bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of CfNek, a novel member of the NIMA family of cell cycle regulators, as a polypeptide copurifying with tubulin polyglutamylation activity inCrithidia
Authors: Westermann Stefan , Weber Klaus
Published: November 2002

Post-translational glutamylation of tubulin plays an important role in regulating the interaction between microtubules and associated proteins, but so far the enzymes involved in this process have not been cloned from any cellular source. Using a modified purification scheme that employs a hydroxyapaptite chromatography as the final step we identified a 54 kDa band as the major polypeptide copurifying with tubulin polyglutamylation activity from the trypanosomatid Crithidia fasciculata. Based on peptide sequence information we have cloned the corresponding cDNA and identify Crithidia p54 as a novel member (termed CfNek) of the NIMA family of putative cell cycle regulators. CfNek is a protein of 479 amino acids that contains an unusual protein kinase domain that lacks the glycine-rich loop in subdomain I. The protein also harbours a PEST sequence and a pleckstrin homology domain. The tubulin polyglutamylase preparation displays theβ-casein phosphorylation activity typical for NIMA related kinases. Recombinant His-tagged CfNek expressed in Crithidia localises to the flagellar attachment zone/basal body of the parasite. After purification on a Ni2+-column the recombinant enzyme preparation displays ATP-dependent tubulin polyglutamylation activity as well as casein-phosphorylation activity.
Differentiation plasticity of chondrocytes derived from mouse embryonic stem cells
Authors: Hegert Claudia , Kramer Jan , Hargus Gunnar , Müller Jana , Guan Kaomei , Wobus Anna M. , Müller Peter K. , Rohwedel Jürgen
Published: November 2002

Evidence exists that cells of mesenchymal origin show a differentiation plasticity that depends on their differentiation state. We used in vitro differentiation of embryonic stem cells through embryoid bodies as a model to analyze chondrogenic and osteogenic differentiation because embryonic stem cells recapitulate early embryonic developmental phases during in vitro differentiation. Here, we show that embryonic stem cells differentiate into chondrocytes, which progressively develop into hypertrophic and calcifying cells. At a terminal differentiation stage, cells expressing an osteoblast-like phenotype appeared either by transdifferentiation from hypertrophic chondrocytes or directly from osteoblast precursor cells. Chondrocytes isolated from embryoid bodies initially dedifferentiated in culture but later re-expressed characteristics of mature chondrocytes. The process of redifferentiation was completely inhibited by transforming growth factor β3. In clonal cultures of chondrocytes isolated from embryoid bodies, additional mesenchymal cell types expressing adipogenic properties were observed, which suggests that the subcultured chondrocytes indeed exhibit a certain differentiation plasticity. The clonal analysis confirmed that the chondrogenic cells change their developmental fate at least into the adipogenic lineage. In conclusion, we show that chondrocytic cells are able to transdifferentiate into other mesenchymal cells such as osteogenic and adipogenic cell types. These findings further strengthen the view that standardized selection strategies will be necessary to obtain defined cell populations for therapeutic applications.
Differential acetylation of histones H3 and H4 in paternal and maternal germline chromosomes during development of sciarid flies
Authors: Goday Clara , Ruiz M. Fernanda
Published: November 2002

A classic example of chromosome elimination and genomic imprinting is found in sciarid flies (Diptera. Sciaridae), where whole chromosomes of exclusively paternal origin are discarded from the genome at different developmental stages. Two types of chromosome elimination event occur in the germline. In embryos of both sexes, the extrusion of a single paternal X chromosome occurs in early germ nuclei and in male meiotic cells the whole paternal complement is discarded. In sciarids, early germ nuclei remain undivided for a long time and exhibit a high degree of chromatin compaction,so that chromosomes are cytologically individualized. We investigated chromatin differences between parental chromosomes in Sciara ocellaris and S. coprophila by analyzing histone acetylation modifications in early germ nuclei. We examined germ nuclei from early embryonic stages to premeiotic larval stages, male meiotic cell and early somatic nuclei following fertilization. In early germ cells, only half of the regular chromosome complement is highly acetylated for histones H4 and H3. The chromosomes that are highly acetylated are paternally derived. An exception is the paternal X chromosome that is eliminated from germ nuclei. At later stages preceding the initiation of mitotic gonial divisions, all chromosomes of the germline complement show similar high levels of histone H4/H3 acetylation. In male meiosis, maternal chromosomes are highly acetylated for histones H4 and H3, whereas the entire paternal chromosome set undergoing elimination appears under-acetylated. The results suggest that histone acetylation contributes towards specifying the imprinted behavior of germline chromosomes in sciarids.
Structure of laminin substrate modulates cellular signaling for neuritogenesis
Authors: Freire Elisabete , Gomes Flávia C. A. , Linden Rafael , Neto Vivaldo Moura , Coelho-Sampaio Tatiana
Published: November 2002

