bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics and mixing in jet/vortex interactions
Authors: Paoli R. , Laporte F. , Cuenot B. , Poinsot T.
Published: June 2003

This study describes large eddy simulations of the interaction between an exhaust jet and a trailing vortex, in the near-field of an aircraft wake. Two cases are analyzed: in the first one, typical of cruise flight, the jet and the vortex axes are sufficiently well separated to study first the jet dynamics before considering its interaction with the vortex. Dynamics and mixing are controlled both by the jet diffusion and its entrainment around the vortex core. In the second case the jet partially blows in the vortex core, making the flow similar to a Batchelor vortex. The strong perturbations injected into the core cause an instability of the system which is continuously fed by the jet elements wrapping around the core. This leads to a strong decay of angular momentum and diffusion of the core. Global mixing properties, such as plume area and global mixedness evolutions, are analyzed and two applications to environmental problems are finally discussed.
Spectroscopy and dynamics of methylamine. I. Rotational and vibrational structures of CH3NH2 and CH3ND2 in Ã states
Authors: Baek Sun Jong , Choi Kyo-Won , Choi Young S. , Kim Sang Kyu
Published: June 2003

Rovibrational structures of methylamines (CH3NH2 and CH3ND2) in predissociative Ã states (3s–n) are investigated using (1+1) resonant-enhanced two-photon ionization (R2PI) spectroscopy. A part of experimental results was briefly reported earlier [J. Chem. Phys. 117, 10057 (2002)], and full detailed results and analyses are given here. Spectral origins are determined to be 41 669 and 42 038 cm−1 for CH3NH2 and CH3ND2, respectively. Amino wagging and CH3 rocking modes are optically active, giving their respective fundamental frequencies of 636 (487) and 1008 (1012) cm−1 for CH3NH2 (CH3ND2). The CH3 moiety is found to rotate nearly freely about the C–N axis with respect to the amino group with an accurately determined torsional barrier of 5.0±0.5 cm−1 at the zero-point level of CH3ND2(Ã). The torsional barrier increases to 19.0±0.5 cm−1 at the v (ND2-wag)=1 level due to wagging-torsional mode coupling. Both internal and overall rotational fine structures are clearly resolved for the first few vibrational levels of CH3ND2(Ã), providing accurate values of vibrational frequencies and associated internal and overall rotational constants. Broad spectral features of the CH3NH2 excitation spectrum are unambiguously assigned by using the internal rotor Hamiltonian established in the analysis of the CH3ND2 excitation spectrum. Linewidths of spectral bands provide lifetimes of corresponding quantum states excited at particular rovibrational levels, giving, for example, ∼8.8 and ∼1.8 ps for zero-point and v (ND2-wag)=2 levels of the CH3ND2 (Ã) state, respectively. The lifetime of CH3NH2(Ã) is estimated to be much shorter, giving τ∼0.38 ps at the origin band. The large H/D isotope effect in lifetimes of excited states indicates that the primary dissociation channel is the N–H(D) bond dissociation and it proceeds via tunneling through a reaction barrier. Lifetimes are found to be mode specific, showing the experimental fact that energy deposition to a certain vibrational mode, which is perpendicular to the reaction coordinate, may modify the reaction barrier along the N–H(D) reaction coordinate. Ab initio results for structures and vibrational frequencies of methylamines at excited states are compared with the experiment.
The stability of free and oxidized silver clusters
Authors: Schmidt M. , Cahuzac Ph. , Bréchignac C. , Cheng Hai-Ping
Published: June 2003

The stability and the structure of small silver and silver-oxide particles are investigated by a comparison between experimentally deduced intensity relations in the evaporative ensemble limit and theoretical results of a Born–Oppenheimer local spin density molecular dynamics calculation. We have found two-dimensional (2D) structures for pure small silver particles up to seven atoms and three-dimensional (3D) above. In contrast, we found 3D structures for all oxidized clusters even the small ones. Small silver cluster therefore undergo a 2D-to-3D structural transition by oxidation. The electronic shell structure of the metallic part still persists, when the oxygen atoms are added, taking into account that each oxygen atom reduces the number of valence electrons by 2. The enhanced stability at electronic shell closings presents some unusual evaporation channels like the ejection of a single oxygen atom from Ag3O+ leading to Ag3O+→Ag3++O as the preferential decay channel.
Studies of mobility, interdiffusion, and self-diffusion in two-component mixtures using the dynamic lattice liquid model
Authors: Polanowski Piotr , Pakula Tadeusz
Published: June 2003

The dynamic lattice liquid model was implemented as a simulation algorithm for simple liquids. This model works correctly for the density factor ρ=1 and becomes a base for a parallel algorithm. Such an algorithm takes into account coincidences of elementary molecular motion attempts resulting in local cooperative structural transformations. In this paper general conditions for simulating simple liquids on various lattices are presented. Interdiffusion coefficients were directly monitored as changes of composition profiles with time for both athermal and interacting binary (AB) mixtures. In the athermal case, the coefficients of self-diffusion and interdiffusion are equal. For interacting binary mixtures the interdiffusion exhibits a thermally activated character.
Diffusion in binary mixtures and osmotic pressure gradient
Authors: Felderhof B. U.
Published: June 2003

