bluuebunny/crossref_metadata_2025 huggingface dataset:
FATIGUE LIFE OF AN AUTOFRETTAGED THICK‐WALLED PRESSURE VESSEL WITH AN EXTERNAL GROOVE
Authors: Koh S. K.
Published: August 2010

Abstract— Fatigue tests that simulate an autofrettaged thick‐walled pressure vessel with an external groove under pulsating internal pressure loading conditions were performed using specimens taken from an autofrettaged thick‐walled pressure vessel. Load‐controlled simulation fatigue tests using rectangular, elliptic, and shot peened elliptic grooved specimens were performed for three different autofrettage levels of 50, 75, and 100% overstrains. In order to estimate the fatigue life of the thick‐walled pressure vessel subjected to pulsating internal pressure, the local strain approach was considered to assess the crack formation life. A cyclic stress‐strain relation and fatigue damage models determined from strain‐controlled low cycle fatigue tests were employed to estimate the fatigue life of the autofrettaged thick‐walled pressure vessel. Larger local stresses and strains were obtained from the Neuber's rule compared to the linear rule and these led to conservative fatigue life estimations. Estimated fatigue lives were obtained within factors of 2 to 4, compared to the experimental fatigue lives determined from the simulation fatigue tests.
CRACK EXTENSION UNDER MIXED‐MODE LOADING IN AN ANISOTROPIC MODE–ASYMMETRIC MATERIAL IN RESPECT OF RESISTANCE TO FRACTURE
Authors: Kfouri A. P.
Published: August 2010

Abstract— Recently, a crack path fracture criterion was proposed by Kfouri and Brown, based on maximum energy release rates at the tip of short kinks emanating from an existing crack when the main crack is subjected to mixed‐mode loading. Assuming a ‘mode asymmetry’ in respect of the fracture resistances of the material, KIr, and KIIr, for pure mode I and pure mode II, respectively, i.e., KIIr, differing from KIr, generally, the modified criterion proposed that the resistance to fracture is a function of the ratio q (=k2/k1) of the mode II to the mode I stress intensity factors at the tip of the kink.

The aim of the present paper is to extend the modified criterion by presenting it in a form that takes into account material fracture resistance anisotropy in addition to the fracture resistance mode asymmetry previously described. Note however that the material's elastic properties are still assumed to be isotropic. A short FORTRAN computer program has been written to predict the kink angle under mixed‐mode loading for cracks in materials with mode asymmetry and material anisotropy with respect to their fracture resistance properties, and the inclination angle, θ, defining the direction of the main crack in the material. The values of four parameters, r0, r90, s and θ, described in the text, characterising the material fracture resistance asymmetrical and anisotropic properties and the orientation of the main crack, are prompted by the program, which provides, almost instantaneously, the kink angles under various loading modes and much additional relevant information. The effects of the variation of these parameters, treated singly or in combination, and the discontinuous “catastrophic” character of many of the responses at certain “transition” values of the parameters, are illustrated further. In the discussion it is recognised that the translation of the results of the analysis of a highly idealised situation to actual practical problems on real materials encountered in practice, is not straightforward but, notwithstanding, since material fracture resistance anisotropy and fracture resistance mode asymmetry may well be present in the real world, the possible influence of these factors perhaps needs to be taken into account in studies on crack paths.
CRACK GROWTH ARRESTING PROPERTY OF A HOLE AND BRINELL‐TYPE DIMPLE
Authors: Goto M. , Miyagawa H. , Nisitani H.
Published: August 2010

Abstract— Fatigue tests of sheet specimens having a central crack were carried out to study the effects of holes and dimples on the arrest of fatigue crack propagation. Two holes were drilled at some distance from, and at either side of, a crack tip, and the dimple of a certain diameter was introduced by pressing steel balls in the specimen at a crack tip. Results showed that the two holes produced an increase in crack propagation life (about 3 times) when the holes were drilled at an appropriate distance. On the other hand, the effect of a dimple on the fatigue strength was remarkably large, i.e. in the greatest case a 2.2 times increase in the fatigue endurance limit of cracked specimens and about a 50 times increase in the crack propagation life, at stresses above the fatigue limit. The main reason for the remarkable recovery of fatigue strength was the residual compressive stresses produced by the dimple. To evaluate the effect of residual compressive stresses on the da/dN vs. δK relation, a simple model is proposed. By using this model, the effect of residual stresses on crack propagation can be estimated quantitatively. Furthermore, the fatigue life of dimpled specimens was estimated based on the model.
THE INFLUENCE OF TWO‐STAGE LOADING ON THE LONGITUDINAL SPLITTING OF UNIDIRECTIONAL CARBON/EPOXY LAMINATES
Authors: Found M. S. , Kanyanga S. B.
Published: August 2010

Abstract— A review of variable fatigue loading of carbon fibre/epoxy laminates indicates that for two‐stage loading, low‐to‐high loading is generally more damaging than high‐to‐low loading. Damage accumulation under two‐stage loading appears to produce linear damage in some CFRP materials and non‐linear behaviour in others. The behaviour of those materials exhibiting linear damage may be predicted by the Palmgren‐Miner rule. A model is presented for determining the longitudinal split growth in notched unidirectional carbon fibre/epoxy test coupons. The model is able to predict the non‐linear split growth for low‐to‐high loading whilst the linear damage accumulation for high‐to‐low loading may best be determined by use of the Palmgren‐Miner rule.
EFFECTS OF SURFACE TREATMENTS ON THE FATIGUE OF NOTCHED BEND SPECIMENS
Authors: Fereira J. A. M. , Borrego L. F. P. , Costa J. D. M.
Published: August 2010

