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Showing papers by "University of Houston published in 2001"


Journal ArticleDOI
TL;DR: The results indicate that, in the context of IT basic skills training in undergraduate education, there are no significant differences in performance between students enrolled in the two environments, however, the VLE leads to higher reported computer self-efficacy, while participants report being less satisfied with the learning process.
Abstract: Internet technologies are having a significant impact on the learning industry. For-profit organizations and traditional institutions of higher education have developed and are using web-based courses, but little is known about their effectiveness compared to traditional classroom education. Our work focuses on the effectiveness of a web-based virtual learning environment (VLE) in the context of basic information technology skills training. This article provides three main contributions. First, it introduces and defines the concept of VLE, discussing how a VLE differs from the traditional classroom and differentiating it from the related, but narrower, concept of computer aided instruction (CAI). Second, it presents a framework of VLE effectiveness, grounded in the technology-mediated learning literature, which frames the VLE research domain, and addresses the relationship between the main constructs. Finally, it focuses on one essential VLE design variable, learner control, and compares a web-based VLE to a traditional classroom through a longitudinal experimental design. Our results indicate that, in the context of IT basic skills training in undergraduate education, there are no significant differences in performance between students enrolled in the two environments. However, the VLE leads to higher reported computer self-efficacy, while participants report being less satisfied with the learning process.

1,517 citations


Journal ArticleDOI
TL;DR: The phonological processing refers to the use of the sound system of language to process written and oral infonnation, including sensitivity to the sound segments in verbal language (Clark & Uhry, 1995; Harm & Seidenberg, 1999; Mathes & Mathes as mentioned in this paper ).
Abstract: in learning to read are most frequently contributed to weaknesses in the ability to process the phonological features of language (Blachman, 1994; Blachman, Tangel, Ball, Black, & McGraw, 1999; Fletcher & Lyon, 1998; Mathes, Howard, Allen, & Fuchs, 1998; National Research Council, 1998; Torgesen, Wagner, Rashotte, 1994; Torgesen, Wagner, Rashotte, Alexander, & Conway, 1997). The term phonology is of Greek origin, phone meaning &dquo;voice&dquo; or &dquo;sound.&dquo; Phonological processing refers to the use of the sound system of language to process written and oral infonnation, including sensitivity to the sound segments in verbal language (Clark & Uhry, 1995; Harm & Seidenberg, 1999; Mathes &

1,206 citations


Journal ArticleDOI
TL;DR: Perceived user resources are examined, which are measures of self-efficacy and perceived behavioral control that concentrate on how well individuals perceive they can execute specific courses of action, that can facilitate or inhibit such behaviors.
Abstract: There has been considerable research on the factors that predict whether individuals will accept and voluntarily use information systems The technology acceptance model (TAM) has a base in psychological research, is parsimonious, explains usage behavior quite well, and can be operationalized with valid and reliable instruments A limitation of TAM is that it assumes usage is volitional, that is, there are no barriers that would prevent an individual from using an IS if he or she chose to do so This research extends TAM by adding perceived user resources to the model, with careful attention to placing the construct in TAM's existing nomological structure In contrast to measures of self-efficacy and perceived behavioral control that concentrate on how well individuals perceive they can execute specific courses of action, this paper examines perceptions of adequate resources that can facilitate or inhibit such behaviors The inclusion of both a formative and reflective set of measures provides the opportunity for the researcher and manager to decide whether to evaluate only the overall perceptions of adequate resources or also the specific underlying causes The extended model incorporating these measures was then tested in the field The results confirmed that perceived user resources is a valuable addition to the model

1,164 citations


Journal ArticleDOI
TL;DR: In this paper, the Lagrange-multiplier-based fictitious domain methods are combined with finite element approximations of the Navier-Stokes equations occurring in the global model to simulate incompressible viscous fluid flow past moving rigid bodies.

982 citations


Journal ArticleDOI
TL;DR: In this article, a model of cross-functional project groups was developed and hypotheses were tested in a study of 93 research and new product development groups from four companies, and the results showed that functio...
Abstract: A model of cross-functional project groups was developed and hypotheses were tested in a study of 93 research and new product development groups from four companies. The results showed that functio...

