bluuebunny/crossref_metadata_2025 huggingface dataset:
Programmable Force Fields for Distributed Manipulation, with Applications to MEMS Actuator Arrays and Vibratory Parts Feeders
Authors: Bohringer Karl-Friedrich , Donald Bruce Randall , MacDonald Noel C.
Published: December 2004

Programmable force vector fields can be used to control a variety of flexible planar parts feeders such as massively parallel microactuator arrays or transversely vibrating (macroscopic) plates. These new automation designs promise great flexibility, speed, and dexterity—we believe they may be employed to position, orient, singulate, sort, feed, and assemble parts. However, since they have only recently been invented, programming and controlling them for manipulation tasks is challenging. When a part is placed on our devices, the programmed vector field induces a force and moment upon it. Over time, the part may come to rest in a dynamic equilibrium state. By chaining sequences of force fields, the equilibrium states of a part in the field may be cascaded to obtain a desired final state. The resulting strategies require no sensing, and enjoy efficient planning algorithms.

This paper begins by describing new experimental devices that can implement programmable force fields. In particular, we describe our progress in building the M-CHIP (Manipulation CHIP), a massively parallel array of programmable micromotion pixels. Both the M-CHIP and other microarray devices, as well as macroscopic devices such as transversely vibrating plates, may be programmed with vector fields, and their behavior predicted and controlled using our equilibrium analysis. We demonstrate lower bounds (i.e., impossibility results) on what the devices cannot do, and results on a classification of control strategies yielding design criteria by which well-behaved manipulation strategies may be developed. We provide sufficient conditions for programmable fields to induce well-behaved equilibria on every part placed on our devices. We define composition operators to build complex strategies from simple ones, and show the resulting fields are also well behaved. We discuss whether fields outside this class can be useful and free of pathology.

Using these tools, we describe new manipulation algorithms. In particular, we improve existing planning algorithms by a quadratic factor, and the plan length by a linear factor. Using our new and improved strategies, we show how to simultaneously orient and pose any part, without sensing, from an arbitrary initial configuration. We relax earlier dynamic and mechanical assumptions to obtain more robust and flexible strategies.

Finally, we consider parts feeders that can only implement a very limited ”vocabulary” of vector fields (as opposed to the pixel-wise programmability assumed above). We show how to plan and execute parts posing and orienting strategies for these devices, but with a significant increase in planning complexity and some sacrifice in completeness guarantees. We discuss the trade-off between mechanical complexity and planning complexity.
Minimum-Effort Motions for Open-Chain Manipulators with Task-Dependent End-Effector Constraints
Authors: Martin Bryan J. , Bobrow James E.
Published: December 2004

In this article, we examine the solution of minimum-effort optimal control problems for open-chain manipulators. An approximate Solution to the optimal control problem is determined by a constrained parameter optimization over a set of B-spline basis functions. We demonstrate that the parameter-optimization formulation of the problem is numerically ill-conditioned, and that it is therefore essential to include analytic, or exact, gradients of the objective fiunction and the constraints in order to guarantee a solution. A recursive expression for these gradients is developed for general serial chains. Constraints on end-effector motions are taken into account using the logarithmn of the spatial displacement. Our formulation relies on the use of matrix exponentials for the manipulator kinematics, dynamics, and task constraints. Several examples are presented that demostrate the power and flexibility of our approach.
Kernel for Modular Robot Applications: Automatic Modeling Techniques
Authors: Chen I-Ming , Yeo Song Huat , Chen Guang , Yang Guilin
Published: December 2004

A modular robotic system consists of standardized joint and link units that can be assembled into various kinematic configurations for different types of tasks. For the control and simulation of such a system, manual derivation of the kinematic and dynamic models, as well as the error model for kinematic calibration, require tremendous effort, because the models constantly change as the robot geometry is altered after module reconfiguration. This paper presents a framework to facilitate the model-generation procedure for the control and simulation of the modular robot system. A graph technique, termed kinematic graphs and realized through assembly incidence matrices (AIM), is introduced to represent the module-assembly sequence and robot geometry. The kinematics and dynamics are formulated based on a local representation of the theory of Lie groups and Lie algebras. The automatic model-generation procedure starts with a given assembly graph of the modular robot. Kinematic, dynamic, and error models of the robot are then established, based on the local representations and iterative graph-traversing algorithms. This approach can be applied to a modular robot with both serial and branch-type geometries, and arbitrary degrees of freedom. Furthermore, the AIM of the robot naturally leads to solving the task-oriented optimal configuration problem in modular robots. There is no need to maintain a huge library of robot models, and the footprint of the overall software system can be reduced.
Metrics and Connections for Rigid-Body Kinematics
Authors: Žefran Miloš , Kumar Vijay , Croke Christopher
Published: December 2004

