bluuebunny/crossref_metadata_2025_split huggingface dataset:
The development of the genital ducts in Limnodriloidinae (Tubificidae, Clitellata)
Authors: Gustavsson Lena M. 
Published: July 2002

AbstractThe development of the male duct and spermatheca is studied in three species of the marine Limnodriloidinae (Tubificidae): Limnodriloides rubicundus; Tectidrilus bori; Thalassodrilides ineri. All tubificids are hermaphroditic with paired male ducts, female ducts and, as a rule, spermathecae. The male duct comprises a funnel, followed by a vas deferens, an atrium and, frequently, a copulatory structure. There may also be a diffuse or compact prostate gland in association with the male duct. In the three species studied, the funnel and vas deferens originate from peritoneal (mesodermal) cells in the posterior septa of the testes segment. The atrium develops from an invagination of the epidermis (ectoderm). The vas deferens and atrium subsequently connect to each other, and a continuous duct from the testes segment to the exterior is formed. The prostate gland originates from large peritoneal cells occurring in a delimited area on the outer surface of the atrium; other small peritoneal cells surrounding the whole atrium give rise to muscle fibres. The spermatheca develops from an invagination of the epidermis, and is thus of ectodermal origin. The morphology and position of the genital ducts have been and are important for the classification of the oligochaetes. However, different parts of the male duct have been named without regard to whether they are homologous or not. One way to establish stronger primary hypotheses of homology is to study the detailed morphology and/or the development of the genital ducts.
The functional-differential equation
y′(t)=Ay(t)
+By(qt)
+Cy′(qt)
+f(t)
Authors: LEHNINGER HARALD , LIU YUNKANG 
Published: July 2002

An initial value problem for the functional differential equationy′(t)
=Ay(t)
+By(qt)
+Cy′(qt)
+f(t), t ≥ t0 > 0where A, B, C are complex matrices,
q∈(0, 1), and f is a vector of continuous functions,
is
considered in this paper. Its solution is represented in terms of
the fundamental solution via the
variation-of-constants formula. For some special cases, the fundamental
solutions are
formulated as piecewise Dirichlet series. The variation-of-constants
formula is used to analysis
the asymptotic behaviour of the solutions of some scalar equations, including
one with variable
coefficients related to coherent states of the q-oscillator
algebra in quantum mechanics.
Historicising ‘1968’
Authors: Mausbach Wilfried 
Published: July 2002

Ingrid Gilcher-Holtey, ed., 1968 – Vom Ereignis zum Gegenstand der Geschichtswissenschaft (Göttingen: Vandenhoeck & Rupprecht, 1998), 307 pp., [euro]36.81, ISBN 3-525-36417-2. Andrew Feenberg and Jim Freedman, When Poetry Ruled the Streets: The French May Events of 1968, with a Foreword by Douglas Kellner (Albany: State University of New York Press, 2001) 192 pp., $18.95, ISBN 0-7914-4966-1. Gerhard Fels, Der Aufruhr der 68er. Zu den geistigen Grundlagen der Studentenbewegung und der RAF (Bonn: Bouvier, 1998) 286 pp., [euro] 23,01, ISBN 3-4160-2816-3. Carole Fink, Philipp Gassert and Detlef Junker, eds., 1968: The World Transformed (New York: Cambridge University Press, 1998), 490 pp., $54.95, ISBN 0-521-64141-1 (hb) $18.95, ISBN 0-521-64637-5 (pb). Ingo Juchler, Die Studentenbewegung in den Vereinigten Staaten und der Bundesrepublik Deutschland der sechziger Jahre: Eine Untersuchung hinsichtlich ihrer Beeinflussung durch Befreiungsbewegungen und – theorien aus der Dritten Welt (Berlin: Duncker & Humblot, 1996), 459 pp., [euro]63.40, ISBN 3-428-08556-6. Michael Kimmel, Studentenbewegungen der 60er Jahre. Frankreich, BRD und USA im Vergleich (Vienna: WUV-Universitätsverlag, 1998), 276 pp., [euro]14.31, ISBN 3-8511-4378-7. Gerd Koenen, Das rote Jahrzehnt: Unsere kleine deutsche Kulturrevolution 1967–1977 (Cologne: Kiepenheuer & Witsch, 2001), 554 pp., [euro]25.51, ISBN 3-4620-2985-1. Wolfgang Kraushaar, 1968 als Mythos, Chiffre und Zäsur (Hamburg: Hamburger Edition, 2000), 370 pp., [euro]24.54, ISBN 3-9309-0859-X. Arthur Marwick, The Sixties: Cultural Revolution in Britain, France, Italy, and the United States, 1958–1974 (Oxford: Oxford University Press, 1998), 903 pp., £25.00, ISBN 0-19-210022-X. Lutz Schulenburg, ed., Das Leben ändern, die Welt verändern. 1968. Dokumente und Berichte (Hamburg: Edition Nautilus, 1998), 471 pp., [euro]20.35, ISBN 3-8940-1289-7.1998 brought yet another outpouring of jubilee literature marking the thirtieth
anniversary of that momentous year 1968. This time, however, there was a noticeable
increase in books with a definite scholarly agenda. Thus, the title Ingrid
Gilcher-Holtey adapted for her edited volume from François Furet may well
capture the gist of a growing feeling: historians are eager to overcome the timeworn
recollections of movement apologists and their adversaries and they are
beginning to subject the 1960s to more objective analysis.
On the Minimum Number of k-Cliques in Graphs with Restricted Independence Number
Authors: NIKIFOROV V. 
Published: July 2002

