bluuebunny/crossref_metadata_2025 huggingface dataset:
Absence of the Contralateral Internal Carotid Artery: A Challenge for Management of Ipsilateral Glomus Jugulare and Glomus Vagale Tumors
Authors: Piazza Paolo , Di Lella Filippo , Menozzi Roberto , Bacciu Andrea , Sanna Mario
Published: June 2007

Objective: Extensive involvement of the internal carotid artery (ICA) by jugular and vagal paragangliomas represents a challenging problem for skull‐base surgeons: radical tumor resection and preservation of the vessel often cannot be achieved in these cases. The aim of this article was to report the management of a complex case of right ipsilateral jugular and vagal paragangliomas in a patient with absence of the contralateral ICA due to a previous removal of a left carotid body tumor. Surgical removal of the lesions was performed after stenting of the cervical and intratemporal segment of the ICA.

Methods: The charts and all the examinations of the patient were retrospectively reviewed. The patient, a 40‐year‐old man, was treated at the Gruppo Otologico, a private quaternary referral center for neurotology and skull‐base surgery.

Results: The tumors were completely resected during surgery and manipulation of the ICA was greatly facilitated by the stent. No complication occurred during or immediately after surgery; after a follow‐up period of 24 months there was no sign of recurrence and imaging studies demonstrated patency of the stented vessel.

Conclusion: This report suggests that placement of endovascular stents in the cervical and temporal segments of the ICA has the potential of changing the whole therapeutic management in cases of temporal and vagal paragangliomas that surround and invade the vessel, especially in those cases in which permanent balloon occlusion of the ICA is not feasible.
532 nm Pulsed Potassium‐Titanyl‐Phosphate Laser Treatment of Laryngeal Papillomatosis under General Anesthesia
Authors: Burns James A. , Zeitels Steven M. , Akst Lee M. , Broadhurst Matthew S. , Hillman Robert E. , Anderson Rox
Published: June 2007

Objectives: Angiolytic lasers have been shown to be an effective treatment strategy for laryngeal papillomatosis. These lasers precisely target hemoglobin within the microcirculation of papillary lesions. We have previously demonstrated the advantages of the fiber‐based pulsed 532‐nm potassium‐titanyl‐phosphate (KTP) laser in an office setting (with local anesthesia). This investigation provides the first report of the pulsed‐KTP laser during microlaryngoscopy under general anesthesia.

Study Design: A prospective pilot study was performed in 55 adult patients with laryngeal papillomatosis to determine disease response.

Methods: During suspension microlaryngoscopy, a solid‐state 532 nm pulsed‐KTP laser was used (15 ms pulse width, 5.25–7.5 J/pulse maximum output, 2 Hz repetition rate, 0.4 mm fiber, approximately 20–80 J/cm2 fluence) to treat laryngeal papillomatosis. All patients underwent postoperative videolaryngoscopy to assess disease regression based on a previously used rating scale.

Results: Thirty‐seven patients underwent 55 procedures during the 18‐month study period. Near‐term follow‐up with an early postoperative evaluation was available in 23 patients (35 procedures). Fourteen patients (20 procedures) were geographically distant and only returned after developing symptoms with significant disease recurrence. Of the 35 procedures in which near‐term follow‐up was available, 90% or greater disease regression was achieved in 28 of 35 (80%), 75% to 89% disease regression was achieved in 4 of 35 (11%), and 50% to 74% disease regression in 3 of 35 (9%). Anterior‐commissure disease was present in 51 of 55 (93%) cases, and no new webbing/synechia occurred. All patients reported that their vocal function improved after treatment.

Conclusions: The 532 nm pulsed‐KTP laser was effective for treating recurrent respiratory papillomatosis, which was similar to our experience as an office‐based procedure.
Cochlear Implant Electrode Insertion: The Round Window Revisited
Authors: Roland Peter S. , Wright Charles G. , Isaacson Brandon
Published: June 2007

Objective: To examine aspects of round window (RW) anatomy that are relevant to its use as a portal for atraumatic insertion of cochlear implant electrodes.

Study Design: Anatomic study using human cadaveric temporal bones.

Methods: A series of 30 temporal bones was dissected to permit microscopic study of the RW region.

Results: The bony overhangs of the RW niche limit visibility of the RW membrane during surgery. Measurements of RW membrane area visible through a facial recess opening before and after drilling the overhangs in 15 temporal bones showed that RW membrane visibility is typically increased by a factor of 1.5 to 3 times after drilling and by as much as 13 times when the opening of the RW niche is relatively small. Observations from within the scala tympani in 15 cochlear dissections showed substantial variability in size of the RW opening available for electrode insertion. Area measurements of the portion of the RW covered by the vertical segment of the RW membrane ranged from 0.8 to 1.75 mm2 in these specimens. In addition, irregularities in contour of the RW margin may make insertion challenging, which may necessitate drilling the anterior‐inferior margin of the RW. Drilling in this region should be approached with care because of the close proximity of the cochlear aqueduct opening.

