bluuebunny/crossref_metadata_2025 huggingface dataset:
Umbilical artery aneurysm: prenatal identification in three fetuses with trisomy 18
Authors: Sepulveda W. , Corral E. , Kottmann C. , Illanes S. , Vasquez P. , Monckeberg M. J.
Published: March 2003

Aneurysm of the umbilical artery is an extremely rare anomaly of the umbilical cord, with only two cases being documented in the English language literature. We report three cases diagnosed prenatally by ultrasound in the third trimester, all associated with single umbilical artery and multiple structural fetal anomalies. Prenatal karyotyping revealed trisomy 18 in all three cases. Umbilical cord anomalies, although rare, are associated with significant fetal morbidity and mortality. This report identifies umbilical artery aneurysm as an additional prenatal feature of trisomy 18. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Prenatal diagnosis of sustained bradycardia with 1 : 1 atrioventricular conduction
Authors: Maeno Y. , Rikitake N. , Toyoda O. , Kiyomatsu Y. , Miyake T. , Himeno W. , Hirose A. , Hori D. , Kamura T. , Kato H.
Published: March 2003

Objectives

The aims of this study were to elucidate the clinical course of fetal bradycardia with 1 : 1 atrioventricular conduction, and to discuss the optimal management of affected fetuses in the second and third trimesters of pregnancy.

Methods

The hospital records of five fetuses with the diagnosis of bradycardia (100 bpm) with 1 : 1 atrioventricular conduction between 1981 and 2000 in our institution were reviewed. Atrioventricular conduction was evaluated by simultaneous M‐mode echocardiographic tracing of the atria and the ventricles.

Results

The gestational ages at referral ranged from 19 to 36 (median, 25) weeks, and fetal heart rates ranged from 60 to 80 (median, 80) bpm. Postnatal electrocardiography revealed sinus bradycardia in four (two of which were siblings) of the five cases, and junctional rhythm in the remaining case. Two fetuses with congenital heart defects (CHDs) were delivered by Cesarean section but died postnatally. The three fetuses without CHDs were delivered vaginally and have survived to date for 6, 8 and 15 years.

Conclusions

Fetal bradycardia with 1 : 1 atrioventricular conduction caused by sustained sinus bradycardia or wandering pacemaker is an important type of fetal arrhythmia. Further investigations with a larger number of cases are required to determine the risk factors for predicting the outcome of affected fetuses. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
The contribution of transvaginal ultrasound in the diagnosis of acute appendicitis: an observational study
Authors: Caspi B. , Zbar A. P. , Mavor E. , Hagay Z. , Appelman Z.
Published: March 2003

Objective

To assess the contribution of transvaginal and transabdominal sonography in the diagnosis of acute appendicitis.

Methods

The study group included female patients in whom acute appendicitis was diagnosed preoperatively by ultrasound and confirmed by histology. Each patient was examined by transabdominal (TAS) and transvaginal (TVS) sonography. The contribution of both approaches to the diagnosis of acute appendicitis was assessed.

Results

Acute appendicitis was diagnosed sonographically in 38 women. In all of them the diagnosis was confirmed histologically. All patients had both TAS and TVS. In 16 (42%) patients the inflamed appendix was detected by both approaches, in 13 (34%) only by the transabdominal route and in nine (24%) only transvaginally. Thus, TAS detected only 76% of the cases and TVS added 24%.

Conclusion

The use of TVS in conjunction with TAS seems to improve the detection rate of acute appendicitis. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Isolated fetal ascites caused by Wolman disease
Authors: Ben‐Haroush A. , Yogev Y. , Levit O. , Hod M. , Kaplan B.
Published: March 2003

Wolman disease is a rare autosomal‐recessive disorder caused by reduced levels of lysosomal acid lipase. It occurs in infancy and is fatal in most cases before the age of 1 year. Affected infants show signs of lipid storage in most tissues, including hepatosplenomegaly, abdominal distension, vomiting, steatorrhea, failure to thrive, and adrenal calcifications. We present a case of isolated fetal ascites diagnosed at 32 weeks of gestation, with negative work‐up for immune and non‐immune hydrops fetalis and congenital infections and malformations. After delivery, the diagnosis of Wolman disease was established. Although rare, storage diseases such as Wolman disease should be considered in cases of isolated fetal ascites. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Minimal invasive complete excision of benign breast tumors using a three‐dimensional ultrasound‐guided mammotome vacuum device
Authors: Baez E. , Huber A. , Vetter M. , Hackelöer B.‐J.
Published: March 2003

Objective

The aim of this study was to evaluate the use of three‐dimensional (3D) ultrasonography in the complete excision of benign breast tumors using ultrasound‐guided vacuum‐assisted core‐needle biopsy (Mammotome®). A protocol for the management of benign breast tumors is proposed.

Method

Twenty consecutive patients with sonographically benign breast lesions underwent 3D ultrasound‐guided mammotome biopsy under local anesthesia. The indication for surgical biopsy was a solid lesion with benign characteristics on both two‐dimensional (2D) and 3D ultrasound imaging, increasing in size over time or causing pain or irritation. Preoperatively, the size of the lesion was assessed using 2D and 3D volumetry. During vacuum biopsy the needle was visualized sonographically in all three dimensions, including the coronal plane. Excisional biopsy was considered complete when no residual tumor tissue could be seen sonographically. Ultrasonographic follow‐up examinations were performed on the following day and 3–6 months later to assess residual tissue and scarring.

