Showing papers by "University of Notre Dame published in 2004"
TL;DR: This work states that rapid advances in network biology indicate that cellular networks are governed by universal laws and offer a new conceptual framework that could potentially revolutionize the view of biology and disease pathologies in the twenty-first century.
Abstract: A key aim of postgenomic biomedical research is to systematically catalogue all molecules and their interactions within a living cell. There is a clear need to understand how these molecules and the interactions between them determine the function of this enormously complex machinery, both in isolation and when surrounded by other cells. Rapid advances in network biology indicate that cellular networks are governed by universal laws and offer a new conceptual framework that could potentially revolutionize our view of biology and disease pathologies in the twenty-first century.
7,475 citations
TL;DR: The size-dependent shift in the apparent Fermi level of the TiO(2)-Au composite shows the ability of Au nanoparticles to influence the energetics by improving the photoinduced charge separation.
Abstract: Photoexcited semiconductor nanoparticles undergo charge equilibration when they are in contact with metal nanoparticles. Such a charge distribution has direct influence in dictating the energetics of the composite by shifting the Fermi level to more negative potentials. The transfer of electrons to Au nanoparticles has now been probed by exciting TiO2 nanoparticles under steady-state and laser pulse excitation. Equilibration with the C60/C60- redox couple provides a means to determine the apparent Fermi level of the TiO2−Au composite system. The size-dependent shift in the apparent Fermi level of the TiO2−Au composite (20 mV for 8-nm diameter and 40 mV for 5-nm and 60 mV for 3-nm gold nanoparticles) shows the ability of Au nanoparticles to influence the energetics by improving the photoinduced charge separation. Isolation of individual charge-transfer steps from UV-excited TiO2 → Au → C60 has provided mechanistic and kinetic information on the role of metal in semiconductor-assisted photocatalysis and siz...
1,896 citations
TL;DR: In this paper, the authors present density as a function of temperature, melting temperatures, glass transition temperatures, decomposition temperatures, and heat capacities for 13 ionic liquids, including 1-butyl-3-methylimidazolium trifluoromethanesulfonate.
Abstract: Ionic liquids (ILs) are salts that are liquid at low temperatures, usually including the region around room temperature. They are under intense investigation, especially as replacement solvents for reactions and separations, since they exhibit negligible vapor pressure and would not, therefore, contribute to air pollution. Clearly, basic thermophysical properties are vital for design and evaluation for these applications. We present density as a function of temperature, melting temperatures, glass-transition temperatures, decomposition temperatures, and heat capacities as a function of temperature for a series of 13 of the popular imidazolium-based ILs. The ionic liquids investigated here are 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium tris(trifluoromethylsul...
1,438 citations
TL;DR: Experimental and molecular modeling studies are conducted to investigate the underlying mechanisms for the high solubility of CO2 in imidazolium-based ionic liquids and it is found that the bis(trifluoromethylsulfonyl)imide anion has the greatest affinity for CO2, while there is little difference in CO2solubility between ionsic liquids having the tetrafluoroborate or hexafluorophosphate anion.
Abstract: Experimental and molecular modeling studies are conducted to investigate the underlying mechanisms for the high solubility of CO2 in imidazolium-based ionic liquids. CO2 absorption isotherms at 10, 25, and 50 °C are reported for six different ionic liquids formed by pairing three different anions with two cations that differ only in the nature of the “acidic” site at the 2-position on the imidazolium ring. Molecular dynamics simulations of these two cations paired with hexafluorophosphate in the pure state and mixed with CO2 are also described. Both the experimental and the simulation results indicate that the anion has the greatest impact on the solubility of CO2. Experimentally, it is found that the bis(trifluoromethylsulfonyl)imide anion has the greatest affinity for CO2, while there is little difference in CO2 solubility between ionic liquids having the tetrafluoroborate or hexafluorophosphate anion. The simulations show strong organization of CO2 about hexafluorophosphate anions, but only small diffe...
1,352 citations
TL;DR: Phylogenetic analysis of bacterial HDAC relatives suggests that all three HDAC classes precede the evolution of histone proteins and raises the possibility that the primary activity of some "histone deacetylase" enzymes is directed against non-histone substrates.
