bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Testing and Strength Prediction of Ceramic-to-Metal Joints
Authors: Selverian J. H. , O’Neil D. A. , Kang S.
Published: April 2008

Brazed joints were made between silicon nitride and Ni-based and Fe-based super alloys. Room temperature shear (torsion) strengths ranged from 75-242 MPa for Si3N4-to-Incoloy 909 joints and from 30-127 MPa for the Si3N4-to-Inconel 718 joints. At 500°C the joint strength was 120 MPa while at 650°C and 950°C the joint strengths were less than 20 MPa. These low strengths at 650°C and 950°C were attributed to a reduction in the shrink-fit and to low braze strength at these high temperatures. Finite element analysis (FEA) and a probabilistic failure theory (CARES) were used to predict the joint strengths. The predicted joint strengths agreed well with measured joint strengths in torsional loading at 20°C. Torsion tests were also performed at 650°C. Aspects of the material systems, residual stresses, mechanical behavior, and strength predictions and presented. Two new braze alloys based on the Au-Ni-Cr-Fe system were used to overcome the poor high-temperature strength. Joints made with these brazes had good strength (85 MPa and 35 N-m) at 650°C.
Microstructural Investigation of the Weld HAZ in a Modified 800H Alloy
Authors: Lundin C. D. , Qiao C.-Y. P.
Published: April 2008

Detailed metallographic investigations of Gleeble simulated HAZ samples in modified 800H were performed. Precipitate dissolution, gain growth, HAZ liquation and the hardness degradation behavior in modified 800H were also addressed. Results of this study agree with previous HAZ hot cracking and softening behavior evaluations.
Calibrating Ultrasonic Images for the NDE of Structural Materials
Authors: Gilmore R. S. , Glaeser A. M. , Wade J. C.
Published: April 2008

Ultrasonic imaging is taking a larger and larger role in the NDE of turbine engine materials and in support of fracture mechanics calculations. It is also playing an increasing role in quality and process control. For most fracture toughness calculations, it is necessary to establish the accuracy with which a flaw’s size and shape are imaged, whether single or multiple flaws are involved, and the spacing of multiple flaws. Because of these requirements, resolution, as well as detection sensitivity, has become an issue. There are a number of resolution targets that can provide this type of calibration information for an ultrasonic imaging system. A fused quartz USAF 1951 target, similar to the patterns used in this work, was first used by Gilmore (1986), but Gilmore’s pattern was superficial and subsurface evaluations were limited to focusing on the pattern from the opposite side of the blank and monitoring the reflection from what is now the target backwall. Work by Paton (1977) did produce buried targets in titanium samples, but there was no practical method to produce buried targets in high-temperature ceramics until the techniques developed by Rodel and Glaeser (1987) were used to produce the targets described in this paper. Optically transparent resolution targets make it feasible to verify visually that the resolution target has been correctly fabricated. An image of the target with a candidate ultrasonic transducer then permits quantitative image resolution estimates to be made even when the interrogating acoustic beam contains significant refractive aberration. This is important because useful subsurface images can be acquired with the use of acoustic beams that are aberrant to the point that diffraction-limited beam-width calculations are meaningless. This work also demonstrates how the interdisciplinary skills of manufacturing companies can be combined with those of universities to produce results that any one of the individual members of the team could not have produced alone, without significant increases in labor, time, and cost.
Design and Experimental Characterization of a Nonintrusive Measurement System of Rotating Blade Vibration
Authors: Nava P. , Paone N. , Rossi G. L. , Tomasini E. P.
Published: April 2008

A measurement system for nonintrusive monitoring of rotating blade vibration in turbomachines based on fiber optic sensors is presented. The design of the whole system is discussed; the development of special purpose sensors, their interfacing to the data acquisition system, and the signal processing are outlined. The processing algorithms are tested by software simulation for several possible blade vibrations. Experimental tests performed on different bladed rotors are presented. Results are compared to simultaneous strain gage measurements.
Three-Dimensional Vibration Analysis of Rotating Laminated Composite Blades
Authors: McGee O. G. , Chu H. R.
Published: April 2008

This work offers the first known three-dimensional continuum vibration analysis for rotating, laminated composite blades. A cornerstone of this work is that the dynamic energies of the rotating blade are derived from a three-dimensional elasticity-based, truncated quadrangular pyramid model incorporating laminated orthotropicity, full geometric nonlinearity using an updated Lagrangian formulation and Coriolis acceleration terms. These analysis sophistications are included to accommodate the nonclassical directions of modern blade designs comprising thin, wide chord-lifting surfaces of laminated composite construction. The Ritz method is used to minimize the dynamic energies with displacements approximated by mathematically complete polynomials satisfying the vanishing displacement conditions at the blade root section exactly. Several tables and graphs are presented that describe numerical convergence studies showing the validity of the assumed displacement polynomials used herein. Nondimensional frequency data are presented for various rotating, truncated quadrangular pyramids, serving as first approximations of practical blades employed in aircraft engines and fans. A wide scope of results explain the influence of a number of parameters coined to rotating, laminated composite blade dynamics, namely aspect ratio (a/b), chord ratio (c/b), thickness ratio (b/h), variable thickness distribution (h1/ht), blade pretwist angle (φ0), composite fiber orientation angle (θ), and angular velocity (Ω). Additional examples are given that elucidate the significance of the linear and nonlinear kinematics used in the present three-dimensional formulation along with the importance of the Coriolis acceleration terms included in the analysis.
Experimental Study on Vibration of a Rotating Blade
Authors: Fan Y. C. , Ju M. S. , Tsuei Y. G.
Published: April 2008

