bluuebunny/crossref_metadata_2025 huggingface dataset:
An interhemispheric model of artificial ionospheric ducts
Authors: Perrine R. P. , Milikh G. M. , Papadopoulos K. , Huba J. D. , Joyce G. , Swisdak M. , Dimant Y.
Published: July 2006

A duct in Earth's ionosphere is characterized by density gradients perpendicular to the magnetic field, which enhance refractive indices and act as waveguides to whistler‐range waves. Interhemispheric ducts along magnetic field lines have implications for the transmission of ELF radio waves across the globe. Strong HF ionospheric heating has been shown to create a depletion of electrons at the heated region and could lead to a pressure perturbation that propagates along the entire magnetic field line, potentially forming an artificial duct. Here we present results from an ionospheric numerical model used to study the effects of localized HF heating on an interhemispheric magnetic flux tube. The existing Sami2 is Another Model of the Ionosphere (SAMI2) ionospheric model has been modified to include a flexible source of strong HF heating that can be varied to mimic the fluctuations in HF heating efficiencies and ionospheric conditions. Our parametric study includes varying the heating source intensity and location along the magnetic field line, revealing both linear and nonlinear relationships connecting these source parameters to maximum pressure, temperature, and density perturbations; propagation velocity of density perturbations; and characteristic heating and cooling times of the irradiated region. After a transient state, the duct structure achieves a quasi‐steady state, showing electron depletion at the heated region and density enhancements in the regions just below and above the heated region. The density perturbations propagate deep inside the plasmasphere to the conjugate F2 peak, with density enhancements along the traveling pulse boundary. The possibility of generating interhemispheric ducts is discussed.
Faulting and extension rate over the last 20,000 years in the offshore Whakatane Graben, New Zealand continental shelf
Authors: Lamarche Geoffroy , Barnes Philip M. , Bull Jonathan M.
Published: July 2006

Oblique rifting in the offshore Taupo Volcanic Zone, New Zealand, is expressed in widely distributed active normal faulting in the 20‐km‐wide Whakatane Graben. Active faults are identified along seafloor scarps and displacements of the post‐last glacial transgressive ravinement surface (<20 ka), using a network of seismic reflection data and multibeam bathymetry. The rifting involves basement blocks back‐tilted by 12–16°, controlled by large NW dipping faults with intersecting antithetic faults within the 3‐km‐thick sedimentary sequence. Faults along the graben border parallel the rift axis, while those in the center are moderately oblique to it. We present a novel method to estimate the age of a postglacial surface (7.5–20.5 ka), with consideration to spatially varying subsidence and uplift, and measure fault throw across >400 faults. We derive an extension rate at seismogenic depths (6–10 km) across the graben of 13 ± 6 mm yr−1, by summing surface measurements, assuming an average crustal fault dip of 45 ± 15°, and correcting for the discrepancies between surface and deep crustal extension estimates. Structural and kinematic data implies an extension direction 20° oblique to the rift axis, resulting in up to 4.6 ± 2.1 mm yr−1of dextral motion parallel to the rift axis. The strike‐slip motion is accommodated by dip‐slip displacements on oblique faults in the center of the graben, and oblique‐slip faulting along the rift margins. Pure dip‐slip in the graben center represents >50% of the total slip, with the Rangitaiki Fault accommodating 25% of the total extension in the graben.
Effect of suspended load on sandbar instability
Authors: Federici B. , Seminara G.
Published: July 2006

We analyze bars in sandy rivers when a significant portion of the sediment load is carried in suspension. First, we investigate the ability of a depth‐averaged formulation of both the hydrodynamics and sediment transport recently developed for slowly varying flows to capture the main mechanisms of sandbar formation. The exercise turns out to be successful and opens the way to the development of analytical and numerical models of the nonlinear development of sandbars requiring a feasible computational effort. Second, we make use of the depth‐averaged approach to analyze the nature of bar instability in sandy rivers applying Briggs criterion to distinguish between the convectively and absolutely unstable asymptotic response to an initial boundary value perturbation of bed topography. This analysis allows us to conclude that in the presence of suspended load, instability remains convective. The practical implications of such findings are discussed.
Formulation of capillary hysteresis with internal state variables
Authors: Wei Changfu , Dewoolkar Mandar M.
Published: July 2006

A thermodynamically consistent framework is proposed for modeling the hysteresis of capillarity in partially saturated porous media. Capillary hysteresis is viewed as an intrinsic dissipation mechanism, which can be characterized by a set of internal state variables. The volume fractions of pore fluids are assumed to be additively decomposed into a reversible part and an irreversible part. The irreversible part of the volumetric moisture content is introduced as one of the internal variables. It is shown that the pumping effect occurring in a porous medium experiencing a wetting/drying cycle is thermodynamically admissible. A generic evolution equation for internal variables is developed. By virtue of the notion of the bounding surface plasticity, a model of capillary hysteresis is developed, which is capable of predicting all types of (primary, secondary, and higher‐order) scanning curves within the boundary loop. Provided that the main wetting curve and the main drying curve have been experimentally determined, the proposed model requires only one additional parameter to describe all the scanning curves. The model predictions are compared with experimental measurements found in the literature, showing that the new model is capable of describing the capillary hysteretic phenomena in a variety of partially saturated porous materials.
Hydrothermal recharge and discharge guided by basement outcrops on 0.7–3.6 Ma seafloor east of the Juan de Fuca Ridge: Observations and numerical models
Authors: Hutnak M. , Fisher A. T. , Zühlsdorff L. , Spiess V. , Stauffer P. H. , Gable C. W.
Published: July 2006

