bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Investigation of the Solar Carbothermic Reduction of ZnO Using a Two-cavity Solar Reactor
Authors: Osinga T. , Frommherz U. , Steinfeld A. , Wieckert C.
Published: February 2004

Zinc production by solar carbothermic reduction of ZnO offers a CO2 emission reduction by a factor of 5 vis-a`-vis the conventional fossil-fuel-based electrolytic or Imperial Smelting processes. Zinc can serve as a fuel in Zn-air fuel cells or can be further reacted with H2O to form high-purity H2. In either case, the product ZnO is solar-recycled to Zn. We report on experimental results obtained with a 5 kW solar chemical reactor prototype that features two cavities in series, with the inner one functioning as the solar absorber and the outer one as the reaction chamber. The inner cavity is made of graphite and contains a windowed aperture to let in concentrated solar radiation. The outer cavity is well insulated and contains the ZnO-C mixture that is subjected to irradiation from the inner graphite cavity. With this arrangement, the inner cavity protects the window against particles and condensable gases and further serves as a thermal shock absorber. Tests were conducted at PSI’s Solar Furnace and ETH’s High-Flux Solar Simulator to investigate the effect of process temperature (range 1350-1600 K), reducing agent type (beech charcoal, activated charcoal, petcoke), and C:ZnO stoichiometric molar ratio (range 0.7–0.9) on the reactor’s performance and chemical conversion. In a typical 40-min solar experiment at 1500 K, 500 g of a ZnO-C mixture were processed into Zn(g), CO, and CO2. Thermal efficiencies of up to 20% were achieved.
Optimal Outside Airflow Control of an Integrated Air-Handling Unit System for Large Office Buildings
Authors: Song L. , Liu M.
Published: February 2004

This paper presents optimal outside air control schedules for an integrated air-handling unit system for large commercial buildings (OAHU). The schedules are developed using the geometric linear optimization method and expressed as analytical functions of the outside air temperature and enthalpy, the interior zone airflow ratio, and the exterior zone supply air temperature. The optimal outside air control schedules can be applied to both constant and variable air volume systems. When the schedules are implemented, the OAHU system can significantly improve indoor air quality (IAQ) and use significantly less thermal energy than conventional systems. The geometric optimization method can also be used in other linear HVAC optimizations with non-liner constraint conditions.
The diffraction and spreading of a wavepacket
Authors: Vandegrift Guy
Published: February 2004

The spreading of a one-dimensional wavepacket solution of Schrödinger’s equation is related to the diffraction of light, as can be verified by considering the three-dimensional spreading of a wavepacket for an arbitrary dispersion relation. This investigation uncovers a special property of Schrödinger’s equation for a free particle: A wavepacket with initial spherical symmetry will preserve this symmetry in all Galilean reference frames. This property leads to a derivation of de Broglie’s postulate that wave number is proportional to momentum (or velocity). The application to non-Gaussian wavepackets and to Fraunhoffer diffraction also is discussed.
Putting your heart into physics
Authors: Siegel P. B. , Urhausen A. , Sperber J. , Kindermann W.
Published: February 2004

We describe techniques for measuring the time interval between successive heartbeats. This time series data can be used in undergraduate physics classes for instruction in resonance phenomena, scaling, and other methods of analysis including Fourier analysis and Poincaré plots. Using methods from physics on data from human physiology are of particular interest to life science students.
A new appraisal of old formulations of mechanics
Authors: Drago Antonino
Published: February 2004

Lazare Carnot’s formulation of mechanics (1783) is re-evaluated in relation to other formulations of classical mechanics and modern theories.
Effective interactions and the hydrogen atom
Authors: Holstein Barry R.
Published: February 2004

The technique of effective interactions, which has become commonplace in contemporary particle/nuclear physics, is used to analyze the structure of hydrogen atom energy levels.
Heisenberg in Poland
Authors: Bernstein Jeremy
Published: February 2004

While much is known about Heisenberg’s visit to Copenhagen in 1941 little has been written about his visit to Poland two years later. This article attempts to fill in the gap.
Path integral in a magnetic field using the Trotter product formula
Authors: Gaveau B. , Mihóková E. , Roncadelli M. , Schulman L. S.
Published: February 2004

The derivation of the Feynman path integral based on the Trotter product formula is extended to the case where the system is in a magnetic field.
Unified equations for the slope, intercept, and standard errors of the best straight line
Authors: York Derek , Evensen Norman M. , Martı́nez Margarita López , De Basabe Delgado Jonás
Published: February 2004

It has long been recognized that the least-squares estimation method of fitting the best straight line to data points having normally distributed errors yields identical results for the slope and intercept of the line as does the method of maximum likelihood estimation. We show that, contrary to previous understanding, these two methods also give identical results for the standard errors in slope and intercept, provided that the least-squares estimation expressions are evaluated at the least-squares-adjusted points rather than at the observed points as has been done traditionally. This unification of standard errors holds when both x and y observations are subject to correlated errors that vary from point to point. All known correct regression solutions in the literature, including various special cases, can be derived from the original York equations. We present a compact set of equations for the slope, intercept, and newly unified standard errors.
Creating a distributed physics department
Authors: Balasubramanya M. K. , Cox P. H. , Hewett L. D. , Leckenby H. , Suson D. J. , Espinosa J. , Gonzalez O. , Ni Q. , Lawrence P. J. , Marble D. K. , Willson V. L.
Published: February 2004

