bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Crystal Structure of Tellurium(II) bis(2‐methoxycarbonylethanethiolate): A Novel Coordination Mode of Tellurium
Authors: Fleischer Holger , Hennig Sandra , Schollmeyer Dieter
Published: October 2003

The tellurium(II) dithiolates Te[SCH2CH2C(O)OCH3]2, (1), Te[SCH2CH2CH2SC(O)CH3]2, (2), and Te[SCH2CH2CH2CH2SC(O)CH3]2, (3) were synthesized from Te(StBu)2 and the corresponding thiol. All compounds are sensitive toward higher temperatures and light and decompose to elemental tellurium and the disulfide. In the solid state, the Te atom of 1 exhibits the novel Te(S2Te2) coordination mode. Additionally to the two Te—S bonds, each Te atom forms two long Te···Te contacts to neighboring molecules, leading to a coordination number of four and a distorted sawhorse configuration. No intramolecular Te···O interactions are present in the solid state, in accordance with ab initio calculations (MP2/ecp‐basis) for the isolated molecule. 125Te NMR shifts of all compounds lay within a narrow range and close to the respective shift of other Te(SCH2R)2 compounds. VT 125Te NMR spectra gave no hint to donor acceptor interactions in solution for any of the compounds and thus corroborate results from IR‐spectroscopy, ab initio geometry optimizations, and thermochemical calculations.
Non‐Isomorphic Chlorine—Bromine Substitution in the Copper(I) Halide π‐Complexes with 1‐Allyl‐4‐aminopyridinium
Authors: Goreshnik E. A. , Schollmeyer D. , Mys'kiv M. G.
Published: October 2003

By alternating‐current electrochemical synthesis crystals of {Cu[H2NC5H4N(C3H5)]Br2}˙H2O (I), {Cu[H2NC5H4N(C3H5)]Br0.65Cl1.35}˙H2O (II) and {Cu[H2NC5H4N(C3H5)]Cl2} (III) π‐complexes have been obtained and structurally investigated. The I and II compounds are isostructural and crystallize in a monoclinic sp. gr. P21/c, I: a = 7.359(2)Å, b = 12.3880(6)Å, c = 13.637(3)Å, β = 107.03(1)°, V = 1188.7(4)Å3, Z = 4 for C8H13N2OBr2Cu composition, R = 0.0293 for 2140 reflections. II: a = 7.2771(6)Å, b = 12.3338(3)Å, c = 13.4366(7)Å, β = 107.632(2)°, V = 1149.3(1)Å3, Z = 4 for C8H13N2Br0.65Cl1.35Cu composition, R = 0.0463 for 2185 reflections. Metal and halogen atoms form centrosymmetric Cu2X4 dimers. Each copper atom is surrounded by three halogen atoms and by a weakly bonded C=C‐group of the onium moiety. Isolated {Cu[H2NC5H4N(C3H5)]}2X4 dimers are combined into a three‐dimensional network due to a bridging function of water molecules via a system of rather strong hydrogen bonds. Chlorine derivative III crystallizes in another structure type: sp. gr. C2/c, a = 21.568(7)Å, b = 7.260(2)Å, c = 13.331(3)Å, β = 95.65(2)°, V = 2077(2)Å3, Z = 8 for C8H11N2Cl2Cu composition. Copper atom, included in CuCl2— isolated fragment, is coordinated to a C=C‐bond of ligand moiety. N‐H…Cl hydrogen bonds unite Cu[H2NC5H4N(C3H5)]Cl2 subunits into infinite ribbons. π‐Interaction in III appears to be more effective than in I and II.
The Crystal Structure of Ba3Cu2Al2F16: a Relative of Ba4Cu2Al3F21
Authors: Gredin Patrick , Corbel Gwenaël , Wright Jonathan P. , Dupont Nathalie , de Kozak Ariel
Published: October 2003

Ba3Cu2Al2F16 is monoclinic: a = 7.334(1)Å, b = 5.320(2)Å, c = 16.022(1)Å, β = 96.34(1)°, Z = 2. Its crystal structure was solved in the space group P21 (No. 4) from synchrotron X‐ray single crystal data using 2685 unique reflections (2639 with Fo/σ(Fo) > 4). The final R factor is 0.044. The structure consists of a succession along the c‐axis of the cell of three layers of two different kinds of sheets developing in the (a, b) plane. The first one, formulated [(AlF5)2]∞4— and hereafter named A, is built up from infinite cis‐chains of aluminium‐fluorine octahedra [AlF6], linked by two vertices and distanced by a. The second one, formulated [Cu2AlF11]∞4— and named B, is bidimensional. It is constituted of distorted copper‐fluorine octahedra [CuF6], linked by edges, which form infinite chains interconnected by three vertices of isolated [AlF6] octahedra. The stacking sequence of the sheets is (A, B, B)∞. The barium ions, 12‐coordinated, are inserted between the sheets. The crystal structure of Ba3Cu2Al2F16 is closely related to that of Ba4Cu2Al3F21. Only the proportion and the stacking sequence of the two kinds of sheets in the c‐direction differ, according to two different compositions and two different symmetries.
Structural and Spectroscopic Characterization of Two New Thallium(I)/Thiosaccharinate Complexes
Authors: Tarulli Susana H. , Quinzani Oscar V. , Piro Oscar E. , Castellano Eduardo E. , Baran Enrique J.
Published: October 2003

