bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of acrylic dry spinning production line by using artificial neural network and genetic algorithm
Authors: Vadood M. , Semnani D. , Morshed M.
Published: November 2010

Acrylic fibers are synthetic fibers with wide applications. A couple of methods can be utilized in their manufacture, one of which is the dry spinning process. The parameters in this method have nonlinear relationships, making the process very complex. To the best of the authors' knowledge, no comprehensive study has yet been conducted on the optimization of acrylic dry spinning production using computer algorithms. In this study, such parameters as extruder temperature in and around the head, solution viscosity, water content in the solution, formic acid content of the solution, and the retention time of the solution in the reactor were measured in an attempt to predict the behavior of the dry spinning process. The color index of the manufactured fibers was used as an indicator of production quality and statistical methods were employed to determine the parameters affecting the process. An artificial neural network (ANN) using the back propagation training algorithm was then designed to predict the color index. ANN parameters including the number of hidden layers, number of neurons in each layer, adaptive learning rate, activation functions, number of max fail epochs, validation and test data were optimized using a genetic algorithm (GA). The trial and error method was used to optimize the GA parameters like population size, number of generations, crossover or mutation rates, and various selection functions. Finally, an ANN with a high accuracy was designed to predict the behavior of the dry spinning process. This method is capable of preventing the manufacturing of undesired fibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Bayesian mixture models for the incorporation of prior knowledge to inform genetic association studies
Authors: Fridley Brooke L. , Serie Daniel , Jenkins Gregory , White Kristin , Bamlet William , Potter John D. , Goode Ellen L.
Published: November 2010

In the last decade, numerous genome‐wide linkage and association studies of complex diseases have been completed. The critical question remains of how to best use this potentially valuable information to improve study design and statistical analysis in current and future genetic association studies. With genetic effect size for complex diseases being relatively small, the use of all available information is essential to untangle the genetic architecture of complex diseases. One promising approach to incorporating prior knowledge from linkage scans, or other information, is to up‐ or down‐weightP‐values resulting from genetic association study in either a frequentist or Bayesian manner. As an alternative to these methods, we propose a fully Bayesian mixture model to incorporate previous knowledge into on‐going association analysis. In this approach, both the data and previous information collectively inform the association analysis, in contrast to modifying the association results (P‐values) to conform to the prior knowledge. By using a Bayesian framework, one has flexibility in modeling, and is able to comprehensively assess the impact of model specification on posterior inferences. We illustrate the use of this method through a genome‐wide linkage study of colorectal cancer, and a genome‐wide association study of colorectal polyps.Genet. Epidemiol. 34:418–426, 2010. © 2010 Wiley‐Liss, Inc.
Using cases to strengthen inference on the association between single nucleotide polymorphisms and a secondary phenotype in genome‐wide association studies
Authors: Li Huilin , Gail Mitchell H. , Berndt Sonja , Chatterjee Nilanjan
Published: November 2010

Case‐control genome‐wide association studies provide a vast amount of genetic information that may be used to investigate secondary phenotypes. We study the situation in which the primary disease is rare and the secondary phenotype and genetic markers are dichotomous. An analysis of the association between a genetic marker and the secondary phenotype based on controls only (CO) is valid, whereas standard methods that also use cases result in biased estimates and highly inflated type I error if there is an interaction between the secondary phenotype and the genetic marker on the risk of the primary disease. Here we present an adaptively weighted (AW) method that combines the case and control data to study the association, while reducing to the CO analysis if there is strong evidence of an interaction. The possibility of such an interaction and the misleading results for standard methods, but not for the AW or CO approaches, are illustrated by data from a case‐control study of colorectal adenoma. Simulations and asymptotic theory indicate that the AW method can reduce the mean square error for estimation with a prespecified SNP and increase the power to discover a new association in a genome‐wide study, compared to CO analysis. Further experience with genome‐wide studies is needed to determine when methods that assume no interaction gain precision and power, thereby can be recommended, and when methods such as the AW or CO approaches are needed to guard against the possibility of nonzero interactions. Genet. Epidemiol. 34:427–433, 2010. Published 2010 Wiley‐Liss, Inc.
An “almost exhaustive” search‐based sequential permutation method for detecting epistasis in disease association studies
Authors: Ma Li , Assimes Themistocles L. , Asadi Narges B. , Iribarren Carlos , Quertermous Thomas , Wong Wing H.
Published: November 2010

