bluuebunny/crossref_metadata_2025_split huggingface dataset:
NEURAL EXCITABILITY, SPIKING AND BURSTING
Authors: IZHIKEVICH EUGENE M. 
Published: May 2003

Bifurcation mechanisms involved in the generation of action potentials (spikes) by neurons are reviewed here. We show how the type of bifurcation determines the neuro-computational properties of the cells. For example, when the rest state is near a saddle-node bifurcation, the cell can fire all-or-none spikes with an arbitrary low frequency, it has a well-defined threshold manifold, and it acts as an integrator; i.e. the higher the frequency of incoming pulses, the sooner it fires. In contrast, when the rest state is near an Andronov–Hopf bifurcation, the cell fires in a certain frequency range, its spikes are not all-or-none, it does not have a well-defined threshold manifold, it can fire in response to an inhibitory pulse, and it acts as a resonator; i.e. it responds preferentially to a certain (resonant) frequency of the input. Increasing the input frequency may actually delay or terminate its firing. We also describe the phenomenon of neural bursting, and we use geometric bifurcation theory to extend the existing classification of bursters, including many new types. We discuss how the type of burster defines its neuro-computational properties, and we show that different bursters can interact, synchronize and process information differently.
POINT SET LABELING WITH SPECIFIED POSITIONS
Authors: DODDI SRINIVAS R. , MARATHE MADHAV V. , MORET BERNARD M. 
Published: May 2003

Motivated by applications in cartography and computer graphics, we study a version of the map-labeling problem that we call the k-Position Map-Labeling Problem: given a set of points in the plane and, for each point, a set of up to k allowable positions, place uniform and non-intersecting labels of maximum size at each point in one of the allowable positions. This version combines an aesthetic criterion and a legibility criterion and comes close to actual practice while generalizing the fixed-point and slider models found in the literature. We present a general heuristic that given an ∊ > 0, runs in time O(n log n + n log (R*/ ∊) log (k)), where R* is the size of the optimal label, and guarantees a constant approximation for any regular labels. For circular labels, our technique yields a (3.6 + ∊)-approximation, improving in the case of arbitrary placement over the previous bound of approximately 19.5 obtained by Strijk and Wolff.28 We then extend our approach to arbitrary positions, obtaining an algorithm that is easy to implement and also substantially improves the best approximation bounds. Our technique combines several geometric and combinatorial properties, which may be of independent interest.
A SHORTEST PAIR OF PATHS ON THE PLANE WITH OBSTACLES AND CROSSING AREAS
Authors: KUSAKARI YOSHIYUKI , SUZUKI HITOSHI , NISHIZEKI TAKAO 
Published: May 2003

Given obstacles and crossing areas together with two pairs of terminals on the plane, our algorithm finds a pair of rectilinear paths which connect the pairs of terminals, neither pass through any obstacle nor cross each other except in the crosssing areas, and minimize the total length, where all obstacles and crossing areas are assumed to be axis-parallel rectangles. The algorithm takes O(n log n) time and O(n) space, where n is the total number of obstacles and crossing areas.
ISOMORPHIC TRIANGULATIONS WITH SMALL NUMBER OF STEINER POINTS
Authors: KRANAKIS EVANGELOS , URRUTIA JORGE 
Published: May 2003

Assume that an isomorphism between two n-vertex simple polygons, P,Q (with k,l reflex vertices, respectively) is given. We present two algorithms for constructing isomorphic (i.e. adjacency preserving) triangulations of P and Q, respectively. The first algorithm computes isomorphic triangulations of P and Q by introducing at most O((k+l)2) Steiner points and has running time O(n+(k+l)2). The second algorithm computes isomorphic traingulations of P and Q by introducing at most O(kl) Steiner points and has running time O(n+kl log n). The number of Steiner points introduced by the second algorithm is also worst-case optimal. Unlike the O(n2) algorithm of Aronov, Seidel and Souvaine1 our algorithms are sensitive to the number of reflex vertices of the polygons. In particular, our algorithms have linear running time when [Formula: see text] for the first algorithm, and kl≤n/ log n for the second algorithm.
PARALLEL CONSTRUCTION OF QUADTREES AND QUALITY TRIANGULATIONS
Authors: BERN MARSHALL , EPPSTEIN DAVID , Teng Shang-Hua 
Published: May 2003

