bluuebunny/crossref_metadata_2025 huggingface dataset:
Dating of Dissolved Iodine in Pore Waters from the Gas Hydrate Occurrence Offshore Shimokita Peninsula, Japan: 129I Results from the D/V Chikyu Shakedown Cruise
Authors: Tomaru Hitoshi , Fehn Udo , Lu Zunli , Takeuchi Rika , Inagaki Fumio , Imachi Hiroyuki , Kotani Ryosuke , Matsumoto Ryo , Aoike Kan
Published: November 2009

Iodine concentration and radioisotopic composition (129I/I) were measured in the pore waters from the gas hydrate occurrence in the forearc basin offshore Shimokita Peninsula, north‐eastern Japan, to determine the source formation of I and accompanying hydrocarbons. Iodine concentrations correlate well with the alkalinity and SO4 patterns, reflecting degradation stages of I‐rich buried organic matter, rapidly increasing in the sulfate reduction interval, and becoming constant below 250 meters below the seafloor with an upwelling flux of 1.5 × 10−11 µmol cm−2 year−1. The 129I/I ratios of 300 × 10−15–400 × 10−15 in deep pore waters suggest ages for iodine and hydrocarbon sources as old as 40 Ma. These ages correlate well with the coaly source formations of the Eocene age thought to be responsible for the conventional natural gas deposits underlying the gas hydrate stability zone. Similar profiles are observed in 129I/I ratios of pore waters in the gas hydrate stability zone from the forearc basin in the eastern Nankai Trough, offshore central Japan, where pore waters are enriched in I and reach ages as old as ∼50 Ma through the sediment column. At the outer ridge site along the trough, on the other hand, relatively younger I are more frequently delivered probably through thrusts/faults associated with subduction. The nature of source formations of I and hydrocarbons in the offshore Shimokita Peninsula has a more terrestrial contribution compared with those in the Nankai Trough, but these formations are also considerably older than the host sediments, suggesting long‐term transport of I and hydrocarbons for the accumulation of gas hydrates in both locations.
State‐dependent life history models in a changing (and regulated) environment: steelhead in the California Central Valley
Authors: Satterthwaite William. H. , Beakes Michael P. , Collins Erin M. , Swank David R. , Merz Joseph E. , Titus Robert G. , Sogard Susan M. , Mangel Marc
Published: November 2009

We use a state dependent life history model to predict the life history strategies of female steelhead trout (Oncorhynchus mykiss) in altered environments. As a case study of a broadly applicable approach, we applied this model to the American and Mokelumne Rivers in central California, where steelhead are listed as threatened. Both rivers have been drastically altered, with highly regulated flows and translocations that may have diluted local adaptation. Nevertheless, evolutionary optimization models could successfully predict the life history displayed by fish on the American River (all anadromous, with young smolts) and on the Mokelumne River (a mix of anadromy and residency). The similar fitness of the two strategies for the Mokelumne suggested that a mixed strategy could be favored in a variable environment. We advance the management utility of this framework by explicitly modeling growth as a function of environmental conditions and using sensitivity analyses to predict likely evolutionary endpoints under changed environments. We conclude that the greatest management concern with respect to preserving anadromy is reduced survival of emigrating smolts, although large changes in freshwater survival or growth rates are potentially also important. We also demonstrate the importance of considering asymptotic size along with maximum growth rate.
Externally Pressurized Gas Journal Bearings With Porous Inserts
Authors: Majumdar B. C.
Published: November 2009

An analytical solution of externally pressurized gas journal bearings with porous inserts as restrictors is presented. The solution is based on a first-order perturbation method with respect to eccentricity ratio.
Investigations of Externally Pressurized Gas Bearings With Different Feeding Systems
Authors: Kazimierski Z. , Trojnarski J.
Published: November 2009

A general calculation method for gas journal bearings with pocketed or annular orifices feeding systems is presented. The accuracy of the method is demonstrated by comparison with a large number of experimental results. Good agreement between the theoretical and experimental results led to the application of the calculation method to the examination of some bearing properties which depend on the feeding system geometry. Examinations of the influence of the type of feeding holes and of their dimensions on the load coefficient and on the power consumption per unit load were performed. The results are of significance to the practical application of gas lubricated bearings.
A Generalized Short Bearing Theory
Authors: Rohde S. M. , Li D. F.
Published: November 2009

This paper discusses new approximate solutions to Reynolds equation. A generalized short bearing approximation is developed which is applicable to a large class of hydrodynamic bearings. Several examples are presented and comparisons between approximate results and the exact solutions for finite bearings are made.
Behavior of Finite Journal Bearings Under Dynamic Loading Conditions
Authors: Shawki G. S. A. , Mokhtar M. O. A. , Safar Z. S.
Published: November 2009

Performance characteristics for a complete journal bearing of finite axial length are obtained analytically using a new set of boundary conditions. The generalized Reynolds equation is transformed, in the present analysis, into three ordinary differential equations, two of which being readily integrable while the third is solved by variational methods. By the aid of a specially devised computer program, the validity of the analysis has been assured when applied to prescribed journal loci including stationary, circular, elliptical, and linear harmonic journal oscillation.
Observations and Analysis of Mechanical Seal Film Characteristics
Authors: Nau B. S.
Published: November 2009

