Showing papers by "University of Houston published in 2005"

Circadian rhythms from multiple oscillators: lessons from diverse organisms

Abstract: The organization of biological activities into daily cycles is universal in organisms as diverse as cyanobacteria, fungi, algae, plants, flies, birds and man. Comparisons of circadian clocks in unicellular and multicellular organisms using molecular genetics and genomics have provided new insights into the mechanisms and complexity of clock systems. Whereas unicellular organisms require stand-alone clocks that can generate 24-hour rhythms for diverse processes, organisms with differentiated tissues can partition clock function to generate and coordinate different rhythms. In both cases, the temporal coordination of a multi-oscillator system is essential for producing robust circadian rhythms of gene expression and biological activity.

Highly Regioselective Arylation of sp3 C−H Bonds Catalyzed by Palladium Acetate

Abstract: A new palladium-catalyzed arylation process based on C−H activation has been developed. The utilization of pyridine-containing directing groups allows the β-arylation of carboxylic acid derivatives and γ-arylation of amine derivatives. Both primary and secondary sp3 C−H bonds, as well as sp2 C−H bonds, are reactive.

On the use of beta coefficients in meta-analysis.

Abstract: This research reports an investigation of the use of standardized regression (beta) coefficients in meta-analyses that use correlation coefficients as the effect-size metric. The investigation consisted of analyzing more than 1,700 corresponding beta coefficients and correlation coefficients harvested from published studies. Results indicate that, under certain conditions, using knowledge of corresponding beta coefficients to input missing correlations (effect sizes) generally produces relatively accurate and precise population effect-size estimates. Potential benefits from applying this knowledge include smaller sampling errors because of increased numbers of effect sizes and smaller non-sampling errors because of the inclusion of a broader array of research designs.

Functional- and abundance-based mechanisms explain diversity loss due to N fertilization.

Abstract: Human activities have increased N availability dramatically in terrestrial and aquatic ecosystems. Extensive research demonstrates that local plant species diversity generally declines in response to nutrient enrichment, yet the mechanisms for this decline remain unclear. Based on an analysis of >900 species responses from 34 N-fertilization experiments across nine terrestrial ecosystems in North America, we show that both trait-neutral and trait-based mechanisms operate simultaneously to influence diversity loss as production increases. Rare species were often lost because of soil fertilization, randomly with respect to traits. The risk of species loss due to fertilization ranged from >60% for the rarest species to 10% for the most abundant species. Perennials, species with N-fixing symbionts, and those of native origin also experienced increased risk of local extinction after fertilization, regardless of their initial abundance. Whereas abundance was consistently important across all systems, functional mechanisms were often system-dependent. As N availability continues to increase globally, management that focuses on locally susceptible functional groups and generally susceptible rare species will be essential to maintain biodiversity.

Antecedents and Consequences of Customer – Company Identification: Expanding the Role of Relationship Marketing

Abstract: This article presents an empirical test of organizational identification in the context of customer–company (C-C) relationships. It investigates whether customers identify with companies and what the antecedents and consequences of such identification are. The model posits that perceived company characteristics, construed external image, and the perception of the company’s boundary-spanning agent lead to C-C identification. In turn, such identification is expected to impact both in-role behavior (i.e., product utilization) as well as extra-role behavior (i.e., citizenship). The model was tested in a consultative selling context of pharmaceutical sales reps calling on physicians. Results from the empirical test indicated that customers do indeed identify with organizations and that C-C identification positively impacts both product utilization behavior and extra-role behavior even when the effect of brand perception is accounted for. Second, the study found that the organization’s characteristics as well as the salesperson’s characteristics contributed to the development of C-C identification.

To Empower or Not to Empower Your Sales Force? An Empirical Examination of the Influence of Leadership Empowerment Behavior on Customer Satisfaction and Performance

Abstract: This research focuses on the impact of leadership empowerment behavior (LEB) on customer service satisfaction and sales performance, as mediated by salespeople’s self-efficacy and adapt ability. Moreover, the authors propose an interactive relationship whereby LEB will be differentially effective as a function of employees’ empowerment readiness. The authors’ hypotheses are tested using survey data from a sample of 231 salespeople in the pharmaceutical field, along with external ratings of satisfaction from 864 customers and archival sales performance information. Results indicated that contrary to popular belief, employees with low levels of product/industry knowledge and low experience benefit the most from leadership behaviors that are empowering, whereas high-knowledge and experienced employees reap no clear benefit. The authors conclude with directions for future research and application.

