bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy linkage between the singlet and triplet manifolds in LaH, and observation of new low-energy states
Authors: Mukund Sheo , Yarlagadda Suresh , Bhattacharyya Soumen , Nakhate S. G.
Published: December 2012

Wavelength-resolved fluorescence spectra of jet-cooled LaH were obtained from D1, E1, and 0+(3Σ−) states by exciting isolated rotational levels. The observation of a3Δ1 and a3Δ2 states at 1259.5(5) and 1646(1) cm−1, respectively, established the missing energy link between the singlet and triplet manifolds. The low-energy b3Π0,1 and B1Δ2 states predicted earlier from ab initio studies were also observed for the first time. Vibrational constants ωe = 1418(2) cm−1, ωexe = 15.6(7) cm−1 for the ground and ΔG1/2 = 1326.1(7) and 1312(1) cm−1, respectively, for the a3Δ1 and b3Π1 states were also determined. Vibrational frequencies were found to be in excellent agreement with earlier ab initio values. However, ab initio term energies and spin-orbit separation of 3Δ2-3Δ1 and 3Π1-3Π0 were found to be in poor agreement with the present observations. Also, the 3Π state that was predicted to be inverted is observed to be regular.
Terahertz absorption of dilute aqueous solutions
Authors: Heyden Matthias , Tobias Douglas J. , Matyushov Dmitry V.
Published: December 2012

Absorption of terahertz (THz) radiation by aqueous solutions of large solutes reports on the polarization response of their hydration shells. This is because the dipolar relaxation of the solute is dynamically frozen at these frequencies, and most of the solute-induced absorption changes, apart from the expulsion of water, are caused by interfacial water. We propose a model expressing the dipolar response of solutions in terms of a single parameter, the interface dipole moment induced in the interfacial water by electromagnetic radiation. We apply this concept to experimental THz absorption of hydrated sugars, amino acids, and proteins. None of the solutes studied here follow the expectations of dielectric theories, which predict a negative projection of the interface dipole on the external electric field. We find that this prediction is not able to describe the available experimental data, which instead suggests a nearly zero interface dipole for sugars and a more diverse pattern for amino acids. Hydrophobic amino acids, similarly to sugars, give rise to near zero interface dipoles, while strongly hydrophilic ones are best described by a positive projection of the interface dipole on the external field. The sign of the interface dipole is connected to the slope of the absorption coefficient with the solute concentration. A positive slope, implying an increase in the solution polarity relative to water, mirrors results frequently reported for protein solutions. We therefore use molecular dynamics simulations of hydrated glucose and lambda repressor protein to calculate the interface dipole moments of these solutes and the concentration dependence of the THz absorption. The absorption at THz frequencies increases with increasing solute concentration in both cases, implying a higher polarity of the solution compared to bulk water. The structure of the hydration layer, extracted from simulations, is qualitatively similar in both cases, with spatial correlations between the protein and water dipoles extending 4–5 nm into the bulk. The theory makes a testable prediction of the inversion of the positive slope at THz frequencies to a negative slope at lower frequencies of tens to hundreds of GHz.
Transport characteristics of a Glaser magnet for an axisymmetric and non-axisymmetric space charge dominated beam
Authors: Goswami A. , Sing Babu P. , Pandit V. S.
Published: December 2012

This paper describes the dynamics of space charge dominated beam through a Glaser magnet which is often used to focus charged particle beams in the low energy section of accelerators and in many other devices. Various beam optical properties of the magnet and emittance evolution that results from the coupling between the two transverse planes are studied. We have derived ten independent first order differential equations for the beam sigma matrix elements assuming the linear space-charge force consistent with the assumption of the canonically transformed KV like distribution. In addition, the feasibility of using a Glaser magnet doublet in a low energy beam injection line to match an initial non-axisymmetric high intensity beam with net angular momentum to an axisymmetric system to suppress effective emittance growth after transition back to an uncoupled system, has also been studied.
An intramolecular vibrationally excited intermolecular potential for He–OCS: Globally tested by simulation of vibrational shifts for OCS in HeN N = 1 − 100  Clusters
Authors: Li Hui , Ma Yong-Tao
Published: December 2012

An effective four-dimensional ab initio potential energy surface (PES) for He–OCS, which explicitly incorporates dependence on the intramolecular Q1 (O–C) stretch normal mode of OCS and is parametrically dependent on its Q3 (C–S) stretch coordinate has been calculated at the coupled-cluster single double triple/aug-cc-pVQZ level including bond functions. Analytic two-dimensional PESs are obtained by least-squares fitting vibrationally averaged interaction energies for v1(OCS)= 0, and 1 to the Morse/long-range potential function form. These fits to 305 points both have root-mean-square (rms) deviation of 0.022 cm−1, and require only 49 parameters. The resulting vibrationally averaged PESs provide good representations of the experimental microwave and infrared data: for 10 microwave transitions, and 51 infrared transitions of the He–OCS dimer, the rms discrepancies are only 93.2 MHz and 0.003 cm−1, respectively, which are more than four times better than previous theoretical predictions on their original ab initio potentials. The calculated infrared band origin shift associated with the v1 fundamental of OCS is blueshifted by 0.082 cm−1 for He–OCS dimer, which is in good agreement with the experimental value of 0.111 cm−1. The path integral Monte Carlo algorithm and a first order perturbation theory estimate are used to simulate the ν1 vibrational band origin frequency shifts of OCS in Hen clusters for  N = 1 − 100 . The predicted vibrational frequency shifts with first a blueshift for small N and then followed by a transition to a redshift for larger N are in excellent agreement with experiment across the whole range of N. These results for increasing N demonstrate the high quality of these potentials and globally test the accuracy not only the near global minimum, but also in regions not accessed by N = 1 He–OCS dimer.
Control of separated flow in a reflected shock interaction using a magnetically-accelerated surface discharge
Authors: Atkinson Michael D. , Poggie Jonathan , Camberos José A.
Published: December 2012