Laminin, a major component of basement membranes, can self-assemble in vitro into a typical mesh-like structure, according to a mass-action-driven process. Previously, we showed that pH acidification dramatically increased the efficiency of laminin self-assembly, practically abolishing the necessity for a minimal protein concentration. Here we have characterized the morphologies of laminin matrices produced in either neutral or acidic conditions and compared their capacities to induce neuritogenesis of rat embryonic cortical neurons. Although laminin matrices formed in neutral buffer presented aggregates of heterogeneous morphology, the acidic matrix consisted of a homogeneous hexagonal sheet-like structure. The latter was comparable to the matrix assembled in vivo at the inner limiting membrane of the retina in newborn rats, shown here, and to matrices secreted by cultivated cells, shown elsewhere. The average neurite length of cortical neurons plated on acidic matrices was 244.9 μm, whereas on neutral matrices this value dropped to 104.1 μm. Increased neuritogenesis on the acidic matrix seemed to be associated with a higher degree of neuronal differentiation, since cell proliferation was immediately arrested upon plating, whereas on neutral matrices, the cell number increased six-fold within 24 hours. Investigation of the mechanisms mediating neurite outgrowth on each condition revealed that the extensive neuritogenesis observed on the acidic matrix involved activation of protein kinase A, whereas moderate neuritogenesis on neutral laminin was mediated by activation of protein kinase C and/or myosin light-chain kinase. Explants of cerebral cortex from P2 rats did not grow on the neutral laminin substrate but presented extensive cell migration and neurite outgrowth on the acidic laminin matrix. We propose that laminin can self-assemble independently of cell contact and that the assembling mode differentially modulates neuritogenesis and neuroplasticity.
Lasp-1 binds to non-muscle F-actin in vitro and is localized within multiple sites of dynamic actin assembly in vivo
Authors: Chew Catherine S. , Chen Xunsheng , Parente John A. , Tarrer Shannan , Okamoto Curtis , Qin Hai-Yen
Published: November 2002

Lasp-1 has been identified as a signaling molecule that is phosphorylated upon elevation of [cAMP]i in pancreas, intestine and gastric mucosa and is selectively expressed in cells within epithelial tissues. In the gastric parietal cell, cAMP-dependent phosphorylation induces the partial translocation of lasp-1 to the apically directed F-actin-rich canalicular membrane, which is the site of active HCl secretion. Lasp-1 is an unusual modular protein that contains an N-terminal LIM domain, a C-terminal SH3 domain and two internal nebulin repeats. Domain-based analyses have recently categorized this protein as an epithelial representative of the nebulin family, which also includes the actin binding, muscle-specific proteins,nebulin, nebulette and N-RAP.

In this study, we show that lasp-1 binds to non-muscle filamentous (F)actin in vitro in a phosphorylation-dependent manner. In addition, we provide evidence that lasp-1 is concentrated within focal complexes as well as in the leading edges of lamellipodia and the tips of filopodia in non-transformed gastric fibroblasts. In actin pull-down assays, the apparent Kd of bacterially expressed his-tagged lasp-1 binding to F-actin was 2 μM with a saturation stoichiometry of ∼1:7. Phosphorylation of recombinant lasp-1 with recombinant PKA increased the Kd and decreased the Bmax for lasp-1 binding to F-actin. Microsequencing and site-directed mutagenesis localized the major in vivo and in vitro PKA-dependent phosphorylation sites in rabbit lasp-1 to S99 and S146. BLAST searches confirmed that both sites are conserved in human and chicken homologues. Transfection of lasp-1 cDNA encoding for alanine substitutions at S99 and S146, into parietal cells appeared to suppress the cAMP-dependent translocation of lasp-1 to the intracellular canalicular region. In gastric fibroblasts, exposure to the protein kinase C activator, PMA, was correlated with the translocation of lasp-1 into newly formed F-actin-rich lamellipodial extensions and nascent focal complexes. Since lasp-1 does not appear to be phosphorylated by PKC,these data suggest that other mechanisms in addition to cAMP-dependent phosphorylation can mediate the translocation of lasp-1 to regions of dynamic actin turnover. The localization of lasp-1 to these subcellular regions under a range of experimental conditions and the phosphorylation-dependent regulation of this protein in F-actin rich epithelial cells suggests an integral and possibly cell-specific role in modulating cytoskeletal/membrane-based cellular activities.
Genome-wide gene expression profiling inArabidopsis thalianareveals new targets of abscisic acid and largely impaired gene regulation in theabi1-1mutant
Authors: Hoth Stefan , Morgante Michele , Sanchez Juan-Pablo , Hanafey Michael K. , Tingey Scott V. , Chua Nam-Hai
Published: November 2002

The phytohormone abscisic acid (ABA) plays important regulatory roles in many plant developmental processes including seed dormancy, germination,growth, and stomatal movements. These physiological responses to ABA are in large part brought about by changes in gene expression. To study genome-wide ABA-responsive gene expression we applied massively parallel signature sequencing (MPSS) to samples from Arabidopsis thaliana wildtype (WT)and abi1-1 mutant seedlings. We identified 1354 genes that are either up- or downregulated following ABA treatment of WT seedlings. Among these ABA-responsive genes, many encode signal transduction components. In addition,we identified novel ABA-responsive gene families including those encoding ribosomal proteins and proteins involved in regulated proteolysis. In the ABA-insensitive mutant abi1-1, ABA regulation of about 84.5% and 6.9%of the identified genes was impaired or strongly diminished, respectively;however, 8.6% of the genes remained appropriately regulated. Compared to other methods of gene expression analysis, the high sensitivity and specificity of MPSS allowed us to identify a large number of ABA-responsive genes in WT Arabidopsis thaliana. The database given in our supplementary materialprovides researchers with the opportunity to rapidly assess whether genes of interest may be regulated by ABA. Regulation of the majority of the genes by ABA was impaired in the ABA-insensitive mutant abi1-1. However, a subset of genes continued to be appropriately regulated by ABA, which suggests the presence of at least two ABA signaling pathways, only one of which is blocked in abi1-1.
Subcellular targeting of metabolic enzymes to titin in heart muscle may be mediated by DRAL/FHL-2
Authors: Lange Stephan , Auerbach Daniel , McLoughlin Patricia , Perriard Evelyne , Schäfer Beat W. , Perriard Jean-Claude , Ehler Elisabeth
Published: November 2002

