bluuebunny/crossref_metadata_2025 huggingface dataset:
CONCURRENT GASTRIC AND COLONIC LOW‐GRADE MUCOSA‐ASSOCIATED LYMPHOID TISSUE LYMPHOMATA IN A PATIENT WITHOUT HELICOBACTER PYLORI INFECTION
Authors: OKADA HIROYUKI , MIZUNO MOTOWO , YOSHINO TADASHI , YOKOTA KENJI , OKAZAKI HIROAKI , OKANO NOBUAKI , NASU JUNICHIROU , MANNAMI TOMOHIKO , OGUMA KEIJI , AKAGI TADAATSU , TSUJI TAKAO , SHIRATORI YASUSHI
Published: March 2003

Mucosa‐associated lymphoid tissue (MALT) lymphomata observed simultaneously in the stomach and colon are rare. We report concurrent gastric and colonic low‐grade MALT lymphomata that originated from the same clone in a 58‐year‐old Japanese man without Helicobacter pylori infection. Endoscopy showed multiple erosive lesions in the gastric body and antrum, and a single flat elevation with an irregular margin in the sigmoid colon. Histopathological findings of both lesions suggested low‐grade MALT lymphoma. Lymphoepithelial lesions were evident in the gastric lesions, but not in the colonic lesion. Southern blot analysis of lymphoma cells revealed the same immunoglobulin heavy‐chain rearrangement pattern. The chromosomal translocation t(11;18)(q21;q21) was also observed. After six courses of cyclophosphamide, doxorubicin, vincristine and predonisolone, the gastric lesions disappeared endoscopically, while the colonic lesion persisted. A sigmoidectomy was consequently performed. The chromosomal translocation may be related to the pathogenesis of the present MALT lymphoma case without H. pylori infection. It is interesting that the gastric and colonic lesions differed in response to treatment and in their endoscopic and histologic features, despite having the same origin.
CLINICOPATHOLOGICAL STUDY OF UNSUSPECTED GALLBLADDER CANCER DIAGNOSED AFTER LAPAROSCOPIC CHOLECYSTECTOMY
Authors: SAKAMOTO KAZUHIRO , KITAJIMA MASAYUKI , SHIROTA SHIGERU , WATABE SUGURU , OKUZAWA ATSUSHI , MATSUDA MITSUHIRO , ONO KEN , KOBAYASHI SHIGERU , KAMANO TOSHIKI , TSURUMARU MASAHIKO , HIRAI SHU
Published: March 2003

Background:  Laparoscopic cholecystectomy (LC) has become a common treatment for benign gallbladder diseases. However, this method has not been established for gallbladder cancer.

Methods:  In the present study, we examined the clinicopathlogical features of gallbladder cancer that was diagnosed after LC.

Results:  The presence of unsuspected gallbladder cancer was found in five out of 498 patients (1.00%). Preoperative diagnoses were gallstone in two, gallstone with adenomyomatosis in one, adenomyomatosis in one and gallbladder polyp in one. During LC, there was no evidence of cancer, but bile leakage occurred in two patients. Histologically, the carcinoma had invaded into the subserosa in four patients and into the mucosa in one patient. An additional operation was performed in three patients. Histological examination revealed no cancer cells in the resected liver and lymph nodes. During the average follow‐up period of 47.5 months, no recurrences were observed. Although one patient died of liver metastasis 33 months later, the other three patients who underwent an additional radical operation, showed no recurrence.

Conclusions:  It is important to prevent port site recurrence or dissemination during LC, so a careful maneuver is required to avoid perforation of the gallbladder. At the time of bile leakage, it is best to wash around the liver bed fully to prevent recurrences of unsuspected gallbladder cancers. If gallbladder cancer has invaded the subserosa or deeper level histologically, a radical second operation should be performed as soon as possible.
Miniprobe sonography in the evaluation of 169 patients with gastrointestinal disease
Authors: Qi Zhu , Yaozong Yuan , Jiayu Xu , Fengzhao Wang , Shihu Jiang , Yunlin Wu , Peiqing Zhao
Published: March 2003

OBJECTIVE: It is still difficult to precisely differentiate elevated lesions of the gastrointestinal mucosa or estimate the depth of malignant lesions by using conventional endoscopy and biopsy. The aim of the present study was to assess the clinical value of miniprobe sonography (MPS).

METHODS: A total of 169 patients (including 83 patients who underwent endoscopic treatment or surgery) with gastrointestinal disease were examined by using MPS in conjunction with endoscopic examination. The diagnosis according to MPS was compared with macroscopic findings, endoscopic biopsy and surgical results.

RESULTS: In the case of elevated lesions of the gastrointestinal mucosa with negative biopsies, compared with surgical findings, the diagnostic accuracy of MPS was 98.3% (115/117). In the case of malignant lesions, MPS findings with regard to the lesion depth were 100% in agreement with those from surgical biopsy (31/31).

CONCLUSION: The MPS technique is significantly superior to conventional endoscopy with pathological biopsy in the differentiation of elevated lesions of the gastrointestinal mucosa and thus has important clinical value. But in the case of malignant lesions, only the depth of infiltration into the gastrointestinal wall can be correctly assessed by MPS, so its value is limited in the identification of lymph nodes and distal metastases.
Parkinsonism in patients with subcortical arteriosclerotic encephalopathy: A magnetic resonance imaging study
Authors: Hanyu Haruo , Tanaka Yuriko , Asano Tetsuichi , Sakurai Hirofumi , Iwamoto Toshihiko , Takasaki Masaru
Published: March 2003

Background: The aim of the present paper was to determine anatomical brain damage causing parkinsonism in patients with subcortical arteriosclerotic encephalopathy.

