bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using southern oscillation index phases to forecast sugarcane yields: a case study for northeastern Australia
Authors: Everingham Y. L. , Muchow R. C. , Stone R. C. , Coomans D. H. 
Published: August 2003

AbstractClimate is a key driver of sugarcane productivity. Advance knowledge of the likely climate and its impact on production could add value to production, harvest and marketing efforts. A climate forecast system that incorporates five patterns or phases of the southern oscillation index is used to assess whether an early indication of sugarcane yield anomalies in Australia can be produced. Results indicate that, for certain sugarcane growing regions, the climate forecast system offers better estimates of the direction of the anomaly when compared with no climate forecast system. Improved results of the direction of the yield anomaly can be obtained some 7 months prior to the commencement of harvest. This information can then be used by marketers to plan better the customer allocations, shipping schedules and storage requirements for the next season. Advance knowledge of the crop size can also assist industry decision makers in scheduling when the harvest season should commence. Further research is required to determine if other climatic indices, such as sea surface temperatures, can improve yield estimation. Consideration also needs to be given to determining whether the magnitude and the direction of the yield anomaly can be more accurately forecasted with varying lead times. Copyright © 2003 Royal Meteorological Society
Precipitation trends in Sri Lanka since the 1870s and relationships to El Niño–southern oscillation
Authors: Malmgren Björn A. , Hulugalla Ranatunge , Hayashi Yousay , Mikami Takehiko 
Published: August 2003

AbstractThe last 130 years of fluctuations in precipitation associated with the Southwest Monsoon (summer monsoon), Northeast Monsoon (winter monsoon), First Intermonsoon, and Second Intermonsoon seasons have been analysed at 15 climate stations in Sri Lanka. Analyses of trends in the interannual seasonal series indicated statistically significant temporal changes in Southwest‐Monsoon‐related precipitation at five of the stations, with three stations showing enhanced rainfall (total of 100 mm/month over the entire time interval) and two stations a decrease in rainfall with time (total of 150 mm/month). In addition, one station experienced a decrease of both First and Second Intermonsoon rainfall over time (total of 80 mm/month). The stations showing loss of rainfall are confined to higher elevation areas and those exhibiting enhanced rainfall are located in the lowlands in the southwestern sector of Sri Lanka. None of the stations show any significant change in Northeast Monsoon precipitation through time. Most of the stations are shown to have received significantly greater amounts of Second Intermonsoon precipitation during El Niño years. The Second Intermonsoon rainfall is, on average, 70 mm/month greater during El Niño years. However, a few stations show increased Southwest Monsoon precipitation (May to September) during La Niña years. Two stations along the eastern and northern coastal areas receive, on average, between 14 and 20 mm/month more Southwest Monsoon rainfall during La Niña years than during El Niño years. Copyright © 2003 Royal Meteorological Society
Analysis and regionalization of northern European winter precipitation based on its relationship with the North Atlantic oscillation
Authors: Uvo Cintia B. 
Published: August 2003

AbstractThe relationship between the North Atlantic oscillation (NAO) and winter temperature and precipitation over northern Europe has long been known. However, its strength is variable within this region. In this paper, an analysis of the regional variability of the influence of the NAO on winter precipitation in northern Europe is developed using empirical orthogonal function analysis, cluster analysis and simple correlation. Results show that precipitation in most of the region studied is affected by the NAO, although with varying intensity. The NAO strongly influences winter precipitation along the Norwegian coast, in northern Sweden and in southern Finland. It is evident that the region on the lee side of the Scandes (the mountain chain between Norway and Sweden) is protected from the effects of the moist western winds from the Atlantic that, in turn, are strongly related to the NAO. As a result, precipitation in this shielded area is mainly related to southeasterly winds. Copyright © 2003 Royal Meteorological Society
On measuring quality of a probabilistic commodity forecast for a system that incorporates seasonal climate forecasts
Authors: Potgieter A. B. , Everingham Y. L. , Hammer G. L. 
Published: August 2003