To preserve their undergraduate physics programs, a group of state universities in Texas has jointly offered upper level undergraduate physics courses through the Texas Electronic Coalition for Physics for the past nine years. At the start of the 2002 academic year they formalized their relationship to successfully create a fully functioning distributed physics department. We report on the status of this innovative project, the inter-institutional organizational structures that have evolved to support this initiative, the successes achieved by the distributed department during its first year, and the problems encountered and possible solutions.
Jacobi’s 1842 solution of the inverse-square problem
Authors: Gauthier N.
Published: February 2004

In a memoir written in Latin, Jacobi published in 1842 a simple, concise, and elegant solution of the inverse-square problem. This note argues that Jacobi’s solution has not attracted the attention that it deserves and that it should prove valuable to teachers and students in introductory mechanics courses. A translation of the excerpt in which Jacobi describes his solution is given, and the method is then recast in the now more familiar language of vectors.
Structural Basis of Transcription: An RNA Polymerase II-TFIIB Cocrystal at 4.5 Angstroms
Authors: Bushnell David A. , Westover Kenneth D. , Davis Ralph E. , Kornberg Roger D.
Published: February 2004

The structure of the general transcription factor IIB (TFIIB) in a complex with RNA polymerase II reveals three features crucial for transcription initiation: an N-terminal zinc ribbon domain of TFIIB that contacts the “dock” domain of the polymerase, near the path of RNA exit from a transcribing enzyme; a “finger” domain of TFIIB that is inserted into the polymerase active center; and a C-terminal domain, whose interaction with both the polymerase and with a TATA box–binding protein (TBP)–promoter DNA complex orients the DNA for unwinding and transcription. TFIIB stabilizes an early initiation complex, containing an incomplete RNA-DNA hybrid region. It may interact with the template strand, which sets the location of the transcription start site, and may interfere with RNA exit, which leads to abortive initiation or promoter escape. The trajectory of promoter DNA determined by the C-terminal domain of TFIIB traverses sites of interaction with TFIIE, TFIIF, and TFIIH, serving to define their roles in the transcription initiation process.
Improving the Density of Jammed Disordered Packings Using Ellipsoids
Authors: Donev Aleksandar , Cisse Ibrahim , Sachs David , Variano Evan A. , Stillinger Frank H. , Connelly Robert , Torquato Salvatore , Chaikin P. M.
Published: February 2004

Packing problems, such as how densely objects can fill a volume, are among the most ancient and persistent problems in mathematics and science. For equal spheres, it has only recently been proved that the face-centered cubic lattice has the highest possible packing fraction

\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\varphi}={\pi}{/}\sqrt{18}{\approx}0.74\) \end{document}

. It is also well known that certain random (amorphous) jammed packings have φ ≈ 0.64. Here, we show experimentally and with a new simulation algorithm that ellipsoids can randomly pack more densely—up to φ= 0.68 to 0.71for spheroids with an aspect ratio close to that of M&M's Candies—and even approach φ ≈ 0.74 for ellipsoids with other aspect ratios. We suggest that the higher density is directly related to the higher number of degrees of freedom per particle and thus the larger number of particle contacts required to mechanically stabilize the packing. We measured the number of contacts per particle
Z
≈ 10 for our spheroids, as compared to
Z
≈ 6 for spheres. Our results have implications for a broad range of scientific disciplines, including the properties of granular media and ceramics, glass formation, and discrete geometry.
Renewable Hydrogen from Ethanol by Autothermal Reforming
Authors: Deluga G. A. , Salge J. R. , Schmidt L. D. , Verykios X. E.
Published: February 2004

Ethanol and ethanol-water mixtures were converted directly into H
2
with ∼100% selectivity and >95% conversion by catalytic partial oxidation, with a residence time on rhodium-ceria catalysts of <10 milliseconds.Rapid vaporization and mixing with air with an automotive fuel injector were performed at temperatures sufficiently low and times sufficiently fast that homogeneous reactions producing carbon, acetaldehyde, ethylene, and total combustion products can be minimized.This process has great potential for low-cost H
2
generation in fuel cells for small portable applications where liquid fuel storage is essential and where systems must be small, simple, and robust.
Modulation of Th1 Activation and Inflammation by the NF-κB Repressor Foxj1
Authors: Lin Ling , Spoor Melanie S. , Gerth Andrea J. , Brody Steven L. , Peng Stanford L.
Published: February 2004

Forkhead transcription factors play key roles in the regulation of immune responses. Here, we identify a role for one member of this family, Foxj1, in the regulation of T cell activation and autoreactivity. Foxj1 deficiency resulted in multiorgan systemic inflammation, exaggerated Th1 cytokine production, and T cell proliferation in autologous mixed lymphocyte reactions. Foxj1 suppressed NF-κB transcription activity in vitro, and Foxj1-deficient T cells possessed increased NF-κB activity in vivo, correlating with the ability of Foxj1 to regulate IκB proteins, particularly IκBβ. Thus, Foxj1 likely modulates inflammatory reactions and prevents autoimmunity by antagonizing proinflammatory transcriptional activities. These results suggest a potentially general role for forkhead genes in the enforcement of lymphocyte quiescence.
Consistent Cytotoxic-T-Lymphocyte Targeting of Immunodominant Regions in Human Immunodeficiency Virus across Multiple Ethnicities
Authors: Frahm Nicole , Korber B. T. , Adams C. M. , Szinger J. J. , Draenert R. , Addo M. M. , Feeney M. E. , Yusim K. , Sango K. , Brown N. V. , SenGupta D. , Piechocka-Trocha A. , Simonis T. , Marincola F. M. , Wurcel A. G. , Stone D. R. , Russell C. J. , Adolf P. , Cohen D. , Roach T. , StJohn A. , Khatri A. , Davis K. , Mullins J. , Goulder P. J. R. , Walker B. D. , Brander C.
Published: February 2004