The history of mechanical seal interface studies is summarized and the underlying unity of different approaches is presented diagrammatically. The distinction between “cavitation” and “vapor-transition” is discussed and photographs of seal films are presented to demonstrate similarities. An analytical approach to the calculation of film cavitation boundaries is presented together with a total flow conservation numerical technique. Results from each are presented and it is concluded that cavitation extent will often be greater than expected using over-simplified treatments.
Micropolarity—Roughness Interaction in Hydrodynamic Lubrication
Authors: Prakash J. , To̸nder K. , Christensen H.
Published: November 2009

The paper describes a theoretical analysis of micropolarity-roughness interaction. A modified Reynolds’ type equation for a rough surface based on micropolar fluid theory is developed and is applied to the case of a fixed inclined slider, having a one-dimensional roughness pattern in the direction transverse to sliding. The analysis shows that the inclusion of surface roughness in the theory causes an increase in the pressure level, over and above the micropolar level. However, these additional increases are of a smaller order and are not likely to mask the increases caused by additives and surface forces (characterized by micropolarity) as is conjectured by some earlier workers.
Surface Roughness Effects on the Load Carrying Capacity of Very Thin Compressible Lubricating Films
Authors: White J. W.
Published: November 2009

The effect of surface roughness on load carrying capacity of very low clearance gas bearings is analyzed. A model lubrication equation appropriate for high bearing number, finite width films is first derived. Then, by obtaining exact solutions to several simple geometry bearings, the “closure problem” or statistical relationship of pressure and spacing is revealed. The lubrication equation is then ensamble averaged and solved for several test cases. The seemingly subtle differences in ensamble averaging the transverse terms in the lubrication equation are compared for the current theory and a previous method and are shown to produce vast differences in load carrying capacity. The current method is expected to be the correct approach since it is based on a generalization of exact solutions.
Formation and Separation of Thin Viscous Film in Hertzian Line Contacts
Authors: Dalmaz Ge´rard
Published: November 2009

The conditions of film formation and of film separation are examined experimentally and theoretically in a line Hertzian contact when the inlet region is partially filled with oil, in steady state hydrodynamic regime, for both rolling and sliding conditions. It is shown experimentally that the importance of the parameter μU/T (viscosity and speed/surface tension) differs at inlet and exit. At contact exit the influence of μU/T is dominant and the film divides to form a meniscus which can be stable or unstable. The validity of the Coyne and Elrod model is confirmed. At contact inlet when reverse flow disappears, a meniscus is also formed with a downstream circulation zone. The instability of the exit air-oil meniscus is studied theoretically using the linearized perturbation method with the thin film assumptions. A simple and complete analytical solution yields both a stability criterion and the wave number for the linear contact geometry. These results which are compared with experiments for thin film and for 0.01 < μU/T < 1 show the validity of the stability criterion and that best agreement is obtained with the wave number of maximum amplification.
Surface Topography Changes in Polymer-Metal Sliding - I
Authors: Jain V. K. , Bahadur S.
Published: November 2009

The adhesive wear of polymers, sliding against smooth metal surfaces, is influenced by the manner in which the surface topography of sliding surfaces is modified. The variation in the surface topographical parameters with sliding between a ground steel disc and a poly(methyl methacrylate) pin was, therefore, investigated for both the unsteady state and steady state wear conditions. The surface profiles of the unrubbed and rubbed metal disc were recorded, using a profilometer, both along and perpendicular to the direction of sliding. From the profile ordinate data read at 10 μm intervals, the surface roughness parameters, namely, the rms and c.l.a. roughness, asperity radius of curvature, asperity density, and average asperity slope were calculated using a computer program. Three point analysis was used to define a peak and compute the asperity slope and radius of curvature. The distributions of surface parameters were determined using a Weibull distribution approach. The analysis showed that the surface parameters have a large initial variation followed by more or less stable conditions, which explains the transition of unsteady state wear to steady state wear. The changes on the disc surface perpendicular to the sliding direction are minimal. The rms roughness and the average asperity slope were found to have a linear relationship.
Oxidative Wear in Lubricated Contact
Authors: Newley R. A. , Spikes H. A. , Macpherson P. B.
Published: November 2009

Lubricant antioxidant additives are known to reduce fretting wear. Wear tests have been carried out in association with chemical analyses of the test lubricant to elucidate the mechanism of oxidative wear. It is shown that the rate of wear is not directly related to the concentration in the lubricant of either acids or peroxides. It is proposed that the metal is oxidized by reacting with peroxy radicals which form as intermediates as the lubricant is oxidized. The reduction of wear in the presence of antioxidants is a result of the elimination of these radicals by the additive.
Hardness Controlled Thermal Failures
Authors: Rozeanu L. , Pnueli D.
Published: November 2009

Heating, wear, and failure are feared effects of friction. The relationship between them is analyzed in terms of slide/roll ratio, relative velocity variation, and relative hardness relations. It is shown that the effect of intersecting hardness curves is the same as that of deceleration, and can cause thermal failure by the same mechanism. The failure is related to the transient departure from steady state according to particular correspondence between the thermal and mechanical variables. Experimental evidence is provided in support of the theoretical argumentation.
Interactive Computing in the Application of Monotonicity Analysis to Design Optimization
Authors: Zhou J. , Mayne R. W.
Published: November 2009