Abstract— This paper presents results of a fatigue life investigation carried out on notched bend specimens with square section and surface semi‐circular notches. The material of the specimens was A515 Grade 70 steel. The series of tests were carried out: (i) on specimens without treatment, (ii) on shot peened specimens and (iii) on PVD coated specimens. The stress concentration factors were computed by the finite element method. The crack initiation life was predicted using the equivalent strain energy density and Neuber's rule methods, associated with Morrow's equation. Good agreement was observed between experimental and predicted results. A considerable improvement in the fatigue crack initiation lives was achieved on the shot peened specimens and on the PVD coated specimens in comparison with non‐treated specimens.
THE EFFECT OF MICROSTRUCTURE ON FRACTURE TOUGHNESS OF POLYCRYSTALLINE ALUMINA
Authors: Nicoletto G. , Tucci A. , Esposito L.
Published: August 2010

Abstract— A study of the dependence of the fracture toughness on the microstructural morphology of polycrystalline materials is presented. The microstructure of several aluminas was characterized by thermal etching and image analysis. The fracture toughness of these materials was then determined by bridge‐indentation pre‐cracking followed by a four‐point bending test procedure. A SEM investigation of the mechanisms of crack propagation was also carried out. The observed microstructure‐related fracture toughness responses are discussed.
ELLIPTICAL SUBSURFACE CRACKS UNDER A NORMAL STRESS AND A RESIDUAL STRESS FIELD
Authors: Fischer F. D. , Mayrhofer K. , Parteder E.
Published: August 2010

Abstract The distribution of residual stresses due to surface treatments, such as nitriding, induction hardening or shot‐peening, is explained in the introduction. The stress intensity factor distribution along an elliptical plane crack near the surface in such a residual field is presented. Existing methods including the weight function method do not allow one to find this distribution directly. Therefore, a finite element study was undertaken showing the complex character of the stress intensity factor distribution. Additionally, the calculation of the stress intensity factor distribution around the crack front for an external tension or bending load stress is explained. In these cases some simplified semi‐analytical expressions can be found.
Fracture analysis of composite co‐cured structural joints using decohesion elements
Authors: CAMANHO P. P. , DÁVILA C. G. , PINHO S. T.
Published: August 2010

Delamination is one of the predominant forms of failure in laminated composite structures, especially when there is no reinforcement in the thickness direction. To develop composite structures that are more damage tolerant, it is necessary to understand how delamination develops, and how it can affect the residual performance. A number of factors such as residual thermal stresses, matrix‐curing shrinkage and manufacturing defects affect how damage will grow in a composite structure. It is important to develop computationally efficient analysis methods that can account for all such factors. The objective of the current work is to apply a newly developed decohesion element to investigate the debond strength of skin‐stiffener composite specimens. The process of initiation of delaminations and the propagation of delamination fronts is investigated. The numerical predictions are compared with published experimental results.
Comparative analysis of fatigue life predictions in central notched specimens of Al–Mg–Si alloys
Authors: COSTA J. D. M. , ANTUNES F. J. V. , SILVA V. R. , FERREIRA J. A. M.
Published: August 2010

The fatigue behaviour of an Al–Mg–Si alloy was studied using notched specimens. Fatigue tests were conducted at two stress ratios R= 0 and R= 0.4 on thin plates with a central hole. Constant and block variable loading amplitudes were applied to the specimens using a servo‐hydraulic machine. The applicability of the local strain approach method to the prediction of the fatigue life was investigated for this type of discontinuity. Two methods, the equivalent strain energy density approach and a modified stress–strain intensity field approach, were used to predict the fatigue strength. For the second one an elastic–plastic finite element analysis was carried out in order to obtain the local strain and stress distributions near the notch root. Based on Miner's rule an equivalent stress was used to correlate the fatigue lives for the variable amplitude histories. The experimental results were compared with the predicted results obtained by the two methods investigated and better agreement was found with the stress–strain field intensity approach, while the strain energy approach gave more conservative results. Miner's rule gives a good correlation between the variable amplitude and constant amplitude results.
Influence of intralaminar cracking on the apparent interlaminar mode I fracture toughness of cross‐ply laminates
Authors: De MOURA M. F. S. F. , PEREIRA A. B. , De MORAIS A. B.
Published: August 2010

One of the major difficulties in interlaminar fracture tests of multidirectional laminates is the high tendency for intralaminar cracking and the resulting wavy crack propagation. Experimental work showed that this occurred in double cantilever beam (DCB) tests of cross‐ply laminates having a starter crack on a 0°/90° interface. Moreover, under steady‐state propagation conditions, the apparent values of the critical strain energy release rate GIc were two times higher than those of 0°/0° specimens. In this paper, a finite‐element‐based progressive damage model was used to simulate crack propagation in cross‐ply specimens. The results showed that transverse cracking alone cannot be responsible for the above difference of GIc values. Therefore, the higher propagation GIc values for cross‐plies must be attributed to the more extensive fibre bridging observed and to plastic deformations of the 90° interfacial ply.
Elevated temperature fatigue crack growth in directionally solidified GTD‐111 superalloy
Authors: HIGHSMITH S. , JOHNSON W. S.
Published: August 2010

