bluuebunny/crossref_metadata_2025 huggingface dataset:
WARTS tumor suppressor is phosphorylated by Cdc2/cyclin B at spindle poles during mitosis
Authors: Morisaki Tetsuro , Hirota Toru , Iida Shin-ichi , Marumoto Tomotoshi , Hara Toshihiro , Nishiyama Yasuyuki , Kawasuzi Michio , Hiraoka Takehisa , Mimori Tatsuyuki , Araki Norie , Izawa Ichiro , Inagaki Masaki , Saya Hideyuki
Published: October 2002

Identification of physiological substrates for Cdc2/cyclin B is crucial for understanding the functional link between mitotic events and Cdc2/cyclin B activation. A human homologue of the Drosophila warts tumor suppressor, termed WARTS, is a serine/threonine kinase and a dynamic component of the mitotic apparatus. We have found that Cdc2/cyclin B forms a complex with a fraction of WARTS in the centrosome and phosphorylates the Ser613 site of WARTS during mitosis. Immunocytochemical analysis has shown that the S613‐phosphorylated WARTS appears in the spindle poles at prometaphase and disappears at telophase. Our findings suggest that Cdc/cyclin B regulates functions of WARTS on the mitotic apparatus.
Thrombopoietin acts synergistically with LIF to maintain an undifferentiated state of embryonic stem cells homozygous for a Shp‐2 deletion mutation
Authors: Xie Xiaodong , Chan Rebecca J , Yoder Mervin C
Published: October 2002

Thrombopoietin (Tpo) and its receptor, c‐mpl, are expressed in murine embryonic stem (ES) cells. ES cells are maintained in a pluripotent state by leukemia inhibitory factor (LIF) via activation of the Janus kinase (Jak)–STAT3 signaling pathway. Tpo, like LIF, activates STAT3. We report that Tpo increases the number of undifferentiated colonies derived from wild type or Shp‐2 mutant (Shp‐2Δ46–110) ES cells. Tpo plus LIF acted synergistically on the Shp‐2Δ46–110 ES cells to maintain undifferentiated colonies but no evidence of synergism via Jak–STAT3 activation was detected. Collectively, these data suggest that Tpo can play a role in preventing ES cell differentiation via Jak–STAT3 activation and perhaps via novel pathways that are enhanced in the absence of functional Shp‐2.
Robust beta estimation: Some empirical evidence
Authors: Fong Wai Mun
Published: October 2002

The effect of allowing for skewness and excess kurtosis in estimating market model betas is examined using the Generalized Student‐t (GET) Distribution. The GET Generalized the widely used Student‐t distribution by allowing for skewness as well as leptokurtosis. Using data on monthly returns of twenty‐two stocks listed on the Singapore Stock Exchange, we find that the GET provides a significantly better fit to the data than the normal distribution or the symmetric Student‐t distribution. Based on a small out‐of‐sample experiment, the GET was also found to outperform OLS and Student‐t betas in forecasting ability.
An Organizational Analysis of the Falun Gong: Structure, Communications,
Financing
Authors: Tong James
Published: October 2002

Drawing on both regime and falun gong sources, this article analyses two conflicting depictions of falun gong's organizational structure, communications system and financing base. It first presents the regime's view that falun gong was a well organized movement, with a clear hierarchical structure, a centralized administrative system, functional specialization of organizational tasks, a well-developed communications and mobilization system, and a fulsome financial base built on undue profits derived from charging excessive admissions to qigong seminars and selling falun gong publications and icons at substantial mark-ups. In stark contrast, falun gong claimed that it had no organizational structure, no membership rosters, no local offices, telephones or financial accounts; and that its adherents were prohibited from receiving remuneration for teaching falun gong, that it charged the lowest training seminars admission and cheapest prices for publications and material. The article attributes the differences to adversarial polemics, the regime's fervour to criminalize, and the falun gong's eagerness to deny those charges. Some of the discrepancies can also be explained by the status of the falun gong as an evolving and clandestine social organization with changing features and practices, survival structures and camouflage mechanisms. Both regime and falun gong could thus stake their respective claims on different manifestations of the falun gong on arguable but ambivalent evidence.
Framing Dissent in Contemporary China: Irony, Ambiguity and Metonymy
Authors: Thornton Patricia M.
Published: October 2002

Social movement theorists have posited that it is not simply the existence of grievances but the manner in which they are interpreted and transmitted that contributes to the mobilization of dissent. Research conducted largely in liberal Western polities suggests that successful social movement “frames” clearly define problems, assign blame to a specific agent and suggest courses for remedial action. Yet dissenters in repressive authoritarian or totalitarian regimes face very different risks and political opportunity structures. Two popular contentious practices in contemporary China – ironic or ambiguous doorway hangings, and the body cultivation techniques of the recently outlawed sectarian group falun gong – demonstrate that ironic, ambiguous or metonymic frames represent adaptive strategies for the articulation of dissenting views in the face of repressive state power.
Effect of frequency of milking on yield, composition and processing quality of milk
Authors: O'BRIEN BERNADETTE , RYAN GERARD , MEANEY WILLIAM J. , McDONAGH DAVID , KELLY ALAN
Published: October 2002