The vibration of a rotating blade is investigated in this work. A rotor system is built and natural frequencies of the rotating blade are measured and compared with the numerical results from a finite element analysis. The experimental setup has a strain-gage-based telemetry system and a piezoelectric shaker that rotates with the rotor. The finite element model of the beam is derived based on the Timoshenko beam theory. The effects of varying rotating speeds and stagger angles on the blade natural frequencies are studied. The results indicate that the natural frequencies calculated from the finite element model and the experimental values are in good agreement. It is found that the blade natural frequencies increase with the rotating speed in a nonlinear way. The effects of the stagger angle on the measured natural frequencies are not clear.
Dynamic Analysis of Squeeze Film Damper Supported Rotors Using Equivalent Linearization
Authors: El-Shafei A. , Eranki R. V.
Published: April 2008

The technique of equivalent linearization is presented in this paper as a powerful technique to perform nonlinear dynamic analysis of squeeze film damper (SFD) supported rotors using linear rotor-dynamic methods. Historically, it is customary to design SFDs for rotor-dynamic analysis by assuming circular-centered orbits, which is convenient in making the nonlinear damper coefficients time independent and thus can be used in an iterative approach to determine the rotor-dynamic characteristics. However, the general synchronous orbit is elliptic in nature due to possible asymmetry in the rotor support. This renders the nonlinear damper coefficients time dependent, which would require extensive numerical computation using numerical integration to determine the rotor dynamic characteristics. Alternatively, it is shown that the equivalent linearization, which is based on a least-squares approach, can be used to obtain time-independent damper coefficients for SFDs executing eccentric elliptic orbits, which are nonlinear in the orbit parameters. The resulting equivalent linear forces are then used in an iterative procedure to obtain the unbalance response of a rigid rotor-SFD system. Huge savings over numerical integration are reported for this simple rotor. The technique can be extended to be used in conjunction with currently available linear rotor-dynamic programs to determine the rotor-dynamic characteristics through iteration. It is expected that for multirotor multibearing systems this technique will result in even more economical computation.
Chaotic Behavior of Rotor/Stator Systems With Rubs
Authors: Goldman P. , Muszynska A.
Published: April 2008

This paper outlines the dynamic behavior of externally excited rotor/stator systems with occasional, partial rubbing conditions. The observed phenomena have one major source of a strong nonlinearity: transition from no contact to contact state between mechanical elements, one of which is rotating, resulting in variable stiffness and damping, impacting, and intermittent involvement of friction. A new model for such a transition (impact) is developed. In case of the contact between rotating and stationary elements, it correlates the local radial and tangential (“super ball”) effects with global behavior of the system. The results of numerical simulations of a simple rotor/stator system based on that model are presented in the form of bifurcation diagrams, rotor lateral vibration time-base waves, and orbits. The vibrational behavior of the system considered is characterized by orderly harmonic and subharmonic responses, as well as by chaotic vibrations. A new result is obtained in case of heavy rub of an anisotropically supported rotor. The system exhibits an additional subharmonic regime of vibration due to the stiffness asymmetry. The correspondence between numerical simulation of that effect and previously obtained experimental data supports the adequacy of the new model of impact.
1993 Soichiro Honda Lecture: The Challenges of Change in the Auto Industry: Why Alternative Fuels?
Authors: Nichols R. J.
Published: April 2008

Development of vehicles to operate on nonpetroleum fuels began in earnest in response to the energy shocks of the 1970s. While petroleum will remain the predominant transportation fuel for a long time, petroleum supplies are finite, so it is not too soon to begin the difficult transition to new sources of energy. In the past decade, composition of the fuel utilized in the internal combustion engine has gained recognition as a major factor in the control of emissions from the tailpipe of the automobile and the rate of formation of ozone in the atmosphere. Improvements in air quality can be realized by using vechicles that operate on natural gas, propane, methanol, ethanol, or electricity, but introduction of these alternative fuel vehicles presents major technical and economic challenges to the auto industry, as well as the entire country, as long as gasoline remains plentiful and inexpensive.
Concepts for the Adaptation of SI Gas Engines to Changing Methane Number
Authors: Schiffgens H.-J. , Endres H. , Wackertapp H. , Schrey E.
Published: April 2008

In a joint project of FEV Motorentechnik and Ruhrgas AG, the design of stoichiometric and lean-burn Otto engines was optimized by selective modifications to the design and operating parameters to accommodate changing methane numbers (LPG addition to CNG). Of particular importance was knock-free engine operation at a low NOx output to meet the requirements of the German Clean Air Code while concurrently achieving both high efficiencies and mean effective pressures. Based upon the results obtained, concepts for the control of Otto-cycle gas engines to accept changing methane numbers were developed. The newly developed gas engine control device allows these concepts to meet the requirement of the German Clean Air Code with economically viable conditions while preventing engine knock. Furthermore, the test results show that dedicated Otto-cycle gas engines can meet the most stringent emission limits for commercial vehicles while maintaining high efficiencies.
Coal-Fueled Diesel Development: A Technical Review
Authors: Ryan T. W.
Published: April 2008