1,342 citations
TL;DR: In this paper, the authors describe a model of earnings and earnings growth and demonstrate how this model may be used to obtain estimates of the expected rate of return on equity capital, and compare these estimates with estimates of expected rates of return implied by commonly used heuristics, such as the PEG ratio and the PE ratio.
Abstract: I describe a model of earnings and earnings growth and I demonstrate how this model may be used to obtain estimates of the expected rate of return on equity capital. These estimates are compared with estimates of the expected rate of return implied by commonly used heuristics—viz., the PEG ratio and the PE ratio. Proponents of the PEG ratio (which is the price‐earnings [PE] ratio divided by the short‐term earnings growth rate) argue that this ratio takes account of differences in short‐run earnings growth, providing a ranking that is superior to the ranking based on PE ratios. But even though the PEG ratio may provide an improvement over the PE ratio, it is arguably still too simplistic because it implicitly assumes that the short‐run growth forecast also captures the long‐run future. I provide a means of simultaneously estimating the expected rate of return and the rate of change in abnormal growth in earnings beyond the (short) forecast horizon—thereby refining the PEG ratio ranking. The method may also...
1,044 citations
TL;DR: While the elastic modulus and yield strains for trabecular tissue are just slightly lower than those of cortical tissue, because of the cumulative effect of these differences, tissue strength is about 25% greater for cortical bone.
970 citations
TL;DR: This paper describes a project to create a novel design and simulation tool for quantum-dot cellular automata (QCA), namely QCADesigner, which has already been used to design full-adders, barrel shifters, random-access memories, etc.
Abstract: This paper describes a project to create a novel design and simulation tool for quantum-dot cellular automata (QCA), namely QCADesigner. QCA logic and circuit designers require a rapid and accurate simulation and design layout tool to determine the functionality of QCA circuits. QCADesigner gives the designer the ability to quickly layout a QCA design by providing an extensive set of CAD tools. As well, several simulation engines facilitate rapid and accurate simulation. This tool has already been used to design full-adders, barrel shifters, random-access memories, etc. These verified layouts provide motivation to continue efforts toward a final implementation of QCA circuits.
827 citations
TL;DR: In this article, the authors presented 2.5-30 mum spectra from the Short-Wavelength Spectrometer of the Infrared Space Observatory for a total of 23 sources, including embedded young stellar objects spanning a wide range of mass and luminosity.
Abstract: We present 2.5-30 mum spectra from the Short-Wavelength Spectrometer of the Infrared Space Observatory for a total of 23 sources. The sources include embedded young stellar objects spanning a wide range of mass and luminosity, together with field stars sampling quiescent dark clouds and the diffuse interstellar medium. Expanding on results of previous studies, we use these spectra to investigate ice composition as a function of environment. The spectra reveal an extremely rich set of absorption features attributed to simple molecules in the ices. We discuss the observed properties of these absorption features and review their assignments. Among the species securely identified are H2O, CO, CO2, CH3OH, and CH4. Likely identified species include OCS, H2CO, and HCOOH. There is also evidence for NH3 and OCN- ice features, but these identifications are more controversial. Features that continue to defy identification include the 3.3-3.7 mum "ice band wing'' and the bulk of the 6.8 mum feature. In addition, we find evidence for excess absorption at 6.0 mum that cannot be attributed to H2O ice. We examine the degree of intercorrelation of the 6.8 mum, 4.62 mum ("XCN'') and 6.0 mum (excess) features. Our results are consistent with the interpretation of the 6.8 and 4.62 mum features as due to NH4+ and OCN- ions, respectively, though alternative explanations cannot currently be ruled out. We find that the optical depth correlations are dependent on the profile of the 6.8 mum feature but not on the mass of the YSO nor the ice temperature along the line of sight. We discuss the implications for our current understanding of ice processing. We briefly discuss the composition, origin, and evolution of interstellar ices.
