bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic structure and bulk properties of MB6 and MB12 borides
Authors: Grechnev G. E. , Baranovskiy A. E. , Fil V. D. , Ignatova T. V. , Kolobov I. G. , Logosha A. V. , Shitsevalova N. Yu. , Filippov V. B. , Eriksson Olle
Published: November 2008

Ab initio band structure calculations are carried out for the higher borides MB6 and MB12. High-precision measurements of the elastic constants are performed for the compounds ZrB12, HoB12, ErB12, TmB12, LuB12, YB6 and LaB6 at low temperatures. The bulk properties of the borides are analyzed on the basis of the calculated equations of states and balanced crystal orbital overlap populations. Our calculations indicate that hexaborides with divalent metals, CaB6, SrB6, BaB6, and YbB6, are semiconductors with small energy gaps. The metallic MB6 hexaborides with trivalent M atoms are found to possess larger bulk moduli values. For dodecaborides the bulk moduli are found to be higher for MB12 with increased filling of the conduction band (ZrB12, HfB12, UB12) in comparison with M3+B12 compounds. The total energy calculations for different magnetic configurations in YbB12 point to the possibility of antiferromagnetic coupling between Yb3+ ions.
Overheating effect and hole-phonon interaction in SiGe heterostructures
Authors: Berkutov I. B. , Andrievskii V. V. , Komnik Yu. F. , Myronov M. , Mironov O. A.
Published: November 2008

The effect of charge-carrier overheating in a two-dimensional (2D) hole gas is realized in a Si1−xGex quantum well, where x=0.13, 0.36, 0.8, or 0.95. The Shubnikov–de Haas (SdH) oscillation amplitude is used as a “thermometer” to measure the temperature of overheated holes. The temperature dependence of the hole-phonon relaxation time is found from an analysis of the change of the dependence of the amplitude of the SdH oscillations on temperature and applied electrical field. Analysis of the temperature dependence of the hole-phonon relaxation time reveals a transition of the 2D system from the regime of “partial inelasticity” to conditions of small-angle scattering.
Sub-9 Å equivalent oxide thickness scaling using hafnium zirconate dielectric with tantalum carbide gate
Authors: Hegde R. I. , Triyoso D. H.
Published: November 2008

This paper reports on hafnium zirconate (HfxZr1−xO2) gate dielectric capacitance equivalent thickness scaling below 14 Å and equivalent oxide thickness scaling below 9 Å. This is accomplished by careful optimization of the HfxZr1−xO2 thickness and ammonia (NH3) postdeposition anneal (PDA) conditions with tantalum carbide (TaxCy) metal gate. Further, the various process schemes employed for the thickness scaling such as pretreatment, PDA, metal capping, and metal-oxide doping of HfxZr1−xO2 will be described. Finally, the attributes and possible mechanisms of NH3 PDA to reduce the thickness of interfacial layer and the thickness of the HfxZr1−xO2 layer for the oxide thickness scaling will be discussed.
Modifications of yttria fully stabilized zirconia thin films by ion irradiation in the inelastic collision regime
Authors: Caricato A. P. , Lamperti A. , Ossi P. M. , Trautmann C. , Vanzetti L.
Published: November 2008

Yttria fully stabilized zirconia (FSZ) is a candidate material for nuclear inert matrix fuel cell and nuclear waste containment due to its isostructure with UO2 and PuO2 and its outstanding radiation resistance. Amorphous and polycrystalline cubic FSZ thin films of thickness around 400 nm were deposited on (100) Si by ultraviolet pulsed laser ablation and irradiated with 2.6 GeV uranium ions at fluences between 2×1011 and 1.2×1012 ions cm−2. The films were characterized before and after irradiation using scanning electron microscopy, atomic force microscopy, grazing incidence x-ray diffraction, and x-ray photoelectron spectroscopy (XPS). Amorphization, followed by partial recrystallization, is observed for irradiated crystalline films, whereas the amorphous films remain unaltered. A shift in the relative position of the XPS Zr 3d, Y 3d, and O 1s core lines is observed upon irradiation both in the crystalline and amorphous films, indicating differences in the local chemical environment at the surface as well as in near-surface layers. Such changes are ascribed to oxygen migration at the film surface, which may promote the recrystallization of as-deposited crystalline films but does not affect amorphous films.
Role of secondary long wavelength structures in the saturation of electron temperature gradient driven turbulence
Authors: Li Jiquan , Kishimoto Y.
Published: November 2008

The dynamics of secondary long wavelength structures (LWSs) in electron temperature gradient (ETG) driven turbulence are investigated by performing gyrofluid simulations and modeling analyses in a slab geometry with an emphasis of the underlying nonlinear interaction processes. It is shown that the back-reaction of the secondary LWS on the ambient fluctuations essentially contributes to saturating ETG instability and limiting the electron transport. The LWS is nonlinearly generated mainly through the beating of the most unstable ETG modes, even a weak modulation instability. The back-reaction is identified as the enhanced stabilization of the ETG modes due to the streamer-type feature of the LWS, which dominantly produces a local poloidal mode coupling among unstable and highly damped spectral components to form a global mode, besides the suppression effect of the LWS due to the radial shearing decorrelation and/or the radial mode coupling. Finally, the correspondence between the LWS in the slab model and the quasimode observed in toroidal ETG simulation [Z. Lin et al., Phys. Plasmas 12, 056125 (2005)] and the importance of the nonlinear mode coupling in the multiscale turbulence interaction are discussed.
Monogamy equality in 2⊗2⊗d quantum systems
Authors: Chi Dong Pyo , Choi Jeong Woon , Jeong Kabgyun , San Kim Jeong , Kim Taewan , Lee Soojoon
Published: November 2008

