bluuebunny/crossref_metadata_2025 huggingface dataset:
Prädiktive Regelung mit Neuronalen Netzen (Predictive Control with Neural Networks)
Authors: Bollig A.
Published: December 2003

Dieser Beitrag beschreibt den theoretischen Hintergrund eines prädiktiven Regelungskonzepts, welches für die Regelung der Einschweißtiefe beim Laserstrahlschweißen entwickelt wurde. Durch die Regelung wird die eingebrachte Laserleistung unter Berücksichtigung der Vorschubgeschwindigkeit optimiert. Zur Modellierung des nichtlinearen Schweißprozesses wird ein Künstliches Neuronales Netz (KNN) genutzt. Der GPC-Algorithmus wird mit einem linearen Modell verwendet, welches in jedem Abtastschritt durch Linearisierung des KNN gewonnen wird. Eine Erweiterungsmöglichkeit des Trainings um lokale Modelleigenschaften wird vorgestellt.
Absatzerkennung bei autonomen mobilen Robotern (Step Detection for Autonomous Mobile Robots)
Authors: Bechtel Peter , Schatz Andreas , Dieterle Lars , Adamy Jürgen
Published: December 2003

In dieser Arbeit wird ein Absatzerkennungssystem für mobile Roboter vorgestellt, das die Gefahr des Absturzes an Absätzen ausschließt. Ausgehend von den allgemeinen Anforderungen wurde ein Sensorsystem, das auf einer Kombination von zwei Infrarotsensortypen basiert, und ein Fahralgorithmus zur Gefahrenvermeidung entwickelt. Die Methode ist weitgehend unabhängig vom Typ des radgetriebenen Roboters. Das System funktioniert ohne Vorwissen über das Aussehen der Absätze.
Vergleich von Modelica und Matlab anhand der Modellbildung eines Dieselmotors (Comparison of Modelica and Matlab by means of the Model of a Diesel Engine)
Authors: Richert Felix , Rückert Joachim , Schloßer Axel
Published: December 2003

Dieser Beitrag befasst sich mit der objektorientierten Modellbildung und Simulation eines Dieselmotors unter Modelica/Dymola, dem Vergleich mit Matlab/Simulink sowie den jeweiligen programmspezifischen Besonderheiten bei der Handhabung. Die objektorientierte Modellierungssprache Modelica bietet gegenüber der meist üblichen, signalbasierten Modellierung einen vielversprechenden Ansatz, bei dem das Simulationsprogramm die notwendigen Gleichungsmanipulationen und Strukturierung der Signale eines Modells soweit wie möglich vornimmt. Um zu untersuchen, ob dieser Anspruch auch bei komplexen Modellen erfüllt wird, ist ein in Matlab/Simulink vorhandenes Modell eines Dieselmotors nach Modelica/Dymola portiert worden.
Optimale Regelverfahren zur automatischen Bahnführung von Binnenschiffen (Automatic Track-Keeping on Waterways Using Optimal Control)
Authors: Wahl Anja , Gilles Ernst-Dieter
Published: December 2003

Die automatische Bahnführung von Binnenschiffen ist Inhalt des vorliegenden Beitrags. Zur Lösung der Bahnregelaufgabe werden drei unterschiedliche Regelstrategien: eine linear optimale Zustandsregelung mit Führungsgrößenaufschaltung, eine nichtlineare modellprädiktive Regelung und eine Optimalsteuerung mit unterlagerter Zustandsregelung entworfen. Diese Verfahren werden nicht nur mit Hilfe von Simulationen, sondern auch anhand der Ergebnisse von Versuchsfahrten untersucht, verglichen und bewertet. Ziel einer automatischen Streckenfahrt ist, den Schiffsführer bei seiner Routinearbeit zu entlasten und somit zu einer Erhöhung der Sicherheit des Verkehrs auf Binnenwasserstraßen beizutragen.
Flachheitsbasierte Bahnsteuerung von seilgeführten Handhabungssystemen (Flatness-Based Control of Cable Suspension Manipulators)
Authors: Maier Thomas , Woernle Christoph
Published: December 2003

Bei seilgeführten Handhabungssystemen wird eine Nutzlastplattform an mehreren räumlich angeordneten Seilen geführt, deren Seilwinden wie bei Kranen auf Laufkatzen angeordnet sind. Für kinematisch unbestimmte Systeme, bei denen die Lage der Nutzlastplattform durch die Längen der Seile geometrisch nicht festgelegt ist, wird auf der Grundlage der Flachheitseigenschaft eine Feedforward-Bahnsteuerung entworfen, durch welche die Nutzlastplattform pendelfrei entlang gewünschter Trajektorien im Raum geführt wird. Die Vorgehensweise wird am Beispiel eines Brückenkrans eingeführt und für die Bahnsteuerung eines experimentellen Handhabungssystems mit Lastführung durch drei Seile erweitert. Versuchsergebnisse bestätigen die Wirksamkeit des gewählten Ansatzes.
Berechnung der Bevölkerungsentwicklung mittels eines zeitvarianten diskreten Dynamikmodells (Estimation of the Populations´ Development by Means of a Timevariant, Discrete Dynamic Model)
Authors: Frederking Thilo , Laipple Bernd , Welfonder Ernst
Published: December 2003

Es werden die Algorithmen zur diskreten Berechnung der zeitlich sich ändernden Altersstruktur einer Bevölkerung hergeleitet und die Funktionsweise des resultierenden Dynamikmodells anhand eines Blockschaltbildes veranschaulicht. Der Test des detaillierten Bevölkerungsmodells erfolgt anhand des Vergleichs von "Messung" und "Rechnung", d. h. von statistisch erfassten und simulierten Bevölkerungsverteilungen. Betrachtet werden die unterschiedlichen Bevölkerungsentwicklungen von "Deutschland", "Indien" und "China" in der Vergangenheit und Zukunft.
Anwendung von modellbasierter prädiktiver Regelung und Methoden der hybriden Systeme zur optimalen Produktionsplanung (Using Model Predictive Control and Hybrid Systems for Optimal Scheduling of Industrial Processes)
Authors: Gallestey Eduardo , Stothert Alec , Castagnoli Dario , Ferrari-Trecate Giancarlo , Morari Manfred
Published: December 2003

