bluuebunny/crossref_metadata_2025 huggingface dataset:
Food Production and Water Conservation in a Recirculating Aquaponic System in Saudi Arabia at Different Ratios of Fish Feed to Plants
Authors: Al‐Hafedh Yousef S. , Alam Aftab , Beltagi Mohamed Salaheldin
Published: July 2008

An indoor aquaponic system (i.e., the integration of fish culture with hydroponic plant production in a recirculating setup) was operated for maximizing water reuse and year‐round intensive food production (Nile tilapia, Oreochromis niloticus, and leaf lettuce) at different fish feed to plants ratios. The system consisted of a fish culture component, solid removal component, and hydroponic component comprising six long channels with floating styrofoam rafts for holding plants. Fish culture effluents flowed by gravity from the fish culture component to the solid removal component and then to the hydroponic component. Effluents were collected in a sump from which a 1‐horsepower in‐line pump recirculated the water back to the fish culture tanks at a rate of about 250 L/min. The hydroponic component performed as biofilter and effectively managed the water quality. Fish production was staggered to harvest one of the four fish tanks at regular intervals when fish attained a minimum weight of 250 g. Out of the total eight harvests in 13 mo, net fish production per harvest averaged 33.5 kg/m3 of water with an overall water consumption of 320 L/kg of fish produced along with the production of leaf lettuce at 42 heads/m2 of hydroponic surface area. Only 1.4% of the total system water was added daily to compensate the evaporation and transpiration losses. A ratio of 56 g fish feed/m2 of hydroponic surface effectively controlled nutrient buildup in the effluents. However, plant density could be decreased from 42 to 25–30 plants/m2 to produce a better quality lettuce.
Replacement of Soybean Meal in Channel Catfish, Ictalurus punctatus, Diets with Cottonseed Meal and Distiller’s Dried Grains with Solubles
Authors: Robinson Edwin H. , Li Menghe H.
Published: July 2008

Two pond experiments were conducted to evaluate cottonseed meal (CSM), distiller’s dried grains with solubles (DDGS), and supplemental lysine as replacements for soybean meal (SBM) in channel catfish diets. In Experiment 1, fish fed diets in which SBM was totally replaced with CSM gained similar weight as fish fed control diet, but fish fed CSM diet in Experiment 2 had 9.5% lower weight gain than fish fed control diet. In both experiments, feed conversion increased significantly for fish fed CSM diet. There were no consistent trends in body composition of fish fed CSM diet versus control diet. Fish fed the DDGS + SMB diet had higher (Experiment 1) or similar (Experiment 2) weight gain than fish fed control diet. Feed conversion ratio was significantly lower in both experiments for fish fed SBM + DDGS diet than that of fish fed control diet. Body fat tended to be higher in fish fed SBM + DDGS diet compared to fish fed control diet. It appears that about 50% of SBM can be replaced with CSM + lysine in catfish diets without negatively affecting fish performance. Further, DDGS can be used up to at least 30% when the diet is supplemented with lysine.
Partial splenic embolization prior to combination therapy of interferon and ribavirin in chronic hepatitis C patients with thrombocytopenia
Authors: Miyake Yasuhiro , Ando Masaharu , Kaji Eisuke , Toyokawa Tatsuya , Nakatsu Morihito , Hirohata Mamoru
Published: July 2008

Aim: A low platelet count leads to dose reduction of interferon (IFN) and is associated with failure to achieve a sustained virological response (SVR) in chronic hepatitis C patients. However, partial splenic embolization (PSE) is effective for treating thrombocytopenia resulting from hypersplenism.

Methods: We compared the clinical features of 10 patients receiving PSE prior to the combination therapy of IFN and ribavirin (RBV) (PSE group) with those of 10 non‐receiving PSE patients (non‐PSE group).

Results: In all 10 patients, PSE was successfully performed without serious adverse events. After PSE, leukocyte, neutrophil, and platelet counts significantly increased. The period from PSE to the initiation of the combination therapy was 15 (7–21) days. In the PSE group, two of six patients (33%) infected with genotype 1, and all four patients infected with genotype 2, achieved SVR. In the non‐PSE group, only three patients infected with genotype 2 achieved SVR. Two patients in the PSE group and one in the non‐PSE group discontinued the combination therapy. Three patients of the PSE group and five of the non‐PSE group reduced the dose of pegylated IFN‐α‐2b because of thrombocytopenia. In the PSE group, platelet counts during the combination therapy fell to baseline levels; however, they did not fall to lower levels than baseline levels. In the non‐PSE group, platelet counts 1 month after the initiation of the therapy were lower than baseline levels.

