bluuebunny/crossref_metadata_2025 huggingface dataset:
Comprehension matters: a commentary on ‘A multiple process solution to the logical problem of language acquisition’
Authors: NAIGLES LETITIA R.
Published: December 2004

MacWhinney (2004) has provided a clear and welcome synthesis of many strands of the recent research addressing the logical problem of first language acquisition from a non-nativist or non-generative grammar framework. The strand that I will comment on is the one MacWhinney calls the ‘pivot’ of his proposal, namely, that acquiring a grammar is primarily a function of learning ITEM-BASEDPATTERNS (e.g. pp. 23–29, 41, passim). These item-based patterns serve a number of dominant roles within MacWhinney's proposal, including enforcing children's conservatism (thereby reducing greatly their overgeneralizations and need to recover from the same), supporting the probabilistic nature of grammar, and enabling the competition that promotes recovery from the overgeneralizations that do occur. My concern here is primarily with the first role, that of enforcing children's conservatism, and especially with the exclusive use of language PRODUCTION as the demonstrated support of this conservatism.
Gold's theorems and the logical problem of language acquisition
Authors: SCHOLZ BARBARA C.
Published: December 2004

Evaluating Brian MacWhinney's multiple ‘solutions’ to the logical problem of language acquisition requires delineating exactly what the alleged problem is. He takes it to stem from the theorems of Gold (1967), the most celebrated of which is G1.
Dynamic force spectroscopy across an individual strongly pinned vortex in a Bi2Sr2CaCu2O8+δ single crystal
Authors: Pi U. H. , Khim Z. G. , Kim D. H. , Schwarz A. , Liebmann M. , Wiesendanger R.
Published: December 2004

Using force spectroscopy in the dynamic mode at low temperature, we have measured the interaction between a magnetic tip and an individual single vortex trapped by an artificial columnar defect in a Bi2Sr2CaCu2O8+δ single crystal. From spectroscopy data obtained along a line that intersects a vortex, we get quantitative information about the vertical and lateral magnetostatic forces between tip and vortex. Particularly, we estimate the lateral dragging force exerted on the vortex by the magnetic tip to about 1.5pN.
Dynamics of light-induced FeB pair dissociation in crystalline silicon
Authors: Geerligs L. J. , Macdonald Daniel
Published: December 2004

The dynamics of light-induced dissociation of iron–boron (FeB) pairs in p-type crystalline silicon is investigated. The dissociation is observed to be a single-exponential process which is balanced with thermal repairing. The dissociation rate is proportional to the square of the carrier generation rate and the inverse square of the FeB concentration. This suggests that the dissociation process involves two recombination or electron capture events. A proportionality constant of 5×10−15s describes the dissociation rate well in the absence of other significant recombination channels. The dissociation rate decreases in the presence of other recombination channels. These results can be used for reliable detection of iron in silicon devices and materials, and for further elucidation of the electronically driven FeB dissociation reaction.
Flicker (1∕f) noise in the critical current of Josephson junctions at 0.09–4.2K
Authors: Wellstood F. C. , Urbina C. , Clarke John
Published: December 2004

We have measured the low-frequency noise in the critical current Ic of six dc superconducting quantum interference devices (SQUIDs) with resistively shunted Nb–NbOx–PbIn Josephson junctions in the temperature range T=0.09–4.2K. Each device is voltage biased, the applied flux is an integer number of flux quanta, and the current fluctuations are measured with a second dc SQUID. At low frequencies f, there is a component of the power spectrum of the critical current fluctuations given approximately by SIc(f)=CIc2T2∕Af, where A is the area of both junctions, and C≈(3.9±0.4)×10−23m2∕K2. For quantum bits based on Josephson junctions, the scaling of SIc(f) with T2 implies that the dephasing time limited by critical current l∕f noise should scale as 1∕T for temperatures down to at least 0.09K.
Optical sensor based on ultrathin films of δ-form syndiotactic polystyrene for fast and high resolution detection of chloroform
Authors: Giordano M. , Russo M. , Cusano A. , Cutolo A. , Mensitieri G. , Nicolais L.
Published: December 2004

In this work are analyzed the performances of an optoelectronic sensor based on a sensitive nanoscale film of semicrystalline syndiotactic polystyrene (sPS) with a nanoporous crystalline phase developed for fast and high resolution detection of chloroform. In particular, the change of the polymer refractive index due to chloroform sorption into the polymer layer when the sensor is exposed to CHCl3 has been used as transduction property. Reflectance measurements have been performed using a fiber optic refractometer, coated with nanometric sPS film at very low pressure of chloroform, demonstrating high sensitivity and fast-time response combined with excellent reversibility. Mass sorption experiments have also been performed on the same polymeric material with an electronic microbalance at the same conditions at which the optical sensor has been characterized. This allowed a quantitative correlation between the mass of the analyte sorbed within the polymer layer and the refractive index variation, which has been found to be essentially independent of the temperature.
Praseodymium silicate formed by postdeposition high-temperature annealing
Authors: Sakai Akira , Sakashita Shinsuke , Sakashita Mitsuo , Yasuda Yukio , Zaima Shigeaki , Miyazaki Seiichi
Published: December 2004