The set of rigid-body motions forms a Lie group called SE(3), the special Euclidean group in three dimensions. In this paper, we investigate possilble choices of Riemannian metrics and affine connections on SE(3) for applications to kinematic analysis and robot-trajectory planning. In the first part of the paper, we study metrics whose geodesics are screw motions. We prove that no Riemannian metrics call have such geodesics, and we show that the metrics whose geodesics are screw motions form a two-parameter family of semi-Riemannan metrics. In the second part of the paper, we investigate affine connections which through the covariant derivative give the correct expression for the acceleration of a rigid body. We prove that there is a unique symmetric connection with this property. Furthermore, we show that there is a family of Riemannian metrics that are compatible with such a connection. These metrics are products of the bi-invariant metric on the group of rotations and a positive-definite constant metric on the group of translations.
Conditions for Kinematic Stability of Position/Force Control for Robots
Authors: Doulgeri Z.
Published: December 2004

This corresponance aims at correcting and clarifying the stability conditions given in Doulgeri, Fahantidis and Paul (1998) for selected error schemes in hybrid position/ force control.

Sufficient kinematic stability conditions require not only symmetry of the equivalent Joint error projection matrix (Doulgeri, Fahantidis and Paul 1998) but also equal control gains. The positive definiteness of the system's potential function depends on the existence and magnitude of the contact stiffness. Full velocity feedback is required to ensure asymptotic stability.
A Path-Tracking Criterion for an LHD Articulated Vehicle
Authors: Altafini Claudio
Published: December 2004

A path-tracking criterion for the so-called LHD (load-haul-dump) truck used in underground mining is proposed in this paper. It exploits the particular configuration of this vehicle, composed of two units connected by an actuated articulation. The task is to follow the path represented by the middle of the tunnel, maintaining the whole vehicle at a reduced distance from the path itself, to decrease the risk of crashes against the walls of the tunnel. This is accomplished via feedback through the synthesis of an appropriate path-tracking criterion. The criterion is based on monitoring the distances of the midpoints of both axles of the vehicle from their orthogonal projections on the path, using two different moving frames simultaneously. Local asymptotic stability to paths of constant curvature is achieved by means of linear-state feedback.
A Comparative Study of Vision-Based Lateral Control Strategies for Autonomous Highway Driving
Authors: Taylor Camillo J. , Košecká Jana , Blasi Robert , Malik Jitendra
Published: December 2004

With the increasing speeds of modern microprocessors, it has become ever more common for computer-vision algorithms to find application in real-time control tasks. In this paper, we present an analysis of the problem of steering an autonomous vehicle along a highway based on the images obtained from a CCD camera mounted in the vehicle. We explore the effects of changing various important system parameters like the vehicle velocity, the look-ahead range of the vision sensor, and the processing delay associated with the perception and control systems.

We also present the results of a series of experiments that were designed to provide a systematic comparison of a number of control strategies. The control strategies that were explored include a lead-lag control law, a full-state linear controller, and an input-output linearizing control law. Each of these control strategies was implemented and tested at highway speeds on our experimental vehicle platform, a Honda Accord LX sedan.
Avoiding Moving Obstacles by Deviation from a Mobile Robot’s Nominal Path
Authors: Tsoularis A. , Kambhampati C.
Published: December 2004

This paper deals with the problem of obstacle avoidance by deviation from the nominal path. Deviation is the only option available to the robot when the acceleration or deceleration plan on the nominal path fails to produce a viable avoidance strategy. The obstacle avoidance on the nominal path was dealt with in our previous development, where the robot’s motion was only subject to an upper bound on its speed. When the robot has to deviate, its motion is subject to a maximum steering constraint and a maximum deviation constraint in addition to the maximum speed constraint. The problem is solved geometrically by identifying final states for the robot that are reachable, satisfy all the constraints, and guarantee collision avoidance. The final state-reachability conditions that we obtain in the process ensure that no unnecessary deviation plan is initiated. These conditions, along with the simplicity of the geometric arguments we employ, make our scheme an attractive option for on-line implementation. The only significant complexity arises when minimizing the performance index. We have suggested dynamic programming as an optimization tool, but any other nonlinear optimization technique can be adopted.
Pose and Motion from Contact
Authors: Jia Yan-Bin , Erdmann Michael
Published: December 2004

In the absence of vision, grasping an object often relies on tactile feedback from the fingertips. As the finger pushes the object, the fingertip can feel the contact point move. If the object is known in advance, from this motion the finger may infer the location of the contact point on the object, and thereby, the object pose. This paper primarily investigates the problem of determining the pose (orientation and position) and motion (velocity and angular velocity) of a planar object with known geometry from such contact motion generated by pushing.

A dynamic analysis of pushing yields a nonlinear system that relates through contact the object pose and motion to the finger motion. The contact motion on the fingertip thus encodes certain information about the object pose. Nonlinear observability theory is employed to show that such information is sufficient for the finger to “observe” not only the pose, but also the motion of the object. Therefore, a sensing strategy can be realized as an “observer” of the nonlinear dynamical system. Two observers are subsequently introduced. The first observer, based on the work of Gauthier, Hammouri, and Othman (1992), has its “gain” determined by the solution of a Lyapunov-like equation; it can be activated at any time instant during a push. The second observer, based on Newton’s method, solves for the initial (motionless) object pose from three intermediate contact points during a push.