Conclusion: The increase of platelet counts after PSE may allow the safe use of IFN and RBV and improve the SVR rate in chronic hepatitis C patients with thrombocytopenia.
Scale-Dependent Homogenization of Inelastic Random Polycrystals
Authors: Ranganathan Shivakumar I. , Ostoja-Starzewski Martin
Published: July 2008

Rigorous scale-dependent bounds on the constitutive response of random polycrystalline aggregates are obtained by setting up two stochastic boundary value problems (Dirichlet and Neumann type) consistent with the Hill condition. This methodology enables one to estimate the size of the representative volume element (RVE), the cornerstone of the separation of scales in continuum mechanics. The method is illustrated on the single-phase and multiphase aggregates, and, generally, it turns out that the RVE is attained with about eight crystals in a 3D system. From a thermodynamic perspective, one can also estimate the scale dependencies of the dissipation potential in the velocity space and its complementary potential in the force space. The viscoplastic material, being a purely dissipative material, is ideally suited for this purpose.
Assessment of the Twice-Yield Method for Elastic-Plastic Fatigue Analysis
Authors: Reinhardt W.
Published: July 2008

The twice-yield (2 Sy) method was proposed by Kalnins as a convenient method to perform an elastic-plastic fatigue analysis using Finite Element analysis. With this method, only a single loading half cycle needs to be run. However, since the shape of the effective yield surface used in this method deviates from the actual von Mises yield surface, the method may conceivably deviate from the solution obtained by elastic-plastic cycle-by-cycle analysis. This paper aims to evaluate the twice-yield method for elastic-plastic fatigue analysis, which is conventionally done cycle-by-cycle. It compares the predictions of plastic strain from the twice-yield method and cycle-by-cycle analysis using some generic examples with non-proportional loading histories as they are frequently encountered in practice.
Development of EPFM Procedure for Axially Flawed Pipe Using Z Factor Based on CVN
Authors: Hasegawa Kunio , Miyazaki Katsumasa , Miura Naoki , Kashima Koich , Scarth Douglas A.
Published: July 2008

Evaluation procedures on an allowable axial flaw in a pipe for fully plastic fracture is provided by limit load criteria in Appendix C-5000 of the ASME Code Section XI. However, flaw evaluation for ductile fracture using EPFM (Elastic Plastic Fracture Mechanics) criteria is not provided for axial flaw in the Appendix. Methodology of the flaw evaluation for ductile fracture using EPFM criteria is discussing at the Working Group on Pipe Flaw Evaluation of ASME Code Section XI. Many failure experiments on axially flawed pressurized pipes made of moderate toughness materials had been performed at Battelle Columbus Laboratories. Semi-empirical equations for predicting failure stresses were developed from these experiments. This paper describes a derivation of load multiplier, Z factor, based on Charpy V notch upper shelf energy (CVN) from failure stresses for moderate toughness materials based on the experiments, and proposes a flaw evaluation procedure to determine allowable axial flaw for a ductile fractured pipe using the EPFM criteria.
Proximity Rules for Subsurface Transforming to Surface Flaws for Class 1 Ferritic Vessels
Authors: Hasegawa Kunio , Miyazaki Katsumasa , Scarth Douglas A. , Cipolla Russell C.
Published: July 2008

There is a rule in Acceptance Standards of Class 1 ferritic vessel in the ASME B&PV Code Section XI describing that allowable subsurface flaws near a component surface are transformed to allowable surface flaws. This is the proximity rule for the subsurface flaws. Allowable sizes of the subsurface flaws decrease with proximity to the component surface. Therefore, a subsurface flaw allowed in the component is not allowed if the same size subsurface flaw is slightly closer to the component surface. However, if the subsurface flaw with the same size is located closer to the component surface, the subsurface flaw not allowed close to the component surface is acceptable after transforming it to a surface flaw. This is a discontinuity of a subsurface flaw. This paper describes the discontinuity problems of the subsurface flaws transforming to surface flaws and proposes a new flaw-to-surface factor of proximity rule, minimizing the influence of the current allowable flaw sizes in the Acceptance Standards.
Limit Load Analysis of Cracked Components Using the Reference Volume Method
Authors: Adibi-Asl R. , Seshadri R.
Published: July 2008

Cracks and flaws occur in mechanical components and structures, and can lead to catastrophic failures. Therefore, integrity assessment of components with defects is carried out. This paper describes the Elastic Modulus Adjustment Procedures (EMAP) employed herein to determine the limit load of components with cracks or crack-like flaw. On the basis of linear elastic Finite Element Analysis (FEA), by specifying spatial variations in the elastic modulus, numerous set of statically admissible and kinematically admissible distributions can be generated, to obtain lower and upper bounds limit loads. Due to the expected local plastic collapse, the reference volume concept is applied to identify the kinematically active and dead zones in the component. The Reference Volume Method is shown to yield a more accurate prediction of local limit loads. The limit load values are then compared with results obtained from inelastic finite element analysis. The procedures are applied to some practical components with cracks in order to verify their effectiveness in analyzing crack geometries. The analysis is then directed to geometries containing multiple cracks and three-dimensional defect in pressurized components.
Finite Element Analysis of Turning Hardened AISI 42100 Bearing Steel With Various Cutting Inserts
Authors: Qian Li , Lei Shuting , Chen Renji
Published: July 2008