AbstractRegional commodity forecasts are being used increasingly in agricultural industries to enhance their risk management and decision‐making processes. These commodity forecasts are probabilistic in nature and are often integrated with a seasonal climate forecast system. The climate forecast system is based on a subset of analogue years drawn from the full climatological distribution. In this study we sought to measure forecast quality for such an integrated system. We investigated the quality of a commodity (i.e. wheat and sugar) forecast based on a subset of analogue years in relation to a standard reference forecast based on the full climatological set. We derived three key dimensions of forecast quality for such probabilistic forecasts: reliability, distribution shift, and change in dispersion. A measure of reliability was required to ensure no bias in the forecast distribution. This was assessed via the slope of the reliability plot, which was derived from examination of probability levels of forecasts and associated frequencies of realizations. The other two dimensions related to changes in features of the forecast distribution relative to the reference distribution. The relationship of 13 published accuracy/skill measures to these dimensions of forecast quality was assessed using principal component analysis in case studies of commodity forecasting using seasonal climate forecasting for the wheat and sugar industries in Australia. There were two orthogonal dimensions of forecast quality: one associated with distribution shift relative to the reference distribution and the other associated with relative distribution dispersion. Although the conventional quality measures aligned with these dimensions, none measured both adequately. We conclude that a multi‐dimensional approach to assessment of forecast quality is required and that simple measures of reliability, distribution shift, and change in dispersion provide a means for such assessment. The analysis presented was also relevant to measuring quality of probabilistic seasonal climate forecasting systems. The importance of retaining a focus on the probabilistic nature of the forecast and avoiding simplifying, but erroneous, distortions was discussed in relation to applying this new forecast quality assessment paradigm to seasonal climate forecasts. Copyright © 2003 Royal Meteorological Society
Surface meshing using a geometric error estimate
Authors: Frey P. J. , Borouchaki H. 
Published: August 2003

AbstractIn this paper we discuss an a posteriori interpolation error estimate based on the Hessian of the surface and we propose a new geometric error estimate related to the local deformation of the surface. The new approach makes possible the construction of adapted geometric meshes for surfaces by specifying the element sizes (and directions) so as to bound the error below a user‐given threshold value. The surfaces considered here are Cartesian surfaces. An analytical example is provided so as to emphasize the potential of the approach. Copyright © 2003 John Wiley & Sons, Ltd.
Improving the quality of meshes for the simulation of semiconductor devices using Lepp‐based algorithms
Authors: Hitschfeld N. , Villablanca L. , Krause J. , Rivara M. C. 
Published: August 2003

AbstractThis paper discusses a new post‐process algorithm for generating valid Delaunay meshes for the Box‐method (finite‐volume method) as required in semiconductor device simulation. In such an application, the following requirements must be considered: (i) in critical zones of the device, edges aligned with the flow of the current (anisotropic meshes) are needed; (ii) boundary and interface triangles with obtuse angles opposite to the boundary/interfaces are forbidden; (iii) large obtuse angles in the interior of the device must be destroyed and (iv) interior vertices with high vertex‐edge connectivity should be avoided. By starting from a fine Delaunay mesh that satisfies condition (i), the algorithm produces a Delaunay mesh that fully satisfies condition (ii) and satisfies conditions (iii) and (iv) according to input tolerance parameters γ and c, where γ is a maximum angle tolerance value and c is a maximum vertex‐edge connectivity tolerance value. Both to destroy any target interior obtuse triangle t and any target high vertex‐edge connectivity, a Lepp–Delaunay algorithm is used. The elimination of obtuse angles opposite to the boundary and/or interfaces is done either by longest edge bisection or by the generation of isosceles triangles. The Lepp–Delaunay algorithm allows a natural improvement of the input mesh by inserting a few points in some existing edges of the current triangulation. Examples of the use of the algorithm over Delaunay constrained meshes generated by a normal offsetting approach will be shown. A comparison with an orthogonal refinement method followed by Voronoi point insertion is also included. Copyright © 2003 John Wiley & Sons, Ltd.
Domain decomposition approach for parallel unstructured mesh generation
Authors: Larwood B. G. , Weatherill N. P. , Hassan O. , Morgan K. 
Published: August 2003

AbstractIn this paper, a method to generate large unstructured meshes on parallel computers is demonstrated. Using the Message Passing Interface, a coarse‐grained parallel harness has been developed, that allows the use of sequential generators in a parallel environment. Meshes of over 500 million elements will be shown. Copyright © 2003 John Wiley & Sons, Ltd.
A new indirect anisotropic quadrilateral mesh generation scheme with enhanced local mesh smoothing procedures
Authors: Lee Y. K. , Lee C. K. 
Published: August 2003

