bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of Flow Number in Asphalt Mixtures from Deformation Rate during Secondary State
Authors: Goh Shu Wei , You Zhanping , Wang Hainian , Mills-Beale Julian , Ji Jie
Published: November 2011

Numerous research studies have been conducted on the connection between asphalt material properties and pavement performance. Asphalt mixture performance tests (AMPTs) have been part of these efforts in the past few years. One such test is the flow number test, the output of which is the flow number. Recent studies have found that flow number correlates well with the rutting potential of asphalt pavement. However, the current method used in AMPTs to examine the flow number also was highly sensitive to the variation of testing data (resulting in inaccurate flow number values) and time-consuming, especially when used on stiff asphalt mixtures. The main goal is to determine the flow number with the use of the deformation rate at the secondary state from the result of the flow number test. One hundred twenty-two flow number tests were conducted. A stepwise method was used to overcome variations in results from the flow number test. The flow number was determined with the stepwise method, then compared with the flow deformation rate. A strong correlation between flow number and deformation rate was found. Therefore, the deformation rate can be used to estimate flow number, which significantly reduces testing time. The proposed method also allows the flow number test to be terminated as soon as the permanent strain reaches 1.2%.
Expected Utility Theory, Prospect Theory, and Regret Theory Compared for Prediction of Route Choice Behavior
Authors: de Moraes Ramos Giselle , Daamen Winnie , Hoogendoorn Serge
Published: November 2011

Various decision theories have been used to explain travelers' behavior. This paper presents a comparative analysis from the points of view of theory and application of the expected utility theory, prospect theory, and regret theory. The application was based on an empirical data set on route choice behavior with and without information provision. Results show that despite the widespread use of expected utility theory to model travelers' behavior, the use of prospect theory is quite appropriate and promising, especially when information is provided. The reference point plays an important role in the prediction ability of prospect theory. The greatest prediction ability occurs when the reference point is aligned with the observed behavior and thus reinforces the necessity of establishing appropriate and meaningful values. This study empirically shows the potential of alternatives to expected utility theory to capture travelers' behavior better, as in the case of prospect theory under the proposed model specification, but this is not necessarily true, as demonstrated by the results obtained by use of regret theory.
Parametric Hazard Functions
Authors: Rashidi Taha Hossein , Mohammadian Abolfazl (Kouros)
Published: November 2011

Hazard models are used only moderately in the transportation field compared with their levels of application in other areas, such as medicine, political science, and economics. Many specifications of the hazard models are not well known, whereas the primary application of hazard models is limited to a basic proportional continuous hazard formulation with continuous failure time and Weibull baseline hazard function. Besides the recent advances in the methodology of hazard-based models, the basic proportional hazard formulation remains the proffered hazard-based modeling approach. This paper aims to present some popular specifications of hazard-based models and also discusses some formulations that are less frequently used in practical models. In this study, the Weibull baseline hazard, which is a monotonic function, is replaced by the nonmonotonic log logistic function, and the modified formulation is presented. The log logistic and Weibull formulations are also presented, not only in continuous form but also in discrete hazard formulations for applications in which the failures are observed in discrete time intervals. Finally, all four combinations of discrete and continuous formulations with Weibull and log logistic baselines are discussed with the option of unobserved heterogeneity of type of gamma distribution. The accelerated failure time model, which is an alternative to the proportional hazard models, is discussed. This paper attempts to present a comprehensive overview of the applications of the duration model in the field of transportation.
Repetitiveness of Daily Travel
Authors: Stopher Peter R. , Zhang Yun
Published: November 2011

This paper describes research that explores the use of habitual and repetitive patterns of travel behavior for improving travel demand modeling. The data used in this research came from two Australian panels from which Global Positioning System (GPS) data were collected. The trips recorded by GPS were initially classified into tours. A tour classification that grouped the tours into 12 tour types was then applied, and the number of repetitions of each tour type within the time period of data collection was determined. Having determined how often a particular tour type was repeated over a week or longer, the authors then described tours by certain tour characteristics as the initial means to search for identical patterns of travel from one day to the next. To determine whether a particular tour type was repeated more or less identically on more than one occasion, the tour type repetitions were described by a coefficient of variation for each of tour travel time, tour distance, tour activity time, and total duration (time) of the tour. From this process it was determined that relatively little repetition of tours occurred from one day to the next; this finding raises serious questions about the assumptions of repetitiveness that underlay almost all travel demand models.
The excess burden of osteoarthritis in the province of Ontario, Canada
Authors: Tarride Jean‐Eric , Haq Mahbubul , O'Reilly Daria J. , Bowen James M. , Xie Feng , Dolovich Lisa , Goeree Ron
Published: November 2011

Objective

Little is known about the burden of osteoarthritis (OA) in Canada. This study was undertaken to estimate the excess burden of OA in Ontario, the largest province in Canada.