The use of monotonicity analysis in design optimization has been demonstrated in a number of publications in recent years. The purpose of this paper is to indicate the possibility of implementing the concepts of monotonicity analysis in a computer algorithm. The computer program makes the monotonicity decisions. The user is asked to adjust the optimization problem accordingly and takes an active part in the solution process.
Synthesis of Spherical Four-Bar Function Generators to Match Two Prescribed Velocity Ratios
Authors: Chiang C. H.
Published: November 2009

The present problem is a variation of synthesizing spherical four-bar function generators to coordinate three pairs of finitely separated crank-angle displacements. It is to be stressed here that, since the technique is on the basis of equations of three relative poles, the characteristic equation is simply a quadratic equation in the unknown tan ψo (initial output crank angle). It is not necessary, as in the case of a characteristic equation derived from displacement equations, to resort to techniques such as iterative methods for solving nonlinear equations. Equations are so presented as to facilitate computer programing. The synthesis of spherical crank-rockers is a special case of the present problem.
The Spacing of Precision Points in Full-Cycle Mechanism Synthesis
Authors: Haines R. S.
Published: November 2009

In the kinematic or dynamic synthesis of linkage mechanisms by the precision point method, the established procedures for determining the optimal spacing of the precision points break down if the desired performance curve is to be matched over a full cycle of the input crank. Alternative procedures are proposed, both for first approximations to the optimum spacing and for iterative respacing. These procedures have proved successful in a spring balancing problem.
Kinematic Structure and Functional Analysis of Shaft Couplings Involving Pode Joints
Authors: Akbil E. , Lee T. W.
Published: November 2009

This paper introduces some basic concepts and new approaches regarding the kinematic structure and functional analysis of mechanisms. The theory and approach are illustrated on shaft couplings involving pode joints. Kinematic structure of pode joints is given and some new concepts, such as multiple contacting points and effective and idle degrees-of-freedom, are introduced. A systematic approach which includes a modified graph representation and a modified degree-of-freedom equation is presented. Using this approach the mobility analysis of a class of difficult and complex mechanisms can be treated. Several specific examples are presented to illustrate the basic theory.
Energy Efficient Cam-Follower Systems
Authors: Freudenstein F. , Mayourian M. , Maki E. R.
Published: November 2009

The energy loss in cam-follower systems due to friction between moving parts can be a significant contributor to the power loss in machinery. Considering the total number of cam-operated machines in manufacturing and other operations, the energy savings obtainable by improving the efficiency of the average cam-follower system by even a small percentage would be significant. In this investigation a new rating factor—an energy-loss coefficient proportional to the energy loss at the cam-follower interface—has been defined and evaluated. The rating factor relates to energy efficiency in a manner analogous to the way in which the well-known rating factors for velocity, acceleration, and shock relate to the kinematic characteristics of the cam-follower system. Two cam-follower configurations have been considered: 1) a follower motion governed by both cam and return spring, and 2) a follower positively driven by the cam. In both cases it was found that cam curves with identical rise and rise times can differ substantially in energy efficiency thereby demonstrating the significance of an energy-optimization strategy in the design of cam-follower systems. The nature of the functional dependence of the energy loss on system parameters has been identified and a minimum energy-loss limit established.
Into Mesh Lubrication of Spur Gears With Arbitrary Offset Oil Jet. Part 2: For Jet Velocities Equal to or Greater Than Gear Velocity
Authors: Akin L. S. , Townsend D. P.
Published: November 2009

An analysis was conducted for into mesh oil jet lubrication with an arbitrary offset and inclination angle from the pitch point for the case where the oil jet velocity is equal to or greater than gear pitch line velocity. Equations were developed for minimum and maximum oil jet impingement depth. The analysis also included the minimum oil jet velocity required to impinge on the gear or pinion and the optimum oil jet velocity required to obtain the best lubrication condition of maximum impingement depth and gear cooling. It was shown that the optimum oil jet velocity for best lubrication and cooling is when the oil jet velocity equals the gear pitch line velocity. When the oil jet velocity is slightly greater than the pitch line velocity, the loaded side of the driven gear and the unloaded side of the pinion receive the best lubrication and cooling with slightly less impingement depth. As the jet velocity becomes much greater than the pitch line velocity the impingement depth is considerably reduced and may completely miss the pinion.
χ-Theory in Gear Geometry
Authors: Iyoi H. , Ishimura S.
Published: November 2009

In the design of helical gears for pumping action, hydraulic performance is defined by flow rate multiplied by effective work ratio. This is the most important factor in determining the optimum performance. In previous papers, we considered a mathematical model derived mostly from geometrical intuition; however, analytical approach was not completed. In this paper, the optimum design of gear surfaces is thoroughly investigated. It is shown that the optimization of hydraulic performance can be achieved with a particular choice of the parameter χ(y) in the differential equation of meshing gears with parallel axes, where χ(y) is a function characterizing the tooth profile and χ(y) = dφ/d (x/R), φ is rotational angle of rotors, R is the common radius of pitch circles and x, y are coordinates in the plane transverse to gear axes.
On the Spur-Gear Dynamic Tooth-Load Under Consideration of System Elasticity and Tooth Involute Profile
Authors: Bahgat B. M. , Osman M. O. M. , Sankar T. S.
Published: November 2009

