bluuebunny/crossref_metadata_2025 huggingface dataset:
A morphospace‐based test for competitive exclusion among flying vertebrates: did birds, bats and pterosaurs get in each other's space?
Authors: MCGOWAN A. J. , DYKE G. J.
Published: January 2007

Three vertebrate groups – birds, bats and pterosaurs – have evolved flapping flight over the past 200 million years. This innovation allowed each clade access to new ecological opportunities, but did the diversification of one of these groups inhibit the evolutionary radiation of any of the others? A related question is whether having the wing attached to the hindlimbs in bats and pterosaurs constrained their morphological diversity relative to birds. Fore‐ and hindlimb measurements from 894 specimens were used to construct a morphospace to assess morphological overlap and range, a possible indicator of competition, among the three clades. Neither birds nor bats entered pterosaur morphospace across the Cretaceous–Paleogene (Tertiary) extinction. Bats plot in a separate area from birds, and have a significantly smaller morphological range than either birds or pterosaurs. On the basis of these results, competitive exclusion among the three groups is not supported.
Sounds different: inbreeding depression in sexually selected traits in the cricket Teleogryllus commodus
Authors: DRAYTON J. M. , HUNT J. , BROOKS R. , JENNIONS M. D.
Published: January 2007

If male sexual signalling is honest because it captures genetic variation in condition then traits that are important mate choice cues should be disproportionately affected by inbreeding relative to other traits. To test this, we investigated the effect of brother–sister mating on advertisement calling by male field crickets Teleogryllus commodus. We quantified the effect of one generation of inbreeding on nightly calling effort and five finer‐scale aspects of call structure that have been shown to influence attractiveness. We also quantified inbreeding depression on six life history traits and one morphological trait. Inbreeding significantly reduced hatching success, nymph survival and adult lifespan but had no detectable effect on hatching rate, developmental rate or adult body mass. The effect of inbreeding on sexually selected traits was equivocal. There was no decline in calling effort (seconds of sound production/night) by inbred males, but there were highly significant changes in three of five finer‐scale call parameters. Sexually selected traits clearly vary in their susceptibility to inbreeding depression.
Geographic structure in a widespread plant–mycorrhizal interaction: pines and false truffles
Authors: HOEKSEMA J. D. , THOMPSON J. N.
Published: January 2007

Mutualistic interactions are likely to exhibit a strong geographic mosaic in their coevolutionary dynamics, but the structure of geographic variation in these interactions is much more poorly characterized than in host–parasite interactions. We used a cross‐inoculation experiment to characterize the scales and patterns at which geographic structure has evolved in an interaction between three pine species and one ectomycorrhizal fungus species along the west coast of North America. We found substantial and contrasting patterns of geographic interaction structure for the plants and fungi. The fungi exhibited a clinal pattern of local adaptation to their host plants across the geographic range of three coastal pines. In contrast, plant growth parameters were unaffected by fungal variation, but varied among plant populations and species. Both plant and fungal performance measures varied strongly with latitude. This set of results indicates that in such widespread species interactions, interacting species may evolve asymmetrically in a geographic mosaic because of differing evolutionary responses to clinally varying biotic and abiotic factors.
Morphological evidence of correlational selection and ecological segregation between dextral and sinistral forms in a polymorphic flatfish, Platichthys stellatus
Authors: BERGSTROM C. A.
Published: January 2007

Phenotypic polymorphisms in natural systems are often maintained by ecological selection, but only if niche segregation between morphs exists. Polymorphism for eyed‐side direction is rare among the ∼700 species of flatfish (Pleuronectiformes), and the evolutionary mechanisms that maintain it are unknown. Platichthys stellatus (starry flounder) is a polymorphic pleuronectid flatfish exhibiting large, clinal variation in proportion of left‐eyed (sinistral) morphs, from 50% in California to 100% in Japan. Here I examined multiple traits related to swimming and foraging performance between sinistral and dextral morphs of P. stellatus from 12 sites to investigate if the two morphs differ in ways that may affect function and ecology. Direction of body asymmetry was correlated with several other characters: on an average, dextral morphs had longer, wider caudal peduncles, shorter snouts and fewer gill rakers than sinistral morphs. Although the differences were small in magnitude, they were consistent in direction across samples, implying that dextral and sinistral starry flounder may be targeting different prey types. Morphological differences between morphs were greatest in samples where the chances of competitive interactions between them were the greatest. These results suggest that the two morphs are not ecologically identical, may represent a rare example of divergent selection maintaining polymorphism of asymmetric forms, and that correlational selection between body asymmetry and other characters may be driven by competitive interactions between sinistral and dextral flatfish. This study is one of very few that demonstrates the ecological significance of direction in a species with polymorphic asymmetric forms.
An unexpected influence of widely used significance thresholds on the distribution of reported P‐values
Authors: RIDLEY J. , KOLM N. , FRECKELTON R. P. , GAGE M. J. G.
Published: January 2007

