bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Pair Dispersion in Turbulent Flow
Authors: Bourgoin Mickaël , Ouellette Nicholas T. , Xu Haitao , Berg Jacob , Bodenschatz Eberhard
Published: February 2006

Mixing and transport in turbulent flows—which have strong local concentration fluctuations—are essential in many natural and industrial systems including reactions in chemical mixers, combustion in engines and burners, droplet formation in warm clouds, and biological odor detection and chemotaxis. Local concentration fluctuations, in turn, are intimately tied to the problem of the separation of pairs of fluid elements. We have measured this separation rate in an intensely turbulent laboratory flow and have found, in quantitative agreement with the seminal predictions of Batchelor, that the initial separation of the pair plays an important role in the subsequent spreading of the fluid elements. These results have surprising consequences for the decay of concentration fluctuations and have applications to biological and chemical systems.
Translational Regulators Maintain Totipotency in the
Caenorhabditis elegans
Germline
Authors: Ciosk Rafal , DePalma Michael , Priess James R.
Published: February 2006

The molecular mechanisms that maintain totipotency of the germline are not well understood. Here, we show that two conserved translational regulators, MEX-3 and GLD-1, are essential for maintaining totipotency in the
Caenorhabditis elegans
germline. In
mex-3 gld-1
mutants, germ cells transdifferentiate into various somatic cell types such as muscles or neurons. Our findings implicate RNA regulation in the maintenance of totipotency, suggest that multiple mechanisms maintain totipotency at different stages of germline development, and establish a genetically tractable model for studying the development of teratomas.
Histone H4-K16 Acetylation Controls Chromatin Structure and Protein Interactions
Authors: Shogren-Knaak Michael , Ishii Haruhiko , Sun Jian-Min , Pazin Michael J. , Davie James R. , Peterson Craig L.
Published: February 2006

Acetylation of histone H4 on lysine 16 (H4-K16Ac) is a prevalent and reversible posttranslational chromatin modification in eukaryotes. To characterize the structural and functional role of this mark, we used a native chemical ligation strategy to generate histone H4 that was homogeneously acetylated at K16. The incorporation of this modified histone into nucleosomal arrays inhibits the formation of compact 30-nanometer–like fibers and impedes the ability of chromatin to form cross-fiber interactions. H4-K16Ac also inhibits the ability of the adenosine triphosphate–utilizing chromatin assembly and remodeling enzyme ACF to mobilize a mononucleosome, indicating that this single histone modification modulates both higher order chromatin structure and functional interactions between a nonhistone protein and the chromatin fiber.
The Heterologous Siderophores Ferrioxamine B and Ferrichrome Activate Signaling Pathways inPseudomonas aeruginosa
Authors: Llamas María A. , Sparrius Marion , Kloet Roy , Jiménez Connie R. , Vandenbroucke-Grauls Christina , Bitter Wilbert
Published: February 2006

Pseudomonas aeruginosasecretes two siderophores, pyoverdine and pyochelin, under iron-limiting conditions. These siderophores are recognized at the cell surface by specific outer membrane receptors, also known as TonB-dependent receptors. In addition, this bacterium is also able to incorporate many heterologous siderophores of bacterial or fungal origin, which is reflected by the presence of 32 additional genes encoding putative TonB-dependent receptors. In this work, we have used a proteomic approach to identify the inducing conditions forP. aeruginosaTonB-dependent receptors. In total, 11 of these receptors could be discerned under various conditions. Two of them are only produced in the presence of the hydroxamate siderophores ferrioxamine B and ferrichrome. Regulation of their synthesis is affected by both iron and the presence of a cognate siderophore. Analysis of theP. aeruginosagenome showed that both receptor genes are located next to a regulatory locus encoding an extracytoplasmic function sigma factor and a transmembrane sensor. The involvement of this putative regulatory locus in the specific induction of the ferrioxamine B and ferrichrome receptors has been demonstrated. These results show thatP. aeruginosahas evolved multiple specific regulatory systems to allow the regulation of TonB-dependent receptors.
AN UNIVERSALITY RESULT FOR A (MEM)BRANE CALCULUS BASED ON MATE/DRIP OPERATIONS
Authors: CARDELLI LUCA , PĂUN GHEORGHE
Published: February 2006

Operations with membranes are essential both in brane calculi and in membrane computing. In this paper we take four basic operations from brane calculi, pino, exo, mate, drip, we express them in terms of the membrane computing formalism, and then we investigate the computing power of the P systems using the mate, drip operations as unique evolution rules. All operations are controlled by – and make evolve – multisets of protein-objects embedded in the membranes themselves (not contained in the compartments of the cell, as standard in membrane computing; all compartments delimited by membranes are here empty). Somewhat surprisingly, for systems which use the mate, drip operations we obtain the Turing completeness. The power of P systems based on other operations remains to be investigated.
ON SIMULATING A CLASS OF PARALLEL ARCHITECTURES
Authors: CETERCHI RODICA , PÉREZ-JIMÉNEZ MARIO J.
Published: February 2006

The purpose of this paper is twofold. On one hand, we introduce the concept of P system with dynamic communication graphs in its full generality, independent of applications. On the other hand, we illustrate one application of it to the simulation of a class of parallel architectures. In this last direction we extend previous work concerned with the simulation of particular architectures.
COMPLEXITY OF BIO-COMPUTATION: SYMBOLIC DYNAMICS IN MEMBRANE SYSTEMS
Authors: MUSKULUS MICHAEL , BRIJDER ROBERT
Published: February 2006

We discuss aspects of biological relevance to the modelling of bio-computation in a multiset rewriting system context: turnover, robustness against perturbations, and the dataflow programming paradigm. The systems under consideration are maximally parallel and asynchronous parallel membrane systems, the latter corresponding to computation in which the notion of time is operationally meaningless.