The nature of ridge‐flank hydrothermal circulation guided by basement outcrops protruding through thick sediments is constrained on the eastern flank of the Juan de Fuca Ridge using combined bathymetric, seismic, and thermal observations and analytical and numerical calculations of coupled fluid‐heat flow. Observational data near the western edge of the survey area indicate that young, cool hydrothermal fluids circulate rapidly through upper basement, probably both across‐strike and along‐strike of dominant structural trends. Data from the eastern end of survey coverage (Second Ridge (SR)) indicate that upper basement is regionally nearly isothermal. A small number of basement outcrops in this area host focused hydrothermal discharge, as do additional basement outcrops to the north and south of the SR area. Numerical models of individual recharging and discharging outcrops, patterned after the Baby Bare and Grizzly Bare outcrops, suggest that local convection alone cannot explain observed patterns of seafloor heat flux near these features. Forced‐flow simulations show that reasonable rates of hydrothermal recharge and discharge, inferred from independent observations, can explain nearby seafloor heat flux, provided that upper basement permeability within and near the outcrops falls within a range of 10−13 to 10−11 m2. Free‐flow simulations of fluid circulation between paired outcrops separated by 50 km, as are Baby Bare and Grizzly Bare outcrops, are most consistent with observations when regional basement permeability is 10−11 to 10−10 m2. These simulations illustrate how sensitive these systems are to selection of appropriate properties and boundary and initial conditions.
Seasonal temperature variation below the thermocline detected by Argo floats
Authors: Hosoda Shigeki , Minato Shinya , Shikama Nobuyuki
Published: July 2006

Strong seasonal temperature variation below the thermocline is detected by Argo profiling floats. The variation is associated with a long baroclinic Rossby wave. The results of this study show that seasonal signals can be captured at 1000–2000 dbar not only in basin boundary regions or deep convection regions but also in the interior ocean. A clear, westward propagation signal is observed. The phase speed is of the same order as a theoretically derived speed. Below the thermocline, the first mode of empirical orthogonal function analysis of potential density variations in the strong signal region shows a clear seasonal variation. Even in the middle layer, the amplitude of the temperature anomaly is 0.05–0.12° C at 1200 dbar, which is equivalent to the annual standard deviation from the WOA01. These results are obtained using the dense spatial and temporal distributions provided by the Argo observations.
Effects of the transition zone above a water table on the reflection of GPR waves
Authors: Bano Maksim
Published: July 2006

We simulate two levels of water table (at 72 and 48 cm depth) by injecting water in a sand box that also contains several buried objects. GPR profiles acquired with a 1200 MHz antenna at the top of the sand box do not show any clear reflections from the water table. This is because of the existence of a ‘transition zone’ in which the velocity is a continuously decreasing function of depth. The reflection coefficient in this case decreases with increasing frequency and even vanishes for a cut‐off frequency f0 which itself increases with decreasing transition zone thickness. By modeling in the frequency domain, we explain the absence of the high‐frequency GPR reflections from the top of the saturated zone. When the wavelength is small (high frequency) compared to the thickness of the transition layer, the reflection coefficient is negligible and hence no reflections from the water table will be observed.
Electron localization function at the correlated level
Authors: Matito Eduard , Silvi Bernard , Duran Miquel , Solà Miquel
Published: July 2006

The electron localization function (ELF) has been proven so far a valuable tool to determine the location of electron pairs. Because of that, the ELF has been widely used to understand the nature of the chemical bonding and to discuss the mechanism of chemical reactions. Up to now, most applications of the ELF have been performed with monodeterminantal methods and only few attempts to calculate this function for correlated wave functions have been carried out. Here, a formulation of ELF valid for mono- and multiconfigurational wave functions is given and compared with previous recently reported approaches. The method described does not require the use of the homogeneous electron gas to define the ELF, at variance with the ELF definition given by Becke. The effect of the electron correlation in the ELF, introduced by means of configuration interaction with singles and doubles calculations, is discussed in the light of the results derived from a set of atomic and molecular systems.
Dynamic light scattering in mixed alkali metaphosphate glass forming liquids
Authors: Rodenburg B. V. , Sidebottom D. L.
Published: July 2006

We report the first ever photon correlation spectroscopy performed on single alkali and mixed alkali metaphosphate glasses at refractory temperatures above the glass transition. We find not only a significant decrease in the glass transition temperature but also a decrease in fragility for the mixed alkali composition as compared with the single akali glasses. We argue that structural relaxation in these polymeric oxide glasses is largely controlled by the cross linking cations and that the changes in fragility that we observed are a reflection of changes in the cooperativity of structural relaxation wrought by the substantial decrease in the ion mobility that accompanies the mixing of alkali ions.
Mitigation and control of the particle pinch in the Electric Tokamak
Authors: Gourdain P.-A.
Published: July 2006