The purpose of this paper is to describe and summarize the results of the Coal Fueled Diesel Engine Development Program, sponsored by the U.S. Department of Energy, Morgantown Energy Technology Center. The results of the program indicate that diesel engines can be designed to operate reliably on coal–water slurries. The engine must be modified to include hard-wear resistant rings and liners. The injection system design must be modified to accommodate the slurry and to incorporate hard materials for wear prevention.
The General Electric Coal-Fueled Diesel Engine Program (1982–1993): A Technical Review
Authors: Caton J. A. , Hsu B. D.
Published: April 2008

In the early 1980s, General Electric—Transportation Systems (GE-TS), a manufacturer of locomotive diesel engines, announced plans to develop a coal-fueled locomotive due to the availability and low cost of coal. In 1985 and 1988, the General Electric Company (GE) was awarded major contracts from the Department of Energy, Morgantown Energy Technology Center, to continue the research and development of a coal-fueled diesel engine. This paper is a review of the technical accomplishments and discoveries of the GE coal-fueled diesel engine research and development program during the years 1982–1993. The results of an economic assessment completed by GE-TS indicated the merits for the development of a coal fueled diesel engine for locomotive applications and therefore, GE-TS embarked on an ambitious program to develop and commercialize a coal-fueled diesel engine. Among the major accomplishments of this program were the development of specialized fuel injection equipment for coal–water slurries, diamond compact inserts for the nozzle tips for wear resistance, and an integrated emissions control system. Over 500 hours of engine operation was accumulated using coal fuel during the duration of this program. A major milestone was attained when, during November and December 1991, a coal-fueled diesel engine powered a locomotive on the General Electric test track.
Development and Test of a Fractional Sampling System for Diesel Engine Particulate Measurement
Authors: Graze R. R.
Published: April 2008

Diesel engine particulate certification, heretofore limited to on-highway truck engines, will be expanded in scope beginning in 1996. “Mini-dilution” tunnels have been the European and Japanese systems of choice for dilute particulate emissions certification for non-U.S. truck diesel engines. However, repeatability, steady-state test correlation versus full dilution systems, portability, sampling time, size, and system cost have precluded universal industry and regulatory acceptance of existing “mini-system” designs. To address corporate particulate measurement needs, the author developed a device known internally as the “Micro-Dilution Particulate Measurement System,” which meets the following objectives: (1) correlation with full dilution systems within ISO 8178 equivalency standards, (2) short sampling time, (3) reduced setup effort, and (4) excellent portability. Since the system is a true fractional sampler, it is insensitive to engine size, requiring only a simple stack probe change to provide accurate, representative steady-state diesel stack sampling on any size diesel engine.
Exhaust Emissions From Two Intercity Passenger Locomotives
Authors: Fritz S. G.
Published: April 2008

To enhance the effectiveness of intercity passenger rail service in mitigating exhaust emissions in California, the California Department to Transportation (Caltrans) included limits on exhaust emissions in its intercity locomotive procurement specifications. Because there were no available exhaust emission test data on which emission reduction goals could be based, Caltrans funded a test program to acquire gaseous and particulate exhaust emissions data, along with smoke opacity data, from two state-of-the-art intercity passenger locomotives. The two passenger locomotives (an EMD F59PH and a GE DASH8-32BWH) were tested at the Association of American Railroads Chicago Technical Center. The EMD locomotive was eqiupped with a separate Detroit Diesel, Corporation (DDC) 8V-149 diesel engine used to provide 480 V AC power for the trailing passenger cars. This DDC engine was also emission tested. These data were used to quantify baseline exhaust emission levels as a challenge to locomotive manufacturers to offer new locomotives with reduced emissions. Data from the two locomotive engines were recorded at standard fuel injection timing and with the fuel injection timing retarded 4 deg in an effort to reduce NOx emissions. Results of this emissions testing were incorporated into the Caltrans locomotive procurement process by including emission performance requirements in the Caltrans intercity passenger locomotive specification, and therefore in the procurement decision. This paper contains steady-state exhaust emission test results for hydrocarbons (HC), carbon monoxide (CO), oxides of nitrogen (NOx), and particulate matter (PM) from the two locomotives. Computed sulfur dixoide (SO2) emissions are also given, and are based on diesel fuel consumption and sulfur content. Exhaust smoke opacity is also reported.
Effect of Ring Dynamics and Crevice Flows on Unburned Hydrocarbon Emissions
Authors: Shih L. K. , Assanis D. N.
Published: April 2008

