bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of reduced perfusion and reperfusion on C‐fos and HSP‐72 protein immunohistochemistry in gestational day 21 rat brains
Authors: Binienda Zbigniew , Scallet Andrew C.
Published: April 2003

Metabolic stressors such as hyperthermia, seizures and ischemic hypoxia result in the induction of C‐fos and heat‐shock proteins (HSP) in affected brain cells of the adult rodent, especially within the hippocampal region, which normally has high metabolic demands. Here we ligated the uterine vessels of gestational day (GD) 21 rat pups to produce ischemic hypoxia. We confirmed that HSP‐72 protein, as previously reported, was activated in the perinatal rat pup, especially in the hippocampal CA3 region. However, the capability of hippocampal cells to produce C‐fos protein following drug‐induced seizures has been reported to develop only after postnatal day 13. Here, ischemic hypoxia caused CA1 hippocampal cells to produce immunohistochemically detectable C‐fos protein in GD‐21 rats. These results seem to contradict the previous reports of no C‐fos induction in rats this young by demonstrating a functional C‐fos translational mechanism by GD‐21. However, seizure vs ischemic hypoxia‐induced C‐fos expression may involve several different pre‐translational pathways. A delayed development of a receptor, second messenger, or genomic element for regulating C‐fos transcription remain as possible explanations for the late maturity of responsivity to seizures.
The effect of influenza C virus on the Purkinje cells of chick embryo cerebellum
Authors: Parker M. Sharon , O'Callaghan Richard J. , Smith Diane E. , Spence H. Adele
Published: April 2003

Intra‐amniotic inoculation of influenza C virus resulted in observable and quantitatively measurable changes in the Purkinje cells of chick embryo cerebellum. Purkinje cells were visualized by the Golgi‐Cox procedure and prepared for statistical and computer evaluation from camera lucida drawings. Four computer‐generated measurements (the area of the dendritic arbor, the perimeter of the dendritic tree, and the height and width of the cell's arborization) and two manually counted measurements (total number of branches and the number of first order branches) were made. Analysis of Purkinje cells from influenza C virus‐infected embryos showed disturbances in dendritic arborization patterns and misalignment in the arrangement of the cells in the Purkinje cell layer compared to control cells. Statistical evaluation of Purkinje cell arborization showed significant decreases in all measured parameters for the influenza C virus‐infected members when compared with the members of the uninfected control group.
Immunocytochemical detection of serotonin content in raphe neurons of newborn and young adult rabbits before and after acute hypoxia
Authors: Kim Chung S. , McNamara M.Colleen , Lauder Jean M. , Lawson Edward E.
Published: April 2003

The present immunocytochemical study demonstrates serotonin (5‐HT) depletion in the dorsal raphe nucleus (DRN) of 3‐ and 21‐day‐old rabbits following exposure to mild (10% ambient partial pressure of oxygen) and severe hypoxia (5% ambient oxygen). Under the mild hypoxic condition, 5‐HT immunoreactivity in cells and fibers of the DRN was decreased in 3‐day‐old as well as 21‐day‐old rabbits, as indicated by decreased intensity of the staining compared to age‐matched controls. Although this decrease was more pronounced in the younger animals, recovery from mild hypoxia was seen in both age groups. Hypoxic effects were more striking in 3‐day‐old animals under the severe hypoxic condition, indicating a greater depletion of 5‐HT than in the mildly hypoxic condition. However, little additional effect on the older age group was seen. Further, a decreased ability of the 3‐day‐old rabbits to recover following severe hypoxia suggests that protracted effects on the developing serotonergic system occur following severe hypoxia during the neonatal period. This was demonstrated by the long‐lasting decrease in the number of stained cells and fibers of the DRN 4‐hr after return to normal conditions (21% O2). We conclude that newborns have a decreased rate of 5‐HT synthesis and/or metabolic turnover that results in rapid depletion of intracellular stores and protracted time to recover from a hypoxic challenge. Similar effects could occur in human fetuses, newborns or infants following birth trauma, apnea or other events associated with severe hypoxia.
Substance P (SP) and neurokinin a (NKA) in developing submandibular glands of the rat
Authors: Virta E. , Salo A. , Uusitalo H.
Published: April 2003

The effect of isoprenaline, carbachol, substance P (SP) and neurokinin A (NKA) on peroxidase and total protein secretion was studied in the developing postnatal submandibular glands of the rat using in vitro methods. Submandibular glands of 1, 5, 12 and 30 day‐old‐rats were stimulated by 10−5 M isoprenaline and carbachol, and 10−6 M SP and NKA. The stimulatory effects of these compounds were compared to the basic release of peroxidase and total amount of protein from submandibular gland fragments in incubation solution with no added transmitter substances. Indirect immunohistochemical methods were used to study these developing glands from SP‐ and NKA‐immunoreactive (IR) nerve fibers. The distributions of SP‐IR and NKA‐IR nerve fibers closely resembled each other, being most abundantly spread around the developing acini and ducts. The number of these fibers was high on the 1st, 5th and 12th days, but was decreased on the 30th day. On peroxidase release, isoprenaline was the most effective, causing a maximal response of 47 times the basic release on the first postnatal day, after which it gradually decreased. The effects of carbachol, SP and NKA on peroxidase release were clearly weaker and, unlike isoprenaline, their strongest response was on the 5th postnatal day (carbachol, 4.3; SP 5.2; NKA, 4.5). The total protein secretion effect patterns of the studied substances resembled each other more, showing their strongest response on the 5th day (isoprenaline, 5.0; carbachol, 4.5; SP, 4.2; NKA, 3.4) and decreasing thereafter.

