bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti–Glycoprotein VI Treatment Severely Compromises Hemostasis in Mice With Reduced α
2
β
1
Levels or Concomitant Aspirin Therapy
Authors: Grüner Sabine , Prostredna Miroslava , Aktas Barsom , Moers Alexandra , Schulte Valerie , Krieg Thomas , Offermanns Stefan , Eckes Beate , Nieswandt Bernhard
Published: October 2004

Background—

Platelet inhibition is a major strategy to prevent arterial thrombosis, but it is frequently associated with increased bleeding because of impaired primary hemostasis. The activating platelet collagen receptor, glycoprotein VI (GP VI), may serve as a powerful antithrombotic target because its inhibition or absence results in profound protection against arterial thrombosis but no major bleeding in mice.

Methods and Results—

Mice lacking (−/−) or expressing half-levels (+/−) of the other major platelet collagen receptor, integrin α
2
β
1
, were injected with the anti–GP VI antibody JAQ1 and analyzed on day 5. Anti–GP VI treatment resulted in a marked hemostatic defect in α
2
−/−
or α
2
+/−
mice, as shown by dramatically prolonged tail bleeding times. Platelet adhesion to collagen was studied in an ex vivo whole-blood perfusion system under high shear conditions. Weak integrin activation by thromboxane A
2
(TxA
2
) receptor stimulation restored defective adhesion of anti–GP VI–treated wild-type but not α
2
−/−
or α
2
+/−
platelets to collagen. This process required the simultaneous activation of the G
q
and G
13
signaling pathways, as demonstrated by use of the respective knockout strains. Conversely, inhibition of TxA
2
production by aspirin severely compromised hemostasis in anti–GP VI–treated or GP VI/Fc receptor γ-chain–deficient but not control mice.

Conclusions—

Anti–GP VI therapy may result in defective hemostasis in patients with reduced α
2
β
1
levels or concomitant aspirin therapy. These observations may have important implications for a potential use of anti–GP VI–based therapeutics in the prevention of cardiovascular disease.
Noninducibility of Atrial Fibrillation as an End Point of Left Atrial Circumferential Ablation for Paroxysmal Atrial Fibrillation
Authors: Oral Hakan , Chugh Aman , Lemola Kristina , Cheung Peter , Hall Burr , Good Eric , Han Jihn , Tamirisa Kamala , Bogun Frank , Pelosi Frank , Morady Fred
Published: October 2004

Background—

An anatomic approach of left atrial radiofrequency circumferential ablation (LACA) to encircle the pulmonary veins is often effective in eliminating paroxysmal atrial fibrillation (AF). However, no electrophysiological end points other than voltage abatement and/or conduction slowing or block across ablation lines have been used. It has been unclear whether noninducibility of AF is a clinically useful end point.

Methods and Results—

In 100 patients with paroxysmal AF (mean age, 55±10 years), LACA to encircle the left- and right-sided pulmonary veins was performed during AF, with additional ablation lines in the posterior left atrium and mitral isthmus, with an 8-mm-tip catheter. After completion of this lesion set, sinus rhythm was present, and AF lasting >60 seconds was not inducible in 40 patients (40%; group 1). The 60 patients in whom AF was still present or who still had inducible AF were randomly assigned to no further ablation (group 2; 30 patients) or to additional ablation lines along the left atrial septum, roof, and/or anterior wall where there were fractionated electrograms (group 3; 30 patients). In group 3, AF was rendered noninducible in 27 of 30 patients (90%). At a 6-month follow-up, 67% of patients in group 2 were free of AF without drug therapy compared with 86% of patients in group 3. (
P
=0.05, log-rank test). Left atrial flutter occurred in 17% and 27% of patients in each group, respectively (
P
=0.3).

Conclusions—

After LACA in patients with paroxysmal AF, AF usually can be rendered noninducible by additional ablation at sites of fractionated electrograms. Noninducibility of AF attained by additional electrogram-guided left atrial ablation may be associated with a better midterm clinical outcome than when AF is still inducible after LACA alone.
Novel Antiinflammatory Vascular Benefits of Systemic and Stent-Based Delivery of Ethylisopropylamiloride
Authors: Chen Yong-Xiang , Ma Xiaoli , Whitman Stewart , O’Brien Edward R.
Published: October 2004

Background—

Recently, we demonstrated that the amiloride derivative ethylisopropylamiloride (EIPA) limits vascular smooth muscle cell growth and migration. The purpose of the present experiments was to determine whether EIPA can also reduce the inflammatory component of atherogenesis and stent neointima formation.