Optimal (re)scheduling of production in industrial processes increases economic efficiency through timely and optimal use of limited resources. In this article an approach to scheduling based on the use of hybrid systems and model predictive control is presented. Modelling flexibility, acceptable computational times, and optimal disturbance rejection are the key advantages of the approach. The main ideas are illustrated with two industrial applications.
Zur Vergröberung/Verfeinerung von Petri-Netzen bei der Zuverlässigkeits-Modellbildung (On Coarsening/Refining Petri Nets for Reliability Modeling)
Authors: Schneeweiss Winfrid
Published: December 2003

Petri-Netze bieten unter anderem den Vorteil einer einheitlichen bildlichen Beschreibung dynamischer Systeme auf allen Systemebenen. Oft möchte man aus gut verstandenen Teilmodellen Gesamtmodelle großer, komplexer Systeme gewinnen, wobei Feinheiten unterer Systemebenen wegfallen sollen. Oder man möchte umgekehrt einen Grobentwurf sukzessive verfeinern. Hier werden Probleme, die bei dieser Vergröberung/Verfeinerung von Petri-Netzen auftreten können, analysiert. Es reicht nicht das Definieren neuer bzw. das Aufspalten “grober” Transitionen, denn auch Kanten müssen “gebündelt” bzw. aufgespalten werden. Es wird gezeigt: Entscheidend ist, dass auf jeder Systemebene eindeutige Petri-Netz-Plätze (-Stellen) für “System intakt” bzw. “System defekt” konstruiert werden.
Production of235Np,236Pu and237Puvianuclear reactions on235,236,238U and237Np targets
Authors: Aaltonen J. , Dendooven P. , Gromova E. A. , Heselius S.-J. , Jakovlev V. A. , Trzaska W. H.
Published: December 2003

A summary of methods for cyclotron production of235Np (396.1d),236Pu (2.858y) and237Pu (45.2d)vianuclear reactions with protons and3He-ions on235,236,238U and237Np targets in wide energy ranges is given. Methods for the chemical separation and purification of these nuclides from the irradiated uranium and neptunium targets are described. Cross sections, yields and radionuclidic purities of235Np,236Pu and237Pu are presented and compared with literature data on the nuclear reactions leading to these radionuclides. The nuclear reactions with the so far highest known yields of235Np,236Pu and237Pu are determined:236U(p,2n)235Np,237Np(p,2n+pnβ-)236Pu and237Np(p,n)237Pu, respectively. The highest radionuclidic purity of235Np,236Pu and237Pu tracers can be reached with the236U(p,2n)235Np,236U(p,nβ-)236Pu and237Np(3He,t)237Pu reactions, respectively. In addition new cross sections and yield data of the236U(3He,p3n)235Np reaction in the energy range 42.4–60 MeV are given.
Spectroscopic study (TRLFS and EXAFS) of the kinetics of An(III)/Ln(III) humate interaction
Authors: Monsallier Jean-Marc , Artinger Robert , Denecke Melissa A. , Scherbaum Franz J. , Buckau Gunnar , Kim Jae-Il
Published: December 2003

Humic acid metal ion interaction shows a complex kinetic behavior. Dissociation kinetics reported in the literature reach from hours to basically irreversibility. Different suggestions for the responsible mechanisms have been made. One possibility is variations in the metal ion humate complex environment, subject to this study. The dissociation kinetics of Eu(III)/Tb(III)/Cm(III) humate complexes is investigated with purified humic acid solution (Gohy-573(HA), pH=6.0,I=0.1M (NaClO4)) and a humic rich groundwater (Gohy-532, pH=7.5). The different kinetic modes are verified by both scavenging of dissociated metal ions by an cation exchanger added after different metal ion humic acid contact times, and isotope exchange under stationary conditions,i.e.without change in metal ion humic acid ratio. The metal ion humate complex environment is studied by time resolved laser-induced laser fluorescence spectroscopy (TRLFS) and EXAFS. TRLFS shows that slower dissociating Cm(III) humate has a peak maximum at 600.5nm contrary to the fast dissociating ones with a peak maximum around 602.8nm. EXAFS also shows differences between slow and fast dissociating complexes (Tb(III), with an average Tb(III) oxygen distance of 2.37Å for an equilibrium mixture, and 2.33Å for only the slow dissociating complex. TRLFS shows that complexes with fast and slow dissociation kinetics have returned to the original distribution three days after removal of the fast dissociating metal ions and thus the different kinetic modes are in exchange equilibrium with each other. Furthermore, the isotope exchange investigations verify that humic acid europium flocculate basically behaves like dissolved/dispersed humate complexes.
Sorption and desorption of neptunium(V) on loess: batch and column experiments
Authors: Weijuan Li , Zuyi Tao , Liangtian Guo , Shushen Li
Published: December 2003