In general, both the stimulatory pattern of SP and NKA, and the appearance and distribution of SP‐IR and NKA‐IR nerve fibers during the early postnatal period of development closely resemble those of parasympathetic nerves and their transmitters. Furthermore, it is concluded that the abundancy of SP‐IR and NKA‐IR nerves in the developing submandibular gland is accompanied by the increased sensitivity of the secretory elements to these tachykinins, indicating that they play a role in the maturation of the glandular secretory functions.
Neural cell adhesion molecule and D3 protein in the cerebellum of weaver mutant mice
Authors: Jørgensen Ole Steen
Published: April 2003

Weaver (wv/wv) mutant mice are characterized by extensive granule cell degeneration and can therefore be used as a model for brain degeneration that does not involve blood‐brain barrier damage. The ontogeny of the neural cell adhesion molecule (NCAM) and the neuronal antigen D3 protein were investigated in cerebellum and forebrain of weaver mutant mice up to post‐natal day 60. In the forebrain the concentration of both proteins was virtually unchanged. In cerebellum, in contrast, the concentration of D3 decreased markedly whereas that of NCAM remained unchanged. Similar findings were obtained at post‐natal day 30 in the cerebellum of other neurologic mutants, namely the staggerer (sg/sg) and reeler (rl/rl). At this age the concentration of a synaptic vesicle marker, synaptophysin. was severely decreased in the cerebellum of all three mutants. The concentration of neuron‐specific enolase was less affected, whereas the concentrations of the glial markers glutamine synthetase and glial fibrillary acidic protein were both increased. The NCAM/D3 concentration ratio, which probably reflects the ongoing rate of synaptic remodelling, was increased during the whole ontogeny of weaver mutant mice as compared with heterozygous controls. At post‐natal day 30, the ratio was increased by 180% in weaver, by 170% in staggerer and by 60% in reeler cerebellum. These findings lend further support to the usefulness of the NCAM/D3 ratio as a marker of neural plasticity and synaptic remodelling in both animals and man.
Impaired antigen presentation to CD4+ T‐cells by HIV‐infected monocytes is related to down‐modulation of CD4 expression on helper T‐cells: Possible involvement of HIV‐induced cellular factors
Authors: Louie Audrey T. , Wahl Larry M. , Hewlett Indira K. , Epstein Jay S. , Dhawan Subhash
Published: April 2003

Defective antigen presentation by HIV‐infected monocytes is related to severe immune dysfunction in patients with AIDS, although the mechanism by which this process occurs is not well defined. Here we report that reduced capacity by HIV‐infected monocytes to stimulate or present antigen to CD4+ T‐cells was mediated by cellular factors associated with the plasma membranes of HIV‐infected monocytes. In contrast, soluble factors secreted by HIV‐infected monocytes had little or no effect on T‐cell stimulation. Reduced T‐cell stimulation by HIV‐infected monocytes was related to down‐modulation of CD4 expression on helper T‐cells and was not affected by the inclusion of anti‐HIV‐gp120 Ab, indicating the involvement of soluble or cell‐associated viral envelope protein to be less likely. Exposure of CD4+ T‐cells, that had been in co‐culture with HIV‐infected monocytes, to uninfected monocytes partially restored impaired T‐cell stimulation. Thus, for the first time we report that altered capacity of HIV‐infected monocytes to stimulate and present antigen to CD4+ T‐cells is related to down‐modulation of CD4 expression on T‐cells, and appears to occur via membrane‐associated cellular factors on HIV‐infected monocytes.
Core promoter elements are essential as selective determinants for function of the yeast transcription factor GAL11
Authors: Sakurai Hiroshi , Ohishi Tomoko , Fukasawa Toshio
Published: April 2003

The GAL11 gene product, which copurifies with RNA polymerase II holoenzyme, is necessary for full expression of many, but not all, genes in yeast. Here we shows that the GAL11 dependence of a gene for expression is determined by the core promoter structure. In the GAL80 gene, a gal11 null mutation caused reduction of TATA‐dependent transcription, but exerted no effect on initiator‐mediated transcription. GAL11 stimulated TATA‐dependent transcription, but did not affect the TATA‐independent transcription in HIS4. GAL11 was also required for transcription mediated by a canonical TATA sequence but not by a nonconsensus TATA sequence of HIS3. These results suggest that GAL11 is specifically involved in the transcription machinery formed on the TATA element.
Pre-steady-state kinetics of Bacillus licheniformis 1,3-1,4-beta-glucanase: evidence for a regulatory binding site
Authors: ABEL Mireia , IVERSEN Karin , PLANAS Antoni , CHRISTENSEN Ulla
Published: April 2003

