bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicted impact on Victoria's ambulance services of a new major trauma system
Authors: Peeters Anna , Smith Karen , Cameron Peter , McNeil John 
Published: March 2003

Background:   In 1999, a new major trauma system was proposed for the state of Victoria, Australia. The guidelines for the new system were aimed at delivering major trauma cases to definitive trauma care in the least time possible. The aim of the present study was to analyse the potential effect of this system on Victoria’s ambulance services.Methods:  The present study modelled the workload of major trauma cases in Victoria’s ambulance service for one year pre‐ and post‐introduction of the guidelines. Cases were analysed regarding whether their first hospital destination would change under the proposed guidelines, and, subsequently, whether they would require interhospital transport to a higher level trauma service. The impact on the ambulance services was modelled as annual changes in distances travelled due to predicted changes in hospital destinations.Results:  Analysis of the predicted changes indicated that, in general, Victoria"s metropolitan and rural road ambulance crews would not be greatly affected. However, some metropolitan road crews may have to travel extra distances for up to 110 cases per year. The major impact was on air retrieval crews, where the annual number of interhospital transfers is predicted to increase from approximately 150 to 330.Conclusions:  The present study demonstrated that most of the impact of a new trauma system on Victoria"s ambulance services could be readily absorbed into the current workload. However, it also highlighted areas affected disproportionately within the ambulance services; in particular, air retrieval. Such studies are important to enable the effective implementation of new trauma systems.
Incidence of heterotopic bone formation after major hip surgery
Authors: Neal Bruce , Gray Harley , MacMahon Stephen , Dunn Louisa 
Published: March 2003

Background:  Heterotopic bone formation is a well‐established complication of major hip surgery, but traditional reviews of the published literature may have underestimated its frequency.Methods:  A systematic overview of all the relevant studies was performed to determine reliably the incidence of any heterotopic bone formation and the incidence of each Brooker equivalent grade. Separate estimates were made for patients with total hip replacement and patients with acetabular fracture repair.Results:  A computer‐based search identified 218 studies with data on the incidence of heterotopic bone formation after either hip replacement or acetabular fracture repair. These studies included data from an estimated 59 121 operated hips among patients that received total hip replacement and an estimated 998 hips among patients that underwent acetabular fracture repair. In these studies, the incidence of any heterotopic bone formation was 43% after total hip replacement and 51% after acetabular fracture repair. The incidence of severe heterotopic bone formation was 9% and 19%, respectively.Conclusions:  These results suggest that heterotopic bone formation occurs more frequently after total hip replacement than is generally believed. It is possible that heterotopic bone formation is a more important cause of postoperative disability than has previously been recognized and that effective prophylactic regimens might improve outcome in substantial numbers of patients.
Temporal trends and clinical correlates for the ret/PTC1 mutation in papillary thyroid carcinoma
Authors: Burgess John R. , Skabo Stuart , McArdle Kathryn , Tucker Paul 
Published: March 2003

Background:  The incidence of papillary thyroid carcinoma (PTC) has increased in Australia at a rate exceeding 10% per annum over the past two decades. In Tasmania the increase has averaged 24% per year between 1982 and 1997. Exposure to ionizing radiation is the best characterized risk factor for PTC. Oncogenic mutations of the RET proto‐oncogene (ret/PTC rearrangements) have been associated with PTC arising following radiation exposure. In the present study it was sought to determine if PTC incidence trends were associated with an increased occurrence of the ret/PTC1 rearrangement.Methods:  All cases of PTC diagnosed in Tasmania during the even numbered years 1978−1998 inclusive were sought for study (n = 98). Archival histopathology blocks for 62 cases were located. The RNA was successfully extracted from 41 tumours and ret/PTC1 status assessed by reverse transcription−polymerase chain reaction.Results:  The ret/PTC1 mutation was found in 26 (63%) of PTC. The mean age at diagnosis for ret/PTC1‐positive and ret/PTC1‐negative tumours was 46.5 ± 15.46 and 41.9 ± 13.45 years, respectively. The ret/PTC1 positivity was significantly associated with larger tumour size. However, ret/PTC1 was not associated with an adverse prognosis. The prevalence of tumours positive for ret/PTC1 remained stable over the study period (1978−1998) and did not exhibit birth year or diagnosis year clustering.Conclusion:  This is the first study to map temporal trends for the prevalence of ret/PTC1 relative to incidence trends for PTC. Although the ret/PTC1 mutation was frequently identified in Tasmanian PTC, there was no clear relationship between ret/PTC1 and recent PTC incidence trends.
Immunological findings in acute and chronic pancreatitis
Authors: Bhatnagar Archana , Wig Jai Dev , Majumdar Siddartha 
Published: March 2003

