bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationship between chaperone activity and oligomeric size of recombinant human αA‐ and αB‐crystallin: A tryptic digestion study
Authors: Saha S. , Das K. P.
Published: July 2004

α‐Crystallin, the major eye lens protein, exists as a large oligomer of two subunits, αA‐ and αB‐crystallin. The individual subunits assemble into the oligomer in vitro. It is generally believed that oligomerization is pre‐requisite for chaperone function, although there is no hard data available on this subject. We therefore undertook a study using limited tryptic digestion as a tool for examining the relationship between oligomeric size and chaperone activity of recombinant αA‐ and αB‐crystallin. We showed that tryptic digested fragments of both αA‐ and αB‐crystallin much smaller than the original subunits retain considerable chaperone activity. Our results indicate that chaperone activity depends more on the sequence of the reduced peptide than on its oligomeric size. The results also suggest that the presence of the α‐crystallin domain and hydrophobic clefts on the protein surface, which correlate poorly with oligomeric size, are important for chaperone function. Proteins 2004. © 2004 Wiley‐Liss, Inc.
A portable allosteric mechanism
Authors: Gryczynski Urszula , Schleif Robert
Published: July 2004

The allosteric mechanism by which the gene expression regulatory protein AraC regulates its DNA‐binding activity is shown to be portable by grafting it to β‐galactosidase, generating an arabinose‐regulated β‐galactosidase. A portion of the α‐peptide sequence that complements the activity of α‐acceptor β‐galactosidase was inserted into a nonessential region of the regulatory peptidyl arm of AraC protein. Arabinose, which regulates the position of the arm in AraC protein now regulates the availability of the α‐peptide to α‐acceptor β‐galactosidase, thereby modulating its activity in response to arabinose. Proteins 2004. © 2004 Wiley‐Liss, Inc.
FRP strengthening of concrete structures: new inventions and applications
Authors: Täljsten Björn
Published: July 2004

The advantages of FRP strengthening have been shown time and again during the last decade. All over the world several thousand structures retrofitted with FRPs exist. There are various reasons why the retrofit is needed, but since buildings and civil structures usually have a very long life, it is not uncommon that the demands on the structure change with time. The structures may have to carry larger loads at a later date or fulfil new standards. In extreme cases, a structure may need repair, owing to an accident, or to errors made during the design or construction phase, such that the structure needs to be strengthened before it can be used. Over the past decade, the issue of deteriorating infrastructure has become a topic of critical importance in Europe, and to an equal extent in North America and Japan.

The deterioration of bridge decks, superstructure elements and columns can be traced to reasons ranging from ageing and environmentally induced degradation, to poor initial construction and lack of maintenance. Added to the problems of deterioration are issues related to the need for higher load ratings and increased numbers of lanes to accommodate the ever‐increasing traffic flow on major arteries.

As a result, a significant portion of our infrastructure is currently either structurally or functionally deficient. Beyond the costs and visible consequences associated with continuous retrofit and repair of such structural components are the real consequences related to losses in production and overall economic issues related to time and resources caused by delays and detours. As we move into the twenty‐first century, the renewal of our lifelines becomes critical. Here, FRP strengthening may be a tool in the overall toolbox to be used to overcome some of the problems related to repair and strengthening of structures.

In this paper a short historical background to plate bonding is presented. The paper focuses on the possibility of improving the existing technology and how drawbacks can be overcome.
Base sequence dependence of charge transport via short DNA bridges
Authors: Matulewski J. , Baranovskii S. D. , Thomas P.
Published: July 2004

Charge transfer in a donor – short bridge – acceptor system is studied within a simple model of a DNA molecule. A difference in transfer rates via two bridges containing similar bases though with opposite sequences is demonstrated. The result calls for experimental verification. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of molecular formulas and structural regularities of low molecular weight fulvic acids by size‐exclusion chromatography with electrospray ionization quadrupole time‐of‐flight mass spectrometry
Authors: These Anja , Winkler Marcus , Thomas Christoph , Reemtsma Thorsten
Published: July 2004

Size‐exclusion chromatography was coupled to a quadrupole time‐of‐flight mass spectrometer using electrospray ionization in the negative ion mode to analyze Suwannee River fulvic acid. About 220 exact masses of low molecular weight fulvic acids (FAs) were measured in the range from m/z 190 to 350, and molecular formulas could be deduced for all these molecular masses. All molecular formulas can be described by the superimposition of three homologous series in the FA mixture: (a) a series of hydrogen homologs constituted of five to six members for a given number of carbons and oxygens; (b) a series of alkyl chain homologs with stepwise addition of one methylene group; and (c) isobaric compounds that differ by the formal replacement of an oxygen atom by a methane group. Product ion spectra of the FA species reflect the repeated parallel losses of carbon dioxide and water. The minimum number of carboxylate groups and the maximum number of hydroxy moieties could be determined from the product ion spectra. Furthermore, it was obvious that the structural differences between homologs in the three series are located in the carbon backbone of the FA rather than in its extremities that are expelled as neutral fragments. These structural regularities reduce the complexity of FA mixtures to a certain set of yet unknown basic structures. Copyright © 2004 John Wiley & Sons, Ltd.
Formation of molecular radical cations of aliphatic tripeptides from their complexes with CuII(12‐crown‐4)
Authors: Chu Ivan K. , Siu S. O. , Lam Corey N. W. , Chan Jenny C. Y. , Rodriquez Christopher F.
Published: July 2004

