bluuebunny/crossref_metadata_2025 huggingface dataset:
The PPP model of alternant cyclic polyenes with modified boundary conditions
Authors: Bendazzoli G. L. , Evangelisti S.
Published: January 2005

The extension of the PPP Hamiltonian for alternant cyclic polyenes to noninteger values of the pseudomomentum by imposing modified boundary conditions is discussed in detail. It is shown that a computer program for periodic boundary conditions can be easily adapted to the new boundary conditions. Full CI computations are carried out for some low‐lying states of the PPP model of altemant cyclic polyenes (CH)N, (N even) at half‐filling. The energy values obtained by using periodic (Bloch) and antiperiodic (Möbius) orbitals are used to perform energy extrapolations for N → ∞. © 1995 John Wiley & Sons, Inc.
Theoretical studies on the structure and electronic properties of 3‐isothiazolones
Authors: Morley John O. , Charlton Michael H.
Published: January 2005

The structure of 4,5‐benzo‐3‐isothiazolone and 5‐phenyl‐2‐(E)‐styryl‐3‐isothiazolone have been calculated both at the semiempirical AM1 level and by using the ab initio 4‐31G basis set. Neither method gives a satisfactory account of the bond lengths and angle at the sulfur atom in comparison with crystallographic data, but the inclusion of polarization functions on the sulfur atom alone gives a marked improvement in the theoretical results. The conformations, structure, and electronic properties of a series of other antifungal 3‐isothiazolones have been calculated by the same method. Although structural effects do not appear to play an important role in the mechanism of the inhibition of fungi by the 3‐isothiazolones described here, the electronic properties calculated in terms of the atomic charge at sulfur and the LUMO energy appear to relate to their known reactivity with nucleophiles and their observed biological activity. © 1995 John Wiley & Sons, Inc.
Searching for transition states: The line–then–plane (LTP) approach
Authors: Cárdenas‐Lailhacar Cristián , Zerner Michael C.
Published: January 2005

A procedure for finding transition states ( TS) that does not require the evaluation of the second derivatives during the search is proposed. The procedure is based on connecting a series of points representing products Pi and reactants Ri and taking conservative steps along the difference vector from Pi toward Ri and from Ri toward Pi until the two points coalesce. Although the points Po and Ro represent the product and reactant specifically, other Pi and Ri are determined by minimization in hyperplanes perpendicular to Pi −1 and Ri−1. We apply this technique to six well‐known potential functions and compare these results with those obtained from other well‐known procedures. © 1995 John Wiley & Sons, Inc.
Ab initio energies and tunneling lifetimes of the doubly charged AH2+ (A = Mg—Ar) diatomics
Authors: Nefedova V. V. , Boldyrev A. I. , Simons J.
Published: January 2005

Potential energy curves for the ground and low‐lying excited states of the AH2+ (A = Mg—Ar) dications have been calculated using high‐level ab initio methods with large atomic orbital basis sets. Quasi‐bound potential energy curves with local minima and deprotonation barriers have been found for most of the dications studied. The energies, tunneling lifetimes, and widths of the quasi‐bound states have been calculated by numerical solution of the radial Schrodinger equation using the Numeov method. All these dications except ArH2+ have low‐lying states which support quasi‐bound vibrational states. The ArH2+ dication has a 2∏i potential energy curve with a minimum so shallow that it does not support any quasi‐bound vibrational states. Results of our calculations are compared with previous ab initio calculations and available experimental data. © 1995 John Wiley & Sons, Inc.
Acidity of first‐ and second‐row hydrides: Effects of electronegativity and hardness
Authors: De Proft F. , Langenaeker W. , Geerlings P.
Published: January 2005

A study is made on the influence of the electronegativity and hardness of a group X on the gas‐phase acidities of the first‐ and second‐row hydrides HX. It is shown that these two density functional theory (DFT)‐based global properties are sufficient for the correct description of the gas‐phase acidity sequences, the group hardness being the more important factor and describing the influence of polarizability effects in the charged forms of the acid–base equilibrium. Various calculated properties of the traditional quantum chemical type (Mulliken charges and the MEP) and DFT‐based (local softness), associated with the neutral form of the acid, were found to contain a certain periodicity in their description of the gas‐phases acidities. The gas‐phase acidities (Δ Hacid and ΔGacid values) were also obtained theoretically via quantum statistical thermodynamical calculations at the Hartree–Fock level with the 6‐31 + G* basis set; these calculated acidities were in fair agreement with the experimental ones. © 1995 John Wiley & Sons, Inc.
Theoretical energies of representative carbon–carbon bonds
Authors: Barone Vincenzo , Fliszár Sándor
Published: January 2005

A bond‐energy formula deduced by means of the Hellmann–Feynman theorem is applied to selected simple hydrocarbons. The required potentials at the nuclei are calculated with the help of large basis‐set expansions including polarization functions. The carbon–carbon bond energy of ethane is evaluated at ∼ 70 kcal mol−1. TheCCbond energies of ethane, ethylene, acetylene, benzene, and cyclopropane are approximately in a ratio of 1: 2.0: 3.0: 1.65 1.0. Limitations and possible improvements in future applications of this energy formula are discussed. © 1995 John Wiley & Sons, Inc.
An atomic interaction energy approach to the reactivity of the aromatic ring toward electrophilic attack
Authors: Yu Zhong‐Heng
Published: January 2005