A natural geometrical setting which seems promising for the study of computational processes in general multiset rewriting systems is presented. Configuration space corresponds to a subset of the lattice [Formula: see text], d ∈ N, and state transitions correspond to vector addition. The similarities and differences with Vector Addition Systems and Petri nets are discussed. Symbolic dynamics are introduced on special partitions of configuration space and we indicate different notions of complexity for membrane systems based on this and related concepts such as graph complexity and minimal automata. Some examples of synchronized, pipelined dataflow computations are given and decompositions into functional subunits are briefly commented on.
FURTHER RESULTS ON P SYSTEMS WITH PROMOTERS/INHIBITORS
Authors: SBURLAN DRAGOŞ
Published: February 2006

This paper presents several results regarding P systems with non-cooperative rules and promoters/inhibitors at the level of rules. For the class of P systems using inhibitors, generating families of sets of vectors of numbers, a characterization of the family of Parikh sets of ET0L languages is shown. In the case of P systems with non-cooperative promoted rules even if an upper bound was not given, the inclusion of the family PsET0L was proved. Moreover, a characterization of such systems by means of a particular form of random context grammars, therefore a sequential formal device, is proposed.
COMPLETENESS AND REALIZABILITY: CONDITIONS FOR AUTOMATIC GENERATION OF WORKFLOWS
Authors: LU SHIYONG , BERNSTEIN ARTHUR J. , LEWIS PHILIP M.
Published: February 2006

In recent years, workflow technology has greatly facilitated business process modeling and reengineering in information systems. On one hand, the separation of an application's control structure from the implementation of its task programs simplifies and speeds up application development. On the other hand, the run-time system assists users in coordinating and scheduling tasks of a business process. As a result, the cost of doing business is reduced, and business enterprises become more responsive to new business requirements and opportunities, hence, become more competitive in the market. Several formal methods have been proposed for specifying and modeling workflows. However, most workflows are designed manually, which becomes a time-consuming and error-prone procedure when a workflow involves hundreds or thousands of task programs. A recent approach is to generate workflow automatically from a task library and a specification of the desired outcome. In this paper, we define the notions of positive and negative dependency graphs for a task library to represent the dependencies among tasks in the library. Based on these dependencies, we identified sufficient conditions for a task library to be complete, and the conditions for a workflow postcondition to be realizable from a task library. We also identified a sufficient and necessary condition for the completeness of a class of task libraries, called S-task libraries.
CURVATURE AND INTEGRABILITY OF AN ALMOST HERMITIAN STRUCTURE
Authors: TANG ZIZHOU
Published: February 2006

By using moving frame theory, we obtain some necessary conditions involving curvatures for integrability of an almost Hermitian structure. As consequences, they are applied to S6.
ON THE INDUCTIVE LIMIT STRUCTURE OF ORDER FOUR AUTOMORPHISMS OF THE IRRATIONAL ROTATION ALGEBRA
Authors: WALTERS S.
Published: February 2006

It is shown that there exists an order four automorphism of the irrational rotation algebra Aθ that leaves invariant an increasing sequence of unital C*-subalgebras consisting of two circles and two points and such that its induced map on K1(Aθ) is given by the matrix [Formula: see text]. The resulting fixed point algebra is shown to be approximately finite-dimensional. A brief survey of recent work on the canonical finite order automorphisms of Aθ is given and some open problems are posed.
ON THE LOGARITHMIC KODAIRA DIMENSION OF AFFINE THREEFOLDS
Authors: KISHIMOTO TAKASHI
Published: February 2006

In this article, we shall consider how to analyze affine threefolds associated to the log Kodaira dimension [Formula: see text] and make the framework for this purpose under a certain geometric condition. As a consequence of our main result, under this geometric condition, we can describe the construction of affine threefolds with [Formula: see text] fairly explicitly, and show that affine threefolds with [Formula: see text] have the structure of ℂ*-fibrations.
A STABILIZING SUBGRID FOR CONVECTION–DIFFUSION PROBLEM
Authors: NESLITURK ALI I.
Published: February 2006

A stabilizing subgrid which consists of a single additional node in each triangular element is analyzed by solving the convection–diffusion problem, especially in the case of small diffusion. The choice of the location of the subgrid node is based on minimizing the residual of a local problem inside each element. We study convergence properties of the method under consideration and its connection with previously suggested stabilizing subgrids. We prove that the standard Galerkin finite element solution on augmented grid produces a discrete solution that satisfy the same a priori error estimates that are typically obtained with SUPG and RFB methods. Some numerical experiments that confirm the theoretical findings are also presented.
EDGE ELEMENT COMPUTATION OF MAXWELL'S EIGENVALUES ON GENERAL QUADRILATERAL MESHES
Authors: BOFFI DANIELE , KIKUCHI FUMIO , SCHÖBERL JOACHIM
Published: February 2006