The crystal structures of [Tl(tsac)] (1) and [Tl(tsac)(ophen)] (2) (tsac = anion of thiosaccharin; ophen = 1, 10 phenanthroline) have been determined at 116 K by single crystal X‐ray diffractometry. Complex 1 crystallizes in the monoclinic space group P21/a with Z = 4 and complex 2 in the monoclinic space group C2/c with Z = 8.In both complexes TI is coordinated to a thiosaccharinate anion through its sulphur and nitrogen atoms. A distorted eight fold coordination sphere around the cation in complex 1 is completed with two other longer Tl‐S bonds and four Tl···O contacts with five symmetry related neighbouring thiosaccharinate anions. A phenanthroline molecule acting as a bidentate ligand through its nitrogen atoms completes a four‐fold coordination around the metal atom in complex 2. The infrared spectra of both complexes were also recorded and their most important features discussed on the basis of its structural peculiarities.
Single Crystals of NaPrTe2 with LiTiO2‐Type Structure
Authors: Lissner Falk , Schleid Thomas
Published: October 2003

During attempts to synthesize rare‐earth nitride tellurides black and bead‐shaped single crystals of the title compound sodium praseodymium(III) ditelluride (NaPrTe2) were obtained as a by‐product by reacting a mixture of praseodymium, sodium azide (NaN3) and tellurium at 900 °C for seven days in evacuated torch‐sealed silica vessels. NaPrTe2 crystallizes cubic (space group: Fd3¯m, Z = 16; a = 1285.51(9) pm, Vm = 79.96(1) cm3/mol, R1 = 0.028 for 146 unique reflections) and exhibits the Na+ and Pr3+ cations in slightly distorted octahedra of six telluride anions (d(Na—Te) = 325 pm, d(Pr—Te) = 317 pm) each. The main characteristics of this new structure type for alkali‐metal rare‐earth(III) dichalcogenides can be derived from the rock‐salt type structure (NaCl, cubic closest‐packed Te2— arrangement, all octahedral voids occupied with Na+ and Pr3+) with alternating layers consisting of Na+ and Pr3+ cations in a ratio of 3:1 and 1:3, respectively, piled along the [111] direction.
Bulky Amido Ligands in Rare Earth Chemistry — Syntheses, Structures, and Catalysis
Authors: Roesky Peter W.
Published: October 2003

The amido metal chemistry of the rare earth elements is a rapid developing area in coordination chemistry. Especially bulky mono and bidentate amido and amidinates have been introduced as ligands in rare earth chemistry. Due to these sterically demanding ligands, the coordination numbers of the rare earth elements are significantly reduced. This article focuses on two of these bulky ligand systems: bis(trimethylsilyl)amide and aminotroponiminates.

The homoleptic bis(trimethylsilyl)amides of rare earth elements, [Ln{N(SiMe3)2}3], are well established compounds in synthetic chemistry. Therefore, this article reviews recent progress in the catalytic application of these compounds. In the second part of this research report, it is shown that N, N′‐disubstituted aminotroponiminates and mono bridged bisaminotroponiminates can be used as cyclopentadienyl alternatives. Achiral and chiral aminotroponiminates have been used. The structural properties, reactivities as well as the catalytic and synthetic applications of the aminotroponiminates complexes will be outlined in this article.
Strukturen der Alkalimetallsalze aromatischer, heterocyclischer Amide: Synthese und Struktur von Kronenether‐Addukten der Alkalimetall‐indolide
Authors: Heldt Ingo , Borrmann Tobias , Behrens Ulrich
Published: October 2003

Die Synthese von fünf Alkalimetall‐indolid‐Kronenether‐Komplexen wird beschrieben. Lithium‐indolid(12‐Krone‐4) (1) wurde aus Butyllithium, Indol und 12‐Krone‐4 synthetisiert; Natrium‐indolid(15‐Krone‐5) (2) aus Natriummetall, Indol und 15‐Krone‐5; Kalium‐indolid(18‐Krone‐6) (3) aus Kaliumhydrid, Indol und 18‐Krone‐6. Rubidium‐ und Caesium‐indolid(18‐Krone‐6) (4, 5) wurden aus Rb‐ bzw. Cs‐hexamethyldisilazid, Indol und 18‐Krone‐6 erhalten. Die Strukturen von 2, 4 und 5 konnten röntgenographisch bestimmt werden. Die Komplexe 2 und 4 sind einkernig, das Indolid‐Anion weist eine η1(N)‐Koordination zum Metallkation auf. Komplex 5 ist zweikernig mit einem zentralen [Cs—N—]2‐Ring.
A 2D Acentric Coordination Polymer, [Mn(HIDA)2(H2O)2], with a Strong Second‐Order Nonlinear Optical Effect
Authors: Yong Guo‐Ping , Jiang Chao , Wang Zhi‐Yong
Published: October 2003

The crystal structure of [Mn(HIDA)2(H2O)2] (Tetragonal, P4¯21c (no.114), a = b = 8.10(2)Å, c = 9.605(3)Å, α = β = γ = 90°, Z = 2, R = 0.051, wR2 = 0.123 for 460 observed reflections) consists of infinite acentric 2D square grids with HIDA— ions as bridging ligands. The 2D grids are interlocked(along the c axis) by hydrogen bonding. The Mn atoms are octahedrally coordinated by four O atoms of four HIDA— ions (d(Mn—O)= 2.183(4)Å ) and two O atoms of two water molecules (d(Mn—OW) = 2.154(5)Å ). The results show that this acentric coordination polymer exhibits strong powder second harmonic generation (SHG) efficiency, ca. 1.9 times that of potassium dihydrogen phosphate, and remarkable thermal stability.
PCR studies of feline leprosy cases
Authors: Hughes M.S. , James G. , Taylor M.J. , McCarroll J. , Neill S.D. , Chen S.C.A. , Mitchell D.H. , Love D.N. , Malik R.
Published: October 2003