In a previous paper, we reported the first stopped-flow experiments on a Bacillus licheniformis 1,3-1,4-β-glucanase [Abel, Planas and Christensen (2001) Biochem. J. 357, 195–202]. It was shown that the pre-steady-state kinetics of the 1,3-1,4-β-glucanase using the substrate 4-methylumbelliferyl 3-O-β-cellobiosyl-β-d-glucoside may be explained by a reaction scheme involving an induced fit and the binding of two substrates as well as a second enzymic conformational change, whereas the results definitely could not be explained in terms of the simple double-displacement scheme. In the present study, we report further stopped-flow kinetic results on the glucanase using a series of low-molecular-mass substrates with various leaving groups and varying chain length. The analysis of the resulting data leads to the conclusion that the free enzyme exists in two conformations, one of which binds the substrates rather strongly in a regulatory site, before any productive interactions can take place. This corresponds to an allosteric activation mechanism. With these substrates, however, the productive enzyme–substrate species are also able to change into less active or inactive forms. This may be seen as a feedback inhibitory mechanism.
Role of organic anion-transporting polypeptides, OATP-A, OATP-C and OATP-8, in the human placenta-maternal liver tandem excretory pathway for foetal bilirubin
Authors: BRIZ Oscar , SERRANO Maria A. , MACIAS Rocio I. R. , GONZALEZ-GALLEGO Javier , MARIN Jose J. G.
Published: April 2003

Recent functional studies have suggested that, in addition to simple diffusion, carrier-mediated transport may play an important role in foetal unconjugated bilirubin (UCB) uptake by the placenta. We have investigated the role of organic anion-transporting polypeptides (OATPs) in UCB transport by the placenta–maternal liver tandem. RNA was obtained from human liver (hL), human placenta (hPl) at term, and purified (> 80%) cytokeratin-7-positive mononucleated human trophoblast cells (hTCs). By analytical reverse transcription (RT)-PCR, agarose gel electrophoresis separation and sequencing, the mRNA of OATP-A (SLC21A3) and OATP-8 (SLC21A8) was identified in hL, hPl and hTCs, whereas that of OATP-C (SLC21A6) was detectable only in hL. Real-time quantitative RT-PCR revealed that in hL the abundance of mRNA was OATP-8 > OATP-C ≫ OATP-A, whereas in hPl and hTCs this was OATP-8 ≫ OATP-A ≫ OATP-C. Expression levels for these OATPs were hL ≫ hTCs > hPl. Injection of mRNA of OATP-A, OATP-C or OATP-8 or RNA from hL, hPl or hTCs into Xenopus laevis oocytes conferred on them the ability to take up [3H]17β-d-glucuronosyl oestradiol ([3H]E217βG) and [3H]UCB, although in the case of OATP-A mRNA, the induced uptake of [3H]UCB was very low. Cis-inhibition of [3H]E217βG and [3H]UCB uptake by both unlabelled E217βG and UCB was found in all cases. The affinity and efficiency of [3H]UCB transport was OATP-C > OATP-8. Kinetic parameters for [3H]UCB uptake induced by RNA from hTCs resembled most closely those of OATP-8. In conclusion, our results suggest that OATP-8 may play a major role in the carrier-mediated uptake of foetal UCB by the placental trophoblast, whereas both OATP-8 and OATP-C may substantially contribute to UCB uptake by adult hepatocytes.
Simulations and experiments with space-charge-dominated beams
Authors: Kishek R. A. , Bernal S. , Bohn C. L. , Grote D. , Haber I. , Li H. , O’Shea P. G. , Reiser M. , Walter M.
Published: April 2003

Beams in which space charge forces are stronger than the force from thermal pressure are nonneutral plasmas, since particles interact mostly via the long-range collective potential. An ever-increasing number of applications demand such high-brightness beams. The University of Maryland Electron Ring [P. G. O’Shea et al., Nucl. Instrum Methods Phys. Res. A 464, 646 (2001)], currently under construction, is designed for studying the physics of space-charge-dominated beams. Indirect ways of measuring beam emittance near the UMER source produced conflicting results, which were resolved only when a direct measurement of phase space indicated a hollow velocity distribution. Comparison to self-consistent simulation using the particle-in-cell code WARP [D. P. Grote et al., Fusion Eng. Design 32-33, 193 (1996)] revealed sensitivity to the initial velocity distribution. Since the beam is born with nonuniformities and granularity, dissipation mechanisms and rates are of interest. Simulations found that phase mixing by means of chaotic particle orbits is possible in certain situations, and proceeds much faster than Landau damping. The implications for using beams to model other N-body systems are discussed.
Plasma pressure tensor effects on reconnection: Hybrid and Hall-magnetohydrodynamics simulations
Authors: Yin Lin , Winske Dan
Published: April 2003

