bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermophoresis of an aerosol spheroid along its axis of revolution
Authors: Keh Huan J. , Chang Yu C.
Published: June 2009

The thermophoretic motion of a spheroidal particle freely suspended in a gaseous medium prescribed with a uniform temperature gradient along the axis of revolution of the particle is studied theoretically in the steady limit of small Peclet and Reynolds numbers. The Knudsen number is assumed to be small so that the fluid flow is described by a continuum model with a temperature jump, a thermal slip, and a frictional slip at the particle surface. The general solutions in prolate and oblate spheroidal coordinates can be expressed in infinite-series forms of separation of variables for the temperature distribution and of semiseparation of variables for the stream function. The jump/slip boundary conditions on the particle surface are applied to these general solutions to determine the unknown coefficients of the leading orders, which can be numerical results obtained from a boundary-collocation method or explicit formulas derived analytically. Numerical results for the thermophoretic velocity of the spheroidal particle are obtained in a broad range of its aspect ratio with good convergence behavior for various cases. For the axisymmetric thermophoresis of an aerosol spheroid, prolate, or oblate, with no temperature jump and frictional slip at its surface, our results agree excellently with the analytical solution obtained previously. The agreement between our results and the available numerical solutions obtained by using a singularity method is also very good. For most practical cases of a spheroid with a specified aspect ratio, the thermophoretic mobility of the particle is not a monotonic function of its relative jump/slip coefficients and thermal conductivity. The axisymmetric thermophoretic mobilities of a prolate spheroid and of an oblate spheroid with large aspect ratios can be much greater and smaller, respectively, than that of a sphere with the same equatorial radius.
Poiseuille flow and thermal creep based on the Boltzmann equation with the Lennard-Jones potential over a wide range of the Knudsen number
Authors: Sharipov Felix , Bertoldo Guilherme
Published: June 2009

The methodology to solve the linearized Boltzmann equation for an arbitrary potential of intermolecular interaction described in our previous paper [F. Sharipov and G. Bertoldo, J. Comput. Phys. 228, 3345 (2009)] is used to calculate a rarefied gas flow between two parallel plates driven by pressure and temperature gradients over a wide range of the Knudsen number. As an example, the Lennard-Jones potential is applied. The calculations were carried out for all noble gases at the temperature equal to 300 K. A comparison with results for the same problem based on the kinetic model equations showed that the uncertainty of these equations has the same order that the Boltzmann equation based on the hard sphere particles.
Fracture toughness and crack-resistance curve behavior in metallic glass-matrix composites
Authors: Launey M. E. , Hofmann D. C. , Suh J.-Y. , Kozachkov H. , Johnson W. L. , Ritchie R. O.
Published: June 2009

Nonlinear-elastic fracture mechanics methods are used to assess the fracture toughness of bulk metallic glass (BMG) composites; results are compared with similar measurements for other monolithic and composite BMG alloys. Mechanistically, plastic shielding gives rise to characteristic resistance-curve behavior where the fracture resistance increases with crack extension. Specifically, confinement of damage by second-phase dendrites is shown to result in enhancement of the toughness by nearly an order of magnitude relative to unreinforced glass.
Electro-optic modulation in slotted resonant photonic crystal heterostructures
Authors: Wülbern Jan Hendrik , Hampe Jan , Petrov Alexander , Eich Manfred , Luo Jingdong , Jen Alex K.-Y. , Di Falco Andrea , Krauss Thomas F. , Bruns Jürgen
Published: June 2009

Two dimensional photonic crystal waveguides in high index materials enable integrated optical devices with an extremely small geometrical footprint on the scale of micrometers. Slotted waveguides are based on the guiding of light in low refractive index materials and a field enhancement in this particular region of the device. In this letter we experimentally demonstrate electro-optic modulation in slotted photonic crystal waveguides based on silicon-on-insulator substrates covered and infiltrated with nonlinear optical polymers. A photonic crystal heterostructure is used to create a cavity, while simultaneously serving as an electrical connection from the slot to the metal electrodes that carry the modulation signal.
Near-infrared silicon quantum dots metal-oxide-semiconductor field-effect transistor photodetector
Authors: Shieh Jia-Min , Yu Wen-Chien , Huang Jung Y. , Wang Chao-Kei , Dai Bau-Tong , Jhan Huang-Yan , Hsu Chih-Wei , Kuo Hao-Chung , Yang Fu-Liang , Pan Ci-Ling
Published: June 2009

A fully silicon-based metal-oxide-semiconductor field-effect transistor is demonstrated for the detection of near-infrared light. Si nanocrystals (nc-Si) are synthesized in the nanopore channels of mesoporous silica (MS) inserted between two oxide layers to form a complete gate structure of polycrystalline Si/SiO2/nc-Si-in-MS/SiO2 with a polycrystalline Si electrode. Illuminating the gate with near-infrared light, a photoresponsivity as high as 2.8 A/W at 1.55 μm can be achieved. The improved photoresponsivity is attributed to from optical transitions via interface states and a current amplification mechanism of the device.
Enhancement in tunnel magnetoresistance effect by inserting CoFeB to the tunneling barrier interface in Co2MnSi/MgO/CoFe magnetic tunnel junctions
Authors: Tsunegi S. , Sakuraba Y. , Oogane M. , Naganuma Hiroshi , Takanashi K. , Ando Y.
Published: June 2009