16S rRNA gene sequence analysis provided evidence for two different mycobacterial species, Mycobacterium lepraemurium and a potentially novel species, as causative agents of ‘feline leprosy’. Comparison of 16S rRNA gene sequence data obtained for M. lepraemurium and the potentially novel species indicated 12 nucleotide differences over a 446 bp region encompassing the V2 and V3 hypervariable regions. From available 16S rRNA gene sequence data, M. lepraemurium shared greatest nucleotide identity with M. avium subsp paratuberculosis and M. avium. The novel species had a long helix 18 in the V3 region and shared greatest nucleotide identity with M. leprae, M. haemophilum and M. malmoense. The novel species had an additional ‘A’ nucleotide at position 105 of the aligned 16S rRNA gene sequence, the only other mycobacterial database sequence having this same extra nucleotide being M. leprae. This nucleotide variation was exploited to develop specific PCR assays for the two species. These were found to be effective and specific when tested against a panel of mycobacteria including species found in feline leprosy lesions and closely related mycobacteria and also when applied directly to formalin-fixed, paraffin-embedded tissues from feline leprosy cases.
A view of developing patterns of investment in AMT through empirical taxonomies: new evidence
Authors: Sacristán Dı́az Macarena , Machuca José A.D , Álvarez‐Gil Marı́a José
Published: October 2003

In line with the theoretical premises of the research, the aim of this paper is two‐fold: firstly, to determine whether there are different patterns of advanced manufacturing technology (AMT) investment behavior in the Andalusian aeronautical industry that can be associated with different technology strategies, as in other sectors and geographical areas and, secondly, to identify possible similarities or differences from previous research, such as Boyer et al. [J. Operations Manage. 14 (4) (1996) 297–313] and Jonsson [Int. J. Operations Production Manage. 20 (12) (2000) 1446–1474]. A survey of the 20 plants in the population was conducted via postal questionnaire between July 1999 and April 2001, with a structured interview being held at a later date. A cluster analysis was performed which allowed a taxonomy with three groups of plants to be established: traditionalists, designers and investors. These three groups differ from each other with regard to their AMT investments, industrial activity, size and degree of integration. Differences between the groups in company performance cannot be appreciated. Although the results apparently seem to back up most of the findings of previous works biased to larger companies, they do bring certain aspects into question regarding the explanation for the way the groups are formed. The three critical factors which determine AMT investment in the sector are the company’s being of a certain minimum size, undergoing a period of expansion, and type of activity.
Comparison of two digital radiostereometric analysis methods in the determination of femoral head penetration in a total hip replacement phantom
Authors: Bragdon Charles R. , Estok Daniel M. , Malchau Henrik , Kärrholm Johan , Yuan Xunhua , Bourne Robert , Veldhoven Jean , Harris William H.
Published: October 2003

Radiostereometric analysis (RSA) has been used extensively to evaluate the magnitude and direction of penetration of the femoral head into the acetabular component of a total hip replacement as a result of polyethylene wear and creep. The accuracy and precision of an RSA study depends on several factors, including the radiographic technique, the analytical software, and the positioning of the tantalum markers. This study had three sequential purposes. First, an in vitro phantom model was used to quantify the accuracy and precision of digital images versus conventional radiography in RSA measurements of penetration of the femoral head into the acetabular shell in a total hip replacement. The Umeå RSA software package was used for analysis of both the conventional films, which were digitized at a resolution of 300 DPI, and digital radiographs, which were converted from a DICOM format at a resolution of 218 DPI. Digital radiography was found to be superior. Next, two methods of RSA analysis currently in use for determining femoral head penetration into polyethylene of total joint replacements were compared. Using the phantom model, we compared the Umeå RSA system (Biomedical Innovations AB) to the RSA‐CMS (RSA Clinical Measurement Solution) and in both cases used the digital radiographs. The Umeå RSA system was found to be superior. Finally, two methods of marking the position of the acetabular component with tantalum beads were compared: one in which beads were inserted into previously described towers protruding from the back of the acetabular shell and another in which beads were placed into the peripheral flange of the polyethylene liner using the Umeå RSA analysis system of the digital radiographs. The results using the two marker configurations were similar. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
The structures of BtuCD and MscS and their implications for transporter and channel function
Authors: Bass Randal B , Locher Kaspar P , Borths Elizabeth , Poon Yan , Strop Pavel , Lee Allen , Rees Douglas C
Published: October 2003

The passage of most molecules across biological membranes is mediated by specialized integral membrane proteins known as channels and transporters. Although these transport families encompass a wide range of functions, molecular architectures and mechanisms, there are common elements that must be incorporated within their structures, namely the translocation pathway, ligand specificity elements and regulatory sensors to control the rate of ligand flow across the membrane. This minireview discusses aspects of the structure and mechanism of two bacterial transport systems, the stretch‐activated mechanosensitive channel of small conductance (MscS) and the ATP‐dependent vitamin B12 uptake system (BtuCD), emphasizing their general implications for transporter function.
Inhibition of caffeine biosynthesis in tea (Camellia sinensis) and coffee (Coffea arabica) plants by ribavirin
Authors: Keya Chaman Ara , Crozier Alan , Ashihara Hiroshi
Published: October 2003

