bluuebunny/crossref_metadata_2025 huggingface dataset:
Atomistic simulation of damage production by atomic and molecular ion irradiation in GaN
Authors: Ullah M. W. , Kuronen A. , Nordlund K. , Djurabekova F. , Karaseov P. A. , Titov A. I.
Published: August 2012

We have studied defect production during single atomic and molecular ion irradiation having an energy of 50 eV/amu in GaN by molecular dynamics simulations. Enhanced defect recombination is found in GaN, in accordance with experimental data. Instantaneous damage shows non-linearity with different molecular projectile and increasing molecular mass. Number of instantaneous defects produced by the PF4 molecule close to target surface is four times higher than that for PF2 molecule and three times higher than that calculated as a sum of the damage produced by one P and four F ion irradiation (P+4×F). We explain this non-linearity by energy spike due to molecular effects. On the contrary, final damage created by PF4 and PF2 shows a linear pattern when the sample cools down. Total numbers of defects produced by Ag and PF4 having similar atomic masses are comparable. However, defect-depth distributions produced by these species are quite different, also indicating molecular effect.
Controlling the resistivity gradient in aluminum-doped zinc oxide grown by plasma-enhanced chemical vapor deposition
Authors: Ponomarev M. V. , Verheijen M. A. , Keuning W. , van de Sanden M. C. M. , Creatore M.
Published: August 2012

Aluminum-doped ZnO (ZnO:Al) grown by chemical vapor deposition (CVD) generally exhibit a major drawback, i.e., a gradient in resistivity extending over a large range of film thickness. The present contribution addresses the plasma-enhanced CVD deposition of ZnO:Al layers by focusing on the control of the resistivity gradient and providing the solution towards thin (≤300 nm) ZnO:Al layers, exhibiting a resistivity value as low as 4 × 10−4 Ω cm. The approach chosen in this work is to enable the development of several ZnO:Al crystal orientations at the initial stages of the CVD-growth, which allow the formation of a densely packed structure exhibiting a grain size of 60–80 nm for a film thickness of 95 nm. By providing an insight into the growth of ZnO:Al layers, the present study allows exploring their application into several solar cell technologies.
Effects of interfacial bonding in the Si-carbon nanotube nanocomposite: A molecular dynamics approach
Authors: Kim Byung-Hyun , Lee Kwang-Ryeol , Chung Yong-Chae , Gunn Lee June
Published: August 2012

We investigated the effects of interfacial bonding on the mechanical properties in the Si-carbon nanotube (CNT) nanocomposite by a molecular dynamics approach. To describe the system appropriately, we used a hybrid potential that includes Tersoff, AIREBO (adaptive intermolecular reactive empirical bond order), and Lennard–Jones potentials. With increasing bonding strength at the interface of Si matrix and CNT, toughness as well as Young’s modulus and maximum strength increased steadily. CNT pull-out and load transfer on the strong CNT were identified as the main mechanisms for the enhanced properties. At optimum bonding, crack tip was deflected around CNT and the fracture proceeded in plastic mode through Si matrix owing to the strong reinforcement of CNT, and resulted in a further enhancement of toughness. At maximum bonding, however, only load transfer is operative and the fracture returned to brittle mode. We concluded that a strong interface as long as the CNT maintains its structural integrity is desirable to realize the optimum result.
Amplification of hippersound in graphene under external direct current electric field
Authors: Nunes O. A. C. , Fonseca A. L. A.
Published: August 2012

We present a theoretical investigation on the hippersound generation and amplification in n-type graphene in the presence of a dc driving electric field. By investigating the consequences of electron-acoustic phonon interaction in a gated graphene, we have found the conditions for phonon amplification to be obtained, namely vD>ṽs,vD being the drift velocity of electrons in the dc field and and ṽs being the effective sound velocity in the graphene sheet and Rq→>Γq→, where Rq→ is the phonon generation rate and Γq→ is the phonon linear losses. By considering two extreme values of the electron mobility in graphene, namely μ = 20 000 cm2/Vs and 1.2 V/cm for μ = 190 000 cm2/Vs, the critical external electric fields for hippersound amplification were obtained as much as 10 V/cm 1.2 V/cm, respectively. These threshold dc fields are smaller when compared with the corresponding applied fields for phonon amplification in semiconducting bulk and nanostructures. The study is relevant to the application of graphene as acoustoelectric devices as well as in the construction of a high-frequency phonon spectrometer.
Propagating surface plasmon resonances in two-dimensional patterned gold-grating templates and surface enhanced Raman scattering
Authors: Mandal P. , Nandi A. , Ramakrishna S. Anantha
Published: August 2012

Surface enhanced Raman scattering (SERS) from Raman active rhodamine-6G probe molecules is investigated on two-dimensional patterned gold-grating templates having submicron periodicity of 800 nm. Two-dimensional surface nano-patterning in the form of square, hexagonal, and rectangle has been obtained through cost effective laser interference lithography. We find a reproducible SERS enhancement of the order of 105 on these nano-patterned plasmonic templates, showing a slight superior result on hexagonal patterned templates. Strong localized near-fields due to surface plasmon resonance (SPR) lead to such an enhancement. We find evidence for good correlation in the SPR excitation and enhanced Raman scattering through experimental investigation by using different Raman pump excitation wavelengths of 785 nm, 633 nm, and 514 nm and different pump powers. The results are strongly supported by computer simulations of the electromagnetic fields at the pump wavelengths. Our results demonstrate that an optimized selection of the structure and pump excitation wavelength is necessary for good SERS signal.
Global stability analysis of discrete-time coupled systems on networks and its applications
Authors: Su Huan , Li Wenxue , Wang Ke
Published: August 2012