Background:   In order to identify the role of mononuclear cells in pancreatitis, the immune picture at the cellular level has been studied. The cytokine production at the individual cell level in response to in vitro stimulation can help in identifying the percentage of specific cell types producing a particular cytokine.Methods:  A total of 30 patients with acute pancreatitis (AP; n = 15) and chronic pancreatitis (CP; n = 15) were entered into the study and peripheral blood samples were drawn at the time of admission. A control group of 12 healthy individuals (age and sex matched) were also included in the study. Mononuclear cells from the peripheral blood from all three groups were separated on Ficoll gradient and labelled for surface antigens (i.e. cluster of differentiation (CD)3, CD4, CD8, CD25, CD14 and human leucocyte antigen D receptor (HLA‐DR)) using monoclonal antibodies. The CD3+ and CD14+ cells were also stained for intracellular cytokines by specific monoclonal antibodies (i.e. for interferon (IFN)‐γ, interleukin (IL)‐2, IL‐4 & IL‐10 in CD3+ cells and IL‐6 and IL‐12 in CD14+ cells). These fluorochrome‐labelled cells were analysed on the flow cytometer.Results:  The T‐cell population is affected in pancreatitis where the CD4+ and CD8+ T‐cell numbers are significantly altered. There is a marked reduction in CD4+ T cells in AP and CP. The CD8+ T cells were significantly reduced in AP. The IL‐2 receptor is expressed in large numbers in AP and CP patient groups. The T cells from the CP group had a typical IL‐2, IL‐4 secreting pattern, while AP patients had a high IL‐10, IFN‐γ and low IL‐2, IL‐4 population. The HLA‐DR expression on monocytes differed significantly between the two groups, being strikingly reduced in chronic cases and significantly reduced in acute cases. The percentage of IL‐6‐producing monocytes was significantly higher in patients with AP as well as CP while IL‐12 levels were higher in the CP than in the AP group.Conclusions:  T cells in CP are polarized towards the T‐helper (Th)1 phenotype while the AP patients had a mixed population. This seems to be a part of immune deviation that is associated with development of CP and IL‐12 appears to be instrumental in this process. The monocytes synthesize proinflammatory cytokines, which play an important role in the local and systemic consequences of the disease. In the disease clinical assessment such a study can provide useful information about the involvement of the immuno­inflammatory system.
PRACTICE GREEN ENGINEERING, KEEP THE JUNKYARDS CLEAR
Authors: Rosenfield  
Published: March 2003

This paper discusses the fracture prevention aspects of lifetime prediction. Initially, it is pointed out that lifetime can be determined by factors such as obsolescence and consumer rejection. Lifetime is then related to acceptable risk in order to make it compatible with advances in design philosophy for large welded structures.Accident statistics are cited and the argument made that the major opportunities for lifetime improvement are revealed by failure analysis, and are shown to lie in design and production. However, there are some structures, e.g. boilers and pressure vessels, where the construction rules are so well established that failures occur mainly because of operational errors.Based on the results of the Battelle/NBS Cost of Fracture Study, attention is focused on the effect of material–property reproducibility in driving failure probability. Little evidence could be found regarding reproducibility improvements of fatigue lifetime and brittle fracture toughness in production lots of alloys over time.
FATIGUE CRACK GROWTH DUE TO TWO SUCCESSIVE SINGLE OVERLOADS
Authors: Hammouda  , Ahmad  , Seleem  , Sallam  
Published: March 2003

