bluuebunny/crossref_metadata_2025 huggingface dataset:
High peak luminance of molecularly dye-doped organic light-emitting diodes under intense voltage pulses
Authors: Wei B. , Ichikawa M. , Furukawa K. , Koyama T. , Taniguchi Y.
Published: August 2005

The performance and efficiency of molecularly doped organic light-emitting devices (OLEDs) using voltage pulses have been investigated. The maximum current density and peak luminance have been found to depend on the pulse duration and device size, which was attributed to the heat effect in device. The self-quenching of dye molecules, especially at a high current density of ∼A∕cm2, can be effectively inhibited using a low concentration of acceptor in donor system as a light-emitting layer (EML). For an OLED using a 0.4-mol% rubrene in Alq3 as an EML, a maximum peak luminance of 5.66×106cd∕m2 at 52.8V can be sustained under the voltage pulses of duration of 5μs. The current efficiency has been observed to decrease rapidly with the current density in device, which was believed to result from the annihilation of excitons. We have also investigated the performance of a pulsed OLED with an emitter layer of 4.0-mol% 1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene in 4,4′-bis(9-carbazolyl)biphenyl, which has been known to exhibit low-amplified spontaneous emission under a pulsed nitrogen laser.
Optical and magneto-optical properties and magnetorefractive effect in metal-insulator CoFe–Al2O3 granular films
Authors: Kravets V. G. , Poperenko L. V. , Yurgelevych I. V. , Pogorily A. M. , Kravets A. F.
Published: August 2005

Optical and magneto-optical properties of metal-insulator (CoFe)x(Al2O3)1−x granular films have been investigated. The results have been compared with the experimental data of the magnetorefractive effect in the IR region. The optical and magneto-optical spectra of the films depend strongly on the volume fraction of ferromagnetic particles. It was found that the Kerr effect is substantially increased in the spectral region of the plasma frequency. It was revealed that appearance peculiarities observed in the magnetoreflection spectra at 7.5–9.5μm are associated with the excitation of longitudinal phonon modes in the Al2O3 dielectric matrix. It has been shown that both intraband and interband electron transitions contribute to the magnetoresistivity as well as to the IR magnetoreflection. The optical and magneto-optical properties of the (CoFe)x(Al2O3)1−x granular films can be interpreted in the frame of the effective-medium approximation. The magnetorefractive effect can be explained in terms of the modified Hagen-Rubens relation.
Electron acceleration in combined intense laser fields and self-consistent quasistatic fields in plasma
Authors: Qiao Bin , He X. T. , Zhu Shao-ping , Zheng C. Y.
Published: August 2005

The acceleration of plasma electron in intense laser-plasma interaction is investigated analytically and numerically, where the conjunct effect of laser fields and self-consistent spontaneous fields (including quasistatic electric field Esl, azimuthal quasistatic magnetic field Bsθ and the axial one Bsz) is completely considered for the first time. An analytical relativistic electron fluid model using test-particle method has been developed to give an explicit analysis about the effects of each quasistatic fields. The ponderomotive accelerating and scattering effects on electrons are partly offset by Esl, furthermore, Bsθ pinches and Bsz collimates electrons along the laser axis. The dependences of energy gain and scattering angle of electron on its initial radial position, plasma density, and laser intensity are, respectively, studied. The qualities of the relativistic electron beam (REB), such as energy spread, beam divergence, and emitting (scattering) angle, generated by both circularly polarized (CP) and linearly polarized (LP) lasers are studied. Results show CP laser is of clear advantage comparing to LP laser for it can generate a better REB in collimation and stabilization.
The effect of artificial diffusivity on the flute instability
Authors: Ryutov D. D. , Cohen B. I , Cohen R. H. , Hooper E. B. , Sovinec C. R.
Published: August 2005

Sometimes, in order to improve the performance of magnetohydrodynamical codes, artificial diffusivity (D) is introduced in the mass continuity equation. In this communication, an analysis of the effect of the artificial diffusivity on the low-β plasma stability in a simple geometry is presented. It is shown that, at low diffusivity, one recovers classical results, whereas at high diffusivity the plasma becomes more unstable. Dependence of the stability on D is suppressed if the volume of the flux tube varies insignificantly in the course of the perturbation growth. These observations may help the code developers and users to identify the regimes where the artificial diffusivity is not affecting the results (or vice versa).
Collisional scattering for binary Coulomb interactions that are cut off at a distance different than the Debye length
Authors: Correa J. R. , Chang Yongbin , Ordonez C. A.
Published: August 2005

Collisional scattering is considered within a system of charged particles experiencing binary Coulomb interactions when the scale length for the range of each interaction is not isotropic and is not necessarily equal to the Debye length. For example, one or more dimensions of the system could be smaller than the Debye length. The effect is assessed by evaluating integrals over the impact cross section. Cutoffs on both the impact parameter and the Coulomb interaction potential are employed, and no assumption is made regarding the value of the Coulomb logarithm. Two expressions are found that have a dependence on the cutoff lengths, with one of the expressions being associated with the Coulomb logarithm. Collisional scattering within an electrostatic ion trap is considered by way of example.
Direct evidence of electromigration failure mechanism in dual-damascene Cu interconnect tree structures
Authors: Vairagar A. V. , Mhaisalkar S. G. , Meyer M. A. , Zschech E. , Krishnamoorthy Ahila , Tu K. N. , Gusak A. M.
Published: August 2005