Antecedents and consequences of customer-company identification: expanding the role of relationship marketing.

Abstract: This article presents an empirical test of organizational identification in the context of customer-company (C-C) relationships It investigates whether customers identify with companies and what the antecedents and consequences of such identification are The model posits that perceived company characteristics, construed external image, and the perception of the company's boundary-spanning agent lead to C-C identification In turn, such identification is expected to impact both in-role behavior (ie, product utilization) as well as extra-role behavior (ie, citizenship) The model was tested in a consultative selling context of pharmaceutical sales reps calling on physicians Results from the empirical test indicated that customers do indeed identify with organizations and that C-C identification positively impacts both product utilization behavior and extra-role behavior even when the effect of brand perception is accounted for Second, the study found that the organization's characteristics as well as the salesperson's characteristics contributed to the development of C-C identification

To Empower or Not to Empower Your Sales Force? An Empirical Examination of the Influence of Leadership Empowerment Behavior on Customer Satisfaction and Performance.

Abstract: This research focuses on the impact of leadership empowerment behavior (LEB) on customer service satisfaction and sales performance, as mediated by salespeople's self-efficacy and adaptability. Moreover, the authors propose an interactive relationship whereby LEB will be differentially effective as a function of employees' empowerment readiness. The authors' hypotheses are tested using survey data from a sample of 231 salespeople in the pharmaceutical field, along with external ratings of satisfaction from 864 customers and archival sales performance information. Results indicated that contrary to popular belief, employees with low levels of product/industry knowledge and low experience benefit the most from leadership behaviors that are empowering, whereas high-knowledge and experienced employees reap no clear benefit. The authors conclude with directions for future research and application.

Job Stress, Incivility, and Counterproductive Work Behavior (CWB): The Moderating Role of Negative Affectivity

Abstract: The current study was designed to replicate findings from previous research regarding the relationships between job stressors, negative affectivity, and counterproductive work behavior (CWB) using peer-reported data and to assess the effects of workplace incivility on employee satisfaction and CWB. Results indicate that incivility, organizational constraints, and interpersonal conflict were negatively related to job satisfaction and positively related to CWB. Support was also found for the role of negative affectivity as a moderator of the relationship between job stressors and CWB, although only one significant moderator was found using peer-reported CWB. In general, the relationships between job stressors and CWB were stronger for individuals high in negative affectivity than for individuals low in negative affectivity. Copyright © 2005 John Wiley & Sons, Ltd.

Review: it-dependent strategic initiatives and sustained competitive advantage: a review and synthesis of the literature

Abstract: The role of information systems in the creation and appropriation of economic value has a long tradition of research, within which falls the literature on the sustainability of IT-dependent competitive advantage. In this article, we formally define the notion of IT-dependent strategic initiative and use it to frame a review of the literature on the sustain- ability of competitive advantage rooted in information systems use. We offer a framework that articulates both the dynamic approach to IT-dependent strategic advantage currently receiving attention in the literature and the underlying drivers of sustainability. This framework models how and why the characteristics of the IT-dependent strategic initiative enable sustained competitive advantage, and how the determinants of sustainability are developed and strengthened over time. Such explanation facilitates the pre-implementation analysis of planned initiatives by innovators, as well as the post-implementation evaluation of existing initiatives so as to identify the basis of their sustainability. In carrying out this study, we examined the interdisciplinary literature on strategic information systems. Using a structured methodology, we reviewed the titles and abstracts of 648 articles drawn from information systems, strategic management, and marketing literature. We then examined and individually coded a relevant subset of 117 articles. The literature has identified four barriers to erosion of competitive advantage for IT-dependent strategic initiatives and has surfaced the structural determinants of their magnitude. Previous work has also begun to theorize about the process by which these barriers to erosion evolve over time. Our review reveals that significant exploratory research and theoretical development have occurred in this area, but there is a paucity of research providing rigorous tests of theoretical propositions. Our work makes three principal contributions. First, it formalizes the definition of IT-dependent strategic initiative. Second, it organizes the extant interdisciplinary research around an integrative framework that should prove useful to both research and practice. This framework offers an explanation of how and why IT-dependent strategic initiatives contribute to sustained competitive advantage, and explains the process by which they evolve over time. Finally, our review and analysis of the literature offers the basis for future research directions.

