bluuebunny/crossref_metadata_2025_split huggingface dataset:
Clear air turbulence over South Africa
Authors: de Villiers M P , van Heerden J 
Published: July 2002

AbstractClear air turbulence (CAT) at high altitude remains a hazard to aviation which can result in passenger injury and aircraft damage. Two limited surveys of CAT events over South Africa, 1993–1995 (inclusive) and 1998, are used to illustrate the most likely synoptic conditions under which CAT can be expected. A case study of CAT associated with an upper‐air trough and a mountain wave is presented. The study also evaluates the effectiveness of the Ellrod Turbulence Index (ETI) derived from model data provided by the UK Met. Office. A forecast of ETI derived from the Global Spectral Model of the United States National Center for Environmental Prediction (NCEP) is also reviewed. Copyright © 2001 Royal Meteorological Society
Meteorological and geo‐orographical relationships with lightning activity in Castilla‐Leon (Spain)
Authors: Rivas Soriano L J , De Pablo F , Garcia Diez E L 
Published: July 2002

AbstractSome meteorological and geo‐orographical factors related to cloud‐to‐ground flashes in Castilla‐Leon (Spain) are studied. The relationship between flash density and the number of days with thunderstorms (thunderdays) is analysed, and a clear dependence and geographical variability is found. It is also shown that flashes have an average delay of four hours with respect to the time of the beginning of convection. The effect on flashes of dry static instability and moisture content is analysed by classifying days into four types according to the average values of the 850–700 hPa temperature difference and the 850 hPa dew‐point temperature. A similar classification using the 700 hPa wind direction is used to analyse the effect of the mean‐level flow on flashes. The results suggest that the daily number of flashes is mainly affected by the moisture content. Finally, a relationship between the cloud‐to‐ground flash density and geo‐orographical factors (altitude, latitude and longitude) is deduced using multiple linear analysis. Copyright © 2001 Royal Meteorological Society
A diagnostic study on the improvement in tropical cyclone motion prediction by the UK Meteorological Office Global Model
Authors: Chan Johnny C L , Kwok Roger H F 
Published: July 2002

AbstractThe UK Meteorological office introduced a new bogussing scheme for tropical cyclone (TC) motion prediction in its global model in October 1994 after a series of tests. Before the operational implementation of this scheme, a 19‐day period (in August and September 1994) was selected during which both the new and the old schemes were run operationally in parallel for a total of 12 TCs in three ocean basins. Comparisons between the forecast errors of the schemes demonstrated the superiority of the new scheme at all forecast time periods (Heming et al., 1995). This paper presents the results of an investigation into the possible reasons for the improved predictions by the new scheme during this trial period. All three factors of the new scheme (an improved initial positioning of the TC, an imposed steering flow derived from the past 6‐h motion of the TC and an empirical vortex structure determined from actual observations and TC warning bulletins) are found to contribute towards the improvement. In particular, a good initial position together with an appropriate steering produce a much better 24‐h forecast. For the 48‐ and 72‐h forecasts, the steering flow remains an important factor and the contribution of the vortex structure also becomes significant in some cases. The steering flow appears to be the most crucial factor in determining the accuracy of the model predictions. Copyright © 1997 Royal Meteorological Society.
Commercialisation in the provision of meteorological services in New Zealand
Authors: Steiner J Thomas , Martin John R , Gordon Neil D , Grant Malcolm A 
Published: July 2002

AbstractThere have been significant reforms in New Zealand of government management in general and of the science and transport sectors in particular. The impact of the reforms on the provision of meteorological services is discussed as an example of the application of the general reform thrust to a specialist technical area. The eventual outcome was the establishment of Meteorological Service of New Zealand Ltd (MetService) as a commercial company, trading in the weather forecasting market but remaining under Crown ownership. At the same time the National Institute of Water and Atmosphere (NIWA) was established. It includes the climatic responsibilities and much of the scientific research component of the former NZMS. It too operates commercially and is Crown owned. Unlike MetService, NIWA is not required to return a dividend to its owners. The procedures leading to the establishment of these new organisations, their mode of operation and their initial successful performance are described. Copyright © 1997 Royal Meteorological Society
Developments in aviation forecasting in the UK
Authors: Hall B A 
Published: July 2002