We consider the problematic relationship between publication success and statistical significance in the light of analyses in which we examine the distribution of published probability (P) values across the statistical ‘significance’ range, below the 5% probability threshold. P‐values are often judged according to whether they lie beneath traditionally accepted thresholds (< 0.05, < 0.01, < 0.001, < 0.0001); we examine how these thresholds influence the distribution of reported absolute P‐values in published scientific papers, the majority in biological sciences. We collected published P‐values from three leading journals, and summarized their distribution using the frequencies falling across and within these four threshold values between 0.05 and 0. These published frequencies were then fitted to three complementary null models which allowed us to predict the expected proportions of P‐values in the top and bottom half of each inter‐threshold interval (i.e. those lying below, as opposed to above, each P‐value threshold). Statistical comparison of these predicted proportions, against those actually observed, provides the first empirical evidence for a remarkable excess of probability values being cited on, or just below, each threshold relative to the smoothed theoretical distributions. The pattern is consistent across thresholds and journals, and for whichever theoretical approach used to generate our expected proportions. We discuss this novel finding and its implications for solving the problems of publication bias and selective reporting in evolutionary biology.
Assessing the speed and predictability of local adaptation in invasive California poppies (Eschscholzia californica)
Authors: LEGER E. A. , RICE K. J.
Published: January 2007

Insight into the speed and predictability of local adaptation can be gained by studying organisms, such as invasive species, that have recently expanded their geographical ranges. Common garden studies were designed to address these issues with the California poppy,Eschscholzia californica, collected from a wide range of environments in both its native (California) and invasive (Chile) ranges. We found similar patterns of plant trait variation along similar abiotic gradients in plants collected from both areas. Multivariate analysis demonstrated that coastal plants from both areas tended to be shorter, smaller plants with smaller seeds and flowers that germinate and flower later than plants collected from inland locations. In addition, size and fecundity traits in both native and invasive poppies were correlated with average rainfall totals; the plants that grew the largest and were the most fecund during the first year of growth originated from the driest areas. This parallel variation suggests that these traits are adaptive and that these patterns have evolved in Chile during the 110–150 years since introduction.
Macrophyte refuges, prey behaviour and trophic interactions: consequences for lake water clarity
Authors: Genkai‐Kato Motomi
Published: January 2007

Macrophytes may enhance grazing on phytoplankton by providing a refuge for zooplankton against fish predation. Loss of macrophytes can trigger sudden degradation of water clarity (regime shift) in lakes. However, the presence of piscivores may drive planktivorous fish to take refuge amongst littoral macrophytes. To address the possibility of regime shifts, I here constructed an empirically based model that combined population dynamics of organisms with game theory for optimal habitat selection, taking into consideration the trophic structure, lake size and eutrophication. The model showed that macrophytes generally acted as a refuge for zooplankton, rather than for fish. The model predicted that regime shifts were more likely in small, shallow lakes and that the presence of macrophytes raised the possibility of regime shifts. The present study demonstrated that the fast dynamics of animal behaviour could lead to regime shifts, in connection with slower variables such as nutrient loading.
Living in the branches: population dynamics and ecological processes in dendritic networks
Authors: Campbell Grant Evan H. , Lowe Winsor H. , Fagan William F.
Published: January 2007

Spatial structure regulates and modifies processes at several levels of ecological organization (e.g. individual/genetic, population and community) and is thus a key component of complex systems, where knowledge at a small scale can be insufficient for understanding system behaviour at a larger scale. Recent syntheses outline potential applications of network theory to ecological systems, but do not address the implications of physical structure for network dynamics. There is a specific need to examine how dendritic habitat structure, such as that found in stream, hedgerow and cave networks, influences ecological processes. Although dendritic networks are one type of ecological network, they are distinguished by two fundamental characteristics: (1) both the branches and the nodes serve as habitat, and (2) the specific spatial arrangement and hierarchical organization of these elements interacts with a species’ movement behaviour to alter patterns of population distribution and abundance, and community interactions. Here, we summarize existing theory relating to ecological dynamics in dendritic networks, review empirical studies examining the population‐ and community‐level consequences of these networks, and suggest future research integrating spatial pattern and processes in dendritic systems.
Surfactin and fengycin lipopeptides of Bacillus subtilis as elicitors of induced systemic resistance in plants
Authors: Ongena Marc , Jourdan Emmanuel , Adam Akram , Paquot Michel , Brans Alain , Joris Bernard , Arpigny Jean‐Louis , Thonart Philippe
Published: January 2007

Multiple strains of Bacillus spp. were demonstrated to stimulate plant defence responses. However, very little is known about the nature of molecular determinants secreted by these Gram‐positive bacteria that are responsible for the elicitation of the induced systemic resistance (ISR) phenomenon. This study shows that the lipopeptides surfactins and fengycins may be involved in this elicitation process. In bean, pure fengycins and surfactins provided a significant ISR‐mediated protective effect on bean plants, similar to the one induced by living cells of the producing strain S499. Moreover, experiments conducted on bean and tomato plants showed that overexpression of both surfactin and fengycin biosynthetic genes in the naturally poor producer Bacillus subtilis strain 168 was associated with a significant increase in the potential of the derivatives to induce resistance. In tomato cells, key enzymes of the lipoxygenase pathway appeared to be activated in resistant plants following induction by lipopeptide overproducers. To our knowledge, such lipopeptides constitute a novel class of compounds from non‐pathogenic bacteria that can be perceived by plant cells as signals to initiate defence mechanisms.
Molecular characterization of T4‐type bacteriophages in a rice field
Authors: Jia Zhongjun , Ishihara Rie , Nakajima Yasunori , Asakawa Susumu , Kimura Makoto
Published: January 2007