During sarcomere contraction skeletal and cardiac muscle cells consume large amounts of energy. To satisfy this demand, metabolic enzymes are associated with distinct regions of the sarcomeres in the I-band and in the M-band, where they help to maintain high local concentrations of ATP. To date,the mechanism by which metabolic enzymes are coupled to the sarcomere has not been elucidated. Here, we show that the four and a half LIM-only protein DRAL/FHL-2 mediates targeting of the metabolic enzymes creatine kinase,adenylate kinase and phosphofructokinase by interaction with the elastic filament protein titin in cardiomyocytes. Using yeast two-hybrid assays,colocalisation experiments, co-immunoprecipitation and protein pull-down assays, we show that DRAL/FHL-2 is bound to two distinct sites on titin. One binding site is situated in the N2B region, a cardiac-specific insertion in the I-band part of titin, and the other is located in the is2 region of M-band titin. We also show that DRAL/FHL-2 binds to the metabolic enzymes creatine kinase, adenylate kinase and phosphofructokinase and might target these enzymes to the N2B and is2 regions in titin. We propose that DRAL/FHL-2 acts as a specific adaptor protein to couple metabolic enzymes to sites of high energy consumption in the cardiac sarcomere.
Trafficking of lysosomal cathepsin B—green fluorescent protein to the surface of thyroid epithelial cells involves the endosomal/lysosomal compartment
Authors: Linke Martin , Herzog Volker , Brix Klaudia
Published: November 2002

Cathepsin B, a lysosomal cysteine proteinase, is involved in limited proteolysis of thyroglobulin with thyroxine liberation at the apical surface of thyroid epithelial cells. To analyze the trafficking of lysosomal enzymes to extracellular locations of thyroid epithelial cells, we have expressed a chimeric protein consisting of rat cathepsin B and green fluorescent protein. Heterologous expression in CHO cells validated the integrity of the structural motifs of the chimeric protein for targeting to endocytic compartments. Homologous expression, colocalization and transport experiments with rat thyroid epithelial cell lines FRT or FRTL-5 demonstrated the correct sorting of the chimeric protein into the lumen of the endoplasmic reticulum, and its subsequent transport via the Golgi apparatus and the trans-Golgi network to endosomes and lysosomes. In addition, the chimeras were secreted as active enzymes from FRTL-5 cells in a thyroid-stimulating-hormone-dependent manner. Immunoprecipitation experiments after pulse-chase radiolabeling showed that secreted chimeras lacked the propeptide of cathepsin B. Thus, the results suggest that cathepsin B is first transported to endosomes/lysosomes from where its matured form is retrieved before being secreted, supporting the view that endosome/lysosome-derived cathepsin B contributes to the potential of extracellular proteolysis in the thyroid.
Spatial regulation of the guanine nucleotide exchange factor Lte1 inSaccharomyces cerevisiae
Authors: Jensen Sanne , Geymonat Marco , Johnson Anthony L. , Segal Marisa , Johnston Leland H.
Published: November 2002

In budding yeast, activation of the small Ras-like GTPase Tem1 triggers exit from mitosis and cytokinesis. Tem1 is regulated by Bub2/Bfa1, a two-component GTPase-activating protein (GAP), and by Lte1, a putative guanine nucleotide exchange factor. Lte1 is confined to the bud cortex, and its spatial separation from Tem1 at the spindle pole body (SPB) is important to prevent untimely exit from mitosis. The pathways contributing to Lte1 asymmetry have not been elucidated. Here we show that establishment of Lte1 at the cortex occurs by an actin-independent mechanism, which requires activation of Cdc28/Cln kinase at START and Cdc42, a key regulator of cell polarity and cytoskeletal organisation. This defines a novel role for Cdc42 in late mitotic events. In turn, dissociation of Lte1 from the cortex in telophase depends on activation of the Cdc14 phosphatase. Ectopic expression of Cdc14 at metaphase results in premature dephosphorylation of Lte1 coincident with its release from the cortex. In vitro phosphatase assays confirm that Lte1 is a direct substrate for Cdc14. Our results suggest that the asymmetry in Lte1 localisation is imposed by Cdc28-dependent phosphorylation.

