bluuebunny/crossref_metadata_2025 huggingface dataset:
Brillouin zone double integrals
Authors: Oriade J. O. O.
Published: December 2004

A semianalytic scheme is proposed for the evaluation of Brillouin zone (BZ) double integrals such as are met in the evaluation of Compton profiles (CPS) and the angular distribution of annihilation photons (ADAPS) obtained in single‐slit positron annihilation experiments. The difficulty that arises due to the jump discontinuities in the momentum density at the generalized Fermi surfaces (FS +HMC), pF = kF + g, where kF is the electron Fermi momentum vector and g is a reciprocal lattice vector, is addressed.
Perturbation calculation on the hydrogen atom in electric and magnetic fields
Authors: Fernández Francisco M. , Castro Eduardo A.
Published: December 2004

A generalization of a perturbation theory without wave function is developed which applies to a hydrogen atom perturbed by magnetic and electric fields. A double perturbation expansion for the Stark–Zeeman effect for parallel fields is considered and results for the states obeying |m| = l = n − 1 in the zero field limit are presented. Other problems that can be treated this way are discussed.
A method for the calculation of transition moments between electronic states of molecules using a different one‐electron basis set for each state
Authors: Theodorakopoulos G. , Petsalakis I. D. , Nicolaides C. A.
Published: December 2004

A state‐specific approach to the calculation of transition moments between molecular electronic states requires that the wavefunction for each state is expanded in its optimum one‐electron basis and that nonorthonormal basis techniques are used for the calculation of the transition moment integrals. A method has been developed for carrying out such nonorthonormal basis calculations, based on the corresponding orbitals transformation and appropriately defined density matrices, which may be used with configuration interaction (CI) wavefunctions. Further improvements of the method have resulted in a decrease in the time required for the calculations and thus allow its application with moderately large CI expansions for each state. Nonorthonormal basis calculations on transition moments in H2O have been carried out using the above method. The results are in agreement with those of large MRD‐CI calculations.
Iteration of the Schrödinger equation starting from Hartree–Fock wave functions
Authors: Avery John , Antonsen Frank
Published: December 2004

Methods are discussed for iterating the many‐particle Schrödinger equation starting from Hartree–Fock wave functions. It is shown that when the Hartree–Fock wave function is expressed as a linear combination of the appropriate basis functions in hyperspherical coordinates the hyperangular integrals needed for iteration can be evaluated analytically. It is also shown that the first‐iterated solutions contain terms corresponding to angular correlation.
A semiempirical investigation of interelectronic exchange coupling in bisected poly(1,4‐phenylene) polycation model systems
Authors: Lahti Paul M.
Published: December 2004

AM1 SCF‐MO‐CI computations find the bisected biphenyl dication to have nearly degenerate triplet and singlet states, with the lowest‐energy state being a quininoid singlet planar dication. The bisected perchlorobiphenyl dication favors a triplet ground state by a small amount (0.4‐1.9 kcal/mol), in qualitative agreement with recent experimental findings and with theoretical expectations that such an orthogonal open‐shell pi‐system should exhibit ferromagnetic exchange coupling. The higher oligomeric bisected para‐linked phenylenes polycations do not show an appreciable computational preference for a high‐spin multiplicity ground state either with or without perchlorine substitution. Chlorine substitution para to the 1,1′‐linkage may lend a unique stabilization to the biphenyl system, which is not available in higher oligomeric analogs of poly(1,4‐phenylene)s. The small magnitude of ferromagnetic exchange in these systems suggests that small geometric or substituent effects may confound experimental efforts to design polymeric ferromagnetic materials by this strategy. © 1992 John Wiley & Sons, Inc.
Intermediates of the borane reduction of some imidazolidines: An AM1 study
Authors: Bodor Nicholas , Prokai Laszlo
Published: December 2004

Amine(NB)‐aminoborane internal complexes and 1,3,2‐diazaborolidines were recently identified as intermediates of the borane reduction of imidazolidino[1,2‐d]dithiazepines. Theoretical Mo calculations were used to obtain the structural, conformational, and electronic properties and heats of formation of the boron compounds in the framework of the semiempirical AM1 approximation. Internal constraints in the bicyclic system were analyzed through comparisons with the calculated molecular geometries, electron distribution of monocyclic, and open‐chain models. The geometry of the five‐membered diazaborolidine systems becomes distorted upon building up the complex bicyclic structure, compared to the nearly planar monocycles. The weak coordinative nitrogen–boron bond (calculated bond order around 0.5) in the internal complexes exerts less conformational strains in the adjoining nine‐membered ring containing the disulfide than does the covalent NB bond in the corresponding 1,2,3‐diazaborolidine. Thus, the internal constraints of the bicyclic system is taken up by the five‐membered ring to a lesser degree in the 1,3,2diazaborolidine than in the internal complex. © 1992 John Wiley & Sons, Inc.
X–NO2 rotational energy barriers: Local density functional calculations
Authors: Habibollahzadeh Dariush , Murray Jane S. , Grice M. Edward , Politzer Peter
Published: December 2004

The X–NO2 rotational energy barriers of nitromethane, nitroethylene, nitrobenzene, and a group of nitramines have been computed using a local density functional (LDF) procedure, using ab initio Hartree–Fock (HF)‐optimized structures of the ground and rotational transition states. The results have been discussed in relation to HF and some correlated ab initio values and the available experimental data. Our LDF barriers are overall quite reasonable, in generally satisfactory agreement with the experimental and correlated ab initio results. © 1993 John Wiley & Sons, Inc.
Studies on the structural unit and suspending terminal groups in the quasi‐one‐dimensional periodic system
Authors: Zhu Jin , Yan Ji‐Min , Yan Da‐Yu
Published: December 2004

