bluuebunny/crossref_metadata_2025 huggingface dataset:
Steel‐framed structures
Authors: Deierlein G G
Published: December 2005

Much of the material reviewed in this article involves recent efforts to develop and apply nonlinear analysis methods for accurate limit states design of steel‐framed structures. Beyond considerations related directly to methods of analysis, this includes reports of tests and other studies to provide behavioral information on members and connections. Emphasized in this review are topics related to overall frame behavior, including analysis methods and criteria for frame and beam‐column stability design, inelastic analysis and behavior of frames with rigid and semi‐rigid connections, and inelastic deformation capacity as influenced by buckling and fracture behavior.
Fatigue design and retrofit of steel bridges
Authors: Bowman Mark D
Published: December 2005

This review examines recent work that has been conducted on the fatigue design, inspection and evaluation of steel bridges. Research studies to evaluate load histories and the influence of cyclic loads on fatigue critical details are discussed for both railway and highway bridge structures. Applications of conventional nondestructive testing and inspection methods are reviewed, and new developments in nondestructive evaluation are discussed. Retrofit and repair procedures that have been used for several different structural details are described. A summary of the fatigue strength and performance of several secondary structural bridge elements is presented. Finally, fatigue assessment procedures which have been proposed recently to design and evaluate new and existing bridge structures are presented.
FRP reinforcement for prestressed concrete structures
Authors: Soudki Khaled A
Published: December 2005

This paper presents the state‐of‐the‐art on the use of fibre‐reinforced polymer (FRP) reinforcement in prestressed concrete. A brief introduction to FRP composite materials is given followed by an overview of recent research work on various aspects of FRP prestressed concrete structural members. Concepts for analysis and design of members prestressed with FRP tendons are discussed. Field demonstrations utilizing FRP prestressing reinforcement, are presented. Finally, conclusions are drawn on the feasibility of using FRP tendons in prestressed concrete applications.
Composite connections
Authors: Leon Roberto T
Published: December 2005

Floor slabs can be utilized effectively to increase the strength and stiffness of a frame by providing continuous slab reinforcement across column lines. This review discusses the influence of floor slabs on the behavior of connections in typical steel buildings, with emphasis on American construction practices. The emphasis is on simplicity of detailing so that the force transfer mechanisms can be understood. The discussion aims to demonstrate three important concepts. First, the detailing of both the slab steel and the steel connection can have a great influence on frame performance, by turning ‘pinned’ connections into partially restrained or semicontinuous ones. Second, ignoring the effect of the slab, as is the conventional practice today, is not always a conservative approach. This is particularly important when seismic or other large accidental overloads occur, as the ductility and toughness of the structure can be impaired by unexpected failure mechanisms tied to slab effects Third, judicious use of composite action in the connections can lead to very economical and structurally efficient solutions. An extensive set of references, both to detailed design guidelines and general background issues, is provided.
Probabilistic structural optimization
Authors: Frangopol Dan M
Published: December 2005

The objective of this review is to present a brief but comprehensive view of probabilistic structural optimization (PSO). An historical perspective is presented, basic concepts and various problem formulations are discussed, and recent developments focusing on practical applications are highlighted. A particular emphasis is placed upon the use of PSO based on consideration of life‐cycle cost in the process of design selection for new structural systems and in the optimal operation of existing ones. Finally, conclusions are drawn and directions for further research are identified.
Timber frame construction for medium‐rise buildings
Authors: Mettem C J , Bainbridge R J , Pitts G C , Enjily V
Published: December 2005

Significant developments which have been taking place recently in relation to medium‐rise timber frame construction in the UK have led to a major research project, Timber Frame 2000. This involves the full‐scale testing of a six‐storey prototype, along with many desk‐based, component‐based and site‐driven ancillary research activities.

This review summarizes interim progress relating to commercial and technical studies, design and specification of the test building. Reference is made to the alternative British and European codes employed in the structural design of the test structure. The technical items due for investigation in the test phases of the building are also outlined.
Developments in insitu and prefabricated masonry for the 21st century
Authors: Caine Johan
Published: December 2005

This article describes Curtins Consulting Engineers' experience in the innovative development of structural prestressed masonry through designs, research and application over the last 35 years. The cross‐fertilization of ideas and developments from other materials, and the unique advantages this has revealed for masonry are described. The techniques are illustrated with examples of applications.

The article also describes some recent developments in prefabrication techniques which give masonry a new horizon for exciting developments and applications without the use of traditional mortar joints. The critical issues relating to the development of insitu masonry into the 21st century are also discussed.
Rehabilitation and reuse of historic masonry buildings in Europe
Authors: Binda L , Anzani A
Published: December 2005

In the last 30 years, the restoration of our cultural heritage has become common practice. Initially, only very important monumental buildings were saved and restored, while the rest were demolished and replaced. Then historic centres and groups of buildings were protected, preserving all structures in a reaction to the previous systematic spoiling of the cultural heritage. Subsequently, it was recognized that all urban structures, including small dwellings, should be respected and preserved with great care.

Nowadays, this respect for old buildings means finding out every detail of their architecture, fabric and structure. The importance of controlling the efficacy of the techniques of repair and improvement is appreciated[1].