Finite element simulations of high-speed orthogonal machining were performed to study the finish hard-turning process as a function of cutting speed, feed rate, cutter geometry, and workpiece hardness. The finish hard-turning process is defined as turning materials with hardness higher than 40 HRC (Hardness – Rockwell C), under appropriate high feed rate and low depth of cut conditions. In the simulations, properties representative of AISI 52100 bearing steel hardened to 45, 51 or 58 HRC were assumed for the workpiece. Cubic boron nitride (CBN), titanium aluminum nitride (TiAlN)-coated carbide cutters, and ceramics inserts are widely used as cutting tool material in such high-speed machining of hardened tool steels — due to high hardness, high abrasive wear resistance, and chemical stability at high temperature. The numerical simulations or experiments assumed physical, mechanical, and thermal properties representative of each of the three cutting materials. Cutting forces, tool and workpiece temperature, and residual stresses were determined in the numerical simulations. These resulting trends in forces, temperatures, and residual stress are consistent with experimental results reported in the literature.
Aging Management Program of Large Diameter Safety Class Piping
Authors: Faidy Claude
Published: July 2008

Ageing management of Nuclear Power Plants is an essential issue for utilities, in term of safety and availability and corresponding economical consequences. Practically all nuclear countries have developed a systematic program to deal with ageing of components on their plants. This paper presents the ageing management program developed by EDF (Electricite´ de France) that are compared with different approaches in other countries, like IAEA (International Atomic Energy Agency)guidelines and GALL (Generic Ageing Lessons Learned) report. The paper presents an example of application to large diameter safety class piping. Different degradation mechanisms are considered fatigue, corrosion and thermal ageing. Maintenance and surveillance actions are also discussed in the paper.
FEM Stress Analysis and an Evaluation of the Sealing Performance in Non-Circular Flange Connections With Gaskets Subjected to Internal Pressure
Authors: Sawa Toshiyuki , Kurosawa Ryo , Maezaki Wataru
Published: July 2008

The contact gasket stress distributions of a non-circular flange connection with a compressed sheet gasket subjected to internal pressure were analyzed taking into account of the hysteresis behavior of the gasket by using the finite element method (FEM). Leakage tests were also conducted using an actual non-circular flange connection with a compressed sheet gasket under internal pressure. Using the contact gasket stress distributions and the results of the leakage tests, the new gasket constants were calculated. The difference in the new gasket constants between the values obtained from the present study and those by the PVRC procedure was substantial. In addition, a method to determine the initial clamping bolt force (bolt preload) for a given tightness parameter was demonstrated.
Supplementary Technical Basis for ASME Section XI Code Case N-597-2
Authors: Scarth Douglas A. , Hasegawa Kunio , Goyette Lee F. , Rush Phil
Published: July 2008

Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code provides rules and requirements for maintaining pressure boundary integrity of components, piping, and equipment during the life of a nuclear power plant. Code Case N-597-2 of Section XI, Requirements for Analytical Evaluation of Pipe Wall Thinning, provides evaluation procedures and acceptance criteria to justify continued operation of Class 1, 2 and 3 piping items subjected to wall thinning by a mechanism such as flow-accelerated corrosion. The acceptance criteria ensure that margins equivalent to those of the ASME B&PV Code are maintained. The technical basis for Code Case N-597-2 was previously presented at the 1999 ASME Pressure Vessels and Piping Conference. Since then, the ASME Section XI Working Group on Pipe Flaw Evaluation has identified the need for further explanation of the technical basis for the Code Case, such as the procedures for evaluation of wall thickness less than the Construction Code Design Pressure-based minimum allowable wall thickness, tmin. This paper provides an additional description of the Code Case technical basis and validation against experimental and historic wall thinning events.
Dynamic Relaxation and New Periodic Symmetry Technique for Simulating Interactions Between Dislocations
Authors: Pan Li , Niewczas Marek
Published: July 2008

Studies of the interaction between two edge dislocations have been carried out by coupled Dynamic Relaxation (DR) technique, the Embedded Atom method (EAM) potential function and a newly developed periodic symmetry method. The effects of boundary conditions and external tractions are examined for the case of edge dislocations with the same or opposite Burgers vectors gliding on physically the same planes, and for dislocations with opposite Burgers vectors gliding on parallel planes. The results show that as expected, edge dislocations dissociate into Shockley partials to minimize their energy. Depending upon the sign of the Burgers vector of component dislocations, various defect configurations are obtained after the relaxation. A more stable defect configuration replaces the well-known structure of the perfect dipole when the distance between the slip planes decreases. This leads to the formation of faulted dipoles in Z configuration. The relaxation results depend upon parameters such as dipole height, initial dipole configuration and also external tractions applied to the system. These parameters together with the atomistic mechanism of transformation of perfect dipole into the Z dipole are studied. The suitability of the technique for simulating complex defect structures in crystalline material is discussed.
Stock Effects on Exceptional Maintenance Tasks Taking Into Account Risks
Authors: Lonchampt J. , Domecq C. , Bauby C. E.
Published: July 2008

Exceptional maintenance tasks are maintenance tasks that are unlikely to be carried out more than once or twice over the life of a Nuclear Power Plant. Such a task may be preventive or corrective toward a wearing mechanism that may lead to a failure with a low probability and high potential consequences. Exceptional maintenance tasks are often characterized by a long lead-time and a high cost, that’s why in addition to the classic maintenance issue on choosing between preventive or corrective tasks, it is very important for exceptional maintenance to evaluate the best stock level. This paper describes the methodology and tools that are being developed at EDF and presents a case study that has been carried out.
Interaction of Twin Non-Aligned Through-Wall Flaws Under Elastic-Plastic Conditions
Authors: Bezensek B. , McCulloch E.
Published: July 2008

