bluuebunny/crossref_metadata_2025 huggingface dataset:
Thoracoscopy‐assisted mini‐open surgery for anterior column reconstruction in thoracic spinal tuberculosis
Authors: Lv Guo‐hua , Wang Bing , Li Jing , Liu Wei‐dong , Yin Gang‐hui , Ma Ze‐min
Published: October 2009

Objective:  To evaluate the clinical effects of thoracoscopy‐assisted mini‐open surgery for anterior column reconstruction in thoracic spinal tuberculosis.

Methods:  Fifty‐eight patients, 35 men and 23 women, aged 39.2 (range, 19–60) years with thoracic spinal tuberculosis with an average kyphotic angle of 29.2° (range, 18°–42°) underwent thoracoscopy‐assisted mini‐open surgeries, including thorough debridement and anterior spinal reconstruction. According to the Frankel Grading system, preoperative neurological function was judged as Grade B in 3 cases, Grade C in 7, Grade D in 28, and Grade E in 20. All patients were followed up for an average of 4.6 years. Outcomes were evaluated retrospectively.

Results:  Surgery was accomplished successfully in all cases. The average operation time was 230 min (range, 180–320 min), the average intraoperative blood loss 570 ml (range, 350–1200 ml), and the mean drainage duration 3.6 days (3–5 days). Complications occurred in 19 patients (32.8%). Neurological improvement of one to three grades had occurred in 29 patients by final follow‐up. The average correction rate of the kyphotic angle was 36.4%, and no obvious correction loss was detected during follow‐up. No recurrent tuberculosis was found in the group.

Conclusions:  Thoracoscopy‐assisted mini‐open surgery provides a simple, safe, effective, and practical technology with minimal invasiveness for the treatment of thoracic spinal tuberculosis.
Imaging study of wedge changes in the vertebral bodies and intervertebral discs in adolescent idiopathic scoliosis
Authors: Xu Hong‐guang , Qiu Gui‐xing , Wang Yi‐peng , Zhang Jian‐guo , Liu Yong , Wu Zhi‐hong
Published: October 2009

Objective:  To observe wedge changes in the vertebral bodies and intervertebral discs in progressive adolescent idiopathic scoliosis before and after conservative treatment with braces, and to explore the correlation between wedge changes in the vertebral bodies or intervertebral discs and scoliosis curves.

Methods:  Thirty‐seven consecutive patients with adolescent idiopathic scoliosis were included in this study from June 2001 to August 2003. There were 31 female and 6 male patients, with an average age of 14.9 years. According to the Peking Union Medical College (PUMC) grading system, eight cases were Ia, three Ib, five Ic, twelve IIb1, three IIb2, three IIc1, one IIc3, and two IId1. Wedge changes in the vertebral bodies and intervertebral discs, and the scoliosis angles were measured by radiographic evaluation before conservative treatment with braces and before surgery.

Results:  In the mature patients (Risser sign IV, V, menarche two years or more previously), wedge changes in the vertebral bodies and intervertebral discs worsened with curve progression, and were poorly correlated with the degree of curve (r= 0.17). But in the developmentally immature patients (Risser sign 0–III, pre‐menarche), there was a significant correlation with the degree of curve (r= 0.69). Wedge changes in the vertebral bodies and intervertebral discs worsened with curve progression, and were significantly correlated with the degree of curve.

Conclusion:  Wedge changes in the vertebral bodies and intervertebral discs have a positive correlation with degree of curve, which indicates that asymmetric growth of the cartilaginous endplate might be the primary cause of wedge change in the vertebral bodies.
Ectopic osteogenesis of mouse bone marrow stromal cells transfected with BMP 2/VEGF165 genes in vivo
Authors: Tian Xiao‐bin , Sun Li , Yang Shu‐hua , Fu Ru‐yin , Wang Lei , Lu Tin‐shen , Zhang Yu‐kun , Fu De‐hao
Published: October 2009

Objective:  To evaluate the osteogenic efficacy of mouse bone marrow stromal cells (mBMSC) transfected with bone morphogenetic protein 2 (BMP2) and vascular endothelial growth factor 165 (VEGF165) genes.

Methods:  pIRES‐BMP2‐VEGF165 plasmid DNA was introduced into the mBMSC using a liposome‐mediated method. The expression of BMP2 and VEGF165 genes was assessed by reverse transcription‐polymerase chain reaction (RT‐PCR) and immunohistochemical analysis. Transfected cells were injected into the thigh muscle pouches of four nude mice. The osteoinductivity activity of the transfected cells was evaluated by radiographic and histological analysis at 4 weeks after injection.

Results:  The mRNA and proteins of both BMP2 and VEGF165 were successfully expressed in mBMSC as confirmed by RT‐PCR and immunohistochemical analysis. Ectopically formed bone tissue was clearly observed at 4 weeks after cell injection in the thigh muscle pouches of the nude mice.

Conclusion:  mBMSC transfected with BMP2 and VEGF165 genes can induce ectopic osteogenesis.
One‐stage anterior release and reduction with posterior fusion for treatment of irreducible atlantoaxial dislocation
Authors: Hao Ding‐jun , He Bao‐rong , Wu Qi‐ning
Published: October 2009

Objective:  To analyze the approach and feasibility of one‐stage anterior release and reduction with posterior fusion for irreducible atlantoaxial dislocation.