The objective was to determine the effect of once-daily milking (ODM) and omitting one evening milking each week (13TWM), in late lactation on milk production, composition and processability. Seventy-two cows were assigned to three treatments (ODM, 13TWM and twice-daily milking [TDM]) from 4 October to 12 December. Cows were on average 218 d into lactation at the start of the trial, and all cows were managed similarly throughout the trial. Milk yields and gross milk composition of cows on all treatments were measured, and milk samples for detailed compositional and processability analysis were collected from TDM and ODM treatments at two consecutive milkings and at one milking each week, respectively. Milk yield was significantly reduced (P<0.001) and milk fat and protein concentrations were increased (P<0·01) with ODM compared with TDM. Milk yield and fat and protein concentrations of milk from TDM and 13TWM herds were similar. Casein concentrations in ODM and TDM milks were similar, but ODM milk had a higher (P<0·05) whey protein content. Somatic cell count of ODM and TDM milks was similar. Rennet coagulation time (RCT) and curd firmness (A60) of milk were not affected by milking frequency. However, rate of curd aggregation (K20) of ODM milk was reduced (P<0·05) compared with that of TDM milk. Plasmin activity in ODM milk was numerically higher than in TDM milk, but the effect was not significant. ODM milk had higher NAGase activity than TDM milk (P<0·01). In conclusion, once daily milking reduced milk yield by 29% and did not adversely affect the processability of milk. Moreover, one evening milking per week could be eliminated without adverse effects on milk yield or composition.
The influence of artificial light on the capture of deep-water demersal fish by bottom trawling
Authors: Gordon J.D.M. , Bergstad O.A. , Pascoe P.L.
Published: October 2002

Lights were attached to the headline of a bottom trawl during a series of tows at 1000 m depth in the Rockall Trough (north-east Atlantic). There was no significant difference in the overall numerical abundance of demersal fish between the trawl catches with light and the controls with no light. A principal components analysis based on the total fish catch between the experimental and the control stations showed no segregation. At the individual species level significant differences in catch rate were found for eight species. These are discussed in relation to the small amount of available information on the visual systems of deep-sea demersal fish and their diet.
Primary production and vegetative cycle in Posidonia oceanica when in competition with the green algae Caulerpa taxifolia and Caulerpa racemosa
Authors: Dumay Olivier , Fernandez Catherine , Pergent Gérard
Published: October 2002

Vegetative annual cycle and primary production were described in the sea grass Posidonia oceanica in competition with two Ulvophycea, Caulerpa taxifolia (Cap Martin, France) and Caulerpa racemosa (Antignano, Italy). Sampling was performed at three stations exhibiting increasing levels of interaction with Caulerpa. Significant differences were observed as a function of the Caulerpa species, season and level of interaction. For each interaction, the different parameters have some seasonal variations. Any effects of the two Caulerpa species has been detected on the seasonal variability of our parameters. For all seasons, with increasing levels of interaction, the P. oceanica adult and intermediate leaf lengths, leaf index and mean age of the leaves always decrease whereas percentage of leaves having lost their apices, epiphyte biomass per unit surface area, mean number of leaves produced per shoot and per year always increase. Conversely, mean number of leaves per shoot or below-ground tissue production do not seem to be affected by Caulerpa. Finally, primary production of P. oceanica, by an increased turnover of the foliar tissues, was greater in the case of high interaction.
Additional notes on stomach contents of sperm whales Physeter macrocephalus stranded in the north-east Atlantic
Authors: Santos M.B. , Pierce G.J. , Hartmann M. García , Smeenk C. , Addink M.J. , Kuiken T. , Reid R.J. , Patterson I.A.P. , Lordan C. , Rogan E. , Mente E.
Published: October 2002

The stomach contents of seven male sperm whales Physeter macrocephalus (Odontoceti:
Physeteridae) from the north-east Atlantic were examined. One animal was stranded on 27 November
1997 near Wassenaar (the Netherlands). Four became stranded the following day, 28 November
1997, on the island of Ameland (the Netherlands); three of these had food remains
in the stomach. Samples were also examined from a whale stranded in August 1998 at
Bettyhill (Scotland) and one live-stranded in March 1996 at Tory Island, Co. Donegal
(Ireland). Finally, a sample of the stomach contents from a whale stranded near Terneuzen
(Scheldt Estuary, the Netherlands) in February 1937 was also examined.

All samples consisted almost entirely of cephalopod beaks. Some fish remains were also found in the stomach of the Wassenaar and one of the Ameland whales. The cephalopod prey were mainly oceanic species: Gonatus sp. (probably Gonatus fabricii, Oegopsida: Gonatidae) was the main prey for all the animals stranded in the Netherlands. The specimen stranded in Ireland had consumed a wider range of prey, mainly Histioteuthis bonnellii (Oegopsida: Histiotetuhidae), but also Architeuthis sp. (Oegopsida: Architeuthidae), Chiroteuthis sp. (Oegopsida: Chiroteuthidae), Teuthowenia megalops (Oegopsida: Cranchiidae) and the octopod Haliphron atlanticus (Incirrata: Alloposidae). The fish remains from the Wassenaar whale were saithe (Pollachius virens, Gadiformes: Gadidae), while remains of monkfish (Lophius sp., Lophiiformes: Lophiidae) and an unidentified fish were recorded from one of the Ameland animals.
Polarizations on abelian varieties
Authors: SILVERBERG A. , ZARHIN YU. G.
Published: October 2002