Praseodymium silicate (Pr silicate) has been synthesized by molecular-beam deposition of Pr2O3 layers on Si(111) substrates and subsequent high-temperature postdeposition annealing at 1000 °C. This thermal treatment drastically changes the film texture from the crystalline Pr2O3 epitaxially grown on Si, into Pr silicate with completely amorphized structures, resulting from intermixing of Si from the substrate. It was found that the electrical characteristics of Pr silicate were critically dependent on the quality of the as-deposited Pr2O3 films. A typical dielectric constant and a leakage current density of Pr silicate grown under an optimal condition were, respectively, 19.7 and 3×10−9Acm−2 at +1 V relative to the flatband voltage for an equivalent oxide thickness of 1.9 nm. Using x-ray photoelectron spectroscopy, a valence-band offset at the Pr-silicate/Si(111) interface of 2.75 eV and a band gap of 6.50 eV were obtained. The large band gap and the highly symmetric band alignment account for the observed low leakage current density.
Broadband optical limiter based on nonlinear photoinduced anisotropy in bacteriorhodopsin film
Authors: Huang Yuhua , Siganakis Georgios , Moharam M. G. , Wu Shin-Tson
Published: December 2004

Nonlinear photoinduced anisotropy in a bacteriorhodopsin film was theoretically and experimentally investigated and a broadband active optical limiter was demonstrated in the visible spectral range. A diode-pumped second harmonic yttrium aluminum garnet laser was used as a pumping beam and three different wavelengths at λ=442, 532, and 655nm from different lasers were used as probing beams. The pump and probe beams overlap at the sample. When the pumping beam is absent, the probing beam cannot transmit the crossed polarizers. With the presence of the pumping beam, a portion of the probing light is detected owing to the photoinduced anisotropy. Due to the optical nonlinearity, the transmitted probing beam intensity is clamped at a certain value, which depends on the wavelength, when the pumping beam intensity exceeds 5mW∕mm2. Good agreement between theory and experiment is found.
Pulsed three-dimensional electron spin resonance microscopy
Authors: Blank Aharon , Dunnam Curt R. , Borbat Peter P. , Freed Jack H.
Published: December 2004

A three-dimensional (3D) electron spin resonance (ESR) microimaging system, operating in pulse mode at 9GHz is presented. This microscope enables the acquisition of spatially resolved magnetic resonance signals of free-radicals in solid or liquid samples with a resolution of up to ∼3.5×7×11.4μm in 20min of acquisition. The detection sensitivity at room temperature is ∼1.2×109spins∕√Hz, which enables the measurement of ∼2×107 spins in each voxel after 60min of acquisition. The resolution and detection sensitivity are the best obtained so far for ESR at ambient conditions of temperature and pressure. This ESR microscope can be employed in the investigation of a variety of samples in the fields of botany, life sciences, and materials science.
4.25
dB
gain in a hybrid silicate/phosphate glasses optical amplifier made by wafer bonding and ion-exchange techniques
Authors: Gardillou F. , Bastard L. , Broquin J.-E.
Published: December 2004

In this letter, we present the realization of a hybrid optical amplifier composed of an erbium/ytterbium (Er3+∕Yb3+) co-doped phosphate glass wafer bonded on a silicate glass substrate. Indeed, a thin guiding phophate glass layer has been reported on an ion-exchanged channel passive waveguide by the wafer bonding technique creating a hybrid guiding structure. A 4.25dB gain for 140mW launched pump has been demonstrated with a 1.16-cm-long hybrid amplifier.
Combinatorial studies for determining properties of thin-film gold–cobalt alloys
Authors: Ramirez Ainissa G. , Saha Ranjana
Published: December 2004

A library of gold–cobalt alloys was synthesized by combinatorial methods to explore potential contact materials for microfabricated microrelays. After a compositionally graded film was deposited, it was subjected to heat treatments to create precipitates and to promote precipitation hardening. Using a high-throughput screening method, the film was then characterized for mechanical hardness, sheet resistance, composition, and microstructure by using nanoindentation, four-point probe, x-ray photoelectron spectroscopy, and transmission electron microscopy. The hardness exhibited a linear behavior from pure gold to pure cobalt from 2 to 9 GPa. The microstructure included a metastable gold–silicide with a grain size that seems dependent on the amount of cobalt. From this combinatorial method, we gain an understanding of the material’s structure–property relationship and can illuminate the link between mechanical and electrical properties to composition. This work presents the experiments and techniques for mapping material properties.
Time evolution of the electric field at electrode interfaces with conducting polymers
Authors: Taylor D. M. , Morris D. , Cambridge J. A.
Published: December 2004

Time-resolved scanning Kelvin probe microscopy (SKPM) and Raman microscopy have been used to investigate processes occurring at the interface between indium tin oxide (ITO) electrodes and inkjet printed polyethylenedioxythiophene: polystyrene sulphonic acid (PEDOT:PSS). SKPM reveals a slow, reversible polarisation process (time constant ∼12s) occurring at the electrodes caused by the drift of Na+ and∕or H+ ions in the polymer. Raman microscopy shows that the resulting field enhancement at the electrodes increases the concentration of holes in the polymer at the anode, while at the cathode there is a significant reduction in hole concentration. Such effects have implications for both the short- and long-term stability of devices utilising PEDOT:PSS.
Response of magnetic nanoparticles to microwaves
Authors: Walton Derek , Boehnel Harald , Dunlop David J.
Published: December 2004

Two important processes in ferromagnetic resonance are the first-order absorption of a photon and creation of a single magnon, and a second-order process in which the absorption of a photon results in the creation of two magnons of equal and opposite wave vector [M. Sparks, Ferromagnetic Relaxation (McGraw–Hill, New York, 1964)]. We have found that under resonance conditions for the second-order process, samples containing ∼0.1% magnetite absorb energy from the microwave field at the same rate as a solid magnetite sample. The resultant very high-energy density in the magnetic nanoparticles, coupled with a significant thermal energy barrier with the matrix, leads to a large temperature difference between the grains and their surroundings that makes it possible to magnetize and demagnetize the sample with a relatively small increase in sample temperature.
Luminescence and lasing in InGaN∕GaN multiple quantum well heterostructures grown at different temperatures
Authors: Yablonskii G. P. , Pavlovskii V. N. , Lutsenko E. V. , Zubialevich V. Z. , Gurskii A. L. , Kalisch H. , Szymakowski A. , Jansen R. H. , Alam A. , Schineller B. , Heuken M.
Published: December 2004