A procedure for the dynamic analysis of gears is presented. The procedure is based on Hertz’s impact formula of two cylinders in contact. The radius of curvature at the contact point is considered as an equivalent cylinder radius. A pair of spur gears is used through the analysis. The instantaneous dynamic tooth load is evaluated taking into account the elasticity of each connecting shaft and elasticity of each tooth in contact. Each tooth is considered as a cantilever beam with actual shape of an involute profile. The rigid inertias of existing masses are also included. The dynamic equations presenting the mathematical model are solved using a harmonic series expansion satisfied at three discrete positions during a very small period of time within the contact period. An example is selected such that the arc of contact during the mesh of one pair of teeth corresponds to the circular pitch.
Precision of Spiral-Bevel Gears
Authors: Litvin F. L. , Goldrich R. N. , Coy J. J. , Zaretsky E. V.
Published: November 2009

An analytical method was derived for determining the kinematic errors in spiral-bevel gear trains caused by the generation of nonconjugate surfaces, by axial displacements of the gear assembly, and by eccentricity of the assembled gears. Such errors are induced during manufacturing and assembly. Two mathematical models of spiral-bevel gears were included in the investigation. One model corresponded to the motion of the contact ellipse across the tooth surface (geometry I) and the other along the tooth surface (geometry II). The following results were obtained: 1) Kinematic errors induced by errors of manufacture may be minimized by applying special machine settings. The original error may be reduced by an order of magnitude. The procedure is most effective for geometry II gears. 2) When trying to adjust the bearing contact pattern between the gear teeth for geometry I gears, it is more desirable to shim the gear axially; for geometry II gears, shim the pinion axially. 3) The kinematic accuracy of spiral-bevel drives is most sensitive to eccentricities of the gear and less sensitive to eccentricities of the pinion. The pecision of mounting accuracy and manufacture is most crucial for the gear, and less so for the pinion.
Toothed Belt-Load Distribution
Authors: Naji M. R. , Marshek K. M.
Published: November 2009

A mathematical model was developed to study the effect on belt load distribution of belt material properties, pitch variations, friction force, and pulley rotation. Results are presented which show the influence on load distribution of pitch difference, tight side tension, slack side tension, belt tooth spring constant, and coefficient of friction, for the belt on stationary, driver, and driven pulleys. Data from the mathematical model compared well with experimental results available in the literature.
Metallurgical Factors in Forged and Machined Gear Surface Durability
Authors: Narasimhan S. , Benedict D. K. , Chen Hen-Li , Lehnhoff T. F.
Published: November 2009

Forged and machined bevel gears have been tested to compare surface durability for the two manufacturing processes. The tests and results which showed the machined gears to have 30.6 percent more pitted teeth per gear are discussed in a companion paper. This paper assesses the differences in resistance to pitting fatigue based on metallurgical examination. The gears were manufactured to be as nearly identical as possible and they were subjected to simultaneous heat treatment. Differences in depth of hardness, retained austenite, and grain size are considered to be within normal statistical variations of these parameters, although the sample size was small. The strongest evidence indicates the improved pitting resistance of forged gears is due to the random locations of pit initiation sites. Machined surfaces pit in regular patterns along the tool marks. These pits tend to combine by microcracking more rapidly because the pits are more favorably oriented.
Variable Degree-of-Freedom Component Mode Analysis of Inertia Variant Flexible Mechanical Systems
Authors: Shabana A. , Wehage R. A.
Published: November 2009

A method is presented for transient dynamic analysis of mechanical systems composed of interconnected rigid and flexible bodies that undergo large angular displacements. Gross displacement of elastic bodies is represented by superposition of local linear elastic deformation on nonlinear displacement of body reference coordinate systems. Flexible bodies are thus represented by combined sets of reference and local elastic generalized coordinates. Modal analysis and sub-structuring of the local elastic system identifies all modes and allows for elimination of insignificant modes. Equations of motion and constraints are formulated in terms of minimum mixed sets of modal and reference generalized coordinates, and dynamically adjusted to a time and interia-variant eigenspectrum. A flexible mechanical linkage and a tracked vehicle with a flexible gun tube are simulated to illustrate the method.
Optimal Flywheel Design With a General Thickness Form Representation
Authors: Sandgren E. , Ragsdell K. M.
Published: November 2009

A general solution procedure is described for the optimal design of flywheel forms. A continuously differentiable thickness function is developed with undetermined coefficients and closed form solutions for the volume and kinetic energy derived. The two-point boundary value problem which results from the solution of the differential equation for the radial and tangential stresses is solved by the shooting method. The stress components are then combined to form the total stress at each radial location through the application of distortion energy theory. The problem is then formulated as a nonlinear programming problem and solved for various design objectives including minimizing the flywheel volume, maximizing the kinetic energy, and minimizing the stress deviations from the limiting design stress.
Prevention of Impact in Bearings of Four-Bar Linkages
Authors: Perera O. , Seering W.
Published: November 2009