This paper is concerned with the global stability for a general discrete-time coupled system on network (DTCSN). A systematic method of constructing global Lyapunov function for the DTCSN is provided by combining graph theory and the Lyapunov method. Consequently, some novel global stability principles, which have close relation to the topology property of the network, are given. They have important leading significance in the design and applications for the globally stable DTCSNs. In addition, to present the effectiveness and applicability of the results, the proposed theory is used to analyze the global stability for some practical models and numerical methods.
Source-Finding for the Australian Square Kilometre Array Pathfinder
Authors: Whiting M. , Humphreys B.
Published: August 2012

The Australian Square Kilometre Array Pathfinder (ASKAP) presents a number of challenges in the area of source finding and cataloguing. The data rates and image sizes are very large, and require automated processing in a high-performance computing environment. This requires development of new tools, that are able to operate in such an environment and can reliably handle large datasets. These tools must also be able to accommodate the different types of observations ASKAP will make: continuum imaging, spectral-line imaging, transient imaging. The ASKAP project has developed a source-finder known as selavy, built upon the duchamp source-finder. selavy incorporates a number of new features, which we describe here.

Since distributed processing of large images and cubes will be essential, we describe the algorithms used to distribute the data, find an appropriate threshold and search to that threshold and form the final source catalogue. We describe the algorithm used to define a varying threshold that responds to the local, rather than global, noise conditions, and provide examples of its use. And we discuss the approach used to apply two-dimensional fits to detected sources, enabling more accurate parameterisation. These new features are compared for timing performance, where we show that their impact on the pipeline processing will be small, providing room for enhanced algorithms.

We also discuss the development process for ASKAP source finding software. By the time of ASKAP operations, the ASKAP science community, through the Survey Science Projects, will have contributed important elements of the source finding pipeline, and the mechanisms in which this will be done are presented.
One-Pot, Three-Step Reaction of 5-[(Trimethylsilyl)ethynyl]pyrrolidin-2-one with Azides Catalyzed by CuI: Synthesis of a Novel Class of 1,4-Disubstituted 1,2,3-Triazoles
Authors: Stefani Hélio A. , Ferreira Fernando P. , Vieira Adriano S.
Published: August 2012

A very fast, easy and efficient synthesis is described for a novel and biologically important class of 1,4-disubstituted-4-(5-pyrrolidin-2-one)-1,2,3-triazoles by an ultrasound-assisted one-pot, three-step click reaction sequence of 5-[(trimethylsilyl)ethynyl]pyrrolidin-2-one with organic azides mediated by catalytic CuI salts.
Diffusive racetrack oxidation in a Ti sputter target by reactive high power impulse magnetron sputtering
Authors: Audronis M , Abrasonis G , Munnik F , Heller R , Chapon P , Bellido-Gonzalez V
Published: August 2012

This paper reports experimental results for near-surface Ti sputter target oxidation in a magnetron racetrack during reactive high power impulse magnetron sputtering (HIPIMS) at various optical plasma monitoring set-points in the transition region between ‘metal’ and ‘poisoned’ target states. Oxygen depth profiles were obtained by nuclear reaction analysis and glow discharge optical emission spectroscopy. Ti target surface oxidation depth as induced by reactive HIPIMS was found to depend on the process set-point as well as discharge conditions. Deepest oxidation was observed when operating close to ‘fully poisoned (FP)’ or in ‘FP’ regime with oxygen profiles extending as deep as ∼0.5 µm (oxygen concentration ⩾5 at%). Oxygen profiles obtained indicate the occurrence of oxygen bulk diffusion. Process induced elevated target surface temperature, magnetic field and plasma assistance are suggested to contribute substantially to these profiles. Based on these findings it is proposed that ion-bombardment-assisted thermal diffusion is a third target poisoning mechanism that can be taking place and is therefore important in reactive HIPIMS in addition to the two currently accepted mechanisms—ion implantation and chemisorption. Under the conditions investigated in this work, diffusive oxidation was most significant when operating in the lower part of the hysteresis loop. Reactive HIPIMS processes that will facilitate significant diffusive sputter target surface oxidation will also be expected to exhibit wider hysteresis and longer target cleaning times after substantial target poisoning.
Nonvolatile bipolar resistive switching in an Ag/TiO2/Nb : SrTiO3/In device
Authors: Zhu Yongdan , Li Meiya , Zhou Hai , Hu Zhongqiang , Liu Xiaolian , Fang Xiaoli , Sebo Bobby , Fang Guojia , Zhao Xingzhong
Published: August 2012

A TiO2 thin film was deposited on a Nb : SrTiO3 substrate by pulsed laser deposition to form an Ag/TiO2/Nb : SrTiO3/In device. The bipolar resistive switching (RS) effect of this device was investigated. The current–voltage characteristics exhibited pronounced and stable bipolar RS features. The device could be switched to a low resistance state (LRS) at forward voltage and returned to a high resistance state (HRS) at reverse voltage, and the RS ratio R
HRS/R
LRS reached up to 2 × 103 at a read voltage of −0.5 V. Moreover, the RS ratio could be adjusted by changing the maximum value of the forward or reverse voltage, which shows promise for multilevel memories. These results are discussed by considering carrier injection-trapped/detrapped process of the heterostructure and show high potential for nonvolatile memory applications.
Synthesis of an embedded metal nanoparticle planar assembly by low-energy ion irradiation of a thin discontinuous metal film sandwiched in silica
Authors: Khan Saif A , Srivastava S K , Avasthi D K
Published: August 2012