A Review of Antimicrobial Peptides and Their Therapeutic Potential as Anti-Infective Drugs

Abstract: Purpose: Antimicrobial peptides (AMPs) are an essential part of innate immunity that evolved in most living organisms over 2.6 billion years to combat microbial challenge. These small cationic peptides are multifunctional as effectors of innate immunity on skin and mucosal surfaces and have demonstrated direct antimicrobial activity against various bacteria, viruses, fungi, and parasites. This review summarizes their progress to date as commercial antimicrobial drugs for topical and systemic indications. Methods: Literature review. Results: Despite numerous clinical trials, no modified AMP has obtained Food & Drug Administration approval yet for any topical or systemic medical indications. Conclusions: While AMPs are recognized as essential components of natural host innate immunity against microbial challenge, their usefulness as a new class of antimicrobial drugs still remains to be proven.

The Determinants of Credit Default Swap Premia

Abstract: Using a new dataset of bid and offer quotes for credit default swaps, we investigate the relationship between theoretical determinants of default risk and actual market premia using linear regression. These theoretical determinants are firm leverage, volatility and the riskless interest rate. We find that estimated coefficients for these variables are consistent with theory and that the estimates are highly significant both statistically and economically. The explanatory power of the theoretical variables for levels of default swap premia is approximately 60%. The explanatory power for the differences in the premia is approximately 23%. Volatility and leverage by themselves also have substantial explanatory power for credit default swap premia. A principal component analysis of the residuals and the premia shows that there is only weak evidence for a residual common factor and also suggests that the theoretical variables explain a significant amount of the variation in the data. We therefore conclude that leverage, volatility and the riskfree rate are important determinants of credit default swap premia, as predicted by theory.

Zygomycosis in a Tertiary-Care Cancer Center in the Era of Aspergillus-Active Antifungal Therapy: A Case-Control Observational Study of 27 Recent Cases

Abstract: Background. Anecdotal evidence suggests a rise in zygomycosis in association with voriconazole (VRC) use in immunosuppressed patients. Methods. We performed prospective surveillance of patients with zygomycosis (group A; n = 27) and compared them with contemporaneous patients with invasive aspergillosis (group B; n = 54) and with matched contemporaneous high-risk patients without fungal infection (group C; n = 54). We also performed molecular typing and in vitro susceptibility testing of Zygomycetes isolates. Results. Nearly all patients with zygomycosis either had leukemia (n = 14) or were allogeneic bone marrow transplant recipients (n = 13). The Zygomycetes isolates (74% of which were of the genus Rhizopus) had different molecular fingerprinting profiles, and all were VRC resistant. In multivariate analysis of groups A and C, VRC prophylaxis (odds ratio [OR], 10.37 [95% confidence interval {CI}], 2.76-38.97]; P = .001), diabetes (OR, 8.39 [95% CI, 2.04-34.35]; P = .003), and malnutrition (OR, 3.70 [95% CI, 1.03-13.27]; P = .045) were found to be independent risk factors for zygomycosis. Between patients with zygomycosis (after excluding 6 patients with mixed mold infections) and patients with aspergillosis, VRC prophylaxis (OR, 20.30 [95% CI, 3.85-108.15]; P = .0001) and sinusitis (OR, 76.72 [95% CI, 6.48-908.15]; P = .001) were the only factors that favored the diagnosis of zygomycosis. Conclusions. Zygomycosis should be considered in immunosuppressed patients who develop sinusitis while receiving VRC prophylaxis, especially those with diabetes and malnutrition.