Finally, we report a mutational analysis undertaken to investigate intrinsic Lte1 determinants for localisation. Our data suggest that an intrameric interaction between the N-and C-terminal regions of Lte1 is important for cortex association.
Interaction of periplakin and envoplakin with intermediate filaments
Authors: Karashima Tadashi , Watt Fiona M.
Published: November 2002

Periplakin is a component of desmosomes and the epidermal cornified envelope. Its N-terminal domain interacts with the plasma membrane; it heterodimerises with envoplakin via its rod domain; and its C-terminus interacts with intermediate filaments. Periplakin has the shortest C-terminus of the plakin family, comprising only the linker domain found in all conventional plakins. By transient transfection of COS7 cells and primary human epidermal keratinocytes with deletion mutants of the periplakin C-terminus we mapped sequences required for intermediate filament interaction to two regions of the linker motif that are most highly conserved amongst the plakins. The results were confirmed by overlay assays of the binding of in vitro translated periplakin constructs to keratins and vimentin. We found that envoplakin and periplakin could still associate with each other when parts of their rod domains were deleted and, surprisingly, that removal of the entire rod domain did not completely inhibit their interaction. Co-transfection of constructs containing the C-termini of envoplakin and periplakin suggested that the periplakin C-terminus may stabilise the interaction of the envoplakin C-terminus with intermediate filaments. We conclude that the periplakin C-terminus plays an important role in linking periplakin and envoplakin to intermediate filaments.
Plasma membrane localization of the Yck2p yeast casein kinase 1 isoform requires the C-terminal extension and secretory pathway function
Authors: Babu Praveen , Bryan Joshua D. , Panek Heather R. , Jordan Solomon L. , Forbrich Brynn M. , Kelley Shannon C. , Colvin Richard T. , Robinson Lucy C.
Published: November 2002

The S. cerevisiae Yck2 protein is a plasma membrane-associated member of the casein kinase 1 protein kinase family that, with its homolog Yck1p, is required for bud morphogenesis, cytokinesis, endocytosis and other cellular processes. Membrane localization of Yckp is critical for its function, since soluble mutants do not provide sufficient biological activity to sustain normal growth. Yck2p has neither a predicted signal sequence nor obvious transmembrane domain to achieve its plasma membrane localization, but has a C-terminal -Cys-Cys sequence that is likely to be palmitoylated. We demonstrate here that Yck2p is targeted through association with vesicular intermediates of the classical secretory pathway. Yck2p lacking C-terminal Cys residues fails to associate with any membrane, whereas substitution of these residues with a farnesyl transferase signal sequence allows sec-dependent plasma membrane targeting and biological function,suggesting that modification is required for interaction with early secretory membranes but that targeting does not require a particular modification. Deletion analysis within the 185 residue C-terminus indicates that the final 28 residues are critical for membrane association, and additional sequences just upstream are required for proper plasma membrane targeting.
Novel function of Chat in controlling cell adhesion via Cas-Crk-C3G-pathway-mediated Rap1 activation
Authors: Sakakibara Akira , Ohba Yusuke , Kurokawa Kazuo , Matsuda Michiyuki , Hattori Seisuke
Published: November 2002

Chat (Cas/HEF1-associated signal transducer) is a novel signaling molecule with an N-terminal SH2 domain and C-terminal Cas/HEF1 association domain that is implicated in the regulation of cell adhesion. The Cas/HEF1 association domain also shows sequence similarity with guanine nucleotide exchange factors for Ras family small GTPases. In this study, we found significant activation of Rap1 in Chat-overexpressing cells. Myr-Chat, a membrane-targeted form of Chat,activated Rap1 more efficiently. Interestingly, Chat and Cas synergistically activated Rap1. Certain Cas, Crk or C3G mutants suppressed Rap1 activation by Chat. We also confirmed the ternary complex formation consisting of Chat, Cas and Crk. Thus, it is likely that Chat-induced Rap1 activation was mediated by upregulation of the Cas-Crk-C3G signaling pathway rather than direct guanine nucleotide exchange factor activity of Chat. We further demonstrated that Myr-Chat expression induced cell periphery spreading and cell shape branching and that this activity also depended on the Cas-Crk-C3G pathway and Rap1 activity. Moreover, expression of Myr-Chat enhanced integrin-mediated cell adhesion. Taken together we propose a novel role for the Chat-Cas complex in controlling cell adhesion via the activation of Rap1.
Apoptosis-inducing factor (AIF): key to the conserved caspase-independent pathways of cell death?
Authors: Candé Céline , Cecconi Francesco , Dessen Philippe , Kroemer Guido
Published: November 2002

Numerous pro-apoptotic signal transducing molecules act on mitochondria and provoke the permeabilization of the outer mitochondrial membrane, thereby triggering the release of potentially toxic mitochondrial proteins. One of these proteins, apoptosis-inducing factor (AIF), is a phylogenetically old flavoprotein which, in healthy cells, is confined to the mitochondrial intermembrane space. Upon lethal signaling, AIF translocates, via the cytosol,to the nucleus where it binds to DNA and provokes caspase-independent chromatin condensation. The crystal structures of both human and mouse AIF have been determined, and the fine mechanisms accounting for its oxidoreductase activity and its electrostatic interaction with double-stranded DNA have been elucidated. Importantly, the apoptogenic and oxidoreductase functions of AIF can be dissociated. Thus, mutations that abolish the AIF-DNA interaction suppress AIF-induced chromatin condensation, yet have no effect on the NADH oxidase activity. Recent studies suggest AIF to be a major factor determining caspase-independent neuronal death, emphasizing the central role of mitochondria in the control of physiological and pathological cell demise.
Towards quantifying droplet clustering in clouds
Authors: Shaw R. A. , Kostinski A. B. , Larsen M. L.
Published: November 2002

