bluuebunny/crossref_metadata_2025_split huggingface dataset:
A review of methods to calculate extreme wind speeds
Authors: Palutikof J P , Brabson B B , Lister D H , Adcock S T 
Published: July 2002

AbstractMethods to calculate extreme wind speeds are described and reviewed, including ‘classical’ methods based on the generalized extreme value (GEV) distribution and the generalized Pareto distribution (GPD), and approaches designed specifically to deal with short data sets. The emphasis is very much on the needs of users who seek an accurate method to derive extreme wind speeds but are not fully conversant with up‐to‐date developments in this complex subject area. First, ‘standard’ methods are reviewed: annual maxima, independent storms, r‐largest extremes with the GEV distribution, and peak‐over‐threshold extremes with the GPD. Techniques for calculating the distribution parameters and quantiles are described. There follows a discussion of the factors which must be considered in order to fulfil the criterion that the data should be independent and identically distributed, and in order to minimize standard errors. It is commonplace in studies of extreme wind speeds that the time series available for analysis are very short. Finally, therefore, the paper deals with techniques applicable to data sets as short as two years, including simulation modelling and methods based on the parameters of the parent distribution. Copyright © 1999 Royal Meteorological Society
Crucial importance of pack size in the African wild dog Lycaon pictus
Authors: Courchamp Franck , Macdonald David W. 
Published: July 2002

AbstractAlthough the massive organized slaughter of African wild dogs, Lycaon pictus, largely ended several decades ago, this endangered canid continues to decline and faces extinction. Several lines of evidence suggest that this arises from obligate cooperative breeding, which makes Lycaon more sensitive to anthropogenic mortality. A number of behaviours in this species are characterized by a reliance on helpers. These include cooperative hunting, defence from kleptoparasitism, pup feeding and baby‐sitting. As a result, there are strong, positive relationships between pack size and the production and survival of pups, and pairs of wild dogs are often unsuccessful at raising offspring without the assistance of helpers. Consequently, a pack in which membership drops below a critical size may be caught in a positive feedback loop: poor reproduction and low survival further reduce pack size, culminating in failure of the whole pack. Here, we review the literature to reveal the importance of pack size in the African wild dog. Most importantly, we argue that there is a critical minimum threshold, below which packs face an increasing probability of extinction ‐ an Allee effect with consequences for the conservation of this species, and of other obligate cooperators.
Eleven Densely Clustered Genes, Six of them Novel, in 176 kb of Mouse t-complex DNA
Authors: Kargul George J. , Nagaraja Ramaiah , Shimada Tokihiko , Grahovac Marija J. , Lim Meng K. , Nakashima Hiroshi , Waeltz Paul , Ma Peter , Chen Ellson , Schlessinger David , Ko Minoru S.H. 
Published: July 2002

Targeted sequencing of the mouse t-complex has started with a 176-kb, gene-rich BAC localized with six PCR-based markers in inversion 2/3 of the highly duplicated region. The sequence contains 11 genes recovered primarily as cDNAs from early embryonic collections, including Igfals (previously placed on chromosome 17),Nubp2 (a fully characterized gene), Jsap1 (a JNK-binding protein), Rsp29 (the mouse homologue of the rat gene), Ndk3 (a nucleoside diphosphate kinase), and six additional putative genes of unknown function. With 50% GC content, 75% of the DNA transcribed, and one gene/16.0 kb (on average), the region may qualify as one of the most gene-dense segments in the mouse genome and provides candidates for dosage-sensitive phenotypes and mouse embryonic lethals mapped to the vicinity.[The sequence data described in this paper have been submitted to the GenBank data library under accession no. AF220294.]
Turgor Regulation in Osmotically Stressed Arabidopsis Epidermal Root Cells. Direct Support for the Role of Inorganic Ion Uptake as Revealed by Concurrent Flux and Cell Turgor Measurements
Authors: Shabala Sergey N. , Lew Roger R. 
Published: July 2002

