bluuebunny/crossref_metadata_2025 huggingface dataset:
On an alternative method for approximate solution of linear stochastic differential equations
Authors: Stahlberg J.
Published: July 2007

An approximate method for solving formal linear stochastic differential equations of first order is proposed. On the basis of the Reynold averaging technique, the stochastic differential equation is transformed into an infinite hierarchical system. This infinite system is cut off in such a manner that uncorrelated (totally randomly) and totally correlated stochastic processes are exactly included. By this the applicability of the Reynold method is extended.
On the total kinetic energy of our galaxy
Authors: Ninković S.
Published: July 2007

The total kinetic energy of the Galaxy is estimated from the potential energy by applying the virial theorem. The limits of the potential energy depend strongly on the value of the local escape velocity. They are estimated to be between −7. 1016 MȮ km2s−2 and −1. 1016 MȮ km2s−2 (escape velocity approximately between 450 km s−1 and 600 km s−1). The specific kinetic energy of the Galaxy as a whole is most likely about 21 000 km2s−2, being equally distributed among the subsystems if the local escape velocity is near its lower limit; the higher the local escape velocity is, the higher is the specific kinetic energy of the Galaxy due to the influence of the dark corona. The specific kinetic energy of the dark corona tends to become equal to that of the Galaxy as a whole for very high values of the local escape velocity. For the purpose of estimating the totl potential energy of the Galaxy, inter alia, a new model of the Milky Way is developed, which yields both the potential and the density analytically so that it is suitale for calculating the galactocentric orbits.
A new suspected apsidal period for HS Herculis
Authors: Todoran I.
Published: July 2007

From a preliminary analysis of observed minima of the eclipsing binary HS Herculis, a new apsidal period is postulated. A general possible error in Oapsidal period is emphasized.
Nearby galaxies. I. The catalogue
Authors: Schmidt K.‐H. , Boller T.
Published: July 2007

The data of 289 nearby galaxies have been compiled. The inclusion of a galaxy into the catalogue depends on its redshift as in the catalogue of Kraan‐Korteweg and Tammann (1979) (vLG = 500 kms−1) or on the fact that the objects are known to be certain or probable members of nearby groups. The galaxies in the sample form the Local Group with 51 certain und probable members and several additional groups. One third of the galaxies in the catalogue (96 objects) does not seem to belong to any group.

The main emphasis is to get a distance‐limited sample of galaxies, especially of dwarf objects. It is intended to discuss the properties of the sample in a following part of the investigation.
Orbits in an anisotropic radiation field
Authors: Mioc V. , Radu E.
Published: July 2007

The elliptic‐type motion around a source whose luminosity is anisotropic is being perturbatively treated. Using a Fourier expansion for the perturbing force, exact expressions describing the evolution of each orbital element are determined from Newton‐Euler equations. For near‐unit frequency the resonant solutions are pointed out. An approximate expression for the variation of the nodal period is determined, too. The behaviour of the radius vector of the unstable orbit (resonance case) is pointed out, showing periodic variations of constantly increasing amplitude. The (both angular and physical) time scale for escape is estimated. Concrete astronomical situations modellable in this way are mentioned.
Star complexes and a scenario for the evolution of spiral galaxies
Authors: Chernin A. D. , Efremov Yu. N.
Published: July 2007

The major features of star complexes as “building blocks” of the large‐scale structure of spiral galaxies are presented and a scenario for spiral formation is suggested on this basis.
Limb darkening effect included in a simple formula for solar energy flux
Authors: Badescu V.
Published: July 2007

It is proposed a formula for the solar energy flux including the limb darkening effect and beeing valid at any distance from the Sun.
Minor planet observations 1984‐1990
Authors: Fogh Olsen H. J.
Published: July 2007

An overview of the minor planet search performed in the period 1984–1990 at Brorfelde Observatory is presented. All basic information about the observations is given but the positions are not presented because they are already published in Minor Planet Circulars. 1973 positions have been measured on 413 plates. 303 positions belong to unknown minor planets. At the end of 1992, 42 of these are numbered, having got enough observations to calculate a reliable orbit.
Variations of the solid Earth's center of mass due to oceanic tides
Authors: Brosche P. , Wünsch J.
Published: July 2007

Periodic variations in the location of the center of mass of the solid Earth due to ocean tides are derived from the ocean tide model of Seiler (1991). The sum of nine partial tides leads to changes in the coordinates X, Y, Z within a range of 1cm.
Rapid oscillations of five stars in the spectral range G and K. II
Authors: Hildebrandt G.
Published: July 2007

The five stars HD 11112, HD 170747, HD 186651, HD 205390 and HD 224834 are a second group of objects enclosed in a larger observational programme for the search of rapid oscillations. They have been observed with the 50 cm photoelectrical ESO telescope at La Silla (Chile). For the star HD 205390 a variation of 163.8 min was found. The two objects HD 11112 and HD 186651 are suspected to be variable with periods of 139 min and 142.2 min and its overtones, respectively. But a verification of these results is necessary. For the last two objects HD 170747 and HD 224834 no variations were detected.
Nearby galaxies. Revised machine–readable version of the catalogue
Authors: Schmidt K. H. , Priebe A. , Boller T.
Published: July 2007

A short description of the new (machine‐readable) version of the catalogue of nearby galaxies published earlier by Schmidt and Boller (1992) is given.
Expanding, homogeneous, ellipsoidal density perturbations. III. A simple theory for the acquisition of angular momentum by tidal torques with the effects of the spin growth on the expansion included
Authors: Caimmi R.
Published: July 2007