Under the Coulomb-friction model, the paper deals with support friction in the plane and/or contact friction between the finger and the object. Extensive simulations have been done to demonstrate the feasibility of the two observers. Preliminary experiments (with an Adept robot) have also been conducted. A contact sensor has been implemented using strain gauges.
On the Hybrid Localization/Envelopment Problem
Authors: Chu Y. X. , Gou J. B. , Li Z. X.
Published: December 2004

The problem of aligning the CAD model of a workpiece such that all points measured on the finished surfaces of the workpiece match closely to corresponding surfaces on the model while all unmachined surfaces lie outside the model is referred to as the hybrid localization/envelopment problem. The hybrid problem has important applications in setting up for machining of partially finished workpieces. This paper gives a formulation of the hybrid localization/envelopment problem, and presents a simple algorithm for computing its solutions. First, we show that when the finished surfaces of a workpiece are inadequate to fully constrain the rigid motions of the workpiece, then the set of free motions remaining must form a subgroup G0 of the Euclidean group SE(3). This allows us to decompose the hybrid problem into a (symmetric) localization problem on the homogeneous space SE(3)/G0 and an envelopment problem on G0. While the symmetric localization problem is solved using the fast symmetric localization (FSL) algorithm developed in one of our earlier papers, the envelopment problem is solved by computing the solutions of a sequence of linear programming (LP) problems. We derive explicitly the LP problems, and apply standard linear programming techniques to solve the LP problems. We present simulation results to demonstrate the effectiveness of our method for the hybrid problem.
Communication on Optimal Grip Points for Contact Stability
Authors: Mantriota Giacomo
Published: December 2004

The identification of contact points is a priority in planning grasps. This paper proposes a criterion for the determination of optimal grip points to secure contact stability. The criterion is generally valid, that is, it applies to grasps with any number of contact points on objects having a generic shape (polygonal or curved), and does not require that the external force acting on the object be known. A grasp-quality index, fmin, obtained by minimizing the friction coefficient needed to ensure contact stability in the presence of a generic disturbing external action, has been introduced. The criterion leads to the formulation of an optimization problem with nonlinear constraints that is easy to implement. Finally, some examples are provided which compare the results reported in the literature with the results obtained by applying the criterion proposed in this paper.
The Annular Ligament
Authors: Bozkurt Murat , Acar Halil İbrahim , Apaydin Nihal , Leblebicioglu Gürsel , Elhan Alaittin , Tekdemir İbrahim , Tonuk Ergin
Published: December 2004

Background

Despite documentations of ligamentous structures of the elbow, the anatomy and clinical and functional importance of the annular ligament has not been comprehensively defined in the orthopaedic literature.

Hypothesis

The annular ligament is an important component of both the proximal radioulnar and humeroradial joints, as well as an important component of the neighboring muscles and ligaments.

Study Design

Descriptive laboratory study.

Materials and Methods

To investigate the annular ligament and its relationship with neighboring structures, macroscopic and microscopic dissections were performed on both upper extremities of 30 cadavers (12 female and 18 male) fixed in 10% formaldehyde and on 1 upper extremity of a fresh cadaver (male).

Results

The distal ulnar insertion of discrete fibers on the supinator crest was defined as the inferior oblique band of the annular ligament, and the proximal insertion of the annular ligament was defined as the superior oblique band of the annular ligament. These patterns were noted in all specimens. It was difficult to distinguish the fibers of the supinator muscle in every specimen because they were intimately fused with the fibers of the annular ligament.

Conclusions

The superior and inferior oblique bands of the annular ligament attached proximally and distally onto the ulna, thus helping to secure the annular ligament in place.
Upper and Lower Extremity Muscle Fatigue after a Baseball Pitching Performance
Authors: Mullaney Michael J. , McHugh Malachy P. , Donofrio Tom M. , Nicholas Stephen J.
Published: December 2004

Background

Previous studies have estimated joint torques and electromyogram activity associated with the pitching motion. Although previous studies have investigated the influence of extended pitching (fatigue) on kinematic and kinetic parameters, no attempts have been made to quantify the fatigue associated with a pitching performance.

Purpose

Considering previous investigations on muscle activity during pitching, this study investigated muscle fatigue in upper and lower extremity muscle groups after a pitching performance.

Study Design

Descriptive laboratory study.

Methods

Thirteen baseball pitchers from 4 universities and 1 independent minor league team were tested before and after 19 games. Pitchers threw an average of 99 pitches during an average of 7 innings. Shoulder, scapular, and lower extremity muscle strengths were assessed using a handheld dynamometer before and after the pitching performances.