A significant source of unburned hydrocarbon emissions from internal combustion engines originates from the flow of unburned fuel/air mixture into and out of crevices in the piston-cylinder-ring assembly. During compression, fuel vapor flows into crevice regions. After top dead center, the trapped fuel vapor that returns into the cylinder escapes complete oxidation and contributes to unburned hydrocarbon emissions. In this work, the crevice flow model developed by Namazian and Heywood is implemented into KIVA-II, a multidimensional, reacting flow code. Two-dimensional, axisymmetric simulations are then performed for a 2.5 liter gasoline engine to investigate the effects of engine speed and selected piston-ring design parameters on crevice flows and on unburned hydrocarbon emissions. Results suggest that engine-out unburned hydrocarbon emissions can be reduced by optimizing the ring end gap area and the piston-cylinder side clearance.
Torch Ignition: Ideal for Lean Burn Premixed-Charge Engines
Authors: Mavinahally N. S. , Assanis D. N. , Govinda Mallan K. R. , Gopalakrishnan K. V.
Published: April 2008

Sluggish flame initiation and propagation, and even potential misfiring, become major problems with lean-fueled, premixed-charge, spark-ignited engines. This work studies torch ignition as a means for improving combustion, fuel economy, and emissions of a retrofitted, large combustion chamber with nonideal spark plug location. A number of alternative configurations, employing different torch chamber designs, spark-plug locations, and materials, were tested under full-load and part-load conditions. Results indicate a considerable extension of the lean operating limit of the engine, especially under part-load conditions. In addition, torch ignition can lead to substantial thermal efficiency gains for either leaner or richer air-fuel ratios than the optimum for the conventional ignition system. On the richer side, in particular, the torch-ignited engine is capable of operating at maximum brake torque spark timings, rather than compromised, knock-limited spark timings used with conventional ignition. This translates into thermal efficiency improvements as high as 8 percent at an air-fuel ratio of 20:1 and full load.
A Rayleigh-Type Inclusion of Shaft Inertia in Torsional Vibration Analysis
Authors: Doughty S.
Published: April 2008

This paper considers the problem of properly accounting for the shafting inertia in torsional vibration analysis. It begins with a brief review of the two well-established methods: (1) arbitrarily lumping the shaft inertia with that of the disks, and (2) the continuum model, which considers both the flexibility and the inertia as distributed properties. Comments regarding the advantages and disadvantages of each are offered as motivation for the new method to be presented here. The new approach is then developed, using a Rayleigh-type approximation for the displacement between stations, with the full theory underlying it. The results of all three methods are then compared by application to several test cases.
Sign Change of Poisson's Ratio for Carbon Nanotube Sheets
Authors: Hall Lee J. , Coluci Vitor R. , Galvão Douglas S. , Kozlov Mikhail E. , Zhang Mei , Dantas Sócrates O. , Baughman Ray H.
Published: April 2008

Most materials shrink laterally like a rubber band when stretched, so their Poisson's ratios are positive. Likewise, most materials contract in all directions when hydrostatically compressed and decrease density when stretched, so they have positive linear compressibilities. We found that the in-plane Poisson's ratio of carbon nanotube sheets (buckypaper) can be tuned from positive to negative by mixing single-walled and multiwalled nanotubes. Density-normalized sheet toughness, strength, and modulus were substantially increased by this mixing. A simple model predicts the sign and magnitude of Poisson's ratio for buckypaper from the relative ease of nanofiber bending and stretch, and explains why the Poisson's ratios of ordinary writing paper are positive and much larger. Theory also explains why the negative in-plane Poisson's ratio is associated with a large positive Poisson's ratio for the sheet thickness, and predicts that hydrostatic compression can produce biaxial sheet expansion. This tunability of Poisson's ratio can be exploited in the design of sheet-derived composites, artificial muscles, gaskets, and chemical and mechanical sensors.
Plastin 3 Is a Protective Modifier of Autosomal Recessive Spinal Muscular Atrophy
Authors: Oprea Gabriela E. , Kröber Sandra , McWhorter Michelle L. , Rossoll Wilfried , Müller Stefan , Krawczak Michael , Bassell Gary J. , Beattie Christine E. , Wirth Brunhilde
Published: April 2008

Homozygous deletion of the survival motor neuron 1 gene (
SMN1
) causes spinal muscular atrophy (SMA), the most frequent genetic cause of early childhood lethality. In rare instances, however, individuals are asymptomatic despite carrying the same
SMN1
mutations as their affected siblings, thereby suggesting the influence of modifier genes. We discovered that unaffected
SMN1
-deleted females exhibit significantly higher expression of plastin 3 (
PLS3
) than their SMA-affected counterparts. We demonstrated that PLS3 is important for axonogenesis through increasing the F-actin level. Overexpression of PLS3 rescued the axon length and outgrowth defects associated with SMN down-regulation in motor neurons of SMA mouse embryos and in zebrafish. Our study suggests that defects in axonogenesis are the major cause of SMA, thereby opening new therapeutic options for SMA and similar neuromuscular diseases.
Coordination of Early Protective Immunity to Viral Infection by Regulatory T Cells
Authors: Lund Jennifer M. , Hsing Lianne , Pham Thuy T. , Rudensky Alexander Y.
Published: April 2008