The loss of pin contact in bearings of four bar-linkages, and the avoidance of impact within a bearing through prevention of contact loss are both investigated in this study. Conditions prevailing during contact loss are identified. A simple, inexpensive method for eliminating contact loss and subsequent impact is presented and evaluated.
Symbiotic Nitrogen Fixation in the Fungus Gardens of Leaf-Cutter Ants
Authors: Pinto-Tomás Adrián A. , Anderson Mark A. , Suen Garret , Stevenson David M. , Chu Fiona S. T. , Cleland W. Wallace , Weimer Paul J. , Currie Cameron R.
Published: November 2009

Gardening for Ants and Termites

Among the social insects, ants and termites are the most diverse and ecologically dominant. Termites are known to engage in a mutualism with nitrogen-fixing bacteria, and

Pinto-Tomás
et al.

(p.
1120
) have identified similar relationships occurring among leaf-cutter ants, which maintain specialized nitrogen-fixing bacteria in their fungus gardens. Together, these mutualisms are a major source of nitrogen in terrestrial ecosystems. How is the evolutionary stability of such mutualistic cooperation maintained?

Aanen
et al.

(p.
1103
) show that the
Termitomyces
fungus cultured by termites remains highly related because mycelia of the same clone fuse together and grow more efficiently to out-compete rare clones.
Aragonite Undersaturation in the Arctic Ocean: Effects of Ocean Acidification and Sea Ice Melt
Authors: Yamamoto-Kawai Michiyo , McLaughlin Fiona A. , Carmack Eddy C. , Nishino Shigeto , Shimada Koji
Published: November 2009

Acidic Ocean

One consequence of the historically unprecedented level of CO
2
in the atmosphere that fossil fuel burning has caused, in addition to a warmer climate, is higher concentrations of dissolved CO
2
in the oceans. This dissolved CO
2
makes the oceans more acidic, and thus less saturated with respect to calcium carbonate. This has important ramifications for organisms that have calcium carbonate skeletons, which depend for their survival on the saturation state of calcium carbonate in the waters where they live.

Yamamoto-Kawai
et al.

(p.
1098
) report that in 2008, surface waters of the Canada Basin became undersaturated with respect to aragonite, a relatively soluble form of calcium carbonate incorporated into the shells or skeletons of many types of marine plankton and invertebrate. This undersaturation occurred much sooner than had been anticipated and has important implications for the composition of the Arctic ecosystem.
Geophysical Detection of Relict Metasomatism from an Archean (~3.5 Ga) Subduction Zone
Authors: Chen Chin-Wu , Rondenay Stéphane , Evans Rob. L. , Snyder David B.
Published: November 2009

Building Early Continents

Cratons, the roots of Earth's continents, have survived billions of years of accretion, volcanism, and plate motion. Due to this tumultuous history, existing evidence for how and when they formed is hard to find.

C.-W. Chen
et al.

(p.
1089
) use geophysical data collected below the Slave craton in Canada to show that subduction of lithospheric plates in the Archean may have been a major process that controlled its assembly. Spatially aligned seismic and conductive discontinuities over 100 kilometers below the surface are caused by minerals that formed from hot fluids generated as ancient crust melted at a subduction zone. Other old cratons on Earth show similar features, suggesting plate tectonics was operating at least 3.5 billion years ago.
The Schizophrenia Susceptibility Gene
dysbindin
Controls Synaptic Homeostasis
Authors: Dickman Dion K. , Davis Graeme W.
Published: November 2009

Dysbindin Function in Synaptic Homeostasis

Homeostatic signaling systems are widely believed to stabilize neural function over prolonged periods of time. However, the molecular mechanisms of homeostatic signaling in the nervous system are largely unknown, and direct links between defective homeostatic signaling and disease-causing genes remain obscure.
Dickman and Davis
(p.
1127
) performed a large-scale, electrophysiology-based genetic screen for mutations that specifically disrupt synaptic homeostasis. DTNBP1 is one of two genes that are most strongly and consistently associated with schizophrenia susceptibility in humans. The
Drosophila
homolog of DTNBP1 (dysbindin) was identified in the screen and was found to function during synapse development, baseline neurotransmission, and synaptic homeostasis. Dysbindin altered the calcium-dependence of vesicle release and was essential in the presynaptic neuron for both the induction and expression of synaptic homeostasis.
Selfless Memes
The Age of Empathy
Nature's Lessons for a Kinder Society

by Frans de Waal

Harmony, New York, 2009. 304 pp. $25.99, £19.99. ISBN 9780307407764.
Authors: Bolhuis Johan J.
Published: November 2009

De Waal uses observations from his own fieldwork to argue for the importance of empathy in social behavior of human and other animals.
Preferences and Penalties Differ
The Mathematics of Sex
How Biology and Society Conspire to Limit Talented Women and Girls

by Stephen J. Ceci and Wendy M. Williams

Oxford University Press, New York, 2009. 286 pp. $34.95, £22.50. ISBN 9780195389395.
Authors: Miller Raegen T.
Published: November 2009

Surveying and evaluating the scientific literature gender disparities in mathematics, science, and engineering disciplines, Ceci and Williams argue that the underrepresentation of women in these fields is due to "certain choices that women (but not men) are compelled to make in our society."
Clean Pigs Offer Alternative to Stem Cell Transplants
Authors: Holden Constance
Published: November 2009

