Showing papers by "Arizona State University published in 2003"

Reticular synthesis and the design of new materials

Abstract: The long-standing challenge of designing and constructing new crystalline solid-state materials from molecular building blocks is just beginning to be addressed with success. A conceptual approach that requires the use of secondary building units to direct the assembly of ordered frameworks epitomizes this process: we call this approach reticular synthesis. This chemistry has yielded materials designed to have predetermined structures, compositions and properties. In particular, highly porous frameworks held together by strong metal-oxygen-carbon bonds and with exceptionally large surface area and capacity for gas storage have been prepared and their pore metrics systematically varied and functionalized.

A Critical Review of Construct Indicators and Measurement Model Misspecification in Marketing and Consumer Research

Abstract: A review of the literature suggests that few studies use formative indicator measurement models, even though they should. Therefore, the purpose of this research is to (a) discuss the distinction between formative and reflective measurement models, (b) develop a set of conceptual criteria that can be used to determine whether a construct should be modeled as having formative or reflective indicators, (c) review the marketing literature to obtain an estimate of the extent of measurement model misspecification in the field, (d) estimate the extent to which measurement model misspecification biases estimates of the relationships between constructs using a Monte Carlo simulation, and (e) provide recommendations for modeling formative indicator constructs.

Fluorescence excitation-emission matrix regional integration to quantify spectra for dissolved organic matter.

Abstract: Excitation−emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation−emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation−emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (Φi,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet−visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 h...

Boards of Directors and Firm Performance: Integrating Agency and Resource Dependence Perspectives

Abstract: Boards of directors serve two important functions for organizations: monitoring management on behalf of shareholders and providing resources. Agency theorists assert that effective monitoring is a function of a board's incentives, whereas resource dependence theorists contend that the provision of resources is a function of board capital. We combine the two perspectives and argue that board capital affects both board monitoring and the provision of resources and that board incentives moderate these relationships.

Feature selection for high-dimensional data: a fast correlation-based filter solution

Abstract: Feature selection, as a preprocessing step to machine learning, is effective in reducing dimensionality, removing irrelevant data, increasing learning accuracy, and improving result comprehensibility. However, the recent increase of dimensionality of data poses a severe challenge to many existing feature selection methods with respect to efficiency and effectiveness. In this work, we introduce a novel concept, predominant correlation, and propose a fast filter method which can identify relevant features as well as redundancy among relevant features without pairwise correlation analysis. The efficiency and effectiveness of our method is demonstrated through extensive comparisons with other methods using real-world data of high dimensionality

Biogeochemical Hot Spots and Hot Moments at the Interface of Terrestrial and Aquatic Ecosystems

Abstract: Rates and reactions of biogeochemical processes vary in space and time to produce both hot spots and hot moments of elemental cycling. We define biogeochemical hot spots as patches that show disproportionately high reaction rates relative to the surrounding matrix, whereas hot moments are defined as short periods of time that exhibit disproportionately high reaction rates relative to longer intervening time periods. As has been appreciated by ecologists for decades, hot spot and hot moment activity is often enhanced at terrestrial-aquatic interfaces. Using examples from the carbon (C) and nitrogen (N) cycles, we show that hot spots occur where hydrological flowpaths converge with substrates or other flowpaths containing complementary or missing reactants. Hot moments occur when episodic hydrological flowpaths reactivate and/or mobilize accumulated reactants. By focusing on the delivery of specific missing reactants via hydrologic flowpaths, we can forge a better mechanistic understanding of the factors that create hot spots and hot moments. Such a mechanistic understanding is necessary so that biogeochemical hot spots can be identified at broader spatiotemporal scales and factored into quantitative models. We specifically recommend that resource managers incorporate both natural and artificially created biogeochemical hot spots into their plans for water quality management. Finally, we emphasize the needs for further research to assess the potential importance of hot spot and hot moment phenomena in the cycling of different bioactive elements, improve our ability to predict their occurrence, assess their importance in landscape biogeochemistry, and evaluate their utility as tools for resource management.