AbstractThe main developments in aviation forecasting over the 50 years up to 1985 are summarised. The importance of subsequent increasing Regional and World Area Forecasting commitments at the UK Meteorological Office is stressed, along with a demonstration of the more recent advances in forecasting low‐level and middle/upper‐level significant weather, respectively. Meteorological hazards requiring warnings (e.g. SIGMETS) and current aviation forecast output are considered, along with a glance into the future, cautioning that the trend towards fully automated products may be hindered by slower improvements in some aspects of model technology such as derived‐field forecasts of fog and low cloud. Copyright © 1998 Royal Meteorological Society
An autonomous approach to road temperature prediction
Authors: Hertl Stefan , Schaffar Gottfried 
Published: July 2002

AbstractTo provide ice warnings for road maintenance, a forecasting model has been developed that computes the state of the road several hours in advance. The model, which is called HS4Cast, runs autonomously and does not need human input. The current version of the forecast model features a fuzzy logic engine that determines the best forecast by evaluating certain patterns in the measured parameters. Using this forecast engine, predictions up to 24 hours in advance are possible with reasonable accuracy. If available, additional forecasts from a weather centre may be imported into the model so that the effects of precipitation are taken into account, this further reduces forecast errors. Statistics summarising the model's performance are presented using data from several measurement sites along an Austrian motorway, where HS4Cast has been in use since about 1990. Copyright © 1998 Royal Meteorological Society
Numerical simulation of two heavy rainfall events over coastal southeastern Australia
Authors: Speer Milton S , Leslie Lance M 
Published: July 2002

AbstractPredicting rainfall along the New South Wales (NSW) coast is a major forecasting problem because of sharp gradients in rainfall amounts with the heaviest falls on the coastal fringe decreasing rapidly inland. On some occasions the rainfall pattern is less spatially coherent and consists of isolated maxima. Both rainfall patterns are associated with mesoscale coastal ridging. The first rainfall pattern arises from coastal ridging occurring in combination with an offshore trough. In the first case study presented here, a typical ridge–trough system was aligned parallel to the coast, and located just offshore, with the observed rainfall heaviest at the coast, decreasing rapidly from over 60 mm to near zero 30 km inland. The model captured well the southward temporal evolution of the maximum relative humidity values and rainfall. The second rainfall pattern occurs when shallow coastal ridging interacts with downdrafts from thunderstorm activity over the ranges to the west. The second case study was one in which convergence and condensation generated a quasi‐stationary line of thunderstorms, resulting in flash flooding. The model precipitation rates and accumulations matched very closely those of the squall line, as revealed by radar precipitation intensities and the observed rainfall. Copyright © 1998 Royal Meteorological Society
Statistical relationship between aerological data and daily precipitation at Buenos Aires
Authors: Ruiz N E , Vargas W M 
Published: July 2002

AbstractThe basic statistics of aerological variables obtained from radiosonde data at Ezeiza, Buenos Aires, Argentina, for 1986 are examined, and their relationships with occurrence and non‐occurrence of daily local precipitation are analysed. The resulting samples are statistically different for nearly all the variables. Nevertheless, thermodynamic variables at the 700 mb level and the K‐Whiting instability index yield the best correlations with rainfall, though it is noted that they are diagnostic and not prognostic variables. 500 mb relative vorticity at selected gridpoints is included in the analysis, given the effectiveness of this dynamic field to recognise favourable patterns for daily precipitation occurrence. Some experiments using these potential predictors to specify occurrence or non‐occurrence of the event within a 24‐hour period are presented. Copyright © 1998 Royal Meteorological Society
Applications of the NERC MST radar facility in mesoscale studies
Authors: Thomas L 
Published: July 2002

