bluuebunny/crossref_metadata_2025 huggingface dataset:
SPIN DYNAMICS OF TWO-DIMENSIONAL HUBBARD SYSTEMS
Authors: KO DAVID
Published: November 2004

The discovery of high temperature superconductivity has motivated a vigorous study of the physics of Hubbard systems. Here, the properties of the spin aspects of the Hubbard system in two-dimension, in the strong coupling limit, are briefly reviewed, with the basic ideas, some of the fundamental questions and the state of the art introduced.
GROWTH AND MICROHARDNESS STUDIES OF Ba1−xKxBiO3 SINGLE CRYSTALS
Authors: HEMAMALINI R. , SURESHKUMAR P. , SUBRAMANIAN C. , RAMASAMY P.
Published: November 2004

Single crystals of Ba 1−x K x BiO 3 have been grown by flux technique. The microhardness study revealed that the hardness of BKBO is less than that of YBa 2 Cu 3 O 7−δ. X-ray diffraction studies showed the structure as cubic with lattice parameter a=4.2739 Å for Ba 0.9 K 0.1 BiO 3 and a=4.2667 Å for Ba 0.6K0.4 BiO 3 crystals.
COMPLEX SUSCEPTIBILITY AND CRITICAL CURRENT OF HIGH-TEMPERATURE SUPERCONDUCTORS
Authors: LU G. , CHEN K.X. , XUE L.X. , WEI C.D. , FENG Q.R. , REN H.T. , HE Q. , XIAO L. , WANG R.K. , YU D.A.
Published: November 2004

The ac complex susceptibility χ′−iχ″ of several bulk samples with very high critical current density Jc have been measured. The results show that these samples are all polycrystalline bulk material, the peak of χ″ still related to losses within “the weak link structure” of the intergrain material. But the intergrain coupling strength of the high Jc samples is much stronger than ordinary high-Tc superconductors. A parameter β=(Tc2(0) −Tc2(h0))/h02/3 has been proposed to characterize the coupling strength.
KINETIC PATHWAY IN STRANSKI-KRASTANOV GROWTH OF Ge ON Si(001)
Authors: MO Y.-W. , LAGALLY M.G.
Published: November 2004

Scanning tunneling microscopy studies of the kinetic processes involved in the two-dimensional (2D) to three-dimensional (3D) transition in Stranski-Krastanov growth of Ge on Si(001) reveal a novel type of 3D cluster that serves as the kinetic pathway for this transition.
VARIATION OF Tc IN SINGLE PHASE Bi4Sr3Ca3Cu4O16−x SYSTEM
Authors: KHAN M. NASIR , KHWAJA FARID A.
Published: November 2004

The variation of critical temperature Tc in a single-phased ceramic high temperature superconductor Bi 4 Sr 3 Ca 3 Cu 4 O y is studied using techniques like X-ray diffraction, magnetic and electrical measurements. Samples of Bi-Sr-Ca-CuO having nominal composition 4334 are synthesized by solid state reaction using appropriate amounts of Bi 2O3, SrCO 3, CaCO 3 and CuO powders. It has been shown that the Tc in this material can be raised from 98 K in the fast quenched sample to 120 K in the furnace-cooled one. The higher values of Tc in furnace cooled specimens as compared with the Tc in quenched samples have been attributed to the variation in the interlayer spacing in these compounds. It is concluded that electron density and hence the attractive interaction between pairs are increased due to shortening of the interlayer spacing in the furnace-cooled sample, leading to an increase of its Tc.
EFFECT OF Fe DOPING ON SUPERCONDUCTIVITY IN THE Bi-Pb-Sr-Ca-Cu-O SYSTEM
Authors: DOU S.X. , SHENG Y.J. , LIU H.K. , SORRELL C.C. , SAVVIDES N.
Published: November 2004

The effects of Fe substitution for Cu in Bi1.6Pb0.4Sr1.6Ca2Cu3O10−y were investigated. The superconducting transition, phase assemblage, and lattice parameters were studied for samples with up to ~1/4 of the Cu replaced by Fe. With increasing levels of Fe, the superconducting transition gradually degenerated to that of semiconducting behaviour, the phase assemblage underwent the reaction series 2223→2221→2201, and the c-axis of the 2212 phase decreased monotonically when the doped samples were heat treated in air. These results can be explained in terms of structural changes rather than magnetic effects, where the higher valence and smaller size of Fe3+ compared Cu2+ alter the nature of the oxygen co-ordination and bonding. When the Fe-doped samples were treated in nitrogen, the effect of destabilisation of the superconducting phase was minimised. In contrast to the effect of Fe on the structure, the depression in Tc is attributed mainly to the magnetic effects of Fe doping. The critical concentration of the Fe dopant at which superconductivity was completely destroyed, is at ~13% Cu replacement.
COMPUTER RECOGNITION OF TOTALLY UNCONSTRAINED HANDWRITTEN ZIP CODES
Authors: AHMED PERVEZ , SUEN C. Y.
Published: November 2004

This paper deals with the application of automatic sorting of envelopes with totally unconstrained handwritten numeric postal ZIP codes and presents a complete model (including preprocessing, feature extraction and classification modules) of a ZIP code reader/sorter.

Different recognition methods, including statistical, structural and combined were developed and their performance on real-life ZIP code samples (8540 numerals) were measured.