This article attempts to provide a state‐of‐the‐art review of the European, and in particular the Italian, attitude towards the reuse of historic buildings with the help of some case histories.
Seismic isolation of civil buildings in the USA
Authors: Kelly J M
Published: December 2005

Designing earthquake‐resistant low‐to medium‐rise structures is problematic in that their fundamental frequency of vibration is in the range of frequencies where earthquake energy is the strongest, so the building acts as an amplifier of the ground vibrations, with the floor accelerations increasing over the height of the building. Ultimately, the seismic design should reduce the accelerations in buildings to below the level of the ground accelerations. To do this the building must be flexible. Incorporating flexibility in a structural frame can cause problems, however: windows may fall out due to wind loads, partition walls may crack and floors may vibrate under foot. For a low‐or medium‐rise building, the necessary flexibility can only be achieved by using base isolation at the foundation level. A number of buildings have been built in the US using this innovative technology; this review will highlight a few of them.
Seismic isolation of civil buildings in Japan
Authors: Fujita Takafumi
Published: December 2005

Japan is the country where seismic isolation is most widely used for civil buildings. Since the Hanshin‐Awaji earthquake of 17 January 1995 when the effectiveness of seismic isolation was demonstrated, base‐isolated buildings have become more popular in Japan. This article reviews seismic isolation systems which have been developed and used in Japan, their effectiveness in the earthquake, present applications, guidelines for safety evaluation of base‐isolated buildings, and future developments for seismic isolation.
Application of active structural control in Japan
Authors: Nishitani A
Published: December 2005

This article reviews the current state of active structural control in building applications. A variety of structural control technologies have been developed which are now being extensively employed in many structures. However, in terms of active structural control, only Japan has implemented active control systems in real full‐size buildings. To date more than 20 buildings in Japan have employed active systems. Details of these active control buildings are summarized in this article.
Space structures and configuration processing
Authors: Nooshin H
Published: December 2005

Many thousands of impressive space structures have been built all over the world for covering sports stadiums, gymnasiums, leisure centres, aircraft hangars, railway stations and many other purposes. A number of these structures have spans of well over 200 m. The objective of this article is to present an overview of space structure forms with an emphasis on lattice grids, barrel vaults and domes. Also included is a brief discussion of the use of conceptual tools for computer‐aided processing of space structure configurations.
Pushover procedure for seismic analysis of buildings
Authors: Tso W K , Moghadam A S
Published: December 2005

This article is a state‐of‐the‐art review of the simplified inelastic analytical procedure commonly referred to as the ‘pushover analysis’ to estimate the seismic response of buildings. The basic steps of a pushover analysis are outlined. The choices available to users in each step are discussed and past studies involving the pushover procedure are briefly reviewed. Finally, the accuracy of the method compared to inelastic dynamic analysis is presented using examples.
Earthquake performance assessment of concrete structures
Authors: Aschheim Mark , Moehle Jack P , Lynn Abraham
Published: December 2005

Performance‐based earthquake engineering provides a framework for comparing seismic demands with member and system capacities in a way that provides a meaningful measure of expected performance. Demands and capacities may be computed using various approaches. Strength‐ and displacement‐based approaches are applied to assess the performance of a reinforced concrete (RC) moment‐resistant frame building damaged in the Northridge earthquake. Because the building was instrumented, the actual response and observed damage can be compared with expectations determined by calculation.
Self‐compacting high performance concrete
Authors: Okamura Hajime , Ouchi Masahiro
Published: December 2005

Self‐compacting concrete was first developed in 1988 in order to achieve durable concrete structures. Since then, various investigations have been carried out and the concrete has been used in practical structures, mainly by large construction companies. Investigations for establishing a rational mix‐design method and self‐compactability testing methods have been carried out from the viewpoint of making it a standard concrete.
Metal silos
Authors: Rotter J Michael
Published: December 2005

Most solids which are handled in large quantities are stored in the form of small particles, for ease of handling. The storage containers for these solids are generically termed silos, though several other words are in use for special applications. Silos are used in most countries in the world to store a huge variety of different particulate or granular solids in bulk. Large silos are of particular importance in agriculture, food processing, power generation, mining, steel, cement, plastics, and chemical process industries. There has been no structural design standard applicable to these large metal structures until the drafting of Eurocode 3 Part 4.1, which is about to be published.

This article reviews the current state of knowledge concerning metal silo structures and presents some of the background and philosophy of the new rules in the draft European standard for steel silos.
Gossamer superconductivity, new paradigm?
Authors: Won Hyekyung , Haas Stephan , Maki Kazumi , Parker David , Dora Balazs , Virosztek Attila
Published: December 2005

We shall review our recent works on d‐wave density wave (dDW) and gossamer superconductivity (i.e. d‐wave superconductivity in the presence of dDW) in high‐T c cuprates and CeCoIn5. a) We show that both the giant Nernst effect and the angle dependent magnetoresistance (ADMR) in the pseudogap phases of the cuprates and CeCoIn5 are manifestations of dDW. b) The phase diagram of high‐T c cuprates is understood in terms of mean field theory, which includes two order parameters Δ 1 and Δ 2, where one order paremeter is from dDW and the other from d‐wave superconductivity. c) In the optimally to the overdoped region we find the spatially periodic dDW, an analogue of the Fulde‐Ferrell‐Larkin‐Ovchinnikov (FFLO) state, becomes more stable. d) In the underdoped region where Δ 2/Δ 1 ≪ 1 the Uemera relation is obtained within the present model. We speculate that the gossamer superconductivity is at the heart of high‐T c cuprate superconductors, the heavy‐fermion superconductor CeCoIn5 and the organic superconductors κ ‐(ET)2Cu(NCS)2 and (TMTSF)2PF6. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic properties and electronic structure of Gd3Cu4X4 (X = Ge, Sn)
Authors: Szytuła A. , Jezierski A. , Penc B. , Wawrzyńska E. , Zygmunt A.
Published: December 2005