Within a couple of years, a scientific team hopes to start clinical trials using cells from the first swine herd in the country specially bred to supply insulin-secreting pancreatic islets for people with diabetes. But they face immunological and regulatory challenges, as well as the challenge of overcoming public aversion to the idea.
Eco-Alchemy in Alberta
Authors: Kean Sam
Published: November 2009

The oil of the future—vast and largely untapped reserves of petroleum in the form of tarry deposits a few tens of meters beneath the surface—has serious reclamation challenges right now.
Better Homes and Hearths, Neandertal-Style
Authors: Balter Michael
Published: November 2009

Detailed studies of Neandertal hearths and living quarters suggest that, like modern humans, our extinct cousins had the knack for organization.
A Question of Balance
Authors: Pennisi Elizabeth
Published: November 2009

Researchers have proposed that genes that code for proteins that are part of complexes are most likely to survive the purging that follows whole-genome duplications. Increasing evidence from the 9th International Plant Molecular Biology Congress and other meetings suggests that this so-called gene balance hypothesis may be correct.
Role of a novel bile acid receptor TGR5 in the development of oesophageal adenocarcinoma
Authors: Hong Jie , Behar Jose , Wands Jack , Resnick Murray , Wang Li Juan , DeLellis Ronald A , Lambeth David , Souza Rhonda F , Spechler Stuart J , Cao Weibiao
Published: November 2009

Background and aims

Mechanisms of the progression from Barrett's oesophagus to oesophageal adenocarcinoma (OA) are not fully understood. Bile acids may have an important role in this progression. This study aimed at examining the role of NADPH oxidase NOX5-S and a novel bile acid receptor TGR5 in taurodeoxycholic acid (TDCA)-induced increase in cell proliferation.

Methods

Human Barrett's cell line BAR-T and OA cell line FLO were transfected by the Lipofectamine 2000 or Amaxa-Nucleofector-System. mRNAs were measured by real-time PCR. H2O2 was measured by a fluorescent assay. Cell proliferation was determined by measurement of thymidine incorporation.

Results

NOX5-S was present in FLO cells. TDCA significantly increased NOX5-S expression, H2O2 production and thymidine incorporation in FLO and BAR-T cells. This increase in thymidine incorporation was significantly reduced by knockdown of NOX5-S. TGR5 mRNA and protein levels were significantly higher in OA tissues than in normal oesophageal mucosa or Barrett's mucosa. Knockdown of TGR5 markedly inhibited TDCA-induced increase in NOX5-S expression, H2O2 production and thymidine incorporation in FLO and BAR-T cells. Overexpression of TGR5 significantly enhanced the effects of TDCA in FLO cells. TGR5 receptors were coupled with Gαq and Gαi3 proteins, but only Gαq mediated TDCA-induced increase in NOX5-S expression, H2O2 production and thymidine incorporation in FLO cells.

Conclusions

TDCA-induced increase in cell proliferation depends on upregulation of NOX5-S expression in BAR-T and FLO cells. TDCA-induced NOX5-S expression may be mediated by activation of the TGR5 receptor and Gαq protein. These data may provide potential targets to prevent and/or treat Barrett's OA.
Myxosoma cerebralis: Trypsinization of Plankton Centrifuge Harvests Increases Optical Clarity and Spore Concentration
Authors: Markiw Maria E. , Wolf Ken
Published: November 2009

Pepsin, pronase, and trypsin were compared for their ability to digest the tissue residues that constitute the overwhelming mass of plankton centrifuge harvests. Trypsin was preferred; a treatment with 0.25% for 30 min at pH 7.2–7.5 released an average of 22% additional spores and resulted in an average 11-fold increase in spore concentration. The procedure significantly enhances the sensitivity of spore detection by the plankton centrifuge method.Key words: Myxosoma cerebralis, myxosporidans, spore detection
Differentiation in Coregonus zenithicus in Lake Superior
Authors: Todd Thomas N. , Smith Gerald R.
Published: November 2009

Morphological variation in Coregonus zenithicus has long plagued biologists working on Lake Superior ciscoes. Some of this variation is due to allometric growth; earlier workers incorrectly recognized large C. zenithicus as a distinct species, C. nigripinnis cyanopterus. Coregonus reighardi dymondi is a variant of C. zenithicus in northern bays of Lake Superior and Lake Nipigon. The morphological differences between members of spring and fall spawning populations of C. zenithicus in Lake Superior are no greater than those between geographically separate populations. We conclude that spawning time and geographic isolation act similarly in effecting differentiation of coregonine populations, and that populations with different spawning times do not necessarily represent different species.Key words: Coregonus zenithicus, cisco, Great Lakes, multivariate morphometrics, endangered species, taxonomy
Variability in the Diet of Ringed Seals, Phoca hispida, in Alaska
Authors: Lowry Lloyd F. , Frost Kathryn J. , Burns John J.
Published: November 2009