Droplet positions in atmospheric clouds are random but possibly correlated on some scales. This ‘clustering’ must be quantified in order to account for it in theories of cloud evolution and radiative transfer. Tools as varied as droplet concentration power spectrum, Fishing test, and fractal correlation analysis have been used to describe the small‐scale nature of clouds, and it has been difficult to compare conclusions systematically. Here we show, by using the correlation‐fluctuation theorem and the Wiener–Khinchin theorem, that all of these measures can be related to the pair‐correlation function. It is argued that the pair‐correlation function is ideal for quantifying droplet clustering because it contains no scale memory and because of its quantitative link to the Poisson process. Copyright © 2002 Royal Meteorological Society
Extratropical low‐frequency variability as a low‐dimensional problem. II: Stationarity and stability of large‐scale equilibria
Authors: D'andrea Fabio
Published: November 2002

Stationarity and stability properties of large‐scale persistent anomalies in the northern hemisphere are addressed. The low‐order model developed in Part I is used for this purpose. It was obtained as the projection of a three‐level quasi‐geostrophic system on the ten leading empirical orthogonal functions. Three global quasi‐ stationary states are identified, which represent the Arctic high and the positive and negative phases of the main teleconnections (Pacific North American and North Atlantic oscillation). The quasi‐stationary solutions have only a partial correspondence to the weather regimes found in Part I. Stability analysis shows a growing mode that describes an oscillation between the two phases of the teleconnections. The negative teleconnection state is also shown to be much more stable than the other two. Possible decay mechanisms are also discussed. Copyright © 2002 Royal Meteorological Society
Intercomparison and evaluation of cumulus parametrizations under summertime midlatitude continental conditions
Authors: Xie Shaocheng , Xu Kuan‐Man , Cederwall Richard T. , Bechtold Peter , Genio Anthony D. Del , Klein Stephen A. , Cripe Douglas G. , Ghan Steven J. , Gregory David , Iacobellis Sam F. , Krueger Steven K. , Lohmann Ulrike , Petch Jon C. , Randall David A. , Rotstayn Leon D. , Somerville Richard C. J. , Sud Yogesh C. , Salzen Knut Von , Walker Gregory K. , Wolf Audrey , Yio J. John , Zhang Guang Jun , Zhang Minghua
Published: November 2002

This study reports the Single‐Column Model (SCM) part of the Atmospheric Radiation Measurement (ARM)/the Global Energy and Water Cycle Experiment (GEWEX) Cloud System Study (GCSS) joint SCM and Cloud‐Resolving Model (CRM) Case 3 intercomparison study, with a focus on evaluation of cumulus parametrizations used in SCMs. Fifteen SCMs are evaluated under summertime midlatitude continental conditions using data collected at the ARM Southern Great Plains site during the summer 1997 Intensive Observing Period. Results from ten CRMs are also used to diagnose problems in the SCMs.

It is shown that most SCMs can generally capture well the convective events that were well‐developed within the SCM domain, while most of them have difficulties in simulating the occurrence of those convective events that only occurred within a small part of the domain. All models significantly underestimate the surface stratiform precipitation. A third of them produce large errors in surface precipitation and thermodynamic structures. Deficiencies in convective triggering mechanisms are thought to be one of the major reasons. Using a triggering mechanism that is based on the vertical integral of parcel buoyant energy without additional appropriate constraints results in overactive convection, which in turn leads to large systematic warm/dry biases in the troposphere. It is also shown that a non‐penetrative convection scheme can underestimate the depth of instability for midlatitude convection, which leads to large systematic cold/moist biases in the troposphere.

SCMs agree well quantitatively with CRMs in the updraught mass fluxes, while most models significantly underestimate the downdraught mass fluxes. Neglect of mesoscale updraught and downdraught mass fluxes in the SCMs contributes considerably to the discrepancies between the SCMs and the CRMs. In addition, uncertainties in the diagnosed mass fluxes in the CRMs and deficiencies with cumulus parametrizations are not negligible.

Similar results are obtained in the sensitivity tests when different forcing approaches are used. Finally, sensitivity tests from an SCM indicate that its simulations can be greatly improved when its triggering mechanism and closure assumption are improved. © Royal Meteorological Society, 2002. J. C. Petch's contribution is Crown copyright.
Maslov's method for stationary hydrostatic mountain waves
Authors: Broutman Dave , Rottman James W. , Eckermann Stephen D.
Published: November 2002

The ray solution for stationary hydrostatic mountain waves has a singularity along the vertical axis directly over the mountain. We use Maslov's method to improve the ray prediction. The ray solution is determined in the wave‐number domain and is then mapped by inverse Fourier transform to give a spatial description of the wave field that approximates the linear solution over the mountain and elsewhere. We develop Maslov's method for a medium with a height‐dependent mean wind and mean buoyancy, and we compare it with the traditional transform method and with the results of a numerical simulation. Copyright © 2002 Royal Meteorological Society
Multi‐scale description of a Sahelian synoptic weather system representative of the West African monsoon
Authors: Redelsperger J.‐L. , Diongue A. , Diedhiou A. , Ceron J.‐P. , Diop M. , Gueremy J.‐F. , Lafore J.‐P.
Published: November 2002

