bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates
Authors: Amiot Romain , Wang Xu , Zhou Zhonghe , Wang Xiaolin , Buffetaut Eric , Lécuyer Christophe , Ding Zhongli , Fluteau Frédéric , Hibino Tsuyoshi , Kusuhashi Nao , Mo Jinyou , Suteethorn Varavudh , Wang Yuanqing , Xu Xing , Zhang Fusong
Published: March 2011

Early Cretaceous vertebrate assemblages from East Asia and particularly the Jehol Biota of northeastern China flourished during a period of highly debated climatic history. While the unique characters of these continental faunas have been the subject of various speculations about their biogeographic history, little attention has been paid to their possible climatic causes. Here we address this question using the oxygen isotope composition of apatite phosphate (δ) from various reptile remains recovered from China, Thailand, and Japan. δvalues indicate that cold terrestrial climates prevailed at least in this part of Asia during the Barremian—early Albian interval. Estimated mean air temperatures of about 10 ± 4 °C at midlatitudes (∼42 °N) correspond to present day cool temperate climatic conditions. Such low temperatures are in agreement with previous reports of cold marine temperatures during this part of the Early Cretaceous, as well as with the widespread occurrence of the temperate fossil wood genusXenoxylonand the absence of thermophilic reptiles such as crocodilians in northeastern China. The unique character of the Jehol Biota is thus not only the result of its evolutionary and biogeographical history but is also due to rather cold local climatic conditions linked to the paleolatitudinal position of northeastern China and global icehouse climates that prevailed during this part of the Early Cretaceous.
Bionomics and polymorphism in Callosobruchus subinnotatus (Coleoptera: Bruchidae)
Authors: Appleby J.H. , Credland P.F.
Published: March 2011

Callosobruchus subinnotatus (Pic) is the major insect pest of stored bambara groundnuts, Vigna subterranea (L.) Verdcourt, in sub-Saharan West Africa, but little is currently known about its biology or how it may be controlled. A series of laboratory studies was performed to investigate the bionomics of and differences between two apparently different morphs of adult of each sex of this species, here termed ‘active’ and ‘normal’. Major differences in their morphology, physiology and behaviour were identified and are described in detail for the first time. They provide clear evidence of the existence of an adult polymorphism among populations of this species, which is comparable in certain respects to that previously described for C. maculatus (Fabricius) and C. chinensis Linnaeus. Adults can be separated into the correct morph based on characteristic differences in elytral and pygidial colour and pattern. ‘Normal’ adults are characterized by having high fecundity, short adult life and are relatively sedentary while ‘active’ adults exhibit reproductive diapause (suspension of reproductive activity), are long lived, and show (at least in females) increased dispersal tendencies. These characteristics suggest adaptation of the ‘active’and ‘normal’ morphs respectively to the different environments of field and seed stores, and the significance of the polymorphism in the life history of C. subinnotatus is discussed in this context. The design of any effective control regime for this bruchid needs to take account of and could potentially be based upon the existence of polymorphism in C. subinnotatus.
A shoot-fly Atherigona tritici sp. n. (Diptera: Muscidae), attacking wheat Triticum aestivum in Egypt
Authors: Pont A.C. , Deeming J.C.
Published: March 2011

The two ‘forms’ of the Afrotropical shoot-fly Atherigona rubricornis Stein are shown to be good species. A neotype is designated for the true A. rubricornis, which is restricted to tropical Africa. The other form is described as A. triticisp. n. It is widespread in tropical Africa, but is known also from Egypt, where the larvae attack wheat seedlings, Israel and Yemen. Infestation levels of larvae, with maxima between 9% and 32%, indicate that it is a significant pest of wheat seedlings in Egypt.
The effect of natural enemies on the spread of barley yellow dwarf virus (BYDV) by Rhopalosiphum padi (Hemiptera: Aphididae)
Authors: Smyrnioudis I.N. , Harrington R. , Clark S.J. , Katis N.
Published: March 2011

The effects of two natural aphid enemies, adult Coccinella septempunctataLinneaus, a predator, and Aphidius rhopalosiphi de Stefani Perez, a parasitoid, on spread of barley yellow dwarf virus (BYDV) transmitted by the bird cherry–oat aphid, Rhopalosiphum padi (Linnaeus) were studied under laboratory conditions. Predators or parasitoids were introduced to trays of durum wheat seedlings and the patterns of virus infection were observed after two, seven and 14 days of exposure. More plants were infected with BYDV in control trays without A. rhopalosiphithan in trays with the parasitoid present, both seven and 14 days after the introduction of parasitoids. Patterns of virus infection were found to be similar over time in trays with a parasitoid present and in control trays. More plants were infected in trays with C. septempunctata present than in control trays, both two and seven days after the introduction of the coccinellid. The spread of virus infections progressed differently over time for the two treatments (predator and parasitoid), differences between treatments being most marked after two days and seven days, when more plants exposed to predators but fewer exposed to parasitoids were infected with BYDV compared to their respective controls. However, by the 14th day 88% of all plants were infected and there was no significant difference between the two treatments. The role of natural enemies in spread of BYDV is discussed.
Factors affecting parasitism by Microctonus aethiopoides (Hymenoptera: Braconidae) and parasitoid development in natural and novel host species
Authors: Barratt B.I.P. , Johnstone P.D.
Published: March 2011

