bluuebunny/crossref_metadata_2025_split huggingface dataset:
Laboratory study of wave bottom interaction in the bar formation on an erodible sloping bed
Authors: Dulou C. , Belzons M. , Rey V. 
Published: February 2004

The interaction between partially standing or almost progressive surface gravity waves and erodible beds is investigated in a small wave tank under nonbreaking wave conditions. The bed is initially flat and gently sloping, and the incident weakly nonlinear wave is either a regular wave (similar to a Stokes wave), or a regular wave superimposed on a free wave generated by the wave maker (bichromatic or bimodal wave). Accurate measurements of both the bed profile and the wave envelope are performed, showing a permanent coupled evolution of the wave field and of the bed shape. Sandbar formation is observed in the ultimate bed profile which reproduces the spatial modulations of the envelope of the first harmonic of the wave (e.g., the fundamental component). In the case of a pure regular wave, the interbar spacing is equal to half the local surface wavelength which corresponds to a first‐order Bragg resonance with the local wavenumber of the first harmonic satisfying the dispersion relation for small waves. In the case of a bimodal wave the preceding case is perturbed by a free wave of the same frequency and similar amplitude as the second harmonic of the regular wave. Then, nonlinear interactions between the first harmonic and the free wave occur, leading to sum and difference frequencies. The difference interaction modifies the amplitude and spatial modulation of the first harmonic. The Bragg resonance mechanism based on the first harmonic in the bar formation is then modified. However, in this case, the bed profile is also the replica of the envelope of the first harmonic of the wave: the perturbation induced in the first harmonic is also present in the bed shape. For partially standing bimodal waves, the Fourier analysis of the bed profile shows a second spatial modulation with the local wavenumber of the free wave. For almost progressive bimodal waves, a third modulation is found with the local wavenumber of the observed beating between the free wave and the second harmonic component of the wave.These modulations of the envelope of the first harmonic are recovered analytically through a partially standing bimodal wave modeling. This study confirms that the bar formation under nonbreaking wave conditions is controlled by the envelope of the first harmonic of the wave even if perturbed by a free wave.
Global geodetic signatures of the Antarctic Ice Sheet
Authors: James Thomas S. , Ivins Erik R. 
Published: February 2004

Four scenarios of present day Antarctic ice sheet mass change are developed from comprehensive reviews of the available glaciological and oceanographic evidence. The gridded scenarios predict widely varying contributions to secular sea level change
ranging from −1.1 to 0.45 mm/yr, and predict polar motion
and time‐varying low‐degree gravitational coefficients
that differ significantly from earlier estimates. A reasonably linear relationship between the rate of sea level change from Antarctica
A and the predicted Antarctic
is found for the four scenarios. This linearity permits a series of forward models to be constructed that incorporate the effects of ice mass changes in Antarctica, Greenland, and distributed smaller glaciers, as well as postglacial rebound (assuming the ICE‐3G deglaciation history), with the goal of obtaining optimum reconciliation between observed constraints on
and sea level rise
. Numerous viable combinations of lower mantle viscosity and hydrologie sources are found that satisfy “observed”
in the range of 1 to 2–2.5 mm/yr and observed
for degrees 2, 3, and 4. In contrast, rates of global sea level rise above 2.5 mm/yr are inconsistent with available
observations. The successful composite models feature a pair of lower mantle viscosity solutions arising from the sensitivity of
to glacial rebound. The paired values are well separated at
mm/yr, but move closer together as
is. increased, and, in fact, merge around
=2‐2.5 mm/yr, revealing an intimate relation between
and preferred lower mantle viscosity. This general pattern is quite robust and persists for different
solutions, for variations in source assumptions, and for different styles of lower mantle viscosity stratification. Tighter
constraints for l > 2 may allow some viscosity stratification schemes and source assumptions to be excluded in the future. For a given total observed
, the sea level rise from Antarctica
A is tightly constrained and ranges from 0 to + 1 mm/yr (corresponding to an ablating ice sheet) as estimates of
are raised from 1 to 2.5 mm/yr. However, when the degree 3 zonal harmonic constraint is removed, the solutions show little sensitivity to Antarctic mass balance, emphasizing the need for a well determined odd‐degree secular zonal harmonic for determining polar ice mass balance.
Investigations in the character of QTL affecting negatively correlated milk traits
Authors: Freyer G. , Sørensen P. , Kühn C. , Weikard R. 
Published: January 2004