Collisionless reconnection is studied using two-dimensional (2-D) hybrid (particle ions, massless fluid electrons) and Hall-magnetohydrodynamics (Hall-MHD) simulations. Both use the full electron pressure tensor instead of a localized resistivity in Ohm’s law to initiate reconnection; an initial perturbation or boundary driving to the equilibrium is used. The initial configurations include one-dimensional (1-D) and 2-D current sheets both with and without a guide field. Electron dynamics from the two calculations are compared, and overall agreement is found between the calculations in both reconnection rate and global configuration [L. Yin et al., J. Geophys. Res. 106, 10761 (2001)]. It is shown that the electron drifts in the small-transverse-scale fields near the X point cause the electron motion to decouple from the ion motion, and that reconnection occurs due to electron viscous effects contained in the off-diagonal terms of the electron pressure tensor. Comparing the hybrid and Hall-MHD simulations shows that effects of the off-diagonal terms in the ion pressure tensor, i.e., the ion gyro-radius effects, are necessary in order to model correctly the ion out-of-plane motion. It is shown that these effects can be modeled efficiently in a particle Hall-MHD simulation in which particle ions are used in a predictor/corrector manner to implement ion gyro-radius corrections [L. Yin et al., Phys. Plasmas 9, 2575 (2002)]. For modeling reconnection in large systems, a new integrated approach is examined in which Hall-MHD calculations using a full electron pressure tensor model is embedded inside a MHD simulation. The embedded simulation of current sheet thinning and reconnection dynamics in a realistic 2-D magnetotail equilibrium exhibits smooth transitions of plasma and field quantities between the two regions, with small-scale physics represented well in the compressed current sheet and in the near-X-point region.
The unexpected role of the lower hybrid drift instability in magnetic reconnection in three dimensions
Authors: Lapenta Giovanni , Brackbill J. U. , Daughton W. S.
Published: April 2003

The growth of the lower hybrid drift instability (LHDI) in unstable current sheets induces a fluid velocity shear that drives a Kelvin–Helmholtz instability (KHI). The KHI results in kinking of the current sheet, so that any subsequent magnetic reconnection across the current sheet must occur in three dimensions. While this increases the complexity of modeling reconnection, it is of interest for its possible resolution of the stability to tearing of current sheets with a perpendicular magnetic field. Identification of the role of the LHDI in current sheet kinking required advances in simulation technique that allowed simulations at more realistic mass ratio and long time and length scales. Confidence in the results is strongly enhanced by confirmation with a standard plasma simulation using massively parallel computation. The results of this study have obvious relevance not only to magnetic reconnection and substorms in the Earth’s magnetotail, where the LHDI has been observed, but also where thin current sheets occur, such as the solar corona.
Spheromak merging and field reversed configuration formation at the Swarthmore Spheromak Experiment
Authors: Cothran C. D. , Falk A. , Fefferman A. , Landreman M. , Brown M. R. , Schaffer M. J.
Published: April 2003

The initial results of coaxial co- and counter-helicity spheromak merging studies at the Swarthmore Spheromak Experiment (SSX) [M. R. Brown, Phys. Plasmas 6, 1717 (1999)] are reported. In its new configuration, SSX is optimized to study field reversed configuration (FRC) formation and stability by counter-helicity spheromak merging. A pair of midplane coils magnetically restricts the merging process to determine how the stability of the resulting magnetic configuration depends upon the quantity of toroidal flux remaining from the initial spheromaks. The diagnostic set at SSX, featuring the capability of measuring up to 600 magnetic field components at 800 ns time resolution, permits detailed studies of the dynamic three-dimensional magnetic structures produced during these experiments. A compact array of magnetic probes examines the local reconnection process, while a distributed array of probes examines global magnetic structure. Counter-helicity merging produces a FRC that persists for several Alfvén times, although the oppositely directed toroidal field of the initial spheromaks does not completely annihilate. The m=1 (toroidal) mode dominates late in the evolution, and is consistent with the tilt instability. Co-helicity merging produces a single elongated spheromak that rapidly tilts.
Exact computation of the mean velocity, molecular diffusivity, and dispersivity of a particle moving on a periodic lattice
Authors: Dorfman Kevin D.
Published: April 2003

A straightforward analytical scheme is proposed for computing the long-time, asymptotic mean velocity and dispersivity (effective diffusivity) of a particle undergoing a discrete biased random walk on a periodic lattice among an array of immobile, impenetrable obstacles. The results of this Taylor–Aris dispersion-based theory are exact, at least in an asymptotic sense, and furnish an analytical alternative to conventional numerical lattice Monte Carlo simulation techniques. Results obtained for an obstacle-free lattice are employed to establish generic relationships between the transition probabilities, lattice size, and jump time. As an example, the dispersivity is computed for a solute moving through an isotropic array of obstacles under the influence of a finite external field. The calculation scheme is also shown to agree with existing zero-field results, the latter obtained elsewhere either by first-passage time analysis or use of the Nernst–Einstein equation in the zero-field limit. The generality of this scheme permits the study of more complex lattice structures, in particular trapping geometries.
Charging of dust grains in a plasma with negative ions
Authors: Mamun A. A. , Shukla P. K.
Published: April 2003

The role of negative ions on the charging of dust grains in a plasma is examined. Two models for negative ion distributions are considered. These are streaming negative ions and Boltzmannian negative ions. It is found that the effects of the negative ion number density, negative ion charge, and negative ion streaming speed significantly affect the dust grain surface potential or the dust grain charge.
Simple modes of thin oblate non-neutral plasmas
Authors: Amiranashvili Sh. , Yu M. Y. , Stenflo L.
Published: April 2003

Lagrangian variables are used to describe linear and nonlinear oscillations of a magnetized non-neutral plasma slab in a harmonic trap, for slab width larger or comparable to the Debye length. The plasma particles move along the magnetic field lines, so that the oscillations are one-dimensional. The oscillation spectrum is found analytically, and the thermal corrections to the frequencies are calculated in a nonperturbative manner. Simple exact nonlinear solutions for the low-order modes are also obtained.
Dielectric properties of Pb(Zr20Ti80)O3/Pb(Zr80Ti20)O3 multilayered thin films prepared by rf magnetron sputtering
Authors: Wang Can , Fang Q. F. , Zhu Z. G. , Jiang A. Q. , Wang S. Y. , Cheng B. L. , Chen Z. H.
Published: April 2003

