bluuebunny/crossref_metadata_2025_split huggingface dataset:
Herbicides, glyphosate resistance and acute mammalian toxicity: simulating an environmental effect of glyphosate‐resistant weeds in the USA
Authors: Gardner Justin G , Nelson Gerald C 
Published: December 2007

AbstractBACKGROUND: With the emergence of glyphosate‐resistant (GR) weeds, the environmental consequences of alternatives to GR technology are of increasing importance. A well‐known acute mammalian toxicity measure, the LD50 dose for rats, is used to assess one potential environmental impact of the loss of GR technology. A new dataset with this index is used to estimate and simulate the effects for corn, soybeans and cotton.RESULTS: With conventional tillage it is found that the use of GR seeds reduces the number of LD50 doses applied per hectare by 17–98% depending on crop. With no‐till, the use of GR seeds reduces LD50 doses only in corn. If farmers switch to conventional seeds because of GR weeds but maintain the same tillage practice, the present simulations suggest that LD50 doses could increase by as much as 100 LD50 doses per hectare in soybeans, and 500 LD50 doses per hectare in cotton, or 11.4 and 19.8% respectively.CONCLUSIONS: This is the first study to use field‐level data to assess GR technology with a mammalian toxicity environmental indicator. It has been found that GR crops have a positive environmental effect, and that alternatives to GR technology increase toxicity. Copyright © 2007 Society of Chemical Industry
Inheritance of beta‐cypermethrin resistance in the housefly Musca domestica (Diptera: Muscidae)
Authors: Zhang Lan , Shi Jing , Gao Xiwu 
Published: December 2007

AbstractBACKGROUND: Beta‐cypermethrin, a synthetic pyrethroid insecticide, was applied frequently in the control of health pests including houseflies, Musca domestica L., in China. However, different levels of resistance to beta‐cypermethrin were monitored in field strains of houseflies. A strain of M. domestica, 4420‐fold resistant to beta‐cypermethrin after continuous 25 generations of selection, was used in this paper to determine the mode of inheritance of pyrethroid resistance.RESULTS: The estimated realized heritability (h2) of beta‐cypermethrin resistance was 0.30 in this resistant strain. Results of bioassays showed no significant difference in values of LD50 and slope of log dose‐probit lines between reciprocal progenies F1 and F′1, and yielded values of − 0.10 (F1) and − 0.11 (F′1) for the degree of dominance (D). Chi‐square analysis from responses of self‐bred and backcross progenies (F2, BC1 and BC2 respectively) indicated that the null hypothesis, a single gene responsible for resistance, was accepted. The minimum number of independent segregation genes was 0.93 for F1 by Lande's method.CONCLUSION: It was concluded that beta‐cypermethrin resistance in the housefly was inherited as a single, major, autosomal and incompletely recessive factor. These results would provide the basic information for pest management programmes. Copyright © 2007 Society of Chemical Industry
Understanding negative capacitance effect using an equivalent resistor‐capacitor circuit
Authors: Kwok H. L. 
Published: December 2007

AbstractNegative capacitance effect has been observed in disordered solids and is shown to be linked to the presence of traps. Thus far, few theories have been applied rigorously to the reported (negative capacitance) data in the literature. This work continues an earlier effort to study negative capacitance effect using the Drude model. We have extended the model and have correlated it with an equivalent circuit model consisting of a resistor and a capacitor. With this model, we have derived an equation for the negative capacitance and have shown that it exists when the real and the imaginary components of the complex conductance are roughly equal and have opposite signs. We have also computed the frequency at the negative capacitance peak and have shown that it is proportional to the complex conductance and hence the complex carrier mobility. It confirms our earlier hypothesis on the “universality of photocurrent transients” in disordered organic solids when the capacitance‐frequency curves are normalized with respect to bias and temperature. Based on our results, we confirm that the negative capacitance effect arises from time delay in the current flow related to the trapped carriers. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical characterisation of Sn doped InAs grown by MOVPE
Authors: Shamba P. , Botha L. , Krug T. , Venter A. , Botha J. R. 
Published: December 2007

