bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of localized quadratic encoding and reconstruction
Authors: Pipe James G. 
Published: March 2007

AbstractLocalized quadratic (LQ) encoding is a method of collecting multislice MRI data sets with greatly overlapping excited slices in such a way that the slice overlap can be deconvolved. This results in reconstructed data with resolution equal to the center‐to‐center slice spacing, regardless of the amount of excited slice overlap. LQ encoding is analyzed using the modulation transfer function of the encoding and reconstruction process. This allows analysis of many aspects of the technique in a well established theoretical framework. Many different characteristics of the method are explored, including excited slice profiles, required RF magnitudes and specific absorption rate, signal to noise ratio, signal dynamic range, reconstruction artifacts, sensitivity to motion, saturation and inflow effects, modulation transfer function shifting, and off‐resonance artifacts. It is suggested that this technique is best suited for applications currently using multiple thin‐slab three‐dimensional encoding.
Fast dynamic imaging using two reference images
Authors: Hanson Jill M. , Liang Zhi‐Pei , Wiener Erik C. , Lauterbur Paul C. 
Published: March 2007

AbstractThis paper presents a fast dynamic imaging method which is characterized by the acquisition of two high‐resolution reference images and a sequence of low‐resolution dynamic data sets. Image reconstruction is accomplished using a generalized series based algorithm. Experimental results demonstrate that dynamic images with high temporal resolution can be obtained while maintaining excellent spatial resolution. This method will be useful for a variety of dynamic imaging applications including contrast‐enhanced dynamic imaging and functional brain studies.
Spatial mapping of nitric oxide generation in the ischemic heart using electron paramagnetic resonance imaging
Authors: Kuppusamy Periannan , Wang Penghai , Samouilov Alexandre , Zweier Jay L. 
Published: March 2007

AbstractRecently, it has been shown that rat hearts subjected to global ischemia generate nitric oxide (NO) and that a significant portion of it is generated by the reduction of nitrite under the acidic and reducing conditions that occur during myocardial ischemia [Zweier, Wang, Samouilov, Kuppusamy, Nature Med. 1, 804–809 (1995)]. In the present study it is further attempted to map the spatial distributions of the NO generation in the ischemic myocardium using L‐band electron paramagnetic resonance imaging. Rat hearts were loaded with 10 mM nitrite and subjected to global no‐flow ischemia, during which time a series of three‐dimensional spatial electron paramagnetic resonance (EPR) images of the distribution of NO were obtained using the NO trap bis(N‐methyl‐D‐glucamine dithiocarbamate)iron(II). The images clearly showed that NO is formed throughout the myocardium. Kinetic experiments showed that maximum NO generation and trapping occur at the midmyocardium and spread out to endocardium and epicardium of the left ventricle. The magnitude of generation in the RV myocardium is four‐ to fivefold lower than in the LV.
Measurement of the arterial concentration of Gd‐DTPA using MRI: A step toward quantitative perfusion imaging
Authors: Fritz‐Hansen Thomas , Rostrup Egill , Larsson Henrik B. W. , Søndergaard Lars , Ring Poul , Henriksen Ole 
Published: March 2007

AbstractA noninvasive method using an inversion recovery turbo‐FLASH for dynamic measurement of the arterial input function represented by the bolus passage of Gd‐DTPA in the descending aorta is presented, and the results are compared with the input function obtained by arterial blood samples. A good accordance between the two input functions was found, indicating that it is possible to measure the input function to the myocardium using MRI. A variation between the two concentration curves of 5% at upslope, 2.7% at peak point, and <7% at downslope was found. The study also indicates that a short inversion time <250 ms has to be used to ensure correct measurement of peak concentration.
COSESS and INSESS: Coherent and incoherent spin echoes in the steady state
Authors: Werthner Harald , Krieg Robert , Ladebeck Ralf , Saemann‐Ischenko Georg 
Published: March 2007

AbstractA new fast sequence type, called COSESS/INSESS, is described. The steady state for COSESS is coherent but incoherent for INSESS. COSESS/INSESS combine the contrast behavior of fast imaging with steady‐state free precession (FISP) and fast low angle shot (FLASH), respectively, to the robustness of spin‐echo (SE) sequences with regard to susceptibility and field inhomogeneities. In contrast to other fast sequences such as rapid spin‐echo excitation (RASEE), fast low angle spin echo with short echo time (FATE) or the missing pulse sequence, which also uses a spin echo, COSESS/INSESS can additionally handle time‐dependent disturbances arising from eddy currents, hysteresis or Bo instability. The acquisition time is 2 to 3 times longer than with gradientbased steady‐state sequences. The principle of echo generation is evaluated and shows a superposition of several subechoes in the spin echo. Different solutions were elaborated to attain a coherent superposition of sub‐echo signals for COSESS. Signal and contrast behavior were investigated both by simulations and experiments and demonstrate the performance of COSESS/INSESS.
Academic and Behavioral Problems of Boys in Elementary School
Authors: Chapman Robert B. 
Published: March 2007