Abstract
Hyperosmotic stress is known to significantly enhance net uptake of inorganic ions into plant cells. Direct evidence for cell turgor recovery via such a mechanism, however, is still lacking. In the present study, we performed concurrent measurements of net ion fluxes (with the noninvasive microelectrode ion flux estimation technique) and cell turgor changes (with the pressure-probe technique) to provide direct evidence that inorganic ion uptake regulates turgor in osmotically stressed Arabidopsis epidermal root cells. Immediately after onset of hyperosmotic stress (100/100 mmmannitol/sorbitol treatment), the cell turgor dropped from 0.65 to about 0.25 MPa. Turgor recovery started within 2 to 10 min after the treatment and was accompanied by a significant (30–80 nmol m−2 s−1) increase in uptake of K+, Cl−, and Na+ by root cells. In most cells, almost complete (&gt;90% of initial values) recovery of the cell turgor was observed within 40 to 50 min after stress onset. In another set of experiments, we combined the voltage-clamp and the microelectrode ion flux estimation techniques to show that this process is, in part, mediated by voltage-gated K+ transporters at the cell plasma membrane. The possible physiological significance of these findings is discussed.
Apoplastic Sugars, Fructans, Fructan Exohydrolase, and Invertase in Winter Oat: Responses to Second-Phase Cold Hardening
Authors: Livingston David P. , Henson Cynthia A. 
Published: July 2002

Abstract
Changes in apoplastic carbohydrate concentrations and activities of carbohydrate-degrading enzymes were determined in crown tissues of oat (Avena sativa L., cv Wintok) during cold hardening. During second-phase hardening (−3°C for 3 d) levels of fructan, sucrose, glucose, and fructose in the apoplast increased significantly above that in nonhardened and first-phase-hardened plants. The extent of the increase in apoplastic fructan during second-phase hardening varied with the degree of fructan polymerization (DP) (e.g. DP3 and DP4 increased to a greater extent than DP7 and DP &gt; 7). Activities of invertase and fructan exohydrolase in the crown apoplast increased approximately 4-fold over nonhardened and first-phase-hardened plants. Apoplastic fluid extracted from nonhardened, first-phase-hardened, and second-phase-hardened crown tissues had low levels, of symplastic contamination, as determined by malate dehydrogenase activity. The significance of these results in relation to increases in freezing tolerance from second-phase hardening is discussed.
Genetic Interactions between Phytochrome A, Phytochrome B, and Cryptochrome 1 during Arabidopsis Development1
Authors: Neff Michael M. , Chory Joanne 
Published: July 2002

Abstract
Single, double, and triple null combinations of Arabidopsis mutants lacking the photoreceptors phytochrome (phy) A (phyA-201), phyB (phyB-5), and cryptochrome (cry) 1 (hy4-2.23n) were examined for de-etiolation responses in high-fluence red, far-red, blue, and broad-spectrum white light. Cotyledon unhooking, unfolding, and expansion, hypocotyl growth, and the accumulation of chlorophylls and anthocyanin in 5-d-old seedlings were measured under each light condition and in the dark. phyA was the major photoreceptor/effector for most far-red-light responses, although phyB and cry1 modulated anthocyanin accumulation in a phyA-dependent manner. phyB was the major photoreceptor in red light, although cry1 acted as a phyA/phyB-dependent modulator of chlorophyll accumulation under these conditions. All three photoreceptors contributed to most blue light deetiolation responses, either redundantly or additively; however, phyB acted as a modulator of cotyledon expansion dependent on the presence of cry1. As reported previously, flowering time in long days was promoted by phyA and inhibited by phyB, with each suppressing the other's effect. In addition to the effector/modulator relationships described above, measurements of hypocotyls from blue-light-grown seedlings demonstrated phytochrome activity in blue light and cry1 activity in a phyAphyB mutant background.
Barley Coleoptile Peroxidases. Purification, Molecular Cloning, and Induction by Pathogens1
Authors: Kristensen Brian Kåre , Bloch Helle , Rasmussen Søren Kjærsgaard 
Published: July 2002