Methods: Using magnetic resonance imaging, the findings in 16 subcortical arterio‐sclerotic encephalopathy patients with parkinsonism were compared with those of 16 subcortical arteriosclerotic encephalopathy patients without parkinsonism. In addition to conventional magnetic resonance imaging, the magnetization transfer technique was also employed, and the magnetization transfer ratios of white matter hyperintensity lesions in the frontal lobe were measured to detect structural changes.

Results: The extent of infarcted lesions in the lentiform nucleus of patients with parkinsonism was significantly greater than in patients without parkinsonism. Although white matter hyperintensity areas did not differ significantly between the two patient groups, magnetization transfer ratios in the white matter hyperintensity lesions of patients with parkinsonism were significantly lower than those of patients without parkinsonism. The lower magnetization transfer ratios suggest that tissue damage of white matter lesions in patients with parkinsonism is more severe than in patients without it.

Conclusion: Both severe tissue damage in the frontal white matter and extensive infarcted lesions in the lentiform nucleus might be responsible for the development of parkinsonism in patients with subcortical arteriosclerotic encephalopathy.
Prevalence and characteristics of older community residents with mild cognitive decline
Authors: Fujiwara Yoshinori , Watanabe Shuichiro , Kumagai Shu , Yoshida Yuko , Takabayashi Koji , Morita Masahiro , Hasegawa Akihiro , Hoshi Tanji , Yokode Masayuki , Kita Toru , Shinkai Shoji
Published: March 2003

Background: Cognitive impairment is a major health issue, but epidemiological data on mild cognitive decline have been almost absent in Japan.

Methods: Of all residents aged 65 years and over living in Yoita town, Niigata Prefecture, Japan in the year 2000 (n = 1673), 1544 participated in the interview survey held at community halls or at home (92.3% response). They underwent the Mini‐Mental State Examination (MMSE) for assessment of cognitive function and answered questionnaires comprising socio‐demographic, psychological, physical and medical, and social activity items. Higher‐level functional capacities were evaluated with the Tokyo Metropolitan Index of Competence (TMIG‐Index of Competence). According to subject’s age and MMSE score, all subjects were classified into 3 groups: control (MMSE > 1 SD below age‐specific means), mild cognitive decline (MMSE ≥ 21 and ≤ 1 SD below age‐specific means), and severe cognitive decline (MMSE ≤ 20), and compared various characteristics among these groups.

Results: Mean MMSE score of the subjects showed a linear decline with advancing age. Among the participants, 232 (15.2%) were classified as mild cognitive decline. Compared with the controls, the subjects with mild cognitive decline reported poorer subjective health, more depressive moods, more history of stroke, more prevalence of basic activity of daily living (BADL) disability, and lower higher‐level functional capacity, even after controlling for possible confounding factors. They also reported a low level of social activities: both participating in group activities and enjoying hobbies were less frequent. Their food intake pattern tended to be monotonous.

Conclusions: Older persons with mild cognitive decline comprised a substantial proportion (15.2%) of the community‐dwelling older population. In addition to lower cognitive function, they had lower levels of functional capacity and social activity.
Association between a promoter polymorphism of the paraoxonase PON1 gene and pathologically verified idiopathic Parkinson’s disease
Authors: Kazama Hirohito , Hosoi Takayuki , Nakahara Ken‐ichi , Murayama Shigeo , Saito Yuko , Kanemaru Kazutomi , Nagura Hiroshi , Arai Tomio , Sawabe Motoji , Toba Kenji , Yamanouchi Hiroshi , Orimo Hajime
Published: March 2003

Background:  Exposure to pesticide is associated with an elevated risk of Parkinson’s disease (PD). Oxidative stress is also implicated in the etiology of PD. Paraoxonase (PON1) detoxifies organophosphates and exhibits antioxidant properties. It was postulated that polymorphisms of the PON1 gene lead to increased risk of PD.

Methods:  The seven polymorphisms of the PON1 gene were typed and neuropathologic examination performed in 360 Japanese people (191 men and 169 women) consecutively autopsied at a general hospital.

Results:  Thirty‐three patients (18 men and 15 women) were diagnosed with pathologically verified idiopathic PD (pviPD). The proportion of male patients with pviPD was highest in the AA genotype (29.4%) of the G(−824)A polymorphism, followed by the GA genotype (9.3%), and least in the GG genotype (6.0%). These genotypic distributions and allele frequency were significantly different between male patients with and without pviPD (P = 0.021 and P = 0.012, respectively). The odds ratio for the −824 A allele versus the −824G allele was 2.47 (95% CI 1.23–4.96). No association between pviPD and the PON1 polymorphisms was found in the female patients.

Conclusion:  Possession of the −824A allele may increase the risk of PD in Japanese men.
Management of the acute scrotum in children
Authors: Corbett Harriet J. , Simpson Erroll T.
Published: March 2003

Background: The study investigates the hypothesis that testicular torsion is over‐diagnosed by emergency department (ED) doctors. Diagnoses made by ED doctors are compared with those made by a surgical registrar or specialist and the review outcome by a surgical registrar or specialist on diagnosis and management is evaluated.