The development of a boy's sex role begins shortly after birth when he is assigned certain colors due to his gender. By the time the boy is eighteen months old, adults are expecting clear sex differences in his behavior. Subtle and not so subtle pressure is put on the child to produce sex differences. The pressure is from a wide variety of sources such as type of toys purchased, clothing provided, decoration of his room, and his interactions with family members and other significant adults. Consequently the boy's preference for guns, wheeled toys, running, and aggressive play appears at or before age three. By the time the boy enters elementary school at age six, he has a strong notion of the masculine behaviors expected of him. Modification of sex roles to accommodate the expectations of the school is one of the more difficult tasks facing elementary school aged boys. As they enter school, boys are required to assume a second role, that of a student. However, the behaviors implicit in many boys' sex roles are oppositional to the behaviors required in the student role. The conflict results in the boy not successfully assuming the student role, and may result in the boy being identified as having an academic and/or behavioral problem. Considerable research indicates that a large percentage of boys are experiencing difficulties in the schools. The present article will explore the reasons boys are involved in such frequent problems in school, and will make recommendations for persons working with elementary school aged boys.
Correcting for BIAS in the Canonical Redundancy Statistic
Authors: Dawson-Saunders Beth K. 
Published: March 2007

The canonical redundancy statistic, an estimate of the amount of shared variance between two sets of variables, has been proposed as an alternative to the squared canonical correlation coefficient in the interpretation of the results of canonical correlation analysis. The present study was undertaken to investigate the bias of the canonical redundancy statistic and to evaluate methods to correct for any bias. Using Monte Carlo methods, the redundancy statistic was found to exhibit an amount of bias similar to that of the first squared canonical correlation coefficient. Bias is most affected by sample size: bias was observed to decrease by half each time the sample size was doubled. Bias also decreases as the intercorrelations between the two sets of variables increase. The number of predictor and criterion variables, as well as the size of the correlations between variables in each set, have relatively minimal effect on bias. Two formulae, Wherry and Olkin-Pratt, that were developed to estimate the population value of the squared multiple correlation coefficient, were found to correct adequately the bias of the redundancy statistic. As an example of the use and interpretation of canonical redundancy analysis, a set of data relating consumer health values and health behaviors was analyzed. While the results indicate that only a small amount of redundant information is shared between these two sets of measures, the redundancy statistic provides a more conservative interpretation of this overlap than do the squared canonical correlation coefficients.
Toward Uniformity of Clusters Across Methods by Reducing Errors in Data
Authors: McQuitty Louis L. 
Published: March 2007

Iterative Intercolumnar Correlation Classification (IICC) computes the correlation coefficients for the entries of every column of a matrix with those of every other column of the matrix. The procedure is iterated until a matrix is generally realized of only two clusters. Every object of each cluster has an index of plus-one with every other object of its cluster. Indices of minus one only mediate between objects across clusters. IICC probably goes to an extreme. It disallows that any object of a cluster can be less than a perfect respresentative of that cluster. This extreme derives from the definition of a cluster by IICC. The stringency of the definition is reduced. This justifies discontinuing iteration earlier. Both initial indices and those of the middle iteration were clustered by four methods. Iteration increases the size and validity of indices, reduces errors in the indices, and increases homogeneity amongst them. Increased similarity in procedures ensues as at least some methods are adapted to middle-iteration indices. Both the validity of clusters and their similarity across methods are increased. Other sets of data, other methods, and other definitions need to be studied in the above fashion.
Transverse Behavior of Unidirectional Ribbon Reinforced METGLAS® / Epoxy Laminates
Authors: Yeow Y.T. 
Published: March 2007

The finite element method (FEM) is used to model the elastic behavior of an epoxy based, rectangular shaped, metallic glass reinforced composite. Since a microscopic representation is utilized, the effects of reinforcement aspect ratio, volume fraction, amount of overlap and the distance between reinforcement along the width and thickness direction on the macroscopic transverse moduli and strength are determined. Comparisons of the transverse moduli obtained from FEM, the Halpin- Tsai (H-T) equations and experiments are made for laminates containing various combinations of the parameters, mentioned above, The influence of these parameters on the transverse strength are identified.
Residual Strength Prediction of Impacted CFRP Laminates
Authors: Caprino G. 
Published: March 2007