GTD‐111 is a General Electric proprietary nickel‐base superalloy widely employed in a growing fleet of industrial gas turbines. However, much of the published research to date has focused on creep damage and coating durability, with no available data on fatigue crack growth rate (FCGR). Accordingly, FCGR has been measured at several load ratios and an elevated temperature, 760 °C (1400 °F) corresponding to typical turbine bucket conditions. In order to account for load ratio effect, several different methods for determining Walker model parameters are discussed in terms of methodological consistency and accuracy.
A comparison of total fatigue life models for composite laminates
Authors: CHEN H. , SHIVAKUMAR K. , ABALI F.
Published: August 2010

A total fatigue life model proposed previously by the same authors for laminated composite structures subjected to mode‐I fracture loading is evaluated by two newer models. The new models differ from the original model by normalization factor and approximation of stable delamination growth rate equation. All three models include the delamination growth in subcritical (delamination initiation), linear (stable growth) and final (unstable growth) fracture domains. All three models were evaluated by comparing the total life predictions for two different block loadings. One is a normal operation of a rotor craft‐type structure and the other is an aggressive loading. Predicted results of the three models were compared with each other and with the experimental data. The material considered was woven‐roving E‐glass fibre and vinyl ester matrix and the laminate was made by vacuum assisted resin transfer molding.
Effect of mean stress on fretting fatigue of Ti‐6Al‐4V on Ti‐6Al‐4V
Authors: LOVRICH N. R. , NEU R. W.
Published: August 2010

Fretting fatigue tests of Ti‐6Al‐4V on Ti‐6Al‐4V have been conducted to determine the influence of stress amplitude and mean stress on life. The stress ratio was varied from R=−1 to 0.8. Both flat and cylindrical contacts were studied using a bridge‐type fretting fatigue test apparatus operating either in the partial slip or mixed fretting regimes. The fretting fatigue lives were correlated to a Walker equivalent stress relation. The influence of mean stress on fretting fatigue crack initiation, characterized by the value of the Walker exponent, is smaller compared with plain fatigue. The fretting fatigue knockdown factor based on the Walker equivalent stress is 4. Formation of fretting cracks is primarily associated with the tangential force amplitude at the contact interface. A simple fretting fatigue crack initiation metric that is based on the strength of the singular stress field at the edge of contact is evaluated. The metric has the advantage in that it is neither dependent on the coefficient of friction nor the location of the stick/slip boundary, both of which are often difficult to define with certainty a priori.
Elastic T stress estimates for circumferential surface‐cracked cylinders*
Authors: HUH N.‐S.
Published: August 2010

On the basis of detailed three‐dimensional (3D) elastic finite element (FE) analyses, this paper provides tractable approximations for elastic T stress solutions for circumferential inner‐surface cracks in cylinders. Internal pressure and global bending moment were considered. The FE model and analysis procedure employed in the analysis were verified using existing solutions for both elastic stress intensity factor and T stress. To cover a practical range, three different values of the ratio of the mean radius of cylinder to the thickness, Rm/t, were selected; furthermore, four different values of the ratio of the crack depth to the thickness, a/t, ranging from 0.1 to 0.75 and three different values of θ/π ranging from 0.1 to 0.4 were selected. On the basis of FE analyses results, polynomial approximations were proposed at three different locations: surface point, middle point and deepest point. On the basis of the detailed 3D elastic FE analysis, the solutions presented are believed to be the most accurate, and thus provide valuable information for structural integrity assessment considering a crack‐tip constraint.
Latent crack path and service life predictions for unnotched concrete under bending by digital speckle correlation method
Authors: GUO LI‐PING , SUN WEI , CARPINTERI ANDREA
Published: August 2010

The critical factor for flexural fracture of an unnotched concrete structure is the local damage with stress concentration. The latent critical crack path on the concrete surface is difficult to inspect using ordinary experimental methods. In the present paper, the digital speckle correlation method (DSCM) is employed to obtain the latent critical crack and to calculate the strain and displacement distributions on the surface of unnotched concrete under flexural load. The relationships of static flexural load versus longitudinal strain and load‐direction displacement as well as fracture toughness are inherent material parameters. Furthermore, the cohesive energy density (CED) around the latent critical crack for unnotched concrete and the brittleness number are also determined by using the DSCM results. Then, the tensile performance of concrete and the residual service life are evaluated through the above material parameters. It is found that the latent crack path on the concrete surface depends on the strain fields after the bending force applied to the specimen reaches 30% of concrete flexural strength, and the cohesive stress does not rapidly increase until reaching 75% of concrete flexural strength. The service life of unnotched concrete without steel bars is dependent on the local cohesive performance around the latent crack path. Finally, the experimental results show that DSCM is useful to confirm the connection between the local damage of the material and the whole structure safety.
Fatigue crack propagation in tensile shear stainless steel spot welded specimens
Authors: LANCIOTTI A. , POLESE C.
Published: August 2010