Improvisation and Innovative Performance in Teams

Abstract: This paper builds on the principles and insights from improvisational theater to unpack the nature of collective improvisation and to consider what it takes to do it well and to innovate. Furthermore, we discuss the role of training in enhancing the incidence and effectiveness of improvisation. We propose that two common misconceptions about improvisation have hindered managers' understanding of how to develop the improvisational skill. First, the spontaneous facet of improvisation tends to be overemphasized, and second, there is a general assumption that improvisation always leads to positive performance. Our goal is to clear up the conceptual confusion about improvisation by laying out the various aspects of preparation that are required for effective improvisation. In our theoretical model, we delineate how the improvisational theater principles of "practice," "collaboration," "agree, accept, and add," "be present in the moment," and "draw on reincorporation and ready-mades" can be used to understand what it takes to improvise well in work teams and to create a context favoring these efforts. Our findings support a contingent view of the impact of improvisation on innovative performance. Improvisation is not inherently good or bad; however, improvisation has a positive effect on team innovation when combined with team and contextual moderating factors. We also provide initial evidence suggesting that the improvisational skill can be learned by organizational members through training. Our results shed light on the opportunities provided by training in improvisation and on the challenges of creating behavioral change going beyond the individual to the team and, ultimately, to the organization.

Development of Phonological Awareness

Abstract: Phonological awareness is critical for learning to read in alphabetic languages like English. This report summarizes normal development of phonological awareness as it has been revealed through recent multidisciplinary and cross-cultural research. We argue that a consensus on the definition of phonological awareness has emerged, that research has identified a general sequence of phonological awareness development that is universal across languages, and that certain characteristics of spoken and written languages influence the rate of normal development and levels of phonological awareness that are normally achieved.

A New Family of Ru Complexes for Water Oxidation

Abstract: Reaction of the bridging ligand 3,6-bis-[6‘-(1‘ ‘,8‘ ‘-naphthyrid-2‘ ‘-yl)-pyrid-2‘-yl]pyridazine (1) with [Ru(DMSO)4Cl2] in aqueous ethanol followed by excess 4-substituted pyridine (4-R-py) in the presence of triethylamine provides a series of three well-organized dinuclear complexes characterized by 1H NMR, MS, and X-ray. Mononuclear analogues are prepared from 4-tert-butyl-2,6-di(1‘,8‘-naphthyrid-2‘-yl)pyridine (5) and characterized in a similar fashion. All six complexes show electronic absorption and redox properties consistent with the electron donor/acceptor ability of the axial 4-R-py ligand. When an acetonitrile solution of the catalyst is added to an aqueous Ce(IV)-CF3SO3H solution (pH = 1.0) at 24 °C, oxygen evolution is observed for both mono and dinuclear systems. Turnover numbers range from 50 to 3200 with the best results being found when the axial ligand is 4-methylpyridine (mononuclear TN = 580 and dinuclear TN = 3200).

A Cube Model for Competency Development: Implications for Psychology Educators and Regulators

Abstract: This article provides a conceptual framework for training in professional psychology focused on the construct of competency. The authors present a 3-dimensional competency model delineating the domains of knowledge, skills, attitudes, and values that serve as the foundation required of all psychologists, the domains of functional competencies that broadly define what psychologists do, and the stages of professional development from doctoral education to lifelong learning through continuing education. The goal in presenting this model is to provide a conceptual frame of reference for those responsible for psychology education, credentialing, and regulation.

Tracking control of a piezoceramic actuator with hysteresis compensation using inverse Preisach model

Abstract: This paper presents the classical Preisach hysteresis modeling and tracking control of a curved pre-stressed piezoceramic patch actuator system with severe hysteresis The actuator is also flexible with very small inherent damping It has potential applications in active antennas A series of tests are conducted to study the hysteresis properties of the piezoceramic actuator system The numerical expressions of the classical Preisach model for different input variations are presented The classical Preisach model is applied to simulate the static hysteresis behavior of the system Higher order hysteresis reversal curves predicted by the classical Preisach model are verified experimentally The good agreement found between the measured and predicted curves showed that the classical Preisach model is an effective mean for modeling the hysteresis of the piezoceramic actuator system Subsequently, the inverse classical Preisach model is established and applied to cancel the hysteresis the piezoceramic actuator system for the real-time microposition tracking control In order to improve the control accuracy and to increase damping of the actuator system, a cascaded PD/lead-lag feedback controller is designed with consideration of the dynamics of the actuator In the experiments, two cases are considered, control with major loop hysteresis compensation, and control with minor loop hysteresis compensation Experimental results show that RMS tracking errors are reduced by 50% to 70% if the hysteresis compensation is added in the feedforward path in both cases Therefore, hysteresis compensation with the feedback controller greatly improves the tracking control accuracy of the piezoceramic actuator