There is an interesting property about multipartite entanglement, called the monogamy of entanglement. The property can be shown by the monogamy inequality, called the Coffman–Kundu–Wootters inequality [Phys. Rev. A 61, 052306 (2000); Coffman–Kundu–WoottersPhys. Rev. Lett. 96, 220503 (2006)], and more explicitly by the monogamy equality in terms of the concurrence and the concurrence of assistance, CA(BC)2=CAB2+(CACa)2, in the three-qubit system. In this paper, we consider the monogamy equality in 2⊗2⊗d quantum systems. We show that CA(BC)=CAB if and only if CACa=0 and also show that if CA(BC)=CACa, then CAB=0, while there exists a state in a 2⊗2⊗d system such that CAB=0 but CA(BC)>CACa.
Optical activity in extrinsically chiral metamaterial
Authors: Plum E. , Fedotov V. A. , Zheludev N. I.
Published: November 2008

We demonstrate optical activity in an intrinsically non-chiral anisotropic planar metamaterial. The phenomenon is due to extrinsic chirality resulting from the mutual orientation of the metamaterial structure and the incident electromagnetic wave. The polarization effect, which has a resonant nature, features a spectral band where linear birefringence is practically absent and can be easily tuned by tilting the plane of the metamaterial relative to the incident beam.
Liquid phase direct laser printing of polymers for chemical sensing applications
Authors: Boutopoulos Christos , Tsouti Vasiliki , Goustouridis Dimitrios , Chatzandroulis Stavros , Zergioti Ioanna
Published: November 2008

This letter demonstrates the direct laser printing of polymers on capacitive micromechanical arrays for the realization of a chemical sensor. Each sensor of a single chip array is composed of a thin Si membrane covered by a chemically sensitive polymer layer by means of a direct laser printing technique. We present the high spatial resolution deposition of three different sensitive polymer materials by the liquid phase laser induced forward transfer process. We also show that the optimum sensitivity of the sensors can be achieved by varying the percentage of the coverage of the sensors’ membranes with the polymer.
A mean field approach to many-particles effects in dielectrophoresis
Authors: Nicotra O. E. , La Magna A. , Coffa S.
Published: November 2008

One of the major applications of the dielectrophoresis is selective trapping and fractionation in lab-on-a-chip devices. Nevertheless, many-particles effects due to high concentration of biological material around electrodes can cause a rapid decrease in trapping efficiency in dielectrophoretic devices. In this paper we present an approach based on a drift-diffusion dynamics to study the particles behavior near electrodes surroundings. Within this approach, we introduce many-particles effects by invoking the effective medium approximation, electrodes can saturate losing their capability to attract further particles and thus leading to a more realistic scenario never shown in past literature.
A dual-resonant terahertz metamaterial based on single-particle electric-field-coupled resonators
Authors: Yuan Yu , Bingham Christopher , Tyler Talmage , Palit Sabarni , Hand Thomas H. , Padilla Willie J. , Jokerst Nan Marie , Cummer Steven A.
Published: November 2008

We report the design, fabrication, and measurement of a terahertz metamaterial composed of single geometry electric field coupled resonators that has two closely spaced electric resonances near 1.0 and 1.5THz. Due to the mutual coupling between the different resonances in the particle, the lower frequency resonance of this metamaterial is stronger than that in a metamaterial composed of identically sized single-resonant particles, leading to a larger insertion loss and broader bandwidth. This feature provides more flexibility in metamaterial design and application in the terahertz regime.
Structure map for embedded binary alloy nanocrystals
Authors: Yuan C. W. , Shin S. J. , Liao C. Y. , Guzman J. , Stone P. R. , Watanabe M. , Ager J. W. , Haller E. E. , Chrzan D. C.
Published: November 2008

The equilibrium structure of embedded nanocrystals formed from strongly segregating binary alloys is considered within a simple thermodynamic model. The model identifies two dimensionless interface energies that dictate the structure and allows prediction of the stable structure for any choice of these parameters. The resulting structure map includes three distinct nanocrystal morphologies: core/shell, lobe/lobe, and completely separated spheres.
Chirality of sulforhodamine dye molecules incorporated in DNA thin films
Authors: Steckl A. J. , Spaeth H. , Singh K. , Grote J. , Naik R.
Published: November 2008

Thin films formed from salmon sperm DNA reacted with a cationic surfactant (CTMA-Cl) included up to 25 wt % fluorescent molecule sulforhodamine (SRh). SRh effect on DNA chirality and vice versa was investigated by circular dichroism (CD) spectroscopy. The CD signals at 250–265 nm indicate that DNA chirality was maintained or enhanced. Induced CD (iCD) signal at 580–610 nm indicates that SRh is chiral in DNA/CTMA. iCD signal from both solutions and thin films generally increases with SRh concentration. The chirality induced in SRh molecules and the absence of significant DNA reduction in chirality are clear indicators of strong binding to DNA/CTMA.
A monolithically integrated magneto-optoelectronic circuit
Authors: Saha D. , Basu D. , Bhattacharya P.
Published: November 2008

The monolithic integration of a spin valve, an amplifier, and a light emitting diode to form a magneto-optoelectronic integrated circuit on GaAs is demonstrated. The circuit converts the spin polarization information in the channel of the spin valve to an amplified change in light intensity with a gain of 20. The monolithic circuit therefore operates as a magnetoelectronic switch which modulates the light intensity of the light emitting diode.
Serum response factor orchestrates nascent sarcomerogenesis and silences the biomineralization gene program in the heart
Authors: Niu Zhiyv , Iyer Dinakar , Conway Simon J. , Martin James F. , Ivey Kathryn , Srivastava Deepak , Nordheim Alfred , Schwartz Robert J.
Published: November 2008

