bluuebunny/crossref_metadata_2025 huggingface dataset:
Observer variability in optic disc assessment: implications for glaucoma shared care
Authors: Harper Robert , Reeves Barnaby , Smith George
Published: September 2002

Demonstrating that optometrists can make valid and reliable assessments of optic disc features is an important prerequisite for establishing schemes for shared care/co‐management. Previous studies have estimated observer variability among experts in the assessment of optic disc cupping, but there has been a paucity of information on observer variability amongst optometrists. This paper describes a study to investigate intra‐ and inter‐observer variability for a range of disc features, as graded by both ophthalmologists and optometrists. Five observers (three optometrists and two ophthalmologists) graded 48 stereo‐pairs of optic disc photographs from 48 patients on two separate occasions. Each observer graded the following features: vertical and horizontalC/D ratios, narrowest rim width, the presence/absence of a disc haemorrhage, focal pallor of the neuroretinal rim, peri‐papillary atrophy, the steepness of the cup‐edge and the presence/absence of the cribriform sign. The average intra‐ and inter‐observer standard deviation (SD) of differences are, respectively, 0.11 and 0.19 for the verticalC/D ratios and 0.10 and 0.18 for the horizontalC/D ratios. For the verticalC/D ratio the average weighted kappa (κw) is 0.79 within observers and 0.46 between observers. Percentage agreements for the presence/absence of a disc haemorrhage range from 96 to 100% (averageκ=0.92) within observers and from 90 to 98% (averageκ=0.77) between observers. For other disc features, averageκw values range from 0.67 to 0.71 within observers and from 0.23 to 0.46 between observers. Intra‐and inter‐observer comparisons (within and between different professionals) across all disc features are comparable for the optometrists and ophthalmologists, thus demonstrating that optometrists can make valid assessments of disc features. The implications for shared care are discussed.
Pulse‐duration threshold functions obtained at the MWS/LWS cone antagonistic locus
Authors: Schwartz Steven H.
Published: September 2002

Pulse‐duration threshold functions were determined for spectral increments in the region of the Sloan notch (580 nm) as well as for 440 and 640 nm and white increments flashed on a spatially coincident white background. While increments of 440 and 640 nm elicited traditional pulse‐duration functions with decreasing thresholds as the duration increased, functions obtained with 580 nm and white increments manifested a minima at about 50 ms. These data support the notion that stimuli in the region of Sloan's notch can be detected by an achromatic mechanism that may integrate sub‐threshold ON and OFF responses, thereby maximizing detection sensitivity.
Age‐related changes of defocus‐specific contrast sensitivity in healthy subjects
Authors: Nio Y. K. , Jansonius N. M. , Fidler V. , Geraghty E. , Norrby S. , Kooijman A.C.
Published: September 2002

To investigate the effect of defocus on contrast sensitivity as a function of age in healthy subjects, the through focus contrast sensitivity was measured in 100 healthy subjects aged 20–69. Defocus‐specific changes in contrast sensitivity reflect age‐related changes in the optics of the eye. Tests were performed in cycloplegic eyes varying artificial pupil size (2, 4 and 6 mm), defocus (−1 to +2 D), and spatial frequency (1–16 cpd). Integrated contrast sensitivity was taken as a measure for the total amount of visual information transferred by the optical media.

At optimal focus, integrated contrast sensitivity and log contrast sensitivity at 8 cpd showed a significant age‐related decline. The log contrast sensitivity at 1 cpd appeared to be independent of age. The depth of focus for a 4‐mm pupil increased significantly with age, even though contrast sensitivity at +2 D defocus decreases with age too, but not as much as the contrast sensitivity at optimal focus. Our study indicates that the effect of defocus on contrast sensitivity decreases with age; this was attributed to age‐related changes in the optical media.
Detection, aetiology and management of conjunctival intraepithelial neoplasia
Authors: Jaworski Andrew , Wolffsohn James S. , Napper Genevieve A.
Published: September 2002

Conjunctival intraepithelial neoplasia (CIN) are considered to be the third most common ocular tumour and the most common tumour of the ocular surface. Due to their malignant potential, they must be carefully differentially and promptly treated. A recurrence rate of approximately 30% leads to the need for monitoring of patients even after successful treatment. This article presents several cases of CIN and reviews their histopathology, aetiology, appearance, differential diagnosis and management. Typical patient presentations and prognoses are also discussed.
Grading scales for contact lens complications
Authors: Efron Nathan
Published: September 2002

Grading scales have been developed to assist practitioners in recording the level of severity of ocular complications of contact lens wear. Eight common complications are depicted in five levels of severity—from grade 0 (normal) to grade 4 (severe). The intersubject variance in grading was determined to be 1.0 scale units, which by coincidence concurs exactly with the key design strategy of the grading scales that each grading step of 1.0 corresponds to a clinically significant difference in severity.
The mechanism of type IA topoisomerases
Authors: Dekker N. H. , Rybenkov V. V. , Duguet M. , Crisona N. J. , Cozzarelli N. R. , Bensimon D. , Croquette V.
Published: September 2002

The topology of cellular DNA is carefully controlled by enzymes called topoisomerases. By using single-molecule techniques, we monitored the activity of two type IA topoisomerases in real time under conditions in which single relaxation events were detected. The strict one-at-a-time removal of supercoils we observed establishes that these enzymes use an enzyme-bridged strand-passage mechanism that is well suited to their physiological roles and demonstrates a mechanistic unity with type II topoisomerases.
Type III secretion systems and the evolution of mutualistic endosymbiosis
Authors: Dale Colin , Plague Gordon R. , Wang Ben , Ochman Howard , Moran Nancy A.
Published: September 2002