Conclusion: RW insertion can be performed in a manner that is potentially less traumatic than the standard cochleostomy insertion. It may therefore be advantageous in cases in which hearing preservation is the goal.
Role of Extra‐Esophageal Reflux in Chronic Otitis Media with Effusion
Authors: Crapko Matthew , Kerschner Joseph E. , Syring Michael , Johnston Nikki
Published: June 2007

Objectives/Hypothesis: Otitis media with effusion (OME) is the most common cause of childhood hearing loss. Despite its prevalence, the enormous health care expenditures resulting from its treatment, and the increasing therapeutic challenges imposed by antimicrobial resistance, very little is known regarding the cellular and molecular immunologic and inflammatory events in this disease process. Extra‐esophageal reflux (EER) has been implicated in the pathogenesis of chronic OME. The objective of this study was to confirm that children with OME have EER into the middle ear as measured by the presence of pepsin in middle ear effusions (MEE) removed during tympanostomy tube (TT) placement.

Study Design: Prospective, translational, cell biological research study.

Methods: MEE were obtained from children undergoing TT placement for OME. The fluid was lysed in a urea buffer and the presence of pepsin quantitatively determined by Western blot analysis using a specific antipepsin antibody. The pH of the samples was recorded before lysis.

Results: Pepsin protein was detected in 18 of 32 (56%) samples analyzed, with 12 of 20 (60%) patients having at least one positive sample for pepsin. Pepsin levels ranged from 80 to 1,000 ng/mL. The pH of the samples ranged from 6.0 to 7.6, with a mean pH of 6.8.

Conclusions: Pepsin was detected in 60% of patients with OME, confirming that EER into the middle ear occurs in these children. The pepsin present would have little or no activity at pH 6.0 to 7.6; however, pepsin is stable below pH 8.0 and thus could be reactivated after a decrease in pH.
Swallowing Function Following Extensive Resection of Oral or Oropharyngeal Cancer With Laryngeal Suspension and Cricopharyngeal Myotomy
Authors: Fujimoto Yasushi , Hasegawa Yasuhisa , Yamada Hiroko , Ando Atsushi , Nakashima Tsutomu
Published: June 2007

Objective: To investigate factors that influence postoperative swallowing function in patients who underwent tongue and oropharynx resection.

Methods: Sixty‐two subjects who had undergone extensive resection of oral or oropharyngeal cancer between 1993 and 2005 participated in this study. All surgical procedures involved excision of the bilateral suprahyoid muscles or of ≥50% of the tongue base. Laryngeal suspension and cricopharyngeal myotomy were performed on all subjects. A multivariate analysis of the effects of extensive tongue and oropharynx resection on swallowing function was performed.

Results: A total of 53 (85.5%) of the 62 subjects achieved independent oral intake and no longer required tube feeding. Six months after surgery, better eating capabilities had been attained by younger patients as compared with older patients; patients with less extensive tongue base resections; patients who had not undergone radiotherapy; and patients reconstructed with free flaps rather than pedicled flaps.

Conclusions: Age was found to be the most important factor in determining whether a patient could achieve independent oral intake after extensive oral or oropharyngeal resection. The main factors in determining the quality of diet attained by the patient were found to be age, the percentage of tongue base resection, and the method of postoperative reconstruction.
Frontal Ostium Restenosis After the Endoscopic Modified Lothrop Procedure
Authors: Tran Khanh N. , Beule Achim G. , Singal Deepti , Wormald Peter‐John
Published: June 2007

Objectives: To evaluate the time course and extent of the restenosis that occurs after an endoscopic modified Lothrop procedure (EMLP) and to identify factors that contribute to this process.

Study Design: Retrospective study of prospectively collected data.

Methods: Seventy‐seven consecutive patients undergoing EMLP between November 1998 and June 2005 with frontal ostium measurements documented intraoperatively and at follow‐up visits for a minimum of 12 months were included. Data on patient demographics, medical history, comorbidities, and computed tomography scans were collected.

Results: Significant restenosis of the frontal sinus neo‐ostia was defined as a loss of more than 60% of the original intraoperative area. The mean follow‐up in our cohort was 29.2 months. Twenty‐two patients were identified with increased stenosis, all of which arose within the first 12 months postsurgery. Nine of these 22 patients required revision EMLP. In all patients, the new frontal ostium narrowed at 1 year by an average of 33% (from 290 to 191 mm2, confidence interval 159–223 mm2). Restenosis and revision surgery are partly predicted by the presence of eosinophilic mucin chronic rhinosinusitis as demonstrated by logistic regression analysis. Linear regression analysis confirmed that the intraoperative frontal ostium size determines the frontal ostium area at 1 year.