A procedure of constructing a complete fragment orbital basis set is described in detail. It provides a complete fragment orbital basis for PMO analysis of the atomic interaction energy. Rt values, a ratio of the bonded atomic interaction energy to the nonbonded interaction energy arising from the peripheral atoms of the aromatic rings, indicate a decrease in the reactivity of the aromatic ring toward electrophilic attack in the sequence: pyrrole > imidazole > furan > pyrazine > pyrimidine > aniline > benzene > pyridine > p‐acylaniline > p‐cyanoaniline > p‐nitroaniline > m‐cyanoaniline. © 1995 John Wiley & Sons, Inc.
Über die Bildung von Hyponitrit durch Disproportionierung des Hydroxylamins
Authors: Nast R. , Föppl I.
Published: January 2005

Es wird eine neue Bildungsweise für Hyponitrite beschrieben, die primär auf eine Disproportionierung des Hydroxylamins in NH3 und HNO zurückgeht, wobei Nitroxyl sich teilweise zu Hyponitrit dimerisiert. Es wird ferner gezeigt, daß die Entstehung aller wesentlichen Zersetzungsprodukte des Hydroxylamins auf Folgereaktionen primär gebildeten Nitroxyls zurückzuführen sind.
Beitrag zur Kristallchemie komplexer Wismutchalkogenverbindungen
Authors: Gattow G. , Zemann J.
Published: January 2005

LiBiS2, NaBiSe2 und KBiSe2 kristallisieren im NaCl‐Typ mit statistischer Alkali‐ und Wismutverteilung. Die Gitterkonstanten sind: LiBiS2: a = 5,603 Å, NaBiSe2: a = 5,852 Å, KBiSe2: a = 5,922 Å.
Wasserstoffverbindungen von Schwermetallen. II. Zur Darstellung von Schwermetall‐Wasserstoff‐Verbindungen nach der Methode von SCHLENK und WEICHSELFELDER
Authors: Sarry Brigitte
Published: January 2005

Es werden die Bedingungen untersucht, unter denen eine vollständige Umsetzung von Schwermetallchloriden mit Phenylmagnesiumbromid und Wasserstoff möglich ist, und die Abweichungen der eigenen Beobachtungen von den Ergebnissen von SCHLENK und WEICHSELFELDER begründet.
Über Metallcarbonyle. 68. Die Basenreaktion des Chromhexacarbonyls
Authors: Hieber W. , Abeck W. , Platzer H. K.
Published: January 2005

Die Basenreaktion des Chromhexacarbonyls führt unter Verwendung alkoholischer Alkalilauge bei höherer Temperatur zur Entstehung von 1 Mol Carbonat pro Metallatom (I), jedoch wird bereits im alkalischen System allmählich 1 Mol Wasserstoff pro Chromatom frei (II). Die Reaktion läßt sich in Anlehnung an die Basenreaktion des Fe(CO)5 durch das intermediäre Auftreten labiler Carbonylchromat‐Anionen erklären:

equation image

Unter weiterem Abbau von Kohlenoxyd, das mit der alkoholischen Lauge unter Formiatbildung reagiert, entsteht gelbes Hydroxo‐diaquo‐tricarbonyl‐chromat (0) (III), das im allgemeinen im Gleichgewicht mit dem roten Triaquokomplex vorliegt:

equation image
.
Über fluorhaltige Verbindungen der Elemente der V. Hauptgruppe. I. Das [AsCl4]+[AsF6]−
Authors: Kolditz Lothar
Published: January 2005

Durch Einleiten von Chlor in Arsentrifluorid bei 0° C entsteht eine kristalline Substanz mit einem Atom‐Verhältnis von As:Cl:F = 1:2:3. Sie ist in Arsentrifluorid gut löslich und fällt bei Überschuß an AsF3 erst nach längerer Zeit aus, wenn die Sättigungskonzentration der sich langsam bildenden Verbindung in AsF3 als Lösungsmittel erreicht ist. In der neuen Verbindung ist das Fluor so fest an Arsen gebunden, daß zur quantitativen Bestimmung ein Aufschluß mit metallischem Natrium erforderlich ist. Es wird chemisch bewiesen, daß der Substanz die Struktur [AsCl4]+[AsF6]− zukommt. In Arsentrifluorid zeigt [AsCl4]+[AsF6]− elektrolytische Leitfähigkeit.
Beitrag zur Kenntnis des Silber(II)‐oxyds
Authors: Schwab Georg‐Maria , Hartmann Guido
Published: January 2005

Durch DEBYE‐SCHERRER‐Aufnahmen wie durch Messung der katalytischen Wirksamkeit und ihrer Temperaturabhängigkeit gegenüber dem Ozonzerfall wird gezeigt, daß die durch Oxydation von Silber und Silber(I)‐oxyd, durch Zersetzung von Ag7NO11 und durch Peroxydisulfat‐oxydation von Ag+ erhältlichen Oxyde identisch mit Silber(II)‐oxyd sind.
Zur Kenntnis der Chemie der Metallcarbonyle in flüssigem Ammoniak. I. Über die Reaktionen der Carbonyle des Eisens und Kobalts mit Alkalimetallen
Authors: Behrens H. , Weber R.
Published: January 2005

Die monomeren und mehrkernigen reinen Carbonyle des Eisens und Kobalts lassen sich durch Lösungen von Alkalimetallen in flüssigem Ammoniak leicht zu den betreffenden Carbonylmetallaten reduzieren. Die Reaktionen werden durch Bestimmung der verbrauchten Alkalimetallmengen, der gebildeten Carbonylmetallate sowie der bei den Reaktionen freiwerdenden Gase quantitativ untersucht.
Titanium salts of mono‐carboxylic acids. I. Attempted Preparation of Titanium Tetra‐Soaps
Authors: Pande K. C. , Mehrotra R. C.
Published: January 2005