Results

All lesions were histologically benign. Follow‐up examinations revealed complete excision of all lesions of < 1.5 mL in volume as assessed by 3D volumetry. 3D ultrasonographic volume assessment was more accurate than 2D using the ellipsoid formula or assessment of the maximum diameter for the prediction of complete excision of the tumor. No bleeding or infections occurred postoperatively and no scarring was seen ultrasonographically on follow‐up examinations.

Conclusions

Ultrasound‐guided vacuum‐assisted biopsy allows complete excision of benign breast lesions that are ≤1.5 mL in volume (calculated by 3D volumetry), and thus avoids open surgery and postoperative scarring. Under local anesthesia it is a safe procedure with optimal compliance. 3D ultrasound offers the advantage of better preoperative demonstration of the lesions' margins, resulting in better assessment of volumetry, improved intraoperative needle location and perioperative identification of residual tumor tissue. 3D sonographically guided biopsy should be integrated into breast cancer screening programs as a safe therapeutic option for breast lesions presumed to be benign. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Fetal thoracoamniotic shunting as the only treatment for pulmonary sequestration with hydrops: favorable long‐term outcome without postnatal surgery
Authors: Salomon L. J. , Audibert F. , Dommergues M. , Vial M. , Frydman R.
Published: March 2003

Although it is established that bronchopulmonary sequestration complicated by fetal hydrops carries a high risk of perinatal mortality, prenatal management remains controversial. Therapeutic options include immediate delivery, medical therapy based on an inotropic regimen, alcohol ablation of the vascular pedicle, open fetal surgery, or thoracoamniotic shunting of fetal pleural effusions. We report a case of pulmonary sequestration with hydrothorax and fetal hydrops which was successfully treated by a single fetal thoracoamniotic catheter drainage. Following emergency catheter placement, hydrothorax and hydrops decreased dramatically. The sequestration gradually disappeared postnatally, and long‐term outcome remained normal without any postnatal therapy. Based on this observation, the natural history of pulmonary sequestration and prenatal management options are reviewed. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Editorial
Authors: JONES CLIFF
Published: March 2003

Professor Edsger W. Dijkstra has had a profound effect on many aspects of Computer Science. His death will
leave a huge gap in our scientific world. The personal loss to those who had the privilege of knowing Edsger
is even larger. Edsger was not always the easiest of colleagues: he held strong opinions and rarely hid them.
His exacting scientific standards have had an enormous impact on computing science. Edsger's writings have
shaped and will continue to influence our subject. Those who worked closely with him and have taken up his
methods and ideas will continue to be heard.
This edition of Formal Aspects contains a wonderfully insightful memorial written by Krzysztof Apt. In
his balanced obituary, Apt refers to the famous “EWD” reports whose contribution we reflect by printing one
that has not previously been published: we are grateful to Ria Dijkstra for permission to so do and for help
from Ham Richards (Ham was also behind the lens for the evocative photograph of Edsger). Many EWDs
were circulated as copies of Edsger's clear handwriting and although EWD1300 is printed here in typescript,
a complete library in Edsger's hand is available at http://www.cs.utexas.edu/users/EWD/
Edsger Wybe Dijkstra (1930–2002): A Portrait of a Genius
Authors: Apt Krzysztof R.
Published: March 2003

Edsger Wybe Dijkstra was born in Rotterdam on 11 May 1930. His mother was a mathematician and father
a chemist. In 1956 he graduated from the University of Leiden in mathematics and theoretical physics. In
1959 he received his PhD from the University of Amsterdam for his thesis entitled ‘Communication with an
Automatic Computer’, devoted to a description of the assembly language designed for the first commercial
computer developed in the Netherlands, the X1. It also dealt with the concept of an interrupt, a novelty at
that time. His PhD thesis supervisor was Aad van Wijngaarden.
EWD1300: The Notational Conventions I Adopted, and Why
Authors: Dijkstra Edsger W.
Published: March 2003

At a given moment, the concept of polite mathematics emerged, the underlying idea of which is that, even if you have only 60 readers, it pays to spend an hour if by doing so you can save your average reader a minute. By inventing an idealized ‘average reader’, we could translate most of the lofty, human goal of politeness into more or less formal criteria we could apply to our texts. This note is devoted to the resulting notational and stylistic conventions that were adopted as the years went by.
We don't want to baffle or puzzle our reader, in particular it should be clear what has to be done to check our argument and it should be possible to do so without pencil and paper. This dictates small, explicit steps. On the other hand it is well known that brevity is the leading characteristic of mathematical elegance, and some fear that this ideal excludes the small, explicit steps, but one of the joys of my professional life has been the discovery that this fear is unfounded, for brevity can be achieved without committing the sin of omission.
I should point out that my ideal of crisp clarity is not universally shared. Some consider the puzzles that are created by their omissions as spicy challenges, without which their texts would be boring; others shun clarity lest their work is considered trivial.
Generic Composition
Authors: Chen Yifeng
Published: March 2003