A model for the prediction of residual tensile strength of impacted CFRP laminates is presented and discussed. The damage zone is considered, from the residual strength standpoint, as an equivalent implanted hole, and strength degradation is calculated using a linear elastic fracture mechanics approach previously proposed. The results of experimental tests, carried out at low velocity on AS/3501 (0/±45) 2s laminates, show a good correlation with theoretical predictions; moreover, data available in the literature seem to indicate the effectiveness of the proposed formula in foreseeing the com pressive strength degradation due to impact. The physical meaning of the parameters appearing in the model, together with the data here presented, suggests a method to obtain the residual strength curve as a func tion of impact energy by a minimum number of experimental tests. This method is ex pected to be valid for rate-insensitive materials such as carbon fiber reinforced laminates.
Studies on Lightweight Glass Fibre-Resin Composites by Destructive and Nondestructive Methods
Authors: Järvelä Pentti , Laitinen Keijo W. , Purola Jaakko J. , Törmälä Pertti 
Published: March 2007

The relationship between the structure and properties of very lightweight glasswool- phenolformaldehyde resin composites was studied by measuring the composite strength and elasticity properties. The fibre structure of the examined composite (den sity 10 ... 40 kg/m3 and resin concentration 1 ... 13 w-%) was found to be almost random in two directions, while in the third direction there were relatively few fibres. It was found that the elasticity properties of the composite after compression decrease as a function of time and the degree of compression. This phenomena can be explained by the static fatigue of the glass fibres, which means that their strength depends on the length of time that a load is applied or on the loading rate [1]. It was shown that the values of destructive tests (tensile strength), as well as such material parameters, like density and binder phase concentration are possible to be determined with nondestructive tests (the damping test).
Predicting Crack Growth Direction in Unidirectional Composites
Authors: Gregory M.A. , Herakovich C.T. 
Published: March 2007

The purpose of this study is to gain a better understanding of the parameters affect ing crack growth direction in unidirectional composite materials. To achieve this, the effect of anisotropy and biaxial, far field loading on the direction of crack growth in unidirectional off-axis composite materials is investigated. Specific emphasis is placed on defining the crack tip stress field and finding a consistent criterion for predicting the direction of crack growth. An anisotropic crack tip stress analysis was implemented using three criteria (the normal stress ratio theory, the tensor polynominal failure criterion and the strain energy density theory) to predict the direction of crack extension in unidirectional off- axis graphite-epoxy. The theoretically predicted crack extension directions were then compared with experimental results. After comparison, it was determined that only the normal stress ratio criterion correctly predicts the direction of crack extension.
Static Compression Failure of Carbon Fibre T800/924C Composite Plate with a Single Hole
Authors: Soutis C. , Fleck N.A. 
Published: March 2007

This paper describes an experimental and theoretical study of the compres sive failure of carbon/epoxy, T800/924C, composite laminates. Static tests were carried out to investigate the mechanics of uniaxial compressive failure in multidirectional unnotched [(±45/02)3] s plates. Fibre microbuckling in the 0° plies is the critical damage mode which causes fracture of the composite plate. A series of experiments was also carried out to determine the failure in compressively loaded [(±45/0 2)3] s laminates with circular holes. X-ray radiography and scanning elec tron microscopy were used to observe damage initiation and propagation. Failure is initi ated as matrix cracking. With increasing load fibre microbuckling, surrounded by delami nation, occurs at the edges of the hole at locations of high in-plane compressive stress. When damage reached a critical state the laminate failed catastrophically. Finally, a theoretical model is presented for predicting the static strength of notched laminates. Theoretical predictions are compared with experimental data for specimens containing circular holes of different sizes. Agreement of theory with test data is ac ceptable.
Characterization of the Creep Compliances J22 and J66 of Orthotropic Composites with PEEK and Epoxy Matrices Using the Nonlinear Viscoelastic Response of the Neat Resins
Authors: Horoschenkoff A. 
Published: March 2007

The tensile creep behavior of two resins used as matrices in high- performance carbon-fiber-reinforced composites was characterized by using Schapery's nonlinear viscoelastic constitutive equation. The investigation was performed on Poly etheretherketone (PEEK) and a toughened epoxy resin. Two equations from the micromechanics of composites were modified by involving nonlinear viscoelastic matrix behavior. These modified equations were used to predict the nonlinear creep compliances J22 and J66 of carbon-fiber-reinforced composites having the investigated matrices. The prediction was verified by creep tests on laminates with fiber orientation [904]s and [±454]s. It was found that the modified equations allow good prediction of the creep compliances J22 and J66. The maximum difference between predicted and measured creep strain is less than 12%.
Micromechanics Prediction of the Shear Strength of Carbon Fiber/Epoxy Matrix Composites: The Influence of the Matrix and Interface Strengths
Authors: King T.R. , Blackketter D.M. , Walrath D.E. , Adams D.F. 
Published: March 2007

