bluuebunny/crossref_metadata_2025 huggingface dataset:
Scaling, asymmetry and a Fokker–Planck model of the fast and slow solar wind as seen by WIND
Authors: Hnat Bogdan , Chapman Sandra C. , Rowlands George
Published: April 2004

The solar wind plasma is a natural laboratory for studies of plasma turbulence. Long, evenly sampled satellite data sets are natural candidates for statistical studies and these are often performed in the context of magnetohydrodynamic (MHD) turbulence. In this paper, scaling properties of solar wind bulk plasma parameters are discussed. Low order probability density function (PDF) asymmetry analysis is applied to data that combines slow and fast solar wind. Results are compared to those obtained using a PDF rescaling technique. A break in scaling, identified by the rescaling method, is confirmed to occur at a temporal scale of ∼26 hours. Low asymmetry levels of the fluctuations PDF are identified for the quantities that also exhibit self-similar statistics. A generalized structure function analysis is then applied to the kinetic energy density obtained from slow and fast solar wind streams. The applicability of a Fokker–Planck model for slow and fast wind ρv2 fluctuations is investigated.
Comment on “Dynamics of zonal flow saturation in strong collisionless drift wave turbulence” [Phys. Plasmas 9, 4530 (2002)]
Authors: Krommes J. A.
Published: April 2004

A conceptual error is identified in the recent derivation by Kim and Diamond [Phys. Plasmas 9, 4530 (2002)] of the nonlinear growth rate γq of so-called generalized Kelvin–Helmholtz modes in the cold-ion limit. When corrected, the result agrees with the formula published earlier by Krommes and Kim [Phys. Rev. E 62, 8508 (2000)] except for subtleties about the determination of the relevant triad interaction time.
Investigation of transport in the DIII-D edge pedestal
Authors: Stacey W. M.
Published: April 2004

A comparison of various heat conduction theories with data from several DIII-D [Luxon, Nucl. Fusion 42, 614 (2002)] shots indicates: (1) that neoclassical theory is in somewhat better agreement with experiment than is ion temperature gradient mode theory for the ion thermal conductivity in the edge pedestal, although both are in reasonable agreement with experiment for most discharges; and (2) that electron temperature gradient theory (k⊥cs⩽ωpe) is in much better agreement with experiment than is electron drift wave theory (k⊥cs⩽Ωi) for the electron thermal conductivity. New theoretical expressions derived from momentum balance are presented for: (1) a “diffusive-pinch” particle flux, (2) an experimental determination of the momentum transfer frequency, and (3) the density gradient scale length. Neither atomic physics nor convection can account for the measured momentum transfer frequencies, but neoclassical gyroviscosity predictions are of the correct magnitude.
Fluctuation theorem for nonequilibrium reactions
Authors: Gaspard Pierre
Published: April 2004

A fluctuation theorem is derived for stochastic nonequilibrium reactions ruled by the chemical master equation. The theorem is expressed in terms of the generating and large-deviation functions characterizing the fluctuations of a quantity which measures the loss of detailed balance out of thermodynamic equilibrium. The relationship to entropy production is established and discussed. The fluctuation theorem is verified in the Schlögl model of far-from-equilibrium bistability.
Accurate intermolecular ground state potential of the Ne–N2 van der Waals complex
Authors: Munteanu Cristian R. , Cacheiro Javier López , Fernández Berta
Published: April 2004

Ab initio ground state potential energy surfaces are obtained from interaction energies calculated with the coupled cluster singles and doubles model including connected triples corrections [CCSD(T)] and the aug-cc-pVXZ (X=5,Q,T,D) basis sets augmented with two different sets of midbond functions (denoted 33221 and 33211). The aug-cc-pV5Z-33221 surface is characterized by a T-shaped 49.5 cm−1 minimum at Re=3.38 Å and a linear saddle point at 3.95 Å with De=36.6 cm−1. These results agree well with the values provided by the accurate semiempirical potentials available. The rovibronic spectroscopic properties are determined and compared to the available experimental data and previous theoretical results. We study the basis set convergence of the intermolecular potentials and the rotational frequencies. The aug-cc-pVTZ basis sets provide reasonable binding parameters, but seem not to be converged enough for the evaluation of the microwave spectra. The aug-cc-pVQZ basis sets considerably improve the triple zeta results. The differences between the results obtained with the aug-cc-pVTZ-33221 basis set surface and those with the aug-cc-pVQZ-33221 are smaller than those of the corresponding bases with the set of 33211 midbond functions. The aug-cc-pVQZ surfaces are close to the aug-cc-pV5Z, that are expected to be close to convergence. With our best surfaces the errors in the frequencies with respect to the accurate experimental results go down to 0.6%.
Dynamical behavior of one-dimensional water molecule chains in zeolites: Nanosecond time-scale molecular dynamics simulations of bikitaite
Authors: Demontis Pierfranco , Stara Giovanna , Suffritti Giuseppe B.
Published: April 2004