With a view to prepare the tetra‐soaps of titanium, the reaction between titanium alkoxides and excess of various fatty acids has been studied in refluxing benzene. The alcohol produced was removed azeotropically with the solvent. However, all the four alkoxy groups per titanium atom could not be replaced in any of the experiments. Even on carrying out the reaction in a higher boiling solvent like toluene, similar results were obtained and only 3 moles of alcohol per mole of the alkoxide could be azeotropically distilled out. It has been shown that the fourth alkoxy group is held in such a manner that it cannot be displaced even on refluxing the reaction product with higher alcohols or water. On heating the product to about 200° under reduced pressure, the excess fatty acid which distilled out has been shown to be mixed with some ester and the residue was found to be a decomposed titanium soap of the type TiOx(OOCR)4−2x with the value of ‘x’ nearly 0.5. These observations have been explained either by the steric hindrance to the entry of the fourth acid group or by the occurrence of other side reactions with the formation of organic ester.
Magnetochemische Untersuchungen an Metallcarbonylkomplexen
Authors: Hieber W. , Floss J. G.
Published: January 2005

Für eine Reihe von substituierten Metallcarbonylverbindungen, namentlich der Edelmetalle Ruthenium und Rhodium, konnte auf Grund der magnetischen Eigenschaften ihre Konstitution als Molekülkomplexe bestätigt und ihre Bindungsfunktionen festgelegt werden.

Insbesondere war es ferner möglich, die salzartige Konstitution von Produkten der Reaktion von Eisen‐ und Mangancarbonylen mit N‐ und O‐Basen, die in letzter Zeit mehrfach diskutiert wurden, eindeutig zu beweisen. Die Anionen [Fe(CO)4]2−, [Fe2(CO)8]2−, [Fe3(CO)11]2−, [Fe4(CO)13]2−, sowie das [Mn(CO)5]− erweisen sich als diamagnetisch, während ihre Verbindungen mit paramagnetischen Komplexkationen das bekannte Moment derselben zeigen.

Ebenso wurde bei CO‐haltigen Rheniumverbindungen deren salzartige Struktur mit CO‐haltigem Kation bestätigt.
Über Lithium‐ und Natriumuranat(V)
Authors: Rüdorff W. , Leutner H.
Published: January 2005

Bei der Umsetzung von Lithium‐ bzw. Natriummonouranat(VI) mit UO2 entstehen die beständigen Uranate (V), LiUO3 bzw. NaUO3. Die entsprechende Kaliumverbindung konnte nicht erhalten werden.
Über Nickel–Zink‐Mischoxalatkontakte
Authors: Welker J.
Published: January 2005

Durch Zersetzung von Nickeloxalat–Zinkoxalat‐Mischkristallen im Wasserstoffstrom werden Katalysatoren erhalten, die sich bei Reaktionen in der Gasphase durch hohe Aktivität auszeichnen. Die Hydrierung von Aceton und Benzol verläuft schon bei Temperaturen weit unter 100° vollständig. Bei hohem Zinkgehalt sind die Katalysatoren zur verlustlosen Dehydrierung von Naphthenen im Wasserstoffstrom vorzüglich geeignet. Da Paraffine nicht in nennenswertem Maße der destruktiven Hydrierung unterliegen, ist eine Dehydrierung von naphthenhaltigen Benzinfraktionen möglich.
Zur Kenntnis der Alkalizirkonate
Authors: Lehmann Hans‐Albert , Erzberger Peter
Published: January 2005

Als einzige Verbindung im System Na2OZrO2 wird das Na2ZrO3 bestätigt. Im System K2OZrO2 existieren drei röntgenographisch unterscheidbare Formen des K2Zr2O5 (Form I K2O/ZrO2= 0,5:1;II<0,5:1;III>0,5:1). Die stabile aller drei Formen ist II. Die Hydrolyse des K2Zr2O5 führt in der Kälte nicht zu vollständiger Zersetzung, sondern ist beendet, wenn etwa ¼ des Gehaltes an Kalium gelöst ist. Beim Erhitzen derartiger Hydrolyseprodukte entsteht unter Freiwerden von ZrO2 die Form III. Die Hydrolyse wird als Ionenaustausch K+H+ gedeutet. Das System Rb2OZrO2 enthält ebenfalls nur eine einzige Verbindung, das Rb2Zr2O5, das wahrscheinlich mit K2ZrO2O5 I isotyp ist. An Zirkonat des Lithiums werden nachgewiesen Li4ZrO4, Li2ZrO3, und Li2Zr2O5. Das Dizirkonat entsteht beim Erhitzen von Methanolyseprodukten des Li4ZrO4. Dieses reagiert mit absolutem Methanol gemäß
Katalytische Untersuchungen an Legierungen. XXI. Über die Hydrierung des Acetons an pulverförmigen Nickel‐Legierungskatalysatoren
Authors: Kinza Horst , Rienäcker GÜNther
Published: January 2005

Versuche zur experimentellen Überprüfung der d‐Lücken‐Theorie der Metallkatalysatoren zeigen, daß der Einfluß von Eisenzusätzen zu Nickel‐Katalysatoren durch geringe Kupfersätze aufgehoben werden kann. Kupferzusätze von 5% bewirken eine Änderung der katalytischen Aktivität um etwa eine Größenordnung.
Stress‐coping‐support in rural communities: A model for primary prevention
Authors: Kenkel Mary Beth
Published: January 2005

Conclusion

Because of the relatively small and homogeneous population in rural communities, community‐wide prevention efforts are often more manageable than in urban areas. Community needs and resources can be identified more easily, and the feasibility of different interventions can be assessed more readily.

