bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating groundwater exchange with lakes: 2. Calibration of a three‐dimensional, solute transport model to a stable isotope plume
Authors: Krabbenhoft David P. , Anderson Mary P. , Bowser Carl J.
Published: February 2008

A three‐dimensional groundwater flow and solute transport model was calibrated to a plume of water described by measurements of δ18O and used to calculate groundwater inflow and outflow rates at a lake in northern Wisconsin. The flow model was calibrated to observed hydraulic gradients and estimated recharge rates. Calibration of the solute transport submodel to the configuration of a stable isotope (18O) plume in the contiguous aquifer on the downgradient side of the lake provides additional data to constrain the model. A good match between observed and simulated temporal variations in plume configuration indicates that the model closely simulated the dynamics of the real system. The model provides information on natural variations of rates of groundwater inflow, lake water outflow, and recharge to the water table. Inflow and outflow estimates compare favorably with estimates derived by the isotope mass balance method (Krabbenhoft et al., this issue). Model simulations agree with field observations that show groundwater inflow rates are more sensitive to seasonal variations in recharge than outflow.
Immobile water during solute transport in unsaturated sand columns
Authors: Bond W. J. , Wierenga P. J.
Published: February 2008

Solute transport experiments were carried out to investigate the presence of immobile water in an unsaturated fine sand under different flow regimes. Both steady and unsteady flow conditions were imposed, but the average pore water velocity and water content were the same in each. Evidence for the presence of an immobile water fraction was sought by fitting the concentration distributions using models both with and without an explicit term accounting for solute exchange with immobile water. Strong evidence was found for the presence of an immobile water fraction affecting the solute concentration distribution under steady flow conditions but not for unsteady flow. These apparently conflicting results are explained in terms of different water flow patterns arising from the two flow regimes.
Application of the Arnoldi Algorithm to the solution of the advection‐dispersion equation
Authors: Woodbury Allan D. , Dunbar W. Scott , Nour‐Omid Bahram
Published: February 2008

The solution to the finite element matrix differential equations resulting from the discretization of the contaminant transport equation is normally carried out by a finite difference approximation to the time derivative. The total computational effort in simulating a contaminant plume is then directly related to the number of unknowns and the number of time steps required to obtain accurate and stable solutions. An alternative method is the Arnoldi algorithm which uses orthogonal matrix transformations to reduce the finite element equations to a much smaller upper Hessenberg system of first‐order differential equations. This new system can be solved by a standard Crank‐Nicolson algorithm with very little computational effort. A matrix‐vector multiplication is then used to obtain the original solution at desired time steps. The algorithm is used to simulate accurately the contaminant plumes for a strip source areal aquifer, a cross‐sectional problem, and the Borden landfill in Ontario, Canada. The Arnoldi algorithm shows an impressive 613% increase in speed over the conventional Crank‐Nicolson scheme for this latter case. The method affords an efficient means of solving large problems, particularly when time durations are long.
Experimental and theoretical study of temperature dependent exciton delocalization and relaxation in anthracene thin films
Authors: Ahn Tai-Sang , Müller Astrid M. , Al-Kaysi Rabih O. , Spano Frank C. , Norton Joseph E. , Beljonne David , Brédas Jean-Luc , Bardeen Christopher J.
Published: February 2008

The spectroscopy of solid anthracene is examined both experimentally and theoretically. To avoid experimental complications such as self-absorption and polariton effects, ultrathin polycrystalline films deposited on transparent substrates are studied. To separate the contributions from different emitting species, the emission is resolved in both time and wavelength. The spectroscopic data are interpreted in terms of a three-state kinetic model, where two excited states, a high energy state 1 and a low energy state 2, both contribute to the luminescence and are kinetically coupled. Using this model, we analyze the spectral lineshape, relative quantum yield, and relaxation rates as a function of temperature. For state 1, we find that the ratio of the 0-0 vibronic peak to the 0-1 peak is enhanced by roughly a factor of 3.5 at low temperature, while the quantum yield and decay rates also increase by a similar factor. These observations are explained using a theoretical model previously developed for herringbone polyacene crystals. The early-time emission lineshape is consistent with that expected for a linear aggregate corresponding to an edge-dislocation defect. The results of experiment and theory are quantitatively compared at different temperatures in order to estimate that the singlet exciton in our polycrystalline films is delocalized over about ten molecules. Within these domains, the exciton’s coherence length steadily increases as the temperature drops, until it reaches the limits of the domain, whereupon it saturates and remains constant as the temperature is lowered further. While the theoretical modeling correctly reproduces the temperature dependence of the fluorescence spectral lineshape, the decay of the singlet exciton appears to be determined by a trapping process that becomes more rapid as the temperature is lowered. This more rapid decay is consistent with accelerated trapping due to increased delocalization of the exciton at lower temperatures. These observations suggest that exciton coherence can play an important role in both radiative and nonradiative decay channels in these materials. Our results show that the spectroscopy of polyacene solids can be analyzed in a self-consistent fashion to obtain information about electronic delocalization and domain sizes.
Thermoelectric power in carbon nanotubes and quantum wires of nonlinear optical, optoelectronic, and related materials under strong magnetic field: Simplified theory and relative comparison
Authors: Ghatak K. P. , Bhattacharya S. , Bhowmik S. , Benedictus R. , Choudhury S.
Published: February 2008