The effects of the acquisition of angular momentum on the expansion of homogeneous, ellipsoidal density perturbations is investigated by generalizing the theory of previous papers of this series, where spin grows to the first order in overdensity. A small difference is found to be between the two cases, except for the fact that the body under consideration becomes unbound earlier in the current approach. A comparison is also made with the results of a different theory, where spin grows to the second order in overdensity. Quasi‐oblate triaxial configurations turn out to gain less angular momentum in respect to both oblate and more elongated configurations with same minor to major axis ratio. In all cases of physical interest, the spin growth from the beginning to the maximum ellipsoidal volume exceeds the spin growth from the maximum ellipsoidal volume to the turnaround of the major axis, by a factor of at least 3. It is also inferred that the spin growth from the turnaround of the major axis on, probably does not exceed about one third the angular momentum previously gained.
The pole of (51) Nemausa
Authors: Kristensen L. Kahl
Published: July 2007

The complex lightcurves make (51) Nemausa a good case for the study of general methods for pole determination. From six lightcurves the pole is determined to 20h24m; +53° (1950); the rotation is retrograde with period 7h.782936 ± 0h.000005. Presence of nongeometric scattering is proved by a significant 0.008 mag amplitude. Formulae and photometric elements are given for predictions of the shapes of lightcurves in future oppositions. The precision of the Fourier coefficients may be reduced below the present ±0.003 mag level by avoiding the systematic errors in the observations due to phase factor variations and discontinuities when changing comparison stars.
Compact objects with large masses
Authors: Verozub L. V.
Published: July 2007

It is shown that gravitational theory allows stable equilibrium configurations of the degenerated Fermi gas, whose masses M ≫ M⊙ and sizes are less than α = 2GM/c. They have no events horizon at the distance r = α from the center. Orbits of test particles near the above objects are considered.
Kasner‐like, inflationary and steady‐state solutions in multi‐dimensional cosmology
Authors: Bleyer U. , Zhuk A.
Published: July 2007

Multi‐dimensional cosmological models with n(n > 1) Ricci‐flat spaces and a scalar field are discussed classically and with respect to canonical quantization. These models are integrable. Two classes of solutions are obtained. One class of solutions generalizes the Kasner solutions. For special additional conditions we find another solution describing extended inflation connected with a constant volume of the whole multidimensional space (steady‐state).
Oceanic and solid Earth angular momentum
Authors: Brosche P. , Seiler U.
Published: July 2007

We reconsider two hypotheses used in calculating the transfer of angular momentum between the oceans and the solid Earth: (1) The locked‐cean‐ypothesis was already given up some time ago; here we provide a simple manner of understanding the relative importance of the motion and matter term. (2) The isolation hypothesis implied the isolation of the whole Earth in short timescales with regard to angular momentum exchange, and consequently, the neglection of the exchange with the tide‐enerating body. It is shown that for present accuracy requirements this exchange has to be taken into account.
Catalogue of Shakhbazian compact groups of galaxies. V.
Authors: Stoll D. , Tiersch H. , Braun M.
Published: July 2007

We present the position and references (if available) of all the galaxies of the Shakhbazian survey being the largest survey of compact galaxy groups. For the estimation of the coordinates the Digitized Sky Survey was used. This paper contains the data of 48 Shakhbazian groups north of δ > + 2deg;30' (Shkh 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 22, 23, 25, 26, 28, 29, 31, 34, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56).
Dark matter, galaxy sizes and exponential potential
Authors: Capaccioli M. , Longo G. , Capozziello S. , De Ritis R.
Published: July 2007

Starting from the standard Newtonian theory, we derive in the propagation equation of perturbations an effectively Yukawalike potential invoked by several authors as an alternative to dark matter. This approach provides with a simple explanation of the segregation observed for dynamically ‘hot’ systems in the plane defined by their effective parameters.
Spectral survey of the Comet Halley atmosphere during an occultation of a star
Authors: Nazarchukd̊ H. K. , Shulman L. M.
Published: July 2007

On November 15, 1985 a star was occulted by Comet Halley. Seven consequent spectra of the star has been obtained with 5‐minute exposition with the TV scanner at 6‐meter telescope. Simultaneously seven spectra of the cometary atmosphere were obtained at the projected distance 40” from the star. A method is developed to calculate the optical thickness of the cometary atmosphere as a function of wave length and the nucleocentric distance. This function is given in the spectral range 3925 Å−4850 Å.
Possible relations between the rotational axis of the Earth's inner core and the magnetic dipole axis
Authors: Greiner‐Mai H.
Published: July 2007

The geomagnetic field is maintained by amagnetohydrodynamic dynamo process within the liquid outer core. The distribution of the associated electric currents is modified if the outer core is bounded by electrically conducting material. Then, eddy currents and the related magnetic fields are generated within these regions. In particular, the relative rigid rotation of the inner core produces a secondary magnetic field, which is superimposed on the dynamo field. The angle between the dipole axis of the total field and the rotational axis of the inner core is an important quantity needed for the theory of polar motion of the Earth. This angle is investigated for a broad spectrum of angular velocities of the inner core.