Methods:  Ten male and 6 female patients, with an average age of 36 years, including 13 patients with old trauma, 2 with rheumatoid disease, and 1 with os odontoideum were studied. Anterior release and reduction was performed in the supine position. The atlas and vertebra dentate were fixed posteriorly and fused by one stage.

Results:  All patients were followed up from 15 to 40 months (mean, 23 months), and all gained anatomic reduction and bone fusion. Six months postoperatively, the Japanese Orthopaedic Association (JOA) score of the 12 patients with cord symptoms had improved from 8.3 preoperatively to 13.9, with a mean improvement of 87.5%.

Conclusion:  Treatment of irreducible atlantoaxial dislocation with one‐stage anterior release and reduction with posterior fusion is a reliable method.
Laminoplasty for the treatment of extramedullary intradural tumors in the thoracic and lumbar spine: greater than two‐year follow‐up
Authors: Liu Xin‐yu , Zheng Yan‐ping , Li Jian‐min
Published: October 2009

Objective:  To investigate the outcome of a laminoplasty technique without additional instrumentation for fixation of laminae in the treatment of extramedullary intradural tumors in the thoracic and lumbar spine.

Methods:  Twenty‐four patients (15 men and 9 women) with extramedullary intradural tumors in the thoracic and lumbar spine were included in our study. The average age was 36.2 years (range 18 to 61 years). The pathological diagnosis was neurofibroma in 13, ependymoma in 6, lipoma in 2 and teratoma in 3 cases. All patients underwent the same laminoplasty surgery as follows: the laminae were reattached to their original sites, the ligaments (including the supraspinal, interspinal and yellow ligaments) were conserved, and primary stability of the re‐attached laminae was achieved with silk or nylon sutures.

Results:  Sixty‐six laminae were re‐implanted in 24 patients. The average length of follow‐up was 34.2 months (26.5 to 41 months). Fusion of the laminae was achieved in a mean of 4.5 months (3 to 6 months). Unilateral healing of the incision lines was observed in seven cases, including one with two‐level laminotomy, three with three‐level laminotomy and three with four‐level laminotomy. The other 17 cases underwent bilateral fusion.

Conclusion:  Fixing the laminae, spinous processes and ligaments with sutures can achieve satisfactory primary stability and high fusion rates for resected laminae. Additional instrumentation may be necessary in greater than three‐level laminoplasty.
Interbody cage support improves reconstruction of sagittal balance after anterior selective fusion in Lenke type 5 idiopathic scoliosis patients
Authors: Sun Xu , Qiu Yong , Liu Zhen , Ma Wei‐wei , Wang Bin , Zhu Ze‐zhang , Yu Yang , Qian Bang‐ping , Zhu Feng
Published: October 2009

Objective:  To investigate the effect of interbody cage support on reconstruction of the sagittal profile after anterior selective correction in Lenke type 5 adolescent idiopathic scoliosis (AIS) patients.

Methods:  In this retrospective study, a total of 40 AIS patients with a Lenke type 5 curve who underwent anterior selective fusion (ASF) using a single rod were studied. They were divided into two groups: Group A, bone grafting with an interbody titanium mesh cage (TMC); and Group B, bone grafting without a TMC. There were 19 female and 1 male patient aged 12–18 years in Group A, and 17 female and 3 male patients aged 13–20 years in Group B. All patients were followed up for more than 18 months. The coronal correction of the scoliosis and reconstruction of the sagittal profile were evaluated retrospectively.

Results:  By final follow‐up, more than 70% correction had been achieved for the primary curve and a spontaneous correction for the secondary curve in both groups. Satisfactory reconstructions on the sagittal plane were also observed. Similar changes were found in Group A and Group B, including increases in thoracic kyphosis, slight changes in thoracolumbar junctional kyphosis, no significant losses of lumbar lordosis, mild increases in proximal junctional measurement, and remarkable lordosis losses in the instrumented segments. With lessening of the sagittal balance and L1 offset, a significant anterior shift of the C7 plumb line was noted during follow‐up in Group A, indicating a more balanced spine in this group.

Conclusion:  Anterior selective single rod instrumentation and fusion is a recommended method for Lenke type 5C AIS. A structural interbody cage does not appear to improve the regional profile, nor the profiles in the instrumented area and the adjacent proximal and distal segments; yet could result in a better total balance in the long‐term.
Quantifying the Impact of Social Mobilisation in Rural Bangladesh: Donors, Civil Society and ‘The Road not Taken’
Authors: Kabeer Naila , Kabir Ariful Haq , Huq Tahera Yasmin
Published: October 2009