The statistical recognition method was used as a front-end recognizer and predictor of an unknown character. Based on edge classification, a new technique was implemented to define and extract the structural features.

In the combined recognition method, unknown characters were identified either by the statistical or structural method. Its recognition reliability was found to be in the interval (96.29%, 95.94%) with substitution and rejection rates between (3.45%, 3.96%) and (2.36%, 7.01%) respectively.
A GENERAL FRAMEWORK FOR KNOWLEDGE-BASED PATTERN RECOGNITION
Authors: BERGADANO F. , SAITTA L.
Published: November 2004

This paper surveys a long term project, aimed at providing a general methodology for building up and maintaining an expert system oriented to Pattern Recognition problems. The methodology makes use of an integrated set of modules, performing different functions but sharing a common knowledge representation scheme. In particular, a learning module allows to acquire the knowledge automatically from a set of examples and another module performs sophisticated reasoning, on the basis of the available knowledge, during the recognition phase.
USING EXPERT SYSTEMS FOR IMAGE UNDERSTANDING
Authors: SUETENS P. , OOSTERLINCK A.
Published: November 2004

Expert systems and image understanding have traditionally been considered as two separate application fields of artificial intelligence (AI). In this paper it is shown, however, that the idea of building an expert system for image understanding may be fruitful. Although this paper may serve as a framework for situating existing works on knowledge-based vision, it is not a review paper. The interested reader will therefore be referred to some recommended survey papers in the literature.
INSIGHT: A DATAFLOW LANGUAGE FOR PROGRAMMING VISION ALGORITHMS IN A RECONFIGURABLE COMPUTATIONAL NETWORK
Authors: SHAPIRO LINDA G. , HARALICK ROBERT M. , GOULISH MICHAEL J.
Published: November 2004

Machine vision systems used in industrial applications must execute their algorithms in real time to perform such tasks as inspecting a wire bond or guiding a robot to install a part on a car body moving along a conveyer. The real time speed is achieved by employing simple-minded algorithms and by designing parallel architectures and parallel algorithms for some tasks. The majority of the work on parallel architectures has been limited to architectures that support image processing, but not mid- or high-level vision In order for more complex vision algorithms to execute in real time, a more flexible architecture is needed.

Our conceptual approach to the problem is a reconfigurable computational network. Each configuration of the network implements an algorithm or class of algorithms A high-level language expresses the algorithms in a relational form that can be easily translated to the specification for a configuration. The language must be able to encode low-, mid-, and high-level vision algorithms and to efficiently handle not only pixel data, but also higher level structures. In this paper we describe a dataflow language called INSIGHT, which we have designed to meet these needs, and give several examples of parallel machine vision algorithms expressed in the language.
EARLY ORIENTATION SELECTION—INFERRING TRACE, TANGENT, AND CURVATURE FIELDS
Authors: ZUCKER STEVEN W.
Published: November 2004

Orientation selection is the inference of orientation information out of images. It is one of the foundations on which other visual structures are built, since it must precede the formation of contours out of pointillist data and surfaces out of surface markings. We take a differential geometric view in defining orientation selection and develop algorithms for actually doing it. The goal of these algorithms is formulated in mathematical terms as the inference of a vector field of tangents (to the contours), and the algorithms are studied in both abstract and computational forms. They are formulated as matching problems, and algorithms for solving them are reduced to biologically plausible terms. We show that two different matching problems are necessary, the first for 1-dimensional contours (which we refer to as Type I processes) and the second for 2-dimensional flows (or Type II processes).
VISION APPLICATIONS IN THE FISHING AND FISH PRODUCT INDUSTRIES
Authors: ARNARSON H. , BENGOETXEA K. , PAU L. F.
Published: November 2004

This paper surveys the applications of vision to fish sorting, fish fillet sorting and detection of surface and sub-surface defects (such as worms and bones). It stresses the specific implementation context, needed performances, illumination, detection principle, as well as vision algorithms. Also analyzed are the optical properties of fish. Examples of results are given.
COMMUNICATION WITH A COMPUTER SYSTEM FROM THE PATTERN RECOGNITION POINT OF VIEW
Authors: FAIN V.S. , RUBANOV L.I.
Published: November 2004

The concept of K-stationarity of an environment in which a computer system (CS) works is introduced and the wide prevalence of such environments is pointed out. Their property of originating after a long period the problems belonging to a small number K of stable types leads to what is enough for a CS to only recognize the type of current problem. Thereafter the problem is solved by the algorithm previously prepared for that type. The problem of computer understanding of natural language (CUNL) can serve as an illustration. Any address made to a CS is a task, therefore a text analysis must reveal not its sense as in known constructions, but only the data about the task. However, in a K-stationary environment, those tasks can relate only to K known types, and this reduces the CUNL problem to the problem of recognition from a text of a proper algorithm (out of the K present) and of concrete values of its arguments, If a CS operates simultaneously in several subject areas (SA) then the stage of prerecognition of an SA is to be attached to the system. The CUNL systems under exploitation, which allow absolutely free and easy addressing within the SAs present, are described.
COMBINING EVIDENCE IN PROBABILISTIC RELAXATION
Authors: KITTLER J. , HANCOCK E.R.
Published: November 2004