Elastic-plastic calculations have been performed for the geometry containing twin non-aligned through-wall flaws in tension. Such geometries develop localised shear flow fields in which neighbouring flaws interact over much larger separations than currently allowed for in the codes [1–3] under elastic-plastic conditions. J values have been obtained in the annular zone spanning directions directly ahead of the crack, to the geometric angle which connects the two crack tips. It was found that elastic-plastic conditions give rise to a local mixed mode problem, where maximum J values rotate off the plane of the flaw, towards the neighbouring flaws. Interaction factors have been defined by comparing elastic-plastic stress intensity factors for twin flaw configuration with the values for the single flaw. A significant interaction has been observed for geometries with vertical separation less than the length of the flaw (H<L). Interaction based on the ratio of the local to global limit loads has also been examined and shows interaction up to the vertical separations of H=1.5L, largely independent of the horizontal separation.
Coupled Finite Element-Moving Least Squares Technique for Stochastic Structural Response of Cracked Structures
Authors: Aravinda Priyadrashini K. , Rao B. N.
Published: July 2008

In recent years, a class of Galerkin-based meshfree or meshless methods have been developed that do not require a structured mesh to discretize the problem, such as the element-free Galerkin method, and the reproducing kernel particle method. These methods employ a moving least-squares (MLS) approximation method that allows resultant shape functions to be constructed entirely in terms of arbitrarily placed nodes. These methods employ a moving least-squares approximation method that allows resultant shape functions to be constructed entirely in terms of arbitrarily placed nodes. Meshless discretization presents significant advantages for modeling fracture propagation. By sidestepping remeshing requirements, crack-propagation analysis can be dramatically simplified. Since no element connectivity data are needed, the burdensome remeshing required by the FEM is avoided. A growing crack can be modeled by simply extending the free surfaces, which correspond to the crack. In addition, stochastic meshless method (SMM) facilitates to have different discretizations for capturing the spatial variability of the material properties and the structural response, without much difficulty in mapping between the two discretizations. However, the computational cost of a SMM typically exceeds the cost of a SFEM. Hence, it is advantageous to adopt MLS approximation for material property discretization and FEM for structural response computation. This paper presents a new coupled finite element-moving least squares technique for predicting probabilistic structural response and reliability of cracked structures.
Alternate Repair Criteria for Primary Water Stress Corrosion Cracking
Authors: Fleck Jeffrey M. , Colgan Kent A.
Published: July 2008

PWSCC was identified in the early 1990’s within the roll expanded region near the primary tubesheet face in alloy 600 tubes of Once Through Steam Generators. Axial tube end cracks (TECs) located behind the tube-to-tubesheet roll expansion joint are of no structural concern, but nonetheless require repair per plant Technical Specifications. Therefore, there was a need to develop a method of permitting affected tubes to remain in-service. Framatome ANP completed an extensive program that was documented in a topical report and was approved by US NRC (1999) to allow these tubes to remain inservice by accounting for primary to secondary leakage under postulated MSLB conditions. Leakage is calculated following each tube inspection, must remain below site specific limits and is based on test results that applied simulated axial loads and tubesheet bow to a tube/tubesheet mockup and measured the resultant leakage though EDM notches. Testing demonstrated that joint tightness is the key parameter which correlates with leakage. Joint tightness is quantified via “delta dilation,” which depends upon axial tube load, tubesheet deformation, and primary side pressure. Test results were used with plant specific delta dilations to develop bounding leakage estimates for various regions of the tubesheet. The bounding leak rate was assigned to each identified TEC and all were summed to determine the total leak rate. Due to its deterministic nature, and its use of delta dilation values which do not reflect the difference between actual plant axial loads and those employed in the tests, this approach produces excessively conservative results. During recent inspections, the number of TECs has continued to increase and continued initiation is expected in both the hot and cold tube end regions. This, coupled with the conservatisms discussed above, led to increases in the number of tube repair rolls required to meet leakage limits. Consequently, the authors undertook an effort to reduce the conservatisms in the leakage determination process by accounting for the differences in tube loading conditions in the testing (Poisson effect) and by eliminating the deterministic leakage calculation approach. A Monte Carlo code (LeakTEC) was developed to perform the calculations in this manner. This new approach was recently approved by the NRC for use at one of the affected plants.
Application of Environmental Fatigue Penalty Factors and Implications for Design Analyses
Authors: Gray Mark A. , Cranford E. Lyles , Donavin Paul R.
Published: July 2008