Suppression of immune responses by regulatory T cells (Tregs) is thought to limit late stages of pathogen-specific immunity as a means of minimizing associated tissue damage. We examined a role for Tregs during mucosal herpes simplex virus infection in mice, and observed an accelerated fatal infection with increased viral loads in the mucosa and central nervous system after ablation of Tregs. Although augmented interferon production was detected in the draining lymph nodes (dLNs) in Treg-deprived mice, it was profoundly reduced at the infection site. This was associated with a delay in the arrival of natural killer cells, dendritic cells, and T cells to the site of infection and a sharp increase in proinflammatory chemokine levels in the dLNs. Our results suggest that Tregs facilitate early protective responses to local viral infection by allowing a timely entry of immune cells into infected tissue.
Genome-Scale Proteomics Reveals
Arabidopsis thaliana
Gene Models and Proteome Dynamics
Authors: Baerenfaller Katja , Grossmann Jonas , Grobei Monica A. , Hull Roger , Hirsch-Hoffmann Matthias , Yalovsky Shaul , Zimmermann Philip , Grossniklaus Ueli , Gruissem Wilhelm , Baginsky Sacha
Published: April 2008

We have assembled a proteome map for
Arabidopsis thaliana
from high-density, organ-specific proteome catalogs that we generated for different organs, developmental stages, and undifferentiated cultured cells. We matched 86,456 unique peptides to 13,029 proteins and provide expression evidence for 57 gene models that are not represented in the TAIR7 protein database. Analysis of the proteome identified organ-specific biomarkers and allowed us to compile an organ-specific set of proteotypic peptides for 4105 proteins to facilitate targeted quantitative proteomics surveys. Quantitative information for the identified proteins was used to establish correlations between transcript and protein accumulation in different plant organs. The
Arabidopsis
proteome map provides information about genome activity and proteome assembly and is available as a resource for plant systems biology.
Fluids of Hard Nonspherical Molecules. II. Monte Carlo Data and Equation of State
Authors: Morávek Pavel , Kolafa Jiří , Francová Magda
Published: April 2008

New accurate data on the compressibility factor of the hard homonuclear diatomics with a full range of elongations and the hard prolate spherocylinders with length-to-width ratio as high as 9 are presented. The data were obtained by Monte Carlo NpT simulations with finite-size corrections in the range of reduced pressures βp* = 0.5-7.0. New equations of state based on simultaneous correlation of the data with the virial coefficients up to the ninth are presented.
Sitosterolaemia: pathophysiology, clinical presentation and laboratory diagnosis
Authors: Kidambi S , Patel S B
Published: April 2008

Sitosterolaemia is an extremely rare autosomal recessive disease, the key feature of which is the impairment of pathways that normally prevent absorption and retention of non-cholesterol sterols, for example plant sterols and shellfish sterols. The clinical manifestations are akin to familial hypercholesterolaemia (such as presence of tendon xanthomas and premature atherosclerosis), but with “normal to moderately elevated” cholesterol levels. The gene(s) causing sitosterolaemia was mapped to the STSL locus on human chromosome 2p21, and mutations in either of the two genes that comprise this locus, ABCG5 or ABCG8, cause this disease. Exact prevalence is unknown, but there are estimated to be 80–100 cases around the world. This rare disease has shed light into the molecular mechanisms that control sterol trafficking in the enterocyte and hepatocyte; ABCG5 and ABCG8 heterodimerise to form a sterol efflux transporter in the liver and intestine. In this review the pathophysiology, clinical manifestations and approach to clinical and laboratory diagnosis of this disease are described.
Relationship of the absolute difference between direct and indirect ion selective electrode measurement of serum sodium and the total protein concentration
Authors: Jones B J , Twomey P J
Published: April 2008

Aim:

To derive the relationship for the difference between direct and indirect ion selective electrode measurements of serum sodium and the total protein concentration.

Methods:

Using modern analysers and independent specimens that covered the whole of the total protein range, linear relationships were derived for the difference between direct and indirect ion selective electrode measurements of serum sodium and the total protein concentration.

Results:

The regression data were as follows: absolute difference = 0.1196 TP – 5.9528, r2 = 0.4555, p<10−48; relative difference = 0.0849 TP – 4.1199, r2 = 0.4153, p<10−43.

Conclusions:

A linear regression equation for the relationship of the absolute difference between direct and indirect ion selective electrode measurements of serum sodium and the total protein concentration can be validly derived. However, due to the large spread of data around the regression line, such equations should not be employed to decide when to use direct electrodes instead of indirect electrodes in routine clinical laboratories.
Mucinous, gland predominant synovial sarcoma of a large peripheral nerve: a rare case closely mimicking metastatic mucinous carcinoma
Authors: Weinreb I , Perez-Ordoñez B , Guha A , Kiehl T-R
Published: April 2008

Synovial sarcoma is a distinctive soft tissue neoplasm with monophasic and biphasic forms. It is typically a deep-seated soft tissue tumour of the extremities of young adults and occasional cases have been described in large peripheral nerves. A rare example has a predominance of the glandular component and may mimic metastatic carcinoma. Here, a unique synovial sarcoma with <1% spindle cell component involving the posterior tibial nerve is decribed. In addition to having only small bands or islands of stroma, there was also mucin dissection of the surrounding soft tissue. Isolated glands were seen “floating” in pools of mucin. There was abundant intracellular mucin present as well. These latter two findings have not been described in synovial sarcoma thus far, to our knowledge. The diagnosis was confirmed by molecular detection of the t(X;18) by reverse transcription-PCR and confirmed by dual colour break apart fluorescence in situ hybridisation, in a second laboratory. Mucinous, gland predominant synovial sarcoma must be recognised to avoid misdiagnosis of metastatic carcinoma or a glandular malignant peripheral nerve sheath tumour when occurring in a peripheral nerve.
Polycythaemia rubra vera and myelofibrosis with spinal cord compression
Authors: Scott I C , Poynton C H
Published: April 2008

