Norwegian Open Research Archives (NORA)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The solvation properties of a chlorine ion in small water clusters are investigated using state-of-the-art statistical mechanics. The simulations employ the polarizable water model developed recently by Dang [J. Chem. Phys. [bold 97], 2659 (1992)]. The ion--water interaction potentials are defined such that the successive binding energies for the ionic clusters, and the solvation enthalpy, bulk vertical binding energy, and structural properties of the aqueous solution agree with the best available results obtained from experiments. Simulated vertical electron binding energies of the ionic clusters Cl[sup [minus

International Nuclear Information System (INIS)

Ion desorption from a condensed gas solid Ne impacted by singly- and multiply-charged Ar"q"+ ions (q = 1-7) has been investigated. Various secondary ions such as cluster ions, Ne"+_n (n = 2-20) as well as atomic ions are observed. Mass spectral patterns, thickness dependence of the yields, and kinetic energy distributions of the desorbed Ne"+_n (n = 1,2) depend strongly on the projectile charge state. These results indicate that the dissipation of the projectile potential energy on the surface leads to the desorption of the monomer and small cluster ions by a Coulomb repulsion between adjacent target ions.

Energy Technology Data Exchange (ETDEWEB)

Motivated by the discovery of superconductivity in alkali and alkaline earth fullerides, this program was undertaken both to understand the nature of and expand the range of materials demonstrating superconductivity. The first approach involved attempts to modify the fullerene cage by incorporating heteroatoms in the structure and the preparation and photophysical properties of nitrogen and sulfur doped fullerenes were studied in detail. The second approach involved examining the stoichiometry and effect of preparative conditions on the behavior of alkali, alkaline earth, lanthanide and mixed ion fullerides. In particular, the authors have elaborated on a technique for making such salts using liquid ammonia or aliphatic amines as solvents. Thirdly, modeling studies were undertaken to predict the properties of heterohedral fullerines and metal - C60 complexes, and theoretical guidelines were developed for understanding the ...

Energy Technology Data Exchange (ETDEWEB)

A detailed investigation of the damage formation and evolution in ion-implanted crystalline Si is presented. Deep-level transient spectroscopy has been used to monitor room temperature migration of point defect complexes and evolution from simple point-like defect complexes to defect clusters and even extended defects. Si samples were implanted with Si or He ions with energies of 145 keV-3MeV, to fluences in the range 5x10[sup 8]-5x10[sup 13]cm[sup -2]. The effects of thermal annealing, in the range 100-680 C and 10 min-15h, were also explored. A systematic comparison of defect complexes formation and evolution in ion-implanted or electron-irradiated Si samples with a different impurity content were used to assess the role of impurities (C and O), extra implanted ion and defect clustering on the nature and thermal stability of residual damage. In particular, an ...

International Nuclear Information System (INIS)

The model of transient enhanced diffusion of ion-implanted As is formulated and the finite-difference method for numerical solution of the system of equations obtained is developed. The nonuniform distribution of point defects near the interface and more accurate description of arsenic clustering are simultaneously taken into account. Simulation of As diffusion during rapid annealing gives a reasonable agreement with the experimental data. (authors)

British Library Electronic Table of Contents (United Kingdom)

We present structure calculations of neutral and singly ionized Mg clusters of up to 30 atoms, as well as Na clusters of up to 10 atoms. The calculations have been performed using density functional theory (DFT) within the local (spin-)density approximation, ion cores are described by pseudopotentials. We have utilized a new algorithm for solving the Kohn-Sham equations that is formulated entirely in coordinate space and, thus, permits straightforward control of the spatial resolution. Our numerical method is particularly suitable for modern parallel computer architectures; we have thus been able to combine an unrestricted simulated annealing procedure with electronic structure calculations of high spatial resolution, corresponding to a plane-wave cutoff of 954 eV for Mg. We report the geo...

International Nuclear Information System (INIS)

Liquid metal ion sources (LMISs) with Ga as ion species are widely used in focused ion beam (FIB) technology for micromachining and surface treatment on the sub-micron and nano-scale. Key features of a LMIS for investigating mechanical properties and 3D-microfabrication of materials are long life-time, high brightness, stable ion current and a highly effective milling ability for the material to be modified. In order to increase the material removal rate, heavier ions than Ga and their clusters should be applied. Bismuth (Bi) is the heaviest, non-radio-active element in the periodic table, is non-toxic and exhibits a low melting point. We have thus produced a long-life (about 1000 h) Bi LMIS with a good beam performance, applicable in any FIB system. Since Bi is the only element in this source, it is not necessary to separate it from other ...

Energy Technology Data Exchange (ETDEWEB)

The ALICE heavy-ion particle physics experiment is currently being built at CERN near Geneva. It will use a PC cluster of 900 dual-processor machines for the last stages of the data readout process and a network of 400 microcomputers for the configuration and control of the cluster nodes. One of the most important objectives to be achieved in such experiments is to guarantee the utilized devices are running correctly during the experiment life-time. A second aspect is the extremely high availability and reliability requirements of the applications being run, the so called high level trigger (HLT). The SysMES framework is a scalable, decentralized, fault tolerant, dynamic, rule based tool set for the monitoring of networks of target systems and applications. The management algorithms consist of the following steps: system and application monitoring, recognition of undesirable states, event (message) generation, local event ...

Energy Technology Data Exchange (ETDEWEB)

The performance of a high temperature ion source coupled to a helium gas-jet transport system for an efficient mass separation of neutron-rich alkaline earth and lanthanide isotopes is reported and the results of overall efficiency measurements using different cluster materials in the gas-jet are given. A fast, microprocessor controlled tape transport system for ..gamma..-spectroscopic studies on short-lived isotopes is described. Some results on the decay of 3.8sub(-s) /sup 152/Pr are presented.

International Nuclear Information System (INIS)

For the purpose of optimizing the process of co-implantation of MeV Si ions to reduce boron transient enhanced diffusion and boron-enhanced diffusion in Si, multiple MeV implantations and annealing at different temperatures have been performed. A slight improvement on the suppression of B diffusion is observed by adding a low temperature annealing step after the MeV implantation. No differences in B diffusion are observed when the Si doses are increased from 1 x 10"1"5 to 1 x 10"1"6 cm"-"2. This dose independent behavior is speculated to be a quasi-steady state of vacancy cluster evaporation.

International Nuclear Information System (INIS)

We present results from a kinetic Monte Carlo simulation of boron transient enhanced diffusion (TED) in silicon. Our approach avoids the use of phenomenological fits to experimental data by using a complete and self-consistent set of values for defect and dopant energetics derived mostly from ab initio calculations. The results predict that, during annealing of 40 keV B-implanted Si at 800 degree C, there exists a time window during which all the implanted boron atoms are substitutional. At earlier or later times, the interactions between free silicon self-interstitials and boron atoms drive the growth of boron clusters and result in an inactive boron fraction. The results show that the majority of boron TED takes place during the growth period of interstitial clusters and not during their dissolution. copyright 1998 American Institute of Physics.

Energy Technology Data Exchange (ETDEWEB)

A unified physically based ion implantation damage model has been developed which successfully predicts both the impurity profiles and the damage profiles for a wide range of implant conditions for arsenic, phosphorus, BF{sub 2}, and boron implants into single-crystal silicon. In addition, the amorphous layer thicknesses predicted by this new damage model are also in excellent agreement with experimental measurements. This damage model is based on the physics of point defects in silicon, and explicitly simulates the defect production, diffusion, and their interactions which include interstitial-vacancy recombination, clustering of same type of defects, defect-impurity complex formation, emission of mobile defects from clusters, and surface effects for the first time. New computationally efficient algorithms have been developed to overcome the barrier of the excessive computational requirements. In addition, the new model ...

International Nuclear Information System (INIS)

Becchetti's reply to the preceding ''Comment on "4H clustering in lithium nuclei''.

CERN Document Server

We present structure calculations of neutral and singly ionized Mg clusters of up to 30 atoms, as well as Na clusters of up to 10 atoms. The calculations have been performed using density functional theory (DFT) within the local (spin-)density approximation, ion cores are described by pseudopotentials. We have utilized a new algorithm for solving the Kohn-Sham equations that is formulated entirely in coordinate space and, thus, permits straightforward control of the spatial resolution. Our numerical method is particularly suitable for modern parallel computer architectures; we have thus been able to combine an unrestricted simulated annealing procedure with electronic structure calculations of high spatial resolution, corresponding to a plane-wave cutoff of 954eV for Mg. We report the geometric structures of the resulting ground-state configurations and a few low-lying isomers. The energetics and HOMO-LUMO gaps of the ...

CERN Document Server

Problem statement: Clustering has a number of techniques that have been developed in statistics, pattern recognition, data mining, and other fields. Subspace clustering enumerates clusters of objects in all subspaces of a dataset. It tends to produce many over lapping clusters. Approach: Subspace clustering and projected clustering are research areas for clustering in high dimensional spaces. In this research we experiment three clustering oriented algorithms, PROCLUS, P3C and STATPC. Results: In general, PROCLUS performs better in terms of time of calculation and produced the least number of un-clustered data while STATPC outperforms PROCLUS and P3C in the accuracy of both cluster points and relevant attributes found. Conclusions/Recommendations: In this study, we analyze in ...

International Nuclear Information System (INIS)

In this paper, we report kinetic Monte Carlo study on the diffusion behavior of boron in silicon crystal, more particularly on the transient enhanced diffusion (TED) of boron in silicon during implantation and annealing. Firstly, the accuracy of our KMC code was verified by investigating the time evolutionary behavior of interstitial (I) and vacancy (V) when a silicon substrate is implanted with silicon dose with an energy of 10 keV and with a dose of 1 X 10"1"4 ions/cm"2. To investigate the influence of native defects (I, V) on boron diffusion, a single and multi boron markers grown by MBE were employed. The simulation results revealed that the precursor of boron cluster (BI_2) is dominant at the initial stage of annealing, which explains the boron TED phenomenon in terms of the concentration of boron complexes and I, V clusters, respectively. The formation of #left brace#311#right brace# defects and dislocation loop were ...

International Nuclear Information System (INIS)

A new atomistic approach to Si device process simulation is presented. It is based on a Monte Carlo diffusion code coupled to a binary collision program. Besides diffusion, the simulation includes recombination of vacancies and interstitials, clustering and re-emission from the clusters, and trapping of interstitials. We discuss the simulation of a typical room-temperature implant at 40 keV, 5x10"1"3 cm"-"2 Si into (001)Si, followed by a high temperature (815 degree C) anneal. The damage evolves into an excess of interstitials in the form of extended defects and with a total number close to the implanted dose. This result explains the success of the open-quote open-quote+1 close-quote close-quote model, used to simulate transient diffusion of dopants after ion implantation. It is also in agreement with recent transmission electron microscopy observations of the number of interstitials stored in (311) defects. copyright 1996 ...

International Nuclear Information System (INIS)

In this work the diffusion of ion-beam-injected self-interstitials (Is) and their interaction with impurities in crystalline Si are presented. In particular, the I penetration into a molecular beam epitaxy grown Si structure was studied by means of diffusion effects induced on B spikes, analyzed by a developed simulation code. Trapping effects at sample-surface and bulk are evidenced and modeled. The B marker approach was extended to the two-dimensional (2D) I-diffusion occurring as a consequence of ion implantation through a sub-micron dimension patterned oxide mask. I-source size effects on the I penetration have been found and modeled, quantitatively describing the 2D I-diffusion. The I-substitutional carbon interactions have been also studied, showing the C ability to effectively retain Is. The I-trapping mechanism was quantitatively studied by the simulation code, showing that one I is able to deactivate about two C traps by means of ...