As part of a general trend toward a reduced role for the state, international donors have increasingly encouraged development NGOs to take up a service delivery function. In Bangladesh, this has induced NGOs to shift their core activities away from social mobilisation to a focus on providing microfinance services, although many organisations also promote education, health and other social services. NGOs are credited with some of Bangladesh's remarkable progress on poverty reduction, human development indicators and the Millennium Development Goals. However, social inequalities persist, and the quality of governance is extremely low. This paper reports on the impact of an NGO, Nijera Kori (NK), in rural Bangladesh on its members' democratic knowledge, practice and engagement. Unique among its peers, NK's work with the landless poor prioritises rights, social mobilisation and solidarity over more individualistic forms of democratic participation. The study carried out a survey of randomly selected members of NK, along with a randomly selected ‘control group’ from the same socioeconomic background of the NK membership. Statistical analysis of the data confirms much higher levels of political awareness and participation among NK members. More surprisingly, given that NK does not distribute microfinance, NK membership was also associated with a number of material impacts, including more diverse household diets, a higher likelihood of asset ownership and higher levels of economic activity relative to non‐members. Levels of ‘trust’ in local power structures and public institutions were significantly lower amongst NK members compared to non‐members, challenging some of the dominant assumptions about the positive correlation between social trust and political participation. We propose that NK's intensive focus on education, information‐sharing and social mobilisation instils a level of political consciousness in members that qualifies trust in public institutions, with implications for enhanced democratic accountability and an alternative civil society approach to improving democratic citizenship.
Who Are ‘Informal Health Providers’ and What Do They Do? Perspectives from Medical Anthropology
Authors: Cross Jamie , MacGregor Hayley
Published: October 2009

This paper explores gaps and limitations in the conceptualisation, methodology and policy implications of debates about informal health care providers by examining a cross section of empirical studies. Drawing on a tradition of critical medical anthropology, we argue that existing debates hinge on a particular understanding of what constitutes appropriate knowledge and on particular expectations of how economic actors in the medical marketplace will behave.
Target Reliability Levels for Design and Assessment of Onshore Natural Gas Pipelines
Authors: Nessim Maher , Zhou Wenxing , Zhou Joe , Rothwell Brian
Published: October 2009

This paper proposes a set of reliability targets that can be used in the design and assessment of onshore natural gas pipelines. The targets were developed as part of a PRCI-sponsored project that aims to establish reliability-based methods as a viable alternative for pipeline design and assessment. The proposed targets are calibrated to meet risk levels that are considered widely acceptable. The proposed criteria are based on a detailed consideration of both societal and individual risk criteria. Two societal risk criteria were considered: the first based on a fixed expectation of the number of fatalities and the second based on a risk aversion function as characterized by a F/N relationship. Societal risk criteria were calibrated to match or exceed the average safety levels implied by current codes. Individual risk criteria were based on published tolerable levels. The target reliability levels corresponding to the three criteria are presented and a recommended set of targets is presented.
Failure Analysis of a 9–12%Cr Steel Superheater Tube
Authors: Pour saeidi E. , Aieneravaie M. , Arhani M. R. Mohammadi
Published: October 2009

The failure analysis of 9–12% chromium steel tubes, containing about 2.5% molybdenum, is discussed in the present study. The component is used in a steam power plant boiler as a high-temperature superheater tube and has been in service for about 100,000 h. The failure occurred without appreciable wall thinning. Specimens were taken from the region beneath the fracture surface and investigated by optical and electron microscopes. The microstructure was composed of ferrite and grain boundary particulate carbides. The results indicated that the fracture was initiated because of the bending of the tube near the anchor and propagation of the crack through the interfaces between massive carbides and matrix (sensitized zone). Final fracture has occurred as a result of an overload due to the decreasing of load carrying section produced by crack propagation.
An Analytical Framework for the Solution of Autofrettaged Tubes Under Constant Axial Strain Condition
Authors: Hosseinian E. , Farrahi G. H. , Movahhedy M. R.
Published: October 2009

Autofrettage is a technique for introducing beneficial residual stresses into cylinders. Both analytical and numerical methods are used for the analysis of the autofrettage process. Analytical methods have been presented only for special cases of autofrettage. In this work, an analytical framework for the solution of autofrettaged tubes with constant axial strain conditions is developed. Material behavior is assumed to be incompressible, and two different quadratic polynomials are used for strain hardening in loading and unloading. Clearly, elastic perfectly plastic and linear hardening materials are the special cases of this general model. This quadratic material model is convenient for the description of the behavior of a class of pressure vessel steels such as A723. The Bauschinger effect is assumed fixed, and the total deformation theory based on the von Mises yield criterion is used. An explicit solution for the constant axial strain conditions and its special cases such as plane strain and closed-end conditions is obtained. For an open-end condition, for which the axial force is zero, the presented analytical method leads to a simple numerical solution. Finally, results of the new method are compared with those obtained from other analytical and numerical methods, and excellent agreement is observed. Since the presented method is a general analytical method, it could be used for validation of numerical solutions or analytical solutions for special loading cases.
Weight Minimization of Natural Gas Distribution Riser Systems
Authors: Attia M. S. , Megahed M. M. , Gaber A.
Published: October 2009

