bluuebunny/crossref_metadata_2025 huggingface dataset:
CHALLENGES IN PARALLEL GRAPH PROCESSING
Authors: LUMSDAINE ANDREW , GREGOR DOUGLAS , HENDRICKSON BRUCE , BERRY JONATHAN
Published: April 2007

Graph algorithms are becoming increasingly important for solving many problems in scientific computing, data mining and other domains. As these problems grow in scale, parallel computing resources are required to meet their computational and memory requirements. Unfortunately, the algorithms, software, and hardware that have worked well for developing mainstream parallel scientific applications are not necessarily effective for large-scale graph problems. In this paper we present the inter-relationships between graph problems, software, and parallel hardware in the current state of the art and discuss how those issues present inherent challenges in solving large-scale graph problems. The range of these challenges suggests a research agenda for the development of scalable high-performance software for graph problems.
Using Model-based Clustering to Improve Predictions for Queueing Delay on Parallel Machines
Authors: Brevik John , Nurmi Daniel , Wolski Rich
Published: April 2007

Most space-sharing parallel computers presently operated by production high-performance computing centers use batch-queuing systems to manage processor allocation. In many cases, users wishing to use these batch-queued resources may choose among different queues (charging different amounts) potentially on a number of machines to which they have access. In such a situation, the amount of time a user's job will wait in any one batch queue can be a significant portion of the overall time from job submission to job completion. It thus becomes desirable to provide a prediction for the amount of time a given job can expect to wait in the queue. Further, it is natural to expect that attributes of an incoming job, specifically the number of processors requested and the amount of time requested, might impact that job's wait time.

In this work, we explore the possibility of generating accurate predictions by automatically grouping jobs having similar attributes using model-based clustering. Moreover, we implement this clustering technique for a time series of jobs so that predictions of future wait times can be generated in real time.

Using trace-based simulation on data from 7 machines over a 9-year period from across the country, comprising over one million job records, we show that clustering either by requested time, requested number of processors, or the product of the two generally produces more accurate predictions than earlier, more naive, approaches and that automatic clustering outperforms administrator-determined clustering.
IMPROVED RUNTIME AND TRANSFER TIME PREDICTION MECHANISMS IN A NETWORK ENABLED SERVERS MIDDLEWARE
Authors: JEANNOT EMMANUEL , SEYMOUR KEITH , YARKHAN ASYM , DONGARRA JACK J.
Published: April 2007

In this paper we address the problem of accurately estimating the runtime and communication time of a client request in a Network Enabled Server (NES) middleware such as GridSolve. We use a template based model for the runtime estimation and a client-server communication test for the transfer time estimation. We implement these two mechanisms in GridSolve and test them on a real testbed. Experiments show that they allow for significant improvement in terms of client execution time on various scenarios.
Open MPI: A High Performance, Flexible Implementation of MPI Point-to-Point Communications
Authors: Graham Richard L. , Barrett Brian W. , Shipman Galen M. , Woodall Timothy S. , Bosilca George
Published: April 2007

Open MPI's point-to-point communications abstractions, described in this paper, handle several different communications scenarios, with a portable, high-performance design and implementation. These abstractions support two types of low-level communication protocols – general purpose point-to-point communications, like the OpenIB interface, and MPI-like interfaces, such as Myricom's MX library. Support for the first type of protocols makes use of all communications resources available to a given application run, with optional support for communications error recovery. The latter provides a interface layer, relying on the communications library to guarantee correct MPI message ordering and matching. This paper describes the three point-to-point communications protocols currently supported in the Open MPI implementation, supported with performance data. This includes comparisons with other MPI implementations using the OpenIB, MX, and GM communications libraries.
LANGUAGES FOR HIGH-PRODUCTIVITY COMPUTING: THE DARPA HPCS LANGUAGE PROJECT
Authors: LUSK EWING , YELICK KATHERINE
Published: April 2007

We present a summary of the current state of DARPA's HPCS language project. We describe the challenges facing any new language for scalable parallel computing, including the strong competition presented by MPI and the existing Partitioned Global Address Space (PGAS) Languages. We identify some of the major features of the proposed languages, using MPI and the PGAS languages for comparison, and describe the opportunities for higher productivity along with the implementation challenges. Finally, we present the conclusions of a recent workshop in which a concrete plan for the next few years was proposed.
AN EXPLORATION OF NON-ASYMPTOTIC LOW-DENSITY, PARITY CHECK ERASURE CODES FOR WIDE-AREA STORAGE APPLICATIONS
Authors: PLANK JAMES S. , THOMASON MICHAEL G.
Published: April 2007

As peer-to-peer and widely distributed storage systems proliferate, the need to perform efficient erasure coding, instead of replication, is crucial to performance and efficiency. Low-Density Parity-Check (LDPC) codes have arisen as alternatives to standard erasure codes, such as Reed-Solomon codes, trading off vastly improved decoding performance for inefficiencies in the amount of data that must be acquired to perform decoding. The scores of papers written on LDPC codes typically analyze their collective and asymptotic behavior. Unfortunately, their practical application requires the generation and analysis of individual codes for finite systems.