Although there is increasing evidence that virus-specific cytotoxic-T-lymphocyte (CTL) responses play an important role in the control of human immunodeficiency virus (HIV) replication in vivo, only scarce CTL data are available for the ethnic populations currently most affected by the epidemic. In this study, we examined the CD8+-T-cell responses in African-American, Caucasian, Hispanic, and Caribbean populations in which clade B virus dominates and analyzed the potential factors influencing immune recognition. Total HIV-specific CD8+-T-cell responses were determined by enzyme-linked immunospot assays in 150 HIV-infected individuals by using a clade B consensus sequence peptide set spanning all HIV proteins. A total of 88% of the 410 tested peptides were recognized, and Nef- and Gag-specific responses dominated the total response for each ethnicity in terms of both breadth and magnitude. Three dominantly targeted regions within these proteins that were recognized by >90% of individuals in each ethnicity were identified. Overall, the total breadth and magnitude of CD8+-T-cell responses correlated with individuals' CD4 counts but not with viral loads. The frequency of recognition for each peptide was highly correlated with the relative conservation of the peptide sequence, the presence of predicted immunoproteasomal cleavage sites within the C-terminal half of the peptide, and a reduced frequency of amino acids that impair binding of optimal epitopes to the restricting class I molecules. The present study thus identifies factors that contribute to the immunogenicity of these highly targeted and relatively conserved sequences in HIV that may represent promising vaccine candidates for ethnically heterogeneous populations.
AN EVOLUTIONARY ALGORITHM FOR PURE FUZZY FLOWSHOP SCHEDULING PROBLEMS
Authors: CELANO G. , COSTA A. , FICHERA S.
Published: February 2004

The pure flowshop scheduling problem is here investigated from a perspective considering me uncertainty associated with the execution of shop floor activities. Being the flowshop problem is NP complete, a large number of heuristic algorithms have been proposed in literature to determine an optimal solution. Unfortunately, these algorithms usually assume a simplifying hypothesis: the problem data are assumed as deterministic, i.e. job processing times and the due dates are expressed through a unique value, which does not reflect the real process variability. For this reason, some authors have recently proposed the use of a fuzzy set theory to model the uncertainty in scheduling problems. In this paper, a proper genetic algorithm has been developed for solving the fuzzy flowshop scheduling problem. The optimisation involves two different objectives: the completion time minimisation and the due date fulfilment; both the single and multi-objective configurations have been considered. A new ranking criterion has been proposed and its performance has been tested through a set of test problems. A numerical analysis confirms the efficiency of the proposed optimisation procedure.
STEP REARRANGEMENT UPON LOW PRESSURE OXIDATION OF THE Pt3Ti(510) SURFACE: A STUDY BY SCANNING TUNNELING MICROSCOPY
Authors: KURZINA I. , SHEVLYUGA V. , ATREI A. , CORTIGIANI B. , ROVIDA G. , BARDI U.
Published: February 2004

The oxidation of the single crystal stepped Pt 3 Ti (510) surface at oxygen pressures below 10-5 mbar and at a temperature of 770 K was studied by means of X-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS) and low energy electron diffraction (LEED). Scanning tunneling microscopy (STM) was used to follow the evolution of the surface morphology on the atomic scale. The clean surface studied in ultrahigh vacuum conditions was found by LEIS to be composed of platinum only in the outermost surface plane. LEED and STM indicate that the clean Pt 3 Ti (510) surface consists of (100) terraces separated by double atomic steps. The exposure of the clean surface to oxygen at pressures in the range of 10-7–10-5 mbar leads to the growth of a titanium oxide layer (with a composition close to TiO) which covers completely the substrate surface. The TiO film has long range order and exhibits complex LEED patterns. The STM measurements indicate that the ordered array of steps is kept in the early stages of the oxide film growth, whereas a change of the step morphology and step orientation is observed during the oxidation process.
STUDY OF THE C2H4/Si(100)-(2×1) INTERFACE BY DERIVATIVE PHOTOELECTRON HOLOGRAPHY
Authors: XU S. H. , WU H. S. , TONG S. Y. , KEEFFE M. , LAPEYRE G. J. , ROTENBERG E.
Published: February 2004

The k derivative spectra (KDS) transform is used for construction of the three-dimensional atomic structure of the C 2 H 4/ Si (100)-(2×1) system from photoelectron diffraction data. The image function obtained by the KDS transform clearly observes the second-layer Si atoms and the C emitters apart from the first-layer Si atoms. The observations of the second-layer Si atoms and the C emitters make it easy to measure the C–C bond length correctly. Then a conclusive adsorption model — the di-σ model — for the C 2 H 4/ Si (100)-(2×1) system is established. In comparison with the KDS transform, the normal small-cone transform hardly measures the C–C bond length. The ability to observe more scatterers of a photoelectron emitter by the KDS transform expands the applicability of holographic imaging.
KINETIC AND REACTIVE PROPERTIES OF ETHYLENE ON CLEAN AND HYDROGEN-COVERED Pd(111)
Authors: BURKHOLDER L. , STACCHIOLA D. , TYSOE W. T.
Published: February 2004