Polycrystalline samples of Gd3Cu4X4 (X=Ge, Sn) were investigated by means of magnetometry and XPS. Additionally, calculations of the electronic structures with the TB‐LMTO method were performed for both compounds. They were found to be antiferromagnets; the stannide – below 13 K and the germanide – below 11 K. The electronic structures determined from the photoemission spectra agree well with the results of the calculations. Analysis of the core levels indicates presence of the Cu+1 ions in both compounds. Besides, charge transfers from the Cu and Ge atoms, the latter only in Gd3Cu4Ge4, were detected. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis, Structure, and Thermal Properties of Two New Inorganic‐organic Framework Compounds: Hexaaqua(μ2‐1,2,4,5‐benzenetetracarboxylato)‐bis(N,N′‐1,10‐phenathroline)dicobalt(II) Dihydrate and Hexaaqua(μ2‐1,2,4,5‐benzenetetracarboxylato)‐bis(N,N′‐2,2′‐dipyridylamine)dinickel(II) Tetrahydrate
Authors: Rogan Jelena , Poleti Dejan , Karanović Ljiljana
Published: December 2005

Two binuclear complexes [Co2(C10H2O8)(C12H8N2)2 (H2O)6]·2H2O (1) and [Ni2(C10H2O8)(C10H9N3)2(H2O)6]·4H2O (2) were synthesized and their structures were determined by X‐ray structure analysis. In both structures metal centres are in deformed octahedral environments and they are linked by bis‐monodentately coordinated 1,2,4,5‐benzenetetracarboxylate ligands as bridging units. In the packing arrangements of both compounds, binuclear units are connected by hydrogen bonds forming 2D pseudo‐layers, strengthened by face‐to‐face π‐π stacking interactions. The pseudo‐layers further construct 3D inorganic‐organic frameworks via system of hydrogen bonds. The complexes were also characterized by IR spectroscopy, TG and DSC analysis. Dehydration processes and thermal stability of the complexes are discussed. The dehydration enthalpies are calculated and the possible decomposition mechanisms are assumed.
Syntheses, Crystal Structures, and Antibacterial Activities of Four Schiff Base Copper(II), Zinc(II), and Cadmium(II) Complexes Derived from 2‐[(2‐Dimethylaminoethylimino)methyl]phenol
Authors: You Zhong‐Lu , Zhu Hai‐Liang
Published: December 2005

Four Schiff base complexes, [Zn2L2(NCS)2] (1), [Cd2L2(NCS)2]n (2), [Zn4L2(N3)2Cl4(OH2)(CH3OH)] (3), and [Cu4L2(N3)2Cl4(OH2)(CH3OH)] (4) (where L = 2‐[(2‐dimethylaminoethylimino)methyl]phenol), were synthesized and characterized by elemental analyses, infrared spectroscopy, and single crystal X‐ray determinations. Both 1 and 2 are structurally similar polynuclear complexes. In 1, each Zn atom has a slightly distorted square‐pyramidal coordination configuration. In the basal plane, the Zn atom is coordinated by one O and two N atoms of one L, and by one O atom of another L. The apical position is occupied by one terminal N atom of a coordinated thiocyanate anion. The Zn···Zn separation is 3.179(3) Å. While in 2, the Cd1 atom is six‐coordinated in an octahedral coordination. In the equatorial plane, the Cd1 atom is coordinated by one O and two N atoms of one L, and by one O atom of another L. The axial positions are occupied by the terminal N and S atoms from two bridging thiocyanate anions. The coordination of Cd2 atom in 2 is similar to those of the zinc atoms in 1. The Cd···Cd separation is 3.425(2) Å. Both 3 and 4 are novel tetra‐nuclear complexes. Each metal atom in the complexes has a slightly distorted square‐pyramidal coordination. The arrangements of the terminal metal atoms are similar, involving one O and two N atoms of one L ligand and one bridging Cl atom defining the basal plane, and one O atom of a coordinated water molecule or MeOH molecule occupying the apical position. The coordinations of the central metal atoms are also similar. The basal plane of each metal atom involves one O atom of one L ligand, one terminal Cl atom, and two terminal N atoms from two bridging azide groups. The apical position is occupied by a bridging Cl atom which also acts as a basal donor atom of the terminal metal atom. The Schiff base ligand and the four complexes showed high selectivity and antibacterial activities against most of the bacteria.
Two New Polyoxovanadate‐supported Transition Metal Complexes: [Zn(en)2][Zn(en)2(H2O)2][{Zn(en)(enMe)}As6V15O42(H2O)]·4H2O and [Zn2(enMe)2(en)3][{Zn(enMe)2}As6V15O42(H2O)]·4H2O
Authors: Zheng Shou‐Tian , Chen Yong‐Mei , Zhang Jie , Yang Guo‐Yu
Published: December 2005