Due to the complex nature of common diseases, their etiology is likely to involve “uncommon but strong” (UBS) interactive effects—i.e. allelic combinations that are each present in only a small fraction of the patients but associated with high disease risk. However, the identification of such effects using standard methods for testing association can be difficult. In this work, we introduce a method for testing interactions that is particularly powerful in detecting UBS effects. The method consists of two modules—one is a pattern counting algorithm designed for efficiently evaluating the risk significance of each marker combination, and the other is a sequential permutation scheme for multiple testing correction. We demonstrate the work of our method using a candidate gene data set for cardiovascular and coronary diseases with an injected UBS three‐locus interaction. In addition, we investigate the power and false rejection properties of our method using data sets simulated from a joint dominance three‐locus model that gives rise to UBS interactive effects. The results show that our method can be much more powerful than standard approaches such as trend test and multifactor dimensionality reduction for detecting UBS interactions. Genet. Epidemiol. 34:434–443, 2010. © 2010 Wiley‐Liss, Inc.
Analyze multivariate phenotypes in genetic association studies by combining univariate association tests
Authors: Yang Qiong , Wu Hongsheng , Guo Chao‐Yu , Fox Caroline S.
Published: November 2010

Multivariate phenotypes are frequently encountered in genome‐wide association studies (GWAS). Such phenotypes contain more information than univariate phenotypes, but how to best exploit the information to increase the chance of detecting genetic variant of pleiotropic effect is not always clear. Moreover, when multivariate phenotypes contain a mixture of quantitative and qualitative measures, limited methods are applicable. In this paper, we first evaluated the approach originally proposed by O'Brien and by Wei and Johnson that combines the univariate test statistics and then we proposed two extensions to that approach. The original and proposed approaches are applicable to a multivariate phenotype containing any type of components including continuous, categorical and survival phenotypes, and applicable to samples consisting of families or unrelated samples. Simulation results suggested that all methods had valid type I error rates. Our extensions had a better power than O'Brien's method with heterogeneous means among univariate test statistics, but were less powerful than O'Brien's with homogeneous means among individual test statistics. All approaches have shown considerable increase in power compared to testing each component of a multivariate phenotype individually in some cases. We apply all the methods to GWAS of serum uric acid levels and gout with 550,000 single nucleotide polymorphisms in the Framingham Heart Study. Genet. Epidemiol. 34:444–454, 2010. © 2010 Wiley‐Liss, Inc.
Housekeepers for accurate transcript expression analysis in Alzheimer's disease autopsy brain tissue
Authors: Gebhardt Florian M. , Scott Heather A. , Dodd Peter R.
Published: November 2010

Background

Quantitative real‐time reverse transcription–polymerase chain reaction (qRT‐PCR) is a popular technique for mRNA expression studies. Normalization to an endogenous reference transcript (housekeeper) is widely used to correct for differences in loading and RNA quality. Alzheimer's disease (AD) alters brain metabolism. The stability of housekeeper transcript expression must be carefully validated.

Methods

qRT‐PCR was used to assess eight putative housekeeper transcripts in four brain regions from 15 control, 12 AD, and 10 AD/Lewy body disease (LBD) cases.

Results

RNA quality is lower in AD and AD/LBD than in controls. Frequently used housekeepers such as glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) and β‐actin had lower overall expression in AD and AD/LBD cases than in controls. RPL13 and 18S were the most stably expressed housekeepers tested. Synaptophysin and glial fibrillary acidic protein were used to evaluate normalized quantification. By using different housekeepers we confirmed that synaptophysin expression was down‐regulated in AD cases, whereas glial fibrillary acidic protein expression was increased.

Conclusions

Among all candidates tested, RPL13 was the best housekeeper for qRT‐PCR studies in autopsy brain tissue samples from controls and AD cases. RNA quality should be assessed and data normalized on this index as well.
Exercise and cognition: Results from the National Long Term Care Survey
Authors: Jedrziewski M. Kathryn , Ewbank Douglas C. , Wang Haidong , Trojanowski John Q.
Published: November 2010

Background

Age remains a robust risk factor for Alzheimer's disease as well as other dementias. Therefore, the aging of the population in the United States will result in dramatic increases in the prevalence of dementia if preventative interventions are not identified. The aim of this study was to examine potential associations between exercise and lowering the risk of cognitive impairment.

Methods

National Long Term Care Survey data were used. Level of exercise participation was measured at baseline (1994) and cognitive impairment status was measured at baseline and 5‐ and 10‐year follow‐up. Linear regression was performed, controlling for age, sex, education, baseline score on cognitive test, diabetes, and hypertension.

Results

At 10‐year follow‐up, the number of different types of exercises performed was inversely associated with the onset of cognitive impairment (P = .002) as was the number of exercise sessions lasting at least 20 minutes (P = .007).

Conclusion

Study results from National Long Term Care Survey data provide evidence supporting the potential for exercise to lower the risk of dementia.
High normal fasting blood glucose is associated with dementia in Chinese elderly
Authors: Mortimer James A. , Borenstein Amy R. , Ding Ding , DeCarli Charles , Zhao Qianhua , Copenhaver Cathleen , Guo Qihao , Chu Shugang , Galasko Douglas , Salmon David P. , Dai Qi , Wu Yougui , Petersen Ronald , Hong Zhen
Published: November 2010

Background

Diabetes is a risk factor for mild cognitive impairment (MCI) and dementia. However, the association between high normal fasting blood glucose (FBG) and dementia has not been studied.