The relation between mutual diffusion in binary mixtures and collective diffusion in colloidal suspensions is studied on the basis of irreversible thermodynamics. Emphasis is placed on the relation between the gradient of the chemical potential driving mutual diffusion and the osmotic pressure gradient and its dependence on relative particle size. The analysis is illustrated by a study of ideal solvent mixtures, isotopic mixtures, and hard-sphere mixtures. It is shown that the two Onsager transport coefficients characterizing mutual diffusion of both components are related by a symmetry relation.
Alternative statistical-mechanical descriptions of decaying two-dimensional turbulence in terms of “patches” and “points”
Authors: Yin Z. , Montgomery D. C. , Clercx H. J. H.
Published: June 2003

Numerical and analytical studies of decaying, two-dimensional Navier–Stokes (NS) turbulence at high Reynolds numbers are reported. The effort is to determine computable distinctions between two different formulations of maximum entropy predictions for the decayed, late-time state. Though these predictions might be thought to apply only to the ideal Euler equations, there have been surprising and imperfectly understood correspondences between the long-time computations of decaying states of NS flows and the results of the maximum entropy analyses. Both formulations define an entropy using a somewhat ad hoc discretization of vorticity into “particles.” Point-particle statistical methods are used to define an entropy, before passing to a mean-field approximation. In one case, the particles are delta-function parallel “line” vortices (“points,” in two dimensions), and in the other, they are finite-area, mutually exclusive convected “patches” of vorticity which only in the limit of zero area become “points.” The former are assumed to obey Boltzmann statistics, and the latter, Lynden-Bell statistics. Clearly, there is no unique way to reach a continuous, differentiable vorticity distribution as a mean-field limit by either method. The simplest method of taking equal-strength points and equal-strength, equal-area patches is chosen here, no reason being apparent for attempting anything more complicated. In both cases, a nonlinear partial differential equation results for the stream function of the “most probable,” or maximum entropy, state, compatible with conserved total energy and positive and negative velocity fluxes. These amount to generalizations of the “sinh-Poisson” equation which has become familiar from the “point” formulation. They have many solutions and only one of them maximizes the entropy from which it was derived, globally. These predictions can differ for the point and patch discretizations. The intent here is to use time-dependent, spectral-method direct numerical simulation of the Navier–Stokes equation to see if initial conditions which should relax toward the different late-time states under the two formulations actually do so.
The constitutive relation of suspensions of noncolloidal particles in viscous fluids
Authors: Mauri Roberto
Published: June 2003

The motion of noncolloidal particles convected by a nonhomogeneous and nonstationary viscous fluid flow is investigated, assuming that inertial effects can be neglected. It appears that the particle volumetric flux is the sum of a convective part, VEφ, and a diffusive term, −Dself⋅∇φ, where VE is the Eulerian mean velocity of a test particle, φ is the particle volume fraction, and Dself is the coefficient of self-diffusion. The latter measures the local temporal growth of the mean square displacement of a tracer particle from its average position and can be written as Dself(r)=D(r,r), where the cross-diffusion tensor D(r1,r2) is the time integral of the velocity cross-correlation function. On the other hand, the Eulerian mean velocity VE is the sum of the coarse-grained average particle velocity, V̄, and a drift velocity, Vd(r)=−[(∂/∂r2)⋅DT(r,r2)]r2=r. This last term, which is identically zero when the suspended particles are passive tracers, indicates that the suspended particles tend to move toward regions with smaller diffusivities. This result demonstrates that the motion of each suspended particle is a random process satisfying a generalized nonlinear Langevin equation, where the fluctuating term is described through the cross diffusivity D.
Sensitive detection of irreversible switching in a single FePt nanosized dot
Authors: Kikuchi N. , Okamoto S. , Kitakami O. , Shimada Y. , Fukamichi K.
Published: June 2003

Magnetization of an isolated single dot as small as 60 nm in diameter fabricated from a single crystal L10-FePt(001) film has been measured by detection of the anomalous Hall effect in the temperature range from 10 to 300 K. Over the whole temperature range, the dots with diameter ranging from 60 nm to 12 μm exhibit perfect rectangular magnetization loops with coercivity almost constant regardless of the very large difference in diameter. The activation energy has been evaluated to be about 4×10−19 J, equivalent to the domain-wall energy times the square of the domain-wall thickness, suggesting that the magnetization reversals are initiated by nucleation of reversed embryo with the dimension of the exchange length.
Wavelength selection with coupled surface plasmon waves
Authors: Wang Yu
Published: June 2003

A process by which optical wavelengths can be selected by changing coupling distance of two surface plasmon waves is reported. When two surface plasmon waves are excited at metal/air/metal interfaces, coupling of the two surface plasmon waves will only allow a range of certain wavelengths to transmit. This wavelength selection depends on thickness of the air gap, and it does not have repeated passbands at harmonics. This phenomenon can be used to build broad-range tunable filters and spectrometers. Experiment showed the peak transmission wavelength could be continuously tuned from 400 to 900 nm with different voltages.
Effect of thermal annealing on the lifetime of polymer light-emitting diodes
Authors: Kim Jinook , Lee Jaeyoon , Han C. W. , Lee N. Y. , Chung In-Jae
Published: June 2003

Thermal annealing of a polymer light-emitting diode (PLED) is shown to result in a remarkable improvement in the long-term stability of the device. The annealing for such a PLED has to be layer-specific in that the annealing should be carried out for the layer with the lowest glass transition temperature (Tg) to harvest the benefits of annealing. Annealing of this key layer, which is usually the emitting layer, can enhance the thermal stability of the device. The best half-life is obtained at an annealing temperature above the Tg of emitting polymer. It is shown that the annealing of the emitting polymer layer results in a more than an order of magnitude increase in the half-life, in spite of a decrease in the efficiency of the device as the annealing temperature increases.
Enhanced absorbance of a strained nanoscale Si-layered system
Authors: Kuznicki Z. T. , Ley M.
Published: June 2003

