bluuebunny/crossref_metadata_2025 huggingface dataset:
PULSED PHOTOACOUSTIC DETERMINATION OF ABSOLUTE FLUORESCENT QUANTUM YIELD OF THE LASER DYE RHODAMINE B
Authors: BINDHU C.V. , HARILAL S.S. , ISSAC RIJU C. , NAMPOORI V.P.N. , VALLABHAN C.P.G.
Published: October 2004

Pulsed photoacoustic technique which is found to be a very convenient and accurate method, is used for the determination of absolute fluorescence quantum yield of laser dye rhodamine B. Concentration and power dependence of quantum yield of rhodamine B in methanol for excitation at 532 nm is reported here. Results show that a rapid decrease in quantum yield as the concentration is increased and finally it reaches the limit corresponding to fluorescence quenching.
MICROSTRUCTURAL AND MECHANICAL PROPERTY CHARACTERISTICS OF BINARY Ni-Ge ALLOYS
Authors: JIN Y. , CHATURVEDI M.C.
Published: October 2004

Polycrystalline Ni 3 Ge intermetallic compound displays very poor ductility due to its weak grain boundary cohesion. In addition, its ductility cannot be improved by the boron doping method although this technique has proved quite effective in a similar Ni 3 Al intermetallic compound. Therefore, dual phase method seems to be a reasonable choice for developing advanced Ni–Ge based high temperature materials with a potential for industrial applications. In this communication, the recent progress in the microstructural and mechanical property characterization of binary Ni–Ge alloys has been reviewed. In addition to the rapid precipitation of fine Ni3Ge particles in the Ni solid solution, the spinodal decomposition has been observed to occur in the initial stage of aging at 873 K, while vacancy-induced short range ordered structure was found in the naturally aged alloys. The elastic constants of Ni 3 Ge single crystal at various annealing temperatures have been also determined.
INVESTIGATION ON SYNTHESIS AND CHARACTERIZATION OF Hg1−xTlxBa2Ca2Cu3O8+δ WITH 0.2≤x≤0.8
Authors: PANDEY A.K. , VERMA G.D. , SRIVASTAVA O.N.
Published: October 2004

In the present investigation, Tl substituted Hg bearing cuprate high temperature superconductors corresponding to Hg 1−x Tl x Ba 2 Ca 2 Cu 3 O 8+δ with x=0.2, 0.4, 0.5, 0.6, 0.7 and 0.8, have been synthesized. The as synthesized phases characterized through XRD and TEM have been found to possess Hg:1223 as the dominant structural phase. These superconductors, with increasing Tl concentration have been found to pass from the underdoped through optimally doped to the overdoped regimes. The Tc for the underdoped regime (x=0.2) corresponds to ~117 K, for the overdoped regime (x=0.8), it is ~119 K. An interesting result emanating from the present study relates to the fact that an optimum Tc of ~122 K is obtained through oxygenation (annealing in oxygen) of the underdoped regime, reduction (annealing in Ar+H2) of overdoped regime, or else through optimum hole doping by suitable adjustment of substituted Tl concentration (x=0.6).
SYNTHESIS AND CHARACTERISATION OF Dy2CaCuO5 COMPOUND
Authors: JEYABALAN K. , KALIYAPERUMAL L.K. , SRINIVAS J.
Published: October 2004

We report here the synthesis and characterisation of Dy 2 CaCuO 5 compound. It crystallises in an orthorhombic cell with the lattice parameters a=5.888(6) Å, b=7.211(9) Å and c=12.997(2) Å.
SPINODAL DECOMPOSITION IN HYDROGEN-BONDED POLYMER BLENDS
Authors: HOBBIE E.K. , MERKLE G. , BAUER B.J. , HAN C.C.
Published: October 2004

Time-resolved small-angle neutron-scattering (SANS) studies of spinodal decomposition in hydrogen-bonded blends of polystyrene and poly(butylmethacrylate) reveal extremely slow kinetics of phase separation in the vicinity of the critical point. The experimental data are interpreted within the context of a mean-field model that predicts energetic barriers to extended composition fluctuations. The scenario bears a resemblance to dynamic critical phenomena in Ising systems with coupling to a set of mobile impurities.
SECOND PEAK IN AC LOSSES OF Bi2Sr2Ca1Cu2Ox TAPES
Authors: MIKHEENKO P.N. , IONESCU M. , HORVAT J. , DOU S.X.
Published: October 2004

An additional broad peak in AC losses of Bi 2 Sr 2 Ca 1 Cu 2 O x tapes is observed. Using a new method based on the model of separated finite-size stacks of superconducting layers it is found that this peak reflects the presence of Bi 2 Sr 2 CuO x intergrowth in the sample. Kosterlitz-Thouless transition temperatures of pure Bi 2 Sr 2 Ca 1 Cu 2 O x and intergrowths of different thickness are defined. Our results are confirmed by the direct TEM measurements.
A NONLINEAR MODEL OF THE COLLECTIVE SPONTANEOUS EMISSION BY A SPIN SYSTEM
Authors: MIZRAHI SALOMON S. , DODONOV VICTOR V. , OTERO DINO
Published: October 2004