676 citations


Journal ArticleDOI
TL;DR: The authors investigated the role money attitudes and credit card use play in compulsive buying within a sample of American college students and found that the money attitudes power prestige, distrust, and anxiety, and that credit card usage often moderates these relationships.
Abstract: The consumer culture has evolved into one of the most powerful forces shaping individuals and societies (Roberts and Sepulveda 1999 a, b). The desire to become a member of the consumer culture appears to be universal (Droge and Mackoy 1995). Changing attitudes toward money are an important catalyst behind the spread of the consumer culture. Money is important—especially to American college students who have been raised in a credit card society where debt is used freely (Ritzer 1995). Schor (1998) believes that access to easy credit is one of the causes of overspending. Using a causal modeling approach, the present study investigated the role money attitudes and credit card use play in compulsive buying within a sample of American college students (see Figure 1). Findings suggest that the money attitudes powerprestige, distrust, and anxiety (Yamauchi and Templer 1982) are closely related to compulsive buying and that credit card use often moderates these relationships. Study results have important public policy, marketing, and research implications.

636 citations


Journal ArticleDOI
TL;DR: In this paper, the authors provided the basis for an incremental restoration of the Himalayan fold-thrust belt in western Nepal using regional mapping, stratigraphic study, and 40Ar/39Ar geochronology.
Abstract: Regional mapping, stratigraphic study, and 40Ar/39Ar geochronology provide the basis for an incremental restoration of the Himalayan fold-thrust belt in western Nepal. Tectonostratigraphic zonation developed in other regions of the Himalaya is applicable, with minor modifications, in western Nepal. From south to north the major structural features are (1) the Main Frontal thrust system, comprising the Main Frontal thrust and two to three thrust sheets of Neogene foreland basin deposits; (2) the Main Boundary thrust sheet, which consists of Proterozoic to early Miocene, Lesser Himalayan metasedimentary rocks; (3) the Ramgarh thrust sheet, composed of Paleoproterozoic low-grade metasedimentary rocks; (4) the Dadeldhura thrust sheet, which consists of medium-grade metamorphic rocks, Cambrian-Ordovician granite and granitic mylonite, and early Paleozoic Tethyan rocks; (5) the Lesser Himalayan duplex, which is a large composite antiformal stack and hinterland dipping duplex; and (6) the Main Central thrust zone, a broad ductile shear zone. The major structures formed in a general southward progression beginning with the Main Central thrust in late early Miocene time. Eocene-Oligocene thrusting in the Tibetan Himalaya, north of the study area, is inferred from the detrital unroofing record. On the basis of 40Ar/39Ar cooling ages and provenance data from synorogenic sediments, emplacement of the Dadeldhura thrust sheet took place in early Miocene time. The Ramgarh thrust sheet was emplaced between ∼15 and ∼10 Ma. The Lesser Himalayan duplex began to grow by ∼10 Ma, simultaneously folding the north limb of the Dadeldhura synform. The Main Boundary thrust became active in latest Miocene-Pliocene time; transport of its hanging wall rocks over an ∼8-km-high footwall ramp folded the south limb of the Dadeldhura synform. Thrusts in the Subhimalayan zone became active in Pliocene time. The minimum total shortening in this portion of the Himalayan fold-thrust belt since early Miocene time (excluding the Tibetan zone) is ∼418–493 km, the variation depending on the actual amounts of shortening accommodated by the Main Central and Dadeldhura thrusts. The rate of shortening ranges between 19 and 22 mm/yr for this period of time. When previous estimates of shortening in the Tibetan Himalaya are included, the minimum total amount of shortening in the foldthrust belt amounts to 628–667 km. This estimate neglects shortening accommodated by small-scale structures and internal strain and is therefore likely to fall significantly below the actual amount of total shortening.

548 citations


Journal ArticleDOI
TL;DR: The cases suggest that a pattern of alignment may continue over a long period, because either the level of alignment is high or the managers do not recognize the low alignment as a problem, and the punctuated equilibrium model provides a valuable perspective for viewing these dynamics.
Abstract: Several prior articles have emphasized the importance of alignment between business and information system (IS) strategies, and between business and IS structures. Seeking to advance our understanding of alignment, we examine the dynamics of changes in alignment through strategy/structure interactions in the business and IS domains. More specifically, we address the following question:In what ways does alignment evolve over time? Changes in the strategic IS management profile (which includes business strategy, IS strategy, business structure, and IS structure) over time are examined using a punctuated equilibrium model, involving long periods of relative stability, or evolutionary change, interrupted by short periods of quick and extensive, or revolutionary, change. Case studies of changes in business and IS strategies and structure over long time periods in three organizations suggest that the punctuated equilibrium model provides a valuable perspective for viewing these dynamics.The cases suggest that a pattern of alignment may continue over a long period, because either the level of alignment is high or the managers do not recognize the low alignment as a problem. Revolutions, involving changes in most or all dimensions of the strategic IS management profile, interrupt the evolutionary changes. However, organizations hesitate to make such revolutionary changes in strategic IS management profiles. Complete revolutions apparently require a combination of strong triggers. Finally, post-revolution adjustments to one dimension of the strategic IS management profile seem to follow revolutionary changes.

