot and dense plasmas are found in and around various stellar objects (e.g., neutron stars) on one hand and extremely cold and diffuse gases prevail in interstellar space on the other. There is so strong a magnetic field that electron clouds in atoms and molecules are distorted. The study of atomic collisions under the extreme conditions is not only helpful in understanding the astrophysical environment but also reveals new aspects of the physics of atoms and molecules. This paper is an invitation to the study. (References are not exhaustive but only provide a clue with which more details can be found.) (author)

  16. A cold 87Rb atomic beam

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Jia; Feng Yan-Ying; Xue Hong-Bo; Zhou Zhao-Ying; Zhang Wen-Dong

    2011-01-01

    We demonstrate an experimental setup for the production of a beam source of cold 87Rb atoms.The atoms are extracted from a trapped cold atomic cloud in an unbalanced three-dimensional magneto-optical trap.Via a radiation pressure difference generated by a specially designed leak tunnel along one trapping laser beam,the atoms are pushed out continuously with low velocities and a high flux.The most-probable velocity in the beam is varied from 9 m/s to 19 m/s by varying the detuning of the trapping laser beams in the magneto-optical trap and the flux can be tuned up to 4× 109 s-1 by increasing the intensity of the trapping beams.We also present a simple model for describing the dependence of the beam performance on the magneto-optical trap trapping laser intensity and the detuning.

  17. The Clouds of Isidore

    Science.gov (United States)

    2002-01-01

    These views of Hurricane Isidore were acquired by the Multi-angle Imaging SpectroRadiometer (MISR) on September 20, 2002. After bringing large-scale flooding to western Cuba, Isidore was upgraded (on September 21) from a tropical storm to a category 3hurricane. Sweeping westward to Mexico's Yucatan Peninsula, the hurricane caused major destruction and left hundreds of thousands of people homeless. Although weakened after passing over the Yucatan landmass, Isidore regained strength as it moved northward over the Gulf of Mexico.At left is a colorful visualization of cloud extent that superimposes MISR's radiometric camera-by-camera cloud mask (RCCM) over natural-color radiance imagery, both derived from data acquired with the instrument's vertical-viewing (nadir) camera. Using brightness and statistical metrics, the RCCM is one of several techniques MISR uses to determine whether an area is clear or cloudy. In this rendition, the RCCM has been color-coded, and purple = cloudy with high confidence, blue = cloudy with low confidence, green = clear with low confidence, and red = clear with high confidence.In addition to providing information on meteorological events, MISR's data products are designed to help improve our understanding of the influences of clouds on climate. Cloud heights and albedos are among the variables that govern these influences. (Albedo is the amount of sunlight reflected back to space divided by the amount of incident sunlight.) The center panel is the cloud-top height field retrieved using automated stereoscopic processing of data from multiple MISR cameras. Areas where heights could not be retrieved are shown in dark gray. In some areas, such as the southern portion of the image, the stereo retrieval was able to detect thin, high clouds that were not picked up by the RCCM's nadir view. Retrieved local albedo values for Isidore are shown at right. Generation of the albedo product is dependent upon observed cloud radiances as a function of

  18. Storing Quantum Information via Atomic Dark Resonances

    OpenAIRE

    Caruso, Filippo

    2010-01-01

    In this thesis, after a brief review of some concepts of Quantum Optics, we analyze a three-level atomic system in the conditions of electromagnetically induced transparency (EIT), and we investigate the propagation of a gaussian pulse along a cigar-shaped cloud of both cold and hot atoms in EIT regime. In particular, we show that it is possible to amplify a slow propagating pulse without population inversion. We also analyze the regime of anomalous light propagation showing that it is possib...

  19. Cold atom dynamics in linear and nonlinear optical potentials

    Science.gov (United States)

    Williams, William

    This dissertation has two major components. The first is theoretical work on using multiple optical fields to control atoms. Theoretical models for creating complex optical potentials for use in atomic lithography are explored and a proposal for serial writing of an atomic beam is presented. A proposal to compress a cloud of cold atoms to create a tightly confined cigar shaped cloud of dense atoms for use in atom optics experiments and quantum control is also presented. The second component focuses on the study of nonlinear self-focusing in cold Cesium atoms. Modulation instability is explored in a cold atom environment which produces novel effects such as red detuned modulational instability. Several experimental setups are explored and compared with theoretical models. The first is two-wave mixing which consists of a strong pump beam and a weak probe beam crossing in a MOT. The second is using a counter-propagating pump beam to balance the radiation force of the forward propagating pump beam. The third is retro-reflecting both the probe and the pump beam which creates a more complicated experimental setup with multiple atomic gratings. Energy transfer from the pump to the probe beam via atomic density redistribution for red detuning is presented.

  20. Atomic hydrogen in the Orion star-forming region

    International Nuclear Information System (INIS)

    A large-scale survey of atomic hydrogen in Orion reveals low-density material with a total mass comparable to that in dense molecular clouds. The atomic gas is sufficiently dense that it can shield the molecular material from photodissociative radiation and provide a pressure link to the low-density intercloud medium. An excess of H I emission comes from photodissociation fronts near the bright stars and from a giant shell in the Orion Belt region. This shell may have caused the apparent bifurcation between the Orion A and B clouds, and the associated pressures may have induced peculiar motions and star formation in NGC 2023 and 2024. 49 refs

  1. Giant Helium Dimers Produced by Photoassociation of Ultracold Metastable Atoms

    OpenAIRE

    Leonard, J.; Walhout, M.; Mosk, A. P.; Mueller, T.; Leduc, M; Cohen-Tannoudji, C.

    2003-01-01

    We produce giant helium dimers by photoassociation of metastable helium atoms in a magnetically trapped, ultracold cloud. The photoassociation laser is detuned red of the atomic $2^3S_1 - 2^3P_0 $ line and produces strong heating of the sample when resonant with molecular bound states. The temperature of the cloud serves as an indicator of the molecular spectrum. We report good agreement between our spectroscopic measurements and our calculations of the five bound states belonging to a $0_u^+...

  2. Accelerating the averaging rate of atomic ensemble clock stability using atomic phase lock

    International Nuclear Information System (INIS)

    We experimentally demonstrated that the stability of an atomic clock improves at its fastest rate τ −1 (where τ is the averaging time) when the phase of a local oscillator is genuinely compared to the continuous phase of many atoms in a single trap (an atomic phase lock). For this demonstration, we developed a simple method that repeatedly monitors the atomic phase while retaining its coherence by observing only a portion of the whole ion cloud. Using this new method, we measured the continuous phase over three measurement cycles, and thereby improved the stability scaling from τ−1/2 to τ −1 during the three measurement cycles. This simple method provides a path by which atomic clocks can approach a quantum projection noise limit, even when the measurement noise is dominated by the technical noise. (paper)

  3. Positron clouds within thunderstorms

    CERN Document Server

    Dwyer, Joseph R; Hazelton, Bryna J; Grefenstette, Brian W; Kelley, Nicole A; Lowell, Alexander W; Schaal, Meagan M; Rassoul, Hamid K

    2015-01-01

    We report the observation of two isolated clouds of positrons inside an active thunderstorm. These observations were made by the Airborne Detector for Energetic Lightning Emissions (ADELE), an array of six gamma-ray detectors, which flew on a Gulfstream V jet aircraft through the top of an active thunderstorm in August 2009. ADELE recorded two 511 keV gamma-ray count rate enhancements, 35 seconds apart, each lasting approximately 0.2 seconds. The enhancements, which were about a factor of 12 above background, were both accompanied by electrical activity as measured by a flat-plate antenna on the underside of the aircraft. The energy spectra were consistent with a source mostly composed of positron annihilation gamma rays, with a prominent 511 keV line clearly visible in the data. Model fits to the data suggest that the aircraft was briefly immersed in clouds of positrons, more than a kilometer across. It is not clear how the positron clouds were created within the thunderstorm, but it is possible they were ca...

  4. Climate sensitivity to cloud optical properties

    OpenAIRE

    Hu, Y.; Stamnes, K.

    2011-01-01

    A radiative–convective model was developed to investigate the sensitivity of climate to cloud optical properties and the related feedback processes. This model demonstrates that the Earth's surface temperature increases with cloud optical depth when the clouds are very thin but decreases with cloud optical depth when the cloud shortwave (solar) radiative forcing is larger than the cloud longwave (terrestrial) radiative forcing. When clouds are included in the model, the magnitude of the green...

  5. Cloud processing, cloud evaporation and Angström exponent

    Directory of Open Access Journals (Sweden)

    G.-J. Roelofs

    2008-07-01

    Full Text Available With a cloud parcel model we investigated how cloud processing and cloud evaporation modify the size distribution and the Angström exponent of an aerosol population. Cloud processing causes a decrease in particle concentrations, relatively most efficiently in the coarse mode, and reduces the relative dispersion of the aerosol distribution. As a result the Angström exponent of the aerosol increases. The Angström exponent is subject to other influences. It is very sensitive for relative humidity, especially between 95% and 100%. In addition, kinetic limitations delay droplet evaporation during cloud dissipation, which hampers a direct relation between the Angström exponent and the relative humidity. Consequently, a direct interpretation of the Angström exponent in terms of aerosol properties that play a role in aerosol-cloud interactions, such as the fine mode fraction, is rather complex.

  6. Icebergs in the Clouds: the Other Risks of Cloud Computing

    CERN Document Server

    Ford, Bryan

    2012-01-01

    Cloud computing is appealing from management and efficiency perspectives, but brings risks both known and unknown. Well-known and hotly-debated information security risks, due to software vulnerabilities, insider attacks, and side-channels for example, may be only the "tip of the iceberg." As diverse, independently developed cloud services share ever more fluidly and aggressively multiplexed hardware resource pools, unpredictable interactions between load-balancing and other reactive mechanisms could lead to dynamic instabilities or "meltdowns." Non-transparent layering structures, where alternative cloud services may appear independent but share deep, hidden resource dependencies, may create unexpected and potentially catastrophic failure correlations, reminiscent of financial industry crashes. Finally, cloud computing exacerbates already-difficult digital preservation challenges, because only the provider of a cloud-based application or service has the ability to archive a "live," functional copy of a cloud...

  7. ATLAS cloud R and D

    International Nuclear Information System (INIS)

    The computing model of the ATLAS experiment was designed around the concept of grid computing and, since the start of data taking, this model has proven very successful. However, new cloud computing technologies bring attractive features to improve the operations and elasticity of scientific distributed computing. ATLAS sees grid and cloud computing as complementary technologies that will coexist at different levels of resource abstraction, and two years ago created an R and D working group to investigate the different integration scenarios. The ATLAS Cloud Computing R and D has been able to demonstrate the feasibility of offloading work from grid to cloud sites and, as of today, is able to integrate transparently various cloud resources into the PanDA workload management system. The ATLAS Cloud Computing R and D is operating various PanDA queues on private and public resources and has provided several hundred thousand CPU days to the experiment. As a result, the ATLAS Cloud Computing R and D group has gained a significant insight into the cloud computing landscape and has identified points that still need to be addressed in order to fully utilize this technology. This contribution will explain the cloud integration models that are being evaluated and will discuss ATLAS' learning during the collaboration with leading commercial and academic cloud providers.

  8. Interaction between atoms and slow light: a design study

    CERN Document Server

    Zang, Xiaorun; Faggiani, Rémi; Gill, Christopher; Petrov, Plamen G; Hugonin, Jean-Paul; Bernon, Simon; Bouyer, Philippe; Boyer, Vincent; Lalanne, Philippe

    2015-01-01

    The emerging field of on-chip integration of nanophotonic devices and cold atoms offers extremely-strong and pure light-matter interaction schemes, which may have profound impact on quantum information science. In this context, a longstanding obstacle is to achieve strong interaction between single atoms and single photons, while at the same time trap atoms in vacuum at large separation distances from dielectric surfaces. In this letter, we study new waveguide geometries that challenge these conflicting objectives. The designed photonic crystal waveguide is expected to offer a good compromise, which additionally allow for easy manipulation of atomic clouds around the structure.

  9. Cloud on Linux Operating System

    Directory of Open Access Journals (Sweden)

    Pritee Gavhane

    2013-04-01

    Full Text Available The term “cloud” is analyzed to “Internet”. The term “Cloud computing” is based on cloud drawings used in the past to represent telephone networks and later to depict internet. Cloud computing is a internet based computing where virtual shared servers provide software, infrastructure, platform, devices and other resources and hosting to customers on a pay-as-you basis. All information that a digitized system has to offer is a provided as a service in the cloud computing model. Users can access these services available on the “Internet cloud” without having any previous know - how on managingthe resources involved. Cloud computing is a computing model not a technology. In this model customers plug into the “cloud” to access IT resources which are price and provided “on demand”.Cloud computing is a style of computing where massively scalable IT related capabilities are provided “as a service” to external customers using internet technologies. Virtualization is the ability to run multiple OS (software’s on a single physical systems and share the underlying a hardware resources. Cloud computing provide services which are mainly of an OS running on a single virtualized computing environment with middleware layers that attempt to combine physical and virtualized resources from multiple OS and specialized application engines. This paper, we discuss about the virtual distributed OS. Cloud OS, which provide the maximum features cloud computing by using c panel. The cloud OS works on the principles layout by LINUX. The cloud OS aims to provide a simple programming abstraction to available cloud resources, strong isolation techniquesbetween cloud processes and strong integration with network resources.

  10. Box traps on an atom chip for one-dimensional quantum gases

    CERN Document Server

    van Es, J J P; van Amerongen, A H; Rétif, C; Whitlock, S; van Druten, N J

    2009-01-01

    We present the implementation of tailored trapping potentials for ultracold gases on an atom chip. We realize highly elongated traps with box-like confinement along the long, axial direction combined with conventional harmonic confinement along the two radial directions. The design, fabrication and characterization of the atom chip and the box traps is described. We load ultracold ($\\lesssim1 \\mu$K) clouds of $^{87}$Rb in a box trap, and demonstrate Bose-gas focusing as a means to characterize these atomic clouds in arbitrarily shaped potentials. Our results show that box-like axial potentials on atom chips are very promising for studies of one-dimensional quantum gases.

  11. Long-range gravitational-like interaction in a neutral atomic cold gas

    CERN Document Server

    Chalony, Maryvonne; Marcos, B; Olivetti, A; Wilkowski, David

    2012-01-01

    A quasi resonant laser induces a long-range attractive force within a cloud of cold atoms. We take advantage of this force to build in the lab quasi 1D systems of particles with a gravitational-like interaction, at a fluid level of modeling. We give experimental evidences of such an interaction in a Strontium cold gas, studying the density profile of the cloud, its size as a function of the number of atoms and its breathing oscillations.

  12. Impacts of Cloud Computing (STOA Cloud Computing Del.3)

    OpenAIRE

    Weber, Arnd; Hallinan, Dara; Hunt, Graham; Hennen, Leonhard; Jaglo , Maggie; Nentwich, Michael; Nielsen, Rasmus Øjvind; Strauß, Stefan; Lynn, Theo; Leimbach, Timo

    2013-01-01

    Deliverable No.3 of the STOA Project "Potential and Impacts of Cloud Computing Services and Social Network Sites”This report focuses on the impacts of Cloud Computing and the resulting challenges. It is based on an evaluation of the available scientific and industry literature, as well as on expert interviews. It should be mentioned that statements regarding Cloud Computing in reports and media on this are often contradictory. One reason for this is that various definitions are used. Some aut...

  13. CLOUD PARAMETERIZATIONS, CLOUD PHYSICS, AND THEIR CONNECTIONS: AN OVERVIEW

    International Nuclear Information System (INIS)

    This paper consists of three parts. The first part is concerned with the parameterization of cloud microphysics in climate models. We demonstrate the crucial importance of spectral dispersion of the cloud droplet size distribution in determining radiative properties of clouds (e.g., effective radius), and underline the necessity of specifying spectral dispersion in the parameterization of cloud microphysics. It is argued that the inclusion of spectral dispersion makes the issue of cloud parameterization essentially equivalent to that of the droplet size distribution function, bringing cloud parameterization to the forefront of cloud physics. The second part is concerned with theoretical investigations into the spectral shape of droplet size distributions in cloud physics. After briefly reviewing the mainstream theories (including entrainment and mixing theories, and stochastic theories), we discuss their deficiencies and the need for a paradigm shift from reductionist approaches to systems approaches. A systems theory that has recently been formulated by utilizing ideas from statistical physics and information theory is discussed, along with the major results derived from it. It is shown that the systems formalism not only easily explains many puzzles that have been frustrating the mainstream theories, but also reveals such new phenomena as scale-dependence of cloud droplet size distributions. The third part is concerned with the potential applications of the systems theory to the specification of spectral dispersion in terms of predictable variables and scale-dependence under different fluctuating environments

  14. Security prospects through cloud computing by adopting multiple clouds

    DEFF Research Database (Denmark)

    Jensen, Meiko; Schwenk, Jörg; Bohli, Jens Matthias;

    2011-01-01

    Clouds impose new security challenges, which are amongst the biggest obstacles when considering the usage of cloud services. This triggered a lot of research activities in this direction, resulting in a quantity of proposals targeting the various security threats. Besides the security issues coming...... with the cloud paradigm, it can also provide a new set of unique features which open the path towards novel security approaches, techniques and architectures. This paper initiates this discussion by contributing a concept which achieves security merits by making use of multiple distinct clouds at the...