Methods

Polytomous logistic regression was used to assess the association of dementia and MCI with FBG in an age‐ and sex‐matched sample of 32 dementia patients, 27 amnestic MCI (aMCI) patients, and 31 normal controls (NC). Analyses were repeated for those with normal FBG. Correlations between FBG and cognitive test scores were obtained.

Results

Controlling for age, gender, education, body mass index, Hachinski Ischemic Score, magnetic resonance imaging (MRI) stroke, and normalized brain, hippocampal, and white matter hyperintensity MRI volumes; higher FBG was associated with dementia versus aMCI status (OR = 3.13; 95% CI, 1.28–7.69). This association remained (OR = 7.75; 95% CI, 1.10–55.56) when analyses were restricted to subjects with normal FBG. When dementia patients were compared with NC adjusting for age, gender, and education, a significant association with FBG also was seen (OR = 1.83; 95% CI, 1.09–3.08), but it was lost when vascular covariates were added to the model. FBG was not associated with aMCI status versus NC. Higher FBG was correlated with poorer performance on the Trailmaking Test Part B (P = .003). The percentage of dementia patients with high normal FBG (90%) was significantly higher than that of aMCI patients with high normal FBG (32.9%) (χ2 = 13.9, P < .001).

Conclusions

Higher FBG was associated with dementia (vs. aMCI) independent of vascular risk factors and MRI indicators of vascular disease, and remained a significant risk factor when analyses were restricted to subjects with normal FBG. The results of this cross‐sectional study suggest that a high normal level of FBG may be a risk factor for dementia.
Predicting cognitive decline in Alzheimer's disease: An integrated analysis
Authors: Lopez Oscar L. , Schwam Elias , Cummings Jeffrey , Gauthier Serge , Jones Roy , Wilkinson David , Waldemar Gunhild , Zhang Richard , Schindler Rachel
Published: November 2010

Background

Numerous patient‐ and disease‐related factors increase the risk of rapid cognitive decline in patients with Alzheimer's disease (AD). The ability of pharmacological treatment to attenuate this risk remains undefined.

Methods

Pooled data from 14 randomized clinical studies of donepezil in the treatment of AD (N = 3748) were analyzed to identify predictors of fast decline and determine the effect of donepezil on the risk of fast decline.

Results

Young age and more severe baseline cognitive, global, or behavioral status were identified as independent predictors of faster decline in placebo‐treated patients. Multivariate models indicated that donepezil treatment was associated with a 39% to 63% reduction in the risk of faster decline.

Conclusions

These results correspond with previous findings, indicating relationships between age or baseline disease severity and rates of cognitive decline. Furthermore, they suggest that symptomatic therapy for AD could reduce the likelihood of faster decline in treated patients.
Healthy aging and preclinical dementia: The United States–Israel Longitudinal Database Project
Authors: Khachaturian Ara S. , Chapman Joab , Farrer Lindsay , Friedland Robert P. , Ebstein Richard , Grossman Iris , Hendler Talma , Hermann Bruce , Inzelberg Rivka , Johnson Sterling , Khachaturian Zaven S. , Lichter‐Shapira Irit , Makeeva Oksana , Mayrl Robin , Mizrahi Eli , Roses Allen D. , Sager Mark , Fraifeld Shifra
Published: November 2010

This article proposes the establishment of a United States–Israel Longitudinal Database for Healthy Aging and Preclinical Dementia as a prototype model for the eventual creation of an international database. It is envisioned that such a comprehensive international database, as a shared research resource, will provide the foundation for a systems approach to solve the dual public health problems of: (1) Early detection of individuals at an elevated risk of developing Alzheimer's disease, and (2) Developing interventions to delay onset of, or prevent, chronic brain disorders later in life.
Who’s to Blame? The Distribution of Responsibility in Developing Democracies
Authors: Alcañiz Isabella , Hellwig Timothy
Published: November 2010

International structures tie the hands of policy makers in the developing world. Dependency on the world economy is blamed for low growth, high volatility and less redistribution of income than average, but the effect of international constraints on mass politics is relatively unknown. This study examines how citizens of developing democracies assign responsibility for policy outcomes. A theory of the distribution of responsibility, combining insights from the political economy of development and the study of mass behaviour, is presented. Evidence from seventeen Latin American countries shows that citizens often blame policy outcomes on international and private-sector actors, to which they, as voters, have no direct recourse. Ties to world markets and the International Monetary Fund, especially foreign debt, shift responsibility towards international actors and tend to exonerate national politicians.
Field optimization of the sex pheromone of Stenoma catenifer (Lepidoptera: Elachistidae): evaluation of lure types, trap height, male flight distances, and number of traps needed per avocado orchard for detection
Authors: Hoddle M.S. , Millar J.G. , Hoddle C.D. , Zou Y. , McElfresh J.S. , Lesch S.M.
Published: November 2010