785 citations
Iowa State University1, University of Georgia2, Stanford University3, Ludwig Institute for Cancer Research4, University of California, Berkeley5, Duke University6, University of California, San Diego7, University of Notre Dame8, University of Tokyo9, Max Planck Society10, University of Colorado Boulder11, Harvard University12, Colorado State University13, Indiana University14, Ludwig Maximilian University of Munich15, University of California, Davis16, University of California, San Francisco17, University of Washington18
TL;DR: A standardized kinesin nomenclature based on 14 family designations is set forth, which unifies all previous phylogenies and nomenClature proposals, while allowing individual sequence names to remain the same, and for expansion to occur as new sequences are discovered.
Abstract: In recent years the kinesin superfamily has become so large that several different naming schemes have emerged, leading to confusion and miscommunication. Here, we set forth a standardized kinesin nomenclature based on 14 family designations. The scheme unifies all previous phylogenies and nomenclature proposals, while allowing individual sequence names to remain the same, and for expansion to occur as new sequences are discovered.
735 citations
TL;DR: This paper examined attitudes related to feminism and gender equality by evaluating the trends in, and determinants of women and men's attitudes from 1974 to 1998, finding that attitudes have continued to liberalize and converge with the exception of abortion attitudes.
Abstract: This article examines attitudes related to feminism and gender equality by evaluating the trends in, and determinants of women and men's attitudes from 1974 to 1998. Past accounts suggest two clusters of explanations based on interests and exposure. Using these, we examine opinions on abortion, sexual behavior, public sphere gender roles, and family responsibilities. We find that attitudes have continued to liberalize and converge with the exception of abortion attitudes. The determinants of feminist opinion vary across domains, but have been largely stable. While not identical, the predictors of men and women's opinions are similar The results suggest the need for more attention to the mechanisms underlying the production of feminist opinions and theoretical integration of both interests and exposure in a dynamic process.
TL;DR: A class of algebraically structured quasi-cyclic low-density parity-check (LDPC) codes and their convolutional counterparts is presented and bounds on the girth and minimum distance of the codes are found, and several possible encoding techniques are described.
Abstract: A class of algebraically structured quasi-cyclic (QC) low-density parity-check (LDPC) codes and their convolutional counterparts is presented. The QC codes are described by sparse parity-check matrices comprised of blocks of circulant matrices. The sparse parity-check representation allows for practical graph-based iterative message-passing decoding. Based on the algebraic structure, bounds on the girth and minimum distance of the codes are found, and several possible encoding techniques are described. The performance of the QC LDPC block codes compares favorably with that of randomly constructed LDPC codes for short to moderate block lengths. The performance of the LDPC convolutional codes is superior to that of the QC codes on which they are based; this performance is the limiting performance obtained by increasing the circulant size of the base QC code. Finally, a continuous decoding procedure for the LDPC convolutional codes is described.
TL;DR: A flux balance analysis of the metabolism of Escherichia coli strain MG1655 shows that network use is highly uneven, which probably represents a universal feature of metabolic activity in all cells, with potential implications for metabolic engineering.
Abstract: Cellular metabolism, the integrated interconversion of thousands of metabolic substrates through enzyme-catalysed biochemical reactions, is the most investigated complex intracellular web of molecular interactions. Although the topological organization of individual reactions into metabolic networks is well understood, the principles that govern their global functional use under different growth conditions raise many unanswered questions. By implementing a flux balance analysis of the metabolism of Escherichia coli strain MG1655, here we show that network use is highly uneven. Whereas most metabolic reactions have low fluxes, the overall activity of the metabolism is dominated by several reactions with very high fluxes. E. coli responds to changes in growth conditions by reorganizing the rates of selected fluxes predominantly within this high-flux backbone. This behaviour probably represents a universal feature of metabolic activity in all cells, with potential implications for metabolic engineering.
TL;DR: In this article, a generic airfoil shape (NACA 663-018) was used because of its documented leading-edge stall characteristics, and it was instrumented for surface pressure measurements that were used to calculate lift coefficients.