Tunnel magnetoresistance (TMR) effect was investigated in Co2MnSi/CoFeB(0–2 nm)/MgO/CoFe magnetic tunnel junctions (MTJs). TMR ratio was enhanced by inserting a thin CoFeB layer at the Co2MnSi/MgO interface. The MTJ with CoFeB thickness of 0.5 nm exhibited the highest TMR ratio. From the conductance-voltage measurements for the fabricated MTJs, we infer that the highly spin polarized electron created in Co2MnSi can conserve the polarization through the 0.5-nm-thick CoFeB layer. Furthermore, by insertion of the thin CoFeB layer, the temperature dependence of the TMR ratio was improved because of the suppression of the fluctuation of the magnetic moment at the Co2MnSi/MgO interface.
Excitation of propagating surface plasmons by a periodic nanoparticle array: Trade-off between particle-induced near-field excitation and damping
Authors: Ghoshal Amitabh , Kik Pieter G.
Published: June 2009

The excitation of propagating surface plasmons (SPs) on a silver-silica interface by an array of ellipsoidal silver nanoparticles is investigated using numerical simulations as a function of particle volume for three different nanoparticle aspect ratios with representative resonance frequencies. We find that while the SP amplitude depends sensitively on particle volume for each selected aspect ratio, the maximum SP amplitude obtained for the different particle shapes is remarkably similar. These observations are explained in terms of particle-mediated SP excitation, counteracted by a size dependent particle-induced damping. An analytical model is presented that quantitatively describes the observed trends in SP damping.
The complex evolution of strain during nanoscale patterning of 60 nm thick strained silicon layer directly on insulator
Authors: Moutanabbir O. , Reiche M. , Erfurth W. , Naumann F. , Petzold M. , Gösele U.
Published: June 2009

The strain behavior in nanoscale patterned biaxial tensile strained Si layer on insulator is investigated in 60-nm-thick nanostructures with dimensions in the 80–400 nm range. The in-plane strain is evaluated by using UV micro-Raman. We found that less than 30% of the biaxial strain is maintained in the 200×200 nm2 nanostructures. This relaxation, due to the formation of free surfaces, becomes more important in smaller nanostructures. The strain is completely relieved at 80 nm. This phenomenon is described based on detailed three-dimensional finite element simulations. The anisotropic relaxation in rectangular nanostructures is also discussed.
Formation of a dual hydrogen bond in the N–H⋯C=O moiety in the indole-(N-methylacetamide)1 cluster revealed by IR-dip spectroscopy with natural bond orbital analysis
Authors: Sakota Kenji , Shimazaki Yuiga , Sekiya Hiroshi
Published: June 2009

IR-dip spectra in the NH stretch regions have been measured for the S0 state of the indole/N-methylacetamide 1:1 clusters (Ind-NMA1). We identified two structural isomers of Ind-NMA1 that possess an N–H⋯O=C hydrogen bond. The redshifts of the NH stretch fundamental of the indole moieties in Ind-NMA1 are larger than that for Ind-(H2O)1 [Carney, Hagemeister, and Zweir, J. Chem. Phys. 108, 3379 (1998)], indicating that the strength of the N–H⋯O=C hydrogen bond in Ind-NMA1 is stronger than that of the N–H⋯O–H hydrogen bond in Ind-(H2O)1. On the basis of the natural bond orbital analysis we suggest that two lone pair orbitals of the O atoms in the NMA moiety form a dual hydrogen bond with the NH group designated by N–H:::O=C. Owing to the dual nature of the N–H:::O=C hydrogen bond its strength in Ind-NMA1 is larger than that of the N–H⋯O–H hydrogen bond in Ind-(H2O)1.
Electrochemical growth of n-ZnO onto the p-type GaN substrate: p-n heterojunction characteristics
Authors: Asıl H. , Gür Emre , Çınar K. , Coşkun C.
Published: June 2009

n -ZnO thin films were deposited electrochemically onto the p-GaN/Al2O3 substrate in order to form hetero p-n junction. X-ray diffraction measurement has been showed clearly (0002) c-axis orientation of grown ZnO thin film. Absorption measurements were carried out before and after growth process indicating both sharp absorption edges of GaN and ZnO thin films. Photoluminescence measurement shows n-ZnO film grown on p-GaN has a dominant emission at 2.8 eV. I-V characteristic of n-ZnO/p-GaN/Al2O3 heterojunction showed that almost five order of rectification has been achieved. Turn on voltages of the p-n heterojunction is found to be 1.12 V.
Specular electron scattering at single-crystal Cu(001) surfaces
Authors: Chawla J. S. , Gall D.
Published: June 2009

Epitaxial copper layers, 20 nm to 1.5-μm-thick, were grown on MgO(001) by ultrahigh vacuum magnetron sputter deposition at 80 °C. In situ electrical resistivity measurements indicate partial specular scattering at the Cu vacuum interface with a Fuchs–Sondheimer scattering parameter p=0.6±0.1. In situ deposition of 0.3 to 7.0-nm-thick Ta cap layers on the Cu surfaces leads to a resistivity increase, which is independent of the Ta thickness and is associated with a transition to completely diffuse surface scattering with p=0.0±0.1. The diffuse scattering is attributed to a “rough” electron potential at the Cu–Ta interface as well as to scattering into localized interface and surface states.
Exchange bias in zinc-blende CrTe–MnTe bilayer
Authors: Bi J. F. , Lu H. , Sreenivasan M. G. , Teo K. L.
Published: June 2009