Si modifications implemented at the nanoscale lead to optoelectronic and photovoltaic effects that can widen applications of conventional Si devices. The investigation exploits charge carrier and photon flux transformations at a so-called carrier collection limit. Comparison of the collection efficiencies of the same sample with and without a buried nanosystem allows a better understanding of the optical (absorbance) and electronic (carrier collection) behaviors. Experimental evidence for enhanced absorbance of a strained nanoscale Si-layered system has been found.
High-conductivity n-AlGaN with high Al mole fraction grown by metalorganic vapor phase deposition
Authors: Pophristic M. , Guo S. P. , Peres B.
Published: June 2003

Highly-conductive and crack-free n-Al0.6Ga0.4N films with thickness up to 1 μm were achieved by using high-temperature AlN or AlGaN/AlN superlattice (SL) buffer layers. Room-temperature Hall measurements show the highest electron concentration of 3.5×1018 cm−3 with mobility of 25 cm2/V s. Electron mobility was increased from 25 to 35 cm2/V s by introducing the AlGaN/AlN SL buffer layer. Second ion mass spectroscopy indicates that there is high oxygen doping concentration in the film, and that the film resistivity decreases with increasing oxygen concentration from 1×1017 to ∼1×1019 cm−3.
Enhancement of Schottky barrier height on AlGaN/GaN heterostructure by oxidation annealing
Authors: Jeon Chang Min , Lee Jong-Lam
Published: June 2003

The effect of preannealing of AlGaN under an oxygen ambient on the improvement of the Schottky barrier height on an AlGaN/GaN heterostructure was studied using synchrotron radiation photoemission spectroscopy. The oxidation annealing increased the Schottky barrier height from 0.59 to 0.84 eV, and dramatically reduced the reverse leakage current. The group-III elements (Ga, Al) outdiffused to the surface to form group-III oxides during the annealing, leaving group-III vacancies behind. The surface Fermi level shifted to the energy levels of group-III vacancies, leading to the enhancement of Schottky properties of AlGaN.
In
1−x
Mn
x
Sb
—a narrow-gap ferromagnetic semiconductor
Authors: Wojtowicz T. , Cywiński G. , Lim W. L. , Liu X. , Dobrowolska M. , Furdyna J. K. , Yu K. M. , Walukiewicz W. , Kim G. B. , Cheon M. , Chen X. , Wang S. M. , Luo H.
Published: June 2003

A narrow-gap ferromagnetic In1−xMnxSb semiconductor alloy was grown by low-temperature molecular-beam epitaxy on CdTe/GaAs hybrid substrates. Ferromagnetic order in In1−xMnxSb was unambiguously established by the observation of clear hysteresis loops both in direct magnetization measurements and in the anomalous Hall effect, with Curie temperatures TC ranging up to 8.5 K. The observed values of TC agree well with the existing models of carrier-induced ferromagnetism.
Effects of interfacial nitrogen on the structural and electrical properties of ultrathin ZrO2 gate dielectrics on partially strain-compensated SiGeC/Si heterolayers
Authors: Mahapatra R. , Maikap S. , Lee Je-Hun , Kar G. S. , Dhar A. , Hwang Nong-M. , Kim Doh-Y. , Mathur B. K. , Ray S. K.
Published: June 2003

The interfacial characteristics of high-κ ZrO2 on O2 and N2O-plasma-treated Si0.69Ge0.3C0.01 surfaces have been investigated using secondary ion mass spectroscopy and x-ray photoelectron spectroscopy. N2O-plasma-treated films show the formation of a nitrogen-rich Zr–germano–silicate interfacial layer between the deposited ZrO2 and SiGeC films. The N-treated film has a higher accumulation capacitance (∼1200 pF), lower leakage current density (7×10−9 A/cm2@−1 V), higher breakdown field (∼11 MV/cm), and higher interfacial layer dielectric constant (∼10) than that of the non-nitrogen-treated films. Relatively lower positive trap charge generated by a constant current stressing in N-incorporated dielectric films makes it attractive for scaled metal–oxide–semiconductor field-effect transistor applications.
Submicron periodically poled flux-grown KTiOPO4
Authors: Canalias C. , Pasiskevicius V. , Clemens R. , Laurell F.
Published: June 2003

A submicron domain grating has been created in a bulk ferroelectric. Electron-beam lithography and electric-field poling were used to fabricate the 800 nm period grating in a 0.5-mm-thick flux-grown KTiOPO4 sample. The domain structure was characterized with an atomic force microscope and was used to demonstrate electrically amplitude adjustable Bragg reflections.
In situ x-ray diffraction study on AgI nanowire arrays
Authors: Wang Yinhai , Ye Changhui , Wang Guozhong , Zhang Lide , Liu Yanmei , Zhao Zhongyan
Published: June 2003

The AgI nanowire arrays were prepared in the ordered porous alumina membrane by an electrochemical method. Transmission electron microscopy observation shows that the AgI nanowires are located in the channels of the alumina membrane. In situ x-ray diffractions show that the nanowire arrays possess hexagonal close-packed structure (β-AgI) at 293 K, orienting along the (002) plane, whereas at 473 K, the nanowire arrays possess a body-centered cubic structure (α-AgI), orienting along the (110) plane. The AgI nanowire arrays exhibit a negative thermal expansion property from 293 to 433 K, and a higher transition temperature from the β to α phase. We ascribe the negative thermal expansion behavior to the phase transition from the β to α phase, and the elevated transition temperature to the radial restriction by the channels of alumina membrane.
Microscopic mechanisms of ablation and micromachining of dielectrics by using femtosecond lasers
Authors: Jia T. Q. , Xu Z. Z. , Li X. X. , Li R. X. , Shuai B. , Zhao F. L.
Published: June 2003