The effects of ribavirin, an inhibitor of inosine‐5′‐monophosphate (IMP) dehydrogenase, on [8‐14C]inosine metabolism in tea leaves, coffee leaves and coffee fruits were investigated. Incorporation of radioactivity from [8‐14C]inosine into purine alkaloids, such as theobromine and caffeine, guanine residues of RNA, and CO2 was reduced by ribavirin, while incorporation into nucleotides, including IMP and adenine residues of RNA, was increased. The results indicate that inhibition of IMP dehydrogenase by ribavirin inhibits both caffeine and guanine nucleotide biosynthesis in caffeine‐forming plants. The use of IMP dehydrogenase‐deficient plants as a potential source of good quality caffeine‐deficient tea and coffee plants is discussed.
Coordinate induction of glutathione biosynthesis and glutathione‐metabolizing enzymes is correlated with salt tolerance in tomato
Authors: Mittova Valentina , Theodoulou Frederica L , Kiddle Guy , Gómez Leonardo , Volokita Micha , Tal Moshe , Foyer Christine H , Guy Micha
Published: October 2003

The acclimation of reduced glutathione (GSH) biosynthesis and GSH‐utilizing enzymes to salt stress was studied in two tomato species that differ in stress tolerance. Salt increased GSH content and GSH:GSSG (oxidized glutathione) ratio in oxidative stress‐tolerant Lycopersicon pennellii (Lpa) but not in Lycopersicon esculentum (Lem). These changes were associated with salt‐induced upregulation of γ‐glutamylcysteine synthetase protein, an effect which was prevented by preincubation with buthionine sulfoximine. Salt treatment induced glutathione peroxidase and glutathione‐S‐transferase but not glutathione reductase activities in Lpa. These results suggest a mechanism of coordinate upregulation of synthesis and metabolism of GSH in Lpa, that is absent from Lem.
Ultraviolet radiation‐induced DNA damage in promoter elements inhibits gene expression
Authors: Ghosh Rita , Tummala Ramakumar , Mitchell David L
Published: October 2003

Repair of DNA damage in gene promoters is slower than in actively transcribed genes. Persistent damage in gene promoters though transient can have significant biological effects on regulated gene expression. In this study we investigated the effect of ultraviolet radiation on gene promoter‐associated functions when DNA damage is located within and outside transcription factor binding sites. Our results show that both cyclobutane pyrimidine dimers and (6‐4) photoproducts inhibit DNA–protein interaction, in vitro transcript production and transactivation of reporter genes. The biological significance of transient DNA damage as a mechanism in carcinogenesis is discussed.
Tissue‐specific activity of the proximal human calcitonin receptor promoter is mediated by Sp1 and an epigenetic phenomenon
Authors: Pondel M.D , Partington G.A , Mould R
Published: October 2003

To identify cis‐acting sequences transcriptionally regulating the human calcitonin receptor (hCTR) gene, hCTR promoter/luciferase gene constructs were transiently or stably transfected into hCTR‐positive and ‐negative cell lines. Luciferase assays demonstrated that the proximal hCTR promoter (hCTRP1) was transcriptionally active in all cell lines tested. High‐level hCTRP1 activity depended on an 11 bp Sp1/Sp3 binding site. Electrophoretic mobility shift assay showed that this region bound the transcription factors Sp1 and Sp3. We further showed that hCTRP1 was strongly activated by the 11 bp Sp1/Sp3 binding site in hCTRP1/luciferase‐, Sp1‐transfected Drosophila S2 cells. Bisulphite‐mediated sequencing of genomic DNA from hCTR‐expressing and ‐non‐expressing cell lines demonstrated that the endogenous hCTRP1 was hypomethylated in all cell lines tested. These results suggest that the hCTRP1 is activated by the tissue‐ubiquitous transcription factor Sp1 and that an epigenetic process unrelated to CpG methylation represses its activity in hCTR‐negative tissues.
Cuprous oxidase activity of yeast Fet3p and human ceruloplasmin: implication for function
Authors: Stoj Christopher , Kosman Daniel J
Published: October 2003

The Fet3 protein in Saccharomyces cerevisiae and mammalian ceruloplasmin are multicopper oxidases (MCO) that are required for iron homeostasis via their catalysis of the ferroxidase reaction, 4Fe2++O2+4H+→4Fe3++2H2O. The enzymes may play an essential role in copper homeostasis since they exhibit a strikingly similar kinetic activity towards Cu1+ as substrate. In contrast, laccase, an MCO that exhibits weak activity towards Fe2+, exhibits a similarly weak activity towards Cu1+. Kinetic analyses of the Fet3p reaction demonstrate that the ferroxidase and cuprous oxidase activities are due to the same electron transfer site on the enzyme. These two ferroxidases are fully competent kinetically to play a major role in maintaining the cuprous–cupric redox balance in aerobic organisms.
Coherence resonance and ice ages
Authors: Pelletier Jon D.
Published: October 2003