The view that parasites can develop cooperative symbiotic relationships with their hosts is both appealing and widely held; however, there is no molecular genetic evidence of such a transition. Here we demonstrate that a mutualistic bacterial endosymbiont of grain weevils maintains and expresses
inv
/
spa
genes encoding a type III secretion system homologous to that used for invasion by bacterial pathogens. Phylogenetic analyses indicate that
inv
/
spa
genes were present in presymbiotic ancestors of the weevil endosymbionts, occurring at least 50 million years ago. The function of
inv/spa
genes in maintaining symbiosis is demonstrated by the up-regulation of their expression under both
in vivo
and
in vitro
conditions that coincide with host cell invasion.
Singularity in budding: A role for the evolutionarily conserved small GTPase Cdc42p
Authors: Caviston Juliane P. , Tcheperegine Serguei E. , Bi Erfei
Published: September 2002

The budding yeast
Saccharomyces cerevisiae
initiates polarized growth or budding once per cell cycle at a specific time of the cell cycle and at a specific location on the cell surface. Little is known about the molecular nature of the temporal and spatial regulatory mechanisms. It is also unclear what factors, if any, among the numerous proteins required to make a bud are involved in the determination of budding frequency. Here we describe a class of
cdc42
mutants that produce multiple buds at random locations on the cell surface within one nuclear cycle. The critical mutation responsible for this phenotype affects amino acid residue 60, which is located in a domain required for GTP binding and hydrolysis. This mutation bypasses the requirement for the essential guanine-nucleotide-exchange factor Cdc24p, suggesting that the alteration at residue 60 makes Cdc42p hyperactive, which was confirmed biochemically. This result also suggests that the only essential function of Cdc24p is to activate Cdc42p. Together, these data suggest that the temporal and spatial regulation of polarized growth converges at the level of Cdc42p and that the activity of Cdc42p determines the budding frequency.
Biosynthesis of terpenes: Studies on 1-hydroxy-2-methyl-2-(
E
)-butenyl 4-diphosphate reductase
Authors: Adam Petra , Hecht Stefan , Eisenreich Wolfgang , Kaiser Johannes , Gräwert Tobias , Arigoni Duilio , Bacher Adelbert , Rohdich Felix
Published: September 2002

Earlier
in vivo
studies showed the involvement of IspH protein in the conversion of 1-hydroxy-2-methyl-2-(
E
)-butenyl 4-diphosphate into isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). We have demonstrated now that cell extract of an
Escherichia coli
strain engineered for hyperexpression of the
ispH
(
lytB
) gene catalyzes the
in vitro
conversion of 1-hydroxy-2-methyl-2-(
E
)-butenyl 4-diphosphate into IPP and DMAPP. The reaction requires NADH, FAD, divalent cations (preferably Co
2+
), and probably one or more as-yet-unidentified proteins. The low intrinsic catalytic activities of wild-type
E. coli
cell extract and isolated chromoplasts of red pepper (
Capsicum annuum
) are enhanced by the addition of purified recombinant IspH protein.
CFTR chloride channels are regulated by a SNAP-23/syntaxin 1A complex
Authors: Cormet-Boyaka Estelle , Di Anke , Chang Steven Y. , Naren Anjaparavanda P. , Tousson Albert , Nelson Deborah J. , Kirk Kevin L.
Published: September 2002

Soluble
N-
ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) mediate membrane fusion reactions in eukaryotic cells by assembling into complexes that link vesicle-associated SNAREs with SNAREs on target membranes (t-SNAREs). Many SNARE complexes contain two t-SNAREs that form a heterodimer, a putative intermediate in SNARE assembly. Individual t-SNAREs (e.g., syntaxin 1A) also regulate synaptic calcium channels and cystic fibrosis transmembrane conductance regulator (CFTR), the epithelial chloride channel that is defective in cystic fibrosis. Whether the regulation of ion channels by individual t-SNAREs is related to SNARE complex assembly and membrane fusion is unknown. Here we show that CFTR channels are coordinately regulated by two cognate t-SNAREs, SNAP-23 (synaptosome-associated protein of 23 kDa) and syntaxin 1A. SNAP-23 physically associates with CFTR by binding to its amino-terminal tail, a region that modulates channel gating. CFTR-mediated chloride currents are inhibited by introducing excess SNAP-23 into HT29-Cl.19A epithelial cells. Conversely, CFTR activity is stimulated by a SNAP-23 antibody that blocks the binding of this t-SNARE to the CFTR amino-terminal tail. The physical and functional interactions between SNAP-23 and CFTR depend on syntaxin 1A, which binds to both proteins. We conclude that CFTR channels are regulated by a t-SNARE complex that may tune CFTR activity to rates of membrane traffic in epithelial cells.
Bcrp1gene expression is required for normal numbers of side population stem cells in mice, and confers relative protection to mitoxantrone in hematopoietic cellsin vivo
Authors: Zhou Sheng , Morris John J. , Barnes Yuxiao , Lan Lubin , Schuetz John D. , Sorrentino Brian P.
Published: September 2002