AbstractThe feasibility of tetraethyl tin (TESn) as an n‐type dopant for InAs is investigated. The electrical properties of Sn doped InAs films grown on semi‐insulating GaAs substrates by MOVPE are extensively studied as a function of substrate temperature, V/III ratio, substrate orientation and TESn flow rate. Results from this study show that Sn concentrations can be controlled over 2 orders of magnitude. The Sn doped InAs layers exhibit carrier concentrations between 2.7 x 1017 and 4.7 x 1019 cm–3 with 77 K mobilities ranging from 12 000 to 1300 cm2/Vs. Furthermore, the influence of the variation of these parameters on the structural properties of InAs are also reported. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical characterization of InAs thin films
Authors: Botha L. , Shamba P. , Botha J. R. 
Published: December 2007

AbstractIt is known that parallel conduction as a result of surface and /or interface charge accumulation significantly shields the bulk electrical properties of InAs thin films when characterized using Hall measurements. This parallel conduction in InAs can be modeled by using the two‐layer model of Nedoluha and Koch [Zeitschrift für Physik 132, 608 (1952)]; where an InAs epilayer is treated as consisting of two conductors connected in parallel viz. a bulk and a surface layer. Here, this two‐layer model is used to simulate Hall coefficient and conductivity data of InAs thin films ranging from strongly n‐doped (n = 1018 cm–3) to strongly p‐doped (p ∼ 1019 cm–3) material. Conventional Hall approximations, i.e. those that assume uniform conduction from a single band, are then used to predict the apparent carrier concentration and mobility that will be determined from conventional Hall measurements, with the aim of illustrating the error of such a simplified analysis of InAs Hall data. Results show that, in addition to ignoring parallel conduction, the approximations of conventional Hall data analysis have a further inadequacy for p‐type InAs, in that the high electron to hole mobility ratio in InAs is not taken into account. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of ZnO thin films by second harmonic generation
Authors: Neethling P. H. , Rohwer E. G. , Bergmann H. M. Von , Stafast H. 
Published: December 2007

AbstractDifferent samples of ZnO thin films, manufactured using different techniques, namely metal organic chemical vapour deposition (MOCVD) and pulsed laser deposition (PLD) as well as a commercial bulk sample of ZnO were examined. SHG surface scan images of the samples were recorded measuring the SH signal in reflection. The information from these measurements can be used as a measure of the thickness and uniformity of the samples. Therefore SHG has potential as an in situ monitoring method during various manufacturing processes of ZnO thin films and thin film devices. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and characterization of GaAs‐GaSb III‐V pseudo‐binary nanoparticles
Authors: Schamp C. T. , Jesser W. A. 
Published: December 2007

AbstractThe GaAs‐GaSb pseudo‐binary materials system presents an interesting challenge for growth because of 1) the existence of a miscibility gap in the solid‐solid portion of the equilibrium phase diagram, and 2) the large differences in vapor pressure between the column III element, Ga, and the column V elements, As and Sb. To overcome these challenges in the growth of GaAs, GaSb, and Ga50AsxSb50–x alloy nanoparticles, single‐ and dual‐target pulsed laser deposition (PLD) techniques were implemented using an Nd:YAG laser operated with a harmonic generator to utilize the second harmonic wavelength (532 nm) and a combination of the fundamental and the second harmonic wavelengths (1064 nm + 532 nm). The nanoparticles were collected on amorphous carbon films for subsequent characterization by transmission electron microscopy. The analysis shows that single phase GaAs‐rich Ga50AsxSb50–x (28 > x > 50) nanoparticles and nanocrystalline films have been formed through dual‐target, single‐wavelength (532 nm) pulsed laser ablation. Interestingly, through the ablation of the single component targets, two‐phase particles were also found to form. These two phase particles resemble “nano‐ice cream cones” with solid cones of either GaAs or GaSb with a spherical “ice cream” ball of Ga located at the wide portion of the cone, which is either an amorphous phase or liquid phase. Through an analysis by STEM‐EDX spectroscopy, these particles are found to be consistant with this model. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the processing of InAs and InSb photodiode applications
Authors: Odendaal V. , Botha J. R. , Auret F. D. 
Published: December 2007