Methods: Medical records of all boys up to the age of 14 years who presented with an acute scrotum to the ED at The Canberra Hospital between October 1995 and October 2000 were retrospectively reviewed.

Results: A total of 182 boys presented to the ED on 190 occasions; mean age of presentation was 10.1 years and mean time from onset of pain to presentation was 27.6 h. Ninety (47.4%) patients had a torted testicular appendage, 23 (12.1%) had testicular torsion and 12 (6.3%) had epididymitis or orchitis. Eighty‐one patients underwent surgery, in whom 61 were excluded from having testicular torsion. Testicular torsion was suspected by ED doctors in 57.5% of patients, by registrars in 35.4% and by specialists in 17.7%. Overall, the correct diagnosis was made by ED doctors in 39% of patients, by registrars in 53% and by specialists in 76%.

Conclusions: Less experienced examiners suspect testicular torsion more frequently than surgical registrars or specialists. Review of the patient by an experienced examiner should allow for more accurate initial diagnoses and spare some children unnecessary surgical procedures.
Laparoscopic repair of ventral incisional hernia
Authors: Kua Keith B. , Coleman Mark , Martin Ian , O’Rourke Nicholas
Published: March 2003

Background: Laparoscopic repair of ventral incisional hernias was first reported in 1993. Since then, there have been sporadic case reports and small series published about this procedure, but it has not been widely adopted. Newer types of composite prosthetic mesh may reduce the potential problem of bowel adhesion.

Methods: Thirty cases of laparoscopic ventral incisional hernia repairs (carried out by two surgeons or their senior registrars) have been retrospectively reviewed and reported in this article. The data were obtained from patient records and subsequent phone surveys.

Results: Thirty patients between 29 and 82 years (mean: 58 years) underwent this procedure. There were 14 men and 16 women. The average weight of the patients was 81 kg. The hernias were up to 6 or 7 cm in diameter. Mesh was used in 28 cases (polypropylene in 25 cases, expanded polytetrafluoroethylene in two cases and composite mesh in one case). Most meshes were laid intraperitoneally and fixed into position with laparoscopic spiral tacks. Twenty‐nine cases were completed laparoscopically. One operation (3.3%) was converted to an open procedure because of severe bowel adherence to the hernia sac. The mean operating time was 52 min for laparoscopic ventral incisional hernia repairs only. All but two patients tolerated an oral diet within 24 h. The postoperative hospital stay ranged from 0 to 11 days, with 17 patients (57%) staying overnight and eight patients (27%) staying another day. Over 80% of the patients returned to house duties within a week. There was no mortality, and minor complications occurred in four patients (14%). One patient had a small bowel obstruction treated successfully by repeat laparoscopy with division of fibrinous adhesions to polypropylene mesh on day four. Follow up ranged from 1 to 69 months (mean: 12 months). One patient did not attend follow‐up appointments. There were three cases of hernia recurrence (10%).

Conclusion: The results suggest that laparoscopic repair of ventral incisional hernias is a safe, effective and technically feasible operation for small‐ to medium‐sized hernias allowing shorter hospital stay, early recovery and resumption of normal activities. However, recurrence rates are comparable to open mesh hernioplasty especially for larger hernias.
Extent of mesorectal invasion is a prognostic indicator in T3 rectal carcinoma
Authors: Steel Malcolm C. A. , Woods Rodney , Mackay Jack M. , Chen Frank
Published: March 2003

Background:  The aim of this study was to determine if local recurrence (LR) rates in patients with minimally invasive and advanced T3 rectal cancer are different. This may influence the use of adjuvant therapy.

Methods:  Consecutive patients with T3 rectal cancer undergoing curative surgery were classified into minimally invasive or advanced groups. Minimally invasive T3 was defined as a tumour that had invaded beyond the muscularis propria on microscopic examination only, whereas advanced T3 tumours had invasion beyond the muscularis propria that was obvious on macroscopic examination and confirmed histologically. Local recurrence rates of the two groups were compared by construction of Kaplan−Meier curves. The log‐rank test was used to determine equivalence, and Cox regression to estimate the hazard ratio. The Grambsch− Therneau test and graphical comparison of predicted and observed Kaplan−Meier curves was used to test the proportional hazards assumption.

Results:  There were 222 patients in total, 74 in the minimally invasive group and 148 in the advanced. The overall LR rate was 11.2%. The LR rates in the minimally invasive and advanced groups were 5.4% and 14.2%, respectively. The log‐rank test gives a P value of 0.042 for equivalence, with the minimally invasive patients doing significantly better. The hazard ratio estimated by Cox regression was 0.35 (early relative to advanced), 95% confidence intervals (0.12, 1.0). There was no evidence of confounding by age at surgery, pathology type, gender or postoperative adjuvant therapy.

Conclusions:  The extent of invasion into the mesorectum appears to be an independent prognostic variable. If oncologically sound surgical techniques are employed, the LR rate of patients with minimal invasion is low. Adjuvant therapy may not confer additional benefit in this group.
Baseline comparisons in surgical trials
Authors: Hall John C. , Hall Jane L.
Published: March 2003

Introduction:  Baseline measurements are an essential component of clinical trials. They should establish that the groups involved are clinically equivalent so that any observed differences can be attributed to the intervention under evaluation. The objective of this study was to review the use of baseline comparisons in surgical trials.