A reference case of a Sahelian weather system observed during the Hydrological Atmospheric Pilot Experiment, HAPEX‐SAHEL, in August 1992, is described from a seasonal viewpoint as well as from synoptic and convective system viewpoints. It is shown that the case‐study is representative of the climatology at all these scales and presents many interacting scales and physical processes. At intraseasonal scale, the monsoon onset is characterized by an abrupt shift of precipitation together with a latitudinal migration of the African easterly jet (AEJ) and convection. At the month and day scales, the convective activity occurs in an apparent zonal break of the tropical easterly jet. The month of August 1992 exhibits intense synoptic activity. The vorticity field is characterized by northerly (dry) and southerly (wet) components located at 850 hPa on each side of the AEJ. Their intraseasonal modulation on a period of 20 to 40 days leads to active and break phases of the synoptic activity. Around 21 August, the 700 hPa vorticity field features the propagation of a typical easterly wave with a westward propagation of a cyclonic circulation followed by an anticyclonic circulation. Convective activity occurs mainly ahead of the 700 hPa vorticity maximum with the formation of a squall line on Aïr mountains propagating south‐westward at 15 m s−1. The convective system propagates about twice as fast as the vortex core, in contrast with the convection in the European Centre for Medium‐Range Weather Forecasts re‐analysis which stays in phase with the vorticity. The squall line corresponds to the largest contributor to the systems passing in August 1992 over the HAPEX‐SAHEL region; its environmental conditions and its effects on the atmosphere including the surface parameters are presented. Copyright © 2002 Royal Meteorological Society
Response of the atmosphere–ocean mixed‐layer system to anomalous ocean heat‐flux convergence
Authors: Sutton R. , Mathieu P.‐P.
Published: November 2002

We investigate the role of the extratropical oceans in climate variability. Rather than following the traditional approach of studying the atmospheric response to prescribed sea‐surface‐temperature (SST) anomalies, we focus on the role of anomalous ocean heat transport. We employ an atmosphere model coupled to a fixed‐depth (‘slab’) ocean mixed‐layer model, forced by a field of ocean heat‐flux convergence (OHFC). We study the response of this coupled atmosphere–ocean mixed‐layer system to an idealized OHFC anomaly.

We find that the OHFC forcing is mainly balanced by anomalous surface latent‐heat flux, i.e. enhanced evaporation. Notably, the anomalous SST is not co‐located with the forcing, nor with the anomalous air–sea flux, nor with the anomalous diabatic heating. Contrary to conventional wisdom, in our experiment the influence of the extratropical ocean on the atmosphere is not manifest primarily in an SST signature. The anomalous diabatic heating is associated with a downstream surface low‐pressure anomaly, in line with the simple theory of the steady response to extratropical heating. Transient‐eddy anomalies play only a minor role. The principal SST anomaly appears to be a passive response to this anomalous atmospheric flow.

Our results suggest that the traditional narrow focus on SST as the key variable involved in ocean–atmosphere interaction may offer only a limited, perhaps even misleading, guide to the influence of the extratropical oceans on climate variability. Copyright © 2002 Royal Meteorological Society
The cold Arctic winter 1995/96 as observed by GOME and HALOE: Tropospheric wave activity and chemical ozone loss
Authors: Weber M. , Eichmann K.‐U. , Wittrock F. , Bramstedt K. , Hild L. , Richter A. , Burrows J. P. , Üller R. M
Published: November 2002

The Global Ozone Monitoring Experiment aboard the European Remote Sensing Satellite ERS‐2 was the only satellite instrument measuring total ozone on a near‐global scale during the extremely cold Arctic winter 1995/96. Extremely low total ozone was observed within the Arctic vortex during February and March. The lowest value in this winter was 178 DU (Dobson units) over Greenland on 19 February, which was about 160 DU below the February Arctic vortex mean of total ozone. Although severe chemical ozone destruction occurred in late winter 1995/96, the extremely low values in total ozone observed after the middle of February were, in all cases, related to mini‐hole events, where large horizontal divergent transport of ozone from the lower‐stratospheric layer above a high tropopause rapidly reduced the total column in a localized region. The observed total‐ozone minima were located near the vortex edge and in the region of minimum lower‐stratospheric temperatures that were, in selected cases, sufficiently low for the formation of polar stratospheric ice clouds (PSC type II) below 188 K at the isentropic level of 475 K. Coincident ozone profile observations in early March from the Halogen Occultation Experiment on the Upper Atmosphere Research Satellite indicate that the strong chemical ozone loss was mainly confined to the polar vortex region, and that the extremely low total‐ozone values below 250 DU were mainly caused by short‐term reversible dynamical reductions superimposed upon chemical ozone loss occurring on longer timescales. Enhanced OClO and chlorine activation, due to strong tropospheric wave activity associated with an ozone mini‐hole event, was only observed in early March following a stratospheric temperature drop below the ice frost point. In general, however, the observation of very low total ozone in mini‐hole events does not necessarily point to significant additional chemical depletion. Copyright © 2002 Royal Meteorological Society
The interaction between model resolution, observation resolution and observation density in data assimilation: A one‐dimensional study
Authors: Liu Z.‐Q. , Rabier F.
Published: November 2002