AbstractIn this paper, potential methods for the surface passivation of InSb and InAs material, covering both compositional extremes of the promising narrow band gap semiconductor InAsSb, are evaluated. Surface states, mostly due to dangling bonds and exposure to the atmosphere, create generation‐recombination centres that negatively influence the dark current, stability, efficiency and related noise characteristics of photosensitive devices fabricated from these materials. The effect of various surface treatments, including sulphuric acid based etching, lactic acid based etching, KOH anodising and Na2S anodising, on the relative number of surface states is deduced by evaluating the capacitance versus voltage characteristics of metal‐insulator‐semiconductor structures fabricated on InAs and InSb. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Grid‐based density functional calculations of many‐electron systems
Authors: Roy Amlan K. 
Published: December 2007

AbstractExploratory variational pseudopotential density functional calculations are performed for the electronic properties of many‐electron systems in the 3D cartesian coordinate grid (CCG). The atom‐centered localized gaussian basis set, electronic density, and the two‐body potentials are set up in the 3D cubic box. The classical Hartree potential is calculated accurately and efficiently through a Fourier convolution technique. As a first step, simple local density functionals of homogeneous electron gas are used for the exchange‐correlation potential, while Hay‐Wadt‐type effective core potentials are employed to eliminate the core electrons. No auxiliary basis set is invoked. Preliminary illustrative calculations on total energies, individual energy components, eigenvalues, potential energy curves, ionization energies, and atomization energies of a set of 12 molecules show excellent agreement with the corresponding reference values of atom‐centered grid as well as the grid‐free calculation. Results for three atoms are also given. Combination of CCG and the convolution procedure used for classical Coulomb potential can provide reasonably accurate and reliable results for many‐electron systems. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Bound state spectra of the 3D rational potential
Authors: Roy Amlan K. , Jalbout Abraham F. , Proynov Emil I. 
Published: December 2007

AbstractWe present bound state spectra of the 3D rational potential, V(r) = r2 + λr2/(1 + gr2), g > 0, by means of the generalized pseudospectral method. All the 30 states corresponding to n = 0–9 are considered for the first time for a broad range of coupling parameters. These results surpass the accuracy of all other existing calculations published so far except the finite‐difference method, which yields similar accuracy as ours. Variation of energies and radial distribution functions is followed with respect to the interaction parameters. Special emphasis has been laid on higher excitations and negative values of the interaction, where relatively less work has been reported. The energy sequence is found to be different for positive and negative interaction; numerically following a mirror‐image relationship usually, if not always. Additionally, 20 energy splittings arising from certain levels belonging to n = 0–9 are systematically studied as functions of the potential parameters. Several new states (including the higher ones) are presented. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
A civilization based on sustainable development: its limits and prospects
Authors: Skowroński Antoni 
Published: December 2007

AbstractSolutions to current environmental and social problems cannot be achieved on the basis of the traditional concept of development. One solution may be the idea of ‘sustainable development’, which presents a series of solutions leading to the protection and safeguarding of three thrusts to development, i.e. that of society (culture), of nature and of the economy. It assumes major modifications to our way of thinking – and to the means of civilizational development – pursued hitherto. It points to the need for the spiritual development of humankind, and for an exchange of the goals of development from the material centred to the non‐materialistic. With respect to these general assumptions and goals, sustainable development encounters many practical and psychological problems that curb (or even prevent) the effective incorporation of the concept in practice (the greatest single barrier is global unilateralism). Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.
On the benefits of diversity schemes for Bluetooth coverage extension in the presence of IEEE802.11g interference
Authors: Masini Barbara Mavì , Conti Andrea , Pasolini Gianni , Dardari Davide 
Published: December 2007