A laboratory study of aspects of parasitoid host acceptance, suitability and physiological regulation in natural and novel host species was carried out to investigate the degree of variability encountered with different hosts and to determine the value of such observations in host range determination. The parasitoid Microctonus aethiopoides Loan was exposed to a natural host, Sitona discoideus Gyllenhal (Coleoptera: Curculionidae) and three novel hosts, the New Zealand native Nicaeana cervinaBroun, the introduced weed biological control agent Rhinocyllus conicus (Froehlich), and a congeneric pest species, Sitona lepidus Gyllenhal (all Coleoptera: Curculionidae). Per cent parasitism of these species was 54%, 43%, 39% and 0%, respectively. The results indicated that for both S. discoideus and R. conicus more males than females were parasitized (69% cf. 45%, and 49% cf. 32% respectively) but host size was not a significant factor. Overall, superparasitism was recorded in about 29% of parasitized weevils and there was evidence that host discrimination to avoid superparasitism occurred in the natural host. Conversely, superparasitism occurred more frequently than would be expected in N. cervina (42%) coupled with higher survival of larvae in superparasitized hosts in this species. The frequency distribution of attack of R. conicus by M. aethiopoides was not different from random. Parasitoid development was more rapid in the natural host, S. discoideus, and parasitoid size was positively correlated with host size. There was a strong positive relationship between parasitoid larval survival and the presence of teratocytes in all hosts. Host fecundity and fertility were reduced by parasitism for most species, and in some cases, by exposure to parasitoids in the absence of detectable parasitism. It was concluded that laboratory observations can provide useful information on the compatibility between host and parasitoid which can complement traditional host range tests to predict field host range.
Evaluation of diets for the development and reproduction ofFranklinothrips orizabensis(Thysanoptera: Aeolothripidae)
Authors: Hoddle M.S. , Jones J. , Oishi K. , Morgan D. , Robinson L.
Published: March 2011

The suitability of ten diets for the development and reproduction ofFranklinothrips orizabensisJohansen, the key natural enemy ofScirtothrips perseaeNakahara, a pest of California grown avocados, was determined in the laboratory. The experimental diets evaluated were: (i) irradiatedEphestia kuehniellaZeller eggs; (ii) irradiatedE. kuehniellaeggs and avocado pollen; (iii)Tetranychus pacificusMcGregor eggs; (iv)T. pacificuseggs and avocado pollen; (v) irradiatedE. kuehniellaeggs andT. pacificuseggs; (vi) irradiatedE. kuehniellaeggs,T. pacificuseggs and avocado pollen; (vii)Scirtothrips perseae; (viii)Heliothrips haemorrhoidalis(Bouchè); (ix) avocado pollen; and (x) a young avocado leaf.Franklinothrips orizabensislarvae were unable to develop to adulthood on diets 9 and 10. The remaining eight diets supported complete development ofF. orizabensis, but only diets 1, 2, 5, 6, 7 and 8 produced fecund females. On diet 5,F. orizabensisexhibited high larval to adult survivorship (90%), mated females exhibited highest daily and lifetime fecundity, and the progeny of mated females were female biased (53%). Analysis of jackknife estimates of net reproduction (Ro), intrinsic rate of increase (rm), and finite rate of increase (λ) were all significantly greater forF. orizabensisreared on irradiatedE. kuehniellaeggs andT. pacificuseggs (i.e. diet 5) than corresponding values for other diets on which femaleF. orizabensiswere able to complete development and reproduce. Incorporation of avocado pollen into diets had an adverse effect on demographic statistics forF. orizabensis, and low quality diets resulted in male biased sex ratios for this predator.
Differential behaviour of Anopheles gambiae sensu stricto (Diptera: Culicidae) to human and cow odours in the laboratory
Authors: Pates H.V. , Takken W. , Stuke K. , Curtis C.F.
Published: March 2011

A dual port olfactometer was used to study the response of Anopheles gambiaeGiles sensu stricto to odours of human and animal origin. Human odour consisted of human skin emanations collected on a nylon stocking, which was worn for 24 h. This was tested alone or together with 4.5% carbon dioxide, the concentration in human and cattle breath. Cattle odours consisted of cow skin emanations and/or carbon dioxide. Cow skin emanations were collected by tying a nylon stocking (‘cow sock’) around the hind leg of a cow for 12 h. Anopheles gambiae s.s. was consistently highly attracted by human odour, which is consistent with the high degree of anthropophily in this mosquito. Anopheles gambiae s.s. was not attracted by human or cattle equivalent volumes of carbon dioxide and this gas did not enhance the effect of human skin residues. Furthermore, A. gambiae s.s. showed a high degree of aversion to cow odour. When human odour and cow odour were tested together in the same port, mosquitoes were still highly attracted, indicating that whilst cattle odour may deter A. gambiae s.s., these mosquitoes can detect human odour in the presence of cattle odour. It was concluded that carbon dioxide plays a minor role in the host seeking behaviour of A. gambiae s.s., whilst host specific cues such as human skin residues play a major role and very effectively demonstrated anthropophilic behaviour in the laboratory.
Fasciola hepatica: surfaces involved in movement of miracidia and cercariae
Authors: Bennett C.E.
Published: March 2011