The sorption and desorption isotherms and the corresponding distribution coefficients (Kd, mL/g) of Np(V) for untreated loess and three kinds of treated loesses were determined by using the batch technique at moderate concentrations (∼10-5mol/L) under ambient aerobic conditions in the presence of 0.01mol/L CaCl2. For the treated loesses, selective extraction methods were used to remove CaCO3and organic matter (OM) from the loess. The isotherms were analyzed with the Freundlich equation. The relative contributions of OM and CaCO3to the Np(V) sorption on the loess were investigated from the parameters of the Freundlich equation. The effects of adding fulvic acid (FA) from the loess and the carbonate in solution on the sorption of neptunium(V) on the loess were studied. The breakthrough curves (BTCs) and displacement curves (DPCs) of Np(V) on the untreated loess column and on the treated loess columns were determined under ambient aerobic conditions at moderate concentration (1.1×10-4mol/L) in the presence of 0.01mol/L CaCl2. The results of column experiments are in accord with the results of batch experiments. It was found that (1) Np(V) in the loess under the present experimental conditions was relatively mobile and the distribution coefficients were relatively low at moderate concentrations, (2) the sorption/desorption hysteresis of Np(V) on the loess occurs, (3) the sorption of Np(V) on the loess was mainly determined by the clay minerals, (4) the addition of FA or carbonate in the aqueous solutions had an obvious positive effect on the Np(V) sorption on the loess, (5) the retardation of Np(V) migration in the loess at moderate concentrations was inconsiderable.
Characterization of U(VI)-Acidithiobacillus ferrooxidans complexes using EXAFS, transmission electron microscopy, and energy-dispersive X-ray analysis
Authors: Merroun Mohamed , Hennig C. , Rossberg A. , Reich T. , Selenska-Pobell S.
Published: December 2003

We used a combination of Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy, Transmission Electron Microscopy (TEM) and Energy-Dispersive X-ray (EDX) analysis to conduct molecular scale studies on U(VI) interaction with three recently described eco-types of Acidithiobacillus ferrooxidans. On the basis of the information obtained by using these methods, we concluded that uranyl phosphate complexes were formed by the cells of the three eco-types studied. The uranium accumulated by A. ferrooxidans cells was located mainly within the extracellular polysaccharides, and on the cell wall. Smaller amounts were also observed in the cytoplasm.
Synergistic extraction of uranium(VI) by 2-hydroxy-1-naphthaldehyde thiosemicarbazone and several neutral donors
Authors: Banerjee S. , Bhar M. , Basu S.
Published: December 2003

The extraction behaviour of U (VI) from an aqueous nitric acid medium employing a 2-hydroxy-1-naphthaldehyde thiosemicarbazone in ethyl acetate has been studied in presence of different neutral donors like trioctyl phosphine oxide (TOPO), dimethyl sulphoxide (DMSO) and trioctyl amine (TOA). The extraction constant (log k
ex) for the binary organic phases UO2·A·X (where A=ligand, X=NO3
-1) was found to be 1.976 which is by far the largest value amongst known values for the thiosemicarbazone. The overall equilibrium constant (log K) for the ternary complexes UO2A(NO3)·TOPO, UO2A(NO3)·TOA and UO2A(NO3)·DMSO were estimated to be 6.06, 6.77 and 4.95, respectively. The effect of different diluents on the extraction behaviour has also been studied.
Complex formation of Tb3+with glycolate,D-gluconate andα-isosaccharinate in neutral aqueous perchlorate solutions
Authors: Zhernosekov K. P. , Mauerhofer E. , Getahun G. , Warwick Peter , Rösch Frank
Published: December 2003

An electromigration technique was used for measurements of metal-ligand formation constants of non-carrier-free160Tb3+with glycolate,D-gluconate andα-isosaccharinate ligands. The overall ion mobilities of Tb at different concentrations of the ligands were measured in chemically inert perchlorate solutions (pH 7 andT= 298.1K) with an overall ionic strengthμ= 0.1. The stepwise stoichiometric stability constants are: Tb3+/glycolate: logK1=2.72(18), logK2=1.73(19), logK3= 1.12(17), Tb3+/D-gluconate: logK1=2.96(11), logK2=2.60(11), logK3=1.13(9), Tb3+/α-ISA: logK1=3.07(8), logK2= 2.69(11), logK3= 1.80(12).
Sorption kinetics of cesium on hydrous titanium dioxide
Authors: Altaş Y. , Tel H. , Yaprak G.
Published: December 2003

Two types of hydrous titanium dioxide possessing different surface properties were prepared and characterized to study the sorption kinetics of cesium. The effect of pH on the adsorption capacity were determined in both type sorbents and the maximum adsorption percentage of cesium were observed at pH 12. To elucidate the kinetics of ion-exchange reaction on hydrous titanium dioxide, the isotopic exchange rates of cesium ions between hydrous titanium dioxides and aqueous solutions were measured radiochemically and compared with each other. The diffusion coefficients of Cs+ ion for Type1 and Type2 titanium dioxides at pH 12 were calculated as 2.79×10-11m2s-1 and 1.52×10-11m2s-1, respectively, under particle diffusion controlled conditions.
Complexation of 188Re-phosphonates: in vitro and in vivo studies
Authors: Faintuch B. L. , Faintuch S. , Muramoto E.
Published: December 2003

MDP (methylenediphosphonate) and HEDP (hydroxyethylidene diphosphonate), both diphosphonates, and EDTMP (ethylenediamine tetramethylene phosphonic acid), a tetraphosphonate ligand, have been previously labeled with 188Re for use in metastatic bone-pain palliation. The aim of this study was a comparison between the three complexes 188Re-MDP, 188Re-HEDP and 188Re-EDTMP concerning the complexation conditions, in order to achieve maximum yield, stability and bone uptake. Methods: MDP was dissolved in water and HEDP and EDTMP were dissolved in NaOH 1N followed by reduction of pH with HCl 1N. To all mixtures stannous chloride and 188Re4
- were added in a nitrogen atmosphere. The preparations were heated in boiling water bath for 15min. Yield as well as radiochemical stability was estimated by ITLC. Different concentrations of phosphonates and stannous chloride were evaluated. Biodistribution studies in Swiss mice were done for the three 188Re-phosphonates that presented the best radiochemical yield. The optimal ligand concentration for maximum complexation was 85.2mM for MDP, 72.8mM for HEDP and 45.8mM for EDTMP. The best amount of SnCl2·2H2O} was 1.5mg/mL for 188Re-HEDP and 1mg/mL for both 188Re-MDP and 188Re-EDTMP. In these conditons the three complexes showed a complexation rate above 95. Reasonable radiochemical stability for 24 hours was achieved by 188Re-EDTMP when employing ascorbic acid. All products showed a great uptake by the kidneys. 188Re-EDTMP had the greatest uptake by femur (3.1±0.2 ID/g) followed by 188Re-MDP (1.2±0.1 ID/g) and 188Re-HEDP (1.0±0.1 ID/g), 4 hours post injection. 188Re-EDTMP displayed a femur bone/muscle ratio of 28.5, 188Re-MDP 4.9 and 188Re-HEDP 4.9. In conclusion 188Re-EDTMP demonstrated the best potential as a radiopharmaceutical for bone cancer pain relief, encouraging further dosimetric studies and clinical trials.
Production and radioassay of Tc-94m for PET studies
Authors: Szajek Lawrence P. , Der M. , Divel J. , Huang B. X. , Plascjak P. , Eckelman W. C.
Published: December 2003