International Nuclear Information System (INIS)

A study has been made of B transient enhanced diffusion (TED) in heavily P-doped Si using secondary ion mass spectroscopy (SIMS) and positron annihilation spectroscopy (PAS). The P-doped silicon was implanted with boron ions of 40 keV energy to a dose of 3 x 10"1"4 cm"-"2, and then annealed at temperatures ranging from 700--1,000 C in a N_2 ambient for varying durations. As P doping concentration increased from 3 x 10"1"9 to 1 x 10"2"0 cm"-"3, boron diffusivity and the immobile boron fraction decreased. The experimental results are inconsistent with the predictions of the Fermi-level model and suggest that the clustering between B atoms and Si interstitials should be invoked in order to explain the immobile portion of the B peak during TED.

International Nuclear Information System (INIS)

Decaborane (B_1_0H_1_4) cluster ions were implanted into n-Si(100) substrates to fabricate shallow p"+/n junctions. Implant energies of 2 keV, 5 keV, and 20 keV, equivalent to implant energies of the monomer boron ion of 174 eV, 435 eV, and 1.74 keV, respectively, were used at dosages of 1 X 10"1"2 /cm"2 and 1 X 10"1"3 /cm"2. The implanted samples were then subjected to activation annealing at 800 .deg. C, 900 .deg. C, and 1000 .deg. C for 10 s. By using secondary ion mass spectrometry (SIMS) depth profiles, we determined that the depth of the shallow junction (D_s) at a dosage of 1 X 10"1"3 /cm"2 was in the range 12 nm - 45 nm after annealing at 1000 .deg. C. D_s and transient enhanced diffusion (TED) were greatly reduced at implant energies lower than 5 keV, but thermal diffusion (TD) smoothly decreased. In particular, TED was suppressed in the p"+/n junction implanted at 2 keV and a dosage of 1 X ...

KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during initial annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, the authors have used B doping marker layers in Si to probe the injection of interstitials from near-surface, non-amorphizing Si implants during annealing. The in-diffusion of interstitials is limited by trapping at impurities and has an activation energy of {approximately}3.5 eV. Substitutional C is the dominant trapping center with a binding energy of 2--2.5 eV. The high interstitial supersaturation adjacent to the implant damage drives substitutional B into metastable clusters at concentrations below the B solid solubility limit. Transmission electron microscopy shows that the interstitials driving TED are emitted from {l_brace}311{r_brace} defect clusters in the damage region at a rate which also exhibits an activation energy of 3.6 ...

International Nuclear Information System (INIS)

The polycrystalline samples of Y_2_-_xHo_xO_3 (0.10#<=#x#<=#1.80) were synthesized by ceramic technology. The X-ray powder diffraction data were collected and the crystal structures were refined by the Rietveld method for the samples Y_2_-_xHo_xO_3 (x=0.00, 0.20, 0.40, 1.20, 1.80, 2.00). Holmium ions Ho"3"+ were randomly distributed over two cationic sites 8b and 24d in the space group Ia3 in all refined structures. Cation-anion-cation bonds important for superexchange interaction were determined. Magnetic susceptibility measurements were done by the Faraday method in the temperature range 290 to 620 K and a behaviour in accordance with the Curie-Weiss law was obtained. The molar Curie's constants linearly depend on concentration. The effective magnetic moments of Ho"3"+ ions were smaller than the free ion value. The Curie-Weiss paramagnetic temperatures indicated antiferromagnetic interaction. The gram ...

International Nuclear Information System (INIS)

For an assessment of the future US spallation neutron source (SNS) target performance, radiation induced hardening and microstructural evolution were investigated as a function of ion dose for EC316LN stainless steel. Irradiation was carried out using 3.5 MeV Fe"+, 360 keV He"+, and 180 keV H"+ simultaneous ion-beams at 200 deg. C to simulate the damage, He and H production in the SNS target vessel wall. At low dose (< 1 dpa), the predominant defects were black dots whose number density saturated rapidly within a few dpa. This was followed by the evolution of interstitial loops whose number density saturated below 15 dpa. Although He-bubbles were not visible, severely scalloped loops suggested that the implanted He/H atoms existed in the form of small clusters. Comparison with reported neutron irradiation data showed that hardening and ductility loss occurred mostly in the black dot regime (< 1 dpa), but that good ...

International Nuclear Information System (INIS)

Ultra-shallow junction formation in deep submicron Si devices is limited by anomalous diffusion of the dopant, which is related to the release of interstitials from defect clusters formed during the implantation of energetic ions or the subsequent annealing. The work described in this dissertation is concerned with the effects of low energy B ion implantation, especially damage formation, clustering and its annealing. After a review of the stopping and ranges of energetic ions in Si, the formation of implant damage, in particular of point defects, their migration, agglomeration and annihilation, including the involvement of dopant ions, is considered. A description of the Salford ultra low energy implanter is given and the main analysis technique, medium ion energy scattering (MEIS) reviewed. Additional analytical techniques used, such as ...

CERN Document Server

Globular clusters are found usually in galaxies and they are an excellent tracer of dark matter. Long ago it was suggested that there may exist intracluster globular clusters (IGCs) bound to a galaxy cluster rather than to any single galaxy. Here we present a map showing the large scale distribution of globular clusters over the entire Virgo cluster. It shows that IGCs are found out to 5 million light years from the Virgo center, and that they are concentrated in several substructures much larger than galaxies. These objects might have been mostly stripped off from low-mass dwarf galaxies.

International Nuclear Information System (INIS)

Reactions of reducing species from acetonitrile media with silver iodide particles (#approx#25-angstrom diameter) have been investigated by pulse radiolysis techniques. Injection of electrons into these ultrasmall particles leads to transient bleaching of the adsorption of AgI at wavelengths close to the onset of absorption (#approx#400 nm) with the concomitant reduction of AgI to metallic silver. The reduction of Ag"+ ions and formation of silver atoms and/or dimeric Ag_2 molecules on three different size AgI particles (#approx#100, 35, and #approx#25 angstrom) have also been examined by picosecond laser spectroscopy.

International Nuclear Information System (INIS)

Accurate modeling of the enhanced diffusion of boron during rapid thermal annealing has been accomplished by incorporating the effects of extended defect formation and annealing on enhanced diffusion into a multizone, semiempirical model. The multizone model divides the implant profile into three zones defining regions of different defects and diffusion enhancements. The model also contains the initial enhanced diffusion and the transient diffusion effects associated with the dissolution of defect clusters and the annealing of extended defects, respectively. The saturation time for transient-enhanced diffusion contains an exponential function of implant dose in order to model the increase in point defect generated with higher implant dose. As a result, the model accurately simulates the boron diffusion profile over a wide range of implant doses and also shows the immobile boron peak of precipitated dopants produced during high dose implantation.

Energy Technology Data Exchange (ETDEWEB)

A new principle of particle trapping in the simple spherical cavity using both electric and magnetic components of radiofrequency electromagnetic field is proposed. The electric component of H {sub 12} oscillating mode drives the fast particle oscillations, while the magnetic component synchronously bends the trajectories to the cavity center. A specially developed theory of particle stability predicts dense and energetic electron cluster in the trap. Numerical simulations of particle dynamics in the complete electromagnetic field taking into account both space charge and particle-induced magnetic field are in good agreement with the analytic results, giving a density of 2.6*10{sup 1} electrons/cm{sup 3} and an average kinetic energy of around 30 keV at an operating frequency of 3 GHz. Being used at lower frequency, spherical cavity can trap protons and heavier ions too, but with lower density and kinetic energy.

Energy Technology Data Exchange (ETDEWEB)

Results are presented of molecular dynamics (MD) studies of 1-10 keV displacement cascades in silicon. At these energies, the simulations couple directly to experimental observations of low energy implantation in silicon for shallow junction formation. The simulations are performed with the Stillinger-Weber potential for silicon in computational cells with up to 3.5x10{sup 5} atoms. The author employs periodic boundary conditions in the [100] and [010] directions and a free surface on the top (001) plane. The author discusses the results in terms of the structural evolution and the dynamics of the cascade zones. For sufficiently high energy recoils (>2 KeV), the cascades produce locally molten zones that result in the formation of amorphous silicon pockets upon recrystallization. Frenkel pairs are also produced during the cascade, although their number is very small (less than 10% of the binary collision predictions). Upon annealing of the resulting damage microstructure at 1100K ...

Environmental Research Database

Objectives1. We will use reduction of lysosomal stability as an indicator of cell injury induced by C-60 fullerenes and carbon nanotubes in the liver analogue or digestive gland (hepatopancreas) of marine mussels. Molluscan hepatopancreatic digestive cells are key to normal function and are a sensitive key interface with the environment. Reduction of lysosomal stability is mechanistically linked with impaired health of the whole animal. 2. We will also test the hepatopancreatic digestive cells for evide [continued...]DescriptionNanotechnology is a major innovative scientific and economic growth area, which may present a variety of hazards for environmental and human health. The surface properties and very small size of nanoparticles and nanotubes provides surfaces that may bind and transport toxic chemical pollutants, as well as possibly being toxic in their own right by generating reactive oxygen species (ROS). There is a wealth of evidence ...

International Nuclear Information System (INIS)

Ion implantation of Si (60 keV, 1x10"1"4/cm"2) has been used to introduce excess interstitials into silicon predoped with high background concentrations of B, which were varied between 1x10"1"8 and 1x10"1"9/cm"3. Following post-implantation annealing at 740 degree C for 15 min to allow agglomeration of the available interstitials into elongated #left brace#311#right brace# defects, the density of the agglomerated interstitials was determined by plan-view transmission electron microscopy observation of the defects. We report a significant reduction in the fraction of excess interstitials trapped in #left brace#311#right brace# defects as a function of boron concentration, up to nearly complete disappearance of the #left brace#311#right brace# defects at boron concentrations of 1x10"1"9/cm"3. The reduction of the excess interstitial concentration is interpreted in terms of boron-interstitial clustering, and implications for transient-enhanced ...

Energy Technology Data Exchange (ETDEWEB)

A study has been made of B transient enhanced diffusion (TED) in heavily P-doped Si using secondary ion mass spectroscopy (SIMS) and positron annihilation spectroscopy (PAS). The P-doped silicon was implanted with boron ions of 40 keV energy to a dose of 3 {times} 10{sup 14} cm{sup {minus}2}, and then annealed at temperatures ranging from 700--1,000 C in a N{sub 2} ambient for varying durations. As P doping concentration increased from 3 {times} 10{sup 19} to 1 {times} 10{sup 20} cm{sup {minus}3}, boron diffusivity and the immobile boron fraction decreased. The experimental results are inconsistent with the predictions of the Fermi-level model and suggest that the clustering between B atoms and Si interstitials should be invoked in order to explain the immobile portion of the B peak during TED.

UK PubMed Central (United Kingdom)

BackgroundThe search for cluster structure in microarray datasets is a base problem for the so-called "-omic sciences". A difficult problem in clustering is how to handle data with...Full Text Available

British Library Electronic Table of Contents (United Kingdom)

The individuality of production devices should be taken into account when statistical models are designed for parallelized devices. In the present work, a new clustering method, referred to as NC-spectral clustering, is proposed for discriminating the individuality of production devices. The key idea is to classify samples according to the differences of the correlation among measured variables, since the individuality of production devices is expressed by the correlation. In the proposed NC-spectral clustering, the nearest correlation (NC) method and spectral clustering are integrated. The NC method generates the weighted graph that expresses the correlation-based similarities between samples, and the constructed graph is partitioned by spectral clustering. A new statistical process monit...

Science.gov (United States)

This paper describes the anelastic strain recovery and the strain hardening of amorphous metals and presents the experimental result that creep deformation is represented by a viscoelastic model consisting of rheological elements. Materials studied were 80Pd--20Si, 80Fe--13P--7C, and 60 Cu--40 Zr. (DLC)

Energy Technology Data Exchange (ETDEWEB)

Implanted B and P dopants in Si exhibit transient enhanced diffusion (TED) during annealing which arises from the excess interstitials generated by the implant. In order to study the mechanisms of TED, transmission electron microscopy measurements of implantation damage were combined with B diffusion experiments using doping marker structures grown by molecular-beam epitaxy (MBE). Damage from nonamorphizing Si implants at doses ranging from 5{times}10{sup 12} to 1{times}10{sup 14}/cm{sup 2} evolves into a distribution of {l_brace}311{r_brace} interstitial agglomerates during the initial annealing stages at 670{endash}815{degree}C. The excess interstitial concentration contained in these defects roughly equals the implanted ion dose, an observation that is corroborated by atomistic Monte Carlo simulations of implantation and annealing processes. The injection of interstitials from the damage region involves the dissolution of {l_brace}311{r_brace} defects during ...