This paper attempts to illuminate the practical considerations of LDPC codes for peer-to-peer and distributed storage systems. The three main types of LDPC codes are detailed, and a huge variety of codes are generated, then analyzed using simulation. This analysis focuses on the performance of individual codes for finite systems, and addresses several important heretofore unanswered questions about employing LDPC codes in real-world systems.
DAMPING OF ULTRASOFT FERMIONS IN FINITE TEMPERATURE QED
Authors: ABADA A. , BOUAKAZ K. , DEGHICHE D.
Published: April 2007

We calculate the fermion damping rates to second order in powers of the external momentum in the context of QED at finite temperature using the hard-thermal-loop summation scheme. We find the coefficients of zeroth and first orders finite whereas that of second-order logarithmically infrared sensitive. The calculation is done in covariant gauge and the result is independent of gauge fixing.
HAWKING TUNNELING RADIATION OF BLACK HOLES IN de SITTER AND ANTI-de SITTER SPACETIMES
Authors: JIANG QING-QUAN , LI HUI-LING , YANG SHU-ZHENG , CHEN DE-YOU
Published: April 2007

Applying Parikh–Wilczek's semiclassical quantum tunneling method, we investigate the tunneling radiation characteristics of a torus-like black hole and Kerr–Newman–Kausya de Sitter black hole. Both black holes have the cosmological constant Λ, but a torus-like black hole is in anti-de Sitter spacetime and the other black hole is in de Sitter spacetime. The derived results show that the tunneling rate is related to the change of Bekenstein–Hawking entropy, and the factual radiated spectrum is not precisely thermal, but is consistent with an underlying unitary theory, which gives a might explanation to the paradox of black hole information lost.
CUBIC SPLINE COALESCENCE FRACTAL INTERPOLATION THROUGH MOMENTS
Authors: CHAND A. K. B. , KAPOOR G. P.
Published: April 2007

This paper generalizes the classical cubic spline with the construction of the cubic spline coalescence hidden variable fractal interpolation function (CHFIF) through its moments, i.e. its second derivative at the mesh points. The second derivative of a cubic spline CHFIF is a typical fractal function that is self-affine or non-self-affine depending on the parameters of the generalized iterated function system. The convergence results and effects of hidden variables are discussed for cubic spline CHFIFs.
A SIMPLIFIED ANALYTICAL MODEL FOR LAPLACIAN TRANSFER ACROSS DETERMINISTIC PREFRACTAL INTERFACES
Authors: GREBENKOV D. S. , FILOCHE M. , SAPOVAL B.
Published: April 2007

The role of the geometry of prefractal interfaces in Laplacian transport is analyzed through its "harmonic geometrical spectrum." This spectrum summarizes the properties of the Dirichlet-to-Neumann operator associated with these geometries. Numerical analysis shows that very few eigenmodes contribute significantly to the macroscopic response of the system. The hierarchical spatial frequencies of these particular modes correspond to the characteristic length scales of the interface. From this result, a simplified analytical model of the response of self-similar interfaces is developed. This model reproduces the classical low and high frequency asymptotic limits and gives an approximate constant phase angle behavior for the intermediate frequency region. It also provides an analytical description for the crossovers between these regimes and for their dependency on the order of the prefractal interface. In this frame, it is shown that the properties of any generation prefractal can be deduced from the properties of the fractal generator, which are easy to reach numerically.
DIMENSION THEORY OF LINEAR SOLENOIDS
Authors: NEUNHÄUSERER JÖRG
Published: April 2007

We develop the dimension theory for a class of linear solenoids, which have a "fractal" attractor. We will find the dimension of the attractor, proof formulas for the dimension of ergodic measures on this attractor and discuss the question of whether there exists a measure of full dimension.
HOMEOMORPHISM CLASSES OF SELF-CONTACTING SYMMETRIC BINARY FRACTAL TREES
Authors: TAYLOR TARA. D.
Published: April 2007

We fully describe the homeomorphism classes of self-contacting symmetric binary fractal trees, and provide the explicit homeomorphisms for the classes. In developing this theory, we introduce new notations, definitions and results regarding symmetric binary fractal trees. The set of tip points at maximal height for a class of trees forms a middle Cantor set. We study various aspects of the holes in self-contacting trees, and the hole locator pairs can be used to describe the homeomorphism classes.
Hypotonicity causes actin reorganization and recruitment of the actin-binding ERM protein moesin in membrane protrusions in collecting duct principal cells
Authors: Tamma Grazia , Procino Giuseppe , Svelto Maria , Valenti Giovanna
Published: April 2007

