bluuebunny/crossref_metadata_2025_split huggingface dataset:
Minimal access thyroid surgery: Is it feasible, is it appropriate?
Authors: Sackett Wendy R. , Barraclough Bruce H. , Sidhu Stan , Reeve Tom S. , Delbridge Leigh W. 
Published: March 2003

Background:  Reports of minimal access thyroid surgery (MATS) using various techniques have recently appeared. This study examined the feasibility of MATS using either a lateral ‘focused’ or endoscopically assisted approach.Methods:  The study group comprised all patients undergoing minimally invasive parathyroidectomy (MIP) during the period May 1998 to April 2002 in whom a concomitant thyroid procedure was undertaken. All procedures were performed either through a 2‐cm lateral cervical incision (n = 19) or endoscopically (n = 7).Results:  Twenty‐six patients underwent thyroid surgery, consisting of either local excision of a thyroid nodule (n = 25) or hemi­thyroidectomy (n = 1). In 13 patients the nodule was incidentally discovered, in four patients removal of the parathyroid necessitated partial thyroidectomy, and in nine patients the lesion identified by preoperative parathyroid localization proved to be a thyroid nodule. There were no permanent complications in the study group. Two patients required drainage of a haematoma. The final pathology of all 26 cases revealed benign nodular thyroid disease.Conclusion:  Thyroid surgery can safely be performed as a minimally invasive procedure. Minimal access thyroid surgery is therefore a feasible option for selected patients. The question remains to be answered as to whether this surgical approach is appropriate treatment for nodular thyroid disease.
Extra‐nodal lymphoma presenting as a mimic of soft‐tissue sarcoma
Authors: Knowles Brett , Serpell Jonathan W. 
Published: March 2003

Background:  A variety of soft‐tissue tumours result in soft‐tissue masses, which are all differential diagnoses of soft‐tissue sar­comas. A rare cause is extra‐nodal lymphoma which, unlike a soft‐tissue sarcoma which it mimics, should not be excised, but rather treated by chemotherapy and/or radiotherapy. The aim of the present study was to identify clinical, radiological, biopsy and management features of lymphoma when presenting as a soft‐tissue mass.Methods:  A review of 17 cases of soft‐tissue lymphoma presenting as a soft‐tissue mass from a total database of 295 soft‐tissue tumours was undertaken. Lymphomas arising in cervical, axillary and inguinal nodes were excluded.Results:  All patients presented with a soft‐tissue mass but none had the symptoms of lymphoma. Computed tomography scanning identified seven (54%) of 13 with regional lymphadenopathy, six (46%) of 13 with encasement of major vascular structures and three with invasion across major soft‐tissue boundaries. Core biopsy established a diagnosis in 13 patients (sensitivity 93%). All patients were treated with either chemotherapy and/or radiotherapy and all are alive with a mean follow up of 19 months. None underwent major resectional surgery.Conclusion:  The present series highlights a rare subgroup of patients with extra‐nodal soft‐tissue lymphoma mimicking soft‐tissue sarcoma. Core biopsy is accurate in their diagnosis. Computed tomography scanning may show features suggesting the diagnosis.
Thoracoscopic talc pleurodesis for malignant pleural effusion
Authors: Love David , White Dean , Kiroff George 
Published: March 2003