Conclusion: This study provides benchmarking values for the time course of the frontal ostium area after EMLP for normal wound healing and increased stenosis. On the basis of our results, patients with a higher risk for developing restenosis and of having revision surgery can be identified preoperatively and during the early postoperative period to facilitate special postoperative care.
A Comparison of Postcochlear Implantation Speech Scores in an Adult Population
Authors: Bodmer Daniel , Shipp David B. , Ostroff Jodi M. , Ng Amy H. C. , Stewart Suzanne , Chen Joseph M. , Nedzelski Julian M.
Published: June 2007

Objectives: The vast majority of cochlear implant recipients realize significant improvement in speech perception. However, there continue to be a small group that does not realize such a benefit. In an effort to identify possible predictors for this, we have compared pre‐ and postimplant audiologic data using Hearing In Noise Test (HINT), City University of New York (CUNY), or Central Institute for the Deaf (CID) scores for 445 consecutive English‐speaking adult patients followed for a minimum of 1 year postimplantation in two distinct groups, poor versus excellent performers.

Study Design: Retrospective.

Methods: Poor performers were those who realized a worsening, no improvement, or an improvement of less than 10%. This group numbered 58 (13%). High performers consisted of a cadre of 194 (44%) patients who scored between 91 and 100% postimplantation. Demographic data relating to onset of deafness, education exposure, etiology, etc., were evaluated.

Results: Of the poor performers, 33 (57%) were pre‐/perilingually deafened. Of these, 79% had not received any auditory/oral training in childhood. On the other hand, a total of 109 implant recipients were individuals who were pre‐/perilingually deafened. Of these, 24 were in the excellent performer category. All were identified early and were recipients of a strong auditory/oral education. Of the high performers, 170 (88%) were deafened late. Other findings such as preoperative electronystagmography with caloric testing, hearing aid use, device type, and high‐resolution computed tomography scan of the temporal bone will be discussed for both groups.

Conclusions: A high preimplant speech score, auditory verbal therapy, and postlingual deafness statistically correlate with higher postimplant speech scores 1 year after cochlear implantation. Device type, caloric response and hearing aid use preimplantation, age at surgery, and sex do not statistically correlate with either poor or excellent speech discrimination scores postcochlear implantation.
Male monkeys remember which group members have given alarm calls
Authors: Wich Serge A , de Vries Han
Published: June 2007

Primates give alarm calls in response to the presence of predators. In some species, such as the Thomas langur (
Presbytis thomasi
), males only emit alarm calls if there is an audience. An unanswered question is whether the audience's behaviour influences how long the male will continue his alarm calling. We tested three hypotheses that might explain the alarm calling duration of male Thomas langurs: the
fatigue
,
group size
and
group member behaviour
hypotheses. Fatigue and group size did not influence male alarm calling duration. We found that males only ceased calling shortly after all individuals in his group had given at least one alarm call. This shows that males keep track of and thus remember which group members have called.
The influence of juvenile and adult environments on life-history trajectories
Authors: Taborsky Barbara
Published: June 2007

There is increasing evidence that the environment experienced early in life can strongly influence adult life histories. It is largely unknown, however, how past and present conditions influence suites of life-history traits regarding major life-history trade-offs. Especially in animals with indeterminate growth, we may expect that environmental conditions of juveniles and adults independently or interactively influence the life-history trade-off between growth and reproduction after maturation. Juvenile growth conditions may initiate a feedback loop determining adult allocation patterns, triggered by size-dependent mortality risk. I tested this possibility in a long-term growth experiment with mouthbrooding cichlids. Females were raised either on a high-food or low-food diet. After maturation half of them were switched to the opposite treatment, while the other half remained unchanged. Adult growth was determined by current resource availability, but key reproductive traits like reproductive rate and offspring size were only influenced by juvenile growth conditions, irrespective of the ration received as adults. Moreover, the allocation of resources to growth versus reproduction and to offspring number versus size were shaped by juvenile rather than adult ecology. These results indicate that early individual history must be considered when analysing causes of life-history variation in natural populations.
Environmental variability and the initiation of dispersal: turbulence strongly increases seed release
Authors: Skarpaas Olav , Auhl Richard , Shea Katriona
Published: June 2007

Dispersal is a critical process in ecology. It is an important biological driver of, for example, invasions, metapopulation dynamics, spatial pattern formation and pathogen movement. Much is known about the effect of environmental variability, including turbulence, on dispersal of diaspores. Here, we document experimentally the strong but under-explored influence of turbulence on the initiation of dispersal. Flower heads of two thistle species (
Carduus nutans
and
Carduus acanthoides
) with ripe seeds were exposed to series of laminar and turbulent air flows of increasing velocity in a wind tunnel. Seed release increased with wind speeds for both laminar and turbulent flows for both species. However, far more seeds were released, at significantly lower wind speeds, during turbulent flows. These results strongly suggest a need for more quantitative studies of abscission in the field, as well as dispersal models that incorporate variability in the diaspore release phase.
Ancient androdioecy in the freshwater crustaceanEulimnadia
Authors: Weeks Stephen C , Sanderson Thomas F , Reed Sadie K , Zofkova Magdalena , Knott Brenton , Balaraman Usha , Pereira Guido , Senyo Diana M , Hoeh Walter R
Published: June 2007