Hypotonicity-induced cell swelling is characterized by a modification in cell architecture associated with actin cytoskeleton remodeling. The ezrin/radixin/moesin (ERM) family proteins are important signal transducers during actin reorganization regulated by the monomeric G proteins of the Rho family. We report here that in collecting duct CD8 cells hypotonicity-induced cell swelling resulted in deep actin reorganization, consisting of loss of stress fibers and formation of F-actin patches in membrane protrusions where the ERM protein moesin was recruited. Cell swelling increased the interaction between actin and moesin and induced the transition of moesin from an oligomeric to a monomeric functional conformation, characterized by both the COOH- and NH2-terminal domains being exposed. In this conformation, which is stabilized by phosphorylation of a conserved threonine in the COOH-terminal domain by PKC or Rho kinase, moesin can bind interacting proteins. Interestingly, hypotonic stress increased the amount of threonine-phosphorylated moesin, which was prevented by the PKC-α inhibitor Gö-6976 (50 nM). In contrast, the Rho kinase inhibitor Y-27632 (1 μM) did not affect the hypotonicity-induced increase in phosphorylated moesin. The present data represent the first evidence that hypotonicity-induced actin remodeling is associated with phosphorylated moesin recruitment at the cell border and interaction with actin.
New functional aspects of the neuroendocrine marker secretagogin based on the characterization of its rat homolog
Authors: Gartner W. , Vila G. , Daneva T. , Nabokikh A. , Koc-Saral F. , Ilhan A. , Majdic O. , Luger A. , Wagner L.
Published: April 2007

Secretagogin is a recently cloned human β-cell-expressed EF-hand Ca2+-binding protein. Converging evidence indicates that it exerts Ca2+sensor activity and is involved in regulation of insulin synthesis and secretion. To obtain a potent tool for the extension of its functional analysis in rat in vitro systems, we cloned the rat homolog of human secretagogin. Using comparative sequence analysis, immunostaining, and immunoblotting, we demonstrated a high degree of sequence homology and similar tissue expression patterns of human and rat secretagogin. Highest rat secretagogin expression levels were found in pancreatic β-cells. On the basis of newly generated anti-rat secretagogin antibodies, we established a rat secretagogin-specific sandwich capture ELISA and demonstrated release of secretagogin from viable Rin-5F cells. Dexamethasone treatment of Rin-5F cells resulted in an increased secretagogin release rate, which was inversely correlated with insulin secretion. In contrast, the secretagogin transcription rate was markedly reduced. This resulted in a decreased intracellular secretagogin content under the influence of dexamethasone. Sucrose gradient cell fractionation analysis of Rin-5F cells confirmed the predominant cytosolic localization of secretagogin, with only limited association of secretagogin with insulin granules. The loss of intracellular secretagogin after dexamethasone treatment affected predominantly the insulin granule-associated secretagogin fractions. The sequence homology and the comparable tissue expression patterns of human and rat secretagogin indicate conserved intracellular functions. The effects of dexamethasone on the total secretagogin content in Rin-5F cells and on its intracellular distribution might result in an impaired Ca2+sensitivity of dexamethasone-treated insulin-secreting cells.
Physiological effects of nonthyroidal illness syndrome in patients after cardiac surgery
Authors: Spratt D. I. , Frohnauer M. , Cyr-Alves H. , Kramer R. S. , Lucas F. L. , Morton J. R. , Cox D. F. , Becker K. , Devlin J. T.
Published: April 2007

In a prospective randomized placebo-controlled study, we assessed potential physiological effects of nonthyroidal illness syndrome (NTIS) in acute illness. Coronary artery bypass graft surgery was employed as a prospective model of acute illness and NTIS. Triiodothyronine (T3) or placebo was infused for 24 h after surgery, with a T3dose selected to maintain postoperative serum T3concentrations at preoperative levels. Patients were evaluated before coronary artery bypass graft and during the postoperative period. Cardiovascular function was monitored with Swan-Ganz catheter measurements and ECG. Urinary nitrogen excretion and l-[1-13C]leucine flux were used to evaluate protein metabolism. Serum measurements of relevant hormones, iron, and total iron-binding capacity were used to assess effects on sex steroid, growth hormone axis, and iron responses to illness. Cardiovascular function was not affected by T3infusion, except for a transient higher cardiac index in the T3group 6 h after surgery (3.04 ± 0.12 for T3and 2.53 ± 0.08 for placebo, P = 0.0016). Protein metabolism was not affected; changes in urinary nitrogen excretion and l-[1-13C]leucine flux were equivalent in the two groups ( P = 0.35 and P = 0.95, respectively). No differences were observed in changes in testosterone, estrogens, growth hormone, insulin-like growth hormone I, iron, or total iron-binding capacity between T3and placebo groups. We conclude that, in the early stages of major illness, the decrease in circulating T3concentrations in NTIS has only a minimal transient physiological impact on cardiac function and plays no significant role in protecting against protein catabolism or modulating other endocrine responses or iron responses to illness.
Intermittent intraperitoneal infusion of peptide YY(3-36) reduces daily food intake and adiposity in obese rats
Authors: Chelikani Prasanth K. , Haver Alvin C. , Reidelberger Roger D.
Published: April 2007