We present a specification of the problem of combining evidence that arises in the approach to consistent object-labelling known as probabilistic relaxation. This specification differs from others in several important respects. Firstly, we ensure internal consistency by distinguishing between directly and indirectly interacting objects. Secondly, we avoid certain problems of interpretation and meaning by regarding the iterative updating of probabilities as a filtering process on the measurements for objects. Finally, we overcome the problem of the exponential complexity of the resulting evidence combining formula by deriving practical support functions of at most polynomial complexity. The computational realisation of the advocated approach to combining evidence is demonstrated for the application of edge labelling. This application includes details of how both the measurement generation process and the world-model may be expressed probabilistically and what the advantages are to be gained from using different forms of support-function.
MODEL-GUIDED ATTRIBUTED STRING MATCHING BY SPLIT-AND-MERGE FOR SHAPE RECOGNITION
Authors: TSAY YIH-TAY , TSAI WEN-HSIANG
Published: November 2004

Due to noise and distortion, segmentation uncertainty is a key problem in structural pattern analysis. In this paper we propose the use of the split operation for shape recognition by attributed string matching. After illustrating the disadvantage of attributed string matching using the merge operation, the split operation is proposed. Under the guidance of the model shape, an input shape can be reapproximated, using the split operation, into a new attributed string representation. By combining the split and the merge operations for shape matching it is unnecessary to apply any type of edit operation to a model shape. This makes the distance between the input shape and the model shape more meaningful and stable, and improves recognition results. An algorithm for attributed string matching by split-and-merge is proposed. To eliminate the effect of the numbers of primitives in the model shape on the shape distance, shape recognition based on a similarity measure is also proposed. Good experimental results prove the feasibility of the proposed approach for general shape recognition.
GENERATING RECTANGLES USING TWO-DIMENSIONAL GRAMMARS WITH TIME AND SPACE COMPLEXITY ANALYSES
Authors: LEE EDWARD T. , ZHU SHANG-YONG , CHU PENG-CHING
Published: November 2004

A two-dimensional grammar for generating all possible rectangles is presented and illustrated by examples. The time and space complexity analyses of this grammar together with a parallel context-free array grammar and a free grammar are also presented. Generating pictures using two-dimensional grammars appear to be a fertile field for further study. The study of two-dimensional grammars has useful applications in region filling. pattern recognition. robotics, pictorial information system design and related areas.
PUSHDOWN RECOGNIZERS FOR ARRAY PATTERN
Authors: LIN H. J. , WANG P. S. P.
Published: November 2004

We investigate the factors that make it difficult to generalize pushdown automata for one-dimensional strings to two-dimensional arrays. Then we resolve the problems and construct two-dimensional pushdown array automata (PDAA). The relationship between isometric context-free array languages and pushdown array automata is established. Several examples of array automata are presented, and a pushdown array automaton is tested on VAX8650/VMS using PASCAL.
COORDINATE GRAMMARS REVISITED: GENERALIZED ISOMETRIC GRAMMARS
Authors: ROSENFELD AZRIEL
Published: November 2004

In a "coordinate grammar", the rewriting rules replace sets of symbols having been given coordinates by sets of symbols whose coordinates are given functions of the coordinates of the original symbols. It was shown in 1972 that coordinate grammars are "too powerful"; even if the rules are all of finite-state types and the functions are all computable by finite transducers, the grammar has the power of a Turing machine. This paper shows that if we require the functions to be shift-invariant and the rules to be of bounded diameter, then such grammars do have a useful hierarchy of types; in fact, when we require that their sentential forms always remain connected, they turn out to be equivalent to "isometric grammars".
RELATIONSHIPS BETWEEN COORDINATE GRAMMARS AND PATH CONTROLLED GRAPH GRAMMARS
Authors: NAKAMURA AKIRA , AIZAWA KUNIO
Published: November 2004

We define a graph grammar called node-replacement graph grammar with path controlled embedding (nPCE grammars) which use a sequence of edges instead of the single edge to embed a newly replaced graph into the host graph, then show some relationships between two-dimensional "coordinate grammars" and nPCE grammars. We also suggest an extension of PCE grammars to describe "disconnected coordinate languages".
FINITE IMAGES GENERATED BY GL-SYSTEMS
Authors: SAOUDI A. , RANGARAJAN K. , DARE V. R.
Published: November 2004

In this paper, we introduce a new device called GL-systems (i.e. Grammar-Lindenmayer systems) for generating finite images. GL-systems are sequential/parallel systems in which the horizontal rules form a Chomskian grammar and the vertical rules form a DTOL system. We obtain hierarchical results of various types of GL-systems. We study some properties like, closure properties, combinatorial results, pumping lemma and decidability results. An algebraic characterization for GL-systems (with variation) is presented.
ENCRYPTION-DECRYPTION TECHNIQUES FOR PICTURES
Authors: SIROMONEY RANI , SUBRAMANIAN K. G. , ABISHA P. J.
Published: November 2004

Language theoretic public key cryptosystems for strings and pictures are discussed. Two methods of constructing public key cryptosystems for the safe transmission or storage of chain code pictures are presented; the first one encrypts a chain code picture as a string and the second one as a two-dimensional array.
TRANSLATION-, ROTATION- AND SCALE- INVARIANT RECOGNITION OF HAND-DRAWN SYMBOLS IN SCHEMATIC DIAGRAMS
Authors: LEE SEONG-WHAN , KIM JIN H. , GROEN FRANS C.A.
Published: November 2004