In situ secondary electron microscope (SEM) characterizations were carried out to study electromigration failure mechanism in dual-damascene Cu interconnect tree structures, which are important for reliability assessment as well as design optimizations of on-chip interconnects. Direct evidence of electromigration-induced degradation in interconnect tree structure consisting of void nucleation and void movement in opposite direction to electron flow along the Cu∕SiNx interface was unraveled. The peculiar electromigration behavior of Cu interconnect tree structures can be clearly understood based on this mechanism. Dependence of electromigration mechanism of a segment in a Cu interconnect tree on current configuration in neighboring interconnect segment is discussed in detail.
Core-shell SiGe whiskers with composition gradient along the axial direction: Cross-sectional analysis
Authors: Mori Kenichi , Shoda Kaoru , Kohno Hideo
Published: August 2005

Core-shell SiGe whiskers were grown via a fully self-organized process without artificial control of source materials. Whiskers were several hundred nanometers in diameter at the top and became thicker towards the bottom, and 100μm long. Cross-sectional observations of a whisker clearly showed that the whisker had core-shell structure: both the core and the shell were SiGe and the core was Ge-richer in comparison to the shell. It was also elucidated that the whisker had composition gradient along the axial direction. It was concluded that core and the shell were formed via vapor-liquid-solid and vapor-solid processes, respectively.
Photoluminescence characterization of midinfrared InNxAs1−x/In0.53Ga0.47As∕InP multiquantum wells with various N contents
Authors: Sun H. D. , Clark A. H. , Calvez S. , Dawson M. D. , Shih D. K. , Lin H. H.
Published: August 2005

We report the temperature-dependent photoluminescence characterization of InNxAs1−x∕In0.53Ga0.47As∕InP multiple quantum wells with various N contents emitting in the midinfrared wavelength range. The emission wavelength in this material system can be tuned by the N content, but the bowing effect is much weaker than in GaNAs. The correlation between the optical properties and the interface quality is demonstrated by examining the barrier-related emission. The role played by N is elucidated by comparing quantum well samples having either zero, low (0.25%) or high (5%) N content.
Neural mechanism in anterior prefrontal cortex for inhibition of prolonged set interference
Authors: Konishi Seiki , Chikazoe Junichi , Jimura Koji , Asari Tomoki , Miyashita Yasushi
Published: August 2005

Once one cognitive set dominates our behavior, it continues to influence subsequent behavior for a while even after a task to be performed is changed to another. Despite abundant knowledge of the inhibitory mechanisms that are recruited at the first trial after the change (the first inhibition trial), little is known about the inhibition of prolonged proactive interference from a previous set that lingers for several trials after the first inhibition trial. The present functional MRI study explored the neural mechanisms for inhibition of a previous set that were recruited after the first inhibition trial. A modified Wisconsin Card Sorting Test was used where “dual-match stimuli” were intermittently presented and allowed subjects to perform correctly based on previously appropriate, now inappropriate, responses. In response to the dual-match stimulus at “release” trials presented after the first inhibition trials, the subjects were transiently exempted from inhibiting the prolonged previous set. As expected from the exempted inhibitory demands, significant reaction time decrease was revealed in the release trials. Consistent with the behavioral results, transient signal decrease time-locked to the release trials was revealed in the left anterior part of the superior frontal sulcus. Moreover, the anterior prefrontal region was not sensitive to the task change, which exhibited a marked contrast to the left posterior inferior prefrontal region that showed significant signal changes in both events. These results revealed multiple inhibitory mechanisms in the lateral prefrontal cortex that are recruited in different temporal contexts of the interference from a previous cognitive set.
Structure of a bacterial BLUF photoreceptor: Insights into blue light-mediated signal transduction
Authors: Jung Astrid , Domratcheva Tatiana , Tarutina Marina , Wu Qiong , Ko Wen-huang , Shoeman Robert L. , Gomelsky Mark , Gardner Kevin H. , Schlichting Ilme
Published: August 2005

Light is an essential environmental factor, and many species have evolved the capability to respond to it. Blue light is perceived through three flavin-containing photoreceptor families: cryptochromes, light-oxygen-voltage, and BLUF (sensor of blue light using flavin adenine dinucleotide, FAD) domain proteins. BLUF domains are present in various proteins from Bacteria and lower Eukarya. They are fully modular and can relay signals to structurally and functionally diverse output units, most of which are implicated in nucleotide metabolism. We present the high resolution crystal structure of the dark resting state of BlrB, a short BLUF domain-containing protein from
Rhodobacter sphaeroides
. The structure reveals a previously uncharacterized FAD-binding fold. Along with other lines of evidence, it suggests mechanistic aspects for the photocycle that is characterized by a red-shifted absorbance of the flavin. The isoalloxazine ring of FAD binds in a cleft between two helices, whereas the adenine ring points into the solvent. We propose that the adenine ring serves as a hook mediating the interaction with its effector/output domain. The structure suggests a unique photochemical signaling switch in which the absorption of light induces a structural change in the rim surrounding the hook, thereby changing the protein interface between BLUF and the output domain.
Conformable, flexible, large-area networks of pressure and thermal sensors with organic transistor active matrixes
Authors: Someya Takao , Kato Yusaku , Sekitani Tsuyoshi , Iba Shingo , Noguchi Yoshiaki , Murase Yousuke , Kawaguchi Hiroshi , Sakurai Takayasu
Published: August 2005