Two novel As‐V‐O cluster supported transition metal complexes, [Zn(en)2][Zn(en)2(H2O)2][{Zn(en)(enMe)}As6V15O42(H2O)]·4H2O (1) and [Zn2(enMe)2(en)3][{Zn(enMe)2}As6V15O42(H2O)]·4H2O (2), have been hydrothermally synthesized. The single X‐ray diffraction studies reveal that both compounds consist of discrete noncentral polyoxoanions [{Zn(en)(enMe)}As6V15O42(H2O)]4− or [{Zn(enMe)2}As6V15O42(H2O)]4− cocrystallized with respective zinc coordination complexes. Interestingly, compounds 1 and 2 exhibit the first two polyoxovanadates containing As8V15O42‐(H2O)]6− cluster decorated by only one transition metal complex. Crystal data: 1, monoclinic, P21/n, a = 14.9037(4) Å, b = 18.1243(5) Å, c = 27.6103(7) Å, β = 105.376(6)°, Z = 4; 2 monoclinic, P21/n, a = 14.9786(7) Å, b = 33.0534(16) Å, c = 14.9811(5) Å, Z = 4.
Sm2As4O9: Ein ungewöhnliches Samarium(III)‐Oxoarsenat(III) gemäß Sm4[As2O5]2[As4O8]
Authors: Kang Dong‐Hee , Schleid Thomas
Published: December 2005

Sm2As4O9: An Unusual Samarium(III) Oxoarsenate(III) According to Sm4[As2O5]2[As4O8]

Pale yellow single crystals of the new samarium(III) oxoarsenate(III) with the composition Sm4As8O18 were obtained by a typical solid‐state reaction between Sm2O3 and As2O3 using CsCl and SmCl3 as fluxing agents. The compound crystallizes in the triclinic crystal system with the space group ${\rm P}{\bar 3}$ (No. 2, Z = 2; a = 681.12(5), b = 757.59(6), c = 953.97(8) pm, α = 96.623(7), β = 103.751(7), γ = 104.400(7)°). The crystal structure of samarium(III) oxoarsenate(III) with the formula type Sm4[As2O5]2[As4O8] (≡ 2 × Sm2As4O9) contains two crystallographically different Sm3+ cations, where (Sm1)3+ is coordinated by eight, but (Sm2)3+ by nine oxygen atoms. Two different discrete oxoarsenate(III) anions are present in the crystal structure, namely [As2O5]4− and [As4O8]4−. The [As2O5]4− anion is built up of two Ψ1‐tetrahedra [AsO3]3− with a common corner, whereas the [As4O8]4− anion consists of four Ψ1‐tetrahedra with ring‐shaped vertex‐connected [AsO3]3− pyramids. Thus at all four crystallographically different As3+ cations stereochemically active non‐binding electron pairs (“lone pairs”) are observed. These “lone pairs” direct towards the center of empty channels running parallel to [010] in the overall structure, where these “empty channels” being formed by the linkage of $^{2}_{\infty}\rm \{[SmO_{4}]^{9-}\}$ layers with the ecliptically conformed [As2O5]4− anions and the stair‐like shaped [As4O8]4− rings via common oxygen atoms (O1 – O6, O8 and O9). The oxygen‐atom type O7, however, belongs only to the cyclo‐[As4O8]4− unit as one of the two different corner‐sharing oxygen atoms.
The Monohydrate of Basic Mercuric Nitrate, [Hg(OH)](NO3)(H2O)
Authors: Nolte Matthias , Pantenburg Ingo , Meyer Gerd
Published: December 2005

Colourless single crystals of [Hg(OH)](NO3)(H2O) were obtained by slow evaporation of an aqueous solution of Hg(NO3)2 and Bi(NO3)3. The crystal structure (orthorhombic, Pbca, Z = 8, a = 943.2(2), b = 697.6(1), c = 1349.0(2) pm, R1(all) = 0.0780) contains [Hg(OH)] = …OH–Hg–OH–Hg… zig zag chains (O–Hg–O angle: 168°, Hg–O–Hg angle: 112°, Hg–OH distance: 212 pm) to which one water molecule is attached loosely. The [Hg(OH)](H2O) chains are connected via bis‐monodentate‐bridging nitrate ions to corrugated layers that are stacked in the [001] direction. Hg2+ has an effective 2+2+2(+1) coordination.
EARLY BLACK DOCTORS IN SOUTH AFRICA
Authors: DIGBY ANNE
Published: December 2005

The article adopts the approach of a group biography in discussing the careers and ambitions of early black South African doctors selecting both those trained abroad, and the first cohorts trained within South Africa who graduated at the Universities of Cape Town and the Witwatersrand from 1945–6. It focuses on the ambiguities involved, by looking at tensions between professional altruism and entrepreneurialism in pursuing a medical career, as well as that between self-interest and selflessness in attempting to balance the requirements of a medical practice against those involved in political leadership. The paper highlights the significance of the political leadership given by black doctors in the mid-twentieth century and indicates the price paid for this in loss of medical resources under the apartheid regime. Two annexes provide original data on the medical and political contributions of individuals.
Crop losses to pests
Authors: OERKE E.-C.
Published: December 2005

Productivity of crops grown for human consumption is at risk due to the incidence of pests, especially weeds, pathogens and animal pests. Crop losses due to these harmful organisms can be substantial and may be prevented, or reduced, by crop protection measures. An overview is given on different types of crop losses as well as on various methods of pest control developed during the last century.