In this paper, a model-based scheme for recognizing hand-drawn symbols in schematic diagrams using attributed graph (AG) matching in the absence of any information concerning their pose (translation, rotation and scale) is described. The process of AG matching proceeds as follows. First, an observed AG (AGO) is constructed from single-pixel-width line-representation of an observed symbol. Second, the pose of the AGO is estimated in terms of translation, rotation and scale with respect to the model AGs (AGM s ). The search space is effectively pruned by introducing the concept of control vertex and applying geometrical constraints in an early stage. In this step, a small number of candidate AGM s are selected. Third, correspondences between components of the observed AG after normalization (AGON) and those of the AGMs are found for the given poses. Fourth, distance measures between the AGON and the AGM s are calculated, based upon the correspondences. Finally, the AGON is classified as the AGM with the minimum distance. Experimental results for hand-drawn symbols with and without templates show that using AG matching is very efficient and successful for translation-, rotation- and scale-invariant recognition of hand-drawn symbols in schematic diagrams.
TERMINAL WEIGHTED L-SYSTEMS
Authors: NIRMAL NALINAKSHI , RAMA R.
Published: November 2004

Terminal weights are attached to L-systems by replacing each terminal generated by an OL-system by fa(i) in the ith step of a derivation. The family of terminal weighted OL languages will be equal to the recursively enumerable set. Terminal weights are attached to EOL-regular matrix languages and also to OL array languages. Parquet deformations are generated by TWEOL-RMS.
ASSOCIATIVE RECALL BASED ON ABSTRACT OBJECT DESCRIPTIONS LEARNED FROM OBSERVATION: THE CBM NEURAL NET MODEL
Authors: ISRAEL PEGGY , KOUTSOUGERAS CRIS
Published: November 2004

The associative recall problem is approached here by means of a new neural net model. The model uses internal representations of objects automatically developed from observation. A feedback loop consisting of a Coulomb network is introduced to a classifier network. The classifier learns descriptions of various object types from observation of typical instances. The internal representations of the classifier are used by the Coulomb network to dynamically transform an incomplete or noisy input. Since the recall is based on abstract object descriptions the output is not limited to an a priori specified collection of memories (objects).
A PARALLEL ARCHITECTURE FOR AI NONLINEAR PLANNING
Authors: LEE SUKHAN , CHUNG KYUSIK
Published: November 2004

This paper presents a resource-level conflict detection and conflict resolution scheme which is combined with a state-level backward planning algorithm and provides efficient conflict detection and global conflict resolution for nonlinear planning. The scheme keeps track of the usage of individual resources during planning, and constructs a Resource-Usage Flow (RUF) structure (based on which conflict detection and resolution is accomplished). The RUF structure allows the system to perform minimal and nonredundant operations for conflict detection and resolution. Furthermore, resource-level conflict detection and resolution facilitates problem decomposition in terms of resources, thereby providing easy implementation in a parallel and distributed processing environment.

Performance analysis indicates that the proposed architecture has a speed-up factor of the average depth of a plan network, D(Na), compared to the distributed NOAH, where Na (the total number of action nodes at the completion of planning) and D(Na) are considerably larger than the number of resources involved in planning as well as the number of initial goal states.
A MODIFIED A* ALGORITHM FOR ROBUST PLAN RECOGNITION
Authors: CALISTRI RANDALL J.
Published: November 2004

The traditional problem of plan recognition can be solved in a straightforward manner by a graph-searching algorithm such as A*. A few simple extensions allow the algorithm to handle situations in which the user has an incorrect plan. However, it turns out that recognizing structural errors is computationally a much more complex problem than recognizing plans with simple constraint violations. Four algorithms are presented here, starting with a direct adaptation of A* for recognizing correct plans, and progressing to an optimized algorithm for recognizing violated, ill-formed plans.
AN EXPERT SYSTEM FOR TUNING PARTICLE BEAM ACCELERATORS
Authors: LAGER DARREL L. , BRAND HAL R. , MAURER WILLIAM J.
Published: November 2004

An expert system that acts as an intelligent assistant to operators tuning a particle beam accelerator was developed. The system incorporates three approaches to tuning: (1) Duplicating within a software program the reasoning and the procedures used by an operator to tune an accelerator. This approach has been used to steer particle beams through the transport section of Lawrence Livermore National Laboratory's Advanced Test Accelerator and through the injector section of the Experimental Test Accelerator. (2) Using a model to simulate the position of a beam in an accelerator. The simulation is based on data taken directly from the accelerator while it is running. This approach will ultimately be used by operators of the Experimental Test Accelerator to first compare actual and simulated beam performance in real time, then to determine which set of parameters is optimum in terms of centering the beam, and finally to feed those parameters to the accelerator. Operators can also use the model to determine if a component has failed. (3) Using a mouse to manually select and control the magnets that steer the beam. Operators on the Experimental Test Accelerator can also use the mouse to call up windows that display the horizontal and vertical positions of the beam as well as its current.
EXPERT SYSTEM APPROACH USING GRAPH REPRESENTATION AND ANALYSIS FOR VARIABLE-STROKE INTERNAL-COMBUSTION ENGINE DESIGN
Authors: SHEN STEWART N. T. , CHEW MENG-SANG , ISSA GHASSAN F.
Published: November 2004

Even though AI technology is a relatively new discipline, many of its concepts have already found practical applications. Expert systems, in particular, have made significant contributions to technologies in such fields as business, medicine, engineering design, chemistry, and particle physics.