We have studied the exchange bias at the ferromagnetic (FM)/antiferromagnetic interface in the zinc-blende transition-metal chalcogenides, CrTe (5 nm)/MnTe(40 nm) bilayer grown on GaAs (100) substrate by molecular-beam epitaxy. A negative exchange bias shift in the hysteresis loop is observed when the bilayer is cooled in the applied magnetic field. The temperature-dependent remanent magnetization shows a clear enhancement of the Curie temperature and magnetization in the bilayer as compared to a single FM layer. The effects of temperature, cooling field, and angular dependence on the exchange bias have been investigated.
Optical properties of GaSb-based type II quantum wells as the active region of midinfrared interband cascade lasers for gas sensing applications
Authors: Motyka M. , Sęk G. , Ryczko K. , Misiewicz J. , Lehnhardt T. , Höfling S. , Forchel A.
Published: June 2009

Photoreflectance and photoluminescence, supported by the energy level calculations in the eight-band k⋅p model including strain, have been used to study the optical properties of GaSb/AlSb/InAs/InGaSb/AlSb/GaSb type II quantum wells (QWs). The broad emission wavelength tunability in the midinfrared range has been demonstrated by the control of InAs layer thickness. The temperature dependent measurements have shown that the emission can still be efficient at room temperature in such structures, and that the temperature shift of the fundamental type II optical transition between 10 and 300 K can be significantly smaller than for type I QW systems.
Comment on “On the Crooks fluctuation theorem and the Jarzynski equality” [J. Chem. Phys. 129, 091101 (2008)]
Authors: Adib Artur B.
Published: June 2009

It has recently been argued that a self-consistency condition involving the Jarzynski equality (JE) and the Crooks fluctuation theorem (CFT) is violated for a simple Brownian process [L. Y. Chen, J. Chem. Phys.129, 091101 (2008)]. This note adopts the definitions in the original formulation of the JE and CFT and demonstrates the contrary.
Ultrafast all-optical light modulation in the near infrared region by phase sensitive polymer guided wave mode geometry containing porphyrin tapes
Authors: Matsumoto Ryuji , Nagamura Toshihiko , Aratani Naoki , Ikeda Toshiaki , Osuka Atsuhiro
Published: June 2009

A phase sensitive detection was introduced into reflection type all-optical light modulation based on guided wave mode (GWM) geometry. A polymer film containing a copper porphyrin tape and a low refractive polymer film formed GWM at specific incident angle and wavelength. Sensitive changes of output intensity were observed upon femtosecond laser excitation depending on azimuthal angles of the analyzer, which was caused by phase changes at the GWM by Δk alone. The present system has a great advantage as compared with the conventional GWM or simple transmission methods for all-optical light modulation especially for materials showing the ground state absorption.
Dual-function phase shifter for spin-wave logic applications
Authors: Hansen Ulf-Hendrik , Demidov Vladislav E. , Demokritov Sergej O.
Published: June 2009

We have studied experimentally the linear and nonlinear control over the phase accumulation in a spin-wave phase shifter, which is a key element for construction of spin-wave logic devices. The linear control is realized by creation of a local inhomogeneity of the bias magnetic field, whereas the nonlinear control is based on the shift in the spin-wave dispersion spectrum with the increase in the spin-wave amplitude. We show that in a single device these two mechanisms can have comparable efficiencies and relatively small cross talk, which allows their simultaneous use for realization of dual-argument logic operations.
The Spatial Structuring of Interurban Housing Markets: Application to Building Sites Prepared for Self-Provided Housing
Authors: Halleux Jean-Marie
Published: June 2009

The author supports the argument that a focus on the spatiality of economic mechanisms can be a valuable way to address the issue of interurban housing markets, a theme which has not yet been adequately addressed by academic research. Developments are based on a theoretical framework in which two factors are considered central to the structuring of markets: (i) the possibility of choice between substitutable supplies (spatially related to the territory prospected by the consumer), and (ii) the availability of information on the state of the market (spatially related to the use of local sales references when market participants prepare their negotiations). This theoretical framework is empirically applied to the case of building sites prepared for self-built housing, with a modelling methodology elaborated for Belgium. The modelling methodology, based on cross-sectional regressions, develops a spatial autoregressive specification and incorporates a multiscale comparison. By highlighting the importance of information availability and demand substitutability, this exercise confirms that a focus on interurban market spatiality can be helpful to housing researchers. In fact, the results suggest that such a focus is particularly appropriate to the analysis of the impact of planning regulations on market outcomes.
Social Sustainability and Urban Form: Evidence from Five British Cities
Authors: Bramley Glen , Dempsey Nicola , Power Sinead , Brown Caroline , Watkins David
Published: June 2009

Planning and urban policies emphasise ‘sustainability’, but claims that ‘compact cities' are more socially sustainable and acceptable have been controversial and subject to limited empirical testing. After a brief review of the concepts and debate, we set out new empirical evidence based on household surveys linked to neighbourhood physical, map-based, and sociodemographic data for five British cities. Statistical models are developed to account for systematic variations in the main social sustainability outcomes. The results are considered both in terms of the role of particular urban form and locational measures, but also in terms of the broader patterns of effects of packages of measures. Outcomes relating to residential satisfaction, stability, neighbourhood environment, and safety are all shown to be lower in higher density/central places, but it is also shown that a good deal of this apparent effect is due to social and demographic factors. Interaction with neighbours and participation in groups is better at medium densities, controlling for other factors, while use of local services is, as expected, greater in denser, more central locations. These findings indicate that compact cities are not ‘win-win’ on all dimensions of sustainability but, rather, that reductions in transport emissions will have to be weighed against social criteria. In addition, urban form has different aspects, which have differing social effects, and this knowledge could inform the future design of ‘smarter’ urban environments.
Auditory Induced Bounce Perception Persists as the Probability of a Motion Reversal is Reduced
Authors: Grove Philip M , Sakurai Kenzo
Published: June 2009