We report measurements of damage threshold and ablation depth for SiO2 and CaF2 irradiated under lasers at wavelengths of 800 and 400 nm for duration of 45–800 fs. These results can be well understood by using a developed avalanche model. The model includes the production of conduction band electrons (CBEs), laser energy deposition, and CBE diffusion. The evolution of microexplosion is investigated based on this model.
Quantum cascade lasers grown by metalorganic vapor phase epitaxy
Authors: Roberts J. S. , Green R. P. , Wilson L. R. , Zibik E. A. , Revin D. G. , Cockburn J. W. , Airey R. J.
Published: June 2003

We report the growth of GaAs-based quantum cascade lasers using atmospheric pressure metalorganic vapor phase epitaxy. The necessary control of interface abruptness and layer thickness uniformity throughout the structure has been achieved using a horizontal reactor in combination with individually purged vent/run valves. A low-temperature threshold current density of 10 kA/cm2 and maximum operating temperature of 140 K have been measured. These performance levels are comparable with early GaAs-based devices grown using molecular-beam epitaxy. The measured emission wavelength (λ∼11.8 μm) is approximately 3-μm longer than the calculated transition wavelength, which we explain using a model incorporating compositional grading of the active region barriers.
Dilute LaB6 nanoparticles in polymer as optimized clear solar control glazing
Authors: Schelm Stefan , Smith Geoff B.
Published: June 2003

Window samples with a LaB6 nanoparticle-doped polymer laminate were tested for their performances in the reduction of solar heat gain. The near-infrared absorption, caused by the excitation of surface plasmons, was modeled using an average ellipsoid approach, including a size-induced broadening of the Drude part of the dielectric function. The resonance positions are well reproduced by this method and the size effect broadens the bulk resonance to an extent observed in the sample spectra. Additional broadening and spectral features observed in the absorption of the samples are attributed to shape and orientation effects.
Validity and repeatability of a simple index derived from the short physical activity questionnaire used in the European Prospective Investigation into Cancer and Nutrition (EPIC) study
Authors: Wareham Nicholas J , Jakes Rupert W , Rennie Kirsten L , Schuit Jantine , Mitchell Jo , Hennings Susie , Day Nicholas E
Published: June 2003

Objective:

To assess the validity and repeatability of a simple index designed to rank participants according to their energy expenditure estimated by self-report, by comparison with objectively measured energy expenditure assessed by heart-rate monitoring with individual calibration.

Design:

Energy expenditure was assessed over one year by four separate episodes of 4-day heart-rate monitoring, a method previously validated against whole-body calorimetry and doubly labelled water. Cardio-respiratory fitness was assessed by four repeated measures of sub-maximum oxygen uptake. At the end of the 12-month period, participants completed a physical activity questionnaire that assessed past-year activity. A simple four-level physical activity index was derived by combining occupational physical activity together with time participating in cycling and other physical exercise (such as keep fit, aerobics, swimming and jogging).

Subjects:

One hundred and seventy-three randomly selected men and women aged 40 to 65 years.

Results:

The repeatability of the physical activity index was high (weighted kappa = 0.6, P < 0.0001). There were positive associations between the physical activity index from the questionnaire and the objective measures of the ratio of daytime energy expenditure to resting metabolic rate (P = 0.003) and cardio-respiratory fitness (P = 0.001). As an indirect test of validity, there was a positive association between the physical activity index and the ratio of energy intake, assessed by 7-day food diaries, to predicted basal metabolic rate.

Conclusions:

The summary index of physical activity derived from the questions used in the European Prospective Investigation into Cancer and Nutrition (EPIC) study suggest it is useful for ranking participants in terms of their physical activity in large epidemiological studies. The index is simple and easy to comprehend, which may make it suitable for situations that require a concise, global index of activity.
The association between red and processed meat consumption and iron intakes and status among British adults
Authors: Gibson Sigrid , Ashwell Margaret
Published: June 2003

Objective:

To examine the association between consumption of red and processed meat (RPM) and iron intakes and status in adults.

Design:

Further analysis of the Dietary and Nutritional Survey of British Adults, a cross-sectional study of 2197 adults aged 16–64 years carried out in 1986/7.

Subjects and methods:

Adults (836 men and 838 women) with serum ferritin measurements, who were not taking iron supplements, were classified into four groups according to RPM consumption (from 7-day weighed records). Iron absorbed was estimated from equations based on haem and non-haem iron and the influence of iron stores.

Results:

Women who ate least meat (<90gday-1) had three times the risk of a low iron intake (below the Lower Reference Nutrient Intake) compared with high consumers of RPM (>140gday-1). Men who ate no RPM also had a higher risk of low iron intake. Using an estimate of minimal values for iron losses, there was a twofold difference in the potential risk of negative iron balance between women non-RPM consumers and high RPM consumers. Status measurements indicated that, among women, anaemia was least prevalent (6%) among high consumers compared with 12–14% among average RPM consumers. Inverse trends were also observed for serum ferritin in both sexes.