This paper describes an expert system developed to aid mechanical engineering designers in the preliminary design of variable-stroke internal-combustion engines. Variable-stroke engines are more economical in fuel consumption but their design is particularly difficult to accomplish. With the traditional design approach, synthesizing the mechanisms for the design is rather difficult and evaluating the mechanisms is an even more cumbersome and time-consuming effort. Our expert system assists the designer by generating and evaluating a large number of design alternatives represented in the form of graphs. Through the application of structural and design rules obtained from design experts to the graphs, good quality preliminary design configurations of the engines are promptly deduced. This approach can also be used in designing other types of mechanisms.
A COMPARISON OF TWO NEW TECHNIQUES FOR CONCEPTUAL CLUSTERING
Authors: CRAWFORD STUART L. , SOUDERS STEVEN K.
Published: November 2004

Clustering, pattern recognition, and classification are important components of many artificial intelligence systems, especially those designed to classify new observations. Often, one has access to a history of old observations that have been previously classified and, under these circumstances, the old data may be used as a training set from which one may obtain rules for the subsequent classification of new data. The techniques used to obtain these rules may be traditional statistical methods or modern computer-intensive techniques. Sometimes, however, the history of old observations has not been previously classified. Under these circumstances, the analyst simply wishes to uncover structure in the data and ascertain whether the structure is apparent or real. When the analyst is searching for clusters, statistical clustering methodologies are often used. Although effective at locating clusters, such approaches leave the interpretation of the clusters as a task for the human analyst. A relatively new class of “conceptual” clustering techniques have emerged from the discipline of machine learning. These techniques attempt to both locate and explain clusters among the data. In this way, the explanations of cluster membership may be used to construct rules for the subsequent classification of new data. The generation of interpretable rules, whether by the use of classification algorithms or conceptual clustering algorithms is of considerable importance in reducing the knowledge acquisition “bottleneck” that often impedes progress towards the building of rule-based systems. In this paper, two new techniques for conceptual clustering are introduced and compared.
GENERATING FUNCTIONS FOR STOCHASTIC CONTEXT-FREE GRAMMARS
Authors: THOMASON MICHAEL G.
Published: November 2004

Stochastic context-free grammars are an important tool in syntactic pattern analysis and other applications as well. This paper discusses major results in single-type and multitype branching processes used to study a grammar’s stochastic derivations. Probability generating functions are well-established as a tool in this area and are used extensively here.
Principles of MAP Kinase Signaling Specificity inSaccharomyces cerevisiae
Authors: Schwartz Monica A. , Madhani Hiten D.
Published: November 2004

▪ Abstract  Cells respond to a plethora of signals using a limited set of intracellular signal transduction components. Surprisingly, pathways that transduce distinct signals can share protein components, yet avoid erroneous cross-talk. A highly tractable model system in which to study this paradox is the yeast Saccharomyces cerevisiae, which harbors three mitogen-activated protein kinase (MAPK) signal transduction cascades that share multiple signaling components. In this review we first describe potential mechanisms by which specificity could be achieved by signaling pathways that share components. Second, we summarize key features and components of the yeast MAPK pathways that control the mating pheromone response, filamentous growth, and the response to high osmolarity. Finally, we review biochemical analyses in yeast of mutations that cause cross-talk between these three MAPK pathways and their implications for the mechanistic bases for signaling specificity. Although much remains to be learned, current data indicate that scaffolding and cross pathway inhibition play key roles in the maintenance of fidelity.
B Cell Signaling and Tumorigenesis
Authors: Jumaa Hassan , Hendriks Rudolf W. , Reth Michael
Published: November 2004

▪ Abstract  The proliferation and differentiation of lymphocytes are regulated by receptors localized on the cell surface. Engagement of these receptors induces the activation of intracellular signaling proteins that transmit the receptor signals to distinct targets and control the cellular responses. The first signaling proteins to be discovered in higher organisms were the products of oncogenes. For example, the kinases Src and Abelson (Abl) were originally identified as oncogenes and were later characterized as important proteins for signal transduction in various cell types, including lymphocytes. Now, as many cellular signaling molecules have been discovered and ordered into certain pathways, we can better understand why particular signaling proteins are associated with tumorigenesis. In this review, we discuss recent progress in unraveling the molecular mechanisms of signaling pathways that control the proliferation and differentiation of early B cells. We point out the concepts of auto-inhibition and subcellular localization as crucial aspects in the regulation of B cell signaling.
ANTIGEN-SPECIFIC MEMORY B CELL DEVELOPMENT
Authors: McHeyzer-Williams Louise J. , McHeyzer-Williams Michael G.
Published: November 2004