SummaryThe primary aim of this study was to investigate the quantitative trait loci (QTL) on BTA6 that affect negatively correlated milk traits, using bivariate covariance component analysis of milk yield and fat (or protein) content, protein yield and fat content, and fat yield and protein content. A set of five different genetic models was adapted to differentiate trait‐specific QTL in close linkage from pleiotropy. Using a grand‐daughter design consisting of five half‐sib families from the German Holstein population and 298 sons genotyped for 16 microsatellite markers on BTA6, we found significant trait‐specific QTL for fat content and protein yield, 24 cM apart. Markers BM1329 and FBN12 bracketed the QTL for fat content, and the region between TGLA37 and FBN13 most likely harbours a QTL for protein yield. The analysis based on the close linkage model fully confirmed this result. Despite the pure QTL findings confirming results from the literature, distinguishing pleiotropic and closely linked QTL for competitive traits is a new aspect. Our multivariate analysis results did not suggest a pleiotropic QTL for the investigated negatively correlated traits. The QTL‐based trait correlations were discussed as an important aspect of modelling that needs to be considered in the future.
Bayesian comparison of test‐day models under different assumptions of heterogeneity for the residual variance: the change point technique versus arbitrary intervals
Authors: López‐Romero P. , Rekaya R. , Carabaño M. J. 
Published: January 2004

SummaryTest‐day milk yields from Spanish Holstein cows were analysed with two random regression models based on Legendre polynomials under two different assumptions of heterogeneity of residual variance which aim to describe the variability of temporary measurement errors along days in milk with a reduced number of parameters, such as (i) the change point identification technique with two unknown change points and (ii) using 10 arbitrary intervals of residual variance. Both implementations were based on a previous study where the trajectory of the residual variance was estimated using 30 intervals. The change point technique has been previously implemented in the analysis of the heterogeneity of the residual variance in the Spanish population, yet no comparisons with other methods have been reported so far. This study aims to compare the change point technique identification versus the use of arbitrary intervals as two possible techniques to deal with the characterization of the residual variance in random regression test‐day models. The Bayes factor and the cross‐validation predictive densities were employed for the model assessment. The two model‐selecting tools revealed a strong consistency between them. Both specifications for the residual variance were close to each other. The 10 intervals modelling showed a slightly better performance probably because the change point function overestimates the residual variance values at the very early lactation.
Genetic polymorphism at CSN1S2 locus in two endangered sicilian goat breeds
Authors: Marletta D. , Bordonaro S. , Guastella A. M. , D'Urso G. 
Published: January 2004

SummaryIn this study we surveyed two endangered Sicilian goat breeds (Girgentana and Argentata dell'Etna) for genetic polymorphism at the CSN1S2 locus. In a total of 537 goats, we detected CSN1S2A, CSN1S2B, CSN1S2C° (CSN1S2C + CSN1S2E), CSN1S2D, CSN1S2F and CSN1S2O alleles by means of various polymerase chain reaction (PCR), allele specific‐PCR (AS–PCR) and PCR‐restriction fragment length polymorphism (RFLP) reactions with the aim of improving the knowledge of the genetic resource of these two breeds. Three and five alleles, with six and twelve genotypes, were identified at CSN1S2 locus, in Girgentana and Argentata, respectively. Argentata dell'Etna showed a higher degree of genetic variation. The allelic and genotypic distribution seems to be significantly different (p < 0.001) in the two breeds. In Argentata the rare null allele (CSN1S2O) was found at low frequency (0.033); this genetic peculiarity makes its preservation worthwhile.
Implementation issues for Markov Chain Monte Carlo methods in random regression test‐day models
Authors: Jamrozik J. 
Published: January 2004

