bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhancement of fracture toughness due to energy screening effectin the early stages of non‐elastic failure
Authors: WNUK M. P. 
Published: July 2003

ABSTRACTA triaxiality‐dependent cohesive zone model for a stationary and a quasistatic crack is proposed. The model is rooted in the mesomechanical approach to Fracture Mechanics and is inspired by the quantum law concerning emission of light, which was postulated by Max Planck at the end of the 19th century. The model provides an extension of the early concepts of Barenblatt, Dugdale and the Bilby–Cotrell–Swinden team. It also incorporates the experimental observations of the pre‐fracture states due to Panin and his school in Tomsk. Relations between micro‐ and macroparameters that characterize the deformation and fracture processes in dissipative media are described in detail. The analysis suggests that the ratio of the ‘true’ work of fracture to the total energy dissipated during the course of the irreversible deformation contained within the end zone can be used as a measure of material resistance to a quasistatically propagating fracture.
Numerical investigation on J‐integral testing of heterogeneous fracture toughness testing specimens: Part I – weld metal cracks
Authors: KIM Y.‐J. , KIM J.‐S. , SCHWALBE K.‐H. , KIM Y.‐J. 
Published: July 2003

ABSTRACTBased on extensive two‐dimensional (2D) finite element (FE) analyses, the present work provides the plastic η factor solutions for fracture toughness J‐integral testing of heterogeneous specimens with weldments. Solutions cover practically interesting ranges of strength mismatch and relative weld width, and are given for three typical geometries for toughness testing: a middle cracked tension (M(T)) specimen, single edge cracked bend (SE(B)) specimen and (C(T)) specimen. For mismatched M(T) specimens, both plane strain and plane stress conditions are considered, whereas for SE(B) and C(T) specimens, only the plane strain condition is considered. For all cases, only deep cracks are considered, and an idealized butt weld configuration is considered, where the weld metal strip has a rectangular cross section. Based on the present solutions for the strength mismatch effect on plastic η factors, a window is provided, within which the homogeneous J estimation procedure can be used for weldment toughness testing. The effect of the weld groove configuration on the plastic η factor is briefly discussed, concluding the need for further systematic analysis to provide guidance to practical toughness testing.
Fatigue of cantilevered pipe fittings subjected to vibration
Authors: HAMBLIN M. 
Published: July 2003

ABSTRACTVibration fatigue failures in piping systems often occur at cantilevered small‐bore fittings (SBF) such as pressure tappings and drain valves. Piping vibration has often been assessed by measuring vibration displacement or velocity. However, in the case of straight cantilevered fittings with a concentrated mass, a better method exists. This paper presents a simple robust method of calculating vibration induced stress for cantilevered fittings at both the fitting branch neck and the main pipe. The method is based on measurement of acceleration at the concentrated mass (e.g., valve) and simple mechanics calculations. Extensive laboratory and field verification of the technique is presented. The choices of a fatigue strength criterion, such as ASME BPVC VIII Div. 2, BS7608, or a fracture mechanics approach such as BSI PD6493, are discussed. Several case studies are presented as well as simple ‘good engineering practice’ rules‐of‐thumb for SBF design. These ‘rules‐of‐thumb’ are now incorporated in the piping specifications of the author's company.
Spatial and temporal distribution of bioclimatic potential for the Codling moth and the Colorado potato beetle in Norway: model predictions versus climate and field data from the 1990s
Authors: Rafoss Trond , Sæthre May‐Guri 
Published: August 2003