Background:  Malignant pleural effusion (MPE) is a common and distressing condition at the end of life for many patients with disseminated cancer. The challenge for the surgeon lies in managing this problem in order to deliver the most effective palliation with the least impact on the limited time available to these patients.Methods:  Herein is reported a retrospective review of outcomes for a consecutive series of 66 MPE (61 patients) treated over a 5‐year period from 1995 to 2000. A standard operative technique involving a single‐lung anaesthetic and two‐port thoracoscopy was employed. Outcomes were determined by contacting the referring practitioner or the patients themselves. Principal outcome measures included time to recurrence of the effusion and survival.Results:  Complete follow up was achieved for 60 MPE (55 patients; five of whom were treated for metachronous, bilateral ­disease). The three most common primary sites were breast, lung and mesothelial tissue. The planned procedure was not completed in two cases due to encasement of the underlying lung by tumour. Primary failure (immediate recurrence of the effusion) occurred in six cases. Delayed recurrence of the effusion occurred in a further 23 MPE resulting in complete control in 31 cases (52%) until death. Overall median survival was 220 days and the 30‐day mortality was 0.Conclusions:  Complete and permanent control of a malignant effusion is difficult to achieve. Management based on thoracoscopy and talc insufflation produces satisfactory results with an acceptable morbidity and no early mortality. The ability to inspect the pleural space, break down adhesions and completely drain pockets of fluid to achieve complete lung expansion probably contributes to this.
Optimizing glycoprotein IIb/IIIa inhibition: lessons from recent randomized controlled trials
Authors: Chew D. P. , Bhatt D. L. 
Published: March 2003

AbstractRecent randomized clinical trials with intravenous glycoprotein IIb/IIIa inhibition have provided unanticipated results, thereby questioning their role as empirical medical management for acute coronary syndromes. The lack of benefit with abciximab observed in Global Utilization of Strategies to Open Occluded Coronary Arteries IV is somewhat inconsistent with the benefits seen with this agent in coronary intervention, and the benefits of an early invasive approach incorporating tirofiban seen within Treat Angina with Aggrastat and determine Cost of Therapy with an Invasive or Conservative Strategy Thrombolysis in Myocardial Infraction 18. Additionally, a direct ‘head‐to‐head’ comparative study of abciximab and tirofiban within the setting of percutaneous coronary intervention demonstrates clinically relevant superiority with abciximab with respect to 30‐day outcomes.These findings indicate that the interaction between glycoprotein IIb/IIIa inhibition and clinical outcome in the setting of coronary instability and mechanical plaque disruption is more complex than initially perceived. Hence, although an abundance of evidence details the efficacy of these agents, their optimal clinical application remains somewhat challenging in light of these recent data. However, within the context of previous trial experience, the current evidence highlights several key aspects of glycoprotein IIb/IIIa inhibitor therapy that may be associated with improved patient outcomes. In particular, these trials indicate: (i) the importance of selecting high‐risk patients in whom substantial clinical benefit is evident, (ii) the incorporation of these agents into an early invasive strategy, thereby matching the timing of vascular injury with maximal platelet inhibition and (iii) optimal dosing to achieve the high levels of platelet inhibition that appear to be required for efficacy with these agents. (Intern Med J 2002; 32: 338−345)
Modelling damage accumulation in filled polymers
Authors: Bykov  
Published: March 2003

A variant of the non‐linear endochronic viscoelasticity theory is developed wherein the reduced‐time function depends on a damage parameter, equivalent strains or stresses, as well as on some functions enabling one to distinguish between loading and unloading processes. Some combinations of the first and second invariants of strain and stress tensors are used as the equivalent strains or stresses.The existence of flaws is taken into account by the introduction of special equivalent stresses which are dependent on principal tensile stresses and the characteristics of the material.As a criterion of damage equivalence in non‐linear viscoelastic materials, the condition of a specific dissipation equality is introduced. Experiments for the determination of material functions entering the constitutive equations are outlined.The proposed variant of the theory has made it possible to realistically explain the results of creep and constant loading rate tensile tests and creep tests to rupture under conditions of two‐step loading sequences acting on filled polymeric materials.
Strain rate effects for aluminum and magnesium alloys in finite element simulations of steering wheel armature impact tests
Authors: ALTENHOF W. , AMES W. 
Published: March 2003