Bacteriophages, the viruses that infect bacteria, are the most abundant biological entities in the biosphere and play a key role in global biogeochemical cycling. All T4‐type bacteriophage isolates tested so far have a conserved genetic module that encodes the virion components including gene 23 (g23), the major capsid protein. Molecular analysis of the g23 sequence revealed a remarkable level of diversity of T4‐type bacteriophages isolated from rice straw and surface soil in a Japanese rice field. It was found that g23 sequences obtained from the rice field were quite distinctive from those obtained in marine environments. Phylogenetic analysis showed that most of these g23 sequences belonged to two novel subgroups of T4‐type bacteriophages, although some of them were related to well‐studied subgroups of T4‐type bacteriophages, such as marine cyanophage isolates of exoT‐evens.
Soil fungal communities in a Castanea sativa (chestnut) forest producing large quantities of Boletus edulis sensu lato (porcini): where is the mycelium of porcini?
Authors: Peintner Ursula , Iotti Mirco , Klotz Petra , Bonuso Enrico , Zambonelli Alessandra
Published: January 2007

A study was conducted in a Castanea sativa forest that produces large quantities of the edible mushroom porcini (Boletus edulis sensu lato). The primary aim was to study porcini mycelia in the soil, and to determine if there were any possible ecological and functional interactions with other dominant soil fungi. Three different approaches were used: collection and morphological identification of fruiting bodies, morphological and molecular identification of ectomycorrhizae by rDNA‐ITS sequence analyses and molecular identification of the soil mycelia by ITS clone libraries. Soil samples were taken directly under basidiomes of Boletus edulis, Boletus aestivalis, Boletus aereus and Boletus pinophilus. Thirty‐nine ectomycorrhizal fungi were identified on root tips whereas 40 fungal species were found in the soil using the cloning technique. The overlap between above‐ and below‐ground fungal communities was very low. Boletus mycelia, compared with other soil fungi, were rare and with scattered distribution, whereas their fruiting bodies dominated the above‐ground fungal community. Only B. aestivalis ectomycorrhizae were relatively abundant and detected as mycelia in the soil. No specific fungus–fungus association was found. Factors triggering formation of mycorrhizae and fructification of porcini appear to be too complex to be simply explained on the basis of the amount of fungal mycelia in the soil.
Host specificity and phylogeography of the prochlorophyte Prochloron sp., an obligate symbiont in didemnid ascidians
Authors: Münchhoff Julia , Hirose Euichi , Maruyama Tadashi , Sunairi Michio , Burns Brendan P. , Neilan Brett A.
Published: January 2007

Prochloron is an oxygenic photosynthetic bacterium that lives in obligate symbiosis with didemnid ascidians, such as Diplosoma spp., Lissoclinum spp. and Trididemnum spp. This study investigated the genetic diversity of the genus Prochloron by constructing a phylogenetic tree based on the 16S rRNA gene sequences of 27 isolates from 11 species of didemnid ascidians collected from Japan, Australia and the USA. The 27 isolates formed three phylogenetic groups: 22 of the samples were identified to be closely related members of Prochloron. Two samples, isolated from Trididemnum nubilum and Trididemnum clinides, were found to belong to the species Synechocystis trididemni, the closest relative of Prochloron. Three isolates formed a separate group from both Prochloron sp. and S. trididemni, potentially indicating a new symbiotic phylotype. Genomic polymorphism analysis, employing cyanobacterium‐specific highly iterative palindrome 1 repeats, could not delineate the isolates further. For the Prochloron sp. isolates, the phylogenetic outcome was independent of host species and geographic origin of the sample indicating a low level of host specificity, low genetic variation within the taxon and possibly a lack of a host–symbiont relationship during reproductive dispersal. This study contributes significantly to the understanding of Prochloron diversity and phylogeny, and implications for the evolutionary relationship of prochlorophytes, cyanobacteria and chloroplasts are also discussed.
Accurate staging, selective preoperative therapy and optimal surgery improves outcome in rectal cancer: a review of the recent evidence
Authors: Daniels I. R. , Fisher S. E. , Heald R. J. , Moran B. J.
Published: January 2007

Objective  The current optimal management of locally advanced rectal cancer has evolved from surgical excision followed by postoperative therapy in patients with involved margins, to an increasing use of a preoperative strategy to ‘down‐stage and/or down‐size’ the tumour. This treatment strategy is based on the relationship of the tumour to the mesorectal fascia, the optimal surgical circumferential resection margin that can be achieved by total mesorectal excision. We have reviewed the recent evidence for this strategy.

Method  An electronic literature search using PubMed identified articles on the subject of rectal cancer between January 2000 and December 2005. The search was limited to English language publications with secondary references obtained from key articles. Articles published in high impact factor journals formed the basis of the review, together with articles related to national programmes on the management of rectal cancer. This does lead to a selection bias, particularly as the articles identified had a European bias.