Several molecular adsorption states are identified following ethylene adsorption on clean and hydrogen-covered Pd(111) using temperature-programmed desorption (TPD) and reflection absorption infrared spectroscopy (RAIRS). Di-σ-bonded ethylene forms on clean Pd(111) desorbing with an activation energy of 80 kJ/mol at low coverages. The strong intermolecular lateral interactions considerably reduce the desorption temperature at higher coverages. Π-bonded ethylene is formed on hydrogen-covered Pd(111), where the proportion of π-bonded species increases with hydrogen coverage. This species converts to the more stable di-σ-bonded species on heating. Ethane formation is detected in TPD from hydrogen-precovered Pd(111), which is predominantly formed by reaction with π-bonded ethylene.
ATOMIC-COORDINATION-IMPERFECTION-ENHANCED Pd-3d5/2 CRYSTAL BINDING ENERGY
Authors: SUN CHANG Q.
Published: February 2004

Crystal binding energy of a core electron at the 3d 5/2 level of a Pd atom has been estimated to be -4.0±0.02 eV by decoding the X-ray photoelectron spectra obtained from both the Pd surfaces and the Pd nanoparticles. Findings indicate that the increase in the binding energy originates from the effect of coordination number (CN) imperfection of atoms at a flat surface or at the curved surface of a nanosolid. The CN imperfection shortens the remaining bonds of the lower-coordinated atoms spontaneously associated with bond energy increase, which perturbs the Hamiltonian of an extended solid and hence shifts the core level to higher binding energy. Therefore, the significance of atomic CN imperfection cannot be overlooked in dealing with a low-dimensional system, and the recent bond-order–length–strength (BOLS) correlation mechanism is essentially adequate, for the significance of atomic CN imperfection.
ELECTRICAL CONDUCTION THROUGH SURFACE SUPERSTRUCTURES MEASURED BY MICROSCOPIC FOUR-POINT PROBES
Authors: HASEGAWA SHUJI , SHIRAKI ICHIRO , TANABE FUHITO , HOBARA REI , KANAGAWA TAIZO , TANIKAWA TAKEHIRO , MATSUDA IWAO , PETERSEN CHRISTIAN L. , HANSEN TORBEN M. , BOGGILD PETER , GREY FRANCOIS
Published: February 2004

For in-situ measurements of the local electrical conductivity of well-defined crystal surfaces in ultrahigh vacuum, we have developed two kinds of microscopic four-point probe methods. One involves a "four-tip STM prober," in which four independently driven tips of a scanning tunneling microscope (STM) are used for measurements of four-point probe conductivity. The probe spacing can be changed from 500 nm to 1 mm. The other method involves monolithic micro-four-point probes, fabricated on silicon chips, whose probe spacing is fixed around several μm. These probes are installed in scanning-electron-microscopy/electron-diffraction chambers, in which the structures of sample surfaces and probe positions are observed in situ. The probes can be positioned precisely on aimed areas on the sample with the aid of piezoactuators. By the use of these machines, the surface sensitivity in conductivity measurements has been greatly enhanced compared with the macroscopic four-point probe method. Then the conduction through the topmost atomic layers (surface-state conductivity) and the influence of atomic steps on conductivity can be directly measured.
INVESTIGATION OF THE ENERGETICS OF THE DECOMPOSITION OF AZOMETHANE ONPd(111): THE UBI–QEP APPROACH
Authors: AZIZIAN S. , GOBAL F.
Published: February 2004

The method of unity bond index–quadratic exponential potential (UBI–QEP) is employed to derive the energetic parameters associated with the steps of the pathway which we propose for the catalytic decomposition of azomethane on the Pd (111) surface. According to the energy calculations, azomethane adsorbs molecularly in trans-configuration and then decomposes to CH3N with no activation energy. The reaction continues by tilting and dehydrogenation to the products ( H2and HCN). The calculated activation energies at various surface coverages perfectly account for the variation of relative yields of H2and HCN with changing of the coverage of azomethane. According to the calculations, desorption of molecular azomethane at high surface coverage occurs, which is in excellent agreement with experimental data.
THE EFFECT OF H ON THE ELECTRONIC STRUCTURE OF AN Fe(110)–Pd(100) INTERFACE
Authors: JASEN PAULA V. , GONZALEZ ESTELA A. , NAGEL OSCAR A. , JUAN ALFREDO
Published: February 2004

The ion-driven mechanism in hydrogen permeation is substantially modified when iron is coated with palladium. A detailed knowledge of the electronic structure at the metal–metal interfaces is a prerequisite for understanding the process of H permeation. We have selected two low-Miller-index surfaces as a simple model for the interface. The system under consideration has 148 metallic atoms forming an Fe–Pd cluster distributed in six metallic layers.

We have investigated the interaction of atomic hydrogen with the Fe (110)– Pd (100) interface using the semiempirical atom superposition and electron delocalization (ASED-MO) method. The changes in the electronic structures, density of states (DOS) and crystal overlap orbital population (COOP) in two different Fe–Pd interfaces were compared with the bulk ground states of both metals.