The Electric Tokamak [R. J. Taylor, T. A. Carter, J.-L. Gauvreau et al., Nucl. Fusion 45, 1634 (2005)] operates at high plasma density (one and a half times the Greenwald limit) due to a strong particle pinch. However, particle accumulation causes several problems. The operation of the machine can suffer several violent disruptions that hinder the study of many plasma phenomena. Plasma motion and large density swings are undesirable because they alter continuous processes, leaving only transient regimes to study. Particle source and local temperature control can defeat the fundamental mechanisms of this ‘‘electric’’ pinch. If edge fueling feedback is not sufficient to induce quiescent behavior, the fast ion loss caused by second harmonic ion-cyclotron rf injection functions as a particle sink deep within the outer plasma cross section. By linking these strong effects to the fueling feedback, stable medium density (2×1018particles∕m3) plasmas can be sustained for several seconds. This new regime yields surprisingly long and calm discharges.
Global spectral investigation of plasma turbulence in gyrokinetic simulations
Authors: Henriksson S. V. , Janhunen S. J. , Kiviniemi T. P. , Heikkinen J. A.
Published: July 2006

Gyrokinetic global particle-in-cell simulations for a small torus with a large aspect ratio (ϵ−1>∼7) indicate a k⊥−α spectrum for electrostatic turbulence. When electrons are treated kinetically, the simulation results fit α that grows from about 1 at the plasma core to about 3 at the plasma edge for the flux surface component of the wave vector perpendicular to the magnetic field, while for adiabatic electrons α=4 is found for all radii, in agreement with the Hasegawa-Mima model. The relation between spectra and transport is investigated through the formation of an internal transport barrier. The role of flow shear in suppressing turbulence is illustrated by spectral diagnostics. A strong dependence between the presence of small wavenumbers and transport is explicitly observed. The simulated spectra are compared to recent experimental results.
Stacked white organic light-emitting devices based on a combination of fluorescent and phosphorescent emitters
Authors: Kanno Hiroshi , Giebink Noel C. , Sun Yiru , Forrest Stephen R.
Published: July 2006

We demonstrate a white stacked organic light-emitting device (WSOLED) employing the blue fluorescent emitter, 4,4′-bis(9-ethyl-3-carbazovinylene)-1,1′-biphenyl, and the green and red phosphorescent emitters, fac-tris(2-phenylpyridinato-N,C2′) iridium (III) and iridium (III) bis(2-phenyl quinolyl-N,C2′) acetylacetonate, respectively. The charge generation region consists of a Li-doped electron transport layer and a highly transparent MoOx thin film. For a two-element white SOLED (2-WSOLED), the combination of red and green phosphors with a blue fluorophore yields maximum external quantum and power efficiencies of ηext=23%±2% at a current density of J=1mA∕cm2 and ηp=14±1lm∕W at J=0.17mA∕cm2, respectively. Due to the low optical and electrical losses of the charge generation layer, the efficiencies scale approximately linearly with the number of independent emissive elements in the WSOLED. Hence, for a 3-WSOLED, the total external and power efficiencies estimated for operation of the device in a light fixture are ηext,tot=57%±6% and ηp,tot=22±2lm∕W, respectively, at a luminance of 1000cd∕m2, with Commission Internationale de L’Eclairage chromaticity coordinates of (x=0.38, y=0.44), and a color rendering index of 82. The high-efficiency, high brightness, stacked white OLED is potentially useful for solid state lighting applications.
Photonic crystal waveguide switch with a microelectromechanical actuator
Authors: Umemori Ken-ichi , Kanamori Yoshiaki , Hane Kazuhiro
Published: July 2006

A photonic crystal waveguide switch with a movable slab is proposed and fabricated by silicon micromachining. The switch structure consists of in-line input and output photonic crystal waveguide slabs and a switching slab to bridge gap between the waveguides. Driving the switching slab with a microelectromechanical actuator, the transmission between the waveguides is modulated. The switching characteristics can be explained by calculations using the finite-difference time-domain method.
Thermal stability of magnetic tunneling junctions with MgO barriers for high temperature spintronics
Authors: Liu Xiaoyong , Mazumdar Dipanjan , Shen Weifeng , Schrag B. D. , Xiao Gang
Published: July 2006

Thermal stability of MgO-based magnetic tunnel junctions has been investigated from room temperature up to 500°C, in both the memory and sensor configurations. Junctions showed magnetoresistances of over 200% at room temperature and over 100% at 300°C. Below 375°C, the resistance of the parallel state remains constant, while the antiparallel state resistance linearly decreases with temperature. Above that, a rapid increase in the resistance of both states was observed, along with an irreversible loss of magnetoresistance. Junctions in the sensor configuration exhibited a constant sensitivity of 1.0%/Oe at temperatures up to 300°C before getting degraded.
Semiconductor waveguide optical isolator based on nonreciprocal loss induced by ferromagnetic MnAs
Authors: Amemiya T. , Shimizu H. , Nakano Y. , Hai P. N. , Yokoyama M. , Tanaka M.
Published: July 2006

We fabricated TM mode InGaAlAs∕InP active waveguide optical isolators based on the magnetically induced nonreciprocal loss. We used epitaxially grown MnAs thin films as ferromagnetic electrodes of the semiconductor active waveguide optical isolators. We demonstrated TM mode nonreciprocal propagation (8.8dB∕mm) at 1540nm with an excellent ferromagnetic electrode contact, which has greater semiconductor active waveguide optical isolator performance than that of our previously reported devices with Ni∕Fe polycrystalline electrodes.
Phase transition process in oxide-ion conductor β-La2Mo2−xWxO9 assessed by internal friction method
Authors: Wang X. P. , Li D. , Fang Q. F. , Cheng Z. J. , Corbel G. , Lacorre P.
Published: July 2006