▪ Abstract  Helper T (Th) cell–regulated B cell immunity progresses in an ordered cascade of cellular development that culminates in the production of antigen-specific memory B cells. The recognition of peptide MHC class II complexes on activated antigen-presenting cells is critical for effective Th cell selection, clonal expansion, and effector Th cell function development (Phase I). Cognate effector Th cell–B cell interactions then promote the development of either short-lived plasma cells (PCs) or germinal centers (GCs) (Phase II). These GCs expand, diversify, and select high-affinity variants of antigen-specific B cells for entry into the long-lived memory B cell compartment (Phase III). Upon antigen rechallenge, memory B cells rapidly expand and differentiate into PCs under the cognate control of memory Th cells (Phase IV). We review the cellular and molecular regulators of this dynamic process with emphasis on the multiple memory B cell fates that develop in vivo.
Arabic Poetry in West Africa: An Assessment of the Panegyric and Elegy Genres In Arabic Poetry of the 19th and 20th Centuries In Senegal and Nigeria
Authors: Abdullah Abdul-Samad
Published: November 2004

This article explores the form and content of West African Arabic poetry, with particular reference to Nigeria and Senegal. It analyses several key poetic features of this region of West Africa, with the focus on nineteenth and twentieth century poetry. The historical context is both the period of European colonisation and the pre-colonial period. The article suggests that Arabic poetry was a much older tradition in the region, that it was in no sense challenged by colonial rule, and that strong religious commitment is visible in its content. This study surveys the key influence of Arabian poetry on West African Arabic poetry. It analyses relevant texts and highlights the importance of a number of signi ficant issues relating to this area of study in the research of West African Islamic literature. The study also explores the extent of the intellectual in fluence of Islam. This is evidenced by the irrefutable presence of Arabisation at a time of Islamic penetration, as de fined by the distinctive Islamic character of West African Arabic poetry.
"Besotted with the Bright Lights of Imperialism":? Arab Subjectivity Constructed Against New York's Many Faces
Authors: Hartman Michelle
Published: November 2004

This article reads symbolism and imagery related to New York City in Yūsuf Idrīs's New York 80, Adūnīs's Qabr min ajl New York, and Radwā 'Āshūr's Al-Rihla, to advance two interrelated arguments about the formulation of a positive, modern Arab subjectivity. Firstly, though all of the texts criticize the United States and set up an opposition between the Arab self and the US other, none of the texts merely inscribes a simplistic self-other dichotomy. Analyzing this allows a more complex notion of Arab subjectivity to emerge. Secondly, gendered symbolism and imagery are manipulated in these texts and thus gender analyses are crucial to exploring the articulations of Arab subjectivity in these works.
African Christianity in the Jewish State: Adaptation, Accommodation and Legitimization of Migrant Workers' Churches, 1990-2003
Authors: Sabar Galia
Published: November 2004

This paper examines the role of African Initiated Churches (AICs) in the lives of African migrant laborers in Israel. Its aim is to attain a deeper understanding of religion and church affiliation among African migrant laborers in Israel from the perspective of the Africans themselves. It traces the creation and development of the AICs in Israel, including the various services and activities that the churches provided for their members in the social, economic and political arenas. It argues that the African churches in Israel occupied a particularly large and central place in their members' lives compared to migrant churches in other western diasporas, taking on roles of other traditional social, economic, political and civil actors in Africa. The paper examines the AICs' multiple adaptations to unique conditions in Israel and to the needs of their membership. Though many of the patterns identified are similar to those found in other diaspora communities, certain features of Israel and its society, mainly those connected to the Jewish identity of the State of Israel and the limited civic horizon open to non-Jews, made for substantial differences. These features forced Africans to create their own Afro-Christian space to fulfill their needs and became the key anchors in the spiritual, emotional and practical lives of the African migrants in Israel. Finally this article argues that the churches became the main space for the production of a sense of belonging within the Israeli civic context, in spite of the fact that the migrants' religious identities and institutions were not used as vehicles for recognition or channels for gaining legitimacy in Israel's public sphere.
The QME AERI LBLRTM: A Closure Experiment for Downwelling High Spectral Resolution Infrared Radiance
Authors: Turner D. D. , Tobin D. C. , Clough S. A. , Brown P. D. , Ellingson R. G. , Mlawer E. J. , Knuteson R. O. , Revercomb H. E. , Shippert T. R. , Smith W. L. , Shephard M. W.
Published: November 2004

Research funded by the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program has led to significant improvements in longwave radiative transfer modeling over the last decade. These improvements, which have generally come in small incremental changes, were made primarily in the water vapor self- and foreign-broadened continuum and the water vapor absorption line parameters. These changes, when taken as a whole, result in up to a 6 W m−2 improvement in the modeled clear-sky downwelling longwave radiative flux at the surface and significantly better agreement with spectral observations. This paper provides an overview of the history of ARM with regard to clear-sky longwave radiative transfer, and analyzes remaining related uncertainties in the ARM state-of-the-art Line-by-Line Radiative Transfer Model (LBLRTM).