We study thermoelectric power under strong magnetic field (TPM) in carbon nanotubes (CNTs) and quantum wires (QWs) of nonlinear optical, optoelectronic, and related materials. The corresponding results for QWs of III-V, ternary, and quaternary compounds form a special case of our generalized analysis. The TPM has also been investigated in QWs of II-VI, IV-VI, stressed materials, n-GaP, p-PtSb2, n-GaSb, and bismuth on the basis of the appropriate carrier dispersion laws in the respective cases. It has been found, taking QWs of n-CdGeAs2, n-Cd3As2, n-InAs, n-InSb, n-GaAs, n-Hg1−xCdxTe, n-In1−xGaxAsyP1−y lattice-matched to InP, p-CdS, n-PbTe, n-PbSnTe, n-Pb1−xSnxSe, stressed n-InSb, n-GaP, p-PtSb2, n-GaSb, and bismuth as examples, that the respective TPM in the QWs of the aforementioned materials exhibits increasing quantum steps with the decreasing electron statistics with different numerical values, and the nature of the variations are totally band-structure-dependent. In CNTs, the TPM exhibits periodic oscillations with decreasing amplitudes for increasing electron statistics, and its nature is radically different as compared with the corresponding TPM of QWs since they depend exclusively on the respective band structures emphasizing the different signatures of the two entirely different one-dimensional nanostructured systems in various cases. The well-known expression of the TPM for wide gap materials has been obtained as a special case under certain limiting conditions, and this compatibility is an indirect test for our generalized formalism. In addition, we have suggested the experimental methods of determining the Einstein relation for the diffusivity-mobility ratio and the carrier contribution to the elastic constants for materials having arbitrary dispersion laws.
C–H bond activation over metal oxides: A new insight into the dissociation kinetics from density functional theory
Authors: Li Hui-Ying , Guo Yang-Long , Guo Yun , Lu Guan-Zhong , Hu P.
Published: February 2008

The C–H activation on metal oxides is a fundamental process in chemistry. In this paper, we report a density functional theory study on the process of the C–H activation of CH4 on Pd(111), Pt(111), Ru(0001), Tc(0001), Cu(111), PdO(001), PdO(110), and PdO(100). A linear relationship between the C–H activation barrier and the chemisorption in the dissociation final state on the metal surfaces is obtained, which is consistent with the work in the literature. However, the relationship is poor on the metal oxide surfaces. Instead, a strong linear correlation between the barrier and the lattice O–H bond strength is found on the oxides. The new linear relationship is analyzed and the physical origin is identified.
Independent Processing of Form, Colour, and Texture in Object Perception
Authors: Cant Jonathan S , Large Mary-Ellen , McCall Lindsay , Goodale Melvyn A
Published: February 2008

Most investigations of object recognition have focused on the form rather than the material properties of objects. Nevertheless, knowledge of the material properties of an object (via its surface cues) can provide important information about that object's identity. In this study, we used Garner's speeded-classification task to explore whether or not the processing of form and the processing of surface properties are independent. In experiment 1, participants made length and width classifications in an initial form task. Participants were unable to ignore length while making width classifications, and were unable to ignore width while making length classifications. This suggests that the perception of length and the perception of width share common processing resources. In a subsequent task, we examined possible interactions between the processing of form and the processing of surface properties. In contrast to the findings with the form task, participants were able to ignore form while making surface-property classifications, and to ignore surface properties while making form classifications. This suggests that the form of objects and their surface properties are processed independently. In experiment 2, we went on to show that the two prominent surface-property dimensions of colour and texture can also be processed independently. In other words, participants were able to ignore colour while making texture classifications, and vice versa. Finally, in experiment 3, we examined the possibility that the stimuli and required responses that we used in experiment 2 were too categorical and thus not optimal for assessing whether or not colour and texture share common processing resources. Using a different stimulus set, participants were again able to ignore colour while making texture classifications, and vice versa. Taken together, these results provided convincing evidence that the separate ventral-stream brain regions identified for form, texture, and colour in a recent neuroimaging study (Cant and Goodale, 2007 Cerebral Cortex17 713–731) can indeed function independently.
Effect of the glycaemic index of pre‐exercise carbohydrate meals on running performance
Authors: Wong Stephen H. S. , Siu Parco M. , Lok Andy , Chen Y. J. , Morris John , Lam C. W.
Published: February 2008