AbstractThe NERC radar facility located near Aberystwyth (52.4°N,4.1°W) was established for remote sensing of the structure and dynamics of the mesosphere, stratosphere and troposphere; hence the name MST radar. The facility records scatter and reflection from metre‐scale irregularities in refractive index produced by atmospheric waves and turbulence. The measurement of the three‐dimensional wind field at tropospheric and lower stratospheric heights represents the primary capability of the facility and is expected to be particularly useful in short‐range local weather forecasting operations. At the same time, the temporal and height resolution achievable lend themselves to studies of smaller‐scale, time‐varying phenomena, such as waves and turbulence. Particular attention has been paid to the characteristics and vertical propagation of mountain waves and inertia‐gravity waves, and estimates made of the vertical flux of horizontal momentum associated with such waves, known to play a significant role in the large‐scale atmospheric circulation. The turbulence associated with the dissipation of these waves, and also generated in the vicinity of jet streams, has also been examined. Quasi‐specular reflection of radar waves associated with changes in temperature gradients has helped monitor the height and sharpness of the tropopause and also the structure of frontal zones. The technical capabilities of the facility and the continuity of data provided by its all‐weather and extended operation have been shown to be well suited to both mesoscale meteorological and research applications. Copyright © 1999 Royal Meteorological Society
Host-based genotype variation in insects revisited
Authors: Lushai G. , Markovitch O. , Loxdale H.D. 
Published: July 2002

AbstractElucidation of the genetic variability of a model insect species, the grain aphid, Sitobion avenae (Fabricius), a predominantly asexual herbivore within the temperate agro-ecosystem tested, was initiated using molecular DNA markers (RAPDs). This revealed genetic profiles that appeared related to host adaptation at the specific level amongst the natural populations colonizing different grasses and cereals (Poaceae) within the same geographic location. These profiles were recorded either as ‘specialist’genotypes found on specific grasses, or as ‘generalist’ genotypes colonizing several host types including cultivated cereals or native grasses. These findings are compared with analogous systems found amongst insect species, including at a higher trophic level, i.e. interactions between hymenopterous aphid parasitoids. As the aphids and their respective plant hosts occur in the same geographical region at the same time, this appears to be a rare example of the evolutionary transition leading to sympatric speciation in insects. Hence, this study highlights the importance of understanding not only the demographic parameters to genetic diversity, but also the more intricate correlation of genetic diversity to host types in agricultural environments.
Transgenic Expression in Arabidopsis of a Polyprotein Construct Leading to Production of Two Different Antimicrobial Proteins
Authors: François Isabelle E.J.A. , De Bolle Miguel F.C. , Dwyer Geoff , Goderis Inge J.W.M. , Woutors Piet F.J. , Verhaert Peter D. , Proost Paul , Schaaper Wim M.M. , Cammue Bruno P.A. , Broekaert Willem F. 
Published: July 2002

Abstract
We developed a method for expression in Arabidopsis of a transgene encoding a cleavable chimeric polyprotein. The polyprotein precursor consists of a leader peptide and two different antimicrobial proteins (AMPs), DmAMP1 originating from Dahlia merckiiseeds and RsAFP2 originating from Raphanus sativusseeds, which are linked by an intervening sequence (“linker peptide”) originating from a natural polyprotein occurring in seed ofImpatiens balsamina. The chimeric polyprotein was found to be cleaved in transgenic Arabidopsis plants and the individual AMPs were secreted into the extracellular space. Both AMPs were found to exert antifungal activity in vitro. It is surprising that the amount of AMPs produced in plants transformed with some of the polyprotein transgene constructs was significantly higher compared with the amount in plants transformed with a transgene encoding a single AMP, indicating that the polyprotein expression strategy may be a way to boost expression levels of small proteins.
Gibberellin Signaling in Barley Aleurone Cells. Control of SLN1 and GAMYB Expression
Authors: Gubler Frank , Chandler Peter Michael , White Rosemary G. , Llewellyn Danny J. , Jacobsen John V. 
Published: July 2002

Abstract
We have previously identified GAMYB, a gibberellin (GA)-regulated transcriptional activator of α-amylase gene expression, in aleurone cells of barley (Hordeum vulgare). To examine the regulation of GAMYB expression, we describe the use of nuclear run-on experiments to show that GA causes a 2-fold increase in the rate of GAMYB transcription and that the effect of GA can be blocked by abscisic acid (ABA). To identify GA-signaling components that regulate GAMYB expression, we examined the role of SLN1, a negative regulator of GA signaling in barley. SLN1, which is the product of the Sln1(Slender1) locus, is necessary for repression of GAMYB in barley aleurone cells. The activity of SLN1 in aleurone cells is regulated posttranslationally. SLN1 protein levels decline rapidly in response to GA before any increase in GAMYB levels. Green fluorescent protein-SLN1 fusion protein was targeted to the nucleus of aleurone protoplasts and disappeared in response to GA. Evidence from a dominant dwarf mutant at Sln1, and from thegse1 mutant (that affects GA “sensitivity”), indicates that GA acts by regulating SLN1 degradation and not translation. Mutation of the DELLA region of SLN1 results in increased protein stability in GA-treated layers, indicating that the DELLA region plays an important role in GA-induced degradation of SLN1. Unlike GA, ABA had no effect on SLN1 stability, confirming that ABA acts downstream of SLN1 to block GA signaling.
Regulated Copper Uptake in Chlamydomonas reinhardtii in Response to Copper Availability
Authors: Hill K. L. , Hassett R. , Kosman D. , Merchant S. 
Published: July 2002