522 citations


Journal ArticleDOI
TL;DR: This paper developed a framework for modeling the inter-relationships between GDP growth rates and explanatory variables by re-examining the life expectancy-income relationship and computed confidence intervals for the effect of ASR on growth rate and applied a test for parameter stability.

513 citations


Journal ArticleDOI
TL;DR: This article conducted an over-the-telephone factorial experiment with 1,663 white Americans and found that Asian and Hispanic neighborhood composition do not matter to whites, but black neighborhood composition does matter to white Americans.
Abstract: Employing an alternative methodology and new data, the authors address the debate concerning the underlying causes of racial residential segregation. Are white Americans avoiding racially mixed neighborhoods because they do not want to live with nonwhites? And if so, is this the case independent of factors with which race is associated, such as crime levels or housing values? An over-the-telephone factorial experiment addresses these issues, measuring variables that shape white Americans' choice of purchasing a home. Based on a national, random-digit-dial survey of 1,663 white Americans, the effects of African American, Asian, and Hispanic neighborhood composition on whites' likelihood of buying a house are explored, as well as the other variables for which race may serve as a proxy. Results indicate that Asian and Hispanic neighborhood composition do not matter to whites. Black neighborhood composition, however, does matter, and matters even more for white Americans with children under age 18. The effect of black composition is net of the variables that whites offer as the primary reasons they do not want to live with blacks. The implications of these findings for segregation trends and for future research are considered.

453 citations


Journal ArticleDOI
TL;DR: This paper studies the various planforms that emerge when the model V1 dynamics become unstable under the presumed action of hallucinogens or flickering lights, and shows that the planforms correspond to the axial subgroups of E(2), under the shift-twist action.
Abstract: This paper is concerned with a striking visual experience: that of seeing geometric visual hallucinations. Hallucinatory images were classified by Kluver into four groups called form constants comprising (i) gratings, lattices, fretworks, filigrees, honeycombs and chequer-boards, (ii) cobwebs, (iii) tunnels, funnels, alleys, cones and vessels, and (iv) spirals. This paper describes a mathematical investigation of their origin based on the assumption that the patterns of connection between retina and striate cortex (henceforth referred to as V1)-the retinocortical map-and of neuronal circuits in V1, both local and lateral, determine their geometry. In the first part of the paper we show that form constants, when viewed in V1 coordinates, essentially correspond to combinations of plane waves, the wavelengths of which are integral multiples of the width of a human Hubel-Wiesel hypercolumn, ca. 1.33-2 mm. We next introduce a mathematical description of the large-scale dynamics of V1 in terms of the continuum limit of a lattice of interconnected hypercolumns, each of which itself comprises a number of interconnected iso-orientation columns. We then show that the patterns of interconnection in V1 exhibit a very interesting symmetry, i.e. they are invariant under the action of the planar Euclidean group E(2)-the group of rigid motions in the plane-rotations, reflections and translations. What is novel is that the lateral connectivity of V1 is such that a new group action is needed to represent its properties: by virtue of its anisotropy it is invariant with respect to certain shifts and twists of the plane. It is this shift-twist invariance that generates new representations of E(2). Assuming that the strength of lateral connections is weak compared with that of local connections, we next calculate the eigenvalues and eigenfunctions of the cortical dynamics, using Rayleigh-Schrodinger perturbation theory. The result is that in the absence of lateral connections, the eigenfunctions are degenerate, comprising both even and odd combinations of sinusoids in straight phi, the cortical label for orientation preference, and plane waves in r, the cortical position coordinate. 'Switching-on' the lateral interactions breaks the degeneracy and either even or else odd eigenfunctions are selected. These results can be shown to follow directly from the Euclidean symmetry we have imposed. In the second part of the paper we study the nature of various even and odd combinations of eigenfunctions or planforms, the symmetries of which are such that they remain invariant under the particular action of E(2) we have imposed. These symmetries correspond to certain subgroups of E(2), the so-called axial subgroups. Axial subgroups are important in that the equivariant branching lemma indicates that when a symmetrical dynamical system becomes unstable, new solutions emerge which have symmetries corresponding to the axial subgroups of the underlying symmetry group. This is precisely the case studied in this paper. Thus we study the various planforms that emerge when our model V1 dynamics become unstable under the presumed action of hallucinogens or flickering lights. We show that the planforms correspond to the axial subgroups of E(2), under the shift-twist action. We then compute what such planforms would look like in the visual field, given an extension of the retinocortical map to include its action on local edges and contours. What is most interesting is that, given our interpretation of the correspondence between V1 planforms and perceived patterns, the set of planforms generates representatives of all the form constants. It is also noteworthy that the planforms derived from our continuum model naturally divide V1 into what are called linear regions, in which the pattern has a near constant orientation, reminiscent of the iso-orientation patches constructed via optical imaging. The boundaries of such regions form fractures whose points of intersection correspond to the well-known 'pinwheels'. To complete the study we then investigate the stability of the planforms, using methods of nonlinear stability analysis, including Liapunov-Schmidt reduction and Poincare-Lindstedt perturbation theory. We find a close correspondence between stable planforms and form constants. The results are sensitive to the detailed specification of the lateral connectivity and suggest an interesting possibility, that the cortical mechanisms by which geometric visual hallucinations are generated, if sited mainly in V1, are closely related to those involved in the processing of edges and contours.