Analysis of stomach contents of ringed seals (Phoca hispida) collected at eight locations along the Alaskan coast showed significant seasonal and regional differences in diet. During the spring–summer period saffron cod (Eleginus gracilis) was the most important food item in the nearshore zone of the northeastern Bering and southeastern Chukchi Seas. In that period shrimps (Pandalus spp., Eualus spp., Lebbeus polaris, and Crangon septemspinosa) were the major food in the northcentral Bering Sea, hyperiid amphipods (Parathemisto libellula) in the central Beaufort Sea and euphausiids (Thysanoessa spp.) in the boundary region (Barrow area) between the Chukchi and Beaufort seas. During late summer–early autumn hyperiid amphipods were important foods in the central Beaufort and the southeastern Chukchi. The autumn diet of seals in Norton Sound included mainly saffron cod During winter–early spring Arctic cod (Boreogadus saida) predominated the diet at all localities. During spring and early summer in the northeastern Bering and southeastern Chukchi seas the amount of saffron cod consumed was directly correlated with age. In the Beaufort Sea during autumn and winter Arctic cod were eaten in similar amounts by all age-classes. An analysis of the energy value and quantities of prey consumed indicates that prey species that occur in concentrations (Arctic and saffron cods, hyperiid amphipods, euphausiids and some shrimps) are of particular importance in the annual nutrition of ringed seals. These seals may be food limited in areas and during times when these kinds of prey are not available.Key words: food habits, Phoca hispida, ringed seals, Arctic cod, saffron cod, crustaceans, Alaska
Importance of Feeding, Direct Uptake from Seawater, and Transfer from Generation to Generation in the Accumulation of an Organochlorine (p,p′-DDT) by the Marine Planktonic Copepod Calanus finmarchicus
Authors: Harding Gareth C. , Vass W. Peter , Drinkwater Ken F.
Published: November 2009

The accumulation of an organochlorine by the marine copepod Calanus finmarchicus, through feeding on contaminated phytoplankton, 14C-p,p′-DDT labeled Thalassiosira weisflogii, was measured. At "normal" densities, ≈ 60 μg C/L, the copepod retained 60–70% of the DDT ingested following gut egestion, but under "bloom" conditions, ≈ 600 μg C/L, retained as little as 10%. These results enable us to incorporate feeding and generation transfer terms into an earlier model of DDT flux between seawater and planktonic crustaceans. Model simulations indicate that it is not necessary to invoke direct uptake from seawater to arrive at published levels of ΣDDT in copepods, even when our lowest experimental DDT feeding efficiencies are used. We predict that the potential for rapidly developing Calanus to accumulate DDT from generation to generation will reach an equilibrium concentration after 12 generations but that an alternating equilibrium of generations will occur within four generations in a two-season temperature environment.Key words: p,p′-DDT, uptake, clearance, feeding, assimilation, copepods, Calanus finmarchicus
Variable Gut Residence Time: Problems in Inferring Feeding Rate from Stomach Fullness of a Mysid Crustacean
Authors: Murtaugh Paul A.
Published: November 2009

The gut residence time of the mysid crustacean Neomysis mercedis is extremely variable and is negatively correlated with ingestion rate. In two experiments in which mysids were fed copepod meals followed by continuous exposure to Daphnia, passage times varied from less than 1 to more than 13 h, and there were significant negative correlations of both copepod and daphnid passage times with the average feeding rate on Daphnia. In a third experiment starved mysids retained significant amounts of material in the stomach for more than 3 d. This dependence of evacuation rate on feeding activity may invalidate attempts to infer absolute or relative ingestion rate from the stomach fullness of field-caught animals.
Generalized Stock Reduction Analysis
Authors: Kimura Daniel K. , Balsiger James W. , Ito Daniel H.
Published: November 2009

In this paper we generalize Stock Reduction Analysis (SRA) so that the model now allows for growth in the fishable biomass, and variable recruitment to the fishable biomass. The application of R. B. Deriso's delay-difference equation to SRA allows for growth, and also provides justification for using a biomass based model. Variable recruitment is introduced into SRA using both a stock–recruitment relationship and exogenous variables. We present general methods for obtaining unique solutions to the SRA equations, and give a new method for calculating the equilibrium sustainable yield curve. By applying the generalized SRA model to Pacific ocean perch (Sebastes alutus) stocks in the Gulf of Alaska, we conclude that the sustainable yield from this stock is smaller than previously estimated.
Demographic Consequences of Precocious Maturation of Atlantic Salmon (Salmo salar)
Authors: Myers R. A.
Published: November 2009

Detailed records of outgoing smolts of Atlantic salmon (Salmo salar) and estimates of the parr population that produced them were used to study the demographic conequences of male precocious sexual maturation in southwest Newfoundland. Approximately 80% of males matured precociously in the stream. Annual survival probability of a male that reproduces precociously is reduced by a median 44%. Precocious maturation delays smolting; the probability of smolting in the second year for a male precocious parr is approximately 13% of that of a female. The economic loss due to precocious maturation is large; 60% of the adult male salmon production is lost due to precocious maturation.
Multiattribute Analysis and the Concept of Optimum Yield
Authors: Healey M. C.
Published: November 2009

