Impact of Nagasaki atomic bomb exposure on myelodysplastic syndrome patients who are treated with azacitidine.

Science.gov (United States)

Jo, Tatsuro; Horio, Kensuke; Shigematsu, Kazuto

2015-05-01

High-dose radiation exposure greatly increases the risk of myelodysplastic syndromes (MDS), however the clinical characteristics of MDS among atomic bomb survivors have not been thoroughly investigated to date. We designed this study to identify these characteristics. We retrospectively evaluated data from 13 atomic bomb survivors with MDS and 15 elderly patients with de novo MDS who were diagnosed between April 2011 and April 2013 at the Nagasaki Genbaku Hospital. All patients were treated with azacitidine (AZA; a hypomethylating agent) and overall survival rates were estimated. No clear difference was observed in the clinical response to AZA between the two groups. However, atomic bomb survivors had a survival disadvantage, independent of their karyotype. Minute genetic alterations caused by exposure to atomic radiation can adversely affect the response to AZA, even 66 years after the exposure. Further studies are required to clarify the mechanisms underlying this phenomenon. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Transformation of Real Spherical Harmonics under Rotations

Science.gov (United States)

Romanowski, Z.; Krukowski, St.; Jalbout, A. F.

2008-08-01

The algorithm rotating the real spherical harmonics is presented. The convenient and ready to use formulae for l = 0, 1, 2, 3 are listed. The rotation in R3 space is determined by the rotation axis and the rotation angle; the Euler angles are not used. The proposed algorithm consists of three steps. (i) Express the real spherical harmonics as the linear combination of canonical polynomials. (ii) Rotate the canonical polynomials. (iii) Express the rotated canonical polynomials as the linear combination of real spherical harmonics. Since the three step procedure can be treated as a superposition of rotations, the searched rotation matrix for real spherical harmonics is a product of three matrices. The explicit formulae of matrix elements are given for l = 0, 1, 2, 3, what corresponds to s, p, d, f atomic orbitals.

Real time simulator for material testing reactor

Energy Technology Data Exchange (ETDEWEB)

Takemoto, Noriyuki; Imaizumi, Tomomi; Izumo, Hironobu; Hori, Naohiko; Suzuki, Masahide [Japan Atomic Energy Agency, Oarai Research and Development Center, Oarai, Ibaraki (Japan); Ishitsuka, Tatsuo; Tamura, Kazuo [ITOCHU Techno-Solutions Corp., Tokyo (Japan)

2012-03-15

Japan Atomic Energy Agency (JAEA) is now developing a real time simulator for a material testing reactor based on Japan Materials Testing Reactor (JMTR). The simulator treats reactor core system, primary and secondary cooling system, electricity system and irradiation facility systems. Possible simulations are normal reactor operation, unusual transient operation and accidental operation. The developed simulator also contains tool to revise/add facility in it for the future development. (author)

Real time simulator for material testing reactor

International Nuclear Information System (INIS)

Takemoto, Noriyuki; Imaizumi, Tomomi; Izumo, Hironobu; Hori, Naohiko; Suzuki, Masahide; Ishitsuka, Tatsuo; Tamura, Kazuo

2012-01-01

Japan Atomic Energy Agency (JAEA) is now developing a real time simulator for a material testing reactor based on Japan Materials Testing Reactor (JMTR). The simulator treats reactor core system, primary and secondary cooling system, electricity system and irradiation facility systems. Possible simulations are normal reactor operation, unusual transient operation and accidental operation. The developed simulator also contains tool to revise/add facility in it for the future development. (author)

Directed Atom-by-Atom Assembly of Dopants in Silicon.

Science.gov (United States)

Hudak, Bethany M; Song, Jiaming; Sims, Hunter; Troparevsky, M Claudia; Humble, Travis S; Pantelides, Sokrates T; Snijders, Paul C; Lupini, Andrew R

2018-05-17

The ability to controllably position single atoms inside materials is key for the ultimate fabrication of devices with functionalities governed by atomic-scale properties. Single bismuth dopant atoms in silicon provide an ideal case study in view of proposals for single-dopant quantum bits. However, bismuth is the least soluble pnictogen in silicon, meaning that the dopant atoms tend to migrate out of position during sample growth. Here, we demonstrate epitaxial growth of thin silicon films doped with bismuth. We use atomic-resolution aberration-corrected imaging to view the as-grown dopant distribution and then to controllably position single dopants inside the film. Atomic-scale quantum-mechanical calculations corroborate the experimental findings. These results indicate that the scanning transmission electron microscope is of particular interest for assembling functional materials atom-by-atom because it offers both real-time monitoring and atom manipulation. We envision electron-beam manipulation of atoms inside materials as an achievable route to controllable assembly of structures of individual dopants.

Cell-killing efficiency and number of platinum atoms binding to DNA, RNA and protein molecules of HeLa cells treated with combinations of hyperthermia and carboplatin

International Nuclear Information System (INIS)

Akaboshi, M.; Kawai, K.; Tanaka, Y.; Takada, J.; Sumino, T.

1999-01-01

The effect of hyperthermia on the cell killing efficiency of Pt atoms binding to DNA, RNA and protein molecules of HeLa cells treated with cis-diamine(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA) was examined. HeLa S-3 cells were treated with 195m Pt-radiolabeled CBDCA for 60 minutes at various temperatures, and the relationship between the lethal effect and the number of Pt atoms binding to DNA, RNA and proteins was examined. The mean lethal concentration (D 0 ) of carboplatin for a 60 min-treatment at 0, 25, 37, 40, 42 and 44 deg C was 671.2, 201.5, 67.3, 33.4, 20.2 and 15.6 μM, respectively. By using identically treated cells, the number of Pt-atoms combined with DNA, RNA and protein molecules were determined in the subcellular fractions. Thus, the D 0 's given as the drug concentrations were replaced with the number of Pt-atoms combined in each fraction. Then, the cell-killing efficiency of the Pt atom was expressed as the reciprocal of the number of Pt-atoms combined and was calculated for each molecule. The efficiency for DNA molecules was 0.699, 1.42, 2.65, 4.84, 7.74 and 8.28x10 4 nucleotides, respectively, for the conditions described above. From 0 to 44 deg C, the cell-killing efficiency of Pt atoms increased by a factor of 11.9. (author)

Exposure to an atomic bomb explosion is a risk factor for in-hospital death after esophagectomy to treat esophageal cancer.

Science.gov (United States)

Nakashima, Y; Takeishi, K; Guntani, A; Tsujita, E; Yoshinaga, K; Matsuyama, A; Hamatake, M; Maeda, T; Tsutsui, S; Matsuda, H; Ishida, T

2015-01-01

Esophagectomy, one of the most invasive of all gastrointestinal operations, is associated with a high frequency of postoperative complications and in-hospital mortality. The purpose of the present study was to determine whether exposure to the atomic bomb explosion at Hiroshima in 1945 might be a preoperative risk factor for in-hospital mortality after esophagectomy in esophageal cancer patients. We thus reviewed the outcomes of esophagectomy in 31 atomic bomb survivors with esophageal cancer and 96 controls (also with cancer but without atomic bomb exposure). We compared the incidences of postoperative complications and in-hospital mortality. Of the clinicopathological features studied, mean patient age was significantly higher in atomic bomb survivors than in controls. Of the postoperative complications noted, atomic bomb survivors experienced a longer mean period of endotracheal intubation and higher incidences of severe pulmonary complications, severe anastomotic leakage, and surgical site infection. The factors associated with in-hospital mortality were exposure to the atomic bomb explosion, pulmonary comorbidities, and electrocardiographic abnormalities. Multivariate analysis revealed that exposure to the atomic bomb explosion was an independent significant preoperative risk factor for in-hospital mortality. Exposure to the atomic bomb explosion is thus a preoperative risk factor for in-hospital death after esophagectomy to treat esophageal cancer. © 2013 Wiley Periodicals, Inc. and the International Society for Diseases of the Esophagus.

Purification of ammonia-containing trap waters from atomic power plant by ozone treatment

International Nuclear Information System (INIS)

Grachok, M.A.; Prokudina, S.A.; Shulyat'ev, M.I.

1990-01-01

The aim of research was to study the process of ozonation of ammonia-containing trap waters from the Kursk Atomic Power Plant both on the model solutions and on real ones. Different factors (pH of the medium, temperature, concentration of the initial substances) have been studied for their effect on ozonation of aqueous ammonia solutions, model solutions of trap waters from the Kursk Atomic Power Plant as well as ammonia-containing trap waters and liquid radioactive wastes delivered to special water treatment at the Kursk Atomic Power Plant. It is shown that in all the cases the highest rate of ammonia oxidation by ozone is observed in the alkaline medium (pH 1.4-11.0) and at 55 deg C. The obtained results have shown that a method of ozonation followed by evaporation of water to be purified can be used to treat ammonia-containing waters from atomic power plant

Characterization of chemically and enzymatically treated hemp fibres using atomic force microscopy and spectroscopy

Energy Technology Data Exchange (ETDEWEB)

George, Michael; Mussone, Paolo G. [Biorefining Conversions and Fermentations Laboratory, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada T6E 2P5 (Canada); Abboud, Zeinab [Biorefining Conversions and Fermentations Laboratory, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada T6E 2P5 (Canada); Department of Physics, University of Guelph, Guelph, ON, Canada N1G 2W1 (Canada); Bressler, David C., E-mail: david.bressler@ualberta.ca [Biorefining Conversions and Fermentations Laboratory, Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, Canada T6E 2P5 (Canada)

2014-09-30

The mechanical and moisture resistance properties of natural fibre reinforced composites are dependent on the adhesion between the matrix of choice and the fibre. The main goal of this study was to investigate the effect of NaOH swelling of hemp fibres prior to enzymatic treatment and a novel chemical sulfonic acid method on the physical properties of hemp fibres. The colloidal properties of treated hemp fibres were studied exclusively using an atomic force microscope. AFM imaging in tapping mode revealed that each treatment rendered the surface topography of the hemp fibres clean and exposed the individual fibre bundles. Hemp fibres treated with laccase had no effect on the surface adhesion forces measured. Interestingly, mercerization prior to xylanase + cellulase and laccase treatments resulted in greater enzyme access evident in the increased adhesion force measurements. Hemp fibres treated with sulfonic acid showed an increase in surface de-fibrillation and smoothness. A decrease in adhesion forces for 4-aminotoulene-3-sulfonic acid (AT3S) treated fibres suggested a reduction in surface polarity. This work demonstrated that AFM can be used as a tool to estimate the surface forces and roughness for modified fibres and that enzymatic coupled with chemical methods can be used to improve the surface properties of natural fibres for composite applications. Further, this work is one of the first that offers some insight into the effect of mercerization prior to enzymes and the effect on the surface topography. AFM will be used to selectively screen treated fibres for composite applications based on the adhesion forces associated with the colloidal interface between the AFM tip and the fibre surfaces.

Simulated non-contact atomic force microscopy for GaAs surfaces based on real-space pseudopotentials

International Nuclear Information System (INIS)

Kim, Minjung; Chelikowsky, James R.

2014-01-01

We simulate non-contact atomic force microscopy (AFM) with a GaAs(1 1 0) surface using a real-space ab initio pseudopotential method. While most ab initio simulations include an explicit model for the AFM tip, our method does not introduce the tip modeling step. This approach results in a considerable reduction of computational work, and also provides complete AFM images, which can be directly compared to experiment. By analyzing tip-surface interaction forces in both our results and previous ab initio simulations, we find that our method provides very similar force profile to the pure Si tip results. We conclude that our method works well for systems in which the tip is not chemically active.

Single-Atom Gating of Quantum State Superpositions

Energy Technology Data Exchange (ETDEWEB)

Moon, Christopher

2010-04-28

The ultimate miniaturization of electronic devices will likely require local and coherent control of single electronic wavefunctions. Wavefunctions exist within both physical real space and an abstract state space with a simple geometric interpretation: this state space - or Hilbert space - is spanned by mutually orthogonal state vectors corresponding to the quantized degrees of freedom of the real-space system. Measurement of superpositions is akin to accessing the direction of a vector in Hilbert space, determining an angle of rotation equivalent to quantum phase. Here we show that an individual atom inside a designed quantum corral1 can control this angle, producing arbitrary coherent superpositions of spatial quantum states. Using scanning tunnelling microscopy and nanostructures assembled atom-by-atom we demonstrate how single spins and quantum mirages can be harnessed to image the superposition of two electronic states. We also present a straightforward method to determine the atom path enacting phase rotations between any desired state vectors. A single atom thus becomes a real-space handle for an abstract Hilbert space, providing a simple technique for coherent quantum state manipulation at the spatial limit of condensed matter.

Real time drift measurement for colloidal probe atomic force microscope: a visual sensing approach

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuliang, E-mail: wangyuliang@buaa.edu.cn; Bi, Shusheng [Robotics Institute, School of Mechanical Engineering and Automation, Beihang University, Beijing 100191 (China); Wang, Huimin [Department of Materials Science and Engineering, The Ohio State University, 2041 College Rd., Columbus, OH 43210 (United States)

2014-05-15

Drift has long been an issue in atomic force microscope (AFM) systems and limits their ability to make long time period measurements. In this study, a new method is proposed to directly measure and compensate for the drift between AFM cantilevers and sample surfaces in AFM systems. This was achieved by simultaneously measuring z positions for beads at the end of an AFM colloidal probe and on sample surface through an off-focus image processing based visual sensing method. The working principle and system configuration are presented. Experiments were conducted to validate the real time drift measurement and compensation. The implication of the proposed method for regular AFM measurements is discussed. We believe that this technique provides a practical and efficient approach for AFM experiments requiring long time period measurement.

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...

Real space process algebra

NARCIS (Netherlands)

Bergstra, J.A.; Baeten, J.C.M.

1993-01-01

The real time process algebra of Baeten and Bergstra [Formal Aspects of Computing, 3, 142-188 (1991)] is extended to real space by requiring the presence of spatial coordinates for each atomic action, in addition to the required temporal attribute. It is found that asynchronous communication

Microstructural evolution and mechanical properties of differently heat-treated binder jet printed samples from gas- and water-atomized alloy 625 powders

International Nuclear Information System (INIS)

Mostafaei, Amir; Toman, Jakub; Stevens, Erica L.; Hughes, Eamonn T.; Krimer, Yuval L.; Chmielus, Markus

2017-01-01

In this study, we investigate the effect of powders resulting from different atomization methods on properties of binder jet printed and heat-treated samples. Air-melted gas atomized (GA) and water atomized (WA) nickel-based alloy 625 powders were used to binder jet print samples for a detailed comparative study on microstructural evolution and mechanical properties. GA printed samples achieved higher sintering density (99.2%) than WA samples (95.0%) due to differences in powder morphology and chemistry. Grain sizes of GA and WA samples at their highest density were 89 ± 21 μm and 88 ± 26 μm, respectively. Mechanical tests were conducted on optimally sintered samples and sintered plus aged samples; aging further improved microstructure and mechanical properties. This study shows that microstructural evolution (densification, and carbide, oxide and intermetallic phase formation) is very different for GA and WA binder jet printed and heat-treated samples. This difference in microstructural evolution results in different mechanical properties with the superior sintered and aged GA specimen reaching a hardness of 327 ± 7 HV_0_._1, yield strength of 394 ± 15 MPa, and ultimate tensile strength of 718 ± 14 MPa which are higher than cast alloy 625 values.

Light absorption during alkali atom-noble gas atom interactions at thermal energies: a quantum dynamics treatment.

Science.gov (United States)

Pacheco, Alexander B; Reyes, Andrés; Micha, David A

2006-10-21

The absorption of light during atomic collisions is treated by coupling electronic excitations, treated quantum mechanically, to the motion of the nuclei described within a short de Broglie wavelength approximation, using a density matrix approach. The time-dependent electric dipole of the system provides the intensity of light absorption in a treatment valid for transient phenomena, and the Fourier transform of time-dependent intensities gives absorption spectra that are very sensitive to details of the interaction potentials of excited diatomic states. We consider several sets of atomic expansion functions and atomic pseudopotentials, and introduce new parametrizations to provide light absorption spectra in good agreement with experimentally measured and ab initio calculated spectra. To this end, we describe the electronic excitation of the valence electron of excited alkali atoms in collisions with noble gas atoms with a procedure that combines l-dependent atomic pseudopotentials, including two- and three-body polarization terms, and a treatment of the dynamics based on the eikonal approximation of atomic motions and time-dependent molecular orbitals. We present results for the collision induced absorption spectra in the Li-He system at 720 K, which display both atomic and molecular transition intensities.

An atomic orbital based real-time time-dependent density functional theory for computing electronic circular dichroism band spectra

Energy Technology Data Exchange (ETDEWEB)

Goings, Joshua J.; Li, Xiaosong, E-mail: xsli@uw.edu [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States)

2016-06-21

One of the challenges of interpreting electronic circular dichroism (ECD) band spectra is that different states may have different rotatory strength signs, determined by their absolute configuration. If the states are closely spaced and opposite in sign, observed transitions may be washed out by nearby states, unlike absorption spectra where transitions are always positive additive. To accurately compute ECD bands, it is necessary to compute a large number of excited states, which may be prohibitively costly if one uses the linear-response time-dependent density functional theory (TDDFT) framework. Here we implement a real-time, atomic-orbital based TDDFT method for computing the entire ECD spectrum simultaneously. The method is advantageous for large systems with a high density of states. In contrast to previous implementations based on real-space grids, the method is variational, independent of nuclear orientation, and does not rely on pseudopotential approximations, making it suitable for computation of chiroptical properties well into the X-ray regime.

Overall Survival of Patients with Locally Advanced or Metastatic Esophageal Squamous Cell Carcinoma Treated with Nimotuzumab in the Real World.

Science.gov (United States)

Saumell, Yaimarelis; Sanchez, Lizet; González, Sandra; Ortiz, Ramón; Medina, Edadny; Galán, Yaima; Lage, Agustin

2017-12-01

Despite improvements in surgical techniques and treatments introduced into clinical practice, the overall survival of patients with esophageal squamous cell carcinoma remains low. Several epidermal growth factor receptor inhibitors are being evaluated in the context of clinical trials, but there is little evidence of effectiveness in real-world conditions. This study aimed at assessing the effectiveness of nimotuzumab combined with onco-specific treatment in Cuban real-life patients with locally advanced or metastatic esophageal squamous cell carcinoma. A comparative and retrospective effectiveness study was performed. The 93 patients treated with nimotuzumab were matched, with use of propensity score matching, with patients who received a diagnosis of locally advanced or metastatic squamous cell carcinoma of the esophagus in three Cuban provinces reported between 2011 and 2015 to the National Cancer Registry. The Kaplan-Meier method was used to estimate event-time distributions. Log-rank statistics were used for comparisons of overall survival between groups. A two-component mixture model assuming a Weibull distribution was fitted to assess the effect of nimotuzumab on short-term and long-term survival populations. There was an increase in median overall survival in patients treated with nimotuzumab (11.9 months versus 6.5 months without treatment) and an increase in the 1-year survival rate (54.0% versus 21.9% without treatment). The 2-year survival rates were 21.1% for patients treated with nimotuzumab and 0% in the untreated cohort. There were statistically significant differences in survival between groups treated and not treated with nimotuzumab, both in the short-term survival population (6.0 months vs 4.0 months, p = 0.009) and in the long-term survival population (18.0 months vs 11.0 months, p = 0.001). Our study shows that nimotuzumab treatment concurrent with chemoradiotherapy increases the survival of real-world patients with locally advanced

Electric field imaging of single atoms

Science.gov (United States)

Shibata, Naoya; Seki, Takehito; Sánchez-Santolino, Gabriel; Findlay, Scott D.; Kohno, Yuji; Matsumoto, Takao; Ishikawa, Ryo; Ikuhara, Yuichi

2017-01-01

In scanning transmission electron microscopy (STEM), single atoms can be imaged by detecting electrons scattered through high angles using post-specimen, annular-type detectors. Recently, it has been shown that the atomic-scale electric field of both the positive atomic nuclei and the surrounding negative electrons within crystalline materials can be probed by atomic-resolution differential phase contrast STEM. Here we demonstrate the real-space imaging of the (projected) atomic electric field distribution inside single Au atoms, using sub-Å spatial resolution STEM combined with a high-speed segmented detector. We directly visualize that the electric field distribution (blurred by the sub-Å size electron probe) drastically changes within the single Au atom in a shape that relates to the spatial variation of total charge density within the atom. Atomic-resolution electric field mapping with single-atom sensitivity enables us to examine their detailed internal and boundary structures. PMID:28555629

Experimental determination of the real elements of the density matrix of H(n=3) atoms produced in 20--100-keV collisions of H+ on Kr

International Nuclear Information System (INIS)

Seifert, N.; Gibson, N.D.; Risley, J.S.

1995-01-01

In continuation of our previous work, charge transfer processes occurring in protons on rare-gas-atom collisions have been investigated. Diagonal and real off-diagonal coherence elements of the density matrix for H(n=3) atoms produced in 20--100-keV electron-capture collisions with Kr atoms are experimentally determined by analyzing the Balmer-α light from the decay of H atoms from the (n=3) state to the (n=2) state. The intensity and polarization of the emitted light are measured as functions of an axially symmetric electric field in the collision region. These data are fitted to a numerical model of the H atom in an electric field in order to extract density-matrix elements. The results are compared to previous studies of H + on He and Ar. The collisionally produced dipole moment of the H(n=3) atom decreases for increasing atomic number of the rare-gas target atoms, which indicates that the final phase of the collision process is not essential for the formation of the dipole moment. This physical picture is further supported by our alignment data. Absolute cross sections for charge transfer to the 3s, 3p, and 3d levels are presented as well

The fundamentals of atomic and molecular physics

CERN Document Server

Brooks, Robert L

2013-01-01

The Fundamentals of Atomic and Molecular Physics is intended as an introduction to the field for advanced undergraduates who have taken quantum mechanics. Each chapter builds upon the previous, using the same tools and methods throughout. As the students progress through the book, their ability to use these tools will steadily increase, along with their confidence in their efficacy. The book treats the two-electron atom as the simplest example of the many-electron atom—as opposed to using techniques that are not applicable to many-electron atoms—so that it is unnecessary to develop additional equations when turning to multielectron atoms, such as carbon. External fields are treated using both perturbation theory and direct diagonalization and spontaneous emission is developed from first principles. Only diatomic molecules are considered with the hydrogen molecular ion and neutral molecule treated in some detail. This comprehensive coverage of the quantum mechanics of complex atoms and simple diatomic mole...

Laser Control of Atoms and Molecules

CERN Document Server

Letkhov, V S

2007-01-01

This text treats laser light as a universal tool to control matter at the atomic and molecular level, one of the most exciting applications of lasers. Lasers can heat matter, cool atoms to ultra-low temperatures where they show quantum collective behaviour, and can act selectively on specific atoms and molecules for their detection and separation.

Fidelity imaging for atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Ghosal, Sayan, E-mail: ghos0087@umn.edu; Salapaka, Murti, E-mail: murtis@umn.edu [Nanodynamics Systems Laboratory, Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

2015-01-05

Atomic force microscopy is widely employed for imaging material at the nanoscale. However, real-time measures on image reliability are lacking in contemporary atomic force microscopy literature. In this article, we present a real-time technique that provides an image of fidelity for a high bandwidth dynamic mode imaging scheme. The fidelity images define channels that allow the user to have additional authority over the choice of decision threshold that facilitates where the emphasis is desired, on discovering most true features on the sample with the possible detection of high number of false features, or emphasizing minimizing instances of false detections. Simulation and experimental results demonstrate the effectiveness of fidelity imaging.

The atom in human thought history

International Nuclear Information System (INIS)

Pullman, B.

1995-01-01

This book speaks of atom history. From the ancient Greece until now, science debated around the question for or against the atom conception of universe. In this book of sciences history, the author goes over the major events of this intellectual joust with a real pedagogic care, from Democrite, Aristote, Platon to Planck, Bohr, Einstein, Schroedinger and some others

Optical atomic phase reference and timing

Science.gov (United States)

Hollberg, L.; Cornell, E. H.; Abdelrahmann, A.

2017-06-01

Atomic clocks based on laser-cooled atoms have made tremendous advances in both accuracy and stability. However, advanced clocks have not found their way into widespread use because there has been little need for such high performance in real-world/commercial applications. The drive in the commercial world favours smaller, lower-power, more robust compact atomic clocks that function well in real-world non-laboratory environments. Although the high-performance atomic frequency references are useful to test Einstein's special relativity more precisely, there are not compelling scientific arguments to expect a breakdown in special relativity. On the other hand, the dynamics of gravity, evidenced by the recent spectacular results in experimental detection of gravity waves by the LIGO Scientific Collaboration, shows dramatically that there is new physics to be seen and understood in space-time science. Those systems require strain measurements at less than or equal to 10-20. As we discuss here, cold atom optical frequency references are still many orders of magnitude away from the frequency stability that should be achievable with narrow-linewidth quantum transitions and large numbers of very cold atoms, and they may be able to achieve levels of phase stability, ΔΦ/Φtotal ≤ 10-20, that could make an important impact in gravity wave science. This article is part of the themed issue 'Quantum technology for the 21st century'.

Coexistence of photonic and atomic Bose-Einstein condensates in ideal atomic gases

Directory of Open Access Journals (Sweden)

N. Boichenko

2015-12-01

Full Text Available We have studied conditions of photon Bose-Einstein condensate formation that is in thermodynamic equilibrium with ideal gas of two-level Bose atoms below the degeneracy temperature. Equations describing thermodynamic equilibrium in the system were formulated; critical temperatures and densities of photonic and atomic gas subsystems were obtained analytically. Coexistence conditions of these photonic and atomic Bose-Einstein condensates were found. There was predicted the possibility of an abrupt type of photon condensation in the presence of Bose condensate of ground-state atoms: it was shown that the slightest decrease of the temperature could cause a significant gathering of photons in the condensate. This case could be treated as a simple model of the situation known as "stopped light" in cold atomic gas. We also showed how population inversion of atomic levels can be created by lowering the temperature. The latter situation looks promising for light accumulation in atomic vapor at very low temperatures.

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

Super-Coulombic atom-atom interactions in hyperbolic media

Science.gov (United States)

Cortes, Cristian L.; Jacob, Zubin

2017-01-01

Dipole-dipole interactions, which govern phenomena such as cooperative Lamb shifts, superradiant decay rates, Van der Waals forces and resonance energy transfer rates, are conventionally limited to the Coulombic near-field. Here we reveal a class of real-photon and virtual-photon long-range quantum electrodynamic interactions that have a singularity in media with hyperbolic dispersion. The singularity in the dipole-dipole coupling, referred to as a super-Coulombic interaction, is a result of an effective interaction distance that goes to zero in the ideal limit irrespective of the physical distance. We investigate the entire landscape of atom-atom interactions in hyperbolic media confirming the giant long-range enhancement. We also propose multiple experimental platforms to verify our predicted effect with phonon-polaritonic hexagonal boron nitride, plasmonic super-lattices and hyperbolic meta-surfaces as well. Our work paves the way for the control of cold atoms above hyperbolic meta-surfaces and the study of many-body physics with hyperbolic media.

Nanoporous silver cathode surface treated by atomic layer deposition of CeO_x for low-temperature solid oxide fuel cells

International Nuclear Information System (INIS)

Neoh, Ke Chean; Han, Gwon Deok; Kim, Manjin; Kim, Jun Woo; Choi, Hyung Jong; Park, Suk Won; Shim, Joon Hyung

2016-01-01

We evaluated the performance of solid oxide fuel cells (SOFCs) with a 50 nm thin silver (Ag) cathode surface treated with cerium oxide (CeO_x) by atomic layer deposition (ALD). The performances of bare and ALD-treated Ag cathodes were evaluated on gadolinia-doped ceria (GDC) electrolyte supporting cells with a platinum (Pt) anode over 300 °C–450 °C. Our work confirms that ALD CeO_x treatment enhances cathodic performance and thermal stability of the Ag cathode. The performance difference between cells using a Ag cathode optimally treated with an ALD CeO_x surface and a reference Pt cathode is about 50% at 450 °C in terms of fuel cell power output in our experiment. The bare Ag cathode completely agglomerated into islands during fuel cell operation at 450 °C, while the ALD CeO_x treatment effectively protects the porosity of the cathode. We also discuss the long-term stability of ALD CeO_x-treated Ag cathodes related to the microstructure of the layers. (paper)

Small-angle scattering of ions or atoms by atomic hydrogen

International Nuclear Information System (INIS)

Franco, V.

1982-01-01

A theory for small-angle scattering of arbitrary medium- or high-energy atoms or ions by atomic hydrogen is described. Results are obtained in terms of the known closed-form and easily calculable Glauber-approximation scattering amplitudes for electron-hydrogen collisions and for collisions between the nucleus (treated as one charged particle) of the ion or atom and the hydrogen atom, and in terms of the transition form factor of the arbitrary ion or atom. Applications are made to the angular differential cross sections for the excitation of atomic hydrogen to its n = 2 states by singly charged ground-state helium ions having velocities of roughly between 1/2 and 1 a.u. The differential cross sections are obtained in terms of electron-hydrogen amplitudes and the known He + ground-state form factor. Comparisons are made with other calculations and with recent measurements. The results are in good agreement with the data. It is seen that the effect of the He + electron is to produce significant constructive interference at most energies

Line splitting and modified atomic decay of atoms coupled with N quantized cavity modes

Science.gov (United States)

Zhu, Yifu

1992-05-01

We study the interaction of a two-level atom with N non-degenerate quantized cavity modes including dissipations from atomic decay and cavity damps. In the strong coupling regime, the absorption or emission spectrum of weakly excited atom-cavity system possesses N + 1 spectral peaks whose linewidths are the weighted averages of atomic and cavity linewidths. The coupled system shows subnatural (supernatural) atomic decay behavior if the photon loss rates from the N cavity modes are smaller (larger) than the atomic decay rate. If N cavity modes are degenerate, they can be treated effectively as a single mode. In addition, we present numerical calculations for N = 2 to characterize the system evolution from the weak coupling to strong coupling limits.

Observation of nuclear track in organic material by atomic force microscopy in real time during etching

CERN Document Server

Palmino, F; Labrune, J C

1999-01-01

The developments of Atomic Force Microscopy (AFM) allow to investigated solid surfaces with a nanometer scale. These techniques are useful methods allowing direct observation of surface morphologies. Particularly in the nuclear track fields, they offer a new tool to give many new informations on track formation. In this paper we present the preliminary results of a new use of this technique to characterize continuously the formation of the revealed track in a cellulose nitrate detector (LR115) after an alpha particle irradiation. For that, a specific cell has been used to observe, by nano-observations, the evolution of track shapes simultaneously with chemical treatment. Thus, the track shape evolution has been studied; visualizing the evolution of the tracks in real time, in situ during the chemical etching process.

One-atom detection and statistical studies with resonance ionization spectroscopy

International Nuclear Information System (INIS)

Payne, M.G.; Hurst, G.S.

1982-01-01

To learn how to take matter apart atom-by-atom and to count each atom according to its type, regardless of its initial chemical or physical state, is presumably a worthy goal in scientific research. The advent of the laser created real hope that these aspirations will be realized. The counting of atoms is not merely an intellectual exercise set apart from real-world applications. On the contrary, even though the capability is scarcely more than five years old, practical applications have been made in many fields of chemistry, physics, the environment, and industry. In this lecture we wish to review how the laser made possible the counting of atoms and how this capability has been put to use in situations where atoms are free to react chemically as they diffuse through a medium. Fluctuation phenomena and statistical mechanics can also be examined in these situations

Integrated real-time control strategy in multi-tank A2O process for biological nutrient removal treating real domestic wastewater

Directory of Open Access Journals (Sweden)

Saad Abualhail

2017-02-01

Full Text Available An integrated real-time anaerobic–anoxic/oxic (A2O operated with multi-tank called IMT–A2O process was designed and operated with fluctuating influent loads for biological nutrient removal for treating real domestic wastewater. IMT–A2O process, a “phased isolation tank” technology, varies both aeration pattern and flow path in a continuous flow multi-tank system to force fluctuation of organic and nutrient concentrations in process reactors. Using an eight-phase cycle, desired biochemical transformations, are accomplished at different times in the same tank. On-line sensors (pH, ORP, and DO were used as real-time control parameters to adjust the duration of each operational phase in the IMT–A2O process. The control system is an algorithm that automatically adjusts the cycle length to the influent wastewater characteristics according to the end points. It was found that on-line sensor values of pH, ORP, and DO were somehow related with the dynamic behaviors of nutrient concentrations in IMT–A2O. The algorithm acts in the reaction phases of the IMT–A2O cycle using ORP and pH break points of tank one to distinguish the end of denitrification and the beginning of phosphorus release, pH break point of tank two to control the end of denitrification and beginning of phosphorus release and a sudden increase in DO pattern, pH break point and ORP to control phosphorus uptake and the end of the nitrification process. Although the fluctuations in raw wastewater concentration are extreme; an influent with a low C/N ratio is deficient in organic carbon, and a low carbon source level can limit the overall biological denitrification process, the average removal efficiencies achieved for COD, ammonia–nitrogen, total nitrogen and total phosphorus were not less than 76.11%, 87.78%, 76.45% and 83.75%, respectively, using the integrated real-time control strategy. The integrated IMT–A2O exhibited a better performance in nutrient removal than the

Optical atomic phase reference and timing.

Science.gov (United States)

Hollberg, L; Cornell, E H; Abdelrahmann, A

2017-08-06

Atomic clocks based on laser-cooled atoms have made tremendous advances in both accuracy and stability. However, advanced clocks have not found their way into widespread use because there has been little need for such high performance in real-world/commercial applications. The drive in the commercial world favours smaller, lower-power, more robust compact atomic clocks that function well in real-world non-laboratory environments. Although the high-performance atomic frequency references are useful to test Einstein's special relativity more precisely, there are not compelling scientific arguments to expect a breakdown in special relativity. On the other hand, the dynamics of gravity, evidenced by the recent spectacular results in experimental detection of gravity waves by the LIGO Scientific Collaboration, shows dramatically that there is new physics to be seen and understood in space-time science. Those systems require strain measurements at less than or equal to 10 -20 As we discuss here, cold atom optical frequency references are still many orders of magnitude away from the frequency stability that should be achievable with narrow-linewidth quantum transitions and large numbers of very cold atoms, and they may be able to achieve levels of phase stability, Δ Φ / Φ total  ≤ 10 -20 , that could make an important impact in gravity wave science.This article is part of the themed issue 'Quantum technology for the 21st century'. © 2017 The Author(s).

Atom chips in the real world: the effects of wire corrugation

Science.gov (United States)

Schumm, T.; Estève, J.; Figl, C.; Trebbia, J.-B.; Aussibal, C.; Nguyen, H.; Mailly, D.; Bouchoule, I.; Westbrook, C. I.; Aspect, A.

2005-02-01

We present a detailed model describing the effects of wire corrugation on the trapping potential experienced by a cloud of atoms above a current carrying micro wire. We calculate the distortion of the current distribution due to corrugation and then derive the corresponding roughness in the magnetic field above the wire. Scaling laws are derived for the roughness as a function of height above a ribbon shaped wire. We also present experimental data on micro wire traps using cold atoms which complement some previously published measurements [CITE] and which demonstrate that wire corrugation can satisfactorily explain our observations of atom cloud fragmentation above electroplated gold wires. Finally, we present measurements of the corrugation of new wires fabricated by electron beam lithography and evaporation of gold. These wires appear to be substantially smoother than electroplated wires.

Cavitation and primary atomization in real injectors at low injection pressure condition

Science.gov (United States)

Dumouchel, Christophe; Leboucher, Nicolas; Lisiecki, Denis

2013-06-01

This experimental work investigates the influence of the geometry of GDI devices on primary atomization processes under low injection pressure and reduced back pressure. These pressure conditions ensure cavitating flows and observable atomization processes. Measurements include mass flux, structure velocity from high-speed visualizations and spray characterization with a laser diffraction technique. Super-cavitation regime and cavitation string, which have their own influence on the mass flux, develop independently in different injector regions. These regimes impact the flow pattern in the orifice and the subsequent atomization process. A possible interaction between cavitation string and super-cavitation is found to promote a hydraulic-flip-like regime and to deteriorate atomization quality. As far as the geometry of the injector is concerned, the profile of the orifice inlet and the roughness of the sac volume region are found to be important geometrical characteristics.

Revealing the correlation between real-space structure and chiral magnetic order at the atomic scale

Science.gov (United States)

Hauptmann, Nadine; Dupé, Melanie; Hung, Tzu-Chao; Lemmens, Alexander K.; Wegner, Daniel; Dupé, Bertrand; Khajetoorians, Alexander A.

2018-03-01

We image simultaneously the geometric, the electronic, and the magnetic structures of a buckled iron bilayer film that exhibits chiral magnetic order. We achieve this by combining spin-polarized scanning tunneling microscopy and magnetic exchange force microscopy (SPEX) to independently characterize the geometric as well as the electronic and magnetic structures of nonflat surfaces. This new SPEX imaging technique reveals the geometric height corrugation of the reconstruction lines resulting from strong strain relaxation in the bilayer, enabling the decomposition of the real-space from the electronic structure at the atomic level and the correlation with the resultant spin-spiral ground state. By additionally utilizing adatom manipulation, we reveal the chiral magnetic ground state of portions of the unit cell that were not previously imaged with spin-polarized scanning tunneling microscopy alone. Using density functional theory, we investigate the structural and electronic properties of the reconstructed bilayer and identify the favorable stoichiometry regime in agreement with our experimental result.

An open source/real-time atomic force microscope architecture to perform customizable force spectroscopy experiments.

Science.gov (United States)

Materassi, Donatello; Baschieri, Paolo; Tiribilli, Bruno; Zuccheri, Giampaolo; Samorì, Bruno

2009-08-01

We describe the realization of an atomic force microscope architecture designed to perform customizable experiments in a flexible and automatic way. Novel technological contributions are given by the software implementation platform (RTAI-LINUX), which is free and open source, and from a functional point of view, by the implementation of hard real-time control algorithms. Some other technical solutions such as a new way to estimate the optical lever constant are described as well. The adoption of this architecture provides many degrees of freedom in the device behavior and, furthermore, allows one to obtain a flexible experimental instrument at a relatively low cost. In particular, we show how such a system has been employed to obtain measures in sophisticated single-molecule force spectroscopy experiments [Fernandez and Li, Science 303, 1674 (2004)]. Experimental results on proteins already studied using the same methodologies are provided in order to show the reliability of the measure system.

Ultratrace determination of tin by hydride generation in-atomizer trapping atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Průša, Libor [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Charles University in Prague, Faculty of Science, Department of Analytical Chemistry, Hlavova 8, Prague 2, CZ 128 43 Czech Republic (Czech Republic); Dědina, Jiří [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Kratzer, Jan, E-mail: jkratzer@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

2013-12-04

Graphical abstract: -- Highlights: •In-atomizer trapping HG-AAS was optimized for Sn. •A compact quartz trap-and-atomizer device was employed. •Generation, preconcentration and atomization steps were investigated in detail. •Hundred percent preconcentration efficiency for tin was reached. •Routine analytical method was developed for Sn determination (LOD of 0.03 ng mL{sup −1} Sn). -- Abstract: A quartz multiatomizer with its inlet arm modified to serve as a trap (trap-and-atomizer device) was employed to trap tin hydride and subsequently to volatilize collected analyte species with atomic absorption spectrometric detection. Generation, atomization and preconcentration conditions were optimized and analytical figures of merit of both on-line atomization as well as preconcentration modes were quantified. Preconcentration efficiency of 95 ± 5% was found. The detection limits reached were 0.029 and 0.14 ng mL{sup −1} Sn, respectively, for 120 s preconcentration period and on-line atomization mode without any preconcentration. The interference extent of other hydride forming elements (As, Se, Sb and Bi) on tin determination was found negligible in both modes of operation. The applicability of the developed preconcentration method was verified by Sn determination in a certified reference material as well as by analysis of real samples.

In situ single-atom array synthesis using dynamic holographic optical tweezers

Science.gov (United States)

Kim, Hyosub; Lee, Woojun; Lee, Han-gyeol; Jo, Hanlae; Song, Yunheung; Ahn, Jaewook

2016-01-01

Establishing a reliable method to form scalable neutral-atom platforms is an essential cornerstone for quantum computation, quantum simulation and quantum many-body physics. Here we demonstrate a real-time transport of single atoms using holographic microtraps controlled by a liquid-crystal spatial light modulator. For this, an analytical design approach to flicker-free microtrap movement is devised and cold rubidium atoms are simultaneously rearranged with 2N motional degrees of freedom, representing unprecedented space controllability. We also accomplish an in situ feedback control for single-atom rearrangements with the high success rate of 99% for up to 10 μm translation. We hope this proof-of-principle demonstration of high-fidelity atom-array preparations will be useful for deterministic loading of N single atoms, especially on arbitrary lattice locations, and also for real-time qubit shuttling in high-dimensional quantum computing architectures. PMID:27796372

Atomization of volatile compounds for atomic absorption and atomic fluorescence spectrometry: On the way towards the ideal atomizer

International Nuclear Information System (INIS)

Dedina, Jiri

2007-01-01

approach, trapping on quartz surfaces in an excess of oxygen with subsequent atomization in multiatomizer or in conventional quartz tubes, is very promising. It requires only simple and cheap equipment. The potential to reach very low detection limits is even better than for in-situ trapping in GF. However, it is a novel method which will have to be tested more extensively before it can considered to be a tool for routine analysis. Almost all the applications of AFS employ a miniature diffusion flame for the atomization. The alternative, the flame-in-gas-shield atomizer, is more complicated but it offers a substantially better signal to noise ratio. The current state-of-the-art of all individual atomizers, including advantages, drawbacks and perspectives, is recapitulated in detail. Also the most recent knowledge of the mechanism of processes taking place in the atomizers is treated

REAL-TIME OBJECT DETECTION IN PARALLEL THROUGH ATOMIC TRANSACTIONS

Directory of Open Access Journals (Sweden)

K Sivakumar

2016-11-01

Full Text Available Object detection and tracking is important operation involved in embedded systems like video surveillance, Traffic monitoring, campus security system, machine vision applications and other areas. Detecting and tracking multiple objects in a video or image is challenging problem in machine vision and computer vision based embedded systems. Implementation of such a object detection and tracking systems are done in sequential way of processing and also it was implemented using hardware synthesize tools like verilog HDL with FPGA, achieves considerably lesser performance in speed and it does support lesser atomic transactions. There are many object detection and tracking algorithm were proposed and implemented, among them background subtraction is one of them. This paper proposes a implementation of detecting and tracking multiple objects based on background subtraction algorithm using java and .NET and also discuss about the architecture concept for object detection through atomic transactional, modern hardware synthesizes language called Bluespec.

Evaluation of the roughness of the surface of porcelain systems with the atomic force microscope

International Nuclear Information System (INIS)

Chavarria Rodriguez, Bernal

2013-01-01

The surface of a dental ceramic was evaluated and compared with an atomic force microscope after being treated with different systems of polishing. 14 identical ceramic Lava® Zirconia discs were used to test the different polishing systems. 3 polishing systems from different matrix houses were used to polish dental porcelain. The samples were evaluated quantitatively with an atomic force microscope in order to study the real effectiveness of each system, on the roughness average (Ra) and the maximum peak to valley roughness (Ry) of the ceramic surfaces. A considerable reduction of the surface roughness was obtained by applying different polishing systems on the surface of dental ceramics. Very reliable values of Ra and Ry were obtained by making measurements on the structure reproduced by the atomic force microscope. The advanced ceramics of zirconium oxide presented the best physical characteristics and low levels of surface roughness. A smoother surface was achieved with the application of polishing systems, thus demonstrating the reduction of the surface roughness of a dental ceramic [es

The energy crisis and Bonn's atomic energy programme

International Nuclear Information System (INIS)

Steinhaus, K.; Heimbrecht, J.

1979-01-01

What are the background and causes of the energy crisis. In whose interest and on whose back is energy policy made in our country. Will the lights go out without nuclear power. Which are the real goals and dangers of Bonn's atomic energy programme. Is coal a real alternative to nuclear power in the Federal Republic of Germany. What possibilities and requirements are there for a national and democratic energy policy in the Federal Republic of Germany. Which are the central problems of the protest movement against the government's atomic energy programme. These questions, which are still in the centre of political discussion, are investigated by the authors. (orig.) [de

Atomic interferometry

International Nuclear Information System (INIS)

Baudon, J.; Robert, J.

2004-01-01

Since the theoretical works of L. De Broglie (1924) and the famous experiment of Davisson and Germer (1927), we know that a wave is linked with any particle of mass m by the relation λ = h/(mv), where λ is the wavelength, v the particle velocity and h is the Planck constant. The basic principle of the interferometry of any material particle, atom, molecule or aggregate is simple: using a simple incident wave, several mutually consistent waves (with well-defined relative phases) are generated and controllable phase-shifts are introduced between them in order to generate a wave which is the sum of the previous waves. An interference figure is obtained which consists in a succession of dark and bright fringes. The atomic interferometry is based on the same principle but involves different techniques, different wave equations, but also different beams, sources and correlations which are described in this book. Because of the small possible wavelengths and the wide range of possible atomic interactions, atomic interferometers can be used in many domains from the sub-micron lithography to the construction of sensors like: inertial sensors, gravity-meters, accelerometers, gyro-meters etc. The first chapter is a preliminary study of the space and time diffraction of atoms. The next chapters is devoted to the description of slit, light separation and polarization interferometers, and the last chapter treats of the properties of Bose-Einstein condensates which are interesting in atomic interferometry. (J.S.)

X-ray refractive index of laser-dressed atoms

OpenAIRE

Buth, Christian; Santra, Robin

2008-01-01

We investigated the complex index of refraction in the x-ray regime of atoms in laser light. The laser (intensity up to 10^13 W/cm^2, wavelength 800nm) modifies the atomic states but, by assumption, does not excite or ionize the atoms in their electronic ground state. Using quantum electrodynamics, we devise an ab initio theory to calculate the dynamic dipole polarizability and the photoabsorption cross section, which are subsequently used to determine the real and imaginary part, respectivel...

Quantum–classical correspondence in chaotic dynamics of laser-driven atoms

International Nuclear Information System (INIS)

Prants, S V

2017-01-01

This paper is a review article on some aspects of quantum–classical correspondence in chaotic dynamics of cold atoms interacting with a standing-wave laser field forming an optical lattice. The problem is treated from both (semi)classical and quantum points of view. In both approaches, the interaction of an atomic electic dipole with the laser field is treated quantum mechanically. Translational motion is described, at first, classically (atoms are considered to be point-like objects) and then quantum mechanically as a propagation of matter waves. Semiclassical equations of motion are shown to be chaotic in the sense of classical dynamical chaos. Point-like atoms in an absolutely deterministic and rigid optical lattice can move in a random-like manner demonstrating a chaotic walking with typical features of classical chaos. This behavior is explained by random-like ‘jumps’ of one of the atomic internal variable when atoms cross nodes of the standing wave and occurs in a specific range of the atom-field detuning. When treating atoms as matter waves, we show that they can make nonadiabatic transitions when crossing the standing-wave nodes. The point is that atomic wave packets split at each node in the same range of the atom-field detuning where the classical chaos occurs. The key point is that the squared amplitude of those semiclassical ‘jumps’ equal to the quantum Landau–Zener parameter which defines the probability of nonadiabatic transitions at the nodes. Nonadiabatic atomic wave packets are much more complicated compared to adiabatic ones and may be called chaotic in this sense. A few possible experiments to observe some manifestations of classical and quantum chaos with cold atoms in horizontal and vertical optical lattices are proposed and discussed. (paper)

Non-Hermitian optics in atomic systems

Science.gov (United States)

Zhang, Zhaoyang; Ma, Danmeng; Sheng, Jiteng; Zhang, Yiqi; Zhang, Yanpeng; Xiao, Min

2018-04-01

A wide class of non-Hermitian Hamiltonians can possess entirely real eigenvalues when they have parity-time (PT) symmetric potentials. Recently, this family of non-Hermitian systems has attracted considerable attention in diverse areas of physics due to their extraordinary properties, especially in optical systems based on solid-state materials, such as coupled gain-loss waveguides and microcavities. Considering the desired refractive index can be effectively manipulated through atomic coherence, it is important to realize such non-Hermitian optical potentials and further investigate their distinct properties in atomic systems. In this paper, we review the recent theoretical and experimental progress of non-Hermitian optics with coherently prepared multi-level atomic configurations. The realizations of (anti-) PT symmetry with different schemes have extensively demonstrated the special optical properties of non-Hermitian optical systems with atomic coherence.

Atomic physics of strongly correlated systems

International Nuclear Information System (INIS)

Lin, C.D.

1986-01-01

This abstract summarizes the progress made in the last year and the future plans of our research in the study of strongly correlated atomic systems. In atomic structure and atomic spectroscopy we are investigating the classification and supermultiplet structure of doubly excited states. We are also beginning the systematic study of triply excited states. In ion-atom collisions, we are exploring an AO-MO matching method for treating multi-electron collision systems to extract detailed information such as subshell cross sections, alignment and orientation parameters, etc. We are also beginning ab initio calculations on the angular distributions for electron transfer processes in low-energy (about 10-100eV/amu) ion-atom collisions in a full quantum mechanical treatment of the motion of heavy particles

Dependence of the Casimir-Polder interaction between an atom and a cavity wall on atomic and material properties

International Nuclear Information System (INIS)

Mostepanenko, V M; Babb, J F; Caride, A O; Klimchitskaya, G L; Zanette, S I

2006-01-01

The Casimir-Polder and van der Waals interactions between an atom and a flat cavity wall are investigated under the influence of real conditions including the dynamic polarizability of the atom, actual conductivity of the wall material and nonzero temperature of the wall. The cases of different atoms near metal and dielectric walls are considered. It is shown that to obtain accurate results for the atom-wall interaction at short separations, one should use the complete tabulated optical data for the complex refractive index of the wall material and the accurate dynamic polarizability of an atom. At relatively large separations in the case of a metal wall, one may use the plasma model dielectric function to describe the dielectric properties of the wall material. The obtained results are important for the theoretical interpretation of experiments on quantum reflection and Bose-Einstein condensation

Classical approach in atomic physics

International Nuclear Information System (INIS)

Solov'ev, E.A.

