bluuebunny/crossref_metadata_2025 huggingface dataset:
Field studies on colour preferences of Ctenarytaina thysanura in Tasmanian boronia farms
Authors: Mensah R. K. , Madden J. L.
Published: April 2011

Field tests on attraction of Ctenarytaina thysanura (Hemiptera: Psyllidae) adults to different coloured 30 × 30 cm sticky traps revealed a preference for yellow. Among the enamel colours tested, more psyllids were captured on yellow traps followed by green, then blue and least on red, cyan and magenta. Dilution of yellow enamel with 50% white (1Y:1W) and 75% white (1Y:3W) to produce yellow‐white hues resulted in a significant decrease in psyllid capture indicating that the psyllids response to yellow was one of positive attraction and could suggest true colour discrimination. Reflectance spectra of painted surfaces of the enamel colours and also yellow to white hues indicated that psyllid capture rates were directly related to the proportion of light reflected in the 500–560 nm region. The biological basis of the observed C. thysanura response may be that yellow is the most intensely reflective colour in the general part of the spectrum for leaves which reflect most light in the 500–600 nm (peak 550 nm) range.
The effects of a multispecies sequential diet on the growth and survival of a tropical polyphagous caterpillar
Authors: Pescador A. R.
Published: April 2011

Hylesia lineata Druce (Lepidoptera: Saturniidae) caterpillars are highly polyphagous at the individual level. I examined the effects of a multispecies sequential diet on the performance of the larvae. The experiment included three natural hosts respectively – Casearia corymbosa HBK, Thouinia paucidentata Radlk., and Erythroxylum havanense Jacq – used by ovipositing females in proportion as expected by their abundance; C. corymbosa and E. havanense representing the most and least abundant hosts respectively. All possible two‐host and single‐host diets were tested. Larval survival to the pupal stage (as protected by a field cage) did not differ among all diets. Also, for females, regardless of the identity of the initial host, the final weight and the developmental time depended entirely on the nature of the final host. Male performance, in contrast, only differed in terms of developmental time but again the initial host did not affect the final result. It was concluded that a host switch early in the development of the caterpillars does not affect further growth on the other host plants. Caterpillars that finished their development on E. havanense reached small sizes but females devoted a larger proportion of their resources to egg biomass; as a result female fertility was similar among females regardless of their feeding history. I concluded that the caterpillar's abilities and the female compensatory flexibility may oppose selection for a strong preference hierarchy in the female ovipositing behavior.
Sweetpotato whitefly resistance to insecticides in Hawaii: intra‐island variation is related to insecticide use
Authors: Omer A. D. , Johnson M. W. , Tabashnik B. E. , Costa H. S. , Ullman D. E.
Published: April 2011

Susceptibility to acephate, methomyl, and permethrin was determined with laboratory bioassays of field‐collected adults from 15 populations of the B biotype of sweetpotato whitefly, Bemisia tabaci (Gennadius) (Homoptera:Aleyrodidae), from Hawaii. Comparisons at the LC50 showed up to 24‐fold resistance to acephate, 18‐fold resistance to methomyl, and 4‐fold resistance to permethrin. Analysis of variance showed significant intra‐island variation in susceptibility to each insecticide, but no significant variation among islands. Insecticide use varied from 4 to 103 insecticide sprays per site per season. Acephate and methomyl were used more often than permethrin. The frequency of application and LC50 for each insecticide were positively correlated across sites. These results suggest that local variation in insecticide use was a primary cause of variation in susceptibility. If local insecticide use is a key determinant of resistance, as our results suggest, growers can retard resistance development locally by reducing their own insecticide use.
Suitability of greenbugs, cotton aphids, and Heliothis virescens eggs for development and reproduction of Orius insidiosus
Authors: Bush L. , Kring T. J. , Ruberson J. R.
Published: April 2011

Development, fecundity, and longevity of the predator, Orius insidiosus (Say) (Heteroptera: Anthocoridae), when reared on greenbug [Schizaphis graminum (Rondani)], cotton aphid (Aphis gossypii Glover), or eggs of tobacco budworm [Heliothis virescens (F.)] with green beans or water were examined. Developmental time was shortest when predators were reared on H. virescens eggs and beans and longest when reared on cotton aphids and water. Predators were most fecund when fed H. virescens eggs. The inclusion of beans in the nymphal diet further enhanced fecundity when fed eggs. Longevity of both females and males was significantly shorter when reared on aphids than on eggs. Beans in the nymphal diet enhanced longevity of female predators only in combination with budworm eggs. Female O. insidiosus were largest when reared on H. virescens eggs. Addition of green beans in aphid treatments resulted in increased size of O. insidiosus when compared to aphids and free water.
Reproductive diapause and quiescence in a tropical rice bug, Leptocorisa oratorius
Authors: Ito Kiyomitsu , Nik Mohd. Noor N.S.
Published: April 2011