We investigate the following problem of Erdős:Determine the minimum number of k-cliques in a graph of order n with independence
number [ges ] l.We disprove the original conjecture of Erdős which was stated in 1962 for all but a finite
number of pairs k, l, and give asymptotic estimates for l = 3,
k [ges ] 4, and l = 4, k [ges ] 4.
A skill score based on economic value for probability forecasts
Authors: Wilks D S 
Published: July 2002

AbstractAn approach to evaluating probability forecasts for dichotomous events, based on their economic value over all possible cost/loss ratio decision problems, is proposed. The resulting Value Score (VS) curve shows non‐dimensionalised relative economic value as a function of the cost/loss ratios for different decision‐makers, over their full meaningful range. The VS curve is similar in terms of computational mechanics and graphical display to the Relative Operating Characteristic (ROC) curve, but the ROC curve is shown to be insensitive to either conditional or unconditional biases and thus to reflect potential rather than actual skill. The possibility of collapsing the VS curve into a single scalar score is addressed, and it is shown that the results can depend very strongly on the assumed distribution of cost/loss ratios in the community of forecast users. Copyright © 2001 Royal Meteorological Society
Use of the vertical reflectivity profile for identification of anomalous propagation
Authors: Alberoni P P , Andersson T , Mezzasalma P , Michelson D B , Nanni S 
Published: July 2002

AbstractAnomalous propagation (anaprop), analogous to the upper mirage in the visual wavelengths, is still a major problem in radar meteorology. This phenomenon assumes particular importance in automatic recognition and estimation of rainfall. Anaprop echoes from terrain features such as hills and coasts often give echoes up to 50–60 dBZ, equivalent to heavy rain or hail in severe thunderstorms. Anaprop echoes from sea waves may be comparable in strength to those from moderate precipitation and also form similar patterns. Based on the evidence that the vertical reflectivity profile of precipitation is quite different from the anaprop profile, two methods for anaprop identification are presented. The method proposed by the Servizio Meteorologico Regionale (SMR, Italy) simply uses the operational scan procedure to discriminate between precipitation and anaprop. At the Swedish Meteorological and Hydrological Institute an ‘ad hoc’ scan strategy has been developed in order to obtain much more detail of the lowest reflectivity profile. A number of statistical parameters have been used to achieve a better discrimination between precipitation, land and sea clutter. A number of case studies, representing different echo intensities and patterns, and including a case of anaprop with embedded precipitation, are presented to assess the impact of these methods. Copyright © 2001 Royal Meteorological Society
Potential use of the ECMWF Ensemble Prediction System in cases of extreme weather events
Authors: Petroliagis T , Buizza R , Lanzinger A , Palmer T N 
Published: July 2002