A numerical investigation was carried out to explore the effects of a magnetically-accelerated surface discharge on a separated, turbulent boundary layer in supersonic flow. The geometry and test conditions were chosen for comparison to experiments carried out at Princeton University. For those studies, a reflected shock interaction was created using a 14° shock generator acting on an incoming turbulent boundary layer with a Reynolds number based on momentum thickness of 1 × 104 and a freestream Mach number of 2.6. Three-dimensional, Reynolds-averaged, Navier-Stokes (RANS) calculations were carried out to simulate the experiments, using the US3D code developed at the University of Minnesota. The baseline code was modified to include a semi-empirical model of the surface discharge actuator, implemented through source terms in the momentum equation, vibrational energy equation, and total energy equation. The computational results for the baseline flow and several control cases were compared to experimental measurements of mean surface pressure. The level of discrepancy was typical of well-resolved RANS computations of three-dimensional, separated flows: qualitative agreement was obtained, and the general experimental trends were captured by the numerical model. Substantial three-dimensionality was observed even in the baseline flow, and significant changes in the flow topology were observed with the application of the actuator. Because of the highly three-dimensional nature of this shock interaction, the initial interpretation of the experiments may need to be revisited.
Theoretical aspects of pressure and solute denaturation of proteins: A Kirkwood-buff-theory approach
Authors: Ben-Naim Arieh
Published: December 2012

A new approach to the problem of pressure-denaturation (PD) and solute-denaturation (SD) of proteins is presented. The problem is formulated in terms of Le Chatelier principle, and a solution is sought in terms of the Kirkwood-Buff theory of solutions. It is found that both problems have one factor in common; the excluded volumes of the folded and the unfolded forms with respect to the solvent molecules. It is shown that solvent-induced effects operating on hydrophilic groups along the protein are probably the main reason for PD. On the other hand, the SD depends on the preferential solvation of the folded and the unfolded forms with respect to solvent and co-solvent molecules.
Polarization-dependent light-induced thermionic electron emission from carbon nanotube arrays using a wide range of wavelengths
Authors: Vahdani Moghaddam Mehran , Yaghoobi Parham , Nojeh Alireza
Published: December 2012

Light-induced thermionic electron emission from arrays of carbon nanotubes is observed using low-power, continuous-wave lasers with a broad set of wavelengths ranging from violet to infrared. The thermionic emission current is highest when the electric field of the laser is parallel to the axis of the nanotubes and lowest when it is perpendicular. The polarization dependence is stronger for the longer-wavelength beam.
Local ultra-violet surface photovoltage spectroscopy of single thread dislocations in gallium nitrides by Kelvin probe force microscopy
Authors: Liu Zhenghui , Xu Ke , Fan Yingmin , Xu Gengzhao , Huang Zengli , Zhong Haijian , Wang Jianfeng , Yang Hui
Published: December 2012

The local carrier properties, including minority diffusion lengths and surface recombination velocities, were measured at single thread dislocations in GaN film by a combination of surface photovoltage spectroscopy and Kelvin probe force microscopy. The thread dislocations introduced by a nanoindentation were observed as V-pits, where the photovoltage was lower than that on plane surface under ultra-violet illumination. A model is proposed to fit the spatially resolved surface photovoltage spectroscopy curves. Compared with those on plane surface, the hole diffusion length is 90 nm shorter and the surface electron recombination velocity is 1.6 times higher at an individual thread dislocation.
Communication: Nanoscale electrostatic theory of epistructural fields at the protein-water interface
Authors: Fernández Ariel
Published: December 2012

Nanoscale solvent confinement at the protein-water interface promotes dipole orientations that are not aligned with the internal electrostatic field of a protein, yielding what we term epistructural polarization. To quantify this effect, an equation is derived from first principles relating epistructural polarization with the magnitude of local distortions in water coordination causative of interfacial tension. The equation defines a nanoscale electrostatic model of water and enables an estimation of protein denaturation free energies and the inference of hot spots for protein associations. The theoretical results are validated vis-à-vis calorimetric data, revealing the destabilizing effect of epistructural polarization and its molecular origin.
A study of capping layers for sulfur monolayer doping on III-V junctions
Authors: Yum J. H. , Shin H. S. , Hill R. , Oh J. , Lee H. D. , Mushinski Ryan M. , Hudnall Todd W. , Bielawski C. W. , Banerjee S. K. , Loh W. Y. , Wang Wei-E , Kirsch Paul
Published: December 2012