ABSTRACTThis paper addresses the strain rate effects for aluminum and magnesium steering wheel armatures when they are subjected to dynamic impact tests. Two geometrically different steering wheel armatures, a three spoke proprietary aluminum alloy armature and a four spoke magnesium alloy (AM50A) armature, underwent experimental impact testing. The testing conditions for each armature were different; testing with the aluminum alloy armature involved impacts with a deformable chestform and the magnesium armature experienced impact tests with a rigid plate. Finite element models of all testing apparatuses were developed for both testing conditions and numerical simulations were conducted based on the experimental method employed. Strain rate effects for the aluminum alloy were considered using the Cowper–Symonds constitutive relation and a Johnson–Cook material law was utilized for the magnesium alloy. Simulations were conducted with and without strain rate effects considered. The comparison between the experimental and numerical methods illustrate that there is only a minor change in the numerical testing results with the inclusion of strain rate effects, however, a better correlation between experimental and numerical methods occurs.
Truncated power laws: a tool for understanding aggregation patterns in animals?
Authors: Sjöberg Mikael , Albrectsen Benedicte , Hjältén Joakim 
Published: March 2003

Statistical distributions like the negative binomial distribution are commonly used to describe aggregation patterns in animals. However, recently it has been suggested that truncated power laws (TPLs) may also be used for this kind of analysis. A TPL consists of two power functions separated by a cut‐off size (C*). The cut‐off size and the slope of power function one (β1) for the smallest group sizes have been suggested to have a biological explanatory value.We applied TPLs to aggregation data of tephritid seed predators on a composite plant, aphids on willows and grey seals on a haulout site. β1 varied between 0.60 and and −0.72, which is higher than predicted. In addition, resource distribution and animal density influenced β1 and C*. This indicates that environmental dimensionality suggested to affect β1 is masked by ecological factors. We conclude that TPLs are useful due to their simplicity and, in comparison with traditional methods, provide additional biologically relevant information. Truncated power laws can therefore prove to be useful in studies of animal behaviour and population dynamics.
Cohort effects and population dynamics
Authors: Lindström Jan , Kokko Hanna 
Published: March 2003

AbstractCohort effects originate from environmental conditions, and can have long‐term consequences for the cohort's performance. It has been proposed that cohort effects tend to increase population fluctuations. However, differences among individuals, which cohort effects introduce into a population, usually have stabilizing effects. There are thus two different predictions regarding the impact of cohort effects on population fluctuations. We argue that it is important to distinguish between environmental variability and its long‐term effects on individual quality, and approach the question with a population model that can include or exclude such effects. We show that the influence of cohort effects depends on the inherent dynamics: cohort effects can have stabilizing effects if dynamics are inherently unstable. However, the most common outcome is destabilization whenever cohort effects act on top of inherently stable dynamics. Intriguingly, both alternatives are due to individual differences affecting the structure of density dependence in a similar way.
Consumer movement through differentially subsidized habitats creates a spatial food web with unexpected results
Authors: Callaway Duncan S. , Hastings Alan 
Published: March 2003

AbstractEnergy and nutrient flow between habitats, or allochthonous input, can have a significant impact on food web dynamics. Previous theory demonstrated that resource abundance decreases in habitats where consumers are subsidized. Here we examine the effect of subsidies that are available in localized parts of a habitat (such as near the shore in a marine‐subsidized terrestrial ecosystem) with a two‐patch model in which consumers move between patches, resources are stationary, and consumers receive the subsidy in only one of the two patches. In contrast to previous theory, our results show that subsidized consumers can increase resource abundance, though only in the subsidized patch. Furthermore, the total resource population responds positively to increasing consumer movement. These results demonstrate the importance of spatial heterogeneity in food web dynamics and the need for further examination of the role of space in multispecies trophic webs.
Minimizing energy expenditure facilitates vertebrate persistence on oceanic islands
Authors: McNab Brian K. 
Published: March 2003

