bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-resolved triple probe investigations of a pulsed magnetron discharge
Authors: Bryant P. M. , Voronin S. A. , Bradley J. W. , Vetushka A.
Published: August 2007

Time-resolved measurements of the electron temperature Te and density ne at the centerline of a bipolar pulsed dc magnetron argon discharge were obtained using a triple probe. Two electron temperature spikes at the pulse transients were observed and are interpreted as being due to the presence of energetic electrons generated during these periods. During the off time the observed rapid decay of Te and gradual decay of ne are shown to be a consequence of enhanced plasma retention due to the magnetized electrons. The rapid rise in ne during the on time was observed to reach a maximum, coinciding with a minimum in Te (with Te decaying rapidly), probably due to enhanced ionization by the energetic electrons. Throughout the rest of the pulse period Te increased slightly whereas ne decreased due to global collisional heating of electrons with an additional energetic electron group formed during the on time. The results also show that the electron temperature and plasma density increase with decreasing duty cycle. The plasma density increased linearly with the total energy input per pulse E and increases with pressure. The electron temperature decreases towards the higher pressures and was found to be approximately independent of E. The calculated ion power flux density to a floating substrate (averaged over one pulse cycle and being proportional to the ion-to-atom arrival ratio) was found to be higher by a factor between 2 and 4 than during dc at the same discharge conditions. The power flux was also found to increase linearly with time-averaged power with the steepest rise at the lowest duty cycle. Decreasing the duty cycle and increasing the time-averaged power will lead to the rise in the ion-to-atom arrival ratio and generally improve the quality of the deposited thin films. Finally, these results show the triple probe to be a reliable and efficient method to measure the temporal evolution of the plasma parameters in the pulsed magnetron.
N-polar GaN∕AlGaN∕GaN high electron mobility transistors
Authors: Rajan Siddharth , Chini Alessandro , Wong Man Hoi , Speck James S. , Mishra Umesh K.
Published: August 2007

We describe the development of N-polar GaN-based high electron mobility transistors grown by N2 plasma-assisted molecular beam epitaxy on C-face SiC substrates. High mobility AlGaN∕GaN modulation-doped two-dimensional electron gas channels were grown, and transistors with excellent dc and small-signal performance were fabricated on these wafers. Large-signal dispersion was observed, and the trap states responsible for this were identified, and layer designs to remove the dispersive effects of these traps were demonstrated. Finally, an AlGaN-cap layer was used to reduce gate leakage in these devices, and a low-dispersion high breakdown voltage device was achieved. This detailed study of dispersion and leakage in N-polar GaN-based transistors establishes a technological base for further development of field effect devices based on N-polar III-nitrides.
High-pressure reactively sputtered HfO2: Composition, morphology, and optical properties
Authors: Toledano-Luque M. , San Andrés E. , del Prado A. , Mártil I. , Lucía M. L. , González-Díaz G. , Martínez F. L. , Bohne W. , Röhrich J. , Strub E.
Published: August 2007

Hafnium oxide films were deposited by high pressure reactive sputtering using different deposition pressures and times. The composition, morphology, and optical properties of the films, together with the sputtering process growth kinetics were investigated using heavy ion elastic recoil detection analysis, Fourier transform infrared spectroscopy, ultraviolet-visible-near infrared spectroscopy, x-ray diffraction, and transmission electron microscopy. The films showed a monoclinic polycrystalline structure, with a grain size depending on the deposition pressure. All films were slightly oxygen rich with respect to stoichiometric HfO2 and presented a significant amount of hydrogen (up to 6at.%), which is attributed to the high affinity for moisture of the HfO2 films. The absorption coefficient was fitted to the Tauc law, obtaining a band gap value of 5.54eV. It was found that the growth rate of the HfO2 films depends on the deposition pressure (P) as P−1.75. This dependence is explained by a diffusion model of the thermalized atoms in high-pressure sputtering. Additionally, the formation of an interfacial silicon oxide layer when the films were grown on silicon was observed, with a minimum thickness for deposition pressures around 1.2mbars. This interfacial layer was formed mainly during the initial stages of the deposition process, with only a slight increase in thickness afterwards. These results are explained by the oxidizing action of the oxygen plasma and the diffusion of oxygen radicals and hydroxyl groups through the polycrystalline HfO2 film. Finally, the dielectric properties of the HfO2∕SiO2 stacks were studied by means of conductance and capacitance measurements on Al∕HfO2∕SiO2∕Si devices as a function of gate voltage and ac frequency signal.
Room-temperature spin-oriented photocurrent under near-infrared irradiation and comparison of optical means with Shubnikov de-Haas measurements in AlxGa1−xN∕GaN heterostructures
Authors: Tang Y. Q. , Shen B. , He X. W. , Han K. , Tang N. , Chen W. H. , Yang Z. J. , Zhang G. Y. , Chen Y. H. , Tang C. G. , Wang Z. G. , Cho K. S. , Chen Y. F.
Published: August 2007