Abstract
A cDNA clone encoding the Prx7 peroxidase from barley (Hordeum vulgare L.) predicted a 341-amino acid protein with a molecular weight of 36,515. N- and C-terminal putative signal peptides were present, suggesting a vacuolar location of the peroxidase. Immunoblotting and reverse-transcriptase polymerase chain reaction showed that the Prx7 protein and mRNA accumulated abundantly in barley coleoptiles and in leaf epidermis inoculated with powdery mildew fungus (Blumeria graminis). Two isoperoxidases with isoelectric points of 9.3 and 7.3 (P9.3 and P7.3, respectively) were purified to homogeneity from barley coleoptiles. P9.3 and P7.3 had Reinheitszahl values of 3.31 and 2.85 and specific activities (with 2,2′-azino-di-[3-ethyl-benzothiazoline-6-sulfonic acid], pH 5.5, as the substrate) of 11 and 79 units/mg, respectively. N-terminal amino acid sequencing and matrix-assisted laser desorption/ionization time-of-flight mass-spectrometry peptide analysis identified the P9.3 peroxidase activity as due to Prx7. Tissue and subcellular accumulation of Prx7 was studied using activity-stained isoelectric focusing gels and immunoblotting. The peroxidase activity due to Prx7 accumulated in barley leaves 24 h after inoculation with powdery mildew spores or by wounding of epidermal cells. Prx7 accumulated predominantly in the epidermis, apparently in the vacuole, and appeared to be the only pathogen-induced vacuolar peroxidase expressed in barley tissues. The data presented here suggest that Prx7 is responsible for the biosynthesis of antifungal compounds known as hordatines, which accumulate abundantly in barley coleoptiles.
Senescence-Associated Gene Expression during Ozone-Induced Leaf Senescence in Arabidopsis1
Authors: Miller Jennifer D. , Arteca Richard N. , Pell Eva J. 
Published: July 2002

Abstract
The expression patterns of senescence-related genes were determined during ozone (O3) exposure in Arabidopsis. Rosettes were treated with 0.15 μL L−1 O3 for 6 h d−1 for 14 d. O3-treated leaves began to yellow after 10 d of exposure, whereas yellowing was not apparent in control leaves until d 14. Transcript levels for eight of 12 senescence related genes characterized showed induction by O3. SAG13(senescence-associated gene), SAG21, ERD1(early responsive to dehydration), and BCB (blue copper-binding protein) were induced within 2 to 4 d of O3 treatment; SAG18, SAG20, and ACS6 (ACC synthase) were induced within 4 to 6 d; and CCH (copper chaperone) was induced within 6 to 8 d. In contrast, levels of photosynthetic gene transcripts,rbcS (small subunit of Rubisco) and cab(chlorophyll a/b-binding protein), declined after 6 d. Other markers of natural senescence, SAG12,SAG19, MT1 (metallothionein), andAtgsr2 (glutamine synthetase), did not show enhanced transcript accumulation. When SAG12promoter-GUS (β-glucuronidase) andSAG13 promoter-GUS transgenic plants were treated with O3, GUS activity was induced in SAG13-GUS plants after 2 d but was not detected in SAG12-GUS plants.SAG13 promoter-driven GUS activity was located throughout O3-treated leaves, whereas control leaves generally showed activity along the margins. The acceleration of leaf senescence induced by O3 is a regulated event involving many genes associated with natural senescence.
Sodalite, Na4Si3Al3O12Cl: structure and ionic mobility at high temperatures by neutron diffraction
Authors: McMullan R. K. , Ghose S. , Haga N. , Schomaker V. 
Published: July 2002