  15. Future of Cloud Computing in India

    OpenAIRE

    Mr. Pradeep Kumar Tiwari

    2012-01-01

    This paper shows the future of cloud computing in India. This paper also help to understand of future of cloud computing in Indian market .This paper also show the benefits of cloud computing .Cloud computing is not very buzz in India. This paper give the new idea to understand cloud computing and cloud computing future in India. This paper also show the importance of cloud computing. Ito show the growth rate of cloud computing. This paper not only show the cloud computing market it also show...

  16. Io's sodium cloud - Explanation of the east-west asymmetries. II

    Science.gov (United States)

    Smyth, W. H.

    1983-01-01

    A three- dimensional model for Io's sodium cloud incorporating the full effects of solar radiation acceleration associated with solar resonance scattering of atoms in the D-1 and D-2 lines is developed and applied to interpret two different but related east-west asymmetries exhibited in the cloud, using data obtained from ground-based telescopes. The physical changes produced in the cloud by the solar radiation acceleration as a function of satellite phase angle are documented, and how these changes explain the asymmetries is clarified. The model results suggest an east-west phase lag asymmetry of 10-15 degrees; results for the observed east-west intensity asymmetry of Bergstrahl (1977) are also presented. The east-west shape and intensity asymmetries are found to follow directly from the lack of circular symmetry about Jupiter of the forces acting on the cloud atoms.

  17. Trusted Cloud for Data Sharing

    Directory of Open Access Journals (Sweden)

    Vishal V.Bhanawase*1

    2014-04-01

    Full Text Available Cloud computing is a general term for anything that involves delivering hosted services over the internet. These services are broadly divided into three categories: Infrastructure-as-a-Service (IaaS, Platform-as-a Service (PaaS and Software-as-a-Service (SaaS. A cloud service has three distinct characteristics that differentiate it from traditional hosting. It is sold on demand, typically by the minute or the hour; it is elastic - a user can have as much or as little of a service as they want at any given time and the service is fully managed by the cloud service provider (the consumer needs nothing but a personal computer and Internet access.The advantage of cloud is cost savings. The prime disadvantage is security. Cloud computing is used by many software industries nowadays. Since the data placed in the cloud is accessible to everyone, security is not guaranteed. Cloud Computing provides the way to share distributed resources and services that belong to different organizations or sites. Since Cloud Computing share distributed resources via network in the open environment thus it makes security problems. All types of users who require the secure transmission or storage of data in any kind of media or network. By this new technology, users also start worrying about losing control of their own data. The data processed on clouds are often outsourced, leading to a number of issues related to accountability, including the handling of personally identifiable information. Such fears are becoming a significant barrier to the wide adoption of cloud services. To allay users’ concerns, it is essential to provide an effective mechanism for users to monitor the usage of their data in the cloud. For example, users need to be able to ensure that their data are handled according to the service level agreements made at the time they sign on for services in the cloud.

  18. Cloud Dispersal in Turbulent Flows

    OpenAIRE

    Heitsch, F.; Slyz, A. D.; Devriendt, J. E. G.; A. Burkert

    2006-01-01

    Cold clouds embedded in warm media are very common objects in astrophysics. Their disruption timescale depends strongly on the dynamical configuration. We discuss the evolution of an initially homogeneous cold cloud embedded in warm turbulent gas. Within a couple of dynamical timescales, the filling factor of the cold gas within the original cloud radius drops below 50%. Turbulent diffusivities estimated from the time evolution of radial filling factor profiles are not constant with time. Col...

  19. Trust Assessment Using Cloud Broker

    OpenAIRE

    P S Pawar; Rajarajan, M.; Dimitrakos, T.; Zisman, A.

    2014-01-01

    Despite the advantages and rapid growth of Cloud computing, the cloud environments are still not sufficiently trustworthy from a customer’s perspective. Several challenges such as specification of service level agreements, standards, security measures, selection of service providers and computation of trust still persists, that concerns the customer. To deal with these challenges and provide a trustworthy environment, a mediation layer may be essential. In this paper we propose a cloud broker...

  20. Internet ware cloud computing :Challenges

    OpenAIRE

    Dr. S Qamar; Niranjan Lal,; Mrityunjay Singh

    2010-01-01

    After decades of engineering development and infrastructural investment, Internet connections have become commodity product in many countries, and Internet scale “cloud computing” has started to compete with traditional software business through its technological advantages and economy of scale. Cloud computing is a promising enabling technology of Internet ware Cloud Computing is termed as the next big thing in the modern corporate world. Apart from the present day software and technologies,...

  1. StratusLab Cloud Distribution

    OpenAIRE

    Loomis, Charles; Airaj, Mohammed; Bégin, Marc-Elian; Floros, Evangelos; Kenny, Stuart; O'Callaghan, David

    2012-01-01

    Cloud technologies provide many benefits for scientific and engineering applications, such as customised execution environments, near-instantaneous provisioning, elasticity, and the ability to run user-level services. However, a rapid, wholesale shift to using public, commercial cloud services is unlikely because of capital investments in existing resources and data management issues. To take full advantage of cloud technologies in the short term, institutes and companies must be able to depl...

  2. Cloud-Based Mobile Applications

    OpenAIRE

    Irakoze, Imelda

    2013-01-01

    The goal of this project was to use cloud computing in order to improve the computing ability of mobile devices. Processing power, storage capacity, battery lifetime, and display size present a concern for developers when creating applications for mobile devices. In addition to this, with all the different types of smartphone operating systems on the market today, a need arises for a way to create cross-platform applications and cloud computing offers a solution to that. Cloud computin...

  3. ORAT FOR GREEN CLOUD COMPUTING

    OpenAIRE

    K.L.Giridas; A.Shajin Nargunam

    2012-01-01

    As the IT trade progress towards game-changing expertise, a cloud Eco-system is gradually increasing in the country with expertise corporation ramping up employing and guiding for cloud computing. An accomplishment of green IT is probable to assist an organization in several ways like operating cost, stakeholder value, sustainability, employee morale and so on. In this paper, we propose an optimal resource allocation method for cloud computing environments. This paper progress a resource allo...

  4. LINUX BASED CLOUD OPERATING SYSTEM

    OpenAIRE

    Ravindra Gupta; Mr. Gajendra Singh; Lokesh Patel

    2012-01-01

    Cloud computing is a type of computing in which dynamically scalable and virtualized resources are provided as a service. Users need not have knowledge of, expertise in, or control over the technology infrastructure in the cloud that supports them. Furthermore, cloud computing employs a model for enabling available, convenient and on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, services) that can be rapidly provisi...

  5. Usage Control in Cloud Systems

    OpenAIRE

    Lazouski, Aliaksandr; Mancini, Gaetano; Martinelli, Fabio; Mori, Paolo

    2012-01-01

    Cloud systems [1] are becoming very common in the last years because of their advantages, such as the big computational power available on demand, and the possibility to ask for further resources or to release unused resources while the computation is running. As a matter of fact, the Cloud environment allows the user to exploit the resources he needs for his computation only when he actually needs them. Distinct Cloud service models are available, depending on the kind of resources that are ...

  6. Atomic squeezed states on an atom-chip

    International Nuclear Information System (INIS)

    In this thesis, we describe the construction of an experiment, allowing to produce 87Rb Bose-Einstein condensates on an atom chip, and then split them in a double well potential. An accurate imaging system has been developed, in order to be able to measure the absolute value of the populations of the double well within a very low noise level, almost limited by the optical shot noise. We measure atom number statistics after splitting, and directly observe number squeezed states, down to -4.9 dB at low temperatures, compared to a classical gas, of independent particles. The dependence in temperature of fluctuations has been also studied. For a thermal gas, Poissonian fluctuations are given by the probability distribution of the macroscopic configurations with a given atom number difference. In the degenerate regime, the entropy effect which favors small number differences vanishes, leading to super-Poissonian fluctuations, to more than +3.8 dB close to transition temperature. At low temperatures, the interaction energy cost associated with number fluctuations exceeds the available thermal energy, leading to sub-Poissonian fluctuations. Those two behaviours have been theoretically explained, both with a simple analytical model and a numerical one. We also measured the evolution of the relative phase between the two clouds, and its collapse due to interactions, allowing us to claim that this splitter is a coherent one. (author)

  7. Estimating cloud field coverage using morphological analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bar-Or, Rotem Z; Koren, Ilan; Altaratz, Orit, E-mail: ilan.koren@weizmann.ac.i [Department of Environmental Sciences and Energy Research, Weizmann Institute of Science, Rehovot 76100 (Israel)

    2010-01-15

    The apparent cloud-free atmosphere in the vicinity of clouds ('the twilight zone') is often affected by undetectable weak signature clouds and humidified aerosols. It is suggested here to classify the atmosphere into two classes: cloud fields, and cloud-free (away from a cloud field), while detectable clouds are included in the cloud field class as a subset. Since the definition of cloud fields is ambiguous, a robust cloud field masking algorithm is presented here, based on the cloud spatial distribution. The cloud field boundaries are calculated then on the basis of the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask products and the total cloud field area is estimated for the Atlantic Ocean (50 deg. S-50 deg. N). The findings show that while the monthly averaged cloud fraction over the Atlantic Ocean during July is 53%, the cloud field fraction may reach 97%, suggesting that cloud field properties should be considered in climate studies. A comparison between aerosol optical depth values inside and outside cloud fields reveals differences in the retrieved radiative properties of aerosols depending on their location. The observed mean aerosol optical depth inside the cloud fields is more than 10% higher than outside it, indicating that such convenient cloud field masking may contribute to better estimations of aerosol direct and indirect forcing.

  8. Estimating cloud field coverage using morphological analysis

    International Nuclear Information System (INIS)

    The apparent cloud-free atmosphere in the vicinity of clouds ('the twilight zone') is often affected by undetectable weak signature clouds and humidified aerosols. It is suggested here to classify the atmosphere into two classes: cloud fields, and cloud-free (away from a cloud field), while detectable clouds are included in the cloud field class as a subset. Since the definition of cloud fields is ambiguous, a robust cloud field masking algorithm is presented here, based on the cloud spatial distribution. The cloud field boundaries are calculated then on the basis of the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask products and the total cloud field area is estimated for the Atlantic Ocean (50 deg. S-50 deg. N). The findings show that while the monthly averaged cloud fraction over the Atlantic Ocean during July is 53%, the cloud field fraction may reach 97%, suggesting that cloud field properties should be considered in climate studies. A comparison between aerosol optical depth values inside and outside cloud fields reveals differences in the retrieved radiative properties of aerosols depending on their location. The observed mean aerosol optical depth inside the cloud fields is more than 10% higher than outside it, indicating that such convenient cloud field masking may contribute to better estimations of aerosol direct and indirect forcing.

  9. Experimental single-impulse magnetic focusing of launched cold atoms

    CERN Document Server

    Smith, D A; Hughes, I G; Pritchard, M J; Arnold, Aidan S.; Hughes, Ifan G.; Pritchard, Matthew J.; Smith, David A.

    2007-01-01

    Three-dimensional magnetic focusing of cold atoms with a single magnetic impulse has been observed for the first time. We load 7x10^7 85-Rb atoms into a magneto-optical trap, precool the atoms with optical molasses, then use moving molasses to launch them vertically through 20.5cm to the apex of flight. In transit the atoms are optically pumped, prior to the single magnetic lens impulse that occurs 16.5cm above the MOT. Fluorescence images at the apex of flight characterise the widths of the focussed cloud. Results were obtained for four different configurations of the baseball lens, which tuned the relationship between the axial and radial frequencies of the lens. Compact focused clouds were seen for all four configurations.

  10. G28.17+0.05, A New Type of Cloud in the ISM?

    Science.gov (United States)

    Minter, A. H.; Lockman, F. J.

    2001-05-01

    21 cm HI observations with the NRAO 140 Foot telescope have revealed a giant HI cloud (G28.17+0.05) in the Galactic plane that has unusual properties. The cloud is 150 pc in diameter, is at a distance of 5 kpc, and contains as much as 105 M⊙ of atomic hydrogen. The cloud consists of a cold core, T ~ 40 K, and a hotter outer envelope, T >= 200 K. There is no observable difference in the HI line widths, ~ 7 km s-1, between the core and the envelope. Anomalously-excited 1720 MHz OH emission, with a similar line width, is associated with the core of the cloud. The cloud core also contains 12CO emission which indicates that most of the cloud mass is in molecules. The total mass of the cloud is > 2 x 105 M⊙ . The cloud has only a few sites of current star formation. If similar clouds are associated with other observed sites of anomalously-excited 1720 MHz OH emission, there may be as many as 100 more of these objects in the inner galaxy.

  11. SLA guarantees for cloud services

    OpenAIRE

    Serrano, Damián; Bouchenak, Sara; Kouki, Yousri; Alvares De Oliveira Jr., Frederico; Ledoux, Thomas; Lejeune, Jonathan; Sopena, Julien; Arantes, Luciana; Sens, Pierre

    2016-01-01

    Quality-of-service and SLA guarantees are among the major challenges of cloud-based services. In this paper we first present a new cloud model called SLAaaS — SLA aware Service. SLAaaS considers QoS levels and SLA as first class citizens of cloud-based services. This model is orthogonal to other SaaS, PaaS, and IaaS cloud models, and may apply to any of them. More specifically we make three contributions: (i) we provide a novel domain specific language that allows to describe QoS-oriented SLA...

  12. Cloud/climate sensitivity experiments

    Science.gov (United States)

    Roads, J. O.; Vallis, G. K.; Remer, L.

    1982-01-01

    A study of the relationships between large-scale cloud fields and large scale circulation patterns is presented. The basic tool is a multi-level numerical model comprising conservation equations for temperature, water vapor and cloud water and appropriate parameterizations for evaporation, condensation, precipitation and radiative feedbacks. Incorporating an equation for cloud water in a large-scale model is somewhat novel and allows the formation and advection of clouds to be treated explicitly. The model is run on a two-dimensional, vertical-horizontal grid with constant winds. It is shown that cloud cover increases with decreased eddy vertical velocity, decreased horizontal advection, decreased atmospheric temperature, increased surface temperature, and decreased precipitation efficiency. The cloud field is found to be well correlated with the relative humidity field except at the highest levels. When radiative feedbacks are incorporated and the temperature increased by increasing CO2 content, cloud amounts decrease at upper-levels or equivalently cloud top height falls. This reduces the temperature response, especially at upper levels, compared with an experiment in which cloud cover is fixed.

  13. LINUX BASED CLOUD OPERATING SYSTEM

    Directory of Open Access Journals (Sweden)

    Ravindra Gupta

    2012-02-01

    Full Text Available Cloud computing is a type of computing in which dynamically scalable and virtualized resources are provided as a service. Users need not have knowledge of, expertise in, or control over the technology infrastructure in the cloud that supports them. Furthermore, cloud computing employs a model for enabling available, convenient and on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, services that can be rapidly provisioned and released with minimal management effort or service provider interaction. The services mainly operating systems running on a single virtualized computing environment, middleware layers that attempt to combine physical and virtualized resources from multiple operating systems, and specialized application engines. In this paper, we discuss about the virtual distributed operating system, Cloud Operating System, to provide maximum features of cloud computing. The Cloud Operating System will work on the principle laid out by LINUX. The Cloud OS aims to provide simple programming abstractions to available cloud resources, strong isolation techniques between Cloud processes, and strong integration with network resources.

  14. Cloud computing theory and practice

    CERN Document Server

    Marinescu, Dan C

    2013-01-01

    Cloud Computing: Theory and Practice provides students and IT professionals with an in-depth analysis of the cloud from the ground up. Beginning with a discussion of parallel computing and architectures and distributed systems, the book turns to contemporary cloud infrastructures, how they are being deployed at leading companies such as Amazon, Google and Apple, and how they can be applied in fields such as healthcare, banking and science. The volume also examines how to successfully deploy a cloud application across the enterprise using virtualization, resource management and the ri

  15. Cloud on Linux Operating System

    OpenAIRE

    Pritee Gavhane; Pratibha Kurumkar; Madhuri Jagtap; Dharti Mahajan

    2013-01-01

    The term “cloud” is analyzed to “Internet”. The term “Cloud computing” is based on cloud drawings used in the past to represent telephone networks and later to depict internet. Cloud computing is a internet based computing where virtual shared servers provide software, infrastructure, platform, devices and other resources and hosting to customers on a pay-as-you basis. All information that a digitized system has to offer is a provided as a service in the cloud computing model. Users can acces...

  16. Heroku cloud application development

    CERN Document Server

    Hanjura, Anubhav

    2014-01-01

    An easy-to-follow, hands-on guide that clearly explains the various components of the Heroku platform and provides step-by-step guidance as well as numerous examples on how to build and troubleshoot robust and scalable production-ready web applications on the Heroku platform.This book is intended for those who want to learn Heroku the right way. Perhaps you are new to Heroku or are someone who has heard about Heroku but have not built anything significant with it. You should have knowledge or familiarity with cloud computing and basic knowledge of database and network deployment.