SummaryMarkov Chain Monte Carlo methods made possible estimation of parameters for complex random regression test‐day models. Models evolved from single‐trait with one set of random regressions to multiple‐trait applications with several random effects described by regressions. Gibbs sampling has been used for models with linear (with respect to coefficients) regressions and normality assumptions for random effects. Difficulties associated with implementations of Markov Chain Monte Carlo schemes include lack of good practical methods to assess convergence, slow mixing caused by high posterior correlations of parameters and long running time to generate enough posterior samples. Those problems are illustrated through comparison of Gibbs sampling schemes for single‐trait random regression test‐day models with different model parameterizations, different functions used for regressions and posterior chains of different sizes. Orthogonal polynomials showed better convergence and mixing properties in comparison with ‘lactation curve’ functions of the same number of parameters. Increasing the order of polynomials resulted in smaller number of independent samples for covariance components. Gibbs sampling under hierarchical model parameterization had a lower level of autocorrelation and required less time for computation. Posterior means and standard deviations of genetic parameters were very similar for chains of different size (from 20 000 to 1 000 000) after convergence. Single‐trait random regression models with large data sets can be analysed by Markov Chain Monte Carlo methods in relatively short time. Multiple‐trait (lactation) models are computationally more demanding and better algorithms are required.
Estimates of genetic parameters for Boran, Friesian and crosses of Friesian and Jersey with the Boran cattle in the tropical highlands of Ethiopia: reproduction traits
Authors: Demeke S. , Neser F. W. C. , Schoeman S. J. 
Published: January 2004

SummaryA study with the objectives of estimating breed differences, heterosis and recombination effects as well as heritabilities (h2) and repeatabilities (r2) for age at first calving (AFC), calving interval (CI), days open (DO) and number of services per conception (SPC) was conducted using reproduction records collected from 1496 cows comprising purebred Boran (B), Friesian (F), crosses of Friesian and Jersey (J) with Boran breeds. The crossbred cow groups included four F × B crosses [1/2F:1/2B(F1), 1/2F:1/2B(F2), 5/8F:3/8B and 3/4F:1/4B], three J × B crosses [1/2J:1/2B(F1), 1/2J:1/2B(F2) and 3/4J:1/4B] and one three‐breed cross (1/4F:1/4J:1/2B). The crossbreeding parameters were estimated using a repeatability animal model for CI, DO and SPC, and a unitrait animal model for AFC. The overall least‐squares means estimated were: 38.3 ± 0.26 months, 435 ± 4 days, 145 ± 10 days and 1.58 ± 0.03 (number) for AFC, CI, DO and SPC, respectively. The breed additive effects of F and J were only significant (p < 0.01) for AFC. Relative to B, both F and J additive contributions for AFC were −5.4 ± 0.5 and −5.5 ± 1.9 months, respectively. Crossing the B with F and J breeds also resulted in significant heterosis (p < 0.05) ranging from 10 to 21% in all traits. The estimated recombination loss was only significant for AFC (2.8 ± 1.0 months) for F × B crosses. Heritability estimates were high for AFC (0.44 ± 0.05) and low for CI (0.08 ± 0.03), DO (0.04 ± 0.03) and SPC (0.08 ± 0.02). The corresponding estimates for the repeatability (r2) were 0.14 ± 0.02 and 0.14 ± 0.02 for CI and DO, respectively. The permanent environmental effect for SPC was zero. These findings show that breed differences between F or J and B, and the individual cow variations are low for reproductive traits studied, except for AFC. Heterotic effects seem to be the major genetic causes for the improved reproductive performances in both the F × B and J × B crossbred cows.
Effects of habitat fragmentation on the genetic structure of the monophagous butterfly Polyommatus coridon along its northern range margin
Authors: Krauss Jochen , Schmitt Thomas , Seitz Alfred , Steffan‐Dewenter Ingolf , Tscharntke Teja 
Published: January 2004