The aim of this study was to examine the effect of pre‐exercise low and high glycaemic index (GI) carbohydrate meals on running performance. Eight endurance‐trained male runners (mean age 33 years, s x =1.7; 63 ml · kg−1 · min−1, s x =1.8) completed two trials separated by at least 7 days in a counterbalanced design. Two hours before they were to run and after an overnight fast, each participant consumed an isocaloric meal containing either low (gi=37) or high (gi=77) GI carbohydrate foods (2.4 MJ; 65% carbohydrate; 15% protein; 20% fat) that provided 1.5 g carbohydrate per kilogram of body mass in random order. Each trial consisted of a 21‐km performance run on a level treadmill. The participants were required to run at 70% during the first 5 km of the run. They subsequently completed the remaining 16 km in as short a time as possible. All participants achieved a faster performance time after the consumption of the low GI meal (low vs. high GI: 98.7 min, s x =2 vs. 101.5 min, s x =2; P<0.01). Blood glucose and serum free fatty acids concentrations were higher throughout the performance run in the low GI trial. Serum insulin concentrations were higher in the high GI trial during the postpandial resting period. However, there were no differences between trials in serum insulin or blood lactate concentrations throughout exercise. Compared with the high GI trial, carbohydrate oxidation was 9.5% lower and fat oxidation was 17.9% higher during exercise in the low GI trial. In conclusion, our results indicate that compared with an isocaloric high GI meal, the consumption of a low GI meal 2 h before a 21‐km performance run is a more effective means of improving performance time.
ITALICS: an algorithm for normalization and DNA copy number calling for Affymetrix SNP arrays
Authors: Rigaill Guillem , Hupé Philippe , Almeida Anna , La Rosa Philippe , Meyniel Jean-Philippe , Decraene Charles , Barillot Emmanuel
Published: February 2008

Motivation: Affymetrix SNP arrays can be used to determine the DNA copy number measurement of 11 000–500 000 SNPs along the genome. Their high density facilitates the precise localization of genomic alterations and makes them a powerful tool for studies of cancers and copy number polymorphism. Like other microarray technologies it is influenced by non-relevant sources of variation, requiring correction. Moreover, the amplitude of variation induced by non-relevant effects is similar or greater than the biologically relevant effect (i.e. true copy number), making it difficult to estimate non-relevant effects accurately without including the biologically relevant effect.

Results: We addressed this problem by developing ITALICS, a normalization method that estimates both biological and non-relevant effects in an alternate, iterative manner, accurately eliminating irrelevant effects. We compared our normalization method with other existing and available methods, and found that ITALICS outperformed these methods for several in-house datasets and one public dataset. These results were validated biologically by quantitative PCR.

Availability: The R package ITALICS (ITerative and Alternative normaLIzation and Copy number calling for affymetrix Snp arrays) has been submitted to Bioconductor.

Contact:  italics@curie.fr

Supplementary information: Supplementary data are available at Bioinformatics online.
A constructive empirical theory for metal fatigue under block cyclic loading
Authors: Patil Navendu , Mahadevan Pradeep , Chatterjee Anindya
Published: February 2008

Much modern engineering design work usesS–Ncurves and empirical applications thereof. In industry, currently popular methods for predicting fatigue life under complex loading use ad hoc cycle counting algorithms along with Miner's rule, in spite of its known weaknesses. Many ad hoc alternatives to Miner's rule have been proposed, each with limited experimental justification. Of these, Manson's double linear damage rule (DLDR) is widely considered to be good. In this paper, we bring a new perspective to empirical, as opposed to mechanistic, fatigue damage evolution models. It is first assumed, with reasonable justification, that there is a scalar, abstract, damage variableϕ, whose evolution under cyclic loading satisfies, whereaandmare unknown functions of load parameters. One main contribution of the paper lies in deducing what the functionsaandmmust be in order to obtain consistency with fatigue data in handbooks. A small correction to this basic power law model is then developed. The final explicit model initially has 10 unknown fitted parameters, but these are brought down to three unknowns; the accompanying discussion is the other main contribution of the paper. Finally, comparison with Manson's and other data suggests that, with two fitted parameters, our model works as well as the DLDR and much better than Miner's rule. For other parameter choices, our model reduces to Miner's rule. We conclude with speculation about ways in which the model might be extended beyond the scope of the DLDR.
On the impulsive generation of drops at the interface of two inviscid fluids
Authors: Tjan K.K , Phillips W.R.C
Published: February 2008

The numerical simulation of the deformation of an inviscid fluid–fluid interface subjected to an axisymmetric impulse in pressure is considered. Using a boundary integral formulation, the interface is evolved for a range of upper-fluid and lower-fluid density ratios under the influence of inertial, interfacial and gravitational forces. The interface is seen to evolve into axisymmetric waves or droplets depending upon the density ratio, level of surface tension and gravity. Moreover, the droplets may be spherical, tear shaped or elongated. These conclusions are expressed in a phase diagram of inverse Weber number
We
−1
versus Atwood number
At
at zero gravity, i.e. with the Froude number
Fr
−1
→0, and complement the earlier findings of Tjan & Phillips, who present a phase diagram of
We
−1
versus
Fr
−1
for the case in which the upper fluid has zero density. They too report tear-shaped droplets; however, while, in their paper, they form as a result of gravity, those reported here form as a result of surface tension. It is also found that the pinch-off process which effects drops remains of the power-law type with exponent 2/3 irrespective of the presence of gravity and an upper fluid. However, the constant

that relates the necking radius to the time from pinch off, which is universal in the absence of gravity and an upper fluid, is affected by the presence gravity, an upper fluid and the class of drops which form.
Human oestrus
Authors: Gangestad Steven W , Thornhill Randy
Published: February 2008