Quasi‐one‐dimensional periodic systems were investigated by the new proposed extrapolation method. The effect of the selection of the different structural units and their spin states on the periodic system was also studied. A quantum chemical calculation investigation of a 28 quasi‐one‐dimensional periodic system with MNDO (UHF) and EHMO/ASED–EHCO/ASED was undertaken. Quantum chemical calculation results with the MNDO (UHF) method showed that the proposed new method could be applied in the situation of the more precise semiempirical method. The selection of the different structural units and their spin states do not affect the extrapolated structural unit energy. The energy of suspending terminal group is generally higher for those with a higher bond order. The interaction energy between the suspending terminal groups generally decreases with the chain length. Comparison between the extrapolation results of EHMO/ASED and those from the crystal orbital calculation of EHCO/ASED indicates their equivalence, thus confirming the validity of the proposed method. © 1995 John Wiley & Sons, Inc.
A rapid generalized valence‐bond algorithm for semiempirical NDDO calculations
Authors: Cullen John M.
Published: December 2004

A recently developed algorithm based on the coupled cluster ansatz for the generalized valence‐bond perfect‐pairing model is adapted for the NDDO class of semiempirical methods. It allows for the calculation of the nondynamic electron correlation and executes as rapidly as the semiempirical molecular orbital method. To assess the interplay of the nondynamic and dynamic electron correlation vs. parameterization, preliminary results are presented for rotation about a double bond, dissociations about single bonds, and the relative stabilities of biradical isomers. © 1995 John Wiley & Sons, Inc.
Low energy positrons from metal surfaces
Authors: Dale J. M. , Hulett L. D. , Pendyala S.
Published: December 2004

There is reason to believe that slow positron spectroscopy will have value for surface analyses, but in order to develop practical methods it is necessary to devise monoenergetic sources of positrons that output usable intensities. This paper describes how this can be achieved by preparing certain metal surfaces to act as moderators for fast positrons from radioactive sources. After entering the moderator, the positrons are thermalized and a certain fraction are re‐emitted back into the vacuum. They can then be extracted by an electrostatic field and accelerated to any desired energy. Yields of low energy positrons were found to be generally large for certain metals having negative positron work functions (theoretically calculated). It is also necessary to minimize bulk defects, which act as positron traps. Tungsten and molybdenum are metals having negative work functions which can be easily prepared as effective moderators by simply heating in vacuum. This effects a cleaning by volatilizing oxides and anneals defects. The inertness of their surfaces towards oxidation allows them to maintain the negative work function effect which might otherwise be reduced by exposure to air and poor vacuum. These results have been utilized by the authors to design a monoenergetic positron gun to measure discrete energy losses in reflection spectra and threshold absorption effects. A Brandeis University group has used a tungsten moderator gun to make the first experimental measurements of low energy positron diffraction spectra.
Identification and quantification of Cu contamination on GaAs surfaces
Authors: Sykes D. E. , Chew A. , Hall D. D. , Crapper P. A. , Grant I. R. , Lamb M. S. M. , Lunn M. , Brozel M. R. , Davies P.
Published: December 2004

Secondary ion mass spectrometry has been used to identify the presence of Cu contamination on undoped semiinsulating GaAs wafer surfaces following polishing under certain conditions. The presence of a contaminating species on the wafer surface is indicated by the influence of pre‐etch treatments on electrical measurements performed on heat‐treated wafers, with and without Si implants. The identification of Cu as a contaminant is confirmed by photoluminescence measurements. With the appropriate wafer preparation process, the level of Cu contamination is below the SIMS detection limit of <1 × 1016 atoms cm−3.

In the SIMS analysis of the surface‐contaminated wafers, the Cu depth profile shape was dependent on the primary beam bombardment energy, suggesting a chemical segregation of Cu out of the altered layer, a redistribution that is known to occur in Si.

To quantify the surface concentration of Cu, GaAs wafers were deliberately contaminated with Cu, heat treated and analysed with glow discharge mass spectrometry and SIMS to provide a cross‐calibration.
Characterizing dryblending behavior of PVC resins
Authors: Changfoot J.
Published: December 2004

An important characteristic of a resin is the speed with which the polymer can be processed with the plasticizer in the plant, or its dryblending characteristics. The dryblending behavior of the polymer is dependent upon its microstructure and macrostructure. It is well known that some degree of porosity is required in order to obtain good dryblending properties; however, there are also other factors which affect the dryblending. Another factor, which is defined as the Swelling Index, is identified, and the use of this to help characterize dryblending behavior of different resins is discussed.
Zur Kenntnis der Kieselsäuren. VIII. Über Organisch substituierte Siliciumamide und deren Derivate
Authors: Schwarz Robert , Weigel Fritz
Published: December 2004

Umsetzung von Organochlorsilanen mit Ammoniak führt zu entsprechenden Organosiliciumamiden, die weiter zu Disilazanen kondensiert werden. Hierbei entstehen aus Diamiden auch Cyclosilazane. Bei Umsetzung mit Hexamethylendiamin wurde ein Triphenoxy‐Cyclohexylsilazin, bei Reaktion von Trialkylsiliciumamid mit Adipinsäurechlorid ein Triisopropoxy‐cyclotetramethylendiketosilazin dargestellt. Reaktionen rein organischer und siliciumorganischer Verbindungen gleichen Typs werden verglichen, der Unterschied wird diskutiert.
Über einige Verbindungen des Samariums vom NaCl‐Typ
Authors: Iandelli A.
Published: December 2004

Folgende Verbindungen sind hergestellt und röntgenographisch untersucht worden: SmN, SmP, SmAs, SmSb, SmBi, SmS, SmSe, SmTe und NdBi. Sie besitzen alle NaCl‐Struktur mit den Gitterkonstanten: 5,039 (SmN); 5,760 (SmP); 5,921 (SmAs); 6,271 (SmSb); 6,362 (SmBi); 5,970 (SmS); 6,200 (SmSe); 6,594 (SmTe); 6,424 Å (NdBi); alle ± 0,003 Å.