We propose a nonlinear quantum master equation, which results in the nonlinear Bloch-like equations, similar to those which are used usually to describe the collective spontaneous emission by a system of two-level atoms or a spin system in a magnetic field. On the one hand, the new equation is the unique simplest homogeneous and nonsingular generalization of the linear master equations for quantum systems in the finite-dimensional Hilbert space. On the other hand, it corresponds to the mean-field approximation, and in this form it can be used for a larger class of systems. Our equations describe both triggered and pure spin emission processes (when the population is completely inverted), and their solutions show the occurrence of secondary emission peaks, as observed in experiments.
ACTIVATION ENERGIES IN THE VORTEX LIQUID STATE OF BULK (Bi1.6Pb0.4)(Sr1.8Ba0.2)Ca2Cu3Oy SUPERCONDUCTOR
Authors: POP A. V. , DELTOUR R. , CIURCHEA D. , HĂRĂBOR A. , ILONCA GH. , COLDEA S.
Published: October 2004

Magnetoresistivity measurements as a function of temperature, ρ(B, T) in applied magnetic field B up to 0.7 T have been carried out on a sample of the 110 K phase of the (Bi, Pb)-(Sr, Ba)-Ca-Cu-O system. The dρ/dT versus T curves in an applied magnetic field reveal the intra- and intergranular transitions. The behavior of these transitions as function of the magnetic field is presented. Thermally activated flux motion has been studied. The activation energy is proportional to (1−T/T c ) ln B, and suggests a 2D-state in which the dissipation is dominated by the cutting mechanism in an entangled flux liquid.
MAGNETIC FIELDS IN CLUSTERS OF GALAXIES
Authors: GOVONI FEDERICA , FERETTI LUIGINA
Published: October 2004

The existence of magnetic fields associated with the intracluster medium in clusters of galaxies is now well established through different methods of analysis. Magnetic fields are investigated in the radio band from studies of the rotation measure of polarized radio galaxies and the synchrotron emission of cluster-wide diffuse sources. Other techniques include X-ray studies of the inverse Compton emission and of cold fronts and magneto hydrodynamic simulations. We review the main issues that have led to our knowledge on magnetic fields in clusters of galaxies. Observations show that cluster fields are at the μG level, with values up to tens of μG at the center of cooling core clusters. Estimates obtained from different observational approaches may differ by about an order of magnitude. However, the discrepancy may be alleviated by considering that the magnetic field is not constant throughout the cluster, and shows a complex structure. In particular, the magnetic field intensity declines with the cluster radius with a rough dependence on the thermal gas density. Moreover, cluster magnetic fields are likely to fluctuate over a wide range of spatial scales with values from a few kpc up to hundreds kpc. Important information on the cluster field are obtained by comparing the observational results with the prediction from numerical simulations. The origin of cluster magnetic fields is still debated. They might originate in the early Universe, either before or after the recombination, or they could have been deposited in the intracluster medium by normal galaxies, starburst galaxies, or AGN. In either case, magnetic fields undergo significant amplification during the cluster merger processes.
COSMOLOGICAL PARAMETER ESTIMATION WITH LARGE SCALE STRUCTURE AND SUPERNOVAE DATA
Authors: ODMAN CAROLINA J. , HOBSON MIKE , LASENBY ANTHONY , MELCHIORRI ALESSANDRO
Published: October 2004

Most cosmological parameter estimations are based on the same set of observations and are therefore not independent. Here, we test the consistency of parameter estimations using a combination of large-scale structure and supernovae data, without cosmic microwave background (CMB) data. We combine observations from the IRAS 1.2 Jy and Las Campanas redshift surveys, galaxy peculiar velocities and measurements of type Ia supernovae to obtain [Formula: see text], Ωm=0.28±0.05 and [Formula: see text] in agreement with the constraints from observations of the CMB anisotropies by the WMAP satellite. We also compare results from different subsets of data in order to investigate the effect of priors and residual errors in the data. We find that some parameters are consistently well constrained whereas others are consistently ill-determined, or even yield poorly consistent results, thereby illustrating the importance of priors and data contributions.
RADIATING GRAVITATIONAL COLLAPSE WITH SHEAR VISCOSITY AND BULK VISCOSITY
Authors: NOGUEIRA P. C. , CHAN R.
Published: October 2004

A model of a collapsing radiating star consisting of a fluid with shear viscosity and bulk viscosity undergoing radial heat flow with outgoing radiation is studied. This kind of fluid is the most general viscous fluid we can have. The pressure of the star, at the beginning of the collapse, is isotropic but, due to the presence of the shear viscosity and the bulk viscosity, the pressure becomes more and more anisotropic. The radial and temporal behaviors of the density, pressure, mass, luminosity, the effective adiabatic index and the Kretschmann scalar are analyzed. The collapsing time, density, mass, luminosity and Kretschmann scalar of the star do not depend on the viscosity of the fluid (nor the shear viscosity and neither the bulk viscosity).
ON THE EVOLUTION OF A MASSLESS SCALAR FIELD IN A SCHWARZSCHILD BACKGROUND: A NEW LOOK AT HAWKING RADIATION AND THE INFORMATION PARADOX
Authors: MELNIKOV KIRILL , WEINSTEIN MARVIN
Published: October 2004

We exhibit an explicit foliation of Schwarzschild space–time by spacelike hypersurfaces which extend from Schwarzschild r=0 to r=∞. This allows us to compute the values of a massless scalar field for all space–time points which lie in the future of the surface on which we initially quantize the theory. This is to be contrasted with approaches which start at past null infinity and propagate to future null infinity. One of its virtues is that this method allows us to discuss both asymptotic Hawking radiation and what is happening at finite distances from the black hole.