Hematopoietic stem cells (HSCs) can be identified by a “side population” (SP) phenotype. Previous studies have implicated the ATP binding cassette transporter genesMdr1a/1band/orBcrp1in the SP phenotype. To define the relative role of these transporters, we generated Bcrp1 null mice and evaluated HSCs both functionally and phenotypically. Loss ofBcrp1gene expression, but not Mdr1a/1b, led to a significant reduction in the number of SP cells in the bone marrow and in skeletal muscle. In the bone marrow, there was a nearly absolute loss of lineage negative, c-Kit-positive, Sca-1-positive SP cells, and the residual SP cells were depleted of repopulating cells in a transplant assay, demonstrating thatBcrp1expression is necessary for the SP phenotype in HSCs. Furthermore, Bcrp1 null hematopoietic cells were significantly more sensitive to mitoxantrone in drug-treated transplanted mice. These results show thatBcrp1gene expression alone defines the SP stem cell phenotype, and suggest that the physiological function ofBcrp1expression in HSCs is to provide protection from cytotoxic substrates.
Directional selection is the primary cause of phenotypic diversification
Authors: Rieseberg Loren H. , Widmer Alex , Arntz A. Michele , Burke John M.
Published: September 2002

Selection is widely accepted as the principal force shaping phenotypic variation within populations. Its importance in speciation and macroevolution has been questioned, however, because phenotypic differences between species or higher taxa sometimes appear to be nonadaptive. Here, we use the quantitative trait locus (QTL) sign test to evaluate the importance of directional selection in phenotypic divergence. If a trait has a history of directional selection, QTL effects should be mostly in the same direction; otherwise QTLs with antagonistic effects should be common. Analysis of QTL effects for 572 traits from 86 studies revealed significantly fewer antagonistic QTLs than expected under neutrality, a result that validates Darwin's claim that phenotypic diversification is caused mainly by selection. Moreover, interspecific trait differences were more strongly or consistently selected than intraspecific differences, strengthening a growing consensus among students of speciation that directional selection is the primary cause of speciation. Contrary to studies of selection in contemporary populations, life history traits appear to be selected more strongly than morphological traits, but traits related to the timing of development are weakly selected relative to most other traits.
Application of charge density methods to a protein model compound: Calculation of Coulombic intermolecular interaction energies from the experimental charge density
Authors: Li Xue , Wu Guang , Abramov Yuriy A. , Volkov Anatoliy V. , Coppens Philip
Published: September 2002

A combined experimental and theoretical charge density study of the pentapeptide Boc-Gln-d-Iva-Hyp-Ala-Phol (Boc, butoxycarbonyl; Gln, glutamine; Iva, isovaline; Hyp, hydroxyproline; Ala, ethylalanine; Phol, phenylalaninol) is described. The experimental analysis, based on synchrotron x-ray data collected at 20 K, is combined withab initiotheoretical calculations. The topologies of the experimental and theoretical densities are analyzed in terms of the atoms in molecules quantum theory. Topological parameters, including atomic charges and higher moments integrated over the atomic basins, have been evaluated with the programtopxdand are used to calculate the electrostatic interactions between the molecules in the crystal. The interaction energies obtained after adding dispersive and repulsive van der Waals contributions agree quite well with those based on M-B3LYP/6–31G** dimer calculations for two of the three dimers in the crystal, whereas for the third a larger stabilization is obtained than predicted by the calculation. The agreement with theory is significantly better than that obtained with multipole moments derived directly from the aspherical atom refinement. The convergence of the interaction as a function of addition of successively higher moments up to and including hexadecapoles (l= 4) is found to be within 2–3 kJ/mol. Although shortcomings of both the theoretical and experimental procedures are pointed out, the agreement obtained supports the potential of the experimental method for the evaluation of interactions in larger biologically relevant molecules.
Dual localization of human DNA topoisomerase IIIα to mitochondria and nucleus
Authors: Wang Yong , Lyu Yi Lisa , Wang James C.
Published: September 2002

The human
TOP3α
gene encoding DNA topoisomerase IIIα (hTop3α) has two potential start codons for the synthesis of proteins 1,001 and 976 aa residues in length. The sequence of the N-terminal region of the 1,001-residue form resembles signal peptide sequences for mitochondrial import, and fluorescence microscopy shows that the addition of as few as the first 34 aa of the 1,001-residue form of hTop3α to a green fluorescent protein can direct the chimeric protein to mitochondria. Biochemical analyses of subcellular fractions of HeLa cells further demonstrate that a distinctive fraction of hTop3α is present inside mitochondria, as evidenced by its resistance to proteinase K. This fraction constitutes several percent of the enzyme in the nuclear fraction, suggesting that the distribution of the mitochondrial and nuclear forms of hTop3α is roughly in proportion to the DNA contents of these cellular compartments. The presence of a type IA DNA topoisomerase in the mitochondria of other eukaryotes is supported by an examination of the amino acid sequences of mouse and
Drosophila
DNA topoisomerase IIIα and
Schizosaccharomyces pombe
DNA topoisomerase III. Given the presence of at least one type IA DNA topoisomerase in all forms of life examined to date, the finding of a type IA enzyme in mitochondria further supports the notion of a key role of such enzymes in DNA transactions.
Cbl-directed monoubiquitination of CIN85 is involved in regulation of ligand-induced degradation of EGF receptors
Authors: Haglund Kaisa , Shimokawa Noriaki , Szymkiewicz Iwona , Dikic Ivan
Published: September 2002