The processes and feedbacks responsible for the 100‐kyr cycle of Late Pleistocene global climate change are still being debated. This paper presents a numerical model that integrates (1) long‐wavelength outgoing radiation, (2) the ice‐albedo feedback, and (3) lithospheric deflection within the simple conceptual framework of coherence resonance. Coherence resonance is a dynamical process that results in the amplification of internally generated variability at particular periods in a system with bistability and delay feedback. In the Late Pleistocene climate system, bistability results from a combination of long‐wavelength outgoing radiation and the ice‐albedo feedback. These processes are in equilibrium at interglacial and full‐glacial conditions. Delay feedback results from the influence of lithospheric deflection on ice sheet advance and retreat. This process has commonly been represented in numerical climate models by complex models of ice sheet dynamics. As an alternative, the present model incorporates ice sheet dynamics implicitly by using the observed relationship between ice coverage and global temperature. The result is a simple, well‐constrained model for the Late Pleistocene global climate system with only one free parameter. The model accurately reproduces the climate variability recorded in the Vostok ice core from timescales of several thousand to one million years, including the histograms and power‐spectral behavior of the data. The 100‐kyr cycle is a free oscillation in the model, present even in the absence of external forcing. The model also reproduces smaller‐amplitude periodicities at odd harmonics of 100 kyr, suggesting that a significant portion of the spectral power at the Milankovitch bands of 41 and 29 kyr may be internally generated. Finally, the development of 100‐kyr oscillations in the Mid‐Pleistocene may be understood within this model framework as the transition from a climate with one stable state to a system with two stable states brought about by the development of large continental ice sheets and the addition of the ice‐albedo feedback to the climate system.
Meteorological predictions for 2003 Mars Exploration Rover high‐priority landing sites
Authors: Rafkin Scot C. R. , Michaels T. I.
Published: October 2003

The Mars Regional Atmospheric Modeling System is used to predict meteorological conditions that are likely to be encountered by the Mars Exploration Rovers at several proposed landing sites during entry, descent, and landing. Seven areas, five of which contain specific high‐priority landing ellipses, are investigated: Hematite (two sites), Isidis Planitia, Elysium Planitia (two sites), Valles Marineris, and Gusev Crater. The last two locations are in regions of extreme topography, and the local and regional thermal circulations that result are equally extreme. Horizontal wind speeds near the floor of Valles Marineris exceed 50 ms−1. Vertical velocities near the walls exceed 40 ms−1 and penetrate 10 km in altitude above the rim of the canyon. Thermal convection is suppressed within Valles Marineris by subsidence that forms in response to the upslope flows along the canyon walls. Wind magnitudes at Gusev crater are approximately one third of those at the canyon, but horizontal wind shear is greater. Deep convective thermals are noted at the relatively flat Hematite site, where 10 ms−1 updrafts rising to heights of 5 km are not uncommon during the midafternoon. Linearly organized convective updrafts superimposed on upslope circulations dominate over most of Isidis Planitia. Hexagonal and linearly organized convection predominates at Elysium Planitia. Afternoon circulations at all sites pose some risk (significant risk in some cases) to entry, descent, and landing. Most of the atmospheric hazards are not evident in current observational data and general circulation model simulations and can only be ascertained through mesoscale modeling of the region.
An anticyclonic circulation above the Northwest Georgia Rise, Southern Ocean
Authors: Meredith Michael P. , Watkins Jon L. , Murphy Eugene J. , Cunningham Nathan J. , Wood Andrew G. , Korb Rebecca , Whitehouse Mick J. , Thorpe Sally E. , Vivier Frédéric
Published: October 2003

Data from a variety of sources reveal a warm‐core anticyclonic circulation above the Northwest Georgia Rise (NWGR), an ∼2000‐m high bathymetric feature north of South Georgia. The sense of the circulation is opposite to the general cyclonic flow in the Georgia Basin. The circulation shows the characteristics of a stratified Taylor column: dimensional analysis shows that the local bathymetry and hydrography are conducive to the formation of such. ERS2 altimeter data show that the column, whilst not fully permanent, is nonetheless a recurring feature. High concentrations of chlorophyll‐a are observed at the centre of the circulation, indicating that the modulation of the physical environment has significant consequences for the local biogeochemical system via enhanced primary production. Enhanced chlorophyll‐a extends in a long plume from the NWGR along pathways indicated by drifters; this passive redistribution may have consequences for the larger (basin‐) scale ecosystem.
Estimating mean dynamic topography in the tropical Pacific Ocean from gravity and altimetry satellites
Authors: Gourdeau Lionel , Lemoine Jean Michel , Rio Marie Hélène , Hernandez Fabrice
Published: October 2003

A new geoid model, combining the CHAMP satellite gravity data and an accurate altimetric mean sea surface, was used to investigate the 1993–1999 mean dynamic topography in the tropical Pacific Ocean. The mean dynamic topography, represented by a spherical harmonic expansion to degree 60 appear to be consistent with our knowledge of the tropical circulation, notably the South Equatorial Counter Current which is clearly visible in the western Pacific. This satellite solution, validated with in‐situ data, is independent from any climatology and has a resolution similar to other classical mean dynamic topographies. Altimetry combined with geodesy can thus provide an absolute sea level which will be useful for data assimilation and tropical oceanography.
H2 generation in wet grinding of granite and single‐crystal powders and implications for H2 concentration on active faults
Authors: Kameda Jun , Saruwatari Kazuko , Tanaka Hidemi
Published: October 2003

Granite and single crystals of quartz, alkali feldspar, biotite and muscovite are ground in pH‐controlled and pure water solutions using a ball mill at ambient condition to examine the production of H2. The amount of H2 generated by grinding is linearly related with the surface area of ground samples. The slope of the straight line indicates H2 productivity of each mineral: 3.9 × 10−3 μmol/m2 (quartz); 1.0 × 10−3 μmol/m2 (alkali feldspar); 3.6 × 10−2 μmol/m2 (biotite); 2.2 × 10−2 μmol/m2 (muscovite); 4.5 × 10−3 μmol/m2 (granite). High productivity of biotite and muscovite is probably related to the existence of hydroxyls in their crystal structures. Interestingly, H2 production did not depend on the pH of the solution in the case of biotite and granite, while comparisons between fluid acidity and H2 concentration on several active faults suggest that anomalously high H2 is commonly observed at relatively acidic water springs. This correlation may be explained by locally high abundance of phyllosilicates.
A 2.5‐dimensional MHD Alfvén‐wave‐driven solar wind model
Authors: Hu Y. Q. , Li X. , Habbal S. R.
Published: October 2003