The oxygen ion diffusion and phase transition in La2Mo2−xWxO9 (x=0, 0.25, 0.75, 1.0, and 1.4) have been investigated by the internal friction method. In addition to the low-temperature relaxation peak associated with oxygen ion diffusion, an internal friction peak of phase transition type is observed around 350°C in all tungsten substituted La2Mo2O9 compounds. Based on the behavior of this peak and the ionic conduction properties, the mechanism of this peak is suggested to be associated with a transition from static disordered state to dynamic disordered state of oxygen ion distribution in anion sublattice that most probably results in a transition of the ionic conduction from the Arrhenius type to the Vogel-Tamman-Fulcher type.
Enhancement of free-carrier screening due to tunneling in coupled asymmetric GaN∕AlGaN quantum discs
Authors: Lee Kwan H. , Na Jong H. , Taylor Robert A. , Yi Sam N. , Birner Stefan , Park Young S. , Park Chang M. , Kang Tae W.
Published: July 2006

We present an investigation of free-carrier screening in coupled asymmetric GaN quantum discs with embedded AlGaN barriers using time-integrated and time-resolved microphotoluminescence measurements, supported by three-dimensional multiband k∙p computational modeling. We observe that with increasing optical excitation the carrier lifetime decreases and emission energy blueshifts. This originates from the screening of built-in piezo- and pyroelectric fields in the quantum discs by photogenerated free carriers. Due to nonresonant tunneling of carriers from the smaller disk to the larger disk, free-carrier screening is enhanced in the larger disk. Computational modeling was in good agreement with the experimental results.
Room temperature fabricated ZnO thin film transistor using high-K Bi1.5Zn1.0Nb1.5O7 gate insulator prepared by sputtering
Authors: Kim Il-Doo , Lim Mi-Hwa , Kang KyongTae , Kim Ho-Gi , Choi Si-Young
Published: July 2006

In this letter, we report on dielectric and leakage current characteristics of room temperature deposited Bi1.5Zn1.0Nb1.5O7 (BZN) films on the basis of crystallographic structure and suitability of BZN gate insulators as key building blocks in the fabrication of low voltage operating ZnO based thin-film transistors (TFTs). The BZN films exhibited a high dielectric constant (∼51) and good leakage current characteristics (∼10−7A∕cm2) at an applied voltage of 5V. All room temperature processed ZnO based TFTs using BZN gate insulator exhibited field effect mobility of 1.13cm2∕Vs and low voltage device performance less than 4V.
Space-selective laser joining of dissimilar transparent materials using femtosecond laser pulses
Authors: Watanabe Wataru , Onda Satoshi , Tamaki Takayuki , Itoh Kazuyoshi , Nishii Junji
Published: July 2006

We report on the joining of dissimilar transparent materials based on localized melting and resolidification of the materials only around the focal volume due to nonlinear absorption of focused femtosecond laser pulses. We demonstrate the joining of borosilicate glass and fused silica, whose coefficients of thermal expansion are different. The joint strength and the transmittance through joint volume were investigated by varying the translation velocity of the sample and the pulse energy of the irradiated laser pulses.
Temporally restricted substrate interactions direct fate and specification of neural precursors derived from embryonic stem cells
Authors: Goetz A. Katrin , Scheffler Bjorn , Chen Huan-Xin , Wang Shanshan , Suslov Oleg , Xiang Hui , Brüstle Oliver , Roper Steve N. , Steindler Dennis A.
Published: July 2006

It was, until now, not entirely clear how the nervous system attains its cellular phenotypic diversity and wired complexity during development. Here we describe how environmental interactions alone can modify the development of neurogenic precursor cells. Upon evaluating distinct growth-permissive substrates in an embryonic stem cell–neurogenesis assay, we found that laminin, fibronectin, and gelatin instruct neural fate and alter the functional specification of neurons when applied at distinct stages of development. Changes in phenotypic, electrophysiological, and molecular characteristics could resemble cellular events and interactions in the early embryonic brain and may explain why these extracellular matrix components transiently demarcate certain developing brain structures.
Essential role of nitric oxide in VEGF-induced, asthma-like angiogenic, inflammatory, mucus, and physiologic responses in the lung
Authors: Bhandari Vineet , Choo-Wing Rayman , Chapoval Svetlana P. , Lee Chun G. , Tang C. , Kim Y. K. , Ma Bing , Baluk Peter , Lin Michelle I. , McDonald Donald M. , Homer Robert J. , Sessa William C. , Elias Jack A.
Published: July 2006

VEGF, nitric oxide (NO), inflammation, and vascular- and extravascular remodeling coexist in asthma and other disorders. In these responses, VEGF regulates angiogenesis. VEGF also induces inflammation and remodeling. The mechanisms of the latter responses have not been defined, however. We hypothesized that VEGF-induces extravascular tissue responses via NO-dependent mechanisms. To evaluate this hypothesis, we compared the effects of transgenic VEGF165in lungs from normal mice, mice treated with pan-NO synthase (NOS) or endothelial NOS (eNOS) inhibitors, and mice with null mutations of inducible NOS (iNOS) or eNOS. These studies demonstrate that VEGF selectively stimulates eNOS and iNOS. They also demonstrate that VEGF induces pulmonary alterations via NO-dependent and -independent mechanisms with angiogenesis, edema, mucus metaplasia, airway hyperresponsiveness, lymphocyte accumulation, dendritic cell hyperplasia andS-nitrosoglutathione reductase stimulation being NO-dependent and dendritic cell activation being NO-independent. Furthermore, they demonstrate that eNOS and iNOS both contribute to these responses. NO/NOS-based interventions may be therapeutic in VEGF-driven inflammation and remodeling.
Ebp1 isoforms distinctively regulate cell survival and differentiation
Authors: Liu Zhixue , Ahn Jee-Yin , Liu Xia , Ye Keqiang
Published: July 2006

