Showing papers by "Texas A&M University published in 2001"

Accounting for common method variance in cross-sectional research designs.

Abstract: Cross-sectional studies of attitude-behavior relationships are vulnerable to the inflation of correlations by common method variance (CMV). Here, a model is presented that allows partial correlation analysis to adjust the observed correlations for CMV contamination and determine if conclusions about the statistical and practical significance of a predictor have been influenced by the presence of CMV. This method also suggests procedures for designing questionnaires to increase the precision of this adjustment.

Direct and Moderating Effects of Human Capital on Strategy and Performance in Professional Service Firms: A Resource-Based Perspective

Abstract: The current study examines the direct and moderating effects of human capital on professional service firm performance. The results show that human capital exhibits a curvilinear (U-shaped) effect and the leveraging of human capital a positive effect on performance. Furthermore, the results show that human capital moderates the relationship between strategy and firm performance, thereby supporting a resource-strategy contingency fit. The results contribute to knowledge on the resource-based view of the firm and the strategic importance of human capital.

Customer Satisfaction: A Meta-Analysis of the Empirical Evidence:

Abstract: The growing number of academic studies on customer satisfaction and the mixed findings they report complicate efforts among managers and academics to identify the antecedents to, and outcomes of, businesses having more-versus less-satisfied customers. These mixed findings and the growing emphasis by managers on having satisfied customers point to the value of empirically synthesizing the evidence on customer satisfaction to assess current knowledge. To this end, the authors conduct a meta-analysis of the reported findings on customer satisfaction. They document that equity and disconfirmation are most strongly related to customer satisfaction on average. They also find that measurement and method factors that characterize the research often moderate relationship strength between satisfaction and its antecedents and outcomes. The authors discuss the implications surrounding these effects and offer several directions for future research.

When Job Dissatisfaction Leads to Creativity: Encouraging the Expression of Voice

Abstract: This study focused on the conditions under which job dissatisfaction will lead to creativity as an expression of voice. We theorized that useful feedback from coworkers, coworker helping and support, and perceived organizational support for creativity would each interact with job dissatisfaction and continuance commitment (commitment motivated by necessity) to result in creativity. In a sample of 149 employees, as hypothesized, employees with high job dissatisfaction exhibited the highest creativity when continuance commitment was high and when (1) useful feedback from coworkers, or (2) coworker helping and support, or (3) perceived organizational support for creativity was high.

Dendrimer-Encapsulated Metal Nanoparticles: Synthesis, Characterization, and Applications to Catalysis

Abstract: This Account reports the synthesis and characterization of dendrimer-encapsulated metal nanoparticles and their applications to catalysis. These materials are prepared by sequestering metal ions within dendrimers followed by chemical reduction to yield the corresponding zerovalent metal nanoparticle. The size of such particles depends on the number of metal ions initially loaded into the dendrimer. Intradendrimer hydrogenation and carbon−carbon coupling reactions in water, organic solvents, biphasic fluorous/organic solvents, and supercritical CO2 are also described.

Studying Organizational Change and Development: Challenges for Future Research

Abstract: This article presents several studies that examine organizational change. The authors note that certain issues should be addressed when examining the studies including an examination of the multiple contexts and levels of analysis in studying organizational change, the inclusion of time, history, process and action, the link between change processes and organizational performance, the investigation of international and cross-cultural comparisons, the study of receptivity, customization, sequencing, pace and episodic versus continuous change and the partnership between scholars and practitioners in studying change. The authors discuss how these issues are related to the concepts in the studies and note their research has not addressed these issues at this point in time.

Why Some New Products Are More Successful Than Others

Abstract: Product innovation is increasingly valued as a key component of the sustainable success of a business’s operations. As a result, there has been a noticeable increase in the number of studies directed at explicating the drivers of new product success. To help managers and researchers synthesize this growing body of evidence, the authors conduct a meta-analysis of the new product performance literature. Of the 24 predictors of new product performance investigated, product advantage, market potential, meeting customer needs, predevelopment task proficiencies, and dedicated resources, on average, have the most significant impact on new product performance. The authors also find that the predictor–performance relationships can vary by measurement factor (e.g., the use of multi-item scales, subjective versus objective measures of performance, senior versus project management reporting, time elapsed since product introduction) or contextual factor (e.g., services versus goods, Asian versus North America...