It was found that the decrease of the InGaN∕GaN multiple quantum well (MQW) growth temperature from 865 to 810 °C leads to a MQW emission wavelength shift from the violet to the green spectral region. The lowering of the growth temperature also promotes a decrease of the MQW photoluminescence (PL) intensity at high excitation and a disappearance of the excitonic features from the low-temperature reflection and PL spectra of GaN barriers and claddings. The laser threshold dependence on Tg is not monotonic, with the lowest value of 270kW∕cm2 at Tg=830°C. High-temperature annealing (900 °C, 30 min) leads to a twofold increase of the PL efficiency only from the InGaN QWs grown at the lowest temperature. The results allow one to explain the laser threshold behavior in terms of the heterostructure quality, the defect concentration, In clusterization, and the piezoelectric field dependence on the MQW growth temperature.
Efficient spin depolarization in ZnCdSe spin detector: an important factor limiting optical spin injection efficiency in ZnMnSe∕ZnCdSe spin light-emitting structures
Authors: Chen W. M. , Buyanova I. A. , Kayanuma K. , Chen Z. H. , Murayama A. , Oka Y. , Toropov A. A. , Sorokin S. V. , Ivanov S. V. , Kop’ev P. S.
Published: December 2004

Spin depolarization of a ZnCdSe quantum-well spin detector (SD) in ZnMnSe∕ZnCdSe light-emitting quantum structures is investigated by cw and time-resolved optical orientation spectroscopy. It is shown that spin depolarization is governed by three distinct spin relaxation processes with the corresponding polarization decay times of 850, 30, and <10ps. The dominant and the fastest process is attributed to spin relaxation accompanying energy relaxation of hot excitons (and hot carriers) within the SD, providing evidence that it can be an important source of spin loss, leading to the observed limited efficiency of optical spin injection in the structures.
Light-induced reversible conductivity changes in silicon-on-insulator nanowires
Authors: Francinelli A. , Tonneau D. , Clément N. , Abed H. , Jandard F. , Nitsche S. , Dallaporta H. , Safarov V. , Gautier J.
Published: December 2004

Silicon-on-insulator (SOI) samples are preferred for extention of the metal-oxide-silicon technology. Here, we report a reversible change in electrical conductivity in dark conditions of a 20-nm-thick SOI layer, induced by illumination. In spite of some similarities with the Staebler–Wronski effect in hydrogenated amorphous silicon, we point out important differences such as the crystalline nature of our silicon film, the lack of hydrogen and a much shorter relaxation time at ambient temperature. This time can even be reduced by application of a vertical electric field. We suggest that interface traps play a major role in this mechanism. Finally, we noticed a conductivity change between ambient light and dark conditions.
Effect of confinement on the lifetimes of shallow impurity states in quantum wells
Authors: Orlova Ekaterina E. , Harrison Paul
Published: December 2004

The effect of confinement in quantum well on the lifetimes of excited shallow impurity states is theoretically investigated. It is shown that quantum well potential causes a slower asymptotic behavior of the wave functions at large wave vectors (q−3) and may lead to an exponential increase of the transition rates due to interaction with short wavelength (λ⪡aB) acoustic phonons. The model explains experimentally observed reduction of lifetimes of impurity states in quantum wells and allows us to predict the parameters of quantum wells to maximize impurity states lifetimes.
A rare genotype of
Cryptococcus gattii
caused the cryptococcosis outbreak on Vancouver Island (British Columbia, Canada)
Authors: Kidd S. E. , Hagen F. , Tscharke R. L. , Huynh M. , Bartlett K. H. , Fyfe M. , MacDougall L. , Boekhout T. , Kwon-Chung K. J. , Meyer W.
Published: December 2004

Cryptococcus gattii
causes life-threatening infection of the pulmonary and central nervous systems in hosts with normal immunity and traditionally has been considered to be restricted geographically to tropical and subtropical climates. The recent outbreak of
C. gattii
in the temperate climate of Vancouver Island, BC, Canada, led to a collaborative investigation. The objectives of the current study were to ascertain the environmental source of the outbreak infections, survey the molecular types of the outbreak and environmental cryptococcal isolates, and determine the extent of genetic diversity among the isolates. PCR-fingerprinting and amplified fragment length polymorphism (AFLP) were used to examine the genotypes, and mating assays were performed to determine the mating type of the isolates. All outbreak and environmental isolates belonged to
C. gattii
. Concordant results were obtained by using PCR-fingerprinting and AFLP analysis. The vast majority of clinical and veterinary infections were caused by isolates of the molecular type VGII/AFLP6, but two were caused by molecular type VGI/AFLP4. All environmental isolates belonged to molecular type VGII/AFLP6. Two or three subtypes were observed within VGII/AFLP6 among outbreak and environmental isolates. All mating-competent isolates were of the α-mating type. The emergence of this usually tropical pathogen on Vancouver Island highlights the changing distribution of this genotype and emphasizes the importance of an ongoing collaborative effort to monitor the global epidemiology of this yeast.
Human Rhesus-associated glycoprotein mediates facilitated transport of NH
3
into red blood cells
Authors: Ripoche Pierre , Bertrand Olivier , Gane Pierre , Birkenmeier Connie , Colin Yves , Cartron Jean-Pierre
Published: December 2004