2011-01-01

The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of a hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom discovered with the help of Poincare section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treated as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormalization group symmetry, criterion of accuracy and so on are reviewed as well. (author)

Visualising reacting single atoms under controlled conditions: Advances in atomic resolution in situ Environmental (Scanning) Transmission Electron Microscopy (E(S)TEM)

Science.gov (United States)

Boyes, Edward D.; Gai, Pratibha L.

2014-02-01

Advances in atomic resolution Environmental (Scanning) Transmission Electron Microscopy (E(S)TEM) for probing gas-solid catalyst reactions in situ at the atomic level under controlled reaction conditions of gas environment and temperature are described. The recent development of the ESTEM extends the capability of the ETEM by providing the direct visualisation of single atoms and the atomic structure of selected solid state heterogeneous catalysts in their working states in real-time. Atomic resolution E(S)TEM provides a deeper understanding of the dynamic atomic processes at the surface of solids and their mechanisms of operation. The benefits of atomic resolution-E(S)TEM to science and technology include new knowledge leading to improved technological processes with substantial economic benefits, improved healthcare, reductions in energy needs and the management of environmental waste generation. xml:lang="fr"

Photoionization of atoms and molecules

International Nuclear Information System (INIS)

Samson, J.A.R.

1976-01-01

A literature review on the present state of knowledge in photoionization is presented. Various experimental techniques that have been developed to study photoionization, such as fluorescence and photoelectron spectroscopy, mass spectroscopy, are examined. Various atoms and molecules were chosen to illustrate these techniques, specifically helium and xenon atoms and hydrogen molecules. Specialized photoionization such as in positive and negative ions, excited states, and free radicals is also treated. Absorption cross sections and ionization potentials are also discussed

Preparation of Ultracold Atom Clouds at the Shot Noise Level

DEFF Research Database (Denmark)

Gajdacz, M.; Hilliard, A. J.; Kristensen, Mick

2016-01-01

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∼10^6 is determined by high precision Faraday imaging with uncertainty ΔN below the shot noise level, i.e., ΔN... 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....

Breakup of relativistic π+π- atoms in matter

International Nuclear Information System (INIS)

Afanasyev, L.G.; Tarasov, A.V.

1996-01-01

The relativistic motion of atoms formed by π+ and π- mesons in matter is considered. Exact analytic expressions for the form factors of hydrogenlike atoms for discrete-discrete transitions are obtained in a form convenient for numerical calculations. The total and transition cross sections for the interaction of π+π- atoms with matter are calculated in the Born approximation. The evolution of atomic-state populations is treated in terms of kinetic equations. The method of calculation makes it possible to obtain the populations of discrete atomic states, as well as the probability of transitions to the continuous spectrum (ionization). The proposed method yields the first experimental estimate of the lifetime of the π+π- atom

The real-world outcomes of treating Polycythemia Vera: Physician adherence to treatment guidelines.

Science.gov (United States)

Jackson Chornenki, Nicholas L; Chai-Adisaksopha, Chatree; Leong, Darryl P; Siegal, Deborah M; Hillis, Christopher M

2018-06-04

Therapy in Polycythemia Vera (PV), a myeloproliferative neoplasm, focuses on reducing cardiovascular (CV) risk without increasing bleeding or hematological progression. However, the real-world practice of treating PV in North America is understudied. We performed a retrospective cohort study of newly diagnosed PV (JAK2V617F mutation positive) patients in Hamilton, Canada to fill this knowledge gap. Out of 108 patients included, (n = 45, 41.7%) patients did not receive therapy consistent with contemporary treatment guidelines. Multivariable analysis showed increased white blood cell count at diagnosis (HR, 1.09; 95% CI, 1.04-1.14; p < 0.001), older age (HR, 1.15; 95% CI, 1.07-1.23; p < 0.001) and diabetic history (HR, 3.71; 95% CI, 1.27-10.78; p = 0.012) associated with greater mortality. Not receiving pharmacological treatment according to guidelines was also independently associated with increased mortality (HR, 3.12; 95% CI, 1.13-8.65; p = 0.029). Copyright © 2018 Elsevier Ltd. All rights reserved.

Drop-out rate among patients treated with omalizumab for severe asthma: Literature review and real-life experience.

Science.gov (United States)

Caminati, M; Senna, G; Stefanizzi, G; Bellamoli, R; Longhi, S; Chieco-Bianchi, F; Guarnieri, G; Tognella, S; Olivieri, M; Micheletto, C; Festi, G; Bertocco, E; Mazza, M; Rossi, A; Vianello, A

2016-08-25

In patients with asthma, particularly severe asthma, poor adherence to inhaled drugs negatively affects the achievement of disease control. A better adherence rate is expected in the case of injected drugs, such as omalizumab, as they are administered only in a hospital setting. However, adherence to omalizumab has never been systematically investigated. The aim of this study was to review the omalizumab drop-out rate in randomized controlled trials (RCTs) and real-life studies. A comparative analysis was performed between published data and the Italian North East Omalizumab Network (NEONet) database. In RCTs the drop-out rate ranged from 7.1 to 19.4 %. Although the reasons for withdrawal were only occasionally reported, patient decision and adverse events were the most frequently reported causes. In real-life studies the drop-out rate ranged from 0 to 45.5 %. In most cases lack of efficacy was responsible for treatment discontinuation. According to NEONet data, 32 % of treated patients dropped out, with an increasing number of drop outs observed over time. Patient decision and lack of efficacy accounted for most treatment withdrawals. Treatment adherence is particularly crucial in patients with severe asthma considering the clinical impact of the disease and the cost of non-adherence. The risk of treatment discontinuation has to be carefully considered both in the experimental and real-life settings. Increased knowledge regarding the main reasons for patient withdrawal is important to improve adherence in clinical practice.

Tunable-Range, Photon-Mediated Atomic Interactions in Multimode Cavity QED

Directory of Open Access Journals (Sweden)

Varun D. Vaidya

2018-01-01

Full Text Available Optical cavity QED provides a platform with which to explore quantum many-body physics in driven-dissipative systems. Single-mode cavities provide strong, infinite-range photon-mediated interactions among intracavity atoms. However, these global all-to-all couplings are limiting from the perspective of exploring quantum many-body physics beyond the mean-field approximation. The present work demonstrates that local couplings can be created using multimode cavity QED. This is established through measurements of the threshold of a superradiant, self-organization phase transition versus atomic position. Specifically, we experimentally show that the interference of near-degenerate cavity modes leads to both a strong and tunable-range interaction between Bose-Einstein condensates (BECs trapped within the cavity. We exploit the symmetry of a confocal cavity to measure the interaction between real BECs and their virtual images without unwanted contributions arising from the merger of real BECs. Atom-atom coupling may be tuned from short range to long range. This capability paves the way toward future explorations of exotic, strongly correlated systems such as quantum liquid crystals and driven-dissipative spin glasses.

The law for the Japan Atomic Energy Research Institute

International Nuclear Information System (INIS)

1985-01-01

The Act for Japan Atomic Energy Research Institute has been promulgated anew. Contents are the following : general rules, officials, advisors and personnel, duties, financial affairs and accounts, supervision, miscellaneous rules, penal provisions, and additional rules. (In the additional rules, the merger into JAERI of Japan Nuclear Ship Research and Development Agency is treated.) Japan Atomic Energy Research Institute conducts research etc. for the development of atomic energy comprehensively and efficiently, thereby contributing to the promotion of atomic energy research, development and utilization, according to the Atomic Energy Fundamental Act. Duties are atomic energy basic and application research, reactor relation, training of the personnel, RIs relation, etc. (Mori, K.)

Continuous measurement of an atomic current

Science.gov (United States)

Laflamme, C.; Yang, D.; Zoller, P.

2017-04-01

We are interested in dynamics of quantum many-body systems under continuous observation, and its physical realizations involving cold atoms in lattices. In the present work we focus on continuous measurement of atomic currents in lattice models, including the Hubbard model. We describe a Cavity QED setup, where measurement of a homodyne current provides a faithful representation of the atomic current as a function of time. We employ the quantum optical description in terms of a diffusive stochastic Schrödinger equation to follow the time evolution of the atomic system conditional to observing a given homodyne current trajectory, thus accounting for the competition between the Hamiltonian evolution and measurement back action. As an illustration, we discuss minimal models of atomic dynamics and continuous current measurement on rings with synthetic gauge fields, involving both real space and synthetic dimension lattices (represented by internal atomic states). Finally, by "not reading" the current measurements the time evolution of the atomic system is governed by a master equation, where—depending on the microscopic details of our CQED setups—we effectively engineer a current coupling of our system to a quantum reservoir. This provides interesting scenarios of dissipative dynamics generating "dark" pure quantum many-body states.

Holographic atom imaging from experimental photoelectron angular distribution patterns

International Nuclear Information System (INIS)

Terminello, L.J.; Lapiano-Smith, D.A.; Barton, J.J.; Shirley, D.A.

1993-11-01

One of the most challenging areas of materials research is the imaging of technologically relevant materials with microscopic and atomic-scale resolution. As part of the development of these methods, near-surface atoms in single crystals were imaged using core-level photoelectron holograms. The angle-dependent electron diffraction patterns that constitute an electron hologram were two-dimensionally transformed to create a three dimensional, real-space image of the neighboring scattering atoms. They have made use of a multiple-wavenumber, phased-summing method to improve the atom imaging capabilities of experimental photoelectron holography using the Cu(001) and Pt(111) prototype systems. These studies are performed to evaluate the potential of holographic atom imaging methods as structural probes of unknown materials

Direct observation of atoms on surfaces by scanning tunnelling microscopy

International Nuclear Information System (INIS)

Baldeschwieler, J.D.

1989-01-01

The scanning tunnelling microscope is a non-destructive means of achieving atomic level resolution of crystal surfaces in real space to elucidate surface structures, electronic properties and chemical composition. Scanning tunnelling microscope is a powerful, real space surface structure probe complementary to other techniques such as x-ray diffraction. 21 refs., 8 figs

An atomic model of the Big Bang

Science.gov (United States)

Lasukov, V. V.

2013-03-01

An atomic model of the Big Bang has been developed on the basis of quantum geometrodynamics with a nonzero Hamiltonian and on the concept of gravitation developed by Logunov asymptotically combined with the Gliner's idea of a material interpretation of the cosmological constant. The Lemaître primordial atom in superpace-time, whose spatial coordinate is the so-called scaling factor of the Logunov metric of the effective Riemann space, acts as the Big Bang model. The primordial atom in superspace-time corresponds to spatialtime structures(spheres, lines, and surfaces of a level) of the Minkowski spacetime real within the Logunov gravitation theory, the foregoing structures being filled with a scalar field with a negative density of potential energy.

Many electron effects in semiconductor quantum dots

Indian Academy of Sciences (India)

Semiconductor quantum dots (QDs) exhibit shell structures, very similar to atoms. Termed as 'artificial atoms' by some, they are much larger (1 100 nm) than real atoms. One can study a variety of manyelectron effects in them, which are otherwise difficult to observe in a real atom. We have treated these effects within the ...

An improved ultrafast 2D NMR experiment: Towards atom-resolved real-time studies of protein kinetics at multi-Hz rates

International Nuclear Information System (INIS)

Gal, Maayan; Kern, Thomas; Schanda, Paul; Frydman, Lucio; Brutscher, Bernhard

2009-01-01

Multidimensional NMR spectroscopy is a well-established technique for the characterization of structure and fast-time-scale dynamics of highly populated ground states of biological macromolecules. The investigation of short-lived excited states that are important for molecular folding, misfolding and function, however, remains a challenge for modern biomolecular NMR techniques. Off-equilibrium real-time kinetic NMR methods allow direct observation of conformational or chemical changes by following peak positions and intensities in a series of spectra recorded during a kinetic event. Because standard multidimensional NMR methods required to yield sufficient atom-resolution are intrinsically time-consuming, many interesting phenomena are excluded from real-time NMR analysis. Recently, spatially encoded ultrafast 2D NMR techniques have been proposed that allow one to acquire a 2D NMR experiment within a single transient. In addition, when combined with the SOFAST technique, such ultrafast experiments can be repeated at high rates. One of the problems detected for such ultrafast protein NMR experiments is related to the heteronuclear decoupling during detection with interferences between the pulses and the oscillatory magnetic field gradients arising in this scheme. Here we present a method for improved ultrafast data acquisition yielding higher signal to noise and sharper lines in single-scan 2D NMR spectra. In combination with a fast-mixing device, the recording of 1 H- 15 N correlation spectra with repetition rates of up to a few Hertz becomes feasible, enabling real-time studies of protein kinetics occurring on time scales down to a few seconds

Cold atoms in singular potentials

International Nuclear Information System (INIS)

Denschlag, J. P.

1998-09-01

We studied both theoretically and experimentally the interaction between cold Li atoms from a magnetic-optical trap (MOT) and a charged or current-carrying wire. With this system, we were able to realize 1/r 2 and 1/r potentials in two dimensions and to observe the motion of cold atoms in both potentials. For an atom in an attractive 1/r 2 potential, there exist no stable trajectories, instead there is a characteristic class of trajectories for which atoms fall into the singularity. We were able to observe this falling of atoms into the center of the potential. Moreover, by probing the singular 1/r 2 potential with atomic clouds of varying size and temperature we extracted scaling properties of the atom-wire interaction. For very cold atoms, and very thin wires the motion of the atoms must be treated quantum mechanically. Here we predict that the absorption cross section for the 1/r 2 potential should exhibit quantum steps. These quantum steps are a manifestation of the quantum mechanical decomposition of plane waves into partial waves. For the second part of this work, we realized a two dimensional 1/r potential for cold atoms. If the potential is attractive, the atoms can be bound and follow Kepler-like orbits around the wire. The motion in the third dimension along the wire is free. We were able to exploit this property and constructed a novel cold atom guide, the 'Kepler guide'. We also demonstrated another type of atom guide (the 'side guide'), by combining the magnetic field of the wire with a homogeneous offset magnetic field. In this case, the atoms are held in a potential 'tube' on the side of the wire. The versatility, simplicity, and scaling properties of this guide make it an interesting technique. (author)

Atomic politics

International Nuclear Information System (INIS)

Skogmar, G.

1979-01-01

The authors basic point is that the military and civil sides of atomic energy cannot be separated. The general aim of the book is to analyze both the military and civil branches, and the interdependence between them, of American foreign policy in the atomic field. Atomic policy is seen as one of the most important imstruments of foreign policy which, in turn, is seen against the background of American imperialism in general. Firstly, the book investigates the most important means by which the United States has controlled the development in the nuclear field in other countries. These means include influencing the conditions of access to nuclear resources of various kinds, influencing the flow of technical-economic information and influencing international organizations and treaties bearing on atomic energy. The time period treated is 1945-1973. 1973 is chosen as the end-year of the study mainly because of the new conditions in the whole energy field initiated by the oil crisis in that year. The sources of the empirical work are mainly hearings before the Joint Committee on Atomic Energy of the U.S. Congress and legal material of various kinds. Secondly, the goals of the American policy are analyzed. The goals identified are armament effect, non-proliferation (horizontal), sales, and energy dependence. The relation between the main goals is discussed.The discussion is centered on the interdependence between the military and the civil aspects, conflict and coincidence of various goals, the relation between short-term and long-term goals, and the possibilities of using one goal as pretext for another. Thirdly, some causes of the changes in the atomic policy around 1953 and 1963 are identified. These are the strategic balance, the competitive situation, the capacity (of the American atomic productive apparatus), and the nuclear technological stage. The specific composition of these four factors at the two time-points can explain the changes of policy. (author)

Inhibition and recovery of nitrification in treating real coal gasification wastewater with moving bed biofilm reactor

Institute of Scientific and Technical Information of China (English)

Huiqiang Li; Hongjun Han; Maoan Du; Wei Wang

2011-01-01

Moving bed biofilm reactor (MBBR) was used to treat real coal gasification wastewater.Nitrification of the MBBR was inhibited almost completely during start-up period.Sudden increase of influent total NH3 concentration was the main factor inducing nitrification inhibition.Increasing DO concentration in the bulk liquid (from 2 to 3 mg/L) had little effect on nitrification recovery.Nitrification of the MBBR recovered partially by the addition of nitrifying sludge into the reactor and almost ceased within 5 days.Nitrification ratio of the MBBR achieved 65％ within 12 days by increasing dilute ratio of the influent wastewater with tap water.The ratio of nitrification decreased to 25％ when infiuent COD concentration increased from 650 to 1000 mg/L after nitrification recovery and recovered 70％for another 4 days.

Evanescent light-wave atom mirrors, resonators, waveguides, and traps

International Nuclear Information System (INIS)

Dowling, J.P.; Gea-Banacloche, J.

1996-01-01

For many years, it has been known that light can be used to trap and manipulate small dielectric particles and atoms. In particular, the intense coherent light of lasers has been used to cool neutral atoms down to the micro-Kelvin and now even the nano-Kelvin regimes. At such low temperatures, the de Broglie wavelike character of the atoms becomes pronounced, making it necessary to treat the atoms as wave phenomena. To this end, the study of atom optics has recently developed, in which atom optical elements are fabricated in order to manipulate atoms, while utilizing and preserving the coherence and superposition properties inherent in their wavelike propagation. For example, there has been a concerted effort to study theoretically and produce experimentally the atom optic analogs of photonic optical elements, such as atom beam splitters, atom diffraction gratings, atom lenses, atom interferometers, and-last but not least-atom mirrors. It is light-induced atom mirrors, and their application to making atom resonators, waveguides, and traps, that we shall focus on in this chapter. 133 refs., 26 figs., 1 tab

Feedback control of atomic motion in an optical lattice

International Nuclear Information System (INIS)

Morrow, N.V.; Dutta, S.K.; Raithel, G.

2002-01-01

We demonstrate a real-time feedback scheme to manipulate wave-packet oscillations of atoms in an optical lattice. The average position of the atoms in the lattice wells is measured continuously and nondestructively. A feedback loop processes the position signal and translates the lattice potential. Depending on the feedback loop characteristics, we find amplification, damping, or an entire alteration of the wave-packet oscillations. Our results are well supported by simulations

The relativistic Scott correction for atoms and molecules

DEFF Research Database (Denmark)

Solovej, Jan Philip; Sørensen, Thomas Østergaard; Spitzer, Wolfgang L.

We prove the first correction to the leading Thomas-Fermi energy for the ground state energy of atoms and molecules in a model where the kinetic energy of the electrons is treated relativistically. The leading Thomas-Fermi energy, established in [25], as well as the correction given here are of s......We prove the first correction to the leading Thomas-Fermi energy for the ground state energy of atoms and molecules in a model where the kinetic energy of the electrons is treated relativistically. The leading Thomas-Fermi energy, established in [25], as well as the correction given here...... are of semi-classical nature. Our result on atoms and molecules is proved from a general semi-classical estimate for relativistic operators with potentials with Coulomb-like singularities. This semi-classical estimate is obtained using the coherent state calculus introduced in [36]. The paper contains...

Interaction of antiprotons with Rb atoms and a comparison of antiproton stopping powers of the atoms H, Li, Na, K, and Rb

DEFF Research Database (Denmark)

Lühr, Armin Christian; Fischer, Nicolas; Saenz, Alejandro

2009-01-01

Ionization and excitation cross sections as well as electron-energy spectra and stopping powers of the alkali metal atoms Li, Na, K, and Rb colliding with antiprotons were calculated using a time-dependent channel-coupling approach. An impact-energy range from 0.25 to 4000 keV was considered....... The target atoms are treated as effective one-electron systems using a model potential. The results are compared with calculated cross sections for antiproton-hydrogen atom collisions....

Status of the atomized uranium silicide fuel development at KAERI

Energy Technology Data Exchange (ETDEWEB)

Kim, C.K.; Kim, K.H.; Park, H.D.; Kuk, I.H. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1997-08-01

While developing KMRR fuel fabrication technology an atomizing technique has been applied in order to eliminate the difficulties relating to the tough property of U{sub 3}Si and to take advantage of the rapid solidification effect of atomization. The comparison between the conventionally comminuted powder dispersion fuel and the atomized powder dispersion fuel has been made. As the result, the processes, uranium silicide powdering and heat treatment for U{sub 3}Si transformation, become simplified. The workability, the thermal conductivity and the thermal compatibility of fuel meat have been investigated and found to be improved due to the spherical shape of atomized powder. In this presentation the overall developments of atomized U{sub 3}Si dispersion fuel and the planned activities for applying the atomizing technique to the real fuel fabrication are described.

STANDARD ATOMIC WEIGHT VALUES FOR THE MONONUCLIDIC ELEMENTS - 2001

International Nuclear Information System (INIS)

HOLDEN, N.E.

2001-01-01

Atomic Mass Evaluations have had a major impact on the values of the atomic weights for the twenty mononuclidic elements plus two elements, Thorium and Protactinium, which have no stable nuclides but a characteristic terrestrial isotopic composition. This paper reviews the history of the atomic weight values of these elements in the years, since the reference mass standard changed from 16 O to 12 C. There is a problem for Thorium, which is considered to have an abundance value of 100%, but is not treated as such in the Standard Atomic Weights' Table. Recommendations for handling the Standard Atomic Weight values for 2001 are presented

Dynamic of cold-atom tips in anharmonic potentials

Science.gov (United States)

Menold, Tobias; Federsel, Peter; Rogulj, Carola; Hölscher, Hendrik; Fortágh, József

2016-01-01

Background: Understanding the dynamics of ultracold quantum gases in an anharmonic potential is essential for applications in the new field of cold-atom scanning probe microscopy. Therein, cold atomic ensembles are used as sensitive probe tips to investigate nanostructured surfaces and surface-near potentials, which typically cause anharmonic tip motion. Results: Besides a theoretical description of this anharmonic tip motion, we introduce a novel method for detecting the cold-atom tip dynamics in situ and real time. In agreement with theory, the first measurements show that particle interactions and anharmonic motion have a significant impact on the tip dynamics. Conclusion: Our findings will be crucial for the realization of high-sensitivity force spectroscopy with cold-atom tips and could possibly allow for the development of advanced spectroscopic techniques such as Q-control. PMID:28144505

Low-energy scattering of excited helium atoms by rare gases

International Nuclear Information System (INIS)

Peach, G.

1978-01-01

The construction of semi-empirical model potentials for systems composed of helium in an excited state (Hestar) and a rare-gas atom (He or Ne) is described. The model of the atom-atom pair which has been adopted is one in which the excited electron is included explicitly, but the residual He + ion and the rare-gas atom are treated simply as cores which may be polarised. The results obtained are in satisfactory agreement with other calculations where they are available. (author)

Single-atom detection on a chip: from realization to application

Energy Technology Data Exchange (ETDEWEB)

Stibor, A; Bender, H; Kuehnhold, S; Fortagh, J; Zimmermann, C; Guenther, A, E-mail: aguenth@pit.physik.uni-tuebingen.d [CQ Center for Collective Quantum Phenomena and their Applications, Eberhard-Karls-Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

2010-06-15

In this paper, we describe the preparation and detection of ultracold atoms on a microchip with single-atom sensitivity. The detection scheme is based on multi-photon ionization of atoms and the subsequent guiding of the generated ions by ion optics to a channel electron multiplier. We resolve single atoms with a detection efficiency above 60%. The detector is suitable for real-time observations of static and dynamic processes in ultracold quantum gases. Although the ionization is destructive, sampling a small subset of the atomic distribution is sufficient for the determination of the desired information. We take full high-resolution spectra of ultracold atoms by ionizing only 5% of the atoms. Using an additional microwave near 6.8 GHz, the detection scheme becomes energy, position and state selective. This can be used for in situ determination of the energy distribution and temperature of atom clouds inside the trap and applied for future correlation measurements.

Information on the REAL84 exercise

International Nuclear Information System (INIS)

Zijp, W.L.; Cullen, D.E.

1986-01-01

This document gives information on the interlaboratory exercise REAL84. This exercise has as aim the improvement of the assessment of accuracies in radiation damage predictions by using good quality input data and proper calculation methods. In the exercise integral damage parameters (such as displacements per atom, or produced gas atoms) and spectrum characteristics are calculated for neutron spectra which are adjusted to fit experimental reaction rates obtained with activation spectrometry. The main difference with the preceding exercise REAL80 is that now improved information can be applied in the input data sets of the exercise. The improvement concerns mainly the availability of uncertainty information for the neutron spectrum and cross-section data. All parties interested are encouraged to participate in the exercise and to request from the IAEA the magnetic tape R84, which contains all input information. In order to meet the time schedule (see appendix) fast action is required. (author)

Investigation of potential genotoxic activity using the SOS Chromotest for real paracetamol wastewater and the wastewater treated by the Fenton process.

Science.gov (United States)

Kocak, Emel

2015-01-01

The potential genotoxic activity associated with high strength real paracetamol (PCT) wastewater (COD = 40,000 mg/L, TOC = 12,000 mg/L, BOD5 = 19,320 mg/L) from a large-scale drug-producing plant in the Marmara Region, was investigated in pre- and post- treated wastewater by the Fenton process (COD = 2,920 mg/L, TOC = 880 mg/L; BOD5 = 870 mg/L). The SOS Chromotest, which is based on Escherichia coli PQ37 activities, was used for the assessment of genotoxicity. The corrected induction factors (CIF) values used as quantitative measurements of the genotoxic activity were obtained from a total of four different dilutions (100, 50, 6.25, and 0.078 % v/v.) for two samples, in triplicate, to detect potentially genotoxic activities with the SOS Chromotest. The results of the SOS Chromotest demonstrated CIFmax value of 1.24, indicating that the PCT effluent (non-treated) is genotoxic. The results of the SOS Chromotest showed an CIFmax value of 1.72, indicating that the wastewater treated by Fenton process is genotoxic. The findings of this study clearly reveal that the PCT wastewater (non-treated) samples have a potentially hazardous impact on the aquatic environment before treatment, and in the wastewater that was treated by the Fenton process, genotoxicity generally increased.

Waves in periodic medium. Atomic matter waves in light crystals

International Nuclear Information System (INIS)

Oberthaler, M. K.

1997-07-01

This work deals with the propagation of matter waves inside a periodic potential. In analogy to photon optics a potential can be described by a refractive index for matter waves. A real potential leads to a refractive spatial structure while an imaginary potential leads to an absorptive structure. A general theoretical description is given in the framework of Floquet theory. The equivalent approach of dynamical diffraction theory will be treated in detail. The analytic solution for weak potentials are given in a general form so that they are applicable for every kind of wave and medium. For our experiments an open two level atom (metastable Argon) propagating inside a standing light wave was used. Detuning the frequency of the light wave from the atomic resonance leads to a real (refractive) periodic potential. Tuning the laser exact on resonance gives rise to a pure imaginary (absorptive) periodic potential. In analogy to solid state crystals in X-ray and neutron optics we call a standing light wave a light crystal. Tuning the standing light field on resonance we demonstrated experimentally the Borrmann effect. This effect describes the increase of the total transmission through a crystal for Bragg incidence. Furthermore, we confirmed that this effect is coherent and that a sinusoidal wave field is formed inside the crystal. The nodes of the wave field were found to coincide with the maxima of absorption. For a detuned standing light field a refractive crystal was realized, for which the expected Pendelloesung effect was demonstrated. In this case the maximum of the wave field inside the crystal was found at the steepest gradient of the potential as predicted by dynamical diffraction theory. Superposing an absorptive and a refractive light crystal a complex light crystal was realized. With such a crystal the violation of Friedel's law was demonstrated in a very clear way. (author)

The dispersion relation for the forward elastic electron-atom scattering amplitude

International Nuclear Information System (INIS)

Amusia, M.Y.

1978-01-01

The analytical properties of forward elastic electron-atom scattering amplitude are discussed. It is noted that the occurrence of exchange between the incoming and atomic electrons leads to the appearance of a number of singularities on the negative real axis in the complex energy plane. The conclusion is drawn that the dispersion relation for the forward electron-atom scattering amplitude should also include an integration over the negative energy from - I to - infinity, where I is the ionization potential. (author)

Dimensional perturbation theory for the two-electron atom

International Nuclear Information System (INIS)

Goodson, D.Z.

1987-01-01

Perturbation theory in δ = 1/D, where D is the dimensionality of space, is applied to the two-electron atom. In Chapter 1 an efficient procedure for calculating the coefficients of the perturbation series for the ground-state energy is developed using recursion relations between the moments of the coordinate operators. Results through tenth order are presented. The series is divergent, but Pade summation gives results comparable in accuracy to the best configuration-interaction calculations. The singularity structure of the Pade approximants confirms the hypothesis that the energy as a function of δ has an infinite sequence of poles on the negative real axis that approaches an essential singularity at δ = O. The essential singularity causes the divergence of the perturbation series. There are also two poles at δ = 1 that slow the asymptotic convergence of the low-order terms. In Chapter 2, various techniques are demonstrated for removing the effect of these poles, and accurate results are thereby obtained, even at very low order. In Chapter 3, the large D limit of the correlation energy (CE) is investigated. In the limit D → infinity it is only 35% smaller than at D = 3. It can be made to vanish in the limit by modifying the Hartree-Fock (HF) wavefunction. In Chapter 4, perturbation theory is applied to the Hooke's-law model of the atom. Prospects for treating more-complicated systems are briefly discussed

Principle and Reconstruction Algorithm for Atomic-Resolution Holography

Science.gov (United States)

Matsushita, Tomohiro; Muro, Takayuki; Matsui, Fumihiko; Happo, Naohisa; Hosokawa, Shinya; Ohoyama, Kenji; Sato-Tomita, Ayana; Sasaki, Yuji C.; Hayashi, Kouichi

2018-06-01

Atomic-resolution holography makes it possible to obtain the three-dimensional (3D) structure around a target atomic site. Translational symmetry of the atomic arrangement of the sample is not necessary, and the 3D atomic image can be measured when the local structure of the target atomic site is oriented. Therefore, 3D local atomic structures such as dopants and adsorbates are observable. Here, the atomic-resolution holography comprising photoelectron holography, X-ray fluorescence holography, neutron holography, and their inverse modes are treated. Although the measurement methods are different, they can be handled with a unified theory. The algorithm for reconstructing 3D atomic images from holograms plays an important role. Although Fourier transform-based methods have been proposed, they require the multiple-energy holograms. In addition, they cannot be directly applied to photoelectron holography because of the phase shift problem. We have developed methods based on the fitting method for reconstructing from single-energy and photoelectron holograms. The developed methods are applicable to all types of atomic-resolution holography.

Calcium Atom Trap for Atom Trap Mass Spectrometer

Energy Technology Data Exchange (ETDEWEB)

Ko, Kwang Hoon; Park, Hyun Min; Han, Jae Min; Kim, Taek Soo; Cha, Yong Ho; Lim, Gwon; Jeong, Do Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

Trace isotope analysis has been an important role in science, archaeological dating, geology, biology and nuclear industry. Artificially produced fission products such as Sr-90, Cs-135 and Kr-85 can be released to the environment when nuclear accident occurs and the reprocessing factory operates. Thus, the analysis of them has been of interest in nuclear industry. But it is difficult to detect them due to low natural abundance less then 10-10. The ultra-trace radio isotopes have been analyzed by the radio-chemical method, accelerator mass spectrometer, and laser based method. The radiochemical method has been used in the nuclear industry. But this method has disadvantages of long measurement time for long lived radioisotopes and toxic chemical process for the purification. The accelerator mass spectrometer has high isotope selectivity, but the system is huge and it has the isobar effects. The laser based method, such as RIMS (Resonance Ionization Mass Spectrometry) is a basically isobar-effect free method. Recently, ATTA (Atom Trap Trace Analysis), one of the laser based method, has been successfully demonstrated sufficient isotope selectivity with small system size. It has been applied for the detection of Kr-81 and Kr-85. However, it is not suitable for real sample detection, because it requires steady atomic beam generation during detection and is not allowed simultaneous detection of other isotopes. Therefore, we proposed the coupled method of Atom Trap and Mass Spectrometer. It consists of three parts, neutral atom trap, ionization and mass spectrometer. In this paper, we present the demonstration of the magneto-optical trap of neutral calcium. We discuss the isotope selective characteristics of the MOT (Magneto Optical Trap) of calcium by the fluorescence measurement. In addition, the frequency stabilization of the trap beam will be presented

Ultrafast atomic process in X-ray emission by using inner-shell ionization method for sodium and carbon atoms

Energy Technology Data Exchange (ETDEWEB)

Moribayashi, Kengo; Sasaki, Akira; Tajima, Toshiki [Japan Atomic Energy Research Inst., Neyagawa, Osaka (Japan). Kansai Research Establishment

1998-07-01

An ultrafast inner-shell ionization process with X-ray emission stimulated by high-intensity short-pulse X-ray is studied. Carbon and sodium atoms are treated as target matter. It is shown that atomic processes of the target determine the necessary X-ray intensity for X-ray laser emission as well as the features of X-ray laser such as wavelength and duration time. The intensity also depends on the density of initial atoms. Furthermore, we show that as the intensity of X-ray source becomes high, the multi-inner-shell ionization predominates, leading to the formation of hollow atoms. As the density of hollow atoms is increased by the pumping X-ray power, the emission of X-rays is not only of significance for high brightness X-ray measurement but also is good for X-ray lasing. New classes of experiments of pump X-ray probe and X-ray laser are suggested. (author)

NSTX-U Advances in Real-Time C++11 on Linux

Science.gov (United States)

Erickson, Keith G.

2015-08-01

Programming languages like C and Ada combined with proprietary embedded operating systems have dominated the real-time application space for decades. The new C++11 standard includes native, language-level support for concurrency, a required feature for any nontrivial event-oriented real-time software. Threads, Locks, and Atomics now exist to provide the necessary tools to build the structures that make up the foundation of a complex real-time system. The National Spherical Torus Experiment Upgrade (NSTX-U) at the Princeton Plasma Physics Laboratory (PPPL) is breaking new ground with the language as applied to the needs of fusion devices. A new Digital Coil Protection System (DCPS) will serve as the main protection mechanism for the magnetic coils, and it is written entirely in C++11 running on Concurrent Computer Corporation's real-time operating system, RedHawk Linux. It runs over 600 algorithms in a 5 kHz control loop that determine whether or not to shut down operations before physical damage occurs. To accomplish this, NSTX-U engineers developed software tools that do not currently exist elsewhere, including real-time atomic synchronization, real-time containers, and a real-time logging framework. Together with a recent (and carefully configured) version of the GCC compiler, these tools enable data acquisition, processing, and output using a conventional operating system to meet a hard real-time deadline (that is, missing one periodic is a failure) of 200 microseconds.

NSTX-U Advances in Real-Time C++11 on Linux

International Nuclear Information System (INIS)

Erickson, Keith G.

2015-01-01

Programming languages like C and Ada combined with proprietary embedded operating systems have dominated the real-time application space for decades. The new C++11standard includes native, language-level support for concurrency, a required feature for any nontrivial event-oriented real-time software. Threads, Locks, and Atomics now exist to provide the necessary tools to build the structures that make up the foundation of a complex real-time system. The National Spherical Torus Experiment Upgrade (NSTX-U) at the Princeton Plasma Physics Laboratory (PPPL) is breaking new ground with the language as applied to the needs of fusion devices. A new Digital Coil Protection System (DCPS) will serve as the main protection mechanism for the magnetic coils, and it is written entirely in C++11 running on Concurrent Computer Corporation's real-time operating system, RedHawk Linux. It runs over 600 algorithms in a 5 kHz control loop that determine whether or not to shut down operations before physical damage occurs. To accomplish this, NSTX-U engineers developed software tools that do not currently exist elsewhere, including real-time atomic synchronization, real-time containers, and a real-time logging framework. Together with a recent (and carefully configured) version of the GCC compiler, these tools enable data acquisition, processing, and output using a conventional operating system to meet a hard real-time deadline (that is, missing one periodic is a failure) of 200 microseconds

Ion-reversibility studies in amorphous solids using the two-atom scattering model

International Nuclear Information System (INIS)

Oen, O.S.

1981-06-01

An analytical two-atom scattering model has been developed to treat the recent discovery of the enhancement near 180 0 of Rutherford backscattering yields from disordered solids. In contrast to conventional calculations of Rutherford backscattering that treat scattering from a single atom only (the backscattering atom), the present model includes the interaction of a second atom lying between the target surface and the backscattering plane. The projectile ion makes a glancing collision with this second atom both before and after it is backscattered. The model predicts an enhancement effect whose physical origin arises from the tolerance of path for those ions whose inward and outward trajectories lie in the vicinity of the critical impact parameter. Results using Moliere scattering show how the yield enhancement depends on ion energy, backscattering depth, exit angle, scattering potential, atomic numbers of the projectile and target, and target density. In the model the critical impact parameter and critical angle play important roles. It is shown that these quantities depend on a single dimensionless parameter and analytical expressions for them are given which are accurate to better than 1%

Tunable atom-light beam splitter using electromagnetically induced transparency

Science.gov (United States)

Zhu, Xinyu; Wen, Rong; Chen, J. F.

2018-06-01

With electromagnetically induced transmission (EIT), an optical field can be converted into collective atomic excitation and stored in the atomic medium through switching off the strong-coupling field adiabatically. By varying the power of the coupling pulse, we can control the ratio between the transmitted optical field and the stored atomic mode. We use a cloud of cold 85Rb atoms prepared in magneto-optical trap as the experimental platform. Based on a model of EIT dark-state polariton, we consider the real case where the atomic medium has a finite length. The theoretical calculation gives numerical results that agree well with the experimental data. The results show that the ratio can be changed approximately from 0 to 100%, when the maximum power of the coupling pulse (the pulse length is 100 ns) varies from 0 to 20 mW, in the cold atomic ensemble with an optical depth of 40. This process can be used to achieve an atom-light hybrid beam splitter with tunable splitting ratio and thus find potential application in interferometric measurement and quantum information processing.

Resonance properties of a three-level atom with quantized field modes

International Nuclear Information System (INIS)

Yoo, H.I.

1984-01-01

A system of one three-level atom and one or two quantized electro-magnetic field modes coupled to each other by the dipole interaction, with the rotating wave approximation is studied. All three atomic configurations, i.e., cascade Lambda- and V-types, are treated simultaneously. The system is treated as closed, i.e., no interaction with the external radiation field modes, to reveal the internal structures and symmetries in the system. The general dynamics of the system are investigated under several distinct initial conditions and their similarities and differences with the dynamics of the Jaynes-Cummings model are revealed. Also investigated is the possibility of so-called coherent trapping of the atom in the quantized field modes in a resonator. An atomic state of coherent trapping exists only for limited cases, and it generally requires the field to be in some special states, depending on the system. The discussion of coherent trapping is extended into a system of M identical three-level atoms. The stability of a coherent-trapping state when fluorescence can take place is discussed. The distinction between a system with resonator field modes and one with ideal laser modes is made clear, and the atomic relaxation to the coherent-trapping atomic state when a Lambda-type atom is irradiated by two ideal laser beams is studied. The experimental prospects to observe the collapse-revival phenomena in the atomic occupation probabilities, which is characteristic of a system with quantized resonator field modes is discussed

[Real time diagnostics of instantaneous temperature of combustion and explosion process by modern spectroscopy].

Science.gov (United States)

Zhou, Xue-tie; Wang, Jun-de; Li, Yan; Liu, Da-bing

2003-04-01

The combustion temperature is one of the important parameters to express flame combustion and explosion characteristics. It will effectively guide the design and manufacture of new model explosives, industrial explosive materials, and weapons. The recent developments and applications of real time diagnostics of instantaneous temperature of combustion and explosion processes by modern spectroscopic methods, such as atomic absorption-emission method, atomic emission two-line spectroscopy, atomic emission multiline spectroscopy, molecular rotation-vibration spectroscopy, coherent anti-stokes Raman scattering (CARS) and plane laser-induced fluorescence (PLIF), were reviewed in this paper. The maximum time resolution of atomic absorption-emission method is 25 microseconds. The time resolution of atomic emission two-line spectroscopy can reach 0.1 microsecond. These two methods can completely suit the need of real time and instantaneous temperature diagnostics of violent explosion and flame combustion. Other methods will also provide new effective research methods for the processes and characteristics of combustion, flame and explosion.

Reaction kinetics of hydrogen atom abstraction from isopentanol by the H atom and HO2˙ radical.

Science.gov (United States)

Parab, Prajakta Rajaram; Heufer, K Alexander; Fernandes, Ravi Xavier

2018-04-25

Isopentanol is a potential next-generation biofuel for future applications to Homogeneous Charge Compression Ignition (HCCI) engine concepts. To provide insights into the combustion behavior of isopentanol, especially to its auto-ignition behavior which is linked both to efficiency and pollutant formation in real combustion systems, detailed quantum chemical studies for crucial reactions are desired. H-Abstraction reaction rates from fuel molecules are key initiation steps for chain branching required for auto-ignition. In this study, rate constants are determined for the hydrogen atom abstraction reactions from isopentanol by the H atom and HO2˙ radical by implementing the CBS-QB3 composite method. For the treatment of the internal rotors, a Pitzer-Gwinn-like approximation is applied. On comparing the computed reaction energies, the highest exothermicity (ΔE = -46 kJ mol-1) is depicted for Hα abstraction by the H atom whereas the lowest endothermicity (ΔE = 29 kJ mol-1) is shown for the abstraction of Hα by the HO2˙ radical. The formation of hydrogen bonding is found to affect the kinetics of the H atom abstraction reactions by the HO2˙ radical. Further above 750 K, the calculated high pressure limit rate constants indicate that the total contribution from delta carbon sites (Cδ) is predominant for hydrogen atom abstraction by the H atom and HO2˙ radical.

Atom-by-atom assembly

International Nuclear Information System (INIS)

Hla, Saw Wai

2014-01-01

Atomic manipulation using a scanning tunneling microscope (STM) tip enables the construction of quantum structures on an atom-by-atom basis, as well as the investigation of the electronic and dynamical properties of individual atoms on a one-atom-at-a-time basis. An STM is not only an instrument that is used to ‘see’ individual atoms by means of imaging, but is also a tool that is used to ‘touch’ and ‘take’ the atoms, or to ‘hear’ their movements. Therefore, the STM can be considered as the ‘eyes’, ‘hands’ and ‘ears’ of the scientists, connecting our macroscopic world to the exciting atomic world. In this article, various STM atom manipulation schemes and their example applications are described. The future directions of atomic level assembly on surfaces using scanning probe tips are also discussed. (review article)

Time evolution, Lamb shift, and emission spectra of spontaneous emission of two identical atoms

International Nuclear Information System (INIS)

Wang Dawei; Li Zhenghong; Zheng Hang; Zhu Shiyao

2010-01-01

A unitary transformation method is used to investigate the dynamic evolution of two multilevel atoms, in the basis of symmetric and antisymmetric states, with one atom being initially prepared in the first excited state and the other in the ground state. The unitary transformation guarantees that our calculations are based on the ground state of the atom-field system and the self-energy is subtracted at the beginning. The total Lamb shifts of the symmetric and antisymmetric states are divided into transformed shift and dynamic shift. The transformed shift is due to emitting and reabsorbing of virtual photons, by a single atom (nondynamic single atomic shift) and between the two atoms (quasi-static shift). The dynamic shift is due to the emitting and reabsorbing of real photons, by a single atom (dynamic single atomic shift) and between the two atoms (dynamic interatomic shift). The emitting and reabsorbing of virtual and real photons between the two atoms result in the interatomic shift, which does not exist for the one-atom case. The spectra at the long-time limit are calculated. If the distance between the two atoms is shorter than or comparable to the wavelength, the strong coupling between the two atoms splits the spectrum into two peaks, one from the symmetric state and the other from the antisymmetric state. The origin of the red or blue shifts for the symmetric and antisymmetric states mainly lies in the negative or positive interaction energy between the two atoms. In the investigation of the short time evolution, we find the modification of the effective density of states by the interaction between two atoms can modulate the quantum Zeno and quantum anti-Zeno effects in the decays of the symmetric and antisymmetric states.

Interaction of relativistic elementary atoms with matter. I. General formulas

International Nuclear Information System (INIS)

Mrowczyn'ski, S.

1987-01-01

The problem of the interaction of relativistic elementary atoms (Coulomb bound states of elementary particles such as positronium, pionium, etc.) with matter is studied in the reference frame where the atom is initially at rest. An atom of matter is treated as a spinless structureless fast particle. The amplitudes of elementary-atom interaction are derived in the Born approximation under the assumption that a momentum transfer to the atom does not significantly exceed an inverse Bohr radius of the atom. The elementary-atom excitation and ionization processes are considered. The transitions where the spin projection of the atom component is reversed are also studied. In particular the matrix elements for para-ortho and ortho-para transitions are given. The spin structure of the amplitudes is discussed in detail. The sum rules, which allow the calculation of the cross sections summed over atom final states are found. Finally the formulas of the atom interaction cross sections are presented

First results of the REAL-80 exercise

International Nuclear Information System (INIS)

Zijp, W.L.; Nolthenius, H.J.; Zsolnay, E.M.; Szondi, E.J.

1981-10-01

Some preliminary results are presented of the first phase of the interlaboratory exercise REAL80 to study uncertainties in integral parameters (such as displacement rate per atom steel, activation rate per atom nickel), derived from spectrum information obtained by means of activation spectrometry of well defined test cases. More balanced and extended results will be presented at the 4th ASTM-Euratom symposium on reactor dosimetry, Washington, D.C., 22-26 March 1982. In this first report attention has also been given to the nuclear data aspects of the exercise

Noncontact AFM Imaging of Atomic Defects on the Rutile TiO2 (110) Surface

DEFF Research Database (Denmark)

Lauritsen, Jeppe Vang

2015-01-01

The atomic force microscope (AFM) operated in the noncontact mode (nc-AFM) offers a unique tool for real space, atomic-scale characterisation of point defects and molecules on surfaces, irrespective of the substrate being electrically conducting or non-conducting. The nc-AFM has therefore in rece...

Limit on Excitation and Stabilization of Atoms in Intense Optical Laser Fields.

Science.gov (United States)

Zimmermann, H; Meise, S; Khujakulov, A; Magaña, A; Saenz, A; Eichmann, U

2018-03-23

Atomic excitation in strong optical laser fields has been found to take place even at intensities exceeding saturation. The concomitant acceleration of the atom in the focused laser field has been considered a strong link to, if not proof of, the existence of the so-called Kramers-Henneberger (KH) atom, a bound atomic system in an intense laser field. Recent findings have moved the importance of the KH atom from being purely of theoretical interest toward real world applications; for instance, in the context of laser filamentation. Considering this increasing importance, we explore the limits of strong-field excitation in optical fields, which are basically imposed by ionization through the spatial field envelope and the field propagation.

Momentum diffusion for coupled atom-cavity oscillators

International Nuclear Information System (INIS)

Murr, K.; Maunz, P.; Pinkse, P. W. H.; Puppe, T.; Schuster, I.; Rempe, G.; Vitali, D.

2006-01-01

It is shown that the momentum diffusion of free-space laser cooling has a natural correspondence in optical cavities when the internal state of the atom is treated as a harmonic oscillator. We derive a general expression for the momentum diffusion, which is valid for most configurations of interest: The atom or the cavity or both can be probed by lasers, with or without the presence of traps inducing local atomic frequency shifts. It is shown that, albeit the (possibly strong) coupling between atom and cavity, it is sufficient for deriving the momentum diffusion to consider that the atom couples to a mean cavity field, which gives a first contribution, and that the cavity mode couples to a mean atomic dipole, giving a second contribution. Both contributions have an intuitive form and present a clear symmetry. The total diffusion is the sum of these two contributions plus the diffusion originating from the fluctuations of the forces due to the coupling to the vacuum modes other than the cavity mode (the so-called spontaneous emission term). Examples are given that help to evaluate the heating rates induced by an optical cavity for experiments operating at low atomic saturation. We also point out intriguing situations where the atom is heated although it cannot scatter light

Sensitive detection of individual neutral atoms in a strong coupling cavity QED system

International Nuclear Information System (INIS)

Zhang Pengfei; Zhang Yuchi; Li Gang; Du Jinjin; Zhang Yanfeng; Guo Yanqiang; Wang Junmin; Zhang Tiancai; Li Weidong

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 magneto-optical 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 110 μs is obtained according to the probability distribution of the atom transits. (authors)

Analytic cross sections for collisions of H, H2, He and Li atoms and ions with atoms and molecules. 3

International Nuclear Information System (INIS)

Ito, Rinsuke; Tabata, Tatsuo; Shirai, Toshizo; Phaneuf, R.A.

1995-07-01

Analytic expressions fitted to Barnett's recommended data are given for the collision cross sections of H, H 2 , He, and Li atoms and ions colliding with atoms and molecules. The collisions treated are ionization collisions, charge-production collisions, electron-loss collisions, and electron detachment collisions. The analytic expressions use the semiempirical functional forms proposed by Green and McNeal and some modified forms to make it possible not only to interpolate but also to extrapolate the recommended data. (author)

Bose-Einstein condensation in real space

International Nuclear Information System (INIS)

Valencia, J.J.; Llano, M. de; Solis, M.A.

2004-01-01

We show how Bose-Einstein condensation (BEC) occurs not only in momentum space but also in coordinate (or real) space. Analogies between the isotherms of a van der Waals classical gas of extended (or finite-diameter) identical atoms and the point (or zero-diameter) particles of an ideal BE gas allow concluding that, in contrast with the classical case, the volume per particle vanishes in the pure BE condensate phase precisely because the boson diameters are zero. Thus a BE condensate forms in real space without exhibiting a liquid branch as does the classical gas. (Author)

Three-dimensional rearrangement of single atoms using actively controlled optical microtraps.