In order to explain the techniques we use, we begin by discussing variants of the flat-space moving mirror9 problem. Then we discuss the canonical quantization of the massless scalar field theory and the geometric optics approximation which we use to solve the Heisenberg equations of motion in the black hole background. Using the example of an infalling mirror, an analogue of the moving mirror problem, we show that, although our spacelike slices extend to r=0, we can avoid discussing an initial state which extends through the horizon. Furthermore, we show that in the same way we avoid having to deal with the singularity at r=0 when we first quantize the system. This discussion naturally leads to a suggestion of how to handle the question of what is happening when the mirror hits the singularity. In the last section of the paper we discuss a discretization of the computation which behaves in the manner we suggest and yet exhibits Hawking radiation.5 This formulation of the problem allows us to discuss all the issues in an explicitly unitary setting. The resulting picture raises some interesting questions about the information paradox.
RADIATION AND OUTFLOW BOUNDARY CONDITIONS FOR DIRECT COMPUTATION OF ACOUSTIC AND FLOW DISTURBANCES IN A NONUNIFORM MEAN FLOW
Authors: TAM CHRISTOPHER K.W. , DONG ZHONG
Published: October 2004

It is well known that Euler equations support small amplitude acoustic, vorticity and entropy waves. To perform high quality direct numerical simulations of flow generated noise problems, acoustic radiation boundary conditions are required along inflow boundaries. Along boundaries where the mean flow leaves the computation domain, outflow boundary conditions are needed to allow the acoustic, vorticity and entropy disturbances to exit the computation domain without significant reflection. A set of radiation and outflow boundary conditions for problems with nonuniform mean flows are developed in this work. Flow generated acoustic disturbances are usually many orders of magnitude smaller than that of the mean flow. To capture weak acoustic waves by direct computation (without first separating out the mean flow), the intensity of numerical noise generated by the numerical algorithm and the radiation and outflow boundary conditions (and the computer) must be extremely low. It is demonstrated by a test problem involving sound generation by an oscillatory source that weak acoustic waves with maximum velocity fluctuation of the order of 10−9 of the mean flow velocity can be computed accurately using the proposed radiation boundary conditions. The intensity of such acoustic waves is much smaller than the numerical error of the mean flow solution.
HELICOPTER NOISE PREDICTIONS USING KIRCHHOFF METHODS
Authors: STRAWN ROGER C. , BISWAS RUPAK , LYRINTZIS ANASTASIOS S.
Published: October 2004

This paper presents two methods for predicting the noise from helicopter rotors in forward flight. Aerodynamic and acoustic solutions in the near field are computed with a finite-difference solver for the Euler equations. Two different Kirchhoff acoustics methods are then used to propagate the acoustic signals to the far field in a computationally-efficient manner. One of the methods uses a Kirchhoff surface that rotates with the rotor blades. The other uses a nonrotating Kirchhoff surface. Results from both methods are compared to experimental data for both high-speed impulsive noise and blade-vortex interaction noise. Agreement between experimental data and computational results is excellent for both cases. The rotating and nonrotating Kirchhoff methods are also compared for accuracy and efficiency. Both offer high accuracy with reasonable computer resource requirements. The Kirchhoff integrations efficiently extend the near-field finite-difference results to predict the far field helicopter noise.
COMPARISON OF THE EFFECTS OF MEDIUM MOTION AND ITS INHOMOGENEITY ON SOUND PROPAGATION IN THE OCEAN
Authors: GRIGORIEVA NATALIE S.
Published: October 2004

The purpose of this paper is to compare the effects of medium motion and its inhomogeneity on sound propagation in the ocean at frequencies from a few tens to a hundred Hz for the sound paths up to several hundreds kilometers in length. It is considered the acoustic propagation passing through a cyclonic eddy and the Gulf Stream current. In moving fluid, the sound propagation is described by a system of seven linear partial differential equations for seven unknown elements of a sound wave. These are the sound pressure, the particle oscillation velocity in a sound wave as well as the changes in medium density, its entropy and concentration of the salt caused by the passage of a sound wave. All these elements of a sound wave are seek in the form of a sum of the quasi-normal waves using the modification of the method of horizontal rays/vertical modes. The numerical simulations are carried out on the base of formulas taking into account the first correction to the adiabatic approximation.
FUZZY OPTIMIZATION OF REAL FUNCTIONS
Authors: BURGIN MARK
Published: October 2004

The main goal of this paper is to develop such means of analysis that allows us to reflect and model vagueness and uncertainty of our knowledge, which result from imprecision of measurement and inaccuracy of computation. To achieve this goal, we use here neoclassical analysis to problems of optimization. Neoclassical analysis extends the scope and results of the classical mathematical analysis by applying fuzzy concepts to conventional mathematical objects, such as functions, sequences, and derivatives. Basing on the theory of fuzzy limits, we construct a fuzzy extension for the classical theory of differentiation in the context of computational mathematics. It is done in the second part of this paper, going after introduction. Two kinds of fuzzy derivatives of real functions are considered: weak and strong ones. In addition, we introduce and study extended fuzzy derivatives, which may take infinite values. In the third part of this paper, fuzzy derivatives are applied to a study of maxima and minima of real functions. Different conditions for maxima and minima of real functions are obtained. Some of them are the same or at least similar to the conditions for the differentiable functions, while others differ in many aspects from those for the standard differentiable functions. Many classical results are obtained as direct corollaries of propositions for fuzzy derivatives, which are proved in this paper. Such results as the Fuzzy Intermediate Value theorem, Fuzzy Fermat's theorem, Fuzzy Rolle's theorem, and Fuzzy Mean Value theorem are proved. These results provide better theoretical base for computational methods of optimization.
THE INTEGRAL OVER A DIRECTED LINE SEGMENT OF FUZZY MAPPING AND ITS APPLICATIONS
Authors: WANG GUIXIANG , WU CONGXIN
Published: October 2004