To guide the rural prevention agent in developing community programs, the stress‐coping‐support framework has been proposed here. The value of this model is that it delineates the aspects of community life that must be assessed, and it outlines several different intervention goals. The model in its most general form proposes that prevention activities should reduce stress, increase coping, and build support. While this model can be applied to any community or target group, the framework has been elaborated here to address the unique physical, occupational, and societal characteristics of rural communities.

Although some of the issues in applying this model to rural, as opposed to urban, areas have been pointed out here, the variation among rural communities has not been addressed fully. The different types of rural communities, e.g., the mining town, the isolated farmlands, the Indian reservation, have unique characteristics which may determine whether a proposed prevention program is needed, feasible, and effective.

It is hoped that rural practitioners, long sensitive to the need for prevention, will use this model to devise additional prevention directions and to generate useful and culturally syntonic programs for their communities.
Southern Appalachia: Analytical models, social services, and native support systems
Authors: Keefe Susan Emley
Published: January 2005

Conclusions

The model of ethnicity has been applied in this paper to Appalachian natives. The problems suffered by Appalachians in terms of high dropout rates, institutional discrimination, prejudice, and stereotyping are familiar to other ethnic minority groups. Yet because the majority of the population in Appalachia are racially indistinct from mainstream Americans, there is resistance to the notion of ethnic difference. This has significant repercussions. Ironically, service providers and others in the region often recognize the distinctive nature of native Appalachians while, at the same time, reaffirming that they are white Americans like anywhere else. This is often said with good intentions. The result, however, justifies a lack of action taken to improve services for native Appalachians. If they are perceived as no different, inequalities go unrecognized and unredressed. If, on the other hand, differences are perceived only on the basis of socioeconomic class and/or rural residence, social services may miss the cultural dimension that may be all‐important in identifying problems and potential means of improvement. It is hoped that application of the notion of ethnicity to mountain people will be helpful in the structuring of human services in the region.
Acquired atrophy of the long process of the incus
Authors: Imauchi Yutaka , Karino Shoutaro , Yamasoba Tatsuya
Published: January 2005

Various lesions can cause conductive hearing loss in a patient with a normal tympanic membrane. These include congenital ossicular anomaly, otosclerosis, and congenital or acquired ossicular fixation and discontinuity. We had an experience with a patient who presented with a conductive hearing loss in both ears, in which small pieces of the long process of the incus were absent and had been replaced with fibrous tissues in both ears. No other abnormalities, such as postinflammatory changes or fixation of the ossicles, were found. Because the long process of the incus undergoes remodeling through resorption and rebuilding throughout life, failure of the remodeling or impaired vascular supply to the long process of the incus may have been the cause of the conductive hearing loss in this patient.
Surgical management of primary and secondary tumors in the pterygopalatine fossa
Authors: Jian Xin‐Chun , Wang Cheng‐Xing , Jiang Can‐Hua
Published: January 2005

OBJECTIVE

This article describes a surgical approach that has been applied to managing primary tumors in the pterygopalatine fossa and secondary tumors involving the pterygopalatine fossa.

PATIENTS AND METHODS

The Barbosa approach was modified by adding a lateral incision in the mandibular gingivobuccal fold from the canine tooth to the retromolar area. This technique was applied to nine patients with primary and secondary tumors in the pterygopalatine fossa. All patients had been observed by clinical examinations, MRI, and CT examinations.

RESULTS

This technique allowed a large, inferiorly based flap to be raised, which includes the parotid gland. The masseter and temporalis muscles were divided horizontally, and the ascending ramus of the mandible was osteotomied between the mandibular angle and the sigmoid notch and reflected to expose the tumor in the pterygopalatine fossa and maxillary sinus. We have applied this technique in 9 patients. Of the 9 patients in our study, 5 (55%) were male and 4 (45%) were female. The median age of the patients at the time of operation for primary and secondary tumors in the pterygopalatine fossa was 49.5 years (range, 19–66 years). Four of the 9 patients had primary tumors in the pterygopalatine fossa. One patient had a tumor in the pterygoaplatine fossa extending into the maxillary sinus, 2 patients had tumors occurring in the maxilla involving the pterygopalatine fossa, 2 patients had tumors from the deep lobe of the parotid gland to the pterygopalatine fossa, and 1 patient had extracranial meningioma. Nine patients have been followed up from 3 months to 9 years and 6 months, and 1 patient had recurrence 2 years and 2 months postoperatively.

CONCLUSION

This technique is especially useful to tumors in the pterygopalatine fossa and tumors in the pterygopalatine fossa extending into the maxillary sinus.
Efficacy of topotecan treatment on antioxidant enzymes and TBA‐RS levels in submandibular glands of rabbits: An experimental study
Authors: Muluk Nuray Bayar , Kisa Üçler , Kaçmaz Murat , Apan Alpaslan , Koç CAN
Published: January 2005

OBJECTIVE

The aim of this study was to investigate the effects of topotecan (Hycamtin), a topoisomerase I inhibiting anticancer agent, on antioxidant enzymes (SOD, CAT, and GSH‐Px) and TBA‐RS values of the submandibular glands of the rabbits.

STUDY DESIGN AND SETTING

The study was conveyed in two groups (Group I, II) and control with a total of 24 rabbits. Eight rabbits in group I received intravenous (i.v.) topotecan (0.25 mg/kg once daily) for 3 days. Eight rabbits in group II received i.v. topotecan (0.5 mg/kg once daily) for 3 days. On the 15th day after administration of topotecan, sub‐mandibular glands were removed and levels of the SOD, CAT, and GSH‐Px and the TBA‐RS in the sub‐mandibular glands of the rabbits were examined.

RESULTS

SOD, CAT, and GSH‐Px values were significantly higher in high‐dose topotecan group compared to control group (P < 0.05). SOD and TBA‐RS values were significantly higher in high‐dose topotecan group compared to low‐dose topotecan group (P < 0.05).