This paper presents a technique called
generic composition
to provide a uniform basis for modal operators, sequential composition, different kinds of parallel compositions and various healthiness conditions appearing in a variety of semantic theories. The weak inverse of generic composition is defined. A completeness theorem shows that any predicate can be written in terms of generic composition and its weak inverse. A number of algebraic laws that support reasoning are derived.
A Refinement Calculus for Shared-Variable Parallel and Distributed Programming
Authors: Dingel J.
Published: March 2003

Parallel computers have not yet had the expected impact on mainstream computing. Parallelism adds a level of complexity to the programming task that makes it very error-prone. Moreover, a large variety of very different parallel architectures exists. Porting an implementation from one machine to another may require substantial changes. This paper addresses some of these problems by developing a formal basis for the design of parallel programs in the form of a refinement calculus. The calculus allows the stepwise formal derivation of an abstract, low-level implementation from a trusted, high-level specification. The calculus thus helps structuring and documenting the development process. Portability is increased, because the introduction of a machine-dependent feature can be located in the refinement tree. Development efforts above this point in the tree are independent of that feature and are thus reusable. Moreover, the discovery of new, possibly more efficient solutions is facilitated. Last but not least, programs are correct by construction, which obviates the need for difficult debugging. Our programming/specification notation supports fair parallelism, shared-variable and message-passing concurrency, local variables and channels. The calculus rests on a compositional trace semantics that treats shared-variable and message-passing concurrency uniformly. The refinement relation combines a context-sensitive notion of trace inclusion and assumption-commitment reasoning to achieve compositionality. The calculus straddles both concurrency paradigms, that is, a shared-variable program can be refined into a distributed, message-passing program and vice versa.
p53 and mdm-2 Expression in Rhabdomyosarcoma of Childhood and Adolescence: Clinicopathologic Study by the Kiel Pediatric Tumor Registry and the German Cooperative Soft Tissue Sarcoma Study
Authors: Leuschner Ivo , Langhans Inken , Schmitz Regina , Harms Dieter , Mattke Adrian , Treuner Jörn
Published: March 2003

Rhabdomyosarcomas (RMS) are the most common malignant soft tissue sarcomas in childhood and adolescence. Despite a large number of publications about this heterogeneous group of tumors, little is known about proliferation, p53 and mdm-2 in relation to histological subtype, clinical parameter, and prognosis of patients. We studied 150 cases of RMS treated in the German Cooperative Soft Tissue Sarcoma Study (CWS) by immunohistochemistry on paraffin-embedded tissue, using antibodies against p53, mdm-2, and Ki-67. The results were correlated with histological subtype, mitotic count, and various clinical parameters. Both p53 and mdm-2 were expressed at low levels and did not show differences between embryonal and alveolar RMS. Tumors of patients with metastatic embryonal RMS showed significantly higher levels of p53 protein than nonmetastatic tumors. This might be a clue to an important role of p53 in metastatic embryonal RMS. Nevertheless, neither p53 nor mdm-2 showed any correlation to prognosis. Proliferation measured by Ki-67 immunostaining (KiS5 antibody) or mitotic count did not show significant differences between embryonal and alveolar RMS. In addition, these parameters did not correlate with response to therapy or prognosis. In conclusion, we could not demonstrate that any of the investigated parameters had an influence on prognosis of RMS. p53 protein over-expression might be a crucial step in metastatic disease for patients with embryonal RMS.
Soft Tissue Perineuromas in Children: Report of Three Cases and Review of the Literature
Authors: Balarezo Fabiola S. , Muller Richard C. , Weiss Richard G. , Brown Timothy , Knibbs David , Joshi Vijay V.
Published: March 2003

Perineuromas (PN) are uncommon, slowly growing, usually benign tumors composed of well-differentiated perineural cells. Two variants are recognized: intraneural perineuromas and soft tissue perineuroma, which includes a sclerosing subset of tumors. They are usually reported in the adult population. We present three cases of soft tissue perineuromas in children. One was located in the deep soft tissue of the retroperitoneum in a 14-year-old girl, the second one in the left thumb of a 14-year-old boy, and the third one in the index finger of a 16-year-old boy. This report, which describes the clinicopathologic, immunohistochemical, and ultrastructural features of these tumors, should alert pathologists to the occurrence of perineuromas in children. A review of the English language literature on perineuromas in children is also included.
Cerebral Malignant Nerve Sheath Tumor, Triton Tumor Variant: Case Report
Authors: Bornstein-Quevedo Leticia , Peralta-Olvera Fabiola , Marhx-Bracho Alfonso , Rodríguez-Jurado Rodolfo , de Leon-Bojorge Beatriz
Published: March 2003