Every isogeny class over an algebraically closed field contains a principally polarized abelian variety ([10, corollary 1 to theorem 4 in section 23]). Howe ([3]; see also
[4]) gave examples of isogeny classes of abelian varieties over finite fields with no
principal polarizations (but not with the degrees of all the polarizations divisible by
a given non-zero integer, as in Theorem 1·1 below). In [17] we obtained, for all odd
primes [lscr ], isogeny classes of abelian varieties in positive characteristic, all of whose
polarizations have degree divisible by [lscr ]2. We gave results in the more general context
of invertible sheaves; see also Theorems 6·1 and 5·2 below. Our results gave the first
examples for which all the polarizations of the abelian varieties in an isogeny class
have degree divisible by a given prime. Inspired by our results in [17], Howe [5]
recently obtained, for all odd primes [lscr ], examples of isogeny classes of abelian varieties over fields of arbitrary characteristic different from [lscr ] (including number fields),
all of whose polarizations have degree divisible by [lscr ]2.
Non-commutative trigonometry and the A-polynomial of the trefoil knot
Authors: GELCA RĂZVAN
Published: October 2002

The non-commutative generalization of the A-polynomial of a knot of Cooper,
Culler, Gillet, Long and Shalen [4] was introduced in [6]. This generalization consists
of a finitely generated left ideal of polynomials in the quantum plane, the non-
commutative A-ideal, and was defined based on Kauffman bracket skein modules, by
deforming the ideal generated by the A-polynomial with respect to a parameter. The
deformation was possible because of the relationship between the skein module with
the variable t of the Kauffman bracket evaluated at −1 and the SL(2, C)-character
variety of the fundamental group, which was explained in [2]. The purpose of the
present paper is to compute the non-commutative A-ideal for the left- and right-
handed trefoil knots. As will be seen below, this reduces to trigonometric operations in
the non-commutative torus, the main device used being the product-to-sum formula
for non-commutative cosines.
Surface plasmon resonance sensor based on the measurement of differential phase
Authors: Ho H. P. , Lam W. W. , Wu S. Y.
Published: October 2002

A differential phase detection technique has been used for measuring the optical phase change associated with the surface plasmon resonance (SPR) effect that exists in a glass-metal-dielectric stack. A typical prism-coupled SPR setup was constructed and a Mach–Zehnder interferometer was used to perform interferometric analysis between the two orthogonal polarizations in the exit beam. By stepping the optical phase of the reference arm, one can measure the phase change caused by the SPR effect. Since the reference and signal beams traverse identical optical paths except for the section where phase detection is performed, we expect that this scheme can be more robust in terms of noise immunity. The interrogation area can be enlarged to enable imaging of the SPR sensing surface. Initial phase measurement obtained from a salt-water mixture is presented to demonstrate the operation of this technique. Our SPR sensing scheme provides a refractive index measurement sensitivity of 3.1×10−6 RIU which is comparable to the value reported for reflectivity-based SPR systems. The measured phase drift, which is a good indicator for the stability of the system, is within 6.6×10−3 rad/h. Within our experiments, the effect of the incident angle deviated from resonance on the sensitivity of SPR system has also been studied, thus demonstrating that the choice of incident angle is an important factor for achieving highest sensitivity.
A core-level photoionization study of furan
Authors: Rennie E. E. , Hergenhahn U. , Kugeler O. , Rüdel A. , Marburger S. , Bradshaw A. M.
Published: October 2002

We have measured the vibrationally resolved C 1s photoelectron spectrum of the aromatic heterocycle furan (C4H4O). The vibrational profile appears to be dominated by a low-frequency mode, which shows an unusually high degree of excitation for ionization of the C atoms furthest from the oxygen. Our experimental results are compared with calculations, which reveal that several different vibrational modes participate in the vibrational pattern. A well resolved C 1s satellite spectrum at a photon energy of 335 eV has also been measured, and is compared to previous experimental and theoretical results. In a separate experiment the partial electron yield (“absorption”) spectrum has been obtained in the region from just below the C 1s π* resonance up to the respective ionization thresholds. A new high intensity feature has been identified on the high-energy flank of the C 1s−1π(3b1)* resonance. With the aid of resonant Auger spectroscopy we have tentatively assigned this feature to a Rydberg resonance. We also present the C 1s and O 1s Auger spectra of furan.
Ab initio study of magnetochiral birefringence
Authors: Coriani Sonia , Pecul Magdalena , Rizzo Antonio , Jørgensen Poul , Jaszuński Michał
Published: October 2002

The magnetically induced axial birefringence of six closed-shell chiral molecules (methyloxirane, C3H6O, fluoro- and methylcyclopropanone, C3H3OF and C4H6O, carvone, C10H14O, limonene, C10H16, and proline, C5H9NO2) is determined at the Hartree–Fock wave-function level by evaluating the frequency dependent quadratic response functions entering the molecular property expression, according to Barron and Vrbancich [Mol. Phys. 51, 715 (1984)]. Both the magnetic dipole and the electric quadrupole contributions are taken into account and their relative importance is discussed. A proof of the origin independence of the magnetochiral birefringence is presented for the exact wave function and the dependence on the origin is investigated in finite basis set calculations at the Hartree–Fock level. For carvone, limonene, and proline the results are compared with recent experimental data obtained by two different experimental groups, which are in disagreement with respect to the magnitude of the magnetochiral effect. A parallel study of the natural optical rotation shows that in the three larger molecules the optical rotatory strengths are strongly affected by changes in conformations. Nonetheless the magnetochiral birefringence computed for various different conformers—although varying remarkably—is much smaller in absolute value than experimentally observed. The disagreement—of more than three orders of magnitude—between some experimental data and theory appears to be hard to reconcile and to attribute entirely to limitations in the computational approach.
An irradiation facility for Boron Neutron Capture Therapy application based on a radio frequency driven D–T neutron source and a new beam shaping assembly
Authors: Cerullo Nicola , Esposito Juan , Leung Ka Ngo , Custodero Salvatore
Published: October 2002