Skin-like sensitivity, or the capability to recognize tactile information, will be an essential feature of future generations of robots, enabling them to operate in unstructured environments. Recently developed large-area pressure sensors made with organic transistors have been proposed for electronic artificial skin (E-skin) applications. These sensors are bendable down to a 2-mm radius, a size that is sufficiently small for the fabrication of human-sized robot fingers. Natural human skin, however, is far more complex than the transistor-based imitations demonstrated so far. It performs other functions, including thermal sensing. Furthermore, without conformability, the application of E-skin on three-dimensional surfaces is impossible. In this work, we have successfully developed conformable, flexible, large-area networks of thermal and pressure sensors based on an organic semiconductor. A plastic film with organic transistor-based electronic circuits is processed to form a net-shaped structure, which allows the E-skin films to be extended by 25%. The net-shaped pressure sensor matrix was attached to the surface of an egg, and pressure images were successfully obtained in this configuration. Then, a similar network of thermal sensors was developed with organic semiconductors. Next, the possible implementation of both pressure and thermal sensors on the surfaces is presented, and, by means of laminated sensor networks, the distributions of pressure and temperature are simultaneously obtained.
Distinct basal ganglia territories are engaged in early and advanced motor sequence learning
Authors: Lehéricy Stéphane , Benali Habib , Van de Moortele Pierre-François , Pélégrini-Issac Mélanie , Waechter Tobias , Ugurbil Kamil , Doyon Julien
Published: August 2005

In this study, we used functional MRI (fMRI) at high field (3T) to track the time course of activation in the entire basal ganglia circuitry, as well as other motor-related structures, during the explicit learning of a sequence of finger movements over a month of training. Fourteen right-handed healthy volunteers had to practice 15 min daily a sequence of eight moves using the left hand. MRI sessions were performed on days 1, 14 and 28. In both putamen, activation decreased with practice in rostrodorsal (associative) regions. In contrast, there was a significant signal increase in more caudoventral (sensorimotor) regions of the putamen. Subsequent correlation analyses between signal variations and behavioral variables showed that the error rate (movement accuracy) was positively correlated with signal changes in areas activated during early learning, whereas reaction time (movement speed) was negatively correlated with signal changes in areas activated during advanced learning stages, including the sensorimotor putamen and globus pallidus. These results suggest the possibility that motor representations shift from the associative to the sensorimotor territories of the striato-pallidal complex during the explicit learning of motor sequences, suggesting that motor skills are stored in the sensorimotor territory of the basal ganglia that supports a speedy performance.
Real-time imaging of type III secretion:
Salmonella
SipA injection into host cells
Authors: Schlumberger Markus C. , Müller Andreas J. , Ehrbar Kristin , Winnen Brit , Duss Iwan , Stecher Bärbel , Hardt Wolf-Dietrich
Published: August 2005

Many pathogenic and symbiotic Gram-negative bacteria employ type III secretion systems to inject “effector” proteins into eukaryotic host cells. These effectors manipulate signaling pathways to initiate symbiosis or disease. By using time-lapse microscopy, we have imaged delivery of the
Salmonella
type III effector protein SipA/SspA into animal cells in real time. SipA delivery mostly began 10-90 sec after docking and proceeded for 100-600 sec until the bacterial SipA pool (6 ± 3 × 10
3
molecules) was exhausted. Similar observations were made for the effector protein SopE. This visualization of type III secretion in real time explains the efficiency of host cell manipulation by means of this virulence system.
Generation of phytate-free seeds in
Arabidopsis
through disruption of inositol polyphosphate kinases
Authors: Stevenson-Paulik Jill , Bastidas Robert J. , Chiou Shean-Tai , Frye Roy A. , York John D.
Published: August 2005

Phytate (inositol hexakisphosphate, IP
6
) is a regulator of intracellular signaling, a highly abundant animal antinutrient, and a phosphate store in plant seeds. Here, we report a requirement for inositol polyphosphate kinases,
AtIPK1
and
AtIPK2
β, for the later steps of phytate synthesis in
Arabidopsis thaliana
. Coincident disruption of these kinases nearly ablates seed phytate without accumulation of phytate precursors, increases seed-free phosphate by 10-fold, and has normal seed yield. Additionally, we find a requirement for inositol tetrakisphosphate (IP
4
)/inositol pentakisphosphate (IP
5
) 2-kinase activity in phosphate sensing and root hair elongation. Our results define a commercially viable strategy for the genetic engineering of phytate-free grain and provide insights into the role of inositol polyphosphate kinases in phosphate signaling biology.
A Role for Fis1 in Both Mitochondrial and Peroxisomal Fission in Mammalian Cells
Authors: Koch Annett , Yoon Yisang , Bonekamp Nina A. , McNiven Mark A. , Schrader Michael
Published: August 2005