Synthesis of a planar assembly of metal nanoparticles embedded in silica by low-energy ion irradiation is presented here. Argon ions of 350 keV were used to irradiate SiO2/Au/SiO2 and SiO2/Ag/SiO2 tri-layered films, with oxide thicknesses of 40 nm and metal layer thickness of 2 nm, to synthesize well isolated nanoparticles without the need of annealing. The nanoparticles have an average diameter of about 6 nm as revealed by transmission electron microscopy. Simulations by three-dimensional kinetic lattice Monte Carlo were performed to understand the ion-induced nanoparticle array formation from the initially percolated as-deposited metal layer embedded in the silica matrix.
The Tom40 assembly process probed using the attachment of different intramitochondrial sorting signals
Authors: Shiota Takuya , Maruyama Miyuki , Miura Mami , Tamura Yasushi , Yamano Koji , Esaki Masatoshi , Endo Toshiya
Published: August 2012

The TOM40 complex is a protein translocator in the mitochondrial outer membrane and consists of several different subunits. Among them, Tom40 is a central subunit that constitutes a protein-conducting channel by forming a β-barrel structure. To probe the nature of the assembly process of Tom40 in the outer membrane, we attached various mitochondrial presequences to Tom40 that possess sorting information for the intermembrane space (IMS), inner membrane, and matrix and would compete with the inherent Tom40 assembly process. We analyzed the mitochondrial import of those fusion proteins in vitro. Tom40 crossed the outer membrane and/or inner membrane even in the presence of various sorting signals. N-terminal anchorage of the attached presequence to the inner membrane did not prevent Tom40 from associating with the TOB/SAM complex, although it impaired its efficient release from the TOB complex in vitro but not in vivo. The IMS or matrix-targeting presequence attached to Tom40 was effective in substituting for the requirement for small Tim proteins in the IMS for the translocation of Tom40 across the outer membrane. These results provide insight into the mechanism responsible for the precise delivery of β-barrel proteins to the outer mitochondrial membrane.
Nucleolar AATF regulates c-Jun–mediated apoptosis
Authors: Ferraris Saima E. , Isoniemi Kimmo , Torvaldson Elin , Anckar Julius , Westermarck Jukka , Eriksson John E.
Published: August 2012

The AP-1 transcription factor c-Jun has been shown to be essential for stress-induced apoptosis in several models. However, the molecular mechanisms underlying the proapoptotic activity of c-Jun are poorly understood. We identify the apoptosis-antagonizing transcription factor (AATF) as a novel nucleolar stress sensor, which is required as a cofactor for c-Jun–mediated apoptosis. Overexpression or down-regulation of AATF expression levels led to a respective increase or decrease in the amount of activated and phosphorylated c-Jun with a proportional alteration in the induction levels of the proapoptotic c-Jun target genes FasL and TNF-α. Accordingly, AATF promoted commitment of ultraviolet (UV)-irradiated cells to c-Jun-dependent apoptosis. Whereas AATF overexpression potentiated UV-induced apoptosis in wild-type cells, c-Jun–deficient mouse embryonic fibroblasts were resistant to AATF-mediated apoptosis induction. Furthermore, AATF mutants defective in c-Jun binding were also defective in inducing AP-1 activity and c-Jun–mediated apoptosis. UV irradiation induced a translocation of AATF from the nucleolus to the nucleus, thereby enabling its physical association to c-Jun. Analysis of AATF deletion mutants revealed that the AATF domains required for compartmentalization, c-Jun binding, and enhancement of c-Jun transcriptional activity were all also required to induce c-Jun–dependent apoptosis. These results identify AATF as a nucleolar-confined c-Jun cofactor whose expression levels and spatial distribution determine the stress-induced activity of c-Jun and the levels of c-Jun–mediated apoptosis.
Biologistics—Diffusion coefficients for complete proteome of Escherichia coli
Authors: Kalwarczyk Tomasz , Tabaka Marcin , Holyst Robert
Published: September 2012

Motivation: Biologistics provides data for quantitative analysis of transport (diffusion) processes and their spatio-temporal correlations in cells. Mobility of proteins is one of the few parameters necessary to describe reaction rates for gene regulation. Although understanding of diffusion-limited biochemical reactions in vivo requires mobility data for the largest possible number of proteins in their native forms, currently, there is no database that would contain the complete information about the diffusion coefficients (DCs) of proteins in a given cell type.

Results: We demonstrate a method for the determination of in vivo DCs for any molecule—regardless of its molecular weight, size and structure—in any type of cell. We exemplify the method with the database of in vivo DC for all proteins (4302 records) from the proteome of K12 strain of Escherichia coli, together with examples of DC of amino acids, sugars, RNA and DNA. The database follows from the scale-dependent viscosity reference curve (sdVRC). Construction of sdVRC for prokaryotic or eukaryotic cell requires ~20 in vivo measurements using techniques such as fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), nuclear magnetic resonance (NMR) or particle tracking. The shape of the sdVRC would be different for each organism, but the mathematical form of the curve remains the same. The presented method has a high predictive power, as the measurements of DCs of several inert, properly chosen probes in a single cell type allows to determine the DCs of thousands of proteins. Additionally, obtained mobility data allow quantitative study of biochemical interactions in vivo.