For several decades, scholars of human sexuality have almost uniformly assumed that women evolutionarily lost oestrus—a phase of female sexuality occurring near ovulation and distinct from other phases of the ovarian cycle in terms of female sexual motivations and attractivity. In fact, we argue, this long-standing assumption is wrong. We review evidence that women's fertile-phase sexuality differs in a variety of ways from their sexuality during infertile phases of their cycles. In particular, when fertile in their cycles, women are particularly sexually attracted to a variety of features that likely are (or, ancestrally, were) indicators of genetic quality. As women's fertile-phase sexuality shares with other vertebrate females' fertile-phase sexuality a variety of functional and physiological features, we propose that the term oestrus appropriately applies to this phase in women. We discuss the function of women's non-fertile or extended sexuality and, based on empirical findings, suggest ways that fertile-phase sexuality in women has been shaped to partly function in the context of extra-pair mating. Men are particularly attracted to some features of fertile-phase women, but probably based on by-products of physiological changes males have been selected to detect, not because women signal their cycle-based fertility status.
In vitro
digestibility of fern and gymnosperm foliage: implications for sauropod feeding ecology and diet selection
Authors: Hummel Jürgen , Gee Carole T , Südekum Karl-Heinz , Sander P. Martin , Nogge Gunther , Clauss Marcus
Published: February 2008

Sauropod dinosaurs, the dominant herbivores throughout the Jurassic, challenge general rules of large vertebrate herbivory. With body weights surpassing those of any other megaherbivore, they relied almost exclusively on pre-angiosperm plants such as gymnosperms, ferns and fern allies as food sources, plant groups that are generally believed to be of very low nutritional quality. However, the nutritive value of these taxa is virtually unknown, despite their importance in the reconstruction of the ecology of Mesozoic herbivores. Using a feed evaluation test for extant herbivores, we show that the energy content of horsetails and of certain conifers and ferns is at a level comparable to extant browse. Based on our experimental results, plants such as
Equisetum
,
Araucaria
,
Ginkgo
and
Angiopteris
would have formed a major part of sauropod diets, while cycads, tree ferns and podocarp conifers would have been poor sources of energy. Energy-rich but slow-fermenting
Araucaria
, which was globally distributed in the Jurassic, was probably targeted by giant, high-browsing sauropods with their presumably very long ingesta retention times. Our data make possible a more realistic calculation of the daily food intake of an individual sauropod and improve our understanding of how large herbivorous dinosaurs could have flourished in pre-angiosperm ecosystems.
Physiological effects in juvenile three‐spined sticklebacks feeding on toxic cyanobacterium Nodularia spumigena‐exposed zooplankton
Authors: Pääkkönen J.‐P. , Rönkkönen S. , Karjalainen M. , Viitasalo M.
Published: February 2008

Feeding rate, growth and nutritional condition as well as nodularin concentration of juvenile three‐spined sticklebacks Gasterosteus aculeatus were assessed in an experimental study where field‐collected fish were given a diet of zooplankton fed with toxic Nodularia spumigena for 15 days. Food consumption was higher in N. spumigena bloom conditions compared with the cyanobacterium‐free control, but despite this the growth rate of exposed fish did not improve. Control fish and fish fed N. spumigena‐exposed zooplankton had higher RNA:DNA ratios and protein content than fish grown in cyanobacterial bloom conditions indicating good nutritional condition and recent growth of fish, whereas in bloom conditions metabolic transformation of nodularin to less toxic compounds may cause an energetic cost to the fish affecting the growth rate of the whole organism. Juvenile three‐spined sticklebacks collected from the field contained higher concentrations of nodularin at the beginning of the experiment (mean 503·1 μg kg−1). After 15 days, the lowest nodularin concentrations in fish were measured in the control treatment, suggesting that fish fed with non‐toxic food are able to detoxify nodularin from their tissues more effectively than fish in continuing exposure.
What can metazoan parasites reveal about the taxonomy of Scomber japonicus Houttuyn in the coast of South America and Madeira Islands?
Authors: Oliva M. E. , Valdivia I. M. , Costa G. , Freitas N. , Pinheiro De Carvalho M. A. , Sánchez L. , Luque J. L.
Published: February 2008

The metazoan parasites of four populations of the chub mackerel Scomber japonicus were analysed from two localities in the Atlantic Ocean (Madeira Islands, Portugal, and Rio de Janeiro, Brazil) and two localities in the Pacific Ocean (Callao, Peru, and Antofagasta, Chile), collected during 2002 and 2003. A total of 373 fish specimens were studied and 34 metazoan parasite species were obtained. Parasites identified from the populations of chub mackerel studied could be separated into three categories: parasites with a wide distribution, present in the Pacific and Atlantic, parasites proper of the Pacific Ocean and parasites proper of the Atlantic Ocean. The analyses of some highly specific parasites of the genus Scomber (i.e. monogeneans of the genus Kuhnia and didymozoid digeneans) strongly suggest the need for a revision of the taxonomic status of chub mackerels from the Atlantic and Pacific coast of America. The results demonstrated the usefulness of parasites as adequate tools to clarify the taxonomic status of their hosts.
Gait transition speed as an alternate measure of maximum aerobic capacity in fishes
Authors: Peake S. J.
Published: February 2008