In this paper, we present the definition of integral of fuzzy mappings from the fuzzy number space E into E, and discuss its properties and calculation. And as an application of the integral, we provide a method of robustness estimates for the traffic volumes passing a road each day (24 hours). In addition, we also give another example of the integral characterizing the distance travelled in an imprecise or uncertain environment of time and speed.
SPECTRAL ANALYSIS OF GUANINE AND CYTOSINE FLUCTUATIONS OF MOUSE GENOMIC DNA
Authors: LI WENTIAN , HOLSTE DIRK
Published: October 2004

We study global fluctuations of the guanine and cytosine base content (GC%) in mouse genomic DNA using spectral analyses. Power spectra S(f) of GC% fluctuations in all nineteen autosomal and two sex chromosomes are observed to have the universal functional form S(f)~1/fα (α≈1) over several orders of magnitude in the frequency range 10-7<f<10-5 cycle/base, corresponding to long-ranging GC% correlations at distances between 100 kb and 10 Mb. S(f) for higher frequencies (f>10-5 cycle/base) shows a flattened power-law function with α<1 across all twenty-one chromosomes. The substitution of about 38% interspersed repeats does not affect the functional form of S(f), indicating that these are not predominantly responsible for the long-ranged multi-scale GC% fluctuations in mammalian genomes. Several biological implications of the large-scale GC% fluctuation are discussed, including neutral evolutionary history by DNA duplication, chromosomal bands, spatial distribution of transcription units (genes), replication timing, and recombination hot spots.
DISORDER AND FLUCTUATIONS IN NONLINEAR EXCITATIONS IN DNA
Authors: CUENDA SARA , SÁNCHEZ ANGEL
Published: October 2004

We study the effects of the sequence on the propagation of nonlinear excitations in simple models of DNA, and how those effects are modified by noise. Starting from previous results on soliton dynamics on lattices defined by aperiodic potentials [23], we analyze the behavior of lattices built from real DNA sequences obtained from human genome data. We confirm the existence of threshold forces, already found in Fibonacci sequences, and of stop positions highly dependent on the specific sequence. Another relevant conclusion is that the effective potential, a collective coordinate formalism introduced by Salerno and Kivshar [21] is a useful tool to identify key regions that control the behaviour of a larger sequence. We then study how the fluctuations can assist the propagation process by helping the excitations to escape the stop positions. Our conclusions point out to improvements of the model which look promising to describe mechanical denaturation of DNA. Finally, we also consider how randomly distributed energy focus on the chain as a function of the sequence.
RANDOM WALKS, SELF-AVOIDING WALKS AND 1/f NOISE ON FINITE LATTICES
Authors: GRÜNEIS FERDINAND
Published: October 2004

We investigate the probabilities for a return to the origin at step n of a random walker on a finite lattice. As a consistent measure only the first returns to the origin appear to be of relevance; these include paths with self-intersections and self-avoiding polygons. Their return probabilities are power-law distributed giving rise to 1/f b noise. Most striking is the behavior of the self-avoiding polygons exhibiting a slope b=0.83 for d=2 and b=0.93 for d=3 independent on lattice structure.
LANGEVIN APPROACH TO UNDERSTAND THE NOISE OF MICROWAVE TRANSISTORS
Authors: PRINCIPATO FABIO , SPAGNOLO BERNARDO , FERRANTE GAETANO , CADDEMI ALINA
Published: October 2004

A Langevin approach to understand the noise of microwave devices is presented. The device is represented by its equivalent circuit with the internal noise sources included as stochastic processes. From the circuit network analysis, a stochastic integral equation for the output voltage is derived and from its power spectrum the noise figure as a function of the operating frequency is obtained. The theoretical results have been compared with experimental data obtained by the characterization of an HEMT transistor series (NE20283A, by NEC) from 6 to 18 GHz at a low noise bias point. The reported procedure exhibits good accuracy, within the typical uncertainty range of any experimental determination. The approach allows to extract all the information required for understanding the noise performance of the device without any restriction on the statistics of the noise sources. The results show the relevant noise phenomena from a new angle.
CONTESTED TERRAIN: Mining and the Environment
Authors: Bridge Gavin
Published: October 2004

▪ Abstract  This review critically surveys an extensive literature on mining, development, and environment. It identifies a significant broadening over time in the scope of the environment question as it relates to mining, from concerns about landscape aesthetics and pollution to ecosystem health, sustainable development, and indigenous rights. A typology compares and contrasts four distinctive approaches to this question: (a) technology and management-centered accounts, defining the issue in terms of environmental performance; (b) public policy studies on the design of effective institutions for capturing benefits and allocating costs of resource development; (c) structural political economy, highlighting themes of external control, resource rights, and environmental justice; and (d) cultural studies, which illustrate how mining exemplifies many of society's anxieties about the social and environmental effects of industrialization and globalization. Each approach is examined in detail.
ASSESSING THE COSTS OF ELECTRICITY
Authors: Kammen Daniel M. , Pacca Sergio
Published: October 2004