Peptide YY(3-36) [PYY(3-36)] is a gut-brain peptide that decreases food intake when administered by intravenous infusion to lean and obese humans and rats. However, chronic administration of PYY(3-36) by osmotic minipump to lean and obese rodents produces only a transient reduction in daily food intake and weight gain. It has recently been shown that 1-h intravenous infusions of PYY(3-36) every other hour for 10 days produced a sustained reduction in daily food intake, body weight, and adiposity in lean rats. Here, we determined whether intermittent delivery of PYY(3-36) can produce a similar response in diet-induced obese rats. During a 21-day period, obese rats (body fat >25%) received twice daily intraperitoneal infusion of vehicle ( n = 18) or PYY(3-36) ( n = 24) during hours 1–3 and 7–9 of the dark period. Rats had free access to both a 45% fat solid diet and a 29% fat liquid diet; intakes were determined from continuous computer recording of changes in food container weights. To sustain a 15–25% reduction in daily caloric intake, the initial PYY(3-36) dose of 30 pmol·kg−1·min−1 was reduced to 10 pmol·kg−1·min−1 on day 10 and then increased to 17 pmol·kg−1·min−1 on day 13. This dosing strategy produced a sustained reduction in daily caloric intake of 11–32% and prevented body weight gain (8 ± 6 vs. 51 ± 11 g) and fat deposition (4.4 ± 7.6 vs. 41.0 ± 12.8 g). These results indicate that intermittent intraperitoneal infusion of PYY(3-36) can produce a sustained reduction in food intake and adiposity in diet-induced obese rodents consuming palatable high-fat foods.
Ontogeny of NHE8 in the rat proximal tubule
Authors: Becker Amy M. , Zhang Jianning , Goyal Sunita , Dwarakanath Vangipuram , Aronson Peter S. , Moe Orson W. , Baum Michel
Published: April 2007

Proximal tubule bicarbonate reabsorption is primarily mediated via the Na+/H+ exchanger, identified as NHE3 in adults. Previous studies have demonstrated a maturational increase in rat proximal tubule NHE3 expression, with a paucity of NHE3 expression in neonates, despite significant Na+-dependent proton secretion. Recently, a novel Na+/H+ antiporter (NHE8) was identified and found to be expressed on the apical membrane of the proximal tubule. To determine whether NHE8 may be the antiporter responsible for proton secretion in neonates, the present study characterized the developmental expression of NHE8 in rat proximal tubules. RNA blots and real-time RT-PCR demonstrated no developmental difference in the mRNA of renal NHE8. Immunoblots, however, demonstrated peak protein abundance of NHE8 in brush border membrane vesicles of 7- and 14-day-old compared with adult rats. In contrast, the level of NHE8 expression in total cortical membrane protein was higher in adults than in neonates. Immunohistochemistry confirmed the presence of NHE8 on the apical membrane of the proximal tubules of neonatal and adult rats. These data demonstrate that NHE8 does undergo maturational changes on the apical membrane of the rat proximal tubule and may account for the Na+-dependent proton flux in neonatal proximal tubules.
Object Category Structure in Response Patterns of Neuronal Population in Monkey Inferior Temporal Cortex
Authors: Kiani Roozbeh , Esteky Hossein , Mirpour Koorosh , Tanaka Keiji
Published: April 2007

Our mental representation of object categories is hierarchically organized, and our rapid and seemingly effortless categorization ability is crucial for our daily behavior. Here, we examine responses of a large number (>600) of neurons in monkey inferior temporal (IT) cortex with a large number (>1,000) of natural and artificial object images. During the recordings, the monkeys performed a passive fixation task. We found that the categorical structure of objects is represented by the pattern of activity distributed over the cell population. Animate and inanimate objects created distinguishable clusters in the population code. The global category of animate objects was divided into bodies, hands, and faces. Faces were divided into primate and nonprimate faces, and the primate-face group was divided into human and monkey faces. Bodies of human, birds, and four-limb animals clustered together, whereas lower animals such as fish, reptile, and insects made another cluster. Thus the cluster analysis showed that IT population responses reconstruct a large part of our intuitive category structure, including the global division into animate and inanimate objects, and further hierarchical subdivisions of animate objects. The representation of categories was distributed in several respects, e.g., the similarity of response patterns to stimuli within a category was maintained by both the cells that maximally responded to the category and the cells that responded weakly to the category. These results advance our understanding of the nature of the IT neural code, suggesting an inherently categorical representation that comprises a range of categories including the amply investigated face category.
Mapping Function Onto Neuronal Morphology
Authors: Stiefel Klaus M. , Sejnowski Terrence J.
Published: April 2007

Neurons have a wide range of dendritic morphologies the functions of which are largely unknown. We used an optimization procedure to find neuronal morphological structures for two computational tasks: first, neuronal morphologies were selected for linearly summing excitatory synaptic potentials (EPSPs); second, structures were selected that distinguished the temporal order of EPSPs. The solutions resembled the morphology of real neurons. In particular the neurons optimized for linear summation electrotonically separated their synapses, as found in avian nucleus laminaris neurons, and neurons optimized for spike-order detection had primary dendrites of significantly different diameter, as found in the basal and apical dendrites of cortical pyramidal neurons. This similarity makes an experimentally testable prediction of our theoretical approach, which is that pyramidal neurons can act as spike-order detectors for basal and apical inputs. The automated mapping between neuronal function and structure introduced here could allow a large catalog of computational functions to be built indexed by morphological structure.
Characterization of Voltage-Gated Ionic Channels in Cholinergic Amacrine Cells in the Mouse Retina
Authors: Kaneda Makoto , Ito Koichi , Morishima Yosuke , Shigematsu Yasuhide , Shimoda Yukio
Published: April 2007