A case of a cerebral malignant triton tumor in a 3-year-old boy with a 2-month history of frontal headache and no clinical evidence of neurofibromatosis is reported. The computed tomography (CT) scan showed a large, irregular tumor in the right parietooccipital lobe. A partial surgical resection was performed. Histologically, the tumor was highly cellular and consisted of spindle cells with hyperchromatic and pleomorphic nuclei. Focally, neoplastic cells with rhabdomyoblastic features were found. The immunohistochemical study showed that tumor cells were positive for S-100 protein and CD57, and the rhabdomyoblasts expressed desmin, Myo-D1, and myoglobin. During the postoperative period, a massive intraparenchymal hemorrhage was identified and surgical drainage was performed. The patient worsened and died 10 days after the first surgery. Postmortem study was not authorized. Six cases of cerebral malignant nerve sheath tumor have been described; however, primary intraparenchymal malignant triton tumor has not been previously described.
Aggressive Angiomyxoma of Childhood: Two Unusual Cases Developed in the Scrotum
Authors: Kim Han-Seong , Park Sung-Hye , Chi Je Geun
Published: March 2003

Aggressive angiomyxoma (AAM) is a locally invasive soft tissue tumor and is predominantly found in the female pelvis and perineum. The incidence of AAM in adult and adolescent males is low, and is very rare in male children. However, two cases of AAM occurred in the scrotum of 8-year-old and 1-year-old boys. Grossly, both tumors were ill-delineated nodules showing myxoid homogenous and lobulated cut surface. The scrotum of case 2 was replaced by the exuberant mass, making a polypoid appearance. On microscopic examination, both had hypocellular myxoid stroma, spindle and stellate stromal cells, and blood vessels of various calibers. Both lesions typically showed infiltrating borders and penetrated into skin adnexa and Dartos' muscle fibers. AAM should be considered in the differential diagnosis of a scrotal mass found in childhood.
Incidence of Autopsy Findings in Unexpected Deaths of Children and Adolescents
Authors: Parham David M. , Savell Van H. , Kokes Charles P. , Erickson Stephen A. , Peretti Frank J. , Gibson James B. , Sturner William Q.
Published: March 2003

Studies in various settings reveal that a significant percentage of autopsies demonstrate findings that were not previously clinically diagnosed. In the pediatric and adolescent age group, forensic examinations comprise a large percentage of total autopsies performed. We hypothesized that a similar number of previously undiagnosed findings would be present in this population and thus reviewed a series of autopsy reports from the Medical Examiners Office in the Arkansas Crime Laboratory. During 1997 through 1999, we performed 439 complete forensic autopsies on children and adolescents (age range 1 day to 19 years; median 18 months). Previously undiagnosed lesions were found in 173 (39%). Of these subjects, 68 (39%) had clinically significant pathology, 60 (35%) had insignificant pathology, and 45 (26%) had pathology of undetermined significance. Thirty-six subjects had lesions expected from a previously diagnosed condition. Of the total number of lesions found, 168 were inflammatory, 58 were congenital anomalies (48 unexpected), and 88 comprised miscellaneous other conditions. Infants < 6 months of age were significantly more likely to have a previously undiagnosed lesion than children > 6 months ( P < 0.0001). Previously undiagnosed findings, mostly inflammatory, occur relatively frequently in pediatric and adolescent forensic autopsies and are more likely to occur in infants.
Primary Burkitt-like Lymphoma Presenting as a Solitary Rectal Polyp in a Child: Case Report
Authors: Zhang Xinmin , Beneck Debra , Bostwick Howard E. , Weisberger James
Published: March 2003

Primary rectal lymphoma in childhood is rare. We report a case in a 10-year-old boy who presented with rectal bleeding and a single rectal polyp. Histologic examination, immunophenotyping and molecular genetic study of the polyp showed a diffuse B-cell lymphoma, Burkitt-like type. The literature on this topic is reviewed and pathologic examination of childhood rectal polyps is emphasized.
Adenovirus Ascending Cholangiohepatitis
Authors: Bründler Marie-Anne , Rodriguez-Baez Norberto , Jaffe Ron , Weinberg Arthur G. , Rogers Beverly Barton
Published: March 2003

Three children, two with liver transplants and one with acquired human immunodeficiency virus (HIV) infection, presented with hepatitis accompanied by elevated gamma glutamyl transpeptidase. Biopsies revealed cholangiohepatitis caused by adenovirus infection. There was a progressive loss of interlobular bile ducts in two of the patients. In one patient, infection of the biliary tree was marked by a necrotizing cholangitis, with adenoviral inclusions noted in the biliary epithelium. In each patient, there was evidence of adenovirus gastrointestinal infection. This is the first report of adenoviral infection of the biliary tree in humans. It is hypothesized that adenovirus cholangiohepatitis occurs as a result of ascending infection from the gastrointestinal tract to the biliary tree.
Sudden Infant Death Syndrome: Overview and Update
Authors: Byard Roger W. , Krous Henry F.
Published: March 2003