CONCLUSION

It was concluded that, to prevent the hazardous effects of oxygen free radicals due to topotecan, antioxidant enzymes SOD, CAT, and GSH‐Px were increased. The higher levels of the TBA‐RS values in group II showed that permanent damage was present because of high‐dose topotecan administration in the submandibular glands of the rabbits.
New Interpretations of the Spanish Civil War
Authors: NÚÑEZ XOSÉ-MANOEL
Published: January 2005

Michel Lefebvre and Rémi Skoutelsky, Les Brigades Internationales. Images retrouvées (Paris: Editions du Seuil, 2003), 192 pp., €45.00 (hb), ISBN 2-02-052390-6.

Helen Graham, The Spanish Republic at War, 1936–1939 (Cambridge: Cambridge University Press, 2003), 472 pp., £13.99 (pb), ISBN 0-521-45932-X.

Javier Rodrigo, Los campos de concentración franquistas. Entre la historia y la memoria (Madrid: Siete Mares, 2003), 251 pp., €18.00 (pb), ISBN 84-933012-05.

Michael Seidman, A ras de suelo. Historia social de la República durante la Guerra Civil (Madrid: Alianza, 2003), 388 pp., €18.70 (pb), ISBN 84-206-3706-8 (English edition: Republic of Egos. A Social History of the Spanish Civil War (Madison, WI: University of Wisconsin Press, 2002), 304 pp., $24.95 (pb), ISBN 0299178641).

The Spanish Civil War is among the most passionate conflicts of the long twentieth century, as one which arouses considerable emotion, in favour of either the Republican or the Francoist side. Its duration – far beyond what had been predicted in July 1936 by the military rebels and most international observers – together with its rapid conversion into an arena of international dispute between two opposing world-views, ‘fascism’ and ‘anti-fascism’, made it of long-standing interest for world public opinion. Moreover, its internationalisation made it appear as the prelude to the Second World War. The survival of the Francoist dictatorship until 1975 contributed to the fact that the first historical analyses of the Spanish Civil War had to be written abroad and by foreign scholars, mostly French and Anglophone. Even now the Spanish conflict continues to be a matter of interest for non-Spanish scholars, who rely on a long-standing tradition of scholarship on the topic.
Photosynthesis, transpiration, and primary productivity: Scaling up from leaves to canopies and regions using process models and remotely sensed data
Authors: Chen D.‐X. , Coughenour M. B.
Published: January 2005

Biophysical and physiological processes in plants and ecosystems occur over a wide range of spatial and temporal scales. Our knowledge (or models) of these processes is largely at small scales. It is, however, difficult to directly apply mechanistic process‐oriented models over large scales due to heterogeneities in the distributions of processes, and nonlinearities in the functional responses of processes to environmental variables. On the other hand, simple parametric/empirical models in which system complexity is lumped into a small number of parameters have been widely employed to describe processes at larger scales. The variation of these parameters in these simple parametric/empirical models depends on the underlying biophysical processes. In this work, we showed that detailed process models and simple parametric models for primary production and transpiration could be effectively combined to scale leaf photosynthesis and transpiration up to large spatial scales. The integrated process model, General Energy Mass Transfer Model (GEMTM), was used to identify major factors contributing to the variability of the parameters in the parametric models for regional transpiration and primary production and quantify their responses to these factors. Simulations with the GEMTM showed that net carbon assimilation was proportional to intercepted photosynthetically active radiation (IPAR), but the radiation use efficiency (RUE) changed with leaf N concentration, temperature, and atmospheric CO2 concentration; transpiration was linearly correlated with the product of net primary production (NPP) and atmospheric water vapor pressure deficit (VPD), and the slope varied with leaf N concentration. RUE increased with leaf N content asymptotically, and responded to temperature in an asymmetric bell shape pattern with a 22°C and 26°C optimal temperature under current ambient and doubled CO2 concentration, respectively. A simple parametric NPP model and a regional transpiration model (Tr model) were developed from the relationships and parameter values obtained using the GEMTM. The NPP model reasonably simulated the seasonal and interannual variations of accumulated NPP estimated from field data. Simulated regional distribution of NPP over the Central Grassland Region of the United States was consistent with estimates obtained using other models. NPP increased from 120 gC/m2/year in the northwest to 956 gC/m2/year in the southeast. Simulated regional transpiration had a similar spatial distribution pattern as NPP, ranging from about 16 cmH2O/year to 136 cmH2O/year. The transpiration model introduced in this study provides a mechanism to explicitly couple transpiration and NPP in large‐scale analyses, although more complete analysis and validation are required.
Numerical investigation of layered convection in a three‐dimensional shell with application to planetary mantles
Authors: Oldham David , Davies J. Huw
Published: January 2005

Stratified stable layered mantle convection in a three‐dimensional (3‐D) spherical shell is investigated for a range of depth of layer, intrinsic density contrast between the layers (Δρ), and heating mode. Three heating modes are studied: internal heating, bottom heating across core‐mantle boundary, and both combined. For each heating mode, layers were investigated centered at depths from 500 km to 2500 km in 500 km steps and with Δρ from 1 to 5% in 1% steps. We did not find stable layering for Δρ of 1%. Cases with no bottom heating were stable with Δρ of 2%, but Δρ of at least 3% were required by cases with a component of bottom heating. All cases with Δρ of 4% or more were stable. We found that the stability of the layer is strongly dependent on the buoyancy ratio B (B = Δρ ÷ ραΔT, where Δρ is the chemical density increase across the boundary, ρ is the density in the upper layer, α is the thermal expansivity and ΔT is the radial temperature difference across the whole system) with a dense layer becoming unstable B ≈ 0.5. We characterize the height and length scale of the undulations and the area of the interface. Deformations of the interface are largest for cases in which interface is in the midmantle and for cases with small density contrasts. We find that the heating mode does not affect the thermal structure of the layered system, which can be explained with energy balance considerations. The amplitude of the interfacial deformation is found to be unaffected by the heating mode and can be predicted using B. Our results suggest the interfacial thermal boundary layers require large temperature contrasts; therefore the lack of evidence for thermal boundary layers in global seismology studies between 500 and 2500 km depth suggests interfaces at these depths are unlikely.
Effects of the fringe field of Rayleigh‐Taylor instability in the equatorial E and valley regions
Authors: Alam Kherani E. , de Paula Eurico R. , Bertoni Fernando C. P.
Published: January 2005