Managing Resources: Linking Unique Resources, Management and Wealth Creation in Family Firms

Abstract: The appropriate resources are necessary but insufficient to achieve a competitive advantage. Resources must also be managed effectively. Herein, we develop a resource management process model composed of three components that can lead to a competitive advantage. These components include the resource inventory (evaluating, adding, and shedding), resource bundling, and resource leveraging. We examine resource management in family firms and thus explore the unique characteristics of five resources and attributes of family firms that provide potential advantages over nonfamily firms. The resources are human capital, social capital, patient capital, survivability capital, along with the governance structure attribute.

Measurement of Single-Molecule Resistance by Repeated Formation of Molecular Junctions

Abstract: The conductance of a single molecule connected to two gold electrodes was determined by repeatedly forming thousands of gold-molecule-gold junctions. Conductance histograms revealed well-defined peaks at integer multiples of a fundamental conductance value, which was used to identify the conductance of a single molecule. The resistances near zero bias were 10.5 +/- 0.5, 51 +/- 5, 630 +/- 50, and 1.3 +/- 0.1 megohms for hexanedithiol, octanedithiol, decanedithiol, and 4,4' bipyridine, respectively. The tunneling decay constant (betaN) for N-alkanedithiols was 1.0 +/- 0.1 per carbon atom and was weakly dependent on the applied bias. The resistance and betaN values are consistent with first-principles calculations.

Managing Resources: Linking Unique Resources, Management, and Wealth Creation in Family Firms

Abstract: The appropriate resources are necessary but insufficient to achieve a competitive advantage. Resources must also be managed effectively. Herein, we develop a resource management process model composed of three components that can lead to a competitive advantage. These components include the resource inventory (evaluating, adding, and shedding), resource bundling, and resource leveraging. We examine resource management in family firms and thus explore the unique characteristics of five resources and attributes of family firms that provide potential advantages over nonfamily firms. The resources are human capital, social capital, patient capital, survivability capital, along with the governance structure attribute.

Ferromagnetism above room temperature in bulk and transparent thin films of Mn-doped ZnO

Abstract: The search for ferromagnetism above room temperature in dilute magnetic semiconductors has been intense in recent years. We report the first observations of ferromagnetism above room temperature for dilute ( 700 °C) methods were used, samples were found to exhibit clustering and were not ferromagnetic at room temperature. This capability to fabricate ferromagnetic Mn-doped ZnO semiconductors promises new spintronic devices as well as magneto-optic components.

Knowledge representation, reasoning and declarative problem solving

Abstract: Knowledge management and knowledge-based intelligence are areas of importance in today's economy and society, and their exploitation requires representation via the development of a declarative interface whose input language is based on logic. Chitta Baral demonstrates how to write programs that behave intelligently by giving them the ability to express knowledge and reason about it. He presents a language, AnsProlog, for both knowledge representation and reasoning, and declarative problem solving. Many of the results have never appeared before in book form but are organized here for those wishing to learn more about the subject, either in courses or through self-study.

Crafting Normative Messages to Protect the Environment

Abstract: It is widely recognized that communications that activate social norms can be effective in producing societally beneficial conduct. Not so well recognized are the circumstances under which normative information can backfire to produce the opposite of what a communicator intends. There is an understandable, but misguided, tendency to try to mobilize action against a problem by depicting it as regrettably frequent. Information campaigns emphasize that alcohol and drug use is intolerably high, that adolescent suicide rates are alarming, and—most relevant to this article—that rampant polluters are spoiling the environment. Although these claims may be both true and well intentioned, the campaigns’ creators have missed something critically important: Within the statement “Many people are doing this undesirable thing” lurks the powerful and undercutting normative message “Many people are doing this.” Only by aligning descriptive norms (what people typically do) with injunctive norms (what people typically approve or disapprove) can one optimize the power of normative appeals. Communicators who fail to recognize the distinction between these two types of norms imperil their persuasive efforts.

Spectroscopic Discovery of the Supernova 2003dh Associated with GRB 030329

Abstract: We present early observations of the afterglow of GRB 030329 and the spectroscopic discovery of its associated supernova SN 2003dh. We obtained spectra of the afterglow of GRB 030329 each night from March 30.12 (0.6 days after the burst) to April 8.13 (UT) (9.6 days after the burst). The spectra cover a wavelength range of 350-850 nm. The early spectra consist of a power-law continuum (Fν ν-0.9) with narrow emission lines originating from H II regions in the host galaxy, indicating a low redshift of z = 0.1687. However, our spectra taken after 2003 April 5 show broad peaks in flux characteristic of a supernova. Correcting for the afterglow emission, we find that the spectrum of the supernova is remarkably similar to the Type Ic hypernova SN 1998bw. While the presence of supernovae has been inferred from the light curves and colors of gamma-ray burst afterglows in the past, this is the first direct, spectroscopic confirmation that a subset of classical gamma-ray bursts originate from supernovae.