Methods and Results—

To determine the effect of EIPA on the early inflammatory stages of atherogenesis, apolipoprotein E null mice (apoE
−/−
) fed an atherogenic diet received a subcutaneous pump infusion of either EIPA (3 mg · kg
−1
d
−1
) or the control vehicle for 4 weeks. The en face aortic area of atherosclerotic lesions and the subendothelial accumulation of macrophages were reduced by 46% and 38%, respectively, in EIPA-treated mice. Moreover, the number of vascular cell adhesion molecule-1 (VCAM-1) immunopositive lumenal endothelial cells was 59% less in the EIPA treatment group. In vitro, there was a concentration-dependent inhibition of lipopolysaccharide (LPS)-induced VCAM-1 expression with a corresponding 37% reduction in U-937 cell adhesion to endothelial cells. EIPA also reduced LPS-stimulated nuclear factor-κB (NF-κB) activation as reflected by a 66% reduction in NF-κB nuclear translocation. Finally, to test the effect of EIPA on the early inflammatory reaction to stent implantation, stents coated with jelly alone or jelly plus EIPA were implanted into rabbit iliac arteries. Four weeks later, the stent neointimal area, abundance of peristrut macrophages, and density of intimal smooth muscle cells were reduced by 38%, 47%, and 37%, respectively, for EIPA stents.

Conclusions—

EIPA downregulates endothelial cell activation of NF-κB and VCAM-1 expression and attenuates the early inflammatory stages of atherogenesis and stent intimal formation.
Low-Density Lipoprotein Triglycerides Associated With Low-Grade Systemic Inflammation, Adhesion Molecules, and Angiographic Coronary Artery Disease
Authors: März Winfried , Scharnagl Hubert , Winkler Karl , Tiran Andreas , Nauck Markus , Boehm Bernhard O. , Winkelmann Bernhard R.
Published: October 2004

Background—

Markers of systemic inflammation and LDL cholesterol (LDL-C) have been considered independent risk factors of coronary artery disease (CAD). We examined whether alterations of LDL metabolism not reflected by LDL-C were associated with low-grade inflammation, vascular injury, and CAD.

Methods and Results—

We studied 739 subjects with stable angiographic CAD and 570 matched control subjects in which CAD had been ruled out by angiography. The association of LDL triglycerides (LDL-TGs) (odds ratio [OR], 1.30; 95% CI, 1.19 to 1.43;
P
<0.001) with CAD was stronger than that of LDL-C (OR, 1.10; 95% CI, 1.00 to 1.21;
P
=0.047). The predictive value of LDL-TG for CAD was independent of LDL-C. “Sensitive” C-reactive protein (CRP), serum amyloid A, fibrinogen, interleukin 6, intercellular adhesion molecule-1 (ICAM-1), and vascular adhesion molecule-1 (VCAM-1) increased in parallel to LDL-TG. CRP, ICAM-1, and VCAM-1 were inversely related to LDL-C. To examine whether LDL-TGs were associated with the distribution of LDL subfractions, we studied 114 individuals with impaired fasting glucose, impaired glucose tolerance, or type 2 diabetes mellitus. In subjects with high LDL-TG, LDLs were depleted of cholesteryl esters (CEs), and VLDLs, IDLs, and dense LDLs were significantly elevated.

Conclusions—

Alterations of LDL metabolism characterized by high LDL-TG are related to CAD, systemic low-grade inflammation, and vascular damage. High LDL-TGs are indicative of CE-depleted LDL, elevated IDL, and dense LDL. LDL-TG may better reflect the atherogenic potential of LDL than LDL-C.
Percutaneous Mitral Annular Reduction Provides Continued Benefit in an Ovine Model of Dilated Cardiomyopathy
Authors: Byrne Melissa J. , Kaye David M. , Mathis Mark , Reuter David G. , Alferness Clif A. , Power John M.
Published: October 2004

Background—

Functional mitral valve regurgitation plays a key role in the symptomatic severity and progression of heart failure. In an ovine model of dilated cardiomyopathy, we examined the chronic functional consequences of mitral regurgitation reduction using a recently developed novel percutaneous mitral annular reduction (PMAR) device.

Methods and Results—

Fourteen adult sheep were paced right ventricularly at 180 to 190 bpm for 5 weeks, leading to the development of moderate mitral valve regurgitation. After echocardiographic, hemodynamic, and neurohormonal analysis, 9 animals underwent PMAR. All animals were subsequently paced for another 28 days, and a final echocardiographic and hemodynamic study was conducted. Animals that had undergone PMAR showed significantly increased negative and positive dP/dt, whereas pulmonary capillary wedge pressure and mitral valve regurgitation were significantly reduced compared with those at device implant despite continued pacing. In conjunction, significant improvements in plasma norepinephrine and brain natriuretic peptide were apparent.

Conclusions—

The application of PMAR in animals with pacing-induced dilated cardiomyopathy and functional mitral valve regurgitation resulted in continued improvements in hemodynamic and neurohormonal parameters.
Rate Dependence and Regulation of Action Potential and Calcium Transient in a Canine Cardiac Ventricular Cell Model
Authors: Hund Thomas J. , Rudy Yoram
Published: October 2004

Background—

Computational biology is a powerful tool for elucidating arrhythmogenic mechanisms at the cellular level, where complex interactions between ionic processes determine behavior. A novel theoretical model of the canine ventricular epicardial action potential and calcium cycling was developed and used to investigate ionic mechanisms underlying Ca
2+
transient (CaT) and action potential duration (APD) rate dependence.