Recently, high dosage doping on Si multi-gate field effect transistors and III–V planar structures using a self-limiting monolayer doping technique was reported to overcome challenges in scaling nano-sized transistors. The stoichiometry or composition of the capping layer was found to affect the diffusion efficiency of this process. In this work, we study the effect of a capping layer in sulfur monolayer doping on III–V junctions. Various capping temperatures and growth methods were compared. Based on the theoretical and experimental results, we suggest an optimized scheme consisting of a bi-layer capping structure. From Hall measurements and secondary ion mass spectrometry, a SiNx/BeO bi-layer capping, compared to single layer cap, exhibited the best results with a surface sheet resistance of 232 Ω/sq, junction depth of 11 nm, dopant profile abruptness of 3.5 nm/dec, electrically active S concentration of 4.9 × 1019/cm3 (=1.34 × 1013/cm2), and 3 times higher activation efficiency without significant transient-enhanced dopant diffusion.
Electron temperature anisotropy instabilities represented by superposition of streams
Authors: Inglebert A. , Ghizzo A. , Reveille T. , Bertrand P. , Califano F.
Published: December 2012

The generation of magnetic field, together with the electrostatic activity met in the saturation regime of the Weibel instability (WI), is investigated by means of an analytical multi-stream model in a Hamiltonian framework. Taking advantage from the invariance of the generalized canonical momentum, the model allows to reduce the full kinetic 1D2V Vlasov equation into several 1D1V equations while keeping its kinetic character. The multi-stream model provides a more complete and accurate picture of the Weibel instability, because it is possible to separate the specific contribution of each stream during the development of the Weibel instability. An interesting result for the multi-stream mode is a lower cost in the perpendicular treatment of the py momentum component since no differential operator associated with some approximate numerical scheme has to be carried out on this variable. Indeed, a small number of streams or particle classes are sufficient to correctly describe the magnetic field generation and the mixed electrostatic- electromagnetic nature of the instability.
Control methods of the switched reluctance motor in electric vehicle during acceleration
Authors: El Sayed Abdel-Kader Fathy , Elsherif M. Z. , Abdel-Rahim Naser M. B. , Fathy Mohamed M.
Published: December 2012

In this paper, the equations describing the performance of the electric vehicle are derived. Performance characteristics for each part in the vehicle system are obtained when the vehicle is accelerated under voltage, turn on, and turn off angle control. A comparison between the different methods of control is established. From these comparisons, it can be noticed that the acceleration time, for the case at which the turn on angle is controlled, will be smaller than that for the other cases; also the motor efficiency, at the voltage control method, has the highest value especially at the higher values of the vehicle speed.
Scanning photocurrent and photoluminescence imaging of a frozen polymer p-n junction
Authors: Inayeh Alex , Dorin Bryce , Gao Jun
Published: December 2012

A polymer light-emitting electrochemical cell (LEC) is a solid-state polymer device operating on in situ electrochemical doping and the formation of a light-emitting polymer p-n junction. Electrochemical doping of the luminescence polymer quenches the photoluminescence. The chemical potential difference between the p- and n-doped regions creates a built-in potential/field in the junction region, which can be probed by measuring the optical beam induced current (OBIC). In this study, the OBIC and photoluminescence profiles of the LEC have been simultaneously measured by scanning a focused light beam across a large planar LEC that has been turned on and cooled to freeze the doping profile. The photoluminescence intensity undergoes a sharp transition between the p- and n-doped regions. The OBIC photocurrent is only observed in the transition region that is narrower than the width of the excitation beam, which is about 35 μm. The results depict a static planar polymer p-n junction with a built-in field pointing from n to p. The electrode interface and the neutral regions do not produce a measurable photocurrent.
Dialysis is superior to anion exchange for removal of dissolved inorganic nitrogen from freshwater samples prior to dissolved organic nitrogen determination
Authors: Graeber Daniel , Gücker Björn , Zwirnmann Elke , Kronvang Brian , Weih Christoph , Gelbrecht Jörg
Published: December 2012

Environmental context
Aquatic ecosystem health may be adversely affected by dissolved organic nitrogen pollution, and accurate analytical techniques are needed to assess these effects. Our study shows that dialysis is the best sample pre-treatment technique to increase the accuracy of dissolved organic nitrogen determination. It will improve analysis and understanding of the role of dissolved organic nitrogen in the nitrogen cycle of affected aquatic ecosystems.