Molecular radical cations have proven to be difficult to generate from aliphatic peptides under electrospray ionization mass spectrometry (ESI‐MS) conditions. For a family of small aliphatic peptides GGX, where XG, A, P, I, L and V, these cations have been generated by electrospraying a mixture of Cu.2+, 12‐crown‐4 and GGX in methanol/water. GGX.+ is readily formed from the collision‐induced dissociation (CID) of [CuII(12‐crown‐4)(GGX)].2+. The formation of these aliphatic peptide radical ions from these complexes, in cases where it is not possible from the corresponding complexes involving a series of amine ligands instead of 12‐crown‐4, is likely due to the second ionization energy of the [CuI(12‐crown‐4)(GGX)]+ complex being higher than that of the corresponding [CuI(amine)(GGX)]+ complex. Using these 12‐crown‐4 complexes, GGI can be differentiated from the isomeric GGL by comparing the CID spectra of their [a3+H].+ ions. Copyright © 2004 John Wiley & Sons, Ltd.
Structural analysis of naphthoquinone protein adducts with liquid chromatography/tandem mass spectrometry and the scoring algorithm for spectral analysis (SALSA)
Authors: Zhang Fagen , Bartels Michael J.
Published: July 2004

The relative reactivities of various naphthoquinone isomers (1,4‐, 1,2‐ and 2‐methyl‐1,4‐naphthoquinone) to two test proteins, apomyoglobin and human hemoglobin, were evaluated via liquid chromatography/electrospray ionization mass spectrometry (LC/ESI‐MS). The structural characterization of the resulting adducts was also obtained by LC/ESI‐MS analysis of the intact proteins. The reactive sites of apomyoglobin and human hemoglobin with 1,4‐naphthoquinone and 1,2‐naphthoquinone were also identified through characterization of adducted tryptic peptides by use of high‐pressure liquid chromatography/electrospray ionization with tandem mass spectrometry (HPLC/ESI‐MS/MS), TurboSEQUEST®, and the scoring algorithm for spectral analysis (SALSA). Four adducted peptides, which were formed by nucleophilic addition of a lysine amino acid residue to 1,4‐naphthoquinone, were also identified, as was an adducted peptide from incubation of 1,2‐naphthoquinone with apomyoglobin. In the case of incubation of human hemoglobin with the two naphthoquinones, two adducted peptides were identified from the N‐terminal valine modification of the alpha and beta chains of human hemoglobin. The adducted protein formation may imply that naphthalene produces its in vivo toxicity through 1,2‐ and 1,4‐naphthoquinone metabolites reacting with biomolecular proteins. Copyright © 2004 John Wiley & Sons, Ltd.
Fragmentation study of diastereoisomeric 2‐methyltetrols, oxidation products of isoprene, as their trimethylsilyl ethers, using gas chromatography/ion trap mass spectrometry
Authors: Wang Wu , Vas Gyorgy , Dommisse Roger , Loones Kristof , Claeys Magda
Published: July 2004

The diastereoisomeric 2‐methyltetrols, 2‐methylthreitol and 2‐methylerythritol, were recently reported as major secondary aerosol components in natural forest aerosols and proposed as molecular markers for the photooxidation of isoprene. In this study, we examine the complex electron and methane chemical ionization behaviors of their trimethylsilyl ethers. In order to gain insight into their fragmentation behaviors, threitol and erythritol were studied as model compounds, and deuterium labeling of the trimethylsilyl groups and ion trap MS2 experiments were performed. Copyright © 2004 John Wiley & Sons, Ltd.
Thin‐layer chromatography combined with diode laser desorption/atmospheric pressure chemical ionization mass spectrometry
Authors: Peng Song , Ahlmann Norman , Kunze Kerstin , Nigge Walter , Edler Michael , Hoffmann Thorsten , Franzke Joachim
Published: July 2004

The desorption of an analyte by a continuous wave diode laser from a porous surface of a thin‐layer plate covered with a graphite suspension is presented. The thermally desorbed analyte molecules are ionized in the gas phase by a corona discharge at atmospheric pressure. Therefore, both essential processes—the desorption and the ionization of analyte molecules, which are often performed in one step—are separated. The target preparation is easy and fast since no additional extraction process is required. The mass spectrometric background signal was mostly limited to the low mass range showing no interference with typical compounds of interest. In this study, the calmative and antihypertensive drug reserpine was chosen as model analyte, which is often used for specification of mass spectrometers. No fragmentation was observed because of efficient collisional cooling under atmospheric pressure. The influence of diode laser power and the composition of the graphite suspension were investigated, and a primary optimization was performed. Copyright © 2004 John Wiley & Sons, Ltd.
Determination of halofuginone in eggs by liquid chromatography/tandem mass spectrometry after cleanup with immunoaffinity chromatography
Authors: Mortier L. , Daeseleire E. , Huet A.‐C. , Delahaut P. , Van Peteghem C.
Published: July 2004

A sensitive and very selective high‐performance liquid chromatography/tandem mass spectrometric (LC/MS/MS) method for the detection of halofuginone in whole egg has been developed. After deproteinisation with acetonitrile and evaporation of the organic solvent, halofuginone was further isolated by applying immunoaffinity chromatography. The concentrated eluent was injected into the LC/MS/MS system on a C18 column. The precursor ion ([M+H]+) produced by positive electrospray ionisation was selected for fragmentation with argon. Validation parameters such as recovery, linearity and repeatability, decision limit (CCα) and detection capability (CCβ) were determined. Copyright © 2004 John Wiley & Sons, Ltd.
A parametric insensitive H2control design approach
Authors: Chevrel Philippe , Yagoubi Mohamed
Published: July 2004