Recent results prove that Nédélec edge elements do not achieve optimal rate of approximation on general quadrilateral meshes. In particular, lowest order edge elements provide stable but non-convergent approximation of Maxwell's eigenvalues. In this paper we analyze a modification of standard edge element that restores the optimality of the convergence. This modification is based on a projection technique that can be interpreted as a reduced integration procedure.
CONVERGENCE OF A FINITE ELEMENT DISCRETIZATION FOR THE LANDAU–LIFSHITZ EQUATIONS IN MICROMAGNETISM
Authors: ALOUGES FRANÇOIS , JAISSON PASCAL
Published: February 2006

In this paper we propose a new space and time finite elements discretization of the Landau–Lifshitz equations which may be readily used for numerical computations. We then prove its convergence to a weak solution in the sense given by Alouges and Soyeur or Labbé in the literature.
FACIAL EXPRESSION RECOGNITION BASED ON GABOR WAVELET TRANSFORMATION AND ELASTIC TEMPLATES MATCHING
Authors: ZHAN YONGZHAO , YE JINGFU , NIU DEJIAO , CAO PENG
Published: February 2006

Facial expression recognition technology plays an important role in research areas such as psychological studies, image understanding and virtual reality etc. In order to achieve subject-independent facial expression recognition and obtain robustness against illumination variety and image deformation, facial expression recognition methods based on Gabor wavelet transformation and elastic templates matching are presented in this paper. First given a still image containing facial expression information, preprocessors are executed which include gray and scale normalization. Secondly, Gabor wavelet filters are adopted to extract expression features. Then the elastic graph for expression features is constructed. Finally, elastic templates matching algorithm and K-nearest neighbors classifier are used to recognize facial expression. Experiments show that expression features can be extracted effectively by Gabor wavelet transformation, which is insensitive to illumination variety and individual difference, and high recognition rate can be obtained using elastic templates matching algorithm, which is subject-independent.
ARTISTIC MOSAIC SERIES GENERATION
Authors: LI XUELONG , YUAN YUAN , TAO DACHENG
Published: February 2006

Human tastes in art motivate the need for effective means to build a visual mosaic picture which is made up of many small tiles. In some previous work researchers have tried to translate pictures' styles.1 In this paper, a new approach to image processing in arts is presented in the domain of generating a series of artistic mosaic pictures. An arbitrary image is first translated into a mosaic-based one by dividing it into a number of sub-blocks each with the mean value of the pixels in it. Each of these small fragments can be assigned a new location within this image so that a new mosaic picture is generated. By this mean, images with similar color features can be used to create a series of mosaic pictures. The mosaic pictures consist of the same elements as each other, but might be extremely different from the semantic contents. A basic algorithm is presented, followed by some further improvements. Some preliminary experimental results are then given to show the impact of the proposed special techniques.
DESIGN REVIEW IN A DISTRIBUTED COLLABORATIVE VIRTUAL ENVIRONMENT
Authors: CAO WEIQUN , GAERTNER HENDRIK , GUDDAT HANNES , STRAUBE ANDREAS M. , CONRAD STEFAN , KRUIJFF ERNST , LANGENBERG DIRK
Published: February 2006

Virtual Reality leads Digital Product Development technology to a more effective and convenient way by presenting the product model in an immersive real 3D environment. Distributed VR even enables partners to discuss the design of the product independent of their locations. This paper introduces our work with a Digital Product Development System with Virtually Cooperating Teams Using High Bandwidth Networks — ProViT, which aims at building up immersive telepresence systems for design review across high-bandwidth networks. Video and audio streaming are integrated in the virtual environment to support immersive teleconference aspects of the distributed design review sessions. A network management system has been developed for the supervision, maintenance and processing of distributed setups, and network security.
FLOW DRIVEN ELECTRONIC TRANSPORT IN CARBON NANOTUBES
Authors: SOOD A. K. , GHOSH SHANKAR , KUMAR N.
Published: February 2006

The flow of a liquid on single-walled carbon nanotube bundles induces an electrical signal (voltage/current) in the sample along the direction of the flow. The electrical response is found to be logarithmic in the flow speed over a wide range. The magnitude of the flow induced electrical signal generated depends sensitively on the ionic conductivity and the polar nature of the liquid, and electrical biasing of the nanotubes can control its direction. Our measurements suggest that the dominant mechanism responsible for this highly sub-linear response should involve a direct forcing of the free charge carriers in the nanotubes by the fluctuating Coulombic field of the liquid flowing past it.
NANOMEDICINES: DELIVERING DRUGS USING BOTTOM UP NANOTECHNOLOGY
Authors: GARNETT MARTIN
Published: February 2006

The use of nanosized materials changes the way in which drugs are handled by the body and offers opportunities to improve drug delivery. The physiological mechanisms controlling the distribution of nanosized materials (enhanced permeability and retention effect, cellular uptake pathways and opsonisation/elimination of nanoparticles) are described. Two different nanosized drug delivery systems are considered; drug delivery and DNA delivery. The deficiencies of currently available biodegradable polymers for preparation of drug containing nanoparticles are mainly the amount of drug that can be incorporated and the rapid rate of drug release. The development of new biodegradable polymers which can interact with the drug and so significantly increase drug loading and decrease the rate of drug release are outlined. DNA delivery necessitates overcoming a variety of biological barriers. We are developing polyelectrolyte complexes of DNA with cationic polyamidoamines (PAA) as a delivery system. Complexing PAA with DNA results in good transfection of cells in vitro. However, in vivo, a more complex arrangement of PAA, Polyethylene glycol-PAA copolymers, DNA and the use of ligands will be required. Despite these efforts, further developments will be needed in nanotechnology for both drug and DNA nanoparticle delivery systems to achieve our clinical objectives.
TEMPERATURE-INDUCED SURFACE STRUCTURE TRANSFORMATION OF SELF-ASSEMBLED MONOLAYERS ON Au(111): A VARIABLE TEMPERATURE STM STUDY
Authors: GUO Q. , SUN X. , PALMER R. E.
Published: February 2006