Abstract
A saturable and temperature-dependent copper uptake pathway has been identified in Chlamydomonas reinhardtii. The uptake system has a high affinity for copper ions (Km approximately 0.2 [mu]M) and is more active in cells that are adapted to copper deficiency than to cells grown in a medium containing physiological (submicromolar to micromolar) copper ion concentrations. The maximum velocity of copper uptake by copper-deficient cells (169 pmol h-1 106 cells-1 or 62 ng min-1 mg-1 chlorophyll) is up to 20-fold greater than that of fully copper-supplemented cells, and the Km (approximately 2 x 102 nM) is unaffected. Thus, the same uptake system appears to operate in both copper-replete and copper-deficient cells, but its expression or activity must be induced under copper-deficient conditions. A cupric reductase activity is also increased in copper-deficient compared with copper-sufficient cells. The physiological characteristics of the regulation of this cupric reductase are compatible with its involvement in the uptake path-way. Despite the operation of the uptake pathway under both copper-replete and copper-deficient conditions, C. reinhardtii cells maintained in fully copper-supplemented cells do not accumulate copper in excess of their metabolic need. These results provide evidence for a homeostatic mechanism for copper metabolism in C. reinhardtii.
An Intracellular Signal Transduction Pathway between the Chloroplast and Nucleus Is Involved in De-Etiolation
Authors: Mochizuki N. , Susek R. , Chory J. 
Published: July 2002

Abstract
Chloroplast development requires the coordinated expression of nuclear and chloroplastic genes. A hypothesized signal from the chloroplast couples the transcription of certain nuclear genes encoding photosynthetic proteins with chloroplast function. We have previously described an Arabidopsis thaliana mutant, gun1, which has a defect in the signal transduction pathway coupling such nuclear and plastidic gene expression. Here we show that gun1 seedlings are also defective in establishing photoautotrophic growth. gun1 seedlings develop normally in the dark, but, based on morphological criteria and the kinetics of chlorophyll accumulation, photosynthetic mRNA accumulation, and the differentiation of etioplasts to chloroplasts, are retarded in their ability to de-etiolate. Therefore, we propose that the GUN1 gene plays an important role in the transition from heterotrophic to photoautotrophic growth, suggesting an important physiological role for the plastid-nucleus signaling pathway during chloroplast biogenesis.
The Sorghum Photoperiod Sensitivity Gene, Ma3, Encodes a Phytochrome B
Authors: Childs K. L. , Miller F. R. , Cordonnier-Pratt M. M. , Pratt L. H. , Morgan P. W. , Mullet J. E. 
Published: July 2002

Abstract
The Ma3 gene is one of six genes that regulate the photoperiodic sensitivity of flowering in sorghum (Sorghum bicolor [L.] Moench). The ma3R mutation of this gene causes a phenotype that is similar to plants that are known to lack phytochrome B, and ma3R sorghum lacks a 123-kD phytochrome that predominates in light-grown plants and that is present in non-ma3R plants. A population segregating for Ma3 and ma3R was created and used to identify two randomly amplified polymorphic DNA markers linked to Ma3. These two markers were cloned and mapped in a recombinant inbred population as restriction fragment length polymorphisms. cDNA clones of PHYA and PHYC were cloned and sequenced from a cDNA library prepared from green sorghum leaves. Using a genome-walking technique, a 7941-bp partial sequence of PHYB was determined from genomic DNA from ma3R sorghum. PHYA, PHYB, and PHYC all mapped to the same linkage group. The Ma3- linked markers mapped with PHYB more than 121 centimorgans from PHYA and PHYC. A frameshift mutation resulting in a premature stop codon was found in the PHYB sequence from ma3R sorghum. Therefore, we conclude that the Ma3 locus in sorghum is a PHYB gene that encodes a 123-kD phytochrome.
Mutations in the Small Subunit of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Increase the Formation of the Misfire Product Xylulose-1,5-Bisphosphate
Authors: Flachmann R. , Zhu G. , Jensen R. G. , Bohnert H. J. 
Published: July 2002