To simplify the mathematical procedure, we model the dynamo field using an axisymmetric field generated by a system of electric currents within the outer core. The conductivity of the mantle is neglected. We find that the position of the dipole axis depends on the angular velocity of the inner core as well as on the distribution of the current system within the outer core. Coincidence of both axes can be reached if the angular velocity is high enough and if the current system is concentrated within a thin sheet near the outer core‐inner core boundary.
Dynamical bispherical separability and physical realizability
Authors: Stewart P.
Published: July 2007

The Stäckel form of potential required for separability of the equations of motion is examined in relation to Poisson's equation for a finite mass gravitational system whose mass is spatially concentrated with a density which is everwhere finite.
A survey of main‐belt asteroids I. Positions and improved orbital elements for 75 numbered asteroids.
Authors: Lagerkvist C.‐I. , Hahn G. , Lundström M. , Lagerros J. S. V. , Hernius O. , Tancredi G.
Published: July 2007

More than 7000 positions of moving objects have been detected on 33 films obtained with the Schmidt telescope at the European Southern Observatory in Chile during August and September 1995. The majority of these asteroids are previously unobserved. This paper presents the astrometric methods as well as the magnitude determinations. The derived positions for the numbered asteroids are presented and for these improved orbital elements have been calculated using all available positions.
Predicted star counts and mean parallaxes down to the 23rd magnitude
Authors: Kharchenko N. , Rybka S. , Yatsenko A. , Schilbach E.
Published: July 2007

Star counts and mean parallaxes as a function of B, V, R magnitudes down to 23 are presented. The data were computed by the use of two fundamental equations of stellar statistics. The assumed model considers the Galaxy as a symmetrical system with respect to its rotation axis and to its equatorial plane and as composed of the thin disk (main sequence and red giants), the thick disk and spheroid populations.

Numbers of stars and mean parallaxes were derived in bins of galactic longitude and latitude of 30° and 10°, respectively. For the computation of the mean parallaxes depending on Galactic coordinates and magnitudes, series of products of Hermite and Legendre polynomials and of Fourier terms were used.

The results of this paper may help in the planning of future survey missions and in the design of new telescopes. In addition, mean parallaxes can be used to derive corrections to absolute parallaxes and proper motions for any position in the sky.
The influence of turbulence on the solar p‐mode frequencies I. Free‐mode approximation
Authors: Rüdiger G. , Hasler K.‐H. , Kitchatinov L. L.
Published: July 2007

The influence of turbulence on the frequencies of free acoustic modes in convection zones is considered. The frequencies are modified via the speed of sound by the turbulence‐induced alterations of the effective pressure: (i) by the correlated fluctuations of temperature and density and (ii) the pressure part of the Reynolds stress. The two effects shift the frequency of low l p‐modes in opposite directions. In addition, the correlation of the density fluctuations with the random velocity — the eddy‐mass flow — is also relevant. It is, in a steady state, balanced by a vertical mean velocity. The balance results in a rather small net effect completely disappearing for highly nonradial oscillations. Both effects of the density fluctuations produce a redshift of the low l p‐mode frequencies. The Reynolds stress, however, makes a blueshift of the frequencies relative to that computed for a laminar gas. This effect dominates for subsonic turbulences. The applied second‐order correlation‐approximation, however, only holds for the lowest frequencies, where the KORONAS (solar minimum) data are indicating a blueshift. Of particular importance for the present concept is the expected cycle‐variations of the lineshifts, i.e. the consideration of the magnetic modification of the various contributions. Observations may show whether the suggested modifications of the solar oscillation theory are correct.
Far infrared study of AGNs: a status report
Authors: Assendorp R.
Published: July 2007

We have initiated a new study into the Far Infrared properties of Active Galaxies. We use several samples of AGNs and try to get as clean IRAS fluxes as possible by inspecting the raw IRAS data. Using high resolution images enables us to resolve galaxies that are confused in the IRAS Point Source Catalogue and IRAS Faint Source Survey.
The knotty structure of the HII dwarf galaxy F348
Authors: Rafanelli P. , Roi S. , Tegon A. , Schulz H. , Di Serego‐Alighieri S. , Komossa S. , Richter G. , Vennik J.
Published: July 2007

[OIII] images and blue spectra of the emission‐line dwarf galaxy F348 are presented. In [OIII] light, the object contains two knots about 9” NE of the nucleus and one large extended knot 11” to the SW. The nuclear region is hundred times less luminous in emission‐line light than the knots. Despite the presence of line intensity ratios [OIII]λ5007/Hβ > 3 the prior classification as a Seyfert‐2 object cannot be upheld. This clinches an earlier suggestion by Veron‐Cetty & Veron (1986). In particular, we show that the line spectra can be modeled with photoionization models employing stellar input continua. Also, the line luminosities of the extranuclear knots are typical for giant HII regions. There is neither evidence for tidal tails nor for high velocity differences between the knots. In addition, the linear arrangement of the knots does not support interaction. It rather suggests self‐propagating star formation In this picture, the faintness of the nuclear region can be understood by an edge‐on view. In addition, the nuclear starburst appears to be fading in contrast to the young extranuclear star formation regions. Within the scheme of Melnick (1987), F348 has to be classified as a multiple‐system HII galaxy.
The Hipparcos distances of open clusters and their implication on the local variations of the ΔY/ΔZ ratio
Authors: Efremov Yu. N. , Schilbach E. , Zinnecker H.
Published: July 2007

Arguments are collected to demonstrate that recent Hipparcos results on the distances of open clusters are in agreement with previous estimates in the Russian literature which have pointed to a shorter distance scale. Evidence of the absence of a universal correaltion between Helium and metal abundances is given. It is suggested that violations of this correlation may explain the apparent contradictions between the relative positions of the main sequences of open clusters found from the Hipparcos distances.
The G‐dwarf problem in the solar neighbourhood: a Lagrangian picture
Authors: Caimmi R.
Published: July 2007