CERN Document Server

This paper describes the approach taken to the XML Mining track at INEX 2008 by a group at the Queensland University of Technology. We introduce the K-tree clustering algorithm in an Information Retrieval context by adapting it for document clustering. Many large scale problems exist in document clustering. K-tree scales well with large inputs due to its low complexity. It offers promising results both in terms of efficiency and quality. Document classification was completed using Support Vector Machines.

CERN Document Server

Mining Time Series data has a tremendous growth of interest in today's world. To provide an indication various implementations are studied and summarized to identify the different problems in existing applications. Clustering time series is a trouble that has applications in an extensive assortment of fields and has recently attracted a large amount of research. Time series data are frequently large and may contain outliers. In addition, time series are a special type of data set where elements have a temporal ordering. Therefore clustering of such data stream is an important issue in the data mining process. Numerous techniques and clustering algorithms have been proposed earlier to assist clustering of time series data streams. The clustering algorithms and its effectiveness on various applications are compared to develop a new method to solve the existing problem. This paper ...

CERN Document Server

We present maps of the cosmic large-scale structure around the twelve most distant galaxy clusters from the Massive Cluster Survey (MACS) as traced by the projected surface density of galaxies on the cluster red sequence. Taken with the Suprime-Cam wide-field camera on the Subaru telescope, the images used in this study cover a 27x27 arcmin^2 area around each cluster, corresponding to 10 x 10 Mpc^2 at the median redshift of z = 0.55 of our sample. We directly detect satellite clusters and filaments extending over the full size of our imaging data in the majority of the clusters studied, supporting the picture of mass accretion via infall along filaments suggested by numerical simulations of the growth of clusters and the evolution of large-scale structure. A comparison of the galaxy distribution near the cluster cores ...

Energy Technology Data Exchange (ETDEWEB)

We present ab-initio calculations of the electronic structure of small Fe clusters (1-9 atoms) on Ni(001), Ni(111), Cu(001) and Cu(111) surfaces. Our focus is on the spin moments and their dependence on cluster size and shape. We derive a simple quantitative rule that relates the moment of each Fe atom linearly to its coordination number. Thus, for an arbitrary Fe cluster the spin moment of the cluster and of the individual Fe atoms can be readily found if the positions of the atoms are known. (orig.)

Energy Technology Data Exchange (ETDEWEB)

The research supported by this Department of Energy contract has primarily been devoted to the study of the electronic properties of surfaces with sub-micron size. In previous years, we have studied the photoexcitation of electrons from field emission tips by a focussed Argon-ion laser beam tuned to operate at specific photon energy. The photoexcited electrons escape into the vacuum by tunneling through a surface potential barrier which is distorted by the application of a strong electric field. The interest in these experiments lies in a better understanding of the photoexcitation process at low photon energies. The techniques that have been developed directly measure the excited state energy distribution of electrons emitted through the surface potential barrier. The basic information gained from this research is relevant to opto-electronic devices which rely on photoexcitation of electrons in the presence of strong interfacial electric fields for their ...

Energy Technology Data Exchange (ETDEWEB)

We present an atomistic simulation of the Ostwald ripening of extrinsic defects (clusters, {l_brace}1 1 3{r_brace}s and dislocation loops) which occurs during annealing of ion implanted silicon. The model describes the capture and emission of Si interstitial atoms to and from extrinsic defects of sizes up to thousands of atoms and includes a loss term due to the flux of interstitials to the recombining surface. Key input parameters of the simulation are the variations of the formation energy and of the capture efficiency with the size of the different defects. This model shows that the kinetics of the well-known dissolution of {l_brace}1 1 3{r_brace} defects is only driven by the recombination efficiency at the surface and the distance from the defects to the sample surface. We have subsequently used this model to study defect evolution in low and ultra low energy (ULE) B implanted Si during annealing. Defect dissolution occurs earlier and at ...

Energy Technology Data Exchange (ETDEWEB)

We have simulated the transient enhanced diffusion (TED) of boron fluoride (BF{sub 2}{sup +}) implanted in crystalline and germanium amorphized silicon. Based on recently published models, the effect of fluorine on boron diffusion in silicon has been introduced and a modelling has been suggested. In order to simulate the boron experimental profiles, we have assumed that fluorine forms clusters involving interstitial boron which reduces the junction depth. Experimental results indicate that fluorine behaviour depends on amorphization energy. Moreover, even no germanium preamorphization is performed, silicon is still amorphized by fluorine species. Hence, BF{sub 2}{sup +} implantation leads to an amorphous/crystalline (a/c) interface near the surface. An improvement of published models is suggested taking into account fluorine effects. The simulations satisfactory reproduce the SIMS experimental profiles for a large scale of experimental conditions.

Energy Technology Data Exchange (ETDEWEB)

The research supported by this Department of Energy contract has primarily been devoted to the study of the electronic properties of surfaces with sub-micron size. In previous years, we have studied the photoexcitation of electrons from field emission tips by a focussed Argon-ion laser beam tuned to operate at specific photon energy. The photoexcited electrons escape into the vacuum by tunneling through a surface potential barrier which is distorted by the application of a strong electric field. The interest in these experiments lies in a better understanding of the photoexcitation process at low photon energies. The techniques that have been developed directly measure the excited state energy distribution of electrons emitted through the surface potential barrier. The basic information gained from this research is relevant to opto-electronic devices which rely on photoexcitation of electrons in the presence of strong interfacial electric fields for their ...

International Nuclear Information System (INIS)

The spatial distribution of argon clusters in gas jet is tested using the Rayleigh scattering method. A pulsed laser is used to acquire the whole evolution of the cluster inside one event. The measured results at a fixed axial position show that the argon clusters grow in less than one millisecond after the nozzle is opened and the cluster size keeps constant during the whole open period of 20 ms. Further results show that the scattering signal along the radial direction is almost Gaussian-distributed and the full width half maximum (FWHM) increases almost linearly when the distance from nozzle increases. The scattering signal along the axial direction is Landau-distributed and the area near the nozzle is most effective for laser cluster interaction. (authors)

CERN Document Server

We report electronic and magnetic structure of arsenic-doped manganese clusters from density-functional theory using generalized gradient approximation for the exchange-correlation energy. We find that arsenic stabilizes manganese clusters, though the ferromagnetic coupling between Mn atoms are found only in Mn$_2$As and Mn$_4$As clusters with magnetic moments 9 $\\mu_B$ and 17 $\\mu_B$, respectively. For all other sizes, $x=$ 3, 5-10, Mn$_x$As clusters show ferrimagnetic coupling. It is suggested that, if grown during the low temperature MBE, the giant magnetic moments due to ferromagnetic coupling in Mn$_2$As and Mn$_4$As clusters could play a role on the ferromagnetism and on the variation observed in the Curie temperature of Mn-doped III-V semiconductors.

Science.gov (United States)

The properties and kinetics of x-ray stars in globular clusters are described. Locations, configurations, star evolution, massive close binary systems, various mechanisms, and the x-ray burster properties are included. (JFP)

Energy Technology Data Exchange (ETDEWEB)

The dependence of the rms radius of the deuteron cluster in /sup 6/Li on the relative d-..cap alpha.. momentum was investigated on the basis of the three-body wave function given by Rai, Lehman, and Ghovanlou.

British Library Electronic Table of Contents (United Kingdom)

Metalloid cluster compounds of group 14 of the general formulae EnRm with n > m (E = Si, Ge, Sn, Pb; R = ligand), where naked as well as ligand bound tetrel atoms are present, represent a novel class of cluster compounds in group 14 chemistry and can be seen as intermediates on the way to the elemental state. Therefore, interesting properties are expected for these compounds, which might complement results from nanotechnology. In this article, first results for germanium are discussed, together with novel build-up reactions on the way to novel materials based on metalloid cluster compounds. GRAPHICAL ABSTRACT[image omitted

Science.gov (United States)

PMID:21910487

Energy Technology Data Exchange (ETDEWEB)

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the only major protection to astronauts from harmful exposure. Unlike low-linear energy transfer (LET) {gamma} or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure, since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak. The Bragg curve does not necessarily represent the biological damage along the particle traversal, and the 'biological Bragg curve' is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. Here we used a unique irradiation geometry to measure the biological response across the Bragg curve in human fibroblasts exposed to 577MeV/nucleon incident Fe ions ...

Energy Technology Data Exchange (ETDEWEB)

In this paper we present the design, implementation, and experimental results of a system to mine and visualize event data using cluster computingbuilt upon an ATM network. Our approach is to build a system using light weight, modular software tools for data management, resource management, data analysis and visualization developed for local, campus and wide area clusters of workstations. (author)

International Nuclear Information System (INIS)

We study the dynamical evolution of globular clusters containing primordial binaries, including full single and binary stellar evolution using our Monte Carlo cluster evolution code updated with an adaptation of the single and binary stellar evolution codes SSE and BSE from Hurley et al. We describe the modifications that we have made to the code. We present several test calculations and comparisons with existing studies to illustrate the validity of the code. We show that our code finds very good agreement with direct N-body simulations including primordial binaries and stellar evolution. We find significant differences in the evolution of the global properties of the simulated clusters using stellar evolution compared with simulations without any stellar evolution. In particular, we find that the mass loss from the stellar evolution acts as a significant energy production channel simply by reducing the total gravitational ...

International Nuclear Information System (INIS)

Point defect injection studies are performed to investigate how fluorine implantation influences the diffusion of boron marker layers in both the vacancy-rich and interstitial-rich regions of the fluorine damage profile. A 185 keV, 2.3x10"1"5 cm"-"2 F"+ implant is made into silicon samples containing multiple boron marker layers and rapid thermal annealing is performed at 1000 deg. C for times of 15-120 s. The boron and fluorine profiles are characterized by secondary ion mass spectroscopy and the defect structures by transmission electron microscopy (TEM). Fluorine implanted samples surprisingly show less boron diffusion under interstitial injection than those under inert anneal. This effect is particularly noticeable for boron marker layers located in the interstitial-rich region of the fluorine damage profile and for short anneal times (15 s). TEM images show a band of dislocation loops around the range of the fluorine implant and the density of dislocation ...

British Library Electronic Table of Contents (United Kingdom)

Nest locations of breeding birds are often spatially clustered. This tendency to nest together has generally been related to a patchy distribution of nesting habitat in landscape studies, but behavioral studies of species with clustered breeding patterns draw attention to the importance of social and biotic factors. Indeed, it is becoming increasingly apparent that the breeding system of many territorial, migrant birds may be semi-colonial. The reasons for, and extent of, spatial clustering in their breeding systems are not well understood. Our goal was to tease apart the influence of habitat availability and social drivers of clustered breeding in a neotropical migrant species, the hooded warbler (Wilsonia citrina). To test alternative hypotheses related to clustered habitat or conspecifi...

CERN Document Server

We use direct N-body simulations to investigate the evolution of star clusters with large size-scales with the particular goal of understanding the so-called extended clusters observed in various Local Group galaxies, including M31 and NGC6822. The N-body models incorporate a stellar mass function, stellar evolution and the tidal field of a host galaxy. We find that extended clusters can arise naturally within a weak tidal field provided that the tidal radius is filled at the start of the evolution. Differences in the initial tidal filling-factor can produce marked differences in the subsequent evolution of clusters and the size-scales that would be observed. These differences are more marked than any produced by internal evolution processes linked to the properties of cluster binary stars or the action of an intermediate-mass black hole, based on models performed in this work and ...