Abstract 1 Based on climate data from a network of agrometeorological stations in Norway, the effects of current and future climate regimes on the spatial and temporal distribution of the Codling moth (Cydia pomonella) and the establishment potential of the Colorado potato beetle (Leptinotarsa decemlineata) were investigated.2 The study was accomplished using climex, a dynamic climate matching‐ and climate response estimation model, which predicts potential distribution of an organism based on its known geographical distribution.3 Validation of the climex model predictions for C. pomonella against field data on spatial distribution of the species in Norway resulted in a refined set of climate response parameters for C. pomonella. Temporal occurrence of C. pomonella seems to be affected by climate (temperature) and insecticide treatment against the Apple fruit moth (Argyresthia conjugella) in the previous season.4 Climate change scenarios (0.1 °C increase per degree in latitude in daily maximum and minimum temperatures) indicated an extension of the potential geographical range for C. pomonella, and 23 new locations were found favourable for its long‐term survival. The abundance and pest status of C. pomonella could increase dramatically in those locations where the species is already established.5 Leptinotarsa decemlineata would only temporarily find suitable climate conditions in Norway and hence only be able to establish interim populations in a few regions under current climate conditions. Climate change scenarios for L. decemlineata indicated that the species would be able to establish as far north as 64°N, mainly in the inland of eastern Norway.6 In general, the methods applied support the process of decreasing the uncertainty both in our knowledge about the pests themselves and about the environment, which are crucial elements in predicting whether a species is able to establish in a new area.
Effects of elevated CO2and temperature on the leaf chemistry of birchBetula pendula(Roth) and the feeding behaviour of the weevilPhyllobius maculicornis
Authors: Kuokkanen Kari , Yan Shanchun , Niemelä Pekka 
Published: August 2003

Abstract1 The effect of elevated CO2and temperature on the foliar chemistryBetula pendulaRoth and the feeding performance of polyphagous weevilsPhyllobius maculicornisGerm. was studied. Birch seedlings were grown during one growing season in chamber‐less field conditions and in closed‐top chambers exposed to four different treatments: ambient CO2(350 p.p.m) and temperature, elevated atmospheric CO2(700 p.p.m) and ambient temperature, elevated temperature +3 °C above ambient) and ambient CO2, and a combination of elevated CO2and temperature.2 In leaves under CO2enrichment, the concentration of nitrogen and some flavonol glycosides significantly decreased, whereas the concentration of total phenolics, condensed tannins and (+)‐catechin significantly increased. The total concentration of cinnamoylquinic acids was significantly increased by CO2and decreased by temperature. The concentration of salidroside increased under elevated temperature.3 Weevil‐feeding experiments were carried out in a five‐choice arrangement, one leaf from each of the five treatments (chamber‐less field controls and four different treatments in chambers) being placed in random order in a plastic box. The weevils preferred the leaves grown under elevated CO2, which had low nitrogen, high phenolics and the highest condensed tannin concentrations. Whether the reason for this trend is due to the stimulating effect of condensed tannins and/or a change in other secondary compounds, remains unknown. The weevils did not show any obviously different response in feeding performance to temperature and the combination of elevated CO2and temperature.
Detection of Rhopalosiphum insertum (apple‐grass aphid) predation by the predatory mite Anystis baccarum using molecular gut analysis
Authors: Cuthbertson Andrew G. S. , Fleming Colin C. , Murchie Archie K. 
Published: August 2003

Abstract  1 A simple, yet sensitive polymerase chain reaction based technique was developed for the detection of the apple‐grass aphid Rhopalosiphum insertum in the gut of Anystis baccarum, a predatory mite.2 A range of conserved polymerase chain reaction primers for insect mitochondrial and ribosomal DNA were tested in order to amplify R. insertum DNA. The mitochondrial DNA primers LrRNAR2 + N1F1, amplified a region between the ND1 and large subunit RNA genes.3 DNA sequencing of the R. insertum ND1‐LRNA polymerase chain reaction product allowed aphid‐specific polymerase chain reaction primers to be designed. These amplified a 283‐bp product from individual aphids. No polymerase chain reaction product was amplified from individual A. baccarum.4 Using the aphid‐specific primers against A. baccarum fed on R. insertum, the diagnostic 283‐bp product was amplified.5 Two restriction enzymes (RsaI and AluI) produced patterns that allowed unambiguous identification of R. insertum DNA from that of Macrosiphum euphorbiae and Myzus persicae.
Defoliation of Sitka spruce by the European spruce sawfly, Gilpinia hercyniae (Hartig): a retrospective analysis using the needle trace method
Authors: Williams D. T. , Straw N. A. , Day K. R. 
Published: August 2003