Crystal data: Na4Si3Al3O12Cl, cubic, space group P43n, Z = 2, F(000) = 233.06 fm, μ

n
= 0.06 cm−1, lattice parameter ao
(Å) [T] (K) at eight temperatures: 8.882 (1) [295]; 8.902 (2) [500]; 8.912 (1) [600]; 8.923 (1) [700] 8.951 (2) [800]; 8.971(1) [900]; 8.988 (1) [1000]; 9.037 (1) [1200]. The crystal structure has been determined at six temperatures (295 ≤ T ≤ 1200 K) based on neutron diffraction data with (sin θ/λ) < 0.80 Å−1. Besides conventional parameters, the least-squares refinement model included thermal tensor parameters up to fourth-order for sodium and chlorine (295 ≤ T ≤ 1200 K) and up to third-order for oxygen (T ≥ 700 K), together with the 1:1 coupled site occupancy factors of sodium and chlorine (T = 1200 K). The indices-of-fit, wR(F
2), are in the range 0.015–0.028 with observation-to-parameter ratios from 7.0 to 8.6. Bond lengths and angles in the aluminosilicate framework have average e.s.d.'s less than 0.002 Å and 0.08°. Between 295 and 1200 K, the observed Si—O (Al—O) bond lengths differ by −0.015 Å (−0.012 Å); corrections for librating rigid SiO4 (AlO4) groups change the difference to +0.004 Å (+0.006 Å), compared with the 295 K value of 1.620 Å (1.741 Å). The unique Si—O—Al angle increases from 138.24° (295 K) to 146.87° (1200 K), while the Si and Al valence angles are virtually unchanged. Between 295 and 1200 K the [Na4Cl] clusters expand with increases in the Na—Cl bond lengths of 0.200 Å, with simultaneous increases in Na—O bond lengths of 0.145 Å and decreases in the shortest Na...O contact distances of 0.126 Å. The thermal expansion of sodalite is attributed to the increasing amplitudes of coupled translational motion of the Na+ ions and the librational motion of the [Al/ SiO4] tetrahedra, leading to the untwisting of the aluminosilicate framework. Maps of the probability density functions for Na+ and Cl− indicate ionic diffusion paths along (111) directions. There is a finite probability of finding the Na+ ion within the plane of the next-nearest O atoms, suggesting that Na+ jumps from an occupied to an unoccupied site in the next-nearest cage through the six-membered ring of [Al/SiO4] tetrahedra.
Bulk modulus and high-pressure crystal structures of tetrakis(trimethylsilyl)methane C[Si(CH3)3]4 determined by X-ray powder diffraction
Authors: Dinnebier Robert E. , Carlson Stefan , van Smaalen Sander 
Published: July 2002

The pressure dependence of the crystal structure of cubic tetrakis(trimethylsilyl)methane C[Si(CH3)3]4 (TC) (P < 16.0 GPa, T = 298 K) is reported using high-resolution angle-dispersive X-ray powder diffraction. The compound has crystal structures with the molecules in a cubic-close-packed (c.c.p.) arrangement. It shows three phase transitions in the measured pressure range. At ambient conditions, TC has space group Fm{\bar 3}m (Z = 4) with a = 12.8902 (2) Å, V = 2141.8 (1) Å3 (phase I). Between 0 and 0.13 GPa TC exhibits a first-order phase transition into a structure with space group Pa{\bar 3} (phase II). A second first-order phase transition occurs between 0.2 and 0.28 GPa into a structure with space group P213 (phase III). Under non-hydrostatic pressure conditions (P > 10  GPa) a transformation is observed into a c.c.p. structure that is different from the face-centred-cubic structure at ambient conditions. A non-linear compression behaviour is observed, which could be described by a Vinet relation in the range 0.28–4.8 GPa. The extrapolated bulk modulus of the high-pressure phase III was determined to be K
0 = 7.1 (8) GPa. The crystal structures in phase III are refined against X-ray powder data measured at several pressures between 0.49 and 4.8 GPa, and the molecules are found to be fully ordered. This is interpreted to result from steric interactions between neighbouring molecules, as shown by analysing the pressure dependence of intramolecular angles, torsion angles and intermolecular distances. Except for their cell dimensions, phases I, II and III are found to be isostructural to the corresponding phases at low temperatures.
Structures and phase transitions of the A
7PSe6 (A = Ag, Cu) argyrodite-type ionic conductors. II. β- and γ-Cu7PSe6
Authors: Gaudin E. , Boucher F. , Petricek V. , Taulelle F. , Evain M. 
Published: July 2002