This study investigates the optimal piping layout in the installation of residential natural gas riser piping systems subjected to daily temperature fluctuations. Specifically, it is desired to evaluate the optimal safe configuration for minimum weight requirements in the absence of flexible expansion joints between the riser pipe and the branches. Structural optimization is carried out using fully parametric finite element models employing the singular value decomposition algorithm. Thermally induced stresses are examined to identify the optimal layout. The results indicate that the optimal piping layout satisfies strength requirements and achieves significant weight reduction and hence cost saving compared with existing, rule-based configurations.
A New Computational Method for Probabilistic Elastic-Plastic Fracture Analysis
Authors: Rahman Sharif
Published: October 2009

This paper presents a polynomial dimensional decomposition method for calculating the probability distributions of random crack-driving forces commonly encountered in elastic-plastic fracture analysis of ductile solids. The method involves a hierarchical decomposition of a multivariate function in terms of variables with increasing dimensions, a broad range of orthonormal polynomial bases consistent with the probability measure for Fourier-polynomial expansion of component functions, and an innovative dimension-reduction integration for calculating the expansion coefficients. Unlike the previous development, the new decomposition does not require sample points, yet it generates a convergent sequence of lower-variate estimates of the probability distributions of crack-driving forces. Numerical results, including the probability of fracture initiation of a through-walled-cracked pipe, indicate that the decomposition method developed provides accurate, convergent, and computationally efficient estimates of the probabilistic characteristics of the J-integral.
Spatially Resolved Materials Property Data From a Uniaxial Cross-Weld Tensile Test
Authors: Turski M. , Smith M. C. , Bouchard P. J. , Edwards L. , Withers P. J.
Published: October 2009

Application of electronic speckle pattern interferometry (ESPI) is described to measure the spatial variation in monotonic tensile stress-strain properties along “cross-weld” specimens machined from a stainless steel three-pass welded plate. The technique, which could also be done with digital image correlation, was applied to quantify how the material 0.2%, 1%, 2%, 5%, 10%, and 20% proof stress varied with distance from the center-line of the weldment for parent and weld material associated with the first and final passes. The stress-strain curves measured by the ESPI method correlated closely with stress-strain data measured using conventional test specimens. The measured results are consistent with the hypothesis that thermo-mechanical cycles associated with the welding process work harden previously deposited (single-pass) weld metal and the surrounding parent material. The stress-strain response of the heat affected zone adjacent to the first weld pass is consistent with an accumulated (equivalent monotonic) plastic strain of 6.5% and that of the first pass weld bead was consistent with an accumulated plastic strain of approximately 4% greater than the state of the final pass weld metal.
A Model for Predicting Temperature of Electrofusion Joints for Polyethylene Pipes
Authors: Shi Jianfeng , Zheng Jinyang , Guo Weican , Xu Ping , Qin Yongquan , Zuo Shangzhi
Published: October 2009

With the increasing application of electrofusion (EF) welding in connecting polyethylene (PE) pipes for gas distribution, more effort has been invested to ensure the safety of the pipeline systems. The objective of this paper is to investigate and understand the temperature distribution during EF welding. A one-dimensional transient heat-transfer model was proposed, taking the variation in the rate of power input, the phase transition of PE, and the thermal contact conductance between heating wire and PE into consideration. Then, experiments were designed to verify the power input and the temperature. The measured values of the power input were shown to be in good agreement with the analytical results. Based on ultrasonic test (UT), a new “Eigen-line” method was presented, which overcomes the difficulties found in the thermocouples’ temperature measurements. The results demonstrate good agreements between prediction and experiment. Finally, based on the presented model, a detailed parametric study was carried out to investigate the influences of the variation in the power input, the physical properties of PE, and the thermal contact conductance between heating wire and surrounding PE.
Dynamic Burst Pressure Simulation of Cylindrical Shells
Authors: Cheng Cunjiang , Widera G. E. O.
Published: October 2009

The object of this study is to determine the short-term burst pressure of metal cylinders under short-term dynamic loading conditions. The finite element method via the use of the LS-DYNA code (1998, LS-DYNA Theoretical Manual, Livermore Software Technology Corporation) is used to carry out the study. The influence of the geometric parameters diameter (D) and wall thickness (T) as well as loading parameters such as the dynamic pressure versus time function is examined. Additionally, an empirical formula based on experimental data and incorporating the ultimate dynamic strength of low carbon steel is developed. Based on the agreement between the results of the finite element analyses and those of the empirical formula, it can be concluded that a properly modeled finite element analysis (FEA) can be employed with sufficient accuracy to study the short-term dynamic burst pressures of metal cylinders.
Nonlinear Buckling and Postbuckling Behavior of 3D Braided Composite Cylindrical Shells Under External Pressure Loads in Thermal Environments
Authors: Li Zhi-Min , Lin Zhong-Qin , Chen Guan-Long
Published: October 2009