The structural transformations of self-assembled dodecanethiol monolayers on the Au (111) surface have been studied using variable temperature scanning tunnelling microscopy (STM) in vacuum. Dark lines were observed to form at 350 K, followed by the completion of a rather regular zebra-stripe pattern at 360 K. The stripes have three distinct orientations, reflecting the three-fold symmetry of the substrate. There is continuous material transfer between the stripes at 360–390 K, leading to a constant change of shape of the individual stripes. The average width of the strips stays rather constant at ~ 5 nm. At 390 K, the zebra-stripe structure becomes unstable due to the desorption of thiol molecules.
ELECTRONIC STRUCTURE OF SEMICONDUCTOR NANOCRYSTALS: AN ACCURATE TIGHT-BINDING DESCRIPTION
Authors: SAPRA SAMEER , VISWANATHA RANJANI , SARMA D. D.
Published: February 2006

We report a quantitatively accurate description of the electronic structure of semiconductor nanocrystals using the sp3d5 orbital basis with the nearest neighbor and the next nearest neighbor interactions. The use of this model for II–VI and III–V semiconductors is reviewed in article. The excellent agreement of the theoretical predictions with the experimental results establishes the feasibility of using this model for semiconductor nanocrystals.
ANALYSIS OF BANDWIDTH AND NONLINEAR EFFECTS IN InGaAs-BASED BALLISTIC NANODEVICES FOR APPLICATIONS UP TO THz RANGE
Authors: RASHMI  , BEDNARZ L. , GENCE L. , HACKENS B. , BOUTRY H. , BAYOT V. , HUYNEN I.
Published: February 2006

Analysis of nonlinear effects in InAlAs/InGaAs -based channels and three-terminal ballistic junctions (TBJs) is performed for applications up to THz range. Results show that InGaAs -based channels designed for ballistic operation exhibit high intrinsic cut-off frequency (fT ~ 10 THz ). Nonlinear effects in TBJs, which result from device geometry and space charge distribution, show good qualitative agreement with published results.
POINCARÉ GAUGE GRAVITY: SELECTED TOPICS
Authors: OBUKHOV YURI N.
Published: February 2006

In the gauge theory of gravity based on the Poincaré group (the semidirect product of the Lorentz group and the spacetime translations) the mass (energy–momentum) and the spin are treated on an equal footing as the sources of the gravitational field. The corresponding spacetime manifold carries the Riemann–Cartan geometric structure with the nontrivial curvature and torsion. We describe some aspects of the classical Poincaré gauge theory of gravity. Namely, the Lagrange–Noether formalism is presented in full generality, and the family of quadratic (in the curvature and the torsion) models is analyzed in detail. We discuss the special case of the spinless matter and demonstrate that Einstein's theory arises as a degenerate model in the class of the quadratic Poincaré theories. Another central point is the overview of the so-called double duality method for constructing of the exact solutions of the classical field equations.
Living history of physiology: Bodil Schmidt-Nielsen
Authors: Dantzler William H.
Published: February 2006

In 2005, The American Physiological Society initiated The Living History of Physiology Project to recognize senior members who have made extraordinary contributions during their career to the advancement of the discipline and profession of physiology. Each physiologist will be interviewed for archival purposes, and the video tape will be available from the American Physiological Society Headquarters. In addition, a biographical profile of the recipient will be published in Advances in Physiology Education.
Formative assessment can be fun as well as educational
Authors: Hudson J. N. , Bristow D. R.
Published: February 2006

An understanding of the hormonal basis of normal growth and development, including the changes occurring at puberty, is important foundation knowledge for contemporary medical practice in most fields of medicine. A quiz, testing the important physiological concepts of growth and puberty, was designed using the format of the well-known television game “Who Wants to Be a Millionaire.” An evaluation of this formative assessment activity revealed that a cohort of first-year undergraduate medical students valued learning with peers in an enjoyable, interactive environment, where they were able to admit to uncertainties and clarify answers. It also showed that making an educational activity fun need not detract from the focus of giving feedback on learning. Formative assessment, known to produce learning gains in a range of educational settings, is an important activity in contemporary medical education. With a greater emphasis on self-directed learning and less well-defined curriculum boundaries, feedback helps students to understand and apply the important physiological concepts that underpin the practice of medicine.
Curriculum development and technology incorporation in teaching neuroscience to graduate students in a medical school environment
Authors: Brann Darrell W. , Sloop Shawnee
Published: February 2006