AbstractThe characteristics of terrestrial vertebrates on oceanic islands are examined. They often include a reduced body size, a tolerance of conspecifics, flightlessness, a reduced basal rate of metabolism, and a propensity to enter torpor. On oceanic islands ectotherms frequently replace endotherms. These changes reduce the energy expenditure and resource requirements of vertebrates. Such reductions are permitted by the absence of mammalian predators and facilitate the survival of island endemics in the face of a restricted resource base and a variable environment through an increase in population size. Some insular species increase body size, but this occurs only when the resource base is large, due either to a fortuitously abundant resource, or to the absence of other species that exploit normally abundant resources. Some questions are posed to guide future work. They examine of the characteristics that permit species to disperse over water barriers, the conditions that require a reduction in resource use, the rapidity of response by immigrants to island conditions, whether supertramps show physiological differentiation with respect to island distance or size, and whether island size is absolute or relative to the size of the immigrants.
Opposing clines for high and low temperature resistance in Drosophila melanogaster
Authors: Hoffmann Ary A. , Anderson Alisha , Hallas Rebecca 
Published: March 2003

AbstractIn insects, species comparisons suggest a weak association between upper thermal limits and latitude in contrast to a stronger association for lower limits. To compare this to latitudinal patterns of thermal responses within species, we considered latitudinal variation in heat and cold resistance in Drosophila melanogaster. We found opposing clines in resistance to these temperature extremes in comparisons of 17–24 populations from coastal eastern Australia. Knockdown time following heat shock increased towards the tropics, whereas recovery time following cold shock decreased towards temperate latitudes. Mortality following cold shock also showed a clinal pattern. Clinal associations with latitude were linear and related to minimum temperatures in the coldest month (for cold resistance) and maximum temperatures in the warmest month (for heat resistance). This suggests that within species both high and low temperature responses can vary with latitude as a consequence of direct or indirect effects of selection.
Reproductive timing and individual fitness
Authors: Brommer Jon E. , Merilä Juha , Kokko Hanna 
Published: March 2003

AbstractEstimation of individual fitness – i.e. description of the extent to which an individual's genes are represented in future generations – is a feature central to most evolutionary studies. Lifetime reproductive success (LRS) is a commonly used estimate of individual fitness, but because it is rate‐insensitive (i.e. timing of reproductive events is not incorporated), it may give a biased estimate of fitness when reproductive timing is an important component of fitness. A review of all empirical studies which have used a recently derived, rate‐sensitive estimate of individual fitness, λind revealed that λind ranks the fitness of phenotypes differently from LRS, and that this difference may lead to different conclusions about strength of selection acting on phenotypic traits. However, although λind may be a better estimate of individual fitness than LRS in certain situations (e.g. in growing populations), its application is not always unproblematic. For instance, in contrast to rate‐insensitive estimates of individual fitness, the λind is sensitive to the age at which offspring are censused and there is little consensus among published studies on when offspring should be counted. Further, rate‐sensitivity does not necessarily improve a fitness estimate in spatio‐temporal variable environments. We suggest that the ultimate test on the applicability of λind vs. LRS as practical measures of individual fitness in quantifying selection should come from studies which correlate these estimates with actual number of descendants left more than one generation further in future.
Unusual synchronization of Red Sea fish energy expenditures
Authors: Stone Lewi , He DaiHai , Becker K. , Fishelson Lev 
Published: March 2003

AbstractThe highly gregarious goat fish Parupeneus forskalii found in the Red Sea at Eilat, Israel exhibit highly synchronous swimming and feeding activity. Five fish were studied under controlled conditions and highly resolved time‐series of their energy expenditures were measured. All fish demonstrated strong phase synchronization in that their activity levels, although erratic in time and intensity, were collectively coordinated and peaked simultaneously together. The synchronization of these wildly varying, and possibly chaotic signals of energy expenditures, were quantified using phase analysis. We suggest that, ecologically, this collective synchronization is a strategy that increases food‐catch.
Parasite evolution and extinctions
Authors: Boots Michael , Sasaki Akira 
Published: March 2003