The past decade and a half has seen marked changes in the epidemiology of sudden infant death syndrome (SIDS). The avoidance of certain risk factors such as sleeping prone and cigarette smoke exposure has resulted in the death rate falling dramatically. Careful evaluation of environmental factors and endogenous characteristics has led to a greater understanding of the complexities of the syndrome. The development and implementation of death scene and autopsy protocols has led to standardization in approaches to unexpected infant deaths with increasing diagnoses of accidental asphyxia. Despite these advances, there is still confusion surrounding the diagnosis, with deaths being attributed to SIDS in many communities and countries where death scene investigations and autopsies have not been conducted. The following review provides a brief overview of the historical background, epidemiology, pathology, and pathogenesis of SIDS. Contentious issues concerning the diagnosis and current problems are discussed. Despite calls to abandon the designation, SIDS remains a viable term for infants who die in their sleep with no evidence of accident, inflicted injury, or organic disease after a full investigation has been conducted according to standard guidelines.
Reference Values for Second Trimester Fetal and Neonatal Organ Weights and Measurements
Authors: Hansen Katrine , Sung C. James , Huang Carol , Pinar Halit , Singer Don B. , Oyer Calvin E.
Published: March 2003

To establish accurate reference ranges for the entire second trimester, we documented organ weights, body weight, and linear measurements for 597 fetuses and neonates with gestational ages ranging from 12 to 26 wk. We determined the mean and standard deviation for weights and measurements at each week of gestation using the StatView™ SE + Graphics statistical program. The analyses revealed a linear correlation between the gestational age and, respectively, the toe-heel length, crown-rump length, and crown-heel length. Body and organ weights increase at varying rates throughout the second trimester. The data correlate well with weights and measurements previously published for the latter half of the second trimester, and extend these reference ranges to encompass the entire second trimester.
Classic Adamantinoma with Osteofibrous Dysplasia-like Foci and Secondary Aneurysmal Bone Cyst
Authors: Putnam Angelica , Yandow Suzanne , Coffin Cheryl M.
Published: March 2003

Adamantinoma, a rare bone lesion of the tibia and fibula, has two distinct variants, classic adamantinoma and osteofibrous dysplasia-like adamantinoma. Composite lesions have not been described. Aneurysmal bone cyst is a benign cystic lesion which may also occur in the tibia and fibula. We report an unusual case of classic adamantinoma with osteofibrous dysplasia-like areas and foci of secondary aneurysmal bone cyst with prominent giant cells. A lesion was diagnosed in a 17-year-old girl with a 14-year history of a slowly enlarging left tibial mass and increasing deformity. Pathologically, the predominant pattern was classic adamantinoma, with minor foci of osteofibrous dysplasia-like adamantinoma and areas of secondary aneurysmal bone cyst with abundant multinucleated giant cells. We report the clinical, radiologic, and pathologic features of this case, and summarize lesions associated with secondary aneurysmal bone cyst. To our knowledge, the association of adamantinoma with secondary aneurysmal bone cyst has not been previously reported.
Giant Botryoid Fibroepithelial Polyp of Bladder with Myofibroblastic Stroma and Cystitis Cystica et Glandularis
Authors: Al-Ahmadie Hikmat , Gomez Ana M. , Trane Nicholas , Bove Kevin E.
Published: March 2003

A 3-year-old boy presented with a single episode of gross hematuria and no history of previous urinary tract disorder. Imaging studies revealed a large complex polypoid filling defect in the bladder lumen. Several attempts at transurethral biopsy and cytological examination of the urine revealed clumps of benign epithelial cells, but suspicion of a malignant neoplasm such as rhabdomyosarcoma remained high and the lesion was resected. The specimen measured 15 cm, had a narrow zone of attachment to the bladder mucosa, and was grossly botryoid. Changes typical of cystitis cystica et glandularis were present at and near all surfaces. Myxoid stroma contained scattered benign fibroblasts, myofibroblasts, and smooth muscle cells. Inexplicably, one of two karyotyped stromal cells demonstrated a translocation usually associated with rhabdomyosarcoma. This child is well without evidence of bladder abnormality 1.5 years after surgery.
Dynamic interaction between a leaf beetle, Galerucella nipponensis, and an aquatic plant, Trapa japonica. II. Dispersal behavior of larvae
Authors: Tanaka M. , Nakasuji F.
Published: March 2003

The dispersal behavior of the larvae of a leaf beetle, Galerucella nipponensis, was investigated to analyze the dynamic interaction between the leaf beetle and its aquatic host plant, Trapa japonica. The hatchlings dispersed from the hatched leaf to other leaves in a rosette within 12 h. Some larvae even dispersed on the water surface. As a result, the hatchlings distributed uniformly within the rosette. This larval dispersal appeared to be adaptive behavior responding to a rapid turnover of T. japonica leaves. The female adults preferred young or middle‐aged leaves to old leaves as oviposition sites.
Genetic risk involved in stock enhancement of fish having environmental sex determination
Authors: Kanaiwa M. , Harada Y.
Published: March 2003

Environmental sex determination is reported in various fish species, including some fishes subject to stock enhancement. We studied the influence of stock enhancement on the sex‐determining system of fish with both genotypic and environmental sex determination. We constructed and analyzed recurrence formula models for the dynamics of gene frequency in the male heterogametic (XX female and XY male) sex‐determining system of the Japanese flounder (Paralichthys olivaceus). In this species, an XX individual can develop as a phenotypic male (sex‐reversed male) depending on the conditions experienced by a juvenile. We show that the release of sex‐reversed males may result in the extinction of the Y gene that determines sex. We also studied how the risk depends on the kind of hatchery broodstock used (e.g., fish collected from the wild or fish from a lineage established in a hatchery), sex‐reversal rates in the hatchery and in the wild, and the relative contribution of released fish to reproduction in the wild. We propose some ways to reduce the risk.
Latitudinal trends in adult body size of Dolly Varden, with special reference to the food availability hypothesis
Authors: Maekawa K. , Nakano S.
Published: March 2003