A 2.5‐dimensional MHD analysis of Alfvén‐wave‐driven solar wind in the heliospheric meridional plane is presented in order to extend the one‐dimensional model proposed by Weber and Davis [1967] to the two‐dimensional case. In our model, no energy input is applied to the helmet streamer, while the solar wind along open field lines is assumed to be driven by Alfvén waves. The differential rotation of the Sun is considered. The numerical results obtained essentially match relevant Ulysses observations and give the spatial distribution of the azimuthal components of the flow velocity and magnetic field. The effect of the existence of these azimuthal components on the global properties of the solar wind is found to be negligible, and the loss rate of the angular momentum of the Sun due to the solar wind is estimated.
A global view of the molecular oxygen night airglow
Authors: Hays Paul B. , Kafkalidis Julie F. , Skinner Wilbert R. , Roble Raymond G.
Published: October 2003

The High‐Resolution Doppler Imager on the Upper Atmosphere Research Satellite has observed the O2 atmospheric band nightglow at extremely high spatial resolution of 50 km in the horizontal over much of Earth's surface. These observations of the oxygen nightglow are shown to be a good surrogate for atomic oxygen outflow from the thermosphere and subsequent recombination in the upper mesosphere. The distribution of enhanced airglow and recombination verify the previous observations that bright regions of the nightglow are associated with descending motion, where the tides are transporting atomic oxygen out of the thermosphere, and regions of decreased airglow are associated with ascending tidal motion. The detailed observations of the global airglow at a scale of 100 km present a much more complex picture, however. The tidally enhanced regions are extremely structured, with strong longitudinal and latitudinal variability in brightness and associated atomic oxygen recombination. These structured regions are persistent on a timescale of a day or more, with certain regions of the globe exhibiting enhanced airglow much of the time. These regions are present over the entire night side of the globe but are strongly modulated by the ascending and descending tidal motions. A theoretical study of these enhancements suggests that they are caused by the upward propagation of gravity waves, which break in the high mesosphere and induce strong vertical motion in the atmosphere. It is interesting that the primary cause of the increased transport of atomic oxygen is vertical motion rather than the conventional enhanced turbulence explanation. These gravity waves are associated with wind shear and strong convective activity in the troposphere and often appear in certain preferred locations where convective activity is expected. These observations have important implications for the basic processes by which momentum and energy are deposited in the upper mesosphere. We suggest that the processes must be modeled as stochastic events that dance around the base of the thermosphere, generally in climatologically preferred regions, rather than the relatively uniform distribution of gravity wave forcings that is being used in general circulation models up to this time.
Solar extreme ultraviolet variability of the X‐class flare on 21 April 2002 and the terrestrial photoelectron response
Authors: Woods Thomas N. , Bailey Scott M. , Peterson W. K. , Solomon Stanley C. , Warren Harry P. , Eparvier Francis G. , Garcia Howard , Carlson Charles W. , McFadden James P.
Published: October 2003

The near‐simultaneous observations of the solar extreme ultraviolet (EUV) irradiance and terrestrial photoelectron distribution during and after the X‐class flare on 21 April 2002 provide for a distinctive study of the effects that a solar flare can have on Earth's upper atmosphere. The solar EUV irradiance from 0.1 to 195 nm was measured by the Solar EUV Experiment (SEE) aboard the NASA Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED) satellite. The terrestrial photoelectron distribution from 10 to 1000 eV was measured by the Fast Auroral Snapshot (FAST) energetic electron sensor. The variations of the solar EUV irradiance from the X‐class flare at ∼0200 UT on 21 April 2002 range from more than a factor of 10 for the X‐ray emissions to less than 10% at longer EUV wavelengths. The measured ratio of the flare spectrum to the preflare spectrum has a spectral shape that is similar to that predicted for the Bastille Day 2000 flare. Most of the solar irradiance variation is in the X‐ray range and is due to coronal emissions. The photoelectron distribution changed by a factor of about 10 for the high‐energy Auger electrons and by very little for the low‐energy electrons. Modeling the photoelectron distribution using the measured solar EUV irradiance provides results that are qualitatively consistent with the observed photoelectron distribution. This study is focused primarily on the relative changes during the flare compared to the preflare conditions.
From Research Model to Forecasting Tool
Authors: Simpson Sarah
Published: October 2003

Many experts agree that current capabilities for anticipating space storms trail atmospheric weather forecasting by 40 years or more. Improving space weather predictions could help avoid costly damage to critical communication and navigation satellites and power grids. Progress in the United States, though, has long been impeded by the lack of a comprehensive way to shift promising space weather simulations from the hands of researchers and developers to operators. Until recently, such transitions could take years. Dramatically cutting that transition time is one of the ways the new Community Coordinated Modeling Center (CCMC) is living up to its name. The CCMC involves branches of the U.S. Department of Defense, NASA, NOAA, and the National Science Foundation.
Connecting the World's Space Agencies
Authors: Simpson Sarah
Published: October 2003