Ebp1, an ErbB3 receptor-binding protein, inhibits the proliferation and induces the differentiation of human cancer cells. Ebp1 binds nuclear Akt and prevents DNA fragmentation by inhibiting caspase-activated DNase. Here, we show that Ebp1 possesses two different isoforms, p48 and p42, which differentially mediate PC12 cell survival and differentiation. The longer-form p48 localizes in both the cytoplasm and the nucleus and suppresses apoptosis, whereas the shorter-form p42 predominantly resides in the cytoplasm and promotes cell differentiation. EGF strongly stimulates p42 to bind ErbB3, and the association depends on PKC-mediated phosphorylation of Ebp1. By contrast, p48 does not bind to ErbB3 regardless of EGF treatment. Overexpression of p48 provokes cell proliferation, which is inhibited by p42. Moreover, nerve growth factor elicits extensive sprouting in p42 stably transfected PC12 cells, whereas p48 cells reveal modest neurite outgrowth. Although mitogen-activated protein kinase cascade remains similar in both cells, Akt is more active in p48 cells than in p42 cells. Thus, Ebp1 might regulate cell survival and differentiation through two distinctive p48 and p42 isoforms.
Details of Toll-like receptor:adapter interaction revealed by germ-line mutagenesis
Authors: Jiang Zhengfan , Georgel Philippe , Li Chenglong , Choe Jungwoo , Crozat Karine , Rutschmann Sophie , Du Xin , Bigby Tim , Mudd Suzanne , Sovath Sosathya , Wilson Ian A. , Olson Arthur , Beutler Bruce
Published: July 2006

The immunovariant
N
-ethyl-
N
-nitrosourea-induced mutations Pococurante (Poc) and Lackadaisical were found to alter MyD88, creating striking receptor-selective effects. Poc, in particular, prevented sensing of all MyD88-dependent Toll-like receptor (TLR) ligands except diacyl lipopeptides. Furthermore, Poc-site and classical BB loop mutations caused equivalent phenotypes when engrafted into any TLR/IL-1 receptor/resistance (TIR) domain. These observations, complemented by data from docking studies and site-directed mutagenesis, revealed that BB loops and Poc sites interact homotypically across the receptor:adapter signaling interface, whereas the C-terminal α
E
-helices support adapter:adapter and receptor:receptor oligomerization. We have thus defined the TIR domain surface that mediates association between TLRs and MyD88 and the surface required for MyD88 or TLR oligomerization. Moreover, MyD88 engages individual TLRs differently, suggesting the feasibility of selective pharmacologic TIR domain receptor blockade.
Yellow flowers generated by expression of the aurone biosynthetic pathway
Authors: Ono Eiichiro , Fukuchi-Mizutani Masako , Nakamura Noriko , Fukui Yuko , Yonekura-Sakakibara Keiko , Yamaguchi Masaatsu , Nakayama Toru , Tanaka Takaharu , Kusumi Takaaki , Tanaka Yoshikazu
Published: July 2006

Flower color is most often conferred by colored flavonoid pigments. Aurone flavonoids confer a bright yellow color on flowers such as snapdragon (
Antirrhinum majus
) and dahlia (
Dahlia variabilis
).
A. majus
aureusidin synthase (AmAS1) was identified as the key enzyme that catalyzes aurone biosynthesis from chalcones, but transgenic flowers overexpressing
AmAS1
gene failed to produce aurones. Here, we report that chalcone 4′-
O
-glucosyltransferase (4′CGT) is essential for aurone biosynthesis and yellow coloration
in vivo
. Coexpression of the
Am4
′
CGT
and
AmAS1
genes was sufficient for the accumulation of aureusidin 6-
O
-glucoside in transgenic flowers (
Torenia hybrida
). Furthermore, their coexpression combined with down-regulation of anthocyanin biosynthesis by RNA interference (RNAi) resulted in yellow flowers. An Am4′CGT-GFP chimeric protein localized in the cytoplasm, whereas the AmAS1(N1-60)-RFP chimeric protein was localized to the vacuole. We therefore conclude that chalcones are 4′-
O
-glucosylated in the cytoplasm, their 4′-
O
-glucosides transported to the vacuole, and therein enzymatically converted to aurone 6-
O
-glucosides. This metabolic pathway is unique among the known examples of flavonoid, including anthocyanin biosynthesis because, for all other compounds, the carbon backbone is completed before transport to the vacuole. Our findings herein not only demonstrate the biochemical basis of aurone biosynthesis but also open the way to engineering yellow flowers for major ornamental species lacking this color variant.
A network of protein interactions determines polyglutamine toxicity
Authors: Duennwald Martin L. , Jagadish Smitha , Giorgini Flaviano , Muchowski Paul J. , Lindquist Susan
Published: July 2006