Rapid freezing and substitution with fixative prior to scanning electron microscopy was used to demonstrate the pattern of beat and recovery of the cilia of free swimming miracidia of Fasciola hepatica. There were stages of dexioplectic metachronal co-ordination and the power stroke was approximately 15° anticlockwise from the anterior–posterior axis. Around the circumference of the body of the miracidia there were approximately 12 metachronal waves of power and recovery. Free-swimming cercariae were recorded by time-lapse photography and, after conventional fixation, by scanning electron microscopy. Cercarial tail-beats were to the posterior of the body in the lateral plane at a rate of 8 Hz. The tail has paired lateral ridges positioned to act as leading edges. There is an array of 32 sensory papillae on the mid-ventral surface of the tail. The tegument of the most distal part of the tail is described: it is free of sensory endings and the surface shows a spiral pattern.
Influence of mouse strain, infective dose and larval burden in the brain on activity in Toxocara-infected mice
Authors: Cox D.M. , Holland C.V.
Published: March 2011

Outbred LACA mice and inbred NIH mice were administered low (100 ova), medium (1000 ova), high (3000 ova) and trickle (4×250 ova) doses of Toxocara canis ova and the effect of infection on activity was examined with respect to: (i) the dose of ova administered and (ii) the number of larvae recovered from the brain. Larval recovery from the brain was significantly reduced in NIH mice compared to LACA mice for the 1000, 3000 and trickle doses. Mice from each strain were divided into larval intensity groupings based upon the number of larvae recovered from their brain. Activity for each mouse was measured pre- and post-infection by observing its behaviour in the home cage. Activity was assessed by monitoring six different independent categories of murine behaviour – ambulation, grooming, rearing, digging, climbing and immobility. Within each behavioural category, the duration of time spent at each behaviour per mouse within one thousandth of a second, the number of short bouts performed and the number of long bouts of behaviour performed were recorded over a 20 min period. Activity of LACA and NIH mice differed prior to infection. LACA mice spent more time immobile compared to NIH mice, which ambulated and climbed more. Variations in activity were also observed between groups of mice prior to infection. The effect of infection differed by strain, by dose and by larval intensity. Post-infection LACA mice became more immobile and ambulated less. NIH mice showed reduced immobility, but while ambulation decreased digging and climbing increased post-infection. Short bouts of activity remained unchanged among LACA mice post-infection but showed an increase for some behaviours in NIH mice.
Echinococcus multilocularis in carnivores from the Klatovy district of the Czech Republic
Authors: Martínek K. , Kolárová L. , Cervený J.
Published: March 2011

A unique human case of alveolar echinococcosis was described in 1979 from the Klatovy district of the Czech Republic. However, there were no previous epidemiological studies in this area focusing on detection of the source of infection – Echinococcus multilocularis adults producing eggs. During the period June 1997 to April 1999, 29 out of a total of 46 (63.3%) red foxes (Vulpes vulpes) in the Klatovy district and one of four foxes (25.0%) in the Pilsen South district were found to be infected with adult worms of E. multilocularis. No E. multilocularis adults were found in other animals from the Klatovy district (i.e. three specimens of Martes martes, two Martes foina, one Mustela erminea, two Meles meles and one Felis catus f. domestica). An examination of faecal samples from 55 dogs (Canis familiaris) from the Klatovy district resulted in the detection of E. multilocularis DNA in one (1.8%) sample. The present results support the possibility that human alveolar echinococcosis previously described in the Czech Republic had the character of an autochthonous infection. There are also indications of a potential risk of infection to humans.
Ultrastructure of the tegument of Saccocoelioides godoyi
Authors: Cohen S.C. , Kohn A. , de Fatima Diniz Baptista-Farias M.
Published: March 2011

The tegument of adult Saccocoelioides godoyi Kohn & Froes, 1986 (Digenea: Haploporidae), specimens of which were collected from the intestine of the freshwater fish, Leporinus friderici (Bloch, 1794) (Anostomidae) from the reservoir of Itaipu Hydroelectric Power Station, Parana State, Brazil, was studied by transmission electron microscopy. The tegument comprises an external anucleate layer, covered by a surface plasma membrane and associated glycocalyx. The surface layer is bound by the basal plasma membrane and contains spines, two types of inclusion bodies and mitochondria. Tegumental cell bodies are located beneath the surface musculature and contain a single nucleus, cytoplasm with rough endoplasmic reticulum, mitochondria, ribosomes, and inclusion bodies similar to those found in the external layer. Cytoplasmic strands connect the cell bodies to the external surface layer, suggesting that the inclusion bodies are produced in these cells and pass up into the syncytium, as is known for other digeneans from experimental evidence.
Fasciola gigantica: surface topography of the adult tegument
Authors: Dangprasert T. , Khawsuk W. , Meepool A. , Wanichanon C. , Viyanant V. , Upatham E.S. , Wongratanacheevin S. , Sobhon P.
Published: March 2011