Among the variety of reproductive mechanisms exhibited by living systems, one permutation—androdioecy (mixtures of males and hermaphrodites)—is distinguished by its rarity. Models of mating system evolution predict that androdioecy should be a brief stage between hermaphroditism and dioecy (separate males and females), or vice versa. Herein we report evidence of widespread and ancient androdioecy in crustaceans in the genusEulimnadia, based on observations of over 33 000 shrimp from 36 locations from every continent except Antarctica. Using phylogenetic, biogeographical and palaeontological evidence, we infer that androdioecy inEulimnadiahas persisted for 24–180 million years and has been maintained through multiple speciation events. These results suggest that androdioecy is a highly successful aspect of the life history of these freshwater crustaceans, and has persisted for orders of magnitude longer than predicted by current models of this rare breeding system.
Predation risk induces changes in nest-site selection and clutch size in the Siberian jay
Authors: Eggers Sönke , Griesser Michael , Nystrand Magdalena , Ekman Jan
Published: June 2007

Life-history theory predicts that an individual should reduce its reproductive efforts by laying a smaller clutch size when high risk of nest predation reduces the value of current reproduction. Evidence in favour of this ‘nest predation hypothesis’, however, is scarce and based largely on correlative analyses. Here, we manipulated perceived risk of nest predation in the Siberian jay
Perisoreus infaustus
using playback involving a mixture of calls by corvid nest predators in the vicinity of nest sites. In response to being exposed to this acoustic cue simulating increased risk of nest predation, the jays chose a nest site offering more protective covering and reduced clutch size. This is the first experimental demonstration of clutch size adjustment and nest site selection as a result of phenotypic plasticity in an open nesting passerine reflecting a facultative response to the perceived risk of nest predation.
Behavioural and hormonal responses to predation in female chacma baboons (Papio hamadryas ursinus)
Authors: Engh Anne L , Beehner Jacinta C , Bergman Thore J , Whitten Patricia L , Hoffmeier Rebekah R , Seyfarth Robert M , Cheney Dorothy L
Published: June 2007

In humans, bereavement is associated with an increase in glucocorticoid (GC) levels, though this increase can be mitigated by social support. We examined faecal GC levels and grooming behaviour of free-ranging female baboons to determine whether similar effects were also evident in a non-human species. Females who lost a close relative experienced a significant increase in GC levels in the weeks following their relative's death compared with the weeks before, whereas control females showed no such increase. Despite the fact that females concentrate much of their grooming on close kin, females who lost a close female relative did not experience a decrease in grooming rate and number of grooming partners; instead, both grooming rate and number of grooming partners increased after a relative's death. While the death of a close relative was clearly stressful over the short term, females appeared to compensate for this loss by broadening and strengthening their grooming networks. Perhaps as a result, females' GC levels soon returned to baseline. Even in the presence of familiar troop-mates and other relatives, females experienced a stress response when they lost specific companions, and they apparently sought to alleviate it by broadening and strengthening their social relationships.
Male–male pheromone signalling in a lekking
Drosophila
Authors: Widemo Fredrik , Johansson Björn G
Published: June 2007

Interest in sex pheromones has mainly been focused on mate finding, while relatively little attention has been given to the role of sex pheromones in mate choice and almost none to competition over mates. Here, we study male response to male pheromones in the lekking
Drosophila grimshawi
, where males deposit long-lasting pheromone streaks that attract males and females to the leks and influence mate assessment. We used two stocks of flies and both stocks adjusted their pheromone depositing behaviour in response to experimental manipulation, strongly indicating male ability to distinguish between competitors from qualitative differences in pheromone streaks alone. This is the first example of an insect distinguishing between individual odour signatures. Pheromone signalling influenced competition over mates, as males adjusted their investment in pheromone deposition in response to foreign pheromone streaks. Both sexes adapt their behaviour according to information from olfactory cues in
D. grimshawi
, but the relative benefits from male–female, as compared to male–male signalling, remain unknown. It seems likely that the pheromone signalling system originally evolved for attracting females to leks. The transition to a signalling system for conveying information about individuals may well, however, at least in part have been driven by benefits from male–male signalling.
Introduction. Computational aerodynamics
Authors: Tucker Paul G
Published: June 2007

The wide range of uses of computational fluid dynamics (CFD) for aircraft design is discussed along with its role in dealing with the environmental impact of flight. Enabling technologies, such as grid generation and turbulence models, are also considered along with flow/turbulence control. The large eddy simulation, Reynolds-averaged Navier–Stokes and hybrid turbulence modelling approaches are contrasted. The CFD prediction of numerous jet configurations occurring in aerospace are discussed along with aeroelasticity for aeroengine and external aerodynamics, design optimization, unsteady flow modelling and aeroengine internal and external flows. It is concluded that there is a lack of detailed measurements (for both canonical and complex geometry flows) to provide validation and even, in some cases, basic understanding of flow physics. Not surprisingly, turbulence modelling is still the weak link along with, as ever, a pressing need for improved (in terms of robustness, speed and accuracy) solver technology, grid generation and geometry handling. Hence, CFD, as a truly predictive and creative design tool, seems a long way off. Meanwhile, extreme practitioner expertise is still required and the triad of computation, measurement and analytic solution must be judiciously used.
Current trends in modelling research for turbulent aerodynamic flows
Authors: Gatski Thomas B , Rumsey Christopher L , Manceau Rémi
Published: June 2007