Conclusions:

Low consumption of RPM has implications for iron intakes and iron status in men and women, since the risk of negative iron balance and its consequences are increased. Dietary messages must consider these implications and provide appropriate advice.
Adaptation of international nutrition databases and data-entry system tools to a specific population
Authors: Shai Iris , Vardi Hillel , Shahar Danit R , Azrad Ayelet B , Fraser Drora
Published: June 2003

Objective:

To develop a nutritional dietary intake database based on available reliable international nutritional databases adapted to the local needs of a specific population.

Design:

The Negev Nutritional Study (NNS) is a survey of a random sample of the Negev population regarding their dietary intake using 24-hour dietary recalls. A nutritional database for the Israeli population was developed based on adaptation and modification of the US Department of Agriculture's database. A data-entry system was developed based on the logic of the US Food Information Analysis System. The system was designed as bilingual (English and Hebrew). Local foods and recipes were collected during the NNS, which included 1465 24-hour diet interviews.

Results:

During the course of the NNS, 383 basic Israeli recipes were constructed. In total 1362 Israeli products were added to the database, and each was given a code, specific gravity and portion size. Most of the added products were cereals and grains and dairy products. The added recipes were collected from the interviewees in the NNS and from the most popular cookbooks.

Conclusions:

This paper describes the process undertaken to develop an Israeli food composition database as well as the data-entry system. This knowledge may aid other research groups in developing a computerised, nation-specific nutritional database and data-entry system adapted to their own specific local needs.
VEGF guides angiogenic sprouting utilizing endothelial tip cell filopodia
Authors: Gerhardt Holger , Golding Matthew , Fruttiger Marcus , Ruhrberg Christiana , Lundkvist Andrea , Abramsson Alexandra , Jeltsch Michael , Mitchell Christopher , Alitalo Kari , Shima David , Betsholtz Christer
Published: June 2003

Vascular endothelial growth factor (VEGF-A) is a major regulator of blood vessel formation and function. It controls several processes in endothelial cells, such as proliferation, survival, and migration, but it is not known how these are coordinately regulated to result in more complex morphogenetic events, such as tubular sprouting, fusion, and network formation. We show here that VEGF-A controls angiogenic sprouting in the early postnatal retina by guiding filopodial extension from specialized endothelial cells situated at the tips of the vascular sprouts. The tip cells respond to VEGF-A only by guided migration; the proliferative response to VEGF-A occurs in the sprout stalks. These two cellular responses are both mediated by agonistic activity of VEGF-A on VEGF receptor 2. Whereas tip cell migration depends on a gradient of VEGF-A, proliferation is regulated by its concentration. Thus, vessel patterning during retinal angiogenesis depends on the balance between two different qualities of the extracellular VEGF-A distribution, which regulate distinct cellular responses in defined populations of endothelial cells.
Lipolysis
Authors: Birnbaum Morris J.
Published: June 2003

Successful adaptation to starvation in mammals depends heavily on the regulated mobilization of fatty acids from triacylglycerols stored in adipose tissue. Although it has long been recognized that cyclic AMP represents the critical second messenger and hormone-sensitive lipase (HSL)**Abbreviations used in this paper: ADRP, adipocyte differentiation-related protein; HSL, hormone-sensitive lipase; PKA, protein kinase A; TAG, triacylglycerol. the rate-determining enzyme for lipolysis, simple activation of the enzyme has failed to account for the robust augmentation of fatty release in response to physiological agonists. In this issue, Sztalryd et al. (2003) provide convincing support to the notion that the subcellular compartmentalization of lipase also regulates lipolysis, and, more importantly, that proteins other than HSL are localized to the lipid droplet and are indispensable for its optimal hydrolysis.
Calmodulin Mediates Ca2+-dependent Modulation of M-type K+ Channels
Authors: Gamper Nikita , Shapiro Mark S.
Published: June 2003

To quantify the modulation of KCNQ2/3 current by [Ca2+]i and to test if calmodulin (CaM) mediates this action, simultaneous whole-cell recording and Ca2+ imaging was performed on CHO cells expressing KCNQ2/3 channels, either alone, or together with wild-type (wt) CaM, or dominant-negative (DN) CaM. We varied [Ca2+]i from <10 to >400 nM with ionomycin (5 μM) added to either a 2 mM Ca2+, or EGTA-buffered Ca2+-free, solution. Coexpression of wt CaM made KCNQ2/3 currents highly sensitive to [Ca2+]i (IC50 70 ± 20 nM, max inhibition 73%, n = 10). However, coexpression of DN CaM rendered KCNQ2/3 currents largely [Ca2+]i insensitive (max inhibition 8 ± 3%, n = 10). In cells without cotransfected CaM, the Ca2+ sensitivity was variable but generally weak. [Ca2+]i modulation of M current in superior cervical ganglion (SCG) neurons followed the same pattern as in CHO cells expressed with KCNQ2/3 and wt CaM, suggesting that endogenous M current is also highly sensitive to [Ca2+]i. Coimmunoprecipitations showed binding of CaM to KCNQ2–5 that was similar in the presence of 5 mM Ca2+ or 5 mM EGTA. Gel-shift analyses suggested Ca2+-dependent CaM binding to an “IQ-like” motif present in the carboxy terminus of KCNQ2–5. We tested whether bradykinin modulation of M current in SCG neurons uses CaM. Wt or DN CaM was exogenously expressed in SCG cells using pseudovirions or the biolistic “gene gun.” Using both methods, expression of both wt CaM and DN CaM strongly reduced bradykinin inhibition of M current, but for all groups muscarinic inhibition was unaffected. Cells expressed with wt CaM had strongly reduced tonic current amplitudes as well. We observed similar [Ca2+]i rises by bradykinin in all the groups of cells, indicating that CaM did not affect Ca2+ release from stores. We conclude that M-type currents are highly sensitive to [Ca2+]i and that calmodulin acts as their Ca2+ sensor.
STAM Proteins Bind Ubiquitinated Proteins on the Early Endosome via the VHS Domain and Ubiquitin-interacting Motif
Authors: Mizuno Emi , Kawahata Kensuke , Kato Masaki , Kitamura Naomi , Komada Masayuki
Published: June 2003