Abstract: This work involves the documentation and control of leading-edge flow separation that occurs over an airfoil at high angles of attack, well above stall. A generic airfoil shape (NACA 663-018) was used because of its documented leading-edge stall characteristics. It was instrumented for surface-pressure measurements that were used to calculate lift coefficients. Mean-velocity profiles downstream of the airfoil were used to determine the drag coefficient. In addition to these, smoke streakline flow visualization was used to document the state of flow separation. The airfoil was operated over a range of freestream speeds from 10 to 30 m/s, giving chord Reynolds numbers from 77 × 10 3 to 333 × 10 3 .T wo types of plasma actuator designs were investigated. The first produced a spanwise array of streamwise vortices. The second produced a two-dimensional jet in the flow direction along the surface of the airfoil. The plasma actuators were found to lead to reattachment for angles of attack that were 8 deg past the stall angle (the highest investigated). This was accompanied by a full pressure recovery and up to a 400% increase in the lift-to-drag ratio.
TL;DR: This work compares four available databases that approximate the protein interaction network of the yeast, Saccharomyces cerevisiae, aiming to uncover the network's generic large‐scale properties and the impact of the proteins' function and cellular localization on the network topology.
Abstract: The elucidation of the cell’s large-scale organization is a primary challenge for post-genomic biology, and understanding the structure of protein interaction networks offers an important starting point for such studies. We compare four available databases that approximate the protein interaction network of the yeast, Saccharomyces cerevisiae, aiming to uncover the network’s generic large-scale properties and the impact of the proteins’ function and cellular localization on the network topology. We show how each database supports a scale-free, topology with hierarchical modularity, indicating that these features represent a robust and generic property of the protein interactions network. We also find strong correlations between the network’s structure and the functional role and subcellular localization of its protein constituents, concluding that most functional and/or localization classes appear as relatively segregated subnetworks of the full protein interaction network. The uncovered systematic differences between the four protein interaction databases reflect their relative coverage for different functional and localization classes and provide a guide for their utility in various bioinformatics studies.
TL;DR: A method which first transcribes an optimal control problem into an equivalent problem parameterized by the switching instants and then obtains the values of the derivatives based on the solution of a two point boundary value differential algebraic equation formed by the state, costate, stationarity equations, the boundary and continuity conditions, along with their differentiations is developed.
Abstract: This paper presents a new approach for solving optimal control problems for switched systems. We focus on problems in which a prespecified sequence of active subsystems is given. For such problems, we need to seek both the optimal switching instants and the optimal continuous inputs. In order to search for the optimal switching instants, the derivatives of the optimal cost with respect to the switching instants need to be known. The most important contribution of the paper is a method which first transcribes an optimal control problem into an equivalent problem parameterized by the switching instants and then obtains the values of the derivatives based on the solution of a two point boundary value differential algebraic equation formed by the state, costate, stationarity equations, the boundary and continuity conditions, along with their differentiations. This method is applied to general switched linear quadratic problems and an efficient method based on the solution of an initial value ordinary differential equation is developed. An extension of the method is also applied to problems with internally forced switching. Examples are shown to illustrate the results in the paper.
TL;DR: The stability of MB-NCSs is studied when the controller/actuator is updated with the sensor information at nonconstant time intervals and sufficient conditions for Lyapunov stability are derived.
Abstract: In model-based networked control systems (MB-NCSs), an explicit model of the plant is used to produce an estimate of the plant state behavior between transmission times. In this paper, the stability of MB-NCSs is studied when the controller/actuator is updated with the sensor information at nonconstant time intervals. Networked control systems with transmission times that are varying either within a time interval or are driven by a stochastic process with identically independently distributed and Markov-chain driven transmission times are studied. Sufficient conditions for Lyapunov stability are derived. For stochastically modeled transmission times almost sure stability and mean-square sufficient conditions for stability are introduced.
TL;DR: In this article, the authors propose that autonomy support can be manifested in the classroom in at least three distinct ways: organizational autonomy support (e.g., allowing students some decision-making role in terms of classroom management issues), procedural autonomy support, and cognitive autonomy support.