Der Verlauf der a0−Werte aller bekannten MX‐Verbindungen des La, Ce, Pr, Nd, Sm, Eu mit dem gleichen Nichtmetall kann mit einem Radienwertesystem für die einzelnen Elemente erklärt werden. Die Metallradien entsprechen denjenigen trivalenter Ionen, mit Ausnahme von SmS, SmSe, SmTe, EuS, EuSe, EuTe und CeN. Die genannten Sm‐ und Eu‐Verbindungen dürften Sm2+‐ bzw. Eu2+‐Ionen enthalten, in CeN dürfte ein gewisser Anteil von Ce4+‐Ionen vorhanden sein.
Über antimonorganische Verbindungen
Authors: Kolditz Lothar , Gitter Michael , Rösel Ekkehard
Published: December 2004

Es wird gezeigt, daß antimonorganische Verbindungen des Typs R3SbCl2, R3SbClOCH3 und R2SbCl3 (wobei R = CH3‐, C6H5‐, C6H5CH2‐) keine Neigung zur Aufspaltung in heteropolare Verbindungen besitzen. In polaren Lösungsmitteln haben sie keine elektrolytische Leitfähigkeit, in unpolaren Lösungsmitteln wird keine Aggregation festgestellt. Diese Verbindungen verhalten sich damit anders als Antimon(V)‐halogenide und Antimon(V)‐alkoxyhalogenide, die in unpolaren Lösungsmitteln aggregieren und in polaren Lösungsmitteln Ionen bilden. Verbindungen des Typs R3SbClOH und R2SbCl2OH wurden in fester Form nicht erhalten, Es entstehen die dimeren Verbindungen R3SbClOSbClR3 bzw. R2SbCl2OSbCl2R2 (R = C6H5‐, C6H5CH2‐).
Präparative und spektroskopische Untersuchungen an Tetrametaphosphimsäure und ihren Derivaten. III. Tetrametaphosphimsäure, ihr Hydrat und die Deuteriumverbindungen
Authors: Steger E. , Lunkwitz K.
Published: December 2004

Die Entwässerung von Tetrametaphosphimsäure‐Dihydrat wird in Beziehung zur Teilchengröße studiert. Deuteriumsubstitution erfolgt durch Austausch mit D2O. Die infrarotspektroskopische Untersuchung der verschiedenen Produkte erlaubt eine exakte Zuordnung der Frequenzen. Starke Wasserstoffbrücken vom Potentialverlauf mit 2 Minima sind zu bemerken. Die PO‐Bindungen sind schwächer als in den PO2‐Gruppen der Metaphosphate. Es besteht kein Grund, Hydroniumionen im Tetrametaphosphimsäure‐Dihydrat anzunehmen.
Die Dichte wäßriger Cd(NO3)2‐Lösungen bei 25°C
Authors: Fischer L.
Published: December 2004

Es werden die Ergebnisse von Dichtemessungen an wäßrigen Cd(NO3)2‐Lösungen bei 25°C im Konzentrationsbereich von etwa 0,005 bis 0,1 mol. 1−1 mitgeteilt und die daraus berechneten scheinbaren Molvolumina kurz diskutiert.
Zur Kenntnis des dreiwertigen Mangans: Verbindungen des Mangan(III)‐chlorids mit Aminen und einigen Äthern
Authors: Funk H. , Kreis H.
Published: December 2004

Mangan(III)‐chlorid liefert mit Aminen hauptsächlich 1:3‐Addukte, die feuchtigkeits‐empfindlich, aber bei Raumtemperatur beständig sind. Mit α,α′‐Dipyridyl und o,o′‐Phenanthrolin entstehen wasserlösliche Komplexe, in denen die Chloratome durch andere Anionen ersetzbar sind. — Die Äther‐Addukte sind temperaturempfindlich.

Die Umsetzung von Mangan(III)‐chlorid mit Acetylaceton führt zur Substitution von einem bzw. zwei Chloratomen durch das Diketon.
Die Kristallstruktur von Lithiummetaperiodat, LiIO4
Authors: Kraft Thorsten , Jansen Martin
Published: December 2004

Erstmals wurden Einkristalle von LiIO4 erhalten. Nach der Röntgenstrukturanalyse (monoklin, P21/n; a = 525,5(3), b = 851,1(4), c = 796,9(5) pm, β = 104,21(3)°; Z = 4; 2 148 unabhängige Reflexe, R = 0,024) wird Iod tetraedrisch und Lithium stark verzerrt trigonal‐bipyramidal von Sauerstoff koordiniert. Dabei sind jeweils zwei Lithium‐Sauerstoff‐Polyeder miteinander kantenverknüpft. Es besteht Isotypie zu LiAlH4. Die Struktur wird diskutiert und mit denen anderer Metaperiodate und Tetrahydridoaluminate verglichen.
Kristallstrukturbestimmungen an vier monoklinen Weberiten Na2MIIMIIIF7 (MII = Fe, Co; MIII = V, Cr)
Authors: Peschel B. , Molinier M. , Babel D.
Published: December 2004