  17. Under that cloud

    OpenAIRE

    O'Hana, Sarah; Lignel , Benjamin; Broadhead, Caroline; Kamata, Jiro; Melland, Nanna; Bloxham, Jo

    2011-01-01

    News that Europe was at a standstill due to the eruption of the Icelandic volcano in April 2010 barely caused a ripple in Mexico City, a land accustomed to living under the threat of its own local Popocatépetl. Momentarily, all that is a given was put on hold under a cloud of surreal paralysis. The enforced, extended stay of some delegates caused by Eyjafjallajökull allowed time to reflect and so to crystallise impressions and perceptions such as the one written by Sam Grainger who reported f...

  18. CLOUD COMPUTING BASED ORIENTATION

    OpenAIRE

    K. Jithendar; K.Srujan Raju; K. Neeraja

    2013-01-01

    With the rapid increase in the technology internet plays a major role in the society with the existence of the cloud based scenario. Where it is very much useful in the technology based on information related to the software oriented approach. It is mainly concerned about the utilities of the system which is the primary goal. It play a key role in the transmission of the data with a high definition oriented security based analysis respectively. Therefore whenever the user in the form of the c...

  19. Mapping in the cloud

    CERN Document Server

    Peterson, Michael P

    2014-01-01

    This engaging text provides a solid introduction to mapmaking in the era of cloud computing. It takes students through both the concepts and technology of modern cartography, geographic information systems (GIS), and Web-based mapping. Conceptual chapters delve into the meaning of maps and how they are developed, covering such topics as map layers, GIS tools, mobile mapping, and map animation. Methods chapters take a learn-by-doing approach to help students master application programming interfaces and build other technical skills for creating maps and making them available on the Internet. Th

  20. Atomic and Molecular Phases of the Interstellar Medium

    CERN Document Server

    Mac Low, Mordecai-Mark

    2016-01-01

    This review covers four current questions in the behavior of the atomic and molecular interstellar medium. These include whether the atomic gas originates primarily in cold streams or hot flows onto galaxies; what the filling factor of cold gas actually is in galactic regions observationally determined to be completely molecular; whether molecular hydrogen determines or merely traces star formation; and whether gravity or turbulence drives the dynamical motions observed in interstellar clouds, with implications on their star formation properties.

  1. Real-time quantum feedback control with cold alkali atoms

    OpenAIRE

    Geremia, J. M.

    2007-01-01

    This chapter describes recent experiments involving continuous measurement and quantum feedback control of collective spin in a cloud of cold alkali atoms. While measurement by itself can generate entanglement between different atoms in the sample by virtue of conditional spin-squeezing, the squeezed state produced in any individual instance of the measurement is randomly distributed. Incorporating real-time feedback control into the observation process suppresses the statistical dispersion o...

  2. Some necessary parameters for a critical velocity interaction between the ionospheric plasma and a xenon cloud

    International Nuclear Information System (INIS)

    The conditions for an experiment to study the critical ionization velocity effect in the interaction between a Xenon cloud, released from a satellite, and the ionospheric plasma are investigated. The model used is based on the assumption that there exists an effective process that transfers the energy, that is available in the relative motion, to the electrons. Some necessary conditions to obtain significant heating or deceleration of the plasma penetrating the cloud are calculated. The conditions are mainly given by the energy available in the relative motion and the rates of the different binary collision processes involved. As the released gas cloud expands the possibilities for a critical velocity interaction will exist only within a certain range of cloud radii. It is shown that the charge transfer collision cross section between the ionospheric ions and the cloud atoms is an important parameter and that Xenon is a very suitable gas in that respect. (author)

  3. The Clouds distributed operating system - Functional description, implementation details and related work

    Science.gov (United States)

    Dasgupta, Partha; Leblanc, Richard J., Jr.; Appelbe, William F.

    1988-01-01

    Clouds is an operating system in a novel class of distributed operating systems providing the integration, reliability, and structure that makes a distributed system usable. Clouds is designed to run on a set of general purpose computers that are connected via a medium-of-high speed local area network. The system structuring paradigm chosen for the Clouds operating system, after substantial research, is an object/thread model. All instances of services, programs and data in Clouds are encapsulated in objects. The concept of persistent objects does away with the need for file systems, and replaces it with a more powerful concept, namely the object system. The facilities in Clouds include integration of resources through location transparency; support for various types of atomic operations, including conventional transactions; advanced support for achieving fault tolerance; and provisions for dynamic reconfiguration.

  4. CloudGenius: Decision Support for Web Server Cloud Migration

    CERN Document Server

    Menzel, Michael

    2012-01-01

    Cloud computing is the latest computing paradigm that delivers hardware and software resources as virtualized services in which users are free from the burden of worrying about the low-level system administration details. Migrating Web applications to Cloud services and integrating Cloud services into existing computing infrastructures is non-trivial. It leads to new challenges that often require innovation of paradigms and practices at all levels: technical, cultural, legal, regulatory, and social. The key problem in mapping Web applications to virtualized Cloud services is selecting the best and compatible mix of software images (e.g., Web server image) and infrastructure services to ensure that Quality of Service (QoS) targets of an application are achieved. The fact that, when selecting Cloud services, engineers must consider heterogeneous sets of criteria and complex dependencies between infrastructure services and software images, which are impossible to resolve manually, is a critical issue. To overcom...

  5. Cloud ERP and Cloud Accounting Software in Romania

    Directory of Open Access Journals (Sweden)

    Gianina MIHAI

    2015-05-01

    Full Text Available Nowadays, Cloud Computing becomes a more and more fashionable concept in the IT environment. There is no unanimous opinion on the definition of this concept, as it covers several versions of the newly emerged stage in the IT. But in fact, Cloud Computing should not suggest anything else than simplicity. Thus, in short, simple terms, Cloud Computing can be defined as a solution to use external IT resources (servers, storage media, applications and services, via Internet. Cloud computing is nothing more than the promise of an easy accessible technology. If the promise will eventually turn into something certain yet remains to be seen. In our opinion it is too early to make an assertion. In this article, our purpose is to find out what is the Romanian offer of ERP and Accounting software applications in Cloud and / or as services in SaaS version. Thus, we conducted an extensive study whose results we’ll present in the following.

  6. Cloud albedo control by cloud-top entrainment

    Science.gov (United States)

    Hanson, Howard P.

    1991-01-01

    Marine stratus and stratocumulus clouds exert a considerable influence on the earth's heat budget, mainly due to their high albedos relative to the ocean surface. It is therefore important to understand the processes that control the radiative properties of these extensive cloud systems, particularly during daylight hours. Aircraft measurements of a stratocumulus cloud deck taken around local noon during the 1987 field phase of the First International Satellite Cloud Climatology Project Regional Experiment are the topic of this paper. A mixing line analysis of data from a series of flight tracks across a strong gradient in cloud albedo provides evidence that variations in the water vapor content of the air above the marine inversion can be responsible for the albedo change. The implications of this unexpected result for climate modeling are discussed.

  7. "Bohr's Atomic Model."

    Science.gov (United States)

    Willden, Jeff

    2001-01-01

    "Bohr's Atomic Model" is a small interactive multimedia program that introduces the viewer to a simplified model of the atom. This interactive simulation lets students build an atom using an atomic construction set. The underlying design methodology for "Bohr's Atomic Model" is model-centered instruction, which means the central model of the…

  8. Growing Cloud Computing Efficiency

    Directory of Open Access Journals (Sweden)

    Dr. Mohamed F. AlAjmi, Dr. Arun Sharma, Shakir Khan

    2012-05-01

    Full Text Available Cloud computing is basically altering the expectation for how and when computing, storage and networking assets should be allocated, managed and devoted. End-users are progressively more sensitive in response time of services they ingest. Service Developers wish for the Service Providers to make sure or give the ability for dynamically assigning and managing resources in respond to alter the demand patterns in real-time. Ultimately, Service Providers are under anxiety to build their infrastructure to facilitate real-time end-to-end visibility and energetic resource management with well grained control to decrease total cost of tenure for improving quickness. What is required to rethink of the underlying operating system and management infrastructure to put up the on-going renovation of data centre from the traditional server-centric architecture model to a cloud or network centric model? This paper projects and describes a indication model for a network centric data centre infrastructure management heap that make use of it and validates key ideas that have enabled dynamism, the quality of being scalable, reliability and security in the telecommunication industry to the computing engineering. Finally, the paper will explain a proof of concept classification that was implemented to show how dynamic resource management can be enforced to enable real-time service guarantee for network centric data centre architecture.

  9. Cooperative Caching Framework for Mobile Cloud Computing

    OpenAIRE

    Joy, Preetha Theresa; Jacob, K. Poulose

    2013-01-01

    Due to the advancement in mobile devices and wireless networks mobile cloud computing, which combines mobile computing and cloud computing has gained momentum since 2009. The characteristics of mobile devices and wireless network makes the implementation of mobile cloud computing more complicated than for fixed clouds. This section lists some of the major issues in Mobile Cloud Computing. One of the key issues in mobile cloud computing is the end to end delay in servicing a request. Data cach...

  10. Interoperability and Standardization of Intercloud Cloud Computing

    OpenAIRE

    Wang, Jingxin K.; Ding, Jianrui; Niu, Tian

    2012-01-01

    Cloud computing is getting mature, and the interoperability and standardization of the clouds is still waiting to be solved. This paper discussed the interoperability among clouds about message transmission, data transmission and virtual machine transfer. Starting from IEEE Pioneering Cloud Computing Initiative, this paper discussed about standardization of the cloud computing, especially intercloud cloud computing. This paper also discussed the standardization from the market-oriented view.

  11. Chemical evolution of molecular clouds

    Science.gov (United States)

    Prasad, Sheo S.; Tarafdar, Sankar P.; Villere, Karen R.; Huntress, Wesley T., Jr.

    1987-01-01

    The principles behind the coupled chemical-dynamical evolution of molecular clouds are described. Particular attention is given to current problems involving the simplest species (i.e., C. CO, O2, and H2) in quiescent clouds. The results of a comparison made between the molecular abundances in the Orion ridge and the hot core (Blake, 1986) are presented.

  12. Cloud computing and services science

    NARCIS (Netherlands)

    Ivanov, Ivan; Sinderen, van Marten; Shishkov, Boris

    2012-01-01

    This book is essentially a collection of the best papers of the International Conference on Cloud Computing and Services Science (CLOSER), which was held in Noordwijkerhout, The Netherlands on May 7–9, 2011. The conference addressed technology trends in the domain of cloud computing in relation to a

  13. Addendum to the CLOUD proposal

    CERN Document Server

    Fastrup, B; Lillestøl, Egil; Thorn, E; Bosteels, Michel; Gonidec, A; Kirkby, Jasper; Mele, S; Minginette, P; Nicquevert, Bertrand; Schinzel, D; Seidl, W; Grundsøe, P; Marsh, N D; Polny, J; Svensmark, H; Viisanen, Y; Kurvinen, K L; Orava, Risto; Hämeri, K; Kulmala, M; Laakso, I; Mäkelä, J M; O'Dowd, C D; Afrosimov, V; Basalaev, A; Panov, M; Laaksonen, B D; Joutsensaari, J; Ermakov, V; Makhmutov, V S; Maksumov, O; Pokrevsky, P; Stozhkov, Yu I; Svirzhevsky, N S; Carslaw, K; Yin, Y; Trautmann, T; Arnold, F; Wohlfrom, K H; Hagen, D; Schmitt, J; Whitefield, P; Aplin, K; Harrison, R G; Bingham, R; Close, Francis Edwin; Gibbins, C; Irving, A; Kellett, B; Lockwood, M; Petersen, D; Szymanski, W W; Wagner, P E; Vrtala, A; CERN. Geneva. SPS-PS Experiments Committee

    2000-01-01

    This report is the first of two addenda to the CLOUD proposal at CERN (physics/0104048), which aims to test experimentally the existence a link between cosmic rays and cloud formation, and to understand the microphysical mechanism. The document provides further details on the detector design, scientific motivation and experimental programme.

  14. Cloud computing assessing the risks

    CERN Document Server

    Carstensen, Jared; Golden, Bernard

    2012-01-01

    Cloud Computing: Assessing the risks answers these questions and many more. Using jargon-free language and relevant examples, analogies and diagrams, it is an up-to-date, clear and comprehensive guide the security, governance, risk, and compliance elements of Cloud Computing.

  15. The ethics of cloud computing

    NARCIS (Netherlands)

    de Bruin, Boudewijn; Floridi, Luciano

    2016-01-01

    Cloud computing is rapidly gaining traction in business. It offers businesses online services on demand (such as Gmail, iCloud and Salesforce) and allows them to cut costs on hardware and IT support. This is the first paper in business ethics dealing with this new technology. It analyzes the informa

  16. How to govern the cloud?

    NARCIS (Netherlands)

    Prüfer, J.; Diamond, S.; Wainwright, N.

    2013-01-01

    This paper applies economic governance theory to the cloud computing industry. We analyze which governance institution may be best suited to solve the problems stemming from asymmetric information about the true level of data protection, security, and accountability offered by cloud service provider

  17. SOME CONSIDERATIONS ON CLOUD ACCOUNTING

    Directory of Open Access Journals (Sweden)

    Doina Pacurari

    2014-01-01

    Full Text Available Cloud technologies have developed intensively during the last years. Cloud computing allows the customers to interact with their data and applications at any time, from any location, while the providers host these resources. A client company may choose to run in the cloud a part of its business (sales by agents, payroll, etc., or even the entire business. The company can get access to a large category of cloud-based software, including accounting software. Cloud solutions are especially recommended for small companies that do not have enough financial resources to invest in the IT infrastructure and in expensive accounting software. However, a special attention is required in the case of sensitive data, which should not be placed in a public cloud. All these aspects need to be discussed with the students, who should acquire the qualifications needed for operating with cloud applications. Our paper considers all the above issues regarding cloud computing for accountants and suggests some possibilities to approach these topics with the students.

  18. Atomic Energy Basics, Understanding the Atom Series.

    Science.gov (United States)

    Atomic Energy Commission, Oak Ridge, TN. Div. of Technical Information.

    This booklet is part of the "Understanding the Atom Series," though it is a later edition and not included in the original set of 51 booklets. A basic survey of the principles of nuclear energy and most important applications are provided. These major topics are examined: matter has molecules and atoms, the atom has electrons, the nucleus,…

  19. Cloud Computing: Exploring the scope

    CERN Document Server

    Pandey, Abhinav; Tandon, Ankit; Maurya, Brajesh Kr; Kushwaha, Upendra

    2010-01-01

    Cloud computing refers a paradigm shift to overall IT solutions while raising the accessibility, scalability and effectiveness through its enabling technologies. However, migrated cloud platforms and services cost benefits as well as performances are neither clear nor summarized. Globalization and the recessionary economic times have not only raised the bar of a better IT delivery models but also have given access to technology enabled services via internet. Cloud computing has vast potential in terms of lean Retail methodologies that can minimize the operational cost by using the third party based IT capabilities, as a service. It will not only increase the ROI but will also help in lowering the total cost of ownership. In this paper we have tried to compare the cloud computing cost benefits with the actual premise cost which an organization incurs normally. However, in spite of the cost benefits, many IT professional believe that the latest model i.e. "cloud computing" has risks and security concerns. This ...

  20. The Future of Cloud Computing

    Directory of Open Access Journals (Sweden)

    Anamaroa SIclovan

    2011-12-01

    Full Text Available

    Cloud computing was and it will be a new way of providing Internet services and computers. This calculation approach is based on many existing services, such as the Internet, grid computing, Web services. Cloud computing as a system aims to provide on demand services more acceptable as price and infrastructure. It is exactly the transition from computer to a service offered
    to the consumers as a product delivered online. This represents an advantage for the organization both regarding the cost and the opportunity for the new business. This paper presents the future perspectives in cloud computing. The paper presents some issues of the cloud computing paradigm. It is a theoretical paper.

    Keywords: Cloud Computing, Pay-per-use

  1. Cloud regimes as phase transitions

    Science.gov (United States)

    Stechmann, Samuel N.; Hottovy, Scott

    2016-06-01

    Clouds are repeatedly identified as a leading source of uncertainty in future climate predictions. Of particular importance are stratocumulus clouds, which can appear as either (i) closed cells that reflect solar radiation back to space or (ii) open cells that allow solar radiation to reach the Earth's surface. Here we show that these clouds regimes -- open versus closed cells -- fit the paradigm of a phase transition. In addition, this paradigm characterizes pockets of open cells as the interface between the open- and closed-cell regimes, and it identifies shallow cumulus clouds as a regime of higher variability. This behavior can be understood using an idealized model for the dynamics of atmospheric water as a stochastic diffusion process. With this new conceptual viewpoint, ideas from statistical mechanics could potentially be used for understanding uncertainties related to clouds in the climate system and climate predictions.

  2. International Satellite Cloud Climatology Project (ISCCP)

    Data.gov (United States)

    National Aeronautics and Space Administration — International Satellite Cloud Climatology Project (ISCCP) focuses on the distribution and variation of cloud radiative properties to improve the understanding of...