Methods and Results—

The Ca
2+
/calmodulin-dependent protein kinase (CaMKII) regulatory pathway was integrated into the model, which included a novel Ca
2+
-release formulation, Ca
2+
subspace, dynamic chloride handling, and formulations for major ion currents based on canine ventricular data. Decreasing pacing cycle length from 8000 to 300 ms shortened APD primarily because of I
Ca(L)
reduction, with additional contributions from I
to1
, I
NaK
, and late I
Na
. CaT amplitude increased as cycle length decreased from 8000 to 500 ms. This positive rate–dependent property depended on CaMKII activity.

Conclusions—

CaMKII is an important determinant of the rate dependence of CaT but not of APD, which depends on ion-channel kinetics. The model of CaMKII regulation may serve as a paradigm for modeling effects of other regulatory pathways on cell function.
Comparison of Late Luminal Loss Response Pattern After Sirolimus-Eluting Stent Implantation or Conventional Stenting
Authors: Lemos Pedro A. , Mercado Nestor , van Domburg Ron T. , Kuntz Richard E. , O’Neill William W. , Serruys Patrick W.
Published: October 2004

Background—

We investigated the pattern of late luminal loss after sirolimus-eluting or bare stent implantation.

Methods and Results—

The study population comprised 238 patients treated with sirolimus-eluting stents and 526 patients treated with conventional stents. The distribution of late loss of sirolimus stents was largely skewed to the right and differed from the distribution for bare stents. When divided according to the presence of binary restenosis (diameter stenosis >50%), restenotic lesions in the bare stent group (26.0%) had a late loss of 1.40±0.64 mm and in the sirolimus group (7.9%) of 1.16±0.76 mm. Nonrestenotic lesions in the bare stent group had a late loss of 0.58±0.44 mm, whereas the late loss of nonrestenotic lesions in the sirolimus group remained close to zero (−0.05±0.33 mm). Differences between poststenting and follow-up measurements in the sirolimus group (late loss) resembled variations observed in repeated angiographic measurements, as assessed from a random sample of 30 segments measured repeatedly. After multivariate adjustment, stent type did not influence the degree of late loss in restenotic lesions. However, nonrestenotic bare stents had a significantly larger estimated luminal loss (0.58 mm; 95% CI, 0.52 to 0.65) than sirolimus-eluting stents, for which the predicted late loss was almost 0 (−0.04 mm; 95% CI, −0.10 to 0.02).

Conclusions—

The pattern of late loss after sirolimus-eluting stent implantation follows a peculiar behavior, different from lesions treated with conventional stents. Whether this is explained by an unusual statistical distribution or a biological all-or-none response of restenosis after sirolimus-eluting stenting remains to be investigated.
Novel Model of Constrictive Pericarditis Associated With Autoimmune Heart Disease in Interferon-γ–Knockout Mice
Authors: Afanasyeva Marina , Georgakopoulos Dimitrios , Fairweather DeLisa , Caturegli Patrizio , Kass David A. , Rose Noel R.
Published: October 2004

Background—

Constrictive pericarditis represents a serious hemodynamic syndrome that may lead to heart failure. Studies of its pathophysiological mechanisms have been impeded by the lack of an animal model.

Methods and Results—

Cardiac myosin–induced experimental autoimmune myocarditis in interferon (IFN)-γ–knockout (KO) mice results in increased cardiac inflammation and development of severe grossly detectable pericarditis. Using in vivo pressure-volume studies, we found that the acute phase of experimental autoimmune myocarditis in IFN-γ–KO mice was characterized by reduced left ventricular (LV) volumes compared with wild-type mice. The KO mice exhibited a classic restrictive/constrictive phenotype with decreased cardiac output, increased chamber stiffness, preserved ejection fraction, and impaired diastolic filling, characterized by reduced deceleration time and pressure tracings showing the square root sign similar to that observed in clinical cases of constrictive pericarditis. This phenotype was not associated with the severity of myocarditis but correlated with the presence of grossly detectable adhesive pericarditis present only in the KO group and characterized by increased pericardial inflammation and fibrosis. Comparison of IFN-γ–KO and wild-type mice matched for the severity of myocardial disease further confirmed that pericarditis, and not myocarditis, was responsible for smaller LV volumes, reduced cardiac output, increased cardiac stiffness, and increased peak filling rate adjusted for end-diastolic volumes in KO mice.

Conclusions—

Autoimmune heart disease in IFN-γ–KO mice results in increased pericardial inflammation and fibrosis, leading to constrictive phenotype during the acute phase of disease. It represents a novel animal model of constrictive pericarditis.
Management of Hypertension in the Very Elderly Patient
Authors: Elliott William J.
Published: October 2004