Several neurodegenerative diseases are associated with the toxicity of misfolded proteins. This toxicity must arise from a combination of the amino acid sequences of the misfolded proteins and their interactions with other factors in their environment. A particularly compelling example of how profoundly these intramolecular and intermolecular factors can modulate the toxicity of a misfolded protein is provided by the polyglutamine (polyQ) diseases. All of these disorders are caused by glutamine expansions in proteins that are broadly expressed, yet the nature of the proteins that harbor the glutamine expansions and the particular pathologies they produce are very different. We find, using a yeast model, that amino acid sequences that modulate polyQ toxicity in cis can also do so in trans. Furthermore, the prion conformation of the yeast protein Rnq1 and the level of expression of a suite of other glutamine-rich proteins profoundly affect polyQ toxicity. They can convert polyQ expansion proteins from toxic to benign and vice versa. Our work presents a paradigm for how a complex, dynamic interplay between intramolecular features of polyQ proteins and intermolecular factors in the cellular environment might determine the unique pathobiologies of polyQ expansion proteins.
Mutant
LYS2
mRNAs retained and degraded in the nucleus of
Saccharomyces cerevisiae
Authors: Das Biswadip , Das Satarupa , Sherman Fred
Published: July 2006

We previously demonstrated that mRNAs retained in the nucleus of
Saccharomyces cerevisiae
are subjected to a degradation system-designated DRN (degradation of mRNA in the nucleus), that is diminished in
cbc1
-Δ or
cbc2
-Δ mutants lacking components of the cap-binding complex and in
rrp6
-Δ mutants lacking Rrp6p, a 3′ to 5′ nuclear exonuclease. Two mutants,
lys2-187
and
lys2-121
, were uncovered by screening numerous
lys2
mutants for suppression by
cbc1
-Δ and
rrp6
-Δ. Both mutants were identical and contained the two base changes, one of which formed a TGA nonsense codon.
LYS2
mRNAs from the
lys2-187
and related mutants were rapidly degraded, and the degradation was suppressed by
cbc1
-Δ and
rrp6
-Δ. The U1A-GFP imaging procedure was used to show that the
lys2-187
mRNA was partially retained in the nucleus, explaining the susceptibility to DRN. The creation of several derivatives of
lys2-187
by site-directed mutagenesis revealed that the in-frame TGA by itself was not responsible for the increased susceptibility to DRN. Thus, mRNAs susceptible to DRN can be formed by a 2-bp change. Furthermore, this “retention signal” causing susceptibility to DRN is lost by altering one of the base pairs, establishing that mRNAs susceptible and unsusceptible to DRN can be attributed to a single nucleotide in the proper context.
Prehistoric agricultural depletion of soil nutrients in Hawai'i
Authors: Hartshorn A. S. , Chadwick O. A. , Vitousek P. M. , Kirch P. V.
Published: July 2006

We investigated the fate of soil nutrients after centuries of
indigenous dryland agriculture in Hawai‘i using a coupled
geochemical and archaeological approach. Beginning ≈500 years
ago, farmers began growing dryland taro and sweet potato on the
leeward slopes of East Maui. Their digging sticks pierced a subsurface
layer of cinders, enhancing crop access to the soil water stored below
the intact cinders. Cultivation also catalyzed nutrient losses,
directly by facilitating leaching of mobile nutrients after disturbing
a stratigraphic barrier to vertical water movement, and indirectly by
increasing mineral weathering and subsequent uptake and harvest. As a
result, centuries of cultivation lowered volumetric total calcium,
magnesium, sodium, potassium, and phosphorus content by 49%,
28%, 75%, 37%, and 32%, respectively. In
the absence of written records, we used the difference in soil
phosphorus to estimate that prehistoric yields were sufficient to meet
local demand over very long time frames, but the associated
acceleration of nutrient losses could have compromised subsequent
yields.
New consensus nomenclature for mammalian keratins
Authors: Schweizer Jürgen , Bowden Paul E. , Coulombe Pierre A. , Langbein Lutz , Lane E. Birgitte , Magin Thomas M. , Maltais Lois , Omary M. Bishr , Parry David A.D. , Rogers Michael A. , Wright Mathew W.
Published: July 2006

Keratins are intermediate filament–forming proteins that provide mechanical support and fulfill a variety of additional functions in epithelial cells. In 1982, a nomenclature was devised to name the keratin proteins that were known at that point. The systematic sequencing of the human genome in recent years uncovered the existence of several novel keratin genes and their encoded proteins. Their naming could not be adequately handled in the context of the original system. We propose a new consensus nomenclature for keratin genes and proteins that relies upon and extends the 1982 system and adheres to the guidelines issued by the Human and Mouse Genome Nomenclature Committees. This revised nomenclature accommodates functional genes and pseudogenes, and although designed specifically for the full complement of human keratins, it offers the flexibility needed to incorporate additional keratins from other mammalian species.
Actin depolymerization is sufficient to induce programmed cell death in self-incompatible pollen
Authors: Thomas Steven G. , Huang Shanjin , Li Shutian , Staiger Christopher J. , Franklin-Tong Vernonica E.
Published: July 2006