Did Conservatism in Financial Reporting Increase after the Sarbanes-Oxley Act? Initial Evidence

Abstract: In this paper, we investigate the change in managerial discretion over financial reporting following the Sarbanes-Oxley Act (hereafter SOX). We document an increase in conservatism in financial reporting following SOX and the resulting requirement by the SEC that financial statements be certified by firms' CEOs and CFOs. First, we find that firms report lower discretionary accruals after SOX than in the period preceding SOX. Second, based on the Basu (1997) measure of conservatism, we find that firms incorporate losses more quickly than gains when they report income in the post-SOX period. These results are obtained with alternative estimation and measurement approaches and after controlling for potentially confounding variables. This empirical evidence suggests that SOX and the resultant SEC certification requirement may have altered management's discretionary reporting behavior to make it more conservative.

People are variables too: multilevel structural equations modeling.

Abstract: The article uses confirmatory factor analysis (CFA) as a template to explain didactically multilevel structural equation models (ML-SEM) and to demonstrate the equivalence of general mixed-effects models and ML-SEM. An intuitively appealing graphical representation of complex ML-SEMs is introduced that succinctly describes the underlying model and its assumptions. The use of definition variables (i.e., observed variables used to fix model parameters to individual specific data values) is extended to the case of ML-SEMs for clustered data with random slopes. Empirical examples of multilevel CFA and ML-SEM with random slopes are provided along with scripts for fitting such models in SAS Proc Mixed, Mplus, and Mx. Methodological issues regarding estimation of complex ML-SEMs and the evaluation of model fit are discussed. Further potential applications of ML-SEMs are explored.

Seismic attributes — A historical perspective

Abstract: A seismic attribute is a quantitative measure of a seismic characteristic of interest. Analysis of attributes has been integral to reflection seismic interpretation since the 1930s when geophysicists started to pick traveltimes to coherent reflections on seismic field records. There are now more than 50 distinct seismic attributes calculated from seismic data and applied to the interpretation of geologic structure, stratigraphy, and rock/pore fluid properties. The evolution of seismic attributes is closely linked to advances in computer technology. As examples, the advent of digital recording in the 1960s produced improved measurements of seismic amplitude and pointed out the correlation between hydrocarbon pore fluids and strong amplitudes (“bright spots”). The introduction of color printers in the early 1970s allowed color displays of reflection strength, frequency, phase, and interval velocity to be overlain routinely on black-and-white seismic records. Interpretation workstations in the 1980s provided...

Peripheral vision can influence eye growth and refractive development in infant monkeys.

Abstract: PURPOSE—Given the prominence of central vision in humans, it has been assumed that visual signals from the fovea dominate emmetropization. The purpose of this study was to examine the impact of peripheral vision on emmetropization. METHODS—Bilateral, peripheral form deprivation was produced in 12 infant monkeys by rearing them with diffusers that had either 4- or 8-mm apertures centered on the pupils of each eye, to allow 24° or 37° of unrestricted central vision, respectively. At the end of the lens-rearing period, an argon laser was used to ablate the fovea in one eye of each of seven monkeys. Subsequently, all the animals were allowed unrestricted vision. Refractive error and axial dimensions were measured along the pupillary axis by retinoscopy and A-scan ultrasonography, respectively. Control data were obtained from 21 normal monkeys and 3 infants reared with binocular plano lenses. RESULTS—Nine of the 12 treated monkeys had refractive errors that fell outside the 10th- and 90th-percentile limits for the age-matched control subjects, and the average refractive error for the treated animals was more variable and significantly less hyperopic/more myopic (+0.03 ± 2.39 D vs. +2.39 ± 0.92 D). The refractive changes were symmetric in the two eyes of a given animal and axial in nature. After lens removal, all the treated monkeys recovered from the induced refractive errors. No interocular differences in the recovery process were observed in the animals with monocular foveal lesions.

