bluuebunny/crossref_metadata_2025 huggingface dataset:
Size-dependent charge-separation reaction for hydrated sulfate dianion cluster, SO42−(H2O)n, with n=3–7
Authors: Gao Bing , Liu Zhi-feng
Published: December 2005

The decrease in the reaction rate for the charge separation in SO42−(H2O)n with increasing cluster size is examined by first-principles calculations of the energetics, activation barriers, and thermal stability for n=3–7. The key factor governing the charge separation is the difference in the strength of solvation interaction: while interaction with water is strong for the reactant SO42− and the product OH−, it is relatively weak for HSO4−. It gives rise to a barrier for charge separation as SO42− is transformed into HSO4− and OH−, although the overall reaction energy is exothermic. The barrier is high when more than two H2O are left to solvate HSO4−, as in the case of symmetric solvation structure and in the case of large clusters. The entropy is another important factor since the potential surface is floppy and the thermal motion facilitates the symmetric distribution of H2O around SO42−, which leads to the gradual reduction in reaction rate and the eventual switch-off of charge separation as cluster size increases. The experimentally observed products for n=3–5 are explained by the thermally most favorable isomer at each size, obtained by ab initio molecular-dynamics simulations rather than by the isomer with the lowest energy.
Theory of glassy dynamics in conformationally anisotropic polymer systems
Authors: Oyerokun Folusho T. , Schweizer Kenneth S.
Published: December 2005

A mode coupling theory for the ideal glass transition temperature, or crossover temperature to highly activated dynamics in the deeply supercooled regime, Tc, has been developed for anisotropic polymer liquids. A generalization of a simplified mode coupling approach at the coarse-grained segment level is employed which utilizes structural and thermodynamic information from the anisotropic polymer reference interaction site model theory. Conformational alignment or/and coil deformation modifies equilibrium properties and constraining interchain forces thereby inducing anisotropic segmental dynamics. For liquid-crystalline polymers a small suppression of Tc with increasing nematic or discotic orientational order is predicted. The underlying mechanism is reduction of the degree of coil interpenetration and intermolecular repulsive contacts due to segmental alignment. For rubber networks chain deformation results in an enhanced bulk modulus and a modest elevation of Tc is predicted. The theory can also be qualitatively applied to systems that undergo nonuniversal local deformation and alignment, such as polymer thin films and grafted brush layers, and large elevations or depressions of Tc are possible. Extension to treat directionally dependent collective barrier formation and activated hopping is possible.
Observation of L uncoupling in the 5Δg1 Rydberg state of Na2
Authors: Chang Ray-Yuan , Tsai Chin-Chun , Whang Thou-Jen , Cheng Chuen-Ping
Published: December 2005

The phenomenon of electronic orbital angular momentum L uncoupled from its internuclear axis has been observed in the sodium dimer using high-resolution cw optical-optical double-resonance spectroscopy. When L uncoupling occurs, the degeneracy of Λ doubling is removed. In our experiment, the intermediate BΠu1 state of Na2 is excited from the thermally populated ground XΣg+1 state by a single-line Ar+ laser. Then, a single-mode dye laser is used to probe the Rydberg states from the intermediate state. The signals are detected by monitoring the UV fluorescence from the triplet gerade states back to the aΣu+3 state via collision energy transfer. Under our experimental resolution, the splitting of Λ doubling in the 5Δg1 state of Na2 can be measured. A total of 136 rovibronic levels with e∕f parities have been assigned to the 5Δg1 state. The Λ-splitting constants deduced from these data are q0=0.376(90)×10−4cm−1, qv=0.114(6)×10−4cm−1, and μ=0.76(33)×10−8cm−1. In general, the Λ splitting of the Δ states is considerably smaller than that of the Π states. However, the first-order splitting constants q0 and qv reported here are larger than those in the BΠu1 state. This is due to the L uncoupling of the Rydberg states.
Noncommutative unification of general relativity and quantum mechanics
Authors: Heller Michael , Pysiak Leszek , Sasin Wiesław
Published: December 2005

We present a model unifying general relativity and quantum mechanics based on a noncommutative geometry. This geometry is developed in terms of a noncommutative algebra A which is defined on a transformation groupoid Γ given by the action of a noncompact group G on the total space E of a principal fiber bundle over space-time M. The case is important since to obtain physical effects predicted by the model we should assume that G is a Lorentz group or some of its representations. We show that the generalized Einstein equation of the model has the form of the eigenvalue equation for the generalized Ricci operator, and all relevant operators in the quantum sector of the model are random operators; we study their dynamics. We also show that the model correctly reproduces general relativity and the usual quantum mechanics. It is interesting that the latter is recovered by performing the measurement of any observable. In the act of such a measurement the model “collapses” to the usual quantum mechanics.
Interface trap and oxide charge generation under negative bias temperature instability of p-channel metal-oxide-semiconductor field-effect transistors with ultrathin plasma-nitrided SiON gate dielectrics
Authors: Zhu Shiyang , Nakajima Anri , Ohashi Takuo , Miyake Hideharu
Published: December 2005