The radionuclide Tc-94m with its positron branching ratio of 72, positron end-point energy of 2.47MeV, and relatively short half-life of 52 minutes is suitable for quantitative measurements using PET. Tc-94m can be produced by proton bombardment of isotopically enriched [Mo-94]MoO3. We prepare Tc-94m as pertechnetate in saline solution using a wet-chemical separation procedure employing a semi-automated apparatus. Tc-94m sestamibi and other radiopharmaceuticals are routinely produced from this reagent.
Speciation in solution: interaction between calixarene derivatives and lanthanides(III)
Authors: Arnaud-Neu Françoise
Published: December 2003

The importance of stability constant determination for the calculation of speciation diagrams is illustrated through several examples pertaining to the coordination chemistry in solution of trivalent lanthanides with chemically modified calixarene derivatives substituted either at the wide or the narrow rim by carboxylic acid, glycine or CMPO moieties. The influence of the analytical composition of the systems investigated is particularly analyzed.
Structure solution with PATSEE
Authors: Wagner K. , Hirschler J. , Egert E.
Published: December 2003

Patterson search is a powerful tool for solving difficult crystal structures since it actively uses chemical information. Our program PATSEE, which attempts to combine the merits of Patterson and direct methods in order to locate a fragment with known geometry in the unit cell, has solved a large number of crystal structures during the last decade and proved to be reliable and widely applicable. We have tested PATSEE successfully on 20 structures of different size and complexity contained in a test data bank using fragments either taken from related crystal structures or calculated by force-field methods. Even structures with several torsional degrees of freedom (like those of oligopeptides) could be solved convincingly. As a result, general experiences – such as requirements for the minimum size and the accuracy of a search fragment, the reliability of the various figures of merit, the chances to locate single atoms and to tackle larger structures – were gained, which should help in finding an optimum strategy for the solution of problem structures with PATSEE.
The quasicrystal-to-crystal transformation. II. Landau theory
Authors: Beraha L. , Steurer Walter , Perez-Mato J. M.
Published: December 2003

A phenomenological description of the quasicrystal-to-crystal transformation is presented in terms of Landau theory. The basic idea is to describe the structures of quasicrystals as incommensurately modulated structures and to use the tools developed for phase transitions of this kind. The usefulness of this description is demonstrated on quasiperiodic model structures: the one-dimensional (1D) Fibonacci sequence and the 2D Penrose tiling. The transformation to periodic structures is discussed generally for rational approximants.
Superstructure of strontium chromate aluminate sodalite at low temperatures
Authors: Többens D. M. , Depmeier W.
Published: December 2003

At high temperatures yellow strontium chromate aluminate sodalite Sr8[Al12O24](CrO4)2 has cubic symmetry with orientational disorder of the CrO4
2--ions within the sodalite cages. The existence of two phase transitions at 299K and 289K, which result in superstructures of tetragonal and orthorhombic symmetry, respectively, is well known. In this work we describe the crystal structure of the orthorhombic low temperature phase which was determined from neutron and x-ray powder diffraction. Additional information from 27Al-MAS-NMR spectra and the Monte-Carlo-method was used to get a starting model for the structure refinement. In the orthorhombic phase the CrO4-tetrahedra are fully ordered. Two thirds of the rings of four AlO4-tetrahedra forming the sodalite framework are nearly undistorted. The remaining, distorted, rings form chains parallel to the a-axis. The distortion of the rings is of a type which occurs in other aluminate sodalite structures as well and is known as the shearing mechanism. Despite of the different symmetry the structure of this phase is similar to the structure of strontium tungstate aluminate sodalite. The characteristic differences can be explained by the smaller size of the CrO4-tetrahedra.
The structure of the palladium-rich boride Pd5B (Pd16B3)
Authors: Ellner M. , Beck M. , Mittemeijer E. J.
Published: December 2003

The low-temperature boride Pd5B (Pd16B3) formscongruently from the corresponding interstitial solid solu-tion Pd(B) (Pearson-Parthé symbol cF(8-x), space group Fm3̅m) at 658 K. The structure of Pd5B has been investigated by X-ray powder diffraction yielding the following structural data: I4/mmm, tI2.38; unit cell parameters a = 0.28490(4) nm, c = 0.40038(9) nm, c/a = 1.405 < √2, with the occupation 2Pd (a) and 0.19 x 2B (b). The crystal chemical data of Pd5B and some other homeotypic interstitial compounds of transition metals have been compared.
Crystal structure and twinning of Bi4O5Br2
Authors: Keller E. , Ketterer J. , Krämer V.
Published: December 2003

The monoclinic crystal structure of Bi4O5Br2has been determined from 1:1 twinned crystals pretending orthorhombic symmetry. Bi4O5Br2crystallizes with space groupP21(no. 4),Z=4,a=14.539(4),b=5.605(1),c=10.782(3) Å,β= 97.75(7)°. Its structure shows much closer relationships to the structure ofα-Bi5O7I than to that one of the homologuous compound Bi4O5Cl2.
Synthesis and properties of 6-fluoro-7-chloro-4-oxo-4H-chromene 3-carboxylic acid. X-ray structure of achiral heterotopic 3-diethoxymethyl-6-fluoro-7-chloro-4-oxo-4H-chromene
Authors: Barili P. L. , Valenti P. , Artali R. , Bombieri G. , Da Re P.
Published: December 2003