Science.gov (United States)

Lee, Woojun; Kim, Hyosub; Ahn, Jaewook

2016-05-02

We propose and demonstrate three-dimensional rearrangements of single atoms. In experiments performed with single 87Rb atoms in optical microtraps actively controlled by a spatial light modulator, we demonstrate various dynamic rearrangements of up to N = 9 atoms including rotation, 2D vacancy filling, guiding, compactification, and 3D shuffling. With the capability of a phase-only Fourier mask to generate arbitrary shapes of the holographic microtraps, it was possible to place single atoms at arbitrary geometries of a few μm size and even continuously reconfigure them by conveying each atom. For this purpose, we loaded a series of computer-generated phase masks in the full frame rate of 60 Hz of the spatial light modulator, so the animation of phase mask transformed the holographic microtraps in real time, driving each atom along the assigned trajectory. Possible applications of this method of transformation of single atoms include preparation of scalable quantum platforms for quantum computation, quantum simulation, and quantum many-body physics.

Fragmentation of atomic systems

International Nuclear Information System (INIS)

Bohn, J.L.; Fano, U.

1996-01-01

We report recent progress toward a nonperturbative formulation of many-body quantum dynamics that treats all constituent particles on an equal footing. This formulation is capable of detailing the evolution of a system toward the diverse fragments into which it can break up. We illustrate the general concept with the simple example of the simultaneous excitation of both electrons in a helium atom. copyright 1996 The American Physical Society

Real-time Detection of Antihydrogen Annihilations and Applications to Spectroscopy

Directory of Open Access Journals (Sweden)

Stracka Simone

2014-04-01

Full Text Available A detection scheme based on real-time measurement of antihydrogen annihilations during radiation injection is presented, which allows an efficient use of the trapped atoms for laser and microwave spectroscopy. The application of real-time detection of H¯$\\bar H$ annihilations to microwave spectroscopy, which yielded the first evidence of microwave induced spin-flip transitions in trapped antihydrogen [1], is reported.

Design Specifications for Adaptive Real-Time Systems

Science.gov (United States)

1991-12-01

TICfl \\ E CT E Design Specifications for JAN’\\ 1992 Adaptive Real - Time Systems fl Randall W. Lichota U, Alice H. Muntz - December 1991 \\ \\\\/ 0 / r...268-2056 Technical Report CMU/SEI-91-TR-20 ESD-91-TR-20 December 1991 Design Specifications for Adaptive Real - Time Systems Randall W. Lichota Hughes...Design Specifications for Adaptive Real - Time Systems Abstract: The design specification method described in this report treats a software

Small-polaron model of light atom diffusion

International Nuclear Information System (INIS)

Emin, D.

1977-01-01

A number of researchers have treated the diffusion of light interstitials in metals in strict analogy with the theory for the hopping diffusion of electrons in low-mobility insulators. In other words, these authors view the diffusion of light atoms as simply being an example of small-polaron hopping motion. In this paper the motion of a small polaron is introduced, and the mechanism of its motion is described. The experimental results are then succinctly presented. Next the physical assumptions implicit in the theory are compared with the situation which is believed to characterize the existence and motion of light interstitial atoms in metals. Concomitantly, the modifications of the small-polaron theory required in applying it to light atom diffusion are ennumerated

The atomic nucleus as a target

International Nuclear Information System (INIS)

Strugalski, Z.; Pawlak, T.

1981-01-01

The purpose of this article is to characterize the atomic nucleus used as a target in hadron-nucleus collision experiments. The atomic nucleus can be treated as a lens-shaped ''slab'' of nuclear matter. Such ''slab'' should be characterized by the nuclear matter layer thickness at any impact parameter, by its average thickness, and by its maximal thickness. Parameters characterizing atomic nuclei as targets are given for the elements: 6 12 C, 7 14 N, 8 16 O, 9 19 F, 10 20 Ne, 13 27 Al, 14 28 Si, 16 32 S, 18 40 Ar, 24 52 Cr, 26 54 Fe, 27 59 Co, 29 64 Cu, 30 65 Zn, 32 73 Ge, 35 80 Br, 47 100 Ag, 53 127 I, 54 131 Xe, 73 181 Ta, 74 184 W, 79 197 Au, 82 207 Pb, 92 -- 238 U [ru

Resolving amorphous solid-liquid interfaces by atomic force microscopy

International Nuclear Information System (INIS)

Burson, Kristen M.; Gura, Leonard; Kell, Burkhard; Büchner, Christin; Lewandowski, Adrian L.; Heyde, Markus; Freund, Hans-Joachim

2016-01-01

Recent advancements in liquid atomic force microscopy make it an ideal technique for probing the structure of solid-liquid interfaces. Here, we present a structural study of a two-dimensional amorphous silica bilayer immersed in an aqueous solution utilizing liquid atomic force microscopy with sub-nanometer resolution. Structures show good agreement with atomically resolved ultra-high vacuum scanning tunneling microscopy images obtained on the same sample system, owing to the structural stability of the silica bilayer and the imaging clarity from the two-dimensional sample system. Pair distance histograms of ring center positions are utilized to develop quantitative metrics for structural comparison, and the physical origin of pair distance histogram peaks is addressed by direct assessment of real space structures.

Internal Spin Control, Squeezing and Decoherence in Ensembles of Alkali Atomic Spins

Science.gov (United States)

Norris, Leigh Morgan

Large atomic ensembles interacting with light are one of the most promising platforms for quantum information processing. In the past decade, novel applications for these systems have emerged in quantum communication, quantum computing, and metrology. Essential to all of these applications is the controllability of the atomic ensemble, which is facilitated by a strong coupling between the atoms and light. Non-classical spin squeezed states are a crucial step in attaining greater ensemble control. The degree of entanglement present in these states, furthermore, serves as a benchmark for the strength of the atom-light interaction. Outside the broader context of quantum information processing with atomic ensembles, spin squeezed states have applications in metrology, where their quantum correlations can be harnessed to improve the precision of magnetometers and atomic clocks. This dissertation focuses upon the production of spin squeezed states in large ensembles of cold trapped alkali atoms interacting with optical fields. While most treatments of spin squeezing consider only the case in which the ensemble is composed of two level systems or qubits, we utilize the entire ground manifold of an alkali atom with hyperfine spin f greater than or equal to 1/2, a qudit. Spin squeezing requires non-classical correlations between the constituent atomic spins, which are generated through the atoms' collective coupling to the light. Either through measurement or multiple interactions with the atoms, the light mediates an entangling interaction that produces quantum correlations. Because the spin squeezing treated in this dissertation ultimately originates from the coupling between the light and atoms, conventional approaches of improving this squeezing have focused on increasing the optical density of the ensemble. The greater number of internal degrees of freedom and the controllability of the spin-f ground hyperfine manifold enable novel methods of enhancing squeezing. In

Atom chips in the real world: the effects of wire corrugation

OpenAIRE

Schumm , Thorsten; Estève , Jérôme; Aussibal , Christine; Figl , Cristina; Trebbia , Jean-Baptiste; Nguyen , Hai; Mailly , Dominique; Bouchoule , Isabelle; Westbrook , Christoph I; Aspect , Alain

2005-01-01

International audience; We present a detailed model describing the effects of wire corrugation on the trapping potential experienced by a cloud of atoms above a current carrying micro wire. We calculate the distortion of the current distribution due to corrugation and then derive the corresponding roughness in the magnetic field above the wire. Scaling laws are derived for the roughness as a function of height above a ribbon shaped wire. We also present experimental data on micro wire traps u...

Petos-Basic programs for treating data and reporting results in atomic spectroscopy

International Nuclear Information System (INIS)

Roca, M.

1985-01-01

A Petos-Basic program was written which provides the off-line treatment of data in optical emission spectroscopy, flame photometry and atomic absorption spectroscopy. Polynomial calibration functions are fitted in overlapped steps by the leastsquares method. The calculated concentrations in unknown samples are stored in sequential files (one per element, up to four), from which they can be read to be reported in a second program. (author)

Localized atomic basis set in the projector augmented wave method

DEFF Research Database (Denmark)

Larsen, Ask Hjorth; Vanin, Marco; Mortensen, Jens Jørgen

2009-01-01

We present an implementation of localized atomic-orbital basis sets in the projector augmented wave (PAW) formalism within the density-functional theory. The implementation in the real-space GPAW code provides a complementary basis set to the accurate but computationally more demanding grid...

Atom-surface potentials and atom interferometry

International Nuclear Information System (INIS)

Babb, J.F.

1998-01-01

Long-range atom-surface potentials characterize the physics of many actual systems and are now measurable spectroscopically in deflection of atomic beams in cavities or in reflection of atoms in atomic fountains. For a ground state, spherically symmetric atom the potential varies as -1/R 3 near the wall, where R is the atom-surface distance. For asymptotically large distances the potential is weaker and goes as -1/R 4 due to retardation arising from the finite speed of light. This diminished interaction can also be interpreted as a Casimir effect. The possibility of measuring atom-surface potentials using atomic interferometry is explored. The particular cases studied are the interactions of a ground-state alkali-metal atom and a dielectric or a conducting wall. Accurate descriptions of atom-surface potentials in theories of evanescent-wave atomic mirrors and evanescent wave-guided atoms are also discussed. (author)

Bremsstrahlung in atom-atom collisions

International Nuclear Information System (INIS)

Amus'ya, M.Y.; Kuchiev, M.Y.; Solov'ev, A.V.

1985-01-01

It is shown that in the collision of a fast atom with a target atom when the frequencies are on the order of the potentials or higher, there arises bremsstrahlung comparable in intensity with the bremsstrahlung emitted by an electron with the same velocity in the field of the target atom. The mechanism by which bremsstrahlung is produced in atom-atom collisions is elucidated. Results of specific calculations of the bremsstrahlung spectra are given for α particles and helium atoms colliding with xenon

Atomizing industrial gas-liquid flows – Development of an efficient hybrid VOF-LPT numerical framework

International Nuclear Information System (INIS)

Ström, Henrik; Sasic, Srdjan; Holm-Christensen, Olav; Shah, Louise Jivan

2016-01-01

Highlights: • Modelling of turbulent atomizing gas-liquid flows in real industrial devices. • A combined VOF-LPT framework with statistical coupling. • Regions of separated and dispersed multiphase flow treated simultaneously. • Statistical model based on a limited amount of highly resolved VOF data. - Abstract: Atomizing gas-liquid flows are used in industrial applications where high interphase heat and mass transfer rates and good mixing are of primary importance. Today, there is no single mathematical framework available to predict the entire liquid breakup process at an acceptable computational cost for a typical problem of industrial size. In this work, we develop a volume-of-fluid (VOF) framework that is combined with Lagrangian particle tracking (LPT) to take advantage of the respective strengths of these two approaches. The two frameworks are coupled via a statistical model that enables a transition from the VOF to the LPT formulation using input data about the primary breakup process obtained from detailed VOF simulations in dedicated switching zones. LPT-to-VOF transitions are handled directly by analyzing the proximity of LPT parcels to larger VOF structures. The combined framework is specifically designed to accommodate situations where atomization occurs in several locations simultaneously and when separated and dispersed turbulent gas-liquid flows co-exist in the same industrial unit. The procedure in which the statistical model is derived is presented and discussed, its performance is verified and the computational efficiency of the combined VOF-LPT model is assessed. Finally, the application of the coupled framework to the simulation of an industrial gas-liquid mixer with four separate atomization regions is presented.

Electronic and atomic impacts on large clusters

International Nuclear Information System (INIS)

Gspann, J.

1982-01-01

Describing first the generation and properties of molecular beams of large Van der Waals clusters such as speed distribution, cluster size distribution, and internal temperature of the clusters, the review then features the results of electronic impacts on large clusters: metastable electronic cluster excitations, ejection of positive cluster ions of less than 100 atoms from much larger parent clusters, and ionization of the large clusters. Atomic impacts at thermal energies are treated with respect to the scattering cross section of the clusters, their drag coefficient in free molecular flow, and the peculiarities of impacts on helium clusters of either isotope. (Auth.)

PETOS-BASIC programs for treating data and reporting results in atomic spectroscopy

International Nuclear Information System (INIS)

Roca, M.

1985-01-01

A PETOS-BASIC program was written which provides the off-line treatment of data in optical emission spectroscopy, flame photometry and, atomic absorption spectroscopy. Polynomial calibration functions are fitted in overlapped steps by the least squares method. The calculated concentrations in unknown samples are stored in sequential files (one per element, up to four), from which they can be read to be reported in a second program. (Author) 7 refs

Nuclear energy: the real costs; and reply

International Nuclear Information System (INIS)

Jeffery, J.W.; Jones, P.M.S.

1982-01-01

Comments are made on a review by Jones (Atom. 306 April 1982) of 'Nuclear Energy: the Real Costs' - a special report by the Committee for the Study of the Economics of Nuclear Electricity, and criticisms contained in the review of the analysis of nuclear costs presented in the report are discussed. Dr Jones replies. (U.K.)

Detecting an atomic clock frequency anomaly using an adaptive Kalman filter algorithm

Science.gov (United States)

Song, Huijie; Dong, Shaowu; Wu, Wenjun; Jiang, Meng; Wang, Weixiong

2018-06-01

The abnormal frequencies of an atomic clock mainly include frequency jump and frequency drift jump. Atomic clock frequency anomaly detection is a key technique in time-keeping. The Kalman filter algorithm, as a linear optimal algorithm, has been widely used in real-time detection for abnormal frequency. In order to obtain an optimal state estimation, the observation model and dynamic model of the Kalman filter algorithm should satisfy Gaussian white noise conditions. The detection performance is degraded if anomalies affect the observation model or dynamic model. The idea of the adaptive Kalman filter algorithm, applied to clock frequency anomaly detection, uses the residuals given by the prediction for building ‘an adaptive factor’ the prediction state covariance matrix is real-time corrected by the adaptive factor. The results show that the model error is reduced and the detection performance is improved. The effectiveness of the algorithm is verified by the frequency jump simulation, the frequency drift jump simulation and the measured data of the atomic clock by using the chi-square test.

The Tunneling Microscope: A New Look at the Atomic World.

Science.gov (United States)

Golovchenko, J. A.

1986-01-01

A new instrument called the tunneling microscope has recently been developed that is capable of generating real-space images of surfaces showing atomic structure. Discusses current capabilities, limitations, and the physics involved in the technique. Includes results from a study of silicon crystal surfaces. (JN)

A novel spacetime concept for describing electronic motion within a helium atom

OpenAIRE

Xu, Kunming

2007-01-01

Euclidean space and linear algebra do not characterize dynamic electronic orbitals satisfactorily for even the motion of both electrons in an inert helium atom cannot be defined in reasonable details. Here the author puts forward a novel two-dimensional spacetime model from scratch in the context of defining both electrons in a helium atom. Space and time are treated as two orthogonal, symmetric and complementary quantities under the atomic spacetime. Electronic motion observed the rule of di...

Quantum ratchets for periodically kicked cold atoms and Bose-Einstein condensates

Energy Technology Data Exchange (ETDEWEB)

Casati, Giulio [Center for Nonlinear and Complex Systems, Universita degli Studi dell' Insubria and Istituto Nazionale per la Fisica della Materia, Unita di Como, Via Valleggio 11, 22100 Como (Italy); Poletti, Dario [Center for Nonlinear and Complex Systems, Universita degli Studi dell' Insubria and Istituto Nazionale per la Fisica della Materia, Unita di Como, Via Valleggio 11, 22100 Como (Italy)

2007-05-15

We study cold atoms and Bose-Einstein condensates exposed to time-dependent standing waves of light. We first discuss a quantum chaotic dissipative ratchet using the method of quantum trajectories. This system is characterized by directed transport emerging from a quantum strange attractor. We then present a very simple model of directed transport with cold atoms in a pair of periodically flashed optical lattices. Finally we study the dynamics of a dilute Bose-Einstein condensate confined in a toroidal trap and exposed to a pair of periodically flashed optical lattices. We show that the many-body atom-atom interactions, treated within the mean-field approximation, can generate directed transport.

Inelastic collisions between an atom and a diatomic molecule. I. Theoretical and numerical considerations for the close coupling approximation

International Nuclear Information System (INIS)

Choi, B.H.; Tang, K.T.

1975-01-01

The close coupled differential equations for rotational excitation in collisions between an atom and a diatomic molecule are reformulated. Although it is equivalent to other formulations, it is computationally more convenient and gives a simpler expression for differential cross sections. Questions concerning real boundary conditions and the unitarity of the S matrix are discussed. Stormer's algorithm for solving coupled differential equations is introduced for molecular scatterings. This numerical procedure, which is known to be very useful in nuclear scattering problems, has to be modified for molecular systems. It is capable of treating the case where all channels are open as well as the case where some of the channels are closed. This algorithm is compared with other typical procedures of solving coupled differential equations

Quasiparticles in Raman scattering of an electromagnetic wave by an atomic condensate

International Nuclear Information System (INIS)

Il’ichev, L. V.

2011-01-01

Raman scattering of an intense electromagnetic wave by a free atomic Bose condensate is considered. In a system of atoms and photons, a subsystem is separated whose dynamics can be naturally described in terms of quasiparticles: quasi-atoms and quasi-photons. The dispersion laws of quasiparticles are interrupted by the instability interval. The introduction of quasiparticles within this interval is impossible, while dispersion laws that are continued formally acquire imaginary components. The dynamic scattering model is generalized by including dissipative annihilation processes of scattered photons and uncondensed atoms. A stationary solution of the corresponding quantum control equation is found, allowing the calculation of momentum distributions of real particles and quasiparticles. The outlook for the experimental detection of quasiparticles is discussed.

The relativistic Scott correction for atoms and molecules

DEFF Research Database (Denmark)

Solovej, Jan Philip; Sørensen, Thomas Østergaard; Spitzer, Wolfgang L.

2010-01-01

We prove the first correction to the leading Thomas-Fermi energy for the ground state energy of atoms and molecules in a model where the kinetic energy of the electrons is treated relativistically. The leading Thomas-Fermi energy, established in [25], as well as the correction given here......, are of semiclassical nature. Our result on atoms and molecules is proved from a general semiclassical estimate for relativistic operators with potentials with Coulomb-like singularities. This semiclassical estimate is obtained using the coherent state calculus introduced in [36]. The paper contains a unified treatment...

First-principles dynamics treatment of light emission in collisions between alkali-metal atom and noble-gas atom collisions at 10keV

Science.gov (United States)

Pacheco, Alexander B.; Reyes, Andrés; Micha, David A.

2006-12-01

Collision-induced light emission during the interaction of an alkali-metal atom and a noble-gas atom is treated within a first-principles, or direct, dynamics approach that calculates a time-dependent electric dipole for the whole system, and spectral emission cross sections from its Fourier transform. These cross sections are very sensitive to excited diatomic potentials and a source of information on their shape. The coupling between electronic transitions and nuclear motions is treated with atomic pseudopotentials and an electronic density matrix coupled to trajectories for the nuclei. A recently implemented pseudopotential parametrization scheme is used here for the ground and excited states of the LiHe system, and to calculate state-to-state dipole moments. To verify the accuracy of our new parameters, we recalculate the integral cross sections for the LiHe system in the keV energy regime and obtain agreement with other results from theory and experiment. We further present results for the emission spectrum from 10keV Li(2s)+He collisions, and compare them to experimental values available in the region of light emitted at 300-900nm .

Hydrogen atom in a magnetic field: Ghost orbits, catastrophes, and uniform semiclassical approximations

International Nuclear Information System (INIS)

Main, J.; Wunner, G.

1997-01-01

Applying closed-orbit theory to the recurrence spectra of the hydrogen atom in a magnetic field, one can interpret most, but not all, structures semiclassically in terms of closed classical orbits. In particular, conventional closed-orbit theory fails near bifurcations of orbits where semiclassical amplitudes exhibit unphysical divergences. Here we analyze the role of ghost orbits living in complex phase space. The ghosts can explain resonance structures in the spectra of the hydrogen atom in a magnetic field at positions where no real orbits exist. For three different types of catastrophes, viz. fold, cusp, and butterfly catastrophes, we construct uniform semiclassical approximations and demonstrate that these solutions are completely determined by classical parameters of the real orbits and complex ghosts. copyright 1997 The American Physical Society

Atomic Basic Blocks

Science.gov (United States)

Scheler, Fabian; Mitzlaff, Martin; Schröder-Preikschat, Wolfgang

Die Entscheidung, einen zeit- bzw. ereignisgesteuerten Ansatz für ein Echtzeitsystem zu verwenden, ist schwierig und sehr weitreichend. Weitreichend vor allem deshalb, weil diese beiden Ansätze mit äußerst unterschiedlichen Kontrollflussabstraktionen verknüpft sind, die eine spätere Migration zum anderen Paradigma sehr schwer oder gar unmöglich machen. Wir schlagen daher die Verwendung einer Zwischendarstellung vor, die unabhängig von der jeweils verwendeten Kontrollflussabstraktion ist. Für diesen Zweck verwenden wir auf Basisblöcken basierende Atomic Basic Blocks (ABB) und bauen darauf ein Werkzeug, den Real-Time Systems Compiler (RTSC) auf, der die Migration zwischen zeit- und ereignisgesteuerten Systemen unterstützt.

In-situ environmental (scanning) transmission electron microscopy of catalysts at the atomic level

International Nuclear Information System (INIS)

Gai, P L; Boyes, E D

2014-01-01

Observing reacting single atoms on the solid catalyst surfaces under controlled reaction conditions is a key goal in understanding and controlling heterogeneous catalytic reactions. In-situ real time aberration corrected environmental (scanning) transmission electron microscopy (E(S)TEM permit the direct imaging of dynamic surface and sub-surface structures of reacting catalysts. In this paper in-situ AC ETEM and AC ESTEM studies under controlled reaction environments of oxide catalysts and supported metal nanocatalysts important in chemical industry are presented. They provide the direct evidence of dynamic processes at the oxide catalyst surface at the atomic scale and single atom dynamics in catalytic reactions. The ESTEM studies of single atom dynamics in controlled reaction environments show that nanoparticles act as reservoirs of ad-atoms. The results have important implications in catalysis and nanoparticle studies

Laser-assisted atom-atom collisions

International Nuclear Information System (INIS)

Roussel, F.

1984-01-01

The basic layer-assisted atom-atom collision processes are reviewed in order to get a simpler picture of the main physical facts. The processes can be separated into two groups: optical collisions where only one atom is changing state during the collision, the other acting as a spectator atom, and radiative collisions where the states of the two atoms are changing during the collision. All the processes can be interpreted in terms of photoexcitation of the quasimolecule formed during the collisional process. (author)

The most negative ion in the Thomas-Fermi-von Weizsaecker theory of atoms and molecules

International Nuclear Information System (INIS)

Benguria, R.; Lieb, E.H.; Princeton Univ., NJ

1985-01-01

Let Nsub(c) denote the maximum number of electrons that can be bound to an atom of nuclear charge z, in the Thomas-Fermi-von Weizaecker theory. It is proved that Nsub(c) cannot exceed z by more than one, and thus this theory is in agreement with experimental facts about real atoms. A similar result is proved for molecules, i.e. Nsub(c) cannot exceed the total nuclear charge by more than the number of atoms in the molecule. (author)

Fine structures of atomic excited states: precision atomic spectroscopy and electron-ion collision process

International Nuclear Information System (INIS)

Gao Xiang; Cheng Cheng; Li Jiaming

2011-01-01

Scientific research fields for future energies such as inertial confinement fusion researches and astrophysics studies especially with satellite observatories advance into stages of precision physics. The relevant atomic data are not only enormous but also of accuracy according to requirements, especially for both energy levels and the collision data. The fine structure of high excited states of atoms and ions can be measured by precision spectroscopy. Such precision measurements can provide not only knowledge about detailed dynamics of electron-ion interactions but also a bench mark examination of the accuracy of electron-ion collision data, especially incorporating theoretical computations. We illustrate that by using theoretical calculation methods which can treat the bound states and the adjacent continua on equal footing. The precision spectroscopic measurements of excited fine structures can be served as stringent tests of electron-ion collision data. (authors)

Surface structure investigations using noncontact atomic force microscopy

International Nuclear Information System (INIS)

Kolodziej, J.J.; Such, B.; Goryl, M.; Krok, F.; Piatkowski, P.; Szymonski, M.

2006-01-01

Surfaces of several A III B V compound semiconductors (InSb, GaAs, InP, InAs) of the (0 0 1) orientation have been studied with noncontact atomic force microscopy (NC-AFM). Obtained atomically resolved patterns have been compared with structural models available in the literature. It is shown that NC-AFM is an efficient tool for imaging complex surface structures in real space. It is also demonstrated that the recent structural models of III-V compound surfaces provide a sound base for interpretation of majority of features present in recorded patterns. However, there are also many new findings revealed by the NC-AFM method that is still new experimental technique in the context of surface structure determination

The physics of atoms and quanta introduction to experiments and theory

CERN Document Server

Haken, Hermann; Brewer, William D

2005-01-01

The Physics of Atoms and Quanta is a thorough introduction to experiments and theory in this field. Every classical and modern aspect is included and discussed in detail. The new edition is completely revised, new sections on atoms in strong electric fields and high magnetic fields complete the comprehensive coverage of all topics related to atoms and quanta. All new developments, such as new experiments on quantum entanglement, the quantum computer, quantum information, the Einstein-Podolsky-Rosen paradoxon, Bell's inequality, Schrödinger's cat, decoherence, Bose-Einstein-Condensation and the atom laser are discussed. Over 170 problems and their solutions help deepen the insight in this subject area and make this book a real study text. The second and more advanced book by the same authors entitled "Molecular Physics and Elements of Quantum Chemistry" is the completion of this unique textbook.

Multiphoton processes for atoms in intense electromagnetic fields

Energy Technology Data Exchange (ETDEWEB)

Collins, L.A.; Abdallah, J.; Csanak, G.

1995-12-31

Lasers from table-top to giant ICF facilities that produce intense electromagnetic fields (10{sup 14}-10{sup 21} W/cm{sup 2}) have become important tools in probing the intricate nature of matter-radiation interactions. At such intensities, the laser field equals or exceeds that which binds electrons to an atom or molecule, and a new realm of physics opens in which perturbation theory may no longer suffice. We are developing several sophisticated techniques for treating atoms in such a regime, concentrating on two-photon X-ray absorption in intermediate-weight atoms and on laser-assisted electron-atom collisions. We perform most calculations in a time-independent frame in which field-free scattering formalisms can be invoked. We also investigate time-dependent methods in order to study transient effects. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

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.

Nonlinear spectroscopy of the Rydberg atoms

International Nuclear Information System (INIS)

Delone, N.B.; Krajnov, V.P.; Shepelyanskij, D.L.

1984-01-01

The results of investigation into perturbation of Rydberg states (RS) of atoms in an outer alternating field (OAF) are discussed. Both highly excited states of hydrogen atom at the energy Esub(n)=-1/2n -2 (n>>1 - basic quantum number) and excited states of compound atoms with energy Esub(nl)=-1/2(n*) -2 where n*=n-delta sub(e)-effective basic quantum number, delta sub(e)-quantum defect, are implied by RS. Perturbation of atomic state in the OAF is determined not only by field strength E, but by its frequency ω as well. During OAF inclusion the initial state Esub(lambda) transits to quasienergetic at the energy Esub(lambda)(E)+-kω, where K=0, +-1, +-2, .... Solutions of the problem of quasienergetic level population is obtained only for some simple particular cases. A simple case, when a real multilevel atom is replaced by a model system comprising one bound electron state with the basic quantum number n-model of the insulated level (MIL) is considered. Conditions of MIL applicability are discussed. Estimation of critical OAF strength at which MIL approximation becomes faulty are discussed. It is stated that any consideration of RS perturbation in OAF claiming to exceeding MIL frames should comprise consideration of ionization processes. If one keeps to the frames of OAF; the strength of which is lower than the determined critical values then MIL is true and use of this model permits to correctly describe the main features of RS perturbation in an alternating field

EDITORIAL: From reciprocal space to real space in surface science From reciprocal space to real space in surface science

Science.gov (United States)

Bartels, Ludwig; Ernst, Karl-Heinz

2012-09-01

This issue is dedicated to Karl-Heinz Rieder on the occasion of his 70th birthday. It contains contributions written by his former students and colleagues from all over the world. Experimental techniques based on free electrons, such as photoelectron spectroscopy, electron microscopy and low energy electron diffraction (LEED), were foundational to surface science. While the first revealed the band structures of materials, the second provided nanometer scale imagery and the latter elucidated the atomic scale periodicity of surfaces. All required an (ultra-)high vacuum, and LEED illustrated impressively that adsorbates, such as carbon monoxide, hydrogen or oxygen, can markedly and periodically restructure surfaces from their bulk termination, even at pressures ten orders of magnitude or more below atmospheric. Yet these techniques were not generally able to reveal atomic scale surface defects, nor could they faithfully show adsorption of light atoms such as hydrogen. Although a complete atom, helium can also be regarded as a wave with a de Broglie wavelength that allows the study of surface atomic periodicities at a delicateness and sensitivity exceeding that of electrons-based techniques. In combination, these and other techniques generated insight into the periodicity of surfaces and their vibrational properties, yet were limited to simple and periodic surface setups. All that changed with the advent of scanning tunneling microscopy (STM) roughly 30 years ago, allowing real space access to surface defects and individual adsorbates. Applied at low temperatures, not only can STM establish a height profile of surfaces, but can also perform spectroscopy and serve as an actuator capable of rearranging individual species at atomic scale resolution. The direct and intuitive manner in which STM provided access as a spectator and as an actor to the atomic scale was foundational to today's surface science and to the development of the concepts of nanoscience in general. The

Development of radiation hardened robot for nuclear facility - Development of real-time stereo object tracking system using the optical correlator

Energy Technology Data Exchange (ETDEWEB)

Kim, Eun Soo; Lee, S. H.; Lee, J. S. [Kwangwoon University, Seoul (Korea)

2000-03-01

Object tracking, through Centroide method used in the KAERI-M1 Stereo Robot Vision System developed at Atomic Research Center, is too sensitive to target's light variation and because it has a fragility which can't reflect the surrounding background, the application in the actual condition is very limited. Also the correlation method can constitute a relatively stable object tracker in noise features but the digital calculation amount is too massive in image correlation so real time materialization is limited. So the development of Optical Correlation based on Stereo Object Tracking System using high speed optical information processing technique will put stable the real time stereo object tracking system and substantial atomic industrial stereo robot vision system to practical use. This research is about developing real time stereo object tracking algorithm using optical correlation system through the technique which can be applied to Atomic Research Center's KAERI-M1 Stereo Vision Robot which will be used in atomic facility remote operations. And revise the stereo disparity using real time optical correlation technique, and materializing the application of the stereo object tracking algorithm to KAERI-M1 Stereo Robot. 19 refs., 45 figs., 2 tabs. (Author)

Atomic-scale structure of single-layer MoS2 nanoclusters

DEFF Research Database (Denmark)

Helveg, S.; Lauritsen, J. V.; Lægsgaard, E.

2000-01-01

We have studied using scanning tunneling microscopy (STM) the atomic-scale realm of molybdenum disulfide (MoS2) nanoclusters, which are of interest as a model system in hydrodesulfurization catalysis. The STM gives the first real space images of the shape and edge structure of single-layer MoS2...

Atomization of U3Si2 for research reactor fuel

International Nuclear Information System (INIS)

Kim, C.K.; Kim, K.H.; Lee, C.T.; Kuk, I.H.

1995-01-01

Rotating disk atomization technique is applied to KMRR (Korea Multi-purpose Research Reactor) fuel fabrication. A rotating disk atomizer is designed and manufactured locally and U-4.0 wt. % Si alloy powders are produced. The atomized powders are heat-treated to transform into U 3 Si and the mixture of U 3 Si and Al are extruded to fuel meat. Most of the atomized powders are spherical in shape. The microstructure of the powder is fine due to the rapid solidification. The time required for peritectoid reaction is reduced due to the fine microstructures and the resultant U 3 Si grain size is finer than ever obtained from ingot process. The mechanical properties of the fuel meat are improved: yield strength about 30 %, tensile strength 10% and elongation 250 % increased. (author)

16. International Conference on Atomic Collisions in Solids. Book of abstracts

Energy Technology Data Exchange (ETDEWEB)

Paul, H; Bauer, P; Semrad, D [ed.; Johannes Kepler Univ., Linz (Austria). Inst. fuer Experimentalphysik

1996-12-31

In this conference book of abstracts the following topics are treated: The interaction of atomic, molecular or ion beams with surfaces of solid metals and crystals, scattering and collisions, ion bombardment, ion channeling, energy losses and charge exchange, thin films, secondary emission, the Auger effect, sputtering of particles and atomic and molecular clusters. Thereby not only experimental results are presented but also computerized simulation methods are applied. (Suda).

16. International Conference on Atomic Collisions in Solids. Book of abstracts

International Nuclear Information System (INIS)

Paul, H.; Bauer, P.; Semrad, D.

1995-01-01

In this conference book of abstracts the following topics are treated: The interaction of atomic, molecular or ion beams with surfaces of solid metals and crystals, scattering and collisions, ion bombardment, ion channeling, energy losses and charge exchange, thin films, secondary emission, the Auger effect, sputtering of particles and atomic and molecular clusters. Thereby not only experimental results are presented but also computerized simulation methods are applied. (Suda)

Quantum dynamics of atoms in a resonator-generated optical lattice

International Nuclear Information System (INIS)

Maschler, C.; Ritsch, H.

2005-01-01

Full text: We investigate the quantum motion of coherently driven ultracold atoms in the field of a damped high-Q optical cavity mode. The laser field is chosen far detuned from the atomic transition but close to a cavity resonance, so that spontaneous emission is strongly suppressed but a coherent field builds up in the resonator by stimulated scattering. On one hand the shape of the atomic wave function determines the field dynamics via the magnitude of the scattering and the effective refractive index the atoms create for the mode. The mode intensity on the other hand determines the optical dipole force on the atoms.The system shows rich atom-field dynamics including self organization, self-trapping, cooling or heating. In the limit of deep trapping we are able to derive a system of closed, coupled equations for a finite set of atomic expectation values and the field. This allows us to determine the self-consistent ground state of the system as well as the eigenfrequencies and damping rates for excitations. To treat several atoms in more detail we introduce the Bose-Hubbard model. This allows us to investigate several aspects of the quantum motion of the atoms inside the cavity. (author)

Local energy equation for two-electron atoms and relation between kinetic energy and electron densities

International Nuclear Information System (INIS)

March, N.H.

2002-08-01

In early work, Dawson and March [J. Chem. Phys. 81, 5850 (1984)] proposed a local energy method for treating both Hartree-Fock and correlated electron theory. Here, an exactly solvable model two-electron atom with pure harmonic interactions is treated in its ground state in the above context. A functional relation between the kinetic energy density t(r) at the origin r=0 and the electron density p(r) at the same point then emerges. The same approach is applied to the Hookean atom; in which the two electrons repel with Coulombic energy e 2 /r 12 , with r 12 the interelectronic separation, but are still harmonically confined. Again the kinetic energy density t(r) is the focal point, but now generalization away from r=0 is also effected. Finally, brief comments are added about He-like atomic ions in the limit of large atomic number. (author)

Characteristics of single-atom trapping in a magneto-optical trap with a high magnetic-field gradient

International Nuclear Information System (INIS)

Yoon, Seokchan; Choi, Youngwoon; Park, Sangbum; Ji, Wangxi; Lee, Jai-Hyung; An, Kyungwon

2007-01-01

A quantitative study on characteristics of a magneto-optical trap with a single or a few atoms is presented. A very small number of 85 Rb atoms were trapped in a micron-size magneto-optical trap with a high magnetic-field gradient. In order to find the optimum condition for a single-atom trap, we have investigated how the number of atoms and the size of atomic cloud change as various experimental parameters, such as a magnetic-field gradient and the trapping laser intensity and detuning. The averaged number of atoms was measured very accurately with a calibration procedure based on the single-atom saturation curve of resonance fluorescence. In addition, the number of atoms in a trap could be controlled by suppressing stochastic loading events by means of a real-time active feedback on the magnetic-field gradient

Scattering resonances of ultracold atoms in confined geometries

International Nuclear Information System (INIS)

Saeidian, Shahpoor

2008-01-01

Subject of this thesis is the investigation of the quantum dynamics of ultracold atoms in confined geometries. We discuss the behavior of ground state atoms inside a 3D magnetic quadrupole field. Such atoms in enough weak magnetic fields can be approximately treated as neutral point-like particles. Complementary to the well-known positive energy resonances, we point out the existence of short-lived negative energy resonances. The latter originate from a fundamental symmetry of the underlying Hamiltonian. We drive a mapping of the two branches of the spectrum. Moreover, we analyze atomic hyperfine resonances in a magnetic quadrupole field. This corresponds to the case for which both the hyperfine and Zeeman interaction, are comparable, and should be taken into account. Finally, we develop a general grid method for multichannel scattering of two atoms in a two-dimensional harmonic confinement. With our approach we analyze transverse excitations/deexcitations in the course of the collisional process (distinguishable or identical atoms) including all important partial waves and their couplings due to the broken spherical symmetry. Special attention is paid to suggest a non-trivial extension of the CIRs theory developed so far only for the single-mode regime and zero-energy limit. (orig.)

Scattering resonances of ultracold atoms in confined geometries

Energy Technology Data Exchange (ETDEWEB)

Saeidian, Shahpoor

2008-06-18

Subject of this thesis is the investigation of the quantum dynamics of ultracold atoms in confined geometries. We discuss the behavior of ground state atoms inside a 3D magnetic quadrupole field. Such atoms in enough weak magnetic fields can be approximately treated as neutral point-like particles. Complementary to the well-known positive energy resonances, we point out the existence of short-lived negative energy resonances. The latter originate from a fundamental symmetry of the underlying Hamiltonian. We drive a mapping of the two branches of the spectrum. Moreover, we analyze atomic hyperfine resonances in a magnetic quadrupole field. This corresponds to the case for which both the hyperfine and Zeeman interaction, are comparable, and should be taken into account. Finally, we develop a general grid method for multichannel scattering of two atoms in a two-dimensional harmonic confinement. With our approach we analyze transverse excitations/deexcitations in the course of the collisional process (distinguishable or identical atoms) including all important partial waves and their couplings due to the broken spherical symmetry. Special attention is paid to suggest a non-trivial extension of the CIRs theory developed so far only for the single-mode regime and zero-energy limit. (orig.)

Atoms

International Nuclear Information System (INIS)

Fuchs, Alain; Villani, Cedric; Guthleben, Denis; Leduc, Michele; Brenner, Anastasios; Pouthas, Joel; Perrin, Jean

2014-01-01

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)

Atomic clocks: A brief history and current status of research in India

Indian Academy of Sciences (India)

2014-02-19

Feb 19, 2014 ... Time and Frequency Division, CSIR-National Physical Laboratory, .... gen atoms, for example, which travel at a speed of about 1600 m/s at ..... sition card (DAQ) and real-time processing of the data on a LabVIEW platform.

Characterization of a 5-eV neutral atomic oxygen beam facility

Science.gov (United States)

Vaughn, J. A.; Linton, R. C.; Carruth, M. R., Jr.; Whitaker, A. F.; Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.

1991-01-01

An experimental effort to characterize an existing 5-eV neutral atomic oxygen beam facility being developed at Princeton Plasma Physics Laboratory is described. This characterization effort includes atomic oxygen flux and flux distribution measurements using a catalytic probe, energy determination using a commercially designed quadrupole mass spectrometer (QMS), and the exposure of oxygen-sensitive materials in this beam facility. Also, comparisons were drawn between the reaction efficiencies of materials exposed in plasma ashers, and the reaction efficiencies previously estimated from space flight experiments. The results of this study show that the beam facility is capable of producing a directional beam of neutral atomic oxygen atoms with the needed flux and energy to simulate low Earth orbit (LEO) conditions for real time accelerated testing. The flux distribution in this facility is uniform to +/- 6 percent of the peak flux over a beam diameter of 6 cm.

Hot spring therapy of atomic bomb exposed patients, (9)

Energy Technology Data Exchange (ETDEWEB)

Hatta, O [Balneogic Sanatorium for the Atomic Bomb Injured Beppu, Oita (Japan); Tsuji, H

1978-03-01

The following description shows the statistics and the results of medical examinatin concerning the patients utilized Beppu Atomic Bomb Center from April, 1977, to March, 1978. Number of persons utilized the center was 3904, and 20285 man-days in total. Number of case treated there was 268. Number of diseases amounted to 442 of 66 sorts, excluding temporary of acute diseases such as acute entergastritis and cold diseases, etc. According to the report by the Ministry of Health and Welfare, atomic bomb-exposed persons show twice as much rate of incidence as normal persons, and owing to aging, many of them have more than two kinds of diseases. Among the diseases, 60 cases were hypertension, 32 heart disease, 30 knee-arthritis, 26 diabetes, 25 hepatitis, 23 spondylosis deformans, etc. Among 268 cases treated by hot spring therapy, 6 were totally cured, and 252 showed alleviation, while 10 showed no change.

Physically representative atomistic modeling of atomic-scale friction

Science.gov (United States)

Dong, Yalin

interesting physical process is buried between the two contact interfaces, thus makes a direct measurement more difficult. Atomistic simulation is able to simulate the process with the dynamic information of each single atom, and therefore provides valuable interpretations for experiments. In this, we will systematically to apply Molecular Dynamics (MD) simulation to optimally model the Atomic Force Microscopy (AFM) measurement of atomic friction. Furthermore, we also employed molecular dynamics simulation to correlate the atomic dynamics with the friction behavior observed in experiments. For instance, ParRep dynamics (an accelerated molecular dynamic technique) is introduced to investigate velocity dependence of atomic friction; we also employ MD simulation to "see" how the reconstruction of gold surface modulates the friction, and the friction enhancement mechanism at a graphite step edge. Atomic stick-slip friction can be treated as a rate process. Instead of running a direction simulation of the process, we can apply transition state theory to predict its property. We will have a rigorous derivation of velocity and temperature dependence of friction based on the Prandtl-Tomlinson model as well as transition theory. A more accurate relation to prediction velocity and temperature dependence is obtained. Furthermore, we have included instrumental noise inherent in AFM measurement to interpret two discoveries in experiments, suppression of friction at low temperature and the attempt frequency discrepancy between AFM measurement and theoretical prediction. We also discuss the possibility to treat wear as a rate process.

Atomic force microscopy applied to the quantification of nano-precipitates in thermo-mechanically treated microalloyed steels

Energy Technology Data Exchange (ETDEWEB)

Renteria-Borja, Luciano [Instituto Tecnologico de Morelia, Av. Tecnologico No. 1500, Lomas de Santiaguito, 58120 Morelia (Mexico); Hurtado-Delgado, Eduardo, E-mail: hurtado@itmorelia.edu.mx [Instituto Tecnologico de Morelia, Av. Tecnologico No. 1500, Lomas de Santiaguito, 58120 Morelia (Mexico); Garnica-Gonzalez, Pedro [Instituto Tecnologico de Morelia, Av. Tecnologico No. 1500, Lomas de Santiaguito, 58120 Morelia (Mexico); Dominguez-Lopez, Ivan; Garcia-Garcia, Adrian Luis [Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada-IPN Unidad Queretaro, Cerro Blanco No. 141, Colinas del Cimatario, 76090 Queretaro (Mexico)

2012-07-15

Quantification of nanometer-size precipitates in microalloyed steels has been traditionally performed using transmission electron microscopy (TEM), in spite of its complicated sample preparation procedures, prone to preparation errors and sample perturbation. In contrast to TEM procedures, atomic force microscopy (AFM) is performed on the as-prepared specimen, with sample preparation requirements similar to those for optical microscopy (OM), rendering three-dimensional representations of the sample surface with vertical resolution of a fraction of a nanometer. In AFM, contrast mechanisms are directly related to surface properties such as topography, adhesion, and stiffness, among others. Chemical etching was performed using 0.5% nital, at time intervals between 4 and 20 s, in 4 s steps, until reaching the desired surface finish. For the present application, an average surface-roughness peak-height below 200 nm was sought. Quantification results of nanometric precipitates were obtained from the statistical analysis of AFM images of the microstructure developed by microalloyed Nb and V-Mo steels. Topography and phase contrast AFM images were used for quantification. The results obtained using AFM are consistent with similar TEM reports. - Highlights: Black-Right-Pointing-Pointer We quantified nanometric precipitates in Nb and V-Mo microalloyed steels using AFM. Black-Right-Pointing-Pointer Microstructures of the thermo-mechanically treated microalloyed steels were used. Black-Right-Pointing-Pointer Topography and phase contrast AFM images were used for quantification. Black-Right-Pointing-Pointer AFM results are comparable with traditionally obtained TEM measurements.

Capital renewal as a real option

NARCIS (Netherlands)

Reindorp, M.J.; Fu, M.C.

2011-01-01

We consider the timing of replacement of obsolete subsystems within an extensive, complex infrastructure. Such replacement action, known as capital renewal, must balance uncertainty about future profitability against uncertainty about future renewal costs. Treating renewal investments as real

26 CFR 1.856-1 - Definition of real estate investment trust.

Science.gov (United States)

2010-04-01

... determining whether distributions by a real estate investment trust are to be treated as in exchange for stock; (4) Section 305 applies to distributions by a real estate investment trust of its own stock; (5... “shareholders” include holders of beneficial interest in a real estate investment trust, the terms “stock...

Real-life radiation burden to relatives of patients treated with iodine-131: a study in eight centres in Flanders (Belgium)

International Nuclear Information System (INIS)

Monsieurs, M.; Thierens, H.; Dierckx, R.A.; Casier, K.; Simons, M.; Baere, E. de; Ridder, L. de; Saedeleer, C. de; Winter, H. de; Lippens, M.; Imschoot, S. van; Wulfrank, D.

1998-01-01

In view of the EURATOM 96/29 regulations, a prospective multicentre study was performed to evaluate the present guidelines given to relatives of patients treated with iodine-131 for both thyroid carcinoma and thyrotoxicosis, based on the real-life radiation burden. This study comprised 166 measurements carried out on a group of 94 relatives of 65 patients. All relatives wore a thermoluminescent dosemeter (TLD) on the wrist for 7 days. Sixty-one relatives agreed to wear another TLD for an additional 7 days. TLD were placed on nine patients' bedside tables. The eight participating centres were arbitrarily divided into three groups according to the period of time they advised their patients to sleep separately. Groups I, II and III respectively advised their patients to sleep separately for 0, 7-10 and 14-21 days. The median dose received by in-living relatives of thyroid carcinoma patients during the 14 days following hospital discharge was 281 μSv (doses to infinity not calculated); the median dose to infinity received by in-living relatives of ambulatory treated thyrotoxicosis patients was 596 μSv, as compared with 802 μSv for in-living relatives of hospitalised thyrotoxicosis patients. In general the children of patients received a significantly (P 131 I, while still following the ALARA principle. (orig.)

Atomic imaging by x-ray-fluorescence holography and electron-emission holography: A comparative theoretical study

International Nuclear Information System (INIS)

Len, P.M.; Thevuthasan, S.; Fadley, C.S.; Kaduwela, A.P.; Van Hove, M.A.

1994-01-01

We consider from a theoretical viewpoint the direct imaging of atoms at and near the surfaces of solids by both x-ray-fluorescence holography (XFH) and electron-emission holography (EEH). The more ideal nature of x-ray scattering makes XFH images superior to those in single-energy EEH. The overlap of real and twin features for pairs of atoms at ±a can cause their XFH or EEH atomic images to cancel for certain combinations of wave vector and |a|. The relative merits of XFH and EEH for structure studies are considered

Probing stem cell differentiation using atomic force microscopy

International Nuclear Information System (INIS)

Liang, Xiaobin; Shi, Xuetao; Ostrovidov, Serge; Wu, Hongkai; Nakajima, Ken

2016-01-01

Graphical abstract: - Highlights: • Atomic force microscopy (AFM) was developed to probe stem cell differentiation. • The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. • AFM is a facile and useful tool for monitoring stem cell differentiation in a non-invasive manner. - Abstract: A real-time method using atomic force microscopy (AFM) was developed to probe stem cell differentiation by measuring the mechanical properties of cells and the extracellular matrix (ECM). The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. It is clear that AFM is a facile and useful tool for monitoring the differentiation of stem cells in a non-invasive manner.

Probing stem cell differentiation using atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Liang, Xiaobin [Graduate School of Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8550 (Japan); Shi, Xuetao, E-mail: mrshixuetao@gmail.com [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Ostrovidov, Serge [WPI-Advanced Institute for Materials Research, Tohoku University, Sendai (Japan); Wu, Hongkai, E-mail: chhkwu@ust.hk [Department of Chemistry & Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China); Nakajima, Ken [Graduate School of Science and Engineering, Tokyo Institute of Technology, Ookayama 2-12-1, Meguro-ku, Tokyo 152-8550 (Japan)

2016-03-15

Graphical abstract: - Highlights: • Atomic force microscopy (AFM) was developed to probe stem cell differentiation. • The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. • AFM is a facile and useful tool for monitoring stem cell differentiation in a non-invasive manner. - Abstract: A real-time method using atomic force microscopy (AFM) was developed to probe stem cell differentiation by measuring the mechanical properties of cells and the extracellular matrix (ECM). The mechanical properties of stem cells and their ECMs can be used to clearly distinguish specific stem cell-differentiated lineages. It is clear that AFM is a facile and useful tool for monitoring the differentiation of stem cells in a non-invasive manner.

Stark effect in a hydrogenic atom or ion treated by the phase-integral method with adjoined papers by A. Hökback and P. O. Fröman

CERN Document Server

Fröman, Nanny

2008-01-01

This book treats the Stark effect of a hydrogenic atom or ion in a homogeneous electric field. It begins with a thorough review of previous work in this field since 1926. After the Schrödinger equation has been separated with respect to time dependence, centre of mass motion and internal motion, followed by a discussion of its eigenfunctions, the exact development in time of the probability amplitude for a decaying state is obtained by means of a formula analogous to the Fock-Krylov theorem. From this formula one obtains by means of the phase-integral approximation generated from a particular

Single-atom lasing induced atomic self-trapping

International Nuclear Information System (INIS)

Salzburger, T.; Ritsch, H.