Adult Fasciola gigantica are leaf-shaped with tapered anterior and posterior ends and measure about 35 mm in length and 15 mm in width across the mid section. Under the scanning electron microscope its surface appears rough due to the presence of numerous spines and surface foldings. Both oral and ventral suckers have thick rims covered with transverse folds and appear spineless. On the anterior part of the ventral surface of the body, the spines are small and closely-spaced. Each spine has a serrated edge with 16 to 20 sharp points, and measures about 20 μm in width and 30 μm in height. In the mid-region the spines increase in size (up to 54 μm in width and 58 μm in height) and number, especially towards the lateral aspect of the body. Towards the posterior end the spines progressively decrease in both size and number. The tegumental surface between the spines appears highly corrugated with transverse folds alternating with grooves. At higher magnifications the surface of each fold is further increased with a meshwork of small ridges separated by variable-sized pits or slits. There are three types of sensory papillae on the surface. Types 1 and 2 are bulbous, measuring 4–6 μm in diameter at the base with nipple-like tips, and the type 2 also have short cilia. Type 3 papillae are also bulbous and of similar size but with a smooth surface. These sensory papillae usually occur in clusters, each having between 2 and 15 units depending on the region of the body. Clusters of papillae on the lateral aspect (usually types 1 and 2) and around the suckers (type 3) tend to be more numerous and larger in size. The dorsal side of the body exhibits similar surface features, but the spines and papillae appear less numerous and are smaller. Corrugation and invaginations of the surface are also less extensive than on the ventral side of the body.
Larval Lake Whitefish abundance, diet and growth and their zooplankton prey abundance during a period of ecosystem change on the Bay of Quinte, Lake Ontario
Authors: Hoyle James A. , Johannsson Ora E. , Bowen Kelly L.
Published: March 2011

Studies to examine larval Lake Whitefish (Coregonus clupeaformis) abundance, diet composition and growth, and the abundance of their zooplankton prey were conducted during eight years (1991–1993, 1995–1996 and 2003–2005) over the course of two decades that spanned a period of major ecosystem change—primarily dreissenid mussel related impacts—on the Bay of Quinte, northeastern Lake Ontario. Larval fish were captured in shallow, nearshore waters (0.2–2.0 m) from early April to mid-May each year. Larval Lake Whitefish fed primarily on cyclopoid copepods and small-bodied cladocerans. The key finding of our studies was that prey abundance declined by 89% from the earlier (1991–1993, 1995–1996) to the later (2003–2005) sampling years. Larval fish growth during spring was significantly correlated with prey availability. Recruitment to the juvenile stage in August was correlated with spring prey availability and larval fish growth. The observed decline in larval Lake Whitefish prey in the Bay of Quinte may be contributing to poor stock performance during and following a period of significant ecosystem change.
A comparison of approaches for integrated management in coastal marine areas of Canada with the historical approach used in the Great Lakes (Bay of Quinte)
Authors: Randall R. G. , Koops M. A. , Minns C. K.
Published: March 2011

Canadian approaches for ecosystem-based management in coastal marine areas, prompted by Canada's Oceans Act, are similar to and consistent with the long-standing, integrated management of the Bay of Quinte in Lake Ontario. The similarities include the criteria for the identification of ecologically significant areas and habitat, degraded areas, ecologically significant species, depleted or rare species, conservation objectives and ecological indicators to assess the status of ecosystem components. The rationale for integrated management in the Bay of Quinte is compared to marine areas, using the terminology that has been adopted for ocean area-based management in Canada. The three overarching goals of maintaining productivity, preserving biodiversity and protecting habitat are common to both freshwater and marine ecosystems. Communication of science priorities is mutually beneficial for advancing integrated management in both ecosystem types. Identifying the Bay of Quinte as a coastal management area by Great Lakes agencies, using elements of the oceans framework, would demonstrate a transition from a negative (degraded area) to a positive ecosystem status (essential habitat with high productivity and biodiversity).
The relative importance of autotrophic and heterotrophic microbial communities in the planktonic food web of the Bay of Quinte, Lake Ontario 2000–2007
Authors: Munawar M. , Fitzpatrick M. , Niblock H. , Lorimer J.
Published: March 2011