Durch Festkörperreaktion der binären Fluoride wurden Einkristalle der folgenden Weberite dargestellt und röntgenographisch deren monokline Struktur bestimmt (Raumgruppe C2/c, Z = 16): Na2FeVF7 (a = 1 271,0(3), b = 742,9(1), c = 2 471,6(5) pm, β = 100,03(3)°; R1 = 0,043 (1 545 Reflexe); FeF = 203,8, VF = 193,0 pm); Na2FeCrF7 (a = 1 262,5(3), b = 739,1(1), c = 2 460,5(5) pm, β = 99,93(3)°; R1 = 0,029 (2 340); FeF = 203,6, CrF = 190,5 pm); Na2CoVF7 (a = 1 270,3(5), b = 739,1(3), c = 2 465,1(10) pm, β = 100,02(3)°; R1 = 0,028 (2 250); CoF = 201,6, VF = 193,6 pm); Na2CoCrF7 (a = 1 257,8(3), b = 733,5(1), c = 2 441,5(5) pm, β = 99,64(3)°; R1 = 0,030 (2 227); CoF = 201,2, CrF = 190,2 pm). Zu den genannten mittleren Abständen in den verzerrten [MF6]‐Oktaedern und zur Form der [NaF8]‐Koordination werden Einzelheiten mitgeteilt und diskutiert.
K3MnH5, das erste salzartige Manganhydrid
Authors: Bronger W. , Hasenberg S. , Auffermann G.
Published: December 2004

Die Synthese von K3MnH5 bzw. K3MnD5 gelingt durch Umsetzung von Kaliumhydrid (‐deuterid) mit Manganpulver bei einem Wasserstoffreaktionsdruck > 3000 bar und einer Temperatur von 875 K. Röntgenographische Untersuchungen an pulverförmigen Proben und elastische Neutronenbeugungsexperimente an der deuterierten Verbindung mit Hilfe des Flugzeitspektrometers LAD in Abhängigkeit von der Temperatur (5–600 K) führten zur vollständigen Strukturaufklärung.

Die Atomanordnung enthält neben isolierten [MnH4]2−‐Tetraedern Hydridionen, die ausschließlich von Kaliumionen koordiniert sind. Der Strukturaufbau entspricht dem im Cs3[CoCl4]Cl (Raumgruppe: 14/mcm, Z = 4). Die Temperaturabhängigkeit der magnetischen Suszeptibilitäten zeigt oberhalb von 50 K Curie‐Weiss‐Verhalten. Unterhalb 50 K treten offensichtlich antiferromagnetische Kopplungen auf.
Thia‐ und Selena‐arachno‐undecaboran 6,7‐μ‐(CH3E)B10H13 Kristallstruktur von arachno‐6,7‐μ‐(CH3Se)B10H13 Theoretische Untersuchungen der Molekülstrukturen und 11B‐NMR‐Verschiebungen von arachno‐6,7‐μ‐(CH3E)B10H13
Authors: Binder H. , Söylemez S. , Stöckle R. , Pfitzner A. , Hofmann M. , Schleyer P. v. R.
Published: December 2004

Bei der Reaktion zwischen B10H14 und (CH3)2S erfolgt unter H2‐Abspaltung eine zweifache Adduktbildung, die zu 6,9‐[(CH3)2S]2B10H12 führt. Die analoge Umsetzung zwischen B10H14 mit Disulfanen bzw. Diselenanen führte jedoch nicht zu den 6,9‐Dichalkogen‐verbrückten Derivaten. Bei der Umsetzung mit (CH3)2S2 findet selbst unter Refluxbedingungen keine Reaktion statt, wohl aber mit dem Trisulfan (CH3)2S3. Die Reaktion verläuft aber nicht unter H2‐Abspaltung. Vielmehr wird dabei ein Brücken‐H‐Atom durch eine CH3S‐Gruppe substituiert unter Bildung von (CH3S)B10H13 2. Im Gegensatz zu (CH3)2S2 findet aber mit (CH3)2Se2 ebenfalls eine Brücken‐H‐Substitution statt, wobei (CH3Se)B10H13 3 gebildet wird. 2 und 3 konnten in reiner Form isoliert und 11B‐NMR‐spektroskopisch charakterisiert werden. Von 3 wurde eine Röntgenstrukturanalyse durchgeführt (Raumgruppe P21/c) und von 2 und 3 die Molekülstrukturen auf MP2‐Niveau optimiert sowie 11B‐NMR‐ Verschiebungen mit IGLO‐SCF, GIAO‐SCF und GIAO‐B3LYP berechnet.
Synthese und Struktur eines zweikernigen Gadolinium(III)‐Komplexes: Magnetische Austauschwechselwirkungen in alkoxyverbrückten Komplexen der Lanthanoiden
Authors: Plass Winfried , Fries Guido
Published: December 2004

Synthesis and Structure of a Binuclear Gadolinium(III) Complex: Magnetic Exchange Interactions in Alkoxy Bridged Lanthanide Complexes

The Schiff Base ligand N‐salicylidene‐2‐(bis‐(2‐hydroxyethyl)amino)ethylamine (H3sabhea) reacts with Gd(NO3)3 · 6 H2O in methanol solution to yield the alkoxy bridged binuclear gadolinium(III) complex [{Gd(Hsabhea)(NO3)}2] · 2MeOH (1). 1 crystallizes in the monoclinic space group P21/c with a = 1014.8(2), b = 2059.2(4), c = 867.5(2) pm, β = 106.72(2)°, and Z = 2. The two gadolinium atoms are bridged by two alkoxide oxygen atoms with angles of 107.60(11)° at the oxygen bridgeheads and a GdGd separation of 376.43(7) pm. A variable‐temperature magnetic susceptibility study (2 to 280 K) of 1 revealed an antiferromagnetic coupling between the Gd(III) ions with J = −0.198 cm−1 (g = 1.975).
Beliefs about appropriate pain behavior: cross‐cultural and sex differences between Japanese and Euro‐Americans
Authors: Hobara Mieko
Published: December 2004