A number of technical challenges have been identified in applying current methods to evaluate the effects of reactor water environment in fatigue evaluations of reactor components in license renewal applications. One challenge in using more conservative approaches is the large environmental penalty factor that may be calculated for stainless steels. The use of more sophisticated methods leads to more complex challenges, like the determination and application of transient strain rates required by the current proposed equations. For example, the definition of transients for component evaluations must consider competing effects of strain rate and stress range to assure a conservative design. As discussions extend to the possibility of addressing environmental effects in fatigue design requirements of the ASME Code, it is important to consider the implications of the challenges met in application of the current methods. This paper describes a plant-specific application of environmental fatigue penalty factors, the aspects of the challenges encountered in the application, and the ramifications of the various considerations on incorporation of fatigue environmental evaluations in future design requirements.
Enhancement of Thermoelectric Efficiency in PbTe by Distortion of the Electronic Density of States
Authors: Heremans Joseph P. , Jovovic Vladimir , Toberer Eric S. , Saramat Ali , Kurosaki Ken , Charoenphakdee Anek , Yamanaka Shinsuke , Snyder G. Jeffrey
Published: July 2008

The efficiency of thermoelectric energy converters is limited by the material thermoelectric figure of merit (
zT
). The recent advances in
zT
based on nanostructures limiting the phonon heat conduction is nearing a fundamental limit: The thermal conductivity cannot be reduced below the amorphous limit. We explored enhancing the Seebeck coefficient through a distortion of the electronic density of states and report a successful implementation through the use of the thallium impurity levels in lead telluride (PbTe). Such band structure engineering results in a doubling of
zT
in
p
-type PbTe to above 1.5 at 773 kelvin. Use of this new physical principle in conjunction with nanostructuring to lower the thermal conductivity could further enhance
zT
and enable more widespread use of thermoelectric systems.
Metronidazole Resistance in
Clostridium difficile
Is Heterogeneous
Authors: Peláez T. , Cercenado E. , Alcalá L. , Marín M. , Martín-López A. , Martínez-Alarcón J. , Catalán P. , Sánchez-Somolinos M. , Bouza E.
Published: July 2008

At our institution, the prevalence of clinical isolates of
Clostridium difficile
with resistance to metronidazole is 6.3%. We observed that initial metronidazole MICs of 16 to 64 mg/liter against toxigenic, primary fresh
C. difficile
isolates, as determined by agar dilution, decreased to 0.125 mg/liter after the isolates were thawed. In this study, we examined the possibility of heterogeneous or inducible resistance. Totals of 14 metronidazole-resistant and 10 metronidazole-susceptible clinical isolates of toxigenic
C. difficile
were studied. The isolates were investigated for the presence of
nim
genes by PCR. After the isolates were thawed, susceptibility testing was done by agar dilution, by disc diffusion using a 5-μg metronidazole disc, and by the Etest method. An experiment for determining the effect of prolonged exposure to metronidazole was applied to all resistant isolates and to susceptible control strains. None of the isolates presented the
nim
genes. All initially metronidazole-resistant
C. difficile
isolates became susceptible after thawing; however, they presented slow-growing subpopulations within the inhibition zones of both the disk and the Etest strip. All metronidazole-susceptible isolates remained homogeneously susceptible by both methods. After prolonged exposure in vitro to metronidazole, no zone of inhibition was found around the 5-μg disk in any of the metronidazole-resistant isolates, and the MICs as determined by the Etest method ranged from 0.125 to >256 mg/liter, with colonies growing inside the inhibition zone. Our results indicate that (i) resistance to metronidazole was not due to the presence of
nim
genes, (ii) resistance to metronidazole in toxigenic
C. difficile
isolates is heterogeneous, and (iii) prolonged exposure to metronidazole can select for in vitro resistance. We recommend routine performance of the disk diffusion method (5-μg metronidazole disk) with primary fresh
C. difficile
isolates in order to ensure that metronidazole-heteroresistant populations do not go undetected.
Diversity and abundance of ericoid mycorrhizal fungi of Gaultheria shallon on forest clearcuts
Authors: Xiao Guoping , Berch Shannon M.
Published: July 2008

Roots of salal (Gaultheria shallon Pursh) collected from forest clearcuts were examined by light and scanning electron microscopy, and the ericoid mycorrhizal fungi were isolated and identified. Heavy colonization of typical ericoid mycorrhizae was present in and restricted to the first of the two layers of root cortical cells. Neither ectomycorrhizae nor arbutoid mycorrhizae were observed. In the field, over 85% of the roots and 90% of the cortical cells within colonized roots were colonized. One hundred and seventy-five of the 278 fungal isolates from salal roots formed ericoid mycorrhizae with salal in the laboratory, and these isolates were grouped into four species based on spore formation and cultural characteristics: Oidiodendron griseum Robak, Acremonium strictwn W. Gams, and two unidentified, nonsporulating fungal species. The association in the laboratory between A. strictum and salal was atypical in that the fungus improved the growth of salal seedlings but was slow to colonize roots and occasionally grew and even sporulated on the shoots. No differences in percent colonization or diversity of ericoid mycorrhizal fungi were found in salal growing on clearcuts from two different forest types. Keywords: Gaultheria shallon, Oidiodendron griseum, Acremonium strictum, ericoid mycorrhizal fungi.
Camptothecin yield and distribution within Camptotheca acuminata trees cultivated in Louisiana
Authors: Liu Zhijun , Adams John
Published: July 2008