AbstractAn enhanced version of indirect advancing front technique is proposed for the construction of full quadrilateral anisotropic meshes on 3D surfaces. The final quadrilateral mesh is constructed from a background triangular mesh and the merging procedure is carried out in the parametric space. The proposed method employed the systemic merging technique for the formation of quadrilaterals and the metric specifications for controlling the anisotropic characteristics of the elements. In order to generate well‐graded anisotropic quadrilaterals, the selection criteria of base segment for merging are carefully defined. Furthermore, in order to improve the shape quality of the final mesh, a set of new local smoothing algorithms for anisotropic quadrilateral mesh quality enhancement has been proposed and tested in this study. Numerical examples obtained indicate that the proposed enhanced local smoothing schemes can effectively improve the quality of the quadrilateral meshes produced and increase the robustness of the mesh generation scheme. Copyright © 2003 John Wiley & Sons, Ltd.
Multiple material marching cubes algorithm
Authors: Wu Ziji , Sullivan John M. 
Published: August 2003

AbstractThe accurate reconstruction of three‐dimensional (3D) boundary surfaces from two‐dimensional (2D) medical images is a crucial procedure in most applications of computational biomedical engineering. This paper addresses an innovative system that efficiently reconstructs accurate, multiple‐material, 3D surface meshes from 2D medical images. It is based on an enhanced marching cubes algorithm, the multi‐material marching cubes algorithm (M3C), which extracts boundary surfaces between different materials within one sweep of the image stack in an integrated manner. The continuity and integrity of the surfaces are ensured with this robust algorithm. Surface adjustment algorithms were also revised to adapt to the multiple‐material nature of the system. Copyright © 2003 John Wiley & Sons, Ltd.
New view on cerebellar cortical background activity in rat: simulation
Authors: Kalauzi A. , Ćulić M. , Martać Lj. , Grbić G. , S̆aponjić J. , Jovanović A. , Janković B. , Spasić S. 
Published: August 2003

AbstractThe aim of this study was to reveal the nature and meaning of interspike background activity (RBA) recorded in Prukinje cell layer of rat cerebellum. We compared Fourier amtplitude spectra of recorded, extracted and averaged simple spike(s)—SS and complex spike(s)—CS with the mean amplitude spectrum of the remaining interspike RBA. A much greater similarity of spectral characteristics was noticed between SS and RBA, than between CS and RBA. Then, we simulated background activity (SBA), by superimposing averaged SS with randomized amplitudes and time delays. There was a significant correlation (p<0.005) between linearly transformed simulated and recorded amplitude spectra. Mean amplitude spectra of SBA were positively correlated with the number of superimposed SS. We propose to use this fact as a qualitative indication about the direction of change in the mean activity of surrounding neuronal population.
General‐base catalysed hydrolysis and nucleophilic substitution of activated amides in aqueous solutions
Authors: Buurma Niklaas J. , Blandamer Michael J. , Engberts Jan B. F. N. 
Published: August 2003

AbstractThe reactivity of 1‐benzoyl‐3‐phenyl‐1,2,4‐triazole (1a) was studied in the presence of a range of weak bases in aqueous solution. A change in mechanism is observed from general‐base catalysed hydrolysis to nucleophilic substitution and general‐base catalysed nucleophilic substitution. A slight tendency is also observed for the more hydrophobic general bases to show higher reactivity towards 1a. Aspartame is an effective nucleophile, possibly because nucleophilic substitution is subject to intramolecular general‐base catalysis. A general conclusion derived from the present results is that unexpected rate effects can only be rationalised provided that the detailed reaction mechanisms are well understood. Copyright © 2003 John Wiley & Sons, Ltd.
Reactivity of heterophospholes toward 1,3‐dipolar cycloaddition of diazo compounds—an FMO analysis
Authors: Jikyo Tamaki , Schatz Jürgen , Maas Gerhard 
Published: August 2003