This Hypertension Grand Rounds discusses pharmacological treatment of hypertension in individuals who have survived 9 decades on earth. This rapidly growing group of relatively active and healthy elderly people is at high risk for hypertension, its treatment, and its adverse consequences, including stroke and heart failure. In this age group, the most common abnormality is elevated systolic blood pressure, which is much more predictive of stroke and heart disease death after 53 years of age. With the possible exception of the Antihypertensive and Lipid Lowering to prevent Heart Attack Trial (ALLHAT), recent clinical trials have emphasized the overriding importance of lowering blood pressure rather than the specific agent chosen to begin therapy. In 1999, a metaanalysis of 7 clinical trials that enrolled 1670 subjects >80 years of age indicated that active antihypertensive drug therapy significantly reduced stroke by 34% and heart failure by 39% but was associated with a nonsignificant 6% increase in mortality. The HYpertension in the Very Elderly Trial (HYVET) will enroll 2100 patients >80 years of age and will compare 2 groups randomized to indapamide±perindopril versus placebo±placebo for incident stroke during 5 years of follow-up. This study should answer lingering questions about whether active antihypertensive therapy is associated with a major and significant reduction in cardiovascular morbidity and mortality in this age group as it clearly does in younger hypertensives. Its choice of a diuretic as initial therapy is consistent with other trials, but chlorthalidone is the drug with the most compelling evidence in large US trials that included very elderly patients.
Impairment of PI3-K/Akt Pathway Underlies Attenuated Endothelial Function in Aorta of Type 2 Diabetic Mouse Model
Authors: Kobayashi Tsuneo , Taguchi Kumiko , Yasuhiro Takenouchi , Matsumoto Takayuki , Kamata Katsuo
Published: October 2004

The phosphatidylinositol 3-kinase (PI3-K) pathway, which activates serine/threonine protein kinase Akt, enhances endothelial nitric oxide synthase (eNOS) phosphorylation and nitric oxide (NO) production. We investigated the involvement of the PI3-K/Akt pathway in the relaxation responses to acetylcholine (ACh) and clonidine in a new type 2 diabetic model (streptozotocin plus nicotinamide-induced diabetic mice). Plasma glucose and insulin levels were significantly elevated in our model, and intravenous glucose tolerance tests revealed clear abnormalities in glucose tolerance and insulin responsiveness. Although in our model the ACh-induced relaxation and NO
x
−
(NO
2
−
+NO
3
−
)/cGMP production were unchanged, the clonidine-induced and insulin-induced relaxations and NO
x
−
/cGMP production were all greatly attenuated. In control mice, the clonidine-induced and insulin-induced relaxations were each abolished by LY294002 and by Wortmannin (inhibitors of PI3-K), and also by Akt-inhibitor treatment. The ACh-induced relaxation was unaffected by such treatments in either group of mice. The expression level of total Akt protein was significantly decreased in the diabetic mice aorta, but those for the p85 and p110γ subunits of PI3-K were not. The clonidine-induced Ser-473 phosphorylation of Akt through PI3-K was significantly decreased in our model; however, that induced by ACh was not. These results suggest that relaxation responses and NO production mediated via the PI3-K/Akt pathway are decreased in this type 2 diabetic model. This may be a major cause of endothelial dysfunction (and the resulting hypertension) in type 2 diabetes.
Vascular Response to Angiotensin II Predicts Long-Term Prognosis in Patients Undergoing Coronary Artery Bypass Grafting
Authors: van der Harst Pim , Volbeda Meint , Voors Adriaan A. , Buikema Hendrik , Wassmann Sven , Böhm Michael , Nickenig Georg , van Gilst Wiek H.
Published: October 2004

Persistent activation of the renin-angiotensin system leads to downregulation of the angiotensin type-1 receptor, and consequently, to a decreased response to exogenous angiotensin II. In the present study, we investigated the association of angiotensin II responsiveness to clinical outcome after coronary artery bypass grafting (CABG). We studied the responsiveness to exogenous angiotensin II in human thoracic artery preparations of 114 CABG patients. Mean duration of follow-up was 7.3±0.1 years, during which 21 patients experienced a cardiovascular event. A diminished response to angiotensin II remained in multivariate Cox regression analysis, after adjustment for sex, age, blood pressure, and number of diseased coronary arteries, the strongest predictor for cardiovascular events (relative risk, 3.37 [95% confidence interval, 1.20 to 9.51];
P
=0.022). Furthermore, diminished response to angiotensin II was associated with an increased mean arterial pressure (102.85±1.38 versus 97.40±1.37;
P
=0.003) and a nonsignificant increase in angiotensin-converting enzyme activity, suggestive for a persistently activated renin-angiotensin system. In conclusion, these results suggest that in patients undergoing CABG, a diminished vascular responsiveness of the thoracic artery to exogenous angiotensin II is related to an increased risk of future cardiovascular events.
Cognitive Map Formation Through Sequence Encoding by Theta Phase Precession
Authors: Wagatsuma Hiroaki , Yamaguchi Yoko
Published: October 2004

The rodent hippocampus has been thought to represent the spatial environment as a cognitive map. The associative connections in the hippocampus imply that a neural entity represents the map as a geometrical network of hippocampal cells in terms of a chart. According to recent experimental observations, the cells fire successively relative to the theta oscillation of the local field potential, called theta phase precession, when the animal is running. This observation suggests the learning of temporal sequences with asymmetric connections in the hippocampus, but it also gives rather inconsistent implications on the formation of the chart that should consist of symmetric connections for space coding.