Charge Transfer on the Nanoscale: Current Status

Abstract: This is the report of a DOE-sponsored workshop organized to discuss the status of our understanding of charge-transfer processes on the nanoscale and to identify research and other needs for progress in nanoscience and nanotechnology. The current status of basic electron-transfer research, both theoretical and experimental, is addressed, with emphasis on the distance-dependent measurements, and we have attempted to integrate terminology and notation of solution electron-transfer kinetics with that of conductance analysis. The interface between molecules or nanoparticles and bulk metals is examined, and new research tools that advance description and understanding of the interface are presented. The present state-of-the-art in molecular electronics efforts is summarized along with future research needs. Finally, novel strategies that exploit nanoscale architectures are presented for enhancing the efficiences of energy conversion based on photochemistry, catalysis, and electrocatalysis principles.

Ionic liquids: Ion mobilities, glass temperatures, and fragilities

Abstract: We combine old, unpublished data on ionic liquids containing quaternary ammonium cations with new data on salts of aromatic cations containing a variety of anions, to demonstrate the existence for ionic liquids of an unexpectedly wide range of liquid fragilities. The pattern is one now familiar for other liquids. Here, the pattern is important in determining the relative fluid properties at ambient temperatures. We find that the optimization of ionic liquids for ambient temperature applications requiring low-vapor-pressure fluid phases involves the proper interplay of both cohesive energy and fragility factors. The cohesive energy is discussed in terms of the coulomb and van der Waals contributions to the attractive part of the pair potential. On the basis of the relation between the glass-transition temperature and the molar volume for salts with less-polarizable anions, we find evidence for a broad minimum in the ionic liquid cohesive energy at an internuclear separation of ca. 0.6 nm. This minimum lies...

Pharmaceuticals, Personal Care Products, and Endocrine Disruptors in Water: Implications for the Water Industry

Abstract: For over 70 years, scientists have reported that certain synthetic and natural compounds could mimic natural hormones in the endocrine systems of animals. These substances are now collectively known as endocrine-disrupting compounds (EDCs), and have been linked to a variety of adverse effects in both humans and wildlife. More recently, pharmaceuticals and personal care products (PPCPs) have been discovered in various surface and ground waters, some of which have been linked to ecological impacts at trace concentrations. The majority of EDCs and PPCPs are more polar than traditional contaminants and several have acidic or basic functional groups. These properties, coupled with occurrence at trace levels (i.e., <1 μg/L), create unique challenges for both removal processes and analytical detection. Reports of EDCs and PPCPs in water have raised substantial concern among the public and regulatory agencies; however, very little is known about the fate of these compounds during drinking and wastewater treatment...

Spectroscopic Discovery of the Supernova 2003dh Associated with GRB 030329

Abstract: We present early observations of the afterglow of the Gamma-Ray Burst (GRB) 030329 and the spectroscopic discovery of its associated supernova SN 2003dh. We obtained spectra of the afterglow of GRB 030329 each night from March 30.12 (0.6 days after the burst) to April 8.13 (UT) (9.6 days after the burst). The spectra cover a wavelength range of 350 nm to 850 nm. The early spectra consist of a power-law continuum (F_nu ~ nu^{-0.9}) with narrow emission lines originating from HII regions in the host galaxy, indicating a low redshift of z=0.1687. However, our spectra taken after 2003 Apr. 5 show broad peaks in flux characteristic of a supernova. Correcting for the afterglow emission, we find the spectrum of the supernova is remarkably similar to the type Ic `hypernova' SN 1998bw. While the presence of supernovae have been inferred from the light curves and colors of GRB afterglows in the past, this is the first direct, spectroscopic confirmation that a subset of classical gamma-ray bursts originate from supernovae.