The behaviour of fatigue growth and cyclic tip deformation of long cracks due to two successive single overloads was investigated both experimentally and numerically. The results show the effect of the ratio of the second and first overloads, and the crack increment between the two overloads. The contributions of both crack tip blunting and residual stress fields were separated and accommodated in a previously developed crack tip deformation parameter, which was utilized to predict the resulting fatigue crack growth behaviour.The following trends were experimentally observed. Should the ratio of the second and first overloads not be less than one, fatigue crack growth rates followed the predictions based on the second overload. Otherwise, either of the following two situations resulted: (1) when the two overloads were closely applied, the second overload caused an initial acceleration in growth rates followed by a behaviour controlled by the first overload; (2) when the second overload was applied after the crack growth had reached its minimum rate due to the first overload, more retardation in growth rate was observed.Based on the model developed in the paper, it is possible to enhance the retardation effect of an overload if this overload is preceded by another overload. This enhancement depends on the ratio of the two overloads and the crack increment between them.
A phenomenological model of fatigue macrocrack initiation near stress concentrators
Authors: Ostash  , Panasyuk  , Kostyk  
Published: March 2003

ABSTRACTFatigue macrocrack initiation is considered to be a two‐parameter process. It is governed by the local or strain amplitude, and a certain linear parameter of the material. Corresponding parameters have been proposed, i.e. the local stress range Δσ*y and a characteristic distance d *, the prefracture zone size. The formation of this zone is conditioned by a decrease in yield strength within the material’s surface layers, microstructure, loading amplitude, cyclic strain hardening and environment. The value of d * is estimated experimentally by several methods and is assumed to be a certain material constant, independent of both notch and specimen geometry. At the prefracture zone boundary, a major barrier exists that retards the growth of a physically small fatigue crack. The moment when the physically small crack overcomes the prefracture zone boundary is assumed to be a quantitative criterion, ai = d *, for the micro‐ to macrocrack transition. The proposed relationships, Δσ*y versus Ni , and d * versus Ni , can be used as a basis for the establishment of the materials resistance to macrocrack initiation.
A two‐dimensional elastic–plastic finite element analysis of friction effects on sliding crack surfaces in full or partial contact
Authors: Hammouda  , El‐Sehily  
Published: March 2003

AbstractSliding crack surfaces are analysed, that are completely or partially in contact, using a two‐dimensional plane‐stress elastic–plastic finite element technique. Our in‐house program was modified to account for the friction which acts between two rough mating surfaces. The analysis is applied to a cantilever beam cracked along its span through its centroidal plane. Twelve cracks with length‐to‐span ratios ranging from zero to 0.5 were analysed. The effect of friction was investigated by considering 0, 0.4, 0.8, 1.2 and 1.6 as values for the coefficient of friction with each crack length. The results show the influence of friction on the beam stiffness, strain energy release rate, modes of crack tip and surface displacements, and the development of plastic deformation. The present finite element outputs assist in the explanation of experimental events associated with mode II crack tip displacement data found in the literature.
Interfacial fatigue crack growth in foam core sandwich structures
Authors: Shipsha  , Burman  , Zenkert  
Published: March 2003

ABSTRACTThis paper deals with the experimental measurement of face/core interfacial fatigue crack growth rates in foam core sandwich beams. The so‐called ‘cracked sandwich beam’ specimen is used, slightly modified, which is a sandwich beam that has a simulated face/core interface crack. The specimen is precracked so that a more realistic crack front is created prior to fatigue growth measurements. The crack is then propagated along the interface, in the core material, during fatigue loading, as is assumed to occur in a real sandwich structure. The crack growth is stable even under constant amplitude testing. Stress intensity factors are obtained from the FEM which, combined with the experimental data, result in standard da/dN versus ΔK curves for which classical Paris’ law constants can be extracted. The experiments to determine stress intensity factor threshold values are performed using a manual load‐shedding technique.
Damage mechanics models of ductile crack growth in welded specimens
Authors: Burstow M. C. , Howard I. C. 
Published: March 2003