Contact:  rholyst@ichf.edu.pl

Supplementary information:  Supplementary data are available at Bioinformatics Online.
LAC2 Encoding a Secreted Laccase Is Involved in Appressorial Melanization and Conidial Pigmentation in Colletotrichum orbiculare
Authors: Lin Shao Yu , Okuda Shiho , Ikeda Kyoko , Okuno Tetsuro , Takano Yoshitaka
Published: August 2012

Both Colletotrichum and Magnaporthe spp. develop appressoria pigmented with melanin, which is essential for fungal pathogenicity. 1,8-Dihydroxynaphthalene (1,8-DHN) is believed to be polymerized to yield melanin around the appresorial cell wall through the oxidative activity of laccases. However, no 1,8-DHN laccase has yet been identified in either Colletotrichum or Magnaporthe spp. Here, we report a laccase gene, LAC2, that is involved in the appressorial melanization of Colletotrichum orbiculare, which causes cucumber anthracnose. LAC2 encodes a protein with a signal peptide and has high homology to fungal laccases. The conidial color of lac2 mutants is distinct from that of the C. orbiculare wild type, and the mutants are nonpathogenic. Notably, the mutant appressoria are defective in melanization, and a host invasion assay showed that the appressoria are nonfunctional. LAC2 was induced during appressorial melanization. These results suggest that LAC2 oxidizes 1,8-DHN in the appressoria. The LAC2 homologues of other fungi located in the same phylogenetic clade as LAC2 fully complemented the lac2 mutants. Interestingly, a LAC2 homologue, located in a different clade, complemented the conidial pigmentation but not appressorial melanization of the mutants, suggesting that the LAC2 function in appressorial melanization might only be conserved in laccases of the LAC2 clade.
Differential Effect of SdhB Gene Mutations on the Sensitivity to SDHI Fungicides in Botrytis cinerea
Authors: Veloukas Thomas , Markoglou Anastasios N. , Karaoglanidis George S.
Published: August 2012

Succinate dehydrogenase inhibiting (SDHI) fungicides constitute a relatively novel fungicide group used for gray mold control caused mainly by Botrytis cinerea. Shortly after registration, resistance was observed in fungal populations that correlated with several mutations in the succinate dehydrogenase complex (complex II). In the current study, 30 B. cinerea isolates possessing five different mutations at three different codons of SdhB (P225F, N230I, and H272L/R/Y) were characterized for their sensitivities to eight SDHI fungicides. The results show different sensitivities and cross-resistance patterns between structurally different SDHIs. P225F mutants were resistant in vitro to all SDHIs tested. Similarly, isolates possessing the H272L mutation were highly resistant to boscalid but showed low to moderate levels of resistance to other SDHIs. The N230I mutants were moderately resistant to boscalid, fluopyram, and fluxapyroxad and showed low resistance levels to isopyrazam, bixafen, fenfuram, benodanil, and carboxin. The H272R mutants showed moderate levels of resistance to boscalid and low resistance levels to isopyrazam, fenfuram, and carboxin but remained sensitive to fluopyram, bixafen, fluxapyroxad, and benodanil. Similarly, the H272Y showed moderate levels of resistance to boscalid and very low resistance levels to isopyrazam, bixafen, fenfuram, and carboxin but showed increased sensitivity to benodanil and fluopyram. Boscalid provided moderate to high control of H272R/Y and N230I mutants in detached fruit assays but provided little control against the H272L and P225F mutants. In contrast, fluopyram controlled H272R/Y mutants and provided moderate levels of control toward H272L, N230I, and P225F mutants. Our findings suggest that sensitivity to SDHIs may vary greatly, dependent on the point mutation in the sdhb subunit.
Pathogenic Variation in the Pearl Millet Blast Pathogen Magnaporthe grisea and Identification of Resistance to Diverse Pathotypes
Authors: Sharma Rajan , Upadhyaya H. D. , Manjunatha S. V. , Rai K. N. , Gupta S. K. , Thakur R. P.
Published: August 2012

Blast, also known as leaf spot, caused by Pyricularia grisea (teleomorph: Magnaporthe grisea), has emerged as a serious disease affecting both forage and grain production in pearl millet in India. Pathogenic variation was studied in a greenhouse using 25 M. grisea isolates collected from four major pearl-millet-growing states in India (Rajasthan, Haryana, Maharashtra, and Uttar Pradesh) on 10 pearl millet genotypes (ICMB 02444, ICMB 02777, ICMB 06444, ICMB 93333, ICMB 96666, ICMB 97222, ICMB 99444, 863B, ICMR 06222, and ICMB 95444). Differential reactions to the test isolates were recorded on ICMB 02444, ICMB 93333, ICMB 97222, 863B, and ICMR 06222. The 25 isolates were grouped into five different pathotypes based on their reaction types (virulent = score ≥ 4 and avirulent = score ≤ 3 on a 1-to-9 scale). For the identification of resistance sources, a pearl millet mini-core comprising 238 accessions was evaluated under greenhouse conditions against five M. grisea isolates (Pg118, Pg119, Pg56, Pg53, and Pg45) representing the five pathotypes. Of 238 accessions, 32 were found to be resistant to at least one pathotype. Resistance to multiple pathotypes (two or more) was recorded in several accessions, while three accessions (IP 7846, IP 11036, and IP 21187) exhibited resistance to four of the five pathotypes. Four early-flowering (≤50 days) blast-resistant mini-core accessions (IP 7846, IP 4291, IP 15256, and IP 22449) and four accessions (IP 5964, IP 11010, IP 13636, and IP 20577) having high scores (≥7) for grain and green fodder yield potential and overall plant aspect were found to be promising for utilization in pearl millet improvement programs. Identification of five pathotypes of M. grisea and sources of resistance to these pathotypes will provide a foundation for breeding for blast resistance in pearl millet in India.
First Report of Pestalotiopsis clavispora Causing Leaf Spot of Carya illinoensis in Brazil
Authors: Lazarotto M. , Muniz M. F. B. , Poletto T. , Dutra C. B. , Blume E. , Harakawa R. , Poletto I.
Published: August 2012