The interfacial Fe–Pd distance results in about 1.74 Å, whereas for the Fe–Pd first neighbors distance it is about 1.85 Å. An important conclusion is that the metal–metal bonds at the interface are stronger than those bonds in the pure metal bulk. A favorable metal adhesion is observed, as revealed by the energetic stabilization of the composite metal system.

H is stabilized near the FePd interface and stopped at the first Pd layer. A H–metal bond is developed with both Fe and Pd atoms while Fe–Pd bonding at the interface remains unaltered.
LONG-SHORT PORTFOLIO MODELING: CRITIQUE AND EXTENSION
Authors: KWAN CLARENCE C. Y.
Published: February 2004

This study offers a critique of a recent IJTAF article by Charpin and Lacaze that formulates and solves a long-short portfolio selection problem. This study not only addresses some analytical issues arising from their model formulation but also provides a revised version and some properties of the corresponding efficient portfolios. Further, the revised formulation is extended to accommodate other practical features of long-short investing. This study is intended to enhance the usefulness of long-short portfolio modeling in practice.
THE CHARPIN–LACAZE RESPONSE TO C. C. Y. KWAN'S PAPER "LONG-SHORT PORTFOLIO MODELING: CRITIQUE AND EXTENSION"
Authors: CHARPIN FRANÇOISE , LACAZE DOMINIQUE
Published: February 2004

With this note, we refute Kwan's criticism. On one hand, the choice of an inequality budget constraint allows us, for μ greater than μ0, to study the useful part of the efficient frontier. On the other hand, the assumption that the cost of constructing long-short portfolios is positive, seems quite reasonable when transactions costs are included. Finally, we consider Kwan's revised model and explain why his formulation does not work.
LONG-SHORT STRATEGIES: AN EXTENSION
Authors: CHARPIN FRANÇOISE , LACAZE DOMINIQUE
Published: February 2004

This note supplements the paper by Charpin and Lacaze [1], which studied the efficient frontier of long-short portfolios taking regulations into account. The long-short portfolios were constructed using purchases on margin and short sales. We now introduce the possibility of making cash purchases (in addition to margin purchases) which can then be used as collateral for short selling. We first present the model, which encompasses our previous one. We then describe the potential gain from this new model, showing that it is likely to be negligible. A numerical resolution confirms this point.
LONG MEMORY AND PERSISTENCE IN DOLLAR-BASED REAL EXCHANGE RATES
Authors: SIOKIS FOTIOS , CHRISTODOULOU CHRIS
Published: February 2004

A common view among recent studies on purchasing power parity is that the post-Bretton Woods period is far too short to reveal any significant parity reversion in individual series of real exchange rates. The answer depends on the statistical techniques being used. This study uses alternative econometric time-series technique, which does not require long sample sizes, and reports strong evidence of mean reversion in dollar-based real exchange rates. Further analysis of the estimated impulse responses indicates that the persistence in real exchange rate changes is difficult to detect because the short and long run dynamics interact in such a way that the impulse response weights exhibit a rapid decay.
DIVIDENDS AND UNCERTAINTY: EVIDENCE FROM THE ITALIAN MARKET
Authors: BATTAUZ ANNA , BECCACECE FRANCESCA
Published: February 2004

In this paper we investigate the behavior of the market around dividend payment dates. Our empirical analysis, based on a Bayesian approach applied to Italian stock data, confirms the presence of abnormal returns at the ex-dividend date, as already documented in the literature for other markets. Calibrating a suitable model introduced in [1] to take care of the additional randomness pertubing the market around dividend payment dates, we investigate the effects on the derivative evaluation. Looking at the NoArbitrage prices of American call options written on some Italian dividend-paying stock and comparing them with the marketed prices, we conclude that the effect of this additional randomness can be neglected.
PRICING DERIVATIVE SECURITIES USING CROSS-ENTROPY: AN ECONOMIC ANALYSIS
Authors: BRANGER NICOLE
Published: February 2004

This paper analyses two implied methods to determine the pricing function for derivatives when the market is incomplete. First, we consider the choice of an equivalent martingale measure with minimal cross-entropy relative to a given benchmark measure. We show that the choice of the numeraire has an impact on the resulting pricing function, but that there is no sound economic answer to the question which numeraire to choose. The ad-hoc choice of the numeraire introduces an element of arbitrariness into the pricing function, thus contradicting the motivation of this method as the least prejudiced way to choose the pricing operator. Second, we propose two new methods to select a pricing function: the choice of the stochastic discount factor (SDF) with minimal extended cross-entropy relative to a given benchmark SDF, and the choice of the Arrow–Debreu (AD) prices with minimal extended cross-entropy relative to some set of benchmark AD prices. We show that these two methods are equivalent in that they generate identical pricing functions. They avoid the dependence on the numeraire and replace it by the dependence on the benchmark pricing function. This benchmark pricing function, however, can be chosen based on economic considerations, in contrast to the arbitrary choice of the numeraire.
Algebraic properties of a digraph and its line digraph
Authors: Balbuena C. , Ferrero D. , Marcote X. , Pelayo I.
Published: February 2004