▪ Abstract  We review the economics of electricity generated, or conserved, from a diverse range of fossil-fuel, nuclear, and renewable energy sources and energy efficiency options. At the same time, we survey the methods used to compute the costs of generated and delivered electricity and power, including bus bar costs; wholesale and retail marketplace costs; life-cycle accounting systems; premiums associated with political, social, and environmental risks; costs that reflect explicit and implicit subsidies; costs inclusive of externalities calculated by a variety of means; and net costs, including a range of proposed and potential environmental tax regimes. These diverse and at times conflicting analytic methods reflect a wide range of assumptions and biases in how the inputs for energy generation as well as how the subsidies and social and environmental costs are computed or, is often the case, neglected. This review and tutorial provides side-by-side comparisons of these methods, international cost comparisons, as well as analysis of the magnitude and effects of a range of technological, market-based, and subsidy-driven costs on the final price of electricity. Comparability of costs between supply and conservation technologies and methods in the energy sector has consistently been a problem, and the diversity of energy cost accounting schemes provides significant opportunity for very different arguments to be made for specific technologies, regulatory and market regimes, and a wide range of social and environmental taxes. We provide a review of the tools and a commentary on how these methods are used to determine the cost of energy services. The conclusion contains an analysis of how these methods of energy valuation are similar, how they differ, as well as an analysis of the explicit and implicit assumptions that underlie each approach.
ELEMENTAL CYCLES: A Status Report on Human or Natural Dominance
Authors: Klee R.J. , Graedel T.E.
Published: October 2004

▪ Abstract  The modern technological society mobilizes and uses a very large number of materials. These substances are derived from rocks, sediments, and other natural repositories, and most undergo transformation prior to use. A large fraction of the materials is eventually returned to the environment. Natural processes do the same but not necessarily with the same suite of materials. For purposes of better understanding industrial development and potential environmental impact, it is important to know, even approximately, the elemental cycles of all materials potentially useful for modern technology. In this review, we examine and summarize cycle information for 77 of the first 92 elements in the periodic table. Mobilization calculations demonstrate that human activities likely dominate or strongly perturb the cycles of most of the elements other than the alkalis, alkali earths, and halogens. We propose that this pattern is ultimately related to the aqueous solubilities of the predominant chemical forms of the elements as they occur in nature: Human action dominates the cycles of the elements whose usual forms are highly insoluble, nature those that are highly soluble. Examples of the utility of anthropogenically dominated cycle determinations for resource supply analyses, environmental impact assessment, and public policy are presented and discussed. If the rapid rise in the use of materials by the technological society in the twentieth century continues into the next century, anthropogenic dominance of the cycling of a majority of the elements of the periodic table will only increase.
ENERGY MANAGEMENT AND GLOBAL HEALTH
Authors: Ezzati Majid , Bailis Robert , Kammen Daniel M. , Holloway Tracey , Price Lynn , Cifuentes Luis A. , Barnes Brendon , Chaurey Akanksha , Dhanapala Kiran N.
Published: October 2004

▪ Abstract  Energy and energy technologies have a central role in social and economic development at all scales, from household and community to regional and national. Among its welfare effects, energy is closely linked with public health both positively and negatively, the latter through environmental pollution and degradation. We review the current research on how energy use and energy technologies influence public health, emphasizing the risks associated with indoor and ambient air pollution from energy use, and the links between the local and global environmental health impacts of energy use. This review illustrates that, despite their large public health implications, most energy policies and programs in the developing world are fundamentally treated as components of overall economic development, without explicit assessment of their health benefits or hazards. Closer integration of health in energy management can facilitate the development of policies and programs that increase welfare and minimize negative health outcomes. Renewable energy technologies are used as an example of how an integrated energy-health approach can be used in policy analysis and formulation.
ADVANCES IN ENERGY FORECASTING MODELS BASED ON ENGINEERING ECONOMICS
Authors: Worrell Ernst , Ramesohl Stephan , Boyd Gale
Published: October 2004

▪ Abstract  New energy efficiency policies have been introduced around the world. Historically, most energy models were reasonably equipped to assess the impact of classical policies, such as a subsidy or change in taxation. However, these tools are often insufficient to assess the impact of alternative policy instruments. We evaluate the so-called engineering economic models used to assess future industrial energy use. Engineering economic models include the level of detail commonly needed to model the new types of policies considered. We explore approaches to improve the realism and policy relevance of engineering economic modeling frameworks. We also explore solutions to strengthen the policy usefulness of engineering economic analysis that can be built from a framework of multidisciplinary cooperation. The review discusses the main modeling approaches currently used and evaluates the weaknesses in current models. We focus on the needs to further improve the models. We identify research priorities for the modeling framework, technology representation in models, policy evaluation, and modeling of decision-making behavior.
PLANT GENETIC RESOURCES FOR FOOD AND AGRICULTURE: Assessing Global Availability
Authors: Fowler Cary , Hodgkin Toby
Published: October 2004

▪ Abstract  Plant genetic resources provide the biological underpinning for agriculture and food production. No nation is independent in terms of these resources. Interdependence levels are high among countries. Policy impediments to access may subside, increasing already substantial germplasm flows. Serious questions exist, however, about the health and availability of the actual resources. Genebank collections contain many unintended duplicates, making aggregate numbers seem larger than they really are. Information about individual accessions, particularly those found in situ, is often poor, reducing frequency and efficiency of use and ultimate benefits. Although not firmly established today, the link between conservation and use must be strengthened.
Mitochondrial regular arrangement in muscle cells: a “crystal-like” pattern
Authors: Vendelin Marko , Béraud Nathalie , Guerrero Karen , Andrienko Tatiana , Kuznetsov Andrey V. , Olivares Jose , Kay Laurence , Saks Valdur A.
Published: October 2004