The structure and function of the microbial and planktonic communities of the Bay of Quinte, Lake Ontario were studied for 8 years from 2000 to 2007. The bay has a long history of eutrophication and has undergone remediation efforts which included reductions in phosphorus loadings and the implementation of a long term research and monitoring program (1972–present) conducted by Fisheries and Oceans Canada along with other federal and provincial agencies. Microbial loop research was added in 2000 to the ongoing monitoring program which included nutrients, phytoplankton, zooplankton, benthos and fish so that a comprehensive picture of food web linkages would emerge. The structure of the microbial-planktonic food web was determined based on microscopic analysis of bacteria, autotrophic picoplankton (APP), heterotrophic nanoflagellates (HNF), ciliates, phytoplankton and zooplankton and was compared to a traditional grazing food chain consisting of phytoplankton and zooplankton. On a seasonal weighted mean basis, HNF biomass (fresh weight) of 1.7–8.4 g m−3 at Belleville and 1.1–6.3 C m−3 at Conway exceeded that of zooplankton in virtually all observations and was often greater than the combination of phytoplankton and zooplankton. Furthermore, the results showed that HNF contributed upwards to 85% of the organic carbon pool on a seasonal weighted mean basis. Various parameters in the upper bay relating trophic status to autotrophic communities were measured including: point source phosphorus loadings (>10 kg d−1); primary production (>300 g C m−2 y−1); chlorophyll a (>12 μg l−1) and phytoplankton biomass (>3 g m−3) which indicated that the upper bay remained eutrophic. This was also confirmed by the “battery of tests” strategy of ecological indicators developed in our laboratory to assess trophic status, health, and potential Beneficial Use Impairments. Based on our observations spanning 8 years, it was concluded that the microbial food web was dominated by heterotrophic communities which are still widely ignored in Great Lakes research and monitoring efforts. Our data clearly demonstrates that future studies and management strategies should include the “microbial loop” to obtain a holistic picture of the structure, function and dynamics of the lower food web.
Vacuum UV broad-band absorption spectroscopy: a powerful diagnostic tool for reactive plasma monitoring
Authors: Cunge G , Fouchier M , Brihoum M , Bodart P , Touzeau M , Sadeghi N
Published: March 2011

Broad band UV–visible absorption spectroscopy is widely used to measure the concentration of radicals in reactive plasmas. We extended the applicability of this technique to the VUV (115 nm to 200 nm), the spectral range in which the electronic transitions from the ground state to the Rydberg or pre-dissociated states of many closed-shell molecules are located. This gives access to the absolute densities of species which do not, or weakly absorb in the UV–visible range. The technique is demonstrated by measuring the densities of HBr and Br2 molecules in HBr high-density ICP plasmas.
Highly controllable near-surface swimming of magnetic Janus nanorods: application to payload capture and manipulation
Authors: Mair Lamar O , Evans Emily , Hall Adam R , Carpenter Jerome , Shields Adam , Ford Kris , Millard Michael , Superfine Richard
Published: March 2011

Directed manipulation of nanomaterials has significant implications in the field of nanorobotics, nanobiotechnology, microfluidics and directed assembly. With the goal of highly controllable nanomaterial manipulation in mind, we present a technique for the near-surface manoeuvering of magnetic nanorod swimmers and its application to controlled micromanipulation. We fabricate magnetic Janus nanorods and show that the magnetic rotation of these nanorods near a floor results in predictable translational motion. The nanorod plane of rotation is nearly parallel to the floor, the angle between rod tilt and floor being expressed by θ, where 0° < θ < 20°. Orthogonal magnetic fields control in-plane motion arbitrarily. Our model for translation incorporates symmetry breaking through increased drag at the no-slip surface boundary. Using this method we demonstrate considerable rod steerability. Additionally, we approach, capture, and manipulate a polystyrene microbead as proof of principle. We attach Janus nanorods to the surfaces of cells and utilize these rods to manipulate individual cells, proving the ability to manoeuver payloads with a wide range of sizes.
Analytical modelling of drain-current characteristics of AlGaN/GaN HFETs with full incorporation of steady-state velocity overshoot
Authors: Loghmany Alireza , Valizadeh Pouya
Published: March 2011

An analytical model for drain-current characteristics of AlGaN/GaN heterostructure field-effect transistors (HFETs), with incorporation of steady-state velocity overshoot and the inflection points in the electronic drift-transport characteristics, is presented. Manifestations of these transport characteristics are usually neglected in modelling the drain current of III–V HFETs. However, significance of these features in AlGaN/GaN material system, compared with other III–V technologies, requires re-evaluation of this policy. Although, for the current state of the art these features are partially masked by the parasitic features such as the drain and source contact resistance, through further improvement in the device fabrication technology they will deserve further attention. The wide peak and pronounced inflection points in the transport characteristics of AlGaN/GaN heterojunctions are modelled through considering a drift-diffusion channel rather than a drift-only transport channel. Simulation results are compared with a non-diffusion type channel that has been so far assumed in modelling the drain current of these devices. Results of the presented model indicate the role of drift-velocity overshoot in further increasing the maximum drain current of AlGaN/GaN HFETs, as the contact resistance is reduced. Comparisons with the experimental measurements are also provided.
Gallium and indium co-doping of epitaxial zinc oxide thin films grown in water at 90 °C
Authors: Le Hong Quang , Chua Soo Jin
Published: March 2011

Zinc oxide (ZnO) thin films were intentionally co-doped with group III elements (gallium) in order to investigate and understand the effects of co-doping on the morphological, electrical and optical properties of gallium-doped ZnO (GZO) films. The co-doped films were grown on MgAl2O4 spinel substrates using a low-temperature solution-phase method known as hydrothermal synthesis. Gallium with indium co-doped ZnO (GIZO) films displayed a dramatic improvement in surface morphology as compared with the Ga-doped ZnO (GZO) films due to the compensation effect of gallium and indium doping which reduced the lattice strain. The 0.0033M gallium with 3.3 × 10−4M indium co-doped film exhibited an electron concentration of 3.14 × 1020 cm−3 and resistivity of 7.4 × 10−4 Ω cm which were both enhancements of 1.5 times over the GZO film. These films were comparable to the films fabricated by more expensive and complicated vapour-phase methods. The figure of merit for this film was determined to be 1.63 × 10−2 sq/Ω which was very close to the indium tin oxide conducting films currently used commercially. Finally, the GIZO film was hydrothermally grown on a p-GaN film to form an n-ZnO/p-GaN heterojunction light-emitting diode (LED). This LED showed diode I–V characteristics and exhibited strong cool-white light emission which signified the prospect of using GIZO as an effective and low-cost n-type layer in LEDs.
Coexistence of the bipolar and unipolar resistive switching behaviours in Au/SrTiO3/Pt cells
Authors: Sun Xianwen , Li Guoqiang , Zhang Xin'an , Ding Linghong , Zhang Weifeng
Published: March 2011