Abstract
Dissolved organic nitrogen (DON) is usually determined as the difference between total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN). When applying this approach to samples with high DIN concentrations, there is a risk that small relative errors in TDN and DIN measurements may propagate into high absolute errors of the determined DON concentration. To reduce such errors, two pre-treatment methods have been suggested for the removal of DIN before the determination of DON: anion-exchange pre-treatment (AEP) and dialysis pre-treatment (DP). In this study, we tested the suitability of AEP and DP for DIN removal in order to increase the accuracy of DON determination of freshwater samples. The AEP performed well for standard compounds, yielding high dissolved organic carbon (DOC) recovery rates and >99 % removal of nitrate, whereas DON recovery rates varied and no removal occurred for ammonium and nitrite. However, AEP proved not to be suitable for natural samples, as it removed 36–74 % DOC and up to 83 % DON. In contrast, after 72 h of DP, 17–32 % DOC and DON had been removed from the natural samples, whereas >98 % nitrate was removed in all but one case, and >87 % of the ammonium and nitrite were removed. Moreover, we found that DP results in a significant increase in DON determination accuracy. In conclusion, DP is a useful measure to increase DON determination accuracy in natural freshwater samples with high DIN-to-TDN ratios, whereas AEP is not recommended for DON determination of natural freshwater samples.
Effect of pH and environmental ligands on accumulation and toxicity of Ni2+ to Lemna minor
Authors: Gopalapillai Yamini , Vigneault Bernard , Hale Beverley
Published: December 2012

Environmental context Predicting metal toxicity is an important tool for effective and efficient risk assessment and regulation of metal pollution in the environment. The present study aims to provide scientific support for the development of a predictive Ni toxicity model for aquatic plants that is particularly applicable to mining-affected natural waters. We show that the effects of pH and natural organic ligands on Ni accumulation and toxicity can be modelled, but further research is required to understand the effects of flotation ligands used in the mining industry. Abstract Effects of water chemistry and metal speciation on metal uptake and toxicity to aquatic plants such as Lemna minor are not fully understood. The present study examined the effect of pH and environmental ligands (dissolved organic carbon (DOC) and mining related flotation ligands diethylenetriamine (DETA), triethylenetetramine (TETA), sodium isopropyl xanthate), on Ni toxicity to L. minor. Exposure and tissue residue toxicity thresholds were assessed to validate the use of a Biotic Ligand Model (BLM) or a Tissue Residue Approach (TRA) as a framework for predicting Ni toxicity. An increase in the activity of H+ non-linearly decreased the toxicity of free Ni ion activity, whereas Ni accumulation kinetics indicated that the mechanism of Ni2+ and H+ interaction was not competitive inhibition as expected by the BLM framework. The effect of DOC on the toxicity of total Ni concentration was relatively small (toxicity decreased by less than a factor of 2) and was explained solely by the complexation of Ni2+ by DOC. Alternatively, the protective effect of flotation ligands (DETA and TETA) was much less than expected based on estimated Ni complexation. Overall, a TRA model was directly applicable in the presence of organic ligands but not to varying pH, whereas a BLM-type model was applicable with changes in pH and DOC but not in the presence of the lesser studied flotation ligands. Such mechanistic information is essential for the development of reliable Ni toxicity models that would aid in risk assessment and regulation of Ni in the environment, particularly in mining-affected regions.
Photochlorination of aniline in Fe3+-containing saline water under simulated solar light irradiation
Authors: Wu Lei , Hu Xuefeng
Published: December 2012

Environmental context
Aromatic amines are widely used chemicals, which show enhanced toxicity and longer environmental persistence when halogenated. We investigated the chlorination of aniline in seawater and in natural aqueous solutions containing Fe3+ and Cl–, under simulated sunlight irradiation. The results increase our understanding of the transformation pathway of typical nitrogen-containing aromatic contaminants in the environment.

Abstract
Photochlorination of aniline was observed in aqueous solutions containing dissolved FeIII and chloride ions under simulated solar light irradiation. Effects of O2, Cl–, Fe3+ and pH on the formation of chloroanilines (CAs) were investigated. para-chloroaniline (4CA) was identified as the main chlorinated product. The formation of 4CA is enhanced with increased concentrations of Cl– or Fe3+, and decreased pH, whereas oxygen plays a negligible role in the process. The results indicate that, Cl• is formed mainly by the photodissociation of FeCl2+–FeCl2+ complexes, and reacts with Cl– to produce Cl2•–. Aniline is then oxidised by Cl2•– into an anilino radical cation, which further reacts with Cl2•– to generate CAs. The photochlorination of aniline in natural seawater was also observed. Other phototransformation products of aniline were detected and a transformation pathway was proposed. This work provides evidence for the photochemical chlorination path of aniline-based aromatic amines in aqueous solutions.
Caring for refugees in general practice: perspectives from the coalface
Authors: Farley Rebecca , Askew Deborah , Kay Margaret
Published: December 2012