Camptotheca acuminata plantations were established in southern Louisiana in an effort to provide raw plant materials for deriving camptothecins, compounds having antitumor activity. This study was conducted to evaluate the growth and camptothecin distribution within the trees. It was found that all plant parts contained camptothecins following 1 year of growth in the field. Branches, roots, and stems accumulated significantly higher concentrations of camptothecins than leaves. Bark was significantly higher in camptothecin concentration than wood. Younger and older tissues within a growing season were not significantly different in camptothecin concentrations. High correlation in camptothecin concentration was found between branch and stem, root and stem, and root and branch, whereas little correlation was observed between bark and wood, and leaf and any other plant component. Field-grown C. acuminata has the observed characteristic of multiple current-year branching. The proportion of bark in term of dry weight and dimension decreased as trees increased in diameter. Dried shoots (bulk) contained 0.042% camptothecin, and dried roots (bulk) contained 0.051% camptothecin. Keywords: Camptotheca acuminata, medicinal plants cultivation, camptothecin content, camptothecin distribution, biomass.
The influence of light quality and carbon dioxide enrichment on the growth and physiology of seedlings of three conifer species. II. Physiological responses
Authors: Hoddinott John , Scott Rickey
Published: July 2008

Pinus banksiana, Picea mariana, and Picea glauca were grown at 350, 700, or 1050 μL∙L−1 CO2 and either high or low red/far-red quantum flux ratios. After a 16-week, long day growth period, seedlings were subjected sequentially to short daylengths, then short days with low temperatures. Various physiological parameters were determined at the end of each treatment phase to monitor how those treatments influenced the onset of seedling dormancy. After the long day treatments, high ratios increased the total chlorophyll content and reduced the original level of chlorophyll fluorescence and the shoot total nonstructural carbohydrate content in very shade-intolerant Pinus banksiana. In shade-tolerant Picea mariana, high CO2 levels caused the main effects on these parameters while neither light quality or CO2 had significant effects on them in shade-tolerant Picea glauca. Short days and low temperature induced a proportional increase in the partitioning of total nonstructural carbohydrate to the roots in all species and produced other species and treatment-specific responses. Keywords: light quality, CO2 enrichment, chlorophyll fluorescence.
Utilisation de la conductivité spécifique comme critère d'estimation de la viabilité au niveau de l'appareil aérien des vignes champenoises soumises aux températures négatives
Authors: Barka E. Aït , Audran J. C.
Published: July 2008

Specific conductivity is often used to determine plant freezing tolerance after a cold treatment. This study was undertaken to determine if there is a correlation between the evolution of aerial organs specific conductivity in vine (Vitis vinifera L.) and the extent of their viability with regard to the applied treatment. The data show two types of increases: the first one was observed along with the phenological evolution, in absence of any treatment, whereas the second appeared after the treatment on the organs. This increment was stronger at the bud than at the shoot level. Electrolyte leakage from the frost treated organs seems to be linked with their sensitivity to cold or the intensity of the applied treatment. Keywords: electrical conductivity, phenological stage, thermal stress, 2,3,5-triphenyltetrazolium chloride, Vitis vinifera L. [Journal translation]
Spatial patterns of modern diatom distribution and multiple paleolimnological records from a small arctic lake on Baffin Island, Arctic Canada
Authors: Wolfe Alexander P.
Published: July 2008

The assumption that within-lake, deep-water sedimentary diatom assemblages are relatively uniform and that a single core is sufficient to depict lake ontogeny was tested for a small tarn on the southwestern Cumberland Peninsula of Baffin Island, Northwest Territories. Diatom transport and deposition were evaluated through analyses of periphytic, planktonic, and epipelic habitats. Diatom stratigraphies of four cores were used to test whether or not trends are comparable in different regions of the lake and throughout the Holocene. Among 12 surface-sediment stations, diatom distributions were alternately highly equitable or variable. Valves of evenly distributed genera (Aulacoseira and Achnanthes) are mixed in the water column prior to deposition. This is supported by plankton tow and periphyton samples, which were respectively dominated by Aulacoseira distans (and varieties) and Achnanthes altaica. Conversely, frequencies of several benthic taxa (e.g., Pinnularia biceps, species of Eunotia) varied up to 30% between stations, in patterns unrelated to water depth, and reflecting habitat specificity and minimal transport prior to burial. Of the four cores (38.0–95.5 cm), analysis of the two longest revealed three distinct zones: (i) a zone dominated by species of Fragilaria (> 9000 BP); (ii) a zone containing benthic acidophilic diatoms indicating natural acidification (9000–7000 BP); and (iii) a zone characterized by numerous species of Aulacoseira ranging from the mid to late Holocene. Clear differentiation of the lower two zones was impossible in the shorter cores, and radiocarbon dates suggest that sediment reworking truncated the earliest records of organic sedimentation at these sites. Correspondence analysis facilitated comparisons of the diatom stratigraphies and enabled the evaluation of core reproducibility. Central cores preserve the most useful paleolimnological records in this environment. Keywords: diatoms, paleolimnology, Arctic Canada, Baffin Island.
Genetics ofCronartium ribicola. II. Variation in the ribosomal gene cluster
Authors: White E. E. , Foord B. M. , Kinloch Jr. B. B.
Published: July 2008