Journal ArticleDOI
TL;DR: In this paper, the authors provide evidence that the documented abnormal returns and changes in short interest around option listings are consistent with the mitigation of short sale constraints resulting from the option introduction, and that both the abnormal return and short interest changes around listing dates can be predicted using ex ante characteristics of the underlying stock.
Abstract: Early studies find that option introductions tend to raise the price of underlying stocks. More recent research indicates that post-1980 option introductions are associated with negative abnormal returns in underlying stocks. Other studies document increased short sale activities following option listing. This paper provides evidence that the documented abnormal returns and changes in short interest around option listings are consistent with the mitigation of short sale constraints resulting from the option introduction, and that both the abnormal returns and short interest changes around listing dates can be predicted using ex ante characteristics of the underlying stock.

Journal ArticleDOI
Guojun Wu1
TL;DR: In this article, the authors developed an asymmetric volatility model where dividend growth and dividend volatility are the two state variables of the economy, allowing both the leverage effect and the volatility feedback effect, the two popular explanations of the asymmetry.
Abstract: Volatility in equity markets is asymmetric: contemporaneous return and conditional return volatility are negatively correlated. In this paper we develop an asymmetric volatility model where dividend growth and dividend volatility are the two state variables of the economy. The model allows both the leverage effect and the volatility feedback effect, the two popular explanations of the asymmetry. The model is estimated by the simulated method of moments. We find that both the leverage effect and the volatility feedback are important determinants of asymmetric volatility, and volatility feedback is significant both statistically and economically.

Journal ArticleDOI
01 Nov 2001
TL;DR: The goal of the Grid Application Development Software (GrADS) project is to simplify distributed heterogeneous computing in the same way that the World Wide Web simplified information sharing over the Internet.
Abstract: Advances in networking technologies will soon make it possible to use the global information infrastructure in a qualitatively different way--as a computational as well as an information resource. As described in the recent book The Grid: Blueprint for a New Computing Infrastructure, this Grid will connect the nation's computers, databases, instruments, and people in a seamless web of computing and distributed intelligence, which can be used in an on-demand fashion as a problem-solving resource in many fields of human endeavor--and, in particular, science and engineering. The availability of grid resources will give rise to dramatically new classes of applications, in which computing resources are no longer localized but, rather, distributed, heterogeneous, and dynamic; computation is increasingly sophisticated and multidisciplinary; and computation is integrated into our daily lives and, hence, subject to stricter time constraints than at present. The impact of these new applications will be pervasive, ranging from new systems for scientific inquiry, through computing support for crisis management, to the use of ambient computing to enhance personal mobile computing environments. To realize this vision, significant scientific and technical obstacles must be overcome. Principal among these is usability. The goal of the Grid Application Development Software (GrADS) project is to simplify distributed heterogeneous computing in the same way that the World Wide Web simplified information sharing over the Internet. To that end, the project is exploring the scientific and technical problems that must be solved to make it easier for ordinary scientific users to develop, execute, and tune applications on the Grid. In this paper, the authors describe the vision and strategies underlying the GrADS project, including the base software architecture for grid execution and performance monitoring, strategies and tools for construction of applications from libraries of grid-aware components, and development of innovative new science and engineering applications that can exploit these new technologies to run effectively in grid environments.