Conclusion  The UK NHS Cancer Plan has outlined the basis for the multidisciplinary team (MDT) management of rectal cancer. Advances in preoperative assessment through accurate staging and the recognition of the importance of the relationship of the tumour to the mesorectal fascia has allowed the selection of patients for a preoperative strategy to down‐size/down‐stage the tumour if this fascial layer is involved or threatened. Improvements in the quality of surgical resection through the acceptance of the principle of total mesorectal excision have ensured that optimal surgery remains the cornerstone to successful treatment. Further refinements of the MDT process strive to improve outcome. Accurate radiological staging, optimal surgery and detailed histopathological assessment together with consideration of a preoperative neoadjuvant strategy should now form the basis for current treatment and future research in rectal cancer.
Cost analysis of transanal endoscopic microsurgery for rectal tumours
Authors: Maslekar S. , Pillinger S. H. , Sharma A. , Taylor A. , Monson J. R. T.
Published: January 2007

Objective  Transanal endoscopic microsurgery (TEM) is considered to be a safe and effective treatment for selected rectal neoplasms. We demonstrate that in addition to the recognized clinical benefits of the less invasive TEM approach, there are substantial economic benefits.

Method  We reviewed our prospective database of patients undergoing TEM excision of a rectal lesion between July 1997 and December 2003. A cost analysis was undertaken, including procedural and related costs of TEM and compared with the relevant open procedures.

Results  124 patients (80 men, 44 women) with a median age of 71.5 years underwent TEM excision of rectal lesions (52 cancers and 72 adenomas). The morbidity rate was 8% and mortality was zero. A controlled case series of 52 patients undergoing open resection for early rectal cancers with similar characteristics as above was compared in terms of clinical outcome. The morbidity rate in these patients was 29.5%. The cost analysis comparison was undertaken using National Health Service mean reference costs for major large intestinal surgery, Intensive care unit/high dependency unit and hospital accommodation for each procedure. The average cost of open resection was £4135, vs£567 for TEM excision. Our total saving over the series was £525 576. Although the initial capital cost of the TEM equipment is high at approximately £40 000 given the massive cost savings, these initial equipment costs are recovered within a rapid time frame.

Conclusion  This study has shown that TEM is a safe and extremely cost‐effective approach for excision of selected rectal tumours including rectal adenomas and early well differentiated rectal cancers (pTis & pT1).
Intermediate sized adenomas may represent an increased cancer risk
Authors: Pearson T. E. , Lewis G. , Bugg W. , Bright P. , Lillie J. , Marks C.
Published: January 2007

Objective:  The purpose of colonoscopic polypectomy is cancer prevention. Multiple or large adenomas require intensive follow up but solitary or smaller lesions are considered safer and less frequent examinations are necessary. The aim of this study was to test if these principles are supported in practice.

Method:  Individuals with polyps but no family history of CRC, where pathology and endoscopy reports could be cross‐referenced to confirm size, number and histological classification were included. Cases of colorectal cancer were identified from records of repeat examinations. Follow up interval and number of subsequent examinations was determined. A control population of individuals with a normal initial colonoscopy were also studied.

Results:  In total 0.05% of individuals with a normal initial colonoscopy developed CRC. The cancer incidence following numerous or large polyps was not significantly higher than the controls although on average more examinations were performed (see table). Individuals with a single small adenoma did not appear to have increased risk of cancer with fewer colonoscopies, but there were significantly higher numbers of cancers where intermediate sized polyps had been identified.

First Exam result
Number
Follow up (months)
Number of exams
Metachronous cancers

Normal
4935
88.7 (1–201)
1.2
24 (0.05%)

Single (<5 mm)
74
64.3 (7–148)
1.3
1 (1.4%)
χ2 = 1.1 P = 0.29

Between 5 mm and 10 mm
73
73.4 (6–165)
1.5
3 (4.1%)
χ2 = 17.61 P < 0.0001

More than 3
27
68.1 (6–152)
2.5
0 (0%)
χ2 = 0.13 P = 0.72

Larger than 10 mm
114
73.7 (3–170)
2.9
1 (0.9%)
χ2 = 0.35 P = 0.56

Conclusion:  Risk of cancer is reduced in large or numerous polyps by frequent examinations. Intermediate sized polyps appear to need more intensive follow‐up protocols than small single adenomas for effective cancer prevention.
Magnetic resonance imaging predicts circumferential resection margin status in patients receiving preoperative chemoradiotherapy for rectal cancer
Authors: Hancock L. , Forde C. , Bradbury J. , Mortensen N. , Gleeson F.
Published: January 2007

Objective:  Accurate tumour re‐assessment after down‐sizing preoperative chemoradiotherapy (CRT) for locally advanced middle and lower rectal cancer provides valuable prognostic information prior to surgical resection. We assessed the accuracy of post‐CRT magnetic resonance imaging (MRI) in predicting circumferential resection margin status. The accuracy of MRI in staging chemoradiation down‐sized rectal tumours was also assessed.