Methods

The records of Ontarian respondents to the Canadian Community Health Survey (CCHS) who provided consent to data linkage were linked to the Ontario Health Insurance Program physician claims database and the Discharge Abstract Database Inpatient and Day Procedure databases. Patients with OA (n = 1,474) were identified using CCHS 1.1 and the physician claims database. To determine the excess burden of OA, a control group matched by age, sex, and rural/urban status was created, with 3 controls per case (n = 4,422). Sociodemographic and medical characteristics, health‐related quality of life, and 1‐year physician, day (outpatient) procedure, and hospitalization costs were compared between the 2 groups. Regression analyses were performed to identify predictors of medical characteristics, health utility, and cost.

Results

The mean age of the OA patients and the control subjects was 66 years, and 74% of all study subjects were women. Several differences were observed between patients with OA and subjects without OA in terms of socioeconomic and medical characteristics. On a scale of 0–1, the mean utility value associated with OA was 0.68, compared to 0.84 for the control group (P < 0.0001), representing a utility decrement of 0.16. The 1‐year physician, outpatient procedure, and hospitalization costs were significantly higher in the OA group than in the non‐OA group ($2,233 Canadian versus $1,033 Canadian, respectively; P < 0.0001).

Conclusion

These results indicate that the excess burden of OA in Ontario is considerable.
Remote measurement of river morphology via fusion of LiDAR topography and spectrally based bathymetry
Authors: Legleiter Carl J.
Published: November 2011

This study developed and evaluated a hybrid approach to remote measurement of river morphology that combines LiDAR topography with spectrally based bathymetry. Comparison of filtered LiDAR point clouds with surveyed cross‐sections indicated that subtle features on low‐relief floodplains were accurately resolved by LiDAR but that submerged areas could not be detected due to strong absorption of near‐infrared laser pulses by water. The reduced number of returns made the active channel evident in a LiDAR point density map. A second dataset suggested that pulse intensity also could be used to discriminate land from water via a threshold‐based masking procedure. Fusion of LiDAR and optical data required accurate co‐registration of images to the LiDAR, and we developed an object‐oriented procedure for achieving this alignment. Information on flow depths was derived by correlating pixel values with field measurements of depth. Highly turbid conditions dictated a positive relation between green band radiance and flow depth and contributed to under‐prediction of pool depths. Water surface elevations extracted from the LiDAR along the water's edge were used to produce a continuous water surface that preserved along‐channel variations in slope. Subtracting local flow depths from this surface yielded estimates of the bed elevation that were then combined with LiDAR topography for exposed areas to create a composite representation of the riverine terrain. The accuracy of this terrain model was assessed via comparison with detailed field surveys. A map of elevation residuals showed that the greatest errors were associated with underestimation of pool depths and failure to capture cross‐stream differences in water surface elevation. Nevertheless, fusion of LiDAR and passive optical image data provided an efficient means of characterizing river morphology that would not have been possible if either dataset had been used in isolation. Copyright © 2011 John Wiley & Sons, Ltd.
Mapping of homozygous deletions in verified esophageal adenocarcinoma cell lines and xenografts
Authors: Boonstra Jurjen J. , van Marion Ronald , Douben Hannie J. C. W. , Lanchbury Jerry S. , Timms Kirsten M. , Abkevich Victor , Tilanus Hugo W. , de Klein Annelies , Dinjens Winand N. M.
Published: November 2011

Human esophageal adenocarcinoma (EAC) cell lines and xenografts are powerful tools in the search for genetic alterations because these models are composed of pure human cancer cell populations without admixture of normal human cells. In particular detection of homozygous deletions (HDs) is easier using these pure populations of cancer cells. Identification of HDs could potentially lead to the subsequent identification of new tumor suppressor genes (TSGs) involved in esophageal adenocarcinogenesis. Genome wide single nucleotide polymorphism (SNP) arrays were used to identify HDs in 10 verified EAC cell lines and nine EAC xenografts. In total, 61 HDs (range 1–6 per sample) were detected and confirmed by polymerase chain reaction. Besides HDs observed in common fragile genomic regions (n = 26), and gene deserts (n = 8), 27 HDs were located in gene‐containing regions. HDs were noted for known TSGs, including CDKN2A, SMAD4 and CDH3/CDH1. Twenty‐two new chromosomal regions were detected harboring potentially new TSGs involved in EAC carcinogenesis. Two of these regions of homozygous loss, encompassing the ITGAV and RUNX1 gene, were detected in multiple samples indicating a potential role in the carcinogenesis of EAC. To exclude culturing artifacts, these last two deletions were confirmed by fluorescent in situ hybridization in the primary tumors of which the involved cell lines and xenografts were derived. In summary, in this report we describe the identification of HDs in a series of verified EAC cell lines and xenografts. The deletions documented here are a step forward identifying the key genes involved in EAC development. © 2011 Wiley Periodicals, Inc.
A Cognitive Model for Meetings in the Software Development Process
Authors: Misra Sanjay , Akman Ibrahim
Published: November 2011

Meetings are at the heart of the software development process (SDP) and can be of different types. The present article first proposes an abstract cognitive model for meetings, which represents how different types of meetings are affected by cognitive activities at different stages within the SDP. Second, and based on the analysis of meetings at different stages of SDP, it proposes the removal of such meetings from some of the stages within the program by using a cognitive evaluation model for meetings and their replacement, instead, with information and communication technology tools and techniques by means of a cognitive evaluation model. The abstract cognitive model and the evaluation model are validated empirically through experimentation, carried out through a detailed analysis of a target group composed of information technology professionals. © 2011 Wiley Periodicals, Inc.
Effects of rainfall on soil moisture and water movement in a subalpine dark coniferous forest in southwestern China
Authors: Xu Qing , Liu Shirong , Wan Xianchong , Jiang Chunqian , Song Xianfang , Wang Jingxin
Published: November 2011