When two identical targets move toward one another from opposite sides of a display and continue past one another along collinear trajectories, they can be perceived to either stream past or bounce off of one another. Streaming is the dominant perception in motion displays free of additional transients, while bouncing predominates when a transient (eg auditory or visual) is presented at the point of coincidence. We investigated whether the auditory induced bias towards bouncing would persist as the probability of a motion reversal was reduced by introducing a spatial offset either vertically in a 2-D display or in depth in a 3-D display. Offset conditions were combined with two auditory conditions (tone or no-tone at the point of coincidence) in the presence or absence of a central occluder. In conditions with no sound, streaming was reported on a clear majority of trials, regardless of spatial offset. When a transient tone was presented, reported motion reversals dominated and persisted for increasing verbal offsets up to 17.9 min of arc and for 3-D trajectory offsets up to 25.6 min of arc. The bounce-promoting effect of an auditory tone at the point of coincidence in stream/bounce displays persists in spite of rendering the visual motion sequence unambiguous and more consistent with streaming.
Narrowing of intersensory speech perception in infancy
Authors: Pons Ferran , Lewkowicz David J. , Soto-Faraco Salvador , Sebastián-Gallés Núria
Published: June 2009

The conventional view is that perceptual/cognitive development is an incremental process of acquisition. Several striking findings have revealed, however, that the sensitivity to non-native languages, faces, vocalizations, and music that is present early in life declines as infants acquire experience with native perceptual inputs. In the language domain, the decline in sensitivity is reflected in a process of perceptual narrowing that is thought to play a critical role during the acquisition of a native-language phonological system. Here, we provide evidence that such a decline also occurs in infant response to multisensory speech. We found that infant intersensory response to a non-native phonetic contrast narrows between 6 and 11 months of age, suggesting that the perceptual system becomes increasingly more tuned to key native-language audiovisual correspondences. Our findings lend support to the notion that perceptual narrowing is a domain-general as well as a pan-sensory developmental process.
Contingencies and compounded rare perturbations dictate sudden distributional shifts during periods of gradual climate change
Authors: Harley Christopher D. G. , Paine Robert T.
Published: June 2009

Ecological responses to climate change may occur gradually with changing conditions, or they may occur rapidly once some threshold or “tipping point” has been reached. Here, we use a high-resolution, 30-year data set on the upper vertical limit of a high intertidal alga to demonstrate that distributional shifts in this species do not keep pace with gradual trends in air temperature or sea level, but rather occur in sudden, discrete steps. These steps occur when unusually warm air temperatures are associated with unusually calm seas and are contingent in the sense that neither atmospheric nor sea conditions by themselves were sufficient to generate the underlying physiological challenge. Shifts in the upper limit did not correlate with large environmental perturbations such as El Niños; rather, they appeared to be associated with stochastic departures from otherwise gradual environmental trends. Our results exemplify the view that multiple environmental factors should be considered when attempting to understand ecological responses to climate change. Furthermore, punctuated responses such as those we have identified urge caution when attempting to infer causal mechanisms and project future distributional shifts using data of limited temporal resolution or scope.
The Role of the Exocyst in Matrix Metalloproteinase Secretion and Actin Dynamics during Tumor Cell Invadopodia Formation
Authors: Liu Jianglan , Yue Peng , Artym Vira V. , Mueller Susette C. , Guo Wei
Published: June 2009

Invadopodia are actin-rich membrane protrusions formed by tumor cells that degrade the extracellular matrix for invasion. Invadopodia formation involves membrane protrusions driven by Arp2/3-mediated actin polymerization and secretion of matrix metalloproteinases (MMPs) at the focal degrading sites. The exocyst mediates the tethering of post-Golgi secretory vesicles at the plasma membrane for exocytosis and has recently been implicated in regulating actin dynamics during cell migration. Here, we report that the exocyst plays a pivotal role in invadopodial activity. With RNAi knockdown of the exocyst component Exo70 or Sec8, MDA-MB-231 cells expressing constitutively active c-Src failed to form invadopodia. On the other hand, overexpression of Exo70 promoted invadopodia formation. Disrupting the exocyst function by siEXO70 or siSEC8 treatment or by expression of a dominant negative fragment of Exo70 inhibited the secretion of MMPs. We have also found that the exocyst interacts with the Arp2/3 complex in cells with high invasion potential; blocking the exocyst-Arp2/3 interaction inhibited Arp2/3-mediated actin polymerization and invadopodia formation. Together, our results suggest that the exocyst plays important roles in cell invasion by mediating the secretion of MMPs at focal degrading sites and regulating Arp2/3-mediated actin dynamics.
CSN-5, a Component of the COP9 Signalosome Complex, Regulates the Levels of UNC-96 and UNC-98, Two Components of M-lines inCaenorhabditis elegansMuscle
Authors: Miller Rachel K. , Qadota Hiroshi , Stark Thomas J. , Mercer Kristina B. , Wortham Tesheka S. , Anyanful Akwasi , Benian Guy M.
Published: June 2009