AbstractPopulation genetic patterns of species at their range margin have important implications for species conservation. We performed allozyme electrophoresis of 19 loci to investigate patterns of the genetic structure of 17 populations (538 individuals) of the butterfly Polyommatus coridon, a monophagous habitat specialist with a patchy distribution. The butterfly and its larval food plant Hippocrepis comosa reach their northern distribution margin in the study region (southern Lower Saxony, Germany). Butterfly population size increased with host plant population size. The genetic differentiation between populations was low but significant (FST = 0.013). No isolation‐by‐distance was found. Hierarchical F‐statistics revealed significant differentiation between a western and an eastern subregion, separated by a river valley. The combination of genetic and ecological data sets revealed that the expected heterozygosity (mean: 18.5%) decreased with increasing distance to the nearest P. coridon population. The population size of P. coridon and the size of larval food plant population had no effect on the genetic diversity. The genetic diversity of edge populations of P. coridon was reduced compared to populations from the centre of its distribution. This might be explained by (i) an increasing habitat fragmentation towards the edge of the distribution range and/or (ii) a general reduction of genetic variability towards the northern edge of its distribution.
Tuberculous meningitis and miliary tuberculosis in young children
Authors: van den Bos F. , Terken M. , Ypma L. , Kimpen J. L. L. , Nel E. D. , Schaaf H. S. , Schoeman J. F. , Donald P. R. 
Published: February 2004

SummaryObjectives  To document the clinical and diagnostic features of tuberculous meningitis (TBM) in young children with and without concomitant miliary tuberculosis (TB).Methods  A retrospective comparative study.Results  Of 104 children with TBM, 32 (31%), median age 17.0 months, had a miliary appearance on chest radiograph; 72 (69%), median age 30.5 months, had TBM only (P = 0.04). Mediastinal adenopathy was noted in 27 (84%) of the children with miliary TB and 33 (46%) of those with TBM only (P = 0.0005). The mean cerebrospinal fluid (CSF) lymphocyte and polymorphonuclear counts of all children (no significant differences between groups) were 137 × 106/l and 38 × 106/l and the mean protein and glucose concentrations were 1.45 g/l and 0.72 mmol/l, respectively. Polymorphonuclear leukocytes were predominant in the CSF of 17% of children, in 16% the CSF glucose was >2.2 mmol/l and in 26% the CSF protein was <0.8 g/l. On Mantoux testing 37 (65%) of 57 children with TBM only and 12 (48%) of 25 children with TBM and miliary TB had an induration of ≥10 mm (P = 0.23). Ten children (10%) died, five (7%) who had TBM only and five (16%) who had TBM and miliary TB.Conclusion  Children with TBM and miliary TB were younger and more likely to have mediastinal adenopathy on chest radiography than those with TBM only. Diagnostic features and investigations in both groups may be misleading at times.
Rapid haplotype reconstruction in pedigrees with dense marker maps
Authors: Windig J. J. , Meuwissen T. H. E. 
Published: January 2004

SummaryReconstruction of marker phases is not straightforward when parents are untyped. In these cases information from other relatives has to be used. In dense marker maps, however, the space of possible haplotype configurations tends to be too large for procedures such as Monte Carlo Markov chains (MCMC) to be finished within a reasonable time. We developed an algorithm that is fast and generally finds the most probable haplotype. The basic idea is to use, the smallest informative marker brackets in offspring, for each marker interval. By using only information from the offspring and analysing each marker interval separately, the lengthy analysis of large numbers of different haplotype configurations is avoided. Nevertheless the most probable haplotype can be found quickly provided the marker map is dense and enough offspring are available. Simulations are provided to indicate how well the algorithm works at different combinations of marker density, number of offspring and number of alleles per marker. In situations where the algorithm reconstruction of the most probable haplotype is not guaranteed, the algorithm may still provide a haplotype close to the optimum, i.e. a suitable starting point for numeric optimization algorithms.
Vulnerability of Bemisia tabaci immatures to phytoseiid predators: Consequences for oviposition and influence of alternative food
Authors: Nomikou Maria , Janssen Arne , Schraag Ruud , Sabelis Maurice W. 
Published: January 2004