Fatigue tests were carried out on 4 mm thick spot welded joints; the material was stainless steel AISI 301, quarter hard. Some specimens were instrumented with a strain gauge bonded in correspondence with one of the edges of the spot weld. Strain gauge output was demonstrated to be a reliable instrument to monitor the nucleation and propagation of fatigue cracks. A good correlation was found between strain gauge output and spent fatigue life. Some fatigue tests were suspended when the strain gauge output was equal to pre‐fixed values, corresponding to fatigue life in the range from 15 to 85%. Subsequently, the specimens were dissected to observe fatigue cracks. The same correlation existed between crack depth and fatigue life. Small cracks were observed in specimens fatigue tested up to 15% of the mean fatigue life; fatigue cracks in the joints under examination would be nucleated between 5 and 10% of fatigue life.

Finite Element calculations were carried out, introducing in the models cracks similar to those observed in the fatigue tests. Calculated strain at the external surface compared well with the measured strain as a function of crack depth. Calculations demonstrated that small errors in strain gauge position can be tolerated without appreciable deterioration in crack dimension prediction.
Fatigue crack growth through a residual stress field introduced by plastic beam bending
Authors: JONES K. W. , DUNN M. L.
Published: August 2010

We present predictions and measurements of fatigue crack growth rates in plastically bent aluminium 2024‐T351 beams. Beam bending and fatigue were carefully controlled to minimize factors other than residual stress that could affect the fatigue crack growth rate, such as large plastic strains or residual stress relaxation. The residual stress introduced by bending was characterized by a bending method and by the slitting method, with excellent agreement between the two methods. Crack growth rates were predicted by three linear elastic fracture mechanics (LEFM) superposition based methods and compared to experimental measurements. The prediction that included the effects of partial crack closure correlated with experimental data to within the variability normally observed in fatigue crack growth rate testing of nominally residual stress free material. Therefore, we conclude that crack growth through residual stress fields may be predicted using the concept of superposition as accurately as crack growth through residual stress free material, provided that the residual stress is accurately known, the residual stress remains stable during fatigue, the material properties are not changed by the introduction of residual stress, and that the effect, if any, of partial crack closure is taken into account.
Fatigue life assessment for brake disc of railway vehicle
Authors: KIM D.‐J. , SEOK C.‐S. , KOO J.‐M. , WE W.‐T. , GOO B.‐C. , WON J.‐I.
Published: August 2010

The brake disc of a railway should have stability. After long‐term use, the brake disc may be seriously damaged by thermal fatigue cracks on the frictional surface. In this study, fatigue tests were carried out for a brake disc material (GC25). Furthermore, in order to determine the cause of the thermal fatigue cracks, contact pressure and thermal stress analyses were performed. From these results, the linear relation between temperature and stress variations was obtained, and the remaining life assessment of the brake disc of a railway vehicle was performed by using it.
Adenosine drives recycled vesicles to a slow‐release pool at the mouse neuromuscular junction
Authors: Perissinotti Paula P. , Uchitel Osvaldo D.
Published: August 2010

The effects of adenosine on neurotransmission have been widely studied by monitoring transmitter release. However, the effects of adenosine on vesicle recycling are still unknown. We used fluorescence microscopy of FM2‐10‐labeled synaptic vesicles in combination with intracellular recordings to examine whether adenosine regulates vesicle recycling during high‐frequency stimulation at mouse neuromuscular junctions. The A1adenosine receptor antagonist (8‐cyclopentyl‐1,3‐dipropylxanthine) increased the quantal content released during the first endplate potential, suggesting that vesicle exocytosis can be restricted by endogenous adenosine, which accordingly decreases the size of the recycling vesicle pool. Staining protocols designed to label specific vesicle pools that differ in their kinetics of release showed that all vesicles retrieved in the presence of 8‐cyclopentyl‐1,3‐dipropylxanthine were recycled towards the fast‐release pool, favoring its loading with FM2‐10 and suggesting that endogenous adenosine promotes vesicle recycling towards the slow‐release pool. In accordance with this effect, exogenous applied adenosine prevented the replenishment of the fast‐release vesicle pool and, thus, hindered its loading with the dye. We had found that, during high‐frequency stimulation, Ca2+influx through L‐type channels directs newly formed vesicles to a fast‐release pool (Perissinottiet al., 2008). We demonstrated that adenosine did not prevent the effect of the L‐type blocker on transmitter release. Therefore, activation of the A1receptor promotes vesicle recycling towards the slow‐release pool without a direct effect on the L‐type channel. Further studies are necessary to elucidate the molecular mechanisms involved in the regulation of vesicle recycling by adenosine.
Src family kinases mediate the inhibition of substance P release in the rat spinal cord by μ‐opioid receptors and GABABreceptors, but not α2adrenergic receptors
Authors: Zhang Guohua , Chen Wenling , Marvizón Juan Carlos G.
Published: August 2010