This study demonstrated that the transition from a steady to an unsteady locomotory gait (USTmax) in juvenile brook trout Salvelinus fontinalis can be measured easily using a new tilting raceway design and a simple experimental protocol. It was found that USTmax increased linearly with fork length (LF), and that this relationship was statistically identical in fish that swam volitionally in the raceway and those that were forced to perform, although slightly different data processing methods were needed in the latter to achieve this result. Furthermore, the relationship between LF and USTmax was statistically identical to that between LF and critical swimming speed (Ucrit), although LF in the former relationship explained 83% of the variance compared to 37% in the latter. This finding indicates that gait transition speed can be used to estimate maximum aerobic capacity, with less unexplainable variance than Ucrit. Gait transition speeds were also determined from Ucrit tests; however, this required measuring and incorporating ground speed into the analysis. USTmax as determined in the Ucrit tests was not significantly different from that measured in the raceway, suggesting that gait transition speed can be measured in raceways or swim tunnel respirometers.
Novel application of multicellular layers culture forin situevaluation of cytotoxicity and penetration of paclitaxel
Authors: Al‐Abd Ahmed Mohamed , Lee Joo‐Ho , Kim So Yeon , Kun Na , Kuh Hyo‐Jeong
Published: February 2008

Limited drug penetration into tumor tissue is one of the major factors causing clinical drug resistance in human solid tumors. The multicellular layers (MCL) of human cancer cells have been successfully used to study tissue pharmacokinetics of anticancer drugs. The purpose of this study was to develop a direct and simple method to evaluate vitality changesin situwithin MCL using calcein‐AM. Human colorectal (DLD‐1, HT‐29) and bladder (HT‐1376, J‐82) cancer cells were grown in Transwell inserts to form MCL and subjected to paclitaxel exposure. The drug distribution was evaluated using paclitaxel‐rhodamine. Photonic attenuation and limited penetration of calcein‐AM prevented cellular vitality evaluation on optical sections under confocal microscopy in DLD‐1 MCL. However, direct measurement of the fluorescence intensity on frozen sections of MCL allowed successful vitality assessment in more than 80% depth for HT‐29 and J‐82 MCL and in the upper 40% depth for DLD‐1 and HT‐1376 MCL. The penetration of paclitaxel‐rhodamine was greater in HT‐29 than DLD‐1 and its distribution pattern was correlated to the spatial profile of vitality deterioration in both MCL, suggesting that tissue penetration may be an important determinant of drug effect in tumors. In conclusion, a novel method for vitality evaluationin situwithin MCL was developed using calcein‐AM. This method may provide clinically relevant data regarding the spatial pharmacodynamics of anticancer agents within avascular regions of solid tumors. (Cancer Sci2008; 99: 423–431)
Aberrant splicing and protease involvement in mesothelin release from epithelioid mesothelioma cells
Authors: Sapede Carole , Gauvrit Anne , Barbieux Isabelle , Padieu Martine , Cellerin Laurent , Sagan Christine , Scherpereel Arnaud , Dabouis Gérard , Grégoire Marc
Published: February 2008

Elevated amounts of soluble mesothelin‐related proteins (SMRP) have already been reported in sera and pleural effusions from mesothelioma patients, providing a useful diagnostic marker for malignant pleural mesothelioma (MPM). However, the origin of SMRP is not yet understood. Production of SMRP could be related to abnormal splicing events leading to synthesis of a secreted protein (release) or to an enzymatic cleavage from membrane‐bound mesothelin (ectodomain shedding). To test these hypotheses, we used a panel of mesothelioma cells established in culture from pleural effusions of MPM patients. Our in vitro results confirmed specific mesothelin expression and SMRP production in supernatants from epithelioid MPM cell lines, thus providing a relevant cellular model to study soluble mesothelin production mechanisms. The expression of mesothelin‐encoding RNA variants was screened by reverse transcription–polymerase chain reaction experiments. Protease involvement in mesothelin cleavage from the cellular surface was investigated by treatment of MPM cells with GM6001, a broad‐spectrum MMP‐ and ADAM‐family inhibitor. GM6001 treatment significantly impaired SMRP production by MPM cell lines, in favor of an enzymatic‐mediated shedding process. In addition, a splice variant transcript of mesothelin (variant 3) was detected in these MPM cell lines, in accordance with the release of a secreted part of the protein. Our results indicate that both mechanisms could be implicated in soluble mesothelin production by epithelioid mesothelioma cells. (Cancer Sci 2008; 99: 590–594)
Suppression of anoikis by the neurotrophic receptor TrkB in human ovarian cancer
Authors: Yu Xiaohui , Liu Ling , Cai Bin , He Yinyan , Wan Xiaoping
Published: February 2008