AbstractAn earlier study showed that two phytoseiid species, Euseius scutalis (Athias‐Henriot) and Typhlodromips swirskii (Athias‐Henriot) (Acari: Phytoseiidae), are capable of suppressing populations of Bemisia tabaci (Gennadius) (Hemiptera: Aleurodidae) on isolated cucumber plants supplied with Typha latifolia L. pollen. However, the predators did not exterminate their prey, and this may be caused by the existence of invulnerable B. tabaci stages. Little is known of the differential vulnerability of the immature B. tabaci stages. Here, we quantified their vulnerability by assessing the rate of predation on each of the immature stages when offered alone at a density high enough to allow for a maximal predation rate. All immature stages of B. tabaci were vulnerable to predation by each of the two predator species. However, the per capita predation rates, the oviposition rates of phytoseiids, as well as the percentage of predators feeding and the percentage ovipositing decreased with increasing stages of B. tabaci. Compared to that of eggs and 1st instars, the vulnerability of 2nd and later B. tabaci instars is an order of magnitude lower. To investigate how the presence of alternative food changes the rates of predation, we added pollen to a diet of 1st instars, one of the most vulnerable instars. This resulted in a decrease in the predation rate of E. scutalis, but not of T. swirskii, while the oviposition rate of both phytoseiid species remained equally high. The decreased predation of the 1st instars probably resulted from E. scutalis switching to pollen feeding.
Dissemination of the biocontrol agent Vairimorpha necatrix by the spined soldier bug, Podisus maculiventris
Authors: Down Rachel E. , Bell Howard A. , Matthews H. June , Kirkbride‐Smith Anne E. , Edwards John P. 
Published: January 2004

AbstractThe ability of the spined soldier bug, Podisus maculiventris (Say) (Heteroptera: Pentatomidae), to disseminate infective forms of two lepidopteran pathogens, Vairimorpha necatrix (Kramer) (Microspora: Microsporidia) and Lacanobia oleracea granulovirus (LoGV) was investigated. Individual female P. maculiventris that had fed on Lacanobia oleracea L. (Lepidoptera: Noctuidae) larvae, infected with V. necatrix, excreted approximately 6 × 108V. necatrix spores during the subsequent 7 days. Excreted spores were fed to L. oleracea larvae, causing 100% mortality, indicating that the spores remained viable after passing through the gut of the predator. Podisus maculiventris that had fed on V. necatrix or LoGV‐infected larvae were allowed to defecate on the foliage of tomato plants, prior to the infestation of the plants with L. oleracea or Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) larvae. This proved to be an effective way of infecting the pest larvae with the pathogens, particularly when five predatory bugs were used per plant. After 20 days, the number of S. littoralis and L. oleracea surviving on the plants was reduced by 75% and 61%, respectively. Female P. maculiventris maintained on V. necatrix‐infected prey showed reduced egg production and longevity, whilst those fed on LoGV‐infected prey showed only reduced egg production. The potential for P. maculiventris to disseminate insect pathogens is discussed in the context of improved biological control of lepidopteran pests.
Behavioural responses of the vine weevil, Otiorhynchus sulcatus, to semiochemicals from conspecifics, Otiorhynchus salicicola, and host plants
Authors: Van Tol R. W. H. M. , Visser J. H. , Sabelis M. W. 
Published: January 2004

AbstractThe vine weevil Otiorhynchus sulcatus is a parthenogenetic reproducing species which forages for suitable host plants at night, but is found congregated in dark places during the day. Frass of this weevil species is suspected to contain attractive compounds that are host‐plant related. Using a still‐air olfactometer, we tested adult vine weevils at night for their behavioural response to odours from conspecifics, feeding on a mixture of spindle tree (Euonymus fortunei) and yew (Taxus baccata), and to a sexually reproducing related species (Otiorhynchus salicicola), feeding on a mixture of ivy (Hedera helix) and cherry laurel (Prunus laurocerasus). Their attraction to conspecifics and O. salicicola appeared to be related to frass production. Freshly collected frass from O. sulcatus and from O. salicicola males and females was attractive. Prunus laurocerasus and H. helix have not been observed to be hosts of the vine weevil in the field. However, our tests showed that the vine weevil was attracted to mechanically damaged leaves of both plant species, whereas undamaged leaves were not attractive. Only undamaged young unfolding leaves of H. helix were also attractive. The attraction to odours from mechanically damaged host and non‐host plants suggested the involvement of compounds that are commonly found in many plant species. The involvement of plant compounds and/or aggregation pheromones in attraction to frass of the vine weevil and frass of the related weevil species O. salicicola is discussed.