Resilience and Vulnerability: Adaptation in the Context of Childhood Adversities

Abstract: 1. A resilience framework for research, policy, and practice: contributions from Project Competence Ann S. Masten and Jenifer L. Powell Part I. Familial Adversities: Parental Psychopathology and Family Processes: 2. Young children with mentally ill parents: resilient developmental systems Ronald Seifer 3. Risk and protective factors for children of depressed parents Constance Hammen 4. Resilience and vulnerability among sons of alcoholics: relationship to developmental outcomes between early childhood and adolescence Robert A. Zucker, Maria W. Wong, Leon I. Puttler, and Hiram E. Fitzgerald 5. Maternal drug abuse versus other psychological disturbances: risks and resilience among children Suniya S. Luthar, Karen D'Avanzo and Sarah Hites 6. Resilience to childhood adversity: results of a 21 year study David M. Fergusson and L. John Horwood 7. Sequelae of child maltreatment: vulnerability and resilience Kerry E. Bolger and Charlotte J. Patterson 8. Risk and resilience in children coping with their parents' divorce and remarriage E. Mavis Hetherington and Anne Mitchell Elmore 9. Correlational and experimental study of resilience for children of divorce and parentally bereaved children Irwin Sandler, Sharlene Wolchik, Caroline Davis, Rachel Haine and Tim Ayers Part II. Exosystemic and Sociodemographic Risks: 10. Rethinking resilience: a developmental process perspective Tuppett M. Yates, Byron Egeland and L. Alan Sroufe 11. Poverty and early childhood adjustment Elizabeth B. Owens and Daniel S. Shaw 12. Emerging perspectives on context-specificity of children's adaptation and resilience: evidence from a decade of research with urban children in adversity Peter A. Wyman 13. Holistic, contextual perspectives on risk, protection, and competence among low-income urban adolescents Edward Seidman and Sara Pedersen 14. Overcoming the odds? Adolescent development in the context of urban poverty Ana Mari Cauce, Angela Stewart, Melanie Domenech Rodriguez, Bryan Cochran, and Joshua Ginzler 15. Adaptation among youth facing multiple risks: prospective research findings Arnold Sameroff, Leslie Gutman and Steve C. Peck 16. Positive adaptation among youth exposed to community violence Deborah Gorman-Smith and Patrick H. Tolan 17. Perceived discrimination and resilience Laura A. Szalacha, Sumru Erkut, Cynthia Garcia Coll, Jacqueline P. Fields, Odette Alarcon and Ineke Ceder 18. Promoting resilience through early childhood intervention Arthur J. Reynolds and Suh-Ruu Ou Part III. Commentaries: 19. Toward building a better brain: neurobehavioral outcomes, mechanisms, and processes of environmental enrichment John W. Curtis and Charles A. Nelson 20. Genetic influences on risk and protection: implications for understanding resilience Michael Rutter 21. Resilience and vulnerability: an integrative review Suniya S. Luthar and Laurel Bidwell Zelazo.

Comparison of Electronic Transport Measurements on Organic Molecules

Abstract: We compile, compare, and discuss experimental results on low bias, room-temperature currents through orgnaic molecules obtained in different electrode-molecule-electrode test-beds. Currents are normalized to single-molecule values for comparison and are quoted at 0.2 and 0.5 V junction bias. Emphasis is on currents through saturated alkane chains where many comparable measurements have been reported, but comparison to conjugated molecules is also made. We discuss factors that affect the magnitude of the measured current, such as tunneling attenuation factor, molecular energy gap and conformation, molecule/electrode contacts, and electrode material.

Subduction factory 1. Theoretical mineralogy, densities, seismic wave speeds, and H 2 O contents