This qualitative research project explored the experiences of primary health care providers working with newly arrived refugees in Brisbane. Data from 36 participants (20 general practitioners, five practice nurses and 11 administrative staff) involved in five focus groups and four semi-structured interviews were analysed. The results indicated that despite difficulties, providers are committed and enthusiastic about working with refugees. The flexibility of the general practice setting enables innovative approaches. The establishment of a specialised refugee health service in Brisbane has improved providers’ capacity to deliver refugee health care. However, most practices continue to feel isolated as they search for solutions, and the need for greater supports and a more coordinated approach to care were emphasised. The themes of communication, knowledge and practice and health care systems encapsulated the factors that influence health care providers’ ability to care for refugees and provide a framework for improving available supports. Australian primary health care is currently undergoing great change, which provides an opportunity to make significant gains in the provision of care for refugees and other minority groups within our community. As health care reforms are implemented it is essential that they are responsive to the expressed needs of health care providers working in these areas.
Impact of the Social Café Meals program: a qualitative investigation
Authors: Allen Louise , O'Connor Jacklin , Amezdroz Emily , Bucello Pieta , Mitchell Hannah , Thomas Arabella , Kleve Sue , Bernardi Anthony , Wallis Liza , Palermo Claire
Published: December 2012

Social Café Meals Programs aim to reduce food insecurity and social exclusion by providing participants access to subsidised meals in mainstream local cafés. This study aimed to explore the program’s ability to address social exclusion and food insecurity and the impact of the program on the community. A qualitative evaluation approach was utilised whereby in-depth interviews were conducted with café owners, café staff and current program members of two Social Café Meals Programs operating in the south-eastern suburbs of Melbourne. Twelve program members and six café staff completed an in-depth interview at the local cafés. Data were analysed using a thematic analysis approach focusing on the lived experience of the café owners, staff and program members. Four key themes were identified. The program (i) improved food access for vulnerable groups and (ii) created community cohesiveness. (iii) The café environment was important in facilitating program use by community members. (iv) Café owners felt rewarded for their community contribution via the program. Social Café Meals Programs may provide a solution to improving food security and reducing social exclusion and may be considered as a strategy for improving nutrition and social health for at-risk and vulnerable groups.
Does discussing sexually transmissible infections or HIV with a parent increase condom use among young women using other contraceptive methods?
Authors: Bradley Heather , Leichliter Jami S. , Gift Thomas L.
Published: December 2012

Background
Young people may be more likely to use condoms if they discuss sexual risks with their parents. However, no previous study has examined whether discussing sexual risks with a parent is differently associated with condom use among women using and not using other contraceptive methods. Methods: Using weighted data from the 2006–2008 National Survey of Family Growth, we examined condom use at last sex among 1206 sexually active unmarried women aged 15–24 years. Using logistic regression, we examined the association between condom use and discussing sexually transmissible infections (STIs) with parents before the age of 18 years, adjusted for women’s characteristics (age, ethnicity, income and condom use at first sex). We estimated the predicted probability of condom use by whether women discussed STIs with parents, stratified by use of other contraceptive methods. Results: Overall, 53% of women used condoms at last sex. Among 564 women using other contraceptives, 42% used condoms, versus 64% of 642 women not using other contraceptive methods (P < 0.01). After adjustment for covariates, the predicted probability of condom use among women using other contraceptives was 47% among women who discussed STIs with their parents (v. 31% of those not discussing STIs; P < 0.01). Among women not using other contraceptives, the predicted probability of condom use remained 64% regardless of whether they discussed STIs with their parents. Conclusions: Young women who use other contraceptive methods are less likely to use condoms, but discussing STIs with parents is associated with increased condom use among these women.
A review of sign language acquisition studies as the basis for informed decisions for sign language test adaptation
Authors: Haug Tobias
Published: December 2012

Developing or adapting tests of sign language development requires knowledge about the emergence and mastery of the linguistic structures that should be represented in a test. As the structures and acquisition of many sign languages are rather under-documented, developing or adapting a test for a specific sign language poses a great challenge for test developers, especially with respect to the test’s reliability and validity.

Deutsche Gebärdensprache

This paper presents this review of the most recent acquisition studies of the linguistic structures mentioned above and represented in the BSL test. The main focus is on studies that covered the age range of 4 to 8 year-olds, the age group of the adapted DGS test. The argument will be made that — considering the current state of research for many sign languages — these acquisition studies from a variety of sign languages can serve as the basis for making informed decisions for test development and adaptation (for example, deciding which items should be represented in a sign language test), but only together with cross-linguistic and language specific studies.
A Price Theory of Vertical and Lateral Integration*
Authors: Legros Patrick , Newman Andrew F.
Published: December 2012

This article presents a perfectly competitive model of firm boundary decisions and study their interplay with product demand, technology, and welfare. Integration is privately costly but is effective at coordinating production decisions; nonintegration is less costly but coordinates relatively poorly. Output price influences the choice of ownership structure: integration increases with the price level. At the same time, ownership affects output, because integration is more productive than nonintegration. For a generic set of demand functions, equilibrium delivers heterogeneity of ownership and performance among ex ante identical enterprises. The price mechanism transmutes demand shifts into industry-wide reorganizations and generates external effects from technological shocks: productivity changes in some firms may induce ownership changes in others. If the enterprise managers have full title to its revenues, market equilibrium ownership structures are second-best efficient. When managers have less than full revenue claims, equilibrium can be inefficient, with too little integration.
Development and Validation of a Real-Time PCR Assay for the Quantification ofVerticillium dahliaein Potato
Authors: Pasche J. S. , Mallik I. , Anderson N. R. , Gudmestad N. C.
Published: December 2012