Methods:  A standardized format was used to evaluate 206 surgical trials published within 10 prestigious journals between January 1997 and December 1999.

Results:  One hundred and fifty‐one (73%) of the trials used the first table in the article to record baseline data. More than one‐quarter of the trials declared less than five items and one‐third of the trials inappropriately used ‘P‐values’ as a measure of baseline equivalence. Only nine of the 54 multicentre studies (17%) mentioned the individual centres as possible confounding factors.

Discussion:  Greater attention needs to be paid to baseline comparisons in surgical trials. One way of developing this type of critical ability is to use a checklist while reading a surgical trial of interest. Good resources include the CONSORT Statement by a group of prominent international biostaticians and the CLEAR (Critical Literature Evaluation and Research) Courses run by the Royal Australasian College of Surgeons.
Ankle fractures: Functional and lifestyle outcomes at 2 years
Authors: Lash Nicholas , Horne Geoffrey , Fielden Jann , Devane Peter
Published: March 2003

Background:  Ankle fractures form a high proportion of the total number of fractures treated in New Zealand. International studies show that there are mixed functional outcomes with differing fracture types and subsequently differing lifestyle outcomes.

Methods:  Fracture clinic records and orthopaedic admissions books for Wellington Public Hospital, Capital Coast Health, ­Wellington, were retrospectively reviewed to gain a population of patients who sustained ankle fractures for the period January−­December 1998. These patients were asked to fill in postal questionnaires detailing their current ankle function and lifestyle, two years after fracturing their ankle. The patients’ radiographs were reviewed to classify the types of ankle fractures sustained.

Results:  Of 141 patients that sustained ankle fractures, 74 were followed up 2 years after their ankle fracture. All fracture types averaged Olerud‐Molander ankle scores of 71.1. Weber A fractures averaged ankle function scores of 90, Weber B fractures 80, and Weber C fractures 78. Four patients (5%) achieved ‘poor’ results, 12 (16%) patients achieved a ‘fair’ result, 30 (41%) patients gained a ‘good’ result, 27 (36%) patients attained ‘excellent’ results. Lifestyle outcomes were reflected in the patient’s ankle function outcomes (P < 0.05).

Conclusion:  Patients who sustain ankle fractures can be expected to be still experiencing functional difficulties two years post‐treatment.
Parathyroid autotransplantation during thyroidectomy
Authors: Lo Chung‐Yau
Published: March 2003

Permanent hypoparathyroidism is a debilitating morbidity following thyroidectomy, with a reported incidence of up to 43%. Apart from meticulous dissection to preserve parathyroid glands and their blood supply, parathyroid autotransplantation (PA) has been increasingly employed to preserve parathyroid function. The adoption of PA during thyroidectomy has been reported to be associated with a low incidence of permanent hypoparathyroidism. Biochemical function of parathyroid autografts can be demonstrated objectively by forearm reimplantation or during long‐term follow up. The clearest indication for PA is for inadvertently removed or devascularized parathyroid glands during thyroid surgery. Other strategies, including routine autotransplantation of at least one parathyroid gland, can be considered, but is associated with a high incidence of transient hypocalcaemia. Apart from refinement in technique to facilitate graft success, a reliable way to assess overall parathyroid function or viability of individual parathyroid gland may assist in monitoring parathyroid function and selecting patients requiring this procedure to prevent permanent hypoparathyroidism.
Paediatric elective surgical conditions as seen at a referral hospital in Kumasi, Ghana
Authors: Abantanga Francis A. , Amaning Eric P.
Published: March 2003

Background:  Data on paediatric surgical conditions in sub‐Saharan countries, including Ghana, are scanty and sketchy. Using hospital‐based data, it is possible to assess the epidemiology of diseases among children, and the morbidity and mortality rates.

Methods:  Between January 1997 and December 2000, records of 1200 children treated consecutively with elective surgery at Komfo Anokye Teaching Hospital in Kumasi, Ghana, were analysed for name, age, sex, postoperative diagnosis, procedure carried out and outcome of treatment

Results:  The ages of the children ranged from 0 to 14 years, with a mean age of 3.5 years (95% confidence interval: 3.3−3.7) with a boy/girl ratio of 3.1:1. Congenital anomalies were the most common problem (83%), followed by tumours (4%), cysts (3%), uncircumcised penis (2%), and lymphadenopathy of varying aetiologies (2%). The most common congenital anomaly was inguinal hernia, and the rarest, biliary atresia. Eighty‐two percent of the children in this series were treated as day‐care cases. Overall mortality in the series was 0.8%.

Conclusions:  The data reviewed here demonstrate that there is a wide range of surgical conditions among children in the developing world. This poses a significant health‐care problem and calls for improved management of such paediatric surgical problems to prevent high morbidity and mortality rates in African children.
A NOTE ON MODELLING SHORT FATIGUE CRACK BEHAVIOUR
Authors: Angelova D , Akid R
Published: March 2003

Based upon experimental short fatigue crack growth data and adopting the Brown–Hobson model, new crack growth equations have been derived in an attempt to describe more precisely short fatigue crack growth behaviour that separates the physically small crack regime from the long crack regime. An empirical model for physically small crack growth was developed by employing elastic–plastic fracture mechanics parameters.