The admixture of linear and circular photogalvanic effects and (CPGEs) in AlxGa1−xN∕GaN heterostructures has been investigated quantitatively by near-infrared irradiation at room temperature. The spin-based photocurrent that the authors have observed solidly indicates the sizable spin-orbital interaction of the two-dimensional electron gas in the heterostructures. Further analysis shows consistency between studies by optical and magnetic (Shubnikov de-Haas) measurements on the spin-orbital coupling effects among different AlxGa1−xN∕GaN heterostructures, indicating that the CPGE measurement is a good way to investigate the spin splitting and the spin polarization in semiconductors.
Dielectric properties of upright carbon fiber filled poly(vinylidene fluoride) composite with low percolation threshold and weak temperature dependence
Authors: Dang Zhi-Min , Wu Jin-Ping , Xu Hai-Ping , Yao Sheng-Hong , Jiang Mei-Juan , Bai Jinbo
Published: August 2007

Upright carbon fiber (CF) filled ferroelectric poly(vinylidene fluoride) (PVDF) composites were prepared via a simple blending and hot-molding technique. The dielectric properties of the CF/PVDF composites as a function of the volume fraction of CF, the temperature, and the frequency were studied. The dielectric constants decrease slowly with increasing frequency and rise gradually with increasing CF contents in the composites. As the volume fraction of the CF is up to 0.074, an abrupt increase in the dielectric constant occurs, which is attributed to the formation of the conductive network in the matrix. The percolation theory, the microcapacitor model, and the simple concept of polarization in the capacitors are employed to explain these experimental results.
Effect of annealing on the magnetic properties of Gd focused ion beam implanted GaN
Authors: Khaderbad M. A. , Dhar S. , Pérez L. , Ploog K. H. , Melnikov A. , Wieck A. D.
Published: August 2007

The authors have studied the effect of annealing on the magnetic and the structural properties of Gd focused ion beam implanted GaN samples. Molecular beam epitaxy grown GaN layers, which were implanted with 300keV Gd3+ ions at room temperature at doses 2.4×1011 and 1.0×1015cm−2, are rapid thermally annealed in flowing N2 gas up to 900°C for 30s. X-ray diffraction results indicate the presence of Ga and N interstitials in the implanted layers. Their densities are also found to reduce upon annealing. At the same time, magnetic measurements on these samples clearly show a reduction in the saturation magnetization as a result of the annealing for the lowest Gd incorporated sample, while in the highest Gd incorporated sample it does not change. These findings suggest that Gd might be inducing magnetic moment in Ga and/or N interstitials in giving rise to an effective colossal magnetic moment of Gd and the associated ferromagnetism observed in Gd:GaN.
Determining parameter sets for low-frequency-oscillation-free operation of Hall thruster
Authors: Tamida Taichiro , Nakagawa Takafumi , Suga Ikuro , Osuga Hiroyuki , Ozaki Toshiyuki , Matsui Katsuaki
Published: August 2007

We performed a theoretical and experimental study of low-frequency oscillation in a Hall thruster. The oscillation phenomenon depends on various external control parameters. However, we found that such dependence can be observed very clearly using certain expressions, which are combinations of external control parameters. Using these expressions, one can observe the oscillation strength and oscillation mode for a given set of external control parameters. We considered that low-frequency oscillation can be essentially suppressed by a method of determining parameter sets. The method of determining the parameter sets is very important for Hall thruster design and control; in particular, it makes it easy to manage electromagnetic compatibility with the other equipments in a satellite, using a power supply control.
Laser assisted field induced oxide nanopatterning of hydrogen passivated silicon surfaces
Authors: Pingree L. S. C. , Schmitz M. J. , Kramer D. E. , Hersam M. C.
Published: August 2007

Field induced oxide (FIO) nanopatterning of hydrogen passivated silicon surfaces with an atomic force microscope (AFM) has been controlled by laser irradiation. Specifically, local oxidation on H:Si(111) surfaces can be fully suppressed or activated by toggling a laser that is illuminating a lightly doped silicon AFM cantilever. The nanopatterning mechanism is attributed to the control of the free carrier concentration in the AFM probe by the laser. When the laser is toggled off, charge injection is terminated, thus eliminating the electrochemical reactions required for oxide formation. Laser assisted FIO provides an alternative and flexible means for controlling oxide nanopatterning.
Observation of type-I and type-II excitons in strained Si∕SiGe quantum-well structures
Authors: Wang K. Y. , Huang W. P. , Cheng H. H. , Sun G. , Soref R. A. , Nicholas R. J. , Suen Y. W.
Published: August 2007

The authors report photoluminescence (PL) measurement on a series of Si∕SiGe quantum-well structures that had different internal strain distributions. When each sample was placed in a high magnetic field, the field-dependent energy shift of the relevant PL peaks revealed either type-I or type-II exciton formation depending on the strain distribution. This observation is in agreement with theoretical modeling. The present investigation shows that type-I band alignment—desired for electroluminescent devices—can be achieved by strain engineering.
Equations for the motion of relativistic torus in the Minkowski space R1+n
Authors: Huang Shou-Jun , Kong De-Xing
Published: August 2007

In this paper we derive the equations for the motion of relativistic torus in the Minkowski space R1+n (n⩾3). This kind of equations also describes the three-dimensional timelike extremal submanifolds in the Minkowski space R1+n. We show that these equations can be reduced to a (1+2)-dimensional quasilinear symmetric hyperbolic system and the system possesses some interesting properties such as nonstrict hyperbolicity, constant multiplicity of eigenvalues, linear degeneracy of all characteristic fields, strong null condition, etc. We also find and prove an interesting fact that all plane wave solutions to these equations are lightlike extremal submanifolds and vice versa except for a type of special solution.
Photodetector with artificial atoms of silicon
Authors: Hu Shu-Fen , Liao Ting-Wei , Huang Chao-Yuan
Published: August 2007