Synthesis and reactions of 6-chloro-7-fluoro-4-oxo-4H-chromene-3-carboxylic acid are described. The molecular structure of its achiral heterotopic 3-diethoxy-methyl precursor has been determined by NMR spectroscopy and X-ray crystallography. C14H14ClFO4 is monoclinic, space group P21/a, with unit cell dimensions a = 14.923(5), b = 6.615(2), c = 14.921(5) Å, β = 101.44(3)°, V = 1443.7(8) Å3, Z = 4, D
calc. = 1.383 g/cm3.
Thermal expansion of decagonal Al70.7Co13.3Ni16.0 in the temperature range 15–300 K
Authors: Kupsch A. , Meyer D. C. , Gille P. , Paufler P.
Published: December 2003

The temperature dependence of lattice parameters a in the quasiperiodic plane and c in the periodic direction of decagonal Al70.7Co13.3Ni16.0 was probed using X-ray powder diffraction in the temperature range 15–300 K. Both parameters were fitted by means of positions of 22 Bragg reflections for each temperature. Temperature dependences were modelled best by second order polynomials leading to linear thermal coefficients α(T) = 8.1(33) · 10–7K–1 + 3.9(2)· 10–8K–2
T in the quasiperiodic plane and γ(T) = 1.7(6) · 10–6K–1 + 3.8(3) · 10–8K–2
T in the periodic direction, respectively. Thus we found the anisotropy ratio γ(T)/α(T) to decrease with increasing temperature from 1.10 (at 15 K) to 1.19 (at 300 K). Besides pecularities around 150 K indicating an intermediate phase formed by superordering, we observed deviations from the general smooth course between 15K and 50K for both lattice parameters.
The intermediate phase of strontium chromate aluminate sodalite
Authors: Többens D. M. , Depmeier W.
Published: December 2003

At high temperatures yellow strontium chromate aluminate sodalite Sr8[Al12O24](CrO4)2 has cubic symmetry with orientational disorder of the CrO4
2--ions within the sodalite cages. The existence of two phase transitions at 299 K and 289 K, which result in superstructures of tetragonal and orthorhombic symmetry, respectively, is well known. The structure of the orthorhombic low-temperature phase has been solved recently. In this work we discuss the crystal structure of the intermediate phase and its determination from neutron and x-ray powder diffraction data. The structure of this phase shows only very small distortions of the framework of AlO4-tetrahedra. The CrO4-tetrahedra within the sodalite cages are partially ordered. The observed distribution of their orientations can be described as a combination of those of the low- and the high-temperature phase. 27Al-MAS-NMR spectra reveal the dynamic nature of the structure.
Crystal structure and elastic properties of betaine fumarate and of betaine maleate, two isomers of ((CH3)3NCH2COOH . OOC(CH)2COOH
Authors: Haussühl E. , Schreuer J.
Published: December 2003

X-ray structure analyses of orthorhombic betaine fumarate and monoclinic betaine maleate yielded space group Pnma, a
1=26.510(5) Å, a
2=6.684(1)Å, a
3=6.376(1)Å, Z=4, ρ
calc=1.371g cm-3, ρ
obs=1.370 g cm-3 and, respectively, space group P21/n, a
1=6.132(1)Å, a
2=10.823(2)Å, a
3=17.246(3)Å, α
2=92.87(3)°, Z=4, ρ
calc=1.355 g cm-3, ρ
obs=1.351 g cm-3. In both compounds the hydrogen betaine cations are joined to the corresponding anions by strong H-bonds with O···O distances of about 2.48Å. Large single crystals of optical quality of betaine maleate have been grown from aqueous solutions. Further, we determined their coefficients of thermal expansion and their elastic and thermoelastic constants. In comparison to the pronounced anisotropy of the mechanical properties of betaine fumarate, the elastic constants of betaine, maleate appear only slightly anisotropic. Between 80 K and 305 K no phase transision could be detected in betaine maleate. However, softening of certain acoustic modes at temperatures below about 160 K might be a hint at structural instabilities at even lower temperatures.
Synthesis, electronic and crystal structure of a new organic semiconductor tetramethyltetrathiafulvalene-trinitroresorcinol (2:1), (TMTTF)2(C6H2N3O8)
Authors: Abashev G. G. , Gritsenko V. V. , Kazheva O. N. , Tenishev A. G. , Canadell E. , Dyachenko O. A.
Published: December 2003

A new organic semiconductor with trinitroresor-cinol as the anion, (TMTTF)2(C6H2N3O8) (1) (TMTTF: tetramethyltetrathiafulvalene),

has been synthesized and its crystal structure has been investigated at room and low temperatures (295 and 110 K). The crystal structure of 1 is formed by one-dimensional stacks of cation-radicals (TMTTF)+1/2 separated by trinitroresorcinol anions (C6H2N3O8)–. This novel salt reveals semiconducting properties. Tight-binding band structure calculations for 1 have been carried out in order to understand the charge distribution among the different donors.
Synthesis and crystal structure determination of 6-phenyl-5-phenylsulfonyl-1,2,3,4-tetrahydropyrimidine-2-thione from neutron powder diffraction data
Authors: Rybakov V. , Chernyshev V. V. , Tafeenko V. A. , Shutalev A. D. , Kurbakov A. I. , Trounov V. A.
Published: December 2003

