bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Fully Coupled Constitutive Model for Electrostrictive Ceramic Materials
Authors: Hom Craig L. , Shankar Natarajan 
Published: March 2007

A three-dimensional, electromechanical constitutive law has been formulated for electrostrictive ceramic materials. This fully coupled, phenomenological model relates the key state variables of stress, strain, electric field, polarization and temperature in a set of compact nonlinear equations. The direct and converse electrostrictive effects are modeled by assuming that the electri cally induced strain depends on second-order polarization terms. In addition, a simple empirical relationship for the dielectric behavior is used to model the saturation of the induced polarization with increasing electric field. Unlike previous electrostrictive constitutive laws based on polynomial expansions, this consti tutive law depends on a manageable number of material constants. As an example, material constants for the model were determined from induced strain and dielectic data for a relaxor-ferroelectric based on lead magnesium niobate, Pb(Mg1/3Nb2/3)O 3-PbTiO3-BaTiO3 (PMN-PT-BT). Finally, pre dictions of the material's mechanical behavior under constant electric field and its electrical behavior under constant applied stress are made.
Affordances. Motivations, and the World Graph Theory
Authors: Guazzelli Alex , Bota Mihail , Corbacho Fernando J. , Arbib Michael A. 
Published: March 2007

O'Keefe and Nadel (1978) distinguish two paradigms for navigation, the "locale system" for map-based navigation and the "taxon (behavioral orientation) system" for route navigation. This article models the taxon system, the map-based system, and their interaction, and argues that the map-based system involves the interaction of hippocampus and other systems. We relate taxes to the notion of an affordance. Just as a rat may have basic taxes for approaching food or avoiding a bright light, so does it have a wider repertoire of affordances for possible actions associated with immediate sensing of its environment. We propose that affordances are extracted by the rat posterior parietal cortex, which guides action selection by the premotor cortex and is influenced also by hypothalamic drive information. The taxon-affordances model (TAM) for taxon-based determination of movement direction is based on models of frog detour behavior, with expectations of future reward implemented using reinforcement learning. The specification of the direction of movement is refined by current affordances and motivational information to yield an appropriate course of action. The world graph (WG) theory expands the idea of a map by developing the hypothesis that cognitive and motivational states interact. This article describes an implementation of this theory, the WG model. The integrated TAM-WG model then allows us to explain data on the behavior of rats with and without fornix lesions, which disconnect the hippocampus from other neural systems.
The Short Form of the Task-Specific Occupational Self-Efficacy Scale
Authors: Osipow Samuel H. , Temple Richard D. , Rooney Rebecca A. 
Published: March 2007

Occupationally relevant skills were selected from the 66 GOE Categories of the Selected Characteristics of Occupations Defined in the Dictionary of Occupational Titles (U.S. Department of Labor, 1981). These skills were then translated into items and reduced to 230 self-efficacy statements. Subjects were asked to respond to each item in terms of their confidence in their ability to perform the task. Test-retest reliability for the 230 items was .77 over a 2- to 3- week period. The responses of 1,265 subjects were factor analyzed using a principle components method and promax rotation. The result was four, clean, non-overlapping factors. By eliminating some items, the instrument was reduced to a 60-item scale with four, 15 item subscales reflecting the four factors. Factor 1 describes language and interpersonal skills; factor 2 emphasizes quantitative, logical, scientific, and business skills; factor 3 describes physical strength and agility; factor 4 reflects aesthetic skills. Cronbach-Alphas describing internal consistency for the four resulting scales are all above .90, as is test-retest reliability over a 2-week period. In addition, intercorrelation matrices for the four factors are reported here.
Howie Davis Introduces Mrs. Swanson
Authors: Funke Arthur S. 
Published: March 2007

The state director and some of his staff of the Minnesota Mental Illness, Mental Retardation Inebriacy (Mental Health) Program were dissatisfied with the status of the State Hospital Program, the Community Mental Health Program, the Mental Health Programs of the County Welfare Departments and the Central Office, and they decided to define and address these dissatisfactions. Howie Davis provided major doses of the energy and thought involved in these efforts. Included in the concerns about the status of these programs were the following : (a) What were the social purposes that these programs were intended to be instrumental in promoting or achieving? (b) How could these social purposes be identified by the Central Office? (c) How could staff from each of the above major program components participate in the process from the beginning? (d) How could the extent to which each program was fulfilling its social purposes be determined? (e) How could the success of each program in fulfilling its purposes be increased? Application was made to NIMH for a grant to support the effort. When the application was approved, I was recruited as the Project Director. I arrived in July 1962 only to learn that Howie was soon to be leaving Minnesota for a job with NIMH. Howie and I had known each other for a number of years as the Chief Psychologists in our respective states. Now we could brag that with the two of us, Minnesota had the biggest psychology staff in the 50 states!
The Kraken Wakes: corporate social responsibility and the political dynamics of the hazardous waste issue
Authors: Smith Denis 
Published: March 2007