The mammalian dynamin-like protein DLP1/Drp1 has been shown to mediate both mitochondrial and peroxisomal fission. In this study, we have examined whether hFis1, a mammalian homologue of yeast Fis1, which has been shown to participate in mitochondrial fission by an interaction with DLP1/Drp1, is also involved in peroxisomal growth and division. We show that hFis1 localizes to peroxisomes in addition to mitochondria. Through differential tagging and deletion experiments, we demonstrate that the transmembrane domain and the short C-terminal tail of hFis1 is both necessary and sufficient for its targeting to peroxisomes and mitochondria, whereas the N-terminal region is required for organelle fission. hFis1 promotes peroxisome division upon ectopic expression, whereas silencing of Fis1 by small interfering RNA inhibited fission and caused tubulation of peroxisomes. These findings provide the first evidence for a role of Fis1 in peroxisomal fission and suggest that the fission machinery of mitochondria and peroxisomes shares common components.
CD74 Is a Member of the Regulated Intramembrane Proteolysis-processed Protein Family
Authors: Becker-Herman Shirly , Arie Galit , Medvedovsky Helena , Kerem Anat , Shachar Idit
Published: August 2005

Quite a few regulatory proteins, including transcription factors, are normally maintained in a dormant state to be activated after internal or environmental cues. Recently, a novel strategy, requiring proteolytic cleavage, was described for the mobilization of dormant transcription factors. These transcription factors are initially synthesized in an inactive form, whereas “nesting” in integral membrane precursor proteins. After a cleavage event, these new active factors are released from the membrane and can migrate into the nucleus to drive regulated gene transcription. This mechanism, regulated intramembrane proteolysis (RIP), controls diverse biological processes in prokaryotes and eukaryotes in response to a variety of signals. The MHC class II chaperone, CD74 (invariant chain, Ii), was previously shown to function as a signaling molecule in several pathways. Recently, we demonstrated that after intramembranal cleavage, the CD74 cytosolic fragment (CD74-ICD) is released and induces activation of transcription mediated by the NF-κB p65/RelA homodimer and the B-cell-enriched coactivator, TAFII105. Here, we add CD74 to the growing family of RIP-processed proteins. Our studies show that CD74 ectodomain must be processed in the endocytic compartments to allow its intramembrane cleavage that liberates CD74 intracellular domain (CD74-ICD). We demonstrate that CD74-ICD translocates to the nucleus and induces the activation of the p65 member of NF-κB in this compartment.
Live Imaging ofDrosophilaBrain Neuroblasts Reveals a Role for Lis1/Dynactin in Spindle Assembly and Mitotic Checkpoint Control
Authors: Siller Karsten H. , Serr Madeline , Steward Ruth , Hays Tom S. , Doe Chris Q.
Published: August 2005

Lis1 is required for nuclear migration in fungi, cell cycle progression in mammals, and the formation of a folded cerebral cortex in humans. Lis1 binds dynactin and the dynein motor complex, but the role of Lis1 in many dynein/dynactin-dependent processes is not clearly understood. Here we generate and/or characterize mutants for Drosophila Lis1 and a dynactin subunit, Glued, to investigate the role of Lis1/dynactin in mitotic checkpoint function. In addition, we develop an improved time-lapse video microscopy technique that allows live imaging of GFP-Lis1, GFP-Rod checkpoint protein, green fluorescent protein (GFP)-labeled chromosomes, or GFP-labeled mitotic spindle dynamics in neuroblasts within whole larval brain explants. Our mutant analyses show that Lis1/dynactin have at least two independent functions during mitosis: first promoting centrosome separation and bipolar spindle assembly during prophase/prometaphase, and subsequently generating interkinetochore tension and transporting checkpoint proteins off kinetochores during metaphase, thus promoting timely anaphase onset. Furthermore, we show that Lis1/dynactin/dynein physically associate and colocalize on centrosomes, spindle MTs, and kinetochores, and that regulation of Lis1/dynactin kinetochore localization in Drosophila differs from both Caenorhabditis elegans and mammals. We conclude that Lis1/dynactin act together to regulate multiple, independent functions in mitotic cells, including spindle formation and cell cycle checkpoint release.
A Role for Jsn1p in Recruiting the Arp2/3 Complex to Mitochondria in Budding Yeast
Authors: Fehrenbacher Kammy L. , Boldogh Istvan R. , Pon Liza A.
Published: August 2005

Although the Arp2/3 complex localizes to the leading edge of motile cells, endocytic structures, and mitochondria in budding yeast, the mechanism for targeting the Arp2/3 complex to different regions in the cell is not well understood. We find that Jsn1p, a member of the PUF family of proteins, facilitates association of Arp2/3 complex to yeast mitochondria. Jsn1p localizes to punctate structures that align along mitochondria, cofractionates with a mitochondrial marker protein during subcellular fractionation, and is both protease sensitive and carbonate extractable in isolated mitochondria. Thus, Jsn1p is a peripheral membrane protein that is associated with the outer leaflet of the mitochondrial outer membrane. Jsn1p colocalized and coimmunoprecipitated with mitochondria-associated Arc18p-GFP, and purified Arp2/3 complex bound to isolated TAP-tagged Jsn1p. Moreover, deletion of JSN1 reduces the amount of Arc18p-GFP that colocalizes and is recovered with mitochondria twofold, and jsn1Δ cells exhibited defects in mitochondrial morphology and motility similar to those observed in Arp2/3 complex mutants. Thus, Jsn1p has physical interactions with mitochondria-associated Arp2/3 complex and contributes to physical and functional association of the Arp2/3 complex with mitochondria.
PREVENTIVE CARE AND INSURANCE COVERAGE
Authors: GOHMANN STEPHAN F.
Published: August 2005