Addition of ubiquitin or ubiquitin chains to target proteins leads to their mono- or polyubiquitination, respectively. Whereas polyubiquitination targets proteins for degradation, monoubiquitination is thought to regulate receptor internalization and endosomal sorting. Cbl proteins are major ubiquitin ligases that promote ligand-dependent polyubiquitination and degradation of receptor tyrosine kinases. They also recruit CIN85-endophilin in the complex with activated receptors, thus controlling receptor endocytosis. Here we show that the adaptor protein CIN85 and its homologue CMS are monoubiquitinated by Cbl/Cbl-b after epidermal growth factor (EGF) stimulation. Monoubiquitination of CIN85 required direct interactions between CIN85 and Cbl, the intact RING finger domain of Cbl and a ubiquitin acceptor site present in the carboxyl terminus of CIN85. Cbl-b and monoubiquitinated CIN85 are found in the complex with polyubiquitinated EGF receptors during prolonged EGF stimulation and are degraded together in the lysosome. Dominant interfering forms of CIN85, which have been shown previously to delay EGF receptor degradation, were also impaired in their monoubiquitination. Thus, our data demonstrate that Cbl/Cbl-b can mediate polyubiquitination of cargo as well as monoubiquitination of CIN85 to control endosomal sorting and degradation of receptor tyrosine kinases.
Differential effects of gender on perceptions of teleworking by human resources managers
Authors: Pérez Pérez Manuela , Pilar de Luis Carnicer Mu , Martínez Sánchez Angel
Published: September 2002

This paper anayzes the differences of male and female human resource (HR) managers’ perceptions on the benefits, barriers and feasibility of teleworking adoption in a sample of Spanish companies. The results indicate that teleworking is seen as more feasible where there are a large number of female employees, and that female HR managers perceive teleworking differently than male HR managers. Women tend to be more positive about the potential of teleworking.
Human resource strategy for Kenyan women smallholders
Authors: Gundu Shibanda George , Ingado Seru Jemymah
Published: September 2002

Smallholder is a relative term, used to mean a small‐scale farmer and also peasant rural‐based holders. They constitute over 85 per cent of the rural population, mainly tilling the land and contributing 90 per cent of the nation’s agricultural produce. There is an imbalance against the Kenyan smallholder women’s participation in development although they are the pillars of rural and national development. It is known generally that the African women are by default excluded from the center stage of the developmental decision‐making process. One crucial factor is the apparent low numbers of women as head of households besides being in key management and decision‐making positions. Essentially this work is built on the understanding that opening educational opportunities, erasing backward‐looking discriminatory practices and putting capacity‐building initiatives in place will increase women’s participation in the decision‐making process. The key questions see African women generally as educationally disadvantaged, affected by discriminatory practices and needing professional and management capacity‐building in the smallholder sector.
NONLINEAR VARIABILITY IN THE GEOMAGNETIC SECULAR VARIATION OF THE LAST 150 YEARS
Authors: DE SANTIS A. , BARRACLOUGH D. , TOZZI R.
Published: September 2002

A nonlinear forecasting analysis has been applied to the secular variation of the three-component annual means of 14 observatories, unevenly distributed over the Earth's surface (12 in the northern and 2 in the southern hemisphere) and spanning the last 150 years. All results were in agreement, either in terms of possible evidence of chaos (as opposed to the hypothesis of white or colored noise), or in terms of the Kolmogorov entropy, confirming previous results obtained with only three European observatories, i.e. it is practically impossible to predict the secular variation of the geomagnetic field more than six years into the future.
MEASUREMENTS OF FRACTAL SCALING OF A PASSIVE SCALAR IN UNIFORMLY SHEARED TURBULENCE
Authors: MARINEAU-MES S. , TAVOULARIS S.
Published: September 2002

Statistics and scaling properties of temperature traces in a uniformly sheared, nearly homogeneous turbulent flow have been investigated experimentally. Heat was injected continuously from an electrically heated, thin ribbon and the fluctuating temperature was measured with a cold wire. By virtue of Taylor's "frozen flow" approximation, the temperature time series was interpreted as a linear section through the heated/unheated fluid interface. The box-counting method was used to reveal the possible fractal scaling of this interface. The results are somewhat mixed. Temperature traces taken away from the centerline of the heated wake appear to exhibit some scaling over a limited range, with a fractal dimension of 0.38 ± 0.05, which, according to the intersection rule, would imply a fractal dimension of about 2.38 for the scalar interface. In contrast, temperature traces taken near the centerline did not show any scaling, but this may be due to the high "density" of such traces, which renders the use of the box-counting algorithm questionable.
SOME APPLICATIONS OF THE FRACTAL PARAMETRIC-HOMOGENEOUS FUNCTIONS
Authors: BORODICH FEODOR M.
Published: September 2002

The purpose of this paper is to present some recent results concerning applications of so-called parametric-homogeneous (ph) functions to some problems of solid mechanics. The ph-functions have often fractal graphs and can be nowhere differentiable. An example of ph-function is the Weierstrass-Mandelbrot one. We introduce some ways of construction of the ph-function of both arbitrary degree and fractal dimension. We consider the discrete Hertz problem of contact between a punch, whose shape is described by a positive ph-function, and a deformable half-space. General expressions for changes of all functions, giving the solutions of the contact problems for a fractal punch, are derived exactly, without solving the field equations.
STATION LAYOUTS IN THE PRESENCE OF LOCATION CONSTRAINTS
Authors: BOSE PROSENJIT , KRANAKIS EVANGELOS , KAKLAMANIS CHRISTOS , KIROUSIS LEFTERIS M. , KRIZANC DANNY , PELEG DAVID
Published: September 2002

