bluuebunny/crossref_metadata_2025 huggingface dataset:
Do different implant surfaces exposed in the oral cavity of humans show different biofilm compositions and activities?
Authors: Groessner‐Schreiber Birte , Hannig Matthias , Dück Alexander , Griepentrog Michael , Wenderoth Dirk F.
Published: November 2004

Osseointegrated dental implants play an important role in restorative dentistry. However, plaque accumulation may cause inflammatory reactions around the implants, sometimes leading to implant failure. In this in vivo study the influence of two physical hard coatings on bacterial adhesion was examined in comparison with a pure titanium surface. Thin glass sheets coated with titanium nitride (TiN), zirconium nitride (ZrN) or pure titanium were mounted on removable intraoral splints in two adults. After 60 h of intraoral exposure, the biofilms were analyzed to determine the number of bacteria, the types of bacteria [by applying single‐strand conformation polymorphism (SSCP analysis) of 16S rRNA genes], and whether or not the bacteria were active (by SSCP analysis of 16S rRNA). The results showed that bacterial cell counts were higher on the pure titanium‐coated glass sheets than on the glass sheets coated with TiN or ZrN. The lowest number of bacterial cells was present on theZrN‐coated glass. However, the metabolic activity (RNA fingerprints) of bacteria on TiN‐ and ZrN‐coated glass sheets seemed to be lower than the activity of bacteria on the titanium‐coated surfaces, whereas SSCP fingerprints based on 16S rDNA revealed that the major 16S bands are common to all of the fingerprints, independently of the surface coating.
Influence of drinking method on tooth‐surface pH in relation to dental erosion
Authors: Johansson Ann‐Katrin , Lingström Peter , Imfeld Thomas , Birkhed Dowen
Published: November 2004

The aim of this investigation was to study the intraoral pH response on tooth surfaces in relation to dental erosion during and after drinking a sugar‐free cola‐type soft drink. Six different methods of drinking were tested in a randomized order: holding; short‐sipping; long‐sipping; gulping; nipping; and sucking. Two methods of pH measurement were used in two series of individuals. In the first series, pH was measured by using the microtouch method in 12 healthy adults at three dental erosion‐prone sites: 11 palatally; 11 buccally; and at the mesiobuccal cusp tip of 16. In the second series, pH was measured by using the telemetric method in 6 healthy individuals, producing continuous recordings of pH by means of a glass electrode in a specified approximal area. The two series showed similar results, although the telemetric method generally recorded larger pH falls. Holding the drink in the mouth before swallowing led to the most pronounced pH drop, followed by the long‐sipping method. Gulping resulted in only a small decrease of pH. No differences among the three intraoral sites were found when analyzed by using the microtouch method. The conclusion from this study is that the drinking method strongly affects tooth‐surface pH and thereby the risk for dental erosion. It therefore seems appropriate to include advice on the method of drinking in dietary counseling related to dental erosion.
Comparative fluorescence spectroscopy of root caries lesions
Authors: Buchalla Wolfgang , Lennon Áine M. , Attin Thomas
Published: November 2004

In this study, the light‐emission properties of carious and sound root surfaces were investigated under a wide range of excitation wavelengths. Human molar teeth with exposed root surfaces containing light‐ and dark‐discolored root caries (n = 3 of each) were selected. Emission spectra were recorded from carious and corresponding sound root surface areas from each tooth by using a fluorescence spectrophotometer at excitation wavelengths from 360 nm up to 580 nm, in steps of 20 nm. The spectra were corrected for fluctuations in detector sensitivity and excitation light intensity, and normalized to peak intensity. Excitation spectra were recorded for selected emission wavelengths that showed maximum intensity. Light‐ and dark‐discolored root surface caries showed distinct fluorescence emission bands between 600 and 700 nm that were not present in sound root surface areas. These bands were strongest for excitation wavelengths between 390 and 420 nm. The excitation spectra of root caries revealed maximum excitation at around 405 nm, which is equivalent to the Soret band of porphyrin compounds. The emission spectra of both types of root caries lesions were shifted towards longer wavelengths (red shift at half maximum) when compared to the spectra of corresponding sound root surfaces. The red shift for dark‐discolored root caries was higher than for light‐discolored lesions at all excitation wavelengths.
Molecular analyses of the candidate tumor suppressor gene, PLAGL1, in benign and malignant salivary gland tumors
Authors: Enlund Fredrik , Persson Fredrik , Stenman Göran
Published: November 2004

Deletions affecting the long arm of chromosome 6 are a characteristic feature of all major subtypes of malignant salivary gland tumors. Moreover, a subgroup of adenoid cystic carcinomas have t(6;9)(q23‐25;p21‐24) translocations with breakpoints located within the commonly deleted region. Here we have examined the possible involvement of the candidate tumor suppressor gene, PLAGL1, in these deletions and translocations. Northern blot and fluorescence in situ hybridization (FISH) analyses of a series of 27 salivary gland tumors revealed no significant changes in the gene expression or rearrangements of PLAGL1. FISH analysis also demonstrated that the 6q translocation breakpoint in adenoid cystic carcinomas with t(6;9) is proximal to the PLAGL1 locus. Collectively, these results indicate that PLAGL1 is not likely to be the major target gene of the 6q rearrangements in salivary gland tumors.
Modulation of Swarming and Virulence by Fatty Acids through the RsbA Protein inProteus mirabilis
Authors: Liaw Shwu-Jen , Lai Hsin-Chih , Wang Won-Bo
Published: November 2004