This article examines how having a choice of health plans, HMO enrollment, and health status affect the use of preventive services. For preventive services use, HMO enrollment is endogenous for workers with a choice of plans, but is exogenous for workers who do not have a choice. Relative to a model that ignores the effect of a choice of plans, the effect of HMO enrollment on the use of preventive treatments is reduced. Individuals who do not have a choice of plans but are enrolled in HMOs are more likely to use preventive services than are individuals who choose HMOs. (JEL I10, I11, I12)
THE EFFECT OF YOUTH ALCOHOL INITIATION ON HIGH SCHOOL COMPLETION
Authors: Koch Steven F. , McGeary Kerry Anne
Published: August 2005

The social environment inherent in schools impacts both alcohol consumption onset and high school completion. The results reported here, based on data from the 1979–96 NLSY panels, show that the social coincidences between alcohol consumption and education are important determinants of both education completion and alcohol onset. Ignoring the social nature of these simultaneous decisions underestimates the impact of alcohol onset on education. After correcting for the presence of an endogenous positive relationship between schooling and alcohol consumption, we find that alcohol initiation before age 14 significantly reduces the probability of timeously completing high school by between 7% and 22%. (JEL I18, I21)
PASSENGER LEAKS AND THE FATE OF SMALL COMMUNITY AIR SERVICE
Authors: Phillips Owen R. , Weatherford Larry R. , Mason Charles F. , Kunce Mitch
Published: August 2005

Using airline‐booking data from Sabre, this article documents the proportion of passengers who drive and fly from a hub airport, rather than take a commuter flight. If fewer passengers leaked to a hub, community airports would have more enplanements. Price and quality factors affecting leaks are econometrically estimated for the state of Wyoming. Fare differences, distance between the local airport and hub and the proportion of regional jets making the hub connection are important determinants. Short‐run elasticities are estimated to measure the sensitivity of local air travelers to these factors. Leaks increased after September 11, 2001. (JEL L52, L93)
Two-Step Hierarchical Estimation: Beyond Regression Analysis
Authors: Achen Christopher H.
Published: August 2005

Two-step estimators for hierarchical models can be constructed even when neither stage is a conventional linear regression model. For example, the first stage might consist of probit models, or duration models, or event count models. The second stage might be a nonlinear regression specification. This note sketches some of the considerations that arise in ensuring that two-step estimators are consistent in such cases.
The PTEN/PI3K pathway governs normal vascular development and tumor angiogenesis
Authors: Hamada Koichi , Sasaki Takehiko , Koni Pandelakis A. , Natsui Miyuki , Kishimoto Hiroyuki , Sasaki Junko , Yajima Nobuyuki , Horie Yasuo , Hasegawa Go , Naito Makoto , Miyazaki Jun-ichi , Suda Toshio , Itoh Hiroshi , Nakao Kazuwa , Mak Tak Wah , Nakano Toru , Suzuki Akira
Published: August 2005

PTEN is an important tumor suppressor gene. Hereditary mutation of PTEN causes tumor-susceptibility diseases such as Cowden disease. We used the Cre-loxP system to generate an endothelial cell-specific mutation of Pten (Tie2CrePten) in mice. Tie2CrePtenflox/+ mice displayed enhanced tumorigenesis due to an increase in angiogenesis driven by vascular growth factors. This effect was partially dependent on the PI3K subunits p85α and p110γ. In vitro, Tie2CrePtenflox/+ endothelial cells showed enhanced proliferation/migration. Tie2CrePtenflox/flox mice died before embryonic day 11.5 (E11.5) due to bleeding and cardiac failure caused by impaired recruitment of pericytes and vascular smooth muscle cells to blood vessels, and of cardiomyocytes to the endocardium. These phenotypes depend strongly on p110γ rather than on p85α and were associated with decreased expression of Ang-1, VCAM-1, connexin 40, and ephrinB2 but increased expression of Ang-2, VEGF-A, VEGFR1, and VEGFR2. Pten is thus indispensable for normal cardiovascular morphogenesis and post-natal angiogenesis, including tumor angiogenesis.
RhoC is dispensable for embryogenesis and tumor initiation but essential for metastasis
Authors: Hakem Anne , Sanchez-Sweatman Otto , You-Ten Annick , Duncan Gordon , Wakeham Andrew , Khokha Rama , Mak Tak W.
Published: August 2005

The Rho proteins are Ras-related guanosine triphosphatases (GTPases) that function in cytoskeletal reorganization, cell migration, and stress fiber and focal adhesion formation. Overexpression of RhoC enhances the ability of melanoma cells to exit the blood and colonize the lungs. However, in vivo confirmation of RhoC's role in metastasis has awaited a RhoC-deficient mouse model. Here we report the generation of RhoC-deficient mice and show that RhoC is dispensable for embryonic and post-natal development. We demonstrate that loss of RhoC does not affect tumor development but decreases tumor cell motility and metastatic cell survival leading to a drastic inhibition of metastasis.
State-dependent Ras signaling and AMPA receptor trafficking
Authors: Qin Yi , Zhu Yinghua , Baumgart Joel P. , Stornetta Ruth L. , Seidenman Kenneth , Mack Volker , van Aelst Linda , Zhu J. Julius
Published: August 2005