International Nuclear Information System (INIS)

The authors describe the application of an approximate fuzzy C-means (AFCM) clustering algorithm as a data dimension reduction approach to medical magnetic resonance images (MRI). Image data consisted of one T1-weighted, two T2-weighted, and one T2*-weighted (magnetic susceptibility) image for each cranial study and a matrix of 10 images generated from 10 combinations of TE and TR for each body lymphoma study. All images were obtained with a 1.5 Tesla imaging system (GE Signa). Analyses were performed on over 100 MR image sets with a variety of pathologies. The cluster analysis was operated in an unsupervised mode and computational overhead was minimized by utilizing a table look-up approach without adversely affecting accuracy. Image data were first segmented into 2 coarse clusters, each of which was then subdivided into 16 fine clusters. The final tissue classifications were presented as color-coded ...

Energy Technology Data Exchange (ETDEWEB)

Methods and apparatus are described for efficient photodetachment and purification of negative ion beams. A method of purifying an ion beam includes: inputting the ion beam into a gas-filled multipole ion guide, the ion beam including a plurality of ions; increasing a laser-ion interaction time by collisional cooling the plurality of ions using the gas-filled multipole ion guide, the plurality of ions including at least one contaminant; and suppressing the at least one contaminant by selectively removing the at least one contaminant from the ion beam by electron photodetaching at least a portion of the at least one contaminant using a laser beam.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

British Library Electronic Table of Contents (United Kingdom)

All-atom molecular dynamics simulations were used to study the morphology of polymer/inorganic composite particles prepared by heterocoagulation. The results were also compared to those of our previous study of the preparation of TiO2/poly(acrylic acid-co-methyl methacrylate) and Fe3O4/polystyrene composite particles. In the simulation system, polymer or inorganic particles were simulated by surface-charge-modified C60 or Na atoms. Through a combination of analysis of the radial distribution functions of charged atoms and snapshots of the equilibrated structure, three kinds of particle distributions were observed under different conditions. When the polymer and inorganic particles had opposite surface charges and their sizes were very different, the composite morphology showed a core-shell...

Science.gov (United States)

The fuel cell control problem was studied. Attempts were made to control the output current of the fuel cell by starving it of hydrogen and oxygen. The motivation of this work was to increase efficiency by minimizing waste of fuel. The following findings were obtained: H2 starvation works better than O2 starvation; An optimal H2 to O2 ratio exists for combined H2&O2 starvation; The control scheme for H2&O2 starvation works well for 3 different disturbance tests and at 25 degrees C, 60 degrees C, and 80 degrees C; Fuel cell under reactant starvation is stable for at least 72 hrs.

CERN Document Server

We present the results of a monitoring campaign aimed at deriving rotation periods for a representative sample of stars in the young (30 Myr) open cluster IC 2602. Rotation periods were derived for 29 of 33 stars monitored. The periods derived range from 0.2d (one of the shortest known rotation periods of any single open cluster star) to about 10d (which is almost twice as long as the longest period previously known for a cluster of this age). We are able to confirm 8 previously known periods and derive 21 new ones, delineating the long period end of the distribution. Despite our sensitivity to longer periods, we do not detect any variables with periods longer than about 10d. The combination of these data with those for IC 2391, an almost identical cluster, leads to the following conclusions: 1) The fast rotators in a 30 Myr cluster are distributed across the entire 0.5 < B-V ...

CERN Document Server

Finding "densely connected clusters" in a graph is in general an important and well studied problem in the literature \\cite{Schaeffer}. It has various applications in pattern recognition, social networking and data mining \\cite{Duda,Mishra}. Recently, Ames and Vavasis have suggested a novel method for finding cliques in a graph by using convex optimization over the adjacency matrix of the graph \\cite{Ames, Ames2}. Also, there has been recent advances in decomposing a given matrix into its "low rank" and "sparse" components \\cite{Candes, Chandra}. In this paper, inspired by these results, we view "densely connected clusters" as imperfect cliques, where imperfections correspond missing edges, which are relatively sparse. We analyze the problem in a probabilistic setting and aim to detect disjointly planted clusters. Our main result basically suggests that, one can find \\emph{dense} clusters in a ...

CERN Document Server

Given a point set S and an unknown metric d on S, we study the problem of efficiently partitioning S into k clusters while querying few distances between the points. In our model we assume that we have access to one versus all queries that given a point s in S return the distances between s and all other points. We show that given a natural assumption about the structure of the instance, we can efficiently find an accurate clustering using only O(k) distance queries. We use our algorithm to cluster proteins by sequence similarity. This setting nicely fits our model because we can use a fast sequence database search program to query a sequence against an entire dataset. We conduct an empirical study that shows that even though we query a small fraction of the distances between the points, we produce clusterings that are close to a desired clustering given by manual classification.

International Nuclear Information System (INIS)

Transient Enhanced Diffusion (TED) of boron in silicon is driven by the large supersaturations of self-interstitial silicon atoms left after implantation which also often lead to the nucleation and subsequent growth, upon annealing, of extended defects. In this paper we review selected experimental results and concepts concerning boron diffusion and/or defect behavior which have recently emerged with the ion implantation community and briefly indicate how they are, or will be, currently used to improve 'predictive simulations' softwares aimed at predicting TED. In a first part, we focus our attention on TED and on the formation of defects in the case of 'direct' implantation of boron in silicon. In a second part, we review our current knowledge of the defects and of the diffusion behavior of boron when annealing preamorphised Si. In a last part, we try to compare these two cases and to find out what are the reasons for some similarities and many differences in ...

International Nuclear Information System (INIS)

The concentration of trace elements in brain sections was measured by synchrotron radiation X-ray fluorescence. The relative concentration was calculated by means of the normalization of Compton scattering intensity approximately 22 keV, after the normalization for collecting time of X-ray spectrum and the counting of the ion chamber, and subtracting the contribution of the polycarbonate film for supporting sample. Furthermore, the statistical evaluation of the element distribution in various regions of the brain sections of the 20-day-old rats was tested. For investigating the distribution of elements in the brain of iodine deficient rats, Wistar rats were fed with iodine deficient diet and deionized water (ID group). The rats were fed the same iodine deficient diet, but drank KIO_3 solution as control (CT group). The results showed that the contents of calcium (Ca) in thalamus (TH) and copper (Cu) and iron (Fe) in cerebral cortex (CX) of ID rats were ...

CERN Document Server

We present radial velocity and photometry for four early-type, massive double-lined spectroscopic binaries in the R136 cluster. Three of these systems are eclipsing, allowing orbital inclinations to be determined. One of these systems, R136-38 (O3 V + O6 V), has one of the highest masses ever measured, 57 Mo, for the primary. Comparison of our masses with those derived from standard evolutionary tracks shows excellent agreement. We also identify five other light variables in the R136 cluster which are worthy of follow-up study.

CERN Document Server

The avalanche quantity of the information developed by mankind has led to concept of automation of knowledge extraction - Data Mining ([1]). This direction is connected with a wide spectrum of problems - from recognition of the fuzzy set to creation of search machines. Important component of Data Mining is processing of the text information. Such problems lean on concept of classification and clustering ([2]). Classification consists in definition of an accessory of some element (text) to one of in advance created classes. Clustering means splitting a set of elements (texts) on clusters which quantity are defined by localization of elements of the given set in vicinities of these some natural centers of these clusters. Realization of a problem of classification initially should lean on the given postulates, basic of which - the aprioristic information on primary set of texts and a measure of affinity of ...

UK PubMed Central (United Kingdom)

BackgroundElementary schools represent both a source of childhood sun exposure and a setting for educational interventions.MethodsSun Protection...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A prediction of delayed neutron yields for actinides which are important in the nuclear energy field is given. The prediction is based on a correlation related to a suggested cluster structure of the nucleus. (author).

Science.gov (United States)

These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster ...

Energy Technology Data Exchange (ETDEWEB)

Globular clusters are quite compact (size {proportional_to}10 pc) objects distributed spherically around the galaxy. They contain about 10{sup 5}-10{sup 6} mostly old stars. The number of millisecond pulsars in typical globular cluster is expected to be large (of the order of 100). We investigate the possible mechanism of production of high energy gamma-rays in those objects. Part of the wind energy of pulsars (energy conversion factor) is converted into relativistic leptons. Those leptons can upscatter in inverse Compton process low energy starlight and CMB photons and produce gamma-rays. MAGIC is an Imaging Atmospheric Cerenkov Telescopes located at Canary island of La Palma. We present results and discussion of the MAGIC observations of globular cluster M13.

Science.gov (United States)

star evolution, globular cluster structure and evolution, massive stars, supernova remnants, reflection nebulae, interstellar dust, structure of the ISM, ...

Science.gov (United States)

These include, but are not limited to: stellar winds and outflows, post-main- sequence stellar evolution, binary/multiple star evolution, globular cluster structure ...

UK PubMed Central (United Kingdom)

In natural ecosystems, hundreds of species typically share the same environment and are connected by a dense network of interactions such as predation or competition for resources. Much is known about...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Background The identification of sequences that control transcription in metazoans is a major goal of genome analysis. In a previous study, we demonstrated that searching for clusters of predicted transcription factor binding sites could discover active regulatory sequences, and identified 37 regions of the Drosophila melanogaster genome with high densities of predicted binding sites for five transcription factors involved in anterior-posterior embryonic patterning. Nine of these clusters overlapped known enhancers. Here, we report the results of in vivo functional analysis of 27 remaining clusters. Results We generated transgenic flies carrying each cluster attached to a basal promoter and reporter gene, and assayed embryos for reporter gene expression. Six clusters are enhancers of adjacent genes: giant, fushi tarazu, odd-skipped, nubbin, squeeze and pdm2; three drive expression ...

CERN Document Server

Inferring cluster structure in microarray datasets is a fundamental task for the -omic sciences. A fundamental question in Statistics, Data Analysis and Classification, is the prediction of the number of clusters in a dataset, usually established via internal validation measures. Despite the wealth of internal measures available in the literature, new ones have been recently proposed, some of them specifically for microarray data. In this dissertation, a study of internal validation measures is given, paying particular attention to the stability based ones. Indeed, this class of measures is particularly prominent and promising in order to have a reliable estimate the number of clusters in a dataset. For those measures, a new general algorithmic paradigm is proposed here that highlights the richness of measures in this class and accounts for the ones already available in the literature. Moreover, some of the most ...

CERN Document Server

Conceptual Design of Superconducting Quadrupole Arrays for the Heavy-Ion Fusion

UK PubMed Central (United Kingdom)

BackgroundThe Prospective Space-Time scan statistic (PST) is widely used for the evaluation of space-time clusters of point event data. Usually a window of cylindrical shape is employed,...Full Text Available

International Nuclear Information System (INIS)

The electronic structure of octahedral metal atom clusters Me_6 of 3d, 4d, and 5d transition metal atoms (V, Cr; Nb, Mo; Ta, W) has been calculated applying two different quantum-chemical approximation methods (Extended Hueckel (EH) method; SW-Xsub(alpha) method). Equilibrium structures, energy level schemes, Fermi energies and band widths as well as densities of states of clusters are discussed in detail.

Science.gov (United States)

Aluminium toxicity is a major problem in agriculture worldwide. Among the cultivated triticeae, rye (Secale cereale L.) is one of the most Al-tolerant and represents an important potential source of Al-tolerance for improvement of wheat. The Alt4 Al-tolerance locus of rye contains a cluster of genes...

Energy Technology Data Exchange (ETDEWEB)

In recent years, the influences of acid rain such as the acidification of lake water, on bio-system by the heavy metals from effluent of soils with acid rain and also on the structural materials of buildings are seriously discussed. Sulfur and nitrogen that are contained in fossil fuels are released into the atmosphere by the fuel combustion as their oxides dissolve in rain drops as sulfite and nitrous ions, where they are further oxidized into sulfate and nitrate ions These ions lower the pH of rain water resulting so-called acid rain. Therefore, it is important to accurately determine these ions in rain water for the investigation of reality of acid rain. However, it is not easy to accurately determine these ions, especially for sulfite ions in rain water, since they are quickly oxidized by the catalytic action of metallic ions such as ...