A line of the Boron Neutron Capture Therapy (BNCT) research program aimed at the treatment of brain tumors, carried on at the Nuclear Departments of Pisa and Genova Universities (DIMNP and DITEC), is being focused on a new, H3(d,n)4He (D–T), accelerator-based neutron source concept, developed at Lawrence Berkeley National Laboratory (LBNL). Simple and compact accelerator designs, using mixed D+ T+ ion beam with relatively low energy, ∼100 keV, have been developed which, in turn, can generate high neutron yields. New approaches have thus been started to design an epithermal neutron irradiation facility able to selectively slow the 14.1 MeV D–T neutrons down to the epithermal (1 eV–10 KeV) energy range. New neutron spectrum shifter and filtering materials, as well as different facility layout approaches have been tested. Possible beam shaping assembly models have also been designed. The research demonstrates that a D–T neutron source could be successfully implemented to provide a ∼1×109 n/cm2 s epithermal neutron flux, in spite of its hard spectrum, although a generator device, able to yield ∼1014 n/s is, at present, not yet available. The latest Monte Carlo simulation of an accelerator-based facility, which relies on a single or multiple rf driven DT fusion neutron generator, is presented.
Characterization and model of ferroelectrics based on experimental Preisach density
Authors: Cima Lionel , Laboure Eric , Muralt Paul
Published: October 2002

In this article an experimental method of characterization and modeling of ferroelectric materials is presented. The reversible and irreversible contributions of polarization are separated. The measurements of these effects are performed simultaneously giving a perfect separation. Investigations on switching behavior under different electric field strengths permit final representation of totally irreversible effects by a two-dimensional (2D) function. This function, a Preisach-type density, allows us to extract traditional information such as remanent polarization, coercive field and so on. Then, this curve is fitted to a 2D Gaussian distribution in order to provide easy implementation in simulators. Finally, a physical model is considered to interpret this experimental function in terms of switching mechanism, leading to a powerful tool for future investigation, e.g., the origin of aging.
Nonresonant two-photon mass analyzed threshold ionization and zero kinetic energy photoelectron investigation of the X̃ 2B1 ground state of CH2CO+ and CD2CO+
Authors: Wang Shiliang , Shi Yujun , Jakubek Zygmunt J. , Barnett Michael , Simard Benoit , Müller-Dethlefs Klaus , Liu Ching-Ping , Lee Yuan-Pern
Published: October 2002

Rotationally resolved nonresonant two-photon mass analyzed threshold ionization (MATI) and zero kinetic energy (ZEKE) photoelectron spectra of CH2CO+ and CD2CO+ are reported. The spectra are dominated by the origin band and totally symmetric a1 vibrations, ν4 (C=C symmetric stretch) and ν2 (C=O asymmetric stretch) for CH2CO+, and ν1 (C=O asymmetric stretch), ν3 (C=C symmetric stretch), and ν4 (CD2 scissor) for CD2CO+. In addition, several weaker bands are observed in the MATI spectra: ν3 (CH2 scissor) in CH2CO+; b1 vibrations ν5 and ν6 (C=C=O linear bend and CH2 wag) in both isotopomers; b2 vibration ν8 (CD2 rock) for CD2CO+; b2 vibration ν9 (C=C=O linear bend) for CH2CO+; as well as overtones and combination bands. Rotational structure of the origin band is dominated by three very strong ΔKa=±1 bands with 2 orders of magnitude weaker ΔKa=+3 bands. A similar ΔKa=±1 three-band pattern is observed for the a1 vibrational modes. For the b1 modes a single-band pattern resulting from the ΔKa=0 selection rule is present. Fundamental wave numbers for six vibrational modes of CH2CO+ and seven modes of CD2CO+ are determined. Rotational analysis of the partially resolved ZEKE spectra yields the ionization potentials (77539.4±2.0 cm−1 for CH2CO and 77534.3±2.0 cm−1 for CD2CO) and rotational constants for the ground states of both ketene cations.
Correlation of structure and magnetism in GaAs with embedded Mn(Ga)As magnetic nanoclusters
Authors: Moreno M. , Trampert A. , Jenichen B. , Däweritz L. , Ploog K. H.
Published: October 2002

GaAs thin films with embedded Mn(Ga)As magnetic nanoclusters have been synthesized by annealing (Ga, Mn)As diluted material grown by low-temperature molecular-beam epitaxy (MBE). The structural and magnetic properties of granular films prepared by using different annealing recipes have been investigated by x-ray diffraction, superconducting quantum interference device magnetometry, and transmission electron microscopy. Large spherical hexagonal MnAs nanocrystals are obtained when using rapid thermal annealing. Small tetrahedral zincblende Mn(Ga)As clusters result when annealing under MBE conditions. In both cases, the matrix develops a small tensile strain of similar value. The contribution from diffuse scattering to the diffraction from the granular layers is pronounced only for films with hexagonal clusters. Strong ferromagnetic behavior is observed only in films with hexagonal clusters.
Excitation energies of a molecule close to a metal surface
Authors: Corni S. , Tomasi J.
Published: October 2002