In Caenorhabditis elegans two M-line proteins, UNC-98 and UNC-96, are involved in myofibril assembly and/or maintenance, especially myosin thick filaments. We found that CSN-5, a component of the COP9 signalosome complex, binds to UNC-98 and -96 using the yeast two-hybrid method. These interactions were confirmed by biochemical methods. The CSN-5 protein contains a Mov34 domain. Although one other COP9 signalosome component, CSN-6, also has a Mov34 domain, CSN-6 did not interact with UNC-98 or -96. Anti-CSN-5 antibody colocalized with paramyosin at A-bands in wild type and colocalized with abnormal accumulations of paramyosin found in unc-98, -96, and -15 (encodes paramyosin) mutants. Double knockdown of csn-5 and -6 could slightly suppress the unc-96 mutant phenotype. In the double knockdown of csn-5 and -6, the levels of UNC-98 protein were increased and the levels of UNC-96 protein levels were slightly reduced, suggesting that CSN-5 promotes the degradation of UNC-98 and that CSN-5 stabilizes UNC-96. In unc-15 and unc-96 mutants, CSN-5 protein was reduced, implying the existence of feed back regulation from myofibril proteins to CSN-5 protein levels. Taken together, we found that CSN-5 functions in muscle cells to regulate UNC-98 and -96, two M-line proteins.
PhyloBayes 3: a Bayesian software package for phylogenetic reconstruction and molecular dating
Authors: Lartillot Nicolas , Lepage Thomas , Blanquart Samuel
Published: June 2009

Motivation: A variety of probabilistic models describing the evolution of DNA or protein sequences have been proposed for phylogenetic reconstruction or for molecular dating. However, there still lacks a common implementation allowing one to freely combine these independent features, so as to test their ability to jointly improve phylogenetic and dating accuracy.

Results: We propose a software package, PhyloBayes 3, which can be used for conducting Bayesian phylogenetic reconstruction and molecular dating analyses, using a large variety of amino acid replacement and nucleotide substitution models, including empirical mixtures or non-parametric models, as well as alternative clock relaxation processes.

Availability: PhyloBayes is freely available from our web site http://www.phylobayes.org. It works under Linux, Mac OsX and Windows operating systems.

Contact:  nicolas.lartillot@umontreal.ca

Supplementary information:  Supplementary data are available at Bioinformatics online.
Principles of Heart Failure
Authors: De Silva Kalpa , Katbamna Raakhee
Published: June 2009

On average, a general practitioner, who works with an average practice list size of 6000 people, will look after 30 patients with chronic heart failure and suspect a new diagnosis of heart failure in approximately 10 patients annually.
Knee Pain
Authors: Mehrali Tauseef H , Yunas Idnan
Published: June 2009

Knee pain is a common presenting symptom in primary care. Around 4.5 million people in the UK, over 100 patients per GP, have severe or disabling knee pain. About 25% of people over the age of 55 years complain of chronic knee pain which is usually diagnosed as osteoarthritis. At the other end of the age spectrum, knee pain affects as many as one in three teenagers and young adults at some time or other.
Adult Self-Directed Learning: Setting Your Own Agenda
Authors: Hays Richard
Published: June 2009

Medical education often uses terms like ‘adult learning’ and ‘self-directed learning’. We are told that we trained to be self-directed and adult learners from the commencement of basic medical education and that this is important if we are to remain competent over a career that may span 30–40 years. However, the ability to be an adult or self-directed learner is difficult to measure and it is therefore difficult to determine whether these processes (or are they skills?) are either innate or learnable. There is a risk that the terms are seen simply as impractical educational jargon, and so education organizations feel safest when they provide a tightly structured curriculum and assess learners through examinations based on that curriculum. The Postgraduate Medical Education Training Board has required this for all postgraduate specialties, including general practice. The obvious question then is ‘what happens next?’ as there is no such thing as a curriculum for lifelong competence. There is therefore a need for GP registrars, as part of the new RCGP curriculum, to develop the skills to be lifelong learners for two reasons. The first is to facilitate maintaining currency of practice and the second is to role model that for other learners. This paper aims to explain in simple terms how, in the context of being on the pathway to becoming an independent general practitioner, the theory can be applied to enhance adult and self-directed learning in GP registrars.
Application of the Humid Thermal Index for Relating Bunted Kernel Incidence to Soilborne Tilletia indica Teliospores in an Arizona Durum Wheat Field
Authors: Allen T. W. , Jones D. C. , Boratynski T. N. , Ykema R. E. , Rush C. M.
Published: June 2009

A study was conducted to determine the relationship between soilborne Tilletia indica teliospore density and Karnal bunt incidence in an Arizona durum wheat field in 2005 and 2006. Soil samples were collected from 507 sample points according to a grid marked in a 7.7-ha field. Approximately 500 g of soil from the top 5 cm was collected from each sample point, and teliospores were recovered from 25-g aliquots by a modified size-selective sieving, sucrose centrifugation procedure. Twenty-five and 50 wheat heads were collected from a 1-m2 area around each sample point in May 2005 and June 2006, respectively. Wheat head samples from each sample point were bulked, threshed, and examined for the presence of bunted kernels. Additionally, data for soilborne teliospores and percent bunted kernels from 70 sample points in 2005 and 2006 that corresponded to sample points from a 2004 bunted kernel survey conducted by the USDA and Arizona Department of Agriculture were analyzed. Soilborne teliospore numbers ranged from 6 to 1,000 per 25-g soil sample in the 2-year study. No bunted kernels were recovered in 2005; however, two sample points yielded bunted kernels in 2006. Weather data from three time periods in 2004, 2005, and 2006 were applied to the humid thermal index model and suggested that a conducive environment for disease development existed in 2005. Based on the data from this research, we concluded that even though high numbers of soilborne teliospores were present in the field, and although a conducive environment was present for disease to develop on only one occasion, a direct relationship between soilborne teliospores and disease incidence may not exist.
First Report of Soybean mosaic virus on Soybean in North Dakota
Authors: Nelson B. D. , Domier L. L.
Published: June 2009