Nanosecond scale molecular dynamics simulations of the behavior of the one-dimensional water molecule chains adsorbed in the parallel nanochannels of bikitaite, a rare lithium containing zeolite, were performed at different temperatures and for the fully and partially hydrated material. New empirical potential functions have been developed for representing lithium–water interactions. The structure and the vibrational spectrum of bikitaite were in agreement both with experimental data and Car–Parrinello molecular dynamics results. Classical molecular dynamics simulations were extended to the nanosecond time scale in order to study the flip motion of water molecules around the hydrogen bonds connecting adjacent molecules in the chains, which has been observed by NMR experiments, and the dehydration mechanism at high temperature. Computed relaxation times of the flip motion follow the Arrhenius behavior found experimentally, but the activation energy of the simulated system is slightly underestimated. Based on the results of the simulations, it may be suggested that the dehydration proceeds by a defect-driven stepwise diffusion. The diffusive mechanism appears as a single-file motion: the molecules never pass one another, even at temperatures as high as about 1000 K, nor can they switch between different channels. However, the mean square displacement (MSD) of the molecules, computed with respect to the center of mass of the simulated system, shows an irregular trend from which the single-file diffusion cannot be clearly evidenced. If the MSDs are evaluated with respect to the center of mass of the molecules hosted in each channel, the expected dependence on the square root of time finally appears.
Infrared-induced conformational isomerization and vibrational relaxation dynamics in melatonin and 5-methoxy-N-acetyl tryptophan methyl amide
Authors: Dian Brian C. , Florio Gina M. , Clarkson Jasper R. , Longarte Asier , Zwier Timothy S.
Published: April 2004

The conformational isomerization dynamics of melatonin and 5-methoxy N-acetyltryptophan methyl amide (5-methoxy NATMA) have been studied using the methods of IR-UV hole-filling spectroscopy and IR-induced population transfer spectroscopy. Using these techniques, single conformers of melatonin were excited via a well-defined NH stretch fundamental with an IR pump laser. This excess energy was used to drive conformational isomerization. By carrying out the infrared excitation early in a supersonic expansion, the excited molecules were re-cooled into their zero-point levels, partially re-filling the hole created in the ground state population of the excited conformer, and creating gains in population of the other conformers. These changes in population were detected using laser-induced fluorescence downstream in the expansion via an UV probe laser. The isomerization quantum yields for melatonin show some conformation specificity but no hint of vibrational mode specificity. In 5-methoxy NATMA, no isomerization was observed out of the single conformational well populated in the expansion in the absence of the infrared excitation. In order to study the dependence of the isomerization on the cooling rate, the experimental arrangement was modified so that faster cooling conditions could be studied. In this arrangement, the pump and probe lasers were overlapped in space in the high density region of the expansion, and the time dependence of the zero-point level populations of the conformers was probed following selective excitation of a single conformation. The analysis needed to extract isomerization quantum yields from the timing scans was developed and applied to the melatonin timing scans. Comparison between the frequency and time domain isomerization quantum yields under identical experimental conditions produced similar results. Under fast cooling conditions, the product quantum yields were shifted from their values under standard conditions. The results for melatonin are compared with those for N-acetyl tryptophan methyl amide.
S
(
1
S)
production following electron impact on thiophosgene (Cl2CS)
Authors: Kedzierski W. , Borbely J. , Mutus J. , Amlin S. , McConkey J. W.
Published: April 2004

A special xenon matrix detector has been used to study the production of S(1S) following controlled electron impact on thiophosgene (Cl2CS) targets over an electron energy range from threshold to 400 eV. Time-of-flight spectroscopy has been used to measure S(1S) fragment kinetic energies. Fragments with energies in excess of 1 eV have been observed. The absolute cross section for S(1S) production reaches a maximum of [1.05±0.35]×10−18 cm2 at approximately 125 eV impact energy. Two different fragmentation processes, involving triplet and singlet excited states of the parent Cl2CS molecule, have been identified.
Efficient dehalogenation of polyhalomethanes and production of strong acids in aqueous environments: Water-catalyzed O–H-insertion and HI-elimination reactions of isodiiodomethane (CH2I–I) with water
Authors: Kwok Wai Ming , Zhao Cunyuan , Guan Xiangguo , Li Yun-Liang , Du Yong , Phillips David Lee
Published: April 2004

A combined experimental and theoretical study of the ultraviolet photolysis of CH2I2 in water is reported. Ultraviolet photolysis of low concentrations of CH2I2 in water was experimentally observed to lead to almost complete conversion into CH2(OH)2 and 2HI products. Picosecond time-resolved resonance Raman spectroscopy experiments in mixed water/acetonitrile solvents (25%–75% water) showed that appreciable amounts of isodiiodomethane (CH2I–I) were formed within several picoseconds and the decay of the CH2I–I species became substantially shorter with increasing water concentration, suggesting that CH2I–I may be reacting with water. Ab initio calculations demonstrate the CH2I–I species is able to react readily with water via a water-catalyzed O–H-insertion and HI-elimination reaction followed by its CH2I(OH) product undergoing a further water-catalyzed HI-elimination reaction to make a H2C=O product. These HI-elimination reactions produce the two HI leaving groups observed experimentally and the H2C=O product further reacts with water to produce the other final CH2(OH)2 product observed in the photochemistry experiments. These results suggest that CH2I–I is the species that reacts with water to produce the CH2(OH)2 and 2HI products seen in the photochemistry experiments. The present study demonstrates that ultraviolet photolysis of CH2I2 at low concentration leads to efficient dehalogenation and release of multiple strong acid (HI) leaving groups. Some possible ramifications for the decomposition of polyhalomethanes and halomethanols in aqueous environments as well as the photochemistry of polyhalomethanes in the natural environment are briefly discussed.
Theory of counter-ion condensation on flexible polyelectrolytes: Adsorption mechanism
Authors: Muthukumar M.
Published: April 2004