The sex pheromone of Stenoma catenifer was evaluated in commercial avocado orchards in Guatemala to determine operational parameters, such as optimal lure type, trap height, trap density and estimates of the distances that male moths fly. Of four pheromone dispensers tested, gray and white rubber septa were of equal efficacy, whereas 1-ml low-density polyethylene vials and 2×3-cm polyethylene ziplock bags were least efficacious. The height at which wing traps were hung did not significantly affect the number of adult male S. catenifer captured. For monitoring S. catenifer, these data suggest that the pheromone should be dispensed from gray rubber septa in wing traps hung inside the tree canopy at 1.75 m, a height convenient for trap placement and monitoring. Mark-recapture studies of male S. catenifer indicated that, on average, males flew 67 m in one night. However, it is likely that this is an underestimate of the distance that male moths are capable of flying in a single night. Probabilistic modeling of S. catenifer capture data from different numbers of pheromone traps deployed in seven commercial avocado orchards of varying sizes and infestation levels suggested that 10–13 randomly deployed traps per orchard for a 7-day period are needed to detect at least one male S. catenifer with 90% confidence. These data provide sufficient information to develop effective protocols for using the S. catenifer pheromone to detect and monitor this pest in countries with endemic populations that are exporting fresh avocados, and for quarantine detection and incursion monitoring in countries receiving avocado imports from high risk areas.
PCR-based species identification ofAgrioteslarvae
Authors: Staudacher K. , Pitterl P. , Furlan L. , Cate P.C. , Traugott M.
Published: November 2010

Click beetle larvae within the genusAgriotes(Coleoptera: Elateridae), commonly known as wireworms, are abundant ground-dwelling herbivores which can inflict considerable damage to field crops. In Central Europe up to 20 species, which differ in their distribution, ecology and pest status, occur in arable land. However, the identification of these larvae based on morphological characters is difficult or impossible. This hampers progress towards controlling these pests. Here, we present a polymerase chain reaction (PCR)-based approach to identify, for the first time, 17Agriotesspecies typically found in Central Europe. Diagnostic sequence information was generated and submitted to GenBank, allowing the identification of these species via DNA barcoding. Moreover, multiplex PCR assays were developed to identify the nine most abundant species rapidly within a single-step reaction:Agriotes brevis, A. litigiosus, A. obscurus, A. rufipalpis, A. sordidus, A. sputator, A. ustulatus, A. lineatusandA. proximus. The latter two species remain molecularly indistinguishable, questioning their species status. The multiplex PCR assays proved to be highly specific against non-agrioted elaterid beetles and other non-target soil invertebrates. By testing the molecular identification system with over 900 field-collected larvae, our protocol proved to be a reliable, cheap and quick method to routinely identify Central EuropeanAgriotesspecies.
Crop and field boundary influences on the activity of a wide range of beneficial invertebrate groups on a split conventional/organic farm in northern England
Authors: Eyre M.D. , Leifert C.
Published: November 2010

Activity of 12 beneficial invertebrate groups was assessed in 2005 and 2006 on a farm in northern England split into conventional and organic management halves, using pitfall and pan traps set in both crops and field boundaries. Management, crop and boundary structure influences on invertebrate activity were assessed, as was the relationship between crop and boundary type. Classification of crop and boundary assemblages produced three and two groups, respectively, in both years. Organic arable crops had well-defined assemblages in both years; and, while grass and grass/clover fields were separated from conventional arable fields in 2005, there was mixing in 2006. One boundary group, in both years, was dominated by conventional arable fields with tall herbaceous boundary vegetation. The other group had more organic arable and grassy fields with shorter boundary vegetation. Redundancy analyses showed that a number of groups (Cantharidae, Coccinellidae, Syrphidae, Ichneumonidae, Braconidae, Proctotrupoidea, Lycosidae) were more active in organic arable fields with more Staphylinidae in conventional arable crops and no obvious trend with Carabidae, Hemiptera, Neuroptera and Linyphiidae. Activity of some groups, especially Coccinellidae, Syrphidae and parasitic wasps, was strongly related to weed cover. Staphylinidae were most active in tall herbaceous boundaries by conventional arable crops with more of a number of groups (Cantharidae, Coccinellidae, parasitic wasps) in short herbaceous boundaries by organic arable crops. Organic management produced most differences in aerially-dispersed invertebrates, and management had a profound effect on activity in field boundaries. Possible management prescriptions to increase invertebrate activity include changing sowing times, weed cover manipulation and field boundary and margin management.
Reproductive incompatibility between the B and Q biotypes of the whitefly Bemisia tabaci in China: genetic and behavioural evidence
Authors: Sun D.B. , Xu J. , Luan J.B. , Liu S.S.
Published: November 2010