Our conditional serum response factor (SRF) knockout,

Srf
Cko

, in the heart-forming region blocked the appearance of rhythmic beating myocytes, one of the earliest cardiac defects caused by the ablation of a cardiac-enriched transcription factor. The appearance of Hand1 and Smyd1, transcription and chromatin remodeling factors; Acta1, Acta2, Myl3, and Myom1, myofibril proteins; and calcium-activated potassium-channel gene activity (KCNMB1), the channel protein, were powerfully attenuated in the

Srf
CKO

mutant hearts. A requisite role for combinatorial cofactor interactions with SRF, as a major determinant for regulating the appearance of organized sarcomeres, was shown by viral rescue of SRF-null ES cells with SRF point mutants that block cofactor interactions. In the absence of SRF genes associated with biomineralization, GATA-6, bone morphogenetic protein 4 (BMP4), and periostin were strongly up-regulated, coinciding with the down regulation of many SRF dependent microRNA, including miR1, which exerted robust silencer activity over the induction of GATA-6 leading to the down regulation of BMP4 and periostin.
The transcriptional regulator PLZF induces the development of CD44 high memory phenotype T cells
Authors: Raberger Julia , Schebesta Alexandra , Sakaguchi Shinya , Boucheron Nicole , Blomberg K. Emelie M. , Berglöf Anna , Kolbe Thomas , Smith C. I. Edvard , Rülicke Thomas , Ellmeier Wilfried
Published: November 2008

Transcriptional pathways controlling the development of CD44
hi
memory phenotype (MP) T cells with “innate-like” functions are not well understood. Here we show that the BTB (bric-a-brac, tramtrack, broad complex) domain-containing protein promyelocytic leukemia zinc finger (PLZF) is expressed in CD44
hi
, but not in CD44
lo
, CD4
+
T cells. Transgenic expression of PLZF during T cell development and in CD4
+
and CD8
+
T cells induced a T cell intrinsic program leading to an increase in peripheral CD44
hi
MP CD4
+
and CD8
+
T cells and a corresponding decrease of naïve CD44
lo
T cells. The MP CD4
+
and CD8
+
T cells produced IFNγ upon PMA/ionomycin stimulation, thus showing innate-like function. Changes in the naïve versus memory-like subset distribution were already evident in single-positive thymocytes, indicating PLZF-induced T cell developmental alterations. In addition, CD1d-restricted natural killer T cells in PLZF transgenic mice showed impaired development and were severely reduced in the periphery. Finally, after anti-CD3/CD28 stimulation, CD4
+
transgenic T cells showed reduced IL-2 and IFNγ production but increased IL-4 secretion as a result of enhanced IL-4 production of the CD44
hi
CD62L
+
subset. Our data indicate that PLZF is a novel regulator of the development of CD44
hi
MP T cells with a characteristic partial innate-like phenotype.
Thymus leukemia antigen controls intraepithelial lymphocyte function and inflammatory bowel disease
Authors: Olivares-Villagómez Danyvid , Mendez-Fernandez Yanice V. , Parekh Vrajesh V. , Lalani Saif , Vincent Tiffaney L. , Cheroutre Hilde , Van Kaer Luc
Published: November 2008

Intestinal intraepithelial lymphocytes (IEL) bear a partially activated phenotype that permits them to rapidly respond to antigenic insults. However, this phenotype also implies that IEL must be highly controlled to prevent misdirected immune reactions. It has been suggested that IEL are regulated through the interaction of the CD8αα homodimer with the thymus leukemia (TL) antigen expressed by intestinal epithelial cells. We have generated and characterized mice genetically-deficient in TL expression. Our findings show that TL expression has a critical role in maintaining IEL effector functions. Also, TL deficiency accelerated colitis in a genetic model of inflammatory bowel disease. These findings reveal an important regulatory role of TL in controlling IEL function and intestinal inflammation.
Optical lock-in detection imaging microscopy for contrast-enhanced imaging in living cells
Authors: Marriott Gerard , Mao Shu , Sakata Tomoyo , Ran Jing , Jackson David K. , Petchprayoon Chutima , Gomez Timothy J. , Warp Erica , Tulyathan Orapim , Aaron Holly L. , Isacoff Ehud Y. , Yan Yuling
Published: November 2008

One of the limitations on imaging fluorescent proteins within living cells is that they are usually present in small numbers and need to be detected over a large background. We have developed the means to isolate specific fluorescence signals from background by using lock-in detection of the modulated fluorescence of a class of optical probe termed “optical switches.” This optical lock-in detection (OLID) approach involves modulating the fluorescence emission of the probe through deterministic, optical control of its fluorescent and nonfluorescent states, and subsequently applying a lock-in detection method to isolate the modulated signal of interest from nonmodulated background signals. Cross-correlation analysis provides a measure of correlation between the total fluorescence emission within single pixels of an image detected over several cycles of optical switching and a reference waveform detected within the same image over the same switching cycles. This approach to imaging provides a means to selectively detect the emission from optical switch probes among a larger population of conventional fluorescent probes and is compatible with conventional microscopes. OLID using nitrospirobenzopyran-based probes and the genetically encoded Dronpa fluorescent protein are shown to generate high-contrast images of specific structures and proteins in labeled cells in cultured and explanted neurons and in live
Xenopus
embryos and zebrafish larvae.
Cytoskeletal Tropomyosin Tm5NM1 Is Required for Normal Excitation–Contraction Coupling in Skeletal Muscle
Authors: Vlahovich Nicole , Kee Anthony J. , Van der Poel Chris , Kettle Emma , Hernandez-Deviez Delia , Lucas Christine , Lynch Gordon S. , Parton Robert G. , Gunning Peter W. , Hardeman Edna C.
Published: November 2008