Presently there is great interest in understanding and improving the bond ing between the fibers and matrix in high performance composite materials. Indeed, the fiber-matrix adhesion in many recently-developed systems is poor. To improve bonding, various fiber surface treatments have been developed. These treatments are often evaluated by measuring their effect on a composite property sensitive to the interfacial bond strength (e.g., the composite shear strength). Such methods are, however, inferential, and do not provide a direct measure of the strength of the interfacial bond. A method is presented to estimate the influence of the matrix and the interfacial bond strength itself on the composite shear strength for a given fiber/matrix composite. Analyti cal prediction of these effects has been achieved using a finite element micromechanics model. Numerical results generated using this model have been shown to compare well with experimental data, which suggests that the micromechanics approach to predicting constituent and interface effects on the composite shear strength is a potentially valuable tool.
A Model of Embedded Fiber Optic Fabry-Perot Temperature and Strain Sensors
Authors: Kim Ki-Soo , Kollár László , Springer George S. 
Published: March 2007

A model was developed for embedded intrinsic and extrinsic Fabry-Perot fiber optic sensors. This model relates the strains and the temperature changes in the material surrounding the sensor to the reflected light intensity. The model consists of three parts. Submodel I relates the temperature and the strains in the material to the temperature and the strains inside the sensor. Submodel 2 relates the temperature and the strains inside the sensor to the change in sensor length and to the changes in the optical properties of the sensor. Submodel 3 relates the changes in sensor length and optical properties to the changes in the intensity of the reflected light. On the basis of the model, a computer code SENSOR1 was written which can be used to calculate the reflected light intensity for specified strains and temperature changes inside the material. The model and the code were verified by measuring changes in the light in tensity of an intrinsic Fabry-Perot sensor embedded in a graphite-epoxy composite plate subjected to loads varying with time. The changes in light intensities were measured and were also calculated by the code. The measured and calculated light intensities were found to be in good agreement.
Optimal Retaliation for Optimal Cooperation
Authors: Mueller Ulrich 
Published: March 2007

There has been a growing number of theoretical as well as experimental investigations on the emergence of evolutionarily stable cooperative strategies in the iterated Prisoner's Dilemma game. From a methodological viewpoint, investigations of this sort suffer so far from two shortcomings. The phenomenon of noise, that is, any deviation from the assumption of perfect information among the players, has been given only unsystematic consideration, if any. Furthermore, only insufficient notice has been taken of a recent major development within game theory, dynamical population games, which allow the analysis of games with an infinite number of players in a much more concise and compact way than before. The model presented in this article allows us to study the interactions among conditionally cooperative strategies—reactive strategies—in iterated Prisoner's Dilemma population games in noisy environments with this powerful new analytical tool. The main results are: Under noise, the best strategy to establish cooperation in a world of noncooperators is GRIM, the strategy that begins with a cooperative move, but never cooperates again, once a defection occurs; the best strategy to maintain already established cooperation, however, is a more or less restrained version of TIT-FOR-TAT (how much restrained depends on the necessary safety margin against an eventual reinvasion of noncooperators); cooperating with unconditional cooperators—ALL COOPERATE—destroys the social order.
The Phenomenology of Belief Systems
Authors: Hersh Tom 
Published: March 2007

In our journeys through life, sometimes we get lost. Suddenly people appear from all around offering us maps that will show us the right direction. Even when we're not lost and we're walking down the street toward some specific goal, fanatics try to drag us to their meetings where supposedly we will learn about the true path and the error of our ways. In this article I focus on the world views and advice given by religions, psychotherapies, cults, and schools. I call these groups that offer such advice, "systems." The reader is reminded of what it is like to be approached by a person representing a belief system, and also of the great variety of such systems that exist in our culture. Next, some characteristics of systems are presented. Then, the reader is asked to identify with an imaginary individual who has "fallen into" a system and to join him on a phenomenological journey through five stages or levels of his relationship to systems.
Replacement Policy
Authors: Neild R. R. 
Published: March 2007

This note presents the results of a questionnaire enquiry into replacement policies used in a sample of firms, mainly in the engineering industry.The enquiry was made as one part of a study of strategic factors in economic growth. This broader study has been focussed on the question : what factors influence the pace at which new and more efficient units of production, whether whole plants or individual machines, are introduced into industry in place of old ones, thus giving rise to increased productivity ?
L'appartenance religieuse et I'utilisation des loisirs du dimanche
Authors: Hessels A. 
Published: March 2007

The author examines the incidence of religious practice, and in particular attendance at services, on the use of time on Sundays in four cities in the Low Countries: Amsterdam, Rotterdam, Hilversum and Zaandam. Certain differences come out very clearly, especially among Calvinists. Among Catholics and Lutherans the use of time is more or less the same, especially during the Sunday afternoon. The author analyses in the light of these findings differences in religious practice between members of these churches in terms of age and socio-economic group.