The aim of this work was to characterize quantitatively the arrangement of mitochondria in heart and skeletal muscles. We studied confocal images of mitochondria in nonfixed cardiomyocytes and fibers from soleus and white gastrocnemius muscles of adult rats. The arrangement of intermyofibrillar mitochondria was analyzed by estimating the densities of distribution of mitochondrial centers relative to each other (probability density function). In cardiomyocytes (1,820 mitochondrial centers marked), neighboring mitochondria are aligned along a rectangle, with distance between the centers equal to 1.97 ± 0.43 and 1.43 ± 0.43 μm in the longitudinal and transverse directions, respectively. In soleus (1,659 mitochondrial centers marked) and white gastrocnemius (621 pairs of mitochondria marked), mitochondria are mainly organized in pairs at the I-band level. Because of this organization, there are two distances characterizing mitochondrial distribution in the longitudinal direction in these muscles. The distance between mitochondrial centers in the longitudinal direction within the same I band is 0.91 ± 0.11 and 0.61 ± 0.07 μm in soleus and white gastrocnemius, respectively. The distance between mitochondrial centers in different I bands is ∼3.7 and ∼3.3 μm in soleus and gastrocnemius, respectively. In the transverse direction, the mitochondria are packed considerably closer to each other in soleus than in white gastrocnemius, with the distance equal to 0.75 ± 0.22 μm in soleus and 1.09 ± 0.41 μm in gastrocnemius. Our results show that intermyofibrillar mitochondria are arranged in a highly ordered crystal-like pattern in a muscle-specific manner with relatively small deviation in the distances between neighboring mitochondria. This is consistent with the concept of the unitary nature of the organization of the muscle energy metabolism.
Regulation of P2X7-induced pore formation and cell death in pericyte-containing retinal microvessels
Authors: Sugiyama Tetsuya , Kawamura Hajime , Yamanishi Shigeki , Kobayashi Masato , Katsumura Kozo , Puro Donald G.
Published: October 2004

The purpose if this study was to elucidate how extracellular ATP causes cell death in the retinal microvasculature. Although ATP appears to serve as a vasoactive signal acting via P2X7 and P2Y4 purinoceptors, this nucleotide can kill microvascular cells of the retina. Because P2X7 receptor activation causes transmembrane pores to form and microvascular cells to die, we initially surmised that pore formation accounted for ATP's lethality. To test this hypothesis, we isolated pericyte-containing microvessels from rat retinas, assessed cell viability using Trypan blue dye exclusion, detected pores by determining the uptake of the fluorescent dye YO-PRO-1, measured intracellular Ca2+ with the use of fura-2, and monitored ionic currents via perforated patch pipettes. As predicted, ATP-induced cell death required P2X7 receptor activation. However, we found that pore formation was minimal because ATP's activation of P2Y4 receptors prevented P2X7 pores from forming. Rather than opening lethal pores, ATP kills via a mechanism involving voltage-dependent Ca2+ channels (VDCC). Our experiments suggest that when high concentrations of ATP caused nearly all microvascular P2X7 receptor channels to open, the resulting profound depolarization opened VDCC. Consistent with lethal Ca2+ influx via VDCC, ATP-induced cell death was markedly diminished by the VDCC blocker nifedipine or a nitric oxide (NO) donor that inhibited microvascular VDCC. We propose that purinergic vasotoxicity is normally prevented in the retina by NO-mediated inhibition of VDCC and P2Y4-mediated inhibition of P2X7 pore formation. Conversely, dysfunction of these protective mechanisms may be a previously unrecognized cause of cell death within the retinal microvasculature.
Na+/Ca2+ exchange regulates Ca2+-dependent duodenal mucosal ion transport and HCO3− secretion in mice
Authors: Dong Hui , Sellers Zachary M. , Smith Anders , Chow Jimmy Y. C. , Barrett Kim E.
Published: October 2004

Stimulation of muscarinic receptors in duodenal mucosa raises intracellular Ca2+, which regulates ion transport, including HCO3− secretion. However, the underlying Ca2+ handling mechanisms are poorly understood. The aim of the present study was to determine whether Na+/Ca2+ exchanger (NCX) plays a role in the regulation of duodenal mucosal ion transport and HCO3− secretion by controlling Ca2+ homeostasis. Mouse duodenal mucosa was mounted in Ussing chambers. Net ion transport was assessed as short-circuit current ( Isc), and HCO3− secretion was determined by pH-stat. Expression of NCX in duodenal mucosae was analyzed by Western blot, and cytosolic Ca2+ in duodenocytes was measured by fura 2. Carbachol (100 μM) increased Isc in a biphasic manner: an initial transient peak within 2 min and a later sustained plateau starting at 10 min. Carbachol-induced HCO3− secretion peaked at 10 min. 2-Aminoethoxydiphenylborate (2-APB, 100 μM) or LiCl (30 mM) significantly reduced the initial peak in Isc by 51 or 47%, respectively, and abolished the plateau phase of Isc without affecting HCO3− secretion induced by carbachol. Ryanodine (100 μM), caffeine (10 mM), and nifedipine (10 μM) had no effect on either response to carbachol. In contrast, nickel (5 mM) and KB-R7943 (10–30 μM) significantly inhibited carbachol-induced increases in duodenal mucosal Isc and HCO3− secretion. Western blot analysis showed expression of NCX1 proteins in duodenal mucosae, and functional NCX in duodenocytes was demonstrated in Ca2+ imaging experiments where Na+ depletion elicited Ca2+ entry via the reversed mode of NCX. These results indicate that NCX contributes to the regulation of Ca2+-dependent duodenal mucosal ion transport and HCO3− secretion that results from stimulation of muscarinic receptors.
Object Perception in Natural Scenes: Encoding by Inferior Temporal Cortex Simultaneously Recorded Neurons
Authors: Aggelopoulos Nikolaos C. , Franco Leonardo , Rolls Edmund T.
Published: October 2004

