bluuebunny/crossref_metadata_2025 huggingface dataset:
Foreign body aspiration: clinical utility of flexible bronchoscopy
Authors: Dikensoy O , Usalan C , Filiz A
Published: July 2002

Foreign body aspiration is a worldwide health problem which often results in life threatening complications. More than two thirds of foreign body aspirations occur among children younger than 3 years. Organic materials such as nuts, seeds, and bones are most commonly aspirated. There is a wide range of clinical presentation, and often there is not a reliable witness to supply the clinical history, especially in children. Maintaining a high index of suspicion is therefore necessary for the diagnosis. None of the imaging methods employed in such cases are diagnostic, and bronchoscopy is frequently necessary for the diagnosis as well as the treatment. In adults, removal of the foreign body can be attempted during diagnostic examination with a fibreoptic bronchoscope under local anaesthesia, which may help to avoid any further invasive procedures with more complications. When diagnosis is delayed, complications of a retained foreign body such as unresolving pneumonia, lung abscess, recurrent haemoptysis, and bronchiectasis may necessitate a surgical resection. However, some of the late complications may resolve completely after the retrieval of the foreign body, therefore, a preoperative flexible bronchoscopy should always be considered in suitable cases.
Fatigue in cholestatic liver disease—a perplexing symptom
Authors: Kumar D , Tandon R K
Published: July 2002

Fatigue is an important symptom and a quality of life determinant in patients with cholestatic liver disease. The pathogenesis of fatigue is obscure, although alterations in central neurotransmission and peripheral muscle dysfunction have been incriminated. No effective treatment is available at present. The available literature on fatigue in cholestatic liver disease is reviewed.
β-Tubulin and histoneH3gene sequences distinguishCryphonectria cubensisfrom South Africa, Asia, and South America
Authors: Myburg Henrietta , Gryzenhout Marieka , Wingfield Brenda D , Wingfield Michael J
Published: July 2002

Cryphonectria cubensis (Bruner) Hodges is the causal agent of an important stem canker disease of Eucalyptus. Previous phylogenetic studies based on sequence data have shown that C. cubensis is distinct from other species of Cryphonectria but that C. cubensis isolates reside in two distinct groups, consistent with geographical origin. Thus, isolates of C. cubensis from South America and South Africa grouped together but apart from those originating from Southeast Asia and Australia. These results were in contrast with the symptoms of Cryphonectria canker in South Africa, which are different from those observed elsewhere in the world. The aim of this study was to use more variable regions of the fungal genome to test whether South African isolates of C. cubensis are genetically distinct from those from other parts of the world. For this comparison, β-tubulin and histone H3 gene sequences were used. Specimens from South America, Southeast Asia, Australia, and South Africa were also compared morphologically. The phylogram emerging from the analysis indicated that South American and Southeast Asian  Australian isolates resided in two well-resolved but closely related clades. However, isolates from South Africa were distinct from other groups. This is consistent with ecological aspects of the South African fungus, although no obvious morphological differences between the fungi from the various regions could be found. Our results suggest that the South African fungus represents a species distinct from C. cubensis occurring elsewhere in the world.Key words: β-tubulin, histone H3, molecular phylogeny, Cryphonectria cubensis.
A gravity profile across southern Saganash Lake fault: implications for the origin of the Kapuskasing Structural Zone
Authors: Nitescu B , Halls H C
Published: July 2002

A high-resolution gravity profile, with station elevations and locations determined by a differential Global Positioning System, shows that the Saganash Lake fault that defines the northwestern boundary of the southern Kapuskasing Structural Zone (KSZ) is southeast dipping and of reverse type. Previous interpretations of a normal fault, caused by crustal collapse following east-verging thrusting along the Ivanhoe Lake fault that forms the southeastern boundary of the KSZ are no longer tenable. Instead, the reverse nature of the Saganash Lake fault is more in harmony with a model of the Kapuskasing zone, whereby its fault-bounded, uplifted blocks are positive flower structures formed by dextral shear along a zone of left-stepping en echelon faults.
Variation in plagioclase clouding intensity in Matachewan dykes: evidence for the exhumation history of the northern margin of the Sudbury Igneous Complex
Authors: Siddorn J P , Halls H C
Published: July 2002

Early Proterozoic Matachewan mafic dykes that cut the Archean Cartier granite  Levack Gneiss Complex north of the Sudbury Igneous Complex (SIC), Canada, are generally metamorphosed to lower amphibolite facies but exhibit locally unaltered plagioclase. These plagioclase feldspars display a clouding similar to that found in the same swarm in the vicinity of the Kapuskasing uplift, about 200 km to the northwest, where the clouding intensity is due to magnetite exsolution and displays a positive correlation with the depth of dyke emplacement. In the Sudbury area, the clouding intensity, obtained by image analysis of thin sections, increases away from the SIC, opposite to the direction of increasing regional metamorphism in the Archean basement. This suggests that the Levack Gneiss Complex north of the SIC was exhumed prior to the intrusion of 2.47 Ga Matachewan dykes and therefore predates the formation of the SIC and associated impact event. The southward tilting of the crust inferred from the plagioclase-clouding data appears to have involved uplift along the Benny Deformation Zone, but the exact age of this deformation is unknown. It may be associated with the 1.81.9 Penokean Orogen, 1.85 Ga Sudbury impact crater, or 2.22.4 Ga Blezardian Orogen.
The southeastern Churchill Province: synthesis of a Paleoproterozoic transpressional orogen
Authors: Wardle Richard J , James Donald T , Scott David J , Hall Jeremy
Published: July 2002