AbstractThis paper investigates the impact of diversity reception on the performance of Bluetooth (BT) packet transmission in wireless channels with fast fading and shadowing and in the presence of IEEE802.11g interference. In particular, selection diversity (SD) technique is considered and the adoption of this technique results in a coverage extension evaluated in the paper. We first derive a tight parametric exponential approximation for the instantaneous bit error probability (BEP) in additive white Gaussian noise (AWGN); then, from this expression, we derive the mean block error probability (BLEP) in Ricean fading channel by adopting a simple SD scheme. The analysis is then extended to the evaluation of the mean packet error probability (PEP) and the coverage probability (Pcov). In particular, the impact of the diversity order on the BLEP, PEP, andPcovis shown. Copyright © 2007 John Wiley & Sons, Ltd.
Energy and connectivity performance of routing groups in multi‐radio multi‐hop networks
Authors: Rossi Michele , Badia Leonardo , Giacon Paolo , Zorzi Michele 
Published: December 2007

AbstractThis paper explores the logical device aggregation of terminals in future generation networks, where the availability of several different radio access techniques is integrated by means of common radio resource management algorithms. In particular, we investigate the creation of routing groups (RGs) among adjacent nodes, which might be beneficial in order to improve connectivity, decrease signaling overhead and increase transmission efficiency. A simple analytical approach is proposed, which allows the performance evaluation of device aggregation algorithms. We measure the performance of establishing RGs with special focus on two metrics of interest: the connectivity of the nodes and the energy consumption. Within this framework, many detailed insights are obtained and presented throughout the paper. In particular, we focus on the effectiveness of these aggregation techniques in improving network connectivity and on the cost incurred in getting the extra information needed to build and maintain group structures. In the final part of the paper, we provide simulation results which further validate our discussion and highlight additional aspects that are to be considered in real scenarios. Our work is a first step in the investigation of the effectiveness of in‐network aggregation of terminals equipped with multiple radio technologies. The results derived in the paper are encouraging and motivate further research on the topic. Copyright © 2007 John Wiley & Sons, Ltd.
Forest edge creates small‐scale variation in reproductive rate of sika deer
Authors: Miyashita Tadashi , Suzuki Maki , Ando Daisuke , Fujita Go , Ochiai Keiji , Asada Masahiko 
Published: December 2007

AbstractHabitat edges are considered to have an important role in determining the abundance of deer in forest landscapes, but to our knowledge there are few lines of evidence indicating that forest edge enhances the vital rate of deer. We examined pregnancy of female sika deer in Boso peninsula, central Japan, and explored how forest edges, food availability in forests, and local population density influence the pregnancy rate of sika deer. Local deer density was estimated by the number of fecal pellets, and food availability in forests was estimated by combining GIS data of vegetation distribution and the relationship between vegetation biomass and local deer density. Forest edge length was also determined by GIS data. Model selection was performed with multiple logistic regression analyses using the AIC to find the best model for accounting for the observed variation in pregnancy rates of the deer. Multiple logistic regression analysis showed that the length of forest edge had a positive effect on the pregnancy rate of females, whereas food availability in forests and local deer density had little effect. This forest edge effect was detected in a 100–200‐m radius from deer captured locations, indicating that deer pregnancy is primarily determined by habitat quality within a 10‐ha area. This result was confirmed by tracking females with GPS telemetry, which found that the core areas of the home range were less than 12 ha. The positive effect of edges and the lack of density dependence could be a result of high plant productivity in open environments that produces forages not depleted by high deer densities. Our results support the view that land management is the cause of the current problem of deer overabundance.
Acidolysis of Tripalmitin with Oleic Acid Catalyzed by a Newly Isolated Thermostable Lipase
Authors: Guncheva M. , Zhiryakova D. , Radchenkova N. , Kambourova M. 
Published: December 2007