Today's neuroscience faculty member wears multiple hats and requires diverse skills to succeed in the competitive environment in which they find themselves. A common refrain from graduates is that there is a need for better training in the diverse, multiple skills that they will need to succeed in obtaining a faculty position and excelling in that position once it is obtained. Our university recently developed a new neuroscience graduate program that allowed us to create a curriculum and core courses de novo and that could be tailored to provide training in diverse skills used by everyday neuroscience faculty members. The current article details our rationale, design, and implementation of this new curriculum and its two major core courses. The genesis of the new curriculum also provided an opportune time to introduce and test new teaching technology in the two neuroscience core courses. The technology incorporated included on-line WebCT course sites, computer performance system, and the Tegrity system. Herein, we elaborate on our experiences with the use of this technology in the small class graduate course setting and provide insight on student feedback on the perceived effectiveness of the technology. The mechanisms and considerations that are needed for incorporation of such technology are also discussed. While no single curriculum or technology incorporation scheme will be applicable to all programs, it is hoped that our experiences in curriculum design and technology incorporation will be beneficial to other universities as they consider refining existing programs or beginning new ones.
Role of AKT in cyclic strain-induced endothelial cell proliferation and survival
Authors: Nishimura Kengo , Li Wei , Hoshino Yuji , Kadohama Takayuki , Asada Hidenori , Ohgi Shigetsugu , Sumpio Bauer E.
Published: February 2006

Endothelial cells (ECs) are exposed to repetitive cyclic strain (CS) in vivo by the beating heart. The aim of this study was to assess the influence of CS amplitude and/or frequency on EC proliferation and survival and to determine the role of AKT in CS-induced EC proliferation and survival. Cultured bovine aortic ECs were exposed to 10% strain at a frequency of 60 (60 cpm-10%) or 100 (100 cpm-10%) cycles/min or 15.6% strain at a frequency of 60 cycles/min (60 cpm-15.6%). AKT, glycogen synthase kinase (GSK)-3β, BAD, and cleaved caspase-3 were activated by CS in ECs. Increasing the magnitude or frequency of strain resulted in an earlier phosphorylation of GSK-3β, although the magnitude of phosphorylation was similar. After CS at 60 cpm-10% for 24 h, the number of nontransfected ECs was significantly increased by 8.5% ( P < 0.05). We found that the number of apoptotic ECs was slightly decreased with exposure to CS. ECs transfected with kinase-dead AKT (KA179) as well as plasmids containing a point mutation in the pleckstrin homology domain of AKT (RC25) not only prevented AKT, GSK-3β, and BAD phosphorylation but also inhibited the CS-induced increase in cell number as well as the CS-induced protection against apoptosis (both P < 0.05). The ratio of 5′-bromo-2′-deoxyuridine-positive cells was increased when ECs transfected with RC25 and KA179 as well as nontransfected ECs and ECs transfected with Lipofectamine 2000 were exposed to CS. We conclude that AKT is important in enhancing the survival of ECs exposed to CS but is not involved in EC proliferation.
Stable gene silencing of synaptotagmin I in rat PC12 cells inhibits Ca2+-evoked release of catecholamine
Authors: Moore Johnnie M. , Papke Jason B. , Cahill Anne L. , Harkins Amy B.
Published: February 2006

Synaptotagmin (syt) I is a Ca2+-binding protein that is well accepted as a major sensor for Ca2+-regulated release of transmitter. However, controversy remains as to whether syt I is the only protein that can function in this role and whether the remaining syt family members also function as Ca2+ sensors. In this study, we generated a PC12 cell line that continuously expresses a short hairpin RNA (shRNA) to silence expression of syt I by RNA interference. Immunoblot and immunocytochemistry experiments demonstrate that expression of syt I was specifically silenced in cells that stably integrate the shRNA-syt I compared with control cells stably transfected with the empty shRNA vector. The other predominantly expressed syt isoform, syt IX, was not affected, nor was the expression of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins when syt I levels were knocked down. Resting Ca2+ and stimulated Ca2+ influx imaged with fura-2 were not altered in syt I knockdown cells. However, evoked release of catecholamine detected by carbon fiber amperometry and HPLC was significantly reduced, although not abolished. Human syt I rescued the release events in the syt I knockdown cells. The reduction of stimulated catecholamine release in the syt I knockdown cells strongly suggests that although syt I is clearly involved in catecholamine release, it is not the only protein to regulate stimulated release in PC12 cells, and another protein likely has a role as a Ca2+ sensor for regulated release of transmitter.
Glycogen branches out: new perspectives on the role of glycogen metabolism in the integration of metabolic pathways
Authors: Greenberg Cynthia C. , Jurczak Michael J. , Danos Arpad M. , Brady Matthew J.
Published: February 2006

Glycogen is the storage form of carbohydrate for virtually every organism from yeast to primates. Most mammalian tissues store glucose as glycogen, with the major depots located in muscle and liver. The French physiologist Claude Bernard first identified a starch-like substance in liver and muscle and coined the term glycogen, or “sugar former,” in the 1850s. During the 150 years since its identification, researchers in the field of glycogen metabolism have made numerous discoveries that are now recognized as significant milestones in biochemistry and cell signaling. Even so, more questions remain, and studies continue to demonstrate the complexity of the regulation of glycogen metabolism. Under classical definitions, the functions of glycogen seem clear: muscle glycogen is degraded to generate ATP during increased energy demand, whereas hepatic glycogen is broken down for release of glucose into the bloodstream to supply other tissues. However, recent findings demonstrate that the roles of glycogen metabolism in energy sensing, integration of metabolic pathways, and coordination of cellular responses to hormonal stimuli are far more complex.
Regulation of plasma vasopressin and renin activity in conscious hindlimb-unloaded rats
Authors: Mueller Patrick J. , Sullivan Margaret J. , Grindstaff Regina R. , Cunningham J. Thomas , Hasser Eileen M.
Published: February 2006