A new model is presented for counterion distribution around flexible polyelectrolytes by considering (i) free energy of the polyelectrolyte chain, (ii) translational entropy of adsorbed counterions, (iii) adsorption energy, (iv) translational entropy of unadsorbed counterions, (v) fluctuations of dissociated ions, and (vi) correlation among ion-pairs formed by adsorbed counterions on the polymer. The effective charge and size of the polymer are calculated self-consistently. The degree of ionization f of the polymer decreases continuously with 1/εT (ε and T are the dielectric constant of the solvent and temperature, respectively), depending sensitively on local dielectric heterogeneity. Further, f decreases with an increase in salt concentration, monomer concentration, or chain flexibility. The polymer size, accompanying the changes in f, depends nonmonotonically on 1/εT. The predictions of the model are consistent with all trends observed previously in simulations and are distinctly different from the Manning argument for rodlike chains.
Features of the local structure of fine-grained HTSC YBa2Cu2.985 57Fe0.015Oy
Authors: Vishnev A. A. , Makarov E. F. , Mamsurova L. G. , Pigalskiy K. S. , Permyakov Yu. V.
Published: April 2004

Polycrystalline high-Tc superconductors (HTSCs) with the composition YBa2Cu2.985 57Fe0.015Oy (y≈6.92, Tc=91–91.5 K) with micron and submicron grain sizes are investigated by the method of gamma resonance (Mössbauer) spectroscopy at temperatures of 293, 91, and 78 K. A correlation is found between the changes of the intensities of the components of the Mössbauer spectra and the mean grain sizes 〈D〉. It is shown that the observed changes in the spectra are caused by an interplane redistribution of oxygen wherein the oxygen content δ in the (CuOδ) planes increases and the lattice parameter c decreases. This effect is greater for smaller mean grain sizes 〈D〉. It is concluded that the observed changes in the anion subsystem of the fine-grained HTSCs as compared to bulk equilibrium samples of YBa2Cu3O6+δ are mainly due to a partial interchange of the Y3+ and Ba2+ cations in them. This interchange may be a result of the nonequilibrium synthesis conditions that must be used to produce HTSCs with micron and submicron grain sizes.
Structural and high-frequency (0–110 MHz) resistive characteristics of MgB2 in the temperature range 5–300 K
Authors: Dmitriev V. M. , Prentslau N. N. , Baumer V. N. , Galtsov N. N. , Ishchenko L. A. , Prokhvatilov A. L. , Strzhemechny M. A. , Terekhov A. V. , Bykov A. I. , Liashenko V. I. , Paderno Yu. B. , Paderno V. N.
Published: April 2004

The structure and resistivity of polycrystalline MgB2 and its impedance at frequencies of 9–110 MHz are determined in the temperature range 5–300 K. It is shown that the lattice type and symmetry of the superconducting phase of MgB2 remain unchanged over this temperature range. At the superconducting transition temperature Tc=39.5 K a structural instability is observed which is accompanied by an overshoot of the measured lattice parameters. It is concluded that the strain of the crystals upon a change in temperature is of a substantially anisotropic character. Measurements of the temperature and frequency dependence of the surface resistance Rs(T,f ) in the superconducting state reveal a transition from the Pippard nonlocal limit at T≪Tc to the London local limit near Tc. At T/Tc<0.76 the value of Rs(T) is well described by an exponential dependence exp(−Δ(T)/kT) in accordance with the BCS theory.
Structural imperfection, phase transitions, and the properties of magnetoresistive ceramic and films of La0.66Mn1.23V0.11(c)O2.842−V0.16(a)
Authors: Paschenko V. P. , Shemyakov A. A. , Pashechenko A. V. , Tsymbal L. T. , Kakazei G. K. , Dyakonov V. P. , Szymczak H. , Santos J. A. M. , Sousa J. B.
Published: April 2004

It is established by x-ray, resistive, NMR, and magnetoresistive studies of ceramic and thin-film laser perovskites La0.7Mn1.3O3 with “excess” manganese that the real structure of these compounds contains heterovalent manganese ions and cationic and anionic vacancies and clusters, the magnetism and resistivity of the latter being manifested near 42 K. The broad, asymmetric 55Mn and 139La NMR spectra of the ceramics attest to the presence of high-frequency electron–hole exchange between the heterovalent manganese ions and to a high degree of imperfection and mesoscopic inhomogeneity of nonstoichiometric lanthanum manganite perovskites. The differences of the metal–semiconductor phase transition temperatures and activation energy of the ceramics and films is explained by the different oxygen nonstoichiometry, structural imperfection, and, accordingly, densities of charge carriers and excitons. The low-field magnetoresistive effect of the ceramic is explained by tunneling at grain boundaries. It is conjectured that the decrease in resistance in magnetic field is due to an increase in charge carrier density due to weakening of the electron–hole interaction in excitons. An anomaly of the resistance and magnetoresistive effect observed near 42 K is explained by the presence of clusters.
Thermodynamic properties of the Cu–Au system using a face-centered-cubic lattice model with a renormalized potential
Authors: Sahara Ryoji , Ichikawa Hiroshi , Mizuseki Hiroshi , Ohno Kaoru , Kubo Hiroshi , Kawazoe Yoshiyuki
Published: April 2004