Abstract: In addition to classroom activities, teachers provide personal and instructional supports meant to facilitate the developing sense of student autonomy. In this article, we offer a way of thinking about autonomy-supportive practices that suggests that such practices can be distinguished at a featural level and that different practices may in fact have different outcomes in terms of student classroom behavior. Specifically, we propose that autonomy support can be manifested in the classroom in at least 3 distinct ways: organizational autonomy support (e.g., allowing students some decision-making role in terms of classroom management issues), procedural autonomy support (e.g., offering students choices about the use of different media to present ideas), and cognitive autonomy support (e.g., affording opportunities for students to evaluate work from a self-referent standard). We offer vignettes of teachers in their classes to illustrate our proposition that autonomy support may be carried out on several plane...
TL;DR: Underpowered studies persist in the psychological literature and the effects on efforts to create a cumulative science are examined and the "curse of multiplicities" plays a central role.
Abstract: Underpowered studies persist in the psychological literature. This article examines reasons for their persistence and the effects on efforts to create a cumulative science. The "curse of multiplicities" plays a central role in the presentation. Most psychologists realize that testing multiple hypotheses in a single study affects the Type I error rate, but corresponding implications for power have largely been ignored. The presence of multiple hypothesis tests leads to 3 different conceptualizations of power. Implications of these 3 conceptualizations are discussed from the perspective of the individual researcher and from the perspective of developing a coherent literature. Supplementing significance tests with effect size measures and confidence intervals is shown to address some but not necessarily all problems associated with multiple testing.
University of Hawaii1, European Southern Observatory2, Harvard University3, University of California, Berkeley4, Pontifical Catholic University of Chile5, University of Notre Dame6, Goddard Space Flight Center7, University of Washington8, Space Telescope Science Institute9, Australian National University10
TL;DR: In this article, photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range of z = 0.34-1.03, nine of which are unambiguously classified as Type Ia.
Abstract: We present photometric and spectroscopic observations of 23 high-redshift supernovae (SNe) spanning a range of z = 0.34-1.03, nine of which are unambiguously classified as Type Ia. These SNe were discovered during the IfA Deep Survey, which began in 2001 September and observed a total of 2.5 deg2 to a depth of approximately m ? 25-26 in RIZ over 9-17 visits, typically every 1-3 weeks for nearly 5 months, with additional observations continuing until 2002 April. We give a brief description of the survey motivations, observational strategy, and reduction process. This sample of 23 high-redshift SNe includes 15 at z ? 0.7, doubling the published number of objects at these redshifts, and indicates that the evidence for acceleration of the universe is not due to a systematic effect proportional to redshift. In combination with the recent compilation of Tonry et al. (2003), we calculate cosmological parameter density contours that are consistent with the flat universe indicated by the cosmic microwave background (Spergel et al. 2003). Adopting the constraint that ?total = 1.0, we obtain best-fit values of (?m,??) = (0.33, 0.67) using 22 SNe from this survey augmented by the literature compilation. We show that using the empty-beam model for gravitational lensing does not eliminate the need for ?? > 0. Experience from this survey indicates great potential for similar large-scale surveys while also revealing the limitations of performing surveys for z > 1 SNe from the ground.
TL;DR: In this paper, a new paradigm for tuning the optical properties of gold nanorods by organizing them longitudinally, using thioalkylcarboxylic acid based bifunctional molecules is reported.
Abstract: We report a new paradigm for tuning the optical properties of gold nanorods by organizing them longitudinally, using thioalkylcarboxylic acid based bifunctional molecules. The rationale behind the selection of the bifunctional molecule is based on the fact that the thiol group binds to the ends of the nanorods, which further assembles in a longitudinal fashion through cooperative hydrogen bonding between the carboxylic groups. A generalized procedure for uniaxial plasmon coupling through longitudinal self-assembly of Au nanorods, initially to dimers and further to linear assemblies, is presented. Uniaxial modulation of interplasmon coupling through stepwise self-assembly of Au nanorods will have application in nanoelectronics and plasmonics.
TL;DR: In this paper, an alternative class of discrete Wigner functions, in which the field of real numbers that labels the axes of continuous phase space is replaced by a finite field having $N$ elements.