In this study, we hypothesize that the chart is generated with theta phase coding through the integration of asymmetric connections. Our computer experiments use a hippocampal network model to demonstrate that a geometrical network is formed through running experiences in a few minutes. Asymmetric connections are found to remain and distribute heterogeneously in the network. The obtained network exhibits the spatial localization of activities at each instance as the chart does and their propagation that represents behavioral motions with multidirectional properties. We conclude that theta phase precession and the Hebbian rule with a time delay can provide the neural principles for learning the cognitive map.
How Many Clusters? An Information-Theoretic Perspective
Authors: Still Susanne , Bialek William
Published: October 2004

Clustering provides a common means of identifying structure in complex data, and there is renewed interest in clustering as a tool for the analysis of large data sets in many fields. A natural question is how many clusters are appropriate for the description of a given system. Traditional approaches to this problem are based on either a framework in which clusters of a particular shape are assumed as a model of the system or on a two-step procedure in which a clustering criterion determines the optimal assignments for a given number of clusters and a separate criterion measures the goodness of the classification to determine the number of clusters. In a statistical mechanics approach, clustering can be seen as a trade-off between energy- and entropy-like terms, with lower temperature driving the proliferation of clusters to provide a more detailed description of the data. For finite data sets, we expect that there is a limit to the meaningful structure that can be resolved and therefore a minimum temperature beyond which we will capture sampling noise. This suggests that correcting the clustering criterion for the bias that arises due to sampling errors will allow us to find a clustering solution at a temperature that is optimal in the sense that we capture maximal meaningful structure—without having to define an external criterion for the goodness or stability of the clustering. We show that in a general information-theoretic framework, the finite size of a data set determines an optimal temperature, and we introduce a method for finding the maximal number of clusters that can be resolved from the data in the hard clustering limit.
A Complex-Valued RTRL Algorithm for Recurrent Neural Networks
Authors: Goh Su Lee , Mandic Danilo. P.
Published: October 2004

A complex-valued real-time recurrent learning (CRTRL) algorithm for the class of nonlinear adaptive filters realized as fully connected recurrent neural networks is introduced. The proposed CRTRL is derived for a general complex activation function of a neuron, which makes it suitable for nonlinear adaptive filtering of complex-valued nonlinear and nonstationary signals and complex signals with strong component correlations. In addition, this algorithm is generic and represents a natural extension of the real-valued RTRL. Simulations on benchmark and real-world complex-valued signals support the approach.
A Learning Rule for Local Synaptic Interactions Between Excitation and Shunting Inhibition
Authors: Mo Chun-Hui , Gu Ming , Koch Christof
Published: October 2004

The basic requirement for direction selectivity is a nonlinear interaction between two different inputs in space-time. In some models, the interaction is hypothesized to occur between excitation and inhibition of the shunting type in the neuron's dendritic tree. How can the required spatial specificity be acquired in an unsupervised manner? We here propose an activity-based, local learning model that can account for direction selectivity in visual cortex based on such a local veto operation and that depends on synaptically induced changes in intracellular calcium concentration. Our biophysical simulations suggest that a model cell with our learning algorithm can develop direction selectivity organically after unsupervised training. The learning rule is also applicable to a neuron with multiple-direction-selective subunits and to a pair of cells with opposite-direction selectivities and is stable under different starting conditions, delays, and velocities.
Mean Field and Capacity in Realistic Networks of Spiking Neurons Storing Sparsely Coded Random Memories
Authors: Curti Emanuele , Mongillo Gianluigi , Camera Giancarlo La , Amit Daniel J.
Published: October 2004

Mean-field (MF) theory is extended to realistic networks of spiking neurons storing in synaptic couplings of randomly chosen stimuli of a given low coding level. The underlying synaptic matrix is the result of a generic, slow, long-term synaptic plasticity of two-state synapses, upon repeated presentation of the fixed set of the stimuli to be stored. The neural populations subtending the MF description are classified by the number of stimuli to which their neurons are responsive (multiplicity). This involves 2p + 1 populations for a network storing p memories. The computational complexity of the MF description is then significantly reduced by observing that at low coding levels (f), only a few populations remain relevant: the population of mean multiplicity –pf and those of multiplicity of order √pf around the mean.

The theory is used to produce (predict) bifurcation diagrams (the onset of selective delay activity and the rates in its various stationary states) and to compute the storage capacity of the network (the maximal number of single items used in training for each of which the network can sustain a persistent, selective activity state). This is done in various regions of the space of constitutive parameters for the neurons and for the learning process. The capacity is computed in MF versus potentiation amplitude, ratio of potentiation to depression probability and coding level f. The MF results compare well with recordings of delay activity rate distributions in simulations of the underlying microscopic network of 10,000 neurons.
The critical period of disasters: Insights from sense-making and psychoanalytic theory
Authors: Stein Mark
Published: October 2004

The purpose of this article is to deepen our understanding of the period during which a disaster unfolds, here called the ‘critical period’. Previous research has shown cases in which sense-making is essential for survival during this period, but it is argued here that there are other cases in which sense-making compounds the problems. Drawing on psychoanalytic theory, the capacity for anxiety toleration is postulated as a moderating variable that influences whether correct sense can be made of the situation, and, in turn, whether the likelihood of survival will increase. Implications for theory are examined.
The 1996 Mount Everest climbing disaster: The breakdown of learning in teams
Authors: Kayes D. Christopher
Published: October 2004