Self-incompatibility (SI) prevents inbreeding through specific recognition and rejection of incompatible pollen. In incompatible Papaver rhoeas pollen, SI triggers a Ca2+ signaling cascade, resulting in the inhibition of tip growth, actin depolymerization, and programmed cell death (PCD). We investigated whether actin dynamics were implicated in regulating PCD. Using the actin-stabilizing and depolymerizing drugs jasplakinolide (Jasp) and latrunculin B, we demonstrate that changes in actin filament levels or dynamics play a functional role in initiating PCD in P. rhoeas pollen, triggering a caspase-3–like activity. Significantly, SI-induced PCD in incompatible pollen was alleviated by pretreatment with Jasp. This represents the first account of a specific causal link between actin polymerization status and initiation of PCD in a plant cell and significantly advances our understanding of the mechanisms involved in SI.
Signaling-dependent immobilization of acylated proteins in the inner monolayer of the plasma membrane
Authors: Corbett-Nelson Elaine F. , Mason David , Marshall John G. , Collette Yves , Grinstein Sergio
Published: July 2006

Phospholipids play a critical role in the recruitment and activation of several adaptors and effectors during phagocytosis. Changes in lipid metabolism during phagocytosis are restricted to the phagocytic cup, the area of the plasmalemma lining the target particle. It is unclear how specific lipids and lipid-associated molecules are prevented from diffusing away from the cup during the course of phagocytosis, a process that often requires several minutes. We studied the mobility of lipid-associated proteins at the phagocytic cup by measuring fluorescence recovery after photobleaching. Lipid-anchored (diacylated) fluorescent proteins were freely mobile in the unstimulated membrane, but their mobility was severely restricted at sites of phagocytosis. Only probes anchored to the inner monolayer displayed reduced mobility, whereas those attached to the outer monolayer were unaffected. The immobilization persisted after depletion of plasmalemmal cholesterol, ruling out a role of conventional “rafts.” Corralling of the probes by the actin cytoskeleton was similarly discounted. Instead, the change in mobility required activation of tyrosine kinases. We suggest that signaling-dependent recruitment of adaptors and effectors with lipid binding domains generates an annulus of lipids with restricted mobility.
Twist mediates suppression of inflammation by type I IFNs and Axl
Authors: Sharif M. Nusrat , Šošić Dražen , Rothlin Carla V. , Kelly Erin , Lemke Greg , Olson Eric N. , Ivashkiv Lionel B.
Published: July 2006

Type I interferons (IFNs) are pleiotropic cytokines with antiviral and immunomodulatory properties. The immunosuppressive actions of type I IFNs are poorly understood, but IFN-mediated suppression of TNFα production has been implicated in the regulation of inflammation and contributes to the effectiveness of type I IFNs in the treatment of certain autoimmune and inflammatory diseases. In this study, we investigated mechanisms by which type I IFNs suppress induction of TNFα production by immune complexes, Fc receptors, and Toll-like receptors. Suppression of TNFα production was mediated by induction and activation of the Axl receptor tyrosine kinase and downstream induction of Twist transcriptional repressors that bind to E box elements in the TNF promoter and suppress NF-κB–dependent transcription. Twist expression was activated by the Axl ligand Gas6 and by protein S and apoptotic cells. These results implicate Twist proteins in regulation of TNFα production by antiinflammatory factors and pathways, and provide a mechanism by which type I IFNs and Axl receptors suppress inflammatory cytokine production.
How Business Enterprises Use Technology: Extending the Demand-Side Turn
Authors: Yates Joanne
Published: July 2006

Today, we are all aware of the importance of technology to modern business, including process technologies as well as consumer and industrial products incorporating technology. The significant role of technology in business (and vice versa) is not, of course, new. Although the history of technology and business history have different professional organizations and often focus on different theoretical and empirical phenomena, the large number of historians who work at the intersection of the two today reflects the importance of each to the other over a much longer time period. Yet historians of both types still too often give short shrift to the role of business enterprises as technology users as well as to the actual business use of technology.
Address of Louise Arbour, UN High Commissioner for Human Rights
Authors:   In Our Name and On Our Behalf
Published: July 2006

In July 2001, a few years after my first encounter with the intersection of criminal law and international law at the International Criminal Tribunals for the Former Yugoslavia (ICTY) and for Rwanda (ICTR), I asked the following question at a lecture at Melbourne University:

While the political will to pursue war criminals was first lacking, is there, as some seem to fear, a danger that it will become relentless? If so, what effect will that have on the integrity of the complex aspirations and methodologies of criminal law as an instrument of social control in a democracy?

After 11 September of the same year, the question acquired added acuity as I assumed that it would be not just war criminals but also international terrorists that the criminal law framework, domestic and international, would now be pursuing. I obviously was gravely mistaken in my concerns. The pursuit of terrorist suspects seems to have little to do with criminal or international law as we know it. Hence the real questions: What is it then about? Under what legal framework, if any, does it purport to operate and who is accountable to whom?
‘Caveat Investor’? The Relevance of the Conduct of the Investor Under the Fair and Equitable Treatment Standard
Authors: Muchlinski Peter
Published: July 2006

The role that investor conduct plays in applying the fair and equitable treatment standard is relatively unexplored. On the basis of conceptual analysis, and emerging international judicial and arbitral case law, this article suggests that investor conduct is an important consideration. Investor duties are being accepted in relation to the avoidance of unconscionable conduct, the reasonable assessment of investment risk in the host country, and a duty to operate an investment reasonably. These requirements may be said to lead to a new limit upon the fair and equitable treatment standard encapsulated in the phrase ‘Caveat Investor’.
The Concept Of Employment Contract In European Union Private Law
Authors: Cavalier Georges , Upex Robert
Published: July 2006