Estimates on potential and actual losses despite the current crop protection practices are given for wheat, rice, maize, potatoes, soybeans, and cotton for the period 2001–03 on a regional basis (19 regions) as well as for the global total. Among crops, the total global potential loss due to pests varied from about 50% in wheat to more than 80% in cotton production. The responses are estimated as losses of 26–29% for soybean, wheat and cotton, and 31, 37 and 40% for maize, rice and potatoes, respectively. Overall, weeds produced the highest potential loss (34%), with animal pests and pathogens being less important (losses of 18 and 16%). The efficacy of crop protection was higher in cash crops than in food crops. Weed control can be managed mechanically or chemically, therefore worldwide efficacy was considerably higher than for the control of animal pests or diseases, which rely heavily on synthetic chemicals. Regional differences in efficacy are outlined. Despite a clear increase in pesticide use, crop losses have not significantly decreased during the last 40 years. However, pesticide use has enabled farmers to modify production systems and to increase crop productivity without sustaining the higher losses likely to occur from an increased susceptibility to the damaging effect of pests.

The concept of integrated pest/crop management includes a threshold concept for the application of pest control measures and reduction in the amount/frequency of pesticides applied to an economically and ecologically acceptable level. Often minor crop losses are economically acceptable; however, an increase in crop productivity without adequate crop protection does not make sense, because an increase in attainable yields is often associated with an increased vulnerability to damage inflicted by pests.
Multivalence and Collaboration in Benjamin Britten’s Death in Venice
Authors: SARA LONGOBARDI RUTH
Published: December 2005

A multivalent conception of opera, one that understands each operatic domain as functioning independently of every other domain, is one way of accounting for marks of contention: passages in which the music seems not to fit the events, characters, or atmospheres of its accompanying text. With that analytical framework, opera, frequently conceived of as two media subsumed under a cohesive initiative, emerges as a site of elaborate, sometimes contentious, interactions.

Scene 11 of Death in Venice exhibits considerable signs of multivalence. The unusual musical construct of this scene suggests points of reference that are absent in the libretto, and, accordingly, the two media do not distil the protagonist’s character in this passage but rather broaden the representational space into a heteroglossic network of associations.

The incongruities in this scene thereby disrupt the sense of ideological affinity between media, and signal significant differences among artistic perspectives and values. In particular, musico-dramatic dissonances highlight varying concerns regarding the opera’s topic of homosexuality. If the protagonist’s homosexual trajectory in Death in Venice’s libretto ends in shame and death, this is a trajectory that the music might be heard as opposing, even if we cannot translate its meanings precisely.
Processes of equatorial thermal structure at Jupiter: An analysis of the Galileo temperature profile with a three‐dimensional model
Authors: Majeed T. , Waite J. H. , Bougher S. W. , Gladstone G. R.
Published: December 2005

The Jupiter Thermospheric General Circulation Model (JTGCM) calculates the global dynamical structure of Jupiter's thermosphere self‐consistently with its global thermal structure and composition. The main heat source that drives the thermospheric flow is high‐latitude Joule heating. A secondary source of heating is the auroral process of particle precipitation. Global simulations of Jovian thermospheric dynamics indicate strong neutral outflows from the auroral ovals with velocities up to ∼1.2 km/s and subsequent convergence and downwelling at the Jovian equator. Such circulation is shown to be an important process for transporting significant amounts of auroral energy to equatorial latitudes and for regulating the global heat budget in a manner consistent with the high thermospheric temperatures observed by the Galileo probe. Adiabatic compression of the neutral atmosphere resulting from downward motion is an important source of equatorial heating from the top boundary of the JTGCM to 0.06 μbar. The adiabatic heating continues to dominate between 0.06 and 0.2 μbar, but with the addition of comparable heating due to horizontal advection induced by the meridional flow. Thermal conduction plays an important role in transporting heat down to lower altitudes (>0.2 μbar). The total heating transported in this region is radiated away by infrared hydrocarbon cooling via CH4 (7.8 μm) and C2H2 (12.6 μm) emissions.
Morphology and flow fields of three‐dimensional dunes, Rio Paraná, Argentina: Results from simultaneous multibeam echo sounding and acoustic Doppler current profiling
Authors: Parsons D. R. , Best J. L. , Orfeo O. , Hardy R. J. , Kostaschuk R. , Lane S. N.
Published: December 2005

Most past studies of river dune dynamics have concentrated on two‐dimensional (2‐D) bed forms, with constant heights and straight crest lines transverse to the flow, and their associated turbulent flow structure. This morphological simplification imposes inherent limitations on the interpretation and understanding of dune form and flow dynamics in natural channels, where dune form is predominantly three‐dimensional. For example, studies over 2‐D forms neglect the significant influence that lateral flows and secondary circulation may have on the flow structure and thus dune morphology. This paper details a field study of a swath of 3‐D dunes in the Rio Paraná, Argentina. A large (0.35 km wide, 1.2 km long) area of dunes was surveyed using a multibeam echo sounder (MBES) that provided high‐resolution 3‐D detail of the river bed. Simultaneous with the MBES survey, 3‐D flow information was obtained with an acoustic Doppler current profiler (ADCP), revealing a complicated pattern of dune morphology and associated flow structure within the swath. Dune three‐dimensionality appears intimately connected to the morphology of the upstream dune, with changes in crest line curvature and crest line bifurcations/junctions significantly influencing the downstream dune form. Dunes with lobe or saddle‐shaped crest lines were found to have larger, more structured regions of vertical velocity with smaller separation zones than more 2‐D straight‐crested dunes. These results represent the first integrated study of 3‐D dune form and mean flow structure from the field and show several similarities to recent laboratory models of flow over 3‐D dunes.
El Niño and La Niña influence on droughts at different timescales in the Iberian Peninsula
Authors: Vicente‐Serrano Sergio M.
Published: December 2005