Abstract
The small subunit (S) increases the catalytic efficiency of ribulose-1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) by stabilizing the active sites generated by four large subunit (L) dimers. This stabilization appears to be due to an influence of S on the reaction intermediate 2,3-enediol, which is formed after the abstraction of a proton from the substrate ribulose-1,5-bisphosphate. We tested the functional significance of residues that are conserved among most species in the carboxy-terminal part of S and analyzed their influence on the kinetic parameters of Synecho-coccus holoenzymes. The replacements in S (F92S, Q99G, and P108L) resulted in catalytic activities ranging from 95 to 43% of wild type. The specificity factors for the three mutant enzymes were little affected (90–96% of wild type), but Km(CO2) values increased 0.5- to 2-fold. Mutant enzymes with replacements Q99G and P108L showed increased mis-protonation, relative to carboxylation, of the 2,3-enediol intermediate, forming 2 to 3 times more xylulose-1,5-bisphosphate per ribulose-1,5-bisphosphate utilized than wild-type or F92S enzymes. The results suggest that specific alterations of the L/S interfaces and of the hydrophobic core of S are transmitted to the active site by long-range interactions. S interactions with L may restrict the flexibility of active-site residues in L.
Molecular Cloning and Further Characterization of a Probable Plant Vacuolar Sorting Receptor
Authors: Paris N. , Rogers S. W. , Jiang L. , Kirsch T. , Beevers L. , Phillips T. E. , Rogers J. C. 
Published: July 2002

Abstract
BP-80 is a type I integral membrane protein abundant in pea (Pisum sativum) clathrin-coated vesicles (CCVs) that binds with high affinity to vacuole-targeting determinants containing asparagine-proline-isoleucine-arginine. Here we present results from cDNA cloning and studies of its intracellular localization. Its sequence and sequences of homologs from Arabidopsis, rice (Oryza sativa), and maize (Zea mays) define a novel family of proteins unique to plants that is highly conserved in both monocotyledons and dicotyledons. The BP-80 protein is present in dilated ends of Golgi cisternae and in “prevacuoles,” which are small vacuoles separate from but capable of fusing with lytic vacuoles. Its cytoplasmic tail contains a Tyr-X-X-hydrophobic residue motif associated with transmembrane proteins incorporated into CCVs. When transiently expressed in tobacco (Nicotiana tabacum) suspension-culture protoplasts, a truncated form lacking transmembrane and cytoplasmic domains was secreted. These results, coupled with previous studies of ligand-binding specificity and pH dependence, strongly support our hypothesis that BP-80 is a vacuolar sorting receptor that trafficks in CCVs between Golgi and a newly described prevacuolar compartment.
Expression and Characterization of Pea Chloroplastic Glyceraldehyde-3-Phosphate Dehydrogenase Composed of Only the B-Subunit
Authors: Li A. D. , Anderson L. E. 
Published: July 2002

Abstract
A cDNA fragment coding for the pea (Pisum sativum L.) chloroplastic glyceraldehyde-3-P dehydrogenase (EC 1.2.1.13) B-subunit and a truncated form corresponding in length to the A-subunit have been cloned into an expression vector, expressed in the absence of the A-subunit in a gap- Escherichia coli strain, purified, and studied. Like the isolated enzyme from higher plant chloroplasts, the recombinant enzymes have dual specificity for NADPH and NADH. The recombinant glyceraldehyde-3-P dehydrogenases have the same optimal pH as the enzyme isolated from pea chloroplasts. Like the native chloroplast enzyme, the recombinant B-subunit has a marked tendency to form large aggregates, whereas the truncated B-subunit exists as the tetramer. The recombinant B-subunit glyceraldehyde 3-P dehydrogenase is more sensitive to dithiothreitol than its truncated form. It seems likely that a different pair of cysteines is responsible for the redox sensitivity of the activity of the enzyme composed of B-subunits than the cysteine residues implicated in the modulation of the activity of the enzyme composed of A-subunits by previous work in this laboratory.