Let G be a digraph, LG its line digraph and A(G) and A(LG) their adjacency matrices. We present relations between the Jordan Normal Form of these two matrices. In addition, we study the spectra of those matrices and obtain a relationship between their characteristic polynomials that allows us to relate properties of G and LG, specifically the number of cycles of a given length.
Layout Area of the Hypercube
Authors: Even Shimon , Kupershtok Roni
Published: February 2004

In this paper we study the square grid area required for laying out Hl, the Boolean hypercube of N=2l vertices. It is shown that this area is [Formula: see text]. We describe a layout which occupies this much area and prove that no layout of less area exists.
Optimal Neighborhood Broadcast in Star Graphs
Authors: Fujita Satoshi
Published: February 2004

In this paper, we consider the problem of constructing a multicast tree in star interconnection networks under the single-port communication model. Unlike previous schemes for constructing space-efficient multicast trees, we adopt the completion time of each multicast as the objective function to be minimized. In particular, we study a special case of the problem in which all destination vertices are immediate neighbors of the source vertex, and propose a multicast scheme of [Formula: see text] time units for the star graph of dimension n.
Fault-Tolerant Routing in Wormhole Meshes
Authors: Tsai Ming-Jer
Published: February 2004

In wormhole meshes, many a routing algorithm prevents a deadlock by enclosing unlimited number of faulty nodes with faulty blocks and dividing a physical interconnection network into a fixed number of virtual ones; none of them, however, is able to tolerate two faulty blocks with a distance of two, no less, in at least one dimension by use of only two virtual interconnection networks. To fill this gap, an adaptive and fault-tolerant routing algorithm is proposed. The algorithm is fully-adaptive until encountering a faulty block. It then detours the blocked message around the faulty block. Arranging the detours around faulty blocks attempts to prevent a deadlock. The proposed method has no need for global information.
The Extracellular Cyclic AMP-Adenosine Pathway in Renal Physiology
Authors: Jackson Edwin K. , Raghvendra Dubey K.
Published: February 2004

▪ Abstract  Many cell types in the kidney express adenosine receptors, and adenosine has multiple effects on renal function. Although adenosine is produced within the kidney by several biochemical reactions, recent studies support a novel mechanism for renal adenosine production, the extracellular cAMP-adenosine pathway. This extracellular cAMP-adenosine pathway is initiated by efflux of cAMP from cells following activation of adenylyl cyclase. Extracellular cAMP is then converted to adenosine by the serial actions of ecto-phosphodiesterase and ecto-5′-nucleotidase. When extracellular cAMP is converted to adenosine near the biophase of cAMP production and efflux, this local extracellular cAMP-adenosine pathway permits tight coupling of the site of adenosine production to the site of adenosine receptors. cAMP in renal compartments may also be formed by tissues/organs remote from the kidney. For example, stimulation of hepatic adenylyl cyclase by the pancreatic hormone glucagon increases circulating cAMP, which is filtered at the glomerulus and concentrated in the tubular lumen as water is extracted from the ultrafiltrate. Conversion of hepatic-derived cAMP to adenosine in the kidney completes a pancreatohepatorenal cAMP-adenosine pathway that may serve as an endocrine link between the pancreas, liver, and kidney.
Regulation of Renal K Transport by Dietary K Intake
Authors: Wang WenHui
Published: February 2004

▪ Abstract  Extracellular K must be kept within a narrow concentration range for the normal function of neurons, skeletal muscle, and cardiac myocytes. Maintenance of normal plasma K is achieved by a dual mechanism that includes extrarenal factors such as insulin and β-adrenergic agonists, which stimulate the movement of K from extracellular to intracellular fluid and modulate renal K excretion. Dietary K intake is an important factor for the regulation of K secretion: An increase in K intake stimulates secretion, whereas a decrease inhibits K secretion and enhances absorption. This effect of changes in dietary K intake on tubule K transport is mediated by aldosterone-dependent and -independent mechanisms. Recently, it has been demonstrated that the protein tyrosine kinase (PTK)-dependent signal transduction pathway is an important aldosterone-independent regulatory mechanism that mediates the effect of altered K intake on K secretion. A low-K intake stimulates PTK activity, which leads to increase in phosphorylation of cloned inwardly rectifying renal K (ROMK) channels, whereas a high-K intake has the opposite effect. Stimulation of tyrosine phosphorylation also suppresses K secretion in principal cell by facilitating the internalization of apical K channels in the collecting duct.
Learning Mechanisms in Addiction: Synaptic Plasticity in the Ventral Tegmental Area as a Result of Exposure to Drugs of Abuse
Authors: Kauer Julie A.
Published: February 2004

▪ Abstract  One of the central questions in neurobiology is how experience modifies neural function, and how changes in the nervous system permit an animal to adapt its behavior to a changing environment. Learning and adaptation to a host of different environmental stimuli exemplify processes we know must alter the nervous system because the behavioral output changes after experience. Alterations in behavior after exposure to addictive drugs are a striking example of chemical alterations of nervous system function producing long-lasting changes in behavior. The alterations produced in the central nervous system (CNS) by addictive drugs are of interest because of their relationship to human substance abuse but also because these CNS alterations produce dramatic, easily observed alterations in behavior in response to discrete stimuli. Considerable study has been given to behavioral and biochemical correlates of addiction over the past 50 or more years; however, our understanding of the cellular physiological responses of affected CNS neurons is in its infancy. This review focuses on alterations in cellular and synaptic physiology in the ventral tegmental area (VTA) in response to addictive drugs.
Myosin-1c, the Hair Cell's Adaptation Motor
Authors: Gillespie Peter G. , Cyr Janet L.
Published: February 2004