Recent data on the empirical metallicity distribution of G dwarfs in the disk solar neighbourhood are fitted in two different ways. We use an extended Poisson distribution in the limit where the probability of star formation is small, and a Gauss distribution in the limit where a large number of physical variables is required to determine stellar metal abundance. Both are found to reproduce the data at the same (acceptable) extent, with a slight preference for the former. The emprirical, differential metallicity distribution of G dwarfs in the disk solar neighbourhood is compared with its theoretical counterpart, in the picture of a closed, comoving model of chemical evolution. The limits of the currently used infall models are discussed and a scenario of galactic formation and evolution is presented. The Galactic history is thought as made of two main phases: contraction (which produces the extended component) and equilibrium (which gives the disk). In this view, the stars observed within the solar cylinder did not necessarily arise from the primordial gas which later collapsed into the disk solar neighbourhood. It is found that the G‐dwarf problem is strongly alleviated, with the possible exception of the low‐metallicity and high‐metallicity tail of the distribution. The best choice of parameters implies: (i) a metal yield in the contraction phase which is larger by a factor of about 5 with respect to the equilibrium phase; (ii) a model halo mass fraction of about 0.3; (iii) a model disk mass fraction of about 0.6. It provides additional support to the idea of a generalized Schmidt star formation law, which is different in different phases of evolution. The model, cumulative, G‐dwarf metallicity distribution in the disk solar neighbourhood is found to predict too may low‐metallicity stars with respect to its empirical counterpart, related to a Poissonian or Gaussian fit. The main resons for the occurrence of a G‐dwarf problem are discussed. Finally, a stochastic process of star formation, related to a Poisson distribution, is briefly outlined.
The REX survey: a search for BL Lac objects
Authors: Maccacaro T. , Caccianiga A. , Della Ceca R. , Wolter A. , Gioia I. M.
Published: July 2007

We present the scientific goals and the strategy of the REX survey, a project which has been recently initiated at the Brera Astronomical Observatory in Milan with the aim of selecting a large and statistically representative sample of BL Lac objects and other kinds of Radio Loud Active Galactic Nuclei. More than 1200 PSPC images (for a total of about 2700 square deg. of sky) have been searched for sources detected also in the VLA NVSS survey (as of June 1977). The data and source selection criteria, the cross‐correlation technique and preliminary results are presented and discussed.
The extragalactic X‐ray background at 0.25 keV
Authors: Warwick R. S. , Roberts T. P.
Published: July 2007

We review recent results from shadowing experiments relating to the intensity of the extragalactic X‐ray background at 0.25 keV. The measurements appear to be converging on a value in the range 20 → 35 keV cm−2 s−1 keV−1. The implication is that over 80% of the background signal at 0.25 keV may have been resolved into discrete sources in the deepest pointed observations carried out by ROSAT.
Recent results from the SHARC Survey
Authors: Romer A. K. , Nichol R. C. , Collins C. A. , Burke D. J. , Holden B. P. , Ulmer M. P. , Pildis R. A. , Metevier A.
Published: July 2007

We review recent results from the SHARC Survey for distant X‐ray clusters of galaxies. We first discuss the SHARC South project which finds no evidence for evolution in the faint end of the X‐ray cluster luminosity function out to a redshift of z ≲ 0.7. We then give an overview of the Bright SHARC project; this project will provide an independent measurement of the evolution of bright (Lx[0.5 ‐ 2keV] > 3 × 1044 erg s−1) X‐ray clusters and allow us to put strong constraints on the value of ω0.
ROSAT HRI Survey of the Large Magellanic Cloud
Authors: Chu You‐Hua , Snowden S. L.
Published: July 2007

We have started a ROSAT HRI survey of the Large Magellanic Cloud (LMC). The current scope of the survey is to map the 30 Doradus region and the bar of the LMC with at least 20 ksec exposure at each position. The survey grid has a 15′ separation between adjacent pointings. The survey has been awarded a total of 39 priority B pointings in AO5–7. The HRI survey of the LMC will provide X‐ray luminosity functions of point sources complete down to ∽ 1 × 1034 erg s−1. In addition, the survey images have resolved small diffuse sources, such as the SNR 0534–69.9 and the superbubble 30 Dor C, and detected diffuse emission on large scales. An HRI mosaic of the LMC is presented and compared to an Hα image.
WFXT: a wide field X‐ray optics
Authors: Chincarini G. , Citterio O. , Conconi P. , Ghigo M. , Mazzoleni F.
Published: July 2007

We describe the main characteristics of a small satellite mission aimed to survey part of the sky in the x‐ray band (WAXS — Wide Angle x‐ray Survey) using a Wide Field of view X‐ray Telescope (WFXT). We demonstrate that using the new technologies we have developed, it is possible to construct x‐ray mirrors according to a new optical design which optimize the angular resolution over a large field of view.
Ba II lines as luminosity indicators: s‐Cepheids and non‐variable supergiants
Authors: Andrievsky S. M.
Published: July 2007

Ba II line equivalent widths appear to be well correlated with the absolute magnitudes for yellow supergiants. Two Ba II lines 5853.6 Å and 6141.7 Å were applied for investigation of the possible relation between their equivalent widths and Mv for small‐amplitude Cepheids and non‐variable supergiants.
Numerical simulations of the magnetic field distribution in a solar complex of activity
Authors: Tikhomolov E. M.
Published: July 2007

Powerful solar complexes of activity are supposed to result from the excitation of Rossby vortices within a thin layer beneath the convection zone. Numerical simulations demonstrate that Rossby vortices generate large‐scale arc‐like magnetic structures. It is shown that the most powerful complex of activity observed in June‐July 1982 was likely to be a result of the excitation of a Rossby anticyclone rather than a cyclone.
Observations of distant solar system bodies
Authors: Magnusson P. , Lagerkvist C.‐I. , Lagerros J. S. V. , Dahlgren M. , Lundsrtöm M.
Published: July 2007