Nonlinear buckling and postbuckling behavior for a 3D braided composite cylindrical shell of finite length subjected to lateral pressure, hydrostatic pressure, or external liquid pressure in thermal environments have been presented in this paper. Based on a new micromacromechanical model, a 3D braided composite may be treated as a cell system and the geometry of each cell is deeply dependent on its position in the cross section of the cylindrical shell. The material properties of the epoxy are expressed as a linear function of temperature. The governing equations are based on Reddy’s higher order shear deformation shell theory with a von Kármán–Donnell type of kinematic nonlinearity and including thermal effects. A singular perturbation technique is employed to determine the buckling pressure and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling behavior of perfect and imperfect braided composite cylindrical shells with different values of geometric parameter and of fiber volume fraction in different cases of thermal environmental conditions. The results show that the shell has lower buckling pressures and postbuckling paths when the temperature-dependent properties are taken into account. The results reveal that the temperature changes, the fiber volume fraction, and the shell geometric parameter have a significant effect on the buckling pressure and postbuckling behavior of braided composite cylindrical shells.
Structure and properties of ZrN doped diamondlike carbon films prepared by pulsed bias arc ion plating
Authors: Li H. K. , Lin G. Q. , Dong C.
Published: October 2009

ZrN doped diamondlike carbon composite films with different compositions were deposited on cemented carbide substrates at different nitrogen flow rates by pulsed bias arc ion plating. Scanning electron microscopy results show that the film surfaces were all uniform, smooth, and dense. X-ray photoelectron spectroscopy reveal the C contents are more than 60%, the N content increases, and the Zr content decreases with increasing nitrogen flow rate. The Raman spectra indicated that the deposited films were diamondlike carbon. X-ray diffraction results suggested that a ZrN crystalline phase was also present in the films. The hardness and elastic modulus were closely related to the composition and structure of the films and decrease with increasing nitrogen flow rates, principally due to the increase in the sp2 content and the decrease in the ZrN crystalline phase.
Analysis of carbon in SrTiO3 grown by hybrid molecular beam epitaxy
Authors: Jalan Bharat , Cagnon Joël , Mates Thomas E. , Stemmer Susanne
Published: October 2009

Secondary ion mass spectroscopy (SIMS) was used to investigate carbon impurity concentrations in stoichiometric SrTiO3 films grown by a hybrid molecular beam epitaxy approach that uses an effusion cell to supply strontium, a rf plasma source for oxygen and a metal organic titanium source (titanium tetra isopropoxide). The carbon concentration in the films was measured as a function of growth parameters. At sufficiently high growth temperatures (>800 °C), the films contain a few ppm of carbon. The challenges in accurately quantifying low carbon concentrations are discussed. A carbon-containing contamination layer is detected on the surfaces of SrTiO3 substrates and air-exposed films by SIMS and in scanning transmission electron microscopy. The contamination layer could be removed by high-temperature predeposition oxygen plasma cleaning.
Lung Myeloid Dendritic Cells Coordinately Induce T
H
1 and T
H
17 Responses in Human Emphysema
Authors: Shan Ming , Cheng Han-Fang , Song Li-zhen , Roberts Luz , Green Linda , Hacken-Bitar Joan , Huh Joseph , Bakaeen Faisal , Coxson Harvey O. , Storness-Bliss Claudine , Ramchandani Mahesh , Lee Seung-Hyo , Corry David B. , Kheradmand Farrah
Published: October 2009

Specialized immune cells in the lungs of patients with emphysema create an inflammatory environment that drives lung destruction in a characteristic autoimmune reaction.
A Radical Proposal: Integrate Clinical Investigation into the U.S. Health Care System
Authors: Rudick Richard A. , Cosgrove Delos M.
Published: October 2009

Integration of the clinical research enterprise into the U.S. health care system would ultimately improve public health.
A Breath of Fresh Air for Lung Transplant Recipients
Authors: Wilkes David S.
Published: October 2009

Lung transplantation is a definitive therapy for the treatment of many
end-stage lung diseases. However, because of donor-related morbidities,
only 15% of donor lungs are suitable for transplantation, which leads to
an increased risk of death for prospective patients waiting for this
lifesaving procedure. A technique reported by Keshavjee’s group
in this issue of
Science Translational Medicine
may
help address this problem, not only by repairing donor lungs before
transplant, but also by possibly preventing lung injury after
transplantation.
High frequency of fumigants and other toxic gases in imported freight containers—an underestimated occupational and community health risk
Authors: Baur Xaver , Poschadel Bernd , Budnik Lygia Therese
Published: October 2009

Residues of pesticide fumigants and toxic industrial chemicals in freight containers represent a health hazard to employees and consumers, especially since freight containers are sealed for transport and distributed widely throughout the importing countries before being opened for unloading.

We investigated 2113 freight containers arriving at the second largest container terminal in Europe, Hamburg, Germany, over a 10-week period in 2006. The countries of origin, type of contents and the pesticide fumigation history declared on labels attached to the container were recorded.

We determined that 1478 (70%) containers were contaminated with toxic chemicals above chronic reference exposure levels; 761 (36%) even exceeded the higher acute reference exposure level thresholds. Benzene and/or formaldehyde contamination was 4-times greater than for fumigants.

Our findings indicate a health risk for dockworkers, container unloaders and even end-consumers, especially as many of the cancerogenic or toxic gases elude subjective detection.
Increased risk of oesophageal adenocarcinoma among upstream petroleum workers
Authors: Kirkeleit Jorunn , Riise Trond , Bjørge Tone , Moen Bente E , Bråtveit Magne , Christiani David C
Published: October 2009

Objectives

To investigate cancer risk, particularly oesophageal cancer, among male upstream petroleum workers offshore potentially exposed to various carcinogenic agents.