H2and H∞control design methodologies are known to be efficient to deal with multivariable control problems. However, most of them do not take explicitly the parametric uncertainties into account. This paper proposes a low parametric sensitivity H2control design method as an alternative toµ‐synthesis or robust H2control design. In addition to the standard H2criterion, the H2norm of the parametric sensitivity function is introduced in order to improve the robustness of the resulting controller. Unfortunately, this problem is a difficult one. Its equivalence to structured feedback H2control problem will be shown. The underlying BMI will be solved by making use of an iterative LMI procedure. Two examples will illustrate the interest of the approach. Copyright © 2004 John Wiley & Sons, Ltd.
Stability analysis and control of a class of differential‐algebraic nonlinear systems
Authors: Coutinho D. F. , Bazanella A. S. , Trofino A. , e Silva A. S.
Published: July 2004

A new methodology based on the linear matrix inequality (LMI) framework is presented for the computation of polynomial Lyapunov functions for differential–algebraic nonlinear systems. The method is applied for estimating the domain of attraction of equilibria and also as a control design tool to increase the damping of the system. Numerical examples are used to demonstrate the approach. The results show the potential of the proposed approach as a tool for analysis and control design. Copyright © 2004 John Wiley & Sons, Ltd.
Robust stability of neutral systems: a Lyapunov‐Krasovskii constructive approach
Authors: Rodrìguez S.A. , Kharitonov V. , Dion J.‐M. , Dugard L.
Published: July 2004

In this paper, robust stability of uncertain linear neutral systems is analysed via a Lyapunov–Krasovskii constructive approach. This paper is the first attempt to compute the Lyapunov–Krasovskii functional for a given time derivative functional w(·) for the class of linear neutral type time delay systems. Copyright © 2004 John Wiley & Sons, Ltd.
Design of low‐order controllers satisfying sensitivity constraints for unstructured uncertain plants
Authors: Yaniv O.
Published: July 2004

This paper presents a simple analytically based algorithm for the design of reduced‐order controllers satisfying frequency‐dependent sensitivity specifications for SISO plants having unstructured uncertainty. The uncertainties can be additive as well as multiplicative, and can take the form of circles, polygons or sectors located around a nominal plant. Moreover, the circle radius and polygon and sector sizes may depend on the frequency. The proposed method is applicable to both continuous and discrete designs. Copyright © 2004 John Wiley & Sons, Ltd.
Drought refuges affect algal recolonization in intermittent streams
Authors: Robson Belinda J. , Matthews Ty G.
Published: July 2004

Drought refuges enable the biota of intermittent streams to survive dry periods, but their roles in sustaining algal assemblage structure and productivity are not known. This study determined the importance of two types of drought refuge (dry biofilm, permanent pools) for benthic algal regrowth in four intermittent streams in the Grampians National Park, Victoria, Australia. Dry biofilm was removed by scrubbing randomly chosen stones from two dry riffles in each of two streams with permanent pools and two streams without permanent pools. Algae were sampled from scrubbed and control stones at one, six and sixteen weeks after flow resumed. Removal of dry algal biofilm resulted in lower algal densities on stones from both stream types, and scrubbed stones had similar densities of algae after one week, regardless of the presence or absence of permanent pools. Algal density on stones exposed to both refuge types was more than an order of magnitude higher than the density on stones exposed to either one or neither refuge. The effects of biofilm removal on algal density were still apparent after six weeks of flow and assemblage composition differed between streams with and without permanent pools. Dry biofilm was an important drought refuge for algae in both stream types, but epilithic algal density in streams with permanent pools developed more rapidly than streams that were completely dry over summer. Loss of permanent pools from intermittent streams due to water abstraction may substantially reduce algal productivity after flow resumes, which may limit the supply of autochthonous carbon. Copyright © 2004 John Wiley & Sons, Ltd.
A research C# compiler
Authors: Hanson David R. , Proebsting Todd A.
Published: July 2004

C# is the new flagship language in the Microsoft .NET platform. C# is an attractive vehicle for language design research not only because it shares many characteristics with Java, the current language of choice for such research, but also because it is likely to see wide use. Language research needs a large investment in infrastructure, even for relatively small studies. This paper describes a new C# compiler designed specifically to provide that infrastructure. The overall design is deceptively simple. The parser is generated automatically from a possibly ambiguous grammar, accepts C# source, perhaps with new features, and produces an abstract syntax tree, or AST. Subsequent phases—dubbed visitors—traverse the AST, perhaps modifying it, annotating it or emitting output, and pass it along to the next visitor. Visitors are specified entirely at compilation time and are loaded dynamically as needed. There is no fixed set of visitors, and visitors are completely unconstrained. Some visitors perform traditional compilation phases, but the more interesting ones do code analysis, emit non‐traditional data such as XML, and display data structures for debugging. Indeed, most usage to date has been for tools, not for language design experiments. Such experiments use source‐to‐source transformations or extend existing visitors to handle new language features. These approaches are illustrated by adding a statement that switches on a type instead of a value, which can be implemented in a few hundred lines. The compiler also exemplifies the value of dynamic loading and of type reflection. Copyright © 2004 John Wiley & Sons, Ltd.
Dynamic reconfiguration of CPU and WebSphere on IBM pSeries servers
Authors: Jann Joefon , Dubey Niteesh , Burugula R. S. , Pattnaik Pratap
Published: July 2004