▪ Abstract  Given their prominent actin-rich subcellular specializations, it is no surprise that mechanosensitive hair cells of the inner ear exploit myosin molecules—the only known actin-dependent molecular motors—to carry out exotic but essential tasks. Recent experiments have confirmed that an unconventional myosin isozyme, myosin-1c, is a component of the hair cell's adaptation-motor complex. This complex carries out slow adaptation, provides tension to sensitize transduction channels, and may participate in assembly of the transduction apparatus. This review focuses on the detailed operation of the adaptation motor and the functional consequences of the incorporation of this specific myosin isozyme into the motor complex.
Localization of Voltage-Gated Ion Channels IN Mammalian Brain
Authors: Trimmer James S. , Rhodes Kenneth J.
Published: February 2004

▪ Abstract  The intrinsic electrical properties of neurons are shaped in large part by the action of voltage-gated ion channels. Molecular cloning studies have revealed a large family of ion channel genes, many of which are expressed in mammalian brain. Much recent effort has focused on determining the contribution of the protein products of these genes to neuronal function. This requires knowledge of the abundance and distribution of the constituent subunits of the channels in specific mammalian central neurons. Here we review progress made in recent studies aimed at localizing specific ion channel subunits using in situ hybridization and immunohistochemistry. We then discuss the implications of these results in terms of neuronal physiology and neuronal mechanisms underlying the observed patterns of expression.
Field Physiology: Physiological Insights from Animals in Nature
Authors: Costa Daniel P. , Sinervo Barry
Published: February 2004

▪ Abstract  Whereas comparative physiology documents the range of physiological variation across a range of organisms, field physiology provides insight into the actual mechanisms an organism employs to maintain homeostasis in its everyday life. This requires an understanding of an organism's natural history and is prerequisite to developing hypotheses about physiological mechanisms. This review focuses on a few areas of field physiology that exemplify how the underlying physiology could not have been understood without appropriate field measurements. The examples we have chosen highlight the methods and inference afforded by an application of this physiological analysis to organismal function in nature, often in extreme environments. The specific areas examined are diving physiology, the thermal physiology of large endothermic fishes, reproductive physiology of air breathing vertebrates, and endocrine physiology of reproductive homeostasis. These areas form a bridge from physiological ecology to evolutionary ecology.

All our examples revolve around the central issue of physiological limits as they apply to organismal homeostasis. We view this theme as the cornerstone of physiological analysis and supply a number of paradigms on homeostasis that have been tested in the context of field physiology.
Biochemical Indicators of Stress and Metabolism: Applications for Marine Ecological Studies
Authors: Dahlhoff Elizabeth P.
Published: February 2004

▪ Abstract  Studies investigating the effects of temperature, food availability, or other physical factors on the physiology of marine animals have led to the development of biochemical indicators of growth rate, metabolic condition, and physiological stress. Measurements of metabolic enzyme activity and RNA/DNA have been especially valuable as indicators of condition in studies of marine invertebrates and fishes, groups for which accurate determination of field metabolic rates is difficult. Properly calibrated and applied, biochemical indicators have been successfully used in studies of rocky intertidal ecology, where two decades of experimentation have generated rigorous, testable models for determining the relative influences of biotic and abiotic factors on species distribution, abundance, and interaction. Biochemical indicators of condition and metabolic activity (metabolic enzymes, RNA/DNA) have been used to test nutrient-productivity models by demonstrating tight linkages between nearshore oceanographic processes (such as upwelling) and benthic rocky intertidal ecosystems. Indices of condition and heat stress (heat shock proteins, or Hsps) have begun to be used to test environmental stress models by comparing condition, activity, and Hsp expression of key rocky intertidal predator and prey species. Using biochemical indicators of condition and stress in natural systems holds great promise for understanding mechanisms by which organisms respond to rapid environmental change.
Metabolic Rate and Body Temperature Reduction During Hibernation and Daily Torpor
Authors: Geiser Fritz
Published: February 2004

▪ Abstract  Although it is well established that during periods of torpor heterothermic mammals and birds can reduce metabolic rates (MR) substantially, the mechanisms causing the reduction of MR remain a controversial subject. The comparative analysis provided here suggests that MR reduction depends on patterns of torpor used, the state of torpor, and body mass. Daily heterotherms, which are species that enter daily torpor exclusively, appear to rely mostly on the fall of body temperature (Tb) for MR reduction, perhaps with the exception of very small species and at high torpor Tb, where some metabolic inhibition may be used. In contrast, hibernators (species capable of prolonged torpor bouts) rely extensively on metabolic inhibition, in addition to Tbeffects, to reduce MR to a fraction of that observed in daily heterotherms. In small hibernators, metabolic inhibition and the large fall of Tbare employed to maximize energy conservation, whereas in large hibernators, metabolic inhibition appears to be employed to facilitate MR and Tbreduction at torpor onset. Over the ambient temperature (Ta) range where torpid heterotherms are thermo-conforming, the Tb-Tadifferential is more or less constant despite a decline of MR with Ta; however, in thermo-regulating torpid individuals, the Tb-Tadifferential is maintained by a proportional increase of MR as during normothermia, albeit at a lower Tb. Thermal conductance in most torpid thermo-regulating individuals is similar to that in normothermic individuals despite the substantially lower MR in the former. However, conductance is low when deeply torpid animals are thermo-conforming probably because of peripheral vasoconstriction.
Sleep and Circadian Rhythms in Mammalian Torpor
Authors: Heller H. Craig , Ruby Norman F.
Published: February 2004