Qualitative analysis of the events leading to the deaths of eight climbers on Mt Everest in 1996 illustrates the breakdown of learning in teams. The analysis contributes to research on the role of teams in organizational disasters by considering team learning and development as the basis for success in complex and changing organizations. Multiple qualitative methods reveal three precursors associated with the breakdown of learning in teams: narrowly defined purpose, directive leadership and failure to sense an ill-defined problem. Findings have implications for normal disasters and sense-making, performance in short-term project teams, and organizational learning.
Mothers and sons and Russian literature
Authors: Smith G. S.
Published: October 2004

Using basic information about the history of the Russian family to set up some elementary points of reference, the lecture examines the ways in which a series of eminent Russian male authors from the eighteenth century to the present day have represented in their fiction the relationship between mothers and their adult sons. They are found to have treated the mother figure in three main ways: elimination, idealization and demonization.
Marianne: from Medusa to Messalina
Authors: Kidd William
Published: October 2004

The use of ‘monstrous’, anxiety-generating imagery (tropes of the mythological Medusa or the Hydra) to demonize opponents was a marked feature of political caricature and national propaganda on different points in the ideological spectrum, from the French revolutionary and counter-revolutionary period, through the ‘Commune’ (1871), to the First and Second World Wars. Using examples from contemporary lithography, literature, the press and official sources, my paper argues that this propaganda owed its ubiquity and polyvalence to the presence of powerful associations, sometimes unstated, sometimes explicit, between the revolutionary ‘Medusa’ and the guillotine, and the other supreme socio-medical hantise of the period, the threat of venereal infection.
The Effects of Weld Geometry and Glass-fiber-orientation on the Mechanical Performance of Joints - Part II: Kinetics of Glass-fiber-orientation and Mechanical Performance
Authors: Kagan Val A. , Roth Christopher
Published: October 2004

The mechanical performance of injection-molded short glass-fiber-reinforced thermoplastic components is anisotropic and is highly dependent on the fiber-orientation and distribution. Similarly, the bulk and short and long-term mechanical performance at the weld is influenced by these fibers and the specific welding technology used as related to melt-pool formation.

The purpose of this analysis is to show:

1. the short-fiber-orientation (analytical and simulation data) and distribution at the prewelded bead, ribs, and wall areas;

2. advantages of SigmaSoft injection-molding simulation software, which utilizes full threedimensional fiber representation of any molded part;

3. the mechanical performance of welds with optimized geometry (US Patent 6,447,866).

Findings on the mechanical performance of butt-joints with different designs and localized geometry will help designers and technicians with plastic part design optimization. In a previous ANTEC paper (Part I) (Kagan, V.A. and Roth, C. (2002). The Effects of Weld Geometry and Glass-Fiber Orientation on the Mechanical Performance of Joints - Part I: Kinetics of Glass-fiber-orientation and Performance at Bulk and Weld Areas, Design Issues, In: ANTEC Proceedings), we related these findings to the kinetics of welds and part design issues for straight and T-type butt-joints.
An Elasto-plastic Stress Analysis of Aluminum Metal-Matrix Composite Beam Subjected to Transverse Linearly Distributed Load
Authors: Esendemir Ümran , Öndürücü Ayse
Published: October 2004

An analytical elasto-plastic stress analysis is carried out on metal-matrix composite beams supported from two ends under transverse linearly distributed load. The composite beam consists of stainless steel fiber and aluminum matrix. The material is assumed to be perfectly plastic for the elasto-plastic solution. The expansion of the plastic region and the residual stress component of x and τxy are determined for 0, 30, 45, 60, and 90 orientation angles. The yielding begins at the upper and lower surfaces of the beam at the same distances from the ends. The intensity of residual stress component of x is maximum at the upper and lower surfaces but residual stress component of τxy is maximum on the x axis of the beam. The strength of the beam is increased by residual stresses.
Thermal Buckling of Orthotropic Plates with Angle Crack
Authors: Sahin Omer Sinan , Avci Ahmet , Kaya Sami
Published: October 2004

In this study, thermal buckling behaviors of the composite square plates consisting of antisymmetric four laminates with angle crack are examined. Finite element method is used for the solution. First critical buckling loads of an orthotropic plate without crack subjected to unidirectional compression are found. Constraint conditions have been taken two edge clamped and the other edges are free. The thickness of plate is 2mm (each layer has 0.5mm thickness). Thermal buckling behaviors of this plate are examined and critical temperatures are determined. Values have been given in the graphs and discussions are presented in the conclusion.
Study of the Bending Properties in Gas-assisted Injection Molded Fiber-reinforced Nylon Parts
Authors: Chien Rean Der , Cheng Nien-Tien , Chen Shia-Chung
Published: October 2004