Recent studies have shown that cholinergic amacrine cells possess unique membrane properties. However, voltage-gated ionic channels in cholinergic amacrine cells have not been characterized systematically. In this study, using electrophysiological and immunohistochemical techniques, we examined voltage-gated ionic channels in a transgenic mouse line the cholinergic amacrine cells of which were selectively labeled with green fluorescent protein (GFP). Voltage-gated K+ currents contained a 4-aminopyridine-sensitive current (A current) and a tetraethylammonium-sensitive current (delayed rectifier K+ current). Voltage-gated Ca2+ currents contained a ω-conotoxin GVIA-sensitive component (N-type) and a ω-Aga IVA-sensitive component (P/Q-type). Tetrodotoxin-sensitive Na+ currents and dihydropyridine-sensitive Ca2+ currents (L-type) were not observed. Immunoreactivity for the Na channel subunit (Pan Nav), the K channel subunits (the A-current subunits [Kv. 3.3 and Kv 3.4]) and the Ca channel subunits (α1A [P/Q-type], α1B [N-type] and α1C [L-type]) was detected in the membrane fraction of the mouse retina by Western blot analysis. Immunoreactivity for the Kv. 3.3, Kv 3.4, α1A [P/Q-type], and α1B [N-type] was colocalized with the GFP signals. Immunoreactivity for α1C [L-type] was not colocalized with the GFP signals. Immunoreactivity for Pan Nav did not exist on the membrane surface of the GFP-positive cells. Our findings indicate that signal propagation in cholinergic amacrine cells is mediated by a combination of two types of voltage-gated K+ currents (the A current and the delayed rectifier K+ current) and two types of voltage-gated Ca2+ currents (the P/Q-type and the N-type) in the mouse retina.
Collateral density, remodeling, and VEGF-A expression differ widely between mouse strains
Authors: Chalothorn Dan , Clayton Jason A. , Zhang Hua , Pomp Daniel , Faber James E.
Published: April 2007

Substantial variability exists in collateral density and ischemia-induced collateral growth among species. To begin to probe the underlying mechanisms, which are unknown, we characterized two mouse strains with marked differences in both parameters. Immediately after femoral artery ligation, collateral and foot perfusion were lower in BALB/c than C57BL/6 ( P < 0.05 here and below), suggesting fewer pre-existing collaterals. This was confirmed with angiography and immunohistochemistry (∼35% fewer collaterals in the BALB/c's thigh). Recovery of hindlimb perfusion was attenuated in BALB/c, in association with 54% less collateral remodeling, reduced angiogenesis, greater ischemia, and more impaired hindlimb use. Densities of CD45+and CD4+leukocytes around collaterals increased similarly, but TNF-α expression was 50% lower in BALB/c, which may contribute to reduced collateral remodeling. In normal tissues, compared with C57BL/6, BALB/c exhibit an altered arterial branching pattern and, like skeletal muscle above, have 30% fewer collaterals in intestine and, remarkably, almost none in pial circulation, resulting in greatly impaired perfusion after cerebral artery occlusion. Ischemic induction of VEGF-A was attenuated in BALB/c. Analysis of a C57BL/6 × BALB/c recombinant inbred strain dataset identified a quantitative trait locus for VEGF-A mRNA abundance at or near the Vegfa locus that associates with lower expression in BALB/c. This suggests a cis-acting polymorphism in the Vegfa gene in BALB/c could contribute to reduced VEGF-A expression and, in turn, the above deficiencies in this strain. These findings suggest these strains offer a model to investigate genetic determinants of collateral formation and growth in ischemia.
Disordered Lipid Metabolism and the Pathogenesis of Insulin Resistance
Authors: Savage David B. , Petersen Kitt Falk , Shulman Gerald I.
Published: April 2007

Although abnormal glucose metabolism defines type 2 diabetes mellitus (T2DM) and accounts for many of its symptoms and complications, efforts to understand the pathogenesis of T2DM are increasingly focused on disordered lipid metabolism. Here we review recent human studies exploring the mechanistic links between disorders of fatty acid/lipid metabolism and insulin resistance. As “mouse models of insulin resistance” were comprehensively reviewed in Physiological Reviews by Nandi et al. in 2004, we will concentrate on human studies involving the use of isotopes and/or magnetic resonance spectroscopy, occasionally drawing on mouse models which provide additional mechanistic insight.
The Angiotensin II AT1Receptor Structure-Activity Correlations in the Light of Rhodopsin Structure
Authors: Oliveira Laerte , Costa-Neto Claudio M. , Nakaie Clovis R. , Schreier Shirley , Shimuta Suma I. , Paiva Antonio C. M.
Published: April 2007