Conspicuous leaf spots in combination with fruit spots were observed for the first time in April and May 2010 on a 30-ha pecan [Carya illinoensis (Wangenh.) K. Koch] orchard in the state of Rio Grande do Sul, Brazil. Initially, tiny grey spots were observed on leaves and, over time, the spots expanded to become gray to light brown circles surrounded by a dark brown border, followed by leaves falling. Eventually, fruits were also attacked, with typical symptoms beginning with tiny water soaked spots which then became necrotic. The disease was also observed in pecan nursery and field seedlings. Isolation of the pathogen from symptomatic leaves and morphological identification by conidia characters (number of cells, color, hyaline terminal cells, number of appendages) revealed Pestalotiopsis sp. (2) as the causal agent of the disease. Conidia constituted of transverse septa with four dark intermediate sections and two hyaline terminal sections. One of the terminal sections presented two or three apical appendages. Conidia averaged 6.88 μm wide × 31.00 μm long, not considering the apical appendages. Primers ITS 1 and ITS 4 were used to amplify the internal transcribes spacer ITS 1-5.8S-ITS 2 region. Nucleotide sequences were 99% similar to Pestalotiopsis clavispora (G.F. Atk.) Steyaert. Conidia produced on potato dextrose agar medium were used to inoculate 8 plants with a spore suspension of 2.0 × 106 conidia/ml. Eight additional plants were used as control (non-inoculated). The inoculation was performed by spraying the suspension onto the leaves of Pecan seedlings and the plants were incubated for 72 h in a humid chamber (1). All inoculated plants showed symptoms 25 days after inoculation and the fungus was reisolated. The pathogenicity test was repeated once. Ten more isolates collected from four different cities in the same state were identified as Pestalotiopsis spp. by morphological characterization and pathogenicity was confirmed. Because this disease causes losses on production of nuts indirectly by reducing photosynthetically active area when the pathogen attacks leaves and directly when attacking fruits, it may restrict the production where the pathogen occurs. On some orchards in the state of Rio Grande do Sul, the attack rate reached 80% of the plants. P. clavispora has been reported causing stem end-rot of avocado in Chile (3), but this note constitutes the first report, to our knowledge, of P. clavispora causing leaf spot on C. illinoensis in Brazil.

References: (1) A. C. Alfenas and F. A. Ferreira. Page 117 in: Métodos em Fitopatologia. A. C Alfenas and R. G. Mafia (eds.). Editora: UFV, Viçosa, 2007. (2) S. S. N. Maharachchikumbura et al. Fungal Diversity 50:167, 2011. (3) A. L. Valencia et al. Plant Dis. 95:492, 2011.
High Potassium, Calcium, and Nitrogen Application Reduce Susceptibility to Banana Xanthomonas Wilt Caused by Xanthomonas campestris pv. musacearum
Authors: Atim Margaret , Beed Fen , Tusiime Geoffrey , Tripathi Leena , van Asten Piet
Published: August 2012

The effect of exogenous applications of potassium (K), calcium (Ca), and nitrogen (N) on the susceptibility of four banana cultivars to Banana Xanthomonas wilt (BXW) was studied. Murashige and Skoog (MS) medium with normal concentrations of K at 783 mg/liter, Ca at 121 mg/liter, and N at 841 mg/liter was modified to contain various concentrations of K, Ca, and N. Each nutrient was varied singly, each with three replicate experiments. The concentrations were K at 78, 157, 391, 783, 1,565, and 3,913 mg/liter; Ca at 12, 24, 60, 121, 241, and 603 mg/liter; and N at 84, 168, 420, 841, and 1,682 mg/liter. Plantlets were generated in vitro on normal MS medium and later exposed to the nutrient concentrations for a total of 8 weeks. Thereafter, they were artificially inoculated with Xanthomonas campestris pv. musacearum using an insulin syringe. In each nutrient, plantlets exposed to higher nutrient concentrations significantly (P < 0.0001) accumulated more nutrient in their tissues compared with those exposed to lesser nutrient concentrations. Wilt incidences were significantly reduced, and incubation periods (time from inoculation to appearance of first disease symptoms) increased, with increasing nutrient application. The study lays a background for in vivo studies aimed at management of BXW using nutrients, such as fertilizer application.
First Report of Botryosphaeria dothidea Causing Fruit Rot of Plum in Spain
Authors: Roca L. F. , Raya M. C. , Trapero A.
Published: August 2012