In this paper, the optimal configurations of model resolution, observation resolution and observation density are investigated in a simple one‐dimensional framework. In this context, the representativeness error is formalized and estimated before being used in the analysis‐error formulation. Some optimal and suboptimal assimilation‐schemes, differing from different approximations of observation‐error covariance and observation operator, are compared. The optimal observation‐extent is determined as a function of model resolution. Increasing the observation density is usually beneficial, except for suboptimal schemes similar to the ones used in operational practice. The impact of thinning the observations with correlated error is also studied from a suboptimal viewpoint. Copyright © 2002 Royal Meteorological Society
Synthesis and study of new polyamides with side oxadiazole rings
Authors: Bruma M. , Hamciuc E. , Schulz B. , Kopnick T. , Kaminorz Y. , Robison J.
Published: November 2002

A series of six new aromatic polyamides with side oxadiazole rings has been synthesized by polycondensation reaction of aromatic diamines containing pendent substituted oxadiazole groups with a silicon‐containing diacid chloride [namely, bis(p‐chlorocarbonyl‐phenylene)diphenylsilane] or with a fluorine‐containing diacid chloride [namely, hexafluoroisopropylidene‐bis(p‐benzoyl chloride)]. All polymers were easily soluble in amidic solvents, such as N‐methylpyrrolidinone and dimethylformamide, and gave thin transparent films by casting such solutions. Very thin coatings were deposited onto silicon wafers and exhibited smooth, pinhole‐free surfaces in atomic force microscopy investigations. The polymers showed high thermal stability, with decomposition temperature >400°C. Some of them did exhibit a glass transition, in the range 152–276°C, with a reasonable interval between glass transition and decomposition. Four of these polymers showed blue photoluminescence, in the range 460–480 nm, which makes them promising candidates for future use as high‐performance materials in the construction of light‐emitting devices. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 714–721, 2003
Parenting and the Harry Potter stories: a social care perspective
Authors: Seden Janet
Published: November 2002

This paper analyses the capacities of the parents in the Harry Potter stories, written by J. K. Rowling, from a social care perspective. It argues that there is a synergy between what the social sciences have discovered about ‘good enough parenting’ and the insights that can be gathered from entering the imaginative world of literature. This is illustrated by a discussion of the qualities of the parents and parent substitutes in the four books published between 1997 and 2000. It concludes that fictional experiences of childhood create empathy in the reader and enable us to confront the need for imagination as parents and practitioners, while the social sciences keep knowledge grounded and evidenced. Copyright © 2002 John Wiley & Sons, Ltd.
The PALS parenting support programme: lessons learned from the evaluation of processes and outcomes
Authors: Zeedyk M. Suzanne , Werritty Irene , Riach Christine
Published: November 2002

Although there has recently been a rise in parenting support programmes within the UK, only a minority of these programmes have benefited from evaluation of either outcomes or processes. This paper describes the development of the PALS programme (Parents Altogether Lending Support), reporting both on its effectiveness in improving parents' interactions with their children and on the lessons that were learned about embedding such a programme within the local community. Over the 18‐month period of the programme, a total of 17 courses were run, with 75 parents and carers (primarily mothers) participating in the programme overall. Evaluation results indicated that participants enjoyed the course and found it beneficial, particularly in terms of altering their own actions in specific ways that were able to promote better behaviour on the part of their children. Participants also valued the opportunity to share their experiences with other parents. The key lesson identified in regard to the development of parenting programmes concerned the need for the community to feel a sense of ownership for the initiative. Copyright © 2002 John Wiley & Sons, Ltd.
M‐sequence‐based M‐ary/SS/CDMA system using blocked viterbi decoding and accurate SNIR measurement techniques for high‐bit‐rate wireless communication systems
Authors: Ito Takumi , Sampei Seiichi , Morinaga Norihiko
Published: November 2002

This paper discusses the application of M‐ary/SS (M‐ary/Spread Spectrum) to DS/CDMA (Direct Sequence/Code Division Multiple Access) system. M‐ary/SS system can realize a high‐bit‐rate transmission while maintaining a high processing gain. On the other hand, the system requires the same number of correlators as the number of candidate spreading codes. In this study, the orthogonal code based on M‐sequence is used as the spreading sequence, in order to simplify the correlator configuration. In addition, an algorithm is proposed to realize the error‐correcting code and the transmit power control, which are necessary in DS/CDMA system. As a result of analysis by computer simulation, it is shown that the proposed system has an excellent transmission performance. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 80–91, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10012
1.28 Tbit/s—70‐km OTDM femtosecond‐pulse transmission using third‐ and fourth‐order simultaneous dispersion compensation with a phase modulator
Authors: Yamamoto Takashi , Tamura Kohichi R. , Nakazawa Masataka
Published: November 2002