The engineering tools of choice for the computation of practical engineering flows have begun to migrate from those based on the traditional Reynolds-averaged Navier–Stokes approach to methodologies capable, in theory if not in practice, of accurately predicting some instantaneous scales of motion in the flow. The migration has largely been driven by both the success of Reynolds-averaged methods over a wide variety of flows and the inherent limitations of the method itself. Practitioners, emboldened by their ability to predict a wide variety of statistically steady equilibrium turbulent flows, have now turned their attention to flow control and non-equilibrium flows, i.e. separation control. This review gives some current priorities in traditional Reynolds-averaged modelling research as well as some methodologies being applied to a new class of turbulent flow control problem.
A deterministic model for the sublayer streaks in turbulent boundary layers for application to flow control
Authors: Carpenter Peter W , Kudar Karen L , Ali Reza , Sen Pradeep K , Davies Christopher
Published: June 2007

We present a relatively simple, deterministic, theoretical model for the sublayer streaks in a turbulent boundary layer based on an analogy with Klebanoff modes. Our approach is to generate the streamwise vortices found in the buffer layer by means of a vorticity source in the form of a fictitious body force. It is found that the strongest streaks correspond to a spanwise wavelength that lies within the range of the experimentally observed values for the statistical mean streak spacing. We also present results showing the effect of streamwise pressure gradient, Reynolds number and wall compliance on the sublayer streaks. The theoretical predictions for the effects of wall compliance on the streak characteristics agree well with experimental data. Our proposed theoretical model for the quasi-periodic bursting cycle is also described, which places the streak modelling in context. The proposed bursting process is as follows: (i) streamwise vortices generate sublayer streaks and other vortical elements generate propagating plane waves, (ii) when the streaks reach a sufficient amplitude, they interact nonlinearly with the plane waves to produce oblique waves that exhibit transient growth, and (iii) the oblique waves interact nonlinearly with the plane wave to generate streamwise vortices; these in turn generate the sublayer streaks and so the cycle is renewed.
Computational aeroelastic modelling of airframes and turbomachinery: progress and challenges
Authors: Bartels R.E , Sayma A.I
Published: June 2007

Computational analyses such as computational fluid dynamics and computational structural dynamics have made major advances towards maturity as engineering tools. Computational aeroelasticity (CAE) is the integration of these disciplines. As CAE matures, it also finds an increasing role in the design and analysis of aerospace vehicles. This paper presents a survey of the current state of CAE with a discussion of recent research, success and continuing challenges in its progressive integration into multidisciplinary aerospace design. It approaches CAE from the perspective of the two main areas of application: airframe and turbomachinery design. An overview will be presented of the different prediction methods used for each field of application. Differing levels of nonlinear modelling will be discussed with insight into accuracy versus complexity and computational requirements. Subjects will include current advanced methods (linear and nonlinear), nonlinear flow models, use of order reduction techniques and future trends in incorporating structural nonlinearity. Examples in which CAE is currently being integrated into the design of airframes and turbomachinery will be presented.
Design search and optimization in aerospace engineering
Authors: Keane A.J , Scanlan J.P
Published: June 2007

In this paper, we take a design-led perspective on the use of computational tools in the aerospace sector. We briefly review the current state-of-the-art in design search and optimization (DSO) as applied to problems from aerospace engineering, focusing on those problems that make heavy use of computational fluid dynamics (CFD). This ranges over issues of representation, optimization problem formulation and computational modelling. We then follow this with a multi-objective, multi-disciplinary example of DSO applied to civil aircraft wing design, an area where this kind of approach is becoming essential for companies to maintain their competitive edge.

Our example considers the structure and weight of a transonic civil transport wing, its aerodynamic performance at cruise speed and its manufacturing costs. The goals are low drag and cost while holding weight and structural performance at acceptable levels. The constraints and performance metrics are modelled by a linked series of analysis codes, the most expensive of which is a CFD analysis of the aerodynamics using an Euler code with coupled boundary layer model. Structural strength and weight are assessed using semi-empirical schemes based on typical airframe company practice. Costing is carried out using a newly developed generative approach based on a hierarchical decomposition of the key structural elements of a typical machined and bolted wing-box assembly.

To carry out the DSO process in the face of multiple competing goals, a recently developed multi-objective probability of improvement formulation is invoked along with stochastic process response surface models (Krigs). This approach both mitigates the significant run times involved in CFD computation and also provides an elegant way of balancing competing goals while still allowing the deployment of the whole range of single objective optimizers commonly available to design teams.
Turbomachinery computational fluid dynamics: asymptotes and paradigm shifts
Authors: Dawes W.N
Published: June 2007

This paper reviews the development of computational fluid dynamics (CFD) specifically for turbomachinery simulations and with a particular focus on application to problems with complex geometry. The review is structured by considering this development as a series of paradigm shifts, followed by asymptotes. The original S1–S2 blade–blade-throughflow model is briefly described, followed by the development of two-dimensional then three-dimensional blade–blade analysis. This in turn evolved from inviscid to viscous analysis and then from steady to unsteady flow simulations. This development trajectory led over a surprisingly small number of years to an accepted approach—a ‘CFD orthodoxy’.