A Monte Carlo simulation is carried out to study thermodynamic properties of Cu–Au alloys using a face-centered-cubic (fcc) lattice-gas model. To obtain quantitatively accurate results, a Finnis–Sinclair-type potential, which has been widely used for molecular dynamics (MD) simulations, is employed. To overcome some shortcomings of lattice-gas models such as neglecting vibrational entropy, the potential is mapped onto the fcc lattice using the renormalization technique. The renormalized potential gives an improved Cu–Au phase diagram compared to the original MD potential applied directly on the lattice.
Boundary friction on molecular lubricants: rolling mode?
Authors: Loktev V. M. , Pogorelov Yu. G.
Published: April 2004

A theoretical model is proposed for low-temperature friction between two smooth, rigid solid surfaces separated by lubricant molecules, admitting their deformations and rotations. The appearance of different modes of energy dissipation (by “rocking” or “rolling” of lubricants) at slow relative displacement of the surfaces is shown to be accompanied by stick-and-slip features and reveals a nonmonotonic (mean) friction force versus external load.
Complexation of semiflexible chains with oppositely charged cylinder
Authors: Cherstvy Andrey G. , Winkler Roland G.
Published: April 2004

We study the complexation of long thin semiflexible polymer chains with an oppositely charged cylinder. Starting from the linear Poisson–Boltzmann equation, we calculate the electrostatic potential and the energy of such a charge distribution. We find that sufficiently flexible chains prefer to wrap around the cylinder in a helical manner, when their charge density is smaller than that of the cylinder. The optimal value of the helical pitch is found by minimization of the sum of electrostatic and bending energies. The dependence of the pitch on the number of chains, their rigidity, and salt concentration in solution is analyzed. We discuss our results in the light of recent experiments on DNA complexation with cylindrical dendronized polymers.
Electric field gradients from shifted-nucleus calculations: An alternative to the point charge nuclear quadrupole moment model
Authors: Kellö Vladimir , Sadlej Andrzej J.
Published: April 2004

The electric field gradient operator is modeled in terms of potentials due to displaced nuclei. In comparison with the earlier point charge nuclear quadrupole moment model, the present method needs only one parameter to be determined. The numerical stability of the proposed method is illustrated. The shifted-nucleus model is advocated in quasirelativistic calculations as an easy way to avoid the explicit change of picture for the field gradient operator.
Reappraisal of four different approaches for finding the mean reaction time in the multi-trap variant of the Adam–Delbrück problem
Authors: Martins Jorge , Melo Eurico , Naqvi K. Razi
Published: April 2004

Adam and Delbrück argued that the dimensionality of the diffusion space determines the average lifetime of a diffusing particle confined to a region with a central trap. Doubts have often been aired as to whether their calculation is relevant to real biological systems, where the number of traps is usually much larger than unity; or whether the rate enhancement is merely a manifestation of an increase in the concentration of the traps; or whether the diverse multi-trap versions of their expression for the mean lifetime in two dimensions are trustworthy. These issues are addressed, and the long-standing problem of finding the low-density limit of trapping time in two dimensions solved, by examining previous treatments of the problem, and by carrying out simulations of two-dimensional systems in which the particles undergo a Pearsonian random walk, and the traps are distributed randomly or on a square lattice. The mean lifetimes are found to be different in the two situations, and it is concluded that the neglect of this aspect lies at the root of the conflict between some of the existing expressions for the mean lifetime. Relations expressing the mean lifetime as a function of the concentration of the traps are presented together with a discussion of their applicability.
Effects of cooking practices (boiling and frying) on the protein and amino acids contents of four selected fishes
Authors: Ismail Amin , Hainida Khairul Ikram Emmy
Published: April 2004

This study was aimed to estimate and compare the contents of protein and amino acids in raw, boiled and fried fishes of Indian mackerel “kembong” (Rastrelliger kanagurta), sardine (Sardina pilchardus), red tilapia (Oreochromis mossambicusx) and black tilapia (Oreochromis mossambicus). Protein contents of raw mackerel, sardine, red and black tilapia were 8.1±0.0, 8.4±0.1, 9.6±0.4 and 9.0±0.0 percent, respectively. In a boiled fish, the protein contents were 7.9±0.1, 7.7±0.0, 7.5±0.1 and 8.9±0.1 percent, respectively, and for a fried fish the values were 8.6±0.5, 8.9±0.1, 9.1±0.2 and 8.4±0.0 percent, respectively. It was found that there was a significant difference (p<0.01) in the protein content of the raw fish compared to the heat‐treated ones for all the fishes. The study detected 17 components of essential amino acids (lysine, histidine, threonine, valine, methionine, leucine, isoleucine and phenylalanine) and non‐essential amino acids (arginine, aspartic acid, serine, glutamic acid, proline, glycine, alanine, cystein and tyrosine) in all the fishes. There was no significant difference in amino acids content among the boiled and fried fishes. In conclusion, heat treatment for five minutes in boiling water (100°C) and frying for three minutes in palm oil (160°C) did not alter the quality of protein in all the fishes studied.
Hypoglycemia and faecal minerals in rats fed phytate
Authors: Dilworth Lowell L. , Omoruyi Felix O. , Simon Oswald , Morrison Errol Y. , Asemota Helen N.
Published: April 2004