GABAB, μ‐opioid and adrenergic α2receptors inhibit substance P release from primary afferent terminals in the dorsal horn. Studies in cell expression systems suggest that μ‐opioid and GABABreceptors inhibit transmitter release from primary afferents by activating Src family kinases (SFKs), which then phosphorylate and inhibit voltage‐gated calcium channels. This study investigated whether SFKs mediate the inhibition of substance P release by these three receptors. Substance P release was measured as neurokinin 1 receptor (NK1R) internalization in spinal cord slices andin vivo. In slices, NK1R internalization induced by high‐frequency dorsal root stimulation was inhibited by the μ‐opioid agonist DAMGO and the GABABagonist baclofen. This inhibition was reversed by the SFK inhibitor PP1. NK1R internalization induced by low‐frequency stimulation was also inhibited by DAMGO, but PP1 did not reverse this effect.In vivo, NK1R internalization induced by noxious mechanical stimulation of the hind paw was inhibited by intrathecal DAMGO and baclofen. This inhibition was reversed by intrathecal PP1, but not by the inactive PP1 analog PP3. PP1 produced no effect by itself. The α2adrenergic agonists medetomidine and guanfacine produced a small but statistically significant inhibition of NK1R internalization induced by low‐frequency dorsal root stimulation. PP1 did not reverse the inhibition by guanfacine. These results show that SFKs mediate the inhibition of substance P release by μ‐opioid and GABABreceptors, but not by α2receptors, which is probably mediated by the binding of G protein βγ subunits to calcium channels.
Eccentric exercise induces chronic alterations in musculoskeletal nociception in the rat
Authors: Alvarez Pedro , Levine Jon D. , Green Paul G.
Published: August 2010

Eccentric muscle exercise is a common cause of acute and chronic (lasting days to weeks) musculoskeletal pain. To evaluate the mechanisms involved, we have employed a model in the rat, in which eccentric hind limb exercise produces both acute mechanical hyperalgesia as well as long‐term changes characterized by enhanced hyperalgesia to subsequent exposure to an inflammatory mediator. Eccentric exercise of the hind limb produced mechanical hyperalgesia, measured in the gastrocnemius muscle, which returned to baseline at 120 h post‐exercise. When nociceptive thresholds had returned to baseline, intramuscular injection of prostaglandin E2 (PGE2) induced hyperalgesia that was unattenuated 240 h later, much longer than PGE2‐induced hyperalgesia in unexercised rats (4 h). This marked prolongation of PGE2 hyperalgesia induced by eccentric exercise was prevented by the spinal intrathecal injection of oligodeoxynucleotide antisense to protein kinase Cε, a second messenger in nociceptors implicated in the induction of chronic pain. Exercise‐induced hyperalgesia and prolongation of PGE2 hyperalgesia were inhibited by the spinal intrathecal administration of antisense for the interleukin‐6 but not the tumor necrosis factor α type 1 receptor. These findings provide further insight into the mechanism underlying exercise‐induced chronic muscle pain, and suggest novel approaches for the prevention and treatment of exercise‐ or work‐related chronic musculoskeletal pain syndromes.
Autaptic cultures of single hippocampal granule cells of mice and rats
Authors: Rost Benjamin R. , Breustedt Jörg , Schoenherr Anke , Grosse Gisela , Ahnert‐Hilger Gudrun , Schmitz Dietmar
Published: August 2010

When a single neuron is grown on a small island of glial cells, the neuron forms synapses onto itself. The so‐called autaptic culture systems have proven extremely valuable in elucidating basic mechanisms of synaptic transmission, as they allow application of technical approaches that cannot be used in slice preparations. However, this method has been almost exclusively used for pyramidal cells and interneurons. In this study, we generated autaptic cultures from granule cells isolated from the dentate gyrus of rodent hippocampi. Our subsequent morphological and functional characterisation of these cells confirms that this culture model is suitable for investigating basic mechanisms of granule cell synaptic transmission. Importantly, the autosynaptic connectivity allows recordings of pure mossy fibre miniature EPSCs, which are not possible in slice preparations. Further, by fast application of hypertonic sucrose solutions it is possible to directly measure the readily releasable pool and to calculate the probability of vesicular release.
Are parasites ‘‘prudent’’ in space?
Authors: Lion Sébastien , Boots Mike
Published: August 2010

Ecology Letters(2010)

There has been a renewed controversy on the processes that determine evolution in spatially structured populations. Recent theoretical and empirical studies have suggested that parasites should be expected to be more ‘‘prudent’’ (less harmful and slower transmitting) when infection occurs locally. Using a novel approach based on spatial moment equations, we show that the evolution of parasites in spatially structured host populations is determined by the interplay of genetic and demographic spatial structuring, which in turn depends on the details of the ecological dynamics. This allows a detailed understanding of the roles of epidemiology, demography and network topology. Demographic turnover is needed for local interactions to select for prudence in the susceptible‐infected models that have been the focus of previous studies. In diseases with little demographic turnover (as typical of many human diseases), we show that only parasites causing diseases with long‐lived immunity are likely to be prudent in space. We further demonstrate why, at intermediate parasite dispersal, virulence can evolve to higher levels than predicted by non‐spatial theory.
Control of Black Vine Weevil larvae Otiorhynchus sulcatus (Fabricius) (Coleoptera:Curculionidae) in grow bags outdoors with nematodes
Authors: Lola‐Luz Theodora , Downes Martin , Dunne Richard
Published: August 2010

Abstract  1 Outdoor trials were carried out during 2001–02 on strawberries grown in commercial growing bags naturally infested with black vine weevil larvae (BVW) Otiorhynchus sulcatus in Co. Wexford, Ireland.