Abstract: [1] We present a new compilation of physical properties of minerals relevant to subduction zones and new phase diagrams for mid-ocean ridge basalt, lherzolite, depleted lherzolite, harzburgite, and serpentinite. We use these data to calculate H2O content, density and seismic wave speeds of subduction zone rocks. These calculations provide a new basis for evaluating the subduction factory, including (1) the presence of hydrous phases and the distribution of H2O within a subduction zone; (2) the densification of the subducting slab and resultant effects on measured gravity and slab shape; and (3) the variations in seismic wave speeds resulting from thermal and metamorphic processes at depth. In considering specific examples, we find that for ocean basins worldwide the lower oceanic crust is partially hydrated (<1.3 wt % H2O), and the uppermost mantle ranges from unhydrated to � 20% serpentinized (� 2.4 wt % H2O). Anhydrous eclogite cannot be distinguished from harzburgite on the basis of wave speeds, but its � 6% greater density may render it detectable through gravity measurements. Subducted hydrous crust in cold slabs can persist to several gigapascals at seismic velocities that are several percent slower than the surrounding mantle. Seismic velocities and VP/VS ratios indicate that mantle wedges locally reach 60–80% hydration. INDEX TERMS: 3040 Marine Geology and Geophysics: Plate tectonics (8150, 8155, 8157, 8158); 3660 Mineralogy and Petrology: Metamorphic petrology; 3919 Mineral Physics: Equations of state; 5199 Physical Properties of Rocks: General or miscellaneous; 8123 Tectonophysics: Dynamics, seismotectonics; KEYWORDS: subduction, seismic velocities, mineral physics, H2O

Subduction factory 2. Are intermediate-depth earthquakes in subducting slabs linked to metamorphic dehydration reactions?

Abstract: [1] New thermal-petrologic models of subduction zones are used to test the hypothesis that intermediate-depth intraslab earthquakes are linked to metamorphic dehydration reactions in the subducting oceanic crust and mantle. We show that there is a correlation between the patterns of intermediate-depth seismicity and the locations of predicted hydrous minerals: Earthquakes occur in subducting slabs where dehydration is expected, and they are absent from parts of slabs predicted to be anhydrous. We propose that a subductingoceanicplatecanconsistoffourpetrologicallyandseismicallydistinctlayers:(1) hydrated, fine-grained basaltic upper crust dehydrating under equilibrium conditions and producing earthquakes facilitated by dehydration embrittlement; (2) coarse-grained, locally hydrated gabbroic lower crust that produces some earthquakes during dehydration but transformschieflyaseismicallytoeclogiteatdepthsbeyondequilibrium;(3)locallyhydrated uppermost mantle dehydrating under equilibrium conditions and producing earthquakes; and (4) anhydrous mantle lithosphere transforming sluggishly and aseismically to denser minerals. Fluid generated through dehydration reactions can move via at least three distinct flowpaths:percolationthroughlocal,transient,reaction-generatedhigh-permeabilityzones; flow through mode I cracks produced by the local stress state; and postseismic flow through fault zones. INDEX TERMS: 7218 Seismology: Lithosphere and upper mantle; 7230 Seismology: Seismicity and seismotectonics; 8123 Tectonophysics: Dynamics, seismotectonics; 8135 Tectonophysics: Evolution of the Earth: Hydrothermalsystems (8424); 3660 Mineralogyand Petrology: Metamorphicpetrology;

Ionic Liquids by Proton Transfer: Vapor Pressure, Conductivity, and the Relevance of ΔpKa from Aqueous Solutions

Abstract: We describe the behavior of the conductivity, viscosity, and vapor pressure of various binary liquid systems in which proton transfer occurs between neat Bronsted acids and bases to form salts with melting points below ambient. Such liquids form an important subgroup of the ionic liquid (IL) class of reaction media and electrolytes on which so much attention is currently being focused. Such “protic ionic liquids” exhibit a wide range of thermal stabilities. We find a simple relation between the limit set by boiling, when the total vapor pressure reaches one atm, and the difference in pKa value for the acid and base determined in dilute aqueous solutions. For ΔpKa values above 10, the boiling point elevation becomes so high (>300 °C) that preemptive decomposition prevents its measurement. The completeness of proton transfer in such cases is suggested by the molten salt-like values of the Walden product, which is used to distinguish good from poor ionic liquids. For the good ionic liquids, the hydrogen bond...

X-ray image reconstruction from a diffraction pattern alone

Abstract: A solution to the inversion problem of scattering would offer aberration-free diffraction-limited three-dimensional images without the resolution and depth-of-field limitations of lens-based tomographic systems. Powerful algorithms are increasingly being used to act as lenses to form such images. Current image reconstruction methods, however, require the knowledge of the shape of the object and the low spatial frequencies unavoidably lost in experiments. Diffractive imaging has thus previously been used to increase the resolution of images obtained by other means. Here we experimentally demonstrate an inversion method, which reconstructs the image of the object without the need for any such prior knowledge.