▪ Abstract  Sleep and circadian rhythms are the primary determinants of arousal state, and torpor is the most extreme state change that occurs in mammals. The view that torpor is an evolutionary extension of sleep is supported by electrophysiological studies. However, comparisons of factors that influence the expression of sleep and torpor uncover significant differences. Deep sleep immediately following torpor suggests that torpor is functionally a period of sleep deprivation. Recent studies that employ post-torpor sleep deprivation, however, show that the post-torpor intense sleep is not homeostatically regulated, but might be a reflection of synaptic loss and replacement. The circadian system regulates sleep expression in euthermic mammals in such a way that would appear to preclude multiday bouts of torpor. Indeed, the circadian system is robust in animals that show shallow torpor, but its activity in hibernators is at least damped if not absent. There is good evidence from some species, however, that the circadian system plays important roles in the timing of bouts of torpor.
Genetically Engineered Mouse Models for Lung Cancer
Authors: Kwak I. , Tsai S.Y. , DeMayo F.J.
Published: February 2004

▪ Abstract  The lung is a complex organ consisting of numerous cell types that function to ensure sufficient gas exchange to oxygenate the blood. In order to accomplish this function, the lung must be exposed to the external environment and at the same time maintain a homeostatic balance between its function in gas exchange and the maintenance of inflammatory balance. During the past two decades, as molecular methodologies have evolved with the sequencing of entire genomes, the use of in vivo models to elucidate the molecular mechanisms involved in pulmonary physiology and disease have increased. The mouse has emerged as a potent model to investigate pulmonary physiology due to the explosion in molecular methods that now allow for the developmental and tissue-specific regulation of gene transcription. Initial efforts to manipulate gene expression in the mouse genome resulted in the generation of transgenic mice characterized by the constitutive expression of a specific gene and knockout mice characterized by the ablation of a specific gene. The utility of these original mouse models was limited, in many cases, by phenotypes resulting in embryonic or neonatal lethality that prevented analysis of the impact of the genetic manipulation on pulmonary biology. Second-generation transgenic mouse models employ multiple strategies that can either activate or silence gene expression thereby providing extensive temporal and spatial control of the experimental parameters of gene expression. These highly regulated mouse models are intended to serve as a foundation for further investigation of the molecular basis of human disease such as tumorigenesis. This review describes the principles, progress, and application of systems that are currently employed in the conditional regulation of gene expression in the investigation of lung cancer.
Alterations in SP-B and SP-C Expression in Neonatal Lung Disease
Authors: Nogee Lawrence M.
Published: February 2004

▪ Abstract  The hydrophobic surfactant proteins, SP-B and SP-C, have important roles in surfactant function. The importance of these proteins in normal lung function is highlighted by the lung diseases associated with abnormalities in their expression. Mutations in the gene encoding SP-B result in severe, fatal neonatal lung disease, and mutations in the gene encoding SP-C are associated with chronic interstitial lung diseases in newborns, older children, and adults. This work reviews the current state of knowledge concerning the lung diseases associated with mutations in the SP-B and SP-C genes, and the potential roles of abnormal SP-B and SP-C expression and genetic variation in these genes in other lung diseases.
Epithelial-Mesenchymal Interactions in the Developing Lung
Authors: Shannon John M. , Hyatt Brian A.
Published: February 2004

▪ Abstract  Classical experiments in embryology have shown that normal growth, morphogenetic patterning, and cellular differentiation in the developing lung depend on interactive signaling between the endodermal epithelium and mesenchyme derived from splanchnic mesoderm. These interactions are mediated by a myriad of diffusible factors that are precisely regulated in their temporal and spatial expression. In this review we first describe factors regulating formation of the embryonic foregut. We then discuss the experiments demonstrating the importance of tissue interactions in lung patterning and differentiation. Finally, we detail the roles that a few key signaling systems—fibroblast growth factors and their receptors, sonic hedgehog and Gli genes, Wnt genes and β-catenin, and BMP4—play as mediators of epithelial-mesenchymal interactions in the developing lung.
Myocardial Aging and Senescence: Where Have the Stem Cells Gone?
Authors: Sussman Mark A. , Anversa Piero
Published: February 2004

▪ Abstract  Heart failure remains a leading cause of hospital admissions and mortality in the elderly, and current interventional approaches often fail to treat the underlying cause of pathogenesis. Preservation of structure and function in the aging myocardium is most likely to be successful via ongoing cellular repair and replacement, as well as survival of existing cardiomyocytes that generate contractile force. Research has led to a paradigm shift driven by application of stem cells to generate cardiovascular cell lineages. Early controversial findings of pluripotent precursors adopting cardiac phenotypes are now widely accepted, and current debate centers upon the efficiency of progenitor cell incorporation into the myocardium. Much work remains to be done in determining the relevant progenitor cell population and optimizing conditions for efficient differentiation and integration. Significant implications exist for treatment of pathologically damaged or aging myocardium since future interventional approaches will capitalize upon the use of cardiac stem cells as therapeutic reagents.