A rate-adaptive MAC protocol for multi-Hop wireless networks

Abstract: Wireless local area networks (W-LANs) have become increasingly popular due to the recent availability of affordable devices that are capable of communicating at high data rates. These high rates are possible, in part, through new modulation schemes that are optimized for the channel conditions bringing about a dramatic increase in bandwidth efficiency. Since the choice of which modulation scheme to use depends on the current state of the transmission channel, newer wireless devices often support multiple modulation schemes, and hence multiple datarates, with mechanisms to switch between them Users are given the option to either select an operational datarate manually or to let the device automatically choose the appropriate modulation scheme (data rate) to match the prevailing conditions. Automatic rate selection protocols have been studied for cellular networks but there have been relatively few proposals for W-LANs. In this paper we present a rate adaptive MAC protocol called the Receiver-Based AutoRate (RBAR) protocol. The novelty of RBAR is that its rate adaptation mechanism is in the receiver instead of in the sender. This is in contrast to existing schemes in devices like the WaveLAN II [15]. We show that RBAR is better because it results in a more efficient channel quality estimation which is then reflected in a higher overall throughput Our protocol is based on the RTS/CTS mechanism and consequently it can be incorporated into many medium access control protocols including the widely popular IEEE 802.11 protocol. Simulation results of an implementation of RBAR inside IEEE 802.11 show that RBAR performs consistently well.

Product Innovation Strategy and the Performance of New Technology Ventures in China

Abstract: Investigating the effect of product innovation strategy on the performance of new technology ventures in China, we found the innovation-performance link was contingent on both environmental factors, including environmental turbulence and institutional support, and the relationship-based strategies of the ventures, such as strategic alliances for product development and political networking. Our results suggest the need for simultaneous consideration of environment- and relationship-based strategy factors as moderators in the discourse on product innovation strategy among new technology ventures.

Catalysis Research of Relevance to Carbon Management: Progress, Challenges, and Opportunities

Abstract: There is increased recognition by the world’s scientific, industrial, and political communities that the concentrations of greenhouse gases in the earth’s atmosphere, particularly CO_2, are increasing. For example, recent studies of Antarctic ice cores to depths of over 3600 m, spanning over 420 000 years, indicate an 80 ppm increase in atmospheric CO_2 in the past 200 years (with most of this increase occurring in the past 50 years) compared to the previous 80 ppm increase that required 10 000 years.2 The 160 nation Framework Convention for Climate Change (FCCC) in Kyoto focused world attention on possible links between CO2 and future climate change and active discussion of these issues continues.3 In the United States, the PCAST report4 “Federal Energy Research and Development for the Challenges of the Twenty First Century” focused attention on the growing worldwide demand for energy and the need to move away from current fossil fuel utilization. According to the U.S. DOE Energy Information Administration,5 carbon emission from the transportation (air, ground, sea), industrial (heavy manufacturing, agriculture, construction, mining, chemicals, petroleum), buildings (internal heating, cooling, lighting), and electrical (power generation) sectors of the World economy amounted to ca. 1823 million metric tons (MMT) in 1990, with an estimated increase to 2466 MMT in 2008-2012 (Table 1).

Stochastic sensors inspired by biology

Abstract: Sensory systems use a variety of membrane-bound receptors, including responsive ion channels, to discriminate between a multitude of stimuli Here we describe how engineered membrane pores can be used to make rapid and sensitive biosensors with potential applications that range from the detection of biological warfare agents to pharmaceutical screening Notably, use of the engineered pores in stochastic sensing, a single-molecule detection technology, reveals the identity of an analyte as well as its concentration

North atlantic climate variability: Phenomena, impacts and mechanisms

Abstract: Variability of the North Atlantic Oscillation and the Tropical Atlantic dominate the climate of the North Atlantic sector, the underlying ocean and surrounding continents on interannual to decadal time scales. Here we review these phenomena, their climatic impacts and our present state of understanding of their underlying cause. Copyright © 2001 Royal Meteorological Society.

The automaticity of complex motor skill learning as a function of attentional focus

Abstract: The present experiment was designed to test the predictions of the constrained-action hypothesis. This hypothesis proposes that when performers utilize an internal focus of attention (focus on their movements) they may actually constrain or interfere with automatic control processes that would normally regulate the movement, whereas an external focus of attention (focus on the movement effect) allows the motor system to more naturally self-organize. To test this hypothesis, a dynamic balance task (stabilometer) was used with participants instructed to adopt either an internal or external focus of attention. Consistent with earlier experiments, the external focus group produced generally smaller balance errors than did the internal focus group and responded at a higher frequency indicating higher confluence between voluntary and reflexive mechanisms. In addition, probe reaction times (RTs) were taken as a measure of the attention demands required under the two attentional focus conditions. Consistent with the hypothesis, the external focus participants demonstrated lower probe RTs than did the internal focus participants, indicating a higher degree of automaticity and less conscious interference in the control processes associated with the balance task.