The title compound was synthesized by reaction of N-(azidomethyl)thiourea or N-(tosylmethyl)thiourea with α-phenylsulfonylacetophenone in the presence of sodium hydride followed by p-toluenesulfonic acid treatment of the obtained N-[3-oxo-3-phenyl-2-(phenylsulfonyl)propyl]thiourea. The molecular and crystal structure of 6-phenyl-5-phenylsulfonyl-1,2,3,4-tetrahydropyrimidine-2-thione (C14H13N2S2O2; space group P21/a; Z=4; a=17.396(1) Å, b=5.887(1) Å, c=15.665(2) Å, β=104.89(1)o) have been determined and refined from neutron (the neutron diffraction was very effective for describing of this system due to using of partial hydrogen-deuterium substitution) powder diffraction data using grid search and a Rietveld procedures. The crystal structure is formed by centrosymmetric hydrogen-bonded dimers along a axis.
A contribution to the crystal chemistry of DL-malates
Authors: Fleck Michel , Tillmanns E. , Bohatý L.
Published: December 2003

The crystal structures of twelve different DL-malates have been determined and refined from single-crystal X-ray diffraction data. In addition, powder diffrac-tion data were used for the refinement of the lattice pa-rameters. The title compounds are the neutral DL-malates Li2(C4H4O5)·2H2O (space group P21/c), Mn(C4H4O5)·3H2O (Pbca), Cd(C4H4O5)·3H2O (P21/n), Sr2(C4H4O5)2·5H2O (P1̅) and Ba(C4H4O5). 2H2O (P1̅) as well as the acid DL-malates RbH(C4H4O5) (Fdd2), CsH(C4H4O5)·H2O (P21/n), MgH2(C4H4O5)2·4H2O (C2/c), CaH2(C4H4O5)2·2H2O (C2/c), ZnH2(C4H5O5)2·4H2O (C2/c), LiH3(C4H4O5)2 (P1̅), CsH3(C4H4O5)2 (P1̅). A comparison of DL-malate structures and a scheme of structural characterization according to cation polyhedra connection is proposed.
Absorption correction for crystal-environment attachments from direction cosines
Authors: Katrusiak Andrzej
Published: December 2003

A simple procedure for deriving absorption corrections for crystal-environment diffractometer attachments of radial symmetry, like high-pressure cells, cryostats, furnaces or capillaries, from the direction cosines of the primary and diffracted beams is presented. This method is applicable irrespective of the diffractometer type, equally for point and area detectors.
Monthly distribution of menarche among schoolgirls from a municipality in Southeastern Brazil
Authors: Tavares Carlos H.F. , Barbieri Marco A. , Bettiol Heloisa , Barbieri Marisa R. , De Souza Luiz
Published: December 2003

We studied the monthly distribution of menarche among schoolgirls from Barrinha, Brazil, a municipality of rural characteristics in the process of transition to urbanization, economically dependent on sugar cane culture and processing. The association between season of the year, month of the year, and birth month and the occurrence of menarche was evaluated. The schoolgirls who provided the date of menarche (month and year) by the recall method and who had menarche up to 36 months before the interview were selected for analysis (460 girls). The correlations between month of occurrence of menarche and month of birth and between menarche and seasons of the year were determined by the chi‐square test and the mean monthly ages at menarche were compared by Student's t‐test, with a significance level of 0.05. There was a correlation between month of birth and month at menarche, with a peak of occurrence of menarche in December not affected by the menstruating patterns of maturation, but no correlation between menarche and seasons of the year. The difference between mean age at menarche in December (spring–summer transition) and in June (autumn–winter transition) was not significant. Mean age at menarche during the month following school vacations was lower. We conclude that situations of stress–relaxation transition, such as end of the school year, beginning of school vacation, and, perhaps most important, the socioeconomic factor—the end of the sugar cane harvest, when rural workers receive their final payments—favor the occurrence of the peak of menarche in December. Am. J. Hum. Biol. 16:17–23, 2004. © 2003 Wiley‐Liss, Inc.
Prevalence of eight molecular markers associated with thrombotic diseases in six Amerindian tribes and two African groups of Costa Rica
Authors: Herrmann Falko H. , Salazar‐Sánchez Lizbeth , Schuster Gudrun , Jiménez‐Arce Gerardo , Grimm Rita , Gomez Xinia , Chavez Mario , Wulff Karin , Schröder Winnie
Published: December 2003

Individuals belonging to six different Amerindian tribes and two African groups of Costa Rica were genotyped for factor V Leiden (FV), factor V haplotype HR2 (FV HR2), Factor II 20210G>A (FII), the methylenetetrahydrofolate reductase (MTHFR), factor VII polymorphisms (FVII IVS7, FVII R353Q), factor XIII (FXIII V34L), and the insertion/deletion (I/D) polymorphism of the gene of angiotensin converting enzyme (ACE). Clear differences in the prevalence were found and are first reported. The prevalence of some of the established genetic risk factors was low in Amerindians of Costa Rica (ACE) or even absent (FVL, FII), and others (MTHFR, FVHR2) had an extremely high prevalence. People of African origin carried very rare FVL or FII polymorphisms, but the DD genotype of ACE is the highest reported. Concerning the protective factors, the QQ genotype of FVII R353Q was absent in Amerindians, but the protective 7/7 genotype of FVII IVS7 frequently found. Novel alleles of FVII IVS7 (4, 8, and 9 monomers) were found. Intertribal heterogeneity was observed that may reflect the evolutionary history of these tribal groups and their admixture with other populations. Am. J. Hum. Biol. 16:82–86, 2004. © 2003 Wiley‐Liss, Inc.
Duffy blood group genotyping in French Basques using polymerase chain reaction with allele‐specific primers (PCR‐ASP)
Authors: Bauduer Frédéric , Touinssi Mhammed , Degioanni Anna , Leroux Stéphane , Dutour Olivier , Ducout Louis , De Micco Philippe , Chiaroni Jacques
Published: December 2003