This paper studies the effects that dynamic reconfiguration (DR) has on a WebSphere workload while CPUs are dynamically added to and removed from the underlying AIX instance. DR is a new technology available in AIX 5.2. This study shows that the resource allocations for a complex and function‐rich middleware system such as WebSphere can be efficiently and dynamically managed by the DR technology, without WebSphere having to explicitly accommodate for the DR features of the operating system. Copyright © 2004 John Wiley & Sons, Ltd.
Biegedrillknicken von Trägern mit einfach‐symmetrischen Profilen
Authors: Vayas Ioannis
Published: July 2004

Ein wesentliches Problem beim Nachweis von Trägern unter Momentenbeanspruchung stellt die Ermittlung des elastischen kritischen Moments für Biegedrillknicken dar. Im vorliegenden Beitrag werden einfache Formeln zur Ermittlung des kritischen Moments von gabelgelagerten Trägern angegeben. Die Formeln decken viele praktische Anwendungsfälle ab. Die Herleitung erfolgt durch Anwendung der Energiemethode und Lösung nach dem Ritz'schen Verfahren. Für die Verdrehungen werden eingliedrige Ansätze gemacht. Die Ergebnisse werden mit genaueren Lösungen unter Anwendung mehrgliedriger Ansätze verglichen. Der Vergleich zeigt, daß für die üblichen Abmessungen die Genaugkeit innerhalb akzeptabler Grenzen bleibt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Der Berstdruck eines zylindrischen Stahlsilos unter Explosionsinnendruckbeanspruchung
Authors: Wasicek Manfred , Fischer Franz Dieter , Sabirov Ilshat , Kolednik Otmar
Published: July 2004

Beim Füllen und Entleeren eines Silos kann es durch die Staubentwicklung des Lagerguts und das Vorhandensein einer Zündquelle zu einer Staubexplosion kommen, welche durch ihre Heftigkeit ein großes Risiko für die Anlage darstellt.

Dieser Beitrag beschäftigt sich mit der druckstoßfesten Ausführung von Silos, welche dem zu erwartenden Explosionsdruck mit bleibenden Verformungen widersteht. Das Grenztragverhalten der einzelnen Schalenanteile des Silos, wie Zylinder, Kegel, Torus und Kugelkalotte, wird mit Hilfe der Plastizitätstheorie und dem Kriterium nach Considère bestimmt. Das Tragverhalten der Schalenübergänge wird mittels einer nichtlinearen Berechnung mit dem Finite‐Element‐Programm ABAQUS untersucht. Weiter werden die plastischen Grenzdrücke aufgrund von fehlerbehafteten Schweißnähten (Kerben und Risse) an den Schalenverbindungen mittels der Schädigungs‐ und Bruchmechanik bestimmt, wobei die Materialkennwerte aus den durchgeführten Versuchen verwendet wurden. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Einfluß der Auflagerpositionen auf die 1. Eigenfrequenz beim Euler‐Bernoulli‐Balken
Authors: Homann Stefan , Keye Stefan
Published: July 2004

Es wird ein Verfahren vorgestellt, mit dem sich für einen Euler‐Bernoulli‐ Balken konstanter Länge die 1. Eigenkreisfrequenz als Funktion des Abstands der Auflager in analytisch geschlossener Form beschreiben läßt. Basierend auf der Annahme, daß die potentielle Energie der Eigenschwingungsform vom Abstand der Auflager unabhängig ist, wird die Eigenkreisfrequenz mit Hilfe des Rayleigh‐Quotienten näherungsweise bestimmt. Zur Abschätzung der Güte der Näherung wird ein Vergleich mit einer numerischen Lösung vorgenommen. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fertigung und Montage des Messeturms in Rostock
Authors: Klimke Herbert , Stephan Sören , Essrich Reiner
Published: July 2004

Dieser Beitrag beschreibt die Realisierung eines Tensegrity‐Turms, der auf einem dreieckigen Grundriß aufgebaut und bei dem jedes Segment um 30° verdreht ist (Twistelement). Die Realisierung erfordert die Einhaltung ungewöhnlich kleiner Fertigungstoleranzen, insbesondere bei den Seilen, und ein konsistentes Konzept für den Toleranzausgleich. Ein Hauptproblem der Realisierung ist das Vorspannen der Seile, das durch gleichzeitiges Verschieben der drei Fußpunkte jedes Elements mit Hilfe von 100‐t‐Pressen gelöst wurde. Der Turm wurde aus den Twistelementen zunächst in zwei Teilen zusammengebaut und dann das obere Teil mit einem 170‐t‐Mobilkran auf das untere Teil gehoben. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beulanalyse wellenförmiger Schalen veränderlicher Dicke
Authors: Shigematsu Tsunemi , Ohga Mitao , Hara Takashi
Published: July 2004

In der vorliegenden Arbeit wird die Stabilität für zwei Arten wellenförmiger Schalen mit dünnwandigen Querschnitten veränderlicher Dicke untersucht. Dabei besitzen die Krümmungen der kontinuierlichen Schalen ungleiche Richtungen. Bei der Herleitung der Õbertragungsmatrix werden der negative Krümmungsradius und der Õbertragungswinkel für wellenförmige Schalen eingeführt. Die Ergebnisse werden als Beulwerte und Beulformen mitgeteilt. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zur Effizienz von Queraussteifungen und unteren Verbänden bei breiten Straßendeckbrücken
Authors: Unterweger Harald , Kaim Peter
Published: July 2004