2004-01-01

We study atomic center of mass motion and field dynamics of a single-atom laser consisting of a single incoherently pumped free atom moving in an optical high-Q resonator. For sufficient pumping, the system starts lasing whenever the atom is close to a field antinode. If the field mode eigenfrequency is larger than the atomic transition frequency, the generated laser light attracts the atom to the field antinode and cools its motion. Using quantum Monte Carlo wave function simulations, we investigate this coupled atom-field dynamics including photon recoil and cavity decay. In the regime of strong coupling, the generated field shows strong nonclassical features like photon antibunching, and the atom is spatially confined and cooled to sub-Doppler temperatures. (author)

Variational Perturbation Treatment of the Confined Hydrogen Atom

Science.gov (United States)

Montgomery, H. E., Jr.

2011-01-01

The Schrodinger equation for the ground state of a hydrogen atom confined at the centre of an impenetrable cavity is treated using variational perturbation theory. Energies calculated from variational perturbation theory are comparable in accuracy to the results from a direct numerical solution. The goal of this exercise is to introduce the…

Ultracold atoms on atom chips

DEFF Research Database (Denmark)

Krüger, Peter; Hofferberth, S.; Haller, E.

2005-01-01

Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom-surface distances can be reduced to microns. We discuss experiments in this regime...

Neutral atom beam technique enhances bioactivity of PEEK

International Nuclear Information System (INIS)

Khoury, Joseph; Kirkpatrick, Sean R.; Maxwell, Melissa; Cherian, Raymond E.; Kirkpatrick, Allen; Svrluga, Richard C.

2013-01-01

Polyetheretherketone (PEEK) is currently gaining popularity in orthopedic and spinal applications but has potential drawbacks in use. PEEK is biocompatible, similar in elasticity to bone, and radiolucent; however, it has been shown to be inert and does not integrate well with bone. Recent efforts have focused on increasing the bioactivity of PEEK by modifying the surface to improve the bone-implant interface. We have employed a novel Accelerated Neutral Atom Beam technique (ANAB) to enhance the bioactivity of PEEK. ANAB employs an intense beam of cluster-like packets of accelerated unbonded neutral argon (Ar) gas atoms. These beams are created by first producing a highly energetic Gas Cluster Ion Beam (GCIB) comprised of van der Waals bonded Ar atoms, then transferring energy to the clusters so as to cause release of most of the interatomic bonds, and finally deflecting away the remaining electrically charged cluster cores of still bonded atoms. We identified that ANAB treatment of PEEK results in nanometer scale surface modifications as well as increased surface hydrophilicity. Human osteoblasts seeded onto the surface of ANAB-treated PEEK exhibited enhanced growth as compared to control PEEK as evidenced by cell proliferation assays and microscopy. This increase in bioactivity resulted in cell proliferation levels comparable to native titanium. An in vivo study using a rat calvarial critical size defect model revealed enhanced osseointegration where bone tissue formation was evident only on the ANAB treated PEEK. Taken together, these data suggest that ANAB treatment of PEEK has the potential to enhance its bioactivity, resulting in bone formation and significantly decreasing osseointegration time of orthopedic and spinal implants

CHAINS-PC, Decay Chain Atomic Densities

International Nuclear Information System (INIS)

1994-01-01

1 - Description of program or function: CHAINS computes the atom density of members of a single radioactive decay chain. The linearity of the Bateman equations allows tracing of interconnecting chains by manually accumulating results from separate calculations of single chains. Re-entrant loops can be treated as extensions of a single chain. Losses from the chain are also tallied. 2 - Method of solution: The Bateman equations are solved analytically using double-precision arithmetic. Poles are avoided by small alterations of the loss terms. Multigroup fluxes, cross sections, and self-shielding factors entered as input are used to compute the effective specific reaction rates. The atom densities are computed at any specified times. 3 - Restrictions on the complexity of the problem: Maxima of 100 energy groups, 100 time values, 50 members in a chain

TDHF study of the He+ collision on atomic He targets at the 8Be ground state energy

International Nuclear Information System (INIS)

Cai, J.; Shoppa, T.D.; Langanke, K.

1997-01-01

Experimentally the 8 Be ground state resonance has been studied in He + collisions on atomic He atoms. The nuclear resonance manifests itself by satellite resonance lines corresponding to different electron configurations of the Be ion. Experimentally a large probability for the emission of one electron has been deduced. We study the atomic He + +He collision within a model in which the evolution of the electron wavefunction is treated dynamically in the TDHF scheme, and the motion of the nuclei is treated classically. In agreement with experiment we find a large probability for one electron to be emitted into the continuum during the lifetime of the 8 Be ground state resonance. (orig.). With 2 figs., 1 tab

Creation and development of Bohr's theory (on the 90th anniversary of the Bohr theory of the atom)

International Nuclear Information System (INIS)

Milant'ev, Vladimir P

2004-01-01

The history of the creation and development of Bohr's atomic theory is discussed. Even now, with a consistent quantum theory available, Bohr's theory is not simply the property of history, of methodological interest only. To this day, the ideas of the theory not only provide an excellent introduction to atomic physics, but are also used successfully in treating atomic Rydberg states, exotic atoms, etc. (from the history of physics)

A real-world analysis of glycemic control among patients with type 2 diabetes treated with canagliflozin versus dapagliflozin.

Science.gov (United States)

Blonde, Lawrence; Patel, Charmi; Bookhart, Brahim; Pfeifer, Michael; Chen, Yen-Wen; Wu, Bingcao

2018-06-01

This US retrospective cohort study compared the real-world effectiveness of canagliflozin 300 mg versus dapagliflozin 10 mg on HbA1c reduction in patients with type 2 diabetes mellitus (T2DM). Patients initiated on canagliflozin 300 mg or dapagliflozin 10 mg were identified from de-identified claims data in the Optum Clinformatics database (1 January 2014-30 September 2016). Propensity score matching was used to create balanced cohorts. The primary outcome was the proportion of patients with HbA1c 9.0% (HEDIS poor control), absolute change in HbA1c, and treatment patterns. At 6 months post-index (intent-to-treat population), a significantly higher proportion of patients in the canagliflozin 300 mg versus dapagliflozin 10 mg cohort achieved HbA1c 9.0%. Mean HbA1c reduction was -1.17% with canagliflozin 300 mg and -0.91% with dapagliflozin 10 mg (difference of -0.26%; p = .0049). HbA1c results from a sensitivity analysis in the on-treatment population were consistent with the primary analysis. Patients in the canagliflozin 300 mg versus dapagliflozin 10 mg cohort were less likely to discontinue treatment (OR [95% CI]: 0.75 [0.57, 0.99]; p = .0400) or switch medication (OR [95% CI]: 0.72 [0.54, 0.96]; p = .0229). In this real-world study, patients with T2DM initiated on canagliflozin 300 mg had better HbA1c goal attainment and larger HbA1c reduction than patients initiated on dapagliflozin 10 mg.

Treatment Efficacy and Compliance in Patients with Diabetic Macular Edema Treated with Ranibizumab in a Real-Life Setting

Directory of Open Access Journals (Sweden)

Anne-Laurence Best

2018-01-01

Full Text Available Purpose. To assess real-life efficacy of ranibizumab and treatment compliance of patients with vision loss secondary to diabetic macular edema (DME. Methods. A retrospective study was conducted in DME patients treated with ranibizumab. Patients were monitored every 4 weeks for visual acuity (VA and central retinal thickness (CRT by SD-OCT. All patients received a loading dose of 3 monthly injections followed by retreatments on an as-needed basis. The primary endpoint was the change in VA at M12. Patient compliance to the follow-up and the correlation between the injection number and VA were also investigated. Compliance was compared to that of neovascular age-related macular degeneration (nAMD patients. Results. Seventy-two eyes of 55 consecutive DME patients were included. At baseline, the mean VA was 56.5 letters and CRT was 470 μm. At M12, the mean VA was 63.4 letters (p 70 letters, the mean VA change was +6.9 letters, and the mean CRT was 361.9 μm (p=0.0001 after a mean number of 5.33 intravitreal injections. In patients who received ≥7 injections, the VA gain and final VA were significantly higher than in patients who received <7 injections. At M12, 25.45% of DME patients were lost to follow-up versus 16.8% of nAMD patients (n=55. Discussion/Conclusion. Our study confirms the real-life efficacy of ranibizumab in DME at M12 and the need for a large number of injections to achieve better visual outcomes. We also showed a trend to a lower compliance in diabetic versus nAMD patients.

Sub-nanometer resolution XPS depth profiling: Sensing of atoms

Energy Technology Data Exchange (ETDEWEB)

Szklarczyk, Marek, E-mail: szklarcz@chem.uw.edu.pl [Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw (Poland); Shim-Pol, ul. Lubomirskiego 5, 05-080 Izabelin (Poland); Macak, Karol; Roberts, Adam J. [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom); Takahashi, Kazuhiro [Kratos XPS Section, Shimadzu Corp., 380-1 Horiyamashita, Hadano, Kanagawa 259-1304 (Japan); Hutton, Simon [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom); Głaszczka, Rafał [Shim-Pol, ul. Lubomirskiego 5, 05-080 Izabelin (Poland); Blomfield, Christopher [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom)

2017-07-31

Highlights: • Angle resolved photoelectron depth profiling of nano thin films. • Sensing atomic position in SAM films. • Detection of direction position of adsorbed molecules. - Abstract: The development of a method capable of distinguishing a single atom in a single molecule is important in many fields. The results reported herein demonstrate sub-nanometer resolution for angularly resolved X-ray photoelectron spectroscopy (ARXPS). This is made possible by the incorporation of a Maximum Entropy Method (MEM) model, which utilize density corrected electronic emission factors to the X-ray photoelectron spectroscopy (XPS) experimental results. In this paper we report on the comparison between experimental ARXPS results and reconstructed for both inorganic and organic thin film samples. Unexpected deviations between experimental data and calculated points are explained by the inaccuracy of the constants and standards used for the calculation, e.g. emission factors, scattering intensity and atomic density through the studied thickness. The positions of iron, nitrogen and fluorine atoms were determined in the molecules of the studied self-assembled monolayers. It has been shown that reconstruction of real spectroscopic data with 0.2 nm resolution is possible.

Nonequilibrium forces between neutral atoms mediated by a quantum field

International Nuclear Information System (INIS)

Behunin, Ryan O.; Hu, Bei-Lok

2010-01-01

We study forces between two neutral atoms, modeled as three-dimensional harmonic oscillators, arising from mutual influences mediated by an electromagnetic field but not from their direct interactions. We allow as dynamical variables the center-of-mass motion of the atom, its internal degrees of freedom, and the quantum field treated relativistically. We adopt the method of nonequilibrium quantum field theory which can provide a first-principles, systematic, and unified description including the intrinsic and induced dipole fluctuations. The inclusion of self-consistent back-actions makes possible a fully dynamical description of these forces valid for general atom motion. In thermal equilibrium we recover the known forces--London, van der Waals, and Casimir-Polder--between neutral atoms in the long-time limit. We also reproduce a recently reported force between atoms when the system is out of thermal equilibrium at late times. More noteworthy is the discovery of the existence of a type of (or identification of the source of some known) interatomic force which we call the ''entanglement force,'' originating from the quantum correlations of the internal degrees of freedom of entangled atoms.

Real-time personal exposure and health condition monitoring system

Energy Technology Data Exchange (ETDEWEB)

Saitou, Isamu; Kanda, Hiroaki; Asai, Akio; Takeishi, Naoki; Ota, Yoshito [Hitachi Aloka Medical, Ltd., Measuring Systems Engineering Dept., Tokyo (Japan); Hanawa, Nobuhiro; Ueda, Hisao; Kusunoki, Tsuyoshi; Ishitsuka, Etsuo; Kawamura, Hiroshi [Japan Atomic Energy Agency, Oarai Research and Development Center, Oarai, Ibaraki (Japan)

2012-03-15

JAEA (Japan Atomic Energy Agency) and HAM (Hitachi Aloka Medical, Ltd) have proposed novel monitoring system for workers of nuclear facility. In these facilities, exposure management for workers is mainly used access control and personal exposure recordings. This system is currently only for reports management but is not confirmative for surveillance when work in progress. Therefore, JAEA and HAM integrate access control and personal exposure recordings and two real-time monitoring systems which are position sensing and vital sign monitor. Furthermore change personal exposure management to real-time management, this system integration prevents workers from risk of accidents, and makes possible take appropriate action quickly. This novel system is going to start for tentative operation, using position sensing and real-time personal dosimeter with database in Apr. 2012. (author)

Kinetic and spectral descriptions of autoionization phenomena associated with atomic processes in plasmas

Science.gov (United States)

Jacobs, Verne L.

2017-06-01

This investigation has been devoted to the theoretical description and computer modeling of atomic processes giving rise to radiative emission in energetic electron and ion beam interactions and in laboratory plasmas. We are also interested in the effects of directed electron and ion collisions and of anisotropic electric and magnetic fields. In the kinetic-theory description, we treat excitation, de-excitation, ionization, and recombination in electron and ion encounters with partially ionized atomic systems, including the indirect contributions from processes involving autoionizing resonances. These fundamental collisional and electromagnetic interactions also provide particle and photon transport mechanisms. From the spectral perspective, the analysis of atomic radiative emission can reveal detailed information on the physical properties in the plasma environment, such as non-equilibrium electron and charge-state distributions as well as electric and magnetic field distributions. In this investigation, a reduced-density-matrix formulation is developed for the microscopic description of atomic electromagnetic interactions in the presence of environmental (collisional and radiative) relaxation and decoherence processes. Our central objective is a fundamental microscopic description of atomic electromagnetic processes, in which both bound-state and autoionization-resonance phenomena can be treated in a unified and self-consistent manner. The time-domain (equation-of-motion) and frequency-domain (resolvent-operator) formulations of the reduced-density-matrix approach are developed in a unified and self-consistent manner. This is necessary for our ultimate goal of a systematic and self-consistent treatment of non-equilibrium (possibly coherent) atomic-state kinetics and high-resolution (possibly overlapping) spectral-line shapes. We thereby propose the introduction of a generalized collisional-radiative atomic-state kinetics model based on a reduced

Atomic collisions related to atomic laser isotope separation

International Nuclear Information System (INIS)

Shibata, Takemasa

1995-01-01

Atomic collisions are important in various places in atomic vapor laser isotope separation (AVLIS). At a vaporization zone, many atomic collisions due to high density have influence on the atomic beam characteristics such as velocity distribution and metastable states' populations at a separation zone. In the separation zone, a symmetric charge transfer between the produced ions and the neutral atoms may degrade selectivity. We have measured atomic excitation temperatures of atomic beams and symmetric charge transfer cross sections for gadolinium and neodymium. Gadolinium and neodymium are both lanthanides. Nevertheless, results for gadolinium and neodymium are very different. The gadolinium atom has one 5d electron and neodymium atom has no 5d electron. It is considered that the differences are due to existence of 5d electron. (author)

Atomic charges of sulfur in ionic liquids: experiments and calculations.

Science.gov (United States)

Fogarty, Richard M; Rowe, Rebecca; Matthews, Richard P; Clough, Matthew T; Ashworth, Claire R; Brandt, Agnieszka; Corbett, Paul J; Palgrave, Robert G; Smith, Emily F; Bourne, Richard A; Chamberlain, Thomas W; Thompson, Paul B J; Hunt, Patricia A; Lovelock, Kevin R J

2017-12-14

Experimental near edge X-ray absorption fine structure (NEXAFS) spectra, X-ray photoelectron (XP) spectra and Auger electron spectra are reported for sulfur in ionic liquids (ILs) with a range of chemical structures. These values provide experimental measures of the atomic charge in each IL and enable the evaluation of the suitability of NEXAFS spectroscopy and XPS for probing the relative atomic charge of sulfur. In addition, we use Auger electron spectroscopy to show that when XPS binding energies differ by less than 0.5 eV, conclusions on atomic charge should be treated with caution. Our experimental data provides a benchmark for calculations of the atomic charge of sulfur obtained using different methods. Atomic charges were computed for lone ions and ion pairs, both in the gas phase (GP) and in a solvation model (SMD), with a wide range of ion pair conformers considered. Three methods were used to compute the atomic charges: charges from the electrostatic potential using a grid based method (ChelpG), natural bond orbital (NBO) population analysis and Bader's atoms in molecules (AIM) approach. By comparing the experimental and calculated measures of the atomic charge of sulfur, we provide an order for the sulfur atoms, ranging from the most negative to the most positive atomic charge. Furthermore, we show that both ChelpG and NBO are reasonable methods for calculating the atomic charge of sulfur in ILs, based on the agreement with both the XPS and NEXAFS spectroscopy results. However, the atomic charges of sulfur derived from ChelpG are found to display significant, non-physical conformational dependence. Only small differences in individual atomic charge of sulfur were observed between lone ion (GP) and ion pair IL(SMD) model systems, indicating that ion-ion interactions do not strongly influence individual atomic charges.

Local crystallography analysis for atomically resolved scanning tunneling microscopy images

International Nuclear Information System (INIS)

Lin, Wenzhi; Li, Qing; Belianinov, Alexei; Gai, Zheng; Baddorf, Arthur P; Pan, Minghu; Jesse, Stephen; Kalinin, Sergei V; Sales, Brian C; Sefat, Athena

2013-01-01

Scanning probe microscopy has emerged as a powerful and flexible tool for atomically resolved imaging of surface structures. However, due to the amount of information extracted, in many cases the interpretation of such data is limited to being qualitative and semi-quantitative in nature. At the same time, much can be learned from local atom parameters, such as distances and angles, that can be analyzed and interpreted as variations of local chemical bonding, or order parameter fields. Here, we demonstrate an iterative algorithm for indexing and determining atomic positions that allows the analysis of inhomogeneous surfaces. This approach is further illustrated by local crystallographic analysis of several real surfaces, including highly ordered pyrolytic graphite and an Fe-based superconductor FeTe 0.55 Se 0.45 . This study provides a new pathway to extract and quantify local properties for scanning probe microscopy images. (paper)

Quantum physics of entangled systems: wave-particle duality and atom-photon molecules

International Nuclear Information System (INIS)

Rempe, G.

2000-01-01

One of the cornerstones of quantum physics is the wave nature of matter. It explains experimentally observed effects like interference and diffraction, occurring when an object moves from one place to another along several indistinguishable ways simultaneously. The wave nature disappears when the individual ways are distinguishable. In this case, the particle nature of the object becomes visible. To determine the particle nature quantitatively, the way of the object has to be measured. Here, large progress has been made recently with new techniques, enabling one to investigate single moving atoms in a controlled manner. Two examples are discussed in the following two sections. The first experiment describes an atom interferometer, where the way of the atom is entangled with its internal state. This allows one to explore the origin of wave-particle duality and perform a quantitative test of this fundamental principle. The second experiment reports on the observation of an atom-photon molecule, a bound state between an atom and a single photon. A fascinating aspect of this system is that it makes possible to monitor the motion of a single neutral atom in real time. (orig.)

Superradiators created atom by atom

Science.gov (United States)

Meschede, Dieter

2018-02-01

High radiation rates are usually associated with macroscopic lasers. Laser radiation is “coherent”—its amplitude and phase are well-defined—but its generation requires energy inputs to overcome loss. Excited atoms spontaneously emit in a random and incoherent fashion, and for N such atoms, the emission rate simply increases as N. However, if these atoms are in close proximity and coherently coupled by a radiation field, this microscopic ensemble acts as a single emitter whose emission rate increases as N2 and becomes “superradiant,” to use Dicke's terminology (1). On page 662 of this issue, Kim et al. (2) show the buildup of coherent light fields through collective emission from atomic radiators injected one by one into a resonator field. There is only one atom ever in the cavity, but the emission is still collective and superradiant. These results suggest another route toward thresholdless lasing.

New sources of cold atoms for atomic clocks

International Nuclear Information System (INIS)

Aucouturier, E.

1997-01-01

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

Long-term outcomes of acute ischemic stroke patients treated with endovascular thrombectomy: A real-world experience.

Science.gov (United States)

Zhao, Wenbo; Shang, Shuyi; Li, Chuanhui; Wu, Longfei; Wu, Chuanjie; Chen, Jian; Song, Haiqing; Zhang, Hongqi; Zhang, Yunzhou; Duan, Jiangang; Feng, Wuwei; Ji, Xunming

2018-07-15

Long-term follow-up of large trials have confirmed the superiority of endovascular thrombectomy (ET) for treating acute ischemic stroke (AIS). However, it is still unknown whether these results can be generalized to clinical practice. In this study, we aimed to determine the long-term outcomes of AIS post-ET in the real-world clinical practice. This observational study is based on a single-center prospective registry study. AIS patients were treated with second-generation stent retrievers from December 2012 to April 2016. The primary outcome was modified Ranks scale (mRS) at the time of the latest assessment. Favorable outcome was defined as mRS scores 0-2, and the unfavorable outcome was defined as mRS scores 3-6. Eighty-nine AIS subjects with large artery occlusion in anterior circulation undergoing ET were eligible for analysis. Median follow-up duration was 20 months (interquartile range 6-32), and 47 subjects (53%) achieved favorable outcome whereas 17 subjects (19%) were functional dependence and 25 subjects (28%) died. Independent predicators for long-term unfavorable outcome were higher baseline National Institutes of Health Stroke Scale (NIHSS) score (odd ratio:1.21;95% confidence interval 1.09-1.35; p < 0.001) and symptomatic intracerebral hemorrhage (sICH) (odd ratio:16.45;95% confidence interval 1.34-193.44; p = 0.026). More subjects of large-artery-atherosclerosis underwent permanent intracranial stenting (22%vs.10%) as compared with those of cardioembolism, while subjects of cardioembolism were more likely to experience sICH (13%vs.8%) and died (32%vs.16%). Over half of AIS patients can achieve favorable long-term outcomes post-ET. Higher baseline NIHSS scores and sICH are independently associated with unfavorable outcome. Overall, clinical practice in this single canter can replicate the long-term outcomes from the published endovascular clinical trials. Copyright © 2018 Elsevier B.V. All rights reserved.

Expert system of real time for support of operators of atomic power plants

International Nuclear Information System (INIS)

Bashlykov, A.A.; Davidenko, N.N.; Dumshev, V.G.; Kislov, G.I.; Pavlova, E.V.; Prozorovskij, E.D.; Bashlykov, A.A.

1994-01-01

The problems of construction and introdution of an intellectual system for information support of operators at nuclear power plants are discussed. This system is used for operator assisstance during real time decision making for NPP operational regime control

Electron-atom collisions in a laser field

International Nuclear Information System (INIS)

Ehlotzky, F.

1998-01-01

The present work is a report on recent progress made in our understanding of electron-atom collisions in a laser field. To some extent it is a continuation of a previous review covering a somewhat larger subject (Can. J. Phys. 63 (1985)). We shall discuss the present status of investigations in this field from the theoretical as well as experimental point of view but most of the report will be devoted to an analysis of the various approximation schemes used at present in this field to describe the different aspects of laser-assisted electron-atom interactions. As the table of contents shows, most of the work done so far is treating the atom as a spectator, described by a potential and only very little has been achieved over the years to include the atomic structure into consideration since the inclusion of these structure effects poses considerable computational problems. Since, for example, multiphoton ionization and its inverse process laser-assisted recombination may be considered as one half of a scattering process, it is quite natural that some of the theoretical techniques described here are also of interest for the treatment of other multiphoton processes not considered here since there are several other recent reviews available on these topics. (orig.)

A simple analytical model for electronic conductance in a one dimensional atomic chain across a defect

International Nuclear Information System (INIS)

Khater, Antoine; Szczesniak, Dominik

2011-01-01

An analytical model is presented for the electronic conductance in a one dimensional atomic chain across an isolated defect. The model system consists of two semi infinite lead atomic chains with the defect atom making the junction between the two leads. The calculation is based on a linear combination of atomic orbitals in the tight-binding approximation, with a single atomic one s-like orbital chosen in the present case. The matching method is used to derive analytical expressions for the scattering cross sections for the reflection and transmission processes across the defect, in the Landauer-Buttiker representation. These analytical results verify the known limits for an infinite atomic chain with no defects. The model can be applied numerically for one dimensional atomic systems supported by appropriate templates. It is also of interest since it would help establish efficient procedures for ensemble averages over a field of impurity configurations in real physical systems.

Atom interferometry with trapped Bose-Einstein condensates: impact of atom-atom interactions

International Nuclear Information System (INIS)

Grond, Julian; Hohenester, Ulrich; Mazets, Igor; Schmiedmayer, Joerg

2010-01-01

Interferometry with ultracold atoms promises the possibility of ultraprecise and ultrasensitive measurements in many fields of physics, and is the basis of our most precise atomic clocks. Key to a high sensitivity is the possibility to achieve long measurement times and precise readout. Ultracold atoms can be precisely manipulated at the quantum level and can be held for very long times in traps; they would therefore be an ideal setting for interferometry. In this paper, we discuss how the nonlinearities from atom-atom interactions, on the one hand, allow us to efficiently produce squeezed states for enhanced readout and, on the other hand, result in phase diffusion that limits the phase accumulation time. We find that low-dimensional geometries are favorable, with two-dimensional (2D) settings giving the smallest contribution of phase diffusion caused by atom-atom interactions. Even for time sequences generated by optimal control, the achievable minimal detectable interaction energy ΔE min is of the order of 10 -4 μ, where μ is the chemical potential of the Bose-Einstein condensate (BEC) in the trap. From these we have to conclude that for more precise measurements with atom interferometers, more sophisticated strategies, or turning off the interaction-induced dephasing during the phase accumulation stage, will be necessary.

Atom-atom collision cascades localization

International Nuclear Information System (INIS)

Kirsanov, V.V.

1980-01-01

The presence of an impurity and thermal vibration influence on the atom-atom collision cascade development is analysed by the computer simulation method (the modificated dynamic model). It is discovered that the relatively low energetic cascades are localized with the temperature increase of an irradiated crystal. On the basis of the given effect the mechanism of splitting of the high energetic cascades into subcascades is proposed. It accounts for two factors: the primary knocked atom energy and the irradiated crystal temperature. Introduction of an impurity also localizes the cascades independently from the impurity atom mass. The cascades localization leads to intensification of the process of annealing in the cascades and reduction of the post-cascade vacancy cluster sizes. (author)

Code ATOM for calculation of atomic characteristics

International Nuclear Information System (INIS)

Vainshtein, L.A.

1990-01-01

In applying atomic physics to problems of plasma diagnostics, it is necessary to determine some atomic characteristics, including energies and transition probabilities, for very many atoms and ions. Development of general codes for calculation of many types of atomic characteristics has been based on general but comparatively simple approximate methods. The program ATOM represents an attempt at effective use of such a general code. This report gives a brief description of the methods used, and the possibilities of and limitations to the code are discussed. Characteristics of the following processes can be calculated by ATOM: radiative transitions between discrete levels, radiative ionization and recombination, collisional excitation and ionization by electron impact, collisional excitation and ionization by point heavy particle (Born approximation only), dielectronic recombination, and autoionization. ATOM explores Born (for z=1) or Coulomb-Born (for z>1) approximations. In both cases exchange and normalization can be included. (N.K.)

NATO Advanced Study Institute on Atoms in Strong Fields

CERN Document Server

Clark, Charles; Nayfeh, Munir

1990-01-01

This book collects the lectures given at the NATO Advanced Study Institute on "Atoms in Strong Fields", which took place on the island of Kos, Greece, during the two weeks of October 9-21,1988. The designation "strong field" applies here to an external electromagnetic field that is sufficiently strong to cause highly nonlinear alterations in atomic or molecular struc­ ture and dynamics. The specific topics treated in this volume fall into two general cater­ gories, which are those for which strong field effects can be studied in detail in terrestrial laboratories: the dynamics of excited states in static or quasi-static electric and magnetic fields; and the interaction of atoms and molecules with intense laser radiation. In both areas there exist promising opportunities for research of a fundamental nature. An electric field of even a few volts per centimeter can be very strong on the atom­ ic scale, if it acts upon a weakly bound state. The study of Rydberg states with high reso­ lution laser spectroscop...

Real-world treatment patterns and outcomes among metastatic cutaneous melanoma patients treated with ipilimumab.

Science.gov (United States)

Mohr, P; Ascierto, P; Arance, A; McArthur, G; Hernaez, A; Kaskel, P; Shinde, R; Stevinson, K

2018-06-01

There is a scarcity of real-world data on treatment patterns and outcomes among advanced melanoma patients treated with immunotherapies including ipilimumab, an anti-CTLA-4 antibody approved since 2011. To evaluate ipilimumab and postipilimumab treatment patterns and outcomes among patients with advanced melanoma in Australia, Germany, Italy and Spain, following regulatory approval. Retrospective multicentre, multinational, observational chart review study. Data were extracted from the start of ipilimumab therapy until the end of at least 40 weeks of follow-up, or death. Data from 371 patients (Australia, 103; Germany, 152; Italy, 76; Spain, 40) were analysed. Mean age was 65 years; 62% were male. Eastern Cooperative Oncology Group performance status (ECOG PS) was 0 or 1 for 94%. In 67%, ipilimumab was initially received as second-line or later therapy. Patients received on average 3.4 ipilimumab doses. The ipilimumab-refractory cohort comprised of 226 patients. Of these, 17% in Australia, 47% in Germany, 29% in Italy and 14% in Spain received another antimelanoma treatment after ipilimumab including chemotherapy in 26% and BRAF/other kinase inhibitors in 11%. Ipilimumab-refractory patients who received postipilimumab treatment showed a 40% reduced hazard of dying than those not receiving treatment after ipilimumab (HR 0.60; 95% CI 0.43-0.83), after adjustment for potential confounders. During the time observed, ipilimumab was mainly used as second-line or later therapy. A significant proportion of patients received postipilimumab therapy, most of which was chemotherapy. Nevertheless, overall survival following progression on ipilimumab treatment remained poor, highlighting the need for research to develop more effective end-of-life treatment options. © 2017 European Academy of Dermatology and Venereology.

STATUS OF RADIOACTIVE ELEMENTS IN THE ATOMIC WEIGHTS TABLE

International Nuclear Information System (INIS)

HOLDEN, N.E.

2003-01-01

During discussions within the Inorganic Chemistry Division Committee, that dealt with the Periodic Table of the Chemical Elements and the official IUPAC position on its presentation, the following question was raised. When the various chemical elements are presented, each with their appropriate atomic weight value, how should the radioactive elements be presented? The Atomic Weights Commission has treated this question in a number of different ways during the past century, almost in a random manner. This report reviews the position that the Commission has taken as a function of time, as a prelude to a discussion in Ottawa about how the Commission should resolve this question for the future

Atomic physics

International Nuclear Information System (INIS)

Armbruster, P.; Beyer, H.; Bosch, F.; Dohmann, H.D.; Kozhuharov, C.; Liesen, D.; Mann, R.; Mokler, P.H.

1984-01-01

The heavy ion accelerator UNILAC is well suited to experiments in the field of atomic physics because, with the aid of high-energy heavy ions atoms can be produced in exotic states - that is, heavy atoms with only a few electrons. Also, in close collisions of heavy ions (atomic number Z 1 ) and heavy target atoms (Z 2 ) short-lived quasi-atomic 'superheavy' systems will be formed - huge 'atoms', where the inner electrons are bound in the field of the combined charge Z 1 + Z 2 , which exceeds by far the charge of the known elements (Z <= 109). Those exotic or transient superheavy atoms delivered from the heavy ion accelerator make it possible to study for the first time in a terrestrial laboratory exotic, but fundamental, processes, which occur only inside stars. Some of the basic research carried out with the UNILAC is discussed. This includes investigation of highly charged heavy atoms with the beam-foil method, the spectroscopy of highly charged slow-recoil ions, atomic collision studies with highly ionised, decelerated ions and investigations of super-heavy quasi-atoms. (U.K.)

Wireless Sensor Network Metrics for Real-Time Systems

Science.gov (United States)

2009-05-20

Wireless Sensor Network Metrics for Real-Time Systems Phoebus Wei-Chih Chen Electrical Engineering and Computer Sciences University of California at...3. DATES COVERED 00-00-2009 to 00-00-2009 4. TITLE AND SUBTITLE Wireless Sensor Network Metrics for Real-Time Systems 5a. CONTRACT NUMBER 5b... wireless sensor networks (WSNs) is moving from studies of WSNs in isolation toward studies where the WSN is treated as a component of a larger system

Atomic Quantum Simulations of Abelian and non-Abelian Gauge Theories

CERN Multimedia

CERN. Geneva

2014-01-01

Using a Fermi-Bose mixture of ultra-cold atoms in an optical lattice, in a collaboration of atomic and particle physicists, we have constructed a quantum simulator for a U(1) gauge theory coupled to fermionic matter. The construction is based on quantum link models which realize continuous gauge symmetry with discrete quantum variables. At low energies, quantum link models with staggered fermions emerge from a Hubbard-type model which can be quantum simulated. This allows investigations of string breaking as well as the real-time evolution after a quench in gauge theories, which are inaccessible to classical simulation methods. Similarly, using ultracold alkaline-earth atoms in optical lattices, we have constructed a quantum simulator for U(N) and SU(N) lattice gauge theories with fermionic matter based on quantum link models. These systems share qualitative features with QCD, including chiral symmetry breaking and restoration at non-zero temperature or baryon density. Unlike classical simulations, a quantum ...

Coupled-channels calculations of excitation and ionization in ion-atom collisions

International Nuclear Information System (INIS)

Martir, M.H.

1981-01-01

A numerical method has been used to compute excitation and ionization cross sections for ion-atom collisions. The projectile is treated classically and follows a straight line, constant velocity path (unless indicated otherwise). The wave function that describes the atom is expanded about the target in a truncated Hilbert space. The interaction between the projectile and the target atom is treated as a time dependent perturbation. A unitary time development operator, U, propagates the wave function from a time prior to the collision to a time after the collision in small time steps. Contrary to first-order theories, coupling between states is allowed. This method has been improved so that any number of partial waves can be included in the wave function expansion. This method has been applied to study negatively charged projectiles. Cross sections are obtained for collisions of antiprotons on atomic hydrogen (30 keV to 372 keV) and compared with cross sections of protons on atomic hydrogen to explore the Z/sub P/ dependence. The antiproton-hydrogen results were converted into electron-hydrogen values with E/sub e/ = E/sub P/(m/sub e//m/sub P/) (15 eV to 200 eV) and compared to experimental values. The method is then applied to study vacancy production from the L-shell. The partial wave convergence of the cross sections was carefully studied for s through g waves. Collisions between protons (and alpha-particles) and argon are studied to explore the Z/sub P/ dependence of the cross sections. The cross section ratio sigma(α)/(4sigma(p)) is compared to experiment

Ionization of atoms by high energy photons

International Nuclear Information System (INIS)

Amusia, M.Y.; Ioffe, A.F.

1994-01-01

Photoionization of atoms by high energy photons is considered. It is emphasized that in this frequency region the cross section and other characteristics of the process are strongly effected by electron shell polarization and rearrangement effects, including that due to inner vacancy Auger decay. In the effects of nuclear structure could be important and noticeable, i.e. of virtual or real excitation of the nucleus degrees of freedom and of the Quantum Electrodynamics vacuum. Ionization accompanied by secondary photon emission (Compton ionization) is analyzed in the considered domain of energies

Atom optics

International Nuclear Information System (INIS)

Balykin, V. I.; Jhe, W.

1999-01-01

Atom optics, in analogy to neutron and electron optics, deals with the realization of as a traditional elements, such as lenes, mirrors, beam splitters and atom interferometers, as well as a new 'dissipative' elements such as a slower and a cooler, which have no analogy in an another types of optics. Atom optics made the development of atom interferometer with high sensitivity for measurement of acceleration and rotational possible. The practical interest in atom optics lies in the opportunities to create atom microprobe with atom-size resolution and minimum damage of investigated objects. (Cho, G. S.)

Modified dynamic Stark shift and depopulation rate of an atom inside a Kerr nonlinear blackbody

International Nuclear Information System (INIS)

Yin Miao; Cheng Ze

2009-01-01

We investigate the dynamic Stark shift and atomic depopulation rate induced by real photons in a Kerr nonlinear blackbody. We found that the dynamic Stark shift and atomic depopulation rate are equally modified by a nonlinear contribution factor and a linear contribution factor under a transition temperature T c . The nonlinear contribution factor depends on the Kerr nonlinear coefficient as well as the absolute temperature. Below T c , the absolute values of the dynamic Stark shift and depopulation rate of a single atomic state (not the ground state) are correspondingly larger than those in a normal blackbody whose interior is filled with a nonabsorbing linear medium. Above T c , the dynamic Stark shift and atomic depopulation rate are correspondingly equal to those in a normal blackbody with a nonabsorbing linear medium in its interior.

A Hartree–Fock study of the confined helium atom: Local and global basis set approaches

Energy Technology Data Exchange (ETDEWEB)

Young, Toby D., E-mail: tyoung@ippt.pan.pl [Zakład Metod Komputerowych, Instytut Podstawowych Prolemów Techniki Polskiej Akademia Nauk, ul. Pawińskiego 5b, 02-106 Warszawa (Poland); Vargas, Rubicelia [Universidad Autónoma Metropolitana Iztapalapa, División de Ciencias Básicas e Ingenierías, Departamento de Química, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, D.F. C.P. 09340, México (Mexico); Garza, Jorge, E-mail: jgo@xanum.uam.mx [Universidad Autónoma Metropolitana Iztapalapa, División de Ciencias Básicas e Ingenierías, Departamento de Química, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, D.F. C.P. 09340, México (Mexico)

2016-02-15

Two different basis set methods are used to calculate atomic energy within Hartree–Fock theory. The first is a local basis set approach using high-order real-space finite elements and the second is a global basis set approach using modified Slater-type orbitals. These two approaches are applied to the confined helium atom and are compared by calculating one- and two-electron contributions to the total energy. As a measure of the quality of the electron density, the cusp condition is analyzed. - Highlights: • Two different basis set methods for atomic Hartree–Fock theory. • Galerkin finite element method and modified Slater-type orbitals. • Confined atom model (helium) under small-to-extreme confinement radii. • Detailed analysis of the electron wave-function and the cusp condition.

The Real Options Attached to an Investment Project

Directory of Open Access Journals (Sweden)

Mihai-Cristian DINICĂ

2011-12-01

Full Text Available The real options capture the importance of the managerial team’s role in creating value through investment projects. The investments in real assets have a set of options that managers can exercise during the period of the project to increase the value of the assets or to limit the eventual losses. This options have their own value.The traditional methods for investment project evaluatioan, based on discounted cash flows, have some major disadvantages: they assume the irreversibility of a decision, do not take into account the interactions between decisions in several periods and treat the investment as pasive. The evaluation using real options undertake this disadvantage. The paper shows the main types of real options, together with their elements and captures the impact of these options on the value of the investment. The main two models used to evaluate real options, the binomial model and Black-Scholes model, are explained and used to compute the value of real options attached to an investment project.

Dispersion interaction between an atom and linear molecule

International Nuclear Information System (INIS)

Carvalho, I.L. de

1987-01-01

The Jacobi-Csanak method is adapted to the calculation of the dipole-dipole, dipole-quadrupole, quadrupole-dipole, and quadrupole-quadrupole terms of the dispersion energy of an atom-linear molecule system. The angle-dependent parts of the Born amplitudes for the linear molecule are represented by real spherical harmonics. The dispersion energy is finite at all distances and reproduces the usual expression in the asymptotic region (R≥4.7 (angstrom)). In the intermediary region (2.4(angstrom) ≤ R [pt

Atomic weight versus atomic mass controversy

International Nuclear Information System (INIS)

Holden, N.E.

1985-01-01

A problem for the Atomic Weights Commission for the past decade has been the controversial battle over the names ''atomic weight'' and ''atomic mass''. The Commission has considered the arguments on both sides over the years and it appears that this meeting will see more of the same discussion taking place. In this paper, I review the situation and offer some alternatives

Fluorescence detection of white-beam X-ray absorption anisotropy: towards element-sensitive projections of local atomic structure

Science.gov (United States)

Korecki, P.; Tolkiehn, M.; Dąbrowski, K. M.; Novikov, D. V.

2011-01-01

Projections of the atomic structure around Nb atoms in a LiNbO3 single crystal were obtained from a white-beam X-ray absorption anisotropy (XAA) pattern detected using Nb K fluorescence. This kind of anisotropy results from the interference of X-rays inside a sample and, owing to the short coherence length of a white beam, is visible only at small angles around interatomic directions. Consequently, the main features of the recorded XAA corresponded to distorted real-space projections of dense-packed atomic planes and atomic rows. A quantitative analysis of XAA was carried out using a wavelet transform and allowed well resolved projections of Nb atoms to be obtained up to distances of 10 Å. The signal of nearest O atoms was detected indirectly by a comparison with model calculations. The measurement of white-beam XAA using characteristic radiation indicates the possibility of obtaining element-sensitive projections of the local atomic structure in more complex samples. PMID:21997909

On the deviation from the sech2 superradiant emission law in a two-level atomic system

International Nuclear Information System (INIS)

Goncalves, A.E.

1990-01-01

The atomic superradiant emission is treated in the single particle mean field approximation. A single particle Hamiltonian, which represents a dressed two-level atom in a radiation field, can be obtained and it is verified that it describes the transient regime of the emission process. While the line shape emission for a bare atom follows the sech 2 law, for the dressed atom the line shape deviates appreciably from this law and it is verified that the deviation depends crucially on the ratio of the dynamic frequency shift to the transition frequency. This kind of deviation is observed in experimental results. (Author) [pt

Electronic spectral properties of surfaces and adsorbates and atom-adsorbate van der Waals interactions

International Nuclear Information System (INIS)

Lovric, D.; Gumhalter, B.

1988-01-01

The relevance of van der Waals interactions in the scattering of neutral atoms from adsorbates has been recently confirmed by highly sensitive molecular-beam techniques. The theoretical descriptions of the collision dynamics which followed the experimental studies have necessitated very careful qualitative and quantitative examinations and evaluations of the properties of atom-adsorbate van der Waals interactions for specific systems. In this work we present a microscopic calculation of the strengths and reference-plane positions for van der Waals potentials relevant for scattering of He atoms from CO adsorbed on various metallic substrates. In order to take into account the specificities of the polarization properties of real metals (noble and transition metals) and of chemisorbed CO, we first calculate the spectra of the electronic excitations characteristic of the respective electronic subsystems by using various data sources available and combine them with the existing theoretical models. The reliability of the calculated spectra is then verified in each particular case by universal sum rules which may be established for the electronic excitations of surfaces and adsorbates. The substrate and adsorbate polarization properties which derive from these calculations serve as input data for the evaluation of the strengths and reference-plane positions of van der Waals potentials whose computed values are tabulated for a number of real chemisorption systems. The implications of the obtained results are discussed in regard to the atom-adsorbate scattering cross sections pertinent to molecular-beam scattering experiments

Lattice and strain analysis of atomic resolution Z-contrast images based on template matching

Energy Technology Data Exchange (ETDEWEB)

Zuo, Jian-Min, E-mail: jianzuo@uiuc.edu [Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801 (United States); Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801 (United States); Shah, Amish B. [Center for Microanalysis of Materials, Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Kim, Honggyu; Meng, Yifei; Gao, Wenpei [Department of Materials Science and Engineering, University of Illinois, Urbana, IL 61801 (United States); Seitz Materials Research Laboratory, University of Illinois, Urbana, IL 61801 (United States); Rouviére, Jean-Luc [CEA-INAC/UJF-Grenoble UMR-E, SP2M, LEMMA, Minatec, Grenoble 38054 (France)

2014-01-15

A real space approach is developed based on template matching for quantitative lattice analysis using atomic resolution Z-contrast images. The method, called TeMA, uses the template of an atomic column, or a group of atomic columns, to transform the image into a lattice of correlation peaks. This is helped by using a local intensity adjusted correlation and by the design of templates. Lattice analysis is performed on the correlation peaks. A reference lattice is used to correct for scan noise and scan distortions in the recorded images. Using these methods, we demonstrate that a precision of few picometers is achievable in lattice measurement using aberration corrected Z-contrast images. For application, we apply the methods to strain analysis of a molecular beam epitaxy (MBE) grown LaMnO{sub 3} and SrMnO{sub 3} superlattice. The results show alternating epitaxial strain inside the superlattice and its variations across interfaces at the spatial resolution of a single perovskite unit cell. Our methods are general, model free and provide high spatial resolution for lattice analysis. - Highlights: • A real space approach is developed for strain analysis using atomic resolution Z-contrast images and template matching. • A precision of few picometers is achievable in the measurement of lattice displacements. • The spatial resolution of a single perovskite unit cell is demonstrated for a LaMnO{sub 3} and SrMnO{sub 3} superlattice grown by MBE.

Angular momentum coupling in atom-atom collisions

International Nuclear Information System (INIS)

Grosser, J.

1986-01-01

The coupling between the electronic angular momentum and the rotating atom-atom axis in the initial or the final phase of an atom-atom collision is discussed, making use of the concepts of radial and rotational (Coriolis) coupling between different molecular states. The description is based on a limited number of well-understood approximations, and it allows an illustrative geometric representation of the transition from the body fixed to the space fixed motion of the electrons. (orig.)

Reconstruction of a cold atom cloud by magnetic focusing

International Nuclear Information System (INIS)

Saba, C.V.

1999-12-01

Over the passed 15 years advances in laser cooling techniques have made it routinely possible to prepare cold clouds of atoms exhibiting temperatures of the order of several micro-Kelvin or less. Such low temperatures correspond to average atomic velocities of a few centimetres per second. Therefore, according to the de Broglie relationship p = h/λ, the atoms increasingly exhibit wave-like behaviour and can no longer be treated solely as particles. These advances in atom manipulation have renewed interest in the field of atom optics. One of the concerns of atom optics is the manipulation of atoms with optical elements analogous to those used in photon optics. The most basic of such elements is the mirror. This thesis presents a curved mirror for paramagnetic atoms fabricated from commercial video tape. It is the smoothest magnetic mirror to date and is the third generation of mirrors fabricated by our group using magnetic recording media. Previous designs used audio tape and 5 1/4 inch floppy disk. Using fluorescence imaging we have directly imaged atoms bouncing above the mirror and, owing to its smoothness, have observed the first ever reconstruction of a cold atom cloud above a curved reflector. The atoms were collected in a magneto optical trap (MOT), cooled to a temperature of 18 μK and then dropped onto the mirror. When released from a height of 13.5 mm we observed the collimation and refocusing of the cloud on consecutive bounces. Furthermore, we observed up to 14 bounces of the cloud, which corresponds to a time of ∼1.5 s. One of the factors that limited the number of observable bounces was the presence of some finite roughness in the reflecting surface. Using images of the focused cloud at the peak of even bounces we were able to measure this roughness and found it to be 5.9 mrads. By analysing magnetic force microscope (MFM) scans of the fields above the mirror we attributed this residual roughness to the spatial inhomogeneity of magnetic particles in

Anomalies in resonant absorption line profiles of atoms with large hyperfine splitting

International Nuclear Information System (INIS)

Parkhomenko, A.I.; Pod'yachev, S.P.; Privalov, T.I.; Shalagin, A.M.

1997-01-01

We examine a monochromatic absorption line in the velocity-nonselective excitation of atoms when the components of the hyperfine stricture of the electronic ground states are optically pumped. We show that the absorption lines possess unusual substructures for some values of the hyperfine splitting of the ground state (which exceed the Doppler absorption linewidth severalfold). These substructures in the absorption spectrum are most apparent if the hyperfine structure of the excited electronic state is taken into account. We calculate the absorption spectra of monochromatic light near the D 1 and D 2 lines of atomic rubidium 85,87 Rb. With real hyperfine splitting taken into account, the D 1 and D 2 lines are modeled by 4- and 6-level diagrams, respectively. Finally, we show that atomic rubidium vapor can be successfully used to observe the spectral features experimentally

Cleaning of Fire Damaged Watercolor and Textiles Using Atomic Oxygen

Science.gov (United States)

Rutledge, Sharon K.; Banks, Bruce A.; Chichernea, Virgil A.; Haytas, Christy A.

2000-01-01

A noncontact technique is described that uses atomic oxygen generated under low pressure in the presence of nitrogen to remove soot from the surface of a test watercolor panel and strips of cotton, wool and silk. The process, which involves surface oxidation, permits control of the amount of surface material removed. The effectiveness of soot removal from test panels of six basic watercolors (alizarin crimson, burnt sienna, lemon yellow, yellow ochre, cerulean blue and ultramarine blue) and strips of colored cotton, wool and silk was measured using reflectance spectroscopy. The atomic oxygen removed soot effectively from the treated areas and enabled partial recovery of charred watercolors. However, overexposure can result in removal of sizing, bleaching, and weakening of the structure. With the proper precautions, atomic oxygen treatment appears to have great potential to salvage heavily smoke damaged artworks which were previously considered unrestorable.

Ultrafast Processes in Atoms and Molecules: Integrated treatment of electronic and nuclear motion in ultrashort XUV pulses

Energy Technology Data Exchange (ETDEWEB)

McCurdy, C. William [Univ. of California, Davis, CA (United States). Dept. of

2017-12-14

This project made use of Multiconfiguration Time-Dependent Hartree-Fock method developed earlier in the McCurdy group in a series of novel applications of the method to ultrafast spectroscopic processes. MCTDHF treats the dynamics of a molecule or atom under the influence of an external field in manner that has all electrons active. That property distinguishes this method from the more popular (and much less computationally demanding) approaches for treating the electron dynamics of atoms and molecules in fields, such as the time-dependent “Configuration Interaction Singles” approximation or approaches that limit the treatment to either one or two-electron models.