Results

Baseline strength tests revealed that the pitching arm was 12% weaker (P =. 02) in the empty can test (supraspinatus) compared to the contralateral side. Postgame shoulder strength tests revealed selective fatigue of 15% in shoulder flexion (P =. 02), 18% fatigue in internal rotation (P =. 03), and 11% fatigue in shoulder adduction (P =. 01). Minimal fatigue was noted in the empty can test, scapular stabilizers, and hip musculature.

Conclusions

A trend toward significant baseline strength in internal rotation together with significant selective postgame fatigue on internal rotation of the dominant upper extremity indicate that the internal rotators experience a high performance demand during pitching. Weakness in the empty can test on the dominant arm combined with minimal postgame fatigue was surprising given that studies and injury patterns have indicated a high performance demand on the supraspinatus during pitching.
Collagen/Chitosan/Heparin Complex with Improved Biocompatibility for Hepatic Tissue Engineering
Authors: Yu Xing , Bichtelen Alexandra , Wang Xiaohong , Yan Yongnian , Lin Feng , Xiong Zhuo , Wu Rendong , Zhang Renji , Lu Qingping
Published: December 2004

To make an implantable bioartificial liver (IBL), a new biocompatible collagen/chitosan/heparin complex was prepared using a crosslinking agent. The X-ray photoelectron spectroscopy (XPS), mechanical strength and biocompatibility with whole blood and hepatocytes were measured. The collagen/chitosan/heparin complex resulted in a superior blood compatibility compared to 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) crosslinked collagen matrix. The morphology and behavior of the cells on the collagen/chitosan/heparin membrane were found to be different from those on the collagen and collagen/chitosan membranes. Cells on the collagen membrane formed smaller three-dimensional aggregates than those on the collagen/chitosan membrane, while on the collagen/chitosan/heparin membrane, a round shape with no junctions were manifested. No adverse effects were found on the viability and function of the hepatocytes on the collagen/chitosan/heparin membrane compared to the collagen and collagen/chitosan membranes. These results suggest that this collagen/chitosan/heparin matrix is a potential candidate for hepatic tissue engineering.
Matrix Resin Effects on Selected Physicochemical Properties of Amorphous Calcium Phosphate Composites
Authors: Antonucci J. M. , Skrtic D.
Published: December 2004

Amorphous calcium phosphate (ACP)-filled bioactive composites show promise in a number of dental applications. This study focused on polymer-filler bonding as a way to improve physicochemical properties of these composites. Photoactivated resins were formulated from ethoxylated bisphenol A dimethacrylate (EBPADMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA) and methacryloxyethyl phthalate (MEP) with four different EBPADMA/TEGDMA mass ratios (1.0, 0.67, 0.5 and 0.25) and a constant HEMA/MEP mass ratio of 2.0. Composites were prepared with the zirconia-ACP (mass fraction 40%). Composites and copolymers were evaluated for their biaxial flexure strength (BFS), degree of vinyl conversion (DC) and water sorption (WS). Composites were also assessed for mineral ion release and polymerization shrinkage (PS). Independent of resin composition, the average BFS was 130±24MPa for both the dry and aqueous-immersed copolymers, but was 70±11MPa for the dry composites and 47±7MPa for the wet composites. The average DC of all of the composites was 84±5% and showed little dependence on resin composition. The WS of both copolymers and composites was 3.2±0.6% with resin composition being a factor in only one formulation EBPADMA/TEGDMA 0.67. Overall ion release was significantly above the theoretical minimum necessary for remineralization. However, Ca ion levels were lower than that observed previously for similar composites based on resins without MEP. This is most likely due to their binding with the carboxylic acid groups of MEP. Since the DC of the copolymers and the PS of the composites both increased with decreasing EBPADMA/TEGDMA ratio in the resin, elevating the EBPADMA/TEGDMA ratio in the resin seems to be an obvious way to improve the PS of composites without adversely affecting the BFS, WS and/or ion release, while only marginally reducing the DC.
Bandwidth Characterization in the Micropositioning of Ionic Polymer Actuators
Authors: Kothera Curt S. , Leo Donald J.
Published: December 2004

Ionic polymers are electromechanically coupled smart materials that can be used as both actuators and sensors. As flexible actuators, these materials have been known to exhibit nonlinear behavior, but the present work shows that linear control techniques can greatly improve the open-loop response. However, because material dehydration results in changing system parameters, the linear control designs only offer a stable system for a limited amount of time (approximately 30 s). This study shows that the application of integral control to ionic polymer actuators can provide precise tracking performance to a reference step input. The actuator’s response to frequencies is also studied, in both the time and frequency domain. The frequency response analysis offers insight into the bandwidth of the actuators, where it was shown that the closed-loop bandwidth of the cantilever actuator is approximately 10% of its first resonance frequency. Simulations are performed with a linear empirical model of a cantilevered actuator, while both clamped-free and clamped-clamped configurations are tested in control experiments.
Magnetic Rubber Having Magnetic Clusters Composed of Metal Particles
Authors: Shimada Kunio , Shuchi Shigemitsu , Kanno Hideto
Published: December 2004