The food availability hypothesis (FAH) predicts that the relative productivity of ocean and freshwater habitats changes with latitude, and that anadromy will evolve when ocean productivity is greater than that in neighboring freshwater habitats, or vice versa. In data sets for the anadromous salmonid species Salvelinus malma, we show that the relative body size at maturity of anadromous populations is much larger in the northern limits of their ranges than that of fluvial populations, and, conversely, that of fluvial populations is slightly smaller at the southern limits than that of anadromous populations, supporting the FAH for the evolution of migration behavior in salmonids.
Factors affecting refuge from parasitoid attack in a cynipid wasp, Aphelonyx glanduliferae
Authors: Ito M. , Hijii N.
Published: March 2003

We examined seasonal patterns of gall morphology, growth, and survivorship of the agamic generation of a cynipid wasp, Aphelonyx glanduliferae, and discussed its mortality factors, especially from the point of view of refuge from parasitoid attack. Although the initiation period varied greatly among individual galls, the larvae of A. glanduliferae grew rapidly and reached their maximum size within 3 weeks before pupating in late September to early October. This growth period corresponded to the period when the gall walls became thinner. Parasitoid attack, which was the principal factor in the mortality of A. glanduliferae in the tree crown, was concentrated around the pupation period of the cynipid. Gall walls were significantly thinner in galls attacked by parasitoids than in those still containing a living cynipid. Therefore, the period available to parasitoids seems to be limited by both gall wall thickness and cynipid size. Thus, the growth pattern of A. glanduliferae larvae can have significance in that it narrows the window of vulnerability to parasitoids to a particular period. Although delaying gall initiation will also shorten the exposure period to parasitoid attacks, it was likely to increase the risk of death from gall abortion caused by seasonal degradation in the quality of host plant tissues. Although many cynipids were killed by disease in the galls that fell to the ground, the falling of mature galls to the ground may be another way to a parasitoid‐free space. It is thus suggested that a trade‐off among life history traits against multiple factors operates in the refuge of A. glanduliferae from parasitoid attack.
Biodiversity and stability of herbivore populations: influences of the spatial sparseness of food plants
Authors: Yamamura K.
Published: March 2003

Returning to the classical diversity–stability problem about population densities, we propose a hypothesis that the spatial sparseness of food plants of herbivores, which is frequently observed in diversified communities such as those in the tropics, may be a potential source of the low variability in herbivore densities. The hypothesis consists of the following components: (1) sparseness of food plants of several herbivores increases with increasing number of plant species in a given amount of area, (2) spatial sparseness of food plants reduces the dispersal rate of herbivores between food plants, (3) such a decrease in dispersal rate causes a larger spatial variance in the consumption rate of food plants, (4) such a large spatial variance in the consumption rate of food plants reduces the temporal variance in the amount of food plants, and (5) the reduced temporal variance in the amount of food plants yields a smaller variance in the temporal dynamics of herbivores. A simple mathematical model was constructed to show a theoretical basis of the fourth component of the hypothesis. To exemplify the second, third, and fourth components of the hypothesis in fields, we conducted field experiments on the interaction between butterfly larvae and cabbages, in which cabbage seedlings were planted by two levels of sparseness: 1 m apart and 0.2 m apart. The spatial variance in the amount of leaf dry weight that escaped from larval feeding was larger in sparsely planted fields, which was in accordance with the third component of the hypothesis. The variability in the mean amount of leaf dry weight was smaller in sparsely planted fields, which was in accordance with the fourth component of the hypothesis.
Spatial structure‐mediated indirect effects of an aquatic plant, Trapa japonica, on interaction between a leaf beetle, Galerucella nipponensis, and a water strider, Gerris nepalensis
Authors: Ikeda K. , Nakasuji F.
Published: March 2003

The spatial structure‐mediated indirect effects of an aquatic host plant, Trapa japonica (Trapaceae), on survival of a leaf beetle, Galerucella nipponensis (Coleoptera: Chrysomelidae), with regard to predation by a water strider, Gerris nepalensis (Hemiptera: Gerridae), were investigated in an irrigation pond and under indoor conditions. Beetle density, particularly in the first‐instar stage of the larvae, became extremely low in the second generation in the pond, even though food resources were abundant. The biological check method, which excludes natural enemies by caging, suggested that a causal factor of the low density was predation by Gerris nepalensis in midsummer and thereafter. Normally growing rosettes extend their leaves horizontally on the water surface. However, some rosettes of T. japonica grew leaves vertically in the later seasons, and such overgrown rosettes were distributed patchily in the ponds. Beetle density was higher on the latter rosettes than on the former ones. The indoor experiment showed that the water strider can feed on the eggs of beetles on normally grown rosettes but not on the overgrown rosettes. Furthermore, female adults of Galerucella nipponensis preferred the overgrown rosettes over the normally grown rosettes for oviposition when water striders were present. These facts suggest that the spatial structure‐mediated indirect effects of the host plant modify the interaction between herbivore and predator.
Fixation probabilities in a spatially heterogeneous environment
Authors: Gavrilets S. , Gibson N.
Published: March 2003