TrkB is a neurotrophic tyrosine kinase receptor (Trk). To investigate its role in anoikis suppression in human ovarian cancer, we used reverse transcription–polymerase chain reaction and real‐time polymerase chain reaction, immunohistochemistry, and western blotting to compare the expression levels of TrkB and its ligand brain‐derived neurotrophic factor between (i) 20 epithelial ovarian cancers, their multicellular spheroids in ascites or great omentum metastatic lesions, and eight borderline or benign ovarian tumors, as well as four normal ovarian tissues; and (ii) three ovarian cancer cell lines cultured under different conditions: monolayer adhesive culture (adhesive cells), anchorage‐independent culture (cell spheroids), and trypsinized cell spheroids placed in monolayer adhesive dishes (cell spheroids replaced). TrkB and brain‐derived neurotrophic factor were overexpressed in epithelial ovarian cancers, and full‐length TrkB was more often overexpressed in high‐grade carcinomas and multicellular spheroids in ascites. Expression of TrkB mRNA was higher in OVCAR‐3 cell spheroids than in adhesive cells. The expression of full‐length TrkB protein was highest in OVCAR‐3 cell spheroids, but its precursor was expressed highly in OVCAR‐3 cells under all three culture conditions. The relationship between TrkB overexpression and phosphatidylinositol 3′‐kinase (PI3K)–AKT pathway activation in OVCAR‐3 cells was studied by western blotting and RNA interference. The PI3K–AKT pathway was highly activated in anoikis‐survived cells and was inhibited when TrkB was silenced by small interfering RNA. Finally, the chemosensitivity and invasiveness of OVCAR‐3 cells were examined by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium, fluorescence‐activated cell sorting, Matrigel invasion assay, and in vivo studies. Adhesive cells showed higher chemosensitivity and lower invasion ability than anoikis‐survived cells. Our study suggests that TrkB might mediate anoikis suppression by activating the PI3K–AKT pathway in ovarian cancer cells. (Cancer Sci 2008; 99: 543–552)
The genetics of nicotine addiction liability: ethical and social policy implications
Authors: Hall Wayne D. , Gartner Coral E. , Carter Adrian
Published: February 2008

Aim  To assess the promise and risks of technological applications of genetic research on liability to develop nicotine dependence.

Methods  We reviewed (i) the evidence on the genetics of nicotine dependence; (ii) the technical feasibility of using genetic information to reduce smoking uptake and increase cessation; and (iii) policy and ethical issues raised by the uses of genetic information on addiction liability.

Results  (i) Despite evidence from twin studies that genes contribute to addiction susceptibility, research to date has not identified commonly occurring alleles that are strongly predictive of developing nicotine addiction. Nicotine addiction is likely to involve multiple alleles of small effect that interact with each other and with the environment. (ii) Population screening for susceptibility alleles is unlikely to be effective or cost‐effective. Tailoring of smoking cessation treatments with genetic information is more plausible but results to date have been disappointing. Population health strategies such as increased taxation and reduced opportunities to smoke are more efficient in reducing cigarette smoking. Tobacco harm reduction policies applied to populations may also play a role in reducing tobacco‐related harm. (iii) Future uses of genomic information on addiction risk will need to assess the risks of medicalising addiction (e.g. pessimism about capacity to quit) and community concerns about genetic privacy.

Conclusions  Nicotine genomics is a very new and underdeveloped field. On the evidence to date, its advocates would be wise to avoid extravagant claims about its preventive applications.
Estimation of dose requirements for sustainedin vivoactivity of a therapeutic human anti‐CD20 antibody
Authors: Bleeker Wim K. , Munk Martin E. , Mackus Wendy J. M. , Van Den Brakel Jeroen H. N. , Pluyter Marielle , Glennie Martin J. , Van De Winkel Jan G. J. , Parren Paul W. H. I.
Published: February 2008

We evaluated the dose requirements for sustainedin vivoactivity of ofatumumab, a human anti‐CD20 antibody under development for the treatment of B cell‐mediated diseases. In a mouse xenograft model, a single dose, resulting in an initial plasma antibody concentration of 5 μg/ml, which was expected to result in full target saturation, effectively inhibited human B‐cell tumour development. Tumour growth resumed when plasma concentrations dropped below levels that are expected to result in half‐maximal saturation. Notably, tumour load significantly impacted antibody pharmacokinetics. In monkeys, initial depletion of circulating and tissue residing B cells required relatively high‐dose levels. Re‐population of B‐cell compartments, however, only became detectable when ofatumumab levels dropped below 10 μg/ml. We conclude that, once saturation of CD20 throughout the body has been reached by high initial dosing, plasma concentrations that maintain target saturation on circulating cells (5–10 μg/ml) are probably sufficient for sustained biological activity. These observations may provide a rationale for establishing dosing schedules for maintenance immunotherapy following initial depletion of CD20 positive (tumour) cells.
Polyandry and paternity skew in natural and experimental populations of Drosophila serrata
Authors: FRENTIU FRANCESCA D. , CHENOWETH STEPHEN F.
Published: February 2008

Many species engage in polyandry, resulting in the potential for sexual selection to continue post‐copulation through sperm competition and/or cryptic female choice. The relative importance of pre‐ vs. post‐copulatory processes remains unknown for most species despite this information being fundamental for understanding the evolutionary consequences of sexual selection. The Australian fruit fly Drosophila serrata has become a prominent model system for studying precopulatory sexual selection, such as mating preferences and their influence on the evolution of sexually selected traits. Here, we investigated polyandry and the potential for post‐copulatory sexual selection in this species using indirect paternity analysis. We genotyped 21 wild‐caught and 19 laboratory‐reared mothers and their offspring (a total of 787 flies) at six microsatellite loci and found extensive polyandry, with all broods surveyed having at least two sires. Female remating rates were higher than in other Drosophila surveyed to date and no significant differences were found between laboratory and field populations. Additionally, we found evidence for biased sperm usage in several broods of D. serrata. Paternity skew occurred more frequently in broods from the field population than the laboratory one, suggesting differences between the two environments in the level of post‐copulatory sexual selection. Our data suggest that D. serrata represents a promising system for studying the interaction between pre‐ and post‐copulatory sexual selection in driving the evolution of sexually selected phenotypes.
‘Social heterosis’ as a process that maintains genetic variation – a comment
Authors: SANTOS M.
Published: February 2008