For the purpose of assembling metal particles on a nano- or microscale, in a previous investigation the authors had succeeded in extracting magnetic clusters from an intelligent fluid responsive to a magnetic field. The clusters are shaped like rods or needles and range from macroscopic to microscopic in size. In the present paper, a method for producing silicon rubber that contains the magnetic clusters is presented and its magnetic, mechanical, and physical properties are discussed. This new material shows superpara and anisotropic magnetization. In addition, the tensile strain of the material in relation to normal stress changes due to the existence of the magnetic clusters is studied. This material can be used in engineering applications.
Do Raters Consider the Influence of Situational Factors on Observed Performance When Evaluating Performance? Evidence From Three Experiments
Authors: Jawahar I. M.
Published: December 2004

Theory and research suggest that both person and situation influence observed performance. System or situational factors can either enhance or constrain performance. If raters do not compensate for the influence of situational factors, ratings will be contaminated with situational influences and will fail to validly reflect the true level of performance. Whether or not raters incorporate the influence of the conditions under which performance is achieved when evaluating employee performance is a fundamental issue with broad implications. Three experiments were conducted to directly examine if raters adjust their ratings to account for the influence of situational conditions. Results of Experiments 1 and 2 demonstrate that raters, in fact, adjust ratings to incorporate situational influences, and results of Experiment 3 indicate that raters who are high self-monitors are better than low self-monitors in terms of incorporating situational influences into ratings. Implications of results for the broader performance-appraisal literature are discussed, and suggestions are offered to practitioners.
Suicidal Ideation Among 8-Year-Olds Who Are Maltreated and At Risk: Findings From the LONGSCAN Studies
Authors: Thompson Richard , Briggs Ernestine , English Diana J. , Dubowitz Howard , Lee Li-Ching , Brody Kate , Everson Mark D. , Hunter Wanda M.
Published: December 2004

Suicidal ideation was examined among 1,051 8-year-old children identified as maltreated or at risk for maltreatment. Of these children, 9.9% reported suicidal ideation. Many variables, including maltreatment, had bivariate associations with suicidal ideation. Severity of physical abuse, chronicity of maltreatment, and the presence of multiple types of maltreatment strongly predicted suicidal ideation. In multivariate analyses of the domains of proximity, only ethnic background remained significant among demographic variables, only witnessed violence and maltreatment remained significant among family or contextual variables, and only child psychological distress, substance use, and poor social problem solving remained significant among child variables. The effects of ethnicity, maltreatment, and witnessed violence on suicidal ideation were mediated by child functioning. There were few interactions between maltreatment and other factors to predict suicidal ideation. Children who are maltreated and those exposed to community and domestic violence are at increased risk of suicidal ideation, even by age 8.
Child Maltreatment in Depressed Adolescents: Differences in Symptomatology Based on History of Abuse
Authors: Danielson Carla Kmett , de Arellano Michael A. , Kilpatrick Dean G. , Saunders Benjamin E. , Resnick Heidi S.
Published: December 2004

Research has demonstrated that youth who are sexually or physically abused are at greater risk for developing depression. Although the association between depression and child maltreatment has been well documented, much less is known about the potential differences in the clinical presentation of depressive symptomatology among these victims. The current study examines differences in symptoms of depression in adolescents based on differing histories of abuse (i.e., sexual abuse only, physical abuse only, sexual and physical abuse, and no history of sexual or physical abuse), abuse incident characteristics, and gender. Participants were drawn from a subsample (n = 548) from the National Survey of Adolescents who met criteria for major depressive episode in the past year. Results indicate significant differences in severity of depression and specific depressive symptoms based on type of abuse experienced and gender. Implications for the clinical assessment and treatment of depressed adolescents with regard to abuse history are discussed.
The Internet and Family and Acquaintance Sexual Abuse
Authors: Mitchell Kimberly J. , Finkelhor David , Wolak Janis
Published: December 2004

This article explores the dynamics of cases involving family and acquaintance sexual offenders who used the Internet to commit sex crimes against minors. Although the stereotype of Internet crimes involves unknown adults meeting juvenile victims online, Internet use can also play a role in sexual crimes against minors by family members and acquaintances. Data were collected from a national sample of law enforcement agencies about arrests for Internet-related sex crimes against minors. Family and acquaintance offenders were nearly as numerous as offenders who used the Internet to meet victims online. They used the Internet in various ways to further their crimes including as a tool to seduce or groom, store or disseminate sexual images of victims, arrange meetings and communicate, reward victims, or advertise or sell victims. Prevention messages and investigation approaches should be revised to incorporate awareness of such cases and their dynamics.
The Poetry in Portraiture: Seeing Subjects, Hearing Voices, and Feeling Contexts
Authors: Hill Djanna A.
Published: December 2004