The B and Q ‘biotypes’ of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) have been invading many parts of the world and causing severe damage to a range of crops. Recent phylogenetic analyses indicate that B and Q are cryptic species within the B. tabaci species complex. Although various attempts have been made to examine the reproductive compatibility between B and Q, few studies have tested the fertility of the F1 females and so the extent of possible gene flow remains unclear. In this study, we conducted a series of crossing experiments and behavioural observations to examine in detail the reproductive compatibility between the B and Q biotypes collected from Zhejiang, China, a region recently invaded by these whiteflies. Crossing experiments between the two biotypes using either single-pairs or small groups demonstrated that proportions of females in the F1 progeny were only 0–2% in the inter-biotype crosses compared to 58–68% in the intra-biotype treatments. Furthermore, all inter-biotype F1 females were sterile. Continuous video observations showed that B and Q adults very rarely copulated, and copulation occurred only when adults of opposite sex from different biotypes were enclosed in dense cohorts for a relatively long period of time. These data show that the B and Q biotypes examined in this study are completely isolated in reproduction. The isolation was due to mainly a copulation barrier, but post-copulation barriers were also involved.
Edge-induced narrowing of dietary diversity in leaf-cutting ants
Authors: Falcão P.F. , Pinto S.R.R. , Wirth R. , Leal I.R.
Published: November 2010

Much of the ecological alteration faced by human-modified Neotropical forests can be assigned to edge effects, including the proliferation of some voracious herbivores such as leaf-cutting ants. However, the underlying mechanisms/impacts of tropical forest edge on herbivores performance and their foraging behaviour (e.g. dietary diversity) have rarely been investigated. The goal of this study was, therefore, to determine whether and how the annual diet (i.e. species richness, diversity and the relative proportion of pioneer versus non-pioneer species of plant materials) of Atta cephalotes colonies differs in the forest edge versus the interior zone of a large remnant of Atlantic forest in northeastern Brazil. Among the key results was a strong habitat effect on dietary diversity (explaining ca. 40–50% of the variation), which, in edge colonies, decreased approximately by one fourth compared to interior colonies (inverse of Simpson's index: 3.7±0.84 versus 4.99±0.95). There was a predominance of leaf fragments collected from pioneer species in the diet in both habitat (86% in edge and 80.4% in interior). Edge colonies collected proportionally more fragments from pioneer species than colonies located in the forest interior. Our results are the first to demonstrate an edge-mediated relaxation of dietary restrictions in leaf-cutting ants. These findings render robust support to previous evidence indicating the reduction of bottom-up forces as a key factor explaining both edge-induced hyper-abundance and increased herbivory of leaf-cutting ants in human-modified Neotropical landscapes.
Modelling dynamic and irreversible powder compaction
Authors: SAUREL RICHARD , FAVRIE N. , PETITPAS F. , LALLEMAND M.-H. , GAVRILYUK S. L.
Published: November 2010

A multiphase hyperbolic model for dynamic and irreversible powder compaction is built. Four important points have to be addressed in this case. The first one is related to the irreversible character of powder compaction. When a granular media is subjected to a loading–unloading cycle, the final volume is lower than the initial one. To deal with this hysteresis phenomenon, a multiphase model with relaxation is built. During loading, mechanical equilibrium is assumed corresponding to stiff mechanical relaxation, while during unloading non-equilibrium mechanical transformation is assumed. Consequently, the sound speed of the limit models are very different during loading and unloading. These differences in acoustic properties are responsible for irreversibility in the compaction process. The second point is related to dynamic effects, where pressure and shock waves play an important role. Wave dynamics is guaranteed by the hyperbolic character of the equations. Phase compressibility as well as configuration energy are taken into account. The third point is related to multi-dimensional situations that involve material interfaces. Indeed, most processes with powder compaction entail free surfaces. Consequently, the model should be able to solve interfaces separating pure fluids and granular mixtures. Finally, the fourth point is related to gas permeation that may play an important role in some specific powder compaction situations. This poses the difficult question of multiple-velocity description. These four points are considered in a unique model fitting the frame of multiphase theory of diffuse interfaces (Saurel & Abgrall, J. Comput. Phys., vol. 150, 1999, p. 425; Kapila et al., Phys. Fluids, vol. 13, 2001, p. 3002; Saurel et al., J. Comput. Phys., vol. 228, 2009, p. 1678). The ability of the model to deal with these various effects is validated on basic situations, where each phenomenon is considered separately. Except for the material EOS (hydrodynamic and granular pressures and energies), which are determined on the basis of separate experiments found in the literature, the model is free of adjustable parameter.
Boundary-layer hydrodynamics and bedload sediment transport in oscillating water tunnels
Authors: GONZALEZ-RODRIGUEZ DAVID , MADSEN OLE SECHER
Published: November 2010