Water content and movement in soil profile and hydrogen isotope composition (δD) of soil water, rainwater, and groundwater were examined in a subalpine dark coniferous forest in the Wolong National Nature Reserve in Sichuan, China, following rainfall events in 2003–2004. Light rainfall increased water content in the litter and at soil depth of 0–80 cm, but the increased soil water was lost in several days. Heavy rainfall increased soil water content up to 85% at depths of 0–40 cm. Following the light rainfall in early spring, the δD of water from the litter, humus, illuvial, and material layers decreased first and then gradually reached the pre‐rainfall level. In summer, light rainfall reached the litter humus, and illuvial layer, but did not hit the material layer. Heavy rainfall affected δD of water in all layers. The δD of soil interflow slightly fluctuated with rainfall events. The δD of shallow groundwater did not differ significantly among all rainfall events. Light rainfall altered the shape of δD profile curve of water in the upper layer of soil, whereas heavy rainfall greatly affected the shape of δD profile curve of water in all soil layers. Following the heavy rainfall, preferential flow initially occurred through macropores, decayed plant roots, and rocks at different depths of soil profile. With continuing rainfall, the litter and surface soil were nearly saturated or fully saturated, and infiltration became homogeneous and plug‐like. Forest soil water, particularly in deeper soil profile, was slightly affected by rainfall and, thus, can be a source of water supply for regional needs, particularly during dry seasons. Copyright © 2011 John Wiley & Sons, Ltd.
Sublimation over seasonal snowpack at the southeastern edge of a desert in central Eurasia
Authors: Zhou Hong‐Fei , Zheng Xin‐Jun , Zhou Baojia , Dai Qiong , Li Yan
Published: November 2011

The Gurbantonggut Desert, China, is an ideal site for study of sublimation from the snowpack because there are sparse vegetation and simple topography, and the wind speed is not large enough to blow snow into the atmosphere from the snowpack. Daily sublimation was measured by manual snow lysimeters at 8:00, and an automatic weather station was deployed at the top of a stout longitudinal dune chain at the southeastern edge of the desert. It is shown that on a daily scale, there was an extremely significant no‐intercept linear relationship between the measured sublimation and that calculated by the bulk aerodynamic method, although the former was only 83.8% of the latter. It is also demonstrated that −10°C and 2 m/s were the thresholds where the sublimation varied with the air temperature and the wind speed. When these two thresholds were exceeded, the sublimation accelerated. However, the air temperature and the wind speed at 2 m above the ground averaged −17.2°C and 1.3 m/s, respectively, and the percentages of the time when the air temperature was below −10 °C and the wind speed was below 2 m/s were 76.9% and 85.1%, respectively. As a result, the rate of sublimation was quite low most of the time, and the thin snowpack remained in a quasi‐static state until the melt stage started. Copyright © 2011 John Wiley & Sons, Ltd.
High molecular weight polyacrylamides by atom transfer radical polymerization: Enabling advancements in water‐based applications
Authors: Appel Eric A. , del Barrio Jesús , Loh Xian Jun , Dyson Joseph , Scherman Oren A.
Published: November 2011

Through the use of copper (I) chloride (CuCl) and tris(2‐dimethylaminoethyl)amine (Me6‐TREN) as a metal/ligand pair, conditions for the robust, fast, and controlled radical polymerization of high molecular weightN‐hydroxyethylacrylamide (HEAm),N‐isopropylacrylamide (NIPAm),N,N′‐dimethylacrylamide (DMAm), and acrylamide (Am) at ambient temperature are reported. Linear evolution of molecular weight and narrow molecular weight distribution was observed for all monomers with degrees of polymerization ranging from 50 to 5000. Random copolymers of several acrylamide‐based monomers are also reported with excellent control over molecular weight and polydispersity. Characterization of high molecular weight poly (NIPAm) demonstrated large changes in the lower critical solution temperature observed on heating and cooling, and this hysteresis was exploited for the controlled release of doxorubicin from poly(NIPAm) spheres. This study represents the first example of preparation of high molecular weight acrylamide polymers by a metal‐mediated controlled radical polymerization technique. Access to these materials, as well as to NIPAm polymers in particular, opens new doors for interesting applications in a variety of fields including tissue engineering, drug delivery, and controlled solution viscosity. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Copolymerizations of propylene with functionalized long‐chain α‐olefins using group 4 organometallic catalysts and their membrane application
Authors: Zhao Ping , Shpasser Dina , Eisen Moris S.
Published: November 2011