The crystal structures of two of the three polymorphic forms of the Cu7PSe6 argyrodite compound are determined by means of single-crystal X-ray diffraction. In the high-temperature form, at 353 K, i.e. 33 K above the first phase transition, γ-Cu7PSe6 crystallizes in cubic symmetry, space group F4¯3m. The full-matrix least-squares refinement of the structure leads to the residual factors R = 0.0201 and wR = 0.0245 for 31 parameters and 300 observed independent reflections. In the intermediate form, at room temperature, β-Cu7PSe6 crystallizes again in cubic symmetry, but with space group P213. Taking into account a merohedric twinning, the refinement of the β-Cu7PSe6 structure leads to the residual factors R = 0.0297 and wR = 0.0317 for 70 parameters and 874 observed, independent reflections. The combination of a Gram–Charlier development of the Debye–Waller factor and a split model for copper cations reveals the possible diffusion paths of the d
10 species in the γ-Cu7PSe6 ionic conducting phase. The partial ordering of the Cu+
d
10element at the phase transition is found in concordance with the highest probability density sites of the high-temperature phase diffusion paths. A comparison between the two Cu7PSe6 and Ag7PSe6 analogues is carried out, stressing the different mobility of Cu+ and Ag+ and their relative stability in low-coordination chalcogenide environments.
Structure of a Monoclinic Crystal Form of Cytochrome b1 (Bacterioferritin) from E. coli
Authors: Dautant Alain , Meyer Jean-Brice , Yariv Joseph , Précigoux Gilles , Sweet Robert M. , Kalb A. Joseph , Frolow Felix 
Published: July 2002

Crystals of E. coli cytochrome b1, alias bacterioferritin, were grown from a low ionic strength solution. The resulting monoclinic P21 structure was solved by molecular replacement and refined using noncrystallographic symmetries applied to the fundamental unit, consisting of two protein subunits and a single haem. From the Patterson self-rotation results it was shown that the asymmetric unit of the monoclinic crystal consists of 12 such dimers and corresponds to a complete, nearly spherical, molecule of bacterioferritin (Mr
= 450 kDa) of 432 point-group symmetry. It is thus the most symmetrical cytochrome. As previously determined for the tetragonal form, the haem is located in a special position on a local twofold axis of the dimer. A bimetal centre is also observed within the four-helix bundle of each monomer; a metal-binding site is located on the fourfold axis.
Crystallization and preliminary X-ray analysis of B-domain fragments of a Staphylococcus aureus collagen-binding protein
Authors: Deivanayagam Champion C. S. , Rich Rebecca L. , Danthuluri Sita , Owens Rick T. , Patti Joseph M. , Höök Magnus , DeLucas Lawrence J. , Narayana Sthanam V. L. 
Published: July 2002

Recombinant proteins of monomeric and dimeric B-domain repeats of a Staphylococcus aureus FDA 574 collagen-binding adhesin have been crystallized. The single repeat unit (B1) was crystallized in a body-centered orthorhombic lattice with a = 96.9, b = 101.3, c = 120.8 Å in either the I222 or I212121 space group. These crystals diffracted to 2.5 Å resolution and the calculated Vm
values of 3.2 and 2.2 Å3 Da−1 suggest the possibility of a dimer or a trimer in the asymmetric unit. The two-repeat fragment (B1B2) crystallized in the orthorhombic space group P212121 with cell dimensions a = 42.4, b = 79.4, c = 130.4 Å and diffracted to 2.3 Å resolution. For this species, the calculated Vm
value of 2.2 Å3 Da−1 indicates the presence of a monomer in the asymmetric unit.
Crystallization and preliminary X-ray diffraction studies of blasticidin S deaminase from Aspergillus terreus
Authors: Nakasako Masayoshi , Kimura Makoto , Yamaguchi Isamu 
Published: July 2002