The functional diversity of the actin microfilaments relies in part on the actin binding protein tropomyosin (Tm). The muscle-specific Tms regulate actin-myosin interactions and hence contraction. However, there is less known about the roles of the numerous cytoskeletal isoforms. We have shown previously that a cytoskeletal Tm, Tm5NM1, defines a Z-line adjacent cytoskeleton in skeletal muscle. Recently, we identified a second cytoskeletal Tm in this region, Tm4. Here we show that Tm4 and Tm5NM1 define separate actin filaments; the former associated with the terminal sarcoplasmic reticulum (SR) and other tubulovesicular structures. In skeletal muscles of Tm5NM1 knockout (KO) mice, Tm4 localization was unchanged, demonstrating the specificity of the membrane association. Tm5NM1 KO muscles exhibit potentiation of T-system depolarization and decreased force rundown with repeated T-tubule depolarizations consistent with altered T-tubule function. These results indicate that a Tm5NM1-defined actin cytoskeleton is required for the normal excitation–contraction coupling in skeletal muscle.
Fibroblast Growth Factor Receptor-induced Phosphorylation of EphrinB1 Modulates Its Interaction with Dishevelled
Authors: Lee Hyun-Shik , Mood Kathleen , Battu Gopala , Ji Yon Ju , Singh Arvinder , Daar Ira O.
Published: November 2008

The Eph family of receptor tyrosine kinases and their membrane-bound ligands, the ephrins, have been implicated in regulating cell adhesion and migration during development by mediating cell-to-cell signaling events. The transmembrane ephrinB1 protein is a bidirectional signaling molecule that signals through its cytoplasmic domain to promote cellular movements into the eye field, whereas activation of the fibroblast growth factor receptor (FGFR) represses these movements and retinal fate. In Xenopus embryos, ephrinB1 plays a role in retinal progenitor cell movement into the eye field through an interaction with the scaffold protein Dishevelled (Dsh). However, the mechanism by which the FGFR may regulate this cell movement is unknown. Here, we present evidence that FGFR-induced repression of retinal fate is dependent upon phosphorylation within the intracellular domain of ephrinB1. We demonstrate that phosphorylation of tyrosines 324 and 325 disrupts the ephrinB1/Dsh interaction, thus modulating retinal progenitor movement that is dependent on the planar cell polarity pathway. These results provide mechanistic insight into how fibroblast growth factor signaling modulates ephrinB1 control of retinal progenitor movement within the eye field.
Deciliation Is Associated with Dramatic Remodeling of Epithelial Cell Junctions and Surface Domains
Authors: Overgaard Christian E. , Sanzone Kaitlin M. , Spiczka Krystle S. , Sheff David R. , Sandra Alexander , Yeaman Charles
Published: November 2008

Stress-induced shedding of motile cilia (autotomy) has been documented in diverse organisms and likely represents a conserved cellular reaction. However, little is known about whether primary cilia are shed from mammalian epithelial cells and what impact deciliation has on polarized cellular organization. We show that several chemically distinct agents trigger autotomy in epithelial cells. Surprisingly, deciliation is associated with a significant, but reversible increase in transepithelial resistance. This reflects substantial reductions in tight junction proteins associated with “leaky” nephron segments (e.g., claudin-2). At the same time, apical trafficking of gp80/clusterin and gp114/CEACAM becomes randomized, basal-lateral delivery of Na,K-ATPase is reduced, and expression of the nonciliary apical protein gp135/podocalyxin is greatly decreased. However, ciliogenesis-impaired MDCK cells do not undergo continual junction remodeling, and mature cilia are not required for autotomy-associated remodeling events. Deciliation and epithelial remodeling may be mechanistically linked processes, because RNAi-mediated reduction of Exocyst subunit Sec6 inhibits ciliary shedding and specifically blocks deciliation-associated down-regulation of claudin-2 and gp135. We propose that ciliary autotomy represents a signaling pathway that impacts the organization and function of polarized epithelial cells.
Analysis of Uromodulin Polymerization Provides New Insights into the Mechanisms Regulating ZP Domain-mediated Protein Assembly
Authors: Schaeffer Céline , Santambrogio Sara , Perucca Simone , Casari Giorgio , Rampoldi Luca
Published: November 2008

Uromodulin is the most abundant protein secreted in urine, in which it is found as a high-molecular-weight polymer. Polymerization occurs via its zona pellucida (ZP) domain, a conserved module shared by many extracellular eukaryotic proteins that are able to assemble into matrices. In this work, we identified two motifs in uromodulin, mapping in the linker region of the ZP domain and in between protein cleavage and glycosylphosphatidylinositol (GPI)-anchoring sites, which regulate its polymerization. Indeed, mutations in either module led to premature intracellular polymerization of a soluble uromodulin isoform, demonstrating the inhibitory role of these motifs for ZP domain-mediated protein assembly. Proteolytic cleavage separating the external motif from the mature monomer is necessary to release the inhibitory function and allow protein polymerization. Moreover, we report absent or abnormal assembly into filaments of GPI-anchored uromodulin mutated in either the internal or the external motif. This effect is due to altered processing on the plasma membrane, demonstrating that the presence of the two modules has not only an inhibitory function but also can positively regulate protein polymerization. Our data expand previous knowledge on the control of ZP domain function and suggest a common mechanism regulating polymerization of ZP domain proteins.
Biocontrol of Lettuce Drop Caused by Sclerotinia sclerotiorum and S. minor in Desert Agroecosystems
Authors: Chitrampalam P. , Figuli P. J. , Matheron M. E. , Subbarao K. V. , Pryor B. M.
Published: November 2008