Introduction of functional groups into polyolefins has the potential of broadening their end use. An attractive method for preparing polyolefins containing functional groups is the copolymerization of the olefins with α‐olefins containing a functional group. Copolymerizations of propylene with 10‐undecen‐1‐ol, containing a hydroxyl group protected by either TIBA or TBDMSCl, 11‐chloro‐1‐undecene, 5‐bromopent‐1‐ene and N‐allyl‐2,2,2‐trifluoroacetamide were performed using three organometallic catalysts: the metallocene rac‐Et(Ind)2ZrCl2 and two new benzamidinate catalysts [3‐C5H4NC(NSiCH3)2]2TiCl2 and [(m‐OMe‐C6H4NC(NSiCH3)2]2ZrCl2. 10‐Undecene‐1‐ol protected “in situ” with TIBA and N‐(dec‐9‐enyl)‐2,2,2‐trifluoroacetamide gave copolymers with similar polar monomer incorporation percentages and molecular weights 17%; 28,900 g/mol for the protected 10‐undecene‐1‐ol, and 15%; 27,100 g/mol for N‐(dec‐9‐enyl)‐2,2,2‐trifluoroacetamide. 11‐Chloro‐1‐undecene gave copolymers with up to 22% incorporation for 0.12 M of the comonomer in the reaction feed. The obtained copolymers were characterized by NMR, DSC, and GPC. Membranes were prepared from two copolymers containing the hydroxyl groups (6 and 10%) and one copolymer containing chlorine groups (7%). The membranes prepared could be wetted in contrast to polypropylene membranes which do not contain functional groups. In addition, it was observed that for both type of membranes prepared from the different copolymers containing the hydroxyl groups, the flux was significantly greater than for the membrane prepared from the copolymer containing a chlorine groups. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Managing sensory expectations concerning products and brands: Capitalizing on the potential of sound and shape symbolism
Authors: Spence Charles
Published: November 2011

In this article, the evidence demonstrating the existence of a variety of robust crossmodal correspondences between both sounds (phonetic speech sounds, tones, and other parameters of musical expression) and shapes, and the sensory attributes (specifically the taste, flavor, aroma, and oral‐somatosensory attributes) of various foods and beverages is reviewed. The available research now clearly suggests that marketers can enhance their consumers' product experiences by ensuring that the sound symbolism of the brand name, as well as any shape symbolism of/on the labeling, and even the very shape of the packaging itself, sets up the right (i.e., congruent) product‐related sensory expectations in the mind of the consumer. In this review, the rapidly‐growing literature on the topic of sound and shape symbolism is critically evaluated. Potential caveats, limitations, and problems of interpretation with previous studies are highlighted. The question of whether this approach to sensory marketing should be considered as implicit (or functionally subconscious) is also addressed. Finally, some of the relative strengths and weaknesses of this approach to modulating a consumer's product‐related expectations (relative to various other approaches) are considered.
Mycobacterial Disease in Cats in Great Britain: I. Culture Results, Geographical Distribution and Clinical Presentation of 339 Cases
Authors: Gunn-Moore Daniélle A , McFarland Sarah E , Brewer Jacqueline I , Crawshaw Timothy R , Clifton-Hadley Richard S , Kovalik Marcel , Shaw Darren J
Published: November 2011

This study investigated 339 cases of feline mycobacterial disease from cats with cutaneous lesions or masses found at exploratory laparotomy. Tissue samples were submitted to the Veterinary Laboratories Agency for mycobacterial culture over a 4-year period to December 2008. The study assessed which species of culturable mycobacteria were involved, where the cats lived, and their clinical presentation (physical findings, serum biochemistry, radiography, feline leukaemia virus and feline immunodeficiency virus status). Mycobacterium microti was cultured from 19%, Mycobacterium bovis 15%, Mycobacterium avium 7%, non- M avium non-tuberculous mycobacteria 6%, with no growth in 53% of samples. M microti, M bovis and M avium were found in almost mutually exclusive clusters within Great Britain (GB) (ie, M bovis in South-West England/Wales/Welsh Border, M avium in eastern England and M microti south of London and in South-West Scotland). While differences were seen in the clinical presentation and distribution of lesions caused by the different infections, these were not sufficiently different to be diagnostic. Cats commonly presented with single or multiple cutaneous lesions (74%), which were sometimes ulcerated or discharging, located most frequently on the head (54%). Lymph nodes were usually involved (47%); typically the submandibular nodes. Systemic or pulmonary signs were rarely seen (10–16%). When a cat is suspected of having mycobacteriosis, accurate identification of the species involved helps to determine appropriate action. Our findings show that knowing the cat's geographic location can be helpful, while the nature of the clinical presentation is less useful. Most cases of feline mycobacterial disease in GB are cutaneous.
Thermophysical properties of nitrogen plasmas under thermal equilibrium and non-equilibrium conditions
Authors: Wang Wei Zong , Rong Ming Zhe , Yan J. D. , Murphy A. B. , Spencer Joseph W.
Published: November 2011