Journal ArticleDOI
01 Jan 2001
TL;DR: In this paper, the authors examined the health benefits of leanness and the hazards of obesity while simultaneously considering cardiorespiratory fitness and body fatness and found that being fit may reduce the hazard of obesity.
Abstract: Background: Cardiorespiratory fitness and body fatness are both related to health, but their interrelation to all-cause and cardiovascular disease (CVD) mortality is unknown. Objective: We examined the health benefits of leanness and the hazards of obesity while simultaneously considering cardiorespiratory fitness. Design: This was an observational cohort study. We followed 21925 men, aged 30-83 y, who had a body-composition assessment and a maximal treadmill exercise test. There were 428 deaths (144 from CVD, 143 from cancer, and 141 from other causes) in an average of 8 y of follow-up (176742 man-years). Results: After adjustment for age, examination year, cigarette smoking, alcohol intake, and parental history of ischemic heart disease, unfit (low cardiorespiratory fitness as determined by maximal exercise testing), lean men had double the risk of all-cause mortality of fit, lean men (relative risk: 2.07: 95% Cl: 1.16, 3.69; P = 0.01). Unfit, lean men also had a higher risk of all-cause and CVD mortality than did men who were fit and obese. We observed similar results for fat and fat-free mass in relation to mortality. Unfit men had a higher risk of all-cause and CVD mortality than did fit men in all fat and fat-free mass categories. Similarly, unfit men with low waist girths (<87 cm) had greater risk of all-cause mortality than did fit men with high waist girths (≥99 cm). ). Conclusions: The health benefits of leanness are limited to fit men, and being fit may reduce the hazards of obesity.

Journal ArticleDOI
TL;DR: In this paper, the mesoscale structure and the strength of polymer-nanoparticle interactions have been investigated using viscoelastic measurements of layered silicate-based polymer nanocomposites.
Abstract: Layered silicate based polymer nanocomposites have gained significant technological interest because of the recent commercialization of nylon 6 and polypropylene based materials. Aside from the natural interests in understanding and improving the processing of these hybrids, viscoelastic measurements have also proven to be a sensitive tool to probe the mesoscale structure and the strength of polymer–nanoparticle interactions.

Journal ArticleDOI
TL;DR: The authors showed empirically that regions with a more specialized production structure exhibit output fluctuations that are less correlated with those of other regions (less'symmetric' fluctuations) combined with the causal relation running from capital market integration to regional specialization found in an earlier study.

Journal Article
TL;DR: PhNR amplitudes in POAG patients are smaller than those of normal subjects, and there is a potential role for the PhNR in early detection and possibly in monitoring the progression of glaucomatous damage.
Abstract: PURPOSE. To determine whether the photopic negative response (PhNR) of the electroretinogram (ERG) is reduced in patients with primary open angle glaucoma (POAG). METHODS. ERGs were recorded with DTL electrodes from 62 normal subjects (16 to 82 years), 18 POAG patients (47 to 83 years) and 7 POAG suspects (46 to 73 years) to brief flashes (<6 ms), and also in a few subjects to long (200 ms) red, full-field ganzfeld flashes delivered on a rod-saturating blue background. At the time of ERG measurements, the intraocular pressures of most of the patients were controlled medically. Visual field sensitivities were measured with the Humphrey C24-2 threshold test and optic nerve head cup-to-disc ratio (C/D) was determined by binocular indirect ophthalmoscopy. RESULTS. ERGs of normal subjects contained a slow negative potential following the a- and b-waves, the PhNR, that increased slightly in latency with age. The a- and b-wave amplitudes and implicit times of POAG patients were similar to age-matched controls. In contrast, their PhNRs were small or virtually absent. PhNR amplitudes were reduced even when visual sensitivity losses were small, and were correlated significantly (P < 0.05) with mean deviation (MD), corrected pattern SD (CPSD), and C/D across the population of POAG patients whose MD losses ranged from 1 to 13 dB, CPSDs from 0 to 11 dB and C/Ds from 0.6 to 0.9. PhNRs of most POAG suspects also were small. CONCLUSIONS. PhNR amplitudes in POAG patients are smaller than those of normal subjects. PhNR amplitudes are reduced when visual field sensitivity losses are mild and become even smaller as sensitivity losses increase. There is a potential role for the PhNR in early detection and possibly in monitoring the progression of glaucomatous damage.