Field experiments were conducted over 2 years in Yuma County, AZ, and Imperial County, CA, to determine the efficacy of several biocontrol agents for the management of lettuce drop caused by Sclerotinia spp. Commercial formulations of Trichoderma harzianum (Plantshield, Supersivit), Gliocladium virens (Soilgard), Coniothyrium minitans (Contans), and Bacillus subtilis (Companion) were evaluated and compared with the chemical fungicide iprodione (Rovral) against Sclerotinia sclerotiorum and S. minor. A single application of biocontrol products or of Rovral did not reduce lettuce drop caused by either Sclerotinia species. However, two applications of Contans, one at planting and one at post-thinning, significantly reduced the incidence of lettuce drop caused by S. sclerotiorum and increased yield but had no effect on S. minor at both locations in both years. Two applications of other biocontrol products did not significantly reduce disease incidence despite medium to high recovery following application. In contrast, Contans was only sporadically recovered following application. In vitro fungicide sensitivity evaluation revealed that both Trichoderma and Gliocladium species were tolerant to iprodione, dicloran (Botran), and vinclozolin (Ronilan) up to 1,000 ppm a.i., whereas both Sclerotinia spp. and C. minitans were sensitive to all three fungicides above 1 ppm. In summary, Contans was the most effective treatment for the control of lettuce drop caused by S. sclerotiorum, but no treatment was effective against S. minor in the desert lettuce production systems.
Molecular Mapping of a Leaf Rust Resistance Gene on the Short Arm of Chromosome 6B of Durum Wheat
Authors: Herrera-Foessel S. A. , Singh R. P. , Huerta-Espino J. , William H. M. , Djurle A. , Yuen J.
Published: November 2008

Leaf rust, caused by Puccinia triticina, is an important disease of durum wheat (Triticum turgidum subsp. durum) worldwide, and the most effective way to control it is through the use of resistant cultivars. A partially dominant leaf rust resistance gene present in the International Maize and Wheat Improvement Center-derived Chilean cv. Guayacan INIA and its sister line Guayacan 2 was mapped to chromosome arm 6BS by identifying linked amplified fragment length polymorphisms (AFLPs) and mapping two of the molecular markers in common wheat (T. aestivum) linkage maps of the International Triticeae Mapping Initiative and Oligoculm × Fukuho-komugi populations. Comparison of infection type responses of the two resistant durums with common wheat testers carrying the previously mapped resistance genes Lr36 and Lr53 on 6BS, and their chromosomal positions, indicated that the resistance gene in durum wheat Guayacan INIA is a new leaf rust resistance gene, which was designated as Lr61. Gene Lr61 is effective against the P. triticina race BBG/BN predominant in northwestern Mexico and other races infecting durum wheat in various countries.
Influence of Temperature on Pathogenicity of Pythium volutum Toward Creeping Bentgrass
Authors: Kerns J. P. , Tredway L. P.
Published: November 2008

Symptoms of Pythium root dysfunction (PRD) in creeping bentgrass (Agrostis stolonifera) are most common in the summer during periods of heat and drought stress. However, recent observations in North Carolina indicate that Pythium volutum, a causal agent of PRD, is most active during the fall and spring. Soil temperature thresholds for this pathogen are needed so that preventive fungicide applications can be timed accurately. A mycelial growth assay was performed by incubating 11 P. volutum isolates at 10 temperatures ranging from 10 to 31°C. To determine the optimal temperature range for infection by P. volutum, five isolates of P. volutum were used to inoculate 5-week-old ‘Penn A-1’ creeping bentgrass plants. Inoculated plants were transferred to growth chambers at constant 12, 16, 20, 24, 28, or 32°C (12-h day/night cycles) for 4 weeks to permit root infection, then the temperature in all chambers was increased to 32/26°C day/night to induce foliar symptoms. P. volutum grew most rapidly in vitro when temperatures were between 18 and 26°C. Typical PRD foliar symptoms developed in the 12, 16, 20, and 24°C treatments 2 weeks after the temperature was elevated to 32/26°C day/night. Disease severity was greatest when plants were incubated at 16°C after inoculation. Reductions in root depth and/or root mass were observed prior to raising the temperature to 32/26°C in the 12, 16, and 20°C temperature treatments. Once exposed to 4 weeks of heat treatment, extensive root dieback occurred in the 12, 16, 20, and 24°C treatments. These results demonstrate that P. volutum is most active at temperatures prevalent during the fall and spring in North Carolina, supporting the hypothesis that the majority of root infection occurs during this time and that fungicides should be applied when soil temperatures are between 12 and 24°C to achieve preventative control of PRD symptoms in the summer.
Systemic Infection by Fusarium verticillioides in Maize Plants Grown Under Three Temperature Regimes
Authors: Murillo-Williams A. , Munkvold G. P.
Published: November 2008