We consider a simple model of a one‐locus, two‐allele population inhibiting a two‐patch system and experiencing spatially heterogeneous viability selection. The populaton size is finite. We use a diffusion approximation and singular perturbation techniques to find the probability of fixation of a mutant allele. We focus on situations in which each allele is advantageous in one patch and deleterious in the other patch. Our theoretical results support the previous conclusions that, under certain conditions, small populations respond faster to selection than do large populations. We emphasize that knowledge of the dependence of migration rates on population size is crucial in evaluating the effects of population size on the rate of evolution.
A model for the evolutionary dynamics of cross‐feeding polymorphisms in microorganisms
Authors: Doebeli M.
Published: March 2003

Understanding mechanisms of evolutionary diversification is central to evolutionary biology. Microbes constitute promising model systems for observing processes of diversification directly in the laboratory. One of the main existing paradigms for microbial diversification is the evolution of cross‐feeding polymorphisms, in which a strain specializing on a primary resource coexists with a cross‐feeding strain that specializes on a waste product resulting from consumption of the primary resource. Here I propose a theoretical model for the evolutionary dynamics through which cross‐feeding polymorphisms can gradually emerge from a single ancestral strain. The model is based on the framework of adaptive dynamics, which has proved to be very useful for studying adaptive processes of divergence under sympatric conditions. In particular, the phenomenon of evolutionary branching serves as a general paradigm for diversification. I show that evolutionary branching naturally occurs in evolutionary models of cross‐feeding if (1) there is a trade‐off between uptake efficiencies on the primary and secondary resources, and (2) this trade‐off has positive curvature. The model also suggests that the evolution of cross‐feeding should be more likely in chemostat cultures than in serial batch cultures, which conforms with empirical observations. Overall, the model provides a theoretical metaphor for the evolution of cross‐feeding polymorphisms.
Symbiotic sympatric speciation: consequence of interaction‐driven phenotype differentiation through developmental plasticity
Authors: Kaneko K.
Published: March 2003

A mechanism of sympatric speciation is presented based on the interaction‐induced developmental plasticity of phenotypes. First, phenotypes of individuals with identical genotypes split into a few groups, according to instability in the developmental dynamics that are triggered with the competitive interaction among individuals. Then, through mutational changes in the genes, the phenotypic differences are fixed to genes, until the groups are completely separated in genotype as well as phenotype. It is also demonstrated that the proposed theory leads to hybrid sterility under sexual recombination, and thus speciation is completed in the sense of reproductive isolation. As a result of this postmating isolation, the mating preference evolves later. When there are two alleles, the correlation between alleles is formed to consolidate speciation. When individuals are located apart in space, different species are later segregated spatially, implying that the speciation so far regarded to be allopatric may be a result of sympatric speciation. Relationships to previous theories, frequency‐dependent selection, reinforcement, Baldwin's effect, phenotypic plasticity, and resource competition are briefly discussed. Relevance of the results to natural evolution is discussed, including punctuated equilibrium, incomplete penetrance in mutants, and the change in flexibility in genotype–phenotype correspondence. Finally, we discuss how our theory is confirmed both in the field and in the laboratory, in an experiment using Escherichia coli.
Polygenic inheritance is not necessary for sympatric speciation by sexual selection
Authors: Takimoto G.
Published: March 2003

The theoretical possibility of sympatric speciation by sexual selection has been demonstrated by a number of mathematical models. Although these models assumed that sexually selected traits are additively determined by many genes, recent empirical studies suggest that many sexually selected traits are determined by major gene inheritance. Thus, using a mathematical simulation model, this article examines whether sympatric speciation by sexual selection can occur when sexually selected traits are determined by major gene inheritance. The model reveals that speciation can occur with major gene inheritance of sexually selected traits. Simulations show that speciation from an initially monomorphic population occurs via two successive Fisher's runaway processes of sexual selection. The first runaway causes the unidirectional evolution of male secondary sexual character toward one extreme in the trait space and of female mate preference for such a character. The second runaway then drives the male character and female preference of a part of the population toward the other extreme in the trait space, splitting the population into two reproductively isolated subgroups. The current results reinforce the plausibility of sympatric speciation by sexual selection.
Dispersal distance of heterogeneous populations
Authors: Yamamura K.
Published: March 2003

Heterogeneity among individuals in a population is one of the important factors that influence the rate of population spread. To incorporate the population heterogeneity into dispersal rate, we assume that the traveling duration varies following a gamma distribution with a shape parameter k, where (1/k) indicates the heterogeneity in the traveling duration. The resultant distribution of the traveling distance, which is called dispersal function, is then expressed by using a modified Bessel function of the second kind of order (k − 1). It is shown that the front of the distribution spreads with time in an accelerated manner during an early phase of expansion if the heterogeneity is sufficiently large, which is consistent with the results from previous studies of biological invasions. By using the data obtained from mark–recapture experiments using traps, we can obtain the maximum likelihood estimates of three parameters: heterogeneity in the traveling duration, which is defined by (1/k); the mean dispersal ability, which is defined by the product of the diffusion coefficient and the mean traveling duration; and the trap efficiency. The usefulness of this model is shown by using the data of mark–recapture experiments with the common cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae).
Population dynamics of a thistle‐feeding lady beetle Epilachna niponica (Coccinellidae: Epilachninae) in Kanazawa, Japan. 1. Adult demographic traits and population stability
Authors: Koji S. , Nakamura K.
Published: March 2003