In the ‘mating pool’ mode of reproduction, offspring genotypes at each generation are taken randomly from a common population and subdivided into groups where individuals representing a finite sample from the pooled distribution reproduce proportional to their fitness. Assuming that genetically diverse groups contribute more offspring, a recent article by Nonacs & Kapheim [J. Evol. Biol. 20 (2007) 2253] shows that allelic diversity can be easily maintained and proposes the process of ‘social heterosis’ as a potentially powerful mechanism that accounts for a significant amount of genetic variation. Contrary to their suggestions, I show here that there is a reduced efficiency of selection and an increased probability of fixation of segregating alleles when many loci are simultaneously undergoing social heterosis even if independence of action of the different loci and linkage equilibrium are assumed. The critical issue is that linkage disequilibria are generated by the sampling process of creating small groups and interfere with selection.
Phenotypic integration and conserved covariance structure in calopterygid damselflies
Authors: EROUKHMANOFF F. , SVENSSON E. I.
Published: February 2008

By comparing the phenotypic (P) variance–covariance matrices between closely related taxa or conspecific populations, one can study the outcome of the interplay between selection and developmental constraints in phenotypic evolution. Shared patterns of phenotypic integration are also of interest and might result from similarities in either selection or developmental pathways. We comparedP‐matrices and phenotypic integration indices between populations and species of the damselfly genusCalopteryx.Pmax‐comparisons between parapatricC. splendenspopulations revealed stronger conserved phenotypic covariance structure thanPmax‐comparisons between species, suggesting that divergence in its early stages proceeds along phenotypic lines of least resistance. Within‐ and among‐population correlations inC. splendenswere highly concordant, in further support of initial divergence alongPmax. Despite some similarities in overall phenotypic integration betweenC. splendensandC. virgo, these two species only had severalP‐matrix eigenvectors in common, indicating that after reproductive isolation, divergence has proceeded againstPmax.
Rapid evolution towards heavy metal resistance by mountain birch around two subarctic copper–nickel smelters
Authors: ERÄNEN J. K.
Published: February 2008

Adaptations to pollution among long‐lived trees have rarely been documented, possibly because of their long reproductive cycles and the evolutionarily short timescales of anthropogenic pollution. Here, I present the results of a greenhouse experiment that suggest rapid evolutionary adaptation of mountain birch [Betula pubescenssubsp.czerepanovii(Orlova) Hämet‐Ahti] to heavy metal (HM) stress around two copper–nickel smelters in NW Russia. The adaptation incurs a cost with reduced performance of adapted seedlings in pristine conditions. The industrial barrens around the studied smelters are extremely high‐stress sites with low seed germination and survival. It is likely that strong natural selection has eliminated all sensitive genotypes within one or two generations, with only the most tolerant individuals persisting and producing adapted seeds in the individual barrens. The results were similar from around both smelters, suggesting parallel evolution towards HM resistance.
Correlated evolution between male ejaculate allocation and female remating behaviour in seed beetles (Bruchidae)
Authors: KATVALA M. , RÖNN J. L. , ARNQVIST G.
Published: February 2008

Sperm competition theory suggests that female remating rate determines the selective regime that dictates the evolution of male ejaculate allocation. To test for correlated evolution between female remating behaviour and male ejaculate traits, we subjected detailed experimental data on female and male reproductive traits in seven‐seed beetle species to phylogenetic comparative analyses. The evolution of a larger first ejaculate was positively correlated with the evolution of a more rapid decline in ejaculate size over successive matings. Further, as predicted by theory, an increase in female remating rate correlated with the evolution of larger male testes but smaller ejaculates. However, an increase in female remating was associated with the evolution of a less even allocation of ejaculate resources over successive matings, contrary to classic sperm competition theory. We failed to find any evidence for coevolution between the pattern of male ejaculate allocation and variation in female quality and we conclude that some patterns of correlated evolution are congruent with current theory, whereas some are not. We suggest that this may reflect the fact that much sperm competition theory does not fully incorporate other factors that may affect the evolution of male and female traits, such as trade‐offs between ejaculate expenditure and other competing demands and the evolution of resource acquisition.
Evolution of sex‐biased maternal effects in birds. IV. Intra‐ovarian growth dynamics can link sex determination and sex‐specific acquisition of resources
Authors: BADYAEV A. V. , YOUNG R. L. , HILL G. E. , DUCKWORTH R. A.
Published: February 2008