This paper seeks to determine the impact of extreme phases of the Southern Oscillation (SO, El Niño/La Niña) on droughts in the Iberian Peninsula. For this purpose, 51 precipitation series (1910–2000) were used. A spatial classification based on monthly precipitation records was made to identify homogeneous regions and to analyze any spatial differences in the influence of these extreme phases. For each region a drought index was calculated (standardized precipitation index) at timescales of 1, 3, 6 and 12 months. El Niño and La Niña years were identified using the Southern Oscillation index (SOI), in line with studies conducted elsewhere. Mean values of the drought index were calculated each month for the four timescales during El Niño and La Niña years as well as for the year following these events. The statistical significance of any anomalies was evaluated by means of the nonparametric Wilcoxon Mann‐Whitney test. The results indicate that extreme phases of the SO significantly affect the occurrence of droughts in the Iberian Peninsula. Moreover, spatial and temporal differences, depending on the timescale used, were identified. Large areas of the Iberian Peninsula are affected by significant negative values of SPI during the final months of La Niña years and the initial months of the following year. In contrast, other areas are affected by dry conditions during the first months of El Niño years as well as during the summers and autumns of the following year. The spatial differences in drought conditions during extreme phases of the SO are noticeable, and the drought signal is more consistent for La Niña than it is for El Niño years. Finally, the usefulness of these results for drought prediction and early warning systems is discussed.
Assessing the predictability of extreme rainfall seasons over southern Africa
Authors: Landman Willem A. , Botes Stephanie , Goddard Lisa , Shongwe Mxolisi
Published: December 2005

A model output statistics (MOS) technique is developed to investigate the potential rainfall forecast skill for extreme seasons over southern Africa. Rainfall patterns produced by the ECHAM4.5 atmospheric GCM are statistically recalibrated to regional rainfall for the seasons of September–November, December–February, March–May and June–August. Archived records of the GCM simulated fields are related to observed rainfall through a set of canonical correlation analysis (CCA) equations. Probabilistic forecast skill (RPSS and ROC) of MOS‐recalibrated simulations for 5 equi‐probable categories is assessed using a 3‐year‐out cross‐validation approach. High skill RPSS values are found for the DJF and MAM seasons. Although ROC scores for DJF and MAM are larger than 0.5 for all categories (scores less than 0.5 suggest negative skill), scores for DJF show that the extreme categories are more predictable than the inner categories and scores for MAM show that skill is mostly associated with the extremely wet category. The GCM's ability to reproduce tropical‐temperate trough variability constitutes the main source of predictability for DJF and MAM.
How accurate did GCMs compute the insolation at TOA for AMIP‐2?
Authors: Raschke Ehrhard , Giorgetta Marco A. , Kinne Stefan , Wild Martin
Published: December 2005

Monthly averages of solar radiation reaching the Top of the Atmosphere (TOA) as simulated by 20 General Circulation Models (GCMs) during the period 1985–1988 are compared. They were part of submissions to AMIP‐2 (Atmospheric Model Intercomparison Project). Monthly averages of ISCCP‐FD (International Satellite Cloud Climatology Project – Flux Data) are considered as reference. Considerable discrepancies are found: Most models reproduce the prescribed Total Solar Irradiance (TSI) value within ±0.7 Wm−2. Monthly zonal averages disagree between ±2 to ±7 Wm−2, depending on latitude and season. The largest model diversity occurs near polar regions. Some models display a zonally symmetric insolation, while others and ISCCP show longitudinal deviations of the order of ±1 Wm−2. With such differences in meridional gradients impacts in multi‐annual simulations cannot be excluded. Sensitivity studies are recommended.
The response of the Southern Annular Mode, the East Australian Current, and the southern mid‐latitude ocean circulation to global warming
Authors: Cai W. , Shi G. , Cowan T. , Bi D. , Ribbe J.
Published: December 2005

Climate models predict an upward trend of the Southern Annular Mode (SAM) in response to increasing atmospheric CO2 concentration, however the consequential impact of this change on oceanic circulation has not been explored. Here we analyse the outputs of a series of global warming experiments from the CSIRO Mark 3 climate model. We show that although for the zonal wind stress change the maximum is located at approximately 60°S, in terms of the change in surface wind stress curl, the maximum is situated at approximately 48°S. This change in the wind stress curl causes a spin‐up of the entire southern midlatitude ocean circulation including a southward strengthening of the subtropical gyres, particularly the East Australia Current (EAC). The intensified EAC generates a warming rate in the Tasman Sea that is the greatest in the Southern Hemisphere (SH) with significant implications for sea level rise. The pan‐Southern Ocean scale suggests a broad impact on the marine ecosystem of the entire southern midlatitude ocean.
Seasonal variation of high‐molecular‐weight compounds in the water‐soluble fraction of organic urban aerosols
Authors: Samburova V. , Szidat S. , Hueglin C. , Fisseha R. , Baltensperger U. , Zenobi R. , Kalberer M.
Published: December 2005