AbstractThe combined use of the European Centre for Medium‐range Weather Forecasts (ECMWF) high‐resolution operational model, at T213 spectral triangular truncation and with 31 vertical levels (T213L31), and the Ensemble Prediction System (EPS), during cases of intense Mediterranean storms, is studied. In particular, it is discussed how EPS products can be used to provide a measure of confidence in the high‐resolution precipitation forecast. Three case studies (two extreme events plus one false‐alarm case) are analysed. The first event took place between 21 and 22 October 1994 over Greece, where heavy rainfall led to local flash‐floods in many areas that cost the loss of 12 lives, and caused significant property damage. The second event occurred in northwest Italy (and some parts of southern France) exactly two weeks later. More than 60 lives were lost and the cost of damage was enormous. For both these cases, the EPS probability values for precipitation occurrence supported the medium‐range T213L31 prediction, which proved to be successful. A third case is also investigated, where the high‐resolution forecast suggested heavy rainfall over northern Italy but was not supported by the EPS. The T213L31 prediction for this case was poor. Finally, the reliability of EPS probability predictions is discussed. It is shown that probability forecasts of low‐level temperature and wind show considerable skill. Reliability statistics of clusters of large‐scale flow show considerable skill as well. Probabilistic precipitation predictions are less skilful, possibly due to the EPS model resolution. Copyright © 1997 Royal Meteorological Society.
Conditioning stochastic properties of daily precipitation on indices of atmospheric circulation
Authors: Kiely Gerard , Albertson John D , Parlange Marc B , Katz Richard W 
Published: July 2002

AbstractTime series of daily precipitation, at Valentia, Ireland, are examined using conditioned chain‐dependent processes. The conditioning is carried out using two different indices of large‐scale atmospheric circulation. The first conditioning index relates to mean monthly sea level pressure (SLP), conditioned as either above or below the historic monthly mean. The second conditioning index is based on the geostrophic wind direction (GWD), conditioned as being inside or outside the historic storm quadrant for the month. For each conditioning index, there are two conditioned daily models and they differ in the parameters that relate to both occurrence and intensity and therefore to changes in the distribution of monthly total precipitation. The results of conditioning the daily precipitation on SLP are compared with conditioning on GWD. The GWD conditioned model gave similar results to the SLP conditioned model for the wetter months, but performed poorly for the summer season. Combining the two SLP conditioned daily models into an induced model, which is a mixture of the two chain dependent processes, produces a variance for monthly total precipitation that is closer to the observed value than the unconditioned chain‐dependent model. Copyright © 1998 Royal Meteorological Society
The accident to a Boeing 737, 7T‐VEE, on approach to Coventry Airport on 21 December 1994
Authors: Pike William S 
Published: July 2002

AbstractMeteorological aspects of a fatal aircraft accident which resulted from collision with a fog‐shrouded 132 Kv suspension transmission tower (an electricity pylon) on approach to Coventry Airport are discussed. Copyright © 1998 Royal Meteorological Society
Transit Peptide Mutations That Impair in Vitro and in Vivo Chloroplast Protein Import Do Not Affect Accumulation of the γ-Subunit of Chloroplast ATPase1
Authors: Kindle Karen L. , Lawrence Susan D. 
Published: July 2002

Abstract
We have begun to take a genetic approach to study chloroplast protein import inChlamydomonas reinhardtii by creating deletions in the transit peptide of the γ-subunit of chloroplast ATPase-coupling factor 1 (CF1-γ, encoded by AtpC) and testing their effects in vivo by transforming the altered genes into anatpC mutant, and in vitro by importing mutant precursors into isolated C. reinhardtii chloroplasts. Deletions that removed 20 or 23 amino acid residues from the center of the transit peptide reduced in vitro import to an undetectable level but did not affect CF1-γ accumulation in vivo. The CF1-γ transit peptide does have an in vivo stroma-targeting function, since chimeric genes in which the stroma-targeting domain of the plastocyanin transit peptide was replaced by the AtpC transit peptide-coding region allowed plastocyanin to accumulate in vivo. To determine whether the transit peptide deletions were impaired in in vivo stroma targeting, mutant and wild-type AtpC transit peptide-coding regions were fused to the bacterial ble gene, which confers bleomycin resistance. Although 25% of the wild-type fusion protein was associated with chloroplasts, proteins with transit peptide deletions remained almost entirely cytosolic. These results suggest that even severely impaired in vivo chloroplast protein import probably does not limit the accumulation of CF1-γ.
Purification and Characterization of Phosphoribulokinase from the Marine Chromophytic Alga Heterosigma carterae1
Authors: Hariharan Tara , Johnson Paula J. , Ann Cattolico Rose 
Published: July 2002