Experiments were carried out to analyze the effects of food supply and photoperiod on the induction of dormancy in Leptocorisa oratorius Fabricius (Heteroptera: Alydidae) adults in Alor Setar (latitude 6.1° N), West Malaysia. When the adults were deprived of food, they ceased oviposition, became tolerant to starvation, and their oxygen consumption rate decreased, but they did not accumulate lipid. Their oxygen consumption rate again increased when they were allowed to resume feeding. Therefore, food limitation induced quiescence in the adult. On the other hand, diapause was induced by short daylength (critical photoperiod was 12L:12D), leading to immature ovaries, hypertrophied fat bodies, lipid accumulation and low oxygen consumption rate even when food was available. However, in the study area most of the bugs probably did not enter diapause at any time of the year, because the shortest outdoor daylength including civil twilight was longer than the critical daylength for diapause induction.
Interspecific competition between Eupelmus vuilleti and Dinarmus basalis, two solitary ectoparasitoids of Bruchidae larvae and pupae
Authors: van Alebeek F. A. N. , Rojas‐Rousse D. , Leveque L.
Published: April 2011

Coexistence of two solitary ectoparasitoids of bruchids may be the result of counter‐balanced competition. Some strategies in interspecific competition at the extrinsic level of female behaviour are identified. Dinarmus basalis (Rondani) (Hymenoptera; Pteromalidae) has adapted an evasion strategy to avoid competition. Females of D. basalis show interspecific discrimination against hosts parasitized by Eupelmus vuilleti Crawford (Hymenoptera; Eupelmidae) and lay fewer eggs in the presence of females or hosts parasitized by the latter. Eupelmus vuilleti has adapted an aggressive strategy. In contrast to D. basalis, E. vuilleti concentrates her ovipositions on hosts already parasitized by D. basalis. Females of E. vuilleti preferably use oviposition holes made by other parasitoids, and are able to kill eggs and larvae of D. basalis selectively by thrusts of their ovipositor (ovicide and larvicide). Furthermore, E. vuilleti can act as a facultative hyperparasitoid on older larvae of D. basalis. The number of E. vuilleti offspring is not affected by the presence of D. basalis on a host. Our study does not provide insight in the process of larval competition.

Compétition interspécifique entre Eupelmus vuilleti et Dinarmus basalis, deux ectoparasitoïdes solitaires des stades larvaires et nymphaux de Bruchidae

La coexistence de deux ectoparasitoïdes solitaires de Bruchidés peut resulter de compétition contrebalancée (Zwölfer, 1971). Quelques stratégies en situation de compétition interspécifique ont été identifiées au niveau (extrinsèque) du comportement de femelles. Dinarmus basalis (Rondani) (Hymenoptera; Pteromalidae) a développé une stratégie d'évitement de la compétition. Les femelles de D. basalis montrent une capacité à reconnaître les hôtes parasités par Eupelmus vuilleti Crawford (Hymenoptera; Eupelmidae), et pondent moins d'œufs en présence des femelles d'E. vuilleti ou des hôtes parsités par cette espèce. Eupelmus vuilleti a adapté une stratégie aggressive. Au contraire de D. basalis, E. vuilleti concentre sa ponte sur les hôtes déjà parasités par D. basalis. Les femelles d'E. vuilleti utilisent préférentiellement les orifices de ponte pratiqués par les autres parasitoïdes. Elles sont alors capables de tuer grace à l'ovipositeur les œufs et les larves de D. basalis (ovicide et larvicide). De plus, E. vuilleti est capable d'hyperparasiter les larves de dernier stade de D. basalis. Le nombre de descendants d'E. vuilleti n'est pas affecté par la présence de D. basalis sur un hôte. Notre étude expérimentale n'a pas permis l'étude du mécanisme de la compétition larvaire.
Control of diapause and supercooling by the retrocerebral complex in Pyrrhocoris apterus
Authors: Hodkova Magdalena , Hodek Ivo
Published: April 2011

Effects of external (photoperiod, temperature) and internal (retrocerebral complex, diapause condition) factors on supercooling were studied in Pyrrhocoris apterus (L.) (Heteroptera: Pyrrhocoridae) adults. An increase in supercooling capacity is associated with the induction of diapause by short‐day photoperiod or cardiacallatectomy of long‐day non‐diapause insects in spite of a high temperature of 26 °C. The induction of diapause is a prerequisite for a further increase in supercooling capacity by cold acclimation.

Post‐diapause adults show low values of the supercooling point also in late January or early February, although their developmental potential is fully restored. Evidently the ability to supercool associated with diapause induction is maintained by a low ambient temperature in spite of diapause termination. The supercooling point increases rapidly when these adults are transferred to a high temperature of 26 °C and cold re‐acclimation is then no longer possible. The inhibition of morphogenesis (maturation of gonads) by cardiacallatectomy does not prevent the supercooling point from increasing in post‐diapause adults at the high temperature.
Trichogramma egg parasitism of Helicoverpa armigera on short‐duration pigeonpea intercultured with sorghum
Authors: Duffield S. J.
Published: April 2011

