bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Divide-and-Conquer Articulated-Body Algorithm for Parallel O(log(n)) Calculation of Rigid-Body Dynamics. Part 2: Trees, Loops, and Accuracy
Authors: Featherstone Roy 
Published: July 2003

This paper is the second in a two part series describing a recursive, divide and conquer algorithm for calculating the forward dynamics of a robot mechanism, or a general rigid body system, on a parallel computer. This paper presents the general version of the algorithm. The derivation begins with an algorithm for kinematic trees, which is then extended to closed loop systems. The general algorithm achieves O(log(n)) time complexity on O(n) processors for all kinematic trees and a large subset of closed loop systems. This paper also presents a more accurate version of the algorithm and the results of some numerical accuracy tests that compare both versions with the standard articulated body algorithm. The tests use rigid body systems containing up to 1024 bodies, and they show that the divide and conquer algorithm is substantially less accurate than the best serial algorithm but still accurate enough to be useful.
Determination of 6D Workspaces of Gough-Type Parallel Manipulator and Comparison between Different Geometries
Authors: Merlet J -P. 
Published: July 2003

We consider in this paper a Gough-type parallel robot whose leg length values are constrained to lie within some fixed ranges and for which there may be mechanical limits for the motion of the passive joints. The purpose of this paper is to present algorithms to determine: • the constant orientation workspace: all the possible locations of the center of the platform that can be reached with a fixed orientation • thetotal orientation workspace: all the possible locations of the center of the platform that can be reached with any orientation in a set defined by three ranges for the orientation angles (the dextrous workspace is an example of total orientation workspace case, the three ranges being T [0,360] degree1) • the inclusive orientationworkspace: all the possible locations of the center of the platform that can be reached with at least one orientation among a set defined by three ranges for the orientation angles (the maximal or reachableworkspace is an example of inclusive orientation workspace, the three ranges being [0,360]) Most of these algorithms are based on a basic method: approximation of the result by a set of 3D or 6D boxes obtained from an initial estimation through a bisection process. The boxes in the result will either fully or partially lie inside the workspace: the bisection stops as soon as all the boxes that do not lie fully inside the workspace have a size that is lower than a fixed threshold. A companion algorithm enables to verification that any 6D workspace (i.e., a continuous set of poses) lies within the reachable workspace of the robot. The paper includes a comparison between the workspace volumes of four different robot geometries, which shows that for robots of similar dimensions the joints layout has a large influence on the workspace volume.
Estimating First-Order Geometric Parameters and Monitoring Contact Transitions during Force-Controlled Compliant Motion
Authors: de Schutter Joris , Bruyninckx Herman , Dutré Stefan , de Geeter Jan , Katupitiya Jayantha , Demey Sabine , Lefebvre Tine 
Published: July 2003

This paper uses (linearized) Kalman filters to estimate first-order geometric parameters (i.e., orientation of contact normals and location of contact points) that occur in force-controlled compliant motions. The time variance of these parameters is also estimated. In addition, transitions between contact situations can be monitored. The contact between the manipulated object and its environment is general, i.e., multiple contacts can occur at the same time, and both the topology and the geometry of each single contact are arbitrary. The two major theoretical contributions are 1) the integration of the general contact model, developed previously by the authors, into a state-space form suitable for recursive processing; and 2) the use of the reciprocity constraint between ideal contact forces and motion freedoms as the “measurement equation” of the Kalman filter. The theory is illustrated by full 3-D experiments. The approach of this paper allows a breakthrough in the state of the art dominated by the classical, orthogonal contact models of Mason that can only cope with a limited (albeit important) subset of all possible contact situations.
Non-Isothermal Modeling of Co-Rotating and Contra-Rotating Twin Screw Extruders
Authors: Avalosse Th. , Rubin Y. , Fondin L. 
Published: July 2003