Aerosol samples were collected in Zurich, Switzerland, at an urban background site and were analyzed with size exclusion chromatography (SEC) and laser/desorption ionization mass spectrometry (LDI‐MS) for water‐soluble organic compounds with high molecular weight. Daily samples were collected during two campaigns in winter and summer, for 1 month each. The concentration of high‐molecular‐weight compounds (humic‐like substances (HULIS)) was between 0.4 and 4 μg/m3 in winter and summer. The most intense signals in the LDI‐MS mass spectra were measured between m/z150 and 500, comparing well with the mode of the two main high mass peaks determined with SEC corresponding to masses between 200 and 600 Da. For the maximum molecular weight, however, different results were obtained by the two techniques: whereas a maximum molecular weight between 1300 and 3300 Da was found with SEC, hardly any peaks above m/z700 were measured with LDI‐MS. During summer the maximum molecular weight of HULIS (determined with SEC) correlates positively with several parameters such as ozone and increased temperature indicative of enhanced atmospheric photo‐oxidation. The HULIS concentration also correlates positively with the oxalic acid concentration in the particles. This suggests that HULIS are generated by secondary processes in summer. The lack of such correlations during winter suggests that other sources and processes might be important during colder seasons.
Assessment of TOMS UV bias due to absorbing aerosols
Authors: Arola Antti , Kazadzis Stelios , Krotkov Nickolay , Bais Alkis , Gröbner Julian , Herman Jay R.
Published: December 2005

We compared NASA Total Ozone Mapping Spectrometer (TOMS) overpass irradiances against ground‐based Brewer measurements at Ispra, Italy, and Thessaloniki, Greece, with the main objective of evaluating the effect of absorbing aerosols on TOMS UV bias using direct measurements of aerosol optical properties. Dependence of the TOMS/Brewer bias on aerosol absorption optical depth is significant. Our study demonstrates that the bias between TOMS and measured Brewer 324 nm irradiances increases with increasing aerosol absorption optical depth τabs. The correlation coefficients between the ratio TOMS/Brewer and τabs at Ispra and Thessaloniki are ∼0.7 or more and ∼0.8 or more, respectively, depending on the range of solar zenith angle values selected for the analysis. We found that the correlation with single‐scattering albedo ω or aerosol optical depth is significantly smaller than with τabs. If measurements or climatology of τabs are available in the UVB range, the TOMS UV product can be postcorrected for absorbing aerosols using similar site‐dependent regressions as established in our study. If no correction is applied, the mean positive biases between TOMS and Brewer 324 nm irradiances in Thessaloniki and Ispra are 19.2% and 29.7%, respectively, while the standard deviations are 8.9% and 16.5%. Depending on the level of correction, the mean positive bias can be essentially removed, and the standard deviations can be reduced down to ∼6% and ∼10%, respectively.
Cryptoendolithic alteration of Antarctic sandstones: Pioneers or opportunists?
Authors: Blackhurst R. L. , Genge M. J. , Kearsley A. T. , Grady M. M.
Published: December 2005

The cryptoendolithic habitat of the Antarctic Dry Valleys has been considered a good analogy for past Martian ecosystems, if life arose on the planet. Yet cryptoendoliths are thought to favor the colonization of rocks that have a preexisting porous structure, e.g., sandstones. This may weaken their significance as exact analogues of potential rock‐colonizing organisms on Mars, given our current understanding of the dominant volcanic nature of Martian geology. However, the production of oxalic acid, by these lichen‐dominated communities, and its weathering potential indicate that it could be an aid in rock colonization, enabling endoliths to inhabit a wider variety of rock types. Utilizing ICP‐AES and scanning electron microscope techniques, this study investigates elemental and mineralogical compositions within colonized and uncolonized layers in individual sandstone samples. This is in order to determine if the weathering of mineral phases within the colonized layers causes an increase in the amount of pore space available for colonization. The results show that colonized layers are more weathered than uncolonized, deeper portions of the rock substrate. Layers within uncolonized samples have uniform compositions. Differences between the colonized and uncolonized layers also occur to varying extents within colonized rocks of different mineralogical maturities. The results confirm that cryptoendoliths modify their habitat through the production of oxalic acid and suggest that over time this directly increases the porosity of their inhabited layer, potentially increasing the biomass it can support.
On the origin of the 100‐kyr cycles in the astronomical forcing
Authors: Berger A. , Mélice J. L. , Loutre M. F.
Published: December 2005

Investigations during the last 25 years have demonstrated that the astronomically related 19‐, 23‐, and 41‐kyr quasiperiodicities actually occur in long records of the Quaternary climate. However, the same investigations also identified the largest climatic cycle as being about 100 kyr long. As the 100‐kyr variations in standing insolation due to eccentricity change are too small, they cannot be the direct cause of the ice ages. This is the reason why most of the modeling studies attempting to explain the relation between the astronomical forcing and climatic change have focused on this 100‐kyr cycle. In this paper, we will show the astronomical origin of the periods at about 100 kyr that characterize the long‐term variations of eccentricity, of its first derivative, of the frequency modulation of obliquity, and of the inclination of the Earth's orbit on the invariable plane of reference. Five independent values are found between 95 and 107 kyr, and a wavelet signature is suggested to test the possible relationships between the astronomical and climatic variables. Proxy records from deep‐sea cores and European Programme for Ice Coring in Antarctica ice core and modeling results from the Louvain‐la‐Neuve two‐dimensional model are used for illustration.
Photodetachment spectroscopy of PtBr42−: Probing the Coulomb barrier of a doubly charged anion
Authors: Löffler D. , Weber J. M. , Kappes M. M.
Published: December 2005