In wireless communication, the signal of a typical broadcast station is transmitted from a broadcast center p and reaches objects at a distance, say, r from it. In addition there is a radius r0, r0 < r, such that the signal originating from the center of the station is so strong that human habitation within distance r0 from the center p should be avoided. In other words, points within distance r0 from the station comprise a hazardous zone. We consider the following station layout proble: Cover a given planar region that includes a collection of buildings with a minimum number of stations so that every point in the region is within the reach of a station, while at the same time no interior point of any building is within the hazardous zone of a station. We give algorithms for computing such station layouts in both the one- and two-dimensional cases.
DYNAMIC CHARACTERISTICS OF SHEET ROLLING INSTABILITY
Authors: LIN Y.-J. , SUH C. S. , NOAH S. T.
Published: September 2002

Dynamic rolling instability known as fifth-octave chatter is studied using a nonlinear model developed to describe the responses of work rolls subjected to the exertion of sheet forces of various spectral characteristics. The model enables the dynamic instability of sheet rolling to be correlated with work roll stiffness, rolling speed, inter-stand tension, roll-bite entry and exit thickness, and the sheet force resulted from the interactive action of the work roll with the plastic deformation of the rolled strip. It is found that roll-bit elastic-plastic deformation sheet force is nonlinearly coupled with the rollstack stiffness and also plays a dominant role in affecting rolling instability. In addition, whenever the frequency spectrum of the normal sheet forces containing spectral components that match the fundamental modes of the roll stand, resonance-like beating would occur. This highly linear physical phenomenon, which is accompanied by large vibration amplitudes in the active work rolls, is recognized as chatter. Although many different dynamic modes of instability including mode excitation and beating are induced in response to sheet forces of nonlinear and non-stationary in nature, however, the rolling system never responds chaotically.
DESIGN AND SECOND-ORDER ANALYSIS OF TRUSSES COMPOSED OF ANGLE SECTIONS
Authors: SUN X. , CHAN S. L.
Published: September 2002

Extensive work has been carried out on the advanced analysis of frames consisting of members of symmetrical cross-section, but trusses composed of angle sections were not investigated in detail by the advanced analysis. This paper describes the application of advanced analysis to structures composed of angle sections. The effects of load eccent-ricity and finite stiffness at connections are also allowed for. The difficulties of assuming an effective length factor and classification of connections for angle column design in the computer analysis are avoided. The method produces a consistent result with the column buckling curves in design codes and with the results by other researchers.
THREE-DIMENSIONAL NON-PRISMATIC BEAM-COLUMNS
Authors: LEVY R. , GAL E.
Published: September 2002

This paper is concerned with three-dimensional straight beam-columns with no warping whose cross sections vary along the axis in a uniform manner with respect to the principal directions. The basic four coupled differential equations governing the behavior of 3D beam-columns are first rederived using the method of perturbations. These equations are reformulated to include varying cross sections. Finally, a 6 × 6 stiffness matrix (which is sufficient to describe 3D behavior) is computed by solving the equations 6 times for a sequence of appropriate discontinuities. The finite difference method is employed for that purpose. Timoshenko's closed form solution for the buckling load of a tapered column is chosen for comparison with that obtained by the proposed formulation. Effects of twist are also presented.
INDIVIDUAL RECOGNITION OF PIGLETS BY SOWS IN THE EARLY POST-PARTUM PERIOD
Authors: Maletínská Jitka , Špinka Marek , Víchová Jitka , Stěhulová Ilona
Published: September 2002

We investigated whether domestic sow discriminates one day old piglets based on their individual odours or based on some odour common to the whole litter. We manipulated the contacts between sow and piglets during the first 24 h post partum in such a way that produced 4 types of piglets, as combinations of two factors: relatedness and familiarity. We used ten pairs of sows individually housed in farrowing pens in which parturitions were induced on the same day. When the manipulations were finished, each sow was subjected to two testing situations. First it was a 5 min choice test in which the sow could show her preference for the 4 types of anaesthetized (immobile and mute) piglets: Own Familiar, Own Unfamiliar, Alien Familiar and Alien Unfamiliar. Second the sow was subjected to three 2.5 min preference tests with the following combinations of dyads of awake piglets: Own Familiar vs Alien Unfamiliar; Own Familiar vs Own Unfamiliar; Alien Unfamiliar vs Alien Familiar. We recorded the frequency and duration of visits and the grunting rate of sow with respect to each piglet type, in the test with awake piglets we also recorded piglets' vocalisation and movement. In the test with anaesthetized piglets we found a significant effect of piglet type on the duration of visits (F
(3,16) = 3.94, p = 0.014). The significant difference between Own Unfamiliar and Own Familiar piglets indicates that sows use the individual odours of piglets to discriminate between own and alien ones. The number of visits to individual piglets was also affected by piglet type (F
(3,16) = 2.71, p = 0.055), with sows visiting Own Familiar piglets significantly more often than Alien Unfamiliar ones. In none of the three preference tests with awake piglets did the sows show significant preference for a specific type of piglet. However the sows' visits in the piglets was affected by the piglets' activity. In periods when both the piglets were moving the sow spent a greater proportion of time by visiting them (Students t-test, N = 11, mean = 0.12, p = 0.0014) then during periods when only one or none of the piglets was moving. Sows also spent a greater proportion of time visiting the piglets when they were vocalising (Students t-test, N = 11, mean = 0.129, p = 0.019) than when they were not. The study shows that early recognition of piglets by sows is probably mediated by the individual odour of each piglet and that kinetic and acoustic cues augment the motivation to reunite with the piglets and this may then override the willingness to discriminate among them.
Substituent Effect on the Rate of the Hydroxyl and Phenyl Radical Spin Trapping with Nitrones
Authors: Sueishi Yoshimi , Yoshioka Chiharu , Olea-Azar Claudio , Reinke Lester A , Kotake Yashige
Published: September 2002