Supramolecular arrays based on dimetal building units.

Abstract: Supramolecular chemistry is today a major thrust area, a significant part of which is based on the use of metal atoms or ions as key elements in promoting the assembly of and dictating the main structural features of the supramolecular products. Most of the work has been done with single metal atoms or ions in this role, but considerable success has already been achieved by employing M−M bonded dimetal entities instead. We review here the work done in our laboratory. Metal−metal bonded cationic complexes of the [M2(DAniF)n(MeCN)8-2n](4-n)+ type, where M = Mo or Rh and DAniF is an N,N‘-di-p-anisylformamidinate anion, have been used as subunit precursors and then linked by various equatorial and axial bridging groups such as polycarboxylate anions, polypyridyls, and polynitriles. Characterization of the products by single-crystal X-ray diffraction, CV, DPV, NMR, and other spectroscopic techniques has revealed the presence of discrete tetranuclear (pairs or loops), hexanuclear (triangles), octanuclear (squar...

The Evolution of the Goddard Profiling Algorithm (GPROF) for Rainfall Estimation from Passive Microwave Sensors

Abstract: This paper describes the latest improvements applied to the Goddard profiling algorithm (GPROF), particularly as they apply to the Tropical Rainfall Measuring Mission (TRMM). Most of these improvements, however, are conceptual in nature and apply equally to other passive microwave sensors. The improvements were motivated by a notable overestimation of precipitation in the intertropical convergence zone. This problem was traced back to the algorithm's poor separation between convective and stratiform precipitation coupled with a poor separation between stratiform and transition regions in the a priori cloud model database. In addition to now using an improved convective–stratiform classification scheme, the new algorithm also makes use of emission and scattering indices instead of individual brightness temperatures. Brightness temperature indices have the advantage of being monotonic functions of rainfall. This, in turn, has allowed the algorithm to better define the uncertainties needed by the sc...

Sequence-specific detection of individual DNA strands using engineered nanopores.

Abstract: We describe biosensor elements that are capable of identifying individual DNA strands with single-base resolution. Each biosensor element consists of an individual DNA oligonucleotide covalently attached within the lumen of the alpha-hemolysin (alphaHL) pore to form a "DNA-nanopore". The binding of single-stranded DNA (ssDNA) molecules to the tethered DNA strand causes changes in the ionic current flowing through a nanopore. On the basis of DNA duplex lifetimes, the DNA-nanopores are able to discriminate between individual DNA strands up to 30 nucleotides in length differing by a single base substitution. This was exemplified by the detection of a drug resistance-conferring mutation in the reverse transcriptase gene of HIV. In addition, the approach was used to sequence a complete codon in an individual DNA strand tethered to a nanopore.

Observation of ultraslow and stored light pulses in a solid.

Abstract: We report ultraslow group velocities of light in an optically dense crystal of Pr doped ${\mathrm{Y}}_{2}{\mathrm{SiO}}_{5}$. Light speeds as slow as 45 m/s were observed, corresponding to a group delay of 66 \ensuremath{\mu}s. Deceleration and ``stopping'' or trapping of the light pulse was also observed. These reductions of the group velocity are accomplished by using a sharp spectral feature in absorption and dispersion that is produced by resonance Raman excitation of a ground-state spin coherence.

Adipocyte tissue volume in bone marrow is increased with aging and in patients with osteoporosis.