Creating poetic portraits allows scholars to communicate research findings in multidimensional and more accessible ways. The author explores womanist theory and two dimensions of portraiture research—context and voice—used to create poetic portraits about the experiences and practices of three Black women teacher educators. Research participants included Olivia, an assistant professor at a predominately White, comprehensive higher education institution; Tulip, an associate professor at a liberal arts and predominately Black higher education institution; and Tulani, an associate professor at a predominately Black research institution. Data were collected through interview, observation and shadowing, and document review to answer two research questions: In what ways do the participants’ experiences as outsiders-within inform their practices? and How does the theme of race uplift inform the participants’ pedagogy? Examples are presented of poetic techniques from research. The author discusses the use of poetry as a means for educational scholarship to influence wider audiences.
Sylvia Plath’s Man in Black
Authors: Hunter Dianne
Published: December 2004

The male muse in the psychic territory Adrienne Rich called in 1971 ‘The Man’ represents sexualized death and phallic mourning, a concept of masculinity marked by the legacy of the 20th century’s two world wars. In the context of representations of ‘The Man’ in North American white women writers coming of age in the late 1950s and early 1960s (Adrienne Rich, Joyce Carol Oates, Margaret Atwood), Sylvia Plath’s journal account of the Saint Botolph’s Review party, where she met her husband, and its fictional transformation in her 1957 short story, ‘Stone Boy with Dolphin’, demonstrate Plath’s examination of the Bostonian Puritan heritage and the psychic aftermath of the Second World War. Plath’s constructions of heterosexual romance as participating in the history of Fascism and her concept of writing as sexy violence coincide culturally with Lacan’s theory of phallic signification.
Perceptions of the Intergroup Structure and Anti-Asian Prejudice Among White Australians
Authors: Johnson Daniel , Terry Deborah J. , Louis Winnifred R.
Published: December 2004

Subjective intergroup beliefs and authoritarianism were assessed in a field study ( N = 255) of White Australians’ anti-Asian stereotyping and prejudice. A social identity analysis of intergroup prejudice was adopted, such that perceptions of the intergroup structure (instability, permeability, legitimacy and higher ingroup status) were proposed as predictors of higher prejudice (blatant and covert) and less favorable stereotyping. Consistent with the social identity approach, both independent and interacting roles for sociostructural predictors of Anti-Asian bias were observed, even after demographic and personality variables were controlled. For example, perceived legitimacy was associated with higher prejudice when White Australians’ status position relative to Asian Australians was valued. Moreover, when participants evaluated Whites’ position as unstable and high status or legitimate, perceptions of permeable intergroup boundaries were associated with anti-Asian bias. The present findings demonstrate status protection responses in advantaged group members in a field setting, lending weight to the contention that perceptions of sociostructural threat interact to predict outgroup derogation. Implications for theories of intergroup relations are discussed.
The Effect of Group Decision Making on Cooperation in Social Dilemmas
Authors: Hopthrow Timothy , Hulbert Lorne G.
Published: December 2004

A robust finding in social dilemma research is an increase in individual cooperative choice following group discussion about the dilemma. To elaborate the idea that this effect arises from the development of within-group consensus, groups of six made explicit group decisions about their subsequent individual choice. Perceived demonstrability of cooperativeness in the dilemma was manipulated through changes both to instructions and the incentives of the dilemma. As demonstrability decreased, so did the proportion of groups deciding to cooperate, leading to a reduction in the group discussion effect. Social decision scheme analysis supported the demonstrability-group decision hypothesis. The interaction between demonstrability, individual opinions and group process is proposed to explain the group discussion effect.
Copper(II) Triflate Immobilized in [bmim]BF4 Ionic liquid: An Efficient Reaction Medium for Michael Addition of β-Ketoesters to Acceptor-activated Alkenes
Authors: Yadav J S , Reddy B V S , Baishya Gakul , Narsaiah A Venkat
Published: December 2004

1,3-Dicarbonyl compounds undergo smooth conjugate addition to α,β-unsaturated ketones in the presence of 10 mol % copper(II) triflate immobilized in air and moisture stable [bmim]BF4 ionic liquid under extremely mild conditions to afford the corresponding Michael adducts in high to quantitative yield.
Highly Dispersed Gold Nanowires within the Pore Channels of Mesoporous Silica Thin Films Prepared From Organic–Inorganic Hybrid Films Functionalized with Basic Moieties
Authors: Gu Jinlou , Shi Jianlin , Hua Zile , Xiong Liangming , Zhang Lingxia , Li Lei
Published: December 2004

Combined a surface modification scheme with a neutralization reaction, accompanied with reduction procedure, highly dispersed gold nanowires within the pore channels of mesoporous silica thin films were prepared from organic–inorganic hybrid films modified with basic moieties.
Laboratory Investigation of Local Bending in Profiled Thermoplastic Pipes
Authors: Dhar Ashutosh S. , Moore Ian D.
Published: December 2004