Calculated thermophysical properties of nitrogen plasmas in and out of thermal equilibrium are presented. The cut-off of the partition functions due to the lowering of the ionization potential has been taken into account, together with the contributions from different core excited electronic states. The species composition and thermodynamic properties are determined numerically using the Newton–Raphson iterative method, taking into account the corrections due to Coulomb interactions. The transport properties including diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are calculated using the most recent collision interaction potentials by adopting Devoto’s electron and heavy particle decoupling approach, expanded to the third-order approximation (second-order for viscosity) in the framework of Chapman–Enskog method. Results are presented in the pressure range of 0.1 atm–10 atm and in electron temperature range from 300 to 40 000 K, with the ratio of electron temperature to heavy-particle temperature varied from 1 to 20. Results are compared with those from previous works, and the influences of different definitions of the Debye length are discussed.
Dust-acoustic waves in nonuniform dusty plasma in presence of polarization force
Authors: Asaduzzaman M. , Mamun A. A. , Ashrafi K. S.
Published: November 2011

The effects of the dust density nonuniformity and the polarization force on linear propagation of the dust-acoustic waves in a nonuniform dusty plasma (consisting of electrons, ions, and arbitrarily charged dust particles) have been theoretically investigated. It has been shown that the linear dispersion properties of the dust-acoustic (DA) waves have been significantly modified by the dust density nonuniformity, dust polarity, and the polarization force. It is also found here that the phase speed of the DA waves is decreased by the effects of polarization force, and that their amplitude increases with the decrease of equilibrium dust number density. The different situations, which are relevant to different space and laboratory dusty plasmas, have been briefly discussed.
The influence of finite Larmor radius effects on the radial interchange motions of plasma filaments
Authors: Madsen Jens , Garcia Odd E. , Stærk Larsen Jeppe , Naulin Volker , Nielsen Anders H. , Rasmussen Jens Juul
Published: November 2011

The influence of finite Larmor radius (FLR) effects on the perpendicular convection of isolated particle density filaments driven by interchange motions in magnetized plasmas is investigated using a two-moment gyrofluid model. By means of numerical simulations on a two-dimensional, bi-periodic domain perpendicular to the magnetic field, it is demonstrated that the radial velocities of the blob-like filaments are roughly described by the inertial scaling, which prescribes a velocity proportional to the square root of the summed electron and ion pressures times the square root of the blob width. Due to FLR effects, the poloidal up-down symmetry in the particle density field observed in the zero Larmor radius limit is broken. The symmetry breaking implies a poloidal motion of the blobs in the B×∇B direction. At later times, the direction of the poloidal motion is reversed when the blob is decelerated. It is shown that the spatial structure of the blobs depends on the ratio of the ion gyroradius to the initial filament size ρi/σ. Blobs with ρi/σ≳0.2 remain coherent as they move through the scrape-off layer, whereas blobs with ρi/σ≲0.1 form plume-like structures that loose their coherence and eventually become fragmented. After having traveled approximately five times their initial widths, coherent blobs carry ∼2–3 times the particle density of fragmented blobs. It is shown that FLR effects reduce mixing, stretching, and generation of small spatial scales in the particle density field by setting up a sheared flow surrounding the blob.
The nuclear magnetic resonance relaxation data analysis in solids: General R1/R1ρ equations and the model-free approach
Authors: Kurbanov Rauf , Zinkevich Tatjana , Krushelnitsky Alexey
Published: November 2011

The advantage of the solid state NMR for studying molecular dynamics is the capability to study slow motions without limitations: in the liquid state, if orienting media are not used, all anisotropic magnetic interactions are averaged out by fast overall Brownian tumbling of a molecule and thus investigation of slow internal conformational motions (e.g., of proteins) in solution can be conducted using only isotropic interactions. One of the main tools for obtaining amplitudes and correlation times of molecular motions in the μs time scale is measuring relaxation rate R1ρ. Yet, there have been a couple of unresolved problems in the quantitative analysis of the relaxation rates. First, when the resonance offset of the spin-lock pulse is used, the spin-lock field can be oriented under an arbitrary angle in respect to B0. Second, the spin-lock frequency can be comparable or even less than the magic angle spinning rate. Up to now, there have been no equations for R1ρ that would be applicable for any values of the spin-lock frequency, magic angle spinning rate and resonance offset of the spin-lock pulse. In this work such equations were derived for two most important relaxation mechanisms: heteronuclear dipolar coupling and chemical shift anisotropy. The validity of the equations was checked by numerical simulation of the R1ρ experiment using SPINEVOLUTION program. In addition to that, the applicability of the well-known model-free approach to the solid state NMR relaxation data analysis was considered. For the wobbling in a cone at 30º and 90º cone angles and two-site jump models, it has been demonstrated that the auto-correlation functions G0(t), G1(t), G2(t), corresponding to different spherical harmonics, for isotropic samples (powders, polycrystals, etc.) are practically the same regardless of the correlation time of motion. This means that the model-free approach which is widely used in liquids can be equally applied, at least assuming these two motional models, to the analysis of the solid state NMR relaxation data.
Calculation of the exchange coupling constants of copper binuclear systems based on spin-flip constricted variational density functional theory
Authors: Zhekova Hristina R. , Seth Michael , Ziegler Tom
Published: November 2011