The firing of inferior temporal cortex neurons is tuned to objects and faces, and in a complex scene, their receptive fields are reduced to become similar to the size of an object being fixated. These two properties may underlie how objects in scenes are encoded. An alternative hypothesis suggests that visual perception requires the binding of features of the visual target through spike synchrony in a neuronal assembly. To examine possible contributions of firing synchrony of inferior temporal neurons, we made simultaneous recordings of the activity of several neurons while macaques performed a visual discrimination task. The stimuli were presented in either plain or complex backgrounds. The encoding of information of neurons was analyzed using a decoding algorithm. Ninety-four percent to 99% of the total information was available in the firing rate spike counts, and the contribution of spike timing calculated as stimulus-dependent synchronization (SDS) added only 1–6% of information to the total that was independent of the spike counts in the complex background. Similar results were obtained in the plain background. The quantitatively small contribution of spike timing to the overall information available in spike patterns suggests that information encoding about which stimulus was shown by inferior temporal neurons is achieved mainly by rate coding. Furthermore, it was shown that there was little redundancy (6%) between the information provided by the spike counts of the simultaneously recorded neurons, making spike counts an efficient population code with a high encoding capacity.
Locomotor-Like Rhythms in a Genetically Distinct Cluster of Interneurons in the Mammalian Spinal Cord
Authors: Hinckley Christopher A. , Hartley Robert , Wu Linying , Todd Andrew , Ziskind-Conhaim Lea
Published: October 2004

Electrophysiological and morphological properties of genetically identified spinal interneurons were examined to elucidate their possible contribution to locomotor-like rhythmic activity in 1- to 4-day-old mice. In the transgenic mice used in our study, the HB9 promotor controlled the expression of the reporter gene enhanced green fluorescent protein (eGFP), giving rise to GFP+ motoneurons and ventral interneurons. However, only motoneurons and a small group of bipolar, GFP+ interneurons expressed the HB9 protein. The HB9+/GFP+ interneurons were clustered close to the medial surface in lamina VIII along segments L1–L3. The correlation between activity pattern in these visually identified interneurons and motoneuron output was examined using simultaneous whole cell and ventral root recordings. Neurochemically induced rhythmic membrane depolarizations in HB9/GFP interneurons were synchronous with ventral root rhythms, indicating that the interneurons received synaptic inputs from rhythm-generating networks. The frequency of excitatory postsynaptic currents significantly increased during ventral root bursts, but there was no change in the frequency of inhibitory postsynaptic currents during the cycle period. These data implied that HB9/GFP interneurons received primarily excitatory inputs from rhythmogenic interneurons. Neurobiotin-filled axon terminals were in close apposition to other neurons in the cluster and to motoneuron dendrites, raising the possibility that HB9/GFP interneurons formed synaptic connections with each other and with motoneurons. The expression of the vesicular glutamate transporter 2 in axon terminals of HB9/GFP interneurons indicated that these were glutamatergic interneurons. Our findings suggest that the visually identified HB9/GFP interneurons are premotor excitatory interneurons and putative constituents of networks generating locomotor rhythms in the mammalian spinal cord.
Blue-Yellow Signals Are Enhanced by Spatiotemporal Luminance Contrast in Macaque V1
Authors: Horwitz Gregory D. , Chichilnisky E. J. , Albright Thomas D.
Published: October 2004

We measured the color tuning of a population of S-cone-driven V1 neurons in awake, fixating monkeys. Analysis of randomly chosen color stimuli that were effective in evoking action potentials showed that these neurons received opposite sign input from the S cones and a combination of L and M cones. Surprisingly, these cells also responded to LM cone contrast irrespective of polarity, a nonlinear sensitivity that was masked by conventional linear analysis methods. Taken together, these observations can be summarized in a nonlinear model that combines nonopponent and opponent signals such that luminance contrast enhances color processing. These findings indicate that important aspects of the cortical representation of color cannot be described by classical linear analysis, and reveal a possible neural correlate of perceptual color-luminance interactions.
Inter-residue distances derived from fold contact propensities correlate with evolutionary substitution costs
Authors: Williams Gareth , Doherty Patrick
Published: October 2004

Background

The wealth of information on protein structure has led to a variety of statistical analyses of the role played by individual amino acid types in the protein fold. In particular, the contact propensities between the various amino acids can be converted into folding energies that have proved useful in structure prediction. The present study addresses the relationship of protein folding propensities to the evolutionary relationship between residues.

Results

The contact preferences of residue types observed in a representative sample of protein structures are converted into a residue similarity matrix or inter-residue distance matrix. Remarkably, these distances correlate excellently with evolutionary substitution costs. Residue vectors are derived from the distance matrix. The residue vectors give a concrete picture of the grouping of residues into families sharing properties crucial for protein folding.