The levels of egg parasitism by Trichogramma spp. (Hymenoptera: Trichogrammatidae) on populations of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) were recorded on sorghum (Sorghum bicolor L.) and on two flushes of flowers on short‐duration pigeonpea (Cajanus cajan L.). H. armigera oviposition was concentrated on the early flowering stage of sorghum and the flowering and early podding stages of both flushes of pigeonpea. Parasitism on sorghum increased rapidly as egg density increased and reached a peak of 74.6%. Parasitism on pigeonpea was concentrated on H. armigera eggs laid on the first flush of pigeonpea flowers with a maximum of 69.2%. These high levels of parasitism on pigeonpea coincided with the period of parasite activity on sorghum. The levels of parasitism then declined rapidly and only very low levels were detected on a second flush of flowers. This rapid decline resulted in the overall egg mortality caused by Trichogramma on pigeonpea to be low, with a maximum of 7.8% caused by parasitism, compared to 34.4% on sorghum. The pattern of parasitism suggests that a transfer of parasites occurred from sorghum to pigeonpea. The rapid decline of parasitism on the pigeonpea indicates that parasite populations cannot be sustained on pigeonpea once the influx from sorghum stops. The results are discussed in terms of a possible method of encouraging the transfer of parasites from sorghum to short‐duration pigeonpea by producing a more continuous cropping environment.
Responses of the sheep blowfly Lucilia sericata to carrion odour and carbon dioxide
Authors: Wall R. , Warnes M.L.
Published: April 2011

The nature of the responses of the sheep blowfly Lucilia sericata Meigen (Diptera: Calliphoridae) to carrion odours and carbon dioxide were examined in a windtunnel in the laboratory and the attractiveness of carrion‐bait was examined in the field. In the wind tunnel, gravid 9‐day‐old females increased both the number and duration of their flights, in response to carrion odours. In addition, linear velocity was reduced and the sinuosity of flight increased in the presence of these odours. With 3‐day‐old females, the response to carrrion odour depended on previous exposure to proteinaceous material. Protein deprived females showed kinetic responses to carrionodour which were similar to those of gravid females. No such changes were observed in protein‐fed females. No responses to CO2 were observed. In the field, the importance of olfactory cues in bait location was demonstrated by the absence of L. sericata from sticky targets lacking an odour bait. Increased bait concentration did not affect the age, sex ratio or ratio of L. sericata to other Lucilia spp. caught, but did increase the numbers caught. Analysis of the reproductive status of females caught, indicated that a greater number of gravid females were caught than expected, while a lower number of females in the final stages of vitellogenesis were caught than expected. The results show that the responses of L. sericata to odours are complex, and are dependent on both exogenous and endogenous stimuli, the latter including the stage of ovarian development.
Effect of trap background on cabbage root fly landing and capture
Authors: Finch S.
Published: April 2011

Pieces (600 mm × 800 mm) of coloured board, plastic sheeting and woven materials, placed beneath water traps prevented the traps from becoming soiled during rainy weather. Such backgrounds are not recommended for use with traps for monitoring populations of the cabbage root fly (Delia radicum L. ‐ Diptera:Anthomyiidae), however, as, instead of increasing trap catch they reduced the numbers of female flies caught by 70%–90%. The main effect was that the visually attractive stimuli from the introduced backgrounds competed with those from the trap. A white background competed with a white trap on a direct fly/unit area basis. Green backgrounds stimulated males to land and the vertical stems of both real and artificial grass induced trivial flights that resulted in greater numbers of males entering traps resting on short grass. Most females were caught over bare soil. To minimize the variation in catch between traps used for monitoring cabbage root fly populations, the background beneath each trap should be similar. For maximum capture, the background should be of grass for male flies and of bare soil for female flies. Care is required if data from traps within mulched crops are used to make pest control decisions, as they will underestimate considerably the numbers of flies in such crops.
Spectral reflectance from a broccoli crop with vegetation or soil as background: influence on immigration by Brevicoryne brassicae and Myzus persicae
Authors: Costello Michael J.
Published: April 2011

Light reflectance in five wavebands of the spectrum was measured from broccoli (Brassicae oleracea var. botrytis [L].) interplanted with leguminous cover crops (cover crop background) or broccoli grown as monoculture (bare soil background), and fertilized with compost or synthetic fertilizer. Alate Brevicoryne brassicae (L.) and Myzus persicae (Sulzer) (Homoptera: Aphididae) were monitored in yellow pan water traps and on broccoli leaves. Reflectance intensity was higher with a background of bare soil at all wavebands except blue (400–455 nm) in the early‐season. Intensity decreased as broccoli canopy cover increased at all wavebands except blue and green (515–550 nm), declining‐most dramatically in the yellow (550–590 nm). Highest late‐season intensities were in plots with bare soil background and fertilized with compost (those stressed for nitrogen). Few differences in spectral composition, expressed for each waveband as a percentage of total intensity, were recorded. Numbers of alatae were lowest in cover crop background plots in the early season, reached equivalency with bare soil background by mid‐season, and showed highest positive correlations with intensity in the yellow (550–590 nm). Results correspond to laboratory findings that aphids are attracted to higher intensity light, especially in the yellow waveband, and support a phototactic explanation for aphid orientation in the field.
Within‐patch foraging behaviour of the aphid parasitoid Aphidius funebris: plant architecture, host behaviour, and individual variation
Authors: Weisser Wolfgang W.
Published: April 2011