AbstractThe molecular geometries and the frontier orbital energies of three diazo compounds [diazodiphenylmethane (2), the α‐silyl‐α‐diazoketone 3 and the isomeric 2‐siloxy‐1‐diazoalkene 4], 10 heterophospholes with a PC bond and two heterophospholes with a PN bond were obtained from DFT calculations at the B3LYP/6–311+G** level. The 1,3‐dipolar cycloaddition reactivity of diazo compounds 2–4 toward the heterophospholes is discussed on the basis of FMO theory. It is concluded that in most cases, the dominant frontier orbital interaction is between the HOMO(diazo) and the LUMO(heterophosphole), and that the reactivity should decrease in the order­2 >4 >3. The 1,2‐thiaphosphole 9 and 1,3‐azaphosphole 10 have HOMOs of high energy and, therefore, the HOMO(heterophosphole)–LUMO(diazo) interaction is also important. Among the different types of heterophos‐pholes considered here, the 2‐acyl‐1,2,3‐diazaphosphole 5, 3H‐1,2,3,4‐triazaphosphole 8, 1,2‐thiaphosphole 9 and 1,3,4‐thiazaphosphole 14 are predicted to have the highest dipolarophilic reactivities. These conclusions are in qualitative agreement with available experimental results. Copyright © 2003 John Wiley & Sons, Ltd.
N‐Isopropyl enols of carboxylic acid amides
Authors: Lei Yi Xiong , Casarini Daniele , Cerioni Giovanni , Rappoport Zvi 
Published: August 2003

AbstractEight N‐isopropyl compounds of the formal structure YY′CHCONHPr‐i (6), Y,Y′ = CO2Me, CO2CH2CF3, CN; YY′ = Meldrum′s acid residue; Y = CO2Me, Y′ = CO2CH2CF3, CN; Y = CO2CH2CF3, CO2CH(CF3)2, Y′ = CN, and the N‐t‐butyl derivative of Meldrum's acid were prepared and their structures were investigated in the solid state and in solution. The x‐ray diffraction data indicate that in the solid state the structure is that of the amide 6, when Y = Y′ = CO2Me, whereas when Y = CO2Me, Y′ = CN or YY′ = Meldrum′s acid residue the structure is that of the enol (5) YY′C=C(OH)NHPr‐i. The solid‐state 13C spectra indicate structure 6 when Y = CO2Me, Y′ = CO2R, R = Me, CH2CF3 and an enol structure for the other compounds studied. 1H, 13C and when available 19F NMR spectra showed that the enol/amide composition in solution is structure and solvent dependent, in analogy with the previously investigated N‐Ph analogs. The percentage of enol (and KEnol) decrease in the order of solvents CCl4 > CDCl3 > THF‐d8 > CD3CN > DMSO‐d6, DMF‐d7. For Y,Y′ the percentage of enol increases when the number of fluorine atoms in R of the CO2R increases, when CN replaces a CO2R group or for the cyclic Meldrum's acid derivative. Both E‐ and Z‐enols were observed when Y ≠ Y′, mostly at low temperature. The δ(OH) values increase with increased polarity of the medium and with increased strength of the hydrogen bonds in which they are involved. In THF‐d8 and DMF‐d7 the Z‐enol/E‐enol and the amide/enol ratios increase with increase in temperature. A main conclusion from the work is that the percentage of the enol increases, but not drastically, when the N‐substituent is changed from Ph to i‐Pr. Copyright © 2003 John Wiley & Sons, Ltd.
Generation of a cyclopentenyl cation labelled with a single deuterium at C‐4. Rate studies of the scrambling reaction
Authors: Brunelle Patrick , Sorensen Ted S. , Taeschler Christoph 
Published: August 2003

AbstractThe kinetics of the hydrogen scrambling reaction in the cyclopentenyl cation 1 were studied. The pure 4‐deutero derivative of 1 was prepared using superacid conditions and the activation energy ΔG‡ for the rearrangement of this label to the C‐1(3) position of 1 was determined using low‐temperature 2H NMR spectroscopy. In addition, the sequential rearrangement of the deuterium label from C‐4(5) → C‐1(3) → C‐2 was noted in a qualitative fashion. Based on a statistical analysis, the activation free energy ΔG‡ for a single hydrogen (deuterium) migration leading to the 4‐cyclopentenyl cation intermediate was determined to be 18.3 kcal mol−1 (−20.8 °C), in good agreement with the less direct determination provided by an earlier NMR line‐broadening and spin‐saturation transfer experiment. Copyright © 2003 John Wiley & Sons, Ltd.
NMR Spectroscopic and quantum chemical characterization of the (E )− and (Z )− isomers of the penta‐1,3‐dienyl‐2‐cation
Authors: Siehl Hans‐Ullrich , Müller Thomas , Gauss Jürgen 
Published: August 2003