2 The two nematode isolates used in these trials were Heterorhabditis megidis (UK211) and Heterorhabditis downesi (K122), both laboratory cultured. Growing bags received nematodes either once (May 2001), twice (May and October 2001) or three times (May, October 2001 and May 2002). Ten days after each application date, nine blocks (of the total 27) were randomly selected, destructively assessed and discarded.

3 The single application (May 2001) resulted in a mortality of black vine weevil larvae, of 93.4% with H. megidis and 51.3% with H. downesi, compared with the control treatment at that date. Respective figures after the double application (May 2001 and October 2001) were 78.9 and 77.6% and after the triple application (May 2001, October 2001 and May 2002) the figures were 93.7 and 88.1%.

4 Results from these trials clearly indicate that entomopathogenic nematodes are good alternatives to chemical control of the black vine weevil on strawberries grown in growing bags in Ireland.
Effects of green tree retention, prescribed burning and soil treatment on pine weevil (Hylobius abietis and Hylobius pinastri) damage to planted Scots pine seedlings
Authors: Pitkänen A. , Törmänen K. , Kouki J. , Järvinen E. , Viiri H.
Published: August 2010

1 Feeding damage and mortality caused to planted Scots pine seedlings by the pine weevils Hylobius abietis and Hylobius pinastri were studied on burned and unburned sites with 0, 10 and 50 m3 per hectare levels of green tree retention from the second to the fourth summer after logging and burning of the sites.

2 The rate of severe feeding damage to pine seedlings caused by pine weevils was higher on burned clearcut sites than on unburned ones, whereas burning did not increase the feeding damage rate on sites with groups of retention trees. The damage rate in the fourth summer was approximately the same on burned and unburned sites.

3 Pine weevil feeding was the major cause of mortality of freshly planted pine seedlings on unburned sites. On burned sites, mortality was higher than the rate of severe feeding damage, particularly in the second summer after burning, possibly owing to fungal attack and abiotic factors.

4 At a retention tree level of 50 m3, feeding damage to the seedlings was lower than on clearcuts and at a 10 m3 retention tree level. Furthermore, on sites with 50 m3 of retention trees, scarification of the soil was found to decrease feeding damage more effectively than on clearcuts and 10 m3 sites. If the seedlings were situated in the centre of scarified patches, scarification alone was as effective as insecticide treatment on unscarified soil for decreasing feeding damage and mortality.

5 The results suggest that when burning is applied as silvicultural treatment after clear‐cuts, retention of trees is recommended to reduce the damages caused by pine weevils on pine seedlings.
Insect‐screened cultivation to reduce the invasion of tomato crops by Bemisia tabaci: modelling the impact on virus disease and vector
Authors: Holt J. , Pavis C. , Marquier M. , Chancellor T. C. B. , Urbino C. , Boissot N.
Published: August 2010

1 In two experiments carried out in Guadeloupe, barriers were used to reduce the entry of the virus vector Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) to tomato plots. The barriers erected around the crop were of insect‐proof cloth fences (<50 mesh), 1.5 m in height, in the first experiment with a deltamethrin‐treated, insect‐attracting strip facing inwards, and, in the second, with the barrier but no insecticide‐treated strip.

2 A mathematical model of epidemic development was fitted to the symptom data from the treated and control (unprotected) tomato plots. There were two viruses present, tomato yellow leaf curl and potato yellow mosaic; specific detection confirmed that symptoms gave an accurate indication of infection and that the two virus diseases had similar progress curves.

3 Parameter estimates obtained by model‐fitting suggested that the barriers reduced vector immigration by approximately 12‐fold but that B. tabaci retention within the plots was also increased slightly despite the mortality caused by the insecticide‐treated strips. Disease establishment was delayed by approximately 2 weeks. The results obtained in the second experiment involving barriers deployed without insecticide‐treated strips could be explained by a large increase in B. tabaci retention within the barriers resulting in more rapid virus disease progress than in controls. The results of mathematical modelling indicate that partial insect barriers can be worse than none because sufficient whiteflies can enter to establish a population and, at the same time, large numbers are retained in the barrier plot, with the net effect being a more rapid population increase than in the absence of barriers.
Stable isotopes analysis to assess the trophic role of ants in a Mediterranean agroecosystem
Authors: Ottonetti Lorenzo , Tucci Lorenzo , Chelazzi Guido , Santini Giacomo
Published: August 2010

1 Stable isotopes signatures (δ13C and δ15N) of the most important tree‐dwelling ants in an olive orchard were examined, together with the signatures of the most common herbivores, predators and sap‐sucking insects. The olive orchard consists of separate subunits (trees) surrounded by a matrix of grasses or bare ground, and the role of ants in such a system is not fully understood.