Abstract
In this study we characterized phosphoribulokinase (PRK, EC 2.7.1.19) from the eukaryotic marine chromophyte Heterosigma carterae. Serial column chromatography resulted in approximately 300-fold purification of the enzyme. A polypeptide of 53 kD was identified as PRK by sequencing the amino terminus of the protein. This protein represents one of the largest composite monomers identified to date for any PRK. The native holoenzyme demonstrated by flow performance liquid chromatography a molecular mass of 214 ± 12.6 kD, suggesting a tetrameric structure for this catalyst. Because H. carterae PRK activity was insensitive to NADH but was stimulated by dithiothreitol, it appears that the enzyme may require a thioredoxin/ferredoxin rather than a metabolite mode of regulation. Kinetic analysis of this enzyme demonstrated Michaelis constant values of ribulose-5-phosphate (226 μm) and ATP (208 μm), respectively. In summary, H. carterae PRK is unique with respect to holoenzyme structure and function, and thus may represent an alternative evolutionary pathway in Calvin-cycle kinase development.
Premature Polyadenylation at Multiple Sites within aBacillus thuringiensis Toxin Gene-Coding Region1
Authors: Diehn Scott H. , Chiu Wan-Ling , De Rocher E. Jay , Green Pamela J. 
Published: July 2002

Abstract
Some foreign genes introduced into plants are poorly expressed, even when transcription is controlled by a strong promoter. Perhaps the best examples of this problem are the cry genes ofBacillus thuringiensis (B.t.), which encode the insecticidal proteins commonly referred to asB.t. toxins. As a step toward overcoming such problems most effectively, we sought to elucidate the mechanisms limiting the expression of a typical B.t.-toxin gene,cryIA(c), which accumulates very little mRNA in tobacco (Nicotiana tabacum) cells. Most cell lines transformed with the cryIA(c) B.t.-toxin gene accumulate short, polyadenylated transcripts. The abundance of these transcripts can be increased by treating the cells with cycloheximide, a translation inhibitor that can stabilize many unstable transcripts. Using a series of hybridizations, reverse-transcriptase polymerase chain reactions, and RNase-H-digestion experiments, poly(A+) addition sites were identified in the B.t.-toxin-coding region corresponding to the short transcripts. A fourth polyadenylation site was identified using a chimeric gene. These results demonstrate for the first time to our knowledge that premature polyadenylation can limit the expression of a foreign gene in plants. Moreover, this work emphasizes that further study of the fundamental principles governing polyadenylation in plants will have basic as well as applied significance.
Involvement of Ethylene in Potato Microtuber Dormancy
Authors: Suttle Jeffrey C. 
Published: July 2002

AbstractPotato (Solanum tuberosum L.) single-node explants undergoing in vitro tuberization produced detectable amounts of ethylene throughout tuber development, and the resulting microtubers were completely dormant (endodormant) for at least 12 to 15 weeks. The rate of ethylene production by tuberizing explants was highest during the initial 2 weeks of in vitro culture and declined thereafter. Continuous exposure of developing microtubers to the noncompetitive ethylene antagonist AgNO3 via the culture medium resulted in a dose-dependent increase in precocious sprouting. The effect of AgNO3 on the premature loss of microtuber endodormancy was observed after 3 weeks of culture. Similarly, continuous exposure of developing microtubers to the competitive ethylene antagonist 2,5-norbornadiene (NBD) at concentrations of 2 mL/L (gas phase) or greater also resulted in a dose-dependent increase in premature sprouting. Exogenous ethylene reversed this response and inhibited the precocious sprouting of NBD-treated microtubers. NBD treatment was effective only when it was begun within 7 d of the start of in vitro explant culture. These results indicate that endogenous ethylene is essential for the full expression of potato microtuber endodormancy, and that its involvement may be restricted to the initial period of endodormancy development.
Phenylarsine Oxide Inhibits the Fusicoccin-Induced Activation of Plasma Membrane H+-ATPase
Authors: Olivari Claudio , Albumi Cristina , Pugliarello Maria Chiara , De Michelis Maria Ida 
Published: July 2002

Abstract
To investigate the mechanism by which fusicoccin (FC) induces the activation of the plasma membrane (PM) H+-ATPase, we used phenylarsine oxide (PAO), a known inhibitor of protein tyrosine-phosphatases. PAO was supplied in vivo in the absence or presence of FC to radish (Raphanus sativus L.) seedlings and cultured Arabidopsis cells prior to PM extraction. Treatment with PAO alone caused a slight decrease of PM H+-ATPase activity and, in radish, a decrease of PM-associated 14-3-3 proteins. When supplied prior to FC, PAO drastically inhibited FC-induced activation of PM H+-ATPase, FC binding to the PM, and the FC-induced increase of the amount of 14-3-3 associated with the PM. On the contrary, PAO was completely ineffective on all of the above-mentioned parameters when supplied after FC. The H+-ATPase isolated from PAO-treated Arabidopsis cells maintained the ability to respond to FC if supplied with exogenous, nonphosphorylated 14-3-3 proteins. Altogether, these results are consistent with a model in which the dephosphorylated state of tyrosine residues of a protein(s), such as 14-3-3 protein, is required to permit FC-induced association between the 14-3-3 protein and the PM H+-ATPase.
The Determination Time of the Carpel Whorl Is Differentially Sensitive to Carbohydrate Supply in Pharbitis nil
Authors: Durdan Simon Francis , Herbert Robert James , Rogers Hilary Joan , Francis Dennis 
Published: July 2002