The ribosomal gene repeat in Cronartium ribicola J.C. Fisch is highly variable among spore samples from British Columbia, Canada. Both restriction site variation and length variation occur. Length heterogeneity results from differences in the number of subrepeats in the intergenic spacer (IGS). The number of IGS size classes in haploid cultures is limited but is very large and highly variable in aeciospores from single cankers. The proportions of different size classes vary among cankers on different trees, and among subsamples taken around the periphery of large old cankers. The results are consistent with the fungus having a haploid infective mycelium that produces functional pycnia that result in localized dikaryotic areas following fusion between flexuous hyphae and pycnia. Restriction site variation appears lower than has been reported in range-wide samples of endemic fungal species, consistent with the hypothesis that introduction of C. ribicola to western North America was limited and does not represent the full genetic range of the species. No particular restriction site variants or IGS size classes characterize samples from particular geographic areas. No evidence for geographic races of the fungus was obtained. Keywords: rusts, rust races, ribosomal DNA, intergenic spacer, population structure, RFLP.
Production et propriétés du complexe cellulasique du Botrytis cinerea
Authors: Touzani Abdellah , Donèche Bernard
Published: July 2008

The production of cellulasic complex by the fungal pathogen Botrytis cinerea is induced by addition of cellulose in the culture medium. The amount of activity increases greatly when the culture medium is supplemented with pectins, whereas glucose and cellobiose strongly inhibit the production of the complex. The cellulasic complex is constituted by three enzymes, separated and identified as β-glucosidase, exo 1,4-β-D-glucanase and endo 1,4-β-D-glucanase. The catalytic activity of the whole cellulasic complex is low and the inhibitors glucose and cellobiose act differently on this activity. Keywords: fungal pathogen, Botrytis cinerea, cellulasic complex, β-glucosidase, 1,4-β-D-glucanases.
Réponse des vignes champenoises aux températures negatives: effet d'un refroidissement contrôlé sur les réserves glucidiques du complexe gemmaire avant et au cours du débourrement
Authors: Barka E. Aït , Audran J. C.
Published: July 2008

Sugar concentrations were analyzed in grapevine (Vitis vinifera) buds at three different phenological stages (stage 1, dormant bud; stage 2, woolly bud; stage 5, green tip) and were submitted, under controlled conditions, to negative temperatures corresponding to the intracellular liquid crystallization points. In absence of any treatment, starch concentration diminished according to the phenological evolution, indicating its utilization during bud breaking. Starch and raffinose accumulated when controlled cooling was applied, except for stage 1 buds collected on March 6, 1993. Similarly, saccharose concentrations were reduced in bud complexes after temperature reductions. Fructose and glucose concentrations seemed to be less sensitive to thermal variations. The accumulation of starch observed at the end of a cold treatment could be partly explained by the inhibition of amylase activity under cold conditions. Keywords: bud, Vitis vinifera L., phenological stage, thermal stress, sugars. [Journal translation]
Cardiovascular drift in euhydrated prepubertal boys
Authors: Rowland Thomas , Pober David , Garrison Anne
Published: July 2008

“Classic” cardiovascular drift is characterized by findings of decreasing stroke volume and mean arterial pressure, rising heart rate, and stable cardiac output during sustained constant-load exercise. Recent studies in adults indicate that when dehydration is prevented by fluid intake, this pattern is altered, with no change in stroke volume and progressive rise in cardiac output. This study was designed to examine this influence of hydration in prepubertal subjects and assess the relationship between cardiovascular drift and aerobic drift (changes in VO2). Eight boys (Tanner stage 1, mean age 11.7 ± 0.4 y) cycled at an average of 62.9% ± 3.9% VO2 peak to exhaustion (41.38 ± 6.30 min) in a thermoneutral environment. Rectal temperature rose from 37.6 ± 0.1 °C at rest to 38.1 ± 0.2 °C at end exercise. Between 5 min and end exercise, average heart rate rose by 13.2% and cardiac output rose by 14.9%, systemic vascular resistance fell by 10.5%, and stroke volume remained stable. Increases in cardiac output paralleled those of VO2, with no change in arterial venous oxygen difference. These findings are consistent with the conclusion that cardiovascular drift is a reflection of aerobic drift, a relationship obscured by the superimposed physiological effects of dehydration during sustained constant load. This study also suggests that such patterns are no different in prepubertal boys and young adult men.
Comparative analysis of skeletal muscle oxidative capacity in children and adults: a 31P-MRS study
Authors: Ratel Sébastien , Tonson Anne , Le Fur Yann , Cozzone Patrick , Bendahan David
Published: July 2008