Hydroxyl and phenyl radical spin trapping rates by α-phenyl-N-t-butylnitrone (PBN, N-benzylidene-t-butylamine N-oxide) and its analogs were determined using a competitive trapping method. Hydroxyl radical was generated from hydrogen peroxide in water using UV photolysis, in the presence of the selected spin trap plus 5,5-dimethyl-pyrroline N-oxide (DMPO). Phenyl radical was produced with UV photolysis of tetraphenyllead, and spin trapping was performed in benzene. Spin trapping rate constants were calculated using EPR signal intensity ratios for the DMPO spin adducts vs PBN-type spin adducts. The rate constants were strongly dependent on the kind of substituent in the spin trap; the magnitude of the substituent effect was also dependent on the kind of free radicals trapped, i.e., hydroxyl or phenyl radicals. For example, in phenyl radical trapping, the spin trapping rate in hydroxy-substituted PBNs followed Hammett’s equation, while there is no such correlation in hydroxyl radical trapping. Hydroxy-substituted PBNs such as 2-, 3-, and 4-hydroxy-PBNs showed much lower apparent spin trapping rates than that of PBN. The reaction between hydroxyl radical and phenoxyl group is a likely cause.
Coupled rotation within single F0F1 enzyme complexes during ATP synthesis or hydrolysis
Authors: Kaim Georg , Prummer Michael , Sick Beate , Zumofen Gert , Renn Alois , Wild Urs P , Dimroth Peter
Published: September 2002

F0F1 ATP synthases are the smallest rotary motors in nature and work as ATP factories in bacteria, plants and animals. Here we report on the first observation of intersubunit rotation in fully coupled single F0F1 molecules during ATP synthesis or hydrolysis. We investigate the Na+‐translocating ATP synthase of Propionigenium modestum specifically labeled by a single fluorophore at one c subunit using polarization‐resolved confocal microscopy. Rotation during ATP synthesis was observed with the immobilized enzyme reconstituted into proteoliposomes after applying a diffusion potential, but not with a Na+ concentration gradient alone. During ATP hydrolysis, stepwise rotation of the labeled c subunit was found in the presence of 2 mM NaCl, but not without the addition of Na+ ions. Moreover, upon the incubation with the F0‐specific inhibitor dicyclohexylcarbodiimide the rotation was severely inhibited.
Ethanol inhibits leptin‐induced STAT3 activation in Huh7 cells
Authors: Degawa-Yamauchi Mikako , Uotani Shigeo , Yamaguchi Yoshihiko , Takahashi Ryoko , Abe Takahiro , Kuwahara Hironaga , Yamasaki Hironori , Eguchi Katsumi
Published: September 2002

Leptin, an adipocyte‐derived hormone, regulates food intake and energy expenditure in the hypothalamus via its receptor, member of the class I cytokine receptor family. Leptin resistance has been observed in rodents and in humans. However, the mechanisms could not be explained in most cases of human obesity, except for rare cases with mutations in the leptin receptor. Recent reports demonstrated that ethanol inhibited the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway activated by some members of the class I cytokine receptor family. In this study, we examined the effects of ethanol on the leptin‐induced JAK/STAT signaling pathway using human hepatoma cell lines transiently expressing long form of the leptin receptor. A 30 min pretreatment with ethanol dose‐dependently inhibited the leptin‐induced STAT3 phosphorylation. Furthermore, to determine the time course of ethanol inhibitory effects, the cells were incubated in 10 mM ethanol for various times. Partial inhibition of leptin‐induced STAT3 activation was seen after 1 min of treatment with ethanol and completely inhibited after 30 min pretreatment. SB 202190, a p38 mitogen‐activated protein kinase (MAPK) inhibitor, partly prevented this inhibition by ethanol of leptin‐induced STAT3 activation. These findings suggest that ethanol time‐ and dose‐dependently inhibits the leptin action, in part via p38 MAPK.
Inhibitory effects do not depend on the subjective experience of pain during heterotopic noxious conditioning stimulation (HNCS): a contribution to the psychophysics of pain inhibition
Authors: Lautenbacher Stefan , Roscher Stephan , Strian Friedrich
Published: September 2002