Method:  Patients from a single tertiary referral centre who received preoperative CRT for biopsy‐proven rectal cancer between January 2003 and February 2005 were identified from a database. All patients received long‐course CRT (50Gy over 5 weeks and five‐fluorouracil/leucovorin) prior to surgery. A comprehensive MRI reporting proforma was completed for each patient and results were compared directly with histological specimens.

Results:  A total of 50 patients were eligible for the study. The overall accuracy for predicting circumferential resection margin status was 76% (38/50, P = 0.006, sensitivity = 96.9%, specificity = 73.8%, negative predictive value = 96.9%). For T staging MRI was accurate in 52% (26/50) and for nodal staging MRI was correct in 60% (30/50). Venous invasion was predicted in 66% (33/50, P = 0.04). A radiological rectal cancer regression grade was derived and this correlated with histological rectal cancer regression grade in 65% (32/49).

Conclusion:  This study demonstrates that post‐CRT MRI is accurate in predicting the circumferential resection margin status which provides useful prognostic information prior to surgery.
Acute diverticulitis – clinical presentation and differential diagnostics
Authors: Laurell H. , Hansson L.‐E. , Gunnarsson U.
Published: January 2007

Objective  To describe the clinical presentation of acute diverticulitis in an emergency department and to characterize the natural history of diverticulitis in the short perspective. Comparisons are made with an important differential diagnosis, nonspecific abdominal pain (NSAP).

Method  Patients admitted to our hospital with abdominal pain of up to 7 days’ duration were registered prospectively using a detailed schedule for history, symptoms and signs, from 1 February 1997 to 1 June 2000. Of 3349 patients initially included, 3073 (92%) were eligible for follow up after 1–3 years.

Results  Acute diverticulitis was the final diagnosis in 145 patients and NSAP in 1142 patients. The incidence of hospitalized patients with diverticulitis was 47 per year and 100 000 population, with a mean hospital stay of 3.3 days. Patients with diverticulitis, more frequently than NSAP, had a longer history and laboratory signs of inflammatory activity. Isolated left abdominal tenderness was more common in diverticulitis, whereas isolated right abdominal tenderness was more common in NSAP. Duration of symptoms on arrival was independent of age and was not correlated to C‐reactive protein, leucocytes or body temperature. Sensitivity of diverticulitis as primary diagnosis was 64% and specificity 97%. Corresponding figures for NSAP were 43% and 90% respectively. Age and gender did not influence diagnostic accuracy or risk of surgery.

Conclusion  Diverticulitis differs significantly from NSAP in clinical presentation and laboratory parameters. Sensitivity of primary diagnosis for diverticulitis and NSAP was low.
Long‐term results of perianal silicone injection for faecal incontinence
Authors: Maeda Y. , Vaizey C. J. , Kamm M. A.
Published: January 2007

Objective  Perianal injection of bulking agents is a simple method for treating passive faecal incontinence. To date only short‐term results of treatment are available. This study is the first to determine the efficacy of silicone biomaterial (PTQTM; Uroplasty BV, Geleen, The Netherlands) injection in the long term.

Method  Six patients, median age 53 years at the time of injection with PTQ, were followed up at 61 months. A validated faecal incontinence score, treatment‐specific questionnaire and SF‐36 health survey questionnaire were completed.

Results  At 61‐month follow up one patient had undergone a colostomy for faecal incontinence. In the remaining five patients the incontinence score was little changed: 11 (8–20) vs 13 (9–19) [pre v at 61 months, median (range)]. However, there was a substantial improvement in physical and social function on the SF‐36 scores. Satisfaction scores were high at a median 7 of 10 (range: 0–8). Subjectively, three patients were improved; one of these had undergone a further set of injections and one improved after a course of biofeedback. After the follow‐up period one of the five patients had a colostomy for recto‐vaginal fistula.

Conclusion  The results of perianal injection of PTQ for passive faecal incontinence are variable in the long term. More extensive evaluation in the short term, and possibly repeated treatment, may be required.
A comparison of quality of life and postoperative results from combined PPH and conventional haemorrhoidectomy in different cases of haemorrhoidal disease
Authors: Martinsons A. , Narbuts Z. , Brunenieks I. , Pavars M. , Lebedkovs S. , Gardovskis J.
Published: January 2007

Objective  To compare the early postoperative results and late patient‐related postoperative results by a Short‐Form 36 quality of life survey after conventional haemorrhoidectomy and PPH procedure with additional surgical intervention in noncomplicated, complicated and delayed cases of the disease.

Method  The comparison was made between comparable patient groups after conventional haemorrhoidectomy (n = 168) and after PPH with additional surgical intervention (n = 142). The early and late postoperative results and quality of life analysis according to SF‐36® questionnaire were compared.

Results  The length of procedure was significantly shorter after the PPH procedure (37.4 vs 49.4 min). The amount of postoperative nonopiate analgesics was similar, but consumption of opiates was more in the conventional group. The rate of early postoperative complications was similar. In the PPH group significant improvement in all quality of life parameters was ascertained 6 months after operation, but 6 weeks after surgery several parameters in this group were lower. In the conventional group improvement was ascertained only for several parameters. The significant improvement of quality of life after PPH operations was ascertained especially at a mean period of 6 weeks.