The influence of plant architecture, host colony size, and host colony structure on the foraging behaviour of the aphid parasitoid Aphidius funebris Mackauer (Hymenoptera: Aphidiidae) was investigated using a factorial experimental design. The factorial design involved releasing individual parasitoid females in aphid colonies consisting of either 10 or 20 individuals of Uroleucon jaceae L. (Homoptera: Aphididae) of either only larval instar L3 or a mixture of host instars, both on unmanipulated plants and on plants that had all leaves adjacent to the colony removed. Interactions between the parasitoid and its host were recorded until the parasitoid had left the plant. The time females spent on the host plant and the number of eggs laid varied greatly among females. Host colony size significantly affected patch residence time and the number of contacts between parasitoids and aphids. Plant architecture influenced the time‐budget of the parasitoids which used leaves adjacent to the aphid colony for attacking aphids. Female oviposition rate was higher on unmanipulated plants than on manipulated plants. No further significant treatment effects on patch residence time, the number of contacts, attacks or ovipositions were found. Oviposition success of A. funebris was influenced by instar‐specific host behaviour. Several rules‐of‐thumb proposed by foraging theory did not account for parasitoid patch‐leaving behaviour.
The effects of a phagostimulant and a deterrent on the microstructure of feeding by Manduca sexta caterpillars*
Authors: Bowdan E.
Published: April 2011

Caterpillars of the hawkmoth Manduca sexta Johan. (Lepidoptera: Sphingidae) were offered discs of agar containing one of a range of concentrations of sucrose or of quinine, and the microstructure of the resulting feeding behaviour was quantified. As sucrose concentration increased caterpillars ate more by increasing the rate of biting and the lengths of meals. Bite frequency increased, after a latency of seconds to minutes, over the entire range tested (0.005 M to 0.5 M) whereas meal length reached a maximum at 0.1 M. Larvae spent less time feeding on agar containing 1 mM quinine than on quinine‐free agar. This was accomplished by a reduction in the size of meals; numbers of chewing bouts in meals were lower. No other feeding behaviours were affected. In addition there was no orderly relationship between quinine concentration and changes in feeding behaviours. These observations suggested that postingestive effects were important in decreasing feeding.
Estimating animal behavior and residency from movement data
Authors: Pedersen M. W. , Patterson T. A. , Thygesen U. H. , Madsen H.
Published: April 2011

We present a process‐based approach to estimate residency and behavior from uncertain and temporally correlated movement data collected with electronic tags. The estimation problem is formulated as a hidden Markov model (HMM) on a spatial grid in continuous time, which allows straightforward implementation of barriers to movement. Using the grid to explicitly resolve space, location estimation can be supplemented by or based entirely on environmental data (e.g. temperature, daylight). The HMM method can therefore analyze any type of electronic tag data. The HMM computes the joint posterior probability distribution of location and behavior at each point in time. With this, the behavioral state of the animal can be associated to regions in space, thus revealing migration corridors and residence areas. We demonstrate the inferential potential of the method by analyzing satellite‐linked archival tag data from a southern bluefin tunaThunnus maccoyiiwhere longitudinal coordinates inferred from daylight are supplemented by latitudinal information in recorded sea surface temperatures.
Modeling of tunneling through a three-layer gate stack with/without a quantum well
Authors: Mazurak A. , Walczak J. , Majkusiak B.
Published: April 2011

Accurate analytical formulas for tunneling probability through a three-layer gate stack with semiconductor/metallic quantum well or without a quantum well were derived. For the case of a three-barrier stack (no quantum well) the authors derived a simplified analytical Wentzel–Krammers–Brillouin equivalent formula, which was generalized for the case of an n-barrier stack. The tunneling through a three-layer stack with a quantum well was considered. The effect of scattering on tunneling probability and current-voltage characteristics of the double-barrier metal-oxide-semiconductor system was investigated.
GLOBAL ANALYSIS AND CHAOTIC DYNAMICS OF SIX-DIMENSIONAL NONLINEAR SYSTEM FOR AN AXIALLY MOVING VISCOELASTIC BELT
Authors: ZHANG W. , GAO M. J. , YAO M. H.
Published: April 2011

An analysis on the chaotic dynamics of a six-dimensional nonlinear system which represents the averaged equation of an axially moving viscoelastic belt is given in this paper for the first time. We combine the theory of normal form and the global perturbation method to investigate the global bifurcations and chaotic dynamics of the axially moving viscoelastic belt. Firstly, the theory of normal form is used to reduce six-dimensional averaged equation to the simpler normal form. Then, the global perturbation method is employed to analyze the global bifurcations and chaotic dynamics of six-dimensional nonlinear system. The analysis results indicate that there exist the homoclinic bifurcations and the single-pulse in six-dimensional averaged equation. Finally, numerical simulations are also used to investigate the nonlinear dynamic characteristics of the axially moving viscoelastic belt. The results of numerical simulations demonstrate that there exist the chaotic motions and the jumping orbits of the axially moving viscoelastic belt.
A HIERARCHY OF LIOUVILLE INTEGRABLE LATTICE EQUATION ASSOCIATED WITH A THREE-BY-THREE DISCRETE SPECTRAL PROBLEM AND ITS INFINITELY MANY CONSERVATION LAWS
Authors: LI YU-QING , XU XI-XIANG
Published: April 2011

A discrete three-by-three matrix spectral problem is put forward and the corresponding discrete soliton equations are deduced. By means of the trace identity the Hamiltonian structures of the resulting equations are constructed, and furthermore, infinitely many conservation laws of the corresponding lattice system are obtained by a direct way.
ROBUST SYNCHRONIZATION WITH UNIFORM ULTIMATE BOUND BETWEEN TWO DIFFERENT CHAOTIC SYSTEMS WITH UNCERTAINTIES
Authors: CAI JIANPING , YUAN ZHENGZHONG
Published: April 2011