Full-scale pipe tests were conducted to investigate local bending on profiles of different thermoplastic pipes. Five profiled pipes including two lined corrugated, one box and one tubular profile of HDPE material and one ribbed profile of PVC material were considered. The study demonstrates that a three-dimensional bending mechanism governs the strains on some components of the pipe profiles. The local bending was particularly significant in the lined corrugated and the tubular profiled pipes. The mechanism of the local bending at the crown and the springline was different for lined corrugated pipes under biaxial loading. Ratios of the circumferential strains on the liner to those at the inner wall were higher at the crown/invert than the ratios at the springline. The liner with longer span was found to undergo even lesser strain relative to the liner with shorter span. The local bending did not affect the strain on the other elements of the lined corrugated profile.
Diagonal Cracking and Ultimate Shear Strength of Slender High Strength Concrete Deep Beams
Authors: Chemrouk M. , Kong F. K.
Published: December 2004

To provide more information on the diagonal cracking in slender concrete deep beams and their design implications, loading tests were carried out on fifteen (15) slender concrete deep beams having height/thickness ratio in the range of twenty (20) to fifty (50). Due to the slenderness of the specimens, high strength concrete was used together with different arrangements and quantities of web reinforcement. Observations and measurements were made on the nature of cracking in general and on the diagonal cracks in particular and comparisons were made with those of stocky deep beams as reported in the literature. The effectiveness of web reinforcement in controlling diagonal cracks and enhancing the ultimate stength is discussed. The failure modes were described and both the diagonal cracking load and the failure load were recorded for comparison with those predicted by the CIRIA guide and by the ACI building code.

Using the test results and the observations made during the testing, a modification of the CIRIA shear equation is proposed so that it can be used to predict safely the diagonal cracking loads and the shear strengths of slender concrete deep beams. With this modification, the safety factor (Vmeasured/Vpredicted) approches the value of 2.0 which is what one would expect against a shear failure, particularly that high strength concrete tends to be a fairly brittle material. The CIRIA equation in its original form gives a safety factor just above 1.0, thus unsufficient against such failure. Indeed, the test results show that it may even be unsafe for the design of slender high strength concrete deep beams against shear.
High Strength Concrete Continuous Deep Beams — With Web Reinforcement and Shear-Span Variations
Authors: Chemrouk M. , Kong F. K.
Published: December 2004

Tests under two-point loads were carried out to destruction on 12 reinforced concrete two-span continuous deep beams. The beams were tested for two shear-span/depth ratios of 0.45 and 0.24 giving clear shear-span/depth ratio of 0.21 and 0.00 respectively. Various arrangements of web reinforcement were used such as minimum and maximum vertical bars, minimum and maximum horizontal bars and minimum and maximum inclined bars. Sagging and hogging tensile steel was used in accordance with the shallow beam bending moment distribution and was kept constant for all the beams. The results of the present tests are compared with those of the moderately deep beams reported in the litterature by Rogowsky et al. and with the two-beam tests of Leonhardth and Walther.

The present tests show that the current codes and design manuals covering continuous deep beams could lead to severe cracking and may be unsafe for this type of structural members. The actual bending moment distribution is completely different from that recommended by these documents, with moments at spans higher and those at internal supports lower. The tests also showed that the CIRIA guide may be too tolerant and hence unsafe towards bearing failure which, in the presence of an effective pattern of web reinforcement, is the dominant type of failure of reinforced concrete continuous deep beams.
Finite Element Analysis and Tests on Bolted End-Plate Connections in Steel Portal Frames
Authors: Shi Gang , Shi Yongjiu , Wang Yuanqing , Li Shaofu , Chen Hong
Published: December 2004

Bolted end-plate connections are being widely used in steel portal frames. In this paper, some tests on beam-to-column and beam-to-beam end-plate connections are reported and the corresponding finite element analysis (FEA) is carried out to analyze their loading resistance and rotational stiffness characteristics. The design method about extended end-plate connections in current design code is discussed, and the necessary improvements are proposed. Especially, some precautions about the classification criterion of the joint stiffness in steel structures are recommended. From the results of comparison, one new model of the bolt tension force distribution and the corresponding design method are presented. It has been verified by the tests that this method can calculate the actual stresses of the bolts and the end-plates more accurately and mobilize their loading capacities more efficiently with sufficient safety and reliability.
Coupled Analysis of Slip and Deflection for Continuous Composite Beams of Steel and Concrete
Authors: Zhou Lingyu , Yu Zhiwu , Jiang Lizhong
Published: December 2004