Blood group antigens such as Duffy represent interesting models for population genetics studies. The distribution of the Duffy blood group was determined using PCR in a sample of Basque (n = 126) and non‐Basque (n = 110) patients from the general hospital of the French Basque Country. The frequency of FY*A allele was significantly lower among autochthonous French Basques (P < 0.001). This result, obtained for the first time by PCR analysis in this population, was within the range of previous historical studies in various Basque subpopulations using traditional hemagglutination methods. When compared with European data, our Basque sample demonstrated the lowest FY*A/FY*B ratio, this fact confirming hemotypology data published before the molecular biology era. Our results with FY*X were quite similar to those reported in European populations. Am. J. Hum. Biol. 16:78–81, 2004. © 2003 Wiley‐Liss, Inc.
A new protocol for evaluating putative causes for multiple variables in a spatial setting, illustrated by its application to European cancer rates
Authors: Sokal Robert R. , Oden Neal L. , Rosenberg Michael S. , Thomson Barbara A.
Published: December 2003

We introduce a statistical protocol for analyzing spatially varying data, including putative explanatory variables. The procedures comprise preliminary spatial autocorrelation analysis (from an earlier study), path analysis, clustering of the resulting set of path diagrams, ordination of these diagrams, and confirmatory tests against extrinsic information. To illustrate the application of these methods, we present incidence and mortality rates of 31 organ‐ and sex‐specific cancers in Europe; these rates vary markedly with geography and type of cancer. Additionally, we investigated three factors (ethnohistory, genetics, and geography) putatively affecting these rates. The five variables were correlated separately for the 31 cancers over European reporting stations. We analyzed the correlations by path analysis, k‐means clustering, and nonmetric multidimensional scaling; coefficients of the 31 path diagrams modeling the correlations vary substantially. To simplify interpretation, we grouped the diagrams into five clusters, for which we describe the differential effects of the three putative causes on incidence and mortality. When scaled, the path coefficients intergrade without marked gaps between clusters. Ethnic differences make for differences in cancer rates, even when the populations tested are ancient and complex mixtures. Path analysis usefully decomposes a structural model involving effects and putative causes, and estimates the magnitude of the model's components. Smooth intergradation of the path coefficients suggests the putative causes are the results of multiple forces. Despite this continuity of the path diagrams of the 31 cancers, clustering offers a useful segmentation of the continuum. Etiological and other extrinsic information on the cancers map significantly into the five clusters, demonstrating their epidemiological relevance. Am. J. Hum. Biol. 16:1–16, 2004. © 2003 Wiley‐Liss, Inc.
Month‐of‐birth effect on height and weight in Polish rural children
Authors: Kościński Krzysztof , Krenz‐Niedbała Marta , Kozłowska‐Rajewicz Agnieszka
Published: December 2003

This study investigated a hypothesis of dependence of child height and weight on the month of their birth. The sample comprised 1,241 subjects, 568 boys and 673 girls, age 6–20 years, from villages in Olsztyn Province, Northeast Poland. Individuals' height and weight data were standardized by sex and age to allow grouping of individuals born in the same month irrespective of their sex and age at examination. Subjects born in October to March proved to be significantly taller and heavier than those born in April to September. The magnitude of differences between the semiannual groupings equaled 13.1% of a standard deviation (SD) in height (P = 0.03) and 14.2% of SD in weight (P = 0.02). The month‐of‐birth effect was much stronger for children characterized by high socioeconomic status, where these differences amounted to 39.1% of SD in height (P = 0.02) and 49.4% of SD in weight (P = 0.01). There were no regular changes of the effect with age and no differences between the sexes were found. Fitted cosine functions identified the highest values of examined traits for individuals born in December with the lowest values being found in those born in June. Possible explanations of the month‐of‐birth effect are considered in terms of age categorizing, seasonal variety of growth rates, as well as birth‐related or conception‐related global, hemispheric, and local factors. This study rejects the first two possibilities and suggests this effect requires further research to be conducted in various geographical locations, climates, and cultures, on humans as well as on other species. Am. J. Hum. Biol. 16:31–42, 2004. © 2003 Wiley‐Liss, Inc.
Why are human newborns so fat? Relationship between fatness and brain size at birth [retracted article]
Authors: Correia Hamilton R. , Balseiro Sandra C. , Correia Elisabete R. , Mota Paulo G. , De Areia Manuel L.
Published: December 2003

The plumpness of the human newborn has long been recognized as a trait in need of explanation among researchers. Using a linear regression analysis, we find that head circumference is significantly and positively associated with BMI at birth, after gestational age and birthlength were controlled for, in a sample of 1,069 healthy liveborn routinely delivered at the University Hospital of Coimbra (partial correlation r = 0.409, P < 0.0001). This significant association is consistent with the idea that newborn fatness is related to the higher need of lipids in newborn humans as an energetic and plastic substrate during its accelerated brain growth period. As birthweight and birth head size are associated with head size and cognitive abilities in childhood and adult life, it could be postulated that these cognitive abilities could have acted as selective pressure responsible for the newborn fatness increase in our lineage. Am. J. Hum. Biol. 16:24–30, 2004. © 2003 Wiley‐Liss, Inc.
Binary and microsatellite polymorphisms of the Y‐chromosome in the Mbenzele pygmies from the Central African Republic
Authors: Coia Valentina , Caglià Alessandra , Arredi Barbara , Donati Francesco , Santos Fabrício R. , Pandya Arpita , Taglioli Luca , Paoli Giorgio , Pascali Vincenzo , Destro‐Bisol Giovanni , Tyler‐Smith Chris
Published: December 2003