Energy Technology Data Exchange (ETDEWEB)

There are 13 Electron Beam Ion Sources in operation which produce highly charged ions, up to Th{sup 80+} and Xe{sup 53+}. Most of the sources are used to study these ions under electron impact or when recombining with gaseous or solid targets. That provides an insight into the atomic physics of these highly charged ions and into the physics of the plasma in which such ions can be found. This paper reviews the present knowledge of atomic processes, important in the production of such ions with an EBIS.

International Nuclear Information System (INIS)

Seeing convolved two-dimensional de Vaucouleurs profiles have been fitted to digital images of the brightest elliptical galaxies in two nearby groups of galaxies and three clusters of galaxies with redshifts in the range 0.06 to 0.15. The digital images were created by scanning electronographic plates obtained by the use of several versions of the RGO electronographic camera. The linear relation between effective surface brightness #mu#/sub e/ and the logarithm of the effective radius r/sub e/, first discovered by Kormendy to be valid for nearby elliptical galaxies, is found to be equally valid for the largest and brightest galaxies in rich clusters of galaxies. The apparent universal nature of that relation indicates that the same type of processes might have been involved during the formation of all ellipticals from cD galaxies in clusters to fainter ellipticals in small groups. It is suggested that the (I/sub e/,r/sub ...

Energy Technology Data Exchange (ETDEWEB)

A simulation model for boron diffusion which takes into account the aggregation of the excess interstitials in clusters, and subsequently, the dissolution of these defects, is proposed. The interstitial supersaturation and generation rate are determined according to the classical theory of nucleation and growth of particles, in analogy with the precipitation of a new phase in heavily doped silicon. The clusters are considered as precipitates formed by interstitial Si atoms. The B diffusion is modelled on the basis of the dopant-interstitial pair diffusion mechanism. The clusters dissolution during annealing maintains nearly constant, for a long period, the interstitial supersaturation and the related enhancement of the boron diffusion. This gives a good account of the diffusion results over a large range of experimental conditions. Furthermore, this approach describes most of the behavior of the transient enhanced diffusion ...

International Nuclear Information System (INIS)

The formation of the ions charge and energy distributions of the ions slowed down or randomly changing their charge in the collisions with the medium particles are studied. The effect of the ions dispersion by the charge on the Bragg curve form is investigated. The proposed diffusion approximation for the heavy ions kinetic equation makes it possible to determine simply the parameters of the ions distribution by charge and energy on the whole way of the ions motion. The relation between the ions charge distribution characteristics and the cross sections of the ionization-recombination processes is indicated. The ions distributions, calculated in the proposed analytical model, are compared with the results of the numerical calculations. Good agreement between the analytical, numerical and experimental results is obtained

Energy Technology Data Exchange (ETDEWEB)

Optical frequency comb technology has been used in this work for the first time to investigate the nuclear structure of light radioactive isotopes. Therefore, three laser systems were stabilized with different techniques to accurately known optical frequencies and used in two specialized experiments. Absolute transition frequency measurements of lithium and beryllium isotopes were performed with accuracy on the order of 10{sup -10}. Such a high accuracy is required for the light elements since the nuclear volume effect has only a 10{sup -9} contribution to the total transition frequency. For beryllium, the isotope shift was determined with an accuracy that is sufficient to extract information about the proton distribution inside the nucleus. A Doppler-free two-photon spectroscopy on the stable lithium isotopes {sup 6,7}Li was performed in order to determine the absolute frequency of the 2S {yields} 3S transition. The achieved relative accuracy of 2 x 10{sup -10} is improved by one ...

International Nuclear Information System (INIS)

Published in summary form only.

Energy Technology Data Exchange (ETDEWEB)

The red sequence is an important feature of galaxy clusters and plays a crucial role in optical cluster detection. Measurement of the slope and scatter of the red sequence are affected both by selection of red sequence galaxies and measurement errors. In this paper, we describe a new error corrected Gaussian Mixture Model for red sequence galaxy identification. Using this technique, we can remove the effects of measurement error and extract unbiased information about the intrinsic properties of the red sequence. We use this method to select red sequence galaxies in each of the 13,823 clusters in the maxBCG catalog, and measure the red sequence ridgeline location and scatter of each. These measurements provide precise constraints on the variation of the average red galaxy populations in the observed frame with redshift. We find that the scatter of the red sequence ridgeline increases mildly with redshift, and that the slope ...

International Nuclear Information System (INIS)

The properties of negative-ion beams are very important for designing negative-ion apparatus and applications of negative-ion beams, especially, electron detachment cross-sections at the interaction between negative-ion beams and gas particles in the transport system, and secondary-electron emission factors when negative ions are incident on solid surfaces. These properties of negative-ion beams were investigated experimentally as a function of the ion energy under 50 keV. The single electron detachment cross-sections are almost constant in the other of 10"-"1"5 cm"2 in this energy range, but double electron detachment cross-sections increase in proportion to the ion velocity and much smaller than the single one. As for the secondary-electron emission factor, the emission factors for negative-ion ...

International Nuclear Information System (INIS)

(Sep 1973). United Kingdom Sinanoglu, O. Luken, W. Yale Univ., New Haven,

CERN Document Server

We provide a quantitative assessment of the probability distribution function of the concentration parameter of galaxy clusters. We do so by using the probability distribution function of halo formation times, calculated by means of the excursion set formalism, and a formation redshift-concentration scaling derived from results of N-body simulations. Our results suggest that the observed high concentrations of several clusters are quite unlikely in the standard Lambda CDM cosmological model, but that due to various inherent uncertainties, the statistical range of the predicted distribution may be significantly wider than commonly acknowledged. In addition, the probability distribution function of the Einstein radius of A1689 is evaluated, confirming that the observed value of ~45" +/- 5" is very improbable in the currently favoured cosmological model. If, however, a variance of ~20% in the theoretically predicted value of the virial radius is ...

International Nuclear Information System (INIS)

Recently, molecular clusters are the subject of several experimental and computational studies by means of their bonding structures. We studied, first time, small difluorine monoxide clusters such as dimer (linear, cyclic, bifurcated), trimer and tetramer structures using B3LYP variant of density functional theory with cc-pVDZ basis set. On the basis of the optimized geometry, various energy properties such as binding energy, molecular orbital energies, two and three body interaction energies have been calculated. Additionally dipole moment, polarizability, anisotropic polarizability and hyper polarizability have been calculated and compared with monomer structure.

British Library Electronic Table of Contents (United Kingdom)

This paper addresses the problem of partitioning a local service region into nonoverlapping work areas in which pickups and deliveries are made throughout the day. For a fleet of homogeneous vehicles, a given set of customers, and expected demand for service, the objective is to find the least number of work areas or clusters that satisfy a variety of geometric and capacity constraints. Using rectangles as the basic shape, each cluster must have an aspect ratio that falls within certain bounds, as well as meet load and time requirements dictated by the capacity of a vehicle and the working hours in a day, respectively. The latter requirement presents a unique hurdle because travel times are a function of the actual routes followed by the drivers, and are not known, even in a probabilistic ...

CERN Document Server

Dark matter particles form halos that contribute the major part of the mass of galaxy clusters. The formation of these cosmological structures have been investigated both observationally and in numerical simulations, which have confirmed the existence of a universal mass profile. However, the dynamic behaviour of dark matter in halos is not as well understood. We have used observations of 16 equilibrated galaxy clusters to show that the random velocities of dark matter particles are larger on average along the radial direction than along the tangential, and that the magnitude of this velocity anisotropy is radially varying. Our measurement implies that the collective behaviour of dark matter particles is fundamentally different from that of normal particles and the radial variation of the anisotropy velocity agrees with the predictions of numerical simulation.

CERN Document Server

In this paper we present a model and simulator for many clusters of heterogeneous PCs belonging to a local network. These clusters are assumed to be connected to each other through a global network and each cluster is managed via a local scheduler which is shared by many users. We validate our simulator by comparing the experimental and analytical results of a M/M/4 queuing system. These studies indicate that the simulator is consistent. Next, we do the comparison with a real batch system and we obtain an average error of 10.5\\% for the response time and 12\\% for the makespan. We conclude that the simulator is realistic and well describes the behaviour of a large-scale system. Thus we can study the scheduling of our system called \\dirac in a high throughput context. We justify our decentralized, adaptive and opportunistic approach in comparison to a centralized approach in such a context.

International Nuclear Information System (INIS)

In a sufficiently large cluster of several polar molecules, collective interactions lead to localization or 'solvation' of electrons. The existence of the solvated electron is known since 1863 in liquid ammonia and since 1962 for liquid water. In 1984, electron localization in clusters was experimentally demonstrated in (H_2O)_N_#>=#_1_1 and (NH_3)_N_#>=#_3_4 clusters. In cooperation with K. Bowen, we recently initiated a test of the theory of electron binding by a dipole and a new ground state dipole bound dimer anion, (H_2O..NH_3), was predicted and observed. We here describe results of a search for new dipole-bound and solvated electron systems. (author).

CERN Document Server

We analyse the issues involved in the management and mining of astrophysical data. The traditional approach to data management in the astrophysical field is not able to keep up with the increasing size of the data gathered by modern detectors. An essential role in the astrophysical research will be assumed by automatic tools for information extraction from large datasets, i.e. data mining techniques, such as clustering and classification algorithms. This asks for an approach to data management based on data warehousing, emphasizing the efficiency and simplicity of data access; efficiency is obtained using multidimensional access methods and simplicity is achieved by properly handling metadata. Clustering and classification techniques, on large datasets, pose additional requirements: computational and memory scalability with respect to the data size, interpretability and objectivity of clustering or classification results. ...

International Nuclear Information System (INIS)

Molecular cluster predictions for electronic energy levels, wave functions, momentum densities, and Compton profiles of VO and VO_2 are examined within the Hartree-Fock-Slater model. VO_6 clusters are treated in O/subh/, D_4/subh/, and D_2/subh/ symmetry to obtain quantitative relations between distortion parameters and level shifts and splittings. Effects of the crystal environment are taken into account by a potential field. Results for VO are consistent with the augmented plane-wave band calculation of Mattheiss and x-ray emission data; the VO_2 levels are in good agreement with x-ray photoelectron spectroscopy data. A sizable anisotropy is predicted for the Compton profile of VO and VO_2.

Energy Technology Data Exchange (ETDEWEB)

The relationship between X chromosome-linked adrenoleukodystrophy and the red/green color pigment gene cluster on Xq28 was investigated in a large kindred. The DNA in a hemizygous male showed altered restriction fragment sizes compatible with at least a deletion extending from the 5[prime] end of the color pigment genes. Segregation analysis using a DNA probe within the color pigment gene cluster showed significant linkage with adrenoleukodystrophy (logarithm of odds score of 3.19 at [theta] = 0.0). These data demonstrate linkage, rather than association, between a unique molecular rearrangement in the color pigment gene cluster and adrenoleukodystrophy. The DNA changes in this region are thus likely to be helpful for determining the location and identity of the responsible gene. 33 refs., 4 figs.

Energy Technology Data Exchange (ETDEWEB)

Taking the development of large current, negative ion sources which is in progress aiming at nuclear fusion reactors and the development of high luminance ion sources planned as a part of the Omega Project as the examples, the technology for generating high power ion beams is explained. Both these projects are positioned at the limit of the present technology of high power ion beam application as their targeted beam power reaches several tens MW. Consequently, the requirement for the ion sources is severe, and in particular, the generation of the ion beams having large current density with good convergence is beyond all precedents. The application of high power ion sources has been realized as the neutral beam injectors for large tokamaks. Also the hydrogen negative ion source of large current and the electrostatic ...