Soybean, Glycine max L, is grown on 1,420,000 ha in North Dakota and is the most important oilseed crop in the state. Viruses in soybean have not previously been reported from North Dakota (2). In July and August of 2007, 64 soybean fields in Cass, Richland, and Sargent counties in southeastern North Dakota were surveyed for Soybean mosaic virus (SMV). These counties have a high concentration of soybean hectares, a long history of soybean production, and soybean aphid infestations that were observed in 2004 and 2006. Fields were sampled with a grid pattern across the area with at least 8 km (5 miles) between fields. A transect of approximately 60 m through each field was made and 20 leaves were collected at random. Sap was extracted in phosphate buffer and stored at –80°C until tested first using double antibody sandwich (DAS)-ELISA with positive controls and reagents and protocol from Agdia Inc. (Elkhart, IN). Using DAS-ELISA, SMV was detected in 19 of the 64 soybean fields sampled. To confirm the presence of SMV, 12 samples that were positive for SMV by DAS-ELISA also were tested by reverse transcription (RT)-PCR. RNA was extracted from sap by a Qiagen RNeasy Plant Mini Kit (Germantown, MD), reverse transcribed, and amplified with SuperScrip III Platinum SYBR Green One-Step qRT-PCR Kit (Invitrogen Inc., Carlsbad, CA) and SMV-specific primers (5′-TTCAGCACAATGGGTGAGGATG-3′ and 5′-AATTCTGTGTGGCTTGATGTTGC-3′) (1). Eight of the twelve ELISA-positive samples were positive for SMV by RT-PCR, confirming the presence of SMV in the samples. To our knowledge, this is the first report of SMV infecting soybean in North Dakota.

References: (1) L. L. Domier et al. (Abstr.). Phytopathology 98(suppl.):S47, 2008. (2) B. D. Nelson and G. Danielson. (Abstr.). Phytopathology 95(suppl.):S164, 2005.
First Report of Onion yellow dwarf virus in Allium chinense in China
Authors: Wu C. C. , Hong N. , Liu Y. , Xu W. X. , Wang G. P.
Published: June 2009

Allium chinense (G. Don) is an economically important vegetable that has been considered to be of Asian origin (2). In April of 2007, plants of cultivated A. chinense showing mosaic, chlorotic streak, twist, and crinkle on leaves were collected from fields at Jiangxia, a suburban district of Wuhan, Hubei Province, China, and transplanted into pots in a greenhouse. Ultrathin sections of diseased leaves were observed under an electron microscope. Pinwheel or cylindrical inclusions, typical of a potyvirus infection, were observed. Filamentous virus particles (820 nm long) were also observed in the crude extract from the same plant. To identify the virus species, viral RNAs were extracted from partially purified virion preparation (3) and used as a template. First-strand cDNA was synthesized with M4-T (5′-GTT TTC CCA GTC ACG AC (T)15-3′) as a complementary primer. The 3′-terminus of viral RNA was amplified using primer M4 (5′-GTT TTC CCA GTC ACG AC-3′) in combination with a degenerate primer (5′-GGXAAYAAYAGY GGX CARCC-3′) that was specific for potyviruses (1). Amplified products were cloned and nine clones were sequenced. Sequence analysis showed that the size of the amplified fragment, excluding the poly A tail, was 1,625 bp, which had the typical characteristics of the 3′-terminus of the potyvirus genome, including the partial NIb gene (636 bp) and the complete coat protein (CP gene; 771 bp). The 1,625-bp sequence from A. chinense (Genbank Accession No. FJ765739) had the highest identity at the nucleotide level with sequences of Onion yellow dwarf virus (OYDV), ranging from 76% (Genbank Accession Nos. AB219833 and AB219834) to 99% (Genbank Accession No. AJ409313). The CP gene had 88% (Genbank Accession Nos. AB219833 and AB219834) to 99% (Genbank Accession Nos. AJ409313 and AJ409310) identity at the amino acid level with corresponding regions of known OYDV isolates from other hosts. Until now, only Scallion mosaic virus (ScaMV), in the genus Potyvirus, had been detected from A. chinense (1); however, OYDV was reported in rakkyo, the same species as Chinese scallion, in Japan (4). To our knowledge, this is the first report of OYDV infecting A. chinense in China.

References: (1) J. Chen et al. Arch. Virol. 147:683, 2002. (2) L. K. Mann and W. T. Stearn. Econ. Bot. 14:69, 1960. (3) T. Nagakubo et al. Phytopathology 84:640,1994. (4) I. Sako et al. Ann. Phytopathol. Soc. Jpn. 57:65, 1991.
First Report of Cercospora tripolitana Causing Leaf Spot of Emex spinosa in Tunisia
Authors: Kammoun L. G. , Souissi T.
Published: June 2009

Emex spinosa (L.) is a common weed in cereal crops and pastures in northern Tunisia. The build up of the seed bank from a cropping-grazing farming system makes chemical and cultural controls inefficient. Biological control as part of integrated weed management may improve weed control. Diseased seedlings were collected from several locations in northern Tunisia during field surveys. Symptoms were small, circular, light brown leaf spots varying in size (1.75 to 3.5 mm in diameter) with a definite dark brown border on both sides of leaves that wilted and died. Microscopic observations showed conidiophores and conidia within and around the spots. Pure cultures from single conidia were obtained on carrot leaf extract agar. The fungus was identified as Cercospora tripolitana on the basis of identification keys described by Chupp (1). Conidia, borne on unbranched, fasciculated conidiophores, were elongate, hyaline, multiseptate, 110 to 150 × 1.8 to 3.7 μm (average 130 to 2.5 μm), and had truncate bases. For pathogenicity testing, six plants were sprayed with a spore suspension of 6 × 105 conidia/ml. Controls were sprayed with sterile distilled water. Plants were placed in a growth chamber at 22°C, 95% relative humidity, and 18/6 h of light/dark and monitored for symptoms. Ten days after inoculation, symptoms identical to those observed in the field were observed on inoculated plants. Control plants did not develop any symptoms. Four weeks later, diseased leaves turned yellow and died. The fungus was reisolated from symptomatic plants according to Koch's postulates. Although C. tripolitana has been previously reported in North and South Africa, to our knowledge, this is the first report of the fungus as a pathogen on E. spinosa under Tunisian agroecological conditions, making it a promising candidate for weed control.