The new International Living With a Star (ILWS) initiative that is supervised by a seven‐member steering committee representing the main space agencies from Canada, Europe, Japan, Russia, and the United States, currently involves 24 space organizations worldwide. The mission of the fledgling program is to stimulate, strengthen, and coordinate space research in order to understand the governing processes of the connected Sun‐Earth system as an integrated entity. Over the next decade, ILWS will assemble the largest fleet of spacecraft ever focused on a single scientific objective.
Value of irrigation water with uncertain future rain: A simulation case study of sugarcane irrigation in northern Australia
Authors: Stoeckl N. , Inman‐Bamber N. G.
Published: October 2003

Using sugarcane as a case study, this paper shows how an agronomic model can be used to estimate the marginal value of stored irrigation water with uncertain future rain. We do this by estimating production functions that have the water available for use as the variable factor of production (referring to them as allocation production functions). These differ from more “traditional” production functions which use the water actually applied as the variable factor of production (referred to here as irrigation production functions). We note that the amount of water actually applied is jointly determined by the amount of water that is available and by rainfall. Hence imperfect information vis‐à‐vis future rain means that irrigation water may be overvalued if the difference between the water available for use and the water actually used is not considered. We use results from simulations of sugarcane irrigation in northern Australia to demonstrate the potential magnitude of this overvaluation, and to examine the “value” of prepurchased irrigation water in various circumstances.
A nonparametric model for stochastic generation of daily rainfall occurrence
Authors: Harrold Timothy I. , Sharma Ashish , Sheather Simon J.
Published: October 2003

This paper presents a nonparametric model for generating single‐site daily rainfall occurrence. The model is formulated to reproduce longer‐term variability and low‐frequency features such as drought and sustained wet periods, while still reproducing characteristics at daily time scales. Parsimony is achieved within a Markovian framework by using “aggregate” predictor variables that describe how wet it has been over a period of time. The use of a moving window to give a seasonally representative sample at any given time of year ensures an accurate representation of the seasonal variations present in the rainfall time series. Actual simulation proceeds by resampling from the historical record of rainfall occurrence, conditional to the current values of the associated predictors. The model is applied using historical daily rainfall occurrence from Sydney, Australia. We find that the use of multiple predictors specified at a daily level and at seasonal, annual, and multiyear aggregation levels leads to sequences that more closely reproduce the longer‐term variability present in the historic records, compared to sequences produced by models incorporating only one or two predictors.
Severe recurrent cytomegalovirus disease revealed by a colocutaneous fistula in a kidney transplant recipient
Authors: Dumoulin A. , Boulmerka H. , Tran Van Nhieu J. , Lang P. , Baron C.
Published: October 2003

Abstract: Intestinal disorders are classical complications of cytomegalovirus (CMV) infection in kidney transplant recipients (Helderman JH, Goral S. Gastrointestinal complications of transplant immunosuppression. J Am Soc Nephrol 2002: 13: 277–287). Severe ulcerative colitis that is sometimes lethal has been reported (Foucar E, Mukai K, Foucar K, Sutherland DE, Van Buren CT. Colon ulceration in lethal cytomegalovirus infection. Am J Clin Pathol 1981: 76: 788–801 and Frankel AH, Barker F, Williams G, Benjamin IS, Lechler R, Rees AJ. Neutropenic enterocolitis in a renal transplant patient. Transplantation 1991: 52: 913–914). The immunosuppressive drugs currently used, and notably mycophenolate mofetil (Cellcept®), cause significant changes in the incidence, duration, and viral load of CMV infections with severe atypical forms of CMV disease (De Maar EF, Verschuuren EA, Homan vd Heide JJ, et al. Effects of changing immunosuppressive regimen on the incidence, duration and viral load of cytomegalovirus infection in renal transplantation: a single center report. Transpl Infect Dis 2002: 4: 17–24 and Perez Valentin MA, Cofan F, Sole M, et al. Atypical cytomegalovirus in renal transplantation: a new form of presentation. Nefrologia 2002: 22: 381–385). This report describes a patient who suffered from several episodes of colitis due to an unusual and late‐appearing CMV infection.
Successful treatment of Staphylococcus aureus bacterial endocarditis in a renal transplant recipient
Authors: D'Cunha P.T. , Davenport D.S. , Fisher K.A.
Published: October 2003

We report the successful treatment of Staphylococcus aureus endocarditis in a renal transplant recipient with preservation of his renal allograft. A 44‐year‐old man presented to the emergency room with sudden onset of fevers and rigors 7 weeks after renal transplantation. Infective endocarditis was diagnosed by Duke's Criteria (Durack et al. New criteria for the diagnosis of infective endocarditis. Am J Med 1994: 96: 200–209) with multiple positive blood cultures for S. aureus and a mitral valve vegetation on transesophageal echocardiogram. He was treated with intravenous antibiotics for 6 weeks with continuation of his immunosuppression. He has remained clinically stable for over 5 years. Although the treatment of S. aureus endocarditis in immunosuppressed transplant patients has traditionally resulted in loss of their allograft, prompt diagnosis and appropriate antibiotics with continued immunosuppressive therapy resulted in a successful outcome and allograft preservation in this case.
Disseminated Mycobacterium gordonae infection in a renal transplant recipient
Authors: Den Broeder A.A. , Vervoort G. , Van Assen S. , Verduyn Lunel F. , De Lange W.C. , De Sévaux R.G.L.
Published: October 2003