The Paleoproterozoic southeastern Churchill Province (SECP) is located in the northeastern Canadian Shield of Labrador and Quebec. The SECP formed through the oblique collisions of the Archean Nain and Superior cratons with a third intervening Archean block, the core zone. The belt has a tripartite structure, comprising the Torngat Orogen (TO) formed by Nain craton  core zone collision in the east, the core zone in the centre, and the New Quebec Orogen (NQO) formed by Superior craton  core zone collision in the west. The SECP thus records transpressional development on the flanks of the Superior and Nain cratons as they indented northwards to form the larger Trans-Hudson  Nagssugtoqidian orogenic belt to the north. Principal stages of tectonic development were (1) 2.22.1 Ga crustal rifting of Nain and Superior cratons; (2) ca. 1.9 Ga subduction under eastern Nain craton; (3) ca. 1.871.85 Ga collision of Nain craton and core zone to form the TO; (4) 1.8451.820 Ga sinistral transpression in the TO, and subduction under the western core zone; and (5) 1.821.77 Ga collision of Superior craton and core zone to form the NQO, in association with dextral transpression. Crustal-scale cross sections of the SECP have been developed from reflection and refraction seismic data. The western part of the NQO is dominantly west-vergent and associated with an imbricate thick-skinned thrust stack that ramps from the base of the crust. The core zone is characterized by a 3540 km thick crust and pervasive east-dipping fabrics related to westerly thrusting. The TO is a narrow, doubly vergent belt, associated with a 48 km thick crust that forms a crustal root with a Moho relief of 12 km. The root is interpreted to result from attempted subduction of the core zone under the Nain craton, possibly as a result of mid-crustal wedging by the Nain craton. The TO was the site of intense convergence that resulted in excision of juvenile crust, possibly including tectonic removal of the axial magmatic arc. As a result, the middle to lower levels of the SECP consist largely of refractory Archean lithosphere. This may account for the lack of widespread post-collisional plutonism in the SECP and the preservation of the TO root.
Mesoproterozoic lamprophyres in the Labrieville Massif, Quebec: clues to the origin of alkalic anorthosites?
Authors: Owens Brent E , Tomascak Paul B
Published: July 2002

Mesoproterozoic lamprophyre dikes occur at four localities within the ~1010 Ma Labrieville anorthosite in the Grenville Province of southern Quebec. All dikes are thin (<20 cm wide), oriented ~N57W, and steeply dipping. Three are biotite lamprophyres, but the fourth is dominated by amphibole. Laser total-fusion 40Ar/39Ar analyses on amphibole or biotite yield minimum ages for the dikes of 945.5 ± 8 Ma, 907.0 ± 5.9 Ma, 892.0 ± 6.2 Ma, and 889.2 ± 9.8 Ma. A crystallization age of ~1 Ga for all dikes is consistent with these data and RbSr isotopic systematics. All lamprophyres contain high levels of Cr (284393 ppm), Ni (101180 ppm), Ba (13805580 ppm), Sr (23593109 ppm), and rare-earth elements (REE; LaN = 191288), with average LaN/LuN = 26 and no Eu-anomalies. At 1 Ga, all lamprophyres have a similar initial Sr isotopic ratio of ~0.7034, similar to Bulk Earth. In contrast, εNd values vary considerably from 4 to 10.2, indicating sources with variable long-term light-REE enrichment. Negative correlations between 143Nd/144Nd and La/Nb and K suggest involvement of at least two source components, probably asthenosphere and metasomatized subcontinental lithosphere. The lamprophyres are only slightly younger than ~1010 Ma Labrieville massif, which is also alkalic and enriched in Sr and Ba relative to most other anorthosites. The lamprophyres provide unequivocal evidence for a Sr- and Ba-rich component in the lithospheric mantle that may have contributed to the parental magmas of Labrieville and other andesine anorthosites in this part of Quebec.
U–Pb geochronologic constraints on the crustal evolution of the Long Range Inlier, Newfoundland
Authors: Heaman L M , Erdmer Philippe , Owen J V
Published: July 2002

The Long Range Mountains of Newfoundland expose the northeastern most basement inlier of the Appalachian Orogen. UPb results for two samples of basement gneiss reveal crustal formation ages of 1466 ± 10 Ma (Western Brook Pond charnockite) and 1530 ± 8 Ma (Cat Arm Road gneiss), indicating an affinity with Pinwarian magmatism (15101450 Ma) in Labrador. A third sample of basement gneiss from the Cat Arm Road dam site yielded a minimum formation age of 1631 Ma. These basement gneisses were intruded by granite plutons during two periods of Grenvillian magmatism; Group I at 10321022 Ma and Group II at 993985 Ma. Group I intrusions include the 1032.0 ± 1.5 Ma Lomond River granite and the 1022.0 ± 2.0 Ma Lake Michel igneous suite; Group II intrusions include the 999 ± 4 Ma Potato Hill charnockite, 993 ± 7 Ma Horse Chops granite, 984.9 ± 1.6 Ma Cloud River granite, and may include the Apsy granite. The metamorphic history of the Long Range Inlier is complex and three discrete Proterozoic metamorphic events can be delineated on the basis of field relationships and UPb dates for metamorphic minerals. M1 metamorphism is a regional high-grade event that occurred prior to 1032 Ma, the emplacement age for the unmetamorphosed Lomond River granite. M2 and M3 occurred at 1022 and 989 Ma, respectively; coinciding with the two main periods of Grenvillian magmatism. The Precambrian crustal evolution of the Long Range Inlier is very similar to the Pinware terrane of Labrador, consistent with a single contiguous terrane presently separated by the Gulf of St. Lawrence. A surprising discovery from this study is identification of the first known occurrence of Silurian mafic magmatism in the Long Range Inlier, the 430.5 ± 2.5 Ma Taylor Brook gabbro.
Vorticity and circulation: spatial metrics for evaluating flow complexity in stream habitats
Authors: Crowder David W , Diplas Panayiotis
Published: July 2002