Species in the Botryosphaeriaceae are known to produce cankers, dieback, blights, and leaf spots on many hosts, mainly under stress conditions. Several Botryosphaeria spp. may also cause pre- or post-harvest decay of stone fruit, such as peaches (2). In June 2012, fruit of plum (Prunus domestica cv. Golden Japan) showing soft, brown, and slightly sunken necrotic lesions were observed in several orchards affected by hail in Cordoba province (southern Spain). Symptomatic fruit were collected and incubated at 25°C and 100% relative humidity. Isolations were done on potato dextrose agar (PDA). Mycelium and black pycnidia developed on the surface of incubated fruit and on PDA plates. Conidia were hyaline, aseptate, and fusoid. According to morphological criteria, the fungus was identified as Fusicoccum aesculi, the anamorph of Botryosphaeria dothidea (3). The internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS4/ITS5 and sequenced. BLAST analysis of the 528-bp fragment showed 100% homology with the sequence of B. dothidea. Pathogenicity tests were performed on immature healthy fruit (2 weeks before harvest) of the same cultivar from the same orchards. Fruit were washed in deionized water with Tween 20 (Polyoxyethylene 20 sorbitan monolaureate 99%, 0.1 ml/liter) and surface sterilized in 10% sodium hypochlorite for 1 min. Twenty-four fruit were inoculated using mycelial-agar discs. Twelve fruit were previously wounded with a sterile 0.5-mm-diameter needle. The same number of fruit, wounded and unwounded, served as a control. All fruit were incubated at 25°C and 100% relative humidity. Seven days after inoculation, 83% of wounded inoculated fruit showed rot symptoms. After 9 days, fruit rot symptoms started to appear on unwounded inoculated fruit. Twenty days after inoculation, 100% of wounded and unwounded fruit showed rot symptoms that led to mummification of the fruit. Pycnidia developed on inoculated fruit and the fungus was reisolated. No symptoms developed on control fruit. These results demonstrate that B. dothidea is pathogenic on plum and that wounds favor infection, although they are not needed. To our knowledge this is the first report of B. dothidea causing fruit rot of plum in Spain. This pathogen is well known in southern Spain causing a serious fruit rot of olive (1) and could have a great impact on plum production in this region, especially when there is damage to the fruits as occurred this year with hail.

References: (1) J. Moral et al. Phytopathology 100:1340, 2010. (2) J. M. Ogawa et al. Compendium of Stone Fruit Diseases. APS Press, St. Paul, MN, 1995. (3) B. Slippers et al. Mycologia 96:83, 2004.
Orbus sasakiae sp. nov., a bacterium isolated from the gut of the butterfly Sasakia charonda, and emended description of the genus

Orbus
Authors: Kim Joon Yong , Lee Jina , Shin Na-Ri , Yun Ji-Hyun , Whon Tae Woong , Kim Min-Soo , Jung Mi-Ja , Roh Seong Woon , Hyun Dong-Wook , Bae Jin-Woo
Published: September 2012

A novel Gram-stain-negative, facultatively anaerobic, non-motile and coccus-shaped bacterium, strain C7T, was isolated from the gut of the butterfly Sasakia charonda. Strain C7T grew optimally at 20–25 °C, at pH 7–8 and with 1 % (w/v) NaCl. The strain was negative for oxidase activity but positive for catalase activity. The 16S rRNA gene sequences of strain C7T and

Orbus hercynius

CN3T shared 96.8 % similarity. The major fatty acids identified were C14 : 0, C16 : 0, C18 : 1ω7c and summed feature 2 (comprising C14 : 0 3-OH/iso-C16 : 1). The major respiratory quinone was ubiquinone-8 (Q-8). The polar lipids of strain C7T were phosphatidylethanolamine, phosphatidylglycerol, an unidentified phospholipid and two unidentified aminophospholipids. The G+C content of the genomic DNA extracted from strain C7T was 32.1 mol%. Taken together, the phenotypic, genotypic and phylogenetic analyses indicate that strain C7T represents a novel species of the genus

Orbus

, for which the name Orbus sasakiae sp. nov. is proposed. The type strain is C7T ( = KACC 16544T = JCM 18050T). An emended description of the genus

Orbus

is provided.
Roseovarius sediminilitoris sp. nov., isolated from seashore sediment
Authors: Park Sooyeon , Yoon Jung-Hoon
Published: September 2012

A Gram-negative, motile and ovoid- to rod-shaped bacterial strain, designated M-M10T, was isolated from a seashore sediment collected from the South Sea, South Korea. Strain M-M10T grew optimally at pH 7.0–8.0, at 30 °C and in the presence of 2 % (w/v) NaCl. The phylogenetic trees based on 16S rRNA gene sequences revealed that strain M-M10T clustered with the type strains of

Roseovarius crassostreae

,

Roseovarius halocynthiae

and

Roseovarius marinus

, with which it exhibited sequence similarities of 97.4, 97.3 and 95.1 %, respectively. It exhibited 93.2–95.1 % sequence similarity to the type strains of the other species of the genus

Roseovarius

. Strain M-M10T contained Q-10 as the predominant ubiquinone and C18 : 1ω7c and C16 : 0 as the major fatty acids, as observed in the genus

Roseovarius

. The polar lipid profile of strain M-M10T was similar to that of

Roseovarius tolerans

DSM 11457T. The DNA G+C content of strain M-M10T was 63.0 mol% and its mean DNA–DNA relatedness values with

Roseovarius crassostreae

DSM 16950T and

Roseovarius halocynthiae

MA1-10T were 16 % and 22 %, respectively. Differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, demonstrated that strain M-M10T is distinct from other species of the genus

Roseovarius

. On the basis of the data presented, strain M-M10T is considered to represent a novel species of the genus

Roseovarius

, for which the name Roseovarius sediminilitoris sp. nov. is proposed. The type strain is M-M10T ( = KCTC 23959T = CCUG 62413T).
Serological cross-reactions between four polyomaviruses of birds using virus-like particles expressed in yeast
Authors: Zielonka Anja , Gedvilaite Alma , Reetz Jochen , Rösler Uwe , Müller Hermann , Johne Reimar
Published: August 2012