This article provides a thorough analysis of the employment contract in comparative European private law and Community law. It argues that a common concept of employment contract should prevail in European private law. In that respect, the autonomous and broad interpretation which has been given to the term ‘worker’ in Community law could be a basis for adoption of an autonomous concept of the employment contract in European private law.
II. The Ankara Agreement, Turkey, and the Eu
Authors: Katselli Elena
Published: July 2006

The Republic of Cyprus became independent on 16 August 1960 with the conclusion of three agreements between Cyprus, Greece, Turkey and the United Kingdom: the Treaty of Establishment,1the Treaty of Guarantee,2and the Treaty of Alliance.3Due to limited space, this article will not consider the troubled history of the new Republic the structures of which were literally shattered by an unworkable and dysfunctional Constitution a few years only after its establishment and which eventually led to the Turkish invasion and continuing occupation of one third of its territory.4Rather, this article intends to focus on recent legal developments provoked by Turkey's refusal to recognize the Republic of Cyprus, a Member State of the United Nations and as from May 2004 a Member of the European Union, in the context of Turkey's own aspirations to become an EU Member State.
Tick prevalence and species diversity on Aldabran giant tortoises (Dipsochelys dussumieri) in relation to host range and host size in a restored ecosystem, Kenya
Authors: Okanga Sharon , Rebelo Camille
Published: July 2006

Tick species density and diversity on Aldabran tortoises was investigated in relation to the habitat range and size of each tortoise. Identification of tick infestation patterns forms an important aspect of effective tick control. Ten Aldabran tortoises were de‐ticked and monitored over the course of 2 months. Tick species found were Amblyomma sparsum, Amblyomma nuttalli, Amblyomma hebraeum and Boophilus decoloratus, with the most prevalent species found being A. sparsum. Tick loads varied considerably from 20 to 214 ticks per tortoise, with most ticks collected from the head/neck region. Tortoises ranging outside Haller Park had higher tick loads (70–214) compared with tortoises ranging within Haller Park (20–99). Tick load was not correlated with tortoise size. Results indicate that tick loads are related to the habitat range of the tortoises and may indirectly also be related to food preference and host food availability. Implications of the findings and appropriate tick control measures are discussed.
Cell cycle genes regulate vestigial and scalloped to ensure normal proliferation in the wing disc of Drosophila melanogaster
Authors: Legent Kevin , Dutriaux Annie , Delanoue Rénald , Silber Joël
Published: July 2006

In Drosophila, the Vestigial‐Scalloped (VG–SD) dimeric transcription factor is required for wing cell identity and proliferation. Previous results have shown that VG–SD controls expression of the cell cycle positive regulator dE2F1 during wing development. Since wing disc growth is a homeostatic process, we investigated the possibility that genes involved in cell cycle progression regulate vg and sd expression in feedback loops. We focused our experiments on two major regulators of cell cycle progression: dE2F1 and the antagonist dacapo (dap). Our results reinforce the idea that VG/SD stoichiometry is critical for correct development and that an excess in SD over VG disrupts wing growth. We reveal that transcriptional activity of VG–SD and the VG/SD ratio are both modulated by down‐expression of cell cycle genes. We also detected a dap‐induced sd up‐regulation that disrupts wing growth. Moreover, we observed a rescue of a vg hypomorphic mutant phenotype by dE2F1 that is concomitant with vg and sd induction. This regulation of the VG–SD activity by dE2F1 is dependent on the vg genetic background. Our results support the hypothesis that cell cycle genes fine‐tune wing growth and cell proliferation, in part, through control of the VG/SD stoichiometry and activity. This points to a homeostatic feedback regulation between proliferation regulators and the VG–SD wing selector.
Asylum nursing as a career in the United Kingdom, 1890–1910
Authors: Brimblecombe Neil
Published: July 2006

Background. Nursing staff in lunatic asylums provided the day‐to‐day care and containment of patients and were the direct occupational ancestors of today's mental health nurses.

Aim. This study explores (1) How was asylum nursing seen by asylum nurses themselves and by others, particularly other healthcare workers? (2) What were the demographic characteristics of those who became asylum nurses and what were their patterns of employment?

Methods. Information regarding contemporary views of asylum nursing were gathered through searching a range of contemporary journals and other publications. Statistical information regarding patterns of employment was gathered from asylum records and census data.

Findings. During the period from 1890 to 1910 the image of asylum nursing was poor. Allegations of brutality continued to effect its image, despite claims by asylum nurses and medical superintendents that such generalizations were unfair and that asylum nursing was at least as valuable as any other from of nursing. The middle class leadership of voluntary hospital general nursing was particularly critical. At the Three Counties Asylum in Southern England, the majority of asylum nurses came from unskilled or semi‐skilled backgrounds. 43% were recruited locally; 43% of nursing staff left after less than a year, and less than a quarter remained after 3 years. Even those individuals thought to be suitable by prior experience, such as ex‐servicemen, often did not stay long. Dismissals were common, especially amongst male staff (22%). The discipline was hard, hours long and the work often unpleasant.

Conclusions. For asylum nurses conditions were poor, the work difficult and their public image negative. The reality was that people from working class backgrounds entered asylum nursing at a relatively young age, often travelling some distance to do so, and then many only stayed for short periods. However, some women were able to take advantage of the possibilities offered by asylum work to develop a career for themselves in the absence of other opportunities.