Population dynamics of a thistle‐feeding univoltine lady beetle, Epilachna niponica Lewis (Coleoptera: Coccinellidae), was studied from 1996 to 1999 in Yuwaku, Kanazawa, Japan. The lady beetles often reached such a high density level that food was depleted. The Jolly–Seber method was used for adult marking, release, and recapture data to estimate population parameters of adult number, daily resident rate, longevity, reproductive rate (R, the number of new adults produced per overwintered adults), and survival rate of new adults to the reproductive seasons (Sw). These estimates were compared with those of the Asiu, Kutsuki (A and F), and Kyoto populations, which were previously studied with similar methods and have similar intensities. Asiu and Kutsuki F populations remained at a rather low density with a low R, while Kutsuki A and Kyoto populations reached a high density where food depletion occurred with a high R value. The Yuwaku population often reached a food‐depleting level as in the Kutsuki A and Kyoto populations. It also shared the short life span of overwintered adults (13.5 days) of other high‐density populations; however, it showed much shorter longevity of new adults (36.6 days), much lower R (1.0–2.5), and higher Sw (43%–53%). In some traits the Yuwaku population was similar to the Asiu population: low R, high Sw, and low population variability (SD of log densities; 0.103 and 0.115 for overwintered and new adults, respectively, which were lowest among the populations).
Long‐term responses in arctic ungulate dynamics to changes in climatic and trophic processes
Authors: Forchhammer M. C. , Post E. , Stenseth N. C. , Boertmann D. M.
Published: March 2003

Following predictions from climatic general circulation models, the effects of perturbations in global climate are expected to be most pronounced in the Northern Hemisphere. Elaborating on a recently developed plant–herbivore–climate model, we explore statistically how different winter climate regimes and density‐dependent processes during the past century have affected population dynamics of two arctic ungulate species. Our analyses were performed on the dynamics of six muskox and six caribou populations. In muskoxen, variation in winter climate, mediated through the North Atlantic Oscillation (NAO), explained up to 24% of the variation in interannual abundance, whereas in caribou up to 16% was explained by the NAO. Muskoxen responded negatively following warm and snowy winters, whereas caribou responded negatively to dry winters. Direct and delayed density dependence was recorded in most populations and explained up to 32% and 90% of variations in abundance of muskoxen and caribou, respectively.
The role of antipredator behavior in an experimental community of jumping spiders with intraguild predation
Authors: Okuyama T.
Published: March 2003

The role of direct and indirect interactions in intraguild predation (IGP) was investigated in a laboratory study. The study system contained two spider species, Phidippus audax and Phidippus octopunctatus, and the fruit fly, Drosophila melanogaster. P. audax and P. octopunctatus eat D. melanogaster. P. audax (top predators) also eat P. octopunctatus (intermediate predators). Thus, P. audax and P. octopunctatus compete for the shared resource and also interact as predator and prey. Experiments consisted of two treatments: risk‐IGP and full‐IGP. In the risk‐IGP treatments, I examined the effects of trait‐mediated indirect effects generated by antipredator behavior of P. octopunctatus on the survival of fruit flies. P. audax chelicerae were waxed so that P. audax could not attack a prey. The result indicated a significant positive indirect effect of P. audax on the survival of D. melanogaster due to the antipredator behavior of P. octopunctatus (a trait‐mediated indirect effect). In the full‐IGP treatments, P. audax chelicerae were not restricted, so that it could attack prey; this resulted in decreased survival of D. melanogaster. Because of predation of P. audax on P. octopunctatus, even stronger positive interactions occurred between P. audax and D. melanogaster in full‐IGP than in risk‐IGP.
Resilience Among Urban African American Male Adolescents: A Study of the Protective Effects of Sociopolitical Control on Their Mental Health
Authors: Zimmerman Marc A. , Ramírez-Valles Jesus , Maton Kenneth I.
Published: March 2003

Resilience refers to the notion that some people succeed in the face of adversity. In a risk‐protective model of resilience, a protective factor interacts with a risk factor to mitigate the occurrence of a negative outcome. This study tested longitudinally the protective effects of sociopolitical control on the link between helplessness and mental health. The study included 172 urban, male, African American adolescents, who were interviewed twice, 6 months apart. Sociopolitical control was defined as the beliefs about one's capabilities and efficacy in social and political systems. Two mental health outcomes were examined—psychological symptoms and self‐esteem. Regression analyses to predict psychological symptoms and self‐esteem over time were conducted. High levels of sociopolitical control were found to limit the negative consequences of helplessness on mental health. The results suggest that sociopolitical control may help to protect youths from the negative consequences of feelings of helplessness. Implications for prevention strategies are discussed.