Tectonic and stratigraphic controls of hydrocarbon systems in the Ordos basin: A multicycle cratonic basin in central China

Abstract: The Ordos basin is the oldest and still an important hydrocarbon province in central China. It is a typical cratonic basin developed on the Archean granulites and lower Proterozoic greenschists of the North China block. The development of the Ordos basin during the Paleozoic–Mesozoic can be divided into three evolutionary stages: Cambrian–Early Ordovician cratonic basin with divergent margins; Middle Ordovician–Middle Triassic cratonic basin with convergent margins; and Late Triassic–Early Cretaceous intraplate remnant cratonic basin. Two hydrocarbon systems are present in the basin: the Paleozoic gas and Mesozoic oil systems. In the Paleozoic gas system, the Lower Ordovician marine carbonates and Pennsylvanian–Lower Permian coal measures serve as source rocks. The Lower Ordovician karst-modified dolomites and Pennsylvanian bauxitic mudstones form a significant reservoir-seal association, and the Pennsylvanian–Lower Permian deltaic sandstones and Upper Permian lacustrine mudstones form another effective reservoir-seal association. In the Mesozoic oil system, the Upper Triassic lacustrine mudstones are mature source rocks. The Upper Triassic deltaic sandstones and overlying shallow-lacustrine and swamp mudstones form a reservoir-seal association, and the Lower Jurassic fluvial sandstones and overlying shallow-lacustrine and swamp mudstones form another reservoir-seal association. In both hydrocarbon systems, the stratigraphic variations provide the principal traps. The Ordos basin is characterized by a stable tectonic setting that controlled the distribution of depositional systems and the development of erosional surfaces and ultimately governed the distribution of oil and gas fields and trap types.

Financial Constraints Risk

Abstract: We construct an index of firms' external finance constraints via GMM estimation of an investment Euler equation. Unlike the commonly used KZ index, ours is consistent with firm characteristics associated with external finance constraints. Constrained firms' returns move together, suggesting the existence of a financial constraints factor. This factor earns a positive but insignificant average return. Much of the variation in this factor cannot be explained by the Fama-French and momentum factors. Cross-sectional regressions of returns on our index and other firm characteristics show that constrained firms earn higher returns and that the financial-constraints effect dominates the size effect.

Tuning the properties of magnetic nanowires

Abstract: Magnetic nanorods or nanowires exhibit degrees of freedom associated with their inherent shape anisotropy and the ability to incorporate different components along their length. The introduction of multiple segments along the length of a nanowire can lead to further degrees of freedom associated with the shape of each segment and the coupling between layers. In this paper, we present an overview of the magnetic properties of single-component and multiple-segment magnetic nanowires, and we provide examples of the influence of particle diameter, aspect ratio, and composition on many of their magnetic properties: the orientation of their magnetic easy axis, their Curie temperature, coercivity, saturation field, saturation magnetization, and remanent magnetization.

Rural Windfall or a New Resource Curse? Coca, Income, and Civil Conflict in Colombia

Abstract: Natural and agricultural resources for which there is a substantial black market, such as coca, opium, and diamonds, appear especially likely to be exploited by the parties to a civil conflict. Even legally traded commodities such as oil and timber have been linked to civil war. On the other hand, these resources may also provide one of the few reliable sources of income in the countryside. In this paper, we study the economic and social consequences of a major exogenous shift in the production of one such resource - coca paste - into Colombia, where most coca leaf is now harvested. Our analysis shows that this shift generated only modest economic gains in rural areas, primarily in the form of increased self-employment earnings and increased labor supply by teenage boys. The results also suggest that the rural areas which saw accelerated coca production subsequently became more violent, while urban areas were affected little. The acceleration in violence is greater in departments (provinces) where there was a pre-coca guerilla presence. Taken together, these findings are consistent with the view that the Colombian civil conflict is fueled by the financial opportunities that coca provides, and that the consequent rent-seeking activity by combatants limits the economic gains from coca cultivation.