AbstractDilute solutions of the (E )− and (Z )− isomers of pent‐1,3‐dienyl‐2‐cations (1) were obtained from reaction of 4‐chloro‐1,2‐pentadiene (2) with SbF5 in SO2ClF/SO2F2 at −135 °C using high‐vacuum co‐condensation techniques. The experimental NMR spectra of the mixture of the two isomers were compared with quantum chemical 13C NMR chemical shift calculations at HF‐SCF, MP2, CCSD and CCSD(T) levels using MP2/tzp geometries. Quantum chemical shift calculations were performed with a tzp basis (9s5p1d/5s3p1d) for carbon and a dz basis (4s/2s) for hydrogen using gauge‐including atomic orbitals (GIAOs). The HF‐SCF calculations deviate significantly for the positively charged carbon atoms of the allyl‐type resonance system showing up to 40 ppm too deshielded values compared with the experimentally observed chemical shifts. The HF‐SCF approach is therefore not sufficient in predicting satisfactorily the shielding tensors in this type of carbocation. Inclusion of electron correlation, however, allows an unequivocal assignment of the spectra of the Z‐ and E‐isomers. The mean deviation between experimental and calculated NMR chemical shifts at the CCSD(T) level is 1.8 and 2.0 ppm for (Z)‐ and (E)‐1, respectively. The dienyl cations (E/Z)‐1 are the smallest vinyl cations ever generated as persistent species in superacidic solutions and observed by 13C NMR spectroscopy. These carbocations were structurally fully characterized by advanced ab initio quantum chemical calculations of structure and NMR chemical shifts. Copyright © 2003 John Wiley & Sons, Ltd.
Structure‐Activity Relationships for the Toxicity of Substituted Poly‐hydroxylated Benzenes to Tetrahymena pyriformis: Influence of Free Radical Formation
Authors: Netzeva Tatiana I. , Aptula Aynur O. , Chaudary Shaqil H. , Duffy Judith C. , Wayne Schultz T. , Schüürmann Gerrit , Cronin Mark T. D. 
Published: August 2003

AbstractThe aim of this study was to develop quantitative structure‐activity relationships for the toxicity to Tetrahymena pyriformis of 30 substituted poly‐hydroxylated benzenes. Physico‐chemical descriptors for the expression of free radical formation, associated with the OH moiety on the aromatic ring, were calculated. These included one‐electron equilibrium constants that did and did not account for the oxidation of an OH‐group, homolytic bond dissociation energy (BDE), electronegativity (EN) and absolute hardness (AH), in addition to the distribution coefficient (log D) as a measure of hydrophobicity. The reactivity descriptors were calculated using the semi‐empirical AM1 Hamiltonian in the MOPAC molecular orbital software. Statistically significant two‐parameter QSARs for toxicity were obtained by combination of log D with either BDE or AH. The QSARs suggested that toxicity is associated with hydrophobicity and the probability of radical formation.
Coalescing times for IID random variables with applications to population biology
Authors: Adler Ilan , Ahn Hyun‐Soo , Karp Richard M. , Ross Sheldon M. 
Published: August 2003

AbstractWe consider a coalescing particle model where particles move in discrete time. At each time period, each remaining ball is independently put in one of n bins according to a probability distribution p = (p1, …, pn), and all balls put into the same bin merge into a single ball. Starting with k balls, we are interested in the properties of E[N(p, k)], the expected time until all balls merge into one. We derive both upper and lower bounds for E[N(p, k)], some asymptotic results, and show that P{N(p, k) > t}, and thus E[N(p, k)], is a Schur concave function of p. Applications to population biology are noted. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 23: 155–166, 2003
Proof of a tiling conjecture of Komlós
Authors: Shokoufandeh Ali , Zhao Yi 
Published: August 2003

AbstractA conjecture of Komlós states that for every graph H, there is a constant K such that if G is any n‐vertex graph of minimum degree at least (1 − (1/χcr(H)))n, where χcr(H) denotes the critical chromatic number of H, then G contains an H‐matching that covers all but at most K vertices of G. In this paper we prove that the conjecture holds for all sufficiently large values of n. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 23: 180–205, 2003