We probe the repulsive Coulomb barrier of the doubly charged anion PtBr42− by photodetachment spectroscopy. The results are discussed in terms of models for the photoemission process, the excitation spectrum of PtBr42−, and calculations of the energy-dependent tunneling probability for various model potentials.
Analytic description of high poloidal beta equilibrium with a natural inboard poloidal field null
Authors: Shi Bingren
Published: December 2005

Analytical high poloidal beta equilibria for toroidally axisymmetric plasmas with arbitrary aspect ratio and elongation are described. These equilibria that can describe a transition from nondivertor to divertor configuration are exact solutions of the Grad-Shafranov equation when the toroidal current density is quasiuniform. Generally, these are high poloidal beta equilibria, limited by the appearance of a natural inboard poloidal field null. Some of their properties, including the nonuniformity of the poloidal magnetic field in the poloidal direction, the safety factor profile and the magnetic shear profile near the separatrix, the parameter dependence of the poloidal beta βp and εβp, as well as the toroidal beta βT on the aspect ratio and the elongation of the magnetic surface, are discussed. Applications to experiments of the Tokamak Fusion Test Reactor (TFTR) [Sabbagh et al., Phys. Fluids B3, 2277 (1991)] are particularly analyzed.
Robust heavy-ion-beam illumination against a direct-drive-pellet displacement in inertial confinement fusion
Authors: Miyazawa K. , Ogoyski A. I. , Kawata S. , Someya T. , Kikuchi T.
Published: December 2005

Nonuniformity of heavy-ion-beam (HIB) illumination is one of key issues in the HIB inertial confinement fusion (ICF): implosion symmetry should be less than a few percent in order to compress a fuel sufficiently and release fusion energy effectively. In this paper a new HIB illumination scheme is presented in order to realize a robust illumination scheme against a displacement of a direct-driven fuel pellet in an ICF reactor. It is known that the HIB illumination nonuniformity is sensitive to a little pellet displacement from a reactor chamber center; a pellet displacement of only 50–100μm was tolerable in the conventional HIB illumination schemes. In this paper by three-dimensional computer simulations a new robust HIB illumination scheme was found, in which a 200–300μm displacement is allowed.
Slow mode waves and mirror instability in gyrotropic Hall magnetohydrodynamic model
Authors: Hau L.-N. , Wang B.-J. , Teh W.-L.
Published: December 2005

Recently the nonlinear magnetohydrodynamic (MHD) model corrected by pressure anisotropy and Hall current arising from the ion inertia is applied to construct slow or mirror mode structures and compare with the observation in the Earth’s magnetosphere [K. Stasiewicz, Phys. Rev. Lett. 93, 125004 (2004)]. A serious issue is also raised of whether the Hall MHD model is appropriate for describing the high beta plasma and is capable of reproducing the wave dispersion found in kinetic theory [O. Pokhotelov et al., Phys. Rev. Lett. 95, 129501 (2005)]. In this paper we give an overview of the characteristics of linear slow mode waves and mirror instability within the context of the gyrotropic Hall MHD model closed with various energy equations. The properties examined include the phase speed, the compressibility of plasma density and magnetic field, the magnetic polarization of slow mode waves, as well as the criteria for mirror instability and their dependences on pressure anisotropy, plasma beta, propagation angle, and energy closures. The analyses help to clarify the applicability and limitation with applying the gyrotropic Hall MHD model to the observed slow or mirror mode structures.
Nonlinearly coupled whistlers and dust-acoustic perturbations in dusty plasmas
Authors: Shukla P. K. , Mond M. , Kourakis I. , Eliasson B.
Published: December 2005

The nonlinear interaction between magnetic-field-aligned coherent whistlers and dust-acoustic perturbations (DAPs) in a magnetized dusty plasma is considered. The interaction is governed by a pair of equations consisting of a nonlinear Schrödinger equation for the modulated whistler wave packet and an equation for the nonresonant DAPs in the presence of the ponderomotive force generated by the whistlers. The coupled equations are employed to investigate the occurrence of modulational instability, in addition to the formation of whistler envelope solitons. This investigation is relevant to amplitude modulated electron whistlers in magnetized space dusty plasmas.
Studies of Disaccharide Solvation—Molecular Dynamics versus HPLC Retention
Authors: Cheetham Norman W. H. , Dasgupta Paramita
Published: December 2005

Molecular dynamics simulations have been used to assess the conformational behaviour of seven disaccharides in aqueous solution. Solvation decreased the overall conformational fluctuations of the sugars, compared to in vacuo simulations using a high dielectric constant. The most significant finding was a linear correlation between the experimental chromatographic retention parameter K´ and a molecular modelling parameter based on the next-nearest oxygen–oxygen distances in the disaccharides. The results support previous proposals for a stereospecific hydration model for carbohydrates and demonstrate the utility of a combined experimental/molecular modelling approach to its study.
The 3-Hydroxycineoles
Authors: Carman Raymond M. , Robinson Ward T. , Wallis Craig J.
Published: December 2005

Data concerning the 3-hydroxycineoles 1 and 2 are provided to enable the ready identification of these metabolites and to determine their enantiomeric excess in mixtures. An unusual SN2-type inversion at a tertiary center is observed during one synthetic approach.