  3. Comparison of Cirrus Cloud Models: A Project of the GEWEX Cloud System Study (GCSS) Working Group on Cirrus Cloud Systems

    Science.gov (United States)

    Starr, David OC.; Benedetti, Angela; Boehm, Matt; Brown, Philip R. A.; Gierens, Klaus M.; Girard, Eric; Giraud, Vincent; Jakob, Christian; Jensen, Eric; Khvorostyanov, Vitaly; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The GEWEX Cloud System Study (GCSS, GEWEX is the Global Energy and Water Cycle Experiment) is a community activity aiming to promote development of improved cloud parameterizations for application in the large-scale general circulation models (GCMs) used for climate research and for numerical weather prediction (Browning et al, 1994). The GCSS strategy is founded upon the use of cloud-system models (CSMs). These are "process" models with sufficient spatial and temporal resolution to represent individual cloud elements, but spanning a wide range of space and time scales to enable statistical analysis of simulated cloud systems. GCSS also employs single-column versions of the parametric cloud models (SCMs) used in GCMs. GCSS has working groups on boundary-layer clouds, cirrus clouds, extratropical layer cloud systems, precipitating deep convective cloud systems, and polar clouds.

  4. Secondary laser cooling of strontium-88 atoms

    Energy Technology Data Exchange (ETDEWEB)

    Strelkin, S. A.; Khabarova, K. Yu., E-mail: kseniakhabarova@gmail.com; Galyshev, A. A.; Berdasov, O. I.; Gribov, A. Yu.; Kolachevsky, N. N.; Slyusarev, S. N. [Federal State Unitary Enterprise “All-Russia Research Institute for Physicotechnical and Radio Engineering Measurements” (VNIIFTRI) (Russian Federation)

    2015-07-15

    The secondary laser cooling of a cloud of strontium-88 atoms on the {sup 1}S{sub 0}–{sup 3}P{sub 1} (689 nm) intercombination transition captured into a magneto-optical trap has been demonstrated. We describe in detail the recapture of atoms from the primary trap operating on the strong {sup 1}S{sub 0}–{sup 1}P{sub 1} (461 nm) transition and determine the recapture coefficient κ, the number of atoms, and their temperature in the secondary trap as a function of experimental parameters. A temperature of 2 µK has been reached in the secondary trap at the recapture coefficient κ = 6%, which confirms the secondary cooling efficiency and is sufficient to perform metrological measurements of the {sup 1}S{sub 0}–{sup 3}P{sub 1} (698 nm) clock transition in an optical lattice.

  5. Realization of Green MOT for Ytterbium Atoms

    Institute of Scientific and Technical Information of China (English)

    ZHAO Peng-Yi; XIONG Zhuan-Xian; LONG Yun; HE Ling-Xiang; L(U) Bao-Long

    2009-01-01

    We report the experimental realization of a magneto-optical trap (MOT) of 174Yb atoms operating on the 1S0-3p1 intercombination transition at 555.8 nm.The green MOT is loaded by a Zeeman-slowed atomic beam.In order to increase the capture velocity of the MOT,we use the trapping laser beams consisting of five discrete frequency components obtained by modulating the laser light through an electro-optic modulator.The trapped atomic number of the 174 Yb isotope is about 6.2×105,and the temperature of the cold atowic cloud is estimated to be about 100 μK.The success of the green MOT is an important step towards the goad of an ytterbium optical dock.

  6. Teach us atom structure

    International Nuclear Information System (INIS)

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  7. Teach us atom structure

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Suh Yeon

    2006-08-15

    This book is written to teach atom structure in very easy way. It is divided into nine chapters, which indicates what is the components of matter? when we divide matter continuously, it becomes atom, what did atom look like? particles comprised of matter is not only atom, discover of particles comprised of atom, symbol of element, various radiation, form alchemy to nuclear transmutation, shape of atom is evolving. It also has various pictures in each chapters to explain easily.

  8. EDITORIAL: Focus on Cloud Physics FOCUS ON CLOUD PHYSICS

    Science.gov (United States)

    Falkovich, Gregory; Malinowski, Szymon P.

    2008-07-01

    Cloud physics has for a long time been an important segment of atmospheric science. It is common knowledge that clouds are crucial for our understanding of weather and climate. Clouds are also interesting by themselves (not to mention that they are beautiful). Complexity is hidden behind the common picture of these beautiful and interesting objects. The typical school textbook definition that a cloud is 'a set of droplets or particles suspended in the atmosphere' is not adequate. Clouds are complicated phenomena in which dynamics, turbulence, microphysics, thermodynamics and radiative transfer interact on a wide range of scales, from sub-micron to kilometres. Some of these interactions are subtle and others are more straightforward. Large and small-scale motions lead to activation of cloud condensation nuclei, condensational growth and collisions; small changes in composition and concentration of atmospheric aerosol lead to significant differences in radiative properties of the clouds and influence rainfall formation. It is justified to look at a cloud as a composite, nonlinear system which involves many interactions and feedback. This system is actively linked into a web of atmospheric, oceanic and even cosmic interactions. Due to the complexity of the cloud system, present-day descriptions of clouds suffer from simplifications, inadequate parameterizations, and omissions. Sometimes the most fundamental physics hidden behind these simplifications and parameterizations is not known, and a wide scope of view can sometimes prevent a 'microscopic', deep insight into the detail. Only the expertise offered by scientists focused on particular elementary processes involved in this complicated pattern of interactions allows us to shape elements of the puzzle from which a general picture of clouds can be created. To be useful, every element of the puzzle must be shaped precisely. This often creates problems in communication between the sciences responsible for shaping

  9. Controllable Magnetic Focusing of Cold Atoms on a Chip

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; YUN Min; YIN Jian-Ping

    2006-01-01

    @@ We propose a new lens scheme to focus cold atoms by using a controllable inhomogeneous magnetic field from a square current-carrying wire fabricated on a chip. The spatial distributions of the magnetic field are calculated, and the results show that the generated magnetic field is a two-dimensional (2D) quadrupole one and can be used to focus cold atoms or a cold atomic beam. The dynamic processes of cold atoms passing through our square wire layout and its focusing properties are studied by using Monte Carlo simulations. Our study shows that the atomic clouds can be focused effectively by our magnetic lens scheme, and the focal lengthof the atomic lens and its radius of focused spot can be continuously changed by adjusting the current in the wires.

  10. 浊点萃取-流动注射电感耦合等离子体原子发射光谱法同时测定水中镉钴铜镍锌%Simultaneous Determination of Cadmium, Cobalt,Copper, Nickel and Zinc in Water Samples by Flow Injection-Inductively Coupled Plasma-Atomic Emission Spectrometry after Cloud Point Extraction

    Institute of Scientific and Technical Information of China (English)

    陈建国; 陈恒武; 金献忠; 陈海婷

    2009-01-01

    A cloud point extraction procedure was developed for pre-concentration of trace amount of Cd2+, Co2+,Cu2+, Ni2+ and Zn2+ in water samples prior to inductively coupled plasma atomic emission spectrometric determination. 5-Br-PADAP was used to transform the metal ions into water in-soluble chelates, and the chelates were extracted into a surfactant-rich phase of Triton X-114. After being diluted with ethanol-nitric acid solution, the surfactant-rich phase containing the concentrated metal ions was introduced into the ICP with flow injection technique. Various experimental conditions such as sampling volume, integration time, extraction acidity and concentrations of 5-Br-PADAP and Triton X-114 were examined. Under the optimized conditions, enhancement factors of 18, 10, 16, 10, 8 and detection limits of 0.7, 1.6, 1.3, 5.7, and 3.2 g/L were obtained for Cd2+, Co2+,Cu2+, Ni2+ and Zn2+, respectively. The developed method was successfully applied to the determination of Cd2+, Co2+,Cu2+, Ni2+ and Zn2+ in tap water, river water and sea water samples. Recoveries for the spiked samples were in the range of 80% and 118%.%本文提出了浊点萃取-流动注射电感耦合等离子体原子发射光谱(FI-ICP-AES)法同时测定水中镉、钴、铜、镍、锌的新方法.利用5-Br-PADAP将待测金属离子转化为水不溶性的螯合物,并萃取到表面活性剂Triton X-114的浓缩相,以乙醇-硝酸溶液稀释含富集离子的浓缩相,并以FI-ICP-AES法测定.考察了流动注射进样体积、积分时间、萃取体系介质酸度、螯合剂和表面活性剂用量等实验条件的影响.在折衷条件下,镉、钴、铜、镍和锌的浓缩倍率可达18、10、16、10和8,检出限分别为0.7 μg/L、1.6 μg/L、1.3 μg/L、5.7 μg/L、3.2 μg/L.方法成功应用于自来水、河水和海水中痕量镉、钴、铜、镍和锌的分析.在0.02 mg/L 和0.10 mg/L二个水平进行加入回收试验,回收率在80%与118%之间.

  11. Box-Behnken设计优化浊点萃取-原子荧光光谱法测定中药材中的汞%Cloud Point Extraction for Determination of Mercury in Chinese Herbal Medicine by Hydride Generation Atomic Fluorescence Spectrometry with Optimization Using Box-Behnken Design

    Institute of Scientific and Technical Information of China (English)

    王梅; 李姗; 周建栋; 徐英; 龙军标; 杨冰仪

    2014-01-01

    Cloud point extraction (CPE)is proposed as a pre-concentration procedure for the determination of Hg in Chinese herbal medicine samples by hydride generation-atomic fluorescence spectrometry (HG-AFS).Hg2+ was reacted with dithizone to form hydrophobic chelate under the condition of pH.Using Triton X-114,as surfactant,chelate was quantitatively extracted in-to small volume of the surfactant-rich phase by heating the solution in a water bath for 15 min and centrifuging.Four variables including pH,dithizone concentration,Triton X-114 concentration and equilibrium temperature (T)showed the significant effect on extraction efficiency of total Hg evaluated by single-factor experiment,and Box-Behnken design and response surface method-ology were adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum extraction efficiency.The results showed that the binomial was used to fit the response to experimental levels of each variable.ALL linear,quadratic terms of four variables,and interactions between pH and Trion X-114,pH and di-thizone affected the response value(extraction efficiency)significantly at 5% level.The optimum extraction conditions were as follows:pH 5. 1,Triton X-114 concentration of 1. 16 g·L-1 ,dithizone concentration of 4. 87 mol·L-1 ,and T 58. 2 ℃,the predicted value of fluorescence was 4 528. 74 under the optimum conditions,and the experimental value had only 2. 1%difference with it.Under the conditions,fluorescence was linear to mercury concentration in the range of 1~5μg·L-1 .The limit of de-tection obtained was 0. 012 47 μg·L-1 with the relative standard deviations (R.S.D.)for six replicate determinations of 1. 30%.The proposed method was successfully applied to determination of Hg in morindae Radix,Andrographitis and dried tan-gerine samples with the recoveries of 95. 0%~100. 0%.Apparently Box- Behnken design combined with response surface anal-ysis method was

  12. Constraining the Properties of Cold Interstellar Clouds

    Science.gov (United States)

    Spraggs, Mary Elizabeth; Gibson, Steven J.

    2016-01-01

    Since the interstellar medium (ISM) plays an integral role in star formation and galactic structure, it is important to understand the evolution of clouds over time, including the processes of cooling and condensation that lead to the formation of new stars. This work aims to constrain and better understand the physical properties of the cold ISM by utilizing large surveys of neutral atomic hydrogen (HI) 21cm spectral line emission and absorption, carbon monoxide (CO) 2.6mm line emission, and multi-band infrared dust thermal continuum emission. We identify areas where the gas may be cooling and forming molecules using HI self-absorption (HISA), in which cold foreground HI absorbs radiation from warmer background HI emission.We are developing an algorithm that uses total gas column densities inferred from Planck and other FIR/sub-mm data in parallel with CO and HISA spectral line data to determine the gas temperature, density, molecular abundance, and other properties as functions of position. We can then map these properties to study their variation throughout an individual cloud as well as any dependencies on location or environment within the Galaxy.Funding for this work was provided by the National Science Foundation, the NASA Kentucky Space Grant Consortium, the WKU Ogden College of Science and Engineering, and the Carol Martin Gatton Academy for Mathematics and Science in Kentucky.

  13. Photogrammetry and photo interpretation applied to analyses of cloud cover, cloud type, and cloud motion

    Science.gov (United States)

    Larsen, P. A.

    1972-01-01

    A determination was made of the areal extent of terrain obscured by clouds and cloud shadows on a portion of an Apollo 9 photograph at the instant of exposure. This photogrammetrically determined area was then compared to the cloud coverage reported by surface weather observers at approximately the same time and location, as a check on result quality. Stereograms prepared from Apollo 9 vertical photographs, illustrating various percentages of cloud coverage, are presented to help provide a quantitative appreciation of the degradation of terrain photography by clouds and their attendant shadows. A scheme, developed for the U.S. Navy, utilizing pattern recognition techniques for determining cloud motion from sequences of satellite photographs, is summarized. Clouds, turbulence, haze, and solar altitude, four elements of our natural environment which affect aerial photographic missions, are each discussed in terms of their effects on imagery obtained by aerial photography. Data of a type useful to aerial photographic mission planners, expressing photographic ground coverage in terms of flying height above terrain and camera focal length, for a standard aerial photograph format, are provided. Two oblique orbital photographs taken during the Apollo 9 flight are shown, and photo-interpretations, discussing the cloud types imaged and certain visible geographical features, are provided.

  14. Atomic phase diagram

    Institute of Scientific and Technical Information of China (English)

    LI Shichun

    2004-01-01

    Based on the Thomas-Fermi-Dirac-Cheng model, atomic phase diagram or electron density versus atomic radius diagram describing the interaction properties of atoms of different kinds in equilibrium state is developed. Atomic phase diagram is established based on the two-atoms model. Besides atomic radius, electron density and continuity condition for electron density on interfaces between atoms, the lever law of atomic phase diagram involving other physical parameters is taken into account, such as the binding energy, for the sake of simplicity.

  15. Clouds of deceit

    International Nuclear Information System (INIS)

    The full story of Britain's nuclear weapons tests in the 1950s has only recently begun to emerge. Here, for the first time, through interviews and eye-witness accounts from men who watched the mushroom clouds drift over Australia and the Pacific Ocean, the tests are vividly recreated. Using official documents recently made public, evidence gathered by the Australian government's Royal Commission of Inquiry into the tests, and her own experience as an investigative journalist, the author argues forcefully that the bomb tests are far from being a historical anecdote. They remain with us in the shape of the victims -servicemen, civilians and aborigines who witnessed them - and through Britain's continuing programme of nuclear weapons tests in the United States. In this disturbing and horrific book the author raises crucial questions about the British government's responsibility to the people who took part in the tests - and shows how their effects may yet have a devastating impact on Britain's nuclear industry. (author)

  16. Cloud Security A Comprehensive Guide to Secure Cloud Computing

    CERN Document Server

    Krutz, Ronald L

    2010-01-01

    Well-known security experts decipher the most challenging aspect of cloud computing-security. Cloud computing allows for both large and small organizations to have the opportunity to use Internet-based services so that they can reduce start-up costs, lower capital expenditures, use services on a pay-as-you-use basis, access applications only as needed, and quickly reduce or increase capacities. However, these benefits are accompanied by a myriad of security issues, and this valuable book tackles the most common security challenges that cloud computing faces. The authors offer you years of unpa

  17. Evolution of Cloud Storage as Cloud Computing Infrastructure Service

    OpenAIRE

    Rajan, Arokia Paul; Shanmugapriyaa

    2013-01-01

    Enterprises are driving towards less cost, more availability, agility, managed risk - all of which is accelerated towards Cloud Computing. Cloud is not a particular product, but a way of delivering IT services that are consumable on demand, elastic to scale up and down as needed, and follow a pay-for-usage model. Out of the three common types of cloud computing service models, Infrastructure as a Service (IaaS) is a service model that provides servers, computing power, network bandwidth and S...

  18. Atomizer design for viscous-melt atomization

    Energy Technology Data Exchange (ETDEWEB)

    Czisch, C. [Chemical Engineering Department, University Bremen, Badgasteiner Str. 3, 28359 Bremen (Germany); Fritsching, U. [Chemical Engineering Department, University Bremen, Badgasteiner Str. 3, 28359 Bremen (Germany)], E-mail: ufri@iwt.uni-bremen.de

    2008-03-25

    The development of a gas atomization unit is introduced, which utilizes characteristic flow effects for efficient fragmentation of viscous liquids and melts. The proposed device combines a classical rotary atomizer with an external mixing gas atomizer. Here, the liquid stream is first transformed into a thin liquid sheet before disintegration. Thereby the specific surface energy is increased without breakup. The movement of the free flowing liquid film is controlled by the local gas flow field in order to transport the film into the most effective atomization region. The fragmentation process itself is caused by a perpendicular impinging gas stream. Numerical flow simulations are used for the development of the hybrid atomizer construction. Experiments using viscous model liquids show that for constant air-to-liquid mass-flow ratio the particle size is reduced using the hybrid atomizer compared with a conventional gas atomizer. Results of model experiments as well as of experiments with a viscous mineral melt are discussed.