We describe efficient PRAM algorithms for constructing unbalanced quadtrees, balanced quadtrees, and quadtree-based finite element meshes. Our algorithms take time O(log n) for point set input and O(log n log k) time for planar straight-line graphs, using O(n+k/log n) processors, where n measures input size and k output size.
INERTIAL MASS FROM SPIN NONLINEARITY
Authors: COHEN MARCUS 
Published: May 2003

The inertial mass of a Fermion shows up as chiral cross-coupling in its Dirac system. No scalar term can invariantly couple left and right chirality fields; the Dirac matrices must be spin tensors of mixed chirality. We show how such tensor couplings could arise from nonlinear mixing of four spinor fields, two representing the local electron fields and two inertial spinor fields sourced in the distant masses. We thus give a model that implements Mach's principle. Following Mendel Sachs,1 we let the inertial spinors factor the moving spacetime tetrads qα(x) and [Formula: see text] that appear in the Dirac operator. The inertial spinors do more than set the spacetime "stage;" they are players in the chiral dynamics. Specifically, we show how the massive Dirac system arises as the envelope modulation equations coupling left and right chirality electron fields on a Friedmann universe via nonlinear "spin gratings" with the inertial spinor fields. These gratings implement Penrose's "mass-scatterings," which keep the null zig-zags of the bispinor wave function confined to a timelike world tube. Local perturbations to the inertial spinor fields appear in the Dirac system as Abelian and non-Abelian vector potentials.
MAXWELL FIELDS IN ANISOTROPIC SPACETIMES
Authors: WOLLENSAK MATTHIAS 
Published: May 2003

Maxwell's equations are rewritten with respect to anholonomic orthonormal frames and applied to the case when the background is described by a diagonal Bianchi Type I universe with line element [Formula: see text]. It is generally shown that solutions analogous to plane wave solutions in flat spacetime must obey two transversality conditions when the spacetime is anisotropic i.e., when at least one of the coefficients αj(t) differs from the others. Analytic solutions are presented for propagation along the respective coordinate axes and a special stiff fluid model. Furthermore, by use of a generally applicable ansatz the long- and short-time behavior of waves traveling in the axisymmetric Kasner universe have been investigated.
MANUFACTURING SYSTEMS MODELLING USING SYSTEM DYNAMICS: FORMING A DEDICATED MODELLING TOOL
Authors: OYARBIDE A. , BAINES T. S. , KAY J. M. , LADBROOK J. 
Published: May 2003

Discrete event simulation is a popular aid for manufacturing system design; however in application this technique can sometimes be unnecessarily complex. This paper is concerned with applying an alternative technique to manufacturing system design which may well provide an efficient form of rough-cut analysis. This technique is System Dynamics, and the work described in this paper has set about incorporating the principles of this technique into a computer based modelling tool that is tailored to manufacturing system design. This paper is structured to first explore the principles of System Dynamics and how they differ from Discrete Event Simulation. The opportunity for System Dynamics is then explored, and this leads to defining the capabilities that a suitable tool would need. This specification is then transformed into a computer modelling tool, which is then assessed by applying this tool to model an engine production facility.
DISTRIBUTED MANUFACTURING SIMULATION AS AN ENABLING TECHNOLOGY FOR THE DIGITAL FACTORY
Authors: STRASSBURGER STEFFEN , SCHMIDGALL GÜNTER , HAASIS SIEGMAR 
Published: May 2003