By considering the proposed approach to short fatigue crack modelling, a new second ‘microstructural’ threshold condition has been established using only short fatigue crack growth data. In the case of fatigue in an aggressive environment it is suggested that three transition (threshold) conditions can be identified representing: (i) a stress‐assisted pitting/pit‐to‐crack transition; (ii) a microstructurally short shear crack/physically small tensile crack transition; and (iii) a physically small crack/long crack transition.

A comparison of this approach with that of existing models has been made, and predictions of total fatigue lifetime using the model have been presented. A reasonable agreement has been observed between predicted and experimental crack growth rates.
ANALYSIS OF CAST STEEL FRACTURE MECHANISMS FOR DIFFERENT STATES OF STRESS
Authors: Biel‐ M
Published: March 2003

The process of fracture in a low‐carbon cast steel was studied for different states of stress. As a result of heat treatment, two different microstructures have been obtained: ferritic‐pearlitic and bainitic. The triaxial states of stress were realised by tensile tests on specimens with various notch configurations and on smooth specimens subjected to different hydrostatic pressures.

During tensile tests carried out under triaxial stress states, the following quantities at fracture were determined: the effective strain, effective stress, stress state components, mean stress and stress triaxiality factor. Fractography of the specimens was carried out to observe the fracture mechanisms and relate them to the state of stress. The fracture mechanism depended on the state of stress and microstructure. With a decreasing stress triaxiality factor, the failure mechanism changed from ductile to shear. The fracture mechanism changed across the diameter of the sample and also depended on the microstructure. The small, smooth samples fractured at a higher stress than the larger samples. Ductile fracture in the ferritic‐pearlitic microstructure was controlled by cracking of the matrix–precipitate boundary. Samples with the bainitic microstructure fractured by shear, and fracture depended mainly on the effective stress, although void growth (which is controlled by stress triaxiality) reduced the critical effective stress at positive values of mean stress.
A NEW METHOD FOR PREDICTING FATIGUE LIFE IN NOTCHED GEOMETRIES
Authors: Chien H , Coffin LF
Published: March 2003

The objective of this paper is to develop a notch crack closure model, called NCCM, based on plasticity‐induced effects and short fatigue crack growth in the vicinity of the notch, and to predict the fatigue failure life of notched geometries. By using this model the regime for non‐propagating cracks (n.p.c.) and the relationship between the fatigue strength reduction factor, Kf , and the elastic stress concentration factor, Kt , under mean stress conditions, can be determined quantitatively. A crack closure model is assumed to apply in the notch regime based on an approach developed to explain the crack growth retardation behavior observed in smooth specimen geometries after an overload. Notch plasticity effects are also applied in the NCCM model. Fatigue failure life is calculated from both short fatigue crack growth in the notch region where elastic–plastic fracture mechanics (EPFM) is applied and from long fatigue crack growth remote from the notch where linear elastic fracture mechanics (LEFM) occurs. This prediction is obtained using a quantity called the effective plasticity‐corrected pseudo‐stress. The NCCM can be used to account quantitatively for various observed notch phenomena, including both the relationship between Kf and Kt and n.p.c. The effects of the tensile mean stress on the Kf versus Kt relationship is investigated and leads to the little recognized but technologically important observation that mean stress conditions exist where Kf can be greater than Kt . The role of notch radius and tensile mean stress on n.p.c. behavior is also explored. The model is verified using experimental data for notch geometries of aluminum alloy 2024‐T3, alloy steel SAE 4130 and mild steel specimens tested at zero and tensile mean stress.
LIFE PREDICTION BY SIMULATION OF CRACK GROWTH IN NOTCHED COMPONENTS WITH DIFFERENT MICROSTRUCTURES AND UNDER MULTIAXIAL FATIGUE
Authors: Hoshide T , Kusuura K
Published: March 2003

A modelling procedure was developed which is applicable to crack growth in notched components subjected to multiaxial fatigue for materials with different microstructures. An algorithm for crack growth, in a microstructure that was modelled as hexagons, was established as a competition between growth by crack linkages during the crack initiation and propagation stages and the propagation of a dominant crack as a single crack. Analytical results simulated by using the developed model were compared with experimental results from fatigue tests which had been conducted using notched specimens of pure copper, carbon steel and two kinds of titanium alloy. Cracking morphology, which was experimentally observed to depend on the microstructure and the loading mode, was well simulated using the present model. The fatigue failure life of a notched specimen was statistically estimated by a Monte Carlo procedure based on the model. The simulated life with a statistical scatter‐band almost coincided with the experimental data.
A FIRST STAGE IN THE DEVELOPMENT OF MICROMECHANICAL SIMULATIONS OF THE CRYSTALLOGRAPHIC PROPAGATION OF FATIGUE CRACKS UNDER MULTIAXIAL LOADING
Authors: Doquet V
Published: March 2003