Heterotopic noxious conditioning stimulation (HNCS) has been thought to give access to the diffuse noxious inhibitory controls (DNIC) in man, which can be activated in wide‐dynamic‐range neurons by noxious stimulation from remote areas of the body and form the neurophysiological basis of the phenomenon ‘pain inhibits pain’. The latter phenomenon suggests that the subjective experience of pain is a prerequisite for an inhibitory action. The necessity of using painful stimuli as conditioning and as test stimuli to produce inhibitory effects was investigated in the present study, using a HNCS paradigm. Twenty young men received conditioning stimuli created by tonic heat at painful and non‐painful levels, using either hot water (hand) or thermode (forearm). The test stimuli were phasic heat stimuli (thermode) at painful and non‐painful levels applied to the cheek. Only painful but not non‐painful heat as conditioning stimulus increased the heat pain threshold and decreased the ability to discriminate between painful heat of different intensities. These two findings are in accord with an inhibitory effect depending on a painful conditioning stimulus. However, the intensity ratings of the test stimuli indicated inhibitory effects of the conditioning stimuli also upon non‐painful levels. Furthermore, non‐painful heat as conditioning stimulus also appeared to be capable of decreasing the ratings of the test stimuli at painful levels. The latter two findings suggest: (i) that very strong but subjectively still non‐painful stimulation can trigger pain inhibitory effects and (ii) that also subjectively non‐painful stimuli are affected by inhibitory influences during HNCS.
A method for computing identity by descent probabilities and quantitative trait loci mapping with dominant (AFLP) markers
Authors: PÉREZ-ENCISO MIGUEL , ROUSSOT ODILE
Published: September 2002

Amplified fragment length polymorphisms (AFLPs) are a widely used marker system: the technique is very cost-effective, easy and rapid, and reproducibly generates hundreds of markers. Unfortunately, AFLP alleles are typically scored as the presence or absence of a band and, thus, heterozygous and dominant homozygous genotypes cannot be distinguished. This results in a significant loss of information, especially as regards mapping of quantitative trait loci (QTLs). We present a Monte Carlo Markov Chain method that allows us to compute the identity by descent probabilities (IBD) in a general pedigree whose individuals have been typed for dominant markers. The method allows us to include the information provided by the fluorescent band intensities of the markers, the rationale being that homozygous individuals have on average higher band intensities than heterozygous individuals, as well as information from linked markers in each individual and its relatives. Once IBD probabilities are obtained, they can be combined into the QTL mapping strategy of choice. We illustrate the method with two simulated populations: an outbred population consisting of full sib families, and an F2 cross between inbred lines. Two marker spacings were considered, 5 or 20 cM, in the outbred population. There was almost no difference, for the practical purpose of QTL estimation, between AFLPs and biallelic codominant markers when the band density is taken into account, especially at the 5 cM spacing. The performance of AFLPs every 5 cM was also comparable to that of highly polymorphic markers (microsatellites) spaced every 20 cM. In economic terms, QTL mapping with a dense map of AFLPs is clearly better than microsatellite QTL mapping and little is lost in terms of accuracy of position. Nevertheless, at low marker densities, AFLPs or other biallelic markers result in very inaccurate estimates of QTL position.
Sibship reconstruction in hierarchical population structures using Markov chain Monte Carlo techniques
Authors: THOMAS STUART C. , HILL WILLIAM G.
Published: September 2002

Markov chain Monte Carlo procedures allow the reconstruction of full-sibships using data from genetic marker loci only. In this study, these techniques are extended to allow the reconstruction of nested full- within half-sib families, and to present an efficient method for calculating the likelihood of the observed marker data in a nested family. Simulation is used to examine the properties of the reconstructed sibships, and of estimates of heritability and common environmental variance of quantitative traits obtained from those populations. Accuracy of reconstruction increases with increasing marker information and with increasing size of the nested full-sibships, but decreases with increasing population size. Estimates of variance component are biased, with the direction and magnitude of bias being dependent upon the underlying errors made during pedigree reconstruction.
The Kraemer Island macrodyke, East Greenland:
solidification of a flood basalt conduit
Authors: MOMME PETER , WILSON J. RICHARD
Published: September 2002

The Kraemer Island macrodyke that is exclusively exposed on Kraemer Island about 7 km west
of the Skaergaard Intrusion belongs to a regional dyke swarm termed the ‘Skaergaard-like dykes’ (or FG-1
dykes). Weakly modally layered olivine gabbros dominate the exposed parts of the intrusion that has a
width of 650 m to 1000 m. Plagioclase (core An68±2) and Ca-rich pyroxene (core Mg no. 79±1) grains are
normally zoned, whereas olivine grains (Fo50–65) are homogeneous. Calculated mineral–magma equilibria,
based on experimentally determined Mg–Fe magma–olivine and magma–clinopyroxene partition coefficients,
suggest that the observed olivine and clinopyroxene compositions in the gabbros cannot have
formed from a common parental magma. The unzoned nature of olivine grains and their iron-rich com-positions
relative to clinopyroxene suggest post-cumulus Mg–Fe exchange between olivine and interstitial
melt. A gabbroic pegmatite is developed in the centre of the intrusion along its entire exposed 5 km strike
length. Here, mineral zonation is limited and compositions are similar to rims of cumulus minerals in the
enveloping olivine gabbros. The pegmatite could therefore represent interstitial melt mobilized from gabbroic
cumulates that later accumulated and crystallized at its present stratigraphic location. Cumulus
olivines in the gabbros are close to equilibrium with Ca-rich pyroxene in the pegmatite. This is interpreted
as reflecting interstitial melt mobility during the late stages of solidification of the macrodyke. Chilled
margins are well preserved at the intrusion margins and are rich in Fe (14–15.3% FeOTOT), Ti (3–3.3%
TiO2) and light rare-earth elements ([La/Sm]N = 1.2–1.3), similar to magmas well represented in the overlying
sequence of contemporaneous High-Ti Series flood basalts. It is therefore likely that extensive wall-rock
melting adjacent to the macrodyke reflects continuous feeding of the overlying flood basalts through
the Kraemer Island macrodyke.
The Blackstones Bank igneous complex: geochemistry and
crustal context of a submerged Tertiary igneous centre
in the Scottish Hebrides
Authors: DICKIN A. P. , DURANT G. P.
Published: September 2002