A series of Pb(Zr,Ti)O3 (PZT) films with tetragonal/rhombohedral multilayered structures has been grown on Pt/TiO2/SiO2/Si substrates by rf magnetron sputtering at a relative low temperature. All the films comprise 12 periodicities of Pb(Zr20Ti80)O3/Pb(Zr80Ti20)O3 in constant thickness of 40 nm, but the layer thicknesses of tetragonal phase (dT) and rhombohedral phase (dR) in one periodicity are varied. The electric properties of the films are investigated as a function of dT/dR from 10/30 to 35/5. An enhanced dielectric property is observed in the multilayered films. Especially, a optimal value of dT/dR=30/10 is obtained, where the dielectric constant reaches maximum value of 469 at 100 kHz with a loss tangent of 0.037, and the dielectric constant is about five times that of the single tetragonal phase PZT film formed under the identical condition. Moreover, the polarization also increases in the multilayered films, and remarkably, the film of 30/10 exhibits larger remanent polarization, lower coercive voltage, and more symmetric hysteresis than the other films. The enhancement of dielectric properties is attributed to the presence of interfaces between the tetragonal and the rhombohedral phase layer. This study suggests that the design of the multilayered PZT film capacitor with tetragonal and rhombohedral phase should be an effective way to enhance the dielectric and ferroelectric performance in devices.
Excellent ultrasonic absorption ability of carbon-nanotube-reinforced bulk metallic glass composites
Authors: Bian Zan , Wang Ru Ju , Zhao De Qian , Pan Ming Xiang , Wang Zhi Xin , Wang Wei Hua
Published: April 2003

Zr 52.5 Cu 17.9 Ni 14.6 Al 10 Ti 5 bulk metallic glass composites (BMGCs) containing carbon nanotubes (CNTs) are found to have a strong ultrasonic wave absorption ability. Ultrasonic attenuation coefficients of Zr-based BMGCs increase dramatically with increasing volume fraction of CNTs. The excellent ultrasonic wave absorption ability is attributed mainly to the multiscattering caused by the CNTs and ZrC phase dispersing randomly in the glass matrix.
Utilization of bottleneck resources for profitability through a synchronized operation of marketing and manufacturing
Authors: Sivasubramanian R. , Selladurai V. , Gunasekaran A.
Published: April 2003

Focuses on the synchronous manufacturing system (SMS), a manufacturing management methodology that introduces various operational measures that help increase the performance of the system for optimum production quantity. Enlightens the effects of bottleneck resources and capacity constraints and suggests remedies for synchronized flow in the shop floor. Also recommends methods for production control in synchronous manufacturing, brings together the concepts and elements of marketing and manufacturing along with production quantity. Gives information about several factors that should be taken into consideration while applying synchronous manufacturing methodology in marketing and manufacturing. Shows the results, conclusion and future scope.
Flexible distributed control of production line with the LON fieldbus technology: a laboratory study
Authors: Mahalik N.P. , Lee S.K.
Published: April 2003

Almost all industrial systems are distributed with multiple control points which interact to a limited extent, for which the idea of distribution of task at local (field) level is emerging. As locally‐based application tasks can reduce control delays, a fieldbus‐based smart and reliable DCS solution is recognised as a leader for real‐time industrial automation. Advanced control system has turned itself towards the implementation of digital distributed control systems (DCS) from centralised control systems. The phenomenon is becoming very popular because of its advantages over the whole operating system. Presents a case study for realising manufacturing systems (production lines) with fieldbus technology. The local operating network (LON) fieldbus system was chosen for this purpose because of availability of a wide range of products. Emphasises the reliability aspects of the control systems. A representative of a conveyor system, integrated with field devices, was conceived as the target platform.
Privacy management – a new era in the Australian business environment
Authors: Moghe Vidya
Published: April 2003

People all over the world are increasingly concerned about the privacy issues surrounding the personal information collected by the governments, private organizations and employers. Privacy relates to issues surrounding collection, secure transmission, storage, authorized access, usage and disclosure of personal information. Australian businesses for the first time will need to comply with the new privacy law coming into effect on 21 December 2001. This paper briefly discusses the privacy and related management issues in the information age in general, and privacy related legal requirements in Australia in particular. It further discusses IT‐centric measures that need to be undertaken for the purposes of compliance of the Act and provides an overview of enabling technology currently available.
A neural‐network based method for prediction of γ‐turns in proteins from multiple sequence alignment
Authors: Kaur Harpreet , Raghava G.P.S.
Published: April 2003