  19. Atomizer design for viscous-melt atomization

    International Nuclear Information System (INIS)

    The development of a gas atomization unit is introduced, which utilizes characteristic flow effects for efficient fragmentation of viscous liquids and melts. The proposed device combines a classical rotary atomizer with an external mixing gas atomizer. Here, the liquid stream is first transformed into a thin liquid sheet before disintegration. Thereby the specific surface energy is increased without breakup. The movement of the free flowing liquid film is controlled by the local gas flow field in order to transport the film into the most effective atomization region. The fragmentation process itself is caused by a perpendicular impinging gas stream. Numerical flow simulations are used for the development of the hybrid atomizer construction. Experiments using viscous model liquids show that for constant air-to-liquid mass-flow ratio the particle size is reduced using the hybrid atomizer compared with a conventional gas atomizer. Results of model experiments as well as of experiments with a viscous mineral melt are discussed

  20. Cold Matter Assembled Atom-by-Atom

    CERN Document Server

    Endres, Manuel; Keesling, Alexander; Levine, Harry; Anschuetz, Eric R; Krajenbrink, Alexandre; Senko, Crystal; Vuletic, Vladan; Greiner, Markus; Lukin, Mikhail D

    2016-01-01

    The realization of large-scale fully controllable quantum systems is an exciting frontier in modern physical science. We use atom-by-atom assembly to implement a novel platform for the deterministic preparation of regular arrays of individually controlled cold atoms. In our approach, a measurement and feedback procedure eliminates the entropy associated with probabilistic trap occupation and results in defect-free arrays of over 50 atoms in less than 400 ms. The technique is based on fast, real-time control of 100 optical tweezers, which we use to arrange atoms in desired geometric patterns and to maintain these configurations by replacing lost atoms with surplus atoms from a reservoir. This bottom-up approach enables controlled engineering of scalable many-body systems for quantum information processing, quantum simulations, and precision measurements.

  1. Compression as a tool to detect Bose glass in cold atoms experiments

    OpenAIRE

    Delande, Dominique; Zakrzewski, Jakub

    2008-01-01

    We suggest that measuring the variation of the radius of an atomic cloud when the harmonic tap confinement is varied make it possible to monitor the disappearance of the insulating Mott phase of an ultracold atomic gas trapped in a disordered optical lattice. This paves the way for an unambiguous identification of a Bose glass phase in the system.

  2. Kicking atoms with finite duration pulses

    Science.gov (United States)

    Fekete, Julia; Chai, Shijie; Daszuta, Boris; Andersen, Mikkel F.

    2016-05-01

    The atom optics delta-kicked particle is a paradigmatic system for experimental studies of quantum chaos and classical-quantum correspondence. It consists of a cloud of laser cooled atoms exposed to a periodically pulsed standing wave of far off-resonant laser light. A purely quantum phenomena in such systems are quantum resonances which transfers the atoms into a coherent superposition of largely separated momentum states. Using such large momentum transfer ``beamsplitters'' in atom interferometers may have applications in high precision metrology. The growth in momentum separation cannot be maintained indefinitely due to finite laser power. The largest momentum transfer is achieved by violating the usual delta-kick assumption. Therefore we explore the behavior of the atom optics kicked particle with finite pulse duration. We have developed a semi-classical model which shows good agreement with the full quantum description as well as our experiments. Furthermore we have found a simple scaling law that helps to identify optimal parameters for an atom interferometer. We verify this by measurements of the ``Talbot time'' (a measurement of h/m) which together with other well-known constants constitute a measurement of the fine structure constant.

  3. Dense cloud cores revealed by CO in the low metallicity dwarf galaxy WLM.

    Science.gov (United States)

    Rubio, Monica; Elmegreen, Bruce G; Hunter, Deidre A; Brinks, Elias; Cortés, Juan R; Cigan, Phil

    2015-09-10

    Understanding stellar birth requires observations of the clouds in which they form. These clouds are dense and self-gravitating, and in all existing observations they are molecular, with H2 the dominant species and carbon monoxide (CO) the best available tracer. When the abundances of carbon and oxygen are low compared with that of hydrogen, and the opacity from dust is also low, as in primeval galaxies and local dwarf irregular galaxies, CO forms slowly and is easily destroyed, so it is difficult for it to accumulate inside dense clouds. Here we report interferometric observations of CO clouds in the local group dwarf irregular galaxy Wolf-Lundmark-Melotte (WLM), which has a metallicity that is 13 per cent of the solar value and 50 per cent lower than the previous CO detection threshold. The clouds are tiny compared to the surrounding atomic and H2 envelopes, but they have typical densities and column densities for CO clouds in the Milky Way. The normal CO density explains why star clusters forming in dwarf irregulars have similar densities to star clusters in giant spiral galaxies. The low cloud masses suggest that these clusters will also be low mass, unless some galaxy-scale compression occurs, such as an impact from a cosmic cloud or other galaxy. If the massive metal-poor globular clusters in the halo of the Milky Way formed in dwarf galaxies, as is commonly believed, then they were probably triggered by such an impact. PMID:26354481

  4. Rethinking a Mysterious Molecular Cloud

    CERN Document Server

    Imara, Nia

    2015-01-01

    I present high-resolution column density maps of two molecular clouds having strikingly different star formation rates. To better understand the unusual, massive G216-2.5, a molecular cloud with no massive star formation, the distribution of its molecular gas is compared to that of the Rosette Molecular Cloud. Far-infrared data from Herschel are used to derive $N(\\mathrm{H}_2)$ maps of each cloud and are combined with $I_{\\mathrm{CO}}$ data to determine the CO-to-H$_2$ ratio, $X_{\\mathrm{CO}}$. In addition, the probability distribution functions (PDFs) and cumulative mass fractions of the clouds are compared. For G216-2.5, $=7.8\\times 10^{20} cm^{-2}$ and $ =2.2\\times 10^{20} (K km s^{-1})^{-1}$; for the Rosette, $ =1.8\\times 10^{21} cm^{-2}$ and $ =2.8\\times 10^{20} (K km s^{-1})^{-1}$. The PDFs of both clouds are log-normal for extinctions below $\\sim 2$ mag and both show departures from log-normality at high extinctions. Although it is the less-massive cloud, the Rosette has a higher fraction of its mass ...

  5. ATLAS Cloud R&D

    CERN Document Server

    Panitkin, S; The ATLAS collaboration; Caballero Bejar, J; Benjamin, D; DiGirolamo, A; Gable, I; Hendrix, V; Hover, J; Kucharczuk, K; Medrano LLamas, R; Love, P; Ohman, H; Paterson, M; Sobie, R; Taylor, R; Walker, R; Zaytsev, A

    2014-01-01

    The computing model of the ATLAS experiment was designed around the concept of grid computing and, since the start of data taking, this model has proven very successful. However, new cloud computing technologies bring attractive features to improve the operations and elasticity of scientific distributed computing. ATLAS sees grid and cloud computing as complementary technologies that will coexist at different levels of resource abstraction, and two years ago created an R&D working group to investigate the different integration scenarios. The ATLAS Cloud Computing R&D has been able to demonstrate the feasibility of offloading work from grid to cloud sites and, as of today, is able to integrate transparently various cloud resources into the PanDA workload management system. The ATLAS Cloud Computing R&D is operating various PanDA queues on private and public resources and has provided several hundred thousand CPU days to the experiment. As a result, the ATLAS Cloud Computing R&D group has gained...

  6. World of Cloud Computing & Security

    Directory of Open Access Journals (Sweden)

    Ashish Kumar

    2012-06-01

    Full Text Available Cloud computing promises to increase the velocity with which application are deployed, increase innovation and lower costs, all while increasing business agility and hence envisioned as the next generation architecture of IT Enterprise. Nature of cloud computing builds an established trend for driving cost out of the delivery of services while increasing the speed and agility with which services are deployed. Cloud Computing incorporates virtualization, on demand deployment, Internet delivery of services and open source software .From another perspective, everything is new because cloud computing changes how we invent, develop, deploy, scale, update, maintain and pay for application and the infrastructure on which they run. Because of these benefits of Cloud Computing, it requires an effective and flexible dynamic security scheme to ensure the correctness of users’ data in the cloud. Quality of service is an important aspect and hence, extensive cloud data security and performance is required. Normal 0 false false false EN-US X-NONE X-NONE ashish.kumar@bharatividyapeeth.edu

  7. Chemical composition of Venus clouds

    Science.gov (United States)

    Krasnopolsky, V. A.

    1985-01-01

    From estimates of drying effect in the cloud layer, data of the Venera 14 X-ray fluorescent spectroscopy, and evaluation of photochemical production of sulfuric acid, it follows that sulfuric acid and/or products of its further conversion should constitute not only the Mode 2 particles but most of the Mode 3 particles as well. The eddy mixing coefficient equal 20,000 sq cm per sec in the cloud layer. The presence of ferric chloride in the cloud layer is indicated by the Venus u.v. absorption spectrum in the range of 3200-5000 A, by the Venera 12 X-ray fluorescent spectrum, by the coincidence of the calculated FeCl3 condensate density profile and that of the Mode 1 in the middle and lower cloud layer, as well as by the upward flux of FeCl3 from the middle cloud layer which provides the necessary concentration of FeCl3 in H2SO4 solution. FeCl3 as the second absorber explains the localization of absorption in the upper cloud layer due to the FeCl3 conversion to ferric sulfate near the boundary between the upper and middle cloud layers. Other possible absorbers such as sulfur, ammonium pyrosulfite, nitrosylsulfuric acid, etc. are discussed.

  8. Shaking-induced dynamics of cold atoms in magnetic traps

    CERN Document Server

    García, I Llorente; Sinclair, C D J; Curtis, E A; Tachikawa, M; Hudson, J J; Hinds, E A

    2013-01-01

    We describe an experiment in which cold rubidium atoms, confined in an elongated magnetic trap, are excited by transverse oscillation of the trap centre. The temperature after excitation exhibits resonance as a function of the driving frequency. We measure these resonances at several different trap frequencies. In order to interpret the experiments, we develop a simple model that incorporates both collisions between atoms and the anharmonicity of the real three-dimensional trapping potential. As well as providing a precise connection between the transverse harmonic oscillation frequency and the temperature resonance frequency, this model gives insight into the heating and loss mechanisms, and into the dynamics of driven clouds of cold trapped atoms.

  9. Measurement of the Gravity-Field Curvature by Atom Interferometry

    CERN Document Server

    Rosi, G; Sorrentino, F; Menchetti, M; Prevedelli, M; Tino, G M

    2015-01-01

    We present the first direct measurement of the gravity-field curvature based on three conjugated atom interferometers. Three atomic clouds launched in the vertical direction are simultaneously interrogated by the same atom interferometry sequence and used to probe the gravity field at three equally spaced positions. The vertical component of the gravity-field curvature generated by nearby source masses is measured from the difference between adjacent gravity gradient values. Curvature measurements are of interest in geodesy studies and for the validation of gravitational models of the surrounding environment. The possibility of using such a scheme for a new determination of the Newtonian constant of gravity is also discussed.

  10. Slow polaritons with orbital angular momentum in atomic gases

    OpenAIRE

    Ruseckas J.; Mekys A.; Juzeliunas G.

    2011-01-01

    Polariton formalism is applied for studying the propagation of a probe field of light in a cloud of cold atoms influenced by two control laser beams of larger intensity. The laser beams couple resonantly three hyperfine atomic ground states to a common excited state thus forming a tripod configuration of the atomic energy levels involved. The first control beam can have an optical vortex with the intensity of the beam going to zero at the vortex core. The second control beam without a vortex ...

  11. Spin Hall separation of ultracold atom-molecule mixed gases

    Science.gov (United States)

    Ye, Chong; Fu, Li-Bin; Liu, Jie

    2016-05-01

    We propose a theoretical scheme to separate a molecular cloud from atoms in analogy to the spin Hall effect and to completely transfer Feshbach molecules to the ground state by applying a spatially modulated laser field to an atom-molecule mixed gas. In particular, the laser-molecule interaction induces a synthetic U(1) gauge potential for the dressed molecular dark state. Through numerical simulation, we demonstrate that such a gauge field leads to a spin Hall separation of atoms and molecules. In such a process, molecules can be transformed into the ground state completely.

  12. Photoionization of ultracold and Bose-Einstein-condensed Rb atoms

    International Nuclear Information System (INIS)

    Photoionization of a cold atomic sample offers intriguing possibilities for observing collective effects at extremely low temperatures. Irradiation of a rubidium condensate and of cold rubidium atoms within a magneto-optical trap (MOT) with laser pulses ionizing through one-photon and two-photon absorption processes was performed. Losses and modifications in the density profile of the remaining trapped cold cloud or the remaining condensate sample were examined as functions of the ionizing laser parameters. Ionization cross sections were measured for atoms in a MOT, while in magnetic traps losses larger than those expected for ionization process were measured

  13. Cloud computing for enterprise architectures

    CERN Document Server

    Mahmood, Zaigham

    2011-01-01

    This important text provides a single point of reference for state-of-the-art cloud computing design and implementation techniques. The book examines cloud computing from the perspective of enterprise architecture, asking the question; how do we realize new business potential with our existing enterprises? Its topics and features are: with a Foreword by Thomas Erl; contains contributions from an international selection of preeminent experts; presents the state-of-the-art in enterprise architecture approaches with respect to cloud computing models, frameworks, technologies, and applications; di

  14. Increasing Security in Cloud Environment

    OpenAIRE

    Naik, Priyanka; Sanyal, Sugata

    2013-01-01

    The concept of cloud computing was introduced to meet the increase in demand for new application for a project, and to provide a large storage facility whenever or wherever a user needs it. The cloud system facility helped many industries as well as individual users to get authentic software at a very low cost. But with this new system comes the major concern of security, as the connection to the cloud is through the web and the data and application availability need to be handled for each cl...

  15. Mobile Cloud Computing and Applications

    Institute of Scientific and Technical Information of China (English)

    Chengzhong Xu

    2011-01-01

    @@ In 2010, cloud computing gained momentum.Cloud computing is a model for real-time, on-demand, pay-for-use network access to a shared pool of configurable computing and storage resources.It has matured from a promising business concept to a working reality in both the private and public IT sectors.The U.S.government, for example, has requested all its agencies to evaluate cloud computing alternatives as part of their budget submissions for new IT investment.

  16. Service Brokering in Cloud Computing

    OpenAIRE

    Holmen, Mari; Braaten, Sindre Møgster

    2014-01-01

    AbstractWith the expanding cloud computing market new business models take form, and the focus in the market is on differentiation and adapting to the escalating demands of the customers. To satisfy the business segment of the market the offering of some quality of service (QoS) measures and guarantees is paramount. The next generation of brokers will be the QoS-aware brokers with cloud connectivity.This thesis regards the decisions of a combined broker and carrier in a cloud computing ecosys...

  17. Cloud Thickness from Diffusion of Lidar Pulses in Clouds

    Science.gov (United States)

    Cahalan, Robert F.; Davis, A.; McGill, Matthew

    1999-01-01

    Measurements of the distribution of reflected light from a laser beam incident on an aqueous suspension of particles or "cloud" with known thickness and particle size distribution are reported. The distribution is referred to as the "cloud radiative Green's function", G. In the diffusion domain, G is sensitive to cloud thickness, allowing that important quantity to be retrieved. The goal of the laboratory simulation is to provide preliminary estimates of sensitivity of G to cloud thickness,for use in the optimal design of an offbeam Lidar instrument for remote sensing of cloud thickness (THOR, Thickness from Offbeam Returns). These clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The microsphere size distribution is roughly lognormal, from 0.5 microns to 25 microns, similar to real clouds. Density of suspended spheres is adjusted so mean-free-path of visible photons is about 10 cm, approximately 1000 times smaller than in real clouds. The light source is a ND:YAG laser at 530 nm. Detectors are flux and photon-counting Photomultiplier Tube (PMTS), with a glass probe for precise positioning. A Labview 5 VI controls positioning, and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider, and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns, and step size is selectable from the VI software. Far from the incident beam, the rate of exponential increase as the direction of the incident beam is approached scales as expected from diffusion theory, linearly with the cloud thickness, and inversely as the square root of the reduced optical thickness, and is independent of particle size. Near the beam the signal begins to increase faster than exponential, due to single and low-order scattering near the backward direction, and here the distribution depends on particle size. Results are being used to verify 3D Monte Carlo

  18. Controlling Rydberg atom excitations in dense background gases

    CERN Document Server

    Liebisch, Tara Cubel; Engel, Felix; Nguyen, Huan; Balewski, Jonathan; Lochead, Graham; Böttcher, Fabian; Westphal, Karl M; Kleinbach, Kathrin S; Schmid, Thomas; Gaj, Anita; Löw, Robert; Hofferberth, Sebastian; Pfau, Tilman; Pérez-Ríos, Jesús; Greene, Chris H

    2016-01-01

    We discuss the density shift and broadening of Rydberg spectra measured in cold, dense atom clouds in the context of Rydberg atom spectroscopy done at room temperature, dating back to the experiments of Amaldi and Segr\\`e in 1934. We discuss the theory first developed in 1934 by Fermi to model the mean-field density shift and subsequent developments of the theoretical understanding since then. In particular, we present a model whereby the density shift is calculated using a microscopic model in which the configurations of the perturber atoms within the Rydberg orbit are considered. We present spectroscopic measurements of a Rydberg atom, taken in a Bose-Einstein condensate (BEC) and thermal clouds with densities varying from $5\\times10^{14}\\textrm{cm}^{-3}$ to $9\\times10^{12}\\textrm{cm}^{-3}$. The density shift measured via the spectrum's center of gravity is compared with the mean-field energy shift expected for the effective atom cloud density determined via a time of flight image. Lastly, we present calcul...