A quality measurement experiment (QME) for the downwelling infrared radiance at the ARM Southern Great Plains site has been ongoing since 1994. This experiment has three objectives: 1) to validate and improve the absorption models and spectral line parameters used in line-by-line radiative transfer models, 2) to assess the ability to define the atmospheric state, and 3) to assess the quality of the radiance observations that serve as ground truth for the model. Analysis of data from 1994 to 1997 made significant contributions to optimizing the QME, but is limited by small but significant uncertainties and deficiencies in the atmospheric state and radiance observations. This paper concentrates on the analysis of QME data from 1998 to 2001, wherein the data have been carefully selected to address the uncertainties in the 1994–97 dataset. Analysis of this newer dataset suggests that the representation of self-broadened water vapor continuum absorption is 3%–8% too strong in the 750–1000 cm−1 region. The dataset also provides information on the accuracy of the self- and foreign-broadened continuum absorption in the 1100–1300 cm−1 region. After accounting for these changes, remaining differences in modeled and observed downwelling clear-sky fluxes are less than 1.5 W m−2 over a wide range of atmospheric states.
Observations and Numerical Simulations of Inertia–Gravity Waves and Shearing Instabilities in the Vicinity of a Jet Stream
Authors: Lane Todd P. , Doyle James D. , Plougonven Riwal , Shapiro Melvyn A. , Sharman Robert D.
Published: November 2004

The characteristics and dynamics of inertia–gravity waves generated in the vicinity of an intense jet stream/ upper-level frontal system on 18 February 2001 are investigated using observations from the NOAA Gulfstream-IV research aircraft and numerical simulations. Aircraft dropsonde observations and numerical simulations elucidate the detailed mesoscale structure of this system, including its associated inertia–gravity waves and clear-air turbulence. Results from a multiply nested numerical model show inertia–gravity wave development above the developing jet/front system. These inertia–gravity waves propagate through the highly sheared flow above the jet stream, perturb the background wind shear and stability, and create bands of reduced and increased Richardson numbers. These bands of reduced Richardson numbers are regions of likely Kelvin–Helmholtz instability and a possible source of the clear-air turbulence that was observed.
Initiation of Precipitation Episodes Relative to Elevated Terrain
Authors: Ahijevych D. A. , Davis C. A. , Carbone R. E. , Tuttle J. D.
Published: November 2004

The western and central United States experience a pronounced diurnal cycle in rainfall during the warm season. Over the higher terrain west of 105°W, most precipitation occurs in the afternoon, whereas the central United States experiences more nocturnal events. This coherent phase transition between the Rocky Mountains and the U.S. Great Plains is well defined for all warm seasons between 1996 and 2003, provided that the rainfall observations are remapped relative to the elevated terrain in the western United States prior to north–south averaging. Due to the westward shift of the Continental Divide north of 42°N and its intersection with the warm season storm track for 2002, the diurnal coherence greatly improves after remapping the 2002 rainfall observations. This speaks to the long-range influence of orography on precipitation frequency and suggests that the primary east–west corridor of precipitation for an individual warm season intersects the cordillera over a fairly narrow latitude range.
Surface Fluxes and Ocean Coupling in the Tropical Intraseasonal Oscillation
Authors: Maloney Eric D. , Sobel Adam H.
Published: November 2004

Sensitivity of tropical intraseasonal variability to mixed layer depth is examined in the modified National Center for Atmospheric Research Community Atmosphere Model 2.0.1 (CAM), with relaxed Arakawa–Schubert convection, coupled to a slab ocean model (SOM) whose mixed layer depth is fixed and geographically uniform, but varies from one experiment to the next. Intraseasonal west Pacific precipitation variations during boreal winter are enhanced relative to a fixed-SST (infinite mixed layer depth) simulation for mixed layer depths from 5 to 50 m, with a maximum at 20 m [interestingly, near the observed value in the regions where the Madden– Julian oscillation (MJO) is active], but are strongly diminished in the 2-m depth simulation. This nonmonotonicity of intraseasonal precipitation variance with respect to mixed layer depth was predicted by Sobel and Gildor using a highly idealized model. Further experiments with the same idealized model help to interpret results derived from the modified NCAR CAM.

A sensitivity study shows that the convection–surface flux feedback [wind-induced surface heat exchange (WISHE)] is important to the intraseasonal variability in the CAM. This helps to explain the behavior of the 2-m SOM simulation and the agreement with the idealized model. Although intraseasonal SST variations are stronger in the 2-m SOM simulation than in any of the other simulations, these SST variations are phased in such a way as to diminish the amplitude of equatorial latent heat flux variations. Reducing the mixed layer depth is thus nearly equivalent to eliminating WISHE, which in this model reduces intraseasonal variability. The WISHE mechanism in the model is nonlinear and occurs in a region of mean low-level westerlies.

Since a very shallow mixed layer is effectively similar to wet land, it is suggested that the mechanism described here may explain the local minimum in MJO amplitude observed over the Maritime Continent region.
Downscaling of Daily Rainfall Occurrence over Northeast Brazil Using a Hidden Markov Model
Authors: Robertson Andrew W. , Kirshner Sergey , Smyth Padhraic
Published: November 2004

A hidden Markov model (HMM) is used to describe daily rainfall occurrence at 10 gauge stations in the state of Ceará in northeast Brazil during the February–April wet season 1975–2002. The model assumes that rainfall occurrence is governed by a few discrete states, with Markovian daily transitions between them. Four “hidden” rainfall states are identified. One pair of the states represents wet-versus-dry conditions at all stations, while a second pair of states represents north–south gradients in rainfall occurrence. The estimated daily state-sequence is characterized by a systematic seasonal evolution, together with considerable variability on intraseasonal, interannual, and longer time scales. The first pair of states are shown to be associated with large-scale displacements of the tropical convergence zones, and with teleconnections typical of the El Niño–Southern Oscillation and the North Atlantic Oscillation.