Experimental results for eleven continuous composite beams of steel and concrete are presented in this paper, which includes laws of deflection and slip between the concrete and steel. Governing differential equations of slip and deflection for simply supported composite beams with different boundary conditions and different loads are established, and a set of numerical expressions for slip and deflection of continuous composite beams are established by the superposition method as well. The deflection and slip of seventeen continuous composite beams are calculated by the numerical expressions. The calculated results show good agreement with the experimental results. The numerical results show that the slip of continuous composite beams increases and approaches the slip of sandwich panels without shear connectors. At the same time, the degree of shear connection influences deflection to a certain extent. The degree of shear connection influences deflections little at full shear connection and the increment of deflection caused by slip is less than 5% when the degree of shear connection is between 60 to 100%. When the degree of shear connection is between 80 to 140%, the strain in the lower flange of the steel beam at the internal-support is influenced little.
Free-Torsional Stiffness of Locally Buckled Thin-Walled Cross-Sections with Open Profiles
Authors: Tong Gengshu
Published: December 2004

The paper utilizes the approximate equivalence between local buckling and overall torsional buckling of cruciform cross section members with double axis symmetry under axial load to study the variation of the free torsional stiffness of thin-walled sections with open-profiles after buckling locally. It is found that the free-torsional stiffness is basically unchanged after the cross-section has buckled. This conclusion has significant meaning for the study of the interaction between local buckling and overall lateral-torsional buckling of thin-walled members with open profiles.
Enhanced Approach to Consistency in Gradient-Dependent Plasticity
Authors: Chen G. , Baker G.
Published: December 2004

This note proposes a modification of gradient-dependent plasticity to improve convergence. In gradient-dependent plasticity, the consistency condition, which results in a differential equation with respect to the plastic multiplier, is solved simultaneously with the equilibrium equation. In each iteration, the consistency condition is not really satisfied and the stress is generally not on the yield surface; this results in poor convergence. A modification is proposed, in which gradient-dependent plasticity is recast into the classical plasticity framework and a strict stress mapping strategy is established. Instead of solving a differential equation simultaneously with the equilibrium equation, the plastic multiplier is solved by minimizing a functional separately. The consistency condition can be satisfied and the stress is mapped back to the yield surface.
Rapid Method for β2-Transferrin in Cerebrospinal Fluid Leakage Using an Automated Immunofixation Electrophoresis System
Authors: Papadea Christine , Schlosser Rodney J
Published: December 2004

Background: β2-Transferrin (β-2 trf) is a desialated isoform of transferrin found only in cerebrospinal fluid (CSF), ocular fluids, and perilymph. In aural, nasal, and wound drainages, this protein is an important marker of CSF leakage. Immunofixation electrophoresis (IFE) on agarose gels is a widely accepted qualitative technique for detection of small amounts of β-2 trf, but disadvantages include lengthy transfer immunoblotting techniques or the requirement of at least 2 mL of sample.

Methods: Using eight applications of unconcentrated sample on high-resolution agarose gels with an automated electrophoresis system (Helena SPIFE 3000), we developed a rapid method for β-2 trf. Evaluation studies included reproducibility of migration distance (mm), limit of detection, specificity, and concordance of results compared with those reported by a reference laboratory. Neuraminidase-treated serum was the source of β-2 trf for our sensitivity and specificity studies. Transferrin was measured by rate nephelometry.

Results: The 2.5-h procedure demonstrated reproducible migration (CV <2.5%) on five lots of gels. Detection of β-2 trf at 0.002 g/L in an unconcentrated sample was attributed to reproducible application, quality of the anti-trf antiserum, and a sensitive acid violet stain. Our β-2 trf findings (two negative and five positive) in seven available clinical samples agreed with the reference laboratory results. In 12 months after its inception, this test was ordered 48 times vs 13 in the previous year when testing was sent out.

Conclusion: This method provides physicians with a rapid, reliable aid in the diagnosis of suspected CSF leakage, as described in a case report.
Accurate and Robust Quantification of Circulating Fetal and Total DNA in Maternal Plasma from 5 to 41 Weeks of Gestation
Authors: Birch Lyndsey , English Claire A , O’Donoghue Keelin , Barigye Olivia , Fisk Nicholas M , Keer Jacquie T
Published: December 2004

Background: Detection of fetal DNA in maternal plasma is achievable at 5 weeks of gestation, but few large-scale studies have reported circulating fetal and maternal DNA across all trimesters.

Methods: Blood samples were collected from 201 women between 5 and 41 weeks of pregnancy. Quantitative PCR was used to assess total and fetal DNA concentrations, and allelic discrimination analysis was investigated as a route to detecting specifically fetal DNA.

Results: Male fetuses were detectable from 5 weeks amenorrhea with increasing fetal DNA concentrations across gestation. The sensitivity of fetal male gender determination in pregnancies with live birth confirmation was 99%, with 100% specificity. Total DNA concentrations did not correlate with gestational age, but appeared slightly higher in the first and third trimesters than in mid-pregnancy. Analysis of short tandem repeats demonstrated that significant improvements in the detection limit are required for specific detection of fetal DNA.

Conclusions: The high sensitivity of PCR-based detection, together with quantification provided by real-time DNA analysis, has clear potential for clinical application in noninvasive prenatal diagnosis. However, accurate quantification using best-fit data analysis, standardization of methods, and performance control indicators are necessary for robust routine noninvasive diagnostics.