Abstract: The original Wigner function provides a way of representing in phase space the quantum states of systems with continuous degrees of freedom. Wigner functions have also been developed for discrete quantum systems, one popular version being defined on a $2N\ifmmode\times\else\texttimes\fi{}2N$ discrete phase space for a system with $N$ orthogonal states. Here we investigate an alternative class of discrete Wigner functions, in which the field of real numbers that labels the axes of continuous phase space is replaced by a finite field having $N$ elements. There exists such a field if and only if $N$ is a power of a prime; so our formulation can be applied directly only to systems for which the state-space dimension takes such a value. Though this condition may seem limiting, we note that any quantum computer based on qubits meets the condition and can thus be accommodated within our scheme. The geometry of our $N\ifmmode\times\else\texttimes\fi{}N$ phase space also leads naturally to a method of constructing a complete set of $N+1$ mutually unbiased bases for the state space.
TL;DR: In this article, the authors reported the observation of the X(3872) in the J/psipi(+)pi(-) channel with decaying to mu(+)mu(-), in p (p) over bar collisions at roots=1.96 TeV.
Abstract: We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in p (p) over bar collisions at roots=1.96 TeV. Using approximately 230 pb(-1) of data collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.
TL;DR: In this paper, a short-duration (~7 days) low-amplitude deviation in the light curve due to a single-lens profile was observed in both the MOA (Microlensing Observations in Astrophysics) and OGLE (Optical Gravitational Lensing Experiment) survey observations.
Abstract: We present observations of the unusual microlensing event OGLE 2003-BLG-235/MOA 2003-BLG-53. In this event, a short-duration (~7 days) low-amplitude deviation in the light curve due to a single-lens profile was observed in both the MOA (Microlensing Observations in Astrophysics) and OGLE (Optical Gravitational Lensing Experiment) survey observations. We find that the observed features of the light curve can only be reproduced using a binary microlensing model with an extreme (planetary) mass ratio of 0.0039 for the lensing system. If the lens system comprises a main-sequence primary, we infer that the secondary is a planet of about 1.5 Jupiter masses with an orbital radius of ~3 AU.
TL;DR: In this paper, the impact of different factors on the phase behavior of imidazolium-based ionic liquids with alcohols was studied, and all systems examined showed upper critical solution temperature (UCST) behavior, with low solubility of the ionic liquid in the alcohol.
Abstract: Ionic liquids have been suggested as replacement solvents in reactions and separations since they have negligible vapor pressure; thus, they would reduce fugitive emissions that are common when organic solvents are used in these applications. To fully utilize ionic liquids in reactions and separations, a fundamental understanding of the factors that govern the phase behavior of ionic liquids with other common liquids is necessary. In this work, we present a systematic study of the impact of different factors on the phase behavior of imidazolium-based ionic liquids with alcohols. All systems examined showed upper critical solution temperature (UCST) behavior, with low solubility of the ionic liquid in the alcohol and high solubility of the alcohol in the ionic liquid. An increase in the alkyl chain length of the alcohol resulted in an increase in the UCST. Branching of the alcohol resulted in a higher solubility of the alcohol in the ionic-liquid-rich phase. By increasing the alkyl chain length on the cati...
TL;DR: The authors examined the effect of pro-forma earnings disclosures on the judgments of analysts and non-professionals on the stock price of a company and found that nonprofessional investors who received an earnings announcement that contained both pro forma and GAAP disclosures assessed a higher stock price than did professional investors that received an announcement containing only GAAP disclosure.
Abstract: This paper presents an experiment that examines the effect of pro forma earnings disclosures on the judgments of analysts (i.e., more sophisticated investors) and nonprofessional (i.e., less sophisticated) investors. In the experiment, participants developed stock price assessments after reviewing background financial information and a current earnings announcement for a company. The earnings announcement was manipulated to report only GAAP earnings in one condition and both pro forma and GAAP earnings in the other condition. Consistent with empirical evidence, the pro forma earnings in our experiment exceeded GAAP earnings. The results indicate that nonprofessional investors who received an earnings announcement that contained both pro forma and GAAP disclosures assessed a higher stock price than did nonprofessionals who received an announcement containing only GAAP disclosures. Financial analysts' stock price judgments were not affected by the pro forma disclosures. Followup analyses suggest that analys...