The authors demonstrate a potential application of quantum dots for the detection of photons, showing that the Coulomb interaction resulting from the capture of photoexcited carriers by quantum dots produces a detectable change in the source-drain resistance of the transistor. This quantum effect is more pronounced with higher illumination, displaying staircase quantum steps with ΔV=4mV on the I-V characteristics at room temperature, implying that the photocurrent is increased as the light intensity is increased. The responsitivity of device is R∼3.98×106A∕W for Vd=0.18V, and external quantum efficiency is more than 8.6%.
Integrating optics and microfluidics for time-correlated single-photon counting in lab-on-a-chip devices
Authors: Cleary A. , Glidle A. , Laybourn P. J. R. , García-Blanco S. , Pellegrini S. , Helfter C. , Buller G. S. , Aitchison J. S. , Cooper J. M.
Published: August 2007

The authors describe the integration of low-loss optical waveguides with lab-on-a-chip structures to produce an integrated optical-microfluidic platform for time-correlated single-photon counting of fluorescent molecules. Waveguides were fabricated using electron beam densification of planar silica on silicon, eliminating any requirement for depositing upper cladding silica layers. Microfluidic channels were dry etched directly through the waveguides and the device was sealed using a poly(dimethylsiloxane) gasket. Time-resolved fluorescence lifetime measurements of the fluorophore nile blue were used as a model system to demonstrate the operation of the microfluidic device, with dye concentrations as low as 1.5nM (equivalent to <6000molecules) being measured.
Amplification of spin-current polarization
Authors: Saha D. , Holub M. , Bhattacharya P.
Published: August 2007

A ferromagnet/semiconductor based electrically controlled spin-current amplifier using a dual-drain nonlocal lateral spin valve is demonstrated. The spin polarization injected by the source into the channel is amplified at the second drain contact. An amplified current spin polarization of 100% is measured. The controlled variation of amplifier gain with bias is also demonstrated. The observations are explained in the framework of the spin drift-diffusion model.
Light controlled spin polarization in asymmetric n-type resonant tunneling diode
Authors: dos Santos L. F. , Galvão Gobato Y. , Marques G. E. , Brasil M. J. S. P. , Henini M. , Airey R.
Published: August 2007

The authors have observed a strong dependence of the circular polarization degree from the quantum well emission in an asymmetric n-type GaAs∕AlAs∕AlGaAs resonant tunneling diode on both the laser excitation intensity and the applied bias voltage. The sign of the circular polarization can be reversed by increasing the light excitation intensity when the structure is biased with voltages slightly larger than the first electron resonance. The variation of polarization is associated with a large density of photogenerated holes accumulated in the quantum well, which is enhanced due to the asymmetry of the structure.
Quenching of surface-exciton emission from ZnO nanocombs by plasma immersion ion implantation
Authors: Yang Y. , Tay B. K. , Sun X. W. , Sze J. Y. , Han Z. J. , Wang J. X. , Zhang X. H. , Li Y. B. , Zhang S.
Published: August 2007

Surface modification of ZnO nanocombs was performed through a Ti plasma immersion ion implantation (PIII) with low bias voltages ranging from 0to5kV to quench surface-originated exciton emission. The ion energy dependent surface modification on ZnO was investigated using transmission electron microscopy and temperature-dependent photoluminescence (PL). The surface exciton (SX) was clearly identified for the as-grown sample at 4.5K, and complete quenching was observed for sample treated with 5kV PIII due to surface state passivation. The SX related surface states were located within 5nm in depth from the surface corresponding to the implantation depth of 5kV PIII. Room-temperature PL enhancement of these surface-modified ZnO nanocombs was observed and discussed. The results show that PIII can become a viable technique for nanostructure surface passivation.
Miniaturized negative permeability materials
Authors: Alici Kamil Boratay , Bilotti Filiberto , Vegni Lucio , Ozbay Ekmel
Published: August 2007

Experimental and numerical studies of μ-negative (MNG) materials such as multisplit ring resonators (MSRRs) and spiral resonators (SRs) are presented. The resonance frequency of the structures is determined by the transmission measurements and minimum electrical size of λ0∕17 for the MSRRs and of λ0∕82 for the SRs observed. These MNG materials can be easily produced by the well developed printed circuit board and optical lithography techniques. They are promising elements for the development of high resolution metamaterial lenses and electrically small antennas.
Effect of facet angle on effective facet reflectivity and operating characteristics of quantum dot edge emitting lasers and superluminescent light-emitting diodes
Authors: Zhang Z. Y. , Luxmoore I. J. , Jin C. Y. , Liu H. Y. , Jiang Q. , Groom K. M. , Childs D. T. , Hopkinson M. , Cullis A. G. , Hogg R. A.
Published: August 2007

The authors report the creation of low reflectivity angled facets by focused-ion-beam postfabrication etching. A method to directly measure the effective facet reflectivity of such facets, utilizing gain saturation effects in the quantum dots is described. The reflectivities of the angled facets are shown to decrease by increasing the facet angle from 0° to 15°. With a reflectivity of <1×10−6 obtained for a facet with a 15° angle, allowing quantum dot superluminescent light-emitting diodes to be fabricated. The use of different angled facets to control the emission wavelength of both quantum dot lasers and superluminescent light-emitting diodes is outlined.
Achieving ambipolar vertical organic transistors via nanoscale interface modification
Authors: Li Sheng-Han , Xu Zheng , Ma Liping , Chu Chih-Wei , Yang Yang
Published: August 2007