Smith D., 1991. The Kraken Wakes: corporate social responsibility and the political dynamics of the hazardous waste issue. Industrial Crisis Quarterly, 5: 189-207. The issue of hazardous waste disposal has assumed international importance since the Karin B episode propelled it fully onto the global political agenda. This paper seeks to examine the transfers of such waste streams by reference to the issues of corporate responsibility and the role of technical expertise within environmental debates. The paper examines two cases, namely the Karin B / Nigeria waste dumping episode (1988) and the export of Canadian PCB waste to the UK (1989), in an attempt to assess the notions of equity in environmen tal conflicts. Within this context the role of technical expertise will be exam ined in an attempt to assess its impact within the framework of corporate re sponsibility for hazardous waste disposal.
Measured Soil Thermal Conductivities and Modified Design Curves for Predicting Frost Penetration Adjacent to Insulated Foundations
Authors: Figley D.A. , Snodgrass L.J. 
Published: March 2007

Methods for predicting frost penetrations are necessary when foundations are placed on frost susceptible soils if problems with frost heave are to be avoided. Graphical methods exist for predicting frost penetration for unheated foundations, however, design information for heated foundations is very limited Insulation levels on heated foundations will affect the heat loss to the surrounding soil and hence the depth of frost penetration. The paper presents long term measured frost penetration and soil conductivity data for four typical heated residential foundations. Graphical relationships (modified design curves) between frost depths and freezing indices are presented and compared with open field (unheated) conditions.
A Computer Analysis of the Annual Thermal Performance of a Roof System with Slightly Wet Fibrous Glass Insulation under Transient Conditions
Authors: Pedersen Carsten R. , Courville George E. 
Published: March 2007

Field and laboratory results from short-term summer tests have sug gested that small amounts of moisture in fibrous glass roof insulations can have a sig nificant effect on the dynamic thermal performance of roof systems. These results have been reproduced using the transient heat and mass transfer mathematical model. Subsequently, the model has been used to simulate roof performance in different seasons and in different climate regions. In all cases the effects continue to be signifi cant. Small amounts of water readily move up or down in the insulation depending on the direction of the vapor pressure gradient. If a large amount of water is present, it concentrates on the bottom during the summer and on the top during the winter. In addition, during most days there is a portion that cycles up and down This adds excess heat to the building during the warm afternoon which may increase the air conditioning load and removes nearly the same amount of extra heat during the cool evening which may increase the building's heating system load The results from the model calculations are reported in terms of increased cooling and increased heating. Combining these into a changed building energy load and discussing the impact on building performance requires additional analysis to show how these hourly changes impact the whole building's energy balance Using the available property data for other roofing insulations indicates that this latent heat effect is not as important as it is for fibrous glass insulation Additional computer simulations with the model suggest that the effect is notice able even for moisture concentrations at a level which can be picked up by insulations in outdoor storage Impermeable layers between insulation boards influence the magnitude of dynamic heat transfer but do not eliminate it. Calculations show that thermal performance for new roofs over old insulation where moisture is probably common may be particularly affected by these results.
Performance Based Procurement System for Roofing
Authors: Kashiwagi Dean T. 
Published: March 2007

This paper presents research performed at the Del E. Webb School of Construction on a new performance based procurement system for roofing. This procurement system will assist suppliers, manufacturers, and roofing contractors in the continuous improvement of their products and services, and enhance the stability of the roofing industry. The author shows that by using selected methods of infor mation management, e.g., a relative distancing model based on "fuzzy logic," the fa cility managers can select both the roofing system and the roofing contractor with a proven track record and ensure a high probability that the roof will perform over a required service-period. The performance based procurement system presented in this paper is used to eval uate alternative technical solutions. This procurement system can be applied not only to the roofing contractors but, also, to general contractors, Job Order contractors, mechanical contractors, material suppliers, and even to the manufacturers. This pro gram is being currently verified under a joint project with the Alliance of Construc tion Excellence and involves facility owners and managers from various companies such as Motorola, Honeywell, Morrison Knudson, IBM, and other major facilities in the Phoenix metropolitan area.
The relation between brain iron and NMR relaxation times: An in vitro study
Authors: Vymazal Josef , Brooks Rodney A. , Baumgarner Charles , Tran Vu , Katz David , Bulte Jeff W. M. , Bauminger E. Rivka , Chiro Giovanni Di 
Published: March 2007