In this article the technological possibilities offered by the interoperability standard High Level Architecture (HLA) are introduced and discussed. The main focus is hereby on manufacturing applications, but the same approach is applicable to a wide range of other scenarios, e.g. in the area of supply chains, logistics, product simulation etc. Especially for challenging objectives like the digital factory which many enterprises are currently facing, simulation applications are gaining growing importance. While simulations nowadays are often still applied for isolated problems, the consideration of the global context has a growing importance. A solution for solving this problem is offered by the distributed simulation paradigm: simulations are no longer single purpose applications. Rather, individual simulation models can be combined with each other for serving different purposes. Coupled simulations of different parts of a factory can be used to perform global optimizations. The same paradigm can be used for entire supply chains. For applying the distributed simulation paradigm, technological as well as organizational aspects have to be considered. On the technological side, it is necessary to integrate a certain interoperability standard into the tools which need to be coupled with each other. On the organizational level, an enterprise wide process has to be established, which defines how distributed modeling and simulation shall be applied. This article discusses solutions for both issues and illustrates them using a practical application scenario.
THE APPLICATION OF MODERN SOFTWARE ENGINEERING PRACTICES TO CONTROL ENGINEERING
Authors: BERENBACH BRAIN A. , SPOOL PETER R. , BITTERLE DIETER 
Published: May 2003

Over the years, control systems have become increasingly dependent on custom software. As hardware has gotten cheaper, attention has focused on improving the processes associated with developing control system software by using approaches such as the Software Engineering Institute's Capability Maturity Model (CMM),1,2 and enabling reuse and long term cost reduction with component-based software development. This paper discusses the application of the CMM to the software process used in control engineering and the use of component based software development. We also discuss some advanced features of the Siemens SIMATIC STEP 7 Universal Development Environment that provides the tools to plan, configure, evelop, test, troubleshoot, document and support not only PLC programs, but also entire auto, ation projects. STEP 7 also enables and support process improvement and component-based software development.
Lysosomal Enzymes Are Released From Cultured Human Macrophages, Hydrolyze LDL In Vitro, and Are Present Extracellularly in Human Atherosclerotic Lesions
Authors: Hakala Jukka K. , Oksjoki Riina , Laine Petri , Du Hong , Grabowski Gregory A. , Kovanen Petri T. , Pentikäinen Markku O. 
Published: May 2003

Objective—Human atherosclerotic lesions have been shown to contain lipid droplets and vesicles resembling those of in vitro enzymatically modified LDL. However, little is known about the hydrolytic enzymes in the arterial intima that induce fusion of LDL particles and so produce lipid droplets or that induce foam cell formation.Methods and Results—Human coronary atherosclerotic lesions obtained at surgery and at autopsy were stained for lysosomal acid lipase and cathepsin D. The extracellular areas of macrophage-rich intimal regions of the atherosclerotic lesions stained positively for both cathepsin D and lysosomal acid lipase, whereas normal arteries were negative. When monocyte-derived macrophages were incubated with opsonized zymosan to stimulate the release of lysosomal enzymes from the cells and LDL was incubated with the macrophage-conditioned media, the apolipoprotein B-100, cholesteryl esters, and triacylglycerols of LDL were hydrolyzed. These hydrolytic modifications rendered the LDL particles unstable and induced their fusion. Cultured macrophages and smooth muscle cells took up the hydrolase-modified LDL particles avidly and were transformed into foam cells.Conclusions—Our in vivo and in vitro results suggest that lysosomal enzymes released from macrophages may induce hydrolytic modification of LDL and foam cell formation in the human arterial intima.
On Embedding Synfire Chains in a Balanced Network
Authors: Aviel Y. , Mehring C. , Abeles M. , Horn D. 
Published: May 2003

We investigate the formation of synfire waves in a balanced network of integrate-and-fire neurons. The synaptic connectivity of this network embodies synfire chains within a sparse random connectivity. This network can exhibit global oscillations but can also operate in an asynchronous activity mode. We analyze the correlations of two neurons in a pool as convenient indicators for the state of the network. We find, using different models, that these indicators depend on a scaling variable. Beyond a critical point, strong correlations and large network oscillations are obtained. We looked for the conditions under which a synfire wave could be propagated on top of an otherwise asynchronous state of the network. This condition was found to be highly restrictive, requiring a large number of neurons for its implementation in our network. The results are based on analytic derivations and simulations.
The influence of familiarity, age, experience and female mate choice on pregnancies in captive grey mouse lemurs
Authors: Radespiel Ute , Zimmermann Elke 
Published: May 2003