In this study, phytic acid was extracted from Jamaican sweet potato, which has been reported to contain a high phytic acid to zinc ratio and fed to Wistar rats for three weeks. Animals were then sacrificed and blood glucose, intestinal amylase activity and faecal minerals were determined. Blood glucose levels in all the groups fed phytic acid extract from sweet potato or commercial phytic acid were reduced compared to their controls. This lowering was more pronounced in the groups fed phytic acid extract from sweet potato or commercial phytic acid plus zinc supplement. Faecal zinc was significantly higher in the groups fed phytic acid extract from sweet potato compared to the controls in weeks 1 and 2. Supplementation of the diets with phytic acid extract from sweet potato or commercial phytic acid resulted in an increase in the faecal output of iron except for the group that was fed commercial phytic acid plus zinc. Overall, the supplementation of the rat diet with phytic acid extract from sweet potato resulted in a general increase in the output of these faecal minerals.
Fast food: dietary perspectives
Authors: Jill Davies G. , Smith Jennifer L.
Published: April 2004

Consideration is given to the fast food debate in the context of a healthy diet. Fast food products readily available in retail outlets in the London area are reported on. It is apparent from this exercise that consumers can make informed choices in accord with the Balance of Good Health. Quantitative ingredient declarations on packaging clearly show, which foods are present in the order of percentage in the food product. Further information is provided through nutritional labelling. Lifestyles which demand fast foods are possibly a risk factor for gastrointestinal disturbances through eating quickly as opposed to eating fast foods per se.
Human resource management development and strategic management enhanced by simulation exercises
Authors: Trim Peter R.J.
Published: April 2004

In order to meet the challenges of the marketplace, senior management needs to ensure that an organisation employs highly skilled and well‐motivated staff, and there is a commitment to establishing a learning organisation. Simulation exercises can be used to develop the skill base of individual employees and corporate mentoring can be used to both retain and stimulate junior managers who are keen to progress through the organisation's hierarchy. This paper makes reference to a human resource management development and strategic management framework that can be used to develop a pro‐active approach to decision making. Such a framework will allow junior managers to develop a holistic awareness and appreciation of the organisation, and will provide a basis for consensus decision making. It will also foster diversity and enhance the process of communication in a multi‐cultural work environment.
Procurement of construction facilities in Guangdong Province, China: factors influencing the choice of procurement method
Authors: Smith Jim , Zheng Bing , Love Peter E.D. , Edwards David J.
Published: April 2004

Argues that the Chinese construction industry faces a daunting challenge as it slowly migrates from a planned to a market oriented economic system, particularly, with the issue of selecting the most appropriate procurement path. One of the fundamental barriers to knowledge transfer is the historically insular nature of the Chinese Government. To overcome this, a questionnaire survey was undertaken to identify the factors influencing the choice of procurement methods adopted in the Guangdong Province. Results show that quality, risk, dispute, arbitration and price certainty were the most important discriminating factors. The traditional procurement methods are regarded as the most suitable approaches for the Guangdong Province.
University‐industry partnerships
Authors: Garrick John , Chan Andrew , Lai John
Published: April 2004

In this paper it is argued that universities have lost their monopoly on the production and legitimation of knowledge. That workplaces are now sites of “valid” knowledge is a given. The information age affects many aspects of working life and we are now subject to highly automated and computerised systems and networks. This poses a range of challenges for the universities of the twenty‐first century if they are to retain their place as a vital part of the social fabric.
The LOGMAN model: a logical brand management model
Authors: Logman Marc
Published: April 2004

Proposes a model that combines the proactive and reactive nature of brand management. It is called the logical brand management model, abbreviated to the LOGMAN model. More specifically it combines insights from: Kaplan and Norton's balanced scorecard method; BCG's brand value creation method; the path analysis method; the gap analysis method; and the house of quality (QFD) method. It allows one to perform a logical brand consistency audit at several levels. It evaluates whether customer perceptions of the company's brand drivers and the external brand drivers are in line with the company's brand objectives. Furthermore, it analyzes the logical consistency of the company's brand policy across multiple customer segments and over time.
Managerial implications of computer‐based online/face‐to‐face business education: a case study
Authors: Smith Alan D. , Rupp William T.
Published: April 2004

Online business education is becoming increasingly common in tertiary education in response to the growing needs of a changing student population. E‐learning and teaching online business have unique challenges when compared to their more traditional classroom counterparts, which promotes the concepts of a nimble organisation from the managers’ perspective. A recent survey of 35 students at a major private university in Pittsburgh, Pennsylvania, who were chosen based on recent successful participation within the past calendar year in an online computer‐based college‐credit business course, were asked to respond to a number of questions concerning their personal experience with online business education. The results of this study essentially designed a profile of the typical online business education student. As increases in technology require careful consideration of its effects in the classroom for both students and practitioners, the major purpose of this research is to gauge the popularity and convenience of online education as a viable choice among students. The majority of respondents considered themselves to be either intermediate or advanced computer users; 80 percent of the respondents work either full or part‐time; 68 percent of the respondents were 25 years of age or older and all were participating in their first online business education class.
A new bacterial disease of jojoba (Simmondsia chinensis) caused by Burkholderia andropogonis
Authors: Cother E. J. , Noble D. , Peters B. J. , Albiston A. , Ash G. J.
Published: April 2004