Multicolour VRI photometry and astrometry of one Centaur and seven Edgeworth‐Kuiper objects were obtained. One object, 1994 JQ1 may be as red as 5145 Pholus, the reddest minor planet previously known. The Centaur 1995 DW2 has more moderate colour indices, similar to main‐belt asteroids. Seven R‐magnitudes were obtained for 1994 JS, 1995 FB21, and 1995 GY7. No light variation above the expected noise is evident, apart from a few outliers. A total of 47 astrometric positions were obtained for the eight objects. The four nights of observations with the ESO New Technology Telescope covered 0.52 square degrees. Two previosuly unknown object, 1995 FB21 and 1995 GY7, were discovered. We estimate the density of Edgeworth‐Kuiper objects brighter than R = 24 to 5.3 per square degree of sky near the ecliptic.
Application of metabolic flux analysis to identify the mechanisms of free fatty acid toxicity to human hepatoma cell line
Authors: Srivastava Shireesh , Chan Christina
Published: July 2007

Chronic exposure to elevated levels of free fatty acids (FFAs) has been shown to cause cell death (lipotoxicity), but the underlying mechanisms of lipotoxicity in hepatocytes remain unclear. We have previously shown that the saturated FFAs cause much greater toxicity to human hepatoma cells (HepG2) than the unsaturated ones (Srivastava and Chan, 2007). In this study, metabolic flux analysis (MFA) was applied to identify the metabolic changes associated with the cytotoxicity of saturated FFA. Measurements of the fluxes revealed that the saturated FFA, palmitate, was oxidized to a greater extent than the non‐toxic oleate and had comparatively less triglyceride synthesis and reduced cystine uptake. Although fatty acid oxidation had a high positive correlation to the cytotoxicity, inhibitor experiments indicated that the cytotoxicity was not due to the higher fatty acid oxidation. Application of MFA revealed that cells exposed to palmitate also had a consistently reduced flux of glutathione (GSH) synthesis but greater de novo ceramide synthesis. These predictions were experimentally confirmed. In silico sensitivity analyses identified that the GSH synthesis was limited by the uptake of cysteine. Western blot analyses revealed that the levels of the cystine transporter xCT, but not that of the GSH‐synthesis enzyme glutamyl‐cysteine synthase (GCS), were reduced in the palmitate cultures, suggesting the limitation of cysteine import as the cause of the reduced GSH synthesis. Finally, supplementing with N‐acetylL‐cysteine (NAC), a cysteine‐provider whose uptake does not depend on xCT levels, reduced the FFA‐toxicity significantly. Thus, the metabolic alterations that contributed to the toxicity and suggested treatments to reduce the toxicity were identified, which were experimentally validated. Biotechnol. Bioeng. 2008;99: 399–410. © 2007 Wiley Periodicals, Inc.
Quartz: an autonomous navigation system for MOUT simulations
Authors: Ting Shang‐Ping , Zhou Suiping
Published: July 2007

Autonomous navigation systems are important to Military Operations on Urbanized Terrain (MOUT) simulations for generating realistic tactical behaviours for the non‐player characters (or bots). In this paper, we describe our work on Quartz, an autonomous navigation system for MOUT simulations. Novel features of Quartz include qualitative spatial representation and hierarchical spatial reasoning which enables fast situation analysis and human‐like path planning in a dynamic environment. To assess the effectiveness of Quartz, we have integrated it into Twilight City, a virtual environment for MOUT simulations. Experimental results show that Quartz is very effective for quick tactical path generation in dynamic MOUT environments. Copyright © 2007 John Wiley & Sons, Ltd.
Bar‐net driven skinning for character animation
Authors: Zhang Jian J. , Yang Xiaosong , Zhao Yunfeng
Published: July 2007

In this paper we present a physically motivated technique for the deformation of animated characters, called thebar‐net driven skinning. We use a bar‐network (bar‐net) as a deforming mechanism. This technique can be used similarly to a conventional skinning tool, but can also make a skin surface behave in a physically plausible manner due to the inherent physical properties of the network. A bar‐net is a structure commonly used in structural engineering. Its shape depends on the structural and material properties and the forces acting upon it. Computing the rest shape of an arbitrary bar‐net is a time‐consuming non‐linear problem. In order to speed up the computation and also for such a bar‐net to be used intuitively to help computer animation, we have defined a set of properties that a desirable bar‐net should satisfy. This allows a bar‐net shape finding problem to be solved using linear equations. We adopt a two‐layer structure for the representation of a skin surface, including a coarse mesh and a fine mesh. To deform a skin surface, we couple a bar‐net to its coarse mesh, which in turn deforms the fine mesh when the coupled bar‐net is deformed. The fine surface mesh can be of different forms, including Nurbs, subdivision surfaces and polygons. Copyright © 2007 John Wiley & Sons, Ltd.
Dynamics and Counterion‐Dependence of the Structures of Weakly Bound Ag+–P4S3 Complexes
Authors: Raabe Ines , Antonijevic Sasa , Krossing Ingo
Published: July 2007