Cardiovascular deconditioning occurs in astronauts after spaceflight or in individuals subjected to bed rest. It is characterized by an increased incidence of orthostatic intolerance. The mechanisms responsible for orthostatic intolerance are likely multifactorial and may include hypovolemia, autonomic dysfunction, and vascular and cardiac alterations. The arterial baroreflex is an important compensatory mechanism in the response to an orthostatic stress. In a previous study, we demonstrated that arterial baroreflex mediated sympathoexcitation was blunted in hindlimb-unloaded (HU) rats, a model of cardiovascular deconditioning. The arterial baroreflex also contributes to the regulation of vasoactive hormones including vasopressin and angiotensin II. In the present study, we tested the hypothesis that the neurohumoral response to hypotension is also attenuated in rats after 14 days of hindlimb unloading. To test this hypothesis, the vasodilator diazoxide (15 or 25 mg/kg) or saline (0.9%) was administered to produce hypotension or control conditions, respectively, in conscious HU and control rats. Plasma samples were collected and assayed for vasopressin and plasma renin activity (PRA). Diazoxide (25 mg/kg) produced significant increases in vasopressin and PRA compared with saline controls. HU rats exhibited significantly higher levels of vasopressin at rest and the increase in vasopressin levels during hypotension was enhanced by hindlimb unloading. Neither resting nor hypotension-induced PRA was altered by hindlimb unloading. These data suggest that although baroreflex-mediated sympathoexcitation is blunted by hindlimb unloading, hypotension-induced vasopressin release is enhanced and hypotension-induced PRA is unaffected. Increased circulating vasopressin may serve to compensate for blunted baroreflex regulation of sympathetic nervous activity produced by hindlimb unloading or may actually contribute to it.
Ryanodine Receptor Regulates Endogenous Cannabinoid Mobilization in the Hippocampus
Authors: Isokawa Masako , Alger Bradley E.
Published: February 2006

Endogenous cannabinoids (eCBs) are produced and mobilized in a cytosolic calcium ([Ca2+]i)–dependent manner, and they regulate excitatory and inhibitory neurotransmitter release by acting as retrograde messengers. An indirect but real-time bioassay for this process on GABAergic transmission is DSI (depolarization-induced suppression of inhibition). The magnitude of DSI correlates linearly with depolarization-induced increase of [Ca2+]ithat is thought to be initiated by Ca2+influx through voltage-gated Ca2+channels. However, the identity of Ca2+sources involved in eCB mobilization in DSI remains undetermined. Here we show that, in CA1 pyramidal cells, DSI-inducing depolarizing voltage steps caused Ca2+-induced Ca2+release (CICR) by activating the ryanodine receptor (RyR) Ca2+-release channel. CICR was reduced, and the remaining increase in [Ca2+]iwas less effective in generating DSI, when the RyR antagonists, ryanodine or ruthenium red, were applied intracellularly, or the Ca2+stores were depleted by the Ca2+-ATPase inhibitors, cyclopiazonic acid or thapsigargin. The CICR-dependent effects were most prominent in cultured or immature acute slices, but were also detectable in slices from adult tissue. Thus we suggest that voltage-gated Ca2+entry raises local [Ca2+]isufficiently to activate nearby RyRs and that the resulting CICR plays a critical role in initiating eCB mobilization. RyR may be a key molecule for the depolarization-induced production of eCBs that inhibit GABA release in the hippocampus.
KCNQ/Kv7 Channel Regulation of Hippocampal Gamma-Frequency Firing in the Absence of Synaptic Transmission
Authors: Piccinin S. , Randall A. D. , Brown J. T.
Published: February 2006

Synchronous neuronal firing can be induced in hippocampal slices in the absence of synaptic transmission by lowering extracellular Ca2+and raising extracellular K+. However, the ionic mechanisms underlying this nonsynaptic synchronous firing are not well understood. In this study we have investigated the role of KCNQ /Kv7 channels in regulating this form of nonsynaptic bursting activity. Incubation of rat hippocampal slices in reduced (<0.2 mM) [Ca2+]oand increased (6.3 mM) [K+]o, blocked synaptic transmission, increased neuronal firing, and led to the development of spontaneous periodic nonsynaptic epileptiform activity. This activity was recorded extracellularly as large (4.7 ± 1.9 mV) depolarizing envelopes with superimposed high-frequency synchronous population spikes. These intraburst population spikes initially occurred at a high frequency (about 120 Hz), which decayed throughout the burst stabilizing in the gamma-frequency band (30–80 Hz). Further increasing [K+]oresulted in an increase in the interburst frequency without altering the intraburst population spike frequency. Application of retigabine (10 μM), a Kv7 channel modulator, completely abolished the bursts, in an XE-991–sensitive manner. Furthermore, application of the Kv7 channel blockers, linopirdine (10 μM) or XE-991 (10 μM) alone, abolished the gamma frequency, but not the higher-frequency population spike firing observed during low Ca2+/high K+bursts. These data suggest that Kv7 channels are likely to play a role in the regulation of synchronous population firing activity.
Selection and Maintenance of Saccade Goals in the Human Frontal Eye Fields
Authors: Curtis Clayton E. , D'Esposito Mark
Published: February 2006