TL;DR: It is found that reducing the per–ship–visit chance of causing invasion is more effective in reducing the rate of biotic homogenization than eliminating key ports that are the epicentres for global spread.
Abstract: Biological invasions from ballast water are a severe environmental threat and exceedingly costly to society. We identify global hot spots of invasion based on worldwide patterns of ship traffic. We then estimate the rate of port-to-port invasion using gravity models for spatial interactions, and we identify bottlenecks to the regional exchange of species using the Ford-Fulkerson algorithm for network flows. Finally, using stochastic simulations of different strategies for controlling ballast-water introductions, we find that reducing the per-ship-visit chance of causing invasion is more effective in reducing the rate of biotic homogenization than eliminating key ports that are the epicentres for global spread.
TL;DR: In this paper, the authors present multizone models of Type I X-ray bursts that use an adaptive nuclear reaction network of unprecedented size, up to 1300 isotopes, for energy generation and include the most recent measurements and estimates of critical nuclear physics.
Abstract: Multizone models of Type I X-ray bursts are presented that use an adaptive nuclear reaction network of unprecedented size, up to 1300 isotopes, for energy generation and include the most recent measurements and estimates of critical nuclear physics. Convection and radiation transport are included in calculations that carefully follow the changing composition in the accreted layer, both during the bursts themselves and in their ashes. Sequences of bursts, up to 15 in one case, are followed for two choices of accretion rate and metallicity, up to the point at which a limit cycle equilibrium is established. For (M)over dot=1.75x10(-9) M-circle dot yr(-1) (and (M)over dot=3.5x10(-10) M-circle dot yr(-1), for low metallicity), combined hydrogen-helium flashes occur. These bursts have light curves with slow rise times (seconds) and long tails. The rise times, shapes, and tails of these light curves are sensitive to the efficiency of nuclear burning at various waiting points along the rp-process path, and these sensitivities are explored. Each displays ``compositional inertia`` in that its properties are sensitive to the fact that accretion occurs onto the ashes of previous bursts that contain leftover hydrogen, helium, and CNO nuclei. This acts to reduce the sensitivity of burst properties to metallicity. Only the first anomalous burst in one model produces nuclei as heavy as A=100. For the present choice of nuclear physics and accretion rates, other bursts and models make chiefly nuclei with Aapproximate to64. The amount of carbon remaining after hydrogen-helium bursts is typically less than or similar to1 and decreases further as the ashes are periodically heated by subsequent bursts. For (M)over dot=3.5x10(-10) M-circle dot yr(-1) and solar metallicity, bursts are ignited in a hydrogen-free helium layer. At the base of this layer, up to 90 to carbon prior to the unstable ignition of the helium shell. These helium-ignited bursts have (1) briefer, brighter light curves with shorter tails, (2) very rapid rise times (>0.1 s), and (3) ashes lighter than the iron group.
TL;DR: In this paper, a reproducible way to obtain films of varying amounts of single-walled carbon nanotubes (SWCNTs) on electrode surfaces using electrophoretic deposition is presented.
Abstract: We show here, for the first time, a reproducible way to obtain films of varying amounts of single-walled carbon nanotubes (SWCNTs) on electrode surfaces using electrophoretic deposition. We deposit these nanotubes in a facile manner on an optically transparent electrode (OTE) and investigate its performance as an electrode material in the presence of platinum for methanol oxidation and oxygen reduction. Our focus here is on the deposition of the SWCNT on the electrodes, the characterization of the nanotubes on the electrode surface, and the cyclic voltammetry of methanol oxidation and oxygen reduction using these nanostructured carbon electrodes with platinum electrodeposited on them. The nanotubes retain their structure on the electrode surface, and we can obtain electrodes with relatively thick films of the CNTs. The high surface area and porosity of these films enable us to use relatively small amounts of platinum and yet obtain excellent currents. We see a remarkable enhancement in methanol oxidation ...