Adaptive controllers are designed to synchronize two different chaotic systems with uncertainties, including unknown parameters, internal and external perturbations. Lyapunov stability theory is applied to prove that under some conditions the drive-response systems can achieve synchronization with uniform ultimate bound even though the bounds of uncertainties are not known exactly in advance. The designed controllers contain only feedback terms and partial nonlinear terms of the systems, and they are easy to implement in practice. The Lorenz system and Chen system are chosen as the illustrative example to verify the validity of the proposed method. Simulation results also show that the present control has good robustness against different kinds of disturbances.
STUDY OF THE MICRO-STRUCTURE OF PtxSi ULTRA-THIN FILM
Authors: LIU SHUANG , FALCO CHARLES M. , ZHONG ZHIYONG
Published: April 2011

Ultra-thin platinum (Pt) films were deposited on Si (100) substrates at 160°C by magnetron sputtering and subsequently annealed to form silicides. The thickness of the Pt x Si films was found to be approximately 4 nm as determined by transmission electron microscopy (TEM). X-ray photoelectron spectroscopy (XPS) analysis shows that these films consist of PtSi and Pt 2 Si phases, and a multi-layer configuration of SiO x/ PtSi/Pt 2 Si/Si was detected by angle-resolved XPS. However, the Pt 3 Si phase was not detected by X-ray diffraction (XRD).
ON SOLVABLE SUBGROUPS OF AUTOMORPHISM GROUPS OF RIGHT-ANGLED ARTIN GROUPS
Authors: DAY MATTHEW B.
Published: April 2011

For any right-angled Artin group, we show that its outer automorphism group contains either a finite-index nilpotent subgroup or a nonabelian free subgroup. This is a weak Tits alternative theorem. We find a criterion on the defining graph that determines which case holds. We also consider some examples of solvable subgroups, including one that is not virtually nilpotent and is embedded in a non-obvious way.
ON PROFINITE UNIFORM STRUCTURES DEFINED BY VARIETIES OF FINITE MONOIDS
Authors: PIN JEAN-ÉRIC , SILVA PEDRO V.
Published: April 2011

We consider uniformities associated with a variety of finite monoids V, but we work with arbitrary monoids and not only with free or free profinite monoids. The aim of this paper is to address two general questions on these uniform structures and a few more specialized ones. A first question is whether these uniformities can be defined by a metric or a pseudometric. The second question is the description of continous and uniformly continuous functions. We first give a characterization of these functions in term of recognizable sets and use it to extend a result of Reutenauer and Schützenberger on continuous functions for the pro-group topology. Next we introduce the notion of hereditary continuity and discuss the behaviour of our three main properties (continuity, uniform continuity, hereditary continuity) under composition, product or exponential. In the last section, we analyze the properties of V-uniform continuity when V is the intersection or the join of a family of varieties and we discuss in some detail the case where V is commutative.
SEQUENTIAL LINEAR NEIGHBORHOOD PROPAGATION FOR SEMI-SUPERVISED PROTEIN FUNCTION PREDICTION
Authors: WANG JINGYAN , LI YONGPING
Published: April 2011

Predicting protein function is one of the most challenging problems of the post-genomic era. The development of experimental methods for genome scale analysis of molecular interaction networks has provided new approaches to inferring protein function. In this paper we introduce a new graph-based semi-supervised classification algorithm Sequential Linear Neighborhood Propagation (SLNP), which addresses the problem of the classification of partially labeled protein interaction networks. The proposed SLNP first constructs a sequence of node sets according to their shortest distance to the labeled nodes, and then predicts the function of the unlabel proteins from the set closer to labeled one, using Linear Neighborhood Propagation. Its performance is assessed on the Saccharomyces cerevisiae PPI network data sets, with good results compared with three current state-of-the-art algorithms, especially in settings where only a small fraction of the proteins are labeled.
Comparison of PMAC Machines for Starter-Generator Application in a Series Hybrid-Electric Bus
Authors: Jurkovic Sinisa , Strangas Elias G.
Published: April 2011

This paper presents a comparative study of outer rotor PMAC machine candidates for starter-generator application in hybrid bus with series power train configuration. PMAC machines with interior and surface mount permanent
magnets are considered and compared, although a complete analysis is only carried out for the SPM. Different design aspects
such as concentrated versus distributed windings as well as interior and exterior rotor structures are evaluated. Different
slot numbers per pole per phase configurations for concentrated winding PMAC machines are also examined. Comparison and
evaluation of the machines is based on their performance which included evaluation of winding and iron losses, magnet losses, and
maximum torque capability as well as the size and weight of the machines.
Molecular Nevogenesis
Authors: Ross Andrew L. , Sanchez Margaret I. , Grichnik James M.
Published: April 2011