The most prevalent physiological effects of ANG II, the main product of the renin-angiotensin system, are mediated by the AT1receptor, a rhodopsin-like AGPCR. Numerous studies of the cardiovascular effects of synthetic peptide analogs allowed a detailed mapping of ANG II's structural requirements for receptor binding and activation, which were complemented by site-directed mutagenesis studies on the AT1receptor to investigate the role of its structure in ligand binding, signal transduction, phosphorylation, binding to arrestins, internalization, desensitization, tachyphylaxis, and other properties. The knowledge of the high-resolution structure of rhodopsin allowed homology modeling of the AT1receptor. The models thus built and mutagenesis data indicate that physiological (agonist binding) or constitutive (mutated receptor) activation may involve different degrees of expansion of the receptor's central cavity. Residues in ANG II structure seem to control these conformational changes and to dictate the type of cytosolic event elicited during the activation. 1) Agonist aromatic residues (Phe8and Tyr4) favor the coupling to G protein, and 2) absence of these residues can favor a mechanism leading directly to receptor internalization via phosphorylation by specific kinases of the receptor's COOH-terminal Ser and Thr residues, arrestin binding, and clathrin-dependent coated-pit vesicles. On the other hand, the NH2-terminal residues of the agonists ANG II and [Sar1]-ANG II were found to bind by two distinct modes to the AT1receptor extracellular site flanked by the COOH-terminal segments of the EC-3 loop and the NH2-terminal domain. Since the [Sar1]-ligand is the most potent molecule to trigger tachyphylaxis in AT1receptors, it was suggested that its corresponding binding mode might be associated with this special condition of receptors.
Physiology and Pathophysiology of Purinergic Neurotransmission
Authors: Burnstock Geoffrey
Published: April 2007

This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
Understanding the Complexity of
Trans
Fatty Acid Reduction in the American Diet
Authors: Eckel Robert H. , Borra Susan , Lichtenstein Alice H. , Yin-Piazza Shirley Y.
Published: April 2007

A 2-day forum was convened to discuss the current status and future implications of reducing
trans
fatty acids without increasing saturated fats in the food supply while maintaining functionality and consumer acceptance of packaged, processed, and prepared foods. Attendees represented the agriculture and oilseed industry and oil processing, food manufacturing, food service, government, food technology, and health and nutrition disciplines. Presentations included food science behind fatty acid technology, the health science of dietary fatty acids, alternatives to
trans
fatty acids, and the use of alternatives in food manufacturing and food service. The reduction of
trans
fatty acids in the food supply is a complex issue involving interdependent and interrelated stakeholders. Actions to reduce
trans
fatty acids need to carefully consider both intended and unintended consequences related to nutrition and public health. The unintended consequence of greatest concern is that fats and oils high in saturated fats, instead of the healthier unsaturated fats, might be used to replace fats and oils with
trans
fatty acids. Many different options of alternative oils and fats to replace
trans
fatty acids are available or in development. Decisions on the use of these alternatives need to consider availability, health effects, research and development investments, reformulated food quality and taste, supply-chain management, operational modifications, consumer acceptance, and cost. The conference demonstrated the value of collaboration between the food industry and health and nutrition professionals, and this conference model should be used to address other food development, processing, and/or technology issues.
Generative Systems and the Cinematic Spaces of Film and Installation Art
Authors: Leggett Mike
Published: April 2007

The author's informal research in the 1970s explored iterative and generative systems using motion-picture film. His approach was practice-based and occurred in the context of artists studying the structure and materiality of the film experience. Based on historical and contemporary notes he accumulated about his film Red+Green+Blue, the author evaluates the generative art that emerged using this analogue-based medium in the light of recent discussion of digital and binary-based interactive installations.
Electronic Music for Bio-Molecules Using Short Music Phrases
Authors: Shi X.J. , Cai Y.Y. , Chan C.W.
Published: April 2007

The authors explore protein sonification issues using Morse code theory. Short musical phrases based on protein amino acids are used to compose protein music. Rhythms and tunes familiar to teenagers are also investigated, with the aim of producing different genres of protein music. A special musical instrument, the Chinese guzheng, can be employed to play the protein music. Experiment is carried out with different proteins, including the HIV main protease. It is hoped that this study can help unveil the mysteries of nature and motivate students to learn biology.
Emerging Congruence between Animation and Anatomy
Authors: O'Neill Rob
Published: April 2007

The worlds of animation and anatomy have a long-standing connection based on both direct and indirect collaboration. The author surveys a number of projects in which anatomists have consulted on animation projects or animation techniques have been used for data gathering and analysis. The author describes his own work in light of this connection.
A Reclusive Artist Meets Minds with a World-Famous Geometer: George Odom and H.S.M. (Donald) Coxeter
Authors: Roberts Siobhan
Published: April 2007

The author discusses the wide-ranging correspondence of renowned geometer H.S.M. (Donald) Coxeter with George Odom, an artist who has made several geometric discoveries while living in seclusion. Coxeter was responsible for bringing these insights to wider attention
The Media Art Notation System: Documenting and Preserving Digital/Media Art
Authors: Rinehart Richard
Published: April 2007