The bipolar and unipolar resistive switching (BRS and URS) modes are first observed to coexist in the Au/SrTiO3/Pt cell fabricated by pulsed laser deposition. These two switching modes can be activated separately depending on the different current compliance (CC) during the electroforming process: with a lower CC (1 mA) the asymmetric BRS behaviour is measured in the voltage range −1.2 to +1 V, while the URS behaviour is observed with a higher CC (10 mA). On the basis of current–voltage characteristics, the switching mechanisms for the BRS and URS modes are considered as a change in Schottky-like barrier height and/or width at the Au/SrTiO3 interface and the formation and disruption of conduction filaments, respectively. The conversion between BRS and URS is reversible. Because each switching mode has a specific advantage, selecting the desired switching mode can broaden the application scope of the cell and enable large flexibility in terms of memory architecture.
Comparison of the reflection properties of a metal wire in the visible spectral and terahertz regime
Authors: He Xiaoyong , Zhong Xu
Published: March 2011

The corresponding author, Xiaoyong He is affiliated to only one address. This is:

School of Science, Henan University of Technology, Lianhua Road, Zhengzhou, Henan Province, 450001, People's Republic of China.
Improvement of the signal-to-noise ratio of laser-induced-fluorescence photon-counting signals of single-atoms magneto-optical trap
Authors: He Jun , Yang Baodong , Zhang Tiancai , Wang Junmin
Published: March 2011

Employing grating extended-cavity diode lasers as the cooling/trapping and repumping lasers for preparing and manipulating single atoms, we have implemented a large-magnetic-gradient caesium magneto-optical trap (MOT). To detect and evaluate single caesium atoms trapped in MOT, laser-induced-fluorescence (LIF) photons of trapped atoms driven by MOT lasers are collected and counted by an avalanched photodiode worked in photon-counting mode. The dependences of LIF photon-counting signals of single atoms on a cooling laser's intensity, frequency detuning and frequency fluctuation are analysed and investigated. Remarkable improvement of the signal-to-noise ratio of LIF photon-counting signals is achieved by optimizing the cooling laser's intensity and frequency detuning and using the modulation-free polarization spectroscopic technique with feedback to both the slow channel (piezoelectric transducer channel with typical bandwidth of ∼2 kHz in the grating extended cavity) and the fast channel (current modulation channel with typical bandwidth of ∼200 kHz in the current driver).
Influence of a bias voltage on surface-driven orientational transitions for liquid crystal-based chemical and biological sensors
Authors: Zou Yang , Namkung Jun , Lin Yongbin , Ke Dan , Lindquist Robert G
Published: March 2011

The influence of a bias voltage on the surface-driven orientational transitions of liquid crystals (LCs) resulting from the weakening anchoring and anchoring transition was analysed theoretically and experimentally. The continuum theory of nematic LCs was used to model the LC deformation under different anchoring energies. A microelectroplated interdigitated Au structure was used in the nematic LC-based chemical and biological sensors. With a suitable bias electric field, the processes of the weakening anchoring energy and the uniform surface-driven orientational transition due to targeted molecules binding to a functionalized surface were observed optically. These results can be used to improve the sensitivity, response speed and signal strength of LC-based chemical and biological sensors.
High-fluence femtosecond laser ablation of silica glass: effects of laser-induced pressure
Authors: Hu Haofeng , Wang Xiaolei , Zhai Hongchen
Published: March 2011

A pump-probe technique is employed to investigate the dynamic process of femtosecond laser ablation of silica glass, and three stress waves are observed inside the silica glass in the time-resolved shadowgraphs at a fluence of 40 J cm−2. It is believed that the first stress wave is a thermoelastic wave generated by thermal expansion, while the second and the third are generated subsequently by the mechanical expansions as a result of the extremely high pressure induced by the laser. By employing digital holography, the ablation crater is investigated to identify the ablation results, and high-density silica glass is found beneath the ablation crater, which is also the result of the laser-induced pressure. Furthermore, it is found that more stress waves will be generated at a higher fluence, and the thresholds for the generation of the first, second and third stress wave are measured to be about 2 J cm−2, 6 J cm−2 and 31 J cm−2, respectively. The theoretical calculation result shows that the laser-induced pressure increases with the increase in fluence and can be on the scale of TPa, and we believe a higher pressure will induce more mechanical expansions and therefore more stress waves.
Statistical time lags in ac discharges
Authors: Sobota A , Kanters J H M , van Veldhuizen E M , Manders F , Haverlag M
Published: March 2011