A model for the calculation of excitation energies of molecules close to a metal surface is presented. The molecule is treated at the density functional theory (DFT) or Hartree–Fock (HF) level and the excitation energies are calculated through a time dependent DFT (TDDFT) or time dependent HF (TDHF) procedure. The metal is treated as a continuous body characterized by its frequency dependent dielectric constant, taken from experiments, in the case modified to take into account nonlocal effects in the response to the metal. Such effects are accounted for by using the specular reflection model and a hydrodynamic correction to the dielectric constant. The presence of a solvent is described with the Polarizable Continuum Model. The (quasi-)electrostatic interactions between the molecule and the metal–solvent environment are treated by exploiting the integral equation formalism, numerically solved through a boundary element method. Applications of the method are given to show its numerical accuracy and the dependence of the results on the various parameters of the model (e.g., nature of the molecule, solvent, chemical nature of the metal, metal–molecule distance).
Temperature evolution of thermoreversible polymer gel electrolytes LiClO4/ethylene carbonate/poly(acrylonitrile)
Authors: Nicotera Isabella , Oliviero Cesare , Ranieri Giuseppe , Spadafora Assunta , Castriota Marco , Cazzanelli Enzo
Published: October 2002

Thermoreversible polymer gel electrolytes with ionic conductivities of about 10−3 S cm−1 at room temperature, were prepared from poly(acrylonitrile) (PAN)-ethylene carbonate (EC)-LiClO4 at different solvent/salt ratios. A temperature dependence was investigated for the electrical and mechanical properties, as well as for spectroscopic changes associate to the solvation mechanism of lithium ions in these gel. The measurements performed on this system concern ionic conductivity, study of self-diffusion coefficient by H1−NMR, Raman spectroscopy and, finally, an accurate analysis of its mechanical proprieties by rheological tests. The gels present a strong-weak gel transition at about 70 °C, independent from salt concentration hence assignable only to the polymeric matrix. However, this transition is completely reversible on cooling, being this a necessary mechanical property for industrial applications. The Raman study has pointed out an increase, on heating, of the Li+ coordination number by EC molecules, as well as a growing number of lithium ions involved in the ionic association (Li+–solvent–ClO4−) and in the Li+–CN interaction. The experimental evidences suggest an evolution of the system toward a less organized, weak gel configuration, when temperature rises above 65 °C.
Microstructure and thermoelectric properties of Cr-doped β-FeSi2 sintered with micrograins treated in radio frequency plasmas of SiH4 and GeH4 gases
Authors: Kishimoto Kengo , Nagamoto Yasuyuki , Miki Toshikatsu , Koyanagi Tsuyoshi , Matsubara Kakuei
Published: October 2002

Microstructural control by means of plasma treatment was performed on sintered Cr-doped β-FeSi2 in order to improve its thermoelectric properties. The micrograins were exposed to rf plasmas of germane (GeH4) or a mixture of germane and silane (SiH4) and were then sintered. The thermoelectric properties of the samples were investigated along with their microstructures. The results show that the plasma treatments reduced thermal conductivity and increased electrical conductivity and mobility, which led to an increase in thermoelectric figure-of-merit. In addition, the results show that the plasma treatments also formed small SiGe crystals distributed throughout the samples, removed most of the grain boundaries, and sometimes formed FeSi crystals. The relation between the changes in the thermoelectric properties and the modification of the microstructure was discussed. It was found that the microstructural modification by the plasma treatment caused favorable changes in thermoelectric properties.
Cooling rate dependence of the glass transition temperature of polymer melts: Molecular dynamics study
Authors: Buchholz Joachim , Paul Wolfgang , Varnik Fathollah , Binder Kurt
Published: October 2002

A coarse-grained bead spring model of short polymer chains is studied by constant pressure molecular dynamics (MD) simulations. Due to two competing length scales for the length of effective bonds and the energetically preferred distance between nonbonded beads, one observes a glass transition when dense melts are cooled down (as shown in previous work, at a pressure p=1 the mode coupling critical temperature is at Tc≈0.45 and the Vogel–Fulcher temperature is T0≈0.33, in Lennard-Jones units). The present work extends these studies, estimating a cooling-rate-dependent glass transition temperature Tg(Γ) by cooling the model system from T=0.6 down to T=0.3, applying cooling rates from Γ≈10−3 to Γ≈10−6 (in MD time units), and attempting to identify Tg(Γ) from a kink in the volume versus temperature or potential energy versus temperature curves. It is found that Tg(Γ) lies in the range 0.43⩽Tg(Γ)⩽0.47, for the cooling rates quoted, and the variation of Tg(Γ) for Γ is compatible with the expected logarithmic variations. We will show why a detailed distinction between competing theories on these cooling rate effects would need an excessive amount of computer time. To estimate also the melting transition temperature Tm of this model, the sytem was prepared in a crystalline configuration as an initial state and heated up. The onset of diffusion, accompanied by an isotropization of the pressure tensor was observed for Tm≈0.77. This implies that the model is suitable for studying deeply supercooled melts.
Influence of H2-annealing on the hydrogen distribution near SiO2/Si(100) interfaces revealed by in situ nuclear reaction analysis
Authors: Wilde Markus , Matsumoto Masuaki , Fukutani Katsuyuki , Liu Ziyuan , Ando Koichi , Kawashima Yoshiya , Fujieda Shinji
Published: October 2002