We present a unified algorithm for the collisional interchange instabilities (Rayleigh‐Taylor and gradient drift instabilities) occurring in the F and E regions of the equatorial ionosphere. The similar underlying mechanism of both instabilities enables us to derive the general two‐dimensional continuity and potential equations. The equations are integrated numerically to study the nonlinear evolution of the polarization field (fringe field) associated with the generalized Rayleigh‐Taylor instability. In particular, the effects of the fringe field into the equatorial E and transition (or valley) regions are investigated. The characteristics of the fringe field beneath the F region are investigated quantitatively for the first time. It is shown that the fringe field is capable of transporting plasma from the region where ions are highly magnetized (i.e., from the valley region). It is further shown that only under strongly driven but realistic conditions, the fringe field recognizes the part of the E region plasma where ions are marginally magnetized. The E region irregularities which are often located in such a region (near 120 km) during evening and nighttime can be effectively convected by the fringe field across the valley region and to the higher altitudes. On the other hand, because of the small ratio of ion‐gyro‐frequency to collision frequency below 120–115 km altitude the fringe field is unable to convect the E region irregularities lying below this region. These characteristics are important in the context of observed valley region echoes which are yet to be explained quantitatively.
Geomorphology, kinematic history, and earthquake behavior of the active Kuwana wedge thrust anticline, central Japan
Authors: Ishiyama Tatsuya , Mueller Karl , Togo Masami , Okada Atsumasa , Takemura Keiji
Published: January 2005

We combine surface mapping of fault and fold scarps that deform late Quaternary alluvial strata with interpretation of a high‐resolution seismic reflection profile to develop a kinematic model and determine fault slip rates for an active blind wedge thrust system that underlies Kuwana anticline in central Japan. Surface fold scarps on Kuwana anticline are closely correlated with narrow fold limbs and angular hinges on the seismic profile that suggest at least ∼1.3 km of fault slip completely consumed by folding in the upper 4 km of the crust. The close coincidence and kinematic link between folded terraces and the underlying thrust geometry indicate that Kuwana anticline has accommodated slip at an average rate of 2.2 ± 0.5 mm/yr on a 27°, west dipping thrust fault since early‐middle Pleistocene time. In contrast to classical fault bend folds the fault slip budget in the stacked wedge thrusts also indicates that (1) the fault tip propagated upward at a low rate relative to the accrual of fault slip and (2) fault slip is partly absorbed by numerous bedding plane flexural‐slip faults above the tips of wedge thrusts. An historic earthquake that occurred on the Kuwana blind thrust system possibly in A.D. 1586 is shown to have produced coseismic surface deformation above the doubly vergent wedge tip. Structural analyses of Kuwana anticline coupled with tectonic geomorphology at 103–105 years timescales illustrate the significance of active folds as indicators of slip on underlying blind thrust faults and thus their otherwise inaccessible seismic hazards.
Mechanics of low‐angle extensional shear zones at the brittle‐ductile transition
Authors: Gueydan Frédéric , Leroy Yves M. , Jolivet Laurent
Published: January 2005

Low‐angle midcrustal ductile shear zones and the related microseismic activity recorded below regions of active extension are seen here as two consequences of strain localization. The feldspar‐to‐mica reaction which occurs once feldspar grains are fractured is the destabilizing mechanism selected to explain the strain localization. The model problem considered to substantiate these claims is solved by numerical means and combines the simple shear due to the rigid gliding of the upper crust (at the velocity of Vs) and the stretch resulting from the extension of the whole crust (at the velocity Ve). The rheological model accounts for dislocation creep of quartz, feldspar, and mica, the feldspar‐to‐mica reaction, and its prerequisite, which is the feldspar fracturing detected by the Mohr‐Coulomb criterion. The one‐dimensional (1‐D) solution, which constrains shear bands to be horizontal, shows the depth partitioning in deformation mode between the simple shear of the low‐viscosity deep crust and the stretching of the highly viscous midcrust. Strain localization occurs during rapid increase of the shearing velocity Vs, corresponding to low values of the velocity ratio Ve/Vs. The 2‐D solution (for Ve/Vs = 10−3) reveals the development of a periodic system of extensional shear bands, dipping at 30° toward the shearing direction at a depth of 12 to 14 km. Shear bands are formed after less than half a million years at the base of the reaction zone defined by the region where feldspar‐to‐mica reaction is completed. Shear bands do not propagate to greater depths because the pressure prevents the feldspar from fracturing and thus the reaction to occur. The periodic system of shear bands defines a midcrustal flat weakened zone within which the equivalent shear stress is enhanced by at least a factor of three at the shear band tips. Brittle fracture could thus occur within the midcrustal flat weakened zone, explaining therefore the microseismicity monitored at these depths in regions of active extension.
Hydrology and circulation in the Strait of Hormuz and the Gulf of Oman—Results from the GOGP99 Experiment: 2. Gulf of Oman
Authors: Pous S. P. , Carton X. , Lazure P.
Published: January 2005