Two‐dimensional, plane strain, finite element analyses of strength‐mismatched welded joints have been performed using the modified boundary layer formulation. The welds were idealized as two‐material joints with the material interface running parallel to the crack, which was embedded in the weld material. The Rousselier ductile damage model was employed within the weld material to simulate crack extension due to the growth and coalescence of microvoids. By analysing models with different levels of material mismatching, weld dimensions and applied T‐stress levels, it was possible to analyse the effects of crack tip constraint due to both material mismatching and specimen geometry on the fracture resistance of the weld material.The results show that material strength overmatching (where the weld material is stronger than the base material) reduces the level of constraint ahead of the crack, which can increase the resistance to fracture of the weld material. Conversely, material strength undermatching increases crack tip constraint, reducing the fracture resistance of the joint. By employing estimates for the crack tip constraint levels, QM , based on the applied load, level of material mismatching and weld region thickness, it has been possible to ‘order’ the J–resistance curves of overmatched joints by generating a family of J–QM loci which describe the effects of constraint on the fracture resistance of the weld material. However, it is shown that the QM‐stress parameter is not capable of describing the effect of material strength undermatching on the fracture resistance of a joint, which can be much lower than that obtained from a high‐constraint homogeneous specimen of weld material.
Mode I stress intensity factors for curved cracks in gears by a weight functions method
Authors: Guagliano M. , Vergani L. 
Published: March 2003

The most recent trend in power transmission design considers the damage‐tolerant approach as one of the methods to obtain safe, reliable and light systems. This means that components containing cracks must be considered and analysed to understand the conditions that cause critical cracks and defects and their dimensions.In this paper a cracked tooth of an automotive gearwheel is considered. A numerical procedure (based on the slice synthesis weight function method) to calculate the stress intensity factors of curved cracks due to bending loads is illustrated. The results are compared with those obtained by expensive finite element calculations. The agreement is satisfactory and the proposed technique proves to be very attractive from the point of view of time saving.One example of an application to fatigue design practice is provided, namely the analysis of fatigue crack propagation in surface‐treated gears. The results show the role played by residual stresses induced by carburizing and shot peening.
Local texture and fatigue crack initiation in a Ti‐6Al‐4V titanium alloy
Authors: Le Biavant K. , Pommier S. , Prioul C. 
Published: March 2003

ABSTRACT Fatigue crack initiation was studied in a bimodal TA6V titanium alloy. A ghost structure inherited from the forging process, the scale of which is roughly 100 times the apparent grain size, was found to govern the initiation process. In these macrograins, that we have labelled macrozones, most of the primary alpha grains (αp) are found to display the same crystallographic orientation. Fatigue cracks are initiated on the basal plane or, if basal slip is difficult, on the prismatic plane. Thus in macrozones, where basal or prismatic slip is easy, numerous neighbouring tiny cracks appear over the whole macrozone, which have the size of the primary αp grains. In these macrozones the contribution of crack coalescence to crack growth is consequently very significant. On the contrary, if basal and prismatic slips are both difficult in the macrozone, no crack can be found in the corresponding macrozone. The crack initiation process is thus highly heterogeneous at the scale of the macrozone. Furthermore, this microstructure is found to induce a large scatter in the fatigue life of notched samples.
‘Arching’ effect in elastic polycrystals: implications for the variability of fatigue lives
Authors: Pommier S. 
Published: March 2003

ABSTRACT The paper deals with a study of heterogeneous stress and strain distribution in polycrystals in relation with elastic anisotropy of grains. A similitude with the arching effect widely studied in granular materials is proposed and this concept is extended to heterogeneous polycrystals in which the load transfer is not binary in the way it is in granular media but may vary significantly and suddenly from one grain to another according to the crystal orientation to the load direction. Experiments and 3D finite element analyses show that though the individual orientation of grains is random, the strain and stress distribution is not. A network is formed inside the polycrystal whose scale is larger than the grain size. The load percolation network consists in heavily loaded links whose direction is coincident with the direction of the principal stresses. So, the typical scale for the variability of the local stresses is not the grain size but the size of the load percolation network. Since this scale is found to be rather large in particular for iron, zinc and copper, this effect should contribute significantly to the variability of the fatigue lives of notched vs. smooth components.
The effect of material behaviour on the analysis of single crystal turbine blades: Part II – Component analysis
Authors: Maclachlan D. W. , Knowles D. M. 
Published: March 2003