Fusarium verticillioides causes seedling decay, stalk rot, ear rot, and mycotoxin contamination (primarily fumonisins) in maize. Systemic infection of maize plants by F. verticillioides can lead to kernel infection, but the frequency of this phenomenon has varied widely among experiments. Variation in the incidence of systemic infection has been attributed to environmental factors. In order to better understand the influence of environment, we investigated the effect of temperature on systemic development of F. verticillioides during vegetative and reproductive stages of plant development. Maize seeds were inoculated with a green fluorescent protein-expressing strain of F. verticillioides, and grown in growth chambers under three different temperature regimes. In the vegetative-stage and reproductive-stage experiments, plants were evaluated at tasseling (VT stage), and at physiological maturity (R6 stage), respectively. Independently of the temperature treatment, F. verticillioides was reisolated from nearly 100% of belowground plant tissues. Frequency of reisolation of the inoculated strain declined acropetally in aboveground internodes at all temperature regimes. At VT, the high-temperature treatment had the highest systemic development of F. verticillioides in aboveground tissues. At R6, incidence of systemic infection was greater at both the high- and low-temperature regimes than at the average-temperature regime. F. verticillioides was isolated from higher internodes in plants at R6, compared to stage VT. The seed-inoculated strain was recovered from kernels of mature plants, although incidence of kernel infection did not differ significantly among treatments. During the vegetative growth stages, temperature had a significant effect on systemic development of F. verticillioides in stalks. At R6, the fungus reached higher internodes in the high-temperature treatment, but temperature did not have an effect on the incidence of kernels (either symptomatic or asymptomatic) or ear peduncles infected with the inoculated strain. These results support the role of high temperatures in promoting systemic infection of maize by F. verticillioides, but plant-to-seed transmission may be limited by other environmental factors that interact with temperature during the reproductive stages.
First Report of Tilletia pulcherrima Bunt on Switchgrass (Panicum virgatum) in Texas
Authors: Carris L. M. , Castlebury L. A. , Zale J.
Published: November 2008

Switchgrass seed samples of ‘Blackwell’ and ‘Alamo’ from Bailey County, TX were examined for bunt fungi. Fourteen completely bunted seeds of ‘Blackwell’ and four of ‘Alamo’ were found. No partially bunted seeds were found. Bunted seeds were darker and occasionally slightly swollen relative to noninfected seeds. Teliospores were globose to subglobose, 21 to 28 × 20 to 27 μm in diameter, dark reddish brown to nearly black, with blunt warts 1 to 1.8 μm long, enveloped in a hyaline sheath, and often with a short apiculus. Sterile cells were globose to subglobose, 17.5 to 22 μm, with smooth, laminated walls as much as 2.6 μm thick, and often with a short apiculus. This bunt was identified as Tilletia pulcherrima Ellis & Galloway on the basis of host and spore morphology (2). The internal transcribed spacer regions 1 and 2, including the 5.8S rDNA, were sequenced from bunted ‘Blackwell’ seeds (GenBank Accession No. EU915293, WSP 71501). The sequence was distinct from all Tilletia sequences in GenBank, including Tilletia barclayana (Bref.) Sacc. & Syd. on Panicum obtusum Kunth (GenBank Accession No. AF 310169) (1). To our knowledge, this is the first report of T. pulcherrima from switchgrass in Texas. Plant pathologists and regulatory officials should be aware of the potential for misidentification of T. pulcherrima as T. indica Mitra, the Karnal bunt pathogen of wheat that has similar spores, occurs in Texas, and has quarantine status.

References: (1) R. Durán and G. W. Fischer. The Genus Tilletia, Washington State University, Pullman, WA, 1961. (2) K. Vánky, Mycotaxon 91:217, 2005.
First Report of Orobanche crenata on Sulla (Hedysarum coronarium) in Andalusia, Southern Spain
Authors: Córdoba E. , González-Verdejo C. I. , Die J. , Román B. , Nadal S.
Published: November 2008

Crenata broomrape (Orobanche crenata Forsk.), an obligate chlorophyll-lacking root parasite, is the major constraint for growing legume crops in infested soils in southern Spain. Peas (Pisum sativum L), faba beans (Vicia faba L.), and narbon bean (Vicia narbonensis L.) are seriously affected (1,2,4). However, no information is available regarding its ability to attack sulla (Hedysarum coronarium L.), which is an important fodder legume grown in rain-fed conditions, yielding as much as 10,000 kg/ha of dry matter. In 2008, we found broomrape shoots infecting 4 to 5% of sulla plants in a trial field (two land races, P-26 and P-3, in a 500-m2 area) in Cordoba (Andalusia, southern Spain). The shoots developed numerous fertile flowering stalks throughout the field. The previous crop, narbon bean, was heavily infected during 2007 by O. crenata. Infection of sulla plants was confirmed by digging up the plant to verify the attachment of the broomrape plant to the sulla roots. The level of infection was low with only one to two emerged broomrape shoots per sulla plant infested. Morphology was typical of O. crenata. The calyx of the flowers was 13 to 18 mm long with free, bidentate segments. The white corolla of the flowers was 18 to 28 mm long and glandular pubescent. The lips were divergent, large, not ciliate, and filaments inserted 2 to 3 mm above the base of the corolla are hairy at base with glandular hair at the apex. The anthers were brown (3). Specimens were deposited in the Herbarium of the University of Córdoba (identification number COA 45358). To our knowledge, this first report of O. crenata parasitizing sulla shows that control methods for O. crenata will be needed if sulla is to be used as an alternative legume fodder in the infested soils of southern Spain.