Der Beitrag behandelt verschiedene Variantenstudien zum Tragsystem einer mehrfeldrigen Straßendeckbrücke in Verbundbauweise mit Stützweiten von etwa 70 m im Zuge der notwendigen Verstärkung einer bestehenden Brücke. Ursprünglich handelt es sich um eine Autobahnbrücke mit zwei getrennten Tragwerken mit jeweils zwei Hauptträgern, die einen einzelligen Kastenquerschnitt bilden. Neben dieser Ausbildung wird eine Verbindung beider Tragwerke mit zusätzlichen Querverbänden und eine Ergänzung zu einem dreizelligen Kastenquerschnitt untersucht. Zu Vergleichszwecken erfolgt eine Berechnung für zwei isolierte Tragwerke mit offenem Querschnitt sowie deren Ergänzung mit durchlaufenden Querverbänden zu einem offenen Trägerrost. Weiterhin wird die Variation von Steifigkeit und Anzahl der Verbände für alle Systeme untersucht. Die Ergebnisse werden in Form von vertikalen Durchbiegungen sowie Einflußlinien und Beanspruchungen in repräsentativen Hauptträger‐ und Verbandsquerschnitten vergleichend dargestellt. Daraus ist die Effizienz der Queraussteifungen und unteren Verbände direkt ablesbar. Damit lassen sich für die sinnvolle Verstärkung von Autobahnbrücken mit zwei getrennten Tragwerken (offener Querschnitt oder Kastenquerschnitt) sowie auch für die sinnvollste Systemwahl bei Neubauten im Falle großer Fahrbahnbreiten, generelle Hinweise ableiten. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Biegedrillknickmomente und Eigenformen von Biegeträgern unter Berücksichtigung der Drehbettung
Authors: Kindmann Rolf , Muszkiewicz Reiner
Published: July 2004

In DIN 18800 [1] und im EC 3 wird das ideale Biegedrillknickmoment als Bezugsgröße für den Tragsicherheitsnachweis biegedrillknickgefährdeter Träger verwendet. Aus wirtschaftlichen Gründen ist es dabei vorteilhaft, die stabilisierende Wirkung angrenzender Bauteile zu berücksichtigen. In diesem Beitrag wird über die Ermittlung von MKi unter Berücksichtigung einer Drehbettung berichtet. Darüber hinaus wird gezeigt, welchen Funktionsverlauf die zugehörigen Eigenformen haben, da sie für Nachweise unter Ansatz von geometrischen Ersatzimperfektionen benötigt werden. Als Alternative zu Berechnungen mit Hilfe von EDV‐Programmen werden für ausgewählte baustatische Systeme Näherungsformeln angegeben, die die Ermittlung von MKi mittels Handrechnung ermöglichen. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatial hierarchical approach in community ecology: a way beyond high context‐dependency and low predictability in local phenomena
Authors: Noda Takashi
Published: July 2004

Patterns and functioning of communities, which are determined by a set of processes operating at a large variety of spatial and temporal scales, exhibit quite high context‐dependency and low predictability at the fine spatial scales at which recent studies have concentrated. More attention to broader scale and across‐scale phenomena may be useful to search for general patterns and rules in communities. In this context, it is effective to incorporate hierarchical spatial scale explicitly into the experimental and sampling design of field studies, an approach referred to here as thespatial hierarchical approach, focusing on a particular assemblage in which biological interaction and species life history are well known. The spatial hierarchical approach can provide insight into the effects of scale in operating processes and answers to a number of important questions in community ecology such as: (1) detection of patterns and processes in spatiotemporal variability in communities, including how to explain the partitioning of pattern information of species diversity at a broad scale into finer scales, and the pattern of spatial variability of community properties at the finest spatial scale; (2) evaluation of changes in patterns observed in macroecology at finer scales; (3) testing of models explaining the coexistence of competing species; and (4) detection of latitudinal patterns in spatiotemporal variability in communities and their causal processes.
Latitudinal gradient of species diversity: multi‐scale variability in rocky intertidal sessile assemblages along the Northwestern Pacific coast
Authors: Okuda Takehiro , Noda Takashi , Yamamoto Tomoko , Ito Norihiko , Nakaoka Masahiro
Published: July 2004

This study examined the latitudinal gradient of species diversity of rocky intertidal sessile assemblages on the slopes of rocks along the Northwestern Pacific coast of Japan, located between 31°N and 43°N, by explicitly incorporating an hierarchical spatial scale into the monitoring design. The specific questions were to examine: (1) whether there is a latitudinal gradient of regional diversity, (2) how spatial components of the regional diversity (local diversity and turnover diversity) vary with latitude depending on spatial scale, and (3) whether the latitudinal gradient differs between different measures of species diversity, i.e. species richness and Simpson's diversity index. We measured coverage and the presence or absence of all sessile organisms in a total of 150 census plots established at five shores in each of six regions. The results showed that there were clear latitudinal gradients in regional species richness and in species turnover among shores. However, these patterns were not reflected in smaller‐scale local species richness. For Simpson's diversity index, there was no evidence of latitudinal clines either in regional diversity or in spatial components. These results suggest that relative abundance of common species does not vary along latitude, while the number of rare species increases with decreasing latitude.
Identification of ubiquitin‐interacting proteins in purified polyglutamine aggregates
Authors: Doi Hiroshi , Mitsui Kenichi , Kurosawa Masaru , Machida Yoko , Kuroiwa Yoshiyuki , Nukina Nobuyuki
Published: July 2004