Hydrological, ADCP, and drifting buoy data obtained during the GOGP99 Experiment in October and early November 1999 are analyzed to describe the Persian Gulf Water (PGW) core and the regional circulation in the Gulf of Oman. The warm and salty PGW core flows out of the Strait of Hormuz heading southeastward unto (25°20′N, 57°E), approximately. From there, it cascades down the continental slope, veers southwestward, and joins the Omani coast near (24°50′N, 56°50′E) to form a slope current. This PGW current has then thermohaline maxima on isopycnal σ0 = 26.5, near 220 m depth. Its thermohaline characteristics decrease along its progression to Ra's al Hadd (and then offshore into the Arabian Sea) but maintain a sharp contrast with surrounding waters. Outflow variability at the Strait of Hormuz can be related to downstream fluctuations of the thermohaline maxima in the PGW core at gulf scale and over a 2‐ to 3‐week period. Moreover, several mechanisms (baroclinic instability, flow intermittency, cape effects) are examined to explain the widening of this PGW core upstream and downstream of Ra's al Hamra. In the eastern part of the Gulf of Oman, the regional circulation is a cyclonic gyre. The circulation in the western part of the Gulf is more complex, with the outflow of PGW and southeastward currents in the upper 250 m near the Omani coast, and a recirculation of upwelled waters near Ra's Jagin (on the Iranian coast). The large cyclonic gyre occupies at least the upper 300 m of the water column and undergoes little variation over a month. The PGW outflow in the northern Arabian Sea is southward and located 50–100 km from the coast. It borders a shallower northward current located offshore.
Interannual variability in upper ocean heat content, temperature, and thermosteric expansion on global scales
Authors: Willis Josh K. , Roemmich Dean , Cornuelle Bruce
Published: January 2005

Satellite altimetric height was combined with approximately 1,000,000 in situ temperature profiles to produce global estimates of upper ocean heat content, temperature, and thermosteric sea level variability on interannual timescales. Maps of these quantities from mid‐1993 through mid‐2003 were calculated using the technique developed by Willis et al. [2003]. The time series of globally averaged heat content contains a small amount of interannual variability and implies an oceanic warming rate of 0.86 ± 0.12 watts per square meter of ocean (0.29 ± 0.04 pW) from 1993 to 2003 for the upper 750 m of the water column. As a result of the warming, thermosteric sea level rose at a rate of 1.6 ± 0.3 mm/yr over the same time period. Maps of yearly heat content anomaly show patterns of warming commensurate with ENSO variability in the tropics, but also show that a large part of the trend in global, oceanic heat content is caused by regional warming at midlatitudes in the Southern Hemisphere. In addition to quantifying interannual variability on a global scale, this work illustrates the importance of maintaining continuously updated monitoring systems that provide global coverage of the world's oceans. Ongoing projects, such as the Jason/TOPEX series of satellite altimeters and the Argo float program, provide a critical foundation for characterizing variability on regional, basin, and global scales and quantifying the oceans' role as part of the climate system.
Snow accumulation, surface height change, and firn densification at Summit, Greenland: Insights from 2 years of in situ observation
Authors: Dibb Jack E. , Fahnestock Mark
Published: January 2005

Weekly measurements of surface height change were made at an accumulation forest of 100 stakes at Summit, Greenland, over a 2‐year period (17 August 2000 to 8 August 2002). On average, the surface height relative to the stakes increased 64 (±4.8) cm in the first year and 65 (±5.3) cm in the second, identical to the average (65 ± 4.5 cm yr−1) previously reported for the period 1991–1995 in a similar forest 28 km to the southwest. The continuous 2‐year data set indicates that the rate of surface rise was not constant, with the summers of 2001 and 2002 both showing markedly slower increases. On‐site weather observations suggest that more new snow fell during the summer months than in any other season, consistent with results from previous snow pit and modeling studies yet apparently at odds with the slow rate of height increase. Density profiles from a series of 1‐m‐deep snow pits sampled monthly reveal that the thickness of the most recent year of accumulated snow (25 cm water equivalent) decreased rapidly between late May and early July, and the layers remained thin through early September. The thinning of the top year is clearly due to compaction in the snowpack. Combining the observed variations in annual layer thickness with a linear height increase based on assumed constant accumulation at 0.18 cm d−1 explains much of the variation in surface height found in the stake measurements. Estimated surface height changes can be forced to exactly match the stake measurements by combining changes in annual layer thickness with a variable accumulation rate over the intervals between pits. This exercise suggests that during the 2 years of this study a consistent seasonal pattern in accumulation was not apparent, rather the intervals indicated to have had enhanced accumulation in the first year (August–October and March–April) apparently had reduced accumulation in the second year.
Kinematics of a twisted core complex: Oblique axis rotation in an extended terrane (Betic Cordillera, southern Spain)
Authors: Platzman E. , Platt J. P.
Published: January 2005