Conjugation with ubiquitin acts as a sorting signal for proteins in the endocytic and biosynthetic pathways at the endosome. Signal-transducing adaptor molecule (STAM) proteins, STAM1 and STAM2, are associated with hepatocyte growth factor-regulated substrate (Hrs) but their function remains unknown. Herein, we show that STAM proteins bind ubiquitin and ubiquitinated proteins and that the tandemly located VHS (Vps27/Hrs/STAM) domain and ubiquitin-interacting motif serve as the binding site(s). STAM proteins colocalize with Hrs on the early endosome. Overexpression of STAM proteins, but not their mutants lacking the ubiquitin-binding activity, causes the accumulation of ubiquitinated proteins and ligand-activated epidermal growth factor receptor on the early endosome. These results suggest that through interaction with ubiquitinated cargo proteins on the early endosome via the VHS domain and ubiquitin-interacting motif, STAM proteins participate in the sorting of cargo proteins for trafficking to the lysosome.
Role for Arf3p in Development of Polarity, but Not Endocytosis, inSaccharomyces cerevisiae
Authors: Huang Chun-Fang , Liu Ya-Wen , Tung Luh , Lin Chiou-Hong , Lee Fang-Jen S.
Published: June 2003

ADP-ribosylation factors (ARFs) are ubiquitous regulators of virtually every step of vesicular membrane traffic. Yeast Arf3p, which is most similar to mammalian ARF6, is not essential for cell viability and not required for endoplasmic reticulum-to-Golgi protein transport. Although mammalian ARF6 has been implicated in the regulation of early endocytic transport, we found that Arf3p was not required for fluid-phase, membrane internalization, or mating-type receptor-mediated endocytosis. Arf3p was partially localized to the cell periphery, but was not detected on endocytic structures. The nucleotide-binding, N-terminal region, and N-terminal myristate of Arf3p are important for its proper localization. C-Terminally green fluorescent protein-tagged Arf3, expressed from the endogenous promoter, exhibited a polarized localization to the cell periphery and buds, in a cell cycle-dependent manner. Arf3-GFP achieved its proper localization during polarity growth through an actin-independent pathway. Both haploid and homologous diploid arf3 mutants exhibit a random budding defect, and the overexpression of the GTP-bound form Arf3p(Q71L) or GDP-binding defective Arf3p(T31N) mutant interfered with budding-site selection. We conclude that the GTPase cycle of Arf3p is likely to be important for the function of Arf3p in polarizing growth of the emerging bud and/or an unidentified vesicular trafficking pathway.
A Functional Relationship between NuMA and Kid Is Involved in Both Spindle Organization and Chromosome Alignment in Vertebrate Cells
Authors: Levesque Aime A. , Howard Louisa , Gordon Michael B. , Compton Duane A.
Published: June 2003

We examined spindle morphology and chromosome alignment in vertebrate cells after simultaneous perturbation of the chromokinesin Kid and either NuMA, CENP-E, or HSET. Spindle morphology and chromosome alignment after simultaneous perturbation of Kid and either HSET or CENP-E were no different from when either HSET or CENP-E was perturbed alone. However, short bipolar spindles with organized poles formed after perturbation of both Kid and NuMA in stark contrast to splayed spindle poles observed after perturbation of NuMA alone. Spindles were disorganized if Kid, NuMA, and HSET were perturbed, indicating that HSET is sufficient for spindle organization in the absence of Kid and NuMA function. In addition, chromosomes failed to align efficiently at the spindle equator after simultaneous perturbation of Kid and NuMA despite appropriate kinetochore-microtubule interactions that generated chromosome movement at normal velocities. These data indicate that a functional relationship between the chromokinesin Kid and the spindle pole organizing protein NuMA influences spindle morphology, and we propose that this occurs because NuMA forms functional linkages between kinetochore and nonkinetochore microtubules at spindle poles. In addition, these data show that both Kid and NuMA contribute to chromosome alignment in mammalian cells.
Fission Yeast Cdc23/Mcm10 Functions after Pre-replicative Complex Formation To Promote Cdc45 Chromatin Binding
Authors: Gregan Juraj , Lindner Karola , Brimage Lydia , Franklin Roger , Namdar Mandana , Hart Elizabeth A. , Aves Stephen J. , Kearsey Stephen E.
Published: June 2003