A leaf spot of jojoba caused by Burkholderia andropogonis is described for the first time. Symptoms ranged from necrotic flecking with comparatively large watersoaked halos to larger ‘eyespot’ lesions c. 3 mm in diameter with watersoaked halos 1–1·5 mm wide. The necrosis was light tan in colour. Isolates from jojoba displayed variable pathogenicity to other known hosts of B. andropogonis (Dianthus, Cicer, Gypsophila and sorghum), but were not pathogenic, or only weakly so, to sweetcorn, Limonium and Trifolium. Identification was confirmed by cell‐wall fatty acid composition and the bacterium's possession of a single polar flagellum.
Effect of temperature on latent period of septoria leaf blotch on winter wheat under outdoor conditions
Authors: Lovell D. J. , Hunter T. , Powers S. J. , Parker S. R. , Van den Bosch F.
Published: April 2004

Batches of two winter wheat cultivars (Riband and Apollo) were inoculated with conidia of Mycosphaerella graminicola at weekly intervals over a 2 year period. Following 72 h incubation, plants were placed in ambient temperatures ranging between −7 and 32°C with mean batch temperatures of 2·9–20·2°C. Latent period until the first visible symptoms ranged between 11 and 42 days. The relationship between development of lesions and accumulated thermal time was described using a shifted cumulative gamma distribution model. The model provided good estimates of lesion development with r2 > 0·92 for both cultivars. Base temperatures, below which the pathogen did not develop, were estimated from the model as approximately −2·4°C for the two cultivars. Latent period was estimated as being 250 and 301 degree‐days above the estimated base temperature, when defined as time from inoculation to first lesion and time to 50% of maximal lesions, respectively, for cv. Riband. The values for cv. Apollo were similar, but with estimates of thermal time periods c. 5% higher. The relationship between mean temperature and inverse latent period, expressed as days either to first lesion or to 50% of maximal lesions, was best described by a linear regression with r2 > 0·96 for both cultivars. The opportunity for plants to outgrow disease was reduced when prolonged periods of cold temperature occurred, because the base temperature for growth of the pathogen was less than that for the crop.
Responses of white yam (Dioscorea rotundata) cultivars to inoculation with three viruses
Authors: Odu B. O. , Hughes J. d’A. , Asiedu R. , Ng N. Q. , Shoyinka S. A. , Oladiran O. A.
Published: April 2004

The responses of 24 white yam (Dioscorea rotundata) cultivars to mechanical and vector transmission with each of three viruses infecting yams were assessed through enzyme‐linked immunosorbent assay (ELISA) and symptom development. The viruses were Dioscorea alata virus (DAV), genus Potyvirus; Dioscorea alata bacilliform virus (DaBV), genus Badnavirus; and Cucumber mosaic virus (CMV), genus Cucumovirus. Only TDr 95‐128, a landrace cultivar from Nigeria, developed symptoms of infection with CMV and DaBV following mechanical and vector transmission, respectively. PAS‐ELISA showed that nine genotypes remained uninfected by DAV and 11 were uninfected by CMV or DaBV. Genotypes TDr 747 and TDr 1640 both showed resistance to all three viruses.
Investigating resistance toBarley mild mosaic virus
Authors: McGrann G. R. D. , Adams M. J.
Published: April 2004

There are claims that at least 11 genes confer resistance in barley (Hordeum vulgaris) to one or more components of the soilborne barley mosaic virus complex but, apart from the immunity conferred by the widely used generym4, little is known about their mode of action. This study used mechanical (sap) and plasmodiophorid vector‐inoculation techniques combined with ELISA, RT‐PCR, symptom development and virus transmission to investigate the response of different genotypes toBarley mild mosaic virus(BaMMV). Barley genotypes were grown at 20 and 12°C to test for temperature sensitivity. Plants with the genesrym3orrym6were fully susceptible to the virus, whereas those with genesrym1,Rym2,rym5orrym11appeared to be immune, as BaMMV was never detected in any tissue type nor was the virus transmitted from them to susceptible genotypes. The remaining genotypes could all be infected to some extent by BaMMV using one or both inoculation methods, and virus could be transmitted from their roots by the plasmodiophorid vectorPolymyxa graminis. Plants with therym7gene had delayed symptoms compared to susceptible controls at 12°C. Plants with therym8gene could be infected by both inoculation methods, but there was no virus in the leaves at 12°C. Plants with therym9gene could be infected only by vector inoculation, and virus remained localized in the roots. Plants with therym10gene appeared susceptible by mechanical inoculation at both temperatures, but after vector inoculation virus moved to leaves only at 20°C. This suggests the operation of translocation resistance in plants with therym8,rym9orrym10genes, which is temperature‐sensitive inrym8andrym10and perhaps tissue‐specific inrym9. No resistance toP. graminiswas observed in any of the genotypes.
Expulsion of a geopressured hydrothermal system associated with destructive earthquakes and buried active faults in the Shinanogawa Seismic Belt, Japan
Authors: Xu Huilong , Oki Yasue
Published: April 2004