The interface trap generation (ΔNit) and fixed oxide charge buildup (ΔNot) under negative bias temperature instability (NBTI) of p-channel metal-oxide-semiconductor field-effect transistors (pMOSFETs) with ultrathin (2 nm) plasma-nitrided SiON gate dielectrics were studied using a modified direct-current–current-voltage method and a conventional subthreshold characteristic measurement. Different stress time dependences were shown for ΔNit and ΔNot. At the earlier stress times, ΔNit dominates the threshold voltage shift (ΔVth) and ΔNot is negligible. With increasing stress time, the rate of increase of ΔNit decreases continuously, showing a saturating trend for longer stress times, while ΔNot still has a power-law dependence on stress time so that the relative contribution of ΔNot increases. The thermal activation energy of ΔNit and the NBTI lifetime of pMOSFETs, compared at a given stress voltage, are independent of the peak nitrogen concentration of the SiON film. This indicates that plasma nitridation is a more reliable method for incorporating nitrogen in the gate oxide.
Photoacoustic Fourier transform infrared spectroscopy of nanoporous SiOx∕Si thin films with varying porosities
Authors: Yang D.-Q. , Meunier M. , Sacher E.
Published: December 2005

Nanostructured SiOx∕Si thin films, over a large range of porosities, were deposited by the excimer laser ablation (KrF, 248nm) of Si targets in He; they have been characterized by photoacoustic Fourier transform infrared spectroscopy, which necessitates exposure to air with subsequent oxidation. In particular, the IR Si–O–Si asymmetric stretching region, from 1000 to 1300cm−1, has been found to be composed of four components: P1 at 1045cm−1, P2 at 1060cm−1, P3 at 1090cm−1, and P4 at 1170cm−1. The photoacoustic signals were enhanced with increasing film porosity, as previously found for larger scale porous materials; those for P2–4 also correlated with similar increases in the O–H and C–Hn surface contaminant stretching peaks, indicating their sources to be in the surface region. We demonstrate that the experimental data fully support a previously proposed theoretical relationship, originally developed for powders.
Hysteresis in organic field-effect devices: Simulated effects due to trap recharging
Authors: Lindner Th. , Paasch G. , Scheinert S.
Published: December 2005

Current organic field-effect transistors feature predominantly undesirable hysteresis effects which appear also in the capacitance-voltage (CV) characteristics of organic metal-oxide-semiconductor (MOS) capacitors. So far, these effects are not sufficiently characterized experimentally and their origin is even less understood. In the literature one finds presumptions that they are caused by trap recharging or by mobile ions (in the organic semiconductor or in the insulator). In order to check the first of these presumptions, detailed numerical simulations have been carried out. Hysteresis in the field effect is studied at best in the MOS capacitor without the additional influence of the source/drain contacts of the transistor. Although there are differences between quasistatic and dynamic measurements, our simulations are done for the quasistatic CV characteristics since they already give the desired information for the understanding of the hysteresis effects. Organic semiconductors with different types of traps of different energetic positions, concentrations, and energetic and spatial distributions are considered and their parameters are varied in a wide range. Trap recharging is connected with the transport of the emitted (captured) carriers from (to) the traps during the voltage sweep. It is demonstrated that rather different types of hysteresis can occur thereby. All of the simulated shapes of the hysteresis are qualitatively different from that one which is typically observed experimentally. Therefore, it should be ruled out that the hysteresis observed in organic MOS devices is solely caused by trap recharging. The observed changes of the CV characteristics for a variation of different measuring conditions and parameters indicate that the hysteresis is caused by at least two different processes. We suppose that the origin of the hysteresis in organic devices is a combination of slow transport (polarons or mobile ions) with a reaction other than trap recharging, e.g., the direct polaron-bipolaron reaction or a complex formation reaction of polarons/bipolarons with counterions.
Origin of the front-back-gate coupling in partially depleted and fully depleted silicon-on-insulator metal-oxide-semiconductor field-effect transistors with accumulated back gate
Authors: Lukyanchikova N. , Garbar N. , Smolanka A. , Lokshin M. , Simoen E. , Claeys C.
Published: December 2005

It is shown that in thin-gate partially depleted silicon-on-insulator metal-oxide-semiconductor field-effect transistors (PD SOI MOSFETs) unexpected front-back-gate coupling effects occur when the back gate is operated in accumulation. This is particularly true for front-gate biases (VGF) beyond the threshold for electron valence-band tunneling to occur, inducing the so-called linear kink effect (LKE). As a consequence of this coupling, both the drain current and the drain-current noise spectral density are reduced in the LKE regime. Moreover, for a back-gate bias into stronger accumulation, the LKE regime is shifted to higher VGF in absolute value. Another consequence of the front-back-gate coupling is the appearance of the back-gate-induced (BGI) Lorentzian component in the noise spectra measured for an accumulated back gate in a wide range of VGF. Similar effects have also been detected in thin-gate fully depleted SOI MOSFETs. It is demonstrated that all these front-back coupling effects can be explained by considering the increased body-source leakage currents and, hence, the body-source conductance induced by the accumulation back-gate voltage where the BGI Lorentzian is attributed to the Nyquist noise in the back-gate-induced body-source conductance affected by the capacitive character of the body-source impedance.
Ab initio calculation of electron effective masses in solid pentacene
Authors: Doi K. , Yoshida K. , Nakano H. , Tachibana A. , Tanabe T. , Kojima Y. , Okazaki K.
Published: December 2005