Rhesus (Rh) antigens are carried by a membrane complex that includes Rh proteins (D and CcEe), Rh-associated glycoproteins (RhAG), and accessory chains (LW and CD47) associated by noncovalent bonds. In heterologous expression systems, RhAG and its kidney orthologs function as ammonium transporters. In red blood cells (RBCs), it is generally accepted that NH
3
permeates by membrane lipid diffusion. We have revisited these issues by studying RBC and ghosts from human and mouse genetic variants with defects of proteins that comprise the Rh complex. In both normal and mutant cells, stopped-flow analyses of intracellular pH changes in the presence of inwardly directed methylammonium (CH
3
NH
+
3
+CH
3
NH
2
) or ammonium (NH
+
4
+NH
3
) gradients showed a rapid alkalinization phase. Cells from human and mouse variants exhibited a decrease in their kinetic rate constants that was strictly correlated to the degree of reduction of their RhAG/Rhag expression level. Rate constants were not affected by a reduction of Rh, CD47, or LW. CH
3
NH
2
/NH
3
transport was characterized by (
i
) a sensitivity to mercurials that is reversible by 2-mercaptoethanol and (
ii
) a reduction of alkalinization rate constants after bromelain digestion, which cleaves RhAG. The results show that RhAG facilitates CH
3
NH
2
/NH
3
movement across the RBC membrane and represents a potential example of a gas channel in mammalian cells. In RBCs, RhAG may transport NH
3
to detoxifying organs, like kidney and liver, and together with nonerythroid tissue orthologs may contribute to the regulation of the systemic acid–base balance.
Three-dimensional structure and organization of a receptor/signaling complex
Authors: Francis Noreen R. , Wolanin Peter M. , Stock Jeffry B. , DeRosier David J. , Thomas Dennis R.
Published: December 2004

Transmembrane signaling in bacterial chemotaxis has become an important model system for experimental and theoretical studies. These studies have provided a wealth of detailed molecular structures, including the structures of CheA, CheW, and the cytoplasmic domain of the serine receptor Tsr. How these three proteins interact to form the receptor/signaling complex remains unknown. By using EM and single-particle image analysis, we present a three-dimensional reconstruction of the receptor/signaling complex. The complex contains CheA, CheW, and the cytoplasmic portion of the aspartate receptor Tar. We observe density consistent with a structure containing 24 aspartate-receptor monomers and additional density sufficient to house the expected four CheA monomers and six CheW monomers. Within this bipolar structure are four groups of three receptor dimers that are not threefold symmetric and are therefore unlike the symmetric trimers observed in the x-ray crystal structure of the cytoplasmic domain of the serine receptor. In the latter, the interdimer contacts occur in the signaling domains near the hairpin loop. In our structure, the signaling domains within trimers appear spaced apart by the presence of CheA and CheW. This structure argues against models where one CheA and one CheW bind to the outer face of each of the dimers in the trimer. This structure of the receptor/signaling complex provides an additional basis for understanding the architecture of the large arrays of chemotaxis receptors, CheA, and CheW found at the cell poles in motile bacteria.
Critical roles of the guanylyl cyclase B receptor in endochondral ossification and development of female reproductive organs
Authors: Tamura Naohisa , Doolittle Lynda K. , Hammer Robert E. , Shelton John M. , Richardson James A. , Garbers David L.
Published: December 2004

Guanylyl cyclase B is the receptor for a small peptide (C-type natriuretic peptide) produced locally in many different tissues. To unravel the functions of the receptor, we generated mice lacking guanylyl cyclase B through gene targeting. Expression of the receptor mRNA in tissues such as bone and female reproductive organs was evident, and significant phenotypes associated with each of these tissues were apparent in null mice. A dramatic impairment of endochondral ossification and an attenuation of longitudinal vertebra or limb-bone growth were seen in null animals. C-type natriuretic peptide-dependent increases of guanylyl cyclase B activity, but not basal enzyme activity, appeared to be required for the progression of endochondral ossification. Female mice were infertile, but male mice were not. This result was due to the failure of the female reproductive tract to develop. Thus, the guanylyl cyclase B receptor is critical for the development of both bone and female reproductive organs.
Component community dynamics of larval trematodes in the freshwater snail Semisulcospira nakasekoae in the Uji River, central Japan
Authors: Urabe M. , Hinoue M
Published: December 2004

The component community of larval trematodes in the freshwater snail Semisulcospira nakasekoae (Caenogastropoda: Sorbeoconcha: Pleuroceridae) was surveyed over 13 months from April 1996 to April 1997 inclusive. Temporal and spatial fluctuation of trematode prevalence, the frequency of multiple infections, and the duration of cercarial shedding were examined as factors that might affect trematode community structure. The spatial prevalence of some species varied significantly, but the dynamics were too small to allow an explanation of the overall pattern. The prevalence of sanguinicolids fluctuated temporally, despite a stable size distribution in the host populations (> 6.0 mm shell width), suggesting the life-cycle phenology of this species. Some pairs of species had statistically positive associations, but no pairs had negative associations. This shows the importance of positive association possibly as a result of suppression of the host defensive response on trematode community structures in molluscan hosts. The length of the patent period, which is part of the persistent period, varied among trematode species, suggesting it to be one of the factors determining prevalence in the host population.
Helminth parasites of the Eurasian otterLutra lutrain southwest Europe
Authors: Torres J. , Feliu C. , Fernández-Morán J. , Ruíz-Olmo J. , Rosoux R. , Santos-Reis M. , Miquel J. , Fons R.
Published: December 2004