Channel topography, formed by boulders, submerged bars, and meanders, creates complex flow patterns. These flow patterns exist over a variety of spatial scales and provide habitat for many aquatic organisms. Spatial flow features cannot be adequately characterized with qualitative descriptions or hydraulic metrics such as depth and velocity. Two-dimensional hydraulic model simulations, based on detailed channel geometry, are used to develop and test vorticity (a point metric) and a circulation-based metric (an area metric) as means of quantifying spatial flows occurring within micro-, meso-, and macro-habitat features. The proposed spatial metrics are computed throughout distinctly different regions of a study site. The vorticity metric produces small absolute values in uniform flows and large absolute values in complex flows. Circulation metric values varied by a factor of 11.7 within distinctly different regions of the modeled study site and suggest that the metric provides a means of quantifying flow complexity within a study reach or within individual mesoscale habitats such as pools, eddies, riffles, and transverse flows. The circulation metric is used to quantify flow complexity around three brown trout (Salmo trutta) redds to provide an example of how the proposed metric might be employed in habitat studies.
Gamma-ray transmission technique for quality control of coal seams
Authors: Sekhar N R , Reddy SV SR , Rao A SN
Published: July 2002

The useful heat value (UHV) that is the figure of merit for coal depends on various parameters such as fixed carbon, volatiles, ash, and moisture. The percentage of these materials present in a given sample of coal can be estimated by gamma-ray transmission studies. Using gamma rays of energies 30.85 and 81.0 keV, coal samples were studied and the relationships between attenuation coefficients and known UHV and ash contents were obtained. These relationships can be used to measure UHV/ash values for other samples using this simple, fast, and reliable nondestructive method.

PACS No.: 32.80
Studies for the Odin sub-millimetre radiometer: III. Performance simulations
Authors: Merino F , Murtagh D P , Ridal M , Eriksson P , Baron P , Ricaud P , Noë J de la
Published: July 2002

Odin is a small, low-cost satellite with a combined astronomical and aeronomical mission. The mission is divided on an equal basis between astronomy and aeronomy. The aeronomy objectives can be divided into four main subjects: stratospheric ozone chemistry, mesospheric ozone chemistry, the summer mesopause region, and the coupling between atmospheric regions. The primary instrument on Odin is the millimetre and sub-millimetre radiometer (SMR), which is used both for astronomy and aeronomy. It is the first satellite to use sub-millimetre frequencies for limb-sounding mode. Odin is also equipped with an optical spectrometer (OSIRIS). This paper is the third of a three-part series and describes the choices of observing modes and the expected performance of the SMR instrument for the aeronomy mission. The relevant frequencies are identified and the exact selection of lines is made. This is followed by a detailed simulation study to determine the achievable altitude coverage together with the corresponding vertical resolution for each retrievable species. An indication of the expected uncertainties is also given, showing, for example, a high-sensitivity to mesospheric water vapour and stratospheric chlorine monoxide. However, a complete analysis of observation uncertainties must await launch and the completion of the validation programme.

PACS Nos.: 42.68A, 07.07D, 07.57K
Selective biotransformation of substituted alicyclic nitriles by Rhodococcus equi A4
Authors: Martínková Ludmila , Klempier Norbert , Preiml Margit , Ovesná Mária , Kuzma Marek , Mylerová Veronika , Kren Vladimír
Published: July 2002

Nitrile hydratase from Rhodococcus equi A4 discriminated between geometric isomers of substituted alicyclic nitriles. The enzyme transformed trans-4-benzoyloxycyclohexanecarbonitrile (trans-1a), cis-3-benzoyloxy cyclohexanecarbonitrile (cis-2a), trans-2-hydroxycyclohexanecarbonitrile (trans-3a), and trans-2-hydroxycyclo pentanecarbonitrile (trans-4a) into the corresponding amides. On the contrary, cis-2-hydroxycyclohexanecarbonitrile (cis-3a) and cis-2-hydroxycyclopentanecarbonitrile (cis-4a) were not converted to a significant extent. cis-4-Ben zoyl oxycyclohexanecarbonitrile (cis-1a) was also a substrate of the enzyme but reacted slowly. Diequatorial arrangement of the substituents in trans-1a, cis-2a, and trans-3a appears to positively influence the activity of the nitrile hydratase.
Enantioselective enzymatic aminolysis of a racemic 2-isoxazolylacetate alkyl ester
Authors: Sigmund Amy E , McNulty Kenneth C , Nguyen Dzuy , Silverman Charlotte E , Ma Philip , Pesti Jaan A , DiCosimo Robert
Published: July 2002

Pseudomonas cepacia lipase or Candida antartica lipase B catalyzes the enantioselective aminolysis of a racemic 2-isoxazolylacetate alkyl ester, isobutyl 2-[3-(4-cyanophenyl)-4,5-dihydro-5-isoxazolyl]acetate, by 3-amino-N-(butoxycarbonyl)-L-alanine methyl ester, mono(4-methylbenzenesulfonate) to produce the corresponding amide, (R)-methyl-3-[[[3-(4-cyanophenyl)-4,5-dihydro-5-isoxazolyl]acetyl]amino]-N-(butoxycarbonyl)-L-alanine, which is an intermediate in the preparation of an isoxazoline-based platelet glycoprotein IIb/IIIa antagonist. Key words: enantioselective aminolysis, Pseudomonas cepacia lipase, Candida antartica lipase B.
Selective reduction and chemical modification of oxidized lipase cysteine mutants
Authors: Hedin Eva MK , Patkar Shamkant A , Vind Jesper , Svendsen Allan , Hult Karl , Berglund Per
Published: July 2002