The aim of the present study was to compare the oxidative capacity of the forearm flexor muscles in vivo between children and adults using 31-phosphorus magnetic resonance spectroscopy. Seven boys (11.7 ± 0.6 y) and 10 men (35.6 ± 7.8 year) volunteered to perform a 3 min dynamic finger flexions exercise against a standardized weight (15% of the maximal voluntary contraction). Muscle oxidative capacity was quantified on the basis of phosphocreatine (PCr) post-exercise recovery kinetics analysis. End-of-exercise pH was not significantly different between children and adults (6.6 ± 0.2 vs. 6.5 ± 0.2), indicating that indices of PCr recovery kinetics can be reliably compared. The rate constant of PCr recovery (kPCr) and the maximum rate of aerobic ATP production were about 2-fold higher in young boys than in men (kPCr: 1.7 ± 1.2 vs. 0.7 ± 0.2 min–1; Vmax: 49.7 ± 24.6 vs. 29.4 ± 7.9 mmol·L–1·min–1, p < 0.05). Our results clearly illustrate a greater mitochondrial oxidative capacity in the forearm flexor muscles of young children. This larger ATP regeneration capacity through aerobic mechanisms in children could be one of the factors accounting for their greater resistance to fatigue during high-intensity intermittent exercise.
Physical activity of Canadian and American children: a focus on youth in Amish, Mennonite, and modern cultures
Authors: Bassett David R.
Published: July 2008

Childhood obesity is an urgent public health problem in North America and throughout most of the industrialized world. Diminishing levels of physical activity and the growth of sedentary pursuits may be contributing to the obesity epidemic. The advent of modern technological societies has brought about dramatic changes in lifestyle over the past century. To gain insights into physical activity levels in pre-industrial era societies, researchers have turned to studying religious groups that have resisted the lure of technological change. Children in Old Order Amish and Old Order Mennonite communities of North America have a lifestyle that still involves walking to school and friends' homes, performing chores, caring for farm animals, and active play. Research has shown that Amish and Mennonite children have higher levels of physical activity than modern-living children, despite less participation in organized competitive sports. As a result, Amish and Mennonite children tend to be leaner than their counterparts in contemporary society. Studying non-mainstream cultures can provide a valuable perspective on human behaviors.
The influence of sex, menstrual cycle phase, estrogen, obesity, and endurance training on carbohydrate and lipid metabolism at rest and during moderate-intensity endurance exercise
Authors: Devries Michaela C.
Published: July 2008

Carbohydrate (CHO) and fat constitute the main fuels used during endurance exercise. The purpose of this thesis was to determine how sex, menstrual cycle phase, estrogen, obesity, and endurance training (ET) influence substrate metabolism. In study 1, men (n = 11) and women (n = 13) underwent primed constant infusion of [6,6-2H] glucose with muscle biopsies taken before and after a 90 min bike ride at 65% VO2 peak. Luteal-phase women had lower muscle glycogen utilization compared with follicular-phase women. Women had lower respiratory exchange ratio (RER) and plasma glucose utilization than men. In study 2, men (n = 17) and women (n = 19) had muscle biopsies taken before and after a 90 min bike ride at 65% VO2 peak. Women had greater intramyocellular lipid (IMCL) content and lower RER during exercise, with no effect of sex on net IMCL utilization. In study 3, Men (n = 11) were treated with 17-β-estradiol (E2, 2 mg·d–1, 8 d) and placebo and underwent primed constant infusion of [6,6–2H] glucose with muscle biopsies taken before and after a 90 min bike ride at 65% VO2 peak. E2 lowered RER and plasma glucose oxidation during exercise, with no effect on muscle glycogen utilization. In study 4, lean (n = 12) and obese (n = 11) women underwent 12 weeks of ET with muscle biopsies taken before and after training. Obese women were insulin resistant compared with lean women. ET increased oxidative capacity and β-oxidation capacity, as well as mitochondrial content. ET redistributed IMCL from the subsarcolemmal region to the intermyofibrillar region of the muscle fibre. These studies demonstrate that substrate metabolism is affected by many factors in health and disease and the ability to manipulate these factors is of importance to athletes wishing to improve performance, as well as to obese individuals attempting to normalize an altered metabolic state.
Influence de l'exercice physique pendant et après la plongée sur le risque d’accident de décompression
Authors: Gempp Emmanuel , Blatteau Jean-Éric
Published: July 2008

Exercise at depth and during decompression is a commonly accepted factor that affects the risk of decompression sickness in divers and aviators, but data documenting these effects are limited and conflicting. The mechanisms may be complex and influenced by several factors, such as the type and nature of exercise, the temporal course of the exercise in relation to the decompression procedure, and the diving profile. This paper reviews previous studies in this field of research, and discusses current concepts in diving activities.
Exercise and the fatty liver
Authors: Spassiani Natasha A. , Kuk Jennifer L.
Published: July 2008

Fatty liver is an increasingly prevalent condition that is associated with several metabolic derangements, thus necessitating the development of effective therapeutic interventions. Growing evidence from cross-sectional studies suggest that physical activity may be a promising therapy for fatty liver. Unfortunately, longitudinal evidence supporting this observation in humans is sparse, as the majority of intervention studies have examined the relationship between liver fat and physical activity in conjunction with caloric and dietary fat restriction. Studies in rats demonstrate a beneficial effect of exercise on liver fat, mainly in situations of high fat feeding or obesity. Thus, the independent contribution of physical activity on variations in liver fat is unknown, but remains a promising intervention that requires further investigation. There is some evidence to suggest that both physical activity and liver fat are independent correlates of cardiovascular and type 2 diabetes risk. The relative contribution of each remains unclear, but implies that both should be considered when developing therapeutic interventions for chronic metabolic disease.