In an earlier publication (J. Am. Chem. Soc. 2002, 124, 7111) we showed that polymeric cationic [Ag(P4S3)n]+ complexes (n=1, 2) are accessible if partnered with a suitable weakly coordinating counterion of the type [Al(ORF)4]− (ORF: poly‐ or perfluorinated alkoxide). The present work addresses the following questions that could not be answered in the initial report: How many P4S3 cages can be bound to a Ag+ ion? Why are these complexes completely dynamic in solution in the 31P NMR experiments? Can these dynamics be frozen out in a low‐temperature 31P MAS NMR experiment? What are the principal binding sites of the P4S3 cage towards the Ag+ ion? What are likely other isomers on the [Ag(P4S3)n]+ potential energy surface? Counterion influence: Reactions of P4S3 with Ag[Al{OC(CH3)(CF3)2}4] (Ag[hftb]) and Ag[{(CF3)3CO}3Al‐F‐Al{OC(CF3)3)}3] (Ag[al‐f‐al]) gave [(P4S3)Ag[hftb]]∞ (7) as a molecular species, whereas [Ag2(P4S3)6]2+[al‐f‐al]−2 (8) is an isolated 2:1 salt. We suggest that a maximum of three P4S3 cages may be bound on average to an Ag+ ion. Only isolated dimeric dications are formed with the largest cation, but polymeric species are obtained with all other smaller aluminates. Thermodynamic Born–Haber cycles, DFT calculations, as well as solution NMR and ESI mass spectrometry indicate that 8 exhibits an equilibrium between the dication [Ag2(P4S3)6]2+ (in the solid state) and two [Ag(P4S3)3]+ monocations (in the gas phase and in solution). Dynamics: 31P MAS NMR spectroscopy showed these solid adducts to be highly dynamic, to an extent that the 2JP,P coupling within the cages could be resolved (J‐res experiment). This is supported by DFT calculations, which show that the extended PES of [Ag(P4S3)n]+ (n=1–3) and [Ag2(P4S3)2]+ is very flat. The structures of α‐ and γ‐P4S3 were redetermined. Their variable‐temperature 31P MAS NMR spectra are discussed jointly with those of all four currently known [Ag(P4S3)n]+ adducts with n=1, 2, and 3.
Electron Transfer to Sulfides and Disulfides: Intrinsic Barriers and Relationship between Heterogeneous and Homogeneous Electron‐Transfer Kinetics
Authors: Meneses Ana Belèn , Antonello Sabrina , Arévalo Maria Carmen , González Concepcion Carmen , Sharma Jadab , Wallette Andrea N. , Workentin Mark S. , Maran Flavio
Published: July 2007

The electron‐acceptor properties of series of related sulfides and disulfides were investigated in N,N‐dimethylformamide with homogeneous (redox catalysis) and/or heterogeneous (cyclic voltammetry and convolution analysis) electrochemical techniques. The electron‐transfer rate constants were determined as a function of the reaction free energy and the corresponding intrinsic barriers were determined. The dependence of relevant thermodynamic and kinetic parameters on substituents was assessed. The kinetic data were also analyzed in relation to corresponding data pertaining to reduction of diaryl disulfides. All investigated reductions take place by stepwise dissociative electron transfer (DET) which causes cleavage of the CalkylS or SS bond. A generalized picture of how the intrinsic electron‐transfer barrier depends on molecular features, ring substituents, and the presence of spacers between the frangible bond and aromatic groups was established. The reduction mechanism was found to undergo a progressive (and now predictable) transition between common stepwise DET and DET proceeding through formation of loose radical anions. The intrinsic barriers were compared with available results for ET to several classes of dissociative‐ and nondissociative‐type acceptors, and this led to verification that the heterogeneous and the homogeneous data correlate as predicted by the Hush theory.
Synthesis and Charge/Discharge Properties of Polyacetylenes Carrying 2,2,6,6‐Tetramethyl‐1‐piperidinoxy Radicals
Authors: Qu Jinqing , Katsumata Toru , Satoh Masaharu , Wada Jun , Igarashi Jun , Mizoguchi Kenji , Masuda Toshio
Published: July 2007

The 2,2,6,6‐tetramethyl‐1‐piperidinoxy (TEMPO)‐containing acetylenic monomers HCCC6H3‐p,m‐(CONH‐4‐TEMPO)2 (1), HCCC6H3‐p,m‐(COO‐4‐TEMPO)2 (2), (S,S,S,S)‐HCCC6H3‐p,m‐[CO‐NHCH{COO‐(4‐TEMPO)}CH2COO‐(4‐TEMPO)]2 (3), (S,S)‐HCCC6H4CO‐NHCH{COO‐(4‐TEMPO)}CH2COO‐(4‐TEMPO) (4), HCCC6H4‐p‐OCO‐4‐TEMPO (5), HCCCH2C(CH3)(CH2OCO‐4‐TEMPO)2 (6), HCCCH2NHCO‐4‐TEMPO (7), and HCCCH2OCO‐4‐TEMPO (8) were polymerized to afford novel polymers containing the TEMPO radical at high densities. Monomers 1, 3–6, and 8 provided polymers with average molecular weights of 10 000–136 500 in 62–99 % yield in the presence of a rhodium catalyst, whereas monomers 2 and 7 gave insoluble polymers in 100 % yield. The formed polymers were thermally stable up to approximately 274 °C according to thermogravimetric analysis (TGA). All the TEMPO‐containing polymers demonstrated reversible charge/discharge processes, whose discharge capacities were 21.3–108 A h kg−1. In particular, the capacity of poly(1)‐, poly(4)‐, and poly(5)‐based cells reached 108, 96.3, and 89.3 A h kg−1, respectively, which practically coincided with their theoretical values.
Determination of nucleation kinetics of potassium tetraborate tetrahydrate
Authors: Sahin O. , Dolas H. , Demir H.
Published: July 2007