Abstract  The Shinanogawa Seismic Belt in the Northern Fossa Magna, Honshu Island, Japan, extends along the Shinano River, bounding the Eurasian Plate and the Okhotsk Plate. The geopressured hydrothermal system occurs widely in the Northern Fossa Magna region. Many destructive earthquakes are related to the activity of this system in the Shinanogawa Seismic Belt. Expulsion of a geopressured hydrothermal system and rising from depth along an active fault triggers the occurrence of an earthquake and opens the fault as a pathway. Anomalous areas in temperature, electrical conductivity and Cl– concentration of groundwater trend north–east in a linear distribution, and convincingly demonstrate the presence of a buried active fault at the epicentral area of the destructive earthquake in the Shinanogawa Seismic Belt. The distribution of the major axis of the anomalous area in groundwater temperature shows a strong positive relationship with earthquake magnitude, which means that the distribution of this area may indicate the scale of earthquake fault. The linearly anomalous areas in groundwater temperature, resulting from the percolation of a geopressured hydrothermal system, that have no record of previous destructive earthquake are predicted to be areas where destructive earthquakes could occur in the future. Four potential earthquake areas are proposed and discussed in this paper, based on re‐examination of active faults and seismicity in the Shinanogawa Seismic Belt.
The Heart of the Matter 2: Integration of Ecosystemic Family Therapy Practices with Systems of Care Mental Health Services for Children and Families
Authors: Coffey Ellen Pulleyblank
Published: April 2004

Many children in this country do not receive the mental health care they need. At the same time, a nationwide movement known as systems of care is providing innovative services for families and children. This article links the ideas inherent in systems of care with ecosystemic family therapy principles and practices. Based on a study of nine innovative systems of care pilot projects in Massachusetts, it describes how these innovative programs, and others like them, have been most successful in increasing access to services and providing for coordinated services. They have been less successful in accomplishing positive clinical and functional outcomes. Change in these systems is often described in terms of how services are provided. Not enough attention is given to the conversations that take place between families and case coordinators and how these conversations lead to long‐term change. This article contends that the ways in which services are delivered in these systems of care fit well with ecosystemic family therapy principles and practices. We, as family therapists, have an opportunity to link these two sets of ideas, which share common assumptions and values and increase the likelihood of positive clinical outcomes for children and families.
Loss of N-Linked Glycosylation from the Hemagglutinin- Neuraminidase Protein Alters Virulence of Newcastle Disease Virus
Authors: Panda Aruna , Elankumaran Subbiah , Krishnamurthy Sateesh , Huang Zhuhui , Samal Siba K.
Published: April 2004

The hemagglutinin-neuraminidase (HN) protein of Newcastle disease virus (NDV) is an important determinant of its virulence. We investigated the role of each of the four functional N-linked glycosylation sites (G1 to G4) of the HN glycoprotein of NDV on its pathogenicity. The N-linked glycosylation sites G1 to G4 at residues 119, 341, 433, and 481, respectively, of a moderately pathogenic NDV strain Beaudette C (BC) were eliminated individually by site-directed mutagenesis on a full-length cDNA clone of BC. A double mutant (G12) was also created by eliminating the first and second glycosylation sites at residues 119 and 341, respectively. Infectious virus was recovered from each of the cDNA clones of the HN glycoprotein mutants, employing a reverse genetics technique. There was a greater delay in the replication of G4 and G12 mutant viruses than in the parental virus. Loss of glycosylation does not affect the receptor recognition by HN glycoprotein of NDV. The neuraminidase activity of G4 and G12 mutant viruses and the fusogenicity of the G4 mutant virus were significantly lower than those of the parental virus. The fusogenicity of the double mutant virus (G12) was significantly higher than that of the parental virus. Cell surface expression of the G4 virus HN was significantly lower than that of the parental virus. The antigenic reactivities of the mutants to a panel of monoclonal antibodies against the HN protein indicated that removal of glycosylation from the HN protein increased (G1, G3, and G12) or decreased (G2 and G4) the formation of antigenic sites, depending on their location. In standard tests to assess virulence in chickens, all of the glycosylation mutants were less virulent than the parental BC virus, but the G4 and G12 mutants were the least virulent.
Use of gHgL for Attachment of Epstein-Barr Virus to Epithelial Cells Compromises Infection
Authors: Borza Corina M. , Morgan Andrew J. , Turk Susan M. , Hutt-Fletcher Lindsey M.
Published: April 2004

Epstein-Barr virus (EBV) is a lymphotropic herpesvirus. However, access to B lymphocytes during primary infection may be facilitated by replication in mucosal epithelial cells. Attachment and penetration of EBV into these two cell types are fundamentally different. Both the distribution of receptors and the cellular origin of the virus impact the efficiency of infection. Epithelial cells potentially offer a wide range of receptors with which virus can interact. We report here on analyses of epithelial cells expressing different combinations of receptors. We find that the stoichiometry of the virus glycoprotein complex that includes gHgL and gp42 affects the use of gHgL not just for entry into epithelial cells but also for attachment. Penetration can be mediated efficiently with either a coreceptor for gp42 or gHgL, but the use of gHgL for attachment as well as penetration greatly compromises its ability to mediate entry.
Requirement for Integrase during Reverse Transcription of Human Immunodeficiency Virus Type 1 and the Effect of Cysteine Mutations of Integrase on Its Interactions with Reverse Transcriptase
Authors: Zhu Kai , Dobard Charles , Chow Samson A.
Published: April 2004