The helminth fauna in 109 Eurasian otters (Lutra lutraL.) from France, Portugal and Spain was analysed, together with 56 faecal samples collected in Portugal and 23 fresh stools from otters included in a reintroduction programme. Seven helminth species were found inL. lutrain southwest Europe:Phagicolasp. (Trematoda),Aonchotheca putorii,Eucoleus schvalovoj,Strongyloides lutrae,Anisakis(third stage larvae) andDirofilaria immitis(Nematoda), andGigantorhynchussp. (Acanthocephala).Eucoleus schvalovojwas the dominant species throughout southwest Europe.Strongyloides lutraewas significantly more prevalent in the Iberian Peninsula than in France. Apart from these two dominant nematodes andA. putorii, the other helminth species were incidental parasites ofL. lutrain southwest Europe. The helminth fauna ofL. lutrain southwest Europe is, in general, poorer than that reported in eastern Europe and in all other aquatic mustelids in southwest Europe.Phagicolaspecimens are reported for the first time in a non-marine wild carnivore in Europe. The prevalences ofE. schvalovojandS. lutraeobtained by necropsy were higher than those observed by coprological analysis using a formalin-ether concentration method (Ritchie). Nevertheless, the culture of fresh faeces appears to be the best method to study infection ofL. lutrabyStrongyloides.
Adult 175 kDa collagenase antigen of Setaria cervi in immunoprophylaxis against Brugia malayi in jirds
Authors: Srivastava Y. , Rathaur S. , Bhandari Y.P. , Reddy M.V.R. , Harinath B.C.
Published: December 2004

A 175 kDa antigen fraction with collagenase activity was isolated and purified from somatic extracts of adult Setaria cervi females using column chromatography involving consecutive steps of DEAE-Sepharose CL6B and Sephadex G-100. The optimum pH for 175 kDa collagenase was found to be pH 7.0. Sensitivities to a variety of inhibitors and activators indicated that the 175 kDa coIlagenolytic enzyme was metalloserine in nature. The enzyme hydrolysed a variety of protein substrates such as haemoglobin, casein, azocasein (general substrates) and collagen, FALGPA (furanoyl-acryloyl-leu-gly-pro-ala), the specific substrate of collagenase. The enzyme showed 57% inhibition by jird anti-somatic collagenase antibodies and reacted insignificantly with normal jird sera. Further analysis was undertaken on the immunoprophylactic potential of 175 kDa collagenase in inducing immunity against Brugia malayi (a human filarial parasite) in jirds (Meriones unguiculatus) in vitro and in situ. Immune sera of jirds raised against this antigen promoted partial adherence of peritoneal exudate cells to B. malayi microfilariae (mf) and infective larvae (L3) in vitro and induced partial cytotoxicity to the parasites within 48 h. The anti-S. cervi 175 kDa antigen serum was more effective in inducing cytotoxicity to B. malayi L3, than mf. In the microchambers implanted inside immune jirds, host cells could migrate and adhere to the mf and infective larvae thereby killing them partially within 48 h.
Induced eosinophilia and proliferation in Angiostrongylus cantonensis-infected mouse brain are associated with the induction of JAK/STAT1, IAP/NF-κB and MEKK1/JNK signals
Authors: Lan K.P. , Wang C.J. , Hsu J.D. , Chen K.M. , Lai S.C. , Lee H.H.
Published: December 2004

Eosinophilic meningitis or meningoencephalitis caused by Angiostrongylus cantonensis is endemic to the Pacific area of Asia, especially Taiwan, Thailand, and Japan. Although eosinophilia is an important clinical manifestation of A. cantonensis infection, the role of eosinophils in the progress of the infection remains to be elucidated. In this experiment, we show that A. cantonensis-induced eosinophilia and inflammation might lead to the induction of IAP/NF-κB, JAK/STAT1 and MEKK1/JNK signals. The phosphorylation levels of JAK and JNK, STAT1, IAP, NF-κB and MEKK1 protein products were significantly increased after 12 days or 15 days of A. cantonensis infection. However, no significant differences in MAPKs such as Raf, MEK-1, ERK1/2 and p38 expression were found between control and infected mice. The activation potency of JAK/STAT1, IAP/NF-κB and MEKK1/JNK started increasing on day 3, with significant induction on day 12 or day 15 after A. cantonensis infection. Consistent results were noted in the pathological observations, including eosinophilia, leukocyte infiltration, granulomatous reactions, and time responses in the brain tissues of infected mice. These data suggest that the development of brain injury by eosinophilia of A. cantonensis infection is associated with activation of JAK/STAT1 signals by cytokines, and/or activation of MEKK1/JNK by oxidant stress, and/or activation of NF-κB by increasing IAP expression.
Fringe Glycosyltransferases Differentially Modulate Notch1 Proteolysis Induced by Delta1 and Jagged1
Authors: Yang Liang-Tung , Nichols James T. , Yao Christine , Manilay Jennifer O. , Robey Ellen A. , Weinmaster Gerry
Published: December 2004

Fringe O-fucose-β1,3-N-acetylglucosaminyltransferases modulate Notch signaling by potentiating signaling induced by Delta-like ligands, while inhibiting signaling induced by Serrate/Jagged1 ligands. Based on binding studies, the differential effects of Drosophila fringe (DFng) on Notch signaling are thought to result from alterations in Notch glycosylation that enhance binding of Delta to Notch but reduce Serrate binding. Here, we report that expression of mammalian fringe proteins (Lunatic [LFng], Manic [MFng], or Radical [RFng] Fringe) increased Delta1 binding and activation of Notch1 signaling in 293T and NIH 3T3 cells. Although Jagged1-induced signaling was suppressed by LFng and MFng, RFng enhanced signaling induced by either Delta1 or Jagged1, underscoring the diversity of mammalian fringe glycosyltransferases in regulating signaling downstream of different ligand-receptor combinations. Interestingly, suppression of Jagged1-induced Notch1 signaling did not correlate with changes in Jagged1 binding as found for Delta1. Our data support the idea that fringe glycosylation increases Delta1 binding to potentiate signaling, but we propose that although fringe glycosylation does not reduce Jagged1 binding to Notch1, the resultant ligand–receptor interactions do not effectively promote Notch1 proteolysis required for activation of downstream signaling events.
Phosphorylation of a novel SOCS-box regulates assembly of the HIV-1 Vif-Cul5 complex that promotes APOBEC3G degradation
Authors: Mehle Andrew , Goncalves Joao , Santa-Marta Mariana , McPike Mark , Gabuzda Dana
Published: December 2004