We have calculated the band structures of solid pentacene. One of our models makes use of experimental data obtained for a single crystal [R. B. Campbell et al., Acta. Crystallogr. 14, 705 (1961); R. B. Campbell and J. M. Robertson, Acta. Crystallogr. 15, 289 (1962)] and the other one considers a thin film fabricated by the present authors. Our calculations indicate that the electronic properties of a pentacene thin film are markedly different from those of a single crystal, although the densities of pentacene molecules in these solids are not significantly different. The energy band gaps of the single crystal and the thin film have been estimated to be 0.73eV and between 0.26 and 0.72eV, respectively. The bandwidths of the highest valence band and the lowest conduction band of the film are wider than those of the single crystal. These results suggest that the electron or hole carriers in the film have effective masses lighter than those of the single crystal, and in order to estimate the carrier mobility we first calculate the effective mass.
Experiment on the dynamics of a compound drop impinging on a hot surface
Authors: Chiu Sheng-Lin , Lin Ta-Hui
Published: December 2005

A stable stream of compound drops which are composed of core fluid, water, encased by a layer of shell fluid, diesel, was utilized to investigate the dynamic behavior of a liquid-liquid compound drop impinging on a hot surface above the Leidenfrost temperature. The core-to-shell mass ratio and the modified normal Weber number, which takes into account the two interfaces involved, were taken to be the controlling parameters. The outcomes of a compound drop impacting on a hot surface consist largely of reflection with or without secondary drops. Based on energy conservation, the dissipated energy was estimated and a criterion for secondary drop formation was presented. The normal velocity after impact is reduced due to viscous dissipation while the tangential component remains almost unaffected. In addition, there is an interesting phenomenon of the core drop escaping from the compound drop. The experimental results show that an increasing core-to-shell mass ratio raises the momentum loss, reduces the number of secondary drops, and promotes core-drop escaping.
Scaling of the piezoelectric response in ferroelectric nanostructures: An effective clamping stress model
Authors: Nagarajan V.
Published: December 2005

It is well understood that due to substrate induced clamping the piezoresponse in thin ferroelectric films is lower than bulk. Recent studies on the effect of lateral scaling have shown that by creating nanostructures one can achieve high piezoelectric constants even in thin films. In this letter we present a simple analytical model, to describe the evolution of the out-of-plane piezoresponse as a function of the device size in 100-nm-thick PbZrxTi1−xO3 thin films. It is shown that by an effective clamping stress analysis, one can successfully map out the size dependence of the piezoelectric constants in thin ferroelectric films. The results of the model are also compared to the predictions made by finite element analysis.
Step-induced uniaxial magnetic anisotropy of La:67Sr:33MnO3 thin films
Authors: Mathews Mercy , Postma Ferry M. , Lodder J. Cock , Jansen R. , Rijnders Guus , Blank Dave H. A.
Published: December 2005

The magnetic anisotropy of epitaxial La0.67Sr0.33MnO3 (LSMO) thin films on vicinal, TiO2-terminated SrTiO3 substrates is investigated. Atomic force microscopy shows a regular step-terrace structure on the LSMO surface which is a replication of the surface of the substrate. The films show in-plane uniaxial magnetic anisotropy at room temperature, with the easy axis along the step direction. At low temperature the films show biaxial crystalline anisotropy with easy axes along [110], and hard axes along the [100] direction of LSMO.
Improved stoichiometry and misfit control in perovskite thin film formation at a critical fluence by pulsed laser deposition
Authors: Ohnishi T. , Lippmaa M. , Yamamoto T. , Meguro S. , Koinuma H.
Published: December 2005

Pulsed laser deposition (PLD) is a good method for growing high-quality functional oxide thin films because of the technical simplicity and the ease with which deposition can be switched from one material to another. However, the repeatability of film quality is often hard to achieve, especially when using several different PLD systems. Here we report the steps that we have taken to grow nearly bulk-equivalent defect-free thin films, with SrTiO3 as an example, by using PLD in a reproducible fashion. The ablation laser fluence was found to have a very strong effect on the lattice constant and defect structure of the films. Nonstoichiometric transfer of material from the ablation target was observed when either the laser fluence or the beam spot area was inadequate.
Enhanced higher-harmonic imaging in tapping-mode atomic force microscopy
Authors: Balantekin M. , Atalar A.
Published: December 2005

Higher-harmonics generation in a tapping-mode atomic force microscope is a consequence of the nonlinear tip-sample interaction force. The higher harmonics contain important information about the materials’ nanomechanical properties. These harmonics can be significantly enhanced by driving the cantilever close to a submultiple of its resonant frequency. We present the results of enhanced higher-harmonic imaging experiments on several samples. The results indicate that enhanced higher harmonics can be utilized effectively for both material characterization and surface roughness analysis with a high signal-to-noise ratio.
Wildfires, complexity, and highly optimized tolerance
Authors: Moritz Max A. , Morais Marco E. , Summerell Lora A. , Carlson J. M. , Doyle John
Published: December 2005