We have recently developed a methodology for the calculation of exchange coupling constants J in weakly interacting polynuclear metal clusters. The method is based on unrestricted and restricted second order spin-flip constricted variational density functional theory (SF-CV(2)-DFT) and is here applied to eight binuclear copper systems. Comparison of the SF-CV(2)-DFT results with experiment and with results obtained from other DFT and wave function based methods has been made. Restricted SF-CV(2)-DFT with the BH&HLYP functional yields consistently J values in excellent agreement with experiment. The results acquired from this scheme are comparable in quality to those obtained by accurate multi-reference wave function methodologies such as difference dedicated configuration interaction and the complete active space with second-order perturbation theory.
Computationally efficient self-consistent born approximation treatments of phonon scattering for coupled-mode space non-equilibrium Green’s function
Authors: Afzalian Aryan
Published: November 2011

Efficient schemes for the non-equilibrium Green’s function simulation in the mode space formalism of electron-phonon scattering using the self-consistent Born approximation in nanoscale devices are presented, both using an “exact” and phenomenological Büttiker probe treatment of electron-phonon-scattering. In both cases we have generalized the expressions previously developed for the case of uncoupled mode space to coupled mode space. In the case of the phenomenological Büttiker probe treatment, we have also adapted the expressions used in the exact treatment in order to propose a new microscopic approach of phonon scattering using no analytical or average relaxation time approximations. This allows us to evaluate the accuracy and validity of the Büttiker probe assumption of the existence of a Fermi function in nanoscale devices. Our findings are that if the trends of the exact scattering are approximately reproduced by the Büttiker probe method, it seems to overestimate the on-current for a large range of devices with a channel length of a few tens of nanometers and a drain voltage higher than 100 mV.
Note: Fabrication of a simple versatile micro-positioning setup for automated soft lithography
Authors: Hautefeuille M. , Lopez Cortes J. G. , Ortega Alfaro M. C. , Carreon Castro M. P. , Velazquez V.
Published: November 2011

In this note, we report the simple development of a homemade versatile device that allows micrometric vertical micro-positioning for computer-controlled dip-coating thin film deposition and micro-contact printing capabilities. Using mostly recycled parts, the resulting low-cost setup offers great precision, ease of use, and portability while complying with common soft lithography technique's specifications. It results in an excellent benchtop alternative to more expensive commercial solutions or more complex custom soft lithography devices, especially for organic electronics and quantum optics applications.
Oxygen rich p-type ZnO thin films using wet chemical route with enhanced carrier concentration by temperature-dependent tuning of acceptor defects
Authors: Ilyas Usman , Rawat R. S. , Tan T. L. , Lee P. , Chen R. , Sun H. D. , Fengji Li , Zhang Sam
Published: November 2011

This paper reports the temperature-dependent tailoring of acceptor defects in oxygen rich ZnO thin films, for enhanced p-type conductivity. The oxygen rich p-type ZnO thin films were successfully grown by pulsed laser deposition on silicon substrate at different postdeposition annealing temperatures (500–800 °C). The oxygen rich ZnO powder was synthesized by wet chemical method using zinc acetate dihydrate [Zn(CH3COO)2·2H2O] and potassium hydroxide (KOH) as precursors. The powder was then compressed and sintered to make pellets for pulsed laser deposition system. The x-ray diffraction analysis exhibits an improved crystallinity in thin films annealed at elevated temperatures with a temperature-dependent variation in lattice constants. An analysis of Auger Zn L3M4,5M4,5 peak reveals a consistent decrease in interstitial zinc (Zni) exhibiting its temperature-dependent reversion to zinc lattice sites. Room temperature photoluminescence of the p-type ZnO shows a dominant deep level emission peak at ∼3.12 eV related to oxygen interstitials (acceptors). The relative concentration of oxygen interstitials (Oi) increases with increase in annealing temperature, resulting in enhanced hole carrier concentration. The maximum hole carrier concentration of 6.8 × 1014 cm−3 (indicating p-type conductivity) was estimated using Hall probe measurements for the thin film sample annealed at 700 °C.
Amplification of spin waves in yttrium iron garnet films through the spin Hall effect
Authors: Padrón-Hernández E. , Azevedo A. , Rezende S. M.
Published: November 2011

We demonstrate that spin waves propagating in a film of yttrium iron garnet (YIG) can be amplified by a dc current in an adjacent Pt layer by means of the spin Hall effect. The experiments are done at room temperature using pulsed currents to avoid sample heating. Amplification occurs only for surface like modes propagating in a direction perpendicular to the applied in-plane field. The results are interpreted with a model for spin-wave propagation in a YIG film with magnetic losses and subject to a spin-transfer torque due to spin currents created by the spin Hall effect in the Pt layer.
Photodiode with nanocrystalline Si/amorphous Si absorber bilayer
Authors: Vygranenko Y. , Sazonov A. , Fernandes M. , Vieira M.
Published: November 2011

This letter reports a near-ultraviolet/visible/near-infrared n+-n-i-δi-p photodiode with an absorber comprising a nanocrystalline silicon n layer and a hydrogenated amorphous silicon i layer. Device modeling reveals that the dominant source of reverse dark current is deep defect states in the n layer, and its magnitude is controlled by the i layer thickness. The photodiode with the 900/400 nm thick n-i layers exhibits a reverse dark current density of 3nA/cm2 at −1 V. Donor concentration and diffusion length of holes in the n layer are estimated from the capacitance-voltage characteristics and from the bias dependence of long-wavelength response, respectively.
Polarons in low temperature phase of (NH4)3FeF6
Authors: Filipič C. , Bobnar V. , Tavčar G. , Žemva B. , Levstik A.
Published: November 2011