Abstract: Aging of the human skeleton is characterized by decreased boneformation and bone mass and these changes are more pronounced inpatients with osteoporosis. As osteoblasts and adipocytes share a commonprecursor cell in the bone marrow, we hypothesized that decreased boneformation observed during aging and in patients with osteoporosis is theresult of enhanced adipognesis versus osteoblastogenesis from precursorcells in the bone marrow. Thus, we examined iliac crest bone biopsiesobtained from 53 healthy normal individuals (age 30–100) and 26patients with osteoporosis (age 52–92). Adipose tissue volumefraction (AV), hematopoietic tissue volume fraction (HV) and trabecularbone volume fraction (BV) were quantitated as a percentage of totaltissue volume fraction (TV) (calculated as BV + AV + HV) usingthe point-counting method. We found an age-related increase in AV/TV(r = 0.53, p < 0.001, n =53) and an age-related decline in BV/TV (r =−0.46, p < 0.001, n = 53) as well asin the HV/TV (r = −0.318, p <0.05, n = 53). There was an age-related inversecorrelation between BV/TV and AV/TV (r =−0.58, p < 0.001). No significant correlation betweenthe AV/TV and the body mass index (r = 0.06, n.s.,n = 52) was detectable. Compared with age-matchedcontrols, patients with osteoporosis exhibited an increased AV/TV(P < 0.05) and decreased BV/TV (P < 0.05)but no statistically significant difference in HV/TV. Our datasupport the hypothesis that with aging and in osteoporosis an enhancedadipogenesis is observed in the bone marrow and that these changes areinversely correlated to decreased trabecular bone volume. The cellularand molecular mechanisms mediating these changes remain to bedetermined.

Environmental context-dependent memory: a review and meta-analysis.

Abstract: To address questions about human memory’s dependence on the coincidental environmental contexts in which events occur, we review studies of incidental environmental context-dependent memory in humans and report a meta-analysis. Our theoretical approach to the issue stems from Glenberg’s (1997) contention that introspective thought (e.g., remembering, conceptualizing) requires cognitive resources normally used to represent the immediate environment. We propose that if tasks encourage processing of noncontextual information (i.e., introspective thought) at input and/or at test, then both learning and memory will be less dependent on the ambient environmental contexts in which those activities occur. The meta-analysis showed that across all studies, environmental context effects were reliable, and furthermore, that the use of noncontextual cues during learning (overshadowing) and at test (outshining), as well as mental reinstatement of appropriate context cues at test, all reduce the effect of environmental manipulations. We conclude that environmental context-dependent memory effects are less likely to occur under conditions in which the immediate environment is likely to be suppressed.

Psychometric evaluation of the Beck Depression Inventory-II with primary care medical patients.

Abstract: This study evaluated the psychometric characteristics of the Beck Depression Inventory-II (BDI-II; A. T. Beck, R. A. Steer, & G. K. Brown, 1996) in a primary care medical setting. A principal-components analysis with Promax rotation indicated the presence of 2 correlated factors, Somatic-Affective and Cognitive, which explained 53.5% of the variance. A hierarchical, second-order analysis indicated that all items tap into a second-order construct of depression. Evidence for convergent validity was provided by predicted relationships with subscales from the Short-Form General Health Survey (SF-20; A. L. Stewart, R. D. Hayes, & J. E. Ware, 1988). A receiver operating characteristic analysis demonstrated criterion-related validity: BDI-II scores predicted a diagnosis of major depressive disorder (MDD), as determined by the Primary Care Evaluation of Mental Disorders (PRIME-MD) Patient Health Questionnaire (PHQ). This study demonstrated that the BDI-II yields reliable, internally consistent, and valid scores in a primary care medical setting, suggesting that use of the BDI-II in this setting may improve detection and treatment of depression in these medical patients.

Compensatory density dependence in fish populations: importance, controversy, understanding and prognosis

Abstract: Density-dependent processes such as growth, survival, reproduction and movement are compensatory if their rates change in response to variation in population density (or numbers) such that they result in a slowed population growth rate at high densities and promote a numerical increase of the population at low densities. Compensatory density dependence is important to fisheries management because it operates to offset the losses of individuals. While the concept of compensation is straightforward, it remains one of the most controversial issues in population dynamics. The difficulties arise when going from general concepts to specific populations. Compensation is usually quantified using some combination of spawner–recruit analysis, long-term field monitoring or manipulative studies, and computer modelling. Problems arise because there are limitations to each of these approaches, and these limitations generally originate from the high uncertainty associated with field measurements. We offer a hierarchical approach to predicting and understanding compensation that ranges from the very general, using basic life-history theory, to the highly site-specific, using detailed population models. We analyse a spawner–recruit database to test the predictions about compensation and compensatory reserve that derive from a three-endpoint life-history framework designed for fish. We then summarise field examples of density dependence in specific processes. Selected long-term field monitoring studies, manipulative studies and computer modelling examples are then highlighted that illustrate how density-dependent processes led to compensatory responses at the population level. Some theoretical and empirical advances that offer hope for progress in the future on the compensation issue are discussed. We advocate an approach to compensation that involves process-level understanding of the underlying mechanisms, life-history theory, careful analysis of field data, and matrix and individual-based modelling. There will always be debate if the quantification of compensation does not include some degree of understanding of the underlying mechanisms.