Abstract: The use of more intensive immunosuppressive regimens and the increasing number of patients that are exposed to immunosuppressive strategies in transplantation medicine have changed the spectrum of infections that is encountered by the clinician. We describe a 62‐year‐old female renal transplant recipient receiving immunosuppressive therapy who developed complaints of weight loss, diarrhoea, cough, and fever. Increased C‐reactive protein and pancytopenia were found. The presence of Mycobacterium gordonae, a non‐tuberculous mycobacterium, was eventually demonstrated in bronchoalveolar lavage fluid, bone marrow, spleen, and liver. Determination of the pathogen was accelerated using a Line Probe Assay, a reverse hybridisation technique using an RNA fragment specific for different mycobacterium species. Treatment was initiated using a combination of clarithromycin, ethambutol, and rifampicin. The initial response to treatment was good, but splenectomy and change of immunosuppressive and antimycobacterial therapy were necessary for long‐term control of the infection. Problems in the diagnosis and treatment of this uncommon pathogen are discussed.
Retrospective evaluation of the risk of hepatitis B virus reactivation after transplantation
Authors: Duhart B.T. , Honaker M.R. , Shokouh‐Amiri M.H. , Riely C.A. , Vera S.R. , Taylor S.L. , Al‐jedai A.H. , Gaber A.O.
Published: October 2003

Abstract: Numerous case reports describe patients with previously documented immunity developing active hepatitis B virus (HBV) infection after transplantation. However, the risk of reactivation of HBV under long‐term immunosuppression in hepatitis B core antibody (HBcAb)‐positive, hepatitis B surface antigen (HBsAg)‐negative transplant recipients has not been clearly described. Herein, we present a long‐term follow‐up for 49 HBcAb‐positive, HBsAg‐negative recipients (27 liver, 18 kidney, 4 pancreas) transplanted between June 1996 and April 2001. Among these, 37 recipients (76%) were HBsAb positive at transplantation. Immunosuppression consisted of various antibody induction regimens in 20 (41%) of the recipients with either tacrolimus (33 [67%])‐ or cyclosporine (16 [33%])‐based maintenance immunosuppression. The incidence and duration of HBV prophylaxis was not significant. No patient received hepatitis B immunoglobulin (HBIG) before or after transplantation. Additionally, only two patients received lamivudine, which was started post transplant without clinical indication. The mean length of follow‐up was 3.1±1.4 years. At the last follow‐up, overall patient and graft survival were 98% and 96%, respectively. Patient survival was 96% in liver, 100% in kidney, and 100% in pancreas transplant recipients. The graft survival for each organ type was 93% in liver, 100% in kidney, and 75% in pancreas transplant recipients at the end of follow‐up. There was no incidence of HBV reactivation defined as recurrence of HBsAg and/or HBV DNA positivity. These data suggest that the risk of reactivation of HBV in HBcAb‐positive, HBsAg‐negative transplant recipients under immunosuppression is negligible, regardless of immunosuppressive regimen, lamivudine prophylaxis, or HBsAb status. These patients should have access to transplantation as they enjoy excellent patient and graft survival rates.
Pulmonary involvement during cytomegalovirus infection in immunosuppressed patients
Authors: De Maar E.F. , Verschuuren E.A.M. , Harmsen M.C. , The T.H. , Van Son W.J.
Published: October 2003

Abstract: Although cytomegalovirus (CMV) pulmonary involvement after solid organ transplantation is infrequently seen nowadays, CMV pneumonitis is still a potential lethal complication. Introduction of the pp65 antigenemia assay enabled early and rapid diagnosis of CMV viremia in transplant patients prior to symptoms. Also, in asymptomatic patients with CMV viremia, a decreased pulmonary diffusion capacity could be demonstrated. In this review, we discuss clinical and subclinical pulmonary involvement of CMV infection in the immunocompromised host with an emphasis on transplant recipients. The clinical course, diagnosis, therapy, prophylaxis, and pathophysiology of CMV pneumonitis are discussed.
Linezolid in the treatment of vancomycin‐resistant Enterococcus faecium in solid organ transplant recipients: report of a multicenter compassionate‐use trial
Authors: El Khoury J. , Fishman J.A.
Published: October 2003

Abstract: Vancomycin‐resistant Enterococcus faecium (VRE) is increasing in incidence in solid organ transplant recipients and has a high (up to 83%) associated mortality rate. Until recently, there have been no consistently effective antimicrobial therapies for VRE infection. Linezolid is a new antibiotic that belongs to the class of oxazolidinones approved by the FDA for the treatment of VRE infections, including those with bacteremia. Here, we report the experience with linezolid in an open‐label, compassionate‐use trial at 53 US centers for the treatment of documented VRE infections in patients with solid organ transplants. Eighty‐five patients with solid organ transplants and documented VRE infections were studied. Blood cultures were positive for VRE in 43 patients, while 42 patients had other, non‐rectal, sites of infection. Fifty‐three patients responded well to treatment, with clinical resolution of the infection (62.4% survival rate). Of these, 47 had documented negative cultures post therapy. The mean duration of therapy for cured patients was 23.5 days. Thirty‐two (37.6%) patients died, 28 due to sepsis and organ failure (32.9% failure rate), and 4 due to unrelated causes. Mortality rates for patients with bacteremia were comparable to mortality rates observed with patients who had positive cultures from other sites. Adverse reactions to linezolid included thrombocytopenia (4.7%), decreased leukocyte count (3.5%), and an increase in blood pressure (1.2%), none of which led to discontinuation of therapy. Linezolid appears to be a safe and effective treatment option for VRE, even in the presence of bacteremia, and may lead to decreased mortality in solid organ transplant recipients with VRE infection.