The detection of cold antihydrogen atoms

International Nuclear Information System (INIS)

Zhang, Zhongdong

2007-01-01

The ATRAP experiment at CERN's antiproton decelerator (AD) aims for a test of CPT violation and Lorentz invariance by a comparison of hydrogen to antihydrogen atom spectroscopy and a measurement of the gravitational force on antimatter atoms. The experiment is divided into two parts: ATRAP-I, where successfully antihydrogen atoms were produced and intensive studies on the charged clouds of positrons and antiprotons were performed, and ATRAP-II which was commissioned during the beam-time 2006. ATRAP-II includes a much larger superconducting solenoid bore allowing the installation of an extended detection system as well as an optimized combined Penning-Ioffe trap. Another essential part is a new positron accumulator and delivery system which will increase the ATRAP-II efficiency drastically. Thus ATRAP-II now allows for much larger flexibility, increased performance, higher robustness, and better efficiency for the production and storage of cold antihydrogen atoms. A general overview of the experimental setup for the second phase of the ATRAP experiment will be presented in this thesis. The antiproton annihilation detector system, consisting of several layers of scintillating fibers, counts the antihydrogen atoms and determines the annihilation vertex of the atoms. This diagnostic element will allow to optimize the production of cold antihydrogen sufficiently to permit optical observations and measurements. Extensive Monte Carlo simulations concerning the track fitting and vertex reconstruction have been developed during the planned interruption of antiproton production at AD in the year 2005. Different event generators, magnetic field distributions as well as data reconstruction algorithms on simulated data were established and the results were compared to data in 2006. To improve the detector position resolution, a constraint-fit procedure was adopted. Further possible improvements, by applying certain cuts on the data, were investigated. Real-time measurements

Cascade of negative muons in atoms

International Nuclear Information System (INIS)

Akylas, V.R.

1978-01-01

A study is made of the evolution of a negative muon captured in an atom and the formalism of energy loss associated with the muonic atom. The principal goals are to calculate reliability the muon x-ray intensities, given the initial population of the muonic orbits, to invert the problem and deduce the initial distribution from the x-ray intensities, to provide a reasonably simple and convenient tool to correlate observations, and finally, to systematize some questions of theoretical interest. The early part of the history of the muon in matter, including the atomic capture and classical phase of the atomic cascade are reviewed. In the quantal treatment of the transition rates, both radiative and electron Auger transitions are considered. In general, multipolarities up to E3 and K, L, and M electronic shells are fully investigated. Multipole radiation is treated in the conventinal way and pesents no special problems. Magnetic type transitions between states with different principal quantum numbers are shown to be small. Auger electron ejection rates are more complicated and several approximations have been adopted. The basic results have been computed in terms of elemetary functions. In the Auger transitions we have shown that magnetic multipoles can be safety neglected. The relative sizes of the rates corresponding to different multipoles are systematically studied. A comparison of results is made with atomic photoelectric effect data and with the nuclear internal conversion coefficients. A general agreement is found, except around shell thresholds. The existing data of muonic x-ray intensities in iron and thallium are analyzed in a systematic way. It is found that for Fe the initial l-distribution is almost flat, whereas that for T1 is weighted towards the high l values, sharper than statistical. As a result of the investigations and in order to make our findings usable, a computer program has been developed. 36 references

Study on the application of electrothermal atomization atomic absorption spectrometry for the determination of metallic Cu, Pb, Zn, Cd traces in sea water samples

International Nuclear Information System (INIS)

Nguyen Thi Kim Dung; Doan Thanh Son; Tran Thi Ngoc Diep

2004-01-01

The trace amount of some heavy metallic elements (Cu, Zn, Pb, Cd) in sea water samples were determined directly (without separation) and quantitatively by using Electro-Thermal Atomization Atomic Absorption Spectrometry (ETA-AAS). The effect of mainly major constituents such as Na, Mg, Ca, K, and the mutual effect of the trace elements, which were present in the matrix on the absorption intensity of each analyzed element was studied. The adding of a certain chemical modification for each trace element was also investigated in order to eliminate the overall effect of the background during the pyrolysis and atomization. The sea water sample after fitrating through a membrane with 0.45 μm-hole size was injected in to the graphite tube via an autosampler (MPE50). The absorption intensity of each element was then measured on the VARIO-6 under the optimum parameters for spectrometer such as: maximum wavelength, current of hollow cathode lamp, and that for graphite furnace such as dry temperature, pyrolysis temperature, atomization temperature, ect. The analytical procedures were set-up and applied for the determination of these above mentioned elements in the synthesized sea water sample and in the real sea water samples with high precision and accuracy. (author)

Sub-Angstrom Atomic-Resolution Imaging of Heavy Atoms to Light Atoms

Energy Technology Data Exchange (ETDEWEB)

O' Keefe, Michael A.; Shao-Horn, Yang

2003-05-23

Three decades ago John Cowley and his group at ASU achieved high-resolution electron microscope images showing the crystal unit cell contents at better than 4Angstrom resolution. Over the years, this achievement has inspired improvements in resolution that have enabled researchers to pinpoint the positions of heavy atom columns within the cell. More recently, this ability has been extended to light atoms as resolution has improved. Sub-Angstrom resolution has enabled researchers to image the columns of light atoms (carbon, oxygen and nitrogen) that are present in many complex structures. By using sub-Angstrom focal-series reconstruction of the specimen exit surface wave to image columns of cobalt, oxygen, and lithium atoms in a transition metal oxide structure commonly used as positive electrodes in lithium rechargeable batteries, we show that the range of detectable light atoms extends to lithium. HRTEM at sub-Angstrom resolution will provide the essential role of experimental verification for the emergent nanotech revolution. Our results foreshadow those to be expected from next-generation TEMs with Cs-corrected lenses and monochromated electron beams.

The quantum beat principles and applications of atomic clocks

CERN Document Server

Major, F

2007-01-01

This work attempts to convey a broad understanding of the physical principles underlying the workings of these quantum-based atomic clocks, with introductory chapters placing them in context with the early development of mechanical clocks and the introduction of electronic time-keeping as embodied in the quartz-controlled clocks. While the book makes no pretense at being a history of atomic clocks, it nevertheless takes a historical perspective in its treatment of the subject. Intended for nonspecialists with some knowledge of physics or engineering, The Quantum Beat covers a wide range of salient topics relevant to atomic clocks, treated in a broad intuitive manner with a minimum of mathematical formalism. Detailed descriptions are given of the design principles of the rubidium, cesium, hydrogen maser, and mercury ion standards; the revolutionary changes that the advent of the laser has made possible, such as laser cooling, optical pumping, the formation of "optical molasses," and the cesium "fountain" stand...

Atomic absorption spectrometry using tungsten and molybdenum tubes as metal atomizer

International Nuclear Information System (INIS)

Kaneco, Satoshi; Katsumata, Hideyuki; Ohta, Kiyohisa; Suzuki, Tohru

2007-01-01

We have developed a metal tube atomizer for the electrothermal atomization atomic absorption spectrometry (ETA-AAS). Tungsten, molybdenum, platinum tube atomizers were used as the metal atomizer for ETA-AAS. The atomization characteristics of various metals using these metal tube atomizers were investigated. The effects of heating rate of atomizer, atomization temperature, pyrolysis temperature, argon purge gas flow rate and hydrogen addition on the atomic absorption signal were investigated for the evaluation of atomization characteristics. Moreover, ETA-AAS with metal tube atomizer has been combined with the slurry-sampling techniques. Ultrasonic slurry-sampling ETA-AAS with metal tube atomizer were effective for the determination of trace metal elements in biological materials, calcium drug samples, herbal medicine samples, vegetable samples and fish samples. Furthermore, a preconcentration method of trace metals involving adsorption on a metal wire has been applied to ETA-AAS with metal tube atomizer. (author)

Theoretical femtosecond physics atoms and molecules in strong laser fields

CERN Document Server

Grossmann, Frank

2018-01-01

This textbook extends from the basics of femtosecond physics all the way to some of the latest developments in the field. In this updated edition, the chapter on laser-driven atoms is augmented by the discussion of two-electron atoms interacting with strong and short laser pulses, as well as by a review of ATI rings and low energy structures in photo-electron spectra. In the chapter on laser-driven molecules a discussion of 2D infrared spectroscopy is incorporated. Theoretical investigations of atoms and molecules interacting with pulsed lasers up to atomic field strengths on the order of 10^16 W/cm² are leading to an understanding of many challenging experimental discoveries. The presentation starts with a brief introduction to pulsed laser physics. The basis for the non-perturbative treatment of laser-matter interaction in the book is the time-dependent Schrödinger equation. Its analytical as well as numerical solution are laid out in some detail. The light field is treated classically and different possi...

Effective Inertial Frame in an Atom Interferometric Test of the Equivalence Principle

Science.gov (United States)

Overstreet, Chris; Asenbaum, Peter; Kovachy, Tim; Notermans, Remy; Hogan, Jason M.; Kasevich, Mark A.

2018-05-01

In an ideal test of the equivalence principle, the test masses fall in a common inertial frame. A real experiment is affected by gravity gradients, which introduce systematic errors by coupling to initial kinematic differences between the test masses. Here we demonstrate a method that reduces the sensitivity of a dual-species atom interferometer to initial kinematics by using a frequency shift of the mirror pulse to create an effective inertial frame for both atomic species. Using this method, we suppress the gravity-gradient-induced dependence of the differential phase on initial kinematic differences by 2 orders of magnitude and precisely measure these differences. We realize a relative precision of Δ g /g ≈6 ×10-11 per shot, which improves on the best previous result for a dual-species atom interferometer by more than 3 orders of magnitude. By reducing gravity gradient systematic errors to one part in 1 013 , these results pave the way for an atomic test of the equivalence principle at an accuracy comparable with state-of-the-art classical tests.

Atom chips: mesoscopic physics with cold atoms

International Nuclear Information System (INIS)

Krueger, P.; Wildermuth, S.; Hofferberth, S.; Haller, E.; GAllego Garcia, D.; Schmiedmayer, J.

2005-01-01

Full text: Cold neutral atoms can be controlled and manipulated in microscopic potentials near surfaces of atom chips. These integrated micro-devices combine the known techniques of atom optics with the capabilities of well established micro- and nanofabrication technology. In analogy to electronic microchips and integrated fiber optics, the concept of atom chips is suitable to explore the domain of mesoscopic physics with matter waves. We use current and charge carrying structures to form complex potentials with high spatial resolution only microns from the surface. In particular, atoms can be confined to an essentially one-dimensional motion. In this talk, we will give an overview of our experiments studying the manipulation of both thermal atoms and BECs on atom chips. First experiments in the quasi one-dimensional regime will be presented. These experiments profit from strongly reduced residual disorder potentials caused by imperfections of the chip fabrication with respect to previously published experiments. This is due to our purely lithographic fabrication technique that proves to be advantageous over electroplating. We have used one dimensionally confined BECs as an ultra-sensitive probe to characterize these potentials. These smooth potentials allow us to explore various aspects of the physics of degenerate quantum gases in low dimensions. (author)

Absorption imaging of ultracold atoms on atom chips

DEFF Research Database (Denmark)

Smith, David A.; Aigner, Simon; Hofferberth, Sebastian

2011-01-01

Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present...... methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions....

Observing electron localization in a dissociating H2+ molecule in real time.

Science.gov (United States)

Xu, H; Li, Zhichao; He, Feng; Wang, X; Atia-Tul-Noor, A; Kielpinski, D; Sang, R T; Litvinyuk, I V

2017-06-16

Dissociation of diatomic molecules with odd number of electrons always causes the unpaired electron to localize on one of the two resulting atomic fragments. In the simplest diatomic molecule H 2 + dissociation yields a hydrogen atom and a proton with the sole electron ending up on one of the two nuclei. That is equivalent to breaking of a chemical bond-the most fundamental chemical process. Here we observe such electron localization in real time by performing a pump-probe experiment. We demonstrate that in H 2 + electron localization is complete in just 15 fs when the molecule's internuclear distance reaches 8 atomic units. The measurement is supported by a theoretical simulation based on numerical solution of the time-dependent Schrödinger equation. This observation advances our understanding of detailed dynamics of molecular dissociation.

DelPhi web server v2: incorporating atomic-style geometrical figures into the computational protocol.

Science.gov (United States)

Smith, Nicholas; Witham, Shawn; Sarkar, Subhra; Zhang, Jie; Li, Lin; Li, Chuan; Alexov, Emil

2012-06-15

A new edition of the DelPhi web server, DelPhi web server v2, is released to include atomic presentation of geometrical figures. These geometrical objects can be used to model nano-size objects together with real biological macromolecules. The position and size of the object can be manipulated by the user in real time until desired results are achieved. The server fixes structural defects, adds hydrogen atoms and calculates electrostatic energies and the corresponding electrostatic potential and ionic distributions. The web server follows a client-server architecture built on PHP and HTML and utilizes DelPhi software. The computation is carried out on supercomputer cluster and results are given back to the user via http protocol, including the ability to visualize the structure and corresponding electrostatic potential via Jmol implementation. The DelPhi web server is available from http://compbio.clemson.edu/delphi_webserver.

Role of atom--atom inelastic collisions in two-temperature nonequilibrium plasmas

International Nuclear Information System (INIS)

Kunc, J.A.

1987-01-01

The contribution of inelastic atom--atom collisions to the production of electrons and excited atoms in two-temperature (with electron temperature T/sub e/, atomic temperature T/sub a/, and atomic density N/sub a/), steady-state, nonequilibrium atomic hydrogen plasma is investigated. The results are valid for plasmas having large amounts of atomic hydrogen as one of the plasma components, so that e--H and H--H inelastic collisions and interaction of these atoms with radiation dominate the production of electrons and excited hydrogen atoms. Densities of electrons and excited atoms are calculated in low-temperature plasma, with T/sub e/ and T/sub a/≤8000 K and 10 16 cm -3 ≤N/sub a/≤10 18 cm -3 , and with different degrees of the reabsorption of radiation. The results indicate that inelastic atom--atom collisions are important for production of electrons and excited atoms in partially ionized plasmas with medium and high atomic density and temperatures below 8000 K

Real-Time Wait-Free Queues using Micro-Transactions

OpenAIRE

Meawad, Fadi; Iyer, Karthik; Schoeberl, Martin; Vitek, Jan

2011-01-01

This paper evaluates the applicability of transactional mem- ory to the implementation of dierent non-blocking data structures in the context of the Real-time Specication for Java. In particular, we argue that hardware support for micro-transaction allows us to implement eciently data structures that are often dicult to realize with the atomic operations provided by stock hardware. Our main imple- mentation platform is the Java Optimized Processor sys- tem. We report on the performance of dat...

A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms.

Science.gov (United States)

Huo, Ming-Xia; Nie, Wei; Hutchinson, David A W; Kwek, Leong Chuan

2014-08-08

Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a "hairline" solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

A solenoidal synthetic field and the non-Abelian Aharonov-Bohm effects in neutral atoms

Science.gov (United States)

Huo, Ming-Xia; Nie, Wei; Hutchinson, David A. W.; Kwek, Leong Chuan

2014-08-01

Cold neutral atoms provide a versatile and controllable platform for emulating various quantum systems. Despite efforts to develop artificial gauge fields in these systems, realizing a unique ideal-solenoid-shaped magnetic field within the quantum domain in any real-world physical system remains elusive. Here we propose a scheme to generate a ``hairline'' solenoid with an extremely small size around 1 micrometer which is smaller than the typical coherence length in cold atoms. Correspondingly, interference effects will play a role in transport. Despite the small size, the magnetic flux imposed on the atoms is very large thanks to the very strong field generated inside the solenoid. By arranging different sets of Laguerre-Gauss (LG) lasers, the generation of Abelian and non-Abelian SU(2) lattice gauge fields is proposed for neutral atoms in ring- and square-shaped optical lattices. As an application, interference patterns of the magnetic type-I Aharonov-Bohm (AB) effect are obtained by evolving atoms along a circle over several tens of lattice cells. During the evolution, the quantum coherence is maintained and the atoms are exposed to a large magnetic flux. The scheme requires only standard optical access, and is robust to weak particle interactions.

Nonequilibrium forces between atoms and dielectrics mediated by a quantum field

International Nuclear Information System (INIS)

Behunin, Ryan O.; Hu, Bei-Lok

2011-01-01

In this paper we give a first principles microphysics derivation of the nonequilibrium forces between an atom, treated as a three-dimensional harmonic oscillator, and a bulk dielectric medium modeled as a continuous lattice of oscillators coupled to a reservoir. We assume no direct interaction between the atom and the medium but there exist mutual influences transmitted via a common electromagnetic field. By employing concepts and techniques of open quantum systems we introduce coarse-graining to the physical variables--the medium, the quantum field, and the atom's internal degrees of freedom, in that order--to extract their averaged effects from the lowest tier progressively to the top tier. The first tier of coarse-graining provides the averaged effect of the medium upon the field, quantified by a complex permittivity (in the frequency domain) describing the response of the dielectric to the field in addition to its back action on the field through a stochastic forcing term. The last tier of coarse-graining over the atom's internal degrees of freedom results in an equation of motion for the atom's center of mass from which we can derive the force on the atom. Our nonequilibrium formulation provides a fully dynamical description of the atom's motion including back-action effects from all other relevant variables concerned. In the long-time limit we recover the known results for the atom-dielectric force when the combined system is in equilibrium or in a nonequilibrium stationary state.

Fluorine atom subsurface diffusion and reaction in photoresist

International Nuclear Information System (INIS)

Greer, Frank; Fraser, D.; Coburn, J.W.; Graves, David B.

2003-01-01

Kinetic studies of fluorine and deuterium atoms interacting with an OiR 897 10i i-line photoresist (PR) are reported. All experiments were conducted at room temperature. Films of this PR were coated on quartz-crystal microbalance (QCM) substrates and exposed to alternating fluxes of these atoms in a high vacuum apparatus. Mass changes of the PR were observed in situ and in real time during the atom beam exposures using the QCM. A molecular-beam sampled differentially pumped quadrupole mass spectrometer (QMS) was used to measure the species desorbing from the PR surface during the F and D atom exposures. During the D atom exposures, hydrogen abstraction and etching of the PR was observed, but no DF formation was detected. However, during the F atom exposures, the major species observed to desorb from the surface was DF, formed from fluorine abstraction of deuterium from the photoresist. No evidence of film etching or fluorine self-abstraction was observed. The film mass increased during F atom exposure, evidently due to the replacement of D by F in the film. The rate of DF formation and mass uptake were both characterized by the same kinetics: An initially rapid step declining exponentially with time (e -t/τ ), followed by a much slower step following inverse square root of time (t -1/2 ) kinetics. The initially rapid step was interpreted as surface abstraction of D by F to form DF, which desorbs, with subsequent F impacting the surface inserted into surface C dangling bonds. The slower step was interpreted as F atoms diffusing into the fluorinated photoresist, forming DF at the boundary of the fluorinated carbon layer. The t -1/2 kinetics of this step are interpreted to indicate that F diffusion through the fluorinated carbon layer is much slower than the rate of F abstraction of D to form DF, or the rate of F insertion into the carbon dangling bonds left behind after DF formation. A diffusion-limited growth model was formulated, and the model parameters are

Effect of surface pretreatment on interfacial chemical bonding states of atomic layer deposited ZrO2 on AlGaN

International Nuclear Information System (INIS)

Ye, Gang; Arulkumaran, Subramaniam; Ng, Geok Ing; Li, Yang; Ang, Kian Siong; Wang, Hong; Ng, Serene Lay Geok; Ji, Rong; Liu, Zhi Hong

2015-01-01

Atomic layer deposition (ALD) of ZrO 2 on native oxide covered (untreated) and buffered oxide etchant (BOE) treated AlGaN surface was analyzed by utilizing x-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy. Evidenced by Ga–O and Al–O chemical bonds by XPS, parasitic oxidation during deposition is largely enhanced on BOE treated AlGaN surface. Due to the high reactivity of Al atoms, more prominent oxidation of Al atoms is observed, which leads to thicker interfacial layer formed on BOE treated surface. The results suggest that native oxide on AlGaN surface may serve as a protecting layer to inhibit the surface from further parasitic oxidation during ALD. The findings provide important process guidelines for the use of ALD ZrO 2 and its pre-ALD surface treatments for high-k AlGaN/GaN metal–insulator–semiconductor high electron mobility transistors and other related device applications

A real time monitoring system

International Nuclear Information System (INIS)

Fontanini, Horacio; Galdoz, Erwin

1989-01-01

A real time monitoring system is described. It was initially developed to be used as a man-machine interface between a basic principles simulator of the Embalse Nuclear Power Plant and the operators. This simulator is under construction at the Bariloche Atomic Center's Process Control Division. Due to great design flexibility, this system can also be used in real plants. The system is designed to be run on a PC XT or AT personal computer with high resolution graphics capabilities. Three interrelated programs compose the system: 1) Graphics Editor, to build static image to be used as a reference frame where to show dynamically updated data. 2) Data acquisition and storage module. It is a memory resident module to acquire and store data in background. Data can be acquired and stored without interference with the operating system, via serial port or through analog-to-digital converter attached to the personal computer. 3) Display module. It shows the acquired data according to commands received from configuration files prepared by the operator. (Author) [es

Circuit QED with qutrits: Coupling three or more atoms via virtual-photon exchange

Science.gov (United States)

Zhao, Peng; Tan, Xinsheng; Yu, Haifeng; Zhu, Shi-Liang; Yu, Yang

2017-10-01

We present a model to describe a generic circuit QED system which consists of multiple artificial three-level atoms, namely, qutrits, strongly coupled to a cavity mode. When the state transition of the atoms disobeys the selection rules the process that does not conserve the number of excitations can happen determinatively. Therefore, we can realize coherent exchange interaction among three or more atoms mediated by the exchange of virtual photons. In addition, we generalize the one-cavity-mode mediated interactions to the multicavity situation, providing a method to entangle atoms located in different cavities. Using experimentally feasible parameters, we investigate the dynamics of the model including three cyclic-transition three-level atoms, for which the two lowest energy levels can be treated as qubits. Hence, we have found that two qubits can jointly exchange excitation with one qubit in a coherent and reversible way. In the whole process, the population in the third level of atoms is negligible and the cavity photon number is far smaller than 1. Our model provides a feasible scheme to couple multiple distant atoms together, which may find applications in quantum information processing.

Constraints on Σ nucleus dynamics from dirac phenomenology of Σ- atoms

International Nuclear Information System (INIS)

Mares, J.; Friedman, E.; Hebrew Univ., Jerusalem; Gal, A.; Jennings, B.K.

1995-05-01

Strong interaction level shifts and widths in Σ - atoms are analyzed by using a Σ nucleus optical potential constructed within the relativistic mean field approach. The analysis leads to potentials with a repulsive real part in the nuclear interior. The data are sufficient to establish the size of the isovector meson-hyperon coupling. Implications to Σ hypernuclei are discussed. (author). 36 refs., 2 tabs., 4 figs

Spatially resolved photoionization of ultracold atoms on an atom chip

International Nuclear Information System (INIS)

Kraft, S.; Guenther, A.; Fortagh, J.; Zimmermann, C.

2007-01-01

We report on photoionization of ultracold magnetically trapped Rb atoms on an atom chip. The atoms are trapped at 5 μK in a strongly anisotropic trap. Through a hole in the chip with a diameter of 150 μm, two laser beams are focused onto a fraction of the atomic cloud. A first laser beam with a wavelength of 778 nm excites the atoms via a two-photon transition to the 5D level. With a fiber laser at 1080 nm the excited atoms are photoionized. Ionization leads to depletion of the atomic density distribution observed by absorption imaging. The resonant ionization spectrum is reported. The setup used in this experiment is suitable not only to investigate mixtures of Bose-Einstein condensates and ions but also for single-atom detection on an atom chip

Current developments in TREAT hodoscope technology

International Nuclear Information System (INIS)

De Volpi, A.

1975-01-01

The development of fuel motion monitoring is traced from its inception through present operation and into future programs. After noting the role of fuel motion studies in terms of safety assurance for the LMFBR, the history of in-pile fuel monitoring is reviewed. The operational record of the present TREAT fast neutron hodoscope is summarized with attention to various performance features. Development plans for the TREAT hodoscope are described in some detail. Application of the hodoscope has been considered for eight safety facilities other than TREAT. In addition, there is a possible role for fuel monitoring techniques to be extended to real-time ex-vessel core surveillance in operating reactors. Certain intrinsic strengths of the hodoscope technique for material monitoring are identified. The pattern of development may be characterized as an adaptation of several technologies to fit available requirements and resources

Calculation of neutron shielding for a real loaded C-30 cask by code DORT

International Nuclear Information System (INIS)

Lacina, J.

1999-01-01

Measured neutron dose rates of real loaded C-30 casks for WWER spent fuel assemblies are compared with calculated values in the frame of benchmark calculation task. The part of this benchmark task concerning neutron shielding was calculated. Neutron sources values were taken from data presented by V. Chrapciak during the eighth symposium Atomic Energy Research, Bystrice pod Perstejnem in 1998 and the data about cask from the article of the same author from the Atomic Energy Research working group E meeting at Stolpen in 1998. (Author)

Real and mythical consequences of Chernobyl accident

International Nuclear Information System (INIS)

Osmachkin, V.S.

1999-01-01

This presentation describes the public Unacceptance of Nuclear Power as a consequence of Chernobyl Accident, an accident which was a severest event in the history of the nuclear industry. It was a shock for everybody, who has been involved in nuclear power programs. But nobody could expect that it was also the end romantic page in the nuclear story. The scale of the detriment was a great, and it could be compared with other big technological man-made catastrophes. But immediately after an accident mass media and news agencies started to transmit an information with a great exaggerations of the consequences of the event. In a report on the Seminar T he lessons of the Chernobyl - 1' in 1996 examples of such incorrect information, were cited. Particularly, in the mass media it was declared that consequences of the accident could be compared with a results of the second world war, the number of victims were more than hundred thousand people, more than million of children have the serious health detriments. Such and other cases of the misconstruction have been called as myths. The real consequences of Chernobyl disaster have been summed on the International Conference 'One decade after Chernobyl' - 2, in April 1996. A very important result of the Chernobyl accident was a dissemination of stable unacceptance of the everything connected with 'the atom'. A mystic horror from invisible mortal radiation has been inspired in the masses. And from such public attitude the Nuclear Power Programs in many countries have changed dramatically. A new more pragmatic and more careful atomic era started with a slogan: 'Kernkraftwerk ? Nein, danke'. No doubt, a Chernobyl accident was a serious technical catastrophe in atomic industry. The scale of detriment is connected with a number of involved peoples, not with a number of real victims. In comparison with Bhopal case, earthquakes, crashes of the airplanes, floods, traffic accidents and other risky events of our life - the Chernobyl is

Omalizumab treats chronic rhinosinusitis with nasal polyps and asthma together-a real life study.

Science.gov (United States)

Bidder, T; Sahota, J; Rennie, C; Lund, V J; Robinson, D S; Kariyawasam, H H

2018-03-01

Chronic rhinosinusitis with nasal polyps (CRSwNP) and asthma often coexist and thus treating both with one intervention is an attractive strategy. To prospectively evaluate whether treatment with the monoclonal antibody against IgE Omalizumab for severe allergic asthma also effectively treats co-existent CRSwNP. SNOT-22 and the ACQ-7 scores were recorded at 4 and 16 weeks of treatment in a cohort of patients with both CRSwNP and severe refractory allergic asthma treated with Omalizumab (n=13) according to UK guidelines for their severe asthma. SNOT-22 in a surgery only treated CRSwNP with asthma group (n=24) was compared. Rapid improvement was seen at 4 weeks and 16 weeks of treatment in both CRSwNP and asthma control. The improvement in CRSwNP with Omalizumab was similar to that seen in a group of patients who received upper airway surgery. Omalizumab treatment for severe allergic asthma also improves co-existent CRSwNP. Further clinical studies of current and emerging biological agents for severe asthma should include upper airway outcomes. These agents may be effective for severe CRSwNP and comparative studies with surgery are warranted.

Spin-splitting calculation for zincblende semiconductors using an atomic bond-orbital model

International Nuclear Information System (INIS)

Kao, Hsiu-Fen; Lo, Ikai; Chiang, Jih-Chen; Wang, Wan-Tsang; Hsu, Yu-Chi; Wu, Chieh-Lung; Gau, Ming-Hong; Chen, Chun-Nan; Ren, Chung-Yuan; Lee, Meng-En

2012-01-01

We develop a 16-band atomic bond-orbital model (16ABOM) to compute the spin splitting induced by bulk inversion asymmetry in zincblende materials. This model is derived from the linear combination of atomic-orbital (LCAO) scheme such that the characteristics of the real atomic orbitals can be preserved to calculate the spin splitting. The Hamiltonian of 16ABOM is based on a similarity transformation performed on the nearest-neighbor LCAO Hamiltonian with a second-order Taylor expansion over k-vector at the Γ point. The spin-splitting energies in bulk zincblende semiconductors, GaAs and InSb, are calculated, and the results agree with the LCAO and first-principles calculations. However, we find that the spin-orbit coupling between bonding and antibonding p-like states, evaluated by the 16ABOM, dominates the spin splitting of the lowest conduction bands in the zincblende materials.

Matrix Methods for Solving Hartree-Fock Equations in Atomic Structure Calculations and Line Broadening

Directory of Open Access Journals (Sweden)

Thomas Gomez

2018-04-01

Full Text Available Atomic structure of N-electron atoms is often determined by solving the Hartree-Fock equations, which are a set of integro-differential equations. The integral part of the Hartree-Fock equations treats electron exchange, but the Hartree-Fock equations are not often treated as an integro-differential equation. The exchange term is often approximated as an inhomogeneous or an effective potential so that the Hartree-Fock equations become a set of ordinary differential equations (which can be solved using the usual shooting methods. Because the Hartree-Fock equations are an iterative-refinement method, the inhomogeneous term relies on the previous guess of the wavefunction. In addition, there are numerical complications associated with solving inhomogeneous differential equations. This work uses matrix methods to solve the Hartree-Fock equations as an integro-differential equation. It is well known that a derivative operator can be expressed as a matrix made of finite-difference coefficients; energy eigenvalues and eigenvectors can be obtained by using linear-algebra packages. The integral (exchange part of the Hartree-Fock equation can be approximated as a sum and written as a matrix. The Hartree-Fock equations can be solved as a matrix that is the sum of the differential and integral matrices. We compare calculations using this method against experiment and standard atomic structure calculations. This matrix method can also be used to solve for free-electron wavefunctions, thus improving how the atoms and free electrons interact. This technique is important for spectral line broadening in two ways: it improves the atomic structure calculations, and it improves the motion of the plasma electrons that collide with the atom.

Time-Dependent Close-Coupling Methods for Electron-Atom/Molecule Scattering

International Nuclear Information System (INIS)

Colgan, James

2014-01-01

The time-dependent close-coupling (TDCC) method centers on an accurate representation of the interaction between two outgoing electrons moving in the presence of a Coulomb field. It has been extensively applied to many problems of electrons, photons, and ions scattering from light atomic targets. Theoretical Description: The TDCC method centers on a solution of the time-dependent Schrödinger equation for two interacting electrons. The advantages of a time-dependent approach are two-fold; one treats the electron-electron interaction essentially in an exact manner (within numerical accuracy) and a time-dependent approach avoids the difficult boundary condition encountered when two free electrons move in a Coulomb field (the classic three-body Coulomb problem). The TDCC method has been applied to many fundamental atomic collision processes, including photon-, electron- and ion-impact ionization of light atoms. For application to electron-impact ionization of atomic systems, one decomposes the two-electron wavefunction in a partial wave expansion and represents the subsequent two-electron radial wavefunctions on a numerical lattice. The number of partial waves required to converge the ionization process depends on the energy of the incoming electron wavepacket and on the ionization threshold of the target atom or ion.

The Atomic Energy of Canada Limited (AECL) employee health study

International Nuclear Information System (INIS)

Weeks, J.L.

1985-01-01

The Atomic Energy Health Study formally began in April 1980. The purpose of the study is to determine the causes of death among a population of radiation workers and to compare this information with data available for the causes of death in the general population. The study population and the implementation are briefly discussed. The aim of the study is to determine the real occupational risk of being a radiation worker. 3 refs

Intensification of oily waste waters purification by means of liquid atomization

Science.gov (United States)

Eskin, A. A.; Tkach, N. S.; Kim, M. I.; Zakharov, G. A.

2017-10-01

In this research, a possibility of using liquid atomization for improving the efficiency of purification of wastewater by different methods has been studied. By the introduced method and an experimental setup for wastewater purification, saturation rate increases with its purification by means of dissolved air flotation. Liquid atomization under excess pressure allows to gain a large interfacial area between the saturated liquid and air, which may increase the rate of purified liquid saturation almost twice, compared to the existing methods of saturation. Current disadvantages of liquid atomization used for intensification of wastewater purification include high energy cost and secondary emulsion of polluting agents. It is also known that by means of liquid atomization a process of ozonizing can be intensified. Large contact surface between the purified liquid and ozone-air mixture increases the oxidizing efficiency, which allows to diminish ozone discharge. Liquid atomization may be used for purification of wastewaters by ultraviolet radiation. Small drops of liquid will be proportionally treated by ultraviolet, which makes it possible to do purification even of turbid wastewaters. High-speed liquid motion will prevent the pollution of quartz tubes of ultraviolet lamps.

Coherent tunneling of atoms from Bose-condensed gases at finite temperatures

International Nuclear Information System (INIS)

Luxat, David L.; Griffin, Allan

2002-01-01

Tunneling of atoms between two trapped Bose-condensed gases at finite temperatures is explored using a many-body linear-response tunneling formalism similar to that used in superconductors. To lowest order, the tunneling currents can be expressed quite generally in terms of the single-particle Green's functions of isolated Bose gases. A coherent first-order tunneling Josephson current between two atomic Bose-Einstein condensates is found, in addition to coherent and dissipative contributions from second-order condensate-noncondensate and noncondensate-noncondensate tunneling. Our work is a generalization of Meier and Zwerger, who recently treated tunneling between uniform atomic Bose gases. We apply our formalism to the analysis of an out-coupling experiment induced by light wave fields, using a simple Bogoliubov-Popov quasiparticle approximation for the trapped Bose gas. For tunneling into the vacuum, we recover the results of Japha, Choi, Burnett, and Band, who recently pointed out the usefulness of studying the spectrum of out-coupled atoms. In particular, we show that the small tunneling current of noncondensate atoms from a trapped Bose gas has a broad spectrum of energies, with a characteristic structure associated with the Bogoliubov quasiparticle u 2 and v 2 amplitudes

Atomic polarizabilities

International Nuclear Information System (INIS)

Safronova, M. S.; Mitroy, J.; Clark, Charles W.; Kozlov, M. G.

2015-01-01

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

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.

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

Modelization of nanospace interaction involving a ferromagnetic atom: a spin polarization effect study by thermogravimetric analysis.

Science.gov (United States)

Santhanam, K S V; Chen, Xu; Gupta, S

2014-04-01

Ab initio studies of ferromagnetic atom interacting with carbon nanotubes have been reported in the literature that predict when the interaction is strong, a higher hybridization with confinement effect will result in spin polarization in the ferromagnetic atom. The spin polarization effect on the thermal oxidation to form its oxide is modeled here for the ferromagnetic atom and its alloy, as the above studies predict the 4s electrons are polarized in the atom. The four models developed here provide a pathway for distinguishing the type of interaction that exists in the real system. The extent of spin polarization in the ferromagnetic atom has been examined by varying the amount of carbon nanotubes in the composites in the thermogravimetric experiments. In this study we report the experimental results on the CoNi alloy which appears to show selective spin polarization. The products of the thermal oxidation has been analyzed by Fourier Transform Infrared Spectroscopy.

Dipole and quadrupole forces exerted on atoms in laser fields: The nonperturbative approach

International Nuclear Information System (INIS)

Sindelka, Milan; Moiseyev, Nimrod; Cederbaum, Lorenz S.

2006-01-01

Manipulation of cold atoms by lasers has so far been studied solely within the framework of the conventional dipole approximation, and the atom-light interaction has been treated using low order perturbation theory. Laser control of atomic motions has been ascribed exclusively to the corresponding light-induced dipole forces. In this work, we present a general theory to derive the potential experienced by an atom in a monochromatic laser field in a context analogous to the Born-Oppenheimer approximation for molecules in the field-free case. The formulation goes beyond the dipole approximation and gives rise to the field-atom coupling potential terms which so far have not been taken into consideration in theoretical or experimental studies. Contrary to conventional approaches, our method is based upon the many electron Floquet theory and remains valid also for high intensity laser fields (i.e., for a strongly nonperturbative atom-light interaction). As an illustration of the developed theory, we investigate the trapping of cold atoms in optical lattices. We find that for some atoms for specific laser parameters, despite the absence of the dipole force, the laser trapping is still possible due to the electric quadrupole forces. Namely, we show that by using realistic laser parameters one can form a quadrupole optical lattice which is sufficiently strong to trap Ca and Na atoms

Excitation of the shear horizontal mode in a monolayer by inelastic helium atom scattering

DEFF Research Database (Denmark)

Bruch, L. W.; Hansen, Flemming Yssing

2005-01-01

Inelastic scattering of a low-energy atomic helium beam (HAS) by a physisorbed monolayer is treated in the one-phonon approximation using a time-dependent wave,packet formulation. The calculations show that modes with shear horizontal polarization can be excited near high symmetry azimuths....... The diffraction and inelastic processes arise from a strong coupling of the incident atom to the target and the calculated results show large departures from expectations based on analogies to inelastic thermal neutron scattering....

Systematics of atom-atom collision strengths at high speeds

International Nuclear Information System (INIS)

Gillespie, G.H.; Inokuti, M.

1980-01-01

The collision strengths for atom-atom collisions at high speeds are calculated in the first Born approximation. We studied four classes of collisions, distinguished depending upon whether each of the collision partners becomes excited or not. The results of numerical calculations of the collision strengths are presented for all neutral atoms with Z< or =18. The calculations are based on atomic form factors and incoherent scattering functions found in the literature. The relative contribution of each class of collision processes to the total collision cross section is examined in detail. In general, inelastic processes dominate for low-Z atoms, while elastic scattering is more important for large Z. Other systematics of the collision strengths are comprehensively discussed. The relevant experimental literature has been surveyed and the results of this work for the three collision systems H-He, He-He, and H-Ar are compared with the data for electron-loss processes. Finally, suggestions are made for future work in measurements of atom-atom and ion-atom collision cross sections

Complex energies from real perturbation series for the LoSurdo-Stark effect in hydrogen by Borel-Pade approximants

Energy Technology Data Exchange (ETDEWEB)

Franceschini, V.; Grecchi, V.; Silverstone, H.J.

1985-09-01

The resonance energies for the hydrogen atom in an electric field, both the real and imaginary parts, have been calculated together from the real Rayleigh-Schroedinger perturbation series by Borel summation. Pade approximants were used to evaluate the Borel transform. The numerical results compare well with values obtained by the complex-coordinate variational method and by sequential use of Pade approximants.

Atomic Absorption, Atomic Fluorescence, and Flame Emission Spectrometry.

Science.gov (United States)

Horlick, Gary

1984-01-01

This review is presented in six sections. Sections focus on literature related to: (1) developments in instrumentation, measurement techniques, and procedures; (2) performance studies of flames and electrothermal atomizers; (3) applications of atomic absorption spectrometry; (4) analytical comparisons; (5) atomic fluorescence spectrometry; and (6)…

Fluorescence detection of white-beam X-ray absorption anisotropy: towards element-sensitive projections of local atomic structure

International Nuclear Information System (INIS)

Korecki, P.; Tolkiehn, M.; Dąbrowski, K. M.; Novikov, D. V.

2011-01-01

A method for a direct measurement of X-ray projections of the atomic structure is described. Projections of the atomic structure around Nb atoms in a LiNbO 3 single crystal were obtained from a white-beam X-ray absorption anisotropy pattern detected using Nb K fluorescence. Projections of the atomic structure around Nb atoms in a LiNbO 3 single crystal were obtained from a white-beam X-ray absorption anisotropy (XAA) pattern detected using Nb K fluorescence. This kind of anisotropy results from the interference of X-rays inside a sample and, owing to the short coherence length of a white beam, is visible only at small angles around interatomic directions. Consequently, the main features of the recorded XAA corresponded to distorted real-space projections of dense-packed atomic planes and atomic rows. A quantitative analysis of XAA was carried out using a wavelet transform and allowed well resolved projections of Nb atoms to be obtained up to distances of 10 Å. The signal of nearest O atoms was detected indirectly by a comparison with model calculations. The measurement of white-beam XAA using characteristic radiation indicates the possibility of obtaining element-sensitive projections of the local atomic structure in more complex samples

Stable atomic hydrogen: Polarized atomic beam source

International Nuclear Information System (INIS)

Niinikoski, T.O.; Penttilae, S.; Rieubland, J.M.; Rijllart, A.

1984-01-01

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.)

Highly excited atoms

International Nuclear Information System (INIS)

Kleppner, D.; Littman, M.G.; Zimmerman, M.L.

1981-01-01

Highly excited atoms are often called Rydberg atoms. These atoms have a wealth of exotic properties which are discussed. Of special interest, are the effects of electric and magnetic fields on Rydberg atoms. Ordinary atoms are scarcely affected by an applied electric or magnetic field; Rydberg atoms can be strongly distorted and even pulled apart by a relatively weak electric field, and they can be squeezed into unexpected shapes by a magnetic field. Studies of the structure of Rydberg atoms in electric and magnetic fields have revealed dramatic atomic phenomena that had not been observed before

Atomic mirrors for a Λ-type three-level atom

International Nuclear Information System (INIS)

Felemban, Nuha; Aldossary, Omar M; Lembessis, Vassilis E

2014-01-01

We propose atom mirror schemes for a three-level atom of Λ-type interacting with two evanescent fields, which are generated as a result of the total internal reflection of two coherent Gaussian laser beams at the interface of a dielectric prism with vacuum. The forces acting on the atom are derived by means of optical Bloch equations, based on the atomic density matrix elements. The theory is illustrated by setting up the equations of motion for 23 Na atom. Two types of excited schemes are examined, namely the cases in which the evanescent fields have polarization types of σ + −σ − and σ + −π. The equations are solved numerically and we get results for atomic trajectories for different parameters. The performance of the mirror for the two types of polarization schemes is quantified and discussed. The possibility of reflecting atoms at pre-determined directions is also discussed. (paper)

Linear-algebraic approach to electronic excitation of atoms and molecules by electron impact

International Nuclear Information System (INIS)

Collins, L.A.; Schneider, B.I.

1983-01-01

A linear-algebraic method, based on an integral equations formulation, is applied to the excitation of atoms and molecules by electron impact. Various schemes are devised for treating the one-electron terms that sometimes cause instabilities when directly incorporated into the solution matrix. These include introducing Lagrange undetermined multipliers and correlation terms. Good agreement between the method and other computational techniques is obtained for electron scattering for hydrogenic and Li-like atomic ions and for H 2 + in two- to five-state close-coupling calculations

WMO and atomic energy

Energy Technology Data Exchange (ETDEWEB)

NONE

1960-09-15

The growing interest of WMO in atomic energy was reflected in the decision of the Executive Committee in 1956 to establish a panel of experts to study the meteorological aspects of the nuclear energy. One of the major achievements of the panel, which has held two meetings since its inception, has been the preparation of a technical note treating fully the various meteorological problems resulting from the applications of the peaceful uses of atomic energy. Over the past four years, steady progress has also been made both in adapting nuclear techniques to meteorological uses and in providing advice and assistance. Much time and thought are now being devoted to the study of large-scale air mass movements, turbulent diffusion and the other meteorological processes on which the transport and gradual fall-out of radioactive debris depend. The safe location of nuclear plants and the disposal of radioactive waste are related problems in which WMO has also taken a very active interest. Another aspect of the help which WMO as an organization can provide is to help for the collection and analysis of radioactive material in the biosphere. Advances in nuclear physics have also opened up great possibilities for the use of radioactive isotopes in making meteorological and hydrometeorological measurements

Real-space grid implementation of the projector augmented wave method

DEFF Research Database (Denmark)

Mortensen, Jens Jørgen; Hansen, Lars Bruno; Jacobsen, Karsten Wedel

2005-01-01

A grid-based real-space implementation of the projector augmented wave sPAWd method of Blöchl fPhys. Rev. B 50, 17953 s1994dg for density functional theory sDFTd calculations is presented. The use of uniform three-dimensional s3Dd real-space grids for representing wave functions, densities...... valence wave functions that can be represented on relatively coarse grids. We demonstrate the accuracy of the method by calculating the atomization energies of 20 small molecules, and the bulk modulus and lattice constants of bulk aluminum. We show that the approach in terms of computational efficiency...... is comparable to standard plane-wave methods, but the memory requirements are higher....

Quasi-atoms

International Nuclear Information System (INIS)

Armbruster, P.

1976-01-01

The concept of a quasi-atom is discussed, and several experiments are described in which molecular or quasi-atomic transitions have been observed. X-ray spectra are shown for these experiments in which heavy ion projectiles were incident on various targets and the resultant combined system behaved as a quasi-atom. This rapidly developing field has already given new insight into atomic collision phenomena. (P.J.S.)

Atomic fusion, Gerrard atomic fusion

International Nuclear Information System (INIS)

Gerrard, T.H.

1980-01-01

In the approach to atomic fusion described here the heat produced in a fusion reaction, which is induced in a chamber by the interaction of laser beams and U.H.F. electromagnetic beams with atom streams, is transferred to a heat exchanger for electricity generation by a coolant flowing through a jacket surrounding the chamber. (U.K.)

Atomic Covalent Functionalization of Graphene

Science.gov (United States)

Johns, James E.; Hersam, Mark C.

2012-01-01

Conspectus Although graphene’s physical structure is a single atom thick, two-dimensional, hexagonal crystal of sp2 bonded carbon, this simple description belies the myriad interesting and complex physical properties attributed to this fascinating material. Because of its unusual electronic structure and superlative properties, graphene serves as a leading candidate for many next generation technologies including high frequency electronics, broadband photodetectors, biological and gas sensors, and transparent conductive coatings. Despite this promise, researchers could apply graphene more routinely in real-world technologies if they could chemically adjust graphene’s electronic properties. For example, the covalent modification of graphene to create a band gap comparable to silicon (~1 eV) would enable its use in digital electronics, and larger band gaps would provide new opportunities for graphene-based photonics. Towards this end, researchers have focused considerable effort on the chemical functionalization of graphene. Due to its high thermodynamic stability and chemical inertness, new methods and techniques are required to create covalent bonds without promoting undesirable side reactions or irreversible damage to the underlying carbon lattice. In this Account, we review and discuss recent theoretical and experimental work studying covalent modifications to graphene using gas phase atomic radicals. Atomic radicals have sufficient energy to overcome the kinetic and thermodynamic barriers associated with covalent reactions on the basal plane of graphene but lack the energy required to break the C-C sigma bonds that would destroy the carbon lattice. Furthermore, because they are atomic species, radicals substantially reduce the likelihood of unwanted side reactions that confound other covalent chemistries. Overall, these methods based on atomic radicals show promise for the homogeneous functionalization of graphene and the production of new classes of two

SOMOTE_EASY: AN ALGORITHM TO TREAT THE CLASSIFICATION ISSUE IN REAL DATABASES

Directory of Open Access Journals (Sweden)

Hugo Leonardo Pereira Rufino

2016-04-01

Full Text Available Most classification tools assume that data distribution be balanced or with similar costs, when not properly classified. Nevertheless, in practical terms, the existence of database where unbalanced classes occur is commonplace, such as in the diagnosis of diseases, in which the confirmed cases are usually rare when compared with a healthy population. Other examples are the detection of fraudulent calls and the detection of system intruders. In these cases, the improper classification of a minority class (for instance, to diagnose a person with cancer as healthy may result in more serious consequences that incorrectly classify a majority class. Therefore, it is important to treat the database where unbalanced classes occur. This paper presents the SMOTE_Easy algorithm, which can classify data, even if there is a high level of unbalancing between different classes. In order to prove its efficiency, a comparison with the main algorithms to treat classification issues was made, where unbalanced data exist. This process was successful in nearly all tested databases

Calculation of high rydberg levels of atom Zn with the WBEPM theory

International Nuclear Information System (INIS)

Zheng, Nengwu; Li, Zhengquan; Fan, Jing; Ma, Dongxia; Zhou, Tao

2002-01-01

Within the weakest bound electron potential model theory, we treat the many-valance electron system of atom Zn single electron and use the extended martin's expression to determine parameters. The results are satisfying with deviations no more than 1cm -1 compared with the experimental values. (author)

Long-term Course of Alzheimer Disease in Patients Treated According to the Dutch Dementia Guideline at a Memory Clinic: A "Real-Life" Study.

Science.gov (United States)

Droogsma, Erika; van Asselt, Dieneke; van Steijn, Jolanda; Diekhuis, Marjolein; Veeger, Nic; De Deyn, Peter P

2016-01-01

There is little knowledge of the long-term course of Alzheimer disease (AD) in light of current pharmacological and nonpharmacological interventions provided in a "real-life" setting. The Frisian Alzheimer's Disease Cohort study is a "real-life" study of the course of AD in patients (n=576) treated with pharmacological (ie, cholinesterase inhibitors) and nonpharmacological (ie, case management, respite care) interventions. Disease course was described by changes in cognition (Mini Mental State Examination, clock-drawing test) and number of types of professional care applying a repeated-measures analysis using a marginal model (population-based average model). In addition, behavioral and psychological symptoms, and proportions of nursing home admissions and deaths were investigated. During 3.5 years, the average Mini Mental State Examination decreased from 22.24 to 18.91, the clock-drawing test score increased from 3.38 to 4.05, the number of types of professional care increased from 0.85 to 2.64, and the patients with behavioral and psychological symptoms increased from 29.0% to 70.2%. The proportion of patients admitted to a nursing home was 40.8% and 41.0% died. Cognition and behaviour of AD patients deteriorated accompanied with an increase in care-dependency during 3.5 years. Nevertheless, compared with the precholinesterase inhibitor era, current pharmacological and nonpharmacological interventions appear to slow cognitive decline, which emphasizes that they seem to have a favorable effect.

Interferometry with atoms

International Nuclear Information System (INIS)

Helmcke, J.; Riehle, F.; Witte, A.; Kisters, T.

1992-01-01

Physics and experimental results of atom interferometry are reviewed and several realizations of atom interferometers are summarized. As a typical example of an atom interferometer utilizing the internal degrees of freedom of the atom, we discuss the separated field excitation of a calcium atomic beam using four traveling laser fields and demonstrate the Sagnac effect in a rotating interferometer. The sensitivity of this interferometer can be largely increased by use of slow atoms with narrow velocity distribution. We therefore furthermore report on the preparation of a laser cooled and deflected calcium atomic beam. (orig.)