Oscillating water tunnels are experimental facilities commonly used in coastal engineering research. They are intended to reproduce near-bed hydrodynamic and sediment transport phenomena at a realistic scale. In an oscillating water tunnel, a piston generates an oscillatory motion that propagates almost instantaneously to the whole tunnel; consequently, flow is uniform along the tunnel, unlike the propagating wave motion in the sea or in a wave flume. This results in subtle differences between the boundary-layer hydrodynamics of an oscillating water tunnel and of a propagating wave, which may have a significant effect in the resulting sediment transport. In this paper, we present a zeroth-order analytical model of the turbulent boundary-layer hydrodynamics in an oscillating water tunnel. By using a time-varying eddy viscosity and by accounting for the constraints arising from the tunnel's geometry, the model predicts the oscillating water tunnel hydrodynamics and yields analytical expressions to compute bed shear stresses for asymmetric and skewed waves, both in the absence or presence of an imposed current. These expressions are applied to successfully quantify bedload sediment transport in oscillating water tunnel experiments.
The modulational instability in deep water under the action of wind and dissipation
Authors: KHARIF C. , KRAENKEL R. A. , MANNA M. A. , THOMAS R.
Published: November 2010

The modulational instability of gravity wave trains on the surface of water acted upon by wind and under influence of viscosity is considered. The wind regime is that of validity of Miles' theory and the viscosity is small. By using a perturbed nonlinear Schrödinger equation describing the evolution of a narrow-banded wavepacket under the action of wind and dissipation, the modulational instability of the wave group is shown to depend on both the frequency (or wavenumber) of the carrier wave and the strength of the friction velocity (or the wind speed). For fixed values of the water-surface roughness, the marginal curves separating stable states from unstable states are given. It is found in the low-frequency regime that stronger wind velocities are needed to sustain the modulational instability than for high-frequency water waves. In other words, the critical frequency decreases as the carrier wave age increases. Furthermore, it is shown for a given carrier frequency that a larger friction velocity is needed to sustain modulational instability when the roughness length is increased.
On the representation of Rossby waves on the β-plane by a piecewise uniform potential vorticity distribution
Authors: ZHU DA , NAKAMURA NOBORU
Published: November 2010

To bridge quasi-geostrophic dynamics and its discrete representation by a series of piecewise constant potential vorticity (PV), the dispersion relation for the Rossby wave in the single-layer β-plane is compared with that for the normal mode of edge waves straddling an infinite series of PV discontinuities (‘PV staircase’). It is shown that the edge waves over evenly spaced, uniform-height PV steps converge to the Rossby wave on the β-plane as Δ → 0, L → 0, Δ/L = βeff (Δ, L and βeff are the step size, step separation and the effective β, respectively), whereas they reduce to the single-step edge wave in the short-wave limit. For sufficiently small step separations, the difference in the phase velocities of the edge wave and the Rossby wave scales as O(L2). Two effects of increasing L on the zonal propagation are identified: (i) increased phase and group velocities in the short-wave limit due to an increased zonal wind at the PV steps and (ii) decreased phase and group velocities in the long-wave limit due to a decreased effective meridional tilt of the mode. The reduced tilt also severely limits the meridional group propagation. The relationship between the edge wave mode and the finite-difference approximation to the Rossby wave is also discussed.
Trochochaeta mexicana, a new species from an unusual family of Polychaeta, with comments on the world distribution of Trochochaetidae
Authors: Hernández-Alcántara Pablo , Solís-Weiss Vivianne
Published: November 2010

The small, monogeneric family of polychaetes known as Trochochaetidae has been exclusively collected in the northern hemisphere, mainly in temperate–cold environments. Nine species have been described so far includingTrochochaeta mexicanasp. nov. described herein, while one species remains unnamed. Only two species had previously been recorded in the eastern Pacific, soT. mexicanasp. nov. is the first record for the family in the tropical Mexican Biogeographic Province. The new species is characterized by having a pair of eyes, acicular neurochaetae on chaetigers 2 and 3, a small knob-like antenna and a nuchal crest projecting through chaetiger 1.Trochochaeta mexicanasp. nov., together withTrochochaeta kirkegaardi, Trochochaeta diverapodaandTrochochaeta cirriferaare the only trochochaetids that have been found exclusively in warm environments.
Morphometric and gonad maturity of the spider crab Libinia spinosa (Crustacea: Brachyura: Majoidea: Epialtidae) in Argentina
Authors: Sal Moyano M.P. , Gavio M.A. , Maggi M.D.
Published: November 2010

Morphometric and gonad maturity of Libinia spinosa on the coast of Mar del Plata, Argentina, were assessed. In both sexes various morphometric features were measured to determine the morphometric maturity, and through macroscopic inspection of gonads and analysis of its content, different stages of gonad maturity were described and the physiological maturity was estimated. In females, the carapace width ranged from 8 to 56.5 mm while in males from 4.6 to 81.97 mm. The size at which 50% of females were morphometrically mature was calculated at 40.6 mm. Based on the allometric growth of the abdomen, two morphometric groups of females were recognized as juvenile and adult phases. In males, results of principal component analysis showed that the most suitable variables that efficiently represent the size and sexual differentiation factor were the carapace width and cheliped length respectively. The size at which 50% of males were morphometrically mature was estimated at 58.9 mm. Based on the allometry of the cheliped growth, two morphometric groups were recognized as immature and mature phases. Males maintained under laboratory conditions moulted and growth was related to regular and terminal moults. Males reached their terminal moult at a wide size-range, from 48.5 mm to 61.4 mm of carapace width. This terminal moult coincided with the size of morphometric maturity. In both sexes four stages of gonad development were described, two corresponded to immature phases and two to mature phases. The size at which 50% of females and males reached gonad maturity was LC50 = 40.33 mm and LC50 = 33.6 mm, respectively. In females, both morphometric and gonad maturity occurred at a similar size. In males, gonad maturity is acquired prior to morphometric maturity, thus three different types of males were characterized: (1) those with small carapace width and cheliped, without spermatophores in their vas deferens; (2) those with large carapace width and small cheliped, bearing spermatophores in their vas deferens; and (3) those with large carapace width and cheliped, bearing spermatophores in their vas deferens.
On a class of stable conditional measures
Authors: MIHAILESCU EUGEN
Published: November 2010