Simulations of the nucleation of dislocations, glide and annihilation ahead of a fatigue crack growing along a localized slip band (a ‘long’ Stage I crack or a Stage II crack with a K value close to the threshold) are performed for the case of push–pull or reversed torsion loadings, ignoring, in a first approach, the effect of grain boundaries. The crack growth rates are deduced from the dislocation flux at the crack tip. An influence of the normal stress on the friction between the crack flanks as well as on the condition for dislocation emission is introduced. A slower Stage I growth rate is then predicted for reversed torsion, consistent with experimental data.
J estimation for shallow semi‐elliptical surface cracks in wide plates under pure bending
Authors: Boothman D. P. , Lee M. M. K. , Luxmoore A. R. , Sumpter J. D.
Published: March 2003

Three‐dimensional finite element models have been used to predict the J versus applied strain behaviour of shallow semi‐elliptical surface cracks in wide steel plates. These models were loaded in pure bending up to fully plastic conditions that produced maximum strains remote from the crack of 10 times the yield strain. This study examined cracks with a crack depth to plate thickness ratio (a/t) in the range 0.05–0.15, and crack depth to crack half‐length ratio (a/c) from 0.2 to 0.57, in elastic‐hardening materials as well as those with a yield plateau before strain‐hardening. The results were found to differ significantly from those obtained from plane strain analyses, and a J estimation scheme was developed from the three‐dimensional results. Comparisons between the results obtained in this work and the J predictions provided by existing defect assessment methods show that the proposed equations are a significant improvement when large strains are likely.
Stress concentrations around bonded repairs
Authors: Vlot  , Verhoeven  , Ipenburg  , Siwpersad  , Woerden
Published: March 2003

Ageing aircraft fuselages require safe and damage‐tolerant repair techniques. Bonded fibre–metal laminates (FML) combine a small mismatch in coefficients of thermal expansion (CTE) with the cracked skin, excellent fatigue properties and high strength, and are therefore promising materials for bonded repairs. This paper focuses on local stress concentrations in the fuselage skin at the edge of a bonded FML repair, and presents analytical, FEM and experimental results of single and multiple repairs in close proximity. Repairs on both flat uniaxially loaded skins and curved biaxially loaded skins were considered. The main objective of this research is the validation of the crack patching design program CalcuRep. The model on which CalcuRep is based, the ‘Rose model’, was extended and used for the analytical prediction of skin stresses in the specimens. It appeared that, in order to prevent fatigue critical stresses in the skin next to the patch, one should carefully choose the patch material and geometry. Furthermore, in a specific repair configuration with multiple patches, a minimum separation is required to prevent high stress concentrations in the skin between the patches. It was confirmed that, in most cases, a biaxial stress field has a favourable effect on the stress in the skin along the patch edge, compared with the uniaxial situation. With both the FEM and the extended Rose model, the stresses in the skin next to the patch could be predicted with sufficient accuracy. It is the intention to implement the extended Rose model in a new version of CalcuRep.
Corrosion fatigue behaviour of a 15Cr‐6Ni precipitation‐hardening stainless steel in different tempers
Authors: Lin C.‐K. , Tsai W.‐J.
Published: March 2003

Systematic fatigue experiments, including both high‐cycle axial fatigue (S–N curves) and fatigue crack growth (FCG, da/dN–ΔK curves), were performed on a precipitation‐hardening martensitic stainless steel in laboratory air and 3.5 wt% NaCl solution. Specimens were prepared in three tempers, i.e. solution‐annealed (SA), peak‐aged (H900) and overaged (H1150) conditions, to characterize the effects of ageing treatment on the corrosion fatigue (CF) resistance. S–N results indicated that fatigue resistance in all three tempers was dramatically reduced by the aqueous sodium chloride environment. In addition, the smooth‐surface specimens in H900 temper exhibited longer CF lives than the H1150 ones, while those in SA condition stood in between. However, for precracked specimens, the H1150 temper provided superior corrosive FCG resistance than the other two tempers. Comparison of the S–N and FCG curves indicated that early growth of crack‐like defects and short cracks played the major role in determining the CF life for smooth surface. The differences in the CF strengths for the S–N specimens of the given three tempers were primarily due to their inherent differences in resistance to small crack growth, as they were in the air environment.
An approach to size effect in fatigue of metals using fractal theories
Authors: CARPINTERI ANDREA , SPAGNOLI A. , VANTADORI S.
Published: March 2003

ABSTRACT As was experimentally observed by several authors, the fatigue strength of metallic materials decreases with increasing the specimen size. Such a decrease can be remarkable for very large structures like, for example, big cargo ships (some hundred meters long) transporting oil or other goods. Size effect in fatigue is herein explained by considering the fractal nature of the reacting cross sections of structures, that is, the renormalized fatigue strength is represented by a force amplitude acting on a surface with a fractal dimension lower than 2, where such a dimensional decrement depends on a self‐similar weakening of the material ligament, owing to the presence of cracks, defects, voids and so forth (microscopic level). However, this decrement tends to progressively disappear with increasing the structure size (macroscopic level), i.e. the effect of the material microstructure on the macroscopic fatigue behaviour gradually vanishes for structures large enough with respect to a characteristic microstructural size, this phenomenon being defined as multifractality. A multifractal scaling law for fatigue limit of metals is proposed, and some experimental results are examined in order to show how to apply the theoretical approach presented.
Microstructures of modified RR2072 single crystal superalloys and their effects on LCF response at 950 8°C
Authors: CHEN Q. Z. , JONES N. , KNOWLES D. M.
Published: March 2003