This paper proposes a new approach to conceptualizing digital and media art forms. This theoretical approach will be explored through issues raised in the process of creating a formal declarative model (alternately known as a metadata framework, notation system or ontology) for digital and media art. The approach presented and explored here is intended to inform a better understanding of media art forms and to provide a practical descriptive framework that supports their creation, re-creation, documentation and preservation.
The Cybernetic Stance: My Process and Purpose
Authors: Ascott Roy
Published: April 2007

There is apparently a paradox in that, as artists, some of us become progressively process-oriented, but continue to produce art objects. For me this is necessary since I work on two levels from a common set of attitudes: on the social level, elaborating plans for a Cybernetic Art Matrix; on the intimate level making individual art works. Both processes are concerned with creating triggers—initiating creative behaviour in the observer/participant. Modern art is characterized by a behaviourist tendency in which process and system are cardinal factors. As distinctions between music, painting, poetry, etc. become blurred and media are mixed, a bahaviourist synthesis is seen to evolve, in which dialogue and feedback within a social culture indicate the emergence of a Cybernetic vision in art as in science.

My artifacts come out of a process of random behaviour interacting with pre-established conditions. The Cybernetic Art Matrix is seen as a process in which anarchic group behaviour interacts with pre-established systems of communications, hardware and learning nets. In both cases the processes are self-generating and self-critical. Basically they are initiated by creative behaviour, and in turn give rise to its extension in other people.
When Unwed Mothers Marry
Authors: Deborah Roempke Graefe  , Lichter Daniel T.
Published: April 2007

The promotion of marriage and two-parent families as a strategy to reduce welfare dependency continues to be a major public policy goal of the 1996 welfare reform. Based on the assumption that women will marry employed men and that their earnings will lift poor mothers and their children from public dependency, this objective raises important policy questions. In this article, the authors investigate the extent to which unwed mothers—a large proportion of all welfare mothers—enter into and maintain stable cohabiting and marital relationships with economically attractive men. Using retrospective data on relationship histories for 3,872 women from the 1995 National Survey of Family Growth, the authors examine the marital life course of unwed mothers and document the social and economic characteristics of their partners at midlife. Their marital search model shows that nonmarital childbearing is adversely associated with the ability to marry economically attractive men and maintain long-term marital unions.
Disaggregating the Effects of Marital Trajectories on Health
Authors: Dupre Matthew E. , Meadows Sarah O.
Published: April 2007

Recent studies linking marital status and health increasingly focus on marital trajectories to examine the relationship from a life course perspective. However, research has been slow to bridge the theoretical concept of a marital trajectory with its measurement. This study uses retrospective and prospective data to model the age-dependent effects of marital sequences, timing, transitions, and durations on physical health. Results indicate that marriage duration is associated with lower rates of disease for men and women; however, the effect is time dependent and contingent on other trajectory components. For females, marriage timing and the cumulative number of divorce transitions are also important for health. For males, divorce duration and widowhood transitions play an integral role in this process. The authors also find that marital typologies have no effect when the number of transitions is taken into account.
Latent Profiles Among Sexual Assault Survivors
Authors: Macy Rebecca J. , Nurius Paula S. , Norris Jeanette
Published: April 2007

Little guidance exists about how to tailor empowerment and resistance sexual assault programming to be responsive to varying groups of women. Using an investigation of 415 college women who completed a self-administered survey about a range of sexually aggressive experiences by a known male assailant, this investigation tested for distinct multivariate profiles of contextual factors among sexually assaulted women to discern how these factors may differentially combine to influence women's vulnerability to sexual assault. We applied latent profile analysis (LPA) to determine meaningful subgroups of women based on interrelationships among factors that contextualize women's vulnerability to sexual assault, including prior victimization, alcohol consumption, relationship expectancies of the assailant, and assertive precautionary habits. LPA established four significantly distinct multivariate profiles of substantively different groups of women. Group difference tests reinforced the findings and aided in group profile interpretations. Implications for the development of tailored resistance and empowerment programs are discussed.
The Decertification of Transferred Youth
Authors: Jordan Kareem L. , Myers David L.
Published: April 2007

Much of the research on juvenile transfer to adult court examines the predictors of the waiver decision. Few studies, however, have focused on the determinants of decertification, a process whereby certain initially transferred youth are reverse waived to juvenile court. This study sought to examine this underresearched area by focusing specifically on the factors that predict decertification and utilizing quantitative data pertaining to 345 youth initially transferred to adult court in 1996 under Pennsylvania's law that automatically excludes certain youth from juvenile court jurisdiction. The findings indicated that legal factors are the strongest predictors of decertification. The need for further research and policy implications also are discussed.
Constitutive phosphoinositide 3-kinase/Akt activation represents a favorable prognostic factor in de novo acute myelogenous leukemia patients
Authors: Tamburini Jerome , Elie Caroline , Bardet Valérie , Chapuis Nicolas , Park Sophie , Broët Philippe , Cornillet-Lefebvre Pascale , Lioure Bruno , Ugo Valérie , Blanchet Odile , Ifrah Norbert , Witz Francis , Dreyfus François , Mayeux Patrick , Lacombe Catherine , Bouscary Didier
Published: April 2007