Recent, large fires in the western United States have rekindled debates about fire management and the role of natural fire regimes in the resilience of terrestrial ecosystems. This real-world experience parallels debates involving abstract models of forest fires, a central metaphor in complex systems theory. Both real and modeled fire-prone landscapes exhibit roughly power law statistics in fire size versus frequency. Here, we examine historical fire catalogs and a detailed fire simulation model; both are in agreement with a highly optimized tolerance model. Highly optimized tolerance suggests robustness tradeoffs underlie resilience in different fire-prone ecosystems. Understanding these mechanisms may provide new insights into the structure of ecological systems and be key in evaluating fire management strategies and sensitivities to climate change.
Scales of benthic–pelagic coupling and the intensity of species interactions: From recruitment limitation to top-down control
Authors: Navarrete Sergio A. , Wieters Evie A. , Broitman Bernardo R. , Castilla Juan Carlos
Published: December 2005

Large and usually unpredictable variation in species interaction strength has been a major roadblock to applying local experimental results to large-scale management and conservation issues. Recent studies explicitly considering benthic-pelagic coupling are starting to shed light on, and find regularities in, the causes of such large-scale variation in coastal ecosystems. Here, we evaluate the effects of variation in wind-driven upwelling on community regulation along 900 km of coastline of the southeastern Pacific, between 29°S and 35°S during 72 months. Variability in the intensity of upwelling occurring over tens of km produced predictable variation in recruitment of intertidal mussels, but not barnacles, and did not affect patterns of community structure. In contrast, sharp discontinuities in upwelling regimes produced abrupt and persistent breaks in the dynamics of benthic and pelagic communities over hundreds of km (regional) scales. Rates of mussel and barnacle recruitment changed sharply at ≈32°-33°S, determining a geographic break in adult abundance of these competitively dominant species. Analysis of satellite images demonstrates that regional-scale discontinuities in oceanographic regimes can couple benthic and pelagic systems, as evidenced by coincident breaks in dynamics and concentration of offshore surface chlorophyll-
a
. Field experiments showed that the paradigm of top-down control of intertidal benthic communities holds only south of the discontinuity. To the north, populations seem recruitment-limited, and predators have negligible effects, despite attaining similarly high abundances and potential predation effects across the region. Thus, geographically discontinuous oceanographic regimes set bounds to the strength of species interactions and define distinct regions for the design and implementation of sustainable management and conservation policies.
Phenogenetic drift in evolution: The changing genetic basis of vertebrate teeth
Authors: Kawasaki Kazuhiko , Suzuki Tohru , Weiss Kenneth M.
Published: December 2005

Vertebrate mineralized tissues are vital to the adaptive evolution of various traits. Among these traits is the tooth, which consists of two characteristic mineralized tissues, a highly mineralized surface layer (enamel in tetrapods and enameloid in fish) and a softer body (dentin), both supported by basal bone. However, enamel and enameloid are significantly different in development, and dentin shows many histological variations; hence their evolution has been intensively studied. Nevertheless, their genetic basis has been revealed only in tetrapods. We previously reported that many genes involved in tetrapod tissue mineralization arose from a common ancestor and constitute the secretory calcium-binding phosphoprotein (SCPP) gene family. Now we show that teleost fish also use many SCPPs for enameloid and dentin mineralization, but none of these directly corresponds to tetrapod SCPPs. This finding suggests that teleost and tetrapodSCPPgenes have experienced independent parallel duplication histories. Thus, through phenogenetic drift, the tooth has remained a stable trait in jawed vertebrates, while evolving distinct genetic bases in teleosts and tetrapods. The characteristics of teleostSCPPgenes and their expression domains in tooth development suggest the possibility that enameloid arose from dentin and enamel from enameloid more than once in vertebrate evolution. In fugu (puffer fish), expression ofSCPPgenes is also detected in an unusual beak-like structure that shelters numerous teeth. Their expression pattern suggests that the jaw consists of the dentin beak and supportive bone. These findings illustrate the complexity of the homology concept in understanding evolution, particularly the evolution of mineralized tissues.
The effect of nitrogen fertilizer application to maize and sorghum on the bionomics of Chilo partellus (Lepidoptera: Crambidae) and the performance of its larval parasitoid Cotesia flavipes (Hymenoptera: Braconidae)
Authors: Jiang N. , Schulthess F.
Published: December 2005