AbstractT1 and T2 relaxation times and iron concentrations were measured in 24 specimens of gray matter from fresh human and monkey brains at magnetic fields from 0.05 to 1.5 Tesla. Three different effects were found that correlate with iron content: a T1‐shortening that falls off somewhat at high fields, a T2‐shortening that is field‐independent and thus important at low fields, and a contribution to 1/T2 that increases linearly with field strength. This linear field dependence has been seen only in ferritin and other ferric oxyhydroxide particles. Our results are in agreement with in vivo MRI studies and are generally consistent with values for ferritin solution, except for differences such as clustering of ferritin in tissue. A cerebral cavernous hemangioma specimen showed similar T2‐shortening, but with a 2.7 times larger magnitude, attributed to larger clusters of hemosiderin in macrophages. The dependence on interecho time 2T was measured in three brains; 1/T2 increased significantly for T up to 32 ms, as expected from the size of the ferritin clusters. These findings support the theory that ferritin iron is the primary determinant of MRI contrast in normal gray matter.
Diffusion weighted fMRI at 1.5 T
Authors: Song Allen W. , Wong Eric C. , Tan Steve G. , Hyde James S. 
Published: March 2007

AbstractFunctional magnetic resonance imaging (fMRI) is capable of detecting task‐induced blood oxygenation changes using susceptibility sensitive pulse sequences such as gradient‐recalled echo‐planar imaging (EPI). The local signal increases seen in the time course are believed to be due to an increase in oxygen delivery that is incommensurate with oxygen demands. To help isolate the sources of functional signal changes, the authors have incorporated various forms of diffusion weighting Into EPI pulse sequences to characterize the apparent mobility of the functionally modulated protons. Results suggest that the majority of the functional signal at 1.5 T arises from protons that have apparent diffusion coefficients that are approximately four or five times higher than that of brain tissue. This implies that significant functional signal sources are either protons within the vascular space or protons from the perivascular space that is occupied by cerebro‐spinal fluid.
Effect of repetitive ischemia on myocardial oxygen tension in isolated perfused and hypoperfiised rat hearts
Authors: Friedman Bruce J. , Grinberg Oleg Y. , Isaacs Kimberly A. , Ruuge Enno K. , Swartz Harold M. 
Published: March 2007

AbstractThe objective of this study was to determine the effects of repetitive ischemia on myocardial oxygen tension (pO2), consumption, and delivery in crystalloid normoperfused (perfu‐sion pressure > 70 mmHg) and hypoperfused (perfusion pressure ˜50 mmHg) constant flow isolated rat hearts. EPR oximetry with lithium phthalocyanine was used to measure myocardial pO2. Baseline myocardial pO2 (means ± SE) was 185 ± 13 mmHg (normoperfused) and 162 ± 14 mmHg (hypoperfused). Myocardial pO2 fell to <1 mmHg during no‐flow ischemia. After recovery from repetitive ischemia, myocardial pO2 and coronary resistance increased significantly in all hearts; oxygen consumption and left ventricle work decreased in normoperfused hearts, although not significantly compared with controls, and did not change significantly in hypoperfused hearts. Increased myocardial pO2 in the normoperfused group may be due to decreased oxygen consumption and/or increased local delivery, while increased myocardial pO2 in the hypoperfused hearts is due to increased local oxygen delivery.
Development and Validation of an Instrument to Identify Self-Directed Continuing Learners
Authors: Oddi Lorys F. 
Published: March 2007

This study sought to describe the personality characteristics of self-directed continuing learners, develop an instrument to identify such learners, and conduct empirical investigations to validate the instrument. Dimensions of the self-directed continuing learner's personality were developed and then used in the construction of an item pool. Prepilot and pilot study results provided the basis for refining the items into a 24-item instrument. When administered to a sample of 271 graduate students, the instrument demonstrated an internal consistency of .87 and a test-retest reliability of .89. Estimates of construct validity were obtained through correlation of scores with measures of educational participation, adult intelligence, self-confidence, endurance, and affiliation; results suggest the instrument is a valid tool for identifying self-directed continuing learners when used in its entirety.
Communitarianism, Vickers, and Revisioning American Public Administration
Authors: ADAMS GUY B. , CATRON BAYARD L. 
Published: March 2007

Classical liberalism and the unrestrained individualism that is of its essence are inappropriate for current ever-increasing interdependence. Recent communitarian thinking in the United States suggests that the exclusive pursuit of private interest is, in fact, inimical in the long run to individual liberty. Sustained policy change depends, however, on a fundamental rethinking of ethics and epistemology; Vickers's concept of appreciation is an important contribution to this task. The authors conclude that there is a need both for more government and for more democracy; greater intrusions on autonomy are inevitable if Western culture in its present form is to survive. The sanest like the maddest of us cling like spiders to a self-spun web, obscurely moored in vacancy and fiercely shaken by the winds of change. Yet this frail web, through which many see only the void, is the one enduring artifact, the one authentic signature of humankind, and its weaving is our prime responsibility. —Geoffrey Vickers “The Psychology of Policymaking and Social Change”
An Analytical Investigation of the Effects of Heterogeneous Regression Slopes in Analysis of Covariance
Authors: Hollingsworth Holly H. 
Published: March 2007