After sensing external signals,Proteus mirabilisundergoes a multicellular behavior called swarming which is coordinately regulated with the expression of virulence factors. Here we report that exogenously added fatty acids could act as signals to regulate swarming inP. mirabilis. Specifically, while oleic acid enhanced swarming, some saturated fatty acids, such as lauric acid, myristic acid, palmitic acid, and stearic acid, inhibited swarming. We also found that expression of hemolysin, which has been shown to be coordinately regulated with swarming, was also inhibited by the above saturated fatty acids. Previously we identified a gene,rsbA, which may encode a histidine-containing phosphotransmitter of the bacterial two-component signaling system and act as a repressor of swarming and virulence factor expression inP. mirabilis. We found that while myristic acid, lauric acid, and palmitic acid exerted their inhibitory effect on swarming and hemolysin expression through an RsbA-dependent pathway, the inhibition by stearic acid was mediated through an RsbA-independent pathway. Biofilm formation and extracellular polysaccharide (EPS) production play an important role inP. mirabilisinfection. We found that RsbA may act as a positive regulator of biofilm formation and EPS production. Myristic acid was found to slightly stimulate biofilm formation and EPS production, and this stimulation was mediated through an RsbA-dependent pathway. Together, these data suggest that fatty acids may act as environmental cues to regulate swarming and virulence inP. mirabilisand that RsbA may play an important role in this process.
MULTIDIMENSIONAL DIGITAL SEARCHING AND SOME NEW PARAMETERS IN TRIES
Authors: KIRSCHENHOFER PETER , PRODINGER HELMUT , SZPANKOWSKI WOJCIECH
Published: November 2004

Multidimensional digital searching (M-d tries) is analyzed from the view point of partial match retrieval. Our first result extends the analysis of Flajolet and Puech of the average cost of retrieval under the Bernoulli model to biased probabilities of symbols occurrences in a key. The second main finding concerns the variance of the cost of the retrieval in the unbiased case. This variance is of order O(N1−s/M) where N is the number of records stored in an M-d trie, and s is the number of specified components in a query of size M. For M=2 and s=1 we present a detailed analysis of the variance, which identifies the constant at [Formula: see text]. This analysis, which is the central part of our paper, requires certain series transformation identities which go back to Ramanujan. In the Appendix we provide a Mellin transform approach to these results.
HISTORICAL SEARCHING
Authors: MOFFAT ALISTAIR , PETERSSON OLA
Published: November 2004

When searching for an item x in a dictionary, let t be the number of distinct items referenced since the previous reference to x. The move-to-front-list is a widely known dictionary data structure that supports searches on x in O(t) time. We present a new selforganizing data structure, called the Historical Search Tree, which supports the search in O( log t) time, and thus exploits the temporal locality more efficiently. The Historical Search Tree also handles unsuccessful searches, insertions, and deletions efficiently. We further show how the data structure can be modified to take advantage of spatial locality.
COMPLEXITY OF UNIVERSAL CIRCUMSCRIPTION
Authors: LISITSA ALEXEI P.
Published: November 2004

The computational problem of model checking for circumscription of first-order formulae is studied. It is shown that there is a universal first-order formula whose circumscription has coNP-complete model checking problem. This answers a question raised by P.H. Kolaitis and C.H. Papadimitriou.
A TOP-DOWN UPDATING ALGORITHM FOR WEIGHT-BALANCED TREES
Authors: LAI TONY W. , WOOD DERICK
Published: November 2004

We prove that during any update in a weight-balanced tree, or BB[α] tree, a top-down restructuring pass is sufficient to rebalance the tree if 2/11<α≤1/4. We also prove that if updates are known to be nonredundant, then a top-down pass is sufficient to rebalance the tree during an update if [Formula: see text].
REDUNDANCY AND THE JUSTIFICATION FOR FOURTH NORMAL FORM IN RELATIONAL DATABASES
Authors: VINCENT MILLIST W. , SRINIVASAN BALA
Published: November 2004

The relationship between the absence of redundancy in relational databases and fourth normal form (4NF) is investigated. A relation scheme is defined to be redundant if there exists a legal relation defined over it which has at least two tuples that are identical on the attributes in a functional dependency (FD) or multivalued dependency (MVD) constraint. Depending on whether the dependencies in a set of constraints or the dependencies in the closure of the set is used, two different types of redundancy are defined. It is shown that the two types of redundancy are equivalent and their absence in a relation scheme is equivalent to the 4NF condition.
APPLICATION OF PIXE TO SEPARATION SCIENCE - TRACE ELEMENT ANALYSIS BY A COMBINED METHOD, ISOTACHOPHORESIS-PIXE -
Authors: HIROKAWA TAKESHI , KISO YOSHIYUKI
Published: November 2004

Recent studies were reviewed on the PIXE analysis of metal ions preseparated by means of capillary type isotachophoresis (ITP-PIXE). The principle was described of isotacho-phoresis which was one of electrophoretic methods with high separability and concentration ability. Some applications of ITP-PIXE were demonstrated on the investigation of the separation behavior of metal ions and the analysis of trace elements in a crude rare earth chloride from a monazite and a model mixture of a high level liquid waste. It was revealed that PIXE could be a powerful detection method for the fractions of isotacho-phoresis because of its high sensitivity and multielemental analyzability. Since the matrix effect in X-ray measurement was significantly reduced by such preseparation, the minor elements could be determined accurately.
K-SHELL X-RAY PRODUCTION BY PROTONS IN VACUUM AND GASEOUS ENVIRONMENT
Authors: KALLITHRAKAS-KONTOS N. , KATSANOS A.A.
Published: November 2004