Conversion of conventional gravitational-wave interferometers into quantum nondemolition interferometers by modifying their input and/or output optics

Abstract: The LIGO-II gravitational-wave interferometers (ca. 2006–2008) are designed to have sensitivities near the standard quantum limit (SQL) in the vicinity of 100 Hz. This paper describes and analyzes possible designs for subsequent LIGO-III interferometers that can beat the SQL. These designs are identical to a conventional broad band interferometer (without signal recycling), except for new input and/or output optics. Three designs are analyzed: (i) a squeezed-input interferometer (conceived by Unruh based on earlier work of Caves) in which squeezed vacuum with frequency-dependent (FD) squeeze angle is injected into the interferometer’s dark port; (ii) a variational-output interferometer (conceived in a different form by Vyatchanin, Matsko and Zubova), in which homodyne detection with FD homodyne phase is performed on the output light; and (iii) a squeezed-variational interferometer with squeezed input and FD-homodyne output. It is shown that the FD squeezed-input light can be produced by sending ordinary squeezed light through two successive Fabry-Perot filter cavities before injection into the interferometer, and FD-homodyne detection can be achieved by sending the output light through two filter cavities before ordinary homodyne detection. With anticipated technology (power squeeze factor e-2R=0.1 for input squeezed vacuum and net fractional loss of signal power in arm cavities and output optical train e*=0.01) and using an input laser power Io in units of that required to reach the SQL (the planned LIGO-II power, ISQL), the three types of interferometer could beat the amplitude SQL at 100 Hz by the following amounts μ≡sqrt[Sh]/sqrt[ShSQL] and with the following corresponding increase V=1/μ3 in the volume of the universe that can be searched for a given noncosmological source: Squeezed input —μ≃sqrt[e-2R]≃0.3 and V≃1/0.33≃30 using Io/ISQL=1. Variational-output—μ≃e*1/4≃0.3 and V≃30 but only if the optics can handle a ten times larger power: Io/ISQL≃1/sqrt[e*]=10. Squeezed varational —μ=1.3(e-2Re*)1/4≃0.24 and V≃80 using Io/ISQL=1; and μ≃(e-2Re*)1/4≃0.18 and V≃180 using Io/ISQL=sqrt[e-2R/e*]≃3.2.

An examination of the determinants of entertainment vacationers' intentions to revisit.

Abstract: This study investigated the relationship of entertainment travelers’ past vacation behavior, vacation satisfaction, perceived vacation value, and intentions to revisit and repurchase. Subjects were inquirers for the purchase of an entertainment package that visited the destination and were systematically selected over a 12-month period. Results suggest that past behavior, satisfaction, and perceived value are good predictors of entertainment vacationers’ intentions to revisit the destination. It was further found that the variables of past behavior, satisfaction, and perceived value are poor predictors of intentions to visit and attend live theater entertainment or book an entertainment package during a visit. Given the relationships between past behavior, satisfaction, perceived value, and intentions to revisit, results of the present study provide important theoretical implications and direction for entertainment destination management.

Proteolytic exposure of a cryptic site within collagen type IV is required for angiogenesis and tumor growth in vivo.

Abstract: Evidence is provided that proteolytic cleavage of collagen type IV results in the exposure of a functionally important cryptic site hidden within its triple helical structure. Exposure of this cryptic site was associated with angiogenic, but not quiescent, blood vessels and was required for angiogenesis in vivo. Exposure of the HUIV26 epitope was associated with a loss of α1β1 integrin binding and the gain of αvβ3 binding. A monoclonal antibody (HUIV26) directed to this site disrupts integrin-dependent endothelial cell interactions and potently inhibits angiogenesis and tumor growth. Together, these studies suggest a novel mechanism by which proteolysis contributes to angiogenesis by exposing hidden regulatory elements within matrix-immobilized collagen type IV.

Modelling respiration of vegetation: evidence for a general temperature-dependent Q10.

Abstract: Temperature responses of rates of respiratory CO2 efflux from plants, soils, and ecosystems are frequently modelled using exponential functions with a constant Q10 near 2.0 (fractional change in rate with a 10 ∞C increase in temperature). However, we present evidence that Q10 declines with short-term increases in temperature in a predictable manner across diverse plant taxa. Thus, models using a constant Q10 are biased, and use of a temperature-corrected Q10 may improve the accuracy of modelled respiratory CO2 efflux in plants and ecosystems in response to temperature and predicted global climate changes.