Glass fiber-reinforced Nylon plate parts designed with gas channels having five different types of cross section but with the same section were gas-assisted injection molded (GAIM). Effects of glass fiber content and geometrical factors introduced by various section shapes and the associated dimensions of gas channels on bending properties of GAIM parts were investigated via a bending test. Test results were also compared with those of conventional injection molded parts. Based on the measured results, it is found that gas-assisted injection molded parts show better bending properties including flexural strength, absorbed energy and bending stiffness than conventional injection molded parts. Alternatively, bending performance of GAIM parts increases when the content of glass fiber is increased. However, the fiber content of 15% has pretty good efficiency of bending performance. Meanwhile, for five gas channel designs, both gas channel designs attached with top rib (shapes D and E) show the higher bending stiffness and maximum bending load, correspondingly. So, generally speaking, these two gas channel designs provide the best enhancement in bending performance, however, parts with semicircular and rectangular gas channel designs (shapes A and B) can absorb more bending energy than the other designs. Alternatively, the flexural strength shows only slight influence from gas channel design, the deviation from average values less than 10%. The present study provides part designers with a design guideline for choosing the most effective gas channel design and fiber content to achieve a specific objective of part structural performance.
Resin Infusion Between Double Flexible Tooling: Evaluation of Process Parameters
Authors: Thagard J. R. , Okoli O. I. , Liang Z.
Published: October 2004

Manufacturers of lean weight vehicular structures are discovering the advantages of utilizing the high strength to weight ratios found in composite materials. However, traditional closed mold techniques require a long cycle time and relatively expensive tooling. This paper reports on a new technique called Resin Infusion between Double Flexible Tooling (RIDFT). In this innovative process, the resin infusion and resin-fiber wetting are finished between two flexible tools in a two dimensional flat shape and then the entire wetted reinforcement and flexible tooling is formed into a specified part shape by using a vacuum. This process avoids complex resin flow and mold filling issues and saves mold preparation and fiber stacking time. Using a RIDFT prototype, several components were produced. A larger industrial RIDFT machine was constructed to establish its viability for large component manufacture. An evaluation of production parameters, including infusion pressure, resin temperature, number of fiber layers and hardener content, ascertained their effect on mechanical properties and infusion times for the manufactured parts. The interaction between the hardener and fiber layers were found to directly affect tensile strength. The interaction between hardener and infusion pressure was also shown to affect tensile strength.
Soft regulation and the subtle transformation of states: the case of EU employment policy
Authors: Jacobsson Kerstin
Published: October 2004

This article studies the soft regulation developed in the field of EU employment policy from the late 1990s onwards, a type of policy co-ordination that has been termed the ‘Open Method of Coordination’. It focuses on particular regulatory mechanisms, in the section entitled ‘Discursive regulatory mechanisms’, built into this ‘soft’ system of governance, which are related to language use and knowledge making. These include: joint language use (Eurodiscourse); the building of a common knowledge base (including collection and standardization of statistics); the strategic use of comparisons and evaluations; the systematic editing and diffusion of knowledge, combined with social pressure and time pressure. It is argued that these measures together constitute a systematic system of governance with the potential to transform the practices of the member states and thus add to the integration process, albeit by a partly different kind of dynamic than regulation and integration by hard law.
Mechanisms of poverty alleviation: anti-poverty effects of non-means-tested and means-tested benefits in five welfare states
Authors: Nelson Kenneth
Published: October 2004

Substantial cross-national differences in poverty alleviation are well documented. But the extent to which different parts of the social transfer system account for this variation is still relatively unexamined. This paper analyses the redistributive effects of specific social policy institutions in a comparative perspective. The main question is to what extent non-means-tested entitlements and means-tested benefits reduce relative economic poverty in different institutional settings. It is shown that the structure of non-means-tested benefits is more important than that of meanstested benefits in explaining differences in poverty alleviation across countries. The paper also presents a new method for estimating the anti-poverty effects of separate parts of the social transfer system. This method decomposes the anti-poverty effects of a set of social transfers into independent and combined effects, which produces more valid results than prevalent methods used to assess the impact of a particular transfer on poverty. The countries included in this study are Canada, Germany, Sweden, the United Kingdom and the United States. The empirical analyses are based on data from the Social Citizenship Indicators Programme (SCIP) and Luxembourg Income Study (LIS) describing the situation in the mid-1990s.
Gender policies and the position of women in the police force in European countries
Authors: Van der Lippe Tanja , Graumans Anne , Sevenhuijsen Selma
Published: October 2004

There is still a wide gap between the participation of men and women in the police force. In this article, we discuss existing barriers to gender policies aimed at improving the situation of women in the police force in four European countries, namely, Sweden, Spain (more specifically, Catalonia), Austria, and the Netherlands. Interviews as well as an expert meeting have been held to gain insight into the barriers to gender equality. As it turns out, gender mainstreaming policies form an important key to the process of raising women’s position in the police force. Although organizational structures have to change before cultural issues can be addressed, the most important existing barrier to gender equality proves to be the culture within the organization: in all four countries we studied, the police force is still male-dominated. With respect to gender equality in the police force, Sweden shows itself to be a front runner, followed by the Netherlands, Austria, and latecomer Catalonia.
European Social Citizenship and Gender: The Part-time Work Directive
Authors: Bleijenbergh Inge , de Bruijn Jeanne , Bussemaker Jet
Published: October 2004