This study analyzes the variation of six binary polymorphisms and six microsatellites in the Mbenzele Pygmies from the Central African Republic. Five different haplogroups (B2b, E(xE3a), E3a, P and BR(xB2b,DE,P)) were observed, with frequencies ranging from 0.022 (haplogroup P) to 0.609 (haplogroup E3a). A comparison of haplogroup frequencies indicates a close genetic affinity between the Mbenzele and the Biaka Pygmies, a finding consistent with the common origin and the geographical proximity of the two populations. The haplogroups P, BR(xB2b,DE,P) and E(xE3a), which are rare in sub‐Saharan Africa but common in western Eurasia, were observed with frequencies ranging from 0.022 (haplogroup P) to 0.087 (haplogroup E(xE3a)). Thirty different microsatellite haplotypes were detected, with frequencies ranging from 0.022 to 0.152. The Mbenzele share the highest percent of microsatellite haplotypes with the Biaka Pygmies. Five out seven haplotypes which are shared by the Mbenzele and Biaka Pygmies belong to haplogroup E3a, which suggests that they are of Bantu origin. The plot based on Fst genetic distances calculated using microsatellite data provides a picture of population relationships which is in part congruent and in part complementary to that obtained using haplogroup frequencies. Finally, the Mbenzele and Biaka Pygmies were found to be markedly more genetically similar using Y‐chromosomal than autosomal microsatellites. We suggest that this could be due to the higher phylogenetic stability of Y‐chromosome and to the effect of the male‐biased gene flow during the Bantu expansion. Am. J. Hum. Biol. 16:57–67, 2004. © 2003 Wiley‐Liss, Inc.
Contemporary work characteristics, stress, and ill health
Authors: Jamison Cheryl Sorenson , Wallace Michael , Jamison Paul L.
Published: December 2003

This study investigates the relationship between work and ill health resulting from stressors originating in the work environment. The association between work and health has been well‐documented. Factors in the work environment leading to ill health have included generalized psychological stress and/or specific physical environmental characteristics. Data for this study come from a 1998 telephone survey, the Indiana Survey of Work in a Polarized Economy, under the auspices of the Center for Survey Research at Indiana University. The dependent variable is an index that measures ill health among workers; control variables include sociodemographic and lifestyle characteristics of these workers as well as their job characteristics; and the four key independent variables are occupational status, organizational disruption, layoff experience, and educational discordance of the workers. Multiple regression analysis on the entire sample (n = 919) demonstrates that occupational status is negatively associated with ill health, while organizational disruption, layoff experience, and educational discordance are positively associated with it. Separate analyses for male (n = 474) and female (n = 445) respondents find significant sex differences in the effects of the key variables: for males, organizational disruption is positively related to ill health while for women occupational status is negatively related and layoff experience and educational discordance are positively related to ill health. The findings from the present research provide insight into the interrelationship of occupational environment and health within the framework of evolutionary medicine. Am. J. Hum. Biol. 16:43–56, 2004. © 2003 Wiley‐Liss, Inc.
D1S80 VNTR locus genotypes in a population of Southeastern Sicily: Distribution and genetic disequilibrium
Authors: Sciacca Giuseppe , Grillo Agata , Paravizzini Gianluca , Barchitta Martina , Libra Massimo , Emmanuele Giovanni , Callari Daniela , Agodi Antonella , Travali Salvatore
Published: December 2003

Locus D1S80 is one of the best‐known polymorphic loci, showing a variable number of tandem repeats. This article presents the results on D1S80 allele distributions in a sample of 324 unrelated Sicilian individuals, collected and analyzed in two distinct laboratory centers. Although, as expected, the two most frequent alleles were those with 18 and 24 repeat units, the population sample from southeastern Sicily showed a relatively low frequency of allele 29 (2.9%) and allele 31 (3.4%) and a relatively high frequency of allele 25 (6.0%), allele 30 (1.9%), and allele 32 (1.5%) in comparison with other populations. Statistical analysis performed by the five alleles model provided evidence that the population did not follow the Hardy‐Weinberg equilibrium expectations (observed heterozygosity 70.99% vs. expected heterozygosity 76.31%). The calculated F (fixation index), as a measure of heterozygote deficiency or excess, was positive for four allele groups and negative for one allele group. This finding was consistent with a substantial diversity of human ethnic groups when tested with VNTR systems and might represent a genuine inconsistency, not due to a methodological bias. This scenario deserves further investigation, i.e., by performing a short tandem repeat (STR) units analysis on a greater number of loci in the same population sample. Am. J. Hum. Biol. 16:91–94, 2004. © 2003 Wiley‐Liss, Inc.
Interpreting skinfold sums. Use of absolute or relative typical error?
Authors: Woolford Sarah M. , Gore Christopher J.
Published: December 2003

The main aims of this study were to: 1) quantify how divergent the sum of seven skinfolds (Σ7skinfolds) of athletes have to be before a general index of measurement imprecision (typical error, TE) is no longer appropriate to very lean or somewhat overweight athletes, and 2) discuss the application of absolute or relative (TE%) typical errors. The Σ7skinfolds was measured in duplicate on 101 athletes by one level 3 anthropometrist with one calibrated skinfold caliper. The TE and TE% for Σ7skinfolds were calculated for all data (TEALL, TE%ALL), as well as for results less than 50 mm (TE<50, TE%<50), inclusive of 50–74.9 mm (TE50–74.9, TE%50–74.9), inclusive of 75–99.9 mm (TE75–99.9, TE%75–99.9) and 100 mm and greater (TE≥100, TE%≥100). At least 20 samples were taken for each measurement range. Limits of agreement (LoA) at the 68% and 95% confidence level were also calculated for all data and the four skinfold ranges. The TE, TE 68, and 95% LoA increased as a direct function of the total Σ7skinfolds and the general TEALL was inappropriate for TE<50 and TE≥100. In contrast, the %TE was very similar within each confidence level (ranging from 1.6–2.1% and 3.1–4.2% for the 68% and 95% LoA, respectively) regardless of the skinfold total. To minimise inaccurate feedback to individuals, anthropometrists dealing with skinfolds of elite athletes should establish an absolute TE on a homogeneous sample of athletes with a Σ7skinfolds in a narrow band, for instance <50 mm. We also urge prudence in interpreting change in skinfold totals and suggest that the 95% level of confidence is appropriate in most instances. Am. J. Hum. Biol. 16:87–90, 2004. © 2003 Wiley‐Liss, Inc.