ABSTRACTThis paper describes the analysis of a turbine blade component using a slip system model developed for modern single‐crystal superalloys. Structural elasto‐viscoplastic calculations are carried out for the component. The emphasis throughout is on the effect of micromechanisms of deformation, accounted for in the material model, on the predicted overall behaviour of the component. With the recent proliferation in detailed material models that are available, it is prudent to take a step back and investigate the implications of such models for component analysis and design. This effect is manifested through the determination of a stabilised and redistributed stress state throughout the component. While some components are creep‐limited in design, many are fatigue‐limited and it is stabilised stresses which control the cyclic life of these components. The accuracy of the material model, incorporating various micromechanisms as a function of stress and temperature, can significantly effect these stabilised stresses. The effect of the crystallographic orientation on blade behaviour is illustrated and the implications of shakedown simulations for fatigue lifing of turbine blades are discussed.
Crack growth behavior and fatigue‐life prediction based on worst‐case near‐threshold data of a large crack for 9310 steel
Authors: LIU J. Z. , WU X. R. , DING C. F. , HU B. R. , WANG L. F. , ANNIGERI B. , VESTERGAARD L. H. , ROMANOWSKI A. , SCHNEIDER G. J. , FORTH S. C. 
Published: March 2003

ABSTRACT Both experimental and analytical investigations were conducted to study crack initiation and growth of small cracks, near‐threshold growth behavior of large cracks at constant R‐ratio/decreasing ΔK and constant Kmax/decreasing ΔK, respectively, for 9310 steel. The results showed that a pronounced small‐crack effect was not observed even at R = −1, small cracks initiated by a slip mechanism at strong slip sites. Worst‐case near‐threshold testing results for large cracks under several Kmax values showed that an effect of Kmax on the near‐threshold behavior does not exist in the present investigation. A worst‐case near‐threshold test for a large crack, i.e. constant Kmax/decreasing ΔK test, can give a conservative prediction of growth behavior of naturally initiated small cracks. Using the worst‐case near‐threshold data for a large crack and crack‐tip constraint factor equations defined in the paper, Newman's total fatigue‐life prediction method was improved. The fatigue lives predicted by the improved method were in reasonable agreement with the experiments. A three‐dimensional (3D) weight function method was used to calculate stress‐intensity factors for a surface crack at a notch of the present SENT specimen (with r/w = 1/8) by using a finite‐element reference solution. The results were verified by limited finite‐element solutions, and agreed well with those calculated by Newman's stress‐intensity factor equations when the stress concentration factor of the present specimen was used in the equations.
High‐cycle rotating bending fatigue property in very long‐life regime of high‐strength steels
Authors: OCHI Y. , MATSUMURA T. , MASAKI K. , YOSHIDA S. 
Published: March 2003

ABSTRACT In order to investigate the fatigue properties of high‐strength steels in the very long‐life regime up to over 109 cycles, cantilever‐type rotating bending fatigue tests were carried out for two kinds of high‐strength steels, SUJ2 and SNCM439, which were machined by grinding and finished by electropolishing after grinding. And also, the residual stress on the specimen surface of the ground specimen was examined by X‐ray diffractometer in order to investigate effects of the residual stress on the fatigue properties. From the investigations, the S–N curves clearly have a tendency to decrease again in the longer‐life range over 107 cycles for both types of specimen and for both steels. From observations of fracture surfaces, it was found that fatigue crack origins could be grouped into two types: (i) ‘surface crack origin type’ in the shorter‐life regime and (ii) ‘internal crack origin type’ in the longer‐life regime.