The yields of Kα x-ray production from the bombardment of metal targets with protons were measured in vacuum and in gaseous environment (external beam technique) for proton energies between 1.5 and 8 MeV. For the measurements in gaseous environment the influence of the secondary electrons (delta electrons) emitted from the gas, to the x-ray yields was investigated. For this purpose a suitable model was introduced and tested experimentally. Finally, the experimental K shell ionization and x-ray production cross sections were calculated for the same targets and compared with three theoretical and two semiempirical approximations.
PROTON ACTIVATION ANALYSIS (PAA): A COMPLEMENT TO PIXE AND PIGE ANALYSIS
Authors: HALDEN NORMAN M. , HAWTHORNE FRANK C.
Published: November 2004

At E p =40 MeV , protons have sufficient energy to overcome the coulomb barrier of most elements. The resultant interaction between protons and nucleii of many can produce radioactive isotopes via nuclear reactions. The decay schemes of isotopes created in this manner may include the emission X-rays and gamma-rays that can provide useful analytical information.
ANALYSIS OF TRACE RARE EARTH ELEMENTS IN MISCH METAL BY MEANS OF ITP-PIXE METHOD
Authors: HU JIAN-YING , HIROKAWA TAKESHI , NISHIYAMA FUMITAKA , KIMURA GOJI , KISO YOSHIYUKI , ITO KAZUAKI , SHOTO EIJI
Published: November 2004

A misch metal, an alloy of light rare earth elements, was analyzed by a new coupled analytical method, ITP-PIXE(isotachophoresis—Particle Induced X-ray Emission) : The sample solution containing ca.1 mg misch metal was separated and fractionated by the use of a preparative isotacho-phoretic analyzer. The dropwise fractions containing nanomole rare earth elements were analyzed off-line by PIXE. The matrix effect in X-ray measurement was reduced by the isotachophoretic removing of the dominant lanthanoids and preconcentration of the trace elements of interest. Consequently the minor elements, Sm, Gd, Tb, Dy, Ho, Er, Yb and Y could be determined accurately. The most trace element found was Yb (4ppm, 4ng in 1mg sample). The good accuracy of ITP-PIXE method was also demonstrated for several model samples of lanthanoids, where La was the dominant element and the thirteen lanthanoids were the minor elements. The ratio was varied from 500:1 to 50000:1. Even in the case of 50000:1, ca. 10% accuracy was achieved for each minor element except for Sm(23%), Gd(17%) and Yb(18%). The analytical results by ITP-PIXE were compared with those by means of ICP-AES(Inductively Coupled Plasma—Atomic Emission Spectrometry).
PIXE MICROANALYSIS OF VERY LOW Z ELEMENTS BY SUB MeV PROTON BEAM
Authors: EL-GHAWI USAMA M.
Published: November 2004

Analysis of very low Z elements between Be and Si using sub MeV proton beam is explored based on theoretical calculations and supported by experimental data. With the availability of the new LE Ge detector, Be K α X-rays can be recorded with reasonable efficiency and high resolution. PWBA and the modified theory, ECPSSR, have been used for ionization cross-section calculation. Minimum detection limits (MDL’s) for thin target conditions are presented in the energy range of 150–2500 keV.
HIGH-ENERGY PIXE: THE X-RAY SPECTRUM OF URANIUM IN AUTUNITE
Authors: HALDEN NORMAN M. , HAWTHORNE FRANK C.
Published: November 2004

Autunite, a U-bearing mineral ( Ca(UO) 2( PO 4)2.10–12 H 2 O ), has been examined using a high-energy proton beam ( E p =40 MeV ) and Si(Li) and intrinsic Ge solid state detectors. The spectra obtained from the sample show clearly resolved U K α1, K α2 and K β X-ray lines (using the Ge detector) and Ca K α, K β X-rays, Sr K α, K β and U L X-rays (using the Si(Li) detector), this demonstrates the potential analytical range and flexibility of high energy PIXE analysis.
PIXE ANALYSIS OF RARE EARTH ELEMENTS
Authors: Jimenez-Reyes M.
Published: November 2004

In this paper a review of data from the available literature on the REE analysis by PIXE is presented. General comments, a discussion of essentials, and a survey of applications are also included.
CHARACTERISTIC FEATURES OF Lγ1 X-RAYS IN Nb METAL AND COMPOUNDS AND COMPARISON WITH AMORPHOUS ALLOYS
Authors: IIHARA J. , YOSHIHARA K.
Published: November 2004

It was revealed that by high resolution x-ray measurements that the L γ1 spectra of metallic Nb and Nb-Ni amorphous alloys showed only one broad peak, while those of NbC and NbN had two components. The reason why the amorphous alloys had FWHM’s broader than that in Nb metal was explained by the formation of a mixed band from Nb-4d and Ni-3d electrons. Proton excitation of Nb metal and alloys resulted a smaller L γ1/ L β1 intensity ratio compared to electron or x-ray excitation. Possible interpretation of this difference has been proposed.
A TRACE ELEMENT STUDY OF POWDERED MILK BY PIXE
Authors: DESALES-GALEANA G. , TENORIO D. , JIMENEZ-REYES M. , MAGGI R. , LOPEZ-MONROY J.
Published: November 2004

PIXE analysis of 10 commercial powdered milk has been performed for 16 elements: P, Cl, K, Ca, Cr, Fe, Co, Ni, Cu, Zn, Ga, Br, Rb, Sr, Mo and Cd. None of the analyzed samples was found to contain any of these elements at concentrations exceeding toxicity limits. A qualitative analysis of the powdered milk containers was also done. Analysis of a standard reference milk sample, A-11 from IAEA, for the 16 elements listed above gave a good agreement with the certified values, except for Cl, K, Ca, Cr and Rb.
SOME APPLICATIONS OF LOW ENERGY ACCELERATORS
Authors: BUDNAR M.
Published: November 2004

Accelerators producing ions with energies up to few MeV/amu have been extensively used in the past twenty years mainly in the atomic physics research and its several applications.