Conclusion  The PPH procedure performed in complex cases of the disease and combined with other surgical intervention because of the anorectal comorbidity assures better early postoperative results and better postoperative quality of life in a 6‐month follow up in comparison with conventional haemorrhoidectomy. The continuation of quality of life studies with a longer follow up is required concerning Longo operation.
Long‐term outcome in 445 patients after diagnosis of diverticular disease
Authors: Moreno A. M. , Wille‐Jørgensen P.
Published: January 2007

Objective  To describe the long‐term outcome after primary diagnosis of diverticular disease (DD) with respect to demographics, lifestyle, severity of disease and primary treatment.

Method  Retrospective cohort study of all 445 consecutive patients admitted to the department during 1989–1995 with the diagnosis DD with prospective follow up. Follow up was performed on all patients during May 2002 by searching the Danish Patient Register and National Register. Logistic regression analyses were applied for defining risk factors for readmission or death. For defined risk factors Kaplan–Meier survival statistics was performed.

Results  The male/female ratio was 30/70. Median age was 75 years (men being younger than women, P < 0.01). About 73% received conservative treatment primarily. At follow up 35.3% had suffered clinical recurrence of DD, of these 15.9% were subsequently operated. However, 3.6% of the patients died of causes related to diverticulitis. Possible high‐risk groups for recurrence were males and their age above 70 years.

Conclusion  Age and sex are possible predictors for recurrence of DD. Elective surgery seems not to be justified after just one attack of DD.
l‐Alanin‐l‐glutamine supplementation improves the outcome after colorectal surgery for cancer
Authors: Oguz M. , Kerem M. , Bedirli A. , Mentes B. B. , Sakrak O. , Salman B. , Bostanci H.
Published: January 2007

Objective  To investigate the effect of l‐alanine‐l‐glutamine (Gln) on postoperative complication rate and duration of hospitalization in patients operated for colorectal cancer.

Method  A total of 109 patients operated with the diagnosis of colorectal cancer and given enteral nutrition between January 2001 and January 2005 were prospectively analysed. The patients were randomized and analysed in two groups; Gln group (n = 57): patients were given parenteral Gln (1 g/kg/day, Dipeptiven, Fresenuis Kabi, Germany) together with enteral nutrition (Ensure; Abbott, Zwolle, The Netherlands) and the control group (n = 52) only received enteral nutrition (Ensure; Abbott), which was a standard isonitrogenous and isocaloric formula. The supplemental enteral nutrition was provided for at least 5 days pre‐ and postoperatively according to the nutritional status of the patients. Age, gender, subjective global assessment (SGA), body mass index (BMI), serum albumin, protein, associated disorders, localization of pathology, techniques of anastomosis, postoperative complications and length of hospital stay were analysed for each patient.

Results  The duration of nutritional support in the Gln group was 6 ± 2 and 5 ± 1 days pre‐ and postoperatively; while it was 7 ± 1 and 6 ± 1 days for the control group, and there were no significant difference among the groups (P > 0.05). Age, gender, SGA, BMI, levels of serum albumin and protein, localization of pathology and techniques of anastomosis were also similar (P > 0.05). Wound infection (P = 0.038), intraabdominal abcess formation (P = 0.044) and wound dehiscence (P = 0.044) were significantly higher in the control group than in the Gln group. There was no significant difference in terms of anastomotic leakage and other complications between both groups (P > 0.05). Hospital stay was significantly shorter in the Gln group (P < 0.001).

Conclusion  Supplementation of parenteral Gln decreased the postoperative complications and hospital stay and in the patients undergoing the colorectal surgery for cancer.
The proportion of cores with high‐grade prostatic intraepithelial neoplasia on extended‐pattern needle biopsy is significantly associated with prostate cancer on site‐directed repeat biopsy
Authors: Akhavan Ardavan , Keith Jonathan D. , Bastacky Sheldon I. , Cai Chao , Wang Yun , Nelson Joel B.
Published: January 2007

OBJECTIVE

To determine whether the predictive value of isolated high‐grade prostatic intraepithelial neoplasia (HGPIN) for an unsampled prostate cancer on an extended biopsy is lower due to more thorough prostate sampling, and whether the proportion of cores with HGPIN is associated with prostate cancer, as isolated HGPIN on sextant prostate biopsy is associated with a 27–57% risk of prostate cancer on repeat biopsy.

PATIENTS AND METHODS

All extended prostate biopsies taken by one urologist over 6 years were reviewed for patients with isolated HGPIN on initial biopsy. Biopsies were evaluated for histological features and the proportion of cores with HGPIN. The clinical characteristics and pathological findings from subsequent biopsies were determined.

RESULTS

Of 577 men having extended biopsies, 48 had isolated HGPIN, followed by one to four site‐directed repeat biopsies. Although only 10 (21%) had cancer on the first repeat biopsy, overall 15 (31%) had cancer. Those with cancer on repeat biopsy had a significantly higher proportion of cores with HGPIN, i.e. 29% vs 15%, cancer vs no cancer, respectively (P = 0.04).