In a delayed-response task, response selection marks an important transition from sensory to motor processing. Using event-related functional magnetic resonance imaging, we imaged the human brain during performance of a novel delayed-saccade task that isolated response selection from visual encoding and motor execution. The frontal eye fields (FEFs) and intraparietal sulcus (IPS) both showed robust contra-lateralized activity time-locked to response selection. Moreover, response selection affected delay-period activity differently in these regions; it persisted throughout the memory delay period following response selection in the FEF but not IPS. Our results indicate that the FEF and IPS both make important but distinct contributions to spatial working memory. The mechanism that the FEF uses to support spatial working memory is tied to the selection and prospective coding of saccade goals, whereas the role of the IPS may be more tied to retrospective coding of sensory representations.
Effect of Pharmacological Inactivation of Nucleus Reticularis Tegmenti Pontis on Saccadic Eye Movements in the Monkey
Authors: Kaneko Chris R. S. , Fuchs Albert F.
Published: February 2006

The superior colliculus (SC) provides signals for the generation of saccades via a direct pathway to the brain stem burst generator (BG). In addition, it sends saccade-related activity to the BG indirectly through the cerebellum via a relay in the nucleus reticularis tegmenti pontis (NRTP). Lesions of the oculomotor vermis, lobules VIc and VII, and inactivation of the caudal fastigial nucleus, the cerebellar output nucleus to which it projects, produce saccade dysmetria but have little effect on saccade peak velocity and duration. We expected similar deficits from inactivation of the NRTP. Instead, injections as small as 80 nl into the NRTP first slowed ipsiversive saccades and then gradually reduced their amplitudes. Postinjection saccades had slower peak velocities and longer durations than preinjection saccades with similar amplitudes. Contraversive saccades retained their normal kinematics. When the gains of ipsiversive saccades to 10° target steps had fallen to their lowest values (0.28 ± 0.19; mean ± SD; n = 10 experiments), the gains of contraversive saccades to 10° target steps had decreased very little (0.82 ± 0.11). Eventually, ipsiversive saccades did not exceed 5°, even to 20° target steps. Moreover, these small remaining saccades apparently were made with considerable difficulty because their latencies increased substantially. When ipsiversive saccade gain was at its lowest, the gain and kinematics of vertical saccades to 10° target steps exhibited inconsistent changes. We argue that our injections did not compromise the direct SC pathway. Therefore these data suggest that the cerebellar saccade pathway does not simply modulate BG activity but is required for horizontal saccades to occur at all.
New Modalities and Aspects of Antiplatelet Therapy for Stroke Prevention
Authors: Uchiyama Shinichiro , Nakamura Tomomi , Yamazaki Masako , Kimura Yumi , Iwata Makoto
Published: February 2006

Antiplatelet therapy is indicated for secondary prevention of ischaemic stroke. The first-line antiplatelet agent is aspirin. The effect of aspirin is, however, very limited, and this limited effect of aspirin is argued with termed ‘aspirin resistance’. Strategies against aspirin resistance may include alternative use of other antiplatelet agents, combination of aspirin with other antiplatelet agents and investigation into molecular targets to develop novel antiplatelet agents. Progress in antiplatelet therapy should be directed at further reducing the risk of ischaemic events including ischaemic stroke without increasing the risk of haemorrhagic events including haemorrhagic stroke.
Rosai-Dorfman Disease Presenting as Bilateral Eyelid Swellings
Authors: Jogai Sanjay , Temmim Labiba , Al-Baghli Abdullah , Adesina Aaron Olaolu
Published: February 2006

Objective: To report a case of sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease) in an extranodal site with unusual presentation. Case Presentation: A 19-year-old girl presented with bilateral upper eyelid swellings of 2 years duration due to tumor. The masses were excised and sent for histopathological examination. Microscopic examination revealed similar features in both masses in the form of a collection of large histiocytic cells showing emperipolesis (lymphocytophagocytosis). The histiocytic cells stained positively with S-100 protein and CD68. The background comprised small lymphocytes and plasma cells. Based on the overall features a diagnosis of sinus histiocytosis with massive lymphadenopathy or Rosai-Dorfman disease was made. Conclusion: The present case highlights one of the forms in which extranodal Rosai-Dorfman disease can manifest itself. It is important to keep this differential diagnosis in mind whenever such histopathological features are encountered.
Monitoring of Lung Edema by Microwave Reflectometry during Lung Ischemia-Reperfusion Injury in vivo
Authors: Nowak Kai , Schaefer Michael , Gross Wolfgang , Metzger Roman Patrick , Hohenberger Peter , Post Stefan , Gebhard Martha Maria
Published: February 2006