Energy Technology Data Exchange (ETDEWEB)

One of the keystones of the canceled BTeV experiment (proposed at Fermilab's Tevatron) was its sophisticated three-level trigger. The trigger was designed to reject 99.9% of light-quark background events and retain a large number of B decays. The BTeV Pixel Detector provided a 3-dimensional, high resolution tracking system to detect B signatures. The Level 1 pixel detector trigger was proposed as a two stage process, a track-segment finder and a vertex finder which analyzed every accelerator crossing. In simulations the track-segment finder stage outputs an average of 200 track-segments per accelerator crossing (2.5MHz). The vertexing stage finds vertices and associates track-segments with the vertices found. This paper proposes a novel adaptive pattern recognition model to find the number and the estimated location of vertices, and to cluster track-segments around those vertices. The track clustering and vertex finding is done in ...

CERN Document Server

The Sunyaev-Zeldovich (SZ) effect gives a measure of the thermal energy and electron pressure in groups and clusters of galaxies. In the near future SZ surveys will map hundreds of systems, shedding light on the pressure distribution in the systems. The thermal energy is related to the total mass of a system of galaxies, but it is only a projection that is observed through the SZ effect. A model for the 3D distribution of pressure is needed to link the SZ signal to the total mass of the system. In this work we construct an empirical model for the 2D and 3D SZ profile, and compare it to a set of realistic high resolution SPH simulations of galaxy clusters and groups, and to a stacked SZ profile for massive clusters derived from WMAP data. Furthermore, we combine observed temperature profiles with dark matter potentials to yield an additional constraint, under the assumption of hydrostatic equilibrium. We find a very tight ...

UK PubMed Central (United Kingdom)

BackgroundIn many of the European countries affected by Bovine Spongiform Encephalopathy (BSE), case clustering patterns have been observed. Most of these patterns have been interpreted...Full Text Available

UK PubMed Central (United Kingdom)

Previous studies have been conducted in gene expression profiling to identify groups of genes that characterize the colorectal carcinoma disease. Despite the success of previous attempts to identify...Full Text Available

UK PubMed Central (United Kingdom)

ObjectiveTo refine the CT prediction of emphysema by comparing histology and CT for specific regions of lung. To incorporate both regional lung density measured by CT and cluster...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The A(..pi../sup +/,/sup 3/He)B reaction near threshold is studied in a model where the pion is absorbed by an /sup 4/He constituent of the target nucleus. The predictions of this model using harmonic oscillator cluster wave functions agree semi-quantitatively with the experimental data on the inverse reaction.

UK PubMed Central (United Kingdom)

Noncoding RNAs play important roles in various aspects of gene regulation. We have identified 7SK RNA to be enriched in nuclear speckles or interchromatin granule clusters (IGCs), a subnuclear domain...Full Text Available

CERN Document Server

We present the results of an isophotal shape analysis of three samples of galaxies in the Coma cluster. Quantitative morphology, together with structural and photometric parameters, is given for each galaxy. Special emphasis has been placed on the detailed classification of early-type galaxies. The three samples are: i) a sample of 97 early-type galaxies brighter than m_B = 17.00 falling within one degree from the center of the Coma cluster; these galaxies were observed with CCD cameras, mostly in good to excellent resolution conditions; ii) a magnitude complete sample of 107 galaxies of all morphological types down to m_B = 17.00 falling in a circular region of 50 arcmin diameter, slightly offcentered to the North-West of the cluster center; the images for this and the next sample come from digitized photographic plates; iii) a complete comparison sample of 26 galaxies of all morphological types down to m_R = 16.05 (or m_B ...

UK PubMed Central (United Kingdom)

In the course of a prenatal diagnosis for beta thalassaemia by linkage analysis of restriction fragment length polymorphisms, a homozygous beta thalassaemia fetus was misdiagnosed as beta thalassaemia...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundMass treatment to trachoma endemic communities is a critical part of the World Health Organization SAFE strategy. However, non-participation may not be at random, affecting...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundMuch of our current understanding of the epidemiology of Ascaris lumbricoides infections in humans has been acquired by analyzing worm count data. These...Full Text Available

UK PubMed Central (United Kingdom)

Bovine embryos can be generated by in vitro fertilization or somatic nuclear transfer; however, these differ from their in vivo counterparts in many aspects and exhibit a higher proportion of developmental...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundEvent-related potentials (ERPs) may be used as a highly sensitive way of detecting subtle degrees of cognitive dysfunction. On the other hand, impairment of cognitive skills...Full Text Available

UK PubMed Central (United Kingdom)

Molecular analysis of the amo gene cluster in Nitrosococcus oceani revealed that it consists of five genes, instead of the three known genes, amoCAB....Full Text Available

UK PubMed Central (United Kingdom)

Radionuclides are distributed nonuniformly in tissue. The present work examined the impact of nonuniformities at the multicellular level on the lethal effects of ²¹⁰Po. A three-dimensional...Full Text Available

UK PubMed Central (United Kingdom)

BackgroundMost analyses of spatial clustering of disease have been based on either residence at the time of diagnosis or current residence. An underlying assumption in these analyses...Full Text Available

Science.gov (United States)

Space Telescope is six years old today! Tomorrow's picture: In the Center of the Whirlpool | Archive | Index | Search | Glossary | Education | About APOD | See Explanation....

UK PubMed Central (United Kingdom)

BackgroundImproving nutrition knowledge among children may help them to make healthier food choices. The aim of this study was to assess the effectiveness and acceptability of a...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

This paper reports progress in the fabrication and characterization of an array of 1nm-scale colloidal particles (i.e., quantum-dot array) that can be operated to execute nontrivial and innovative computations, possibly including quantum logic. We discuss the actual fabrication of 2-nm metal clusters as an example of possible quantum dot implementation. Innovative and unconventional paradigms underlie the different stages of this work. For example, regular array geometry is achieved by directing appropriately derivatized metal clusters to preselected locations along a stretched strand of an engineered DNA sequence.

British Library Electronic Table of Contents (United Kingdom)

There is proposed the nonlinear model of dose dependence saturation of the yield strength on the base of the vacancy and interstitial barrier interaction in this work. Processes of mutual recombination of vacancy and interstitial barriers and formation of vacancy and interstitial clusters are taken into consideration. In the framework of the model, the analytical equations corresponding to the evolution of the barrier densities and yield strength are obtained. It is shown that the yield strength of irradiated materials decreases with the increasing intensity of barrier recombination processes, the dependence being nonlinear. Also it is shown that the model is valid both for low doses and large doses on the stage of radiation hardening.

Energy Technology Data Exchange (ETDEWEB)

Artificial Neural Networks (ANNs) are parallel distributed processing machines. The unique characteristics of ANNs are: Fault tolerance, robustness, plasticity and generalization. These offer great potential in many AI applications such as character recognition. Handwritten character recognition is an intrinsically interesting problem, but the difficulties of this task are the many variations in the characters. A robust new incremental learning method, which combines supervised and unsupervised learning paradigms implemented by the Functional Link Net, is illustrated with experimental results. Clustering, based on unsupervised learning, classifies the input data into several categories. The supervised learning paradigm then further classifies the data in the clustered categories.

Energy Technology Data Exchange (ETDEWEB)

The electronic structure of the clusters (V/sub 3/Si/sub 4/)/sup 12 -/, (Nb/sub 3/Sn/sub 4/)/sup 12 -/(Mo/sub 3/Ge/sub 4/)/sup 15 -/ in crystalline V/sub 3/Si, Nb/sub 3/Sn, Mo/sub 3/Ge compounds is calculated by the Extended Hueckel method. The influence of different types of radiation induced defects on the density of states at the Fermi level (the anti-site defects, the displacement of atoms in linear chains, the vacancy-interstitial type defects) is considered.

International Nuclear Information System (INIS)

Extended X-ray absorption fine structure (EXAFS) measurements of bismuth clusters in the temperature range of 23 -300 K have been performed using synchrotron radiation in order to investigate the size dependent phase transition. The inter-atomic distances around 3.0 A and 3.6 A are attributed to the nearest neighbors within the layer and between layers, respectively. EXAFS functions were analysed by the curve fitting method within a symmetric distribution approximation. The nearest neighbor distance of the 0.5 nm thick films is shorter than that of the 300 nm thick films at all the temperatures, which is related to the reduction of the inter-layer correlation.

British Library Electronic Table of Contents (United Kingdom)

Phelps N. A. Cluster or capture? Manufacturing foreign direct investment, external economies and agglomeration, Regional Studies.?This paper reviews the nature and significance of external economies associated with multinational enterprise (MNE) participation in the manufacturing industries of host economies. It argues that the balance of forces of internalization and externalization is currently skewed towards the former and the interests of MNEs rather than the latter and the interests of local and national communities and governments. A stylized comparison of developmental and competition state interventions in relation to MNEs and their foreign direct investment (FDI) suggests that in the absence of co-ordinated interventions by governments, there will commonly be a failure of t...

CERN Document Server

We study a percolation process on the planted binary tree, where clusters freeze as soon as they become larger than some fixed parameter N. We show that as N goes to infinity, the process converges in some sense to the frozen percolation process introduced by Aldous. In particular, our results show that the asymptotic behaviour differs substantially from that on the square lattice, on which a similar process has been studied recently by van den Berg, de Lima and Nolin.

Energy Technology Data Exchange (ETDEWEB)

The Plant Life Assessment Network (PLAN) is a Brite Euram Type II Thematic Network, initiated by the European Commission to facilitate structured co-operation between all cost shared action projects already funded by the Commission which fall under this common technical theme. The projects involved address a multiplicity of problems associated with plant life assessment and are drawn from Brite-Euram, Standards, Measurement and Testing, Nuclear Fission Safety and Esprit EC programmes. The main aim of the Network is to initiate, maintain and monitor a fruitful co-operation process between completed, ongoing and future EC R and D projects, thereby promoting improved cross fertilization and enhanced industrial exploitation of R and D results. As the project is in its infancy, this presentation covers the background to the initiative in some detail. In particular two key aspects are highlighted, namely, the requirement of the EC to launch such a network in the area of plant life assessment ...

Energy Technology Data Exchange (ETDEWEB)

A massively-parallel ab initio computer code, which uses Gaussian bases, pseudopotentials, and the local density approximation, permits the study of transition-metal systems with literally hundreds of atoms. We present total energies and relaxed geometries for Ru, Pd, and Ag clusters with N = 55, 135, and 140 atoms; we also used the DMOL code to study 13-atom Pd and Cu clusters, with and without hydrogen. The N = 55 and 135 clusters were chosen because of simultaneous cubo-octahedral (fcc) and icosahedral (icos) sub-shell closings, and we find icos geometries are preferred. Remarkably large compressions of the central atoms are observed for the icos structures (up to 6% compared with bulk interatomic spacings), while small core compressions ({approx} 1 %) are found for the fcc geometry. In contrast, large surface compressive relaxations are found for the fcc clusters ({approx} 2-3% in average nearest ...

Energy Technology Data Exchange (ETDEWEB)

The electrochromatographic behavior of 25 metal ions on zirconium tungstate-impregnated papers is described. Six background electrolytes were used. On the basis of the differential mobilities of metal ions which depend on the ion-exchange properties of zirconium tungstate and the nature of complex formation with the electrolytes, some important binary and ternary separations have been achieved.

Energy Technology Data Exchange (ETDEWEB)

Operation at ITER specifications of the Kamaboko III ion source for 1000 second pulses of deuterium negative ion beams is underway on the MANTIS test stand. Efficient production of negative ions at low arc power requires injection of cesium into the source, temperature control of the plasma grid, and a period of conditioning of several days. Two different concepts of temperature regulated plasma grids are currently being tested. (author)

Energy Technology Data Exchange (ETDEWEB)

A general expression for the current-density distribution of a focused-ion beam (FIB) in the chromatic-aberration region is set up in the form of a definite integral. With the experimentally obtained ion-energy distribution of a liquid-metal ion source, its contribution to the FIB current-density distribution is estimated. Calculated results explain the wide-exponential tail of a FIB.