Polyomaviruses are aetiological agents of fatal acute diseases in various bird species. Genomic analysis revealed that avian polyomavirus (APyV), crow polyomavirus (CPyV), finch polyomavirus (FPyV) and goose hemorrhagic polyomavirus (GHPyV) are closely related to each other, but nevertheless form separate viral species; however, their serological relationship was previously unknown. As only APyV can be grown efficiently in tissue culture, virus-like particles (VLPs) were generated by expression of the genomic regions encoding the major structural protein VP1 of these viruses in yeast; these were used to elicit type-specific antibodies in rabbits and as antigens in serological reactions. For increased VLP assembly, a nuclear-localization signal was introduced into APyV-VP1. VLPs derived from the VP1 of the monkey polyomavirus simian virus 40 served as control. APyV-, GHPyV- and CPyV-VLPs showed haemagglutinating activity with chicken and human erythrocytes. CPyV- and GHPyV-specific sera showed slight cross-reactions in immunoblotting, haemagglutination-inhibition assay and indirect ELISA. The FPyV-specific serum inhibited the haemagglutination activity of APyV-VLPs slightly and showed a weak cross-neutralizing activity against APyV in cell-culture tests. Generally, these data indicate that the four polyomaviruses of birds are serologically distinct. However, in accordance with genetic data, a relationship between CPyV and GHPyV as well as between APyV and FPyV is evident, and grouping into two different serogroups may be suggested. The haemagglutinating activity of APyV, CPyV and GHPyV may indicate similar receptor-binding mechanisms for these viruses. Our data could be useful for the development of vaccines against the polyomavirus-induced diseases in birds and for interpretation of diagnostic test results.
Identification of a novel B-cell epitope of Hantaan virus glycoprotein recognized by neutralizing 3D8 monoclonal antibody
Authors: Yan Guolin , Zhang Yusi , Ma Ying , Yi Jing , Liu Bei , Xu Zhuwei , Zhang Yun , Zhang Chunmei , Zhang Fanglin , Xu Zhikai , Yang Angang , Zhuang Ran , Jin Boquan
Published: August 2012

Hantaan virus (HTNV), a member of the familyBunyaviridae, is a major agent causing haemorrhagic fever with renal syndrome, a high-mortality-rate disease threatening approximately 150 000 people around the world yearly. The 3D8 mAb displays a neutralizing activity to HTNV infection. In this study, the B-cell epitopes of HTNV glycoproteins (GPs) were finely mapped by peptide scanning. A new B-cell epitope882GFLCPEFPGSFRKKC896of HTNV, which locates on Gc, has been screened out from a set of 15-mer synthesized peptides covering the full-length of HTNV-GPs. It has been shown by the alanine-scanning technique that885C,893R,894K,895K and896C are the key amino acids of the binding sites of the GPs. The implications of identifying a novel B-cell epitope for hantavirus immunology and vaccinology are discussed.
Evolution of the human immunodeficiency virus type 1 protease: effects on viral replication capacity and protease robustness
Authors: Capel Elena , Martrus Glòria , Parera Mariona , Clotet Bonaventura , Martínez Miguel Angel
Published: August 2012

The rapid spread of human immunodeficiency virus type 1 (HIV-1) in humans has been accompanied by continuous extensive genetic diversification of the virus. The aim of this study was to investigate the impact of HIV-1 diversification on HIV-1 replication capacity (RC) and mutational robustness. Thirty-three HIV-1 protease sequences were amplified from three groups of viruses: two naïve sample groups isolated 15 years apart plus a third group of protease inhibitor-(PI) resistant samples. The amplified proteases were recombined with an HXB2 infectious clone and RC was determined in MT-4 cells. RC was also measured in these three groups after random mutagenesis in vitro using error-prone PCR. No significant RC differences were observed between recombinant viruses from either early or recent naïve isolates (P = 0.5729), even though the proteases from the recent isolates had significantly lower sequence conservation scores compared with a subtype B ancestral sequence (P<0.0001). Randomly mutated recombinant viruses from the three groups exhibited significantly lower RC values than the corresponding wild-type viruses (P<0.0001). There was no significant difference regarding viral infectivity reduction between viruses carrying randomly mutated naïve proteases from early or recent sample isolates (P = 0.8035). Interestingly, a significantly greater loss of RC was observed in the PI-resistant protease group (P = 0.0400). These results demonstrate that protease sequence diversification has not affected HIV-1 RC or protease robustness and indicate that proteases carrying PI resistance substitutions are less robust than naïve proteases.
Women's work interruptions and career prospects in Germany and Sweden
Authors: Evertsson Marie , Grunow Daniela
Published: August 2012

Purpose

The purpose of this paper is to focus on two welfare state regimes with differing degrees of de‐familialisation strategies, Germany and Sweden, to study whether and how women's career interruptions influence their labour market prospects. By comparing women with continuous careers to those with discontinuous careers due to: parental leave or homemaking; unemployment; or other reasons, the authors explore the support for the skill depreciation hypothesis and signalling theory. Depending on the type of welfare state regime, the authors expect women to be subject to varying degrees of career punishment for time spent out of the labour market.

Design/methodology/approach

Cox proportional hazard regression models of the transition rate of an upward or downward occupational move among women in the labour market were estimated.

Findings

Focusing on upward career moves, the results show no significant relationship between a career interruption and upward occupational moves in Germany. In Sweden, the longer the accumulated duration of family leave, the lower the transition rate to an upward move. Overall occupational mobility is higher in Sweden, and in a policy regime where almost all women work, extended leaves may have a more negative effect on career prospects than in Germany, where many mothers drop out of the labour force altogether. In Germany, on the other hand, the authors find traces of unemployment to be scarring, as the risk of downward moves increases with increased unemployment experience.