Conclusions

Inter-residue distances have proved useful in showing the explicit relationship between contact preferences and evolutionary substitution rates. It is proposed that the distance matrix derived from structural analysis may be useful in aligning proteins where remote homologs share structural features. Residue vectors derived from the distance matrix illustrate the spatial arrangement of residues and point to ways in which they can be grouped.
Two Drosophila suppressors of cytokine signaling (SOCS) differentially regulate JAK and EGFR pathway activities
Authors: Rawlings Jason S , Rennebeck Gabriela , Harrison Susan MW , Xi Rongwen , Harrison Douglas A
Published: October 2004

Background

The Janus kinase (JAK) cascade is an essential and well-conserved pathway required to transduce signals for a variety of ligands in both vertebrates and invertebrates. While activation of the pathway is essential to many processes, mutations from mammals and Drosophila demonstrate that regulation is also critical. The SOCS (S uppressor O f C ytokine S ignaling) proteins in mammals are regulators of the JAK pathway that participate in a negative feedback loop, as they are transcriptionally activated by JAK signaling. Examination of one Drosophila SOCS homologue, Socs36E, demonstrated that its expression is responsive to JAK pathway activity and it is capable of downregulating JAK signaling, similar to the well characterized mammalian SOCS.

Results

Based on sequence analysis of the Drosophila genome, there are three identifiable SOCS homologues in flies. All three are most similar to mammalian SOCS that have not been extensively characterized: Socs36E is most similar to mammalian SOCS5, while Socs44A and Socs16D are most similar to mammalian SOCS6 and 7. Although Socs44A is capable of repressing JAK activity in some tissues, its expression is not regulated by the pathway. Furthermore, Socs44A can enhance the activity of the EGFR/MAPK signaling cascade, in contrast to Socs36E.

Conclusions

Two Drosophila SOCS proteins have some overlapping and some distinct capabilities. While Socs36E behaves similarly to the canonical vertebrate SOCS, Socs44A is not part of a JAK pathway negative feedback loop. Nonetheless, both SOCS regulate JAK and EGFR signaling pathways, albeit differently. The non-canonical properties of Socs44A may be representative of the class of less characterized vertebrate SOCS with which it shares greatest similarity.
Serum adiponectin as a biomarker for in vivo PPARgamma activation and PPARgamma agonist-induced efficacy on insulin sensitization/lipid lowering in rats
Authors: Yang Baichun , Brown Kathleen K , Chen Lihong , Carrick Kevin M , Clifton Lisa G , McNulty Judi A , Winegar Deborah A , Strum Jay C , Stimpson Stephen A , Pahel Gregory L
Published: October 2004

Background

PPARγ agonists ameliorate insulin resistance and dyslipidemia in type 2 diabetic patients. Adiponectin possesses insulin sensitizing properties, and predicts insulin sensitivity of both glucose and lipid metabolism. In diet-induced insulin resistant rats and ZDF rats, the current studies determined the correlation between PPARγ agonist-upregulated fatty acid binding protein(FABP3) mRNA in adipose tissue and PPARγ agonist-elevated serum adiponectin, and the correlation between PPARγ agonist-elevated serum adiponectin and PPARγ agonist-mediated efficacy in insulin sensitization and lipid lowering.

Results

Parallel groups of SD rats were fed a high fat/sucrose (HF) diet for 4 weeks. These rats were orally treated for the later 2 weeks with vehicle, either PPARγ agonist GI262570 (0.2–100 mg/kg, Q.D.), or GW347845 (3 mg/kg, B.I.D). Rats on HF diet showed significant increases in postprandial serum triglycerides, free fatty acids (FFA), insulin, and area under curve (AUC) of serum insulin during an oral glucose tolerance test, but showed no change in serum glucose, adiponectin, and glucose AUC. Treatment with GI262570 dose-dependently upregulated adipose FABP3 mRNA, and increased serum adiponectin. There was a positive correlation between adipose FABP3 mRNA and serum adiponectin (r = 0.7350, p < 0.01). GI262570 dose-dependently decreased the diet-induced elevations in triglycerides, FFA, insulin, and insulin AUC. Treatment with GW347845 had similar effects on serum adiponectin and the diet-induced elevations. There were negative correlations for adiponectin versus triglycerides, FFA, insulin, and insulin AUC (For GI262570, r = -0.7486, -0.4581, -0.4379, and -0.3258 respectively, all p < 0.05. For GW347845, r = -0.6370, -0.6877, -0.5512, and -0.3812 respectively, all p < 0.05). In ZDF rats treated with PPARγ agonists pioglitazone (3–30 mg/kg, B.I.D.) or GW347845 (3 mg/kg, B.I.D.), there were also negative correlations for serum adiponectin versus glucose, triglycerides, FFA (for pioglitazone, r = -0.7005, -0.8603, and -0.9288 respectively; for GW347845, r = -0.9721, -0.8483, and -0.9453 respectively, all p < 0.01).

Conclusions

This study demonstrated that (a) PPARγ agonists improved insulin sensitivity and ameliorated dyslipidemia in HF fed rats and ZDF rats, which were correlated with serum adiponectin; (b) Serum adiponectin was positively correlated with adipose FABP3 mRNA in GI262570-treated rats. These data suggest that serum adiponectin can serve as a biomarker for both in vivo PPARγ activation and PPARγ agonist-induced efficacy on insulin resistance and dyslipidemia in rats.