The Appropriate Pain Behavior Questionnaire (APBQ) was employed to examine the effects of the participants' sex and culture on their beliefs regarding gender‐appropriate pain behavior. The APBQ examines beliefs about the social acceptability to male and female participants of the behavioral and verbal expressions of pain by men and women (referents) in the presence of others [Nayak, S., 2000. Cross Cult Research 34, 135–151]. The participants were 18 male and 14 female Japanese, and 11 male and 21 female Euro‐Americans. There was a significant effect of sex: female participants considered pain behaviors more acceptable than male participants. There was a significant effect of culture: compared to both male and female Japanese, Euro‐American participants rated pain behaviors in both sexes to be more acceptable. There was also a significant effect of referent gender: for both sexes in both cultures, pain behaviors in women were rated as more acceptable than in men. Furthermore, a significant interaction was found between referent gender and sex of the participant: Male and female participants of both cultures were equally accepting of pain behaviors in women, but male participants were less accepting of pain behaviors in men than in women. There also was a significant interaction between referent gender and culture of the participant: Japanese participants considered pain behavior in both genders to be less acceptable than did Americans. The results are explained in terms of cultural traditions and social roles, and have clear implications for clinical treatment and diagnosis.
Yeast two‐hybrid screens imply that GGNBP1, GGNBP2 and OAZ3 are potential interaction partners of testicular germ cell‐specific protein GGN1
Authors: Zhang Jin , Wang Yan , Zhou Yu , Cao Zhiguo , Huang Peitang , Lu Baisong
Published: December 2004

Gametogenetin (Ggn) is a testicular germ cell‐specific gene specifically expressed from late pachytene spermatocytes through round spermatids. The function of gametogenetin protein 1 (GGN1) remains unknown. Here, we used the yeast two‐hybrid approach to look for more GGN1 interacting proteins. We found that gametogenetin binding protein 1 (GGNBP1), gametogenetin binding protein 2 (GGNBP2) and ornithine decarboxylase antizyme 3 (OAZ3) were potential GGN1 interaction partners. We determined the regions mediating the interactions and further showed the interactions between the proteins in mammalian cells by colocalization and coimmunoprecipitation experiments. Our work suggested that GGN1, GGNBP1, GGNBP2 and OAZ3 could be involved in a common process associated with spermatogenesis.
Plate tectonics, surface mineralogy, and the early evolution of life
Authors: Parnell J.
Published: December 2004

In addition to the accepted roles of plate tectonics in regulating planetary habitability through the composition of the atmosphere and temperature, and creating continents to enhance land-based evolution and biodiversity, it has a hitherto unexplored role in influencing surface mineralogy with possible implications for early evolution. Plate tectonics creates continents through the accretion of buoyant granitic crust. Erosion of the granites yields specific minerals including quartz, radioactive (uranium-, thorium-bearing) phases and phosphates, which could play a role in early evolution. Radioactive grains could help to concentrate carbon and increase its complexity through irradiation-induced polymerization at the prebiotic stage, and possibly influence mutation rates once life was established. Weathering of phosphate minerals was an important source of phosphorus for the biochemistry that is essential to life. Quartz-rich sands provide a translucent refuge for early photosynthesizers below the harmful effects of ultra-violet irradiation at the surface. Uranium is also important to the development of nuclear power in an advanced civilization. The mineralogy that engenders these processes is distinct from that to be expected on a planet without plate tectonics, where volcanogenic sediments would predominate, and further emphasizes the importance of plate tectonics to the evolution of life.
Cumulative prevalence of atopic eczema and related skin symptoms in a well‐baby clinic: a retrospective cohort study
Authors: Lehtonen Elina Pia‐Maria , Holmberg‐Marttila Doris , Kaila Minna
Published: December 2004

The aim of the study was to assess the frequency and treatment policy of atopic eczema (AE) and related skin symptoms including rash, redness, dryness and itch in 0‐ to 5‐year‐old children. Health records of 320 children born in 1994 were systematically studied. The main results were that 77% of children suffered from skin symptoms during their first 5 years while the cumulative prevalence of AE was 16%, and 11% of children with skin symptoms were referred to a specialist. AE and related skin symptoms were common in the first 5 years of life, and were mostly temporary and responsive to topical treatment. Well‐baby clinics play a key role in the treatment of skin‐symptomatic children.
Differential expression of seven α‐expansin genes during growth and ripening of pear fruit
Authors: Hiwasa Kyoko , Rose Jocelyn K. C. , Nakano Ryohei , Inaba Akitsugu , Kubo Yasutaka
Published: December 2004

Seven cDNAs, designated PcExp1 to PcExp7, encoding expansin homologues, were isolated from mature pear fruit and their expression profiles were investigated in ripening fruit and other tissues, and in response to ethylene. Accumulation of PcExp2, ‐3, ‐5 and ‐6 mRNA increased markedly with fruit softening and then declined at the over‐ripe stage. Treatment of fruit at an early ripening stage with 1‐methylcyclopropene (MCP), an inhibitor of ethylene action, suppressed ethylene biosynthesis, fruit softening and the accumulation of the expansin mRNAs. Conversely, propylene treatment at the preclimacteric stage induced accumulation of the same four expansin genes, as well as ethylene production and fruit softening. The expression patterns correlated with alteration in the rate and extent of fruit softening. The abundance of PcExp1 mRNA increased at the late expanding phase of fruit development and further increased during ripening, whereas PcExp4 mRNA levels were constant throughout fruit growth and ripening. The MCP and propylene treatments had little effect on PcExp1 and PcExp4 expression. PcExp7 was expressed in young but not mature fruit. PcExp4 and PcExp6 mRNA was also detected in flowers. The accumulation of PcExp4, ‐5, ‐6 and ‐7 mRNA was more abundant in young growing tissues, but not in fully expanded tissues, suggesting roles for these genes in cell expansion. These results demonstrate that characteristically, multiple expansin genes show differential expression and hormonal regulation during pear fruit development and at least six expansins show overlapping expression during ripening.
Mitochondrial oxidative phosphorylation is required for ammonium assimilation in light in a marine diatom
Authors: Rees T. Alwyn V.
Published: December 2004