Organic field-effect transistors have been the subject of much recent inquiry due to their unique properties. Here, the authors report an ambipolar vertical organic field-effect transistor, which consists of a capacitor cell vertically stacked with an organic active cell, separated by a thin source electrode. By inserting a nanoscale transition-metal-oxide layer at the source/organic interface, the authors fabricated the organic ambipolar transistors with low working voltage and high current output. The thin transition-metal oxide and partial oxidization metal grains form a unique nanostructure that balances the injection barrier height of two types of carriers at the source/organic contact.
Intravenous immunoglobulin (IVIG) protects the brain against experimental stroke by preventing complement-mediated neuronal cell death
Authors: Arumugam Thiruma V. , Tang Sung-Chun , Lathia Justin D. , Cheng Aiwu , Mughal Mohamed R. , Chigurupati Srinivasulu , Magnus Tim , Chan Sic L. , Jo Dong-Gyu , Ouyang Xin , Fairlie David P. , Granger Daniel N. , Vortmeyer Alexander , Basta Milan , Mattson Mark P.
Published: August 2007

Stroke is among the three leading causes of death worldwide and the most frequent cause of permanent disability. Brain ischemia induces an inflammatory response involving activated complement fragments. Here we show that i.v. Ig (IVIG) treatment, which scavenges complement fragments, protects brain cells against the deleterious effects of experimental ischemia and reperfusion (I/R) and prevents I/R-induced mortality in mice. Animals administered IVIG either 30 min before ischemia or after 3 h of reperfusion exhibited a 50–60% reduction of brain infarct size and a 2- to 3-fold improvement of the functional outcome. Even a single low dose of IVIG given after stroke was effective. IVIG was protective in the nonreperfusion model of murine stroke as well and did not exert any peripheral effects. Human IgG as well as intrinsic murine C3 levels were significantly higher in the infarcted brain region compared with the noninjured side, and their physical association was demonstrated by immuno-coprecipitation. C5-deficient mice were significantly protected from I/R injury compared with their wild-type littermates. Exposure of cultured neurons to oxygen/glucose deprivation resulted in increased levels of C3 associated with activation of caspase 3, a marker of apoptosis; both signals were attenuated with IVIG treatment. Our data suggest a major role for complement-mediated cell death in ischemic brain injury and the prospect of using IVIG in relatively low doses as an interventional therapy for stroke.
Ground squirrels use an infrared signal to deter rattlesnake predation
Authors: Rundus Aaron S. , Owings Donald H. , Joshi Sanjay S. , Chinn Erin , Giannini Nicolas
Published: August 2007

The evolution of communicative signals involves a major hurdle; signals need to effectively stimulate the sensory systems of their targets. Therefore, sensory specializations of target animals are important sources of selection on signal structure. Here we report the discovery of an animal signal that uses a previously unknown communicative modality, infrared radiation or “radiant heat,” which capitalizes on the infrared sensory capabilities of the signal's target. California ground squirrels (Spermophilus beecheyi) add an infrared component to their snake-directed tail-flagging signals when confronting infrared-sensitive rattlesnakes (Crotalus oreganus), but tail flag without augmenting infrared emission when confronting infrared-insensitive gopher snakes (Pituophis melanoleucus). Experimental playbacks with a biorobotic squirrel model reveal this signal's communicative function. When the infrared component was added to the tail flagging display of the robotic models, rattlesnakes exhibited a greater shift from predatory to defensive behavior than during control trials in which tail flagging included no infrared component. These findings provide exceptionally strong support for the hypothesis that the sensory systems of signal targets should, in general, channel the evolution of signal structure. Furthermore, the discovery of previously undescribed signaling modalities such as infrared radiation should encourage us to overcome our own human-centered sensory biases and more fully examine the form and diversity of signals in the repertoires of many animal species.
Structural insights into the interaction of the evolutionarily conserved ZPR1 domain tandem with eukaryotic EF1A, receptors, and SMN complexes
Authors: Mishra Ashwini K. , Gangwani Laxman , Davis Roger J. , Lambright David G.
Published: August 2007

Eukaryotic genomes encode a zinc finger protein (ZPR1) with tandem ZPR1 domains. In response to growth stimuli, ZPR1 assembles into complexes with eukaryotic translation elongation factor 1A (eEF1A) and the survival motor neurons protein. To gain insight into the structural mechanisms underlying the essential function of ZPR1 in diverse organisms, we determined the crystal structure of a ZPR1 domain tandem and characterized the interaction with eEF1A. The ZPR1 domain consists of an elongation initiation factor 2-like zinc finger and a double-stranded β helix with a helical hairpin insertion. ZPR1 binds preferentially to GDP-bound eEF1A but does not directly influence the kinetics of nucleotide exchange or GTP hydrolysis. However, ZPR1 efficiently displaces the exchange factor eEF1Bα from preformed nucleotide-free complexes, suggesting that it may function as a negative regulator of eEF1A activation. Structure-based mutational and complementation analyses reveal a conserved binding epitope for eEF1A that is required for normal cell growth, proliferation, and cell cycle progression. Structural differences between the ZPR1 domains contribute to the observed functional divergence and provide evidence for distinct modalities of interaction with eEF1A and survival motor neuron complexes.
A diapause pathway underlies the gyne phenotype inPolisteswasps, revealing an evolutionary route to caste-containing insect societies
Authors: Hunt James H. , Kensinger Bart J. , Kossuth Jessica A. , Henshaw Michael T. , Norberg Kari , Wolschin Florian , Amdam Gro V.
Published: August 2007