In the present study, an attempt has been made to develop a method for predicting γ‐turns in proteins. First, we have implemented the commonly used statistical and machine‐learning techniques in the field of protein structure prediction, for the prediction of γ‐turns. All the methods have been trained and tested on a set of 320 nonhomologous protein chains by a fivefold cross‐validation technique. It has been observed that the performance of all methods is very poor, having a Matthew's Correlation Coefficient (MCC) ≤ 0.06. Second, predicted secondary structure obtained from PSIPRED is used in γ‐turn prediction. It has been found that machine‐learning methods outperform statistical methods and achieve an MCC of 0.11 when secondary structure information is used. The performance of γ‐turn prediction is further improved when multiple sequence alignment is used as the input instead of a single sequence. Based on this study, we have developed a method, GammaPred, for γ‐turn prediction (MCC = 0.17). The GammaPred is a neural‐network‐based method, which predicts γ‐turns in two steps. In the first step, a sequence‐to‐structure network is used to predict the γ‐turns from multiple alignment of protein sequence. In the second step, it uses a structure‐to‐structure network in which input consists of predicted γ‐turns obtained from the first step and predicted secondary structure obtained from PSIPRED. (A Web server based on GammaPred is available at http://www.imtech.res.in/raghava/gammapred/.)
Heat Transfer in Turbulent Boundary Layers Subjected to Free-Stream Turbulence—Part I: Experimental Results
Authors: Barrett Michael J. , Hollingsworth D. Keith
Published: April 2003

Turbulent boundary layers were subjected to grid-generated free-stream turbulence to study the effects of length scale and intensity on heat transfer. Relative to conventional boundary layer thickness measures, test conditions included very small-scale free-stream turbulence. The boundary layers studied ranged from 400–2700 in momentum-thickness Reynolds number and from 450–1900 in enthalpy-thickness Reynolds number. Free-stream turbulence intensities varied from 0.1–8.0%. Ratios of free-stream length scale to boundary-layer momentum thickness ranged from 4.4–32.5. The turbulent-to-viscous length-scale ratios presented are the smallest found in the heat-transfer literature; the ratios spanned from 115–1020. The turbulent-to-thermal ratios (using enthalpy thickness as the thermal scale) are also the smallest reported; the ratios ranged from 3.2–12.3. Relative to clean-free-stream expectations based on the momentum- and enthalpy-thickness Reynolds numbers, the skin friction coefficient increased by up to 16%, and the Stanton number increased by up to 46%.
Computation of Flow Between Two Disks Rotating at Different Speeds
Authors: Kilic Muhsin , Owen J. Michael
Published: April 2003

Disks rotating at different speeds are found in the internal cooling-air systems of most gas turbines. Defining Γ as the ratio of the rotational speed of the slower disk to that of the faster one then Γ=−1, 0 and +1 represents the three important cases of contra-rotating disks, rotor-stator systems and co-rotating disks, respectively. A finite-volume, axisymmetric, elliptic, multigrid solver, employing a low-Reynolds-number k-ε turbulence model, is used for the fluid-dynamics computations in these systems. The complete Γ region, −1⩽Γ⩽+1, is considered for rotational Reynolds numbers of up to Reϕ=1.25×106, and the effect of a radial outflow of cooling air is also included for nondimensional flow rates of up to Cw=9720. As Γ→−1, Stewartson-flow occurs with radial outflow in boundary layers on both disks and between which is a core of nonrotating fluid. For Γ≈0, Batchelor-flow occurs, with radial outflow in the boundary layer on the faster disk, inflow on the slower one, and between which is a core of rotating fluid. As Γ→+1, Ekman-layer flow dominates with nonentraining boundary layers on both disks and a rotating core between. Where available, measured velocity distributions are in good agreement with the computed values.
ANOMALOUS HIGGS COUPLINGS
Authors: GONZALEZ-GARCIA M. C.
Published: April 2003

We review the effects of new effective interactions on Higgs-boson phenomenology. New physics in the electroweak bosonic sector is expected to induce additional interactions between the Higgs doublet field and the electroweak gauge bosons, leading to anomalous Higgs couplings as well as anomalous gauge-boson self-interactions. Using a linearly realized SU (2)L× U (1)Y invariant effective Lagrangian to describe the bosonic sector of the Standard Model, we review the effects of the new effective interactions on the Higgs-boson production rates and decay modes. We summarize the results from searches for the new Higgs signatures induced by the anomalous interactions in order to constrain the scale of new physics, in particular at CERN LEP and Fermilab Tevatron colliders.
USING DYNAMIC NEURAL NETWORKS TO GENERATE CHAOS: AN INVERSE OPTIMAL CONTROL APPROACH
Authors: SANCHEZ EDGAR N. , PEREZ JOSE P. , CHEN GUANRONG
Published: April 2003

This Letter suggests a new approach to generating chaos via dynamic neural networks. This approach is based on a recently introduced methodology of inverse optimal control for nonlinear systems. Both Chen's chaotic system and Chua's circuit are used as examples for demonstration. The control law is derived to force a dynamic neural network to reproduce the intended chaotic attractors. Computer simulations are included for illustration and verification.
AN EXPERIMENTAL STUDY ON DELAYED-FEEDBACK CONTROL OF ONE-WAY THREE-COUPLED CHAOTIC MAPS
Authors: KONISHI KEIJI , OYAMA HIDEKAZU , KOKAME HIDEKI , HIRATA KENTARO
Published: April 2003