Despite recent advances, the biology underlying nevogenesis remains unclear. Activating mutations in NRAS, HRAS, BRAF, and GNAQ have been identified in benign nevi. Their presence roughly correlates with congenital, Spitz, acquired, and blue nevi, respectively. These mutations are likely to play a critical role in driving nevogenesis. While each mutation is able to activate the MAP kinase pathway, they also interact with a host of different proteins in other pathways. The different melanocytic developmental pathways activated by each mutation cause the cells to migrate, proliferate, and differentiate to different extents within the skin. This causes each mutation to give rise to a characteristic growth pattern. The exact location and differentiation state of the cell of origin for benign moles remains to be discovered. Further research is necessary to fully understand nevus development given that most of the same developmental pathways are also present in melanoma.
Impact of High-Dose Atorvastatin on Endothelial, Platelet, and Angiogenic Indices
Authors: Jaumdally Rumi J. , Lip Gregory Y. H. , Varma Chetan , Blann Andrew D.
Published: April 2011

Lipid lowering with statins improves morbidity and mortality, particularly in diabetics, and may have additional nonlipid effects. South Asians (SAs) are at higher risk of cardiovascular disease and diabetes compared with white Europeans (WEs). We hypothesized that abnormal endothelial (marked by von Willebrand factor), angiogenesis (VEGF, angiopoietins 1 and 2) and platelet function (soluble P selectin, soluble CD40L) improve with statin treatment in diabetics in different ethnic groups. Plasma was obtained before and 8 weeks after treatment with atorvastatin (80 mg/day) by SAs and WEs with or without diabetes. Research indices were measured by enzyme-linked-immunosorbent assay (ELISA). Treatment increased angiopoietin-2 ( P < .04) in all groups regardless of diabetes or ethnicity. In those free of diabetes, angiopoietin-2 increased 3-fold, whereas in diabetes, it increased 2-fold. We suggest that an additional effect of statins is to increase levels of growth factor angiopoietin-2 in the direction of normality. This effect is weaker in participants with diabetes.
The Effective Friction Coefficient of a Laminate Composite, and Analysis of Pin-Loaded Plates
Authors: Xiao Yl , Wang Wen-Xue , Takao Yoshihiro , Ishikawa Takashi
Published: April 2011

A calculation method based on M-CLT (Modified Classical Lamination Theory) for the friction coefficient of a CFRP (Carbon Fiber Reinforced Plastic) composite laminate edge is proposed. It is derived based on experimental friction coefficients in unidirectional off-axis laminae and a high-order algebraic equation from a numerical solution to the specific boundary for the frictional contact problem. A numerical experiment of a frictional contact problem is also performed by means of a nonlinear three-dimensional finite element analysis and the results are compared with those obtained from the M-CLT method for various contact directions. Good agreement is found between the two sets of results. Finally, the friction coefficient derived by using the M-CLT method is applied to a two-dimensional contact stress analysis of a pin-loaded composite laminate. The effects of the method used to calculate the friction coefficient on the contact stress distribution are investigated.
Interface Failure at Ply Drops in CFRP/Sandwich Panels
Authors: Thomsen O. T. , Mortensen F. , Frostig Y.
Published: April 2011

This paper presents the results of an investigation of delamination failure at "exterior" ply drops in tension loaded sandwich panels with laminated composite face sheets. The thickness of composite laminates used as face sheets of sandwich panels is often increased locally around highly loaded locations such as joints, rivets, bolts or inserts. At the stations where such ply drops are made, the local bending stiffness of the face sheet laminates change discontinuously, thus inducing severe local bending effects. These local bending effects induce severe stress concentrations in the interfaces between the dropped plies/sub-laminates and the remaining face sheet laminates, and this may initiate delamination failure. The present paper suggests a simple approach for stress analysis and a simple "characteristic length" stress criterion for the prediction of delamination failure. An experimental investigation has been carried out, and the measured delamination loads compare well the theoretical predictions.
On Thermoelastic and Hygrometric Response of Sandwich Beams with Laminate Facings and Honeycomb Cores: Part IV—A Dynamic Theory
Authors: Mukhopadhyay Achintya K. , Sierakowski Robert L.
Published: April 2011

The systematic development of a dynamic theory for a sandwich beam is presented leading to the governing equations of equilibrium and the natural boundary conditions. Using Timoshenko beam theory [I], a function 1' is introduced in terms of the kinetic and strain energies of the system consisting of both laminate facings and honeycomb core. Reissner's variational theorem is used in conjunction with Hamilton's principle in order to obtain a new set of governing equations of motion, which is accomplished by letting the variation of D vanish. In addition, the natural boundary conditions are obtained in the process of the development of the theory. The constitutive equations for the beam are recovered as an outcome of the variational analysis. The static equations of equilibrium are obtained as a special case.
Prediction of Failure in Unsaturated Polyester Reinforced by Plain Weave Glass Fabric
Authors: Nguyen-Hoa H. , Vu-Khanh T.
Published: April 2011

Polyester/glass fiber is probably by far the most commonly used composite. This paper presents the results of an investigation on the failure of this composite made with a plain weave glass fabric. A recently proposed sub-plies model is utilized to predict the failure strengths of the fabric composite after shear deformation of the interlaced yarns, induced by the forming process. A procedure for the determination of the equivalent on-axis tensile and compressive strengths of the constituent plies is also proposed to take into account the fiber undulation effect on strength performance. The predicted compressive and tensile strengths are compared with experimental measurement as a function of the deformation angle of the interlaced yarns. Furthermore, the onset of damage is also compared with the initial failure predicted by the sub-plies model. The predicted results are in good agreement with the experimental data.
Oxidation Assessment of Highly Inhibited SiC Coated Carbon-Carbon Laminates Using Electrical Resistance Measurements
Authors: Parker Paul A. , Ochoa Ozden O.
Published: April 2011