Abstract
A shoot apical meristem is florally determined if, following its removal from an induced plant, it flowers when cultured in non-inductive conditions. Determination times were measured in the short-day plant Pharbitis nil to examine whether floral whorls are determined simultaneously or sequentially. Shoot apices were excised at daily intervals following a 48-h dark-inductive treatment, cultured in non-inductive conditions for 4 weeks in continuous light, and the number of floral organs scored. The culture medium was White's supplemented with sucrose, glucose (Glc), fructose (Fru), or 1:1 Glc:Fru at 2% (w/v), 4% (w/v), or 6% (w/v) or sugar-mannitol combinations of osmotic potentials equivalent to 4% (w/v) or 6% (w/v). The minimum whorl determination time was 1 d for sepals, petals, and stamens regardless of carbon supply. However, for carpels it varied remarkably from 5 d on sucrose, to 2 to 3 d on Fru or Glc:Fru, to 1 d for 2% (w/v) and 6% (w/v) Glc. Therefore, depending on the carbon supply, the carpel whorl was determined at the same time or after the outer whorls. Generally, these effects could not be reproduced on the sugar-mannitol treatments.
Characterization of the Two Saccharopine Dehydrogenase Isozymes of Lysine Catabolism Encoded by the Single Composite AtLKR/SDHLocus of Arabidopsis
Authors: Zhu Xiaohong , Tang Guiliang , Galili Gad 
Published: July 2002

Abstract
Arabidopsis plants possess a composite AtLKR/SDHlocus encoding two different polypeptides involved in lysine catabolism: a bifunctional lysine-ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) enzyme and a monofunctional SDH enzyme. To unravel the physiological significance of these two enzymes, we analyzed their subcellular localization and detailed biochemical properties. Sucrose gradient analysis showed that the two enzymes are localized in the cytosol and therefore may operate at relatively neutral pH values in vivo. Yet while the physiological pH may provide an optimum environment for LKR activity, the pH optima for the activities of both the linked and non-linked SDH enzymes were above pH 9, suggesting that these two enzymes may operate under suboptimal conditions in vivo. The basic biochemical properties of the monofunctional SDH, including its pH optimum as well as the apparent Michaelis constant (K m) values for its substrates saccharopine and nicotinamide adenine dinucleotide at neutral and basic pH values, were similar to those of its SDH counterpart that is linked to LKR. Taken together, our results suggest that production of the monofunctional SDH provides Arabidopsis plants with enhanced levels of SDH activity (maximum initial velocity), rather than with an SDH isozyme with significantly altered kinetic parameters. Excess levels of this enzyme might enable efficient flux of lysine catabolism via the SDH reaction in the unfavorable physiological pH of the cytosol.
Towards a general model for protein–substrate stereoselectivity
Authors: Sundaresan Vidyasankar , Abrol Ravinder 
Published: July 2002

AbstractProtein–substrate interactions in enzymatic, neurological, and immunological systems are typically characterized by a high degree of stereoselectivity towards complex substrates. We propose a novel stereocenter‐recognition (SR) model for stereoselectivity of proteins (or receptors in general) towards substrates that have multiple stereocenters, based on the topology of substrate stereocenters. The model provides the minimum number of substrate locations that need to enter into binding, nonbinding, or repulsive interactions with receptor sites, for stereoselectivity to occur. According to this model, a substrate location may interact with multiple receptor sites, or multiple substrate locations may interact with a single receptor site, but a stereoselective receptor has to offer, in the correct geometry, at least as many interactions as the required minimum number of substrate locations. The SR model predicts that stereoselectivity towards an acyclic substrate with N stereocenters distributed along a single chain requires interactions involving a minimum of N + 2 substrate locations, distributed over all stereocenters in the substrate, such that effectively three locations exist per stereocenter. Thus, enantioselective recognition of molecules with one chiral center requires a protein to interact with a minimum of three substrate locations, while stereoselectivity towards substrates with two or three stereocenters requires interactions with a minimum of four or five substrate locations, respectively, and so on. We demonstrate the general applicability of this model to protein–substrate interactions by interpreting several previous experimental observations.