CONCLUSIONS

Isolated HGPIN on extended biopsy conferred a 31% risk of unsampled prostate cancer. The proportion of cores with HGPIN on initial biopsy was significantly associated with the risk of cancer. The same was not true for age, race, prostate‐specific antigen level, or the findings on digital rectal examination. The significant association between the proportion of cores with HGPIN and the risk of cancer suggests that patients with unifocal HGPIN on extended biopsy be managed expectantly, whereas those with multifocal HGPIN be re‐biopsied.
NTT DoCoMo's Launch of I‐Mode in the Japanese Mobile Phone Market: A Knowledge Creation Perspective*
Authors: Peltokorpi Vesa , Nonaka Ikujiro , Kodama Mitsuru
Published: January 2007

abstract While innovation and knowledge creation processes and context are interlinked in the real world, scholars frequently ignore or separate context from knowing due to an entrenched sense of ontological and analytical dualism. This paper builds on the organizational knowledge creation theory (Nonaka, 1994) to provide a holistic view of contextual innovation and knowledge creation processes. The phenomenon is demonstrated by a longitudinal case description of i‐mode mobile Internet innovation at NTT DoCoMo, a Japanese mobile communications company. This case explains how three key managers created and organized an interlinked system of shared contexts, calledba, that enabled the combination and open flow of diverse knowledge and led to the creation and launch of the i‐mode mobile Internet, which unites novel technologies and services. Managerial implications and limitations are discussed.
The Development of Organizational Social Capital: Attributes of Family Firms*
Authors: Arregle Jean‐Luc , Hitt Michael A. , Sirmon David G. , Very Philippe
Published: January 2007

abstract  We develop and extend social capital theory by exploring the creation of organizational social capital within a highly pervasive, yet often overlooked organizational form: family firms. We argue that family firms are unique in that, although they work as a single entity, at least two forms of social capital coexist: the family's and the firm's. We investigate mechanisms that link a family's social capital to the creation of the family firm's social capital and examine how factors underlying the family's social capital affect this creation. Moreover, we identify contingency dimensions that affect these relationships and the potential risks associated with family social capital. Finally, we suggest these insights are generalizable to several other types of organizations with similar characteristics.
Knowledge Management as the Basis of Sustained High Performance
Authors: Bogner William C. , Bansal Pratima
Published: January 2007

abstract By deconstructing some of the key elements of the resource‐based view and the knowledge‐based view of the firm, we suggest that there are three components to knowledge management systems that influence firm performance: the firm's ability to produce new knowledge, its ability to build on that knowledge, and its effectiveness in capturing a high proportion of the subsequent spin‐offs. Using regression analysis to analyse data from 30,022 patent records from 42 firms, we find that a firm's growth rate is positively associated with its ability to generate rare and valuable knowledge, and to build on that knowledge.
Multivariate Portmanteau Test For Autoregressive Models with Uncorrelated but Nonindependent Errors
Authors: Francq Christian , Raïssi Hamdi
Published: January 2007

Abstract. We study the asymptotic behaviour of the least squares estimator, of the residual autocorrelations and of the Ljung–Box (or Box–Pierce) portmanteau test statistic for multiple autoregressive time series models with nonindependent innovations. Under mild assumptions, it is shown that the asymptotic distribution of the portmanteau tests is that of a weighted sum of independent chi‐squared random variables. When the innovations exhibit conditional heteroscedasticity or other forms of dependence, this asymptotic distribution can be quite different from that of models with independent and identically distributed innovations. Consequently, the usual chi‐squared distribution does not provide an adequate approximation to the distribution of the Box–Pierce goodness‐of‐fit portmanteau test in the presence of nonindependent innovations. Hence we propose a method to adjust the critical values of the portmanteau tests. Monte carlo experiments illustrate the finite sample performance of the modified portmanteau test.
Responsive Regulation and Taxation: Introduction
Authors: BRAITHWAITE VALERIE
Published: January 2007

The implementation of responsive regulation in taxation means influencing the community's commitment to pay tax through respectful treatment, through attending to resistance and reforming faulty processes, through fairly directed and fully explained disapproval of non‐compliant behavior, through preparedness to administer sanctions, and capacity to follow through to escalate regulatory intervention in the face of continuing non‐compliance. Responsive regulation and regulatory formalism are pitted against each other in this issue on responsive regulation and taxation. Normative and explanatory arguments in favor of responsive regulation are explored by data collected in taxation contexts; and institutional obstacles are identified that limit effective implementation.
Constructing Compliance: Game Playing, Tax Law, and the Regulatory State
Authors: PICCIOTTO SOL
Published: January 2007