The impact of oxidation on shear modulus, mass loss, and electrical resistance of carbon-carbon laminates at 900°C is studied. This approach is unique in relating in-situ measured physical properties to mechanical properties at high temperature oxidative environment. The goal is to understand the relationship between the changes observed in the shear modulus and electrical resistance in relation to mass loss. In-situ electrical resistance measurements were taken at 900°C and shear modulus measurements were taken at room temperature prior to and following oxidation. The results reveal that the electrical resistance, shear modulus, and mass loss are not independent of each other; as oxidation time increases, mass loss and electrical resistance increase whereas the shear modulus decreases. A simple analytical model is developed for electrical resistance simulation and is correlated to shear modulus within 5% of experimental observations.
Application of Tsai-Wu Criterion to Notched and Unnotched Composite Laminates under Torque Loading
Authors: Gong X. Lu , Gong X. J. , Laksimi A. , Benzeggagh M. L.
Published: April 2011

This work deals with the behaviour of composite laminates under static torque loading. The stress distributions in notched and unnotched unidirectional composite laminates based on an analytical study and a finite element calculation are discussed. The Tsai-Wu failure criterion is applied locally in three-dimensions to predict the initiation of damage and sites of local failure are detected by in-situ observations of the fracture surfaces in the scanning electron microscope (SEM) that confirm this prediction. With the help of the schematic model of acoustic emission, each type of damage mechanism and their development process during twisting are described empirically and phenomenologically. These investigations give a better understanding of the damage process and provide useful information in establishing quantitative representation, including the controlling factors and mechanisms for composite laminates subjected to torsion.
Simulation and Experimental Investigation of Impact Damage in Composite Plates with Holes
Authors: Green E. R. , Morrison C. J. , Luo R. K.
Published: April 2011

A number of authors have carried out finite element simulations of the damage produced in fibre composite laminates by medium and high velocity impacts, with results which generally show good agreement with experimental evidence. In some engineering applications, these laminates may be constructed with pre-existing holes or cut-outs whose presence may significantly affect the nature of the impact damage. As far as is known, no study of this problem has appeared in the literature and this paper reports the first results of an experimental and simulation exercise to determine the additional damage arising from the presence of holes. The experimental evidence shows that the holes can induce matrix cracking in the lower lamina which is additional to that arising in the laminate without holes. These matrix cracks can extend from the region directly below the impact to the edge of the holes and in some circumstances further cracks can emanate from the far side of the holes. The simulation predicts that the presence of the holes can give rise to multiple cracks directly below the impact region which spread towards but not up to the holes, together with a crack emanating from the hole towards the impact region. Thus, whilst the computations are in qualitative agreement with the experimental evidence there is a need for further work in order to improve on the predictions.
The Effect of Phenylethynyl Terminated Imide Oligomer Molecular Weight on the Properties of Composites
Authors: Smith J. G. , Connell J. W. , Hergenrother P. M.
Published: April 2011

As part of a program to develop high temperature/high performance structural resins for applications on a Mach 2.4 high speed civil transport, a phenylethynyl terminated imide oligomer designated PETI-5 has been under investigation. The oligomer was prepared at a calculated number average molecular weight of about 5000 g/mol and has exhibited good processability and excellent mechanical properties upon thermal cure at 350-371°C for 1 hr. However in the fabrication of complex composite structures, primarily skin stringer structure, a resin with improved flow and equivalent or better mechanical properties was desired. To improve melt flow (i.e., processability or compression moldability), 1250 and 2500 g/mol molecular weight versions of PETI-5 were prepared and their solutions used to prepare supported adhesive film and unidirectional carbon fiber prepreg. Imide powder of the oligomers was used for characterization of melt flow behavior and the fabrication of neat resin moldings. The PETI-5 oligomers were fabricated into titanium adhesive specimens and IM-7 carbon fiber laminates under 0.3-1.4 MPa for 1 hr at 350-371°C. The lower molecular weight oligomers exhibited improved processability, and when cured, higher T g s and better retention of mechanical properties at elevated temperature without significantly sacrificing toughness (damage tolerance) than the higher molecular weight oligomer. The neat resin, adhesive and composite properties of the cured polymers are discussed.
Mechanical and Impact Properties of Needle Punched Nonwoven Composites
Authors: Lee Sung Ho , Kang Tae Jin
Published: April 2011

The effect of changes in fiber structure on the mechanical properties of nonwoven composite with different punching densities was studied through the testing of tensile, bending, impact, compression after impact, fatigue, friction/wear and mode-I interlaminar fracture properties.