2 None of the selected ant species was exclusive to the olive trees because they were also observed foraging on vegetation (mainly thistle) under the tree crowns. Hence, the relative contributions of these two sources of energy (olive trees versus herbs/grasses) were assessed by comparing the δ13C of ants with the signatures of plants and those of other arthropods collected on the trees and on nearby thistles. Next, the trophic level occupied by the ants and their ecological role within the olive food web were determined by examining the δ15N values and their relationship with indices of ecological performance measuring the potential pressure exerted by each species on the ecosystem.

3 The analysis of13C signatures revealed a different contribution of the two energy sources, olive trees versus herbs and grasses, with the former being more important for ants. The analysis of15N signatures suggested separate roles for different ant species: some (Crematogaster scutellaris,Lasius lasioides) occupied a higher trophic level, mostly involved in predation, whereas others (Camponotus piceus,Camponotus lateralis) occupied a lower level, probably involved more in homopteran tending. A fifth species (Camponotus aethiops) was in an intermediate position. Finally, the δ15N levels of the species were significantly correlated with indices of ecological performance.
Mutual benefit interactions between banded pine weevilPissodes castaneusand blue‐stain fungusLeptographium serpensin maritime pine
Authors: Pestaña Montserrat , Santolamazza‐Carbone Serena
Published: August 2010

Ecological interactions between banded pine weevilPissodes castaneusand blue‐stain fungusLeptographium serpens, when simultaneously sharing the same host plant (maritime pinePinus pinaster) in winter and spring, were investigated. Temporal components of the interaction were taken into account by either introducing the weevils and the pathogen simultaneously or sequentially, with the weevils being introduced 1 month after the fungal inoculation.

We measured larval mortality, development time, offspring number, sex ratio and body size ofP. castaneus. Phloem phosphorus and nitrogen concentrations were also assessed. Furthermore, we tested whether: (i) emerging offspring transported propagules of the fungus; (ii) artificially‐contaminated weevils may transmit the disease to healthy trees; and (iii) field collectedP. castaneuscarry the fungus.

The fungus enhanced weevil colonization and brood production in both seasons. During winter and spring, adults from trees where the pathogen was inoculated prior to weevil introduction emerged earlier than weevils from trees where they had been introduced simultaneously with the fungus. During winter, weevils from pre‐inoculated trees were also larger. Sex ratio and larval mortality were not affected.Leptographium serpensdid not affect phloem nitrogen content but phosphorus content was greater in plants inoculated with the pathogen, which may explain the findings on weevil growth.

Sixty‐five percent of the weevils that emerged from inoculated trees carried spores ofL. serpens, although no successful isolation was made from field collected weevils. The fungus was recovered from 25% of the trees infested with artificially‐contaminated weevils.

These results suggest thatP. castaneusbenefits from the presence ofL. serpensand may contribute to its spread.
Limitations of metformin use in patients with kidney disease: are they warranted?
Authors: Vasisht K. P. , Chen S.‐C. , Peng Y. , Bakris G. L.
Published: August 2010

Aim: To show that metformin, one of the most widely used agents, is contraindicated in patients with diabetes having chronic kidney disease (CKD) (i.e. serum creatinine >1.5 mg/dl) secondary to fear of lactic acidosis. The overall incidence of lactic acidosis is estimated at an upper limit of eight cases per 100 000 patient‐years. We evaluated metformin use in two cohorts, one from the University of Chicago Diabetes Center and the other from National Health and Nutrition Examination Survey (NHANES) 1999–2006.

Methods: Estimated glomerular filtration rate (eGFR) was calculated using the re‐expressed Modification of Diet in Renal Disease (MDRD) Study equation and compared to serum creatinine. We hypothesized that metformin is used in patients with undetected advanced CKD (i.e. serum creatinine is ≥1.5 mg/dl). A chi‐squared test was used to compare per cent differences of metformin use across demographic variables and eGFR in the NHANES cohort.

Results: At the University of Chicago Diabetes Center, 36 of 234 (15.3%) patients with an eGFR of <60 ml/min/1.73 m2 were receiving metformin. Data from NHANES, age >18 years and eGFR <60 ml/min/1.73 m2 showed that Blacks with advanced nephropathy were three times more likely to receive metformin.

Conclusions: We conclude that metformin utilization occurs with a higher frequency than predicted by serum creatinine in people with eGFR <60 ml/min/1.73 m2. Given the very low incidence of lactic acidosis, the recommendation should be changed to reflect eGFR cut‐off values rather than serum creatinine.
ACCOUNTING FOR INVESTMENTS IN UNINCORPORATED JOINT VENTURES
Authors: Eddey P. H. , Sullivan G. G.
Published: August 2010

A consideration of the pertinent legal and commercial features of unincorporated joint ventures reveals some accounting and disclosure issues that are not adequately dealt with by existing accounting standards or disclosure rules. In addition, a review of current practice reveals major deficiencies in reporting the financial results of investments in joint ventures. Some deficiencies, especially the disclosure of contingent liabilities, may be in breach of the requirements of the Companies Act, 1961. Our conclusion on accounting methods is that the equity method is to be preferred to the more popular proportionate consolidation method.
ANNUAL REPORT RESOURCE COMMITMENT AND DISTRIBUTION PATTERNS IN AUSTRALASIA
Authors: Courtis John K.
Published: August 2010