Ammonium assimilation in plants occurs via the glutamine synthetase (GS, EC 6.3.1.2)/glutamine 2‐oxoglutarate aminotransferase (GOGAT, EC 1.4.1.13 + 1.4.1.14 + 1.4.7.1) pathway. Rates of in vivo ammonium assimilation were measured in the marine diatom Phaeodactylum tricornutum by a recently developed technique that uses the protonophore carbonyl cyanide m‐chlorophenylhydrazone to release unassimilated ammonium from the cells. In nitrogen‐replete cells of P. tricornutum, there was a poor relationship between uptake and in vivo assimilation of ammonium, with the rate of uptake decreasing and the rate of assimilation increasing with time in the presence of ammonium. Ammonium uptake and assimilation were markedly light dependent, with assimilation inhibited by 77% in darkness. Oligomycin (5 µg ml−1), an inhibitor of the mitochondrial ATPase, had no effect on the rate of photosynthesis, the maximum endogenous ammonium pool or GS activity in Phaeodactylum, but inhibited respiration by 24–27%. In the light, oligomycin inhibited ammonium assimilation by 55–70% and growth rate by 52%. One possible explanation for these results, namely that mitochondrial ATP is required to sustain activity of the cytosolic isoform of GS, is discussed.
Membrane‐associated protein kinase activities in developing apple fruit
Authors: Duan Chang‐Qing , Shen Yuan‐Yue , Liang Xiao‐E , Zhang Da‐Peng
Published: December 2004

Fruit development is a process involving various signals and gene expression. Protein phosphorylation catalysed by protein kinases is known to play a key role in eukaryotic cell signalling and so may be involved in the regulation of fruit development. Using the method of exogenous substrate phosphorylation, the activity of calcium‐dependent and calmodulin‐independent protein kinase (CDPK) that was stimulated by phosphatidylserine, and the myelin basic protein (MBP)‐phosphorylating activity that could be due to a calcium‐independent mitogen‐activated protein kinase‐like (MAPK‐like) activity in the developing apple fruits were identified. The CDPK activity was shown to be predominantly localized in the plasma membrane, whereas in the presence of phosphatidylserine, the high activity of CDPK was detected in both plasma membrane and endomembranes. The MAPK‐like activity was predominantly associated with endomembranes. The assays of bivalent cation requirement showed that Mn2+ could replace Mg2+ in the incubation system for the protein kinase activities and stimulate CDPK activity more than Mg2+. Heat treatment abolished CDPK but stimulated MAPK‐like activity. The activities of the phosphatidylserine‐stimulated CDPK and of the MAPK‐like were fruit developmental stage‐specific with higher activities of both enzymes in the early and middle developmental stages in comparison with the late developmental stage. These data suggest that the detected protein kinases may play an important role in the fruit development.
Recruitment in a Mediterranean annual plant community: seed bank, emergence, litter, and intra‐ and inter‐specific interactions
Authors: Rebollo S. , Pérez‐Camacho L. , García‐de Juan M. T. , Rey Benayas J. M. , Gómez‐Sal A.
Published: December 2004

A small‐scale field study was conducted to explain seedling emergence and recruitment of reproductive individuals in a four‐year‐old Mediterranean annual plant community. The analyzed levels were populations, functional types, and total number of individuals in the community. We hypothesized that the number of germinable seeds positively affects the number of emerged seedlings, which positively affects the number of reproductive individuals. We hypothesized as well that litter mass, biomass of established adults, and number of non‐conspecific emerged seedlings negatively affect the numbers of emerged seedlings and reproductive individuals. The results supported our multivariate causal explanation of plant recruitment, although concordances with the initial hypotheses were more frequent at the community level. The effect of the number of germinable seeds on the number of emerged seedlings was found to be robust only at the community level. At the population level, this relationship did not have a consistent tendency and depended on species identity and range of seed density experienced. Litter had negative effects on total number of individuals in the community, and usually non‐significant effects at the population level. Litter effects were found to be inversely related to seed mass, and sharper cotyledons did not improve seedling emergence likely by favoring litter mat penetration. Interactions among plant species appeared not to have any effect on seedling emergence and survival, and had positive effects on certain populations. Biomass of established adult plants exerted no influence on seedling emergence and survival, probably due to their low abundance in this community during the germination period. Results permitted the inference of the main stages in the recruitment process and causal factors. They provided evidence for the greater importance of germination and emergence in comparison with seedling survival to insure reproductive recruitment in this community.
A comment on Hubbell's zero‐sum ecological drift model
Authors: Ricklefs Robert E.
Published: December 2004

In Hubbell's model of zero‐sum ecological drift, loss of species from communities by stochastic change in population size is balanced by the production of new species by processes analogous to mutation or to the fission of populations. Large regional metacommunities contain so many individuals that species are lost slowly and infrequent speciation events can maintain high diversity. However, validation of Hubbell's model requires that community size, diversity, and species life spans match up, and this is shown to be a problem with both the mutation and fission mechanisms of speciation. In the first case, most species are rare and ephemeral and would fail to be recognized by traditional taxonomic practices. In the second case, species life spans are so long that diversity builds to unrealistic levels. Thus, the problem confronting community drift probably is not the maintenance of diversity but rather its control, requiring such mechanisms as environmental change or occasional evolution of competitively superior species that sweep the metacommunity. Testing the community drift model will require close attention to community size and species life spans.
Altered conditioned fear behavior in glutamate decarboxylase 65 null mutant mice
Authors: Stork O. , Yamanaka H. , Stork S. , Kume N. , Obata K.
Published: December 2004