HIV-1 Vif (viral infectivity factor) protein overcomes the antiviral activity of the DNA deaminase APOBEC3G by targeting it for proteasomal degradation. We report here that Vif targets APOBEC3G for degradation by forming an SCF-like E3 ubiquitin ligase containing Cullin 5 and Elongins B and C (Cul5-EloB-EloC) through a novel SOCS (suppressor of cytokine signaling)-box that binds EloC. Vif binding to EloC is negatively regulated by serine phosphorylation in the BC-box motif of the SOCS-box. Vif ubiquitination is promoted by Cul5 in vitro and in vivo, and requires an intact SOCS-box. Thus, autoubiquitination of Vif occurs within the assembled Vif-Cul5 complex, analogous to F-box proteins that are autoubiquitinated within their SCF (Skp1-Cullin-F-box) complex. These findings suggest mechanisms that regulate the assembly and activity of Cul5 E3 complexes through phosphorylation or autoubiquitination of the SOCS-box protein, and identify interactions between Vif and host cell proteins that may be therapeutic targets.
Selective assembly of HIV-1 Vif-Cul5-ElonginB-ElonginC E3 ubiquitin ligase complex through a novel SOCS box and upstream cysteines
Authors: Yu Yunkai , Xiao Zuoxiang , Ehrlich Elana S. , Yu Xianghui , Yu Xiao-Fang
Published: December 2004

APOBEC3G, which induces hypermutations in newly synthesized viral DNA, is suppressed by HIV-1 Vif, acting through Cul5-ElonginB-ElonginC E3 ubiquitin ligase. We have now characterized a novel SOCS box in HIV-1 Vif that mediates its interaction with ElonginC. In this SOCS box, alanine replaces the consensus cysteine in the previously identified SOCS box. This new motif was necessary but insufficient for interaction with Cul5-ElonginB-ElonginC, as two highly conserved Cys residues outside the SOCS box were required to interact with Cul5 but not ElonginC. Therefore, selective assembly with Cul5 versus Cul2 E3 may require protein interfaces besides the SOCS-box-ElonginC interaction.
Su(var) genes regulate the balance between euchromatin and heterochromatin in Drosophila
Authors: Ebert Anja , Schotta Gunnar , Lein Sandro , Kubicek Stefan , Krauss Veiko , Jenuwein Thomas , Reuter Gunter
Published: December 2004

Histone lysine methylation is an epigenetic mark to index chromosomal subdomains. In Drosophila, H3-K9 di- and trimethylation is mainly controlled by the heterochromatic SU(VAR)3-9 HMTase, a major regulator of position-effect variegation (PEV). In contrast, H3-K27 methylation states are independently mediated by the Pc-group enzyme E(Z). Isolation of 19 point mutants demonstrates that the silencing potential of Su(var)3-9 increases with its associated HMTase activity. A hyperactive Su(var)3-9 mutant, pitkinD, displays extensive H3-K9 di- and trimethylation within but also outside pericentric heterochromatin. Notably, mutations in a novel Su(var) gene, Su(var)3-1, severely restrict Su(var)3-9-mediated gene silencing. Su(var)3-1 was identified as “antimorphic” mutants of the euchromatic H3-S10 kinase JIL-1. JIL-1Su(var)3-1 mutants maintain kinase activity and do not detectably impair repressive histone lysine methylation marks. However, analyses with seven different PEV rearrangements demonstrate a general role of JIL-1Su(var)3-1 in controlling heterochromatin compaction and expansion. Our data provide evidence for a dynamic balance between heterochromatin and euchromatin, and define two distinct mechanisms for Su(var) gene function. Whereas the majority of Su(var)s encode inherent components of heterochromatin that can establish repressive chromatin structures [intrinsic Su(var)s], Su(var)3-1 reflects gain-of-function mutants of a euchromatic component that antagonize the expansion of heterochromatic subdomains [acquired Su(var)s].
Buridan's Ass, Risk, Uncertainty, and Self‐Competition: A Theory of Entrepreneurship
Authors: Khalil Elias L.
Published: December 2004

The paper defines entrepreneurship as about ‘self‐competition’, the quest to test self‐ability: Can a future self achieve greater goals than what has been so far achieved? Self‐competition involves the development of ability and, hence, ex post assessment of ability is uncertain. Such uncertainty occasions either immobilizing anxiety (Buridan's ass) or entrepreneurial action. No such uncertainty surrounds the assessment of risk probability characterizing events such as floods and stock market crashes. An observable prediction of the proposed uncertainty/risk dichotomy is that insurance, which concerns risk, cannot crowd out religion and other belief systems which appeal to uncertainty.

In diesem Papier wird Unternehmertum im Sinne von ‘Selbst‐Konkurrenz’ deftniert, als Streben, die eigenen Fähigkeiten unter Beweis zu stellen: Kann das zukünftige Ich höhere Ziele als bisher erreichen?