Reference: (1) C. Chupp. A Monograph of the Fungus Genus Cercospora. C. Chupp, Ithaca, New York, 1953.
First Report of Verticillium dahliae on Squash (Cucurbita pepo) in Italy
Authors: Stravato V. M. , Carannante G. , Moretti C. , Cappelli C.
Published: June 2009

During field surveys in February and March of 2007 and 2008, unusual symptoms of wilting were observed on squash plants (Cucurbita pepo L.) cultivated near Fondi (Latium-Central Italy) in two commercial plastichouses. Because of the high incidence of the disease (between 20 and 30%), we performed specific diagnostic assays. Symptoms included yellowing, stunting, vascular discoloration, and premature death of leaves. A fungus was consistently isolated on potato dextrose agar (PDA) from discolored vascular tissues in the stems. On the basis of fungal morphology (one-celled conidia, 1 to 2 μm in diameter, and produced on verticillate conidiophores), the fungus was identified as Verticillium dahliae Kleb. (1). To verify the pathogenicity of three fungal isolates, 2-week-old seedlings (15 plants per isolate) were inoculated by dipping the roots in a suspension of 105 conidia per ml for 30 s. Inocula were obtained from 2-week-old fungal cultures grown on PDA at 20 ± 2°C. Roots of 15 control plants were dipped in water. The seedlings were transplanted into pots containing peat and river sand (1:1, v/v) and placed in a greenhouse at 20 to 25°C. One month after inoculation, all fungal isolates caused wilting, while no symptoms were observed on control plants. The morphological features of the reisolated fungus, obtained only from the inoculated plants, were identical to the original isolates. V. dahliae has been recorded in Italy on a number of other plants (1,2). To our knowledge, this is the first report of V. dahliae on squash in Italy. Recently, V. dahliae was recorded for the first time on C. pepo L. in Trinidad (3).

References: (1) M. Cirulli. L'Italia Agricola 112:120, 1975. (2) A. Matta et al. Inf. Fitopatol. 30:5, 1980. (3) S. N. Rampersad. Plant Dis. 92:1136, 2008.
First Report of Root Rot and Twigs Wilting of Olive Trees in Argentina Caused by Phytophthora nicotianae
Authors: Vettraino A. M. , Lucero G. , Pizzuolo P. , Franceschini S. , Vannini A.
Published: June 2009

In Argentina, olives (Olea europaea) are planted on approximately 90,000 ha located primarily in the northwest continental regions. During a 2005 survey, root rot was recorded at several olive plantations in Catamarca, La Rioja, and San Juan provinces (3). Aboveground symptoms associated with root rot were twigs wilting with or without chlorosis, defoliation, and death. Symptoms were initiated on lateral branches and sometimes affected the entire crown. Even if young (5-year-old) trees displayed root rot, aerial symptoms may or may not be seen until years later. Disease incidence varied from 3 to 30%. Rotted rootlets were associated mainly with the infection of Phytophthora palmivora Butler and less frequently with another Phytophthora species. Isolates of this species were heterothallic, had a fluffy growth on carrot agar, and arachnoid growth on potato dextrose agar. Chlamydospores approximately 36 μm in diameter were also produced. The species developed prominent, papillate, noncaducous sporangia of different shapes ranging from ellipsoid to spherical when submerged in saline solution. Sporangia were 35 to 57 × 25 to 45 μm (average 44 × 33 μm), L:B ratio from 1.1 to 1.7. Isolates formed oogonia and amphyginous antheridia following mating type assays. On the basis of morphological features, these isolates were identified as P. nicotianae Breda de Haan. Identity was confirmed by sequencing the rDNA internal transcribed spacer (GenBank Accession No. FJ746693) (1). One-year-old O. europea seedlings were challenged with P. nicotianae (A1 isolates 306G and 339) through soil infestation assay in a growth chamber at 25°C. Infested and uninfested autoclaved millet grains moistened with V8 juice were used to inoculate 15 olive seedlings per isolate and controls, respectively. Fifty days after inoculation, seedlings showed foliar symptoms similar to those observed in the field and had an average of 50% reduction in the root system. Control plants remained healthy. P. nicotianae was always reisolated from symptomatic roots. P. nicotianae was reported on Citrus aurantium in Argentina in 1947 and is currently associated with several hosts (2). In 2002, the same species was reported associated with olive root rot in southern Italy (4). It is possible that P. nicotianae was recently introduced into Argentina through importation of Mediterranean olive varieties. The demonstrated pathogenicity of P. nicotianae on olive together with the recently reported detection of P. palmivora (3) presents a serious threat to olive cultivation in Argentina.