Colonies of social wasps, ants, and bees are characterized by the production of two phenotypes of female offspring, workers that remain at their natal nest and nonworkers that are potential colony reproductives of the next generation. The phenotype difference includes morphology and is fixed during larval development in ants, honey bees, and some social wasps, all of which represent an advanced state of sociality. Paper wasps (Polistes) lack morphological castes and are thought to more closely resemble an ancestral state of sociality wherein the phenotype difference between workers and nonworkers is established only during adult life. We address an alternative hypothesis: a bias toward the potential reproductive (gyne) phenotype amongPolistesfemale offspring occurs during larval development and is based on a facultatively expressed ancestral life history trait: diapause. We show that two signatures of diapause (extended maturation time and enhanced synthesis and sequestration of a hexameric storage protein) characterize the development of gyne offspring inPolistes metricus. Hexameric storage proteins are implicated in silencing juvenile hormone signaling, which is a prerequisite for diapause. Diverging hexamerin protein dynamics driven by changes in larval provisioning levels thereby provide one possible mechanism that can cause an adaptive shift in phenotype bias during thePolistescolony cycle. This ontogenetic basis for alternative female phenotypes inPolisteschallenges the view that workers and gynes represent behavior options equally available to every female offspring, and it exemplifies how social insect castes can evolve from casteless lineages.
Diploid apomicts of the
Boechera holboellii
complex display large-scale chromosome substitutions and aberrant chromosomes
Authors: Kantama Laksana , Sharbel Timothy F. , Schranz M. Eric , Mitchell-Olds Thomas , de Vries Sacco , de Jong Hans
Published: August 2007

We conducted a cytogenetic study of sexual lines of
Boechera stricta
and
Boechera holboellii
(2
n
= 14) and seven diploid apomictic accessions of their interspecific hybrid
Boechera divaricarpa
and
B. holboellii
(2
n
= 14 or 15). By studying chromosome morphology, rDNA repeats, genome painting, male meiosis, pollen morphology, and flow-cytometry seed screens, we revealed an unexpected plethora of chromosome forms, pairing behavior, and hybrid composition in all apomictic lines. Genome painting demonstrated that the apomicts are alloploid with variable numbers of
B. stricta
and
B. holboellii
-like chromosomes. We assume that large-scale homeologous chromosome substitutions took place in the apomictic hybrids that resulted from recurrent diploid–polyploid transitions through restitutional meiosis and polyploidy–diploid transitions through reductional meiosis. A second peculiarity was the presence of a largely heterochromatic chromosome (
Het
) in all apomictic accessions (2
n
= 14 and 15) and an additional smaller chromosome (
Del
) in the aneuploids (2
n
= 15). Both chromosomes share repetitive pericentromere repeats with those from the sexual
B. stricta
, suggesting that they originated from this species. Pairing and behavior at meiosis I of the
Het
share features with both Y and B chromosomes and suggest that the
Del
arose from a translocation event or homeologous recombination between a
B. holboellii
(or related taxon) and a
B. stricta
chromosome. Based on its presence exclusively in apomictic accessions, we propose that the
Het
chromosome plays a role in the genetic control of apomixis.
“For the Glory of Romanians”: Orthodoxy and Nationalism in Greater Romania, 1918–1945*
Authors: Leustean Lucian N.
Published: August 2007

The relationship between Orthodox Christianity and national identity has been one of the most contended issues in modern nationalism. The dominant religion in the Balkans, Orthodoxy has transported the identity of ethnic groups into the modern era and political leaders have employed religious institutions according to their own political agendas in the construction of “imagined communities.” Orthodoxy has a particular perception of the political field. Based on the concept ofsymphonia,which dates back to the Byzantine Empire, the Church claims that religious and political offices are equal and have similar responsibilities. Religious and political rulers have the mission to guide the people and the Church and state should collaborate harmoniously in fostering identity. Political leaders refer to the nationalist discourse of the Church in order to induce national cohesion. From this perspective, the relationship between religion and the construction of the nation in the Orthodox space differs from that in the Catholic or Protestant world where Churches are supranational or sub-national institutions.
The Use of Diagnostic Frequency Continuous Ultrasound to Improve Microcirculatory Function After Ischemia–Reperfusion Injury
Authors: Hightower C. Makena , Intaglietta Marcos
Published: August 2007

ABSTRACT

Objective: Damage to the circulatory system resulting from ischemia–reperfusion injury (I/R injury) occurs during heart attacks and hemorrhagic shock. The authors report a method for mitigating microcirculatory injury, using diagnostic frequency continuous‐mode ultrasound and how effects are influenced by nitric oxide production impairment.

Methods: Five groups of hamsters were studied using the dorsal skin fold window chamber: (1) I/R; (2) I/R + ultrasound during ischemia; (3) I/R + ultrasound after ischemia; (4) I/R + Nω‐nitro‐l‐arginine methyl ester (l‐NAME); and (5) I/R + l‐NAME + ultrasound. Functional capillary density (FCD) and microvascular diameter, flow velocity, and flow were monitored. During the exposures 2.49 MHz continuous ultrasound was used.