It is still unclear whether lung edema can be monitored by microwave reflectometry and whether the measured changes in lung dry matter content (DMC) are accompanied by changes in PaO2 and in pro- to anti-inflammatory cytokine expression (IFN-γ and IL-10). Right rat lung hili were cross-clamped at 37°C for 0, 60, 90 or 120 min ischemia followed by 120 min reperfusion. After 90 min (DMC: 15.9 ± 1.4%; PaO2: 76.7 ± 18 mm Hg) and 120 min ischemia (DMC: 12.8 ± 0.6%; PaO2: 43 ± 7 mm Hg), a significant decrease in DMC and PaO2 throughout reperfusion compared to 0 min ischemia (DMC: 19.5 ± 1.11%; PaO2: 247 ± 33 mm Hg; p < 0.05) was observed. DMC and PaO2 decreased after 60 min ischemia but recovered during reperfusion (DMC: 18.5 ± 2.4%; PaO2: 173 ± 30 mm Hg). DMC values reflected changes on the physiological and molecular level. In conclusion, lung edema monitoring by microwave reflectometry might become a tool for the thoracic surgeon.
Magnetic Resonance Evaluation of the Cerebral Circulation in Obstructive Arterial Disease
Authors: van Laar Peter Jan , van der Grond Jeroen , Mali Willem P.T.M. , Hendrikse Jeroen
Published: February 2006

Background: The aim of the current overview is to highlight the possibilities of magnetic resonance imaging (MRI) in the assessment of patients with obstructive arterial disease. The anatomic and hemodynamic aspects of the extra- and intracranial cerebral circulation were analyzed and show the importance of combining both aspects in studying cerebral hemodynamic changes. Results: Three levels of cerebral circulation are distinguished: blood flow to the brain (level 1); the distribution of blood flow in the brain (level 2), and finally perfusion of the brain (level 3). To investigate the anatomy of the arteries in the neck and the circle of Willis, contrast-enhanced, time-of-flight and phase contrast MR angiography (MRA) are available. To evaluate the hemodynamics at the 1st and 2nd level of the cerebral circulation two-dimensional phase contrast (volume flow and flow direction) MRA can be used. In addition, the distribution of blood via the circle of Willis can be visualized with dynamic MRA. At the 3rd level, measurements of regional brain perfusion can be obtained by injecting gadolinium, dynamic susceptibility contrast MRI, or noninvasively with arterial spin labeling (ASL) MRI. In addition, selective ASL MRI is able to evaluate the perfused territories of individual brain-feeding arteries. Conclusion: The currently available MR techniques allow evaluation of the cerebral circulation from the aortic arch upwards towards the microvasculature and brain tissue perfusion in a comprehensive 20-min protocol. The combined use of the described MR methods in patients with steno-occlusive disease will further clarify the pathophysiological relations between the vasculature, perfusion and brain function.
Is Japan's Cultural Experience Relevant for Africa's Development?
Authors: Adem Seifudein
Published: February 2006

Japan broke a new path of modernization when it became the first successfully-industrialized nation in the non-Western world. Therefore Japan's modernization experience has a wider relevance for Africa and beyond. The objective of this paper is, however, to single out and discuss only the role of cultural factors in the process and then consider the implications for Africa's development. A conclusion is then drawn – that is, Japan's historical experience strongly suggests that Africa's own cultures have a greater relevance for Africa's development. What does this mean, and why is it so? The paper addresses these questions.
"Perversion de l'Histoire": George Balandier, his disciples, and African History in Japan
Authors: Philips John Edward
Published: February 2006

Japan's quest for a permanent United Nations Security Council seat could be expected to lead to an increased importance for foreign language and area studies in Japan, as it did in the United States. This is particularly the case with Japan, an insular nation proud of its homogeneity with little history of immigration. Despite the inherently greater difficulties for Japan in trying to understand the outside world, there has been little increase in attempts to understand the outside world when compared to the efforts made by the United States, which started with several advantages over Japan. The example of African history is a case study of Japan's failure to interact with the wider world of international scholarship and its perpetuation of discredited ideas.
Trade Unionism: Differences and Similarities - a Comparative View on Europe, USA and Asia
Authors: Jensen Carsten Strøby
Published: February 2006

The article presents an outline of characteristics regarding trade unions in three different parts of the world, focusing on Europe, USA and Asia. The intention is to describe and discuss differences and similarities between trade unionism in these three parts of the world focusing on some selected countries. The conclusion in this article is that it is possible - on a very abstract and generalizing level - to identify some differences in the social and institutional basis of trade unions in Europe, Asia and the USA.
Employment Relations Across the Taiwan Strait: Globalization and State Corporatism
Authors: Chang Chyi-herng , Bain Trevor
Published: February 2006

After the 1980s, the governments of China and Taiwan, across the Taiwan Strait, promoted reform, a more transparent policy, and democratization, in order to compete in a globalizing world. In the 1980s, China had begun to emphasize economic reform and Taiwan had begun to emphasize political reform. Both ignored reform on the social dimension. Employment relations were subordinated to the priorities of economic and political reform. In the 1990s, Taiwan’s democratic transformation created a pluralistic society and gave the trade unions room to take root. However, free collective bargaining has not been realized due to the marginalizing of both employer organizations and trade unions. In China, the state decentralized the business sector, allowing unilateral employer activities in employment relations. Statutory rules were enacted after the 1994 labor law. This article compares the changes that have taken place in the industrial relations systems in Taiwan and China, and assesses the roles of the two governments in the employment relations area as each responded to globalization.
Migration and Imperialism
Authors: Wise Raúl Delgado
Published: February 2006

The process of economic integration occurring as a result of the North American Free Trade Agreement (NAFTA) has created a new migratory dynamic between Mexico and the United States. Under the aegis of neoliberalism, the Mexican workforce is being called upon to play a crucial role in the industrial restructuring of the United States and thus creates obstacles for development in Mexico. In the face of this reality, the migrant community is generating new social actors and alternative paths that, though incipient, begin to challenge this model of integration.