References: (1) J. I. Cubero and M. T. Moreno. Page 41 in: Some Current Research on Vicia faba in Western Europe. D. A. Bond et al., eds. Luxembourg, 1979. (2) S. Nadal et al. Plant Breed. 126:110, 2007. (3) A. J. Pujadas-Salvá. Page 187 in: Resistance to Orobanche: The State of the Art. Junta de Andalucía, Sevilla, Spain, 1999. (4) D. Rubiales et al. Crop Prot. 22:865, 2003.
First Report of White Mold Caused by Sclerotinia sclerotiorum on Borago officinalis in Italy
Authors: Garibaldi A. , Pensa P. , Bertetti D. , Gullino M. L.
Published: November 2008

Borago officinalis L. (common borage) is a flowering plant belonging to the Boraginaceae with several culinary and medicinal uses and grown in soil or as potted plants in Liguria (northern Italy). At the end of winter in 2008, extensive chlorosis was observed on potted plants of B. officinalis grown in containers on a farm near Albenga (northern Italy). Initial symptoms included stem necrosis at the soil level and darkening of leaves. Disease was characterized by the presence of soft, watery tissues, particularly on affected leaves. As stem and foliar necrosis progressed, infected plants wilted and died. Wilt occurred within a few days on young plants. Symptomatic plants were found on 10 farms: average disease incidence in some nurseries reached 20%. Necrotic tissues became covered with a whitish mycelium that produced dark sclerotia. The diseased stem tissue was surface disinfected for 1 min in 1% NaOCl and plated on potato dextrose agar (PDA) amended with 100 ppm of streptomycin sulfate. Sclerotinia sclerotiorum (Lib.) de Bary (2) was consistently recovered from infected stem pieces. Sclerotia observed on infected plants at the soil level measured 2 to 9 × 1.5 to 7 (average 6 × 3) mm. Sclerotia produced on PDA measured 3 to 7 × 2 to 4 (average 4.4 × 3.1) mm. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 (3) and then sequenced. BLAST analysis of the 521-bp segment showed a 100% homology with the sequence of S. sclerotiorum. The nucleotide sequence has been assigned GenBank Accession No. EU627005. Pathogenicity of four isolates obtained from infected plants and used in mixture was confirmed by inoculating 10 30-day-old plants grown in 14-cm-diameter pots that were maintained in the greenhouse. Inoculum, consisting of 1-cm2 mycelial plugs excised from a 10-day-old PDA culture of each isolate, was placed on the soil surface around the base of each plant. Ten noninoculated plants served as a control. Plants were covered with a plastic bag for 4 days after inoculation. The inoculation trial was repeated once. All plants were kept at an average temperature of 20°C and watered as needed. All inoculated plants developed symptoms of leaf yellowing within 4 days, followed by the appearance of white mycelium and sclerotia and eventual wilt. Control plants remained symptomless. S. sclerotiorum was reisolated from the stems of inoculated plants. To our knowledge, this is the first report of white mold on B. officinalis in Italy as well as in Europe. The disease was recently reported in North Dakota (1). The economic importance of this disease is currently low; however, the request of borage for culinary uses is increasing.

References: (1) C. A. Bradley et al. Plant Dis. 89:208, 2005. (2) N. F. Buchwald. Den. Kgl. Veterin.er-og Landbohojskoles Aarsskrift 5:1949. (3) D. E. I. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997.
Electroencephalographic Order Pattern Analysis for the Separation of Consciousness and Unconsciousness
Authors: Jordan Denis , Stockmanns Gudrun , Kochs Eberhard F. , Pilge Stefanie , Schneider Gerhard
Published: November 2008

Background

Nonlinear electroencephalographic parameters, e.g., approximate entropy, have been suggested as measures of the hypnotic component of anesthesia. Compared with linear methods, they may detect additional information and quantify the irregularity of a dynamical system. High dimensionality of a signal and disturbances may affect these parameters and change their ability to distinguish consciousness from unconsciousness. Methods of order pattern analysis, in this investigation represented by permutation entropy, recurrence rate, and phase coupling of order recurrence plots, are suitable for any type of time series, whether deterministic or noisy. They may provide a better estimation of the hypnotic component of anesthesia than other nonlinear parameters.

Methods

The current analysis is based on electroencephalographic data from two similar clinical studies in adult patients undergoing general anesthesia with sevoflurane or propofol. The study period was from induction until patients followed command after surgery, including a reduction of the hypnotic agent after tracheal intubation until patients followed command. Prediction probability was calculated to assess the parameter's ability to separate consciousness from unconsciousness at the transition between both states.

Results

Parameters of order pattern analysis provide a prediction probability of maximal 0.85 (training study) and 0.78 (evaluation study) with frequencies from 0 to 30 Hz, and maximal 0.87 (training study) and 0.83 (evaluation study) including frequencies up to 70 Hz, both higher than 0.77 (approximate entropy).

Conclusions

Parameters of the nonlinear method order pattern analysis separate consciousness from unconsciousness and are grossly independent of high-frequency components of the electroencephalogram.
Sex Differences in the Effect of Dyspnea on Thermal Pain Threshold in Young Healthy Subjects
Authors: Nishino Takashi , Isono Shiroh , Ishikawa Teruhiko , Shinozuka Norihiro
Published: November 2008

Background

Previous study has demonstrated that dyspnea exerts inhibitory influence on pain, and empirical research supports the existence of sex differences in pain. To test the hypothesis that the inhibitory influence of dyspnea on the pain sensation may be less in females than in males, the authors investigated the sex differences in the responses of thermal pain threshold to dyspnea in healthy young subjects.

Methods

The authors measured changes in thermal pain threshold in 30 female subjects and 30 male subjects before and during dyspnea produced by a combination of hypercapnia and elastic loading, and compared the difference between males and females.