Effects of microstructural modifications, that are a consequence of adding minor grain boundary strengthening elements (C, Hf), on the fatigue response of an experimental single crystal superalloy have been studied. Investigations show that in the modified alloys, as a consequence of the casting process, the population of pores is reduced, but the average pore size increases and larger pores occur close to the fatigue sample surface. Such porosity changes in the modified alloys are an important contributor to their low cycle fatigue (LCF) properties. At the high stress range of LCF tests undertaken, the growth of cracks initiates from pores and their location in the modified alloys are responsible for decreased fatigue lives. At lower stress ranges, crack initiation consumes a considerable proportion of fatigue life. Since crack initiation involves strain localisation at or near the specimen surface where there is interaction with the environment, the population of pores near the specimen surface and the increased length of the tests plays a significant role in governing fatigue lives. The modified alloys benefit from their lower density of pores in the vicinity of the free surface, and tend to have comparable fatigue lives to that of the base alloy at the lower stress level.
Correlation between cyclic deformation behaviour and microstructure in a duplex steel between 300 and 773 K
Authors: ALVAREZ‐ARMAS I. , ARMAS A. F. , HEREÑÚ S. , DEGALLAIX S. , DEGALLAIX G.
Published: March 2003

Cyclic tests performed in the temperature range 300–773 K on duplex stainless steel DIN 1.4460 show that the cyclic stress–strain behaviour of this steel is strongly temperature dependent. At 300 and 473 K an almost constant peak tensile stress stage, is followed by a slight softening that continues up to failure in the case of 300 K, but by a secondary hardening at 473 K. Pronounced initial cyclic hardening followed by secondary hardening was the main feature of the temperature range between 573 and 723 K. At 773 K, after a weak hardening stage, a strong softening continues up to failure. The mechanical behaviour and the evolution of the microstructure were analysed, and the internal and the effective stresses were studied. It was found that the internal stress is responsible for the strong hardening that occurs in the intermediate temperature range and for the softening at 773 K.
Estimations of creep fracture mechanics parameters for through‐thickness cracked cylinders and finite element validation
Authors: KIM Y.‐J. , HUH N.‐S. , KIM Y.‐J.
Published: March 2003

This paper compares engineering estimation schemes of C* and creep crack opening displacement (COD) for cylinders with circumferential and axial through‐thickness cracks at elevated temperatures with detailed 3D elastic‐creep finite element results. Engineering estimation schemes include the GE/EPRI method; the reference stress (RS) method where the reference stress is defined based on the plastic limit load; and the enhanced reference stress (ERS) method where the reference stress is defined based on the optimised reference load, recently proposed by the authors. Systematic investigations are made not only on the effect of creep‐deformation behaviour on C* and creep COD, but also on effects of the crack location, the cylinder geometry, the crack length and the loading mode. Comparison of the finite element (FE) results with engineering estimations provides that for idealised power law creep, estimated C* and COD rate results from the GE/EPRI method agree best with FE results, suggesting that published plastic influence functions for plastic J and COD for through‐thickness cracked cylinders are reliable. For general creep‐deformation laws where either primary or tertiary creep is important and thus the GE/EPRI method is hard to apply, on the other hand, the ERS method provides more accurate and robust estimations for C* and COD rate than the reference stress method. As these two methods differ only in the definition of the reference stress, the ERS method maintains benefits of the reference stress method in terms of simplicity, but improves accuracy of the estimated J, C* and COD results.
Population and transmission dynamics of cowpox in bank voles: testing fundamental assumptions
Authors: Begon  , Feore  , Bown  , Chantrey  , Jones  , Bennett
Published: March 2003

The idea that the rate of production of new infections, of directly transmitted microparasites, is a reflection of an interaction between the number of infectious hosts and the number of susceptible hosts in a population is central to our understanding of dynamical processes in epidemiology. Empirical support for the idea has been seriously lacking, especially for endemic infections in natural hosts, but is provided here for cowpox virus infection in bank voles (Clethrionomys glareolus), using alternative descriptions of transmission dynamics: true and pseudo mass action. The former appears, overall, to give a better description of the dynamics. Transmission rates differ in two natural populations, but both support previously untested theories on the allometric scaling of transmission rates.
Spatial population dynamics and the design of marine reserves
Authors: Lundberg  , Jonzén
Published: March 2003

The failure of many fisheries world‐wide, and the concern about marine biodiversity, has sparked a growing interest in the spatial aspects of harvested populations. If a population conforms to the Ideal Free Distribution and that one of the habitats is set aside as a reserve free from harvesting, the design of reserves may be problematic. If a substantial proportion of the unharvested population is to be preserved, then the reserve area must be unrealistically large, or have a much higher expected fitness than the unprotected area. Interestingly, the optimal harvest rate will be unaffected by both the size of the reserve and the quality of it relative to the harvested area. Even if the Ideal Free Distribution model is extended to include simple age‐structure and “spillover” of recruits from the reserve, these conclusions largely remain intact. In a model that also includes spillover, the habitat quality of the reserve may also affect the catch.
Life history correlations: why are hymenopteran parasitoids an exception?
Authors: Eijs I.E.M. , Van Alphen J.J.M.
Published: March 2003