Journal ArticleDOI
TL;DR: It is found that crowding exhibits spatial-tuning functions likemasking, but with generally broader bandwidths than those for masking, and that the magnitude of crowding increases monotonically with contrast ratio.

Journal ArticleDOI
17 May 2001-Nature
TL;DR: It is shown that CRY contributes to oscillator function and physiological output rhythms in the antenna during and after entrainment to light–dark cycles and after photic input is eliminated by entraining flies to temperature cycles, indicating fundamental differences between central and peripheral oscillator mechanisms in Drosophila.
Abstract: Cryptochromes are flavin/pterin-containing proteins that are involved in circadian clock function in Drosophila and mice. In mice, the cryptochromes Cry1 and Cry2 are integral components of the circadian oscillator within the brain and contribute to circadian photoreception in the retina. In Drosophila, cryptochrome (CRY) acts as a photoreceptor that mediates light input to circadian oscillators in both brain and peripheral tissue. A Drosophila cry mutant, cryb, leaves circadian oscillator function intact in central circadian pacemaker neurons but renders peripheral circadian oscillators largely arrhythmic. Although this arrhythmicity could be caused by a loss of light entrainment, it is also consistent with a role for CRY in the oscillator. A peripheral oscillator drives circadian olfactory responses in Drosophila antennae. Here we show that CRY contributes to oscillator function and physiological output rhythms in the antenna during and after entrainment to light-dark cycles and after photic input is eliminated by entraining flies to temperature cycles. These results demonstrate a photoreceptor-independent role for CRY in the periphery and imply fundamental differences between central and peripheral oscillator mechanisms in Drosophila.

Journal ArticleDOI
TL;DR: This article analyzed party discipline in the House of Representatives between 1947 and 1998 and found that the Snyder-Groseclose method of estimating the influence of party discipline is biased toward exaggerating party effects.
Abstract: TTT e analyze party discipline in the House of Representatives between 1947 and 1998. The effects of 1/V/ party pressures can be represented in a spatial model by allowing each party to have its own cutting line on roll call votes. Adding a second cutting line makes, at best, a marginal improvement over the standard single-line model. Analysis of legislators who switch parties shows, however, that party discipline is manifest in the location of the legislator's ideal point. In contrast to our approach, we find that the Snyder-Groseclose method of estimating the influence of party discipline is biased toward exaggerating party effects.

Journal ArticleDOI
TL;DR: The effect of coherence resonance in a heterogeneous array of coupled Fitz Hugh-Nagumo neurons is demonstrated and it is shown that coupling of such elements leads to a significantly stronger coherence compared to that of a single element.
Abstract: We demonstrate the effect of coherence resonance in a heterogeneous array of coupled Fitz Hugh--Nagumo neurons. It is shown that coupling of such elements leads to a significantly stronger coherence compared to that of a single element. We report nontrivial effects of parameter heterogeneity and spatial independence of noise on array-enhanced coherence resonance; especially, we find that (i) the coherence increases as spatial correlation of the noise decreases, and (ii) inhomogeneity in the parameters of the array enhances the coherence. Our results have the implication that generic heterogeneity and background noise can play a constructive role to enhance the time precision of firing in neural systems.

Journal ArticleDOI
TL;DR: Results suggest that although face-name training, spaced retrieval, and cognitive stimulation may produce small gains in learning personal information and on a measure of attention, improvement does not generalize to overall neuropsychologic functioning or patient quality of life.
Abstract: The efficacy of a cognitive intervention consisting of training in face-name associations, spaced retrieval, and cognitive stimulation was tested in a sample of 37 patients (16 men, 21 women) with probable Alzheimer disease (AD). Patients with AD were randomly assigned to receive either the cognitive intervention or a mock (placebo) intervention for 5 weeks. The placebo group then crossed over to receive the intervention. During the intervention, AD patients showed significant improvement in recall of personal information, face-name recall, and performance on the Verbal Series Attention Test. Improvement did not generalize to additional neuropsychologic measures of dementia severity, verbal memory, visual memory, word generation, or motor speed, or to caregiver-assessed patient quality of life. Results suggest that although face-name training, spaced retrieval, and cognitive stimulation may produce small gains in learning personal information and on a measure of attention, improvement does not generalize to overall neuropsychologic functioning or patient quality of life.