Synaptic trafficking of AMPA-Rs, controlled by small GTPase Ras signaling, plays a key role in synaptic plasticity. However, how Ras signals synaptic AMPA-R trafficking is unknown. Here we show that low levels of Ras activity stimulate extracellular signal-regulated kinase kinase (MEK)–p42/44 MAPK (extracellular signal-regulated kinase [ERK]) signaling, whereas high levels of Ras activity stimulate additional Pi3 kinase (Pi3K)–protein kinase B (PKB) signaling, each accounting for ∼50% of the potentiation during long-term potentiation (LTP). Spontaneous neural activity stimulates the Ras–MEK–ERK pathway that drives GluR2L into synapses. In the presence of neuromodulator agonists, neural activity also stimulates the Ras–Pi3K–PKB pathway that drives GluR1 into synapses. Neuromodulator release increases with increases of vigilance. Correspondingly, Ras–MEK–ERK activity in sleeping animals is sufficient to deliver GluR2L into synapses, while additional increased Ras–Pi3K–PKB activity in awake animals delivers GluR1 into synapses. Thus, state-dependent Ras signaling, which specifies downstream MEK–ERK and Pi3K–PKB pathways, differentially control GluR2L- and GluR1-dependent synaptic plasticity.
Molecular mechanism of temperature sensing by the circadian clock of Neurospora crassa
Authors: Diernfellner Axel C.R. , Schafmeier Tobias , Merrow Martha W. , Brunner Michael
Published: August 2005

Expression levels and ratios of the long (l) and short (s) isoforms of the Neurospora circadian clock protein FREQUENCY (FRQ) are crucial for temperature compensation of circadian rhythms. We show that the ratio of l-FRQ versus s-FRQ is regulated by thermosensitive splicing of intron 6 of frq, a process removing the translation initiation site of l-FRQ. Thermosensitivity is due to inefficient recognition of nonconsensus splice sites at elevated temperature. The temperature-dependent accumulation of FRQ relative to bulk protein is controlled at the level of translation. The 5′-UTR of frq RNA contains six upstream open reading frames (uORFs) that are in nonconsensus context for translation initiation. Thermosensitive trapping of scanning ribosomes at the uORFs leads to reduced translation of the main ORF and allows adjustment of FRQ levels according to ambient temperature.
Activation/inactivation of the classical pathway of complement in non‐lesional skin of patients with systemic lupus erythematosus
Authors: Alahlafi A. , Wordsworth P. , Wojnarowska F.
Published: August 2005

Background:  The link between the lupus band and pathogenesis remains controversial, because immunoglobulins and complement components, including the membrane attack complex, can be found in both lesional and non‐lesional skin of patients with systemic lupus erythematosus (SLE). The expression of proteins that regulate complement has not been previously investigated in the skin of patients with SLE.

Aim:  The aim of this study is to compare the expression of protectin (CD59), which demonstrates the activation of the classical pathway of complement, in non‐lesional skin obtained from patients with SLE with its expression in normal skin. This may help us explain the link between the lupus band and pathogenesis of cutaneous lupus erythematosus.

Methods:  An indirect immunofluorescence technique was performed in order to provide unequivocal evidence for the activation of complement via the classical pathway and to compare the expression of CD59 in non‐lesional skin from patients with SLE with normal skin samples obtained from healthy people.

Results:  The activation of the classical pathway of complement was demonstrated in non‐lesional skin in more than 90% of SLE patients investigated in this study. Staining intensity of the complement regulatory protein CD59 was markedly increased in the majority of non‐lesional skin samples obtained from patients with SLE, compared to that from normals.

Conclusions:  CD59 is overexpressed in non‐lesional skin in which complement activation has occurred. It seems likely that an increased and continuous CD59 expression may be important for maintaining the integrity of the skin BMZ during inflammatory responses involving complement activation in SLE skin.
Primary cutaneous cribriform carcinoma: a rare apocrine tumour
Authors: Adamski Henri , Le Lan Jacky , Chevrier Stéphane , Cribier Bernard , Watier Eric , Chevrant‐Breton Jacqueline
Published: August 2005

Background:  Primary cutaneous cribriform carcinoma (PCCC) is a rare apocrine tumour occurring in middle‐aged people. This neoplasm is often located on the limbs. The histopathological diagnosis is difficult, mainly because this tumour is exceptional. We, in this study, report a patient with PCCC.

Case report:  The patient was a 37‐year‐old man who presented with a nodule of the left knee.

Results:  Histopathologic findings showed an asymmetrical deep dermal tumour with a cribriform pattern. The aggregations of neoplastic cells were interconnected and varied in size and shape. The cells were arranged in solid nests or tubular structures. In the lumina of tubules, some papillary protrusion of basophilic cells was seen. The ductal elements were lined by cuboidal or cylindric cells with images of decapitation secretion. The nuclei of the neoplastic cells were pleomorphic. A wide excision was performed with sentinel inguinal node biopsy. After a 2‐year follow‐up, neither persistence at the local site nor metastasis was observed.

Conclusions:  Clinical and pathological features of PCCC are reviewed. Differential diagnoses, including cutaneous metastasis of adenocarcinoma, adenoid basal cell carcinoma and adenoid cystic carcinoma, are discussed.
CD56 staining in Merkel cell carcinoma and natural killer‐cell lymphoma: magic bullet, diagnostic pitfall, or both?
Authors: McNiff Jennifer M. , Cowper Shawn E. , Lazova Rossitza , Subtil Antonio , Glusac Earl J.
Published: August 2005

Background:  Antibodies to CD56 label natural killer (NK) cell lymphomas and neuroendocrine tumors such as Merkel cell carcinoma (MCC). In MCC altered by crush artifact or obscured by lymphocytes, the histologic features coupled with CD56 positivity can lead to an erroneous impression of NK‐cell lymphoma.