Abstract 1 During 1968–74, an outbreak of the European spruce sawfly Gilpinia hercyniae, defoliated many stands of Sitka spruce in commercial forests in mid‐Wales. The needle trace method was used to determine retrospectively the temporal pattern and intensity of defoliation in a stand of Sitka spruce in Hafren Forest that had been damaged severely at the time of the sawfly outbreak.2 An initial calibration experiment, designed to test the reliability of the needle trace method when applied to Sitka spruce, indicated that artificially induced defoliation of up to 75% was detected by the technique with an accuracy of ±7%. Higher rates of defoliation were underestimated by up to 17%.3 For the main sample of trees, the needle trace method demonstrated that retention of needle sets (average needle retention) was reduced by up to 33–38% over a 10‐year period coincident with the G. hercyniae outbreak and the years immediately afterward when the canopy was recovering.4 Analysis of needle loss within separate needle cohorts and age‐classes revealed that 1‐year‐old needles were the most severely defoliated. The density of 1‐year‐old needles was reduced by 51–78% in 1970–73.5 Defoliation at the time of the G. hercyniae outbreak was associated with reductions in annual height, radial, and volume increments of 24–49%, 30–59% and 32–56%, respectively. Radial and volume increments suffered their greatest reductions 1 year later than height increments.6 The study demonstrates that the needle trace method can be applied successfully to Sitka spruce to quantify defoliation caused by an insect outbreak occurring many years previously, and that the technique can provide data on needle loss that is valuable for interpreting reductions in tree growth.
Field oviposition rates and egg load dynamics of pollen beetles (Meligethes aeneus Fab.) (Colepotera: Nitidulidae)
Authors: Ekbom Barbara , Ferdinand Victoria 
Published: August 2003

Abstract 1 Egg loads from field collected pollen beetles (Meligethes aeneus Fab., Coleoptera: Nitidulidae) were determined by dissecting beetles caught at the beginning and end of the putative daily oviposition period. Field collected beetles were offered Brassica napus (L.) plants in cages for 8 (morning and early afternoon), 16 (overnight), and 24 h to ascertain the number of eggs laid during these time periods.2 Most eggs were laid in the morning and early afternoon. The proportion of gravid females was higher at the beginning of the oviposition period than at the end. Most females in the morning carried two eggs, whereas one egg was more common in the afternoon.3 We hypothesized that the number of eggs laid during the oviposition period would be equivalent to the difference between egg loads at the beginning and end of oviposition. This was not the case; differences in egg loads were significantly lower than number of eggs laid. However, the number of eggs laid was equivalent to the egg load at the beginning of the oviposition period, suggesting that eggs available in the morning are laid during the following day.4 Population estimates of daily oviposition rates, approximately 0.7 eggs per beetle and day, were close to estimates from laboratory studies when the proportion of gravid females was taken into consideration.
Feeding by the pine weevil Hylobius abietis in relation to sun exposure and distance to forest edges
Authors: Nordlander Göran , Örlander Göran , Langvall Ola 
Published: August 2003

Abstract  1 The intensity of feeding by adult pine weevils Hylobius abietis (L.) on the stem bark of Norway spruce Picea abies (L.) Karst. seedlings planted in rows with a north–south orientation across a clear‐cutting, was measured throughout a growth season. The feeding was then correlated to light interception, soil temperature and distance to the nearest forest edge.2 Feeding was at least twice as intense on seedlings in the central part of the clear‐cutting compared to those at the edges. The decline began approximatety 15 m from the edge and was of similar proportions on both the sun‐exposed and shaded sides.3 Measures of global radiation and soil temperature correlated well with consumption on the shaded side. However, on the sun‐exposed side, there were no apparent correlations with global radiation or soil temperature that could explain the decline in consumed bark area.4 We conclude that the decline in feeding towards the forest edges was mainly due to factors other than the microclimate variables we monitored. We suggest that the presence of roots of living trees along the forest edge may reduce damage to seedlings, since they provide an alternative source of food for the weevils. This alternative‐food hypothesis may also explain why seedlings in shelterwoods usually suffer less damage from pine weevils than seedlings in clear‐cuttings.
Attack dynamics of the pine shoot beetle, Tomicus piniperda (Col.; Scolytinae) in Scots pine stands defoliated by Bupalus piniaria (Lep.; Geometridae)
Authors: Cedervind Jan , Pettersson Mattias , Långström Bo 
Published: August 2003