The investigations first oriented towards the study of the inner-shell ionization through the Z1≪Z2 collisions, moved to the analysis of Z1~Z2 and Z1≫Z2 processes. Several mechanisms including direct Coubmb ionization (Dl), molecular orbital (MO) processes and transfer interaction (TE) excitations were studied this way. The observations of these phenomena stirred up possible explanations and gave deeper insight into the behaviour of the atomic electrons and their mutual correlations. Also several decay channels corresponding to the diagram processes and to the second order effects like satellites, hypersatellites, RAE, RER, etc. have been studied extensively for better understanding of the atomic physics phenomena.

Based on the fundamental research, frequent applications using ions as the main research tool emerged. Here methods for the elemental concentrations determination as PIXE, µPIXE, RBS, PIGE and others are most known. Also the use of some of them for the profiling and the surface analysis is important. Above mentioned methods are now extensively and routinely used in several laboratories for environmental studies, material analysis, biomedical research and in other fields.
HIGH-SPEED ANALYSIS TECHNIQUE FOR GAMMA-RAY AND X-RAY SPECTRA USING AN ASSOCIATIVE NEURAL NETWORK
Authors: IWASAKI S. , FUKUDA H. , KITAMURA M.
Published: November 2004

A new technique for gamma-ray and X-ray spectral analyses is described. It employs an artificial neural network in order to meet requirements of easiness, compactness and promptness of the analysis. This technique only needs a suitable set of component spectra for the network training. Performance test of the network shows good results for gamma-ray spectra obtained by a 3"×3" NaI(Tl) spectrometer, and both for gamma- and X-ray spectra obtained with an 80cc high purity germanium detector. Degradation conditions and applicability to a PIXE analysis are discussed.
PRESENT STATUS OF NMCC AND SAMPLE PREPARATION METHOD FOR BIO-SAMPLES
Authors: FUTATSUGAWA S. , HATAKEYAMA S. , SAITOU S. , SERA K.
Published: November 2004

In NMCC(Nishina Memorial Cyclotron Center) we are doing researches on PET of nuclear medicine (Positron Emission Computed Tomography) and PIXE analysis (Particle Induced X-ray Emission) using a small cyclotron of compactly designed. The NMCC facilities have been opened to researchers of other institutions since April 1993. The present status of NMCC is described.

Bio-samples (medical samples, plants, animals and environmental samples) have mainly been analyzed by PIXE in NMCC. Small amounts of bio-samples for PIXE are decomposed quickly and easily in a sealed PTFE (polytetrafluoroethylene) vessel with a microwave oven . This sample preparation method of bio-samples also is described.
DESIGN OF AN ULTRA COMPACT CYCLOTRON FOR PARTICLE INDUCED X-RAY EMISSION
Authors: WAKASA S. , FUKUDA K. , TAKAGI T. , NAKANISHI N.
Published: November 2004

An ultra compact cyclotron was constructed for Particle Induced X-ray Emission (PIXE) and Rutherford Back Scattering (RBS) experiments. The cyclotron accelerates proton and alpha-particle beams to a constant energy of 3 MeV. The size of the magnet is 85 cm ×85 cm ×60 cm . Characteristics of the cyclotron are presented.
MODEL AND METHODS FOR REGULAR ARRAY DESIGN
Authors: DEPRETTERE ED F. , HELD PETER , WIELAGE PAUL
Published: November 2004

We present a unified framework for the transformation of algorithms to architectures in the domains of high speed signal and algebraic processing. The framework starts from algorithmic specifications in a language suited for numerical analysis (such as Matlab), transforms the high level description into hierarchical and structured data flow dependence graphs, allows the designer to manipulate the graphs, to merge them, abstract them, regularize them, cluster and partition them etc… until the description of an architecture which can represent the hardware in a precise manner is obtained. A generic model for hierarchical, parametrized descriptions assures a consistent design methodology throughout. In the process, we not only generate attractive parallel architectures based on a fixed array of processing elements, but also their control and the program that has to be executed by the host processor. Because of the parametrization, the designs are "generic" and hence reusable, but they are restricted to cases where the parameters are known at "generation time".
NET-REGULAR PLACEMENT FOR HIGH PERFORMANCE CIRCUITS
Authors: YEAP KOK-HOO , SARRAFZADEH MAJID
Published: November 2004

We examine a placement strategy incorporating the knowledge of underlying circuit structure targeted for high performance circuits. We measure the "net regularity" using the standard deviation of the locations of its terminals. Experimental results showed that exploiting circuit structural information led to substantially more regular nets, compared to placement without structural information. Benchmark circuits from MCNC showed 1.9 to 26 times increase in the number of nets with zero standard deviation. Furthermore, the length of the longest net in a chip was reduced from 5 to 22%. The placement strategy is crucial for high performance circuits since regular nets have relatively fewer vias and reducing the longest net length improves signal delay.
SUPER-POWER FREE ELECTRON LASERS WITH TWO-DIMENSIONAL DISTRIBUTED FEEDBACK
Authors: GINZBURG N. S. , YU. PESKOV N. , SERGEEV A. S.
Published: November 2004