In this study, the metastable zone width of potassium tetraborate tetrahydrate was determined for four different temperatures and cooling rates. The induction period of potassium tetraborate tetrahydrate in aqueous solution was examined according to polythermal method by using visual observation. The induction period, which changes inversely proportional to the nucleation rate has been used to determine the interfacial tension between the potassium tetraborate tetrahydrate and aqueous solution. By using interfacial tension, the nucleation parameters such as Gibbs free energy change for the formation of critical nucleus, ΔG*, free energy of formation, ΔG, radius of critical nucleus, r and number of molecules in the critical nucleus, i* has been calculated. The effect of Li+ and Ca2+ impurities on metastable zone width has been studied. The metastable zone width of aqueous solution of potassium tetraborate tetrahydrate decreases with increasing impurity concentrations. The equilibrium saturation concentration change is high in the presence of Ca2+ ions while it is low in the presence of Li+ ions. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigations on nucleation kinetics, growth and characterization of sulphanilic acid single crystals
Authors: Mythili P. , Kanagasekaran T. , Gopalakrishnan R.
Published: July 2007

Nucleation parameters such as radius of critical nucleus, critical free energy change and interfacial tension were evaluated for Sulphanilic acid (SAA) single crystals. Metastable zone width and induction period values were determined to optimize the growth parameters. The interfacial tension values estimated using the experimentally determined induction period is found to be comparable with theoretical values. SAA crystals were grown with the optimized growth parameters. The formation of SAA crystals was confirmed by powder X‐ray diffraction and FT‐IR studies. The density measurements were carried out by both theoretical and experimental methods. The NLO behaviour of SAA crystals was tested by Kurtz‐ Perry technique. The mechanical hardness was studied by Vickers Microhardness tester. The UV‐Vis spectral analysis was carried out on the SAA crystals to study the optical properties. The laser damage threshold values of the SAA crystals are found to be 7.6 and 6.6 GW/cm2 for single and multiple shots, respectively. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of solvent and crystallization method on the crystal habit of metronidazole
Authors: Di Martino P. , Censi R. , Malaj L. , Capsoni D. , Massarotti V. , Martelli S.
Published: July 2007

In the present study, metronidazole was crystallized in several solvents, according to both the “cooling crystallization” and the “crystallization by non‐solvent addition”. Particle properties, such as crystal habit, elongation ratio, and mean particle size, were determined by SEM analysis. Structural changes and development of polymorphic forms were excluded by both Differential Scanning Calorimetry (DSC) and X‐Ray Powder Diffractometry (XRPD). Crystal habit (and thus elongation ratio) was typically influenced by both the solvent polarity index and the crystallization method: solvents with higher polarity index tended to promote acicular or stick‐shaped crystals with a high elongation ratio, while isodimensional crystals were promoted by decreasing the polarity index, as was particle aggregation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conflict, identity, and resilience: Negotiating collective identities within the Israeli and Palestinian diasporas
Authors: Coleman Peter T. , Lowe J. Krister
Published: July 2007

Collective identities serve many important psychological and practical functions in group life, but under conditions of protracted conflict, such identities can become a primary obstacle to peace. This article presents a program of exploratory research and model‐building on collective identity negotiation with members of the Palestinian and Israeli diasporas during a high‐intensity phase of the conflict..
Environmental conflict resolution: Relational and environmental attentiveness as measures of success
Authors: Foley Tony
Published: July 2007

When evaluating the success of environmental conflict resolution (ECR), the use of traditional measures of success, such as agreementcounting and participant satisfaction surveys, provide an incomplete picture. This article proposes two measures to evaluate ECR in terms of both process and outcome: Is the process transformative of the participants? Is the process designed to be attentive to environmental outcomes?
Schall im Niederdruckplasma
Authors: Wojaczek Karl
Published: July 2007

Bei der lokalen Beeinflussung einer Xenon‐Niederdruckentladung mittels einer impulsbetriebenen Hilfsentladung wurde auf photoelektrischem Wege eine sich in die positive Säule hinein ausbreitende Störung beobachtet, welche als Neutralgasschall gedeutet wird. Für die genannte. Deutung spricht die Größe der Ausbreitungsgeschwindigkeit sowie deren Unabhängigkeit von Stromrichtung, Frequenz und Gasdruck. Die Schallerzeugung kommt hauptsächlich durch die impulsförmig erfolgende Aufheizung des Neutralgases im Bereich der Hilfsentladung zustande. An der schallbedingten Modulation des von der Entladung emittierten Lichtes sind durch Relaxationseffekte beeinflußte Schwankungen der Elektronentemperatur wesentlich beteiligt. Die geringe Variation der Schallgeschwindigkeit mit der Entladungsstromstärke läßt sich wahrscheinlich auf die dabei auftretende Änderung der Neutralgastemperatur zurückführen. Nach vorläufigen Messungen nimmt die Dämpfung des Schalls mit wachsender Entladungsstromstärke etwas zu, was auch auf einen gewissen Einfluß des Ionisationsgrades des untersuchten Niederdruckplasmas auf die Schallausbreitung hindeutet.
Über Stoßwellen (Phänomenologische Betrachtungen)
Authors: Kautzleben H. , Lucke O.
Published: July 2007

Es wird über eine Reihe von Arbeiten über nichtlineare hydromagnetische Wellen, insbesondere die wichtige Klasse der hydromagnetischen Stoßwellen, auf Grund der phänomenologischen Grundgleichungen der Hydromagnetik berichtet. Als Spezialfall dieser Wellen werden zur Orientierung die gewöhnlichen hydrodynamischen Stoßwellen behandelt. Solche Wellen lassen sich ebenfalls in festen Körpern feststellen.