Blasticidin S deaminase from Aspergillus terreus was crystallized with polyethylene glycol 8000. Two types of crystals were grown under the same crystallization conditions. One type grew as thin plates, while the other had a rhombic shape. The rhombic shaped crystal was suitable for high-resolution crystal structure analysis. Precession photographs and diffraction data showed that the crystal belonged to orthorhombic space group P212121, with unit-cell dimensions a = 70.33, b = 146.56 and c = 56.48 Å. The calculated Vm
value was acceptable when a tetramer of the enzyme was contained in an asymmetric unit. Preliminary diffraction data were collected to a resolution of 2.0 Å with good statistics.
The structure of plastocyanin from the cyanobacterium Phormidium laminosum
Authors: Bond Charles S. , Bendall Derek S. , Freeman Hans C. , Guss J. Mitchell , Howe Christopher J. , Wagner Michael J. , Wilce Matthew C. J. 
Published: July 2002

The crystal structure of the `blue' copper protein plastocyanin from the cyanobacterium Phormidium laminosum has been solved and refined using 2.8 Å X-ray data. P. laminosum plastocyanin crystallizes in space group P43212 with unit-cell dimensions a = 86.57, c = 91.47 Å and with three protein molecules per asymmetric unit. The final residual R is 19.9%. The structure was solved using molecular replacement with a search model based on the crystal structure of a close homologue, Anabaena variabilis plastocyanin (66% sequence identity). The molecule of P. laminosum plastocyanin has 105 amino-acid residues. The single Cu atom is coordinated by the same residues – two histidines, a cysteine and a methionine – as in other plastocyanins. In the crystal structure, the three molecules of the asymmetric unit are related by a non-crystallographic threefold axis. A Zn atom lies between each pair of neighbouring molecules in this ensemble, being coordinated by a surface histidine residue of one molecule and by two aspartates of the other.
Crystallization of hepatitis B virus core protein shells: determination of cryoprotectant conditions and preliminary X-ray characterization
Authors: Wynne S. A. , Leslie A. G. W. , Butler P. J. G. , Crowther R. A. 
Published: July 2002

Hepatitis B virus causes liver cirrhosis and hepatocellular cancer and is a major cause of death, particularly in Asia and sub-Saharan Africa. The virus consists of an inner core or nucleocapsid, which encloses the viral nucleic acid, with an outer lipid envelope containing surface-antigen proteins. The core protein, when expressed in E. coli, assembles into spherical shells containing 180 or 240 subunits, arranged with T = 3 or T = 4 icosahedral symmetry. The C-terminal region of the protein is involved in nucleic acid binding, and deletion of this region does not prevent capsid formation. C-terminally deleted hepatitis B core shells containing 240 subunits have been crystallized and data has been collected to 3.6 Å resolution from frozen crystals, using butanediol as a cryoprotectant. The crystals have C2 symmetry, with unit-cell parameters a = 538.0, b = 353.0, c = 369.6 Å, β = 132.3°.
Crystallization of the oxygen-evolving reaction centre of photosystem II in nine different detergent mixtures
Authors: Adir Noam 
Published: July 2002

Oxygen-evolving photosystem II reaction centres (RCII) isolated from both spinach and pea have been crystallized. A single crystal form grew from RCII monomers in the presence of nine different three-component mixtures of non-ionic detergents and heptane-1,2,3-triol. The crystals grew as hexagonal rods with dimensions of up to 1 × 0.3 × 0.3 mm. The crystals diffracted to a maximum resolution of 6.5 Å and belong to a hexagonal space group with unit-cell parameters a = 495, b = 495, c = 115 Å, α = β = 90, γ = 120°. The growth of a single crystal form in the presence of such a large variety of detergents suggests a very limited range of crystal lattice formation sites in the RCII complex.