To realize spatially coherent radiation from a sheet relativistic electron beams with transverse dimensions essentially exceeding the wavelength, we propose the use of two-dimensional distributed feedback. This feedback can be provided in a Bragg resonator formed by two double-periodic corrugating metal plates, when additional transverse electromagnetic energy fluxes that synchronize the radiation of individual parts of the electron beam take place. It is found that eigenmodes of a 2-D Bragg resonator and proved its high selectivity. Numerical simulation of excitation of a 2-D Bragg resonator by sheet relativistic electron beam and oscillation build-up demonstrates the possibility to provide spatially coherent radiation to a beam of width 102 – 103 wavelengths. The concept of superpower FEL (P ≃ 20 GW ) in the millimeter wave range is discussed.
THE THEORY OF FREE ELECTRON LASERS WITH AXIAL GUIDE MAGNETIC FIELD
Authors: GINZBURG N. S. , NOVOZHILOVA YU. V. , YU. PESKOV N.
Published: November 2004

Amplification and generation schemes of free electron lasers with a helical undulator and homogeneous guiding magnetic field are considered. A description of the process of pumping bounce oscillations of electrons in the adiabatically tapered undulator field is presented. The electron beam interacts with the electromagnetic wave in the region of constant amplitude of the undulator field where electrons move along stationary helical trajectories. Linear and nonlinear theory of such interaction is developed when electrons are under the undulator and combined synchronism with the electromagnetic wave. In the latter case the radiation is accompanied by excitation of electron oscillations near the equilibrium trajectory. A range of parameters for undulator synchronism is found where a considerable Doppler frequency up-conversion can be realized simultaneously with high efficiency (for amplifiers more then 30%). The mechanism of efficiency enhancement in this region is described. The influence of HF space charge (including negative mass effects) and the transverse inhomogeneity of the undulator field is discussed.
THE INVERSE OF A CR-HOMEOMORPHISM IS CR
Authors: DIEDERICH KLAS , PINCHUK SERGEY
Published: November 2004

Let Ω, [Formula: see text] be domains and M ⊂ Ω, M′ ⊂ Ω′ be C2-smooth relatively closed real hyper-surfaces. The main result of the article is:

Theorem. Let f: M → M′ be a homeomorphic CR-mapping. Then the inverse mapping f−1: M′ → M is also CR.

As one of the main tools in the proof of this theorem the following removable singularity result for continuous CR-functions on real hypersurfaces is derived (it also might be useful for other applications):

Theorem.Let [Formula: see text] be a family of closed complex hypersurfaces in M. Put [Formula: see text]. Suppose that h is a continuous function on M which is CR in a neighborhood of each point [Formula: see text] and such that the restriction h\Sα is holomorphic for all α ∈ A. Then h is CR on M.
ANOSOV OBSTRUCTIONS IN HIGHER DIMENSION
Authors: HASSELBLATT BORIS
Published: November 2004

In some cases the Anosov cocycle of Hurder and Katok can be found in higher dimensional symplectic systems as well.
L2-BOUNDEDNESS OF NON-CONVOLUTION TYPE g-FUNCTION OPERATORS ON PRODUCT DOMAINS
Authors: LONG R.
Published: November 2004

In this paper, we use the theorem of T (b) type on product domains given in Long-Zhu [4], to obtain the L2-boundedness of the non-convolution type g-function operators on product domains.
A PARALLEL RAYCAST ALGORITHM OF CSG MODELS ON CM2
Authors: PILI PIERO
Published: November 2004

One of the main problems for CSG models manipulators is the fast visualization of the results. The high computational cost on single-processor architectures makes the CSG scheme useless for the interactive creation of the model.

This article deals with a parallel algorithm based on general purpose SIMD architecture, such as the Connection Machine 2, for the visualization of high quality shaded images of CSG models in nearly real time.

The technique is based on a pixels parallelization of the Ray Casting algorithm. The Frame Buffer is divided into severals regions and for each of them we determine the CSG reduced model projected on it. Then a processor is assigned to each pixel in the sub-area; it determines the equation of the ray crossing the pixel and, using the Ray Casting technique, the nearest intersection point to the pixel on which it calculates the illumination model.
PARALLEL COMPUTER GRAPHICS AT THE INSTITUTE OF AUTOMATION
Authors: WANG DONG CHEN , MÖLLER REINHARD , CARL UWE , PRISLAN OLIVER , SENGOTTA THOMAS , RITTER P.
Published: November 2004

The current research activities on the Connection Machine concerning parallel computer graphics in the Institute of Automation is shortly presented. Two major research subjects are reported which range from realistic computer graphics to graphical robot simulation. Especially, the router communication problem is discussed which has significant influences upon the performance. The results can also be applied to similar computational tasks.
AB-INITIO THEORETICAL APPROACHES TO THE STRUCTURAL, ELECTRONIC AND VIBRATIONAL PROPERTIES OF SMALL CLUSTERS AND FULLERENES: THE STATE OF THE ART
Authors: ANDREONI WANDA
Published: November 2004

A brief report is presented of recent advances in the theoretical study of clusters and fullerenes with ab-initio methods. Selected calculations of structural properties, excited electronic states and vibrational spectra will be discussed. The purpose is to compare different methods and clarify their specific powers and weaknesses.
DECOUPLING TRANSFORMATION APPROACH TO LATTICE DYNAMICS IN FACE-CENTRED CUBIC METALS
Authors: CHOY T. L. , YEUNG Y. Y.
Published: November 2004

The Decoupling Transformation is applied to study various lattice dynamical properties of face-centred cubic metals after it is reformulated in terms of the Cyclic Region Group. The theory is established and illustrated with a running example — copper. Unique set of force constants representing interaction between intersublattices are tabulated and compared to the traditional least-squares fit results. A computer package is developed for deriving those force constants as well as for constructing the phonon spectrum based on the decoupling transformation approach. Further discussion on the approach and the results are also presented.
ISOTHERMAL MOLECULAR DYNAMICS: A PRACTICAL STUDY
Authors: FATTEBERT JEAN-LUC , BONOMI ERNESTO
Published: November 2004

In a molecular dynamics simulation, trapping of the phase space trajectory can occur at low energy for long time intervals. To untrap that evolution and recover the canonical ensemble description, at regular clock hits, all particle velocities are randomly redistributed according to the Maxwell statistics. The organization of this hybrid evolution mixing molecular dynamics and random number generation leads to a fully parallel and synchronous algorithm.