The phosphoinositide 3-kinase (PI3K/Akt) pathway is activated in acute myelogenous leukemia (AML) and is promising for targeted inhibition. Ninety-two patients with primary AML were analyzed for PI3K/Akt constitutive activation. Fifty percent of the patients presented with constitutive PI3K activation (PI3K +). No difference was observed between PI3K + and PI3K − groups concerning age, sex, white blood cell count, lactate dehydrogenase (LDH) level, bone marrow blast cells, French-American-British (FAB) classification, cytogenetics, RAS or nucleophosmin (NPM) mutations. Slightly more FLT3-ITD was detected in the PI3K − group (P = .048). The complete remission rate was similar between the 2 groups. With a median follow-up of 26 months, we observed for PI3K + and PI3K − patients, respectively, 56% and 33% overall survival (P = .001) and 72% and 41% relapse-free survival (P = .001). Constitutive PI3K/Akt activity is a favorable prognosis factor in AML, even after adjustment for FLT3-ITD, and may confer a particular sensitivity to chemotherapy. A better understanding of the downstream effectors of the PI3K/Akt pathway is needed before targeting in AML.
Regulation of COX-2–mediated signaling by α3 type IV noncollagenous domain in tumor angiogenesis
Authors: Boosani Chandra Shekhar , Mannam Arjuna P. , Cosgrove Dominic , Silva Rita , Hodivala-Dilke Kairbaan M. , Keshamouni Venkateshwar G. , Sudhakar Akulapalli
Published: April 2007

Human α3 chain, a noncollagenous domain of type IV collagen [α3(IV)NC1], inhibits angiogenesis and tumor growth. These biologic functions are partly attributed to the binding of α3(IV)NC1 to αVβ3 and α3β1 integrins. α3(IV)NC1 binds αVβ3 integrin, leading to translation inhibition by inhibiting focal adhesion kinase/phosphatidylinositol 3-kinase/Akt/mTOR/4E-BP1 pathways. In the present study, we evaluated the role of α3β1 and αVβ3 integrins in tube formation and regulation of cyclooxygenase-2 (COX-2) on α3(IV)NC1 stimulation. We found that although both integrins were required for the inhibition of tube formation by α3(IV)NC1 in endothelial cells, only α3β1 integrin was sufficient to regulate COX-2 in hypoxic endothelial cells. We show that binding of α3(IV)NC1 to α3β1 integrin leads to inhibition of COX-2–mediated pro-angiogenic factors, vascular endothelial growth factor, and basic fibroblast growth factor by regulating IκBα/NFκB axis, and is independent of αVβ3 integrin. Furthermore, β3 integrin–null endothelial cells, when treated with α3(IV)NC1, inhibited hypoxia-mediated COX-2 expression, whereas COX-2 inhibition was not observed in α3 integrin–null endothelial cells, indicating that regulation of COX-2 by α3(IV)NC1 is mediated by integrin α3β1. Our in vitro and in vivo findings demonstrate that α3β1 integrin is critical for α3(IV)NC1-mediated inhibition of COX-2–dependent angiogenic signaling and inhibition of tumor progression.
Increased risk of pregnancy complications in patients with essential thrombocythemia carrying the JAK2 (617V>F) mutation
Authors: Passamonti Francesco , Randi Maria Luigia , Rumi Elisa , Pungolino Ester , Elena Chiara , Pietra Daniela , Scapin Margherita , Arcaini Luca , Tezza Fabiana , Moratti Remigio , Pascutto Cristiana , Fabris Fabrizio , Morra Enrica , Cazzola Mario , Lazzarino Mario
Published: April 2007

Essential thrombocythemia (ET) may occur in women of childbearing age. To investigate the risk of pregnancy complications, we studied 103 pregnancies that occurred in 62 women with ET. The 2-tailed Fisher exact test showed that pregnancy outcome was independent from that of a previous pregnancy. The rate of live birth was 64%, and 51% of pregnancies were uneventful. Maternal complications occurred in 9%, while fetal complications occurred in 40% of pregnancies. The Mantel-Haenszel method showed that fetal loss in women with ET was 3.4-fold higher (95% confidence interval [CI]: 3-3.9; P < .001) than in the general population. Half of the women studied carried the JAK2 (617V>F) mutation, and a multivariate logistic regression model identified this mutation as an independent predictor of pregnancy complications (P = .01). Neither the platelet count nor the leukocyte count was a risk factor. JAK2 (617V>F)–positive patients had an odds ratio of 2.02 (95% CI: 1.1 - 3.8) of developing complications in comparison with JAK2 (617V>F)–negative patients. Aspirin did not prevent complication in JAK2 (617V>F)–positive patients and appeared to worsen outcome in JAK2 (617V>F)–negative patients. A relationship was found between JAK2 (617V>F) and fetal loss (P = .05). This study indicates that patients carrying the JAK2 (617V>F) mutation have higher risk of developing pregnancy complications.