Employing hydrogen depth-profiling via 1H(15N,αγ)12C nuclear reaction analysis (NRA), the “native” H concentration in thin (19–41.5 nm) SiO2 films grown on Si(100) under “wet” oxidation conditions (H2+O2) was determined to be (1–2)×1019 cm−3. Upon ion-beam irradiation during NRA this hydrogen is redistributed within the oxide and accumulates in a ∼8-nm-wide region centered ∼4 nm in front of the SiO2/Si(100) interface. Annealing in H2 near 400 °C introduces hydrogen preferentially into the near-interfacial oxide region, where apparently large numbers of hydrogen trap sites are available. The amount of incorporated H exceeds the quantity necessary to H-passivate dangling Si bonds at the direct SiO2/Si(100) interface by more than one order of magnitude. The H uptake is strongly dependent on the H2-annealing temperature and is suppressed above 430 °C. This temperature marks the onset of hydrogen desorption from the near-interfacial oxide trap sites, contrasting the thermal stability of the native H, which prevails homogeneously distributed in the SiO2 films after oxidation at 900 °C. Hydrogen bound in the near-interface oxide region is not redistributed by the ion-beam irradiation, further emphasizing its different chemical interaction with the SiO2 network as opposed to the native oxide H. The mechanism of the irradiation-induced H redistribution and its possible relation to the degradation of electrically stressed electronic devices are discussed.
Investigation of ZnO epilayers grown under various Zn/O ratios by plasma-assisted molecular-beam epitaxy
Authors: Ko Hang-Ju , Yao Takafumi , Chen Yefan , Hong Soon-Ku
Published: October 2002

We have investigated ZnO epilayers grown under various Zn/O ratios by plasma-assisted molecular-beam epitaxy. The growth conditions are elucidated by a relationship between growth rate and Zn/O ratios. Surface phase diagrams are obtained by investigation of reflection high-energy electron diffraction. Hexagonal-shaped two-dimensional islands with atomic steps measured by atomic force microscopy are observed on ZnO layers grown under oxygen-rich and stoichiometric flux conditions. On the other hand, ZnO layers grown under Zn-rich conditions exhibit hexagonal pits. The x-ray rocking curve of ZnO samples grown under an oxygen-rich condition is broader than that of ZnO samples grown under stoichiometric or Zn-rich flux conditions, implying a reduction in threading dislocation density. Photoluminescence spectra reveal the strongest intensity from ZnO layers grown under stoichiometric flux conditions, compared with those grown under Zn- and oxygen-rich conditions. The relation between linewidth of the x-ray rocking curve and intensity of photoluminescence suggests that threading dislocations act as nonradiative centers. In conclusion, the Zn/O flux ratio during growth has a strong influence on the quality of ZnO epilayer surfaces, crystal structures, and optical properties.
Effect of annealing on the In and N distribution in InGaAsN quantum wells
Authors: Albrecht M. , Grillo V. , Remmele T. , Strunk H. P. , Egorov A. Yu. , Dumitras Gh. , Riechert H. , Kaschner A. , Heitz R. , Hoffmann A.
Published: October 2002

We analyze the influence of annealing on compositional fluctuations in InGaAsN quantum wells by means of composition-sensitive high-resolution transmission electron microscopy and photoluminescence. In as-grown samples, we find In-concentration fluctuations of ±5% on a length scale of 20 nm in a two-dimensional grown quantum well. No indications for N concentration fluctuations are found within the limits of resolution. Annealing homogenizes the In distribution within the well and causes diffusion of N out of the quantum well. According to our compositional analysis, the blueshift in the photoluminescence can in part be attributed to reduction in N concentration inside the well. The more homogeneous In distribution leads to a reduction in linewidth and Stokes shift.
Atomic-layer deposition of ZrO2 with a Si nitride barrier layer
Authors: Nakajima Anri , Kidera Toshirou , Ishii Hiroyuki , Yokoyama Shin
Published: October 2002

ZrO 2 thin films for gate dielectrics have been formed at low temperatures (200 °C) by an atomic-layer deposition (ALD) technique using Zr(t-OC4H9)4 and H2O source gases. An ultrathin (physical thickness Tphy of ∼0.5 nm) Si nitride layer was deposited on a Si substrate by ALD before the deposition of ZrO2. Transmission electron microscopy showed that the Si nitride barrier layer successfully suppressed the formation of a SiO2 interfacial layer. Because of the extremely uniform thickness control capability in the ultrathin region and the low thermal budget of the ALD process, the ALD process for the ZrO2/Si nitride stack structure is a promising candidate for fabricating the ultrathin gate dielectrics for sub-0.1-μm complementary metal–oxide–semiconductor transistors.
Giant magnetoresistance in 60–150-nm-wide pseudo-spin-valve nanowires
Authors: Castaño F. J. , Haratani S. , Hao Y. , Ross C. A. , Smith Henry I.
Published: October 2002