This paper reviews the origin and operational definition of the optimum yield (OY) concept and demonstrates how techniques of decision analysis can provide an analytical model for OY. The concept of OY was formalized as the guiding principle of fisheries management in the United States and Canada in 1976. The policies of both countries make it clear that a wide range of biological, economic, and social factors are to be taken into account in determining OY. Confusion exists, however, about precisely which of these factors should determine OY in any fishery and what is their relative importance. Uncertainty also exists about how to take biological, economic, and social factors jointly into account as the concept of OY implies one must. Established biological and economic models in fisheries are not adequate for such an analysis because their focus is single- rather than multi-objective. Operational techniques of decision analysis, such as multiattribute utility analysis, are specifically designed to deal with multiobjective problems like OY. I propose that a simple, linear, utility model be used to assess the optimality of alternative yield strategies in fisheries management. I illustrate the application of the model by assessing OY options in the New England herring (Clupea harengus) fishery and the Skeena River salmon (Oncorhynchus spp.) fishery. The advantages of the model are that it is simple and intuitively appealing, that it permits a wide range of types and qualities of data to be incorporated into the evaluation of management options, that it is amenable to sensitivity analysis, and that it is adaptable to a variety of decision rules.
A NOTE ON MATRIX MODEL WITH IR CUTOFF AND AdS/CFT
Authors: DEY TANAY K. , MUKHERJI SUDIPTA , MUKHOPADHYAY SUBIR , SARKAR SWARNENDU
Published: November 2009

We study effective gauge theory at finite temperature on a three-sphere in the presence of an IR cutoff using AdS/CFT. Comparing with the thermodynamic behavior of its gravity dual, we analyze a phenomenological matrix model which describes the gauge theory in the strongly coupled regime. Subsequently, we study the behavior of the model as a function of the IR cutoff. We further argue that a similar matrix model represents the effective gauge theory on R3 with an IR-cutoff and analyze the model numerically.
BEARING FAULT DETECTION USING VIRTUAL–BASED ICA ALGORITHM
Authors: MOGHADAM K. REZAEI , ARIAEI A. MOHAJERIN , KAHAEI M. H. , POSHTAN J.
Published: November 2009

This paper presents a new method for fault diagnosis in ball-bearings using a combination of the Independent Component Analysis (ICA) and the Wavelet Transform. In the ICA, the number of sensors should be equal to the number of independent sources. We introduce a new method to replace the second vibration signal required by the ICA by a virtual one in order to increase the accuracy of the diagnosing system and also to simplify the system hardware. Using real and simulated signals, it is shown that the proposed algorithm outperforms the HFD algorithm.
Rhythmic changes in colonic motility are regulated by period genes
Authors: Hoogerwerf Willemijntje A. , Shahinian Vahakn B. , Cornélissen Germaine , Halberg Franz , Bostwick Jonathon , Timm John , Bartell Paul A. , Cassone Vincent M.
Published: November 2009

Human bowel movements usually occur during the day and seldom during the night, suggesting a role for a biological clock in the regulation of colonic motility. Research has unveiled molecular and physiological mechanisms for biological clock function in the brain; less is known about peripheral rhythmicity. This study aimed to determine whether clock genes such as period 1 ( per1) and period2 ( per2) modulate rhythmic changes in colonic motility. Organ bath studies, intracolonic pressure measurements, and stool studies were used to examine measures of colonic motility in wild-type and per1per2 double-knockout mice. To further examine the mechanism underlying rhythmic changes in circular muscle contractility, additional studies were completed in neuronal nitric oxide synthase (nNOS) knockout mice. Intracolonic pressure changes and stool output in vivo, and colonic circular muscle contractility ex vivo, are rhythmic with greatest activity at the start of night in nocturnal wild-type mice. In contrast, rhythmicity in these measures was absent in per1per2 double-knockout mice. Rhythmicity was also abolished in colonic circular muscle contractility of wild-type mice in the presence of Nω-nitro-l-arginine methyl ester and in nNOS knockout mice. These findings suggest that rhythms in colonic motility are regulated by both clock genes and a nNOS-mediated inhibitory process and suggest a connection between these two mechanisms.
Obesity, asthma, and oxidative stress
Authors: Holguin Fernando , Fitzpatrick Anne
Published: November 2009

Obesity is associated with increased systemic and airway oxidative stress, which may result from a combination of adipokine imbalance, comorbidities, and reduced antioxidant defenses. While obesity-mediated increased oxidative stress plays an important role in the pathogenesis of vascular disease and nonalcoholic hepatic steatosis, little is known of how it may affect the lung. Contrary to what has previously been thought, the combination of obesity and asthma, both chronic inflammatory diseases, does not necessarily result in a synergistic effect, leading to even greater oxidative stress. However, most available studies have compared the levels of oxidative stress biomarkers on stable asthma patients, and it is possible that the interaction of oxidative stress between obesity and asthma is not readily detectable under basal conditions. We propose that obesity-mediated oxidative stress, which may affect the lung function of asthmatic subjects by increasing airway inflammation and reducing the effectiveness of inhaled corticosteroids, may become evident during exposure to an aggravating factor or during periods of asthma exacerbation. Understanding whether obesity-mediated oxidative stress has a mechanistic role in the association between obesity and asthma will help in the formation of public health policies and increase our capacity to develop therapeutic interventions that improve the life of obese asthmatic subjects.