The quality of the mixing of different raw materials, i.e. the uniformity of the mixture, is a key issue that will determine the morphology and the specific product properties of the resulting compound [1,2]. Numerical simulation of flow in extruder components provides a new insight, both qualitative and quantitative, into those features. 3-D transient numerical simulations of twin screw extruder (TSE) configurations are presented. A special method, the mesh superposition technique (MST), has been introduced to provide a convenient way to model intermeshing TSEs without involving any remeshing complexity [3]. It has been validated in previous work for isothermal cases [4]. To account for the important non-isothermal effects, the method is compared against numerical and experimental results for additional, non-isothermal validation [5]. We present an analysis of different non-isothermal features that characterize the flow induced by a co-rotating as well as a contra-rotating configuration. Both cases are compared in terms of pressure profiles, temperature fields, resulting torque imposed on the screws and from a mixing point of view to illustrate a typical analysis of different TSEs and provide objective information to select the most appropriate configuration for specific process requirements.
Optimization of Cooling Systems in Injection Molds by an Easily Applicable Analytical Model
Authors: Rao Natti S. , Schumacher Guenter , Schott Nick R. , O’brien Keith T. 
Published: July 2003

The production rate of injection-molded articles is determined by the cooling time of the polymer melt in the mold. By using state-of-the-art numerical software the mold design can be optimized in order to achieve fast cooling. However, the efforts required to apply this software do not always justify its use in dealing with the daily design problems. Taking the changing mold wall temperature into account a straightforward analytical procedure for optimizing the cooling channel lay-out for a thermoplastic resin has been developed. The equations in the model can be easily solved by means of a hand-held calculator, thus enabling quick estimates of the effect of relevant parameters on mold design. Results of numerous simulations and a worked-out example illustrate the application of the model which has led to good results in practice.
Solid Particle Erosion of Unidirectional GF Reinforced EP Composites with Different Fiber/Matrix Adhesion
Authors: Barkoula N. -M. , Karger-Kocsis J. 
Published: July 2003

The influence of interfacial modification and relative fiber orientation (parallel, Pa and perpendicular, Pe) on the solid particle erosion was investigated in unidirectional (UD) reinforced glass fiber (GF) epoxy (EP) composites. The interfacial modification was varied by GF sizing. The erosive wear behavior was studied in a modified sandblasting apparatus at three impact angles (30, 60 and 90). The surface topography of the eroded composites was investigated by a scanning electron microscope (SEM) and a non-contact 3D laser profilometer. The results showed a strong dependence of the erosive wear on the jet angle. The GF/EP systems presented a brittle erosion behavior, with maximum weight loss at 90 impact angle. It was established that good fiber/matrix adhesion improved the resistance to erosive wear. On the other hand, the relative fiber orientation had anegligible effect except the erosion at 30 impact angle. High roughness of the eroded surfaces indicated for high erosion rates, i.e. low resistance to solid particle erosion.
Hemocompatibility of Medical Connectors with Biopassive or Bioactive Surface Coatings
Authors: Wendel Hans P. , Hauser Nils , Briquet François , Ziemer Gerhard 
Published: July 2003

Although medical connectors compose very small parts of the extracorporeal circulation (ECC) systemthey represent a critical localization where early thromboembolic processes can manifest. In the present study we modified an in vitro closed-loop model with fresh human whole blood for the preclinical evaluation of the hemocompatibility of three types of medical connectors: non-coated (control); with silicone-, and heparin-coating. Each single loop consists of five polycarbonate connectors joined together by five pieces of silicone tubes. Thrombin-antithrombin-III, β-thromboglobulin (β-TG), PMN-Elastase, terminal complement complex, CD 11b expression, and surface-absorbed fibrinogen were measured. After 1 and 2 h recirculation, platelet loss, release of β-TG, and adsorption of fibrinogen were significantly higher ( p<0.05) within the non-coated connectors compared to the silicone- and heparin-coated groups. Following this experiment, the connectors were filled again with fresh heparinized whole blood from the same donor to evaluate the influence of prior blood contact. Here, the activation of platelets and coagulation was dependent on the duration of the blood preincubation period. Probably, the coated surfaces possess a reduced, or selective adsorption of plasma proteins, which in turn leads to a faster creation of a blood-friendly secondary superficial membrane, and prevents a further denaturation and hence activation of the adsorbed proteins.
Endothelial Cell Seeding of a 4-mm I.D. Polyurethane Vascular Graft
Authors: Fields Charles , Cassano Anthony , Allen Cynthia , Meyer Andrew , Pawlowski Kristin J. , Bowlin Gary L. , Rittgers Stanley E. , Szycher Michael 
Published: July 2003