The dynamics of endomorphisms (smooth non-invertible maps) presents many differences from that of diffeomorphisms or that of expanding maps; most methods from those cases do not work if the map has a basic set of saddle type with self-intersections. In this paper we study the conditional measures of a certain class of equilibrium measures, corresponding to a measurable partition subordinated to local stable manifolds. We show that these conditional measures are geometric probabilities on the local stable manifolds, thus answering in particular the questions related to the stable pointwise Hausdorff and box dimensions. These stable conditional measures are shown to be absolutely continuous if and only if the respective basic set is a non-invertible repeller. We find also invariant measures of maximal stable dimension, on folded basic sets. Examples are given, too, for such non-reversible systems.
Hegemonic metronome: the ascendancy of Western standard time
Authors: HOM ANDREW R.
Published: November 2010

To date, studies of international politics have little space for time. In this article, I argue that time is constitutive of the international system by offering a genealogical historical sketch of the coeval rise of territorial state sovereignty and Western standard time (consisting of seconds, minutes, and hours). Sovereignty is rightly a foundational concept of both the international system and the field of International Relations (IR), but the emergence of the contemporary method of reckoning time during the Enlightenment also supported the project of political modernity, and is thus critical to IR. The genealogical motive of the sketch is to understand what have become naturalised, global social conventions as historically contingent, cosmopolitical phenomena that resulted from significant socio-political efforts and conflicts. I locate ‘sites’ where modern sovereignty emerged and explicate contemporaneous processes, factors, and events implicated in the rise of modern time at those sites. In doing so, I outline how particular modes of understanding space and time were bred in Western Europe, spread around the world via colonialism, and embedded during the eras of global war and post-colonialism. I conclude by contrasting current challenges to territorial state sovereignty with Western standard time's untrammelled global hegemony.
How to compare regional powers: analytical concepts and research topics
Authors: NOLTE DETLEF
Published: November 2010

Although the concept of regional power is frequently used in International Relations (IR) literature, there is no consensus regarding the defining characteristics of a regional power. The article discusses different theoretical approaches that address the topic of power hierarchies in international politics and make reference to the concept of regional power. Marking differences as well as common ground with the more traditional concept of ‘middle powers’, the article outlines an analytical concept of regional powers adequate for contemporary IR research. The analytical dimensions of the framework may be employed to differentiate regional powers from other states and to compare regional powers with regard to their power status or relative power. Furthermore, the article investigates the possible repercussions of the rise of regional powers for international politics and discusses the probable importance and functions of regional governance structures for regional powers.
Power, leadership, and hegemony in international politics: the case of East Asia
Authors: NABERS DIRK
Published: November 2010

The article inquires into the conditions of effective leadership of states in international politics, and develops a framework for the study of so-called (new) regional powers such as Brazil, China, India, and South Africa in processes of regional institution-building. Various theoretical strands will be discussed as to the requirements of effective leadership in international affairs. Most importantly, the relationship between power, leadership and hegemony will be outlined. It is argued that the connection between leadership and hegemony is one of co-constitution. Leadership is necessarily based on hegemony, while hegemony can only be sustained through leadership. Furthermore, it will be shown that both leadership and hegemony are essentially political in character, whereas power has no such insinuation but has to be translated into leadership and hegemony through discursive means. Finally, the analysis asks for the preconditions of leadership in East Asia, using China's and Japan's roles in East Asian regionalism as an illustration.
Redistribution and recognition: what emerging regional powers want
Authors: NEL PHILIP
Published: November 2010

Regional powers of the Global South are perceived to be agents of change. But what exactly is the nature of the change that they want? This article argues that there is some continuity between the goals of the current generation of regional leaders and that of their predecessors. The current generation tend to have more confidence in their ability to effect the redistribution of wealth, prestige, and power in the global political economy, though, and tend therefore to be more integrationist than the first generation of post-colonial leaders. The goal of redistribution is premised on a more fundamental unfinished struggle of developing countries, one that Brazil, India, and South Africa in particular have taken up. This is the struggle for recognition of developing countries as full and equal partners in the society of states, but also as states with specific development needs that are too easily ploughed-under in the spurious universality promoted by the developed North. The struggle for recognition focuses on inclusive multilateralism and ‘non-indifference’ towards the development needs of the Global South. Using recent contributions to the theory of recognition, the article interprets these two goals as linked to the unfinished struggle against disrespect and humiliation.
Interruption Ashley
Authors: WEBER CYNTHIA
Published: November 2010