Laboratory and field trials were conducted to evaluate the effect of plant species (maize, sorghum), plant age (young, middle, old) and four different nitrogen fertilization levels (N0–N3) on the bionomics of the invasive crambid Chilo partellus and the performance of its braconid larval parasitoid Cotesia flavipes. Plant N varied significantly between N0 and N1–N3, but the differences among the latter were not significant. Intrinsic rates of increase and net-reproductive rates of C. partellus followed the same trends: they were lowest with N0 and similar among the other treatments. On maize only, mortality of C. partellus and parasitism by C. flavipes tended to decrease with age of the plant while the percentage of borers reaching adulthood (i.e. pupation) increased. Borer mortality and parasitism was lower and pupation higher on sorghum than on maize. On both host plants, percent dry matter content of frass, which could affect ingress of the parasitoid into the borer tunnel, did not vary with nitrogen level but varied with age of the host plants: on maize, it was highest on young plants and on sorghum on old plants. Tunnels were shorter on young maize and sorghum plants; longer tunnels on older plants indicated compensatory feeding by the larva as a result of lower nutritive value of the food source. Consequently, larval weight was lower on older than younger plants. The level of nitrogen fertilization had no effect on food conversion efficiency of C. partellus. Nitrogen did not affect number of C. flavipes progeny while egg load of progeny increased significantly with nitrogen level, on both plant species. Differences in egg load between sorghum and maize were mostly not significant. It was concluded that on depleted soils only, an increase in nitrogen via mulching, rotation with a leguminous crop or fertilization would increase survival of C. partellus on both maize and sorghum and an increase in acreage of maize and in application of nitrogen fertilizer in an area would also increase the parasitism of C. flavipes.
The invasive coconut mite Aceria guerreronis (Acari: Eriophyidae): origin and invasion sources inferred from mitochondrial (16S) and nuclear (ITS) sequences
Authors: Navia D. , de Moraes G.J. , Roderick G. , Navajas M.
Published: December 2005

Over the past 30 years the coconut mite Aceria guerreronis Keifer has emerged as one of the most important pests of coconut and has recently spread to most coconut production areas worldwide. The mite has not been recorded in the Indo-Pacific region, the area of origin of coconut, suggesting that it has infested coconut only recently. To investigate the geographical origin, ancestral host associations, and colonization history of the mite, DNA sequence data from two mitochondrial and one nuclear region were obtained from samples of 29 populations from the Americas, Africa and the Indo-ocean region. Mitochondrial DNA 16S ribosomal sequences were most diverse in Brazil, which contained six of a total of seven haplotypes. A single haplotype was shared by non-American mites. Patterns of nuclear ribosomal internal transcribed spacer (ITS) variation were similar, again with the highest nucleotide diversity found in Brazil. These results suggest an American origin of the mite and lend evidence to a previous hypothesis that the original host of the mite is a non-coconut palm. In contrast to the diversity in the Americas, all samples from Africa and Asia were identical or very similar, consistent with the hypothesis that the mite invaded these regions recently from a common source. Although the invasion routes of this mite are still only partially reconstructed, the study rules out coconut as the ancestral host of A. guerreronis, thus prompting a reassessment of efforts using quarantine and biological control to check the spread of the pest.
Genetic differentiation in Scottish populations of the pine beauty moth, Panolis flammea (Lepidoptera: Noctuidae)
Authors: Lowe A.J. , Hicks B.J. , Worley K. , Ennos R.A. , Morman J.D. , Stone G. , Watt A.D.
Published: December 2005

Pine beauty moth, Panolis flammea (Denis & Schiffermüller), is a recent but persistent pest of lodgepole pine plantations in Scotland, but exists naturally at low levels within remnants and plantations of Scots pine. To test whether separate host races occur in lodgepole and Scots pine stands and to examine colonization dynamics, allozyme, randomly amplified polymorphic DNA (RAPD) and mitochondrial variation were screened within a range of Scottish samples. RAPD analysis indicated limited long distance dispersal (FST = 0.099), and significant isolation by distance (P < 0.05); but that colonization between more proximate populations was often variable, from extensive to limited exchange. When compared with material from Germany, Scottish samples were found to be more diverse and significantly differentiated for all markers. For mtDNA, two highly divergent groups of haplotypes were evident, one group contained both German and Scottish samples and the other was predominantly Scottish. No genetic differentiation was evident between P. flammea populations sampled from different hosts, and no diversity bottleneck was observed in the lodgepole group. Indeed, lodgepole stands appear to have been colonized on multiple occasions from Scots pine sources and neighbouring populations on different hosts are close to panmixia.
Assessment of cross-resistance potential to neonicotinoid insecticides in Bemisia tabaci (Hemiptera: Aleyrodidae)
Authors: Prabhaker N. , Castle S. , Henneberry T.J. , Toscano N.C.
Published: December 2005

Laboratory bioassays were carried out with four neonicotinoid insecticides on multiple strains of Bemisia tabaci (Gennadius) to evaluate resistance and cross-resistance patterns. Three imidacloprid-resistant strains and field populations from three different locations in the southwestern USA were compared in systemic uptake bioassays with acetamiprid, dinotefuran, imidacloprid and thiamethoxam. An imidacloprid-resistant strain (IM-R) with 120-fold resistance originally collected from Imperial Valley, California, did not show cross-resistance to acetamiprid, dinotefuran or thiamethoxam. The Guatemala-resistant strain (GU-R) that was also highly resistant to imidacloprid (RR = 109-fold) showed low levels of cross-resistance when bioassayed with acetamiprid and thiamethoxam. However, dinotefuran was more toxic than either imidacloprid or thiamethoxam to both IM-R and GU-R strains as indicated by low LC50s. By contrast, a Q-biotype Spanish-resistant strain (SQ-R) of B. tabaci highly resistant to imidacloprid demonstrated high cross-resistance to the two related neonicotinoids. Field populations from Imperial Valley (California), Maricopa and Yuma (Arizona), showed variable susceptibility to imidacloprid (LC50s ranging from 3.39 to 115 μg ml–1) but did not exhibit cross-resistance to the three neonicotinoids suggesting that all three compounds would be effective in managing whiteflies. Yuma populations were the most susceptible to imidacloprid. Dinotefuran was the most toxic of the four neonicotinoids against field populations. Although differences in binding at the target site and metabolic pathways may influence the variability in cross-resistance patterns among whitefly populations, comparison of whitefly responses from various geographic regions to the four neonicotinoids indicates the importance of ecological and operational factors on development of cross-resistance to the neonicotinoids.
Evolutionary significance of promiscuity in an aphidophagous ladybird, Propylea dissecta (Coleoptera: Coccinellidae)
Authors: Omkar  , Mishra G.
Published: December 2005