An increase in the stringency for higher quality potato tubers and restrictions on the use of soil fumigants, among other factors, has garnered renewed interest in Verticillium wilt, particularly in russet-skinned cultivars grown for processing. In response to the needs of producers, breeders have increased efforts in the development of potato cultivars with resistance to Verticillium dahliae Kleb., the primary cause of Verticillium wilt. These efforts have resulted in the release of numerous russet-skinned cultivars with purported resistance to the pathogen. However, because efficient and effective methods to screen germplasm for true resistance do not exist, breeders typically have reported resistance based on the development of wilt symptoms alone. The studies reported here demonstrate the efficiency and practicality of a QPCR method for quantification of V. dahliae in potato stem tissue. This method, developed to detect the target trypsin protease gene of the pathogen, was compared with traditional methods for V. dahliae quantification which involve plating stem tissue or sap onto semi-selective media, as well as to a recently developed QPCR assay which amplifies a region of the β-tubulin gene of V. dahliae. The QPCR assay developed in the studies reported here was demonstrated to be sensitive to 0.25 pg of DNA. Use of the duplex real-time PCR assay, utilizing the potato actin gene to normalize quantification, resulted in clearer differentiation of levels of resistance among eight russet-skinned potato cultivars inoculated in greenhouse trials when compared with traditional plating assays. However, relative levels of resistance among cultivars were similar between traditional plating and QPCR methods, resulting in correlation coefficients greater than 0.93. The assay described here also detected the pathogen in inoculated stem tissue at higher frequencies than both traditional plating assays and a previously developed QPCR assay. The QPCR assay developed here demonstrates rapid, efficient, and accurate quantification of V. dahliae, providing a tool amenable for use by breeding programs on large numbers of clones and selections, and will aid researchers evaluating other control strategies for Verticillium wilt.
Reaction of Lines of the Rapid Cycling Brassica Collection and Arabidopsis thaliana to Four Pathotypes of Plasmodiophora brassicae
Authors: Sharma Kalpana , Gossen Bruce D. , Greenshields David , Selvaraj Gopalan , Strelkov Stephen E. , McDonald Mary Ruth
Published: December 2012

The clubroot reaction of five Rapid Cycling Brassica Collection (RCBC) lines (Brassica carinata, B. juncea, B. napus, B. oleracea, and B. rapa) and 84 lines of Arabidopsis thaliana to pathotypes 2, 3, 5, and 6 of Plasmodiophora brassicae (as classified on William's system) was assessed. Also, the reaction of the Arabidopsis lines to a single-spore isolate of each of pathotypes 3 and 6 was compared with that of a field isolate. Seedlings were inoculated with resting spores of P. brassicae, maintained at 25 and 20°C (day and night, respectively), and assessed for clubroot incidence and severity at 6 weeks after inoculation. Several lines of A. thaliana and RCBC exhibited a differential response to pathotype but none of the lines were immune. Among the RCBC lines, B. napus was resistant to all of the pathotypes; B. oleracea was resistant to pathotypes 2, 3, and 5; B. carinata and B. rapa were resistant to pathotypes 2 and 5; and B. juncea was susceptible to pathotypes 5 and 6 and had an intermediate response to pathotypes 2 and 3. Line Ct-1 of A. thaliana was highly resistant to pathotype 2, Pu2-23 was highly resistant to pathotype 5, and Ws-2 and Sorbo were highly resistant to pathotype 6. These results indicate that the lines of RCBC and A. thaliana have potential for use as model crops for a wide range of studies on clubroot, and could be used to differentiate these four pathotypes of P. brassicae. The reaction of the RCBC lines to pathotype 6 was highly correlated with response under field conditions but the reaction to the single-spore isolates of pathotypes 3 and 6 was not strongly correlated with reaction to the field collections in the Arabidopsis lines.
Replacement of conserved or variable sequences of the mosquito-borne dengue virus 3′ UTR with homologous sequences from Modoc virus does not change infectivity for mosquitoes
Authors: Tumban Ebenezer , Maes Nyree E. , Schirtzinger Erin E. , Young Katherine I. , Hanson Christopher T. , Whitehead Stephen S. , Hanley Kathryn A.
Published: December 2012

The genus Flavivirus includes both vector-borne and no known vector (NKV) species, but the molecular determinants of transmission mode are not known. Conserved sequence differences between the two groups occur in 5′ and 3′ UTRs. To investigate the impact of these differences on transmission, chimeric genomes were generated, in which UTRs, UTRs+capsid, or the upper 3′ UTR stem–loop of mosquito-borne dengue virus (DENV) were replaced with homologous regions from NKV Modoc virus (MODV); the conserved pentanucleotide sequence (CPS) was also deleted from the DENV genome. Virus was not recovered following transfection of these genomes in three different cell types. However, DENV genomes in which the CPS or variable region (VR) of the 3′ UTR were replaced with MODV sequences were recovered and infected Aedes aegypti mosquitoes with similar efficiencies to DENV. These results demonstrate that neither vector-borne CPS nor VR is required for vector-borne transmission.
From Stockholm to Malawi: recent developments in studying human polyomaviruses
Authors: Feltkamp Mariet C. W. , Kazem Siamaque , van der Meijden Els , Lauber Chris , Gorbalenya Alexander E.
Published: December 2012