Rather than reading the work of Richard K. Ashley as iconic – as some dead, stable image used to signify the whole of post-modern or post-structural International Relations (IR) in a single swoop – this article considers Ashley's work as an interruption to the discipline of IR (mainstream and critical). In so doing, the article suggests that what is important about Ashley's work is how it creates a thinking space where it is possible to think again about international politics, about international theory, about what Ashley's interruption itself permits and limits and about how this interruption unfolds and sometimes folds back on itself.
Things lost and found: Richard Ashley and the silences of thinking space
Authors: LAFFEY MARK
Published: November 2010

Richard Ashley's writings in the 1980s are central to the production of post-structuralist or ‘dissident’ scholarship in International Relations (IR). In this article, I use analysis of the standard dissident view of Ashley's writings to examine the interpretive practices through which the community of dissident scholars was produced textually. Dissident ‘thinking space’ in the discipline was produced in part through the exclusion of Marx, capital and class, despite these being present in Ashley's writings throughout this period. Similar interpretive practices were applied to the writings of Michel Foucault, with similar effects. This exclusion has negative consequences for dissident scholarship, in particular analysis of historicity and the place of capitalism in contemporary world politics. Overcoming these problems requires reading the work of Ashley and other founders of dissident scholarship in a different way are attentive to the silences of thinking space.
Dissidence, Richard K. Ashley, and the politics of silence
Authors: GRAYSON KYLE
Published: November 2010

Within the academy we are taught to look for silence – as a noun. We are counselled to find gaps in the literature or empirical case studies that have yet to be researched in order to bring our own voice to the issues that they raise. But, there is a tension with the other face of silence, when it assumes the form of a verb. Silence and silencing have therefore been integral motivators for the entire spectrum of ‘critical’ literature within international studies, not only to show what cannot be spoken or thought about within international studies but also, at times, how this can be a deliberate political practice. But there remains a hope. The hope is that the catalyst for transformation – not merely change – is within that which we already know and that which we already have the ability to articulate or to speak. But should we take these assumptions for granted? It is at this precise point where the concerns of Richard K. Ashley with dissidence can combine with the conceptual provocations of the case of the Pirahã people of western Amazonia to generate some uncertainty about the revelations that ‘critical’ scholarship often wants to provide.
Does size matter? Subsegmental cues to vowel mispronunciation detection
Authors: MANI NIVEDITA , PLUNKETT KIM
Published: November 2010

Children look longer at a familiar object when presented with either correct pronunciations or small mispronunciations of consonants in the object's label, but not following larger mispronunciations. The current article examines whether children display a similar graded sensitivity to different degrees of mispronunciations of the vowels in familiar words, by testing children's sensitivity to 1-feature, 2-feature and 3-feature mispronunciations of the vowels of familiar labels: Children aged 1 ; 6 did not show a graded sensitivity to vowel mispronunciations, even when the trial length was increased to allow them more time to form a response. Two-year-olds displayed a robust sensitivity to increases in vowel mispronunciation size, differentiating between small and large mispronunciations. While this suggests that early lexical representations contain information about the features contributing to vocalic identity, we present evidence that this graded sensitivity is better explained by the acoustic characteristics of the different mispronunciation types presented to children.
Improving studies of resource selection by understanding resource use
Authors: KERTSON BRIAN N. , MARZLUFF JOHN M.
Published: November 2010

Understanding the resource needs of animals is critical to their management and conservation. Resource utilization functions (RUFs) provide a framework to investigate animal-resource relationships by characterizing variation in the amount of resource use. In this context a ‘resource’ is any aspect of a species' fundamental niche that can be mapped throughout the area of investigation (such as study area or home range). Extensive global positioning system (GPS) data from 17 cougars (Puma concolor) demonstrate the utility and potential challenges of estimating RUFs within the home range for far-ranging species. Ninety-nine per cent utilization distributions (UDs) estimated using bivariate plug in, univariate least-squares cross-validation and reference bandwidth selection methods were compared. Distance to water, per cent clear-cut and regenerating forest, and slope were used to estimate cougar RUFs. UDs derived from GPS data were more refined, and plug-in UDs were least similar to UDs derived from other bandwidths. RUFs were resilient to variation in the smoothing parameter, with all methods yielding coefficients that largely reflected observations of foraging ecology and behaviour. Cougars were individualistic, but use was generally positively associated with the presence of regenerating forest and inversely associated with steep slopes. Advances in technology allow for greater accuracy and resolution of the UD, but software improvements and spatially explicit information on animal behaviour are needed to better understand resource use.