Journal ArticleDOI
01 Dec 2001-Polymer
TL;DR: In this paper, the influence of nanodispersed montmorillonite layers and process history on the crystal structure of nylon 6 between room temperature and melting was examined with simultaneous small-and wide-angle X-ray scattering and modulated differential scanning calorimetry.

Journal ArticleDOI
TL;DR: In this paper, a meta-analysis investigated the available empirical literature, identifying 16 studies for expatriate adjustment (total n = 2270) and 25 studies for ex-patriate performance ( total n = 2490).
Abstract: Corporations are increasingly relying on cross-cultural training of expatriate managers to reduce personnel costs. Previous research has shown consistent validity for different training methods. This meta-analysis investigated the available empirical literature, identifying 16 studies for expatriate adjustment (total n = 2270) and 25 studies for expatriate performance (total n = 2490). Mean effect sizes were lower than in a previously published meta-analysis and were significantly different from zero for both performance (r = .26) and adjustment (r = .13). Until the effects of potential moderators are better understood, prescriptions for cross-cultural training design should be made cautiously.

Journal ArticleDOI
TL;DR: A detailed analysis of the spatial arrangement of L, M and S cones in the living eyes of two humans and one monkey using statistical methods that characterize the arrangement of each type of cone in the mosaic of photoreceptors.

Journal ArticleDOI
TL;DR: In this paper, the authors developed a suite of new seismic attributes that reduce the input 20-60 running window spectral components down to a workable subset that allows them to quickly map thin-bed tuning effects in three dimensions.
Abstract: Running window seismic spectral decomposition has proven to be a very powerful tool in analyzing difficult‐to‐delineate thin‐bed tuning effects associated with variable‐thickness sand channels, fans, and bars along an interpreted seismic horizon or time slice. Unfortunately, direct application of spectral decomposition to a large 3‐D data set can result in a rather unwieldy 4‐D cube of data. We develop a suite of new seismic attributes that reduces the input 20–60 running window spectral components down to a workable subset that allows us to quickly map thin‐bed tuning effects in three dimensions. We demonstrate the effectiveness of these new attributes by applying them to a large spec survey from the Gulf of Mexico. These two thin‐bed seismic attributes provide a fast, economic tool that, when coupled with other attributes such as seismic coherence and when interpreted within the framework of geomorphology and sequence stratigraphy, can help us quickly evaluate large 3‐D seismic surveys. Ironically, in a...

Journal ArticleDOI
TL;DR: In this paper, the authors use weekly stock market data for a group of Latin American countries to analyze the behavior of volatility through time and find strong evidence of volatility co-movements across countries, especially among the Mercosur countries.

Journal ArticleDOI
TL;DR: The stability and the induced L"2 norm performance of these systems using parameter-dependent Lyapunov functionals are explored and the design of parameter- dependent state-feedback controllers that guarantee desired L" 2 gain performance is examined.

Journal ArticleDOI
TL;DR: In this paper, the authors focus on studies determining whether and how much changes in net worth, such as those generated by the stock-market boom in the U.S. over the latter 1990s, are responsible for subsequent changes in the growth rate of consumer spending.
Abstract: This paper reviews the statistical approach typically applied by macroeconomi sts to investigate the empirical link between aggregate data on household consumption, income, and wealth. In particular, we focus on studies determining whether and how much changes in net worth, such as those generated by the stock-market boom in the U.S. over the latter 1990s, are responsible for subsequent sw ings in the growth rate of consumer spending. We show how simple economic theory is used to motivate an econometric strategy that consists of two stages of analysis. First, regress ions are used to identify trend mov ements shared by consumption, income, and wealth over the long run, then deviations of these series from their common long-run trends are used to help forecast consumption growth over the short run. Our discussion highlights the various judgments that researchers must make in the course of impl ementing this empirical approach, and we detail how specific parameter estimates describing the magnitude of the wealth effect on consumption--and even broad conclusions about its existence --are affected by making alternative choices.