Theoretical femtosecond physics atoms and molecules in strong laser fields

CERN Document Server

Grossmann, Frank

2013-01-01

Theoretical investigations of atoms and molecules interacting with pulsed or continuous wave lasers up to atomic field strengths on the order of 10^16 W/cm² are leading to an understanding of many challenging experimental discoveries. This book deals with the basics of femtosecond physics and goes up to the latest applications of new phenomena. The book presents an introduction to laser physics with mode-locking and pulsed laser operation. The solution of the time-dependent Schrödinger equation is discussed both analytically and numerically. The basis for the non-perturbative treatment of laser-matter interaction in the book is the numerical solution of the time-dependent Schrödinger equation. The light field is treated classically, and different possible gauges are discussed. Physical phenonema, ranging from Rabi-oscillations in two-level systems to the ionization of atoms, the generation of high harmonics, the ionization and dissociation of molecules as well as the control of chemical reactions are pre...

Quantum Monte-Carlo programming for atoms, molecules, clusters, and solids

International Nuclear Information System (INIS)

Schattke, Wolfgang; Diez Muino, Ricardo

2013-01-01

This is a book that initiates the reader into the basic concepts and practical applications of Quantum Monte Carlo. Because of the simplicity of its theoretical concept, the authors focus on the variational Quantum Monte Carlo scheme. The reader is enabled to proceed from simple examples as the hydrogen atom to advanced ones as the Lithium solid. In between, several intermediate steps are introduced, including the Hydrogen molecule (2 electrons), the Lithium atom (3 electrons) and expanding to an arbitrary number of electrons to finally treat the three-dimensional periodic array of Lithium atoms in a crystal. The book is unique, because it provides both theory and numerical programs. It pedagogically explains how to transfer into computational tools what is usually described in a theoretical textbook. It also includes the detailed physical understanding of methodology that cannot be found in a code manual. The combination of both aspects allows the reader to assimilate the fundamentals of Quantum Monte Carlo not only by reading but also by practice.

Endothelial cell behaviour on gas-plasma-treated PLA surfaces: the roles of surface chemistry and roughness.

Science.gov (United States)

Shah, Amita; Shah, Sarita; Mani, Gopinath; Wenke, Joseph; Agrawal, Mauli

2011-04-01

Glow-discharge gas-plasma (GP) treatment has been shown to induce surface modifications such that cell adhesion and growth are enhanced. However, it is not known which gas used in GP treatment is optimal for endothelial cell function. Polylactic acid (PLA) films treated oxygen, argon, or nitrogen GP were characterized using contact angles, scanning electron microscopy, atomic force microscopy, optical profilometry, and x-ray photoelectron spectroscopy. All three GP treatments decreased the carbon atomic concentration and surface roughness and increased the oxygen atomic concentration. Human umbilical vein endothelial cells were cultured on the PLA films for up to 7 days. Based on proliferation and live/dead assays, surface chemistry was shown to have the greatest effect on the attachment, proliferation, and viability of these cells, while roughness did not have a significant influence. Of the different gases, endothelial cell viability, attachment and proliferation were most significantly increased on PLA surfaces treated with oxygen and argon gas plasma. Copyright © 2010 John Wiley & Sons, Ltd.

Conduction of molecular electronic devices: Qualitative insights through atom-atom polarizabilities

International Nuclear Information System (INIS)

Stuyver, T.; Fias, S.; De Proft, F.; Geerlings, P.; Fowler, P. W.

2015-01-01

The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability

Conduction of molecular electronic devices: Qualitative insights through atom-atom polarizabilities

Energy Technology Data Exchange (ETDEWEB)

Stuyver, T.; Fias, S., E-mail: sfias@vub.ac.be; De Proft, F.; Geerlings, P. [ALGC, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussel (Belgium); Fowler, P. W. [Department of Chemistry, University of Sheffield, Sheffield S3 7HF (United Kingdom)

2015-03-07

The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.

Conduction of molecular electronic devices: qualitative insights through atom-atom polarizabilities.

Science.gov (United States)

Stuyver, T; Fias, S; De Proft, F; Fowler, P W; Geerlings, P

2015-03-07

The atom-atom polarizability and the transmission probability at the Fermi level, as obtained through the source-and-sink-potential method for every possible configuration of contacts simultaneously, are compared for polycyclic aromatic compounds. This comparison leads to the conjecture that a positive atom-atom polarizability is a necessary condition for transmission to take place in alternant hydrocarbons without non-bonding orbitals and that the relative transmission probability for different configurations of the contacts can be predicted by analyzing the corresponding atom-atom polarizability. A theoretical link between the two considered properties is derived, leading to a mathematical explanation for the observed trends for transmission based on the atom-atom polarizability.

Atomic physics using relativistic H- beams

International Nuclear Information System (INIS)

Bryant, H.C.

2005-01-01

Full text: An 8 GeV hydrogen atom can traverse a focused laser beam of width of 1 micron in a time of 353 attoseconds in its rest frame. A design is currently underway at Fermilab for a superconducting linear accelerator that will accelerate H - ions to 8 GeV. This 'Proton Driver' beam is intended to be injected, after stripping down to protons, into the 120 GeV Main Injector for the mass production of neutrinos aimed at a neutrino detector (MINOS) in a mine shaft in Soudan, Minnesota (USA) for the study of neutrino oscillations. It has not passed unnoticed that with some advance planning a few nanoamps from the up-to-250 mA beam could be diverted for atomic physics experiments. Relativistic kinematics enable the creation of extreme conditions for a beam atom. For example, the Doppler shift allows a very large tuning range in the atom's rest frame of a laser beam that is fixed- frequency in the lab. At 8 GeV the rest frame Doppler shift ranges from a factor of 19 in the forward direction to 0.05 backward. The laser intensity is enhanced by the square of the Doppler shift, so that the world's most intense laser beam would be amplified by a factor of 360 in the atom's rest frame. Furthermore, although there are extreme changes in the frequency and intensity in the atom's frame as one changes the intersection angle, the ponderomotive potential remains constant, as it is a relativistic invariant. One of the interesting problems that arises in the planning for this accelerator is the stripping of electrons from the negative ions by photodetachment from Doppler shifted thermal photons. We estimate that, if the transfer lines are kept at 300 K (room temperature), the mean free path at 8 GeV for stripping from collisions with cavity radiation is about 1300 km. The physics of the interactions of such a beam with very thin material foils, again in the attosecond regime, has been treated theoretically, but has not been studied experimentally at such high energies. We will

Magnetic atom optics: mirrors, guides, traps, and chips for atoms

Energy Technology Data Exchange (ETDEWEB)

Hinds, E.A.; Hughes, I.G. [Sussex Centre for Optical and Atomic Physics, University of Sussex, Brighton (United Kingdom)

1999-09-21

For the last decade it has been possible to cool atoms to microkelvin temperatures ({approx}1 cm s{sup -1}) using a variety of optical techniques. Light beams provide the very strong frictional forces required to slow atoms from room temperature ({approx}500 m s{sup -1}). However, once the atoms are cold, the relatively weak conservative forces of static electric and magnetic fields play an important role. In our group we have been studying the interaction of cold rubidium atoms with periodically magnetized data storage media. Here we review the underlying principles of the forces acting on atoms above a suitably magnetized substrate or near current-carrying wires. We also summarize the status of experiments. These structures can be used as smooth or corrugated reflectors for controlling the trajectories of cold atoms. Alternatively, they may be used to confine atoms to a plane, a line, or a dot and in some cases to reach the quantum limit of confinement. Atoms levitated above a magnetized surface can be guided electrostatically by wires deposited on the surface. The flow and interaction of atoms in such a structure may form the basis of a new technology, 'integrated atom optics' which might ultimately be capable of realizing a quantum computer. (author)

Development of nanomanipulator using a high-speed atomic force microscope coupled with a haptic device

International Nuclear Information System (INIS)

Iwata, F.; Ohashi, Y.; Ishisaki, I.; Picco, L.M.; Ushiki, T.

2013-01-01

The atomic force microscope (AFM) has been widely used for surface fabrication and manipulation. However, nanomanipulation using a conventional AFM is inefficient because of the sequential nature of the scan-manipulation scan cycle, which makes it difficult for the operator to observe the region of interest and perform the manipulation simultaneously. In this paper, a nanomanipulation technique using a high-speed atomic force microscope (HS-AFM) is described. During manipulation using the AFM probe, the operation is periodically interrupted for a fraction of a second for high-speed imaging that allows the topographical image of the manipulated surface to be periodically updated. With the use of high-speed imaging, the interrupting time for imaging can be greatly reduced, and as a result, the operator almost does not notice the blink time of the interruption for imaging during the manipulation. This creates a more intuitive interface with greater feedback and finesse to the operator. Nanofabrication under real-time monitoring was performed to demonstrate the utility of this arrangement for real-time nanomanipulation of sample surfaces under ambient conditions. Furthermore, the HS-AFM is coupled with a haptic device for the human interface, enabling the operator to move the HS-AFM probe to any position on the surface while feeling the response from the surface during the manipulation. - Highlights: • A nanomanipulater based on a high-speed atomic force microscope was developped. • High-speed imaging provides a valuable feedback during the manipulation operation. • Operator can feel the response from the surface via a haptic device during manipulation. • Nanofabrications under real-time monitoring were successfully performed

Low energy atom-atom collisions

International Nuclear Information System (INIS)

Child, M.S.

1980-01-01

The semiclassical theory of atom-atom potential scattering and of low energy inelastic atom-atom scattering is reviewed. Particular attention is given to the origin and interpretation of rainbow structure, diffraction oscillations and exchange oscillations in the potential scattering differential cross-section, and to the glory structure and symmetry oscillations in the integral cross-section. Available methods for direct inversion of the cross-section data to recover the potential are reviewed in some detail. The theory of non-adiabatic transitions is introduced by a short discussion of interaction mechanisms and of diabetic and adiabatic representations. Analytical S matrix elements are presented for two state curve-crossing (Landau-Zener-Stuckelberg), Demkov and Nikitin models. The relation between Stuckelberg oscillations in the S matrix and in the differential cross-section is discussed in terms of interference between trajectories belonging to two different classical deflection functions. The energy dependences of the inelastic integral cross-section for curve-crossing and Demkov type transitions are also discussed. Finally the theory is reviewed in relation to a recent close-coupled study of fine structure transitions in F( 2 P) + Xe( 2 S) scattering

Double tungsten coil atomic absorption spectrometer based on an acousto-optic tunable filter

International Nuclear Information System (INIS)

Jora, M.Z.; Nóbrega, J.A.; Rohwedder, J.J.R.; Pasquini, C.

2015-01-01

An atomic absorption spectrometer based on a quartz acousto-optic tunable filter (AOTF) monochromator operating in the 271–453 nm range, is described. The instrument was tailored to study the formation and evolution of electrothermal atomic cloud induced either by one or two tungsten coils. The spectrometer also includes a fast response programmable photomultiplier module for data acquisition, and a power supply capable of driving two parallel tungsten coils independently. The atomization cell herein described was manufactured in PTFE and presents a new design with reduced size. Synchronization between the instant of power delivering to start the atomization process and the detection was achieved, allowing for monitoring the atomization and thermal events synchronously and in real time. Absorption signals can be sampled at a rate of a few milliseconds, compatible with the fast phenomena that occur with electrothermal metallic atomizers. The instrument performance was preliminarily evaluated by monitoring the absorption of radiation of atomic clouds produced by standard solutions containing chromium or lead. Its quantitative performance was evaluated by using Cr aqueous solutions, resulting in detection limits as low as 0.24 μg L −1 , and a relative standard deviation of 3%. - Highlights: • The use of an Acousto-Optic Tunable Filter (AOTF) as monochromator element in WC AAS is presented for the first time. • The system includes the possibility of using one or two parallel coils. • We propose a new atomization cell design, manufactured on PTFE with reduced size. • The temperature of the coils and the atomic clouds of Pb and Cr were observed synchronously with high temporal resolution

Classical descriptions of the electron trajectories in the He atom

International Nuclear Information System (INIS)

Miko, A.; Toekesi, K.

2006-01-01

Complete text of publication follows. The classical-trajectory Monte Carlo method (CTMC) treats the atomic systems as small solar-systems, where the electrons are moving around the nucleus in properly chosen Kepler-orbits. It is also well known that the multi-electron classical atomic systems are instable due to the autoionization through electron-electron interactions. Therefore most of the classical descriptions use the so called independent particle approach, i.e. they neclect the electron-electron interactions. In the quasiclassical trajectory Monte Carlo method (QCTMC) appears a qualitative improvement of the classical description of the multi-electron atoms namely the electron-electron interaction is entirely taken into account by the help of the extra potentials providing the validations of the Pauli exclusion principle and the Heisenberg uncertainty principle. The extra potentials ensure that the multi electron atoms are stable even if all electron-electron interactions are taken into account. The extra potentials - representing the constrains - can be written in the following form [1] V τ -2 f(τp; ξ); where f is the monotonic decreasing function of the relative distance τ and momentum p and ξ is the constant characterized the given atomic state. Figure 1. shows the typical electron trajectories in the helium atom. The calculations were carried out using CTMC model when the electron-electron interaction is neglected (Fig. 1a). In this case the He atom is stable and the electron orbits are closed. However, when the electron-electron interaction is taken into account in the CTMC model the electron trajectories in the He atom show chaotic behavior and after a few cycles autoionization occurs (Fig. 1b). In the QCTMC model the electron trajectories are also closed and stable (Fig. 1c). (author)

Spontaneous emission spectra and simulating multiple spontaneous generation coherence in a five-level atomic medium

International Nuclear Information System (INIS)

Li Jiahua; Liu Jibing; Qi Chunchao; Chen Aixi

2006-01-01

We investigate the features of the spontaneous emission spectra in a coherently driven cold five-level atomic system by means of a radio frequency (rf) or microwave field driving a hyperfine transition within the ground state. It is shown that a few interesting phenomena such as spectral-line narrowing, spectral-line enhancement, spectral-line suppression, and spontaneous emission quenching can be realized by modulating the frequency and intensity of the rf-driving field in our system. In the dressed-state picture of the coupling and rf-driving fields, we find that this coherently driven atomic system has three close-lying levels so that multiple spontaneously generated coherence (SGC) arises. Our considered atomic model can be found in real atoms, such as rubidium or sodium, so a corresponding experiment can be done to observe the expected phenomena related to SGC reported by Fountoulakis et al. [Phys. Rev. A 73, 033811 (2006)], since no rigorous conditions are required

Mechanism of yttrium atom formation in electrothermal atomization from metallic and metal-carbide surfaces of a heated graphite atomizer in atomic absorption spectrometry

International Nuclear Information System (INIS)

Wahab, H.S.; Chakrabarti, C.L.

1981-01-01

Mechanism of Y atom formation from pyrocoated graphite, tantalum and tungsten metal surfaces of a graphite tube atomizer has been studied and a mechanism for the formation for Y atoms is proposed for the first time. (author)

Atomic Physics 16: Sixteenth International Conference on Atomic Physics. Proceedings

International Nuclear Information System (INIS)

Baylis, W.E.; Drake, G.W.

1999-01-01

These proceedings represent papers presented at the 16th International Conference on Atomic Physics held in Windsor, Ontario, Canada, in August, 1998. The topics discussed included a wide array of subjects in atomic physics such as atom holography, alignment in atomic collisions, coulomb-interacting particles, muon experiments, x-rays from comets, atomic electron collisions in intense laser fields, spectroscopy of trapped ions, and Bose-Einstein condensates. This conference represents the single most important meeting world wide on fundamental advances in atomic physics. There were 30 papers presented at the conference,out of which 4 have been abstracted for the Energy, Science and Technology database

STATISTICAL ANALYSIS OF THE HEAVY NEUTRAL ATOMS MEASURED BY IBEX

International Nuclear Information System (INIS)

Park, Jeewoo; Kucharek, Harald; Möbius, Eberhard; Galli, André; Livadiotis, George; Fuselier, Steve A.; McComas, David J.

2015-01-01

We investigate the directional distribution of heavy neutral atoms in the heliosphere by using heavy neutral maps generated with the IBEX-Lo instrument over three years from 2009 to 2011. The interstellar neutral (ISN) O and Ne gas flow was found in the first-year heavy neutral map at 601 keV and its flow direction and temperature were studied. However, due to the low counting statistics, researchers have not treated the full sky maps in detail. The main goal of this study is to evaluate the statistical significance of each pixel in the heavy neutral maps to get a better understanding of the directional distribution of heavy neutral atoms in the heliosphere. Here, we examine three statistical analysis methods: the signal-to-noise filter, the confidence limit method, and the cluster analysis method. These methods allow us to exclude background from areas where the heavy neutral signal is statistically significant. These methods also allow the consistent detection of heavy neutral atom structures. The main emission feature expands toward lower longitude and higher latitude from the observational peak of the ISN O and Ne gas flow. We call this emission the extended tail. It may be an imprint of the secondary oxygen atoms generated by charge exchange between ISN hydrogen atoms and oxygen ions in the outer heliosheath

Analysis of an Air Conditioning Coolant Solution for Metal Contamination Using Atomic Absorption Spectroscopy: An Undergraduate Instrumental Analysis Exercise Simulating an Industrial Assignment

Science.gov (United States)

Baird, Michael J.

2004-01-01

A real-life analytical assignment is presented to students, who had to examine an air conditioning coolant solution for metal contamination using an atomic absorption spectroscopy (AAS). This hands-on access to a real problem exposed the undergraduate students to the mechanism of AAS, and promoted participation in a simulated industrial activity.

Self-consistent average-atom scheme for electronic structure of hot and dense plasmas of mixture

International Nuclear Information System (INIS)

Yuan Jianmin

2002-01-01

An average-atom model is proposed to treat the electronic structures of hot and dense plasmas of mixture. It is assumed that the electron density consists of two parts. The first one is a uniform distribution with a constant value, which is equal to the electron density at the boundaries between the atoms. The second one is the total electron density minus the first constant distribution. The volume of each kind of atom is proportional to the sum of the charges of the second electron part and of the nucleus within each atomic sphere. By this way, one can make sure that electrical neutrality is satisfied within each atomic sphere. Because the integration of the electron charge within each atom needs the size of that atom in advance, the calculation is carried out in a usual self-consistent way. The occupation numbers of electron on the orbitals of each kind of atom are determined by the Fermi-Dirac distribution with the same chemical potential for all kinds of atoms. The wave functions and the orbital energies are calculated with the Dirac-Slater equations. As examples, the electronic structures of the mixture of Au and Cd, water (H 2 O), and CO 2 at a few temperatures and densities are presented

Self-consistent average-atom scheme for electronic structure of hot and dense plasmas of mixture.

Science.gov (United States)

Yuan, Jianmin

2002-10-01

An average-atom model is proposed to treat the electronic structures of hot and dense plasmas of mixture. It is assumed that the electron density consists of two parts. The first one is a uniform distribution with a constant value, which is equal to the electron density at the boundaries between the atoms. The second one is the total electron density minus the first constant distribution. The volume of each kind of atom is proportional to the sum of the charges of the second electron part and of the nucleus within each atomic sphere. By this way, one can make sure that electrical neutrality is satisfied within each atomic sphere. Because the integration of the electron charge within each atom needs the size of that atom in advance, the calculation is carried out in a usual self-consistent way. The occupation numbers of electron on the orbitals of each kind of atom are determined by the Fermi-Dirac distribution with the same chemical potential for all kinds of atoms. The wave functions and the orbital energies are calculated with the Dirac-Slater equations. As examples, the electronic structures of the mixture of Au and Cd, water (H2O), and CO2 at a few temperatures and densities are presented.

Atomic diffusion theory challenging the Cahn-Hilliard method

International Nuclear Information System (INIS)

Nastar, M.

2014-01-01

behaviors of the vacancy, the latter treated as either a conservative species (fixed concentration) or a nonconservative species (time-dependent equilibrium concentration). Relying on the same vacancy diffusion model, we perform kinetic Monte Carlo simulations starting from a sinusoidal composition modulation in binary model alloys, with no interaction or nearest-neighbor interactions leading to clustering or ordering tendencies, along the [100] crystallographic direction of a body centered cubic (bcc) lattice. The resulting temporal variation of the modulation amplitude is compared to the corresponding SCMF equations. Qualitative and satisfying quantitative agreements systematically strengthen our theoretical conclusions. The model alloys are shown to be representative enough of some real alloys, so that one may expect these new heterogeneous correlation effects to be non-negligible in these alloys. (author)

Inversion of the total cross sections for electron-molecule and electron-atom scattering

International Nuclear Information System (INIS)

Lun, D.R.; Amos, K.; Allen, L.J.

1994-01-01

Inverse scattering theory has been applied to construct the interaction potentials from total cross sections as a function of energy for electrons scattered off of atoms and molecules. The underlying potentials are assumed to be real and energy independent and are evaluated using the Eikonal approximation and with real phase shifts determined from the total cross sections. The inversion potentials have been determined using either a high energy limit approximation or by using a fixed energy inversion method at select energies. These procedures have been used to analyse e - - CH 4 , e - - SiH 4 , e - -Kr and e - -Xe scattering data in particular. 14 refs., 1 tabs., 3 figs

Real time analysis under EDS

International Nuclear Information System (INIS)

Schneberk, D.

1985-07-01

This paper describes the analysis component of the Enrichment Diagnostic System (EDS) developed for the Atomic Vapor Laser Isotope Separation Program (AVLIS) at Lawrence Livermore National Laboratory (LLNL). Four different types of analysis are performed on data acquired through EDS: (1) absorption spectroscopy on laser-generated spectral lines, (2) mass spectrometer analysis, (3) general purpose waveform analysis, and (4) separation performance calculations. The information produced from this data includes: measures of particle density and velocity, partial pressures of residual gases, and overall measures of isotope enrichment. The analysis component supports a variety of real-time modeling tasks, a means for broadcasting data to other nodes, and a great degree of flexibility for tailoring computations to the exact needs of the process. A particular data base structure and program flow is common to all types of analysis. Key elements of the analysis component are: (1) a fast access data base which can configure all types of analysis, (2) a selected set of analysis routines, (3) a general purpose data manipulation and graphics package for the results of real time analysis. Each of these components are described with an emphasis upon how each contributes to overall system capability. 3 figs

Method of the reduced-added Green function in the calculation of atomic polarizabilities

International Nuclear Information System (INIS)

Chernov, V.E.; Dorofeev, D.L.; Kretinin, I.Yu.; Zon, B.A.

2005-01-01

The Green function in the quantum defect theory provides an exact account for high-excited and continuum electronic states. We modify it by taking into account the ground and low-excited states using their wave functions calculated ab initio. As an application, we present a simple and efficient semianalytical method for the calculation of atomic electric frequency-dependent scalar dipole polarizability, for both real and imaginary frequencies. The polarizabilities calculated for some atoms (Li, Na, K, Be, Mg, Ca, Si, P, S, O, Al, Ge, C, N, F, He, Ne, Ar, Kr, and Xe) are compared with existing methods of computational quantum chemistry and with experiments; good accuracy of the proposed method is demonstrated

A low-cost vaporization-atomization system for atomic absorption spectrometry

International Nuclear Information System (INIS)

Bruhn F, C.G.; Ambiado V, F.; Woerner V, R.

1990-01-01

A low-cost vaporization-atomization system for atomic absorption spectrometry is developed as an alternative to the use of a graphite furnace in electrothermal atomic absorption spectrometry. (Author)

Using real-time fMRI brain-computer interfacing to treat eating disorders.

Science.gov (United States)

Sokunbi, Moses O

2018-05-15

Real-time functional magnetic resonance imaging based brain-computer interfacing (fMRI neurofeedback) has shown encouraging outcomes in the treatment of psychiatric and behavioural disorders. However, its use in the treatment of eating disorders is very limited. Here, we give a brief overview of how to design and implement fMRI neurofeedback intervention for the treatment of eating disorders, considering the basic and essential components. We also attempt to develop potential adaptations of fMRI neurofeedback intervention for the treatment of anorexia nervosa, bulimia nervosa and binge eating disorder. Copyright © 2018 Elsevier B.V. All rights reserved.

Atom localization via controlled spontaneous emission in a five-level atomic system

International Nuclear Information System (INIS)

Wang Zhiping; Yu Benli; Zhu Jun; Cao Zhigang; Zhen Shenglai; Wu Xuqiang; Xu Feng

2012-01-01

We investigate the one- and two-dimensional atom localization behaviors via spontaneous emission in a coherently driven five-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of atom localization behaviors can be significantly improved via adjusting the system parameters. More importantly, the two-dimensional atom localization patterns reveal that the maximal probability of finding an atom within the sub-wavelength domain of the standing waves can reach unity when the corresponding conditions are satisfied. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization. - Highlights: ► One- and two-dimensional atom localization behaviors via spontaneous emission in five-level atoms are investigated. ► An assisting radio-frequency field is used to control the atom localization behaviors. ► High-precision and high-resolution two-dimensional atom localization can be realized in this scheme.

Three-atom clusters

International Nuclear Information System (INIS)

Pen'kov, F.M.

1998-01-01

The Born-Oppenheimer approximation is used to obtain an equation for the effective interaction in three atoms bound by a single electron. For low binding energies in an 'electron + atom' pair, long-range forces arise between the atoms, leading to bound states when the size of the three-atom cluster is a few tens of angstrom. A system made of alkali-metal atoms is considered as an example

Radioactive waste management at Narora atomic power station in India

International Nuclear Information System (INIS)

Prasad, P.N.; Gupta, J.P.; Mittal, S.

2001-01-01

Modern society creates waste material, which have to be disposed of in nature without disturbing the ecological equilibrium. Hence effective waste management in all industries is a major concern today. Narora Atomic Power Station (NAPS) generates low and intermediate level liquid, solid and gaseous wastes during its operation and maintenance. The generation of wastes is controlled at the source itself. The wastes are managed by adequate and appropriate treatment before being released into the environment. Different types of liquid wastes are treated by chemical co-precipitation, ion exchange, evaporation, filtration, and dilution techniques. For handling and conditioning of solid wastes, volume reduction techniques such as incineration and baling are employed. The treated wastes are immobilised by incorporation into cement and polymer matrices. Gaseous waste is cleaned by passing through pre-filters and high efficiency particulate (HEPA) filters and diluted with inactive air prior to release to the atmosphere through a 145 m high stack to get further atmospheric dilution. Regular monitoring up to 30 km radius is carried out by fully equipped Environmental Survey and Micrometeorological Laboratory which functions independently under the Directorate of Health and Safety, Bhabha Atomic Research Centre (BARC), Mumbai. So far, the annual maximum dose to the public around NAPS is reported to be 0.2 to 0.3% of limit of 1 mSv/year recommended by the International Commission on Radiological Protection (ICRP). A decade of experience has proved that present practices of nuclear waste management at Narora Atomic Power Station are quite safe and effective with respect to ecological equilibrium. (author)

Atomic Fisher information versus atomic number

International Nuclear Information System (INIS)

Nagy, A.; Sen, K.D.

2006-01-01

It is shown that the Thomas-Fermi Fisher information is negative. A slightly more sophisticated model proposed by Gaspar provides a qualitatively correct expression for the Fisher information: Gaspar's Fisher information is proportional to the two-third power of the atomic number. Accurate numerical calculations show an almost linear dependence on the atomic number

Atomic-fluorescence spectrophotometry

International Nuclear Information System (INIS)

Bakhturova, N.F.; Yudelevich, I.G.

1975-01-01

Atomic-fluorescence spectrophotometry, a comparatively new method for the analysis of trace quantities, has developed rapidly in the past ten years. Theoretical and experimental studies by many workers have shown that atomic-fluorescence spectrophotometry (AFS) is capable of achieving a better limit than atomic absorption for a large number of elements. The present review examines briefly the principles of atomic-fluorescence spectrophotometry and the types of fluorescent transition. The excitation sources, flame and nonflame atomizers, used in AFS are described. The limits of detection achieved up to the present, using flame and nonflame methods of atomization are given

Real-Time Wait-Free Queues using Micro-Transactions

DEFF Research Database (Denmark)

Meawad, Fadi; Iyer, Karthik; Schoeberl, Martin

2011-01-01

This paper evaluates the applicability of transactional mem- ory to the implementation of dierent non-blocking data structures in the context of the Real-time Specication for Java. In particular, we argue that hardware support for micro-transaction allows us to implement eciently data structures...... that are often dicult to realize with the atomic operations provided by stock hardware. Our main imple- mentation platform is the Java Optimized Processor sys- tem. We report on the performance of data structures imple- mented with locks, compare and swap and micro-transactions. Our results conrm...

Optically polarized atoms understanding light-atom interactions

CERN Document Server

Auzinsh, Marcis; Rochester, Simon M

2010-01-01

This book is addressed at upper-level undergraduate and graduate students involved in research in atomic, molecular, and optical Physics. It will also be useful to researchers practising in this field. It gives an intuitive, yet sufficiently detailed and rigorous introduction to light-atom interactions with a particular emphasis on the symmetry aspects of the interaction, especially those associated with the angular momentum of atoms and light. The book will enable readers to carryout practical calculations on their own, and is richly illustrated with examples drawn from current research topic

Relativistic Transitions in the Hydrogenic Atoms

CERN Document Server

Boudet, R

2009-01-01

When one approaches the study of the quantal relativistic theory of the electron, one may be surprised by the gap which lies between the frame of the experiments, i.e. the real geometry of the space and time, and the abstraction of the complex matrices and spinors formalism employed in the presentation of the theory. This book uses a theory of the electron, introduced by David Hestenes, in which the mathematical language is the same as the one of the geometry of the space and time. Such a language not only allows one to find again the well known results concerning the one-electron atoms theory but furthermore leads easily to the resolution of problems considered for a long time without solution.

Detection of Metabolic Fluxes of O and H Atoms into Intracellular Water in Mammalian Cells

Science.gov (United States)

Kreuzer, Helen W.; Quaroni, Luca; Podlesak, David W.; Zlateva, Theodora; Bollinger, Nikki; McAllister, Aaron; Lott, Michael J.; Hegg, Eric L.

2012-01-01

Metabolic processes result in the release and exchange of H and O atoms from organic material as well as some inorganic salts and gases. These fluxes of H and O atoms into intracellular water result in an isotopic gradient that can be measured experimentally. Using isotope ratio mass spectroscopy, we revealed that slightly over 50% of the H and O atoms in the intracellular water of exponentially-growing cultured Rat-1 fibroblasts were isotopically distinct from growth medium water. We then employed infrared spectromicroscopy to detect in real time the flux of H atoms in these same cells. Importantly, both of these techniques indicate that the H and O fluxes are dependent on metabolic processes; cells that are in lag phase or are quiescent exhibit a much smaller flux. In addition, water extracted from the muscle tissue of rats contained a population of H and O atoms that were isotopically distinct from body water, consistent with the results obtained using the cultured Rat-1 fibroblasts. Together these data demonstrate that metabolic processes produce fluxes of H and O atoms into intracellular water, and that these fluxes can be detected and measured in both cultured mammalian cells and in mammalian tissue. PMID:22848359

Decay of long-lived autoionization atomic states in atom collisions

International Nuclear Information System (INIS)

Krakov, B.G.

1994-01-01

Radiationless decay of long-lived autoionization states of helium atoms in atom collisions is investigated. It is shown that the states may decay in atom collisions due to softening of the selection rules

Hot atom chemistry of monovalent atoms in organic condensed phases

International Nuclear Information System (INIS)

Stoecklin, G.

1975-01-01

The advantages and disadvantages of hot atom studies in condensed organic phases are considered, and recent advances in condensed phase organic hot atom chemistry of recoil tritium and halogen atoms are discussed. Details are presented of the present status and understanding of liquid phase hot atom chemistry and also that of organic solids. The consequences of the Auger effect in condensed organic systems are also considered. (author)

Ab initio calculation atomics ground state wave function for interactions Ion- Atom

International Nuclear Information System (INIS)

Shojaee, F.; Bolori zadeh, M. A.

2007-01-01

Ab initio calculation atomics ground state wave function for interactions Ion- Atom Atomic wave function expressed in a Slater - type basis obtained within Roothaan- Hartree - Fock for the ground state of the atoms He through B. The total energy is given for each atom.

Finite-temperature stress calculations in atomic models using moments of position

Science.gov (United States)

Parthasarathy, Ranganathan; Misra, Anil; Ouyang, Lizhi

2018-07-01

Continuum modeling of finite temperature mechanical behavior of atomic systems requires refined description of atomic motions. In this paper, we identify additional kinematical quantities that are relevant for a more accurate continuum description as the system is subjected to step-wise loading. The presented formalism avoids the necessity for atomic trajectory mapping with deformation, provides the definitions of the kinematic variables and their conjugates in real space, and simplifies local work conjugacy. The total work done on an atom under deformation is decomposed into the work corresponding to changing its equilibrium position and work corresponding to changing its second moment about equilibrium position. Correspondingly, we define two kinematic variables: a deformation gradient tensor and a vibration tensor, and derive their stress conjugates, termed here as static and vibration stresses, respectively. The proposed approach is validated using MD simulation in NVT ensembles for fcc aluminum subjected to uniaxial extension. The observed evolution of second moments in the MD simulation with macroscopic deformation is not directly related to the transformation of atomic trajectories through the deformation gradient using generator functions. However, it is noteworthy that deformation leads to a change in the second moment of the trajectories. Correspondingly, the vibration part of the Piola stress becomes particularly significant at high temperature and high tensile strain as the crystal approaches the softening limit. In contrast to the eigenvectors of the deformation gradient, the eigenvectors of the vibration tensor show strong spatial heterogeneity in the vicinity of softening. More importantly, the elliptic distribution of local atomic density transitions to a dumbbell shape, before significant non-affinity in equilibrium positions has occurred.

Thermal Casimir-Polder forces on a V-type three-level atom

Science.gov (United States)

Xu, Chen-Ran; Xu, Jing-Ping; Al-amri, M.; Zhu, Cheng-Jie; Xie, Shuang-Yuan; Yang, Ya-Ping

2017-09-01

We study the thermal Casimir-Polder (CP) forces on a V-type three-level atom. The competition between the thermal effect and the quantum interference of the two transition dipoles on the force is investigated. To shed light onto the role of the quantum interference, we analyze two kinds of initial states of the atom, i.e., the superradiant state and the subradiant state. Considering the atom being in the thermal reservoir, the resonant CP force arising from the real photon emission dominates in the evolution of the CP force. Under the zero-temperature condition, the quantum interference can effectively modify the amplitude and the evolution of the force, leading to a long-time force or even the cancellation of the force. Our results reveal that in the finite-temperature case, the thermal photons can enhance the amplitude of all force elements, but have no influence on the net resonant CP force in the steady state, which means that the second law of thermodynamics still works. For the ideal degenerate V-type atom with parallel dipoles under the initial subradiant state, the robust destructive quantum interference overrides the thermal fluctuations, leading to the trapping of the atom in the subradiant state and the disappearance of the CP force. However, in terms of a realistic Zeeman atom, the thermal photons play a significant role during the evolution of the CP force. The thermal fluctuations can enhance the amplitude of the initial CP force by increasing the temperature, and weaken the influence of the quantum interference on the evolution of the CP force from the initial superradiant (subradiant) state to the steady state.

Pattern theory the stochastic analysis of real-world signals

CERN Document Server

Mumford, David

2010-01-01

Pattern theory is a distinctive approach to the analysis of all forms of real-world signals. At its core is the design of a large variety of probabilistic models whose samples reproduce the look and feel of the real signals, their patterns, and their variability. Bayesian statistical inference then allows you to apply these models in the analysis of new signals. This book treats the mathematical tools, the models themselves, and the computational algorithms for applying statistics to analyze six representative classes of signals of increasing complexity. The book covers patterns in text, sound

High speed real-time wavefront processing system for a solid-state laser system

Science.gov (United States)

Liu, Yuan; Yang, Ping; Chen, Shanqiu; Ma, Lifang; Xu, Bing

2008-03-01

A high speed real-time wavefront processing system for a solid-state laser beam cleanup system has been built. This system consists of a core2 Industrial PC (IPC) using Linux and real-time Linux (RT-Linux) operation system (OS), a PCI image grabber, a D/A card. More often than not, the phase aberrations of the output beam from solid-state lasers vary fast with intracavity thermal effects and environmental influence. To compensate the phase aberrations of solid-state lasers successfully, a high speed real-time wavefront processing system is presented. Compared to former systems, this system can improve the speed efficiently. In the new system, the acquisition of image data, the output of control voltage data and the implementation of reconstructor control algorithm are treated as real-time tasks in kernel-space, the display of wavefront information and man-machine conversation are treated as non real-time tasks in user-space. The parallel processing of real-time tasks in Symmetric Multi Processors (SMP) mode is the main strategy of improving the speed. In this paper, the performance and efficiency of this wavefront processing system are analyzed. The opened-loop experimental results show that the sampling frequency of this system is up to 3300Hz, and this system can well deal with phase aberrations from solid-state lasers.

High incidence of meningioma among Hiroshima atomic bomb survivors

International Nuclear Information System (INIS)

Shintani, Takahiro; Hayakawa, Norihiko; Hoshi, Masaharu

1999-01-01

Since the atomic bomb explosions in Hiroshima and Nagasaki, high incidences of leukemia, thyroid cancer and other tumors have been reported as atomic bomb-induced tumors. We investigated the incidence of meningioma among Hiroshima atomic bomb survivors. Sixty-eight patients surgically treated for meningioma who had been within 2.0 km of the hypocenter of the explosion were identified. Six hundred and seven non-exposed patients with meningioma were also studied. Treatment dates were from 1975 to 1992. The incidences of meningioma among 68 subjects within 2.0 km and 607 non-exposed patients were 8.7 and 3.0 cases per 10 5 persons per year, respectively. The incidences of meningioma among the survivors of Hiroshima in 5-year intervals since 1975 were 5.3, 7.4, 10.1, and 14.9, respectively. The incidences of meningioma classified by distances from the hypocenter of 1.5-2.0 km, 1.0-1.5 km and less than 1.0 km were 6.3, 7.6 and 20.0, respectively. The incidences of meningioma classified by doses to the brain of 0-0.099 Sv, 0.1-0.99 Sv and more than 1.0 Sv were 7.7, 9.2 and 18.2, respectively. The incidence of meningioma among Hiroshima atomic bomb survivors has increased since 1975. There was a significant correlation between the incidence and the dose of radiation to the brain. The present findings strongly suggest that meningioma is one of the tumors induced by atomic bombing in Hiroshima. (author)

Atomic switches: atomic-movement-controlled nanodevices for new types of computing

International Nuclear Information System (INIS)

Hino, Takami; Hasegawa, Tsuyoshi; Terabe, Kazuya; Tsuruoka, Tohru; Nayak, Alpana; Ohno, Takeo; Aono, Masakazu

2011-01-01

Atomic switches are nanoionic devices that control the diffusion of metal cations and their reduction/oxidation processes in the switching operation to form/annihilate a metal atomic bridge, which is a conductive path between two electrodes in the on-state. In contrast to conventional semiconductor devices, atomic switches can provide a highly conductive channel even if their size is of nanometer order. In addition to their small size and low on-resistance, their nonvolatility has enabled the development of new types of programmable devices, which may achieve all the required functions on a single chip. Three-terminal atomic switches have also been developed, in which the formation and annihilation of a metal atomic bridge between a source electrode and a drain electrode are controlled by a third (gate) electrode. Three-terminal atomic switches are expected to enhance the development of new types of logic circuits, such as nonvolatile logic. The recent development of atomic switches that use a metal oxide as the ionic conductive material has enabled the integration of atomic switches with complementary metal-oxide-semiconductor (CMOS) devices, which will facilitate the commercialization of atomic switches. The novel characteristics of atomic switches, such as their learning and photosensing abilities, are also introduced in the latter part of this review. (topical review)

Characterization of nanoparticles using Atomic Force Microscopy

International Nuclear Information System (INIS)

Rao, A; Schoenenberger, M; Gnecco, E; Glatzel, Th; Meyer, E; Braendlin, D; Scandella, L

2007-01-01

Nanoparticles are becoming increasingly important in many areas, including catalysis, biomedical applications, and information storage. Their unique size-dependent properties make these materials superior. Using the Atomic Force Microscope (AFM), individual particles and groups of particles can be resolved and unlike other microscopy techniques, the AFM offers visualization and analysis in three dimensions. We prepared titanium oxide, zirconium oxide and alumina nanoparticles and/or agglomerates on different surfaces and characterized them by AFM in the dynamic mode. The goal was to determine the shape, size and/or size distribution of nanoparticles. Different dilutions of nanoparticles were applied on various substrates e.g. clean silicon, mica and chemically treated silicon and imaged at ambient conditions. Nanoparticles deposited on mica appeared to be coagulated as compared to those on silicon. Whereas, on a chemically treated surface the density of the nanoparticles was very low because of the increased hydrophobicity of the surface

Atomic physics

International Nuclear Information System (INIS)

Anon.

1976-01-01

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 2 3 Po, 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 2 3 Po level of helium-like krypton

Hearts and Minds: Real-Life Cardiotoxicity With Clozapine in Psychosis.

Science.gov (United States)

Joy, George; Whiskey, Eromona; Bolstridge, Mark; Porras-Segovia, Alejandro; McDonagh, Theresa A; Plymen, Carla M; Shergill, Sukhi S

2017-12-01

Schizophrenia has a 1% prevalence in the population; 30% of these patients are treatment refractory. Clozapine is the only drug licensed to treat treatment refractory psychosis, but concerns about potential adverse effects result in only a proportion of eligible patients being treated. Although a well-documented neutropenia risk is mitigated by routine blood testing, cardiac toxicity is a commonly cited reason to discontinue clozapine treatment. However, there is little data on the real-life cardiac outcomes in those receiving clozapine treatment. Retrospective review of electrocardiogram, echocardiogram, and clinical outcomes in 39 inpatients with treatment-refractory schizophrenia, treated with clozapine and other antipsychotic medication, referred for cardiology opinion. Commonest reasons for referral were development of left ventricular (LV) impairment or sinus tachycardia with normal LV function. Patients were reviewed by a range of cardiologists, receiving varied interventions.Median LV ejection fraction in the clozapine group was normal (52%). Serial echocardiograms demonstrated that clozapine-treated patients with LV impairment had no change in LV ejection fraction over a 4-month follow-up. Left ventricular ejection fraction did not differ between patients treated with clozapine and other antipsychotics. However, over an 11-year follow-up period, 48% of patients had discontinued clozapine treatment. This naturalistic study demonstrates that clozapine is not associated with significant cardiac mortality or morbidity. There is a real need for multidisciplinary working between specialist cardiologists and psychiatrists caring for these complex patients to facilitate optimal long-term physical and mental health outcomes.

From a quantum to a classical description of intense laser-atom physics with Bohmian trajectories

International Nuclear Information System (INIS)

Lai, X Y; Cai Qingyu; Zhan, M S

2009-01-01

In this paper, Bohmian mechanics is applied to intense laser-atom physics. The motion of an atomic electron in an intense laser field is obtained from the Bohm-Newton equation. We find that the quantum potential that dominates the quantum effect of a physical system becomes negligible as the electron is driven far from the parent ion by the intense laser field, i.e. the behavior of the electron smoothly tends towards classical soon after the electron is ionized. Our numerical calculations present direct positive evidence for semiclassical trajectory methods in intense laser-atom physics where the motion of the ionized electron is treated by classical mechanics, while quantum mechanics is needed before the ionization.

Comparison of outcome in 1809 patients treated with drug-eluting stents or bare-metal stents in a real-world setting

Directory of Open Access Journals (Sweden)

Vogt A

2011-11-01

Full Text Available Alexander Vogt1, Anke Schoelmerich1, Franziska Pollner1, Manuela Schlitt1, Uwe Raaz1, Lars Maegdefessel2, Iris Reindl1, Michael Buerke1, Karl Werdan1, Axel Schlitt11Department of Medicine III, Martin Luther-University, Halle, Germany; 2Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USAPurpose: The aim of this study was to determine the long-term safety of drug-eluting stent (DES versus bare metal stent (BMS implantation in a “real-world” setting.Patients and methods: A total of 1809 patients who were treated with implantation of either BMS or DES were assessed. Kaplan-Meier and multivariate Cox regression analyses concerning primary endpoint of cardiac mortality were performed.Results: A total of 609 patients received DES. Mean age was 66.2 ± 11.3 years, 69.4% were male, and 1517 (83.8% were treated for acute coronary syndrome (unstable angina 510 [28.2%], non-ST-elevation myocardial infarction [NSTEMI] 506 [28.0%], and ST-elevation myocardial infarction [STEMI] 501 [27.7%]. Mean follow-up was 34 ± 15 months. During follow-up, 268 patients died of cardiac causes (DES 42 [7.3%]; BMS 226 [19.6%]; P < 0.001. Univariate Kaplan-Meier analysis showed an advantage of DES over BMS concerning the primary endpoint (P < 0.001. When adjusting for classic risk factors and additional factors that affect the progression of coronary heart disease (CHD, DES was not found to be superior to BMS (hazard ratio 0.996, 95% confidence interval 0.455–2.182, P = 0.993. Severely impaired renal function was an independent predictor for cardiac mortality after stent implantation.Conclusion: Treatment with DES is safe in the long term, also in patients presenting with STEMI. However, in multivariate analyses it is not superior to BMS treatment.Keywords: coronary stent, outcome, renal insufficiency, myocardial infarction, STEMI

Report of fact-finding survey for atomic energy in dustry, fiscal 1995

International Nuclear Information System (INIS)

1996-12-01

Japanese economy in fiscal year 1995 progressed with the tendency of gradual business recovery, and the real rate of economic growth was 2.4%. The final energy consumption has become the growth rate of 3.2% as compared with that in the previous year. Classifying by energy supply sources, the share of petroleum was 55.8% which was slight decrease, and nuclear power has become 12%, the highest so far. The share of coal was 16.5%, natural gas 10.8%, and water power 3.5%. Total supply of primary energy increased by 1.9%, and the demand of electric power increased by 1.6% as compared with those in the previous year. As for the circumstances of atomic energy industries in fiscal year 1995, the outlay related to atomic energy of electric power industry decreased sharply by about 13%, while the sales related to atomic energy of mining and manufacturing industries turned to the increase by about 5%. The outlay related to atomic energy of mining and manufacturing industries decreased by 8% as compared with that in the previous year. As the perspective for future, the outlay related to atomic energy of electric power industry is expected to increase. The total number of the persons who engage in private atomic energy enterprises was 60,540. The average capacity factor of 49 nuclear power plants in operation was 80.2%. The share of nuclear power taken in total generated electric power was 33.8%. Four nuclear power plants were under construction as of the end of fiscal year 1995. (K.I.)

Progress in atomic spectroscopy

International Nuclear Information System (INIS)

Beyer, H.J.; Kleinpoppen, H.

1984-01-01

This book presents reviews by leading experts in the field covering areas of research at the forefront of atomic spectroscopy. Topics considered include the k ordering of atomic structure, multiconfiguration Hartree-Fock calculations for complex atoms, new methods in high-resolution laser spectroscopy, resonance ionization spectroscopy (inert atom detection), trapped ion spectroscopy, high-magnetic-field atomic physics, the effects of magnetic and electric fields on highly excited atoms, x rays from superheavy collision systems, recoil ion spectroscopy with heavy ions, investigations of superheavy quasi-atoms via spectroscopy of electron rays and positrons, impact ionization by fast projectiles, and amplitudes and state parameters from ion- and atom-atom excitation processes

5. All-Russian (international) scientific conference. Physicochemical processes during selection of atoms and molecules. Collection of reports

International Nuclear Information System (INIS)

Baranov, V.Yu.; Kolesnikov, Yu.A.

2000-01-01

The materials of the 5. All-Russian (international) scientific conference: Physicochemical processes during selection of atoms and molecules, are presented. The conference took place in Zvenigorod, 2-6 October, 2000. A wide range of items connected with uranium enrichment, selection of atoms and molecules by isotopic composition: laser methods, ion cyclotron-resonance method, are discussed. The selection of molecules and atoms by rectification and chemical isotopic exchange methods, the selection in the field of centrifugal forces are treated. The questions of search for the new advanced methods for selection of atoms and molecules were discussed at the conference, the problems of radioisotope production were represented. The subject matter of the use of stable isotopes and radionuclides is demonstrated widely. The subjects connected with experimental and engineering equipment for selection of atoms and molecules are embodied in the paper [ru

Atomic reactor thermal engineering

International Nuclear Information System (INIS)

Kim, Gwang Ryong

1983-02-01

This book starts the introduction of atomic reactor thermal engineering including atomic reaction, chemical reaction, nuclear reaction neutron energy and soon. It explains heat transfer, heat production in the atomic reactor, heat transfer of fuel element in atomic reactor, heat transfer and flow of cooler, thermal design of atomic reactor, design of thermodynamics of atomic reactor and various. This deals with the basic knowledge of thermal engineering for atomic reactor.

Real space in situ bond energies: toward a consistent energetic definition of bond strength.

Science.gov (United States)

Menéndez-Crespo, Daniel; Costales, Aurora; Francisco, Evelio; Martin Pendas, Angel

2018-04-14

A rigorous definition of intrinsic bond strength based on the partitioning of a molecule into real space fragments is presented. Using the domains provided by the quantum theory of atoms in molecules (QTAIM) together with the interacting quantum atoms (IQA) energetic decomposition, we show how an in situ bond strength, matching all the requirements of an intrinsic bond energy, can be defined between each pair of fragments. Total atomization or fragmentation energies are shown to be equal to the sum of these in situ bond energies (ISBEs) if the energies of the fragments are measured with respect to their in-the-molecule state. These energies usually lie above the ground state of the isolated fragments by quantities identified with the standard fragment relaxation or deformation energies, which are also provided by the protocol. Deformation energies bridge dissociation energies with ISBEs, and can be dissected using well-known tools of real space theories of chemical bonding. Similarly, ISBEs can be partitioned into ionic and covalent contributions, and this feature adds to the chemical appeal of the procedure. All the energetic quantities examined are observable and amenable, in principle, to experimental determination. Several systems, exemplifying the role of each energetic term herein presented are used to show the power of the approach. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Atomically-resolved mapping of polarization and electric fields across ferroelectric-oxide interfaces by Z-contrast imaging

Science.gov (United States)

Borisevich, Albina; Chang, Hye Jung; Kalinin, Sergei; Morozovska, Anna; Chu, Ying-Hao; Yu, Pu; Ramesh, Ramamoorthy; Pennycook, Stephen

2011-03-01

Polarization, electric field, charge and potential across ferroelectric-oxide interfaces are obtained from direct atomic position mapping by aberration corrected scanning transmission electron microscopy combined with Ginsburg-Landau-Devonshire theory. We compare two antiparallel polarization orientations, which allows separation of the polarization and intrinsic interface charge contributions. Using the Born effective charges, the complete interface electrostatics is obtained in real space, providing an alternative method to holography. The results provide new microscopic insight into the thermodynamics of polarization distribution at the atomic level. Research is sponsored by the of Materials Sciences and Engineering Division, U.S. DOE.