Using a cytological assay to monitor the successive chromatin association of replication proteins leading to replication initiation, we have investigated the function of fission yeast Cdc23/Mcm10 in DNA replication. Inactivation of Cdc23 before replication initiation using tight degron mutations has no effect on Mcm2 chromatin association, and thus pre-replicative complex (pre-RC) formation, although Cdc45 chromatin binding is blocked. Inactivating Cdc23 during an S phase block after Cdc45 has bound causes a small reduction in Cdc45 chromatin binding, and replication does not terminate in the absence of Mcm10 function. These observations show that Cdc23/Mcm10 function is conserved between fission yeast and Xenopus, where in vitro analysis has indicated a similar requirement for Cdc45 binding, but apparently not compared with Saccharomyces cerevisiae, where Mcm10 is needed for Mcm2 chromatin binding. However, unlike the situation in Xenopus, where Mcm10 chromatin binding is dependent on Mcm2–7, we show that the fission yeast protein is bound to chromatin throughout the cell cycle in growing cells, and only displaced from chromatin during quiescence. On return to growth, Cdc23 chromatin binding is rapidly reestablished independently from pre-RC formation, suggesting that chromatin association of Cdc23 provides a link between proliferation and competence to execute DNA replication.
Dislocation of a Type I Membrane Protein Requires Interactions between Membrane-spanning Segments within the Lipid Bilayer
Authors: Lilley Brendan N. , Tortorella Domenico , Ploegh Hidde L.
Published: June 2003

The human cytomegalovirus gene product US11 causes rapid degradation of class I major histocompatibility complex (MHCI) heavy chains by inducing their dislocation from the endoplasmic reticulum (ER) and subsequent degradation by the proteasome. This set of reactions resembles the endogenous cellular quality control pathway that removes misfolded or unassembled proteins from the ER. We show that the transmembrane domain (TMD) of US11 is essential for MHCI heavy chain dislocation, but dispensable for MHCI binding. A Gln residue at position 192 in the US11 TMD is crucial for the ubiquitination and degradation of MHCI heavy chains. Cells that express US11 TMD mutants allow formation of MHCI-β2m complexes, but their rate of egress from the ER is significantly impaired. Further mutagenesis data are consistent with the presence of an alpha-helical structure in the US11 TMD essential for MHCI heavy chain dislocation. The failure of US11 TMD mutants to catalyze dislocation is a unique instance in which a polar residue in the TMD of a type I membrane protein is required for that protein's function. Targeting of MHCI heavy chains for dislocation by US11 thus requires the formation of interhelical hydrogen bonds within the ER membrane.
Breast‐feeding, weaning diet and iron deficiency anaemia in infants
Authors: Mena Alberico Ana Paula , Valeria da Veiga Glória , Ribeiro Baião Mirian , Antonieta de Souza Santos Marta Maria , Buongermino de Souza Sônia , Cornbluth Szarfarc Sophia
Published: June 2003

This study describes the breast‐feeding profile as well as the consumption of iron source foods and vitamin C source foods for both anaemic and non‐anaemic children. A total of 500 infants attending two Municipal Primary Health‐Care Centres in Rio de Janeiro were assessed. The prevalence of anaemia was 57.6 per cent. A low probability of consumption of exclusive breast‐feeding at four months was found (9 per cent for anaemic and 12 per cent for non‐anaemic). Further findings showed that the early consumption of cow’s milk, as well as the low probability of consumption and late introduction of beans, liver and green vegetables in the child’s diet, were considered risk dietary factors for iron deficiency anaemia among the evaluated children.
Napster clones turn their attention to academic e‐books
Authors: Van Hoorebeek Mark
Published: June 2003

This article discusses the effects of “Napster‐like” clone programs on the future of academic e‐books. This review will, first, catalogue the rise and fall of Napster and the development of clone programs that facilitate peer‐to‐peer file sharing; second, examine the main methods by which e‐books are placed on the Web; third, discuss piracy and the subsequent legal issues of intellectual property. Finally, the concept of e‐books in the world of academic publications will be analysed.
LIS education – repackaging infopreneurs or promoting value‐based skills?
Authors: Vaagan Robert W.
Published: June 2003

As the LIS field is being restructured world‐wide, a survey of key institutions and relevant literature confirms that ethics and its information age derivative “infoethics” are becoming important components of LIS research and teaching. LIS scholars and educators need to train students in value‐based skills appropriate for many information age challenges. In Europe LIS research and teaching will in addition need to adapt to the converging forces of the Bologna Agreement’s “European Higher Education Area”.
The effect of the hot air levelling process on skip solder defects in the wave soldering process
Authors: Kiat Choon Teo
Published: June 2003

It was observed that “no solder” or “skipped solder” defects occurred on a particular printed circuit board assembly product during wave soldering. Investigations were carried out to find out the cause of this defect and to recommend an optimal hot air level coating thickness. To evaluate whether thicker plating helps to produce better solderability, new printed circuit boards with an average plating thickness of 4.27 μm were sent for solderability testing. This increase in plating thickness resulted in no defects in the solderability test. This is in contrast to the current printed circuit board that had a no/skipped solder defect rate of 1,433 ppm due to the thinner plating thickness which was in the region of 2.26 μm. In summary, the investigations made have revealed imperfections in the pad plating, and it is recommended that a thicker or more even plating is achieved during the hot air levelling process at the printed circuit board manufacturing site so as to eliminate no/skipped solder defects that are induced by this printed circuit board deficiency.
The Body-Inversion Effect
Authors: Reed Catherine L. , Stone Valerie E. , Bozova Senia , Tanaka James
Published: June 2003