  19. Cloud Computing:Strategies for Cloud Computing Adoption

    OpenAIRE

    Shimba, Faith

    2010-01-01

    The advent of cloud computing in recent years has sparked an interest from different organisations, institutions and users to take advantage of web applications. This is a result of the new economic model for the Information Technology (IT) department that cloud computing promises. The model promises a shift from an organisation required to invest heavily for limited IT resources that are internally managed, to a model where the organisation can buy or rent resources that are managed by a clo...

  20. Hidden in the Clouds: New Ideas in Cloud Computing

    CERN Document Server

    CERN. Geneva

    2013-01-01

    Abstract: Cloud computing has become a hot topic. But 'cloud' is no newer in 2013 than MapReduce was in 2005: We've been doing both for years. So why is cloud more relevant today than it ever has been? In this presentation, we will introduce the (current) central thesis of cloud computing, and explore how and why (or even whether) the concept has evolved. While we will cover a little light background, our primary focus will be on the consequences, corollaries and techniques introduced by some of the leading cloud developers and organizations. We each have a different deployment model, different applications and workloads, and many of us are still learning to efficiently exploit the platform services offered by a modern implementation. The discussion will offer the opportunity to share these experiences and help us all to realize the benefits of cloud computing to the fullest degree. Please bring questions and opinions, and be ready to share both!   Bio: S...

  1. Secure Data Sharing in Cloud Computing using Hybrid cloud

    Directory of Open Access Journals (Sweden)

    Er. Inderdeep Singh

    2015-06-01

    Full Text Available Cloud computing is fast growing technology that enables the users to store and access their data remotely. Using cloud services users can enjoy the benefits of on-demand cloud applications and data with limited local infrastructure available with them. While accessing the data from cloud, different users may have relationship among them depending on some attributes, and thus sharing of data along with user privacy and data security becomes important to get effective results. Most of the research has been done to secure the data authentication so that user’s don’t lose their private data stored on public cloud. But still data sharing is a significant hurdle to overcome by researchers. Research is going on to provide secure data sharing with enhanced user privacy and data access security. In this paper various research and challenges in this area are discussed in detail. It will definitely help the cloud users to understand the topic and researchers to develop a method to overcome these challenges.

  2. Continuous growth of cloud droplets in cumulus cloud

    Science.gov (United States)

    Gotoh, Toshiyuki; Suehiro, Tamotsu; Saito, Izumi

    2016-04-01

    A new method to seamlessly simulate the continuous growth of droplets advected by turbulent flow inside a cumulus cloud was developed from first principle. A cubic box ascending with a mean updraft inside a cumulus cloud was introduced and the updraft velocity was self-consistently determined in such a way that the mean turbulent velocity within the box vanished. All the degrees of freedom of the cloud droplets and turbulence fields were numerically integrated. The box ascended quickly inside the cumulus cloud due to the updraft and the mean radius of the droplets grew from 10 to 24 μm for about 10 min. The turbulent flow tended to slow down the time evolutions of the updraft velocity, the box altitude and the mean cloud droplet radius. The size distribution of the cloud droplets in the updraft case was narrower than in the absence of the updraft. It was also found that the wavenumeber spectra of the variances of the temperature and water vapor mixing ratio were nearly constant in the low wavenumber range. The future development of the new method was argued.

  3. Cloud-cloud Collision in the Galactic Center 50 km s$^{-1}$ Molecular Cloud

    CERN Document Server

    Tsuboi, Masato; Uehara, Kenta

    2015-01-01

    We performed a search of star-forming sites influenced by external factors, such as SNRs, HII regions, and cloud-cloud collisions, to understand the star-forming activity in the Galactic center region using the NRO Galactic Center Survey in SiO $v=0, J=2-1$, H$^{13}$CO$^+ J=1-0$, and CS $J=1-0$ emission lines obtained by the Nobeyama 45-m telescope. We found a half-shell like feature (HSF) with a high integrated line intensity ratio of $ int T_{ mathrm B}$(SiO $v=0, J=2-1$)$dv$/$ int T_{ mathrm B}$(H$^{13}$CO$^+ J=1-0$)$dv sim6-8$ in the 50 km s$^{-1}$ molecular cloud, which is a most conspicuous molecular cloud in the region and harbors an active star-forming site seen as several compact HII regions. The high ratio in the HSF indicates that the cloud contains huge shocked molecular gas. The HSF is also seen as a half-shell feature in the position-velocity diagram. A hypothesis explaining the chemical and kinetic properties of the HSF is that the feature is originated by a cloud-cloud collision (CCC). We anal...

  4. Study to perform preliminary experiments to evaluate particle generation and characterization techniques for zero-gravity cloud physics experiments

    Science.gov (United States)

    Katz, U.

    1982-01-01

    Methods of particle generation and characterization with regard to their applicability for experiments requiring cloud condensation nuclei (CCN) of specified properties were investigated. Since aerosol characterization is a prerequisite to assessing performance of particle generation equipment, techniques for characterizing aerosol were evaluated. Aerosol generation is discussed, and atomizer and photolytic generators including preparation of hydrosols (used with atomizers) and the evaluation of a flight version of an atomizer are studied.

  5. The design of cloud workflow systems

    CERN Document Server

    Liu, Xiao; Zhang, Gaofeng

    2011-01-01

    Cloud computing is the latest market-oriented computing paradigm which brings software design and development into a new era characterized by ""XaaS"", i.e. everything as a service. Cloud workflows, as typical software applications in the cloud, are composed of a set of partially ordered cloud software services to achieve specific goals. However, due to the low QoS (quality of service) nature of the cloud environment, the design of workflow systems in the cloud becomes a challenging issue for the delivery of high quality cloud workflow applications. To address such an issue, this book presents

  6. Stable atomic hydrogen: Polarized atomic beam source

    International Nuclear Information System (INIS)

    We have carried out experiments with stable atomic hydrogen with a view to possible applications in polarized targets or polarized atomic beam sources. Recent results from the stabilization apparatus are described. The first stable atomic hydrogen beam source based on the microwave extraction method (which is being tested ) is presented. The effect of the stabilized hydrogen gas density on the properties of the source is discussed. (orig.)

  7. Do atoms and anti-atoms obey the same laws of physics?

    CERN Multimedia

    Jeffrey Hangst

    2010-01-01

    ALPHA physicists have recently succeeded in trapping anti-atoms for the first time. Being able to hold on to the simplest atoms of antimatter is an important step towards the collaboration’s ultimate goal: precision spectroscopic comparison of hydrogen and antihydrogen. The question they are seeking to answer: do atoms and anti-atoms obey the same laws of physics? The Standard Model says that they must.   The ALPHA Collaboration celebrates the successful results. The ALPHA collaboration has taken it up a gear and trapped 38 atoms of antihydrogen for the first time. Antihydrogen atoms have been mass-produced at the Antiproton Decelerator (AD) since 2002, when ATHENA (ALPHA’s predecessor) and ATRAP learned how to mix clouds of antiprotons and positrons at cryogenic temperatures. However, these anti-atoms were not confined, and flew off in a few microseconds to meet their fate: annihilation with matter in the walls of the experiment. ALPHA uses antiprotons produced at...

  8. Graph kernels between point clouds

    CERN Document Server

    Bach, Francis

    2007-01-01

    Point clouds are sets of points in two or three dimensions. Most kernel methods for learning on sets of points have not yet dealt with the specific geometrical invariances and practical constraints associated with point clouds in computer vision and graphics. In this paper, we present extensions of graph kernels for point clouds, which allow to use kernel methods for such ob jects as shapes, line drawings, or any three-dimensional point clouds. In order to design rich and numerically efficient kernels with as few free parameters as possible, we use kernels between covariance matrices and their factorizations on graphical models. We derive polynomial time dynamic programming recursions and present applications to recognition of handwritten digits and Chinese characters from few training examples.

  9. BARRIERS TO GOVERNMENT CLOUD ADOPTION

    DEFF Research Database (Denmark)

    Tweneboah-Koduah, Samuel; Tsetse, Anthony; Endicott-Popovsky, Barbara

    2014-01-01

    Besides the benefits are there possible challenges government agencies are likely to encounter should they decide to adopt cloud computing? What strategies should be deployed to overcome the inhibitors of cloud computing? These are but few questions this paper aims to investigate. Studies have...... shown that, cloud computing has become a strategic direction for many government agencies and is already being deployed in many critical areas of the government's cyber infrastructure. The benefits and the challenges of cloud adoption have heightened interest of academic research in recent times. We are...... greater problems from government information management. This study is based on unstructured interviews from selected government agencies in Ghana. The study is grounded on the theory of technology, organization and environment (TOE) framework. Major inhibiting factors identified include lack of basic...

  10. Electron Cloud: an Analytic View

    CERN Document Server

    Vos, L

    1998-01-01

    Electron cloud activity has been observed in some positron storage rings but not in others. It is a major concern for the LHC. In this paper the electron cloud problematics is treated purely analytica lly. The equilibrium electron cloud density is derived from the standard photon production rate, taking into account the photo-electric yield and the process of secondary emission. A fundamental ingre dient in the derivation is the Kollath{2] energy spectrum of the secondary emission. The phenomenon of space charge is discussed as well. The transverse acceleration of the electrons by the bunches is used to introduce the concept of closely and sparsely bunched beams. There is a fundamental difference between them, especially from the point of view of power deposition. Expressions for an equivalen t transverse impedance and imaginary tune shift are derived. Finally the analysis is confronted with electron cloud observations in existing positron machines (DAPHINE, PF, BEPC) before it is applied to the LHC. It comes...

  11. The Hercules-Aquila Cloud

    CERN Document Server

    Belokurov, V; Bell, E F; Irwin, M J; Hewett, P C; Koposov, S; Rockosi, C M; Gilmore, G; Zucker, D B; Fellhauer, M; Wilkinson, M I; Bramich, D M; Vidrih, S; Rix, H W; Beers, T C; Schneider, D P; Barentine, J C; Brewington, H; Brinkmann, J; Harvanek, M; Krzesínski, J; Long, D; Pan, K; Snedden, S A; Malanushenko, O; Malanushenko, V

    2007-01-01

    We present evidence for a substantial overdensity of stars in the direction of the constellations of Hercules and Aquila. The Cloud is centered at a Galactic longitude of about 40 degrees and extends above and below the Galactic plane by at least 50 degrees. Given its off-centeredness and height, it is unlikely that the Hercules-Aquila Cloud is related to the bulge or thick disk. More likely, this is a new structural component of the Galaxy that passes through the disk. The Cloud stretches about 80 degrees in longitude. Its heliocentric distance lies between 10 and 20 kpc so that the extent of the Cloud in projection is roughly 20 kpc by 15 kpc. It has an absolute magnitude of -13 and its stellar population appears to be comparable to, but somewhat more metal-rich than, M92.

  12. Research computing in a distributed cloud environment

    International Nuclear Information System (INIS)

    The recent increase in availability of Infrastructure-as-a-Service (IaaS) computing clouds provides a new way for researchers to run complex scientific applications. However, using cloud resources for a large number of research jobs requires significant effort and expertise. Furthermore, running jobs on many different clouds presents even more difficulty. In order to make it easy for researchers to deploy scientific applications across many cloud resources, we have developed a virtual machine resource manager (Cloud Scheduler) for distributed compute clouds. In response to a user's job submission to a batch system, the Cloud Scheduler manages the distribution and deployment of user-customized virtual machines across multiple clouds. We describe the motivation for and implementation of a distributed cloud using the Cloud Scheduler that is spread across both commercial and dedicated private sites, and present some early results of scientific data analysis using the system.

  13. Research computing in a distributed cloud environment

    Science.gov (United States)

    Fransham, K.; Agarwal, A.; Armstrong, P.; Bishop, A.; Charbonneau, A.; Desmarais, R.; Hill, N.; Gable, I.; Gaudet, S.; Goliath, S.; Impey, R.; Leavett-Brown, C.; Ouellete, J.; Paterson, M.; Pritchet, C.; Penfold-Brown, D.; Podaima, W.; Schade, D.; Sobie, R. J.

    2010-11-01

    The recent increase in availability of Infrastructure-as-a-Service (IaaS) computing clouds provides a new way for researchers to run complex scientific applications. However, using cloud resources for a large number of research jobs requires significant effort and expertise. Furthermore, running jobs on many different clouds presents even more difficulty. In order to make it easy for researchers to deploy scientific applications across many cloud resources, we have developed a virtual machine resource manager (Cloud Scheduler) for distributed compute clouds. In response to a user's job submission to a batch system, the Cloud Scheduler manages the distribution and deployment of user-customized virtual machines across multiple clouds. We describe the motivation for and implementation of a distributed cloud using the Cloud Scheduler that is spread across both commercial and dedicated private sites, and present some early results of scientific data analysis using the system.

  14. Neutral atom traps.

    Energy Technology Data Exchange (ETDEWEB)

    Pack, Michael Vern

    2008-12-01

    This report describes progress in designing a neutral atom trap capable of trapping sub millikelvin atom in a magnetic trap and shuttling the atoms across the atom chip from a collection area to an optical cavity. The numerical simulation and atom chip design are discussed. Also, discussed are preliminary calculations of quantum noise sources in Kerr nonlinear optics measurements based on electromagnetically induced transparency. These types of measurements may be important for quantum nondemolition measurements at the few photon limit.

  15. MULTIPHOTON IONIZATION OF ATOMS

    OpenAIRE

    Mainfray, G.

    1985-01-01

    Multiphoton ionization of one-electron atoms, such as atomic hydrogen and alkaline atoms, is well understood and correctly described by rigorous theoretical models. The present paper will be devoted to collisionless multiphoton ionization of many-electron atoms as rare gases. It induces removal of several electrons and the production of multiply charged ions. Up to Xe5+ ions are produced in Xe atoms. Doubly charged ions can be produced, either by simultaneous excitation of two electrons, or b...

  16. Data mining in Cloud Computing

    OpenAIRE

    Ruxandra-Ştefania PETRE

    2012-01-01

    This paper describes how data mining is used in cloud computing. Data Mining is used for extracting potentially useful information from raw data. The integration of data mining techniques into normal day-to-day activities has become common place. Every day people are confronted with targeted advertising, and data mining techniques help businesses to become more efficient by reducing costs. Data mining techniques and applications are very much needed in the cloud computing paradigm. The implem...

  17. Notes on Cloud computing principles

    OpenAIRE

    Sandholm, Thomas; Lee, Dongman

    2015-01-01

    This letter provides a review of fundamental distributed systems and economic Cloud computing principles. These principles are frequently deployed in their respective fields, but their inter-dependencies are often neglected. Given that Cloud Computing first and foremost is a new business model, a new model to sell computational resources, the understanding of these concepts is facilitated by treating them in unison. Here, we review some of the most important concepts and how they relate to ea...

  18. Towards Successful Cloud Ordering Service

    OpenAIRE

    Chen Yan-Kwang; Chen Yi-Ju; Chiu Fei-Rung; Wang Cheng-Yi

    2015-01-01

    Background: The rise of cloud services has led to a drastic growth of e-commerce and a greater investment in development of new cloud services systems by related industries. For SaaS developers, it is important to understand customer needs and make use of available resources at as early as the system design and development stage. Objectives: This study integrates E-commerce Systems (ECS) Success model and Importance-Performance Analysis (IPA) into empirical research of the critical factors fo...

  19. Cloud Database Management System (CDBMS)

    OpenAIRE

    Snehal B. Shende; Prajakta P. Chapke

    2015-01-01

    Cloud database management system is a distributed database that delivers computing as a service. It is sharing of web infrastructure for resources, software and information over a network. The cloud is used as a storage location and database can be accessed and computed from anywhere. The large number of web application makes the use of distributed storage solution in order to scale up. It enables user to outsource the resource and services to the third party server. This paper include, the r...

  20. Architectural Operations in Cloud Computing

    OpenAIRE

    Ragnar Skúlason 1982

    2011-01-01

    Rapid scalability is important in cloud computing in order to serve growing communities and optimize hardware costs. This scalability can be hard to achieve, especially in software with static architecture. Changing software architecture of running systems on multiple devices over the Internet is a hard and delicate process as updating live software can cause faults and failures while software systems are being restarted. Taking the study of software architecture to the dynamics of the cloud ...

  1. L1599B: Cloud Envelope and C+ Emission in a Region of Moderately Enhanced Radiation Field

    CERN Document Server

    Goldsmith, Paul F; Langer, William D; Liu, Tie; Requena-Torres, Miguel; Ricken, Oliver; Riquelme, Denise

    2016-01-01

    We study the effects of an asymmetric radiation field on the properties of a molecular cloud envelope. We employ observations of carbon monoxide (12CO and 13CO), atomic carbon, ionized carbon, and atomic hydrogen to analyze the chemical and physical properties of the core and envelope of L1599B, a molecular cloud forming a portion of the ring at approximately 27 pc from the star Lambda Ori. The O III star provides an asymmetric radiation field that produces a moderate enhancement of the external radiation field. Observations of the [CII] fine structure line with the GREAT instrument on SOFIA indicate a significant enhanced emission on the side of the cloud facing the star, while the [Ci], 12CO and 13CO J = 1-0 and 2-1, and 12CO J = 3-2 data from the PMO and APEX telescopes suggest a relatively typical cloud interior. The atomic, ionic, and molecular line centroid velocities track each other very closely, and indicate that the cloud may be undergoing differential radial motion. The HI data from the Arecibo GAL...