Methods

Using the Norwegian Registry of Employers and Employees, 24 765 male offshore workers registered from 1981 to 2003 was compared with 283 002 male referents from the general working population matched by age and community of residence. The historical cohort was linked to the Cancer Registry of Norway and the Norwegian Cause of Death Registry.

Results

Male offshore workers had excess risk of oesophageal cancer (RR 2.6, 95% CI 1.4 to 4.8) compared with the reference population. Only the adenocarcinoma type had a significantly increased risk (RR 2.7, 95% CI 1.0 to 7.0), mainly because of an increased risk among upstream operators (RR 4.3, 95% CI 1.3 to 14.5). Upstream operators did not have significant excess of respiratory system or colon cancer or mortality from any other lifestyle-related diseases investigated.

Conclusion

We found a fourfold excess risk of oesophageal adenocarcinoma among male workers assumed to have had the most extensive contact with crude oil. Due to the small number of cases, and a lack of detailed data on occupational exposure and lifestyle factors associated with oesophageal adenocarcinoma, the results must be interpreted with caution. Nevertheless, given the low risk of lifestyle-related cancers and causes of death in this working group, the results add to the observations in other low-powered studies on oesophageal cancer, further suggesting that factors related to the petroleum stream or carcinogenic agents used in the production process might be associated with risk of oesophageal adenocarcinoma.
Experimental reintroduction of the crayfish species Orconectes virilis into formerly acidified Lake 302S (Experimental Lakes Area, Canada)This paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Phillips Iain D. , Vinebrooke Rolf D. , Turner Michael A.
Published: October 2009

Reintroduction of functionally important species is considered a key strategy for restoring damaged ecosystems. However, the sudden reappearance of an extirpated species may have adverse ecological impacts, degrading ecosystem services. Therefore, we experimentally reintroduced the crayfish Orconectes virilis into a biologically recovering, formerly acidified Boreal Shield lake (Lake 302S, Experimental Lakes Area, Canada) to determine its effect on the littoral food web following a 17-year absence. In June 2004, a single-factor experimental design consisting of two treatment levels (crayfish-less control versus 1.8 introduced crayfish·m–2) was replicated five times for a total of 10 littoral cages (4 m2). Orconectes virilis significantly (P < 0.05) suppressed the total biomass of other benthic invertebrates by 70% primarily because of declines in larval damselflies and midges. In addition, crayfish reduced periphytic biomass by 90% (P < 0.001). Stable isotopic analyses of the mesocosm food webs further indicated that O. virilis likely functioned as an omnivore, exerting direct and possibly indirect effects on other invertebrates and periphyton. Our findings highlight how the reintroduction of O. virilis must be balanced with adequate fish predation to prevent this species from becoming an invader and negatively affecting the productive capacity of boreal lakes.
Ecosystem-level regulation of boreal lake phytoplankton by ultraviolet radiationThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Xenopoulos Marguerite A. , Leavitt Peter R. , Schindler David W.
Published: October 2009

Unique and interactive effects of ultraviolet radiation (UVR), temperature, and water column mixing on phytoplankton abundance and community composition were quantified using regression and multivariate analysis for lakes of differing transparencies and UVR exposure regimes located at the Experimental Lakes Area in Canada. Abundance of planktonic diatoms and chrysophytes (as fucoxanthin) and total algae (as chlorophylls) were negatively correlated with UVB exposure (R2= 0.57 and R2= 0.64, respectively) in slightly stained lakes. In contrast, concentrations of both filamentous Cyanobacteria and dinoflagellates were positively correlated with UVB levels in eutrophic and humic lakes (dissolved organic carbon >9 mg·L–1) (R2= 0.23 and R2= 0.27), whereas all algal groups were uncorrelated with UVB in oligotrophic ecosystems. Although univariate analyses suggested that surface water temperature explained more variation in algal abundance than UVB, principal components analyses revealed that the two factors often covaried and could not be statistically disentangled. Instead, it appears that strong UVB effects on lake algal communities occur commonly when optical and thermal properties interact to maximize exposure to high irradiances. Unexpectedly, UVR could either suppress or stimulate surface algal growth depending on the precise combination of lake parameters and algal community composition.
A stressor-independent test for biodiversity – ecosystem function relationships during a 23-year whole-lake experimentThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Vinebrooke Rolf D. , Turner Michael A. , Findlay David L. , Paterson Michael J.
Published: October 2009

Anthropogenic stressors are the current drivers of loss of global biodiversity and deterioration of ecosystem function (e.g., primary production). However, it is debatable whether human stressors or associated changes in biodiversity better predict the impairment of ecosystem function. Variation in plankton communities during a whole-lake experiment (Lake 302S, Experimental Lakes Area, Canada) was examined to test whether the stressor treatment effect or subsequent stressor-independent variation in species richness best explained interannual variation in aggregate functional properties, such as productivity or net total biomass. Although significant “biodiversity – ecosystem function” relationships were detected, these correlations were confounded by the negative effect of experimental acidification on species richness. The stressor effect was removed by plotting functional properties against the residuals from the species richness – pH regressions, which generated either negative or nonsignificant relationships. The lack of significant stressor-independent positive relationships between functional properties and species richness highlights the potential greater importance of other mediating factors, such as interactions among multiple stressors, species identity, and altered trophic interactions, at the whole-ecosystem scale.
Benthic algal biomass — measurement and errorsThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Baulch Helen M. , Turner Michael A. , Findlay David L. , Vinebrooke Rolf D. , Donahue William F.
Published: October 2009