The Sierra de las Estancias is a metamorphic core complex that developed during the late Oligocene to early Miocene extensional collapse of the Betic Cordillera. Structural and paleomagnetic analysis shows that the northern half of the complex has been strongly modified by rotation about an inclined axis, requiring reassessment of the kinematics of the extensional phase of deformation. The extensional tectonic event produced two major detachment faults, associated mylonitic foliation and lineation, and pervasive sets of shear bands and brittle normal faults with a top‐to‐NE shear sense. An older foliation was largely transposed and reoriented during this event. The regional foliation now defines a broad antiform with a steep north dipping limb; and the trend of shear‐related lineations swings from NNE to ENE from the southern gently dipping limb into the north dipping limb. The remanent magnetization in a suite of near‐vertical early Miocene mafic dikes intruded into the north dipping limb has a declination of 243° and an inclination of −27°. Assuming that the dikes were originally vertical, a rotation of approximately 50° about an inclined SSW plunging axis preserves the near‐vertical orientation of the dikes and brings the remanence into agreement with the expected orientation for an early Miocene age. Correction for this rotation brings the foliation and lineation in the surrounding schists into orientations subparallel to those on the present southern limb of the antiform, and the dikes into a vertical E‐W orientation. The corrected orientation of the shear‐related lineation (NNE), normal faults, and dikes suggests that the original direction of extension during the late orogenic extensional event in the Internal Betic Cordillera may therefore have been around NNE/SSW, rather than E/W as currently accepted. The observed net tectonic rotation can be decomposed into a series of geologically plausible rotations involving domino‐style rotation due to slip on the late brittle normal faults, tilting about the regional fold axis related to thrust‐ramping onto the Iberian margin during Miocene collision, and a 30° clockwise rotation about a vertical axis related to oblique convergence with the Iberian margin.
Alpine orogenic P‐T‐t‐deformation history of the Catena Costiera area and surrounding regions (Calabrian Arc, southern Italy): The nappe edifice of north Calabria revised with insights on the Tyrrhenian‐Apennine system formation
Authors: Rossetti Federico , Goffé Bruno , Monié Patrick , Faccenna Claudio , Vignaroli Gianluca
Published: January 2005

The nappe‐structured belt of Calabria constitutes the eastward termination of the southern branch of the Alpine Mediterranean belt that delimits the northern edge of the Africa plate. Contrasting hypotheses for the origin and tectonic significance of the north Calabrian nappe edifice have been proposed, and kinematic data from north Calabria have been used to support different interpretations of the Alps‐Apennines linkage and the polarity of the Tethyan subduction in the Apennine region. We reconstruct the architecture of the north Calabria nappe edifice through a multidisciplinary approach which integrates structural investigations with metamorphic thermobarometry and 40Ar/39Ar geochronology. Results from this study indicate that north Calabria consists of a Tertiary nappe stack, resulting from superimposed top‐to‐the‐west extensional shearing (late Oligocene to middle Miocene in age) onto a previously structured top‐to‐the‐east compressional belt (Eocene to Oligocene in age). This study also documents that the top‐to‐the‐west extensional tectonics was achieved by means of regionally sized extensional detachment fault systems, stretching apart and translating as allochthonous fragments the previously accreted units. Thinning operated by top‐to‐the‐west extensional detachment tectonics also resulted in the direct juxtaposition of non‐Alpine or slightly Alpine metamorphosed units (upper plate complex) onto the previously exhumed deep‐seated portions of the orogenic wedge, metamorphosed under blueschist facies metamorphic conditions (lower plate complex). These findings support a new tectonic scenario for the orogenic history of north Calabria, which may be adequately framed within the Tertiary Apennine‐Tyrrhenian system evolution.
Protolith age of the Swakane Gneiss, North Cascades, Washington: Evidence of rapid underthrusting of sediments beneath an arc
Authors: Matzel Jennifer E. P. , Bowring Samuel A. , Miller Robert B.
Published: January 2005

The metamorphic core of the North Cascades largely comprises island arc and oceanic terranes juxtaposed prior to circa 96 Ma magmatism. However, the tectonic affinity of the structurally deepest terrane, the 9–12 kbar Swakane Gneiss, is distinctly different from other terranes in the core; it is not intruded by arc‐related plutons and contains abundant Precambrian zircons. New U‐Pb analyses of detrital zircons from the Swakane Gneiss yield dates from 73 Ma to 1610 Ma with a dominant Late Cretaceous population. These data indicate that the Swakane protolith was deposited as late as 72.5 ± 0.6 Ma, the 206Pb/238U date of the youngest detrital grain. Following deposition, the gneiss was intruded by peraluminous leucogranite sheets that may represent partial melt derived from the gneiss at near‐ to postpeak P‐T conditions. One sheet yielded a U‐Pb crystallization age of 68.36 ± 0.07 Ma, which indicates that the gneiss was deeply buried within 5 Myr of deposition. Two possible mechanisms considered for this rapid burial (∼7 mm/yr) are overthrusting of a forearc or back arc basin by older crystalline rock or underthrusting of trench sediments during low‐angle subduction. The model involving overthrusting of a forearc or back arc basin is most consistent with thermobarometric and isotopic data and the regional geologic setting of the Cascades core. Rapid burial of the Swakane protolith is coincident with burial of sediments that formed the Pelona, Orocopia and Rand schists of southern California; however, differences in peak metamorphic temperatures indicate that conditions of burial must have varied along the plate margin.
Oscillatory‐ and sector‐zoned garnets record cyclic (?) rapid thrusting in central Nepal
Authors: Kohn Matthew J.
Published: January 2005

Garnets with oscillatory zoning (repeated compositional reversals) and sector zoning (crystallographically controlled compositional differences) were discovered in rocks from near the Main Central Thrust in the Langtang region, central Nepal. This zoning results from crystal growth kinetic effects related to extraordinarily rapid, possibly cyclic thrusting. If cyclic thrusting occurred, then timescales of thrust rate inhomogeneities are ∼25 Kyr, implying that satellite determination of modern fault movement rates may not accurately reflect slip rates or strain partitioning in orogens on timescales exceeding thousands of years. Sector zoning in Ca but not Y, Mn, or Mg implies maximum intracrystalline diffusion rates for Ca of ∼10−21 cm2/s at 550°C but faster rates for other elements.