  2. ÉTUDE DES PROPRIÉTÉS DE PROPAGATION
    D'UN LASER À ATOMES

    OpenAIRE

    Riou, Jean-Félix

    2006-01-01

    This manuscript presents various experimental and theoretical aspects concerning a specificsystem of atom optics : the atom laser. In our experiment, this one results from aBose-Einstein condensate of rubidium 87 and we thus initially detail the various coolingtechniques used to obtain this coherent atomic source in a hybrid ferromagnetic trap.The atom lasers we produce are extracted from the condensed cloud by radiofrequency,and propagate vertically under the effect of gravity. One specifici...

  3. Survey: Risk Assessment for Cloud Computing

    OpenAIRE

    Drissi S.; Houmani H.; Medromi H.

    2013-01-01

    with the increase in the growth of cloud computing and the changes in technology that have resulted a new ways for cloud providers to deliver their services to cloud consumers, the cloud consumers should be aware of the risks and vulnerabilities present in the current cloud computing environment. An information security risk assessment is designed specifically for that task. However, there is lack of structured risk assessment approach to do it. This paper aims to survey existing knowledge re...

  4. Representation of cloud ecosystem using engineering methodologies

    OpenAIRE

    Manu AR; Dr. Vinod Kumar Agrawal; Dr. K N Bala Subramanya Murthy

    2013-01-01

    Cloud Computing has fascinated massive consideration for business in spite of lot of technologies and business models in the market. The operational particulars within the cloud are not coherent enough to customers. Hence, this paper provides the method to derive trusted cloud computing scaffold. This scaffold is represented using the engineering methodologies. In this work we use elementary engineering principles of computation to represent the cloud eco-system, comprising of complete cloud ...

  5. Secure Data Service Outsourcing with Untrusted Cloud

    OpenAIRE

    Xiong, Huijun

    2013-01-01

    Outsourcing data services to the cloud is a nature fit for cloud usage. However, increasing security and privacy concerns from both enterprises and individuals on their outsourced data inhibit this trend. In this dissertation, we introduce service-centric solutions to address two types of security threats existing in the current cloud environments: semi-honest cloud providers and malicious cloud customers. Our solution aims not only to provide confidentiality and access controllability of out...

  6. CLOUD COMPUTING: A technology for Communication

    OpenAIRE

    Priya Trivedi; , Stuti Garg

    2013-01-01

    This paper illustrate about cloud computing. Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over a networks (typically the Internet). The name comes from the use of a cloud-shaped symbol as an abstraction for the complex infrastructure it contains in system diagrams. Cloud computing entrusts remote services with a user's data, software and computation. Cloud computing relies on sharing of resources to achieve coherence and economies o...

  7. The CloudMdsQL Multistore System

    OpenAIRE

    Kolev, Boyan; Bondiombouy, Carlyna; Valduriez, Patrick; Jiménez-Peris, Ricardo; Pau, Raquel; Pereira, José

    2016-01-01

    The blooming of different cloud data management infrastructures has turned multistore systems to a major topic in the nowadays cloud landscape. In this demonstration, we present a Cloud Multidatastore Query Language (CloudMdsQL), and its query engine. CloudMdsQL is a functional SQL-like language, capable of querying multiple heterogeneous data stores (relational and NoSQL) within a single query that may contain embedded invocations to each data store's native query interface. The major innova...

  8. Brewing Analytics Quality for Cloud Performance

    OpenAIRE

    Chen, Li; Jain, Pooja; Chow, Kingsum; Guirguis, Emad; Wu, Tony

    2015-01-01

    Cloud computing has become increasingly popular. Many options of cloud deployments are available. Testing cloud performance would enable us to choose a cloud deployment based on the requirements. In this paper, we present an innovative process, implemented in software, to allow us to assess the quality of the cloud performance data. The process combines performance data from multiple machines, spanning across user experience data, workload performance metrics, and readily available system per...

  9. A Comprehensive Survey on Cloud Computing

    OpenAIRE

    Md. Imran Alam; Manjusha Pandey; Siddharth S Rautaray

    2015-01-01

    Cloud Computing is an innovation ideas that helps in reducing the computing cost. Cloud Computing offers better computing through improved utilization and reduced administration and infrastructure costs. Cloud computing is the long-held dream of computing as a utility. Cloud Computing is the combination of Software as a Service (SaaS) and Utility Computing. Cloud computing shares characteristics with autonomic computing, peer to peer, grid computing, client server model, mainframe computer an...

  10. Clouds of high contrast on Uranus.

    Science.gov (United States)

    Karkoschka, E

    1998-04-24

    Near-infrared images of Uranus taken with the Hubble Space Telescope in July and October 1997 revealed discrete clouds with contrasts exceeding 10 times the highest contrast observed before with other techniques. At visible wavelengths, these 10 clouds had lower contrasts than clouds seen by Voyager 2 in 1986. Uranus' rotational rates for southern latitudes were identical in 1986 and 1997. Clouds in northern latitudes rotate slightly more slowly than clouds in opposite southern latitudes. PMID:9554844

  11. Cloud computing methods and practical approaches

    CERN Document Server

    Mahmood, Zaigham

    2013-01-01

    This book presents both state-of-the-art research developments and practical guidance on approaches, technologies and frameworks for the emerging cloud paradigm. Topics and features: presents the state of the art in cloud technologies, infrastructures, and service delivery and deployment models; discusses relevant theoretical frameworks, practical approaches and suggested methodologies; offers guidance and best practices for the development of cloud-based services and infrastructures, and examines management aspects of cloud computing; reviews consumer perspectives on mobile cloud computing an

  12. Entrainment and mixing mechanism in monsoon clouds

    Science.gov (United States)

    Bera, Sudarsan; Prabhakaran, Thara; Pandithurai, Govindan; Brenguier, Jean-Louis

    2015-04-01

    Entrainment and consequent mixing impacts the cloud microphysical parameters and droplet size distribution (DSD) significantly which are very important for cloud radiative properties and the mechanism for first rain drop formation. The entrainment and mixing mechanisms are investigated in this study using in situ observations in warm cumulus clouds over monsoon region. Entrainment is discussed in the framework of the homogeneous and inhomogeneous mixing concepts and their effects on cloud droplet size distribution, number concentration, liquid water content and mean radius are described. The degree of homogeneity increases with droplet number concentration and adiabatic fraction, indicating homogeneous type mixing in the cloud core where dilution is less. Inhomogeneous mixing is found to be a dominating process at cloud edges where dilution is significant. Cloud droplet size distribution (DSD) is found to shift towards lower sizes during a homogeneous mixing event in the cloud core whereas spectral width of DSD decreases due to inhomogeneous mixing at cloud edges. Droplet size spectra suggests that largest droplets are mainly formed in the less diluted cloud core while diluted cloud edges have relatively smaller droplets, so that raindrop formation occurs mainly in the core of the cloud. The origin of the entrained parcels in deep cumulus clouds is investigated using conservative thermodynamical parameters. The entrained parcels originate from a level close to the observation level or slightly below through lateral edges. Cloud edges are significantly diluted due to entrainment of sub-saturated environmental air which can penetrate several hundred meters inside the cloud before it gets mixed completely with the cloud mass. Less diluted parcels inside the cloud core originates from a level much below the cloud base height. Penetrating downdraft from cloud top is seldom observed at the observation level and strong downdrafts may be attributed to in-cloud oscillation

  13. Syncing Mobile Applications with Cloud Storage Services

    OpenAIRE

    Paul POCATILU; Catalin BOJA; Cristian CIUREA

    2013-01-01

    Cloud data storage is an option available almost on any mobile platform. Nowadays, there are multiple solutions for syncing data in mobile applications. The aim of the paper is to analyze mobile application developers’ possibilities for syncing content using major free cloud storage providers. The paper describes the cloud computing in mobile context and highlights cloud providers APIs. Experimental results are analyzed in order to identify the best cloud storage solution for syncing mobile...

  14. VMware vCloud director cookbook

    CERN Document Server

    Langenhan, Daniel

    2013-01-01

    VMware vCloud Director Cookbook will adopt a Cookbook-based approach. Packed with illustrations and programming examples, this book explains the simple as well as the complex recipes in an easy-to-understand language.""VMware vCloud Director Cookbook"" is aimed at system administrators and technical architects moving from a virtualized environment to cloud environments. Familiarity with cloud computing platforms and some knowledge of virtualization and managing cloud environments is expected.

  15. Cloud Computing with Related Enabling Technologies

    OpenAIRE

    Abah Joshua; Francisca Ogwueleka

    2012-01-01

    Cloud Computing is a concept that has been defined differently by many and there seem not to be a consensus. Despite these views, cloud computing is not a complete new idea as it has intricate connections to technologies or domain such as the Grid Computing paradigm, and the general distributed computing. This overview gives the basic concept of cloud computing, and highlights the relationship between Cloud computing and other cloud enabling technologies by providing their similarities and di...

  16. Cloud Infrastructure Service Management - A Review

    OpenAIRE

    2012-01-01

    The new era of computing called Cloud Computing allows the user to access the cloud services dynamically over the Internet wherever and whenever needed. Cloud consists of data and resources; and the cloud services include the delivery of software, infrastructure, applications, and storage over the Internet based on user demand through Internet. In short, cloud computing is a business and economic model allowing the users to utilize high-end computing and storage virtually with minimal infrast...

  17. Titanium atom detection by resonance fluorescence excited with a nitrogen laser

    International Nuclear Information System (INIS)

    Coincidence of wave lengths of nitrogen laser basing lines and resonance transitions in titanium atom is investigated. It is shown that resonance fluorescence excited by nitrogen laser can be used for absolute titanium atom density measurements. Experiments on titanium atom detection in a vapour cloud formed under irradiation of a titanium target in vacuum by dye laser pulse, are conducted. Fluorescence extinguishing is observed under high evaporation power

  18. Design and fabrication of diffractive atom chips for laser cooling and trapping

    CERN Document Server

    Cotter, J P; Griffin, P F; Rabey, I M; Docherty, K; Riis, E; Arnold, A S; Hinds, E A

    2016-01-01

    It has recently been shown that optical reflection gratings fabricated directly into an atom chip provide a simple and effective way to trap and cool substantial clouds of atoms [1,2]. In this article we describe how the gratings are designed and micro-fabricated and we characterise their optical properties, which determine their effectiveness as a cold atom source. We use simple scalar diffraction theory to understand how the morphology of the gratings determines the power in the diffracted beams.

  19. Cloud computing for comparative genomics

    Directory of Open Access Journals (Sweden)

    Pivovarov Rimma

    2010-05-01

    Full Text Available Abstract Background Large comparative genomics studies and tools are becoming increasingly more compute-expensive as the number of available genome sequences continues to rise. The capacity and cost of local computing infrastructures are likely to become prohibitive with the increase, especially as the breadth of questions continues to rise. Alternative computing architectures, in particular cloud computing environments, may help alleviate this increasing pressure and enable fast, large-scale, and cost-effective comparative genomics strategies going forward. To test this, we redesigned a typical comparative genomics algorithm, the reciprocal smallest distance algorithm (RSD, to run within Amazon's Elastic Computing Cloud (EC2. We then employed the RSD-cloud for ortholog calculations across a wide selection of fully sequenced genomes. Results We ran more than 300,000 RSD-cloud processes within the EC2. These jobs were farmed simultaneously to 100 high capacity compute nodes using the Amazon Web Service Elastic Map Reduce and included a wide mix of large and small genomes. The total computation time took just under 70 hours and cost a total of $6,302 USD. Conclusions The effort to transform existing comparative genomics algorithms from local compute infrastructures is not trivial. However, the speed and flexibility of cloud computing environments provides a substantial boost with manageable cost. The procedure designed to transform the RSD algorithm into a cloud-ready application is readily adaptable to similar comparative genomics problems.

  20. Liquid Cloud Responses to Soot

    Science.gov (United States)

    Koch, D. M.

    2010-12-01

    Although soot absorption warms the atmosphere, soot may cause climate cooling due to its effects on liquid clouds, including contribution to cloud condensation nuclei (CCN) and semi-direct effects. Six global models that include aerosol microphysical schemes conducted three soot experiments. The average model cloud radiative response to biofuel soot (black and organic carbon), including both indirect and semi-direct effects, is -0.12 Wm-2, comparable in size but opposite in sign to the respective direct atmospheric warming. In a more idealized fossil fuel black carbon only experiment, some models calculated a positive cloud response because the soot provided a deposition sink for sulfate, decreasing formation of more viable CCN. Biofuel soot particles were typically assumed to be larger and more hygroscopic than for fossil fuel soot and therefore caused more negative forcing, as also found in previous studies. Diesel soot (black and organic carbon) experiments had relatively smaller cloud impacts with five of the models competition of opposing effects on the CCN population make it difficult to extrapolate from idealized experiments to likely impacts of realistic potential emission changes. However, results so far suggest that soot-induced cloud-cooling effects are comparable in magnitude to the direct warming effects from soot absorption.

  1. Horizontally oriented plates in clouds

    CERN Document Server

    Bréon, François-Marie

    2011-01-01

    Horizontally oriented plates in clouds generate a sharp specular reflectance signal in the glint direction, often referred to as "subsun". This signal (amplitude and width) may be used to analyze the relative area fraction of oriented plates in the cloud top layer and their characteristic tilt angle to the horizontal. We make use of spaceborne measurements from the POLDER instrument to provide a statistical analysis of these parameters. More than half of the clouds show a detectable maximum reflectance in the glint direction, although this maximum may be rather faint. The typical effective fraction (area weighted) of oriented plates in clouds lies between 10-3 and 10-2. For those oriented plates, the characteristic tilt angle is less than 1 degree in most cases. These low fractions imply that the impact of oriented plates on the cloud albedo is insignificant. The largest proportion of clouds with horizontally oriented plates is found in the range 500-700 hPa, in agreement with typical in situ observation of p...

  2. CHPS IN CLOUD COMPUTING ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    K.L.Giridas

    2012-10-01

    Full Text Available Workflow have been utilized to characterize a various form of applications concerning high processing and storage space demands. So, to make the cloud computing environment more eco-friendly,our research project was aiming in reducing E-waste accumulated by computers. In a hybrid cloud, the user has flexibility offered by public cloud resources that can be combined to the private resources pool as required. Our previous work described the process of combining the low range and mid range processors with the high end processor to make the IT environment without e-waste. Then we focused on the allocation of resources in an optimal manner with respect to bandwidth and processors’ ability. In this paper we deal with presenting (CHPS Compatibility of Hybrid processor scheduler in green IT cloud computing environment. CHPS decides which resources should be chartered from the public cloud and combined to the private cloud to offer adequate processing power to perform a workflow inside a specified execution time. We present widespread experimental and simulation results which illustrate that CHPS can decrease costs as attaining the recognized preferred execution time.

  3. Cavity-aided magnetic-resonance microscopy of atoms in optical lattices

    CERN Document Server

    Purdy, Tom P; Brooks, Daniel W C; Botter, Thierry; Stamper-Kurn, Dan M

    2010-01-01

    Magnetic resonance imaging (MRI) is a powerful technique for investigating the microscopic properties and dynamics of physical systems. In this work we demonstrate state-sensitive MRI of ultracold atoms in an optical lattice. Single-shot spatial resolution is 120 nm, well below the lattice spacing, and number sensitivity is +/-2.4 for 150 atoms on a single site, well below Poissonian atom-number fluctuations. We achieve this by combining high-spatial-resolution control over the atomic spin using an atom chip, together with nearly quantum-limited spin measurement, obtained by dispersively coupling the atoms to light in a high-finesse optical cavity. The MRI is minimally disruptive of the atoms' internal state, preserving the magnetisation of the gas for subsequent experiments. Using this technique, we observe the nonequilibrium transport dynamics of the atoms among individual lattice sites. We see the atom cloud initially expand ballistically, followed by the onset of interaction-inhibited transport.

  4. Time-of-flight detection of ultra-cold atoms using resonant frequency modulation imaging.

    Science.gov (United States)

    Hardman, K S; Wigley, P B; Everitt, P J; Manju, P; Kuhn, C C N; Robins, N P

    2016-06-01

    Resonant frequency modulation imaging is used to detect free falling ultra-cold atoms. A theoretical comparison of fluorescence imaging (FI) and frequency modulation imaging (FMI) is made, indicating that for low optical depth clouds, FMI accomplished a higher signal-to-noise ratio under conditions necessary for a 200 μm spatially resolved atom interferometer. A 750 ms time-of-flight measurement reveals near atom shot-noise limited number measurements of 2×106 Bose-condensed Rb87 atoms. The detection system is applied to high precision spinor BEC based atom interferometer. PMID:27244400

  5. Atomic and molecular manipulation

    CERN Document Server

    Mayne, Andrew J

    2011-01-01

    Work with individual atoms and molecules aims to demonstrate that miniaturized electronic, optical, magnetic, and mechanical devices can operate ultimately even at the level of a single atom or molecule. As such, atomic and molecular manipulation has played an emblematic role in the development of the field of nanoscience. New methods based on the use of the scanning tunnelling microscope (STM) have been developed to characterize and manipulate all the degrees of freedom of individual atoms and molecules with an unprecedented precision. In the meantime, new concepts have emerged to design molecules and substrates having specific optical, mechanical and electronic functions, thus opening the way to the fabrication of real nano-machines. Manipulation of individual atoms and molecules has also opened up completely new areas of research and knowledge, raising fundamental questions of "Optics at the atomic scale", "Mechanics at the atomic scale", Electronics at the atomic scale", "Quantum physics at the atomic sca...