Nuclear aggregates of enhanced green fluorescent protein and nuclear localization signal‐fused truncated N‐terminal huntingtin containing 150 repeats of glutamine residue were purified from ecdysine‐inducible mutant neuro2A cell line by sequential extraction of nuclear soluble proteins. To analyze the aggregate‐interacting proteins, we subjected the nuclear aggregates to high performance liquid chromatography–mass spectrometry analysis. The resulting data revealed the presence of three new putative aggregate‐interacting proteins: ubiquilin 1, ubiquilin 2 and Tollip. These proteins also associated with neuronal intranuclear inclusions in a mouse model of Huntington disease (HD). These aggregate‐interacting proteins contain ubiquitin‐interacting motifs, suggesting that they are recruited to the aggregates where they may lose their normal function.
Accumulation of the common mitochondrial DNA deletion induced by ionizing radiation
Authors: Prithivirajsingh Sheela , Story Michael D , Bergh Sherry A , Geara Fady B , Kian Ang K , Ismail Sheikh M , Stevens Craig W , Buchholz Thomas A , Brock William A
Published: July 2004

Point mutations and deletions in mitochondrial DNA (mtDNA) accumulate as a result of oxidative stress, including ionizing radiation. As a result, dysfunctional mitochondria suffer from a decline in oxidative phosphorylation and increased release of superoxides and other reactive oxygen species (ROS). Through this mechanism, mitochondria have been implicated in a host of degenerative diseases. Associated with this type of damage, and serving as a marker of total mtDNA mutations and deletions, the accumulation of a specific 4977‐bp deletion, known as the common deletion (Δ‐mtDNA4977), takes place. The Δ‐mtDNA4977 has been reported to increase with age and during the progression of mitochondrial degeneration. The purpose of this study was to investigate whether ionizing radiation induces the formation of the common deletion in a variety of human cell lines and to determine if it is associated with cellular radiosensitivity. Cell lines used included eight normal human skin fibroblast lines, a radiosensitive non‐transformed and an SV40 transformed ataxia telangiectasia (AT) homozygous fibroblast line, a Kearns Sayre Syndrome (KSS) line known to contain mitochondrial deletions, and five human tumor lines. The Δ‐mtDNA4977 was assessed by polymerase chain reaction (PCR). Significant levels of Δ‐mtDNA4977 accumulated 72 h after irradiation doses of 2, 5, 10 or 20 Gy in all of the normal lines with lower response in tumor cell lines, but the absolute amounts of the induced deletion were variable. There was no consistent dose–response relationship. SV40 transformed and non‐transformed AT cell lines both showed significant induction of the deletion. However, the five tumor cell lines showed only a modest induction of the deletion, including the one line that was deficient in DNA damage repair. No relationship was found between sensitivity to radiation‐induced deletions and sensitivity to cell killing by radiation.
Seed persistence of oilseed rape (Brassica napus): variation in transgenic and conventionally bred cultivars
Authors: GRUBER S. , PEKRUN C. , CLAUPEIN W.
Published: July 2004

Seeds of oilseed rape (Brassica napus L.) can persist in the soil over several years by becoming secondarily dormant and can then germinate to create volunteer plants in following crops. As well as agricultural impacts caused by volunteers, gene dispersal in time – particularly from genetically modified cultivars – can be another undesirable consequence. Conventionally bred and transgenic seeds were tested in 2001 and 2002 in laboratory experiments, and in a field experiment, by burying seeds in the soil to determine the variation in dormancy and persistence capacity.

In the conventional group of cultivars tested in the laboratory, the level of dormancy was 13–76% in 2001, and 3–76% with an extended group in 2002. The transgenic group of cultivars was 1–31% dormant. In the burial experiments the number of viable seeds recovered in the conventionally bred cultivars ranged from 34–90% in 2001, and 7–68% in 2002. In the same studies the transgenic cultivars developed persistence levels from 12–79% in 2001, and 46–67% in 2002. Since dormancy levels of conventionally bred cultivars from 2 harvest years in the laboratory tests correlated significantly (r=0·71), it appears that there is a genetic background to secondary dormancy. There was also a significant correlation (r=0·61 in 2001 and 0·80 in 2002) between the results from laboratory and burial experiments. This indicates that the laboratory approach can simulate the situation in the field. Ageing over 6 months decreased the capacity for seed persistence to about a fifth of the level shown when freshly harvested. As a consequence of ageing and environmental impacts on persistence, only seeds from the same location and harvest year should be used for testing genetic variability. The high genetic variability among currently available rape seed cultivars gives breeding strategies a good chance of ideotyping low persistence genotypes and minimizing the risk of gene dispersal in time.
The effect of bulk density on bite dimensions of cattle grazing microswards in the field
Authors: CASEY I. A. , LAIDLAW A. S. , BRERETON A. J. , McGILLOWAY D. A. , WATSON S.
Published: July 2004