The evolutionary importance of maternal effects is determined by the interplay of maternal adaptations and strategies, offspring susceptibility to these strategies, and the similarity of selection pressures between the two generations. Interaction among these components, especially in species where males and females differ in the costs and requirements of growth, limits inference about the evolution of maternal strategies from their expression in the offspring phenotype alone. As an alternative approach, we examine divergence in the proximate mechanisms underlying maternal effects across three house finch populations with contrasting patterns of sex allocation: an ancestral population that shows no sex‐biased ovulation, and two recently established populations at the northern and southern boundaries of the species range that have opposite sequences of ovulation of male and female eggs. For each population, we examined how oocyte acquisition of hormones, carotenoids and vitamins was affected by oocyte growth and overlap with the same and opposite sexes. Our results suggest that sex‐specific acquisition of maternal resources and sex determination of oocytes are linked in this system. We report that acquisition of testosterone by oocytes that become males was not related to growth duration, but instead covaried with temporal exposure to steroids and overlap with other male oocytes. In female oocytes, testosterone acquisition increased with the duration of growth and overlap with male oocytes, but decreased with overlap with female oocytes. By contrast, acquisition of carotenoids and vitamins was mostly determined by organism‐wide partitioning among oocytes and oocyte‐specific patterns of testosterone accumulation, and these effects did not differ between the sexes. These results provide important insights into three unresolved phenomena in the evolution of maternal effects – (i) the evolution of sex‐specific maternal allocation in species with simultaneously developing neonates of both sexes; (ii) the link between sex determination and sex‐specific acquisition of maternal products; and (iii) the evolution of context‐dependent modulation of maternal effects.
Incidence of Prunus necrotic ring spot virus on Malus domestica in India
Authors: Chandel V. , Rana T. , Handa A. , Thakur P. D. , Hallan V. , Zaidi A. A.
Published: February 2008

In surveys of apple (Malus domestica) orchards in various parts of Himachal Pradesh, samples from trees showing necrotic symptoms on the leaves were collected and tested for detection of Prunus necrotic ringspot virus (PNRSV) initially by ELISA followed by RT‐PCR using coat protein gene primers. Positive results were obtained in samples from Kullu and Kalpa regions. The virus gene sequences showed 88–97% similarity to corresponding sequences of other PNRSV isolates deposited in the GenBank database using ncbi.nih.nlm.gov. Although the similarity was high, there were some distinct differences with the Spanish isolate. This is the first report of PNRSV in apple from India.
INITIAL FRACTURE MECHANISMS IN NICKEL ALLOYED PM STEEL
Authors: Drar H. , Bergmark A.
Published: February 2008

Abstract—Initial fatigue crack propagation mechanisms at near threshold conditions were studied for four nickel‐alloyed, powder‐metallurgy (PM) steels. Fatigue fracture surfaces were obtained by testing smooth rectangular specimens at 30 Hz and under constant amplitude and zero mean stress conditions. Materials based on Distaloy AE were used in two densities, namely 7.15 and 7.45 g/cm3.

All the fracture surfaces were composed of three morphological regions (i) a macrocrack initiation region Rl where cracks propagated preferentially through particles (ii) a macrocrack growth region R2 and (iii) an unstable crack growth region R3 where cracks propagated preferentially between particles. Initial fatigue crack growth, in region R1, was controlled by the propagation of short cracks whose dimensions were comparable to the material microstructure. The subsequent fatigue crack growth in regions R2 and R3 was controlled by ductile rupture between microvoids. Transparticle fracture in region R1 was independent of pore distribution, while interparticle fracture in regions R2 and R3 was dependent on pore distribution.
THE ELECTRON CHANNELLING CONTRAST TECHNIQUE APPLIED TO THE CHARACTERISATION OF DISLOCATION STRUCTURES IN THE VICINITY OF A FATIGUE CRACK
Authors: Chen D. L. , Melisova D. , Weiss B. , Stickler R.
Published: February 2008

Abstract—In this investigation the Electron Channelling Contrast (ECC) technique in scanning electron microscopy (SEM) was applied to reveal the dislocation structures in the vicinity of surface fatigue cracks in comparison to those of cyclically‐deformed recrystallized polycrystalline copper. The plastic zone around a fatigue crack was found to consist of an innermost region containing cells, followed by a region containing dense veins and PSBs, surrounded by a structure of loose veins, bundles and loop patches typical of the cyclically deformed matrix. A relation between plastic strain amplitude values deduced from cyclic stress‐strain investigations and the dislocation structures near fatigue cracks are given. Typical regions of damage accumulation were identified and plastic strain contours for surface fatigue cracks established. The essentially non‐destructive ECC technique is particularly suited to identify the changes in mesoscopic dislocation structures from surface layers to the interior of specimens over large specimen areas.
AN ACCELERATED TEST METHOD FOR DETERMINING NEAR‐THRESHOLD STRESS INTENSITY VALUES IN HSLA STEELS
Authors: Liu‐Nash G. , Todd J. A. , Mostovoy S.
Published: February 2008

Abstract— A new method for accelerating the collection of near‐threshold corrosion fatigue crack propagation data, using local hydrogen embrittlement in the crack tip region, has been investigated for ASTM A710 HSLA steel. Fatigue tests were conducted at 10 and 0.2 Hz (stress ratio, R= 0.1) on “constant K” contoured double cantilever beam (CDCB) specimens, to establish near‐threshold crack growth rates in a locally hydrogen charged region at the crack tip. Hydrogen charging was then discontinued and crack growth rates were monitored in the uncharged material. Near‐threshold fatigue crack growth rates were found to be 100 times faster in the locally hydrogen charged specimens than in the uncharged material. Fatigue thresholds, ΔKth, were defined in less than one fifth the time required for load shedding tests in air at 0.2 Hz. Although demonstrated for HSLA steels, the technique is applicable to any material which can be embrittled by hydrogen.