Until a few years ago the polyomavirus family (Polyomaviridae) included a dozen viruses identified in avian and mammalian hosts. Two of these, the JC and BK-polyomaviruses isolated a long time ago, are known to infect humans and cause severe illness in immunocompromised hosts. Since 2007 an unprecedented number of eight novel polyomaviruses were discovered in humans. Among them are the KI- and WU-polyomaviruses identified in respiratory samples, the Merkel cell polyomavirus found in skin carcinomas and the polyomavirus associated with trichodysplasia spinulosa, a skin disease of transplant patients. Another four novel human polyomaviruses were identified, HPyV6, HPyV7, HPyV9 and the Malawi polyomavirus, so far not associated with any disease. In the same period several novel mammalian polyomaviruses were described. This review summarizes the recent developments in studying the novel human polyomaviruses, and touches upon several aspects of polyomavirus virology, pathogenicity, epidemiology and phylogeny.
Molecular evolution of Crimean–Congo hemorrhagic fever virus based on complete genomes
Authors: Chen Shuiping
Published: December 2012

Crimean–Congo hemorrhagic fever virus (CCHFV), which is widely distributed in parts of Asia, Africa and Europe, often causes fatal viral infections in humans. However, its evolutionary features are still unclear. In this study, a total of 22 global CCHFV strains with complete genome segments were analysed. Three medium (M) segment reassortants and two small (S) segment reassortants were newly identified. According to Bayesian analysis of the S, M and large (L) segment datasets with and without reassortants, inclusion of reassortants was approved to bias Bayesian analysis of the S and L segments, but not the M segment. The mucin domain of the M segment had no effect on evolutionary rate estimates, but had slight effects on the time to the most recent common ancestor. Selection pressure analysis suggested that CCHFV was under strong purifying selection regardless of the S, M and L segments, and that the L segment was also shaped by positive selection. Bayesian analysis in this study indicated the evolutionary features of CCHFV, which were helpful in investigating the molecular evolution, CCHF surveillance and the pathogenicity of CCHFV and other viruses in the family Bunyaviridae.
Submicrometre-resolution polychromatic three-dimensional X-ray microscopy
Authors: Larson B. C. , Levine L. E.
Published: December 2012

The ability to study the structure, microstructure and evolution of materials with increasing spatial resolution is fundamental to achieving a full understanding of the underlying science of materials. Polychromatic three-dimensional X-ray microscopy (3DXM) is a recently developed nondestructive diffraction technique that enables crystallographic phase identification, determination of local crystal orientations, grain morphologies, grain interface types and orientations, and in favorable cases direct determination of the deviatoric elastic strain tensor with submicrometre spatial resolution in all three dimensions. With the added capability of an energy-scanning incident beam monochromator, the determination of absolute lattice parameters is enabled, allowing specification of the complete elastic strain tensor with three-dimensional spatial resolution. The methods associated with 3DXM are described and key applications of 3DXM are discussed, including studies of deformation in single-crystal and polycrystalline metals and semiconductors, indentation deformation, thermal grain growth in polycrystalline aluminium, the metal–insulator transition in nanoplatelet VO2, interface strengths in metal–matrix composites, high-pressure science, Sn whisker growth, and electromigration processes. Finally, the outlook for future developments associated with this technique is described.
Characteristics of Cavitation Erosion Using Image Processing Techniques
Authors: Alturki F. A. , Abouel-Kasem A. , Ahmed S. M.
Published: December 2012

This paper deals with the analysis of eroded surfaces obtained from cavitation-erosion experiments on stainless steel in water and oil-in-water (o/w) emulsions using image processing. Two analysis techniques that are very promising in this respect are the wavelet decomposition transform and fractals. These can be used to extract parameters that characterize the cavitation intensity in a similar manner to that of the mean depth of erosion (MDP). The extracted parameters are the wavelet energy and entropy as well as the fractal dimension. Both of the image feature parameters and the MDP decrease with adding oil to water. Also, it was found that the variation of image feature parameters versus concentration of oil-in-water emulsions has a general trend that does not depend on magnification factor. The cavitation erosion behavior and mechanism for water and o/w emulsions were analyzed and it was found that the predominant failure mode was fatigue for water and o/w emulsions. The results show that a corrosive effect appears at 5 and 10 wt% o/w emulsions.
Tribological Properties of Stearic Acid Modified Multi-Walled Carbon Nanotubes in Water
Authors: Peng Yitian , Ni Zhonghua
Published: December 2012