An illustration of this approach on the one-dimensional jellium is presented. For large values of the coupling λ for which the evolution at constant energy is trapped, the hybrid method allows to reproduce the exact Boltzmann statistical description. Computer simulations show that the Nosé-Hoover method does not really improve the pure molecular dynamics for the one dimensional jellium.
HEAT-KERNEL CALCULATION OF QUARK DETERMINANT AND COMPUTER ALGEBRA
Authors: BEL'KOV A. A. , EBERT D. , LANYOV A. V. , SCHAALE A.
Published: November 2004

In this paper we describe the calculational background of deriving a strong meson Lagrangian from the Nambu–Jona-Lasinio quark model using the computer algebra systems FORM and REDUCE in recursive algorithms, based on the heat-kernel method for the calculation of the quark determinant.
DEVELOPMENT OF A GAUSSIAN HYPERGEOMETRIC FUNCTION CODE IN COMPLEX DOMAINS
Authors: HSU YUPAI P.
Published: November 2004

The analytic properties of the Gaussian hypergeometric function is reviewed and applied to the development of a Fortran function code. The code developed can be used to evaluate the hypergeometric function on the whole complex plane with arbitrary complex parametric values. In the process of numerically verifying the code, a trigonometric identity involving the hypergeometric function listed in most of the mathematical handbooks is found to be incorrectly stated.
FERMI SYSTEMS AND COMPUTER ALGEBRA
Authors: STEEB W.-H.
Published: November 2004

Computer algebra is a helpful tool in studying Fermi systems. We show how the anticommutation relations can be implemented with computer algebra. Then we give an application to the Hubbard model.
V CYCLE DYNAMICAL EXPONENT OF THE MULTI-SCALE-UPDATE ALGORITHM FOR THE 2-d XY MODEL
Authors: ADLER S. L. , BHANOT G. V.
Published: November 2004

We have computed the dynamical correlation exponent for the Multi Scale Algorithm recently proposed by us for the 2-d XY model. We find that z = 1.70 (2) in the high temperature phase and z = 1.60 (2) in the low temperature phase.
SCALING RESULTS FOR PARALLELISM ON THE INTEL i860 HYPERCUBE
Authors: JAKOBS A. , GERLING R. W.
Published: November 2004

A scaling theory for the parallel efficiency of simulations on MIMD computers is presented. It is successfully applied to the performance results recently reported by Kohring and Stauffer for different algorithms on an Intel i860 Hypercube. The discrepancies between the measured scaling exponents and our predictions are resolved within the framework of our general theory.
A LATTICE SOLID MODEL FOR THE NONLINEAR DYNAMICS OF EARTHQUAKES
Authors: MORA PETER , PLACE DAVID
Published: November 2004

A lattice solid model is presented that is capable of simulating the nonlinear dynamical processes (friction and fracture) associated with earthquakes. It is based on molecular dynamics principles to model interacting particles by numerically solving their equations of motion. Particles represent indivisible units of the system such as grains and interactions are described through effective potential functions. In this initial work, particles interact through radial pairwise potentials and the solid is made of particles arranged in a two–dimensional triangular lattice which corresponds to an isotropic elastic medium in the macroscopic limit. Simple and tractable potentials are specified to model brittle and ductile material. Numerical experiments of flawed brittle and ductile blocks subjected to uni–axial compression yield mode II fracturing behavior and characteristic stress–strain curves. In another experiment involving brittle blocks with rough surfaces being dragged past one another, stick–slip frictional behavior is observed. These results suggest that earthquakes can be simulated using the particle based modeling approaches even when the particles and their interactions are highly simplified.
MULTI-MILLION PARTICLE MOLECULAR DYNAMICS ON THE CM-5
Authors: LOMDAHL P. S. , BEAZLEY D. M. , TAMAYO P. , GRØNBECH-JENSEN N.
Published: November 2004

We outline a recently developed short-range molecular dynamics (MD) algorithm for message-passing MIMD computers. Timings and performance numbers are presented for a code, SPaSM, which implements the algorithm on the Connection Machine-5 (CM-5). We demonstrate that runs with more than 108 particles are now possible on massively parallel MIMD computers. The speed of the code scales linearly with the number of processors and with the number of particles and shows 95% parallel efficiency in the speedup. Recent results from 2D simulations of fracture dynamics are also presented
VECTORIZED AND PARALLELIZED ALGORITHMS FOR MULTI-MILLION PARTICLE MD-SIMULATION
Authors: FORM WOLFGANG , ITO NOBUYASU , KOHRING GREGORY A.
Published: November 2004

We present fully vectorized and parallelized algorithms for the molecular dynamics simulation of particle systems with short-range interaction. Speed of million particle updates per second are achieved with modern vector and parallel computers, thus making the simulation of million particle systems possible. We present results for the Cray YMP, JAERI/NEC MONTE-4 vector computers and the Intel Paragon XP/S and Thinking Machine CM-5 parallel computers.
SIMULATION OF SOUND PROPAGATION IN GRANULAR MEDIA ON THE CONNECTION MACHINE
Authors: MELIN STEPHAN
Published: November 2004