Thirteen single-cysteine mutants of the 33 kDa fungal triacylglycerol lipase Thermomyces (formerly Humicola) lanuginosa lipase (TLL, EC 3.1.1.3) were produced and characterized for the purpose of site-directed chemical modification with spectroscopic reporter groups. All cysteine mutants were found to be predominantly blocked by oxidation to disulfides with endogenous cysteine during production. The fraction of lipase molecules with free sulfhydryl groups was analyzed by labeling with N-biotinylaminoethyl methanethiosulfonate, followed by a novel dot-blot method based on biotin-streptavidin interactions. A non-invasive method for the reduction of the introduced cysteine was elaborated for this protein containing three native disulfide bridges. The site-specifically reduced TLL mutants were then labeled with the sulfhydryl-specific reagents 2-(5-dimethylaminonaphth-1-ylsulfonamido)ethyl methanethiosulfonate or (1-oxyl-2,2,5,5-tetramethyl-Δ3-pyrroline-3-methyl) methanethiosulfonate, and studied by fluorescence and electron spin resonance (ESR) spectroscopy.Key words: lipase, cysteine mutant, selective reduction, chemical modification, methanethiosulfonate.
Dioxygenase-catalyzed cis-dihydroxylation of pyridine-ring systems
Authors: Boyd Derek R , Sharma Narain D , Modyanova Ludmila V , Carroll Jonathan G , Malone John F , Allen Christopher CR , Hamilton John TG , Gibson David T , Parales Rebecca E , Dalton Howard
Published: July 2002

Toluene dioxygenase-catalyzed dihydroxylation, in the carbocyclic rings of quinoline, 2-chloroquinoline, 2-methoxyquinoline, and 3-bromoquinoline, was found to yield the corresponding enantiopure cis-5,6- and -7,8-dihy dro diol metabolites using whole cells of Pseudomonas putida UV4. cis-Dihydroxylation at the 3,4-bond of 2-chloroquino line, 2-methoxyquinoline, and 2-quinolone was also found to yield the heterocyclic cis-dihydrodiol metabolite, (+)-cis-(3S,4S)-3,4-dihydroxy-3,4-dihydro-2-quinolone. Heterocyclic cis-dihydrodiol metabolites, resulting from dihydroxylation at the 5,6- and 3,4-bonds of 1-methyl 2-pyridone, were isolated from bacteria containing toluene, naphthalene, and biphenyl dioxygenases. The enantiomeric excess (ee) values (>98%) and the absolute configurations of the carbocyclic cis-dihydrodiol metabolites of quinoline substrates (benzylic R) and of the heterocyclic cis-diols from quinoline, 2-quinolone, and 2-pyridone substrates (allylic S) were found to be in accord with earlier models for dioxygenase-catalyzed cis-dihydroxylation of carbocyclic arenes. Evidence favouring the dioxygenase-catalyzed cis-dihydroxylation of pyridine-ring systems is presented.Key words: dioxygenases; cis-dihydroxylation, pyridines, 2-pyridones, absolute configurations.
Peptide model XXVIII: An exploratory ab initio and density functional study on the side-chain-backbone interaction in N-acetyl-L-cysteine- N-methylamide and N-formyl-L-cysteinamide in their γL-backbone conformations
Authors: Zamora M A , Baldoni H A , Rodriguez A M , Enriz R D , Sosa C P , Perczel A , Kucsman A , Farkas O , Deretey E , Vank J C , Csizmadia I G
Published: July 2002

A conformational and electronic study on the energetically preferred conformations (γL) of N- and C-protected L-cysteine (P-CONH-CH(CH2SH)-CONH-Q, where P and Q may be H or Me) was carried out. After restraining the backbone (BB) conformation to its global minimum (γL or C7eq), all nine possible side-chain (SC) conformations were subjected to geometry optimization at the HF/321G and the B3LYP/631G(d,p) levels of theory. Seven of the nine side-chain conformers were located on the potential-energy surface. All conformers were subjected to an AIM (atoms in molecules) analysis. This study indicates that three of the seven optimized conformers exhibited either or both SC [Formula: see text] BB- or BB [Formula: see text] SC-type intramolecular hydrogen bonding. Five conformers, however, had distances between a proton and a heteroatom that suggested hydrogen bonding.Key words: L-cysteine diamides, side-chain potential-energy surface, ab initio and DFT geometry optimization, AIM analysis, intramolecular hydrogen bonding.
A partial-molar volume study of electrolytes in propylene carbonate-based lithium battery electrolyte solutions at 298.15 K
Authors: Wang Jianji , Zhao Yang , Zhuo Kelei , Lin Ruisen
Published: July 2002

Apparent molar volumes (V2, ϕ ) and standard partial-molar volumes (V20, ϕ ) of LiClO4 and LiBr at 298.15 K have been determined from precise density measurements in solvent mixtures of propylene carbonate (PC) with dimethylformamide (DMF), tetrahydrofuran (THF), acetonitrile (AN), and methyl formate (MF). The scaled particle theory is used to calculate the contributions of the cavity formation and the electrolyte-solvent interactions to the standard partial-molar volumes. It is shown that V20, ϕ is strongly dependent on the nature of the solvents, and the trends in V20, ϕ with composition of the solvent mixtures are determined by the interaction volumes of electrolytes with solvents. The results are discussed in terms of ionic preferential solvation, packing effect of solvents in the solvation shell, and electrostriction of solvents by ion.Key words: partial-molar volume, scaled particle theory, lithium salts, propylene carbonate, solvent mixtures, lithium battery electrolytes.
Enzymatic oxidation of cyclopropylbenzene: structures of new metabolites and possible mechanistic implications
Authors: Bui Vu P , Nguyen Minh , Hansen Jeff , Baker John , Hudlicky Tomas
Published: July 2002