This article proposes a rethinking of approaches to compliance, extending perspectives that view regulation as an interactive or reflexive process mediated by sociolinguistic practices. These suggest that the meaning of rules is not fixed ex ante, but may emerge and change through such interactions, which therefore actually help to construct what it means to comply. The analysis supports proposals to base tax law on purposive general principles combined with detailed rules. However, it suggests that this should be the approach adopted for the tax code as a whole, instead of focusing mainly on the merits of a general anti‐avoidance principle, as some of the recent debates have done. The article explores the question of interpretation of rules and the problem of avoidance and game playing. It reexamines the issue of the indeterminacy of rules and relocates it within the context of professional and regulatory practices, suggesting that it is these interactions that construct the meaning of rules and hence of compliance. The analysis is applied to income taxation, to sketch out how the international tax system has been constructed through the interaction of contending views of fairness in the allocation of tax jurisdiction, while in the process becoming refined into a formalist and technicist process of game playing. It argues that the central factor in this process has been the inherent contestability of the core concepts of international taxation, the rules on corporate residence and source of income. The article concludes by considering some of the current proposals for improving tax compliance, in particular by reducing complexity, improving clarity, and the use of broad principles.
The Multiplicity of Taxpayer Identities and Their Implications for Tax Ethics
Authors: WENZEL MICHAEL
Published: January 2007

It is argued that many social factors (ethics, norms, legitimacy) affecting tax compliance derive their meaning and potency from taxpayers’ identities—the way they position themselves socially, relative to other taxpayers and the tax authority. Based on survey data from 965 Australians, the present study investigates taxpayers’ identities at three different levels of inclusiveness (personal, subgroup, and national identity) and their implications for tax‐ethical attitudes. An inclusive identity in terms of one's nation was related to attitudes most conducive to tax compliance. It is concluded that the concept of identity is key to responsive regulation.
Tax Compliance as the Result of a Psychological Tax Contract: The Role of Incentives and Responsive Regulation
Authors: FELD LARS P. , FREY BRUNO S.
Published: January 2007

A psychological tax contract goes beyond the traditional deterrence model and explains tax morale as a complicated interaction between taxpayers and the government. As a contractual relationship implies duties and rights for each contract party, tax compliance is increased by sticking to the fiscal exchange paradigm between citizens and the state. Citizens are willing to honestly declare income even if they do not receive a full public good equivalent to tax payments as long as the political process is perceived to be fair and legitimate. Moreover, friendly treatment of taxpayers by the tax office in auditing processes increases tax compliance.
Taxation Threat, Motivational Postures, and Responsive Regulation
Authors: BRAITHWAITE VALERIE , MURPHY KRISTINA , REINHART MONIKA
Published: January 2007

The central proposition of motivational posturing theory is that regulatees place social distance between themselves and authority, communicating the nature of that distance through a narrative that protects the self from negative appraisal by the authority. One of the key components of posturing is the coping sensibility that individuals adopt to manage the threat of authority. At a baseline level, authorities make demands on citizens and as such threaten individual freedom. At the highest level, authorities threaten through punishment for non‐compliance. Data collected from 3,253 randomly selected Australian taxpayers and a special group of 2,292 taxpayers in conflict with the tax authority are used to show that in both groups, three coping sensibilities contribute to posturing (“thinking morally,”“feeling oppressed,” and “taking control”), and that all three sensibilities are significantly heightened in the group experiencing conflict with the authority. The article argues that the most effective regulatory outcome is achieved when the regulatory process can dampen the “taking control” and “feeling oppressed” sensibilities, and strengthen the “thinking morally” sensibility. Responsive regulation is an approach that encourages tax authorities to read motivational postures, understand the sensibilities that shape them, and tailor a regulatory intervention accordingly.
A DIFFUSION MODEL FOR ELECTRICITY PRICES
Authors: Barlow M. T.
Published: January 2007

Starting from a simple supply/demand model for electricity, we obtain a diffusion (i.e., jumpless) model for spot prices which can exhibit price spikes. We estimate the parameters in the model using historical data from the Alberta and California markets. and compare this model with some others used for spot prices.
PARTIAL HEDGING IN A STOCHASTIC VOLATILITY ENVIRONMENT
Authors: Jonsson Mattias , Sircar K. Ronnie
Published: January 2007

We consider the problem of partial hedging of derivative risk in a stochastic volatility environment. It is related to state‐dependent utility maximization problems in classical economics. We derive the dual problem from the Legendre transform of the associated Bellman equation and interpret the optimal strategy as the perfect hedging strategy for a modified claim. Under the assumption that volatility is fast mean‐reverting and using a singular perturbation analysis, we derive approximate value functions and strategies that are easy to implement and study. The analysis identifies the usual mean historical volatility and the harmonically averaged long‐run volatility as important statistics for such optimization problems without further specification of a stochastic volatility model. The approximation can be improved by specifying a model and can be calibrated for the leverage effect from the implied volatility skew. We study the effectiveness of these strategies using simulated stock paths.
MONOTONICITY AND CONVEXITY OF OPTION PRICES REVISITED
Authors: Kijima Masaaki
Published: January 2007

The Black‐Scholes option price is increasing and convex with respect to the initial stock price. increasing with respect to volatility and instantaneous interest rate, and decreasing and convex with respect to the strike price. These results have been extended in various directions. In particular, when the underlying stock price follows a one‐dimensional diffusion and interest rates are deterministic, it is well known that a European contingent claim's price written on the stock with a convex (concave. respectively) payoff function is also convex (concave) with respect to the initial stock price. This paper discusses extensions of such results under more general settings by simple arguments.