While experiments studying the sound propagation in granular media can only measure the behaviour of a few particles, it is possible to study the whole system at once with a computer simulation. In this article I will shortly present the simulation techniques which I use and a few results.
COMPUTATION OF THE SPATIAL STRING TENSION IN HIGH TEMPERATURE SU(2) GAUGE THEORY
Authors: BALI G. S. , SCHILLING K. , FINGBERG J. , HELLER U. M. , KARSCH F.
Published: November 2004

A detailed investigation of the temperature dependence of the spatial string tension σs in SU(2) gauge theory is presented. A sustained performance of 3 GFLOPS on a 64K Connection Machine CM-2 equivalent has been achieved. Scaling of σs between β = 2.5115 and β = 2.74, on large lattices, is demonstrated. Below the critical temperature, Tc, σs remains constant. For temperatures larger than 2Tc the temperature dependence can be parametrized by σs(T) = (0.369 ± 0.014)2g4(T)T2, where g(T) is a 2-loop running coupling constant with the scale parameter determined as ΛT = (0.076 ± 0.013)Tc.
QCD CALCULATIONS ON QCDPAX
Authors: KANAYA KAZUYUKI
Published: November 2004

The results of main QCD calculations performed on the dedicated parallel computer QCDPAX are reviewed. A project to construct a new parallel computer aiming at the peak performance of 300 GFLOPS is reported.
QCD ON THE MASSIVELY PARALLEL COMPUTER AP1000
Authors:   QCD-TARO Collaboration, invited talk, presented by I. O. Stamatescu and A. Nakamura, Akemi K. , Fujisaki M. , Okuda M. , Tago Y. , Hashimoto T. , Hioki S. , Miyamura O. , Takaishi T. , Nakamura A. , de Forcrand Ph. , Hege C. , Stamatescu I. O.
Published: November 2004

We present the QCD-TARO program of calculations which uses the parallel computer AP1000 of Fujitsu. We discuss the results on scaling, correlation times and hadronic spectrum, some aspects of the implementation and the future prospects.
APE100 AND BEYOND
Authors: TRIPICCIONE R.
Published: November 2004

This paper presents the basic elements of the APE100 architecture. It also describes the impact of APE100 machines on some areas of computational physics. Some ideas about possible evolutions of the APE100 architecture are finally discussed.
DISTRIBUTED DEADLOCK DETECTION ALGORITHMS
Authors: FLATEBO MITCHELL , DATTA AJOY KUMAR
Published: November 2004

A distributed system consists of a set of loosely connected state machines which do not share a global memory. The global state of the system depends on the state of each process in the system. The set of global states can be split up into two categories, legal and illegal. This paper deals with methods of detecting deadlocks in distributed systems. One way that has been used to detect deadlocks is by sending probes around the system. If a process thinks that it may be deadlocked, it initiates a probe. If the probe is received by the initiator, the initiator declares deadlock. This paper uses the idea of states of processes In order to detect the deadlock. The algorithm runs continually and does not have to be initiated. This paper presents deadlock detection algorithms for single and multiple outstanding requests. A method for deadlock resolution is also discussed. The algorithms detect all deadlocks and do not detect false deadlocks.
PERFORMANCE ESTIMATION OF LU FACTORISATION ON MESSAGE PASSING MULTIPROCESSORS
Authors: PURUSHOTHAM B. V. , BASU A. , KUMAR P. S. , PATNAIK L. M.
Published: November 2004

The paper proposes an analytical model for estimating the performance of Pipelined Ring algorithm for LU factorisation on any distributed memory message passing multiprocessor. Expressions for parallel execution time and speedup are derived from the computation-communication characteristics of the algorithm. Earlier methods on performance estimation of LU factorisation have been based on determining the number of floating point operations in the best and worst cases. The methodology proposed in this paper follows a different approach and estimates the performance of LU factorisation from a measurement of the execution time of the algorithm on a single processor and from a knowledge of the number of bytes communicated in different steps of the algorithm. The expression for parallel execution time of LU factorisation derived from the analytical model has been validated with experimental values obtained 011 a sixty-four transputer based multiprocessor. Results indicate that the methodology proposed in this paper can be used for estimating the execution time of Pipelined Ring algorithm for LU factorisation on any distributed memory message passing multiprocessor with high accuracy.
PERFORMANCE EVALUATION OF MULTICAST WORMHOLE ROUTING IN 2D-TORUS MULTICOMPUTERS
Authors: YANG C. S. , TSAI Y. M. , LIU C. Y.
Published: November 2004

Most recently, multicast communication has been included in multicomputer systems. Multicast communication refers to the delivery of the same message from a source node to an arbitrary number of destination nodes. The performance of multicomputers is highly dependent on the message routing scheme and the communication mechanism. Wormhole routing is the most promising switching technique used in the new generation multicomputers. In this paper, we propose a multicast wormhole routing algorithm for 2D-torus multicomputers. The multicast routing algorithm is based on a path-like routing scheme and offers deadlock-free routing. Our simulation which compared the 2D-mesh multicomputers shows that the multipath routing algorithm for 2D-torus multicomputers can reduce the communication traffic and the maximum distance in multicast communication.
SYSTOLIC GENERATION OF COMBINATIONS FROM ARBITRARY ELEMENTS
Authors: ELHAGE HASSAN , STOJMENOVIĆ IVAN
Published: November 2004

A systolic algorithm is described for generating, in lexicographically ascending order, all combinations of m objects chosen from an arbitrary set of n elements. The algorithm is designed to be executed on a linear array of m processors, each having constant size memory (except processor m, which has O(n) memory), and each being responsible for producing one element of a given combination. There is a constant delay per combination, leading to an O (C(m, n)) time solution, where C(m, n) is the total number of combinations. The algorithm is cost-optimal (assuming the time to output the combinations is counted), and does not deal with very large integers.
UNIMODULARITY AND THE PARALLELIZATION OF LOOPS
Authors: BARNETT MICHAEL , LENGAUER CHRISTIAN
Published: November 2004