Im hydromagnetischen Medium werden diese Wellen nicht nur durch das Magnetfeld verändert, sondern es treten auch völlig neue Wellentypen auf. Nach einer Übersicht der linearen hydromagnetischen Wellen werden die einfachen ebenen Wellen endlicher Amplitude eingeführt, die bei der Ausbreitung zu hydromagnetischen Stoßwellen führen. Die hydromagnetischen Stoßwellen werden dann als spezielle Lösungen der allgemeinen Grenzbedingungen behandelt. Es werden die Bedingungen für ihre Entwicklungsfähigkeit angegeben. Abschließend wird über die Wechselwirkung hydromagnetischer Stoßwellen berichtet.
Schichterscheinungen der Niederdruckentladung in Neon—Wasserstoffgemischen
Authors: Pfau S. , Rutscher A.
Published: July 2007

Bei einem konstanten Totaldruck (1,8 Torr) sind die charakteristischen Größen der laufenden Schichten einer Niederdruckentladung im Bereich kleiner Stromstärken in Abhängigkeit vom Mischungsverhältnis (Ne/H2) untersucht worden. Auf die positiven laufenden Schichten der Neonentladung haben bereite geringe Mengen Wasserstoff (der Größenordnung 10−2%) einen meßbaren Einfluß. Die maximale Amplifikation dieser Schichten steigt zunächst mit wachsendem H2‐Gehalt. Höhere Prozentsätze (etwa 10%) bewirken eine Dämpfung, so daß sich eine homogene Säule ergibt. Bei noch größeren H2‐Zumischungen zeigt die Säule negative laufende sowie ungedämpfte stehende Schichten. Der Zusammenhang zwischen stehenden und laufenden Schichten, wie er bereits in reinen Gasen ermittelt wurde, konnte weiter untermauert werden.
Bemerkungen zur Theorie der solaren Typ IV‐Bursts
Authors: Böhme A.
Published: July 2007

Using some formulae of Takakura it is shown, that the type IV bursts at decimeter waves may be interpreted by synchrotron radiation. Great helical angles of the electron orbits are necessary for the emission of a strong ordinary wave; such great helical angles are obtained, if the magnetic field strength in the sources of the type IV bursts at decimeter waves is assumed to 200–300 gauss and the helical angles are calculated from the adiabatic invariance of the magnetic moment\documentclass{article}\pagestyle{empty}\begin{document}$ |\overrightarrow \mu |\, = \,\frac{1}{2}\,\frac{{m\,\upsilon ^2 \, \bot }}{B} $\end{document}of the electron in its orbit. The opinion of Tanaka and Kakinuma is discussed, that there may be some relations between the storm continua and the type IV bursts at decimeter waves. It is shown, that the storm continua and the type IV bursts at decimeter waves are caused by different mechanisms.
Die Dämpfung von Schallwellen in der Entladungssäule des Niederdruckplasmas
Authors: Hayess Erhard
Published: July 2007

Die Versuchsanordnung besteht aus einem Entladungsrohr, in dem das Plasma mittels einer Hilfselektrode mit Rechteckimpulsen hoher Spannung gestört wird. Die Kenndaten der dabei entstehenden Schallwelle lassen sich infolge der Lichtmodulation des Plasmas photoelektrisch ausmessen. Mit dieser Anordnung wird die Dämpfung der Schallwelle in Abhängigkeit vom Gasdruck und von der Stromstärke in Xenon untersucht. Dabei zeigt sich nur eine geringe Beeinflussung des Dämpfungskoeffizienten durch die Entladungsstromstärke. Eine Vergrößerung des Gasdruckes jedoch führt zu einer merklichen Verminderung der Dämpfung.

Die Messungen werden mit theoretischen Ergebnissen anderer Autoren verglichen. Es zeigt sich, daß von allen Mechanismen, die im Neutralgas eine Schalldämpfung hervorrufen können, die Wanddämpfung in engen Rohren für diese Messungen allein von Bedeutung ist. Die bei Anwesenheit von Ladungsträgern wirksame Stoßdämpfung ist bei den geringen Ionisierungsgraden (etwa 10−6 bis 10−3) ebenfalls vernachlässigbar.
Die positive Säule der Argon‐Niederdruckentladung im Übergangsbereich III
Authors: Wojaczek Karl
Published: July 2007

Sogar bei Entladungsstromstärken der Größenordnung einiger Ampere kann für die Elektronen in der positiven Säule der Argon‐Niederdruckentladung nur bis zu Energien unterhalb der tiefsten Anregungsenergie Ua mit einer Maxwellverteilung der Geschwindigkeiten gerechnet werden. Bei Energien oberhalb Ua besteht ein so großes Defizit an schnellen Elektronen, daß direktionisierende Stoffe der Elektronen mit unangeregten Atomen keine Rolle spielen können und die Ladungsträgerproduktion stufenweise über langlebige angeregte Atome erfolgen muß. Die Beseitigung der angeregten Atome erfolgt einerseits durch die Stufenionisation selbst, andererseits durch Strahlungsprozesse, während Stöße zweiter Art mit langsamen Elektronen keine Rolle spielen. Die erzeugten Ladungsträger rekombinieren an der Rohrwand.

In vorliegender Arbeit wird eine diesen Vorstellungen entsprechende Theorie der positiven Säule entwickelt. Die Anpassung der nach dieser Theorie berechneten Elektronentemperaturen und Potentialgradienten an die im Puppschen Übergangsbereich in Argon gemessenen Werte gestattet, in gewissem Umfange Schlüsse auf die Stärke der Elektronenwechselwirkung, auf die Querschnitte für Stufenanregung und Stufenionisation bzw. auf die effektive Strahlungslebensdauer der angeregten Atome zu ziehen. Die entwickelten Vorstellungen bewähren sich bei der Diskussion einiger für die Schichtungsbildung maßgeblicher Großen, die die Abhängigkeit der Ionisationsrate und der Energieverlustrate von Elektronentemperatur und Elektronenkonzentration charakterisieren.