Retroviral integrase catalyzes the essential step of integrating a double-stranded DNA copy of the viral genome into a host cell chromosome. Mutational studies have revealed that integrase is involved in additional steps of viral replication, but the mechanism for the pleiotropic effect is not well characterized. Since Cys residues generally play crucial roles in protein structure and function, we introduced Cys-to-Ser substitutions at positions 56, 65, and 130 of human immunodeficiency virus type 1 (HIV-1) integrase to determine their effects on integration activity and viral replication. None of the substitutions significantly affected the enzymatic activities in vitro. When introduced into the NL4-3 molecular clone of HIV-1, mutant viruses encoding Cys mutations at positions 56 and 65 of integrase replicated similarly to the wild-type virus in CD4
+
-T-cell lines, whereas the C130S-containing virus was noninfectious. The entry and postintegration steps of the viral life cycle for all mutant viruses were normal, and all had particle-associated reverse transcriptase (RT) activity. However, early reverse-transcribed DNA products were absent in the lysate of cells infected with the C130S mutant virus, indicating that the mutation abolished the ability of the virus to initiate endogenous reverse transcription. Coimmunoprecipitation using purified integrase and RT showed that the C-terminal domain of wild-type HIV-1 integrase interacted with RT. The interaction between integrase and RT was not affected in the presence of a reducing or alkylating agent, suggesting that the interaction did not involve a disulfide linkage. The C130S substitution within the core region may disrupt the protein recognition interface of the C-terminal domain and abolish its ability to interact with RT. Our results indicate that integrase plays an important role during the reverse-transcription step of the viral life cycle, possibly through physical interactions with RT.
Identification of Unique Hepatitis C Virus Quasispecies in the Central Nervous System and Comparative Analysis of Internal Translational Efficiency of Brain, Liver, and Serum Variants
Authors: Forton Daniel M. , Karayiannis Peter , Mahmud Nadiya , Taylor-Robinson Simon D. , Thomas Howard C.
Published: April 2004

Reports of cerebral dysfunction in chronic hepatitis C virus (HCV) infection have led to the suggestion that HCV may infect the central nervous system (CNS). We used reverse transcription-PCR, cloning, and sequencing to define quasispecies for the HCV internal ribosomal entry site (IRES) and hypervariable region 1 (HVR1) in autopsy-derived brain, liver, lymph node, and serum samples. There was evidence of tissue compartmentalization of sequences in the brain in two patients, with between 24 and 55% of brain-derived IRES sequences absent from the serum, and significant phylogenetic and phenetic clustering of the brain and lymph node HVR1 sequences. The IRES initiates cap-independent translation of the viral polyprotein. Two unique brain-derived IRES mutations (C
204
→A and G
243
→A), which have previously been associated with lymphoid replication and altered translational efficiency in cell culture, were found in one patient. We used a dicistronic reporter vector to test whether brain-derived variants showed altered IRES-mediated translational efficiency, which might favor CNS infection. The translational efficiencies of the brain-derived IRES sequences were generally reduced compared to those of the master serum and liver sequences in rabbit reticulocyte cell lysates and two human cell lines, HuH7 (liver) and CHME3 (microglial). The C
204
→A and G
243
→A mutations showed preserved translational efficiency in HuH7 cells but reduced efficiency in CHME3 cells. Our data provide evidence that the CNS is a site of HCV replication, consistent with the recent demonstration of negative-strand HCV RNA in brain, and suggest that IRES polymorphisms may be important as a viral strategy of reduced translation to favor latency in the CNS.
CD4+T Cells from CD4C/HIVNefTransgenic Mice Show Enhanced Activation In Vivo with Impaired Proliferation In Vitro but Are Dispensable for the Development of a Severe AIDS-Like Organ Disease
Authors: Weng Xiaoduan , Priceputu Elena , Chrobak Pavel , Poudrier Johanne , Kay Denis G. , Hanna Zaher , Mak Tak W. , Jolicoeur Paul
Published: April 2004

The cellular and molecular mechanisms of dysfunction and depletion of CD4+T lymphocytes over the course of human immunodeficiency virus type 1 (HIV-1) infection are still incompletely understood, but chronic immune activation is thought to play an important role in disease progression. We studied CD4+T-cell biology in CD4C/HIV transgenic (Tg) mice, in which Nef expression is sufficient to induce a severe AIDS-like disease including a preferential decrease of CD4+T cells. We show here that Nef-expressing Tg CD4+T cells exhibit an activated/memory-like phenotype which appears to be independent of antigenic stimulation, as documented in experiments involving breeding with AD10 TcR Tg mice. In addition, in vivo bromodeoxyuridine incorporation showed that a larger proportion of Tg than non-Tg CD4+T cells entered the S phase. However, in vitro, Tg CD4+T cells were found to have a very limited capacity to divide in response to stimulation with anti-CD3 and anti-CD28 or in allogeneic mixed leukocyte reactions. Interestingly, despite these observations, the deletion of Tg CD4+T cells had little impact on the development of other AIDS-like organ phenotypes. Thus, the Nef-induced chronic activation of CD4+T cells may exhaust the T-cell pool and may contribute to the thymic atrophy and the low number of CD4+T cells observed in these Tg mice.