We investigated the involvement of the 65 kDa isoform of glutamic acid decarboxylase (GAD65) and GAD65‐mediated γ‐aminobutyric acid (GABA) synthesis in the formation and expression of Pavlovian fear memory. To this end, behavioral, endocrine and autonomic parameters were examined during conditioned fear retrieval of mice with targeted ablation of the GAD65 gene (GAD65–/– mice). These mutant mice were found to display specific fear behavior (freezing, escape), as well as autonomic (increased defecation) and endocrine activation (increased plasma corticosterone) during fear memory retrieval. However, freezing was reduced and flight and escape behavior were increased in GAD65–/– mice compared to their wild type and heterozygous littermates, while corticosterone levels and defecation rates did not differ between genotypes. Active defensive behavior of GAD65–/– mice was observed during both auditory cued and contextual retrieval of fear memory, as well as immediately after conditioning. These data indicate a selectively altered behavioral fear response in GAD65–/– mice, most likely due to deficits in threat estimation or the elicitation of appropriate conditioned fear behavior, and suggest that GAD65 is a genetic determinant of conditioned fear behavior. GAD65–/– mice provide a valuable tool to further dissect the GABAergic mechanisms involved in fear and anxiety and to model GABA‐related neurological and psychiatric disorders.
Prepulse inhibition of acoustic startle in aromatase knock‐out mice: effects of age and gender
Authors: Van Den Buuse M. , Simpson E. R. , Jones M. E. E.
Published: December 2004

Estrogen has been suggested to play a neuromodulatory and neuroprotective role on the brain dopamine system. We used aromatase knockout (ArKO) mice that lack a functional aromatase enzyme and are unable to convert testosterone into estrogen, and assessed prepulse inhibition of acoustic startle, locomotor hyperactivity to amphetamine treatment and rotarod performance. Mice were tested at either 1 month, 4–5 months or 12–18 months of age. In male, but not female ArKO mice, there was an age‐related reduction of prepulse inhibition. The 12–18 months old male ArKO mice also showed significantly greater amphetamine‐induced hyperactivity. Mice heterozygous for the mutation showed no deficits or were in‐between wildtype mice and ArKO mice. We postulate that these data indicate a neuroprotective role of estrogen, particularly in male mice, on ageing of brain mechanisms involved in prepulse inhibition and locomotor activity regulation. It is likely that these brain mechanisms are or include dopaminergic activity.
Altered matrix polysaccharides in cell walls of pocket galls formed by an aphid on Distylium racemosum leaves
Authors: KONNO H. , NAKATO T. , TSUMUKI H.
Published: December 2004

The present work reports the results of a study on the isolation and characterization of matrix polysaccharides in the cell walls of galls formed by an aphid (Neothoracaphis yanonis) on Distylium racemosum leaves. Cell walls were isolated from both healthy Distylium leaf and gall tissues and then extracted sequentially with cyclohexane‐trans‐1,2‐diaminetetra‐acetate (CDTA), Na2CO3, 1 m KOH, and 4 m KOH. The amount of pectin solubilized from gall cell walls was approximately 2.6‐fold higher than the pectin solubilized from leaf cell walls, whereas the amount of hemicellulose solubilized from gall cell walls was 1.4‐fold higher than that from normal leaf cell walls. When the polysaccharides were fractionated by anion‐exchange chromatography, considerable increases in arabinose and galactose were observed in CDTA‐soluble pectic polymer (fraction PI‐1) from gall cell walls, whereas the gall cell walls had less xylose in 1 m KOH‐soluble hemicellulosic polymers (fractions HI‐2, HI‐3, and HI‐4) than did the cell walls from the healthy leaf. The hemicellulosic polymers of the gall cell walls exhibited distinctly different patterns of molecular mass, compared with the healthy leaf cell walls. These results suggest that an extensive change occurs in the matrix polysaccharide structure of the cell walls of Distylium galls formed by an aphid. In addition, many glycosylhydrolase activities were detected in the protein fraction solubilized with strong saline solution from the gall cell walls, and the activities of β‐galactosidase, β‐xylosidase and α‐l‐arabinofuranosidase were considerably increased under gall formation.
Bone mineral metabolism and histomorphometry in rats with cholestatic liver disease
Authors: Ackerman Zvi , Weinreb Miron , Amir Gail , Pollak Rivka D
Published: December 2004

Background: The etiology of osteopenia in cholestatic liver disease is uncertain. An animal model is needed in order to study the efficacy of therapeutic agents.

Aims: In order to characterise the bone disease in rats with cholestatic liver disease.

Methods: Four‐month old male Sprague–Dawley bile duct‐ligated (BDL) and sham‐operated (SO) rats were studied. Twenty‐eight days after surgery serum osteocalcin, a bone‐formation marker, urinary deoxypyridinoline (DPD) cross‐links, a resorption marker, and 25‐hydroxyvitamin D3 were determined. Static and dynamic (tetracycline‐based) histomorphometric analysis was performed on femurs and tibiae.

Results: All BDL rats developed biliary cirrhosis. Bile duct‐ligated rats had lower bone mass, reflected in statistically significantly 13.5% lower femoral dry‐weight, 16% lower femoral ash‐weight, 42.7% lower tibial cancellous bone area and 19% lower trabecular thickness, compared with SO rats. Bile duct‐ligated rats exhibited decreased bone formation manifested by statistically significantly 70% lower tetracycline double‐labelling, 40% lower mineralising surface, 51% lower bone‐formation rate and 47% lower osteocalcin compared with SO rats. Deoxypyridinoline levels were 20% lower in BDL rats. Bile duct‐ligated rats had 52% lower serum 25‐hydroxyvitamin D3 level, but no significant increase in cortical osteoid area.