A very important current area of intense interest and activity in turbomachinery simulation is in accounting for real geometry effects, not just in the secondary air and turbine cooling systems but also associated with the primary path. The requirements here are threefold: capturing and representing these geometries in a computer model; making rapid design changes to these complex geometries; and managing the very large associated computational models on PC clusters. Accordingly, the challenges in the application of the current CFD orthodoxy to complex geometries are described in some detail.

The main aim of this paper is to argue that the current CFD orthodoxy is on a new asymptote and is
not
in fact suited for application to complex geometries and that a paradigm shift must be sought. In particular, the new paradigm must be geometry centric and inherently parallel without serial bottlenecks. The main contribution of this paper is to describe such a potential paradigm shift, inspired by the animation industry, based on a fundamental shift in perspective from explicit to implicit geometry and then illustrate this with a number of applications to turbomachinery.
Computational fluid dynamics for turbomachinery internal air systems
Authors: Chew John W , Hills Nicholas J
Published: June 2007

Considerable progress in development and application of computational fluid dynamics (CFD) for aeroengine internal flow systems has been made in recent years. CFD is regularly used in industry for assessment of air systems, and the performance of CFD for basic axisymmetric rotor/rotor and stator/rotor disc cavities with radial throughflow is largely understood and documented. Incorporation of three-dimensional geometrical features and calculation of unsteady flows are becoming commonplace. Automation of CFD, coupling with thermal models of the solid components, and extension of CFD models to include both air system and main gas path flows are current areas of development. CFD is also being used as a research tool to investigate a number of flow phenomena that are not yet fully understood. These include buoyancy-affected flows in rotating cavities, rim seal flows and mixed air/oil flows. Large eddy simulation has shown considerable promise for the buoyancy-driven flows and its use for air system flows is expected to expand in the future.
Biological matrices and bionanotechnology
Authors: Taylor Patricia M
Published: June 2007

A crucial step towards the goal of tissue engineering a heart valve will be the choice of scaffold onto which an appropriate cell phenotype can be seeded. Successful scaffold materials should be amenable to modification, have a controlled degradation, be compatible with the cells, lack cytotoxicity and not elicit an immune or inflammatory response. In addition, the scaffold should induce appropriate responses from the cells seeded onto it, such as cell attachment, proliferation and remodelling capacity, all of which should promote the formation of a tissue construct that can mimic the structure and function of the native valve. This paper discusses the various biological scaffolds that have been considered and are being studied for use in tissue engineering a heart valve. Also, strategies to enhance the biological communication between the scaffold and the cells seeded onto it as well as the use of bionanotechnology in the manufacture of scaffolds possessing the desired properties will be discussed.
Heart valve macro- and microstructure
Authors: Misfeld Martin , Sievers Hans-Hinrich
Published: June 2007

Each heart valve is composed of different structures of which each one has its own histological profile. Although the aortic and the pulmonary valves as well as the mitral and the tricuspid valves show similarities in their architecture, they are individually designed to ensure optimal function with regard to their role in the cardiac cycle.

In this article, we systematically describe the structural elements of the four heart valves by different anatomical, light- and electron-microscopic techniques that have been presented. Without the demand of completeness, we describe main structural features that are in our opinion of importance in understanding heart valve performance. These features will also have important implications in the treatment of heart valve disease. They will increase the knowledge in the design of valve substitutes or partial substitutes and may participate to improve reconstructive techniques. In addition, understanding heart valve macro- and microstructure may also be of benefit in heart valve engineering techniques.
On the bootstrap confidence intervals of the capability index Cpk for multiple process streams
Authors: Wang Dja‐Shin , Koo Tong‐Yuan , Chou Chao‐Yu
Published: July 2007

Purpose

The present paper aims to present the results of a simulation study on the behavior of the four 95 percent bootstrap confidence intervals for estimating Cpk when collected data are from a multiple streams process.

Design/methodology/approach

A computer simulation study is developed to present the behavior of four 95 percent bootstrap confidence intervals, i.e. standard bootstrap (SB), percentile bootstrap (PB), biased‐corrected percentile bootstrap (BCPB), and biased‐corrected and accelerated (BCa) bootstrap for estimating the capability index Cpk of a multiple streams process. An analysis of variance using two factorial and three‐stage nested designs is applied for experimental planning and data analysis.

Findings

For multiple process streams, the relationship between the true value of Cpk and the required sample size for effective experiment is presented. Based on the simulation study, the two‐stream process always gives a higher coverage percentage of bootstrap confidence interval than the four‐stream process. Meanwhile, BCPB and BCa intervals lead to better coverage percentage than SB and PB intervals.