While benthic algal biomass is one of the most commonly measured variables within littoral communities, it is also one of the most poorly characterized. The use of chlorophyll a as an estimate of biomass, while easy and inexpensive, can be affected by changes in environmental conditions and algal community composition. Biovolume-based measurements often have high variability and are affected by changes in cell volume due to preservation. Using 12 years of data from the Experimental Lakes Area (northwestern Ontario, Canada) as well as short-term surveys and experimental studies from the Experimental Lakes Area and the Canadian Rocky Mountains, we demonstrate that biovolume and chlorophyll a are often decoupled in the littoral zone of temperate oligotrophic lakes. We recommend that researchers revisit the limitations of both metrics and specifically caution against the use of chlorophyll a as a biomass indicator when light, temperature, or species composition vary significantly.
Separating the effects on water chemistry of climate variation and experimental manipulation in the long-term acidification and recovery of lakesThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Hesslein Raymond H. , Turner Michael A. , Guss Douglas , Lyng Mark
Published: October 2009

Changes in climate, in particular significant changes in precipitation and evaporation and thus runoff, as well as changes in regional atmospheric deposition can affect the changes in chemical masses or concentrations in lakes. We have examined the changes in alkalinity, sulfate, and dissolved organic carbon (DOC) during a 20-year period when Lake 302S and Lake 302N at the Experimental Lakes Area (Ontario, Canada) were acidified with sulfuric, nitric, and hydrochloric acids and returned to natural pH. We used the corresponding 20-year history in Lake 239 to build chemical mass balance models for the experimental lakes. With these models, we assessed the production of alkalinity and the loss of sulfate and DOC in the context of atmospheric and watershed inputs and our experimental acid additions. Alkalinity production was greatest during the period of highest acid inputs and not detectable during pH recovery even in the early stages when pH was still low. Sulfate loss was also greatest while sulfate concentrations were increasing but counter to expectations not directly related to sulfate concentrations. Losses of the mass of DOC showed little change in response to acid additions over the 20 years, but first-order losses increased at low pH.
Survival and behaviour of rainbow trout (Oncorhynchus mykiss) released from an experimental aquaculture operationThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Blanchfield Paul J. , Tate Lori S. , Podemski Cheryl L.
Published: October 2009

The potential for farmed fish that have escaped from open-cage aquaculture operations to affect native populations will depend on their survival and behaviour in the wild. We used standard commercial practices to rear 10 tonnes of rainbow trout ( Oncorhynchus mykiss ) in a 23 ha lake at the Experimental Lakes Area (Ontario, Canada). Each fall (2003–2005), we released farmed rainbow trout (escapees) into the study lake and monitored their movements using automated positioning telemetry. Rainbow trout experienced high annual mortality (~50%), with none surviving beyond 3 years. Farmed fish had narrowly defined pelagic distributions that comprised the upper few metres of the water column, even when at the cage site. Although released rainbow trout dispersed throughout the study lake, most spent significant portions of time at the cage site, especially during normal operation when commercial feed was available. Core use areas (50% Kernel) included the farm for half of the released fish. Surviving rainbow trout showed continued reliance upon the cage site in their second year. However, wide dispersal, high growth rate, and lack of reliance on the cage site by some escaped fish warrant further research to assess potential effects of open-cage aquaculture in the water bodies where the industry occurs.
Effects of an experimental rainbow trout (Oncorhynchus mykiss) farm on invertebrate community compositionThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Rooney Rebecca C. , Podemski Cheryl L.
Published: October 2009

We examined the development of changes in the zoobenthos along a transect from an experimental rainbow trout ( Oncorhynchus mykiss ) farm in Lake 375, Experimental Lakes Area, northwestern Ontario, Canada. After 2 months, invertebrate abundance was reduced under the fish cage (2542 ± 569 individuals·m–2) compared with samples collected 45 m away (16 137 ± 2624 individuals·m–2). Taxa richness was also depressed, but changes in biomass were variable. Reductions in abundance and richness at high organic loading levels are consistent with earlier models developed for the marine environment of responses to organic loading in marine systems. After two production cycles, the significant principal components axis explaining 76% of total variance in abundance was correlated with distance from the cage (Spearman rank correlation, r = –0.775, p = 0.014) and with chemical variables recommended for freshwater aquaculture monitoring (Pearson’s correlation coefficient, r = 0.78, 0.76, and 0.75 with p = 0.013, 0.018, and 0.020 for pore-water ammonia and sediment Cu and Zn, respectively). The effects of farming were localized, dissipating within 15 m of the cage edge. Invertebrate abundance demonstrated the most potential for incorporation into monitoring schemes at new farms. At established farms, richness may be a valuable monitoring metric.
A personal history of the Experimental Lakes ProjectThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Schindler D. W.
Published: October 2009