Results: Significant improvements in animals exposed to ultrasound after ischemia were found at 24 h of reperfusion in FCD, arteriolar diameter, and arteriolar and venular flow velocity and flow. Animals exposed to ultrasound during ischemia showed significantly improved FCD. l‐NAME treatment reduced the improvement of microvascular function, compared to animals exposed after ischemia.

Conclusions: The use of continuous‐mode diagnostic frequency ultrasound is beneficial in preventing long‐term ischemia–reperfusion effects in the microcirculation as shown by the return of microvascular parameters to baseline values, an effect not attained in the absence of ultrasound treatment. The effects may be in part due to the production of nitric oxide consequent to locally induced shear stress effects by ultrasound exposure.
Representation: The Problem for Structuralism
Authors: van Fraassen Bas C.
Published: August 2007

What does it mean to embed the phenomena in an abstract structure? Or to represent them by doing so? The semantic view of theories runs into a severe problem if these notions are construed either naively, in a metaphysical way, or too closely on the pattern of the earlier syntactic view. Constructive empiricism and structural realism will then share those difficulties. The problem will be posed as in Reichenbach's The Theory of Relativity and A Priori Knowledge, and realist reactions will be examined, but they will be argued to dissolve upon scrutiny.
Comparativist Philosophy of Science and Population Viability Assessment in Biology: Helping Resolve Scientific Controversy
Authors: Shrader-Frechette Kristin
Published: August 2007

Comparing alternative scientific theories obviously is relevant to theory assessment, but are comparativists (like Laudan) correct when they also make it necessary? This paper argues that they are not. Defining rationality solely in terms of theories’ comparative problem-solving strengths, comparativist philosophers of science like Laudan subscribe to what I call the irrelevance claim (IC) and the necessity claim (NC). According to IC, a scientific theory's being well or poorly confirmed is “irrelevant” to its acceptance; NC is the claim that “all evaluations of research traditions and theories must be made within a comparative context,” how any theory “compares with its competitors” (Laudan 1977, 21, 120). Using current competing theories (T1 and T2) of population viability assessment (PVA) for the Florida panther, the paper investigates IC/NC. In part because dominant T2 panther biologists accept IC/NC (which T1 theorists reject), the paper argues that they appear both to have accepted flawed T2 and to have contributed to flawed panther science and policy. Correcting Laudan's Comparativist Philosophy of Science (LCPS), underlying the T1-versus-T2 debate, thus may hold promise for helping resolve both the scientific and policy controversy over panther PVA.
Groups in Mind
Authors: Hilbert David , Huggett Nick
Published: August 2007

Both Henri Poincaré and (more recently) Roger Shepard have argued that the geometry and topology of physical space are internalized by the mind in the form, not (or not only) of a Euclidean manifold, but in terms of the group of rigid Euclidean transformations. Since this issue can have bearing on various metaphysical and epistemological questions, we explore the different reasons they offer for holding this view. In this context, we show how most commentators misunderstand Poincaré's ‘heated sphere/plate’ model and introduce Shepard's ideas to the philosophy of science community.
Hydrodynamics versus Molecular Dynamics: Intertheory Relations in Condensed Matter Physics
Authors: Batterman Robert W.
Published: August 2007

This paper considers the relationship between continuum hydrodynamics and discrete molecular dynamics in the context of explaining the behavior of breaking droplets. It is argued that the idealization of a fluid as a continuum is actually essential for a full explanation of the drop breaking phenomenon and that, therefore, the less “fundamental,” emergent hydrodynamical theory plays an ineliminable role in our understanding.
Decisions, Decisions: Why Thomas Hunt Morgan Was Not the “Father” of Evo-Devo
Authors: Schwartz Jeffrey H.
Published: August 2007

Although the construction of neo-Darwinism grew out of Thomas Hunt Morgan's melding of Darwinism and Mendelism, his evidence did not soley support a model of gradual change. To the contrary, he was confronted with observations that could have led him to a more “evo-devo” understanding of the emergence of novel features. Indeed, since Morgan was an embryologist before he became a fruit-fly geneticist, one would have predicted that the combination of these two lines of research would have resulted in early formulations of concepts relevant to evolutionary developmental biology. It is thus of interest to review Morgan's thought processes and arguments for at first rejecting both Darwinism and Mendelism, and then for later dismissing data that would have yielded a model of rapid morphological change in favor of a model of change based on the accumulation of minor mutations and their morphological consequences.
Radical Probabilism Revisited
Authors: Zynda Lyle
Published: August 2007

In this essay, I analyze and critique Richard Jeffrey's radical probabilism. The basic theses defining it are examined, particularly the idea that probabilistic coherence involves a kind of “consistency.” The main challenges to Jeffrey's view are (1) that there is an inconsistency between regarding probabilities as subjective and some probabilistic judgments as better than others, and (2) that decision theory so conceived has no normative import. I argue that both of these challenges can be met.
The Larkin Clubs of Ten: Consumer Buying Clubs and Mail-Order Commerce, 1890–1940
Authors: Stanger Howard R.
Published: August 2007