The tensile strength and mode-I interlaminar fracture toughness of nonwoven composite was increased with increasing punching densities due to the increased fiber entanglement. The flexural, impact, fatigue and wear properties were decreased with punching densities due to the damage to fibers during the punching process which resulted in the reduction of fiber length. The impact resistant properties showed its maximum at the punching density of 30 penetrations/cm2. The tensile modulus and the compression strength were determined from the orientation of the reinforcing fibers which was affected with the punching densities. The mechanical properties of nonwoven composite showed rather isotropic properties with increased random distribution of the fibers at high punching densities. In the range of adequate punching densities, the nonwoven composite showed substantially improved mechanical and impact properties compared to the woven laminate composite. The nonwoven composite showed improved properties of flexural and compression strengths as well as mode-I interlaminar fracture toughness.
Fatigue Response and Modelling of Variable Stress Amplitude and Frequency in AS-4/PEEK Composite Laminates, Part 1: Experiments
Authors: Lee C. H. , Jen M. H. R.
Published: April 2011

This paper aims to investigate the tension-tension (T-T) fatigue behavior at variable fatigue loadings in AS-4/PEEK composite laminates. Three lay-ups of specimens, such as cross-ply [0/90]4s, quasi-isotropic [0/45/90/-45]2s and angle-ply [±45]4s, were tested at room temperature and moisture. The parameters involved were maximum stress (low and high), frequency (5 Hz and 25 Hz), and stress ratio (R = 0 and 0.2). We received the fatigue life and found that the maximum stress and stress ratio are the two controlling factors on lives, whilst frequency affects significantly in [±45]4s laminates. Next, stiffness and strength degradation were defined to describe the laminate damage process due to cyclic loadings and these experimental data were correlated with suitable models proposed in power function form. From the damage curves we observe that three stages of damage growth can be clearly divided and different failure mechanisms exist among three lay-ups. All these valuable data will be used to predict fatigue life under multi-block cyclic loadings in association with Cumulative Damage Theory in Part 2: Analysis and Formulation.
Fatigue Response and Modelling of Variable Stress Amplitude and Frequency in AS-4/PEEK Composite Laminates, Part 2: Analysis and Formulation
Authors: Lee C. H. , Jen M. H. R.
Published: April 2011

The tension-tension fatigue features at variable cyclic loadings in APC-2 composite laminates of three lay-ups, including cross-ply [0/90]4 s, quasi-isotropic [0/45/90/−45]2 s and angle-ply [±45]4 s, were investigated. The parameters involved are maximum stress, frequency, and stress ratio. First, the fatigue tests of two-step and multi-block loadings were accomplished. Next, based on Marco-Starkey cumulative damage theory, we proposed the nonlinear cumulative damage theory and nonlinear reduced undamage theory associated with damage parameters in Part 1 and developed the well-established fatigue failure criterion of multi-block loading to predict the life due to variable fatigue loadings. The difference of cycle fraction between two damage loading conditions was obtained, so that we could easily shift to different damage curve and predicted the life due to multi-block fatigue loading. The measured lives in glass/epoxy and carbon/PEEK composites are found well close to those predicted by our proposed models.
Effective Elastic Constants of Bidirectional Laminates Containing Transverse Ply Cracks
Authors: Whitney James M.
Published: April 2011

All nine independent effective elastic constants of [0° m/90° n] S laminates containing transverse cracks through the middle 90° n layers are determined analytically. The cracks are assumed to be evenly spaced and to extend across the entire laminate width. Each of the 0° m and 90° n ply clusters are modeled as homogeneous, orthotropic materials with the layers connected through continuity of displacements and tractions at the ply interfaces. A stress based homogeneous plate theory which includes the effect of transverse shear and normal stresses is utilized to model the ply clusters. Elastic moduli and stress distributions are compared to shear lag and other analytical models existing in the literature. Moduli of a [±45°] S laminate containing a crack parallel to the fibers in the middle plies are obtained by a rotation of elastic properties obtained from a cracked [0°/90°] S laminate.
A Numerical Study of Nonisothermal Resin Flow in RTM with Heated Uniaxial Fibers
Authors: Wymer Scott A. , Engel Renata S.
Published: April 2011

A numerical model is developed to study the flow of a thermoset resin parallel to a unidirectional, heated fiber array, where the resin viscosity varies with temperature. Steady, incompressible flow is assumed when solving the momentum equation for the velocity parallel to the fiber tow. Resin temperatures are determined by applying a finite differencing scheme to the convective energy equation. An iterative approach is used to update the velocity, temperature, and viscosity in the flow direction. The resulting nonisothermal flow profiles are 'plug-like" with significant increases in the velocities near the fibers. Comparisons of average total flow times for isothermal and nonisothermal flows indicate that, for an epoxy resin at an initial 250C and the fibers heated to 100°C. the fill time is equivalent to the isothermal case with the resin held at a constant 50°C.
A Model for the Compressive Failure of Composite Materials
Authors: Williams Todd O. , Cairns Douglas S.
Published: April 2011

A theoretical model for the failure of a fiber/ply due to compressive loading is developed. The formulation examines the case of a dilute solution composed of a single fiber/ply embedded in an infinite plane of matrix material. This work is based on a two-dimensional analysis of a fiber/ply with or without some initial imperfection. The model analyzes the transverse displacement of the fiber/ply and the corresponding effect on the stress state of the various phases. The solution allows the possibility of interfacial failure of the composite system, as well as microbuckling of the fiber. In the interfacial failure mode, the model allows interactive effects between shearing and debonding contribute to failure. The interfacial failure criteria is based on a combined stress failure criteria for the resultant stresses at the fiber/matrix interface. The analytical results for both the fiber and ply cases are compared to experimental data and generally show excellent agreement. The results show that buckling, especially for small imperfections, is a theoretical upper bound for failure. In addition, the results indicate that interface failure instability (IFI) occurs at much lower stresses than microbuckling for typical fiber reinforced polymers.