The frequency and temperature dependence of the dielectric constant and the ac electrical conductivity in (NH4)3FeF6 was investigated. The temperature dependence of the dielectric constant reveals the phase transition from tetragonal to cubic phase at 270 K. At temperatures below 225 K, the ac conductivity and dielectric constant follow the universal dielectric response (UDR), being typical for hopping or tunneling of localized charge carriers. A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that below 225 K this mechanism governs the charge transport in this fluoride system.
Excited states of ribosome translocation revealed through integrative molecular modeling
Authors: Whitford Paul C. , Ahmed Aqeel , Yu Yanan , Hennelly Scott P. , Tama Florence , Spahn Christian M. T. , Onuchic José N. , Sanbonmatsu Karissa Y.
Published: November 2011

The dynamic nature of biomolecules leads to significant challenges when characterizing the structural properties associated with function. While X-ray crystallography and imaging techniques (such as cryo-electron microscopy) can reveal the structural details of stable molecular complexes, strategies must be developed to characterize configurations that exhibit only marginal stability (such as intermediates) or configurations that do not correspond to minima on the energy landscape (such as transition-state ensembles). Here, we present a methodology (MDfit) that utilizes molecular dynamics simulations to generate configurations of excited states that are consistent with available biophysical and biochemical measurements. To demonstrate the approach, we present a sequence of configurations that are suggested to be associated with transfer RNA (tRNA) movement through the ribosome (translocation). The models were constructed by combining information from X-ray crystallography, cryo-electron microscopy, and biochemical data. These models provide a structural framework for translocation that may be further investigated experimentally and theoretically to determine the precise energetic character of each configuration and the transition dynamics between them.
Protein kinase Ypk1 phosphorylates regulatory proteins Orm1 and Orm2 to control sphingolipid homeostasis in
Saccharomyces cerevisiae
Authors: Roelants Françoise M. , Breslow David K. , Muir Alexander , Weissman Jonathan S. , Thorner Jeremy
Published: November 2011

The Orm family proteins are conserved integral membrane proteins of the endoplasmic reticulum that are key homeostatic regulators of sphingolipid biosynthesis. Orm proteins bind to and inhibit serine:palmitoyl-coenzyme A transferase, the first enzyme in sphingolipid biosynthesis. In
Saccharomyces cerevisiae
, Orm1 and Orm2 are inactivated by phosphorylation in response to compromised sphingolipid synthesis (e.g., upon addition of inhibitor myriocin), thereby restoring sphingolipid production. We show here that protein kinase Ypk1, one of an essential pair of protein kinases, is responsible for this regulatory modification. Myriocin-induced hyperphosphorylation of Orm1 and Orm2 does not occur in
ypk1∆
cells, and immunopurified Ypk1 phosphorylates Orm1 and Orm2 robustly in vitro exclusively on three residues that are known myriocin-induced sites. Furthermore, the temperature-sensitive growth of

ypk1
ts

ypk2∆
cells is substantially ameliorated by deletion of
ORM
genes, confirming that a primary physiological role of Ypk1-mediated phosphorylation is to negatively regulate Orm function. Ypk1 immunoprecipitated from myriocin-treated cells displays a higher specific activity for Orm phosphorylation than Ypk1 from untreated cells. To identify the mechanism underlying Ypk1 activation, we systematically tested several candidate factors and found that the target of rapamycin complex 2 (TORC2) kinase plays a key role. In agreement with prior evidence that a TORC2-dependent site in Ypk1(T662) is necessary for cells to exhibit a wild-type level of myriocin resistance, a Ypk1(T662A) mutant displays only weak Orm phosphorylation in vivo and only weak activation in vitro in response to sphingolipid depletion. Additionally, sphingolipid depletion increases phosphorylation of Ypk1 at T662. Thus, Ypk1 is both a sensor and effector of sphingolipid level, and reduction in sphingolipids stimulates Ypk1, at least in part, via TORC2-dependent phosphorylation.
Arcanobacterium canis sp. nov., isolated from otitis externa of a dog, and emended description of the genus

Arcanobacterium

Collins et al. 1983 emend. Yassin et al. 2011
Authors: Hijazin Muaz , Prenger-Berninghoff Ellen , Sammra Osama , Alber Jörg , Lämmler Christoph , Kämpfer Peter , Glaeser Stefanie P. , Busse Hans-Jürgen , Hassan Abdulwahed Ahmed , Abdulmawjood Amir , Zschöck Michael
Published: November 2011

A polyphasic taxonomic study was performed on an unidentified

Arcanobacterium

-like Gram-stain-positive bacterium isolated from otitis externa of a dog. Comparative 16S rRNA gene sequencing showed that the bacterium belonged to the genus

Arcanobacterium

and was most closely related to the type strains of

Arcanobacterium haemolyticum

(97.2 %),

Arcanobacterium hippocoleae

(96.5 %) and

Arcanobacterium phocae

(96.4 %). The presence of the major menaquinone MK-9(H4) supported the affiliation of this strain to the genus