I briefly trace the evolution of the Experimental Lakes Area project from its beginning as a temporary site sponsored by the now-defunct Fisheries Research Board of Canada, with the sole mandate to investigate the effects of nutrients on lake eutrophication, to its current status: a permanent field station cosponsored by the Canadian Departments of Environment and Fisheries and Oceans, with a mandate to investigate the aquatic effects of a wide variety of stresses on lakes and their catchments. Throughout, experiments have been designed to address important aquatic management issues, but this mandate has not hindered the production of pure research on a broad variety of issues.
Johnson and Vallentyne’s legacy: 40 years of aquatic research at the Experimental Lakes Area
Authors: Blanchfield Paul J. , Paterson Michael J. , Shearer John A. , Schindler David W.
Published: October 2009

Wally Johnson and Jack Vallentyne played key roles in the establishment of the Experimental Lakes Area (ELA), which comprises a research team, a set of protected lakes, and a field station, with the mandate to quantify anthropogenic impacts to lakes through whole-ecosystem manipulation and monitoring. We begin this collection of papers, celebrating four decades of aquatic research at the ELA, by reflecting on the historical relevance and scientific milestones of the ELA. The remaining papers encompass themes at the core of ELA research: long-term ecological monitoring of unimpacted reference lakes, ecosystem responses to anthropogenic stressors through whole-system experimentation, recovery of manipulated ecosystems from perturbation, and detailed mechanistic studies. Utilizing these approaches, papers in this issue examine a wide variety of anthropogenic impacts on freshwater including the ecosystem effects of climate change, recovery from lake acidification, upland and wetland flooding on methyl mercury levels in biota, endocrine-disrupting chemicals on fish populations, and freshwater aquaculture. These studies emphasize the value of long-term monitoring and experimentation at the ecosystem scale for understanding human impacts on freshwaters.
Long-term changes in climate, streamflow, and nutrient budgets for first-order catchments at the Experimental Lakes Area (Ontario, Canada)This paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.
Authors: Parker Brian R. , Schindler David W. , Beaty Ken G. , Stainton Michael P. , Kasian Susan E.M.
Published: October 2009

We analyzed 36 years of records for climate, hydrology, and the chemistry of precipitation and runoff from the Lake 239 (Rawson Lake) catchment at the Experimental Lakes Area (Ontario, Canada). No evidence of significant periodicity was found for any variable in the Experimental Lakes Area records. The longer (67-year) record from nearby Kenora, Ontario, revealed a 31-year cycle in precipitation but not temperature. Significant increasing long-term trends at the Experimental Lakes Area were found for annual and winter temperature and summer precipitation and deposition of ammonium, total nitrogen (TN), and total dissolved nitrogen (TDN). Large (80%) increases in ammonium deposition appear to be related to higher emissions in the central United States. A significant negative trend for dissolved organic carbon (DOC) in precipitation cannot be explained. In runoff, significant positive trends were found for TDN and DOC in the northeast catchment and TN, TDN, ammonium, and DOC in the northwest. Significant negative trends were found for TDP and nitrate in the northeast. Significant increases were found for retention of ammonium in all catchments and DOC in the northeast and northwest. There was no apparent relationship between forest succession and retention of nutrients. Results are compared with those from three other long-term monitoring sites in eastern North America.
Copolymerization of sterically demanding phosphine-olefins and 1-hexene
Authors: McCahill Jenny S.J. , Stephan Douglas W.
Published: October 2009

The copolymerization of 1-hexene with t-Bu2P(CH2)3CH=CH2 (1) or t-Bu2P(CH2)9CH=CH2 (2) has been achieved using CpMe2Ti(NPt-Bu3) as the precatalyst and B(C6F5)3, [Ph3C][B(C6F5)4], or [PhNMe2H][B(C6F5)4] as the activator. The resulting polymers are shown to incorporate up to 9% of the phosphine comonomer, albeit with reduced catalyst activity and polymer molecular mass. The cause of the catalyst inhibition is also considered in the light of phosphine–activator interactions.
Energy additivity in branched and cyclic hydrocarbons
Authors: Gao Hongwei , Bader Richard F. W. , Cortés-Guzmán Fernando
Published: October 2009

This paper considers the degree to which branched hydrocarbons obey a group additivity scheme for energy and population, extending the study of the known experimental and theoretical transferability of the methyl and methylene groups of the linear hydrocarbons. The chemical groups are defined and their properties are determined using the quantum theory of atoms in molecules (QTAIM). The calculations are carried out with a large basis set at the restricted Hartree–Fock and MP2(full) levels of theory. The deviations from additivity, noted for small ring hydrocarbons leading to the definition of strain energy, are also investigated, showing that the QTAIM energies recover the experimental values. The particular delocalization of the electron density over the surface of the cyclopropane ring, responsible for its “homoaromatic” properties, is discussed in some detail. The calculations reported here satisfy the virial theorem as required for the atomic definition of energy. The problems associated with the use of DFT theory arising from its failure to satisfy the virial theorem are discussed with reference to the study of group transferability.