Results

The thermal pain threshold significantly increased during loaded breathing in male subjects (46.0 degrees +/- 1.3 degrees vs. 47.2 degrees +/- 1.2 degrees C; P < 0.01, baseline vs. loaded breathing), whereas no change was observed in female subjects (46.1 degrees +/- 1.3 degrees vs. 46.0 degrees +/- 1.4 degrees C; P > 0.1). No significant correlation was observed between the values of dyspneic visual analog scale and changes in thermal pain threshold. Comparison of the different phases of the menstrual cycle in female subjects also showed that there was no consistent effect of the particular phase on thermal pain threshold (45.7 degrees +/- 1.0 degrees vs. 46.1 degrees +/- 1.4 degrees C; P > 0.1, follicular phase vs. luteal phase during baseline; and 45.9 degrees +/- 1.1 degrees vs. 46.0 degrees +/- 1.7 degrees C; P > 0.1, follicular phase vs. luteal phase during loaded breathing).

Conclusion

The inhibitory influence of dyspnea on the pain sensation is less in females than in males, but the sex difference may not be explained by female reproductive hormones alone.
Gabapentin Acts within the Locus Coeruleus to Alleviate Neuropathic Pain
Authors: Hayashida Ken-ichiro , Obata Hideaki , Nakajima Kunie , Eisenach James C.
Published: November 2008

Background

Gabapentin recruits descending inhibition to produce analgesia after nerve injury, but whether this is a local action in the brainstem is unknown. The authors hypothesized that gabapentin activates noradrenergic neurons in the locus coeruleus (LC) by a local action.

Methods

Male rats underwent L5-L6 spinal nerve ligation (SNL) and received drugs by intra-LC or systemic routes for behavior testing, immunohistochemistry in the LC, and microdialysis in the spinal dorsal horn. In other studies, brainstem slices from normal and SNL animals were used for immunohistochemistry.

Results

SNL increased phosphorylated cyclic adenosine monophosphate response element binding protein (pCREB)-expressing nuclei bilaterally in the LC, and increased noradrenaline release in the spinal dorsal horn. Gabapentin, whether in isolated brainstem slices or in conscious or anesthetized animals, increased pCREB-expressing nuclei in the LC. The net increase in pCREB expression by gabapentin did not differ between normal and SNL conditions. This gabapentin-induced pCREB activation in LC neurons was abolished by an AMPA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Intra-LC-injected gabapentin reduced hypersensitivity in SNL rats in a dose-dependent manner. Both intra-LC coadministration of CNQX and intrathecal administration of the alpha2-adrenoceptor antagonist idazoxan blocked antihypersensitivity by intra-LC gabapentin. Intravenous gabapentin induced noradrenaline release in the spinal dorsal horn. The net amount of noradrenaline release by gabapentin is larger in SNL rats compared with the normal condition, although the percentage increases from the baseline were the same.

Conclusions

These results suggest that gabapentin acts directly in the brainstem via a glutamate-dependent mechanism to stimulate descending inhibition to produce antihypersensitivity after peripheral nerve injury.
γ-Aminobutyric Acid–mediated Neurotransmission in the Pontine Reticular Formation Modulates Hypnosis, Immobility, and Breathing during Isoflurane Anesthesia
Authors: Vanini Giancarlo , Watson Christopher J. , Lydic Ralph , Baghdoyan Helen A.
Published: November 2008

Background

Many general anesthetics are thought to produce a loss of wakefulness, in part, by enhancing gamma-aminobutyric acid (GABA) neurotransmission. However, GABAergic neurotransmission in the pontine reticular formation promotes wakefulness. This study tested the hypotheses that (1) relative to wakefulness, isoflurane decreases GABA levels in the pontine reticular formation; and (2) pontine reticular formation administration of drugs that increase or decrease GABA levels increases or decreases, respectively, isoflurane induction time.

Methods

To test hypothesis 1, cats (n = 5) received a craniotomy and permanent electrodes for recording the electroencephalogram and electromyogram. Dialysis samples were collected from the pontine reticular formation during isoflurane anesthesia and wakefulness. GABA levels were quantified using high-performance liquid chromatography. For hypothesis 2, rats (n = 10) were implanted with a guide cannula aimed for the pontine reticular formation. Each rat received microinjections of Ringer's (vehicle control), the GABA uptake inhibitor nipecotic acid, and the GABA synthesis inhibitor 3-mercaptopropionic acid. Rats were then anesthetized with isoflurane, and induction time was quantified as loss of righting reflex. Breathing rate was also measured.

Results

Relative to wakefulness, GABA levels were significantly decreased by isoflurane. Increased power in the electroencephalogram and decreased activity in the electromyogram caused by isoflurane covaried with pontine reticular formation GABA levels. Nipecotic acid and 3-mercaptopropionic acid significantly increased and decreased, respectively, isoflurane induction time. Nipecotic acid also increased breathing rate.

Conclusion

Decreasing pontine reticular formation GABA levels comprises one mechanism by which isoflurane causes loss of consciousness, altered cortical excitability, muscular hypotonia, and decreased respiratory rate.
On the complete integrability and linearization of nonlinear ordinary differential equations. IV. Coupled second-order equations
Authors: Chandrasekar V.K , Senthilvelan M , Lakshmanan M
Published: November 2008

Coupled second-order nonlinear differential equations are of fundamental importance in dynamics. In this part of our study on the integrability and linearization of nonlinear ordinary differential equations (ODEs), we focus our attention on the method of deriving a general solution for two coupled second-order nonlinear ODEs through the extended Prelle–Singer procedure. We describe a procedure to obtain integrating factors and the required number of integrals of motion so that the general solution follows straightforwardly from these integrals. Our method tackles both isotropic and non-isotropic cases in a systematic way. In addition to the above-mentioned method, we introduce a new method of transforming coupled second-order nonlinear ODEs into uncoupled ones. We illustrate the theory with potentially important examples.