By means of the higher‐order dispersion compensation technique using a phase modulator, a 70‐km transmission experiment with 1.28 Tbit/s OTDM (Optical Time Domain Multiplexing) signals has been successfully conducted for the first time. The details are reported in this paper. The 1.28 Tbit/s signal is obtained by 64‐fold multiplexing of 10 Gbit/s signals with additional polarization multiplexing. For the signal pulse with a pulse width of 380 fs prior to transmission, a linear chirp is imparted and then a cosine phase modulation with an appropriate amplitude and the timing is set in such a way that the imparted chirp is opposite to the chirps caused by the third‐ and fourth‐order dispersion in the transmission path. In this way, the waveform distortion of the signal due to the third‐ and fourth‐order dispersion can be suppressed simultaneously. The pulse widening of the signal after transmission over 70 km is only 20 fs. Hence, an error rate of less than 1 × 10−9can be realized over the entire channel (10 Gbit/s–128 channels after multiplexing separation). © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 68–79, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10028
Communication quality control scheme by using priority control mechanism for ethernet‐based wireless LANs
Authors: Saitoh Kazuyoshi , Inoue Yasuhiko , Iizuka Masataka , Morikura Masahiro
Published: November 2002

A method that realizes CoS (Class of Service) control in Ethernet is communication quality control based on the user priority specified by IEEE 802.1D Annex H. This paper presents a result of investigation of CoS control scheme in IEEE 802.11 system, which is Ethernet wireless LAN standardized by IEEE 802 Committee. An evaluation is also tried by computer simulation, and it is found that the bounded delay time and the bandwidth guarantee are realized, providing the best effort with higher priority in the contention control. It is also shown that the proposed scheme can be used as protection against the user who sends/receives a large amount of data, constraining the bandwidth. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 53–67, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10029
Bi‐soliton pulse in a dispersion‐managed optical transmission system and its application
Authors: Nonaka Yasumichi , Inoue Takashi , Maruta Akihiro
Published: November 2002

In this paper, the mutual interaction of adjacent pulses is studied as a cause for degradation of the transmission quality of a dispersion‐managed (DM) soliton. It is shown that the variation of the pulse spacing due to the mutual interaction between two DM solitons can be made extremely small by appropriately selecting the incident pulse spacing and the transmission line parameters. Next, the averaging method is applied to two DM solitons in the parameter region in which the effect of this mutual interaction becomes extremely small. It is shown that there exists a bi‐soliton as a steady solution with two main lobes. Its nature is discussed in detail. Further, a novel transmission line coding scheme using this bi‐soliton is worked out and a method to reduce the interpulse mutual interaction is proposed. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 44–52, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10035
Computation of GPS continuity with consideration of progress of time
Authors: Sakai Takeyasu , Koremura Kazunobu
Published: November 2002

The international civil aviation organization (ICAO) has defined the international standard for the global navigation satellite system (GNSS) based on GPS for aviation use. Navigation systems for aviation must ensure not only the specific positioning accuracy but also the required reliability performance. Continuity is one of the measures of system reliability, and is defined as the probability that the system operates without nonscheduled interruptions over a certain period of time. We have already proposed a method of computing the continuity of GPS for the approach and landing flight phase. However, the method cannot be applied to flight phases such as enroute or terminal airspace because of the longer periods for such phases, for example 1 hour, over which the continuity requirements are defined. This paper describes a method of computing continuity with consideration of the progress of time, taking into account the movement of the aircraft relative to navigation satellites. Some computation examples are also presented. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 26–34, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10044
Traffic characteristics of Go‐back‐N ARQ scheme with selective repeat in intra‐block
Authors: Maeda Akiko , Sugimachi Nobuyuki , Hayashida Yukuo , Fujii Shumji
Published: November 2002

This paper discusses the traffic characteristics of the Go‐back‐N (GBN)_SR scheme, in which the receiver returns the acknowledge signal blockwise and selective repeat is performed within the retransmission block. First the strict expression for the throughput and the strict expression for the average transmission delay of the blockwise bulk arrival model are derived. Then, the throughput of the GBN_SR scheme and the average transmission delay of the blockwise bulk arrival model are examined by numerical calculation. The average transmission delay of the packetwise bulk arrival model is investigated by simulation. It is shown that the throughput is improved with increasing block size, and that the average transmission delay can be minimized by using the optimal block size, depending on the average packet error rate and the block arrival rate. It is also shown for the packetwise bulk arrival model that there exists a block size which minimizes the average transmission delay, and that the minimum average transmission delay is smaller than in the blockwise bulk arrival model. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 9–16, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ ecja.10052
The influence of gender‐stereotyped perfumes on leadership attribution
Authors: Sczesny Sabine , Stahlberg Dagmar
Published: November 2002

The classification of perfumes as ‘women's’ and ‘men's’ fragrances is based on certain gender stereotypes. In two experiments, female and male participants were asked to assume the role of a manager. In Experiment 1, they read an application for the position of a junior manager written by a male or female job applicant. Application papers were prepared with a typically masculine perfume, a typically feminine perfume or no perfume at all (control group). In Experiment 2, participants conducted a job interview with a female or male applicant (a confederate) who had applied the respective perfume or no perfume. Persons with a typically masculine perfume were ‘employed’ with a higher degree of certainty compared to persons with a typically feminine perfume. Copyright © 2002 John Wiley & Sons, Ltd.