Spinal cord compression from extramedullary haemopoiesis within the spinal epidural space is a rare complication of myelofibrosis and polycythaemia rubra vera (PRV). A 69-year-old male with PRV (later transforming to myelofibrosis) who developed this complication is described here. Due to the uncertainty over its optimal treatment, previous case reports were systematically reviewed to define its presentations, treatments and outcomes. Including the present case this complication has been reported in 21 patients with myelofibrosis and PRV: 17 were male and the mean symptom duration was 7.6 months. Neurological improvement occurred in 14 patients and 12 survived. Seventy-five per cent of patients receiving combined treatment (irradiation with laminectomy or chemotherapy) showed neurological improvement and 100% survived. In contrast, 67% of those receiving single treatments exhibited improved neurology and only 33% survived. It is concluded that spinal cord compression in myelofibrosis and PRV has a high mortality, with combined treatment providing a better prognosis.
Signet ring cells of stromal derivation in the uterine cervix secondary to cauterisation: report of a previously undescribed phenomenon
Authors: McKenna M , McCluggage W G
Published: April 2008

Aims:

To describe the occurrence of signet ring cells of stromal origin within the uterine cervix.

Methods:

Following the identification of prominent signet ring cells in the stroma in a large loop excision of transformation zone (LLETZ) biopsy of cervix (the index case), a series of LLETZ specimens was prospectively examined for this phenomenon.

Results:

Focal collections of identical signet ring cells in 15% of the specimens were found. The cells were characterised by bland eccentric round or crescentic nuclei with a single cytoplasmic vacuole. The signet ring cells in the index case were vimentin positive, and negative with cytokeratins, epithelial membrane antigen and CD68, in keeping with a stromal derivation.

Conclusions:

In all cases, the signet ring cells were in areas of thermal damage and they are believed to be an artefact of cauterisation; identical features have been described in transurethral resection of prostate specimens and also attributed to thermal damage. When the change is extensive in the cervix, there is potential for misdiagnosis as a signet ring carcinoma. Other cervical lesions with signet ring cells are discussed.
Recent Growth, Biochemical Composition and Prey Field of Larval Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) on Georges Bank
Authors: Buckley L. J. , Lough R. G.
Published: April 2008

A transect across southern Georges Bank in May 1983 showed higher levels of available prey for haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) larvae at two stratified sites than at a well-mixed site. At the stratified sites, prey biomass was high (30–300 μg dry wt∙L−1) near the surface above the thermocline; values were lower and more uniform with depth (10–30 μg dry wt∙L−1) at the well-mixed site. Larval population centers generally coincided with prey biomass vertically. Recent growth in dry weight of haddock larvae as estimated by RNA–DNA ratio analysis was higher at the stratified sites (8–13%∙d−1) than at the well-mixed site (7%∙d−1). Larvae appeared to be in excellent condition at the stratified sites, but up to 50% of haddock larvae from the well-mixed site had RNA–DNA ratios in the range observed for starved larvae in the laboratory. Cod collected at the same site were in better condition and growing faster than haddock. The data support the hypotheses that (1) stratified conditions in the spring favor good growth and survival of haddock larvae and (2) cod larvae are better adapted to grow and survive in well-mixed waters at lower levels of available food than haddock larvae.
Recruitment to Northwest Atlantic Cod (Gadus morhua) and Haddock (Melanogrammus aeglefinus) Stocks: Influence of Stock Size and Climate
Authors: Koslow J. Anthony , Thompson Keith R. , Silvert William
Published: April 2008

Year-class success of both Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) stocks in the northwest Atlantic exhibits large-scale coherence and low-frequency variability with apparent periodicities of 10–20 yr. Several physical and biological variables in the region exhibit similar large-scale coherence and apparent periodicity. Multiple regression analysis indicates that year-class success in northwest Atlantic cod stocks tends to be associated with large-scale meteorological patterns and offshore winds. Recruitment to most haddock stocks from the Scotian Shelf to Georges Bank is negatively associated with abundance of 0-group mackerel, which may be due to predation over winter and/or to a combination of environmental features including sea-surface temperature, large-scale atmospheric pressure systems, and freshwater outflows. Statistical analyses often did not define a unique set of variables that best predicted fishery recruitment due to widespread intercorrelations among environmental processes and the likelihood that not all relevant processes entered directly into the analyses. There is little evidence that stock reproductive output during the study period was significantly related to year-class success.
Evaluation of in situ Enclosures for Larval Fish Studies
Authors: Lafontaine Yves de , Leggett William C.
Published: April 2008