Practical implications

Since a large number of process streams decreases the coverage percentage of the bootstrap confidence interval, it may be inappropriate to use the bootstrap method for constructing the confidence interval of a process capability index as the number of process streams is large.

Originality/value

The present paper is the first work to explore the behavior of bootstrap confidence intervals for estimating the capability index Cpk of a multiple streams process. It is concluded that the number of process streams definitively affects the performance of bootstrap methods.
Identification of crystallization kinetics parameters by genetic algorithm in non‐isothermal conditions
Authors: Smirnova J. , Silva L. , Monasse B. , Haudin J‐M. , Chenot J‐L.
Published: July 2007

Purpose

This paper sets out to show the feasibility of the genetic algorithm inverse method for the determination of the parameters of crystallization kinetics laws in isothermal and non‐isothermal conditions, using multiple experiments.

Design/methodology/approach

The mathematical model for crystallization kinetics determination and the numerical methods of its resolution are introduced. Crystallization kinetic parameters determined by approximate physical analysis and the inverse genetic algorithm method are presented. Injection molding simulations taking into account crystallization are performed using the finite element method.

Findings

It is necessary to perform the optimization on two parameters, transformed volume fraction and number of spherulites to obtain correct results. It is possible to use results from different samples, in spite of the dispersion of some values.

Research limitations/implications

Experimental data for isothermal and non‐isothermal conditions were used and obtained good results for the parameters of crystallization kinetics laws from which the evolutions of overall crystallization kinetics and crystalline microstructure were deduced. Nevertheless, the dispersion of the experimental data concerning the number of spherulites obtained with different samples is important. The evolution of the number of spherulites is required for the optimization to get correct results.

Practical implications

An important result of this work is that the genetic algorithm optimization can be applied to this problem where the experiments cannot be performed with a single sample and the experimental data for the number of spherulites have low precision. Even if only the crystallization kinetics was considered, the feasibility in molding simulation has been shown.

Originality/value

Simulation of crystallization in injection molding is very important for a later prediction of the end‐use properties.
The storage constrained, inbound inventory routing problem
Authors: Stacey Jennifer , Natarajarathinam Malini , Sox Charles
Published: July 2007

Purpose

This paper aims to describe the storage constrained, inbound inventory routeing problem and presents bounds and heuristics for solutions to this problem. It also seeks to analyze various characteristics of this problem by comparing the solutions generated by the two proposed heuristics with each other and with the lower bound solutions.

Design/methodology/approach

The proposed heuristics use a sequential decomposition strategy for generating solutions for this problem. These heuristics are evaluated on a set of problem instances which are based on an actual application in the automotive manufacturing industry.

Findings

The storage space clearly has a significant effect on both the routeing and inventory decisions, and there are complex and interesting interactions between the problem factors and performance measures.

Practical implications

Facility design decisions for the storage of inbound materials should carefully consider the impact of storage space on transportation and logistics costs.

Originality/value

This problem occurs in a number of different industrial applications while most of the existing literature addresses outbound distribution. Other papers that address similar problems do not consider all of the practical constraints in the problem or do not adequately benchmark and analyze their proposed solutions.
Growth hormone (GH) replacement decreases serum total and LDL‐cholesterol in hypopituitary patients on maintenance HMG CoA reductase inhibitor (statin) therapy
Authors: Monson John P. , Jönsson Peter , Koltowska‐Häggström Maria , Kourides Ione
Published: June 2007

Objective  Adult onset GH deficiency (GHD) is characterized by abnormalities of serum lipoprotein profiles and GH replacement results in favourable alterations in serum total and low density lipoprotein (LDL)‐cholesterol. Preliminary evidence has indicated that the effect of GH replacement in this respect may be additive to that of HMG CoA reductase inhibitor (statin) therapy. We have examined this possibility during prospective follow‐up of adult onset hypopituitary patients enrolled in KIMS (Pfizer International Metabolic Database), a pharmacoepidemiological study of GH replacement in adult hypopituitary patients.

Design  Lipoprotein profiles were measured centrally at baseline and after 12 months GH replacement therapy.

Patients  Sixty‐one hypopituitary patients (30 male, 31 female) on maintenance statin therapy (mean 2·5 ± 2·7 SD years before GH) (statin group – SG) and 1247 (608 male, 639 female) patients not on hypolipidaemic therapy (nonstatin group – NSG) were studied. All patients were naïve or had not received GH replacement during the 6 months prior to study. Patients who developed diabetes mellitus during the first year of GH therapy or in the subsequent year and those with childhood onset GHD were excluded from this analysis. An established diagnosis of diabetes mellitus was present in 18% SG and 4·4% NSG at baseline.

Measurements  Serum concentrations of total, high density lipoprotein (HDL)‐cholesterol, triglycerides and IGF‐I were measured centrally in all patients and LDL‐cholesterol was estimated using Friedewald's formula.