AbstractWe examine the evolution of diseases that show the frequency‐dependent transmission process that is commonly applied to sexually and vector‐transmitted infections. As is commonly found, the basic reproductive ratio (R0) of the parasite is maximized by evolution. This has important implications, as it implies that for a wide range of circumstances diseases that show frequency‐dependent transmission may be selected to evolve towards driving their hosts to extinction. This contrasts with the results obtained in spatially explicit models where although parasite‐driven host extinction may occur, it is unlikely to evolve. We further show that an evolutionary constraint between transmission and virulence is required for evolution to lead to an endemic coexistence of both the host and the disease. Furthermore, this constraint needs to be saturating, such that transmission is ‘bought’ at an increasing cost in terms of virulence, to avoid evolution to extinction.
Positive effects of plant species diversity on productivity in the absence of legumes
Authors: Van Ruijven Jasper , Berendse Frank 
Published: March 2003

AbstractWe investigated the effect of species richness on productivity in randomly assembled grassland communities without legumes. Aboveground biomass increased with increasing species richness and different measures of complementarity showed strong increases with plant species richness. Increasing productivity could not be attributed to a relative increase of highly productive species. Instead, the increase appeared to be caused by the increased performance of several low‐productive species. Our results provide evidence that niche complementarity can strongly increase productivity in grasslands, although the communities contained only grasses and forbs.
Phenotypic integration: studying the ecology and evolution of complex phenotypes
Authors: Pigliucci Massimo 
Published: March 2003

AbstractPhenotypic integration refers to the study of complex patterns of covariation among functionally related traits in a given organism. It has been investigated throughout the 20th century, but has only recently risen to the forefront of evolutionary ecological research. In this essay, I identify the reasons for this late flourishing of studies on integration, and discuss some of the major areas of current endeavour: the interplay of adaptation and constraints, the genetic and molecular bases of integration, the role of phenotypic plasticity, macroevolutionary studies of integration, and statistical and conceptual issues in the study of the evolution of complex phenotypes. I then conclude with a brief discussion of what I see as the major future directions of research on phenotypic integration and how they relate to our more general quest for the understanding of phenotypic evolution within the neo‐Darwinian framework. I suggest that studying integration provides a particularly stimulating and truly interdisciplinary convergence of researchers from fields as disparate as molecular genetics, developmental biology, evolutionary ecology, palaeontology and even philosophy of science.
Effects of O2 and CH4 on presence and activity of the indigenous methanotrophic community in rice field soil
Authors: Henckel Thilo , Roslev Peter , Conrad Ralf 
Published: March 2003

The activity and distribution of methanotrophs in soil depend on the availability of CH4 and O2. Therefore, we investigated the activity and structure of the methanotrophic community in rice field soil under four factorial combinations of high and low CH4 and O2 concentrations. The methanotrophic population structure was resolved by denaturant gradient gel electrophoresis (DGGE) with different PCR primer sets targeting the 16S rRNA gene, and two functional genes coding for key enzymes in methanotrophs, i.e. the particulate methane monooxygenase (pmoA) and the methanol dehydrogenase (mxaF). Changes in the biomass of type I and II methanotrophic bacteria in the rice soil were determined by analysis of phospholipid‐ester‐linked fatty acid (PLFA) biomarkers. The relative contribution of type I and II methanotrophs to the measured methane oxidation activity was determined by labelling of soil samples with 14CH4 followed by analysis of [14C]‐PLFAs. CH4 oxidation was repressed by high O2 (20.5%), and enhanced by low O2 (1%). Depending on the CH4 and O2 mixing ratios, different methanotrophic communities developed with a higher diversity at low than at high CH4 concentration as revealed by PCR‐DGGE. However, a prevalence of type I or II populations was not detected. The [14C]‐PLFA fingerprints, on the other hand, revealed that CH4 oxidation activity was dominated by type I methanotrophs in incubations with low CH4 mixing ratios (1000 p.p.m.v.) and during initiation of CH4 consumption regardless of O2 or CH4 mixing ratio. At high methane mixing ratios (10 000 p.p.m.v.), type I and II methanotrophs contributed equally to the measured CH4 metabolism. Collectively, type I methanotrophs responded fast and with pronounced shifts in population structure and dominated the activity under all four gas mixtures. Type II methanotrophs, on the other hand, although apparently more abundant, always present and showing a largely stable population structure, became active later and contributed to CH4 oxidation activity mainly under high CH4 mixing ratios.