Abstract 1 After a 1‐year, extensive pine looper (Bupalus piniaria) outbreak, plots were laid out to study tree susceptibility to attack, and performance of Tomicus piniperda in pine trees suffering from varying levels of defoliation.2 Tomicus piniperda was the dominating stem‐attacking species among the primary stem colonizers, and 82% of all trees that died had been colonized by T. piniperda.3 Beetle attacks primarily struck severely defoliated trees, i.e. trees that suffered from 90% to 100% defoliation.4 Beetle attacks peaked in the second year after cessation of the outbreak, and suppressed trees were both more frequently attacked and more susceptible to beetle attack than intermediate and dominant trees.5 Trees surviving beetle attacks carried more foliage than trees that did not survive the attacks.6 A single year of severe defoliation is enough to render pine trees susceptible to secondary pests, such as T. piniperda.
The immunological basis of psoriasis
Authors: Griffiths C E M 
Published: August 2003

ABSTRACTEvidence that psoriasis is an immune‐mediated disorder comes from laboratory studies, clinical observation, and use of targeted therapies. Immunohistochemical studies have shown that the majority of T cells in psoriatic plaques are CD45RO+ memory‐effector T cells that migrate into skin in recognition of an as yet undetermined antigen. There is also a predominance of Th1 cytokines, namely interferon gamma, in psoriatic plaques, in contrast to the predominance of Th2 cytokines found in atopic dermatitis. The efficacy of therapeutic agents that target T cells, such as anti‐CD4+ monoclonal antibodies, cyclosporin, and interleukin‐2 fusion toxin, has provided further substantial evidence that psoriasis is a T‐cell‐mediated disease. New T‐cell targeted approaches and cytokine modulation are advancing basic science in providing an understanding of the evidence for the importance of the immune process in the biology of psoriasis.
Species‐specific differences in oak foliage affect preference and performance of gypsy moth caterpillars
Authors: Foss L. K. , Rieske L. K. 
Published: July 2003

AbstractThe gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), is an introduced defoliator that preferentially feeds on oaks, Quercus spp. (Fagaceae) in the north‐eastern USA. As the gypsy moth expands its geographic range, the extensive oak component in forests and urban environments of the USA assure its successful establishment. Given their economic and ecological importance, and the gypsy moth's potential to cause mortality, we evaluated caterpillar preference and performance on various oaks prevalent in the central hardwoods region. Most of the physical and chemical characteristics we measured, from budbreak phenology to foliar chemistry, varied significantly among the oak species tested. Similarly, insect preference and performance varied significantly, though not always in predictable ways. Caterpillar preference was compared for black, Q. velutina Lamarck, burr, Q. macrocarpa Michaux, cherrybark, Q. pagoda Rafinesque, northern red, Q. rubra L., pin, Q. palustris Muenchhausen, swamp white, Q. bicolor Willdenow, white, Q. alba L., and willow, Q. phellos L., oaks. Gypsy moth preference was greatest for black and burr, and least for northern red, pin, and willow oaks. We assessed foliar characteristics and caterpillar performance on foliage from burr, cherrybark, northern red, pin, and willow oaks. Caterpillar preference did not always correlate with performance. Gypsy moth consumption and growth were highest, and development most rapid, on pin oak, which had high nitrogen and tannin levels, and was among the least preferred. Northern red and willow oaks were also among the least preferred and were the least suitable tested, producing caterpillars with moderate to low consumption and growth rates, as well as the longest development. Northern red oak contained the lowest foliar tannins; willow oak foliage was lowest in carbohydrates and nitrogen. Our results suggest that a combination of foliar characteristics may be responsible for gypsy moth preference and performance, and that an optimal combination of foliar components serves to maximize host suitability. These data will provide information useful for planning and managing urban forests in the presence of expanding gypsy moth populations.
Learning of host searching cues by the larval parasitoid Microplitis croceipes
Authors: Takasu Keiji , Lewis W.J. 
Published: July 2003