This study compares the life histories of five hymenopteran species (genus Leptopilina), and aims to identify reasons why developmental time and life span are not correlated in parasitic Hymenoptera, a relationship that is present in many other taxa. Developmental time, life span, body size, and related traits were measured in female parasitoids that eclosed either from hosts of a standard species or from the host species that are naturally used. Phylogenetic controlled tests revealed that body size was positively correlated with fat reserves, starvation time, and egg load. Developmental time was neither correlated with life span nor correlated to host developmental time. We suggest two mechanisms that affect a potential relationship between developmental time and life span in Leptopilina: (i) delayed emergence in species that live in a stochastic environment (fungi), and (ii) host species related plasticity for growth rates. Additionally, variable adult feeding conditions have large effects on life span measures.
Identifying potential keystone species from field data – an example from temporary ponds
Authors: Fauth J.E.
Published: March 2003

Identifying keystone species is essential for understanding community dynamics and preserving species richness. However, few studies have used quantitative, a priori methods to identify potential keystone species. Species known to act as keystones in North Carolina (NC) temporary ponds (Notophthalmus viridescens, eastern newt, and Siren intermedia, lesser siren) were tested to see whether they played the same role in similar habitats in South Carolina (SC). Newts and sirens had no effect on anuran species richness in SC. Instead, another salamander (Ambystoma talpoideum, mole salamander) absent from the NC ponds was identified as a strong keystone in SC. It functioned independently of environmental factors and the densities of other predators. Larval dragonflies (Tramea carolina, Carolina saddlebag) were identified as weak, context‐dependent keystones in SC, supporting anuran richness in isolated ponds with very low pH. The results suggest that the identity of keystone species varies, even in similar habitats within a physiographic region.
Density dependence in an island population of silvereyes
Authors: McCallum Hamish , Kikkawa Jiro , Catterall Carla
Published: March 2003

The population of silvereyes Zosterops lateralis chlorocephalus, on Heron Island, Great Barrier Reef has been monitored accurately since 1965. Between 1979 and 1993, the breeding success of all birds was determined by monitoring nests. The population fluctuated between 225 and 483 individuals. Four cyclones led to substantial mortality. As this data set is long‐term, has little observation error, and is from an effectively closed population, it provides an unusual opportunity to examine density dependence in reproduction or mortality. Using a stochastic logistic model, we found clear evidence of density dependence in adult population size. Logistic regression suggested that fledgling survival decreased with the numbers of birds attempting to breed. There was also some suggestion that adult survival might be density dependent. The fitted stochastic logistic model predicts negligible risks of extinction for this population, in contrast to the predictions of a published population viability analysis. Whilst our statistical model including density dependence may provide better predictions of the “usual” behaviour of a population than a population viability analysis, we suggest that caution should be exercised when statistically fitted models are used to predict the behaviour of the population at extremes, such as near extinction.
Male–female evolutionary game on mate‐locating behaviour and evolution of mating systems in insects
Authors: Ide J. , Kondoh M.
Published: March 2003

We present a model of a male–female evolutionary game on mate‐locating behaviour. Two major mating systems are considered: “lek polygyny” (in which males aggregate to wait for females searching for males) and “searching polygyny” (in which males search for females emerging or waiting for males). The model predicts that lek polygyny is favoured (i) when male survivorship during lekking is sufficiently higher than that during mate searching, (ii) when female survivorship while visiting a lek is sufficiently higher than at the emergence site, or (iii) when searching efficiency is higher at a lek than at an emergence site. Furthermore, the model shows that a reduction in the reproductive value of females later in the day, which prevents males from performing riskier mate‐locating behaviour, can result in a change of mating system. In addition, mixed mating systems can be realized as transient states during this shift.
Adaptive learning of host preference in a herbivorous arthropod
Authors: Egas Martijn , Sabelis Maurice W.
Published: March 2003

Although many publications deal with the effects of experience on behaviour, adaptive learning (i.e. behavioural change with experience resulting in improved reproductive success) is poorly documented. We present direct evidence that learning of host preference improves fitness in the herbivorous mite, Tetranychus urticae. Individual mites from two strains were repeatedly given a choice between two host plants, tomato and cucumber, and then subjected to a performance test on each. For both strains, food experience affected the subsequent choice: individual mites learned to prefer cucumber over tomato. The performance test showed this effect to be adaptive, as the food plant the mites learned to prefer (cucumber) allowed for increased oviposition, survival and development. These findings have important implications for the interpretation of the preference–performance relationship among herbivorous arthropods. The frequently reported absence of such a relationship may be due to experience‐dependent preference and/or performance.
An abundance–occupancy time‐lag during the decline of an arctiid tiger moth
Authors: Conrad Kelvin F. , Perry Joe N. , Woiwod Ian P.
Published: March 2003

The positive interspecific abundance–occupancy relationship is one of the most general patterns in ecology. Positive intraspecific relationships should also exist within species over time, and so a species should occupy more sites in years when it is more abundant. However, positive intraspecific relationships are not as ubiquitous as their interspecific counterparts. It has been hypothesized that low levels of temporal variation and time‐lags between changes of abundance and occupancy within species make positive intraspecific relationships difficult to detect. We analyse 31 years of U.K.‐wide data on the decline of an arctiid moth, Arctia caja, which provides the first empirical demonstration of an abundance–occupancy time‐lag for any species. Such time‐lags are probably common and we discuss their impact on the intraspecific abundance–occupancy relationship and their implications for conservation management. In A. caja, the time‐lag indicates that the decline of the species is probably not driven by habitat loss.