Conclusions: Bile duct‐ligated rats develop osteopenia characterised by low bone‐formation rate, and can be used for studying therapeutic agents for patients with cholestatic liver disease displaying similar bone changes.
Generation means analysis of resistance to peanut bud necrosis caused by peanut bud necrosis tospovirus in peanut
Authors: Pensuk V. , Jogloy S. , Wongkaew S. , Patanothai A.
Published: December 2004

This study was conducted to evaluate the types of gene action governing the inheritance of resistance to peanut bud necrosis disease (PBND) in populations derived from three crosses involving two resistant (ICGV 86388 and IC 10) and one susceptible (KK 60–1) peanut lines. Populations were composed of P1 P2, F1 F2, BC11, BC12, BC11S and BC12S. These populations were evaluated for PBND incidence in a farmer's field in Kalasin province in north‐east Thailand, where PBND is a recurring problem. Results showed variations between crosses in the relative contributions of different types of gene effect. The results indicate that multiple genes control the PBND resistance trait, and that the two resistant lines differ in some of these genes. As non‐additive gene effects are important in all three crosses, selection for low PBND incidence in these crosses would be more effective in later generations.
A novel foraging mode in snakes: browsing by the sea snake Emydocephalus annulatus (Serpentes, Hydrophiidae)
Authors: Shine R. , Bonnet X. , Elphick M. J. , Barrott E. G.
Published: December 2004

Ecologists often ascribe considerable importance to traits that are widespread within a specific lineage but rarely seen in other kinds of organisms. Unfortunately, such hypotheses cannot be tested robustly unless there is variation in expression of the trait within that lineage; such ‘exceptions to the rule’ provide opportunities to falsify predictions about putative functional correlates of the focal trait.

Research on snake foraging has emphasized species that feed infrequently and take large prey, often from ambush positions, but these characteristics do not apply to all snakes.

Movement patterns and feeding rates of free‐ranging Turtle‐Headed Sea Snakes Emydocephalus annulatus (Krefft 1869) were quantified in coral reefs of New Caledonia. These snakes forage by moving slowly (<2 m min−1) but consistently across the substrate as they investigate crevices and burrows for fish nests. The snakes feed frequently (sometimes, several times per hour) on large numbers of very small (1 × 0·5 mm2) eggs. Snakes weighed more than one hundred thousand times as much as the prey items (eggs) they consumed, in contrast to high relative prey masses often reported for other snake species.

Field experiments in which snakes were exposed to a variety of stimuli indicate that these animals locate their prey by scent rather than visual cues.

The foraging mode of Emydocephalus (slow continuous movement, with frequent ingestion of small, immobile, defenceless food items) is more similar to that of herbivorous browsing mammals than to that of most macrostomate snakes.

In support of published hypotheses, Emydocephalus differ from most other snakes in traits predicted to be functionally associated with ingestion of large prey.
Does Public Health Nurse Home Visitation Make a Difference in the Health Outcomes of Pregnant Clients and Their Offspring?
Authors: Fetrick Ann , Christensen Mary , Mitchell Carol
Published: December 2004

Abstract  Public health nurses (PHNs) at Lincoln‐Lancaster County Health Department have used the Care Pathway tool to track client progress. Conceptually similar to critical pathways used in hospital settings, the Care Pathway is used by the PHN to document milestones of progress by trimester of pregnancy. Data for this research was gathered from chart review of 55 prenatal clients. Study results demonstrate that subjects who had from five to nine home visits by a PHN during pregnancy showed a higher average hemoglobin for the mothers and a higher average birthweight for the babies than those visited four or fewer times. None of the low birthweight babies was born to mothers in the “more visits” category. Furthermore, more breastfeeding was recorded for those who had received more PHN visits. This documentation enabled us to describe better the referent population and to begin to estimate the effect of PHN home visitation on the health outcomes of clients. In essence, we addressed the questions: (1) “Does PHN home visitation make a difference in health outcomes of clients and their families?” and (2) “If so, how can effects be measured?”
Plasma antioxidative activity during atorvastatin and fluvastatin therapy used in coronary heart disease primary prevention
Authors: Kowalski Jan , Pawlicki Lucjan , Grycewicz Joanna , Błaszczyk Jan , Irzmański Robert , Cegliński Tomasz , Kowalczyk Edward
Published: December 2004

We estimated the effect of atorvastatin and fluvastatin on plasma antioxidative activity used in coronary heart disease (CHD) primary prevention. Anti‐oxidative activity of blood plasma was determined by Bartosz et al. method [Curr. Top. Biophys. (1998)22:11–13], based on reduction of preformed cation radical of 2,2,azinobis(3‐ethylbenzothiazoline‐6‐sulphonic acid) by blood plasma. The study comprised 35 patients with CHD risk who were randomly divided into two groups. The atorvastatin group comprised 17 patients who were administered the drug orally in a daily dose of 10 mg and the fluvastatin group consisted of 18 patients on an oral dose of 40 mg once daily. The control group comprised 12 healthy subjects with no drug administration. Blood samples were collected from cubital vein before and after 6‐week therapy. Significantly (P < 0.05) increased – in comparison with the initial values – antioxidative activity of blood plasma was found in atorvastatin and fluvastatin groups after 6‐week therapy. Moreover, the increase in antioxidative plasma activity in atorvastatin group was significantly higher in comparison with the fluvastatin group. The results of our study have demonstrated that atorvastatin and fluvastatin have an additional mechanism independent of the effect on cholesterol concentration. Thus, we presume that administration of these statins in CHD risk patients may have a beneficial effect.