Methods:  Eighteen cases of MCC were stained for CD56, CK20, MNF116, and pankeratin. The results were compared to histologic features and CD56 staining pattern of three NK‐cell lymphomas.

Results:  Three of 18 cases of MCC histologically resembled lymphoma, and CD56 positivity with CD3 and CD20 negativity initially raised the possibility of NK‐cell lymphoma. Two additional cases were obscured by dense inflammation, again suggesting the diagnosis of lymphoma. Seventeen of 18 MCC labeled for CD56 and an equal number stained for CK20. All MCC tested were positive for CAM5.2 (14/14) and MNF116 (17/17). Antibodies to pankeratin labeled only one of 18 MCC. Staining for CD56 was stronger in MCC than NK‐cell lymphomas.

Conclusions:  CD56 is a sensitive marker for MCC as well as for NK‐cell lymphoma, but is not specific. Importantly, CD56 positivity in crushed or inflamed biopsies of MCC may lead to an erroneous impression of NK lymphoma. Awareness of this potential pitfall will prevent misdiagnosis.
Indeterminate cell histiocytosis: fact or fiction?
Authors: Ratzinger Gudrun , Burgdorf Walter H. C. , Metze Dieter , Zelger Bettina G. , Zelger Bernhard
Published: August 2005

Abstract:  Indeterminate cell histiocytosis is a rare disorder, in which the predominant cells have the characteristics of both Langerhans cells and macrophages. We, in this study, describe 18 patients and compare them with those previously published. Most patients were adults with either solitary or multiple red‐brown papules or nodules. While most lesions were confined to the skin, both conjunctival and bony involvement was seen. Histologically, the lesions showed patterns resembling those described for xanthogranulomas, with predominantly oncocytic (nine patients), spindled (five patients), scalloped (two patients) or vacuolated (two patients) macrophages. The accompanying infiltrate was mainly lymphocytic, although eosinophils and occasionally plasma cells were seen. All lesions were positive for macrophage markers, such as KP1 (CD68) and Ki‐M1p, as well as for S‐100 protein and showed variable reactivity for CD1a. No Birbeck granules were seen ultrastructurally in one patient. Some patients shared features with sinus histiocytosis with massive lymphadenopathy. It is unclear whether this disorder is a separate entity or represents various macrophage disorders identified at various time points in the inflammatory response.
The Iron Law of What Again? Conceptualizing Oligarchy Across Organizational Forms
Authors: Leach Darcy K.
Published: August 2005

The debate around Michels's “iron law of oligarchy” over the question of whether organizations inevitably become oligarchic reaches back almost a century, but the concept of oligarchy has frequently been left underspecified, and the measures that have been employed are especially inadequate for analyzing nonbureaucratically structured organizations. A conceptual model is needed that delineates what does and does not constitute oligarchy and can be applied in both bureaucratic and nonbureaucratic settings. Definitions found in the research are inadequate for two reasons. First, treating oligarchy solely as a feature of organizational structure neglects the possibility that a powerful elite may operate outside of the formal structure. A democratic structure is a necessary precondition, but it does not guar-antee the absence of oligarchy. Second, studies that equate oligarchy with goal displacement and bureaucratic conservatism cannot account for organizations with radical goals that are nonetheless dominated by a ruling elite. This article presents a model that distinguishes between legitimate and illegitimate forms of formal and informal power to define oligarchy as a concentration of illegitimate power in the hands of an entrenched minority. The model is intended for use in organizations that are nominally democratic to determine whether a formal or informal leadership has in fact acquired oligarchic control. By providing a common framework for tracking fluctuations in the distribution and legitimacy of both formal and informal power, it is hoped that this model will facilitate a more productive bout of research on the conditions under which various forms of democratically structured organizations may be able to resist oligarchization.
Causal Effects in Education
Authors: Webbink Dinand
Published: August 2005

Abstract.  In recent years, a wave of new studies on the effects of educational interventions on student performance has emerged. The realization that inputs in the education process are endogenous is important for the validity of traditional findings. Because of ignoring endogeneity bias, all traditional estimates might be wrong. Recent studies exploit exogenous variation in interventions in education produced by controlled or natural experiments. Results generated by this methodological innovation differ substantially from the traditional findings. This article reviews this new literature, illustrates new methods for identifying causal effects of interventions in education and compares the findings with the traditional literature.
Productivity Bias Hypothesis and The Purchasing Power Parity: a review article
Authors: Bahmani‐Oskooee Mohsen , Nasir ABM
Published: August 2005

Abstract.  Productivity differentials among countries are said to be one of the major sources that contribute to the deviation of the Purchasing Power Parity‐based exchange rate from the equilibrium rate, hence the productivity bias hypothesis. Prior to last review article on the productivity bias hypothesis in 1976, almost all studies relied upon cross‐sectional regression analysis. Since then, two groups of empirical studies have emerged. While one group has employed time‐series data, the other one has used panel data. These two later groups have provided more support to the hypothesis than the earlier cross‐sectional studies. This paper reviews and criticizes each group separately and provides tables that summarize main features of each study.
Trade and Growth: Reconciling the Macroeconomic and Microeconomic Evidence
Authors: López Ricardo A.
Published: August 2005