Arcanobacterium

. The polar lipid profile contained the major lipids phosphatidylcholine, diphosphatidylglycerol, phosphatidylinositol mannoside and an unidentified phospholipid (PL2). Major fatty acids were C14 : 0, C16 : 0, C18 : 0, C18 : 1ω9c and C18 : 2ω6,9c/anteiso-C18 : 0 (detected as a summed feature). C10 : 0 and C12 : 0 were present in minor amounts. The results of physiological and biochemical testing clearly distinguished the unknown bacterium from other species of the genus

Arcanobacterium

. Based on these tests, it is proposed that the unknown bacterium should be classified in the novel species Arcanobacterium canis sp. nov. The type strain of Arcanobacterium canis is P6775T ( = CCM 7958T  = CCUG 61573T  = CIP 110339T). An emended description of the genus

Arcanobacterium

is also provided.
Celebrity advertising in the case of negative associations: discourse analysis of weblogs
Authors: Akturan Ulun
Published: November 2011

Purpose

The purpose of this paper is to examine celebrity advertising in the case of negative associations.

Design/methodology/approach

In total, 451 posts were captured permanently from randomly selected weblogs, and analyzed by discourse analysis. The basic emerging themes therein have been isolated and interpreted, and a model of celebrity endorsement in the case of negative information has been developed.

Findings

When a celebrity becomes involved in an undesirable event, the consumers' perceptions of the celebrity may or may not change. This study argues that this situation is influenced by “the level of negativity”, “the level of blameworthiness”, “admiration” and the “message content”. In addition, it was found that the admiration affects the perceived image of the celebrity and it is also affected by “the level of negativity” and “the level of blameworthiness”. Furthermore, the message given is directly associated with the “negativity”, “blameworthiness”, “perception of the celebrity”, and “the perception of the brand”.

Research limitations/implications

The present study examined only one case of celebrity advertising.

Practical implications

The expectations and attitudes of the identified segments should be taken into consideration when firms develop marketing programs.

Originality/value

This study, unlike others, analyzes the case of the continuance of the endorsement relationship between the company and the negatively publicized celebrity.
Protecting from brand burn during times of crisis
Authors: Stephens Balakrishnan Melodena
Published: November 2011

Purpose

Managing brands during crisis (in the context of terrorism) does not have much historical research and the studies that exist focus on communication. Terrorism is more frequent; not easily prevented; and rarely a top management priority for risk management. The purpose of this paper is to use exiting theory on brand components and architecture to prevent brand burn. Brand burn is defined as the accidental negative impact formed on a brand due to a crisis outside the control of an organization, which may not be perceived as directly related to the organization's product or management.

Design/methodology/approach

Crises are characterized by an overload of information. The exploratory study uses a case study methodology to get insights on how to manage a brand through a crisis. To validate findings, triangulation using independent reviewers, theory and secondary reports is used.

Findings

First, a conceptual framework to manage brand burn is presented. Second, from the practitioner's point of view, the paper provides a checklist that gives strategic tips for preparing for and managing brand crisis. The findings show that both brand components and brand architecture can be used to manage brands through crisis.

Research limitations/implications

The findings contribute to theory by adding to the evolving literature on brand architecture, brand components and crisis management. Key challenges were organizing and prioritizing the vast amount of data from secondary sources, including social media sites; time was an issue as memories fade; and another limitation was getting official confirmation since perceptions play a key role.

Originality/value

This is the first study looking at a terrorist crisis from a brand management point of view. This paper contributes to theory by adding to the research in brand architecture and brand components and crisis management. Future studies can look at the model robustness in other crisis situations and the impact of managing social media.
Investigation of two dimensional flow past multi element airfoils for general transport aircraft
Authors: Singh Manish , Dhanalakshmi Kumar , Mathur Jaideep
Published: November 2011

Purpose

Air connectivity network is an important part of the overall connectivity network of any country. This becomes even more crucial for the interior regions, which have no access to sea routes and have inadequate road and rail connectivity. In India there is uniform distribution of airports throughout the country but only a few of them are currently used because of poor infrastructure availability at these airports. Any aircraft operating from these airports, having minimal infrastructure, need to have efficient high‐lift systems for short takeoff and landing ability as one of the key requirements. The purpose of this paper is look at the performance of a new high‐lift airfoil configuration for application to a general transport aircraft.

Design/methodology/approach

The present study deals with two‐dimensional analyses of a high‐lift system for general transport aircraft. The JUMBO2D, a multi‐block structured viscous code has been used to make preliminary analysis of the proposed high‐lift system. The configuration consists of three elements, namely, the main airfoil with nose droop, a vane and a flap.

Findings

In the present work the code has been revalidated by computing for NLF (1) 0416 airfoil (clean) and NACA 1410 airfoil with double‐slotted flap. The computed results compare very well with the experimental data. The proposed high‐lift configuration of general transport aircraft has then been analyzed in detail for both takeoff and landing conditions with and without nose droop. The effect of gap between main element and vane on the aerodynamic performance has also been investigated.

Originality/value

This computational study looks at the performance of a new high‐lift airfoil configuration for application to a general transport aircraft.