Abstract
Conceptions in mammals may depend on a variety of factors including mate familiarity, age, sociosexual experience and female mate choice. We tested predictions for the effects of these factors on pregnancies in a captive colony of grey mouse lemurs (Microcebus murinus). The succession of oestrous cycles and pregnancies was analysed for a total of 26 different females that were housed together with 33 different males over a total of 124 oestrous cycles between 1995 and 2001. In addition, sexual behaviours were recorded and analysed over 13 oestrous cycles of 9 different females. An effect of mate familiarity on pregnancies could be detected by a frequent delay of pregnancies to the second cycle of the season (66.7% of the possible cases). Female age influenced pregnancies as the 2-3-year old females were less likely to become pregnant than females of other age classes. This reduced rate of pregnancies, however, was probably due to the lack of previous sociosexual experience with males. Females that have not been housed with males within their first reproductive season, needed one or two years of sociosexual experience before their first successful impregnation. These findings are discussed as a side effect of the ontogenetic development of female dominance. Female mate choice could be deduced from the succession of pregnancies and the strong responsibility of the females for the termination of matings.
The trade-off between singing and mass gain in a daytime-singing bird, the European robin
Authors: Thomas Robert , Goldsmith Arthur , Cuthill Innes , Lidgate Helena , Burdett Proctor Selene , Cosgrove Delia 
Published: May 2003

AbstractThe functions of bird song are well described, but empirical studies examining the costs of singing are scarce. Two potential costs are a metabolic cost of singing, and lost feeding opportunities, but such energetic costs will only be biologically important if they have a significant effect on the bird's body reserves. Overnight loss of reserves has previously been found to increase with increasing song rates in nocturnally singing common nightingales Luscinia megarhynchos. However, it is not clear how such costs compare with those incurred by daytime-singing birds, which may forfeit foraging opportunities when they sing. In this paper we investigated the effect of variation in song rate on the body reserves of a typical daytimesinging bird, the European robin Erithacus rubecula, singing at different rates in three different circumstances: (i) Natural variation in song rate of free-living robins. (ii) Manipulations of the song rate of free-living robins using playbacks of conspecific song. (iii) Manipulations of the song rate of aviary-housed robins using playbacks of conspecific song. In all three parts of our study, birds gained less mass when they sang more. Our analyses suggested that this might have been due primarily to a reduction in food intake rate, rather than to the metabolic cost of the singing itself or a concurrent increase in locomotor costs. These results together demonstrate that the costs of singing, as measured by their overall net effects on body reserves, can have a significant impact on the energetic state of daytime-singing birds.
Male consortship behaviour in chacma baboons: the role of demographic factors and female conceptive probabilities
Authors: Henzi S. Peter , Hill Russell , Barrett Louise , Lycett John , Weingrill Tony 
Published: May 2003

AbstractThere is evidence for a general relationship between male dominance rank and mating success in primates, although the strength of this relationship differs among species. In chacma baboons (Papio hamadryas ursinus) male rank is found to be of more importance than in the other savannah baboon subspecies. However, even though the priority-of-access model explains the proportion of time spent in consortship for males of different rank in chacmas, highest-ranking males usually consort less often than expected. In this study, conducted in the Drakensberg Mountains of Natal and at De Hoop in the Western Cape, we investigated why dominant males in four study troops consorted only between 50% and 75% of days that they were expected to consort according to the priority-of-access model. Consortship success of highest-ranking males was primarily dependant on the number of available oestrous females in a troop. This was likely due to costs involved in consorting which limit the amount of days that a male could spend in consortship. Females pass through several cycles before conceiving and highest-ranking males were observed to consort more often on the conceptive cycle compared to the nearest nonconceptive cycle, but this was only true for males that were already resident for several months. Recently immigrated males that became highest-ranking often consorted during nonconceptive female cycles, while older, lower-ranking males consorted during the conceptive cycles. We propose that males with longer residency have more information about reproductive state of females and thus higher reproductive success than recently immigrated males.
KHARJAS AND VILLANCICOS
Authors: Armistead Samuel 
Published: May 2003