Two in situ enclosure designs intended for use in larval fish studies were evaluated for their capability to reproduce and track the physical properties of the surrounding water and to maintain the behavioral characteristics of enclosed organisms. The enclosures, which were constructed of porous material, allowed near instantaneous response to natural variations in temperature, salinity, and dissolved oxygen at all depths. Phytoplankton biomass inside the enclosures was less variable than that observed outside and its size composition was related to the porosity of the material used. Particle sinking rates inside the enclosures were much lower than those previously reported for plastic bags, suggesting a higher degree of turbulence in our enclosures. Newly hatched larval capelin (Mallotus villosus) and Zooplankton stocked into the enclosures exhibited diel migration of amplitude similar to that observed in the field. Zooplankton were more homogeneously distributed than fish larvae although heterogeneity decreased at night for both taxa. Low cost, ease of handling, environmental reproducibility, and quality of replication provided by the enclosures make them particularly appropriate for replicated experimental studies of the interactions between larval fishes, their predators, and prey.
Development and Performance of an Alaska Steeppass Fishway for Sockeye Salmon (Oncorhynchus nerka)
Authors: Blackett Roger F.
Published: April 2008

A major introduced run of sockeye salmon (Oncorhynchus nerka) at Frazer Lake, Kodiak Island, Alaska, is perpetuated by an Alaska steeppass fishway at a 10-m-high falls on the outlet river. Experimental modifications of the fishway, which was inadequate by 1970 as the salmon run increased, improved salmon entry and passage. Sockeye passage over 4 yr was nearly equivalent in a steeppass of 60 m continuous length (22% slope) and an adjoining steeppass with three resting pools, but significant year-to-year differences in passage occurred between steeppasses. Resting tanks were beneficial for holding slower or descending salmon without blocking passage of other salmon. An average entry of 142 sockeye in 15 min was achieved by guiding all salmon along a weir to an entrance tank with a vertical slot orifice. Chutes installed in the entry end of the steeppasses created a high-velocity stream for attraction and decreased salmon dropout from the entrance tank. Salmon passage in the original steeppasses with three resting pools was greater than in new (1979) steeppasses with a single resting pool. In 1985, sockeye passage of 2925/h and 46 806/d exceeded fishway capacity requirements.
Food Quality and Hydropsychid Caddisfly Density in a Lake Outlet Stream in Glacier National Park, Montana, USA
Authors: Valett H. M. , Stanford J. A.
Published: April 2008

Hydropsychid caddisfly larval density averaged 6500/m2in the lake outlet, but decreased to 1427 and 209/m2at a distance of 200 and 3400 m downstream. Food quantity, measured as the concentration of particulate organic carbon in grab samples of seston, differed significantly between sites on only 3 of 13 sampling dates. But food quality variables (i.e. protein and ATP content of seston) were significantly higher in the lake outlet during months of higher lake productivity; monthly values of particulate protein regressed negatively with distance downstream. We concluded that stable substrate, discharge, and temperature regimes, combined with a plentiful supply of high-quality food, maintained high densities of filter-feeding hydropsychids in the lake outlet. Downstream populations were limited by comparatively greater abiotic variation (i.e. discharge, substratum, diel temperature) and by a concomitant decrease in seston food quality.
Acclimation to Copper by Rainbow Trout,Salmo gairdneri: Physiology
Authors: Laurén Darrel Jon , McDonald D. G.
Published: April 2008

Juvenile rainbow trout (Salmo gairdneri) were exposed to 55 μg copper∙L−1for 28 d and then transferred to uncontaminated water for 7 d. Whole body sodium concentration and sodium uptake (Jin) were measured at weekly intervals; Jinwas measured at various Na+concentrations and kinetic parameters estimated. After 24 h of copper exposure, the maximum rate of sodium uptake (Jmax) was inhibited by 55%, the affinity for sodium (Km) reduced by 49%, and whole body Na+decreased by about 12.5%. After 7 d of exposure, whole body Na+had returned to control values, but Jmaxwas still inhibited by 41%. Recovery of whole body Na+occurred largely by a reduction of sodium efflux (Jout). Both Jmaxand Kmcontinued to recover until day 28, at which time Jinhad returned to control values. We conclude that acclimation to sublethal copper depends on changes in both Na+transport and permeability.
Selection of Microhabitat in Summer by Juvenile Atlantic Salmon (Salmo salar)
Authors: Morantz D. L. , Sweeney R. K. , Shirvell C. S. , Longard D. A.
Published: April 2008

This study was designed to define the microhabitats selected in summer by juvenile Atlantic salmon (Salmo salar). Curves were developed describing the preference of 880 young salmon for water velocity at the fish's position (nose velocity), mean water column velocity, total water depth, and stream substrate size. Study sites were chosen in six morphologically diverse streams in Nova Scotia and New Brunswick during 1982–84. Of the four variables measured, only nose velocity chosen by both fry and parr was not significantly different among years or rivers. Atlantic salmon fry (< 65 mm) most frequently selected nose velocities between 5 and 15 cm∙s−1, small parr (65–100 mm) between 5 and 25 cm∙s−1 and large parr (> 100 mm) between 5 and 35 cm∙s−1. Apparently, juvenile salmon utilized water depths and stream substrates which varied within tolerable limits according to their availability in conjunction with preferred water velocities. Significant differences in the body shape and size of the pectoral fin of Atlantic salmon parr in different rivers did not influence the selection of nose velocities within the range of flow conditions sampled.
Effects of Coal Leachates on Fish Spermatogenesis
Authors: Cochran Roger C.
Published: April 2008