AbstractThe catalytic efficiency of a lipase from Bacillus stearothermophilus MC7 (lipase MC7) was evaluated in acidolysis of tripalmitin with oleic acid to yield dioleoylpalmitoylglycerol, a structured triglyceride used in health food. The immobilized enzyme exhibits good operational thermostability with a half‐life of 50 days at 60 °C in a solvent‐free system. The degree of conversion exceeded 50% after 48 h. The side reaction of hydrolysis was suppressed. However, the monosubstituted product was prevalent in the product mixture. Tested in a broad range of solvents, lipase MC7 showed tolerance towards medium polarity.
Exact analytic solutions for nonlinear waves in cold plasmas
Authors: ROWLANDS G. , BRODIN G. , STENFLO L. 
Published: December 2007

AbstractLarge amplitude plasma oscillations are studied in a cold electron plasma. Using Lagrangian variables, a new class of exact analytical solutions is found. It turns out that the electric field amplitude is limited either by wave breaking or by the condition that the electron density always has to stay positive. The range of possible amplitudes is determined analytically.
A Study Of Direct Severe Space Weather Effects On GPS Ionospheric Delay
Authors: Filjar Renato 
Published: December 2007

Severe space weather conditions affect the performance of numerous modern technical systems, causing problems not only for national and global economies, but for everyday life as well. Satellite navigation systems are particularly vulnerable, despite the fact that systematic monitoring of space weather in general is still performed on a global scale. Space weather effect correction models applied within the standard satellite positioning service are not capable of tackling the effects of severe space weather conditions and local ionospheric characteristics. Severe space weather effects on the GPS ionospheric delay are intensely studied in order to provide advanced models of the space weather effects on GPS positioning performance.Here one study of severe space weather conditions and its consequences on the GPS ionospheric delay in Croatia is presented. The study takes advantage of the availability of the space weather indices and the GPS pseudorange measurements (taken at the reference site at Osijek, Croatia) related to a major severe space weather event lasting from early October 2003 to late November 2003. This paper presents the reconstruction of the severe space weather conditions and the development of ionospheric disturbances. Based on these reconstructions, the dynamics of the GPS ionospheric delay has been derived. The comparison of actual (measured) and modelled (according to standard GPS model) GPS ionospheric delay has been performed, with the aims of identifying actual behaviour of GPS ionospheric delay and examining the ability of standard (Klobuchar) GPS model to describe the GPS ionospheric delay in severe space weather conditions. Two interesting experimental models derived from the data analysis are presented, addressing the direct relations between the GPS ionospheric delay and the parameters of space weather activity (sunspot number and solar flux), as observed at the reference station Osijek, Croatia.The paper concludes with the plans for further research activities related to the regional GPS ionospheric delay model development for south-eastern Europe.
Sexual dimorphism in campylobacteriosis
Authors: STRACHAN N. J. C. , WATSON R. O. , NOVIK V. , HOFREUTER D. , OGDEN I. D. , GALÁN J. E. 
Published: December 2007

SUMMARYSexual dimorphism in infectious diseases whereby disease incidence is more prevalent in one gender has been reported repeatedly in the scientific literature. Both behavioural and physiological differences have been suggested as a cause of this gender bias but there is a paucity of data to support either of these viewpoints. Here it is hypothesized that for campylobacteriosis physiological factors play an important role in the higher incidence in males. We demonstrate in the human population (from several countries in three continents) that this bias exists in young children (<1 year) where behavioural differences between genders are likely to be minimal. Further we demonstrate this difference in an animal model where both infection rates and shedding rates of the organism are greater in male mice.
Robert Mylne, Thomas Telford and the architecture of improvement: the planned villages of the British Fisheries Society, 1786–1817
Authors: MAUDLIN DANIEL 
Published: December 2007

ABSTRACTThis article examines the architecture and design of the pioneering planned fishing villages established by the British Fisheries Society across the Highlands of Scotland in the late eighteenth and early nineteenth centuries. The Society established a utilitarian planning model which fundamentally influenced the subsequent planned village boom that remains so evident in the historic landscape of the Scottish Highlands today. The British Fisheries Society also made a significant contribution to urban history with Thomas Telford's innovative plan for its last development of Pulteneytown. Pulteneytown remains the most complete example of Telford's work as a town planner.