Cyclopropylbenzene was subjected to whole-cell fermentation with either Escherichia coli JM109 (pDTG601) or E. coli JM109 (pDTG602), expressing toluene dioxygenase and toluene dioxygenase  dihydrodiol dehydrogenase enzymes, respectively. The corresponding metabolites, 3-cyclopropylcyclohexa-3,5-diene-1,2-diol (3) and 3-cyclopropylbenzene-1,2-diol (5) have been isolated in yields of 2.5 and 1 g L1, respectively. The absolute stereochemistry correlation for 3 is provided, along with a preliminary discussion of its potential in asymmetric synthesis. Possible mechanistic implications are indicated for the enzymatic oxygenation through the use of calculations. Experimental data are provided for all new compounds.Key words: cyclopropylbenzene, bio-oxidation, cis-diene diol, catechol, JM109 (pDTG601), JM109 (pDTG602), dioxygenase.
Fixed stereochemical control in the synthesis of new mono- and disubstituted 2-phenyl-6-aza-1,3-dioxa-2-borabenzocyclononenes
Authors: Beltrán Hiram I , Alas S Jesús , Santillan Rosa , Farfán Norberto
Published: July 2002

Five new boronates of the type 2-phenyl-6-aza-1,3-dioxa-2-borabenzocyclononenes (6ae) were prepared from substituted 2-[(2-hydroxyethylamino)methyl]phenols (4ae) and phenylboronic acid (5) in benzene-EtOH (4:1) mixtures. Tridentate ligands 4ae and boronates 6ae were characterized by 1H, 13C, 15N, and 2D-NMR (HETCOR, NOESY, and COLOC) experiments, FT-IR, mass spectra, and elemental analysis, as well as 11B NMR for the boron derivatives. Suitable monocrystals of 2-[(2-hydroxyethylamino)methyl]phenol hydrochloride (4a), cis-2-phenyl-6-aza-1,3-dioxa-2-borabenzocyclononene (6a), (2S,5R,6S)-2,5-diphenyl-6-aza-1,3-dioxa-2-borabenzocyclononene (6b), and (2S,4R,5R,6S)-2,4-diphenyl-5-methyl-6-aza-1,3-dioxa-2-borabenzocyclononene (6e) were obtained and their structures are discussed. The X-ray structures of 6a, 6b, and 6e, as well as the NMR data established that the configurations at the nitrogen and boron atoms are both "S" and the transannular fusion is cis. A semi-empirical (SAM1) study was used to calculate the energy for all possible stereoisomers, showing that the stabilization increases as the THC (tetrahedral character of the boron atom) increases and also as the N[Formula: see text]B bond distance decreases, in agreement with the experimental results and previous work related to amino acid boronates.Key words: boron compounds, X-ray structures, NMR, boronates, synthesis.
Growth increments and stability over time in fast-growing forest tree species
Authors: Zamudio F , Wolfinger R D
Published: July 2002

We review an analytical procedure useful for measuring the influence of time on the phenotypic expression of cumulative growth. It consists of separating the genetic control into two meaningful components: the cumulative genetic effect of growth increments and the effect of genotype × time interaction. The analysis is performed via a hierarchical mixed linear model. Data from three Pinus tecunumanii Eguiluz & J.P. Perry provenanceprogeny trials established by the CAMCORE Cooperative in South America were used to assess the practical application of the method. Results suggest that the simple observation of ageage correlations for cumulative growth can be misleading, because they hide the effects of family and within-family variation. The partition of cumulative growth into mutually exclusive growth increments can help to discriminate covariance components, which are also useful to predict the degree of association between growth at different ages and the potential value for early selection.
Characterization of cyclic AMP-regulated chloride conductance in the pigmented rabbit conjunctival epithelial cells
Authors: Shiue Michael H.I , Gukasyan Hovhannes J , Kim Kwang-Jin , Loo Donald D.F , Lee Vincent H.L
Published: July 2002

We have previously reported that the pigmented rabbit conjunctiva is a Clsecreting tissue, subject to cAMP, Ca2+, and PKC modulation. The present study was conducted to characterize, at the cellular and molecular levels, cAMP-regulated Clchannels in rabbit conjunctival epithelial cells. cAMP-inducible Clchannel properties were evaluated by monitoring the whole-cell currents using patch clamp techniques. Results showed that 10 μM forskolin significantly stimulated a glibenclamide-inhibitable whole-cell conductance by approximately five-fold. Furthermore, reduction of the Clconcentration in the bathing solution through partial substitution of NaCl with Na-isethionate resulted in a rightward shift of the reversal potential for both baseline and forskolin-stimulated whole-cell currents from 0 to values close to the theoretical Clreversal potential predicted by the Nernst equation. Western blot analysis with a monoclonal antibody recognizing the epitope in the C-terminus of the cystic fibrosis transmembrane conductance regulator (CFTR) showed a positive band at its molecular weight, approximately 170 kD. Immunostaining under confocal microscopy revealed a CFTR specific signal in the apical sections of primary conjunctival epithelial cells. In addition, RT-PCR detection amplified a cDNA fragment 100% identical to the predicted portion of the cloned rabbit CFTR message. The stage is thus set for determining the extent of CFTR contribution to cAMP-regulated Clconductance in pigmented rabbit conjunctival epithelial cells.Key words: conjunctiva, chloride current, CFTR, chloride channel, patch clamp, cyclic AMP, whole-cell.
Trophic effects of rainfall onClethrionomys rutilusvoles: an experimental test in a xeric boreal forest in the Yukon Territory
Authors: Carrier Patrick , Krebs Charles J
Published: July 2002