The paper presents statistical time lags measured for breakdown events in near-atmospheric pressure argon and xenon. Ac voltage at 100, 400 and 800 kHz was used to drive the breakdown processes, and the voltage amplitude slope was varied between 10 and 1280 V ms−1. The values obtained for the statistical time lags are roughly between 1 and 150 ms. It is shown that the statistical time lags in ac-driven discharges follow the same general trends as the discharges driven by voltage of monotonic slope. In addition, the validity of the Cobine–Easton expression is tested at an alternating voltage form.
Charged particle dynamics in a ‘high-pressure’ laser ion source
Authors: Yeates P , Costello J T , Kennedy E T
Published: March 2011

Charged particle sources require beam transport techniques specific to the application for optimum operation. The complexity of techniques increases as the degree of ionization and kinetic energy of charged particles increases. The Dublin City University laser ion source (DCU-LIS) utilizes a short field region (L = 48 mm) to maximize the average charge state and peak current extracted, thus ion extraction occurs at ‘high pressure’. The presence of large space-charge forces, high average plasma plume temperature and the expansion dynamics of laser-generated plasmas results in significant divergence of the ion bunch upon injection into the drift tube. To facilitate efficient beam transport, and to maximize system throughput, we employ a rather unique electrostatic transport system, termed as ‘continuous einzel array’ (CEA). Ion electrodynamics in such a system exhibit a number of distinct features which modify the system performance and alter the expected distribution of kinetic energies (K

E
), the times of flight and ion bunch diameters. System scalability in regard to beam kinetic energy is also important. In this paper the superior performance of the LIS equipped with a CEA is compared with a traditional einzel lens electrostatic beam transport system based on the usual 3-element and also a 5-element lens system.
Chemical ordering phase transitions in Ni–Fe nanoalloys
Authors: Li P Y , Lu H M , Jiang Z H , Huang Y N , Meng X K
Published: March 2011

The chemical ordering phase transitions in Ni75Fe25 and Ni70Fe30 nanoalloys are investigated by differential scanning calorimetry (DSC), mechanical spectroscopy (MS), vibrating sample magnetometer (VSM) measurements and thermodynamical calculation. An internal friction peak occurs at 646 K in the Ni75Fe25 nanoalloy with an average grain size of 23 nm diameter during MS measurement. An exothermic peak appears during the DSC tests of nanoalloys. Associated with the results of thermodynamical prediction and VSM measurements, both the exothermic peak and the internal friction peak are convinced to be originated from chemical ordering phase transition. Compared with inefficacy of electron diffraction and x-ray diffraction, it is an effective route of employing DSC, MS, VSM and thermodynamical prediction in investigating the chemical ordering phase transitions in Ni–Fe nanoalloys.
Study of melt flow dynamics and influence on quality for CO2 laser fusion cutting
Authors: Riveiro A , Quintero F , Lusquiños F , Comesaña R , Pou J
Published: March 2011

The understanding of melt flow dynamics during fusion laser cutting is still a topic of great importance because this determines the quality characteristics of the processed workpiece. Despite the complexity of the experimental study of the physical processes involved in this technique, fusion laser cutting can be visualized during the processing of glass because this material absorbs the laser radiation provided by a CO2 laser but shows transparency to visible radiation. Then, we present in this work the results of the study of the melt flow dynamics during laser cutting of glass. Under different experimental conditions, the dynamics of the cutting front and its complete geometry (front wall inclination), and the evolution of the melt along the cut edge were analysed using a high-speed video camera to study the process. A phenomenon concerning the plasma plume formed during the process was observed, which has not been previously reported in the literature. This can displace the normal shock wave (MSD) commonly formed in the inlet kerf and can affect the assist gas flow into the kerf.

On the other hand, the analysis of the recorded images allowed the determination of not only the amount of molten material along the cut edge but also the direction and velocity of the melt. Relevant processing parameters affecting the flow of molten material were assessed. These results were used as a basis to explain the different processes involved in the generation of dross, a typical imperfection appearing in laser cutting.
The biomechanics of fast prey capture in aquatic bladderworts
Authors: Singh Amit K. , Prabhakar Sunil , Sane Sanjay P.
Published: March 2011

Carnivorous plants match their animal prey for speed of movements and hence offer fascinating insights into the evolution of fast movements in plants. Here, we describe the mechanics of prey capture in aquatic bladderwortsUtricularia stellaris, which prey on swimming insect larvae or nematodes to supplement their nitrogen intake. The closedUtriculariabladder develops lower-than-ambient internal pressures by pumping out water from the bladder and thus setting up an elastic instability in bladder walls. When the external sensory trigger hairs on their trapdoor are mechanically stimulated by moving prey, the trapdoor opens within 300–700μs, causing strong inward flows that trap their prey. The opening time of the bladder trapdoor is faster than any recorded motion in carnivorous plants. Thus,Utriculariahave evolved a unique biomechanical system to gain an advantage over their animal prey.
Shoreline urbanization interrupts allochthonous subsidies to a benthic consumer over a gradient of lake size
Authors: Larson Eric R. , Olden Julian D. , Usio Nisikawa
Published: March 2011