The short- and long-term consequences of monogamy and promiscuity in an aphidophagous ladybird, Propylea dissecta (Mulsant) in terms of reproductive performance and offspring fitness were investigated. Promiscuous females were more fecund and laid more viable eggs than monogamous ones. Amongst promiscuous females, those mated with multiple males (freedom for mate choice) had significantly higher reproductive output than those mated daily with a new unmated male. The increased reproductive output of females mated with an unmated male each day in comparison to monogamous ones might possibly be a result of their increased ejaculate size. The further increase in reproductive output, when a female was allowed to choose a mate, may be because of repeated preferential mating with the fitter males. Results on long-term consequences of promiscuity revealed faster development and increased survival in offspring of promiscuous females at 25, 27 and 30%C. The percent adult emergence was more strongly influenced than development by the mating regime. There were no statistically significant differences in survival of offspring of promiscuous females (mate choice) at the three temperatures, while the percent survival of offspring of monogamous females differed significantly. Offspring of promiscuous females (mate choice) were fittest in terms of development and survival, which indicates their probable better genetic constitution and subsequently that of chosen mates. Thus, promiscuity has both short- and long-term benefits and is advantageous to ladybirds. The presence of long-term benefits in terms of fitter offspring probably indicates the evolutionary rationale behind the prevalence of promiscuity in ladybirds.
The influence of host suitability on the range of grasshopper species utilized by Blaesoxipha atlanis (Diptera: Sarcophagidae) in the field
Authors: Danyk T. , Mackauer M. , Johnson D.L.
Published: December 2005

Blaesoxipha atlanis (Aldrich) is a common parasitic fly of agriculturally important grasshoppers in Canada. The suitability of Camnula pellucida (Scudder), Melanoplus bivittatus (Say), Melanoplus packardii Scudder, and Melanoplus sanguinipes (Fabricius) as hosts was studied in the laboratory. Grasshoppers were singly-parasitized or left unparasitized and reared for 9 days. Melanoplus bivittatus and M. packardii did not support parasite development, i.e. were non-permissive hosts. In both species, parasite larvae were melanized and encapsulated, but development proceeded further in M. packardii. Melanoplus sanguinipes and C. pellucida were permissive host species with, respectively, 70% and 35% of the implanted larvae emerging from their hosts of which 86% and 50% developed into adults. Parasite development time was longer in C. pellucida. Adult B. atlanis dry mass varied with host species and host mass at parasitism, but not with host sex. Parasites developing in M. sanguinipes were larger in terms of dry mass than counterparts developing in C. pellucida. In permissive species, unparasitized grasshoppers gained in body mass while parasitized insects lost mass during the 9-day observation period. In non-permissive species, all insects gained in body mass, but parasitized females gained less mass than unparasitized conspecifics. All unparasitized grasshoppers survived while 75–95% of permissive and 30–40% of non-permissive hosts died. Variation in the intensity of field parasitism among grasshopper species may be explained, at least in part, by qualitative differences in suitability between potential host species. Novel pest management strategies emphasize preservation of a small proportion of the pest population for natural enemies. Consideration of the outcome of specific host-parasite interactions should improve the understanding of grasshopper population dynamics and increase the predictive value of models that assess potential crop losses.
Bioactive fractions containing methyl eugenol-derived sex pheromonal components in haemolymph of the male fruit fly Bactrocera dorsalis (Diptera: Tephritidae)
Authors: Hee A.K.W. , Tan K.H.
Published: December 2005

Sex pheromonal components of the tephritid fruit fly Bactrocera dorsalis (Hendel), 2-allyl-4,5-dimethoxyphenol and (E)-coniferyl alcohol, are biosynthesized from a highly potent male attractant, methyl eugenol, then sequestered and stored in the rectal gland prior to their release during courtship at dusk. These sex pheromonal components have been detected in the haemolymph and crop organ. Hence, attempts were made to separate and identify the haemolymph fractions which contained the sex pheromonal components. Identification of these bioactive fractions in methyl eugenol-fed male flies using gel filtration column chromatography and biodetection using live male flies showed two fractions as highly attractive to conspecific males. These fractions show a significant increase in protein absorbance in the elution profile of haemolymph from methyl eugenol-fed males compared with that from methyl eugenol-deprived males. The molecular mass of these bioactive fractions as determined by using gel filtration was in the peptide range of 3.3 to 5.5 kDa. Subsequent gas chromatography–mass spectrometry analyses further confirmed the presence of the pheromonal components in the bioactive fractions. The presence of these methyl eugenol-derived sex pheromonal components in specific haemolymph fractions suggests the involvement of a sex pheromone binding complex.
Phenology and demography of Homalodisca coagulata (Hemiptera: Cicadellidae) in southern California citrus and implications for management
Authors: Castle S.J. , Naranjo S.E. , Bi J.L. , Byrne F.J. , Toscano N.C.
Published: December 2005