Coal leachates were examined for toxic effects on fish spermatogenesis. Nonbreeding mummichogs, Fundulus heteroclitus, were induced to enter breeding condition in the laboratory by exposure to 20 °C and a photoperiod of 16L: 8D for 6 wk. During this 6-wk period, mummichogs were dosed in static exposure tanks with water extracts of coal (leachates). Chi-square analysis and Z test of proportions revealed a significant reduction in sperm production by fish exposed to some, but not all, coal leachates. This reduction was as much as 40-fold and occurred in a dose-dependent manner. Ordinarily, nonbreeding mummichogs collected immediately after the breeding season will not enter breeding condition in response to 16L: 8D and 20 °C. Exposure of these photo-insensitive mummichogs to coal leachates under long photoperiod conditions for 8 wk resulted in a significant increase in sperm production. Analysis of weekly sperm production by mummichogs from six field populations, either adjacent to or 2 miles upstream from coal-fired power plants, did not reveal significant differences during the breeding season. However, this sperm production was less than 1/10 that of a mummichog field population sampled concomitantly at the Chesapeake Bay Institute. The reduced sperm levels could not be related to reproductive toxin(s) contained in coal leachate.
Regulation of Tin and Methyltin Compounds by the Green Alga Enteromorpha under Simulated Estuarine Conditions
Authors: Donard Olivier F. X. , Short Fredrick T. , Weber James H.
Published: April 2008

The cycling of inorganic tin and methyltin compounds was examined in the presence of the green alga Enteromorpha at different salinities. We monitored flasks containing live and dead Enteromorpha under oxic experimental conditions for 17 d and determined inorganic tin and methyltin compounds by chromatography – atomic absorption spectrometry. Addition of acidic inorganic tin to some flasks resulted in plant decay. Processes associated with healthy and decaying plant material included release of inorganic tin and methyltin compounds, their interconversions in solution, and uptake of inorganic tin. Enteromorpha releases inorganic tin as well as mono-, di-, and trimethyltin. Added inorganic tin was mostly removed from solution after its addition, and all three methyltin compounds were produced. The methyltin compounds cycle such that high concentrations of trimethyltin were concomitant with low mono- and dimethyltin concentrations and vice versa. We describe possible biological and chemical processes responsible for interconversions of inorganic tin and methyltin compounds in solution and the environmental significance of seaweed in the biogeochemical cycling of tin.
Structure and Function of Phytoplanktonic and Microbial Communities in Relation to Industrial Wastewater Discharge: An Ecotoxicological Approach in a Lotic System
Authors: Couture Pierre , Thellen Claude , Thompson Patsy A. , Auclair Jean-Christian
Published: April 2008

Microbial and phytoplanktonic processes of a perturbed river system were evaluated as an ecotoxicological alternative to bioassays in hazard assessment of industrial wastewater discharge. Although phytoplankton species composition was invariable throughout the river gradient, both P/B and ATP/AMP ratios revealed that the community did not acclimate over the spatial scale studied. The adenylate energy charge (ECA) of the microbial community decreased at the station where the wastewater is discharged; however, no significant differences in (ECA) values were observed downstream. Enclosure experiments allowed us to conclude that the microbial community was predominantly affected by the effluent rather than by the lotic physical gradient. In the river gradient, ECAappears to be an insensitive metabolic indicator; however, small changes in ECAare accompanied by much larger changes in the ATP/AMP ratios to which enzymatic activities are responding. The fact that some functional metabolic processes of the microbial community were affected while phytoplankton species composition was invariable suggests that P/B and ATP/AMP ratios would prove useful in the detection of insidiuous effects of industrial effluents at the microbial community level. This approach could also give more insight into the ecological significance of wastewater discharge for monitoring purposes.
Small-Scale Variability of New Production and Particulate Fluxes in the Ocean
Authors: Vézina Alain F. , Platt Trevor
Published: April 2008

Particulate carbon losses from the surface waters of the ocean can be estimated from short-term ([Formula: see text]) determinations of the contribution of nitrate to total nitrogen uptake (f(t)), under the assumption that the nitrate flux represents the supply of N from external sources. We used numerical modeling of the euphotic food web to explore the relationship between short-term variability in f(t) and the long-term export normalized to production, [Formula: see text]. We found that modeling sedimentation as a nonlinear process was necessary to simulate variability in f(t). The resulting model generated nonlinear relationships of f(t) to Pt and f(t) to [NO3] that, to date, have only been empirically described. The shape of the f ratio curves depends on an exponent n that expresses a power law dependence of the sedimentation rate on the concentration of suspended material in the euphotic zone, for which there is increasing empirical support. Simulations of the model with a temporally variable NO3 supply show that particulate losses can amount to 30–40% of production in seasonal oligotrophic systems. The model suggests that [Formula: see text] in N-limited ocean provinces depends on the variance of the nutrient field and on the sensitivity of the loss rate to variations in the plankton biomass in the euphotic zone.