Selbst‐Konkurrenz beinhaltet die Entwicklung von Fähigkeiten, und daher ist deren ex post Einschätzung unsicher. Diese Unsicherheit führt entweder zu einer lähmenden Angst (Burdians Esel) oder zu unternehmerischer Aktivität. Im Gegensatz dazu ist die Einschätzung der Risikowahrscheinlichkeit von Überschwemmungen oder Kursschwankungen an der Börse nicht von einer solchen Unsicherheit geprägt. Als beobachtbare Voraussage aus der vorgeschlagenen Unsicher‐heit/Risiko‐Dichotomie heraus ergibt sich, dass eine dieses Risiko betreffende Versicherung nicht in der Lage ist, Religion und andere Glaubenssysteme, die sich auf Unsicherheit bezichen, zu verdrängen.

Ce papier définit ľesprit entrepreneur comrne ‘une concurrence de soi’, la quete d'éprouver la capacityé de soi: Est‐ce possible qu'un futur‐soi puisse achever de plus grands buts qu'il a déjà accomplis? Une concurrence de soi consiste du développcinent de sa capacityé, done, ľévaluation ex past de cette capacityé n'est pas certaine.

Une telle incertitude mène à une anxiété paralysante (ľǎne de Buridan) ou àľ action entreprenante. Une incertitude de la sorte n'entoure pas ľévaluation de la probabilityé de risque qui caractérisent les événements tels comme ľ inondation ou la chute de la Bourse. Une prédiction qu'on petit observer de la dichotomie proposée incertitude/risque, c'est que ľ assurance, qui concerne le risque, doit laisser de place aux réligions et aux autres systèmes de croyance qui invoquent ľ incertitude.
Phasing out Sector‐Specific Regulation in Competitive Telecommunications
Authors: Knieps Günter
Published: December 2004

After overall entry deregulation, regulation of market power can only be justified in local telecommunication networks as long as they constitute monopolistic bottlenecks. Technical progress leads to a gradual disappearance of monopolistic bottlenecks, pointing out the large potential for economically efficient phasing out of sector‐specific regulation. In contrast, all forms of asymmetric regulation containing an intrinsic bias towards some firms or technologies have a strong tendency towards overregulation. The new telecommunications laws in Germany and Switzerland are shown to be prominent examples of asymmetric regulatory frameworks. Since the new telecommunications law in Switzerland is less restrictive and more transparant than its German counterpart, it seems to be more suitable to tackle the potential for phasing out sector specific regulation in telecommunications.

Nach einer umfassenden Marktoffnung ist eine Marktmachtregulierung in der Zukunft lediglich noch in Ortsnetzen gerechtfertigt, solange diese monopolistische Engpassbereiche darstellen. Der technische Fortschritt in Ortsnetzen führt allerdings allmahlich zu einer Auflösung dieser Engpassbereiche und schafft dadurch ein zunehmendes Potential für die Abschaffung sektorspezifischer Regulierungseingriffe. Demgegenüber beinhalten alle Formen asymmetrischer Regulierung eine immanente Verzerrung zugunsten spezieller Firmen oder Technologien und damit einhergehend eine starke Tendenz zur Uberregulierung. Die neuen Telekommunikationsgesetze in Deutschland und in der Schweiz stellen bedeutende Beispiele für asymmetrische Regulierungsrahmen dar. Allerdings erweist sich das neue schweizerische Telekommunikationsgesetz als weniger restriktiv und transparenter als sein deutsches Gegenstück. Es ist daher zu erwarten, daß das zunehmende Potential für ein ‘phasing out' sektorspezifischer Regulierungseingriffe in der Schweiz rascher ausgeschöpft wird als in Deutschland.

A près une ouverture entière du marché de télécommunication une régularisation de la domination du marché ne sera justifiée à l'avenir que dans les réseaux locaux aussi longtemps qu'ils constituent des goulots d'étranglement monopolistiques. Le progrès technique dans les réseaux locaux mène peu à peu à la disparition des ces goulots détranglement en créant ainsi un potentiel croissant de suppression de la régularisation sécteur‐spécifique. Par contre, toutes les formes de régularisation asymétrique contenant une distorsion immanente au profit de certaines firmes ou de certaines technologies ont une forte tendance à la sur‐régularisation. Les nouvelles lois de télécommunication en Allemagne et en Suisse sont des exemples importants d'encadrements asymétriques de régularisation. Cependant, la nouvelle lot de télécommunication suisse se montre moins restrictive et plus transparente que la loi respective en Allemagne. Par conséquent, l'on peut s'attendre à ce que le potentiel croissant de suppression de régularisations sécteur‐spécifiques sera épuisé plus vite en Suisse qu'en Allemagne.
Actin filament organization in aligned prefusion myoblasts
Authors: Swailes Nathan T. , Knight Peter J. , Peckham Michelle
Published: December 2004

The organization of the actin cytoskeleton in prefusion aligning myoblasts is likely to be important for their shape and interaction. We investigated actin filament organization and polarity by transmission electron microscopy (TEM) in these cells. About 84% of the filaments counted were either found in a subplasmalemma sheet up to 0.5 µm thick that was aligned with the long axis of the cell, or in protrusions. The remaining filaments were found in the cytoplasm, where they were randomly orientated and not organized into bundles. The polarity of the subplasmalemma filaments changed progressively from one end of the cell to the other. At the ends of the cells and in protrusions, the majority of filaments were organized such that their barbed ends faced the tip of the protrusion. We did not find any actin filament bundles or stress fibres in these cells. Time‐lapse phase microscopy demonstrated that aligned cells were still actively migrating at the time of our TEM observations, and their direction of movement was restricted to the long axis of the cell group. The ability of these cells to locomote actively in the absence of actin filament bundles suggests that in these cells the subplasmalemma actin sheet contributes not only to cell shape but also to cell locomotion.
THE RE‐SCALING OF UNEVEN DEVELOPMENT IN GHANA AND INDIA
Authors: GRANT RICHARD , NIJMAN JAN
Published: December 2004