Populations of Homalodisca coagulata (Say) were sampled from citrus orchards in southern California, USA to characterize and quantify seasonal occurrences of nymphs and adults with the goal of identifying management opportunities through well-timed treatments and/or natural enemy releases. Higher densities of H. coagulata in 2001 contributed to a complete seasonal profile that began in early spring with the emergence of first instar nymphs and their progression through five nymphal instars lasting until mid-August. Adult emergence began in mid-June with peak adult densities attained from mid to late August followed by a gradual decline through autumn. A persistent and significant male bias was observed in the adult sex ratio from the time of first emergence through mid-October in oranges; the same trend was present in lemons, but with more variability. Adult densities gradually declined through the winter months into the following spring before rapidly increasing again in June as the 2002 spring generation of nymphs began emerging as adults. The seasonal timing of nymphs and adults in 2002 was nearly identical to that observed the previous year. Phenology data from both years were incorporated into a stochastic, temperature-dependent model that predicts the occurrences of H. coagulata stages through time. Applications of imidacloprid early in the spring generation of nymphs proved very effective at reducing nymphs and sustaining lower densities of adults through summer.
The nutrition transition and its health implications in lower-income countries
Authors: Popkin Barry M
Published: December 2005

Objective:

This article reviews information on the rapid changes in diet, activity and body composition that lower- and middle-income countries are undergoing and then examines some of the potential health implications of this transition.

Design and Setting:

Data came from numerous countries and also from national food balance (FAOSTAT) and World Bank sources. Nationally representative and nationwide surveys are used. The nationally representative Russian Longitudinal Monitoring Surveys from 1992–96 and the nationwide China Health and Nutrition Survey from 1989–93 are examined in detail.

Results:

Rapid changes in the structure of diet, in particular associated with urbanization, are documented. In addition, large changes in occupation types are documented. These are linked with rapid increases in adult obesity in Latin America and Asia. Some of the potential implications for adult health are noted.

Conclusions:

The rapid changes in diet, activity and obesity that are facing billions of residents of lower- and middle-income countries are cause for great concern. Linked with these changes will be a rapid increase in chronic diseases. Little to date has been done at the national level to address these problems.
Feast and famine: Socioeconomic disparities in global nutrition and health
Authors: Darnton-Hill I , Coyne ET
Published: December 2005

Objective:

To review current information on under- and over-malnutrition and the consequences of socioeconomic disparities on global nutrition and health.

Design:

Malnutrition, both under and over, can no longer be addressed without considering global food insecurity, socioeconomic disparity, both globally and nationally, and global cultural, social and epidemiological transitions.

Setting:

The economic gap between the more and less affluent nations is growing. At the same time income disparity is growing within most countries, both developed and developing. Concurrently, epidemiological, demographic and nutrition transitions are taking place in many countries.

Results:

Fully one-third of young children in the world's low-income countries are stunted because of malnutrition. One-half of all deaths among young children are, in part, a consequence of malnutrition. Forty per cent of women in the developing world suffer from iron deficiency anaemia, a major cause of maternal mortality and low birth weight infants. Despite such worrying trends, there have been significant increases in life expectancy in nearly all countries of the world, and continuing improvements in infant mortality rates. The proportion of children malnourished has generally decreased, although actual numbers have not in sub-Saharan Africa and south Asia. Inequalities are increasing between the richest developed countries and the poorest developing countries. Social inequality is an important factor in differential mortality in both developed and developing countries. Many countries have significant pockets of malnutrition and increased mortality of children, while obesity and non-communicable disease (NCDs) prevalences are increasing. Not infrequently it is the poor and relatively disadvantaged sectors of the population who are suffering both. In the industrialized countries. cardiovascular disease incidence has declined, but less so in the poorer socioeconomic strata.

conclusions:

The apparent contradicitions found represent a particular point in time (population responses generally lag behind social and environmental transitions). They do also show encouraging evidence that interventions can have a positive impact, sometimes despite disadvantageous circumstances. However, it seems increasingly unlikely that food production will continue to keep up with population growth. It is also unlikely present goals for reducing protein-energy malnutrition prevalence will be reached. The coexistence of diseases of undernutrition and NCDs will have an impact on allocation of resources. Action needs to be continued and maintained at the international, national and individual level.
Mortality in vegetarians and non-vegetarians: a collaborative analysis of 8300 deaths among 76,000 men and women in five prospective studies
Authors: Key Timothy J , Fraser Gary E , Thorogood Margaret , Appleby Paul N , Beral Valerie , Reeves Gillian , Burr Michael L , Chang-Claude Jenny , Frentzel-Beyme Rainer , Kuzma Jan W , Mann Jim , McPherson Klim
Published: December 2005

Objective:

To compare the mortality rates of vegetarians and non-vegetarians.