X-ray fluorescence holography and multiple-energy x-ray holography: A critical comparison of atomic images

International Nuclear Information System (INIS)

Len, P.M.; Gog, T.; Fadley, C.S.; Materlik, G.

1997-01-01

We compare x-ray fluorescence holography (XFH) and multiple-energy x-ray holography (MEXH), two techniques that have recently been used to obtain experimental three-dimensional atomic images. For single-energy holograms, these methods are equivalent by virtue of the optical reciprocity theorem. However, XFH can only record holographic information at the characteristic fluorescence energies of the emitting species, while MEXH can record holographic information at any energy above the fluorescent edge of the emitter, thus enabling the suppression of real-twin overlaps and other aberrations and artifacts in atomic images. copyright 1997 The American Physical Society

Real-time analysis of water movement in plant sample

International Nuclear Information System (INIS)

Yokota, Harumi; Furukawa, Jun; Tanoi, Keitaro

2000-01-01

To know the effect of drought stress on two cultivars of cowpea, drought tolerant (DT) and drought sensitive (DS), and to estimate vanadium treatment on plant activity, we performed real time 18 F labeled water uptake measurement by PETIS. Fluoride-18 was produced by bombarding a cubic ice target with 50 MeV protons using TIARA AVF cyclotron. Then 18 F labeled water was applied to investigate water movement in a cowpea plant. Real time water uptake manner could be monitored by PETIS. After the analysis by PETIS, we also measured the distribution of 18 F in a whole plant by BAS. When a cowpea plant was treated with drought stress, there was a difference in water uptake manner between DT and DS cultivar. When a cowpea plant was treated with V for 20 hours before the water uptake experiment, the total amount of 18 F labeled water absorption was found to be drastically decreased. (author)

Real-time analysis of water movement in plant sample

Energy Technology Data Exchange (ETDEWEB)

Yokota, Harumi; Furukawa, Jun; Tanoi, Keitaro [Graduate School, Tokyo Univ. (Japan)

2000-07-01

To know the effect of drought stress on two cultivars of cowpea, drought tolerant (DT) and drought sensitive (DS), and to estimate vanadium treatment on plant activity, we performed real time{sup 18}F labeled water uptake measurement by PETIS. Fluoride-18 was produced by bombarding a cubic ice target with 50 MeV protons using TIARA AVF cyclotron. Then {sup 18}F labeled water was applied to investigate water movement in a cowpea plant. Real time water uptake manner could be monitored by PETIS. After the analysis by PETIS, we also measured the distribution of {sup 18}F in a whole plant by BAS. When a cowpea plant was treated with drought stress, there was a difference in water uptake manner between DT and DS cultivar. When a cowpea plant was treated with V for 20 hours before the water uptake experiment, the total amount of {sup 18}F labeled water absorption was found to be drastically decreased. (author)

Rapid prototyping of versatile atom chips for atom interferometry applications.

Science.gov (United States)

Kasch, Brian; Squires, Matthew; Olson, Spencer; Kroese, Bethany; Imhof, Eric; Kohn, Rudolph; Stuhl, Benjamin; Schramm, Stacy; Stickney, James

2016-05-01

We present recent advances in the manipulation of ultracold atoms with ex-vacuo atom chips (i.e. atom chips that are not inside to the UHV chamber). Details will be presented of an experimental system that allows direct bonded copper (DBC) atom chips to be removed and replaced in minutes, requiring minimal re-optimization of parameters. This system has been used to create Bose-Einstein condensates, as well as magnetic waveguides with precisely tunable axial parameters, allowing double wells, pure harmonic confinement, and modified harmonic traps. We investigate the effects of higher order magnetic field contributions to the waveguide, and the implications for confined atom interferometry.

First-Order Quantum Phase Transition for Dicke Model Induced by Atom-Atom Interaction

International Nuclear Information System (INIS)

Zhao Xiu-Qin; Liu Ni; Liang Jiu-Qing

2017-01-01

In this article, we use the spin coherent state transformation and the ground state variational method to theoretically calculate the ground function. In order to consider the influence of the atom-atom interaction on the extended Dicke model’s ground state properties, the mean photon number, the scaled atomic population and the average ground energy are displayed. Using the self-consistent field theory to solve the atom-atom interaction, we discover the system undergoes a first-order quantum phase transition from the normal phase to the superradiant phase, but a famous Dicke-type second-order quantum phase transition without the atom-atom interaction. Meanwhile, the atom-atom interaction makes the phase transition point shift to the lower atom-photon collective coupling strength. (paper)

Evolution Properties of Atomic Fidelity in the Combined Multi-Atom-Cavity Field System

International Nuclear Information System (INIS)

Wang Ju-Xia; Zhang Xiao-Juan; Zhang Xiu-Xing

2015-01-01

The atom fidelity is investigated in a system consisting of Mtwo-level atoms and M single-mode fields by use of complete quantum theory and numerical evaluation method. The influences of various system parameters on the evolution of atomic fidelity are studied. The results show that the atomic fidelity evolves in a Rabi oscillation manner. The oscillation frequency is mainly modulated by the coupling strength between atoms and light field, the atomic transition probabilities and the average photon numbers. Other factors hardly impact on the atomic fidelity. The present results may provide a useful approach to the maintenance of the atomic fidelity in the atom cavity field systems. (paper)

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.

Ubiquitous atom

International Nuclear Information System (INIS)

Spruch, G.M.; Spruch, L.

1974-01-01

The fundamentals of modern physics, including the basic physics and chemistry of the atom, elementary particles, cosmology, periodicity, and recent advances, are surveyed. The biology and chemistry of the life process is discussed to provide a background for considering the effects of atomic particles on living things. The uses of atomic power in space travel, merchant shipping, food preservation, desalination, and nuclear clocks are explored. (Pollut. Abstr.)

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

Energy Technology Data Exchange (ETDEWEB)

Arslan, Yasin [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Mehmet Akif Ersoy University, Faculty of Arts & Sciences, Chemistry Department, 15030 Burdur (Turkey); Musil, Stanislav; Matoušek, Tomáš; Kratzer, Jan [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic); Dědina, Jiří, E-mail: dedina@biomed.cas.cz [Institute of Analytical Chemistry of the ASCR, v. v. i., Veveří 97, 602 00 Brno (Czech Republic)

2015-01-01

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{sup −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{sup −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.

Electronic structure of atoms: atomic spectroscopy information system

International Nuclear Information System (INIS)

Kazakov, V V; Kazakov, V G; Kovalev, V S; Meshkov, O I; Yatsenko, A S

2017-01-01

The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists. (paper)

Electronic structure of atoms: atomic spectroscopy information system

Science.gov (United States)

Kazakov, V. V.; Kazakov, V. G.; Kovalev, V. S.; Meshkov, O. I.; Yatsenko, A. S.

2017-10-01

The article presents a Russian atomic spectroscopy, information system electronic structure of atoms (IS ESA) (http://grotrian.nsu.ru), and describes its main features and options to support research and training. The database contains over 234 000 records, great attention paid to experimental data and uniform filling of the database for all atomic numbers Z, including classified levels and transitions of rare earth and transuranic elements and their ions. Original means of visualization of scientific data in the form of spectrograms and Grotrian diagrams have been proposed. Presentation of spectral data in the form of interactive color charts facilitates understanding and analysis of properties of atomic systems. The use of the spectral data of the IS ESA together with its functionality is effective for solving various scientific problems and training of specialists.

Experimental atomic physics

International Nuclear Information System (INIS)

Anon.

1985-01-01

The experimental atomic physics program within the physics division is carried out by two groups, whose reports are given in this section. Work of the accelerator atomic physics group is centered around the 6.5-MV EN tandem accelerator; consequently, most of its research is concerned with atomic processes occurring to, or initiated by, few MeV/amu heavy ions. Other activities of this group include higher energy experiments at the Holifield Heavy Ion Research Facility (HHIRF), studies of electron and positron channeling radiation, and collaborative experiments at other institutions. The second experimental group concerns itself with lower energy atomic collision physics in support of the Fusion Energy Program. During the past year, the new Electron Cyclotron Resonance Source has been completed and some of the first data from this facility is presented. In addition to these two activities in experimental atomic physics, other chapters of this report describe progress in theoretical atomic physics, experimental plasma diagnostic development, and atomic data center compilation activities

Atom-atom interactions around the band edge of a photonic crystal waveguide.

Science.gov (United States)

Hood, Jonathan D; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E; Kimble, H J

2016-09-20

Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields [Formula: see text] outside the bandgap to localized fields [Formula: see text] within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the [Formula: see text] line of atomic cesium for [Formula: see text] atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode.

Atomic collisions research with excited atomic species

International Nuclear Information System (INIS)

Hoogerland, M.D.; Gulley, R.J.; Colla, M.; Lu, W.; Milic, D.; Baldwin, K.G.H.; Buckman, S.J.

1999-01-01

Measurements and calculations of fundamental atomic collision and spectroscopic properties such as collision cross sections, reaction rates, transition probabilities etc. underpin the understanding and operation of many plasma and gas-discharge-based devices and phenomena, for example plasma processing and deposition. In almost all cases the complex series of reactions which sustains the discharge or plasma, or produces the reactive species of interest, has a precursor electron impact excitation, attachment, dissociation or ionisation event. These processes have been extensively studied in a wide range of atomic and molecular species and an impressive data base of collision cross sections and reaction rates now exists. However, most of these measurements are for collisions with stable atomic or molecular species which are initially in their ground electronic state. Relatively little information is available for scattering from excited states or for scattering from unstable molecular radicals. Examples of such species would be metastable excited rare gases, which are often used as buffer gases, or CF 2 radicals formed by electron impact dissociation in a CF 4 plasma processing discharge. We are interested in developing experimental techniques which will enable the quantitative study of such exotic atomic and molecular species. In this talk I would like to outline one such facility which is being used for studies of collisions with metastable He(2 3 S) atoms

Experiments with Rydberg atoms on a current-carrying atom chip

NARCIS (Netherlands)

Cisternas San Martín, N.V.

2018-01-01

On one side, atom-chip experiments have demonstrated to be a versatile tool to study quantum physics in cold atoms systems. On the other side, Rydberg atoms have exaggerated properties that makes them good candidates to study quantum information and quantum simulations protocols. In this thesis both

Emotion Regulation Training for Training Warfighters with Combat Related PTSD Using Real Time fMRI and EEG Assisted Neurofeedback

Science.gov (United States)

2016-10-01

AWARD NUMBER: W81XWH-12-1-0607 TITLE: Emotion Regulation Training for Treating Warfighters with Combat-Related PTSD Using Real-Time fMRI...TYPE Annual 3. DATES COVERED 30 Sep 2015 - 29 Sep 2016 4. TITLE AND SUBTITLE Emotion Regulation Training for Treating Warfighters with Combat...emphasize dysregulation of the amygdala, which is involved in the regulation of PTSD-relevant emotions . We are utilizing real-time functional magnetic

Laser cooling of atoms and ions

International Nuclear Information System (INIS)

Morigi, G.

1999-02-01

introduction, which puts it into the context of the past and present scientific debate, and then the work itself which, in the cases where it has already appeared in a scientific journal, is presented in the form of the publication. More in detail, the introductory chapter deals first briefly with laser cooling of free atoms and then more comprehensively with laser cooling of trapped atoms, giving particular attention to the basic concepts and mechanisms which are recurrent throughout the rest of the thesis. At the end of the first chapter I give a discussion on the laser cooling of many atoms and ions, summarizing the state of the art and the applications currently under discussion, such as degenerate atomic gases and implementations of quantum information processing. The second and third chapters discuss schemes of laser cooling of single trapped atoms or ions to the motional ground state of a trap. These schemes are designed to be efficient in the regime where the amplitude of the particle's motion is comparable with the laser wavelength. In particular the scheme described in chapter II is a modification of sideband cooling and it considerably extends the efficiency of this technique to a wider range of trapping conditions. In chapter III a dark state cooling mechanism is presented, where the dark state is obtained in real space. Both schemes are demonstrated to be effective methods for preparing atoms in the ground state of a trapping potential. Chapter IV and chapter V focus on the problem of cooling more than one trapped ion, taking into account their Coulomb interaction, for trapping conditions which are typical for quantum information experiments. Chapter IV concentrates more on laser cooling to the ground state by means of sideband cooling, whereas in chapter V the theoretical problem of Doppler cooling of interacting trapped ions is discussed. (author)

Atom

International Nuclear Information System (INIS)

Auffray, J.P.

1997-01-01

The atom through centuries, has been imagined, described, explored, then accelerated, combined...But what happens truly inside the atom? And what are mechanisms who allow its stability? Physicist and historian of sciences, Jean-Paul Auffray explains that these questions are to the heart of the modern physics and it brings them a new lighting. (N.C.)

Entanglement dynamics between an isolated atom and a moving atom in the cavity

International Nuclear Information System (INIS)

Xiao-Juan, Deng; Mao-Fa, Fang; Guo-Dong, Kang

2009-01-01

The entanglement dynamics between an isolated atom and a moving atom interacting with a cavity field is investigated. The results show that there appears sudden death of entanglement between the isolated atom and the moving atom and that the time of entanglement sudden death (ESD) is independent of the initial state of the system. It is interesting that the isolated atom can also entangle with a cavity field, though they do not interact with each other originally, which stems from the fact that the entanglement between the isolated atom and the moving atom may turn into the entanglement between the isolated atom and the cavity. (general)

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...

Design and Construction of an Atomic Clock on an Atom Chip

International Nuclear Information System (INIS)

Reinhard, Friedemann

2009-01-01

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

Atomic switch: atom/ion movement controlled devices for beyond von-neumann computers.

Science.gov (United States)

Hasegawa, Tsuyoshi; Terabe, Kazuya; Tsuruoka, Tohru; Aono, Masakazu

2012-01-10

An atomic switch is a nanoionic device that controls the diffusion of metal ions/atoms and their reduction/oxidation processes in the switching operation to form/annihilate a conductive path. Since metal atoms can provide a highly conductive channel even if their cluster size is in the nanometer scale, atomic switches may enable downscaling to smaller than the 11 nm technology node, which is a great challenge for semiconductor devices. Atomic switches also possess novel characteristics, such as high on/off ratios, very low power consumption and non-volatility. The unique operating mechanisms of these devices have enabled the development of various types of atomic switch, such as gap-type and gapless-type two-terminal atomic switches and three-terminal atomic switches. Novel functions, such as selective volatile/nonvolatile, synaptic, memristive, and photo-assisted operations have been demonstrated. Such atomic switch characteristics can not only improve the performance of present-day electronic systems, but also enable development of new types of electronic systems, such as beyond von- Neumann computers. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Understanding the time dependence of atomic level populations in evolving plasmas

International Nuclear Information System (INIS)

Judge, Philip G.

2005-01-01

The time dependence of atomic level populations in evolving plasmas is studied using an eigenfunction expansion of the non-LTE rate equations. The work aims to develop understanding without the need for, and as an aid to, numerical solutions. The discussion is mostly limited to linear systems, especially those for optically thin plasmas, but the implicitly non-linear case of non-LTE radiative transfer is briefly discussed. Eigenvalue spectra for typical atomic systems are examined using results compiled by Hearon. Diagonal dominance and sign symmetry of rate matrices show that just one eigenvalue is zero (corresponding to the equilibrium state), that the remaining eigenvalues have negative real parts, and that oscillations, if any, are necessarily damped. Gershgorin's theorems are used to show that many eigenvalues are determined by the radiative lifetimes of certain levels, because of diagonal dominance. With other properties, this demonstrates the existence of both 'slow' and 'fast' time-scales, where the 'slow' evolution is controlled by properties of meta-stable levels. It is shown that, when collisions are present, Rydberg states contribute only 'fast' eigenvalues. This justifies use of the quasi-static approximation, in which atoms containing just meta-stable levels can suffice to determine the atomic evolution on time-scales long compared with typical radiative lifetimes. Analytic solutions for two- and three-level atoms are used to examine the basis of earlier intuitive ideas, such as the 'ionizing plasma' approximation. The power and limitations of Gershgorin's theorems are examined through examples taken from the solar atmosphere. The methods should help in the planning and interpretation of both experimental and numerical experiments in which atomic evolution is important. While the examples are astrophysical, the methods and results are applicable to plasmas in general

Chemical reactions of recoil atoms and thermal atoms of tritium with haloid benzenes

International Nuclear Information System (INIS)

Simirskij, Yu.N.; Firsova, L.P.

1978-01-01

Radiochemical yields have been determined for the products of substitution of hydrogen atoms and halides in Cl-, Br-, and I-benzenes with tritium atoms obtained during thermal dissociation of T 2 and with recoil atoms T arising in nuclear reaction 6 Li(n, P)T. It is shown that in the series of Cl-, Br-, and I-benzenes yields of the products of substitution of halides atoms with tritium grow, whereas those of hydrogen atom substitution change only little. The correlation nature of the yields of substitution products of halide atoms with tritium remains constant in a wide range of the initial kinetic energies of T atoms for the recoil atoms with E 0 =2.7 MeV and for the completely thermolized atoms during thermal dissociation of T 2

Atomic-absorption determination of tantalum and niobium in ore concentrates

International Nuclear Information System (INIS)

Elinson, S.V.; Korovin, Yu.I.; Kuchumov, V.A.

1975-01-01

A flame atom-absorption method was developed for determining tantalum and niobium at their level greater than 5% in Ta-Nb ore concentrates. Flame was produced by a nitrous oxide-acetylene mixture. The optimal composition of a buffer (3 mg/ml) of iron was determined by the method of factorial planning of the experiment and steep ascention by gradient. The optimizing parameter in factorial planning was obtained from the difference of optical densities of Ta and Nb, by taking the average value for two solutions which had dissimilar total composition and which imitated the real composition of the ore concentrates, i.e., the value of (ΔD/Dsub(av))sub(Ta) or (ΔD/Dsub(av))sub(Nb). The optimization of analytical conditions corresponded to the condition (ΔD/Dsub(av))→ 0, which indicated that the chosen optimizing parameter also facilitated the attainment of maximum D values. The variation coefficient in the determination of Ta and Nb was respectively 0.8 and 1.4%. There was a good agreement between the results obtained in Ta analysis by the atom-absorption and the extraction-gravimetric methods, and in Nb analysis by the atom-absorption, differential spectrophotometric and x-ray fluorescence methods

Atomic fountain and applications

International Nuclear Information System (INIS)

Rawat, H.S.

2000-01-01

An overview of the development of working of MOT along with the basic principle of laser atom cooling and trapping is given. A technique to separate the cooled and trapped atoms from the MOT using atomic fountain technique will also be covered. The widely used technique for atomic fountain is, first to cool and trap the neutral atoms in MOT and then launch them in the vertical direction, using moving molasses technique. Using 133 Cs atomic fountain clock, time improvement of 2 to 3 order of magnitude over a conventional 133 Cs atomic clock has been observed

Noise in strong laser-atom interactions: Phase telegraph noise

International Nuclear Information System (INIS)

Eberly, J.H.; Wodkiewicz, K.; Shore, B.W.

1984-01-01

We discuss strong laser-atom interactions that are subjected to jump-type (random telegraph) random-phase noise. Physically, the jumps may arise from laser fluctuations, from collisions of various kinds, or from other external forces. Our discussion is carried out in two stages. First, direct and partially heuristic calculations determine the laser spectrum and also give a third-order differential equation for the average inversion of a two-level atom on resonance. At this stage a number of general features of the interaction are able to be studied easily. The optical analog of motional narrowing, for example, is clearly predicted. Second, we show that the theory of generalized Poisson processes allows laser-atom interactions in the presence of random telegraph noise of all kinds (not only phase noise) to be treated systematically, by means of a master equation first used in the context of quantum optics by Burshtein. We use the Burshtein equation to obtain an exact expression for the two-level atom's steady-state resonance fluorescence spectrum, when the exciting laser exhibits phase telegraph noise. Some comparisons are made with results obtained from other noise models. Detailed treatments of the effects ofmly jumps, or as a model of finite laser bandwidth effects, in which the laser frequency exhibits random jumps. We show that these two types of frequency noise can be distinguished in light-scattering spectra. We also discuss examples which demonstrate both temporal and spectral motional narrowing, nonexponential correlations, and non-Lorentzian spectra. Its exact solubility in finite terms makes the frequency-telegraph noise model an attractive alternative to the white-noise Ornstein-Uhlenbeck frequency noise model which has been previously applied to laser-atom interactions

Generation of a slow and continuous cesium atomic beam for an atomic clock

International Nuclear Information System (INIS)

Park, Sang Eon; Lee, Ho Seong; Shin, Eun-joo; Kwon, Taeg Yong; Yang, Sung Hoon; Cho, Hyuck

2002-01-01

A thermal atomic beam from a cesium oven was slowed down by use of the Hoffnagle modified white-light cooling technique. In addition, the atomic beam was collimated by use of a two-dimensional optical molasses that was installed transverse to the atomic-beam direction. The flux of the atomic beam was 2x10 10 atoms/s, an increase of a factor of 16 as a result of the collimation. The mean longitudinal velocity was ∼24.4 m/s, and the rms velocity spread of the slowed atomic beam was ∼1 m/s. Compared with other methods, we found that the Hoffnagle method is suitable for the generation of slow atomic beams to be used in an atomic clock, which requires an ultralow magnetic field environment. This atomic beam was deflected by an angle of 30 deg. by a one-dimensional optical molasses to separate it from laser light and high-velocity atoms

Quality of life improvement in HIV-1 patients treated with raltegravir in a real-life observational study: RACING.

Science.gov (United States)

Spire, Bruno; Nait-Ighil, Lella; Pugliese, Pascal; Poizot-Martin, Isabelle; Jullien, Vincent; Marcelin, Anne-Geneviève; Billaud, Eric

2017-01-01

Good efficacy and safety of raltegravir in person living with HIV was demonstrated in clinical trials over five years, but real-life data, particularly about quality of life (QoL), are lacking. QoL was evaluated over time in adult patients first treated or switched to regimens containing raltegravir in an observational cohort study. Patient QoL was evaluated using the Fatigue Impact Scale (FIS) and the HIV Symptom Index (HSI). Data were collected at baseline and at 1, 3, 6, 12, 18, and 24 months. Baseline FIS and HSI subscores were compared with the scores at each visit using the paired Wilcoxon test. The impact of time, sociodemographic and medical variables upon patient-perceived fatigue and symptoms was also assessed using mixed multivariate models. From baseline, all FIS and HSI subscores improved significantly after one month of treatment. In addition, psychosocial FIS subscores and both the frequency of bothersome symptoms and HSI subscores improved significantly at each visit. Physical FIS subscores also improved significantly, except at month 18, whereas both cognitive and total FIS subscores improved only after 6 months and 24 months, respectively. In multivariate analysis, employment was independently associated over time with improved improvement in both FIS and HSI subscores. Patient QoL improved significantly over a 24-month period of treatment with a raltegravir-containing regimen. FIS and HSI are sensitive tools to measure the impact of new antiretroviral combinations on a patient's perception of QoL.

Atomic inner-shell physics

International Nuclear Information System (INIS)

Crasemann, B.

1985-01-01

This book discusses: relativistic and quantum electrodynamic effects on atomic inner shells; relativistic calculation of atomic transition probabilities; many-body effects in energetic atomic transitions; Auger Electron spectrometry of core levels of atoms; experimental evaluation of inner-vacancy level energies for comparison with theory; mechanisms for energy shifts of atomic K-X rays; atomic physics research with synchrotron radiation; investigations of inner-shell states by the electron energy-loss technique at high resolution; coherence effects in electron emission by atoms; inelastic X-ray scattering including resonance phenomena; Rayleigh scattering: elastic photon scattering by bound electrons; electron-atom bremsstrahlung; X-ray and bremsstrahlung production in nuclear reactions; positron production in heavy-ion collisions, and X-ray processes in heavy-ion collisions

Real-space description of semiconducting band gaps in substitutional systems

International Nuclear Information System (INIS)

Magri, R.; Zunger, A.

1991-01-01

The goal of ''band-gap engineering'' in substitutional lattices is to identify atomic configurations that would give rise to a desired value of the band gap. Yet, current theoretical approaches to the problems, based largely on compilations of band structures for various latice configurations, have not yielded simple rules relating structural motifs to band gaps. We show that the band gap of substitutional AlAs/GaAs lattices can be usefully expanded in terms of a hierarchy of contributions from real-space ''atomic figures'' (pairs, triplets, quadruplets) detemined from first-principles band-structure calculations. Pair figures (up to fourth neighbors) and three-body figures are dominant. In analogy with similar cluster expansions of the total energy, this permits a systematic search among all lattice configurations for those having ''special'' band gaps. This approach enables the design of substitutional systems with certain band-gap properties by assembling atomic figures. As an illustration, we predict that the [0 bar 12]-oriented (AlAs) 1 /(GaAs) 4 /(AlAs) 1 /(GaAs) 2 superlattice has the largest band gap among all Al 0.25 Ga 0.75 As lattices with a maximum of ten cations per unit cell

Platinum assay by neutron activation analysis and atomic absorption spectroscopy in cisplatin treated pregnant mice

International Nuclear Information System (INIS)

Esposito, M.; Collecchi, P.; Oddone, M.; Meloni, S.

1986-01-01

Cisplatin (CDDP) is an antineoplastic drug used in the treatment of a wide variety of tumors. This paper describes an investigation carried out on pregnant mice after intragastric or intraperitoneally treatment with CDDP from day 11 to 13 of gestation. Platinum content in different tissues, namely liver, kidney, placenta and brain, was determined at 18 day of pregnancy. Two analytical techniques were used, i.e. neutron activation analysis and atomic absorption spectroscopy. Results of both techniques are presented and discussed in terms of precision, accuracy and sensitivity. Neutron activation analysis appears to provide results better correlated with the drug treatment. (author)

Platinum assay by neutron activation analysis and atomic absorption spectroscopy in cisplatin treated pregnant mice

International Nuclear Information System (INIS)

Esposito, M.; Collecchi, P.; Oddone, M.; Meloni, S.

1987-01-01

Cisplatin (CDDP) is an antineoplastic drug used in the treatment of a wide variety of tumors. This paper describes an investigation carried out on pregnant mice after intragastric or intraperitoneal treatment with CDDP from the 11st to 13rd day of gestation. Platinum content in different liver, kidney, placenta and brain tissues, was determined at 18. day of pregnancy. Neutron activation analysis and atomic absorption spectroscopy were used. Results of both techniques are presented and discussed in terms of precision, accuracy and sensitivity. Neutron activation analysis appears to provide better results correlated with the drug treatment. (author) 10 refs.; 4 tables

Site determination of Ni atoms in Cu-Al-Ni shape memory alloys by electron channelling enhanced microanalysis

International Nuclear Information System (INIS)

Nakata, Yoshiyuki; Tadaki, Tsugio; Shimizu, Ken-ichi

1990-01-01

The crystallographic site of Ni atoms in the parent phase of differently heat-treated Cu-28.6Al-3.7Ni (at.%) shape memory alloys has been examined by electron channelling enhanced microanalysis (ALCHEMI) in order to clarify effects of heat-treatments on the Ni atom site and M s temperature. The heat-treatments were as follows: (a) Quenching into a 10% NaOH solution at 263 K, (b) Quenching into hot water at 363 K and (c) Aging at 523 K for 3.6 ks after treatment (b). The M s temperatures of specimens (a), (b) and (c) were 158, 185 and 259 K, respectively, increasing with lowering quenching rate or aging. ALCHEMI revealed that Ni atoms occupied an identical site in all the three kinds of specimens: The Ni atoms were located at the nearest neighbor sites around Al atoms. This preferential occupation of Ni atoms was attributed to the strong binding force between Ni and Al atoms. Thus, the change in M s temperature due to different heat-treatments was not directly related to the crystallographic site of Ni atoms, but might be caused by the ordering between the next nearest neighbor Cu and Al atoms. (author)

Effect of temperature on atom-atom collision chain length in metals

International Nuclear Information System (INIS)

Makarov, A.A.; Demkin, N.A.; Lyashchenko, B.G.

1981-01-01

Focused atom-atom collision chain lengths are calculated for fcc-crystals with account of thermal oscillations. The model of solid spheres with the Born-Merier potential has been used in the calculations. The dependence of chain lengths on the temperature, energy and movement direction of the first chain atom for Cu, Au, Ag, Pb, Ni is considered. The plot presented shows that the chain lengths strongly decrease with temperature growth, for example, for the gold at T=100 K the chain length equals up to 37 interatomic spacings, whereas at T=1000 K their length decreases down to 5 interatomic distances. The dependence of the energy loss by the chain atoms on the atom number in the chain is obtained in a wide range of crystal temperature and the primary chain atom energy [ru

Interpretation of atom probe tomography data for the intermetallic TiAl+Nb by means of field evaporation simulation

KAUST Repository

Boll, Torben

2013-01-01

In this paper simulations of the field evaporation process during field ion microscopy (FIM) and atom probe tomography (APT) are presented and compared with experimental data. The Müller-Schottky-model [1] was extended to include the local atomic arrangement on the evaporation process of atoms. This arrangement was described by the sum of the next-neighbor-binding-energies, which differ for an atom of type A, depending on how many A-A, B-B or A-B bonds are present. Thus simulations of APT-data of intermetallic phases become feasible. In this study simulations of L10-TiAl with additions of Nb are compared with experimental data. Certain artifacts, which appear for experimental data are treated as well. © 2012 Elsevier B.V.

Microfabricated Waveguide Atom Traps.

Energy Technology Data Exchange (ETDEWEB)

Jau, Yuan-Yu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-09-01

A nanoscale , microfabricated waveguide structure can in - principle be used to trap atoms in well - defined locations and enable strong photon-atom interactions . A neutral - atom platform based on this microfabrication technology will be prealigned , which is especially important for quantum - control applications. At present, there is still no reported demonstration of evanescent - field atom trapping using a microfabricated waveguide structure. We described the capabilities established by our team for future development of the waveguide atom - trapping technology at SNL and report our studies to overcome the technical challenges of loading cold atoms into the waveguide atom traps, efficient and broadband optical coupling to a waveguide, and the waveguide material for high - power optical transmission. From the atomic - physics and the waveguide modeling, w e have shown that a square nano-waveguide can be utilized t o achieve better atomic spin squeezing than using a nanofiber for first time.

Cold experiment of slag centrifugal granulation by rotary atomizer: Effect of atomizer configuration

International Nuclear Information System (INIS)

Wu, Jun-Jun; Wang, Hong; Zhu, Xun; Liao, Qiang; Li, Kai

2017-01-01

Centrifugal granulation has recently been employed to produce small blast furnace slag particles, so as to recover the waste heat from the high-temperature molten blast furnace slag. An appropriate atomizer enables centrifugal granulation to become a better cost-effective process for particle production. Thus, increasing emphasis has been placed on influence of atomizer configuration on granulation. In present study, three groups of atomizers were specially designed and the granulation performance of each atomizer was experimentally tested during cold experiments. The influences of atomizer configuration on granulation modes and droplet characteristics were investigated visually. Two modified correlations were proposed to predict the granulating droplet size by means of data fitting. The results indicated that the rotary cup atomizers can inhibit the film formation in contrast to rotary disc atomizer. Moreover, atomizers with outer angle of 90° was capable of producing smaller droplets. The revised correlation as well as the newly-developed correlation including the influence of atomizer configurations, presented in good agreement with the experiment data. In addition, an analysis on atomizer design was conducted to provide a good insight for industrialization. It was recommended to adopt cup-like atomizer in granulation for its ability to produce fine particles with smaller atomizer size.

Atom-atom interactions around the band edge of a photonic crystal waveguide

Science.gov (United States)

Hood, Jonathan D.; Goban, Akihisa; Asenjo-Garcia, Ana; Lu, Mingwu; Yu, Su-Peng; Chang, Darrick E.; Kimble, H. J.

2016-09-01

Tailoring the interactions between quantum emitters and single photons constitutes one of the cornerstones of quantum optics. Coupling a quantum emitter to the band edge of a photonic crystal waveguide (PCW) provides a unique platform for tuning these interactions. In particular, the cross-over from propagating fields E(x)∝e±ikxxE(x)∝e±ikxx outside the bandgap to localized fields E(x)∝e-κx|x|E(x)∝e-κx|x| within the bandgap should be accompanied by a transition from largely dissipative atom-atom interactions to a regime where dispersive atom-atom interactions are dominant. Here, we experimentally observe this transition by shifting the band edge frequency of the PCW relative to the D1D1 line of atomic cesium for N¯=3.0±0.5N¯=3.0±0.5 atoms trapped along the PCW. Our results are the initial demonstration of this paradigm for coherent atom-atom interactions with low dissipation into the guided mode.

Theoretical treatment of electron capture and excitation in two-electron system ion-atom, atom-atom collisions at low to intermediate energy

International Nuclear Information System (INIS)

Kimura, M.

1986-01-01

A review of various theoretical treatments which have been used to study electron-capture and excitation processes in two-electron-system ion-atom, atom-atom collisions at low to intermediate energy is presented. Advantages as well as limitations associated with these theoretical models in application to practical many-electron ion-atom, atom-atom collisions are specifically pointed out. Although a rigorous theoretical study of many-electron systems has just begun so that reports of theoretical calculations are scarce to date in comparison to flourishing experimental activities, some theoretical results are of great interest and provide important information for understanding collision dynamics of the system which contains many electrons. Selected examples are given for electron capture in a multiply charged ion-He collision, ion-pair formation in an atom-atom collision and alignment and orientation in a Li + + He collision. (Auth.)

Atom chip gravimeter

Science.gov (United States)

Schubert, Christian; Abend, Sven; Gebbe, Martina; Gersemann, Matthias; Ahlers, Holger; Müntinga, Hauke; Matthias, Jonas; Sahelgozin, Maral; Herr, Waldemar; Lämmerzahl, Claus; Ertmer, Wolfgang; Rasel, Ernst

2016-04-01

Atom interferometry has developed into a tool for measuring rotations [1], accelerations [2], and testing fundamental physics [3]. Gravimeters based on laser cooled atoms demonstrated residual uncertainties of few microgal [2,4] and were simplified for field applications [5]. Atomic gravimeters rely on the interference of matter waves which are coherently manipulated by laser light fields. The latter can be interpreted as rulers to which the position of the atoms is compared. At three points in time separated by a free evolution, the light fields are pulsed onto the atoms. First, a coherent superposition of two momentum states is produced, then the momentum is inverted, and finally the two trajectories are recombined. Depending on the acceleration the atoms experienced, the number of atoms detected in the output ports will change. Consequently, the acceleration can be determined from the output signal. The laser cooled atoms with microkelvin temperatures used in state-of-the-art gravimeters impose limits on the accuracy [4]. Therefore, ultra-cold atoms generated by Bose-Einstein condensation and delta-kick collimation [6,7] are expected to be the key for further improvements. These sources suffered from a low flux implying an incompatible noise floor, but a competitive performance was demonstrated recently with atom chips [8]. In the compact and robust setup constructed for operation in the drop tower [6] we demonstrated all steps necessary for an atom chip gravimeter with Bose-Einstein condensates in a ground based operation. We will discuss the principle of operation, the current performance, and the perspectives to supersede the state of the art. The authors thank the QUANTUS cooperation for contributions to the drop tower project in the earlier stages. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM

Algebraic and computational aspects of real tensor ranks

CERN Document Server

Sakata, Toshio; Miyazaki, Mitsuhiro

2016-01-01

This book provides comprehensive summaries of theoretical (algebraic) and computational aspects of tensor ranks, maximal ranks, and typical ranks, over the real number field. Although tensor ranks have been often argued in the complex number field, it should be emphasized that this book treats real tensor ranks, which have direct applications in statistics. The book provides several interesting ideas, including determinant polynomials, determinantal ideals, absolutely nonsingular tensors, absolutely full column rank tensors, and their connection to bilinear maps and Hurwitz-Radon numbers. In addition to reviews of methods to determine real tensor ranks in details, global theories such as the Jacobian method are also reviewed in details. The book includes as well an accessible and comprehensive introduction of mathematical backgrounds, with basics of positive polynomials and calculations by using the Groebner basis. Furthermore, this book provides insights into numerical methods of finding tensor ranks through...

Real estate valuation in the Republic of Serbia

Directory of Open Access Journals (Sweden)

Božić Branko S.

2014-01-01

Full Text Available There is no complete and systemized infrastructure for efficient and reliable evaluation of real estates in the Republic of Serbia. This is confirmed by analysis of the applicable regulations which treat valuation of real estates in different ways. This practice contradicting numerous standards and applicable directives (INSPIRE directive, Strategy of the development of geospatial data infrastructure in the Republic of Serbia etc., as well as numerous other examples of good practice governing the activities of collecting and maintaining spatial data infrastructure. By the Law on State Survey and Cadaster of the 2009, the Republic Geodetic Authority is ensured to the jurisdiction of the development of mass appraisal, which should provide real estate market value for all real estates in the territory of the Republic of Serbia. In contrast, the position and the role of local government being increasable stronger in creating the budget, which is closely associated with the values of resources and capital which local government have. Determing the property tax is the responsibility of the local government and therefore its role in the process of valuation of immovable property is of great importance. In addition to local governments, the Tax Administration traditionally determines real estate values. This paper analyzes the current situation and initiate further activities on the development of the system of evaluation of real estates in the Republic of Serbia.

Observation of atomic arrangement by using photoelectron holography and atomic stereo-photograph

International Nuclear Information System (INIS)

Matsushita, Tomohiro; Guo, Fang Zhun; Agui, Akane; Matsui, Fumihiko; Daimon, Hiroshi

2006-01-01

Both a photoelectron holography and atomic stereo-photograph are the atomic structure analysis methods on the basis of photoelectron diffraction. They have six special features such as 1) direct determination of atomic structure, 2) measurement of three dimensional atomic arrangements surrounding of specific element in the sample, 3) determination of position of atom in spite of electron cloud, 4) unnecessary of perfect periodic structure, 5) good sensitivity of structure in the neighborhood of surface and 6) information of electron structure. Photoelectron diffraction, the principle and measurement system of photoelectron holography and atomic stereo-photograph is explained. As application examples of atomic stereo-photograph, the single crystal of cupper and graphite are indicated. For examples of photoelectron holography, Si(001)2p and Ge(001)3s are explained. (S.Y.)

Review of Real-Time 3-Dimensional Image Guided Radiation Therapy on Standard-Equipped Cancer Radiation Therapy Systems: Are We at the Tipping Point for the Era of Real-Time Radiation Therapy?

Science.gov (United States)

Keall, Paul J; Nguyen, Doan Trang; O'Brien, Ricky; Zhang, Pengpeng; Happersett, Laura; Bertholet, Jenny; Poulsen, Per R

2018-04-14

To review real-time 3-dimensional (3D) image guided radiation therapy (IGRT) on standard-equipped cancer radiation therapy systems, focusing on clinically implemented solutions. Three groups in 3 continents have clinically implemented novel real-time 3D IGRT solutions on standard-equipped linear accelerators. These technologies encompass kilovoltage, combined megavoltage-kilovoltage, and combined kilovoltage-optical imaging. The cancer sites treated span pelvic and abdominal tumors for which respiratory motion is present. For each method the 3D-measured motion during treatment is reported. After treatment, dose reconstruction was used to assess the treatment quality in the presence of motion with and without real-time 3D IGRT. The geometric accuracy was quantified through phantom experiments. A literature search was conducted to identify additional real-time 3D IGRT methods that could be clinically implemented in the near future. The real-time 3D IGRT methods were successfully clinically implemented and have been used to treat more than 200 patients. Systematic target position shifts were observed using all 3 methods. Dose reconstruction demonstrated that the delivered dose is closer to the planned dose with real-time 3D IGRT than without real-time 3D IGRT. In addition, compromised target dose coverage and variable normal tissue doses were found without real-time 3D IGRT. The geometric accuracy results with real-time 3D IGRT had a mean error of real-time 3D IGRT methods using standard-equipped radiation therapy systems that could also be clinically implemented. Multiple clinical implementations of real-time 3D IGRT on standard-equipped cancer radiation therapy systems have been demonstrated. Many more approaches that could be implemented were identified. These solutions provide a pathway for the broader adoption of methods to make radiation therapy more accurate, impacting tumor and normal tissue dose, margins, and ultimately patient outcomes. Copyright © 2018

Atom dynamics in laser fields

International Nuclear Information System (INIS)

Jang, Su; Mi, No Gin

2004-12-01

This book introduces coherent dynamics of internal state, spread of atoms wave speed, semiclassical atoms density matrix such as dynamics equation in both still and moving atoms, excitation of atoms in movement by light, dipole radiating power, quantum statistical mechanics by atoms in movement, semiclassical atoms in movement, atoms in movement in the uniform magnetic field including effects of uniform magnetic field, atom cooling using laser such as Doppler cooling, atom traps using laser and mirrors, radiant heat which particles receive, and near field interactions among atoms in laser light.

prepared via atom transfer radical polymerization, reverse atom

Indian Academy of Sciences (India)

Synthesis and characterization of poly(2-ethylhexyl acrylate) prepared via atom transfer radical polymerization, reverse atom transfer radical polymerization and ... Zydex Industries, 25-A Gandhi Oil Mill Compound, Gorwa, Vadodara 390 016, India; Rubber Technology Centre, Indian Institute of Technology Kharagpur, ...

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...

Quality assurance test of a real time radiography system

International Nuclear Information System (INIS)

Yadav, R.K.; Rama, R.; Sharma, A.; Kannan, R.

2005-01-01

Any radiation generating equipment can be used and marketed in India only after obtaining specific type approval certificate from the Competent Authority i.e. Chairman, Atomic Energy Regulatory Board (AERB), Mumbai. Recently AERB has enforced a directive that the Industrial X-ray machines should also be permitted to use only after getting NOC or type approval. Type approval is granted based upon the satisfactory QA test report of the radiation generating equipment. X-ray machines with Real Time Radiography (RTR) facility are used in industrial radiography for faster inspection of equipment's and products online. A standard test protocol was developed for QA tests of a real time radiography system. This will be helpful for evaluation of an industrial X-ray machine. Also above procedure can be used to check a RTR system each day or a system-qualification can be done when the image quality diminishes as recommended by American Society of Testing Material (ASTM). Various tests carried out on a constant potential 450 kV, 10 mA industrial X-ray machine having real time radiography facility to monitor the products online, is described in this paper. (author)

Tunneling couplings in discrete lattices, single-particle band structure, and eigenstates of interacting atom pairs

International Nuclear Information System (INIS)

Piil, Rune; Moelmer, Klaus

2007-01-01

By adjusting the tunneling couplings over longer than nearest-neighbor distances, it is possible in discrete lattice models to reproduce the properties of the lowest energy band of a real, continuous periodic potential. We propose to include such terms in problems with interacting particles, and we show that they have significant consequences for scattering and bound states of atom pairs in periodic potentials

Mechanism of formation and spatial distribution of lead atoms in quartz tube atomizers

Science.gov (United States)

Johansson, M.; Baxter, D. C.; Ohlsson, K. E. A.; Frech, W.

1997-05-01

The cross-sectional and longitudinal spatial distributions of lead atoms in a quartz tube (QT) atomizers coupled to a gas chromatograph have been investigated. A uniform analyte atom distribution over the cross-section was found in a QT having an inner diameter (i.d.) of 7 mm, whereas a 10 mm i.d. QT showed an inhomogeneous distribution. These results accentuate the importance of using QTs with i.d.s below 10 mm to fulfil the prerequirement of the Beer—Lambert law to avoid bent calibration curves. The influence of the make up gas on the formation of lead atoms from alkyllead compounds has been studied, and carbon monoxide was found equally efficient in promoting free atom formation as hydrogen. This suggests that hydrogen radicals are not essential for mediating the atomization of alkyllead in QT atomizers at ˜ 1200 K. Furthermore, thermodynamic equilibrium calculations describing the investigated system were performed supporting the experimental results. Based on the presented data, a mechanism for free lead atom formation in continuously heated QT atomizers is proposed; thermal atomization occurs under thermodynamic equilibrium conditions in a reducing gas. The longitudinal atom distribution has been further investigated applying other make up gases, N 2 and He. These results show the effect of the influx of atmospheric oxygen on the free lead atom formation. Calculations of the partial pressure of oxygen in the atomizer gas phase assuming thermodynamic equilibrium have been undertaken using a convective-diffusional model.

Web Supplement to "Teaching Chain-Weight Real GDP Measures."

Science.gov (United States)

Cahill, Miles B.

2003-01-01

Describes a Web site that is a companion to the Miles Cahill article, "Teaching Chain-Weight Real GDP Measures." States that the exercises are useful because intermediate level textbooks treat this topic casually. Indicates that the Web site contains the comment tool, an overview of the concepts, and links to article references. (JEH)

Modern atomic physics

CERN Document Server

Natarajan, Vasant

2015-01-01

Much of our understanding of physics in the last 30-plus years has come from research on atoms, photons, and their interactions. Collecting information previously scattered throughout the literature, Modern Atomic Physics provides students with one unified guide to contemporary developments in the field. After reviewing metrology and preliminary material, the text explains core areas of atomic physics. Important topics discussed include the spontaneous emission of radiation, stimulated transitions and the properties of gas, the physics and applications of resonance fluorescence, coherence, cooling and trapping of charged and neutral particles, and atomic beam magnetic resonance experiments. Covering standards, a different way of looking at a photon, stimulated radiation, and frequency combs, the appendices avoid jargon and use historical notes and personal anecdotes to make the topics accessible to non-atomic physics students. Written by a leader in atomic and optical physics, this text gives a state-of-the...

Combined impact of quorum quenching and backwashing on biofouling control in a semi-pilot scale mbr treating real wastewater

International Nuclear Information System (INIS)

Hasnain, G.; Khan, S.J.; Arshad, M.Z.; Abdullah, H.Y.

2017-01-01

This study demonstrates the combined effect of quorum quenching (QQ) and backwashing on biofouling control in MBR treating real wastewater. The quorum quenching mechanism is an emerging biological technique using Rhodococcus sp. entrapped in polymer coated sodium alginate beads whereas, backwashing is a distinguished physical technique for biofouling control. Two parallel semi-pilot scale MBRs i.e., QQ-MBR (quorum quenching MBR) with cell-entrapping beads (CEBs) and C-MBR (conventional MBR) with vacant CEBs at 0.5% effective volume of the bioreactor, were monitored for comparative performance evaluation. In the first phase, both the MBRs were operated without backwashing having operational cycle of eight min filtration and two min relaxation and in the second phase; MBRs were operated with backwashing having operation cycle of eight min filtration, one min relaxation and one min backwashing. QQ-MBR-with backwashing exhibited greater biofouling control capability and elongated filtration duration with respect to QQ-MBR without backwashing. Comparatively less soluble EPS concentrations were detected in QQ-MBR as compare to C-MBR in both modes of operation while backwashing contributed to retard the rapid increase in trans-membrane pressure (TMP) also known as TMP jump. Study reveals the novelty of successful application of combined influence of permeate backflushing technique and QQ (anti-biofouling) strategy in MBR and potential use for full scale applications. (author)

Observations of crystallization and melting in poly(ethylene oxide)/poly(methyl methacrylate) blends by hot-stage atomic-force microscopy

NARCIS (Netherlands)

Pearce, R.; Vancso, Gyula J.

1998-01-01

The binary blend of poly(ethylene oxide)/atactic poly(methyl methacrylate) is examined using hot-stage atomic-force microscopy (AFM) in conjunction with differential scanning calorimetry and optical microscopy. It was found possible to follow in real time the melting process, which reveals itself to

0.75 atoms improve the clock signal of 10,000 atoms

DEFF Research Database (Denmark)

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

2017-01-01

Since the pioneering work of Ramsey, atom interferometers are employed for precision metrology, in particular to measure time and to realize the second. In a classical interferometer, an ensemble of atoms is prepared in one of the two input states, whereas the second one is left empty. In this case.......75 atoms to improve the clock sensitivity of 10,000 atoms by 2.05 dB. The SQL poses a significant limitation for today's microwave fountain clocks, which serve as the main time reference. We evaluate the major technical limitations and challenges for devising a next generation of fountain clocks based...... on atomic squeezed vacuum....

Atomic effects in tritium beta-decay. II. Muon to electron conversion in atoms

International Nuclear Information System (INIS)

Wampler, K.D.

1989-01-01

I. The final-state, atomic effects in the low energy end of the tritium beta decay spectrum are studied in detail. The author treats the instantaneous, two-electron repulsion in the final state, effectively to all orders in perturbation theory, by solving the eigenvalue problem with a discretized and truncated form of the Hamiltonian. He finds that these effects fail to explain the distortion in the spectrum observed by Simpson (Phys. Rev. Lett. 54, 649 (1985)). Simpson attributed this distortion to the admixture of a heavy mass antineutrino in the outgoing electron antineutrino state. In fact, the final-state Coulomb effects enhance the distortion. This calculation clears up some of the ambiguities of other theoretical analyses based on considerations of screening functions and perturbation theory. II. He presents a phenomenological study of separate lepton number violating muon to electron conversion in atoms. Previous work on this process has concentrated on elastic transitions where the nucleus characteristics have the gate on the substrate and the source-drain contacts on the top of the sample. The first use as an FET dielectric is reported of hydrogenated amorphous silicon-carbon (prepared from silane and propane mixture), photo-oxidised by UV lamp or laser. These FETs have similar characteristics to those with silicon nitride gate insulator but without the difficulties of preparing good insulator/semiconductor interfaces. Using the same materials attempts have been made to produce charge coupled devices

Multipolar electrostatics for proteins: atom-atom electrostatic energies in crambin.