This paper experimentally verifies that one-way three-coupled chaotic maps implemented by electronic circuits can be stabilized by a decentralized delayed-feedback control. The main part of each map site is a chaos IC chip (NJH1101) which includes a piecewise nonlinear map, delay devices and clock generator. The delayed-feedback controller is also implemented by electronic devices. Our control experiments succeed in stabilizing a fixed point of the coupled maps.
STATISTICAL SIMULATIONS OF THE LOW-FREQUENCY NOISE IN POLYSILICON EMITTER BIPOLAR TRANSISTORS USING A MODEL BASED ON GENERATION-RECOMBINATION CENTERS
Authors: SANDÉN MARTIN , ÖSTLING MIKAEL , MARINOV OGNIAN , DEEN M. JAMAL
Published: April 2003

In this work, a new, physically based model for the low-frequency noise is investigated by statistical simulations. The proposed model is based only on superposition of generation-recombination centers, and can predict the frequency-, current- and area-dependence of the low-frequency noise, as well as the area-dependence of the variation in the noise level. Measurements on Bipolar Junction Transistors (BJTs) are found to be in excellent agreement with the simulated results. For devices with large emitter areas AE, the model predicts a spectral density SIn ~ 1/f. For devices with submicron AE, SIn strongly deviates from a 1/f behavior, and several generation-recombination centers dominate the spectrum. However, the average spectrum , calculated from several BJTs with identical AE, has a frequency dependence ~ 1/f. The extracted areal trap density within the frequency range 1-104 Hz is nT = 3 × 109 cm -2. The simulations show that the condition for observing g-r noise in the spectrum, strongly depends on the number of traps NT, as well as the distribution of the corresponding energy level for the traps. The relative noise level is found to vary in a non-symmetrical way around < SIn>, especially for small AE. For AE < 0.1 μ m 2, the model predicts a relative variation in the noise level [Formula: see text] below , and [Formula: see text] above . For AE > 0.3 μ m 2, the variation is found to be [Formula: see text].
MULTIFRACTAL ANALYSIS OF 1/f FLUCTUATIONS IN SIMULATED EXTENSIVE AIR SHOWERS PRODUCED BY DIFFERENT PRIMARY COSMIC RAY
Authors: FALEIRO E. , GÓMEZ J. M. G.
Published: April 2003

As was pointed out in some recent papers, the fluctuations in the secondary particle distribution of extensive air showers at observation level exhibit a complex structure which can be interpreted as a white noise plus a 1/f noise. The resulting coloured noise fits very well into the framework of the universal multitractal theory. In this paper we compare the e+ and e- density fluctuations generated by different primary cosmic rays, namely, high energy γ rays, protons, and helium, oxygen and iron nuclei, and the universal multifractal parameters for all these primaries are calculated for several samples. The performed analysis reveals that the Levy index and the mean codimension depend monotonically on the mass of the primary cosmic ray. Some future applications of the multifractal properties of extensive air showers are suggested.
The influence of a forest canopy on top‐down and bottom‐up diffusion in the planetary boundary layer
Authors: Patton E. G. , Sullivan P. P. , Davis K. J.
Published: April 2003

Results from two nested‐grid large‐eddy simulations comparing cases with and without a plant canopy are presented. Through comparisons of numerically generated mean and turbulence statistics, the influence of a plant canopy with a leaf area index of two is shown to modify the air flow compared with an identical case without plants. Investigations of instantaneous fields and spatial spectra show that a plant canopy alters the spatial structure of turbulence and acts to shift the dominant scale to a scale on the order of the canopy height. Distributed drag and scalar sources, representing the presence of a scalar emitting deciduous forest, have little influence on top‐down diffusion, but enhanced mixing and increased turbulence intensities result in a dramatic modification to bottom‐up scalar diffusion up to ∼4.5 times the height of the canopy. Use of previously proposed bottom‐up gradient function with observations of scalar gradients under unstable stability conditions at 50 m over a 25 m tall forest (leaf area index of two) are shown to lead to an underestimate of the scalar emission flux by a factor of four. New top‐down and bottom‐up functions are proposed to include these canopy‐induced effects for this particular canopy. Copyright © 2003 Royal Meteorological Society
The characteristics of wind and wave fields modelled with different resolutions
Authors: Cavaleri Luigi , Bertotti Luciana
Published: April 2003

A number of meteorological situations are studied using the operational models at the European Centre for Medium‐Range Weather Forecasts, and a series of short‐term forecast experiments is made for four different resolutions of the meteorological model. A comparison with the measurements and between the corresponding results allows an evaluation of the relative benefits of increased resolution. The focus is on the surface wind speeds and on the wave heights.

Good quality results are found over the oceans, especially in areas with strong spatial gradients. Consistent with the already good quality of the present operational results, the improvements with increased resolution are small, but significant. In enclosed basins, as in the case of the Mediterranean Sea, it is found that both the surface wind speed and wave height are strongly underestimated. The improvements with increased resolution are greater than over the oceans, but still not sufficient to give agreement with measured data. Copyright © 2003 Royal Meteorological Society
Kinetic compensation effect in thermal decomposition of cellulosic materials in air atmosphere
Authors: Liu Naian , Zong Rowen , Shu Lifu , Zhou Jianjun , Fan Weicheng
Published: April 2003