The parallelization of loops can be made formal by basing it on an algebraic theory of loop transformations. In this theory, the concept of unimodularity arises. We discuss the pros and cons of insisting on unimodularity.
PARALLEL CONSTRUCTIONS OF HEAPS AND MIN-MAX HEAPS
Authors: CARLSSON SVANTE , CHEN JINGSEN
Published: November 2004

We study parallel solutions to the problem of implementing priority queues and priority deques. It is known that data structures for the implementation (e.g. the heap, the min-max heap, and the deap) can be constructed in linear sequential time. In this paper, we design optimal Θ(( log log n)2) time parallel algorithms with [Formula: see text] processors for the constructions in the parallel comparison tree model.
CHANNEL CLASSES: A NEW CONCEPT FOR DEADLOCK AVOIDANCE IN WORMHOLE NETWORKS
Authors: DUATO JOSÉ
Published: November 2004

In previous papers, we have developed the theoretical background for the design of deadlock-free adaptive routing algorithms for store-and-forward and wormhole networks. Some definitions and theorems have been proposed, developing conditions to verify that an adaptive algorithm is deadlock-free, even when there are cyclic dependencies between channels. Also, two design methodologies have been proposed.

In this paper, we propose a partial order between channels as well as an equivalence relation. This relation splits the set of channels into equivalence classes. Then, we extend our previous theory by considering equivalence classes (channel classes) instead of channels. This extension drastically simplifies the verification of deadlock freedom for adaptive routing algorithms with cyclic dependencies between channels. Finally, we present an example.
BROADCASTING TIME IN SPARSE NETWORKS WITH FAULTY TRANSMISSIONS
Authors: PELC ANDRZEJ
Published: November 2004

One node of a communication network holds a message which should reach all other nodes. In a unit of time a node can communicate with all neighbors but some transmissions may be faulty. In the model which assumes a bounded number of failures per time unit, all nodes must get the message for any location of faults, while for random independent failures the goal is to reach all nodes with high probability, for large networks. We establish relations between the number of links in networks and the time of fault-tolerant broadcasting.
PARALLEL BUDDY MEMORY MANAGEMENT
Authors: JOHNSON THEODORE , DAVIS TIMOTHY A.
Published: November 2004

Shared memory multiprocessor systems need efficient dynamic storage allocators, both for system purposes and to support parallel programs. Memory managers are often based on the buddy system, which provides fast allocation and release. Previous parallel buddy memory managers made no attempt to coordinate the allocation, splitting and release of blocks, and as a result needlessly fragment memory. We present a fast and simple parallel buddy memory manager that is also as space efficient as a serial buddy memory manager. We test our algorithms using memory allocation/deallocation traces collected from a parallel sparse matrix algorithm.
MATCHING POLYNOMIALS OF SERIES-PARALLEL GRAPHS
Authors: HSU LIH-HSING
Published: November 2004

We present an efficient algorithm for computing the matching polynomial of a series-parallel graph in O(n2) time. This algorithm improves on the previous result of O(n3). We also present a cost-optimal parallel algorithm for computing the matching polynomial of a series-parallel graph using an EREW PRAM computer with the number of processors p less than n2/ log n.
BIT-LEVEL SYSTOLIC ARRAYS FOR DIGITAL CONTOUR SMOOTHING BY ABEL-POISSON KERNEL
Authors: GLASA JÁN
Published: November 2004

Two different bit-level systolic arrays for digital contour smoothing by Abel-Poisson kernel which minimize the execution time and the number of functional elements required are suggested. The arrays are fully pipelined on the bit-level achieving very high clock frequency. They are implementable in VLSI and are dedicated for real-time applications.
SUB-LOGARITHMIC ALGORITHMS FOR THE LARGEST EMPTY RECTANGLE PROBLEM
Authors: OLARIU STEPHAN , SHEN WENHUI , WILSON LARRY
Published: November 2004

We show that the Largest Empty Rectangle problem can be solved by reducing it, in a natural way, to the All Nearest Smaller Values problem. We provide two classes of algorithms: the first one assumes that the input points are available sorted by x (resp. y) coordinate. Our algorithm corresponding to this case runs in O(log log n) time using [Formula: see text] processors in the Common-CRCW-PRAM model. For unsorted input, we present algorithms that run in [Formula: see text] time using [Formula: see text] processors in the Common-CRCW-PRAM, or in O( log n) time using [Formula: see text] processors in the EREW-PRAM model. No sub-logarithmic time parallel algorithms have been previously reported for this problem.
EFFICIENT PARALLEL ALGORITHMS FOR FINDING CHORDLESS CYCLES IN GRAPHS
Authors: CHANDRASEKHARAN N. , LAKSHMANAN V.S. , MEDIDI MURALIDHAR
Published: November 2004

We present simple and efficient parallel algorithms for obtaining a chordless cycle of length greater than or equal to k in a graph whenever such a cycle exists. Our results generalize and simplify existing results for detecting chordless cycles.
PERPETUAL GOSSIPING
Authors: LIESTMAN ARTHUR L. , RICHARDS DANA
Published: November 2004

In this paper, we introduce a new information dissemination problem in which gossiping is to occur continuously but with restricted use of the network. In this problem, information continues to be generated by each member of the network and, thus, the gossip process must be ongoing. However, in order to allow the network to be used for other purposes, the communications used by the gossip process are limited to k calls per time unit. We present some preliminary results on this new problem.