The magnetic and magnetotransport properties exhibited by arrays of 60–150-nm-wide pseudo-spin-valve (PSV) nanowires have been investigated. The starting PSV thin film consisted of sputtered NiFe (6 nm)/Cu(3.7 nm)/Co(3 nm)/Cu(3 nm), exhibiting a room temperature giant magnetoresistance (GMR) ratio of 2.5%. Large area arrays of 150-, 80-, and 60-nm-wide nanowires were patterned from this PSV film using a combination of interference lithography and ion milling. The effects of reducing the width of the wires are a monotonic decrease in the GMR ratio and the saturation magnetization, and an increase of both the resistivity of the wires and the average switching fields of the magnetic layers. On cooling the samples to 77 K, the resistivity decreases slightly and the GMR amplitude increases independently of the width of the wires. These results suggest the presence of a disordered region at the edges of the wires as a result of processing, which increases the resistivity and decreases the saturation magnetization as the wire width decreases.
A Changing Demographic Regime and Evolving Poly centric Urban Regions: Consequences for the Size, Composition and Distribution of City Populations
Authors: Champion A.G.
Published: October 2002

The demographic regime in western Europe and many other countries of the developed world is now very different from that of 30-40 years ago and is continuing to evolve. At the same time, settlement systems have been altering significantly in spatial structure, notably in terms of the emergence of polycentric urban configurations. This paper examines the nature of these two sets of changes and searches for linkages between them. First, it outlines the main features of the changing demographic regime. Secondly, it attempts to identify what constitutes 'polycentric urban regions' as opposed to traditional monocentric structures. Thirdly, it assesses how recent demographic developments relate to traditional urban structures and discusses whether they are more conformable with polycentric urban forms.
Developing Indicators to Inform Local Economic Development in England
Authors: Wong Cecilia
Published: October 2002

Based on a conceptual framework of 11 factors that are widely perceived to be the major determinants of local economic development (LED), 29 indicators were identified to measure these factors. Principal component analysis was first used to examine the structure of relationships among the compiled LED indicators for local authority districts in England and to explore the spatial patterns that emerge from the analysis. A series of multiple regression models were then calibrated to investigate the relative strengths of relationship between the LED indicators and various performance variables. The final section concludes with the key issues revealed by the findings of these multivariate analyses.
Transport Mode Choice by Commuters to Barcelona's CBD
Authors: Asensio Javier
Published: October 2002

This paper analyses the determinants of travel mode choice for suburbanised commuters in Barcelona, Spain. After describing the importance of residential suburbanisation and the parallel increase in the share of private car use by commuters into the city centre, a nested logit model of transport mode choice is estimated. The results reveal low elasticities, particularly in the case of car commuters. Values of travel time savings are high, although within the ranges obtained in the literature. It is observed that continuing suburbanisation will result in increasing the market share of rail at the expense of the private car use and, mainly, the bus, provided that accessibility to the public transport network is maintained at present levels.
Why Do People Use Alternative Retail Channels? Some Case-study Evidence from Two English Cities
Authors: Williams Colin C.
Published: October 2002

With the cultural turn/s in urban studies, participation in alternative retail channels (i.e. informal and/or second-hand modes of goods acquisition) has been reconceptualised as motivated more by the search for fun, sociality, distinction, discernment, the spectacular and so forth rather than by economic necessity. The aim of this paper is to evaluate critically this view. Drawing upon 511 interviews conducted in affluent and deprived neighbourhoods of two English cities, this is found to reflect accurately the meanings that relatively affluent populations attach to their usage of alternative retail channels. However, economic necessity remains the principal reason amongst lower-income urban populations who view their reliance on such channels when the majority does not as a sign of their exclusion from mainstream consumption practices. The paper thus concludes by calling for greater sensitivity to economic processes and recognition of the socio-spatial variations in the meanings of such channels.
Life in a 'Food Desert'
Authors: Whelan Amanda , Wrigley Neil , Warm Daniel , Cannings Elizabeth
Published: October 2002

This paper forms part of the 'Food Deserts in British Cities' project. It reports on the findings of a series of focus groups conducted with residents in the Seacroft 'food desert' (in Leeds) in the period prior to a major improvement in their food retail accessibility. The paper explores individual food shopping behaviour, consumption patterns and attitudes towards a healthy diet and, in so doing, begins to develop an understanding of how different demographic groups adapt to living within a 'food desert'. The focus is on the perceived economic and physical constraints of residents in the area, but interwoven with this are other considerations such as motivation to consider health, family responsibilities and individual smoking status.
The Evaluation of Public Service Inspection: A Theoretical Framework
Authors: Boyne George , Day Patricia , Walker Richard
Published: October 2002

Inspection is an important and growing element of the regulation of public services. We develop a theoretical framework for the evaluation of inspection and illustrate the practical relevance of this framework with reference to the new Best Value inspectorate for UK local government. The framework contains three elements that facilitate the effectiveness of an inspection system (a director, a detector and an effector), five potential problems that impede its effectiveness (resistance, ritual compliance, regulatory capture, performance ambiguity and information gaps) and a pivotal mediating variable which is the expertise of inspectors. We combine these variables into a matrix that can be used as a checklist for the evaluation of inspection and we identify hypotheses concerning the circumstances that lead to successful inspection outcomes.
Mismatch in Local Labour Markets in Central Scotland: The Neglected Role of Demand
Authors: Adams John , Greig Malcolm , McQuaid Ronald W.
Published: October 2002