Researchers argue that faces are recognized via the configuration of their parts. An important behavioral finding supporting this claim is the face-inversion effect, in which inversion impairs recognition of faces more than nonface objects. Until recently, faces were the only class of objects producing the inversion effect for untrained individuals. This study investigated whether the inversion effect extends to human body positions, a class of objects whose exemplars are structurally similar to each other. Three experiments compared the recognition of upright and inverted faces, houses, and body positions using a forced-choice, same/different paradigm. For both reaction time and error data, the recognition of possible human body postures was more affected by inversion than the recognition of houses. Further, the recognition of possible human body postures and recognition of faces showed similar effects of inversion. The inversion effect was diminished for impossible body positions that violated the biomechanical constraints of human bodies. These data suggest that human body positions, like faces, may be processed configurally by untrained viewers.
Overactive Action Monitoring in Obsessive-Compulsive Disorder
Authors: Ursu Stefan , Stenger V. Andrew , Shear M. Katherine , Jones Mark R. , Carter Cameron S.
Published: June 2003

The anterior cingulate cortex (ACC) in patients with obsessive-compulsive disorder (OCD) has been found to be hyperactive at rest, during symptom provocation, and after commission of errors in cognitive tasks. This hyperactivity might reflect an abnormality in conflict detection, a hypothesized basic mechanism for the action-monitoring function of the ACC. This hypothesis was tested using functional magnetic resonance imaging, by scanning 11 OCD patients and 13 matched control subjects while they performed a version of the continuous-performance task with four trial types that induced graded levels of response conflict. Although a behavioral index of conflict (i.e., accuracy) was similar for patients and control subjects, the ACC activation was increased in patients during high-conflict trials. The error-related activity in the same brain region was also higher in patients, consistent with previous electrophysiological findings. Both conflict- and error-related activity showed trends for positive correlations with severity of OCD symptoms, but not with anxiety. These findings suggest that as part of an overactive action-monitoring system, the ACC is more directly involved in the pathophysiology of OCD than previously thought.
The Visible Christ and the Invisible Trinity: MT. 5:8 in Augustine's Trinitarian Theology of 400
Authors: Barnes Michel René
Published: June 2003

The essay is an analysis of Augustine's solution to what I identify as the Homoian subordinationist understanding of the Son's visibility. This solution lies in Augustine's (re‐)interpretation of Old Testament theophanies, and his doctrine of the vision through Christ of the Trinity at the end‐time which Augustine supports by an exegesis of Mt. 5:8. Historically, the issue for Augustine is the connection made between doctrines of the Son's inherent "visibility" before the Incarnation and arguments made both against modalism and in support of subordinationism on the basis of that visibility. For Augustine's own Trinitarian theology, any consideration of a sight or vision of God in, e.g., Old Testament theophanies or the Incarnation necessarily raises questions about "sight" as both sensible and noetic knowledge, the structure of our way(s) of knowing, and the role of faith as the means for purifying the knowing capacity in humanity. The question of the vision of God which Augustine addresses in those early books of de Trinitate which are written around the year four hundred is connected to Augustine's epistemological concerns addressed in a variety of writings written before or contemporary to books I‐IV of de Trinitate.
Systemic Hypoxia and the Depression of Synaptic Transmission in Rat Hippocampus after Carotid Artery Occlusion
Authors: Fowler J. C. , Gervitz L. M. , Hamilton M. E. , Walker J. A.
Published: June 2003

The relationship between step reductions in inspired oxygen and the amplitude of evoked field excitatory postsynaptic potentials (fEPSPs) recorded from hippocampal CA1 neurons was examined in anaesthetized rats with a unilateral common carotid artery occlusion. The amplitudes of fEPSPs recorded from the hippocampus ipsilateral to the occlusion were significantly more depressed with hypoxia than were the fEPSPs recorded from the contralateral hippocampus. The adenosine A1‐selective antagonist, 8‐cyclopentyl‐1,3‐dimethylxanthine (8‐CPT), blunted the hypoxic depression of the fEPSP. Tissue partial pressure of oxygen (Ptiss,O2) was measured in the ipsilateral and contralateral hippocampus using glass Clark‐style microelectrodes. Ptiss,O2 fell to similar levels as a function of inspired oxygen in the ipsilateral and contralateral hippocampus, and in the ipsilateral hippocampus after administration of 8‐CPT. Hippocampal blood flow (HBF) was measured using laser Doppler flowmetry. A decline in HBF was associated with systemic hypoxia in both hippocampi. HBF, as a function of inspired oxygen, fell significantly more in the ipsilateral than in the contralateral hippocampus. We conclude that endogenous adenosine acting at the neuronal A1 receptor plays a major role in the depression of synaptic transmission during hypoxic ischaemia. The greater susceptibility of the fEPSP in the ipsilateral hippocampus to systemic hypoxia cannot be explained entirely by differences in Ptiss,O2 or HBF between the two hemispheres.
Clarification
Authors: Hameed M. , Orrell R. W. , Cobbold M. , Goldspink G. , Harridge S. D. R.
Published: June 2003

Journal of Physiology
547, 247–254 (2003)
Dynamics of Multilayered Composite Plates With Shape Memory Alloy Wires
Authors: Zak A. J. , Cartmell M. P. , Ostachowicz W.
Published: June 2003

In this paper certain aspects of the dynamic behavior of a multilayered, composite plate with shape memory alloys (SMA) wires have been investigated. The influence of parameters such as the orientation and location of SMA wires, the orientation and relative volume fraction of reinforcing fibers, the thickness-to-length and length-to-width ratios, and different boundary conditions, on changes in the critical load, the natural frequencies and the modes of vibrations of the plate have all been studied and discussed in the paper. The use of two different techniques, generally known in the literature as the active property tuning and active strain energy tuning methods, has also been investigated. The results presented in this paper have been obtained by the use of the finite element method and a new finite element formulated for multilayered composite plates has been applied for this purpose.