The decomposition of wood and leaf of eight species in air atmosphere is examined by nonisothermal means with linear temperature programming, and a simple kinetic description is developed based on the experimental results and integral analysis method. The relation between the apparent activation energy E and preexponential factor A is analyzed, and it is found that the parameters E and A resulted from the variation of the species and the variation of model functions exhibit kinetic compensation effects. Quantitative and statistical criterion to distinguish between real and false compensation effects is discussed in detail. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 135–141, 2003
Hydrogenation of cis‐1,4‐poly(isoprene) catalyzed by OsHCl(CO)(O2)(PCy3)2
Authors: Charmondusit Kitikorn , Prasassarakich Pattarapan , McManus Neil T. , Rempel Garry L.
Published: April 2003

The quantitative hydrogenation of cis‐1,4‐poly(isoprene) (CPIP) provides an easy entry to the alternating copolymer of ethylene–propylene, which is difficult to prepare by conventional polymerization. The homogeneous hydrogenation of CPIP, in the presence of OsHCl(CO)(O2)(PCy3)2 as catalyst, has been studied by monitoring the amount of hydrogen consumed during the reaction. The final degree of olefin conversion measured by computer‐controlled gas uptake apparatus was confirmed by infrared spectroscopy and 1H nuclear magnetic resonance analysis. Kinetic experiments for CPIP hydrogenation in toluene solvent indicate that the hydrogenation rate is first order with respect to catalyst and carbon–carbon double bond concentration. A second‐order dependence on hydrogen concentration for low values and a zero‐order dependence for higher values of the hydrogen concentration was observed. The apparent activation energy for the hydrogenation of CPIP over the temperature range of 115–140°C was 109.3 kJ/mole. Mechanistic aspects of this catalytic process are discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 142–152, 2003
Emerging use of gene expression microarrays in plant physiology
Authors: Wullschleger Stan D. , Difazio Stephen P.
Published: April 2003

Microarrays have become an important technology for the global analysis of gene expression in humans, animals, plants, and microbes. Implemented in the context of a well‐designed experiment, cDNA and oligonucleotide arrays can provide high‐throughput, simultaneous analysis of transcript abundance for hundreds, if not thousands, of genes. However, despite widespread acceptance, the use of microarrays as a tool to better understand processes of interest to the plant physiologist is still being explored. To help illustrate current uses of microarrays in the plant sciences, several case studies that we believe demonstrate the emerging application of gene expression arrays in plant physiology were selected from among the many posters and presentations at the 2003 Plant and Animal Genome XI Conference. Based on this survey, microarrays are being used to assess gene expression in plants exposed to the experimental manipulation of air temperature, soil water content and aluminium concentration in the root zone. Analysis often includes characterizing transcript profiles for multiple post‐treatment sampling periods and categorizing genes with common patterns of response using hierarchical clustering techniques. In addition, microarrays are also providing insights into developmental changes in gene expression associated with fibre and root elongation in cotton and maize, respectively. Technical and analytical limitations of microarrays are discussed and projects attempting to advance areas of microarray design and data analysis are highlighted. Finally, although much work remains, we conclude that microarrays are a valuable tool for the plant physiologist interested in the characterization and identification of individual genes and gene families with potential application in the fields of agriculture, horticulture and forestry. Copyright © 2003 John Wiley & Sons, Ltd.
Progress in establishing common standards for exchanging proteomics data
Authors: Orchard Sandra , Kersey Paul , Zhu Weimin , Montecchi‐Palazzi Luisa , Hermjakob Henning , Apweiler Rolf
Published: April 2003

The Proteomics Standards Initiative (PSI) aims to define community standards for data representation in proteomics and to facilitate data comparison, exchange and verification. Rapid progress has been made in the development of common standards for data exchange in the fields of both mass spectrometry and protein–protein interactions since the first PSI meeting . Both hardware and software manufacturers have agreed to work to ensure that a proteomics‐specific extension is created for the emerging ASTM mass spectrometry standard and the data model for a proteomics experiment has advanced significantly. The Protein–Protein Interactions (PPI) group expects to publish the Level 1 PSI data exchange format for protein–protein interactions by early summer this year, and discussion as to the additional content of Level 2 has been initiated. Copyright © 2003 John Wiley & Sons, Ltd.
Meningioma with extensive noncalcifying collagenous whorls and glial fibrillary acidic protein expression: New variant of meningioma diagnosed by smear preparation
Authors: Pope Leonora Z.B. , Tatsui Claudio E. , Moro Marlus S. , Neto Arnolfo C. , Bleggi‐Torres Luiz F.
Published: April 2003

The purpose of this report is to describe the unique cytological findings of a new recently characterized type of meningioma that has extensive noncalcifying collagenous whorls and glial fibrillary acid protein (GFAP) expression. This new entity, described by Haberler and colleagues, was named whorling sclerosing variant of meningioma. The patient was a 34‐yr‐old white man with a large tumor in the brainstem. Intraoperative smear preparations showed a tumor with a large number of solid hyaline masses in a loose background and in focal areas tumor cells formed cohesive nests with a somewhat whorling appearance. The histological sections showed a neoplasia composed of innumerable eosinophilic, collagenous, noncalcified round deposits, cuffed by scattered meningothelial tumor cells. The neoplastic cells showed diffuse cytoplasmic reactivity for EMA and vimentin, as well as positivity to GFAP. This is the first cytological description of this new entity in the literature. Diagn. Cytopathol. 2003;28:274–277. © 2003 Wiley‐Liss, Inc.