References: (1) D. E. L. Cooke et al. Fungal Genet. Biol. 30:17, 2000. (2) M. J. Frezzi. Rev. Investig. Agric. 4:47, 1950. (3) G. Lucero et al. Plant Pathol. 56:728, 2007. (4) F. Nigro and A. Ippolito. Acta Hortic. 586:777, 2002.
First Report of Grape Root Rot Caused by Roesleria subterranea in Michigan
Authors: Miles T. D. , Schilder A. M. C.
Published: June 2009

In September of 2008, declining grapevines were observed in two vineyards (Vitis interspecific hybrids ‘Canada Muscat’ and ‘Chardonel’) in Fennville, MI. Affected vines were stunted with shortened internodes and yellow leaves; others had dead cordons or were entirely dead. The grower reported that vines were losing vigor and collapsing during a period of 2 years. Renewal trunks would collapse during the second season of growth. Several symptomatic vines showed signs of root decay. On one vine, distinctive fruiting bodies (mazaedia) were apparent on the roots below the soil line and resembled those of Roesleria subterranea (Weinm.) Redhead (2,3,4). The mazaedia were 4 to 5 mm tall and 1 mm in diameter with white-to-tan stipes and powdery, gray-to-greenish hemispherical heads. Ascospores were hyaline to light grayish green, disk shaped, and 4 to 6 μm in diameter. This fungus, also known as R. hypogaea Thüm & Pass., has been previously reported to cause grape root rot, vine decline, and replant problems in North America and Europe (2,3,4). The fungus was cultured from ascospores on potato dextrose agar (PDA). Colonies grew slowly (approximately 2 mm per day at 22 to 24°C) and were green in the center. No spores were produced. DNA was extracted, and internal transcribed spacer (ITS) sequences obtained by PCR were compared with known sequences using BLASTn (1). Our isolate had 100% ITS sequence homology to an isolate from Germany, Roesleria subterranea strain IB (Accession No. EF060304.1). To test for pathogenicity, the fungus was grown in potato dextrose broth for 14 days at 22 to 24°C. An aqueous suspension (0.1 g of fungus per ml) was prepared by blending mycelia with sterile deionized water (SDW) in a food processor. Five two-node, rooted ‘Chardonnay’ cuttings (45 days old) were placed in the suspension. Five other cuttings were placed in SDW (control). After 3 h, plants were removed and repotted in fresh BACTO soil (Michigan Peat Company, Houston, TX) and kept in a growth chamber at 23°C with a 16/8-h light/dark cycle. After 25 days, inoculated plants were, on average, 63% smaller with 77% lower fresh-root weight and fewer fine roots than the control plants. The pathogen was recovered from surface-disinfested roots of all five inoculated plants but not from the control plants. Cultures appeared similar to the original isolate and their identity was confirmed by ITS sequencing. To our knowledge, this is the first report of R. subterranea on grapes in Michigan and the Midwest. This fungus needs to be recognized as a potential cause of vine decline and replant problems in Midwestern vineyards.

References: (1) S. F. Altschul et al. J. Mol. Biol. 215:403, 1990. (2) W. Gärtel. Page 40 in: Compendium of Grape Diseases. R. C. Pearson and A. C. Goheen, eds. The American Phytopathological Society, St. Paul, MN, 1988. (3) M. Kirchmair et al. Mycol. Res. 112:1210, 2009. (4) J. R. Liberato et al. Pest and Diseases Image Library. Online publication, 2009.
Epithelial Functions of the Residual Bowel After Surgery for Necrotising Enterocolitis in Human Infants
Authors: Schaart Maaike W , de Bruijn Adrianus CJM , Bouwman Deirdre M , de Krijger Ronald R , van Goudoever Johannes B , Tibboel Dick , Renes Ingrid B
Published: June 2009

Objectives:

Information on epithelial functions of the residual small or colonic bowel after resection for necrotising enterocolitis (NEC) in human infants is scarce. Our aim is to evaluate epithelial functions in the intestinal resection margins of tissue obtained at bowel resection for acute NEC and consecutive stoma closure.

Materials and Methods:

Epithelial morphology, proliferation, and protein expression were (immuno)histochemically studied.

Results:

Acute NEC was associated with severe and mild epithelial damage varying from epithelial loss to fairly unaffected epithelium. Epithelial proliferation was increased both at acute NEC and at stoma closure. In acute NEC, lactase, glucose transporter‐2 and ‐5 expression was down‐regulated in severely affected epithelium, whereas sucrase‐isomaltase and intestinal fatty acid binding protein expression was maintained. Goblet cells continued to express mucin 2 and trefoil factor 3, however, their numbers were decreased. Moreover, in acute NEC, Paneth cells were weakly lysozyme positive and were reduced in number. At stoma closure, expression of the above cell type–specific markers had completely been re‐established.

Conclusions:

Residual bowel after resection for acute NEC shows a disturbed epithelial proliferation/differentiation balance. Acute NEC was associated with downregulation of distinct enterocyte‐specific proteins. Because of goblet cell and Paneth cell loss in acute NEC, mucosal barrier, and defense functions may be impaired.
Rapid Infliximab Infusions in Pediatric Inflammatory Bowel Disease
Authors: Yeckes Alyson R , Hoffenberg Edward J
Published: June 2009

The manufacturer of infliximab recommends infusion over 2 to 3 hours. In 16 children who received 133 standard 2‐ to 3‐hour infusions, followed by fifty 1‐hour infusions, chart review revealed a frequency of infusion reactions of 2% with both infusion protocols (3/133 and 1/50). The first reaction with the rapid infusion occurred in a patient who had experienced an identical reaction with the longer infusion, but was mistakenly not premedicated. Our data suggest rapid infusion over 1 hour in selected pediatric patients is safe and cost‐effective. Compared with reported adult data, our data suggest similar or lower frequency of adverse events.