AbstractScholarship surrounding the kharjas, concluding qufls in the Hispano-Romance Mozarabic dialect, appended to muwashshahāt written in Arabic or Hebrew by 11th- to 14th-century Muslim and Jewish authors in al-Andalus, has been characterized by bitterly acrimonious polemics, sometimes involving even personal ad hominem criticism. While the kharjas are indubitably an integral part of the Hispano-Semitic poems in which they have survived, and can and should be legitimately studied within that context, some recent attempts have been put forward to deny that there is any relationship between the Romance kharjas and other manifestations of primitive lyric poetry in Castilian and Galician-Portuguese that are well documented in Medieval Iberia. The present article reviews the available evidence, which undeniably points to an intimate relationship between the Mozarabic verses and Castilian villancicos ("peasant songs") and Old Portuguese cantigas de amigo ("songs about lovers"). Consistent and abundant parallels between the three forms are discussed and exemplified in terms of themes, motifs, metrics, formulaic diction, and traditional "intuitive" style. The kharjas turn out to be crucially important as the earliest known documents of the oral-traditional Romance lyric poetry sung in Medieval Iberia and throughout the Mediterranean world during the Middle Ages and even before. The kharjas are, then, best viewed as essentially amphibious poems that should be productively and collaboratively studied by Arabists, Hebraists, and Hispanists.
THE DĪWĀN OF AL-SHARĪF AL-TALĪQ
Authors: Neale Harry 
Published: May 2003

AbstractThis article presents the reconstructed dīwān of the Andalusī poet Marwān b. Abd al-Rahmān b. Marwān b. Abd al-Rahmān al-Nāsir al-Sharīf al-Talīq (d. 400/1009). This reconstruction has been assembled from fragments of poetry attributed to al-Sharīf al-Talīq that are found in various compilations of biographies of Andalusī poets. The late Spanish scholar, Emilio García Gómez, included translations of a number of these fragments in his study of Andalusī poetry, Cinco poetas musulmanes: biografías y estudios (Madrid: Espana-Calpe, 1944). In addition to presenting the existing fragments of the dīwān, including fragments that García Gómez did not have at his disposal, I undertook a thematic reading of the dīwān with attention to the imagery and motifs that recur within the poems. In this way, I hope to distill a specific voice that is the lyric idiom of this little-studied poet. The frame of reference for the analysis of the dīwān is a fragmentary qāfiyyah by al-Sharīf al-Talīq. This qasīdah has been selected because it offers the most complete repertoire of the imagery and vocabulary of al-Sharīf al-Talīq's poetry available to us.
DOING THINGS WITH ODES: A POET'S PLEDGES OF ALLEGIANCE: IBN DARRĀJ AL-QASTALLĪ'S HĀ'IYYAH TO AL-MANSŪR AND RĀIYYAH TO AL-MUNDHIR
Authors: Al-Mallah Majd Yaser 
Published: May 2003

AbstractThis article analyzes two of Ibn Darrāj al-Qastallī's famous odes presented to al-Mansūr b. Abī 'Āmir (d. 392/1002) and Mundhir b. Yahyā (d. 412/1022). Applying speech act theory reveals that these odes perform the illocutionary act, to use speech act terminology, of obligating the patron to reward the poet as a symbol of establishing a mutual relationship that is based on the poet's pledge of allegiance and the patron's acknowledgment of obligation toward the poet. The analysis focuses on what the panegyric ode does and what effect it has on the poet and patron within a proper context in the community. The paper uses speech act theory as a general framework for the ritual of gift exchange, which consists of giving (the poem as a gift), receiving (the poem by the patron), and repaying (the poet). This ritual establishes specific obligations between poet and patron that allow the panegyric ode to accomplish specific objectives. The paper also compares the function of each of the two odes in the context of the different political circumstances under which they were presented and shows how these circumstances affect the structure of each ode.