The role of resource subsidies across ecosystem boundaries has emerged as an important concept in contemporary ecology. For lake ecosystems, this has led to interest in quantifying the contribution of terrestrial allochthonous carbon to aquatic secondary production. An inverse relationship between habitat area and the role of allochthonous subsidies has been documented on marine islands and assumed for lakes, yet there have been no tests of this pattern among benthic (lake bottom) consumers. Here, we used carbon stable isotopes to trace terrestrial allochthonous and benthic autochthonous carbon use by the crayfishPacifastacus leniusculusover a gradient of lake area, productivity and urbanization. Consistent with findings from terrestrial islands, habitat size dictated the importance of allochthonous subsidies, asP. leniusculustransitioned from using predominantly terrestrial carbon in small lakes to an increased reliance on autochthonous production in larger lakes. However, shoreline urbanization interacted with this pattern, particularly for small lakes where greater urbanization resulted in reduced use of allochthonous resources. As such, we provide, to our knowledge, the first confirmation of the predicted relationship between habitat size and importance of allochthonous subsidies to lake benthic consumers, but found that urbanization can interfere with this pattern.
Random search with
k
-prototypes algorithm for clustering mixed datasets
Authors: Pham Duc-Truong , Suarez-Alvarez Maria M. , Prostov Yuriy I.
Published: March 2011

A new algorithm to cluster datasets with mixed numerical and categorical values is presented. The algorithm, called RANKPRO (random search with
k
-prototypes algorithm), combines the advantages of a recently introduced population-based optimization algorithm called the bees algorithm (BA) and
k
-prototypes algorithm. The BA works with elite and good solutions, and continues to look for other possible extrema solutions keeping the number of testing points constant. However, the improvement of promising solutions by the BA may be time-consuming because it is based on random neighbourhood search. On the other hand, an application of the
k
-prototypes algorithm to a promising solution may be very effective because it improves the solution at each iteration. The RANKPRO algorithm balances two objectives: it explores the search space effectively owing to random selection of new solutions, and improves promising solutions fast owing to employment of the
k
-prototypes algorithm. The efficiency of the new algorithm is demonstrated by clustering several datasets. It is shown that in the majority of the considered datasets when the average number of iterations that the
k
-prototypes algorithm needs to converge is over 10, the RANKPRO algorithm is more efficient than the
k
-prototypes algorithm.
Quantification of fibre polymerization through Fourier space image analysis
Authors: Nekouzadeh Ali , Genin Guy M.
Published: March 2011

Quantification of changes in the total length of randomly oriented and possibly curved lines appearing in an image is a necessity in a wide variety of biological applications. Here, we present an automated approach based upon Fourier space analysis. Scaled, band-pass filtered power spectral densities of greyscale images are integrated to provide a quantitative measurement of the total length of lines of a particular range of thicknesses appearing in an image. A procedure is presented to correct for changes in image intensity. The method is most accurate for two-dimensional processes with fibres that do not occlude one another.
Fight tactics in wood ants: individuals in smaller groups fight harder but die faster
Authors: Batchelor Tim P. , Briffa Mark
Published: March 2011

When social animals engage in inter-group contests, the outcome is determined by group sizes and individual masses, which together determine group resource-holding potential (‘group RHP’). Individuals that perceive themselves as being in a group with high RHP may receive a motivational increase and increase their aggression levels. Alternatively, individuals in lower RHP groups may increase their aggression levels in an attempt to overcome the RHP deficit. We investigate how ‘group RHP’ influences agonistic tactics in red wood antsFormica rufa. Larger groups had higher total agonistic indices, butper capitaagonistic indices were highest in the smallest groups, indicating that individuals in smaller groups fought harder. Agonistic indices were influenced by relative mean mass, focal group size, opponent group size and opponent group agonistic index. Focal group attrition rates decreased as focal group relative agonistic indices increased and there was a strong negative influence of relative mean mass. The highest focal attrition rates were received when opponent groups were numerically large and composed of large individuals. Thus, fight tactics inF. rufaseem to vary with both aspects of group RHP, group size and the individual attributes of group members, indicating that information on these are available to fighting ants.
Effect of pyruvate on the metabolic regulation of nitrogenase activity in Rhodospirillum rubrum in darkness
Authors: Selao Tiago Toscano , Edgren Tomas , Wang He , Norén Agneta , Nordlund Stefan
Published: March 2011

Rhodospirillum rubrum, a photosynthetic diazotroph, is able to regulate nitrogenase activity in response to environmental factors such as ammonium ions or darkness, the so-called switch-off effect. This is due to reversible modification of the Fe-protein, one of the two components of nitrogenase. The signal transduction pathway(s) in this regulatory mechanism is not fully understood, especially not in response to darkness. We have previously shown that the switch-off response and metabolic state differ between cells grown with dinitrogen or glutamate as the nitrogen source, although both represent poor nitrogen sources. In this study we show that pyruvate affects the response to darkness in cultures grown with glutamate as nitrogen source, leading to a response similar to that in cultures grown with dinitrogen. The effects are related to PIIprotein uridylylation and glutamine synthetase activity. We also show that pyruvate inducesde novoprotein synthesis and that inhibition of pyruvate formate-lyase leads to loss of nitrogenase activity in the dark.