We evaluated the extent (luminal coverage) of the endothelial cell (EC) lining/neointimal development and the thromboresistance of electrostatically EC seeded small diameter Chrono Flex-polyurethane vascular grafts. The evaluation consisted of harvesting autologous, canine jugular vein ECs, electrostatically seeding the polyurethane grafts (4-mm I.D., length = 6 cm) with the harvested ECs, implanting the grafts in a canine femoral artery model for four to six weeks, and excising the grafts for histological and scanning electron microscopy evaluations. Results of the histological evaluation (mid-graft region only) indicated that electrostatic EC seeding led to neointimal development and to minimal to no thrombus formation within the EC seeded grafts. The unseeded control grafts resulted in no neointimal development and substantial thrombus formation on the graft luminal surfaces. Scanning electron microscopy examination demonstrated a mature, confluent endothelium with a ‘‘cobblestone’’ appearance on the EC seeded graft luminal surface after six weeks. We conclude that electrostatic EC seeding enhanced the development of a neointima and reduced the incidence of thrombosis in polyurethane grafts implanted in a canine femoral artery model.
Analysis of Process-Induced Residual Stresses in Tape Placement
Authors: Sonmez Fazil O. , Hahn H. Thomas , Akbulut Mustafa 
Published: July 2003

The tape placement for thermoplastic composites involves heating, melting, and cooling steps just as do the other manufacturing processes. Consequently, development of residual stresses is unavoidable due to disparate thermal characteristics of matrix and fiber materials and also due to nonuniform cooling rates. From the product quality standpoint, such as interlaminar strength, dimensional accuracy etc., these stresses should be kept within allowable limits. In this study, a thermoviscoelastic finite element model was developed to predict residual stresses induced during the placement of thermoplastic composite tapes. The process, being continuous, was considered to be under a quasi steady state where process conditions do not change with respect to the moving roller. Relaxation of the residual stresses in previously laid layers was also allowed for. Results were obtained for both unidirectional and cross-ply laminates. They show the residual stress distributions through the thickness for a number of chosen sets of process parameters (e.g., roller velocity and heat input). Therefore, residual stresses in a laminate can be controlled by modifying these process parameters.
The Tangled Webs We Weave: Household Strategies to Co-Ordinate Home and Work
Authors: Jarvis Helen 
Published: July 2003

The connections between home and work are manifest in tensions which exist between individual employment mobility and the social and spatial situatedness of the household micro-economy. This nexus is a significant dimension of a growing number of dual earning households. At a fundamental level, the co-ordination of home and work hinges on opportunities and constraints pertaining to residential location and mobility and the way this issue is negotiated through the life-course. However, this is not simply determined by the many logistical difficulties associated with the co-ordination of more than one employment from a single residential location. Households are `situated' in place in a variety of ways which feed into strategies of relative mobility and attachment to place. It is suggested that the way that households accommodate the demands of home and work are constituted through a meshing together of the action spaces and social relations of individual household members in these spheres. In effect, household behaviour emerges from a `tangled web' of networks: of social and kin relations; of resource provision; and of information, knowledge and learning.This paper argues for the need to attend to the situatedness of household strategies that attempt to co-ordinate home and work. It suggests that this is achieved by observing the way strategies of relative mobility and attachment to place reproduce, and are reproduced through, networks within a locale. Existing concepts of strategy and network are combined and operationalised together through the interpretation of biographical narratives from interviews with couples from a sample of nuclear family households.
Process and Product Issues in the Evaluation of School Development Planning
Authors: O'hara Joe , McNamara Gerry 
Published: July 2003