In April 1978 a mail questionnaire was administered to 1230 Australian and 215 New Zealand public companies to solicit annual report resource commitment and distribution patterns. Summarized responses indicate that Australian annual reports for year ended 1977 cost A$2.98 per copy on average to produce and mail, while New Zealand reports for the same period cost NZ$2.50. More than half of these costs is attributable to the printing component. Australian companies employed 99 manhours on average in the preparation and distribution of their reports, while New Zealand companies employed 130 manhours. Eighty percent of all reports distributed by Australian companies were sent to shareholders, while 70 percent of all reports distributed by New Zealand companies were sent to this group.
STUDENT ATTITUDES TOWARD ALTERNATIVE INSTRUCTIONAL APPROACHES IN INTRODUCTORY ACCOUNTING
Authors: Mahoney Darrell J. , Clarke Anne
Published: August 2010

This paper reports the results of a survey of student attitudes towards a first year accounting program at the tertiary level. The program incorporates innovatory features including syllabi defined in terms of behavioural objectives, content broken into modules, a range of learning resources for each module and flexible assessment at the student's option. Analysis of responses from two groups of students is presented, those studying in the program and those who had completed the program the previous year. Strong support for the program is apparent from the response analysis. Conclusions indicate that students generally view the program as providing a sound foundation for later accounting studies. In addition, many students consider the program's features would be beneficial in other subject areas.
THE MEASUREMENT OF A FIRM'S COST OF CAPITAL
Authors: Officer R. R.
Published: August 2010

The relevance of a firm's cost of capital in its investment decisions is widely recognised. The concept and associated issues have been and are likely to be increasingly important in the regulatory activities of government and semi‐government bodies, e.g. prices regulation, profit regulation for semi‐government enterprises, antitrust and takeover regulation. This paper outlines the principles involved in estimating a firm's before‐tax and after‐tax cost of capital. The paper also suggests practical approaches that may be taken when difficulties arise in estimating parameters to the problem.
TRANSFER PRICING IN A DEPOSIROTY FINANCIAL INTERMEDIARY: PROOF OF A CONJECTURE FOR THE CASE OF NORMALLY‐DISTRIBUTED CASH WITHDRAWALS*
Authors: Schnabel J. A.
Published: August 2010

In an earlier paper, a source of gains from the centralization of a financial intermediary's management of its cash reserves was conjectured. This note presents a mathematical proof of the conjecture for the special case of normally‐distributed cash withdrawals.
THE INFORMATION CONTENT OF UK ANNUAL EARNINGS ANNOUNCEMENTS: A NOTE
Authors: Maingot Michael
Published: August 2010

The study examined whether UK annual earnings possessed information or not, using Beaver's (1968) residual variance approach methodology. The research confirms results reported in other studies.
THE EFFECTS OF ALTERNATIVE REIMBURSEMENT SYSTEMS ON THE OPERATING BEHAVIOUR OF NURSING HOMES
Authors: Abernethy Margaret A.
Published: August 2010

Nursing home care in Australia is provided by both for‐profit and not‐for‐profit nursing homes. Operating expenditure in nursing homes is funded by the Commonwealth Government. The reimbursement system currently in operation is linked to ownership structure. This paper examines differences in operating behaviour as a result of a reimbursement system based on ownership structure. The results of this study indicate that differences in behaviour occur as a result of ownership differences, ineffective controls and the lack of incentives in the reimbursement system to operate efficiently. These differences have important implications for policy change affecting the funding of nursing home care.
Accounting Information and Joint Arrangements
Authors: Whittred Greg , Zimmer Ian
Published: August 2010

The accounting profession has recently issued a standard (AAS19) on production sharing agreements and has signalled impending regulation of accounting for other types of joint arrangements. Here we discuss the nature of joint arrangements and the role that accounting information plays in causing such arrangements to exist, determining their legal form, safeguarding the interests of the contracting parties, and protecting other interested parties likely to be disaffected by the arrangement.
The Non‐Stationarity of Share Price Volatility
Authors: Hathaway Neville
Published: August 2010

This article examines first the changes over time in the variance of the market return on the Sydney Stock Exchange. It concludes that variance changes at a frequency greater than previously accounted for. Some of these changes coincide with political and economic events. Next the market returns are demonstrated to have a normal distribution. This result follows once the frequency of standardization is matched to the frequency of changes in variance.
The Duration of a Mixed Stream Comprising Positive and Negative Flows
Authors: Ma Ronald , van Ziji Tony
Published: August 2010

This paper shows how the duration measure of a mixed stream comprising positive and negative flows can be derived, and its property as an index of interest elasticity is illustrated. It is shown that Durand's [1974] measure of the duration of a mixed stream is incorrect. Blocher and Stickney [1979], following Durand, used duration measures, some of which relate to mixed streams, in assessing illiquidity risk in capital budgeting. This aspect of their analysis is suspect.
The Development of Meaning in Accounting: An Intertemporal Study
Authors: Houghton Keith A.
Published: August 2010

The measurement of meaning is an important aspect of research in both psychology and education. Using a semantic differential based instrument, the present study examines the development of connotative meanings for certain accounting concepts. Specifically, it measures the change in (1) the meaning of those concepts, and (2) the cognitive structure within which those meanings are held, observed between two points in time (the commencement and conclusion of a MBA accounting course).