  6. Advances in atomic spectroscopy

    CERN Document Server

    Sneddon, J

    2000-01-01

    This fifth volume of the successful series Advances in Atomic Spectroscopy continues to discuss and investigate the area of atomic spectroscopy.It begins with a description of the use of various atomic spectroscopic methods and applications of speciation studies in atomic spectroscopy. The emphasis is on combining atomic spectroscopy with gas and liquid chromatography. In chapter two the authors describe new developments in tunable lasers and the impact they will have on atomic spectroscopy. The traditional methods of detection, such as photography and the photomultiplier, and how they are being replaced by new detectors is discussed in chapter three. The very active area of glow discharge atomic spectrometry is presented in chapter four where, after a brief introduction and historical review, the use of glow discharge lamps for atomic spectroscopy and mass spectrometry are discussed. Included in this discussion is geometry and radiofrequency power. The future of this source in atomic spectroscopy is also dis...

  7. MAGIA - using atom interferometry to determine the Newtonian gravitational constant

    International Nuclear Information System (INIS)

    We describe our experiment MAGIA (misura accurata di G mediante interferometria atomica), in which we will use atom interferometry to perform a high precision measurement of the Newtonian gravitational constant G. Free-falling laser-cooled atoms in a vertical atomic fountain will be accelerated due to the gravitational potential of nearby source masses (SMs). Detecting this acceleration with techniques of Raman atom interferometry will enable us to assign a value to G. To suppress systematic effects we will implement a double-differential measurement. This includes launching two atom clouds in a gradiometer configuration and moving the SMs to different vertical positions. We briefly summarize the general idea of the MAGIA experiment and put it in the context of other high precision G-measurements. We present the current status of the experiment and report on analyses of the expected measurement accuracy

  8. Storing Quantum Information via Atomic Dark Resonances

    CERN Document Server

    Caruso, Filippo

    2010-01-01

    In this thesis, after a brief review of some concepts of Quantum Optics, we analyze a three-level atomic system in the conditions of electromagnetically induced transparency (EIT), and we investigate the propagation of a gaussian pulse along a cigar-shaped cloud of both cold and hot atoms in EIT regime. In particular, we show that it is possible to amplify a slow propagating pulse without population inversion. We also analyze the regime of anomalous light propagation showing that it is possible to observe superluminal energy propagation. In these conditions, it is possible to imprint reversibly ('write') the information carried by the photons onto the atoms, specifically as a coherent pattern of atomic spins, and later the information stored in the atomic spins can be transferred back ('read') to the light field, implementing in this way a quantum memory. Besides, we analyze the propagation of a quantum field in an EIT medium sustaining dark state polaritons (DSP) in a quasi-particle picture. Here, the decohe...

  9. Towards a random laser with cold atoms

    CERN Document Server

    Guerin, William; Michaud, Franck; Brivio, Davide; Froufe-Pérez, Luis S; Carminati, Rémi; Eremeev, Vitalie; Goetschy, Arthur; Skipetrov, Sergey S; Kaiser, Robin

    2009-01-01

    Atoms can scatter light and they can also amplify it by stimulated emission. From this simple starting point, we examine the possibility of realizing a random laser in a cloud of laser-cooled atoms. The answer is not obvious as both processes (elastic scattering and stimulated emission) seem to exclude one another: pumping atoms to make them behave as amplifier reduces drastically their scattering cross-section. However, we show that even the simplest atom model allows the efficient combination of gain and scattering. Moreover, supplementary degrees of freedom that atoms offer allow the use of several gain mechanisms, depending on the pumping scheme. We thus first study these different gain mechanisms and show experimentally that they can induce (standard) lasing. We then present how the constraint of combining scattering and gain can be quantified, which leads to an evaluation of the random laser threshold. The results are promising and we draw some prospects for a practical realization of a random laser wit...

  10. Clouds Composition in Super-Earth Atmospheres: Chemical Equilibrium Calculations

    Science.gov (United States)

    Kempton, Eliza M.-R.; Mbarek, Rostom

    2015-12-01

    Attempts to determine the composition of super-Earth atmospheres have so far been plagued by the presence of clouds. Yet the theoretical framework to understand these clouds is still in its infancy. For the super-Earth archetype GJ 1214b, KCl, Na2S, and ZnS have been proposed as condensates that would form under the condition of chemical equilibrium, if the planet’s atmosphere has a bulk composition near solar. Condensation chemistry calculations have not been presented for a wider range of atmospheric bulk composition that is to be expected for super-Earth exoplanets. Here we provide a theoretical context for the formation of super-Earth clouds in atmospheres of varied composition by determining which condensates are likely to form, under the assumption of chemical equilibrium. We model super-Earth atmospheres assuming they are formed by degassing of volatiles from a solid planetary core of chondritic material. Given the atomic makeup of these atmospheres, we minimize the global Gibbs free energy of over 550 gases and condensates to obtain the molecular composition of the atmospheres over a temperature range of 350-3,000 K. Clouds should form along the temperature-pressure boundaries where the condensed species appear in our calculations. The super-Earth atmospheres that we study range from highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are both sub-solar and super-solar, thereby spanning a diverse range of atmospheric composition that is appropriate for low-mass exoplanets. Some condensates appear across all of our models. However, the majority of condensed species appear only over specific ranges of H:O and C:O ratios. We find that for GJ 1214b, KCl is the primary cloud-forming condensate at solar composition, in agreement with previous work. However, for oxidizing atmospheres, where H:O is less than unity, K2SO4 clouds form instead. For carbon-rich atmospheres with super-solar C:O ratios, graphite clouds additionally appear. At

  11. Sensitive Detection of Individual Neutral Atoms in a Strong Coupling Cavity QED System

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng-Fei; ZHANG Yu-Chi; LI Gang; DU Jin-Jin; ZHANG Yan-Feng; GUO Yan-Qiang; WANG Jun-Min; ZHANG Tian-Cai; LI Wei-Dong

    2011-01-01

    We experimentally demonstrate real-time detection of individual cesium atoms by using a high-finesse optical micro-cavity in a strong coupling regime.A cloud of cesium atoms is trapped in a magneto-optical trap positioned at 5 mm above the micro-cavity center.The atoms fall down freely in gravitation after shutting off the magnetooptical trap and pass through the cavity.The cavity transmission is strongly affected by the atoms in the cavity, which enables the micro-cavity to sense the atoms individually.We detect the single atom transits either in the resonance or various detunings.The single atom vacuum-Rabi splitting is directly measured to be Ω = 2π × 23.9 MHz.The average duration of atom-cavity coupling of about 110μs is obtained according to the probability distribution of the atom transits.%@@ We experimentally demonstrate real-time detection of individual cesium atoms by using a high-finesse optical micro-cavity in a strong coupling regime.A cloud of cesium atoms is trapped in a magneto-optical trap positioned at 5mm above the micro-cavity center.The atoms fall down freely in gravitation after shutting off the magnetooptical trap and pass through the cavity.The cavity transmission is strongly affected by the atoms in the cavity, which enables the micro-cavity to sense the atoms individually.We detect the single atom transits either in the resonance or various detunings.The single atom vacuum-Rabi splitting is directly measured to be Ω=2π×23.9 MHz.The average duration of atom-cavity coupling of about 110μs is obtained according to the probability distribution of the atom transits.

  12. The Community Cloud Atlas - Building an Informed Cloud Watching Community

    Science.gov (United States)

    Guy, N.; Rowe, A.

    2014-12-01

    The sky is dynamic, from long lasting cloud systems to ethereal, fleeting formations. After years of observing the sky and growing our personal collections of cloud photos, we decided to take to social media to share pictures, as well as build and educate a community of cloud enthusiasts. We began a Facebook page, the Community Cloud Atlas, described as "...the place to show off your pictures of the sky, identify clouds, and to discuss how specific cloud types form and what they can tell you about current and future weather." Our main goal has been to encourage others to share their pictures, while we describe the scenes from a meteorological perspective and reach out to the general public to facilitate a deeper understanding of the sky. Nearly 16 months later, we have over 1400 "likes," spanning 45 countries with ages ranging from 13 to over 65. We have a consistent stream of submissions; so many that we decided to start a corresponding blog to better organize the photos, provide more detailed explanations, and reach a bigger audience. Feedback from users has been positive in support of not only sharing cloud pictures, but also to "learn the science as well as admiring" the clouds. As one community member stated, "This is not 'just' a place to share some lovely pictures." We have attempted to blend our social media presence with providing an educational resource, and we are encouraged by the response we have received. Our Atlas has been informally implemented into classrooms, ranging from a 6th grade science class to Meteorology courses at universities. NOVA's recent Cloud Lab also made use of our Atlas as a supply of categorized pictures. Our ongoing goal is to not only continue to increase understanding and appreciation of the sky among the public, but to provide an increasingly useful tool for educators. We continue to explore different social media options to interact with the public and provide easier content submission, as well as software options for

  13. THE ORNL ATOM PROBE

    OpenAIRE

    Miller, M

    1986-01-01

    The ORNL Atom Probe is a microanalytical tool for studies in materials science. The instrument is a combination of a customized version of the vacuum system of the VG FIM-100 atom probe, an ORNL-designed microcomputer-controlled digital timing system, and a double curved CEMA Imaging Atom Probe detector. The atom probe combines four instruments into one - namely a field ion microscope, an energy compensated time-of-flight mass spectrometer, an imaging atom probe, and a pulsed laser atom probe.

  14. Interactions of charged dust particles in clouds of charges

    Science.gov (United States)

    Gundienkov, Vladimir; Yakovlenko, Sergey

    2004-03-01

    Two charged dust particles inside a cloud of charges are considered as Debye atoms forming a Debye molecule. Cassini coordinates are used for the numerical solution of the Poisson-Boltzmann equation for the charged cloud. The electric force acting on a dust particle by the other dust particle was determined by integrating the electrostatic pressure on the surface of the dust particle. It is shown that attractive forces appear when the following two conditions are satisfied. First, the average distance between dust particles should be approximately equal to two Debye radii. Second, attraction takes place when similar charges are concentrated predominantly on the dust particles. If the particles carry a small fraction of total charge of the same polarity, repulsion between the particles takes place at all distances. We apply our results to the experiments with thermoemission plasma and to the experiments with nuclear-pumped plasma.

  15. Clouds and Hazes in Exoplanet Atmospheres

    CERN Document Server

    Marley, Mark S; Cuzzi, Jeffrey N; Kitzmann, Daniel

    2013-01-01

    Clouds and hazes are commonplace in the atmospheres of solar system planets and are likely ubiquitous in the atmospheres of extrasolar planets as well. Clouds affect every aspect of a planetary atmosphere, from the transport of radiation, to atmospheric chemistry, to dynamics and they influence - if not control - aspects such as surface temperature and habitability. In this review we aim to provide an introduction to the role and properties of clouds in exoplanetary atmospheres. We consider the role clouds play in influencing the spectra of planets as well as their habitability and detectability. We briefly summarize how clouds are treated in terrestrial climate models and consider the far simpler approaches that have been taken so far to model exoplanet clouds, the evidence for which we also review. Since clouds play a major role in the atmospheres of certain classes of brown dwarfs we briefly discuss brown dwarf cloud modeling as well. We also review how the scattering and extinction efficiencies of cloud p...

  16. The Evolution of Cloud Computing in ATLAS

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00224309; The ATLAS collaboration; Berghaus, Frank; Love, Peter; Leblanc, Matthew Edgar; Di Girolamo, Alessandro; Paterson, Michael; Gable, Ian; Sobie, Randall; Field, Laurence

    2015-01-01

    The ATLAS experiment has successfully incorporated cloud computing technology and cloud resources into its primarily grid-based model of distributed computing. Cloud R&D activities continue to mature and transition into stable production systems, while ongoing evolutionary changes are still needed to adapt and refine the approaches used, in response to changes in prevailing cloud technology. In addition, completely new developments are needed to handle emerging requirements. This work will describe the overall evolution of cloud computing in ATLAS. The current status of the VM management systems used for harnessing IAAS resources will be discussed. Monitoring and accounting systems tailored for clouds are needed to complete the integration of cloud resources within ATLAS' distributed computing framework. We are developing and deploying new solutions to address the challenge of operation in a geographically distributed multi-cloud scenario, including a system for managing VM images across multiple clouds, ...

  17. The chemistry of interstellar argonium and other probes of the molecular fraction in diffuse clouds

    CERN Document Server

    Neufeld, David A

    2016-01-01

    We present a general parameter study, in which the abundance of interstellar argonium (ArH$^+$) is predicted using a model for the physics and chemistry of diffuse interstellar gas clouds. Results have been obtained as a function of UV radiation field, cosmic-ray ionization rate, and cloud extinction. No single set of cloud parameters provides an acceptable fit to the typical ArH$^+$, OH$^+$ and $\\rm H_2O^+$ abundances observed in diffuse clouds within the Galactic disk. Instead, the observed abundances suggest that ArH$^+$ resides primarily in a separate population of small clouds of total visual extinction of at most 0.02 mag per cloud, within which the column-averaged molecular fraction is in the range $10^{-5} - 10^{-2}$, while OH$^+$ and $\\rm H_2O^+$ reside primarily in somewhat larger clouds with a column-averaged molecular fraction $\\sim 0.2$. This analysis confirms our previous suggestion that the argonium molecular ion is a unique tracer of almost purely atomic gas.

  18. Active probing of cloud thickness and optical depth using wide-angle imaging LIDAR

    International Nuclear Information System (INIS)

    At most optical wavelengths, laser light in a cloud lidar experiment is not absorbed but merely scattered out of the beam, eventually escaping the cloud via multiple scattering. There is much information available in this light scattered far from the input beam, information ignored by traditional 'on-beam' lidar. Monitoring these off-beam returns in a fully space- and time-resolved manner is the essence of our unique instrument, Wide Angle Imaging Lidar (WAIL). In effect, WAIL produces wide-field (60o full-angle) 'movies' of the scattering process and records the cloud's radiative Green functions. A direct data product of WAIL is the distribution of photon path lengths resulting from multiple scattering in the cloud. Following insights from diffusion theory, we can use the measured Green functions to infer the physical thickness and optical depth of the cloud layer. WAIL is notable in that it is applicable to optically thick clouds, a regime in which traditional lidar is reduced to ceilometry. Section 2 covers the up-to-date evolution of the nighttime WAIL instrument at LANL. Section 3 reports our progress towards daytime capability for WAIL, an important extension to full diurnal cycle monitoring by means of an ultra-narrow magneto-optic atomic line filter. Section 4 describes briefly how the important cloud properties can be inferred from WAIL signals.

  19. Zen of cloud learning cloud computing by examples on Microsoft Azure

    CERN Document Server

    Bai, Haishi

    2014-01-01

    Zen of Cloud: Learning Cloud Computing by Examples on Microsoft Azure provides comprehensive coverage of the essential theories behind cloud computing and the Windows Azure cloud platform. Sharing the author's insights gained while working at Microsoft's headquarters, it presents nearly 70 end-to-end examples with step-by-step guidance on implementing typical cloud-based scenarios.The book is organized into four sections: cloud service fundamentals, cloud solutions, devices and cloud, and system integration and project management. Each chapter contains detailed exercises that provide readers w

  20. Is cloud computing finally beginning to mature?

    Directory of Open Access Journals (Sweden)

    Dimitrios Zissis

    2012-10-01

    Full Text Available The buzz term that came into popularity in the beginning of 2006 to describe an innovative IT deployment architecture, originated from the cloud metaphor that was used to represent the Internet in various network diagrams as early as the 1990s. In a short period of time after the term appeared, cloud solutions were being rapidly marketed by many IT companies and various new buzz words came into vogue such as "cloud in a can", "cloud bursting", and we suddenly had “blue clouds”, “green clouds”, “white label cloud services” and many others. We witnessed what is now being labeled as "cloud washing", the attempts of many vendors to strap the cloud term onto their traditional products, which became the source of huge disambiguation, conflicts and misunderstandings. Today, the term “cloud computing” is everywhere. A quick search on Google for the term “cloud computing” will return 267 million search results. Cloud computing is being marketed as the complex-free efficient method of accessing huge amounts of computing and storage as a service. Behind the curtains though, cloud computing has often been called a huge leap of faith and concerns were fuelled when reports started to surface of random failures (e.g. power outages and shortcomings of cloud infrastructures. Small black clouds of uncertainty have appeared in the otherwise clear skies of cloud computing