In recent years, state funded, practitioner-led organizational improvement programmes have become increasingly common within the Irish education system. Central to this new model of public funding has been the demand for extensive evaluation of each programme, a demand that has raised a number of important theoretical and practical issues for programme evaluators. The issue addressed in this article is that of the difficulty of designing approaches to evaluation which can meet the cultural and organizational needs of schools, while at the same time providing evidence as to the effective or otherwise implementation of national educational policy. Initially, the article identifies and examines the tension that has arisen between programme funders' demand for an evaluation process that produces measurable 'outputs' and the programme participants' demand that the evaluation be sensitive to the specific cultural climate and needs of the organization under investigation. An approach to overcoming these conflicting demands arising out of a project where such problems became central to the process of evaluation is suggested. This approach grew out of the distinction drawn by Habermas (1972) between practical and emancipatory knowledge and was developed in light of Daly's (1997) application of this concept to research, in her identification of first and second order stories or narratives.
Private Revenge and Public Justice
Authors: CANTARELLA EVA 
Published: July 2003

This article intends to show that the study of the Homeric epics may be useful for understanding the historical roots of our modern institutions of Criminal Justice. The Iliad and the Odyssey (both the product of an oral tradition that lasted several centuries) were written down around the middle of the 8th century BC and describe the moral values and the social life of the Greek world of that period. The social organization that they describe was not yet a polis, and the law did not exist (at least in the modern sense of the word). Nevertheless, a set of social rules existed and was basically respected. The fundamental rule was an obligation to react to any offensive behaviour by taking revenge on the offender. The sanction for not taking revenge was `losing face'. But revenge was not a free exercise of violence. It was regulated by detailed rules, some of them considered so important that if a dispute arose concerning their violation, the Council of Elders settled the dispute, acting as the first documented body of jurors in western history. The Homeric epics, therefore, show the instruments and the effectiveness of social control in situations where a state does not exist, as well as the way - or one of the ways - in which a legal system may come into existence.
JAML, a novel protein with characteristics of a junctional adhesion molecule, is induced during differentiation of myeloid leukemia cells
Authors: Moog-Lutz Christel , Cavé-Riant Florence , Guibal Florence C. , Breau Marie A. , Di Gioia Yolande , Couraud Pierre Olivier , Cayre Yvon E. , Bourdoulous Sandrine , Lutz Pierre G. 
Published: July 2003

AbstractRetinoic acid induces clinical remission in acute promyelocytic leukemia (APL) by triggering differentiation of leukemia promyelocytes. Here, we have characterized a gene encoding a member of the immunoglobulin superfamily, among novel retinoic acid–induced genes identified in APL cells. This protein, which was named JAML (junctional adhesion molecule–like), contains 2 extracellular immunoglobulin-like domains, a transmembrane segment, and a cytoplasmic tail. JAML mRNA is expressed in hematopoietic tissues and is prominently expressed in granulocytes. The fact that JAML protein is localized at the cell plasma membrane in the areas of cell-cell contacts, whereas it is not detected at free cell borders, suggests that JAML is engaged in homophilic interactions. Furthermore, a conserved dimerization motif among JAM members was shown to be important for JAML localization at the cell membrane. Finally, exogenous expression of JAML in myeloid leukemia cells resulted in enhanced cell adhesion to endothelial cells. Altogether, our results point to JAML as a novel member of the JAM family expressed on leukocytes with a possible role in leukocyte transmigration.
Induction of cytotoxic T-cell responses against the oncofetal antigen-immature laminin receptor for the treatment of hematologic malignancies
Authors: Siegel Sandra , Wagner Andreas , Kabelitz Dieter , Marget Matthias , Coggin Joseph , Barsoum Adel , Rohrer James , Schmitz Norbert , Zeis Matthias 
Published: July 2003