Results  The relative frequency of various statin use was simvastatin 52% (15·8 ± 8·1 mg, mean ± SD), atorvastatin 30% (14·4 ± 7·8 mg), pravastatin 9·8% (31·6 mg ± 13·9 mg), lovastatin 6·6% (17·5 ± 5 mg) and fluvastatin 1·6% (40 mg). Baseline serum total and LDL‐cholesterol (mean ± SD) were 5·2 ± 1·4 and 3·1 ± 1·3 mmol/l in SG and 5·8 ± 1·2 and 3·7 ± 1·0 mmol/l in NSG, respectively (P < 0·0001, SG vs. NSG). After 12 months GH replacement (SG: 0·32 ± 0·17 mg/day; NSG: 0·38 ± 0·1 mg/day) serum total and LDL‐cholesterol decreased by a mean (±SD) of 0·48 (± 1·25) mmol/l (P < 0·0004) and 0·53 (± 1·08) mmol/l (P < 0·0001) in SG and by 0·30 (± 0·89) mmol/l (P < 0·0001) and 0·28 (± 0·80) mmol/l (P < 0·0001) in NSG, respectively. There were no significant changes in HDL‐cholesterol or triglycerides in either group (SG vs. NSG: NS). A relationship between LDL‐cholesterol at baseline and the decrease in LDL‐cholesterol after 12 months GH was evident in both groups (SG: R = –0·54, P < 0·001; NSG: R = –0·4, P < 0·001) and a similar relationship for cholesterol was observed.

Conclusions  These data indicate that GH replacement exerts additional beneficial effects on lipoprotein profiles in patients on maintenance statin therapy, confirming that the effects of these interventions are complementary rather than exclusive.
Can intra‐specific genetic variation in arbuscular mycorrhizal fungi (Glomus etunicatum) affect a mesophyll‐feeding herbivore (Tupiocoris notatusDistant)?
Authors: WOOLEY STUART C. , PAINE TIMOTHY D.
Published: June 2007

Abstract1. Arbuscular mycorrhizal fungal (AMF) infection can have negative, positive or neutral effects on insect herbivore populations, but patterns are difficult to predict.

2. Intra‐specific genetic variation in nutrient uptake ability between fungal isolates may also have indirect effects on insect herbivores due to changes in plant quality. In preliminary studies mirid (Tupiocoris notatus) populations were significantly reduced on tobacco (Nicotiana rustica) colonised by AMF but it was unknown if same‐species fungal isolates differed in their effect.

3. An experiment was performed as a first test of the effect of intra‐specific genetic variation in the mycorrhizal fungusGlomus etunicatumon mirid nymphal population structure, dynamics, and growth rate.

4. Mirid nymphal populations were lower on mycorrhizal fungal‐infected plants. Population size, however, did not differ between the mycorrhizal isolates. While no statistical difference in population between isolates was found, one isolate consistently had 1.7–2.4 times lower mirid populations compared with the controls, indicating that the magnitude of effect is different between mycorrhizal isolates.

5. The significantly negative effect of AMF on mirid populations likely resulted from AMF‐induced changes in plant quality (e.g. increased defence). This study lends further support to recent demonstrations that below‐ground symbionts significantly influence above‐ground processes. In addition, mycorrhizal fungi can affect insect population structure, which may have consequences for future herbivory.
Successional phases and species replacements in freshwater rock pools: towards a biological definition of ephemeral systems
Authors: JOCQUÉ MERLIJN , RIDDOCH BRUCE J. , BRENDONCK LUC
Published: June 2007

1. In temporary aquatic habitats, time is probably the dominant environmental factor affecting community composition, mainly by setting constraints on colonization success and the replacement of taxa over time. The mechanism and effect of a decreasing inundation period on community development, mostly in terms of truncation, are still poorly documented. The permanent and ephemeral components of temporary communities are expected to be differently influenced by the degree of persistence of the habitat.

2. To study the effect of time on invertebrate community assembly and dynamics in a short duration type of temporary aquatic habitat, we monitored 16 ephemeral rock pools which persisted from less than a week to about 1 month at two rock pool sites in semi‐arid south‐eastern Botswana. Data were collected every 2 days during a full inundation cycle.

3. All communities were initially assembled by permanent residents recolonizing the habitat from egg banks and were later joined by actively dispersing ephemeral taxa. Species replacements only occurred in two pools. Concurrent with a decrease in the densities of Branchipodopsis wolfi, population sizes of Leberis sp. and Culicidae (Aedes sp. and Anopheles sp.) increased in these pools. Although it was possible to distinguish two successive phases at one rock pool site, community assembly was generally a gradual process determined by dispersal strategies of the inhabitants. Additional rains after initial filling triggered dispersal by ephemeral taxa, mainly Micronecta youngiana and Hydroglyphus infirmus, and positively influenced colonization success.

4. Decreasing persistence shortens community development down to a critical point below which lack of time eliminates the possibility of species replacement. Based on these findings, we define ephemeral waters as aquatic habitats lacking species replacements. Other temporary water types have a relatively longer persistence, permitting successional replacement of species.