AbstractWe conducted laboratory experiments using a wind tunnel to determine the effects of prior experience on the learning and retention of learned responses in the larval parasitoid Microplitis croceipes (Cresson) (Hymenoptera: Braconidae). Although most females that had either antennated host frass or oviposited in a host in the presence of vanilla odor, made oriented flight to the odor from downwind in the wind tunnel at 30 min after experience, only those that had oviposited in a host with the odor responded to the odor at 24 h after experience. Females that had oviposited in the non‐natural host beet armyworm (BAW) larva with or without the odor did not respond to the odor at 30 min after experience. These results indicate that an oviposition in the host in the presence of odors strongly affects associative learning and the persistence of learned response to the odors. When females were allowed to antennate host frass in the presence of vanilla and to subsequently oviposit in a host within an interval of 5 min or less, their learned response to vanilla also persisted for 24 h. Similarly, when females were conditioned to link vanilla with host frass and then allowed to make an ovipositor contact with host hemolymph, their learned response persisted for 24 h. However, antennal contact with hemolymph after such conditioning of vanilla with host frass did not improve the persistence of learned response to the odor. These results indicate that ovipositor contact with host hemolymph during oviposition is partially responsible for an increased retention of learned response. Females responded to vanilla 48% of the time at 30 min after antennating host frass without the odor, but their response to the odor significantly decreased after oviposition in a BAW larva subsequent to the antennation of host frass. This result indicates that oviposition in a BAW larva decreases subsequent response to general odors. Based on the results, we discuss the foraging behavior of M. croceipes dependent on learning and subsequent experiences.
The effects of host weight at parasitism on fitness correlates of the gregarious koinobiont parasitoid Microplitis tristis and consequences for food consumption by its host, Hadena bicruris
Authors: Elzinga Jelmer A. , Harvey Jeffrey A. , Biere Arjen 
Published: July 2003

AbstractGregarious koinobiont parasitoids attacking a range of host sizes have evolved several mechanisms to adapt to variable host resources, including the regulation of host growth, flexibility in larval development rate, and adjustment of clutch size. We investigated whether the first two mechanisms are involved in responses of the specialist gregarious parasitoid Microplitis tristis Nees (Hymenoptera: Braconidae) to differences in the larval weight and parasitoid load of its host Hadena bicruris Hufn. (Lepidoptera: Noctuidae). In addition, we examined the effects of parasitism on food consumption by the host. Parasitoids were offered caterpillars of different weight from all five instars, and parasitoid fitness correlates, including survival, development time, and cocoon weight, were recorded. Furthermore, several host growth parameters and food consumption of parasitized and unparasitized hosts were measured. Our results show that M. tristis responds to different host weights by regulating host growth and by adjusting larval development rate. In hosts with small weights, development time was increased, but the increase was insufficient to prevent a reduction in cocoon weight, and as a result parasitoids experienced a lower chance of successful eclosion. Cocoon weight was negatively affected by parasitoid load, even though host growth was positively affected by parasitoid load, especially in hosts with small weights. Later instars were more optimal for growth and development of M. tristis than early instars, which might reflect an adaptation to the life‐history of the host, whose early instars are usually concealed and inaccessible for parasitism on its food plant, Silene latifolia Krause (Caryophyllaceae). Parasitism by M. tristis greatly reduced total host food consumption for all instar stages. Whether plants can benefit directly from the attraction of gregarious koinobiont parasitoids of their herbivores is a subject of current debate. Our results indicate that, in this system, the attraction of a gregarious koinobiont parasitoid can directly benefit the plant by reducing the number of seeds destroyed by the herbivore.
Marking bark beetle parasitoids within the host plant with rubidium for dispersal studies
Authors: Hougardy E. , Pernet P. , Warnau M. , Delisle J. , Grégoire J.‐C. 
Published: July 2003

AbstractA technique using rubidium chloride (RbCl), a trace element, as internal label is proposed for marking hymenopteran parasitoids attacking a concealed host, Ips typographus L. (Coleoptera: Scolytidae). RbCl was introduced directly into spruce via the vascular system using glass tubing. RbCl passed through the food chain and was detected at the parasitoid level by electrothermal atomic absorption spectroscopy (EAAS) or flame emission spectroscopy (FES). Mark persistency until day 8 after emergence was tested in labelled Rhopalicus tutela (Walker) (Hymenoptera: Pteromalidae). The mark decreased with time only in fed females, probably due to excretion and/or egg resorption. The proportion of marked males did not vary with time or treatment.