AbstractThe oncofetal antigen immature laminin receptor protein (OFA-iLRP) is a highly conserved protein that is preferentially expressed in fetal tissues and in many types of cancer, including hematopoietic malignancies, whereas OFA-iLRP is not detectable on healthy differentiated adult cells. To investigate whether OFA-iLRP-specific cytotoxic T lymphocytes (CTLs) are capable of killing OFA-iLRP-expressing hematologic targets, CTLs were generated from healthy HLA-A*0201-positive volunteers by incubating T cells with autologous dendritic cells (DCs) transfected with OFA-iLRP RNA. OFA-iLRP-specific CTLs lysed HLA-A2+ OFA-iLRP+ tumor cells, including several lymphoma and leukemia cell lines, as well as fresh leukemic targets from patients with acute myeloid leukemia (AML) and chronic lymphatic leukemia (CLL), indicating that OFA-iLRP-derived peptides are naturally processed and presented by hematologic tumors. Healthy OFA-iLRP-negative target cells (CD14+ monocytes, activated B cells, DCs, bone marrow cells) were not attacked by OFA-iLRP-specific CTLs. Furthermore, in an established murine B-cell lymphoma model (A20), treatment with syngeneic DCs transfected with OFA-iLRP-coding RNA resulted in powerful antitumor effects in a significant portion of mice. For the first time, these data show that OFA-iLRP can be used as a target for T-cell-based immunotherapeutic strategies against hematologic malignancies. (Blood. 2003;102:4416-4423)
The amino terminal and E2F interaction domains are critical for C/EBPα-mediated induction of granulopoietic development of hematopoietic cells
Authors: D'Alo' Francesco , Johansen Lisa M. , Nelson Erik A. , Radomska Hanna S. , Evans Erica K. , Zhang Pu , Nerlov Claus , Tenen Daniel G. 
Published: July 2003

AbstractThe transcription factor C/EBPα (CCAAT/enhancer binding protein α) is critical for granulopoiesis. Gene disruption in mice blocks early granulocyte differentiation and disruption of C/EBPα function has been implicated in human acute myeloid leukemia (AML), but no systematic structure-function analysis has been undertaken to identify the mechanisms involved in C/EBPα-mediated granulocyte differentiation. Here we demonstrate that loss of either of 2 key regions results in disruption of C/EBPα granulocytic development: the amino terminus and specific residues residing on the non-DNA binding face of the basic region. Mutation of either results in loss of C/EBPα inhibition of E2F and down-regulation of c-Myc, but only mutation of the basic region results in loss of physical interaction with E2F. In contrast, while the amino terminal mutant retains the ability to interact with E2F, this mutant fails to bind a C/EBPα site efficiently, fails to activate C/EBPα target genes, and is also defective in inhibition of E2F activity. These results further emphasize the importance of inhibition of proliferative pathways in granulopoiesis and demonstrate that several regions of the C/EBPα protein are involved in this mechanism.
ADAMTS-13 cysteine-rich/spacer domains are functionally essential for von Willebrand factor cleavage
Authors: Soejima Kenji , Matsumoto Masanori , Kokame Koichi , Yagi Hideo , Ishizashi Hiromichi , Maeda Hiroaki , Nozaki Chikateru , Miyata Toshiyuki , Fujimura Yoshihiro , Nakagaki Tomohiro 
Published: July 2003

AbstractA severe lack of von Willebrand factor–cleaving protease (VWF-CP) activity can cause thrombotic thrombocytopenic purpura (TTP). This protease was recently identified as a member of the ADAMTS family, ADAMTS-13. It consists of a preproregion, a metalloprotease domain, a disintegrin-like domain, a thrombospondin type-1 motif (Tsp1), a cysteine-rich domain, a spacer domain, additional Tsp1 repeats, and CUB domains. To explore the structural and functional relationships of ADAMTS-13, we prepared here 13 sequential COOH-terminal truncated mutants and a single-point mutant (ArgGlyAsp [RGD] to ArgGlyGlu [RGE] in the cysteine-rich domain) and compared the activity of each mutant with that of the wild-type protein. The results revealed that the truncation of the cysteine-rich/spacer domains caused a remarkable reduction in VWF-CP activity. We also prepared immunoglobulin G (IgG) fractions containing inhibitory autoantibodies against ADAMTS-13 from plasma from 3 patients with acquired TTP, and we performed mapping of their epitopes using the aforementioned mutants. The major epitopes of these antibodies were found to reside within the cysteine-rich/spacer domains. These results suggest that the ADAMTS-13 cysteine-rich/spacer domains are essential for VWF-CP activity.