Design:

Collaborative analysis using original data from five prospective studies. Death rate ratios for vegetarians compared to non-vegetarians were calculated for ischaemic heart disease, cerebrovascular disease, cancers of the stomach, large bowel, lung, breast and prostate, and for all causes of death. All results were adjusted for age, sex and smoking. A random effects model was used to calculate pooled estimates of effect for all studies combined.

Setting:

USA, UK and Germany.

Subjects:

76, 172 men and women aged 16–89 years at recruitment. Vegetarians were those who did not eat any meat or fish (n = 27,808). Non-vegetarians were from a similar background to the vegetarians within each study.

Results:

After a mean of 10.6 years of follow-up there were 8330 deaths before the age of 90 years, including 2264 deaths from ischaemic heart disease. In comparison with non-vegetarians, vegetarians had a 24% reduction in mortality from ischaemic heart disease (death rate ratio 0.76, 95% CI 0.62–0.94). The reduction in mortality among vegetarians varied significantly with age at death: rate ratios for vegetarians compared to non-vegetarians were 0.55 (95% CI 0.35—0.85), 0.69 (95% CI 0.53–0.90) and 0.92 (95% CI 0.73–1.16) for deaths from ischaemic heart disease at ages <65, 65–79 and 80–89 years, respectively. When the non-vegetarians were divided into regular meat eaters (who ate meat at least once a week) and semi-vegetarians (who ate fish only or ate meat less than once a week), the ischaemic heart disease death rate ratios compared to regular meat eaters were 0.78 (95% CI 0.68–0.89) in semi-vegetarians and 0.66 (95% CI 0.53–0.83) in vegetarians (test for trend P<0.001). There were no significant differences between vegetarians and non-vegetarians in mortality from the other causes of death examined.

Conclusion:

Vegetarians have a lower risk of dying from ischaemic heart disease than non-vegetarians.
Schoolchildren's diets and participation in school feeding programmes in Jamaica
Authors: Walker Susan P , Powell Christine A , Hutchinson Sharmaine E , Chang Susan M , Grantham-McGregor Sally M
Published: December 2005

Objective:

To describe food consumption during the school day of rural Jamaican children and participation in two government school feeding programmes. To determine factors which were related to these.

Design:

Cross sectional.

Setting:

16 primary schools in rural Jamaica.

Subjects:

415 children in grades 2 and 5 (ages 7 and 10 years).

Results:

Consumption of sweets, sweet drinks and snacks was high. Mean intakes at lunch were: energy 1537 kJ (SD 756), protein 10.4 g (SD 7.6) and iron 1.5 mg (SD 1.2). The mean energy intake was 17–20% of the daily requirement for this age group. Two types of school feeding programmes were available in the schools, one provided a cooked meal and the other a bun and milk. Median availability of school meals (as a percentage of children enrolled in the schools) over three terms was 24.6% (range 0–85.4%). Twenty per cent of the children participated in one or other programme. Poorer children were more likely to participate in the bun and milk programme (odds ratio 2.1, 95% C1 1.3–3.5) but children with more money to purchase food participated in the more costly cooked meal programme (odds ratio 2.4, 95% CI 1.3–4.6).

Conclusions:

Energy intakes at lunch in Jamaican children were somewhat below optimal levels and the reliance on sweets and snacks is an area of concern. Programme characteristics such as meal cost, may affect access to school feeding by poor children.
Metabolic and hormonal aspects of bovine ketosis and pregnancy
toxaemia in the ewe
Authors: Patterson D. S. P. , Cunningham N. F.
Published: December 2005

Metabolic fuels of the ruminant consist mainly of volatile fatty acids
produced in the rumen by microbial digestion of dietary polysaccharides and
amino acids derived from dietary protein. As almost no glucose is obtained
directly from its food, any specific requirements for this sugar are met by
synthesizing it from non-carbohydrate sources: principally propionate and
the glucogenic amino acids.
Mycotoxins in ruminants
Authors: Lancaster M. C.
Published: December 2005

Mycotoxins have for long been associated with disease and death in animals,
but because of the great variety of fungi present in animal feedstuffs and
the detailed investigations needed to establish a causal relationship
between mycotoxin and a clinical disease, few disease syndromes have been
identified.

In this paper, it is proposed to consider three confirmed clinical diseases
caused by mycotoxins, to review briefly their history and identification and
to consider their biological effects in ruminants.
Chairman’s opening remarks
Authors: Cuthbertson W. F. J.
Published: December 2005

An international group (Advisory Committee on the Application of Science and
Technology to Development, 1968) has stated that ‘The protein gap in the
nutrition of the population of our planet is becoming a most important
scientific, technological and health problem and a national and
international policy issue. The Governments of developing countries should
make every effort feasible to supply their populations as quickly as
possible with sufficient high quality food and to develop and apply the
necessary supporting science and technology in the fields of nutrition, food
science and technology’.
The absorption of protein from the intestine
Authors: Carpenter K. J.
Published: December 2005

This paper was prepared at very short notice and no written version will be
published.