A nonhomogeneous HMM (NHMM) is then used to downscale daily precipitation occurrence at the 10 stations, using general circulation model (GCM) simulations of seasonal-mean large-scale precipitation, obtained with historical sea surface temperatures prescribed globally. Interannual variability of the GCM's large-scale precipitation simulation is well correlated with seasonal- and spatial-averaged station rainfall-occurrence data. Simulations from the NHMM are found to be able to reproduce this relationship. The GCM-NHMM simulations are also able to capture quite well interannual changes in daily rainfall occurrence and 10-day dry spell frequencies at some individual stations. It is suggested that the NHMM provides a useful tool (a) to understand the statistics of daily rainfall occurrence at the station level in terms of large-scale atmospheric patterns, and (b) to produce station-scale daily rainfall sequence scenarios for input into crop models, etc.
NGOs and uneven development: geographies of development intervention
Authors: Bebbington Anthony
Published: November 2004

Much research on nongovernmental organizations (NGOs) involved in international development has been case-study-based, with questions about the broader geographies of NGO intervention rarely asked. This paper explores the factors that drive such NGO geographies and considers how they relate to the uneven geographies of poverty and livelihood produced under contemporary processes of capitalist expansion and contraction. Explanations of NGO presence and absence must of necessity be historicized and contextualized, and particular attention should be paid to the influences of the politics and political economy of aid and development, the geographies of religious, political and other social institutions, the transnational networks in which these institutions are often embedded, and the social networks and life histories of NGO professionals and allies. The resulting geographies of intervention pattern the uneven ways in which NGOs become involved in reworking places and livelihoods, though this reworking is also structured by the dynamics of political economy. The paper closes by drawing out implications for geographical research on NGOs, as well as for efforts to theorize the relationships between intentional development interventions and immanent processes of political economic change, and their effects on inequality and unevenness.
Spatial choice modelling: new opportunities to incorporate space into substitution patterns
Authors: Hunt Len M. , Boots Barry , Kanaroglou Pavios S.
Published: November 2004

This paper is designed to review recent developments in choice modelling that offer promise for studying spatial choices. In particular, we focus on the ability of general choice models to account for a richer pattern of spatial substitution than afforded by early choice models. We argue that the generality offered by these choice models is sufficient to rethink the current view that spatial choice is a distinct field of inquiry. Our conclusion is that, while space complicates choice models, contemporary aspatial choice models are general enough to accommodate these complexities.
An Efficient Dye-sensitized Photoelectrochemical Solar Cell Made from CaCO3-coated TiO2 Nanoporous Film
Authors: Okada Nobuhiro , Karuppuchamy Subbian , Kurihara Masaaki
Published: November 2004

A convenient —and quick to realize— approach for the synthesis of an ultrathin overlayer of CaCO3 on TiO2 thin films is suggested. Since dye-sensitized photoelectrochemical investigations on CaCO3-thin-layer-coated TiO2 nanoporous films are hitherto unreported, we performed such investigations by sensitizing our TiO2–CaCO3 films with tetrabutylammonium cis-di(thiocyanato)-N,N′-bis(4-carboxylato-4′-carboxylic acid-2,2′-bipyridine)ruthenate(II) and achieved power conversion efficiencies over 9.3% under illumination of AM 1.5 simulated sunlight (95 mW/cm2).
Single Crystal Ni5Zn21 Nanowire Arrays Fabricated by Electrodeposition in Anodic Alumina Membranes
Authors: Jia Chong , Liu Weifeng , Zhang Bei , Jin Chuangui , Yao Lianzeng , Cai Weili , Li Xiaoguang
Published: November 2004

Large-area, high-filling rate, uniform, and single-crystal Ni5Zn21 nanowire arrays have successfully been synthesized by dc electrodeposition into the nanochannels of anodic alumina membranes (AAM).
Chlorophyll Chemiluminescence Emitted by Chlorin Ring Cleavage with Acetonitrile and Hydrogen Peroxide
Authors: Nagoshi Toshimasa , Igarashi Shukuro
Published: November 2004

In the presence of acetonitrile and NaOH, when H2O2 was added to the solution containing chlorophyll, it was found that a strong chemiluminescence (CL) was emitted. The blue light was emitted with the decomposition of chlorophyll. It is considered that the emitter contains the decomposition products of chlorophyll based on the following measurement results, such as the reduction of absorbance for chlorophyll and the difference of the spectral form between fluorescence and CL. The CL of the chlorines, such as chlorophyll, and the porphyrin analogue compounds were compared under the same conditions. Consequently, the obtained CL was strong in the chlorin complex which contains Mg or Zn. On the other hand, the CL was not strongly observed with porphyrin compounds. In the chlorophyll CL, when the chlorin ring is oxidized by the generated •O2−, the excited molecule would be produced in the process of ring cleavage, and then CL is emitted to the outside.
A One-pot Synthesis of Terminal Alkynes from anti-3-Aryl-2,3-dibromopropanoic Acids under Microwave Irradiation
Authors: Kuang Chunxiang , Senboku Hisanori , Tokuda Masao
Published: November 2004

A facile one-pot synthesis of terminal alkynes was achieved by microwave irradiation of a mixture of anti-3-aryl-2,3-dibromopropanoic acids, Et3N and DMF and subsequent irradiation in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). This method requires short reaction time (1–2 min) and gives terminal alkynes in high yields.