The Kluane forest is unusual in that it is less productive than other boreal forests because it lies in a rain-shadow zone. Densities of the boreal red-backed vole Clethrionomys rutilus are known to be food-limited in the Kluane region, and its food sources (mostly plants) could be rainfall-limited. We therefore tested the hypothesis that rainfall indirectly controlled vole densities in the Kluane region. Our predictions were that (i) food for voles would increase with additional rainfall and (ii) food-limited voles would in turn increase in numbers. Three sites in the Kluane forest were irrigated during the growing season for 5 years, and these were compared with three paired control sites without irrigation. Irrigation increased rainfall 91% above normal, on average. Neither understory plants, trees, invertebrates, nor the vole population reacted to irrigation. Only mushroom biomass increased. Hence, the above hypothesis must be rejected. The vegetation is not directly water-limited at these sites, and nitrogen limitation probably prevailed. However, mushroom biomass increased with irrigation and in turn should have increased nitrogen mineralization. It is therefore unclear why plant production and vole numbers did not increase with mushroom biomass on the irrigated sites.
Quantifying barrier effects of roads and seismic lines on movements of female woodland caribou in northeastern Alberta
Authors: Dyer Simon J , O'Neill Jack P , Wasel Shawn M , Boutin Stan
Published: July 2002

Linear developments such as roads, seismic lines, and pipeline rights-of-way are common anthropogenic features in the boreal forest of Alberta. These features may act as barriers to the movement of threatened woodland caribou (Rangifer tarandus caribou). Thirty-six woodland caribou were captured and fitted with global positioning system collars. These collared caribou yielded 43 415 locations during the 12-month study period. We compared rates of crossing roads and seismic lines with rates at which caribou crossed simulated roads and seismic lines created using ArcInfo GIS. Seismic lines were not barriers to caribou movements, whereas roads with moderate vehicle traffic acted as semipermeable barriers to caribou movements. The greatest barrier effects were evident during late winter, when caribou crossed actual roads 6 times less frequently than simulated road networks. Semipermeable barrier effects may exacerbate functional habitat loss demonstrated through avoidance behaviour. This novel approach represents an important development in the burgeoning field of road ecology and has great potential for use in validating animal-movement models.
Reaction norms and production costs of predator-induced morphological defences in a larval dragonfly (Leucorrhinia dubia: Odonata)
Authors: Johansson Frank
Published: July 2002

To understand the evolution and ecology of inducible defence we need to understand the genetics and costs underlying this phenomenon. It has been suggested that the abdominal spines of odonate larvae work as a defensive trait, and that the presence of fish predators induces the production of longer abdominal spines. This study was designed to answer the following questions: (i) What is the shape of the reaction norms of spine length in the larvae of the dragonfly Leucorrhinia dubia reared in the presence and absence of fish? (ii) Does the production of longer spines imply that production costs are incurred in terms of development time or size? I performed a laboratory experiment in which I raised 30 families of L. dubia larvae in the presence and absence of fish. In general, the presence of fish induced the production of longer abdominal spines in the larvae, and there was a genotype × environment interaction, suggesting the potential for evolution of plasticity of the traits. No production costs could be found with respect to development time and size at final instar.
APPLICATIONS OF QUANTUM DOTS IN SEMICONDUCTOR LASERS
Authors: Ledentsov Nikolai N. , Ustinov Victor M. , Bimberg Dieter , Lott James A. , Alferov Zh. I.
Published: July 2002

Quantum Dots (QD) provide unique opportunities to extend all the basic properties of heterostructure lasers and move further their applications. Practical fabrication of QD lasers became possible when techniques for self-organized growth allowed fabrication of dense and uniform arrays of narrow-gap nanodomains, coherently inserted in a semiconductor crystal matrix. Using of InAs QD lasers enabled significant improvement of device performance and extension of the spectral range on GaAs substrates to mainstream telecom wavelengths. Continuous wave 1.3 μm room-temperature output power of ~300 mW single mode for edge-emitters and of 1.2 mW multimode for vertical-cavity surface-emitting lasers are realized. Long operation lifetimes are manifested. The breakthrough become possible both due to development of self-organized growth and defect-reduction techniques in QD technology.
LOCAL HYDROGEN AND DEUTERIUM VIBRATIONAL MODES IN Si-DOPED GaAs
Authors: ROY S. D. D. , MURUGAN P. , RAMACHANDRAN K. , KRISHNAMURTHY N.
Published: July 2002

Infrared absorption on GaAs doped with the isotopes of silicon under hydrogen or deuterium plasma treatment has shown the presence of two new localized modes, all in the range of 625–1725 cm-1. We present a simple nine-atom molecular model to compute these defect modes by assuming the hydrogen or deuterium to be bound in the antibonding position of the substituted Si atom, resulting in a defect complex of C3V symmetry. The two new vibrational modes of the paired Si are found with a small isotope shift, when H is replaced by D. Group theoretical methods are employed for the precise identification of the localized modes.
COMPUTING STEADY STATE FLOWS WITH AN ACCELERATED LATTICE BOLTZMANN TECHNIQUE
Authors: BERNASCHI MASSIMO , SUCCI SAURO , CHEN HUDONG , ZHANG RAOYANG
Published: July 2002

An accelerated version of the lattice Boltzmann equation aimed at fast attainment of steady-state flow conditions is presented. Significant computational savings as compared to the standard explicit LBE scheme are obtained for cavity flows in two dimensions.
THE ENERGY OF THE GAMMA METRIC IN THE MØLLER PRESCRIPTION
Authors: YANG I-CHING , RADINSCHI IRINA
Published: July 2002