Energy Technology Data Exchange (ETDEWEB)

The apex dimensions and length are calculated as a function of current for the ion-emitting jet in liquid-metal ion sources (LMIS). The results agree well with observations. Since the final expressions are analytical, they give more insight into the fundamental mechanisms involved than do numerical calculations. Some implications of the model are discussed concerning focused ion beam (FIB) systems employing LMIS. (author).

Energy Technology Data Exchange (ETDEWEB)

In this article, the author presents the principles, applications and advantages of proton and heavy ion beams used for radiotherapy.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

British Library Electronic Table of Contents (United Kingdom)

The estimation of numerical values of the mean distance of closest approach of ions, a, of alkaline-earth metal ion salts in aqueous solutions, determined from activity coefficients, as well as from different theoretical approaches, is presented and discussed.

Energy Technology Data Exchange (ETDEWEB)

The Holifield Radioactive Ion Beam Facility (HRIBF) now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility; the choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. A high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the ...

British Library Electronic Table of Contents (United Kingdom)

The mechanism of abrupt increase of the giant magneto impedance (GMI) ratio in the ion irradiated Co-based amorphous ribbon has been investigated. The grazing incident X-ray diffraction and transmission electron microscope were used to characterize the samples before and after ion irradiation. The GMI-ratio considerably increased in the ion irradiated samples and the GMI response showed strong dependence on the driving frequencies. The Barkhausen noise (BN) signals are increased for the Ar ion irradiated sample with dose of 1x10^1^7 ion/cm^2. The results are interpreted in terms of GMI variation associated with domain wall dynamics.

CERN Document Server

In aqueous solutions, dissolved ions interact strongly with the surrounding water, thereby modifying the solution properties in an ion-specific manner. These ion-hydration interactions can be accounted for theoretically on a mean-field level by including phenomenological terms in the free energy that correspond to the most dominant ion-specific interactions. Minimizing this free energy leads to modified Poisson-Boltzmann equations with appropriate boundary conditions. Here, we review how this strategy has been used to predict some of the ways ion-specific effects can modify the forces acting within and between charged interfaces immersed in salt solutions.

Energy Technology Data Exchange (ETDEWEB)

Analytical and numerical calculations are presented for a reflexing electron beam type of collective ion accelerator. These results are then compared to those obtained through experiment. By constraining one free parameter to experimental conditions, the self-similar solution of the ion energy distribution agrees closely with the experimental distribution. Hence the reflexing beam model appears to be a valid model for explaining the experimental data. Simulation shows in addition to the agreement with the experimental ion distribution that synchronization between accelerated ions and electric field is phase unstable. This instability seems to further restrict the maximum ion energy to several times the electron energy.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

A specific radiochemical procedure for indium determination in semiconductor-grade silicon, using an inorganic ion exchanger (cerium oxalate) is proposed.

International Nuclear Information System (INIS)

... kinetics chemical reactions energy dependence ion-molecule collisions milli

UK PubMed Central (United Kingdom)

Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several...Full Text Available

International Nuclear Information System (INIS)

An overview of different Ion Beam Analysis (IBA) techniques is given. Examples of applications of the PIXE techniques to various types of samples are presented. (author)

International Nuclear Information System (INIS)

Minor M (M = Fe, Mn, Cr) additions are widely added to enhance the corrosion resistance of commercial cupronickel alloys. The present paper aims at optimizing the amounts of M in Cu_7_0(Ni,Fe,Mn,Cr)_3_0 (at.%) alloys using a cluster-plus-glue-atom model for stable solid solutions. By this model, it assumed that 1 M atom and 12 Ni atoms formed an M-centered and Ni-surrounded cube-octahedron cluster and the isolated M_1Ni_1_2 clusters are embedded in a Cu matrix, conforming to a cluster formula [M_1Ni_1_2]Cu_3_0_._3 = [M_1_/_1_3Ni_1_2_/_1_3]_3_0Cu_7_0. A structure of this kind satisfies ideally the nearest neighbor requirement, i.e. only M-Ni and Ni-Cu neighbors are allowed and the unfavorable Cu-M pairs are avoided, and hence it describes a stable solid solution structure with good thermal stability. Electrochemical corrosion measurements indicated that [(Fe_0_._6Mn_0_._2_5Cr_0_._1_5)_1Ni_1_2]Cu_3_0_._3 ...

International Nuclear Information System (INIS)

The "7Be(#alpha#,#gamma#)"1"1C and "7Li(#alpha#,#gamma#)"1"1B reactions are investigated in the three-cluster Generator Coordinate Method. The microscopic wave functions are described from #alpha# and "3He ("3H) clusters, with two coupling modes: #alpha#+"7Be ("7Li) and "3He ("3H)+"8Be. Different internal states of "7Be ("7Li) and "8Be are taken into account. The model is tested on "1"1C and "1"1B spectroscopic properties, which agree fairly well with experiment. We suggest that, in both nuclei, the (3)/(2)"- and (5)/(2)"- states located close to the #alpha#+"7Be ("7Li) threshold, are intruder states. The "7Be(#alpha#,#gamma#)"1"1C and "7Li(#alpha#,#gamma#)"1"1B reaction rates are calculated for temperatures up to 10"9 K. A strong enhancement is found with respect to the reaction rates currently used in astrophysical calculations. ((orig.)).

International Nuclear Information System (INIS)

Experimental observations related to the initiation of plastic deformation in metals and alloys irradiated with fission neutrons have been analyzed. The experimental results, showing irradiation-induced increase in the upper yield stress followed by a yield drop and plastic instability, cannot be explained in terms of conventional dispersed-barrier hardening because (a) the grown-in dislocations are not free, and (b) irradiation-induced defect clusters are not rigid indestructible Orowan obstacles. A new model called 'cascade-induced source hardening' is presented where glissile loops produced directly in cascades are envisaged to decorate the grown-in dislocations so that they cannot act as dislocation sources. The upper yield stress is related to the breakaway stress which is necessary to pull the dislocation away from the clusters/loops decorating it. The magnitude of the breakaway stress has been estimated and is found to be in good ...

CERN Document Server

We describe a clustering method for labeled link network (semantic graph) that can be used to group important nodes (highly connected nodes) with their relevant link's labels by using PARAFAC tensor decomposition. In this kind of network, the adjacency matrix can not be used to fully describe all information about the network structure. We have to expand the matrix into 3-way adjacency tensor, so that not only the information about to which nodes a node connects to but by which link's labels is also included. And by applying PARAFAC decomposition on this tensor, we get two lists, nodes and link's labels with scores attached to each node and labels, for each decomposition group. So clustering process to get the important nodes along with their relevant labels can be done simply by sorting the lists in decreasing order. To test the method, we construct labeled link network by using blog's dataset, where the blogs are the nodes and labeled links ...

CERN Document Server

NGC 1407 is the central elliptical in a nearby evolved galaxy group apparently destined to become a cluster core. We use the kinematics of globular clusters to probe the dynamics and mass profile of the group's center, out to 60 kpc (~10 R_eff) -- the most extended data set to date around an early-type galaxy. This sample consists of 172 GC velocities, most of them newly obtained using Keck/DEIMOS, with a few additional objects identified as DGTOs or as IGCs. We find weak rotation in the GC system's outer parts, with the metal-poor and metal-rich GCs misaligned. The RMS velocity profile declines rapidly to a radius of ~20 kpc, and then becomes flat or rising to ~60 kpc. There is evidence that the GC orbits have a tangential bias that is strongest for the metal-poor GCs -- possibly contradicting theoretical expectations. We construct cosmologically-motivated galaxy+dark halo dynamical models and infer a mass within 60 kpc of ~3x10^12 M_Sun, ...

Energy Technology Data Exchange (ETDEWEB)

With regard to a fracture system in the Hijiori hot dry rock artificial reservoir, an attempt was made on an interpretation which integrates different data. Major factors that characterize development and performance of an artificial reservoir are composed of a fracture system in rocks, which acts as circulating water paths, a heat exchange face and a reservoir space. The system relates not only with crack density distribution, but also with cracks activated by water pressure fracturing, cracks generating acoustic emission (AE), and cracks working as major flow paths, all of which are characterized by having respective behaviors and roles. Characteristics are shown on AE cluster distribution, crack distribution, production zone and estimated stress fields. Mutual relationship among these elements was discussed based on the Coulomb`s theory. The most important paths are characterized by distribution of slippery cracks. Directions and appearance frequencies of the ...

Science.gov (United States)

A novel multilevel hierarchical Kohonen Net (K-Map) for an intrusion detection system is presented. Each level of the hierarchical map is modeled as a simple winner-take-all K-Map. One significant advantage of this multilevel hierarchical K-Map is its computational efficiency. Unlike other statistical anomaly detection methods such as nearest neighbor approach, K-means clustering or probabilistic analysis that employ distance computation in the feature space to identify the outliers, our approach does not involve costly point-to-point computation in organizing the data into clusters. Another advantage is the reduced network size. We use the classification capability of the K-Map on selected dimensions of data set in detecting anomalies. Randomly selected subsets that contain both attacks and normal records from the KDD Cup 1999 benchmark data are used to train the hierarchical net. We use a confidence measure to label the ...

Energy Technology Data Exchange (ETDEWEB)

The relationship between the fractal dimensions of spatial distributions of aftershocks and pre-existing active faults is examined. Fourteen mainshocks taking place in Japan were followed by aftershocks, and the aftershocks occur in swarms around the mainshocks. The epicentral distributions of the aftershocks exhibit fractal properties, and the fractal dimensions are estimated by using the two-point correlation integral. The pre-existing active fault systems observed in the 14 aftershock regions have fractal structures, and the fractal dimensions are estimated by using the box-counting method. A positive correlation between the estimated fractal dimensions is found, and it is independent on the mainshock magnitude. The correlation shows that aftershock distributions become less clustered with increasing the fractal dimensions of active fault systems. Namely, the fractal clusters of aftershocks are put under the constraint of the fractal ...

CERN Document Server

One class of gravitational wave signals LIGO is searching for consists of short duration bursts of unknown waveforms. Potential sources include core collapse supernovae, gamma ray burst progenitors, and the merger of binary black holes or neutron stars. We present a density-based clustering algorithm to improve the performance of time-frequency searches for the such gravitational-wave bursts when they are extended in time and/or frequency. We have implemented this algorithm as an extension to the QPipeline search for bursts, which currently determines the statistical significance of events based solely on the peak significance observed in minimum uncertainty regions of the time-frequency plane. Density based clustering improves the performance of such a search by considering the aggregate significance of arbitrarily shaped regions in the time-frequency plane and rejecting the isolated minimum uncertainty features expected from the background ...

Energy Technology Data Exchange (ETDEWEB)

(001) CZ silicon wafers were implanted with arsenic (As{sup +}) at energies of 10--50 keV to doses of 2 {times} 10{sup 14} to 5 {times} 10{sup 15}/cm{sup 2}. All implants were amorphizing in nature. The samples were annealed at 700 C for 16 hrs. The resultant defect microstructures were analyzed by XTEM and PTEM and the As profiles were analyzed by SIMS. The As profiles showed significantly enhanced diffusion in all of the annealed specimens. The diffusion enhancement was both energy and dose dependent. The lowest dose implant/annealed samples did not show As clustering which translated to a lack of defects at the projected range. At higher doses, however, projected range defects were clearly observed, presumably due to interstitials generated during As clustering. The extent of enhancement in diffusion and its relation to the defect microstructure is explained by a combination of factors including surface recombination of point defects, As ...

CERN Document Server

Very large databases are required to store massive amounts of data that are continuously inserted and queried. Analyzing huge data sets and extracting valuable pattern in many applications are interesting for researchers. We can identify two main groups of techniques for huge data bases mining. One group refers to streaming data and applies mining techniques whereas second group attempts to solve this problem directly with efficient algorithms. Recently many researchers have focused on data stream as an efficient strategy against huge data base mining instead of mining on entire data base. The main problem in data stream mining means evolving data is more difficult to detect in this techniques therefore unsupervised methods should be applied. However, clustering techniques can lead us to discover hidden information. In this survey, we try to clarify: first, the different problem definitions related to data stream clustering in general; second, ...