The effect of sward bulk density on bite mass and bite dimensions was examined in two experiments using oesphageally fisulated cows to graze microswards under field conditions. In Experiment 1 microswards of uniform sward height were hand thinned to create differences in sward bulk density. In Experiment 2 plots were sown with monocultures of a range of ryegrass cultivars selected on the basis of their contrasting sward structures to provide a range of sward bulk densities and grazed down in two consecutive strata. Both methods were successful in providing a range of microswards of different sward bulk densities. In Experiment 1 bite mass increased significantly as sward bulk density increased. In Experiment 2 bites taken from the first stratum did not differ significantly in mass due to bites being deeper in swards with low bulk density, compensating for the lower bite bulk density. However, mass of bites taken mainly from the second stratum were lower in some swards due to lower bite bulk density which was related to tiller density rather than sward bulk density. The results emphasize the importance of sward bulk density in determining bite mass and dimensions, especially for the first stratum, and of tiller density in the bulk density of bites in the lower stratum in sward depletion, the latter requiring to be studied further.
Herbage production and animal performance on perennial ryegrass/white clover dairy pastures under alternative spring grazing managements
Authors: DA SILVA S. C. , HODGSON J. , MATTHEW C. , MATTHEWS P. N. P. , HOLMES C. W.
Published: July 2004

Spring grazing managements which allowed some early inflorescence development, followed by hard grazing in order to remove the reproductive stems (designated ‘late control’), were compared with a conventional close grazing strategy (‘early control’) in three paddock-scale complete randomized block studies with dairy cows grazing perennial ryegrass/white clover pastures during consecutive years (1990–1993) in Palmerston North, New Zealand. Experiment 1 was designed to evaluate the timing of late control, Expt 2 to investigate the most suitable intensity of control, and Expt 3 tested different practical approaches to carrying out the late control management.

Late control generated an average herbage production increase of 24% (750 kg DM/ha) in October and November (spring) and 22% (950 kg DM/ha) from January to April (summer–autumn) compared with the conventional management. The increase in herbage accumulation during spring was a consequence of greater perennial ryegrass reproductive development. Increased summer–autumn herbage accumulation after late control management was attributed to enhanced tillering activity and accumulation of perennial ryegrass. Effects on white clover production were inconsistent. Experiment 3 compared the effects of two practical late control strategies, involving either a short period of rapid rotational grazing or a simulation of increased stocking rate normally associated with forage conservation, on the milk production and forage intake of groups of cows in self-contained farmlet systems. During the control period, the reproductive state of the sward caused a small decrease in herbage digestibility. However, the extra herbage produced subsequently did not differ in digestibility from that produced on the conventionally managed sward and resulted in an increase of around 11·5% in total milk solids yield (fat, protein and lactose) per cow, particularly towards the end of the season (March and April).

The late control spring grazing management strategy is a viable option for dairy farmers. It should coincide with the time of anthesis of ryegrass plants (late November–early December), and is more effectively achieved when forage conservation practices are used to augment grazing pressure in the grazed area of the farm.
Effect of rotation system and N fertilizer on barley and vetch grown in various crop combinations and cycle lengths
Authors: PAPASTYLIANOU I.
Published: July 2004

Under rainfed Mediterranean conditions the dominant crops are cereals and legumes, with the most common crops being barley (Hordeum vulgare) and vetch (Vicia sativa). These two species are grown in rotation, where the cycle length depends on the productivity and the value of the products in the market. In order to study the productivity of cereals and legumes growing in various rotation combinations, an experiment was conducted during the 1982–2000 period, at Athalassa. The experimental site had a calcareous soil and is located in the central plane of Cyprus. The average rainfall is 250 mm per year. The rotation treatments tested were: (a) continuous barley, (b) continuous vetch, (c) vetch–barley, (d) vetch–barley–barley, (e) vetch–vetch–barley–barley and (f) vetch–vetch–vetch–barley–barley. Barley plots were equally divided to accommodate two rates of N fertilizer (0 and 60 kg N/ha) which were applied at seeding. Production of both vetch and barley was lower in monocultures than when the two species were grown in rotation. Vetch yield was similar in all rotations, irrespective of the position in the cycle. Productivity of barley was increased by nitrogen application only when grown as a second barley after vetch. However, in years with low productivity due to the rainfall amount and distribution, barley did not respond to nitrogen application. The first crop of barley after vetch gave maximum production without any nitrogen fertilizer application. Nitrogen fertilizer had a decreasing effect on the size and weight of barley grains. These results enable the farmers to select any of the rotation systems studied, based on the economics of the two species, without risking productivity. Nitrogen fertilizer should be applied only to the second crop after vetch in years with high rainfall.
Optimum sowing dates for okra (Abelmoschus esculentus) in monoculture and mixture with cassava (Manihot esculenta) during the rainy season in the south-west of Nigeria
Authors: OLASANTAN F. O. , BELLO N. J.
Published: July 2004