We obtain the energy distribution of the gamma metric using the energy–momentum complex of Møller. The result is the same as that obtained by Virbhadra in the Weinberg prescription.
MAGNETIC ZN SYMMETRY IN 2+1 DIMENSIONS
Authors: KOVNER A.
Published: July 2002

This review describes the role of magnetic symmetry in (2+1)-dimensional gauge theories. In confining theories without matter fields in fundamental representation the magnetic symmetry is spontaneously broken. Under some mild assumptions, the low-energy dynamics is determined universally by this spontaneous breaking phenomenon. The degrees of freedom in the effective theory are magnetic vortices. Their role in confining dynamics is similar to that played by pions and σ in the chiral symmetry breaking dynamics. I give an explicit derivation of the effective theory in (2+1)-dimensional weakly coupled confining models and argue that it remains qualitatively the same in strongly coupled (2+1)-dimensional gluodynamics. Confinement in this effective theory is a very simple classical statement about the long range interaction between topological solitons, which follows (as a result of a simple direct classical calculation) from the structure of the effective Lagrangian. I show that if fundamentally charged dynamical fields are present the magnetic symmetry becomes local rather than global. The modifications to the effective low energy description in the case of heavy dynamical fundamental matter are discussed. This effective Lagrangian naturally yields a bag like description of baryonic excitations. I also discuss the fate of the magnetic symmetry in gauge theories with the Chern–Simons term.
ABOUT THE SIMULTANEOUS CO-EXISTENCE OF INSTANTANEOUS AND RETARDED INTERACTIONS IN CLASSICAL ELECTRODYNAMICS
Authors: ŠKOVRLJ LjUBA , IVEZIĆ TOMISLAV
Published: July 2002

In this paper it is proved that, contrary to the results found by A.E. Chubykalo and S.J. Vlaev (Int. J. Mod. Phys.14, 3789 (1999)), the retarded electric and magnetic fields for a uniformly accelerated charge exactly satisfy Maxwell equations (ME). Furthermore, it is shown that ME are correctly written in the usual form with the partial derivatives and thus not, as proposed by Chubykalo and Vlaev, with the total derivatives.
THE TRAPPED ANOMALOUS COMPONENT OF THE COSMIC RAYS: THE SHORT OVERVIEW OF EXPERIMENTS
Authors: PANASYUK M. I.
Published: July 2002

The experimental data on the chemical composition of galactic cosmic rays (GCR) are analysed in the energy range between ≈ 10 MeV/nucl and ≈ PeV. The lower part of the energy range corresponds to the so-called anomalous cosmic rays (ACR). These particles with low charge values can easily penetrate through the Earth's magnetic field and after charge-exchange with neutrals of the Earth's atmosphere increase their charge states to full stripping. As a result of satellite experiments it was shown, that these secondary particles can become trapped in the geomagnetic field and form a radiation belt. Below a short survery of the experimental results which led to this discovery is given.
SIMULATION OF PARTICLE FLUXES IN THE EARTH'S VICINITY
Authors: PLYASKIN VASSILI
Published: July 2002

The results of calculations of the fluxes of charged particles and atmospheric neutrinos are discussed. Results on charged particles are compared with the AMS measurements.
MASSIVE NEUTRINOS AND THEORETICAL DEVELOPMENTS
Authors: STRUMIA ALESSANDRO , VISSANI FRANCESCO
Published: July 2002

This presentation includes recent developments on massive neutrinos and introductory material. Most discussion stays close to the data (=phenomenology), but it is integrated with some more formal (=theoretical) remarks. The importance of oscillations for supernova neutrinos is emphasized, and the peculiar role of νe events in this connection is discussed. A new bound on neutrino mass scale, based on double beta decay bound, is obtained.
SEARCHES FOR DARK MATTER PARTICLES THROUGH COSMIC RAY MEASUREMENTS
Authors: ULLIO PIERO
Published: July 2002

We consider the hypothesis that dark matter is made of weakly interacting massive particles (WIMPs) and describe how their pair annihilation in the galactic halo generates exotic cosmic ray fluxes. Features for generic WIMP models are reviewed, pointing out cases in which clear signatures arise. Implications from available and upcoming measurements are discussed.
THE AGILE MISSION AND GAMMA-RAY ASTROPHYSICS
Authors: TAVANI MARCO
Published: July 2002

Gamma-ray astrophysics in the energy range between 30 MeV and 30 GeV is in desperate need of arcminute angular resolution and source monitoring capability. The AGILE Mission planned to be operational in 2004-2006 will be the only space mission entirely dedicated to gamma-ray astrophysics above 30 MeV. The main characteristics of AGILE are the simultaneous X-ray and gamma-ray imaging capability (reaching arcminute resolution) and excellent gamma-ray timing (10-100 microseconds). AGILE scientific program will emphasize a quick response to gamma-ray transients and multiwavelength studies of gamma-ray sources.
Multilayer Extension of Two-Dimensional Solvable Statistical Models to Three Dimensions
Authors: Popkov V.
Published: July 2002

We review the method of constructing solvable models in three dimensions, by starting from two-dimensional solvable models. The solvable three-dimensional models thus constructed do possess positive Boltzmann weights. These are multilayer two-dimensional systems with interactions in the third direction which can be interpreted as nearest-neighbour interactions. The set of conditions corresponding to the general 3D multilayer extension of solvable 2D models is derived.
Boundary-Dependent Local Behavior for 2-D Dimer Models
Authors: Propp James
Published: July 2002