The direct selling industry has a long history, with roots snaking back to the nineteenth-century “Yankee peddlers” who roamed the countryside selling tools, teas, and liniments door-to-door. Its reputation has suffered from the prevalence of misleading and illegal schemes such as pyramids, which generate income by paying money or other compensation solely for the act of recruiting, charge high entrance fees, and sell products of questionable value. Nonetheless, some advocates note that direct sales work, which often involves family and flexible working hours, has provided an excellent alternative to the traditional bureaucratic employment relationship that has historically been less receptive to women.
How does a generalist seabird species use its marine habitat? The case of the kelp gull in a coastal upwelling area of the Humboldt Current
Authors: Villablanca Roberto , Luna-Jorquera Guillermo , Marín Victor H. , Garthe Stefan , Simeone Alejandro
Published: August 2007

Villablanca, R., Luna-Jorquera, G., Marín, V. H., Garthe, S., and Simeone, A. 2007. How does a generalist seabird species use its marine habitat? The case of the kelp gull in a coastal upwelling area of the Humboldt Current. – ICES Journal of Marine Science, 64: 1348–1355. The distribution of kelp gulls (Larus dominicanus) was studied by ship-based transect counts in the SE Pacific Ocean off Chile, South America. Some 96–98% of the kelp gulls were in a band less than 20 km from the coast, mainly near the breeding colony on Pájaros Island and the City of Coquimbo. Abundance did not change significantly among years, but was influenced significantly by distance to land. Principal component analysis yielded two components that jointly explain 53% of the standardized variance. The first (explaining 36% of the variance) includes distance to the nearest coast and water depth, the second (17%) associates with the presence of fishing vessels. The results suggest that the stability of the summer distribution of kelp gulls is generated by the large and semi-permanent offer of food at fish markets and city sewage works, as well as the location of the breeding colonies. Further analysis on other temporal scales (seasonal, decadal) associated with reproductive or non-reproductive changes within the population and/or ENSO cycles will be necessary to confirm the multiscale stability of the pattern described.
A Rap GTPase interactor, RADIL, mediates migration of neural crest precursors
Authors: Smolen Gromoslaw A. , Schott Benjamin J. , Stewart Rodney A. , Diederichs Sven , Muir Beth , Provencher Heather L. , Look A. Thomas , Sgroi Dennis C. , Peterson Randall T. , Haber Daniel A.
Published: August 2007

The neural crest (NC) is a highly motile cell population that gives rise to multiple tissue lineages during vertebrate embryogenesis. Here, we identify a novel effector of the small GTPase Rap, called RADIL, and show that it is required for cell adhesion and migration. Knockdown of radil in the zebrafish model results in multiple defects in NC-derived lineages such as cartilage, pigment cells, and enteric neurons. We specifically show that these defects are primarily due to the diminished migratory capacity of NC cells. The identification of RADIL as a regulator of NC migration defines a role for the Rap pathway in this process.
Transcriptional Profiling ofhigh pigment-2dgTomato Mutant Links Early Fruit Plastid Biogenesis with Its Overproduction of Phytonutrients
Authors: Kolotilin Igor , Koltai Hinanit , Tadmor Yaakov , Bar-Or Carmiya , Reuveni Moshe , Meir Ayala , Nahon Sahadia , Shlomo Haviva , Chen Lea , Levin Ilan
Published: August 2007

Phenotypes of the tomato (Solanum lycopersicum) high pigment-2dg (hp-2dg) and hp-2j mutants are caused by lesions in the gene encoding DEETIOLATED1, a negative regulator of light signaling. Homozygous hp-2dg and hp-2j plants display a plethora of distinctive developmental and metabolic phenotypes in comparison to their normal isogenic counterparts. These mutants are, however, best known for the increased levels of carotenoids, primarily lycopene, and other plastid-accumulating functional metabolites. In this study we analyzed the transcriptional alterations in mature-green, breaker, and early red fruits of hp-2dg/hp-2dg plants in relation to their normal counterparts using microarray technology. Results show that a large portion of the genes that are affected by hp-2dg mutation display a tendency for up- rather than down-regulation. Ontology assignment of these differentially regulated transcripts revealed a consistent up-regulation of transcripts related to chloroplast biogenesis and photosynthesis in hp-2dg mutants throughout fruit ripening. A tendency of up-regulation was also observed in structural genes involved in phytonutrient biosynthesis. However, this up-regulation was not as consistent, positioning plastid biogenesis as an important determinant of phytonutrient overproduction in hp-2dg and possibly other hp mutant fruits. Microscopic observations revealed a highly significant increase in chloroplast size and number in pericarp cells of mature-green hp-2dg/hp-2dg and hp-2j/hp-2j fruits in comparison to their normal counterparts. This increase could be observed from early stages of fruit development. Therefore, the molecular trigger that drives phytonutrient overproduction in hp-2dg and hp-2j mutant fruits should be initially traced at these early stages.
Genetic and Molecular Regulation by DELLA Proteins of Trichome Development in Arabidopsis
Authors: Gan Yinbo , Yu Hao , Peng Jinrong , Broun Pierre
Published: August 2007