Originality/value

The paper explores the impact of policies in shaping women's career trajectories and critically examines the often‐cited skill depreciation hypothesis.
Internationalization pathways among family‐owned SMEs
Authors: Kontinen Tanja , Ojala Arto
Published: August 2012

Purpose

The purpose of this paper is to increase understanding of the internationalization of family firms; to investigate how the framework by Bell et al. on the internationalization patterns of firms could explain the internationalization pathways taken by family‐owned small to medium‐sized enterprises (SMEs); and to identify typical patterns and features in the various pathways taken by family‐owned SMEs.

Design/methodology/approach

This paper reports findings from an in‐depth multiple case study with eight Finnish family‐owned SMEs.

Findings

The ownership structure had the most important role in defining the internationalization pathways followed by the family‐owned SMEs: a fragmented ownership structure led to traditional internationalization pathway whereas a concentrated ownership base led to born global or born‐again global pathways.

Practical implications

Family entrepreneurs should carefully consider the division of ownership and seek to build new relationships in foreign markets, in addition to their primary co‐operators.

Originality/value

The authors extend the integrative model of small firm internationalization by Bell et al. toward family‐owned SMEs and highlight the most important dimensions in the different internationalization pathways of family SMEs. The ownership dimension is integrated within discussion on differing internationalization pathways. The authors utilize a family business specific perspective (the stewardship perspective), in order to understand the specific features of internationalization among family SMEs, and also how these features differ between family SMEs and other firms.
Early internationalization and performance of small high‐tech “born‐globals”
Authors: Li Lee , Qian Gongming , Qian Zhengming
Published: August 2012

Purpose

The purpose of this paper is to investigate the early internationalization and the performance of small firms in technology‐intensive industries.

Design/methodology/approach

Using a sample of 278 small US firms in technology‐intensive industries, this paper employs quantitative methodologies to test hypotheses.

Findings

The findings indicate that such organizational variables as firm size and international experience have a non‐linear, inverted U‐shaped relationship with these firms’ early internationalization. Some strategic variables, such as R&D intensity, have significant impacts, whereas others, such as advertising intensity and strategic alliances, have none. However, the interactions between these strategic variables have a more significant influence upon these firms’ early internationalization than do the individual strategic variables in isolation. Moreover, early internationalization has significant and positive impacts on the performance of these firms.

Practical implications

The paper’s findings have important managerial implications. The paper identifies the driving forces for the early globalization of small firms and provides useful guidelines for managers to manage these factors in their efforts to maximize firm performance.

Originality/value

The paper differentiates organizational factors from strategic factors against the background of small “born globals” in technology industries and investigates the interactions among these internal factors and external factors, i.e. the environments of technology industries. Findings of non‐linear relationships among these factors shed light on the strategy determinants of a unique group of small to medium‐sized enterprises and their performance.
How leadership for an ICT reform is distributed within a school
Authors: Ng Foo Seong David , Ho Jeanne Marie
Published: August 2012

Purpose

The purpose of this paper is to examine the process of information communication technology (ICT) reform in a government school in Singapore. The focus is on the distributed leadership actions performed by various individuals, and how the multiple leaders and their leadership practices interacted with one another.

Design/methodology/approach

A naturalistic inquiry approach was adopted, involving the case study of a school in the process of implementing an instructional reform involving the use of ICT.

Findings

It was found that distributed leadership for ICT implementation requires a combination of transformational leadership and instructional leadership to develop teachers’ capacity to enhance their instruction with ICT, emotional leadership to support teachers’ effort to change, and strategic management of resources to sustain teachers’ change efforts. Transformational leadership is performed mainly by senior management (SM). Instructional leadership is performed mainly by middle management (MM). Both senior and middle management provided emotional leadership and strategic resource management. In addition, SM provided second‐order changes leadership, while MM provided first‐order changes leadership.

Originality/value

The paper rectifies the current disproportionate focus on the role of the Principal by uncovering the leadership actions performed by other school members, and how these leadership actions are interrelated. In particular, the paper provides insight into how leadership was distributed in a school reform involving the use of ICT for instruction.
Do the managerial characteristics of schools influence their performance?
Authors: Agasisti Tommaso , Bonomi Francesca , Sibiano Piergiacomo
Published: August 2012

Purpose

The purpose of this paper is to investigate the role of governance and managerial characteristics of schools. More specifically, the aim is to individuate the factors that are associated to higher schools’ performances, as measured through student achievement.

Design/methodology/approach

The research is conducted by means of a survey in the private junior‐secondary schools in one Italian region (Lombardy).

Findings

The results show that some features characterize the group of “high‐performing” schools: the presence of structured tests to measure student’ achievement; specific services for disabled and foreign students; a high level of principal's autonomy in strategic decision making; the use of assessment for defining strategies; and a high collaborative attitude among teachers.

Research limitations/implications

The present paper focused only on the private sector, because non‐public schools benefit from a substantial autonomy in their organizational and managerial profile. Some of the indicators collected in this study could be included in the Italian standardized tests’ protocol, by creating an ad hoc school's questionnaire.

Originality/value

This paper answers to the call by educational research, applied economic research and present institutional assessment activities for a renewed desire to build reliable indicators about schools’ performance in Italy. In this paper an analytical framework is developed to collect relevant information about schools’ characteristics.