This paper presents a model of mismatch unemployment in two local labour markets in Scotland. A total of seven possible sources of such unemployment are identified and examined within the context of a predominantly urban area and a mixed urban-rural area. These are contiguous travel-to-work-areas (TTWAs). The paper attempts to identify what causes recruitment difficulties and discusses the extent to which the problem is demand-induced. A survey of employer practices and attitudes is followed up by multiple regression analysis to determine the effect of these practices on vacancy duration. The analysis shows that there are certain recruitment practices and inherent characteristics of employers which result in job offers that are either unattractive or inaccessible to the unemployed. It is argued that design of policy for implementation at the local level needs to take account more explicitly of the demand side of the local labour market than has so far been evident in the UK approach to the skill mismatch issue.
Cultural Explanation of Regional Property Markets: A Critique
Authors: Ball Michael
Published: October 2002

In a recent paper in this journal, Simon Guy and John Henneberry (2000) proposed an institutional approach to property markets that emphasises exceptional behaviour on the part of particular market agents. Using this cultural approach, they claimed to have evidence that London-based property investors deliberately underinvest in British property outside southern England. This paper criticises their dismissal of pre-existing economic and institutional property market analysis and questions the validity of their empirical conclusions.
Transnational Urbanism in the Reform-era Chinese City: Landscapes from Shenzhen
Authors: Cartier Carolyn
Published: October 2002

While the conventions of area studies scholarship have historically limited landscape analysis in China, the globalisation of scholarship and the new built environments of the reform-era Chinese city invite contemporary assessment. In Shenzhen, China's leading Special Economic Zone, the planning and construction of a new city centre complex are designed to symbolise the city's transformation from a manufacturing zone to a 'world city' and to function as its service-sector core. This landscape analysis applies the perspective of transnational urbanism to assess how the effort to instantiate 'world city' status in the built environment works through plans, ideologies and representations of domestic and transnational elites to establish legitimacy. The continuing strong role of the state in China makes the production of a new city centre a state-dominated enterprise; contesting meanings of these new landscapes takes place indirectly and symbolically in the arena of the state's spiritual civilisation campaign.
Moving the Margins of Tokyo
Authors: Waley Paul
Published: October 2002

We make sense of urban space by investing it with names, names that over time accrue meanings both polyvalent at any one point in time and mutating through time. The extent and meanings of Shitamachi, one of Tokyo's central territorial concepts, have changed significantly throughout the city's history. In this paper, I first chart these changing meanings and then set the territory within the wider terrain of capital city as vehicle for the twin interests of state and capital. Urban space in Tokyo was used as a formative setting onto which to inscribe an idea of modernisation. Within this larger picture, Shitamachi was seen as representing a past vision of the city, one that was inimical to the interests of a modernising state. It became an industrial zone, a margin within the folds of central space. In recent years, a reassessment has occurred. Shitamachi is now widely celebrated as a space of communal memory and historical identity, even though its extent and meanings remain contested. The richly symbolic spaces of the imagination are thus rooted within a changing political economy.
Twenty-Eight Day Nose-Only Inhalation Toxicity Study of Resorcinol Bis-Diphenylphosphate (Fyrolflex RDP) in Rats
Authors: Henrich R. T. , Johnson W. D. , Rajendran N. , Freudenthal R. I. , Tomlinson M. J. , Aranyi C.
Published: October 2002

To evaluate the effects of repeated inhalation exposure to resorcinol bis-diphenylphosphate (Fyrolflex RDP), male and female Sprague-Dawley rats received nose-only inhalation exposure to Fyrolflex RDP for 6 h/day, 5 days/week for 4 weeks. Concentrations of Fyrolflex RDP tested were 0 (filtered air control), 0.1, 0.5, and 2.0 mg/l air. Ten rats/sex/group were euthanized on day 29; 10 additional rats/sex in the control and high-dose groups were euthanized after a 60-day recovery period. RDP induced no mortality or overt toxicity during the exposure or recovery periods. Body weight and body weight gain were reduced in high-dose male rats during exposure, but returned to control levels after 5 weeks of recovery. Absolute and relativelung weights were increased in mid-and high-dose groups after exposure, and in the high-dose group at the end of the recovery period. Relative fiver weights were increased after exposure in mid-and high-dose females and in high-dose males. Gross pathology was limited to confluent white foci in the lungs of all high-dose animals after exposure, and in 80 % of high-dose animals after the recovery period. Underlying lung histopathology after exposure consisted of alveolar histiocytosis in mid-and high-dose groups; this progressed to chronic foreign body inflammation in high-dose rats after recovery. This response is characteristic of a noncytotoxic, water-insoluble foreign material that reaches the alveolar region of the lung. On this basis, although the observed lung lesions were exposure-related, they were not considered to reflect a specific toxic response to Fyrolflex RDP. No exposure-relatedgross or microscopic pathology was identified in any other organ in any experimental group. The no-observed-effectlevel (NOEL) for RDP in this study was 0.1 mg/l.
Problems Associated with the Absence of Activity in Standard Models of Safety Pharmacology used to Assess Biologic Products
Authors: Green Martin D.
Published: October 2002

The absence of activity may represent either a true or false negative effect. If an assay is valid for the particular test article and fails to indicate activity, it is an appropriate indicator of future events. However, if the assay is insensitive or incapable of response, the test represents a form of bias, albeit unconscious. Many biological products demonstrate a specificity of response that limits the utility of commonly employed safety studies. Specificity for many biologies arises from both their physicochemical properties and their similarity to endogenous substances which are regulated in a carefully controlled manner. To overcome the issue of a lack of predictive value, various approaches may be used. For example, a multiple testing strategy of mutually reinforcing studies may be employed or safety studies may be adoptively fit to the biological circumstance.