CERN Document Server

We have used HST/FOS to study faint UV stars in the core of the nearby globular cluster NGC 6397. We confirm the presence of a 4th cataclysmic variable (CV) in NGC 6397 (CV 4), and we use the photometry of Cool et al. (1998) to present evidence that CVs 1--4 all have faint disks and probably low accretion rates. By combining these results with new UV spectra of CV 1 and the published spectra of Grindlay et al. (1995) we present new evidence that CVs 1--3 may be DQ Her systems, and we show that CV 4 may either be a dwarf nova or another magnetic system. Another possibility is that the CVs could be old novae in hibernation between nova eruptions. We also present the first spectrum of a member of a new class of UV bright stars in NGC 6397. These faint, hot stars do not vary, unlike the CVs, and are thus denoted as ``non-flickerers'' (NFs). Like the CVs, their spatial concentration is strongly concentrated toward the cluster center. Using stellar ...

British Library Electronic Table of Contents (United Kingdom)

Abstract We analyse extinction maps of nearby giant molecular clouds to forge a link between driving processes of turbulence and modes of star formation. Our investigation focuses on cloud structure in the column density range above the self-shielding threshold of 1-mag AV and below the star formation threshold - the regime in which turbulence is expected to dominate. We identify clouds with shallow mass distributions as cluster forming. Clouds that form stars in a less clustered or isolated mode show a steeper mass distribution. Structure functions prove inadequate to distinguish between clouds of different star formation mode. They may, however, suggest that the turbulence in the average cloud is governed by solenoidal forcing. The same is found using the -variance analysis which also in...

Energy Technology Data Exchange (ETDEWEB)

Pd-induced surface structures on Si(1 1 3) have been studied by scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). In the initial process of the Pd adsorption below 0.10 ML, Pd silicide (Pd{sub 2}Si) clusters are observed to form randomly on the surface. By increasing the Pd coverage to 0.10 ML, the clusters cover the entire surface, and an amorphous layer is formed. After annealing the Si(1 1 3)-Pd surface at 600 deg. C, various types of islands and chain protrusions appears. The agglomeration, coalescence and crystallization of these islands are observed by using high temperature (HT-) STM. It is also found by XPS that the islands correspond to Pd{sub 2}Si structure. On the basis of these results, evolution of Pd-induced structures at high temperatures is in detail discussed.

Energy Technology Data Exchange (ETDEWEB)

Potassium clusters arrayed in zeolite A are known to show ferromagnetic properties at low temperature. The origin of the spontaneous magnetization has been explained by a model of spin-canting in an antiferromagnetically ordered state. The direct information for the magnetic structure, however, has not been obtained so far. In the present work, we measure the neutron powder diffraction by using pulsed neutron source at KEK-KENS below and above the Curie temperature. No significant temperature-dependence was, however, obtained within the statistical errors, namely, magnetic scattering could not be detected separately. We also estimate the intensity of magnetic scattering by assuming some possible magnetic structures with considering the magnetic form factor of the cluster wave function. The intensity of magnetic scattering is estimated to be extremely weak and higher S/N of {approx}10{sup 4} or more is required to detect the magnetic scattering ...

Energy Technology Data Exchange (ETDEWEB)

We demonstrate that the nanoparticle formation during laser ablation of metals by short (of a few tens of ps) laser pulses strongly depends on the concentration of surrounding gas. While, at vacuum conditions, nanoparticle formation shows very ''sharp'' atomic force microscope images of aggregated clusters, following with clear appearance of plasmon resonance on the absorption spectra of deposited films, an addition of gas particles starts to decrease the probability of cluster formation. This process shows a threshold for both helium (33 torr) and xenon (12 torr) above which no surface plasmon resonance and correspondingly no observable nanoparticles on the deposited surfaces were detected. The destruction of nanoparticle formation was attributed to the negative influence of surrounding gas particles on ablated particles aggregation. (orig.)

International Nuclear Information System (INIS)

We have measured K-edge X-ray absorption spectra of argon in sputtered aluminum films at a synchrotron radiation facility (the Photon Factory). We found that the energy and shape of white line change when the film is annealed at 500 C and the spectrum becomes resembling that of argon implanted in silicon. From the analyses of the X-ray absorption spectra and TEM observation we concluded that argon exists as very small atom clusters with a diameter less than 1 nm or exist as isolated atoms in the as-sputtered aluminum film, and that the size of the clusters become as big as 10 nm diameter when the film is heated. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

British Library Electronic Table of Contents (United Kingdom)

The dynamics of state of the crystallite-containing magma is studied within the framework of the gas-dynamic model of bubble cavitation. The effect of crystallites on flow evolution is considered for two cases: where the crystallites are cavitation nuclei (homogeneous-heterogeneous nucleation model) and where large clusters of crystallites are formed in the magma in the period between eruptions. In the first case, decompression jumps are demonstrated to arise as early as in the wave precursor; the intensity of these jumps turns out to be sufficient to form a series of discrete zones of nucleation ahead of the front of the main decompression wave. Results of experimental modeling of an explosive eruption with ejection of crystallite clusters (magmatic ?bombs??) suggest that a cocurrent flow...

British Library Electronic Table of Contents (United Kingdom)

An ultrafine-grained ferrite/cementite (UGF/C) steel with a local high density of cementite particles was fabricated through caliber-warm-rolling followed by annealing and resulted in a bimodal-sized microstructure. The characteristic bimodal-sized microstructure was attributed to the original ferrite-pearlite structure and cementite spacing, and reflected the original ferrite-pearlite structure. The smaller-sized clusters corresponded to the former pearlite regions and the larger-sized clusters to the proeutectoid ferrite regions. The cementite particles naturally localized within the former pearlite region. Most of the ferrite coarsening did not occur until the cementite particle spacing reached a critical value. The UGF/C microstructure with a bimodal grain size showed a yield strength ...

International Nuclear Information System (INIS)

By method of transmission electron microscopy and measuring of microhardness the peculiarities of influence of radiation defect clusters on molybdenum radiation hardening along range path of protons with 30 MeV initial energy are studied. Decrease effect of hardening growth value and even its absence depending on irradiation dose in the range of 10-20 MeV proton energies in presence of high density of radiation defect dispersed clusters is revealed. It is shown experimentally that this effect is connected with accumulation of hydrogen up to not very high concentrations (not more than 5x10"-"4 at.%) at the expense of elastic and inelastic proton scattering. 5 refs.; 5 figs.

Energy Technology Data Exchange (ETDEWEB)

A deep band of {l_brace}311{r_brace} defects was created 520 nm below the silicon surface with a 350 keV Si implant followed by a cluster-forming rapid thermal anneal (800 C, 1000 s). Chemical etching was used to vary the depth to the surface of the {l_brace}311{r_brace}-defect band. Afterwards, the defect dissolution was investigated at 750 C for different times. Varying the depth in this fashion assures that only the depth and no other feature of the cluster distribution is changed. The {l_brace}311{r_brace} defects were analyzed by plan-view, transmission electron microscopy. We show that the dissolution time of the {l_brace}311{r_brace}-defect band varies linearly with depth, confirming that surface recombination controls the dissolution and is consistent with analogous observations of transient enhanced diffusion.

British Library Electronic Table of Contents (United Kingdom)

The magnetic three spin-1/2 model for nanometer-scale molecular cluster V15 is analyzed with the emphasis on the origin of the mixing of different spin levels in the resonance fields that is generally important for the problem of single molecular magnets. The zero-field splitting in the ground quadruplet (two Formula Not Shown levels) is shown to depend mainly on the normal component of AS exchange meanwhile the zero-field splitting in the excited Formula Not Shown multiplet is a second order effect with respect to in-plane components of AS exchange. The normal component of the AS exchange is shown to lead to the exact crossing of the magnetic sublevels at the arbitrary direction of the field. The positions of two crossing/anticrossing points in the ground manifold depend mainly on the iso...

International Nuclear Information System (INIS)

This investigation of a brain cancer cluster in Missouri used two approaches to investigate associations with potential risk factors. In a case-control study in a rural town, we interviewed surrogates of cases and controls about potential risk factors. We found a statistically significant positive association of brain cancer with reported exposure to dental x-rays. Occupation was not associated with the cluster in the rural town. In a standardized proportional mortality study for the state of Missouri, we calculated the observed and expected proportion of brain cancers by occupation and industry in Missouri decedents. We found that motor vehicle manufacturers, beauty shop workers, managers and administrators, elementary school teachers, and hairdressers and cosmetologists had significantly elevated proportions of brain cancer. Brain tumors are inconsistently associated with occupation in the literature. Further study of brain cancer etiology ...

Science.gov (United States)

The Plasma and Ion Source Technology Group at the Lawrence Berkeley National Laboratory have been developing rf-driven ion sources for the last two decades. These sources are being used to generate both positive and negative ion beams. Some of these sources are operating in particle accelerators such as the Spallation Neutron Source (SNS) at Oak Ridge, while others are being employed in various industrial ion beam systems. There are four areas where the rf-driven ion sources are commonly used in industry. (1) In semiconductor manufacturing, rf-driven sources have found important applications in plasma etching, ion beam implantation, and ion beam lithography. (2) In material analysis and surface modification, miniature rf-ion sources can be found in focused ion beam systems. They can provide ...

Energy Technology Data Exchange (ETDEWEB)

Neutral beam systems for the next generation of magnetic fusion devices will be based on negative ions. Developments are progressing steadily, and large negative ion-based systems are under preparation for JT60-U and LHD, and are being considered for ITER. An overview of the physics of the production, acceleration and neutralization of large negative ion beams is given. The present state of the art in R and D is also surveyed. (Author).

Energy Technology Data Exchange (ETDEWEB)

A summary of the topics covered in papers presented at the 1995 Brookhaven joint conference on production, neutralization, and application of negative ion beams is given. The conference topics covered included plasma ion sources, plasma seeding of these sources for increased ion production, beam extraction and transport, computer simulation and design studies, and operation of existing and experimental ion source facilities. Application of the sources to accelerator, tokamak, and thin film deposition are discussed. (AIP) {copyright} {ital 1996 American Institute of Physics.}

Energy Technology Data Exchange (ETDEWEB)

The Holifield Radioactive Ion Beam Facility now under construction at the Oak Ridge National Laboratory will use the 25 MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility. The choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. Although direct-extraction negative ion sources are clearly desirable, the ion formation efficiencies are often too low for practical consideration; for ...

International Science & Technology Center (ISTC)

Development of Oxygen Ion-Implanted Collector materials for Thermal Emission Converters of Thermal Energy into the Electric One.

Energy Technology Data Exchange (ETDEWEB)

Negative ion intensities of over 3 x 10/sup 5/ A/m/sup 2/ at energies of 2 MeV have been measured in a magnetically insulated transmission line. This negative ion production can affect the power flow in multiterawatt pulsed power devices, and may also have applications in the generation of high-intensity neutral or negative ion beams.

International Nuclear Information System (INIS)

This report is a brief review of biological and medical applications of ion-track membranes. The review aims at informing nuclear physicists about alternative (i.e. non-fundamental-science) use of heavy ion accelerators such as production of micro- and nano-porous materials. The ion-track membranes produced this way are employed in life sciences and numerous technological applications. The author focuses on recent results from the Flerov laboratory in co-operation with other scientific institutions and industrial partners.

KoreaScience (Korea)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

Results are described of the study of the analytical applicability of a highly efficient ion source developed for a mass spectrometer. Its ionizer is in the form of a partially closed cavity with a small aperture for leading out ions, heated to a high temperature. The new ion source increases the sensitivity of the apparatus in operations with transuranium elements by almost two orders of magnitude. It is possible to perform isotopic analyses with a high salt content in the sample, and to study the characteristics of nuclear fuel, even without chemical separation of the sample elements.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.