The Blackstones Bank, located about 60 km WSW of the Isle of Mull in Western Scotland,
is a submarine plutonic complex in the British Tertiary Igneous Province. Geochemical and isotopic
analysis of gabbros, microgabbros and basic dykes shows that the magmas interacted strongly with
crustal rocks during their emplacement. The isotopic signature of the contaminated Tertiary intrusions
shows no evidence of any interaction with Archaean basement, despite the location of the
Blackstones complex to the west of the Great Glen fault. Instead, the Blackstones rocks have crustal
signatures resembling the Proterozoic basement and cover rocks of western Islay. It is therefore
inferred that Early Proterozoic crust extends to the west of the Great Glen fault at this point on the
Scottish continental shelf. In addition, the occurrence of similar isotopic signatures in Tertiary
igneous rocks east of the Loch Gruinard fault confirms that Early Proterozoic basement extends
under the Grampian block of mainland Scotland. When combined with published evidence from the
Rockall bank, the new data constrain the location of an Archaean–Proterozoic crustal suture with a
WNW trajectory which cuts across the continental shelf of northwest Britain.
The environmental impact of genetically modified (GM) crops: a review
Authors: DALE P. J.
Published: September 2002

Evaluating environmental impact is more complex than statistical analysis; it requires value judgements about which kinds of environmental impacts are acceptable and which are not. The new EU Directive on the release and commercialization of genetically modified (GM) crops (2001-18-EC) includes a requirement for an assessment of indirect effects on the environment of farming practices associated with the introduction of a GM crop. There is also a requirement for post-commercialization monitoring to address impacts of scale and time. Both of these additions to the regulations present challenges in deciding how environmental impacts should be measured, and in judging their acceptability. Impacts can also be socio-economic. These frequently require scientific tools to help to resolve them. The demands by some food sectors for zero GM content in crop produce is likely to prove difficult or impossible to verify by analytical procedures. It will probably be necessary to agree on levels of tolerance of the presence of GM material in “non-GM” crop produce. It is important that the future use of biotechnology in agriculture is considered in the context of a broader discussion about our vision for agriculture and the environment over the coming decades.
Effects of white clover cultivars on biomass and yield in oat/clover intercrops
Authors: THORSTED M. D. , OLESEN J. E. , KOEFOED N.
Published: September 2002

Intercropping of spring cereals in a permanent stand of white clover (Trifolium repens L.) is a novel, low input cropping system, and little is known about the agronomic management of this system. An experiment was conducted over two growing seasons in 1998 and 1999 to determine the impact of a white clover intercrop on spring oat (Avena sativa L.) growth and grain yield at three different seeding rates of oat, and also to determine the effect of the three different white clover cultivars (cv. Aran, cv. S184 and cv. Milo), on weed pressure and growth of the oat crop. The clover cultivars differed in stolon morphology and leaf size. Oat in monoculture was included for comparison. The white clover intercrops did not reduce the weed pressure compared with oat in monoculture. Oat grain nitrogen concentration and content was raised in the intercropped oats. Grain yields in an intercrop were similar to those in a monoculture. Oat seeding densities did not affect grain yields. The oat grain yields in 1998 were significantly higher with S184 as intercrop. In 1999 it was directly opposite, grain yields were significantly lower with S184 as intercrop.
Nitrogen mineralization in soil from perennial grassland measured through long-term laboratory incubations
Authors: COLLINS A. , ALLINSON D. W.
Published: September 2002

Under perennial grasslands, nitrogen contained in organic matter becomes available at varying rates via mineralization throughout the growing season. The amount of N present at any given time indicates only the quantity immediately present, and does not include N which has already been removed either by leaching or uptake into the plant system, nor the N which will become available as organic matter breaks down over time. Long-term aerobic laboratory incubation methods have been used successfully to estimate potential N mineralization under various cropping conditions. They had not been used successfully, however, to estimate potential N availability under perennial grassland.

In this research, soil samples from two long-term perennial grassland sites were taken before and after N fertilizer application at rates of 0, 175, 350 and 525 kg/ha. The soils were incubated in the laboratory at 35 °C and were eluted at 2, 4, 8, 12, 16, 22 and 30-week intervals, the length of time prescribed for determining N mineralization potential. Because a plateau had not been reached, incubation was allowed to continue for 198 weeks and 148 weeks for the pre- and post-N samples, respectively. Total N was high, as was soil organic matter in both sets of soil samples. Nitrogen mineralization potential was underestimated after 30 weeks of incubation, and overestimated after 148 weeks. The closest agreement between N measured and the estimated N mineralization potential, came after 198 weeks of incubation. This study confirmed the high N-supplying capacity of soil under long-term perennial grasslands. It also indicated that the recommended 30-week period needed to estimate N mineralization potential under other cropping systems was insufficient for a perennial grassland soil. Cumulative differences in N mineralization were found with varying rates of N fertilizer application, but these differences were rarely seen on an individual weekly basis, nor were they significant at the termination of the experiment. The response to N application differed by site.