Science.gov (United States)

Yuan, Yongna; Mills, Matthew J L; Popelier, Paul L A

2014-02-15

Accurate electrostatics necessitates the use of multipole moments centered on nuclei or extra point charges centered away from the nuclei. Here, we follow the former alternative and investigate the convergence behavior of atom-atom electrostatic interactions in the pilot protein crambin. Amino acids are cut out from a Protein Data Bank structure of crambin, as single amino acids, di, or tripeptides, and are then capped with a peptide bond at each side. The atoms in the amino acids are defined through Quantum Chemical Topology (QCT) as finite volume electron density fragments. Atom-atom electrostatic energies are computed by means of a multipole expansion with regular spherical harmonics, up to a total interaction rank of L = ℓA+ ℓB + 1 = 10. The minimum internuclear distance in the convergent region of all the 15 possible types of atom-atom interactions in crambin that were calculated based on single amino acids are close to the values calculated from di and tripeptides. Values obtained at B3LYP/aug-cc-pVTZ and MP2/aug-cc-pVTZ levels are only slightly larger than those calculated at HF/6-31G(d,p) level. This convergence behavior is transferable to the well-known amyloid beta polypeptide Aβ1-42. Moreover, for a selected central atom, the influence of its neighbors on its multipole moments is investigated, and how far away this influence can be ignored is also determined. Finally, the convergence behavior of AMBER becomes closer to that of QCT with increasing internuclear distance. Copyright © 2013 Wiley Periodicals, Inc.

Antiprotonic-hydrogen atoms

International Nuclear Information System (INIS)

Batty, C.J.

1989-07-01

Experimental studies of antiprotonic-hydrogen atoms have recently made great progress following the commissioning of the low energy antiproton facility (LEAR) at CERN in 1983. At the same time our understanding of the atomic cascade has increased considerably through measurements of the X-ray spectra. The life history of the p-bar-p atom is considered in some detail, from the initial capture of the antiproton when stopping in hydrogen, through the atomic cascade with the emission of X-rays, to the final antiproton annihilation and production of mesons. The experiments carried out at LEAR are described and the results compared with atomic cascade calculations and predictions of strong interaction effects. (author)

Improved stability of OLEDs with mild oxygen plasma treated PEDOT:PSS

International Nuclear Information System (INIS)

Zhou Yunfei; Yuan Yongbo; Cao Lingfang; Zhang Jie; Pang Hongqi; Lian Jiarong; Zhou Xiang

2007-01-01

We demonstrate improved stability of OLEDs with mild oxygen plasma-treated poly (3,4-ethylenedioxythiophene) doped with poly (styrenesulfonate) (PEDOT:PSS) as anode buffer layer. The devices with treated PEDOT:PSS layer exhibited dramatically enhanced lifetime by a factor of 9 compared to the control devices. We investigated the substantial changes in surface morphology of PEDOT:PSS layer after the mild oxygen plasma treatment by scanning electron microscopy and atomic force microscopy. We found that the appropriate treatment can form uniformly distributed nano scaled hillocks/islands on the surface of PEDOT:PSS layer, which possibly result in improved contact to hole transport layer and thus enhanced lifetime of the devices

Depth of origin of sputtered atoms: Experimental and theoretical study of Cu/Ru(0001)

International Nuclear Information System (INIS)

Burnett, J.W.; Biersack, J.P.; Gruen, D.M.; Joergensen, B.; Krauss, A.R.; Pellin, M.J.; Schweitzer, E.L.; Yates, J.T. Jr.; Young, C.E.

1987-01-01

The depth of origin of sputtered atoms is a subject of considerable interest. The surface sensitivity of analytical techniques such as Secondary Ion Mass Spectrometry (SIMS) and Surface Analysis by Resonance Ionization of Sputtered Atoms (SARISA), and the sputtering properties of strongly segregating alloy systems, are critically dependent on the sputtering depth of origin. A significant discrepancy exists between the predictions of the Sigmund theory and computer sputtering models; in general, the computer models predict a much shallower depth of origin. The existing experimental evidence suggests that most of the sputtered atoms originate in the topmost atomic layer, but until recently, the results have not been definitive. We have experimentally determined the depth of origin of atoms sputtered from surfaces consisting of Cu films of less than two monolayers on a Ru(0001) substrate. The Cu/Ru target was statically sputtered using 3.6 keV Ar + . The sputtered neutrals were non-resonantly laser ionized and detected using SARISA. The Cu/Ru sputtering yield ratio and the suppression of the Ru sputtering yield were determined for various Cu coverages. The results indicate that the majority of the sputtered atoms originate in the topmost atomic layer. The Cu/Ru system is also modeled using a modified Transport of Ions in Matter (TRIM) code. It was found that TRIM C does not correctly treat the first atomic layer, resulting in a serious underestimate of the number of sputtered atoms which originate in this layer. The corrected version adequately describes the results, predicting that for the experimental conditions roughly two-thirds of the sputtered atoms originate in the first atomic layer. These results are significantly greater than the Sigmund theory estimate of >40%. 26 refs., 3 figs., 1 tab

Atomic resonances above the total ionization energy

International Nuclear Information System (INIS)

Doolen, G.

1975-01-01

A rigorous result obtained using the theory associated with dilatation analytic potentials is that by performing a complex coordinate rotation, r/subj/ → r/subj/e/subi//sup theta/, on a Hamiltonian whose potential involves only pairwise Coulombic interactions, one can show that when theta = π/2, no complex eigenvalues (resonances) appear whose energies have a real part greater than the total ionization energy of the atomic system. This appears to conflict with experimental results of Walton, Peart, and Dolder, who find resonance behavior above the total ionization energy of the H -- system and also the theoretical stabilization results of Taylor and Thomas for the same system. A possible resolution of this apparent conflict is discussed and a calculation to check its validity is proposed

2nd International School of Physics of Exotic Atoms "Ettore Majorana"

CERN Document Server

Duclos, J; Fiorentini, Giovanni; Torelli, Gabriele; Exotic atoms : fundamental interactions and structure of matter

1980-01-01

The second course of the International School on the Physics of Exotic Atoms took place at the "Ettore Majorana" Center for Scien­ tific Culture, Erice, Sicily, during the period from March 25 to April 5, 1979. It was attended by 40 participants from 23 insti­ tutes in 8 countries. The purpose of the course was to review the various aspects of the physics of exotic atoms, with particular emphasis on the re­ sults obtained in the last two years, i.e., after the first course of the School (Erice, April 24-30, 1977). The course dealt with two main topics, A) Exotic atoms and fundamental interactions and B) Applications to the study of the structure of matter. One of the aims of the course was to offer an opportunity for the exchange of experiences between scientists working in the two fields. In view of this, the lectures in the morning discussed the more general arguments in a common session, whereas the more specialized topics were treated in the afternoon, in two parallel sections. Section A was or...

A three-dimensional relaxation model for calculation of atomic mixing and topography changes induces by ion beams

International Nuclear Information System (INIS)

Collins, R.; Perez-Martin, A.M.C.; Dominguez-Vazquez, J.; Jimenez-Rodriguez, J.J.

1994-01-01

A simple model for three-dimensional material relaxation associated with atomic mixing is presented. The relaxation of the solid to accommodate the extra effective displacement volume Ω of an implanted or relocated atom is modelled by treating the surrounding solid as an incompressible medium. This leads to a tractable general formalism which can be used to predict implant distribution and changes in surface topography induced by ion beams, both in monatomic and multicomponent targets. The two-component case is discussed in detail. (orig.)

7,528 patients treated with PCI - a Scandinavian real-life scenario

DEFF Research Database (Denmark)

Pedersen, S.; Galatius, S.; Bech, J.

2008-01-01

AIM: Analyze clinical, temporal and procedural characteristics from 7,528 consecutive percutaneous coronary intervention (PCI) patients in one of the largest published contemporary European PCI-database during a 6-year period. METHOD: Retrospective study design. Period: 1998-2004. Temporal...... and referral changes in a Danish PCI-registry were analyzed. Demographic and angiographic variables were compared with data from randomized clinical trials, US-registries and current guidelines. RESULTS: 22,214 patients were examined with coronary angiography and 7,528 patients were treated with PCI....... The annual number of PCI's increased by 15%. Over time, the fraction of patients with risk factors increased, median age increased from 61 to 64 years and the coronary pathology was significantly worsened. ST-elevation myocardial infarction patients primarily admitted to hospitals without facilities...

Atoms - molecules - nuclei. Vol. 1

International Nuclear Information System (INIS)

Otter, G.; Honecker, R.

1993-01-01

This first volume covers the following topics: Wave-particle dualism, classical atomic physics; the Schroedinger equation, angular momentum in quantum physics, one-electron atoms and many-electron atoms with atomic structure, atomic spectra, exotic atoms, influence of electric and magnetic fields

Amplitudes and state parameters from ion- and atom-atom excitation processes

International Nuclear Information System (INIS)

Andersen, T.; Horsdal-Pedersen, E.

1984-01-01

This chapter examines single collisions between two atomic species, one of which is initially in a 1 S state (there is only one initial spin channel). The collisions are characterized by a definite scattering plane and a definite orientation. Topics considered include an angular correlation between scattered particles and autoionization electrons or polarized photons emitted from states excited in atomic collisions (photon emission, electron emission, selectivity excited target atoms), experimental methods for obtaining information on the alignment and orientation parameters of atoms or ions excited in specific collisions, results of experiments and numerical calculations (quasi-oneelectron systems, He + -He collisions, other collision systems), and future aspects and possible applications of the polarizedphoton, scattered-particle coincidence techniques to atomic spectroscopy

Unified quantum theory of elastic and inelastic atomic scattering from a physisorbed monolayer solid

DEFF Research Database (Denmark)

Bruch, L. W.; Hansen, Flemming Yssing; Dammann, Bernd

2017-01-01

A unified quantum theory of the elastic and inelastic scattering of low energy He atoms by a physisorbed monolayer solid in the one-phonon approximation is given. It uses a time-dependent wave packet with phonon creation and annihilation components and has a self-consistent feedback between...... the wave functions for elastic and inelastic scattered atoms. An attenuation of diffraction scattering by inelastic processes thus is inherent in the theory. The atomic motion and monolayer vibrations in the harmonic approximation are treated quantum mechanically and unitarity is preserved. The evaluation...... of specific one-phonon events includes contributions from diffuse inelastic scattering in other phonon modes. Effects of thermally excited phonons are included using a mean field approximation. The theory is applied to an incommensurate Xe/Pt(111) monolayer (incident energy Ei = 4-16 meV), a commensurate Xe...

‘Which-way’ collective atomic spin excitation among atomic ensembles by photon indistinguishability

International Nuclear Information System (INIS)

Zhang Guowan; Bian Chenglin; Chen, L Q; Ou, Z Y; Zhang Weiping

2012-01-01

In spontaneous Raman scattering in an atomic ensemble, a collective atomic spin wave is created in correlation with the Stokes field. When the Stokes photons from two or more such atomic ensembles are made indistinguishable, a ‘which-way’ collective atomic spin excitation is generated among the independent atomic ensembles. We demonstrate this phenomenon experimentally by reading out the atomic spin excitations and observing interference between the read-out beams. When a single-photon projective measurement is made on the indistinguishable Stokes photons, this simple scheme can be used to entangle independent atomic ensembles. Compared to other currently used methods, this scheme can be easily scaled up and has greater efficiency. (paper)

Clarifying atomic weights: A 2016 four-figure table of standard and conventional atomic weights

Science.gov (United States)

Coplen, Tyler B.; Meyers, Fabienne; Holden, Norman E.

2017-01-01

To indicate that atomic weights of many elements are not constants of nature, in 2009 and 2011 the Commission on Isotopic Abundances and Atomic Weights (CIAAW) of the International Union of Pure and Applied Chemistry (IUPAC) replaced single-value standard atomic weight values with atomic weight intervals for 12 elements (hydrogen, lithium, boron, carbon, nitrogen, oxygen, magnesium, silicon, sulfur, chlorine, bromine, and thallium); for example, the standard atomic weight of nitrogen became the interval [14.00643, 14.00728]. CIAAW recognized that some users of atomic weight data only need representative values for these 12 elements, such as for trade and commerce. For this purpose, CIAAW provided conventional atomic weight values, such as 14.007 for nitrogen, and these values can serve in education when a single representative value is needed, such as for molecular weight calculations. Because atomic weight values abridged to four figures are preferred by many educational users and are no longer provided by CIAAW as of 2015, we provide a table containing both standard atomic weight values and conventional atomic weight values abridged to four figures for the chemical elements. A retrospective review of changes in four-digit atomic weights since 1961 indicates that changes in these values are due to more accurate measurements over time or to the recognition of the impact of natural isotopic fractionation in normal terrestrial materials upon atomic weight values of many elements. Use of the unit “u” (unified atomic mass unit on the carbon mass scale) with atomic weight is incorrect because the quantity atomic weight is dimensionless, and the unit “amu” (atomic mass unit on the oxygen scale) is an obsolete term: Both should be avoided.

German Atomic Energy Act turns fifty

International Nuclear Information System (INIS)

Schneider, Horst

2009-01-01

The German Atomic Energy Act entered into force on January 1, 1960. It turns fifty at the beginning of 2010. Is this a reason to celebrate or rather the opposite? Lawyers, in principle, can view old pieces of legislation from 2 perspectives: On the one hand, aged laws are treated in a spirit of veneration and are celebrated as proven. On the other hand, an anniversary of this kind can be a welcome reason for demands to abolish or, at least, fundamentally renew that law. Over the past half century, the German Atomic Energy Act went through stormy and varied phases both of a legal and a political character. Its 50 th anniversary is likely to spark off very conflicting evaluations as well. A review of legal history shows that the German or, rather, the Federal German Atomic Energy Act (AtG) was not a first-of-its-kind piece of legislation but stemmed from the 1957 EURATOM Treaty, in a way representing a latecomer of that treaty. The Atomic Energy Act experienced a number of important developments throughout its history: - In 1975, compulsory licensing of fuel element factories was introduced. - The back end of the fuel cycle, especially final storage, were incorporated in the Atomic Energy Act comprehensively first in 1976. - In 1985, legislators decided in favor of unlimited nuclear liability. - In 1994 and 1998, only some innovations in special items were introduced under the headings of environmental impact assessment and suitability for repository storage because the controversy about nuclear power did not permit a fundamental alignment towards a more comprehensive modern safety law. - The decision to opt out of the peaceful uses of nuclear power in 2002 drew the final line so far of decisions about directions of nuclear law in a major amendment. In parallel, the decisions by the Federal Constitutional Court and the Federal Administrative Court in the late 1970s and, above all, the 1980s provided important assistance which has remained valid to this day. What is

Revisiting the inelastic electron tunneling spectroscopy of single hydrogen atom adsorbed on the Cu(100) surface

International Nuclear Information System (INIS)

Jiang, Zhuoling; Wang, Hao; Sanvito, Stefano; Hou, Shimin

2015-01-01

Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green’s function formalism combined with density functional theory. The electron-vibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4p z atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices

Instrument response during overpower transients at TREAT

International Nuclear Information System (INIS)

Meek, C.C.; Bauer, T.H.; Hill, D.J.; Froehle, P.H.; Klickman, A.E.; Tylka, J.P.; Doerner, R.C.; Wright, A.E.

1982-01-01

A program to empirically analyze data residuals or noise to determine instrument response that occurs during in-pile transient tests is out-lined. As an example, thermocouple response in the Mark III loop during a severe overpower transient in TREAT is studied both in frequency space and in real-time. Time intervals studied included both constant power and burst portions of the power transient. Thermocouple time constants were computed. Benefits and limitations of the method are discussed

Three-dimensional atom localization via electromagnetically induced transparency in a three-level atomic system.

Science.gov (United States)

Wang, Zhiping; Cao, Dewei; Yu, Benli

2016-05-01

We present a new scheme for three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom in 3D space can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications in laser cooling or atom nano-lithography via atom localization.

Direct imaging of atomic-scale ripples in few-layer graphene.

Science.gov (United States)

Wang, Wei L; Bhandari, Sagar; Yi, Wei; Bell, David C; Westervelt, Robert; Kaxiras, Efthimios

2012-05-09

Graphene has been touted as the prototypical two-dimensional solid of extraordinary stability and strength. However, its very existence relies on out-of-plane ripples as predicted by theory and confirmed by experiments. Evidence of the intrinsic ripples has been reported in the form of broadened diffraction spots in reciprocal space, in which all spatial information is lost. Here we show direct real-space images of the ripples in a few-layer graphene (FLG) membrane resolved at the atomic scale using monochromated aberration-corrected transmission electron microscopy (TEM). The thickness of FLG amplifies the weak local effects of the ripples, resulting in spatially varying TEM contrast that is unique up to inversion symmetry. We compare the characteristic TEM contrast with simulated images based on accurate first-principles calculations of the scattering potential. Our results characterize the ripples in real space and suggest that such features are likely common in ultrathin materials, even in the nanometer-thickness range.

Electrochemical preconcentration and hydride generation methods for trace determination of selenium by atomic absorption spectrometry

International Nuclear Information System (INIS)

Bye, R.

1986-01-01

The use of atomic absorption spectrometry in combination with two different preconcentration/separation techniques for the determination of trace concentrations of selenium is described. Electrochemical preconcentration onto a platinum electrode with a subsequent atomization of selenium is discussed briefly. Several parameters are considered such as the presence of depolarizers, and the temperature of the electrolyzed solutions. Special attention is payed to the efficiency of the atomization step, and a method to improve this is proposed. Applications of the technique to real samples are also reported. Secondly, the separation of the selenium as the volatile selenium hydride from the sample solution is considered. Several papers in this thesis deal with commonly occurring interferants as nickel and copper and with ways of minimizing or avoiding the interferring effects, whereas other papers relate to more theoretical aspects of the hydride generation process. New methods for the determination of selenium in technical samples with high contents of nickel and copper are also presented

Science serving people. International Atomic Energy Agency technical co-operation for development

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-07-01

This brochure tells the story of how the IAEA is helping to harness knowledge to promote development and deliver real benefits to the poor. It demonstrates how nuclear science and technology applications are being employed to overcome the challenges of water scarcity, food insecurity, malnutrition, malaria, environmental degradation and many other problems. It also shows how the complementary development, safety, and security initiatives of the IAEA are fulfilling the 'Atoms for Peace' mandate of the Agency in the developing world.

Science serving people. International Atomic Energy Agency technical co-operation for development

International Nuclear Information System (INIS)

2002-07-01

This brochure tells the story of how the IAEA is helping to harness knowledge to promote development and deliver real benefits to the poor. It demonstrates how nuclear science and technology applications are being employed to overcome the challenges of water scarcity, food insecurity, malnutrition, malaria, environmental degradation and many other problems. It also shows how the complementary development, safety, and security initiatives of the IAEA are fulfilling the 'Atoms for Peace' mandate of the Agency in the developing world

Science serving people. International Atomic Energy Agency technical co-operation for development

International Nuclear Information System (INIS)

2002-12-01

This brochure tells the story of how the IAEA is helping to harness knowledge to promote development and deliver real benefits to the poor. It demonstrates how nuclear science and technology applications are being employed to overcome the challenges of water scarcity, food insecurity, malnutrition, malaria, environmental degradation and many other problems. It also shows how the complementary development, safety, and security initiatives of the IAEA are fulfilling the 'Atoms for Peace' mandate of the Agency in the developing world

Real-time photorealistic stereoscopic rendering of fire

Science.gov (United States)

Rose, Benjamin M.; McAllister, David F.

2007-02-01

We propose a method for real-time photorealistic stereo rendering of the natural phenomenon of fire. Applications include the use of virtual reality in fire fighting, military training, and entertainment. Rendering fire in real-time presents a challenge because of the transparency and non-static fluid-like behavior of fire. It is well known that, in general, methods that are effective for monoscopic rendering are not necessarily easily extended to stereo rendering because monoscopic methods often do not provide the depth information necessary to produce the parallax required for binocular disparity in stereoscopic rendering. We investigate the existing techniques used for monoscopic rendering of fire and discuss their suitability for extension to real-time stereo rendering. Methods include the use of precomputed textures, dynamic generation of textures, and rendering models resulting from the approximation of solutions of fluid dynamics equations through the use of ray-tracing algorithms. We have found that in order to attain real-time frame rates, our method based on billboarding is effective. Slicing is used to simulate depth. Texture mapping or 2D images are mapped onto polygons and alpha blending is used to treat transparency. We can use video recordings or prerendered high-quality images of fire as textures to attain photorealistic stereo.

Atomic hydrogen reactor

International Nuclear Information System (INIS)

Massip de Turville, C.M.D.

1982-01-01

Methods are discussed of generating heat in an atomic hydrogen reactor which involve; the production of atomic hydrogen by an electrical discharge, the capture of nascent neutrons from atomic hydrogen in a number of surrounding steel alloy tubes having a high manganese content to produce 56 Mn, the irradiation of atomic hydrogen by the high energy antineutrinos from the beta decay of 56 Mn to yield nascent neutrons, and the removal of the heat generated by the capture of nascent neutrons by 55 Mn and the beta decay of 56 Mn. (U.K.)

Short-Term Wave Forecasting for Real-Time Control of Wave Energy Converters

OpenAIRE

Fusco, Francesco; Ringwood, John

2010-01-01

Real-time control of wave energy converters requires knowledge of future incident wave elevation in order to approach optimal efficiency of wave energy extraction. We present an approach where the wave elevation is treated as a time series and it is predicted only from its past history. A comparison of a range of forecasting methodologies on real wave observations from two different locations shows how the relatively simple linear autoregressive model, which implicitly models the cyclical beh...

Investigation of phosphorus atomization using high-resolution continuum source electrothermal atomic absorption spectrometry

International Nuclear Information System (INIS)

Dessuy, Morgana B.; Vale, Maria Goreti R.; Lepri, Fabio G.; Welz, Bernhard; Heitmann, Uwe

2007-01-01

The atomization of phosphorus in electrothermal atomic absorption spectrometry has been investigated using a high-resolution continuum source atomic absorption spectrometer and atomization from a graphite platform as well as from a tantalum boat inserted in a graphite tube. A two-step atomization mechanism is proposed for phosphorus, where the first step is a thermal dissociation, resulting in a fast atomization signal early in the atomization stage, and the second step is a slow release of phosphorus atoms from the graphite tube surface following the adsorption of molecular phosphorus at active sites of the graphite surface. Depending on experimental conditions only one of the mechanisms or both might be active. In the absence of a modifier and with atomization from a graphite or tantalum platform the second mechanism appears to be dominant, whereas in the presence of sodium fluoride as a modifier both mechanisms are observed. Intercalation of phosphorus into the graphite platform in the condensed phase has also been observed; this phosphorus, however, appears to be permanently trapped in the structure of the graphite and does not contribute to the absorption signal

Atomic force microscopy. A new method for atom identification and manipulation

International Nuclear Information System (INIS)

Abe, Masayuki; Sugimoto, Yoshiaki; Morita, Seizo

2007-01-01

Frequency modulation atomic force microscopy (FM-AFM) is a scanning probe technique that detects the interaction forces between the outermost atom of a sharp tip and the atoms at a surface to image the sample surface. It is expected that the FM-AFM can cover the research field which scanning tunneling microscopy does not provide. In this article, we would introduce FM-AFM experiments applied to site-specific force measurements and atom manipulation, including how to solve the problems to achieve precise FM-AFM measurements. (author)

Multivariate performance reliability prediction in real-time

International Nuclear Information System (INIS)

Lu, S.; Lu, H.; Kolarik, W.J.

2001-01-01

This paper presents a technique for predicting system performance reliability in real-time considering multiple failure modes. The technique includes on-line multivariate monitoring and forecasting of selected performance measures and conditional performance reliability estimates. The performance measures across time are treated as a multivariate time series. A state-space approach is used to model the multivariate time series. Recursive forecasting is performed by adopting Kalman filtering. The predicted mean vectors and covariance matrix of performance measures are used for the assessment of system survival/reliability with respect to the conditional performance reliability. The technique and modeling protocol discussed in this paper provide a means to forecast and evaluate the performance of an individual system in a dynamic environment in real-time. The paper also presents an example to demonstrate the technique

Real Language Meets Real Business

Science.gov (United States)

Muirhead, Muirhead; Schechter, Sarah

2016-01-01

The Real Business Language Challenge was a collaborative pilot project between Coca-Cola Enterprises (CCE) and Routes into Languages East for Year 9 and 10 pupils. It was based on CCE's award-winning Real Business Challenge, part of its highly acclaimed education programme. The Real Business Language Challenge transformed the project into a…

Computer simulation of electronic excitation in atomic collision cascades

Energy Technology Data Exchange (ETDEWEB)

Duvenbeck, A.

2007-04-05

The impact of an keV atomic particle onto a solid surface initiates a complex sequence of collisions among target atoms in a near-surface region. The temporal and spatial evolution of this atomic collision cascade leads to the emission of particles from the surface - a process usually called sputtering. In modern surface analysis the so called SIMS technology uses the flux of sputtered particles as a source of information on the microscopical stoichiometric structure in the proximity of the bombarded surface spots. By laterally varying the bombarding spot on the surface, the entire target can be scanned and chemically analyzed. However, the particle detection, which bases upon deflection in electric fields, is limited to those species that leave the surface in an ionized state. Due to the fact that the ionized fraction of the total flux of sputtered atoms often only amounts to a few percent or even less, the detection is often hampered by rather low signals. Moreover, it is well known, that the ionization probability of emitted particles does not only depend on the elementary species, but also on the local environment from which a particle leaves the surface. Therefore, the measured signals for different sputtered species do not necessarily represent the stoichiometric composition of the sample. In the literature, this phenomenon is known as the Matrix Effect in SIMS. In order to circumvent this principal shortcoming of SIMS, the present thesis develops an alternative computer simulation concept, which treats the electronic energy losses of all moving atoms as excitation sources feeding energy into the electronic sub-system of the solid. The particle kinetics determining the excitation sources are delivered by classical molecular dynamics. The excitation energy calculations are combined with a diffusive transport model to describe the spread of excitation energy from the initial point of generation. Calculation results yield a space- and time-resolved excitation

Computer simulation of electronic excitation in atomic collision cascades

International Nuclear Information System (INIS)

Duvenbeck, A.

2007-01-01

The impact of an keV atomic particle onto a solid surface initiates a complex sequence of collisions among target atoms in a near-surface region. The temporal and spatial evolution of this atomic collision cascade leads to the emission of particles from the surface - a process usually called sputtering. In modern surface analysis the so called SIMS technology uses the flux of sputtered particles as a source of information on the microscopical stoichiometric structure in the proximity of the bombarded surface spots. By laterally varying the bombarding spot on the surface, the entire target can be scanned and chemically analyzed. However, the particle detection, which bases upon deflection in electric fields, is limited to those species that leave the surface in an ionized state. Due to the fact that the ionized fraction of the total flux of sputtered atoms often only amounts to a few percent or even less, the detection is often hampered by rather low signals. Moreover, it is well known, that the ionization probability of emitted particles does not only depend on the elementary species, but also on the local environment from which a particle leaves the surface. Therefore, the measured signals for different sputtered species do not necessarily represent the stoichiometric composition of the sample. In the literature, this phenomenon is known as the Matrix Effect in SIMS. In order to circumvent this principal shortcoming of SIMS, the present thesis develops an alternative computer simulation concept, which treats the electronic energy losses of all moving atoms as excitation sources feeding energy into the electronic sub-system of the solid. The particle kinetics determining the excitation sources are delivered by classical molecular dynamics. The excitation energy calculations are combined with a diffusive transport model to describe the spread of excitation energy from the initial point of generation. Calculation results yield a space- and time-resolved excitation

Electron spectroscopy of collisional excited atoms

International Nuclear Information System (INIS)

Straten, P. van der.

1987-01-01

In this thesis measurements are described in which coincidences are detected between scattered projectiles and emitted electrons. This yields information on two-electron excitation processes. In order to show what can be learnt from coincidence experiments a detailed theoretical analysis is given. The transition amplitudes, which contain all the information, are introduced (ch.2). In ch.3 the experimental set-up is shown. The results for the Li + -He system are shown in ch. 7 and are compared with predictions based on the Molecular-Orbitalmodel which however does not account for two-excitation mechanisms. With the transition amplitudes also the wave function of the excited atom has been completely determined. In ch.8 the shape of the electron cloud, induced by the collision, is derived from the amplitudes. The relation between the oscillatory motion of this cloud after the collision and the correlation between the two electrons of the excited atom is discussed. In ch. 6 it is shown that the broad structures in the non-coincident energy spectra of the Li + -He system are erroneously interpretated as a result of electron emission from the (Li-He) + -quasimolecule. A model is presented which explains, based on the results obtained from the coincidence measurements, these broad structures. In ch. 4 the Post-Collision Interaction process is treated. It is shown that for high-energy collisions, in contrast with general assumptions, PCI is important. In ch. 5 the importance of PCI-processes in photoionization of atoms, followed by Auger decay, are studied. From the formulas derived in ch. 4 simple analytical results are obtained. These are applied to recent experiments and good agreement is achieved. 140 refs.; 55 figs.; 9 tabs

CO tip functionalization in subatomic resolution atomic force microscopy

International Nuclear Information System (INIS)

Kim, Minjung; Chelikowsky, James R.

2015-01-01

Noncontact atomic force microscopy (nc-AFM) employing a CO-functionalized tip displays dramatically enhanced resolution wherein covalent bonds of polycyclic aromatic hydrocarbon can be imaged. Employing real-space pseudopotential first-principles calculations, we examine the role of CO in functionalizing the nc-AFM tip. Our calculations allow us to simulate full AFM images and ascertain the enhancement mechanism of the CO molecule. We consider two approaches: one with an explicit inclusion of the CO molecule and one without. By comparing our simulations to existing experimental images, we ascribe the enhanced resolution of the CO functionalized tip to the special orbital characteristics of the CO molecule

Design considerations regarding an atomizer for multi-element electrothermal atomic absorption spectrometry

Energy Technology Data Exchange (ETDEWEB)

Katskov, Dmitri A., E-mail: katskovda@tut.ac.za [Department of Chemistry, Tshwane University of Technology, Private Bag X680, Pretoria 0001 (South Africa); Sadagov, Yuri M. [All-Russian Scientific Research Institute of Optical and Physical Measurements (VNIIOFI), Ozernaya St. 46, Moscow 119361 (Russian Federation)

2011-06-15

The methodology of simultaneous multi-element electrothermal atomic absorption spectrometry (ETAAS-Electrothermal Atomic Absorption Spectrometry) stipulates rigid requirements to the design and operation of the atomizer. It must provide high degree of atomization for the group of analytes, invariant respective to the vaporization kinetics and heating ramp residence time of atoms in the absorption volume and absence of memory effects from major sample components. For the low resolution spectrometer with a continuum radiation source the reduced compared to traditional ETAAS (Electrothermal Atomic Absorption Spectrometry) sensitivity should be, at least partially, compensated by creating high density of atomic vapor in the absorption pulse. The sought-for characteristics were obtained for the 18 mm in length and 2.5 mm in internal diameter longitudinally heated graphite tube atomizer furnished with 2-4.5 mg of ring shaped carbon fiber yarn collector. The collector located next to the sampling port provides large substrate area that helps to keep the sample and its residue in the central part of the tube after drying. The collector also provides a 'platform' effect that delays the vaporization and stipulates vapor release into absorption volume having already stabilized gas temperature. Due to the shape of external surface of the tube, presence of collector and rapid (about 10 {sup o}C/ms) heating, an inverse temperature distribution along the tube is attained at the beginnings of the atomization and cleaning steps. The effect is employed for cleaning of the atomizer using the set of short maximum power heating pulses. Preparation, optimal maintenance of the atomizer and its compliance to the multi-element determination requirements are evaluated and discussed. The experimental setup provides direct simultaneous determination of large group of element within 3-4 order concentration range. Limits of detection are close to those for sequential single element

Ionization of highly excited atoms by atomic particle impact

International Nuclear Information System (INIS)

Smirnov, B.M.

1976-01-01

The ionization of a highly excited atom by a collision with an atom or molecule is considered. The theory of these processes is presented and compared with experimental data. Cross sections and ionization potential are discussed. 23 refs

Two-dimensional atom localization via probe absorption in a four-level atomic system

International Nuclear Information System (INIS)

Wang Zhi-Ping; Ge Qiang; Ruan Yu-Hua; Yu Ben-Li

2013-01-01

We have investigated the two-dimensional (2D) atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization

Calibration of atomic trajectories in a large-area dual-atom-interferometer gyroscope

Science.gov (United States)

Yao, Zhan-Wei; Lu, Si-Bin; Li, Run-Bing; Luo, Jun; Wang, Jin; Zhan, Ming-Sheng

2018-01-01

We propose and demonstrate a method for calibrating atomic trajectories in a large-area dual-atom-interferometer gyroscope. The atom trajectories are monitored by modulating and delaying the Raman transition, and they are precisely calibrated by controlling the laser orientation and the bias magnetic field. To improve the immunity to the gravity effect and the common phase noise, the symmetry and the overlap of two large-area atomic interference loops are optimized by calibrating the atomic trajectories and by aligning the Raman-laser orientations. The dual-atom-interferometer gyroscope is applied in the measurement of the Earth's rotation. The sensitivity is 1.2 ×10-6 rad s -1 Hz-1/2, and the long-term stability is 6.2 ×10-8 rad/s at 2000 s.

A study of atomic interaction between suspended nanoparticles and sodium atoms in liquid sodium

International Nuclear Information System (INIS)

Saito, Jun-ichi; Ara, Kuniaki

2010-01-01

A feasibility study of suppression of the chemical reactivity of sodium itself using an atomic interaction between nanoparticles and sodium atoms has been carried out. We expected that the atomic interaction strengthens when the nanoparticle metal is the transition element which has a major difference in electronegativity from sodium. We also calculated the atomic interaction between nanoparticle and sodium atoms. It became clear that the atomic bond between the nanoparticle atom and the sodium atom is larger than that between sodium atoms, and the charge transfer takes place to the nanoparticle atom from the sodium atom. Using sodium with suspended nanoparticles, the fundamental physical properties related to the atomic interaction were investigated to verify the atomic bond. The surface tension of sodium with suspended nanoparticles increased, and the evaporation rate of sodium with suspended nanoparticles also decreased compared with that of sodium. Therefore the presence of the atomic interaction between nanoparticles and sodium was verified from these experiments. Because the fundamental physical property changes by the atomic interaction, we expected changes in the chemical reactivity characteristics. The chemical reaction properties of sodium with suspended nanoparticles with water were investigated experimentally. The released reaction heat and the reaction rate of sodium with suspended nanoparticles were reduced than those of sodium. The influence of the charge state of nanoparticle on the chemical process with water was theoretically investigated to speculate on the cause of reaction suppression. The potential energy in both primary and side reactions changed by the charge transfer, and the free energy of activation of the reaction with water increased. Accordingly, the reaction barrier also increased. This suggests there is a possibility of the reduction in the reaction of sodium by the suspension of nanoparticles. Consequently the possibility of the

Influence of the atomic structure on the quantum state of sputtered Ir atoms

International Nuclear Information System (INIS)

Bastiaansen, J.; Philipsen, V.; Lievens, P.; Silverans, R.E.; Vandeweert, E.

2004-01-01

The probability of the ejection of a neutral atom in a specific quantum state after keV-ion beam sputtering is often interpreted in terms of the interaction between the atomic states of the escaping atom and the electronic states of the solid. In this work, we examined this interplay in the sputtering of iridium as this element has--unlike the elements employed in previous investigations--a complex atomic structure due to strong configuration interactions. Double-resonant two-photon laser ionization is used to probe the sputtered Ir atoms yielding information about the probability for an ejected atom to populate a specific atomic state and its escape velocity. The qualitative features of the corresponding population partition and state-selective velocity distributions show the influence of the excitation energy and the electronic structure of the different atomic states. A comparison is made between the experimental data and predictions from the resonant electron transfer description

AtomPy: A Cloud Atomic-data Service for Astrophysical Applications

Science.gov (United States)

Mendoza, Claudio; Boswell, J. S.; Bautista, M.

2013-06-01

Apart from our long-term commitment to the computing of accurate atomic data for astrophysical applications, we have also been interested in the problems of data access and dissemination. In this respect, one of us took part in the developments of TIPTOPbase [1, 2, 3], the astrophysical opacity server referred to as OPserver [4, 5], and, more recently, of the Virtual Atomic and Molecular Data Center [6, 7]. Our present effort is now with the establishment of a cloud atomic data web service, AtomPy, implemented by means of SOAP web services, Google Drive spreadsheets and Python modules. In the present poster we will describe the outline of this ambitious project, illustrated with some prototypes that are already operational.

Atom and Bond Fukui Functions and Matrices: A Hirshfeld-I Atoms-in-Molecule Approach.

Science.gov (United States)

Oña, Ofelia B; De Clercq, Olivier; Alcoba, Diego R; Torre, Alicia; Lain, Luis; Van Neck, Dimitri; Bultinck, Patrick

2016-09-19

The Fukui function is often used in its atom-condensed form by isolating it from the molecular Fukui function using a chosen weight function for the atom in the molecule. Recently, Fukui functions and matrices for both atoms and bonds separately were introduced for semiempirical and ab initio levels of theory using Hückel and Mulliken atoms-in-molecule models. In this work, a double partitioning method of the Fukui matrix is proposed within the Hirshfeld-I atoms-in-molecule framework. Diagonalizing the resulting atomic and bond matrices gives eigenvalues and eigenvectors (Fukui orbitals) describing the reactivity of atoms and bonds. The Fukui function is the diagonal element of the Fukui matrix and may be resolved in atom and bond contributions. The extra information contained in the atom and bond resolution of the Fukui matrices and functions is highlighted. The effect of the choice of weight function arising from the Hirshfeld-I approach to obtain atom- and bond-condensed Fukui functions is studied. A comparison of the results with those generated by using the Mulliken atoms-in-molecule approach shows low correlation between the two partitioning schemes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Virtual reality cerebral aneurysm clipping simulation with real-time haptic feedback.

Science.gov (United States)

Alaraj, Ali; Luciano, Cristian J; Bailey, Daniel P; Elsenousi, Abdussalam; Roitberg, Ben Z; Bernardo, Antonio; Banerjee, P Pat; Charbel, Fady T

2015-03-01

With the decrease in the number of cerebral aneurysms treated surgically and the increase of complexity of those treated surgically, there is a need for simulation-based tools to teach future neurosurgeons the operative techniques of aneurysm clipping. To develop and evaluate the usefulness of a new haptic-based virtual reality simulator in the training of neurosurgical residents. A real-time sensory haptic feedback virtual reality aneurysm clipping simulator was developed using the ImmersiveTouch platform. A prototype middle cerebral artery aneurysm simulation was created from a computed tomographic angiogram. Aneurysm and vessel volume deformation and haptic feedback are provided in a 3-dimensional immersive virtual reality environment. Intraoperative aneurysm rupture was also simulated. Seventeen neurosurgery residents from 3 residency programs tested the simulator and provided feedback on its usefulness and resemblance to real aneurysm clipping surgery. Residents thought that the simulation would be useful in preparing for real-life surgery. About two-thirds of the residents thought that the 3-dimensional immersive anatomic details provided a close resemblance to real operative anatomy and accurate guidance for deciding surgical approaches. They thought the simulation was useful for preoperative surgical rehearsal and neurosurgical training. A third of the residents thought that the technology in its current form provided realistic haptic feedback for aneurysm surgery. Neurosurgical residents thought that the novel immersive VR simulator is helpful in their training, especially because they do not get a chance to perform aneurysm clippings until late in their residency programs.

Max Auwaerter symposium: spin mapping and spin manipulation on the atomic scale

International Nuclear Information System (INIS)

Wiesendanger, R.

2008-01-01

Full text: A fundamental understanding of magnetic and spin-dependent phenomena requires the determination of spin structures and spin excitations down to the atomic scale. The direct visualization of atomic-scale spin structures has first been accomplished for magnetic metals by combining the atomic resolution capability of Scanning Tunnelling Microscopy (STM) with spin sensitivity, based on vacuum tunnelling of spin-polarized electrons. The resulting technique, Spin-Polarized Scanning Tunnelling Microscopy (SP-STM), nowadays provides unprecedented insight into collinear and non-collinear spin structures at surfaces of magnetic nanostructures and has already led to the discovery of new types of magnetic order at the nanoscale. More recently, the development of subkelvin SP-STM has allowed studies of ground-state magnetic properties of individual magnetic adatoms on non-magnetic substrates as well as the magnetic interactions between them. Based on SP-STM experiments performed at temperatures of 300 mK, indirect magnetic exchange interactions at the sub-milli-electronvolt energy scale between individual paramagnetic adatoms as well as between adatoms and nearby magnetic nanostructures could directly be revealed in real space up to distances of several nanometers. In both cases we have observed an oscillatory behavior of the magnetic exchange coupling, alternating between ferromagnetic and antiferromagnetic, as a function of distance. Moreover, the detection of spin-dependent exchange and correlation forces has allowed a first direct real-space observation of spin structures at surfaces of antiferromagnetic insulators. This new type of scanning probe microscopy, called Magnetic Exchange Force Microscopy (MExFM), offers a powerful new tool to investigate different types of spin-spin interactions based on direct-, super-, or RKKY-type exchange down to the atomic level. By combining MExFM with high-precision measurements of damping forces, localized or confined spin

Real-World Data on Prognostic Factors for Overall Survival in EGFR Mutation-Positive Advanced Non-Small Cell Lung Cancer Patients Treated with First-Line Gefitinib.

Science.gov (United States)

Yao, Zong-Han; Liao, Wei-Yu; Ho, Chao-Chi; Chen, Kuan-Yu; Shih, Jin-Yuan; Chen, Jin-Shing; Lin, Zhong-Zhe; Lin, Chia-Chi; Chih-Hsin Yang, James; Yu, Chong-Jen

2017-09-01

This study aimed to identify independent prognostic factors for overall survival (OS) of patients with advanced non-small cell lung cancer (NSCLC) harboring an activating epidermal growth factor receptor (EGFR) mutation and receiving gefitinib as first-line treatment in real-world practice. We enrolled 226 patients from June 2011 to May 2013. During this period, gefitinib was the only EGFR-tyrosine kinase inhibitor reimbursed by the Bureau of National Health Insurance of Taiwan. The median progression-free survival and median OS were 11.9 months (95% confidence interval [CI]: 9.7-14.2) and 26.9 months (21.2-32.5), respectively. The Cox proportional hazards regression model revealed that postoperative recurrence, performance status (Eastern Cooperative Oncology Grade [ECOG] ≥2), smoking index (≥20 pack-years), liver metastasis at initial diagnosis, and chronic hepatitis C virus (HCV) infection were independent prognostic factors for OS (hazard ratio [95% CI] 0.3 [0.11-0.83], p  = .02; 2.69 [1.60-4.51], p  lung cancer (NSCLC) patients treated with first-line gefitinib may raise awareness of benefit from anti-HCV treatment in this patient population. Brain metastasis in the initial diagnosis or intracranial progression during gefitinib treatment is not a prognostic factor for OS. This study, which enrolled a real-world population of NSCLC patients, including sicker patients who were not eligible for a clinical trial, may have impact on guiding usual clinical practice. © AlphaMed Press 2017.

Signal Processing in Cold Atom Interferometry-Based INS

Science.gov (United States)

2014-03-27

angular rotation. Additionally, because of their particle nature, the atoms may be treated as inertial masses and their movement is used to determine the...G(τ)δβ(τ) = Φ(∆t)xi + wdi where β(t) is a Brownian motion process with dispersion Q, andΦ is the discrete-time state transition matrix [14]. That is...identity matrix, I. βA and βG are 3 × 1 vectors of independent, unity Brownian motions, that is, βA(t) ∼ N (0, t · I) and βG(t) ∼ N (0, t · I). The rate

Hydrogen atom as a quantum-classical hybrid system

International Nuclear Information System (INIS)

Zhan, Fei; Wu, Biao

2013-01-01

Hydrogen atom is studied as a quantum-classical hybrid system, where the proton is treated as a classical object while the electron is regarded as a quantum object. We use a well known mean-field approach to describe this hybrid hydrogen atom; the resulting dynamics for the electron and the proton is compared to their full quantum dynamics. The electron dynamics in the hybrid description is found to be only marginally different from its full quantum counterpart. The situation is very different for the proton: in the hybrid description, the proton behaves like a free particle; in the fully quantum description, the wave packet center of the proton orbits around the center of mass. Furthermore, we find that the failure to describe the proton dynamics properly can be regarded as a manifestation of the fact that there is no conservation of momentum in the mean-field hybrid approach. We expect that such a failure is a common feature for all existing approaches for quantum-classical hybrid systems of Born-Oppenheimer type.

Symmetric Atom–Atom and Ion–Atom Processes in Stellar Atmospheres

Directory of Open Access Journals (Sweden)

Vladimir A. Srećković

2017-12-01

Full Text Available We present the results of the influence of two groups of collisional processes (atom–atom and ion–atom on the optical and kinetic properties of weakly ionized stellar atmospheres layers. The first type includes radiative processes of the photodissociation/association and radiative charge exchange, the second one the chemi-ionisation/recombination processes with participation of only hydrogen and helium atoms and ions. The quantitative estimation of the rate coefficients of the mentioned processes were made. The effect of the radiative processes is estimated by comparing their intensities with those of the known concurrent processes in application to the solar photosphere and to the photospheres of DB white dwarfs. The investigated chemi-ionisation/recombination processes are considered from the viewpoint of their influence on the populations of the excited states of the hydrogen atom (the Sun and an M-type red dwarf and helium atom (DB white dwarfs. The effect of these processes on the populations of the excited states of the hydrogen atom has been studied using the general stellar atmosphere code, which generates the model. The presented results demonstrate the undoubted influence of the considered radiative and chemi- ionisation/recombination processes on the optical properties and on the kinetics of the weakly ionized layers in stellar atmospheres.

Real-world use, safety, and survival of ipilimumab in metastatic cutaneous melanoma in The Netherlands.

Science.gov (United States)

Jochems, Anouk; Leeneman, Brenda; Franken, Margreet G; Schouwenburg, Maartje G; Aarts, Maureen J B; van Akkooi, Alexander C J; van den Berkmortel, Franchette W P J; van den Eertwegh, Alfonsus J M; Groenewegen, Gerard; de Groot, Jan Willem B; Haanen, John B A G; Hospers, Geke A P; Kapiteijn, Ellen; Koornstra, Rutger H; Kruit, Wim H J; Louwman, Marieke W J; Piersma, Djura; van Rijn, Rozemarijn S; Ten Tije, Albert J; Vreugdenhil, Gerard; Wouters, Michel W J M; Uyl-de Groot, Carin A; van der Hoeven, Koos J M

2018-07-01

Phase III trials with ipilimumab showed an improved survival in patients with metastatic melanoma. We evaluated the use and safety of ipilimumab, and the survival of all patients with metastatic cutaneous melanoma (N=807) receiving ipilimumab in real-world clinical practice in The Netherlands using data from the Dutch Melanoma Treatment Registry. Patients who were registered between July 2012 and July 2015 were included and analyzed according to their treatment status: treatment-naive (N=344) versus previously-treated (N=463). Overall, 70% of treatment-naive patients and 62% of previously-treated patients received all four planned doses of ipilimumab. Grade 3 and 4 immune-related adverse events occurred in 29% of treatment-naive patients and 21% of previously-treated patients. No treatment-related deaths occurred. Median time to first event was 5.4 months [95% confidence interval (CI): 4.7-6.5 months] in treatment-naive patients and 4.4 months (95% CI: 4.0-4.7 months) in previously-treated patients. Median overall survival was 14.3 months (95% CI: 11.6-16.7 months) in treatment-naive patients and 8.7 months (95% CI: 7.6-9.6 months) in previously-treated patients. In both patient groups, an elevated lactate dehydrogenase level (hazard ratio: 2.25 and 1.70 in treatment-naive and previously-treated patients, respectively) and American Joint Committee on Cancer M1c-stage disease (hazard ratio: 1.81 and 1.83, respectively) were negatively associated with overall survival. These real-world outcomes of ipilimumab slightly differed from outcomes in phase III trials. Although phase III trials are crucial for establishing efficacy, real-world data are of great added value enhancing the generalizability of outcomes of ipilimumab in clinical practice.

Atomic physics

CERN Document Server

Born, Max

1969-01-01

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.

The Effect of Vibration Characteristics on the Atomization Rate in a Micro-Tapered Aperture Atomizer

Directory of Open Access Journals (Sweden)

Qiufeng Yan

2018-03-01

Full Text Available Because little is known about the atomization theory of a micro-tapered aperture atomizer, we investigated the vibration characteristics of this type of atomizer. The atomization mechanism of a micro-tapered aperture atomizer was described, and the atomization rate equation was deduced. As observed via microscopy, the angle of the micro-tapered aperture changes with the applied voltage, which proved the existence of a dynamic cone angle. The forward and reverse atomization rates were measured at various voltages, and the influence of the micro-tapered aperture and its variation on the atomization rate was characterized. The resonance frequency of the piezoelectric vibrator was obtained using a laser vibrometer, and the atomization rates were measured at each resonance frequency. From experiments, we found that the atomization rates at the first five resonance frequencies increased as the working frequency increased. At the fifth resonance frequency (121.1 kHz, the atomization rate was maximized (0.561 mL/min, and at the sixth resonance frequency (148.3 kHz, the atomization rate decreased significantly (0.198 mL/min. The experimental results show that the vibration characteristics of the piezoelectric vibrator have a relatively strong impact on the atomization rate. This research is expected to contribute to the manufacture of micro-tapered aperture atomizers.