Abstract.  Many empirical studies based on plant‐level data have found that firms that enter the export markets are more productive than non‐exporters and that this difference in productivity is achieved before firms become involved in exporting. These findings have challenged the traditional view that openness to trade increases productivity and economic growth. This article reconsiders the literature on trade, growth, and trade policies and argues that a careful examination of these new findings is consistent with the idea that exporting increases productivity and economic growth.
Isolation, Identification and Characterization of Group A Rotavirus from a Chicken: the Inner Capsid Protein Sequence shows only a Distant Phylogenetic Relationship to Most Other Avian Group A Rotaviruses
Authors: Elschner M. , Hotzel H. , Reetz J. , Diller R. , Otto P.
Published: August 2005

Rotavirus particles were identified in the intestinal content of a 35‐day‐old stunted chicken. The virus was isolated, RNA pattern was analysed and the viral genome segment 6 was sequenced. In particular, the sequence data showed a very close similarity to the chicken rotavirus isolate Ch‐1 (99.2% amino acid homology), this is distantly related to all known avian rotaviruses and supports the existence of different VP6 types amongst avian group A rotaviruses.
Genetic Diversity of Anaplasma marginale Strains from Cattle Farms in the Province of Palermo, Sicily
Authors: de la Fuente J. , Torina A. , Naranjo V. , Caracappa S. , Vicente J. , Mangold A. J. , Vicari D. , Alongi A. , Scimeca S. , Kocan K. M.
Published: August 2005

Bovine anaplasmosis, caused by the tick‐borne rickettsia Anaplasma marginale, is endemic in Sicily and results in economic loss to the cattle industry. This study was designed to characterize strains of A. marginale at the molecular level from cattle in the Province of Palermo, Sicily. Seropositivity of cattle ≥1 year old for A. marginale in the study area ranged from 62% to 100%. The observed prevalence of A. marginale infections in cattle herds ranged from 25% to 100%. Two predominant A. marginale msp4 genotypes were found. A positive correlation was found between the prevalence of infection and the presence of Rhipicephalus (Boophilus) annulatus. Phylogenetic analysis of msp4 sequences of European strains of A. marginale did not provide phylogeographical information. These results suggest that development of farm husbandry systems and vaccines for genetically heterogeneous populations of A. marginale are needed for control of anaplasmosis in this region of Sicily.
Serodiagnosis of Burkholderia mallei Infections in Horses: State‐of‐the‐art and Perspectives
Authors: Neubauer H. , Sprague L. D. , Zacharia R. , Tomaso H. , Al Dahouk S. , Wernery R. , Wernery U. , Scholz H. C.
Published: August 2005

Burkholderia mallei causes glanders or farcy in solipeds, a disease that must be reported to the OIE (Office International des Epizooties, Paris, France). The number of reported outbreaks has increased steadily during the last decade. Serodiagnosis is hampered by the considerable number of false‐positives and ‐negatives of the internationally prescribed tests. The major problem leading to low sensitivity and specificity of complement fixation test (CFT) and enzyme‐linked immunosorbent assay (ELISA) has been linked to the test antigens currently used, i.e. crude preparations of whole cells. Future perspectives for the development and evaluation of serological test kits using well‐characterized single antigens are discussed in the light of recent molecular research on B. mallei and the closely related saprozoonotic agent B. pseudomallei.
Regulatory targets for transcription factor AP2 in Xenopus embryos
Authors: Luo Ting , Zhang Yanhui , Khadka Deepak , Rangarajan Janaki , Cho Ken W. Y. , Sargent Thomas D.
Published: August 2005

The transcription factor AP2 (TFAP2) has an important role in regulating gene expression in both epidermis and neural crest cells. In order to further characterize these functions we have used a hormone inducible TFAP2α fusion protein in a Xenopus animal cap assay to identify downstream targets of this factor. The most common pattern comprised genes predominantly expressed in the epidermis. A second group was expressed at high levels in the neural crest, but all of these were also expressed in the epidermis as well as in other tissues in which TFAP2α has not been detected, suggesting modular control involving both TFAP2‐dependent and TFAP2‐independent components. In addition, a few strongly induced genes did not overlap at all in expression pattern with that of TFAP2α in the early embryo, and were also activated precociously in the experimentally manipulated ectoderm, and thus likely represent inappropriate regulatory interactions. A final group was identified that were repressed by TFAP2α and were expressed in the neural plate. These results provide further support for the importance of TFAP2α in ectoderm development, and also highlight the molecular linkage between the epidermis and neural crest in the Xenopus embryo.
Functional specification in the Drosophila endoderm
Authors: Nakagoshi Hideki
Published: August 2005

The discovery of homeobox gene clusters led us to realize that the mechanisms for body patterning and other developmental programs are evolutionally‐conserved in vertebrates and invertebrates. The endoderm contributes to the lining of the gut and associated organs such as the liver and pancreas, which are critical for physiological functions. Our knowledge of endoderm development is limited; however, recent studies suggest that cooperation between the HNF3/Fork head and GATA transcription factors is crucial for endoderm specification. It is necessary to further understand the mechanism through which cells become functionally organized. Molecular genetic analyses of the Drosophila endoderm would provide insights into this issue. During proventriculus morphogenesis, a simple epithelial tube is folded into a functional multilayered structure, while two functions of midgut copper cells (i.e. copper absorption and acid secretion) can be easily visualized. The homeobox gene defective proventriculus (dve) plays key roles in these functional specifications.