The oxidized multiwalled carbon nanotubes (MWCNTs) were modified with stearic acid (SA) molecules. The SA-modified MWCNTs were characterized with scanning electron microscopy, transmission electron microscopy, and Fourier transform-infrared spectroscopy. The tribological properties of the oxidized and SA-modified MWCNTs as additives in water were comparatively investigated with a four-ball tester. The results showed the SA-modified MWCNTs in water have better tribological properties including friction reduction and antiwear than oxidized MWCNTs. The possible mechanism of SA-modified MWCNT as an additive in water was discussed. This research provides the opportunity for the lubricant application of MWCNTs.
Pelton Turbine Needle Control Model Development, Validation, and Governor Designs
Authors: Johnson Randell M. , Chow Joe H. , Dillon Michael V.
Published: December 2012

Underspeed needle control of two Pelton turbine hydro units operating in a small power system has caused many incidents of partial system blackouts. Among the causes are conservative governor designs with regard to small signal stability limits, nonminimum phase power characteristics, and long tunnel-penstock traveling wave effects. A needle control model is developed from “water to wires” and validated for hydro-turbine dynamics using turbine test data. Model parameters are tuned using a trajectory sensitivity method. In the governor design proposed here the needle regulation gains are distributed into the power and frequency governor loops with a multi-timescale approach. Elements of speed loop gain scheduling and a new inner-loop pressure stabilization circuit are devised to improve the frequency regulation and to damp the traveling wave effects. Simulation studies show the improvements of the proposed control designs.
Dynamic Behavior of a Large Ring of Coupled Self-Excited Oscillators
Authors: Barron Miguel A. , Sen Mihir
Published: December 2012

Interconnected, self-excited oscillators are often found in nature and in engineered devices. In this work, a ring of van der Pol oscillators, each of which is connected to its immediate neighbors, is considered. The focus is on the emergent behavior of a large number of oscillators. Conditions are determined under which time-independent solutions are obtained, and the linear stability of these solutions is investigated. The effect of the singularity of the coupling matrix on the ring dynamics is explored. When this becomes singular, an infinite number of steady states is present, and the phenomenon of oscillation death arises. It is also possible to have, depending on initial conditions, all oscillators with in-phase synchrony, metachronal traveling waves with different wavelengths going around the ring, or standing waves. Interconnected oscillators can propagate information at a group velocity, and the information signal is present as an amplitude modulation.
Nonlinear Dynamic Analysis of a Cracked Rotor-Bearing System With Fractional Order Damping
Authors: Cao Junyi , Xue Shiming , Lin Jing , Chen Yangquan
Published: December 2012

Fatigue cracking of the rotor shaft is an important fault observed in the rotating machinery of key industries, which can lead to catastrophic failure. Nonlinear dynamics of a cracked rotor system with fractional order damping is investigated by using a response-dependent breathing crack model. The fourth-order Runge–Kutta method and tenth-order continued fraction expansion-Euler (CFE-Euler) method are introduced to simulate the proposed system equation of fractional order cracked rotors. The effects of the derivative order of damping, rotating speed ratio, crack depth, orientation angle of imbalance relative to the crack direction, and mass eccentricity on the system dynamics are demonstrated by using a bifurcation diagram, Poincaré map, and rotor trajectory diagram. The simulation results show that the rotor system displays chaotic, quasi-periodic, and periodic motions as the fractional order increases. It is also observed that the imbalance eccentricity level, crack depth, rotational speed, fractional damping, and crack angle all have considerable influence on the nonlinear behavior of the cracked rotor system. Finally, the experimental results verify the effectiveness of the theoretical analysis.
Interfacial chemistry of hydrofluoric acid-treated In0.53Ga0.47As(100) during atomic layer deposition of aluminum oxide
Authors: Granados-Alpizar Bernal , Li Lie Fee , Muscat Anthony J.
Published: December 2012

Atomic layer deposition (ALD) of aluminum oxide on In0.53Ga0.47As(100) prepared with aqueous or gas phase hydrofluoric acid (HF) was followed using x-ray photoelectron spectroscopy after each pulse of trimethylaluminum (TMA, Al(CH3)3) and water at 170°C up to three cycles. On the surface prepared using aqueous HF, the primary oxide was As2O3, which was removed by the first TMA pulse depositing about two layers of AlOx and leaving residual As+1 oxide at the interface that persisted even after three complete ALD cycles. The aluminum oxide AlOx film was O deficient but was closed off, trapping the As+1 oxide at the interface. The C and O coverages were modulated by TMA and water pulses supporting the expected near 1 Å per cycle growth during the second and third ALD cycles. The larger absolute change in the C than the O coverage suggests that the reaction of TMA with O–H groups is more facile than the reaction of water with Al−CH3 moieties, explaining the less than monolayer growth per cycle intrinsic to ALD processes. On the surface prepared using gas phase HF, the fluorides and oxides of all substrate atoms were removed after one complete ALD cycle and a second TMA pulse, which also deposited about two layers of AlOx. Yet, the surface was passivated by the residual F left from the gas phase HF process and by the large increase in C deposited in the first TMA pulse. There is clear evidence for Al–F bonding, and the locations of the Al 2p peaks combined with the large peak widths indicate that the Al atoms deposited in a variety of local bonding environments. The film was not closed off by the first ALD cycle because F and C capped reaction sites, inhibiting further growth of aluminum oxide up to three ALD cycles.