This article considers whether the development of European rights for workers implies a European social citizenship. It analyses the debate during the preparation and adoption of the EU Directive on part-time work in 1997, which guarantees part-time workers (who are primarily women) the same pay and working conditions as full-time workers. Was the concept of social citizenship discussed during its preparation and adoption? What kind of gender equality was involved: are women granted equal access to the European market or equal outcomes? We conclude that the Directive involves industrial rather thansocial citizenship, but ideals of social citizenship were nevertheless at stake during its preparation.
‘Become the man that women desire’: gender identities and dominant discourses in email advertising language
Authors: Mullany Louise
Published: October 2004

Haraway (1985, 1991) presents a futuristic, utopian vision of a gender-free space as the distinction between human and machine becomes indistinct in the age of global technologization. This article explores how such an idealized perspective corresponds with the current reality of gender identity in cyberspace. The fluidity of gender identities is examined by conducting a linguistic analysis of the strategies advertisers use to address their targeted subjects via electronic mail (email). The option of gender neutrality is available within email as a user’s gender identity can be concealed by a non-gender specific user name, and data are analysed from a series of messages sent to a non-gender specific email account hosted by one of the world’s largest email service providers. While the fluidity of gender identity can be clearly observed, a quantitative analysis reveals that the targeted gender identity is one of heterosexual masculinity. Despite recent statistics that women now use the Internet just as frequently as men, disembodied advertisers can be viewed constructing fictional personae to entice male recipients to pay for heterosexual pornography or products to enhance male heterosexual performance. When female gender identity is invoked within these messages, women are viewed as passive and consumable (Mills, 1995). Therefore, instead of producing an environment where distinctions between genders are diminished as Haraway hoped, binary oppositions are intensified as the dominant gender discourses of femininity and masculinity are produced and reproduced through these messages.
HPC Productivity: An Overarching View
Authors: Kepner Jeremy
Published: October 2004

The Defense Advanced Research Projects Agency (DARPA) High Productivity Computing Systems (HPCS) program is focused on providing a new generation of economically viable high productivity computing systems for national security and for the industrial user community. The value of a high performance computing (HPC) system to a user includes many factors, such as execution time on a particular problem, software development time, direct hardware costs, and indirect administrative and maintenance costs. This special issue, which focuses on HPC productivity, brings together, for the first time, a series of novel papers written by several distinguished authors who share their views on this topic. The topic of productivity in HPC is very new and the authors have been encouraged to speculate. The goal of this first paper is to present an overarching context and framework for the other papers and to define some common ideas that have emerged in considering the problem of HPC productivity. In addition, this paper defines several characteristic HPC workflows that are useful for understanding how users exploit HPC systems, and discusses the role of activity and purpose benchmarks in establishing an empirical basis for HPC productivity.
Measuring High Performance Computing Productivity
Authors: Faulk Stuart , Gustafson John , Johnson Philip , Porter Adam , Tichy Walter , Votta Lawrence
Published: October 2004

One key to improving high performance computing (HPC) productivity is to find better ways to measure it. We define productivity in terms of mission goals, i.e. greater productivity means that more science is accomplished with less cost and effort. Traditional software productivity metrics and computing benchmarks have proven inadequate for assessing or predicting such end-to-end productivity. In this paper we introduce a new approach to measuring productivity in HPC applications that addresses both development time and execution time. Our goal is to develop a public repository of effective productivity benchmarks that anyone in the HPC community can apply to assess or predict productivity.
Purpose-Based Benchmarks
Authors: Gustafson J.
Published: October 2004

We define an approach to benchmarking, “purpose-based benchmarks”, which explicitly and comprehensively measures the ability of a computing system to reach a goal of human interest. This contrasts with the traditional approach of defining a benchmark as a task to be timed, or as the rate at which some activity is performed. Purpose-based benchmarks are more difficult to create than traditional benchmarks, but have a profound advantage that makes them well worth the trouble: they provide a well-defined quantitative measure of the productivity of a computer system.
Productivity in High Performance Computing
Authors: Kuck David J.
Published: October 2004

HPC (high performance computing) has been a popular acronym for decades, and has been applied to many types of architectures, software and applications. The “P” has recently been overloaded to mean both performance and productivity. We present a survey of today’s performance and productivity situation relative to the constituent HPC hardware and software components, and provide some analysis of current controversies and open issues. Since “HPC” will continue to be applied to whatever is happening at the leading edge of computer architecture, system and development software, and algorithms and applications, there is no hope or need to define or clean up terminology (this paper uses HPC to denote hiperc and hiproc, with context determining meaning). Instead, it is important to clarify the whys and wherefores of the state of the art, in order to focus on new work that will maximize future benefits. This paper gives a broad discussion of HPC productivity in terms of effective architectures, run-time system software, and applications development tools. There are costs and trade-offs associated with each of these, and in fact multiple marketplaces consume these products. The range of demands placed on HPC, by owners and users of systems ranging from public research laboratories to private scientific and engineering companies, enrich the topic with many competing technologies and approaches. Rather than expecting to eliminate each other in the short run, these HPC competitors should be learning from one another in order to stay in the race. It seems clear that the dynamics between “commodity” and “custom” building blocks will remain at the center of HPC debates for some time, and indeed these competing forces form the engine of improvement for overall HPC cost/effectiveness.