Over the past couple of decades, policies of liberalisation and deregulation have exposed formerly protected regional markets to the powerful forces of global capital. A comparative study of Ghana and India suggests that the gateway cities of Accra and Mumbai serve as the primary theatres of accumulation and as key regional engines of growth in their wider territorial economies. The regional push emanating from these urban centres entails a re‐scaling of economic growth and of uneven development at the urban, regional, and national levels. Government policies in Ghana and India emphasise the virtues of growth and largely ignore, at a risk, the accompanying spatial inequalities.
Addiction, a condition of compulsive behaviour? Neuroimaging and neuropsychological evidence of inhibitory dysregulation
Authors: Lubman Dan I. , Yücel Murat , Pantelis Christos
Published: December 2004

Aims  Addiction has been conceptualized as a shift from controlled experimentation to uncontrolled, compulsive patterns of use. Current neurobiological models of addiction emphasize changes within the brain's reward system, such that drugs of abuse ‘hijack’ this system and bias behaviour towards further drug use. While this model explains the involuntary nature of craving and the motivational drive to continue drug use, it does not explain fully why some addicted individuals are unable to control their drug use when faced with potentially disastrous consequences. In this review, we argue that such maladaptive and uncontrolled behaviour is underpinned by a failure of the brain's inhibitory control mechanisms.

Design  Relevant neuroimaging, neuropsychological and clinical studies are reviewed, along with data from our own research.

Findings  The current literature suggests that in addition to the brain's reward system, two frontal cortical regions (anterior cingulate and orbitofrontal cortices), critical in inhibitory control over reward‐related behaviour, are dysfunctional in addicted individuals. These same regions have been implicated in other compulsive conditions characterized by deficits in inhibitory control over maladaptive behaviours, such as obsessive‐compulsive disorder.

Conclusions  We propose that in chronically addicted individuals, maladaptive behaviours and high relapse rates may be better conceptualized as being ‘compulsive’ in nature as a result of dysfunction within inhibitory brain circuitry, particularly during symptomatic states. This model may help to explain why some addicts lose control over their drug use, and engage in repetitive self‐destructive patterns of drug‐seeking and drug‐taking that takes place at the expense of other important activities. This model may also have clinical utility, as it allows for the adoption of treatments effective in other disorders of inhibitory dysregulation.
Teenage drinking and the onset of alcohol dependence: a cohort study over seven years
Authors: Bonomo Yvonne A. , Bowes Glenn , Coffey Carolyn , Carlin John B. , Patton George C.
Published: December 2004

Aim  To determine whether adolescent alcohol use and/or other adolescent health risk behaviour predisposes to alcohol dependence in young adulthood.

Design  Seven‐wave cohort study over 6 years.

Participant  A community sample of almost two thousand individuals followed from ages 14–15 to 20–21 years.

Outcome measure  Diagnostic and Statistical Manual volume IV (DSM‐IV) alcohol dependence in participants aged 20–21 years and drinking three or more times a week.

Findings  Approximately 90% of participants consumed alcohol by age 20 years, 4.7% fulfilling DSM‐IV alcohol dependence criteria. Alcohol dependence in young adults was preceded by higher persisting teenage rates of frequent drinking [odds ratio (OR) 8.1, 95% confidence interval (CI) 4.2, 16], binge drinking (OR 6.7, 95% CI 3.6, 12), alcohol‐related injuries (OR 4.5 95% CI 1.9, 11), intense drinking (OR 4.8, 95% CI 2.6, 8.7), high dose tobacco use (OR 5.5, 95% CI 2.3, 13) and antisocial behaviour (OR 5.9, 95% CI 3.3, 11). After adjustment for other teenage predictors frequent drinking (OR 3.1, 95% CI 1.2, 7.7) and antisocial behaviour (OR 2.4, 95% CI 1.2, 5.1) held persisting independent associations with later alcohol dependence. There were no prospective associations found with emotional disturbance in adolescence.

Conclusion  Teenage drinking patterns and other health risk behaviours in adolescence predicted alcohol dependence in adulthood. Prevention and early intervention initiatives to reduce longer‐term alcohol‐related harm therefore need to address the factors, including alcohol supply, that influence teenage consumption and in particular high‐risk drinking patterns.
Review article: prevalence and epidemiology of gastro‐oesophageal reflux disease
Authors: Delaney B. C.
Published: December 2004

There are considerable uncertainties around the definition and the appropriate clinical diagnostic criteria for gastro‐oesophageal reflux disease (GERD), a common condition that appears to be increasing in prevalence in the Western world. Prevalence studies of GERD are hampered by whether any heartburn symptom is included, or just predominant or even ‘sole’ heartburn, and also by the time frame over which the symptoms have been evaluated. A systematic search of Medline using the keywords ‘GERD’‘prevalence’ and ‘community’ yielded three papers, two original articles and one systematic review of studies that surveyed symptoms in unselected subjects. Heartburn is a common symptom in Europe ranging from a prevalence of 38% in Northern Europe to 9% in Italy. Comparable 6‐month data from the USA suggest an even higher prevalence with a rate of 42%. GERD is also a long‐term, relapsing disorder. A population survey in Sweden found GERD symptoms over time at 18% of the population surveyed. In summary, although symptoms and quality of life improve with acid suppression therapy, costs are high and the potential benefit of long‐term treatment is rare, but serious complications of GERD are unknown.