Gibberellins (GA) are known to influence phase change in Arabidopsis (Arabidopsis thaliana) as well as the development of trichomes, which are faithful epidermal markers of shoot maturation. They modulate these developmental programs in part by antagonizing DELLA repressors of growth, GIBBERELLIC ACID INSENSITIVE (GAI) and REPRESSOR OF ga1-3 (RGA). In this study, we have probed the relative roles played by RGA, GAI, and two homologs, RGA-LIKE1 (RGL1) and RGL2, in these processes and investigated molecular mechanisms through which they influence epidermal differentiation. We found that the DELLAs act collectively to regulate trichome initiation on all aerial organs and that the onset of their activity is accompanied by the repression of most genes known to regulate trichome production. These effects are consistent with the results of genetic analysis, which conclusively place theses genes downstream of the DELLAs. We find that repression of trichome regulatory genes is rapid, but involves an indirect, rather than a direct, molecular mechanism, which requires de novo protein synthesis. DELLA activity also influences postinitiation events and we show that GAI is a major repressor of trichome branching, a role in which it is antagonized by RGL1 and RGL2. Finally, we report that, in contrast to most other effects, the repression by GA applications of flower trichome initiation is not dependent on RGA, GAI, RGL1, or RGL2. In summary, our data show that DELLA proteins are central to trichome development in Arabidopsis and that their effect can be largely explained by their transcriptional influence on trichome initiation activators.
Golgi Regeneration after Brefeldin A Treatment in BY-2 Cells Entails Stack Enlargement and Cisternal Growth followed by Division
Authors: Langhans Markus , Hawes Chris , Hillmer Stefan , Hummel Eric , Robinson David G.
Published: August 2007

Brefeldin A (BFA) treatment stops secretion and leads to the resorption of much of the Golgi apparatus into the endoplasmic reticulum. This effect is reversible upon washing out the drug, providing a situation for studying Golgi biogenesis. In this investigation Golgi regeneration in synchronized tobacco BY-2 cells was followed by electron microscopy and by the immunofluorescence detection of ARF1, which localizes to the rims of Golgi cisternae and serves as an indicator of COPI vesiculation. Beginning as clusters of vesicles that are COPI positive, mini-Golgi stacks first become recognizable 60 min after BFA washout. They continue to increase in terms of numbers and length of cisternae for a further 90 min before overshooting the size of control Golgi stacks. As a result, increasing numbers of dividing Golgi stacks were observed 120 min after BFA washout. BFA-regeneration experiments performed on cells treated with BFA (10 μg mL−1) for only short periods (30–45 min) showed that the formation of ER-Golgi hybrid structures, once initiated by BFA treatment, is an irreversible process, the further incorporation of Golgi membranes into the ER continuing during a subsequent drug washout. Application of the protein kinase A inhibitor H-89, which effectively blocks the reassembly of the Golgi apparatus in mammalian cells, also prevented stack regeneration in BY-2 cells, but only at very high, almost toxic concentrations (>200 μ  m). Our data suggest that under normal conditions mitosis-related Golgi stack duplication may likely occur via cisternal growth followed by fission.
Yeast-Plant Coupled Vector System for Identification of Nuclear Proteins
Authors: Zaltsman Adi , Yi Bu-Young , Krichevsky Alexander , Gafni Yedidya , Citovsky Vitaly
Published: August 2007

Nuclear proteins are involved in many critical biological processes within plant cells and, therefore, are in the focus of studies that usually begin with demonstrating that the protein of interest indeed exhibits nuclear localization. Thus, studies of plant nuclear proteins would be facilitated by a convenient experimental system for identification of proteins that are actively imported into the cell nucleus and visualization of their nuclear accumulation in vivo. To this end, we developed a system of vectors that allows screening for cDNAs coding for nuclear proteins in a simple genetic assay in yeast cells, and verification of nuclear accumulation in planta following one-step transfer and autofluorescent tagging of the identified clones into a multiple cloning site-compatible and reading frame-compatible plant expression vector. In a recommended third experimental step, the plant expression cassette containing the identified clone can be transferred, also by a one-step cloning, into a binary multigene expression vector for transient or stable coexpression with any other proteins.
Magnaporthe grisea Cutinase2 Mediates Appressorium Differentiation and Host Penetration and Is Required for Full Virulence
Authors: Skamnioti Pari , Gurr Sarah J.
Published: August 2007

The rice blast fungus Magnaporthe grisea infects its host by forming a specialized infection structure, the appressorium, on the plant leaf. The enormous turgor pressure generated within the appressorium drives the emerging penetration peg forcefully through the plant cuticle. Hitherto, the involvement of cutinase(s) in this process has remained unproven. We identified a specific M. grisea cutinase, CUT2, whose expression is dramatically upregulated during appressorium maturation and penetration. The cut2 mutant has reduced extracellular cutin-degrading and Ser esterase activity, when grown on cutin as the sole carbon source, compared with the wild-type strain. The cut2 mutant strain is severely less pathogenic than the wild type or complemented cut2/CUT2 strain on rice (Oryza sativa) and barley (Hordeum vulgare). It displays reduced conidiation and anomalous germling morphology, forming multiple elongated germ tubes and aberrant appressoria on inductive surfaces. We show that Cut2 mediates the formation of the penetration peg but does not play a role in spore or appressorium adhesion, or in appressorial turgor generation. Morphological and pathogenicity defects in the cut2 mutant are fully restored with exogenous application of synthetic cutin monomers, cAMP, 3-isobutyl-1-methylxanthine, and diacylglycerol (DAG). We propose that Cut2 is an upstream activator of cAMP/protein kinase A and DAG/protein kinase C signaling pathways that direct appressorium formation and infectious growth in M. grisea. Cut2 is therefore required for surface sensing leading to correct germling differentiation, penetration, and full virulence in this model fungus.