Experiments to evaluate the optimum sowing date for okra (Abelmoschus esculentus) sown in monoculture or in mixed stands with cassava (Manihot esculenta) were sited on free-draining sandy loam soils in southwestern Nigeria. Okra was sown at the end of July, in mid-August and early September as a late-season crop in 1999 and at the end of May, in early June and at the end of June as an early-season crop in 2000. It was sown at seed rates sufficient to achieve final population densities of 33000 and 40000 plants/ha in late-season crops (1999) and early-season crops (2000), respectively. The late-season crops had shorter growth duration, received less rainfall, and experienced cooler temperatures during establishment and the early vegetative stage, and warmer temperatures during the reproductive phase than the early-season crops. Intercropping had no significant effect on the growth and tuber yields of cassava, or on phenology (i.e. time to vegetative growth, flowering and fruiting) and pod yield of okra in both seasons. However, it reduced weed growth by 35–57%, and kept both the soil and canopy environments of cassava cooler by 2·3–5·8 °C and more moist by 15–30 g/kg, compared with monoculture. The phenology and pod yields of the early- and late-season okra in both cropping systems were dependent on sowing date, indicating that okra production is only suitable at particular sowing dates in both seasons. July-sown okra in the 1999 late-season and May-sown crop in the 2000 early-season took progressively the longest time (i.e. 3–10 and 2–5 days, respectively) to flower and fruit, but these crops controlled weeds and modified the cassava environment better than the rest, and gave the highest fresh pod yields and economic returns. It took okra pods longer to reach marketable size in the late season than early season (i.e. 5–9 v. 2–6 days). It is concluded that the optimal sowing date to attain maximum pod yield and economic returns from late-season okra is July or August and from early-season crop is May or early June. Bearing in mind financial constraints and production costs, the optimal season target for maximum edible pods is the early season and for maximum economic returns is the late season.
Use of CERES-Wheat model for wheat yield forecast in central Indo-Gangetic Plains of India
Authors: NAIN A. S. , DADHWAL V. K. , SINGH T. P.
Published: July 2004

A methodology was developed for large area yield forecast using a crop simulation model and a discrete technology trend, and was applied to the coherent wheat yield variability zones of Eastern Uttar Pradesh, India. The approach consisted of three major steps: (a) prediction of technology trend yield using historical yield series of the region; (b) prediction of weather-induced deviation in wheat yield using CERES-Wheat simulation model and relating weather-induced deviation in simulated yield to deviation in observed yield deviations from technology trend; and (c) final yield forecast by incorporating predicted yield deviation in trend predicted yield. The regression coefficients for step (b) were generated using 10 years' data (1984/85–1994/95) and the reliability of the approach was tested on a data set of 5 years' independent data (1995/96–1999/2000). The results showed that this approach could capture year-to-year variability in large area wheat yield with reasonable accuracy. The Root Mean Square Error (RMSE) between observed and predicted yield was reported as 0·098 t/ha for the mean yield of 2·072 t/ha (4·72%). However, the RMSE was slightly higher in the forecasting period in comparison to the calibration period. The use of this methodology for issuing the pre-harvest forecast and the effect of upgrading the technology trend were also studied. The pre-harvest forecasts were made using in-season weather data up to the end of February and climatic-normal for the rest of the wheat-growing season, which showed good agreement with observed wheat yields. The forecasts of wheat yield for the season 1999/2000 were made using the technology trend up to 1994/95 and the updated technology trend up to 1998/99, which showed that the RMSE fell in the latter case, from 4·10 to 2·50%.
Water stress, photosynthesis, seed sucrose levels and seed growth in soybean
Authors: EGLI D. B. , BRUENING W. P.
Published: July 2004

The rate of growth of individual seeds of soybean (Glycine max L. Merrill) is determined, in part, by the concentration of sucrose in the seed. Water stress during seed filling reduces photosynthesis, but the effect on seed sucrose concentration is not well understood. Soybean plants (cultivars Elgin 87 and Asgrow 232HS) were exposed to water stress from early in the seed-filling period until maturity in field and greenhouse experiments. Stress reduced yield (5–38%) and seed size (11–35%) but it did not affect the number of seeds. Stress accelerated leaf senescence as shown by a more rapid decline in leaf photosynthesis in both experiments. Seed-growth rate and cotyledon sucrose concentrations (expressed on a mM basis using the bulk water content of the cotyledons) during the linear phase of seed growth were not affected by stress in either experiment. Thus, water stress during seed filling had no direct effect on seed growth; its only effect was to accelerate leaf senescence, which shortened the seed-filling period and resulted in smaller seeds. Strategies to reduce yield loss from water stress during seed filling should focus on leaf senescence instead of seed growth.
Variability in yield of four grain legume species in a subhumid temperate environment I. Yields and harvest index
Authors: AYAZ S. , McKENZIE B. A. , HILL G. D. , McNEIL D. L.
Published: July 2004

In 1998/99 and 1999/2000, field trials were conducted to try to explain why grain legume yields and harvest index are more variable than many other crops. Treatments involved varying plant populations and sowing depths and were selected to maximize plant variability. Both yields and harvest index were variable. Total dry matter (TDM) production generally increased as plant population increased up to twice the optimum population. Increases ranged from 80 to 130% with lupins producing the highest yields of 878 and 972 g/m2 of TDM in 1998/99 and 1999/2000 respectively. While plants sown at 10 cm depth produced more TDM than did plants sown at 2 cm, the difference was only 3%. Seed yields followed similar trends to TDM, with maximum yields (mean of 403 g seed/m2) produced at twice the optimum population. Crop harvest index (CHI) was quite variable and ranged from 0·31 to 0·66. Crop HI was lowest (0·43) at the lowest population and increased to 0·55 at twice the optimum plant population. In both seasons, lentil had the highest CHI and lupin the lowest. While CHI was variable there were very close relationships between seed yield and TDM which suggested that maximum seed yield depends on maximizing TDM production. The results also suggest that growers should increase population by a factor of two to obtain maximum seed yields.