The shape of the boundary of a finite-region of a grid has a strong effect on the local entropy and local statistics (frequencies of local patterns) of a random dimer configuration. For large regions these quantities appear to be locally constant almost everywhere, but for many regions the local statistics are subject to macroscopic variation. The local frequencies associated with individual bonds can be determined in closed form for important special cases, and their large-scale non-constancy is probably related to the existence of a two-parameter family of extremal Gibbs measures for the models in question.
A Higher-Level Bailey Lemma
Authors: Schilling Anne , Warnaar S. Ole
Published: July 2002

We propose a generalization of Bailey's lemma, useful for proving q-series identities. As an application, generalizations of Euler's identity, the Rogers–Ramanujan identities, and the Andrews–Gordon identities are derived. This generalized Bailey lemma also allows one to derive the branching functions of higher-level [Formula: see text] cosets.
Joint Evolution of Two Domany–Kinzel Cellular Automata
Authors: Gueuvoghlanian Emílio P. , Tomé Tânia
Published: July 2002

We analyze the joint dynamics of two systems each one evolving in time according to the Domany–Kinzel rules. Two prescriptions for the joint evolution are studied. We make analytical approaches, based on dynamical mean-field approximations at the level of three-site correlations, to obtain the phase diagram. Also, the susceptibilities associated with the order parameters are calculated by using a pair approximation.
Theory of Magnetic Short-Range Order for Itinerant Electron Systems
Authors: Trapper U. , Ihle D. , Fehske H.
Published: July 2002

On the basis of the one-band t–t′-Hubbard model a self-consistent renormalization theory of magnetic short-range order (SRO) in the paramagnetic phase is presented combining the four-field slave-boson functional-integral scheme with the cluster variational method. Contrary to previous SRO approaches the SRO is incorporated at the saddle-point and pair-approximation levels. A detailed numerical evaluation of the theory is performed at zero temperature, where both the hole- and electron-doped cases as well as band-structure effects are studied. The ground-state phase diagram shows the suppression of magnetic long-range order in favour of a paramagnetic phase with antiferromagnetic SRO in a wide doping region. In this phase the uniform static spin susceptibility increases upon doping up to the transition to the Pauli paraphase. Comparing the theory with experiments on high-T c cuprates a good agreement is found.
A Quantum Field Theoretical Analysis of Spin-Half Metamagnetism
Authors: Tuszyński J. A. , Dixon J. M.
Published: July 2002

A number of metallic compounds such as FeRh, Mn3GaC , and FeCl2 exhibit the interesting property of metamagnetism, i.e. the presence of order–order magnetic-phase transitions. The microscopic Hamiltonian that is commonly used to describe this class of system is of Heisenberg type with competing exchange interactions between the nearest- and next-nearest neighbours. Starting from this quantum Hamiltonian, through several transformations, it is possible to obtain an effective second-quantized Hamiltonian which has a two-body interaction term. A recent method of analyzing such Hamiltonians is then applied based on exact calculations for the corresponding nonlinear equation of motion. This is followed by quantization about the classical solutions. Stability conditions imposed on the classical solutions agree with earlier results.
Surface Waves and Forced Oscillations in QHE Planar Samples
Authors: Cabo Alejandro , Correa Alejandro , Guevara Ramón , Rodriguez Carlos
Published: July 2002

Dispersion relations and polarizations for surface waves in infinite planar samples in the QHE regime are explicitly determined in the small wavevector limit in which the dielectric tensor can be considered local. The wavelength and frequency regions of applicability of the results extends to the infrared region for typical experimental conditions. Then, standard samples with millimetric sizes seem to be able to support such excitations. Forced oscillations are also determined which should be generated in the 2DEG by external electromagnetic sources. They show an almost frequency independent wavelength which decreases with the magnetic field. A qualitative model based in these solutions is also presented to describe a recently found new class of resonances appearing near the edge of a 2DEG in the QHE regime.
Microscopic Imaging of Josephson Junction Dynamics
Authors: Doderer Thomas
Published: July 2002

Josephson junctions show various dynamical regimes including cavity waves and nonlinear solitonic excitations. The use of spatially resolved measurements is important to further our knowledge about the junction dynamics. We present experimental results obtained by low-temperature scanning electron microscopy offering a spatial resolution of about 1 μm. This technique offers the possibility to probe the dynamics in the time average by applying a weak and localized thermal perturbation. With the appropriate electron beam power this perturbation does not destroy the dynamical state of the junction. A theoretical approach relating the obtained images to real junction dynamics is presented. We show examples of our imaging results dealing with cavity modes, single-, and multi-soliton dynamics in Josephson tunnel junctions made from Nb and Pb-alloy superconductors as well as cavity modes in grain boundary Josephson junctions made from the high-critical-temperature superconductor YBa2Cu3O 7-δ. With high-quality Nb and Pb-alloy junctions we are able to confirm existing theoretical models about cavity resonances and soliton dynamics. Furthermore, we prove the existence of soliton-type motion along the diagonals of square junctions predicted theoretically, discover several stable multi-soliton modes, and directly show the Lorentz contraction of solitons.
Determination of the Ground State Geometries of Copper Clusters by Simulated Annealing
Authors: Banerjea Amitava , Datta Radhika Prosad , Mookerjee Abhijit , Bhattacharyya A. K.
Published: July 2002

We determine the lowest energy structures of small (10–20 atoms) copper clusters. The semi-empirical Equivalent Crystal Theory (ECT) is used in conjunction with the Metropolis Monte Carlo algorithm to determine the equilibrium geometry of each cluster via simulated annealing. The optimum structures of the clusters in this size range are found to be derived from icosahedral structures. The 13-atom cluster is an icosahedron and the 19-atom one a double-icosahedron. The other sizes show structures related to these. The 10- and 11-atom clusters, however, show somewhat different structures. We report the variation of binding energy, as obtained from ECT, with cluster size.