The effects of violation of the assumption of homogeneity of regression on the Type I error rate and on the power of analysis of covariance (ANCOVA) were investigated. The study shows that the test statistic used to test the hypothesis of equal treatment effects has a non-central F-distribution with the non-centrality parameter equal to zero if and only if the regression slopes are homogeneous and/or the means of the covariables, computed on the entire sample, are all zero. Consequently, if the heterogeneous regression slopes are present, the likelihood of committing a Type I error is greater than what the researcher prespecified. The power function of the test of hypothesis was also determined. Results indicated that the power of ANCOVA was effected by heterogeneous regression slopes and furthermore it was found that the test does not maximize the power for all possible differences of the treatment effects as described by the alternative hypothesis. The method of investigation was analytical and the results are general for any number of groups, any combination of group sizes and any number of covariables, provided the number of observations in each group is larger than the number of covariables.
Low Velocity Transverse Normal Impact of Graphite Epoxy Composite Laminates
Authors: Mcquillen Edward J. , Gause Lee W. , Llorens Richard E. 
Published: March 2007

A theoretical-experimental investigation has been conducted to deter mine the response of composite structural elements to low speed, trans verse impact. Experimental results of this investigation showed that as the velocity of impact is increased it requires less impactor kinetic energy to produce damage. A structural dynamic response model consisting of a uniform Bernoulli- Euler beam and a rigid impactor mass was employed. Displacement and velocity distributions were assumed as initial conditions and the solution was expanded in the eigenfunctions of the free vibration problem using Galerkins' method. Good correlation of experimental results with the results of this analyt ical structural dynamic model have been obtained over the velocity range from 0 to 6 m/s.
Hard Object Impact Damage of Metal Matrix Composites
Authors: Awerbuch Jonathan , Hahn H. Thomas 
Published: March 2007

The paper presents results on the damage mechanisms in hard object impact and their effect on the residual tensile strength of unidirectional Boron/Aluminum and Borsic/Titanium composites. The ballistic tests were carried out with 0.177" steel spheres impacting at the center of centilever plates over a velocity range of 50 to 4000 ft/sec. The induced ballistic damage and the different failure modes are examined by radiography and SEM, and the post impact residual tensile strength and residual velocity after perforation are studied for both materials. The damage induced in Boron/Aluminum consists mainly of lateral and axial cracks causing large strength degradation, up to 50 percent of the initial strength. Borsic/Titanium, on the other hand, shows much better impact resistance and the ballistic damage consists of localized plastic de formation and formation of a sheared plug causing strength degradation of 20 percent of the initial strength, as is the case with homogeneous titan ium. An analytical model based on fracture mechanics can predict fairly well the damage size and the residual tensile strength. Ballistic limit velocity and residual velocity after perforation are shown to be predictable by a model developed for homogeneous metallic plates.
Three-Dimensional Analysis of a Postbuckled Embedded Delamination
Authors: Whitcomb John D. 
Published: March 2007

Delamination growth caused by local buckling of a delaminated group of plies was investigated. Delamination growth was assumed to be governed by the strain- energy release rates GI, GII, and GIII. The strain-energy release rates were calculated using a geometrically nonlinear, three-dimensional, finite element analysis. The program is described and several checks of the analysis are discussed. Based on a limited para metric study, the following conclusions were reached: 1. The problem is definitely mixed-mode. In some cases GI is larger than GII ; for other cases the opposite is true. 2. In general, there is a large gradient in the strain-energy release rates along the delamination front. 3. The locations of maximum GI, and GII depend on the delamination shape and the ap plied strain. 4. The mode III component was negligible for all cases considered. 5. The analysis predicted that parts of the delamination would overlap. The results pre sented herein did not impose contact constraints to prevent overlapping. Further work is needed to determine the effects of allowing the overlapping.
Factors Affecting the Transverse Tensile Strength of Unidirectional Continuous Silicon Carbide Fibre Reinforced 6061 Aluminum
Authors: Wisnom Michael R. 
Published: March 2007

A study of the micromechanics of continuous silicon carbide fibre rein forced 6061 aluminum has been carried out using generalised plane strain non-linear finite element analysis. An interface element has been developed enabling separate shear and tensile strengths to be assigned, with a quadratic interaction equation. Residual stresses due to manufacturing were included in the analysis. The effect on transverse tensile strength of fibre packing geometry, fibre spacing, resid ual stresses, interface strengths and matrix material properties were investigated. It was found that the interface strength is the most important factor. Residual stresses are beneficial, these being largely controlled by the yield strength of the matrix material at the time the residual stresses are set up. Fibre packing and spacing and matrix strength do not significantly affect predicted strength.